以化學氣相沉積法製備石墨烯及其官能化

Abstract

石墨烯是以碳原子組成單層原子厚度的二維材料，具有良好的機械強度、化學穩定性、電子遷移率、高透光度等等的新穎材料，具有相當好的應用前景，例如薄膜場效電晶體(thin film field effect transistor)、薄膜透明電極(thin film transparent electrode)等等，故我們便開始著手研究石墨烯科學。 製備石墨烯的方法非常多種，本論文採用常見的化學氣相沉積法(Chmeical Vapor Deposition ,CVD)，以銅箔(Cu foil)作為金屬催化劑，使石墨烯薄膜成功穩定的成長在金屬基板上。為了將石墨烯轉印到適當之基材上，並能夠大量並快速準確地與太陽能電池、場效電晶體等光電元件製程相容，我們利用兩種方式：(一) PMMA法，以PMMA抓取石墨烯並以酸性溶液蝕刻基板，以人力轉印的技術使銅箔上的石墨烯能夠輕易地轉印到任何基板上。(二) 護貝機式熱脫膠，以膠膜黏取石墨烯，蝕刻後直接貼在基板上，通過護貝機熱滾軸完成脫膠。 最後為了光電在元件應用性的改進，希望能夠(一)進一步降低石墨烯的電阻值，(二)致力於製備LWF或HWF的石墨烯。我們分別使用兩種有機小分子，以化學摻雜法(chemical doping)成功的得到LWF與HWF的石墨烯，並偵測其石墨烯所對應的功函數4.277與4.799且獲得比原始石墨烯小超過50%的電阻值，希望能有更廣泛的應用。

Graphene, a novel material with 2D-planner which is composed of carbons with only one-atom-thick. The special properties of graphene included a high mechanical strength, good chemical stability, excellent electron mobility, and high transparency. Furthermore, graphene has already been shown promising applications, such as thin film effect transistors, thin film transparent electrodes...etc. So we start to investigate the science of graphene. There are many kinds of methods to prepare graphene, in this article, to grow graphene on metal substrate successfully and stably, we use the Chemical Vapor Deposition method and select to use Cu foil as the metal catalyst. Then for transfer graphene onto other substrate, we use two transfer methods, PMMA and roll to roll method. For PMMA method: CVD graphene was transferred by depositing PMMA on top of the graphene on substrates by spin coating, then underneath the graphene was dissolved by dipping the substrates in acidic solution, and then transferred onto substrate. Finally, the PMMA layer was dissolved with acetone , leaving the graphene film on the target substrate surface. For rollto roll method: We adhesion of a thin polymer supports to the graphene on the copper foil by passing between two rollers, then etched the copper foil by acidic solution. Finally, the graphene films are transferred from the polymer support onto substrate by removing the adhesive force holding the graphene films. Finally, to improve the application of opto-electronic devices. We try to decrease the resistance of graphene and devote preparation of low work function and high work function graphene and the resistance of graphene were decreased. So we use two small organic compound N-Fluorobenzenesulfonimide(NFSI) and 1-Nitropyrene(1-NP) respectively to get LWF and HWF graphene successfully by a simple chemical doping process respectively. The low and high work function graphene with the WF equal to4.277 , 4.799 were obtained respectively and the resistance were decreased successfully.