Narrowing of ground energy level distribution in an array of InAs/AlAs QDs by post grown annealing

The effect of a post growth annealing on the structure and photoluminescence (PL) of InAs/AlAs quantum dots has been studied. The annealing at temperatures below 650 C does not effect the PL spectrum, while a blue shift as large as 400 meV and a significant narrowing of the QD PL band are observed at annealing temperatures in the range 650-950 C. Transmission electron microscopy demonstrates that the changes in the PL spectrum are accompanied by an increase in the average QD size and its dispersion. The blue shift and narrowing are explained by a shift of the QD energy levels towards the level of a shallow quantum well as a result of interdiffusion. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)