Luminescence degradation of InGaN/GaN violet LEDs

The changes of optical output power and electrical property of InGaN/GaN violet light-emitting diodes (LEDs) with different indium compositions have been investigated, under injection current densities of 26.5 and 79.5 A/cm2. When injection current density was 26.5 A/cm2, output power of LEDs with low indium composition (2%) degraded more rapidly than the ones of 10% indium inside. At a large injection level of 79.5 A/cm2, the difference in optical power degradation between LEDs of 10% and 2% indium composition became small. A discussion based on the results of current–voltage curves , L–I curves, as well as optical power degradation with stress time indicates that LEDs with 10% indium composition have better performance than LEDs with 2% indium composition. It is believed that the indium enhancement of radiative recombination helps preventing defect generation during electrical stress.