Formation mechanism of PLD-derived Pb(Mg1/3Nb2/3)O3 - … · 1 Piezoelectrics U. Gabor, Advanced Materials Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, SLOVENIA

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Urška Gabor Student Speech Contest

Jožef Stefan Institute, Advanced Materials Department, Jamova 39, 1000 Ljubljana, SLOVENIA

Supervisors: M. Spreitzer, D. Suvorov

Formation mechanism of PLD-derivedPb(Mg1/3Nb2/3)O3 - PbTiO3 thin films

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Piezoelectrics

U. Gabor, Advanced Materials Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, SLOVENIA ECerS 2017

Transformers

Piezoelectric microelectromechanical systems (piezoMEMS)

Bearings

Water shafts

Vibration energy harvesting

0

5

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2017 2018 2019 2020 2021 2022

Rev

enu

e (U

SD b

illi

on

s)

2017 - 2022 MEMS market forecast

Status of the MEMS Industry report, Yole Développement, May 2017

Main device features:

NO battery (no waste) TRUE wireless SMALL size LONG lifetime HIGH temperature resistance

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En

erg

y H

arv

estin

g F

igu

re o

f M

erit e

231,f/ε

0ε r

(GP

a)

Tra

nsve

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pie

zo

ele

ctr

ic c

oe

ffic

ien

t -e

31,f

(C/m

2)

Pb-based materials still dominate the field of piezoelectrics, except in some niche aplications

Why Pb(Mg1/3Nb2/3)O3-PbTiO3 ?

PMN-PT exhibits excellent piezoelectric properties useful for sensors, actuators, energy harvesters, etc.

Epitaxial PMN-PT exhibits properties superior to PZT

Potential for further improvement!

S.H. Baek et al., Science, 334, 958 (2011)

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Pulsed-laser deposition (PLD)

Simple and fast

Flexible/versatile

Large pressure range

Precise control of the growth rate

For many materials the compositionof the target is preserved in thetransfer to the substrate surface

Scalable – large wafers

Why PLD?

Pulsed laser deposition system at JSI10 × 10 mm

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https://www.sintef.no/globalassets/project/piezovolume/publications/industrial-fabrication-of-piezomems_tyholdt.pdf

8-inch (200 mm)

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Si

SrTiO3 (STO)

(Electrode)

Active layer

Electrode

Integration with silicon

But we first need to study the phenomena on a research system

Si

SrTiO3

Buffer layer (1/2 monolayer Sr/Si(001) surface)


Pulsed-laser deposition (PLD)

Simple and fast

Flexible/versatile

Large pressure range

Precise control of the growth rate

For many materials the composition of the target is preserved in the transfer to the substrate surface

Challenges:

PMN-PT

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Multicomponent material

Volatility of Pb → lead-deficient pyrochlore

- Meticulous control of the growth conditions does not always suffice!

How much lead excess?

Targets with different amounts of Pb excess and PMN:PT ratio

Non-stoichiometric transfer and shifted morphotropic phase boundary (MPB)

PMN-25PTPMN-33PT

PMN-40PT

10 mol. %15 mol. %

20 mol. %

- Pb-loss compensation through the use of Pb-rich targets

Challenges:


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Longitudinal (d33) mode

ElectrodesPiezoelectricSrTiO3 buffer layerSi or SS cantilever

Interdigitated electrodes

Design of experiments

Higher electromechanical coupling Higher achievable voltages due to the

higher piezoelectric constant and adjustableelectrode spacings

Transverse (d31) mode

Parallel-plate electrodes

Most commonly used

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SrTiO3

LaNiO3

PMN-PT

PbO excess required:

NOPbO excess required::

YESPbO excess required:

YES

SrTiO3

PMN-PT

SrTiO3

SrRuO3

PMN-PT

3.2 %

2.0 %

5.2 %

LNO strongly stabilizes the perovskite phase

PMN-40PT / STO

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20 mol. % 10 mol. %

SrTiO3

LaNiO3

PMN-PT6

PbO excess required:

NOPbO excess required::

YESPbO excess required:

YES

SrTiO3

PMN-PT

SrTiO3

SrRuO3

PMN-PT

3.2 %

2.0 %

5.2 %

LNO strongly stabilizes the perovskite phase

PMN-40PT / STO

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20 mol. % 10 mol. %

• Broad (00l)pc peak splitting indicates stronginhomogeneity – not MPB

• Peak splitting absent in films prepared from targetswithout Pb-excess, but also observed in bulk ceramicsamples

(002) STO

(002)pc

PMN-PT

Oxygen deficiency is not the reason for the

splitting – shown byexperiments with O2/Ar

mixture

• Process pressure strongly influences phase purity

PMN-40PT + 20 mol. % PbO / STO

Qz×10000(r.l.u.)

4000

3900

3800

3700

3600

3500

Qx×10000(r.l.u.)-400 -300 -200 -100 0 100 200 300

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1 0 0 n m1 0 0 n m

5 n m5 n m

STO

PMN-PT

STO

PMN-PT

0.13 mbar

0.27 mbar

PMN-40PT + 20 mol. % PbO / STO

A B

Antiphase boundaries

[100]

TEM cross-sections

Interface

STO

PMN-PT

[100]

Sharp!

- Defects form close to the interface…

… and propagate throughout the films

- In both samples

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PFM litography (in-situ poling)

Amplitude piezo image Phase imageTopography-Height

L digit lengthw digit widthg interdigital spacing

Nb-doped STO

Interdigital electrodes(IDE)

Longitudinal design

Transverse design

Parallel plate capacitor structurewith Au top electrodes

LNO electrodes

εf permittivity of the film

A film prepared at 0.13 mbarB film prepared at 0.27 mbar

AB

0

500

1000

1500

2000

εf

Piezoelectric coefficients low – films are clamped!

Good domain mobility

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Conclusions

Model system for multicomponent

materials

Plasma-plume dynamics (pressure) extremely important!

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http://enpiezo.ijs.si/

Thank you!

http://www-k9.ijs.si/

Prof. Danilo Suvorov Dr. Matjaž Spreitzer

• Damjan Vengust, Advanced Materials Department, Jožef Stefan Institute

• David Fabijan, Advanced Materials Department, Jožef Stefan Institute

• Dr. Daniel Díaz Fernandez, Advanced Materials Department, Jožef Stefan Institute

• Tjaša Parkelj, Advanced Materials Department, Jožef Stefan Institute

• Dr. Hana Uršič, Electronic Ceramics, Jožef Stefan Institute

• Dr. Elena Tchernychova, Department of Materials Chemisty, National Institute of Chemistry

Documents

Formation mechanism of PLD-derived Pb(Mg1/3Nb2/3)O3 - … · 1 Piezoelectrics U. Gabor, Advanced Materials Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, SLOVENIA