Degradation of InGaN∕GaN laser diodes analyzed by microphotoluminescence and microelectroluminescence mappings

The degradation of InGaN∕GaN laser diodes grown by molecular beam epitaxy is analyzed by using surface mapping of the photoluminescence emission on a micrometric scale, which allows the identification of failure regions. This, combined with the mapping of the electroluminescence, suggests two different mechanisms for laser degradation. Increased nonradiative recombination at specific sites along the crystal directions associated with the presence of dislocations lying in the basal plane near the active region is one of these. We also observe an increase in current injection nonuniformities with increasing aging time.