Low Voltage Operation of Ferroelectric AlScN Films by Oxygen Profiling

Abstract

A method to reduce the high coercive field (E_c) of ferroelectric (FE) Al_0.7Sc_0.3N films was proposed. By proper oxygen incorporation to form Al_0.7Sc_0.3O_0.2N_0.8, E_c reduction from 3.8 to 2.8 MV/cm was achieved while maintaining a high remnant polarization (P_r) of over 90 µC/cm². The E_c reduction is presumably caused by the O and Al atom complex vacancies; different from the Sc-atom induced distortion to decrease the ratio of wurtzite lattice constant (c/a). A dielectric constant increase from 17 to 30 supports the E_c reduction. By designing the oxygen depth profile in the film, FE property was obtained with a thickness down to 7 nm. Even the E_c increase with thinner thickness is still presented, a ferroelectric switching was confirmed at a voltage below 5 V.