A novel structure of tungsten carbide nanowalls grown on nanocrystalline diamond film

Abstract

We report the fabrication of a novel structure of tungsten carbide nanowall on the nanocrystalline diamond substrate by a simple technique. The substrate was exposed to the hydrogen plasma generated in a direct-current plasma chemical vapor deposition system using a pre-carburized tungsten cathode. The physiochemical reaction between the carburized tungsten cathode and hydrogen plasma enabled the growth of tungsten carbide nanowalls at a particular temperature of 600 °C, which has never been enabled to date. Scanning electron microscopy, transmission electron microscopy, electron energy loss spectroscopy, and X-ray photo-emission spectroscopy were used to investigate the structure and composition of the samples. It was found that the nanostructure was strongly affected by the substrate/cathode temperatures: the nano-grained, continuous polycrystalline film formed at a higher temperature (800 °C) while the discrete tungsten carbide nanowalls formed at a lower temperature (600 °C). Such a drastic change in the nanostructure was interpreted in terms of the change in the super-saturation of growth species according to the experimental parameters.