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Title: Effect of Te precipitates on the performance of CdZnTe detectors

Abstract

Measurements using the National Synchrotron Light Source provided a detailed comparisons of the microscale detector response and infrared microscopy images for CdZnTe Frisch-ring x-ray and gamma detectors. Analysis of the data showed conclusively that local deteriorations of the electron charge collection and x-ray device response fully correlate with the presence of Te precipitates as seen in the IR images. Effects of the surface processing conditions on the detector performance were also clearly observed.

Authors:
; ; ; ; ;  [1];  [2]
  1. Department of Nonproliferation and National Security, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20779170
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 88; Journal Issue: 14; Other Information: DOI: 10.1063/1.2189912; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; CADMIUM TELLURIDES; CHARGE COLLECTION; ELECTRONS; GAMMA DETECTION; IMAGES; MICROSCOPY; NSLS; PERFORMANCE; PRECIPITATION; SEMICONDUCTOR DETECTORS; SEMICONDUCTOR MATERIALS; SURFACE TREATMENTS; TELLURIUM; X-RAY DETECTION; ZINC TELLURIDES

Citation Formats

Carini, G.A., Bolotnikov, A.E., Camarda, G.S., Wright, G.W., James, R.B., Li, L., and Yinnel Tech, Inc., South Bend, Indiana 46619. Effect of Te precipitates on the performance of CdZnTe detectors. United States: N. p., 2006. Web. doi:10.1063/1.2189912.
Carini, G.A., Bolotnikov, A.E., Camarda, G.S., Wright, G.W., James, R.B., Li, L., & Yinnel Tech, Inc., South Bend, Indiana 46619. Effect of Te precipitates on the performance of CdZnTe detectors. United States. doi:10.1063/1.2189912.
Carini, G.A., Bolotnikov, A.E., Camarda, G.S., Wright, G.W., James, R.B., Li, L., and Yinnel Tech, Inc., South Bend, Indiana 46619. Mon . "Effect of Te precipitates on the performance of CdZnTe detectors". United States. doi:10.1063/1.2189912.
@article{osti_20779170,
title = {Effect of Te precipitates on the performance of CdZnTe detectors},
author = {Carini, G.A. and Bolotnikov, A.E. and Camarda, G.S. and Wright, G.W. and James, R.B. and Li, L. and Yinnel Tech, Inc., South Bend, Indiana 46619},
abstractNote = {Measurements using the National Synchrotron Light Source provided a detailed comparisons of the microscale detector response and infrared microscopy images for CdZnTe Frisch-ring x-ray and gamma detectors. Analysis of the data showed conclusively that local deteriorations of the electron charge collection and x-ray device response fully correlate with the presence of Te precipitates as seen in the IR images. Effects of the surface processing conditions on the detector performance were also clearly observed.},
doi = {10.1063/1.2189912},
journal = {Applied Physics Letters},
number = 14,
volume = 88,
place = {United States},
year = {Mon Apr 03 00:00:00 EDT 2006},
month = {Mon Apr 03 00:00:00 EDT 2006}
}
  • A recent study of long-drift CdZnTe (CZT) Frisch-ring detectors showed that fluctuations of the collected charge (and device response) depend on the device dimensions and the concentration of Te precipitates in the material. This observation, which could be explained as the cumulative effect of precipitates, led to the investigation of thin (1 mm) planar detectors, where the effects of precipitates can be more clearly ascertained. To perform the investigation, a measurement facility was developed that allowed for high-resolution spatial mapping of the performance of CZT devices. New measurements emerging from this facility provided the first detailed comparisons of the micro-scalemore » X-ray maps and infrared microscopy images for thin CZT samples. Analysis of the data showed conclusively that local deteriorations of device response fully correlate with Te precipitates seen in the IR images. Effects of surface processing conditions on the detector response were also clearly observed.« less
  • Te inclusions existing at high concentrations in CdZnTe (CZT) material can degrade the performance of CZT detectors. These microscopic defects trap the free electrons generated by incident radiation, so entailing significant fluctuations in the total collected charge and thereby strongly affecting the energy resolution of thick (long-drift) detectors. Such effects were demonstrated in thin planar detectors, and, in many cases, they proved to be the dominant cause of the low performance of thick detectors, wherein the fluctuations in the charge losses accumulate along the charge's drift path. We continued studying this effect using different tools and techniques. We employed amore » dedicated beamline recently established at BNL's National Synchrotron Light Source for characterizing semiconductor radiation detectors, along with an IR transmission microscope system, the combination of which allowed us to correlate the concentration of defects with the devices' performances. We present here our new results from testing over 50 CZT samples grown by different techniques. Our goals are to establish tolerable limits on the size and concentrations of these detrimental Te inclusions in CZT material, and to provide feedback to crystal growers to reduce their numbers in the material.« less
  • In this paper, homogenization theory based on a multiple scale perturbation of the charge-transport equation is used to derive a mathematical framework for modeling the cumulative effect of Te inclusions in radiation detectors based on semi-insulating cadmium zinc telluride (CdZnTe). The derived framework naturally incorporates a wide range of physical models that may posit either a reduced electron lifetime due to enhanced trapping at inclusions, or an altered carrier speed due to a distorted electric field at inclusions, or both. The new framework is applied to a simplified version of the geometric model introduced by Bolotnikov et al. [Nucl. Instrum.more » Methods Phys. Res. A 571, 687 (2007)], and it is shown that this results in a closed-form approximation to the reduced electron trapping time that depends in a rather simple way on fundamental inclusion parameters such as their mean size and number density. It is also demonstrated that this effective trapping time compares well with previously published simulation data for the geometric model. Further, the electron mobility-lifetime product that results from the reduced carrier lifetime is easily incorporated into Monte Carlo device simulation. Examples of simulated induction maps and pulse-height spectra for pixelated detectors that contain inclusions of various mean sizes and number densities are presented.« less