Suppressed bimodal size distribution of InAs quantum dots grown with an As 2 source using molecular beam epitaxy

We demonstrate the suppressed bimodal size distribution of InAs quantum dots (QDs) grown with an As 2 source using molecular beam epitaxy. QDs grown with an As 2 source have single mode photoluminescence (PL) spectra, whereas QDs grown with an As 4 source have bimodal spectra. The PL intensities of QDs grown with an As 2 source are higher than those grown with an As 4 source. The density of QDs grown with an As 2 source decreases at high As pressure, whereas the density of As 4 grown QDs increases with As pressure. These results indicate that the surface migration of In atoms is enhanced at a higher As 2 pressure, resulting in improved optical properties. The enhanced surface migration is thought to be due to the stable As-As dimer structures under an As 2 source.