Lecture 13 Graphene Properties

7/25/2019 Lecture 13 Graphene Properties

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Graphene

Single atomic layer of graphite

Castro-Neto, et al.Rev. Mod. Phys. 81

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I. Graphene Electronic Properties(isolated graphene sheets)

II.Graphene Formation—Growth on SiC

III.Graphene Growth on BN, Co!", etc.



Castro-Neto, et al.Rev. Mod. Phys. 81

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CastroNeto

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'raphenes )and str*ct*reyields *n*s*al properties

%+ective mass (m# d%/d0-1

Most semicond*ctors, !.1 m! 2 m 2 1 me

'raphene, m 2 !.!1 m! (depending on n*m)erof carriers# 3herefore, e4pect 5%R6 high mo)ility in graphene

3he velocity of anelectron at the &ermilevel (v&#s inversely related tome+

9



Castro-Neto, et al. Rev. Mod.Phys. 81 (!!"# 1!"%+ective mass for graphene does

get very small as n 1!1

:



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<. =>? 'raphene is great, lots of interestingproperties for devices@

7. AoB do yo* ma0e a device

<. 6o* need a sheet of graphene@

7. =>, hoB do yo* get a sheet of graphene

<. A=P', scotch tape, and tBeeDers@

7. @EFGHH

#he Big Pro$lem with graphene% an

imagined con&ersation%

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AoB do yo* JgroBK graphene

6o* can evaporate Si from SiC(!!!1# (either face#Pop*lariDed )y the de Aeer gro*p at 'eorgia 3ech.

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Can groB m*ltilayer Llms of graphene on SiC(aDim*thally rotated from each otherelectronically deco*pled@#

SiC

nterfacial layer

(anneal at 11:! C#

<nneal at 1$:! C

<*ger, graphene groBth on SiC, deAeer etal.

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<ngle resolved PS (%mtsev, et al, PR7II(!!8# 1::$!$# shoBs transition to

graphene )and str*ct*re

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<dQacent layers on graphene /SiC are deco*pled fromeach other,O*e to aDim*thal rotation

1



M7

'raphene on SiC(!!!1# Not *niform on an atomic level,di+erent regions d*e to di+erent Fs of layers, orientations

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'raphene/SiC photoemission? varying hv can varythe sampling depth (%mtsev, et al, PR7 II (!!8#

1::$!$

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3he covalently )o*nd stretched graphene (CS'model#%mtsev, et al., PR7 II (!!8# 1::$!$

1:



Pertinent *estions? AoB do <dQacent 'raphene Sheets co*pleelectronically

Single layer 'raphene (good#

Many layer'raphite (meh@#

<nsBer? =n SiC, <dQacent Sheets apparently not co*pled d*eto aDim*thal rotation

hen/hoB this transitionocc*rs is very pertinent todevices

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Core (let) and &alence $and(right) PES graphene growthon SiC (Emtse&, et al)

%4plain the implications of this for graphene co*pling

)etBeen layers

1I

+ i i

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+oti&ation% irect Growth on ielectric S*$strates%

#oward Ind*striall- Practical, Scala$le Graphene—Basede&ices

Graphene Growth% Con&entionalpproaches

Metal or A=P'

C/ graphene monola-er

Si!0Si

transfer

1es*lt% graphenemonola-er, interacial inhomogen

SiC(!!!1#

T 1:!! >

SiC(!!!1#

1es*lt% graphenemonola-er or m*ltila-eronSiC(2223)

Si evaporation

!*r Foc*s%irect C/,P/ or +BE

!n

ielectrics

graphene

Si(322)

+g!(333)

n#opGate

FE#% Band gap

Coherent4SpinFE#%

Spintronics

Charge-)ased devices

+*lti4*nctional,non4&olatilede&ices

18

graphene

Co!"(3

33)

Co(333 ) or

S i(322 )4

ga te





irect Growth o Graphene on ielectric S*$strates% S*mmar-

1"

Gate

N7 7*tterUy





*ger

5EE I(/)

S#+

Intro6transer

deposition

Gate&al&es BCl

N7

#*r$o

7*tterUyvalve

Sample heating

to 1000 K @ 1Torr

87/ cham$er, 324

33 #orr

+BE

LEED

Hemispheri

cal analyzer

(XPS)

Sample processing P = 10-9

-10-3 orr!H" #nalysis

$ham%er

P & ' 1 0-10 orr

Freeradicalso*rce

5 orP/

Sample Introcham$er P 932

#orr :324;

Graphene6Co!"

Graphene6+g!(33

Graphene growth<

characteri=ation !




'raphene/7N/R*(!!!1#? 7Qel0evig, et al

%%O shoBs 7N and 'raphene N=3 aDim*thally rotated@

!r$italh-$ridi=ation with1* d?

1



'r/7N/R*(!!!1#? nverse photoemission. V not o)served@

7N layer does N=3 screen graphene from or)italhy)ridiDation and charge transfer from R*@

Graphene on Co ! (333)% +olec*lar Beam




Graphene on Co!"(333)% +olec*lar Beam

Epita>-S*$strate Preparation

E&aporato

r P@ 324A #orr

Sapphire(2223)

2 D

Sapphire(2223)

Co(333) dissol&ed!

Sapphire(2223

)

Co(333)

3222 D687/

@ +5Co!"(333)

! segregation

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Graphene growth onCo!"(333)6Co(2223)

+BE (graphite so*rce)3222 D%5a-er4$-4la-er growth

9

1st M

nd M

2."+5

+5

M. Zhou, et al., J. Phys.: Cond. Matt. ! "01# 0$01

5EE%





5EE%!>ide6Car$onInterace isincommens*rate%

ierent thangraphene onSiC or BN?

%raphene&omain Si'ed

"(rom )*+M#1-00 "/omp. to+P%#

400 300 200 100 05000

10000

15000

20000

25000

30000

35000

40000

O1

O2

G2

I

n t e n s i t y

Pixel Position

G1

400 300 200 100 05000

10000

15000

20000

25000

30000

35000

40000

I n t e n s i t y

Pixel Position

O1

O2

G2

G1

=4ide spotsatten*atedBithincreasingCar)oncoverage

.8 W =-= s*rface repeatdistance on Co$=9(111#W. Meyer, et al. JPCM 0 (2008) 265011

.8W

.:W

2."+5

+5

graphene

Co!"(333)

:

;: e5 )eam energy

M. Zhou, et al., J. Phys.: Cond. Matt. !"01# 0$01

HPS% C(3s) Shows ' s-stem%




HPS (separate cham$er)%

0A".(J2.3) e/$indingenerg-%Interacial

polari=ation6charge transerto o>ide

No C4! $ondormation

;

'K'

HPS% C(3s) Shows ' s-stem%Binding Energ- indicatesgraphene

o>ide chargetranser

l DL

so*rce

M. Zhou, et al., J. Phys.:Cond. Matt. ! "01#

chargen4t-pe

irectl- grown



E

chargetranser

For$ea*>, et

al.

n t-pep4t-peirectl- grown

graphene6metals anddielectrics%

In&erse photoemission andcharge transer

Position of σ (relative to %&#indicates direction of interfacialcharge transfer(>ong, et al., X.Phys. Chem. C.119 (!1!# 1;18

M*ltilayers

I



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Generali=ation, irectl- Grown Graphene andCharge #ranser% !>ides (p4t-pe) &s. +etals (n4

t-pe)

3ransition

metals(R*, Ni, C*, rY#

n4t-peM metal tographene charge

transer

=4ides, SiC

p4t-peM

graphene tos*$stratecharge transer

%&

%&

graphene

graphene

e4

e4



S*spendedgraphene

'raphene (feB layer# onCo$=9?

M*ch more cond*ctive thans*speneded graphene

hy•SigniLcant doping•Aigh mo)ility (AoB

high# "



Concl*sion%

Graphene%

5arge area growth onpractical s*$strates

critical or de&icede&elopment.

Interactions with

s*$strates and (ma-$e)other graphene la-ers arecritical to de&ice

properties $!

Lecture 13 Graphene Properties

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