Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Focused Session: Epitaxial Graphene I
O 8.5: Vortrag
Montag, 23. März 2009, 12:30–12:45, SCH 251
Raman Spectra of Epitaxial Graphene on SiC and of Epitaxial Graphene Transferred to SiO2 — Dong Su Lee, •Christian Riedl, Benjamin Krauss, Klaus von Klitzing, Ulrich Starke, and Jurgen H. Smet — Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart
Raman spectra were measured for epitaxial graphene grown on SiC and compared to those obtained for epitaxial graphene successfully transferred from SiC to SiO2 [1]. The number of layers for graphene on SiC(0001) was preassigned by angle-resolved ultraviolet photoemission spectroscopy (ARUPS) [2]. The Raman spectra of epitaxial graphene show significant differences as compared to micromechanically cleaved graphene obtained from highly oriented pyrolytic graphite crystals. The G peak is found to be blue-shifted, presumably due to charge doping from the substrate. The 2D peak does not exhibit any obvious shoulder structures, but it is much broader and almost resembles a single-peak even for multilayers. However, the linewidth of the 2D peak is found to be an unambiguous fingerprint to identify the number of layers for graphene on SiC(0001). A comparison of the Raman data obtained for graphene on SiC(0001) with data for epitaxial graphene transferred to SiO2 reveals that both the G peak blue-shift and the 2D peak lineshape of a single-peak are clearly due to the SiC substrate. The increased linewidth of the 2D peak however stems from the graphene structure itself and not from the substrate.
[1] D. S. Lee et al., Nano Letters, DOI: 10.1021/nl802156w.
[2] C. Riedl et al., Appl. Phys. Lett. 93, 033106 (2008).