On early stage degradation in Zn diffused GaAs LED

Abstract Life tests performed at high temperature on zinc-diffused GaAs LED show a decrease of emitted power which is accompanied by an apparent shift of the peak emission toward shorter wavelengths. This shift is also noted in photoluminescence and photoconduction spectra. A careful analysis of these measurements reveals that the effect must be attributed to a change in absorption coefficient of the zinc-diffused front region, surface recombination velocity and electron diffusion length remaining essentially constant. Laser irradiated LEDs also show this effect; consequently it has to be attributed to a recombination activated degradation of the P region, possibly zinc precipitation.