Asymmetric correlation function describing the positional ordering of liquid-phase-epitaxySi–Genanoscale islands

Abstract

Liquid-phase-epitaxy grown SiGe nanoscale islands on (001)Si form extended chains which are aligned along the ⟨100⟩ directions. The positional ordering within the island chains was studied by x-ray diffuse scattering. The results can be interpreted by a short-range order model. The corresponding correlation function exhibits an asymmetric peak profile. The asymmetry leads to nonequidistantly spaced satellite peaks that disperse outward slightly with increasing lateral momentum transfer. The observed asymmetric island-island correlation is caused by the successive growth of the islands within a chain, while the new island position is influenced by depletion of the wetting layer around the island.