A single-phase epitaxially grown ferroelectric perovskite nitride

The integration of ferroelectrics with semiconductors is crucial for developing functional devices, such as field-effect transistors, tunnel junctions, and nonvolatile memories. However, the synthesis of high-quality single-crystalline ferroelectric nitride perovskites has been limited, hindering a comprehensive understanding of their switching dynamics. Here we report the synthesis and characterizations of epitaxial single-phase ferroelectric cerium tantalum nitride (CeTaN₃) on both oxides and semiconductors. The polar symmetry of CeTaN₃ was confirmed by observing the atomic displacement of central ions relative to the center of the TaN₆ octahedra, as well as through optical second harmonic generation. We observed switchable ferroelectric domains using piezoresponse force microscopy, complemented by the characterization of square-like polarization-electric field hysteresis loops. The remanent polarization of CeTaN₃ reaches approximately 20 microcoulomb per square centimeter at room temperature, consistent with theoretical calculations. This work establishes a vital link between ferroelectric nitride perovskites and their practical applications, paving the way for next-generation information and energy storage devices.