Decay of electroluminescence in GaAs diodes

It has been reported that radiation from GaAs electroluminescent diodes operated under forward bias conditions gradually decreases with time. This paper, which is a more comprehensive study of the effect, describes the results of a large-scale, systematic aging study (500 diodes, each aged about 2000 hours) for a wide range of fabrication parameters and stress conditions. The fabrication variables encompass surface preparation, encapsulation, and crystal types. The stress conditions included current densities from 0 to 500 A/cm²at room temperature and from 0 to 130 A/cm²at 65°C. The effect of the above parameters on the rate of decay of the light output will be presented. A particular method of junction preparation which produced a marked decrease in the light decay rate will also be discussed. The observed data will be interpreted by considering a competing nonradiative recombination process through intermediate energy levels.