Effects of few-particle interaction on the atomiclike levels of a single strain-induced quantum dot

We investigate the effects of few-particle population of a single strain-in duced quantum dot by optical excitation. The low-power photoluminescence sp ectra consist of sharp lines with energy separation of a few meV, associate d to the formation of excitonic molecules in the single dot. With increasin g photoexcitation intensity, the population of higher states is observed; h owever, we also observe a clear intensity dependence of the transition ener gies, inconsistent with a simple filling of exciton levels. Based on a theo retical model for interacting electron-hole pairs in the dot, we obtain goo d agreement with experiment and show that exciton-exciton interactions cont rol the spectral changes as the number of pairs is increased.