Methods of transferring two-dimensional materials

The advent of two-dimensional (2D) materials, a family of materials with atomic thickness and van der Waals (vdWs) interlayer interactions, offers a new opportunity for developing electronics and optoelectronics. For example, semiconducting 2D materials are promising candidates for extending the Moore's Law. Typical 2D materials, such as graphene, hexagonal boron nitride (h-BN), black phosphorus (BP), transition metal dichalcogenides (TMDs), and their heterostrcutures present unique properties, arousing worldwide interest. In this review the current progress of the state-of-the-art transfer methods for 2D materials and their heterostructures is summarized. The reported dry and wet transfer methods, with hydrophilic or hydrophobic polymer film assistance, are commonly used for physical stacking to prepare atomically sharp vdWs heterostructure with clear interfaces. Compared with the bottom-up synthesis of 2D heterostructures using molecular beam epitaxy (MBE) or chemical vapor deposition (CVD), the construction of 2D heterostructures by transfer methods can be implemented into a curved or uneven substrate which is suitable for pressure sensing, piezoelectric conversion as well as other physical properties’ research. Moreover, the transfer of 2D materials with inert gas protected or in vacuum operation can protect moisture-sensitive and oxygen-sensitive 2D materials from degerating and also yield interfaces with no impurities. The efficient and non-destructive large-area transfer technology provides a powerful technical guarantee for constructing the 2D heterostructures and exploring the intrinsic physical and chemical characteristics of materials. Further development of transfer technology can greatly facilitate the applications of 2D materials in high-temperature superconductors, topological insulators, low-energy devices, spin-valley polarization, twistronics, memristors, and other fields.