奈米碳材料之光電特性分析

Optical and Electrical Characterizations of Carbon Nano-Materials

焦彥棠(Yen-tang Chiao)

指導教授 ： 蔡宗惠

大同大學/電機資訊學院/光電工程研究所/碩士(2010年)

摘要

本論文分成兩個部份，針對兩種碳奈米結構分別做光學和電性的探討。
第一部分是利用磁控濺鍍系統製作垂直之奈米碳片(carbon nano- partition, CNP)。此垂直CNP陣列具有獨特之光學特性，可做抗反射層之用，我們成長CNP於矽及石英兩種不同基板，之後對其進行反射率量測及透射率的測量，發現奈米碳片可在光波長250 ~ 850 nm有效降低其平均反射率至0.2%，其中於波長328 nm更可降至0.13%。
第二部分我們測量經過電弧放電系統快速高溫退火的多壁奈米碳管(multi-walled carbon nanotube, MWCNT)之電性，並與未處理過的MWCNT做比較，可以發現改質後的碳管導電率明顯優於原本的碳管，而且藉由溫度變化對碳管導電率的量測實驗，我們得到一個有趣的結果，經退火處理過的MWCNT導電率會隨環境溫度升高而升高，如同某些特定單壁奈米碳管所具有的半導體特性，這有別於先前某些研究族群認定MWCNT是金屬性導電模式。我們推論快速高溫退火處理有效降低了MWCNT的內部缺陷，使電子在傳輸過程中的散射降低，並導正以MWCNT之最外殼層為傳輸通道，而顯現其半導體特性。

關鍵字

奈米碳片 ； 抗反射 ； 奈米碳管 ； 熱退火 ； 電性

並列摘要

This thesis is mainly focused on carbon nano-materials. Two structures of carbon are discussed which are carbon nano-partitions (CNPs) and multi-walled carbon nanotubes (MWCNTs).
In the first part of this thesis, we fabricated carbon flakes vertically standing on the substrate by radio frequency sputter. Then we measured the reflection and transmission in 250 to 850 nm of the wavelength on such CNPs array. We found that the CNP has good anti-reflection property. The average reflectance is 0.2% from one of our best sample in visible range. The lowest reflectance is 0.13% at 328 nm. This unique nano-material can be acted as a black body which is similar to the optical property with highly absorption of light by the sparse CNT. The detail optical characterization of anti-reflection verse different angles from such nano-material is also discussed.
On the second part of this thesis, we measured the electrical property of the MWCNT. Our experiment show the rapid thermal annealed (RTA) multi-walled CNT can be imported. The post treated CNT exhibited higher conductance. As for control sample, the high density defects limited the carrier mobility which leads to the higher resistance. As experimental sample, the defects are nearly removed, so the carrier can achieve higher mobility. From the measurement of electrical conductance in different temperatures, the annealed CNT exhibited semiconductor characteristic. Higher temperature gives more excited carriers which leads to better conduction. Our results suggested that well-structured MWCNT can acts as a semiconductor which the carrier transport via outer shell of CNT and gives the electrical conductance via the 1D nano-channel.

並列關鍵字

carbon nano-partitions ； anti-reflection ； carbon nanotubes ； thermal annealing ； electrical characterization

參考文獻

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