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.