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High-voltage (2000V) 4H-SiC Schottky diodes are fabricated. To suppress the premature breakdown at the edge of diode structures, a field plate is formed as the edge termination. In this plate, an insulator layer is formed via the self-aligned implantation of high-energy (53 MeV) argon ions into 4H-SiC. To mask the active region of the diodes, 10–12-μm-thick nickel columns with vertical walls are grown on Schottky contacts by local electrochemical deposition. A comparison of the current–voltage characteristics of terminated and nonterminated diodes shows that the forward current–voltage characteristics barely degrade after implantation, whereas the reverse current–voltage characteristics are greatly improved. Both the forward and reverse current–voltage characteristics of terminated diodes are well described in terms of the classical thermionic emission model if lowering of the Schottky-barrier height with increasing bending of energy bands is taken into account.

The TCAD simulation of high-voltage 4H-SiC-based p+–n–n+ diodes with an edge semi-insulating i-type region created via the complete compensation for doping donors in the n region by deep carrier traps (the energy position of the traps in the 4H-SiC band gap is 1.2 eV below the bottom of the conduction band) is performed. It is shown that the efficiency of the edge semi-insulating i-type region at room temperature is close to 100%: the avalanche breakdown voltage of the p+–n–n+ diode with the edge i region is 1100 V, a value equal to the breakdown voltage of an idealized diode with a one-dimensional p+–n–n+ structure. The efficiency of the i-type region as the edge region gradually deteriorates with an increase in temperature above 600 K due to the thermal emission of electrons captured at the traps. The results obtained are briefly discussed in view of the practical application of radiation technology for the formation of edge semi-insulating i regions in 4H-SiC devices.

We consider problems associated with the reliability of high-power 4H-SiC Schottky diodes (SDs) during short-term electric overloads in the reverse direction (for diodes operating in the pulsed avalanche regime). In particular, we analyze the effect of nonuniformity of an avalanche breakdown over the diode area on the maximal avalanche energy (MAE) that can be dissipated by the diode prior to its secondary thermal breakdown. For estimating the uniformity of an avalanche breakdown, we propose that the measured pulse reverse current–voltage (I–V) characteristic of the diode be compared with the calculated I–V characteristic of an ideal quasi-one-dimensional diode. We measured reverse I–V characteristics of commercial 4H-SiC SDs: single avalanche current pulses with a duration of ~1 μs were passed through the diodes; during measurements, the pulse amplitudes grew to values for which a catastrophic failure of diodes occurred. It is shown that an increase in the differential resistance of diodes on the avalanche segment of the I–V curve and a decrease in the extrapolated breakdown voltage (as compared to values calculated for ideal diodes) can lead to a decrease in the MAE.

We have demonstrated that SiC mesastructures with gently sloping sidewalls form with the help of selective reactive ion etching (RIE) of silicon carbide through a photoresist mask (slanted walls are formed during simultaneous etching of SiC and the resistive mask with the edge in the shape of a sharp wedge). A simple geometrical model of etching predicts that the resultant slope of the mesastructure wall must be specified by two parameters, i.e., initial angle of the resistive wedge and the selectivity of SiC etching relative to the photoresist (ratio of etching rates of SiC and photoresist). For experiments, we used polished 4H–SiC wafers with the (0001) orientation. Photoresist regions with an edge angle of 22° were deposited using photolithography onto the Si side of the wafers. Then etching of mesastructures was performed in nitrogen trifluoride in a setup with an inductively coupled plasma. We selected RIE parameters ensuring SiC and photoresist etching with rates of 55 and 160 nm/min, respectively (etching selectivity was 1 : 3). The SiC mesastructures formed by etching have a height of 3.2 μm and gently sloping sidewalls with a slope of about 8°. This technology can be used for preparing high-voltage SiC devices with a straight bevel.

The prospects for the protection of high-voltage 4H-SiC-devices from edge breakdown via the formation of mesa structures with inclined walls (negative beveling) are considered. Numerical simulation of the spatial electric-field distribution in high-voltage (~1500V) reverse-biased mesa-epitaxial p+–p–n0–n+ 4H-SiC diodes is performed. It is shown that negative beveling with small angles of less than 10° from the plane of the p–n0 junction makes it possible to reduce severalfold the surface edge electric field as compared to that in the bulk. A combined protection method is suggested as the edge-termination technique for 4H-SiC diodes with a p+–n0–n+ structure, Schottky diodes with an n0 blocking base, and bipolar n+–p–n0 transistors via the implantation of boron along with negative beveling. The possibility of fabricating mesa structures with inclined walls via the photolithography and dry etching of silicon carbide is briefly discussed.

Methods of micro-profiling of 4H-SiC are described: formation of mesa structures with inclined walls (off-vertical wall inclination angle exceeding 45°) by reactive ion etching; etching of mesa structures with a flat bottom and inclined walls (off-vertical wall inclination angle being smaller than 45°) by ion-beam and reactive ion plasma etching. The application of etching methods in the fabrication technology of 4H-SiC-based mesa-epitaxial field-effect transistors with a Schottky gate is demonstrated.

The paper reports new geochronological, petrological, and isotope-geochemical data on the syenites and alkali syenites of the Artyushki massif, and the monzonites of the Gusikha massif. These massifs are located along the southwestern and northeastern margins of the Pachelma aulacogen, in the southeastern part of the East European Platform (EEP). They have Early Cambrian ages of 524 ± 3 (Artyushki) and 514 ± 2 Ma (Gusikha) obtained by the U-Pb zircon method and similar ages of amphibole and K-feldspar by the 40Ar/39Ar method. This time period has previously been regarded as amagmatic in the EEP evolution. The Artyushki massif is made up of Amp-Cpx syenite porphyries and Grt-Cpx alkali syenite porphyries and their fenitized varieties. As compared to the Amp-Cpx varieties the Grt-Cpx rocks are more peralkaline (A/NK > 0.9) and have higher LREE and HFSE, and fractionated HREE patterns. The metasomatized (fenitized) varieties are more potassic and bear geochemical evidence of fluid reworking (high Y/Ho ratios, significant Zn variations, and etc.). Bulk samples have weakly radiogenic Sr isotopic compositions: (87Sr/86Sr)520 are within 0.703066–0.703615. The values of εNd(520) vary from –0.69 to +1.64. The Grt-Cpx syenite porphyries have the positive εNd(520), while the Amp-Cpx and fenitized syenite porphyries feature negative εNd. The Gusikha massif consists of biotite-amphibole and biotite monzonites. Similar to the Artyushki syenites in SiO2 contents, the Gusikha monzonites have higher Mg# (0.22–0.54 and 0.34–0.71 for the Artyushki and Gusikha massifs, respectively). They are also characterized by a negative Nb-Ta anomaly (Nb/Nb* = 0.5), high Ва/Sr ratio, and highly radiogenic (87Sr/86Sr)520 = 0.705204 and 0.705320. Their Nd-isotopic compositions correspond to εNd(520) = –6.7 and –7.0. Two melts contributed to the formation of the Artyushki massif. One was a strongly contaminated melt (Amp-Cpx syenite porphyries, the other was weakly contaminated (Grt-Cpx syenite porphyries). The main contribution was phonolitic melt derived from the melting of a moderately metasomatized (carbonate- and amphibole-bearing) shallow lithospheric mantle. The earliest and deepest melt portions were carbonate-silicate in composition. The geochemical, as well as the Sr and Nd isotopic compositions of the Gusikha monzonites indicate a predominant crustal contribution and pervasive reworking of the lithospheric mantle beneath southeastern Volgo-Uralia of the EEP in the Mesoproterozoic. Both massifs feature the geochemistry of within-plate and supra-subduction derivatives, which suggests a postorogenic tectonic setting of the magmatism. The presence of the Early Cambrian postorogenic magmatism within the East European Platform/Baltica is direct evidence for the involvement of Baltica in the collisional and/or accretionary events during the terminal Neoproterozoic – the beginning of the Paleozoic. This suggests reworking of the lithospheric mantle of Baltica during its collision with Timanian and East Avalonian/Cadomian terranes, including Scythia.

Voltage control of ferromagnetism on the nanometer scale is highly appealing for the development of novel electronic devices with low power consumption, high operation speed, reliable reversibility and compatibility with semiconductor technology. Hybrid structures based on the assembly of ferromagnetic and semiconducting building blocks are expected to show magnetic order as a ferromagnet and to be electrically tunable as a semiconductor. Here, we demonstrate the electrical control of the exchange coupling in a hybrid consisting of a ferromagnetic Co layer and a semiconductor CdTe quantum well, separated by a thin non-magnetic (Cd,Mg)Te barrier. The electric field controls the phononic ac Stark effect—the indirect exchange mechanism that is mediated by elliptically polarized phonons emitted from the ferromagnet. The effective magnetic field of the exchange interaction reaches up to 2.5 Tesla and can be turned on and off by application of 1V bias across the heterostructure., Manipulating magnetic orders by electric fields promises energy efficient spintronic applications. Here the authors demonstrate electrical control of s-p exchange interaction in a ferromagnet-semiconductor quantum well structure due to the phononic ac Stark effect.

The article describes the main results of the study investigating the predictors of the behavioral strategy choice among Russians in an imaginary conflict with a representative of the North Caucasus ethnic groups. The theoretical and methodological basis of the research includes the dual concern model, the refined theory of personal values by S. Schwartz and the concept of intergroup anxiety by W. Stefan and C. Stefan. As the predictors of the behavioral strategy choice in a conflict, following personal values were considered: Openness to change, Conservation, Self-Transcendence and Self-Enhancement. The role of intergroup anxiety was tested as a moderator affecting the link between values and behavior in the conflict. Cultural identity and self-esteem were considered as control variables. The study involved 214 ethnic Russians living in Russia (73 men, 141 women, age M = 31.96, SD = 10.21). Respondents were involved in the study helping by “snowball” method. The following methods were used: Organizational Conflict Inventory by M. Rahim in the modification of J. Oetzel, PVQ-R by S. Schwartz, the intercultural communication apprehension scale by J. Neulep and D. McKrosky, and the certain scales from the MIRIPS questionnaire. The results of the path analysis showed that the choice of the competing is positively related to the values of Self-Enhancement and is negative with the values of Self-Transcendence. The choice of collaborating strategy has a positive relation with the values of Self-Transcendence and Openness to change. The choice of an avoiding strategy is positively related to the values of Conservation and intergroup anxiety. The choice of the accommodating did not reveal a significant influence of values but this strategy is in positive connection with cultural identity and in a negative connection with self-esteem. Intergroup anxiety is a moderator of the relationship between the value of Openness to change and the collaborating strategy. The obtained results can be used in the development of recommendations in the field of intercultural communication and in the settlement of intercultural conflicts.

The high-voltage p+–p0–i–n0–n+ structures based on epitaxial gradual GaAs p0–i–n0 junction grown in hydrogen or argon atmosphere have been studied by capacitance-voltage spectroscopy and deep-level transient spectroscopy, DLTS, before and after neutron irradiation. After neutron irradiation, the broad bands associated with electron emission from the states lying above midgap appear in DLTS spectra of both p0–i–n0 GaAs structures. It is assumed that the carrier emission mechanism in the neutron-irradiated GaAs is the same as that in amorphous materials.

To provide new insights into the origin of megacrysts and metasomatism of the subcontinental lithospheric mantle (SCLM), we present a detailed petrographic and geochemical investigation of clinopyroxene-phlogopite xenoliths and clinopyroxene megacrysts from the Grib kimberlite (Arkhangelsk diamond province, Russia). Clinopyroxene megacrysts and clinopyroxene from clinopyroxene-phlogopite xenoliths have similar petrography, major and trace element compositions, and are therefore classified as Cr-rich megacrysts. Geothermobarometry suggests that Cr-rich clinopyroxenes originate from within the SCLM (3.6–4.7 GPa and 764–922 °C). Phlogopite from clinopyroxene-phlogopite xenoliths have low-Ti and -Cr compositions that overlaps with phlogopite megacrysts from the Grib kimberlite. The clinopyroxene-phlogopite rocks within the SCLM are the main source for Cr-rich clinopyroxene and low-Ti phlogopite megacrysts in the Grib kimberlite matrix. Trace element compositions of studied Cr-rich clinopyroxenes have similar geochemical features to clinopyroxenes megacrysts occurrences worldwide and overlap with clinopyroxenes from phlogopite-garnet peridotite xenoliths from the Grib kimberlite. The strong depletion in Ti, Nb, Ta and to a lesser extent in Zr and Hf in clinopyroxene reflects equilibrium with Ti-oxides, such as ilmenite. The clinopyroxene-phlogopite xenoliths could be the final product of metasomatism of garnet peridotites within the SCLM beneath the Grib kimberlite. The calculated equilibrium of clinopyroxene melt compositions suggests that the metasomatic agents were derived from silicate-bearing kimberlite melts. The presence of veinlets infilled with kimberlitic mineral assemblages in clinopyroxene grains suggests that the clinopyroxene-phlogopite rocks experienced intense interactions with kimberlite melt after their formation, but before their entrainment into the host kimberlite magma. This interaction resulted in the formation of high-Ti and -Cr phlogopite and high-Ti clinopyroxene rims, zones and grains with spongy textures. Finally, we propose the sequence of metasomatic events that occurred in the SCLM and the subsequent formation of the Grib kimberlite.

The results of a study of multilayer photodiodes based on InAs1- x Sb x solid solutions (0.3 < x λ 0.1 ≈ 11 μm at room temperature are presented. The current-voltage and spectral characteristics of photosensitivity and electroluminescence were analyzed in the temperature range of 80 ÷ 300 K. Experimental samples of photodetectors are characterized by a quantum efficiency of 0.23 at 150 K and a diffusion mechanism of current flow at least in the 200-300 K range. The detectivity of the immersion lens PD at the maximum has values of at least D*8 µm = 8·108 and D* 5.5 µm = 1010 cm·Hz1/2W-1 at 300 and 150 K, respectively.

Narrow gap heterostructures consisting of two double heterostructures (N-InAsSbP/n-InAs/P-InAsSbP and P-InAsSbP/n-InAs0.9Sb0.1/N-InAsSbP) grown sequentially onto a n+-InAs substrate and further processed into a two-color photodiode with individual sensing operation at 3.3 and 4 have been studied. Presented and discussed are the photodiode construction details, I-V characteristics as well as sensitivity and detectivity spectra measured at room temperature.

The results of a study of multilayer p-n heterostructures based on InAsSbx solid solution (0.3 ˂ x ˂0.35), with a long-wavelength photosensitivity boundary of λ0.1 ≈ 9.5 μm at room temperature are presented. The current-voltage and spectral characteristics of photosensitivity and electroluminescence were analyzed in the temperature range 80 ÷ 300 K. It is shown that the photoelectric properties are determined by the diffusion mechanism of current flow, and experimental samples of photodetectors are characterized by a quantum efficiency of Si ⩾ 1 A / W.

The paper reports detailed data on phlogopite from kimberlite of three facies types in the Arkhangelsk Diamondiferous Province (ADP): (i) massive magmatic kimberlite (Ermakovskaya-7 Pipe), (ii) transitional type between massive volcaniclastic and magmatic kimberlite (Grib Pipe), and (iii) volcanic kimberlite (Karpinskii-1 and Karpinskii-2 pipes). Kimberlite from the Ermakovskaya-7 Pipe contains only groundmass phlogopite. Kimberlite from the Grib Pipe contains a number of phlogopite populations: megacrysts, macrocrysts, matrix phlogopite, and this mineral in xenoliths. Phlogopite macrocrysts and matrix phlogopite define a single compositional trend reflecting the evolution of the kimberlite melt. The composition points of phlogopite from the xenoliths lie on a single crystallization trend, i.e., the mineral also crystallized from kimberlite melt, which likely actively metasomatized the host rocks from which the xenoliths were captured. Phlogopite from volcaniclastic kimberlite from the Karpinskii-1 and Karpinskii-2 pipes does not show either any clearly distinct petrographic setting or compositional differentiation. The kimberlite was dated by the Rb–Sr technique on phlogopite and additionally by the 40Ar/39Ar method. Because it is highly probable that phlogopite from all pipes crystallized from kimberlite melt, the crystallization age of the kimberlite can be defined as 376 ± 3 Ma for the Grib Pipe, 380 ± 2 Ma for the Karpinskii-1 pipe, 375 ± 2 Ma for the Karpinskii-2 Pipe, and 377 ± 0.4 Ma for the Ermakovskaya-7 Pipe. The age of the pipes coincides within the error and suggests that the melts of the pipes were emplaced almost simultaneously. Our geochronologic data on kimberlite emplacement in ADP lie within the range of 380 ± 2 to 375 ± Ma and coincide with most age values for Devonian alkaline–ultramafic complexes in the Kola Province: 379 ± 5 Ma; Arzamastsev and Wu, 2014). These data indicate that the kimberlite was formed during the early evolution of the Kola Province, when alkaline–ultramafic complexes (including those with carbonatite) were emplaced.

Optical extinction in a metal–semiconductor metamaterial based on a AlGaAs matrix, which contains random arrays of AsSb plasmon nanoinclusions, is studied. The metamaterial is grown by molecular beam epitaxy at a low temperature. A system of nanoinclusions of various sizes is formed by annealing at temperatures 400, 500, and 600°C. Investigation of the sample’s microstructure by transmission electron microscopy shows that the average size of nanoinclusions at the used annealing temperatures is 4–7, 5–8, and 6–9 nm, respectively. It is shown experimentally that AsSb nanoparticle arrays in the AlGaAs matrix cause the resonant absorption of light. It is established that the plasmon-resonance parameters found in the metamaterial are almost independent of the sizes of the AsSb nanoinclusions. The plasmon-resonance energy is (1.47 ± 0.01) eV, while its full width at half maximum is (0.19 ± 0.01) eV.

We present the results of optimization of the design and molecular beam epitaxy (MBE) growth technology of N-AlGaAs:Si/n +-GaAs:Si/p +-GaAs:Be/P-AlGaAs:Be heterostructures for tunnel diodes (TDs). The achieved maximum peak current density level (J p = 513 A/cm2) allows these TDs to be used for cascade connections both in multijunction solar cells and in structures of tunnel-coupled laser diodes. The initial region of the J–U curve of TDs exhibits nonlinearity that is explained by a residual potential barrier left in the p +–P–p + isotype heterojunction (confining the active region of TD) as a result of non-optimum doping of Al0.4Ga0.6As alloy.

The optical absorption in a metal-semiconductor metamaterial based on the AlGaAs matrix has been investigated. The key feature of this material is the presence of random arrays of metallic AsSb nanoinclusions modifying its dielectric properties. It has been shown that the presence of such arrays in the material leads to resonance absorption of light by surface plasmons in AsSb nanoinclusions in the incident photon energy range from 1.37 to 1.77 eV. The experimental spectrum of the extinction coefficient at an energy of 1.48 eV exhibits a resonance peak with the half-width equal to 0.18 eV. The extinction coefficient for AsSb nanoinclusions in the AlGaAs matrix has been calculated in terms of the Mie theory. The calculated spectrum of the extinction coefficient also includes a resonance peak with the energy and half-width equal to 1.48 and 0.18 eV, respectively. The calculated plasma energy for free-standing nanoinclusions in vacuum is 7.38 eV.

A correlation between the main parameter of a solar cell, the conversion efficiency, and its dark I–V characteristic is investigated. A formula is derived that expresses an increment (decrement) of the efficiency through a decrement (increment) of the current measured at a certain voltage (here at 2.4 V). Relationships are deduced based on which six methods for passivating the sidewalls of triple-junction InGaP/GaAs/Ge heterostructures grown by metal-organic vapor-phase epitaxy are tested to see how they influence the dark I–V characteristic. The influence of different factors, such as post-growth annealing, damaging radiation, etc., on the solar cell efficiency can be estimated by taking the dark I–V characteristic.

In this paper, we report on the initial studies of connecting elements for cascade photodetectors. The heterostructures used in this work are based on InP. As a connecting element, it is proposed to use nanocrystalline inclusions instead of the tunnel junction. GaP nanocrystals are most suitable for this purpose because this material does not cause absorption of the incident radiation.

A computational model is developed for the evaluation of the kinetics of wear and durability of plain bearings taking into account the presence of small out-of-roundness of the contours of their components operating in contact. By using the developed cumulative model, we study the schemes of plain bearings with different lobing of the shaft and the bush. It is shown that the degree of wear of the bush of a bearing increases in the case of lobing of one or both elements. At the same time, the degree of the wear of the shaft decreases. More complex types of lobing of the contours clearly lead to strong changes in the degree of wear.

Characteristics of GaAs photodiodes have been studied before and after the chemical nitridation of their surface in hydrazine sulfide solutions, which leads to substitution of surface As atoms with N atoms to give a GaN monolayer. The resulting nitride coatings hinder the oxidation of GaAs in air and provide a decrease in the density of surface states involved in recombination processes. The device characteristics improved by nitridation are preserved during a long time.

The possibility of improving the dynamic characteristics of turn-off switching of high-voltage power GaAs p-i-n diode by applying a heteroepitaxial AlGaAs emitter is investigated in this work. Using a wideband AlGaAs n+-emitter in manufacturing of power GaAs p-i-n diodes allows to vary the coefficient K value which characterizes the recovery softness of diode blocking properties when switching off in the range of 0.1 to 2 or more. The diodes with blocking voltage of up to 700 V, the reverse recovery time of about 40 ns and K > 1 were manufactured.

Forward dark and load I - V characteristics of triple-junction GaInP/Ga(In)As/Ge solar cells (SCs) in the temperature range 300 - 80 K have been studied. At temperatures below 200 K, jumps of current and voltage in, respectively, dark and load characteristics were observed experimentally and attributed to the existence of a counter potential barrier formed by isotype heterolayers between the tunnel diode and the Ge p-n junction in the InGaP/Ga(In)As/Ge SC. An analysis of the forward dark characteristics of GaInP/Ga(In)As/Ge SCs, recorded at 80 K, enabled evaluation of the potential and real conversion efficiencies of incident sunlight. The influence exerted by the shape of the side mesa surface of GaInP/Ga(In)As/Ge SCs on the dominant current flow mechanisms was analysed. A method for single-step separate etching was suggested and studied. This method allows one to reduce surface leakage currents and raise the yield of suitable SCs with an efficiency greater than 35% at low sunlight concentrations (C = 10 - 100, T = 300 K). The suggested post-growth technology reduces the number of fabrication operations and the SC production cost and improves the reliability of the SC operation in a wide temperature range.

The following conclusions can be drawn from analysis of the results on the enlarged experimental installation at the Novokuibyshevsk Refinery.

1. Industrial tests on the continuous method of paraffin oxidation carried out in the “Twelfth Meeting of the Communist Party USSR” Ufa Oil Refinery have shown that the output of the columns can be doubled without deterioration of the product quality owing to change-over to the new hydrodynamic regime. 2. The continuous oxidation process is easily controlled and may be conpletely automated.

1. The oxidation of paraffin wax was studied under various hydrodynamic conditions in the linear air velocity range over the total section of the column of 0.05 to 0.35 m/sec. The process rate was highest at air supply rates of 0.2 m/sec and above. 2. It is shown that oxidation of solid paraffin wax at 130°C with a specific air flow rate of 1.08 m3/kg · h is in the kinetic region, with specific flow rate of 1.08 to 0.36 m3/kg · h in the transitional region and at flow rates below 0.27 m3/kg · h in the diffusion region. 3. In designing industrial foam type equipment the linear air velocity should be in the range 0.15 to 0.2 m/sec and the specific air flow rate 0.4 to 1 m3/kg · h.

1. It is shown that the method of [4] can be used to analyze an industrial plant for continuous oxidation of paraffin in a layer of foam. 2. Numerical values are found for the coefficients of mass transfer for industrial plants. 3. Data are given which characterize the operation of industrial plants for oxidation of paraffin foam. 4. The authors demonstrate the effect of the specific air-flow rate and temperature on the change in acid number.

1. The experimental study proved that the conditions of the liquid phase oxidation of hydrocarbons can be varied over a broad range in the various process stages when a multisection foam apparatus is used. In this apparatus it is possible to study the effect of the separate factors on the oxidation of hydrocarbons in the various process stages. 2. The problem of trapping the volatile reaction products can be efficiently solved by the use of a multisection apparatus.