Synthesis, and characterization of SnO2-ZnO mixed oxide for sensingapplications

In this work , Zinc oxide thin films deposited on a glass substrate were mixed with (25, 50, and 75%) of SnO2 by use a Chemical spray pyrolyses method. An effect of mixing ratios on a structural and optical properties of ZnO films were studied. Using X-ray diffraction method, the structures of (ZnO, SnO2, ZnO: SnO2) thin films were studied. X-ray analysis of structure indicated that it is polycrystalline and that the film's crystal system is the Hexagonal and cubic . also shows that the high intensity appeared at (2θ ̊=34.3815) and that the dominant trend of growth is (0 0 2) and that a crystal size of a Pure ZnO sample is (31.601 nm) and that the size of a crystal decreases with a mixed ratio of (SnO2). From result of optical measurement by UV-ViS spectrophotometer indicated that a thin films of (ZnO, SnO2, ZnO: SnO2) exhibit direct transit energy gap transitions. An absorbance of a films increases with increasing mixing ratio. The optical constants have been determined, including the absorption coefficient (α). As the mixing ratio is increased, the energy gap narrows. The gas sensor measurements showed that the resistivity of N- type gas sensor increases and return decreases by O2 Oxidization gas and the resistivity of P- type gas sensor decreases and return increase by O2 Oxidization gas but when NH3 reducing gas do opppsite behavior and the resistivity decreases by high operation temperature . The sensitivity of all the samples decreased with increasing of mixing ratio because decreases the surface area with increase the grain size. Keywords: Pure ZnO, 75%ZnO:25%SnO2, 50%ZnO:50%SnO2, Pure SnO2, P-type senso, n-type sensor