Exciton fine structure splitting in self-assembled semiconductor quantum dots: Intrinsic and extrinsic effects

We investigate the excitonic fine structure splitting (FSS) in InGaAs/GaAs and GaAs/AlGaAs quantum dots (QDs) of different shapes and sizes using an atomistic pseudopotential approach [1,2]. We consider intrinsic effects originating from the atomistic symmetry of the structure. We highlight the effects of the growth direction and the repercussions it has on the point group symmetry and the FSS. We give predictions for the cases where the semiconductor alloy has a certain degree of atomic order, and for the case, where the QDs are influenced by charged point defects. These effects are contrasted to the extrinsic effect of applied stress.\\ \noindent [1] R. Singh and G. Bester, {\it Lower bound for the excitonic fine structure splitting in self-assembled quantum dots.} Phys. Rev. Lett. {\bf 104}, 196803 (2010).\\ \noindent [2] R. Singh and G. Bester, {\it Nanowire Quantum Dots as an Ideal Source of Entangled Photon Pairs.} Phys. Rev. Lett. {\bf 103}, 063601 (2009).