本次實驗的目的為利用石墨烯偵測乙醇溶液。藉由將石墨烯浸泡至不同濃度的乙醇溶液中，由於石墨烯表面會吸附乙醇溶液分子，造成表面位能改變，進而影響載子的傳輸，電阻會隨著濃度越大而變化越大。隨著將石墨烯從乙醇溶液中取出，石墨烯會因表面的乙醇溶液分子揮發而電阻遞減，將電阻隨時間變化的數據，利用Polanyi-Wigner equation進行分析，可以求得乙醇溶液的揮發速率，乙醇溶液濃度越高則揮發速率越低。為了釐清表面缺陷結構對乙醇溶液吸附能力的影響，利用三個大小相同，起始電阻不同的石墨烯進行實驗，起始電阻的不同是因為石墨烯表面結構缺陷的差異造成的，這些結構缺陷會與溶液分子形成半化學鍵，這些化學鍵結會對載子傳輸造成影響，且化學鍵結對載子的影響大於物理吸附，所以起始電阻越大的石墨烯片，缺陷結構越多，電阻變化越大。為了消除因為石墨烯表面溶液殘留造成電阻變化最大值改變的因素，將同一片石墨烯進行多次實驗，藉由量測石墨烯的電阻控制表面的殘留量，將不同溶液殘留量的石墨烯進行實驗，由於石墨烯表面可吸附的溶液量為固定值，所以殘留量越多時，石墨烯的起始電阻越大，電阻變化最大值就越小。

We use graphene sheets to detect the ethanol. Due to the ethanol molecules adsorbed on graphene sheets, these molecules induce local potential wells on graphene sheets. That will affect on the carrier transport properties. The resistance change is proportional to the ethanol concentration. The dynamic response of evaporation is traced. It shows that the resistance decays because of the ethanol molecules desorption. We use Polanyi-Wigner equation fitting, and we obtain the desorption rate. The higher ethanol concentrations make the slower desorption rate. To clarify the influence of the structure defects on the graphene surface on the ability of adsorption, three sample with same size but different amount of structure defects are prepare to identify the behaviors. The structure defects perform semi-chemical bonding with the ethanol molecules. This bonding influence on carrier transport and that is much stronger than physical adsorption. Thus, the higher resistance change is observed in graphene sheets with more structure defects. To eliminate the influence of the residual adsorbed ethanol molecules on graphene sheets, the graphene sheet with different amount of the residual adsorbed molecules is prepared. The unoccupied surface space directly relates to the ability for the extra adsorbed molecules on the graphene sheet. The initial resistance is proportional to the amount of the residual adsorbed molecules on the graphene sheet. Thus, the resistance change is negatively proportional to the initial resistance.

論文審定書 i
摘要 ii
Abstract iii
目錄 iv
圖次 vi
第一章 簡介 1
1-1 前言 1
1-2 動機 2
第二章 基本理論 3
2-1 石墨烯(graphene)的基本特性 3
2-2 石墨烯的製程方法 4
2-2-1 膠帶剝離法 4
2-3-1 微機械剝離法 5
2-3-1 碳化矽熱裂解法 6
2-3-1 化學氣相沉積法 7
2-3 Polanyi-Wigner equation 8
2-4 石墨烯電阻變化之理論分析 9
第三章 儀器介紹 10
3-1 直流電源電錶 10
3-1-1 Keithley 2400 SourceMeter 10
3-2-2 四點量測 11
第四章 實驗結果與討論 12
4-1 實驗架構 12
4-2 石墨烯電阻變化與乙醇溶液濃度的關係 13
4-2-1 石墨烯浸泡乙醇溶液電阻隨時間變化關係 13
4-2-2 石墨烯電阻變化量與乙醇溶液濃度的關係 17
4-2-3 石墨烯表面乙醇溶液的揮發速率 18
4-3 不同起始電阻與電阻變化最大值的關係 22
4-3-1 不同起始電阻的石墨烯與電阻變化最大值的關係 22
4-3-2 石墨烯表面溶液殘留與電阻變化最大值的關係 23
第五章 結論 24
參考文獻 25

[1] A. K. Geim1 and K. S. Novoselov, “ The rise of graphene ”, Nature Materials 6, 183 - 191 (2007).
[2] K. S. Novoselov, A. K. Geim, D. Jiang, Y. Zhang, I. V. Grigorieva, “ Electric Field Effect in Atomically Thin Carbon Films ”, Science, 306, 666-669 (2004).
[3] Yuanbo Zhang, Joshua P. Small, William V. Pontius, and Philip Kim, “ Fabrication and electric-field-dependent transport measurements of mesoscopic graphite devices ”, Appl. Phys. Lett., 86, 073104 (2005).
[4] Claire Berger, Zhimin Song, Xuebin Li, Xiaosong Wu, Nate Brown, Tianbo Li, Joanna Hass, Alexei N. Marchenkov, Edward H. Conrad, Phillip N. First, Walt A. de Heer, “Electronic Confinement and Coherence in Patterned Epitaxial Graphene ”, Science, 312, 1191-1196 (2006).
[5] Xuesong Li, Weiwei Cai, Jinho An, Dongxing Yang, Richard Piner, Aruna Velamakanni, Inhwa Jung, Rodney S. Ruoff, “ Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper Foils “, Science, 324, 1312-1314 (2009).
[6] A. S. Bolina, A. J. Wolff and W. A. Brown, “Reflection absorption infrared spectroscopy and temperature programmed desorption investigations of the interaction of methanol with a graphite surface “, J. Chem. Phys. 122, 044713 (2005).
[7] Ganhua Lu, Sungjin Park, Kehan Yu, Rodney S. Ruoff, Leonidas E. Ocola, Daniel Rosenmann, and Junhong Chen, “Toward Practical Gas Sensing with Highly Reduced Graphene Oxide: A New Signal Processing Method To Circumvent Run-to-Run and Device-to-Device Variations “, ACS Nano, 5 (2), 1154–1164 (2011).
[8] KEITHLEY, Nanotechnology Measurement Handbook.
[9] Jeremy T. Robinson, F. Keith Perkins, Eric S. Snow, Zhongqing Wei and Paul E. Sheehan, “Reduced Graphene Oxide Molecular Sensors “, Nano Lett., 8 (10), 3137–3140 (2008).
[10] Yasuhide Ohno, Kenzo Maehashi, Yusuke Yamashiro and Kazuhiko Matsumoto, “Electrolyte-Gated Graphene Field-Effect Transistors for Detecting pH and Protein Adsorption “, Nano Lett., 9 (9), 3318–3322 (2009).
[11] Jing Kong, Nathan R. Franklin, Chongwu Zhou, Michael G. Chapline, Shu Peng, Kyeongjae Cho and Hongjie Dai, “Nanotube Molecular Wires as Chemical Sensors “, Science 287 622 (2000).
[12] Philip G. Collins, Keith Bradley, Masa Ishigami and A. Zettl, “Extreme Oxygen Sensitivity of Electronic Properties of Carbon Nanotubes “, Science 287 1801 (2000).
[13] F. Schedin, A. K. Geim, S. V. Morozov, E. W. Hill, P. Blake, M. I. Katsnelson and K. S. Novoselov, “Detection of individual gas molecules adsorbed on graphene “, Nat. Mater., 6 652 (2007).
[14] Stefano Prezioso, Francesco Perrozzi, Luca Giancaterini, Carlo Cantalini, Emanuele Treossi, Vincenzo Palermo, Michele Nardone, Sandro Santucci and Luca Ottaviano, “ Graphene Oxide as a Practical Solution to High Sensitivity Gas Sensing “, J. Phys. Chem. C 117 10683 (2013).
[15] Elsebeth Schröder, “Methanol Adsorption on Graphene”, Journal of Nanomaterials, vol. 2013, Article ID 871760, 6 pages, 2013