Impedance Spectroscopy Characterization in Bipolar Ta / MnO x / Pt Resistive Switching Thin Films

Impedance spectroscopy was applied to MnO x ‐based thin films prepared in symmetric and asymmetric electrode configurations, i.e., Pt / MnO x / Pt and Ta / MnO x / Pt , respectively. Equivalent circuit analysis suggests the presence of higher resistance surface layers adjacent the electrodes, in addition to a higher conductivity component at central portions of the MnO x thin films. The asymmetric configuration enables the Ta / MnO x interfacial layer to facilitate the redox transport of oxygen ions, where significant changes in resistance with the electric field are responsible for the higher on/off resistance ratio in Ta / MnO x / Pt . The higher dielectric constant and bias‐dependent capacitance and resistance support the coexistence of both oxidized surfaces and interfacial layers.