Effects of post-deposition annealing ambient on band alignment of RF magnetron-sputtered Y(2)O(3) film on gallium nitride

The effects of different post-deposition annealing ambients (oxygen, argon, forming gas (95% N(2) + 5% H(2)), and nitrogen) on radio frequency magnetron-sputtered yttrium oxide (Y(2)O(3)) films on n-type gallium nitride (GaN) substrate were studied in this work. X-ray photoelectron spectroscopy was utilized to extract the bandgap of Y(2)O(3) and interfacial layer as well as establishing the energy band alignment of Y(2)O(3)/interfacial layer/GaN structure. Three different structures of energy band alignment were obtained, and the change of band alignment influenced leakage current density-electrical breakdown field characteristics of the samples subjected to different post-deposition annealing ambients. Of these investigated samples, ability of the sample annealed in O(2) ambient to withstand the highest electric breakdown field (approximately 6.6 MV/cm) at 10(−6) A/cm(2) was related to the largest conduction band offset of interfacial layer/GaN (3.77 eV) and barrier height (3.72 eV).