First direct observation of the built-in electric field and oxygen vacancy migration in ferroelectric Hf_0.5Zr_0.5O₂ film during electrical cycling

By combining differential phase contrast scanning transmission electron microscope (DPC-STEM) and Energy Disperse Spectroscopy (EDS) analysis, the migration of oxygen vacancies and the evolution of the built-in field in ferroelectric HfO2 are observed for the first time.