Supporting Information:
Plasmon-enhanced ultraviolet photoluminescence from graphenes on
ZnO films
Sung Won Hwang,1 Dong Hee Shin,1 Chang Oh Kim,1 Seung Hui Hong,1 Min Choul
Kim,1 Jungkil Kim,1 Keun Yong Lim,1 Sung Kim,1 Suk-Ho Choi,1,* Kwang Jun Ahn,2
Gunn Kim,3 Sung Hyun Sim,4 & Byung Hee Hong4
1
Department of Applied Physics, College of Applied Science, Kyung Hee University,
Yongin 446-701, Korea. 2School of Physics and Astronomy, Seoul National University,
Seoul 151-747, Korea. 3Department of Physics, Kyung Hee University, Seoul 130-701,
Korea. 4Department of Chemistry, SKKU Advanced Institute of Nanotechnology,
Sungkyunkwan University, Suwon 440-746, Korea.
Contents
Figure S1 AFM image and depth profiles of graphenes.
Figure S2 Raman spectra of graphenes.
Figure S3 Optical microscopy image and corresponding micro-PL mapping image of
another HOPG-derived graphenes/ZnO hybrid structure
Figure S4 AFM surface images of ZnO films.
Figure S5 SEM surface images of ZnO films.
Figure S6 Optical microscopy images and corresponding micro-PL mapping images of
CVD-grown graphenes/ZnO hybrid structures.
Figure S7 PL spectra for the hybrid structures used in Fig. S6.
Figure S8 Micro-PL spectra for the hybrid structures used in Fig. S6.
1. AFM image and depth profiles of graphenes
The AFM height profiles of typical HOPG-derived graphenes on a ZnO film identified
steps between graphenes and between graphene and the ZnO film. The heights for each
step were about 0.35 and 0.8 nm, respectively. It has been reported that the AFM step
height of a SG on SiO2 varies between 0.5 and 1 nm and the apparent thickness of a SG
is 0.35 nm [1-3].This indicates that the graphene flakes on a ZnO film are well
characterized also by the AFM height profiles.
Figure S1. (a) AFM topographic image of typical graphene flakes on a ZnO film. (b)
Depth profile along the red line in Fig. 1(a). (c) Depth profile along the blue line in Fig.
1(a). The ZnO film was annealed at 900 oC.
2. Raman spectra of graphenes
We obtained Raman spectra for the graphene layers on ZnO film and compared them
with previous ones [3-5]. Two distinctive features in the Raman spectra were the G peak
at 1580 cm-1 and the 2D peak at 2700 cm-1. The most prominent difference in the
spectra of SG, FGs, and HOPG lay in the 2D peak, but the 2D peaks of FGs with the
number of layers n  5 was hardly distinguishable from that of HOPG. The peak
position of SG was at 2683 cm-1, exactly same with that reported in Ref. [4]. The shape
and the peak position of HOPG coincided with those in Ref. [2-4] as well. The
Lorentzian lines to best fit the 2D peaks of the FGs were compared with those in the
previous reports [3,4] to distinguish among FGs with different numbers of layers (n = 2,
3, and n  5).
Figure S2. Raman spectra of graphenes with n = 1, 2, 3, and n  5 on ZnO films and
HOPG. a.u.- arbitrary units. The data were collected using 514.5 nm radiation under
ambient conditions. The ZnO films were annealed at 900 oC.
3. Optical microscopy image and corresponding micro-PL mapping image of
another HOPG-derived graphenes/ZnO hybrid structure
Figure S3. Optical microscopy images showing the graphene regions that are separated
from the bare region on the surface of ZnO film for another typical hybrid structure of
HOPG-derived graphenes/ZnO films and corresponding micro-PL mapping image. The
ZnO films were annealed at 900 oC.
4. AFM and SEM surface images of ZnO films depending annealing
temperature
Figure S4. AFM surface images of ZnO films for various annealing temperatures.
Figure S5. SEM surface images of ZnO films for various annealing temperatures.
5. Optical microscopy images and corresponding micro-PL mapping images
of CVD-grown graphenes/ZnO hybrid structures
Figure S6. Optical microscopy images showing CVD-grown graphene regions (B) that
are separated from the bare region (A) on the surface of ZnO film for hybrid structures
with few-layer graphenes with (a) n =12, (b) n =35, and (c) n > 5, and corresponding
micro-PL mapping images.
6. PL and micro-PL spectra for the hybrid structures used in Fig. S6
Figure S7. PL spectra for the 3 types of hybrid structures used in Fig. S6. The inset
shows the PL intensity as a function of layer number. The PL intensity decreases with
the increasing number of graphene layers, indicating that only PL blocking effect by the
graphenes exists without the plasmon-mediated effect.
Figure S8. Micro-PL spectra for the 3 types of hybrid structures used in Fig. S6. The
inset shows the micro-PL intensity as a function of layer number.
References
[1] K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V.
Grigorieva, S. V. Dubonos, A. A. Firsov, Nature 438, 197 (2005).
[2] U. Stöberl, U. Wurstbauer, W. Wegscheider, D. Weiss, J. Eroms, Appl. Phys. Lett. 93,
051906 (2008).
[3] A. Gupta, G. Chen, P. Joshi, S. Tadigadapa, P. C. Eklund, Nano Lett. 6, 2667 (2006).
[4] A. C. Ferrari, J. C. Meyer, V. Scardaci, C. Casiraghi, M. Lazzeri, F. Mauri, S.
Piscanec, D. Jiang, K. S. Novoselov, S. Roth, A. K. Geim, Phys. Rev. Lett. 97, 187401
(2006).
[5] D. Graf, F. Molitor, K. Ensslin, C. Stampfer, A. Jungen, C. Hierold, L. Wirtz, Nano
Lett. 7, 238 (2007).