Sulphur doped DLC films deposited by DC magnetron sputtering



Diamond-like carbon (DLC) and sulphur doped diamond-like carbon (S-DLC) films were synthesised at different sulphur molar percentage of 0%, 2%, 5%, 8% and 10% by direct current (DC) magnetron sputtering process using novel compressed sulphur-graphite targets at relatively low power density. Films were characterised for their morphologies, structural, electrical and optical properties. Scanning electron microscope images reveal changes in the quality of the obtained films shown by the denser packing of DLC grains at different sulphur percentage. The conductivities of S-DLC films were found to be in the range of 6.0 × 10−3–0.6/Ω cm. The optical band gap energies were found to be in the range of ∼1.4–2.0 eV. Both electrical and optical measurements exhibit nonlinear responses with optimum at around 5% sulphur molar percentage (minimum for conductivity and maximum for optical band gap energy). These trends of change in both conductivity and optical band gap energy are consistent with the variation in bond characters of the films indicated by Raman spectroscopy. © 2011 Canadian Society for Chemical Engineering