Influence of substrate dislocations on epitaxial layers studied by photoluminescence microscopy and topography

Nonradiative recombination centers in epitaxial heterostructures are studied with spectrally selective photoluminescence microscopy (PLM). Characteristic patterns of the dislocation density distribution in GaAs substrates are reproduced in the PLM images of quantum wells and buffer layers. The onset of strain relaxation in InGaAs/GaAs multiple quantum well (MQW) lasers is observed to depend on the number of quantum wells, substrate dislocations and doping of the MQWs. Line defects along two different low index crystal orientations are observed.