Combinatorial Synthesis of Cu/(Ta x Nb1–x )2O5 Stack Structure for Nanoionics-Type ReRAM Device

Resistive random access memory (ReRAM) has been proposed as a new application for oxide materials. We have proposed a Cu electrode/dielectric oxide/bottom electrode stack structure as a potential ReRAM material that is compatible with the LSI process. Control of the switching voltage and the initial conductive filament formation process is beneficial for actual applications. To control the switching property by controlling the valence state of metals, we investigated the Ta–Nb binary oxide ((Ta x Nb1–x )2O5) system as a dielectric oxide layer using a combinatorial method. A combinatorial pulsed laser deposition method was used to fabricate the (Ta x Nb1–x )2O5 system systematically on a Pt/Si substrate. X-ray photoelectron spectroscopy revealed defect formation relating to Ta and the compensation of oxygen vacancies caused by a change in the valence number of Nb. As the Ta content decreased, there were a decrease in the threshold voltage of the low resistive state and an enhancement of the leakage current, meaning that the switching properties can be controlled by controlling the (Ta x Nb1–x )2O5 system.