Low density GaAs/AlGaAs quantum dots grown by modified droplet epitaxy.

Low temperature photoluminescence spectroscopy is used to analyze the effects of the Ga coverage and of the postgrowth thermal annealing on the electronic properties of low density (≈1×109cm-2) self-assembled GaAs/AlGaAs quantum dots (QDs) grown by modified droplet epitaxy (MDE). We demonstrate that with the MDE method it is possible to obtain low density and high efficiency QD samples with high photoluminescence efficiency. Large modifications of the photoluminescence band, which depend on Ga coverage and thermal annealing, are found and quantitatively interpreted by means of a simple model based on the Al-Ga interdiffusion. [ABSTRACT FROM AUTHOR]