有機薄膜電晶體(OTFT)由於它的低成本、低溫製程，使得它足以廣泛地運用在電子產品上。然而由於介電層具有較大的表面極性，使得有機分子無法在介電層上排列的很好。而有機層的品質卻大幅地影響的元件的特性。
　　此本論文中著重在以化學處理下讓octadecyltrichlorosilane (OTS)在閘介層上形成一自主層（SAMs）。而在OTS幫助下使得界面間的缺陷減少，讓電晶體的特性改善。
　　首先我們製作上電極結構（Top contact）的有機薄膜電晶體以減低接觸電阻。以高參雜的導電矽基板當閘極，在基板上熱成長300nm 厚的二氧化矽介電層，然後熱蒸著70nm厚的五環素 (Pentacene)，最後鍍上金（Au）當汲極和源極金屬層，然而量測結果電晶體電特性的並不好。
於是在蒸鍍五環素(Pentacene)前，把已有熱成長二氧化矽的基板浸入溶有OTS的溶液中（分別在體積比0.1% OTS/十六烷及OTS/甲苯中）24小時，使得OTS在二氧化矽介電層上自主性地形成一薄膜層。結果發現電晶體的特性比起無化學處理時在載子移動率上（mobility）有十倍以上的改善，而次臨界斜率（subthreshold slope）也大幅的降低，電流開關比（on/off current ratio）也因而提升。
　　同樣的，改把基板浸入OTS/乙醇（體積比0.1%）的溶液中，結果發現特性並沒有太大的改善，原因是OTS的極性端（SiCl3）和乙醇產生反應，僅剩殘存的OTS能在二氧化矽介電層上形成自主層，而改把OTS/乙醇溶液的濃度增加到2%後，讓過多的OTS去形成自主層，因而電晶體特性有了改善。
　　為了要進一步去解釋實驗的結果，我們以接觸角量測（contact angle measurement），X光繞射（XRD），原子力顯微鏡（AFM）等量測儀器來分析OTS處理前後的差異性。
　　綜合上述所論，我們可以經由OTS處理的化學處理來改善有機主動層和介電層的介面特性，進而改善元件特性。

　　Organic thin-film transistors (OTFTs) are nowadays of interest for a wide range of electronic applications due to their low cost and low temperature process. However the large surface polarity of gate dielectric makes organic molecule not order very well. OTFT performance depends largely on the organic thin film quality.
　　In this thesis, we focused on the chemical modification with octadecyltrichlorosilane (OTS). OTS is always used in OTFTs, it forms self-assembled monolayers (SAMs) on gate dielectric. Interface defects can be reduced with the assist of OTS, and the characteristics of OTFTs will be improved.
　　Firstly, OTFTs devices were fabricated with top contact structure in order to minimize contact resistance. The gate electrode was a heavily doped Si wafer with 300 nm of thermally grown SiO2 as the gate dielectric and pentacene was thermally evaporated with 70nm and finally gold was thermally evaporated as drain/source electrode. But the results were poor.
　　Thus, prior to the deposition of the pentacene, the substrates with thermally grown SiO2 were immersed in octadecyltrichlorosilane (OTS) solution (V/V 0.1% in n-hexadecane and toluene) to form a monolayer on the surface of silicon dioxide. The performance of OTFTs typically show a factor of 10 improvement in field-effect mobility and reduced subthreshold slope when using gate dielectric chemically treated with OTS compared to OTFTs on untreated gate dielectric. And on/off current ratio also increases greatly.
　　Substrates were also immersed in OTS solution (V/V 0.1% in ethanol), but the results showed poor improvement compared with OTFTs on untreated gate dielectric. This is because that polar head group (SiCl3) of OTS reacts with ethanol and only a little OTS left to form SAMs on gate dielectric. If increasing the concentration of OTS solution (V/V 2% in ethanol), the results were greatly improved.
In order to explain our experiments results, atomic force microscope, X-ray diffraction and contact angle measurement were used to analyze the characteristics of OTS treated and untreated gate dielectric.
　　To conclude, we can use of silicon dioxide gate chemically modified with octadecyltrichlorosilane (OTS) monolayers to improve the interface between organic semiconductor and dielectric resulting in the better performance of organic thin film transistors.

[1] J. E. Lilienfeld, US Patent 1 745 175, (1930).
[2] D. Kahng, M. M. Atalla, IRE Solid-State Devices Research Conference, Carnegie Institute of Technology, Pittsburgh, PA (1960).
[3] D. F. Barbe, C. R. Westgate, J. Phys. Chem. Solids, 31, 2679 (1970).
[4] M. L. Petrova, L. D. Rozenshtein, Fiz. Tverd. Tela (Sov. Phys.-Solid State) 12, 961 (1970).
[5] F. Ebisawa, T. Kurokawa, S. Nara, J. Appl. Phys. 54, 3255 (1983).
[6] C. D. Dimitrakopoulos, D. J. Mascaro IBM J. RES. & DEV. Vol. 45 No. 1 (2001)
[7]Y. Taur and T. H. Ning, Fundamentals of Modern VLSI Devices, Cambridge University Press, New York, 1998, p. 11.
[8] K. Schleupen, P. Alt, P. Andry, S. Asaad, E. Colgan, P. Fryer,
Proceedings of the 18th International Display Research Conference, Asia Display ’98, pp. 187–190 (1998).
[9]W. Riess, H. Riel, T. Beierlein, W. Bru¨tting, P. Mu¨ller, and P. F. Seidler, IBM J. Res. & Dev. 45, 77 (2001, this issue).
[10]R. Friend, J. Burroughes, and T. Shimoda, “Polymer Diodes,” Phys. World (UK) 12, 35 (1999).
[11] A. Tsumura, H. Koezuka, and T. Ando, Appl. Phys. Lett., vol. 49, no. 18, pp. 1210–1212, (1986).
[12] J. H. Burroughes, C. A. Jones, and R. H. Friend, Nature, vol. 335, pp. 137–141, (1988).
[13] G. Horowitz, D. Fichou, X. Peng, Z. Xu, and F. Garnier, Solid State Commun., vol. 72, pp. 381–384, (1989).
[14] F. Garnier, R. Hajlaoui, A. Yassar, and P. Srivastava, Science, vol. 265, pp. 1684–1686, (1994).
[15] J. G. Laquindanum, H. E. Katz, A. J. Lovinger, and A. Dodabalapur, Chem. Mater., vol. 8, no. 11, pp. 2542–2544, (1996).
[16] A. Tsumura, H. Koezuka, and T. Ando, “Macromolecular Electronic Device: Field-Effect Transistor with a Polythiophene Thin Film,” Appl. Phys. Lett. 49, 1210 (1986).
[17] J. H. Burroughes, C. A. Jones, and R. H. Friend, Nature 335, 137 (1988).
[18] C. Clarisse, M. T. Riou, M. Gauneau, and M. Le Contellec, Electron. Lett. 24, 674 (1988).
[19] A. Assadi, C. Svensson, M. Willander, and O. Ingana¨s, Appl. Phys. Lett. 53, 195 (1988).
[20] J. Paloheimo, E. Punkka, H. Stubb, and P. Kuivalainen, in Lower Dimensional Systems and Molecular Devices, Proceedings of NATO ASI, Spetses, Greece, R. M. Mertzger, Ed., Plenum Press, New York, (1989).
[21] G. Horowitz, X. Peng, D. Fichou, and F. Garnier, Synth. Met. 51, 419 (1992).
[22] F. Garnier, A. Yassar, R. Hajlaoui, G. Horowitz, F. Dellofre, B. Servet, S. Ries, and P. Alnot, J. Amer. Chem. Soc. 115, 8716 (1993).
[23] A. Dodabalapur, L. Torsi, and H. E. Katz, “Science 268, 270 (1995).
[24] Y.-Y. Lin, D. J. Gundlach, and T. N. Jackson, 54th Annual Device Research Conference Digest, p. 80 (1996).
[25] R. C. Haddon, A. S. Perel, R. C. Morris, T. T. M. Palstra, A. F. Hebard, and R. M. Fleming, Appl. Phys. Lett. 67, 121 (1995).
[26] H. E. Katz, A. J. Lovinger, J. Johnson, C. Kloc, T. Siergist, W. Li, Y.-Y. Lin, and A. Dodabalapur, Nature 404, 478 (2000).
[27] Yen-Yi Lin, Student Member, IEEE, David J. Gundlach, Shelby F. Nelson, and Thomas N. Jackson, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol. 44, No 8, (1997)
[28] G. Horowitz, Adv. Mater. 10, No. 5, (1998)
[29] M. Shur, Physics of Semiconductor Devices, Prentice-Hall, Englewood Cliffs, pp. 437-446 (1990)
[30]David J. Gundlach, LiLi Jia ,Thomas N. Jackson, ,IEEE Electron Device Letters, vol. 22, No. 12.
[31] Biotechnology and Biongineering, Vol. 83, No 4, 20, (2003)