Tunable type-II band alignment and electronic structure of C3N4/MoSi2N4 heterostructure: Interlayer coupling and electric field

In this work, we perform a first-principle study to investigate the atomic and electronic structures of the C3N4/MoSi2N4 van der Waals heterostructure (vdWH) as well as its tunable electronic structure via interlayer coupling and an external perpendicular electric field. The C3N4/MoSi2N4 vdWH is structurally and thermodynamically stable at room temperature. Our results demonstrate that the C3N4/MoSi2N4 vdWH exhibits a semiconducting characteristic with a direct band gap of 1.86/2.66 eV as given by the PBE/HSE06 calculation. This value of band gap conveniently lies in the visible light energy range, thus unraveling the strong optical absorption of C3N4/MoSi2N4 vdWH in the technologically important visible light regime. The band edges of the C3N4/MoSi2N4 vdWH separately from the C3N4 and MoSi2N4 layers, thus resulting in a type-II band alignment, which is highly desirable for achieving efficient electron-hole separation. Remarkably, the electronic structure and the band alignment types can be flexibly tuned between type-I and type-II by applying an external electric field, by changing the interlayer distance and by applying the in-plane strain. Our findings reveal the potential of C3N4/MoSi2N4 vdWH as a tunable hybrid material with strong potential in optoelectronic applications. © 2022 American Physical Society.