Fabrication of self-assembled GaAs/AlGaAs quantum dots by low-temperature droplet epitaxy

The fabrication of nanometer-scale GaAs dots on AlGaAs layer by molecular b eam epitaxy was demonstrated. Unlike the stress-driven transition of the th ree-dimensional growth mode in the lattice-mismatched system, the limited m igration of Ga droplets on the AlGaAs layer grown at low substrate temperat ure was exploited to give rise to the formation of three-dimensional GaAs i slands. The resulting GaAs dots show crater-like features having {111} face ts. In micro-photoluminescence measurements of the buried structures, the e mission spectra were clearly observed, and the sharp lines of the spectra m ight be considered as the exciton emissions from individual dots with vario us sizes.