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A Cd1−xMgxTe crystal is considered an ideal room temperature radiation detector material due to its excellent opto-electrical properties. In this paper, three large Cd0.95Mg0.05Te ingots with a diameter of 30 mm and a length of more than 100 mm were successfully grown by the modified vertical Bridgman method under different excess Te conditions (0.5 at%, 1.0 at% and 1.5 at%). The results showed that the as-grown Cd1−xMgxTe crystals have cubic zinc-blende structures. The band gap of the crystals ranged from 1.43 eV to 1.52 eV, the density of Te inclusions ranged from 2.7 × 103 cm−2 to 1.0 × 105 cm−2, the resistivity ranged from 8.22 × 106 Ω cm to 1.51 × 1010 Ω cm, and the IR transmittance ranged from 33% to 60%. With the increase of excess Te, the band gap, crystal resistivity and infrared (IR) transmittance decreased, and the density of Te inclusions increased. The analysis of the low temperature photoluminescence (PL) and Raman scattering spectra indicated that the crystal quality deteriorated gradually with the increase of excess Te. The crystal grown under 0.5 at% excess Te conditions had the best optical and electrical properties. [ABSTRACT FROM AUTHOR]

Cadmium magnesium telluride (CdMgTe) is a very perspective material for room temperature radiation detectors. In this paper, two large-size Cd 0.95 Mg 0.05 Te ingots doped with different In amounts were grown by vertical Bridgman method under Cd-compensated condition. It was found that the impurities were distributed inhomogeneously and In dopant mainly concentrated in the tail of two ingots. Compared with the ingot grown by doping with 5 ppm In, the ingot grown by doping with 10 ppm In had more uniform distribution of Mg element, higher IR transmittance, less Te inclusions and better crystal quality. FIB-TEM and HRTEM analysis showed that the size of Te precipitates was less than 10 nm, the composition of both crystals was rich in Cd and was single crystal with sphalerite structure. The type of dislocation was edge dislocation and the density was high. In addition, the maximum IR transmittance and highest resistivity were 64 % and 1.53 × 1010 Ω cm, respectively. The planar detector prepared with 10 ppm In doped crystal had an energy resolution of 19.6 % and a (μτ) e value of 1.38 × 10−3 cm2/V, which could meet the requirements for high performance room-temperature radiation detector. • CdMgTe is a very perspective material for room temperature radiation detectors. • Large-size Cd 0.95 Mg 0.05 Te ingots are successfully grown by the modified vertical Bridgman method. • Cd compensation and different In content conditions are used together to improve crystal resistivity. • The as-grown crystal with high resistivity can be used for detector. [ABSTRACT FROM AUTHOR]

CdMgTe crystal is a hopeful room temperature radiation detection material because of some potential advantages. The Cd0.95Mg0.05Te ingot with free of inclusion was successfully grown by a modified Bridgman method in this paper. This results was achieved by using a significant excess cadmium and in situ annealing during the growth process. The grown ingot was about 30 mm in diameter and 120 mm in length. The CdMgTe crystal had a cubic zinc-blende structure. The distribution of Mg element along growth direction was homogeneous. In the whole ingot, no inclusions were observed in IR images and as high IR transmittance as above 60% was measured. Raman scattering spectroscopy showed a good crystal quality for CdMgTe crystals. Moreover, the resistivity with 109 Ω cm order of magnitudes for the ingot could be useful for the fabrication of room temperature radiation detector. [ABSTRACT FROM AUTHOR]

Cadmium manganese telluride is a promising material for fabricating room-temperature nuclear radiation detectors widely used in medical imaging, environmental protection, nuclear security detection, astrophysics, and so on. The Cd0.9Mn0.1Te: V (V: CMT) crystal examined in this work was grown through the Te solution (10% excess) vertical Bridgman method. The low-temperature photoluminescence (PL) spectra indicated that the grown crystal has good quality. A simultaneous thermal excitation current spectrum was used to characterize the effect of vanadium doping on the level defects in the crystal. The current–voltage and Hall test results showed that the crystal resistivity was (3.781–6.185) × 1010 Ω cm. The conductivity was of n type. The carrier concentration was (1.69–9.94) × 106 cm−3. The Hall mobility was (3.08–9.29) × 103 cm−2 V−1 s−1. The maximum measured ratio of the light and dark currents, when the crystal was exposed to 5 mW white light, was 11. In addition, the room-temperature electron mobility-lifetime product of the middle sample was 6.925 × 10−4 cm2 V−1 using the 241Am@5.48 MeV α particle source. [ABSTRACT FROM AUTHOR]

• High-resistivity CMT:In single crystals were annealed under H 2 atmosphere. • Optical properties of CMT:In crystals were obviously effected by hydrogenation. • Photoluminescence measurements indicated that hydrogen can passivate donors, impurities and dislocation effectively. • The best condition of passivation for H 2 atmosphere annealing is 573 K for 30 h. In order to investigate the passivation effects of hydrogen, high-resistivity indium doped cadmium manganese telluride (CMT:In) single crystals were annealed in H 2 atmosphere. The results indicated the concentration of Mn element and the density of Te inclusions did not change after annealing. Both the resistivity and IR transmittance increased because of the reduction of the carrier concentration. The intensity of (D 0, X) peak and (D 0, h) peak decreases remarkably because of the passivation of the indium donor. The donor–acceptor pair peak (DAP) peak disappeared, which was due to the dissociation of [V Cd − In Cd ] complexes and the passivation of the impurities by hydrogen. Moreover, D complex peak consisted of two peaks. The intensities of D 1 peak increased and D 2 peak decreased because the passivation of hydrogen on the donor and dislocation, respectively. The best condition of passivation for H 2 atmosphere annealing is 573 K for 30 h. [ABSTRACT FROM AUTHOR]

Surface treatment is very important for detector-grade Cd 1−x Zn x Te crystals. In this paper, electrical properties of detector-grade Cd 1−x Zn x Te single crystals passivated by KMnO 4 and K 2 S 2 O 8 solutions were investigated. Four passivation agents, H 2 O 2 , (NH 4) 2 S, KMnO 4 and K 2 S 2 O 8 , were compared. The results indicated that the leakage current decreased obviously after passivation. It was found that KMnO 4 and K 2 S 2 O 8 had better passivation effect. When the passivation time was 1 min and 2 min, KMnO 4 had the best passivation effect, and the leakage current of Cd 1−x Zn x Te crystal was as low as 1.3 nA. However, when the passivation time was 5 min, the passivation effect of K 2 S 2 O 8 was the best, and the leakage current was as low as 0.7 nA. The chemical reactions of KMnO 4 and K 2 S 2 O 8 with Cd 1−x Zn x Te crystals were proposed due to XPS analysis. PL spectra showed that the surface properties of the Cd 1−x Zn x Te crystals changed obviously after passivation. 241Am γ -ray @59.5 keV energy resolution of the detectors fabricated with the crystals passivated by KMnO 4 and K 2 S 2 O 8 solutions for 5 min were notably improved. In particular, the energy resolution of Cd 1−x Zn x Te planar detector with K 2 S 2 O 8 passivation could reach 8.03% and was improved by 236%. • Surface treatment is very important for room temperature detectors. • Electrical properties of passivated detector-grade Cd 1−x Zn x Te single crystals were investigated. • Four passivation agents, H 2 O 2 , (NH 4) 2 S, KMnO 4 and K 2 S 2 O 8 , were compared. • The leakage current decreased obviously after passivation. • Energy resolution of the detectors passivated by KMnO 4 and K 2 S 2 O 8 solutions were notably improved. [ABSTRACT FROM AUTHOR]

In this paper, an effective annealing method in which CdMnTe:In (CMT:In) single crystals were coated with CMT powders of the same composition was used to improve the crystal quality of CMT:In crystals. The results indicated that the density of Te inclusions decreased as the annealing time increased. The resistivity and IR transmittance of annealed CMT:In crystals were enhanced obviously. The resistivity of 120 h annealed crystal increased even two orders of magnitude. The reduction of full-width at-half-maximum (FWHM) and the increase of the intensity of X-ray rocking curve indicated an improvement of the crystal quality. PL measurements also showed the crystal quality improved after annealing. No characteristic peak of 241 Am γ-ray could be observed in the detector fabricated with as-grown crystal. Remarkably, for the detector fabricated with annealed crystals, the peak of 241 Am γ-ray appeared. And the energy resolution and μτ value were improved as the annealing time increased. Specially, 120 h annealed CMT:In crystal with 10.11% energy resolution and 1.20×10 −3 cm 2 /V μτ value has the best detector performance. [ABSTRACT FROM AUTHOR]

In this paper, detector-grade CdMnTe:In (CMT:In) single crystals were annealed under Te atmosphere with various annealing times. The results indicated that the density of Te inclusions had not changed as the annealing time increased, whereas the resistivity exhibited an initial increase followed by a decrease. The conduction type was changed from weak n -type conduction in as-grown crystal to p -type conduction in 60 h annealed crystal. The IR transmittance decreased obviously as the annealing time increased. In the PL spectra, the obvious reduction of the intensity of ( D °, X ) peak and the increase of the intensity of the D complex peak in the annealed CMT:In crystals indicated a degradation of the crystal quality. The energy resolution of the detector fabricated with 15 h annealed crystal was improved, whereas the μτ values of the detectors fabricated with all annealed crystals were reduced. Specially, the characteristic peak of 241 Am γ-ray could not be observed in the detectors fabricated by 60 h annealed crystals. Therefore, optimal annealing temperature and the duration are 773 K and 15 h, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] High-resistivity CZT:In single crystals were annealed by an effective method. [•] Te inclusions in CZT:In crystals were eliminated completely after annealing. [•] Photoluminescence measurements indicated that the crystal quality was improved. [•] D complex peak consisted of Cd vacancy-related and dislocation-related defects. [ABSTRACT FROM AUTHOR]

Abstract: High-resistivity In-doped CdZnTe (CZT:In) single crystals were obtained by annealing under Te atmosphere. Photoluminescence spectrum was used to investigate annealed CZT:In single crystals. The results indicated that (D 0, X) peak which is related to the crystal quality appeared after annealing. The donor–acceptor pair peak DAP mainly originated from the complex consisted of the donor In+ Cd and the acceptor [In+ CdV2− Cd]−. The intensity of DAP peak decreased, which might suggest that the impurities were removed. Moreover, D complex peak containing two peaks for as-grown CZT:In consisted of Cd vacancy-related (D 1) and dislocation-related (D 2) defects. However, the intensity of D 2 peak was very low because of the elimination of Cd inclusions after annealing. And the intensity of D 1 peak increased because of the increase of Cd vacancies by evaporating for a long time. [Copyright &y& Elsevier]

Abstract: In this paper, three typical kinds of Te inclusions were observed in indium-doped CdZnTe (CZT:In) crystals. Characterizations revealed that the size of these Te inclusions was 10–30μm. They are homogeneously distributed in CZT:In crystals without defects such as twin crystal and sub-grain boundary, whereas they are inhomogeneously distributed in CZT crystals without these defects. Moreover, the mechanism of morphology evolution of Te inclusions was proposed according to annealing experiments. Tetrahedron Te inclusions preferentially formed during growth, to which hexagonal Te inclusions transformed. Near-hexagonal Te inclusions were the intermediate shape. All kinds of Te inclusions could be eliminated by post-growth annealing under Cd/Zn atmosphere. [Copyright &y& Elsevier]

In this paper, several interesting kinds of Cd inclusions were observed in indium-doped CdZnTe (CZT:In) crystals. Characterizations revealed that all inclusions were actually clusters of many irregular Cd precipitates with a size lower than 1 μm. The needle-like Cd inclusion only had three orientations (12̅1), (2̅11) and (211) along which dislocations and stacking faults lie. The cross-like Cd inclusion consisted of two crossed needle-like inclusions with a 120° included angle. And the star-like Cd inclusion consisted of three crossed needle-like inclusions with a 120° included angle to each other. The mechanism of morphology evolution of Cd inclusions is proposed for the first time. Moreover, all kinds of Cd inclusions could be completely eliminated by appropriate post-growth annealing under a Te atmosphere. [ABSTRACT FROM AUTHOR]

• CdMnTe and CdMgTe crystals are two promising radiation detector materials. • Crystal quality and detector performance are greatly affected by Te inclusions. • Correlation between Te inclusions and opto-electrical properties are summarized. In this paper, the effects of Te inclusions on the optical and electrical properties of CdMnTe and CdMgTe crystals grown by the modified vertical Bridgman method were investigated. For CdMnTe ingot, the average size and density distribution of Te inclusions along axial direction were in the range of 12 ~ 29 μm and 1.53 × 104 cm−2 ~ 2.81 × 105 cm−2, respectively. For CdMgTe ingot, the average size and density distribution of Te inclusions were in the range of 6 ~ 20 μm and 8.17 × 103 cm−2 ~ 2.42 × 104 cm−2, respectively. The density and size of Te inclusions increased gradually from the first-to-freeze part to the last-to-freeze part for CdMnTe ingot, while that of CdMgTe ingot first decreased and then increased. For both CdMnTe and CdMgTe ingots, the resistivity, IR transmittance and FWHM of (D 0, X) peak first increased and then decreased from the first-to-freeze part to the last-to-freeze part. The middle-to-freeze parts of both ingots had the best crystal quality. For both CdMnTe and CdMgTe detectors, the energy resolution and (μτ) e value were first increased and then decreased from the first-to-freeze part to the last-to-freeze part. The detectors fabricated by the middle-to-freeze parts of both crystals had the best performance and can could meet the requirements of room temperature radiation detection. PACS: 78.30.Fs; 78.55.Et; 81.40.Ef. [ABSTRACT FROM AUTHOR]

[Display omitted] • The solid-liquid interface and component distribution of the crystal were systemically investigated for the first time. • Based on the giant Faraday effect, the optical isolator was fabricated. The growth of large-sized Cd 0.9 Mn 0.1 T: V ingot was performed using the Te solution vertical Bridgman method. The ingot was cut into wafers and marked for scientific evaluation and property analysis. Through infrared microscopic analysis, we observed the planar growth interface for the first time, and the X-ray diffraction analyses indicated that the crystal possessed excellent crystallinity. Electron probe microanalysis revealed the homogeneous distribution of Mn, Cd, and Te not only in axial, but in radial direction. Inductively Coupled Plasma Mass Spectrometer investigated the distribution rules of various impurities in the axial direction. Te inclusions investigations showed the smaller sizes and the lower densities than previous studies, and the Infrared transmittance was almost up to the theoretical value 63%. These tests have confirmed that the grown crystals are perfect and can be used for device fabrication. The giant Faraday rotation of monochromatic polarized light was generated in the band edge because of the great contributions of the interband exciton transitions. Based on the Faraday effect, the 780 nm optical isolator was fabricated. [ABSTRACT FROM AUTHOR]

The fine morphologies of microscale Te inclusions in CdZnTe single crystal were investigated to reveal their shape evolution. Such inclusions from crystal ingots with different post-growth cooling rates were analyzed using scanning electron microscopy after surface treatment. A tetrakaidecahedron model embodying {100} and {111} matrix facets was developed to interpret the form of the Te inclusions. An entire shape evolution process was also proposed where the final configuration of the Te inclusions was a tetrahedron comprising {111}B facets. [ABSTRACT FROM AUTHOR]

• Most of perfect dislocations dissociate into partials in the (Cd, Mn)Te crystal. • The synthesized partials are prone to generate the nipped stair rod. • A Z-shape faulted dipole is locked by two stair rod dislocations. • The dislocations sliding on the (1 ¯ 11) plane pile up to induce the S-shape microcrack. The formation of a faulted dipole shaped like a letter Z (Z-shape) and a microcrack shaped like a letter S (S-shape) was investigated in (Cd, Mn) Te single crystal by transmission electron microscopy. Dislocations around the microcrack were determined as perfect dislocations and Shockley partial dislocations (partials) by different two-beam conditions. The nipped stair rod dislocation was produced by the interaction of two partials lying on mutually inclined {1 1 1} planes. The faulted dipole was generated by two partials moving toward the opposite directions on parallel {1 1 1} planes. Owing to the locking effect of Z-shape faulted dipole, the S-shape microcrack occurred along [1 1 1 ¯ ] direction. [ABSTRACT FROM AUTHOR]