Influence of deposition pressure on the structure and properties of fluorinated diamond-like carbon films prepared by RF reactive magnetron sputtering

Fluorinated diamond-like carbon films were deposited by radio frequency reactive magnetron sputtering technique with trifluoromethane (CHF3) and argon as source gases and pure graphite as a target. Structural evolutions of F-DLC films were investigated by Raman, infrared (IR) absorption, UV–visible spectra and XPS spectra. The results demonstrate that the deposition pressure controls the distribution of radicals' energy and concentration in the discharging district, which affects greatly the bonding configuration of the films. The incorporation of fluorine atoms leads to a significant distortion of the aromatic ring symmetry and modifies the sp3/sp2 hybrid ratios and bonding configurations of the films. The optical band gaps of the films are affected by the bonding configuration, and π–π* band-edge states concentration especially.