Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Graphene IV
O 82.2: Vortrag
Freitag, 26. März 2010, 11:30–11:45, H31
High Resolution Electron Energy Loss Spectroscopy on Graphene/SiC(0001) — •Roland J. Koch1, Michael Endlich1, Thomas Haensel1, Syed Imad-U. Ahmed1, Thomas Seyller2, and Juergen A. Schaefer1,3 — 1Institut für Physik and Institut für Mikro- und Nanotechnologien, TU-Ilmenau, Ilmenau, Germany — 2Lehrstuhl für Technische Physik, Universität Erlangen-Nürnberg, Erlangen-Nürnberg, Germany — 3Department of Physics, Montana State University, Bozeman, Montana, USA
The recent experimental realization of single-layer graphene sheets has led to intense efforts to understand its electronic and vibrational properties in the context of solid state materials physics. In this contribution we investigate the interaction of epitaxial graphene with SiC(0001) using high resolution electron energy loss spectroscopy (HREELS). The focus in this contribution is on the coupling of charge carriers in semi-metallic graphene with the optical phonons of SiC(0001). Due to this coupling the surface optical phonons, the so called Fuchs-Kliewer phonons, completely vanish and two new modes ω− and ω+ are observed instead. The energetic position and intensity of these modes depend strongly upon the momentum transferred parallel to the interface (q∥), which we investigated in the regime of 0.005 Å−1 to 0.03 Å−1. Simulating our HREELS-data using dielectric theory and solving the Poisson- and Schrödinger equations self consistently allows us to determine the carrier density distribution and the conduction band edge normal to the plane of the graphene/SiC heterostructure.