Abstract
We report on the electronic coupling effect on carrier dynamics in InAs/GaAs vertically stacked quantum dot (QD) layers. For this purpose, both pico-second and continuous-wave excitation techniques have been used. We show that for large numbers of QD deposition cycles (≥10 planes), lateral coupling effects between the neighbouring QDs of the same InAs layer influence remarkably the electronic structure. Lateral coupling of vertically-aligned QDs results in the appearance of a new photoluminescence (PL) band. This new PL line is associated to the radiative recombination of excitons via electronic states induced by laterally coupled QDs (LCQDs). In the 20-layer sample, this effect is shining by dominating the PL spectrum. A strong increase of the radiative lifetime has been obtained for the laterally coupled QDs. Moreover, strong temperature and power excitation dependencies of the PL decay time have been found.