Systematic root cause analysis for GaP green light LED degradation

High-brightness light-emitting diodes (LEDs) are now commonly employed in many applications. In order to ensure long-term applications with insignificant degradation, the root cause analysis of their degradation is important. While failure analysis of failed LEDs can usually be traced with observable defects, the defects that cause LEDs to degrade are generally less obvious. In this paper, we present a systematic method to identify the root cause of green GaP LED degradation. The various steps in the procedure from nondestructive to destructive analysis are described, and the root cause is found to be the excessive doping of zinc in the p-layer.