High-Thermal-Stability Ovonic Threshold Switch Based on Silicon-Doped GeS

Sulfur-based chalcogenides have emerged as the third material class for ovonic threshold switch (OTS), however, representative material, GeS, still struggles to withstand back-end-of-line (BEOL) process. Here we systematically investigate the impact of Si doping on the thermal stability and electrical performance of GeS-based OTS devices. Si incorporation raises the crystallization temperature of GeS above 400°C, suppresses voltage drift to 26 mV/dec, enhances switching window consistency, and reduces the leakage current ( ${I}_{\mathbf {\text {of}\text {f}}}$ ) below 10nA. The improved thermal stability arises from increased amorphous disorder induced by higher Si doping. When the Si content is $\le 6$ at.%, a rise in trap density leads to increased threshold voltage ( $V_{\mathbf {\text {th}}}$ ) and reduced ${I}_{\mathbf {\text {of}\text {f}}}$ . In contrast, excessive Si doping causes supersaturation and precipitation of Si atoms, which narrows the bandgap and lowers the trap density, ultimately resulting in a decreased $V_{\mathbf {\text {th}}}$ and increased ${I}_{\mathbf {\text {of}\text {f}}}$ .