Synthesis of diamond/beta-SiC composite films by microwave plasma assisted chemical vapor deposition

A new kind of micro-crystalline composite films consisting of diamond and cubic silicon carbide (B-SiC) has been synthesized in a microwave plasma assisted chemical vapor depossition process (MWCVD), using a gas mixture of hydrogen, methane and tetramethylsilane. Single crystalline (111) silicon and polycrystalline tungsten carbide wafers, which were treated with diamond paste before the deposition, were used as substrates. Scanning electron microscopy, electron probe microanalysis, infrared absorption, Raman scattering and x-ray diffraction analysis were performed to characterize the film quality and the crystallographic structure. The results show that the film structure and the volume ratio of diamond and ß-SiC components depend mainly on theht reactive gas concentrations and on the diamond nucleation densiry. By adjusting the reactive gas concentration, the volume ratio of the components can be varied over the film thickness. In addition, the growth texture of the diamond phases ca n be influenced by the ß-SiC phase orientation.