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標題: | 透過雙重物理作用力實現無化學殘留之石墨烯轉印法研究 Residue-Free and Etching-Free Clean Graphene Transfer Method by Double Physical Forces |
作者: | Chien-Hsun Chuang 莊建勛 |
指導教授: | 陳俊維(Chun-Wei Chen) |
關鍵字: | 石墨烯,化學氣相沉積,轉印,蝕刻,化學殘留,物理力, graphene,chemical vapor deposition,transfer,residue,etching,physical force, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | 石墨烯是由單層碳原子以〖sp〗^2鍵結形成的新穎二維材料,因為其優越的化學、機械、電子特性,自2004年Novoselov團隊成功利用膠帶剝離法取得單層石墨烯後,此材料在學術界獲得極大的關注,關於石墨烯的研究也如同雨後春筍般展開。近年來因應產業應用的需求,如何製造大面積、高品質石墨烯成為一項極其重要的議題,其中化學氣相沉積法被視為最具有前景的製造方法之一。然而,在此製程中包含了一個相當關鍵的步驟-轉印;由於石墨烯透過化學氣相沉積法被合成於金屬基材表面,因此尚需透過轉印技術將石墨烯與金屬基材分離並移至矽晶片基板。一般而言,傳統轉印作法首先在石墨烯表面塗佈一層高分子保護膜,並利用化學蝕刻液將金屬基材去除,最後將此高分子/石墨烯薄膜轉至矽基板後再移除高分子層。在此一連串的化學步驟後,石墨烯將無可避免地受到諸多汙染,且高分子及蝕刻液的殘留也無法保證完全去除。為了改善此製程,我們期望能開發出一項創新的石墨烯轉印技術,其步驟內不包含任何化學處理。 本論文第一部分(第四章),我們介紹關於化學氣相沉積法製備的石墨烯之合成參數及轉印參數。由於在不同環境條件下成長的石墨烯品質也大不相同,因此我們在章節後段討論眾多影響石墨烯成長品質的因素(溫度、壓力等),並且後續比較這些環境參數予以交叉配對,最後透過實驗分析找出最適合製備高品質石墨烯的條件及參數。 接下來在第五章中,金屬基材(銅)和石墨烯之間的氧化層對於石墨烯轉印影響為論文第二重點。我們發現在石墨烯成長於銅箔表面後,放置於大氣下將在銅和石墨烯的界面形成一層厚度10奈米內的氧化銅薄層,透過此氧化層的介入,銅與石墨烯的作用力將隨著氧化層厚度的增加而減弱,並且進一步幫助銅和石墨烯在轉印階段的分離。實驗設計方面,我們比較了三種常見的石墨烯轉印法(傳統高分子轉印法、氣泡轉印法、靜電力轉印法),隨著放置於大氣下的氧化時間增加,觀察這三種轉印法受影響的程度。另外我們比較數種氧化方式(自然氧化、加溫、泡水),並比較何種氧化方式對於石墨烯之轉印幫助最顯著。 論文的第三部分(第六章),我們發展了一套創新的石墨烯轉印法,透過靜電力吸附長有石墨烯的銅箔於矽基板上,並利用電化學還原法,讓銅箔與石墨烯之間產生氫氣泡,並將銅箔主動帶離石墨烯。由於此轉印法中,不涉及任何化學塗佈或蝕刻步驟,純粹透過物理作用力來移除金屬基材及吸附石墨烯於矽基板,因此透過此法轉印出的石墨烯極為乾淨且不含有任何高分子或蝕刻銅殘留。本章後段我們結合了第五章提到的技巧,透過氧化銅減弱銅與石墨烯的作用力,此氧化層不僅可延遲靜電力的衰退,也能幫助氫氣泡更加容易將銅箔推開,並大幅提升此轉印法轉印後的石墨烯完整性。最後我們將利用分析量測工具討論此雙重物理力轉印法的優缺點,以及未來尚需努力改良的方向。 Graphene, a two-dimensional material formed of a honeycomb lattice structure of 〖sp〗^2 carbon atoms, has been attracting wide attention owing to its remarkable thermal, mechanical and electronic properties. The desire to produce large-scale graphene has motivated a number of recent investigations to develop several methods. In particular, chemical vapor deposition (CVD) is a promising method to grow large-area and high-quality graphene. However, a critical issue in using CVD to grow graphene is the transfer step. In conventional methods of transfer, the graphene is coated with an organic support layer, and the metal substrate is removed with a chemical process. After these transfer steps, chemical residues inevitably remain on the graphene and degrade its quality. This contamination from the transfer step is a fatal disadvantage of CVD graphene. For it to be possible to widely use CVD graphene in industrial applications, the problem of contamination during the transfer steps must be solved. In the first section, we introduce the procedure for fabricating CVD graphene. The details of graphene growth and transfer techniques are described. We also compare different growth parameters to optimize the quality of CVD graphene, and discuss the influences of these factors. In the next part, the utility of an oxidation-assisted transfer technique is confirmed. Oxidation on copper weakens the interaction between graphene and the underlying copper, facilitating the separation of Cu from graphene during the transfer process. In our experiments, three different transfer methods (i.e., traditional PMMA transfer, bubbling transfer, and electrostatic force transfer) are compared to test the influence of oxidation. Furthermore, we attempt to accelerate the oxidation process by raising the oxidizing temperature and humidity, and then we analyze the affects of these intensive oxidizing methods. Finally, we demonstrate a new transfer method using paired physical forces. Electrostatic force is used to attract the graphene film during the transfer process, and another physical force is used to detach the copper foil from the graphene. An electrochemical process causes H_2 bubbles to emerge at the graphene/Cu interface to separate the graphene from the Cu. With this new concept, we obtain graphene without any chemical residues after transfer. Furthermore, given that the strong interaction between graphene and Cu can be weakened by oxidation. The properties of our new transfer method can be improved dramatically by decoupling the interaction between the graphene and the underlying Cu. As a result, we combine these two ideas to optimize the new transfer method by controlling the thickness of oxidation between graphene and Cu. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/51670 |
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顯示於系所單位: | 材料科學與工程學系 |
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