Observing resistive switching behaviors in single Ta2O5 nanotube-based memristive devices

Recently, one-dimensional (1D) metal oxide nanostructured materials have attracted considerable attention owing to their appealing properties and functionalities. In previous studies, 1D metal oxide materials have been widely applied to electronic components; among them, resistive switching memristive devices are one of the most promising applications. The resistive switching mechanism in thin-film dielectric layers is widely explored, but understanding of that in 1D materials is insufficient. Moreover, a direct evidence regarding the switching behavior resulting from the formation and dissolution of conductive filaments is still lacking. In this study, a single Ta2O5 nanotube (NT) was fabricated as an Ag/Ta2O5 NT/Ag device, and its electrical properties were examined, which demonstrated a stable resistance state with a large memory window of approximately 107. The in-situ transmission electron microscopy (TEM), high-resolution TEM, energy dispersive spectroscopy techniques and electron energy loss spectroscopy (EELS) were used to establish a unique resistive switching mechanism in such devices for the first time. In addition, the crystallinity of the Ta2O5 NTs was well-controlled through rapid thermal annealing and furnace. The relationship between crystallinity and electrical properties was investigated. Oxygen vacancies play a crucial role in resistance switching, and thus, their amounts were determined using EELS. Therefore, the established mechanism revealed the dynamic behavior of Ta2O5 NTs in memristive devices, which allows the exploration of a wide range of NT materials for memory applications.