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6CCVD Research

Characterisation and quantification of the `Excess-Leakage-Current' effect in Redlen HF-CdZnTe at > 106 ph s-1 mm-2

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2025-10-01
JournalJournal of Instrumentation
AuthorsB. D. Cline, David Banks, Matthew Bishop, Adam Davis, J. R. Harris
InstitutionsRutherford Appleton Laboratory, Diamond Light Source

Abstract

Section titled “Abstract”

Abstract In this paper, results are presented from the characterisation of a 2 mm thick Redlen Technologies high-flux-capable Cadmium Zinc Telluride (HF-CZT) sensor hybridised to the small-pixel, spectroscopic-imaging HEXITEC_MHz ASIC. Dynamic datasets were taken on the B16 Test Beamline at the Diamond Light Source to study a previously-identified ‘excess-leakage-current’ phenomenon in HF-CZT, where additional leakage current was temporarily generated upon the application of an X-ray flux. A study of the response of the detector as a function of X-ray intensity demonstrated a measurable excess leakage current signal above 10 5 ph s -1 mm -2 . At a 20 keV flux of 7.81 × 10 6 ph s -1 mm -2 , this effect contributed a signal equivalent to 3.79 ± 1.59 nA mm -2 in addition to the expected photocurrent. On removal of X-rays at this flux, this excess leakage current took ∌ 10 s to decay below the noise floor of the detector. This long lifetime has implications for detectors required to operate at high frame rates and fluxes. The use of a small-pixel detector also allowed the spatial variation of this effect to be studied. A per-pixel comparison between the magnitude of the excess leakage current and the spectroscopic performance of the pixel showed no correlation. This suggests that the phenomenon is less likely to be a bulk-crystal effect and more likely the result of the properties of the CZT surface or metal/semiconductor interface. An Arrhenius analysis of the temperature-dependence of the dark and excess leakage currents in the detector yielded values of 0.69 ± 0.04 eV and 0.13 ± 0.01 eV respectively. The change in dark current with temperature is consistent with deep levels pinning the Fermi level close to the mid band gap, whilst the activation energy of the excess leakage current suggests shallower defects at the metal-semiconductor interface are responsible.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
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  2. 2022 - Characterization of High-Flux CdZnTe with optimized electrodes for 4th generation synchrotrons [Crossref]
  3. 2024 - Characterisation of Redlen HF-CdZnTe at gt; 106 ph s-1 mm-2 using HEXITECMHz [Crossref]
  4. 2022 - Polarization effect of Schottky-barrier CdTe semiconductor detectors after electron irradiation [Crossref]
  5. 2012 - Characterization of M-pi-n CdTe pixel detectors coupled to HEXITEC readout chip [Crossref]
  6. 2018 - Odin - a Control and Data Acquisition Framework for Excalibur 1M and 3M Detectors
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  8. 2014 - CZT detector technology for medical imaging [Crossref]
  9. 2017 - Characterisation of Redlen high-flux CdZnTe [Crossref]
  10. 2020 - Characterization of the Uniformity of High-Flux CdZnTe Material [Crossref]

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