We investigated the nanoionics-based neuromorphic function of Pt/Ti0.96Co0.04O2-δ/Pt multilayer with cross-point structure prepared by RF magnetron sputtering. This multilayer exhibits the electro-ion mixed conduction and the nonlinear current-voltage characteristic based on the Schottky barrier between Pt and Ti0.96Co0.04O2-δ layers. When the low electrical pulse of 0.8 V was applied with short interval time of 14 s, the current modulation corresponding to the long-term memorization (LTM) was observed, though the current response at the long interval time of 80 s was the short-term memorization (STM). The O 1s photoemission spectrum showed the OH- peak that contributes to the electron-ion mixed conduction. The current responses with both LTM and STM are considered to be due to the local proton migration at near the Schottky barrier.

We have investigated the neuromorphic learning and forgetting functions of Pt/Ti0.99Sc0.01O2–δ/Pt multilayer with a cross-point array prepared by RF magnetron sputtering and probed their mechanism. The Ti0.99Sc0.01O2–δ layer with oxygen vacancy ratio of ~2.5% exhibited high electron-proton mixed conduction. The multilayer draws a nonlinear current-voltage curve owing to the Schottky barrier between the upper or lower Pt and Ti0.99Sc0.01O2–δ layers. Two singular current modulations corresponding to the learning long-term memory (LTM) and the short-term memory (STM) functions were observed by applying positive voltage pulses of 0.8 V with interval time of 14 s and 80 s, respectively. Furthermore, the forgetting LTM function of the human brain also exhibited by applying negative voltage pulses of 1.0 V with interval time of 14 s. These neuromorphic current responses are considered to attribute to the collaborative behaviors of electron, proton, and oxygen vacancy at the Schottky barrier.