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.