Structure studies of C3N4 thin films prepared by microwave plasma chemicalvapour deposition

Crystalline carbon nitride films have been synthesized on Si(100) substrate s by a microwave plasma chemical vapour deposition technique, using a gas m ixture containing nitrogen and methane at various ratios as precursors. Sca nning electron microscopy shows that the films consisted of hexagonal cryst alline rods, which are about 1-2 mum long and about 0.4 mum wide. X-ray dif fraction and transition electron microscopy indicate that the films are mai nly composed of alpha- and beta -C3N4, and these results match more closely with the alpha -C3N4 than with the beta -C3N4 phase. Fourier transform inf rared absorption spectra of carbon nitride films support the existence of a lpha- and beta -C3N4.