Dual-Terminal Stimulated Heterosynaptic Plasticity of IGZO Memtransistor with Al₂O₃/TiO₂ Double-Oxide Structure

Recently, memtransistors have attracted considerable attention as promising building blocks for highly efficient neuromorphic synaptic devices, facilitating heterosynaptic plasticity and a large number of multilevel states. However, the resistive switching characteristics of memtransistors have been limited to a two-dimensional transition-metal dichalcogenide. Here, reliable gate-tunable resistive switching characteristics of an InGaZnO (IGZO) memtransistor with an Al 2 O 3 /TiO 2 double-oxide structure are first demonstrated. The field-induced oxygen vacancy migration model in the TiO 2 layer is proposed to describe the dynamic Schottky barrier modulation between the Al electrode and IGZO channel, causing the resistive switching property. Reliable heterosynaptic plasticity and a highly precise multilevel state can be achieved using dual-terminal presynaptic stimuli. The IGZO memtransistor also showed remarkable endurance in long-term potentiation and depression cycling under 5000 drain and gate pulses. The high pattern recognition accuracies of 90.4 and 86.5% obtained from the drain- and gate-stimulated conductance changes were validated using an artificial neural network (ANN) simulation. Thus, our double-oxide structure designed to realize memtransistor characteristics paves the way for high-performance synaptic circuitry with precisely controlled heterosynaptic plasticity, leading to an advanced neuromorphic system.