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, Cu_2-alphaS, with Ta₂O₅, which enabled us to appropriately adjust V _ON with a smaller Cu⁺ ion diffusion coefficient.