Near-infrared cathodoluminescence imaging of defect distributions in In0.2Ga0.8As/GaAs multiple quantum wells grown on prepatterned GaAs

The defect distribution in a highly strained Ine,,C$,sAs/GaAs multiple-quantum-well (MQW) structure grown on a patterned GaAs substrate is examined with cathodoluminescence imaging and spectroscopy in the near infrared. By spatially correlating the luminescence arising from the MQW exciton recombination (A-950 nm) with the longer wavelength ( 1000 6 jls 1200 run) luminescence arising from the defect-induced recombination, we demonstrate that it is possible to determine the regions of highest film quality in both the mesa and valley regions. The present approach enables a judicious determination of the optimal regions to be used for active pixels in InGaAs/GaAs spatial light modulators.