- 學位論文
利用電漿輔助化學氣相沈積多階段製程合成奈米碳管與增進場發射特性之研究
Enhanced field emission characteristics of carbon nanofibers by multi-stage growth process
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摘要
奈米碳管材料所具有獨特的結構，極佳的機械、熱傳導、化學穩定性與其高深寬比之特性等使其應用潛力極為廣泛，可應用於結構複合材料、儲能材料、奈米導線、奈米探針、場發射元件等。 利用電感式電漿輔助化學氣相沈積( ICP-CVD )方法可以大面積成長以及準直性的奈米碳管，在較低的製程溫度( T < 500 ℃)，適合應用在顯示器元件的玻璃基板上。增加場發射特性的方法有二點：一是減少奈米碳管在場發射過程中的屏蔽效應( screen effect )以降低起始電場( turn-on field )；以及增加場發射電流的均勻度(uniformity)和穩定性(stability)。 本研究利用多階段的電漿處理與奈米碳管成長製程來達到此目標。首先藉由電漿前處理來控制催化劑密度，以進一步控制奈米碳管之密度，以減少屏蔽效應對場發射特性不良的影響。再利用電漿後處理縮小碳管頂端的催化劑。使得奈米碳管呈現尖錐狀，同時增加奈米碳管以及基板表面的接著性。接著第二階段的奈米碳管再成長製程，使奈米碳管利用頂端縮小的催化劑成長直徑較小的奈米碳管，以增加奈米碳管的長徑比。再利用調變後處理以及再成長的參數，使其場發射特性達到最佳化。 在結果部分，本研究成功發展多階段製程系統在玻璃基板上成長奈米碳管；有效的控制奈米碳管密度以及降低起始電場(從22.68 V /um降到7.16 V /um)，達到增進場發射特性的目的。
並列摘要
Direct synthesis of vertically aligned CNFs has been successfully fabricated on display glass substrates at low temperature (< 500 ℃) by inductive couple plasma-enhance chemical vapor deposition (ICP CVD). Such process technique can be easily integrated with micro-fabrication process and can be scaled up for large size substrates. How to decrease the screen effect and turn-on field and increase the uniformity of CNFs is the way to enhance the field emission characteristics. This study used multi-step growth process and plasma treatment to achieve the goal. First, control the density of CNFs by plasma pre-treatment which controlling the size and density of catalytic nanoparticles. Second, diminish the size of catalyst which staying in the tip of CNFs by plasma post-treatment. CNFs exhibit spindt type and increased the adhesion between CNFs and substrate. Then, re-grow small diameter of CNFs on treated catalyst which stay in the tip of CNFs to increase aspect ratio. Optimize the post-treatment and re-growth parameter to enhance the field emission characteristics. This study succeeded to develop multi-step growth process on glass substrate and enhance the field emission characteristics by integrated and optimized to control the size and density of CNFs and decreased turn-on field from 22.68 V / um to 7.16 V / um.
參考文獻
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