Pressure effects on neutral and charged excitons in self-assembled InGaAs/GaAs quantum dots

摘要

By combining an atomistic pseudopotential method with the configurationinteraction approach, we predict the pressure dependence of the bindingenergies 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 thatof $X^-$ decreases, whereas the binding energy of $XX^0$ is nearly pressureindependent. (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 pressuredependence of the binding energies can be understood within the Hartree-Fockapproximation and it is controlled by the pressure dependence of the directCoulomb integrals $J$. Our results in (i) can thus be explained by noting thatholes are more localized than electrons, so the Coulomb energies obey$J^{(hh)}>J^{(eh)}>J^{(ee)}$.