On the structure and composition of crystalline carbon nitride films synthesized by microwave plasma chemical vapor deposition

Crystalline carbon nitride thin films were prepared on Si (100) substrates by a microwave plasma chemical vapor deposition (MPCVD) method, using CH4/N-2 as precursor gases. The surface morphologies observed by scanning electron microscopy (SEM) of the carbon nitride films deposited on Si substrate at 830 degreesC were consisted of hexagonal crystalline rods. The effect of substrate temperature on the formation of carbon nitrides was investigated. X-ray photoelectron spectroscopy (XPS) analysis indicated that the maximum value of the N/C atomic ratio in the films deposited at a substrate temperature of 830 degreesC was 1.20, which is close to the stoichiometric value of C3N4. The X-ray diffraction (XRD) pattern of the film deposited at 830 degreesC indicates no amorphous phase in the film, which is composed of beta- and alpha -C3N4 phase containing an unidentified C-N phase. Fourier transform infrared (FTIR) and Raman spectroscopy support the existence of C-N covalent bond. (C) 2000 Elsevier Science S.A. All rights reserved.