Resistive Switching by Voltage-Driven Ion Migration in Bipolar RRAM—Part I: Experimental Study

Resistive-switching random access memory (RRAM) based on the formation and the dissolution of a conductive filament (CF) through insulating materials, e.g., transition metal oxides, may find applications as novel memory and logic devices. Understanding the resistive-switching mechanism is essential for predicting and controlling the scaling and reliability performances of the RRAM. This paper addresses the set/reset characteristics of RRAM devices based on $\hbox {HfO}_{x}$ . The set process is analyzed as a function of the initial high-resistance state and of the current compliance. The reset process is studied as a function of the initial low-resistance state. Finally, the intermediate set states, obtained by set at variable compliance current, and reset states, obtained by reset at variable stopping voltage, are characterized with respect to their reset voltage, allowing for a microscopic interpretation of intermediate states in terms of different filament morphologies.