Enabling Memory Window in Ovonic Threshold Switch Devices Through Cu-Based Trap for Selector-Only Memory Operation

In this study, we propose a method to generate a memory window enabling the ovonic threshold switch (OTS) operate as a selector-only memory(SOM) by doping Cu. Unlike conventional approaches that rely on internal modifications within the device, our method controls trap formation through the supply and migration of Cu via an external Cu electrode. To prevent the excessive supply of cations, which could lead to Cu conducting filament formation, we employed a series resistance and a C diffusion barrier. To demonstrate that the operation mechanism of this device is not based on Cu filamentary switching, we presented the bipolar switching behavior. We also identified a relationship among the memory window, leakage current, and retention, which varies depending on the write current. Furthermore, we analyzed changes in the trap density and activation energy to explain the threshold voltage variation caused by the traps. This work provides a pathway for OTS devices, previously incapable of achieving a memory window, to operate as SOM.