Pressure effects on neutral and charged excitons in self-assembled (In,Ga)As/GaAs quantum dots

摘要

By combining an atomistic pseudopotential method with the configuration-interaction approach, we predict the pressure dependence of the binding energies of neutral and charged excitons: X~0 (neutral monoexciton), X~-and X~+ (charged trions), and XX~0 (biexciton) in lens-shaped, self-assembled In_(0.6)Ga~(0.4)As/GaAs quantum dots. We predict that (ⅰ) with applied pressure the binding energy of X~0 and X~+ increases and that of X~- decreases, whereas the binding energy of XX~0 is nearly pressure independent, (ⅱ) Correlations have a small effect in the binding energy of X~0, whereas they largely determine the binding energy of X~-, X~+, and XX~0, (ⅲ) Correlations depend weakly on pressure; thus, the pressure dependence of the binding energies can be understood within the Hartree-Fock approximation and it is controlled by the pressure dependence of the direct Coulomb integrals J. Our results in (ⅰ) can thus be explained by noting that holes are more localized than electrons, so the Coulomb energies obey J~((hh)) > J~((eh)) > J~((ee)).