Diffusivity of Cu Ions in Solid Electrolyte and Its Effect on the Performance of Nanometer-Scale Switch

A novel solid-electrolyte nonvolatile switch that we previously developed for programmable large-scale-integration circuits turns on or off when a conducting Cu bridge is formed or dissolved in the solid electrolyte. Cu+ ion migration and an electrochemical reaction are involved in the switching process. For logic applications, we need to adjust its turn-on voltage (V-ON), which was too small to maintain the conductance state during logic operations. In this paper, we clarified that V-ON is mainly affected by the rate of Cu+ ion migration in the solid electrolyte. Considering the relationship between the migration rate and V-ON, we replaced the former electrolyte, Cu2-alpha S, with Ta2O5, which enabled us to appropriately adjust V-ON with a smaller Cu+ ion diffusion coefficient.