Diapositive 1

Report
Graphene adhesion under
high pressure
Alfonso San Miguel
J. Nicolle, D. Machon,
Ph. Poncharal, O. Pierre-Louis
Laboratoire de Physique de la Matière Condensée et Nanostructures
Université de Lyon 1 et CNRS
Probing graphene adhesion
Measure of
graphene adhesion energy
Adhesion energy :
0.45 ± 0.02 J m−2 for monolayer graphene
0.31 ± 0.03 J m−2 for samples containing two to five graphene sheets
S.P. Koenig et al, Nature Nanotechnology 6, 543–546 (2011)
Graphene under high pressure
J. Nicolle, D. Machon, P. Poncharal,
O. Pierre-Louis and A. San Miguel
Nano Letters 11, 3564 (2011)
Graphene Raman signal
Raman of a single layer sample
6000
5500
2D
5000
Intensity (a.u)
4500
G
4000
3500
3000
2500
D
2000
1500
1000
500
0
1200
1400
1600
1800
2400
-1
Raman shift (cm )
2600
2800
Experimental : Raman in DAC
G
2D
-1
-1
R am an shift (cm )
(a)1400
1600
2600
Raman shift (cm )
2800
1600
(i)
G
λ =647.1 nm
1400
2600
2800
G
(i)
(i)
2D
(i)
(X5)
2D
(X5)
P=7.0 GPa
P=3.5 GPa
(i)
(i)
(i)
G
G
(i)
2D
(X2)
(X2)
2D
P=5.0 GPa
P=2.4 GPa
(i)
(i)
(i)
2D
G
(i)
2D
(X2)
G
(X2)
P=1.0 GPa
P=2.4 GPa
2D
G
2D
G
Ambient Pressure
Ambient Pressure
14 00
1 600
2 600
280 0
-1
R am an sh ift (cm )
1400
1600
2600
2800
-1
R a m a n s h ift (c m )
Bilayer
Graphene
(b)
G-band position with pressure
(PTM: 4:1 methanol ethanol)
G-band pressure slope
Graphene Raman G-band in hydrostatic conditions
Hooke law for an hexagonal system:
  xx   S11

 
  yy   S12
  S
 zz    13
  yz  
  
 zx  
  
 xy  
S12
S11
S13
S13
S13
S33
In-plane Biaxial deformation: (z = 0)
 2 D  2.S11  S12 .
In-plane Triaxial deformation: (z = )
 3D  2.S11  S12  S13 .
S 44
S 44
  
 
  
  
 z 
 0 
 
 0 
2S11  S12  0 
G
 7.5cm 1.GPa 1
P
G
 4.0cm 1.GPa 1
P
but why so … ?
BIAXIAL
TRIAXIAL
What can be expected ?
Substrat (Si+300 nm SiO2)
can the substrate tract
(at least partially) graphene ?
AFM: High-Fidelity Conformation of Graphene
to SiO2 Topographic Features (99%)
Graphene on SiO2
SiO2 substrate
rms ~ 0.35 nm
W.G. Cullen et al., PRL 105, 215504 (2010)
Adhesion of a membrane on
a sinusoidal surface
Unbinding
Perfect adhesion
O. Pierre-Louis, Phys. Rev. E 78,
021603 (2008)
A very familiar phenomena
Unbinding between n=2 and 3
3.0
2.5

2.0
1.5
1.0
Calculated
unbinding transition
0.5
0.0
1
2
 =(keq/kg)2
kg : typical substrate curvature
keq=(2gn/Cn)1/2 is the adhesion equilibrium curvature
3
4
5
6
Number of layers (n)
gn : multilayer graphene adhesion energy on SiO2
Cn : bending rigidity.
BIAXIAL
TRIAXIAL
Why this difference of
~ 3 – 3.5 cm-1 GPa-1 ???
BIAXIAL
TRIAXIAL
Splitting of the bilayer 2D band:
an indication of doping
160
Alcohol
Argon
-1
-1
140
120
120
100
100
80
80
60
0
0
1
2
3
2D1A
2D1A
2D2A
2D2B
2D2A
20
2D2B
0
4
0
1
2
3
40
4
Pressure (GPa)
Predicted by: C. Attaccalite et al., Nano Letters 2010, 10, 1172-1176.
-1
20
Argon
2D1B
-1
40
60
Alcohol
2D1B
2D(P)-2D(0) (cm .GPa )
2D(P)-2D(0) (cm .GPa )
140
160
I(2D)/I(G) evolution
I(2D)/I(G)
1,5
1 layer
2 layers
Argon
1,0
0,5
0,0
0
1
2
3
4
5
6
Pressure (GPa)
7
8
I(2D)/I(G) evolution
1,5
1 layer
2 layers
1 layer
2 layers
Argon
I(2D)/I(G)
Alcool
1,0
0,5
0,0
0
1
2
3
4
5
6
Pressure (GPa)
7
8
High pressure induced doping
Pressure
effect
A. Das et al., Nat Nano 2008, 3, 210-215.
High pressure induced doping
n ~ 5 x1013 cm-2 at 7 GPa
(EF ~ 1 eV)
n/ P
n
1
2
PTM
(x1013)
alc.
Ar
alc.
Ar
N2
(cm-2 GPa-1)
0.70.2
0.2 0.2
0.80.2
0.1 0.2
0.1 0.2
Doping effect on the G-band
G
cm1
 3.6
P
GPa
( graphene)
Pressure
effect
G
cm1
 3.4
P
GPa
(bilayer)
Graphene : A. Das et al., Nat Nano 2008, 3, 210-215.
Bilayer: A. Das et al., Phys. Rev. B 79, 155417 2009
A last question : why no-doping for n=3 in alcohol ?
Substrate mediated doping !
Substrate mediated doping
by silanol groups
Si–O–Si + Alcohol → Si–O–H
Si–O–H groups as e- donors
Lee et al. J. Phys. Chem. C Lett. 111, 12504 (2007)
Conclusions
• Adhesion or unbinding decides on the
graphene pressure behavior (2D vs 3D)
• Adhesion/unbinding transition observed
between n=2 and n=3 (n =2 is different !!)
• Extreme surface P-mediated doping in alcohol
in the adhesive configuration
Applications: pressure/stress sensors
Doping and mechanical (bi-axial, n=1,2)
pressure effects
n
PTM
n/ P
[G/ P]dop
G/ P
[G/ P]mech
(x1013)
(cm-1 GPa-1)
(measured)
(cm-1 GPa-1)
(cm-2 GPa-1)
1
2
(cm-1 GPa-1)
alc.
0.70.2
3.61.1
10.50.2
6.91.4
Ar
0.2 0.2
1.0 1.1
7.6±1.0
6.6 2.0
alc.
0.80.2
3.41.1
10.40.3
7.01.4
Ar
0.1 0.2
0.3 0.6
6.9±1.0
6.6 1.6
N2
0.1 0.2
0.3 0.6
6.9±0.2
6.6 0.8
2D band:
Identification of the number of layers
(b) l=647.1 nm
(a) l=514 nm
HOPG
HOPG
n=5
n=5
n=4
n=4
n=3
n=3
n=2
n=2
n=1
n=1
2550
2650
2750
2550
2650
2750

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