Investigation of nucleation and adhesion of diamond films on mirror-smooth glass substrates

Diamond films were deposited on mirror-smooth glass substrates. Two types of pretreatments of glass substrate were performed: scratching with diamond powder and preparation of TiO2 interlayer. The diamond films were examined with micro-Raman spectroscopy and scanning electron microscopy (SEM). The TiO2 interlayer treated by hydrogen plasma was analyzed by X-ray photoelectron spectroscopy (XPS). It is found that the TiO2 interlayer can result in a higher nucleation density and a better adhesion than scratching pretreatment. The enhancement of the nucleation density using TiO2 interlayer is attributed to the effects of some low valence Ti that was produced by the hydrogen plasma treatment. The observed improvement in film adhesion could be due to the formation of Ti–C chemical bonding between the TiO2 interlayer and the deposited diamond film as well as good adhesion of the TiO2 interlayer to the glass substrate.