Low-temperature formation of Ga-oxide/GaN interface with remote oxygen plasma and its interface properties

The Ga-oxide/GaN structures formed by remote oxygen plasma (ROP) exposure at various temperatures (T s) and times have been systematically investigated. X-ray photoelectron spectroscopy clarified the formation of Ga2O3 layers with close-to-stoichiometric composition and a slight N incorporation of ~6 at. %. Also, we found that a high T s increases the intensity of a signal related to the N–O bond, which is located near the Ga-oxide/GaN interfaces. Total photoelectron yield spectroscopy (PYS) also revealed that the ROP exposure at T s of 300 °C produces fewer filled defect states in the bandgap of GaN than at 500 °C. This difference in the filled defect states could be attributable to the amount of N–O bonds at the interface.