Supplemental Material
Doping efficiency of single and randomly stacked bilayer graphene by iodine adsorption
HoKwon Kim (김호권)1, Olivier Renault1, Anastasia Tyurnina2, Jean-Pierre Simonato2, Denis
Rouchon1, Denis Mariolle1, Nicolas Chevalier1, and Jean Dijon2
1
Univ. Grenoble Alpes, F-38000 Grenoble, France
CEA, LETI, MINATEC Campus, F-38054 Grenoble, France
2
Univ. Grenoble Alpes, F-38000 Grenoble, France
CEA, LITEN, Minatec Campus, F-38054 Grenoble, France
Experimental Details
Low temperature chemical vapor deposition (CVD) growth of graphene on a thin platinum (Pt)
film was performed in a custom made CVD reactor to prepare the graphene film with a small
grain size distribution for the doping experiments. The specific CVD chamber allowed us to
perform the graphene deposition at the substrate temperature not higher than 700° C with a
control over the quality of as-synthesized graphene, its grain size, and density of possible
defects. Afterward, graphene was transferred onto SiO2 (100 nm thick)/Si(100) substrate
through electrochemical delamination with a spin-coated poly(methyl methacrylate) (PMMA)
support and Ti (5 nm)/Au(50 nm) electrodes were fabricated on top of the transferred
graphene through photolithography and e-beam deposition of the electrodes followed by liftoff. Electrodes of circular shape (Fig. 1a) were designed with varying channel lengths in order
to carry out conductivity measurements by the two-probe station.
Io order to dope graphene films with iodine, the samples were placed for 3 days at the center
of an enclosed glass vial saturated with iodine vapor produced from heated iodine powder
located at the base of the vial below the sample. The heating of the entire vial was maintained
by immersion in oil bath at a temperature of 100 °C.
1
(b)
(a)
1L
2L
counts
I doped
without doping
counts
I doped
without doping
1200
1400
1600
2400
2600
2800
1200
1400
1600
wavenumber (cm-1)
2400
2600
2800
wavenumber (cm-1)
Fig. S1 Raman spectra of graphene 1L (a) and 2L (b) areas. Excitation laser wavelength of 514 nm was used.
Z
X Range: 12.5 µm
FM-KFM
2L
1L
\
X Range: 25 µm
[nm]
CPD
-572 mV
-563 mV
[µm]
Fig. S2. Frequency modulated KFM measurements on 1L, folded 2L graphene on SiO2 illustrating surface
topography, height profile and contact potential difference (CPD) related to the work function for 1L and 2L
graphene. According to the CPD mapping, 1L and 2L graphene exhibit almost identical values with a difference
close to the resolution limit (~ 10 mV).
ptcr1362si. 1
ptcr1362si. 1
x 10 2
(b)
Au 4f
25
O 1s
14
12
1000
800
600
400
Binding Energy (eV)
200
6
4
I 3d3/2
I 3d5/2
Au 4p 3/2
8
Au 4s
Counts
0
Si 2s
Si 2p
O 2s
5
C 1s
I 3d3/2
I 3d5/2
10
O KLM
Counts
10
15
C 1s
20
Au 4d3/2
Au 4d5/2
(a)
x 10 2
2
0
1000
800
600
400
200
Binding Energy (eV)
Fig. S3. XPS survey spectra of SiO2 substrate (a) and Au electrode (b) regions.
2
Before Annealing
36000
28000
24000
32000
4.18eV
4.61eV
28000
Frequency
20000
Frequency
After Annealing at 150 °C
(b)
(a)
16000
12000
8000
4000
24000
20000
16000
12000
8000
4000
0
0
4.0
4.1
4.2
4.3
4.4
4.3
4.4
Work function (eV)
(c)
45
40
Name
X=-774um, Y=1048um; CA=1500 um; EA1=2 mm
X=-774um, Y=1048um; CA=1500 um; EA1=2 mm
C1s
Pos.
284.6361
285.3542
FWHM
0.8392
1.9578
Area
29.758
14.997
4.5
4.6
4.7
4.8
Work function (eV)
%Area
66.49
33.51
(d)
95
Name
X=-774um, Y=1048um; CA=1500 um; EA1=2 mm
X=-774um, Y=1048um; CA=1500 um; EA1=2 mm
C1s
90
Pos.
284.7797
285.4400
FWHM
0.8481
1.4017
Area
27.993
5.122
%Area
84.53
15.47
85
35
80
CPS
CPS
30
25
75
20
70
15
65
10
60
5
290
55
289
288
287
286
285
Binding Energy (eV)
284
283
289
288
287
286
285
284
283
282
Binding Energy (eV)
Fig. S4. Work function distribution histogram and C 1s spectra of as-transferred graphene before (a,c) and after
annealing (b,d).
3