The role of surface pretreatment by low temperature O2 gas annealing for β -Ga2O3 Schottky barrier diodes

β-Ga2O3 based Schottky barrier diodes (SBDs) with low temperature O2 gas annealing pretreatment is investigated. Improved electrical performance and uniformity are seen, which is expected that oxygen vacancies at the surface are passivated and Schottky barrier height (SBH) is lowered upon this pretreatment. The mechanism is interrogated by x-ray photoelectron spectroscope (XPS) measurements and first-principles modeling. The SBH lowering is consistent with the change in the interface dipole at the W/Ga2O3 interface, as evidenced by XPS results. The first principles modeling explained that SBH decrease is caused by the VO elimination. This work shows an effective approach to engineering the interface with improved electrical performance of β-Ga2O3 SBDs.