Zhang Baoqing, Zhang Zihao, Han Hecheng, Ling Haotian, Zhang Xijian, Wang Yiming, Wang Qingpu, Li Hu, Zhang Yifei, Zhang Jiawei, Song Aimin
Shandong Technology Center of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan, 250100, China.
Suzhou Research Institute, Shandong University, Suzhou, 215123, China.
Nano Lett. 2023 Oct 11;23(19):9170-9177. doi: 10.1021/acs.nanolett.3c01722. Epub 2023 Jul 26.
Two-dimensional (2D) materials possess unique properties primarily due to the quantum confinement effect, which highly depends on their thicknesses. Identifying the number of atomic layers in these materials is a crucial, yet challenging step. However, the commonly used optical reflection method offers only very low contrast. Here, we develop an approach that shows unprecedented sensitivity by analyzing the brightness of dark-field optical images. The brightness of the 2D material edges has a linear dependence on the number of atomic layers. The findings are modeled by Rayleigh scattering, and the results agree well with the experiments. The relative contrast of single-layer graphene can reach 70% under white-light incident conditions. Furthermore, different 2D materials were successfully tested. By adjusting the exposure conditions, we can identify the number of atomic layers ranging from 1 to over 100. Finally, this approach can be applied to various substrates, even transparent ones, making it highly versatile.
二维（2D）材料具有独特的性质，这主要归因于量子限制效应，而该效应高度依赖于它们的厚度。确定这些材料中的原子层数是关键但具有挑战性的一步。然而，常用的光学反射方法对比度非常低。在此，我们开发了一种方法，通过分析暗场光学图像的亮度显示出前所未有的灵敏度。二维材料边缘的亮度与原子层数呈线性关系。这些发现通过瑞利散射进行建模，结果与实验吻合良好。在白光入射条件下，单层石墨烯的相对对比度可达70%。此外，不同的二维材料也成功得到测试。通过调整曝光条件，我们能够识别从1到超过100的原子层数。最后，这种方法可应用于各种衬底，甚至是透明衬底，使其具有高度的通用性。
