Preparation of SiCN crystals using microwave plasma CVD assisted by pulsed nitrogen ion beam sputtering

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.