臺灣博碩士論文加值系統

近年來，石墨烯因其特有的性質以及在元件應用上的潛力而被廣為研究。在製作石墨烯的方法中，特別是磊晶生長法引起學界極大的興趣，因為利用此方法製作的石墨烯可以是晶圓級尺寸，並且石墨烯可以直接生長在碳化矽基板上而省去了轉移步驟。有關於石墨烯的眾多研究中，其中一個重要的議題即是探討石墨烯在低溫下的載子傳輸特性，因此，本篇論文著重於石墨烯樣品的傳輸性質分析，我們製作了單層的碳化矽磊晶石墨烯，並在低溫下進行了一系列的載子傳輸實驗。接著，透過resistance curve derivative analysis (RCDA) 方法進行分析，我們發現樣品的載子傳輸機制是由變程跳躍模型主導的。此外，我們研究不同磁場以及低溫真空退火後對樣品傳輸性質的影響，分析結果顯示，隨著磁場強度增加或者是進行低溫真空退火後，符合載子傳輸的模型會由Efros-Shklovskii (E-S) 變程跳躍模型轉變為Mott變程跳躍模型。我們的實驗結果顯示，單層碳化矽磊晶石墨烯是深入研究變程跳躍機制的一個很好的材料。

Graphene has been extensively studied due to its extraordinary properties and potentials for device applications in recent years. Among the methods of producing graphene, epitaxial growth method has gained a great deal of interest since epitaxial graphene on silicon carbide (SiC) substrate can be wafer-scale and the transfer process is not required. Nowadays, one of the important issues regarding graphene is to understand the nature of transport properties at low temperatures. In this thesis, we focus on the analysis of transport properties on the graphene sample. We fabricated monolayer epitaxial graphene on a SiC substrate, and a series of the transport measurements was made on the sample. By using the resistance curve derivative analysis method, we found that the transport of our sample can be well fitted by the variable range hopping (VRH) models. Besides, we also observed a crossover from Efros-Shklovskii (E-S) VRH to Mott VRH by increasing the applied magnetic field as well as by a gentle heating process. Our new experimental results suggest that monolayer graphene on SiC is an interesting platform for probing VRH conduction.

口試委員審定書 Ⅰ
致謝 Ⅱ
摘要 Ⅲ
Abstract Ⅳ
Contents Ⅴ
List of figures Ⅶ

Chapter 1 Introduction 1
References. . . . . . . . . . . . . . . . . . . . . . . . 4

Chapter 2 Background knowledge 6
2.1 Introduction to graphene . . . . . . . . . . . . . . 6
2.2 Epitaxial graphene growth on SiC . . . . . . . . . . 9
2.3 Quantum Hall effect . . . . . . . . . . . . . . . . 11
2.4 Variable range hopping (VRH) conduction . . . . . . 17
References . . . . . . . . . . . . . . . . . . . . . . . 22

Chapter 3 Sample fabrication and experimental techniques 23
3.1 Fabrication of epitaxial graphene sample . . . . . . 23
3.2 Transport measurement . . . . . . . . . . . . . . . 25
References. . . . . . . . . . . . . . . . . . . . . . . 29

Chapter 4 Experimental results of epitaxial graphene on SiC 30
4.1 Electrical properties of sample . . . . . . . . . . 30
4.2 VRH model for sample . . . . . . . . . . . . . . . . 35
4.3 Discussion . . . . . . . . . . . . . . . . . . . . . 40
References. . . . . . . . . . . . . . . . . . . . . . . 42

Chapter 5 Conclusion 43

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