• • In-situ oxidation of Bi2O2Se at temperatures below 400°C yields wafer-scale α-Bi2SeO5, a van der Waals ferroelectric oxide with robust ferroelectricity down to the monolayer limit, enabling low-voltage operation below 1 V.
• • The α-Bi2SeO5 dielectric exhibits a relative permittivity of ~24 and a Curie temperature of ~880 K, ensuring thermal stability and high capacitive coupling for scaled devices.
• • The native ferroelectric buffer eliminates parasitic interlayers and trap states at the interface, mitigating threshold drift and fatigue, thereby enhancing endurance and retention in 2D FeFETs.
• • Precise regulation of the oxidation layer thickness allows uniform and controllable ferroelectric gate stacks, addressing the nucleation challenge on dangling-bond-free 2D surfaces and facilitating monolithic 3D integration.