Near-interface characterization of diamond films on silica and silicon

The diamond-film growth from nucleation sites on silica and silicon substrates were investigated by examining and comparing the near-interface structures of diamond films deposited on the two substrates from a CH4-H2 mixture by microwave plasma enhanced CVD. Free-standing diamond films were examined by SEM, TEM, electron diffraction, Raman spectroscopy, and SIMS. It was found that, on silicon, diamond formed large flat contact areas. On silica, a particulate type of intermediate layer formed first, due to chemical reactions occurring on and/or with the substrate surface. The phase content of the films deposited on both substrates was greatly affected by the methane concentration in hydrogen.