Analog Synaptic Devices Based on IGZO Thin-Film Transistors with a Metal–Ferroelectric–Metal–Insulator–Semiconductor Structure for High-Performance Neuromorphic Systems

A ferroelectric thin-film transistor (FeTFT)-based synaptic device with an indium–gallium–zinc oxide (IGZO) channel and a metal–ferroelectric–metal–insulator–semiconductor (MFMIS) structure is reported. The fabricated FeTFT exhibits a highly linear conductance response (|α| = 0.21) with a large dynamic range (G_max/G_min ≈ 53.2), although identical program pulses are applied to the device. In addition, because the inner metal layer of the FeTFTs has an MFMIS structure, the electric field is uniformly applied to the entire IGZO channel, which reduces the cycle-to-cycle variation (σ = 0.47%) in the conductance responses. In the system simulation with the measured synaptic characteristics, the high classification accuracy of ≈97.0% is achieved in the MNIST image set, verifying the feasibility of FeTFT-based neuromorphic systems.