Simulations of C ₆₀ bombardment of Si, SiC, diamond and graphite

Molecular dynamics simulations of the 20-keV C ₆₀ bombardment at normal incidence of Si, SiC, diamond and graphite targets were performed. The unique feature of these targets is that strong covalent bonds can be formed between carbon atoms from the C ₆₀ projectile and atoms in the solid material. The mesoscale energy deposition footprint (MEDF) model is used to gain physical insight into how the sputtering yields depend on the substrate characteristics. A large proportion of the carbon atoms from the C ₆₀ projectile are implanted into the lattice structure of the target. The sputtering yield from SiC is ∼twice that from either diamond or Si and this can be explained by both the region of the energized cylindrical tract created by the impact and the number density. On graphite, the yield of sputtered atoms is negligible because the open lattice allows the cluster to deposit its energy deep within the solid. The simulations suggest that build up of carbon with a graphite-like structure would reduce any sputtering from a solid with C ₆₀ ⁺ bombardment.