Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

The time dependence of the domain switching current density, Jsw(t), under pulsed voltages on a ferroelectric parallel‐plate capacitor is the consequence of region‐by‐region polarization reversals across the film. As the distributive coercive voltage of domain nucleation increases from zero to the maximum applied voltage during the capacitor charging time, Jsw(t) is proportional to the domain switching speed at each time. By transforming the spatially inhomogeneous domain nucleation distribution into a temporal distribution of coercive fields (Ec), a local lnJsw versus Ec−1 plot is derived for each domain, following the Merz equation. This provides insight into the independent domain switching dynamics at different nucleation sites in Pb(Zr0.35Ti0.65)O3 thick films over a large current range. Although the activation field of the slope of the lnJsw(t) versus Ec−1 plot varies with film area and temperature, all the plots extrapolate to a single point (J0, E0) from which the ultimate domain switching current density of J0 =1.4 × 108 A cm−2 at the highest field of E0 = 0.20‐0.25 MV cm−1 is derived. Unexpectedly, J0 and E0 are independent of the film thickness and area, after correction for a small interfacial‐layer effect. This analysis provides rigorous evidence for nucleation rate‐limited domain switching with a subpicosecond nucleation time and the relative unimportance of domain forward‐growth time across film thicknesses between 0.14 and 2 μm. This work paves the way to improve the efficiency of ferroelectric thick‐film functionality in electronic and optoelectronic devices with ultrafast clock rates.

Theoretically, interfacial passive layers identified in most ferroelectric thin films are assumed to be highly insulating to tilt polarization–voltage (P–V) hysteresis loops and to reduce the apparent coercive field. Practically, the layers would be leaky under an extremely high field, where the P–V loop remains squared rather than tilted. In this work, we develop a technique to measure the nonlinear current–voltage dependence across the interfacial layers during domain switching. With the aid of this technique, we simulate the interfacial current–voltage relationship by using conventional conduction models. After elimination of the interfacial-layer effect on the coercive-voltage estimation with different film thicknesses, we extract domain switching current dependence of the intrinsic coercive field, irrespective of the film thickness. The thermal activation field derived from domain switching model of the Merz's law is around 1.4 kV/cm, unexpectedly smaller than those in bulk ceramics.

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