Enhanced band-gap blueshift due to group V intermixing in InGaAsP multiple quantum well laser structures induced by low temperature grown InP

Photoluminescence and cross-sectional transmission electron microscopy, combined with x-ray compositional analysis, have been used to study quantum well intermixing in an InGaAsP quantum well laser structure. Quantum well intermixing is induced by capping the samples with a layer of InP grown at low temperature (300 °C) and subjecting them to rapid thermal anneal treatments in the temperature range 600–800 °C. The presence of the low temperature InP layer, which contains an abundance of nonequilibrium point defects, significantly enhances the intermixing on annealing, producing a large band-gap blueshift. The microscopy results show good broadening with smeared interfaces, and the compositional analysis suggests this can be attributed to the intermixing of group V atoms.