Carbon Coating and Defects in CdZnTe and CdMnTe Nuclear Detectors

Egarievwe, Stephen U.; Chan, Wing; Kim, Ki‐Hyun; Roy, Utpal; Sams, Valissa; Hossain, Anwar; Kassu, Aschalew; James, R. B.

doi:10.1109/tns.2016.2515108

Cited by 33 publications

(15 citation statements)

References 35 publications

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“…Detector-grade CdMnTe and CdZnTe wafers are expected to have resistivity of the order of 10 12 -cm. The resistivity of CdMnTe crystals could be increased during crystal growth by doping the material with indium [1]. The problem of reduction in resistivity after annealing CdZnTe in Cd vapor could be resolved by annealing in a combination of Cd-rich and Zn-rich atmosphere [15].…”

Section: Discussionmentioning

confidence: 99%

“…This gives them the advantages of reduced operation cost and fabrication of portable and hand-held devices for the detection of X-rays and gamma-rays. CdTe and CdZnTe are commercially available [1]- [4], but the cost of their production is very high due to low growth yields of crystals with a high-resistivity, less defects and high-intrinsic efficiency. Recently, researchers have been investigating cadmium manganese telluride (CdMnTe) for room-temperature nuclear and radiological detection applications [5]- [10].…”

Section: Introductionmentioning

confidence: 99%

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Thermal Annealing of CdMnTe Material Being Developed for Nuclear Radiation Detection Applications

Adams¹,

Agbalagba²,

Jow³

et al. 2016

IOSR

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Cadmium manganese telluride (CdMnTe) is one of the semiconductor materials with potential applications at room-temperature for nuclear and radiological detection. CdMnTe crystals grown by Bridgman technique are prone to tellurium inclusions and related defects that limit their performance as X-rays and gamma-rays detectors. The major reason for this is that they are grown in a tellurium-rich environment. These defects could trap charges that are generated by X-rays and gamma rays thereby degrading the charge transport properties of the detectors and reducing their carrier lifetime. This in turn leads to poor performance by the detector. One of the solutions to this problem is post-growth thermal annealing. In this paper we present experimental results of annealing a CdMnTe wafer at 720 o C and in cadmium vapor. The CdMnTe wafer and cadmium were sealed in a quartz ampoule at a vacuum of 10-5 mbar. We used a three-zone furnace that enabled us to adjust the three heating elements to get a flat region of 720 o C in the temperature profile where the wafer was annealed. Infrared transmission microscopy showed changes to the sizes and positions of the tellurium inclusions. There are reductions in the dimensions of the medium-size Te inclusions. Some Te inclusions were completely eliminated while others broke up to form much smaller inclusions. Current-voltage measurements showed that the resistivity of the CdMnTe wafer was reduced by 71 %, from 2.44 x 10 5 -cm to 7.17 x 10 4 -cm after annealing in Cd vapor.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal Annealing of CdMnTe Material Being Developed for Nuclear Radiation Detection Applications

Adams¹,

Agbalagba²,

Jow³

et al. 2016

IOSR

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“…The ability to operate at room temperature without cryogenic cooling has made cadmium zinc telluride (CdZnTe) nuclear detectors popular in X-ray detection and gamma-ray spectroscopy applications [1] [2] [3] [4] [5]. The absence of the need to cool the detector gives the advantage of reduced operational costs and the production of hand-held devices, when compared to detectors that need cooling, such as germanium-based detectors.…”

Section: Introductionmentioning

confidence: 99%

Study of Chemical Etching and Chemo-Mechanical Polishing on CdZnTe Nuclear Detectors

Adams¹,

Egarievwe²,

Agbalagba³

et al. 2019

MSCE

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Cadmium zinc telluride (CdZnTe) semiconductor has applications in the detection of X-rays and gamma-rays at room temperature without having to use a cooling system. Chemical etching and chemo-mechanical polishing are processes used to smoothen CdZnTe wafer during detector device fabrication. These processes reduce surface damages left after polishing the wafers. In this paper, we compare the effects of etching and chemo-mechanical polishing on CdZnTe nuclear detectors, using a solution of hydrogen bromide in hydrogen peroxide and ethylene glycol mixture. X-ray photoelectron spectroscopy (XPS) was used to monitor TeO 2 on the wafer surfaces. Currentvoltage and detector-response measurements were made to study the electrical properties and energy resolution. XPS results showed that the chemical etching process resulted in the formation of more TeO 2 on the detector surfaces compared to chemo-mechanical polishing. The electrical resistivity of the detector is of the order of 10 10 Ω-cm. The chemo-mechanical polishing process increased the leakage current more that chemical etching. For freshly treated surfaces, the etching process is more detrimental to the energy resolution compared to chemo-mechanically polishing.

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“…ating at room temperature without cryogenic cooling [1] [2] [3]. The CdZnTe crystals are grown under tellurium-rich environments to attain high resistivity that is needed for the detector to operate at room temperature [4].…”

mentioning

confidence: 99%

“…The CdZnTe crystals are grown under tellurium-rich environments to attain high resistivity that is needed for the detector to operate at room temperature [4]. The major requirements need for detectors to operate at room temperature include high atomic number, large energy band gap, high density, and high electrical resistivity [2] [3]. The average atomic number of CdZnTe is (48 for Cd, 30 for Zn, and 52 for Te) high enough for room-temperature detector operation [3].…”

mentioning

confidence: 99%

Analysis of Te and TeO<sub>2</sub> on CdZnTe Nuclear Detectors Treated with Hydrogen Bromide and Ammonium-Based Solutions

Drabo¹,

Egarievwe²,

Okwechime³

et al. 2017

MSCE

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Surface defects caused during cutting and polishing in the fabrication of cadmium zinc telluride (CdZnTe) nuclear detectors limit their spectral performance. Chemical treatments are often used to remove surface damages and defects. In this paper, we present the analysis of Te and TeO 2 species on the surfaces of CdZnTe nuclear detectors treated with hydrogen bromide and ammonium-based solutions. The CdZnTe wafers were chemo-mechanically polished in a mixture of hydrogen bromide in hydrogen peroxide and ethylene glycol, followed by a chemical passivation in a mixture of ammonium fluoride and hydrogen peroxide solution. X-ray photoelectron spectroscopy showed significant conversion of Te to TeO 2 , thus producing a more chemically stable surface. The resistivity of the CdZnTe samples is in the order of 10 10 ohms-cm. The current for a given applied voltage increased following the passivation and decreased after a 3-hour period. Results from spectral response measurements showed that the 59.5-keV gamma-peak of Am-241 was stable under the same channel for the surface treatment processes.

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Carbon Coating and Defects in CdZnTe and CdMnTe Nuclear Detectors

Cited by 33 publications

References 35 publications

Thermal Annealing of CdMnTe Material Being Developed for Nuclear Radiation Detection Applications

Thermal Annealing of CdMnTe Material Being Developed for Nuclear Radiation Detection Applications

Study of Chemical Etching and Chemo-Mechanical Polishing on CdZnTe Nuclear Detectors

Analysis of Te and TeO<sub>2</sub> on CdZnTe Nuclear Detectors Treated with Hydrogen Bromide and Ammonium-Based Solutions

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Carbon Coating and Defects in CdZnTe and CdMnTe Nuclear Detectors

Cited by 33 publications

References 35 publications

Thermal Annealing of CdMnTe Material Being Developed for Nuclear Radiation Detection Applications

Thermal Annealing of CdMnTe Material Being Developed for Nuclear Radiation Detection Applications

Study of Chemical Etching and Chemo-Mechanical Polishing on CdZnTe Nuclear Detectors

Analysis of Te and TeO&lt;sub&gt;2&lt;/sub&gt; on CdZnTe Nuclear Detectors Treated with Hydrogen Bromide and Ammonium-Based Solutions

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Analysis of Te and TeO<sub>2</sub> on CdZnTe Nuclear Detectors Treated with Hydrogen Bromide and Ammonium-Based Solutions