Synergistic defect-interface-photocarrier modulation based on IGZO/HfO₂ heterojunction memristors for neuromorphic...

Neuromorphic visual systems require optoelectronic synaptic devices capable of integrating optical sensing, memory, and processing. However, HfO₂-based memristors still face challenges in simultaneously achieving stable resistive switching, efficient light-modulated synaptic plasticity, and device-level visual processing. Here, a sol-gel-derived Au/IGZO/HfO₂/FTO heterojunction memristor is developed for optoelectronic synaptic emulation and neuromorphic visual applications. The IGZO/HfO₂ heterointerface enables synergistic regulation of oxygen-vacancy-related defects, interfacial charge trapping/detrapping, and photogenerated carrier transport, leading to stable bipolar resistive switching and tunable optoelectronic synaptic behavior. The device emulates diverse synaptic functions, including short-term plasticity, long-term potentiation/depression, paired-pulse response, and learning-forgetting-relearning processes. Its excitatory postsynaptic current can be modulated by optical pulse width, power density, pulse number, and read voltage, with a minimum synaptic energy consumption of 11.925 nJ at 0.001 V under an optical pulse width of 0.5 s. Furthermore, a device-array-based feedback-circuit system enables adaptive image contrast enhancement, while neural network simulations achieve recognition accuracies of 97.94% for MNIST and 84.18% for Fashion-MNIST. These results demonstrate the potential of IGZO/HfO₂ heterojunction memristors for low-power neuromorphic visual preprocessing and recognition.