利用化學氣相沉積法合成石墨烯並應用於氣體感測器

Synthesis of Graphene by Chemical Vapor Deposition and Its Gas Sensing Application

盧泓(Lu, Hung)

指導教授 ： 李元堯

國立中正大學/工學院/化學工程學系/碩士(2012年)

摘要

本論文以常壓化學氣相沉積法(chemical vapor deposition method )合成石墨烯於銅箔上，並藉由控制實驗參數進行不同層數石墨烯的成長，最後應用於氣體感測器的量測。實驗主要分為兩大部分，第一部分為石墨烯的合成，第二部分為氣體感測的應用。
在石墨烯的合成實驗中，針對不同反應時間及反應物甲烷含量對石墨烯層數成長的影響，發現在同一反應參數中，銅箔表面的石墨烯其層數有不均勻的現象，且石墨烯層數會隨著反應時間的加長(或甲烷含量的增加)而增加。在10分鐘的反應時間中，成長的石墨烯約2~5層；20分鐘約9~11層；60分鐘則上升至50層以上。
在氣體感測特性的量測實驗中，乙烯及氨氣做為感測氣體。首先在乙烯氣體的感測實驗中，探討電極間距對氣體感測的影響，發現當間距越小時，氣體感測的靈敏度較低，但應答時間及恢復時間較短；而在氨氣氣體的感測實驗中，更深入探討石墨烯的層數對氣體感測的影響，發現當使用層數較少的石墨烯為材料時，其靈敏度、應答時間及恢復時間皆優於層數較多的石墨烯。而感測時的溫度亦對氣體感測有一定的影響，200oC時有較短的應答及恢復時間，但在室溫30oC時卻有著最佳的靈敏度。

關鍵字

化學氣相沉積法 ； 石墨烯 ； 氣體感測

並列摘要

The purpose of this study is to synthesize grapheme on copper foils using atmospheric pressure chemical vapor deposition. The growth of layers of graphene can be controlled by experimental parameters,such as reaction time and concentration of methane. The experiments are divided into two parts. One is the synthesis of grapheme, and the gas sensor application.
In the experiments of synthesis of graphene, we focused on the concentration of methane and reaction time on the growth of graphene layers. It was found that graphene layers are not uniform on the surface of copper foil in the same reaction parameters. Graphene layers was increased with increase of the reaction time (or the amount of methane). For example, in the 10 minutes of reaction time, the growth of graphene are about 2 - 5 layers. The growth of graphene are 9 - 11 layers with the 20 minutes reaction time. While the layers of graphene were up to 50 layers in the 60 minutes of reaction time.
In the study of gas sensors, target gas (ethylene and ammonia) were employed. The sensing started with ethylene sensing, using graphene sensor with different electrode spacing. The result found that, with reducing the electrode spacing, the sensitivity decreased, but the response time and recovery time decreased. For the study of ammonia sensing, the effect of graphene layers was conducted. It was found that fewer layers of graphene enhanced the sensitivity, response time and recovery time. In addition, temperature also influence gas sensing, shorter response time and recovery time can be achieved while the study was conducted with higher temperature. However the best sensitivity achieved while the experiment was conducted at room temperature (30oC).

並列關鍵字

CVD ； graphene ； gas sensor

參考文獻

[1] Geim AK, Novoselov KS. The rise of graphene. Nature Materials. 2007;6(3):183-91.

[2] Novoselov KS, Geim AK, Morozov SV, Jiang D, Zhang Y, Dubonos SV, et al. Electric field effect in atomically thin carbon films. Science. 2004;306(5696):666-9.

[3] Du X, Skachko I, Duerr F, Luican A, Andrei EY. Fractional quantum Hall effect and insulating phase of Dirac electrons in graphene. Nature. 2009;462(7270):192-5.

[4] Bolotin KI, Ghahari F, Shulman MD, Stormer HL, Kim P. Observation of the fractional quantum Hall effect in graphene. Nature. 2009;462(7270):196-9.

[5] Lee C, Wei XD, Kysar JW, Hone J. Measurement of the elastic properties and intrinsic strength of monolayer graphene. Science. 2008;321(5887):385-8.