Polarization fatigue in ferroelectric films: Basic experimental findings, phenomenological scenarios, and microscopic features

Abstract

The reduction in switchable polarization of ferroelectric thin films due to electrical stress (polarization fatigue) is a major problem in ferroelectric nonvolatile memories. There is a large body of available experimental data and a number of existing models which address this issue, however the origin of this phenomena is still not properly understood. This work synthesizes the current experimental data, models, and approaches in order to draw conclusions on the relative importance of different macro- and microscopic scenarios of fatigue. Special attention is paid to the role of oxygen vacancy migration and electron injection into the film and it is concluded that the latter plays the predominant role. Experiments and problems for theoretical investigations, which can contribute to the further elucidation of polarization fatigue mechanisms in ferroelectric thin films, are suggested.

First-principles study of spontaneous polarization in multiferroicBiFeO3

“…In reality, switching is thought to occur via domain wall motion, where the key physics is associated with polarization reversal under an applied electric field at interfaces between positively and negatively oriented domain walls. 47 Finally, an alternative explanation for the different polarizations reported in various film and bulk samples would be that different crystal structures are epitaxially stabilized in the films, which in turn possess significantly different polarizations. An alternative tetragonal structure that satisfied this requirement was discussed in a previous paper.…”

Dielectric model of point charge defects in insulating paraelectric perovskites

“…In memory applications the oxygen vacancies cause fatigue. 8 Perhaps the point charge defects should be kept responsible for 1/f noise too.…”

Study of harsh environment operation of flexible ferroelectric memory integrated with PZT and silicon fabric

“…Both fatigue improvement and degradation have been reported with increased temperature. 36 This can be attributed to the composition of the PZT, and deposition and crystallization conditions. For instance, James et al reported that thermal healing is responsible for recovering the piezoelectric properties of PZT after physical tensile cycling fatigue tests.…”