Investigation of Changing Volt-Ampere Characteristics of AlGaInP Heterostructures with Multiple Quantum Wells under Ionizing Radiation

The results of research into degradation of volt-ampere characteristics of light emitting diodes produced on the base of AlGaInP heterostructures with multiple quantum wells are presented on the example of light emitting diodes (emission wavelengths 623 nm and 590 nm) under gamma quantum and fast neutron radiation in passive powering mode. The shifts of volt-ampere characteristics into the higher voltage range have been observed in conditions of increasing neutron fluence and radiation dose. The observed increase in the resistance of ohmic contacts is caused by the rising resistance of adjacent area, which in its turn results from the changing mobility of charge carriers. The latter varies with the growth of introduced defects under irradiation. Two different areas of current generation have been identified. A mechanism of current generation depends on injected charge carriers in the range of mid-level electron injection. Moreover, the range of high electron injection is distinguished by changing resistance of light emitting diode cores alongside with current generation conditioned by charge carrier injection

Structure of 5-nitro-2-tosylaminobenzaldehyde di(morpholin-4-yl)aminal Complex with Carbon Tetrachloride

The 5-nitro-2-tosylaminobenzaldehyde di(morpholin-4-yl)aminal forms a stable complex with carbon tetrachloride in the crystal phase. X-ray structural study of this complex indicates an essentially shortened intermolecular contact of 2.89 Å between the oxygen atom of the nitro group and one of the chlorine atom of the CCI4 molecule. Quantum-chemical calculations by semiempirical AMI method showed that the formation of such complex did not cause considerable decrease of system energy or change of charge distribution in molecules. It was supposed that this associate has van der Waals character

Gate-dependent non-linear Hall effect at room temperature in topological semimetal GeTe

We experimentally investigate non-linear Hall effect as zero-frequency and second-harmonic transverse voltage responses to ac electric current for topological semimetal GeTe. A thick single-crystal GeTe flake is placed on the Si/SiO$_2$ substrate, where the p-doped Si layer serves as a gate electrode. We confirm, that electron concentration is not gate-sensitive in thick GeTe flakes due to the gate field screening by bulk carriers. In contrast, by transverse voltage measurements, we demonstrate that the non-linear Hall effect shows pronounced dependence on the gate electric field at room temperature. Since the non-linear Hall effect is a direct consequence of a Berry curvature dipole in topological media, our observations indicate that Berry curvature can be controlled by the gate electric field. This experimental observation can be understood as a result of the known dependence of giant Rashba splitting on the external electric field in GeTe. For possible applications, the zero-frequency gate-controlled non-linear Hall effect can be used for the efficient broad-band rectification

Current-induced control of the polarization state in a polar metal based heterostructure SnSe/WTe2_2

The concept of a polar metal proposes new approach of current-induced polarization control for ferroelectrics. We fabricate SnSe/WTe$_2$ heterostructure to experimentally investigate charge transport between two ferroelectric van der Waals materials with different polarization directions. WTe$_2$ is a polar metal with out-of-plane ferroelectric polarization, while SnSe ferroelectric semiconductor is polarized in-plane, so one should expect complicated polarization structure at the SnSe/WTe$_2$ interface. We study $dI/dV(V)$ curves, which demonstrate sharp symmetric drop to zero $dI/dV$ differential conductance at some threshold bias voltages $\pm V_{th}$, which are nearly symmetric in respect to the bias sign. While the gate electric field is too small to noticeably affect the carrier concentration, the positive and negative threshold positions are sensitive to the gate voltage. Also, SnSe/WTe$_2$ heterostructure shows re-entrant transition to the low-conductive $dI/dV=0$ state for abrupt change of the bias voltage even below the threshold values. This behavior can not be observed for single SnSe or WTe$_2$ flakes, so we interpret it as a result of the SnSe/WTe$_2$ interface coupling. In this case, some threshold value of the electric field at the SnSe/WTe$_2$ interface is enough to drive 90$^\circ$ change of the initial SnSe in-plane polarization in the overlap region. The polarization mismatch leads to the significant interface resistance contribution, analogously to the scattering of the charge carriers on the domain walls. Thus, we demonstrate polarization state control by electron transport through the SnSe/WTe$_2$ interface

Switching ferroelectricity in SnSe across diffusionless martensitic phase transition

We experimentally investigate transport properties of a hybrid structure, which consists of a thin single crystal SnSe flake on a top of 5~$\mu$m spaced Au leads. The structure initially is in highly-conductive state, while it can be switched to low-conductive one at high currents due to the Joule heating of the sample, which should be identified as $\alpha$-$Pnma$ -- $\beta$-$Cmcm$ diffusionless martensitic phase transition in SnSe. For highly-conductive state, there is significant hysteresis in $dI/dV(V)$ curves at low biases, so the sample conductance depends on the sign of the applied bias change. This hysteretic behavior reflects slow relaxation due to additional polarization current in the ferroelectric SnSe phase, which we confirm by direct measurement of time-dependent relaxation curves. In contrast, we observe no noticeable relaxation or low-bias hysteresis for the quenched $\beta$-$Cmcm$ low-conductive phase. Thus, ferroelectric behavior can be switched on or off in transport through hybrid SnSe structure by controllable $\alpha$-$Pnma$ -- $\beta$-$Cmcm$ phase transition. This result can also be important for nonvolatile memory development, e.g. phase change memory for neuromorphic computations or other applications in artificial intelligence and modern electronics

Correlation of competitive market structure and innovative activity of oil and fat companies

The article considers the current state of the oil and fat industry from the standpoint of its competitive structure, and identifies the main problems of its development in Ukraine. It was established that the fat-oil sub-complex is one of the most promising sectors of the national economy. The sub-complex fully meets the needs of the domestic market in oily products and allows exporting products to foreign markets. In addition, its role is important in shaping the consumption fund, solving the problems of internal food security, ensuring currency and tax revenues, as well as solving a number of social problems through the creation of a significant number of jobs in the fat and oil subcomplex and related industries. The industry has a high level of monopolization. Most enterprises are part of large corporate agribusiness formations, agroholdings and multinational companies. Monopolists can dictate their conditions both in the market of raw materials and in the market of finished products by consolidating their companies. It allows them to regulate profitability of production and to reduce the influence of competitors. Competition in the global markets of vegetable oil has escalated in recent years. A complex of problems, the solution of which will largely determine the development of the oil and fat industry in the long term, is connected both with the increase in the raw material base and the expansion of various types of oilseeds production, and with the modernization and expansion of production capacities on the basis of scientific and technological progress, the development of a new innovation-investment strategy of forming industry competitive advantages of oil and fat companies by improving competition policy

Semantic Series as a Discourse Analysis Tool (Discourse about Generations)

The question of methods of discourse semantics modeling, understood as a content-thematic community of texts, is considered. The novelty of the research is seen in the expansion of the methodological tools in the study of discourse as an array of texts, in the refinement of supra-individual knowledge about an important social phenomenon. The relevance of the study is due to the interest of the humanities in the theory of generations, which has not yet received a linguistic response. Attention is paid to the ideas and techniques that make it possible to derive text-discursive meanings on the basis of isotopy and related concepts, in particular the concept of a semantic series. The construction of semantic series as a proven technique for analyzing literary texts is extrapolated to the study of discourse formed by a collective speech subject, which is the author’s version of the presentation of speech systemicity. The semantic series identified in the aggregate of fragments of different types of texts containing the lexeme generation are analyzed. Attention is paid to the series that objectify such semantic blocks as self-presentation of subjects of speech by belonging to a generation, categorization of generations, generational values. The author compares the meanings, actualized by the semantic series, with the provisions of the interdisciplinary theory of generations, developed by N. Howe and W. Strauss, proves a partial intersection of theoretical provisions and everyday ideas