Ion Gel-Gated IGZO FETs with Al2O3 Interlayer for Low-Leakage Neuromorphic Devices

Indium-gallium-zinc-oxide (IGZO) field-effect transistors (FETs) using an ion gel gate dielectric layer show great promise for neuromorphic computing owing to their memory functions. Here, we demonstrate ion gel-gated IGZO FETs exhibiting low leakage current level and neuromorphic behaviors by introducing an Al₂O₃ interlayer between the ion gel gate dielectric and source/drain/gate electrodes. It was observed that the Al₂O₃ interlayer effectively reduced the off-state drain current level and counterclockwise hysteresis behavior. Particularly, the IGZO FETs with the Al₂O₃ interlayer exhibited off current level of ~10^-11 A and corresponding on/off ratio of ~10⁷. Meanwhile, IGZO FETs without the Al₂O₃ interlayer showed negligible current switching characteristics owing to high leakage current between source and drain electrodes. Additionally, the ability to tune the synaptic weight through gate bias-dependent modulation enabled the emulation of artificial neural network, as evidenced by a 90.63 % recognition accuracy on the MNIST database. These results suggest that the ion gel-gated IGZO FETs have significant potential in realizing efficient and scalable neuromorphic computing.