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Proceedings Paper

Characterization of high-resistivity CdTe and Cd0.9Zn0.1Te crystals grown by Bridgman method for radiation detector applications
Author(s): Krishna C. Mandal; Ramesh M. Krishna; Rahmi O. Pak; Mohammad A. Mannan
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Paper Abstract

CdTe and Cd0.9Zn0.1Te (CZT) crystals have been studied extensively for various applications including x- and γ-ray imaging and high energy radiation detectors. The crystals were grown from zone refined ultra-pure precursor materials using a vertical Bridgman furnace. The growth process has been monitored, controlled, and optimized by a computer simulation and modeling program developed in our laboratory. The grown crystals were thoroughly characterized after cutting wafers from the ingots and processed by chemo-mechanical polishing (CMP). The infrared (IR) transmission images of the post-treated CdTe and CZT crystals showed average Te inclusion size of ~10 μm for CdTe and ~8 μm for CZT crystal. The etch pit density was ≤ 5×104 cm-2 for CdTe and ≤ 3×104 cm-2 for CZT. Various planar and Frisch collar detectors were fabricated and evaluated. From the current-voltage measurements, the electrical resistivity was estimated to be ~ 1.5×1010 Ω-cm for CdTe and 2-5×1011 Ω-cm for CZT. The Hecht analysis of electron and hole mobility-lifetime products (μτe and μτh) showed μτe = 2×10-3 cm2/V (μτh = 8×10-5 cm2/V) and 3-6×10-3 cm2/V (μτh = 4- 6×10-5 cm2/V) for CdTe and CZT, respectively. Detectors in single pixel, Frisch collar, and coplanar grid geometries were fabricated. Detectors in Frisch grid and guard-ring configuration were found to exhibit energy resolution of 1.4% and 2.6 %, respectively, for 662 keV gamma rays. Assessments of the detector performance have been carried out also using 241Am (60 keV) showing energy resolution of 4.2% FWHM.

Paper Details

Date Published: 17 September 2014
PDF: 9 pages
Proc. SPIE 9213, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVI, 92131L (17 September 2014); doi: 10.1117/12.2063054
Show Author Affiliations
Krishna C. Mandal, Univ. of South Carolina (United States)
Ramesh M. Krishna, Univ. of South Carolina (United States)
Rahmi O. Pak, Univ. of South Carolina (United States)
Mohammad A. Mannan, Univ. of South Carolina (United States)

Published in SPIE Proceedings Vol. 9213:
Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVI
Arnold Burger; Larry Franks; Ralph B. James; Michael Fiederle, Editor(s)

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