Fig. 1. Schematic diagram of triangular pulse shapes used for hysteresis loop measurements. E, T, and f mean the electric field, pulse period, and its corresponding frequency, respectively.
Fig. 2. Surface morphology of ferroelectric film measured with AFM. The measurement were performed by tapping mode in the area of 1 μm × 1 μm (256 × 256 pixels) using NanoMan of Vecco Instruments, Inc.
Fig. 3. Displacement-electric field (D-E) hysteresis loops for different thickness values. The unit of thickness is nanometer. EMAX, T and f are 1.33 MV/cm, 16 ms and 62 Hz, respectively.
Fig. 4. Relationships between remanent polarization and film thickness.
Fig. 5. Coercive voltage-frequency relationships for different EMAX values. The film thickness is 90 nm.
Fig. 6. Coercive voltage-frequency relationships for different thickness and EMAX values. For each thickness, three kinds of EMAX values were used except the case of 120 nm. Frequency range is from 25 Hz to 260 Hz.
Fig. 7. Coercive field-frequency relationships for different thickness and EMAX values. For each thickness, three kinds of EMAX values were used except the case of 120 nm. Frequency range is from 25 Hz to 260 Hz.
Table 1. Fitting parameters extracted from coercive voltage-frequency relationships
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