Ferroelectric and strain-tuned MoSe 2 /Bi 2 O 2 Se van der Waals heterostructure with band alignment evolution.

The vertically stacked two-dimensional van der Waals heterostructure (2D vdWH) provides a unique platform for integrating distinctive properties of various 2D materials by functionalizing the interfacial interaction and regulating its band alignment. Herein, we theoretically propose a new MoSe 2 /Bi 2 O 2 Se vdWH material, in which a zigzag-zipper structure of the Bi 2 O 2 Se monolayer is constructed to model its ferroelectric polarization and maintain a small interlayer mismatch with MoSe 2 . The results show a typical unipolar barrier structure with a large band offset in the conduction band and nearly zero offset in the valence band of MoSe 2 /Bi 2 O 2 Se when the ferroelectric polarization of Bi 2 O 2 Se is back to MoSe 2 , in which the electron migration is blocked and holes can migrate unimpeded. It is also found that the band alignment lies between the type-I and type-II heterostructures and band offsets can be flexibly modulated under the joint action of ferroelectric polarization of Bi 2 O 2 Se and in-plane biaxial tensile and compressive strains. This work would facilitate the development of multifunctional devices based on the MoSe 2 /Bi 2 O 2 Se heterostructure material.