Nanoionic transport and electrochemical reactions in resistively switching silicon dioxide

Abstract

The mobility of copper ions and redox reactions of Cu at the interface with SiO₂ being directly attributed to the resistive switching effect have been studied by cyclic voltammetry (CV). The electrode kinetics of the Cu^z+/Cu redox reactions were analyzed suggesting the formation of both Cu⁺ and Cu²⁺ species. The ion mobility shows an unexpected strong dependence on the ion concentration indicating ion–ion interactions typical for concentrated solution conditions. Based on the standard reduction potentials for Cu^z+/Cu we identified partial electrochemical redox reactions during oxidation and reduction. The results contribute to a detailed understanding of the resistive switching effect in Cu/SiO₂/Pt cells and provide insight into electrochemically assisted diffusion of metal cations in oxides in general.