Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)
O 17.77: Poster
Montag, 26. März 2007, 17:30–20:30, Poster C
Oxidation of lateral polarity heterostructure GaN — •Pierre Lorenz, Vadim Lebedev, Richard Gutt, Juergen A. Schaefer, Oliver Ambacher, and Stefan Krischok — Institut für Mikro- und Nanotechnologien, TU Ilmenau, P.O. Box 100565, 98684 Ilmenau, Germany
We study GaN-based lateral polarity heterostructures (LPH) for nonlinear optics using surface sensitive techniques. The GaN was grown on Al2O3 substrates by molecular beam epitaxy (MBE). The N-face was directly grown on Al2O3 whereas the Ga-face was grown on a 20 nm thick AlN nucleation layer structured by photolithography. The examined LPH GaN samples consist of a stripe pattern with a periodicity of 1-100 µm of the N-face and Ga-face domains. The GaN surface properties were studied using atomic force microscopy (AFM), X-ray and ultraviolet photoelectron spectroscopy (XPS, UPS). The samples exhibit smooth Ga-face regions and lower quality N-face areas, separated by sharp and well defined inversion domain boundaries. The changes in the work function and the valence band structure are investigated upon adsorption of oxygen at room temperature. Special attention has been drawn to the interaction of O2 with the inversion domain boundary region by employing photoelectron emission microscopy (PEEM).