Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Area of Science:

• Materials Science
• Semiconductor Physics
• Radiation Detection

Background:

• Cadmium Zinc Telluride (CdZnTe) detectors exhibit polarization effects under high photon flux, hindering performance.
• Poor hole transport in traditional CdZnTe materials is the primary cause of polarization.
• This limitation necessitates the development of advanced materials for high-flux applications.

Purpose of the Study:

• To evaluate the performance of a novel high-flux capable CdZnTe (HF-CdZnTe) material in mitigating polarization effects.
• To quantify charge sharing and charge loss in a pixelated HF-CdZnTe detector.
• To assess the impact of improved hole transport on detector performance and spectral resolution.

Main Methods:

• Fabrication and testing of a 2 mm thick pixelated HF-CdZnTe detector with 250 μm pixel pitch.
• Measurement of charge sharing and charge loss for bipixel events.
• Comparison with a standard Cadmium Telluride (CdTe) detector and Monte Carlo simulations.
• Analysis of spectral resolution and electric field uniformity.

Main Results:

• HF-CdZnTe detectors demonstrated significantly reduced polarization effects compared to conventional materials.
• Minimal charge loss was observed in bipixel charge sharing events, achieving a spectral resolution of 1.63 ± 0.08 keV FWHM at 59.5 keV.
• Depth of interaction was identified as a factor influencing charge loss in shared events.
• Simulations supported experimental findings, indicating a uniform electric field.

Conclusions:

• The developed HF-CdZnTe material effectively mitigates polarization phenomena, enabling high-flux operation.
• Improved hole transport in HF-CdZnTe enhances charge collection efficiency, particularly in thick, pixelated detectors.
• The results highlight the potential of HF-CdZnTe for next-generation radiation detection systems requiring high count rates and excellent spectral resolution.