Characterization and simulation of 280 nm UV-LED degradation
Mengwei Su, Xinglin Zhu, Qi Guo, Zhiqiang Chen, Shaodong Deng, Ziqian Chen, Yukun Wang, Jianyu Deng, Wenhong Sun
Abstract
In this paper, we investigated the degradation of 280 nm ultraviolet light emitting diodes (UV-LEDs) using both optical and electrical characterization methods. By capacitance–voltage methods, we were able to reveal that carriers in the quantum wells closer to the sapphire substrate would redistribute with aging time and stress currents. We compared these distributions with simulations and found that both the polarization charges at the AlGaN/AlGaN heterostructure interface and the quantum well doping were significantly affected by the stress. These results indicated that the migration and diffusion of donor impurities/dislocations under the current flow could lead to the deterioration of the quantum well crystal quality and contribute to the attenuation of optical power. Our study suggests a novel mechanism for degradation of UV-LEDs, and the developed techniques provide a new approach for future reliability analysis.