Graphene and Hexa Boron Nitride Heterostacks and Beyond

Philip Kim

Physics Department, Columbia University

Beginning of Graphene Research

Geim & Novoselov

Submitted 19 July 2004; accepted 15 September 2004

2010 Physics

Various 2D van der Waals Systems

X

X

M

C

BN

graphene

hexa-BN

Metal-Chalcogenide

M = Ta, Nb, Fe, Co, Mo, …

X = S, Se, Te, …

Bi2Sr2CaCu2O8-x

Charge Transfer Bechgaard Salt

(TMTSF)2PF6

Lead Halide Layered Organic

Semiconducting materials: WSe2, NbS2, MoS2, … Complex-metallic compounds : TaSe2, TaS2, … Magnetic materials: FeSe2, CoSe2 ,…Superconducting: NbSe2, Bi2Sr2CaCu2O8-x, ZrNCl,…

Boron Nitridegraphene

Band Gap Dielectric Constant Optical Phonon Energy Structure

BN 5.5 eV ~4 >150 meV Layered crystal

SiO2 8.9 eV 3.9 59 meV Amorphous

Comparison of h-BN and SiO2

hexa-Boron Nitride: Ideal Dielectric

Co-lamination and Transfer Techniques

1. spin coat substrate with PMMA and scratch onto top surface

2. Lift off PMMA; graphene comes with it!

3. Align graphene over target using a micro-manipulator. PMMA is brought into contact with target and annealed.

Dean et al. Nature Nano (2010)

Flat Graphene on hBN

BNgraphene

0.5 um

Roughness

-0.4 -0.2 0.0 0.2 0.40.0

0.4

0.8

1.2

Graphene BN

frequ

ency

[a.u

.]

height [nm]

0.22 nm

2 um

Room temperature mobility >100,000 cm2V-1s-1

Extremely High Mobility in Graphene/BN

Graphene Integer and Fractional Quantum Hall Effect

5 m

Dean et al. Nature Phys (2011)Young et al., Nature Phys (2012)

0 1 0 2 0 3 0-5 0

0

5 0

1 0 0

1 5 0

3 4 5

(K

)

B (T )

Broken Sym Integer QHE Gaps FQHE Gaps

4/3 ~ 50K

* Spontaneous broken SU(4) symmetrydue to many body correlation

* Energy Scale is big

4 ~ 200 K

Gap Opening in Bilayer Graphene

Expt: K.F. Mak et al (Columbia group), Also: Feng Wang group (UC Berkeley)

Optical Spectroscopy Transport Measurement

Taychatanapat and Jarillo-Herrero, Phys. Rev. Lett (2010)K. Zou and J. Zhu, Phys. Rev. B 82, 081407(R) (2010)

>200 meV transport gaps may be possible!

-2 0 20.0

5.0x104

1.0x105

1.5x105

2.0x105

2.5x105

3.0x105

BG = -50 V -40 V -30 V -20 V -10 V 0 V 10 V 20 V 30 V 40 V 50 V

Rxx

(Ohm

s)

VTG (Volts)

4-terminalvoltage bias

0 1 2 3

0

20

40

60

80

100

120

2-Terminal ConductanceVBG = -60 Volts

Ixx

(nA)

Vgate (Volts)

BN top and bottom gate

Gap Opening in Bilayer Graphene / hBN

T =1.7 K

Wang et al. (Hone, Kim, Shepard) (2012)

BN/Graphene/BN/Graphene/BN

Kim, Tutuc, PRB (2011); Tse, Das Sarma PRB (2007)

0 5 10 15 20 25-10

-5

0

5

10

RD

rag (

Ohm

s)

VBG (Volts)

224.91 K 201.96 K 175.15 K 148.37 K 98.53 K 75.48 K 48.54 K 25.23 K 11.26 K

I+ VDrag

I-Coulomb Drag Configuration

grnd

0 5 10 15 20 25

63

50

38

25

13

0

row

50 100 150 200 250

-5

0

5

5 V 10 V 11.5 V 18.5 V 20 V 25 V

RD

rag (

Ohm

s)

Temperature (K)

BN tunneling junction/ Drag DeviceDean et al. (Hone, Kim, Shepard) (2011)

Maher et al. (2012)

Controlling Spin and Pseudo Spin in Bilayer

5 m

Si

SiO2

BNBilayer graphene

BNCr/Au

Doubly gated Bilayer graphene with BN dielectric

Electric field: controlling pseudo spin

Parallel magnetic field: controlling spin

Conductance

Metal to Insulator Transition

Previous work: Weitz et al (2010)

Conductance ()

Magnetic Field:Control Orbitals

E-field induced insulator

B-field induced insulator

E-field induced insulator

Assembly of Various 2D Systems

X

X

M

C

BN

graphene

hexa-BN

Metal-Chalcogenide

M = Ta, Nb, Fe, Co, Mo, …

X = S, Se, Te, …

Bi2Sr2CaCu2O8-x

Charge Transfer Bechgaard Salt

(TMTSF)2PF6

Lead Halide Layered Organic

Semiconducting materials: WSe2, NbS2, MoS2, … Complex-metallic compounds : TaSe2, TaS2, … Magnetic materials: FeSe2, CoSe2 ,…Superconducting: NbSe2, Bi2Sr2CaCu2O8-x, ZrNCl,… A

BA

CA

Yang et al. Science in press (2012)

Graphene/Silicon hybrid Device: Graphene Barristors

Gate Variable Schottky Diode

Invertor and half adder is demonstrated!

Layered Semiconductor: MoS2

Band Gap ~ 1. 8 eVMobility ~ 200 cm2/Vsec

Radisavljevic et al., Nature Nano (2011)

Choi et al. in preparation (2012)

Controlled Charge Trapping by Ultrathin MoS2 Layers in Graphene/hBN/MoS2 Heterostructured Memory Devices

Floating MoS2 Gate

Hysteresis due to Controlled Charge Trapping

Memory Device Operation

SummaryGraphene on hBN Bilayer gapped device Double layer Coulomb drag

Controlled Charge TrapEmploying MoS2 Layer

Metal/Insulator Transition

Graphene/ NbSe2Tunable Graphene/Si Schottky Diode

Acknowledgement

Funding:

Past MembersMelinda Han (Ph.D. 2010, Frontier of Science Fellow, Columbia University)Meninder S. Purewal (Ph.D. 2008)Josh Small (Ph.D. 2006)Yuanbo Zhang (Ph.D. 2006, Professor, Fundan University)Yuri Zuev (Ph.D. 2011, IBM Fishkill)Kirill Bolotin (Assistant Professor, Department of Physics, Vanderbilt University)Byung Hee Hong (Associate Professor, Department of Chemistry, Seoul National University) Pablo Jarillo-Herrero (Assistant Professor, Department of Physics, MIT)Keunsoo Kim (Assistant Professor, Department of Physics, Sejong University)Namdong Kim (Research Scientist, POSTECH)Barbaros Oezyilmaz (Assistant Professor, Department of Physics, National University of Singapore)

Current MembersYue ZhaoMitsuhide TakekoshiAndrea YoungDmitri EfetovFereshte GhahariPatrick MaherYoung-Jun Yu (jointly with GRL, POSTECH)Vikram Deshpande (jointly with Hone group)Paul Cadden-Zimansky (Columbia Frontier of Science Fellow)Chenguang Lu (jointly with Hone and Herman

Collaborating Students/postodcsCory Dean, Inanc Meric, Lei Wang, Sebastian Sorgenfrei, Kevin Knox, Nayung Jung, Seok Ju Kang, Jun Yan, Yanwen Tan, Kevin Knox

CollaboratorsHorst Stormer, Aron Pinczuk, Tony Heinz, Abhay Pasupathy, Latha VenkataramanLouis Brus, George Flynn, Colin Nuckolls, Jim Hone, Ken Shepard, Louis Campos, Rick OsgoodT. Taniguchi, K, WatanabeAndre Geim, Kostya Novoselov, Sanka Das Sarma

Kim group and friends (2011)