Diamond-like carbon films formed by a filtered fast atom beam source

A method to filter the diamond-like carbon (DLC) film forming neutral and ionic radicals coining out from a saddle-field fast atom beam (FAB) source is suggested. By flowing different hydrocarbon gases (CH4 and C2H2) through this modified FAB source, DLC films have been grown simultaneously, by beams of neutral and ionic radicals at different locations of the reactor. Current density measurements of these two types of beams confirm the separation of neutral and ionic radicals. Energy distribution analysis of ions shows that the mean energy of the radicals lies within the limit of 50% of the applied voltage to the FAB source. The properties of the deposited DLC films grown by CH4 and C2H2 gases are compared, it is found that DLC films grown by C2H2 gas have higher hardness values than CH4-deposited films. In both the cases, films deposited by neutral radicals have higher hardness values than those deposited by ionic radicals. The values of Urbach energy (E-o) evaluated by photothermal deflection spectroscopy (PDS) technique are found to be less in the case of C2H2-deposited films than the CH4-deposited films, but neutral radical-deposited films have higher values of E-o than ionic ones, in both cases. (C) 1997 Elsevier Science S.A.