Defect Engineering in β -Ga2O3 Schottky Barrier Diodes via Proton Irradiation and Subsequent Low-Temperature Supercritical Fluid Treatment

Abstract This study proposes a defect engineering strategy that combines low-fluence proton irradiation for leakage current (Jr) suppression and subsequent low-temperature supercritical fluid (SCF) treatment for forward conduction characteristic restoration in β-Ga2O3 Schottky barrier diodes (SBDs) with and without NiO guard rings. Mechanistically, the results reveal that proton irradiation and subsequent SCF treatment are not the inverse of each other, as the former primarily introduces gallium vacancies (VGa), whereas the latter mainly passivates oxygen vacancies (VO). On the one hand, for proton irradiation, the introduction of VGa reduces the net carrier concentration (ND – NA), leading to a significant decrease in Jr, accompanied by an increase in specific on-resistance (Ron,sp). On the other hand, for subsequent SCF treatment, the passivation of VO effectively enhances electron mobility rather than substantially restoring ND – NA, thereby maintaining Jr at the irradiated level and considerably reducing Ron,sp. Consequently, through the above defect modulation in bulk β-Ga2O3, SBDs simultaneously achieve a decrease in Jr from 1.16 × 10–5 to 2.01 × 10–8 A·cm–2 at –200 V, a moderate increase in Ron,sp relative to their unirradiated counterparts, and a higher on/off current ratio from 2.28 × 107 to 5.69 × 109 at –200 V. Furthermore, this strategy substantially diminishes the effectiveness of the NiO guard ring in reducing Jr. These findings highlight the potential of this defect engineering as an effective strategy for fabricating high-performance β-Ga2O3 SBDs.