Large Tunnel Electroresistance with Ultrathin Hf0.5Zr0.5O2 Ferroelectric Tunnel Barriers

Abstract

AbstractHafnia‐based ferroelectric tunnel junctions (FTJs) hold great promise for nonvolatile memory and emerging data storage applications. In this article, a large tunnel electroresistance effect with ultrathin Hf0.5Zr0.5O2 (HZO) barrier based FTJs is reported. Robust ferroelectricity is achieved with ≈1 nm films by stabilizing the rhombohedral polar phase of HZO (R‐HZO) through a large compressive strain, induced by growing the film epitaxially on a SrTiO3 (001) substrate. The OFF/ON ratio of the junction resistance at zero bias is about 135 with ≈1 nm thick barrier, which increases to ≈105 with increasing the barrier thickness to ≈2.5 nm. The resistance‐area product (RA) of tunnel junctions is reduced by nearly three orders of magnitude by using an ≈1 nm R‐HZO barrier as compared with typically reported RA values for doped‐HfO2 barrier based FTJs, which significantly improves signal‐to‐noise ratio during the read operation. These results set the stage for further exploration of Hafnia‐based FTJs for non‐volatile memory applications.