Low voltage two-state-variable memristor model of vacancy-drift resistive switches

We illustrate a heuristic two-state-variable memristor model of charged O vacancy-drift resistive switches that include the effects of internal Joule heating on both the electronic transport and the drift velocity (i.e., switching speed) of vacancies in the switching material. The dynamical state variables correspond to the cross-sectional area of a conducting channel in the device and the gap between the end of the channel and one of the electrodes. The model was calibrated against low voltage pulse-sweep and state-test data collected from a TaOx memristor so that the contributions of the channel gap, area and temperature to switching can be analyzed. The model agrees well with experimental results for long switching times and low-to-intermediate voltage operation.