For the first time, a detailed comprehensive study of the "dry" etching of dislocation and dislocation-free germanium samples on the {111}, {110} and {100} planes has been carried out. Etching was carried out by exposure to pulses of nanosecond UV laser radiation of subthreshold intensity (wavelength 355 nm, duration ~ 10 ns, energy density ~ 0.5–1.3 J/cm², pulse repetition rate 100 Hz, divergence 1–2 mrad). Before and after laser heat treatment of the surface, the samples were examined using a Zygo optical profilometer and a scanning electron microscope. Features of the nature of damage to surfaces corresponding to different crystallographic planes of single crystals of industrial dislocation germanium are revealed. They are compared with data on subthreshold damages of typical dislocation-free crystals.

It is shown that in dislocation samples of germanium on the {111} plane, it is possible to create a regime of exposure to radiation, leading to the formation of etch pits that are outwardly identical to dislocation pits detected during selective chemical etching. Their concentration corresponds in order of magnitude to the density of dislocations.

On the {100} plane of dislocation samples, etching results were also found, which clearly have a crystallographic nature. At an energy density of the acting radiation ≥ 0.4 J/cm², on the surfaces of dislocation ({100} plane) and dislocation-free germanium ({111}, {100}, {110} planes), only individual spots ~ 50 μm in size were registered, as well as individual microcraters ~ 0.1–1 μm in size, which do not have crystallographic features. The possibility of environmentally friendly detection of dislocations in germanium without the use of chemical reagents is shown.

Mechanical processing of semiconductor monocrystalline ingots is one of the key stages in the production of GaAs wafers. The main issue for obtaining high-quality plates is to determine the optimal parameters of machining and is to identify the dependencies of the surface quality of the substrates after cutting on the parameters set in this technological process. Technology for the production of polished semiconductor wafers (substrates) almost all semiconductor materials have a similar and has in its difference only a number of distinctive features related to the mechanical and structural features of individual materials. Mechanical processing is the first stage after crystal growth, in which it is necessary to observe and improve many technological parameters to obtain high-quality finished products. In the technological process of semiconductor processing, it is necessary first of all to divide the crystal into plates with similar surface characteristics. The quality of this separation determines which plates will eventually turn out and how suitable they will be as substrates for the production of devices in mass production. The study of the influence of cutting parameters on the structure of the disturbed layer and the basic geometric parameters of the plates allows us to identify the optimal parameters of mechanical cutting and to identify the range of deviations possible to obtain plates of similar quality for further processing.

FeCoCu ternary nanoparticles distributed and stabilized in the carbon matrix of FeCoCu/C metal-carbon nanocomposites have been synthesized using controlled IR pyrolysis of precursors consisting of the “polymer / iron acetylacetate / cobalt and copper acetates” type system obtained by joint dissolution of components followed by solvent removal. The effect of the synthesis temperature on the structure, composition and electromagnetic properties of the nanocomposites has been studied. By XRD was shown that the formation of the FeCoCu ternary nanoparticles occurs due to the interaction of Fe₃С with the nanoparticles of the CoCu solid solution. An increase in the synthesis temperature leads to an increase in the size of the metal nanoparticles due to their agglomeration and coalescence as a result of matrix reconstruction. Furthermore, ternary alloy nanoparticles having 
a variable composition may form depending on the synthesis temperature and the content ratio of the metals. Raman spectroscopy has shown that the crystallinity of the carbon matrix of the nanocomposites increases with the synthesis temperature. The frequency responses of the relative permittivity and permeability of the nanocomposites have been studied at 3–13 GHz. It has been shown that a change in the content ratio of the metals noticeably increases both the dielectric and the magnetic losses. The former loss is caused by the formation of a complex nanostructure of the nanocomposite carbon matrix while the latter one originates from an increase in the size of the nanoparticles and a shift of the natural ferromagnetic resonance frequency to the low-frequency region. The reflection loss has been calculated using a standard method from the experimental data on the frequency responses of the relative permittivity and permeability. It has been shown that the frequency range and the absorption of electromagnetic waves (from –20 to –52 dB) can be controlled by varying the content ratio of the metals in the precursor. The nanocomposites obtained as a result of the experiment deliver better results in comparison with FeCo/C nanocomposites synthesized under similar conditions.

The paper studies the thermal, electrical and thermoelectric properties of ZnO–Me_xO_y ceramics with 1 ≤ x, y ≤ 3, where Me = Al, Co, Fe, Ni, Ti. The samples were made on the basis of ceramic sintering technology of powder mixtures of two or more oxides in an open atmosphere with variations in temperature and duration of annealing. Structural and phase studies of ceramics indicate that the addition of powders of Me_xO_y alloying agents to ZnO powder with a wurtzite structure after the synthesis process leads to the release of secondary phases such as Zn_x(Me)_yO4 spinels and a 4-fold increase in the porosity of the resulting ceramics. Studies of thermal conductivity at room temperature indicate the predominance of the lattice contribution. The decrease in thermal conductivity during doping is due to an increase in phonon scattering due to the influence of the following factors: (1) the size factor when replacing zinc ions in the ZnO (wurtzite) crystal lattice with metal ions from the added Me_xO_y oxides; (2) the formation of defects – point, grain boundaries (microstructure grinding); (3) increase in porosity (decrease in density); and (4) formation of additional phase particles (such as spinels Zn_x(Mе)_yO₄). The effect of these factors in the substitution of zinc ions with metals (Co, Al, Ti, Ni, Fe) leads to an increase in the thermoelectric Q-factor of ZT by 4 orders of magnitude (due to a decrease in electrical resistivity and thermal conductivity with a relatively small decrease in the coefficient of thermal EMF). The reason for the decrease in electrical resistance is the more uniform redistribution of alloying metal ions in the wurtzite lattice, resulting in an increase in the number of donor centers, formed with an increase in the duration of annealing.

Ga₂O₃ is an ultra-wideband material with excellent optical characteristics. It is a promising material for power applications and optoelectronics because of its high electrical breakdown voltage and radiation hardness. It is optically transparent for visible light and UVA but UVC-sensitive. One of the main disadvantages of this material is the anomalous slow photoeffect: photoconductivity rise and decay characteristic times can be more than hundreds of seconds long. This "slow" photoconductivity effect severely limits the utilisation of the Ga₂O₃-based devices. The aim of this work is the investigation of the nature of this effect. The results of the photoinduced current rise and decay under 530 nm and 259 nm LED are measured in the HVPE-grown α-Ga2O3-based Schottky diode. Upon UV-illumination the photocurrent rise consists of three parallel processes: fast signal growth, slow growth and very slow decay with characteristic times near 70 ms, 40 s and 300 s respectively. Subsequent 530 nm LED illumination resulted in photoinduced current rise consisting of two mechanisms with characterisatic times 130 ms and 40 s on which a very slow decrease of the photocurrent amplitude with characteristic time of 1500 s was superimposed. 530 nm illumination stimulates this process. Protoinduced current relaxation analysis shows the presence of the deep levels with energies (E_C - 0.17 eV). It is suggested that extremely slow relaxations can be associated with potential fluctuations near the Schottky barrier.

The influence of aluminum oxide films obtained by high-frequency cathode sputtering of an Al₂O₃ target in argon atmosphere on charging properties of the SiO₂/p-Si interface was investigated. High-frequency C-V characteristics for MIS-structure with one-layer dielectric films: SiO₂ (0,10 µm and 0,36 µm), Al₂O₃ (0,14 µm) – and its double-layers compositions were measured. Experiment was carried out with a KDB-4.5 and a KDB-5000 substrates. Some electrophysical parameters of the obtained films such as U_FB and Q_ss were calculated. Based on experimental results it was confirmed that the embedded negative charge of Al₂O₃ film prevented the formation of the inversive layer on p-Si surface by compensation of the embedded positive charge of SiO₂ film and enhancement of semiconductor surface with majority charge carriers and, thus, allowed stabilization of charge properties of the SiO₂/p-Si interface. The applicability of Al₂O₃ film as additional dielectric covering for manufacture technology of photodiodes on high-resistance p-Si was confirmed by applying on a multi-element p-i-n photosensitive element (PE) as an example. It was established that passivation of silicon dioxide on periphery and between the elements of PE by Al₂O₃ film improved I-V characteristics and insulation resistance, which lead to increased yield rate of photodiodes.

Сrystal structure, piezoelectric and magnetic properties of solid solutions BiMn_1-xFe_xO₃ (x ≤ 0.4) prepared by solid-phase reactions from a stoichiometric mixture of simple oxides at high pressures and temperatures have been studied. The structure of the compounds is characterized by the concentration driven phase transition from the monoclinic structure to the orthorhombic structure at x ≈ 0.2; wherein the ordering d_z2 of the orbitals of Mn³⁺ ions is destroyed, and the inhomogeneous magnetic state is stabilized. Solid solutions with 0.2 ≤ x ≤ 0.4 are characterized by a nonzero piezoelectric response, wherein both ferroelectric and magnetic domain structures exist, the ferroelectric switching voltage decreases with an increase of iron ions concentration, while the residual magnetization value decreases. The maximum value of the piezoresponse signal is observed in the compound BiMn_0.7Fe_0.3O₃. The work clarifies the relationship between the chemical composition, the crystal structure, piezoelectric and magnetic properties of solid solutions BiMn_1-xFe_xO₃. The presence of both magnetic and electric dipole ordering indicates the perspectives for the practical usage of such materials. 

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