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標題: | 石墨烯於γ相氧化鋁基板成長之研究 Graphene Growth on γ Phase Alumina Oxide Substrate |
作者: | Chang-Chen Lo 羅張誠 |
指導教授: | 溫政彥 |
關鍵字: | 石墨烯,化學氣相沉積,γ-氧化鋁,乙炔,穿透式電子顯微鏡,X光繞射分析,拉曼分析光譜, graphene,chemical vapor deposition,γ-Al2O3,acetylene,Transmission Electron Microscopy (TEM),X-ray diffraction,Raman spectrum, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | 目前最常見且成本最低的高品質石墨烯製備方法為利用化學氣相沉積法將石墨烯成長於金屬基板,並且可以藉由參數的調控使得石墨烯的形貌以及層數達到均一性。成長於金屬基板的石墨烯必須將其轉印到其他介電基板後才可運用在元件製備上,因此有多種石墨烯轉印方法被發展出來,例如:熱脫膠轉印方法以及靜電轉印法等等。但這些轉印方法都會對石墨烯造成破壞,像是高分子的殘留、蝕刻液的摻雜或是轉印過程中的機械力的破壞,這些都會對石墨烯的品質造成影響。為了減少石墨烯元件製作過程中,對材料造成的破壞,我們嘗試將石墨烯直接成長於介電基板上。如此一來可以省去轉印的步驟,減少破壞,並且降低成本。本實驗利用乙炔當作碳源進行石墨烯成長,由於乙炔的高反應性使得可以在催化性不如金屬的氧化物基板上進行石墨烯成長。另外在基板選擇方面,我們使用γ-氧化鋁基板進行成長。相較於在藍寶石基板上以甲烷成長石墨烯所需1100℃以上的成長溫度,我們以乙炔作為碳源以及γ-氧化鋁當作成長基板,可在1000℃成長出石墨烯。而在低溫的情況下,雖然石墨烯無法生成,但是觀察到有乙炔裂解出的碳形成類似石墨烯的SP2結構,與在二氧化矽基板成長的結果對照下,說明γ-氧化鋁基板有較佳的催化性質。研究中,γ-氧化鋁基板是以原子層沉積方法於矽基板氧化層上沉積非晶相氧化鋁薄膜,再經由高溫退火形成γ-氧化鋁。我們利用穿透式電子顯微鏡(TEM)以及X光繞射分析研究氧化鋁基板的形成與結構,並用拉曼光譜分析石墨烯的品質。結果顯示γ-氧化鋁的結晶性、氣象反應物組成以及成長溫度均會影響石墨烯成長。 The most routine and low-cost approach to produce large-area graphene with a high quality is via the chemical vapor deposition (CVD) method on transition metal substrates. Uniform morphology and sheet numbers can easily be obtained for CVD-grown graphene films. For practical applications, these as-grown graphene films need to be transferred to other substrates for the subsequent fabrication of electronic devices. The transferring methods, such as the roll-to-roll method and the electrostatic lifting method, inevitably introduce defects, e.g. polymer residue or cracks, on graphene films, drastically degrading the transport properties of graphene. We therefore attempt to synthesize graphene directly on dielectric substrates, so that no further transferring steps are required before fabricating graphene devices. In this study, acetylene is used as carbon precursors in the CVD growth for lowering the growth temperature and making the growth process compatible with the semiconductor fabrication processes. Alumina oxide is a good dielectric material and the dielectric constant is larger than SiO2 so that it is useful for decreasing the size of device. In addition, the recent research found that sapphire can catalyze graphene growth at more than 1100℃ with methane. In order to decrease the growth temperature, we try to change the carbon source and the phase of Al2O3 in our experiment. In this study, acetylene is used as carbon precursors in the CVD growth for lowering the growth temperature to make the growth compatible with the semiconductor fabrication processes. We found that γ-Al2O3 can catalyze graphene growth without hydrogen with the use of acetylene as the carbon source. In addition, we found that the properties of γ-Al2O3, including thickness and the degree of crystallinity will also influence the graphene growth. We use the transmission electron microscopy (TEM) technique to characterize the morphology and interfacial properties of the graphene layers grown on the dielectric substrates. Raman spectroscopy and electrical measurements are used to certify their quality. However, under the low temperature condition, the carbon precursors are only decomposed and adsorbed on the surface of γ-Al2O3, without forming graphene layers. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/52771 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
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