Critical Analysis of Thermodiffusion‐Induced Unipolar Resistive Switching in a Metal‐Oxide‐Metal Memristive Device

Abstract

It has been previously proposed that the SET and RESET processes in a unipolar switching metal‐oxide‐metal memristive device can be explained by thermodiffusion only. In order to validate this, time‐dependent finite element method simulations are performed in a purely theoretical study. To that end, a range of configurations regarding device geometry and various parameters is used. In particular, this includes simulations using different activation enthalpies for oxygen vacancy transport, different radii for the top electrode, and different time constants for the applied voltage or current. When the top electrode is smaller than the other layers by a sufficient margin, a temperature gradient emerges that in turn leads to a transport of oxygen vacancies toward the center of the oxide. This effect can be interpreted as a SET. In a system with low activation enthalpy for vacancy transport, i.e., 0.4 eV or less, the effect is volatile, while it is nonvolatile for activation enthalpies of 0.9 eV or more. However, in the latter case, a RESET is not possible. Therefore, further effects other than thermodiffusion must be taken into account in the description of unipolar resistive switching.