以變溫兆赫輻射時析頻譜研究 石墨烯之電磁特性

Abstract

石墨烯是一種二維材料，由於其特殊的能帶結構，因此為發展新穎的兆赫波光電元件的熱門材料。本研究以化學氣相沉積法製作大面積品質優良的石墨烯，以拉曼光譜探討銅箔純度對石墨烯膜薄品質的影響；以及以變溫兆赫輻射時析頻譜探討不同溫度下石墨烯薄膜之光電導率，接著利用理論擬合分析獲得材料的散射率和電漿頻率，藉由擬合結果得知載子濃度和載子遷移率。藉此我們得知在可觀測溫度範圍內，其散射率為一常數，因此我們認為其貢獻主要不是由聲子散射，而是由雜質散射…等受溫度影響有限之散射機制，導致其對溫度改變沒有影響。

Graphene is a two-dimensional material. Due to its unique energy band structure, is considered a promising material for THz optoelectronic devices. In this work, we report our measurements with Raman spectroscopy and THz optical conductivity of graphene, is deposited on fuse silica substrates by CVD processes, by temperature-dependent terahertz time-domain spectroscopy. The impurity of copper and its treatments can affect the quality of graphene. The intraband scattering rate and plasma frequency can be obtained by fitting with theoretical models. Other physical parameters, including carrier density and carrier mobility, can be deduced from the theoretical fitting. Here, we obtain the scattering rate is a constant with different temperature. This implies the scattering mechanism might be independent of phonon scattering, dependent of impurity scattering.