The metal–silicon thin−film system is not isostructural and furthermore exhibits pronounced interdiffusion and chemical reactions. Therefore the growth of metallic films on silicon leads to a high concentration of defects in the film, especially at its substrate interface. The material also contains stress and a transition layer consisting of melts or compounds (silicides).

We have considered theoretical viewpoints and reviewed experimental data on the growth and properties of metallic nanofilms (including multilayered ones) on silicon, and also provided a brief review of their applications. The films consist either of atomic−sized, quabquantum sized and quantum sized layers. We have suggested a low temperature film growth technology based on freezing growing layers during deposition by maintaining a low temperature of the substrate and using an atomic beam with a reduced heat power. The technology uses a specially shaped deposition system in which the distance between the source and the substrate is comparable to their size or smaller. Furthermore, we use a special time sequence of deposition that provides for a reduced substrate surface temperature due to greater intervals between deposition pulses. This growth method of atomically thin films and multilayered nanofilms excludes interdiffusion between the layers, reduces three−dimensional growth rate and relatively increases lateral layer growth rate.

For the first time silicon was grown by means of directional crystallization and using the submerged into the melt heater multi−crystalline. To study interaction of the heater casing material with molten silicon we used the model of the heater in the form of a graphite plate coated with a protective layer of SiC of the special structure. During the crystallization, the plate was on the melt surface and almost completely overlaid the surface of the melt, thereby significantly reducing the intensity of gas exchange between the melt and the atmosphere in the furnace. The absence of a free surface of the melt resulted in the absence of Marangoni convection, and the crystal grew under the conditions of reduced melt convection, especially at the final stages of crystallization, when the thickness of the melt layer was much less than the cross size of the crucible. The crystal structure has a strongly pronounced columnar structure; measured data on resistivity varies over the ingot height from 1 to 1.3 Ω⋅cm, and the lifetime of minority carriers is about 3.7 µs. FTIR studies of a carbon content showed the longitudinal distribution to fundamentally differ from the linear dependence typical for the method of directional crystallization.

In the close future, use of SoG should become prominent for photovoltaic ingot production as it requires much less energy for purification compared to Silicon grades using gas transformation and purification (usually Siemens process or equivalent also used for electronic−grade preparation). During this study, several kinds of silicon were compared with different rates of dopant content (mainly boron and phosphorus). Ingot yield and cell efficiency were optimized for each source of silicon at a production level (450 kg ingots) using boron or gallium doping. Starting from the resistivity specification given by the cell process, the doping level was adjusted in order to maximize the ingot silicon yield (weight of silicon bricks used for wafer cutting/ weight of Silicon ingot). After doping adjustment, ingot quality was checked: brick resistivity, lifetime of minority carriers and wafers were processed into solar cells. Optimizing of doping led to get comparable ingot yields and cell efficiencies using SoG and silicon purified by Siemens process or equivalent. The study was implemented at Kazakhstan Solar Silicon plant in Ust−Kamenogorsk using Kazakhstan SoG, SoG from a European manufacturer and polycrystalline Silicon purified by Siemens process. Directional solidification furnaces were manufactured by the French company ECM Technologies.

Promising absorbing materials along with Ni−Zn−ferrites are Mg—Zn−ferrites, as they are also intensively absorb electromagnetic waves in the frequency range from 50 MHz to 1000 MHz. The main advantage of the Mg−Zn−ferrite is that it is an inexpensive raw material magnesium oxide. The aim of this work was to study the effect of alloying elements — TiO2 and Bi2O3, — as well as impurities on the microstructure and properties of radar Mg—Zn−ferrite. The influence of alloying elements and impurities on the magnetic and dielectric constant of Mg—Zn−ferrite absorbing materials has been revealed. The addition of bismuth oxide causes a reduction of the permittivity and permeability Mg—Zn−ferrite in the range of up to 1000 MHz. Addition of titanium oxide increases the dielectric constant in the range of up to 1000 MHz, which is important to reduce the wavelength of radar ferrite materials. Addition of titanium oxide leads to a frequency shift of the absorption Mg—Zn−polycrystalline ferrite material towards lower frequencies, and bismuth — towards high frequencies.

Thus, the dopant can be regarded as a tool to regulate the wavelength range of the absorption of radar and ferrite materials.

Quantitative X−ray topography of GaSb : Te crystal, grown during unmanned Chinese space experiment has showed a high structural perfection in its greater area, which corresponds to the crystallization of a rounded interface. At the same time, the defects in the field of a face growth have been revealed after some time of the crystallization onset. The control of parameters during the growth process was absent. It was a reason for a reconstruction of the crystal growth history using a two−dimensional map of the measured Te concentrations in the crystal and mathematical modeling of the growth process, and taking into account the analysis of possible factors that influenced the growth crystal characteristics.

One−sided heating of plate with a free surface with continuous laser emission has been examined within the framework of quasistatic unbound problem of thermoelasticity. The method for determination of nondestructive conditions of laser annealing of dielectric and semiconductor plates has been validated. This relationship allows one to generate nondestructive conditions of laser processing. The calculation model has been obtained in the assumption of the independence of thermal, mechanical and optical properties of materials on temperature. We show that for a number of dielectric and semiconductor materials there is a region of change of the dimensionless parameter τ, in fracture of plates of these materials during laser annealing may occur due to thermoelastic stresses. Experimental verification of the adequacy of the calculation model has been made for the example of LK3 optical glass which showed quite a satisfactory agreement between the calculated and experimental data.

Dislocation pileups play an important role in the formation and propagation of strain in single crystals and polycrystals. They are the main source of cracking. Dislocation pileups are often referred to as the cause of serrated plastic strain pattern and degradation of the external quantum efficiency of UV LEDs. A dynamic physical model describing the formation of dislocation pileup by Frank–Read source has been presented that allows characterizing not only the structure but also time parameters of pileups. We provide data on the dislocation pile−ups e.g. dislocation configuration in a pileup, number of dislocations in a pile−up as a function of external stress, formation time of new dislocation loops and time to source blocking by the opposite strain generated by pileup dislocations. We compare our experimental results for pileups formed by Frank–Read source with results for pileups of straight edge dislocations. A large calculation effort is required to take into account the interaction of pileup dislocations. To accelerate our calculations we conducted them in parallel runs using a Т−Edge−10 38−nuclei cluster.

AlGaN/GaN heterostructures grown by MOCVD method on sapphire and silicon substrates were test subjects. The capacity− voltage characteristic measurements have been run in 200Hz — 1MHz frequency range at planar disposition of mercury and second probe on the sample surface. The shape of typical C−V curves for the heterostructures with the upper undoped i−AlGaN and i−GaN layers at thickness 15—25 A have been analyzed. The appearance of a typical peak on the C−V curves at changing from depletion region to accumulation region has been registered for some structures with thickness of i−GaN layer 50A at low frequencies (f < 50—200 kHz). The height of this peak increased with reduction of frequency. It has been found experimentally that frequency at which the peak is registered can depend on the dislocation density in heterostructures. Possible explanation of the peak formation and band diagram modifications in these structures under an applied electric field have been presented. We show that using a Si3N4 passivation layer results in the formation of additional positive charge.

Photoluminescence with the peak corresponding to yellow light in the visible spectrum (the so−called yellow luminescence) is generated by deep levels in the buffer GaN layer of the ehterostructures and depeonds on heterostructure growth conditions. In turn, the deep levels affect the resistivity of the ohimic contacts of RF transistors based on these heterostructures. This determines the reliability of GaN HF transistor operation. Two types of instruments have been developed for controlling photoluminescence with the peak in the yellow spectral region for characterizing the quality of AlGaN/GaN/SiC and AlGaN/GaN/Al2O3 heterostructures. One of them provides for rapid control of yellow photoluminescence and the other allows mapping of photoluminescence across the heterostructure area. Examples of photoluminescence maps for experimental structures grown on different substrates have been given.

21 апреля 2015 г. исполнилось 75 лет со дня рождения и более 50 лет практической, научной и педагогической деятельности широко известного специалиста в области физики и технологии тонких пленок, профессора, доктора технических наук, академика РАЕН Геннадия Дмитриевича Кузнецова.

3 мая 2015 г. видному ученому, крупному специалисту в области материаловедения и технологии ферритовых материалов, доктору технических наук, профессору Леониду Михайловичу Летюку исполнилось бы 80 лет.

«Инженер от Бога! Свидетель становления всех технологий... Великолепный организатор… Человек, знающий, что и когда надо делать», — так говорили о профессоре Всеволоде Валерьевиче Крапухине его коллеги по работе, друзья.