臺灣博碩士論文加值系統

在過去的15年之中，由於人類生活對於顯示器效能和大面積顯示器的需求愈發的提升，促進了在薄膜電晶體(Thin Film Transistor-TFT)技術上的蓬勃發展。提供互動式訊息功能的平面顯示器也已被快速的發展。為了在低花費下能夠跟上這種模式的轉變，並且保持薄和大面積的外型，以及高解析度，顯示器必須具有偵測器來接收外界訊號。為了滿足以上這些要素和達成許多技術上的挑戰，例如 : 讓主動式矩陣的開關TFT同時具有提供互動式的解決方法，因此，開始對於以TFT結構做為基底的高效能偵測器感到興趣。在下一代的顯示器中，較具有前景的方式是利用光偵測，因為只要光偵測器擁有高響應度、高偵測速度，是具有可以消除RC延遲的潛力。因為顯示器大多時間都放置於可見光下，結合可見光範圍的應用將是最直接方法。
本實驗是以溶膠凝膠法(sol-gel)的方式製作石墨烯奈米團聚物(以下稱石墨烯)作為光吸收層 ; 以非晶氧化銦鎵鋅(a-IGZO)作為半導體層，依conventional bottom-gate的電晶體結構所做成的可見光光電晶體。光電晶體可藉由本體的電晶體操作機制來得到高增益效果，所以基本a-IGZO TFT 的特性優劣將會影響作為光電晶體的感測能力。故本實驗將會於製程時調變不同的通道層厚度、調變不同的氧氣比率，並依照電特性之測試結果，選定較佳的元件作為光電晶體研究的基石。實驗結果發現為a-IGZO厚度40nm，製程氧氣比率0.2%為最佳的電晶體製程參數。除此之外，塗佈的石墨烯濃度過高或過低將會影響光電晶體的光激生載子數量，尤其是在近紫外光範圍(405nm)。實驗結果發現為石墨烯溶液濃度0.1wt%的光電晶體，其在可見光範圍的感測能力最佳，感測能力在VDS=10V，VGS=-1V，達124.3 A/W (405nm-7 mW/cm2)、1.8 A/W (532nm-5 mW/cm2)、0.058 A/W (650nm-4.5 mW/cm2)。在動態光感測的量測中，在短波長照射下(405nm)，由於石墨烯注入了額外的光激生電子，縮短了光感測元件對於光源的反應時間。

The last fifteen years have witnessed a phenomenal growth in thin film transistor (TFT) technology, driven by an insatiable demand for larger and larger displays. Indeed the flat panel display has been making rapid progress in providing interactive information retrieval as opposed to one-way information delivery. To keep up with this paradigm shift, the display must integrate in situ sensors to detect the external signal and yet maintain the thin and large area form factor, high resolution at low cost. In order to meet these myriad of technological challenges, there has been an active interest in high performance sensors based on the TFT structure, for process compatibility with the switching TFT in active matrix and offer the interactive solution. For the next generation display, a promising alternative is the photo sensing approach since it has the potential to eliminate RC delay issues, as long as the photo-sensor has high responsivity and high sensing speed enabling high frame rate applications. Most of the time because the displays are placed in visible light, the application in visible range is the most direct way.
In this work, we fabricated visible light phototransistors based on the integration of graphene nano-clusters(called graphene dots following) as light absorption layer by sol-gel and the active semiconductor layer of amorphous indium−gallium−zinc−oxide (a-IGZO) in conventional bottom-gate TFT configuration. Phototransistors can have high gain through the transistor action. So, performance of pristine a-IGZO TFTs will play an important role in graphene dots/a-IGZO phototransistors. Thus, we discussed electricity characteristics of a-IGZO TFTs depend on thicknesses of a-IGZO and oxygen ratio at deposition process. We discovered thicknesses 40nm and oxygen ratio 0.2% at deposition process are the best process conditions for a-IGZO TFT. In addition to the performance of a-IGZO, graphene dots concentration also a key to graphene dots/a-IGZO phototransisitors. Excessive and/or too little graphene dots concentration will effect the photogenerated carriers density in phototransistor, especially in the near ultraviolet range (405nm). We observed the phototransisitors were spin-coated graphene solution concentration 0.1wt%, exhibited the best sensing capability in the visible range. Under illumination, applied bias VDS = 10V and VGS = -1V. The photoresponsivity achieve 124.3 A/W in 405nm, 1.8 A/W in 532nm, and 0.058 A/W in 650nm. In dynamic photosensing measurement, under short-wave illumination(405nm), the response times is decreased , which is contributed to the photogenerated electrons inject from graphene dots.

誌謝 i
摘要 ii
Abstract iii
目錄 v
表目錄 viii
圖目錄 ix
第一章 緒論 1
1.1 光感測元件的應用 1
1.2 光感測元件種類 3
1.3 研究動機 4
第二章 文獻回顧 6
2.1 非晶氧化物半導體(Amorphous Oxide Semiconductor, AOS) 6
2.1.1 非晶氧化銦鎵鋅(Amorphous Indium Gallium Zinc Oxide) 9
2.1.2 a-IGZO 薄膜電晶體 11
2.2 光電晶體 11
2.3 石墨烯 12
2.4 重要參數 13
2.4.1 臨界電壓(Threshold voltage) 13
2.4.2 載子遷移率(Mobility) 13
2.4.3 次臨界擺幅(Subthreshold swing) 16
2.4.4 電流開關比(Ion/Ioff) 16
2.4.5 光響應度(Photoresponsivity) 17
2.4.6 光暗電流比(Photosensitivity) 18
第三章 實驗流程與步驟 19
3.1 實驗架構 19
3.2 玻璃基板之清洗 20
3.3 金屬電極製作 21
3.3.1 實驗儀器(Thermal evaporation) 21
3.3.2 實驗原理 21
3.3.3 實驗步驟 21
3.4 a-IGZO 薄膜濺鍍沉積 22
3.4.1 實驗儀器(Magnetron sputtering system) 22
3.4.2 實驗原理 22
3.4.3 實驗步驟 23
3.5 石墨烯 溶液及光吸收層製作 24
3.5.1 實驗儀器 24
3.5.2 實驗原理 24
3.5.3 實驗步驟 25
第四章 實驗結果與討論 26
4.1 a-IGZO 薄膜之光學特性 26
4.1.1 a-IGZO薄膜之穿透率 26
4.1.2 Tauc plot 分析a-IGZO之光學能隙 26
4.2 a-IGZO TFT之製作與特性分析 28
4.2.1 a-IGZO TFT之製作步驟及結構 28
4.2.2 變化通道層厚度對於a-IGZO元件特性之影響 30
4.2.3 變化製程時氧氣含量對於a-IGZO元件特性之影響 34
4.3 石墨烯 之特性分析 38
4.3.1 石墨烯塗佈後之形貌 38
4.3.2 石墨烯塗佈後之光學特性 41
4.3.3 石墨烯塗佈後之性質分析 43
4.4 Graphene dots/a-IGZO phototransistor之製作及特性分析 46
4.4.1 Graphene dots/a-IGZO phototransistor結構及製造 46
4.4.2 Graphene dots/a-IGZO phototransistor 光感測特性分析 49
4.4.3 動態光感測分析 63
第五章 結論 71
參考文獻 73

[1] 安毓英、曾小東，「光學感測與量測，」五南出版社，2004年。
[2] S.-E. Ahn, I. Song, S. Jeon, Y. W. Jeon, Y. Kim, C. Kim, B.i Ryu, J.-H. Lee , A. Nathan, S. Lee, G. T. Kim, and U-In Chung ,“Metal Oxide Thin Film Phototransistor for Remote Touch Interactive Displays,” Advance Material, vol. 24, pp. 2631–2636, 2012.
[3] J. S. Park, W.-J. Maeng, H.-S. Kim, J.-S. Park,“Review of recent developments in amor-phous oxide semiconductor thin-film transistor devices ,” Thin Solid Films, 520, pp. 1679–1693, 2012.
[4] Z. Pei, H.-C. Lai, J.-Y. Wang, W.-H. Chiang, and C.-H.Chen, “High-Responsivity and High-Sensitivity Graphene Dots/a-IGZO Thin-Film Phototransistor,” IEEE Electron Device Letters, vol.36, No.1, pp. 44-46, 2015.
[5] M.-K. Dai, Y.-R. Liou, J.-T. Lian, T.-Y. Lin, and Y.-F. Chen, “Multifunctionality of Giant and Long-Lasting Persistent Photoconductivity: Semiconductor−Conductor Transition in Graphene Nanosheets and Amorphous InGaZnO Hybrids,” ACS Photonics, vol. 2, pp. 1057−1064, 2015.
[6] R. R. Nair, P. Blake, A. N. Grigorenko, K. S. Novoselov, T. J. Booth, T. Stauber, N. M. R. Peres, A. K. Geim, “Fine Structure Constant Defines Visual Transparency of Graphene,” Science, vol. 320, pp.1308, 2008.
[7] H. Hosono, T. Kamiya, and M. Hirano, “Function cultivation of transparent oxide utilizing built-in nanostructures,” Bulletin of the Chemical Society of Japan, vol. 79, pp. 1-24, 2006.
[8] T. Kamiya and H. Hosono, “Creation of new functions in transparent oxides utilizing nanostructures embedded in crystal and artificially encoded by laser pulses,” Semiconduc-tor science and technology, vol. 20 pp. S92-S102, 2005.
[9] T. Kamiya and H. Hosono, “Material characteristics and applications of transparent amor-phous oxide semiconductor, ” NPG Asia Material, vol. 2, pp. 15-22, 2010
[10] H. Hosono, “Ionic amorphous oxide semiconductor: Material design, carrier transport, and device application,” Journal of Non-Crystalline Solids 352 ,pp. 851-858, 2006.
[11] T. Kamiya and H. Hosono, “Material characteristics and applications of transparent amor-phous oxide semiconductors,” NPG Asia Material, vol. 2, pp. 15-22, 2010.
[12] H. Hosono, M. Yasuk, H. Kawazoea, “Novel oxide amorphous semiconductors: transpar-ent conducting amorphous oxides,” Journal of Non-Crystalline Solids 203, pp. 334-344, 1996.
[13] K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, H. Hosono, “Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconduc-tors, ” Nature, vol. 432, pp. 488-492, 2004.
[14] J.-H. Shin, D.-K. Choi, “Effect of Oxygen on the Optical and the Electrical Properties of Amorphous InGaZnO Thin Films Prepared by RF Magnetron Sputtering,” Journal of the Korean Physical Society, Vol. 53, No. 4, pp. 2019-2023, 2008.
[15] J.-M. Lee, I.-T. Cho, J.-H. Lee1, and H.-I. Kwon, “Full-Swing InGaZnO Thin Film Tran-sistor Inverter with Depletion Load,” Japanese Journal of Applied Physics 48, pp. 100202, 2009.
[16] J.-S. Seo, J.-H. Jeon, Y. H. Hwang, H. Park, M. Ryu, S.-H. Ko Park and B.-S. Bae, “Solu-tion-Processed Flexible Fluorine-doped Indium Zinc Oxide Thin-Film Transistors Fabri-cated on Plastic Film at Low Temperature,” Scientific Reports, 3, pp. 2085, 2013
[17] Y. Kaneko, N. Koike, K. Tsutsui, and T. Tsukada, “Amorphous silicon phototransistors,” Appl. Phys. Lett., vol. 56, pp. 650-652, 2000.
[18] F. Yakuphanoglu, W. Aslam Farooq, “Flexible pentacene organic field-effect phototransis-tor” Synthetic Metals 161, pp. 379–383, 2011.
[19] Michael C. Hamilton, S. Martin, and J. Kanicki, “Thin-Film Organic Polymer Phototransis-tors,” IEEE Transactions on Electron Devices, vol. 51, No. 6, June, 2004.
[20] S. W. Shin, K.-H. Lee, J.-S. Park, and S. J. Kang, “Highly Transparent, Visble-Light Photodetector Based on Oxide Semiconductors and Quantum Dots,” ACS Appl. Mater. and Interface, vol. 7, pp. 19666−19671, 2015.
[21] S.-E. Ahn, S. Jeon, Y. W. Jeon, C. Kim, M.-J. Lee, C.-W. Lee, J. Park, I. Song, A. Nathan, S. Lee, and U-In Chung, “High-Performance Nanowire Oxide Photo-Thin Film Transistor, ” Adv. Mater., vol. 25, pp. 5549-5554, 2013.
[22] S. Han, W. Jin, D. Zhang, T. Tang, C. Li, X.i Liu, Z. Liu, B. Lei, C. Zhou, “Photoconduc-tion studies on GaN nanowire transistors under UV and polarized UV illumination,” Chemical Physics Letters 389, pp. 176–180, 2004.
[23] W. Guo, S. Xu, Z. Wu, N. Wang, M.M.T. Loy, and S. Du, “Oxygen-Assisted Charge Transfer Between ZnO Quantum Dots and Graphene,” Small, vol. 9, pp. 3031-3036, 2013.
[24] Z. Sun, Z. Liu, J. Li G. A. Tai, S. P. Lau, and F. Yan, “Infrared Photodetectors Based on CVD-Grown Graphene and PbS Quantum Dots with Ultrahigh Responsivity,” Adv. Mater., vol. 9, pp.5878-5883, 2012.
[25] K. Roy, M. Padmanabhan, S. Goswami, T. Sai, G. Ramalingam, S. Raghavan, and A. Ghosh, “Graphene-MoS2 hybrid structures for multifunctional photoresponsive memory devices,” Nature Nanotechnology, vol. 8, pp. 826-830, 2013.
[26] S. Y. Chen, Y. Y. Lu, F. Y. Shih, P. H. Ho, Y. F. Chen, C. W. Chen, Y. T. Chen, and W. H. Wang, “Biologically inspired graphene-chlorophyll phototransistors with high gain,” Carbon, vol. 63, pp. 23-29, 2013.
[27] D. Zhang, L. Gan, Y. Cao, Q. Wand, L. Qi, and X. Guo, “Understanding Charg Transfer at PbS-Decorated Graphene Surfaces toward a Tunable Phototransensor,” Advanced Mate-rials, vol. 24, pp.2715-2720, 2012.
[28] 王健宇，「低溫製作之非晶銦鎵鋅氧化物薄膜電晶體可靠性研究」，國立國立中興大學光電工程研究所碩士學位論文，2015年。
[29] Y. Chun, S. Chang, and S. Lee, “Effects of gate insulators on the performance of a-IGZO TFT fabricated at room-temperature” Microelectronic Engineering 88, pp. 1590–1593, 2011.
[30] A. C. Ferrari, J. C. Meyer, V. Scardaci, C. Casiraghi, M. Lazzeri, F. Mauri S. Piscanec, D. Jiang, K. S. Novoselov, S. Roth, and A. K. Geim, “Raman spectrum of Graphene and Graphene layer,” Physical Review Letters 97, pp. 187401, 2006.
[31] A. Gupta, G. Chen, P. Joshi, S. Tadigadapa, and P.C. Eklund, “Raman scattering from High-frequency Phonons in Supported n-Graphene layer films,” Nano Letter Vol.6, No. 12, pp. 2667-2673, 2006.
[32] K. Takechi, M. Nakata, T. Eguchi, H. Yamaguchi1, and S. Kaneko, “Comparison of Ultra-violet Photo-Field Effects between Hydrogenated Amorphous Silicon and Amorphous InGaZnO4 Thin-Film Transistors,” Japanese Journal of Applied Physics 48, pp. 010203, 2009.
[33] K. W. Lee, H. S. Shin, K. Y. Heo, K. M. Kim, and H. J. Kim, “Light Effects of the Amor-phous Indium Gallium Zinc Oxide Thin-Film Transistor,” Journal of Information Display, vol. 10, No. 4, pp. 171-174, 2009.
[34] Y. Lee, J. Kwon, E. Hwang, C.-H. Ra, W. Yoo, J. Ahn, J. Par, and J. Cho, “High-Performance Perovskite–Graphene Hybrid Photodetector” Adv. Mater., Vol 27, pp. 41–46, 2015.
[35] X. Liu, X. Yang, M. Liu, Z. Tao, Q. Dai, L. Wei, C. Li, X. Zhang, B. Wang, and A. Nathan, “Photo-modulated thin film transistor based on dynamic charge transfer within quantum-dots-InGaZnO interface,” Appl. Phys. Lett. 104, pp. 113501, 2014.