Multiple Conformal-Contact Transfer of Large-Area Crack-Free Transition Metal Dichalcogenide Stacks

Abstract Atomically-thin two-dimensional (2D) transition metal dichalcogenides (TMDs) have emerged as an ideal platform for both physics investigation and device applications. By stacking different layers into homo- or hetero-structures, an extra degree of freedom is involved in further tuning their properties, thereby boosting scenarios in twistronics, moiré photonics and optoelectronics. However, interfacial imperfections such as contaminations and cracks, frequently occur during the layer stacking sequence and accumulate layer by layer, greatly degenerating the interface quality. In this study, we developed a multiple conformal-contact transfer method to construct TMD stacks with crack-free intrinsic interfaces. The design of a deformable buffer layer is crucial to guarantee the conformal contact and intact transfer of each layer, contributing to the successful construction of centimetre-scale TMD stacks up to 8 layers. Precise control over spatial location and interlayer twist angle is also feasibly achieved, evidenced by the stacking-dependent interlayer exciton effects in WS2-WSe2 heterostructures. This work provides a facile and precise approach for architecting 2D stacks with perfect interfaces, which will further accelerate the customized design for their device functionalization.