Current crowding as a major cause for InGaN LED degradation at extreme high current density

Abstract

To increase the optical output of a lighting system, high power Light Emitting Diodes are requested to operate at high currents; however, the maximum drive current is limited by the reliability of the devices. With this work we report on the effects of step stress carried out at increasing bias up to extreme current levels. By means of optical, electrical and photoluminescence analysis we hypothesize that the optical power decrease is related a degradation of the current transport layers of the devices and that an accurate control of the current crowding is crucial in extending the operating range of high power devices.