Enhancing the photoelectric synaptic plasticity of β-Ga2O3 films via improving crystalline quality

Solar-blind ultraviolet (SBUV) photoelectric bionic synapses, which has the advantages of anti-interference, highspeed transmission, computing-in-memory, is considered to help solve the severe challenges faced by the Von Neumann architecture computers. Diverging from conventional photodetectors (PDs), photoelectric bionic synapses necessitate robust synaptic plasticity-a trait that entails sustaining an excited state for extended periods post-optical stimulation. Traditionally, the photoelectric synaptic plasticity observed in gallium oxide (Ga2O3) has been attributed to the presence of defects, with high crystalline quality often deemed detrimental to such functionalities. However, in this paper, by enhancing the crystalline quality of beta-Ga2O3 films, we significantly boost the synaptic plasticity of the device, extending the recovery time of the devices from 0.22 s to over 40 s. Furthermore, the synaptic device boasts multifaceted functionalities, including multi-level storage, shortterm memory (STM), and long-term memory (LTM). Besides, the device demonstrates excellent voltage stability (under 1-10 V) and high-temperature operability (at 630 K). Combined with the analysis of film characteristics, we posit that the synaptic plasticity exhibited by these high-quality beta-Ga2O3 films stems from its intrinsic indirect bandgap.