Structural and optical properties of multi-stack InAs/GaAsSb quantum dots with different Sb composition

The impact of the Sb composition on the structural and optical properties of ten-stack InAs/GaAsSb quantum dots (QDs) were investigated using transmission electron microscopy (TEM), high-resolution x-ray diffraction (XRD), and photoluminescence (PL). The TEM images demonstrate that the Sb composition affects the change in the QD density and morphology. From analysis of XRD reciprocal space maps (RSMs) of the (224) asymmetrical reflection, it is found that as the Sb composition increases the relaxation of the initial elastic stress of the GaAsSb increases up to 23 %. In addition, the Sb composition influences the interband optical transitions such as the PL peak redshift and carrier lifetimes.