Artificial Synaptic InGaZnO Thin-Film Transistor With Long Retention Behavior Using Al2O3/SiO2 Gate Insulator

We present a coplanar amorphous InGaZnO (a-IGZO) synaptic thin film transistor (TFT) with counterclockwise hysteresis using an aluminum oxide (Al2O3)/SiO2 gate insulator (GI). The excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), short-term plasticity (STP), and long-term plasticity, which are biological synaptic characteristics, are demonstrated by positive charge trapping in the Al2O3 layer. Long retention time can be possible by surface charge in the SiO2, a charge-blocking layer. As a result, multi-level channel conductance can be modulated with positive and negative gate pulses. These results prove synaptic a-InGaZnO TFT with Al2O3/SiO2 stack GI for high-density neuromorphic devices.