Quantitative compositional analysis of quantum well intermixing using a low temperature MBE-grown InP cap layer

摘要

Quantitative compositional evolution is determined for quantum well intermixing (QWI) between In-GaAsP quantum wells (QW) confined by InGaAsP quaternary barriers driven by a low temperature (300℃) MBE grown phosphorous-rich InP cap layer (LT-InP). Presence of the LT-InP cap layer results in a significant blue-shift in the QW photoluminescence (PL) peak during post-growth annealing and in reduction of the PL intensity. Cross-sectional transmission electron microscopy (XTEM) analysis reveals deterioration of the whole structure, with the formation of precipitates and broadening of QWs in the capped structures, whereas relatively small changes take place in the uncapped samples. Energy-dispersive X-ray spectroscopy (EDX) analysis shows that the P concentration in the QW for structures capped with LT-InP is double that of samples without the cap. The EDX data indicates increased P in all layers as the anneal temperature is increased while As precipitates also form.