Radiation-induced anion-vacancy dynamics in wide-band-gap semiconductors for power devices.

In space or even terrestrial radiation environments, single energetic-ion strikes can cause a sharp rise in the leakage current of wide-band-gap semiconductor power devices under reverse bias (single event leakage current). At some high voltage, the current increase resulting from a single ion strike can short the device, leading to single-event burnout. It is known that such ion strikes generate very high concentrations of electron-hole pairs along the ion path that mediate the current increase and concomitant Joule-heating rise, but the nature of new conducting paths that sustain the higher current after the strike has not been extensively investigated. We report atomic-scale density-functional-theory calculations that unveil the creation of conducting nanowires made up by anion vacancies. Cation vacancies generated by the striking ion literally spout anion vacancies that easily migrate along anion “chains” within the ion path, forming conducting nanowires. Comparisons of the calculated energy barriers that need to be overcome by the Joule heating to initiate the process is a measure of the robustness of different wide-band-gap semiconductors such as SiC, GaN, AlN, and Ga₂O₃ for power devices.