The radiative lifetime of charged excitons in a single self-assembled quantum dot

The small physical size of self assembled quantum dots gives rise to pronounced Coulomb interactions within the dots. By studying different excitons in the same quantum dot we show that the Coulomb interactions significantly alter the radiative recombination lifetime. The lifetime changes are larger upon charging from the neutral exciton to the positively charged exciton than from charging from the neutral exciton to the negatively charged exciton. This is attributed to a frozen electron wavefunction and a non-frozen hole wavefunction, leading to a non-perturbative hole-hole Coulomb interaction. Theoretical calculations based on a path integral quantum Monte-Carlo approach show good agreement between experiment and theory.