Impact of the temperature on the conductive filament morphology in HfO2-based RRAM

In this letter, we study the impact of the temperature on the resistive switching effect of TiN/Ti/HfO2/W metal–insulator-metal devices. An analysis of the conduction mechanisms is made, with the low resistance state being ruled by nearest neighbor hopping, while the conduction in the high resistance state is dominated by Schottky emission. Taking into account the filamentary mechanism behind the resistive switching effect, a thorough analysis of the Schottky emission allows for the calculation of the gap between conductive filament tip and metal electrode in the high resistance state. We report an increase of this gap when temperature lowers below a certain value. Moreover, the mentioned gap adopts values of integer multiples of the the mean distance between traps obtained by the hopping model.