奈米碳管之功能化:表面修飾與摻雜效應

Functionalized Carbon Nanotubes:Surface Decoration and Doping Effect

郭信甫(Hsin-Fu Kuo)

指導教授 ： 徐文光

國立清華大學/工學院/材料科學工程學系/博士(2007年)

https://doi.org/10.6843/NTHU.2007.00248

摘要

摘要

本研究主要討論表面修飾（非共價性交互作用）與摻雜對奈米碳管的物理以及化學性質之影響。例如，藉由表面反應造成表面張力改變，氣體偵測的靈敏度增加以及碳管純化的效果。眾所皆知，在傳統矽晶圓半導體元件中，摻雜是調變電性最有效的方法，對於奈米碳管的電性改質亦是如此，然而較少有人討論形變對於元件電性的影響。因此在本論文中，我們針對「彎曲效應」對於不同碳管（實驗中採用了摻雜硼的多壁碳管與純單壁碳管）的電性影響做進一步探討。

第一章
首先簡介藉由不同分子（例如：高分子、介面活性劑等）對碳管表面進行改質的基本觀念。藉利用紅外線光譜的變化來辨別、鑑定分別來自管內與管外兩種不同吸附機制所產生的效應，並深入討論之。

第二章
再進入主題前，本章節先介紹實驗所使用的儀器、步驟、方法與本論文所利用的實驗概念。

第三章
此章節主要探討如何使用氨去除碳管表面雜質（例如：非晶形碳、催化劑），實驗中發現藉由浸泡氨水可使碳管表面吸附氨分子。再透過閃光燈（提供紫外光源）的照射（產生鳴爆），可將碳管表面的非晶形碳與金屬催化劑有效去除而得到純碳管。實驗結果發現經由上述步驟處理過的碳管對於氣體感測能力有大幅度的提昇（約增加3.8倍）。

第四章
透過觀測去離子水液滴形狀的改變與遷移，並進一步利用理論計算得知氨分子對碳管薄膜的表面改質所造成之表面張力變化。藉由對照組實驗提出合理的機制並預測液滴在外加的電磁場中的行為。

第五章
對照純碳管與摻硼碳管在受力彎曲時的電性改變行為，進一步探討電子穿隧。實驗數據配合理論計算建立電子於形變碳管中的穿隧行為乃一量子化的結果。

第六章
總結以上各章節的結果並提供未來可供研究之議題。

關鍵字

奈米碳管 ； 氣體靈敏度 ； 表面張力 ； 彎曲效應

並列摘要

Abstract

The works presented in this thesis discuss the effects of non-covalent interaction with carbon nanotubes and molecules as well as Boron-dopants modify electronic structure of carbon nanotubes. Surface decoration has been proved to be important in changing the physico-chemical properties of nanotubes. For example, surface tension, gas sensing and purification via surface reaction are discussed in this study. Doping is well known effective in changing electrical properties of Si-based devices, and it also works in carbon nanotubes. In this study, we demonstrate how bending effect electrical properties in Boron-doped carbon nanotubes (BCNTs) and single-walled carbon nanotubes (SWCNTs).

Chapter 1 introduces the basic concept of nanotubes surface decoration by different molecules, e.g. polymers, surfactants, and others chemical species. Two attachments will be discussed, inside and outside the tube, along with the influence of infrared spectroscope analyses.

Chapter 2 will discuss the experimental methods, and characterization techniques employed in this study.

Chapter 3 shows the ammonia blast on nanotube surface. This work demonstrates the removal of carbonaceous impurities and catalytic particles from carbon nanotube surfaces by ammonia explosion and data reveals that gas sensitivity of purified nanotubes becomes faster by a factor of 3.8 compared with pristine materials.
Chapter 4 discusses the observations of surface tension change upon NH3 attachment and droplet (deionized water) migration on nanotube surface. Droplet moving rate, surface tensions of pristine and decorated nanotube films are calculated from experiment information. Feasible mechanism is proposed and influence of droplet migration by external magnetic field is also predicted.

Chapter 5 mainly focuses on electron tunneling through boron doped carbon nanotubes. We also show the difference electronic behavior between undoped and B-doped nanotubes. In this chapter, we describe the phenomenon of nanotube deflection driven electron transmission.

Chapter 6 concludes results of our experiments.

並列關鍵字

carbon nanotubes ； gas sensitivity ； surface tension ； bending effect

參考文獻

Chapter 1

[1] R. Saito, G. Dresselhaus, M. S. Dresselhaus, Physical Properties of Carbon Nanotubes, Imperial College Press, London, 1998.

[2] N. Wang, Z. K. Tang, G. D. Li, J. S. Chen, Nature 408, 50 (2000)

[4] S. Iijima, Nature, 354, 56 (1991)

[6] A. Thess, R. Lee, P. Nikolaev, H. Dai, P. Petit, J. Robert, C. Xu, Y. H. Lee, S. G. Kim, A. G. Rinzler, D. T. Colbert, G. E. Scuseria, D. Tomanek, J. E. Fischer, R. E. Smalley, Science 273, 483. (1996)