Effects of RF Power on the Optical Properties of ZnO/TiO<sub>2</sub> Nanocomposites Prepared by RF Magnetron Sputtering and Solution-Immersion Method

Abstract

Nanocomposites of ZnO/TiO2 were fabricated by two methods. Firstly, deposition of TiO2 nanoparticles by Radio Frequency (RF) magnetron sputtering. Secondly, growths of ZnO nanostructures on the TiO2 nanoparticles by solution-immersion method with aqueous solution of Zinc nitrate hexahydrate as precursor solution and stabilizer hexamethylenetetramine (HMTA) in water as solvent. The optical properties of ZnO/TiO2 nanocomposites were examined by Ultraviolet-Visible (UV-Vis) spectroscopy, Raman spectroscopy and Photoluminescence (PL) spectroscopy. UV-vis spectra of ZnO/TiO2 nanocomposites display high absorption in the UV region and high transparency in the visible region. There is improvement in UV absorption for ZnO/TiO2 nanocomposites compared to pure TiO2 due to imperfect alignment of ZnO nanostructures. Raman analysis shows the presence of wurtzite hexagonal ZnO in all the films and presence of anatase structure of TiO2 in the film deposited at 200 W. PL spectra of the films show the emissions in the UV and visible regions. Intensity of PL emission in UV region (λ< 400 nm) is maximum for film deposited at 200 W and minimum for film deposited at 300 W resulting from the change in the surface state density. A broad peak from ~ 600-700 nm also was found for all the films.