Large Tunnel Electroresistance with Ultrathin Hf_0.5Zr_0.5O₂ Ferroelectric Tunnel Barriers

Abstract

Abstract Hafnia‐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 Hf 0.5 Zr 0.5 O 2 (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 SrTiO 3 (001) substrate. The OFF/ON ratio of the junction resistance at zero bias is about 135 with ≈1 nm thick barrier, which increases to ≈10 5 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‐HfO 2 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.