DISLOCATION-MOTION IN GAN LIGHT-EMITTING DEVICES AND ITS EFFECT ON DEVICE LIFETIME

In this study, dislocation motions in GaN-based materials and devices were quantitatively estimated in order to determine why GaN-based ligh t-emitting diodes have remarkable reliability and longevity in spite o f extremely high dislocation density. The dislocation velocity of GaN- based materials was calculated by estimating the activation energy of dislocation, and comparing it with that of GaAs, which are typically u sed for light-emitting devices. It was estimated that the dislocation mobility of GaN-related materials was lower than that of GaAs by a fac tor of approximately 10(-10)-10(-16), at room temperature. Furthermore , dislocation velocity under current injection became about 10(-20) ti mes lower than that of GaAs, under the assumption that the dislocation s in GaN-related materials do not act as nonradiative recombination ce nters. The possibility of degradation under high current densities and high temperature, as would be found in GaN-based laser diodes, is als o discussed. (C) 1997 American Institute of Physics.