Effect of molarity of TiO₂ seeded-template to the growth of ZnO nanostructures

ZnO nanostructures were deposited by solution-immersion method on TiO₂ layers by sol-gel spin-coating technique. Seven layers of TiO₂ were coated on glass substrates at different molarities, followed by annealing treatment and solution-immersion process in aqueous solution containing 1:1 ratio of 0.05 M of zinc nitrate hexahydrate (Zn(NO₃)₂.6H₂O) and hexamethylenetetramine (HMTA) (C₆H₁₂N₄). FESEM images confirmed that ZnO nanostructures grown on TiO₂ seeded-template are in needle-like shape with smaller tip can be observed. Photoluminescence (PL) spectroscopy showed that as the molarity of TiO₂ seeded- template increase, the intensity of PL emission at UV region decrease. UV emission peak for 0.10 M and 0.25 M are higher compared to UV emission peak film of 0.50 M and 1.00 M, which are too low. Meanwhile, the UV absorption properties of the nanostructured thin film for 0.25 M of TiO₂ seeded-template was higher compared to other thin films. (paper)