Understanding of the Volatile and Nonvolatile Switching in Ag-Based Memristors

Memristors, possessing volatile and nonvolatile switching characteristics, exhibit great potential for high-density data storage and neuromorphic computing system. However, the adjustment of device electrical characteristics, such as drive current and threshold voltage, is still not specific, which hinders the optimization of memristors for desired applications. In this work, we fabricated Ag-based memristive devices with different stoichiometries and density of silicon suboxide (SiO _x ) dielectric layers, which can both exhibit volatile and nonvolatile switching behaviors and the volatile and nonvolatile switching can transfer each other by varying the compliance current. The experimental results showed that high stoichiometry of SiO _x film will lead to high compliance current for the transition from volatile to nonvolatile characteristics in Ag-based memristors. A model based on classical nucleation theory (CNT) was proposed to explain the transition current of different samples. It was found that the volatile and nonvolatile switching behaviors had a close correlation with the surface energy of conductive filament and defects in the dielectric layer. Besides, the dielectric layer of memristors deposited under low RF power exhibited large density, which caused large threshold voltage during the set process. This work provides the adjustment methods of drive current and threshold voltage from material properties.