Strong Interlayer Coupling in Twisted Transition Metal Dichalcogenide Moire Superlattices

Moire superlattices in twisted van der Waals materials offer a powerful platform for exploring light-matter interactions. The periodic moire potentials in moire superlattices can induce strongly correlated quantum phenomena that depend on the moire potential associated with interlayer coupling at the interface. However, moire superlattices are primarily prepared by mechanical exfoliation and manual stacking, where the transfer methods easily cause interfacial contamination, and the preparation of high-quality bilayer 2D materials with small twist angles by growth methods remains a significant challenge. In this work, WSe2/WSe2 homobilayers with different twist angles by chemical vapor deposition (CVD), using a heteroatom-assisted growth technique, are synthesized. Using low-frequency Raman scattering, the uniformity of the moire superlattices is mapped to demonstrate the strong interfacial coupling of the CVD-fabricated twist-angle homobilayers. The moire potential depths of the CVD-grown and artificially stacked homostructures with twist angles of 1.5 degrees are 115 and 45 meV (an increase of 155%), indicating that the depth of moire potential can be modulated by the interfacial coupling. These results open a new avenue to study the modulation of moire potential by strong interlayer coupling and provide a foundation for the development of twistronics.

Automated summary

WSe2/WSe2 homobilayers with different twist angles were synthesized using a heteroatom-assisted chemical vapor deposition (CVD) technique. The uniformity of the moire superlattices in the homobilayers fabricated by CVD was mapped using low-frequency Raman scattering, demonstrating strong interfacial coupling. The moire potential depths of the CVD-grown and artificially stacked homostructures with a twist angle of 1.5 degrees were 115 and 45 meV (an increase of 155%), indicating the modulation of moire potential depth through interfacial coupling.