Polycrystalline carbon nitride films were synthesized using the rf diode sputtering technique. The carbon nitride films were evaluated with IR spectroscopy, X-ray diffraction and Auger electron spectroscopy. The more important findings are that polycrystalline C 3 N 4 films could be deposited on single-crystal Si(111) wafers at ambient temperatures during deposition and the nitrogen-carbon concentration ratios χ = [N] attained the stoichiometric value 1.33 required for the C 3 N 4 structure in the films.