  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.
