Magneto-optical study of thermally annealed InAs-InGaAs-GaAs self assembled quantum dots

We report a magneto-optical study of InAs-InGaAs-GaAs self-assembled quantum dots (QDs) subjected to post-growth thermal annealing at different temperatures. At low temperatures annealing strongly affects the bimodal distribution of QDs, at higher temperatures a strong blue shift of the emission occurs. Magneto-photoluminescence reveals that the annealing increases the QD size, with a larger effect occurring along the growth axis, and decreases the carrier effective masses. The main contribution to the blue shift is deduced to be an increase in the average Ga composition of the QDs. The inadvertent annealing which occurs during the growth of the upper AlGaAs cladding layer in laser structures is also studied.