Effect of nitrogen content on the microstructure and mechanical properties of CNx thin films

There is an interest in producing new materials with extreme combinations of mechanical properties such as high-hardness and low-friction coefficients. One example of such materials is crystalline C3N4. which has been predicted to have a bulk modulus higher than that of diamond. In this work we present the X-ray photoelectron spectroscopy analysis of the CNx thin films synthesized by RF magnetron sputtering technique at different bias voltages. From these analyses we have determined an N/C ratio between 0.23 and 1.3 in the film, depending mainly on the bias voltage used. These analyses indicate that the nitrogen atoms are chemically bonded with carbon in various types of bonds such as C-N, C=N, CdropN. The topography and morphology of CN, films at different sputtering conditions were determined by atomic force microscopy. These analyses show the high dependence of the morphology of the films with the deposition parameters. The hardness of films measured by means of the nano-indentation method was between 7 and 25 GPa. (C) 2003 Elsevier B.V. All rights reserved.