The Mechanisms of Current Induced Degradation in a GaAs Light Emitting Diode

Abstract

The degradation of radiant power output (Po) for silicon doped GaAs infrared emitting diodes was established for dc current stress levels ranging from 70 to 175 A/cm2. Through an analysis of the forward I-V data and specially performed tests, it was de-termined that the initial degradation was due to increases in the space charge recom-bination current while later degradation was due to decreases in the diffusion current. The initial changes in the space charge recombination current were caused by the diffusion of zinc atoms to the junction region via the Longini mechanism. Zinc diffusion also resulted in an initial increase in Po both under stress and room temperature storage conditions. The mechan-ism responsible for the decrease in the diffusion current was not identified, but most probably involved the silicon dopant atoms.