Chemical bonding in carbon nitride films studied by X-ray spectroscopies

Carbon nitride films are deposited using dc magnetron sputtering in a N₂ discharge. The nature of chemical bonding of the films is investigated using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and X-ray emission spectroscopy. X-Ray photoelectron spectroscopy spectra show that N1s binding states depend on substrate temperature, in which two pronounced peaks can be observed. The near edge X-ray absorption fine structure at C1s and N1s exhibits a similar absorption profile in the π* resonance region, but the σ* resonance is sharper in the N1s spectra. Resonant N K-emission spectra show a strong dependence on excitation photo energies. Compared XPS N1s spectra with recent theoretical calculations by Johansson and Stafstrom, two main nitrogen sites are assigned in which N bound to sp³ hybridized C and sp² hybridized C, respectively. The correlation of X-ray photoelectron, X-ray absorption, and X-ray emission spectra for N in carbon nitride films is also discussed.