| Summary: | 碩士 === 國立交通大學 === 照明與能源光電研究所 === 107 === In this study, SnO2 films and SnO2-TiO2 composite films were fabricated by atomic layer deposition. The hydrogen and alcohol gas sensing properties of the fabricated films were investigated. It was found that the hydrogen and alcohol sensing ability of SnO2-TiO2 composite films can be improved by ultrasonic cleaning with a sequence of acetone, methanol and DI water. After post cleaning, the gas sensing temperature was lowered and the gas sensing response was enhanced.
For SnO2 films with stable film resistance, it was found that the thinner the thickness the better the sensing sensitivity. However, if the film is too thin, the film resistance rises seriously when exposed to atmospheric environment, resulting in deterioration of gas sensing response. In terms of film stability and gas sensing performance, the suitable deposition temperature for SnO2 films is 300 °C, followed by 400 °C, and then 450 °C.
For SnO2-TiO2 composite films with 30-nm 300 oC deposited SnO2, it was found that the 20-cycle ALD TiO2 overcoat layer performs the best for sensing hydrogen and alcohol. As the cycle number of ALD TiO2 deviates from 20, the sensing sensitivity of the SnO2-TiO2 composite films decreases. And sensitivity of the composite films is dominated by the TiO2 layer.
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