High-sensitivity X-ray imaging based on cost-effective and large-size CZT epitaxial crystal

Area of Science:

• Materials Science
• Semiconductor Physics
• Medical Imaging Technology

Background:

• Cadmium Zinc Telluride (CZT) is a leading material for X-ray imaging due to its excellent properties.
• Widespread adoption is hindered by high costs, small wafer sizes, and low sensitivity.
• Existing charge collection methods limit CZT detector performance.

Purpose of the Study:

• To develop a high-quality, large-area CZT epitaxial wafer for advanced X-ray imaging.
• To overcome the limitations of current CZT materials and fabrication techniques.
• To enhance detector sensitivity, reduce noise, and improve spatial resolution.

Main Methods:

• Synthesized a 6-inch CZT epitaxial wafer using close-spaced Epitaxy (CSE).
• Employed a modified two-step growth protocol with an engineered step-flow mode to suppress dislocations.
• Implemented post-growth binary regulation for atomic-level defect engineering to control point defects.

Main Results:

• Achieved an exceptionally narrow double-crystal rocking curve FWHM of 10.44 arcsec, indicating high crystal quality.
• Eliminated deep-level recombination centers while preserving shallow donor states, prolonging carrier lifetime.
• Demonstrated a giant photoconductive gain of 16.52, unprecedented sensitivity (99,701.39 µC Gy_air^-1 cm^-2), a low detection limit (28.5 nGy_air s^-1), and high spatial resolution (4.2 lp mm^-1).

Conclusions:

• The developed CZT material platform offers a scalable solution for next-generation medical digital radiography.
• Atomic-level defect engineering and novel growth techniques significantly enhance detector performance.
• This breakthrough addresses key limitations, paving the way for more effective and accessible X-ray imaging technologies.