Abstract: Crystalline silicon carbon nitrides were synthesized on quartz glass substrates by microwave plasma chemical vapor deposition, using precursors produced from a pulsed nitrogen ion beam sputtering dicyandiamide target. The effects of deposition temperature on the morphology, composition and structure of the samples were investigated by scanning electron microscopy, energy dispersive X-ray, X-ray diffraction and X-ray photoelectron spectroscopy. It is found that the surface morphologies of the deposits change from well crystallized hexagonal crystals at 800 ℃ to semi-developed multi-sheet crystals at 700 ℃ and to an amorphous solid with small grains at 550 ℃. The intensity of the diffraction peaks decreases and the values of the cell parameters a and c increase with the deposition temperature. The as-prepared crystalline films are silicon carbonitride with the crystalline structure of Si3N4 modified by replacing some of the Si atoms with C atoms. The N atoms are mainly bonded to Si, and C atoms are in the form of sp³C—N, sp²C=N and sp²C=C bonds. Decreasing deposition temperature favors an increase of C atom content and sp³C—N bond fraction.