Molecular beam epitaxy growth of InSb/GaAs quantum nanostructures

InSb/GaAs nanostructures grown by solid-source molecular beam epitaxy are investigated in this work. Three-dimensional dot-like InSb nanostructures are obtained by self-assembled growth at relatively low growth temperatures (250-300 °C) with slow InSb growth rate. Nanostructure base is typically elongated. Facet analysis of the free-standing InSb nanostructure grown at 250 °C shows that each nanostructure has flat top (001) surface while side facets are along <11n> directions. In contrast, InSb nanostructures grown at higher temperature show rather smooth surfaces. Analysis of their size distributions shows that the size inhomogeneity increases with the growth temperature. Moreover, Raman spectroscopy reveals both InSb-related peaks at 181 and 189 cm−1 and GaAs-related peaks at 268 and 293 cm−1. Raman spectroscopy with different excitation wavelengths is applied to probe residual strain in subsurface GaAs layer.