隨著工業科技的發展，人們的日常生活充斥著越來越多的工業產品，在外在或室內環境中，皆有可能釋放出揮發性有機混合氣體，而大部分暴露在人們周遭的揮發有機氣體，當濃度達到一定程度時，會對人體健康造成傷害。因此，氣體感測器也漸漸地成為人們關注的焦點。現今，金屬氧化物半導體式氣體感測器已引起人們濃厚興趣，由於它具簡單操作、低成本、製作一致性與即時應用的高可靠度。另外，對氧化物半導體來說，具有高靈敏度、快的偵測速度且良好選擇性是三項最重要的特性。氧化鋁鋅氣體感測器具有環境友善、低成本、良好一致性、好的選擇性、高靈敏度、高導電度等等優點。因此，本論文將以氧化鋁鋅作為氣體感測之材料，並藉由X光薄膜繞射分析儀、原子力顯微鏡、掃描式電子顯微鏡、能量分散式光譜儀、傅立葉轉換紅外光譜儀來分析氧化鋁鋅薄膜之結構、表面型態、元素組成和鍵結。
在元件製程方面，首先，吾人利用熱蒸鍍法製作鉻/鉑的指叉式電極於藍寶石基板上，接著以射頻磁控濺鍍法製備氧化鋁鋅感測薄膜，最後以快速熱退火增加氧化鋁鋅的結晶性，並針對各種不同濃度的氣體進行氣體感測分析。
其次，吾人以不同催化金屬結合氧化鋁鋅感測薄膜，改善金屬氧化物系感測器之選擇性問題。吾人以鈀和鉑金屬薄膜催化氫氣與氨氣，實驗結果，經過修飾後的氧化鋁鋅薄膜分別顯示對氫氣與氨氣均有良好的感測能力。
最後，吾人將金奈米顆粒以濕式沉積於氧化鋁鋅薄膜結構上。金奈米顆粒對甲醛是一個良好的催化劑並形成更多吸附座，有著更大的表面積，促進氣體在材料表面傳送和反應，因此，添加金奈米粒子確實提升了靈敏度，使得甲醛感測性能大幅改進。

With the development of industry, people's daily life is full of more and more industrial products, which can release volatile organic compounds (VOCs) in indoor air. Most of the VOCs, which are exposed to people for some time, pose a threat to human health when the concentration reaches a certain degree. Therefore, people also gradually focused on gas sensors. Nowadays, gas sensors based on metal oxide semiconductor materials have attracted increasing interests, due to their simple implementation, low cost, high compatibility with semiconductor processing and good reliability for real-time applications. Furthermore, it is well known that high sensitivity, rapid response, and excellent selectivity are three most important properties for oxide semiconductor gas sensors. Aluminum-doped zinc oxide (AZO) based gas sensors have its merits, such as environmental friendliness, low cost, good compatibility, excellent selectivity, high sensitivity and so on. Consequently, Aluminum-doped zinc oxide (AZO) was employed as gas sensors in this study and analyzed its compositions, structures and atomic bonding by x-ray diffractometer (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and fourier transform infrared spectroscopy (FT-IR).
First, the Cr/Pt interdigitated electrodes were fabricated on a sapphire substrate by thermal evaporation. Then, the AZO sensing layer was deposited by radio-frequency (RF) sputtering. Finally, the crystalline of AZO was improved by rapid thermal annealing (RTA) and gas sensing properties were discussed.
However, the normal nickel oxide gas sensor had bad selectivity on the different gas concentration. So that, we utilized different catalytic metal which could induce selectivity to composite AZO film. Then, palladium and platinum catalytic metal film by thermal evaporation could effectively catalytic hydrogen and ammonia gas. The result, both hydrogen and ammonia gas had excessive sensing property.
Finally, Au nanoparticles were deposited on the AZO sensing film structure. Au nanoparticles were excellent catalyst for formaldehyde and formed more active sites and structures with large surface area that facilitated gas transmission and reaction on the surface of the materials. Thus, the addition of Au nanoparticles actually enhances the sensitivity and improves formaldehyde sensing property.

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