臺灣博碩士論文加值系統

本論文利用熱化學氣相沉積法於碳布上合成奈米碳管。為了增強奈米碳管的場電子發射特性，本研究利用硝酸的化學改質處理，移除奈米碳管頂部的金屬觸媒。不同硝酸處理時間的奈米碳管的場發射特性皆被量測。結果顯示，當硝酸處理時間為 15 分鐘時，臨界電場有一最佳值1.9 V/um。當硝酸處理時間大於15 分鐘，由於表面會形成缺陷而影響場發射。此一最佳條件雖降低了奈米碳管的臨界電場，但其穩定性量測卻不佳。為增強穩定性，本研究再進一步在化學改質後的奈米碳管表面，合成氧化鋅奈米結構。實驗結果得知，在合成氧化鋅於15 分鐘硝酸處理的奈米碳管上後，其穩定性獲得改善，並有一最小臨界電場值為 1.5 V/um。

Carbon nanotubes (CNTs) were synthesized on carbon cloth by thermal chemical vapor deposition (TCVD). To enhance the field emission current, catalyst metal at the tip of CNTs was removed by chemical modifications with nitric acid (HNO3). The field emission characteristics of CNTs with various HNO3 immersion time were investigated. As a result, when the HNO3 immersion time was 15 min, the threshold electric field (Eth) has the lowest value of 1.9 V/um. When the immersion time was extended, the Eth increased due to defects at the surface of CNTs. Although the Eth was decreased with the optimal condition of HNO3 treatment, the long-term stability of as treated CNTs was poor. To improve the stability, ZnO nanostructures were synthesized on the surface of the open-end CNTs. Consequently, the long-term stability of the CNTs was improved and an even lower Eth, i.e. 1.5 V/um, was obtained.

Abstract (in Chinese) ------------------------------------------------- I
Abstract (in English) ------------------------------------------------- II
Acknowledgement (in Chinese) ------------------------------------------ III
Contents -------------------------------------------------------------- IV
Figure captions ------------------------------------------------------- VI
Table list ------------------------------------------------------------ X
Chapter 1 Introduction ------------------------------------------------ 1
1.1 Materials of cold cathode emitter for field emission displays ----- 1
1.2 Structure and properties of CNTs ---------------------------------- 3
1.2.1 Categories of CNTs ---------------------------------------------- 4
1.2.2 Properties of CNTs ---------------------------------------------- 6
1.3 Theory of field emission ------------------------------------------ 7
1.3.1 Fowler Nordheim relations ------------------------------------- 7
1.3.2 Factors that affect field emission ---------------------------- 8
1.4 Motivation -------------------------------------------------------- 9
1.4.1 Chemical modification ------------------------------------------- 9
1.4.2 ZnO on open-end CNTs -------------------------------------------- 9
Chapter 2 Experimental methods ---------------------------------------- 11
2.1 Experimental process flow chart ----------------------------------- 11
2.2 Manufacturing procedure ------------------------------------------- 12
2.2.1 Substrate preparation ------------------------------------------- 12
2.2.2 E-beam evaporation ---------------------------------------------- 12
2.2.3 The synthesis of carbon nanotubes ------------------------------- 14
2.2.4 The nitric acid treatment --------------------------------------- 17
2.2.5 The growth of tapered ZnO over open-end CNTs -------------------- 18
2.3 Analysis and characterization ------------------------------------- 20
2.3.1 Scanning electron microscopy ------------------------------------ 20
2.3.2 Transmission electron microscopy ------------------------------- 21
2.3.3 Raman spectroscopy ---------------------------------------------- 21
2.3.4 Fourier transform infrared spectroscopy ------------------------- 22
2.3.5 Field emission measurement -------------------------------------- 23
Chapter 3 Results and discussion -------------------------------------- 26
3.1 HNO3 treated carbon nanotubes ------------------------------------- 26
3.2 ZnO-coated carbon nanotubes --------------------------------------- 26
3.3 The stability and uniformity -------------------------------------- 41
Chapter 4 Conclusions ------------------------------------------------- 44
References ------------------------------------------------------------ 45

[1]S. Itoh, T. Watanabe, K. Ohtsu, M. Taniguchi, S. Uzawa, and N. Nishimura, "Experimental study of field emission properties of the Spindt-type field emitter," in 7th International Vacuum Microelectronics Conference, Grenoble, France, 1995, pp. 487-490.
[2]K. L. Ng, J. Yuan, J. T. Cheung, and K. W. Cheah, "Electron field emission characteristics of electrochemical etched Si tip array," Solid. State. Commun., vol. 123, pp. 205-207, 2002.
[3]M. W. Geis, J. C. Twichell, and T. M. Lyszczarz, "Diamond emitters fabrication and theory," in The eighth international vacuum microelectronics conference, Portland, Oregon (USA), 1996, pp. 2060-2067.
[4]S. H. Jo, J. Y. Lao, Z. F. Ren, R. A. Farrer, T. Baldacchini, and J. T. Fourkas, "Field-emission studies on thin films of zinc oxide nanowires," Appl. Phys. Lett., vol. 83, pp. 4821-4823, 2003.
[5]D. C. Lim, H. S. Ahn, D. J. Choi, C. H. Wang, and H. Tomokage, "The field emission properties of silicon carbide whiskers grown by CVD," Surf. Coat. Technol., vol. 168, pp. 37-42, 2003.
[6]W. B. Choi, D. S. Chung, J. H. Kang, H. Y. Kim, Y. W. Jin, I. T. Han, Y. H. Lee, J. E. Jung, N. S. Lee, G. S. Park, and J. M. Kim, "Fully sealed, high-brightness carbon-nanotube field-emission display," Appl. Phys. Lett., vol. 75, pp. 3129-3131, 1999.
[7]H. W. Kroto, J. R. Heath, S. C. O'Brien, R. F. Curl, and R. E. Smalley, "C60: Buckminsterfullerene," Nature, vol. 318, pp. 162-163, 1985.
[8]W. Kratschmer, L. D. Lamb, K. Fostiropoulos, and D. R. Huffman, "Solid C60: a new form of carbon," Nature, vol. 347, pp. 354-358, 1990.
[9]J. A. E. Gibson, "Early nanotubes?," Nature, vol. 359, pp. 369-369, 1992.
[10]S. Iijima, "Helical microtubules of graphitic carbon," Nature, vol. 354, pp. 56-58, 1991.
[11]R. H. Fowler and L. Nordheim, "Electron Emission in Intense Electric Fields," Proc. R. Soc. London. A, vol. 119, pp. 173-181, 1928.
[12]F. Arai, P. Liu, L. Dong, T. Fukuda, T. Noguchi, and K. Tatenuma, "Pure metal deposit using multi-walled carbon nanotubes decorated with ruthenium dioxide super-nanoparticles," in 2004 4th IEEE Conference on Nanotechnology, Munich, 2004, pp. 196-198.
[13]S. K. Srivastava, V. D. Vankar, D. V. Sridhar Rao, and V. Kumar, "Enhanced field emission characteristics of nitrogen-doped carbon nanotube films grown by microwave plasma enhanced chemical vapor deposition process," Thin Solid Films, vol. 515, pp. 1851-1856, 2006.
[14]T. W. Weng, Y. H. Lai, and K. Y. Lee, "Area effect of patterned carbon nanotube bundle on field electron emission characteristics," Appl. Surf. Sci., vol. 254, pp. 7755-7758, 2008.
[15]D. Shiffler, O. Zhou, C. Bower, M. LaCour, and K. Golby, "A high-current, large-area, carbon nanotube cathode," IEEE T. Plasma Sci., vol. 32, pp. 2152-2154, 2004.
[16]A. G. Rinzler, J. H. Hafner, P. Nikolaev, P. Nordlander, D. T. Colbert, R. E. Smalley, L. Lou, S. G. Kim, and D. Tomanek, "Unraveling Nanotubes: Field Emission from an Atomic Wire," Science, vol. 269, pp. 1550-1553, September 15 1995.
[17]T. W. E. Hidefumi Hiura, Katsumi Tanigaki,, "Opening and purification of carbon nanotubes in high yields," Adv. Mater., vol. 7, pp. 275-276, 1995.
[18]K. C. Hwang, "Efficient cleavage of carbon graphene layers by oxidants," J. Chem. Soc., Chem. Commun., pp. 173-174, 1995.
[19]R. M. Lago, S. C. Tsang, K. L. Lu, Y. K. Chen, and M. L. H. Green, "Filling carbon nanotubes with small palladium metal crystallites: The effect of surface acid groups," J. Chem. Soc., Chem. Commun., pp. 1355-1356, 1995.
[20]S. C. Tsang, Y. K. Chen, P. J. F. Harris, and M. L. H. Green, "A simple chemical method of opening and filling carbon nanotubes," Nature, vol. 372, pp. 159-162, 1994.
[21]翁诗甫, 傅里叶变换红外光谱仪: 化学工业出版社, 2005.
[22]L. H. Chan, K. H. Hong, D. Q. Xiao, W. J. Hsieh, S. H. Lai, H. C. Shih, T. C. Lin, F. S. Shieu, K. J. Chen, and H. C. Cheng, "Role of extrinsic atoms on the morphology and field emission properties of carbon nanotubes," Appl. Phys. Lett., vol. 82, pp. 4334-4336, 2003.
[23]M. T. Mart′ınez, M. A. Callejas, A. M. Benito, M. Cochet, T. Seeger, A. Anso′n, J. Schreiber, C. Gordon, C. Marhic, O. Chauvet, J. L. G. Fierro, and W. K. Maser, "Sensitivity of single wall carbon nanotubes to oxidative processing: structural modification, intercalation and functionalisation," Carbon, vol. 41, pp. 2247-2256, 2003.
[24]Y.-S. Min, E. J. Bae, J. B. Park, U. J. Kim, W. Park, J. Song, C. S. Hwang, and N. Park, "ZnO nanoparticle growth on single-walled carbon nanotubes by atomic layer deposition and a consequent lifetime elongation of nanotube field emission," Appl. Phys. Lett., vol. 90, pp. 263104-3, 2007.
[25]C. Liu, K. S. Kim, J. Baek, Y. Cho, S. Han, S.-W. Kim, N.-K. Min, Y. Choi, J.-U. Kim, and C. J. Lee, "Improved field emission properties of double-walled carbon nanotubes decorated with Ru nanoparticles," Carbon, vol. 47, pp. 1158-1164, 2009.
[26]H. Zhang, M. Finnegan, and J. F. Banfield, "Preparing Single-Phase Nanocrystalline Anatase from Amorphous Titania with Particle Sizes Tailored by Temperature," Nano Lett., vol. 1, pp. 81-85, 2001.
[27]G. Liu, F. Li, D.-W. Wang, D.-M. Tang, C. Liu, X. Ma, G. Q. Lu, and H.-M. Cheng, "Electron field emission of a nitrogen-doped TiO2 nanotube array," Nanotechnology, p. 025606, 2008.
[28]H. Horiuchi, R. Katoh, K. Hara, M. Yanagida, S. Murata, H. Arakawa, and M. Tachiya, "Electron Injection Efficiency from Excited N3 into Nanocrystalline ZnO Films: Effect of (N3-Zn2+) Aggregate Formation," J. J. Phys. Chem. B, vol. 107, pp. 2570-2574, 2003.
[29]X. Feng, K. Shankar, O. K. Varghese, M. Paulose, T. J. Latempa, and C. A. Grimes, "Vertically Aligned Single Crystal TiO2 Nanowire Arrays Grown Directly on Transparent Conducting Oxide Coated Glass: Synthesis Details and Applications," Nano Lett., vol. 8, pp. 3781-3786, 2008.