Simultaneous observation of confined energy levels and multi-excitonic features in a quantum dot

Abstract: We study the photoluminescence properties of GaAs/AlGaAs QD arrays grown by MBE on a patterned GaAs (311) substrate. At low excitation density, we observe sharp (<100 meV) excitonic recombination features, due to both the ground state and the exited energy levels of the individual dots. The excited levels are occupied due to the phonon bottleneck and allow to determine the dot shape. At higher excitation density, distinct bi-excitonic and multi-excitonic features appear which show a strong non-linear behavior