fig13
Figure 13. (A) STEM-HAADF images of HfO2 films at pristine, wake-up and fatigue stages, showing phase transformation and corresponding phase fractions at different stages[33]. (B) Proposed physical mechanism behind the field-induced FE behavior by coupling with phase transformation, defect generation and diffusion, and charge injection[25]. STEM-HAADF: Scanning transmission electron microscopy-high angle annular dark-field; FE: ferroelectric.
