Improvement of weight stability in Li-ion-based electrolyte-gated transistor synapse by silica protective process

Abstract

Li-ion-based electrolyte-gated transistors (Li-EGTs) have been extensively studied as synaptic devices due to their potential to provide good analog switching of channel conductance, which is a desirable property for the emulation of synaptic weight modulation. However, the chemical activity of lithium ion electrolytes during device fabrication is detrimental to the analog switching stability of the Li-EGT and limits its potential application. In this work, we developed a silica protective process for Li-EGT fabrication. By continuously depositing the lithium ion electrolyte and silica protective layer, we achieved the isolation of the electrolyte from the external environment during device fabrication. The electrical characterization shows that the analog switching stability of the fabricated Li-EGT is significantly improved. Based on the experimental data, a recognition accuracy of ∼96% has been demonstrated in the Li-EGT array by simulations using the handwritten digit data sets. The present results give insight into the large-scale fabrication of the Li-EGT synapse for neuromorphic computing.