Department of Physics, Konkuk University, Seoul, 05029, Korea.
Emerging Devices Research Group, Electronics and Telecommunications Research Institute (ETRI), Daejeon, 34129, Korea.
Sci Rep. 2018 Jan 12;8(1):571. doi: 10.1038/s41598-017-19084-1.
Since the successful exfoliation of graphene, various methodologies have been developed to identify the number of layers of exfoliated graphene. The optical contrast, Raman G-peak intensity, and 2D-peak line-shape are currently widely used as the first level of inspection for graphene samples. Although the combination analysis of G- and 2D-peaks is powerful for exfoliated graphene samples, its use is limited in chemical vapor deposition (CVD)-grown graphene because CVD-grown graphene consists of various domains with randomly rotated crystallographic axes between layers, which makes the G- and 2D-peaks analysis difficult for use in number identification. We report herein that the Raman Si-peak intensity can be a universal measure for the number identification of multilayered graphene. We synthesized a few-layered graphene via the CVD method and performed Raman spectroscopy. Moreover, we measured the Si-peak intensities from various individual graphene domains and correlated them with the corresponding layer numbers. We then compared the normalized Si-peak intensity of the CVD-grown multilayer graphene with the exfoliated multilayer graphene as a reference and successfully identified the layer number of the CVD-grown graphene. We believe that this Si-peak analysis can be further applied to various 2-dimensional (2D) materials prepared by both exfoliation and chemical growth.
自从石墨烯成功剥离以来，已经开发出了各种方法来确定剥离石墨烯的层数。目前，光学对比度、拉曼 G 峰强度和 2D 峰线形状被广泛用作石墨烯样品的初步检查手段。尽管 G 峰和 2D 峰的组合分析对于剥离石墨烯样品非常有效，但在化学气相沉积（CVD）生长的石墨烯中，其应用受到限制，因为 CVD 生长的石墨烯由不同的畴组成，畴之间的层状晶轴随机旋转，这使得 G 峰和 2D 峰分析难以用于层数识别。我们在此报告，拉曼 Si 峰强度可以作为多层石墨烯层数识别的通用衡量标准。我们通过 CVD 方法合成了少层石墨烯，并进行了拉曼光谱测量。此外，我们测量了来自不同单个石墨烯畴的 Si 峰强度，并将其与相应的层数相关联。然后，我们将 CVD 生长的多层石墨烯的归一化 Si 峰强度与作为参考的剥离多层石墨烯进行了比较，并成功地识别了 CVD 生长石墨烯的层数。我们相信，这种 Si 峰分析可以进一步应用于通过剥离和化学生长制备的各种二维（2D）材料。
