Degraded GaN-based laser diodes, fabricated on epitaxial laterally overgrown GaN layers, were investigated by means of transmission electron microscopy. The dislocation density in the wing region of the epitaxial lateral overgrowth was of the order of 106/cm2, and there were some 10 threading dislocations in the laser stripe. No dislocation multiplication from the threading dislocations, or any structural changes in the threading dislocations, were observed in devices which degraded within about 100h under 30mW continuous operation at 25C. It was therefore concluded that degradation in GaN-based laser diodes was not responsible for the recombination-enhanced dislocation motion that was usually observed in zincblende-structure laser diodes.

Defects in Degraded GaN-Based Laser Diodes. S.Tomiya, S.Goto, M.Takeya, M.Ikeda: Physica Status Solidi A, 2003, 200[1], 139-42