Influence of atom diffusion parameters on Ge nano-island orientation on Si(111) at initial nucleation stage

The reasons for three-bilayer Ge nano-island nucleation on a Si(111) surface at low deposition rates, at the initial stages of wetting layer formation, were investigated. The simulation of Ge epitaxial growth on an atomically clean and flat Si(111) surface was carried out by a 3D Monte Carlo model. The influence of different diffusion parameters on island orientation was investigated. A new hypothesis, on the basis of simulations and literature analysis, provides an explanation for Ge-island height limitation by three-bilayer height at the initial nucleation stages on the Si(111) surface.