Tuning of the valence band mixing of excitons confined in GaAs/AlGaAs quantum dots via piezoelectric-induced anisotropic strain

This work presents an experimental method to tune the degree of heavy-hole (HH) and light-hole (LH) mixing of the ground state of quantum dots (QDs). A ferroelectric crystal is used to apply reversible anisotropic biaxial stress to thin nanomembranes, containing GaAs/AlGaAs QDs. The stress-induced modification of the QD anisotropy leads to a change of the relative intensity of the two emission lines produced by the recombination of neutral bright excitonic states. Such a change is ascribed to a variation of the degree of HH-LH mixing. At the same time the modified anisotropy produces a change of the excitonic fine structure splitting (FSS). Model calculations provide a qualitative insight into the relation between strain, HH-LH mixing, and the FSS in epitaxial GaAs/AlGaAs QDs.