Modeling of switching speed and retention time in volatile resistive switching memory by ionic drift and diffusion

The understanding of the dynamic mechanism of volatile resistive switching memory devices is of paramount importance to further increase the switching speed. It is also of great value for future neuromorphic applications which use such devices in temporal domain. In this work, we investigate the switching speed and retention time of metallic filamentary volatile resistive switching devices. We find that the switching speed can be quantitatively described by the ionic mobility, while the retention time can be quantitatively described by the surface ionic diffusion following the gradient descent of surface atomic concentration. Further analysis reveals that the ionic mobility and surface diffusivity can be connected with Einstein relation. Finally, evidences supporting this relation and experimental data showing the competition of the ionic drift and diffusion are collected and shown.