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

The effect of gamma (γ)-irradiation on AlGaNbased 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 γ-irradiation can hardly damage nitride devices, we observe that the optical power decreases and leakage current increases obviously after electrical stress under γ-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 γ-irradiated environment is more evident than that in nonirradiated environment, which is well corresponding to the performance degradation behavior. In conclusion, γ-irradiation is found to accelerate degradation induced by electrical stress, and the study can help improve irradiation resistance in AlGaN-based UVC LEDs.