Synchrotron radiation studies of spectral response features caused by Te inclusions in a large volume coplanar grid CdZnTe detector

TL;DR

This study uses synchrotron radiation to analyze how tellurium inclusions in large CdZnTe detectors affect spectral response, revealing a reduction in charge collection efficiency and depth-dependent spectral features.

Contribution

It provides the first detailed synchrotron-based analysis of Te inclusions' impact on spectral response in large volume CZT detectors, highlighting depth-dependent effects.

Findings

Inclusions cause ~10% shift in peak energy at shallow depths.

Spectral features show two downshifted peaks at greater depths.

The spectral behavior resembles polarization effects in semiconductors.

Abstract

We report preliminary results from a synchrotron radiation study of Te inclusions in a large volume single crystal CdZnTe (CZT) coplanar-grid detector. The experiment was carried out by probing individual inclusions with highly collimated monochromatic X-and gamma-ray beams. It was found that for shallow X-ray interaction depths, the effect of an inclusion on measured energy loss spectra is to introduce a ~10% shift in the peak centroid energy towards lower channel numbers. The total efficiency is however not affected, showing that the net result of inclusions is a reduction in the Charge Collection Efficiency (CCE). For deeper interaction depths, the energy-loss spectra shows the emergence of two distinct peaks, both downshifted in channel number. We note that the observed spectral behavior shows strong similarities with that reported in semiconductors which exhibit polarization effects, suggesting that the underlying mechanism is common.