Growth of crystalline tungsten carbides using 1,1,3,3-tetramethyl-1,3- disilacyclobutane on a heated tungsten filament

A method of forming crystalline tungsten carbides was reported by exposing the heated tungsten filament to 1,1,3,3-tetramethyl-1,3-disilacyclobutane (TMDSCB) in a hot-wire chemical vapor deposition process. Methyl radicals produced from the decomposition of TMDSCB on the filament serve as the carbon source. The formation of tungsten carbides was investigated by X-ray diffraction, cross-sectional scanning electron microscopy, and in-situ filament resistance measurements. A pure W₂C phase was formed at a high temperature of 2400 °C after 1-2 h exposure time with a growth rate of 4.4 μm min^-1. The growth of the W₂C layer is found to be a diffusion-controlled process. Our study at longer deposition time of 3-4 h shows that once the metal filament is fully carburized to form W₂C, the carbon-rich WC phase starts to form on the outside layer upon further exposure to TMDSCB. A WC layer with no contamination from the W₂C phase was found to be formed at 2400 °C and 4 h deposition time.