We investigated the optical absorption properties of Nb x Ti 1−x O 2 thin films, a solid solution combining the reduced titanium and niobium oxide phases TiO 2 and NbO 2. The optical absorption properties of Nb x Ti 1−x O 2 thin films prepared by pulsed laser deposition at 600 °C were shown to be large in magnitude at an almost constant value of ≈17 µm −1 . Because this large absorption coefficient is nearly independent of incident photon energy in the visible range (400–700 nm), the Nb x Ti 1−x O 2 thin films appear optically black. Flat and homogenous, optically black coatings like these are desirable for color isolation in flat panel displays. The origin of flat wavelength dispersion in Nb x Ti 1−x O 2 is the coexistence of semiconducting absorption and metallic light absorption mechanisms. Localized Nb-Nb dimers in the metallic Nb x Ti 1−x O 2 phase open an optical band gap which gives rise to semiconducting behavior. We show here that reduction results in strong visible light sensitization in normally transparent Nb-Ti oxides.
ASJC Scopus subject areas
- 化学 (全般)