Optical and electrophysical properties of Cz-grown zinc doped p-GaAs samples have been investigated. Middle-infrared reflection spectra of ten p-GaAs samples have been obtained. Galvanomagnetic Van der Pau measurements have been made on these samples also, and the values of resistivity and Hall coefficient have been calculated. All experiments have been carried out at room temperature.
Reflection spectra have been processed by Kramers–Kronig relations. The spectral dependences of real and imaginary parts of complex dielectric permittivity have been obtained and loss function has been calculated. The value of characteristic wave number corresponding to high-frequency plasmon-phonon mode has been determined by loss function maximum position.
The theoretical calculations have been made, and the dependence has been obtained which gave the possibility to determine heavy hole concentration value at T = 295K by the value of characteristic wave number. Then by comparison of optical and Hall data the values of light hole mobility to heavy hole mobility ratio have been determined. This mobility ratio has been shown to be equal to (1.9–2.8) which is considerably less, than predicted theoretical value based on assumption that both light and heavy holes are scattered by optical phonons. It has been suggested that scattering mechanisms of light and heavy holes might be quite different.

A large number of modern functional single crystals of the middle category belong to gyrotropic media. In these crystals, when light propagates along the optical axis, rotation of the plane of its polarization is observed. In this work a spectrophotometric method was used to obtain the dispersion dependences of the rotation angle of the polarization plane. This method is based on measuring the intensity of light passing through the polarizer–crystal–analyzer system, the crystal is a polished plane-parallel plate of a uniaxial gyrotropic crystal cut perpendicular to the optical axis. Measurements were carried out on a UV-Vis-NIR spectrophotometer Cary-5000 in the wavelength range of 200—1200 nm using polarizers — Glan–Taylor prisms. Polished plane-parallel plates of known SiO₂ and α-LiIO₃ crystals were used as samples. The obtained dispersion dependences of the spectral transmission coefficients are oscillating. Discrete values of the specific angles of rotation of the plane of polarization of light are calculated from the extremes on these dependencies. These discrete values can be approximated by the formulas Drude, Chandrasekhar and Vyshina, depending on what determines the nature of the rotational ability of the plane of polarization of light in each particular material. For the studied crystals, dependences of the modified Drude formula of the form 1/ρ = f(λ²) are plotted, these dependences should have a linear character in the case of an ideal crystal. The obtained experimental results correlate well with the available literature data. The advantages of this method are efficiency, the possibility of obtaining dispersion dependences of the specific rotation angle of the polarization plane, the need for a single sample, the possibility of assessing the nature of the rotational ability of specific crystals, the possibility of evaluating the structural perfection of the studied crystals.

Currently, there is a rapid development of thermophysics of solids associated with the need of creating models with a high degree of predictive reliability. This paper presents new approaches to solving relevant issues related to the study of heat transfer in semiconductors and dielectrics, mainly concerning nano-structures. The first of the considered tasks is the creation of a statistical model of the processes of interaction of heat carriers – phonons – with rough surfaces of solids. For the first time authors proposed a method based on the statistics of the slopes of the profile of a random surface. The calculation results are the mean free paths of phonon between the opposite boundaries of the sample, which are necessary for calculating the effective thermal conductivity in ballistic and diffusion-ballistic regime of heat transfer, depending on the roughness parameters. The second task is to develop methods for calculating the processes of heat transfer through the contact surfaces of solids. We were able to show that, taking into account the phonon dispersion and the corresponding restrictions on the frequency values, the modified acoustic mismatch model for calculating Kapitsa resistances can be extended to temperatures above 300 K. Previously, the limit of applicability of this method was considered to be a temperature of 30 K. Moreover, the proposed method is also generalized to the case of rough interfaces. The third task is a new approach to determining the thermal conductivity of solids. The authors have developed a method of direct Monte Carlo simulation of phonon kinetics with strict consideration of their interaction due to the direct use of the laws of conservation of energy and quasi-momentum. The calculations of the thermal conductivity coefficient for pure silicon in the temperature range from 100 to 300 K showed good agreement with the experiment and ab initio calculations of other authors, and also allowed us to consider in detail the kinetics of phonons.

The work is devoted to the study of the process of changing the polarization of hafnium oxide crystals in the orthorhombic phase associated with the gradual weakening of the polarization effects in FeRAM elements based on thin films of hafnium oxide HfO₂. To solve the problem, quantum-mechanical calculations of the structure of orthorhombic hafnium oxide were carried out, a possible way of crystal rearrangement during a change in polarization upon application of voltage was identified, and its optimization was carried out using the elastic band method. The values of the polarization change and the energy barrier of the corresponding transition are obtained. A study of the stability of this transition has been carried out. The results of a series of computational experiments using high-performance computing systems of hybrid architecture based on the Center for Collective Use of the FRC IU RAS are presented. An analysis of the results shows that, despite the low energy barrier of the transition, the probability of a spontaneous change in polarization is low due to the impossibility of changing the polarization of an individual cell without taking into account the influence of the polarizations of neighboring cells.

The effect on the electrical parameters of the SiON/AlGaN/GaN structures of treatment of different durations of low-energy nitrogen plasma was studied. The AlGaN surface was subjected to plasma treatment in the working chamber of the plasma-chemical deposition unit before starting the monosilane to form the SiON film. Changes in the transport properties (conductivity and mobility) of the canal and capacitive properties of the structures were evaluated. It has been experimentally shown that such treatment leads to a change in the magnitude of polarization charges both at the insulator-AlGaN interface and at the AlGaN/GaN interface. With the help of C–V measurements-in the hysteresis mode, it is shown that at the control voltage U > +4 — +5 V ), some of the channel electrons are captured at deep centers at the SiON-AlGaN interface, and with an increase in the duration of exposure to plasma time, a sharp increase is observed charge Q_it, formed by electronic boundary states. The use of additional treatment with nitrogen plasma transfers work for nitride structures from the D-mode (V_th = –4 V) to the E-mode (V_th = +0.9 V).
Using Auger-measurements, it was shown that plasma treatment leads to a change in the amount of oxygen in the SiON layer and in nano-regions of the barrier layer, and with an increase in the duration of plasma exposure, a sharp decrease in the amount of oxygen in these layers is observed. Also, when using plasma treatment, the redistribution of Ga and Al at the AlGaN–GaN interface i.e. in the channel area. Using Auger measurements near the SiON–AlGaN interface from the side of the insulator, the localization of nitrogen atoms chemically bonded with silicon N(Si) with the formation of a peak at the interface, the size of which increases with increasing duration of plasma exposure.

The physicochemical foundations of the basic structures and technologies for the production of promising electrolytic cells for the accumulation of electrical energy with a specific energy intensity for reusable cells of 350–500 W  ⋅ h/kg at the first stage and 1000 W  ⋅ h/kg at the second stage have been developed. Along with traditional chemical current sources and ionistors, supercapacitive capacitor structures with a thin dielectric in a double electric layer and hybrid capacitors appear, in which energy is accumulated both in a double electric layer and due to electrochemical processes. This approach makes it possible to reduce the internal resistance of electrolytic cells, which leads to a decrease in heat generation during operation and, accordingly, an increase in specific energy consumption, operational safety, a decrease in charging time, and an increase in specific power. 
A promising anode is a nanostructured electrode material, which is a carbon-based matrix filled with a nanostructured reactive material. Promising materials for filling the carbon matrix are Li and its alloys, Si, Al, Na, Sn, Mg, Zn, Ni, Co, Ag, and a number of other materials and their compounds. The influence of the specific area of the carbon material, dielectric constant, addition of a chemically active substance on the specific energy consumption has been studied. The theoretical values of the specific energy capacity of hybrid capacitors with a metal-air system are calculated. A thin-film technological complex has been developed that ensures the creation of a new generation of electrode materials, the design of which is a carbon matrix with a highly developed surface, in which there is a tunnel-thin dielectric, on the surface of which a chemically active material is placed.

The In₂O₃ : Er films were deposited on Si substrates by the RF magnetron sputtering technique. For the Si substrates of both n- and p-type the current through the MOS-structure (Si/In₂O₃ : Er/In-contact) was described by the thermionic emission of the main currents over the barrier, with the correction of the applied voltage into the partial voltage drop in silicon. By the temperature dependence measurements of the forward currents at small under-barrier biases the barriers for the current injection from Si into the films were found equal to the 0.14 eV and 0.3 eV for the electrons and holes accordingly. The obtained small barrier for the holes is described by the presence of the defect state density. It tails from the valence band maximum into the In₂O₃ : Er band gap and provides there the conduction channel for holes. The defect state density in the In₂O₃ : Er band gap is proved by the PL data in the respective energy range 1.55–3 eV. The band analysis for the hetero-structure Si/In₂O₃ : Er is performed. It gives the energy gap between the electrons in the In₂O₃ : Er conduction band and the holes in the band gap channel equal to the 1.56 eV.

At the Prometheus medical accelerator with a proton beam energy of 225 MeV, a source of fast and epithermal neutrons was constructed and measurements of neutron dose profiles at the output of the neutron channel were carried out using the BDMN-100 detector. A heavy NaI target was used to produce fast neutrons. Together with the research laboratory of the Central Laboratory of Avangard JSC, a new protective material against neutrons called wikineutron was developed, with a different percentage of ¹⁰B. This new material has been studied many times at the Prometheus proton accelerator and the Pakhra electron accelerator. Based on the developed new protective materials against neutrons, a shadow protection was formed, made in the form of surface contacting cones, forming a channel of fast and epithermal neutrons. Fast neutrons can be used for remote therapy. Also, a neutron beam can be used to study biological objects and cells. It is also possible to use a neutron source from the Prometheus accelerator for the treatment of superficial tumors. The developed neutron channel can be used for medical work on the creation of new radiopharmaceuticals containing boron and other highly absorbing elements. The developed neutron source is a compact low-power source of therapeutic neutrons, which can be used for the treatment of superficial types of cancer. The main goal of the work was: the formation, based on the developed neutron-absorbing materials, of a neutron channel, which has a simple design and can be used for boron-neutron capture therapy and nadepithermal therapy; creation on the neutron channel of a beam of epithermal neutrons and supra-epithermal neutrons to assess the effectiveness of the use of radiopharmaceuticals.
The developed neutron-absorbing materials made it possible to create a neutron channel of epithermal neutrons and supra-epithermal neutrons for therapy and the development of gold-based radiosensitizers.

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