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 N-2, CH4 and H-2 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 1 s 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 sp(2)-or sp(3) -coordinated C atoms in the as-deposited film. The X-ray diffraction pattern indicates that the film is composed of alpha-, beta-, 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 alpha- and beta-(CN4)-N-3, revealing the formation of alpha- and beta-C3N4 phase. (c) 2006 Elsevier B.V. All rights reserved.