Wafer-scale ultrathin and uniform van der Waals ferroelectric oxide

Ferroelectrics have great potential for nonvolatile memory and next-generation electronics, but conventional ferroelectric oxide films generally suffer structural nonuniformity, interfacial depolarization, and performance degradation, particularly when downscaled to advanced technology nodes. We demonstrate uniform, wafer-scale synthesis and back-end-of-line–compatible integration of ultrathin van der Waals (vdW) high-dielectric constant ferroelectric oxide Bi 2 SeO 5 , retaining an optimal coercive field and robust ferroelectricity at monolayer thickness. Ultrathin vdW ferroelectric oxides formed atomically uniform interfaces with two-dimensional semiconductors and yielded ferroelectric field-effect transistor (FeFET) arrays with a low operating voltage (0.8 volts), exceptional cycling endurance (>1.5 × 10 12 cycles), fast write speed (20 nanoseconds), high on/off ratio (10 6 ), 10-year retention, ultralow energy consumption (2.8 femtojoules per bit per square micrometer), and