Investigations of the structural, morphological and electrical properties of multilayer ZnO/TiO2 thin films, deposited by sol–gel technique

Investigations of the structural, morphological and electrical properties of multilayer ZnO/TiO 2 thin films deposited by sol–gel technique on glass substrate. Sol–gel is a technique in which compound is dissolved in a liquid in order to bring it back as a solid in a controlled manner. TiO 2 solution was obtained by dissolving 0.4 g of TiO 2 nano powder in 5 ml ethanol and 5 ml diethylene glycol. ZnO solution was obtained by dissolving 0.88 g zinc acetate in 20 ml of 2-methoxyethanol. X-ray diffraction (XRD) (PW 3050/60 PANalytical X’Pert PRO diffractometer) results showed that the crystallinity is improved when the number of ZnO/TiO 2 layers increased. Also it shows the three phases (rutile, anatase and brookite) of TiO 2 . Surface morphology measured by scanning electron microscopy (SEM) (Quanta 250 fei) revealed that Crakes are present on the surface of ZnO/TiO 2 thin films which are decreased when the number of ZnO/TiO 2 layers increased. Four point probe (KIETHLEY instrument) technique used to investigate the electrical properties of ZnO/TiO 2 showed the average resistivity decreased by increasing the number of ZnO/TiO 2 layers. These results indicated that the multilayer thin films improved the quality of film crystallinity and electrical properties as compared to single layer.