Feasible Mott FET: Concept, Obstacle, and Future

1

Isao H. Inoue

Feasible Mott FET: Concept, Obstacles, and Future

National Institute of Advanced Industrial Science & Technology (AIST) (Tsukuba, Japan)

[email protected] http://staff.aist.go.jp/i.inoue/ECRYS-2014 @ Cargèse, Corse, France 15 August 2014

Tem

p

Ordered State

Classical Critical Point

Quantum criticality

Quantum Critical Point

Physical Parameters(Pressure, Magnetic field,

Carrier number, etc.)

3


Tem

p

Ordered State

Classical Critical Point

Super

CeCu2Si2Te

mp

Antiferro

Pressure

Quantum Critical Point

Physical Parameters

Quantum critical phenomena

Pressure

Super

UGe2

Tem

p

Ferro

4


Phys. Parameters are alwayseither Pressure or Mag. Field

UGe2

Saxena et al., Nature 406, 587 (2000) [ Coleman, Nature 406, 580 (2000) ]

Ferro

Super

Pressure

Tem

p

Yuan et al., Science 302, 2104 (2003)

CeCu2Si2

AFSuper

Pressure

Tem

p

5


Continuous and reversible control of electronic states on the verge

of the quantum critical point

Randomness-free method: quantum critical phenomena is

so vulnerable to disorders

6

For QCP study, we need …

[email protected] http://staff.aist.go.jp/i.inoue/ECRYS-2014 @ Cargèse, Corse, France 15 August 2014 7

Electrostatic Carrier Doping

9


Electrostatic carrier doping

Mott transistor Exotic phonomena

10

Miniaturisation limit of conventional Si MOSFET

Switching energy of memory and logic devices


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ƕƲƷǑƏƳˮፗ᧙ƴƋǔƔǛƠƯǈƨƍŵ�

�

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䋰䋱

䉣䊈䊦䉩䊷

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Ed

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䋼䋰䋾

䋼䋱䋾

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㫅䋾䋾㪈䋾䌾㪈㪇

⥄↱䉣䊈䊦䉩䊷㪝㪔㪯䊶㪰

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ᩓןưƋǔŵɥᡓƷɋ ɌƷᛯཞ७ǛਤưƖǔƜƱŴƓǑƼƜǕǒ

ɟƭƷཞ७ƕഏƷെƷཞ७ƴࢨ᪪ǛɨƑƯምǛᘍƑǔƜƱƕŴᛯȇȐǤ

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ƱɌƷ᧓ǛᨠƯǔȐȪǢƕᙲưƋǔŵȐȪǢƷٻƖƞƸŴȦȋȃȈȁ

ȣȸǸƴݣƠƯ ʆɯ ǑǓǋٻƖƍᙲƕƋǓŴᨥƸƓǑƦ ɐɈɌɋ ᙲưƋ

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༏ႎƴᘍƏƱƦƷǛˤƏŵཞ७ǛܭܤƞƤǔƴƸŴƜƷǨȍȫǮȸ

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䉣䊈䊦䉩䊷

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Ed

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n

㪋㪅䉣䊈䊦䉩䊷䈱ଏ⛎䈫ᢔㅺ䈱ᯏ᭴䈏ᔅⷐ

㪜㪹䋾䋾㫂㪫䋾䌾㪌䋭㪈㪇㩷㫂㪫㪔㩷㪇㪅㪈䋭㪇㪅㪉㩷㪼㪭

㫅䋾䋾㪈䋾䌾㪈㪇

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ɎɈɍ ƴᅆƠƨǑƏƴŴɍ ȖȸȫˊૠᛯȇȐǤǹưƸŴᡫŴ ɋ Ɍ

Ʒᛯཞ७ǛƋǔཞ७٭ૠ ɳ ưᘙƢŵƜƷཞ७٭ૠƸ༏щܖႎƳཋưŴ

ƳཋࢫƣƜǕƱσ ɴ ƕƋǔŵɞɨɪɮ ƷئӳŴɳŴɴ ƸƦǕƧǕᩓᒵƱ

ᩓןưƋǔŵɥᡓƷɋ ɌƷᛯཞ७ǛਤưƖǔƜƱŴƓǑƼƜǕǒ

ɟƭƷཞ७ƕഏƷെƷཞ७ƴࢨ᪪ǛɨƑƯምǛᘍƑǔƜƱƕŴᛯȇȐǤ

ǹѣ˺ƷᙲˑưƋǔŵƜǕƸ༏щܖႎƳǷǹȆȠƱƠƯѣƍƯƍǔƷưŴ ɋ

ƱɌƷ᧓ǛᨠƯǔȐȪǢƕᙲưƋǔŵȐȪǢƷٻƖƞƸŴȦȋȃȈȁ

ȣȸǸƴݣƠƯ ʆɯ ǑǓǋٻƖƍᙲƕƋǓŴᨥƸƓǑƦ ɐɈɌɋ ᙲưƋ

ǔŵཞ७٭ૠƷ٭ᲢምᲣƴƸŴǨȍȫǮȸƕᙲưŴǨȍȫǮȸ٭੭Ǜ

༏ႎƴᘍƏƱƦƷǛˤƏŵཞ७ǛܭܤƞƤǔƴƸŴƜƷǨȍȫǮȸ

n >> 1

switching energynEd >> 100kBT ( = 2.6 eV )

Ed = Eb + dissipation

each <0> and <1> must be clearly distinguished and controlled

100kBT = thermal noise limit

11


H. Takamizawa et al., Appl. Phys. Express 4, 036601 (2011)

“Laser-assisted atom probe tomography” (LAPT) picture

12

MOSFET


Moore’s Law = Miniaturisation

14

Gordon E. Moore Co-founder of Intel Corporation


Moore’s Law = Miniaturisation

15

Gordon E. Moore Co-founder of Intel Corporation


MOSFET

16



M. R. Castell et al., Nature Materials 2, 129 (2003)

20nm

20nm

5nm

“3D atom probe (3DAP)” picture

in ~2020


20nm device has only ~20 carriers.

MOSFET

switching energy nEd ~ 100kBT ( = 2.6 eV )

17



in ~2020

20nm

20nm

5nm

M. R. Castell et al., Nature Materials 2, 129 (2003)“3D atom probe (3DAP)” picture

Alternative of Si MOSFET is an urgent necessity.

!

But what can replace it?

18


Mott FET may be the only choice

First transistor (Bell Lab 1947)

Ge junction transistor (Bell Lab 1950)

Mott transistor (2020 ?)


Mott Insulator (nominally metal)Energy

Band InsulatorEnergy

What is the Mott transistor?


On State Off StateMott Transition

What is the Mott transistor?


On State Off StateMOSFET in 2020

20nm device has only ~20 carriers. Almost the end of the miniaturisation

20nm device has more than 100,000 carriers. Carrier density is independent of device sizes.

Mott FETVG

M. R. Castell et al., Nature Materials 2, 129 (2003)

“3D atom probe (3DAP)” picture

Basic concept of the Mott transistor

Mott insulators≈ ionic crystals (because of the strong electron correlations)

!

!

!

→ Defects form easily under large electric field.

26

Largest obstacle to realise the Mott FET


TiO2-x Co1-xO, Fe1-xO, Ni1-xO valence electron

1st electron ionisation

2nd electron ionisation

neutral composite

neutral composite

valence electron

Defects in transition-metal oxides


M. Janousch et al., Adv. Mat. 19, 2232 (2007)

0.2 mol% Cr-doped SrTiO3

By applying 0.1MV/cm for about 30 min

Pt

Pt

Vo are created, distributed in the channel, and form a metallic path.

VO creation by electric-field


Electrochemical reaction?

Science 339, 1402 (2013)

VO2VO2

30

Mott insulators ≈ ionic crystals (because of the strong electron correlations)

!

!

!

→ Defects form easily under large electric field.

Can we apply large electric field to Mott ins.

without creating oxygen defects?

31

Isao H. Inoue Neeraj Kumar Ai Kitou

Use Parylene to suppress

the defects formation

National Institute of Advanced Industrial Science & Technology (AIST) (Tsukuba, Japan)


"Biocompatible glass is coated with protective substances for anti-migration and insulating properties and this is where the Parylene C coating comes. !It also protects the microchip from natural substances in the body, that may penetrate through micro-cracks caused by mechanical damages."

From "moving a pet to Australia" website

by ParyleneProtect surface

Parylene coated rotors and stators are used to control the Canadian arm for NASA Space Shuttle.

Parylene coated circuit boards provides excellent resistance to moisture, chemicals, and mold. Circuit boards for medical equipment can be steam and gamma sterilised. Parylene can also prevent dendrite and tin whisker growth.

From "Paratronix Inc." website

Parylene coating of paper documents, autographs, and photos retards the aging process and protects from moisture, mold, and chemicals.

32


Creation of oxygen vacancies is suppressed. !Channel is kept clean.

P.-J. Chen et al., Lab on a Chip 6, 803 (2006)

conformal coating

by ParyleneProtect oxide surface

oxides

33


Parylene/SrTiO3 FET

Using Parylene for the gate insulator, mobility is drastically enhanced.

But carrier density is not large...

SrTiO3

34

35

High-k/Parylene bilayer to accumulate more carriers

35

High-k/Parylene bilayer to accumulate more carriers

must be very thin


"Biocompatible glass is coated with protective substances for anti-migration and insulating properties and this is where the Parylene C coating comes. !It also protects the microchip from natural substances in the body, that may penetrate through micro-cracks caused by mechanical damages."

From "moving a pet to Australia" website

In General, Parylene film is very thick

Parylene coated rotors and stators are used to control the Canadian arm for NASA Space Shuttle.

Parylene coated circuit boards provides excellent resistance to moisture, chemicals, and mold. Circuit boards for medical equipment can be steam and gamma sterilised. Parylene can also prevent dendrite and tin whisker growth.

From "Paratronix Inc." website

Parylene coating of paper documents, autographs, and photos retards the aging process and protects from moisture, mold, and chemicals.

Parylene film in most of the literatures are more than ~1µm thick.

36


High-k (HfO2, Ta2O5, etc.)/Parylene bilayer

Hybrid gate insulator ! high-k materials (~15 < ε < ~25) + Parylene-C (ε=3.2)

Isao Inoue and Hisashi Shima, Japan Patent Number: 5522688, Date of Patent: 18th April, 2014

37

https://dl.dropboxusercontent.com/u/51370691/Patents/JP_5522688%E7%89%B9%E8%A8%B1%E8%A8%BC.pdf


SrTiO3

AlHfO2

Au

Ti

parylene

BF-TEM image

38


SrTiO3

Al

HfO2

Ti

parylene

BF-TEM image

39

5nm


SrTiO3

Al

HfO2

Au Ti

parylene

STEM-EDS mapping

40

41

“Intel 4004 IC” the original microprocessor or “computer on a chip.”

We are preparing FET devices using a conventional

photolithography

Source Drain

Gate

V+V−

VH−

VH+

4µm12µm


~1014cm-2 and ~10 cm2/Vs

42

10

0.1

0.001

10k

1M

1G

h/e2

@300K

breakdown

@300K

L = 12µm W = 4µm

HfO2(20nm)/Parylene-C(8nm)/SrTiO3

<< 1nA

43

High-k/Parylene/SrTiO3

cleaner interface

continuous and large doping control

44

High-k/Parylene/Mott Insultor

cleaner interface

continuous and large doping control

Coming Soon!

45

What is the most suitable Mott insultor?

Not every M-I transtion is the Mott transition


ionic liquid [N,N-diethyl-N-(2-methoxyethyl)- N-methylammonium tetrafluoroborate DEME-BF4]

gatesource

drain10 µF/cm2 × 2 V = 1.25 × 1014 e / cm2

Mott FET -- ample carrier doping?

δ ∝VG

D(E

F) ∝

I SD

δC

Mott insulator Correlated Metal


Are these Mott transition?

10-2

10-3

10-4Cha

nnel

Res

istiv

ity (Ω

cm)

300220Temperature (K)

260

Nd0.5Sm0.5NiO3

VG = 0VVG = -2.5V

S. Asanuma et al., APL. 97, 142110 (2010)

VO2

10 2

10 6

Cha

nnel

Res

ista

nce

(Ω) 1010

300150 200 250100Temperature (K)

M. Nakano et al., Nature. 487, 459 (2012)


Phase diagram of strongly correlated electron systems

T/W

U/W

Correlated Metal Ordered State

(AF insulator, AF metal, SC., etc.)

Mott Insulator

=1/P or 1/δMott Transition is here


Phase diagram of strongly correlated electron systems

T/W

Correlated Metal

Ordered State (AF insulator, AF metal, SC., etc.)

Mott Insulator

VO2 NdNiO3

FE doping

Mott Transition is here No Mott

U/W =1/P or 1/δ


Real Mott transition

N. Takeshita, S. Takashima, C. Terakura, H. Nishikubo, S. Miyasaka, M. Nohara, Y. Tokura, and H. Takagi, arXiv:0704.0591.

Carlos Acha et al., unpublished.

GaTa4Se8NiS2

V2O3

H.R. Kokabi & F. Studer, Nucl. Instr. Meth. Phys. Res. B 124, 47 (1997)

InsulatorMetal

AFM


Phase diagram of Mott transitionT/

W

Correlated Metal


Mott Insulator

VO2 NdNiO3

No Mott

V2O3 NiS2 GaTa4Se8

real Mott

Mott FET!!

FE doping

U/W =1/P or 1/δ


Small E-field for real Mott transition?

P. Stoliar, L. Cario, E. Janod, B. Corraze, C. Guillot-Deudon, S. Salmon-Bourmand, V. Guiot, J. Tranchant, M. J. Rozenberg, Adv. Mat. 25, 3222 (2013).


Coexistence region is there!T/

W

Correlated Metal


Coexistance Region

Mott Insulator

VO2 NdNiO3

No Mott

V2O3 NiS2 GaTa4Se8

real Mott

Mott FET!!

FE doping

U/W =1/P or 1/δ


Phase separation / filamentation in real Mott transition

M. Eckstein, M. Kollar, M. Potthoff, D. Vollhardt, PRB 75, 125103 (2007).

Phas

e Sep

arat

ion!

Phas

e Sep

arat

ion!

P. Stoliar, L. Cario, E. Janod, B. Corraze, C. Guillot-Deudon, S. Salmon-Bourmand, V. Guiot, J. Tranchant, and M. J. Rozenberg, Adv. Mat. 25, 3222 (2013).

55

1. Why we need the Mott transistor? —- miniaturisation limit!

3. Feasible Mott FET —- real Mott transition & filamentation

Summary

2. How to avoid defects formation at the interface —- Parylene!

57



Mott transistor Exotic phonomena ✔on the horizon!

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Mott transistor Exotic phonomena ✔on the horizon!

Several more

slides to show

if time allows

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National Institute of Advanced Industrial Science & Technology (AIST) (Japan)

Christos Panagopoulos

Nanyang Technological University (Singapore)

Azar B. Eyvazov*

Isao H. Inoue

CNRS & Université Paris Sud (France)

Pablo Stoliar** Marcelo J. Rozenberg***

*also AIST (now a PhD student in Cornell University, US)

**also Universidad Nacional de San Martin, Argentina, and Université de Nantes, France

***also Universidad de Buenos Aires, Argentina


Unusual I-V curves

Hardly seen in Al2O3/SrTiO3 Al2O3/SrTiO3 has some amount of carriers from the first

K. Ueno et al., App. Phys. Lett. 83, 1755 (2003)

10-6

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A. B. Eyvazov et al., Sci. Rep. 3, 1721 (2013)


Schematic picture of channel

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A. B. Eyvazov et al., Sci. Rep. 3, 1721 (2013)

Spatio-temporal current paths. All disappears when VG turns off. Not due to oxygen defects!!

High-k/Parylene/SrTiO3 FET

cleaner interface

filamentation62


1011 1012

H. Nakamura et al., Appl. Phys. Lett. 89, 133504 (2006)

h/e2=25.8kΩ

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Filamentation at 7K

7K

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1011 1012

Domain formation of doped carrier and percolation transition

h/e2=25.8kΩ

1011 1012 1013

108

106

104

102

1


Another “Zero-R” State

20mK

7K

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1011 1012


h/e2=25.8kΩ

1011 1012 1013

108

106

104

102

1

Gate-annealed superconductivity below 350mK


due to oxygen defects!!


20mK

7K

39

1011 1012


h/e2=25.8kΩ

1011 1012 1013

108

106

104

102

1

Gate-annealed superconductivity below 350mK


Spatio-temporal current paths. All disappears when VG turns off. Not due to oxygen defects!!

due to oxygen defects!!


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oxygen vacancies due to VG application hinder this fragile “zero-R” state.

Sample B

the first few applications of VG

only seen during


VG (V)

continuous & reversible control of normal ↔ ”zero-R”

transition!

TC? ~ 120mK HC2? ~ 0.01T JC ? ~ 0.1µA/cm

TC ~ 400mK HC2 ~ 0.1T JC ~ 300µA/cm

·SC at electrolyte/SrTiO3 interface ·gate-annealed SC ·SC at LaAlO3/SrTiO3 interface ·bulk superconductivity

is Fragile

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“Zero-R State”

Feasible Mott FET: Concept, Obstacle, and Future

Science

Transcript of Feasible Mott FET: Concept, Obstacle, and Future