Gamma-Irradiation-Accelerated Degradation in AlGaN-Based UVC LEDs Under Electrical Stress

Abstract

The effect of gamma ( $\gamma $ )-irradiation on AlGaN-based light-emitting diodes (LEDs) in the short-wavelength ultraviolet (UVC, 210–280 nm) spectral range under electrical stress is characterized by electroluminescence and current–voltage measurement. Different from previous reports that $\gamma $ -irradiation can hardly damage nitride devices, we observe that the optical power decreases and leakage current increases obviously after electrical stress under $\gamma $ -irradiation. To delve into the nature of degradation, variation of defects is studied using temperature-dependent low-frequency noise measurement. After stress, the ~0.78-eV defects attributed to N antisite are generated and lead to device degradation, which is accompanied by a reduction of the intrinsic Ga vacancy with an energy level of ~0.38 eV. The variation of defects after stress in $\gamma $ -irradiated environment is more evident than that in nonirradiated environment, which is well corresponding to the performance degradation behavior. In conclusion, $\gamma $ -irradiation is found to accelerate degradation induced by electrical stress, and the study can help improve irradiation resistance in AlGaN-based UVC LEDs.