Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 34: Poster I: III-V Semiconductors
HL 34.16: Poster
Tuesday, March 23, 2010, 18:30–20:30, Poster D2
Surface band structure of GaN(0001)-2×2 — Pierre Lorenz1, Liverios Lymperakis2, Richard Gutt3, •Marcel Himmerlich1, Juergen A. Schaefer1, Jörg Neugebauer2, and Stefan Krischok1 — 1Institut für Physik and Institut für Mikro- und Nanotechnologien, TU Ilmenau, P.O. Box 100565, 98684 Ilmenau, Germany — 2Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany — 3Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastraße 72, 79108 Freiburg, Germany
The results of an in-situ angle-resolved ultraviolet photoelectron spectroscopy investigation of 2×2 reconstructed GaN(0001) surfaces prepared by plasma assisted molecular beam epitaxy are presented. The valence band dispersion was measured by variation of the detection angle with respect to the surface normal along the [1100] (Γ – K) and the [1120] (Γ – M) direction using He I (hν = 21.2 eV) and He II (hν = 40.8 eV) radiation. In addition to the bulk states which exhibit strong dispersion, two non-dispersive surface states at 2 eV and 3 eV below the Fermi level are detected in both directions. In order to identify the origin of these states and to validate the experimentally determined k-dependence of the surface and bulk electron states we performed ab-initio calculations within the density functional theory and we calculated the band structures of different 2×2 surface reconstructions. Based on these calculations we could identify that the aforementioned states arise from a 2×2 N adatom surface reconstruction.