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Carbon nitride films were grown on Si(100) substrates using d.c. magnetron sputtering with r.f. bias. Reactive deposition was achieved using a graphite target in an argon/nitrogen plasma. These films were characterized by transmission electron microscopy (TEM), XPS and Fourier transform infrared spectroscopy (FTIR) spectroscopy. Relatively large carbon nitride crystal grains in polycrystalline structures were observed with TEM. According to calculations from electron diffraction patterns, these crystalline structures were hexagonal β-C3N4. From XPS data, N/C ratios in the films were calculated to be in the range of 0.18–0.5. The XPS spectra of the films typically showed three peaks in the C 1s core-level spectrum (centred at 284.6, 285.9 and 287.2 eV) and two peaks in the N 1s core-level spectrum (centered at 398.7 and 400.2 eV). This indicates that there are two types of CN bonds; N is bonded to sp2- or sp3-coordinated C atoms in the as-deposited films. The FTIR spectra showed three absorption bands in the range 1000–3000 cm−1. The absorption band at ∼2367 cm−1 can be attributed to the CN nitrile bond. The absorption bands at ∼1559 cm−1 and 1201 cm−1 demonstrate the existence of CN (sp2) and CN (sp3) bonds. Moreover, the relative absorption intensity of CN bonds seems to increase with increasing nitrogen content. Both XPS and FTIR measurements showed the presence of fourfold-coordinated β-C3N4 crystals in the films, which is in good agreement with TEM and electron diffraction results. Copyright © 1999 John Wiley & Sons, Ltd.
Wei et al. (Sun,) studied this question.