Oxygen migration process in the interfaces during bipolar resistance switching behavior of WO _3-x-based nanoionics devices

Bipolar resistance switching (BRS) behavior and the effects of atmosphere (air, vacuum, O ₂ gas, or N ₂ gas) on BRS behavior occurred in the top and bottom interfaces in the M _{(top electrode)}/WO _3-x/Pt _{(bottom electrode)} (M Pt, Au) devices were investigated. Stable BRS only can be obtained in the interface with Pt electrode. And, the top Pt/WO _3-x interface exhibited stable BRS only in an oxygen-rich atmosphere (air and O ₂ gas). In contrast, the bottom WO _3-x/Pt interface showed stable BRS under any atmosphere. Based on the x-ray photoelectron spectroscopy measurement on Pt, Au/WO _3-x interfaces, it is identified that the oxygen migration process during resistance switching mainly occurs between the Pt/WO _3-x interface and Pt electrode.