SYNTHESIS AND CHARACTERIZATION OF PURE CRYSTALLINE C-N FILM

We report successful experimental synthesis of pure crystalline C-N fi lm on silicon and nickel substrates by bias-assisted hot filament chem ical vapor deposition (bias-HFCVD). The obtained films have been firml y characterized by energy dispersive X-ray (EDX) and Auger electron mi croscopy for the chemical composition, X-ray diffraction (XRD) and sel ective-area electron diffraction (SAED) for the lattice structure, and scanning electron microscopy (SEM) and transmission electron microsco py (TEM) for the crystal morphology and symmetry. Our experimental lat tice constants of alpha-C3N4 (a = 6.38 Angstrom, c = 4.648 Angstrom) a nd beta-C3N4 (a = 6.24 Angstrom, c = 2.36 Angstrom) with a relative N/ C composition of 1.30-1.40 on nickel are in good agreement with the ab initio calculations by less than 1.3% and 2.5%, respectively. A new t etragonal C-N phase with a = 5.65 Angstrom and c = 2.75 Angstrom was i dentified for the first time in the laboratory. Furthermore, a specifi c C3N4 phase growth was studied by adding a fraction of hydrogen. A '' lattice match selection'' for the growth of C3N4 crystals on silicon i s proposed.