Defect compensation and recombination characteristics of NiO/ β -Ga2O3 heterojunctions under electronic-stopping-dominated swift heavy-ion irradiation

Understanding how irradiation influences recombination-active defects and carrier transport is crucial for establishing the radiation tolerance of Ga2O3 power electronics. Here, we investigate the effects of 1.86 GeV 181Ta31+ swift heavy-ion irradiation on NiO/β-Ga2O3 heterojunction power diodes. Capacitance profiling reveals a pronounced near-surface carrier-removal rate of 9.2 × 107 cm−1 on the β-Ga2O3 side, indicating partial donor compensation in the depletion region. Deep-level transient spectroscopy further reveals irradiation-induced compensation of electrically active defects, in which the E2-related traps (EC-0.818 eV) are no longer resolved within the investigated temperature range, while E2* traps shift deeper from EC-0.670 to EC-0.733 eV and bulk-distributed E9 traps (EC-0.392 eV) remain nearly unchanged. Correspondingly, the subthreshold forward-bias transport behavior changes from tunneling-assisted recombination with a peak ideality factor (η) of 20.75 to a conventional Shockley–Read–Hall recombination mechanism (η≈2) after irradiation, whereas the reverse transport characteristics remain largely consistent with Poole–Frenkel emission with a nearly unchanged activation energy. These results suggest that electronic-stopping-dominated irradiation is accompanied by the compensation of electrically active defects and enhanced carrier compensation within the depletion region, which are associated with the observed changes in the dominant recombination behavior of β-Ga2O3 heterojunction devices under the present irradiation condition.