Electrode design for coplanar-grid detectors

Luke, P.N.; Amman, M.; Prettyman, T. H.; Russo, P.A.; Close, D.A.

doi:10.1109/23.603739

Cited by 29 publications

(19 citation statements)

References 5 publications

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“…The coplanar-grid pattern was designed for charge induction uniformity using three-dimensional electrostatic modeling and then later tested for uniformity through alpha-particle scanning measurements. 15,16,18 The completed coplanar-grid detector is placed inside a test chamber where it is illuminated with gamma rays from a 137 Cs source and operated as a differential-gain coplanar-grid detector. 16 The operating conditions of the detector are then optimized in order to produce the best possible 662 keV gamma-ray peak resolution.…”

Section: Characterization Proceduresmentioning

confidence: 99%

“…One of these electron-only approaches is the coplanar-grid charge-sensing technique. 5 This technique and its variations offer the advantages of nearly eliminating the hole collection problem, providing accurate and adjustable correction for electron trapping, producing uniform charge induction, 15,16 realizing near full-volume detection efficiency, 17,18 and requiring only simple conventional pulse-processing electronics. Coplanar-grid detectors 1cm 3 in size have achieved energy resolutions down to about 2% FWHM at 662keV, and hand-held systems have been produced from such detectors.…”

Section: Introductionmentioning

confidence: 99%

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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: Characterization Proceduresmentioning

confidence: 99%

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 is due to the asymmetry of the internal potential fields, and this is a known effect that can be eliminated by carefully desi=ting the grid spacing, pitch, and symmetry [16].…”

Section: Va the Total Internal Electrostatic Potentialmentioning

confidence: 99%

Effect of electron transport properties on unipolar CdZnTe radiation detectors: LUND, spectrumplus and coplanar grid

Lee

James

1999

Journal of Elec Materi

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Device simulations of(1) the laterally-contacted-fipo~aI-nuc~em detector (LUND), (2) the SpectrumPlus, (3) and the coplanar grid made of CdO.gZM.ITe (CZT)were performed for 'S7CSirradiation by 662.15 keV gamma-rays. Realistic and controlled simulations of the gamma-ray interactions with the CZT material were done using the MCNP4B2 Monte Carlo program, and the detector responses were simulated using the Sandia three-dimensional multielectrode simulation program (SandTMSP).The simulations were done for the best and the worst expected carrier nobilities and lifetimes of currently commercially available CZT materiaIs for radiation detector applications-For the simulated unipolar devices, the active device volumes were relatively large and the ener~q resolutions were fairly good, but these performance characteristics were found to be very sensitive to the materials properties. The internal electric fields, the weighting potentials, and the charge induced efficiency maps were calculated to give insights into the operation of these devicesTbe snbmittd mannaoript h k authored by a contractor of i&e un~ed States Government under contiad. Accordingly the Lkited States Gov. emment retains a non. excl~i~, royalty-free license to publish or re. produce the published form of this contribution, or aIlow others to do SO, for United Statea Gov~~t ppeeea.,- L IntroductionTheunipol= mdiation detectors madeofsemi-insulating C&.gZm.lTe (CZT),2] have recently received much attention, due to their potential for improved gma-ray detection sensitivi~andenergy resolution [3][4][5][6]. Because theeIectron rnobilities are -20 times larger than the hole nobilities and because the electron lifetimes are at least -10 times longer than the hole lifetimes in these materials [7,8], these unipolar devices are designed to depend only on the electron's transport properties.However, because of the unknown variation in the starting detector materials, the high cost of materials and fabrication, and the relatively complex geometries and operating conditions that are characteristic of these unipolar detector designs, quantitative experimental determination of their active volume and energy resolution are typically extremely difilcult. And it is just as difficult to determine how robust these perfommnce to these difficult tasks is to use validated computer programs for the characteristics are with respect to the inevitable variation of the of the carrier transpofi properties.A solution simulation of these devices. A device simulation can give the total control of the device and materials parameters and, in addition, it can allow the examination of all device finctions. We have performed device simulations of three recendy deveIoped unipolar detectors made of Cc&.gZnO.lTe:(1) the laterally-contacted-unipolar-nuclear detector (LUND) [Ref. 3,41,(2) DISCLAIMERPortions of this document may be illegible in electronic image products.Images are produced from the best available original document.was used for realistic and controlled interaction of gamma...

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“…One of these electron-only approaches is the coplanar-grid charge-sensing technique. 4 This technique and its variations offer the advantages of nearly eliminating the hole collection problem, providing accurate and adjustable correction for electron trapping, producing uniform charge induction, 12,13 realizing near full-volume detection efficiency, 14,15 and requiring only simple conventional pulse-processing electronics. Coplanar-grid detectors 1cm 3 in size have achieved energy resolutions down to about 2% FWHM at 662keV, and complete hand-held detection systems have been produced from such detectors.…”

Section: Introductionmentioning

confidence: 99%

<title>Alpha particle response characterization of CdZnTe</title>

2001

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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. The performance of these detectors is limited by the degree of uniformity in both 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. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance.

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Electrode design for coplanar-grid detectors

Cited by 29 publications

References 5 publications

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

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

Effect of electron transport properties on unipolar CdZnTe radiation detectors: LUND, spectrumplus and coplanar grid

<title>Alpha particle response characterization of CdZnTe</title>

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