Carbon Ion Irradiation Induced Structural Damage in CdZnTe Crystals and Its Impact on γ-Ray Detector Performance Degradation

Heavy ions irradiation damage is a key factor affecting the long service life and high reliability of nuclear radiation detectors. This work mainly investigates the effects of carbon (C) ion irradiation on crystal structure, optoelectronic, and detection performance of CdZnTe crystals. Geant4 simulation results show that heavy ions mainly deposit at the end of the incident trajectory in CdZnTe crystals. Low-temperature photoluminescence (PL) spectra indicate increased intensity of D₁ (emission peak of A-center) and D₂ (emission peak of dislocation) peaks, suggesting a higher density of Cd vacancies and dislocation-related defects after heavy ion irradiation. Combining transmission electron microscope (TEM) images and Geant4 simulation results, the ion irradiation induced damage is peaked around ∼5 µm below the incident surface of CdZnTe crystals. The formation of intrinsic, extrinsic stacking faults, S-type stacking fault dipoles, and Hirth locks was observed through scanning transmission electron microscopy (STEM) images of CdZnTe crystals after C ion irradiation. The reduction of Te precipitates with a hexagonal structure (∼10 nm) was revealed by high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) results. The heavily damaged zone (0–8 µm) near the surface and the matrix (>8 µm) within the CdZnTe crystal form an n⁺ /n homojunction, leading to barrier height of the Au-CdZnTe interface increased from 0.63 eV before irradiation to 0.87 eV after radiation. The results of γ-ray ²⁴¹Am at 59.5 keV energy spectra show deterioration of energy resolution (from 7.97% FWHM to 16.4% FWHM) after C ion irradiation. These findings provide theoretical guidance for extending the effective service time of detectors and upgrading anti-irradiation technology.