Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 10: Semiconductor Substrates: Epitaxy and Growth
O 10.12: Talk
Monday, February 25, 2008, 16:00–16:15, MA 042
Structure and morphology of graphene layers on SiC(0001) — •Christian Riedl1, Chariya Virojanadara1, Christian Ast1, Alexei Zakharov2, Klaus Heinz3, and Ulrich Starke1 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany — 2MAX-Lab, Lund University, Box 118, Lund, S-22100, Sweden — 3Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany
We report on the development of graphene layers on the 4H-SiC(0001) surface by high temperature annealing under ultra high vacuum conditions focusing on two issues: firstly, we analyze the precursor stage of graphitization, the (6√3×6√3)R30∘-reconstruction. By means of low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) we discuss the role of three observed phases with periodicities (6√3×6√3)R30∘, (6×6) and (5×5) for three different preparation conditions [1]. Secondly, the growth of epitaxial graphene is discussed in detail. Depending on tunneling bias and tip conditions STM micrographs show the graphene layers with atomic resolution and its long-range epitaxial relation to the underlying substrate [1]. We show that LEED pattern and intensities can be applied quantitatively to monitor the number of graphene layers during the preparation procedure. We correlate LEED fingerprints with angular resolved photoelectron spectroscopy (ARUPS) from HeII excitation, high resolution x-ray photoelectron spectroscopy (XPS) and low energy electron microscopy (LEEM).
[1] C. Riedl et al., Phys. Rev. B, in print