Hydrophobic nature of fluorinated diamond-like carbon films prepared under different radio-frequency power

Abstract

The fluorinated diamond-like carbon （F-DLC） films were prepared by reactive magnetron sputtering under different radio-frequency power with trifluoromethane （CHF3） and argon （Ar） as source gases and pure graphite as a target. The hydrophobic nature of F-DLC films was studied. The result of measuring contact angle between double-stilled water and film surface shows that the maximal contact angle of film surface is approximately 115°. Factors influencing the hydrophobic nature of films were discussed by film surface morphology measured by atomic force microscopy （AFM）, Raman spectra as well as FTIR spectra. The result demonstrates that the hydrophobic nature of films lies on roughness and bonding configuration of film surfaces. The more the roughness，the stroncer the hydrophobic nature is，but it doesnt show a simple decrease or increase with the content of F in films and the ratio of sp3/sp2. Radio-frequency power influences the deposition rate，which correlates with the roughness of the film，proportion of mononuclear aromatics and bonding configuration of films surface （ways of F combination）.