利用氣流梯度調控之高品質石墨烯成長

Abstract

隨著人類對生活品質的追求越來越高，電子產品的尺寸也急遽縮小，製作元件的材料體積也勢必需要大幅的調整。石墨烯是由碳之間以sp2鍵結的六碳環組成之二維平面材料，其優良的機械性質、電子特性，使研究學者們相當看好石墨烯的前瞻性，因此展開石墨烯的研究熱潮。取得石墨烯的方法有許多，而最一開始也最廣為人知的方法即是利用機械剝離法，然而其取得不易，且無法製造大面積之石墨烯，對於工業上的應用有限。化學氣相沉積法(CVD)便是近年來取得石墨烯的首選方法，其透過調控氣流及溫度，能夠在催化基板上成核並成長出大面積且連續的石墨烯，在經由適當的轉印方法後，我們便能將石墨烯置至基板。化學氣相沉積法不僅能夠大面積生產石墨烯，且能穩定地供應材料，這對於工業上的應用有非常大的實質幫助。 近期雙層及多層石墨烯發展了關於光電及電化學之的應用，而其他研究團隊討論到在CVD方法下，利用銅包成長雙層石墨烯之機制，激盪我們思考氣流梯度之運用。我們將銅包之氣流梯度觀念，運用在銅片之成長，銅片除了製作過程簡易之外，我們還能控制氣流之梯度，進而得到不同多層島嶼覆蓋率之石墨烯。並且在氣流梯度的影響下，我們僅需透過一次的銅箔成長，便得以在不同表面取得相異成長結果之石墨烯。最終我們透過實驗了解到利用氣流梯度控制石墨烯在銅片上的成長機制，而碳原子的滲透為一重要關鍵。在氣流與成長時間的準確調控下，我們能長出單片島狀石墨烯，對於單片原子層材料的局部分析十分有幫助。在電化學實驗中，我們發現石墨烯的出現能夠增強催化效果，而島狀單片石墨烯影響更盛，主要歸功於其邊界催化。我們把邊界催化之觀念運用在多層島狀石墨烯上，發現催化的效果優於無邊露出之石墨烯。經由以上觀念我們便能在大面積之連續石墨烯上進行催化的優化，在工業界勢必能有相當好的展望。

The life quality pursued by human is rising, and the size of electronic products needs to be rapidly minified, so the volume of materials applied in devices has to be adjusted substantially. Graphene, a two-dimensional hexagonal lattice structure composed of sp2-bonded carbon atoms, due to its outstanding mechanical and electrical properties, scientists expect the development of graphene. Among several approaches to fabricate graphene, chemical vapor deposition (CVD) is the most feasible method to synthesize high-quality graphene with large area. Moreover, CVD is a quite stable method to grow graphene, it is an essential help to apply graphene in industry. Other groups researched the mechanism of growing bilayer graphene on Cu pockets, and promote us use the concept of gas flow gradient in graphene growth. We apply gas flow gradient to grow graphene on Cu sheets without manufacturing in pocket-structure. Based on controlling gas flow gradient in the furnace, we can grow graphene with different coverage of multilayer islands. On the other hand, with precisely control gas flow and growth time, we can synthesize single atomic graphene sheet. In electrochemistry experiment, we observe the catalytic ability is enhanced in the presence of graphene, and the effect of graphene edges on graphene islands is more significant. Similarly, we learn the catalytic ability of graphene edges on multilayer graphene islands are better than graphene without edges. With these results, we can apply continuous graphene with edges between layers in industry in order to improve the performance of catalysis.