Tunable Band Alignments in 2D Ferroelectric α-In₂Se₃ Based Van der Waals Heterostructures

Two-dimensional (2D) van der Waals (vdW) heterostructures have attracted substantial research interest in recent years, due to their tremendous advantages, such as atomically sharp interfaces, digitally controlled layered components, and unconstraint lattice mismatch, and immense potentials, in electronic and optoelectronic applications. The functionality and performance of such vdW heterostructures critically depend on the band alignment between the constituent layers. In this work, based on systematic first-principles calculations, we demonstrate that by taking advantage of the out-of-plane ferroelectricity of a 2D ferroelectric material α-In2Se3, the band alignments of a large variety of α-In2Se3 based vdW heterostructures can be controllably switched between different types of semiconductor or metal–semiconductor junctions via the polarization reversal of the ferroelectric α-In2Se3 layer upon the application of an external electric field. This work provides a generic guideline for the application of 2D ferroelectric α-In2Se3 in tuning the electronic and optical properties of vdW heterostructures for device applications.