Observation of excited (bi-)exciton and multi-exciton features in locally homogeneous quantum dots

We investigate micro-photoluminescence spectra of arrays of locally homogeneous quantum dots (QDs). Our spectra indicate that the QDs exhibit excellent homogeneity in size on a length scale extending up to several microns. Using a Hartree–Fock based calculation including Coulomb and exchange energies, the observed spectra can be assigned to excitonic and multi-excitonic transitions, including excited exciton and excited bi-exciton transitions. We explain the strong excited-state recombinations due to the existence of a phonon bottleneck in our strain-free QD-arrays.