Dynamics of set and reset processes in HfO2 -based bipolar resistive switching devices

Abstract

The temporal evolution of the set and reset processes in TiN/Ti/HfO2/W metal-insulator-metal devices exhibiting resistive switching behavior is investigated in depth. To this end, current transients were recorded by applying different voltages, which allowed us to change the conductance of the device. While both set and reset transitions are faster with increasing applied voltage, they clearly exhibit different time responses. The set transition is characterized by a monotonic increase in current after a sudden initial rise in its value, while the reset transition is characterized by a notably nonlinear response that resembles a sigmoidal function. We have successfully modeled the reset current transient with a bi-dose function and defined its time constant (Time-to-Reset) as the time where the current variation reaches its maximum value. Our findings show that varying the initial conditions of the reset process, such as increasing the temperature and/or decreasing the initial resistance value, significantly affect the reset transient, exponentially increasing the reset time constant value. This allows us to model its dependencies with the equation of a plane.