Reversible charge injection-controlled resistance switching in BiFeO3 ferrodiodes

The ferroelectric diode effect is a promising candidate for resistive memory applications, but the precise role of defects in the current switching mechanism remains unclear. Here, we investigated ferroelectric SrRuO3/BiFeO3/SrRuO3 capacitors and observed strong diode current. The capacitors exhibited preferred polarization orientation toward the bottom electrode in the presence of an imprint field, as evidenced by poor polarization retention of upward polarizations at a bias voltage of 1 V. Interfacial defect-mediated charge injection and trapping enabled by negative voltage poling reduced the built-in field and improved the retention property at the expense of reduced diode current. This phenomenon can be reversed by long-time positive voltage poling, allowing the deeply trapped charges to be expelled out of the trap for the rejuvenation of the diode current. Our study provides experimental evidence that interfacial defects modify the diode current in a manner opposite to that of the switched polarization.