Non-conventional mechanism of ferroelectric fatigue via cation migration

Abstract

The unique properties of ferroelectric materials enable a plethora of applications, which are hindered by the phenomenon known as ferroelectric fatigue that leads to the degradation of ferroelectric properties with polarization cycling. Multiple microscopic models explaining fatigue have been suggested; however, the chemical origins remain poorly understood. Here, we utilize multimodal chemical imaging that combines atomic force microscopy with time-of-flight secondary mass spectrometry to explore the chemical phenomena associated with fatigue in PbZr 0.2 Ti 0.8 O 3 (PZT) thin films. Investigations reveal that the degradation of ferroelectric properties is correlated with a local chemical change and migration of electrode ions into the PZT structure. Density functional theory simulations support the experimental results and demonstrate stable doping of the thin surface PZT layer with copper ions, leading to a decrease in the spontaneous polarization. Overall, the performed research allows for the observation and understanding of the chemical phenomena associated with polarization cycling and their effects on ferroelectric functionality.

Self‐Assembled Room Temperature Multiferroic BiFeO3‐LiFe5O8 Nanocomposites

“…The chemical sensitivity of SIMS allows the detection of the ion distribution on the surface of the sample with a spatial resolution of ~120 nm. [47,48] Figure 5a demonstrates an averaged mass spectrum with all the base elements Bi + , Fe + , and Li + present. The distribution of the corresponding peak area as a function of spatial location allows characterization of local chemical changes in the studied area.…”

Recent Progress in the Nanoscale Evaluation of Piezoelectric and Ferroelectric Properties via Scanning Probe Microscopy

“…[93] Figure 4d shows the representative PFM hysteresis loop as a function of the number of switching cycles measured in the PZT nanocapacitors. [131] As shown in the figure, the hysteresis loop clearly shows a rectangular shape, indicating ferroelectric polarization switching. This hysteresis loop measurement can be further extended for exploring spatially varying local switching behaviors based on grid-type measurements (i.e., spectroscopy), such as switching spectroscopy-PFM (SS-PFM), [130,[132][133][134][135] SS-PFM based on the first-order reversal curve (FORC) waveform, referred to as FORC-SS-PFM, [20,133] and switching dynamics spectroscopy-PFM.…”

“…For instance, SPM-based techniques could be combined with other chemical microscopic tools to facilitate both the physical and chemical understanding of nanoferroic phenomena. [131,178] Further, multiple SPM-based techniques could be combined for evaluating piezoelectric and ferroelectric properties accurately. We anticipate that, based on this progress, SPM can become a comprehensive platform for the evaluation of piezoelectric and ferroelectric properties at the nanoscale.…”

“…Figure (d) was reproduced with permission. [131] Copyright 2019, Springer Customer Service Center GmbH: Springer Nature. e,f) PFM phase and topography images of a typical MAPbI 3 sample surface, respectively.…”

Investigation of AFM-based machining of ferroelectric thin films at the nanoscale

“…Although in this case only the top electrodes are isolated while the bottom LaSrMnO 3 electrode is shared, similar to the terminology described in previous works where similar structures were fabricated, we describe the resulting nanoarray as a nanocapacitor array. 74,75 The topography of the fabricated nanocapacitor array is shown in Figure 5(c). It can be seen that the top electrodes on some of the islands have de-laminated, possibly due to poor adhesion.…”