臺灣博碩士論文加值系統

本次研究探討五環素薄膜電晶體輸出特性與轉換特性曲線所萃取的遷移率不一致之原因，轉換特性曲線所萃取的遷移率較輸出特性曲線高，由實驗結果顯示是由於電容變化導致汲極電流增加使得遷移率被高估，且由此實驗發現由於延遲時間量測造成的電荷陷捕對元件特性的影響，由於五環素薄膜內電洞陷捕的影響，使得單位時間的汲源極電壓的變化造成遷移率改變，而五環素與絕緣層界面的電子陷捕，使單位時間的閘極電壓變化造成臨界電壓改變。在本研究中利用氧電漿處理提升五環素薄膜電晶體的元件特性，氧電漿處理後使臨界電壓改變與遷移率增加，臨界電壓改變是由於電子陷捕增加，遷移率的增加是由於氧原子鈍化晶界缺陷導致，且由於元件由長壽命電子陷捕作主導，使得五環素薄膜電晶體元件穩定性提高。

關鍵字：五環素、薄膜電晶體、氧電漿

The discrepancy in mobility (μsat) extracted from transfer and output characteristics of organic thin film transistors was studied. The extraction from transfer characteristics demonstrates higher μsat, compared to the extraction from output characteristics. It is shown that the contribution of capacitance variation may lead to an increased drain current, thus overestimating μsat. A simple technique (that is, measurements with and without an additional delay) to find the conduction behavior for pentacene thin film transistors was developed in this study. It is shown that the drain-source voltage variation may lead to a change in the μsat, owing to hole trapping in the pentacene film. In addition, the gate-source voltage variation may lead to a shift of the threshold voltage (VTH), owing to electron trapping at the pentacene/dielectric interface. These facts point to a change in μsat (a shift of VTH) that is bulk (interface) related rather than interface (bulk) related. The effect of the induced electron traps by oxygen plasma treatment on transfer characteristics of organic thin film transistors (OTFTs) was researched in this study. From the observed result, the relationship between electron trapping and electrical stability of OTFTs was discussed. It is shown that oxygen plasma treatment may lead to a shift of the VTH towards positive gate-source voltages and an increase in the μsat, resulting from the incorporation of oxygen and the passivation of the defects in the grain-boundary region. It is found that the electrical stability mainly arises from the increased long-lifetime electron-trap density.

Keywords：Pentacene、Thin film transistors、Oxygen plasma

目 錄
中文摘要 I
英文摘要 II
誌謝 III
目錄 IV
圖目錄 VI
表目錄 VIII
第一章　緒論
1-1　有機光電元件介紹 1
1-2 有機半導體材料簡介 3
1-2.1 五環素的基本性質 6
1-3 有機薄膜電晶體 8
1-3.1 有機薄膜電晶體的基本公式與特性 10
1-4 研究動機 11
第二章 實驗儀器與儀器原理
2-1 熱氧化原理 12
2-2 熱蒸鍍系統 13
2-3 直流濺鍍系統 14
2-4 電流-電壓量測系統 16
2-4.1 輸出特性量測法 17
2-4.2 轉換特性量測法 18
2-4.3 時間相關量測法 19
2-4.4 單位時間電壓變化量設定 20
第三章 實驗步驟
3-1 研究架構與流程 22
3-2 有機薄膜電晶體元件實驗流程 23
第四章 實驗結果與討論
4-1 輸出特性與轉換特性之電特性分析 26
4-2 延遲時間對元件特性影響分析 31
4-3 電荷陷捕機制的探討 37
4-3.1 氧電漿處理對電荷陷捕機制的影響 38
第五章 結論 43
第六章 參考文獻 45
圖目錄
圖1-1.1、第一顆點接觸電晶體(a)成品圖與(b)元件示意圖 2
圖1-2.1、有機半導體種類有(a)小分子材料(b)高分子材料以及(c)有機金屬錯合物示意圖 4
圖1-2.2、載子在有機半導體跳躍機制有(a)多晶結構跳躍機制和(b)單晶結構跳躍機制 5
圖1-2.1-1、(a) PEN之化學結構示意圖與(b) PEN之LUMO與HOMO能階 7
圖1-3.1、以P型有機半導體為主動層的 (a)增強模式與(b)空乏模式OTFTs元件 9
圖2-1.1、管狀爐示意圖 12
圖2-2.1、熱蒸鍍系統示意圖 13
圖2-3.1、直流濺鍍系統示意圖 15
圖2-4.1、電流-電壓量測機台型號為吉時利Model-4200-SCS 16
圖2-4.1-1、輸出特性曲線量測示意圖 17
圖2-4.2-1、轉換特性曲線量測示意圖 18
圖2-4.3-1、時間電流量測示意圖 19
圖2-4.4-1、吉時利 Model-4200-SCS系統電流-電壓掃描量測原理示意圖 21
圖3-1.1、實驗架構流程 22
圖3-2.1、OTFTs元件的(a)剖面圖(b)俯視圖 25
圖4-1.1、OTFTs輸出特性曲線 28
圖4-1.2、(a)VDS= -40 V時OTFTs轉換特性曲線以及(b)由圖4-1.1VDS= -40 V的ID對VGS擬合曲線 28
圖4-1.3、 (a)取自圖4-1.2(a)與(b)取自圖4-1.2(b)經轉換成的|ID,sat|0.5-VGS關係圖 29
圖4-1.4、Au/PEN/SiO2/N+-Si在±5, ±10與±40 V的遲滯I-V圖 30
圖4-1.5、(a)無延遲(b)延遲0.2秒以及(c)延遲0.4秒之|ID,sat|0.5-VGS關係圖 30
圖4-2.1、OTFTs於延遲0秒、延遲0.2秒、延遲0.4秒與延遲0.6秒所觀測之轉換特性曲線 33
圖4-2.2、由轉換特性曲線所萃取之μsat與VTH與延遲時間關係圖 33
圖4-2.3、OTFTs延遲(a)0秒(b)0.2秒(c)0.4秒(d)0.6秒所觀測之輸出特性曲線 34
圖4-2.4、由輸出特性曲線於VDS=-40 V的ID對VGS擬合曲線 35
圖4-2.5、由輸出特性曲線所萃取之μsat與VTH與延遲時間關係圖 35
圖4-2.6、電洞陷捕示意圖(□表示電洞陷捕，⊕為電洞，→表是電洞的移動方向) 36
圖4-3.1-1、(a)氧電漿處理前與(b)氧電漿處理後之|ID,sat|0.5-VGS關係圖 40
圖4-3.1-2、(a)氧電漿處理前與(b)氧電漿處理後有無延遲|ID|0.5-VGS關係圖 41
圖4-3.1-3、(a)氧電漿處理前與(b)氧電漿處理後之時間-電流量測圖 42
表目錄
表1-2.1-1、PEN 的基本性質 7
表4-1.1、OTFTs元件擬合數據 29
表4-3.1-1、氧電漿處理前後之μsat與VTH 40
表4-3.1-2、時間-電流量測之擬合參數 42

[1] J. Bardeen and W. H. Brattain, “The transistor a semiconductor triode,” Phys. Rev. 74, 230 (1948).
[2] H. Xiao, “Introduction to Semiconductor Manufacturing Technology,” (Prentice Hall, Englewood Cliffs, 2001).
[3] 河村正行 著；趙忠興 譯，有機EL 顯示面板的原理與技術(全華科技圖書股份有限公司，臺北市，2005)。
[4] 2009 年機光股份有限公司材料表(http://www.lumtec.com.tw/)。
[5] G. Horowitz, M. E. Hajlaoui, and R. Hajlaoui, “Temperature and gate voltage dependence of hole mobility in polycrystalline oligothiophene thin film transistors,” J. Appl. Phys. 87, 4456 (2000).
[6] D. Knipp and R. A. Street, “Pentacene thin film transistors on large area compatible gate dielectrics,” J. Non-Cryst. Solids 338, 595 (2004).
[7] W. Park, K. J. Baeg, J. Ghim, S. J. Kang, J. H. Park, and D. Y. Kim, “Effects of copper oxide/gold electrode as the source-drain electrodes in organic thin-film transistors,” Electrochem. Solid-State Lett. 10, 340
(2007).
[8] P. Parisse, M. Passacantando, and L. Ottaviano, “Morphological and electronic properties of the thin film phase of pentacene investigated by AFM and STM/STS,” Appl. Surf. Sci. 252, 7469 (2006).
[9] D. Guo, S. Entani, S. Ikeda, and K. Saiki, “Effect of UV/ozone treatment of the dielectric layer on the device performance of pentacene thin film transistors,” Chem. Phys. Lett. 429, 124 (2006).
[10] C. Bock, D. V. Pham, U. Kunze, D. Käfer, G. Witte, and C. Wöll,“Improved morphology and charge carrier injection in pentacene field-effect transistors with thiol-treated electrodes ,” J. Appl. Phys. 100, 114517 (2006).
[11] T. Ahn, H. Jung, H. J. Suk, and M. H. Yi, “Effect of postfabrication thermal annealing on the electrical performance of pentacene organic thin-film transistors,” Synth. Met. 159, 1277 (2009).
[12] W. Y. Chou, C. W. Kuo, H. L. Cheng, Y. R. Chen, F. C. Tang, F. Y. Yang, D. Y. Shu, and C. C. Liao, “Effect of surface free energy in gate dielectric in pentacene thin-film transistors,” Appl. Phys. Lett. 89, 112126 (2006).
[13] B. Razavi, “Fundamentals of Microelectronics,” (Wiley, New York 2008)
[14] M. Shur, “Physics of Semiconductor Devices,” (Prentice-Hall, Englewood Cliffs, 1990).
[15] D. A. Neamen, “Semiconductor Physics and Devices,” (McGraw-Hill, New York, 2003).
[16] H. S. Majumdar, A. Bandyopadhyay, A. Bolognesi, and A. J. Pal, “Memory device applications of a conjugated polymer:Role of space charges,” J. Appl. Phys. 91, 2433 (2002).
[17] Y. J. Lin, “Hysteresis-type current-voltage characteristics of indium tin oxide/poly (3,4-ethylenedioxythiophene) doped with poly (4-styrenesulfonate)/indium tin oxide devices,” J. Appl. Phys. 103, 063702 (2008).
[18] Y. J. Lin, P. H. Wu, C. L. Tsai, C. J. Liu, Z. R. Lin, H. C. Chang, and C. T. Lee, “Effects of Mg incorporation on the optical properties of ZnO prepared by the sol-gel method,” J. Appl. Phys. 103, 113709 (2008).
[19] J. Lee, J. H. Kim, S. Im, and D. Y. Jung, “Threshold voltage change due to organic-inorganic interface in pentacene thin-film transistors,” J. Appl.Phys. 96, 2301 (2004).
[20] W. A. Schoonveld, J. B. Oostinga, J. Vrijmoeth, and T. M. Klapwijk, “Charge trapping instabilities of sexithiophene Thin Film Transistors,” Synth. Met. 101, 608 (1999).
[21] A. R. Völkel, R. A. Street, and D. Knipp, “Carrier transport and density of state distributions in pentacene transistors,” Phys. Rev. B 66, 195336 (2002).
[22] T. Manaka, H. Kohn, Y. Ohshima, E. Lim, amd M. Iwamoto, ” Hole trapping in polydiacetylene field effect transistor studied by optical second harmonic generation,” Thin Solid Film 516, 2779 (2008).
[23] S. D. Wang, T. Minari, T. Miyadera, K. Tsukagoshi, Y. Aoyagi, “Contact-metal dependent current injection in pentacene thin-film transistors,” Appl. Phys. Lett. 91 203508 (2007).
[24] T. Minari, T. Miyadera, K. Tsukagoshi, Y. Aoygi, “Charge injection process in organic field-effect transistors,” Appl. Phys. Lett. 91 053508 (2007).
[25] G. Gu, M. G. Kane, J. E. Doty, and A. H. Firester, “Electron traps and hysteresis in pentacene-based organic thin-film transistors,” Appl. Phys. Lett. 87, 243512 (2005).
[26] C. Ucurum, H. Goebel, F. A. Yildirim, W. Bauhofer, and W. Krautschneider, “Hole trap related hysteresis in pentacene field-effect transistors,” J. Appl. Phys. 104, 084501 (2008).
[27] J. B. Chang and V. Subramanian, “Effect of active layer thickness on bias stress effect in pentacene thin-film transistors,” Appl. Phys. Lett. 88, 233513 (2006).
[28] C. S. Lin and Y. J. Lin, “Enhancement of the hole mobility and concentration in pentacene by oxygen plasma treatment,” J. Non-Cryst.Solids 356, 2832 (2010).
[29] D. Knipp, R. A. Street, A. Völkel, and J. Ho, “Pentacene thin film transistors on inorganic dielectrics: Morphology, structural properties, and electronic transport,” J. Appl. Phys. 93, 347 (2003).
[30] V. Nádaždy, R. Durný , J. Puigdollers, C. Voz, S. Cheylan, and K. Gmucová, “Experimental observation of oxygen-related defect state in pentacene thin films,” Appl. Phys. Lett. 90, 092112 (2007).
[31] D. Knipp, T. Muck, A. Benor, and V. Wagner, “Environmental stability and electronic transport of pentacene thin film transistors,” J. Non-Cryst. Solids
352,1774 (2006).
[32] Y. J. Lin, ” Leakage conduction mechanism of top-contact organic thin film transistors,” Synth. Met. 160, 2628 (2010).
[33] D. Knipp, A. Benor, V. Wagner, and T. Muck, ”Influence of impurities and structural properties on the device stability of pentacene thin film transistors,” J. Appl. Phys. 101, 044504 (2007).