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It is established that, in PbTe single-crystal samples annealed at 473 and 673 K, there are no acceptor levels with an activation energy of ∼0.1 eV, which are observed in unannealed samples. It is concluded that the above levels in the unannealed sample are connected with defects caused by macrostresses and a nonuniform atom distribution of extrastoichiometric tellurium along an ingot, which arise when growing PbTl crystals and are healed during annealing. [ABSTRACT FROM AUTHOR]

Ga xIn1 − xSb solid solution single crystals ( x = 0.03–0.09) have been grown. The dislocation density and electrophysical parameters are measured. A technique for the growth Ga xIn1 − xSb single crystals by the Czochralski method with GaSb polycrystal feed is developed. The conditions for the growth Ga0.08In0.92Sb single crystals with a more homogeneous distribution of Ga along the bulk are determined. [ABSTRACT FROM AUTHOR]

The photo-electromotive force induced by a speckle pattern vibrating with large amplitude in photorefractive CdTe:V and CdTe:Ge is experimentally studied. This technique is shown to be suitable for transversal amplitude vibration measurement as well as for material response time and associated conductivity characterization. Experiments were carried out with 532 and 1064 nm wavelength illumination over a wide vibration frequency range. The results are in good agreement with a previously reported theoretical model. The studied doped crystals exhibit peculiar different features that are described and discussed. [ABSTRACT FROM AUTHOR]

The growth striation of impurity segregation and electrical properties of Ga0.03In0.97Sb single crystals grown by the Czochralski method in an ultrasonic field have been investigated. It is established that ultrasonic irradiation of the melt during growth significantly decreases the growth striation (in particular, it eliminates striations spaced at a distance of more than 14 μm). The Ga0.03In0.97Sb single crystals grown in an ultrasonic field had a higher charge-carrier mobility and thermoelectric power in comparison with the single crystals grown without ultrasound. [ABSTRACT FROM AUTHOR]

We report the magnetic and magnetotransport properties of Ga1− x Mn x Sb crystals grown with different Mn doping concentrations ( x=0.01, 0.02, 0.03 and 0.04) by the horizontal Bridgman technique. A systematic reduction in lattice parameter with increase in Mn concentration is observed through X-ray diffraction studies. The crystals show negative magnetoresistance and anomalous Hall effect below 10 K. Anomalous Hall coefficient is negative and decreases with increasing Mn concentration. Temperature dependence on magnetization measurement shows a magnetic ordering below 10 K which could arise from GaMnSb alloy formation. Also, ferromagnetism is observed till room temperature due to the presence of MnSb clusters. Existence of MnSb clusters is verified through scanning electron microscopy. The carrier concentration increases with Mn doping and this results in decrease of resistivity. The observed magnetic and transport properties indicate the presence of ferromagnetic phase below 10 K in the studied system. [ABSTRACT FROM AUTHOR]

n-Hg3In2Te6 single crystals with resistivity of 1–2 Ω cm used in photodiodes for the wavelength 1.55 μm are studied. It is shown that electrical conductivity of the material is controlled by donors of two types with ionization energies of 0.063 and 0.18 eV, while the mobility of charge carriers is predominantly controlled by scattering at charged centers. On the basis of the electroneutrality equation, a quantitative description of the observed temperature dependence of the electron concentration in the temperature range from 100 to 370 K is obtained. [ABSTRACT FROM AUTHOR]

Abstract: The mobility of undoped CdZnTe (CZT) crystals grown by vertical Bridgman method is improved by growing crystals without wall contact. Among the different factors playing an important role for appearance of detached growth, we have chosen the freezing rate as an effective factor for investigation with other factors were held constant. After growing a set of samples we have measured the dislocation densities for the grown samples by Warren–Averbach method. Unique results were obtained when we compared the dislocation densities and mobility, together with the freezing rate. This work and the included relations are published for the first time. [Copyright &y& Elsevier]

Abstract: In this work, the requirements of detector-grade semiconductor materials for radiation detectors, applicable in X-ray digital radiology, are identified. The study includes 12 various bulk semi-insulating (SI) GaAs single crystals grown by LEC and VGF methods, undoped and Cr-doped, obtained from 8 different suppliers. Conductivity, Hall, glow discharge mass spectrometry (GDMS), etch pit density (EPD), scanning electron beam induced current (S-EBIC), X-ray and laser scattering tomography (LST) techniques are used for the bulk SI GaAs material evaluation. The radiation detectors fabricated on these SI GaAs single crystals have been characterized by capacitance methods and their performances have been evaluated from detected pulse height spectra of 57Co. The correlation between the physical characteristics of the base materials and the performance of the detectors is demonstrated and discussed. Key detector-grade SI GaAs parameters, useful for material evaluation, are identified. [Copyright &y& Elsevier]

Abstract: After Cd0.8Zn0.2Te (CZT) crystals were prepared by a special design based on Bridgman technique, the transport properties were investigated. The dependence of electrical conductivity, Hall effect, Hall mobility, charge carriers concentration and thermoelectric power on temperatures was carried out in the temperature range (228–500K). The relaxation time for both majority and minority carriers was estimated. The scattering mechanism for carrier transport was discussed in the same temperature range. [Copyright &y& Elsevier]

Abstract: We report the magnetic and transport properties of Ga1−x Mn x P synthesized via ion implantation followed by pulsed laser melting over a range of , namely 0.018–0.042. Like Ga1−x Mn x As, Ga1−x Mn x P displays a monotonic increase of the ferromagnetic Curie temperature with associated with the hole-mediated ferromagnetic phase while thermal annealing above 300 ∘C leads to a quenching of ferromagnetism that is accompanied by a reduction of the substitutional fraction of Mn. However, contrary to observations in Ga1−x Mn x As, Ga1−x Mn x P is non-metallic over the entire composition range. At the lower temperatures over which the films are ferromagnetic, hole transport occurs via hopping conduction in a Mn-derived band; at higher temperatures it arises from holes in the valence band which are thermally excited across an energy gap that shrinks with . [Copyright &y& Elsevier]

The impurity-defect system in the Cd1 − x ZnxTe crystals (0.02 ≤ x ≤ 0.15) is analyzed prior to and after heat treatment at 720–1170 K. It is found that the conductivity in most of these crystals is governed by two types of acceptors, A 1 ( E V = 0.03–0.05 eV) and A 2 ( E V = 0.12–0.15 eV). The variation in electrical properties of the crystals after heat treatment depends on the concentration of background impurities in the starting material and the degree of compensation of acceptor A 1. An increase in the resistivity and homogeneity of the samples is observed after two sequential heat treatments. [ABSTRACT FROM AUTHOR]

Abstract: The structural characteristics of InP single crystals have been investigated depending on the radiation effects produced by fast neutrons and the full spectrum of the reactor neutrons and subsequent heat treatment procedures. The lattice parameter of InP single crystals decreases under neutron irradiation as opposed to other III–V semiconductor compounds. Fast neutrons make the main contribution to the change of the lattice parameter. A thermal neutron component initiates the formation of Sn atoms in the material, but does not influence the change of the lattice parameter significantly. Heat treatment of the irradiated samples up to 600°C causes annealing of the radiation defects and recovery of the lattice parameter. With increasing neutron fluences, the lattice parameter becomes even higher than before irradiation. The data analysis proves the following assumption: anti-site defects PIn mainly contribute to the lattice parameter decrease during neutron irradiation of InP. In this case, anti-site imperfections produce an effect similar to that of vacancy defects. [Copyright &y& Elsevier]

Abstract: InP high electron mobility transistor (HEMT) structures with In0.53Ga0.47As channels and In0.52Al0.48As barriers were grown by molecular beam epitaxy. A GaTe source was used as an n-type dopant. Conventional structures with 50–100Å InAlAs(Te) layers and Te-delta-doped structures were investigated. Both types of structures exhibited good transport characteristics, with mobilities of 8000–10,000cm2/V-s and sheet densities of 1–4×1012/cm2. Fluorination studies showed similar behavior for Si- and Te-doped HEMT structures, with donor deactivation resulting in substantial reductions in mobility and carrier density after exposure to fluorine. [Copyright &y& Elsevier]

We report effect of external ac-field on photorefractive properties of CdTe:Ge at 1.06 μm. Phenomena related to excitation of the space-charge waves (SCW) of traps recharging, such as spatial subharmonics generation and resonant two-beam coupling, are studied. Dramatic enhancement of the photorefractive response is achieved in ac-biased crystal by adjustment of recording conditions (field and grating spacing) to eigen resonance related to excitation of the space charge waves. [Copyright &y& Elsevier]

Undoped, S-doped and Fe-doped InP crystals with diameter up to 4-inch have been pulled in 〈1 0 0〉-direction under P-rich condition by a rapid P-injection in situ synthesis liquid encapsulated Czochralski (LEC) method. High speed photoluminescence mapping, etch-pit density (EPD) mapping and scanning electron microscopy have been used to characterize the samples of the single crystal ingots. Dislocations and electrical homogeneity of these samples are investigated and compared. By controlling the thermal field and the solid–liquid interface shape, 4-inch low-EPD InP single crystals have been successfully grown by the rapid P-injection synthesis LEC method. The EPD across the wafer of the ingots is less than 5×104 cm−2. Cluster defects with a pore center are observed in the P-rich LEC grown InP ingots. These defects are distributed irregularly on a wafer and are surrounded by a high concentration of dislocations. The uniformity of the PL intensity across the wafer is influenced by these defects. [Copyright &y& Elsevier]

High-purity semi-insulating CdTe crystals have been successfully grown by encapsulated (B2O3) Bridgman technique. The procedure strongly limits component losses allowing the achievement of stoichiometry control material and keeps a low level of impurity contamination as shown by mass spectroscopy analysis data. When strictly stoichiometry-controlled and high-purity polycrystalline source material has been used, high-resistivity crystals have been obtained without any intentional doping. EPD values in the range of 1–3×104 cm−2 have been observed in a wide region of the crystals. Luminescence spectroscopy confirms the purity and good structural quality of the material. The proposed method avoids the technical problems posed by the High Pressure Bridgman technique and fits the requirements for CdTe/CdZnTe crystals large-scale production. [Copyright &y& Elsevier]

Growth of (Cd1−xZnx)1+yTe(CZT) single crystals is tried by a modified Bridgman method using a reservoir chamber containing Cd and Zn metals with a fixed mole ratio. The aim of this method is to obtain the single crystals with controlled deviation y from stoichiometry and homogeneous target composition x. A suitable growth condition was examined experimentally and the effectiveness of this method for controlling the deviation y from stoichiometry and the composition x is confirmed. [Copyright &y& Elsevier]

Recently, ZnO attracts a wide interest as a promising material for the application in optoelectronic devices working in the blue and ultraviolet region and (when doped with magnetic impurities) in spintronic devices. Unfortunately, the technology of good, large (e.g.: 2.5–5 cm in diameter) single crystals is very difficult, even as compared with other II–VI compounds. We report on the successful growth of the ZnO crystals with a chemical vapour transport (CVT) method and on the characterisation of them. The source material is synthesised at 650 °C from oxygen and zinc vapours and subsequently, baked (as a powder) to achieve stoichiometry. The crystals grow (with the rate 1–2 mm per day) in the graphite-covered quartz ampoules containing pure (6N) hydrogen or nitrogen and a small amount of water vapour. The crystals, both as-grown and annealed in pure oxygen, are characterised by the measurements of photoluminescence spectra, transmission spectra, far infrared transmission, X-ray diffraction and electrical transport. The surface region is analysed by the secondary ion mass spectroscopy (SIMS). [Copyright &y& Elsevier]