Effects of methane concentration on diamond spherical shell films prepared by DC-plasma jet CVD

Diamond spherical shell films with different methane concentrations were deposited by DC plasma jet CVD method. The morphology, impurities, internal fiber texture and surface roughness of diamond film were investigated by scanning electron microscopy, Raman spectroscopy, X-ray diffraction and roughness profile meter respectively. The results show that, at the beginning of diamond nucleation, diamond crystallites orientation was random, and influence of CH4 concentration was negligible. At a low CH4 concentration (1%) and the substrate temperature of 850 °C, high quality diamond film was prepared. The film structure was polycrystalline and (111) face was dominant. When CH4 concentration was increased, diamond film has more local clusters, amorphous graphite. Thus, higher CH4 concentration has negative influence on preparing high quality diamond film.