Carbon atoms and carbon dimers (C2) were known to be the main projectiles in the deposition of diamond-like carbon films. The adsorption and diffusion of C adatoms and ad-dimers on the fully relaxed Si(001)-(2x1) surface were studied using a combination of molecular dynamics and Monte Carlo simulation. The adsorption sites of C and C2 on the surface, and the potential barriers between these sites, were determined using the semi-empirical many-body Brenner & Tersoff potential. Their hopping rates were estimated and their pathways were traced. It was found that the diffusion of both C and C2 was strongly anisotropic. The C adatom could diffuse a long distance on the surface while adsorbed C2 was more likely to be confined to a local region. It was expected that smoother films would be formed on a Si(001) surface using single C atoms as projectiles at moderate temperatures. For C2, the films grew as two-dimensional islands. A relatively higher kinetic energy of the projectile was needed to grow diamond-like carbon films of higher quality.

Surface Diffusion of Carbon Atom and Carbon Dimer on Si(001) Surface. J.Zhu, Z.Y.Pan, Y.X.Wang, Q.Wei, L.K.Zang, L.Zhou, T.J.Liu, X.M.Jiang: Applied Surface Science, 2007, 253[10], 4586-92