Heterosynaptic Plasticity in a Vertical Two-Terminal Synaptic Device

Abstract

Vertical two-terminal synaptic devices based on resistiveswitchinghave shown great potential for emulating biological signal processingand implementing artificial intelligence learning circuitries. Tomimic heterosynaptic behaviors in vertical two-terminal synaptic devices,an additional terminal is required for neuromodulator activity. However,adding an extra terminal, such as a gate of the field-effect transistor,may lead to low scalability. In this study, a vertical two-terminalPt/bilayer Sr1.8Ag0.2Nb3O10 (SANO) nanosheet/Nb:SrTiO3 (Nb:STO) device emulates heterosynapticplasticity by controlling the number of trap sites in the SANO nanosheetvia modulation of the tunneling current. Similar to biological neuromodulation,we modulated the synaptic plasticity, pulsed pair facilitation, andcutoff frequency of a simple two-terminal device. Therefore, our synapticdevice can add high-level learning such as associative learning toa neuromorphic system with a simple cross-bar array structure.