石墨烯起源於在2004年，英國曼徹斯特大學的A. K. Geim和K. S. Novoselov利用機械剝離法(mechanical exfoliation)成功地將單層石墨從高定向熱裂解石墨(highly orientated pyrolytic graphite, HOPG)塊材上給剝離下來，引起了全世界的研究熱潮。由於石墨烯擁有許多優異的特性，因此亦是下一世代二維材料的候選人之一。

在現今資訊爆炸的時代，通訊科技的發達是不可或缺的因素之一。它拉近了人與人之間的距離，讓人們可以在第一時間內收到相關情報與訊息，不管是在軍事、交通、民間等方面上，都可見到通訊電子產品無所不在。近年來，因著石墨烯的高載子遷移率(200,000 cm^2/V‧s)、高電流承載力(> 10^9 A/cm^2)、高飽和速度及載子濃度易受閘極調變等優異特性，已經有許多石墨烯相關的高頻應用文獻被發表出來。雖然目前於碳化矽(SiC)基板上的石墨烯元件擁有極佳的高頻特性，但是製程成本十分昂貴，在量產上有實質的困難。

本論文選用同樣為絕緣性的氧化鋁(Al2O3)及氮化鋁(AlN)基板應用在石墨烯高頻元件上，並搭配T型鋁閘極結構與Self-alignment技術，讓元件的ft可達到33.5 GHz(氧化鋁)和43 GHz(氮化鋁)；fmax可達到23 GHz(氧化鋁)和26 GHz(氮化鋁)。在通道長度為差不多的情況下，已經能媲美於做在碳化矽基板上的例子，成功地達到降低製程成本的目標，且亦在倍頻器上展現了其應用價值。本論文的閘極氧化層是藉由自然乾式氧化的方式所形成，除了可得到良好品質的閘極電容(950 ~ 1100 nF/cm^2)，亦讓整體的製程溫度可以低於200度，因此在後段製程(back-end-of line, BEOL)的應用上有很高的潛力。

Since A. K. Geim and K. S. Novoselov peeled off successfully one layer graphite from the highly orientated pyrolytic graphite (HOPG) by mechanical exfoliation in 2004, numerous novel researches about graphene, a isolated mono-atomic carbon layer constituted of two-dimentional honeycomb lattice building block, had be triggered off. Due to graphene's fantastic and excellent properties, it is one of the candidates which are the new star for electronics industry in the next generation.

Today, electronic communication products can be seen everywhere. It shorten the distance between people and is one of the essential factors to expedite scientific and technological progress. Due to a large carrier mobility and long-range ballistic transport, many high-frequency applications of graphene-based literatures were published. Although high-speed graphenetronic built on silicon carbide substrate (SiC) has excellent high-frequency characteristics, but the cost is very expensive and mass production is difficult.

We shows state-of-the-art of high-speed graphenetronics built on insulator substrates such as sapphire and aluminum nitride. With the T-shaped gate and self-alignment, high-speed graphenetronics have achieved recorded unity current gain cut-off frequency of 43 GHz and maximum oscillation frequency of 26 GHz realized with transferred graphene films on AlN substrate. The performance has able to compare favourably with the case on SiC substrates. We can get high quality gate oxide layer (950~1100 nF/cm^2) by naturally dry oxidation, and complete the entire fabrication flow below 200 degrees. Therefore, it engaged to paves a way for seamless heterogeneous three-dimensional (3D) system integration with graphene-last flow in Si fab technology, where graphene IC's back-end-of line (BEOL) can be co-integrated with stand Si CMOS.

論文摘要................................................... I
目錄..................................................... IX
第一章序論................................................. 1
1.1 半導體科技的演進. . . . . . . . . . . . . . . . . . . . 1
1.2 碳材料的起源與發展. . . . . . . . . . . . . . . . . . . . 3
1.2.1 零維度- 富勒烯(Fullerene - C60) . . . . . . . . . . . 3
1.2.2 一維度- 奈米碳管(Carbon nanotube, CNT) . . . . . . . . 4
1.2.3 二維度- 石墨烯(Graphene). . . . . . . . . . . . . . . 4
1.3 微波的介紹與石墨烯高頻元件應用. . . . . . . . . . . . . . . 6
1.3.1 低雜訊微波放大器(Low Noise Amplifier, LNA). . . . . . . 7
1.3.2 混波器(Mixer). . . . . . . . . . . . . . . . . . . . 7
1.3.3 倍頻器(Doubler). . . . . . . . . . . . . . . . . . . 7
1.4 論文結構. . . . . . . . . . . . . . . . . . . . . . . . 9
第二章石墨烯的物性與電性..................................... 11
2.1 石墨烯的基本物性. . . . . . . . . . . . . . . . . . . . 11
2.1.1 石墨烯晶體結構. . . . . . . . . . . . . . . . . . . . 11
2.1.2 石墨烯電子能帶. . . . . . . . . . . . . . . . . . . . 13
2.1.3 無質量狄拉克費米子. . . . . . . . . . . . . . . . . . 16
2.2 石墨烯的基本電性. . . . . . . . . . . . . . . . . . . . 17
2.2.1 最小導電率. . . . . . . . . . . . . . . . . . . . . 17
2.2.2 石墨烯的散射源. . . . . . . . . . . . . . . . . . . . 19
2.2.3 石墨烯場效電晶體. . . . . . . . . . . . . . . . . . . 22
第三章散射參數與元件模型分析................................. 25
3.1 雙埠網路. . . . . . . . . . . . . . . . . . . . . . . 25
3.1.1 雙埠網路參數. . . . . . . . . . . . . . . . . . . . . 25
3.1.2 傳輸線的概念. . . . . . . . . . . . . . . . . . . . . 26
3.1.3 散射參數矩陣. . . . . . . . . . . . . . . . . . . . . 30
3.2 高頻元件小訊號模型分析. . . . . . . . . . . . . . . . . . 33
3.2.1 解嵌入法(De-embedding). . . . . . . . . . . . . . . 33
3.2.2 小訊號模型建立. . . . . . . . . . . . . . . . . . . . 36
3.2.3 Y 參數分析. . . . . . . . . . . . . . . . . . . . . 37
3.2.4 本質參數萃取. . . . . . . . . . . . . . . . . . . . . 38
3.3 高頻元件特性分析. . . . . . . . . . . . . . . . . . . . 40
3.3.1 電流增益與最大有效功率增益. . . . . . . . . . . . . . . 40
3.3.2 高頻下的阻抗. . . . . . . . . . . . . . . . . . . . . 44
第四章元件製程與量測方法..................................... 47
4.1 基板製備與清潔. . . . . . . . . . . . . . . . . . . . . 48
4.1.1 機械研磨拋光(Mechanical Polishing). . . . . . . . . . 48
4.1.2 基板的清潔. . . . . . . . . . . . . . . . . . . . . 49
4.2 石墨烯轉移. . . . . . . . . . . . . . . . . . . . . . 49
4.3 T 型鋁閘極(Mushroom-Shaped Gate). . . . . . . . . . . 51
4.3.1 自然氧化閘極氧化層. . . . . . . . . . . . . . . . . . 51
4.3.2 閘極結構與自我對準沉積. . . . . . . . . . . . . . . . . 52
4.4 元件結構設計. . . . . . . . . . . . . . . . . . . . . . 53
4.5 系統儀器介紹. . . . . . . . . . . . . . . . . . . . . . 55
4.5.1 電子束微影(Electron Beam Lithography). . . . . . . . 55
4.5.2 反應式離子蝕刻(Reactive Ion Etching, RIE). . . . . . 57
4.5.3 熱金屬蒸鍍(Thermal Evaporation). . . . . . . . . . . 59
4.6 高頻量測系統. . . . . . . . . . . . . . . . . . . . . . 60
4.6.1 系統架設與量測方法. . . . . . . . . . . . . . . . . . 60
4.6.2 網路分析儀(Performance Network Analyzer, PNA). . . . 61
第五章量測結果與分析........................................ 63
5.1 鋁閘極特性分析. . . . . . . . . . . . . . . . . . . . . 63
5.1.1 鋁閘極電容量測. . . . . . . . . . . . . . . . . . . . 63
5.1.2 鋁閘極品質測試. . . . . . . . . . . . . . . . . . . . 65
5.2 元件在直流下的特性. . . . . . . . . . . . . . . . . . . 66
5.3 元件在高頻下的特性. . . . . . . . . . . . . . . . . . . 69
5.4 元件的量測結果分析. . . . . . . . . . . . . . . . . . . 72
5.5 元件在倍頻器的應用. . . . . . . . . . . . . . . . . . . 74
第六章結論與未來展望........................................ 75
參考文獻.................................................. 79

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