A NEXAFS CHARACTERIZATION OF ION-BEAM-ASSISTED CARBON-SPUTTERED THIN-FILMS

Thin carbon films were deposited by sputtering with various species by means of the technique of dynamic ion mixing (DIM). Transmission electron microscopy experiments reveal that the films are amorphous and contain contaminants, mainly oxygen. Density values are determined by glancing X-ray reflectometry. Friction and wear resistance measurements have been accomplished. Near-edge X-ray absorption fine structure (NEXAFS) experiments are performed at both CK and OK edges. The CK edge NEXAFS data for a film obtained with DIM and an argon-methane mixture filling the sputtering source show a strong peak that is attributed to C-H and O=C-OH bonds, while the number of sp(2)-hybridized carbon sites is quite small. More damped features are observed for a film deposited without DIM when an argon-hydrogen mixture is used. However, the number of sp(2)-hybridized carbon sites is then greater. When DIM is used, we observe in the NEXAFS spectrum that the high energy ion irradiation induces hydrogen release. A correlation of the NEXAFS with the wear behaviour is suggested.