Two-Terminal Structured Synaptic Device Using Ionic Electrochemical Reaction Mechanism for Neuromorphic System

An ionic electrochemical-reaction-based two-terminal synaptic device (Ionic Synapse) is developed for improved weight updating in hardware-based neuromorphic systems. The developed ionic synapse consists of an anode and a cathode that have the typical structure of a rechargeable battery. It can migrate metal ions from the anode (cathode) to the cathode (anode) under electrical bias, yielding total conductance changes. Analysis of the fabricated device reveals that the conductance changes are strongly dependent on the amounts of migrated ions, which can be sensitively controlled using applied identical pulses. Consequently, improved linearity for weight-updating is successfully achieved. These findings indicate the potential of the ionic electrochemical reaction mechanism for the realization of a desirable two-terminal synaptic device.