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標題: | 低損傷電漿改質的功能化石墨烯之特性及應用 Characterizations and Applications of Functionalized Graphene through the Low-Damage Plasma Treatment |
作者: | Chun-Hsuan Lin 林駿璿 |
指導教授: | 林致廷(Chih-Ting Lin) |
關鍵字: | 石墨烯,低損傷電漿,電漿改質,石墨烯表面改質,感測元件, Graphene,Low-Damage Plasma,Plasma-Functionalization,Graphene Surface-Functionalization,Sensing Devices, |
出版年 : | 2019 |
學位: | 博士 |
摘要: | 由於石墨烯優越的物理性質,因此被認為是新一代電子材料,而且石墨烯目前已經應用於各領域的元件,包括光電元件、電子元件以及復合式材料等,然而,功能化的石墨烯不僅可以改善石墨烯的物理特性,並且可進一步提高石墨烯元件的性能,因此,對於改質石墨烯之研究主題,顯示出其重要性和潛力。
本研究是利用低損傷電漿系統,對石墨烯進行改質,探討其改質後的材料鍵結組成、電性與物理特性的變化、以及對濕度感測的應用。使用低損傷氫氧電漿對雙層石墨烯改質後,由拉曼光譜量測結果得知,可以藉由增加改質的時間,穩定地調控石墨烯改質的程度,而且低損傷電漿系統中的互補式遮版架設,阻擋了大部分的離子轟擊與此外光輻射,因此大大降低對石墨烯的改質傷害,由XPS光譜量測結果分析顯示,雙層石墨烯進行氫氧改質後,可以有效增加羧基與羥基的組成比例,特別是石墨烯表面C-OH+COOH的組成比例,最高有著67%增加,而且經由水仰角量測結果得知,雙層石墨烯表面的水仰角減少了75.3%,這是由於C-OH+COOH的組成比例增加所導致,使得雙層石墨烯表面由疏水性轉變為親水性。 我們再以氫氧改質成效,應用於濕度感測元件,然而因C-OH+COOH的組成比例增加,是提升石墨烯表面親水性之重要因素,使得改質後的雙層石墨烯表面,可以吸取更多的水氣,結合石墨烯表面的π電子,最高增強30%石墨烯感測元件對濕度的靈敏度,而且在溼度、酒精與IPA的選擇性上,也由於形成C-OH+COOH在石墨烯表面的鍵結,導致其表面π電子的比例減少,因此對其他氣體分子靈敏度降低,使得選擇性也有35%的改善,成功藉由氫氧低損傷電漿改質,提升了石墨烯感測元件對於濕度的感測效能。 再藉由低損傷電漿系統,進行氮改質雙層石墨烯,氮氣本身活性小,難在石墨烯表面進行鍵結,且低損傷電漿系統中有互補式遮版的架設,阻絕伴隨改質的離子轟擊與此外光輻射,因而氮原子僅藉由擴散機制,對石墨烯進行改質,這降低氮改質石墨烯的成效,但我們再氮改質製程中發現,在石墨烯的基板上加熱,利用溫度的效應,可以促使氮改質石墨烯的形成,並且藉由加熱溫度的調整,可以穩定控制氮改質石墨烯的程度,成功在基板加熱125°C時,有著10.4%的氮氣改質鍵結比例,最後我們再相較先前文獻中,傳統電漿氮改質石墨烯的成果,結果顯示,我們氮改質的製程,是個優質且卓越的改質製程,對於氮改質石墨烯的製程上,是相當大的研究突破。 因此,經由低損傷電漿系統,可以精準且穩定地對雙層石墨烯,進行表面改質,並且成功提高了石墨烯濕度感測元件之性能,對於未來石墨烯材料改質的研究探討,以及石墨烯元件上的應用與開發,有著相當高的潛力與價值。 Graphene has been considered to be a next-generation electronic material due to its fundamental physical properties. In addition, it has been used for different applications in optoelectronic devices, electronic components, and composite materials, etc. However, the functionalization of graphene can even improve the physical properties of graphene and enhance the performance of graphene based devices further. Therefore, the topic of functionalized graphene has exhibited the importance and potential. In this work, we studied surface-functionalization effects of graphene through a low-damage plasma treatment. As a result, the low-damage plasma functionalization of bilayer graphene could hold both the key characteristics of surface functionalization and electrical transport properties of graphene. To characterize the functionalized bilayer graphene, Raman and X-ray photoelectron (XPS) spectroscopies were used to determine the degree of defects and functionalization. At the same time, the degree of wettability of the functionalized bilayer graphene surface was determined by optical contact angle (CA) measurements. Based on experimental results, the compositional ratio of C-OH+COOH was found to increase 67% according to the analysis of XPS spectra after O2/H2 low-damage plasma treatment. This treatment effect can also be found with 75.3% decrease in the CA of water droplet on graphene. The presented process technique of controllable wettability through low-damage plasma treatment can be employed for potential application in graphene-based sensors/devices. We also investigated humidity sensing performance of O2/H2 modified bilayer graphene. The increase of the compositional ratios of C-OH bond and COOH bond are important factors to enhance the wettability transitions on graphene surface. Compared with non-modified bilayer graphene, the humidity sensing response of the modified bilayer graphene can be improved by 30% and sensing selectivity to ethanol can be enhanced by 35%. Therefore, the C-OH+COOH bonding and π-electron modification on the bilayer graphene surface can enhance the adsorption of the water molecules and lead to the improvement of the humidity sensing response. These results show low-damage plasma offers a good method to modify bilayer graphene sensing material for humidity sensing applications. Finally, we developed a method for nitrogen-modification graphene by the heating substrate temperature with low-damage plasma treatment. The results of Raman and XPS spectra demonstrate that the effect of heating is advantageous to enhance the nitrogen-modification on bilayer graphene samples. In addition, the behavior of the nitrogen-modification ratio is similar to the behavior of ID/IG ratio. This demonstrates outstanding nitrogen-modification by low-damage plasma treatment. Based on our experimental results, the nitrogen-modification ratio can achieve 10.4% with 125 °C heating temperature. The nitrogen modified bilayer graphene retains a good electrical transmission further contribute the future develop of graphene based devices. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/73442 |
DOI: | 10.6342/NTU201900738 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
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