Properties of TiO₂-based transparent conducting oxides

The development and properties of titanium dioxide (TiO₂)- based transparent conducting oxides (TCO), which exhibit properties comparable to those of In_2-xSn_xO₃ (ITO), are reviewed in this article. An epitaxial thin film of anatase Ti_0.94Nb _0.06O₂ exhibited a resistivity (r) of 2.3×10- 4ωcm and internal transmittance of ̃95% in the visible light region. Furthermore, we prepared polycrystalline films with r of 6.4×10-4ωcm at room temperature on glass substrates by using sputtering. We focus on characteristics unique to TiO₂- based TCO, such as a high refractive index, high transmittance in infrared, and high stability in reducing atmospheres. Possible applications of TiO₂-based TCOs, as well as the mechanism of the transparent conducting properties found in this d-electronbased TCO, are discussed in this review. (Figure Presented) Photograph showing TiO2-based TCO on a transparent plastic film. Note that the film appears greenish due to interference in the film originating from its high refractive index. This high refractive index is one of the unique characteristics of TiO₂- based TCO.