Investigation of the Performance Degradation of 4H-SiC Neutron Detectors Using MCNP and TCAD

4H-SiC belongs to the family of the third-generation semiconductors and features excellent properties, e.g., high radiation resistance, high charge collection efficiency (CCE), exceptional thermal stability, and low sensitivity to $\gamma $ -rays. These advantages make 4H-SiC suitable for developing neutron detectors used in intense neutron fields characteristic of tokamaks. However, 4H-SiC detectors suffer from performance degradation after neutron irradiation to high fluence. The knowledge of the degradation evolution of 4H-SiC detector performance parameters with neutron fluence in specific situations can not only help optimize the detector design but also help understand and even correct experimental data for its better use. The technology computer-aided design (TCAD) software is used here to predict the detailed parameters in 4H-SiC bulk underlying the detector performance degradation resulting from neutron irradiations in the vicinity of experimental advanced superconducting tokamak (EAST) tokamak, a fusion device, and the reason for the detector performance degradation caused by neutron irradiation is analyzed. Our 4H-SiC detector damage analysis model employed in TCAD yields CCE values, which have a reasonable consistency with experimental results obtained in references for neutron fluences up to $5\times 10^{{15}}$ cm $^{-{2}}$. Additionally, at the neutron fluence of $10^{{15}}$ cm $^{-{2}}$ , the electric fields within 4H-SiC bulk have significant distortions. Nonetheless, the CCE remains at about 40%, demonstrating an extremely high tolerance to neutron irradiations. Meanwhile, our study reveals that enhancing carrier transport rates and strengthening the field within the sensitive region can effectively mitigate the degradation of detector performance, thereby enhancing the detector's radiation tolerance.