Coordinated by CRHEA-CNRS research laboratory, this monthly newsletter is produced by Knowmade with collaboration from the managers of GANEX groups. The newsletter presents a selection of newest scientific publications, patent applications and press releases related to III-Nitride semiconductor materials (GaN, AlN, InN and alloys)

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GANEX Newsletter No. 65 June 2018

III-N Technology

GaNEX | III-N Technology Newsletter No. 65 | 2

METHODOLOGY

Each month

150+ new scientific publications

200+ new patent applications

30+ new press releases

Sources 10+ scientific journal editors

Elsevier, IOP, IEEE, Wiley, Springer, APS, AIP, AVS, ECS, Nature, Science …

10+ specialist magazines Semiconductor Today, ElectoIQ, i-micronews,

Compound Semiconductor, Solid State Technology … 5+ open access database: FreeFulPDF, DOAJ …

Patent database: Questel-Orbit

Selection by III-N French

experts

GANEX monthly newsletter

GaNEX | III-N Technology Newsletter No. 65 | 3

TABLE OF CONTENTS (clickable links to chapters)

SCIENTIFIC PUBLICATIONS ............................................................................................................................. 4

GROUP 1 - LEDs and Lighting ................................................................................................................................. 4

GROUP 2 - Laser and Coherent Light ..................................................................................................................... 8

GROUP 3 - Power Electronics .............................................................................................................................. 11

GROUP 4 - Advanced Electronics and RF ............................................................................................................. 19

GROUP 5 – MEMS and Sensors............................................................................................................................ 24

GROUP 6 - Photovoltaics and Energy harvesting................................................................................................. 27

GROUP 7 - Materials, Technology and Fundamental .......................................................................................... 30

PRESS RELEASE ............................................................................................................................................ 39

PATENT APPLICATIONS ................................................................................................................................ 72

GaNEX | III-N Technology Newsletter No. 65 | 4

SCIENTIFIC PUBLICATIONS Selection of new scientific articles

GROUP 1 - LEDs and Lighting Group leader: Benjamin Damilano (CRHEA-CNRS)

Information selected by Benjamin Damilano (CRHEA-CNRS)

Moth eye-inspired anti-reflective surfaces for

improved IR optical systems & visible LEDs

fabricated with colloidal lithography and etching Department of Chemical Engineering, University of

California, Santa Barbara, Santa Barbara, CA 93106-5080,

United States of America

Department of Molecular, Cellular, and Developmental

Biology, University of California, Santa Barbara, Santa

Barbara, CA 93106-9625, United States of America

Institute for Collaborative Biotechnologies, University of

California, Santa Barbara, Santa Barbara, CA 93106-5100,

United States of America

Bioinspiration & Biomimetics

https://doi.org/10.1088/1748-3190/aab738

Near- and sub-wavelength photonic structures are

used by numerous organisms (e.g. insects,

cephalopods, fish, birds) to create vivid and often

dynamically-tunable colors, as well as create,

manipulate, or capture light for vision,

communication, crypsis, photosynthesis, and

defense. This review introduces the physics of moth

eye (ME)-like, biomimetic nanostructures and

discusses their application to reduce optical losses

and improve efficiency of various optoelectronic

devices, including photodetectors, photovoltaics,

imagers, and light emitting diodes. Light–matter

interactions at structured and heterogeneous

surfaces over different length scales are discussed, as

are the various methods used to create ME-inspired

surfaces. Special interest is placed on a simple,

scalable, and tunable method, namely colloidal

lithography with plasma dry etching, to fabricate ME-

inspired nanostructures in a vast suite of materials.

Anti-reflective surfaces and coatings for IR devices

and enhancing light extraction from visible light

emitting diodes are highlighted.

Monolithically integrated InGaN/GaN light-emitting

diodes, photodetectors, and waveguides on Si

substrate Department of Electrical and Electronic Engineering, The

University of Hong Kong, Hong Kong, China

Grünberg Research Centre, Nanjing University of Posts and

Telecommunications, Nanjing 210003, China

Department of Electronic and Computer Engineering, Hong

Kong University of Science and Technology, Hong Kong,

China

Optica

https://doi.org/10.1364/OPTICA.5.000564

The characteristics of monolithically integrated light-

emitting diodes (LEDs), photodetectors (PDs), and

waveguides on a GaN-on-Si wafer are investigated.

The InGaN/GaN multi-quantum wells, which are

responsible for blue light emission in LEDs, are also

used for photodetection in PDs. Despite the Stokes

shift, a spectral overlap of ∼25  nm between the

emission and absorption spectra provides the PDs

with sufficient photosensitivity to signals from the

emitter while remaining insensitive to ambient

lighting. Optical interconnects in the form of linear or

bent suspended waveguides bridging the LEDs and

PDs are formed by selective detachment of etched

GaN mesas from the Si substrate. Additionally, the

PDs can be detached from the substrate and

remounted on an elevated platform, owing to the

flexibility of the thin-film waveguide. The

150  μm×150  μm LEDs and PDs exhibit rapid

response on nanosecond time scales, which is

attributed to fast radiative recombinations as well as

minimized resistive-capacitive (RC) delays, enabling

transmission of pseudorandom binary sequence

(PRBS) data signals at rates of 250 Mb/s with an

opening in the eye diagram. Together with

multichannel transmission free of crosstalk, the

ability of the planar and three-dimensional

monolithic photonic systems to handle visible-light

communication (VLC) applications is demonstrated.

GaNEX | III-N Technology Newsletter No. 65 | 5

High Light Extraction Efficiency of Deep Ultraviolet

LEDs Enhanced Using Nanolens Arrays Wuhan National Laboratory for Optoelectronics, Huazhong

University of Science and Technology, Wuhan 430074,

China

School of Mechanical Science and Engineering, Huazhong

University of Science and Technology, Wuhan 430074,

China

School of Optical and Electronic Information, Huazhong

University of Science and Technology, Wuhan 430074,

China

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2823742

To improve the light extraction efficiency (LEE) of

AlGaN-based deep ultraviolet LEDs (DUV-LEDs) by

simple and effective method, this has greatly

attracted ever-growing attention in DUV-LEDs field.

Here, nanolens arrays (NLAs) fabricated by

nanophotolithography and wet-etched technique is

proposed to improve the LEE of DUV-LEDs, and its

theoretical feasibility is verified by the Monte Carlo

Ray-Trace method and finite element analysis which

show an obvious improvement of light and electric

field distribution benefit from NLAs structure. By

controlling the time of wet etching, the effect of the

uniform patterns of NLAs with adjustable morphology

on the LEE of DUV-LEDs is systematically studied.

Compared with the sandwiched flat lens,

experimental results show that the obviously

enhancements of the light output power are

achieved by using the proposed NLAs to be 13.0%,

21.1%, 24.7%, 13.0%, and 11.5%, respectively,

corresponding to their radius of 325, 340, 350, 360,

and 400 nm, under the driving current of 300 mA.

Therefore, the highest light output power of DUV-

LEDs is used the optimized NLAs with radius of 350

nm, and its emission angle also shows the largest

improvement of ~14°, suggesting the best LEE.

Carrier dynamics of InxGa1-xN/GaN multiple

quantum wells grown on (−201) β-Ga2O3 for bright

vertical light emitting diodes King Abdullah University of Science and Technology

(KAUST), Physical Science and Engineering Division, Thuwal

23955-6900, Saudi Arabia

Imaging and Characterization Laboratory, King Abdullah

University of Science and Technology (KAUST), Thuwal

23955-6900, Saudi Arabia

Optics Express

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-

26-12-14869

High-quality InxGa1-xN/GaN multi-quantum well

(MQW) structures (0.05≤x≤0.13), are successfully

grown on transparent and conductive (−201)-

oriented β-Ga2O3 substrate. Scanning-transmission

electron microscopy and secondary ion mass

spectrometry (SIMS) show well-defined high quality

MQWs, while the In and Ga compositions in the wells

and the barriers are estimated by SIMS.

Temperature-dependant Photoluminescence (PL)

confirms high optical quality with a strong bandedge

emission and negligble yellow band. time-resolved PL

measurements (via above/below-GaN bandgap

excitations) explain carrier dynamics, showing that

the radiative recombination is predominant. Our

results demonstrate that (−201)-oriented β-Ga2O3 is

a strong candidate as a substrate for III-nitride-based

vertical- emitting devices.

Comparative study on luminescence extraction

strategies of LED by large-scale fabrication of

nanopillar and nanohole structures Ningbo Institute of Materials Technology and Engineering,

Chinese Academy of Sciences, Ningbo, 315201 Zhejiang,

People's Republic of China

Changchun University of Science and Technology, National

Key Lab of High Power Semiconductor Lasers, Changchun,

130022 Jilin, People's Republic of China

University of Chinese Academy of Sciences, Beijing 100049,

People's Republic of China

Advanced Micro-Fabrication Equipment Inc., Shanghai

201201, People's Republic of China

Zhejiang Key Laboratory for Advanced Microelectronic

Intelligent Systems and Applications, Hangzhou, 310007,

Zhejiang, People's Republic of China

Journal of Physics D: Applied Physics

https://doi.org/10.1088/1361-6463/aac31e

Light extraction and current injection are two

important considerations in the development of high

efficiency light-emitting-diodes (LEDs), but usually

cannot be satisfied simultaneously in nanostructure

patterned devices. In this work, we investigated near-

UV LEDs with nanopillar and nanohole patterns to

improve light extraction efficiency.

Photoluminescence (PL) intensities were enhanced by

GaNEX | III-N Technology Newsletter No. 65 | 6

8.0 and 4.1 times for nanopillar and nanohole LEDs

compared to that of planar LED. Nanopillar LED

exhibits higher PL emission than that of the nanohole

LED, attributing to a convex shape sidewall for more

effective outward light scattering, and reduction of

quantum-confined-stark-effect owing to strain

relaxation. However, nanopillar LED exhibits lower

electroluminescence intensity than the nanohole

sample, which calls for further optimization in carrier

distributions. Experimental results were further

supported by near-field electric field simulations. This

work demonstrates the difference in optical and

electrical behaviors between the nanopillar and

nanohole LEDs, paving the way for detailed

understanding on luminescence extraction

mechanisms of nanostructure patterned UV emitters.

GaN light-emitting device based on ionic liquid

electrolyte Department of Applied Physics, Nagoya University, Nagoya

464-8603, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06HE05

Ionic liquids (ILs) are attractive materials for

fabricating unique hybrid devices based on

electronics and electrochemistry; thus, IL-gated

transistors and organic light-emitting devices of light-

emitting electrochemical cells (LECs) are investigated

for future low-voltage and high-performance devices.

In LECs, voltage application induces the formation of

electrochemically doped p–n homojunctions owing to

ion rearrangements in composites of semiconductors

and electrolytes, and achieves electron–hole

recombination for light emission at the

homojunctions. In this work, we applied this concept

of IL-induced electrochemical doping to the

fabrication of GaN-based light-emitting devices. We

found that voltage application to the layered IL/GaN

structure accumulated electrons on the GaN surface

owing to ion rearrangements and improved the

conductivity of GaN. The ion rearrangement also

enabled holes to be injected by the strong electric

field of electric double layers on hole injection

contacts. This simultaneous injection of holes and

electrons into GaN mediated by ions achieves light

emission at a low voltage of around 3.4 V. The light

emission from the simple IL/GaN structure indicates

the usefulness of an electrochemical technique in

generating light emission with great ease of

fabrication.

Integrating AlInN interlayers into InGaN/GaN

multiple quantum wells for enhanced green

emission Center for Photonics and Nanoelectronics, Department of

Electrical and Computer Engineering, Lehigh University,

Bethlehem, Pennsylvania 18015, USA

Appl. Phys. Lett.

https://doi.org/10.1063/1.5028257

Significant enhancement in green emission by

integrating a thin AlInN barrier layer, or interlayer

(IL), in an InGaN/GaN multiple quantum well (MQW)

is demonstrated. The MQWs investigated here

contains 5 periods of an InGaN QW, a 1 nm thick

AlInN IL, and a 10 nm thick GaN barrier grown by

metalorganic chemical vapor deposition. To

accommodate the optimum low-pressure (20 Torr)

growth of the AlInN layer a growth flow sequence

with changing pressure is devised. The AlInN IL

MQWs are compared to InGaN/AlGaN/GaN MQWs

(AlGaN IL MQWs) and conventional InGaN/GaN

MQWs. The AlInN IL MQWs provide benefits that are

similar to AlGaN ILs, by aiding in the formation of

abrupt heterointerfaces as indicated by X-ray

diffraction omega-2theta (ω-2θ) scans, and also

efficiency improvements due to high temperature

annealing schedules during barrier growth. Room

temperature photoluminescence of the MQW with

AlInN ILs shows similar performance to MQWs with

AlGaN ILs, and ∼4–7 times larger radiative efficiency

(pump intensity dependent) at green wavelengths

than conventional InGaN/GaN MQWs. This study

shows the InGaN-based MQWs with AlInN ILs are

capable of achieving superior performance to

conventional InGaN MQWs emitting at green

wavelengths.

Oxygen-induced high diffusion rate of magnesium

dopants in GaN/AlGaN based UV LED

heterostructures Institute of Electronic Materials Technology, Wólczyńska

133, 01-919 Warsaw, Poland

GaNEX | III-N Technology Newsletter No. 65 | 7

Phys. Chem. Chem. Phys.

http://dx.doi.org/10.1039/C8CP01470A

Further development of GaN/AlGaN based

optoelectronic devices requires optimization of the p-

type material growth process. In particular,

uncontrolled diffusion of Mg dopants may decrease

the performance of a device. Thus it is meaningful to

study the behavior of Mg and the origins of its

diffusion in detail. In this work we have employed

secondary ion mass spectrometry to study the

diffusion of magnesium in GaN/AlGaN structures. We

show that magnesium has a strong tendency to form

Mg–H complexes which immobilize Mg atoms and

restrain their diffusion. However, these complexes

are not present in samples post-growth annealed in

an oxygen atmosphere or Al-rich AlGaN structures

which naturally have a high oxygen concentration. In

these samples, more Mg atoms are free to diffuse

and thus the average diffusion length is considerably

larger than for a sample annealed in an inert

atmosphere.

GaNEX | III-N Technology Newsletter No. 65 | 8

GROUP 2 - Laser and Coherent Light Group leader: Bruno Gayral (CEA)

Information selected by Knowmade

Enhanced performance of 450 nm GaN laser diodes

with an optical feedback for high bit-rate visible

light communication Optoelectronic Research Laboratory, Department of

Electrical Engineering, King Fahd University of Petroleum &

Minerals (KFUPM), Saudi Arabia

Conference on Lasers and Electro-Optics

https://doi.org/10.1364/CLEO_AT.2018.JTu2A.29

First report on significant performance improvement

of 450 nm blue edge-emitting laser in terms of optical

linewidth (~6.5 times), modulation bandwidth (~16%)

and SMSR (~7.4 times) by employing self-injection

locking scheme.

Reduction of Lasing Threshold of GaN-Based

Vertical-Cavity Surface-Emitting Lasers by Using

Short Cavity Lengths Optoelectronics Engineering Research Center, Department

of Electronic Engineering, College of Electronic Science and

Technology, Xiamen University, Xiamen 361005, China

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2825992

Ultralow lasing threshold of 413 μJ/cm² in GaN-based

vertical-cavity surface-emitting lasers (VCSELs) was

observed by reducing the cavity lengths between

double-side dielectric distributed Bragg reflectors to

6łambda. To the best of our knowledge, the

threshold is the lowest value ever reported in nitride

optically pumped VCSEL. The spontaneous emission

factor (β) was 0.1, and the degree of polarization was

91%. Effects of short cavity on spontaneous emission

factors, gain coefficient enhancement, and

absorption reduction were analyzed. In addition,

effects of coupled quantum wells on the confinement

factor were also discussed. We believe that our

results would be meaningful for refining nitride

VCSEL structure in the future.

GaN-based vertical-cavity surface-emitting lasers

with tunnel junction contacts grown by metal-

organic chemical vapor deposition Department of Electrical and Computer Engineering,

University of California, Santa Barbara, CA 93106, U.S.A.

Materials Department, University of California, Santa

Barbara, CA 93106, U.S.A.

Applied Physics Express

https://doi.org/10.7567/APEX.11.062703

We report the first demonstration of III–nitride

vertical-cavity surface-emitting lasers (VCSELs) with

tunnel junction (TJ) intracavity contacts grown

completely by metal–organic chemical vapor

deposition (MOCVD). For the TJs, n++-GaN was grown

on in-situ activated p++-GaN after buffered HF

surface treatment. The electrical properties and

epitaxial morphologies of the TJs were first

investigated on TJ LED test samples. A VCSEL with a TJ

intracavity contact showed a lasing wavelength of

408 nm, a threshold current of ~15 mA (10 kA/cm2),

a threshold voltage of 7.8 V, a maximum output

power of 319 µW, and a differential efficiency of

0.28%.

Lateral Current Spreading in III-N Ultraviolet

Vertical-Cavity Surface-Emitting Lasers Using

Modulation-Doped Short Period Superlattices School of Electrical and Computer Engineering, Georgia

Institute of Technology, Atlanta, GA, USA

Department of Physics and Astronomy, Arizona State

University, Tempe, Arizona, USA

IEEE Journal of Quantum Electronics

https://doi.org/10.1109/JQE.2018.2836667

Impact Statement:

All VCSELs made of III-N materials so far use ITO as a

lateral current spreading layer. This is good for visible

light emitters, but at UV wavelengths ITO has very

high optical losses, making it unsuitable for VCSELs. In

this manuscript, we describe the benefits of using

modulation-doped short period superlattices as

current spreading layers in UV light emitters. A

GaNEX | III-N Technology Newsletter No. 65 | 9

systematic study of threshold current and slope

efficiency as a function of the hole mobility in the

unintentionally doped narrow bandgap layer has

been performed, and the impacts of imperfect

modulation doping have been quantified.

Furthermore, we have discussed techniques to

experimentally realize these structures, citing recent

literature of GaN-based modulation doped

superlattices, and MBE regrowth on MOCVD

material.

Abstract:

Lateral hole injection into AlGaN-based ultraviolet

(UV) vertical-cavity light-emitting lasers (VCSELs) has

been studied via numerical simulation. For blue and

violet vertical cavity light emitters, indium tin oxide

(ITO) is most commonly used as a transparent current

spreading layer to increase the overlap between the

optical mode and the radial current profile. However,

ITO has very high optical losses in the UV spectrum,

so alternative schemes for lateral current spreading

have been investigated for use in UV-VCSELs. A

modulation doped short-period superlattice (MD-

SPSL) has been proposed as a transparent lateral

current spreading layer in UV-VCSELs. The narrow

bandgap unintentionally doped (uid) material

maintains a high mobility due to reduced impurity

scattering and has a high free hole concentration due

to modulation doping, thus forming highly conductive

channels which aid lateral hole transport. This has

been shown to partially mitigate current crowding

around the current aperture. To account for

imperfect modulation doping due to the magnesium

memory effects and other factors, the effect of

varying the hole mobility in the uid-narrow bandgap

layer of the MD-SPSL from 13–300 cm2/( V⋅s ) on the

threshold current and slope efficiency has also been

studied. Employing an MD-SPSL results in a significant

reduction in the threshold current and slope

efficiency compared to ITO, and the extent of the

improvement depends on the hole mobility in the

uid-AlGaN layer.

Vertical Electrical Conductivity of ZnO/GaN

Multilayers for Application in Distributed Bragg

Reflectors Department of Microtechnology and Nanoscience,

Chalmers University of Technology, Gothenburg, Sweden

Department of Physics, Chalmers University of Technology,

Gothenburg, Sweden

IEEE Journal of Quantum Electronics

https://doi.org/10.1109/JQE.2018.2836673

Impact Statement:

The difficulty in growing high-quality electrically

conductive n-type distributed Bragg reflectors (DBRs)

has limited the performance of III-nitride vertical-

cavity surface-emitting lasers (VCSELs). Recently, we

demonstrated the growth of ZnO/GaN DBRs, which is

a very promising alternative to pure III-nitride DBRs.

In this paper, we investigate the vertical electrical

conductivity of ZnO/GaN multilayers, both

experimentally and through simulations. We show

that the specific series resistance is comparable to, or

lower than, the best results reported for III-nitride

DBRs. In addition, our electrical simulations show the

benefits of using strained ZnO/GaN DBRs for reaching

low resistance compared to strained AlN/GaN DBRs.

It should also be mentioned that there are no

previous investigations of the electrical properties of

ZnO/GaN multilayers published in peer-reviewed

journals.

Abstract:

We have demonstrated an electrically conductive

ZnO/GaN multilayer structure using hybrid plasma-

assisted molecular beam epitaxy. Electrical I - V

characteristics were measured through the top three

pairs of a six pair ZnO/GaN sample. The total

measured resistance was dominated by lateral and

contact resistances, setting an upper limit of

∼10−4Ω⋅cm2 for the vertical specific series resistance

of the stack. A strong contribution to the low

resistance is the cancellation of spontaneous and

piezoelectric polarization that occurs in the in-plane

strained ZnO/GaN sample, as shown by electrical

simulations. In addition, the simulations show that

the actual vertical resistance of the sample could in

fact be three orders of magnitude lower and that

ZnO/GaN structures with thicknesses fulfilling the

Bragg condition should have similar resistance. Our

GaNEX | III-N Technology Newsletter No. 65 | 10

results suggest that ZnO/GaN distributed Bragg

reflectors (DBRs) are a promising alternative to pure

III-nitride DBRs in GaN-based vertical-cavity surface-

emitting lasers.

Intersubband Raman gain in strained zincblende III-

nitride-based step asymmetric quantum wells: non-

parabolicity effects Grupo de Materia Condensada-UdeA, Instituto de Física,

Facultad de Ciencias Exactas y Naturales, Universidad de

Antioquia UdeA, Medellín, Colombia

Centro de Investigación en Ciencias-IICBA, Universidad

Autónoma del Estado de Morelos, Cuernavaca, Mexico

Optical and Quantum Electronics

https://doi.org/10.1007/s11082-018-1504-2

The conduction band states in step-like strained

zincblende nitride-based quantum wells are

theoretically investigated including effects of band

non-parabolicity. In particular, the intersubband

Raman gain is calculated in order to identify the

possible use of this kind of structures as sources of

THz Raman lasing. The theoretical procedure includes

the use of the envelope function approximation,

taking into account strain effects on the conduction

band offset and position-dependent non-parabolic

effective masses. Three-level Raman gain is reported

for a group of possible intersubband transitions. The

results are discussed in terms of the variation of the

geometry of the heterostructure as well as the

concentration of In in the well regions. It is shown

that under a suitable geometric design and plausible

detuning conditions it is possible to achieve–for

certain intersubband transitions–values of the

intersubband Raman gain above 1000cm−1 , quite

larger than those previously reported in GaAs- and

wurtzite GaN-based double asymmetric quantum

wells. Besides, it is found that the band-

nonparabolicity acts as a significant element that

reduces the Raman gain response in this kind of

systems, whereas strain affects it in the same way

but the changes are mainly noticed for higher In

contents. It turns out that it is necessary to take both

effects into account for the better quantitative

description on intersubband Raman response in

zincblende nitride heterostructures.

On-wafer fabrication of cavity mirrors for InGaN-

based laser diode grown on Si Key Laboratory of Nanodevices and Applications, Suzhou

Institute of Nano-Tech and Nano-Bionics, Chinese

Academy of Sciences, Suzhou, 215123, China

School of Nano Technology and Nano Bionics, University of

Science and Technology of China, Hefei, 230026, China

Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese

Academy of Sciences, Nanchang, 330200, China

University of Science and Technology Beijing, Beijing,

100083, China

Scientific Reports

https://doi.org/10.1038/s41598-018-26305-8

Direct bandgap III-V semiconductor lasers grown on

silicon (Si) are highly desired for monolithic

integration with Si photonics. Fabrication of

semiconductor lasers with a Fabry–Pérot cavity

usually includes facet cleavage, however, that is not

compatible with on-chip photonic integration.

Etching as an alternative approach holds a great

advantage in preparing cavity mirrors with no need of

breaking wafer into bars. However, gallium nitride

(GaN) sidewalls prepared by dry etching often have a

large roughness and etching damages, which would

cause mirror loss due to optical scattering and carrier

injection loss because of surface non-radiative

recombination. A wet chemical polishing process of

GaN sidewall facets formed by dry etching was

studied in detail to remove the etching damages and

smooth the vertical sidewalls. The wet chemical

polishing technique combined with dry etching was

successfully applied to the on-wafer fabrication of

cavity mirrors, which enabled the realization of room

temperature electrically injected InGaN-based laser

diodes grown on Si.

GaNEX | III-N Technology Newsletter No. 65 | 11

GROUP 3 - Power Electronics Group leader: Frédéric Morancho (LAAS-CNRS)

Information selected by Frédéric Morancho (LAAS-CNRS) and Yvon Cordier (CRHEA-CNRS)

Low-temperature formation of Ga-oxide/GaN

interface with remote oxygen plasma and its

interface properties Graduate School of Engineering, Nagoya University,

Nagoya 464-8603, Japan

National Institute of Advanced Industrial Science and

Technology (AIST), GaN Advanced Device Open Innovation

Laboratory (GaN-OIL), Nagoya 464-8603, Japan

Nagoya University Institute of Materials and Systems for

Sustainability (IMaSS), Nagoya 464-8603, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06JE01

The Ga-oxide/GaN structures formed by remote

oxygen plasma (ROP) exposure at various

temperatures (T s) and times have been

systematically investigated. X-ray photoelectron

spectroscopy clarified the formation of Ga2O3 layers

with close-to-stoichiometric composition and a slight

N incorporation of ~6 at. %. Also, we found that a

high T s increases the intensity of a signal related to

the N–O bond, which is located near the Ga-

oxide/GaN interfaces. Total photoelectron yield

spectroscopy (PYS) also revealed that the ROP

exposure at T s of 300 °C produces fewer filled defect

states in the bandgap of GaN than at 500 °C. This

difference in the filled defect states could be

attributable to the amount of N–O bonds at the

interface.

Interface properties of SiO2/GaN structures formed

by chemical vapor deposition with remote oxygen

plasma mixed with Ar or He Graduate School of Engineering, Nagoya University,

Nagoya 464-8603, Japan

National Institute of Advanced Industrial Science and

Technology (AIST), GaN Advanced Device Open Innovation

Laboratory (GaN-OIL), Nagoya 464-8601, Japan

Nagoya University Institute of Materials and Systems for

Sustainability (IMaSS), Nagoya 464-8603, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06KA01

The impacts of noble gas species (Ar and He) on the

formation of a SiO2/GaN structure formed by a

remote oxygen plasma-enhanced chemical vapor

deposition (ROPE-CVD) method were systematically

investigated. Atomic force microscopy revealed that

ROPE-CVD with He leads to a smooth SiO2 surface

compared with the case of Ar. We found that no

obvious oxidations of the GaN surfaces after the SiO2

depositions with the both Ar and He cases were

observed. The capacitance–voltage (C–V) curves of

the GaN MOS capacitors formed by ROPE-CVD with

the Ar and He dilutions show good interface

properties with no hysteresis and good agreement

with the ideal C–V curves even after post deposition

annealing at 800 °C. Besides, we found that the

current density–oxide electric field characteristics

shows a gate leakage current for the Ar case lower

than the He case.

Effect of incorporation of nitrogen atoms in Al2O3

gate dielectric of wide-bandgap-semiconductor

MOSFET on gate leakage current and negative fixed

charge Graduate School of Engineering, Nagoya University,

Nagoya 464-8603, Japan

Institute of Materials and Systems for Sustainability,

Nagoya University, Nagoya 464-8603, Japan

Graduate School of Engineering, Osaka University, Suita,

Osaka 565-0871, Japan

Applied Physics Express

https://doi.org/10.7567/APEX.11.061501

We performed first-principle calculations to

investigate the effect of incorporation of N atoms

into Al2O3 gate dielectrics. Our calculations show

that the defect levels generated by VO in Al2O3 are

the origin of the stress-induced gate leakage current

and that VOVAl complexes in Al2O3 cause negative

fixed charge. We revealed that the incorporation of N

atoms into Al2O3 eliminates the VO defect levels,

reducing the stress-induced gate leakage current.

Moreover, this suppresses the formation of

negatively charged VOVAl complexes. Therefore,

GaNEX | III-N Technology Newsletter No. 65 | 12

AlON can reduce both stress-induced gate leakage

current and negative fixed charge in wide-bandgap-

semiconductor MOSFETs.

Device and System-level Transient Analysis in A

Modular Designed Sub-MW EV Fast Charging Station

Using Hybrid GaN HEMTs+Si MOSFETs GaN Systems Inc, 1145 Innovation Drive, Ottawa ON,

Canada K2K 3G8

Electrical and Computer Engineering, University of

Michigan-Dearborn, 4901 Evergreen Rd, Dearborn, MI,

USA

IEEE Journal of Emerging and Selected Topics in Power

Electronics

https://doi.org/10.1109/JESTPE.2018.2834483

Though wide-bandgap (WBG) devices are believed as

the promising candidate for next-generation high-

efficiency and high-power-density power electronic

converters, two major challenges remain as high cost

(more than twice of Si) and less options (the

maximum power rating for GaN is only 650V/60A).

From the device level, paralleling GaN with Si can

inherit merits of both GaN devices (superior

switching performance) and Si devices (affordable

with high-current capability). In this paper, firstly GaN

HEMTs are paralleled to a TO-247 Si MOSFET to form

a high-current switching cell for a 6.6kW EV charging

module. A time delay is added between switch gate

signals to make GaN endure the switching loss and Si

conduct majority of the static current. Critical

dynamic behaviors such as the current overshoot to

the GaN, current distribution during the dead time,

and voltage spike during the turn-off caused by

parasitics are comprehensively discussed. From the

system level, series connecting the input and

paralleling output of multiple such modules yield a

sub-MW EV charging station. Once one phase drops,

the related phase can act as the active filter while

other two phases still work to charge the battery.

Suppression of the Backgating Effect of

Enhancement-mode p-GaN HEMTs on 200 mm GaN-

on-SOI for Monolithic Integration Imec, 3001 Leuven, Belgium

Department of Electrical Engineering (ESAT), KU Leuven,

3001 Leuven, Belgium

Okmetic Oy, FI-01301 Vantaa, Finland

IEEE Electron Device Letters

https://doi.org/10.1109/LED.2018.2833883

The backgating effect on trench-isolated

enhancement- mode p-GaN devices fabricated on

200 mm GaN-on-SOI was investigated. We show that,

to minimize the backgating effect in the

monolithically integrated half-bridge, the sources of

both the low side and high side need to be connected

to their respective fully-isolated Si(111) device layers

to keep the substrates and the sources at

equipotential.

Etched Al0.32Ga0.68N/GaN HEMTs with high output

current and breakdown voltage (>600 V) Key Laboratory of the Ministry of Education for Wide

Band-Gap Semiconductor Materials and Devices, School of

Microelectronics, Xidian University, People's Republic of

China

IET Micro & Nano Letters

https://doi.org/10.1049/mnl.2017.0651

By etching the AlGaN layer close to the gate edge of

the drain side, the novel AlGaN/GaN high-electron-

mobility transistor with the etched AlGaN epitaxial

layer (etched AlGaN/GaN high-electron-mobility

transistors, HEMTs) is proposed in this work with the

high-resistance GaN buffer layer. The relationship

between the 2D electron gas (2DEG) concentration

and the thickness of the AlGaN layer has been

explored. The 2DEG density under the etched barrier

is reduced to optimise the surface electric field and

mobility of 2DEG. The electric field is reshaped by the

etched AlGaN layer, featuring an extra electric field

peak far away from the gate edge. The electric field

peak near the gate is decreased effectively because

of the extra electric field peak, which therefore

improves the breakdown voltage (BV). The mobility

of 2DEG is increased because of the low 2DEG

concentration, which improves the output current

(IDS). The experimental BV is improved from 152 V

for the conventional structure to 620 V for etched

AlGaN/GaN HEMTs because of the optimised surface

electric field. The maximum output current (Imax) is

increased from 381 to 478 mA/mm. The trade-off

between the BV and Ron,sphas been improved to

break the silicon limit. It is concluded that the gate-

GaNEX | III-N Technology Newsletter No. 65 | 13

edge etching technique can significantly increase

both BV and IDS for AlGaN/GaN HEMTs.

Reverse-Blocking Normally-Off GaN Double-Channel

MOS-HEMT with Low Reverse Leakage Current and

Low ON-State Resistance Department of Electronic and Computer Engineering, The

Hong Kong University of Science and Technology, Kowloon,

Hong Kong and HKUST Shenzhen Research Institute,

Shenzhen, 518000, CHINA

IEEE Electron Device Letters

https://doi.org/10.1109/LED.2018.2832180

A MOS field plate protected Schottky-drain (gated

Schottky-drain) is successfully integrated on a double-

channel AlGaN/GaN MOS-HEMT to provide reverse

blocking capability. The leakage suppression MOS

field plate is deployed on the etched upper GaN

channel layer after a barrier fully-recess process,

leading to a low reverse OFF-state leakage current of

−20 nA/mm (at −100 V). The drain metal is deployed

adjacent to the MOS field plate, contacting the upper

MOS-channel and lower heterojunction channel from

the sidewall. A metal-2DEG Schottky contact with a

low turn-on voltage of 0.5 V is achieved. Since the

lower channel (below the MOS field plate) is

separated from the etched surface of upper GaN

channel layer, a high-conductivity MOS-gated

channel with a sheet resistance of 806 Ω/Square is

obtained. The device exhibits a threshold voltage of

+0.6 V (at 10 μA/mm and +1.9 V from linear

extrapolation) and an ON-resistance of ~18 Ω·mm.

Besides, a high forward (and reverse) breakdown

voltage of 790 V (and −656 V, all at 10 μA/mm) is

achieved.

Development of GaN Vertical Trench-MOSFET With

MBE Regrown Channel School of Electrical and Computer Engineering, Cornell

University, Ithaca, NY 14850 USA

IQE RF LLC, Somerset, NJ 08873 USA

Qorvo, Inc., Richardson, TX 75080 USA

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2829125

GaN vertical trench-MOSFETs incorporating

molecular beam epitaxy (MBE) regrown channel are

developed and investigated. The channel regrowth by

MBE prevents repassivation of the p-type GaN body

while promising higher channel mobility. Two

different designs of the lateral portion of the regrown

channel are compared: without or with an n⁺-GaN

buried layer. Without an n⁺ buried layer, a

respectable 600-V breakdown voltage (BV) is

measured in the absence of edge termination,

indicating a decent critical field strength (>1.6

MV/cm) of the regrown channel. However, the ON-

resistance is limited by the highly resistive lateral

channel due to Mg incorporation. With an n⁺ buried

layer, the limitation is removed. Excellent ON-current

of 130 mA/mm and ON-resistivity of 6.4 mΩ· cm² are

demonstrated. The BV is limited by high source-drain

leakage current from the channel due to drain-

induced barrier lowering (DIBL) effect. Device analysis

together with TCAD simulations points out the major

cause for the DIBL effect: the presence of interface

charge beyond a critical value (~6x10¹² cm⁻²) at the

regrowth interface on etched sidewalls. This paper

provides valuable insights into the design of GaN

vertical trench-MOSFET with a regrown channel,

where simultaneous achievement of low ON-

resistivity and high BV is expected in devices with

reduced interface charge density and improved

channel design to eliminate DIBL.

Threshold Voltage Instability in p-GaN Gate

AlGaN/GaN HFETs Dipartimento di Ingegneria dell'Informazione, Università di

Pisa, 56126 Pisa, Italy

Infineon Technologies Austria AG, 9500 Villach, Austria

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2828702

We investigate the impact of the gate contact on the

threshold voltage stability in p-GaN gate AlGaN/GaN

heterojunction field-effect transistors with double

pulse measurements on the p-GaN gate devices and

device simulations. We find that, under gate stress, in

the case of high-leakage Schottky contact, a negative

threshold voltage shift results from hole

accumulation in the p-GaN region. Conversely, in the

case of low-leakage Schottky contact, hole depletion

in the p-GaN region gives rise to a positive threshold

voltage shift. More generally, we show that an

imbalance between the hole tunneling current

through the Schottky barrier and the thermionic

GaNEX | III-N Technology Newsletter No. 65 | 14

current across the AlGaN barrier results in a variation

of the total charge stored in the p-GaN region, which

in turn is responsible for the observed threshold

voltage shift. Finally, we present a simplified

equivalent circuit model for the p-GaN gate module.

AlGaN-Channel Gate Injection Transistor on Silicon

Substrate with Adjustable 4 V to 7 V Threshold

Voltage and 1.3 kV Breakdown Voltage Key Laboratory of Wide Band Gap Semiconductor

Materials and Devices, School of Microelectronics, Xidian

University, Xi’an 710071, People’s Republic of China

IEEE Electron Device Letters

https://doi.org/10.1109/LED.2018.2838542

We report on demonstrating the first Al0.05Ga0.95N-

channel enhancement-mode (E-mode) p-GaN gate

injection transistors (GITs) with an adjustable

threshold voltage (VT) of 4 V to 7 V by controlling the

number of the source connected p-GaN bridges. To

the best of our knowledge, it is the highest VT

reported in p-GaN gate injection transistors.

Comparing to GaN channel, the Al0.05Ga0.95N

channel is used to minimize the polarization

difference between channel layer and Al0.15Ga0.85N

barrier layer and also increase the maximum

affordable electric field of the channel so as to

increase the VT and breakdown voltage. Combing

with the 4.3 μm thick buffer layer, E-mode GITs

demonstrate an off-state breakdown voltage of 662

V, 770 V, 1034 V and 1315 V at a gate-to-drain

spacing of 5 μm, 7 μm, 11 μm and 19 μm

respectively, showing the great promise of the AlGaN

channel E-Mode GITs for future power electronics

applications.

Impact of Substrate Resistivity on the Vertical

Leakage, Breakdown, and Trapping in GaN-on-Si E-

Mode HEMTs Department of information engineering, University of

Padova, 35131 Padova, Italy

IMEC, 3001 Louvain, Belgium

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2830107

This paper presents an extensive investigation of the

impact of the resistivity of the silicon substrate on the

vertical leakage and charge trapping in 200 V GaN-on-

Si enhancement-mode high-electron mobility

transistors. Three wafers having different substrate

resistivities were submitted to combined DC

characterization, step-stress experiments, and

electroluminescence (EL) analysis. The results

described within this paper demonstrate that: 1) the

use of a highly resistive silicon substrate can increase

the vertical breakdown voltage of the transistors, due

to the fact that the voltage drop on the GaN buffer is

mitigated by the partial depletion of the substrate

(this latter causes a plateau region in the drain to

substrate I-V characteristic) and 2) highly resistive

substrate results in stronger trapping effects, due to

the capacitance of the depleted substrate and the

resulting backgating effects. The results described

within this paper indicate that the choice of the

resistivity of the substrate is the result of a tradeoff

between high breakdown voltage (that could be in

principle achieved through a highly resistive

substrate) and the minimization of trapping

processes (which can be hardly obtained with a

resistive substrate).

Improving the Third Quadrant Operation of

Superjunction MOSFETs by Using the Cascode

Configuration Ingenieria Electrica, Electronica, de Computadores y

Sistemas, University of Oviedo, Gijon Spain 33204

Department of Electrical Engineering, Universidad de

Oviedo, 16763 Gijon, Asturias Spain 33204

R&D, ON Semiconductor, Oudenaarde, Saitmama Belgium

IEEE Transactions on Power Electronics

https://doi.org/10.1109/TPEL.2018.2837747

In this paper, the third quadrant behavior of a High-

Voltage (HV) Superjunction MOSFET (SJ-FET) in

Cascode Configuration (CC) with a Low-Voltage silicon

MOSFET (LV-FET) is deeply studied by means of an

analytical model and experimental data. The third

quadrant dynamic behavior of the SJ-CCs is compared

to the standalone counterparts by evaluating their

reverse recovery time (tRR), reverse recovery peak

current (IRRM) and reverse recovery charge (QRR).

Analytical model and experimental results show that

the SJ-CC avoids or mitigates the activation of the SJ-

FET body-diode during the third quadrant operation.

As a consequence, the SJ-CC strongly improves the

GaNEX | III-N Technology Newsletter No. 65 | 15

widely used Figure-of-Merit (FoM) RON⋅;QRR, which

considers the on-state resistance of the transistors

(RON). In addition, the results obtained using a SJ-CC

are similar or better than the achieved by SJ-FETs

with enhanced reverse recovery (i.e., irradiated SJ-

FETs). This paper also includes a comparison with

commercial wide bandgap switches, concluding that

the RON⋅;QRR value provided by the SJ-CC is around

eight times higher than the provided by a commercial

GaN cascode.

Low-Dispersion, High-Voltage, Low-Leakage GaN

HEMTs on Native GaN Substrates Institut für Mikroelektronik Stuttgart, 70569 Stuttgart,

Germany

Center for Energy Research, Institute of Technical Physics

and Materials Science, Hungarian Academy of Sciences,

1245 Budapest, Hungary

Azur Space Solar Power GmbH, 74072 Heilbronn, Germany

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2832250

In this paper, the advantages of GaN high electron

mobility transistors (HEMTs) grown on native GaN

over GaN/Si or GaN/sapphire substrates are

investigated and correlated with epitaxial material

quality. Transmission electron microscopy plan-view

and cross-sectional analyses of GaN/GaN reveal

dislocation densities below 1 x 10⁶ cm⁻², which is at

least three orders of magnitude lower than that of

GaN/Si or GaN/sapphire. In the case of GaN/Si, the

dislocations not only originate from the

substrate/nucleation layer interface, but also the

strain relief and isolation buffer stacks are main

contributors to the dislocation density. GaN/GaN

HEMTs show superior electrical and thermal

performance and feature three orders of magnitude

lower OFF-state leakage. The current collapse (also

referred to as current dispersion or RON-increase)

after stress bias is less than 15% compared with 50%

in the case of GaN/Si. A 2% drop of the ON-state

current due to self-heating in dc operation when

compared with 13% and 16% for GaN/Si and

GaN/sapphire, respectively. The GaN/Si thermal

performance becomes comparable to that of

GaN/GaN only after substrate removal. Therefore,

GaN/GaN provides high ON-state current, low OFF-

state leakage current, minimal current collapse, and

enhanced thermal power dissipation capability at the

same time, which can directly be correlated with the

absence of high dislocation density.

High performance vertical GaN-on-GaN p-n power

diodes with hydrogen-plasma based edge

termination School of Electrical, Computer and Energy Engineering,

Arizona State University, Tempe, AZ, 85287 USA

IEEE Electron Device Letters

https://doi.org/10.1109/LED.2018.2837625

This letter reports the first implementation of a

hydrogen-plasma based edge termination technique

(HPET) in vertical GaN p-n power diodes grown on

bulk GaN substrates using metalorganic chemical

vapor deposition (MOCVD). The device with a 9-μm-

thick drift layer exhibited a high breakdown voltage

(Vbd) of 1.57 kV, a low on-resistance (Ron) of 0.45

mΩ·cm2(or 0.70 mΩ·cm2 with current spreading

considered) and a high Baliga’s figure-of-merit (V2

bd/Ron) of 5.5 GW/cm2 (or 3.6 GW/cm2) without

passivation or field plate, which are close to the

theoretical limit of GaN. This technique enabled a

significant reduction in leakage current (~ 106 times

at − 300V) and a huge enhancement in Vbd (from ~

300 V to 1.57 kV). Furthermore, the device showed

good forward characteristics with a turn-on voltage

of 3.5 V, an on-current of ~ 2 kA/cm2 ( or 1.3

kA/cm2), an on/off ratio of ~ 109, and an ideality

factor of 1.4. This work shows the HPET can serve as

an effective, low-cost and easy-to-implement edge

termination technique for high voltage and high

power GaN p-n power diodes.

Total photoelectron yield spectroscopy of energy

distribution of electronic states density at GaN

surface and SiO2/GaN interface Graduate School of Engineering, Nagoya University,

Nagoya 464-8603, Japan

Institute for Advanced Research, Nagoya University,

Nagoya 464-8601, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06KA08

The energy distribution of the electronic state density

of wet-cleaned epitaxial GaN surfaces and SiO2/GaN

GaNEX | III-N Technology Newsletter No. 65 | 16

structures has been studied by total photoelectron

yield spectroscopy (PYS). By X-ray photoelectron

spectroscopy (XPS) analysis, the energy band diagram

for a wet-cleaned epitaxial GaN surface such as the

energy level of the valence band top and electron

affinity has been determined to obtain a better

understanding of the measured PYS signals. The

electronic state density of GaN surface with different

carrier concentrations in the energy region

corresponding to the GaN bandgap has been

evaluated. Also, the interface defect state density of

SiO2/GaN structures was also estimated by not only

PYS analysis but also capacitance–voltage (C–V)

characteristics. We have demonstrated that PYS

analysis enables the evaluation of defect state

density filled with electrons at the SiO2/GaN

interface in the energy region corresponding to the

GaN midgap, which is difficult to estimate by C–V

measurement of MOS capacitors.

Enhancement of breakdown voltage for fully-

vertical GaN-on-Si p-n diode by using strained layer

superlattice as drift layer Research Center for Nano-Devices and Advanced

Materials, Nagoya Institute of Technology, Nagoya 466-

8555, Japan

Semiconductor Science and Technology

https://doi.org/10.1088/1361-6641/aabb8f

We have demonstrated a vertical GaN-on-Si p-n

diode with breakdown voltage (BV) as high as 839 V

by using a low Si-doped strained layer superlattice

(SLS). The p-n vertical diode fabricated by using the

n−-SLS layer as a part of the drift layer showed a

remarkable enhancement in BV, when compared

with the conventional n−-GaN drift layer of similar

thickness. The vertical GaN-on-Si p-n diodes with 2.3

μm-thick n−-GaN drift layer and 3.0 μm-thick n−-SLS

layer exhibited a differential on-resistance of 4.0 Ω

centerdot cm2 and a BV of 839 V.

Drain current enhancement induced by hole

injection from gate of 600-V-class normally off gate

injection transistor under high temperature

conditions up to 200 °C Graduate School of Engineering, Tohoku University, Sendai

980-8579, Japan

Center for Innovative Integrated Electronic Systems,

Tohoku University, Sendai 980-0845, Japan

Panasonic Corporation, Kadoma, Osaka 571-8501, Japan

NEDO under the Strategic Development of Energy Saving

Innovative Technology Development Project, Sendai 980-

8579, Japan

JST-ACCEL, Sendai 980-8579, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06KC03

In this paper, the current–voltage (I–V) characteristics

of a 600-V-class normally off GaN gate injection

transistor (GIT) from 25 to 200 °C are analyzed, and it

is revealed that the drain current of the GIT increases

during high-temperature operation. It is found that

the maximum drain current (I dmax) of the GIT is 86%

higher than that of a conventional 600-V-class

normally off GaN metal insulator semiconductor

hetero-FET (MIS-HFET) at 150 °C, whereas the GIT

obtains 56% I dmax even at 200 °C. Moreover, the

mechanism of the drain current increase of the GIT is

clarified by examining the relationship between the

temperature dependence of the I–V characteristics of

the GIT and the gate hole injection effect determined

from the shift of the second transconductance (g m)

peak of the g m–V g characteristic. From the above,

the GIT is a promising device with enough drivability

for future power switching applications even under

high-temperature conditions.

Energy band structure and electrical properties of

Ga-oxide/GaN interface formed by remote oxygen

plasma Graduate School of Engineering, Nagoya University,

Nagoya 464-8603, Japan

National Institute of Advanced Industrial Science and

Technology (AIST), GaN Advanced Device Open Innovation

Laboratory (GaN-OIL), Nagoya 464-8603, Japan

Nagoya University Institute of Materials and Systems for

Sustainability (IMaSS), Nagoya 464-8603, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06KA05

GaNEX | III-N Technology Newsletter No. 65 | 17

The energy band structure of a Ga-oxide/GaN

structure formed by remote oxygen plasma exposure

and the electrical interface properties of the GaN

metal–oxide–semiconductor (MOS) capacitors with

the SiO2/Ga-oxide/GaN structures with

postdeposition annealing (PDA) at various

temperatures have been investigated. Reflection

high-energy electron diffraction and X-ray

photoelectron spectroscopy clarified that the formed

Ga-oxide layer is neither a single nor polycrystalline

phase with high crystallinity. We found that the

energy band offsets at the conduction band minimum

and at the valence band maximum between the Ga-

oxide layer and the GaN surface were 0.4 and 1.2 ±

0.2 eV, respectively. Furthermore, capacitance–

voltage (C–V) characteristics revealed that the

interface trap density (D it) is lower than the

evaluation limit of Terman method without

depending on the PDA temperatures, and that the

SiO2/Ga-oxide stack can work as a protection layer to

maintain the low D it, avoiding the significant

decomposition of GaN at the high PDA temperature

of 800 °C.

Physical and electrical characterizations of

AlGaN/GaN MOS gate stacks with AlGaN surface

oxidation treatment Graduate School of Engineering, Osaka University, Suita,

Osaka 565-0871, Japan

Panasonic Corporation, Nagaokakyo, Kyoto 617-8520,

Japan

Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06KA07

The impacts of inserting ultrathin oxides into

insulator/AlGaN interfaces on their electrical

properties were investigated to develop advanced

AlGaN/GaN metal–oxide–semiconductor (MOS) gate

stacks. For this purpose, the initial thermal oxidation

of AlGaN surfaces in oxygen ambient was

systematically studied by synchrotron radiation X-ray

photoelectron spectroscopy (SR-XPS) and atomic

force microscopy (AFM). Our physical

characterizations revealed that, when compared with

GaN surfaces, aluminum addition promotes the initial

oxidation of AlGaN surfaces at temperatures of

around 400 °C, followed by smaller grain growth

above 850 °C. Electrical measurements of AlGaN/GaN

MOS capacitors also showed that, although excessive

oxidation treatment of AlGaN surfaces over around

700 °C has an adverse effect, interface passivation

with the initial oxidation of the AlGaN surfaces at

temperatures ranging from 400 to 500 °C was proven

to be beneficial for fabricating high-quality

AlGaN/GaN MOS gate stacks.

N-Polar GaN HEMTs Exhibiting Record Breakdown

Voltage Over 2000 V and Low Dynamic On-

Resistance Department of Electrical and Computer Engineering,

University of California Santa Barbara, Santa Barbara, CA

93106 USA

Transphorm, Inc., 115 Castilian Dr, Goleta, CA 93117 USA

IEEE Electron Device Letters

https://doi.org/10.1109/LED.2018.2834939

Nitrogen polar GaN high-electron-mobility transistors

(HEMT) targeting high-voltage switching applications

were fabricated on epi-layers grown by metal-organic

chemical vapor deposition (MOCVD) on sapphire

substrates. Devices demonstrated a combination of

high breakdown voltage and low dynamic on-

resistance. Breakdown voltages of over 2000 V were

observed on transistors with LG = 1 μm, LGS = 1 μm,

and LGD = 28 μm. These devices had a drain current

density of ~ 575 mA/mm at VGS = 1 V, and the

specific on-resistance (active-area) was 4 mΩ·cm2 (10

Ω·mm). Dynamic on-resistance (Ron) was

characterized 5 μs after the device was turned on,

with up to 575 V off-state stress. At VDS, Q = 575 V,

the dynamic Ron was ~1.4 times the static Ron (40%

increase). These transistors showed an ultra-low

dynamic Ron of ~5% when measured at 450 V stress.

As one of the first demonstrations of N-Polar GaN

HEMTs for power switching applications, the devices

discussed in this letter achieve excellent Vbr and

dynamic Ron performance comparable to (and in

most cases better than) the state-of-the-art Ga-Polar

GaN HEMTs reported in the literature.

GaNEX | III-N Technology Newsletter No. 65 | 18

An Analytical Investigation on the Charge

Distribution and Gate Control in the Normally-Off

GaN Double-Channel MOS-HEMT HKUST Shenzhen Research Institute, Shenzhen 518000,

China

Department of Electronic and Computer Engineering, The

Hong Kong University of Science and Technology, Hong

Kong

Department of Industrial and Systems Engineering, The

Hong Kong Polytechnic University, Hong Kong

College of Optoelectronic Engineering, Shenzhen

University, Shenzhen 518000, China

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2831246

A systematic analytical investigation of the charge

distribution and gate control of the normally-off GaN

double-channel MOS-HEMT (DC-MOS-HEMT) is

presented in this paper. Compared to conventional

GaN MOS-HEMT, the DC-MOS-HEMT features a thin

AlN insertion layer (AlN-ISL) below the original two

dimensional electron gas (2DEG) channel, thus

forming a second channel at the interface between

AlN-ISL and the underlying GaN. This paper reveals

the impact of the AlN-ISL on the 2DEG distribution

and the gate control of the channels. The sensitivity

of Vth against the recess depth is also analytically

studied and is found to be nearly independent of the

recess depth as long as the recess is terminated in

the upper channel layer. The analytical results are

well supported by numerical device simulations, and

the physical mechanisms behind these findings are

explained along with the analytical investigations.

A study of temperature dependent current–voltage

(I–V–T) characteristics in Ni/sol–gel β-Ga2O3/n-GaN

structure Department of Electrical and Computer Engineering,

University of California, Davis, USA

Department of Materials Science and Engineering,

University of California, Davis, USA

Journal of Materials Science: Materials in Electronics

https://doi.org/10.1007/s10854-018-9213-y

β-Ga2O3 thin films were grown on n-type GaN

substrates using the sol–gel method. The forward-

biased temperature dependent current–voltage (I–V–

T) characteristics of Ni/β-Ga2O3/GaN structure have

been investigated in the temperature range of 298–

473 K. The apparent barrier height ( ϕap ) increased

while the ideality factor (n) decreased with the

increase in temperature. Such a temperature

dependent behavior of ϕap and n was explained by

the inhomogeneity of ϕap , which obeyed Gaussian

distribution with zero-bias mean barrier height (

ϕ¯B0 ) of 1.02 ± 0.02 eV and standard deviation ( σs0

) of 153 ± 0.04 mV. Subsequently, ϕ¯B0 and

Richardson constant A* were obtained from the

slope and intercept of the modified Richardson plot

as 0.99 ± 0.01 e V and 67.2 A cm−2 K−2, respectively.

The ϕ¯B0 obtained from the modified Richardson

plot was in good agreement with the theoretical

value calculated from the work function of Ni and

electron affinity of β-Ga2O3. The I–V–T

characteristics of Ni/β-Ga2O3/GaN MOS structures

can be successfully explained by the thermionic

emission theory with a single Gaussian distribution of

the barrier height.

Improvement of breakdown voltage of vertical GaN

p–n junction diode with Ga2O3 passivated by

sputtering Advanced Technology Research Laboratories, Idemitsu

Kosan Co., Ltd., Sodegaura, Chiba 299-0293, Japan

Institute of Materials and Systems for Sustainability,

Nagoya University, Nagoya 464-8603, Japan

Akasaki Research Center, Nagoya University, Nagoya 464-

0814, Japan

Venture Business Laboratory, Nagoya University, Nagoya

464-0814, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.070302

This article describes a new passivation process of Ga2O3, which consists by sputtering, for a vertical GaN p–n junction diode on a free-standing GaN substrate with a field-plate (FP) structure. We demonstrated reduced plasma damage during the sputtering process by cure annealing, and succeeded in improving the breakdown voltage (V B) to −550 V with the FP, compared with V B of −200 V without the FP. Ga2O3 is a suitable material for the FP because its dielectric constant is similar to that of GaN and it is more easily etched than Al2O3, which is used as a conventional insulator.

GaNEX | III-N Technology Newsletter No. 65 | 19

GROUP 4 - Advanced Electronics and RF Group leader: Jean-Claude Dejaeger (IEMN)

Information selected by Jean-Claude Dejaeger (IEMN) and Yvon Cordier (CRHEA-CNRS)

SiO2/AlON stacked gate dielectrics for AlGaN/GaN

MOS heterojunction field-effect transistors Graduate School of Engineering, Osaka University, Suita,

Osaka 565-0871, Japan

Panasonic Corporation, Nagaokakyo, Kyoto 617-8520,

Japan

Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06KA03

Stacked gate dielectrics consisting of wide bandgap

SiO2 insulators and thin aluminum oxynitride (AlON)

interlayers were systematically investigated in order

to improve the performance and reliability of

AlGaN/GaN metal–oxide–semiconductor (MOS)

devices. A significantly reduced gate leakage current

compared with that in a single AlON layer was

achieved with these structures, while maintaining the

superior thermal stability and electrical properties of

the oxynitride/AlGaN interface. Consequently,

distinct advantages in terms of the reliability of the

gate dielectrics, such as an improved immunity

against electron injection and an increased dielectric

breakdown field, were demonstrated for AlGaN/GaN

MOS capacitors with optimized stacked structures

having a 3.3-nm-thick AlON interlayer.

Implementation of atomic layer deposition-based

AlON gate dielectrics in AlGaN/GaN MOS structure

and its physical and electrical properties Graduate School of Engineering, Osaka University, Suita,

Osaka 565-0871, Japan

Panasonic Corporation, Nagaokakyo, Kyoto 617-8520,

Japan

Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.06KA02

Alumina incorporating nitrogen (aluminum

oxynitride; AlON) for immunity against charge

injection was grown on a AlGaN/GaN substrate

through the repeated atomic layer deposition (ALD)

of AlN layers and in situ oxidation in ozone (O3)

ambient under optimized conditions. The nitrogen

distribution was uniform in the depth direction, the

composition was controllable over a wide range (0.5–

32%), and the thickness could be precisely controlled.

Physical analysis based on synchrotron radiation X-

ray photoelectron spectroscopy (SR-XPS) revealed

that harmful intermixing at the insulator/AlGaN

interface causing Ga out-diffusion in the gate stack

was effectively suppressed by this method.

AlON/AlGaN/GaN MOS capacitors were fabricated,

and they had excellent electrical properties and

immunity against electrical stressing as a result of the

improved interface stability.

A Compact Ultrabroadband Stacked Traveling-Wave

GaN on Si Power Amplifier Chengdu Ganide Technology, Chengdu 610073, China

College of Physics and Electronic Information Engineer,

Qinghai University for Nationalities, Xining 810007, China

Tianjin Key Laboratory of Imaging and Sensing

Microelectronic Technology, School of Electronic

Information Engineering, Tianjin University, Tianjin

300072, China

IEEE Transactions on Microwave Theory and Techniques

https://doi.org/10.1109/TMTT.2018.2828434

The design and implementation of a GaN stacked

distributed 2-19GHz monolithic microwave

integrated circuit (MMIC) power amplifier (PA) is

presented in this paper. The PA architecture uses six

distributed cells, each containing a stack of three

transistors. A design method that employs

capacitance compensation is presented and applied

to a 5-10-W PA design for the 2-19-GHz range in a

100-nm GaN on Si technology. The resulting

measured performance at 28-V supply shows a gain

flatness of 20.5 ± 1.5 dB, with an output power of

37.4-40.9 dBm and corresponding poweradded

efficiency of 22%-49% over the entire frequency

range. To the best of the authors' knowledge, this is

the first demonstration of a GaN on Si stacked

distributed MMIC PA, with a die size of 2.8 x 1.7 mm²

GaNEX | III-N Technology Newsletter No. 65 | 20

and with a maximum power density of 2.58 W/mm²

over chip area.

Support Vector Regression-Based Behavioral

Modeling Technique for RF Power Transistors Key Laboratory of RF Circuit and System, Ministry of

Education, College of Electronics and Information,

Hangzhou Dianzi University, Hangzhou, China

RF and Microwave Research Group, University College

Dublin, Ireland

State Key Laboratory of Millimeter Waves, School of

Information Science and Engineering, Southeast University,

Nanjing, China

IEEE Microwave and Wireless Components Letters

https://doi.org/10.1109/LMWC.2018.2819427

A nonlinear behavioral modeling technique, based on

support vector regression (SVR), is presented in this

letter. As an advanced machine-learning technique,

the SVR method provides a more effective way to

determine the optimal model when compared with

the more traditional modeling approaches based on

artificial neural network (ANN) techniques. The

proposed technique can overcome the well-known

overfitting issue often associated with ANNs. In this

letter, the basic theory of the proposed SVR modeling

method is provided, along with details on model

implementation in the context of RF transistor

devices. Both simulation and experimental test

examples for a 10-W gallium nitride (GaN) transistor

are provided, revealing that the new modeling

methodology provides a more efficient and robust

prediction throughout the Smith chart when

compared with ANNs, with the latest results showing

excellent model fidelity at both the fundamental and

at the second harmonic.

Electron Trapping in Extended Defects in Microwave

AlGaN/GaN HEMTs With Carbon-Doped Buffers Department of Microtechnology and Nanoscience,

Chalmers University of Technology, SE-412 96 Gothenburg,

Sweden

SweGaN AB, SE-583 30 Linköping, Sweden

Department of Physics, Chemistry and Biology (IFM),

Science Institute, University of Iceland, IS-107 Reykjavik,

Iceland

Department of Physics, Chemistry and Biology (IFM),

Linköping University, SE-58183 Linköping, Sweden

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2828410

This paper investigates AlGaN/GaN high-electron

mobility transistors (HEMTs) fabricated on

epistructures with carbon (C)-doped buffers.

Metalorganic chemical vapor deposition is used to

grow two C-doped structures with different doping

profiles, using growth parameters to change the C

incorporation. The C concentration is low enough to

result in n-type GaN. Reference devices are also

fabricated on a structure using iron (Fe) as dopant, to

exclude any process related variations and provide a

relevant benchmark. All devices exhibit similar dc

performance. However, pulsed I-V measurements

show extensive dispersion in the C-doped devices,

with values of dynamic RON 3-4 times larger than in

the dc case. Due to the extensive trapping, the

devices with C-doped buffers can only supply about

half the output power of the Fe-doped sample, 2.5

W/mm compared to 4.8 W/mm at 10 GHz. In drain

current transient measurements, the trap filling time

is varied, finding large prevalence of trapping at

dislocations for the C-doped samples. Clusters of C

around the dislocations are suggested to be the main

cause for the increased dispersion.

Planar Nanostrip-Channel Al2O3/InAlN/GaN

MISHEMTs on Si with Improved Linearity School of Electrical & Electronic Engineering, Nanyang

Technological University, 50 Nanyang Ave 639798

Singapore

Low Energy Electronic Systems, Singapore-MIT Alliance of

Research and Technology, 1 CREATE Way 138602

Singapore

Temasek Laboratories @ NTU, Nanyang Technological

University, Singapore 637553

Microsystems Technology Laboratories, Massachusetts

Institute of Technology, Cambridge, MA 02139 USA

IEEE Electron Device Letters

https://doi.org/10.1109/LED.2018.2837886

In this work, a 100 nm-gate Al2O3/InAlN/GaN metal-

insulator-semiconductor high electron mobility

transistor (MISHEMT) with a planar nanostrip-

channel was fabricated on a Si substrate and its DC,

small-signal RF and two-tone intermodulation

characteristics were measured. The use of a planar

nanostrip-channel and MIS structure allows these

GaNEX | III-N Technology Newsletter No. 65 | 21

devices to have close to 10 dB better intermodulation

distortion (IMD) than traditional InAlN/GaN high

electron mobility transistors (HEMTs). In addition, the

GaN planar nanostrip-channel MISHEMT shows five

orders of magnitude lower gate current Ig, 30%

higher current drivability and much improved gm and

fT gate voltage swing than a planar nanostrip-channel

GaN HEMT with a Schottky-gate. This allows the

planar nanostrip-channel GaN MISHEMT to be able to

operate at higher input gate voltage (more than Vg=

+4 V) and achieve higher output current with better

linearity performance.

High-speed FP GaN HEMT with fT/fMAX of 95/200

GHz HRL Laboratory, LLC, USA

Electronics Letters

https://doi.org/10.1049/el.2018.0417

Highly scaled 90 nm gate-length field-plated (FP)

aluminium gallium nitride (GaN)/GaN high electron

mobility transistors (HEMTs) with a record current

gain cut-off frequency (fT) of 95 GHz and maximum

oscillation frequency (fMAX) of 200 GHz is reported.

Both lateral scaling of source-to-drain distance to 1

μm and vertical scaling of gate-to-channel depth to

90 nm, along with n+-GaN ohmic contact, were

utilised to minimise the parasitics, and the gate-

length scaling of FP GaN HEMTs down to 90 nm gate

length was demonstrated with a record speed

performance for the first time. The small-signal

model predicts that the fT is still dominated by the

gate-to-source capacitance, implying that the speed

performance of FP GaN HEMTs can further improve.

An Analytical Investigation on the Charge

Distribution and Gate Control in the Normally-Off

GaN Double-Channel MOS-HEMT HKUST Shenzhen Research Institute, Shenzhen 518000,

China

Department of Electronic and Computer Engineering, The

Hong Kong University of Science and Technology, Hong

Kong

Department of Industrial and Systems Engineering, The

Hong Kong Polytechnic University, Hong Kong

College of Optoelectronic Engineering, Shenzhen

University, Shenzhen 518000, China

IEEE Transactions on Electron Devices

https://doi.org/10.1109/TED.2018.2831246

A systematic analytical investigation of the charge

distribution and gate control of the normally-off GaN

double-channel MOS-HEMT (DC-MOS-HEMT) is

presented in this paper. Compared to conventional

GaN MOS-HEMT, the DC-MOS-HEMT features a thin

AlN insertion layer (AlN-ISL) below the original two

dimensional electron gas (2DEG) channel, thus

forming a second channel at the interface between

AlN-ISL and the underlying GaN. This paper reveals

the impact of the AlN-ISL on the 2DEG distribution

and the gate control of the channels. The sensitivity

of Vth against the recess depth is also analytically

studied and is found to be nearly independent of the

recess depth as long as the recess is terminated in

the upper channel layer. The analytical results are

well supported by numerical device simulations, and

the physical mechanisms behind these findings are

explained along with the analytical investigations.

Observation of Hot-Electron and Impact-Ionization

in N-polar GaN MIS-HEMTs University of Padova, Department of Information

Engineering

University of California, Santa Barbara, Department of

Electrical and Computer Engineering

IEEE Electron Device Letters

https://doi.org/10.1109/LED.2018.2835517

This paper reports on the observation of hot-electron

and impact ionization mechanisms in N-polar GaN-

based MIS-HEMTs designed for high frequency (RF)

operation. Thanks to the extremely low gate leakage

of such devices, we were able to demonstrate – for

the first time – a correlation between

electroluminescence (EL) and gate current in the

semi-on state. In the semi-on state, (i) the devices

show a non-monotonic, bell-shaped behavior of the

EL-vs-VGS and of the IG-vs-VGS characteristics, and

(ii) the intensity of the EL signal is proportional to the

IGxID product. The results are experimental evidence

for impact ionization: the related mechanisms are

described in detail in the paper.

GaNEX | III-N Technology Newsletter No. 65 | 22

An analytic current-voltage model for quasi-ballistic

III-nitride high electron mobility transistors Department of Electrical and Computer Engineering, New

York University, Brooklyn, New York 11201, USA

Journal of Applied Physics

https://doi.org/10.1063/1.5025339

We present an analytic model to describe the DC

current-voltage (I-V) relationship in scaled III-nitride

high electron mobility transistors (HEMTs) in which

transport within the channel is quasi-ballistic in

nature. Following Landauer's transport theory and

charge calculation based on two-dimensional

electrostatics that incorporates negative momenta

states from the drain terminal, an analytic expression

for current as a function of terminal voltages is

developed. The model interprets the non-linearity of

access regions in non-self-aligned HEMTs. Effects of

Joule heating with temperature-dependent thermal

conductivity are incorporated in the model in a self-

consistent manner. With a total of 26 input

parameters, the analytic model offers reduced

empiricism compared to existing GaN HEMT models.

To verify the model, experimental I-V data of

InAlN/GaN with InGaN back-barrier HEMTs with

channel lengths of 42 and 105 nm are considered.

Additionally, the model is validated against numerical

I-V data obtained from DC hydrodynamic simulations

of an unintentionally doped AlGaN-on-GaN HEMT

with 50-nm gate length. The model is also verified

against pulsed I-V measurements of a 150-nm T-gate

GaN HEMT. Excellent agreement between the model

and experimental and numerical results for output

current, transconductance, and output conductance

is demonstrated over a broad range of bias and

temperature conditions.

Effects of surface plasma treatment on threshold

voltage hysteresis and instability in metal-insulator-

semiconductor (MIS) AlGaN/GaN heterostructure

HEMTs Department of Electronic and Electrical Engineering, The

University of Sheffield, Mappin Street, Sheffield S1 3JD,

United Kingdom

Centre for Materials and Structures, University of

Liverpool, The Quadrangle, Brownlow Hill, Liverpool L69

3GH, United Kingdom

Department of Material Science and Metallurgy, The

University of Cambridge, 27 Charles Babbage Road,

Cambridge CB3 0FS, United Kingdom

Centre for High-Frequency Engineering, University of

Cardiff, 5 The Parade, Newport Road, Cardiff CF24 3AA,

United Kingdom

Journal of Applied Physics

https://doi.org/10.1063/1.5027822

In a bid to understand the commonly observed

hysteresis in the threshold voltage (VTH) in

AlGaN/GaN metal-insulator-semiconductor high

electron mobility transistors during forward gate bias

stress, we have analyzed a series of measurements

on devices with no surface treatment and with two

different plasma treatments before the in-situ Al2O3

deposition. The observed changes between samples

were quasi-equilibrium VTH, forward bias related

VTH hysteresis, and electrical response to reverse

bias stress. To explain these effects, a disorder

induced gap state model, combined with a discrete

level donor, at the dielectric/semiconductor interface

was employed. Technology Computer-Aided Design

modeling demonstrated the possible differences in

the interface state distributions that could give a

consistent explanation for the observations.

Effects of channel thickness on structure and

transport properties of AlGaN/InGaN

heterostructures grown by pulsed metal organic

chemical vapor deposition State Key Discipline Laboratory of Wide Band Gap

Semiconductor Technology, School of Microelectronics,

Xidian University, No. 2 South TaiBai Road, Xi’an, 710071,

China

China Electronic Product Reliability and Environmental

Testing Research Institute, No. 110 Dongguanzhuang Road,

Guangzhou, 510610, China

School of Aerospace Science and Technology, Xidian

University, No. 2 South TaiBai Road, Xi’an, 710071, China

Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese

Academy of Sciences, China

Materials Research Bulletin

https://doi.org/10.1016/j.materresbull.2018.04.055

High-quality AlGaN/InGaN heterostructures are

grown and the effects of InGaN channel thickness on

the structure and transport properties are

GaNEX | III-N Technology Newsletter No. 65 | 23

investigated. With the increase of InGaN channel

thickness from 7 nm to 28 nm, the two-dimensional

electron gas density decreases continuously, while

the mobility shows a trend of increasing at first, and

then decreasing. The optimum thickness of 21 nm is

obtained for the In0.05Ga0.95N channel, achieving a

high electron mobility of 1712 cm2/V, which indicates

the huge potential for InGaN channel

heterostructures in high-frequency and high-power

applications. The variation in transport properties is

studied by analyzing the structure formation,

material quality, and interface characteristic in detail.

The results are not only beneficial for the further

study of the InGaN channel heterostructures, but also

instructive for the other inserted channel system.

A new approach to design wide band power

amplifiers by compensating parasitic elements of

transistors Electrical Engineering Department, PHD Student, Shiraz

University, Shiraz 7134851154, Iran

Electrical Engineering Department, Faculty of Engineering,

Shiraz University, Shiraz 7134851154, Iran

AEU - International Journal of Electronics and

Communications

https://doi.org/10.1016/j.aeue.2018.05.011

This paper presents an analytical approach to

compensate parasitic elements of transistors over a

wide frequency band. By absorbing parasitic

elements, an output matching network can be

realized by a conventional real to real impedance

transformer. This technique is a general procedure

which is adopted to design, simulate and implement

a wide band power amplifier (WPA) with commercial

packaged GaN transistors. Continuous wave signal

excitation in frequency band from 600 to 2800 MHz

demonstrates excellent power utilization factor with

output power higher than 40 dBm, drain efficiency

(DE) between 56.2% and 82.6% corresponding to

power added efficiency (PAE) of 52.6% to 81.6%

respectively. Simple analytical design strategy with

excellent performance suggests this method as a

promising way to design WPAs for modern

communication systems.

Polarization dependent charge control model for

microwave performance assessment of

AlGaN/GaN/AlGaN double heterostructure HEMTs SIC&T, GGSIPU, Dwarka, India

2.Department of Electronics, Acharya Narendra Dev

College, Kalkaji, India

3.Department of Electrical and Electronics Engineering,

Maharaja Agrasen Institute of Technology, Rohini, India

4.Department of Electronics and Communication

Engineering, Maharaja Agrasen Institute of Technology,

Rohini, India

Journal of Computational Electronics

https://doi.org/10.1007/s10825-018-1190-0

An accurate polarization dependent charge control-based analytical model is proposed for microwave performance assessment of [Math Processing Error] double heterostructure high electron mobility transistors (DH-HEMTs) in terms of current, transconductance, gate capacitances and cutoff frequency. An analytical expression correlating the sheet carrier concentration in the two 2DEGs formed at the upper and lower heterointerfaces of a DH-HEMT is obtained. AlGaN/GaN/AlGaN DH-HEMTs are found to exhibit superior RF performance as compared to its single heterostructure counterpart in terms of higher drain current, improved transconductance, higher gate capacitance and higher unity-gain cutoff frequency. This improvement in the DH-HEMT is mainly attributed to the formation of two 2DEGs (at top and the bottom heterointerface) as compared to the single 2DEG in a SH-HEMT. The variation of drain current with drain voltage and with gate voltage of AlGaN/GaN SH-HEMTs and AlGaN/GaN/AlGaN DH-HEMTs is obtained analytically and found to agree reasonably well with that obtained using ATLAS 2D device simulation, thereby validating the proposed model.

GaNEX | III-N Technology Newsletter No. 65 | 24

GROUP 5 – MEMS and Sensors Group leader: Marc Faucher (IEMN) Information selected by Knowmade

Impact of device parameters on performance of

one-port type SAW resonators on AlN/sapphire Research and Development Center for Solid State Lighting,

Institute of Semiconductors, Chinese Academy of Sciences,

Beijing 100083, People's Republic of China

University of Chinese Academy of Sciences, Beijing 100049,

People's Republic of China

NAURA Technology Group Co., Ltd, Beijing 100176,

People's Republic of China

Journal of Micromechanics and Microengineering

https://doi.org/10.1088/1361-6439/aabc87

We have studied the impact of various device

parameters including surface acoustic wavelength (λ),

interdigital transducers (IDT) finger apertures (LIDT),

number of reflector gratings (Nref), and reflector

types on the performance of one-port type AlN based

SAW resonators on sapphire systematically.

Experimental results indicate that the acoustic

velocity of 1 µm-AlN/sapphire bilayer structure is

5536 m s−1, 60% higher than that of LiNbO3 when λ

is 8 µm. For 1 µm-AlN/sapphire bilayer structure,

resonators with λ of 8 µm exhibit better performance

than that of resonators with λ of 12 µm and 16 µm,

with an electromechanical coupling coefficient () of

0.168%, and S11 magnitude difference at resonant

and anti-resonant frequency (ΔS11) of 0.42 dB. Both

ΔS11 and of resonators will increase sharply with the

increase of LIDT from 80 µm to 240 µm, exhibiting

140% and 150% improvement, respectively. The of

resonators will increase 38% with the increase of Nref

from 100 to 300. The impact of reflector types

including open-circuited and short-circuited

reflectors on performance of resonators is not

obvious.

AlN Ultrasound Sensor for Photoacoustic Lamb

Wave Detection in a High Temperature Environment Department of Mechanical and Aerospace Engineering,

North Carolina State University, Raleigh, NC 27695 USA

IEEE Transactions on Ultrasonics, Ferroelectrics, and

Frequency Control

https://doi.org/10.1109/TUFFC.2018.2839034

In this work, we present an ultrasound non-

destructive testing (NDT) method for high

temperature applications using laser-generated Lamb

waves and aluminum nitride (AlN) sensors. Lamb

waves were introduced to a stainless steel plate by

the Nd:YAG pulsed laser at one point and detected by

an AlN receiver at a distant position. The

fundamental symmetric (S0) and antisymmetric (A0)

Lamb waves generated by the pulsed laser were

successfully detected by the AlN sensor. This

detection was done on a stainless steel plate at

temperatures ranging from room temperature to

about 800 °C, with a signal-to-noise ratio (SNR) of

higher than 20 dB. Based on the time-of-flights (ToFs)

analysis, the ability of this NDT method to localize the

defect at a high temperature (~800 °C) has been

demonstrated.

AlN/ZnO/LiNbO3 packageless structure as a low-

profile sensor for potential on-body applications Institut Jean Lamour (IJL) UMR 7198, Université de

Lorraine-CNRS, Nancy, France

National Research University Moscow Power Engineering

Institute, 111250, Moscow, Russia

LPMR, Faculté des Sciences, Université Mohammed I,

Oujda, Morocco

LMOPS EA 4423 CentraleSupélec, Université de Lorraine,

Metz, France

Univ. Lille, CNRS, Centrale Lille, ISEN, Univ. Valenciennes,

UMR 8520-IEMN, LIA LICS/LEMAC, Lille, France

IEEE Transactions on Ultrasonics, Ferroelectrics, and

Frequency Control

https://doi.org/10.1109/TUFFC.2018.2839262

Surface acoustic wave (SAW) sensors find their

application in a growing number of fields. This

interest stems in particular from their passive nature

and the possibility of remote interrogation. Still, the

sensor package, due to its size, remains an obstacle

for some applications. In this regard, packageless

solutions are very promising. This paper describes the

potential of the AlN/ZnO/LiNbO3 structure for

packageless acoustic wave sensors. This structure,

based on the waveguided acoustic wave principle, is

GaNEX | III-N Technology Newsletter No. 65 | 25

studied numerically and experimentally. According to

the COMSOL simulations, a wave, whose particle

displacement is similar to a Rayleigh wave, is

confined within the structure when the AlN film is

thick enough. This result is confirmed by

comprehensive experimental tests, thus proving the

potential of this structure for packageless

applications, notably temperature sensing.

The impact of electrode materials on 1/f noise in

piezoelectric AlN contour mode resonators Department of Robotics Engineering, DGIST, Daegu 42988,

South Korea

Department of Electrical and Computer Engineering,

Carnegie Mellon University, Pittsburgh, PA 15213, USA

AIP Advances

https://doi.org/10.1063/1.5024961

This paper presents a detailed analysis on the impact

of electrode materials and dimensions on flicker

frequency (1/f) noise in piezoelectric aluminum

nitride (AlN) contour mode resonators (CMRs). Flicker

frequency noise is a fundamental noise mechanism

present in any vibrating mechanical structure, whose

sources are not generally well understood. 1 GHz AlN

CMRs with three different top electrode materials (Al,

Au, and Pt) along with various electrode lengths and

widths are fabricated to control the overall damping

acting on the device. Specifically, the use of different

electrode materials allows control of thermoelastic

damping (TED), which is the dominant damping

mechanism for high frequency AlN CMRs and largely

depends on the thermal properties (i.e. thermal

diffusivities and expansion coefficients) of the metal

electrode rather than the piezoelectric film. We have

measured Q and 1/f noise of 68 resonators and the

results show that 1/f noise decreases with increasing

Q, with a power law dependence that is about 1/Q4.

Interestingly, the noise level also depends on the

type of electrode materials. Devices with Pt top

electrode demonstrate the best noise performance.

Our results help unveiling some of the sources of 1/f

noise in these resonators, and indicate that a careful

selection of the electrode material and dimensions

could reduce 1/f noise not only in AlN-CMRs, but also

in various classes of resonators, and thus enable

ultra-low noise mechanical resonators for sensing

and radio frequency applications.

Theoretical study of the influence of surface effects

on GaN-based chemical sensors School of Electrical, Electronics and Computer Engineering,

University of Western Australia, Australia

School of Molecular Sciences, University of Western

Australia, Australia

Applied Surface Science

https://doi.org/10.1016/j.apsusc.2018.04.250

This paper presents the results of the theoretical

study of various factors affecting the charging

mechanism and characteristics of the

Ga2O3/GaN/AlGaN based ion sensitive field effect

transistor (ISFET). The relaxed atomic coordinates of

electrolytes and water molecules at the α-gallium

oxide (0 0 1) surface are used to calculate the

interfacial properties of gallium nitride based ion

selective field effect transistors. The hydration radius

of electrolytes along with the distance of the first and

the second layer of water on the surface are used to

derive the equilibrium reaction rates of the

protonation/deprotonation of surface sites and

adsorption/desorption of ions to the second layer.

The Triple Layer Model (TLM) is used to obtain the

redistribution of electrolytes when they are exposed

to the surface of the solid. Single site binding, TLM,

Poisson-Boltzmann and Schrodinger equations are

solved self-consistently to obtain the potential

distribution across the device and electrolyte,

accumulated charge at the surface and the density of

electrons in the channel. Sensitivity of the device is

affected by the thickness of the surface oxide on the

GaN-cap layer. These results indicate that the

inclusion of a thin layer of oxide at the surface of the

GaN-based chemical sensor accounts for the surface

chemistry, equilibrium reaction rates, and the relative

surface conduction-band offset with the redox levels

of electrolyte. The calculated values for the surface

acidity, oxide/GaN-cap barrier height and the

corresponding electron density in the channel as a

function of the thickness of the AlGaN barrier, the

GaN-cap and the surface oxide layer, distribution of

electric fields within the device, and the Nernstian-

slope of various structures, were compared with the

literature for validation and were in close proximity

of the experimental value. This model can be used to

further refine GaN- based sensors for a range of

applications.

GaNEX | III-N Technology Newsletter No. 65 | 26

Self-Assembled UV Photodetector Made by Direct

Epitaxial GaN Growth on Graphene Univ. Grenoble Alpes, 38000 Grenoble, France

CEA, LETI, MINATEC Campus, 38000 Grenoble, France

CNRS-Grenoble, Institut Néel, 38000 Grenoble, France

CEA, INAC-PHELIQS, 38000 Grenoble, France

CEA, LITEN, MINATEC Campus, 38000 Grenoble, France

ACS Appl. Mater. Interfaces

http://dx.doi.org/10.1021/acsami.8b01194

Hybrid systems based on the combination of

crystalline bulk semiconductors with 2D crystals are

identified as promising heterogeneous structures for

new optoelectronic applications. The direct

integration of III–V semiconductors on 2D materials is

very attractive to make practical devices but the

preservation of the intrinsic properties of the

underlying 2D materials remains a challenge. In this

work, we study the direct epitaxy of self-organized

GaN crystals on graphene. We demonstrate that

severe metal–organic chemical vapor deposition

growth conditions of GaN (chemically aggressive

precursors and high temperatures) are not

detrimental to the structural quality and the charge

carrier mobility of the graphene base plane.

Graphene can therefore be used both as an efficient

sensitive material and as a substrate for GaN epitaxy

to make a self-assembled UV photodetector. A

responsivity as high as 2 A W–1 is measured in the

UV-A range without any further postprocessing

compared to simple deposition of contact electrodes.

Our study opens the way to build new self-assembled

2D/III–V hybrid optoelectronic devices by direct

epitaxy.

GaNEX | III-N Technology Newsletter No. 65 | 27

GROUP 6 - Photovoltaics and Energy harvesting Group leader: Eva Monroy (INAC-CEA)

Information selected by Knowmade

Electric-field driven photoluminescence probe of

photoelectric conversion in InGaN-based

photovoltaics Beijing Key Laboratory for Magneto-Photoelectrical

Composite and Interface Science, School of Mathematics

and Physics, University of Science and Technology Beijing,

No. 30, Xueyuan Road, Beijing 100083, China

Optics Express

https://doi.org/10.1364/OE.26.00A615

The spatial distribution of electric field in

photovoltaic multiple quantum wells (MQWs) is

extremely important to dictate the mutual

competition of photoelectric conversion and optical

transition. Here, electric-field-driven

photoluminescence (PL) in both steady-state and

transient-state has been utilized to directly

investigate the internal photoelectric conversion

processes in InGaN-based MQW photovoltaic cell. As

applying the reversed external electric field, the

compensation of the quantum confined stark effect

(QCSE) in InGaN QW is beneficial to help the

photoabsorbed minor carriers drift out from the

localized states, whereas extremely weakening the PL

radiative recombination. A directly driven force by

the reversed external electric field decreases the

transit time of photocarriers drifting in InGaN QW.

And hence, the overall dynamic PL decay including

both the slow and fast processes gradually speeds up

from 19.2 ns at the open-circuit condition to 3.9 ns at

a negative bias of −3 V. In particular, the slow PL

decay lifetime declines more quickly than that of the

fast one. It is the delocalization of photocarriers by

electric-field drift that helps to further enhance the

high-efficiency photoelectric conversion except for

the tunneling transport in InGaN-based MQW

photovoltaics. Therefore, it can be concluded that the

electric-field PL probe may provide a direct method

for evaluating the photoelectric conversion in

multilayer quantum structures and related

multijunction photovoltaic cells.

New photoelectrical properties of InN: Interband

spectra and fast kinetics of positive and negative

photoconductivity of InN Institute for Physics of Microstructures RAS, 7,

Academicheskaya Str., Afonino, Nizhny Novgorod Region

603087, Russia

Lobachevsky State University of Nizhni Novgorod, 23

Gagarin Ave, Nizny Novgorod, 603950, Russia

Ioffe Institute, 26 Polytechnicheskaya, St. Petersburg

194021, Russia

St. Petersburg State Electro-technical University “LETI,”

197376, 5 Professora Popova Str., St. Petersburg, Russia

Journal of Applied Physics

https://doi.org/10.1063/1.5022844

Using a Fourier transform spectrometer and a pulsed

laser, we study spectra and kinetics of positive and

negative photoconductivity (PC) along with other

types of photoexcitation spectra of n-type InN

epilayers with Hall concentrations from 3 × 1017 to

5 × 1019 cm−3 at room and low temperatures. The

PC, absorption, and photoluminescence spectra of

the investigated InN samples correspond to a

degenerate homogenous direct band semiconductor.

In contrast to previous works, we observed positive

and negative PC with relaxation times in the nano-

and microsecond ranges. The sign of PC depends on

the temperature and the equilibrium carrier

concentration.

Optimization of polarization compensating

interlayers for InGaN/GaN MQW solar cells Department of Electronic Science, University of Delhi,

South Campus, New Delhi-10021, India

Department of Electronics, Deen Dayal Upadhyaya College,

University of Delhi, New Delhi-110078, India

Optoelectronics & MOEMS Group, CSIR-CEERI, Pilani,

Rajasthan-333031, India

AIP Conference Proceedings

https://doi.org/10.1063/1.5033012

Optimization of polarization compensating interlayer

(PCI) is performed numerically to improve the

photovoltaic properties of InGaN/GaN multiple

GaNEX | III-N Technology Newsletter No. 65 | 28

quantum well solar cell (MQWSC). Simulations are

performed to investigate the effect of change in

thickness and composition of PCI on the performance

of cell. Short circuit current density is increased as we

increase the thickness of the PCI. Changing the

constitution of PCI not only mitigates the negative

effects of polarization-induced electric fields but also

reduces the high potential barrier existing at the

QW/p-GaN hetero-interface. This claim is validated

by the performance shown by the cell containing

optimized PCI, as it shows an improved efficiency of

1.54 % under AM1.5G illumination.

Lithium and sodium adsorption properties of two-

dimensional aluminum nitride Indian Institute of Engineering Science and Technology

(IIEST), Shibpur, Howrah 711 103, India

Applied Surface Science

https://doi.org/10.1016/j.apsusc.2018.04.264

In this work the lithiation and sodiation properties of

2-dimensional (2D) AlN sheets are studied from

density functional theory (DFT) simulations. 2D AlN

showed theoretical specific capacity of 500.8 and

385.3 mA h g−1, maximum open circuit voltage of

1.49 and 1.86 V and diffusion barriers 0.40 and

0.15 eV, for Li and Na adsorption respectively. The

calculations show 2D AlN as a possible alternative as

anode material in Li-ion and Na-ion batteries. Further

the high specific capacity and small diffusion barriers

for Na atoms can make 2D AlN useful in

supercapacitors. The change in carrier transport

properties due to Li/Na adsorption on monolayer AlN

can also be useful in chemical/bio-sensors and

nanoelectronics devices.

Growth of gallium nitride nanowires on sapphire

and silicon by chemical vapor deposition for water

splitting applications Centre for Clean Energy and Nano Convergence, Hindustan

Institute of Technology and Science, Chennai, India

Crystal Growth Centre, Anna University, Chennai, India

Applied Surface Science

https://doi.org/10.1016/j.apsusc.2018.01.306

Gallium nitride (GaN) nanowires (NWs) are one of the

most promising candidates for photoelectrode

materials due to their tunable band edge potentials

and high stability in electrolytes. In this study, GaN

NWs were grown on sapphire (Al2O3) (002) and

silicon (Si) (111) substrate by chemical vapor

deposition (CVD) method. High quality of GaN NWs

on sapphire and silicon were confirmed by powder X-

ray diffraction (XRD). Structural characterization of

the synthesized NWs were performed using scanning

electron microscopy (SEM) and transmission electron

microscopy (TEM). The images revel the pristine and

smooth surface of GaN NWs. Further, optical

properties of GaN NWs were investigated at room

temperature photoluminescence emission. The

photocurrent density of GaN/Si NWs is found to be

higher than that of GaN/Al2O3 NWs. The GaN/Si NWs

having large surface area, are grown in a much

simpler method. GaN/Si NWs are potential candidate

for hydrogen energy generation, due to their

enhanced water splitting efficiency by utilizing solar

energy.

Structural properties of InGaN/GaN/Al2O3 structure

from reciprocal space mapping Department of Physics, Gazi University, Ankara, Turkey

Photonics Research Center, Gazi University, Ankara, Turkey

Nanotechnology Research Center, Bilkent University,

Ankara, Turkey

Journal of Materials Science: Materials in Electronics

https://doi.org/10.1007/s10854-018-9351-2

By using metal organic chemical vapor deposition technique, InGaN/GaN solar cell (SC) structure is deposited over sapphire (Al2O3) wafer as GaN buffer and GaN epitaxial layers. Structural properties of InGaN/GaN/Al2O3 SC structure is investigated by using high resolution X-ray diffraction technique dependent on In content. By using reciprocal space mapping, reciprocal space data are converted to w–θ data with a software. These w–θ data and full width at half maximum data are used for calculating lattice parameters. When compared with w–θ measurements in literature it is seen that especially a- lattice parameter is found very near to universal value from RSM. It is calculated as 3.2650 nm for sample A (S.A) GaN layer and 3.2570 nm for sample B (S.B) GaN layer on (105) asymmetric plane. Strain and stress calculations are made by using these lattice parameters. Strain and stress are calculated as 0.02363 and 8.6051 GPa for S.A GaN layer

GaNEX | III-N Technology Newsletter No. 65 | 29

respectively. Other results are given in tables in the results and discussion section of this article. Edge, screw and mixed type dislocations are calculated as mosaic defects. All these calculations are made for two samples on (002) symmetric and (105) asymmetric planes. As a result it is seen that measurements by using RSM give more sensitive results. a- lattice parameter calculated with this technique is the best indicator of this result.

GaNEX | III-N Technology Newsletter No. 65 | 30

GROUP 7 - Materials, Technology and Fundamental Group leader: Jean-Christophe Harmand (LPN-CNRS)

NANO

Information selected by Jesús Zúñiga Pérez (CRHEA-CNRS)

Carrier relaxation dynamics of InGaN/GaN dot-in-

nanowires Electrical Engineering, University of Michigan, USA

Electrical and Computer Engineering, McGill University,

Canada

Conference on Lasers and Electro-Optics

https://doi.org/10.1364/CLEO_AT.2018.JW2A.129

Carrier relaxation was investigated for InGaN/GaN

dot-in-nanowires using femtosecond pump-probe

in transmission 400nm pump/white light probe.

Though bright emitters, the localization of states

contributes to relaxation rates which are faster than

expected.

Optical design of GaN nanowire arrays for

photocatalytic applications Walter Schottky Institut and Physics Department,

Technische Universität München, Am Coulombwall 4,

85748 Garching, Germany

Journal of Applied Physics

https://doi.org/10.1063/1.5028476

GaN nanowire (NW) arrays are interesting

candidates for photocatalytic applications due to

their high surface-to-volume ratio and their

waveguide character. The integration of GaN NW

arrays on GaN-based light emitting diodes (LEDs),

serving as a platform for electrically driven NW-

based photocatalytic devices, enables an efficient

coupling of the light from the planar LED to the GaN

NWs. Here, we present a numerical study of the

influence of the NW geometries, i.e., the NW

diameter, length, and period, and the illumination

wavelength on the transmission of GaN NW arrays

on transparent substrates. A detailed numerical

analysis reveals that the transmission

characteristics for large periods are determined by

the waveguide character of the single NW, whereas

for dense GaN NW arrays inter-wire coupling and

diffraction effects originating from the periodic

arrangement of the GaN NWs dominate the

transmission. The numerically simulated results are

confirmed by experimental transmission

measurements. We also investigate the influence of

a dielectric NW shell and of the surrounding

medium on the transmission characteristics of a

GaN NW array.

Linearly polarized photoluminescence of InGaN

quantum disks embedded in GaN nanorods School of Natural Science, Ulsan National Institute of

Science and Technology (UNIST), Ulsan, 44919, Korea

Clarendon Laboratory, Department of Physics, University

of Oxford, Oxford, OX1 3PU, UK

Department of Physics, Soongsil University, Seoul, 06978,

Korea

Division of Physics and Semiconductor Science, Dongguk

University, Seoul, 04620, Korea

Department of Physics, Hong Kong University of Science

and Technology, Clear Water Bay, Hong Kong, China

Scientific Reports

https://doi.org/10.1038/s41598-018-26642-8

We have investigated the emission from

InGaN/GaN quantum disks grown on the tip of GaN

nanorods. The emission at 3.21 eV from the InGaN

quantum disk doesn’t show a Stark shift, and it is

linearly polarized when excited perpendicular to the

growth direction. The degree of linear polarization

is about 39.3% due to the anisotropy of the

nanostructures. In order to characterize a single

nanostructure, the quantum disks were dispersed

on a SiO2 substrate patterned with a metal

reference grid. By rotating the excitation

polarization angle from parallel to perpendicular

relative to the nanorods, the variation of overall PL

for the 3.21 eV peak was recorded and it clearly

showed the degree of linear polarization (DLP) of

51.5%.

GaNEX | III-N Technology Newsletter No. 65 | 31

Determination of strain relaxation in InGaN/GaN

nanowalls from quantum confinement and exciton

binding energy dependent photoluminescence

peak Applied Quantum Mechanics Laboratory, Indian Institute

of Technology Bombay, Powai, Mumbai, 400076, India

Scientific Reports

https://doi.org/10.1038/s41598-018-26725-6

GaN based nanostructures are being increasingly

used to improve the performance of various devices

including light emitting diodes and lasers. It is

important to determine the strain relaxation in

these structures for device design and better

prediction of device characteristics and

performance. We have determined the strain

relaxation in InGaN/GaN nanowalls from quantum

confinement and exciton binding energy dependent

photoluminescence peak. We have further

determined the strain relaxation as a function of

nanowall dimension. With a decrease in nanowall

dimension, the lateral quantum confinement and

exciton binding energy increase and the InGaN layer

becomes partially strain relaxed which decreases

the piezoelectric polarization field. The reduced

polarization field decreases quantum confined Stark

effect along the c-axis and increases electron-hole

wave-function overlap which further increases the

exciton binding energy. The strong dependency of

the exciton binding energy on strain is used to

determine the strain relaxation in these

nanostructures. An analytical model based on

fractional dimension for GaN/InGaN/GaN

heterostructures along with self-consistent

simulation of Schrodinger and Poisson equations

are used to theoretically correlate them. The larger

effective mass of GaN along with smaller

perturbation allows the fractional dimensional

model to accurately describe our system without

requiring first principle calculations.

Insight into the performance of multi-color

InGaN/GaN nanorod light emitting diodes Institute of Materials and Systems for Sustainability

(IMaSS), Nagoya University, Nagoya, Japan

Center for Integrated Research of Future Electronics

(CIRFE), Nagoya University, Nagoya, Japan

Korea Institute of Ceramic Engineering and Technology,

Jinju, South Korea

Ioffe Institute, 194021, St. Petersburg, Russia

Department of Electrical Engineering and Computer

Science, Nagoya University, Nagoya, Japan

Scientific Reports

https://doi.org/10.1038/s41598-018-25473-x

We report on the thorough investigation of light

emitting diodes (LEDs) made of core-shell nanorods

(NRs) with InGaN/GaN quantum wells (QWs) in the

outer shell, which are grown on patterned

substrates by metal-organic vapor phase epitaxy.

The multi-bands emission of the LEDs covers nearly

the whole visible region, including UV, blue, green,

and orange ranges. The intensity of each emission is

strongly dependent on the current density,

however the LEDs demonstrate a rather low color

saturation. Based on transmission electron

microscopy data and comparing them with

electroluminescence and photoluminescence

spectra measured at different excitation powers

and temperatures, we could identify the spatial

origination of each of the emission bands. We show

that their wavelengths and intensities are governed

by different thicknesses of the QWs grown on

different crystal facets of the NRs as well as

corresponding polarization-induced electric fields.

Also the InGaN incorporation strongly varies along

the NRs, increasing at their tips and corners, which

provides the red shift of emission. With increasing

the current, the different QW regions are activated

successively from the NR tips to the side-walls,

resulting in different LED colors. Our findings can be

used as a guideline to design effectively emitting

multi-color NR-LEDs.

Long-range ordered vertical III-nitride nano-

cylinder arrays via plasma-assisted atomic layer

deposition Ali Haider et al.

J. Mater. Chem. C

http://dx.doi.org/10.1039/C8TC01165F

In this work, we demonstrate vertical GaN, AlN, and

InN hollow nano-cylindrical arrays (HNCs) grown on

Si substrates using anodized aluminum oxide (AAO)

GaNEX | III-N Technology Newsletter No. 65 | 32

membrane templated low-temperature plasma-

assisted atomic layer deposition (PA-ALD). III-nitride

HNCs have been characterized for their structural,

chemical, surface, and optical properties. The

material properties of nanostructured III-nitride

materials have been compared with the thin-film

counterparts which were also grown using PA-ALD.

Our results revealed that long-range ordered arrays

of III nitride HNCs were successfully integrated on Si

substrates and possess hexagonal polycrystalline

wurtzite crystalline structure. Such long-range

ordered wafer-scale III-nitride nanostructures might

be potentially used in piezotronic sensing, energy

harvesting, resistive memory, III-nitride

photovoltaics, and (photo)catalysis.

Quantified Hole Concentration in AlGaN

Nanowires for High-Performance Ultraviolet

Emitters Chao Zhao et al.

Nanoscale

http://dx.doi.org/10.1039/C8NR02615G

P-type doping in wide bandgap and new classes of

ultra-wide bandgap materials has long been a

scientific and engineering problem. The challenges

arise from the large activation energy of dopants

and high densities of dislocations in materials. We

report here, a significantly enhanced p-type

conduction using high-quality AlGaN nanowires. For

the first time, the hole concentration in Mg-doped

AlGaN nanowires is quantified. The incorporation of

Mg into AlGaN was verified by correlation with

photoluminescence and Raman measurements. The

open-circuit potential measurements further

confirmed the p-type conductivity; while Mott-

Schottky experiments measured a hole

concentration of 1.3×1019 cm-3. These results from

photoelectrochemical measurements allow us to

design prototype ultraviolet (UV) light-emitting

diodes (LEDs) incorporating the AlGaN quantum-

disks-in-nanowire and optimized p-type AlGaN

contact layer for UV-transparency. The ~335-nm

LEDs exhibited a low turn-on voltage of 5 V with a

series resistance of 32 Ω, due to the efficient p-type

doping of the AlGaN nanowires. The bias-

dependent Raman measurements further revealed

the negligible self-heating of devices. This study

provides an attractive solution to evaluate electrical

properties of AlGaN, which is applicable to other

wide bandgap nanostructures. Our results are

expected to open doors to new applications for

wide and ultra-wide bandgap materials.

Monitoring the formation of GaN nanowires in

molecular beam epitaxy by polarization-resolved

optical reflectometry Paul-Drude-Institut für Festkörperelektronik, Leibniz-

Institut im Forschungsverbund Berlin e.V,

Hausvogteiplatz 5-7, 10117 Berlin, Germany

Grupo de Electrónica y Semiconductores, Dpto. Física

Aplicada, Universidad Autónoma de Madrid, C/ Francisco

Tomás y Valiente 7, 28049 Madrid, Spain

CrystEngComm

http://dx.doi.org/10.1039/C8CE00431E

We analyze the temporal variation of the substrate

optical reflectance during the formation of GaN

nanowires in molecular beam epitaxy using

transverse electric and transverse magnetic

polarized light. The time dependence of the

reflectance signal is simulated using an effective

medium approach that takes into account the

spatial fluctuations in the length and density of the

nanowire ensemble within the area probed by the

laser beam. Our study demonstrates that optical

reflectometry is a powerful technique to detect the

onset of nanowire nucleation, assess the deposition

rate, and estimate the fluctuations in the nanowire

length and covered area fraction at the μm scale.

NON/SEMI POLAR

Information selected by Philippe De Mierry (CRHEA-CNRS)

Direct Pulse Position Modulation of a 410 nm

Semipolar GaN Laser Diode for Space Optical

Communications Electrical and Computer Engineering Department,

University of California, Santa Barbara, USA

Materials Department, University of California, Santa

Barbara, USA

Conference on Lasers and Electro-Optics

https://doi.org/10.1364/CLEO_SI.2018.STu4Q.3

GaNEX | III-N Technology Newsletter No. 65 | 33

A semipolar GaN laser was characterized for space

optical communications, achieving a peak power of

160 mW. Periodic and random M-ary pulse position

modulation sequences with pulse widths of 5 ns

and 10 ns were demonstrated.

Zinc oxide clad limited area epitaxy semipolar III-

nitride laser diodes Department of Electrical and Computer Engineering,

University of California, Santa Barbara, CA 93106, USA

Materials Department, University of California, Santa

Barbara, CA 93106, USA

Department of Electrical and Computer Engineering,

University of Wisconsin-Madison, Madison, WI 53706,

USA

Optics Express

https://doi.org/10.1364/OE.26.012490

We report continuous-wave (CW) blue semipolar

(202̲1) III-nitride laser diodes (LDs) that incorporate

limited area epitaxy (LAE) n-AlGaN bottom cladding

with thin p-GaN and ZnO top cladding layers. LAE

mitigates LD design limitations that arise from

stress relaxation, while ZnO layers reduce epitaxial

growth time and temperature. Numerical modeling

indicates that ZnO reduces the internal loss and

increases the differential efficiency of TCO clad LDs.

Room temperature CW lasing was achieved at 445

nm for a ridge waveguide LD with a threshold

current density of 10.4 kA/cm2, a threshold voltage

of 5.8 V, and a differential resistance of 1.1 Ω.

AlxGa1− xN-based semipolar deep ultraviolet light-

emitting diodes Yanmar Co., Ltd., Japan

Division of Materials and Manufacturing Science, Osaka

University, Suita, Osaka 565-0871, Japan

Applied Physics Express

https://doi.org/10.7567/APEX.11.061001

Deep ultraviolet (UV) emission from Al x Ga1− x N-

based light-emitting diodes (LEDs) fabricated on

semipolar ($1\bar{1}02$) (r-plane) AlN substrates is

presented. The growth conditions are optimized. A

high NH3 flow rate during metalorganic vapor

phase epitaxy yields atomically flat Al y Ga1− y N (y

> x) on which Al x Ga1− x N/Al y Ga1− y N multiple

quantum wells with abrupt interfaces and good

periodicity are fabricated. The fabricated r-Al x

Ga1− x N-based LED emits at 270 nm, which is in

the germicidal wavelength range. Additionally, the

emission line width is narrow, and the peak

wavelength is stable against the injection current,

so the semipolar LED shows promise as a UV

emitter.

Trade-off between bandwidth and efficiency in

semipolar (202⎯⎯1⎯⎯) InGaN/GaN single- and

multiple-quantum-well light-emitting diodes Center for High Technology Materials, University of New

Mexico, Albuquerque, New Mexico 87106, USA

Electrical and Computer Engineering Department,

University of California, Santa Barbara, California 93106,

USA

Materials Department, University of California, Santa

Barbara, California 93106, USA

Appl. Phys. Lett.

https://doi.org/10.1063/1.5032115

InGaN/GaN light-emitting diodes (LEDs) with large

modulation bandwidths are desirable for visible-

light communication. Along with modulation speed,

the consideration of the internal quantum

efficiency (IQE) under operating conditions is also

important. Here, we report the modulation

characteristics of semipolar (202⎯⎯1⎯⎯) InGaN/GaN

(LEDs) with single-quantum well (SQW) and

multiple-quantum-well (MQW) active regions

grown on free-standing semipolar GaN substrates

with peak internal quantum efficiencies (IQEs) of

0.93 and 0.73, respectively. The MQW LEDs exhibit

on average about 40–80% higher modulation

bandwidth, reaching 1.5 GHz at 13 kA/cm2, but

about 27% lower peak IQE than the SQW LEDs. We

extract the differential carrier lifetimes (DLTs), RC

parasitics, and carrier escape lifetimes and discuss

their role in the bandwidth and IQE characteristics.

A coulomb-enhanced capture process is shown to

rapidly reduce the DLT of the MQW LED at high

current densities. Auger recombination is also

shown to play little role in increasing the speed of

the LEDs. Finally, we investigate the trade-offs

between the bandwidth and efficiency and

introduce the bandwidth-IQE product as a potential

figure of merit for optimizing speed and efficiency

in InGaN/GaN LEDs.

GaNEX | III-N Technology Newsletter No. 65 | 34

Study of dual nitridation processes in growth of

non-polar a-plane AlGaN epi-layers Advanced Photonics Center, Southeast University,

Nanjing 210096, Jiangsu, China

College of Physics and Electronic Engineering, Changshu

Institute of Technology, Changshu 215500, Jiangsu, China

Materials Letters

https://doi.org/10.1016/j.matlet.2018.05.055

The effect of dual nitridation processes for both r-

plane sapphire and low temperature-grown AlN (LT-

AlN) nucleation layer on non-polar a-plane AlGaN

epi-layer was studied intensively. A root-mean-

square value as small as 1.54 nm for a-plane

Al0.53Ga0.47N epi-layer was achieved. It was

revealed that the generation of AlN grains as well as

the coalescence and recrystallization of LT-AlN

islands were the key factors for growing a-plane

AlGaN epi-layers with smooth surface morphology.

Meanwhile, the evolution of surface morphology

with varied nitridation processes and the

mechanisms for improving surface morphology of a-

plane AlGaN epi-layers were also investigated.

Electronic states of deep trap levels in a-plane GaN

templates grown on r-plane sapphire by HVPE Korea Basic Science Institute, 169-148, Gwahak-ro,

Yuseong-gu, Daejeon, Republic of Korea

Quantum-Function Research Laboratory, Hanyang

University, Department of Physics, Seoul, 133-791,

Republic of Korea

Department of Science Education, Jeonju University, 303

Cheonjam-ro, Wansan-gu, Jeollabuk-do, Republic of

Korea

Analytical Laboratory of Advanced Ferroelectric Crystals,

Jeonju University, 303 Cheonjam-ro, Wansan-gu,

Jeollabuk-do, Republic of Korea

Scientific Reports

https://doi.org/10.1038/s41598-018-26290-y

We report on the defect states incorporated in a-plane GaN crystals grown on r-plane sapphire substrates by hydride vapor phase epitaxy (HVPE), using deep level transient spectroscopy (DLTS). Two defect states were observed at 0.2 eV and 0.55 eV below the conduction band minimum with defect densities of 5 × 1012/cm3 and 4.7 × 1013/cm3, respectively. The size of capture cross section, non-linear relation of trap densities from the depth

profile, filling pulse width, and PL measurements indicated that the electronic deep trap levels in a-plane GaN on r-plane sapphire by HVPE originated from non-interacting point defects such as NGa, complex defects involving Si, O, or C, and VGa-related centres. Even though the a-plane GaN templates were grown by HVPE with high growth rates, the electronic deep trap characteristics are comparable to those of a-plane GaN layers of high crystal quality grown by MOCVD. This study prove that the growth of a-plane GaN templates on r-plane sapphire by HVPE is a promising method to obtain a-plane GaN layers efficiently and economically without the degradation of electrical characteristics.

MATERIAL / CHARACTERIZATION / EQUIPMENT / NUMERICAL SIMULATION

Information selected by Agnès Trassoudaine (Université d'Auvergne)

and Yvon Cordier (CRHEA-CNRS)

Macrodefect-free, large, and thick GaN bulk

crystals for high-quality 2–6 in. GaN substrates by

hydride vapor phase epitaxy with hardness control SCIOCS Co., Ltd., Hitachi, Ibaraki 319-1418, Japan

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.065502

On the basis of a novel crystal hardness control, we

successfully realized macrodefect-free, large (2–6

in.) and thick +c-oriented GaN bulk crystals by

hydride vapor phase epitaxy. Without the hardness

control, the introduction of macrodefects including

inversion domains and/or basal-plane dislocations

seemed to be indispensable to avoid crystal

fracture in GaN growth with millimeter thickness.

However, the presence of these macrodefects

tended to limit the applicability of the GaN

substrate to practical devices. The present

technology markedly increased the GaN crystal

hardness from below 20 to 22 GPa, thus increasing

the available growth thickness from below 1 mm to

over 6 mm even without macrodefect introduction.

The 2 and 4 in. GaN wafers fabricated from these

crystals had extremely low dislocation densities in

the low- to mid-105 cm−2 range and low off-angle

variations (2 in.: <0.1°; 4 in.: ~0.2°). The realization

of such high-quality 6 in. wafers is also expected.

GaNEX | III-N Technology Newsletter No. 65 | 35

Epitaxial growth of single-crystalline AlN layer on

Si(111) by DC magnetron sputtering at room

temperature Department of Materials Science and Engineering, Seoul

National University, Seoul 08826, Korea

Korea Advanced Nano Fab Center, Suwon 16229, Korea

Energy Semiconductor Research Center, Advanced

Institutes of Convergence Technology, Seoul National

University, Suwon 16229, Korea

Research Institute of Advanced Materials & Inter-

university Semiconductor Research Center, Seoul

National University, Seoul 08826, Korea

Japanese Journal of Applied Physics

https://doi.org/10.7567/JJAP.57.060306

The epitaxial growth of an AlN layer on a Si(111)

substrate at room temperature by DC magnetron

sputtering was investigated. The predeposition of a

5-nm-thick Al layer on the Si substrate before the

AlN deposition was found to be crucial for the

epitaxial growth of the AlN layer. The orientation

relationships of AlN/Al/Si were observed to be

AlN[1-100] ∥ Al[0-11] ∥ Si[11-2] and AlN[11-20] ∥

Al[011] ∥ Si[1-10], indicating the epitaxial growth of

the AlN layer on the Si(111) substrate. This epitaxial

growth of the AlN layer was attributed to the

smaller lattice mismatches between AlN[1-100] and

Al[0-11] and AlN[11-20] and Al[011] than that

between AlN[11-20] and Si[1-10].

Reduction of Dislocations in GaN on Silicon

Substrate Using In Situ Etching SUMCO Corporation, 1-52 Kubara, Yamashiro-cho, Imari

849-4256, Japan

Department of Electrical Engineering and Computer

Science, Nagoya University

Institute of Materials and Systems for Sustainability,

Nagoya University

Venture Business Laboratory, Nagoya University

Akasaki Research Center, Nagoya University

Phys. Status Solidi B

https://doi.org/10.1002/pssb.201700387

A gallium nitride (GaN) epitaxial layer with a low

density of threading dislocations is successfully

grown on a silicon substrate by using in situ gas

etching. Silicon nitride (SiNx) film is used as a mask,

and ammonia is intermittently supplied in hydrogen

ambient during the etching. After etching,

high‐density deep pits appeared on the surface of a

GaN template layer and corresponded to the

threading dislocations in the layer. In this novel

method, before growing an additional GaN layer on

the template GaN layer, a second SiNx layer is

deposited after the etching process, and this layer

prevents GaN nuclei from growing on the upper

side‐walls of the pits. By using this method, the

density of threading dislocations of the GaN surface

is reduced to 6.7 × 107 cm−2. This method is cost

effective, completing all the necessary processes in

one growth run without taking samples out from a

metalorganic chemical vapor deposition (MOCVD)

reactor.

Detection of edge component of threading

dislocations in GaN by Raman spectroscopy Department of Materials Science and Engineering,

Nagoya University, Nagoya 464-8603, Japan

GaN Advanced Device Open Innovation Laboratory (GaN-

OIL), National Institute of Industrial Science and

Technology (AIST), Nagoya 464-8601, Japan

Institute of Materials and Systems for Sustainability

(IMaSS), Nagoya University, Nagoya 464-8603, Japan

Denso Corporation Advanced Research and Innovation

Center, Nisshin, Aichi 470-0111, Japan

Applied Physics Express

https://doi.org/10.7567/APEX.11.061002

We succeeded in measuring the density and

direction of the edge component of threading

dislocations (TDs) in c-plane (0001) GaN by micro-

Raman spectroscopy mapping. In the micro-Raman

spectroscopy mapping of the E2 H peak shift

between 567.85 and 567.75 cm−1, six different

contrast images are observed toward directions of

$\langle 1\bar{1}00\rangle $. By comparing X-ray

topography and etch pit images, the E2 H peak shift

is observed where the edge component of TDs

exists. In contrast, the E2 H peak is not observed

where the screw component of TDs exists.

GaNEX | III-N Technology Newsletter No. 65 | 36

Observation and discussion of avalanche

electroluminescence in GaN p-n diodes offering a

breakdown electric field of 3 MV cm−1 Electrical and Computer Engineering Department,

University of California at Davis, Davis, CA 95616 United

States of America

Solid State Lighting & Energy Electronics Center,

University of California at Santa Barbara, Santa Barbara,

CA 93106 United States of America

Semiconductor Science and Technology

https://doi.org/10.1088/1361-6641/aab73d

We report on the first observation of avalanche

electroluminescence resulting from band-to-band

recombination (BTBR) of electron hole pairs at the

breakdown limit of Gallium Nitride p-n diodes

grown homo-epitaxially on single crystalline GaN

substrates. The diodes demonstrated a near ideal

breakdown electric field of 3 MV cm−1 with

electroluminescence (EL) demonstrating sharp

peaks of emission energies near and at the band

gap of GaN. The high critical electric field, near the

material limit of GaN, was achieved by generating a

smooth curved mesa edge with low plasma

damage, using etch engineering without any use of

field termination. The superior material quality was

critical for such a near-ideal performance. An

electric field of 3 MV cm−1 recorded at the

breakdown resulted in impact ionization, confirmed

by a positive temperature dependence of the

breakdown voltage. The spectral data provided

evidence of BTBR of electron hole pairs that were

generated by avalanche carrier multiplication in the

depletion region.

Linearly polarized photoluminescence of

anisotropically strained c-plane GaN layers on

stripe-shaped cavity-engineered sapphire

substrate Department of Materials Science and Engineering, Seoul

National University, Seoul 08826, South Korea

Energy Semiconductor Research Center, Advanced

Institutes of Convergence Technology, Suwon 16229,

South Korea

Research Institute of Advanced Materials & Inter-

University Semiconductor Research Center, Seoul

National University, Seoul 08826, South Korea

Appl. Phys. Lett.

https://doi.org/10.1063/1.5025221

Anisotropic in-plane strain and resultant linearly

polarized photoluminescence (PL) of c-plane GaN

layers were realized by using a stripe-shaped cavity-

engineered sapphire substrate (SCES). High

resolution X-ray reciprocal space mapping

measurements revealed that the GaN layers on the

SCES were under significant anisotropic in-plane

strain of −0.0140% and −0.1351% along the

directions perpendicular and parallel to the stripe

pattern, respectively. The anisotropic in-plane strain

in the GaN layers was attributed to the anisotropic

strain relaxation due to the anisotropic

arrangement of cavity-incorporated membranes.

Linearly polarized PL behavior such as the observed

angle-dependent shift in PL peak position and

intensity comparable with the calculated value

based on k·p perturbation theory. It was found that

the polarized PL behavior was attributed to the

modification of valence band structures induced by

anisotropic in-plane strain in the GaN layers on the

SCES.

The influence of point defects on the thermal

conductivity of AlN crystals Department of Materials Science and Engineering, North

Carolina State University, Raleigh, North Carolina 27695,

USA

Leibniz Institute for Crystal Growth (IKZ), Max-Born-Str.

2, 12489 Berlin, Germany

Tsukuba Research Laboratories, Tokuyama Corporation,

Tsukuba, Ibaraki 300-4247, Japan

Adroit Materials, Inc., 2054 Kildaire Farm Rd., Cary, North

Carolina 27518, USA

Department of Applied Chemistry, Tokyo University of

Agriculture and Technology, Koganei, Tokyo 184-8588,

Japan

Journal of Applied Physics

https://doi.org/10.1063/1.5028141

The average bulk thermal conductivity of free-

standing physical vapor transport and hydride vapor

phase epitaxy single crystal AlN samples with

different impurity concentrations is analyzed using

the 3ω method in the temperature range of 30–

325 K. AlN wafers grown by physical vapor transport

show significant variation in thermal conductivity at

GaNEX | III-N Technology Newsletter No. 65 | 37

room temperature with values ranging between

268 W/m K and 339 W/m K. AlN crystals grown by

hydride vapor phase epitaxy yield values between

298 W/m K and 341 W/m K at room temperature,

suggesting that the same fundamental mechanisms

limit the thermal conductivity of AlN grown by both

techniques. All samples in this work show phonon

resonance behavior resulting from incorporated

point defects. Samples shown by optical analysis to

contain carbon-silicon complexes exhibit higher

thermal conductivity above 100 K. Phonon

scattering by point defects is determined to be the

main limiting factor for thermal conductivity of AlN

within the investigated temperature range.

Mesa orientation dependence of lateral growth of

GaN microchannel epitaxy by electric liquid-phase

epitaxy using a mesa-shaped substrate Department of Materials Science and Engineering, Meijo

University, Nagoya 468-8502, Japan

Department of Applied Chemistry, Meijo University,

Nagoya 468-8502, Japan

Journal of Crystal Growth

https://doi.org/10.1016/j.jcrysgro.2018.04.011

Growth of (0 0 0 1) GaN microchannel epitaxy by

electric liquid phase epitaxy using a mesa-shaped

substrate was optimized to enhance lateral growth

by systematically changing the mesa direction. It

was found that the formation of the (−1 2 −1 2) and

(1 −2 1 2) facets on the sides strongly suppressed

lateral growth. The area of the facets increased as

the offset angle of the mesa direction from the

[1 1 −2 0] axis increased. At an offset angle of 30°,

lateral growth was fully suppressed by the

formation of the (−1 2 −1 2) and (1 −2 1 2) facets on

the whole sides. The (−1 2 −1 2) and (1 −2 1 2)

planes are thought to be stable in electric liquid-

phase epitaxy under our extremely Ga-rich

experimental conditions. These facets formed

readily on the sides when the growth front directed

to [1 −2 1 0]. On the other hand, the [1 1 −2 0] mesa

orientation resulted in wide lateral growth. This is

because the (1 −1 0 0) facets are less stable than

the (0 0 0 1) and (0 0 0 −1) planes, and do not

hinder lateral growth.

Effect of the Sapphire-Nitridation Level and

Nucleation-Layer Enrichment with Aluminum on

the Structural Properties of AlN Layers Rzhanov Institute of Semiconductor Physics, Russian

Academy of Sciences, Siberian Branch, Novosibirsk,

Russia

Ioffe Institute, St. Petersburg, Russia

Novosibirsk State University, Novosibirsk, Russia

Semiconductors

https://doi.org/10.1134/S1063782618060143

The effect of atomic aluminum deposited onto

sapphire substrates with different nitridation levels

on the quality of AlN layers grown by ammonia

molecular-beam epitaxy is investigated. The

nitridation of sapphire with the formation of ~1

monolayer of AlN is shown to ensure the growth of

layers with a smoother surface and better crystal

quality than in the case of the formation of a

nitrided AlN layer with a thickness of ~2

monolayers. It is demonstrated that the change in

the duration of exposure of nitrided substrates to

the atomic aluminum flux does not significantly

affect the parameters of subsequent AlN layers.

In situ transmission electron microscopy of

transistor operation and failure Department of Mechanical and Nuclear Engineering, The

Pennsylvania State University, University Park, PA 16802,

United States of America

Air Force Research Laboratory, 2941 Hobson Way,

Wright-Patterson AFB OH 45433, United States of

America

Materials Research Laboratory, Massachusetts Institute

of Technology, Cambridge, MA 02139, United States of

America

Nanotechnology

https://doi.org/10.1088/1361-6528/aac591

Microscopy is typically used as a post-mortem

analytical tool in performance and reliability studies

on nanoscale materials and devices. In this study,

we demonstrate real time microscopy of the

operation and failure of AlGaN/GaN high electron

mobility transistors inside the transmission electron

microscope. Loading until failure was performed on

the electron transparent transistors to visualize the

failure mechanisms caused by self-heating. At lower

GaNEX | III-N Technology Newsletter No. 65 | 38

drain voltages, thermo-mechanical stresses induce

irreversible microstructural deformation, mostly

along the AlGaN/GaN interface, to initiate the

damage process. At higher biasing, the self-heating

deteriorates the gate and catastrophic failure takes

place through metal/semiconductor inter-diffusion

and/or buffer layer breakdown. This study indicates

that the current trend of recreating the events,

from damage nucleation to catastrophic failure, can

be replaced by in situ microscopy for a quick and

accurate account of the failure mechanisms.

Polarity and threading dislocation dependence of

surface morphology of c-GaN films exposed to HCl

vapor Department of Physics and Research Institute for Basic

Sciences, Kyung Hee University,

26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447,

Korea

J. Mater. Chem. C

http://dx.doi.org/10.1039/C8TC01640B

Polarity and threading dislocation dependence of

surface morphology of c-GaN films exposed to HCl

vapor at temperatures of 750 and 810oC was

investigated. For N-polar GaN, some regions were

severely etched in such a way that vertically-aligned

nanopipes were formed while areas other than

those occupied by nanopipes were barely etched.

Cross-sectional transmission electron microscopy

analysis revealed that the bottom of nanopipes was

observed to be connected to threading

dislocation(s) while no threading-dislocation was

observed beneath the unetched surface of N-polar

GaN. In comparison, threading-dislocation-free

region in Ga-polar GaN domains were heavily

etched, and GaN nanoneedles were formed on a

relatively flat surface at temperature as low as

750oC. In order to understand the etched surface

morphology of Ga-polar GaN (nanoneedles on a

relatively flat surface), we proposed a physical

model to describe this etching behavior, and a

computational simulation based on our proposed

model could explain the etched surface morphology

of a Ga-polar GaN film exposed to HCl vapor.

GaNEX | III-N Technology Newsletter No. 65 | 39

PRESS RELEASE Technical and economic information selected by Knowmade

ELECTRONICS

Exagan launches G-FET power transistors and G-DRIVE intelligent fast-switching products for consumer, industrial and automotive applications Source : SemiconductorToday

At PCIM Europe 2018 (Power Conversion and Intelligent Motion) in Nuremberg, Germany (5-7 June), gallium

nitride technology start-up Exagan of Grenoble and Toulouse, France (founded in 2014 with support from CEA-

Leti and Soitec) is launching its G-FET power transistors and G-DRIVE intelligent fast-switching solution, featuring

an integrated driver and transistor in a single package. The firm claims that the GaN-based devices are easy to

design into electronic products, paving the way for fast chargers that comply with the USB power delivery (PD)

3.0 type C standard while providing exceptional power performance and integration.

At PCIM Europe, Exagan is showcasing the use of its high-power-density GaN-on-silicon devices to create ultra-

fast, efficient and small 45-65W chargers, including demonstrating its electrical-converter expertise and how

both the G-FET and G-DRIVE can benefit new converter product designs and their applications.

“The market potential for our products is enormous including all portable electronic devices as well as homes,

restaurants, hotels, airports, automobiles and more,” reckons president & CEO Frédéric Dupont. “In the near

future, users will be able to quickly charge their smart phones, tablets, laptops and other devices simply by

plugging a standard USB cable into a small, generic mobile charger.”

The ability of USB type C ports to serve as universal connections for the simultaneous transfer of electrical

power, data and video is leading to tremendous growth. The number of devices with at least one USB type C

port will multiply from 300 million units in 2016 to nearly 5 billion by 2021, forecasts market research firm IHS

Markit.

Aiming to accelerate the power electronics industry’s adoption of cost-effective GaN-based solutions for the

charger market, Exagan uses 200mm GaN-on-Si wafers, achieving highly cost-efficient high-volume

manufacturing. The firm is now sampling its fast, energy-efficient devices to key customers while ramping up

production to begin volume shipments of G-FET and G-DRIVE products.

Read more

Transphorm’s HV GaN FETs used in Seasonic’s new high-efficiency 1.6kW PFC platform Source : SemiconductorToday

Transphorm Inc of Goleta, near Santa Barbara, CA, USA — which designs and manufactures JEDEC- and AEC-

Q101-qualified gallium nitride (GaN) semiconductors — says that its high-voltage (HV) GaN field-effect

transistors (FETs) are being used by Seasonic Electronics Co of Taipei, Taiwan in its new 1600W bridgeless

totem-pole power factor correction (PFC) platform. The 1600T is the power supply manufacturer’s highest

GaNEX | III-N Technology Newsletter No. 65 | 40

performing PFC platform to date, at greater than 99% efficiency. Notably, the introduction of GaN delivers a 2%

efficiency increase and 20% power density increase over Seasonic’s previous silicon-based platform.

The 1600T platform will be scaled and deployed in catalog products targeting the charger (e-scooters, industrial,

etc), gaming, server and PC power markets.

“When researching semiconductor technologies that would enable us to reach world-leading efficiency levels,

gallium nitride stood out as an attractive alternative to silicon,” says Seasonic’s director of R&D Paul Lin. “We

knew the bridgeless totem-pole PFC was the topology we would use in our first high-voltage GaN power

platform. So, we needed power semiconductors capable of successfully capitalizing on that topology,” he adds.

“We wanted a GaN solution that could be backed by our standard warranty. We ultimately opted for

Transphorm’s FETs within the 1600T given their proven performance and reliability that allowed us to meet

those requirements.”

The 1600T platform employs Transphorm’s TP65H035WS device, a 650V GaN FET with an on-resistance

(RDS(on)) of 35mΩ in a standard TO-247 package. The transistor achieves increased efficiency in hard-and soft-

switched circuits, providing power systems engineers options when designing products. Further, the

TP65H035WS pairs with commonly used gate drivers to simplify designs while controlling costs. Also,

Transphorm claims that its GaN typically delivers greater headroom and noise immunity compared with other

available GaN FETs. The TP65H035WS’ typical gate threshold is 4V with a maximum gate voltage of ±20V.

Given GaN’s relative newness in high-voltage applications, Transphorm offers in-depth field application support

and hands-on training. Seasonic leveraged the firm’s experts to strengthen the design itself while speeding time

to market. For example, Transphorm’s guidance helped Seasonic’s team ramp on use of a simple, low-cost

digital signal processor (DSP) to control the totem-pole PFC. Transphorm also aided in the platform’s component

selection and system layout, ensuring optimal GaN performance. Ultimately, the co-development directly

impacted Seasonic’s ability to drive up thermal efficiency while increasing power output, says Transphorm.

Read more

Transphorm’s new Gen III GaN power conversion platform increases noise immunity and reduces switching noise Source : SemiconductorToday

Transphorm Inc of Goleta, near Santa Barbara, CA, USA — which designs and manufactures JEDEC- and AEC-

Q101-qualified high-voltage (HV) gallium nitride (GaN) field-effect transistors (FETs) for high-voltage power

conversion applications — has announced availability of its third-generation (Gen III) 650V GaN FETs. Power

transistors built on Gen III technology yield lower electromagnetic interference (EMI), increased gate noise

immunity, and greater headroom in circuit applications, claims the firm.

The latest evolution of the platform stems from knowledge gained from working with customers on end-product

designs now in production or soon to be released. Gen III devices being released include the TP65H050WS

50mΩ FET and TP65H035WS 35mΩ FET, both available now in standard TO-247 packages, priced at $8.86 and

$11.55 respectively (in 1000-unit quantities). Optimal output ratings are for 1.5-5.0kW applications, depending

on design criteria. Markets include broad industrial applications, data centers, merchant power supplies, and

renewables.

GaNEX | III-N Technology Newsletter No. 65 | 41

Transphorm says that, since it has control over each critical stage of FET development, insight gained during

customer development projects, along with Gen I and Gen II platforms, can be applied to the GaN-on-Si

technology to increase the transistor’s quality, reliability and performance. Data is often gathered that also

informs development techniques that can simplify design complexity, increase safety margin and/or positively

affect power system performance, adds the firm.

Transphorm says research that led to Gen III produced both opportunities: increased benefits now inherent to

the GaN technology itself and new design methods augmenting the FET’s performance. Further, the design and

fabrication innovations enable it to reduce device price.

Also, incorporation of a new MOSFET along with other design modifications enable Gen III devices to deliver:

• an increased threshold voltage (noise immunity) to 4V from 2.1V for Gen II, eliminating the need for a

negative gate drive; and

• a gate reliability rating of ±20V; an 11% increase versus Gen II.

As a result, switching is quieter, and the platform delivers performance improvement at higher current levels

with simple external circuitry, says Transphorm.

Regarding learned design techniques, Transphorm published solutions for oscillation suppression in its app note

0009: ‘Recommended External Circuitry for Transphorm GaN FETs’. Example recommendations include the use

of DC-link RC snubbers and switching-node RC snubbers that add further stability without adverse impact on

efficiency. Notably, the solutions can benefit half-bridge and bridgeless totem-pole PFC topologies.

“It is important to us to evolve our GaN technology based on customer need and real-world experience,” says

Philip Zuk, VP of technical marketing. “Our Gen III FETs exemplify what’s possible when we adhere to that basic

philosophy,” he adds.

“We’ve brought forth a safer, more cost-effective high-voltage GaN FET,” says Dr Yifeng Wu, senior VP of

engineering. “These transistors will be seen by customers as the new power semiconductors delivering

invaluable efficiency, high power handling capability and other performance advantages with ease of use,” he

believes.

Read more

Infineon to start volume production of CoolGaN 400V and 600V e-mode HEMTs by end 2018 Source : SemiconductorToday

In booth #412 (hall 9) at PCIM Europe 2018 (Power Conversion and Intelligent Motion) in Nuremberg, Germany

(5-7 June), Infineon Technologies AG of Munich, Germany is showcasing CoolGaN products in telecom, adapter,

wireless charging and server solutions. With engineering samples available now, the firm announced that it is

starting volume production of CoolGaN products by the end of 2018.

“The next big thing in power management is gallium nitride,” believes Steffen Metzger, Infineon’s senior

director High Voltage Conversion. “The market for GaN has been gaining a strong momentum; the advantages of

using this technology in certain applications are evident,” he adds. “From operating expense and capital

expenditure reduction, through higher power density enabling smaller and lighter designs, to overall system

cost reduction, the benefits are compelling.”

GaNEX | III-N Technology Newsletter No. 65 | 42

During the quality management process not only the CoolGaN device is tested but also its behavior in the

application. At 100ppm (parts per million), predicted lifetime is about 55 years (exceeding the expected lifespan

by 40 years). CoolGaN enables, for example, doubled output power in a given energy storage slot size, freeing

up space and realizing higher efficiency at the same time, says Infineon.

Full production of CoolGaN 400V and 600V enhancement-mode high-electron-mobility transistors (e-mode

HEMTs) will start by end of 2018. CoolGaN 400V will be available in 70mΩ in SMD bottom-side-cooled TO-

leadless and top-side-cooled DSO-20-87 packages. CoolGaN 600V will be available in top-side-cooled DSO-20-87

and bottom-side-cooled DSO-20-85 packages. With 70mΩ and 190mΩ 600V CoolGaN devices in bottom-side-

cooled TO-leadless and DFN 8x8 packages, the 600V CoolGaN portfolio will be complemented.

Read more

France’s ALPHA-RLH bringing RF and microwave cluster delegation to IMS Source : SemiconductorToday

ALPHA - Route des Lasers & des Hyperfréquences (ALPHA-RLH), a French technology cluster specializing in

photonics, microwave and digital technologies, is attending the IEEE International Microwave Symposium (IMS)

for the first time, taking six cluster members to the event in Philadelphia (10–15 June). ALPHA-RLH and Ikalogic,

Inoveos, Cisteme, AirMems and XLIM will be present in booth #2051. AMCAD Engineering will exhibit in booth

#1231.

Several cluster members are presenting technical papers. Members will also display a selection of technologies

that underpin the development of components, subsystems and systems that will become the basis of key

products for radar, telecommunications, defense, space and instrumentation applications.

This year’s IMS highlights the contributions of radio-frequency (RF), microwave (MW) and millimeter-wave

research, development and products to medicine (diagnosis and treatment), telecommunications (5G, Internet-

of-Space) and the Internet of Things (IoT). The cluster supports collaborative innovation projects to increase

member activity in these areas.

New product, live demo and technical presentations

AMCAD Engineering (a provider of measurement and modeling solutions for RF and MW circuits and system

design) is releasing its VISION software platform, a comprehensive methodology to extract a complete and

accurate model that takes into account all observed phenomena. VISION helps to overcome the challenges of RF

systems that are designed to operate with wideband-modulated signals (such as 5G and radar) or with a large

number of circuits (such as active antennas). A live demo of VISION is planned in addition to IVCAD and IQSTAR

demos.

AMCAD will also present three technical papers:

• Track/Title: ‘We2D-2: Investigation of Fast and Slow Charge Trapping Mechanisms of GaN/AlGaN HEMTs

Through Pulsed I-V Measurements and the Associated New Trap Model’, 13 June (10:10-10:30am,

location: 202AB);

• Title: ‘A Robust and Reliable Behavioral Model of High Power GaN HEMTs for RF Doherty Amplifier

Application’, 15 June (11:20-11:40am, location: ARFTG conference, Loews Philadelphia hotel);

GaNEX | III-N Technology Newsletter No. 65 | 43

• Title: ‘Wideband Test Bench Dedicated to Behavioral Modeling of Non Linear RF Blocks with Frequency

Transposition and Memory’, 15 June (11:40am-12:00pm, location: ARFTG conference, Loews

Philadelphia hotel).

Innovations on display

Ikalogic (a specialist in test & measurement devices for embedded system diagnostics and debugging) will

exhibit IkaScope, the first Wi-Fi connected oscilloscope probe. Designed for quick and easy analog

measurements, it enables electronics engineers to work more effectively on the peripheral circuits of

microwave systems (microcontrollers, FPGAs and serial communication between integrated circuits). Ikalogic

will also display its latest logic analyzers offering in-depth digital signal analysis.

Inoveos (a developer and manufacturer of passive microwave components and systems for military and

commercial radar and telecom applications) will exhibit isolators and circulators with unique dual-band and bi-

directional capabilities. Inoveos will also present a technical paper in conjunction with XLIM that demonstrates

an ultra-high-bandwidth Y-junction circulator using the ‘continuous tracking’ operation: Track/Title: ‘We2E-4:

Complete Methodology of Low-Loss Ultra-Wideband Junction Circulator’, 13 June (11–11:20am, location:

203AB).

AirMems (a designer and manufacturer of switches based on RF MEMS technology for defense, space and

telecom applications) will engage with potential customers about the complexity of the future RF electronic

systems and how to meet zero-power-consumption requirements. A space innovation award winner, AirMems’

switches have been in orbit for the last four years.

Cisteme (a technology transfer center) works in collaboration with the XLIM laboratory at the University of

Limoges. At IMS, Cisteme is proposing R&D services for microwave/RF component and system design as well as

wireless applications (IoT, 5G). The center is active in antenna systems, wireless networks, autonomous and

communicating sensor networks (IoT-related), ultra-wideband communication systems, filtering, amplifier

design and optimization, wireless propagation, RF front-end design, electromagnetic characterization of

materials and electromagnetic compatibility.

XLIM (the largest microwave and RF research laboratory in France) is a multi-disciplinary research institute of

CNRS (the French National Research Center). It has expertise in high-power RF non-linear device modeling and

characterization, active and passive microwave circuits, additive manufacturing technologies for microwave and

millimeter wave, MEMS and tunable passive devices, CEM, antennas and phase-array antenna systems. XLIM

maintains links with industry via six joint laboratories working on innovation programs.

Read more

VisIC raises $10m to expand GaN power device portfolio and address more market segments Source : SemiconductorToday

VisIC Technologies Ltd of Nes Ziona, Israel – a fabless developer of power conversion devices based on gallium

nitride (GaN) metal-insulator-semiconductor high-electron-mobility transistors (MISHEMTs) – has closed a $10m

Series D round of financing led by a private investor.

The electrification of automotive vehicles has been growing at an unprecedented pace recently and will

continue to grow for the foreseeable future, says the firm. GaN power devices get the maximum performance

GaNEX | III-N Technology Newsletter No. 65 | 44

out of high-power, high-voltage power conversion systems inside hybrid and electric vehicles (HEV/EV). The

improved size, weight, efficiency and heat management of the on-board charger and the DC/DC converter,

designed with GaN power devices, all contribute to faster charging and longer driving range. High-performance

power supplies for telecom systems and datacenters are using GaN power devices to reach new levels of density

and efficiency, notes VisIC, bringing down the electricity costs of the operators significantly.

“GaN technology opens a new space in power electronics - from shifting the performance envelope up to the

point of new topologies development. We are delighted to see VisIC offering specifically rugged GaN devices

with negligible fast transient dynamic RDSon,” comments Ivan Feno, principal power design engineer at Bel

Power Solutions. “The insulated thermal pad is another welcome feature enabling the increase of the power-

stage reliability and density,” he adds. “Ultimately, 1200V-rated GaN devices might be an attractive alternative

in the 1200V segment dominated by SiC technology today.”

VisIC says that its technology, in combination with ongoing R&D designs by large players in the power

electronics industry, made it possible to close this round of funding on favorable terms.

“With the new funding, we can expand our portfolio further to address more market segments,” says founder &

CEO Tamara Baksht. “Furthermore, we will increase our technical support team to assist our growing worldwide

customer base.”

Read more

Wolfspeed’s adds LDMOS and GaN HEMT products for telecom and radar markets Source : SemiconductorToday

Wolfspeed of Durham, NC, USA — a Cree Company that makes silicon carbide (SiC) power products and GaN-on-

SiC high-electron-mobility transistors (HEMTs) and monolithic microwave integrated circuits (MMICs) — has

launched new LDMOS and GaN HEMT products that are said to enable smaller systems with greater reliability

and efficiency. Wolfspeed’s recent acquisition of the Infineon RF power business expanded its product portfolio,

accelerating its progress in developing innovations for telecom and aerospace/defense applications.

“The acquisition of Infineon’s RF power business has enabled Cree’s Wolfspeed business to transition to the

next level of the RF power semiconductor business,” comments Lance Wilson, research director at ABI Research.

“Historically, Wolfspeed has been a principal player in GaN technology, but the addition of Infineon’s LDMOS

portfolio has put them into the top echelon of high-power RF.”

The acquisition brings LDMOS technology and expertise to Wolfspeed, enabling it to provide the optimal RF

power solution to meet customers’ needs, regardless of the type of technology used, the firm says.

The expansion includes Wolfspeed’s new 28V 2620-2690MHz Asymmetric Doherty Transistor, which is an

LDMOS Doherty transistor that utilizes LD12 technology. This and other LD12 components use a plastic

overmold package that delivers the same performance as open cavity packages, offering significant increases in

efficiency at a lower cost. Such plastic packages can bring significant cost savings to telecom applications, says

Wolfspeed.

“Wolfspeed is committed to supporting the growth of our LDMOS portfolio, as shown by the release of our new

28V Asymmetric Doherty Transistor,” says Gerhard Wolf, Wolfspeed’s VP & general manager of RF. “The

GaNEX | III-N Technology Newsletter No. 65 | 45

expansion of our LDMOS portfolio delivers on the promise of continued innovation for cellular applications, like

improved 4G networks and the shift to 5G networks.”

In the radar market, Wolfspeed is providing aerospace & defense operators better target discrimination and a

longer detection range with the launch of the highest-output-power GaN products on the market, including a

1200W packaged GaN HEMT.

The 1200W GaN HEMT delivers what is claimed to be the highest output power for a GaN L-band radar product

on the market. The device’s high output power enables fewer devices to be used, resulting in simplified system

architectures, lower materials costs, reduced energy consumption and increased system reaction time that is

critical in defense and aerospace settings.

The new LDMOS and GaN HEMT technologies are on display in booth #931 at the IEEE MTT International

Microwave Symposium (IMS 2018) in Philadelphia, MA, USA (10–15 June).

Read more

WIN expands GaN power process capabilities to 0.45µm-gate technology for 5G applications Source : SemiconductorToday

WIN Semiconductors Corp of Taoyuan City, Taiwan – the largest pure-play compound semiconductor wafer

foundry – has expanded its gallium nitride (GaN) process capabilities to include a 0.45µm-gate technology that

supports current and future 5G applications.

The NP45-11 GaN-on-SiC process allows customers to design hybrid Doherty power amplifiers used in 5G

applications including massive MIMO (multiple-input and multiple-output) wireless antenna systems. Similar to

macro-cell applications, MIMO base stations often combine Doherty power amplifiers with linearization

techniques to meet demanding linearity and efficiency specifications of today’s wireless infrastructure.

GaN devices outperform the incumbent LDMOS technology, offering superior efficiency, instantaneous

bandwidth and linearity, particularly in the higher frequency bands utilized in 5G radio access networks, notes

WIN.

Suitable for use in sub-6GHz 5G applications including macro-cell transmitters and MIMO access points, the

NP45-11 technology supports power applications from 100MHz through 6GHz. The discrete transistor process is

environmentally rugged, incorporating advanced moisture protection and meets the JEDEC JESD22-A110 biased

HAST qualification at 55V. Combined with WIN’s, IP3M-01 environmentally rugged high-voltage passive

technology, NP45-11 enables hybrid power amplifiers in a low-cost plastic package, says the firm.

The NP45-11 technology is fabricated on 100mm silicon carbide substrates and operates at a drain bias of 50V.

In the 2.7GHz band, it provides saturated output power of 7W/mm with 18dB linear gain and more than 65%

power-added efficiency (PAE) without harmonic tuning.

“5G radio access networks create several challenges to power amplifier designs used in MIMO systems,” says

senior VP David Danzilio. “High output power and linear efficiency are primary design objectives to meet

performance specifications and lower total cost of ownership,” he adds. “The tradeoff between output power

and linearized efficiency is significant because of the high peak-to-average power ratio employed in today’s

GaNEX | III-N Technology Newsletter No. 65 | 46

wireless modulation schemes. This tradeoff becomes more difficult in 5G applications due to greater

instantaneous bandwidth requirements and higher operating frequency.”

NP45-11 sample kits are available and can be obtained by contacting WIN’s regional sales managers.

WIN is showcasing its compound semiconductor RF and mm-Wave solutions in booth 415 at the IEEE MTT-S

International Microwave Symposium (IMS 2018) in Philadelphia, PA, USA (10-15 June), where David Danzilio is

presenting a paper at the 5G Power Amplifier Technology Workshop on 11 June.

Read more

MACOM showcasing RF and microwave portfolio at IMS Source : SemiconductorToday

In booth #1125 at the IEEE’s International Microwave Symposium (IMS 2018) in the Philadelphia Convention

Center (12–14 June), MACOM Technology Solutions Holdings Inc of Lowell, MA, USA (which makes

semiconductors, components and subassemblies for RF, microwave, millimeter-wave and lightwave

applications) is showcasing its GaN-on-silicon (GaN-on-Si) portfolio, Lightwave Antennas, and other high-

performance MMIC and diode products, including new products optimized for 5G connectivity, wireless

basestations, radar, test & measurement, industrial, scientific and medical RF applications:

Lightwave Antenna solutions: Combining RF coherent beamforming and fiber-to-the-element optical transport

to deliver wideband performance, low latency and improved spectral efficiency;

Enabling next-gen wireless base-stations: GaN-on-Si 60W average power Doherty module;

Front-end modules (FEMs): delivering performance and reliability for wireless networking leveraging

proprietary switching technology and integration;

RF Energy: the first GaN-on-Si-based RF Energy Toolkit;

GaN-on-silicon: Combining manufacturing scale, supply security and surge capacity from STMicroelectronics

with MACOM’s GaN-on-Si RF power products to address mainstream consumer, automotive and wireless base-

station programs;

High-performance RF components: showcasing MACOM’s high-performance MMICs, limiter diode design,

cross-reference tools and application-specific solutions.

MACOM is also participating in sessions throughout IMS, including:

5G Summit: ‘GaN-on-Silicon Transcendent – Enabling The Cost, Integration, and Affordability Challenges to

Make 5G a Reality’ by Anthony Fischetti, 12 June (1pm EST, room 103ABC).

Technical Session: ‘A Novel CAD Probe for Bidirectional Impedance and Stability Analysis’ by Tom Winslow, 13

June (3:30pm EST, room TBD).

Read more

GaNEX | III-N Technology Newsletter No. 65 | 47

GaN Systems showcasing GaN power technologies and customer solutions at PCIM Europe Source : SemiconductorToday

In booth 511, hall 9 (9-511) at PCIM (Power Conversion and Intelligent Motion) Europe 2018 in Nuremberg,

Germany (5–6 June), GaN Systems Inc of Ottawa, Ontario, Canada (a fabless developer of gallium nitride-based

power switching semiconductors for power conversion and control applications) is exhibiting record-setting GaN

transistors and an array of new products, design tools and reference designs that make it easier to develop

power systems, as well as presenting customer demonstrations.

Attendees can learn about the new products, the numerous IC firms that have collaborated with GaN Systems,

and customer implementations spanning the consumer, data center, industrial and automotive market

segments.

Highlights include:

• Record-setting GaN transistors such as the 100V, 120A, 5mΩ GaN E-HEMT device, the highest-current

and power-efficient 100V GaN power transistor and 120A, 650V, 12mΩ GaN E-HEMT, the world’s

highest-current-rated GaN power transistor.

• The new virtual Circuit Simulation Tool, which allows design engineers to evaluate GaN Systems’ devices

in a variety of topologies and compare application conditions before hardware or system construction.

Featuring a simple and intuitive interface, an engineer can quickly and easily tune parameters to suit

their design goals and see the results in real time.

• New reference designs to ease any design challenge, including a 190W LLC + PFC adapter reference

design, optocoupler reference design from Broadcom, and low-DCR, high-frequency controllers from

Analog Devices.

• 3kW evaluation kit for high-efficiency power systems for data-center, automotive, and energy storage

system applications. The evaluation kit enables power engineers to quickly take full advantage of GaN

power transistors in designing improved and novel power systems.

Read more

GaN Systems launches 100W and 300W power amplifiers for wireless charging Source : SemiconductorToday

GaN Systems Inc of Ottawa, Ontario, Canada (a fabless developer of gallium nitride-based power switching

semiconductors for power conversion and control applications) has unveiled two wireless power amplifiers for

wireless charging in high-power consumer, industrial and transport applications: a 100W power amplifier (with

ranges from 70W to 100W) and a 300W power amplifier (with ranges from 150W to 1kW).

GaN Systems is displaying both solutions and demonstrating the 300W amplifier in booth 511, hall 9 (9-511) at

PCIM Europe 2018 (Power Conversion and Intelligent Motion) in Nuremberg, Germany (5–6 June).

GaN Systems says that, as wireless charging goes mainstream, gallium nitride is removing the limitations by

enabling new higher-power system designs that provide the spatial freedom and faster charge times.

The 100W power amplifier [GSWP100W-EVBPA] is suitable for applications in the consumer market for items

such as laptop computers, recreation drones, domestic aide robots, power tools, and fast-charging of multiple

smart phones.

GaNEX | III-N Technology Newsletter No. 65 | 48

The 300W power amplifier [GSWP300W-EVBPA] is targeted for the industrial and transportation markets for

applications that include delivery drones, warehousing robots, medical units, factory automation, contractor

power tools, eBikes, and scooters.

Both power amplifiers have a range of features including current or voltage control, built-in protection circuitry,

EMI filtering, and configurable output power. The amplifiers combine GaN Systems’ power transistors with high-

frequency GaN E-HEMT drivers from pSemi Corp of San Diego, CA, USA – a fabless provider of radio-frequency

integrated circuits (RFICs) based on silicon-on-insulator (SOI).

“Our GaN solutions are creating opportunities for the development of high-power, high-efficiency power

systems in applications such as wireless power transfer and charging,” says Paul Wiener, VP strategic marketing.

“The power ecosystem has changed. There is now availability of high dv/dt level-shifters, fast response IC

sensing and control, low-loss high frequency magnetics, and high-performing GaN transistor and amplifier

capabilities that are enabling smaller, lighter, lower-cost and more efficient power systems.”

Read more

ROHM and GaN Systems collaborate on gallium nitride power semiconductors Source : SemiconductorToday

Power semiconductor maker ROHM of Kyoto, Japan and GaN Systems Inc of Ottawa, Ontario, Canada (a fabless

developer of gallium nitride-based power switching semiconductors for power conversion and control

applications) have announced a GaN power semiconductor collaboration, with the goal of contributing to the

continuing evolution of power electronics.

The strategic partnership leverages GaN Systems’ capabilities in power GaN transistors along with ROHM’s

footprint in semiconductors and resources in the design and manufacture of electronic components. The firms

have agreed to jointly develop form-, fit- and function-compatible products using GaN semiconductor dies in

both GaN Systems’ GaNPX packaging and ROHM’s traditional power semiconductor packaging. GaN Systems and

ROHM say that their customers will have the advantage of having two possible sources for package-compatible

GaN power switches, presenting what is claimed to be the widest selection of dual-sourced GaN devices.

Customers will also benefit from greater access to GaN products and resources globally, especially in Asia (one

of the fastest-growing market for GaN).

In addition, GaN Systems and ROHM will work together on GaN R&D activities to propose new solutions for the

industrial, automotive and consumer electronics fields. Also, to contribute to greater energy savings and

increased power densities in the power electronics market, both firms will continue to collaborate to expand

their line-up of GaN products and broaden the range of choices.

“Gallium nitride has rapidly made its ascent into power electronics applications and this partnership exemplifies

how important GaN has become in a complete power electronics offering,” says GaN Systems’ CEO Jim Witham.

“By combining our joint expertise and capabilities, we’re enabling more businesses to access and experience the

benefits of GaN in achieving higher-power, more efficient, smaller and lighter power electronics,” he adds.

“ROHM has targeted the power device business as one of our growth strategies,” says ROHM Semiconductor’s

senior managing director Katsumi Azuma. “We offer leading-edge products such as SiC (silicon carbide) power

GaNEX | III-N Technology Newsletter No. 65 | 49

devices and provide power solutions that integrate control technologies, including gate drivers that maximize

device performance. We are also developing GaN for next-generation power devices,” he adds. “By leveraging

the superior technologies and expertise of both companies, we are able to accelerate the development of high-

performance solutions to solve the needs of the power market.”

Read more

EPC giving technical presentations on GaN technology and applications at PCIM Europe Source : SemiconductorToday

In hall 7 (stand 539) at PCIM Europe 2018 (Power Conversion and Intelligent Motion) in Nuremberg, Germany

(5–7 June), Efficient Power Conversion Corp (EPC) of El Segundo, CA, USA – which makes enhancement-mode

gallium nitride on silicon (eGaN) power field-effect transistors (FETs) for power management applications – is

exhibiting its latest eGaN FETs and ICs in customers’ end-products enabled by eGaN technology.

EPC will be giving live demonstrations of eGaN devices in several applications including: an eGaN-based 48V–

12V DC–DC power converter for advanced computing and automotive applications; a high-power nanosecond

pulsed eGaN laser driver for LiDAR used in autonomous vehicles; a table that can transfer up to 60W wirelessly;

and a precision motor drive using a high-speed, highly efficient GaN-based module.

Read more

EPC launches Class 4 wireless power demonstration kit Source : SemiconductorToday

Efficient Power Conversion Corp (EPC) of El Segundo, CA, USA – which makes enhancement-mode gallium

nitride on silicon (eGaN) power field-effect transistors (FETs) for power management applications – has made

available a complete Class 4 wireless power demonstration kit.

Transmitting up to 33W while operating at 6.78MHz (the lowest ISM band), the EPC9129 kit comes complete

with two receivers, each with a regulated output − one capable of delivering 5W and a second capable of

delivering 27W at 19V.

The purpose of the demonstration kit is to simplify the evaluation process of using eGaN FETs for highly efficient

wireless power transfer. The EPC9129 utilizes the high-frequency switching capability of EPC GaN transistors to

facilitate wireless power systems with full power efficiency between 80% and 90% under various operating

conditions.

The EPC9129 wireless power system consists of four boards:

• source board (transmitter or power amplifier) EPC9512 featuring the EPC8010, EPC2038 and EPC2019;

• Class 4 AirFuel-compliant source coil (transmit coil);

• Category 5 AirFuel-compatible receive device EPC9514 featuring the EPC2016C; and

• Category 3 AirFuel-compatible receive device EPC9513 featuring the EPC2019.

The popularity of highly resonant wireless power transfer is increasing rapidly, particularly for applications

targeting large power-transmitting surface areas, with the capability to place receiving devices anywhere on the

surface, and the ability to simultaneously power (or charge) multiple devices placed on the surface. The end

GaNEX | III-N Technology Newsletter No. 65 | 50

applications are varied and evolving quickly, from cell-phone charging to powering handheld tablets and laptop

computers. Delivering up to 33W supports all of these applications.

Source (amplifier) board

The source (amplifier) board is a highly efficient zero voltage switching (ZVS) Class-D amplifier configured in an

optional half-bridge topology (for single-ended configuration) or default full-bridge topology (for differential

configuration), and includes the gate driver(s), oscillator and feedback controller for the pre-regulator. This

allows for compliance testing that operates to the AirFuel Class 4 standard over a wide load range. The amplifier

board is available separately as EPC9512 for evaluation in existing customer systems.

Device (receiving) boards

The Category 5 EPC9514 (19V, 27W) and Category 3 EPC9513 (5V, 5W) device or receiving boards included in

the wireless power demonstration kits are also available separately for those who have their own source boards

or who want to work with multiple receiving devices simultaneously. The efficiency of these first-generation

systems is about 87% from input to the transmitter to the output of the receiver (end-to-end) and, with future

improvements in architecture and GaN IC technology, this can reach the 95% range. As with the demonstration

kits, these boards operate to the Airfuel standard, excluding Bluetooth Low Energy (BLE) communications.

With the wide range of efficient receivers that can be used to power anything from lamps to laptops to tablets,

while remaining compatible with cell-phone charging, the system designer now has all the tools needed to

create an entire wireless power, large-area, efficient system, says EPC.

Read more

EpiGaN showcasing RF power and power switching GaN epi techhnology at IMS and PCIM Europe Source : SemiconductorToday

EpiGaN nv of Hasselt, near Antwerp, Belgium - which supplies gallium nitride on silicon (GaN-on-Si) and gallium

nitride on silicon carbide (GaN-on-SiC) epitaxial wafers for power switching, RF and sensor applications – is

highlighting the latest enhancements of its GaN epiwafer solutions for RF power and power switching at the

IEEE International Microwave Symposium (IMS 2018) in Philadelphia, MA, USA (10–15 June) and at PCIM Europe

2018 (Power Conversion and Intelligent Motion) in Nuremberg, Germany (5-7 June). At PCIM Europe, EpiGaN

will exhibit in booth 432 (hall 6).

EpiGaN has previously developed 200mm GaN-on-Si 650V epiwafer solutions for power management systems

that have entered the mainstream CMOS manufacturing lines of silicon-based integrated device manufacturers

(IDMs) and foundries. Recently, for 5G applications, EpiGaN has developed 200mm versions of its HVRF GaN-on-

Si as well as 150mm GaN-on-SiC epiwafer solutions. The firm claims that its RF power products have excellent

dynamic behavior, the highest power densities at mmW ranges and the lowest RF losses (<0.8dB/mm up to

110GHz) for the GaN-on-Si version of its HVRF product family.

EpiGaN says that a key advantage of its GaN-on-Si epiwafer technology is the in-situ silicon nitride (SiN) capping

layer. This feature is said to provide superior surface passivation and device reliability, and enables

contamination-free processing in existing standard silicon CMOS production infrastructures.

GaNEX | III-N Technology Newsletter No. 65 | 51

Also, in-situ SiN structuring allows the use of pure aluminium nitride (AlN) layers as barrier materials, which

results in lower conduction losses and/or the design of smaller-size chips for the same current rating.

For ultimate RF performance in the 5G-related 30GHz and 40GHz millimeter-wave bands, EpiGaN has developed

high-electron-mobility transistor (HEMT) heterostructures featuring pure AlN barrier layers in combination with

an in-situ SiN capping layer to complement the typical AlGaN counterparts. This allows the transistor’s gate to

be located very close to the densely populated channel, maximizing the electrostatic coupling between the two

(i.e. improving gate control). This will result in the far superior RF transistor characteristics needed for 5G MMIC

developments, says EpiGaN.

“EpiGaN has supplied industry-leading GaN epiwafer solutions for power switching and RF power applications to

the global semiconductor industry for several years now,” says co-founder & CEO Dr Marianne Germain. “In

particular, we are proud about our GaN-on-Si epiwafers that show the lowest RF loss in the market up to

100GHz,” she adds. “This is a timely answer to the increasing demands in wireless communication such as the

introduction of 5G and the Internet of Things.”

At PCIM Europe, Germain is participating in a panel discussion ‘GaN - Devices for the Future Design’ at the

show’s Fach Forum, organized by Bodo’s Power Systems (6 June). Also, at the Exhibitor Forum (5 June), chief

marketing officer Dr Markus Behet will give a presentation ‘How GaN Will Dislodge Si-based Technologies in

Power & RF’. In addition, at IMS 2018 on 15 June, chief technology officer Dr Joff Derluy will present

‘Development of Epitaxial Processes for GaN-on-Si for RF Applications’.

Read more

Integra launches fully matched 25W 5-6GHz C-band GaN-on-SiC RF power transistor Source : SemiconductorToday

Integra Technologies Inc (ITI) of El Segundo, CA, USA, which makes high-power RF and microwave transistors

and power amplifier modules, has launched a fully matched, gallium nitride on silicon carbide (GaN/SiC) RF

power transistor suitable for C-band continuous wave (CW) applications.

The IGT5259CW25 is fully matched to 50Ω, operates at the instantaneous frequency range 5.2-5.9GHz, and

offers a minimum of 25W of output power at 36V drain bias. It features 12dB of gain and 48% efficiency under

CW conditions. Negative gate voltage and bias sequencing are required when using the transistor.

Read more

Integra showcasing new RF power devices at IMS 2018 Source : SemiconductorToday

In booth #815 at the IEEE MTT-S International Microwave Symposium (IMS 2018) in Philadelphia, MA, USA (10–

15 June), Integra Technologies Inc (ITI) of El Segundo, CA, USA, which makes high-power RF and microwave

transistors and power amplifier modules, is showcasing several new devices, including an array of new 50Ω (fully

matched) RF power transistors and integrated RF power modules (pallets) for pulsed radar applications.

The IGNP0912L1KW is a 50Ω GaN/SiC (gallium nitride on silicon carbide) RF power module for L-band avionics

systems operating over the instantaneous bandwidth of 0.960-1.215GHz. The integrated amplifier module

GaNEX | III-N Technology Newsletter No. 65 | 52

supplies a minimum of 1000W of peak pulse power, under the conditions of 2.5ms pulse width and 20% duty

cycle, while offering what is claimed to be excellent thermal stability.

The IGT5259L50 is a 50Ω GaN/SiC transistor, offering 50W at 5-6GHz for pulsed C-band radar applications.

The IGN1214L500B is a high-power GaN/SiC high-electron-mobility transistor (HEMT) that supplies 500W at 1.2-

1.4GHz and offers 50V drain bias, 15.5dB gain, and 65% efficiency. The transistor is designed for long-pulse L-

band radar applications.

Read more

Custom MMIC launches GaAs and GaN MMICs at IMS 2018 Source : SemiconductorToday

At the IEEE MTT International Microwave Symposium (IMS 2018) in Philadelphia, MA, USA (10–15 June),

monolithic microwave integrated circuit developer Custom MMIC of Westford, MA, USA has launched the

CMD283C3 ultra-low-noise amplifier (ULNA) MMIC, which provides a 0.6dB noise figure, outperforming all other

LNA MMICs, it is claimed, and rivaling discrete component implementations. It operates over a frequency range

of 2-6GHz (S- and C-band) and has output third-order intercept point (IP3) of +26dBm.

Also being introduced are four members of the firm’s new gallium arsenide (GaAs) MMIC digital attenuator

family. The CMD279 and CMD280 operate up to 30GHz with 5-bit control. Attenuation range is up to 15.5dB.

Two 2-bit attenuators, the DC-35GHz CMD281 and DC-40GHz CMD282, offer coarser control in 2dB and 4dB

steps, respectively. All four devices offer input IP3 of +42dBm.

The latest distributed amplifier, the DC-20GHz CMD249P5, offers a positive gain slope with nominal 12dB gain.

The GaAs device features saturated power output (Psat) of +30dBm and output IP3 of +38dBm.

Custom MMIC also continues to enhance its line of low-phase-noise amplifiers (LPNAs). Responding to customer

requests to assist in reducing unwanted phase noise and improve signal integrity and target acquisition in

military radar systems, these LPNAs operate at up to 40GHz and offer low phase noise performance down to -

165dBc/Hz at 10kHz offset. They can serve as local oscillator (LO) drivers or receiver amplifiers in a variety of

phased-array radar, electronic warfare (EW), military radio, instrumentation, and aerospace and space

communication designs.

Further MMIC releases on the firm’s horizon include more ultra-low-noise amplifiers and digital attenuators, as

well as broadband distributed power amplifiers and gallium nitride (GaN) mixers.

Read more

StratEdge features packages for extreme demands of GaN and GaAs devices at IMS Source : SemiconductorToday

In booth 1649 at the IEEE’s International Microwave Symposium (IMS 2018) at the Pennsylvania Convention

Center in Philadelphia (12-14 June), StratEdge of San Diego, CA, USA (which designs and manufactures packages

and provides chip assembly & test services for microwave, millimeter-wave and high-speed digital devices) is

featuring its new line of packages that meet the extreme demands of gallium nitride (GaN) and gallium arsenide

GaNEX | III-N Technology Newsletter No. 65 | 53

(GaAs) devices. StratEdge packages meet the critical requirements of the telecom, mixed signal, VSAT,

broadband wireless, satellite, military, test & measurement, automotive, down-hole, and MEMS markets.

StratEdge is showcasing its complete line of post-fired and molded ceramic semiconductor packages operating

from DC to 63+GHz. These packages have electrical transition designs that ensure low electrical losses and

operate efficiently, even at the highest frequencies. All packages are lead-free and most meet RoHS and WEEE

standards. In addition, StratEdge offers complete automated assembly & test services for these packages,

including gold-tin solder die attach.

“5G and its high-power infrastructure, the Internet of Things, and advanced cellular technologies requiring RF

and microwave frequencies will make package selection critical,” comments president Tim Going. “IMS is a great

opportunity for those involved to visit our booth and discuss their packaging requirements.”

Read more

Anokiwave expands design center in Billerica, doubling footprint with new lab and office space Source : SemiconductorToday

Anokiwave Inc of San Diego, CA, USA – which provides highly integrated silicon core chips and III-V front-end

integrated circuits for millimeter-wave (mmW) markets and active antenna-based solutions – has expanded its

design center in Billerica, MA into a newly remodeled office to accommodate its rapid growth in highly

integrated IC solutions for 5G communications, mobile satellite communications, and aerospace & defense

markets that require millimetre-wave active antenna-based solutions.

With the expansion, Anokiwave has more than doubled its lab area for design validation and pilot-production

activities and now features the capability for pilot production of mmW wafer-level chip-scale packaged (WLCSP)

ICs within the facility.

The updated modern open-concept floor plan includes a low-noise environment suitable for engineering teams,

energy-efficient LED lights, with areas to accommodate larger groups including ‘huddle rooms’ for employees to

utilize for meetings and brain-storming sessions. Anokiwave’s initiative to go green with motion sensor lights

and updated electronics has continued to be a priority.

“Anokiwave’s continued product leadership in the rapidly evolving mmW active antenna market required a

larger space to accommodate our growing staff,” says chief operating officer Carl Frank. “The highly integrated

silicon IC design expertise and innovative culture is at the core of Anokiwave’s mission of enabling a new world,”

says founder & chief technology officer Nitin Jain. “Our team continues to demonstrate leadership in the market

with exciting new product launches planned over the next few months in our key 5G, SatCom, and radar

markets.”

Read more

GaNEX | III-N Technology Newsletter No. 65 | 54

Anokiwave introduces second set of intelligent gain block ICs in family of mmWave multi-market solutions Source : SemiconductorToday

Anokiwave Inc of San Diego, CA, USA – which provides highly integrated silicon core chips and III-V front-end

integrated circuits for millimeter-wave (mmW) markets and active antenna-based solutions – is releasing a set

of two new ICs in a family of multi-function microwave and millimeter-wave silicon ICs, offering complete

transmit/receive functionality with active gain and phase control. The new ‘Intelligent Gain Block’ (IGB) IC family

offers versatile RF blocks that can be used in a wide range of applications including SatCom, radar, 5G

communications and sensing.

Similarly to the previously released ICs in the IGB family (AWMF-0116 and AWMF-0117), The AWMF-0141 and

AWMF-0143 provide a power amplifier (PA), low-noise amplifier (LNA), 6-bit gain and phase control and a

transmit/receive (T/R) switch, all integrated into a single IC operating in the Ku- and Ka-bands. Removing the T/R

switch allows more flexibility and improved output power and noise figure.

The AWMF-0141 operates at 10.5-16GHz, providing +13.5dBm power output during transmit and 1.5dB noise

figure during receive. The AWMF-0143 operates at 26-30GHz with +13dBm of power output during transmit and

3.0dB noise figure during receive. Both ICs provide 31.5dB of dynamic range and are packaged in a 2.5mm x

2.5mm wafer-level chip-scale package (WLCSP).

“The unique design of these ICs allows them to be used for highly integrated millimeter-wave arrays (such as 5G,

SatCom or phased-array radars) or as a replacement of single-function discrete blocks,” says VP of sales

Abhishek Kapoor. “With this new product family, designers can now use the same IC for multiple functions

across the RF signal chain, have increased control using a software interface, and provide equivalent or better

performance than traditional discrete gallium arsenide (GaAs) ICs,” he adds. “We see these as the versatile new

intelligent gain blocks of the microwave and millimeter-wave world.”

For ease of adoption of the technology and capabilities, Anokiwave offers evaluation kits that include boards

with the IC, USB-SPI interface module with drivers, and all required cables. Pilot-production deliveries are

available now.

Read more

Anokiwave adds 24/26GHz IC to new family supporting 3GPP-compliant mmW 5G equipment Source : SemiconductorToday

Anokiwave Inc of San Diego, CA, USA – which provides highly integrated silicon core chips and III-V front-end

integrated circuits for communications and radar applications needing millimeter-wave (mmW) active antenna-

based solutions – has launched the next product in its new family of 5G-Gen 2 silicon quad core ICs that enable

3GPP-compliant base stations. With the worldwide release of the new 24/26GHz AWMF-0139 IC, the 5G-Gen 2

IC family now supports all major 5G mmW bands – 24/26GHz, 28GHz and 37/39GHz – and is part of Anokiwave’s

on-going strategy to enable the commercialization of 5G mmW systems with silicon ICs.

The AWMF-0139 is a highly integrated silicon IC packaged in a wafer-level chip-scale package (WLCSP), easily

fitting within the typical 5.77mm lattice spacing at 26GHz. It operates at 24.25-27.5GHz, supports four radiating

elements, and includes gain and phase controls for analog RF beam steering. Anokiwave’s patent-pending IP

GaNEX | III-N Technology Newsletter No. 65 | 55

blocks implemented in silicon technology are said to enable low-cost hybrid beam forming with high energy

efficiency and 5G fast beam steering.

“5G operating frequencies around the world are converging on three mmW bands – 24/26GHz, 28GHz/ and

37/39GHz,” says chief systems architect David Corman. “As the push to roll out 5G networks is proceeding at full

speed, Anokiwave is executing on an aggressive strategy to deliver 5G solutions with industry-first ICs at these

important bands,” he adds. “Today’s announcement of the complete family of ICs that both enable 3GPP

compliance and cover the important 5G bands is an essential step that allows network operators to roll out 5G

coverage in earnest.”

Anokiwave offers evaluation kits for ease of adoption of the technology and capabilities. The kits include boards

with the IC, USB-SPI interface module with drivers, and all required cables. Pilot production deliveries of the

AWMF-0139 are available now.

Read more

Sumitomo to Feature GaN HEMTs for Radar Applications at IMS 2018 Source : EverythingRF

Sumitomo IMSSumitomo Electric Industries, Ltd and its group company Sumitomo Electric Device Innovations

USA, Inc. (SEDU) are participating in the 2018 International Microwave Symposium (IMS 2018) being held in

Philadelphia, USA from 10-15 June. SEDU is a leading provider of advanced RF, wireless and optical

communications solutions. Their latest offerings include S-band and X-band GaN HEMTs targeted at radar

applications in the 3.1-3.5 GHz and 9.0-10 GHz frequency bands.

Today's radars provide large detection areas and advanced early detection, while reducing their size and weight.

GaN is a proven and reliable semiconductor material used for radar applications. Having high power output and

wide bandwidth, GaN is expected to improve the performance of radars. Sumitomo Electric will showcase new

GaN-HEMT products, SGN3135-500H-R and SGC0910-300A-R, at the preeminent conference.

Features of SGN3135-500H-R for the S-band

• High output power: Psat = 570 W (Typ.)

• High gain: GP = 11.6 dB (Typ.)

• High power added efficiency: 58% (Typ.)

• Frequency band: 3.1 to 3.5 GHz

• Impedance matched Zin/Zout = 50 ohm

• Hermetically sealed IV package

Features of SGC0910-300A-R for the X-band

• High output Power: Psat = 340 W (Typ.)

• High gain: GP = 9.3 dB (Typ.)

• High power added efficiency: 35% (Typ.)

• Frequency band: 9.0 to 10.0 GHz

• Impedance matched Zin/Zout = 50 ohm

• Hermetically sealed package

GaNEX | III-N Technology Newsletter No. 65 | 56

The SGN3135-500H-R and SGC0910-300A-R were designed by drawing on Sumitomo Electric's established GaN

process technology. Sumitomo Electric is a leader in producing GaN-related products and continues to lead in

technological innovation to offer low-cost high-performance devices for next-generation radar systems.

Visit them at Booth 1141 at IMS 2018.

Read more

GaN-on-Silicon Transistor Comparison 2018 Source : I-micronews

Dive deep into the technology and cost of GaN-on-silicon HEMTs from EPC, Transphorm, GaN Systems,

Panasonic and Texas Instruments.

The market for GaN high-electron-mobility transistors (HEMTs) is very appealing, drawing in ever more

manufacturers. This factor lowers prices, making GaN devices good competitors for the currently-used silicon-

based power switching transistors such as MOSFETs and IGBTs.

GaNEX | III-N Technology Newsletter No. 65 | 57

Nevertheless, the technical details are still unsettled, with every manufacturer presenting its own solution to die

design and packaging integration. This brings fierce competition, which will accelerate technical innovation and

further lower prices. Moreover, GaN business models are still very different, and in the future we will see supply

chain restructuring driven by the main cost factors. Manufacturers propose different approaches for epitaxy,

gate structure, device design, and packaging, all focused on solving the problems linked to GaN’s intrinsic

properties and its integration with silicon.

In this report, System Plus Consulting presents an overview of the state of the art of GaN-on-silicon HEMTs to

highlight the differences in design and manufacturing processes, and their impact on device size and production

cost. We have analysed different devices at low and medium voltage from EPC, Texas Instruments, Panasonic,

GaN Systems and Transphorm. The report includes detailed optical, Scanning Electron Microscope and

Transmission Electron Microscope pictures of the packaging, the transistor structures and the epitaxy.

This report provides an estimated production cost for the integrated circuit gate driver, transistor, and package.

It also compares the different components available on the market.

Read more

GaNEX | III-N Technology Newsletter No. 65 | 58

OPTOELECTRONICS

Plessey’s CTO presenting at Display Week following UK National Technology Award Source : SemiconductorToday

At the Society for Information Display (SID) Display Week 2018 event in Los Angeles on 24 May, Dr Keith

Strickland - chief technology officer of Plessey Semiconductors Ltd of Plymouth, UK - is presenting a paper on

the future of microLED displays using next-generation technologies and highlighting the benefits of Plessey’s

proprietary gallium nitride on silicon (GaN-on-Si) technology.

“Holding a growing number of patents for the implementation of GaN-on-Si technology in microLED display

design and manufacturing, Plessey is very close to announcing some major partnerships and the launch of new

photonic solutions to enable OEMs to develop truly wearable augmented reality devices,” says Strickland.

Plessey’s participation at Display Week 2018 (20-25 May) follows the firm winning the Tech Company of the

Year category at the National Technology Awards, which celebrates technology pioneers and encourages

excellence in the UK. Winners were revealed at an awards ceremony on 17 May at the Waldorf Hilton hotel in

London with over 300 guests in attendance.

Read more

Vuzix announces partnership to develop next generation AR smart glasses using Plessey microLED technology Source : I-micronews

Vuzix®, ("Vuzix" or, the "Company"), a supplier of Smart Glasses and Augmented Reality (AR) technologies and

products for the consumer and enterprise markets, is pleased to announce that the Company is partnering with

Plessey Semiconductor, a developer of award-winning optoelectronic solutions. The two companies are

partnering to develop advanced display engines for Vuzix waveguide optics to enable next generation AR Smart

Glasses. The combination of Vuzix' extensive expertise and IP in smart glasses and waveguide optic technologies

along with Plessey's microLED light source product family, Quanta-Brite™ will be the basis for a new generation

of AR Smart Glasses with the sleekest form factors to date.

In the development of its next-generation waveguide based products, Vuzix has selected Plessey's microLED-

based Quanta-Brite™ light engine, which delivers extremely high efficiency with significant improvements in

lumen output compared to other light sources currently available on the market. The smaller and more efficient

microLED based Quanta-Brite™ light engine will not only result in less energy consumption and improved

battery life, but also enables Vuzix to cut a significant amount of volume from the display engine in future

generations of our waveguide based smart glasses, while at the same time delivering improved optical

performance at a reduced cost.

GaNEX | III-N Technology Newsletter No. 65 | 59

blade alexa

Quanta-Brite™ is based on Plessey's advanced and proprietary gallium-nitride-on-silicon (GaN-on-Si) technology,

with an integrated monolithic array of RGB pixels with advanced micro-optical elements to create a bright,

largely collimated and highly uniform light source for the illumination in advanced display engines. The resulting

optical system is up to 50% smaller, lighter, simpler and cheaper than incumbent solutions and the high

performance microLED emitters combined with minimal optical system losses result is significantly increased

power efficiency. Size, weight and power reduction are key considerations in AR/MR wearables. Quanta-Brite™

has been designed specifically for the next generation of Vuzix personal display systems.

The combination of Vuzix' recently announced collaboration with Qualcomm around the Snapdragon XR1

platform and Plessey's Quanta-Brite™ microLED™ technology along with our next generation waveguide optics

should enable Vuzix to develop powerful AR smart glasses in form factors nearly indistinguishable from regular

eyeglasses. These new AR Glasses, expected to be introduced in 2019, should lead the market in terms of

processing power designed for AR, overall imaging performance and most importantly style,

"This development with Vuzix, the leading provider of next-generation augmented reality glasses, is a significant

endorsement of Plessey's GaN-on-silicon microLED approach," said Dr Keith Strickland, Chief Technology Officer

at Plessey. "Monolithic microLED technology is fast emerging as the only one that can provide high luminance in

a very small form factor with minimal energy consumption, necessary for reducing costs and enabling

lightweight battery-powered products for a range of emerging consumer and industrial applications."

"Plessey's Quanta-Brite™ microLED™ technology can be a major enabler of the future of augmented reality,"

said Vuzix President and CEO Paul Travers. "As well as delivering high-efficiency, low-power and small-size

illumination capabilities, the very high level of luminescence of the Quanta-Brite™ light source can also enable

the development of end products with a sleeker form factor, which is a key attribute of our waveguide based

Smart Glasses and critical to mass market adoption."

Read more

GaNEX | III-N Technology Newsletter No. 65 | 60

Kulicke & Soffa partners with Rohinni on design, commercialization and distribution of micro- and mini-LED technologies Source : SemiconductorToday

Singapore-based chip assembly & packaging equipment and materials supplier Kulicke and Soffa Industries Inc

(K&S) has entered into a licensing agreement with Rohinni LLC of Coeur d'Alene, ID, USA (which has developed a

proprietary method for transferring semiconductor devices) to facilitate the design, commercialization and

distribution of next-generation micro- and mini-LED solutions, which it says have the potential to enhance the

performance, improve the efficiency and reduce the size of existing lighting technologies.

Significant high-volume end-markets including automotive, display, consumer electronics and general lighting

are expected to drive adoption. While micro- and mini-LED benefits are compelling, high-volume production

challenges must be addressed prior to widespread market adoption, K&S adds.

Rohinni has developed solutions that directly address such production challenges, enabling greater design

flexibility in end-use applications. In parallel, it has also established a network of partnerships in several key

segments poised to benefit from this technology.

Kulicke & Soffa says that its existing market positions, R&D competencies, supply chain and manufacturing

capabilities provide scale to further extend Rohinni’s leadership and its effort in driving adoption of new LED

technologies.

“K&S has recently taken a much more proactive approach in targeting and identifying complementary

partnerships with a clear path to value creation,” says Chan Pin Chong, senior VP of the Wedge Bond and

EA/APMR business unit.

“Our team has spent the past several years developing precise, high-speed placement technologies for micro-

and mini-LED products,” notes Rohinni’s CEO Matt Gerber. “This agreement with K&S provides capabilities to

quickly scale development and global production,” he adds.

LCD displays incorporating these latest developments in LED backlighting technologies for High-Dynamic-Range

(HDR) viewing are significantly brighter than organic light-emitting diodes (OLEDs). To produce an HDR LCD

display with over 10,000 LEDs in a backlight assembly requires a completely new generation of high-speed

production technologies, says K&S. With an estimated 220 million square meters of flat-panel displays

estimated to be produced in 2018, the growth potential of new backlighting technologies is significant. The

unique and complementary contributions of both K&S and Rohinni are expected to accelerate global adoption

of micro- and mini-LED-based solutions.

Read more

Epistar files US patent infringement lawsuit against V-TAC USA Source : SemiconductorToday

Taiwan-based LED epitaxial wafer and chip manufacturer Epistar Corp has filed a patent infringement lawsuit

against V-TAC USA Corp in the United States District Court for the Central District of California. The complaint

asserts that V-TAC’s LED filament bulbs infringe seven Epistar patents and seeks injunctive relief to halt further

sale of the infringing products.

GaNEX | III-N Technology Newsletter No. 65 | 61

Epistar’s complaint alleges that the V-TAC’s LED filament bulbs such as the VT-5115D Light Bulbs (P/N: 215), VT-

5100D Light Bulbs (P/N: 200) and VT-5133 Light Bulbs (P/N: 283) infringe one or more claims of Epistar’s US

patent numbers 6,346,771 (‘High Power LED Lamp’), 7,489,068 (‘Light Emitting Device’), 7,560,738 (‘Light-

Emitting Diode Array Having An Adhesive Layer’), 8,240,881 (‘Light Emitting Device Package’), 9,065,022 (‘Light

Emitting Apparatus’), 9,488,321 (‘Illumination Device With Inclined Light Emitting Element Disposed On A

Transparent Substrate’), and 9,664,340 (‘Light Emitting Device’).

Read more

Epistar Progresses Mini LED Production in Q3 Source : LEDinside

During Display Week 2018 held by SID (Society for Information Display), LEDinside noticed that many

manufacturers have demonstrated products applying Mini LED panels. Leading companies had released Mini

LED backlight products in difference sizes, including display VR devices, mobile phones, notebooks, automotive

display and TVs.

Taiwanese LED chip maker Epistar announced its Mini LED technology development and started to connect its

clients for collaboration of various products including smartphone, laptop and indoor signage last year. The

company has been working on Mini LED backlights application and is preparing production for clients on the

third quarter 2018 and by the fourth quarter, Mini LED application could be found in the market. It is said that

Epistar is processing Mini LED orders for Huawei for about 1 million devices.

(Image: LEDinside)

Meanwhile, Epistar also progresses Mini LED-based applications on larger size displays and is trying to speed up

the manufacturing of 27 inch panel. The company expects to launch the display the latest by 2019 and to break

through the current obstacles in mass production to increase the production by 2020 in an investor conference.

GaNEX | III-N Technology Newsletter No. 65 | 62

For Micro LED, the company said its application on TVs and wearable devices will be demonstrated by the

second half of 2018, however, due to the limitation of technology and high cost, Epistar forecasts that Micro

LED-based products might be showcased during 2023-2025.

Currently the company runs faster with Mini LED and estimated that Mini LED would take 30-40% of the

revenue by 2020.

Read more

Osram boosts efficiency of green LEDs by 40% Source : SemiconductorToday

Osram Opto Semiconductors GmbH of Regensburg, Germany has succeeded in reducing the typical forward

voltage by about 600mV to 2.6V (at a power density of 45A/cm2) in its indium gallium nitride (InGaN)-based

green direct-emitting LEDs. With a simultaneous increase in optical output power, efficiency can be instantly

improved by up to 40% compared to predecessor products across the firm’s entire UX:3 portfolio. The

significant drop in light output (the ‘green gap’ phenomenon) exhibited by green LEDs has often been the cause

of efficiency problems and high costs in customer applications.

The benefits can be considerable, particularly for applications in which red, blue and green LEDs used in

combination. Because all three colors now have a voltage of less than 3V, the size of the drivers (previously

designed for higher maximum voltages) can now be smaller. This in turn reduces both dissipative power loss and

costs. The crucial factors in increasing efficiency were improved charge carrier transport and optimized material

quality in the epitaxial layers.

At 350mA, 1mm2 UX:3 chips achieve efficiencies of 175lm/W and higher at wavelengths around 530nm with the

new technology. Absolute light output in excess of 300lm at a pumping current of 1A opens up new applications,

says Osram Opto.

“Until recently, these efficiency values seemed unattainable for green direct-emitting InGaN LEDs,” says project

manager Adam Bauer. “We are now moving into areas that up to now have been achievable only with

phosphor-conversion emitters but with significantly reduced spectral quality,” he adds. “Thanks to the success

of our development team we have been able to drastically reduce the green gap phenomenon.”

The team is now working on further improvements that offer potential that has become evident as a result of

the recent findings.

Read more

Luminus adds white LEDs to horticulture portfolio spanning UV to Far Red Source : SemiconductorToday

Luminus Devices Inc of Sunnyvale, CA, USA – which designs and makes LEDs and solid-state light sources for the

global illumination market – has expanded its horticulture LED portfolio with new SST-20 series white LEDs to

complement its range of discrete wavelengths from UVA (365nm) to Far Red (730nm).

Incorporating white light in horticulture fixtures provides illumination in the greenhouse and makes it easier to

observe crops for signs of disease. Also, in many cases, white LEDs can replace blue LEDs as they provide similar

GaNEX | III-N Technology Newsletter No. 65 | 63

photosynthetic photon flux (PPF), potentially reducing production costs. With a flexible range spanning 2700–

7000K, users can now select the light most appropriate to their needs.

“The need for improved crop yields and more sustainable food supplies is more important than ever and our

horticulture LED advances enable innovative luminaires that directly address the market’s needs,” says Yves

Bertic, senior director of global product marketing.

As the horticulture and farming research community discover productivity and crop quality gains through

wavelength and spectrum engineering, Luminus says it is continuing to expand its range by adding new

wavelengths to its portfolio so that growers and farmers can maximize production yields, become more

sustainable and reduce costs.

“With this addition to our SST series, we now offer a comprehensive horticulture product portfolio that delivers

the highest performance and efficacy with competitive lead times of 12 weeks or less,” says Bertic.

Luminus horticulture LED products are globally available in volume directly or through the firm’s distribution

network.

Read more

Luminus enters UV-C LED disinfection and sterilization market with two 280nm emitters Source : SemiconductorToday

Luminus Devices Inc of Sunnyvale, CA, USA – which designs and makes LEDs and solid-state light sources for the

global illumination market – has expanded its ultraviolet (UV) LED portfolio with two new 280nm devices for the

medical and health & well-being markets.

The standard-footprint 3535 surface-mount emitter is a 350mA device with peak output up to 60mW. The

second ultra-compact emitter is 1.3mm by 1.3mm and only 0.85mm tall, and delivers 3mW at 20mA and peak

output of 11mW at 100mA.

“Air, surface and water disinfection markets will see a significant number of new products and new product

categories over the next 36 months,” says Stephane Bellosguardo, VP of specialty lighting marketing. “Just as

the computer industry was driven by ever smaller and faster processors, so will be the innovation in markets like

air and water purification with miniature products like our 1313 UV-C LED.”

The new UV-C LEDs are just the latest additions to a UV portfolio that offers both surface-mount devices and

modules in the UV-A spectrum for horticulture, curing, additive manufacturing and medical instrumentation

applications.

“UV-LED-based industrial applications are already growing rapidly and represent an increasingly important

segment of our non-visible specialty products alongside infra-red emitters,” says Bellosguardo.

Read more

GaNEX | III-N Technology Newsletter No. 65 | 64

Luminus’ spectrally tuned LED light sources target new market opportunities Source : SemiconductorToday

Luminus Devices Inc of Sunnyvale, CA, USA – which designs and makes LEDs and solid-state light sources for the

global illumination market – has released its third proprietary spectral technology, PerfectWhite, which is said to

closely replicate the visual characteristics of halogen lamps (3000K).

Luminus says that, compared with halogen, PerfectWhite was preferred by lighting designers in testing at both

the Light + Building and Lightfair events. Though the spectrums are a virtual match – Luminus filled the cyan gap

– PerfectWhite’s color point is slightly below the black-body locus and, as a result, there is no green/yellow tint

that is common to halogen. A better halogen has long been a wish of the lighting design community, and

PerfectWhite delivers without infrared, without green/yellow tint, and without ultraviolet radiation, says

Luminus.

“The spectral characteristics of light from a halogen lamp are what make it so appealing, particularly in

hospitality and museum applications,” says Tom Jory, VP of illumination. “Unlike other full-spectrum LEDs that

emit harmful near-UV radiation, PerfectWhite delivers the visual effect of a halogen lamp by filling the cyan gap

that exists in traditional LED technology,” he adds.

Luminus’ portfolio of unique LED spectrums also includes AccuWhite and Sensus spectral technologies, which

can be applied to virtually any of the firm’s chip-on-board (COB) LEDs.

AccuWhite is spectrally engineered to maximize color rendering index (CRI) performance, and it delivers the

firm’s highest color-rendering products, with a guaranteed CRI minimum of 95 and a typical CRI of 98. With

lighting designers and visual display managers continuing to seek the very highest CRI and TM-30-15 ratings for

the most demanding interior lighting applications, AccuWhite LEDs offer TM-30-15 values as high as 95 for Rf

(fidelity) and 100 for Rg (gamut) while still achieving luminous efficacy as high as 125 lumens per watt at a case

temperature of 85°C.

Sensus spectral technology addresses demands in retails shops to inspire shoppers with light that creates more

dramatic, vibrant and exciting environments where whites are whiter, and saturated colors like blue and red are

richer and more vibrant, says Luminus. Sensus’ engineered spectrums in 3000K and 3500K produce a large

gamut area index (GAI BB15 as high as 120) and chromaticity below the black-body curve, allowing people to

see pure, bright whites and deeper colors with greater contrast. While other LEDs might also produce pure

whites, Luminus claims that Sensus achieves this without sacrificing efficacy, as demonstrated with up to

148lm/W at 85°C.

“Our three spectral technologies serve as the foundation for additional spectral tuning that is specifically

targeted at human centric lighting,” says Jory. “Though there’s much still to be discovered, we are already

working with industry partners to provide light that serves dual purposes of illuminating beautifully so people

can see well and being healthy for people.”

Read more

GaNEX | III-N Technology Newsletter No. 65 | 65

Samsung Ready to Release Micro LED TVs in Q3 Source : LEDinside

Samsung demonstrated “The Wall”, the new giant 16inch Micro LED TV in CES 2018 and is now planning to

release the products into the market by third quarter this year. According to the report of Korea Times, a senior

company executive said Samsung Electronics will debut TVs using Micro LED technology commercially the

soonest in the third quarter in 2018.

(Image: Samsung)

Details about the new Micro LED TV including its size and selling price are still unrevealed but one Samsung

executive said it could be “flexible” and customized as Micro LED panels could be spliced to fit any requested

size.

Samsung is targeting the market in the United State and the Middle East, and plan to sell it as a premium

product. As the cost for producing extra-large size LCD and OLED panels is very high, Micro LED display become

more competitive in the segment of large screen as extra-large display could be made by splicing.

"As Samsung is increasingly asked to explore and navigate new opportunities amid flattening demand for

premium TVs from general consumers, what we have to do is to make Micro LED TVs successful and to have

them with enhanced features for corporate and non-consumer clients," said the executive.

However, mass transfer of Micro LED chips on substrate is still one big obstacle in manufacturing and therefore

making mass production a main challenge if Samsung plan to commercialize Micro LED TV.

Read more

GaNEX | III-N Technology Newsletter No. 65 | 66

The World First Micro LED chip on PCB Introduced by ITRI Source : LEDinside

At COMPUTEX TAIPEI 2018, ITRI demonstrated the new Micro LED signage module which transfers Micro LED

chip directly on PCB substrate. This achievement suggests that the display module has a great potential to

reduce the cost and can be applied on products like video wall and indoor signage through splicing.

CLEDIS, Micro LED display introduced by SONY in 2017, applied similar technology using PCB substrate as

backplane, but the Micron-size chips needed to be packaged before transferring to PCB as the substrate was not

smooth enough for direct transfer. The solution introduced by ITRI in COMPUTEX 2018 has overcome the

difficulty and provide possibility to produce Micro LED display module with lower cost in the future.

According to LEDinside, with the technology, the cost of the module could be reduced up to 30% comparing to

fine-pitch display, thus it could change the commercial display market once the technology becomes more

mature.

ITRI partners with Macroblock, Unimicron and PlayNitride to realize the production of Ultra-Fine Pitch Micro

LED Signage Module by 2019

The product displayed by ITRI was developed together with Taiwanese companies, Macroblock, Unimicron and

PlayNitride. Macroblck , LED driver IC Company, is responsible for passive matrix driver to drive and correct

Micron-size LED chips. Then Unimicron produces the requested PCB substrate. And the semiconductor

producer, PlayNitride, helps to mass produce the Micro LED chips designed by ITRI.

ITRI cooperated with the three producers and developed passive matrix driver “Ultra-Fine Pitch Micro LED

Signage Module for Displays”, the size of LED chip die is between 50 µm - 80 µm, the pitch is below 800 µm, and

GaNEX | III-N Technology Newsletter No. 65 | 67

the module size is 6 cm x 6 cm with definition 80 x 80 pixels. It could be combined and connected to fit different

size video wall and indoor signage.

However, currently there are still some technical obstacles to be overcome. Ultra-Fine Pitch Micro LED Signage

Module can display colors but not yet “’R’GB full color” due to the material limitation of red LED and the color is

easily effected after transferred because of the roughness of conventional PCB substrate. These issues stress the

complication of directly transferring Micro LED to PCB substrate and the difficulty to control the uniformity.

Currently the team is working to break through the restrictions.

Macroblock will be in charge to commercialize Ultra-Fine Pitch Micro LED Signage Module and to carry out the

request skills into the application of signage for the market. LEDinside speculate that by 2019, Micro LED signage

will appear in our life.

Transparent Micro LED Signage Module

There is another transparent Micro LED signage module demonstrated in COMPUTEX 2018, the specification is

the same as Ultra-Fine Pitch Micro LED Signage Module but the transparent signage module is based on ultra-

thin glass substrate, on which RGB full color can be displayed. Also, as Micro LED takes smaller portion of the

pixel area, the transparency could reach 60% and higher, plus the ultra-lightness, this transparent Micro LED

signage module is suit for outdoor area and to be applied on windows, interactive screens and vending

machines.

Read more

GaNEX | III-N Technology Newsletter No. 65 | 68

OTHER

GaN Crystal Firm Up For Sale Source : CompoundSemiconductor

Ammono, the Warsaw company behind an innovative method of making nearly perfect GaN crystals, is up for

auction with an initial price of €3.5 million.

Instead of growing crystals using vapour deposition (which is the approach taken by other GaN substrate

makers), Ammono grows them under high heat and pressure. It then slices them salami style to be turned into 2

inch substrates on which semiconductors are grown.

These near perfect crystals offer the possibility of higher yields of violet lasers, more efficient GaN-based power

handling chips, and even better performing LEDs.

Ammono has been in and out of receivership since 2015. The Japanese firm Nichia, which, became a financial

backer back in 1999, is still involved as a minority shareholder. But the current situation has been brought about

by conflict with the latest investor, according to Ammono’s president Robert Dwilinski, who pioneered the

development of the firm’s GaN crystal growth process.

Last year, the Polish Academy of Sciences' Institute of High Pressure Physics (IHPP PAS) became Ammono's

‘leaseholder’. The tenancy, established by the Polish Ministry of Science and Higher Education, was to enable a

close cooperation between the groups involved in ammonothermal and HVPE crystallisation of GaN.

Ammono will be sold with all assets including thousands of crystal seeds, autoclaves and crystal machining

equipment, characterisation tools like high resolution X-ray diffractometer, AFM, and patents. Offers must be

submitted by the 15th June 2018.

Read more

BluGlass raises AUD$9.2m in share placement and offers AUD$5m share purchase plan Source : SemiconductorToday

BluGlass Ltd of Silverwater, Australia – which was spun off from the III-nitride department of Macquarie

University in 2005 – has received commitments from institutional, professional and private investors to

purchase 24,864,865 fully paid ordinary shares at AUD$0.37 per share to raise AUD$9.2m under a placement

with Wilsons Corporate Finance Ltd and Stifel Nicolaus Europe Ltd acting as joint lead managers and

bookrunners.

Issue of the placement shares will be made by BluGlass using its existing placement capacity under ASX Listing

Rule 7.1 and, accordingly, shareholder approval is not required. Settlement of the placement is expected to

occur on 24 May and the placement shares are expected to be allotted on 25 May.

“We are very pleased to see the significant cornerstone support from global institutional funds,” says managing

director Giles Bourne. “These funds have invested alongside domestic institutional and retail investors.”

GaNEX | III-N Technology Newsletter No. 65 | 69

BluGlass will also undertake a share purchase plan (SPP) under which registered shareholders (as of 18 May)

with addresses in Australia and New Zealand can subscribe for either AUD$2000, AUD$5000, AUD$7000,

AUD$10,000 or AUD$15,000 worth of new fully paid ordinary shares at the same issue price (free of brokerage

and transaction costs) to raise up to about AUD$5m. The share purchase plan offer opens on 22 May and is

expected to close at 7pm (Sydney time) on 12 June (subject to extension of the timetable by BluGlass).

The issue price of AUD$0.37 per share under the placement and the share purchase plan represents an 8.6%

discount to the closing share price on 16 May and an 11.4% discount to BluGlass’ 5-day volume-weighed

average price (VWAP) ending on 16 May.

BluGlass is commercializing its proprietary low-temperature remote-plasma chemical vapor deposition (RPCVD)

process for manufacturing indium gallium nitride (InGaN)-based LEDs, power electronics and solar cells, offering

advantages including higher performance and lower cost, it is claimed.

The funds raised under the placement and share purchase plan (after costs) are intended to be used to:

• acquire additional metal-organic chemical vapor deposition (MOCVD) equipment to build and

demonstrate applications by retrofitting MOCVD equipment with RPCVD on commercial platforms;

• undertake a major facilities upgrade to expand existing infrastructure to assist in accelerating RPCVD

development; and

• strengthen BluGlass’ balance sheet to exploit market opportunities and help to fund the planned

increase in activity.

“Proceeds from the placement will enable BluGlass to expedite its technical and commercial goals with our

collaborative partners and deliver commercial outcomes for our proprietary RPCVD technology,” says Bourne.

Read more

Eta Research develops free-standing GaN substrates Source : SemiconductorToday

Eta Research of Shanghai, China, which was founded in 2015 to develop free-standing gallium nitride (GaN)

wafers, says that it is now able to produce 100mm GaN wafers.

Eta uses HVPE to produce GaN wafers. A key process technology is the method of GaN separation from the

substrate. Eta has developed a unique method, not used by other companies in the industry it is claimed, which

is said to greatly improve the yields and enhance the crystal quality. Additionally, the firm uses high-quality

polishing equipment purchased from a vendor that has experience of polishing GaN wafers.

The current production equipment can produce entire uncracked 100mm GaN wafers but, due to edge effects,

the finished wafers must be cut to a smaller size. The firm will soon offer 2” and 3” GaN wafers for sale. It plans

to retool to a larger size to produce 100mm finished GaN wafers by 2019.

Eta’s R&D lab is located in Shanghai, but construction is already underway on a high-capacity production facility

in Tongling, Anhui Province.

“Our goal is to improve the energy efficiency and performance of GaN-based devices by using GaN substrates,”

says CEO Troy Baker. “For that to happen on a large scale, GaN substrates must become widely available for a

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reasonable price,” he adds. “We intend to control the cost through our new high-yield separation process and

the large scale of our new factory, while delivering a product with the characteristics – size, crystal quality,

lattice curvature, electrical conductivity, and surface finish – that our customers require.”

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Veeco’s revenue grows 14% in Q1 to $158.6m, driven by MOCVD system shipments to China Source : SemiconductorToday

For first-quarter 2018, epitaxial deposition and process equipment maker Veeco Instruments Inc of Plainview,

NY, USA has reported a seventh consecutive quarter of revenue growth, to $158.6m (well above the midpoint of

the $140-165m guidance). This is up 14% on $139.7m last quarter (adjusted from $143.4m after adopting the

ASC 606 revenue recognition standard on 1 January) and up 68% on $94.5m a year ago.

“2018 is off to a great start with strong sequential and year-over-year revenue growth,” says chairman & CEO

John R. Peeler. “Sales growth in the first quarter was driven primarily by shipments of our lithography systems

into the advanced packaging market, and shipments of MOCVD systems for LED applications.”

Of total revenue, the LED Lighting, Display and Compound Semiconductor segment hence comprised 57%,

growing to $90m, reflecting strong 2018 opening metal-organic chemical vapor deposition (MOCVD) backlog

(delivering systems to five customers in China).

The Advanced Packaging, MEMS & RF Filter segment jumped from 9% of revenue last quarter to 17% (more

than doubling to $27m), as Veeco saw MEMS device makers add to their etch production capacity and tier-1

OSAT (outsourced assembly & test) customers add capacity for fan-out wafer-level packaging and copper pillar

applications (shipping multiple lithography tools).

The Front-End Semiconductor segment (formerly part of the Scientific & Industrial segment, before the

acquisition in May 2017 of lithography, laser-processing and inspection system maker Ultratech Inc of San Jose,

CA, USA) fell to $9m, comprising 6% of revenue (down from 9%). However, this includes revenue from STT-

MRAM and 3D wafer inspection systems (two areas of growth for Veeco).

The Scientific & Industrial segment was flat at $32m (mainly sales for data storage as well as optical coatings),

falling from 24% of revenue last quarter to 20%.

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Geographically, of total revenue, China rebounded further, from just 18% last quarter to 47% (including 39%

from MOCVD sales for blue LEDs), while the USA remained at 15%, Europe, Middle East & Africa (EMEA) fell

from 14% to 10%, and the rest of the world (including Photonics, RF Device and Advanced Packaging revenue in

Taiwan, Korea and Japan) fell from 53% to 28%.

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Riber receives repeat order for research MBE system from IIT Bombay Source : SemiconductorToday

Riber S.A. of Bezons, France - which manufactures molecular beam epitaxy (MBE) systems as well as

evaporation sources and effusion cells – has received an order from the Indian Institute of Technology (IIT)

Bombay for a model Compact 21T research MBE system (for delivery in 2019).

The system will contribute to further strengthening IIT Bombay’s research capabilities for developing new

optoelectronic devices using quantum dot lasers.

This repeat order is the fourth Riber system operated at IIT Bombay. Riber says that this commercial success is

part of its continued expansion into India's growing market, where it already has an installed base of 16 systems

(64% of the total in India).

Read more

GaNEX | III-N Technology Newsletter No. 65 | 72

PATENT APPLICATIONS

More than 210 new patent applications were published in April 2018.

Other patent applicants: Nagoya University, Ngk Insulators, Nikkiso, North Sea Weide Electronic Technology, Sanan Optoelectronics, Semiconductor Components Industries, Seoul Viosys, Sony, Stanley Electric, Sumitomo Chemical, Texas Instruments, Tohoku University, Toyoda Gosei, University Of California, VisIC Technology, Wuhan University, Xiamen San An Integrated Circuit, ABB Schweiz, Advantest, Air Water, Akoustis, Anhui Yinxin New Energy Technology, Asahi Chemical Industry, Beijing Huajin Chuangwei Electronics, Beijing University Of Posts &Telecommunications, Bmw - Bayerische Motoren Werke, Buddha Dongshan Metal Products, CEA - Commissariat A L Energie Atomique Et Aux

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Energies Alternatives, Chengdu Hiwafer Technology, China Institute Of Electronic Product Reliability & Environment Test, Chip Foundation Technology, Coorstek, Cree, Dalian Core Technology, Delta Electronics, Dongguan Haoshun Precision Technology, Ecole Polytechnique Federal De Lausanne Epfl, Exagan, Fairchild Semiconductor, Flinders University Of South Australia, Focus Lightings Science & Technology, Founder, Fraunhofer, Fujian Fulian Integrated Circuit, Fujian Trillion Yuan Photoelectric, Fujitsu, Funai Electric, Genicom, Global Energy Internet Institute, Globalfoundries, Goverment Of The Us Secretary Of The Navy, Guangdong Institute Of Semiconductor Industrial Technology, Guangdong Ruisen Semiconductor Technology, Hangzhou Zhenlei Microwave Technology, Hong Kong University Of Science And Technology, HRL Laboratories, Huawei Technologies, Institute For Energy Application Technology, Institute Of Microelectronics Chinese Academy Of Sciences, Jilin University, Jimei University, Jinggangshan Electrical Appliance, Kuwata, LG Electronics, Liebherr Hausgeraete, Lumeova, Lumileds, Meijo University, MIT - Massachusetts Institute Of Technology, Mitsubishi Chemical, Nanjing Changfeng Aerospace Electronic Equipment, Nanjing Guobo Electronics, Nanjing Yinmao Microelectronic Manufacturing, Nantong Tongfang Semiconductor, National Chung Shan Institute Of Science & Technology, Nexperia, Nichia, Nichicon, etc.

Notable new patent applications

Semiconductor devices with multiple channels and three-dimensional electrodes Publication Number: WO2018087728 Patent Applicant: Ecole Polytechnique Federale De Lausanne (EPFL) (Switzerland) The present invention relates, for example, to a semiconductor structure containing multiple parallel channels in which several parallel conductive channels are formed within the semiconductor structure. Electric contact or electrostatic control over all these channels is done by three-dimensional electrode structures. The multiple channel structure with three-dimensional electrodes can be applied to semiconductors devices such as field effect transistors, diodes, and other similar electronic or quantum-effect devices. This structure is practical for materials where multiple parallel conduction channels can be formed, such as in III-V semiconductors. Ill-Nitride semiconductors with such structures are described which can lead to increased power density, reduced on-resistance and improved device performance, in addition to reducing dynamic on-resistance, and improving the stability of their threshold voltage and reliability.

Power circuit switching device having a passive protection circuit Publication Number: WO2018096263, FR3059490 Patent Applicant: ExaGaN (France) The invention relates to a power circuit switching device comprising two switching terminals, a high voltage depletion mode transistor and a low voltage enhancement mode transistor arranged in series between the two switching terminals, a first terminal for receiving a switching signal and electrically connected via a driver circuit to the gate of the high voltage transistor, and a second terminal for receiving a control signal and electrically connected to the gate of the low voltage transistor. The device comprises a normally-on protection circuit electrically connected between the second terminal and the gate of the high voltage transistor to keep the high voltage transistor in an off-state when the driver circuit is not electrically powered.

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Broad wavelength band light-emitting element and a method of fabricating the light emitting element broad wavelength band Publication Number: JP2018078232 Patent Applicant: NGK Insulators (Japan) PROBLEM TO BE SOLVED: Emission peak wavelength in the vicinity of the wide band high emission intensity, and can be produced without going through complicated steps to realize a light emitting element. SOLUTION: And methods for making the light emitting element, and a plurality of GaN single-crystal particles, the GaN single-crystal particles are c axis direction of the inclination angle with respect to the substrate normal in the frequency distribution of the angle of inclination 0° when the frequency value of the cumulative frequency value from the integrating sequence of the entire 80% at a tilt angle and a cumulative 80% inclination angle 10° or more polycrystalline GaN substrate and a step of preparing, on a polycrystalline GaN substrate, GaN of the n-type dopant is doped with a predetermined n-type conductive layer is formed in such a manner that a step, n type conductive layer on, InxGa1-xN first composition 1 GaN layer and the second unit 2 unit layers are alternately laminated repeatedly by a multiple quantum well structure active layer having a step of forming, on the active layer, GaN p-type dopant of predetermined doped p-type conductive layer becomes a step of forming a, that a user.

Micro-light emitting diode (LED) fabrication by layer transfer Publication Number: US2018138357, WO2018087704 Patent Applicant: QMAT (USA) Embodiments relate to fabricating a micro-Light Emitting Diode (LED) structure utilizing layer-transferred material. In particular, high quality Gallium Nitride (GaN) is grown upon a donor substrate, utilizing techniques such as Hydride Vapor Phase Epitaxy (HVPE). Exemplary donor substrates can comprise GaN, AlN, SiC, sapphire, and/or single crystal silicon - e.g., (111). The large relative thickness (e.g., ~10's of μm) of GaN grown in this manner, significantly reduces (e.g., to about 2-3x106 cm-2) Threading Dislocation Densities (TDDs) present in the material. This allows the cleaved grown GaN material to be well-suited for transfer and incorporation into a micro-LED structure operating at high brightness under low current/heat generation conditions.

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GaN-HEMT with Si-CMOS monolithic integrated method Publication Number: CN108054143 Patent Applicant: No.55 Institute of China Electronics Science & Technology Group (China) The present invention discloses a GaN-HEMT with Si-CMOS monolithic integration of the method, comprising the steps of: cleaning the Si-CMOS wafer and the temporary carrier sheet surface, and performing a temporary bond; of the Si-CMOS substrate is thinned polishing; in the Si-CMOS back etched out of a hole in communication with each other; through-hole interconnected and etch the dielectric layer is grown in a window; in the vias and Si-CMOS substrate backside plating filling metal; preparing a patterned gold bump; in the GaN-HEMT preparing a patterned metal bumps on the wafer; of the GaN-HEMT and a Si-CMOS wafer bond alignment; removing the temporary carrier web and a temporary binder material, the resulting GaN-HEMT with Si-CMOS monolithic wafer. The present invention implements GaN-HEMT with Si-CMOS monolithic integration of high-density, interconnection density on the order of the lift, and solving the heat dissipation problem of high power devices high-density integration.

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