Published in Appl. Phys. Lett. 89, 171920 (2006).
Electronic States of Oxidized GaN(0001) Surfaces
Y. Dong (a), R. M. Feenstra (a), and J. E. Northrup (b)
(a) Dept. Physics, Carnegie Mellon University, Pittsburgh, PA 15213
(b) Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, CA 94304
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.
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