Effect of Si-C bond formation in 20 keV C60 bombardment of Si

We have performed molecular dynamics (MD) simulations to investigate the effect of Si-C bond formation on fluence-dependent results in 20 keV C-60 bombardment of Si. Sputter depth profiling experiments of C-60 on Si have produced atypical results, which are thought to be caused by the strong covalent bonds that are formed between the C atoms in the projectile and Si atoms in the substrate. A recently developed scheme developed by Russo, et al.([8]) has been adapted to perform MD simulations of 150 successive impacts of 20 keV C-60 on Si, which corresponds to a total fluence of 2.64 x 10(13) impacts/cm(2). In order to isolate the effects of Si-C bond formation, the same set of trajectories is calculated with and without the attractive Si-C potential energy terms. When Si-C bonds are able to form, nearly all the C atoms from the projectile are incorporated into the substrate. When the possibility of Si-C bond formation is removed, most of the C atoms are backscattered into the vacuum. The cumulative result is that the substrate with Si-C bonds contains a factor of twenty times more C atoms, which are located below the surface. Copyright (C) 2010 John Wiley & Sons, Ltd.