The mechanism of single-event burnout in NiO/ <i>β</i> -Ga2O3 heterojunction diodes under atmospheric neutron irradiation

Abstract

This study investigates the mechanism of single-event burnout (SEB) in NiO/β-Ga2O3 heterojunction diode (HJD) induced by atmospheric neutron. The degradation mode and physical mechanism are evaluated through current–voltage (I–V) measurement, emission microscopy, technology computer-aided design (TCAD), focused ion beam (FIB), and scanning electron microscopy (SEM) analysis. The experimental results indicate that the reverse bias voltage is a critical factor influencing SEB failure of NiO/β-Ga2O3 HJD. SEB occurs when the reverse bias reaches 750 V, characterized by a sharp increase in cathode current and catastrophic failure. Electrical characterization after SEB shows complete loss of rectifying behavior and reverse voltage withstand capability. TCAD simulations indicate that secondary particles generated by neutron interactions produce electron–hole pairs along their trajectory, which accelerate under the strong electric field in the drift layer, triggering impact ionization and current surge. Intense impact ionization leads to lattice temperature exceeding the melting point of β-Ga2O3, causing thermal runaway and burnout. FIB and SEM analysis confirms melt voids spanning the entire drift layer and part of the substrate, consistent with simulation results. These findings clarify the SEB mode and mechanism in NiO/β-Ga2O3 HJD and provide insights for evaluating their performance in harsh radiation environments.