Self-organized quantum dots grown on GaAs(311)B by atomic hydrogen-assisted molecular beam epitaxy

Abstract

We have investigated the growth mechanism of self-assembled InGaAs quantum dots (QDs) on GaAs(311)B substrates with molecular beam epitaxy. The V-shaped concave structures were observed on the surface after depositing GaAs buffer layer and InGaAs QDs layer by atomic force microscope. The density of the V-shaped concave structures decreased with decreasing growth rate, while the concave structures covered the surface and most of QDs were disappeared with annealing. The dependence of In content on QDs structure indicated that there was a difference in growth mechanism between InGaAs and InAs QDs. We have also investigated photoluminescence (PL) characteristics for stacked QDs of In 0.4Ga 0.6As. The 3 layer QDs with 5 nm GaAs spacers showed a PL intensity 4 times greater than that of single layer QDs. In addition, 3 layer QDs grown with atomic hydrogen irradiation showed a PL intensity 12 times greater as compared to 3 layer QDs grown without atomic H irradiation. This may be due to passivation of defect levels or nonradiation recombination centers by atomic hydrogen.