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 Al2O3/TiO2 double-oxide structure are first demonstrated. The field-induced oxygen vacancy migration model in the TiO2 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.