Three-Dimensional Position-Sensitive Germanium Detectors

Amman, M.; Luke, P.N.

doi:10.2172/833168

Cited by 2 publications

(6 citation statements)

References 25 publications

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“…To address these concerns, we have conducted several experiments, all of which validate the use of the technique, at least for HPB CdZnTe material produced by eV Products and processed using the method described above. As reported previously, 24 the results of these experiments clearly indicate that the non-uniformity we observe using alpha-particles is due to bulk material effects, not contact or near-contact effects. However, it is important to note that the technique may not be as useful for other materials and/or fabrication processes.…”

Section: Characterization Proceduressupporting

confidence: 89%

“…Non-uniformities apparently not explainable through simple mobility-field changes were also identified in previous studies. 23,24 The more severe of these were observed to have substantial variations over small length scales (less than 1 mm), and crystals with this problem were found to perform poorly as coplanar-grid detectors. In an effort to understand the nature of these and other non-uniformities, we have attempted to correlate the spatial dependence of the alpha response with spatial variations of other material properties.…”

Section: Resultsmentioning

confidence: 99%

“…When an Imarad crystal was processed as described in this section, a contact thickness measurement gave an anomalous result. 24 A comparison of the collected charge from an alpha interaction event in that same crystal to that of a low-energy gamma ray indicated a significant charge collection deficit for the case of the alpha event. From these measurements, we conclude that the alpha characterization technique does not appear to be an appropriate tool to analyze the uniformity of this material, and a more appropriate choice might be low-energy gamma rays.…”

Section: Characterization Proceduresmentioning

confidence: 99%

“…[22][23][24] In one such method, an alpha-particle source is used to probe the cathode side of a CdZnTe crystal that has been fabricated into a simple planar detector. Each alpha-particle interaction event in the detector generates a well-defined number of electron-hole pairs near the cathode.…”

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 Proceduressupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Characterization Proceduresmentioning

confidence: 99%

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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“…21 There is significant evidence that Te inclusions and the surrounding defect field have a strong detrimental effect on electron transport in CdZnTe crystals and poor performance of the fabricated detector devices. 22,23 It was also shown that the region of degraded charge transport near Te inclusions extend well beyond the volume of the inclusions themselves. This might be due to the field of dislocations and Te precipitates surrounding Te inclusions.…”

Section: Structural Propertiesmentioning

confidence: 98%

Advances in the high-pressure crystal growth technology of semi-insulating CdZnTe for radiation detector applications

et al. 2004

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The properties of large diameter (140 mm) semi-insulating Cd 1-x Zn x Te (x = 0.1) ingots grown by the vertical High-Pressure Electro-Dynamic Gradient (HP EDG) technique are discussed. The HP EDG crystal growth technology recently developed and introduced at eV PRODUCTS significantly improves the downstream CdZnTe detector fabrication yield compared to earlier versions of the HP crystal growth technology. These yield improvements stem from the improved structural and charge transport properties of the HP EDG CdZnTe ingots. Improvements were achieved in three areas: a) reduced thermal stress in the ingots, b) improved single crystal yield, and c) improved electron transport properties. The new state-of-the-art HP EDG crystal growth systems offer exceptional flexibility, thermal and mechanical stability and allow the growth of high purity CdZnTe materials. The flexibility of the multi-zone heater system allows the dynamic control of heat flow to optimize the growth-interface shape during crystallization. This flexibility combined with an advanced control system, improved system diagnostics and realistic thermal modeling provides an excellent platform for further process development. Results on the initial HP EDG CdZnTe ingots grown with low temperature gradient show the complete elimination of ingot cracking. The increased single crystal yield combined with the improved electron transport properties allows the fabrication of largevolume electron-only devices at higher yield. The CdZnTe ingots regularly contain sections with electron mobility-lifetime product e 5.0 10 -3 cm 2 /V and occasionally yield material with e 8.0 10 -3 cm 2 /V.

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Three-Dimensional Position-Sensitive Germanium Detectors

Cited by 2 publications

References 25 publications

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

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

Advances in the high-pressure crystal growth technology of semi-insulating CdZnTe for radiation detector applications

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