Damage generation mechanism and performance degradation of CdZnTe radiation detectors in neutron radiation field

Semiconductor radiation detectors used in nuclear power plants and other environments are inevitably exposed to neutron, γ-ray and other high-energy radiation, which can damage the crystal structure of semiconductors and thus degrade the detector performance. Here, we investigate the effects of neutron irradiation on the microstructure, photoelectric and radiation detection performance of CdZnTe detectors. Low-temperature photoluminescence (PL) spectra show that the dislocation related defect concentration in the irradiated crystals increases with increasing fluence. The infrared (IR) transmittance of the irradiated crystal decreases compared with that of the unirradiated crystal, which also indicates an increase in the dislocation density. The presence of stacking faults, stacking fault dipoles and dislocation locks in the irradiated CdZnTe crystals has been revealed by transmission electron microscopy (TEM). The energy resolution of γ-ray from ²⁴¹Am@100 V is degraded from 5.86 % before irradiation to 10.72 % after irradiation at 5.6 × 10¹⁰ n/cm². In addition, the mobility-lifetime product of electron (μτ)_e in CdZnTe detectors is reduced from 4.8 × 10^-3 cm²/V before irradiation to 7.02 × 10^-4 cm²/V after irradiation at 5.6 × 10¹⁰ n/cm². I-V test show that the barrier height of the CdZnTe detector decreases with the increase of neutron irradiation fluence, leading to a decrease in resistivity. Time-of-flight (TOF) tests demonstrate that the electron mobility after irradiation decreases with increasing irradiation fluence. Notably, the maximum neutron fluence used in this study is 3.9 × 10¹¹ n/cm², at which the CdZnTe radiation detector is not completely damaged. This study mainly investigates the radiation damage mechanism, induced defect characteristics and performance degradation of CdZnTe crystals by neutron irradiation, aiming to provide theoretical guidance for improving the radiation-resistant properties of detectors.