We fabricated GaAs/AlGaAs quantum dots by droplet epitaxy method, and
obtained the geometries of the dots from scanning transmission electron
microscopy data. Post-thermal annealing is essential for the optical activation
of quantum dots grown by droplet epitaxy. We investigated the emission energy
shifts of the dots and underlying superlattice by post-thermal annealing with
photoluminescence and cathodoluminescence measurements, and specified the
emissions from the dots by selectively etching the structure down to a lower
layer of quantum dots. We studied the influences of the degree of annealing on
the optical properties of the dots from the peak shifts of the superlattice,
which has the same composition as the dots, since the superlattice has uniform
and well-defined geometry. Theoretical analysis provided the diffusion length
dependence of the peak shifts of the emission spectra
