S3-P1: Reliability and lifetime of pseudomorphic UVC leds on AlN substrate under various stress condition

Reliability tests on packaged ultraviolet light-emitting diodes (LEDs) in the ultraviolet-C (UVC) range (< 280 nm) were performed under various temperatures and currents. At higher case temperature, a greater degradation in output power was observed over 1,000 hours. Degradation in output power was also observed at higher operating currents. Some of the output power degradation can be attributed to increased leakage current generated in a subset of devices tested. Physical analysis of a stressed LED indicated a connection between degradation in output power and defects in multi-quantum well (MQW), originating from crystal defects in substrate.