X-ray photoelectron spectroscopic observation on the formation of carbon nitride thin films produced by low-energy nitrogen ion implantation

X-ray photoelectron spectroscopy (XPS) spectra of N 1s and C 1s were measured for carbon nitride thin films prepared by low-energy nitrogen ion implantation in graphite. To assign the XPS spectra, we also measured XPS spectra for some standard materials which have sp2 or sp3 C-N bond configurations. In N 1s XPS spectra for the ion-implanted graphite, we found three clear peaks at the binding energies of EB = 398.3, 400.3, and 402.6 eV. However, in spite of the difference in bonding systems, all the carbon nitride compounds showed similar N 1s binding energies corresponding to the second peak (EB = 400.3 eV). Furthermore, we found a broad structure which resulted from the formation of C-N bonds at a binding energy 2 eV higher than that of the graphite peak, by removing the damage effect from the C 1s XPS spectra for the ion-implanted graphite. Based on these results, we propose an assignment of XPS spectra for the ion-implanted graphite.