SYNTHESIS AND ETHANOL SENSING CHARACTERISTICS OF NANOSTRUCTURED MoO3:Zn THIN FILMS

Abstract

In this research, gas sensing characteristics of undoped and zinc-doped molybdenum trioxide (MoO[Formula: see text] thin films toward ethanol vapor were investigated. Thin films were deposited using low cost and simple technique of spray pyrolysis on top of glass substrates at 450[Formula: see text]C. Effects of addition of Zn, as an impurity, on the surface morphology, structural and optical properties of MoO3 thin films were also investigated. X-ray diffraction (XRD) pattern analysis showed that by increasing the amount of impurity, crystal structure changes from orthorhombic [Formula: see text]-MoO3 to two new phases of monoclinic [Formula: see text]-ZnMoO4 and Mo5O[Formula: see text] reduced phase. Field emission scanning electron microscope (FESEM) images showed that by increasing the amount of impurity up to 5[Formula: see text]at.%, grain sizes decrease to about 60[Formula: see text]nm. UV–Vis analysis showed that by increasing the percentage of impurity the band gap of thin films increases. Gas sensing properties of samples were studied at three temperatures of 200[Formula: see text]C, 250[Formula: see text]C and 300[Formula: see text]C toward different concentrations of ethanol vapor. Gas response of 5[Formula: see text]at.% Zn-doped MoO3 thin film reached the maximum value of [Formula: see text]% when it exposed to 1000[Formula: see text]ppm of ethanol vapor. Response and recovery times for all samples were reported at different temperatures.