Dresden 2009 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 42: Interfaces/surfaces

HL 42.5: Vortrag

Donnerstag, 26. März 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.