Structure character in small-carbon-cluster deposition on diamond surface

Experimentally, hydrogen-free diamond-like carbon (DLC) films were assembled by means of pulsed laser deposition (PLD), where energetic small-carbon-clusters were deposited on the substrate. In this paper, the chemisorption of energetic C-2 and C-10 clusters on diamond (001)-(2x1) surface was investigated by molecular dynamics simulation. The influence of cluster size and the impact energy on the structure character of the deposited clusters is mainly addressed. The impact energy was varied from a few tens eV to 100 eV. The chernisorption of C-10 was found to occur only when its incident energy is above a threshold value (E-th). While, the C-2 cluster was easily to adsorb on the surface even at much lower incident energy. With increasing the impact energy, the structures of the deposited C-2 and C-10 are different from the free clusters. Finally, the growth of films synthesized by energetic C-2 and C-10 clusters were simulated. The statistics indicate the C-2 cluster has high probability of adsorption and films assembled of C-2 present slightly higher SP3 fraction than that of C-10-films, especially at higher impact energy and lower substrate temperature. Our result supports the experimental findings. Moreover, the simulation underlines the deposition mechanism at atomic scale.