Monte Carlo Analysis of Silicon Carbide Neutron Detector With Double Conversion Layer

In this paper, the performance of SiC-based neutron detector was investigated using GEANT4 toolkit. Thin-film-coated and trench type neutron detectors were considered and their intrinsic detection efficiency were calculated according to the relevant structural parameters, with Low-Level Discriminator (LLD) value fixed at 300 keV. For thin-film-coated detector, the analysis carried out for varied layer thicknesses of
¹⁰
B and
⁶
LiF showed that the intrinsic detection efficiency increases with the increase of thickness, and reaches the maximum value at the critical thickness and thereafter found to gradually decrease. Due to the self-absorption effect of the conversion material, the intrinsic detection efficiency of the thin-film-coated SiC neutron detector is limited to less than 5%. Fortunately, the trench type SiC neutron detector can break through this limitation. However, under current process conditions, SiC can only be used for shallow trench etching. In order to increase the neutron detection efficiency as high as possible in the limited trench depth, we have proposed a scheme of filling the trench with a double conversion layer, which can significantly improve the intrinsic detection efficiency of neutrons compared with the traditional trench structure with a single conversion layer. Apart from estimating the intrinsic detection efficiency, the energy deposition spectrum in the SiC detector region by the produced secondary charged particles upon thermal neutron interaction with conversion material(
¹⁰
B and
⁶
LiF) have also been researched for various structural parameters such as conversion layer thickness, trench width and trench gap of detector.