Nitrogen-Doped GeTeS Ovonic Threshold Switching Selector With Optimized Performance Trade-Off for 1S-1R Phase-Change...

Ovonic threshold switching (OTS) selector devices are critical for suppressing sneak-path leakage current and ensuring cell selectivity in high-density crosspoint memory arrays, while enabling nanosecond-scale switching and low-power operation. However, amorphous chalcogenide-based OTS selectors face challenges including limited durability, poor thermal stability, and an inherent trade-off between switching speed and threshold voltage (V_th). To address these issues, this study proposes a Ge-Te-S (GeTeS) mixed composition fabricated by co-sputtering Te and S, combining the fast switching and low V_th of GeTe with the high durability and thermal stability of GeS. Nitrogen-doped GeTeS (N-GeTeS) was then developed by incorporating nitrogen into the GeTeS matrix. Nitrogen doping suppresses unstable bonds via strong S─N bond formation, reduces trap density, improves V_th uniformity, and widens the band gap to reduce off-current. The resulting N-GeTeS OTS device demonstrates excellent durability (≈10¹⁰ cycles), high crystallization temperature (≈470°C), fast switching speed (≈18 ns), low V_th (≈1.5 V), low leakage current (≈2.8 × 10^-9 A), and a high on/off ratio (≈3×10⁵). In a one-selector- one-resistor configuration integrated with phase-change memory, the N-GeTeS selector enables stable memory cell operation through threshold voltage-controlled current blocking. Overall, N-GeTeS shows strong potential for scalable, high-density memory array applications.