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 beam epitaxy was demonstrated. Unlike the stress-driven transition of the three-dimensional growth mode in the lattice-mismatched system, the limited migration of Ga droplets on the AlGaAs layer grown at low substrate temperature was exploited to give rise to the formation of three-dimensional GaAs islands. The resulting GaAs dots show crater-like features having {111} facets. In micro-photoluminescence measurements of the buried structures, the emission spectra were clearly observed, and the sharp lines of the spectra might be considered as the exciton emissions from individual dots with various sizes.