Applications of new exfoliation technique in study of two-dimensional materials
Xu Hong1\2, Meng Lei1\3, Li Yang1\4, Yang Tian-Zhong1, Bao Li-Hong1, Liu Guo-Dong1, Zhao Lin1, Liu Tian-Sheng4, Xing Jie2, Gao Hong-Jun1, Zhou Xing-Jiang1, Huang Yuan1
1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;2. School of Science, China University of Geosciences, Beijing 100083, China;3. College of Science, Minzu University of China, Beijing 100081, China;4. School of Environment and Safety Engineering, North University of China, Taiyuan 030051, China>
Since the discovery of graphene, mechanical exfoliation technology has become one of the important methods of preparing high-quality two-dimensional (2D) materials. This technology shows some unique advantages in the study of the intrinsic properties of 2D materials. However, traditional mechanical exfoliation method also has some obvious deficiencies, such as low yield ratio and small size of the resulting single-or few-layer flakes, which hinders the research progress in the field of 2D materials. In recent years, we made a series of breakthroughs in mechanical exfoliation technology, and independently developed a new type of mechanical exfoliation method with universality. The core of this new method is to enhance the van der Waals interaction between the layered material and the substrate by changing multiple parameters in the exfoliation process, thereby increasing the yield ratio and area of the monolayer. Taking graphene for example, we can now increase the size of graphene from micron to millimeter, increase over 100000 times in area, and yield ratio more than 95%, in the meantime graphene still maintains very high quality. This new mechanical exfoliation method shows great universality, and high-quality monolayer flake with a size of millimeters or more has been obtained in dozens of layered material systems including MoS2, WSe2, MoTe2, and Bi2212. More importantly, some special structures can be fabricated by optimizing exfoliation parameters, such as bubble and wrinkle structures, which paves the way for the study of these special material systems. Many scientific problems are still worth exploring in the mechanical exfoliation technology, and the breakthrough of this technology will greatly promote the research progress in the field of 2D materials.
Project supported by the National Natural Science Foundation of China (Grant Nos. 11874405, 61474141, 11504439, 11104255) and the Fundamental Research Funds for the Central Universities of Ministry of Education of China.
Xu Hong, Meng Lei, Li Yang, Yang Tian-Zhong, Bao Li-Hong, Liu Guo-Dong, Zhao Lin, Liu Tian-Sheng, Xing Jie, Gao Hong-Jun, Zhou Xing-Jiang, Huang Yuan. Applications of new exfoliation technique in study of two-dimensional materials[J]. Acta Phys. Sin., 2018, 67(21): 218201.