Niobium oxides films on GaN: Photoelectron spectroscopy study

Non-stoichiometric niobium oxides were grown on p-GaN(0001) substrates using physical vapor deposition of Nb under ultrahigh vacuum (UHV) enriched with oxygen. The film consisted mainly of NbOx and Nb2O5 phases. NbO2 compound as well as trace amounts of NbO and Nb in metallic were also present in the film. Then, in order to eliminate non-insulating fractions, the method of oxygen-ion implantation followed by annealing was used. This resulted in a formation of insulator films composed almost only of Nb2O5 compound. The surface of the cleaned substrate and niobium oxides/GaN interfaces (prior and after an O-ion implantation) were characterized in situ by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The result allowed to determine band offsets at the Nb2O5/GaN interface.

Automated summary

Non-stoichiometric niobium oxides were grown on p-GaN(0001) substrates using physical vapor deposition, and non-insulating fractions were eliminated through oxygen-ion implantation and annealing, resulting in insulator films composed mostly of Nb2O5 compound. The band offsets at the Nb2O5/GaN interface were determined using XPS and UPS characterization.