Dose-Rate Sensing Using Optimized Rad-Hard Amorphous Silicon Photosensors

Crystalline silicon diodes are replacing gas-filled ionization chambers in dose-rate detectors due to their higher density, scalable manufacturing, and seamless integration into hand-held instruments. However, their performance degrades under high radiation flux due to lattice damage. Hydrogenated amorphous silicon (a-Si:1H) detectors offer batch-processing capability as well as radiation hardness, enabling wide-range dose-rate sensing. We report a high-sensitivity radiation-hard dose-rate sensor based on an undoped a-Si:H photodiode coupled to a NaI(Tl) scintillator. TiO2, previously used as an electron transport layer, was found to degrade performance due to poor stoichiometry and interfacial roughness. Removing TiO2reduced dark current by a factor of 18. This suppression of leakage current enabled low dose-rate detection. Further, optimizing the top ITO layer increased optical absorption in a-Si:H by 30%, boosting quantum efficiency and signal-to-noise ratio. The optimized detector produced a sensitivity of 46.87 μC Gy-1cm-2at 0 V, in response to scintillation light. Gamma-irradiation to 10 kGy (air) caused no degradation in dark current. These results position this platform as a scalable, low-cost, and rad-hard solution for high-performance dosimetry.