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[en] The formation of nanostructures on the surface of GaAs under quasi-equilibrium conditions in a quasi-closed volume from saturated phosphor and indium vapors in the presence of a Au catalyst with growth according to the “vapor–liquid–crystal” mechanism is considered for the first time. The influence of the growth temperature and size of Au drops on the morphology and composition of the fabricated nanostructures is studied. Experimental data on the formation of Ga(In)AsP nanocrystals on GaAs substrates with various orientations are presented. It is established that the temperature growth range of the nanostructures when using this method is 540–640°C with a drop size from 30 to 120 nm. It is shown that the size of the catalyst drops substantially affects the morphology and growth rate of the fabricated nanostructures while their composition weakly depends on both the drop size and the substrate orientation.

[en] Reflection of infrared radiation from n-InP substrates with a rear MgF₂/Au mirror is investigated in the wavelength range 1000-2200 nm. It is found that the reflectance weakly depends on substrate thickness and free-carrier concentration in the (0.1-6) x 10¹⁸ cm^-3 range. Thermophotovoltaic cells based on the InP/In_0.53Ga_0.47As lattice-matched heterostructure of p-n and n-p are fabricated by liquid-phase epitaxy and Zn and P diffusion from a gas phase. The characteristics of p-n and n-p thermophotovoltaic cells with an identical configuration of the contacts of 1 cm² area are determined. These characteristics are the open-circuit voltage U_oc = 0.465 V, the filling factor FF = 64% at the current density of 1 A/cm², and the reflectance R = 76-80% for wavelengths longer than 1.86 μm

[en] The results of studies of the surface of GaAs in the presence of indium and phosphorus surfactants are reported. It is shown that, as a result of their diffusion (annealing) at a temperature of 650–670°C, clusters enriched with indium are formed in the GaAs surface region. The clusters can be seen as bright spots in an image obtained by a scanning electron microscope with the use of an in-lens detector. At the same time, studies of the morphology of this surface with an atomic-force microscope show a decrease in the root-meansquare roughness of the surface after annealing (diffusion), which is indicative of the incorporation of In atoms into the GaAs crystal lattice. The clusters are responsible for changes in the Raman spectra. Specifically, an increase in the signal intensity due to surface-enhanced Raman scattering and a shift of the vibration frequency in the surface region are observed. It is found that cluster formation is defined by the crystallographic orientation of the surface and by the technological conditions of surface preparation.

[en] A solar TPV generator development and characterization are presented. A double stage sunlight concentrator ensures 4600x concentration ratio. TPV modules based on tungsten emitters and GaSb cells were designed, fabricated and tested at indoor and outdoor conditions. The performance of tungsten emitter under concentrated solar radiation was analyzed. Emitter temperatures in the range of 1400-2000 K were measured, depending on the emitter size. The light distribution in the module has been characterized, 1x1 cm GaSb TPV cells were fabricated with the use of the Zn-diffusion and LPE technologies. The cell efficiency of 19% under illumination by a tungsten emitter (27% under spectra cut-off at λ > 1820 nm) heated up to 1900-2000 K had been derived from experimentally measured PV parameters. The series connection of PV cells was ensured by the use of BeO ceramics. The possibilities of system performance improvement are discussed

[en] The comparative characteristics of photovoltaic converters (of laser radiation) based on gallium arsenide with a p-type emitter formed by gas-phase diffusion in the presence of surfactants (isovalent impurities) and without them are reported. It is shown that the use of indium and phosphorus in the process of the formation of a p#En Dash#n junction significantly affects the characteristics of the obtained devices.

[en] The article presents the problem formulation for diagnostics and optimal planning of the trajectory of the technological process taking into account the wear of the mechatronic systems and its electric motors. As an example, we consider a mobile robot with a differential drive, which must successively pass a field of various shapes. The trajectory of movement is chosen taking into account the wear of its electric motors. To solve this problem, it is supposed to use graph theory and probabilistic algorithms. Examples of solutions to the problem are given without taking into account the properties of the soil in the working space of the robot, used by the type of drive and its angle of rotation. The power of sets of feasible solutions will increase significantly with increasing number of technological operations, which, in turn, will lead to inefficiency of using brute force methods for solving the formulated problem and the need to solve it based on probabilistic algorithms agent metaheuristics. (paper)

[en] The question of minimizing the loss of the active component of power in power transformers of distribution networks is considered.Authors’ attention is focused on the reduction of additional losses due to the non-sinusoidal nature of the load. The proposed solution is based on the application of the principle of level decomposition for the system “digital substation - distribution network”. There are three logical levels distinguished, which are described in terms of the agent approach within the framework of this system. At the single-phase consumer level the solution of the combinatorial problem of dynamic connection of consumers by means of agent metaheuristics is offered. It is proposed to integrate an intelligent agent into the transformer substation. The main functions of the agent are to control the launch of agent metaheu-ristics and adaptive filtering of higher harmonic components of the current. Also, the integration of an intelligent agent is offered at the digital substation level. Its task is to synthesize a new configuration of the distribution network, subject to receiving information from agents of transformer substations. For the coordinated work of all agents, the organization of their interaction through a wireless network is proposed. (paper)

[en] Electrical supply sources based on photovoltaic converters and tritium radioluminescent lamps with blue and green glow are developed and fabricated. Al_xGa_{1 –x}As/n-GaAs p–n heterostructures with various band-gap widths (E_g = 1.4–1.9 eV) and compositions of the active region (x = 0.1–0.35) are prepared by low-temperature liquid-phase epitaxy. The photovoltaic converter with an area of S = 0.12 cm² upon irradiation by a green tritium lamp (wavelength λ = 550 nm) has the short-circuit current density 180 nA/cm² and output electrical power >100 nW/cm².

[en] We used a low temperature near-field scanning optical microscopy (NSOM) to study a formation of Wigner molecules (WMs) in the emission spectra of self-organized InP/GaInP QDs having up to seven electrons. We used a Schottky diode structure for the electrostatic control of the number of the electrons (N) in QD, and we observed the emission of the charged excitons (for N < 3) and of the WMs (for N > 2) in the regime of weak Wigner localization. We show, that a contribution of whispering gallery modes (WGMs) of the electrons and rearrangement of the electrons between the WM and WGM states in the QDs, can explain the anomalous dependence of NSOM image size on the quantum confinement observed for some dots.