Two-Dimensional van der Waals Materials Based Nonvolatile Memory Field-Effect

Transistors

Do Kyung Hwang

Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology (KIST)

dkhwang@kist.re.kr

2-D van der Waals Materials beyond Graphene

2

Transition Metal Dichalcogenide (TMD) Black phosphorous (BP)

M X

Ti, Hf, Zr

S, Se, Te

V, Nb, Ta

Mo, W

Tc, Re

Pd, Pt

They are hot materials for future semiconductor.

They have very high carrier mobility.

They show a quantum confinement effect .

Why 2D vdWs Nanosheets ?

O. Lopez-Sanchez et al. Nat. Nanotechnol. 8, 497 (2013)

B. Radisavljevic et al. ACS Nano 5, 9934 (2011)

L. Li et al. Nat. Nanotechnol. 9, 372 (2014)

Y. Deng et al. ACS Nano 8, 8292 (2014)

MoS2 and BP ferroelectric FETs MoS2 FeFETs BP FeFETs

VD

Load RExt(10 MΩ)

VIN

VOUTBFM 02

BP FeFET unit device and Resistive-load inverter circuit

p-BP and n-MoS2 CMOS inverter circuit

MoS2 FeFET with graphene S/D

Au top gateP(VDF-TrFE) (220 nm)

MoS2 nanoflake

GrapheneSource

GrapheneDrain

SiO2 (285 nm) / p+-Si

[ ]CC

F F

H H

[ ]CC

F F

F H

70 30

-(VDF)- -(TrFE)-

P(VDF-TrFE) copolymer15 um

Gr Gr

Au/Ti Au/Ti

MoS2(W/L: ~ 0.5)

MoS2 FETs with Graphene S/D

4

x-axis

y-axis

5um

Gr1Gr2

MoS2

Au/Ti

Au/Ti

SiO2/p+Si

(a) (b)

E0

qХMoS2(= 4.0eV)

ECEF

EV

0.3eV

qФGr (= 4.5eV)

i

qФMoS2(= 4.3eV)

E0

ECEF

EVi

n

qФSB,Gr < EC-EF+∆qФ

∆qФ = qФGr-qФMoS2

qФMoS2(= 4.3eV)

qФGr (= 4.5eV)

-50 -40 -30 -20 -10 0 10 20 30 40 5010-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

Gate Voltage (V)

Dra

in C

urre

nt (A

)

Au/Ti SD electrode Graphene SD electrode

-1.0 -0.5 0.0 0.5 1.0-15

-10

-5

0

5

10

15

-15

-10

-5

0

5

10

15

Drain Voltage (V)

Dra

in C

urre

nt (µ

A)

Au/Ti SD electrode Graphene SD electrode

-0.5 0.0 0.5-1.0

-0.5

0.0

0.5

1.0

-1.0

-0.5

0.0

0.5

1.0

VD (V)

I D(µ

A)

VD = 1V

VG = -50~50, 10V step

IG

(a)

(c)

-1.0 -0.5 0.0 0.5 1.0-20

-15

-10

-5

0

5

10

15

20

-20

-15

-10

-5

0

5

10

15

20

Drain Voltage (V)

Dra

in C

urre

nt (µ

A)

Au/Ti SD electrode Graphene SD electrode

-50 -40 -30 -20 -10 0 10 20 30 40 5010-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

Au/Ti SD electrode Graphene SD electrode

Gate Voltage (V)

Dra

in C

urre

nt (A

)

-0.5 0.0 0.5-1.0

-0.5

0.0

0.5

1.0

-1.0

-0.5

0.0

0.5

1.0

I D(µ

A)

VD (V)

(b)

(d)

VD = 1V

VG = -50~50, 10V step

IG

Direct imprinting method Transfer and output characteristics

Graphene S/D electrode for MoS2

Y. T. Lee et al. Small 10, 2356 (2014)

Graphene S/D electrode: superior ohmic or ON/OFF

current behavior to those of Au/Ti due to modulated

work function according to applied gate bias

MoS2 based ferroelectric field-effect transistors (FeFETs)

5

Au top gateP(VDF-TrFE) (220 nm)

MoS2 nanoflake

GrapheneSource

GrapheneDrain

SiO2 (285 nm) / p+-Si

[ ]CC

F F

H H

[ ]CC

F F

F H

70 30

-(VDF)- -(TrFE)-

P(VDF-TrFE) copolymer15 um

Gr Gr

Au/Ti Au/Ti

MoS2(W/L: ~ 0.5)

Y. T. Lee et al. J. Korean Phys. Soc. Inpress (2015)

MoS2 FeFET with P(VDF-TrFE)

0 1 2 3 4 5 6 7 8 9 1010-14

10-12

10-10

10-8

10-6

10-4

Drai

n Cu

rrent

(A)

Time (min)

Erase

Program

0V

-20V

1sRead

Floating gate

1s+20V

0V ReadFloating gate

VD=0.1 V

0 10 20 30 40 50 6010-1410-1210-1010-8

-20-10

01020

I D (A)

Time (s)

V G Pul

se (V

)

Erase

Program VD=0.1 V

+ 18.7V, 1 s (Program)

-18.7 V, 1 s (Erase)

0 V, 4 s(read)

-20 -10 0 10 2010-1410-1310-1210-1110-1010-910-810-710-610-510-4

Line

ar M

obili

ty (c

m2 V-1

s-1)

Drai

n Cu

rrent

(A)

Gate Voltage (V)

0306090120150180210

VD=1.0 V 175 cm2/Vs

Erase

Program

1s+20V

0V

0V

-20V

1s

Dynamic and Retention properties

MoS2 FeFET : Highest mobility of 175 cm2/V s , memory

window > 15 V, proper dynamic and retention properties

BP based FeFETs and Memory circuits (1)

6

-20 -10 0 10 2010-14

10-12

10-10

10-8

10-6

- ID (

A)

VG (V)

VD = -0.1 V

Program

Erase1s

+20V

0V

0V

-20V

1s

VG

VD

1 10 100 100010-12

10-10

10-8

10-6

10-4- I

D (A)

Time (s)

0V

-20V

1s ReadFloating gate

VD = -0.1 V

1s+20V

0V Read

Program

EraseFloating gate

Y. T. Lee et al. ACS Nano DOI: 10.1021/acsnano.5b04592 (2015)

-20 -10 0 10 200

20406080

100120140

µ lin (c

m2 V-1

s-1)

VG (V)

VD = -0.1 VBFM 01131 cm2V-1s-1

Memory window

: 15 V

Memory on-off

: 106

Mobility

: 131 cm2/Vs

BP FeFET with P(VDF-TrFE) Linear Mobility

Memory static and retention properties

BP based FeFETs and Memory circuits (2)

7

VDD

Load RExt(10 MΩ)

VIN

VOUTBFM 02

W/L: ~0.55

W/L: ~1.06

3rd BP flake

MoS2 flake

Common gate

Y. T. Lee et al. ACS Nano DOI: 10.1021/acsnano.5b04592 (2015)

VDD = -0.1 V

VIN

VOUT

VDD

RExt10 MΩ

BFM 02Program

Erase1s

+20V

0V

0V

-20V

1s

BFM 02

15 V

1 10 100 10000.000.020.040.060.080.100.12

- VOU

T (V)

Time (s)

0V

-20V

1s ReadFloating gate

Program

Erase1s+20V

0V ReadFloating gate

VDD = -0.1 VBFM 02

Resistive-load inverter circuit p-BP and n-MoS2 CMOS inverter circuit

-20 -10 0 10 2010-14

10-12

10-10

10-8

10-6

10-4

VBG=0 V VBG=5 V VBG=10 V VBG=15 V VBG=20 V

Abs (

I D) (A

)

VTG (V)

VD = ±0.1 VBFM 03

MFM 03

-20 -10 0 10 200.000.020.040.060.080.100.12

V OUT (

V)

VIN (V)

Program

Erase 1s+20V

0V

0V

-20V

1s

VBG=20 V, VDD = 0.1 V

VDD

VOUT

BFM 03

MFMVBG

GND

VIN

0 100 200 300 4000.000.020.040.060.080.100.12

Time (s)V OU

T (V)

0V

-20V

1s ReadVIN : Floating

Program

Erase1s

+20V

0V ReadVIN : Floating

VBG=20 V, VDD = 0.1 V

02468

10

Heig

ht (n

m)

0.0 0.4 0.8 1.2 1.6 2.0048

1216

Distance (µm)

Heig

ht (n

m)

~ 7.2 nm

~ 12.5 nm

BP

MoS2

Summary

8

We demonstrate the high performance MoS2 based nonvolatile memory

transistors

High performance, clear memory window, proper dynamic and retention properties

Papers: Y. T. Lee et al. Small 10, 2356 (2014) and J. Korean Phys. Soc Inpress (2015)

We also demonstrate few-layered BP-based nonvolatile memory transistors and

more advanced memory circuits.

Unit device, resistive-load inverter, and CMOS inverter combined with MoS2

Paper: Y. T. Lee et al. ACS Nano DOI: 10.1021/acsnano.5b04592 (2015)