Characteristics of X-ray and gamma radiation detectors based on polycrystalline CdTe and CdZnTe films

Based on CdTe and CdZnTe detectors a number of promising devices were created, which found their application in metallurgy, in solving the problems of customs control and control of nuclear materials, as well as matrix detectors created for the manufacture of medical devices and devices for space research. Detectors, created on the basis of polycrystalline semiconductor CdTe and CdZnTe films with a columnar structure on a molybdenum substrate with a thickness d = 30150 μm, had a specific resistance p > 10^5 10^8 W-cm. The energy resolution of the CdTe and CdZnTe detectors at room temperature reached ~ 5 keV on the 59.6 keV 241Am line.

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Synthesis and Characterisation of Thin Films of Bismuth Triiodide for Semiconductor Radiation Detectors

Conference Papers in Science ◽

10.1155/2014/370436 ◽

2014 ◽

Vol 2014 ◽

pp. 1-3 ◽

Cited By ~ 6

Author(s):

Alka Garg ◽

Monika Tomar ◽

Vinay Gupta

Keyword(s):

Thin Films ◽

Absorption Coefficient ◽

Room Temperature ◽

Active Material ◽

Visible Region ◽

Radiation Detectors ◽

Radiation Absorption ◽

X Rays ◽

X Ray ◽

Bismuth Iodide

Bismuth iodide is a potentially active material for room temperature radiation detector, as it is well reported in the literature that it has both wide energy band gap and high atomic absorption coefficient. Crystalline films of high atomic number and high radiation absorption coefficient can absorb the X-rays and convert them directly into electrical charges which can be read by imaging devices. Therefore, it was proposed to grow thin films of Bismuth iodide on glass substrate using thermal evaporation technique in vacuum to avoid the inclusion of impurities in the films. The structural studies of the films were carried out using XRD and optical absorption measurement was carried out in the UV/VIS region using spectrophotometer. All Bismuth iodide films grown at room temperature are polycrystalline and show X-ray diffraction peaks at angles reported in research papers. The optical transmission spectra of BiI3 films show a high transmission of about 80% in visible region with a sharp fall near the fundamental absorption at 650 nm. Resistivity of the as-grown film was found to be around 1012 ohm-cm suitable value for X-ray detection application. Films were subjected to scanning electron microscopy to study the growth features of both as-grown and annealed films.

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The Fabrication of Mercuric Iodide Detectors for Use in Wavelength Dispersive X-Ray Analysers and Backscatter Photon Measurements

MRS Proceedings ◽

10.1557/proc-16-207 ◽

1982 ◽

Vol 16 ◽

Cited By ~ 10

Author(s):

John H. Howes ◽

John Watling

Keyword(s):

Room Temperature ◽

Gamma Ray ◽

Surface Passivation ◽

Electrical Contact ◽

Scintillation Counter ◽

Radiation Detectors ◽

Nuclear Radiation ◽

Gamma Ray Spectrometry ◽

Mercuric Iodide ◽

X Ray

ABSTRACTThis paper describes the fabrication of mercuric iodide nuclear radiation detectors suitable for X and gamma ray spectrometry at room temperature. The active area of the detectors studied are between 0.2 and 1.5cm sq and they are up to 0.5mm thick. The method of producing a stable electrical contact to the crystal using sputtered germanium has been studied. The X-ray resolution of a 1.5cm sq. area detector at 32 keV is 2.3 keV FWHM when operated at room temperature in conjunction with a time variant filter amplifier. A factor which is important in the fabrication of the detector is the surface passivation necessary to achieve a useful detector life.This type of detector has been used on a wavelength dispersive X-ray spectrometer for energy measurements between 10 and 100 keV. The advantages over the scintillation counter, more commonly used, is the improved resolution of the HgI2 detector and its smaller size. The analyser is primarily used for the detection of low levels of heavy metals on particulate filters. The detectors have also been used on an experimental basis for gamma ray backscatter measurements in the medical field.

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BEDT-TTF-Salze mit quadratischen Platinaten(II) als Gegenionen: [BEDT-TTF]4[Pt(CN)4] / BEDT-TTF-Salts with Square Platinates(II) as Counter Ions: [BEDT-TTF]4[Pt(CN)4]

Zeitschrift für Naturforschung B ◽

10.1515/znb-1990-0607 ◽

1990 ◽

Vol 45 (6) ◽

pp. 763-774 ◽

Cited By ~ 6

Author(s):

Stephan Gärtner ◽

Ilsabe Heinen ◽

Heimo J. Keller ◽

Roland Niebl ◽

Bernhard Nuber ◽

...

Keyword(s):

Structure Elucidation ◽

Room Temperature ◽

Specific Resistance ◽

Structural Phase ◽

Antiferromagnetic Coupling ◽

Neutral Donor ◽

Temperature Conductivity ◽

Room Temperature Conductivity ◽

X Ray ◽

Counter Ions

The compound [BEDT-TTF]4[Pt(CN)4], BEDT-TTF = Bis(4.5-ethylendithiolo)tetrathiafulvalen = C10H8S8, stoichiometry C44H32N4S32Pt, Mr = 1837.9 (g/mol), was obtained by electrocrystallization in at least three different modifications. Two of them could be identified by single crystal X-ray structure elucidation. 1 = β-modification, is isolated in black, lustrous platelets: triclinic, P 1̄, Z = 1, α = 9.7280(30) Å, b = 10.9237(27) Å, c = 16.5432(60) Å, a = 95.820(25)°, β = 98.296(26)°, γ = 115.215(24)°, V = 1547.56 A3, dc = 2.0 (g/cm3), room temperature, Rw = 0.082 for 7322 observed reflections. 2 = y-modification, is isolated in black not very regular crystals: monoclinic, C 2/c, Z = 4, a = 11.163(6) Å, b = 33.56(2) Å, c = 16.56(1) Å, β = 91.39(4)°, V = 6202.04 A3, dc = 1.97 (g/cm3), room temperature, Rw = 0.053 for 1404 observed independent reflections. Both solids contain sheets of BEDT-TTF cations separated by sheets of the counter anions. 1 contains two crystallographically independent BEDT-TTF moieties while 2 contains four independent donor units per cell. Of interest are the very different lengths of the central C=C bonds of the BEDT-TTF moieties which are assumed to reflect the charge density on these ions. In 1 these distances are 1.350(14) Å and 1.306(14) A, respectively, for the two different BEDT-TTF cations in the lattice, in 2 they are 1.372(34) A, 1.401(42) A and 1.289(54) Å respectively. The remarkable differences in these bond lengths indicate, according to published concepts, quite different charges on the different BEDT-TTF units. Two of the distances are shorter than in the neutral donor. Measurements of the specific resistance and the thermopower show that 1 is a metal with a room temperature conductivity of 10 S/cm. At around 200 K 1 becomes semiconducting. 2 turns out to be a semiconductor with a room temperature conductivity of 1—2 S/cm. Around 225 K a structural phase transition occurs. ESR measurements show an antiferromagnetic coupling between the spins in the solid. A third modification (δ) (semiconducting with a room temperature conductivity around 2 × 10-2 S/cm) was identified by ESR investigations.

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Preparation and phase control of nanocrystalline silver indium sulfides via a hydrothermal route

Journal of Materials Research ◽

10.1557/jmr.2001.0469 ◽

2001 ◽

Vol 16 (12) ◽

pp. 3411-3415 ◽

Cited By ~ 30

Author(s):

J. Q. Hu ◽

B. Deng ◽

K. B. Tang ◽

C. R. Wang ◽

Y. T. Qian

Keyword(s):

Room Temperature ◽

Photoelectron Spectra ◽

Hydrothermal Route ◽

X Ray ◽

Transmission Electron ◽

Diffraction Patterns ◽

And Control ◽

Microscopy Images ◽

Room Temperature Raman Spectrum ◽

Weak Peak

A hydrothermal route was proposed to prepare and control nanocrystalline silver indium sulfides (orthorhombic AgInS2, tetragonal AgInS2, and cubic AgIn5S8). The reaction was carried out in an autoclave in the temperature range of 100–280 °C with AgCl, InCl3, and thiourea as reactants. X-ray powder diffraction patterns and transmission electron microscopy images showed that the products were AgInS2 and AgIn5S8 phases and well crystallized with grain diameter in the range of 20–70 nm. X-ray photoelectron spectra of the single AgIn5S8 phase revealed the surface stoichiometry (AgIn5.05S8.11), and its room temperature Raman spectrum showed a strong peak at 130 cm−1 and a weak peak at around 290 cm−1. The influence of reaction temperature on the phases in the final products was investigated. A possible reaction mechanism of the formation of silver indium sulfides was also briefly discussed.

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The Effect of Al on Phase Stability and Oxidation Behavior in Ternary Nb-Ti-Si Alloys

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.310 ◽

2014 ◽

Vol 556-562 ◽

pp. 310-313

Author(s):

Yong Jun Jiang

Keyword(s):

Room Temperature ◽

Oxidation Behavior ◽

Point Of View ◽

Transition Elements ◽

X Ray Diffraction ◽

X Ray ◽

Room Temperature Ductility ◽

Oxidation Properties ◽

Diffraction Patterns ◽

And Control

In this paper, we report a significant improvement in mechanical and oxidation properties of near eutectic Nb–Si alloys by the addition of aluminum (Al) and control of microstructural length scale. Thus in order to develop new alloys, we have to choose proper alloying elements keeping all the above issues in mind. Among the non-transition elements such as Al, Ga, Ge, Sn, and Al is most attractive from the point of view of enhancing the oxidation resistance and room temperature ductility due to substitution of Si with metallic Al . Al forms oxides which are even more thermodynamically stable than Si and Nb based oxides. Al is also soluble in Nb to a greater degree in conjunction with other refractory elementsFig.1 The figure shows composite X-ray diffraction patterns of each sample exposed to air for one hour in a TGA furnace at above mention temperatures.

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Progress in Cd1−xZnxTe (CZT) Radiation Detectors

MRS Proceedings ◽

10.1557/proc-299-249 ◽

1994 ◽

Vol 299 ◽

Cited By ~ 2

Author(s):

J. F. Butler ◽

F. P. Doty ◽

B. Apotovsky ◽

S. J. Friesenhahn ◽

C. Lingren

Keyword(s):

Room Temperature ◽

Ohmic Contacts ◽

Gamma Ray ◽

Surface Effect ◽

Growth Parameters ◽

Radiation Detectors ◽

Imaging Data ◽

Detector Arrays ◽

X Ray ◽

First Time

AbstractResults of a program to improve the performance of Cd1−xZnxTe detectors by adjusting growth parameters to achieve low-strain, high purity low defect crystals, investigating surface effect phenomena and contacting methods, and establishing reproducible manufacturing methods are reviewed and discussed. Processing and fabrication methods were developed which are applicable throughout the composition range. Energy spectra for room temperature Cd1−xZnxTe detectors exhibit resolutions (FWHM) from 2.16 keV at 14 keV to 6.9 keV at 122 keV. An energy resolution of 910 eV at 5.9 keV was achieved at −25 C. Stable ohmic contacts and gamma ray detection for ZnTe are reported for the first time. Applications of Cd1−xZnxTe to nuclear medicine and X-ray fluorescence are discussed. New gamma ray imagers using Cd1-−ZnxTe detector arrays are described, and imaging data for a 32 × 32 monolithic array of 1 mm2 elements on a 42mm × 42mm substrate are presented.

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Pl And Epr Spectroscopy Of Point Defects In Detector-Grade Cd1−xZnxTe

MRS Proceedings ◽

10.1557/proc-487-71 ◽

1997 ◽

Vol 487 ◽

Author(s):

C. I. Rablau ◽

S. D. Setzler ◽

L. E. Halliburton ◽

F. P. Doty ◽

N. C. Giles

Keyword(s):

Point Defects ◽

Room Temperature ◽

Gamma Ray ◽

Paramagnetic Resonance ◽

X Ray ◽

Shallow Donors ◽

Shallow Acceptors ◽

Epr Signal ◽

And Control ◽

Electron Paramagnetic

AbstractCadmium zinc telluride (CdZnTe) is an emerging material for room-temperature x-ray and gamma ray detectors. The identification and control of point defects and charge compensators are currently important issues. Low-temperature photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopies have been used to characterize point defects in CdZnTe crystals grown by the high-pressure Bridgman technique. Luminescence due to shallow donors, shallow acceptors, and deeper acceptors was monitored for a series of samples. An isotropic EPR signal attributed to shallow hydrogenic donors is observed in all samples, and the concentration of shallow donors has been determined. The nature of the defect centers (impurities, vacancies, vacancy-impurity complexes), and the correlation between defect concentration and device performance is discussed.

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XAS spectroelectrochemistry: reliable measurement of X-ray absorption spectra from redox manipulated solutions at room temperature

Journal of Synchrotron Radiation ◽

10.1107/s1600577516005464 ◽

2016 ◽

Vol 23 (3) ◽

pp. 743-750 ◽

Cited By ~ 7

Author(s):

Stephen P. Best ◽

Aviva Levina ◽

Chris Glover ◽

Bernt Johannessen ◽

Peter Kappen ◽

...

Keyword(s):

Room Temperature ◽

Vitreous Carbon ◽

Current Response ◽

Void Space ◽

X Ray ◽

Working Electrode ◽

The Stability ◽

And Control ◽

X Ray Absorption ◽

Reduced Forms

The design and operation of a low-volume spectroelectrochemical cell for X-ray absorption spectroscopy (XAS) of solutions at room temperature is described. Fluorescence XAS measurements are obtained from samples contained in the void space of a 50 µL reticulated vitreous carbon (sponge) working electrode. Both rapid electrosynthesis and control of the effects of photoreduction are achieved by control over the flow properties of the solution through the working electrode, where a good balance between the rate of consumption of sample and the minimization of decomposition was obtained by pulsing the flow of the solution by 1–2 µL with duty cycle of ∼3 s while maintaining a small net flow rate (26–100 µL h−1). The performance of the cell in terms of control of the redox state of the sample and minimization of the effects of photoreduction was demonstrated by XAS measurements of aqueous solutions of the photosensitive FeIIIspecies, [Fe(C2O4)3]3−, together with that of the electrogenerated [Fe(C2O4)3]4−product. The current response from the cell during the collection of XAS spectra provides an independent measure of the stability of the sample of the measurement. The suitability of the approach for the study of small volumes of mMconcentrations of protein samples was demonstrated by the measurement of the oxidized and electrochemically reduced forms of cytochromec.

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Performance of P-I-N CdZnTe Radiation Detectors and Their Unique Advantages

MRS Proceedings ◽

10.1557/proc-487-245 ◽

1997 ◽

Vol 487 ◽

Author(s):

R. Sudharsanan ◽

C. C. Stenstrom ◽

P. Bennett ◽

G. D. Vakerlis

Keyword(s):

Leakage Current ◽

Radiation Detectors ◽

Leakage Currents ◽

Bulk Resistivity ◽

X Ray ◽

Fluorescence Studies ◽

Energy Applications ◽

Low Leakage ◽

Vertical Bridgman ◽

Cdznte Detectors

AbstractWe present the performance characteristics of CdZnTe radiation detectors with a new P-I-N design and their unique advantages over metal-semiconductor-metal (M-S-M) devices. In M-S-M CdZnTe detectors the bulk resistivity of the substrate largely determines the leakage current. High leakage current is a dominant noise factor for CdZnTe detector arrays, coplanar detectors, and detectors used for low X-ray energy applications. P-I-N devices provide low leakage currents. Early CdZnTe detectors exhibited polarization, were limited to small detection volumes, and some required high deposition temperatures. We have developed a new heterojunction design which can be deposited at low temperatures so that even high-pressure Bridgman CdZnTe can be used. Using the P-I-N design, CdZnTe detectors with high detection volumes (>200 mm3) were fabricated and exhibited low leakage current, good energy resolution, and no polarization. These detectors have significant advantages over M-S-M detectors in three specific areas. First, X-ray fluorescence studies require detectors with low leakage currents to provide less spectral broadening due to electronic noise. Second, less expensive vertical Bridgman CdZnTe material can be used for imaging applications since it normally possesses too low of a bulk resistivity to be useful as a M-S-M detector. Third, leakage currents across the anode grid in large volume coplanar detectors can be significantly reduced

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Improved CdZnTe detectors grown by vertical Bridgman Process

MRS Proceedings ◽

10.1557/proc-487-229 ◽

1997 ◽

Vol 487 ◽

Cited By ~ 6

Author(s):

K. G. Lynn ◽

M. Weber ◽

H. L. Glass ◽

J. P. Flint ◽

Cs. Szeles

Keyword(s):

Room Temperature ◽

High Resistivity ◽

Detector Response ◽

Processing Conditions ◽

Bridgman Technique ◽

X Ray ◽

Zn Content ◽

Vertical Bridgman ◽

Γ Ray ◽

Cdznte Detectors

AbstractThe γ ray (57Co) and α particle (241Am) detector response of Cdl-xZnxTe crystals grown by vertical Bridgman technique was studied under both positive and negative bias conditions. Postgrowth processing was utilized to produce a high-resistivity material with improved chargecollection properties. Samples of various Zn concentrations were investigated by I-V measurements and thermally stimulated spectroscopies to determine the ionization energies of deep levels in the band gap. When the post-processing conditions were optimized the lowenergy tailing of the γ-ray photopeaks was significantly reduced and an energy resolution of under 5% was achieved for the 122 keV γ-photon line in crystals with x=0.2 Zn content at room temperature. A peak to background ratio of 14:1 for the 122 keV photopeak from 57Co was observed on the best sample, using a standard planar detection geometry. The low-energy 14.4 keV X-ray line could also be observed and distinguished from the noise.

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