Epitaxial growth of silicon: A molecular-dynamics simulation

We have studied the epitaxial growth of silicon using molecular-dynamics techniques. The model consists of a temperature-controlled Si(111) substrate, with the Si atoms projected towards the substrate as is done in the laboratory. The atoms interact via a potential developed by Stillinger and Weber to simulate the bulk properties of Si. We find that at low substrate temperatures the growth is not well ordered; this is in accordance with experimental observation. It is precisely the opposite of what occurs in spherically symmetric potentials that were used to simulate the growth of metallic films. At higher substrate temperatures the growth is into properly stacked, crystalline Si layers. In contrast to the growth of metals (spherically symmetric potentials), the atomic mobility on the growing surface and the thermal conductivity of the system are much lower for Si; the results of this simulation and those of our previous work are in agreement with experimental observations showing, as expected, that a major determining factor in epitaxial growth of films is the nature of the interaction potential.