Elaboration et caractérisation des matériaux en couches minces d’oxydes de zinc pour applications capteurs

Abstract

This work focuses on the study, development and characterization of thin film materials based on zinc oxide for use sensing application. Those films were elaborated using sol gel technique associated to dip and spin coating. At first it sets out general notions about gas sensing and the different types of chemical sensors based on metal oxide. A presentation of the sol-gel process will be discussed. The Properties of gas and humidity sensing of ZnO thin films will be dealt with illustrations and discussions of surface phenomena. The mounting manipulations ensuring filing procedures and The steps of developing thin film ZnO include all phases of preparation will be exhibited. After the phase of the preparation, characterization were performed on the samples of pure and Sn doped ZnO.A comparative study has been carried out between films elaborated by spincoating and films elaborated by . For the tests of relative humidity both sensors show an obvious change in the impedance with respect to Rh%. The effect of the operating temperature was also studied. The Sn doping effect on ZnO films was also studied. Characterisation XRD showedthat the intensity of the XRD peaks decreases with increasing concentrations of Sn.AFM images showed that the surface morphologies of the films are dependent on dopant concentration.To study the properties of the reaction of the sensor based on ZnO films to humidity and volatile gas of ethanol. we investigated the change in sensor resistance at different relative humidity environments and at different concentrations of ethanol gaz. The corresponding resistance decreases with increase of the relative humidity (RH%) for different doping levels of Sn. The sensor based on ZnO doped with Sn to 5% this much linearity with high sensitivity to moisture. It is indicated that the zinc oxide film doped with tin have a high sensitivity in these gas detection experiments.