抄録
Bi-based ferroelectric materials are regarded as potential materials for nonvolatile ferroelectric memories due to their good fatigue property and high leakage resistance. For the high-speed memory application, it is essential to understand the polarization switching in the film at high frequency. However, the frequncy dependence of polarization swithing is still lack of understanding at present. In this study, we used a wide gain-bandwidth intergration circuit to measure the polarization hysteresis and studied its frequency dependence. We revealed that the hysteresis of SrBi2Ta2O9 film was frequency dependent. In the frequency range from 10 Hz to 800 kHz, the maximum polarizations decreased logarithmically as increasing the frequency. In contrast, the coercive field increased with the frequency increase. From the frequency dependence of coercive field, it seems that two kinds of mechanisms contributed to the switching. They crossovered around 100 kHz, below which the coercive field did not decrease as the conventional prediction.
