Neuromorphic learning and forgetting functions of Pt/Ti_0.99Sc_0.01O_2−δ /Pt multilayer by Schottky barrier modulation

Abstract

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.