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標題: | 利用低損傷氧電漿摻雜於單層與雙層石墨烯電晶體進行傳輸特性之調變 Using Low-Damage-Oxygen-Plasma Modulate Transport Characteristics of Monolayer and Bilayer Graphene Transistor |
作者: | Win-Wai Tam 譚詠韋 |
指導教授: | 林致廷(Chih-Ting Lin) |
關鍵字: | 石墨烯電晶體,低損傷電漿,氧摻雜,能隙,單極性傳輸, graphene transistor,low damage plasma,oxygen-plasma treated,bandgap,unipolar transport, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 石墨烯(graphene)因具備極高的載子遷移率,所以十分具有潛力替代矽材料做為下一個世代的電晶體的通道材料。然而,石墨烯是一种類金屬(semimetal),它不具有能隙(bandgap),因此以它作為通道的電晶體元件通常都具有較小的電流開關比值(on-off ratio),加上它雙極性(ambipolar)的傳輸特性,將會造成電晶體在關閉狀態時,發生漏電的機率提高。
本論文將以化學氣相沉積法成長大面積的石墨烯於銅箔上,再利用氣泡掀離法把石墨烯轉印到目標基板上,接着使用低損傷氧電漿對單層石墨烯進行摻雜,使其產生能隙,提升電流開關比值,但是同時也會造成單層石墨烯的載子遷移率受到嚴重的鈍化(degradation)。因此接着改為對隨機堆疊的雙層石墨烯(random stacked bilayer graphene)進行重摻雜,雖然並未能觀察到能隙被打開的現象,可是卻發現石墨烯電晶體的傳輸特性從原本的雙極性變成了單極性(unipolar),轉化成p型石墨烯電晶體,推測是因為與金屬電極接觸的石墨烯和通道上的石墨烯之間形成了一p-n接面所導致,因此我們透過開爾文探針力顯微鏡對金屬電極與石墨烯的表面電位進行探討。 此外,本實驗也對摻雜前後的單層與雙層石墨烯進行拉曼光譜的分析,同時也藉由X射線光電子光譜儀來分析摻雜時間與石墨烯表面的碳氧比例的關係。 Graphene is a very promising candidate to replace silicon as a channel material for the next generation of transistor due to its extremely high carrier mobility. However, graphene is a kind of semimetal, which does not have a bandgap, so its transistor behavior shows poor on/off ratio. Besides, the ambipolar transport behavior of graphene make its leakage against the threshold voltage variation when the transistor operating in off state. In this paper, a large area of graphene is grown on copper foil by chemical vapor deposition and transferred onto the target substrate by using bubble process. After that, using low damage oxygen plasma doped monolayer graphene to open up its bandgap, improve the on/off ratio of the graphene transistor, but at the same time will causes the mobility of graphene being degraded. Therefore, we change to heavy doped random stacked bilayer graphene, although the bandgap was not being observed, but the transport characteristics of the bilayer graphene were changed from the original ambipolar to unipolar, converted into p-type transistor, we postulate is because the p-n junction are formed between the contacts region and graphene channel. Therefore, we use the Kelvin probe force microscope to analyze the potential difference between the contact and graphene. In addition, this experiment also analyzes the Raman spectrum of monolayer and bilayer graphene before and after doping, we also study the relation between the doping time and the ratio of carbon to oxygen on the surface of graphene by using X-ray photoelectron spectroscopy. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/73502 |
DOI: | 10.6342/NTU201900643 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
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