Imaging studies of strained InGaAsP/InP heterostructures by photoluminescence microscopy

Strained In/sub 1-x/Ga/sub x/As/sub y/P/sub 1-y//InP single quantum wells grown by low-pressure metal-organic vapor phase epitaxy were investigated by photoluminescence microscopy imaging (PLM), photoluminescence spectroscopy, X-ray diffraction and atomic force microscopy techniques. PLM images of strained structures revealed the presence of a large number of non-radiative centers (dark spots). The dark spot density was dependent on tensile strain magnitude, barrier material and cap layer thickness. PLM images of highly tensile and compressive strained quaternary layers grown with the same structure exhibited quite different relaxation mechanisms.