Molecular Dynamics Simulation Of Beam Deposition Of Low-Energy (10-100 Ev) Si Atoms On The Si(111) Surface

Abstract

The deposition of low energy (10-100 eV) silicon atoms onto an unreconstructed (111) silicon surface has been studied using molecular dynamics techniques and an accurate empirical potential describing the covalent Si-Si bonding. 10 eV silicon atoms were directed normal and at 60° angles to a silicon (111) substrate. The resulting atomic trajectories and substrate response were studied to determine the energy loss mechanism resulting in capture and the local lattice excitation near, and subsequent diffusion of excess vibrational energy away from, the irridact point. More glancing angles of incidence (5°-30°) ) were studied for beam energies of 20-100 eV. In general, incident atoms are either quickly adsorbed or scatter from the surface in this energy range. However, for angles less than a critical value a new phenomenon of 'surface channeling' is observed. In 'surface channeling', the trajectory of the incoming particle is steered by short-range repulsive and long-range attractive interactions with the sur-face atoms parallel to, and roughly 2 A above, the surface of the substrate. Ranges of thousands of angstroms of travel along the surface can occur before the particle ultimately undergoes adsorption into a single site. These surface channeling trajectories as well as the local excitation provided by adsorption of energetic incident atoms offer considerable promise for precision control of the beam-induced growth of non-equilibrium semiconductor structures.