Modification in the structural and optical characteristics of InAs quantum dots by manipulating the strain distribution

Abstract

We report the structural and optical properties of InAs quantum dots (QDs) on GaAs formed by using a modified self-assembled method (MSAM) adopting periodical arsenic interruption. From the atomic force microscopy images, the densities of the InAs QDs and large clusters grown by the conventional self-assembled mode (CSAM) were 7.3 × 1010 /cm2 and 1.9 × 109 /cm2, respectively. However, the density for the MSAM QD sample was significantly increased to 9.5 × 1010 /cm2, and no large clusters were observed at all. Also, the size distribution for the MSAM InAs QDs was improved to 8.9% from that for the CSAM QDs with 13.5%. The improvement in the structural properties of the MSAM InAs QDs can be explained by the modulation in the distribution of the strain field controlled by the growth kinetics of indium migration. Compared to that of the CSAM QDs, the photoluminescence (PL) peak for the MSAM QD sample was red-shifted, and the intensity was enhanced by more than 2.2 times. The PL decay profiles corresponding to the carrier lifetimes of InAs QDs are also discussed in terms of the variations in the structural properties.