Large Switchable Photoconduction within 2D Potential Well of a Layered Ferroelectric Heterostructure.

The coexistence of large conductivity and robust ferroelectricity is promising for high-performance ferroelectric devices based on polarization-controllable highly efficient carrier transport. Distinct from traditional perovskite ferroelectrics, Bi2 WO6 with a layered structure shows a great potential to preserve its ferroelectricity under substantial electron doping. Herein, by artificial design of photosensitive heterostructures with desired band alignment, three orders of magnitude enhancement of the short-circuit photocurrent is achieved in Bi2 WO6 /SrTiO3 at room temperature. The microscopic mechanism of this large photocurrent originates from separated transport of electrons and holes in [WO4 ]-2 and [Bi2 O2 ]+2 layers respectively with a large in-plane conductivity, which is understood by a combination of ab initio calculations and spectroscopic measurements. The layered electronic structure and appropriately designed band alignment in this layered ferroelectric heterostructure provide an opportunity to achieve high-performance and nonvolatile switchable electronic devices.