目前，合成大面积石墨烯的最常用方法是使用化學氣像沉積(CVD)。然而，以熱催化作為主要機制的CVD在生長的過程中通常需要高温(约1000℃)以及具有催化性質的基板幫助，這使得石墨烯薄膜的大規模生產及工業化有所限制。因此，通過電漿增強化學氣像沉積(PECVD)進行低温合成似乎是克服傳統熱催化CVD限制的解决方案。而在PECVD系统中，甲烷(CH4)因其穩定性通常被作為碳源添加於電漿中以成長石墨烯薄膜。然而較高的裂解能量限制了石墨烯在低基板温度下生長的可能性。因此，在此研究中，我們嘗試通過使用遠程微波電漿源来提高解離率並將碳源从甲烷改為乙炔來產生更多的C2自由基用來幫助石墨烯薄膜在PECVD中的生長。電漿解離所發出的發射光譜和PECVD生長石墨烯的拉曼光譜表明，遠程微波電漿能够為石墨烯生長提供足够的碳自由基，並且石墨烯的品質很大程度的取决于電漿中CH/C2的比例。並且在我们將遠程微波電漿與射頻電漿耦合後，射頻系統仍將主導生長，並限制了石墨烯生長品質。;For now, the most common way to synthesis large-area graphene is thermal chemical vapor deposition (CVD). However, thermal CVD typically need a high temperature around 1000℃ during the growth, which restricts mass production of graphene film and reduction of production cost. Therefore, the low temperature synthesis by plasma enhanced chemical vapor deposition (PECVD) seem to be a solution to overcome the limitation of thermal CVD. Generally, the methane plasma is used in the PECVD system for its stability. Meanwhile, the higher pyrolysis energy restricts the probability to grow graphene with low substrate temperature. Therefore, in this research, we try to improve the PECVD system by using remote Microwave plasma source to increase the ionization rate or changing the precursor from methane to acetylene to produce more C2 radicals. The optical emission spectrum of plasma and Raman spectrum of PECVD growth graphene shown that the remote MW plasma can provide sufficient carbon radicals for graphene growth and the quality of graphene is highly depending with the ratio of CH/C2 in the plasma source. Then, we find that the direct RF system will still dominate the growth after we coupled it with remote MW plasma, limited the quality of graphene.
