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

TL;DR

This study predicts how pressure influences the binding energies of various excitons in self-assembled InGaAs/GaAs quantum dots using atomistic and configuration interaction methods, revealing different pressure dependencies for each exciton type.

Contribution

It provides a detailed theoretical prediction of pressure effects on exciton binding energies, highlighting the roles of correlations and Coulomb interactions in these quantum dots.

Findings

Binding energy of X^0 and X^+ increases with pressure.

Binding energy of X^- decreases with pressure.

Binding energy of biexciton XX^0 is nearly pressure independent.

Abstract

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 $J^{(hh)}>J^{(eh)}>J^{(ee)}$.