Post-growth annealing effects of In0.5Ga0.5As quantum dots grown by heterogeneous droplet epitaxy

Post-growth rapid thermal annealing modifies the structural and the optical properties of the In0.5Ga0.5As quantum dots grown on GaAs substrates by using heterogeneous droplet epitaxy. It is found that at annealing temperatures up to 750 ◦C, a significant decrease in the intersublevel (E01 = E1 − E0) from 55 to 23.7 meV occurs together with about a 62-meV blueshift. Also, we observe a decrease in the activation energy of about 200 meV. These results are explained by interdiffusion of In-Ga atoms at the interface between the QD and the GaAs barrier, which changes the composition of the QDs.