近幾年石墨烯由於其特殊的電子特性而變得相當熱門，甚至被期望取代矽而成為最新的電子元件材料。然而，相對於P型石墨烯電晶體，一個室溫下穩定的N型石墨烯電晶體是非常難製作的。根據文獻顯示，當石墨烯在低氧化鈦上時被證實為具有高載子遷移率且擁有穩定的N型電子行為。為了研究低氧化鈦對石墨烯的效應，本論文利用掃描穿隧顯微鏡與掃描穿隧能譜量測石墨烯在低氧化鈦上的電子特性。實驗結果顯示，石墨烯不同層間的高度差，隨著石墨烯的層數增加，量測獲得之高度差越接近實際石墨烯高度差。掃描穿隧能譜顯示，石墨烯迪拉克點的能量位置低於費米能階，表現出N型電子特徵。這特殊的摻雜行為被歸因於石墨烯與低氧化鈦之間有很強的電荷轉移現象。在本工作中，利用掃描穿隧顯微鏡與掃描穿隧能譜探討不同層數之石墨烯的電性特徵，並量化摻雜能級、能態密度與電荷載子密度。

In recent years, graphene has been one of the popular materials due to its high mobility. Therefore, it is a potential candidate to replace Si as the base material of electronic components. However, compared to p-type graphene transistors, a stable n-type graphene transistor at room temperature is difficult to fabricate. Base on the previous study, graphene has demonstrated higher mobility and steadier n-type property on a titanium suboxide (TiOx) thin film. In order to investigate the effect of the TiOx substrate on graphene, the local electronic properties of the graphene/TiOx were measured by scanning tunneling microscopy and spectroscopy at a nano-scale level. The results show that the height of graphene layers approaches to a real height when the number of graphene layers becomes increasing. The energetic position of the Dirac point is located below the Fermi level, revealing the N-type electronic characteristic. Furthermore, the reason for such a unique doping behavior is attributed to the strong charge transfer between graphene and TiOx. In this work, the doping level, density of state and charge carrier density are quantized as a function of graphene layers.

摘要 i
Abstract ii
致謝 iii
目錄 iv
圖目錄 vi
表目錄 viii
第一章 緒論 1
1-1 石墨烯之結構 1
1-2 石墨烯之製備法 3
1-2-1 膠帶剝離法 3
1-2-2 化學氣相沉積法 3
1-2-3 碳化矽熱裂解法 3
1-2-4 氧化還原法 4
1-3 石墨烯之應用 5
第二章 研究動機 7
第三章 實驗儀器與原理 8
3-1 掃描穿隧顯微鏡(Scanning tunneling microscopy, STM) 8
3-2 量子穿隧效應(Quantum tunneling effect) 10
3-3 掃描穿隧能譜(Scanning tunneling spectroscopy, STS) 12
3-4 掃描模式 14
3-4-1 定電流模式 14
3-4-2 定高度模式 15
3-4-3 電流影像穿隧能譜(Current image tunneling spectroscopy, CITS) 15
3-5 掃描探針製備 17
3-6 超高真空系統 19
3-6-1 真空計 19
3-6-2 真空幫浦 20
第四章 實驗結果與討論 23
4-1 樣品資訊 23
4-2 石墨烯之形貌分析 24
4-3 低氧化鈦對石墨烯之影響 26
4-3-1 不同石墨烯層與能態密度之理論分析與討論 28
4-3-2 掃描穿隧能譜的迪拉克點(Dirac point)位置之理論計算 32
4-3-3 不同石墨烯層的電性之探討 34
4-3-4 不同石墨烯層的能態密度與摻雜能級(Doping level)之分析與討論 36
4-3-5 不同石墨烯層的電荷載子密度之分析 38
第五章 結論 39
參考文獻 40

[1] A.K. Geim, K.S. Novoselov, Nat. Mater., 6 (2007) 183-191.
[2] 李明洋, 唐九君, 物理雙月刊, 33卷 (2011) 208-213.
[3] C.W.J. Beenakker, Rev. Mod. Phys., 80 (2008) 1337-1354.
[4] K.S. Novoselov, A.K. Geim, S.V. Morozov, D. Jiang, Y. Zhang, S.V. Dubonos, I.V. Grigorieva, A.A. Firsov, Science, 306 (2004) 666-669.
[5] J. Vaari, J. Lahtinen, P. Hautojarvi, Catal. Lett., 44 (1997) 43-49.
[6] D.E. Starr, E.M. Pazhetnov, A.I. Stadnichenko, A.I. Boronin, S.K. Shaikhutdinov, Surf. Sci., 600 (2006) 2688-2695.
[7] N.R. Gall, E.V. Rut'kov, A.Y. Tontegode, Phys. Solid State, 46 (2004) 371-377.
[8] A.L.V. de Parga, F. Calleja, B. Borca, M.C.G. Passeggi, J.J. Hinarejos, F. Guinea, R. Miranda, Phys. Rev. Lett., 100 (2008) 056807.
[9] Y. Gamo, A. Nagashima, M. Wakabayashi, M. Terai, C. Oshima, Surf. Sci., 374 (1997) 61-64.
[10] C. Berger, Z.M. Song, T.B. Li, X.B. Li, A.Y. Ogbazghi, R. Feng, Z.T. Dai, A.N. Marchenkov, E.H. Conrad, P.N. First, W.A. de Heer, J. Phys. Chem. B, 108 (2004) 19912-19916.
[11] S. Stankovich, D.A. Dikin, G.H.B. Dommett, K.M. Kohlhaas, E.J. Zimney, E.A. Stach, R.D. Piner, S.T. Nguyen, R.S. Ruoff, Nature, 442 (2006) 282-286.
[12] J.H. Chen, C. Jang, S.D. Xiao, M. Ishigami, M.S. Fuhrer, Nat. Nanotechnol., 3 (2008) 206-209.
[13] Y. Kobayashi, K. Fukui, T. Enoki, K. Kusakabe, Y. Kaburagi, Phys. Rev. B, 71 (2005) 193406.
[14] T. Enoki, Y. Kobayashi, K.I. Fukui, Int. Rev. Phys. Chem., 26 (2007) 609-645.
[15] D.E. Jiang, B.G. Sumpter, S. Dai, J. Chem. Phys., 126 (2007) 134701.
[16] V. Barone, O. Hod, G.E. Scuseria, Nano Lett., 6 (2006) 2748-2754.
[17] M.Y. Han, B. Ozyilmaz, Y.B. Zhang, P. Kim, Phys. Rev. Lett., 98 (2007) 206805.
[18] P.L. McEuen, Phys. World, 13 (2000) 31-36.
[19] D.C. Wei, Y.Q. Liu, Y. Wang, H.L. Zhang, L.P. Huang, G. Yu, Nano Lett., 9 (2009) 1752-1758.
[20] L.Y. Zhao, M. Levendorf, S. Goncher, T. Schiros, L. Palova, A. Zabet-Khosousi, K.T. Rim, C. Gutierrez, D. Nordlund, C. Jaye, M. Hybertsen, D. Reichman, G.W. Flynn, J. Park, A.N. Pasupathy, Nano Lett., 13 (2013) 4659-4665.
[21] Y.Y. Shao, S. Zhang, M.H. Engelhard, G.S. Li, G.C. Shao, Y. Wang, J. Liu, I.A. Aksay, Y.H. Lin, J. Mater. Chem., 20 (2010) 7491-7496.
[22] Y.B. Zhang, V.W. Brar, F. Wang, C. Girit, Y. Yayon, M. Panlasigui, A. Zettl, M.F. Crommie, Nat. Phys., 4 (2008) 627-630.
[23] P.H. Ho, Y.C. Yeh, D.Y. Wang, S.S. Li, H.A. Chen, Y.H. Chung, C.C. Lin, W.H. Wang, C.W. Chen, ACS Nano, 6 (2012) 6215-6221.
[24] C. Julian Chen, Introduction to Scanning Tunneling Microscopy, (1993).
[25] D.A. Bonnell, Scanning Tunneling Microscopy and Spectroscopy Theory, Techniques, and Applications, (1993).
[26] X.F. Feng, M. Salmeron, Appl. Phys. Lett., 102 (2013) 053116.
[27] A. Luican, G.H. Li, E.Y. Andrei, Phys. Rev. B, 83 (2011) 041405.
[28] M.S. Chen, D.W. Goodman, Chem. Soc. Rev., 37 (2008) 1860-1870.
[29] J.N. Fuchs, M.O. Goerbig, Introduction to the Physical Properties of Graphene, (2008).
[30] E. Stolyarova, K.T. Rim, S.M. Ryu, J. Maultzsch, P. Kim, L.E. Brus, T.F. Heinz, M.S. Hybertsen, G.W. Flynn, Proc. Natl. Acad. Sci. U. S. A., 104 (2007) 9209-9212.
[31] S.J. Goncher, L.Y. Zhao, A.N. Pasupathy, G.W. Flynn, Nano Lett., 13 (2013) 1386-1392.
[32] R. Lv, Q. Li, A.R. Botello-Mendez, T. Hayashi, B. Wang, A. Berkdemir, Q.Z. Hao, A.L. Elias, R. Cruz-Silva, H.R. Gutierrez, Y.A. Kim, H. Muramatsu, J. Zhu, M. Endo, H. Terrones, J.C. Charlier, M.H. Pan, M. Terrones, Sci Rep, 2 (2012) 586.
[33] J. Choi, H. Lee, S. Kim, J. Phys. Chem. C, 114 (2010) 13344-13348.
[34] A.H. Castro Neto, F. Guinea, N.M.R. Peres, K.S. Novoselov, A.K. Geim, Rev. Mod. Phys., 81 (2009) 109-162.
[35] M.M. Ugeda, I. Brihuega, F. Hiebel, P. Mallet, J.Y. Veuillen, J.M. Gomez-Rodriguez, F. Yndurain, Phys. Rev. B, 85 (2012) 121402.
[36] A. Deshpande, W. Bao, F. Miao, C.N. Lau, B.J. LeRoy, Phys. Rev. B, 79 (2009) 205411.
[37] L.Y. Zhao, R. He, K.T. Rim, T. Schiros, K.S. Kim, H. Zhou, C. Gutierrez, S.P. Chockalingam, C.J. Arguello, L. Palova, D. Nordlund, M.S. Hybertsen, D.R. Reichman, T.F. Heinz, P. Kim, A. Pinczuk, G.W. Flynn, A.N. Pasupathy, Science, 333 (2011) 999-1003.