Scalable Transfer of Suspended Two-Dimensional Single Crystals

Large-scale suspended architectures of various two-dimensional (2D) materials (MoS2, MoSe2, WS2, and graphene) are demonstrated on nanoscale patterned substrates with different physical and chemical surface properties, such as flexible polymer substrates (polydimethylsiloxane), rigid Si substrates, and rigid metal substrates (Au/Ag). This transfer method represents a generic, fast, clean, and scalable technique to suspend 2D atomic layers. The underlying principle behind this approach, which employs a capillary-force-free wet-contact printing method, was studied by characterizing the nanoscale solid-liquid-vapor interface of 2D layers with respect to different substrates. As a proof-of-concept, a photodetector of suspended MoS2 has been demonstrated with significantly improved photosensitivity. This strategy could be extended to several other 2D material systems and open the pathway toward better optoelectronic and nanoelectromechnical systems.