The investigation of carbon nitride films prepared at various arc currents by vacuum cathode arc method

The carbon nitride films have been prepared in the arc currents range of 20-60 A at the Ar/N₂ atmosphere of 50/400 sccm by the vacuum cathode arc deposition method. The properties of the films were characterized by x-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and nanoindentation. The N concentration showed a maximum of 35 at% at 20 A and decreased gradually with the arc currents. The films below 40 A consisted of linear polymeric-like component and sp² graphitic cluster. With the increasing of the arc current from 20 to 40 A, the I_D/I_G rose and the photoluminescence (PL) fell gradually, which resulted from the development of the sp² graphitic phase and the decrease of the polymeric-like phase. As a result, the CC bonds increased and sp³CN and sp²CN decreased. Above 40 A, with the increasing of arc currents, I_D/I_G fell and the PL increased gradually, which reflected the decreasing of sp² graphitic phase and the modification of C and N atoms in sp² cluster. The CC bonds and sp³CN fell and the sp²CN rose. The nanohardness of films showed increasing tendency with the arc currents. The variation of the relative ratio and the average energy of N-containing species and C-containing species at the atmosphere would be responsible for the change in the properties of films.