Van der Waals trilayers and superlattices: Modification of electronic structures of MoS2 by intercalation

TL;DR

This study uses first-principles calculations to explore how intercalating different monolayers between MoS2 layers can modify their electronic properties, revealing pathways to engineer 2D heterostructures with desired electronic characteristics.

Contribution

It provides new insights into how intercalation of various 2D monolayers affects the electronic structures of MoS2 trilayers and superlattices, guiding the design of tailored 2D heterostructures.

Findings

BN effectively decouples MoS2 layers, restoring monolayer electronic structure.

Intercalation of MoSe2 or WSe2 induces an indirect-to-direct bandgap transition.

MoS2/WS2 trilayer retains indirect bandgap, unlike MoSe2/WSe2 cases.

Abstract

We perform a comprehensive first-principles study of the electronic properties of van der Waals (vdW) trilayers via intercalating a two-dimensional (2D) monolayer (ML = BN, MoSe2, WS2, or WSe2) between MoS2 bilayer to form various MoS2/ML/MoS2 sandwich trilayers. We find that the BN monolayer is the most effective sheet to decouple the interlayer vdW coupling of the MoS2 bilayer, and the resulting sandwich trilayer can recover the electronic structures of the MoS2 monolayer, particularly the direct-gap character. Further study of the MoS2/BN superlattices confirms the effectiveness of the BN monolayer for the decoupling of the MoS2-MoS2 interaction. In addition, the intercalation of transition-metal dichalcogenide (TMDC) MoSe2 or WSe2 sheet renders the sandwich trilayer undergoing an indirect-gap to direct-gap transition due to the newly formed heterogeneous S/Se interfaces. In contrast, the MoS2/WS2/MoS2 sandwich trilayer still retains the indirect-gap character of the MoS2 bilayer due to the lack of the heterogeneous S/Se interfaces. Moreover, the 3D superlattice of the MoS2/TMDC heterostructures also exhibits similar electronic band characters as the MoS2/TMDC/MoS2 trilayer heterostructures, albeit slight decrease of the bandgap than the trilayers. Compared to the bulk MoS2, the 3D MoS2/TMDC superlattice can give rise to new and distinctive properties. Our study offers not only new insights into electronic properties of the vdW multilayer heterostructures but also guidance in designing new heterostructures to modify electronic structures of 2D TMDC crystals.