(Ta2O5)1−x(TiO2)x deposited by photo-induced CVD using 222 nm excimer lamps

We report the deposition of thin (Ta2O5)1−x(TiO2)x films on quartz and crystalline p-type Si (1 0 0) by photo-induced CVD using 222 nm excimer lamps at temperatures from 50 to 350 °C. The alkoxide precursors titanium isopropoxide and tantalum tetraethoxy dimethylamenoethoxide were mixed in various ratios, vaporised, and then driven into the reaction chamber by an Ar carrier gas, where they were exposed to the UV radiation. Films greater than 500 nm in thickness were grown at a pressure of several millibars and at a deposition rate of approximately 60 nm/min at 350 °C. The chemical bonding of the films has been analysed by Fourier transform infrared spectroscopy, and indicated that both Ta2O5 and TiO2 stretching absorption peaks were present. The optical properties of the layers were analysed by UV–Vis spectroscopy between wavelengths of 195–1100 nm. Band gap energies ranging between 3.2 and 4.2 eV were obtained for films of various compositions.