Effect of SnO2 Coating on the Structural, Optical, and Electrical Properties of TiO2 Nanowires Fabricated by a Two-Step Deposition Method

The photosensing properties of SnO2-coated TiO2 NWs have been fabricated by a two-step sequential deposition method; a thermal oxidation method followed by a hydrolysis method. Pure TiO2 NWs show vertically aligned and uniformly distributed NW arrays on Ti foil. It was observed that the SnO2 coating accumulated on the TiO2 NW surfaces with increasing Sn concentration. It filled the spaces between the NWs and finally covered the entire surface of the 100 mM SnO2 concentrated sample. The presence of increased Sn concentration on the surface was qualitatively determined by EDS and XPS measurements. The PL intensity decreases as the SnO2 coating increases, indicating recombination retardation. Coating thickness also decreases the band gap since electron excitation requires less energy. Since electrons are easily excited by the conduction band of TiO2, SnO2 coatings can form an energy level within the band gap. The highest photosensitivity was 142.05% with 100-mM SnO2-coated TiO2 NW arrays. An alternative approach to photosensitive UV devices can be made with 100-mM SnO2-coated TiO2 NW arrays due to their excellent light absorption properties and efficient charge carrier generation.