Te-composition and programming-scheme dependence of electrical characteristics in Ge 2 Se 3 Te x selector-only memory devices

Abstract As the digital society expands rapidly, the demand for large-scale data storage and processing continues to grow, which increases the importance of nonvolatile memory technologies capable of operating in highly integrated arrays. Selector-only memory (SOM) has recently attracted attention as a promising concept because it enables programmable threshold-voltage state separation using a single amorphous chalcogenide-based ovonic threshold switch device, leading to simplified processing and improved integration density. In this study, we systematically investigated how the Te content in Ge 2 Se 3 Te x ( x = 2, 3, 4, 5) affects the SOM memory window (MW) and reliability characteristics. SOM operation was observed for all compositions under both bipolar programming and fall-time-controlled unipolar programming; however, the optimal composition for the maximum MW depended on the operating scheme. In reliability tests, endurance tended to be superior for Te-rich compositions, whereas thermal retention at 85 °C improved for Te-poor compositions, revealing a clear trade-off. Trap-assisted hopping model fitting showed that state separation is primarily correlated with the activation energy difference, while changes in the trap-to-trap distance were limited. These results demonstrate the potential of Ge–Se–Te materials as SOM active layers and clarify Te-content-dependent performance–reliability trade-offs and limitations. This work is expected to serve as a practical basis for optimizing the balance between performance and reliability in SOM devices through future compositional and doping designs.