Comprehensive Evaluation of the Properties of Nanocrystalline Diamond Coatings Grown Using CVD with E/H Field Glow Discharge Stabilization

The nanocrystalline diamond films (coatings) were prepared using the plasma enhanced chemical vapor deposition (PECVD) technique. In this method, direct current (DC) glow discharge in the crossed E/H fields was used to activate the gas phase. The diamond coatings were deposited from the working gas mixture CH4/H-2 with addition of nitrogen in various concentrations. It was ascertained that addition of N-2 to the working gas mixture leads to reduction in the sizes of diamond grains as well as to the substantial decrease in the resistivity of the studied films. The electrophysical data are in good agreement with the changes induced by varying the N-2 content in the Raman scattering spectra. The increase in the N-2 concentration causes significant lowering of the crystalline diamond related peak and increase in the intensity of the peaks related to the sp(2)-bonded carbon. These changes in the spectra indicate significant disordering of the structure of prepared films and its uniformity in the nanodiamond film volume. With the great possibility, it is associated with a decrease in the sizes of diamond crystalline grains and tendency of NCD film to amorphization.