MOLECULAR-DYNAMICS STUDIES OF A-C-H FILM GROWTH BY ENERGETIC HYDROCARBON MOLECULE IMPACT

Classical molecular dynamics calculations were performed to study the deposition of thin hydrogenated carbon films. Hydrogen-covered diamond {111} and {001}-(2 x 1) surfaces were bombarded with energetic acetyl ene (C2H2) molecules at impact energies from 40 to 240 eV, Brenner's e mpirical hydrocarbon potential was used to model the atomic interactio ns. For single impacts, sputtering yields, as well as depth distributi ons far the deposited atoms. and for the changes in the coordinations of the carbon atoms, were computed. Carbon and hydrogen penetration pr obabilities are obtained which are in line with experimental results. Film growth was modelled for an 80 eV C2H2 beam and a diamond {111} su bstrate. A 4-fold coordinated amorphous carbon network is formed only in the immediate neighbourhood of the unperturbed substrate layers and only at low substrate temperatures (typically 100 K). This result see ms to be favoured by the projectile hydrogen atoms. (C) 1998 Elsevier Science S.A.