Atomistic simulation of silicon beam deposition.

Abstract

The mechanisms controlling low-energy (10--100 eV) beam deposition of silicon onto a relaxed (111) silicon substrate have been studied using a molecular-dynamics technique. The atomic interaction was modeled using a many-body empirical potential so that the effects of the covalent Si---Si bonding could be accurately included. 10-eV silicon atoms with near-perpendicular incidence were studied to determine the energy-loss mechanism resulting in capture and subsequent difffusion of excess vibrational energy away from the impact point. Shallower angles of incidence (5\ifmmode^\circ\else\textdegree\fi{}--30\ifmmode^\circ\else\textdegree\fi{}) were studied for beam energies of 20--100 eV. For incidence angles less than an energy- and orientation-dependent critical value, a new phenomenon of ''surface channeling'' is observed, in which the trajectory of the incoming particle is steered parallel to, and roughly 2 A\r{} above, the surface of the substrate by inelastic interaction with the surface atoms. The rate of energy loss in surface channeling trajectories is very slow, so that ranges of thousands of angstroms along the surface are possible. The phenomena observed in low-energy beam deposition offer considerable promise for precision control of the growth of nonequilibrium semiconductor structures.