UV LEDs: Performance and Reliability for Commercial InGaN and AlGaN LED Products

The goal of this study was to investigate the state of commercial UV LED products in the 2021 timeframe from the standpoint of initial performance and long-term reliability. In performing this work, 14 different UV LED products, covering the UV-A and UV-C bands, were studied. The initial performance of populations of each product was measured using spectroradiometry and current-voltage (I-V) profiles. Then, the samples were operated at room temperature for up to 3,000 hours, and the performance degradation was followed using spectroradiometry and I-V measurements. In examining the lifetime performance of the UV LEDs, three primary mechanisms of aging were uncovered, and the occurrence of each depended greatly on the UV band and the LED manufacturer. Abrupt failure of the UV LEDs was only observed in specific AlGaN products. The second failure mechanism was the growth of a parasitic diode in parallel with the light-emitting device, and this mechanism, which occurred for products across both bands, resulted in significant reductions in radiant flux. The third aging mechanism identified in this work is package degradation caused by exposure to the UV radiation. This effect is especially pronounced in the UV-A band, which tended to use electronics package materials similar to those of white LEDs. This paper will discuss the evidence of these three degradation mechanisms and their impact on the long-term performance of UV LEDs.