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 InGaAsQDs 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 onQDs 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{sub}0.4Ga{sub}0.6As. The 3 layer QDs with 5 nm GaAs spacers showeda 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 topassivation of defect levels or nonradiation recombination centers by atomic hydrogen.0
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