Submonolayer growth study using a solid-on-solid model for 2 × 1 reconstructed surfaces of diamond-like lattices

We have developed a simple cubic solid-on-solid (SOS) model of growth that captures many of the features of 2 × 1 reconstructed surfaces. Energetics in the model is based on bond-counting and the tendency to form dimer rows is controlled by a reconstruction energy parameter δ. We examine the dependence of the shapes and sizes of islands formed at submonolayer coverage on the parameter δ. The aspect ratio distribution of islands indicates a transition from two-dimensional to one-dimensional growth as δ is increased. At coverages below 0.2 ML, the islands are mostly made of dimer chains with aspect ratios as large as 14. On annealing the system, the islands coalesce into larger islands with a much smaller aspect ratio of approximately 3. Through extensive simulations, we have found a set of parameters that reproduces the known experimental results on submonolayer growth on Si(001) in Molecular Beam Epitaxy(MBE). These results include island size and shape distribution and their dependence on temperature. This model can be used to study heteroepitaxial thin film growth on reconstructed surfaces.