新型机械解理方法在二维材料研究中的应用

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.