Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 44: Invited talk: S. Krischok
HL 44.1: Invited Talk
Wednesday, March 24, 2010, 14:00–14:30, H15
Surface characterisation and reactivity of clean GaN(000±1) surfaces — Pierre Lorenz1, Richard Gutt2, Marcel Himmerlich1, Juergen A. Schaefer1, and •Stefan Krischok1 — 1Institut für Physik and Institut für Mikro- und Nanotechnologien, TU Ilmenau, P.O. Box 100565, 98684 Ilmenau, Germany — 2Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastr. 72, 79108 Freiburg, Germany
This contribution summarises our present understanding of the surface properties of reconstructed GaN(000±1) thin films grown by plasma assisted molecular beam epitaxy and the early stages of the interaction with selected small molecules. The intrinsic properties of the pure GaN samples have been analysed in-situ following the epitaxial growth mainly utilizing photoelectron spectroscopy (XPS and angular resolved UPS). Special attention is paid to the presence of reconstruction-induced surface states and their influence on surface band bending and electronic properties as well as the angular dependence of the valence band spectra. The initial surface-adsorbate-interaction and the related changes of surface electronic properties are discussed for the model molecules O2 and H2O. The observed surface states reveal a high reactivity and vanish upon the initial stages of oxidation. Furthermore, adsorbate-related electron states are formed which will be discussed in terms of changes in surface dipole, bend bending and work function. A comparison of the reactivity towards O2 and H2O between different GaN surface modifications will be made.