本論文探討三維立體奈米樹狀結構的金屬氧化物堆疊式PNPN異質接面乙醇氣體感測器之研製。吾人先利用硝酸銀及氫氟酸之蝕刻溶液於P型(100)矽基板形成奈米柱結構，經由射頻濺鍍系統(RF Sputtering System)成長氧化鋅(ZnO)薄膜作為種晶層。透過水熱法(Hydrothermal Method)成長氧化鋅奈米線至矽奈米柱上，得到初步奈米樹結構。依序再濺鍍上氧化銅(CuO)與氧化鋅薄膜，藉由二次水熱法生長更多氧化鋅奈米樹分枝。完成Si-NR/ZnO-NW/CuO/ZnO-NW (PNPN)異質感測接面。最後再分別蒸鍍鋁金屬(Al)於異質接面上下方，作為金屬電極接觸層。
水熱法及蝕刻所製備的奈米結構因為具有較大的反應面積，能夠提升感測比值。吾人利用XRD及SEM分析薄膜的結晶情況，並觀察薄膜材料之表面結構與厚度，深入探討材料的基本特性以作為元件最佳實驗參數。本研究以不同矽蝕刻時間、不同ZnO種晶層濺鍍時間比較多組元件對乙醇之感測表現。
實驗結果顯示，Si/ZnO/CuO/ZnO全平面型元件在通入100ppm乙醇氣體之靈敏度僅有25%。而具有奈米樹狀結構之元件將靈敏度有效提升至90%，反應與回復時間分別縮短至16秒及40秒。奈米結構改善元件之體表面積比，大幅增進乙醇氣體感測能力。對於應用於工業安全及防止酒駕方面，有極大的潛力。

In this thesis, the PNPN heterojunctions with three-dimensional nanodendrite structure were developed for ethanol sensing applications. Firstly, the p-type silicon substrates were etched into nanorods structure by immersing in a mixture of chemical solution. The solution is composed of silver nitrate (AgNO3) and hydrofluoric acid (HF). Next, a zinc oxide (ZnO) film was deposited on the Si nanorods as a seed layer by RF sputtering system. Hydrothermal method was used immediately for growing ZnO nanowires. Copper oxide (CuO) and ZnO thin film were deposited sequentially also by sputtering on the surface of the ZnO nanowires. Once again, a second hydrothermal method was utilized to produce more branches of ZnO nanowires. Finally, the aluminum (Al) electrodes were deposited on the top and the bottom of the Si-NR/ZnO-NW/CuO/ZnO-NW (PNPN) heterojunctions to complete the sensing devices.
Nanodendrite structure has a larger response area, which can enhance the sensing ability. These structures were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM) for the crystallinity, morphology and thickness. The characteristics of the materials were analyzed and discussed for the optimal device parameters. Different etching times and different seed layer sputtering times were investigated for comparing their sensing performances.
According to the experimental results, the all planar device Si/ZnO/CuO/ZnO has only 25% of sensitivity. On the other hand, the device with nanodendrite structure is effectively raised to 90%. The response and recovery times are shortened to 16 s and 40 s, respectively. The large surface to volume ratio of the nanostructure enhances the sensing ability of the device to ethanol gas. It has a great potential for applying into industrial security and prevention of drunk driving.

目錄
論文審定書..............................................................................................ii
致謝.......................................................................................................iii
摘要.......................................................................................................iv
ABSTRACT.............................................................................................v
目錄 .....................................................................................................vii
圖目錄.....................................................................................................x
表目錄..................................................................................................xiv
第一章 緒論.............................................................................................1
1-1前言................................................................................................1
1-2氣體感測器 ......................................................................................1
1-3各金屬氧化物與乙醇氣體特性............................................................2
1-4論文架構…......................................................................................3
第二章 理論分析......................................................................................4
2-1氧化鋅水熱法生長機制......................................................................4
2-2矽奈米柱蝕刻理論與機制...................................................................4
2-3乙醇氣體感測器工作原理...................................................................5
2-4 PNPN乙醇感測器工作原理...............................................................7
2-5薄膜沉積機制...................................................................................8
2-5-1濺鍍機(Sputter)...........................................................................8
2-5-2蒸鍍機(Evaporator) ......................................................................9
2-6量測儀器原理...................................................................................9
2-6-1掃描電子顯微鏡(Scanning Electron Microscope，SEM)..................9
2-6-2 X光繞射儀(X-ray diffractometer，XRD).......................................11
2-6-3乙醇氣體量測 .............................................................................11
第三章 實驗方法與流程............................................................................13
3-1初始原料選用...................................................................................13
3-2氣體感測器生長系統.........................................................................14
3-2-1射頻濺鍍系統 ..............................................................................14
3-2-2蒸鍍系統.....................................................................................15
3-3氣體感測器量測系統 .........................................................................15
3-4製程步驟與成長參數..........................................................................16
3-4-1基板清洗.....................................................................................17
3-4-2矽奈米柱蝕刻 ..............................................................................17
3-4-3氧化鋅薄膜種子層濺鍍沉積...........................................................17
3-4-4水熱法生長氧化鋅奈米結構...........................................................17
3-4-5氧化銅薄膜與氧化鋅薄膜濺鍍沉積.................................................18
3-4-6再次水熱法生長氧化鋅奈米結構....................................................18
3-4-7蒸鍍系統沉積鋁電極....................................................................18
第四章 結果與討論...................................................................................20
4-1薄膜特性分析...................................................................................20
4-1-1氧化鋅水熱法生長結果.................................................................20
4-1-2矽奈米柱蝕刻結果........................................................................20
4-1-3矽奈米柱上生長氧化鋅奈米線........................................................21
4-1-4矽奈米柱/氧化鋅奈米線上濺鍍氧化銅.............................................22
4-1-5矽奈米柱/氧化鋅奈米線/氧化銅/氧化鋅奈米線.................................22
4-2以再次水熱生長氧化鋅奈米結構.........................................................23
4-3矽晶片上生長氧化鋅奈米片...............................................................23
4-4元件電性量測...................................................................................24
4-4-1矽/氧化鋅/氧化銅/氧化鋅堆疊之平面與奈米結構比較.......................24
4-4-2以矽蝕刻時間作為參數製成PNPN元件對乙醇氣體電性量測..............25
4-5性能最佳元件之動態響應圖與選擇性比較............................................26
第五章 結論與未來展望.............................................................................28
參考文獻.................................................................................................29
附圖........................................................................................................32
附表........................................................................................................79

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