非晶矽薄膜電晶體及多晶矽薄膜電晶體已經用於製造液晶顯示器的畫素開關，尤其以非晶矽薄膜電晶體更是已經大量的運用在製造大面積的顯示面板。而因使用上的方便性，傳統的平面顯示器預估將被可曲撓式顯示器所取代。當非晶矽薄膜電晶體長時間操作在偏壓下時，元件的溫度會上升，因此探討其元件在不同溫度下可靠度的改變是十分重要的，另外，可曲撓示顯示器必須承受外加的機械應力。有鑑於此，本論文將研究非晶矽薄膜電晶體應用於可曲撓式顯示器在不同溫度、應力下可靠度的研究。
量測结果顯示，非晶矽的可靠度裂化程度直流偏壓的劣化明顯大於交流偏壓。為了探討兩種不同的劣化機制，我們利用能態密度的變化來探討。且由於其活化能會因不同的能態增加而不同，因此我們進一步利用變温量測粹取元件活化能(Ea)以確認非晶矽薄膜電晶體的裂化機制。
為了了解元件在不同溫度下劣化的程度，我們將元件在低溫(77K)、室溫(300K)、高溫(400K)下做可靠度的實驗。結果發現隨著溫度的提高，載子獲得的動能會越大，使的劣化更加嚴重。
最後在張應力下實驗，可以發現在受到張應力下的非晶矽薄膜電晶體較不受應力的非晶矽薄膜電晶體劣化更為嚴重，尤其交流偏壓下更為明顯，因此在彎曲的情形下其裂化機制和交流頻率呈現性關係和一般平面時有所不同。

Amorphous silicon thin film transistor(a-Si TFT) and poly silicon thin film transistor(p-Si TFT) have already been used for making the plain switch of picture of
the liquid crystal display, especially that amorphous silicon thin film transistor has been widely applied in the large area display panel. And the traditional display would be replaced by flexible display for the convenience. When the a-Si TFT device is operated for a long time, the temperature of the device will increase thereupon, t is very important to probe into the change of the reliability in different temperature, in
addition, flexible display should bear the extra mechanical stress. In view of this, we will research the reliability and electrical analyses of a-Si:H Thin Film Transistor under mechanical strain and varied temperature.
The result shows that the degradation of reliability of a-Si TFT under direct current is more serious than that of alternating current. , And we use the change of density of state (DOS) to probe the mechanism. Because the active energy varies with the DOS, we measured the device at different temperature to get the active energy (Ea) to confirm the main degradation mechanism for a-Si TFT.
In order to investigate the relationship of degradation and temperature, we stressed the device at low temperature (77K), room temperature (300K), and high temperature (400K), respectively.The result shows that the degradation is more serious at high temperature due to the higher energy of the carriers.
And we also found that the degradation of a-Si TFT under tensile bending is more serious than flatting, especially in alternating current stress. Thus, under bending condition the degradation mechanisms are dependent on frequency and different with flat condition.

Chinese Abstract……………………………………………...i
English Abstract……………………………………………..iii
Contents…………………………………………………….…v
Figures Captions…………………………………………… v
Chapter One
1.1 Introduction…………………………………………………1
1.1.1 Introduction……………………………………………………....1
1.1.2 Hydrogenated Amorphous Silicon…………………………………..2
1.1.3 Atomic Structure and the Electron Density of States………………..2
1.2 Substrate Material…………………………………………..3
1.2.1 Plastic Substrate………………………………………………………6
1.2.2 Metal Substrate…………………………………………………..…...7
1.2.3 Thin Glass Substrate………………………………………….……..9
1.3 Defined Bending Direction…………………….......................10
1.4 Motivation……………………………………………….…....10
Chapter Two
2.1 Apparatus………………………………………………......12
2.2 Setup instruments for I-V…………………………….….13
2.3 Method of Device Parameter Extraction………….……14
2.3.1 Determination of the threshold voltage……………………..…….14
2.3.2 Determonation of the subthreshold swing……………………..….14
2.3.3 Determination of the field-effect mobility…………………………15
2.4 Density of States……………………………………………17
Chapter Three
3.1 Deposition of Hydrogenated Amorphous Silicon by PECVD
………………………………………………………………19
3.2 Deposition of SiNx by PECVD…………………………….23
3.3 Deposition of n+ Hydrogenated Amorphous Silicon by PECVD
………………………………………………………………25
3.4 Process Flow………………………………………………..26
Chapter Four
4.1 Introduction…………..……………………………………….29
4.1.1Hydrogenated amorphous silicon…………………………………..….29
4.1.2 Bending experiment Discussion………………………………...…30
4.2Motivation
4.2.1 Hydrogenated amorphous silicon……………………………………30
4.2.2 Bending experiment………………………………………………30
4.3Experiments…………………………………………………...31
4.4 The Degradation of amorphous thin film transistor……….32
4.4.1 The constant bias stress…………………………………..…………….32
4.4.2. under pulse bias………………………………………………………...33
4.4.3 under different temperature……………………………………………35
4.4.4 Bending experiment…………………………………………………….36
Chapter Five
5.1 DC & AC Stress……………………………………………..37
5.2 Different temperature……………………………....……….37
5.3 Bending condition………...………………………………...37
Reference……………………………………………………..38
Figures………………………………………………………...46

Chapter One – Introduction
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of Information Display, p. 14 (1999).
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University, U.S.A. 2004.
7. W. H. Zachariasen, “The Atomic Arrangement in Glass, ” J. Am. Chem. Soc., 54, 3841
(1932).
8. W. E. Spear and P. G. LeComber, “Substitutional Doping of Amorphous Silicon, ”
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10. Y. Kuo, The Film Transistors – Material and Processes, vol. 2, p428, Texas A&M
University, U.S.A. 2004.
11. Y. Kuo, The Film Transistors – Material and Processes, vol. 2, p430, Texas A&M
University, U.S.A. 2004.
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13. Y. Kuo, The Film Transistors – Material and Processes, vol. 2, p430, Texas
A&M University, U.S.A. 2004.

Chapter Two – Apparatus and Parameters
1. R. A. Street, Hydrogenated Amorphous Silicon, Cambridge University Press, 1991.
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Amorphous Silicon by Transient and Steady-state Photoconductivity Measurement, ”
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5. J. D. Cohen, D. V. Lang, and J. P. Harbison, “Direct Measurement of the Bulk
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45 (3), 197 (1980).
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High-definition-display Technology, ” J. of the SID, 3-4, 223 (1995)
12. Y. Kuo, The Film Transistors – Material and Processes, vol. 1, p83, Texas A&M
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Chapter Three – Fabrication
1. W. M. M. Kessels, A. H. M. Smets, D. C. Marra, E. S. Aydil, D. C. Schram, and M.
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4. C. C. Tasi, G. B. Anderson, and R. Thompson, “ Growth of amorphous,
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5. J. Mort and F. Jansen, “Plasma-Deposited Thin Films,” p.28-33 (CRC Press, Boca
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6. F. J. Kampas and R. W. Griffith, “ Hydrogen elimination during the glow- discharge
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8. P. A. Longeway, “Semiconductors and Semimetals 21A,” pp.179-193 (In: J. I.
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10. R. Ishihara, H. Kanoh, Y. Uchida, O. Sugiura, and M. Matsumura,
“Low-temperature chemical vapor deposition of silicon nitride from tetrasilane and
hydrogen azide,” Mat. Res. Soc. Symp. Proc., vol.284, pp.3-8, 1992.
11. S. Yamakawa, S. Yabuta, A. Ban, M. Okamoto, M. Katayama, Y. Ishii, and M.
Hijikigawa, “The effect of plasma treatment on the off-current characteristics of a-Si
TFTs,” SID 98 Digest, pp.443-446, 1998.
12. K. Takechi, H. Uchida, and S. Kaneko, “Mobility-improvement mechanism in a-Si:H
TFTs with Smooth a-Si:H/SiNx Interface,” Mat. Res. Soc. Symp. Proc., vol.258,
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13. C. R. Kagan, P. Andry, The Film Transistors, p52-p57, IBM T. J. Watson Research
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14. M. C. Wang ,T. C. Chang, P. T. Liu, S. W. Tsao, and J. R. Chen, Electrochemical and
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Chapter Four – Bending experiment
1. R. Baeuerle, J. Baumbach, E. Lueder, and J. Siegordner, in SID’99 Digest, Society of
Information Display, p. 14 (1999).
2. S. D. Theiss and S. Wagner, IEEE Electron Device Lett. 17, 264 (1996)
3. M. Wu, K. Pangal, J. C. Sturm, and S. Wagner, Appl. Phys. Lett. 75, 2244(1999).
4. M.J.powell, C.van Berkel, and A.R.FranklinPhysical review B volume 45, number8
(1992)
5. Chun-Yao HUANG, Teh-Hung TENG, Jun-Wei TSAI Jpn. J. Appl. Phys. Vol. 39
(2000)
6. Navakanta Bhat, Min Cao, Member, IEEE TRANSACTIONS ON ELECTRON
DEVICES, VOL. 44, NO. 7, ( 1997)
7. M.J.powell, C.van Berkel, and I.D. French Physical review B volume 45, number8
(1987)