Thin film deposition of tetrahedral amorphous carbon: a molecular dynamics study

Molecular dynamics simulations of carbon thin film deposition are performed using the Environment Dependent Interaction Potential. Films deposited with carbon beams in the range 1-100 eV reproduce the energy dependence of the biaxial stress, density and tetrahedral bonding fraction observed experimentally. The transition from low-density, graphite-like amorphous carbon to the high-density tetrahedral phase occurs at an energy at which impacting ions do not penetrate the surface of the film. This result is incompatible with the generally accepted subplantation explanation for the diamond-like properties, and a new model of energetic burial is deduced from the simulations. Radial distribution functions compare well with experiment, and represent a significant improvement over Tersoff and Brenner simulations which contain unphysical distances.