聚焦離子束顯微鏡(Focused ion beam, FIB)是一個多功能且強大的材料分析及試片製備儀器,被廣泛用來製作高品質的穿透式電子顯微鏡(Transmission electron microscopy, TEM)之橫截面(Cross-sectional)試片,其試片具有定點操作、厚度均勻且薄、可觀察區域大等特性。然而,FIB製作之平面視角(Plan-view)試片卻鮮少有文獻研究,並且現有的方法都會對試片表面造成汙染及破壞,不適用於二維奈米薄膜材料上。為改善現有分析技術的不足之處,本論文提出了利用FIB製作新型態平面視角的TEM試片,成功地應用於單層石墨烯系統,並經過電子繞射、高解析TEM影像以及歐傑電子譜儀(Auger electron microscopy)的分析證實試片沒有明顯的汙染與破壞產生。本論文也利用平面視角的TEM繞射分析、拉曼光譜儀(Raman spectroscopy)、以及橫截面高解析TEM來分析石墨烯的層數及堆疊型態,發現實驗結果與過去文獻所觀察的不一致,結果顯示對於二維奈米薄膜材料的微結構或許還有許多探討的空間。
Focused ion beam(FIB)is a versatile and powerful instrument for materials analysis and sample preparation, and is widely used to fabricate cross-sectional TEM specimens with site-specific preparation, uniform-thinckness, and large observation area. However, on the other hand, FIB-based preparation methods for plan-view specimens are seldom reported yet, and the proposed methods would damage the sample surface during FIB process, harmful to two-dimensional atomic layer materials, such as graphene, MoS2, etc. In this study, we propose a new plan-view TEM specimen preparation method using FIB, which is suitable for single-layer graphene. The results of electron diffraction analysis, high-resolution TEM, and Auger electron microscopy show that the sample surface remains clean and structural-pristine after the fabrication process. We also judge the stacking type and layer number of graphene by plan-view TEM analysis, Raman spectroscopy and high-resolution cross-sectional TEM analysis. We find that determinatnion of the layer numbers of a graphene sheet by Raman analysis is not consistent with the way reported in literatures. Further analysis is still required for understanding the microstructure of two-dimensional atomic layer materials.