Growth of ultrathin diamond-like carbon films by C60 cluster assembly: Molecular dynamics simulations

The deposition of C60 clusters to produce cluster-assembled ultrathin diamond-like carbon (DLC) films is investigated using the molecular dynamics (MD) simulations. The deposition dynamics, especially the fragmentation process of the C60 cluster are studied. The trajectory and instantaneous velocity of each atom in the cluster reveal a close relationship between cluster deposition and atom-by-atom deposition of DLC film. The atomistic structures, sp3 fractions, and radial distribution functions of DLC films are quantitatively studied. For relatively low energies (E < 20 eV/atom), the C60 structural features preserve partially. The cluster-assembled films show big cavities, non-uniform structures, and rough surfaces. For relatively high energies (E > 20 eV/atom), the films turn out to be structurally amorphous, densely-packed and sp3 dominated. A marked discrepancy is observed between the sp3 fraction of cluster and atom-by-atom deposited DLC films. The kinetic energy dissipation and the oblique incidences of freed atoms are the main reason for this discrepancy.