Dynamic Monte Carlo simulations with the binary collision approximation have
been applied to the synthesis of hydrogenated amorphous carbon
(a-C:H) films by plasma based ion implantation (PBII).
We take as representative carbon carriers energetic CH3+ ions and CH3 radicals. The direct chemical
incorporation of the radicals, like CH3 reacting with a diamond
surface, is too low for the deposition of DLC films, so that the other
reaction mechanisms should be responsible. We assumed (a) complete
dissociation of CH3+ ions into one C atom and three H atoms with identical
velocities upon bombarding the surface, (b) a unity and only one mono-layer
sticking of CH3 radicals on the surface, (c) incorporation
(stitching) of H and C atoms under the surface induced by binary collisions
with energetic CH3+ ions, (d) release of H atoms by the dissociation of
CH3 radicals on the surface, and (e) release of a part of
displaced H atom after the subsequent collision cascade. We also assumed
only the stitched carbon atoms form sp3 states and all other
carbon atoms form sp2 states. The effect of the target voltage on
the ion dose was also included. The effects of ion/neutral arrival ratio and
ion energy on the growth rate, the mixing layer thickness, the hydrogen
content, and the sp3/sp2 ratio in the deposited film
are presented.