sp(2) and sp(3) bonding configurations in low nitrogen content a-CNx thin films

The results of an electron spectroscopy study carried out on a set of pulsed laser deposited CN films are reported. A progressive degree of graphitization, deduced from the continuous increase in the sp 2 bond fraction, has been found for x values up to 25%. The mass density values, deduced by a proper treating of both the x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy data, are consistent with a material made up by two phases, namely a sp2 threefold (graphite-like) and a sp3 fourfold (diamond-like) coordinated one. The behaviour of the density of the samples as a function of the N content does not show any abrupt change in going from lower to higher nitrogen concentrations as found by other authors, this certainly being due to differences in the starting sp3/sp2 ratio of the films at zero N concentration and to their different preparation parameters.