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ABSTRACT
Pt/SrBi2Ta2O9(SBT)/Pt ferroelectric capacitors with the film thickness of 300 nm were successfully fabricated using metalorganic decomposition (MOD) technique. The fatigue and imprint behaviors were studied. It is found that the switchable polarization of SBT capacitors had the increasing trend in the first stage, and after 2× 109 switching cycles, the switchable polarization began to decrease. The domains in SBT thin films were weakly pinned by defect charges and they were easily depinned when applying an external field, which resulted in the increase of switchable polarization. Furthermore, the depinned defect charges moved to the electrode interfaces and aggregated there, then resulted in the polarization suppression at last. During the switching process, both the behavior of fatigue and imprint existed simultaneously. A competition relationship existed between the depinning behavior of domains and the aggregation of defect charges at the electrode interfaces. It was the competition that decided the fatigue characterization for SBT capacitors. The higher the external voltage, the more suppressed polarization could be recovered, which suggested that more domains in SBT thin films were easily depinned under a higher external field, and the pinning depth by defect charges was different.
ACKNOWLEDGMENTS
The authors are grateful for the financial support from National Natural Science Foundation of China (90407023), and “863” Program of China (2004AA404240).