本論文研究係藉由水熱成長(hydrothermal growth, HTG)法與各製程參數(溶液濃度、溫度、反應時間、擾動及蝕刻速度)之調變以進行側向一維氧化鋅(1D-ZnO)奈米結構(奈米柱、奈米尖端及奈米管)之塑型，並將其分別應用於側向短間距二極場發射器(field emitter diode, FE-diode)及場發射氣體感測器之製備與電特性量測分析，主要研究過程可概分為下列二個部份進行：

第一部份為1D-ZnO奈米尖端之塑型研究及具側向短間距(tip-to-tip) FE-diode元件之製備，首先我們利用兩階段HTG方式以進行具側向1D-ZnO奈米尖端之塑型研究，第一階段HTG過程係將鍍有120 nm膜厚之鋁氧化鋅(AZO)晶種層及80 nm膜厚的覆蓋白金(platinum, Pt)電極的試片置入Zn(NO3)2．4H2O及C6H12N4的高濃度混合溶液中，在未擾動溶液並於75°C反應溫度下進行1.5 小時之HTG反應；由SEM影像分析顯示，經第一階段HTG過程後，沿著AZO側邊成長出1D-ZnO奈米柱，其長度及寬度分別約為2~3m及200 nm，且每根奈米柱的頂端皆為平坦六角型表面形狀。接著，將試片置入另一個較低混合溶液濃度Zn(NO3)2．4H2O及C6H12N4、較高反應溫度(95°C)、合成反應時間為2小時及調變溶液擾動速度(300、600、900及1150 rpm)以進行第二階段HTG反應；實驗結果顯示，原先經第一階段HTG過程所成長ZnO奈米柱頂端的六角型平坦表面或頂端邊緣會隨著第二階段HTG過程的擾動速度差異而呈現出多根細維針狀物或單根尖端奈米結構。由此得知，擾動速度之參數調變會影響到後續ZnO奈米尖端之成長形狀及成長位置，研究過程中，我們亦針對1D-ZnO奈米尖端塑型之成長機制進行深入探討。最後，我們依據上述兩階段HTG過程所成長1D-ZnO奈米結構的外觀尺寸進行光罩圖案設計，製備具1D-ZnO奈米尖端之側向短間距(二側尖端間距約為1.2 um) FE-diode元件結構，並在環境壓力為5x10-6 Torr及外加電壓範圍為0~10 V條件下，進行場發射電性量測分析與討論；電性量測結果顯示，於300、600、900及1150 rpm之擾動速度所製備二極元件之起始電壓(Von) 分別為3.12、1.75、1.96與2.38 V (@ 10 uA)，且電場增強因子(field enhancement factor,B)計算值分別為42946、85490、72041與68775 um-1。即於第二階段HTG過程中，擾動速度為600 rpm 時所製備出沿1D-ZnO奈米柱頂端六角平面所成長單根奈米尖端結構之側向短間距元件擁有極低起始電壓(Von)及較高電場增強因子之優越FE電特性，此可歸究於該1D-ZnO奈米尖端結構具有較大高寬比(high aspect ratio)與降低屏蔽效應(screen effect)。

從上述研究成果得知， 1D-ZnO奈米外觀之塑型，確實有效降低二極元件之操作電壓與較大發射電流，但若能利用側向短間距元件可縮短控制陰極端至陽極端距離的優勢，即可進一步減輕或解除其對環境真空度之依賴，因此在第二部分研究過程中，我們使用兩階段HTG方式，製備具側向1D-ZnO奈米管之塑型與能在常壓(760 Torr)下，操作及量測FE-diode氣體感測器之元件。第一階段HTG過程所使用的製程參數皆與第一部分相同，主要差異在於第二階段之製程參數調變，此處我們是將經第一階段HTG過程後之試片置入氫氧化鉀(KOH)溶液(0.125M)、反應溫度(95°C)並調高反應時間(15 min)，以進行第二階段選擇性蝕刻；由SEM影像分析顯示，於第二階段選擇性蝕刻會導致ZnO奈米柱頂端六角平面沿[000-1]被蝕刻成奈米管，其直徑、管壁、長度分別 200~400 nm, 10~50 nm和2~3 μm。接著，我們將此具良好高寬比與高表面積比(surface-to-volume ratio, SVR)之1D-ZnO奈米管技術與1D-ZnO奈米柱，皆應用於具側向短間距(二側尖端間距約為2.5 um) FE-diode元件結構之製備，並於常壓(7.6×102 Torr)環境下分別針對1000 ppm氫氣(H2)混空氣與空氣(Air)及外加電壓範圍為0~6V條件下進行場發射電性量測比較分析；研究結果顯示，此具側向奈米管與奈米柱之FE-diode元件於1000 ppm氫氣(H2)混空氣與空氣(Air)二種不同待測氣體氛圍下展現出迥異的FE電特性，其呈現之起始電壓分別為1.6、2.4、4.1和5V (@I=10uA)，場發射電流為0.20、0.12、0.03和0.02mA，場增強因子(B)為8145、6123、5214及4542 um-1 (@V=6V)，利用暫態分析I-T圖之靈敏度分析顯示，奈米管之敏靈度高於奈米柱16%。
本研究主要係藉由兩階段方式及製程參數之調變以製備出不同外觀形狀(奈米柱、奈米尖端與奈米管)之1D-ZnO奈米結構並分別應用於二極場發射器及場發射氣體感測器；所製備之側向1D-ZnO奈米結構(尖端、管子)具較高長徑比與較大體表面積(surface-to-volume ratio, SVR)，其分別於場發射及氣體感測量測上展現出優越之電特性與靈敏度(sensitivity)，預期本所製備具側向短間距二極元件於未來微電子元件上極具潛力。

In this thesis, the synthesis of one-dimensional (1D) lateral-type ZnO-nanostructures (ZnO-NSs) using hydro-thermal growth (HTG) method and its applications in field emission (FE) diodes and FE gas sensors were investigated.

The present thesis comprises two major parts. The first part focuses on the tip shaping for the laterally-aligned ZnO-NSs and its application in the fabrication of FE diodes with a short tip-to-tip configuration. A two-step HTG method is proposed to synthesize ZnO-NSs and then sharpen the tip portion of the ZnO-NSs. Using a sputtering-deposited 120-nm-thick AZO film as as a seed layer for the lateral growth of ZnO-NSs and a 80-nm-thick Pt layer as a blocking layer on SiO2/Si substrate, the samples were immersed in a high concentration still solution of Zn(NO3)2×4H2O and C6H12N4 at 75°C for 1.5 hr during the first step HTG process. ZnO nanorods with 2-3 um in length and 200 nm in diameter were obtained. After that, the samples were subjected to the second HTG process in a low concentration stirred solution of Zn(NO3)2×4H2O and C6H12N4 at 90°C for 2 hr under a controlled stirring speed (0~1150 rpm). Circulation of the mixed HTG solution renders the ZnO molecular finding nucleation sites with different size, as a result, the growth of multiple-tiny-needle or single needle on the top flat of the ZnO nanorods would occur.

FE diodes employed tip-engineered ZnO-NSs emitters with a short tip-to-tip space (1.2 mm) were fabricated. For the diodes prepared with a stirring speed of 300, 600, 900 and 1150 rpm during the second step HTG process, typical turn-on voltage (Von) of 3.12, 1.75, 1.96, and 2.38V (@I=10uA) and field enhancement factor (b) of 42946, 85490, 72041, and 68775 µm-1 , respectively, were obtained under an ambient pressure of 5X10-6 Torr.

The second part of this thesis focuses on the application of ZnO nanotubes (NTs) prepared by an HTG/etching process in field emission gas sensors. The same first step of the HTG process mentioned previously was employed to synthesize ZnO nanorods (NRs). To realize NTs, the samples were experienced an etching process through immersing in a mixed solution of 0.125M KOH at 95°C for 15 min. It is found that laterally-oriented ZnO NTs with a typical diameter, tube wall thickness, and length of 200~400 nm, 10~50 nm and 2~3 μm, respectively were obtained. In a 1000-ppm H2 ambient, the prepared FE diodes show typical Von of 1.6, 2.4, 4.1 and 5V (@I=10mA), emission current (I) of 0.20, 0.12, 0.03 and 0.02mA (@V=6V) as well as b of 8145, 6123, 5214 and 4542 um-1, respectively. Note that the measured sensitivity (Ihydrogen/Iair) of the prepared FE diodes with ZnO-NTs is around 66% and 50%, respectively.

The laterally-oriented ZnO-NSs and ZnO-NTs prepared by the proposed two-step HTG process or HTG/etching process are with the merits of high aspect-ratio and surface-to-volume ratio (SVR), which are expected to be very promising candidates for vacuum electronics in the near future.

參 考 文 獻
[1] S. Shao, P. Jia, S. Liu, and W. Bai, “Stable field emission from rose-like zinc oxide nanostructures synthesized through a hydrothermal route”, Materials Letters, Vol. 62, p.1200, 2008
[2] H Y Yang, S P Lau, S. F. Yu, L. Huang, M. Tanemura, J. Tanaka, T. Okita, and H. H. Hng, “Field emission from zinc oxide nanoneedles on plastic substrates”, Nanotechnology, Vol. 16, p. 1300, 2005
[3] C. X. Xu and X. W. Sun J, “Strategies to Improve Field Emission Performance of Nanostructural ZnO”, Electron. Mater., Vol. 36, p. 543, 2007
[4] K. C. Chin, C. K. Poh, G. L. Chong, J. Y. Lin, C. H. Sow, and A. T. S. Wee, “Large area, rapid growth of two-dimensional ZnO nanosheets and their field emission performances”, Appl. Phys. A, Vol. 90, p. 623, 2008
[5] J. Chen, W. Lei, W. Chai, Z. Zhang, C. Li, and X. Zhang, “High field emission enhancement of ZnO-nanorods via hydrothermal synthesis”, Solid-State Electron., Vol. 52, p. 294, 2008
[6] K. Hou, and X. W. Sun, “Influence of synthesis temperature on ZnO nanostructure morphologies and field emission properties”, Physica E, Vol. 41, p. 470, 2009
[7] Y. Zhang, D. Lan, Y. Wang, and F. Wang, Chem. China, Vol. 3, p. 229, 2008
[8] J. Chen, W. Lei, W. Chai, Z. Zhang, C. Li, and X. Zhang, “High field emission enhancement of ZnO-nanorods via hydrothermal synthesis”, Solid-State Electron., Vol. 52, p. 294, 2008
[9] C. Y. Lee, T. Y. Tseng, S. Y. Li, and P. Lin, “Electrical characterizations of a controllable field emission triode based on low temperature synthesized ZnO nanowires”, Nanotechnology, Vol. 17, p. 83, 2006
[10] Veljko Milanovic´, Lance Doherty, Dana A. Teasdale, Siavash Parsa, and Kristofer S. J. Pister, “Micromachining Technology for Lateral Field Emission Devices,” IEEE Transactions on Electron Devices, Vol. 48, No. 1, 2001
[11] S. M. Sze, “Semiconductor Devices,” 2nd edition, John Wiley & Sons, Ch. 6, pp. 188.
[12] Jamil Elias, and Ramon Tena-Zaera, “Conversion of ZnO Nanowires into Nanotubes with Tailored Dimensions”, Chem. Mater., Vol. 20, p. 6633, 2008
[13] K. J. Kima, and Y. R. Park, “Large and abrupt optical band gap variation in In-doped ZnO,” Appl. Phys. Lett., Vol. 78, no. 4, p. 475, 2000
[14] Y. Y. Xi, Y. F. Hsu, A. B. Djurisic, A. M. C. Ng, W. K. Chen, H. L. Tam, and K. W. Cheah, “NiO/ZnO light emitting diodes by solution-based growth,” Appl. Phys. Lett., Vol. 92, no. 113505, 2008
[15] Z. K. Tang, G. K. L. Wong, and P. Yu, “Room-temperature ultraviolet laser emission from self-assembled ZnO microcristallite films,” Appl. Phys. Lett., Vol. 72, no. 25, 1998
[16] Hiromichi Ohta, Masahiro Orita, and Masahiro Hirano, “Fabrication and characterization of ultraviolet-emitting diodes composed of transparent p-n heterojunction, p-SrCu2O2 and n-ZnO,” Journal of Applied Physics, Vol. 89, no. 10, 2001
[17] Y. W. Zhu, H. Z. Zhang, X. C. Sun, S. Q. Feng, J. Xu, Q. Zhao, B. Xiang, R. M. Wang, and D. P. Yu “Efficient field emission from ZnO nanoneedle arrays,” Appl. Phys. Lett., Vol. 83, no. 1, 2003
[18] Q. H. Li, Y. X. Liang, Q. Wan, and T. H. Wang, “Oxygen sensing characteristics of individual ZnO nanowire transistors,” Appl. Phys. Lett., Vol. 85, no. 26, 2004
[19] R. S. Wagner, and W. C. Ellis, “Vapor-liquid-solid mechanism of single crystal growth,” Appl. Phys. Lett., Vol. 5, no. 5, p. 89, 1964
[20] R. S. Wagner, and W. C. Ellis, “Vapor-liquid-solid mechanism of single crystal growth,” Appl. Phys. Lett., Vol. 5, no. 5, p. 89, 1964
[21] Y. Wu, and P. Yang, “Direct observation of vapor-liquid-solid nanowire growth,” J. Am. Chem. Soc., Vol. 123, p. 3165, 2001
[22] E. W. Wong, P. E. Sheehan, and C. M. Lieber, “Nanobeam Mechanics: Elasticity, Strength, and Toughness of Nanorods and Nanotubes,” Science, Vol. 277, p. 1971, 1997
[23] W. I. Park, D. H. Kim, S. W. Jung, and G. C. Yi, “Metalorganic vapor-phase epitaxial growth of vertically well-aligned ZnO nanorods,” Appl. Phys. Lett., Vol. 80, p. 4232, 2002
[24] B. Meyer and Dominik Marx, “Density-functional study of the structure and stability of ZnO surfaces”, Am. Phy. Soc., Vol. 67, 035403, 2003
[25] L. Vayssieres, “growth of arrayed nanorods and nanowires of ZnO form aqueous solution,” Adv. Mater., Vol. 15, no. 5, p.464, 2003
[26] Y. Y. Xi, Y. F. Hsu, A.B. Djurisic, A. M. C. Ng, W. K. Chan, H. L. Tam, and K. W. Cheah, “NiO/ZnO light emitting diodes by solution based growth,” Appl. Phsy. Lett., Vol. 92, p. 113505, 2008
[27] M. K. Lee, C. L. Ho, and C. H. Fan, “Enhancement of light extraction efficiency of gallium nitride flip-chip light-emitting diode with silion oxide hemispherical microlens on its back,” IEEE Photonics technology Letters, Vol. 20, no. 15, p. 1293, 2008
[28] K. Tsukuma, T. Akiyama , and Imai, “Liquid phase deposition film of tin oxide,” J. Non-Cryst. Solid, Vol. 210, no. 48, p. 48, 1997
[29] L. Spanhel, and M. A. Anderson, “Semiconductor clusters in the sol-gel process: quantized aggregation, gelation, and crystal growth in concentrated zinc oxide colloids,” J. Am. Chem. Soc., Vol. 113(8), p. 2826, 1991
[30] L. Vayssieres, K. Keis, S. E. Lindquist, and A. Hagfeldt, “Purpose-built anisotropic metal oxide material: 3D highly oriented microrod array of ZnO,” J. Phys. Chem. B., Vol. 105(17), p. 3350, 2001
[31] L. Vayssieres, N. Beermann, S. E. Lindquist, and A. Hagfeldt, “Controlled Aqueous Chemical Growth of Oriented Three-Dimensional Crystalline Nanorod Arrays: Application to Iron(III) Oxides,” Chemistry of Materials., Vol. 13, no. 2, p. 233, 2001
[32] L. Vayssieres, “growth of arrayed nanorods and nanowires of ZnO form aqueous solution,” Adv. Mater., Vol. 15, no. 5, p.464, 2003
[33] L. Vayssieres, K. Keis, S. E. Lindquist, and A. Hagfeldt, “Purpose-built anisotropic metal oxide material: 3D highly oriented microrod array of ZnO,” J. Phys. Chem. B., Vol. 105(17), p. 3350, 2001
[34] Z. R. Tian, J. A. Voigt, J. Liu, B. Mckenzie, and M. J. Mcdermott, “Biomimetic arrays of oriented helical ZnO nanorods and columns,” J. Am. Chem. Soc., Vol. 124(44), p. 12954, 2002
[35] L. E. Greene, M. Law, J. Goldberger, F. Kim, J. C. Johnson, Y. Zhang, R. J. Saykally, and P. Yang, “Low-temperature wafer-scale production of ZnO nanowire arrays,” Angew. Chem., Vol. 115, p. 3139, 2003
[36] Q. Li, V. Kumar, Y. Li, H. Zhang, T. J. Marks, and R. P. H. Chang, “Fabrication of ZnO nanorods and nanotubes in aqueous solution,” Chem. Mater., Vol. 17, p. 1001, 2005
[37] K. Govender, David S. Boyle, P. B. Kenway, and P. O’Brien, “Understanding the factors that govern deposition and morphology of thin film of ZnO from aqueous solution,” J. Mater. Chem., Vol. 14, p. 2575, 2004
[38] R Stratton, “Field Emission from Semiconductors,” Proc. Phys. Soc. B Vol. 68, p.746, 1955
[39] R. H. Fowler and L. W. Nordheim, “Electron emission in intense electric fields”, Proceedings of the Royal Society, Vol. 119, p. 173, 1928
[40] S. H. Jo, D. Z. Wang, J. Y. Huang, W. Z. Li, K. Kempa K and Z. F.Ren, “Field emission of carbon nanotubes grown on carbon cloth”, Appl. Phys. Lett., Vol. 85, no. 810, 2004.
[41] E.I. Givargizov, A.N. Stepanova, E.V. Rakova, A.N. Kiselev and P.S. Plekhanov, “Microstructure and field emission of diamond particles on silicon tips”, Applied Surface Science, Vol. 87, p. 24, 1995.
[42] Q. Zhao, H. Z. Zhang, Y. W. Zhu, S. Q. Feng, X. C. Sun, J. Xu, and D. P.Yu, “Morphological effects on the field emission of ZnO nanorod arrays”, Appl. Phys. Lett., Vol. 86, no. 203115, 2005
[43] T. Utsumi, “Vacuum microelectronics: what's new and exciting”, IEEE Trans. Electron Dev., Vol. 38, p. 2276, 1991
[44] 曾伯霜, “JSM-6700F HR-FESEM Opearation Manual”, Department of Chemical Engineering National Cheng Kung University
[45] Dongwoo Optron Co., Ltd.,”Micro/Macro Photoluminescence Mapping system”, http://optron.en.ec21.com/company_info.jsp
[46] D. C. Kim, B. H. Kong, S. Y. Jeon, J. B. Yoo, and H. K. Cho, “Low-temperature growth and characterization of epitaxial ZnO nanorods by metalorganic chemical vapor deposition”, J. Mater. Res., Vol. 22, no. 7, 2007
[47] X. Fang, Y. Bando, U. K. Gautam, C. Ye and D. Golberg, “Inorganic semiconductor nanostructures and their field-emission applications”, J. Mater. Chem., Vol. 18, no. 509, 2008
[48] B. Meyer and Dominik Marx, “Density-functional study of the structure and stability of ZnO surfaces”, Am. Phy. Soc., Vol. 67, 035403, 2003
[49] A. Wander and N. M. Harrison, “The stability of polar oxide surfaces: The interaction of H2O with Zn (0001) and ZnO(000-1) ”, J. of chem. Phys., Vol. 115, no. 5, 2001
[50] J. Zhang, L. Sun, J. Yin, H. Su, C. Liao, and C. Yan, “Control of ZnO Morphology via a Simple Solution Route ”, Chem. Mater., Vol. 14, no. 4172, 2002
[51] S. Cho, S. H. Jung, and K. H. Lee, “Morphology-Controlled Growth of ZnO Nanostructures Using Microwave Irradiation: from Basic to Complex Structures”, J. Phys. Chem. C., Vol.112, no.12769, 2008
[52] X. L. Hu, Y. J. Zhu, and S. W. Wang, “Sonochemical and microwave-assisted synthesis of linked single-crystalline ZnO rods”, Mat. Chem. and Phys., Vol. 88, no. 421, 2004
[53] J. B. Cuia, C. P. Daghlian, U. J. Gibson, R. Püsche, P. Geithner, and L. Ley, “Low-temperature growth and field emission of ZnO nanowire arrays”, J. of Appl. Phys., Vol. 97, no. 044315, 2005
[54] Z. L. Wang, “Zinc oxide nanostructures: growth, properties and applications”, J. Phys. Condens. Matter, Vol. 16, no. 829, 2004
[55] X. Y. Kong and Z. L. Wang, “Polar-surface dominated ZnO nanobelts and the electrostatic energy induced nanohelixes, nanosprings, and nanospirals”, Appl. Phys. Lett., Vol. 84, no. 6, 2004
[56] Z. L. Wang, X. Y. Kong and J. M. Zuo, “Induced Growth of Asymmetric Nanocantilever Arrays on Polar Surfaces”, Phys Rev Lett., Vol. 91, no. 18, 2003
[57] L. Vayssieres, “Growth of arrayed nanorods and nanowires of ZnO from aqueous solutions”, Adv. Mater., Vol. 15, no. 5, 2003
[58] T. J. Hsueh, S. J. Chang, Y. R. Lin, S. Y. Tsai, I C. Chen, and C. L. Hsu, “A Novel Method for the Formation of Ladder-like ZnO Nanowires”, Crystal Growth & Design, Vol. 6, no. 6, 2006
[59] M. C. Jeong, S. W. Lee, J. M. Seo and J. M. Myoung, “The effect of stacking fault formation on optical properties in vertically aligned ZnO nanowires”, Nanotechnology, Vol. 18, no. 305701, 2007
[60] Y. D., and Z. L. Wang, “Structures of planar defects in ZnO nanobelts and nanowires”, Micron, Vol. 40, no. 335, 2009
[61] S. S. Warule, N. S. Chaudhari, B. B. Kale and M. A. More, “Novel sonochemical assisted hydrothermal approach towards the controllable synthesis of ZnO nanorods, nanocups and nanoneedles and their photocatalytic study”, CrystEngComm, Vol. 11, no. 2776, 2009
[62] D. Wang, C. Song, Z. Hu, W. Chen, and X. Fu, “Growth of ZnO prisms on self-source substrate”, Materials Letters, Vol. 61, no. 205, 2007
[63] Y. Sun, N. G. Ndifor-Angwafor, D. J. Riley, and M. N. R. Ashfold, “Synthesis and photoluminescence of ultra-thin ZnO anowire/nanotube arrays formed by hydrothermal growth”, Chem. Phys. Lett., Vol. 431, no. 352, 2006
[64] M. N.R. Ashfold, R. P. Doherty, N. George Ndifor-Angwafor, D. Jason Riley , and Ye Sun, “The kinetics of the hydrothermal growth of ZnO nanostructures”, Thin Solid Films, Vol. 515, no. 8679, 2007
[65] C. Li, G. Fang, F. Su, G. Li, X. Wu and X. Zhao, “Synthesis and photoluminescence properties of vertically aligned ZnO nanorod–nanowall junction arrays on a ZnO-coated silicon substrate”, Nanotechnology, Vol. 17, no. 3740, 2006
[66] Y.H. Tong, Y.C. Liu, S.X. Lu, L. Dong, S.J. Chen, and Z.Y. Xiao, “The Optical Properties of ZnO Nanoparticles Capped with Polyvinyl Butyral”, Journal of Sol-Gel Science and Technology, Vol. 30, no. 157, 2004
[67] S. Y. Bae, H. W. Seo, and J. Park, “Vertically Aligned Sulfur-Doped ZnO Nanowires Synthesized via Chemical Vapor Deposition”, J. Phys. Chem. B, Vol.108, no. 5206, 2004
[68] U. Pal, and P. Santiago, “Controlling the Morphology of ZnO Nanostructures in a Low-Temperature Hydrothermal Process”, J. Phys. Chem. B, Vol. 109, no. 15317, 2005
[69] H. M. Zhong and W. Lu, “Deep-level emissions influenced by O and Zn implantations in ZnO”, Appl. Phys. Lett., Vol.87, no. 211912, 2005
[70] Y. Sun, N. G. Ndifor-Angwafor, D. J. Riley, and M. N.R. Ashfold, “Synthesis and photoluminescence of ultra-thin ZnO nanowire/nanotube arrays formed by hydrothermal growth”, Chem. Phys. Lett., Vol. 431, no. 352, 2006
[71] C Li, and D L Kwong, “Enhanced field emission from injector-like ZnO nanostructures with minimized screening effect”, Nanotechnology, Vol. 18, no. 135604, 2007
[72] S. H. Jo, J. Y. Lao, and Z. F. Ren, “Field-emission studies on thin films of zinc oxide nanowires”, Appl. Phys. Lett., Vol. 83, no.23
[73] X. Wang, J. Zhou, C. Lao, J. Song, N. Xu, and Z. L. Wang, “In Situ Field Emission of Density-Controlled ZnO Nanowire Arrays”, Adv. Mater., Vol. 19, no. 1627, 2007
[74] Seongjin Kim, Byeong Kwon Ju, and Yun Hi Lee, “Emission characteristic of diamond-tip field emitter arrays fabricated by transfer mold technique”, J. Vac. Sci. Technol. B, Vol. 15, no. 2, 1997
[75] W. P. Kang, J. L. Davidson, M. Howell, B. Bhuva, D. L. Kinser, and D. V. Kerns, “Micropatterned polycrystalline diamond field emitter vacuum diode arrays”, J. Vac. Sci. Technol. B, Vol. 14, no. 3, 1996
[76] S. J. Chang, T. J. Hsueh, C. L. Hsu,Y. R. Lin, I C. Chen and B. R. Huang, “A ZnO nanowire vacuum pressure sensor”, Nanotechnology, Vol. 19, no. 095505, 2008
[77] W. Y. Lee, H. Lin, L. Gu, K. C. Leou, and C. H. Tsai, “CVD catalytic growth of single-walled carbon nanotubes with a selective diameter distribution”, Diamond & Related Materials, Vol. 17, no. 66, 2008
[78] W.Y. Lee, C.H. Weng, Z.Y. Juang, J.F. Lai, K.C. Leou, and C.H. Tsai, “Lateral growth of single-walled carbon nanotubes across electrodes and the electrical property characterization”, Diamond & Related Materials, Vol. 14, no. 1825, 2005
[79] P. Feng, Q. Wan, and T. H. Wang, “Contact-controlled sensing properties of flowerlike ZnO nanostructures”, Appl. Phys. Lett., Vol. 87, no. 213111, 2005
[80] Q. H. Li, Y. X. Liang, Q. Wan, and T. H. Wang, “Oxygen sensing characteristics of individual ZnO nanowire transistors”, Appl. Phys. Lett., Vol. 85, no. 26, 2004
[81] Z. Fan, D. Wang, P. C. Chang, W. Y. Tseng, and J. G. Lu, “ZnO nanowire field-effect transistor and oxygen sensing property”, Appl. Phys. Lett., Vol. 85, no. 24, 2004
[82] G. W. She, X. H. Zhang, and C. H. Liu, “Controlled synthesis of oriented single-crystal ZnO nanotube arrays on transparent conductive substrates”, Appl. Phys. Lett., Vol. 92, no. 053111, 2008
[83] J. Elias, R. T. Zaera, and G. Y. Wang, “Conversion of ZnO Nanowires into Nanotubes with Tailored Dimensions”, Chem. Mater., Vol. 20, no. 6633, 2008
[84] G. She, “Electrochemical/chemical synthesis of highly-oriented single-crystal ZnO nanotube arrays on transparent conductive substrates”, Electrochemistry Communications, Vol. 9, no. 2784, 2007
[85] B. I. Seo, and U. A Shaislamov, “ZnO nanotubes by template wetting process”, Physica E, Vol. 37, no. 241, 2007
[86] C. Noguera, “Polar oxide surfaces”, J. Phys. Condens. Matt., Vol. 12, no. R367, 2000
[87] J. Yoshihara, J. M. Campbell, and C. T. Campbell, “Cu films on a Zn-terminated ZnO(0001) surface: structure and electronic properties”, Surface Science, Vol. 406, no. 235, 1998
[88] C. S. Lao, P. X. Gao, R. S. Yang, Y. Zhang, Y. Dai, and Z. L. Wang, “Formation of double-side teethed nanocombs of ZnO and self-catalysis of Zn-terminated polar surface”, Chemical Physics Letters, Vol. 417, no. 358 ,2006
[89] C.J. Youn, T.S. Jeong, M.S. Han, and J.H. Kim, “Optical properties of Zn-terminated ZnO bulk”, Journal of Crystal Growth, Vol. 261, no. 526, 2004
[90] G. Amin, I. Hussain, S. Zaman, N. Bano, O. Nur, and M. Willander, “Current-transport studies and trap extraction of hydrothermally grown ZnO nanotubes using gold Schottky diode”, Phys. Status Solidi A, Vol. 207, No. 3, 2010
[91] C. wang, Ke yu, and Lijun li, “Synthesis and field emission of two kinds of ZnO nanotubes: taper-like and flat-roofed tubes”, Appl. Phys. A, Vol. 90, no. 739, 2008
[92] C. Li, G. Fang, F. Su, G. Li, X. Wu, and X. Zhao, “Synthesis and photoluminescence properties of vertically aligned ZnO nanorod–nanowall junction arrays on a ZnO-coated silicon substrate”, Nanotechnology, Vol. 17, no. 3740, 2006
[93] Y. H. Tong, Y. C. Liu, S. X. Lu and L. Dong, “The Optical Properties of ZnO Nanoparticles Capped with Polyvinyl Butyral”, Journal of Sol-Gel Science and Technology, Vol. 30, no. 157, 2004
[94] S. Y. Bae, H. W. Seo, and J. Park, “Vertically Aligned Sulfur-Doped ZnO Nanowires Synthesized via Chemical Vapor Deposition”, J. Phys. Chem. B, Vol. 108, no. 5206, 2004
[95] U. Pal, and P. Santiago, “Controlling the Morphology of ZnO Nanostructures in a Low-Temperature Hydrothermal Process”, J. Phys. Chem. B, Vol. 109, no. 15317, 2005
[96] Q. X. Zhao,a P. Klason, and M. Willander, “Deep-level emissions influenced by O and Zn implantations in ZnO”, Appl. Phys. Lett., Vol. 87, no. 211912, 2005
[97] Ye Sun, N. George Ndifor-Angwafor, D. Jason Riley, and Michael N.R. Ashfold, “Synthesis and photoluminescence of ultra-thin ZnO nanowire/nanotube arrays formed by hydrothermal growth”, Chemical Physics Letters, Vol. 431, no. 352, 2006
[98] Y. K. Tseng, C. J. Huang, and H. M. Cheng, “Characterization and Field-Emission Properties of Needle-like Zinc Oxide Nanowires Grown Vertically on Conductive Zinc Oxide Films”, Adv. Funct. Mater., Vol. 13, no. 10, 2003
[99] A. A. Talin, and K. A. Dean, “Field emission disolays: a critical review”, Solid-State Electronics, Vol. 45, no. 963, 2001
[100] K. Subramanian, W. P. Kang, J. L. Davidson, W. H. Hofmeister, B. K. Choi, and M. Howell, “Nanodiamond planar lateral field emission diode”, Diamond & Related Materials, Vol. 14, no. 2099, 2005
[101] Patryk Halek, Grzegorz Halek. and Helena Teterycz, “Influence of humidity on parameters of gold doped tungsten trioxide”, IEEE, Vol. 28, no. 23, 2010
[102] T Yu, FC Cheong, X J Xu, C T Lim, V B C Tan, J T L Thong, and C H Sow, “Large-scale synthesis and field emission properties of vertically oriented CuO nanowire films”, Nanotechnology, Vol. 16, no. 88, 2005
[103] Shih-Chen Shi and Chia-Fu Chen, “Field emission from quasi-aligned aluminum nitride nanotips”, Appl. Phys. Lett., Vol. 87, no. 073109, 2005