A Raman study of diamond film growth on cemented tungsten carbide

Phase purity and crystallinity of diamond films grown by Hot Filament CVD on WC-6wt.% Co have been studied by Raman spectroscopy as a function of deposition conditions and substrate pretreatments. High-quality diamond films were grown using 0.5% CH4/H-2 in a narrow range of substrate temperatures (750-760 degrees C). The linewidth of the diamond Raman peak increased with the deposition temperature. This effect has been ascribed to a higher density of defects in diamond crystallites. Chemical etching of the substrate before deposition was not as effective as a careful selection of deposition parameters to reduce the co-deposition of non-diamond carbon phases. This finding has been attributed to the fast diffusion of the binder from the bulk to the substrate surface, even for the etched substrates.