Structural and sub-structural features of chemically deposited Zinc-oxide thin films

We investigated the structural and sub-structural characteristics of ZnO films obtained by chemical bath deposition from solutions of zinc sulfate, thiourea, and ammonia. The duration of deposition ranged from 20- to 120-minutes. The concentration of thiourea was varied from 0.1- to 3-mol. We detailed the structural and sub-structural characteristics of these films using high-resolution scanning electron microscopy and x-ray diffraction. This research enables us to study features of the films’ structural formation, and to determine their basic characteristics, viz., phase analysis, texture quality, lattice constants, grain size, and size of the coherent scattering domain. Regimes were identified for depositing films with optimal structural characteristics for eventual use in solar-energy applications. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3340

Вплив іонізуючого випромінювання на структуру, електрофізичні і оптичні характеристики кристалів Cd1-хZnхTe

Based on X-ray studies, conditions for growth of high structural perfect Cd1-хZnxTe (0,02≤х≤0,1) crystalshave been optimized. In crystals obtained, changes in the structure, electrical parameters and optical transmissionat samples irradiation by g-, b- radiations were investigated. At 60Со source gamma-quanta irradiation with a dose of Ф≥ 105 Gy, a slight decrease of samples’ structure and optical transmission, an increase of holes concentration p and a decrease of charge carrier mobility m in p-type crystals was observed. Within 30-40 days, the values of p and m were relaxed to an initial ones. Changes in structural perfection, optical transmission and electricalparameters of samples irradiated by electrons were more significant.На основі рентгенівських досліджень були оптимізовані умови вирощування кристалів Cd1-хZnxTe (0,02 ≤ х ≤ 0,1) високої структурної досконалості. В одержаних кристалах досліджені зміни структури, електричних параметрів і оптичного пропускання при опромінені зразків g-, b- випромінюванням. При опромінені g-квантами джерела 60Со дозою Ф ≥ 105 Гр спостерігалося незначне погіршення структури і оптичного пропускання зразків, збільшення концентрації дірок р і зменшення рухливості носіїв заряду m в кристалах р-типу. Протягом 30 - 40 діб значення р і m релаксували до вихідних значень. Зміни структурної досконалості, оптичного пропускання і електричних параметрів зразків, опромінених електронами, були більш суттєвими

Variation of electric shielding on virtual Frisch-grid detectors

Because of the low mobility of holes, CdZnTe (CZT) detectors operate as electron-transport-only type devices whose particular geometrical parameters and contacts configurations are specially chosen to minimize the contribution of uncollected holes into the output signal amplitudes (induction effect). Several detector configurations have been proposed to address this problem. One of them employs a large geometrical aspect ratio, parallelepiped-shaped crystal with two planar contacts on the top and bottom surfaces (anode and cathode) and an additional shielding electrode placed on a crystal\u27s side to create the virtual Frisch-grid effect. We studied the effect of the shielding electrode length, as well as its location, on the responses of 6 x 6 x 15 mm(3) virtual Frisch-grid detectors. We found that the length of the shielding electrode placed next to the anode can be reduced to 5 mm with no adverse effects on the device performance. Meanwhile, this allows for charge loss correction by reading the cathode signal

An effect of the networks of the subgrain boundaries on spectral responses of thick CdZnTe detectors

CdZnTe (CZT) crystals used for nuclear-radiation detectors often contain high concentrations of subgrain boundaries and networks of poligonized dislocations that can significantly degrade the performance of semiconductor devices. These defects exist in all commercial CZT materials, regardless of their growth techniques and their vendor. We describe our new results from examining such detectors using IR transmission microscopy and white X-ray beam diffraction topography. We emphasize the roles on the devices performances of networks of subgrain boundaries with low dislocation densities, such as poligonized dislocations and mosaic structures. Specifically, we evaluated their effects on the gamma-ray responses of thick, >10 mm, CZT detectors. Our findings set the lower limit on the energy resolution of CZT detectors containing dense networks of subgrain boundaries, and walls of dislocations

ОПТИМІЗАЦІЯ КЛІНІЧНИХ ДОСЛІДЖЕНЬ ПРИ МУКОЗО-ПЕРІОСТАЛЬНІЙ ТРАВМІ

The actual problem of modern osteology as diagnosis of bone architectonics in the area of bone periosteum is presented in the article. On the base of clinical studies the architectonics features of bone structures after injury were revealed. The efficiency of the proposed technique by applying the Cd(Zn)Te single crystal as a filter for radiovisiography was established. The combination of radiovisiographic research and clinical observation as a single diagnostic process in dentistry was presented.В статье рассмотрена актуальная проблема современной остеологии: диагностика архитектоники костной ткани в области надкостницы. За результатами клинических исследований выявлены особенности архитектоники костных структур после травмы. Установлена эффективность ис-пользования предложенной методики на основе применения монокристалла Сd(Zn)Те как фильтра для радиовизиографичних исследований. Пред-ставлены особенности сочетание радиовизиографичного исследования и клинического наблюдения как единого диагностического процесса в стоматологии.У статті розглянута актуальна проблема сучасної остеології: діагностика архітектоніки кісткової тканини в ділянці окістя. За результатами клінічних досліджень виявлено особливості архітектоніки кісткових структур після травми. Встановлено ефективність використання запропонованої методики на основі застосування монокристалу Сd(Zn)Те як фільтра для радіовізіо-графічних досліджень. Представлено особливості поєднання радіовізіо-графічного дослідження і клінічного спостереження як єдиного діагности-чного процесу в стоматології

Structural and substructural features of chemically deposited zinc oxide thin films

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Thermographic analyses of the growth of Cd1-xZnxTe single crystals

Bulk Cd1-xZnxTe (0<x<0.1) single crystals for gamma-ray detectors are grown mainly from near-stoichiometric melts. We discuss the influence of the thermal pre-history of the melts (superheating, thermo-cycling, and cooling rate) on various physical properties based on our thermographic analyses, electrical conductivity and viscosity measurements. Increasing the Zn content causes non-monotonic dependencies in the quality of the crystals structure

Structural- and optical-properties of CdTe and CdMnTe films

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Electrical Instability of CdTe:Si Crystals

Results of Hall effect measurements of cadmium telluride crystals, doped by silicon (dopant concentration in the melt was 1018 - 1019 cm-3), allowed to classify the studied samples and the conditions under which probably the definite crystal and impurity states are realized. We have found the distinction between 3 type of CdTe:Si crystals: (1) low-resistance p-type crystals with shallow acceptors, in which Si impurity is localized mainly in the large inclusions; (2) semi-insulating crystal with deep acceptors and submicron size dopant precipitates that are source/drain for interstitials Sii - shallow donors; and (3) low-resistance crystals in which the n-type conductivity is provided by shallow donors: Sii (and/or SiCd). Therefore the silicon is responsible for n-type conductivity of doped samples, introducing as a donor Siі and provides semi-insulating state by forming deep acceptor complexes (SiCd-VCd2-)- with (Еv + 0.65 eV). Besides, the submicron silica precipitates, that have a tend to "dissolution" at relatively low temperatures, can act as electrically active centers. Keywords: cadmium telluride, silicon, doping, electrical properties, impurity, precipitates.</span