Study On Fabrication And Gas Sensing Properties Of Zinc Oxide Nanostructureed Surface Acoustic Wave(SAW) Sensors

Using the nanostructure films as the sensitive structure of surface acoustic wave sensors is a hot spot in the research of surface acoustic wave sensors.Zinc Oxide has good piezoelectric properties,UV absorption and fluorescence characteristics,and ZnO has good application in gas detection and UV test.Zinc Oxide nanostructure is of great research value among the oxide nanomaterials.In this thesis,the preparation and characteristic of pure ZnO nanostructure are investigated.AFM,SEM,XRD and transmittance were employed to characterize ZnO nanostructure.And the surface acoustic wave sensors based on the ZnO nanostructure were fabricated for gas sensing characteristics and UV characteristics detection.The main works of the experiment include:1.ZnO nanofilms were fabricated,and the ZnO films were characterized via AFM,XRD,SEM and light transmittance;surface acoustic wave sensor based on the nanostructure was prepared.And gas sensing and UV characteristics of the sensor were studied.In the experiment,the sensor could detect ammonia with a good respose when the concentration was 10 ppm and detect ultraviolet with wavelength of 365 nm when the radiation intensity was only 6 μw/cm~2.The effects on the ZnO thin films prepared via sol-gel were studied which from the solvent concentration,the concentration of zinc acetate and the sintering time.The Zn O thin film surface acoustic wave sensor with positive response variation was found.2.Using polyimide tape to cover the interdigital transducers,reflectors and a portion of sensitive areas,ZnO nanorods array could cover only a portion of sensitive area.The Zn O nanorods array were characterized via XRD、SEM and transmittance.Surface acoustic wave sensors based on ZnO nanrods were used to detect gas sensing and UV sensing.The ZnO nanorods array with no seed layer was prepared and characterized by SEM and XRD.The surface acoustic wave sensor based this ZnO nanorods array was fabricated to detect the gas sensing.Two kinds of sensors have achieved good results in gas sensing test,both observed a response more than 100 Hz under 10 ppm ammonia.Surface acoustic wave sensor based on the ZnO nanorods which covered postion of seed layer made a response of 200 Hz when exposed to the UV radiation intensity of 6 μw/cm~2.3.Nano ZnS structure was prepared,and the nanostructure was characterized by SEM and XRD.Surface acoustic wave sensor based on ZnS nanosheets was prepared.And the gas sensing characteristics was investigated.The sensor showed good selectivity to ammonia,and the sensor made a response of 170 Hz when the ammonia concentration was 1 ppm.