Zn-doped Ga2O3 based two-terminal artificial synapses for neuromorphic computing applications
Amorphous gallium oxide (a-Ga2O3) suffers from low carrier concentration and limited mobility, impeding its use in neuromorphic computing. This study fabricates Zn-doped Ga2O3 (ZGO) two-terminal artificial synaptic devices via radio-frequency magnetron sputtering (RFMS) under oxygen-free conditions. Compared to undoped Ga2O3, the ZGO device exhibits a 106-fold increase in excitatory post-synaptic current under 254 nm illumination, with response intensity positively correlated to optical pulse parameters. Under light pulse modulation, the devices demonstrate dynamic transitions from short-term plasticity to long-term plasticity, including paired-pulse facilitation and a learning-forgetting-relearning process. Electrical and optical energy consumptions of synaptic events are as low as 28 fJ and 2 nJ, respectively. Mechanism analysis attributes the persistent photoconductivity effect in ZGO thin films to abundant oxygen vacancies. A multi-layer perceptron simulation based on ZGO devices achieves 90.74% accuracy in handwritten digit recognition and maintains 76.18% accuracy under 50% noise. Zn doping provides a new material design approach for Ga2O3-based neuromorphic devices, demonstrating potential for future neuromorphic computing applications.