First principles study of oxygen vacancy activation energy barrier in zirconia-based resistive memory.

Unlike experimental measurements that appeared to be quite large activation barriers, oxygen vacancies in zirconia-based resistive random access memory (ReRAM) are believed to migrate with a fairly low energy barrier, and this discrepancy has not been noticed nor seriously questioned up to date. In this paper, we work on this problem by means of first-principles calculations categorizing all the possible migration pathways by crystallographic directions. From the results, it is found that the low activation energy of oxygen vacancy that is expected from the switching characteristic of the device is originated from +2q charged oxygen vacancies in a nanometer-sized filament migrating into a particular crystallographic direction of monoclinic zirconia.