All Dry Transfer Processes Utilizing Au Exfoliation for Predetermined Shapes of Transition Metal Dichalcogenide.

Two-dimensional (2D) materials have attracted significant attention owing to their exceptional electrical and optical properties. The high-quality monolayer 2D materials are usually fabricated by mechanical exfoliation from bulk single crystals using a scotch tape method, limiting the flake size and production yield. Extensive efforts have been made to increase the production yield and size by using an Au-assisted process, such as the modified mechanical exfoliation method. However, the wet-etching processes are inevitable in the scalable Au-assisted mechanical exfoliation method, which causes defect formation and unintentional contamination, leading to a quality decrease in the monolayer 2D material flakes. Here, we developed a Au-assisted all dry transfer method without any wet process for fabricating 2D materials and their van der Waals (vdW) heterostructures. The developed dry transfer technique using patterned Au substrates and h-BN on polymer stamps gives us a large area and designed shape of monolayer 2D materials and their vdW heterostructures with clean interfaces. It will be beneficial for building high-quality vdW heterostructures, allowing us to explore and develop more potential applications in electrical and optical devices based on monolayer 2D materials.