Phase-field modeling of switchable diode-like current-voltage characteristics in ferroelectric BaTiO₃

A self-consistent model has been proposed to study the switchable current-voltage (I-V) characteristics in Cu/BaTiO₃/Cu sandwiched structure combining the phase-field model of ferroelectric domains and diffusion equations for ionic/electronic transport. The electrochemical transport equations and Ginzburg-Landau equations are solved using the Chebyshev collocation algorithm. We considered a single parallel plate capacitor configuration which consists of a single layer BaTiO₃ containing a single tetragonal domain orientated normal to the plate electrodes (Cu) and is subject to a sweep of ac bias from -1.0 to 1.0V at 25°C. Our simulation clearly shows rectifying I-V response with rectification ratios amount to 10². The diode characteristics are switchable with an even larger rectification ratio after the polarization direction is flipped. The effects of interfacial polarization charge, dopant concentration, and dielectric constant on current responses were investigated. The switchable I-V behavior is attributed to the polarization bound charges that modulate the bulk conduction.