Molecular-dynamics simulation of molecular-beam epitaxial growth of the silicon (100) surface

Abstract

We have simulated the growth of a Si(100) surface by deposition of silicon atoms from a molecular beam. A molecular-dynamics technique is employed where the equations of motion of 256 bulk particles and up to 256 additional adsorbed surface particles are solved exactly. We have used the Stillinger-Weber two- and three-body interaction potential to compute the forces between silicon atoms. Temperature and surface-reconstruction effects on the growth rate and surface morphology are studied. Bulk samples of Si are prepared at two temperatures, $T_{\mathrm{low}=(1/8\mathrm{}{T}_{\mathrm{melt}}}$ and $T_{\mathrm{high}=(2/3\mathrm{}{T}_{\mathrm{melt}}}$, and after a period of equilibration the beam is directed at the (100) surface. Prior to the deposition of new silicon and after the truncated bulk has come into equilibrium, the 2×1 dimer reconstruction is seen to have occurred. We observe the growth of an amorphous overlayer and the persistence of surface reconstruction at $T_{\mathrm{low}}$. For the $T_{\mathrm{high}}$ case the growth is characterized by the formation of more ordered epilayers and the disappearance of the 2×1 surface reconstruction. These results are in qualitative agreement with experimental studies of the molecular-beam epitaxial (MBE) growth of the Si(100) surface.