High-temperature degradation of InGaAsP/InP light emitting diodes

Abstract

The results of accelerated aging study of high radiance double heterostructure InGaAsP/InP light emitting diodes (LED’s) are reported. Under a forward bias of 5 kA/cm2 and a junction temperature of 140° C, these devices show a gradual degradation of ∼5% after 5000 h of aging. However, at temperatures above ≊190° C, a new mechanism is observed, resulting in rapid degradation, down to ∼20% of the initial power output in 300 h at 200 °C, even without bias. Electron beam induced current and transmission cathodoluminescence analysis show formation of 〈110〉 dark line defects in the InP buffer layer originating at microscopic inclusionlike defects. While it is not clear that this mechanism is relevant for normal LED operation, its presence greatly complicates interpretation of the accelerated aging experiments.