Although flakes of two-dimensional (2D) heterostructures at the micrometer scale can be formed with adhesive-tape exfoliation methods, isolation of 2D flakes into monolayers is extremely time consuming because it is a trial-and-error process. Controlling the number of 2D layers through direct growth also presents difficulty because of the high nucleation barrier on 2D materials. We demonstrate a layer-resolved 2D material splitting technique that permits high-throughput production of multiple monolayers of wafer-scale (5-centimeter diameter) 2D materials by splitting single stacks of thick 2D materials grown on a single wafer. Wafer-scale uniformity of hexagonal boron nitride, tungsten disulfide, tungsten diselenide, molybdenum disulfide, and molybdenum diselenide monolayers was verified by photoluminescence response and by substantial retention of electronic conductivity. We fabricated wafer-scale van der Waals heterostructures, including field-effect transistors, with single-atom thickness resolution.

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This article reports on two-dimensional (2D) layered hexagonal BN (h-BN) grown on sapphire by metalorganic vapor phase epitaxy (MOVPE). The highly oriented lattice and hexagonal phase of the epitaxial layers were confirmed by X-ray diffraction, Raman spectrum, and cross-section scanning transmission electron microscopy. The surface of BN over a 2-in. wafer exhibits specific 2D material morphology features for different BN thicknesses, from an atomically flat surface to a honeycomb wrinkle network. The grown epitaxial layers demonstrate a large absorption coefficient (∼10 6 cm −1 ) above the bandgap energy of 5.87 eV with direct band transition behavior. Near-bandgap luminescence at 216.5 nm (5.73 eV) and characteristic defect band recombination at longer wavelengths were observed by cathodoluminescence at 77 K. This wafer-scale MOVPE-grown layered h-BN with different 2D morphology and with near bandgap emission can facilitate applications such as graphene-based electronics, advanced van der Waals heterostructures, and deep UV photonics.