Single charge carrier type sensing with a parallel strip pseudo-Frisch-grid CdZnTe semiconductor radiation detector

McGregor, Douglas S.; He, Zhong; Seifert, H.; Wehe, D.K.; Rojeski, Ronald A.

doi:10.1063/1.120895

Cited by 91 publications

(33 citation statements)

References 14 publications

(11 reference statements)

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“…The potential of CdZnTe has been demonstrated through many material and detector technology developments over the last decade. [1][2][3][4][5][6][7][8][9][10][11][12][13] The material has the desirable intrinsic properties of a wide bandgap necessary for room-temperature operation and a high average atomic number for efficient gamma-ray stopping. Furthermore, the CdZnTe material that is commercially available today exhibits negligible polarization effects, has a high bulk resistivity, and has reasonably good electron collection properties.…”

Section: Introductionmentioning

confidence: 99%

Electron trapping nonuniformity in high-pressure-Bridgman-grown CdZnTe

Amman

Lee

Luke

2002

Journal of Applied Physics

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Gamma-ray spectroscopy is a valuable tool of science and technology. Many applications for this tool are in need of a detector technology capable of achieving excellent energy resolution and efficient detection while operating at room temperature. Detectors based on the material cadmium zinc telluride (CdZnTe) could potentially meet this need if certain material deficiencies are addressed. The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. At the present time, the performance of these detectors is mainly limited by the degree of uniformity in electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alphaparticle response characterization of CdZnTe crystals fabricated into simple planar detectors provides an effective tool to accurately study such variations. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. For a number of crystals, a clear correlation has been observed between their alpha response maps and the distribution of tellurium inclusions inside the crystals. An analysis of the induced charge signals indicates that regions of enhanced electron trapping are associated with the inclusions, and that these regions extend beyond the physical size of the inclusions. Such regions introduce non-uniform electron trapping in the material that then degrades the spectroscopic performance of the material as a gamma-ray detector.2

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Section: Introductionmentioning

confidence: 99%

Electron trapping nonuniformity in high-pressure-Bridgman-grown CdZnTe

Amman

Lee

Luke

2002

Journal of Applied Physics

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“…This approach allows one to assemble large area/volume detectors by using easy-to-produce and relatively inexpensive CZT crystals. The first such semiconductor detector was presented as a simple semiconductor bar with side conductive strips acting as the Frisch grid [15]. A variety of permutations on the previous design have been proposed and tested, including a concept of the most practical capacitive Frisch-grid device [16].…”

Section: Virtual Frisch-grid Devicesmentioning

confidence: 99%

Large area/volume CZT nuclear detectors

Bolotnikov

Camarda

Carini

et al. 2005

phys. stat. sol. (c)

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PACS 29.40.Wk Cadmium zinc telluride (CZT) is one of the most promising materials for large-volume gamma-ray spectrometers and imaging arrays. However, because of deficiencies in the high quality material, highresolution CZT spectrometers are still limited to relatively small dimensions (< 2-3 cm 3 ), which make them inefficient at detecting gamma rays. To extend the range of CZT detector applications, an increase in their efficiency is needed without sacrificing the ability to spectrally resolve gamma energies. Achieving this goal requires progress in the growth of large uniform single crystals, reductions in carrier trapping, increases in electrical resistivity, and improved device fabrication procedures. This paper summarizes the current developments in large area/volume CZT detectors and the common constraints on their designs: bulk and surface leakage currents, charge sharing and loss in multi-electrode devices, and charge transport non-uniformities. We also describe recent progress in characterization of CZT materials and devices using new capabilities at Brookhaven National Laboratory. 1 Introduction Semi-insulating crystals of cadmium zinc telluride (for zinc concentrations in the range of 0-20%) have shown great potential for the production of room temperature X-and gamma-ray detectors and imaging cameras. The combination of high efficiency and good energy resolution makes these detectors attractive for a diverse range of applications, including gamma-ray spectroscopy, nuclear safeguards, X-ray fluorescence, environmental cleanup, astronomy, bone scans, detection of tumors and other abnormalities, and diagnosis of heart disease. Thus far, the size of the detectors produced from CZT crystals has been limited to only a few cubic centimeters due to the low yield of large uniform crystals with suitable material properties. The low yields have resulted in relatively high cost for detectors, which has prevented the use of the technology in many applications. The problem of high cost is compounded by the electronic trapping in the crystals, which causes the energy resolution to be less than desired, particularly for large area/volume devices. To compensate for the carrier trapping and accompanied loss of energy resolution, single carrier devices and customized pulse-processing electronics have been developed. Although further improvements in the crystal growth are required for many large area/volume applications, the performance of CZT devices, the global capacity for growth of detectorgrade crystals, and the size of the commercial market have progressed steadily.

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“…For the Frisch collar mode, each crystal was wrapped in two layers of thin teflon tape, covering the full height, leaving out anode and cathode, similar to devices fabricated in [2]. The teflon layer was wrapped in a metal foil (aluminium kitchen foil worked best for us) and the foil attached via a small 'lip' to the cathode (using silver conductive paint).…”

Section: Methodsmentioning

confidence: 99%

“…Already the reduction of wiring close to the crystals by a factor of two would be highly significant in this case. Frisch collar detectors [2] appeared to be the most practical way forward, so we modified three existing coplanar grid crystals, low-grade from eV-Products 1 . In order to have a standard to compare with, we purchased one eV-CAPture Plus technology detector which is of much higher quality [3].…”

Section: Introductionmentioning

confidence: 99%

Energy resolution improvement in room-temperature CZT detectors

Ramachers

Stewart

2007

J. Inst.

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We present methods to improve the energy resolution of single channel, room-temperature Cadmium-Zinc-Telluride (CZT) detectors. A new preamplifier design enables the acquisition of the actual transient current from the crystals and straightforward data analysis methods yield unprecedented energy resolution for our test-detectors. These consist of an eVCAPture Plus crystal as standard and 1 cm cube Frisch collar crystals created in-house from low-grade coplanar grid detectors. Energy resolutions of 1.9% for our collar detectors and 0.8% for the eV crystal at 662 keV were obtained. The latter compares favourably to the best existing energy resolution results from pixel detectors.

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Single charge carrier type sensing with a parallel strip pseudo-Frisch-grid CdZnTe semiconductor radiation detector

Cited by 91 publications

References 14 publications

Electron trapping nonuniformity in high-pressure-Bridgman-grown CdZnTe

Electron trapping nonuniformity in high-pressure-Bridgman-grown CdZnTe

Large area/volume CZT nuclear detectors

Energy resolution improvement in room-temperature CZT detectors

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