Synaptic transistor based on reversible hydrogenation of graphene channel

Abstract

Graphene transistors with a gate-controlled transition of neuromorphic functions between artificial neurons and synapses have attracted increasing attention because the atomic thickness could be easily modulated by different stimuli, which is very beneficial for synaptic applications. As a modulation method, a graphene electrolyte-gated transistor (EGT) has been proposed, in which the electrical conductance of the graphene channel is modulated by reversible electrochemical hydrogenation of graphene. However, only a sparse physically realized graphene-based synaptic H+-EGTs have been reported due to the difficulty of achieving a high concentration of protons at the electrolyte–graphene interface. Here, we have reported the H+-EGTs with a highly defective graphene channel and a gel electrolyte [H3PO4/poly(vinyl alcohol)], which is based on hydrogenation and dehydrogenation of highly defected-graphene, performing the similar functions as the common artificial synaptic transistors, with good retention (<1% attenuation per minute), analog tunability (>200 nonvolatile states), and precisely controllable resistance (∼0.4% step flipped per synaptic event). In addition, the cyclic voltammetry test was applied to confirm the hydrogenation and dehydrogenation of the graphene channel. It is expected that this principle can provide ideas for designing graphene-based artificial synapses enabling integrated functions of in-memory computing and in-memory sensing for the neuromorphic system.