High-performance semiconductor films with vertical compositions that are designed to atomic-scale precision provide the foundation for modern integrated circuitry and novel materials discovery1,2,3. One approach to realizing such films is sequential layer-by-layer assembly, whereby atomically thin two-dimensional building blocks are vertically stacked, and held together by van der Waals interactions4,5,6. With this approach, graphene and transition-metal dichalcogenides—which represent one- and three-atom-thick two-dimensional building blocks, respectively—have been used to realize previously inaccessible heterostructures with interesting physical properties7,8,9,10,11. However, no large-scale assembly method exists at present that maintains the intrinsic properties of these two-dimensional building blocks while producing pristine interlayer interfaces12,13,14,15, thus limiting the layer-by-layer assembly method to small-scale proof-of-concept demonstrations. Here we report the generation of wafer-scale semiconductor films with a very high level of spatial uniformity and pristine interfaces. The vertical composition and properties of these films are designed at the atomic scale using layer-by-layer assembly of two-dimensional building blocks under vacuum. We fabricate several large-scale, high-quality heterostructure films and devices, including superlattice films with vertical compositions designed layer-by-layer, batch-fabricated tunnel device arrays with resistances that can be tuned over four orders of magnitude, band-engineered heterostructure tunnel diodes, and millimetre-scale ultrathin membranes and windows. The stacked films are detachable, suspendable and compatible with water or plastic surfaces, which will enable their integration with advanced optical and mechanical systems.
We thank D. Talapin, P. L. McEuen and M. Guimaraes for discussions and for helping with preparing the manuscript. This work was mainly supported by the Air Force Office of Scientific Research (FA9550-16-1-0031, FA2386-13-1-4118) and the Nano Material Technology Development Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT, and Future Planning (2012M3A7B4049887). Additional funding was provided by the National Science Foundation (NSF) through the Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM; DMR-1539918) and the Cornell Center for Materials Research (CCMR; NSF DMR-1120296). Material characterizations including electron microscopy were supported by the CCMR (NSF DMR-1120296) and the MRSEC Shared User Facilities at the University of Chicago (NSF DMR-1420709). Device fabrication and characterizations were performed at the Cornell Nanoscale Facility (Grant ECCS-1542081) and the Pritzker Nanofabrication Facility of the Institute for Molecular Engineering at the University of Chicago (NSF NNCI-1542205), both of which are members of the National Nanotechnology Coordinated Infrastructure supported by the National Science Foundation.
A video of mechanical peeling of a 2-inch ML MoS2 film with TRT/PMMA from its growth substrate (SiO2/Si in our experiment).
Delamination process of a ML MoS2 film from the substrate by dipping it into water with no polymer support or chemical treatment
A video of delamination process of a ML MoS2 film from the substrate by dipping it into water with no polymer support or chemical treatment.