Photoactive electrically switchable van der Waals semiconductor NbOI2

Room temperature van der Waals ferroelectric materials whose ferroelectricity may survive down to atomic layer limit are highly desirable for device miniaturization. In this article, we present the optically active reconfigurable room temperature rectification in a recently predicted ferroelectric van der Waals material NbOI2. NbOI2 devices with a thin (∼17-unit cells) single crystalline channel and inert graphite electrodes were assembled into two-terminal devices which showed >100 × photoresponse to 405 nm laser. By DC poling on a 1-μm-channel NbOI2 device, the photocurrent changed from symmetric to single-Schottky-diode type. The polarity of such rectification can be switched back and forth by DC poling along opposite directions. Such reconfigurability evidences the existence of in-plane room temperature ferroelectricity in thin NbOI2 and its potential in nonvolatile optoneuromorphic computing and nonvolatile technologies.