The mechanism of degradation and failure in NiO/β-Ga₂O₃ heterojunction diodes induced by the high-energy ion irradiation

This work investigated the single-event effects (SEE) of NiO/β-Ga₂O₃ heterojunction diodes (HJDs) irradiated by 1.86 GeV tantalum ions with linear energy transfer over 80 MeV cm²/mg. The HJDs exhibited radiation responses with the early single-event leakage current (SELC) degradation until the fatal single-event burnout (SEB) failure, which was far below their breakdown voltages. Meanwhile, the surface morphology revealed the SELC damage expressed as burnout of topside NiO and metal stacks, while the SEB damage was observed as a burned hole in the β-Ga₂O₃ epitaxial layer. According to technology computer aided design simulations, the thicker p-type region in HJDs could further alleviate the electric field crowding effect exacerbated by the heavy-ion strike because of the extension of charge distribution in the p-type region. The SEB threshold was raised to 250 V by thickening the NiO layer to 300 nm. As for the SELC degradation process along with the burnout of topside stacks in HJDs, we supposed the probable reason was the intolerance of NiO to the high electric field under the SEE. This paper analyzed the SEE mechanism in β-Ga₂O₃ diodes and paved the way for heavy-ion irradiation hardening.