GeSeTe for Enhanced Thermal Stability and Reliability in Ovonic Threshold Switching Materials

Ovonic threshold switching (OTS) selectors have become essential components in high-density memory architectures, particularly in 3D stackable memory and selector-only memory (SOM) technologies. Nevertheless, their practical application is often constrained by inherent challenges in thermal stability and operational reliability. In this work, we present a systematic study on GeSeTe-based OTS selectors with strategically modulated Ge content. These devices demonstrate remarkable characteristics, including ultralow leakage current (∼10^-9 A), nanosecond-scale switching speed (∼10 ns), and endurance exceeding 10⁸ cycles─even after high-temperature annealing at 400 °C. The enhanced comprehensive performance stems from the reinforced covalent bonding network resulting from higher Ge content, while excessive Ge leads to increased structural rigidity and the introduction of metastable defects. Additionally, the fabricated GeSeTe-based SOM cells achieve stable switching operations with a 0.9 V memory window, and we further reveal the phenomenon of electric-field-driven atomic segregation, which elucidates the underlying mechanism of the polarity-dependent switching behavior. These insights establish Ge content engineering as a critical pathway for the design of high-performance, thermally robust OTS selectors and next-generation SOM devices.