Defects in CZT crystals and their relationship to gamma-ray detector performance

Bürger, A.; Chattopadhyay, K.; Chen, H; Ma, Xiangyun; Ndap, J.-O.; Schieber, M.; Schlesinger, T. E.; Yao, H. Walter; Erickson, Jay C.; James, R. B.

doi:10.1016/s0168-9002(00)00294-1

Cited by 28 publications

(16 citation statements)

References 15 publications

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“…In high-quality detectors, small defects are less likely to cause a large loss in performance when a large area of the crystal is being used as the detector. However, when high-spatial-resolution gamma detection is desired even small defects cause a noticeable decrease in performance [14][15][16][18][19]. A common defect found in most high-quality CZT crystals is Te secondary phases, often located along grain boundaries [13,16,19,24,25].…”

Section: Introductionmentioning

confidence: 99%

Synchrotron radiation x-ray absorption fine-structure and Raman studies on CdZnTe ternary alloys

Chen

Feng

et al. 2009

SPIE Proceedings

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The synchrotron radiation (SR) X-ray absorption fine-structure spectroscopy (XAFS) technology has been employed to obtained Zn K-edge absorption spectra for Cd 1−x Zn x Te alloy with x = 0.03, 0.10, 0.20, 0.30, 0.40, 0.50 and 1.00. Their Fourier transform spectra were analyzed, which have shown a bimodal distribution of bond lengths, suggesting distortion of the Te sub-lattice, so that the linear interpolation is true only in an approximate sense. Synthetic CdZnTe crystals can be used for the room temperature-based detection of gamma radiation. The radiation detection properties of CZT crystals vary widely. A common defect found in most high-quality CZT crystals is Te secondary phases, often located along grain boundaries. The secondary phases can be both large inclusions (>50 μm) and smaller precipitates (<50 μm). The Te secondary phases distributed throughout the crystal can cause changes to the detector leakage current, resulting in decreased radiation spectrometer performance. This set of Cd 1-x Zn x Te crystals were also measured by Raman scattering at room temperature. The two observed peaks at about 125 and 145 cm -1 which can be assigned to Te A 1 and E phonon mode, respectively. The induced damage on the crystal surfaces by Raman laser has been discussed. It is suggested that in the case of highly Zn doping CdZnTe crystals, the ZnTe bond were broken by laser exposing and then free Te atoms are migrating to these heated areas which cause Te precipitate. Further, the results of the soft X-ray measurements have been also presented and this part of the experimental data needs to do more penetrating analysis in the future.

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Section: Introductionmentioning

confidence: 99%

Synchrotron radiation x-ray absorption fine-structure and Raman studies on CdZnTe ternary alloys

Chen

Feng

et al. 2009

SPIE Proceedings

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“…However, the performance of the detector increased slightly on lowering the temperature below room temperature, consistent with literature reports. 4 Based on our data, we conclude that an increase in temperature adversely affects detector performance to well below an acceptable level, and our results demonstrate that CZT detector materials must be kept at 25°C or cooler to achieve optimum performance.…”

Section: Atmospheric Effectsmentioning

confidence: 59%

“…Recent progress has been made to improve material development and, in some cases, has refined the research focus for making and studying these types of materials. 3,4 For example, problems with defects such as pipes have been resolved; however, defects which occupy smaller crystal volumes such as secondary phases (SP) are presently one of the major concerns with regard to gamma spectrometer performance, as discussed and reviewed by Duff et al 5 The environmental operating conditions for CZT detectors have mostly been overlooked in terms of understanding overall detector performance. Roomtemperature detection of gamma and x-ray radiation encompasses a range of atmospheric conditions, so there is a need to understand performance under such conditions.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Effects on the Performance of CdZnTe Single-Crystal Detectors

Washington

Teague²,

Duff

et al. 2010

Journal of Elec Materi

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The production of high-quality ternary single-crystal materials for radiation detectors has progressed over the past 15 years. One of the more common materials being studied is CdZnTe (CZT), which can be grown using several methods to produce detector-grade materials. The work presented herein examines the effects of environmental conditions including temperature and humidity on detector performance [full-width at half-maximum (FWHM)] using the single pixel with guard detector configuration. The effects of electrical probe placement, reproducibility, and aging are also presented.

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“…CZT crystals have great potential for use in room-temperature gamma and X-ray spectrometers [1][2][3][4][5][6][7][8][9] . They can be grown with high purity starting materials, thus limiting the defects present in the crystal due to impurities.…”

Section: Introductionmentioning

confidence: 99%

“…Characterization techniques include infrared (IR) transmission imaging, synchrotron X-ray topography, photoluminescence spectroscopy, Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Raman spectroscopy. All of these methods have been used to test for quality and/or to predict performance of the crystal as a gamma-ray detector [1][2][3][4][5][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] . The availability of multiple techniques will help to validate a crystal's quality and its ability to be used for either qualitative or quantitative gamma-ray or X-ray detection.…”

Section: Introductionmentioning

confidence: 99%

AFM characterization of laser-induced damage on CdZnTe crystal surfaces

Hawkins¹,

Teague²,

Villa‐Aleman³

et al. 2008

SPIE Proceedings

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Semi-conducting CdZnTe (or CZT) crystals can be used in a variety of detector-type applications. CZT shows great promise for use as a gamma radiation spectrometer. However, its performance is adversely affected by point defects, structural and compositional heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), secondary phases and in some cases, damage caused by external forces. One example is damage that occurs during characterization of the surface by a laser during Raman spectroscopy. Even minimal laser power can cause Te enriched areas on the surface to appear. The Raman spectra resulting from measurements at moderate intensity laser power show large increases in peak intensity that is attributed to Te. Atomic Force Microscopy (AFM) was used to characterize the extent of damage to the CZT crystal surface following exposure to the Raman laser. AFM data reveal localized surface damage in the areas exposed to the Raman laser beam. The degree of surface damage to the crystal is dependent on the laser power, with the most observable damage occurring at high laser power. Moreover,

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Defects in CZT crystals and their relationship to gamma-ray detector performance

Cited by 28 publications

References 15 publications

Synchrotron radiation x-ray absorption fine-structure and Raman studies on CdZnTe ternary alloys

Synchrotron radiation x-ray absorption fine-structure and Raman studies on CdZnTe ternary alloys

Atmospheric Effects on the Performance of CdZnTe Single-Crystal Detectors

AFM characterization of laser-induced damage on CdZnTe crystal surfaces

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