臺灣博碩士論文加值系統

摘 要
隨著光電產業的快速發展，各種材料不斷被開發，而透明導電膜是近年來LCD為首的平面顯示器(FPD)產業應用最多的新材料，所謂的透明導電膜是指高導電性、高可見光穿透率的薄膜材料，而具異價添加劑的氧化鋅(ZnO)是目前最具潛力的透明導電膜材料。藉由添加異價添加劑及氣氛熱處理，可有效提升自由電子的濃度，進而提高氧化鋅(ZnO)導電率。因此，本研究以不同濃度的Ti添加至ZnO基材中，經由後續氣氛熱處理，以探討Ti離子添加及氣氛熱處理對ZnO晶體結構及導電性質之影響。
本研究利用固相反應法，將ZnO及TiO2粉末經球磨混合均勻，加熱至1000℃進行鍛燒，鍛燒後之粉末，經二次球磨後，壓製成圓餅狀試片，並在大氣氣氛 及低氧分壓 下，1400℃高溫燒結6小時。鍛燒後或燒結後之試片，經XRD繞射分析決定其晶體結構並分析其晶格常數，部份燒結試片，則在兩側塗以白金電極進行導電率量測且利用SEM觀察其顯微結構組織。此外，部份在大氣中燒結之試片，再經由氫氣氣氛 500℃熱處理5小時，並觀察其晶體結構、晶格常數及導電性質之變化。
鍍膜的製備是利用射頻磁控濺鍍法（RF magnetic sputtering），於康寧1737F玻璃上，成長透明的Ti-doped ZnO薄膜，並經由不同氣氛（大氣: ╱低氧分壓: ╱氫氣: ）500℃熱處理1小時，求取製程最佳化條件，同時探討Ti-doped ZnO薄膜之材料特性與光學性質。
研究結果顯示，Ti-doped ZnO塊材在大氣氣氛 燒結下，ZnO中Ti離子固溶量最大可達1.0at%，並隨著TiO2的添加，會生成第二相Zn2TiO4。在1.5at% Ti-doped ZnO中，Zn2TiO4体積分率達10.5%。由XRD分析，也發現ZnO的晶格常數隨離子半徑較小Ti離子之添加逐漸減小，undoped ZnO其a軸為3.256 Å、c軸為5.209Å，但1.0at% Ti-doped ZnO，其a、c軸則分別降低為3.252 Å、5.202Å。當Ti的添加量超過固溶極限，Zn2TiO4第二相形成，ZnO中的Ti含量應維持不變，其晶格常數也達一定值。在低氧分壓 下合成之試片，XRD結果發現Ti離子的固溶度可達1.5at%，高於大氣下合成之試片，其原因可以下列缺陷方程式加以說明。
TiO2 Ti··Zn＋OXO＋ O2＋2e’
在還原氣氛下，有利於反應向右側進行，因此有助Ti離子固溶度之提升。在導電率方面，由上式可預期，自由電子濃度隨著Ti離子固溶量的增加而增加，在大氣 下合成之undoped ZnO，導電率為5.67×10-7 S/cm，當Ti離子添加量為1.0at%時，其導電率提升為1.2×10-6 S/cm。在氫氣 下熱處理之試片，因氧空缺的形成及Ti離子固溶度的增加，對undoped及Ti-doped ZnO其導電率皆由5.67×10-7、1.2×10-6 S/cm提升為4.15×10-2、 2.24×10-1 S/cm。
經磁控濺鍍薄膜化之Ti-doped ZnO鍍膜經氣氛熱處理後皆有明顯的(0002)面擇優取向，表面平整緻密，鍍膜之結晶性改善；Ti-doped ZnO薄膜經還原氣氛熱處理，皆可以明顯觀察到柱狀晶結構。Ti離子的添加以及氫氣 氣氛熱處理可有效提升Ti-doped ZnO鍍膜之導電性，Ti-doped ZnO鍍膜經由500℃氫氣 氣氛熱處理一小時，可得到最高導電率為4.7×10２S/cm。Ti-doped ZnO之薄膜與燒結試片經氫氣 氣氛熱處理後，所量得導電率之差異原因乃在於，在氫氣 下熱處理之試片，僅表面層(厚度約為1μm)產生還原效應，而薄膜試片則可達到完全還原熱處理的效果。經氣氛熱處理之Ti-doped ZnO薄膜其平均透光率皆可達80∼85%。

Abstract
Zinc oxide (ZnO) has been commonly used as the transparent conducting thin films because of its high electrical conductivity and optical transparency properties. The addition of aliovalent dopants has been recognized as an ideal method to enchance electrical properties of ZnO. With addition of aliovalent dopants and atmosphere treatment, the free electrons concentration and the conductivity in doped ZnO can be enhanced.
The objective of this work was to study the effect of aliovalent dopant and atmosphere treatment on the structure and conductivity for ZnO.
The results of this work show that the defects structure and electrical properties of ZnO were significantly affected by aliovalent dopant due to the charge compensation and atmosphere treatment.
When Ti-doped ZnO were sintered in air , the solubility limit of Ti ion reached 1.0at%. With the addition of more than 2.0at% TiO2, the second phase (Zn2TiO4) was found. Within the solubility limit, the concentrations of free electrons increased with the addition of Ti ions. The conductivity of undoped ZnO was found to be 5.67×10-7 S/cm. The conductivity of 1.0at% Ti-doped ZnO sintered sample was 1.2×10-6 S/cm. The conductivity of the Ti-doped ZnO, however, decrease with the addition of the second phase (Zn2TiO4). The conductivity of 33.3.at% Ti-doped ZnO bulk was 3.38×10-7 S/cm. Under reducing atmosphere treatment, the conductivity and solubility limit of Ti-doped ZnO were enhanced. These results were discussed in light of defect reaction. The conductivities for undoped and 1.5at% Ti-doped ZnO were 4.15×10-2 and 2.24×10-1 S/cm. The solubility limit of TiO2 was extended to 1.5at%.
RF sputtered ZnO thin films were also examined. Ti-doped ZnO thin films show (002) preferred orientation. Under H2 treatment at 500℃ for 1 hour, 1.0at% Ti-doped ZnO thin films exhibits a high conductivity of 4.7×10２S/cm. The high transmittance of 80~85% was also obtain from 1.0at% Ti-doped ZnO.

總目錄
摘要……………………………………………………………………Ⅰ
Abstract………………………………………………………………Ⅳ
總目錄…………………………………………………………………Ⅵ
圖目錄…………………………………………………………………VI
表目錄…………………………………………………………………VI
第一章 緒 論…………………………………………………………1
1-1 透明導電膜………………………………………………………1
1-2 透明導電膜之應用………………………………………………2
1-3 透明導電膜之製備………………………………………………2
1-4 研究動機與目的…………………………………………………3
第二章 理論基礎……………………………………………………6
2-1 ZnO晶體結構及特性……………………………………………6
2-2 粉末治金燒結原理……………………………………………8
2-3-1 薄膜沉積成長理論…………………………………………10
2-3-2 薄膜表面及截面形態結構…………………………………13
2-4 濺射原理………………………………………………………15
2-4-1 電漿反應……………………………………………………15
2-4-2 濺鍍機構……………………………………………………19
第三章 實驗方法與步驟……………………………………………24
3-1 Ti-doped ZnO塊材的實驗流程…………………………………24
3-1-1 氧化鋅（ZnO）和氧化鈦（TiO2）粉末的合成……………24
3-1-2 粉末之成型與燒結…………………………………………27
3-1-3 試片的氣氛熱處理…………………………………………27
3-1-4 導電率測試…………………………………………………29
3-1-5 X光繞射分析…………………………………………………29
3-1-5-1 結構分析………………………………………………29
3-1-5-2 晶格常數測定…………………………………………31
3-1-6 SEM表面觀察……………………………………………31
3-1-7 EDS成份分析………………………………………………32
3-2 Ti-doped ZnO薄膜的實驗流程…………………………………32
3-2-1 濺鍍系統說明………………………………………………32
3-2-2 材料準備……………………………………………………36
3-2-3 基材準備與清洗……………………………………………37
3-2-4 薄膜濺鍍及熱處理條件參數………………………………37
3-2-5 性質測試與分析……………………………………………37
第四章 結果與討論…………………………………………………45
4-1 TiO2的添加對ZnO塊材（bulks）之晶體結構與導電性質的影響………45
4-1-1 Ti-doped ZnO 晶體結構分析…………………………45
4-1-2 Ti-doped ZnO 導電性質分析…………………………54
4-1-3 Ti-doped ZnO 顯微結構分析…………………………56
4-1-4 氣氛對Ti-doped ZnO塊材晶體結構與導電性質之影響…61
4-2 TiO2的添加對ZnO薄膜(thin film)之晶體結構與導電性質的影響...75
4-2-1 結晶結構分析………………………………………………76
4-2-2 顯微結構觀察………………………………………………85
4-2-3 電性分析……………………………………………………89
4-2-4 光學性質……………………………………………………96
第五章 結 論………………………………………………………102
第六章 參考文獻……………………………………………………105
附錄…………………………………………………………………109
誌謝…………………………………………………………………110

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