以兆赫輻射時域頻譜研究多層石墨烯之電磁特性

Abstract

本論文以兆赫輻射時析頻譜(THz-TDS)進行化學氣相沉積(CVD)石墨烯薄膜之兆赫頻譜電磁特性研究。單層石墨烯薄膜為發展高速電子元件及高敏光電元件等應用之熱門材料，因此以化學氣相沉積法製作大面積品質優良的石墨烯為現今炙手可熱的研究領域。鑑此，本研究針對以CVD製程中使用不同轉移材料所製作出之單層與多層石墨烯薄膜進行電磁特性分析。利用石墨烯薄膜之光電導率模型和經典居德自由電子模型（Drude free electron model）對導電率進行數學擬合同時可得載子濃度、載子散射時間以及載子遷移率等重要物理參數，同時利用傅立葉轉換紅外光譜儀(FTIR)以及拉曼光譜等結合THz-TDS量測結果討論在不同層數與不同製程之石墨烯薄膜特性差異。

We use Terahertz-time domain spectroscopy (THz-TDS) to characterize electromagnetic property of graphene thin film. In particular, the extraordinary properties have made monolayer graphene a promising material for high speed electronic device and high sensitive electro-optical device. Graphene synthesized be CVD has been widely study because of not only the large scale area but also high uniformity of graphene. We then perform the THz-TDS to study the electromagnetic property of multilayer graphene via different transfer material in CVD technique. The Drude free carrier model and graphene optical conductivity model were performed in fitting the THz-TDS conductivity result to extracted values of carrier concentration and carrier mobility in the consideration of intraband transition. FTIR and Raman spectroscopy were both used to determine the properties of graphene.