Properties of CdTe(Cl) crystal used for radiation detector

Shoji, Tadayoshi; Ohba, K.; Onabe, Hideaki; Suehiro, T.; Hiratate, Y.

doi:10.1109/23.256589

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…In a typical measurement cycle the sample was held at a fixed temperature and at an initial P Cd0 until its conductivity (σ 0 ) was stabilized. After that the cadmium source temperature was step-like changed to obtain a sharp change in P Cd and 1 Analogous procedure can also be applied in the case of a donor atom occupying Cd sublattice (X Cd ). The corresponding forms differ from equations ( 18) and (19)…”

Section: Methodsmentioning

confidence: 99%

“…A reliable preparation of x-and gamma-ray CdTe detectors is based on doping by a proper donor element, which compensates native and extrinsic acceptors commonly present in as-grown single crystals. Chlorine substituting Te in the anion sublattice (Cl Te ) is often used for this purpose [1,2]. The research of the defect properties of CdTe:Cl is thus needed to understand the defect structure [3] and to optimize the performance of the detectors.…”

Section: Introductionmentioning

confidence: 99%

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Chemical diffusion in CdTe:Cl

Grill

Nahlovskyy

Belas

et al. 2010

Semicond. Sci. Technol.

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High-temperature in situ galvanomagnetic measurements are reported in chlorine-doped CdTe, [Cl] ≈ 4 × 10 18 cm −3 at temperatures T = 600-700 • C near Cd saturation. The chemical diffusion coefficient D is determined by means of relaxation of electrical conductivity after a step-like change of ambient Cd pressure (P Cd ) and approximated well by a trial function D (cm 2 s −1 ) = 1.5 × 10 7 exp(−2.55 eV/k b T )/ √ P Cd (atm). Both D and equilibrium conductivity are calculated on the basis of a defect model in which donors Cl Te are compensated by divalent acceptors Cd vacancies (V Cd ) and monovalent acceptor complexes (Cl Te V Cd ). The properties of native point defects are consistent with undoped CdTe. It is shown that D can be fit well assuming different diffusion coefficients for singly and doubly charged V Cd .

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical diffusion in CdTe:Cl

Grill

Nahlovskyy

Belas

et al. 2010

Semicond. Sci. Technol.

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“…[1][2][3][4] However, CdTe detectors are limited to small sizes, which makes the instruments less sensitive to gamma-emitting sources. In addition, the leakage currents are too large for many X-ray applications.…”

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confidence: 99%

“…Cd 1Ϫx Zn x Te (CZT) and cadmium telluride (CdTe) have great potential for application in high-energy X-ray and ␥-ray detectors. [1][2][3][4] However, CdTe detectors are limited to small sizes, which makes the instruments less sensitive to gamma-emitting sources. In addition, the leakage currents are too large for many X-ray applications.…”

mentioning

confidence: 99%

Epitaxial Growth and Nitrogen Radical Doping of CdZnTe

Noda

Aoki

Nakanishi

et al. 1999

J. Electrochem. Soc.

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Cd 1Ϫx Zn x Te (CZT) and cadmium telluride (CdTe) have great potential for application in high-energy X-ray and ␥-ray detectors. [1][2][3][4] However, CdTe detectors are limited to small sizes, which makes the instruments less sensitive to gamma-emitting sources. In addition, the leakage currents are too large for many X-ray applications. Although CdTe is very promising as a gamma-ray detector due to its high absorption coefficient, there are some drawbacks that limit its widespread use in these devices. It has been suggested that alloying CdTe with certain other materials to produce ternary compounds with higher bandgaps and increased energy of defect formation would lead to solid-state detectors with improved performance. 5 Cd 1Ϫx Zn x Te films with Zn composition x between 0.2 and 0.8 exhibit poor crystallinity as observed by X-ray diffraction (XRD). This effect has been attributed to phase separation resulting from the existence of a miscibility gap in the CdTe-ZnTe phase diagram. 6 Therefore, by CZT crystal growth, the content of Zn is limited to less than 10%. 7 High-quality crystals of CZT with high concentrations of Zn are difficult to achieve by the usual methods of crystal growth.We have studied a low-pressure, low-substrate-temperature metallorganic chemical vapor deposition (MOCVD) method using hydrogen radical reaction. 8,9 In this method, hydrogen radicals are introduced in the reaction region of the chemical vapor deposition (CVD) chamber in order to cause dissociation of the organic material. As alloy growth at high temperature is considered to contribute to phase separation, it is important to use a low substrate temperature. When nitrogen is introduced into the hydrogen plasma source, p-type CdZnTe films are expected as a result of nitrogen radical doping. 10 In this paper we report CdZnTe crystal growth and p-type doping characterization.Experimental Epitaxial CdZnTe films were prepared using the remote plasmaenhanced (RPE) MOCVD apparatus illustrated in Fig. 1. The apparatus was equipped with a load-lock system to avoid exposure of the reactor to air, together with a vacuum system with a turbomolecular pump. The substrates on the substrate holder were contained in a vertical type stainless steel reactor and were mounted on a resistive heater. Dimethylcadmium (DMCd) and diethylzinc (DEZn) were used as the group II source monomers, and diethyltellurium (DETe) was used as the group VI source monomer. These materials were introduced into the reactor from a bubbling cylinder kept at constant temperature and pressure. The flow rates of the gases were controlled by a mass-flow controller. Gases were introduced into the reaction region above the substrates. Hydrogen (H) radicals, generated using a radio frequency (rf, 13.56 MHz) coil mounted 30 cm away from the substrate, were introduced into the reaction chamber with the source materials. Semi-insulating GaAs(100) wafers were used as substrates. Prior to the growth process, the substrates were chemically etched in a liquid acid mixture of H 2 SO 4 , ...

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“…Compound semiconductors such as CdTe [1], PbI 2 [2], TlBr [3] have been investigated as materials for room temperature radiation detectors. Fabrication of room temperature radiation detectors requires materials that have some physical properties such as high atomic number, high density and wide bandgap energy.…”

Section: Introductionmentioning

confidence: 99%

Bismuth iodide (III) crystals for nuclear radiation detectors

Matsumoto

Hitomi

Shoji

et al.

2001 IEEE Nuclear Science Symposium Conference Record (Cat. No.01CH37310)

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Bismuth tri-iodide (BiI 3 ) is an attractive material for room temperature radiation detectors because of its wide bandgap energy and high photon stopping power. In this study, BiI 3 crystals have been grown by the vertical Bridgman technique using commercially available powder. The grown crystals have been characterized in terms of their structural properties and stoichiometry. Room temperature radiation detectors have been fabricated from the crystals and tested by measuring their leakage currents and spectroscopic responses. A clear peak corresponding to 5.48 MeV -particles ( 241 Am) was recorded with a BiI 3 detector 82 µm thick with 0.8 mm 2 palladium electrodes. The energy resolution of the 5.48 MeV peak was measured to be 2.2 MeV FWHM. 2344 0-7803-7324-3/02/$17.00 © 2002 IEEE

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Properties of CdTe(Cl) crystal used for radiation detector

Cited by 10 publications

References 6 publications

Chemical diffusion in CdTe:Cl

Chemical diffusion in CdTe:Cl

Epitaxial Growth and Nitrogen Radical Doping of CdZnTe

Bismuth iodide (III) crystals for nuclear radiation detectors

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