The Investigation Of Starch-based Electrolyte Gated Oxide-based Electric-double-layer Synaptic Transistors

Neuromorphic computing is attracting increasing interests with the remarkable progress in artificial intelligence?AI?.However,the implementation of AI always relies on digital computer based von Neumann configuration.Due to the physical separation of computation module and memory unit in von Neumann configurations,there is the fundamental limitations in AI based on digital computer.Our brain is a highly parallel and energy efficient network,which consists of¹0¹¹ neurons and¹0¹⁵ synapses.Synapse is a basic linkage unit between the presynaptic and postsynaptic neurons.The connection strength is named as synaptic weight which are dynamically enhanced or weaken by adjusting ionic fluxes(for example,Ca²⁺,Na⁺,and K⁺,etc.).The process is considered as the fundament for learning and memory in brain.Thus,brain-inspired neuromorphic devices are expected to provide hardware supports for the developments of AI.Interestingly,ion-conducting electrolytes possess unique ion-modulation and ion relaxation behavior.Thus,ion-conducting electrolyte gated transistors have great potentials in neuromorphic engineering.The main research contents and research results are included as followed:Firstly,starch-based biopolymer electrolyte film was fabricated by drop-coating method.Owing to the protonic transporting in starch-based biopolymer electrolyte film,the protons will migrate to the channel layer and form a proton/electronic coupling.The measured proton conductivity and EDL capacitance are 5.2×10^-3 S/cm and 3.5?F/cm²in starch-based biopolymer electrolyte film,respectively.Secondly,due to the good compatibility between starch-based biopolymer electrolytes and oxide semiconductor,and the electric-double-layer coupling at the gate dielectric/channel layer interface,the fabricated starch-based biopolymer electrolyte gated oxide-based EDL transistors in this paper have excellent electrical properties at a low operating voltage.The current ON/OFF ratio,threshold voltage,field-effect mobility and subthreshold swing of the proposed transistors are estimated to be 1×107,0.2 V,14.9 cm²/Vs and 99.7 mV/decade,respectively.It is found that the oxide-based EDL transistor arrays prepared in this paper are transparent to visible light.An average transmittance in the visible range?380-800 nm?is 68%.Finally,the proposed oxide EDL transistors can operate stably at a low operating voltage of 1.5 V in the stability test.During the bias measures of the transistor,it was found that when a positive bias was applied to the gate electrode,the transfer curve of the transistor drifted to the left,and the negative was reversed.The phenomenon is suitable for the bionics of synaptic plasticity behaviors.This paper expands the application of starch-based biopolymer electrolyte gated transistors in the bio-synaptic biomimetic field.Some synaptic behaviors such as excitatory post-synaptic currents,pulse-paired facilitation,etc.had been successfully demonstrated in this transistor.In addition,post-tetanic potentiation behaviors and the activity-dependent post-tetanic potentiation behaviors were demonstrated in detail.In summary,the proposed starch-based biopolymer electrolyte gated synaptic transistor may have potential applications in the development of artificial neural networks in the future.