Surface Pretreatment by Low-Temperature O2 Gas Annealing for Performance Improvement in Pt/β-Ga2O3 Schottky Barrier Diodes

We report a method for improving the electrical performance of Pt/ $\beta $ -Ga2O3 Schottky barrier diodes (SBDs) through surface pretreatment using low-temperature O2 gas annealing. We found that subjecting the $\beta $ -Ga2O3 surface to 5 min of O2 gas pretreatment at 400 °C before anode metal deposition resulted in an 18% increase in breakdown voltage ( ${V}_{\text {br}}{)}$ and a 42% improvement in power figure-of-merit (PFOM) compared to control devices. X-ray photoelectron spectroscopy (XPS) analysis revealed that the O2 gas pretreatment caused the oxidation of the Ga $^{{2}+}$ states on the surface, which increased the Schottky barrier height ( ${q}\phi _{\text {b}}{)}$ and improved the ideality factor of the SBDs. However, when the pretreatment time was extended to 15 min, we observed the evidence of the reduction process of the oxidized Ga $^{{2}+}$ , which resulted in a degraded ${V}_{\text {br}}$ and a reduced ${q}\phi _{\text {b}}$ of the SBDs. Overall, our findings suggest that low-temperature O2 gas annealing is a promising approach for engineering the Schottky interface of $\beta $ -Ga2O3 SBDs and improving their performance.