Formation of Thin Native Oxide Layer on n-GaN by Electrochemical Process in Mixed Solution with Glycol and Water

Abstract

In this paper, we report on the feasibility of oxidizing n-GaN by an electrochemical process in a mixture containing an aqueous solution of tartaric acid and propylene glycol. Photons generated by UV illumination were supplied at the electrolyte–GaN interface during the oxidation process. In the constant-voltage mode, X-ray photoelectron spectroscopy analysis revealed that relatively thick Ga oxide layer formed on the n-GaN surface. However, the oxide surface was very rough. In addition, we found metallic Ga components in the oxide layer or at the oxide–GaN interface for longer oxidation times. On the other hand, a thin Ga2O3 layer with a smooth surface was grown by a constant-current process.