The effect of postdeposition annealing on chemical bonding in amorphous carbon nitride films prepared by dc magnetron sputtering

The effects of thermal annealing on the surface morphology, composition and chemical bond structure of amorphous carbon nitride (a-C:N) films deposited by dc magnetron sputtering are reported. Atomic force microscopy (AFM) results show that thermal annealing can gradually change the surface structure of the films from a cauliflower-like texture eventually to a uniform granular texture. Fourier transform infrared absorption (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) have been used to characterise the change of chemical bonding induced by annealing. By detailed analysis of both C 1s and N 1s photoelectron spectra, we have found that annealing can break the CN bonds in the films and that the graphite-like CN bonds are relatively more stable with the increase of anneal temperature.