The effect of crystallinity of HfO2 on the resistive memory switching reliability

We measured direct physical evidence that can explain different switching behaviors for HfO₂ based ReRAM structure for the first time. The switching behavior depends on the degree of crystallinity of HfO₂. We observed crystallized HfO₂ which is grown under higher temperature with High Resolution Scanning Transmission Electron Microscopy (STEM) Electron Energy Loss Spectroscopy (EELS), which prevents creating enough oxygen vacancies to start electric switching under low forming voltage. However, non-stoichiometric structure region of HfO₂ which has amorphous phase provides enough oxygen vacancies which are the electrical paths. Therefore, non-stoichiometric structure of amorphous HfO₂ during fabricating process is crucial to obtain reliable switching characteristics.