Enhanced resistive memory in Nb-doped BaTiO3 ferroelectric diodes

In this study, we report on enhanced resistive memory in BaTiO3-based ferroelectric diodes due to the doping of donors. A large ON/OFF current ratio of ∼2000, about two orders of magnitude higher than that of Au/BaTiO3/SrRuO3, is achieved in a Au/Nb:BaTiO3/SrRuO3 diode at room temperature. This can be ascribed to the enhanced ferroelectric-modulation on the potential barrier at the Nb:BaTiO3/SrRuO3 interface associated with the (NbTi4+5+)· donors, which gives rise to an efficient control of device transport between a bulk-limited current in the ON state and an interface-limited Schottky emission in the OFF state. In contrast, the resistance switching is suppressed in a Au/Fe:BaTiO3/SrRuO3 device since the (FeTi4+3+)′ acceptors suppress semiconducting character of the BaTiO3 thin film and make the polarization-modulation of the band diagram negligible. The present work facilitates the design of high-performance resistive memory devices based on ferroelectric diodes with controllable charged defects.