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 electr on microscopy (SEM) of the carbon nitride films deposited on Si substrate a t 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 temper ature 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 d egreesC indicates no amorphous phase in the film, which is composed of beta - and alpha -C3N4 phase containing an unidentified C-N phase. Fourier trans form infrared (FTIR) and Raman spectroscopy support the existence of C-N co valent bond. (C) 2000 Elsevier Science S.A. All rights reserved.