Lateral-coupling-induced modification of density of states and exciton dynamics in high-density ordered In0.4Ga0.6As/GaAs(311)B quantum dot arrays

We investigate, by photoluminescence excitation (PLE) measurements, the modification of density of states and exciton dynamics in a high-density ordered In0.4Ga0.6As/GaAs(311)B quantum dot (QD) array. It was observed that the PLE spectrum exhibited some remarkable features that were completely different from those found in isolated or weakly coupled QD arrays. The increase in exciton coherence length by strong lateral coupling is responsible for the change of the PLE spectrum. In addition, the effect of exciton-phonon scattering on exciton dynamics was studied by temperature-dependent time-resolved photoluminescence (TRPL) measurements. It was found that the exciton lifetimes near the mobility edge were significantly modified with increasing exciton-phonon scattering, leading to the broadening of the mobility edge.