Improvement of the optical property and uniformity of self-assembled InAs/InGaAs quantum dots by layer-by-layer temperature and substrate rotation

The influence of layer-by-layer temperature and substrate rotation on the optical property and uniformity of self-assembled InAs/In_0.2Ga_0.8As/GaAs quantum dots (QDs) gown with an As₂ source was investigated. An improvement in the optical property of QDs was obtained by the precise control and optimization of growth temperature utilized for each layer, i.e., InAs QDs, InGaAs quantum wells, GaAs barriers and AlGaAs layers, respectively. By using a substrate rotation, the QD density increased from ∼1.4×10¹⁰ to ∼3.2×10¹⁰ cm^-2 and its size also slightly increased, indicating a good quality of QDs. It is found that the use of an appropriate substrate rotation during growth improves the room-temperature (RT) optical property and uniformity of QDs across the wafer. For the QD sample with a substrate rotation of 6 rpm, the RT photoluminescence (PL) intensity is much higher and the standard deviation of RT-PL full-width at half-maximum is decreased by 35% compared to that grown without substrate rotation.