Self-Rectifying and Artificial Synaptic Characteristics of Amorphous Ta₂O₅ Thin Film Bilayer Memristor

Amorphous Ta₂O₅ (ATa₂O₅) film has different electrical properties depending on the growth conditions. ATa₂O₅ film, which was grown under the Ar/O₂ atmosphere with a high O₂ pressure, has insulating property and thus it can be used as a tunneling barrier. ATa₂O₅ film, which was grown under O₂ deficient condition, shows resistance random access memory (ReRAM) characteristic, indicating that it can be used for switching layer. ATa₂O₅ film for tunneling barrier was grown on TiN/SiO₂/Si (TSS) at room temperature and annealed under oxygen condition by RTA. ATa₂O₅ film for bipolar switching was grown on tunneling barrier. Self-rectifying characteristics were observed in an ATa₂O₅ bilayer memristor. The current conduction of this ATa₂O₅ bilayer memristor in the high-resistance state (HRS) is explained by Schottky emission, direct tunneling, and Fowler–Nordheim (FN) tunneling. In the low-resistance state (LRS), this ATa₂O₅ memristor shows insulating behavior, indicating that oxygen vacancy filaments were not formed. The current conduction of this memristor in the LRS was attributed to direct tunneling and FN tunneling. Moreover, ATa₂O₅ bilayer exhibited artificial synaptic properties. Therefore, the ATa₂O₅ bilayer memristor can be used as an artificial synapse for neuromorphic computing.