本篇論文成功的將二維材料石墨烯與氧化鋅和傳統矽基材料結合，藉由不同的材料排列方式，我們提出了三種類型的元件架構，分別是type1石墨烯/矽基板二極體、type2矽/石墨烯/矽基板電晶體、type3氧化鋅/石墨烯/矽基板電晶體。由於石墨烯具備高載子遷移率、可大面積生長的優異特性，讓它有潛力被應用在高速電子元件和光感測元件中。本篇論文將石墨烯整合於電晶體的基極端，單層至數層的石墨烯可以構成很薄的基極厚度，能減少載子在基極中複合的機率，並獲得更高的電流增益。石墨烯的特性類似金屬，因此即使基極很薄，我們也不需要擔心電晶體有擊穿(punch through)現象的發生，基於此概念，本論文期望能製作出一個具有高共射極電流增益(common-emitter current gain)的元件。
由Gummel Plot的量測圖型得知，本論文的電晶體在特定偏壓下，共射極電流增益最大可逼近42659，在同樣偏壓下量測到的共基極電流增益(common-base current gain)幾乎等於1，這是傳統半導體/金屬/半導體電晶體所無法匹敵的。而透過元件實際的電流圖，推導出的基極區傳輸因數(base transport factor)也穩定座落於0.93以上。此外本論文所設計的電晶體，皆不需外加太大的偏壓，即可獲得破千的增益值，且操作區間寬廣，而傳統的雙極性電晶體的電流增益才約莫300，且操作電壓往往需要在2V以上。另一方面我們還探討以石墨烯電晶體作為光感測用途時的表現，在光波長520nm，照光功率為100μW的情況下，本論文電晶體的電壓響應度最高可以達到6132 V/W、電流響應度最高為0.7652A/W。實驗室先前製作的異質接面電晶體[24]，在光波長520nm，照光功率100μW的情況下，電壓響應度為600 V/W。而現有的石墨烯二極體，在波長488nm，照光功率為1.23μW的情況下，電流響應度為0.225A/W[21]。綜合上述的結果，本論文所實現的石墨烯異質接面電晶體，和以往的文獻相較之下，不論是電流或是電壓響應都有不錯的提升。

We successfully combine two-dimensional material graphene with zinc oxide and conventional silicon materials in this thesis, and also demonstrate three types of electronic devices in different arrangement, which are graphene/silicon diode (I), silicon/graphene/silicon transistor (II), ZnO/graphene/silicon transistor (III).Graphene has potential to be applied in high-speed electronic devices and photo sensors due to its unique properties such as high mobility and large-area production. In this thesis, we planned to utilize graphene as the base material in transistor. Since the single-layer to several-layer graphene material can form a very thin base, which will contribute higher current gain because of lower recombination possibility during carrier diffusion in neutral base region. Furtherrmore, the characteristics of graphene are similar to metals, so even if the base is very thin, we still don’t need to worry about the punch through phenomenon. Based on those concepts, we dedicate to design a high common emitter current gain device.
According to the measurement of Gummel Plot, the common emitter current gain of the transistor can approximate to 42659 under a certain bias voltage. The common base current gain measured under the same bias voltage is also extremely close to 1 .The base transport factor derived from the actual current pattern of the device is also stable above 0.93. In addition, the transistor in this thesis can obtain the gain value higher than 1000 without applying high bias voltage and the devices operation range is wide enough. While the current gain of traditional transistor is only about 300, and often needs to be operated above 2V. In the meantime, we also studied the performance of graphene transistors as a photo sensor. Under the exposure of green light LED (λ=520nm, P=100μW), the maxiumum voltage responsivity of this device can achieve 6132V/W, and the current responsivity can reach 0.7652A/W. Undoubtedly, the graphene based transistor in our thesis has better performance in both voltage and current responsivity than heterojunction transistor (λ=520nm, P=100μW, voltage responsivity is 600 V/W[24]) or conventional graphene diode (λ=488nm, P=1.23μW, current responsivity is 0.225A/W[21]).

[1] Mermin N. D., “Crystalline order in two dimensions.”, Phys. Rev. 176, 250-254 (1968).
[2] Geim A. K., Novoselov K. S., “The rise of graphene.”, Nature Material 6, 183–191 (2007).
[3] K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, A. A. Firsov, “Electric Field Effect in Atomically Thin Carbon Films”, Science, vol. 306, Issue 5696, pp.666-669, 2004.
[4] K. I. Bolotin, et al., “Ultrahigh electron mobility in suspended graphene”, Solid State Communications, Vol. 146, Issue 9-10, pp.351-355, 2008.
[5] Alexander A. Balandin, “Thermal properties of graphene and nanostructured carbon materials”, Nature Mater. 10, 569–581, 2011.
[6] Schwierz, F, “Graphene transistors”, Nature Nanotechnol. 5, pp 487–496, 2010.
[7] Echtermeyer, T. J., Britnell, L., Jasnos, P. K., Lombardo, A., Gorbachev, R. V., Grigorenko, A. N., Geim, A. K., Ferrari, A. C., Novoselov, K. S., “Strong Plasmonic enhancement of photovoltage in graphene”, Nat. Commun., 2, 458, 2011.
[8] Maria Losurdo, Giovanni Bruno, “Graphene: potential ITO-replacement as transparent conductive layer”, National Council of Research(Italy).
Web site: http://amanac.eu/workshops/wsed2015/?b5-file=1974&b5-folder=1981
[9] Y. Wu, et al.,“High-frequency, scaled graphene transistors on diamond-like carbon”, Nature, vol. 472, no. 7341, pp. 74–78, 2011.
[10] V. D. Lecce, et al., “Graphene-Base Heterojunction Transistor: An Attractive Device for Terahertz Operation”, IEEE Transactions on Electron Devices, vol. 60, issue 12, pp.4263-4268, 2013.
[11] P. R. Wallace, “The band theory of graphite”, Phys. Rev., vol. 71, pp.622-634, 1947.
[12] D.S.L. Abergel, V. Apalkov, J. Berashevich, K. Ziegler, and Tapash Chakraborty, “Properties of graphene: a theoretical perspective”, Advances in Physics, vol. 59, No. 4, pp.261-482, 2010.
[13] Ying ying Wang, Zhen hua Ni, Ting Yu, Ze Xiang Shen, Hao min Wang, Yi
hong Wu, Wei Chen, et al., “Raman Studies of Monolayer Graphene: The Substrate Effect”, J. Phys. Chem., vol.112, No.29, pp.10637–10640, 2008.
[14] Zhen hua Ni, Ying ying Wang, Ting Yu, and Ze xiang Shen, “Raman spectroscopy and imaging of graphene”, Nanyang Technological University, Singapore 637371.
[15] S. M. Sze, “Semiconductor Device Physics and Technology”, John Wiley & Sons Inc., 3rd
[16] D. F. Swinehart, “The Beer-Lambert Law”, Journal of Chemical Education, pp.333, 1962.
[17] Donald A. Neamen, “Semiconductor Physics and Devices: Basic Principles, 4e”,Mc Graw Hill Education, 2013.
[18] K. S. Novoselov, V. I. Fal’ko, L. Colombo, P. R. Gellert, M. G. Schwab and K. Kim, “A roadmap for graphene”, Nature, 192, 490, 2012.
[19] Xuesong Li, Luigi Colombo and Rodney S. Ruoff, “Synthesis of Graphene Films on Copper Foils by Chemical Vapor Deposition”, Adv. Mater., 28, pp.6247-6252, 2016.
[20] Sreekar Bhaviripudi, Xiaoting Jia, Mildred S. Dresselhaus, and Jing Kong, “Role of Kinetic Factors in Chemical Vapor Deposition Synthesis of Uniform Large Area Graphene Using Copper Catalyst” , Nano Lett, 10, pp.4128-4133, 2010.
[21] Xiaohong An, Fangze Liu, Yung Joon Jung and Swastik Kar, “Tunable Graphene−Silicon Heterojunctions for Ultrasensitive Photodetection”, Nano Lett. 13, pp 909−916, 2013.
[22] Wet Chemical Etchants Standardized, Research gate, September 2014
[23] S. Vaziri, et al., “A graphene-based hot electron transistor”, Nano Lett,vol. 13, no. 4, pp. 1435–1439, 2013.
[24] 蘇秉國, “石墨烯異質接面電晶體特性研究”, 清華大學, 碩士論文, 2018
[25] S. M. Sze, C. R. Crowell, G. P. Carey, and E. E. LaBate, “Hot-Electron Transport in Semiconductor-Metal-Semiconductor Structures” Journal of Applied Physics 37, 2690 (1966);
[26] S. M. Sze and H. K. Gummel, Bell Telephone Laboratories, “Appraisal Of Semiconductor-Metal-Semiconductor Transistor ” Solid-State Electronics ,Pergamon Press 1966. Vol. 9, pp. 751-769.
[27] 郭俊佑, “應用多晶矽/石墨烯光二極體與MOSFET整合元件於影像感測陣列中”, 清華大學, 碩士論文, 2017
[28] 古慈安, “石墨烯於光感測元件之應用研究”, 清華大學, 碩士論文, 2014
[29] Neil P. Dasgupta, Sebastian Neubert, Wonyoung Lee, Orlando Trejo, Jung-Rok Lee and Fritz B. Prinz“Atomic Layer Deposition of Al-doped ZnO Films: Effect of Grain Orientation on Conductivity” Chem. Mater.2010, 22, 4769–4775 4769.