Особенности влияния условий роста на структурные и оптические свойства пленок Zn0.9Cd0.1O

The influence of the magnetron power and the gas ratio Ar/O2 on the microstructure and the optical properties of Zn0.9Cd0.1O films is studied. The films were deposited with the use of the dc magnetron sputtering technique at a temperature of 250 ◦C. Atomic force microscopy (AFM) and X-ray diffraction (XRD) researches of a surface morphology demonstrated a strong influence of deposition procedure parameters on the film microstructure. The XRD analysis revealed that all grown films were polycrystalline and single-phase. The increase of the gas ratio Ar/O2 was found to be beneficial for the crystalline structure of Zn0.9Cd0.1O ternary alloys. Peculiarities of the control over the band gap and the surface morphology for Zn0.9Cd0.1O ternary alloys by varying the growth parameters are discussed.Дослiджено вплив потужностi магнетрона i спiввiдношення тискiв робочих газiв Ar/O2 на мiкроструктуру та оптичнi властивостi плiвок Zn0.9Cd0.1O. Плiвки осаджено методом магнетронного розпилювання на постiйному струмi при температурi пiдкладки 250 C. Дослiдження морфологiї поверхнi, здійснені за допомогою атомно-силової мiкроскопiї (АСМ), i рентгено-фазовий аналiз (РФА) виявили сильний вплив технологічних параметрiв осадження на мiкроструктуру плiвок. РФА аналiз показав, що всi вирощенi плiвки є полiкристалiчними i однофазними. Встановлено, що зростання парцiального тиску аргону в газовiй сумiшi Ar/O2 сприятливо впливає на кристалічну структуру твердих розчинiв Zn0.9Cd0.1O. Обговорено особливостi контролю ширини забороненої зони та морфологiї поверхнi твердих розчинiв Zn0.9Cd0.1O шляхом змiни параметрiв вирощування.В работе исследовано влияние мощности магнетрона и соотношения давлений рабочих газов Ar/O2 на микроструктуру и оптические свойства пленок Zn0.9Cd0.1O. Пленки осаждены методом магнетронного распыления на постоянном токе при температуре подложки 250 C. Исследования морфологии поверхности, проведенные с помощью атомно-силовой микроскопии (АСМ), и рентгенофазовый анализ (РФА) выявили сильное влияние технологических параметров роста на микроструктуру пленок. РФА анализ показал, что все выращенные пленки являются поликристаллическими и однофазными. Было установлено, что рост парциального давления аргона в газовой смеси Ar/O2 благоприятно влияет на кристаллическую структуру твердых растворов Zn0;9Cd0;1O. Обсуждены особенности контроля ширины запрещенной зоны и морфологи поверхности твердых растворов Zn0;9Cd0;1O путем изменения параметров осаждени

Optical and structural studies of phase transformations and composition fluctuations at annealing of Zn₁₋xCdxO films grown by dc magnetron sputtering

Ternary Zn₁₋xCdxO (x < 0.12) alloy crystalline films with highly preferred orientation (002) have been successfully deposited on sapphire c-Al₂O₃ substrates using the direct current (dc) reactive magnetron sputtering technique and annealed at temperature 600 °C in air. The structural and optical properties of Zn₁₋xCdxO thin films were systematically studied using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), micro-Raman and photoluminescent (PL) spectroscopy. XPS measurements clearly confirmed Cd incorporation into ZnO lattice. XRD data revealed that the growth of wurtzite Zn₁₋xCdxO films occurs preferentially in the (002) direction. Also, when the Cd content is increased, the XRD peaks shift towards smaller angles and the full width at half-maximum of the lines increases. When the Cd content increases, LO A1 ( Zn₁₋CdxO )-like Raman modes show composition dependent frequency decrease and asymmetrical broadening. The near band-edge PL emission at room temperature shifts gradually to lower energies as the Cd content increases and reaches 2.68 eV for the highest Cd content (x = 0.12). The analysis of NBE band emission and Raman LO A1 ( Zn₁₋xCdxO ) mode shows that at a higher Cd content the coexistence of Zn₁₋xCdxO areas with different concentrations of Cd inside the same film occurs. The presence of CdO in annealed Zn₁₋xCdxO films with the higher Cd content was confirmed by Raman spectra of cubic CdO nanoinclusions. The XRD data also revealed phase segregation of cubic CdO in annealed Zn₁₋xCdxO films (Tann = 600 °C) for x ≥ 0.013

Isolation of two strains of West Nile virus during an outbreak in southern Russia, 1999.

From July to September 1999, a widespread outbreak of meningoencephalitis associated with West Nile virus (Flavivirus, Flaviviridae) occurred in southern Russia, with hundreds of cases and dozens of deaths. Two strains of West Nile virus isolated from patient serum and brain-tissue samples reacted in hemagglutination-inhibition and neutralization tests with patients' convalescent-phase sera and immune ascites fluid from other strains of West Nile virus

Spectral classification of O–M stars on the basis of


A new technique allowing the Q-method to be used surely for both the spectral classification of young O–A0 stars and older spectral subclasses A1–M5 is described. Characteristics of interstellar light absorption dependence on distance in the given direction of the sky is used as a main criterion for excluding possible multiplicity of star spectral estimates at some constant values of QUBV. Information on open cluster membership probabilities is also useful as additional criterion of the spectral classification. The method was tested on stars up to $V=14$ mag in directions of young open clusters NGC 2244 and NGC 2264. The spectral study based on UBV photometry was extended to faint stars of NGC 2264 in the V magnitude range 17-22 mag.


METHODS OF EVALUATION OF THE STATE AND EFFICIENCY OF THE URBAN ENVIRONMENT

Today, humanity is experiencing an "urban age", and therefore issues of good management of energy consumption and energy spent on utilization of waste in cities are becoming particularly acute. In this regard, the working group of the World Energy Council proposed a concept of the "energy balance" of the urban environment. This concept was that the energy produced should cover the energy consumed. Metabolism of the urban environment is so hot and so rarely studied by urban planners. This condition is linked first with the fact that metabolism is nothing more than a network of exchange of physical, energy resources and information. This is the real point of meeting the natural, technological, social, economic processes and their transformation into one another. Metabolism is the most important tool for knowing the real mechanics of the movement of resources in such a complex system as the urban environment. The content of the article is an analysis of significant energy and material flows characterizing the metabolism of the urban environment. We considered in the article a new energy paradigm. This paradigm will help in carrying out research in such areas as reducing the burden on the state of the environment, reducing environmental problems and reducing dependence on fossil fuels. Methods and models of metabolic processes in the urban environment will allow to implement in practice the concept of sustainable development of the urban environment, which is the development of the teaching V. Vernadsky about the noosphere

XPS and Raman Characterizations of Zn1−xCdxOZn_{1-x}Cd_{x}O Films Grown at the Different Growth Conditions

X-ray photoelectron spectroscopy was employed to characterize the surface chemistry and electronic properties of the $Zn_{1-x}Cd_{x}O$ semiconductor systems obtained at the different growth conditions. The effect of the growth conditions on the core and valence band spectra as well as room-temperature photoluminescence of the $Zn_{1-x}Cd_{x}O$ films was investigated and discussed. Behavior of the X-ray photoelectron spectroscopy peaks indicated an increase of the cadmium and a depletion of the oxygen concentrations upon changing the Ar/$O_2$ gas ratio and dc power

Copyright: Elsevier

Microstructure and luminescence dynamics of ZnCdO films with high Cd content deposited on different substrates by DC magnetron sputtering metho

ПЕРСПЕКТИВИ СТВОРЕННЯ УЛЬТРАФІОЛЕТОВИХ ФОТОРЕЗИСТОРІВ НА ОСНОВІ ПЛІВОК ZNO

Undoped and nitrogen doped n-ZnO films were deposited on Si and SiNx/Si substrates by magnetron sputtering. The methods of thermal vacuum deposition and standard LIFT-OFF lithography were used for fabrication ohmic In and Al contacts to ZnO. The influence of crystal perfection for undoped ZnO films and magnitude of interelectrode spacing of contacts on photosensitivity and response speed of the photoresistors on their basis were investigated. For photoresistors based on undoped films the photocurrent-to-dark current ratio equal to 24 at response speed about ten minutes were achieved. The photoresistors based on nitrogen doped films showed the photosensitivity with photocurrent-to-dark current ratio is equal to 250 at λ = 390 nm with time constant of photoresponse about 10 μs.Нелегированные и легированные азотом пленки n-ZnO осаждены на Si и SiNx/Si подложки методом магнетронного распыления. Методы термического вакуумного осаждения и стандартной LIFT-OFF литографии применены для нанесения омических In и Al контактов к ZnO. Исследовано влияние кристаллического совершенства нелегированных пленок ZnO и величины межконтактного расстояния на фоточувствительность и быстродействие фоторезисторов на их основе. Для фоторезисторов на основе нелегированных пленок была достигнута кратность 24 при быстродействии порядка десяти минут. Фоторезисторы, созданные на основе легированных азотом пленок ZnO, продемонстрировали фоточувствительность с кратностью 250 при λ = 390 нм и быстродействие с постоянной времени 10 мкс.Нелеговані та леговані азотом плівки n-ZnO осаджено на Si та SiNx/Si підкладки методом магнетронного розпилення. Для нанесення омічних In та Al контактів до ZnО застосовані методи термічного вакуумного осадження та стандартної LIFT-OFF літографії. Досліджено вплив кристалічної досконалості нелегованих плівок ZnО та величини міжконтактно ї відстані на фоточутливість та швидкодію фоторезисторів на їх основі. Для фоторезистор ів на основі нелегованих плівок досягнута кратність 24 при швидкодії порядку десяти хвилин. Фоторезистори, створені на основі легованих азотом плівок ZnO, продемонстрували фоточутливість з кратністю 250 при λ = 90 нм та швидкодію зі сталою часу 10 мкс