堆疊多層石墨烯之光電特性;The optical and electrical properties of multilayer graphene

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/54266

Title:	堆疊多層石墨烯之光電特性;The optical and electrical properties of multilayer graphene
Authors:	錢遠鴻;Chien,Yuan-hung
Contributors:	物理研究所
Keywords:	堆疊;石墨烯;多層;Graphene;multilayer;stacked
Date:	2012-07-31
Issue Date:	2012-09-11 18:41:10 (UTC+8)
Publisher:	國立中央大學
Abstract:	在本論文中，我們利用化學氣相沈積法成長高品質的單層石墨烯薄膜，並重覆轉印單層石墨烯以製成多層石墨烯薄膜，期望可以解決在一次成長多層石墨烯薄膜時，因層與層之間之相互作用所造成之光特性損失。並利用重複轉印的方式改善石墨烯薄膜的電特性。製程上，我們使用化學汽相沈積法在銅箔上成長單層石墨烯，並利用光阻(PMMA)和濕蝕刻方法將石墨烯薄膜轉印到二氧化矽基板上。經過拉曼光譜（Raman Spectrum）量測，顯示G band和2D band的半高寬皆小於40cm-1，並且2D/G的訊號強度比值大於1.5。這顯示我們以CVD方法成長於銅箔上為單層的石墨烯薄膜，且經過濕蝕刻轉印後，單層石墨烯薄膜的結構保持完整。經由霍爾量測，轉印後之石墨烯薄膜的平均片電阻約為2000 ohm/sq，並且大多數的樣品片電阻均分布在2000 ohm/sq附近，這顯示樣品之成長以及轉印過程的穩定性。在結構特性上，我們利用Raman Spectrum量測，顯示出直接成長之單層以及經過重複轉印之三層和五層的石墨烯薄膜之G band和2D band峰值並沒有相對位移，且半高寬及2D/G訊號強度的比值相似。2D band之訊號曲線保持左右對稱。這顯示層跟層之間並不存在交互作用力。在光性方面，重複轉印的多層石墨烯薄膜，在波長555nm處對光的吸收率約為3.1 %/層，在三層的情況下依然保持約90%的光穿透率。在電性方面，當層數低於三層時，石墨烯薄膜之片電阻降為單層片電阻的50%。當層數大於三層時，多層石墨烯薄膜之片電將接近高定向石墨（highly-oriented pyrolytic graphite, HOPG）的片電阻。在此論文中，我們成功利用重覆轉印的方式製成確定層數的多層石墨烯。且將片電阻降低的同時維持光穿透性在90％以上。並得到光電特性的最佳化結果。In this thesis, high quality monolayer graphene were grown on Cu foil by chemical vapor deposition, and we manufacture multilayer graphene by stacking monolayer graphene. The propose of stacking multilayer graphene is to obtain optimum condition both in optical and electrical properties. According to the results of Raman spectrum measurement, the full width at half maximum of G band and 2D band peaks are both smaller than 40 cm-1 and the ratio of 2D/G is larger than 1.5, which means the transferred graphene is monolayer. The average sheet resistivity of transferred graphene, which is measured by Hall measurement system, are about 2000 ohm/sq. For the optical and electrical properties of stacked multilayer graphene, the transmittance, Raman spectrum, and Hall measurement were taken. The Raman spectrum results shows that the peak positions of G and 2D band didn’t shift and the 2D/G ratio were almost the same between one and stacked multilayer graphene. In addition, no shoulders were observed in the 2D peak of Raman spectrum that means there should be no interactions between layers. In the optical transmittance results, the absorption of multilayer graphene is about 3.1%/layer at 555 nm wavelength. The transmittance of three layers graphene is about 90%. In electrical properties, the sheet resistivity of graphene were decreased to 50% and 75% with stacked layer number was two and three layers, respectively. When the layer number was increased more than five layers, the sheet resistivity of multilayer graphene was close to HOPG. In the thesis, we successfully manufacture certain layers graphene by stacking monolayer graphene. The sheet resistivity of stacked graphene was decreased and the optical transmittance of stacked graphene was above 90%.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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