Determining the Relationship Between Composition, Structure, and Device Properties of Ge x Se 1‐x ‐Based Selector‐Only Memory

ABSTRACT Selector‐only memory (SOM) is an emerging device for Compute Express Link (CXL)‐based memory systems, combining intrinsic selector functionality with memory operation to enable low‐power switching, structural simplicity, and high‐density 3D crossbar integration. To fully exploit its potential as a scalable and energy‐efficient memory platform, a fundamental understanding of its physical mechanism and active layer engineering is essential. Here, we systematically investigate the composition‐dependent structural, bonding, and electronic properties of amorphous Ge x Se 1‐x through first‐principles calculations and correlate them with experimentally measured device characteristics. Increasing Ge concentration strengthens Ge─Se bond covalency and network rigidity, suppressing atomic movement and changes of local dipoles under external electric field. These atomistic changes closely correlate with macroscopic device performance: Ge‐rich compositions exhibit enhanced endurance but reduced memory window, revealing an intrinsic trade‐off between switching stability and threshold voltage separation. Furthermore, band gap narrowing with increasing Ge content lowers the threshold voltage while increasing off current. Our results suggest that field‐induced atomic rearrangement and change in short‐range ordering form a primary underlying mechanism of SOM. Finally, by mapping the structural and electronic dependencies of the amorphous matrix to the observed device behavior, this work offers insight for engineering reliable, high‐density memory devices suitable for next‐generation CXL‐based architectures.