Filament Growth and Resistive Switching in Hafnium Oxide Memristive Devices.

We report on the resistive switching in TiN/Ti/HfO/TiN memristive devices. A resistive switching model for the device is proposed, taking into account important experimental and theoretical findings. The proposed switching model is validated using 2D and 3D kinetic Monte Carlo simulation models. The models are consistently coupled to the electric field and different current transport mechanisms such as direct tunneling, trap-assisted tunneling, ohmic transport, and transport through a quantum point contact have been considered. We find that the numerical results are in excellent agreement with experimentally obtained data. Important device parameters, which are difficult or impossible to measure in experiments, are calculated. This includes the shape of the conductive filament, width of filament constriction, current density, and temperature distribution. To obtain insights in the operation of the device, consecutive cycles have been simulated. Furthermore, the switching kinetics for the forming and set process for different applied voltages is investigated. Finally, the influence of an annealing process on the filament growth, especially on the filament growth direction, is discussed.