石墨烯擁有卓越的電性，在各種電子應用中成為有前途的材料。為了能夠大規模合成石墨烯，化學氣相沉積被視為最有效率的生產方式，但不可避免地產生多晶石墨烯並包含晶界。晶界被認為會降低電傳輸。然而，很少有系統的實驗來仔細探索晶界數量對石墨烯電學性能的影響。 本實驗利用化學氣相沉積方法生長單層多晶石墨烯，在不同的生長溫度（760 °C - 1000 °C）下產生的多晶石墨烯中的晶界數量可以通過使用後處理在實驗上可視化晶界來計算。通過拉曼光譜觀察多晶石墨烯晶格中的缺陷。利用微影製程、乾蝕刻及蒸鍍系統製作了Van der Pauw的幾何形狀，並進行Van der Pauw和電化學阻抗頻譜的電性量測。結果表明，多晶石墨烯的薄層電阻和遷移率與晶界數量有關，晶界數量的增加會阻礙電子在石墨烯中的運動，當晶界達到臨界數量，晶界的影響會變得很微小。而進一步通過穿透電子顯微鏡觀察和計算分形維度，發現晶界的不同型態也會影響電荷的累積，良好域間連通性的晶界對電性是有利的。;Graphene possesses excellent electrical properties and has become a promising material in various electronic applications. Chemical vapor deposition is considered the most efficient production method for large-scale graphene synthesis. However, it inevitably results in polycrystalline graphene with grain boundaries. Grain boundaries are believed to reduce electrical conductivity. Nevertheless, there have been few systematic experiments to carefully explore the impact of grain boundary quantity on the electrical performance of graphene. In the experiment, monolayer polycrystalline graphene is grown using the chemical vapor deposition method. The quantity of grain boundaries in the polycrystalline graphene produced at different growth temperatures (760 °C - 1000 °C) was calculated by visualizing the grain boundaries using post-processing techniques. Defects in the graphene lattice were observed through Raman spectroscopy. Van der Pauw′s geometry was fabricated using photolithography, dry etching, and evaporation systems, enabling electrical measurements via Van der Pauw and electrochemical impedance spectroscopy. The results indicate that the sheet resistance and mobility of polycrystalline graphene are correlated with the quantity of grain boundaries. An increase in grain boundary quantity impedes electron motion in graphene, but their impact becomes minimal when the grain boundaries reach a critical quantity. Furthermore, by observing and calculating the fractal dimension through transmission electron microscopy, it was discovered that different types of grain boundaries also affect charge accumulation, with well-connected grain boundaries benefiting electrical properties.
