Sputtered Electrolyte-Gated Transistor with Modulated Metaplasticity Behaviors

Electrolyte-gated transistors have been proposed as promising candidates for neuromorphic applications. Synaptic plasticity behaviors and most recently synaptic metaplasticity or plasticity of plasticity behaviors have been mimicked on electrolyte-gated transistors. In this work, indium-gallium-zinc-oxide thin-film transistors gated with sputtered SiO2 electrolytes are fabricated. Both spiking-width-dependent and spiking-height-dependent metaplasticity behaviors are successfully mimicked. The effects are modulated by the drain voltage bias. A physical model based on the electric-double-layer coupling, the RC circuit theory, and the stretched-exponential diffusion is proposed for the metaplasticity behaviors. The experiment data have been well fitted by the proposed model. Meanwhile, the Bienenstock, Cooper, and Munro learning rule, which describes the threshold-tunable, spiking-rate-dependent plasticity behaviors, is also successfully emulated, providing insight into the synaptic metaplasticity behaviors in electrolyte-gated synaptic transistors.