在此論文中，我們深入討論使用ITO電極有機薄膜電晶體的溫度效應與照光效應。
實驗結果顯示有機薄膜電晶體開啟時的特性與溫度變化有關。此外，發現有機薄膜電晶體也是一種光偵測器。外在條件也會影響我們的I-V特性。例如，有機薄膜電晶體的啟始電壓會因照光效應而產生飄移的現象，照光之後置於黑暗中電晶體特性會隨時間緩慢的恢復到原始狀態。因此，除了在一般開關元件的應用上，在影像感測器上的應用上也具有極大的潛力。

In this work, we have investigated the effects of temperature and optical illumination on organic thin film transistors (OTFTs) with indium-tin-oxide electrode.
Experimental results have shown that the turn-on characteristics of the pentacene OTFT with ITO as source/drain electrodes is dependent on environmental temperatures. In addition, it has been found the pentacene OTFT is one kind of photo-sensitive devices. External stimulations can change the I-V characteristics significantly. For example, our pentacene OTFT show a shift of the onset and threshold voltage with illumination, which recovers slowly in the dark. Therefore, except for the application of switch devices, petacene OTFT exhibits a potential application for image sensors.

Contents
Chapter 1 introduction
1.1 Historical perspective………………………………………………………..1
1.2 Charge transport of organic semiconductor……………………………....3
1.2.1 Hopping transport………………………………………………..……7
1.2.2 Multiple trapping and release model…………………..……………8
1.2.3 Polarons………………………………………………………...…….10
1.3 Motivation……………………………………………………………………11
1.4 Organization of This Thesis………………………………………......…..12
Chapter 2
2.1 Device fabrication………………………………………………..………...13
2.2 Organic thin film transistor operation……………………………..……..14
2.2.1 Parameter extraction………………………………………..………17
2.2.2 Contact resistance for organic thin film transistor…………..……19
Chapter 3 Illumination effect on OTFTs
3.1Different intensity of illumination on OTFTs………………………….….22
3.2 VT depended on illumination and drain voltage…………………...…….23
3.3 Reversible light-induced threshold voltage shift………………………...26
Electron trapping model……………………………………………..…….27
3.4 Illumination increasing Rcontact and Rchannel………………………..28
Summary……………………………………………………………….………30
Chapter 4 Bias stress effects on OTFTs
4.1 Electrical characteristics after ac bias stress………………..…………..32
4.2 Electrical characteristics after positive dc bias stress…………………..33
4.3 Electrical characteristics after negative dc bias stress……..…………..34
Summary…………………………………………………………...……………35
Chapter 5 Variable-temperature effects
5.1 Channel resistance as a function of temperature………………..……..37
5.2 Variable-temperature measurements (Low temperature and hight temperature) ………….. ………………………………………..………..39
Summary……………………………………………………………...…………43
Chapter 6 Conclusion……………………………………………….…………..45
Reference……………………………………………………………………….…46

Reference
chapter1.1
【1】H. Bassen, W. H. Bratain. The transistor, a semi conductor triode. Phys Rev 74: 730-731 (1948)
【2】H. Reisch, W. Wiesler, U. Scherf and N. Tuytuylkov, Macromolecules 29, 8204 (1996).
【3】G. A. Chamberlain. Organic solar cells, a review. Solar Cells 10: 47-83 (1983)
【4】F. Ebisawa, T. Kurosawa. Electrical properties of Polyacetylene/polysilox and interface. J. Appl Phys 54: 3255-3259 (1983)
【5】J. H. Burroughes, C. A. Jones. Field-enhanced conductivity in polyacetylene-construction of a field-effect transistor. J Phys D Appl Phys 22: 956-958 (1989)
【6】F. Garnier, G. Horowitz. Adv Mater 2: 592-594 (1990)
【7】L. Torsi, A. Dodabalapur, L. J. Rothberg, A. W. P. Fung, and H. E. Katz,
Science 272, 1462 (1996).
【8】Y. Y. Lin, D. J. Gundlach, S. F. Nelson, and T. N. Jackson, IEEE Trans.
Electron Devices 44, 320 (1997).
【9】H. Sirringhaus, N. Tessler, and R. H. Friend, Science 280, 1741 (1998).
【10】C. D. Sheraw, L. Zhou, J. R. Haung, D. J. Gundlach, T. N. Jackson, M. G. Kane, I. G. Hill, M. S. Hammond, J. Campi, B. K. Greening, J. Francl, and J. West, Appl. Phys. Lett. 80, 1088 (2002).
【11】M. Shtein, J. Mapei, J. B. Benziger, and S. R. Forrest, Appl. Phys. Lett.
81, 268 (2002).

chapter1.2
【12】H. Fuchigami, A. Tsumura, and H. Koezuka, Appl. Phys. Lett. 63, 1372 (1993).
【13】M. Matters, D. M. de Leeuw, P. T. Herwig, and A. R. Brown, Synth. Met. 102, 998
(1999).
【14】E.J. Meijer, C. Tanase, P.W.M. Blom, E. van Veenendaal, B.-H. Huisman, D.M. de
Leeuw, and T.M. Klapwijk, Appl. Phys. Lett. 80, 3838 (2002).
【15】M. Shur and M. Hack, J. Appl. Phys. 55, 3831 (1984).
【16】S. Luan and W. Neudeck, J. Appl. Phys. 72, 766 (1992).
【17】H. Sirringhaus, N. Tessler, D.S. Thomas, P.J. Brown, and R.H. Friend, Festk¨orperprobleme 39, 101 (1999).
【18】L. Torsi, A. Dodabalapur, and H.E. Katz, J. Appl. Phys. 78, 1088 (1995).
【19】G. Horowitz, R. Hajlaoui, D. Fichou and A. El Kassmi, J. Appl. Phys. 6, 3202, (1999).
【20】Y.Y. Lin, D.J. Gundlach, and T.N. Jackson, Mat. Res. Soc. Symp. Proc. 413, 413
(1996).
【21】K. Terada and H. Muta, Jap. J. Appl. Phys. 18, 953 (1979).
【22】J.G.J. Chern, P. Chang, R.F. Motta and N. Godinho, IEEE Elect. Dev. Lett. 1, 170
(1980).
【23】T. van Woudenbergh, P.W.M. Blom, M.C.J.M. Vissenberg and J.N. Huiberts, Appl.
Phys. Lett. 79, 1697 (2001).
【24】Y. Shen, M.W. Klein, D.B. Jacobs, J.C. Scott and G.G. Malliaras, Phys. Rev. Lett.
86, 3867 (2001).

chapter1.3
【25】C. C.Wu, S. D. Theiss, G. Gu, M. H. Lu, J. C. Sturm, S.Wagner, and S.R. Forrest, “Integration of organic LEDs and amorphous Si TFTs onto flexible and lightweight metal foil substrates,” IEEE Electron Device Lett., vol. 18, pp. 609–612, Dec. (1997)
【26】G. B. Blanchet, J. A. Rogers, Y. -L. Loo, F. Gao, C. R. Fincher, and D. E. Wilmington, “Large area printing of organic transistors via a high throughput dry process,” in Proc. Mater. Res. Soc. Symp., vol. 736, pp. D6.4–D6.4, (2002)
【27】S. K. Park, Y. H. Kim, J. I. Han, D. G. Moon, and W. K. Kim, “High performance
polymer TFTs printed on a plastic substrate,” IEEE Trans. Electron Devices, vol. 49, pp. 2008–2015, Feb. (2002)
【28】J. H. Schon and B. Batlogg, Modeling of the temperature dependence of the field-effect mobility in thin film devices of conjugated oligomers, APL, VOLUME 74, NUMBER 2, (1999)
【29】Paul V. Pesavento, Reid J. Chesterfield, Christopher R. Newman, Gated four-probe measurements on pentacene thin-film transistors: Contact resistance as a function of gate voltage and temperature, JOURNAL OF APPLIED PHYSICS VOLUME 96, NUMBER 12,(2004)
【30】J.H. Schon, Ch. Kloc, B. Batlogg, On the intrinsic limits of pentacene field-effect transistors, Organic Electronics 1 57－64, (2000)
【31】S. F. Nelson, Temperature-independent transport in high-mobility pentacene transistors ,APL, VOLUME 72, NUMBER,(1998)
【32】Gilles Horowitz, Temperature and gate voltage dependence of hole mobility in polycrystalline oligothiophene thin film transistors, JOURNAL OF APPLIED PHYSICS VOLUME 87,(2000)
【33】Tsuyoshi Sekitani, Pentacene field-effect transistors on plastic films operating at high
temperature above 100 °C, APL VOLUME 85, NUMBER 17 ,(2004)
【34】A. R. Vo¨lkel, R. A. Street, and D. Knipp,” Carrier transport and density of state distributions in pentacene transistors”, PHYSICAL REVIEW B 66, 195336(2002)
【35】Yan Liang, Guifang Dong, Yan Hu, Liduo Wang, and Yong Qiu, “Low-voltage pentacene thin-film transistors with Ta2O5 gate insulators and their reversible light-induced threshold voltage shift”, APL,86, 132101(2005)
【36】Jiyoul Lee, S. S. Kim, Kibum Kim, Jae Hoon Kim, Correlation between photoelectric and optical absorption spectra of thermally evaporated pentacene films, APL VOLUME 84, NUMBER 10(2004).
【37】D.J. Gundlach, L. Zhou, Organic thin film phototransistors and fast circuits, IEEE IEDM 01-743(2001).
【38】Jan Hendrik Scho¨n, Christian Kloc, Organic metal–semiconductor field-effect phototransistors, APL VOLUME 78, NUMBER 22(2001).
【39】Reid J. Chesterfield, “ Variable Temperature Film and Contact Resistance Measurements on Operating N-Channel Organic Thin Film Transistors”, J. Appl. Phys., volume 95, number 11(2004).
【40】D. Knipp, “Pentacene thin film transistors on Inorganic Dielectrics: Morphology, Structure Properties, and electronic Transport”, J. Appl. Phys., volume 93, number 1 (2003).

Chapter2.2
【41】Cherie R.Kagan, Paul Andry, THIN-FILM TRANSISTORS, MARCEL DEKKER, INC.
【42】G. Horowitz, R. Hajlaoui, H. Bouchriha, R. Bourguiga, and M. Hajlaoui,
Adv. Mater. 10, 923 (1998).
【43】Jana Zaumseil, Kirk W. Baldwin, and John A, Contact resistance in organic transistors that use source and drain electrodes formed by soft contact lamination, JOURNAL OF APPLIED PHYSICS VOLUME 93, NUMBER 10(2003)
【44】Peter V. Necliudov , Michael S. Shur , David J. Gundlach, Thomas N. Jackson, Contact resistance extraction in pentacene thin film transistors, Solid-State Electronics 47 ,259–262 (2003)