Kinetic lattice Monte Carlo simulations of germanium epitaxial growth on the silicon (100) surface incorporating Si-Ge exchange

We present kinetic lattice Monte Carlo simulations of Ge deposition onto the Si (100) surface. In addition to the anisotropy brought on by surface reconstruction, we take into account the effects of the exchange of Ge with Si atoms in the substrate and how this affects the interface between the materials. For this, we consider two possible mechanisms: (1) a dimer exchange mechanism whereby Ge-Ge dimers on the surface become intermixed with substrate Si atoms, and (2), in the case of more than one monolayer of coverage, the exchange of Ge atoms below the surface to relieve misfit strain. The former mechanism results in only a small percentage of Si atoms being elevated to the first adsorbed monolayer, which settle at random locations on the surface. Beyond one monolayer, the latter mechanism strongly dominates what occurs and the reconstruction leads to some segregation of the Si and Ge atoms below the surface.