SUBSTITUTIONAL CARBON IMPURITIES IN THIN SILICON FILMS - EQUILIBRIUM STRUCTURE AND PROPERTIES

We discuss a set of atomistic calculations of the structure of Si geom etries with substitutional carbon atoms, involving the (100) surface o r bulk features related to thin films grown; in the (100) direction. W e use both quantum mechanical density functional theory and empirical potential calculations at finite temperature and constant pressure to study the local structure, bonding characteristics and overall distrib ution of the carbon atoms in the host silicon lattice. These calculati ons reveal a strong nearest neighbor repulsion between substitutional carbon atoms, to the point where these atoms prefer to have fewer bond s than normally in order to avoid each other., This effect still holds for high temperatures and high carbon concentrations. As a result, bu lk ordering of the type observed in Si-Ge alloys is unlikely to occur. (C) 1998 American Vacuum Society.