Self-assembled InAs quantum dots (QDs) grown on Sb/GaAs buffer layers by molecular beam epitaxy were investigated to achieve high-density and high-uniformity QDs. The density of InAs QDs on Sb/GaAs layers was markedly higher than that of InAs QDs on conventional GaAs layers. The high-density nucleation of three-dimensional (3D) InAs islands was attributed to the formation of two-dimensional (2D) wirelike structures prior to 3D islanding. QD density was controlled from 3 Â 10 10 to 1 Â 10 11 cm À2 by changing Sb supply amount. In addition, the density of very large dots due to coalescence increased with increasing Sb supply amount. On Sb (0.6 atomic layers)/GaAs buffer layers, we obtained high-density and high-quality InAs QDs, which revealed a narrow photoluminescence linewidth of about 30 -35 meV.
InAs quantum dots (QDs) were grown on GaAsSb∕GaAs(001) buffer layers by molecular beam epitaxy using a Stranski-Krastanov mode. A high QD density of about 1×1011 cm−2 was obtained for an Sb flux ratio of more than 0.14. In the case of high-density QD growth on the GaAsSb layers, many nanoholes were observed on the surface and located beside the QDs. In addition, one-dimensional QD chains were formed near nanogrooves and step edges. As the InAs growth proceeded, an in-plane arrangement of the InAs QDs was partially formed along ⟨010⟩ directions. It is considered that the in-plane arrangement of the QDs originates from the QD chains and the nanogrooves, aligned along ⟨010⟩ step edges. From transmission electron microscopy and photoluminescence measurements, it was found that the high-density InAs QDs on the GaAsSb buffer layer reveal high crystal quality.
The self-formation of InAs quantum-dot chains (QDCs) was demonstrated on GaAs/InGaAs/GaAs(001) layers by molecular beam epitaxy (MBE). In the MBE growth of a GaAs layer on a corrugated InGaAs/GaAs buffer layer, mesa-stripe structures with the {211}A side wall were spontaneously formed along the [1 1 10] direction. InAs QDCs were formed on the GaAs mesa stripes along the [1 1 10] direction. In particular, uniform InAs QDCs were fabricated on the vicinal GaAs(001) substrate, misoriented toward the [110] direction. The self-formation of QDCs was attributed to the misfit dislocation and step structure.
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