Atomic-scale modeling of the ion-beam-induced growth of amorphous carbon

The results of a detailed molecular-dynamics study of the growth of amorphous carbon (a-C) are reported. Carbon atoms with kinetic energies between 10 and 150 eV are deposited on a-C surface originating from bulk a-C. Earlier simulation results of an optimal energy window at 40--70 eV are confirmed. Additionally, it is found that the growth rate is at maximum at around 40 eV. At low implantation energies (Ebeam≈10 eV), the growth of amorphous carbon takes place on the surface. At higher energies, the growth proceeds increasingly in the subsurface region by global film expansion and single atom diffusion towards the surface. Scattering events (e.g., the deposited atom does not adsorb to the surface) at intermediate energies Ebeam≈100 eV result in a densification of the growing film. Moreover, at Ebeam≈150 eV, nonpermanent diamond formation is observed.