Different degradation behaviors of InGaN/GaN MQWs blue and violet LEDs

InGaN/GaN multiple quantum wells (MQWs) blue and violet light-emitting diodes (LEDs) were stressed under the injection current density of 26.5 A/cm2 for about 400 h at room temperature. Degradation behaviors of blue and violet LEDs were compared. Two stages of degradation were identified in the blue and violet LEDs. At the initial stage, the violet LEDs degraded very fast, but the blue LEDs degraded relatively slow. At later stage, both blue and violet LEDs showed similar degradation rates. Analyses of the L–I and I–V characteristics revealed that the increase of effective nonradiative recombination centers in the active regions was responsible for both blue and violet LED degradations. Rapid degradation of violet LEDs at early stage resulted from dramatical increase of the effective nonradiative centers. More indium in the MQWs might be helpful for better reliability performance of blue LEDs.