The compaction kinetics, phase composition and mechanical characteristics of pure SiC and pure TiC ceramics, as well as SiC–TiC composite ceramics, obtained by spark plasma sintering (SPS), were studied depending on the component content and SPS-modes. It was found that at a fixed pressing pressure (PSPS = 45 MPa) in a given range of temperatures and sintering times (1800 ≤ TSPS ≤ 2000°C and 0 min ≤ tSPS ≤ 10 min), the relative density of sintered ceramics increases with increasing temperature and sintering time and reaches maximum values of 88, 99.9, and 96.2 of the calculated value for SiC, TiC, and SiC + TiC(10 wt

A comparative study of the growth processes, microstructures, and electrical characteristics of oxide/metal/oxide trilayer structures of different compositions synthesized at 50°C by rf magnetron sputtering in argon has been performed. The effect of subsequent annealing in an open atmosphere on the conductivity of the structures has been investigated. Transmission electron microscopy and energy-dispersive X-ray spectroscopy have been used to examine changes in the microstructure and profiles of distribution of chemical elements included in the structures under annealing. Based on the results obtained, mechanisms have been proposed for the transformation of interlayer interfaces and conditions of carrier transport in the structures, depending on the composition of the oxide and metallic layers comprising them.

The process of high-temperature oxidation of silicon carbide-based ceramic materials synthesized by spark plasma sintering without any sintering-activating additives has been studied. Analysis of the microstructure of the oxidized ceramic samples and the data on the change in their mass indicate the formation of a protective SiO2 layer on the SiC surface, which is characteristic of passive oxidation of silicon-containing oxygen-free compounds. The results of the comparative study of oxidation of the SiC ceramic samples with different porosity in air at a temperature of 1200°C have revealed a linear relationship between the growth rate of the oxidized sample mass and the volume of open pores in the sample.

SiC and TiC samples have been obtained by spark plasma sintering. The SiC ceramics samples have the main phase 6H-SiC (α-SiC) and low contents of SiO2 and 16H-SiC phases. Raman spectroscopy has shown the presence of free unbound carbon in them and a lower structural quality of the surface layer. The samples exhibit microhardness values typical of ceramics with similar porosity values. In turn, the TiC sample is characterized by low porosity, a uniform composition of cubic TiC phase, a small amount of free carbon, and a microhardness typical of TiC alloys. The results obtained allow one to speak about the applicability and prospects of the spark plasma sintering method in the synthesis of functional ceramics.

The features of aluminum localization and the mechanism of donor center formation in ZnO:Al layers synthesized by high-frequency magnetron sputtering are studied. It is shown that aluminum predominantly localizes at grain boundaries of zinc oxide in its own oxide phase. The mechanism of aluminum oxidation at grain boundaries significantly depends on the oxygen content in the working chamber: during sputtering in an atmosphere of pure argon under conditions of oxygen deficiency, aluminum oxidation occurs as a result of interaction with oxygen from the surface layer of zinc oxide crystallites, forming surface donor centers at grain boundaries. With an increase in the partial pressure of oxygen, aluminum is predominantly oxidized by oxygen from the gas atmosphere, forming its own barrier phase at grain boundaries.

Reducing the cost of the materials and technologies used to form functional films is one of the most pressing issues in the rapidly developing transparent electronics industry. In this regard, ZnO-based films deposited by magnetron sputtering are of particular interest, being considered as a real alternative to more expensive indium oxide films when forming transparent electrodes in various optoelectronic applications. However, the choice of optimal film’s compositions and formation modes for each specific application is complicated by the lack of systematic comparative data on these systems obtained under identical conditions. In this work, ZnO films doped with Al, Ga, and In at a level of 1 to 20 at.% were obtained under identical conditions by the magnetron sputtering method. The dependence of the structure and electrical characteristics of ZnO films on the dopant content and deposition temperature was studied. It has been established that the key factors determining the behavior of an impurity in a ZnO matrix are its chemical activity, solubility in the matrix, the ionic radius of the impurity metal in a given coordination, and the electrical characteristics of additional oxide phases of the doping element formed at grain boundaries.

Since the stability of functional properties of a transparent conducting three-layer structure ZnO:Ga/Ag/ZnO:Ga is important for practical application, we studied its long-term durability and thermal stability in air environment. It has been demonstrated that after prolonged interaction with the air environment at room temperature (for ~ 1000 days) and further heat treatment in air at temperatures of up to 450oC (for up to 10 h), the three-layer structure retains its integrity and is characterized by a low sheet resistance Rs=2.8 Ω/sq at average transmittance in the visible range Tav=82.1%. Keywords: transparent electrode, multilayer structure, ZnO, Ag, Ga, sheet resistance, transparence, stability, heat treatment.

Исследована стабильность поверхностного сопротивления и оптического пропускания трехслойных структур ITO/Ag/ITO, GZO/Al/GZO, а также тонкопленочной периодической структуры IZO с модулированным по толщине содержанием кислорода при 1000-часовых испытаниях в условиях влажности 85% и температуры 85 °С. Проведен анализ механизмов деградации структур в зависимости от состава и свойств единичных слоев.

Increasing the conductivity of transparent conductive layers by increasing the mobility of free charge carriers is one of the most important tasks of transparent electronics, since its solution contributes not only to the reduction of heat losses in the layers, but also to the expansion of the spectrum of the radiation used towards the near infrared region. Currently, work in this area is being carried out in some routes, one of which is the search for new layer's compositions that allow reducing the amount of impurity introduced while simultaneously increasing the efficiency of its ionization. In this paper, the influence of the oxygen content in the working gas and the deposition temperature on the morphology, microstructure, electrical, and optical characteristics of thin layers deposited by high-frequency magnetron sputtering of an ceramic target based on In2O3 with the addition of 1 wt.% WO3 was investigated. It was found that the maximum mobility (59 cm(2)/V center dot s) and minimum specific resistance (7,8x10(-4) Ohm center dot cm) are achieved in layers synthesized at 300 degrees C in the pure argon atmosphere. For comparison, layers based on a solid solution of indium and tin oxides, widely used in the formation of transparent electrodes in various optoelectronic applications, were obtained under identical conditions. It was shown that layers based on indium oxide doped with tungsten retain acceptable transparency in a wide spectral range, up to 2000 nm, and are, therefore, preferable for use in devices operating in the near infrared range, for example, in solar energy converters or night vision devices.

The specific features of aluminum localization and the mechanism of formation of donor centers in ZnO:Al layers synthesized by rf magnetron sputtering have been investigated. It is shown that aluminum is mainly localized on intergranular boundaries of zinc oxide in the intrinsic oxide phase. The mechanism of Al oxidation on grain boundaries depends strongly on the oxygen content in the working chamber: during sputtering in a pure argon atmosphere with oxygen deficit, aluminum oxidation occurs as a result of the interaction of the surface layer of zinc oxide crystallites with oxygen, which leads to the formation of surface donor centers on grain boundaries. With an increase in partial oxygen pressure aluminum is mainly oxidized by the oxygen from the gas atmosphere, forming an intrinsic barrier phase on grain boundaries.

Nonstoichiometric ZnO1-x phases with oxygen deficiency at grain boundaries (GBs) in polycrystalline ZnO layers are a typical damaged layer formed during the synthesis or subsequent storage. In this case, the processes of adsorption-desorption of gases are the basic phenomenon used in the analysis of gas composition. MGB layers also play an important role in creating transparent electrodes for transparent electronics and optoelectronics devices. This makes it relevant to study the generalization of research data on non-stechiometric structures in various applications. Purpose: the research carried out is devoted to the analysis of the formation processes of non-stoichiometric ZnO1-x surface phases in gas sensors, transparent electrodes, ceramic targets for magnetron sputtering, and in light-emitting structures. Research is aimed at finding ways to control and optimizing the parameters of non-stoichiometric ZnO1-x phases. The structural features, electrical, optical, and emissive properties of the layers were studied depending on the stoichiometry of the material. The issues of transformation of the structure of grain boundaries in ZnO-based polycrystalline layers depending on the formation conditions and external influences are considered. The relationship between the mechanisms of carrier transport and the processes of formation of nonstoichiometric phases on the MG has been studied. The dependences of the luminescence spectra of ZnO layers on the density of oxygen vacancies were traced. The regularities of the formation of energy structures of magnetic grains in ZnO layers are considered. Establishment of patterns of formation and characteristics of non-stoichiometric phases on the MGB during the formation of various modifications of transparent electrodes. Study of ways to optimize the parameters of surface non-stoichiometric layers.

A comparative study of the growth process of transparent conductive films based on Ga-doped ZnO is carried out during the magnetron sputtering of a traditional ZnO:Ga ceramic target and ZnO:Ga–Zn composite targets with a Zn metal phase content of 10 to 30 wt %. The influence of the composition of composite targets and substrate temperature on the functional characteristics and microstructure of transparent conductive films is studied. It is demonstrated that an increase in the zinc content in the composition of the composite target when the substrate is heated to 200°C and above helps to improve the structural perfection of ZnO:Ga films and reduce their resistivity due to an increase in the concentration of charge carriers against the background of a high value of Hall mobility. All ZnO:Ga films obtained by sputtering composite targets at a substrate temperature of 200°C and above demonstrate high optical transmittance in the visible region.

Аморфные прозрачные проводящие пленки с высокой подвижностью носителей заряда в

Проанализированы процессы магнетронного синтеза нанокристаллических и аморфных слоев на основе оксида цинка. Изучено влияние легирующих компонентов и уровня легирования на степень аморфизации слоев. Рассмотрено влияние водорода в составе атмосферы на структурное совершенство синтезируемых слоев. Показана зависимость структуры слоев ZnO–SnO2 от соотношения компонентов в распыляемых мишенях. Обсуждены механизмы формирования аморфных слоев на основе ZnO при магнетронных методах синтеза.

АннотацияЦель.Изучение процессов формирования, электрических и оптических свойств многослойных тонкоплёночных периодических структур на основе чередующихся слоёв нелегированного и легированного алюминием оксида цинка в зависимости от толщины единичных слоёв и температуры синтеза

Тонкопленочные конвертеры нейтронов на основе карбида бора B4C, обогащенного изотопом 10В, наносимые на подложки из алюминия, алюминиевой фольги и полимерных пленок большой площади, являются перспективным материалом для создания новых детекторов нейтронов. Нанесение пленок B4C методом магнетронного распыления на такие основания сильно осложняется необходимостью нагрева подложек до температуры 400 °С и более, что может приводить к их деформации. В работе показано, что применение ионного ассистирования в процессе магнетронного осаждения B4C приводит к формированию пленок нанокристаллической структуры, обладающих высокой прочностью и гибкостью, даже при понижении температуры подложки до 50 °С, а использование подслоя алюминия повышает адгезию. Получены тонкие пленки B4C на подложках из алюминия 0,5 × 100 × 100 мм2 и 0,5 × 280 × 400 мм2 в атмосфере аргона при температуре 400, 200 и 50 °С. Исследованы структура, состав и показатель преломления по пленкам на пластинах из кремния. Гибкость получаемых пленок и низкая температура формирования дают возможность нанесения конвертера нейтронов из 10B4C на тонкие полимерные основания.

Since to the stability of the functional properties of a transparent conducting three-layer structure ZnO:Ga/Ag/ZnO:Ga is important for practical application, we studied its long-term durability and thermal stability in air environment. It has been demonstrated that after prolonged interaction with the air environment at room temperature (~ 1000 h) and further heat treatment in air at temperatures up to 450 ° C (up to 10 h), the three-layer structure retains its integrity and is characterized by a low sheet resistance Rs = 2.8 Ω/sq at average transmittance in the visible range Tav of 82.1%.