Study on displacement damage of 4H-SiC neutron detector based on Geant4

BackgroundRadiation detectors based on silicon carbide (SiC), a third-generation wide-bandgap semiconductor material, exhibit exceptional radiation resistance and high-temperature resistance, along with ultrafast temporal response. These properties make SiC an ideal semiconductor detector material for pulsed radiation and intense radiation fields, particularly suitable for strong radiation field measurements in extreme environments.PurposeThis study aims to investigate the critical problem of how neutron irradiation degrades the electrical performance of 4H-SiC materials, thereby limiting the reliable operation of 4H-SiC based radiation detectors in high intense neutron radiation fields.MethodsThe Monte Carlo simulation software Geant4 was employed to simulate the transport processes of various neutrons in a 4H-SiC neutron detector, and investigate the displacement damage and defect distribution characteristics within the sensitive layer of SiC. Variations of non-ionizing energy loss (NIEL) and primary knock-on atom (PKA) energy spectra with incident neutron energywere analyzed to explore distinct irradiation damage patterns in the sensitive layer of the 4H-SiC device induced by different neutron energies.ResultsSimulation results indicate that within the sensitive layer of the detector at micrometer-scale thickness, the NIEL is uniformly distributed along the incident depth direction. Higher neutron energies lead to greater PKA kinetic energies and a wider variety of PKA species whilst most PKAs remain in the low-energy range. In terms of PKA types, Si/C PKAs account for a relatively large proportion. Under high-energy neutron irradiation, inelastic scattering is the major contributor to displacement damage within the material. Additionally, other secondary ions generated through processes such as charged particle emission increase rapidly, further leading to irradiation damage in the sensitive layer of the detector.ConclusionsThe results of this study hold positive scientific significance for promoting the application of wide-bandgap semiconductor radiation detection technology in extreme environments.