Role of [formula omitted] surface reconstruction on Stranski–Krastanov growth illustrated using a modified solid-on-solid model

Abstract

We develop a modified solid-on-solid model for studying heteroepitaxial growth of Ge on a 2×1 reconstructed Si(001) surface. The model is implemented using lattice-based kinetic Monte Carlo simulations using an atomistic model of elasticity. Our simulations show that the films are grown via Stranski–Krastanov mode with about 2 film layers wetting the substrate below three-dimensional islands. The island shapes evolve from rectangular-based at low coverage(thin films) to square-based at higher coverage. Their size distribution changes from bimodal to unimodal at higher coverage, and subsequently the surface is covered by uniform-sized islands. For simulations performed at lower deposition flux, the shape transition is observed for lower coverage. Our results are consistent with experiments and emphasize the role of the 2×1 reconstruction of the underlying Si(001) surface on the observed behavior. This is the only atomistic model that has been shown to reproduce features of both submonolayer growth and the Stranski–Krastanov growth transition at higher coverage.