Effects of silicon surface amorphization on single carbon atom deposition/implantation

The deposition of carbon on an amorphous silicon surface is modelled by using molecular dynamics simulations combined with a third generation force field that includes bond breaking and formation. The results are compared to carbon deposition on a crystalline (100) surface in order to investigate the effects of the substrate amorphization. This amorphization may lead to a deeper or a shallower implantation of the carbon atom, depending on its initial trajectory. If the trajectory leads to a channelling effect in the crystalline surface, the implantation is shallower in the amorphous substrate and if not, the implantation is deeper in the amorphous substrate than in the crystalline one. It is also observed that under-coordinated silicon atoms at the amorphous surface tend to increase the sticking coefficient. This holds particularly true for conditions where a relatively high backscattering yield of the carbon atom on the crystalline surface is observed, as the under-coordinated silicon atoms play the role of traps, catching more carbon atoms at the surface than the silicon surface atoms in the crystalline model. (C) 2012 Elsevier B.V. All rights reserved.