【摘要】：石墨烯作為一種以sp2雜化的碳原子組成的單原子層二維材料,自2004年首次在實驗中被制備以來,受到了廣泛的關注和研究。石墨烯獨特的電學、熱學和光學等特性,使其在微電子、儲能、透明導電電極以及復合材料等領域有著廣闊的應用前景。石墨烯在許多領域的應用對其電子結(jié)構(gòu)、電導率以及透光率等性能有著嚴格的要求,而這些性能與石墨烯的層數(shù)緊密相關。因此,精確的控制石墨烯的層數(shù)成為十分重要的研究內(nèi)容。雖然現(xiàn)有報道提出了一些得到確定層數(shù)石墨烯的方法,快速可控得到精確層數(shù)石墨烯仍然是現(xiàn)階段石墨烯應用的一大瓶頸。同時,制備圖案化石墨烯也是石墨烯應用中亟需解決的問題。另外,石墨烯零帶隙半導體的特性導致了本征石墨烯難以直接應用到半導體器件中,所以石墨烯電學性能的調(diào)控成為了研究熱點之一。結(jié)合以上在石墨烯應用領域的研究熱點,本論文提出了一種通過激光輻照的方式對石墨烯進行精確的層數(shù)控制、圖案化和性能調(diào)控的新方法。由于具有加工過程簡單、非接觸式加工、環(huán)境友好、加工效率高以及加工過程柔性等優(yōu)勢,本方法在石墨烯電子器件領域有著廣闊的應用前景。采用連續(xù)CO2激光在真空環(huán)境下對石墨烯進行輻照,通過功率密度和輻照時間的調(diào)控,將原始多層石墨烯均勻減薄至2層。采用拉曼光譜、透射電子顯微鏡以及透過率等手段表征了實驗的結(jié)果。提出了一種采用皮秒激光精確減薄石墨烯的新方法。通過皮秒激光掃描的方法實現(xiàn)多層石墨烯的減薄。研究了激光能量密度和掃描速度對石墨烯減薄的影響,得出了將石墨烯減薄至不同層數(shù)的能量閾值。精確減薄的結(jié)果通過拉曼光譜、掃描電鏡、透過率等手段進行表征。根據(jù)超快激光與石墨烯的相互作用機制,提出了一種石墨烯減薄的剝離機理。本方法加工過程簡單,加工環(huán)境友好,加工速度快,單次加工即可得到所需層數(shù)的石墨烯,與現(xiàn)有方法相比具有很大的優(yōu)勢。通過圖案化的石墨烯減薄和切割實現(xiàn)了任意層數(shù)任意形狀石墨烯的制備。通過能量密度和掃描速度的調(diào)控,得出飛秒激光切割單層和多層石墨烯的能量閾值。與現(xiàn)有圖案化方法相比,具有非接觸式加工、加工效率高、柔性加工等優(yōu)點。采用低功率皮秒激光對石墨烯進行摻雜,通過拉曼光譜和XPS分析了摻雜效果和摻雜機理。并采用摻雜后的石墨烯搭建了單層石墨烯-硅太陽能電池,將其轉(zhuǎn)換效率提高至6.4%。
[Abstract]:Graphene, as a two-dimensional monatomic layer material composed of sp2 hybrid carbon atoms, has been widely studied since it was first prepared in the experiment in 2004. Because of its unique electrical, thermal and optical properties, graphene has a broad application prospect in the fields of microelectronics, energy storage, transparent conductive electrodes and composites. The applications of graphene in many fields have strict requirements for its electronic structure, conductivity and transmittance, which are closely related to the number of layers of graphene. Therefore, it is very important to control the layer number of graphene accurately. Although some methods for determining the layer number of graphene have been put forward in the present reports, rapid and controllable obtaining of accurate layer number of graphene is still a major bottleneck in the application of graphene at present. At the same time, the preparation of patterned graphene is an urgent problem in the application of graphene. In addition, because of the characteristics of graphene zero-band gap semiconductor, the intrinsic graphene is difficult to be directly used in semiconductor devices, so the regulation of graphene electrical properties has become one of the hot research topics. In this paper, a new method for controlling the number of layers, patterning and performance of graphene by laser irradiation is proposed. Due to the advantages of simple process, non-contact processing, environmental friendliness, high processing efficiency and flexible processing process, this method has a broad application prospect in the field of graphene electronic devices. Graphene was irradiated by continuous CO2 laser in vacuum environment. The original multilayer graphene was evenly thinned to 2 layers by the control of power density and irradiation time. The experimental results were characterized by Raman spectroscopy, transmission electron microscopy and transmittance. A new method for accurately thinning graphene by picosecond laser is proposed. The multilayer graphene is thinned by picosecond laser scanning. The effects of laser energy density and scanning speed on graphene thinning are studied and the energy threshold of reducing graphene to different layers is obtained. The exact thinning results were characterized by Raman spectroscopy, scanning electron microscopy and transmittance. According to the interaction mechanism between ultrafast laser and graphene, a mechanism of graphene thinning is proposed. The method is simple in processing, friendly in processing environment, fast in processing speed, and can obtain the required layers of graphene in a single process, which has a great advantage compared with the existing methods. The preparation of graphene with any number of layers and shapes was realized by thinning and cutting graphene with pattern. The energy threshold of femtosecond laser cutting monolayer and multilayer graphene was obtained by adjusting the energy density and scanning speed. Compared with the existing patterning methods, it has the advantages of non-contact machining, high processing efficiency and flexible machining. Graphene was doped by low power picosecond laser. The doping effect and doping mechanism were analyzed by Raman spectroscopy and XPS. A monolayer graphene silicon solar cell was built with doped graphene, and its conversion efficiency was improved to 6.4.
【學位授予單位】：清華大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ127.11

【參考文獻】

相關期刊論文 前3條

1 張蕓秋;梁勇明;周建新;;石墨烯摻雜的研究進展[J];化學學報;2014年03期

2 焦小亮;張悅煒;何潺;徐劍峰;楊靖霞;洪樟連;;石墨烯制備與帶隙調(diào)控的研究進展[J];材料導報;2012年05期

3 傅強;包信和;;石墨烯的化學研究進展[J];科學通報;2009年18期

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本文編號：2348756