Research on degradation characteristics of 253 nm AlGaN-based micro-LEDs for charge management application

Ultraviolet-C micro-light-emitting diodes (UVC micro-LEDs) are promising as a superior alternative to existing UV light sources for charge management in the aspect of gravitational wave detection due to their better performance. However, the degradation characteristics and recombination mechanisms of UVC micro-LEDs have not been sufficiently studied. In this paper, the electrical characteristics of UVC micro-LEDs under various stress conditions are analyzed, and a significantly low ideality factor and a stable emission spectrum are achieved despite the increase in the leakage current due to trap-assisted tunneling (TAT) caused by defects. Then, we proposed to utilize the carrier recombination model to analyze the efficiency droop and the recombination variation during the degradation process. The results indicate that a larger injection current will not only intensify the Shockley-Read-Hall (SRH) recombination but enhance the Auger recombination and carrier leakage via the defects generated by stress currents, thus weakening the radiative recombination. The negative variation of the light output power (LOP) and the influence of the junction temperature resulting from large injection currents are also discussed. This work provides insights into the degradation mechanism and efficiency droop of UVC micro-LEDs with aging, which is essential to improve their performance and reliability in charge management and other practical applications.