Switching Characteristics of $\hbox{Ru/HfO}_{2} \hbox{/TiO}_{2-x}\hbox{/Ru}$ RRAM Devices for Digital and Analog Nonvolatile Memory Applications

Abstract

We report the switching characteristics of RRAM devices consisting of Ru/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-x</sub> /Ru stacks with and without an external access device. In addition to bistable switching, we also achieved an analog reconfiguration of resistance by controlling the compliance current or the reset voltage to achieve a low-resistance state (LRS) or a high-resistance state (HRS), respectively. All intermediate states were nonvolatile in nature. The transport studies using temperature-dependent <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> measurement indicated the mechanism of conduction to be ionic in LRS and Frenkel-Poole in both HRS and virgin resistance state of a device.