Active Electrode Redox Reactions and Device Behavior in ECM Type Resistive Switching Memories

Electrochemical metallization cells rely on oxidation, reduction, and migration of metal cations in nanoscale thin films. The cations are typically provided by the oxidation of the active electrode. Commonly, Cu, Ag, or their compounds are used as electrodes for injecting cations into solid electrolytes, such as Ta2O5 or SiO2. However, the used criteria are mainly based on empirical knowledge. In this work, different materials (Ag, Al, Au, Cu, Fe, Ni, Ta, Ti, V, and Zr) are investigated for active electrodes and their redox reactions are studied. It is found that the electrochemical behavior of the metals is crucial for the switching properties, as well as for filament stability and retention properties of the devices. The Gibbs free energy of formation of the cations is identified as crucial factor for selection criteria.