臺灣博碩士論文加值系統

本論文主要研究奈米碳管之成長機制及其電子場發射性質之應用。使用一個兩階段成長方法首先利用離子束濺鍍沉積法 (ion beam sputtering deposition；IBSD)於矽晶片或康寧玻璃基板上濺鍍一層過渡金屬催化薄膜 (Fe or Ni catalyst thin film)， 做基材的氫電漿前處理而得到奈米尺寸金屬催化微粒，然後使用微波電漿輔助化學氣相沉積法(microwave plasma-enhanced chemical vapor deposition； MPECVD)合成奈米碳管。已經成功利用微波電漿輔助化學氣相沉積法直接於矽晶片或康寧玻璃基板在500 °C的低溫下合成大面積、均勻且高準直性的奈米碳管。研究中發現金屬催化薄膜的厚度為影響奈米碳管低溫製程最重要的因素。奈米碳管的長度、直徑以及準直性可以做系統性的控制藉由改變製程參數，這些參數包括微波功率、壓力、反應溫度、反應時間、氮氣流量以及金屬催化薄膜的厚度等。高解析的電子顯微鏡(HRSEM)以及穿透式電子顯微鏡(HRTEM)被使用來鑑定奈米碳管的表面形貌及結構。拉曼光譜(Raman spectra)則被使用來分析奈米碳管薄膜的鍵結。
在奈米碳管之場發射性質應用方面，在場發射電性量測方面發現在500 °C低溫合成的奈米碳管有相當低的起始電場 (6.2 V/μm)及高的場發射電流密度(0.1 mA/cm2)，然而在1000 °C沉積的奈米碳管有更低的起始電場 (2.8 V/μm)及較高的場發射電流密度(35 mA/cm2)。

This thesis is mainly focused on the synthesis and field emission property applications of carbon nanotubes (CNTs). A two-step process was employed to synthesize CNTs in that ion beam sputtering deposition (IBSD) was used to deposit iron or nickel catalyst thin films on silicon and Corning glass 7059 followed by hydrogen plasma pretreatment to form nano-size Fe or Ni particles and the CNTs growth by microwave plasma-enhanced chemical vapor deposition (MPECVD) at the second step.
Well-aligned, uniform carbon nanotubes (CNTs) have been obtained in large area at low temperature of 500 °C using the present technique. The thickness of the catalyst thin film was found to be the most important factor in the low temperature growth process. Systematic control of the length, diameter, and alignment of the CNTs has been achieved by changing the deposition parameters such as microwave power, pressure, temperature, N2 flow rate and thickness of catalyst film. High resolution SEM and TEM were used to characterize the morphology and structure of the nanotubes. Raman spectroscopy was employed to analyze the bonding state of CNTs.
For the property of the carbon nanotubes, field emission measurement showed a low turn on field (6.2 V/μm) and high emission current density (0.1 mA/cm2) for the films grown at a low temperature of 500 °C. However, a much lower turn on field (2.8 V/μm) and higher emission current density (35 mA/cm2) can be achieved for the films grown at a higher temperature of 1000 °C.

Abstract (Chinese).........................................iii
Abstract (English)..........................................iv
Acknowledgement..............................................v
Table of Contents...........................................vi
List of Tables............................................viii
List of Figures.............................................ix
Chapter 1. Introduction......................................1
1.1 History of carbon nanotubes..............................1
1.2 Structure of carbon nanotubes............................2
1.3 The methods of synthesizing carbon nanotubes.............4
1.3.1 Arc discharge method...................................4
1.3.2 Laser ablation.........................................5
1.3.3 Thermal chemical vapor deposition......................6
1.4 Properties and applications of carbon nanotubes..........7
1.4.1 Field emission display.................................7
1.4.2 Compound material......................................8
1.4.3 The probe of atomic force microscopy...................8
1.4.4 Storage of hydrogen gas................................9
1.5 Alignment of carbon nanotubes...........................10
1.6 Motive of this thesis...................................12
Chapter 2. Experiment and characterization..................13
2.1 Experiment .............................................13
2.1.1 Preparation of substrates.............................13
2.1.2 Flow chart of synthesis and characterization of CNTs…14
2.1.3 Ion beam sputtering deposition (IBSD).................15
2.1.4 Microwave plasma enhanced CVD (MPECVD)................18
2.2 Characterization........................................19
2.2.1 Scanning electron microscopy..........................19
2.2.2 High-resolution transmission electron microscopy......20
2.2.3 Raman spectroscopy....................................20
2.2.4 Field emission measuremen.............................21
Chapter 3. Results and discussion...........................22
3.1 Synthesis...............................................22
3.1.1 Deposition of Fe catalyst layer.......................22
3.1.2 Growth procedure of CNTs..............................23
3.1.3 Fe catalyst thickness dependence......................25
3.1.4 Temperature dependence................................29
3.1.5 Fe catalyst thickness and temperature dependence......32
3.1.6 Temporal evolution of CNTs growth.....................34
3.1.7 N2 flow rate dependence for CNTs growth...............35
3.1.8 HRTEM of the CNTs.....................................38
3.1.9 Analysis of Raman spectra for CNTs films .............41
3.1.10 Growth mechanism of well-aligned CNTs................43
3.1.11 Formation of CNTs films using Ni catalyst layer......45
3.1.12 Field emission measurement...........................49
Chapter 4 Conclusion........................................52
Chapter 5 Future work.......................................53 Reference...................................................54
Introduction of author......................................56

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