Gamma irradiation-induced trap behavior in AlGaN-based UV-C LEDs causing accelerated failure under electrical stress

Abstract

The effects of traps on the degradation of AlGaN-based deep ultraviolet light-emitting diodes (LEDs) under gamma (γ) irradiation and/or constant current stress are investigated in this work. Radiation significantly accelerates the degradation rates of devices under electrical stress. Although γ irradiation can penetrate the entire chip, irradiation stress primarily affects the region near the interface between the p-type layer and the multi-quantum well, regardless of whether electrical stress is added at the same time. Compared with electrical stress, the number of defects with an activation energy of approximately 0.1 eV substantially increases under irradiation-electrical stress according to admittance spectroscopy. These defects are speculated to constitute a complex of Mg-related substitutive impurities and Ga vacancies within the electronic barrier layer, and they are considered to constitute the primary mechanism responsible for the accelerated failure of devices under irradiation-electrical stress. In this study, an in-depth analysis of the difference in defect behavior caused by irradiation and electrical stresses in UV-C LEDs is provided, and possible optimization directions for the fabrication of real high-radiation-hardness AlGaN-based devices under radiation and electrical stress are suggested.