Carrier transfer in self-assembled coupled InAs/GaAs quantum dots

Abstract

Photoluminescence (PL) spectra and time-resolved PL data from AlGaAs/GaAs superlattice structures containing thin InAs layers of about 1–3 monolayer grown on semi-insulating (001)-oriented GaAs substrates at lowered temperatures are studied. The size distribution of InAs quantum dots (QDs) among different families (modes) is controlled by variation of growth temperature and/or growth interruption. We demonstrate the stabilization of the PL magnitude caused by strong coupling between different modes and the full width at half maximum of “large size” QD modes within a certain temperature interval (50–150 K) due to feeding of the radiative transitions from nonradiative decay and carrier transfer arising from decaying excitonic states of the small size QD modes. Strong competition between different channels of ground state relaxation leads to an oscillating dependence of the PL transient for the small size QD mode. Efficient inter- and intramode tunneling rules out “bottleneck restrictions” for the PL. The parameters of intra- and intermode tunneling are determined from time-resolved PL.