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

Photoluminescence (PL) spectra and time-resolved PL data from AlGaAs/GaAs s uperlattice structures containing thin InAs layers of about 1-3 monolayer g rown on semi-insulating (001)-oriented GaAs substrates at lowered temperatu res are studied. The size distribution of InAs quantum dots (QDs) among dif ferent families (modes) is controlled by variation of growth temperature an d/or growth interruption. We demonstrate the stabilization of the PL magnit ude caused by strong coupling between different modes and the full width at half maximum of "large size" QD modes within a certain temperature interva l (50-150 K) due to feeding of the radiative transitions from nonradiative decay and carrier transfer arising from decaying excitonic states of the sm all 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 intermo de tunneling are determined from time-resolved PL. (C) 2000 American Instit ute of Physics. [S0021- 8979(00)04824-6].