Nitridation of a diamond film using 300-700 eV N₂⁺ ion beams

Diamond samples grown on Si substrates by chemical vapor deposition were nitrided at room temperature by irradiation of 300-700 eV N₂⁺ ion beams. The C 1s and N 1s XPS spectra were taken during nitridation and after annealing in ultrahigh vacuum. These spectra were tentatively divided into three components. The dominant part of the N 1s spectrum split clearly into two components of the binding energies of 398.6 and 400.8 eV after annealing. The N 1s component at approximately 398.6 eV and the C 1s component at approximately 287.8 eV are attributed to carbon nitrides such as CN_x for example, C₃N₄. The nitrogen atoms having N 1s core level of approximately 401 eV have to be positively charged compared with approximately 400 eV of neutral nitrogen. They donate electrons to the surface state and cause an upward band bending (n-type semiconductor case), which induces the peak shift of the C 1s XPS of the diamond toward a higher binding energy of approximately 285.6 eV.