Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 42: Interfaces/surfaces
HL 42.5: Talk
Thursday, March 26, 2009, 10:30–10:45, POT 51
Initial stages of GaN(0001)-2x2 - oxidation — •Pierre Lorenz1, Richard Gutt2, Juergen A. Schaefer1, and Stefan Krischok1 — 1Institute of Physics and Institute of Micro- und Nanotechnologies, Technical University Ilmenau, P.O. Box 100565, D-98684 Ilmenau, Germany — 2Fraunhofer Institute for Applied Solid State Physics, Tullastr. 72, 79108 Freiburg, Germany
We studied the initial oxidation stages of 2x2 reconstructed Ga-face GaN(0001) grown in-situ by PAMBE. The oxidation process was characterized using X-ray and ultraviolet photoelectron spectroscopy (XPS, UPS), as well as reflection high energy electron diffraction (RHEED). In particular, the evolution of the valence band structure, the work function and the core levels of gallium and nitrogen as well as the increase of the oxygen O 1s emission were studied in combination with the corresponding RHEED pattern as a function of oxygen exposure. The clean GaN(0001)-2x2 surface exhibits two surface states at 2 eV (S1) and 3.5 eV (S2) below the Fermi level. The exposure to O2 results in two well pronounced valence band structures at binding energies of about 6 eV and 11 eV, respectively, which are caused by the adsorbed oxygen. The 2x2 reconstruction as well as the S1 state disappear rapidly, revealing an extremely high reactivity of the as grown GaN surface, whereas the S2 state vanishes considerably slower.