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O: Fachverband Oberflächenphysik

O 15: Focused Session: Epitaxial Graphene II

O 15.4: Talk

Monday, March 23, 2009, 16:00–16:15, SCH 251

Dynamical properties of cubic and hexagonal silicon carbide from Si-rich to C-rich reconstructions up to graphene formation — •Juergen A. Schaefer and Roland J. Koch — Institut für Physik and Institut für Mikro- und Nanotechnologien, Technische Universität Ilmenau, P. O. Box 100565, 98684 Ilmenau, Germany

Using high resolution electron energy loss spectroscopy (HREELS) in conjunction with low energy electron diffraction (LEED) and X-ray induced photoelectron spectroscopy (XPS), we have studied the vibrational properties of cubic SiC (001) and hexagonal SiC (0001) surface reconstructions from Si-rich to C-rich SiC surfaces, and up to graphene formation in the hexagonal case. Upon subsequential annealing from 30 K up to 1500 K, the coupling between the longitudinal optical phonons, the so called Fuchs-Kliewer phonons, and the carrier plasmons that originate from the presence of bulk dopants and / or from the layered semimetallic character of graphene and few layer graphene (FLG), drastically influence the HREELS-spectra. It seems that the latter graphitic layer is essentially unperturbed by the substrate underneath. The measured phonon dispersion strongly resembles that of graphite.