本論文探討利用玻璃基板上準分子雷射退火(Excimer Laser Annealing)成長的低溫多晶矽薄膜(LTPS) 製作不同結構ZnO，SnO2及WO3 為 感 測 元件的MIS蕭特基二極體式一氧化碳感測器。吾人利用水熱法(hydrothermal method)製備ZnO奈米柱、SnO2奈米多孔薄膜、SnO2奈米微粒子以及SnO2奈米花並研究不同奈米結構對一氧化碳感測器之影響。
研究分為三個部分，(1)不同感測材料ZnO、SnO2、以及WO3之比較(2)採用不同厚度種晶層成長ZnO奈米柱並與ZnO薄膜相互比較(3)利用不同時間對種晶層退火成長SnO2不同表面形態之奈米結構並與SnO2薄膜相互比較。
實驗結果顯示，在200℃，逆偏壓3V及3000ppm的CO +air的環境下WO3薄膜對一氧化碳氣體的感測能力約為320%；SnO2薄膜為220%; ZnO薄膜為66%。但如成長為奈米結構則ZnO奈米柱為615%；SnO2奈米花(nano flower)有最佳之感測能力靈敏度約3520%。而對小濃度(100ppm)的一氧化碳感測以WO3薄膜的72%與SnO2奈米花的128%為最佳。相較已發表於文獻在270℃/100ppm 條件下Au/SnO2 電阻式的8%及Au/ZnO/(n-type Si)i電子式的37%感測器為佳。
另外，吾人也探討不同結構感測層對反應時間的影響。在逆偏壓3V，200℃及100ppm的CO +air的環境下的反應時間，其中以SnO2奈米花有最快的反應時間12sec；其次WO3薄膜為16sec；最後則是ZnO奈米柱的22sec。這些也都比Au/SnO2電阻式的470sec及Au/ZnO/(n-type Si)電子式的173sec來的快。

In this thesis, we use the excimer laser annealing(ELA) prepared　 low temperature poly-silicon thin film(LTPS) with various structure metal oxide (MOx) on glass substrate to fabricate the MOS Schottky diode-type CO gas sensor. The various structure MOx are ZnO nanorods, SnO2 nano porous, SnO2 nano particle and SnO2 nano flower using hydrothermal method.
We report the comparisons in sensing characteristics for (a) different sensing material ZnO, SnO2, and WO3, (b) the grown ZnO nanorods with different seed layer thickness, and (c) the grown SnO2 nanostructure with different annealing time.
Experimental results showed the Schottky diode with ZnO nanorods and SnO2 nano flower can achieve sensitivity up to 615% and 3520% under 200℃ ,3V reverse bias, and 3000ppm CO /air ambient, respectively. For detecting a small concentration CO gas, WO3 thin film and SnO2 nano flower have the best sensing abilities of 72% and 128%, respectively. These sensitivities are better than the reported 8% and xxx 37% under 270℃/100 ppm for the Au/SnO2 resistance and Au/ZnO/(n-type Si) electronic type sensors, respectively.
Furthermore, we also discussed the influences of sensing layers with different structures on the response time. Under the conditions of reverse bias 3V, 200℃ and 100ppm of CO / air environment, the response time of the sensors with SnO2 nano flower, WO3 thin film and ZnO nanorods are 12sec, 16sec, and 22sec, respectively. Obviously, the SnO2 nano flower has the best response time, and fast than 470sec and 173sec of the reported Au/SnO2 resistance and Au/ZnO/(n-type Si) electronic type sensors, respectively.

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