Characterization of the Uniformity of High-Flux CdZnTe Material.

Matthew Charles Veale,Matthew David Wilson,Lydia Jowitt,Rhian Mair Wheater,Georgios Prekas,Paul Seller,Andreas Schneider,Pramodha Marthandam,John Lipp,Krzysztof Iniewski,Matthew David Hart,Paul Booker,Simon Cross,Conny Christoffer Tobias Hansson

doi:10.3390/s20102747

Abstract

Since the late 2000s, the availability of high-quality cadmium zinc telluride (CdZnTe) has greatly increased. The excellent spectroscopic performance of this material has enabled the development of detectors with volumes exceeding 1 cm3 for use in the detection of nuclear materials. CdZnTe is also of great interest to the photon science community for applications in X-ray imaging cameras at synchrotron light sources and free electron lasers. Historically, spatial variations in the crystal properties and temporal instabilities under high-intensity irradiation has limited the use of CdZnTe detectors in these applications. Recently, Redlen Technologies have developed high-flux-capable CdZnTe material (HF-CdZnTe), which promises improved spatial and temporal stability. In this paper, the results of the characterization of 10 HF-CdZnTe detectors with dimensions of 20.35 mm × 20.45 mm × 2.00 mm are presented. Each sensor has 80 × 80 pixels on a 250-μm pitch and were flip-chip-bonded to the STFC HEXITEC ASIC. These devices show excellent spectroscopic performance at room temperature, with an average Full Width at Half Maximum (FWHM) of 0.83 keV measured at 59.54 keV. The effect of tellurium inclusions in these devices was found to be negligible; however, some detectors did show significant concentrations of scratches and dislocation walls. An investigation of the detector stability over 12 h of continuous operation showed negligible changes in performance.

Highlights

Cadmium zinc telluride (CdZnTe) is a compound semiconductor that has been studied for many years for its application in the detection of radiation, X-rays and γ-rays
The results are reported for the characterization of a sample of 10 pixelated HF-cadmium zinc telluride (CdZnTe) detectors, each with an area of 4.2 cm2, which were fabricated by Redlen Technologies and are read out with the Science and Technology Facitlities Councils’s (STFC) HEXITEC Application Specific Integrated Circuit (ASIC) [10]
The average Full Width at Half Maximum (FWHM) measured in the detector over 9 h was found to change from 770 to 840 eV at 28 °C and 760 to 780 eV at 18 °C

Summary

Introduction

Cadmium zinc telluride (CdZnTe) is a compound semiconductor that has been studied for many years for its application in the detection of radiation, X-rays and γ-rays The advantage of this material over traditional direct conversion detector materials like silicon and germanium is its high density (~5.8 g cm−3 ) and high resistivity (~1011 Ω cm), which make it ideally suited for the detection of high energy X-rays and γ-rays without the need for cryogenic cooling. Sensors 2020, 20, 2747 been prone to the polarization phenomenon in which the electrical field in the detector is modified over time due to a buildup of trapped charge in the crystal [2] This has limited the use of CdZnTe detectors to application areas, such as nuclear material detection, where photon fluxes are much lower [3]. In order for CdZnTe detectors to be of use in high photon flux applications like

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Conclusion