Defects in degraded GaN-based laser diodes

We investigate degraded GaN-based laser diodes (LDs) fabricated on epitaxial lateral overgrown (ELO) GaN layers using transmission electron microscopy. The dislocation density in the wing region of the ELO is of the order of 10(6)/cm(2) and there are approximately ten threading dislocations in the laser stripe. Neither dislocation multiplication from the threading dislocations nor any structural changes of the threading dislocations were observed in the devices, which were degraded within approximately one hundred hours under 30 mW continuous operation at 25 degreesC. We can, therefore, conclude that degradation in GaN-based LDs is not responsible for the recombination enhanced dislocation motion that is usually observed in zincblende structure-based LDs. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.