Films of nitrogen-doped TiO2 have been successfully deposited on a Si substrate by radio frequency reactive sputtering in a mixture of argon, oxygen and nitrogen. The nitrogen gas ratio varies in the range 0.2–0.4 during the deposition, resulting in TiOxNy films with 3% ≤ y ≤ 6.55% as determined by x-ray photoelectron spectroscopy (XPS). Chemical bond state analysis by XPS indicates that nitrogen is effectively incorporated and produces an oxynitride centre as oxygen is replaced by nitrogen. Characterization by atomic force microscopy demonstrates that the incorporation of nitrogen has a significant effect on the morphology of the targeted TiO2 thin films. Spectroscopic ellipsometry with a photon energy of 0.75–6.5 eV at room temperature has been carried out to derive the refractive index n and the extinction coefficient k on the basis of a new amorphous dispersive model. The optical constants such as absorption coefficient, complex dielectric functions and the optical band gap have been determined. The trend of a decrease in the optical band gap with an increase in nitrogen concentration is consistent with the observation determined by UV–visible spectroscopy. The reduced band gap is associated with the N 2p orbital in the TiOxNy films.

Strong photoluminescence bands range from 300 to 600 nm at room temperature have been observed in anodic alumina membranes (AAM). It was found that the photoluminescence (PL) intensity and peak position of AAM depend strongly on the excitation wavelength, and the PL intensity of AAM prepared in C2H2O4 is much higher than for AAM prepared in H2SO4. There are two peaks in the PL bands; one is at constant wavelength of 460 nm, and the other increases almost linearly from 420 to 465 nm with excitation wavelength for AAM prepared in C2H2O4 and from 360 to 465 nm for AAM prepared in H2SO4. Annealing treatment of the as-prepared AAM results in an apparent reduction of the intensity of the blue emission at shorter excitation wavelength, while at longer excitation wavelength (longer than 320 nm) the PL intensity firstly increases, and at 500 °C reaches a maximum value, then decreases. It is considered that there are two PL centres; one originates from the oxygen-related defects in the barrier layer, and the other is correlated with the aluminum incorporated into the anion-contaminated alumina layer in the AAM.

Nanocrystalline δ-Bi2O3 thin films have been deposited onto Si (100) and quartz substrates by reactive sputtering. The structural characteristics and thermal stability of the thin films have been investigated by x-ray diffraction and Raman spectra. It was found that the δ-Bi2O3 thin films could exist stably below 200 °C and undergo a phase transition sequence δ → β → α with increasing annealing temperature beyond 200 °C. These phase transitions were further confirmed by optical constant and optical band gap studies.