本論文主要研究二氧化錫(SnO2)/三氧化鎢(WO3)複合式奈米球之NOx氣體感測器，有別於一般單使用二氧化錫為感測層，因三氧化鎢材料對於二氧化氮(NO2)有良好的感測性質，可以克服NOx易受環境影響使得氣體在NO與NO2間轉換，造成感測器之穩定性受到干擾與衰減感測之情況。與傳統薄膜式氣體感測器相比，本研究藉由二氧化錫奈米球與三氧化鎢奈米球堆疊可以大幅提升感測表面積，並搭配催化金屬增加氣體反應靈敏度，以及利用矽基微加熱器作為感測器基板，可使元件操作於最佳工作溫度，研究不同二氧化錫奈米球與三氧化鎢奈米球混合比例及奈米球感測層進行不同溫度熱處理對氣體感測器之影響。
本論文首先研究具單一奈米球結構感測層的氣體感測器，元件操作溫度為100 oC，以單一結構二氧化錫奈米球作為感測層時的氣體感測元件之響應度(Rg/Ra)於900、700、500及300 ppb一氧化氮濃度氣氛下分別為1.35、1.24、1.16及1.06。另以最佳比例0.25:1(重量比)的三氧化鎢與二氧化錫複合奈米球作為氣體感測器之感測層，以500 oC鍛燒處理此複合奈米球感測層，並使用薄金(Au)作為催化金屬，具金催化金屬之複合奈米球氣體感測器元件在操作溫度為250 oC下，於700、500、300及200 ppb一氧化氮濃度中，元件的響應度分別為1.77、1.56、1.31與1.20。實驗結果顯示，具複合式奈米球結構之感測器，無論響應度或量測極限皆明顯高於單一奈米球元件量測之結果，說明利用複合式奈米球結構所製作之氣體感測器不僅可有效改善感測響應特性，更可提升元件的量測極限濃度值達200 ppb。本實驗所開發之感測元件技術具有低成本高感度的優勢，同時亦具有低感測極限，未來可望應用至氣體感測相關元件之開發與應用。

In this study, the layers of WO3/SnO2 complex nanoparticles, instead of pure SnO2 or WO3, were applied for sensing nitrogen oxide (NO) gas. the gas sensors with WO3:SnO2 (0.25:1) complex nanoparticle sensing layer in order to overcome the environmental impact of gas sensors, because the NO gas is easily reacted to form NO2 gas, the resulting NO gas sensors are seriously affected and degraded. Furthermore, by performing an annealing process at 500°C and then depositing a gold (Au) catalytic metal layer on the annealed WO3/SnO2 complex nanoparticles, the resulting NO gas sensors exhibited the sensing response of 1.77, 1.56, 1.31 and 1.20 under the NO gas concentration of 700 ppb, 500 ppb, 300 ppb, and 200 ppb, respectively. Moreover, the lowest detection limit of the NO gas sensors with Au covered WO3:SnO2 (0.25:1) complex nanoparticle sensing layer was also extended from 300 to 200 ppb compared with the NO gas sensors with pure SnO2 nanoparticle sensing layer.

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