Direct Observations of Nanofilament Evolution in Switching Processes in HfO2 -Based Resistive Random Access Memory by In Situ TEM Studies.

Resistive switching processes in HfO2 are studied by electron holography and in situ energy-filtered imaging. The results show that oxygen vacancies are gradually generated in the oxide layer under ramped electrical bias, and finally form several conductive channels connecting the two electrodes. It also shows that the switching process occurs at the top interface of the hafnia layer.