Rate-limiting processes determining the switching time in a Ag₂S atomic switch

The switching time of a Ag₂S atomic switch, in which formation and annihilation of a Ag atomic bridge is controlled by a solid-electrochemical reaction in a nanogap between two electrodes, is investigated as a function of bias voltage and temperature. Increasing the bias voltage decreases the switching time exponentially, with a greater exponent for the lower range of bias than that for the higher range. Furthermore, the switching time shortens exponentially with raising temperature, following the Arrhenius relation with activation energy values of 0.58 and 1.32 eV for lower and higher bias ranges, respectively. These results indicate that there are two main processes which govern the rate of switching, first, the electrochemical reduction Ag ⁺+e^-→Ag and, second, the diffusion of Ag⁺ ions. This investigation advances the fundamental understanding of the switching mechanism of the atomic switch, which is essential for its successful device application.