Switching Control of Oxide-Based Resistive Random-Access Memory by Valence State Control of Oxide

Abstract

Controlling the switching voltage and initial conductive filament formation of resistive random-access memory (ReRAM) is beneficial for actual applications. As summarized in Chap. 4, the density of oxygen vacancies is important in terms of controlling the conductive filament formation and switching of a nanoionic-type ReRAM structure. In this chapter, as an example of the control of oxygen vacancies and switching properties of the ReRAM structure, the intentional change in the valence state of an oxide layer is described. We investigated the Ta-Nb binary oxide ((Ta_xNb_1-x)₂O₅) system as a dielectric oxide layer by a combinatorial method. A combinatorial pulsed laser deposition method was used to fabricate the (Ta_xNb_1-x)₂O₅ system systematically. X-ray photoelectron spectroscopy revealed defect formation relating to Ta and the compensation of oxygen vacancies caused by a change in the valence of Nb. As the Ta content decreased, a decrease in the threshold voltage of the low-resistance state and an enhancement of the leakage current were observed, meaning that the switching properties can be controlled by controlling the (Ta_xNb_1-x)₂O₅ system.