Chemical, mechanical and electrical properties of CNx-films produced by reactive sputtering and N+-implantation in carbon films

In this work, the N effects on hard C-films properties were investigated. The C-films were prepared at 573 K by rf magnetron sputtering of a graphite target, in Ar discharge. The incorporation of N in the C-films was achieved either by N+-implantation at room temperature, with energies of 30 and 160 keV and at a fluence of 2 × 1017N+/cm2, or by reactive sputtering of graphite in a (Ar-50% N2) discharge. Hardness and elastic properties were examined using a Knoop indenter. Sliding friction measurements were made using a scratch tester. N effects on the electrical conductivity of the C-films were also studied. Atomic film composition was determined by the nuclear reaction analysis. Chemical characterization of the C- and CNx-films was obtained by X-ray photoelectron spectroscopy. The dynamical behaviour of hydrogen was studied by elastic recoil detection. The results show that the CNx-film properties were governed (i) by chemical effects and (ii) by ballistic effects, occurring during implantation, leading to a specific microstructure of the network, associated with a hydrogen redistribution in the nitrogenated films. The chemical effects are relevant mainly in the growth of the CNx-films with reactive sputtering, while the N+-implanted C-film properties are well explained by both chemical and ballistic events.