Strain-free MoS2/ZrGe2N4 van der Waals Heterostructure: Tunable electronic properties with type-II band alignment

Abstract

Vertically stacked van der Waals heterostructures (vdW-HS) amplify the scope of two-dimensional materials for emerging technological applications, such as nanodevices and solar cells. Here, we present a first-principles study on the electronic and structural properties of the heterobilayer (HBL) MoS2/ZrGe2N4, which forms a strain-free vdW-HS thanks to the identical lattice parameters of the constituents. This system has an indirect band gap with type-II band alignment with the highest occupied and lowest unoccupied states localized on MoS2 and ZrGe2N4, respectively. Biaxial strain, which generally reduces the band gap regardless of compression or expansion, is applied to tune the electronic properties of the HBL. A small amount of tensile strain leads to an indirect-to-direct transition, shifting the band edges at the center of the Brillouin zone. These results suggest the potential application of HBL MoS2/ZrGe2N4 in optoelectronics devices.