Coexistence of Nonvolatile WORM, Bipolar, Unipolar, and Volatile Resistive Switching Characteristics in a Dry Oxide Layer With Ag Conductive Bridges

In this study, we demonstrate multimemory functions of anAg/SiO _x /n ⁺ -Si device, including nonvolatile (NV) write-once-read-many-times (WORM), NV bipolar, NV unipolar, and volatile resistive switching (RS) characteristics. The SiO _x layer is grown using a dry oxidation process. Different RS features are obtained by modulating the compliance current during device operation. The resistance switch from the OFF to ON state, corresponding to a set process, is observed in the positive voltage region, which indicates that the Ag cations are responsible for the RS process. When the Ag/SiO _x /n ⁺ -Si memory switches to the ON state, an Ag conductive bridge (CB) in the SiO _x layer is indeed observed under transmission electron microscopy (TEM) examination. A CB-based model is used to explain the different RS behaviors of the Ag/SiO _x /n ⁺ -Si resistive memory.