Date of Original Version
2006
Type
Article
Published In
Appl. Phys. Lett. 89, 171920 (2006)
Abstract or Table of Contents
The structure and electronic properties of oxidized (0001) surfaces of GaN grown by plasma-assisted molecular beam epitaxy are investigated by scanning tunneling microscopy/spectroscopy, Auger electron spectroscopy, and first-principles theory. For oxygen exposure at room temperature an amorphous gallium oxide layer is found to form, resulting in a distribution of midgap electronic states extending out from the GaN valence band edge. The influence of these states on the electron concentration in buried AlGaN/GaN heterojunctions is discussed.