Characterisation of nitrogen modified diamond-like carbon films deposited by radio-frequency plasma enhanced chemical vapour deposition

Abstract Diamond-like carbon (amorphous hydrogenated carbon: a-C:H) coatings with different contents of nitrogen were deposited by radio-frequency (r.f.) plasma enhanced chemical vapour deposition on silicon, steel and glass substrates. The plasma was sustained with a r.f. power generator at 13.56 MHz. In addition to argon and acetylene, nitrogen gas was used for modifying the structure of the carbon–hydrogen network. The content of nitrogen was tailored up to 15 at.%. While the Ar/N 2 /C 2 H 2 or respectively the flow ratio were changed for realising different nitrogen contents, the final pressure of 1×10 −2 Pa was kept fixed. In order to deposit N-modified carbon–hydrogen films, the power was adapted. For comparison, not modified a-C:H films were deposited by using a gas mixture of Ar/C 2 H 2 . Information about the films microstructure is given by Raman and nuclear magnetic resonance (NMR) spectroscopy as well as high resolution transmission electron microscopy (HRTEM). The structure of the films is correlated to the Martens hardness and sliding wear resistance (ball-on-disk tests).