本實驗製作銅氧化物/金/氧化鋅奈米線複合材料，並應用於二氧化氮氣體感測。首先利用黃光微影與電子束蒸鍍技術，形成鈦金屬電極於矽晶圓上，然後以低溫水熱法成長氧化鋅奈米線於矽晶圓基板，並對氧化鋅奈米線進行高溫退火，再藉由簡單方便的光還原法，添加銅氧化物與金顆粒至氧化鋅奈米線，形成一具有貴金屬、金屬氧化物與氧化鋅基材的三元複合材料。以此複合材料進行二氧化氮氣體感測，當氣體分子化學吸附於複合材料表面會搶奪電子，造成電阻增加，因此可由電阻變化率得知氣體濃度。
　　藉由掃描式電子顯微鏡觀察材料的表面形貌，以硫酸銅水溶液光還原製作的銅氧化物氧化鋅，在奈米線的頂端或側壁會出現表面平滑的立方狀顆粒物，尺寸約為數百奈米；而以四氯金酸水溶液光還原製作的金/氧化鋅則具有表面粗糙的球狀顆粒物。若依序進行上述兩種光還原法，金/銅氧化物/氧化鋅複合材料可發現金披覆銅氧化物的顆粒物；而銅氧化物/金/氧化鋅複合材料則呈現細小顆粒物均勻散布的現象。
　　以紫外光激活模式對材料進行NO2氣體感測，對於100 ppb的NO2，氧化鋅奈米線具有22%的平均響應。銅氧化物/氧化鋅複合材料的平均響應提高至211%，推測是因p-型銅氧化物與n-型氧化鋅接合形成p-n 接面，在氧化鋅內部形成空乏區而使響應增加；另一方面，金/氧化鋅複合材料平均響應也提高到239%，推論是由於金為吸附觸媒，可增加NO2的吸附量而使響應增加。
　　對於三元複合材料，對100 ppb NO2，金/銅氧化物/氧化鋅複合材料的平均響應降至81%，這樣的原因推論為金與銅氧化物間的接觸並不如金與氧化鋅，使得氣體從銅氧化物搶奪電子的過程受到阻礙而形成響應減低的現象；而銅氧化物/金/氧化鋅複合材料則具有最高的283%平均響應，推論因其細小的添加物與氣體分子之間具有較大的接觸面積，使添加物的效果達到最大。
　　綜合以上，銅氧化物/金/氧化鋅的結構可以具有最高響應，並且本實驗製作之三元複合材料具有比單一基材高上12.8倍的二氧化氮氣體感測響應，應對於低濃度二氧化氮的感測能力極具潛力。

　　In this work, we produced copper oxide/gold/zinc oxide nanowire composites and applied to NO2 gas sensing. First of all, we formed titanium electrodes on silicon wafers by photolithography and e-beam evaporation techniques. Second, zinc oxide nanowires were grown by low-temperature hydrothermal method and were annealed. Further, a simple and convenient photoreduction method was utilized to add copper oxide and gold particles on the nanowires. Then, ternary composites which contained a noble metal, a metal oxide and the zinc oxide matrix were made. Lastly, the composites were experimented in NO2 gas sensing. When NO2 chemically adsorbed on the composite surface, NO2 will trap the electrons and result in resistance increase. Based on the change in resistance, we can infer the gas concentration.
　　We used scanning electron microscopy to observe the morphologies of materials. CuXO/ZnO produced by Copper Sulfate (CuSO4) photoreduction showed some smooth, cubic particles with a diameter of hundreds of nanometers on the nanowire surface, and Au/ZnO produced by Chloroauric acid (HAuCl4) photoreduction appeared rough, spherical particles with non-uniform sizes. If successively proceeded the two photoreductions mentioned above, some particles with an Au-covered CuXO structure were discovered on Au/CuXO/ZnO composite. However, many fine and smooth particles were dispersed uniformly on the surface of CuXO/Au/ZnO composite.
　　We realized the NO2 gas sensing experiment under UV-activation mode for all materials mentioned. For 100 ppb NO2, the ZnO nanowires excited a 22% of average response. Comparatively, the CuXO/ZnO composite had an enhanced average response, of 211%. The reason might be the formation of depletion layer in the ZnO resulted from p-n junction between CuXO and ZnO. On the other hand, the Au/ZnO composite also showed an average response of 239%. It was inferred that gold can catalyze adsorption and enhance the number of adsorbed NO2 molecules.
　　Regarding ternary composites, for 100 ppb NO2, the average response of Au/CuXO/ZnO composite decreased to 81%. One potential reason might be that the contact between Au and CuXO wasn’t as good as the one between Au and ZnO and would interfere electron transfer. On the contrary, the CuXO/Au/ZnO composite revealed the highest 283% average response. It might be attributed to the large contact area between additives and NO2 gas provided by those finer additives.
　　In conclusion, CuXO/Au/ZnO structure can maximize the NO2 response. Also, this ternary composite showed a 12.8 times higher NO2 response than single material. This indicates it has potential applicaiton for low concentration NO2 gas sensing.

中文摘要 II
Abstract　 III
致謝　　 IV
總目錄　 V
圖目錄　 VIII
表目錄　 X
Chapter 1緒論 1
1.1 前言 2
1.2 研究動機 3
Chapter 2文獻回顧 4
2.1 氧化鋅概論 5
2.1.1 氧化鋅晶體結構 5
2.1.2 氧空缺本質摻雜 5
2.1.3 氧化鋅光學性質 7
2.1.4 奈米線合成方法與機制 8
2.2 氣體感測原理 11
2.2.1 金屬氧化物之氣體感測機制 11
2.2.2 二氧化氮與氧化鋅的吸附反應 12
2.2.3 紫外光激活之回復特性 12
2.3 金屬氧化物複合材料之氣體感測應用 15
2.4 光還原法 17
Chapter 3實驗流程與儀器 20
3.1 材料製作流程 21
3.1.1 電極製作 21
3.1.2 氧化鋅奈米線成長 22
3.1.3 退火處理 23
3.1.4 添加物的生成 23
3.2 材料分析儀器 24
3.2.1 掃描式電子顯微鏡 24
3.3.2 能量色散X射線光譜 25
3.3.3 X-射線繞射分析儀 25
3.2.4 螢光光譜儀 25
3.3 氣體感測實驗 25
3.3.1 氣體感測系統 25
3.3.2 二氧化氮濃度計算 26
3.3.3 氣體感測操作流程 27
Chapter 4實驗結果與討論 28
4.1 材料分析 29
4.1.1 表面形貌 29
4.1.2 晶體結構與元素組成 35
4.1.3 光致放光性質 38
4.2 二氧化氮氣體感測結果 40
4.2.1 大氣退火處理對氣體感測的影響 40
4.2.2 銅氧化物/氧化鋅二元複合材料的感測結果 42
4.2.3 金/氧化鋅二元複合材料的感測結果 45
4.2.4 三元複合材料的感測結果 46
4.2.5 無退火之三元複合材料的感測結果 48
Chapter 5 53
參考文獻 56

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