Comparative study of the structure of a-CNx and a-CNx:H films using NEXAFS, XPS and FT-IR analysis

The combination of both characterizations FT-IR and NEXAFS may leave the controversy about the interpretation of the XPS spectra, and allows a fine analysis of the evolution of the local structure as a function of nitrogen incorporation, according to the hydrogen concentration into the films. Fundamental differences can be revealed between hydrogenated and hydrogen-free carbon nitride: in the former, hydrogen promotes double bonds CNH, whereas in the latter nitrogen atoms prefer to substitute to carbon or interconnect aromatic rings through single bonds (>CN). A strong conjugation of imines (NCNH) for PECVD film and nitrile (NCN) groups for hydrogen-free films is evidenced.