Unipolar and bipolar fatigue in antiferroelectric lead zirconate thin films and evidences for switching-induced charge injection inducing fatigue

Abstract

We show that unipolar fatigue does occur in antiferroelectric capacitors, confirming the predictions of a previous work ͓Appl. Phys. Lett. 94, 072901 ͑2009͔͒. We also show that unipolar fatigue in antiferroelectrics is less severe than bipolar fatigue if the driving field is of the same magnitude. This phenomenon has been attributed to the switching-induced charge injection, the main cause for polarization fatigue in ferroelectric and antiferroelectric materials. Other evidences for polarization fatigue caused by the switching-induced charge injection from the nearby electrode rather than the charge injection during the stable/quasistable leakage current stage are also discussed.Recently, antiferroelectric materials have attracted much research interest due to their potential applications in microactuators and energy conversion devices. 1 Antiferroelectrics show characteristic double hysteresis loop upon the application of an ac external field, different from the well known single loop shown by ferroelectrics. However, like ferroelectric materials antiferroelectrics also show polarization fatigue under repetitive bipolar electrical cycling, which has been one of the main obstacles for the development of electronic devices made from these materials.For many years, polarization fatigue also represents one of the most serious difficulties for realizing nonvolatile ferroelectric random access memories, 2,3 along with imprint, 2 polarization retention, 4,5 and electrical breakdown. 6,7 Although polarization fatigue in ferroelectric materials has been extensively studied during the last few decades, that in antiferroelectrics has not. Furthermore, the very limited publications on fatigue in antiferroelectric capacitors are all concentrated on bipolar fatigue and surprisingly enough there is no work on unipolar fatigue in antiferroelectric materials.Recently, we have built a fatigue theory for ferroelectric materials, which emphasizes the extremely high depolarization field generated near the electrode-film interface by the polarization charges at the tip of the needlelike domains during switching ͑therefore we called it the LPD-SICI model; LPD-SICI denotes local phase decomposition caused by switching-induced charge injection͒. 3,8,9 This model has been subsequently generalized to describe the fatigue problem in antiferroelectrics. 10 In particular, this model explains why polarization fatigue in antiferroelectric materials is much less severe than that in ferroelectrics under similar or even more severe bipolar electrical cycling as observed in the literature. 10-13 Moreover, this model indicates that antiferroelectric materials should show observable fatigue under unipolar electrical cycling, which has not been confirmed yet so far due to the lack of experimental data in the literature as mentioned above. In this work, we show unambiguously that both bipolar fatigue and unipolar fatigue occur in antiferroelectric lead zirconate ͑PZO͒ thin films with the latter being less severe than the former under cycling field of ...

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“…driving voltage amplitudes, respectively. One can see the suppression of dielectric constant and the enhancement in dielectric loss versus cycling number N is in line with those reported in the literature [22][23][24]. In addition, it is shown that the dielectric constant decreases while the tangent loss increases with increasing the pulse width and driving voltage.…”

Giant Negative Electrocaloric Effect in Antiferroelectric La‐Doped Pb(ZrTi)O3 Thin Films Near Room Temperature

“…Nevertheless, further discussions of any thermodynamic cycles of negative EC devices based on AFE thin fi lms are beyond the scope of this study, we suggest that direct measurements should fi rst be made in the future to confi rm our indirect measurements here. High EC resistance is expected especially under unipolar electrical cycling, [ 26,36 ] which is also desirable for the design of EC devices. In addition, Joule heating can be negligible, as shown by the leakage current data ( Figure S4, Supporting Information).…”

Decoding the Fingerprint of Ferroelectric Loops: Comprehension of the Material Properties and Structures

“…The microcracks actually pin the domain wall motion, resulting in the lower switchable polarization. By comparing with bipolar and unipolar fatigue processes, Lou and Wang suggested a scenario that polarization fatigue is mainly caused by the switching induced charge injection other than the charge injection during the stable/quasi‐stable leakage stage …”