High-performance CZT X-ray imaging device with ultrahigh sensitivity and ultralow detection limit

High-quality cadmium zinc telluride (CZT) single crystals are essential for achieving optimal radiation detection performance and serve as the foundation for advanced X-ray detectors. Large-size epitaxial films can be effectively synthesized using close-space sublimation (CSS), enhancing the potential of optoelectronic flat-panel detectors for high-resolution imaging applications. However, current applications of CZT in medical imaging face several limitations, including low sensitivity, instability at high frame rates, and prolonged response times. To address these challenges, a two-step approach was employed: first, annealing the CZT epitaxial film in Te₂ atmosphere, followed by substrate removal. This process resulted in a significant increase in the detector's resistivity to 1.6842 × 10¹⁰Ω·cm and its sensitivity to 5708 μC Gy⁻¹cm⁻². Furthermore, the introduction of sub-bandgap light illumination reduced the rise time to 0.1667 s and the fall time to 0.2555 s. The rise time was shortened to 37.23 % of the original, and the fall time was shortened to 91.28 % of the original. Collectively, these modifications lowered the detector's detection limit to 0.0347 μGy/s, while further improving stability of photocurrent. To demonstrate its imaging capabilities, the detector was integrated into the TFT array. X-ray images of a ballpoint pen were subsequently acquired, in which the casing, ink cartridge, and spring are clearly resolved, indicating the system's high-contrast and high-resolution performance. These results indicate that large-size CZT epitaxial single crystals, processed using this optimized method, are promising candidates for next-generation high-performance X-ray flat-panel detectors.