Unidirectional self-assembling of SiGe Stranski-Krastanow islands on Si(113)

Abstract

We report on a dedicated two-step liquid phase epitaxy (LPE) experiment yielding ensembles of SiGe∕Si(113) nanoscale islands with unidirectional ordering along the [1¯10] direction. Initial homoepitaxy of silicon on a polished Si(113) wafer from an indium solution at 930°C results in a highly regular pattern consisting of (111) and (116) facets. For the subsequent heteroepitaxy with SiGe the solvent has been exchanged for bismuth since it enables an LPE process at considerably lower temperatures around 590°C, and thus preserves the initial template which strictly enforces the linear self-assembling of SiGe islands. However, with respect to the initial grooves the established island–island correlation length perpendicular to them has been increased by a factor of about 1.6 indicating that not every groove acts as a nucleation place. This can be explained by finite element calculations on the three-dimensional deformation field which proves energetically favorable nucleation sites in the island vicinity within and infavorable places in adjacent rows.