Photovoltaic-driven dual optical writing and non-destructive voltage-less reading of polarization in ferroelectric Hf0.5Zr0.5O2 for energy efficient memory devices

Ferroelectric hafnium oxide-based thin films constitute, at present, an intensively investigated candidate material to develop outperforming non-volatile memory devices. We report reading and writing of the ferroelectric polarization with light in Hf0.5Zr0.5O2/Nb:SrTiO3 structures, where light is absorbed at the interface between the two materials, thereby enabling both processes. Reading of ferroelectric polarization is accomplished through the induced short-circuit photocurrents, which is an interesting pathway towards non-destructive reading. Optical writing allows remote and contact-less switching of ferroelectric polarization, without the need for external voltages. The presence or absence of a Pt capping layer is crucial for the aforementioned read/write operations. If top Pt is present, photocarriers flow, resulting in short-circuit photocurrent, whose magnitude is modulated by the induced depolarization field. Instead, if Pt is removed, photocarriers are accumulated at the top surface, eventually producing an optically induced switching of polarization, as revealed by piezoelectric force microscopy observations. These results are highly appealing for the design of novel energy-efficient ferroelectric memory devices actuated with light.