Carrier thermalization and activation within self-assembled InAs/AlAs quantum dot states

The carrier transfer and activation processes among lateral coupled InAs/AlAs quantum dots (QDs) are investigated based on the analysis of excitation power and temperature dependence of photoluminescence. An unusual red-shift of ground-state emissions, accompanied by a shrinkage of its line width, with increasing power density, is observed. It is explained by scattering and tunnelling of carriers, which result in a preferential capture of carriers into lateral coupled QDs and recombination from the lowest energy levels. The temperature-induced red-shift of the photon emissions from ground and excited states are attributed to the thermal activation and redistribution among these QD states.