Low-temperature supercritical fluid treatment for electrical performance restoration and enhancement in degraded β-Ga₂O₃-based diodes: Synergistic effects of trap passivation, interface optimization, and band structure modification

The low-temperature supercritical fluid (SCF) process demonstrates significant potential in enhancing electrical performance and restoring degraded characteristics of (ultra-)wide bandgap semiconductor devices. This study investigated the effect of low-temperature supercritical N₂O fluid treatment on ultrawide-bandgap β-Ga₂O₃-based diodes with degraded electrical properties exposed to the storage environment, including Ni/β-Ga₂O₃ Schottky barrier diodes (SBDs), Ni/β-Ga₂O₃ SBDs with NiO rings (SBDs-GR), and NiO/β-Ga₂O₃ PN junction diodes (PNDs). Electrical characterizations demonstrated that SCF treatment on degraded diodes significantly improved forward conduction characteristics and substantially reduced leakage current, primarily arising from the synergistic effects of trap passivation, interface optimization, and band structure modification. On the one hand, the restoration of forward saturation current density of degraded diodes after SCF treatment was accompanied by electron trap passivation. On the other hand, the reduction of leakage current after SCF treatment in SBDs and SBDs-GR was closely related to the suppression of Poole-Frenkel emission and Fowler-Nordheim tunneling. Besides, comparative analysis indicated that the SCF treatment exerted more pronounced effects on SBDs and SBDs-GR than on PNDs. This work substantiates the capability of SCF processing to restore degraded β-Ga₂O₃-based diodes while providing critical experimental evidence and theoretical support for its application in enhancing the electrical performance of β-Ga₂O₃-based devices.