Large Tunnel Electroresistance with Ultrathin Hf 0.5 Zr 0.5 O 2 Ferroelectric Tunnel Barriers

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 Hf0.5Zr0.5O2 (HZO) barrier based FTJs is reported. Robust ferroelectricity is achieved with approximate to 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 approximate to 1 nm thick barrier, which increases to approximate to 10(5) with increasing the barrier thickness to approximate to 2.5 nm. The resistance-area product (RA) of tunnel junctions is reduced by nearly three orders of magnitude by using an approximate to 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.