Effects of γ-Ray Irradiation on Bulk Defects and Interface States in β-Ga ₂ O ₃ Schottky Barrier Diodes

This work systematically investigates the irradiation response of$\beta $-Ga2O3Schottky barrier diodes (SBDs) under coupled$\gamma $-ray irradiation among 200 krad, 500 krad, and 1 Mrad(Si), and electrical bias stress of 0, −3, and + 1 V, with emphasis on defect degradation mechanisms. After irradiation, the devices display clear bias-dependent degradation in electrical characteristics. Specifically, reverse-biased operation induces the most severe degradation, characterized by an increase in forward and reverse currents with an obvious decrease in barrier height. The degradation behaviors indicate deteriorated interface properties, with the rate of change slowing at higher irradiation doses. On the contrary, forward-biased operation mainly leads to an increase in reverse current with barrier height remaining unchanged. Based on comprehensive characterization including photoluminescence (PL) spectroscopy and current–voltage ($I$–$V$) measurements, combined with TCAD simulation verification, it is concluded that$\gamma $-ray irradiation would introduce both bulk defects and interface states in$\beta $-Ga2O3SBDs. The specific mechanism for the formation of oxygen vacancies (${V} _{\text {O}}\text {)}$at interface likely triggered by irradiation-ionized holes, which eventually saturates with dose due to the limited${V} _{\text {O}}$–H complexes and pinning effect. Reverse bias enhances the transport of ionized holes to the interface, thereby leading to more severe interface degradation. Concurrently, irradiation-induced gallium vacancies and oxygen interstitial (${V} _{\text {Ga}}$and${\mathrm {O}}_{i}\text {)}$in bulk layers function as acceptor-like defects, leading to the carrier removal in drift layer that primarily account for the minor degradation observed in forward-biased device. The findings offer useful understanding for improving the reliability of$\beta $-Ga2O3SBDs in practical aerospace applications.