本研究報告了高性能半導體式氣體感測器的設計、製備與量測結果，旨在偵測關鍵氣體與揮發性有機化合物，包括氫氣、氨氣與甲醛。此研究採用射頻磁控濺鍍沉積之氧化銅薄膜作為基底，並於表面修飾具催化活性的鈀、鉑或金奈米顆粒，進而增強表面吸附與催化反應。本研究利用快速熱退火製程來改善元件的表面形貌與結晶度，經實驗結果證實，導入貴金屬奈米顆粒後，氣體感測器的靈敏度與選擇性顯著地提升了。
在第二章中，研究證實鈀奈米顆粒修飾氧化銅薄膜表面對氫氣有優異的催化活性。此修飾顯著增加了元件的有效感測面積，進而大幅提升感測性能。實驗結果顯示，在 275℃ 的最佳工作溫度與濃度為 1% 的氫氣環境下，感測響應可達 48.6，其反應時間與恢復時間分別為 179 秒與 23 秒。此外，該氣體感測器展現出卓越的偵測能力，氫氣的最低偵測極限低至 10 ppb，證實其具有高準確度的優異潛力。
在第三章中，研究證實鉑奈米顆粒修飾氧化銅薄膜表面對氨氣展現優異的催化活性。此修飾有效增加了元件的有效感測面積，進而增強感測性能。實驗結果指出，在 300℃ 的最佳溫度與濃度為 1000 ppm的氨氣環境下，感測響應達到 12.2，相應的反應與恢復時間分別為 249 秒與 47 秒。該元件對氨氣的最低偵測極限同樣低至 10 ppb，再次驗證其具備高靈敏度監測的可能性。
在第四章中，研究證實了金奈米顆粒對甲醛的催化作用。實驗證明，金奈米顆粒的修飾顯著提升了元件的有效感測面積與感測性能。在 300℃ 工作溫度與濃度為 20 ppm 的甲醛條件下，感測響應達到 169%，反應與恢復時間分別為 420 秒與 591 秒。此外，該氣體感測器對甲醛的最低偵測極限亦達 10 ppb，展現其於危害性氣體檢測的應用價值。
結論，本研究開發之氣體感測器均展現出卓越的感測能力，並具備體積小、製程簡易以及高成本效益等優勢。憑藉其快速的響應特性與高靈敏度，這些經催化金屬奈米顆粒修飾之氣體感測器，為環境與工業的安全問題提供了穩健的解決方案。

This study reports the design, fabrication, and comprehensive characterization of high-performance semiconductor-based gas sensors tailored for the detection of critical gases and volatile organic compounds (VOCs), including hydrogen (H2), ammonia (NH3), and formaldehyde (HCHO). The sensing platform utilizes a copper oxide (CuO) thin film deposited via RF magnetron sputtering as the matrix, which is further functionalized with catalytic palladium (Pd), platinum (Pt), or gold (Au) nanoparticles (NPs) to synergistically enhance surface adsorption and catalytic reactions. Rapid thermal annealing (RTA) was employed to optimize the interfacial morphology and crystallinity of the devices, while systematic kinetic analyses confirm that the incorporation of noble metal NPs significantly amplifies both sensitivity and selectivity.
In Chapter 2, the decoration of Pd NPs on the CuO thin film surface is demonstrated to provide superior catalytic activity toward H2. This functionalization significantly increases the effective surface area of the device, thereby markedly enhancing the sensing efficiency. Experimental results show that a high sensing response (SR) of 48.6 was achieved under exposure to 1% H2/air at an optimal temperature of 275℃, with corresponding response (recovery) times τa (τb) of 179 s (23 s). Furthermore, the sensor exhibited an exceptional detection capability for H2 concentrations as low as 10 ppb, confirming its outstanding limit of detection (LOD) and potential for high-precision gas monitoring.
In Chapter 3, the decoration of Pt NPs on the CuO thin film surface is demonstrated to provide superior catalytic activity toward NH3. This functionalization effectively expands the reactive surface area of the device, leading to a significant enhancement in sensing performance. Experimental results indicate that a high SR of 12.2 was achieved under exposure to 1000 ppm NH3/air at an optimal temperature of 300℃, with corresponding τa (τb) of 249 s (47 s). Furthermore, the device exhibited an exceptional detection capability for NH3 concentrations as low as 10 ppb, reconfirming its reliability as a high-sensitivity monitoring tool.
In Chapter 4, the research investigates the catalytic effect of Au NPs on HCHO detection. Experimental evidence confirms that the modification with Au NPs markedly improves both the device effective surface area and its sensing characteristics. At an operating temperature of 300℃ and under exposure to 20 ppm HCHO/air, the sensor reached an SR of 169%, with τa (τb) of 420 s (591 s). Additionally, the sensor demonstrated an exceptional LOD for HCHO at the 10 ppb level, underscoring its practical value for environmental gas monitoring.
Ultimately, each of the developed devices demonstrates exceptional sensing performance, characterized by a miniaturized footprint, facile fabrication process, and cost-effectiveness. Combined with their rapid recovery time and high sensitivity, these nanoparticle-functionalized sensors offer a robust and versatile solution for next-generation environmental sensing and industrial safety applications.

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