Radiative lifetimes of spatially indirect excitons in type-II InAs/GaAsSb quantum dots

InAs/GaAsSb quantum dots (QDs) are recognized for their exceptional emission in the near-infrared spectrum, typically ranging from 1.28 to 1.6 $\mu m$. These nanostructures hold significant promise for applications in fiber-optic communication, medical imaging, and environmental sensing systems. In this work, we theoretically investigated the effect of antimony composition on the emission properties of type-II InAs QDs embedded in GaAsSb barriers. First, we focus on the dependence of strain induced by lattice mismatch on charge carrier confinement profiles in InAs/GaAs${}_{1-x}$Sb${}_x$/GaAs heterostructures ( $x=0.18$, 0.24, and 0.28). Second, we discuss the influence of confinement potentials on the spatial distribution of charge carriers. We then calculate the electronic states as a function of antimony composition using an exact numerical diagonalization method. The ground-state exciton binding energy is estimated to be low, around ($\simeq$ 4 meV), for type-II QDs. Finally, the predicted values of the ground-state excitonic transition energy and the corresponding radiative lifetime of spatially indirect excitons structures are generally consistent with experimental results.