Carbon nitride films prepared by magnetron sputtering were studied by multiwavelength Raman spectroscopy. The low/intermediate wavenumber features observed near 400 and $700{\mathrm{cm}}^{-1}$ are addressed, and the relaxation of the Raman selection rule due to curvature of the graphene planes in the nanoparticles (similar to carbon nanoonions) embedded in $\mathrm{C}{\mathrm{N}}_x$ thin films is invoked to explain the possible origin of the near $700{\mathrm{cm}}^{-1}$ band. The shift in the $G$ peak center and $I_D∕I_G$ ratio are correlated with the observed microstructural changes (published before) in order to understand the effect of nitrogenation and deposition temperature on the structure of the films.

• Received 8 March 2004

DOI:https://doi.org/10.1103/PhysRevB.70.035406