Structure and characteristics of C3N4 thin films prepared by rf plasma-enhanced chemical vapor deposition

C3N4 films were prepared on Si(111) by rf plasma-enhanced chemical vapor deposition using Si3N4/TiN and Si3N4/ZrN as transition layers. X-ray diffraction and transmission electron diffraction revealed that the films deposited have a polycrystalline structure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy confirmed the presence of sp(3) and sp(2) hybridized C atoms tetrahedrally and hexagonally bonded with N atoms, respectively. The nitrogen concentration was calculated from the XPS spectra. Graphite free C3N4 films were obtained under optimal conditions. The Vickers hardness of the C3N4 films falls in the range of 2950-5100 kgf/mm(2). The C3N4 films exhibit high resistance against acid and electrochemical etching. Thermal gravimetric and differential thermal analysis showed that the films are thermally stable at temperatures ranging from room temperature to 1200 degrees C.