Resolving performance reliability issues in BiFeO3 domain wall memories

Abstract

The commercialization of high-density ferroelectric domain wall memory has been hindered by reliability challenges, including fatigue and retention loss. In this study, we addressed these issues using prototype domain wall memories fabricated from epitaxial BiFeO₃(110) thin films. The vertical SrRuO₃/BiFeO₃/SrRuO₃ devices showed inconsistent resistive switching behavior during electric cycling due to the susceptible fatigue of the ferroelectric thin film. This susceptibility stems from domain fragmentation, coupled with the formation of various domain walls, resulting in the reduction of switchable polarization. On this basis, planar Pt/BiFeO₃/Pt nanodevices were proposed to resolve this issue, as the created local 71° domain walls in the thin film can be easily eliminated by the electric field with the assistance of the elastic interaction in the domain boundary. Our investigation revealed that space-charge-limited conduction mechanism governed the electrical conduction in the nanodevices, with the current rectification ratio displaying greater insensitivity to electrical cycling compared to vertical devices. Moreover, with the controlled interfacial charge injection through alternating voltage pulse cycling, the polarization retention was improved in electrode gap-reduced nanodevices along with the diminished influence of the depolarization field arising at the artificial domain wall region. We achieved performance-optimized BiFeO₃ nanodevices characterized by exceptional retention and fatigue properties, simultaneously delivering a high current rectification ratio of 100:1.