Effects of hydrogen incorporation in the formation of hydrogenated diamond-like carbon films

The formation process of sp hybridized carbon networks (i.e., diamond-like structures) in hydrogenated diamond-like carbon (DLC) films has been studied with the use of molecular dynamics (MD) simulations. A recent study [Y. Murakami, S. Horiguchi, and S. Hamaguchi, Phys. Rev. E. (2010) in press] has shown that a sufficient supply of hydrogen in the form of hydrocarbon species CH3 as deposition precursors significantly enhances the formation of sp hybridized bond structures in the deposited film. In this study, we have examined the role of hydrogen in such deposition processes by simulating the cases where carbon and hydrogen atoms are supplied to the surface separately. It has been found that, in such a case, the rate of sp bond formation is significantly lower than that in the corresponding case of CH3 injections. The result suggests that energetic hydrogen atoms present in the vicinity of the incident carbon atoms promote the formation of σ bonds (and therefore sp bonds) among carbon atoms by increasing the rates of π bond termination and hydrogen abstraction reactions.