| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 96 === This thesis consists of two parts.In part one,Spray pyrolysis and Hydrothermal method are used to deposit the ZnO thin film and the ZnO nanorod,respectively. In part two,gas sensors based onboth type of ZnO are used to detect NO2 and NH3 gas. This study is focused on the effect of ZnO morphology on its sensing property.
In terms of sensing NO2 gas,the sensing mechanism was directly capturing the electrons from the conduction band and the conductivity was lowering.So,the changes of conductivity of NO2 gas sensing was related to the suface area or the height of the nanorods. In terms of sensing NH3 gas,however,the gas reacted with the oxygen ion on the surface of the ZnO,and the oxygen ion came from the defects of ZnO. So,we used the Photoluminescence to measured the changes of the different diameter of the nanorods. As it turn out,the change of conductivity was the highest when the Hydrothermal concentration was 0.05M(diameter is about 70nm). So,the gas sensing ability of NH3 gas was not corresponded to the surface area of nanorods.but the inherence of defects of ZnO .
Furthermore，we annealed the nanorods in the N2 atmosphere.When the annealing temperature is higher,the intensity of visible light in Photoluminescence is gradually lower and the intensity of UV light is getting higher. This phenomenon is because that when we anneal the nanorods the defects are reduced,and the crystal property is getting perfect.However,gas sensor property is favored of nanorods with more defects.
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