Effects of Gamma Irradiation on the Artificial Spiking Neurons Based on NbO_x Threshold Switching Memristor

Artificial spiking neurons (ASNs) have attracted significant attention for neuromorphic computing systems intended for deep-space and radiation-rich environments. However, their reliability under ionizing radiation remains largely unexplored. In this work, the effects of gamma-ray irradiation on ASNs based on NbO_x threshold switching (TS) memristors are systematically investigated under both offline (no applied voltage) and online conditions (applied voltage). Under offline irradiation up to 1 Mrad (Si), all devices retain robust threshold switching characteristics and stable oscillation behavior, demonstrating strong intrinsic tolerance to gamma exposure. During online irradiation, the ASN maintains stable oscillation under continuous irradiation up to a total dose of 1 Mrad for 65 min, confirming reliable operation. After irradiation, the threshold current (I_th) decreases significantly from ≈100 µA to <50 µA, while the threshold voltage (V_th) remains generally stable. Consequently, the spike energy consumption decreases from 65 nJ per spike to 16 nJ after 1 Mrad exposure. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) reveal increased oxygen vacancy concentration in the NbO_x thin film after irradiation, while the surface morphology remains largely unchanged. These results highlight the radiation tolerance and low-power potential of NbO_x TS memristors for neuromorphic computing in radiation environments.