Self-rectifying and forming-free nonvolatile memory behavior in single-crystal TiO2 nanowire memory device

Abstract Vertically aligned single-crystal TiO2 nanowire with preferred orientation along the [001] direction has been directly synthesized using a simple low-temperature hydrothermal process. A stable self-rectifying and forming-free nonvolatile memory behavior with a high resistance ratio of more than two orders of magnitude has been achieved in the TiO2 nanowire memory device, which can be remained for over 103 s and without any obvious decline. Furthermore, the memory behavior in the low resistance state is attributed to the Ohmic conduction mechanism, while the high resistance state is governed by the trap-regulated SCLC mechanism. In addition, the metallic conductive filament model adjusted by oxygen vacancies has been proposed, in which the self-rectifying and forming-free nonvolatile memory behavior could be ascribed to the formation and erasure of the Magneli phase conductive filament in the TiO2 nanowire memory device. This work suggests the wide prospects of the TiO2 nanowire memory device for next-generation nonvolatile memory applications.