ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Mirror facets of broad area AlGaAs SQW 808 nm lasers with fast degradation of the output power have been investigated by photoluminescence microscopy (PLM), electroluminescence microscopy, and micro-photocurrent spectroscopy techniques. Over 2000 images of the photoluminescent light emitted from the facets of approximately 20 degraded laser bars have been made. Repeating patterns associated with the degradation have been noted and classified. Degraded lasers have dark lines on the mirror facet surface which are inclined from the epitaxial plane by 55°. Pairs of such lines often form V-shaped patterns. The orientation of the observed features suggest they are planar or line defects lying the the {111} crystallographic planes. The defects demonstrate a reduction in the lifetime of nonequilibrium electron–hole pairs and increased density of states in the forbidden gap of the active region of the laser structure, and are directly related to laser failure. Observations of the evolution in size and contrast of PLM patterns with ageing suggest the defects were initially created in the active region side of the laser structures during crystal growth or during the mounting procedure, and later propagate in the {111} planes, stimulated by the lasing action. We interpret the V formation to be a way to relax a compressive strain in the epitaxial plane. A dislocation on the {111} planes could actually translate the portion of the crystal bounded by the V upwards (away from the mounting of the crystal), in response to compressive strain. © 2000 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.372328
