Effect of hydrogen on the growth of thin hydrogenated amorphous carbon films from thermal energy radicals

Molecular dynamics simulations have been performed to investigate the growth of thin hydrogenated amorphous carbon (a-C:H) films from radical species with thermal energy. It is found that the incorporation of H into the film increases the mass density. The maximum mass density is reached for a H flux of about 10%. The atom density of the films reaches a maximum at a H flux of about 30%. It is shown that these effects are a result of the change in microstructure of the films, including a H-induced sp to sp2 to sp3 shift. These results are important for thin a-C:H film deposition techniques where chemisorption of radical species is the main growth mechanism.