| Summary: | 碩士 === 國立虎尾科技大學 === 電子工程系碩士班 === 104 === The Zinc Oxide (ZnO) have some advantages, including a wide direct bandgap of 3.37 eV, a high exciton binding energy with thermal stability at room temperature, and low cost. It is known that noble metal nanoparticles adsorption ZnO nanostructure can be increased field emission characteristics due to it can be provided electron for ZnO nanostructure. In this study, Ag nanoparticle adsorption ZnO nanosheets were successfully grown on glass substrates by the aqueous solution method and photochemical synthesis method. The as-prepared samples were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), transmission electron miscroscope (TEM) confirmed that Ag nanoparticle grown on the ZnO nanosheets. The CO2 sensing characteristics of pure ZnO and Ag nanoparticle-adsorption ZnO were compared using a gas sensing measurement system. The sensitivity, operating temperature, and response were systematically investigated based on the change in electrical resistance of the materials in the presence of CO2. It was found that the pure ZnO showed a maximum response to 1100 ppm CO2 (12%) at an operating temperature of 200℃. Experimental results confirmed that Ag nanoparticle- adsorption ZnO showed a maximum response to 1100 ppm CO2 (79%) at an operating temperature of 200℃. The results indicate that the Ag nanoparticle adsorption ZnO nanosheets exhibit enhanced gas sensing characteristics. The field emission characteristics of pure ZnO and Ag nanoparticle adsorption ZnO nanosheets are studied. It was found that the measured turn-on electric fields of the pure ZnO and Ag nanoparticle adsorption ZnO nanosheets were 5.3 and 3.2 V/μm, and the field enhancement factor were 3002 and 3420, respectively, in the dark. The measured turn-on electric fields of the pure ZnO and Ag nanoparticle adsorption ZnO nanosheets were 4.3 and 2 V/μm, and the field enhancement factor were 3276 and 4815 under UV illumination, respectively. The field emission performance of the Ag nanoparticle adsorption ZnO nanosheets were lower turn-on electric fields and larger β values than pure ZnO. The results indicate that the Ag nanoparticle adsorption ZnO nanosheets exhibit enhanced field emission characteristics.
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