Thermodynamic analysis of processes creating the defects in cadmium telluride crystals under conditions of high-temperature annealing

The defective structure of specifically undoped cadmium telluride crystals was researched using the theory of thermodynamic potentials. The calculated concentration of point defects and free charge carriers in the CdTe crystals, depending on technological factors of two-temperature annealing (annealing temperature T and partial pressure of cadmium PCd vapor). The dominant types of defects that determine the basic properties of the material n- and p-type conduction were determined

Вплив ступеню компенсації на детектуючі властивості кристалів Cd0.9Zn0.1Te, легованих індієм

The electrical characteristics of In-doped Cd0.9Zn0.1Te (CZT:In) crystals with concentration of  Со = 3,5×1017 cm-3, which are used in X- and gamma-radiation detectors, were investigated. CZT:In crystals possess a weakly pronounced n-type conductivity and had a resistivity of (1 ¸ 2)*109 Ohm´cm at 293 K. In/CZT:In/In structures with ohmic contacts and Cr/CZT:In/In structures with Schottky barriers were created on their base. The temperature dependences of the resistivity in investigated material were analyzed and explained. The energy position of the deep level responsible for the material’ dark conductivity was found. Due to the study of the temperature dependencies of currents limited by space-charge and of currents of the ohmic section of the volt-ampere characteristics (I-VC), the compensation degree of CZT:In crystals is determined. It was found that Cr/CZT:In/In structures with a Schottky diode, fabricated on crystals with a lower compensation degree, possessed the best detection properties than similar structures fabricated on crystals with a greater compensation degree.Досліджено електричні характеристики кристалів Cd0.9Zn0.1Te, легованих індієм (CZT:In) з концентрацією Со = 3,5×1017 cm-3, які застосовуються у детекторах X/γ-випромінювання. Кристали CZT:In володіли слабко вираженим n-типом провідності та мали питомий опір (1 ¸ 2)×109 Ом·см при 293 К. На їх основі створено структури з омічними контактами In/CZT:In/In та структури Cr/CZT:In/In з діодом Шотткі. Проаналізовано та пояснено температурні залежності питомого опору в досліджуваному матеріалі. Визначено енергетичне положення глибокого рівня, відповідального за темнову електропровідність матеріалу. На основі досліджень температурних залежностей струмів обмежених просторовим зарядом і струмів омічної ділянки вольт-амперної характеристики, визначено ступінь компенсації кристалів CZT:In. Встановлено, що кращими детектуючими властивостями володіли структури Cr/CZT:In/In з діодом Шотткі, виготовлені на кристалах з меншим ступенем компенсації, ніж аналогічні структури, виготовлені на кристалах з більшим ступенем компенсації.&nbsp

Optical Characteristics and Composition of Cd1 – xMnxTe Films Obtained by the Close Spaced Sublimation Technique

Study of the optical properties of Cd1 – xMnxTe films obtained by the close spaced sublimation technique was carried out. Measuring of the optical characteristics of the layers was performed by the spectrophotometric analysis method near the “red boundary” of the semiconductor photoactivity. This research allowed to obtain the spectrum distributions of the transmission T(λ), reflection R(λ) and absorption α(λ) coefficients of the films as well as estimate the band-gap energy of the compound. The values of the band-gap energy were used for determination of manganese concen-trations in the films depending on the growth conditions. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3024

Effect of Laser Annealing on the Properties of the Surface of Polycrystalline CdZnTe Thick Film

In this work effect of laser annealing on properties of surface of CdxZn1-xTe (CZT) films was studied. CZT layers were deposited by co-evaporation of CdTe and ZnTe using close-spaced vacuum sublimation (CSVS) method. Structural properties and chemical composition of films were studied by X-ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS). The annealing of the sample was carried out with the help of micro-Raman infrared laser of 785 nm wavelength at maximal 100x magnification. It was established that laser annealing of the surface substantially causes redistribution of Zn atoms. More detailed study of the sample by the scanning of surface with the micro-Raman method allows to determine trend in this process and to detect Te-rich zones. Improvement of the crystal quality near annealed area of the thick film was achieved

Effect of Laser Annealing on the Properties of the Surface of Polycrystalline CdZnTe Thick Film

In this work effect of laser annealing on properties of surface of CdxZn1-xTe (CZT) films was studied. CZT layers were deposited by co-evaporation of CdTe and ZnTe using close-spaced vacuum sublimation (CSVS) method. Structural properties and chemical composition of films were studied by X-ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS). The annealing of the sample was carried out with the help of micro-Raman infrared laser of 785 nm wavelength at maximal 100x magnification. It was established that laser annealing of the surface substantially causes redistribution of Zn atoms. More detailed study of the sample by the scanning of surface with the micro-Raman method allows to determine trend in this process and to detect Te-rich zones. Improvement of the crystal quality near annealed area of the thick film was achieved

Structural and optical-properties of CdTe and CdMnTe films

We undertook a detailed investigation of the structural- and optical-properties of CdTe- and Cd1-xMnxTe-semiconductor films deposited by close-spaced vacuum sublimation using thermal evaporation on non-oriented substrates. From our structural- and phase-analysis of the layers, we obtained information on their structure, deformations, grain size, and content of dislocations for films deposited at different substrate temperatures. We considered that despite the presence of defects in the crystals, the films offer promise for fabrication into x-ray detectors. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3013

Methodological Aspects of Educational Process and Medical Navigation Technology in Dentistry Clinic

Резюме. Розглянуто застосування методики П. Пшенічки разом із запатентованим приладом медичної навігації для навчання студентів у стоматологічній практиці. Встановлено ефективність використання інтерактивних методів навчання на основі сучасних інформаційних технологій, зокрема доведено, що таке поєднання дає можливість розвинути клінічні навички початківців та розширює показання до медичної навігації у стоматології. Summary. Application of P. Pshenichka's method together with the medical navigation patented device for training of students in stomatological practice is considered. Efficiency of the use of interactive methods of training on the basis of modern information technologies is established, in particular it is shown that such combination allows to develop clinical skills of beginners and extends indications for the medical navigation in stomatology

Registration of high-intensity electron and x-ray fields with polycrystalline CVD diamond detectors

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Raman analysis of Zn1-xMnxTe polycrystalline films

In this paper, we have investigated some structural properties, Raman spectra of Zn1-xMnxTe films deposited by the closed space vacuum sublimation under different growth conditions. The obtained results of the Raman spectroscopy and XRD analysis show single phase composition of the samples. The presence of phonon replicas in the Raman spectra of the films indicates their high structural quality. The manganese content (about 7 %) in the layers was determined according to shifting the relative peaks positions. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/33848This work performed under the state budget project №0113U000131 Ministry of Education and Science of Ukraine and with the support of the State Agency for Science, Innovation and Informatization of Ukraine

Raman Characterisation of Cd1−xZnx Te Thick Polycrystalline Films Obtained by the Close-Spaced Sublimation

In this work, we studied the Raman spectra of thick polycrystalline Cd1-xZnx Te (CZT) films with x ranged from 0.06 to 0.68. Additionally, the surface morphology and structural properties were studied in order to determine the crystalline quality of the samples. The Raman spectra had a two-mode behavior typical for CZT solid solution and showed CdTe- and ZnTe-like longitudinal and transverse optical modes. The relationship between the frequencies of CdTe- and ZnTe-related modes on x was studied. We observed the deviation of the compositional dependence of phonon mode frequencies for polycrystalline CZT films in comparison with a similar dependence for CZT single crystals. Such deviation was caused by the effect of structural defects in polycrystalline films on frequencies of vibrational modes. The values of excitation wavelength, which allow achieving of high signal-to-noise ratio on the Raman spectra of CZT films with different zinc concentration in the result of resonant enhancement of phonon modes intensities, were experimentally determined