Contamination on two-dimensional (2D) crystal surfaces poses serious limitations on fundamental studies and applications of 2D crystals. Surface residues induce uncontrolled doping and charge carrier scattering in 2D crystals, and trapped residues in mechanically assembled 2D vertical heterostructures often hinder coupling between stacked layers. Developing a process that can reduce the surface residues on 2D crystals is important. In this study, we explored the use of atomic force microscopy (AFM) to remove surface residues from 2D crystals. Using various transmission electron microscopy (TEM) investigations, we confirmed that surface residues on graphene samples can be effectively removed via contact-mode AFM scanning. The mechanical cleaning process dramatically increases the residue-free areas, where high-resolution imaging of graphene layers can be obtained. We believe that our mechanical cleaning process can be utilized to prepare high-quality 2D crystal samples with minimum surface residues.

中文翻译：

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机械去除石墨烯表面残留物以进行 TEM 表征

二维 (2D) 晶体表面的污染严重限制了二维晶体的基础研究和应用。表面残留物会导致二维晶体中不受控制的掺杂和电荷载流子散射，而机械组装的二维垂直异质结构中的被困残留物通常会阻碍堆叠层之间的耦合。开发一种可以减少二维晶体表面残留物的工艺非常重要。在这项研究中，我们探索了使用原子力显微镜 (AFM) 从 2D 晶体中去除表面残留物。使用各种透射电子显微镜 (TEM) 研究，我们证实石墨烯样品上的表面残留物可以通过接触模式 AFM 扫描有效去除。机械清洁过程显着增加了无残留区域，可以获得石墨烯层的高分辨率成像。我们相信，我们的机械清洁工艺可​​用于制备具有最少表面残留物的高质量 2D 晶体样品。