Screening effects in ferroelectric resistive switching of BiFeO3 thin films

Abstract

We investigate ferroelectric resistive switching in BiFeO3 thin films by performing local conductivity measurements. By comparing conduction characteristics at artificially up-polarized domains with those at as-grown down-polarized domains, the change in resistance is attributed to the modification of the electronic barrier height at the interface with the electrodes, upon the reversal of the electrical polarization. We also study the effect of oxygen vacancies on the observed conduction and we propose the existence of a different screening mechanism for up and down polarized domains.

Ionic Gating of Ultrathin and Leaky Ferroelectrics

“…Device fatigue is also an important practical issue worth considering. It is evident that the primary driving force for fatigue in an oxide ferroelectric capacitor is the electromigration of oxygen vacancies to the electrode–ferroelectric interface and the development of oxygen vacancy clusters that can form extended defects capable of pinning domains . IL‐gating of other oxide systems is known to induce oxygen migration.…”

Space-charge Effect on Electroresistance in Metal-Ferroelectric-Metal capacitors

“…3a,b . Then, the polarisation leads to an increase of the barrier height by on the positive bound charges side and a decrease by on the negative bound charges side 40 41 . By combining both imperfect-screening ( Fig.…”

“…Similar and unusual variations of barrier heights were for example reported in inorganic BaTiO 3 -based ferroelectric junctions 12 . For inorganic oxide films, an excess of oxygen vacancies (n-doping defects) resulting from the poor-oxygen atmosphere in fabrication process or surface oxygen exchange close to the top surface may happen 41 50 , and the defect density can be as large as ~10 21 –10 22 charges/cm 3 (ref. 51 , 52 , 53 ).…”

“…The space-charge effect can then be used to design or improve devices. For example, a dedicated surface treatment or spontaneous oxygen exchange close to the top surface 41 50 can form a single charged defects layer only at the interface 2 while almost no charged defects are present at interface 1. Therefore both electrode-imperfect-screening effect and space-charge effect can compete when the polarisation points to interface 1, while space-charge effect is absent when the polarisation points to interface 2.…”

Interface and domain engineering in BiFeO3 thin films

“…Moreover, this effect is considered to be so large in BFO thin films that it is held responsible for the resistive switching effect, i.e. the overall conduction is dependent on the polarization direction [5,20,41,[43][44][45][46][47]. Unfortunately, there is no consensus on the conduction mechanism in oxide ferroelectrics.…”