Deep Insight into Steep‐Slope Threshold Switching with Record Selectivity (>4 × 10¹⁰) Controlled by Metal‐Ion Movement through Vacancy‐Induced‐Percolation Path: Quantum‐Level Control of Hybrid‐Filament

Abstract This study demonstrates a hyper‐level control of metal‐ion migration through vacancy‐induced‐percolation (VIP) path to maximize the steep‐slope performance of the threshold selector with excellent selectivity and endurance. Highly efficient control over metal‐ion migration through VIP is achieved with sophisticated stack engineering through the material evolution process and refined electrical operation. A thorough analysis of the energetics of metal‐ion‐ and vacancy‐based hybrid filament is performed using density functional theory calculations, which leads to a proper tuning of the biasing scheme. Command over bias‐induced ion migration to control the atomic‐scale filament is the key to maximize the threshold switching (TS) performance. The devices are designed with different diffusive materials and alloys. Precise atomic‐level control is realized with optimized device structure and alloy electrode, which indicates that the TS is safe within the vicinity of quantum contact. Owing to the synergistic impact of localized metal‐ion injection through VIP, alloy electrode material, and atomic‐level filament, the devices exhibit meticulous control of a highly stable TS with a high steep‐slope of <2 mV dec⁻¹, extremely high selectivity of >4 × 10¹⁰ with an exceptional endurance >10⁹ cycles, and device yield of 100%, which suggest the applicability of these devices in 1S1R and 1T1R platforms.