Abstract We report a Variable Angle Spectroscopic Ellipsometry (VASE) characterization of the surface of CVD-grown bilayer and trilayer graphene produced by multiple transfer on SiO2/Si and polyethylene terephthalate (PET) substrates. The graphene layers are randomly stacked. The study of the optical properties of single- and few-layer graphene on PET by means of VASE, which has not been published yet, could be useful in the light of novel graphene-based flexible and stretchable electronics applications. The Lorentz models proposed for the optical response of bilayer and trilayer graphene samples fit very well the experimental data. Some interesting properties have been observed. A never-before-reported absorption peak at ~ 3 eV on bilayer and trilayer graphene on SiO2/Si is discussed. The absorption peak due to resonant excitons has been found at ~ 4.4 eV on bilayer graphene on SiO2/Si and its value is red-shifted from ~ 4.6 eV in monolayer graphene to ~ 4.4 eV in bilayer graphene. This peak shift has not been observed on bilayer graphene on PET substrates.

中文翻译：

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湍层 CVD 生长的双层和三层石墨烯的可变角度光谱椭偏仪表征

摘要 我们报告了通过在 SiO2/Si 和聚对苯二甲酸乙二醇酯 (PET) 基材上多次转移制备的 CVD 生长双层和三层石墨烯表面的可变角度光谱椭偏仪 (VASE) 表征。石墨烯层是随机堆叠的。通过 VASE 研究单层和少层石墨烯在 PET 上的光学特性（尚未发表）可能有助于基于石墨烯的新型柔性和可拉伸电子应用。为双层和三层石墨烯样品的光学响应提出的洛伦兹模型与实验数据非常吻合。已经观察到一些有趣的特性。讨论了在 SiO2/Si 上的双层和三层石墨烯上的~3 eV 处以前从未报道过的吸收峰。在 SiO2/Si 上的双层石墨烯上发现共振激子引起的吸收峰约为 4.4 eV，其值从单层石墨烯中的~4.6 eV 红移到双层石墨烯中的~4.4​​ eV。在 PET 基材上的双层石墨烯上尚未观察到这种峰移。