Photosensitive silicon/barium titanate/nickel structures with undoped barium titanate and doped europium were synthesized using the sol-gel method. The current-voltage characteristics were studied under illumination with a xenon lamp, highlighting a monochromatic line in the range of 400–800 nm and in dark mode. The synthesized structures showed the presence of a photocurrent on the reverse branch of the current-voltage characteristics over the entire studied range of illumination wavelengths. The maximum reverse branch current for a structure with undoped barium titanate was achieved when exposed to radiation with a wavelength of 470 nm and was about 0.6 μA for a bias voltage ranging from 2 to 10 V. Doping barium titanate with europium leads to an increase in the photocurrent by 17–26 %.

Film structures based on Si1–xGex (0 < x < 1) solid solutions are currently obtained by chemical-vapor-deposition methods. For device application of the obtained structures, it is necessary to know the electrical properties of the material synthesized under different conditions. In this work, we carry out galvanomagnetic studies of the electrical conductivity in porous and solid Si1–xGex films, as well as the concentration and mobility of the majority charge carriers in them at a temperature of 30–300 K. It is shown that, as in pure silicon and germanium of comparable porosity, the electrical conductivity in the studied samples can be considered as in a medium with voids. It is established that the type of majority charge carriers in the alloy is determined by the type of silicon substrate used. This is practically important for creating both arms of a thermoelectric converter, which makes the method for producing Si1–xGex(0 < x < 1) alloy promising for device applications, in particular in thermoelectric converters and lithium-ion batteries.

Equivalent electrical circuits of multilayer film structures with memristor switching of resistance at interlayer boundaries and at the boundaries of crystal grains in each layer are proposed. Numerical modeling of the current-voltage characteristics of such structures has shown that their loop-shaped form, typical of memristors, is transformed into a linear ohmic dependence of the total current on the magnitude of the applied external voltage as both the number of layers and the number of grains in each layer increase. A certain combination of the number of layers and grains in a layer has been established, at which the maximum total current flowing through the structure and the ratio of resistances in the “off” and “on” states reach the highest values.

This work experimentally and theoretically analyzes the dynamics of the process of ion emission from a capillary emitter filled with an ionic liquid as a working fluid. Such emitters can be used in the energy system of low-mass satellites as a source of jet propulsion. The dependence of the thrust of a micromotor on the electrical power supplied to it was experimentally studied, which made it possible to determine the most efficient operating modes of the microthruster. This is of interest from the point of view of increasing the energy efficiency of the latter in conditions of limited power availability of low-mass satellites. It was found that the characteristic “electric field voltage – emitter thrust” is non-monotonic with a pronounced maximum, which imposes restrictions on the magnitude of the electric field in the emitter. To explain the limit of emission intensity, a diffusion-convective model of ion movement inside the capillary was constructed. The main idea of the proposed model is the assumption that the intensity of ion emission is determined by their concentration at the outlet of the capillary, and the velocity of the emitted ions is higher than the velocity of flow of the ionic liquid in the capillary as a continuous medium. Moreover, the acceleration of ions at the outlet of the emitter increases nonlinearly with increasing external forces. The decrease in the concentration of ions as they are emitted must be compensated by their diffusion inside the capillary and convective flows, the velocity of which is limited. The constructed system of equations is analyzed numerically. For the system of Navier – Stokes equations, the projection method proposed by Chorin is applied. Based on the known velocity field, density, and concentration distribution, a time step is taken for the equations of motion. Then, taking into account the found velocity, a time step is taken for the convective diffusion equations and the density field is recalculated. The created code made it possible to confirm the possibility of the existence of a maximum mass flow rate of ions, i.e., micromotor thrust, which is in qualitative agreement with the experimental data. The main factor on which the magnitude of the maximum and its position depend is the degree of nonlinearity of the coefficient responsible for the acceleration of ions at the outlet of the capillary.

By combining sol-gel and hydrothermal deposition methods on glass substrates, thin-film coatings of zinc oxide doped with nickel and aluminum were obtained. Studies of the structure and composition of the films using scanning electron microscopy, energy-dispersive X-ray and Raman spectroscopy have shown that they consist of close-packed zinc oxide crystallites doped with impurity atoms of nickel and aluminum. Resistive type photodetectors were manufactured based on the films obtained. It has been shown that when irradiated with ultraviolet light with a wavelength less than 400 nm, the resistivity of the structure decreases from 190–210 to 7.5–8.0 Ohm⋅cm. The achieved response time for the rise of the light pulse is 48 s, while the decay time is ≈700 s.

The recent results of the investigations performed in the research units of the Department of Micro- and Nanoelectronics of Belarusian State University of Informatics and Radioelectronics in the field of the development of perspective optical and electronic intra-chip and inter-chip interconnections of silicon integrated circuits are summarized. Examples of the use of nanostructured materials for the proposed light sources and detectors (Si) as well as light guides (Al2O3/TiO2) integrated with monocrystalline silicon are presented. The strategy of an application of inter-chip interposers for optical and electronic connections in bulk (2.5D and 3D) packages of integrated circuits was promoted and tested. Novel materials and structures promising for light sources, optically transparent electrical conductors and protectors against microwave electromagnetic radiation are demonstrated.

Al/g-C3N4/Si/Al, Al/g-C3N4/SiO2/Si/Al, Al/g-C3N4/Al and Al/g-C3N4/Al2O3/Al structures were fabricated by rapid chemical vapor deposition of graphitic carbon nitride (g-C3N4) from melamine onto silicon (Si) and aluminum (Al) substrates partially coated with appropriate oxide – SiO2 or Al2O3 – and Al contacts deposited on the surface. Their capacitance-voltage characteristics and frequency dependence of the capacitance were measured at room temperature. It was found that the permittivity of g-C3N4 is 14 in structures on silicon and 9–10 in structures on aluminum. The decrease in permittivity is explained by the formation of Al2O3 at the g-C3N4/Al boundary during the deposition of g-C3N4, as indicated by the results of the X-ray diffraction analysis of the formed samples.

The synthesis of a composite material based on graphitic carbon nitride by pyrolytic decomposition at 550 °C of a mechanical mixture of thiourea with the addition of aluminum powder in the amount of 5–30 wt.% has been studied. According to the scanning results by means of electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry the synthesized material consists of carbon nitride, aluminum sulfide, residual metallic aluminum and aluminum hydroxide. The excess of metallic aluminum is due to the partial interaction with sulfur-containing volatile substances formed during the thermal decomposition of thiourea. It is shown that the intensity and width of the photoluminescence spectra of the synthesized composites are determined by the aluminum concentration in the initial mixture. As the aluminum concentration increases from 5 to 30 wt.%, the photoluminescence intensity maximum shifts to the long wavelength region from 534 to 560 nm. This can be used to create optoelectronic devices based on the graphitic carbon nitride.

Electric properties of film structures consisting of two-dimensional layers , composed by nanocrystalline grains of a semiconductor are proposed to be modeled with an equivalent scheme , in which resistors indicate electrical resistance of current channels in metallic contacts , grain material , potential barriers between grains and layers . Numerical simulation within the model has shown that there is a nonuniform current distribution over the area of the contacts . Current density at their edges can be 3–6 times higher than in the center . Local currents and their distribution in the film bulk are determined by the grain structure of the film , number of the layers , electronic properties of the barriers between grains and layers .

In this work, sol-gel synthesis and luminescence properties of erbium and ytterbium doped BaTiO3 (BaTiO3:Er,Yb) in porous anodic alumina are reported. Porous anodic alumina with its well-known tailor-made honeycomb structure was chosen as a template for the sol-gel synthesis of BaTiO3:Er,Yb. Porous anodic alumina was fabricated either on silicon wafer or aluminum foil. The sol corresponding to xerogel content of Ba0,76Er0,04Yb0,20TiO3 was deposited on porous anodic alumina by spinning, which was followed by drying and heat treatment at a relatively low temperature 450 °C on aluminum foil or 800 °C on silicon. Porous anodic alumina known also as an optically anisotropic structure differed in the experiments by diameter of the pores and thickness. Evidently, all fabricated samples demonstrated a roomtemperature erbium upconversion luminescence under excitation in the continuous-wave (CW) mode with a focused 980 nm laser beam of a 200 mW diode module. Erbium upconversion luminescence is characterized by the bands at 410, 523, 546, and 658 nm, corresponding to the 2H9/2 → 4I15/2, 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2.

Using differential thermal analysis and thermogravimetry, we have studied thermal decomposition of a mechanical mixture of thiourea and zinc acetate, resulting in the formation of a composite material consisting of graphitic carbon nitride and zinc acetate, g-C3N4/ZnS, and possibly containing zinc oxide (ZnO) inclusions. In the case of a mixture containing the stoichiometric sulfur : zinc ratio for zinc sulfide synthesis, one can obtain a material containing only ZnS semiconductor crystals embedded in a g-C3N4 matrix. ZnS is formed in the temperature range 317–367°C as a result of decomposition of zinc complexes with thiourea. Heating the mixture to above 560°C increases the rate of the thermal decomposition of g-C3N4, which reaches completion between 720 and 740°C. The presence of oxygen in the reaction atmosphere also accelerates this process, without significantly changing the temperature range of synthesis or decomposition of reaction products. The proposed technique can be used for the synthesis of g-C3N4-based composite materials and other semiconducting metal sulfides.

Erbium-doped barium titanate (BaTiO3:Er) xerogel film with a thickness of about 500 nm was formed on the porous strontium titanate ([Formula: see text] xerogel film on Si substrate after annealing at 800[Formula: see text]C or 900[Formula: see text]C. The elaborated structures show room temperature upconversion luminescence under 980 nm excitation with the photoluminescence (PL) bands at 523, 546, 658, 800 and 830 nm corresponding to 2[Formula: see text]4[Formula: see text], 4[Formula: see text][Formula: see text], 4[Formula: see text][Formula: see text] and 4[Formula: see text]4[Formula: see text] transitions of trivalent erbium. Raman and X-ray diffraction (XRD) analysis of BaTiO3:Er\porous SrTiO3\Si structure showed the presence of perovskite phases. Its excellent up-conversion optical performance will greatly broaden its applications in perovskite solar cells and high-end anti-counterfeiting technologies.

Films of cobalt oxide and nickel oxide on monocrystalline silicon substrates were obtained by electrochemical deposition from aqueous electrolyte solutions. Their structure and composition were studied by Raman microscopy and scanning electron microscopy. The results of the study by Raman spectroscopy showed that the obtained films are polycrystalline structures of cobalt (II, III) oxide and nickel (II) oxide, the crystalline perfection of which increases with an increase in the electrolyte temperature. It was found by scanning electron microscopy that nickel oxide films have a smoother surface, while cobalt oxide has a more developed structure consisting of lamellar crystals. The specific electrochemical capacity of cobalt oxide and nickel oxide films obtained under optimal conditions, measured by voltammetry, was 14.67 and 1634.08 F/g, respectively. The high specific electrochemical capacity of a nickel oxide film can be used to create efficient electrochemical devices and energy storage devices.

In this work, we propose a new, previously unpresented in the literature, approach to the formation of Si1-xGex films. This approach includes electrochemical processes of the formation of porous silicon, electrochemical deposition of low-melting metals and Ge. Post-heat treatment is made possible to synthesize film structures based on Si1-xGex solid solutions. Using this approach an alloy of the composition Si0.4Ge0.6 has been obtained at a lower formation temperature than predicted by the phase diagram for the Si-Ge system.

The possibility of pyrolytic synthesis of composite heterosystems based on macroporous silicon, graphitic carbon nitride and wide band semiconductors zinc oxide and zinc sulfide (g-C3N4/ZnO/ZnS) from a mechanical mixture of thiourea and zinc acetate at 500 – 600 °C was shown. The obtained material study by scanning electron microscopy and energy dispersive X-ray spectroscopy showed a uniform filling of macroporous silicon with the composite g-C3N4/ZnO/ZnS with the formation of a continuous composite film on the surface. The photoluminescence of the samples was controlled by the synthesis temperature. Increase of photoluminescence leads to shift of luminescence maximum in high energy range from 544 to 516 nm. It was found that photocatalytic activity of composite heterosystems obtained at a lower temperature is higher due to more developed surface morphology and smaller bandgap width. The materials obtained can be used to create photocatalytic coatings and functional layers of optoelectronic devices.

A ternary heterosystem consisting of crystalline graphitic carbon nitride, zinc oxide, and zinc sulfide (g-C3N4/ZnO/ZnS) was obtained by the one-stage decomposition of a mixture of thiourea and zinc acetate. The integral toxicity index of the resulting material was estimated in a luminescent test with a genetically modified Escherichia coli strain as a test object. The effect of quenching the luminescence of E. coli was noted both under exposure to UV radiation due to photocatalytic reactions on the surface of g-C3N4/ZnO/ZnS leading to the formation of highly oxidative radical ions interacting with cell membranes and without irradiation due to mechanical interactions with bacterial cells. At a 0.3 g/L concentration of g-C3N4/ZnO/ZnS in aqueous solution, the toxicity index T reached 75.6% under UV irradiation. In this case, an increase in the toxicity index T of the ternary heterosystem in a test concentration range from 0.1 to 0.3 g/L was 6 or 10–11% under UV radiation or without illumination, respectively, as compared with that of the pure graphite-like carbon nitride obtained under identical conditions.

The regularities of composition changes of silicon/germanium alloy thin films formed on a monocrystalline silicon substrate by electrochemical deposition of germanium into a porous silicon matrix with subsequent rapid thermal annealing (RTA) at a temperature of 750–950°C are studied. An analysis of the samples by Raman spectroscopy showed that an increase of RTA temperature leads to a decrease in the germanium concentration in the formed film. A decrease of the RTA duration at a given temperature makes it possible to obtain films with a higher concentration of germanium and to control the composition of thin silicon/germanium alloy films formed by changing the temperature and duration of RTA. The obtained results on controlling the composition of silicon/germanium alloy films can be used to create functional electronic devices, thermoelectric power converters, and optoelectronic devices.

It is concluded that oxidation of porous silicon in an air atmosphere at 300 ° C or in an aqueous solution of nitric acid (50 vol.%) can drastically improve the filling of pores by indium during its subsequent electrochemical deposition. Due to the oxidation of the porous skeleton’s topmost areas, the maximum concentration of indium is shifted from the surface deeper into the pore channels. This effect is especially apparent in the case of oxidation via nitric acid, whereat the maximum relative concentration of indium inside the pores is achieved.

We have found one step synthesized g-C3N4/ZnO/ZnS composite to be promising for engineering of white-light sources. The composite was fabricated by simultaneous pyrolytic decomposition of thiourea and zinc acetate with a consequent in situ polymerization of the products at 550-625 degrees C and characterized by SEM, XRD, EDX and low temperature PL spectroscopy. The composite synthesized at 550 degrees C demonstrates blue PL with a peak at 2.74 eV while higher temperatures of the synthesis result in a broad spectra with a maximum at 2.22 eV and comprise of the bands of g-C3N4 and mixed ZnO/ZnS as they have been resolved by low temperature PL. The proper selection of the synthesis temperature allows an extension of light emitting spectra of g-C3N4/ZnO/ZnS composites from blue to white light range. The results obtained show ternary systems containing g-C3N4 and wide band-gap semiconductors are suitable for white-light emitting and optoelectronic devices.