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Free keywords:
indium compounds; III-V semiconductors; semiconductor quantum dots; semiconductor growth; molecular beam epitaxial growth; scanning tunnelling microscopy; wetting; crystal defects; scanning-tunneling-microscopy; nanostructure formation; surface; gaas; shape; reconstructions; GaAs(2511); morphology
Abstract:
InAs quantum dots (QDs) were prepared by molecular beam epitaxy on GaAs(-1-1-2)B substrates. Shape and size distribution of the QDs were investigated using in situ scanning tunneling microscopy as function of preparation temperature between 435 and 550 °C. The wetting layer is not flat but undulated in submicrometer scale in a similar way as the bare substrate. The atomic structure of the wetting layer is the same as found for the flat base of InAs QDs grown on GaAs(-1-1-3-)B substrates. The shape of the QDs is given by {110}, (-1-1-1)B, and {-1-4-3}B bounding facets and a round vicinal (00-1) region. Unexpectedly, the number density increases and the size distribution sharpens, when the growth temperature is increased from 435 to 470 °C, which is attributed to lattice defects incorporated into the QDs during growth at 435 °C.
