Reliability analysis of GaN-based light emitting diodes for solid state illumination

In this paper, we have discussed the effect of electrical stress onGaN light emitting diode (LED). With the lapse of time, the LED withan applied large current stress can reduce its current more thanwithout such a stress under a large forward-voltage drop. Itsscanning electron microscopy (SEM) image shows that there existseveral pits on the surface of the p-metal. With an electricalstress applied, the number of pits greatly increases. We also findthat the degradation of GaN LED is related to the oxidized Ni/Auohmic contact to p-GaN. The electrical activation of H-passivated Mgacceptors is described in detail. Annealing is performed in ambientair for 10 min and the differential resistances at a forward-voltagedrop of 5,V are taken to evaluate the activation of the Mgacceptors. These results suggest some mechanisms of degradationresponsible for these phenomena, which are described in the paper.