Self-organized InSb quantum dots grown by atomic layer molecular beam epitaxy

摘要

Insb self-organized quantum dots grown on InP substrates by Atomic Layer Molecular Beam Epitaxy have been characterized by STransmission Electron Microscopy in order to assess their morphology and the relaxiation mechanisms. Raman spectra have also been recorded to confirm the strain state of the dots. High energy electron diffraction control during dots growth idicates a transition from 2D to 3D gowth mode beyond an equivalent amount of 1.4 monolayers of InSb. Dots have, in general, a good crystalline quality as well as homogensous surface distribution and regulr dimension, but a high anisotropy between [110] and [110] directions in size. An anisotropic corrugation of substrate surface is also found being its valleys and hillocks parallel to dots elongation. High resolution images show that dots are faceted by a top (001) plane and {111}, {113} and {114} lateral sides. Strain is effectively relieved by a dislocation array placed at the interface.