Deposition of crystalline C3N4 films via microwave plasma chemical vapour deposition

Crystalline carbon nitride films have been synthesized on polycrystalline Ni substrates by a microwave plasma chemical vapour deposition technique, using a mixture of N2, CH4 and H2 as precursor. Scanning electron microscopy shows that the film consisted of perfect crystals of short and long hexagonal bars, tetragonal bars and irregular particles. From the X-ray photoelectron spectroscopy (XPS) data, a maximum N/C ratio of 1.0 was achieved in the films. The XPS spectra of the film typically showed three peaks in the C 1s core spectrum (centered at 284.78, 285.94, and 287.64 eV) and two peaks in the N 1s core level spectrum (centered at 398.35 and 400.01 eV). This indicates that there are two types of C–N bonds; N is bonded to sp2- or sp3-coordinated C atoms in the as-deposited film. The X-ray diffraction pattern indicates that the film is composed of α-, β-, pseudocubic, graphitic C3N4 and an unidentified phase. A series of intense sharp Raman peaks were observed in the range of 100–1500 cm− 1. These peaks match well with the calculated Raman frequencies of α- and β-C3N4, revealing the formation of α- and β-C3N4 phase.