在這項研究中，提出了一個自下而上的奈米線元件的製造中使用的新方法。指插式圖案電極是以標準黃光微影製程製作。高溫爐管成長之P-型矽奈米線是使用介電泳技術對齊，使其與電極金屬接觸。之後再以電鍍法鍍上一層鎳來加厚電極，傳統的水溶液電鍍法以在此研究中證明不適合用於奈米/微米尺度電鍍。所以離子液體，氯化膽鹼和尿素的混合物，被選為用於沉積鎳之電鍍液。鎳沉積可改善P-矽奈米線和金屬之間的接觸並產生線性的IV曲線，為了促進非晶界面層上的一致P-矽納米線。元件會以500度C快速熱退火進一步提高並鈍化非晶界面層接觸。最後，在這項研究中此元件的pH感測度也被檢測。實驗結果顯示，在不同pH值之間的靈敏度是以電阻值之變化來表示。由於奈米線有高表面體積比，pH值檢測結果發現幾乎是瞬時的。在奈米線外表使用更具穩定性的絕緣物質可提高此元件的耐用度。

A novel method of using electrodeposition in bottom-up fabrication of nanowire devices is proposed in this study. Inter-digit patterned electrodes were fabricated by standard photolithography. As-grown p-type silicon nanowires were aligned using dielectrophoresis technique followed by electrodeposition of nickel. Traditional aqueous solution was found to be inappropriate for nano/micron scale electrodeposition. Ionic liquid, a mixture of choline chloride and urea, was chosen as the electroplating solution for nickel deposition. The deposition of nickel has shown contact improvement between p-silicon nanowires and metal, leading to near-linear I-V curve, which is facilitated by an amorphous interfacial layer on the aligned p-silicon nanowires. The device is being treated with rapid thermal annealing at 5000C to further improve the contact and to passivate the amorphous interfacial layer. Finally, the capability of pH sensing is being investigated in this study. Experimental results have shown pH level sensitivity among pH buffer solutions by electrical resistance measurement. Due to high surface to volume ratio of the nanowires, the pH level sensing was found almost instantaneous. A possible improvement for stability is also investigated.

[1] M.Schlesinger, Electrochemistry Encyclopedia, http://electrochem.cwru.edu/encycl
[2] H.A. Pohl, Dielectrophoresis the behavior of neutral matter in nonuniform electric fields. Cambridge University Press. Cambridge. 1978.
[3] M.L.Li, S.L.Leung, Y.L. Qu, Z.L. Dong, and W.J. Li. Dielectrophoresis assembly of 2nm gold particles for nano-sensing applications. 5th IEEE International Conference on Nano/Micro Engineered and Molecular Systems in China. 2010.
[4] A. Motayed, M. He, A.V.Davydov, J.Melngailis, and S.N.Mohammad. Realization of reliable GaN nanowire transistors utilizing dielectrophoretic alignment technique. Journal of Applied Physics 100, 114310. 2006.
[5] C. Xu, L.Zhang, H.Zhang, and H.Li. Well-dispersed gold nanowire suspension for assembly application. Applied Surface Science 252, 1182-1186. 2005.
[6] Y.Huang, T.Knowles, and E.Terentjev. Strength of nanotubes, filaments, and nanowires from sonication-induced scission. Advanced Materials 21, 3945-3948. 2009.
[7] M.Beaux, J.Haas, N.Bridges, N.H.Kwon, and D.McIlroy. Reynolds number manipulation of mean nanowire lengths and nanowire suspension quantification. Journal of Applied Physics 110, 024313. 2011.
[8] Andrew P. Abbott, Glen Capper, David L. Davies, Raymond K. Rasheed, and Vasuki Tambyrajah. Novel solvent properties of choline chloride/urea mixtures. ChemComm, 70-71. 2003.
[9] Liana Anicai, Andreea Florea, and Teodor Visan. Studies Regarding the Nickel Electrodeposition from Choline Chloride Based Ionic Liquids. Applications of Ionic Liquids in Science and Technology 261-286.
[10] S.N. Mohammad. Contact mechanism and design principles for (Schottky and Ohmic) metal contacts to semiconductor nanowires. Journal of Applied Physics 108, 034311. 2010.
[11] S.Choi, I.Park, Z.Hao, H.Y.N.Holman, A.P.Pisano. Quantitative studies of long-term stable, top-down fabricated silicon nanowire pH sensors. Applied Physics A. 107, 421-428. 2012.
[12] S. Raychaudhuri, Shadi A. Dayeh, Deli Wang, and Edward T. Yu. Precise Semiconductor Nanowire Placement Through Dielectrophoresis. Nano Letters Vol.9, No.6. 2260-2266. 2009.
[13] Ming Lin Li, Siu Ling Leung, Yan Li Qu, Zai Li Dong, and Wen J. Li. Dielectrophoretic Assembly of 2nm Gold Particles for Nano-sensing Applications. Proceedings of the 2010 5th IEEE International Conference on Nano/Micro Engineered and Molecular Systems. January 20-23, Xiamen, China.
[14] A.W. Maijenburg, M.G. Maas, E.J.B. Rodijk, W.Ahmed, E.S. Kooij, E.T.Carlen, D.H.A. Blank, and J.E. ten Elshof. Dielectrophoretic alignment of metal and metal oxide nanowires and nanotubes: a universal set of parameters for bridging prepatterned microelectrodes.Journal of Colloid and Interface Science 355, 486-493. 2011.
[15] Y.Tsuru, M.Nomura, and F.R.Foulkes. Effects of chloride, bromide and iodide ions on internal stress in films deposited during high speed nickel electroplating from a nickel sulfamate bath. Journal of Applied Electrochemistry 30, 231-238. 2000.
[16] A.Florea, L.Anicai, S.Costovici, F.Golgovici, and T.Visan. Ni and Ni alloy coatings electrodeposited from choline chloride-based ionic liquids-electrochemical synthesis and characterization. Surface and Interface Analysis 42. 1271-1275. 2010
[17] A.P.Abbott, K.El Ttaib, K.S.Ryder, and E.L.Smith. Electrodeposition of nickel using eutectic based ionic liquids. Transactions of the Institute of Metal Finishing. Vol 86. 2008.
[18] I.Park, Z.Li, A.P. Pisano, and R.S. Williams. Top-down fabricated silicon nanowire sensors for real-time chemical detection. Nanotechnology 21. 2010.