The crystalline carbon nitride thin films have been prepared on Si (100) su
bstrates using microwave plasma chemical vapor deposition technique. The ex
perimental X-ray diffraction pattern of the films prepared contain all the
strong peaks of alpha-C3N4 and beta-C3N4, but most of the peaks are overlap
ped. The films are composed of alpha-C3N4 and beta-C3N4. The N/C atomic rat
io is close to the stoichiometric value 1.33. X-ray photoelectron spectrosc
opic analysis indicated that the binding energies of C 1s and N 1s are 286.
43 eV and 399.08 eV respectively. The shifts are attributed to the polariza
tion of C-N bond. Both observed Raman and Fourier transform infrared spectr
a were compared with the theoretical calculations. The results support the
existence of C-N covalent bond in alpha- and beta-C3N4 mixture.