Nitrogen-Induced Filament Confinement Technique for a Highly Reliable Hafnium-Based Electrochemical Metallization Threshold Switch and Its Application to Flexible Logic Circuits

Electrochemical metallization (ECM) threshold switches are in great demand for various applications such as next-generation logic technology, future memory, and neuromorphic computing. However, the instability of operation due to inherent filamentary randomness is a severe problem that is yet to be solved. Here, we propose a specially treated hafnium oxide (HfO _x :N)-based ECM threshold switch with high reliability, low-voltage operation (0.2 V), high ON/OFF ratio (5 × 10 ⁸ ), great endurance (10 ⁶ ), and fast switching speed (1.5 μs at 2 V). The nitrogen ions in the HfO _x :N layer assist confining the path of the metallic filament, which significantly suppresses filament randomness as well as reduces power consumption and alternating current response time. The feasibility of ECM threshold switches to logic applications, AND and OR, is first introduced. The ECM threshold switch has great potential to be utilized in complementary logic circuits because of its ultralow operation power consumption, high integrability using an array structure (4F ² ), and fast switching characteristics. Furthermore, we have successfully verified its applicability to flexible electronics on polyethylene naphthalate films that can retain stable operation under considerable mechanical stress. We believe that this research paves the way to fabricate highly reliable ECM threshold switches for flexible complementary logic circuits with ultralow power consumption.