In previous studies, device-quality Si-SiO2 interfaces and dielectric bulk films (SiO2) were prepared using a two-step process; (i) remote plasma-assisted oxidation (RPAO) to form a superficially interfacial oxide (similar to0.6 nm) and (ii) remote plasma enhanced chemical vapor deposition (RPECVD) to deposit the oxide film. The same approach has been applied to GaN-SiO2 system. Low-temperature (300 degreesC) remote N-2/He plasma cleaning of the GaN surface, and the kinetics of GaN oxidation using RPAO process and subcutaneous oxidation during the SiO2 deposition using an RPECVD process have been investigated from analysis of on-line Auger electron spectroscopy (AES) features associated N and O. Compared to single-step SiO2 deposition, significantly reduced defect state densities are obtained at the GaN-dielectric interfaces by independent control of GaN-GaOx (x similar to 1.5) interface formation by RPAO, and SiO2 deposition by RPECVD. (C) 2003 Elsevier Science B.V. All rights reserved.