Effect of an optical emission spectrometer feedback-controlled method on the characterizations of nc-TiC/a-C:H coated by high power impulse magnetron sputtering

Abstract

An optical emission spectrometer (OES) feedback-controlled high power impulse magnetron sputter deposition system was used to deposit nc-TiC/a-C:H thin films in a reactive mode. The plasma emission intensity of Ti2+ ions at the emission wavelength of 365nm was monitored and the amount of reactive C2H2 gas was precisely controlled to maintain stable emission intensity during the deposition process. By controlling the C2H2 input flow rate and different Ti2+ ion optical emission intensities, various nc-TiC/a-C:H thin films were obtained at a fixed duty cycle of 2% and repetition frequency of 500Hz at 75°C. The characteristics and mechanical properties of the obtained films were also investigated. As the OES set point was 40%, the phase changing from TiC to nc-TiC/a-C:H films was clearly identified. The highest hardness of 26GPa was obtained at the OES set point of 40%, where the film was composed of TiC. In addition, the lowest friction coefficient of 0.08 was obtained at the OES set point of 7%, which represented the nanocomposite structure of nc-TiC/a-C:H films.