The role of N-related point defects in the degradation process of ZnSe-based white light-emitting diodes

The role of N-related point defects in the degradation process of ZnSe-based white light-emitting diodes under operation was investigated. The generation rate of microscopic dark spots, which do not correspond to the original stacking faults or threading dislocations in the epilayer, was found to correspond to the initial concentration of the N-related deep-level H0 (ET−Ev=0.8±0.2eV) in the p-ZnMgSSe layer. Devices with high initial H0 concentrations resulting from thermal treatments, at the same time, showed a drastic reduction in their net acceptor concentrations. The origin of this effect is believed to be due to the deactivation of the N acceptor, rather than the hole-trapping effect of the H0 center.