Preparation and characterization of ultrananocrystalline diamond films in H2/Ar/CH4 gas mixtures system with novel filament structure

Diamond films were prepared by hot filament chemical vapor deposition (HFCVD) in a gas mixtures system of methane, argon and hydrogen. The composition and morphology in different deposition pressures and filament structures were investigated, as well as the friction and wear-resistant properties. The sp(3)-bonded content was measured and nano-mechanics properties were also tested. Results of atomic force microscopy and X-ray photoelectron spectroscopy show that the diamond films whose surface roughness is less than 10 nm and sp(3)-bonded content is greater than 70% can be prepared by bistratal filament structure with optimized proportion of Ar. It is also shown that the friction coefficient of diamond films is 0.13 and its wear-resistant property is excellent. Nano-mechanics of films shows that its elastic modulus is up to 650 MPa and hardness can reach higher than 60 GPa. The diamond films with excellent performance have a broad application prospect in microelectromechanical systems (MEMS).