Neuromorphic learning and forgetting functions of Pt/Ti0.99Sc0.01O2−δ /Pt multilayer by Schottky barrier modulation

Abstract

We have studied the neuromorphic learning and forgetting functions of Pt/Ti0.99Sc0.01O2–δ /Pt multilayer films with a cross-point array prepared by RF magnetron sputtering and probed their mechanism. The Ti0.99Sc0.01O2–δ layer with an oxygen vacancy ratio of ∼2.5% exhibited high electron–proton mixed conduction. The multilayer draws a nonlinearity 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 times of 14 s and 80 s, respectively. Furthermore, the forgetting LTM function of the human brain is also exhibited by applying negative voltage pulses of 1.0 V with an interval time of 14 s. These neuromorphic current responses are considered to be attributed to the collaborative behaviors of electron, proton, and oxygen vacancy at the Schottky barrier.