  Heterostructure materials form the basis of much of modern electronics, from
transistors to lasers and light-emitting diodes. Recent years have seen a
renewed focus on creating heterostructures through the vertical integration of
two-dimensional materials, including graphene, hexagonal boron nitride, and
transition metal dichalcogenides (TMDCs). However, fundamental challenges
associated with materials processing have limited material quality and impeded
scalability. We demonstrate a method to convert sub-nanometer metal films
deposited on silicon and sapphire into TMDC heterostructures through
vapor-phase processing. The resulting heterostructures and superlattices
exhibit novel properties compared with stand-alone TMDCs, including reduced
bandgap, enhanced light-matter coupling, and improved catalytic performance.
This robust and scalable synthetic method provides new opportunities to
generate a wide range of artificially stacked 2D superlattices with controlled
morphology and composition.
