Charge Sharing in (CdZn)Te Pixel Detector Characterized by Laser-Induced Transient Currents

Area of Science:

• Materials Science
• Semiconductor Physics
• Detector Technology

Background:

• The performance of cadmium zinc telluride (CdZn)Te pixel detectors is critically dependent on the quality of the bulk material.
• Characterizing charge distribution is essential for understanding detector performance and identifying material defects.

Purpose of the Study:

• To investigate the charge sharing phenomenon in (CdZn)Te pixel detectors.
• To analyze charge distribution as a function of collected charge on adjacent pixels.
• To map charge collection inhomogeneities and their impact on detector performance.

Main Methods:

• Utilized the laser-induced transient current technique (LI-TCT) with 660 nm laser illumination.
• Generated current transients in defined 4 mm² spots on (CdZn)Te pixel detectors.
• Measured charge collection waveforms on the pixel of interest and surrounding pixels at various bias voltages.

Main Results:

• Developed charge collection maps at different bias levels to visualize charge distribution.
• Successfully distinguished regions of charge sharing, material defects, and optimal pixel performance.
• Observed significant material inhomogeneity that complicates the precise assignment of an illuminated spot to a single pixel.

Conclusions:

• Charge sharing is a significant factor affecting (CdZn)Te pixel detector performance.
• Material inhomogeneities directly impact the ability to localize laser-induced signals, influencing defect analysis.
• The LI-TCT method provides valuable insights into spatial charge distribution and material quality in pixelated detectors.