Determination of band alignment between GaO_x and boron doped diamond for a selective-area-doped termination structure

An n-GaO_x thin film is deposited on a single-crystal boron-doped diamond by RF magnetron sputtering to form the pn heterojunction. The n-GaO_x thin film presents a small surface roughness and a large optical band gap of 4.85 eV. In addition, the band alignment is measured using x-ray photoelectron spectroscopy to evaluate the heterojunction properties. The GaO_x/diamond heterojunction shows a type-II staggered band configuration, where the valence and conduction band offsets are 1.28 eV and 1.93 eV, respectively. These results confirm the feasibility of the use of n-GaO_x as a termination structure for diamond power devices.