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拉曼光谱技术是探测和分析石墨烯特性最有效的方法之一,其拉曼光谱信号主要包括D峰、G峰和2D峰。由于通常不受外界因素的影响,2D峰与G峰的强度比可以用来分析石墨烯的基本特性。以SiO_2/Si基底上的石墨烯为研究对象,基于多层膜系菲涅尔理论,研究了2D峰与G峰的强度比随石墨烯层数(厚度)变化的关系。研究结果表明2D峰与G峰的强度随着石墨烯层数增加而减小。进一步,研究了SiO_2厚度对拉曼光谱增强因子以及2D峰与G峰的强度比的影响,得到其最大增强因子和强度比分别为5.15、4.21和13.1。最后,讨论了2D峰与G峰的强度比与激发激光波长的关系,结果表明2D峰与G峰强度比随激发波长的增加先增加后减小,其最大比值为13.1,对应的激发波长为585nm。
Raman spectroscopy is one of the most effective methods for detecting and analyzing the properties of graphene. Its Raman spectrum mainly includes D-peak, G-peak and 2D-peak. The intensity ratio of the 2D peak to the G peak can be used to analyze the basic properties of graphene because it is generally unaffected by external factors. Taking graphene on SiO 2 / Si substrate as the research object, the relationship between the intensity ratio of 2D peak and G peak with the number of graphene layers (thickness) was studied based on the Fresnel theory of multilayer film. The results show that the intensities of 2D and G peaks decrease with the increase of graphene layers. Furthermore, the effects of SiO 2 thickness on Raman spectrum enhancement factor and intensity ratio of 2D peak to G peak were studied. The maximum enhancement factor and intensity ratio were 5.15, 4.21 and 13.1, respectively. Finally, the relationship between the intensity ratio of 2D peak and G peak and the excitation laser wavelength is discussed. The results show that the intensity ratio of 2D peak to G peak first increases and then decreases with the increase of excitation wavelength, the maximum ratio is 13.1. The corresponding excitation wavelength is 585nm.