Successive deposition of layered titanium oxide/indium tin oxide films on unheated substrates by twin direct current magnetron sputtering

Layered titanium oxide/indium tin oxide (TiO₂/ITO) films were successively deposited on unheated glass substrates in situ using a twin direct current magnetron sputtering system. The layered TiO₂/ITO films exhibited a strongly polycrystalline structure that comprises anatase and rutile phases, as revealed by X-ray diffraction and Raman spectra. The X-ray photoelectron spectrum of Ti2p also verified the stoichiometric state of titanium oxide near the surface. The photo-induced hydrophilic properties of the films were determined from changes in the water contact angles under ultra-violet (UV) irradiation. The results revealed that the layered TiO₂/ITO films possessed a dissipated rate of 30% when they were stored in the dark for 12 h. This result shows that the layered TiO₂/ITO films acted as “electron pools” with an inherent energy storage capability. This unique property is attributable to the rougher surface and nearly porosity-free columnar structure, which is responsible for increased UV energy absorption and loss-free hole or electron transportation.