Semiconducting-like filament formation in TiN/HfO2/TiN resistive switching random access memories

The conduction mechanisms and nature of the filament formed in the low resistive state of TiN/HfO2/TiN resistive random access memories are studied from the temperature-dependence of their current-voltage characteristics. These characteristics are analyzed using the percolation theory of conductor networks, allowing us to extract the temperature-dependence of their effective resistivity. The results suggest a semiconducting-like nature of the filament in these devices. By considering the formation of a large density (about 10 at. %) of oxygen vacancies in HfO2, the electronic properties of such O-deficient HfOx filaments are computed using first-principles calculations. These calculations confirm the likely semiconducting nature of the filament formed in these devices.