Wave Function Extent in multilayer van der Waals Heterostructures: A First-Principles Study

A good understanding of interlayer coupling is crucial to designing novel van der Waals heterostructures. The present study examines two types of multilayer heterostructures based on 2D transition-metal dichalcogenides (TMDCs). ABC or ABBC stackings consist of three layers (A - MoS2, B - MoSe2, C - WSe2). By doing so, MoSe2 spatially separates the electron layer (MoS2) from the hole layer (WSe2). TMDCs are stacked in one of three ways in the second type: ABA, ABBA, or AABAA. Depending on stoichiometry, the electrons or holes are localized in the middle part of the heterostructure or delocalized to the outer layers. The majority of the materials studied here are direct gap semiconductors with transitions at K. A type II band alignment is found in all of them. We predict that indirect excitons will be evident in all materials.