Life tests and failure mechanisms of GaN-AlGaN-InGaN light emitting diodes

Our studies of device lifetime and the main degradation mechanisms in Nichia blue LEDs date back to Spring 1994. Following the initial studies of rapid failures under high current electrical pulses, where metal migration was identified as the cause of degradation, we have placed a number of Nichia NLPB-500 LEDs on a series of cw life tests. This work reviews the failure analysis that was performed on the degraded devices and the degradation mechanisms that were identified.