利用低損傷電漿系統在石墨烯氣體感測器上之應用

Abstract

石墨烯 (graphene) 因具備極高的載子遷移率，且對於氣體分子來說具有極大的感測接觸面積，所以是個很具有潛力的氣體感測器。而且，石墨烯是一种類金屬(semimetal)，它所以在製作元件上，石墨烯可以同時具有感測層以及傳輸層特性，這讓石墨烯在各種得分子測量上具有一定的優勢 本論文將以化學氣相沉積法成長大面積的石墨烯於銅箔上，再利用氣泡掀離法把隨機堆疊的雙層石墨烯轉印到目標基板上，接著利用低損傷電漿系統對石墨烯進行表面的官能基修飾，藉由這些表面的改變，也發現了石墨烯對於各種氣體的感測特性(sensing characteristic)隨著各種參數的變化而變化，而一開始我們選定的電漿是以不同時間的氧電漿對石墨烯表面進行改質，除了氧電漿外我們也對氮電漿進行各種的試驗，尋找能將石墨烯表面官能化的最佳參數，並且利用這些表面被官能基改變的石墨烯進行氣體量測。 此外，本實驗也對摻雜前後的單層與雙層石墨烯進行拉曼光譜的分析，同時也藉由X射線光電子光譜儀來分析摻雜時間與石墨烯表面的碳氧比例的關係。

Graphene is a very promising candidate to replace silicon as a channel material for the next generation of transistor due to its extremely high carrier mobility. At the same time, graphene is also a good candidate for carrier transportations and sensing applications because of its unique two-dimensional characteristics. In this work, therefore, it is used as a basic material for modification and sensing. To fabricate graphene in this research work, it was grown on copper foil by chemical vapor deposition and transferred onto the target substrate by using bubble process. After that, the graphene-based gas sensor characteristics was promoted by using low damage plasma modification. Based on this modification process, the sensitivity and selectivity can be improved. To validate the proposed graphene-based sensor, both oxygen and nitrogen were used in the low-damage plasma modification. And four different kinds of gases were also used to examine the sensing characteristics of the modified graphene sensors. To further understand the properties of the modified graphene, the modified graphenes were analyzed by Raman spectrum. At the same time, the modified graphenes were also examined by X-ray photoelectron spectroscopy to understand the ratio between carbon, oxygen, and nitrogen. Therefore, this work demonstrates a potential application for graphene devices.