Impact of dislocations on DLTS spectra and degradation of InGaN-based laser diodes

The aim of this paper is to illustrate the dependence of DLTS characteristics and degradation of InGaN-based laser diodes (LDs) on the density of dislocations. Three groups of multi-quantum well LDs with different dislocation densities were submitted to constant current stress, at room temperature: the analysis is based on combined electrical-optical measurements and Deep-Level Transient Spectroscopy (DLTS) investigation was made before and after stress. DLTS results show the presence of a hole trap in all the samples, whose intensity is related to the dislocation density. Constant current stress induces a significant decrease in the optical power (subthreshold regime), not related exclusively to the dislocation density, and the appearance of a new deep level for electrons (point defect generated after stress).