Amorphous hydrogenated carbon-nitrogen films were deposited by plasma enhanced chemical vapor deposition (PECVD) using acetylene-nitrogen mixtures. The atomic composition and density of the films were determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERDA). Raman and Infrared spectroscopies monitored their structure. The addition of nitrogen gas to the deposition atmosphere resulted in a decrease in the film deposition rate. The increase of the nitrogen content is accompanied by the reduction of the carbon content. The IR absorption spectra show an increase intensity of the C=N Raman band and the N-H and CsN stretching bands. On the other hand, the IR results show a decrease in the intensity of the C-H stretching band. Raman results suggest an increase with the nitrogen content of the fraction of carbon atoms in a sp2 state of hybridization with the nitrogen content. The internal compressive stress has been measured by the determination of the bending of the substrate; a reduction of up to 50 % has been observed depending on the nitrogen content.

Thin films composed of carbon and nitrogen were synthesized by hot-filament chemical vapor deposition method. Deposition method was developed by replacing a filament material from metals to graphite to ascertain two effects; (1) prevention of contamination from the filament material and (2) feasibility of synthesis of hydrogen free films without using hydrocarbon gas such as methane. Films were synthesized from pure nitrogen gas and hot graphite filament. Synthesized films were characterized by Auger electron spectroscopy, Raman spectroscopy, X ray diffraction, atomic force microscopy and nano indentations. It is found that the synthesized films are amorphous with the smooth and uniform surface and show the elastic behavior.

CNx films were deposited using pulsed laser deposition (PLD) and ion beam deposition (IBD). The PLD films deposited at substrate temperature Ts = 25°C and high N2 partial pressure have the highest N content (fN) and polymerlike structure, accompanied by large band gap (Eg) and low electrical conductivity (σroom). The rise in Ts lowers fN and induces graphitization of the film structure, so Eg reduces and σroom increases. IBD (with and without N2+ assist) films are graphitic. Higher Ts further enhances the graphitization of the film structure, such that the conduction and valence bands overlap, and σroom approaches to that of graphite. No evidence was found to show successful formation of the hypothetical β-C3N4 phase in the films.

High quality crystalline Si-C-N films on silicon substrate have been synthesized by bias-assisted hot filament chemical vapor deposition (CVD) using a gas mixture of nitrogen and methane. Scanning electron microscopy images show that the Si-C-N clusters are composed of many columnar crystals with hexagonal facets. X-ray diffraction and transmission electron microscopy analyses confirm the formation of Si-C-N crystals with lattice parameters a=7.06Å and c=2.72Å. First principles calculations are performed for β-Si3–nCnN4 (n=0,1,2,3). The calculated results support the experimental structural characterization and provide further insight into the property of the system. With increasing amount of C substitution, the bulk modulus progressively increases to 4.44 Mbar, comparable to that of diamond (4.43 Mbar), and both a and c are reduced but the ratio c/a shows little variation.