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.

Ferroelectric polarization and defect-dipole switching in an epitaxial (111) BiFeO3 thin film

“…It indicates that a nonlinear current-voltage dependence across the interfacial layers can affect the apparent coercive voltage, including the intrinsic coercive voltage and a constant voltage arising from the interfacial layers. 25,26 To further understand the defect dipole switching mechanism in BFO thin film, we show the plot of I sw with respect to the reciprocal of the coercive field (E d-c ) of defect dipoles in Fig. 5.…”

“…According to the current limited domain switching model, the voltage (V f ) across ferroelectric capacitor varies incrementally from 0 to V A during the initial pure capacitor charging time. [23][24][25][26] The switching current transient I sw with time t can be then simply described as…”