Large Tunnel Electroresistance with Ultrathin Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> Ferroelectric Tunnel Barriers
Bhagwati Prasad, Vishal Thakare, Alan Kalitsov, Zimeng Zhang, B. D. Terris, R. Ramesh
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.