石墨烯，特殊的二維結構使其具有很多優異特性，非常有潛力應用為可撓曲透明導電膜，此類型石墨烯適合以化學氣相沉積法製備，但此法製備之石墨烯為多晶態(數個單晶組成)，產生晶界阻礙電子傳導，降低其導電性。常見的方法為堆疊多層或摻雜載子，皆能有效改善其導電性，但是皆有各自的缺點；本研究著重於控制石墨烯的單晶，以減少其晶界數量，降低單層石墨烯本身的片電阻。 本研究獨特的分析方法，利用ImageJ影像處理與分析軟體，對SEM所拍攝的圖片進行處理及統計，比較不同製程情況下的單晶密度、形貌和成長，加上拉曼光譜儀掃描的結晶性，及四點探針量測的片電阻，全方位探討製程中每個環節對石墨烯單晶之影響，以減少晶界的數量、提升成長的品質，製備導電性最佳的石墨烯。使用電化學拋光銅箔作為基板，調整氬氣、氫氣、甲烷流量分別為1000、30、0.5 sccm，在1070℃下以APCVD製備石墨烯，單層石墨烯的片電阻約310 Ω/□，波長350~1000 nm的平均穿透率約97.7 %，透過摻雜片電阻可達到約180 Ω/□，與其他文獻相比，本研究之石墨烯擁有較佳的透明導電特性，並足以應用為透明導電膜。 Graphene is a two-dimensional monolayer of sp2-bonded carbon atoms. In cases where synthesized by chemical vapor deposition (CVD), graphene is especially a promising candidate for the flexible transparent conductive films due to its flexibility, high optical transmittance and exceptional electrical conductivity. However, when graphene is deposited by CVD, it will be polycrystalline with grain (or domain) boundaries segregating grains, which means that graphene’s electrical properties would consequently be degraded. Both multilayer stacking and carrier doping have often been adopted to reduce the sheet resistance of the graphene films, but both have their own flaws. This study aims at increasing the grain size of the graphene films in order to reduce the quantity of grain boundaries, achieving a result of low sheet resistance of single-layer graphene. We have developed a unique method to analyze the grain density, the grain shape and the growth model of the graphene films at different processes: in order to investigate the grains of the graphene films comprehensively and find out a best procedure to fabricate graphene films with lowest sheet resistance, ImageJ, an image processing program, was utilized to analyze the grains of the grapheme films. Besides, the crystallized quality and the sheet resistance were surveyed respectively by Raman spectroscopy and four-point probe. Finally, the best procedure we have been able to find is: to grow the graphene films on electrochemical polishing Cu foils at 1070℃ with 1000 sccm Argon, 30 sccm Hydrogen and 0.5 sccm methane by ambient pressure CVD the resulting sheet resistance of the single-layer grapheme has reached 310 Ω/□ and the average transmittance is 97.7 % between 350-1000 nm wavelengths the sheet resistance has further reduced to 180 Ω/□ after doping process. It meets the industrial requirements of the transparent conductive films.
