| Summary: | 碩士 === 國立臺灣師範大學 === 機電工程學系 === 103 === In this study, the ZnO nanowires are prepared on glass substrate by using hydrothermal method, and deposited BiFeO thin film on the ZnO nanowires by sputtering; later, comparing the sensitivity of the pure ZnO nanowires and the ZnO nanowires with BiFeO. Different thickness of ZnO seed layer can be obtained by changing the sputtering deposition power, so with the increase of the thickness of seed layer, the surface roughness is reduced, and its nanowires diameter and length will be reduced. Using a hydrothermal method prepares ZnO nanowires of three kind of thickness 27, 35 and, 45 nm, and conducts gas sensing experiment of acetone and ammonia at 100, 150 and 200 °C, respectively. The seed layer thickness of 35 nm grown ZnO nanowires have the best sensing sensitivity (S = 7.2 for acetone, S = 3.72 for ammonia). After that we adopt the surface modification process to deposit the bismuth ferrites thin film coated on ZnO nanowires to increase gas sensitivity, and we find that the BiFeO thin film on ZnO nanowires of sensing sensitivity has been improved (S = 7.41 for acetone, S = 4.61 for ammonia), and ammonia sensing sensitivity are increased when operating temperature increases. Finally, conduct gas sensing experiment of high-temperature (300 °C) and room temperature (25 °C) ammonia, and the response speed is proportional to the concentrations of ammonia, especially BiFeO thin film coated on ZnO nanowires, With the concentrations increase, the response is also increase, even at low concentrations (1 ppm) also have the same result.
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