Direct identification of the synergism between methyl radicals and atomic hydrogen during growth of amorphous hydrogenated carbon films

The simultaneous interaction of methyl radicals (CH3) and atomic hydrogen ( H) with the surface of amorphous hydrogenated carbon (a-C:H) film is invest igated. Two identical quantified beam sources for H and CH3 are used. The g rowth and/or erosion during the simultaneous interaction of the two beams w ith an amorphous hydrogenated carbon film is monitored by using in situ rea l-time ellipsometry at a substrate temperature of 320 K. Interaction with t he CH3 beam alone causes slow growth, corresponding to a sticking coefficie nt for CH3 of similar to 3x10(-5). Simultaneous interaction of the atomic h ydrogen beam and the CH3 radical beam yields a sticking coefficient for CH3 of 3x10(-3), which is two orders of magnitude larger than for CH3 alone. F rom a microscopic modeling of this synergistic growth, the reaction probabi lity for CH3 adsorbing at an adsorption site, which is created by atomic hy drogen at the surface, is derived to be 0.14. (C) 2000 American Institute o f Physics. [S0003-6951(00)01306-1].