Improved switching characteristics of an atomic switch device by highly restricted Ag doping

An atomic switch (AS) device is a nanoionic switching device that operates through the electrochemical migration of metal ions and the subsequent formation or dissolution of metallic filaments within an electrolyte. Volatile AS devices are potential candidates as selector devices in cross-point array memory architecture. In this study, we improved the switching characteristics of an AS device by severely restricting Ag doping into the HfO₂electrolyte. Using a collimated sputtering process, we precisely controlled the amount of Ag doped in the electrolyte, and Ag doped AS device (W/HfO₂:Ag/Pt) exhibits a higher threshold voltage (V_th) and enhanced turn-off speed compared with conventional AS devices (Ag/HfO₂/Pt). To understand the origin of these improvements, we analyzed both Ag-doped AS device and a conventional AS device with the framework of field-induced nucleation theory. Both devices showed an exponential relationship between delay time and voltage, but with different values of nucleation barrier energies (W₀); the Ag-doped AS device exhibited a significantly higherW₀. These results indicate that limit restricting Ag doping increases the nucleation barrier energy, leading to less stable filaments and thereby improving switching characteristics.