Growth and optical properties of ZnTe quantum dots on ZnMgSe by molecular beam epitaxy

Self-assembled type-II ZnTe quantum dots (QDs) were grown on GaAs (0 0 1) substrates with Zn1−xMgxSe (x=0.24 and 0.52) buffer layers by molecular beam epitaxy. The optical properties of ZnTe QDs were investigated by low-temperature photoluminescence (PL) and time-resolved PL. An abrupt variation of the PL peak energy with coverage implies the existence of wetting layer of 3.2 MLs and 4.0 MLs for the Mg concentration x=0.24 and 0.52, respectively. The thickness of wetting layer is larger than that of ZnTe QDs grown on ZnSe buffer layers because the strain between ZnTe and Zn1−xMgxSe is smaller. The non-mono-exponential decay profiles reflect the processes of carrier transfer and recapture. The Kohlrausch׳s stretching exponential well fits the decay profiles of ZnTe/Zn1−xMgxSe QDs.