Molecular-dynamics simulation of amorphous and epitaxial Si film growth on Si(111)

Both amorphous and epitaxial crystalline Si films have been grown by deposition of Si-atom clusters on a Si(111) substrate with molecular-dynamics simulations utilizing two- and three-body interatomic Si potentials. The amorphous films were produced with deposition conditions that led to low surface diffusion. The a-Si films displayed voids, a 15--28 % lower density than c-Si, and coordination defects consisting only of undercoordinated atoms with no fivefold-coordinated atoms, in contrast to melt-quenched a-Si models. The epitaxial Si(111) growth was achieved under conditions of high surface diffusion consisting of a large initial cluster velocity and moderate substrate temperatures.