2023, Strong interlayer coupling in twisted transition metal dichalcogenide moiré superlattices, Advanced Materials

2023, Strong interlayer coupling in twisted transition metal dichalcogenide moiré superlattices, Advanced Materials

Abstract:

Moiré superlattices in twisted van der Waals materials offer a powerful platform for exploring light-matter interactions. The periodic moiré potentials in moiré superlattices can induce strongly correlated quantum phenomena such as moiré excitons, superconductivity and the Mott-insulating state, all of which depend on the moiré potential associated with the interlayer coupling at the interface. However, moiré superlattices are primarily prepared by the mechanical exfoliation technique and the manual stacking method, where the transfer methods easily cause interfacial contamination, and the preparation of high-quality bilayer two-dimensional materials with small twist angles by direct growth methods remains a significant challenge. Here, we synthesized the WSe2/WSe2 homobilayer with different twist angles by a CVD method using a heteroatom-assisted growth technique. Using the low-frequency Raman scattering, the uniformity of the moiré superlattices were mapped to demonstrate the strong interfacial coupling of the CVD-fabricated twist-angle homobilayer. The moiré potential depths of the CVD-grown and artificially stacked homostructures with twist angles of 1.5° were 115 and 45 meV (an increase of 155%), indicating that the depth of the moiré potential can be modulated by the interfacial coupling. Our results open a new avenue to study the modulation of moiré potential by strong interlayer coupling and provide a foundation for developing twistronics.

Keywords: Moiré superlattices, Interlayer coupling, WSe2/WSe2 homobilayer, Moiré potential 

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