Size-dependence of anisotropic exchange interaction in InAs/GaAs quantum dots

Abstract

A comprehensive study of the exchange interaction between charge carriers in self-organized InAs/GaAs quantum dots is presented. Single quantum-dot cathodoluminescence spectra of quantum dots of different sizes are analyzed. Special attention is paid to the energetic structure of the charged excited exciton (hot trion). A varying degree of intermixing within the hot trion states leads to varying degrees of polarization of the corresponding emission lines. The emission characteristics change from circularly polarized for small quantum dots to elliptically polarized for large quantum dots. The findings are explained by a change of magnitude of the anisotropic exchange interaction and compared to the related effect of fine-structure splitting in the neutral exciton and biexciton emission.Comment: 4 pages, 3 figures, to be published in phys. stat. sol (b), proceedings of the QD2006, May 1-5 2006, Chamonix-Mont-Blanc, Franc