Sunday, 01 October, 2023

Imaging lattice reconstruction in homobilayers and heterobilayers of transition metal dichalcogenides

A. Rupp, J. Göser, ZJ. Li, I. Bilgin, A. Baimuratov, A. Högele

DOI: 10.1088/2053-1583/acf5fb

Moire interference effects influence profoundly the optoelectronic properties of vertical van der Waals structures. Here we systematically establish secondary electron imaging in a scanning electron microscope as a powerful technique for visualizing reconstruction of moire lattices into registry-contrasting domains in vertical homobilayers and heteorbilayers of transition metal dichalcogenides (TMDs) with parallel and antiparallel alignment. With optimal parameters for contrast-maximizing imaging of high-symmetry registries, we identify distinct crystal realizations of WSe2 homobilayers and MoSe2-WSe2 heterostructures synthesized by chemical vapor deposition. In particular, we find evidence for a mutually exclusive competition between RhX and RhM registries, manifesting in complete reconstruction of bilayer crystals into one distinct registry or alternating large-area domains in RhX and RhM stacking. Our results have immediate implications for the optical properties of registry-specific excitons in layered stacks of TMDs, and demonstrate the general potential of secondary electron imaging for van der Waals twistronics.