Wake-up effect in Hf_0.4Zr_0.6O₂ ferroelectric thin-film capacitors under a cycling electric field

We examined the wake-up effect in a TiN/Hf_0.4Zr_0.6O₂/TiN structure. The increased polarization was affected by the cumulative duration of a switched electric field and the single application time of the field during each switching cycle. The space-charge-limited current was stable, indicating that the trap density did not change during the wake-up. The effective charge density in the space-charge region was extracted from capacitance-voltage curves, which demonstrated an increase in free charges at the interface. Based on changing characteristics in these properties, the wake-up effect can be attributed to the redistribution of oxygen vacancies under the electric field.