Strong interlayer hybridization in the aligned SnS2/WSe2 hetero-bilayer structure

Abstract

The combination of monolayers of different two-dimensional (2D) materials into van der Waals hetero-bilayer structures creates unprecedented physical phenomena, acting as a powerful tool for future devices. Understanding and exploiting these phenomena hinge on knowing the electronic structure and the hybridization of hetero-bilayer structures. Here, we show strong hybridization effects arising between the constitutive single layers of a SnS₂/WSe₂ hetero-bilayer structure grown by chemical vapor deposition. Surprisingly, the valence band maximum position of WSe₂ is moved from the K point for the single layer WSe₂ to the Γ point for the aligned SnS₂/WSe₂ hetero-bilayer. Additionally, a significant photoluminescence quenching is observed for the SnS₂/WSe₂ hetero-bilayer structure with respect to the WSe₂ monolayer. Using photoluminescence spectroscopy and nano-angle-resolved photoemission spectroscopy techniques, we demonstrate that the SnS₂/WSe₂ heterostructure present a type-II band alignment. These findings directly answer many outstanding questions about the electronic band structure and the band offset of SnS₂/WSe₂ hetero-bilayers for envisaging their applications in nanoelectronics.