Induced changes in surface band bending of n -type and p -type AlGaN by oxidation and wet chemical treatments

Abstract

The surface chemistry and electrical properties of p -type and n -type AlGaN surfaces were studied via x-ray photoelectron spectroscopy before and after oxidation and wet chemical treatments. Shifts in the surface Fermi level were measured with the change in onset of the valence-band spectra. Oxidation and HF and (N H4) 2 Sx treatments on p -type AlGaN (n -type AlGaN) led to an increase (the reduction) in the surface band bending due to more N vacancies and N vacancies being occupied by S (i.e., donorlike states) than Al vacancies and Ga vacancies (i.e., acceptorlike states) near the p -type AlGaN (n -type AlGaN) surface region. The changes in surface chemistry indicate that oxidation and wet chemical treatments alter the surface state density through the formation of more donorlike states. © 2006 American Institute of Physics.