Artificial Synapse\nEmulated through Fully Aqueous Solution-Processed Low-Voltage In₂O₃ Thin-Film Transistor with Gd₂O₃ Solid Electrolyte

Abstract

Brain-like neuromorphic computing system provides an\nalternative approach for the future computer for its characteristics\nof high-efficiency, power-efficient, self-learning, and parallel computing.\nTherefore, the imitation of synapse behavior based on microelectronics\nis particularly important. Recently, the synaptic transistors have\nreceived widespread attention. Among them, solid oxide-based synaptic\ntransistors are more compatible with the large-scale fabrication than\nthe liquid and organic-based transistors. So the development of oxide\nsynaptic transistor is required. Here, a novel aqueous solution-processed\nGd₂O₃ is suggested to be the solid electrolyte\nfor synaptic transistors. The microstructure and the dielectric properties\nof Gd₂O₃ film are investigated, which show the\npotential for the simulation of synaptic transmission. Then, the fully\naqueous solution-processed In₂O₃/Gd₂O₃ thin-film transistor (TFT) is fabricated. The device\nexhibits an acceptable electrical performance with a small threshold\nvoltage of 1.24 V, and a small subthreshold swing of 0.12 V/decade.\nThe artificial synapse behavior is stimulated and the short-term plasticity\nof In₂O₃/Gd₂O₃ TFT is\nstudied. The dependence of its excitatory postsynaptic current on\npresynaptic pulse magnitude, width, and frequency is verified. Besides,\nthe synapse behavior of devices under continuous illumination stresses\nis investigated. The lights with different photon energy have different\neffects on the synaptic transmission, which is related to the ionization\nof oxygen vacancies. Our results demonstrate that fully aqueous solution-processed\nIn₂O₃ TFT with Gd₂O₃ solid\nelectrolyte is a candidate for the synaptic transistor.