Measurement of Nonlinear Current–Voltage Dependence of Interfacial Passive Layers for Ferroelectric Thin Films

Abstract

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.