MOLECULAR-DYNAMICS INVESTIGATION OF THE MBE GROWTH OF SI ON SI(110)

The crystal growth of Si{110} by deposition of single Si atoms from the gas phase is modeled by molecular dynamics simulations using an empirical potential. The bulk terminated Si{110} surface has easily accessible epitaxial sites for growth. However, we find the most stable adsorption site on the clean surface is a threefold coordinated site and not the epitaxial site. The adsorbed atoms in the threefold coordinated sites tend to destabilize atoms in the original surface layer. This causes interlayer diffusion in which the destabilized surface atoms move up into the growing layers. We find that even though the formed crystalline structure is perfect with no vacancies, the atoms from the original surface layer move to the top of four added layers and as much as one third of the original surface atoms migrate into the forming layers. Simulations also reveal that there is a chain mechanism whereby atoms in non-epitaxial sites are pushed into epitaxial positions when a row is nearly full.