Research on Lifetime and Reliability of Deep Ultraviolet LEDs under Current Stress with Different Sizes and Packaging Methods

AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) have garnered significant attention in recent years due to their potential applications in sterilization and disinfection. However, issues such as short lifetime and low reliability remain prominent. To investigate these issues, this paper examines the life degradation patterns of AlGaN-based DUV LEDs under current stress, with different chip sizes and packaging methods, and provides a detailed analysis of their degradation mechanisms. Accelerated aging experiments under current stress were conducted on DUV LEDs. These LEDs had three different chip sizes—small, medium, and large—and four methods of packaging: three-pad ball lens, five-pad ball lens, five-pad flat lens, and flat-panel bracket without lens. The results revealed that the light output power decays faster with increasing chip size over time. After 1000 hours of aging tests, the decay in light output power for small, medium, and large chips was found to be 13.1%, 18.2%, and 34.5%, respectively. The forward voltage and series resistance of the LEDs increased with aging time, while the peak wavelength remained relatively stable. Different packaging methods significantly influenced the lifetime of DUV LEDs, where the choice of lens and the depth of the packaging bracket dam affected the heat dissipation efficiency, thereby impacting the LED lifetime. In this experiment, LEDs with ball lens packaging showed the best lifetime, reaching 8971 hours. This study reveals the degradation mechanisms of AlGaN-based DUV LEDs under current stress and suggests that optimizing chip size and packaging method could effectively enhance the lifetime of AlGaN-based DUV LEDs.