Carbon and composite carbon-metal films deposited in an rf glow discharge operated in organic gases

Abstract

In recent years very hard (diamond-like, i-C or a-C:H) carbon films have attracted great attention due to their unusual properties such as refractive index, transparency in the infrared region, hardness, resistivity and chemical inertness. Main techniques developed for production of such films and their basic properties are reviewed. In the present work plasma depotition using an rf glow discharge operated in hydrocarbon gases has been employed because of its relative simplicity. The films were grown in a conventional rf (20 MHz) diode system, where the substrate were mounted on the excitation electrode developing negative self-bias as a consequence of its capacitive coupling to the power supply. Various kinds of carbon films involving polymer and hard carbon (a-C:H) have been prepared depending on the bias voltage and the working gas pressure in the system. An attempt has been made to study the effect of adding halocarbons to the hydrocarbon gases. The film optical properties were measured and given in connection with the film structure (IR spectroscopy) and composition (AES, ESCA) resulting from the deposition conditions. Metal incorporation into carbon matrices grown from organic gases in glow discharges under mild as well as high energetic bombardment are considered. The results of our experiments in this respect are discussed with regard to the basic film properties and potential applications of the layers.