Experimental and theoretical study of strain-induced AlGaAs/GaAs quantum dots using a self-organized GaSb island as a stressor

Low-temperature photoluminescence (PL) measurement and strain distribution calculation have been performed on strain-induced AlGaAs/GaAs quantum dots (QD) using self-organized GaSb islands on a GaAs surface as stressors (the lattice mismatch between GaSb and GaAs is 7.8%). Since lattice mismatch plays a crucial role in fabricating this strain-induced QD, the article compared self-organized GaSb island stressor and self-organized InP island stressor. Both of these self-organized islands are formed on a GaAs surface (the lattice mismatch between InP and GaAs is 3.8%). This article indicates that it is not an effective way to increase the strain effect by choosing a stressor with higher lattice mismatch. It also shows that higher lattice mismatch results in smaller coherent self-organized islands. This weakens the strain effect. The strain effect can be enhanced by decreasing a top layer thickness under the stressor, but the enhanced surface state due to the strain also decreases the PL emission intensity greatly. Based on this study, this article puts forward a suggestion on fabricating this strain-induced QD. In addition, our strain calculation predicts that the strain effect could be enhanced by thickening the wetting layer, which may be realized by lowering the growth temperature of the stressor.