本論文主要利用冷壁式有機金屬化學氣相沉積法 (Cold-wall metal organic chemical vapor deposition, MOCVD) 製備銳鈦礦二氧化鈦 (Anatase titanium dioxide, A-TiO2) 於奈米碳管束陣列上 (Carbon nanotube bundle arrays, CNTBAs)。並藉由電漿處理 (Plasma treatment) 將氮氣摻至銳鈦礦二氧化鈦。之後觀察晶體表面及結構特性，並探討在場發射之應用。
使用場發射電子顯微鏡 (Field-emission scanning electron microscopy, FESEM)、穿透掃描式電子顯微鏡 (Transmission electron microscopy, TEM)、拉曼光譜儀 (Raman spectroscopy) 與X 射線光電子能譜儀 (X-ray photoelectron spectroscopy, XPS) 分析奈米複合材料之表面形貌、晶體大小、晶體結構及晶體化學鍵結與組成。從場發射電子顯微鏡可得知奈米微粒狀的銳鈦礦二氧化鈦均勻大小的附著在奈米碳管壁上；拉曼光譜儀鑑定銳鈦礦二氧化鈦結構成長於奈米碳管結構上並發現新的振動模式D^'-band出現；X 射線光電子能譜儀觀察N 1s、Ti 2p及O 1s元素，得知經過氮氣摻雜後，證實有O-Ti-N鍵結形成；藉由穿透掃描式電子顯微鏡 (Transmission electron microscopy, TEM) 觀察到銳鈦礦二氧化鈦無規則性方向沉積於奈米碳管上。
在場發射實驗中，銳鈦礦二氧化鈦/奈米碳管與摻氮於銳鈦礦二氧化鈦/奈米碳管奈米複合材料在10 A/cm2 分別有1.8 V/m及1.0 V/m的起始電場與在1 mA/cm2 有3.6 V/m及1.9 V/m的臨界電場。而場發射增強因子分別為2700與3000。結果顯示摻氮後能降低銳鈦礦二氧化鈦/奈米碳管束陣列的起始電場及臨界電場，並且擁有較佳穩定性。因此奈米複合結構在場發射研究中是有價值的。

Anatase titanium dioxide (A-TiO2) were grown on top of carbon nanotube (CNT) bundle arrays by metal organic chemical vapor deposition (MOCVD) using titanium-tetraisopropoxide (TTIP, Ti[OCH(CH3)2]4) as the source reagents. The N-doped A-TiO2/CNTs nanocomposite was then fabricated with nitrogen plasma treatment.
The surface morphology, structural and spectroscopic properties of the A-TiO2/CNTs and N-doped A-TiO2/CNTs nanocomposites were characterized using Field-emission scanning electron microscopy (FESEM), Raman spectroscopy, Transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The FESEM image showed a dense coalescence of A-TiO2 with uniform size distribution on the nanotube walls. Raman spectra revealed that nanostructural A-TiO2 had been deposited on the CNT nanocrystals and a new vibration mode of D^'-band at higher wavenumber side was also found. The XPS spectra in the region of N 1s, Ti 2p and O 1s provided a conclusive evidence of the formation of O-Ti-N bond during nitrogen treatment process. The TEM image of A-TiO2 deposited CNT showed uniform distribution, and random directions of A-TiO2 had been grown on the surface of the CNT.
The current density versus electric field measurements yielded turn-on field of 1.8 V/m and 1.0 V/m at a current density of 10 A/cm2, threshold field of 3.6 V/m and 1.9 V/m at a current density of 1 mA/cm2, and field enhancement factor of 2700 and 3000 for the A-TiO2/CNTs and N-doped A-TiO2/CNTs nanocomposites, respectively. Long term stability studies were also carried out. The results indicated that nitrogen doping decreased the turn-on field and threshold field of A-TiO2/CNTs, providing stable field emission applications. The probable mechanisms of field emission enhancement for N-doped A-TiO2/CNTs composite were proposed and discussed.

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