Threshold Switching Behavior and Underlying Mechanisms in Pure SiO₂-Based Selectors

In high-density crossbar array memory architectures, selector devices play a crucial role in suppressing sneak-path currents and ensuring stable operation. In this study, we propose a pure SiO2-based selector fabricated using conventional semiconductor processes and materials and experimentally demonstrate its threshold switching (TS) characteristics. Stable TS behavior is verified with an endurance exceeding 109 cycles under repeatable measurement sequences and pulse-driven operations. Interface structure analysis combined with controlled pulse-based electrical characterization reveals that the formation of oxygen vacancies (VOs), the resulting structural asymmetry, and the dynamic charging behavior of VOs within the oxide are the key mechanisms governing the TS manifestation. Based on these insights, the optimized pulse conditions are established for reliable TS operation. The proposed selector, featuring a simple undoped oxide structure, can be fabricated at temperatures below 300 °C and offers tunable threshold voltage, enabling excellent integration compatibility with advanced memory devices. This study introduces a selector structure that distinguishes itself from conventional chalcogenide- or metal-oxide-based selectors by combining superior process and device compatibility with structural simplicity, offering a promising pathway toward a highly integrated and CMOS-compatible selector.