Strain-engineered and polarization-switchable 2D BP/Ga2O3 heterostructures with reversible metal–semiconductor transitions

Abstract

Two-dimensional (2D) van der Waals (vdW) heterostructures with inherent ferroelectricity hold significant promise for advancing next-generation electronic devices. In this work, we systematically examine the structural and electronic properties of boron phosphide/Ga₂O₃ (BP/Ga₂O₃) ferroelectric heterostructures with different polarizations using first-principles calculations. Our findings reveal that the reversal of the polarization direction in the ferroelectric Ga₂O₃ monolayer induces a metal-to-semiconductor transition: the upward-polarized configuration exhibits metallic behavior, while the downward-polarized configuration retains semiconducting characteristics. Additionally, the metallic state with type-III band alignment and the semiconductor state with type-II band alignment remain robust under both biaxial and vertical strains, respectively. A moderate energy barrier of 0.676 eV between the two polarization states further supports the potential for room-temperature operation. Finally, we explore the potential applications of the BP/Ga₂O₃ heterostructure in nanoscale ferroelectric memory devices. These results establish the BP/Ga₂O₃ vdW heterostructure as a robust platform for designing high-performance ferroelectric switches and non-volatile memory devices.

Graphical abstract