Search

Introduction. This article analyzes the behavior of religious actors during the Russian Federation's special military operation in Ukraine. Ecclesiastical (church) diplomacy has gained a lot of attention from the media because of its attempts to resolve the situation. The Ukrainian crisis demonstrates that the relationship between religious actors and states is evolving from a secular model to a post-secular model, the general outline of which, however, has not yet been clearly formed. One way or another, the religious factor has become one of the key factors in the formula for analyzing and solving the Ukrainian crisis.Materials and methods. The theoretical and methodological basis of the study, in addition to general scientific methods, were special political science research tools - actor and institutional approaches, comparative method, case study method.Results of the research. The study revealed the key importance of Christian religious organizations, which more than others seek to participate in the resolution of the Ukrainian crisis and offer a variety of measures. At the same time, there is a commonality of positions between the official authorities of most states and the higher church hierarchs, based on their location. Such political interdependance of church and secular authorities has mixed consequences. Religious actors everywhere reduce the potential of their international political subjectivity. This is particularly noticeable in the case of the Russian Orthodox Church, which is substantially strengthening its position inside Russia but is becoming less influential outside it.Discussions and conclusions. We argue that the world political system will continue to drift away from the ideals of the Modernity and its secular principle. At the same time it is hardly possible to talk about archaization in the form of desecularization. Rather the Ukrainian crisis promotes a post-secular model, a new balance between religion, state power and society. Meanwhile, the confrontational nature of interaction between Christian churches during the Russian special military operation in Ukraine further weakens the ecumenical movement and generates new schisms between Orthodox churches. This also affects the identitarian profile of the societies of the Euro-Atlantic and Eastern European states, which is becoming more flattened.

The problem of divided societies and divisions in societies acquires special significance against the background of growing socio-political tensions in the internal and external political dimensions around the world. The West is ceasing to be an area of predominant tranquility and wellbeing. In recent years, in European societies a trend of increasing divisions has also emerged. The article analyzes old and new socio-political divisions (cleavages) within the Portuguese society. The choice of Portugal as a case study is due to the combination of several factors: the memory of the Carnation Revolution, the attitude towards the European project, the imperial past, Catholicism/secularism, and the historical legacy of the Salazar dictatorship. The theoretical and methodological framework of the study is based on the use of the concept of divided societies and constructivism as the main epistemological tools, while the country studies analysis is also applied. The authors attempt not only to identify the basic socio-cultural divisions in the contemporary Portuguese society, but also answer the question of whether it is possible to speak of a divided society in relation to the Portuguese case. The emphasis is placed on the peculiarities of Portugal’s historical path as a post-imperial state whose specificity is largely due, first, to the heritage of the Portuguese maritime empire, and, second, to the legacy of the 1974 Carnation Revolution. The key cleavages that are at the center of the analysis are the legacy of the Carnation Revolution, the European project, the imperial legacy, the religious configuration, and the Salazar heritage. The conclusion is that the Portuguese society has managed to avoid the most negative scenario of the development of the situation and has a chance of consolidation.

A complex study was performed on a set of AlGaN/GaN high-electron-mobility transistor structures grown by metalorganic vapor phase epitaxy on miscut Si(111) wafers with a highly resistive epitaxial Si layer to investigate the influence of substrate miscut on their properties. The results showed that wafer misorientation had an influence on the strain evolution during the growth and surface morphology, and could have a strong impact on the mobility of 2D electron gas, with a weak optimum at 0.5° miscut angle. A numerical analysis revealed that the interface roughness was a main parameter responsible for the variation in electron mobility.

The article analyzes the phenomenon of new populism in Central and Eastern Europe, taking as an example such countries as Hungary and Poland. The object of research is scientific discourse, and the subject is its segment, directly or indirectly related to populism in CEE. The main problems, aspects and positions that exist in the scientific community on the topic of populism are identified. This article explores the questions of whether populists in CEE countries are bearers of the potential for alternativeism.The piece also raises the problem of the model of the world order and the possibility of projecting an Eastern European alternative development-Most attention is paid to the answers to these research questions. In addition, the article outlines possible prospects for the development of the scientific discourse of populism, including in a comparative political key.

The COVID-19 pandemic has rapidly and synchronously changed the lives of billions of people all over the planet. The economic, social, and political problems were entwined in tight contradictions. The impact of the COVID-19 pandemic on international and national political issues has been the focus of attention of academia around the world since early 2020. The primary attention has been focused on international and national levels. At the same time, the subnational and local dimensions of the corona crisis "elude" the political science community. Nevertheless, fighting against the new biogenic danger changes the redistribution of power between the national, subnational, and local levels. The article analyses this redistribution and presents its preliminary due to the incompleteness of the pandemic results. It seeks to identify the main patterns of a new round of the evolution of subsidiarity associated with the COVID-19 pandemic. What role does COVID-subsidiarity play now, and what are its prospects in the post-pandemic world? The article employs the concept of megatrends and comparative methods to answer this question. The results show that extraordinary powers have been redistributed worldwide from the national to the subnational level. The essential characteristic of COVID-subsidiarity is the emergence of emergency powers at the subnational and local levels. It happens in states with different political regimes and different political cultures. It is likely that even after the end of the current pandemic, in some cases, the subnational regions will try to retain the expanded powers they acquired during the emergency. This is part of a broader process of transformation of the modern state and its adaptation to the newly emerging political organization of the world.

A family of unusual octacopper cage methylsilsesquioxanes 1–4 were prepared and characterized. Features of their cagelike (prismatic) structure were established using X-ray diffraction studies. Effects of distortion of prismatic cages 1–4 due to variation of (i) additional alkaline metal ions (K, Rb, or Cs), (ii) combination of solvating ligands, and (iii) nature of encapsulating species were found. Opportunities for the design of supramolecular 1D extended structures were found. These opportunities are based on (i) formate linkers between copper centers (in the case of Cu8K2-based compound 2) or (ii) crown ether-like contacts between cesium ions and siloxane cycles (in the case of Cu8Cs2-based compound 4). Cu8Cs2-complex 4 was evaluated in the catalysis of alkanes and alcohols. Complex 4 exhibits high catalytic activity. The yield of cyclohexane oxidation products is 35%. The presence of nitric acid is necessary as a co-catalyst. The oxidation of alcohols with the participation of complex 4 as a catalyst and tert-butyl hydroperoxide as an oxidizer also proceeds in high yields of up to 98%.

В данной работе было исследовано влияние легирования барьерного слоя AlGaN примесью n-типа в одно- и трёхканальных AlGaN/AlN/GaN гетероструктурах на их электрические свойства. Установлено, что оптимальная толщина i-AlGaN спейсера составляет 3 нм, а оптимальная концентрация Si примеси в n-AlGaN составляет 7·1018 см-3. Наименьшее рассчитанное слоевое сопротивление трёхканальной структуры при комнатной температуре ~90 Ом/квадрат, что в три раза меньше, чем у одноканальной структуры., The influence of n-type doping of the AlGaN barrier layer in AlGaN/AlN/GaN single- and triple-channel heterostructures on their electrical properties was studied. It was found that the optimal thickness of i-AlGaN spacer is 3 nm, and the Si concentration in n-AlGaN is 7·1018 cm-3. The lowest predicted sheet resistance at room temperature for the triple-channel structure of the optimal design is ~90 Ω sq-1., three times lower than that of the single-channel structure.

Hybrid structures combining ferromagnetic (FM) and semiconductor constituents have great potential for future applications in the field of spintronics. A systematic approach to study spin-dependent transport in the GaMnAs/GaAs/InGaAs quantum well (QW) hybrid structure with a few nanometer thick GaAs barrier is developed. It is demonstrated that a combination of spin electromotive force measurements and photoluminescence detection provides a powerful tool for studying the properties of such hybrid structures and allows to resolve the dynamic FM proximity effect on a nanometer scale. The method can be generalized on various systems including rapidly developing 2D van der Waals materials.

The paper presents the analysis of modern political communications in terms of availability of adequate information and scientific and educational resources within the political discourse. The theoretical and methodological framework of the article is based on political communication studies being the most essential focus area of modern political science. The authors present the analysis of history and the current state of political communication issues being an element and a tool to study political processes, identify the specific characteristics of public political discourse in the context of existing contradictions in social development. To resolve some of the difficulties, the authors present a new unique interface (link) between political science and political discourse – electronic resources of systematized political science publications and political documents in the form of online libraries with books, articles, reports, documents available – ‘Library of a Political Scientist’ and ‘Library of a Conflictologist’, which are a unique form of inventory of available scientific and educational resources. ‘The Library of a Political Scientist’ is more universal in nature and is intended for rather broad audience. ‘The Library of a Conflictologist’, although being a more specialized information and analytical resource, at the same time contains multimedia (photos, videos, maps, infographics) and interactive (test game on six conflicts) components, which is in line with the modern educational and research paradigm. These resources are a new way of filing political science publications; they are intended to maintain by means of information and references modern scientific discourse in Russia on topical issues of Russian national and international policy, as well as international political conflictology in the geopolitical arena of Russian interests.

As relations between the Russian Federation and the West continue to deteriorate, traditional diplomatic instruments become less eff ective. Conversely, the role of alternative diplomatic channels is growing. However, the Russian foreign policy still tends to underestimate their potential. In particular, the soft power potential of the Russian regions appears to be largerly under-utilized. The paper starts with a general overview of the specifi c features of sub-state/sub-national actors in the world politics. In particular, the author emphasizes that these actors are synthetic by nature, which predetermines their particular role on the international scene, as they can use policy instruments specifi c to both state and non-state actors. The author provides a model for classifi cation of the Russian regions based on the level of their international activity. The paper examines by what means the international activities of the regions can infl uence the interstate relations and outlines two basic frameworks for joint actions of the federal center and the regions on the international arena: ‘culture and image-building’ and ‘political plus’. The author emphasizes the importance of the federal-regional cooperation in addressing foreign policy issues, particularly, in response to international crises. The paper assesses the capacity of diff erent Russian sub-national actors to actively participate through their soft power potential in normalization of interstate relations. The author concludes that this potential could be successfully integrated into the Russian foreign policy strategy. However, in order to improve the quality of the federal-regional cooperation on the foreign policy issues, it is necessary to develop a new framework for interaction between the federal center and the regions of the Russian Federation, based on greater involvement of regional representatives in the decision-making process (which implies reassessment of the entire system of federal relations).

The present world is characterized by the growth of conflicts. Dividing lines and fractures are increasingly appearing in societies. Migration reinforces such phenomena. The West is no longer an area of stability and prosperity. Moreover, in the last two decades, the problem of integrating the descendants of migrants into society has become clear. In this regard, the scientific discussions of cultural identity acquire a high practical significance. The paper presents an analysis of the scientific discourse on the Muslim issue in the UK. The choice of the case is due to the fact that the UK is a typical Western state, where there is a steady trend to strengthen the cleavage of society. At the same time, it is noted that migration has become one of the key processes in the history of the United Kingdom. The authors apply the concepts of a divided society and responsible development. It is noted that in practice multiculturalism is changing to interculturalism as a more adequate concept of solving existing problems. According to the authors, the ethno-religious discourse on the issue of the Muslim diaspora in the UK consists of four areas: migration, school and higher education, gender, and radicalization of young people. Discourses on the problems of migration policy and functioning of diasporas, Muslim education, gender equality, and radicalization of Islamic youth can be considered derived from a higher discourse – the discourse of identity, which is based on value-worldview aspects. In conclusion, it is noted that negative processes are taking place in British society, which are of strategic importance for responsible development. According to the authors, success in overcoming divisions in British society will depend on coordinated planned actions at all levels (international, national, regional, local). “Indigenous” residents and the Muslim diaspora need to build a model of partnership, which implies mutual responsibility. The analysis of scientific discourses presented in the article inspires moderate optimism, as it offers well-founded and concrete solutions to the existing problems of British society. Although British society is divided, British scientific discourse has a common platform where researchers of different backgrounds and faiths successfully engage in dialogue.

A genetic algorithm was employed to optimize the Si doping profile of luminescence InGaN-based heterostructures. It was shown that, in the optimized structure, a ‘parasitic’ luminescence from GaN barrier layers could be suppressed while the efficiency remained the same as that of the best uniformly doped structure. Moreover, the optimized structure had a 2.6 times lower total Si concentration, which could be beneficial in terms of crystal quality of the grown layers., В данной работе представлены результаты оптимизации профиля легирования барьерного слоя в структурах на основе InGaN методом генетического алгоритма. Показано, что в оптимизированной структуре интенсивность «паразитной» люминесценции из GaN слоёв может быть существенно снижена, при этом эффективность излучения из квантовых ям остаётся такой же, как и в лучшей структуре с однородно легированным барьером. Кроме того, суммарная концентрация кремния в оптимизированной структуре в 2,6 раза ниже, что также является преимуществом с точки зрения кристаллического качества выращенных слоёв.

The broadening of the spectral linewidth of the GaN/InGaN/GaN quantum wells caused by the random distribution of indium and gallium atoms in the cation sublattice was analyzed theoretically. The calculated values of the full width at half maximum of the emission spectra at low temperature are much smaller than the usually observed experimental values, indicating that the emission linewidth of the InGaN quantum wells is mostly determined by other broadening mechanisms (e.g. indium clustering, quantum well width fluctuations, background impurity broadening, etc.).

Review of the book by Logvinova I.V. Coordination of International and Foreign Economic Connections of the Russian Federation’s regions. Moscow, MGIMO, 2018. 238 p. (In Russian).

The paper is devoted to the problem of asymmetrical international interaction of sub-state actors. It touches upon the erosion of Westphalian sovereignty at present time. This problem is under discussion in conjunction with the evolution of federalism. Author attempts to clarify the relation of international activity of world politics sub-state actors and type of interaction between central and regional levels of government. For this purpose the article presents the analysis of the cooperation between the Republic of Komi (part of Russian Federation) and the Republic of Hungary in the first half of the 1990s. In addition author focuses on the role of international relations of sub-state actors in the democratic transition. The main method of the investigation is historical institutionalism. This research method provides a necessary result. The investigation based on data from the Foreign policy archive of the Russian Federation and publications in Hungarian and Russian newspapers. There are foreign and Russian research papers on the question. Scientists from different fields develop this issue. For carrying out the purpose of investigation offer typology of Russian regions regarding to their external relations, indicate the possible definitions of the key terminology of international activities of Russian regions and is a brief overview of the establishment of Russian-Hungarian relations on a new base in the late Soviet and early post-Soviet periods. It should be noted that the model of interaction between the Komi Republic and Hungary is typical of many of the basic parameters for international activities of Russian regions in the chronological framework. In conclusion the paper reads that to the medium of the 1990s came a partnership type of relationship between Сentre and Komi concerning Komi-Hungarian cooperation. This fact proves the possibility of the positive role of asymmetric international relations of sub-state actors, including the period of democratic transition.

The paper presents the derivation of a model for minority carriers collection based on the reciprocity theorem and its application for determination of hole diffusion length in n-GaN by means of photoluminescence. The estimated hole diffusion lengths at room temperature are 110 nm and 194 nm in the case of low and high excitation, respectively, which could be explained by saturation of non-radiative recombination centers in bulk GaN and at the surface with photogenerated carriers.

The influence of two types of AlN/GaN interfacial non-idealities, namely unintentional Ga incorporation into AlN spacer and blurring of the spacer due to Al and/or Ga atomic diffusion on the mobility and density of two-dimensional electron gas in AlGaN/AlN/GaN heterostructure was studied theoretically. It was found that moderate amount of GaN in the nominal AlN spacer does not affect much the mobility and density of 2DEG as long as the interface is abrupt. In contrast, the blurring of AlN/GaN interface was found to have a significant impact on the mobility and sheet resistance of the structure since the GaN channel actually becomes AlGaN and alloy-disorder scattering takes place.

The influence of dislocations on luminescence of InGaN/GaN multiple quantum wells was investigated by temperature-dependent and time-resolved room-temperature photoluminescence measurements and analyzed via localized-state ensemble model. The results show that dislocations decrease non-radiative recombination time and do not affect either radiative recombination time or non-radiative recombination mechanism. Moreover, dislocation-related broadening, increasing linearly with increased dislocation density, was found to take place. However, a significant part of spectral width (∼55 meV) is not defined by either dislocation-induced or alloy- and thermally-induced broadening, revealing the existence of other broadening mechanisms (e.g. carrier–carrier scattering-induced broadening).

Emission of terahertz radiation from a AlGaN/GaN/Al $_{\mathbf {2}} \mathbf {O} _{\mathbf {3\, }}$ heterostructure with a surface metal grating is investigated under conditions of 2D electron heating in a lateral electric field. The studies are performed under essentially nonequilibrium conditions when the effective temperatures of 2D electrons and 2D plasmons are several times higher than the lattice temperature. This makes it possible to observe and explore high-quality peaks of intense THz radiation corresponding to 2D plasmon resonance.

Temperature-dependent luminescent properties of dual-wavelength blue-cyan light emitting diodes (LEDs) based on InGaN quantum wells were investigated by means of photo- (PL) and electroluminescence (EL) spectroscopy techniques. The results showed that the thickness of the interwell GaN layer had a great impact on the spectra (especially on the EL ones) at room temperature. At low temperatures, however, the EL spectra are nearly identical for all the samples regardless the differences at room temperature. The differences in the temperature behavior of the above-bandgap PL spectra can be explained in terms of different areas of carrier collection region for the samples with different interwell barrier thickness, as evidenced by the below-bandgap PL spectra measurements as well as by the Beer's law calculations. Additionally, an anomalous increase of the above-bandgap PL intensity is observed at the temperature range of ~120–150 K, which is absent in the case of below-bandgap excitation.

High electron mobility transistors (HEMTs) technologies based on AlGaN/GaN and InAlN/GaN heterostructures have been developed. The research focused on influence of epitaxial growth conditions and buffer doping profiles on electrical properties HEMTs. An output power density of 4W/mm at 17 GHz was demonstrated for InAlN/GaN HEMTs and 7W/mm at 10 GHz for AlGaN/GaN HEMTs.

The article is in the genre of the review for textbook O. V. Plotnikova and O. Y. Dubrovina International relations of the regions States: characteristics and features (Moscow: Norma; INFRA-M, 2016. 192 p.). Textbook on international activities of sub-state/subnational actors in international relations. Under the sub-state/subnational actors refers to the regions of the States. The authors propose an along with interstate relations (first level) and supranational organizations (second level) to distinguish a third level of international relations - international relations of the regions in Federal and unitary States. The topic is very relevant due to the ongoing restructuring of the architecture of international relations and world politics. In addition, these processes lead to involvement in international relations new actors. The resulting configuration and the role of traditional players. In addition to long-term evolutionary processes, we should not forget about the position of Russia in the last few years. It is obvious that the current tensions around the Russian Federation may not be fully resolved with the old methods. At the same time, sub-state/ subnational actors as subjects of a combined nature, the role played by regions of the Russian Federation, able to combine harmoniously in its international activities as the techniques characteristic of the traditional actors - States and developments in the tools of non-traditional actors - international non-governmental and non-profit organizations etc. As a result of positive results can be achieved faster and at the interstate level. The review considers the subject and the relevance of the topic, presents the analysis of the content of the work. Marked strengths of the textbook, including those associated with the consideration of the diagonal ties and the political components in the international activities of the regions. In addition to the advantages, attention is paid to the analysis of controversial moments. Some authors benefits seem too rigid or insufficiently substantiated. Noted and some defects. The conclusion about the serious significance of this educational publication is not only for a student audience, but also for practitioners.

Using a considerable variety of sources (chronicles, hagiography, charters, letters) the author of the present article shows a process of formation of the system of the Breton bishoprics during the Carolingian era, when this land was a part of the Frankish empire. There were no regular episcopal sees in Brittany before the 9th century: Dol and Léon were monastery-bishoprics; Tréguier and Aleth, possibly, had the same nature. Bishops appeared there only from time to time. In the middle of the 9th century there were sees in Aleth, Quimper, Léon, and Dol. And they were substituted regularly. Obviously, an attempt to establish episcopal sees in Tréguier and Saint-Brieuc was vain. Along with a territorial expansion of the power of the Breton duke three others bishoprics founded in the Roman and post-Roman times — Nantes, Rennes, and Vannes — became parts of the Breton church. The sought of duke Nominoe for the independence from West-Frankish kingdom led to the «schism» of 849 which actually meant a separation of the most of the Breton bishoprics from the Gallic Church. King Salomon in 860s tried to promote the see of Dol to a metropolitan grade, but with no success due to determined resistance of the pope Nicolas I and the Frankish bishops. But in spite of the absence of archbishopric in Brittany the church of the region from the last third of the ninth century onwards run its quite different from the rest of the Western Сhurch way of life with its own synods and traditions. In this sense the Breton Church resembled other Celtic Churches of the Early Middle Ages.

The article is in the genre of the review for textbook O. V. Plotnikova and O. Y. Dubrovina International relations of the regions States: characteristics and features (Moscow: Norma; INFRA-M, 2016. 192 p.). Textbook on international activities of sub-state/subnational actors in international relations. Under the sub-state/subnational actors refers to the regions of the States. The authors propose an along with interstate relations (first level) and supranational organizations (second level) to distinguish a third level of international relations - international relations of the regions in Federal and unitary States. The topic is very relevant due to the ongoing restructuring of the architecture of international relations and world politics. In addition, these processes lead to involvement in international relations new actors. The resulting configuration and the role of traditional players. In addition to long-term evolutionary processes, we should not forget about the position of Russia in the last few years. It is obvious that the current tensions around the Russian Federation may not be fully resolved with the old methods. At the same time, sub-state/ subnational actors as subjects of a combined nature, the role played by regions of the Russian Federation, able to combine harmoniously in its international activities as the techniques characteristic of the traditional actors - States and developments in the tools of non-traditional actors - international non-governmental and non-profit organizations etc. As a result of positive results can be achieved faster and at the interstate level. The review considers the subject and the relevance of the topic, presents the analysis of the content of the work. Marked strengths of the textbook, including those associated with the consideration of the diagonal ties and the political components in the international activities of the regions. In addition to the advantages, attention is paid to the analysis of controversial moments. Some authors benefits seem too rigid or insufficiently substantiated. Noted and some defects. The conclusion about the serious significance of this educational publication is not only for a student audience, but also for practitioners.

The effect of the Fe doping profile of the GaN buffer layer in the heterostructures for high-electron mobility transistors was studied experimentally and by computer simulation. The exponential Fe tail extending to the nominally undoped layers may greatly affect the properties of the structure. Reducing the distance between the channel and the Fe-doped buffer to less than 1 μm results in a decrease in the density and mobility of the two-dimensional electron gas. It also leads to the higher off-state avalanche breakdown voltage and reduced leakage current. A good agreement between simulation and experimental data is obtained when taking into account a Fe segregation effect, while an abrupt doping profile lead to significant discrepancies between them

We report on studies of electrically excited non-equilibrium 2D electrons and 2D plasmons in an AlGaN/GaN nanostructure. Optical access to 2D plasmons is provided by means of a metal grating fabricated at the nanostructure surface, while the properties of 2D electrons are examined in the samples without metal grating. The paper focuses on the creation of highly non-equilibrium conditions when the effective temperature of 2D electrons is much higher than the crystal lattice temperature. Such conditions are realized by applying short electrical pulses with a low repetition frequency. A method has been developed for independently determining the temperature of hot electrons and the temperature of the crystal lattice under an applied electric field. It has been shown that under highly non-equilibrium conditions the spectral density of terahertz electroluminescence of 2D plasmons can significantly exceed that of 2D electrons at a certain frequency.

Simulation analysis of III-N two-dimensional electron gas-based structures that could be used for stable monolithically integrated enhancement/depletion-mode circuits was carried out. Three different designs were proposed and analysed, including a novel p-GaN/AlN-GaN SPSL/GaN, which is expected to have lower ON-state resistance and higher transconductance than conventional normally-off GaN-based transistors.

Dependence of electroluminescence spectrum shape of blue-cyan InGaN-based dichromatic double quantum well light emitting diodes on the thickness and doping level of the barrier between quantum wells was investigated numerically and experimentally.

The article describes information about the application of digital technologies for the calculation of heat supply elements. The algorithm and digital platforms for computing automation are developed. В работе изложена информация о применении цифровых технологий для расчетов элементов теплоснабжения. Разработан алгоритм и цифровые платформы для автоматизации вычислений.

Terahertz radiation emission from an electrically excited AlGaN/GaN heterostructure with a surface metal grating was studied under conditions of two-dimensional (2D) electron heating by the lateral electric field. Intensive peaks related to nonequilibrium 2D plasmons were revealed in the terahertz emission spectra with up to 4 times selective amplification of the radiation emission in the vicinity of 2D plasmon resonance. This selective emission was shown to be frequency-controllable by the grating period. Exact spectral positions of the 2D plasmon resonances were preliminarily experimentally detected with the help of equilibrium transmission spectra measured at various temperatures. The resonance positions are in a satisfactory agreement with the results of theoretical simulation of the transmission spectra performed using a rigorous solution of Maxwell’s equations. The effective temperature of hot 2D electrons was determined by means of I– V characteristics and their analysis using the power balance equation. It was shown that for a given electric field, the effective temperature of nonequilibrium 2D plasmons is close to the hot 2D electron temperature. The work may have applications in GaN-based electrically pumped emitters of terahertz radiation.Terahertz radiation emission from an electrically excited AlGaN/GaN heterostructure with a surface metal grating was studied under conditions of two-dimensional (2D) electron heating by the lateral electric field. Intensive peaks related to nonequilibrium 2D plasmons were revealed in the terahertz emission spectra with up to 4 times selective amplification of the radiation emission in the vicinity of 2D plasmon resonance. This selective emission was shown to be frequency-controllable by the grating period. Exact spectral positions of the 2D plasmon resonances were preliminarily experimentally detected with the help of equilibrium transmission spectra measured at various temperatures. The resonance positions are in a satisfactory agreement with the results of theoretical simulation of the transmission spectra performed using a rigorous solution of Maxwell’s equations. The effective temperature of hot 2D electrons was determined by means of I– V characteristics and their analysis using the power balance ...

Calculational analysis of different scattering mechanisms of two-dimensional electron gas in AlGaN/(AlN)/GaN and InAlN/(AlN)/GaN high-electron mobility transistors was carried out. It was found that the mobility of AlGaN-based structures at room temperature is mainly limited by inherent scattering mechanisms (namely, optical and acoustic phonon scattering), while the mobility in our InAlN-based structures is limited by the interface roughness scattering. The low-temperature mobility is found to be limited by the interface roughness scattering for both AlGaN- and InAlN-based structures.

Synchronous extraction of energy from cavity resonators for X-band microwave radiation through a compact packet of five interference switches based on H tees has been experimentally analyzed. It is shown that switches can be completely synchronized and the synchronization conditions are determined. Microwave pulses have been generated upon synchronous extraction of energy from five single-mode cavities (power ∼0.8 MW, gain ∼12 dB, and width ∼3.2 ns) and from one superdimensional cavity (power ∼2.2 MW, gain ∼16.5 dB, and width ∼3.5 ns). The operation limits of X- and S-band microwave compressors with extraction of energy through a packet are estimated.

Optical and structural properties of thick InGaN layers grown by MOCVD and MBE were studied by photoluminescence, optical transmission and Raman spectroscopies and X-ray diffraction analysis. Optical bandgap, Urbach energy, and full widths at half maximum (FWHM) of photoluminescence and Raman spectra depending on the InGaN alloy composition were determined experimentally. Minimal theoretical linewidth of photoluminescence spectra resulted from random distribution of In and Ga atoms in cation sublattice was calculated.

The series of InAlGaN LED structures containing two different quantum wells emitting at wavelengths of ~ 430 nm and ~ 490 nm was grown. The influence of the quantum wells order, thickness of the barrier between the wells and its doping level on the optical properties was studied by photo- and electro-luminescence measurements. It was found that the quantum well with longer-wavelength emission is preferable to be located farther from a player than the shorter-wavelength quantum well to obtain emission from both QWs. Variation of the thickness of the barrier between the QWs and its doping level allows controlling the intensity ratio of two emission peaks.

Real-time locating systems (RTLS) are systems, which can automatically identify and track the objects. Such a system can be helpful at university in a way that students can find in which auditorium a professor is present at that moment or at hospital for the fast detection of rooms in which nurses are present.In this thesis the prototype of the Real-time locating system based on the Bluetooth Low Energy technology was build and demonstrated. System was developed using Reactive Blocks SDK. The development, using SDK, is turning the ordinary program codding process to the visual process. Raspberry Pi was chosen as hardware solution for the system. Work shows solutions on problems, which can occur during working with Bluetooth. The results of experiments, which were performed to establish the quality of measure of RSSI value, were demonstrated using the developed system. The results include different combinations of independent variables such as: speed of movement of an object, a type of an object, a scanning interval, a type of network connection and a type of environment (with wall or without wall between the advertising signal and the zone scanner). Further, these results were used for a development of an algorithm for a zone detection. The results of the algorithm were demonstrated in additional experiments, which showed the possibility of the zone detection by the developed system.A discussion about the correctness of technic approaches, which were used in the work, was presented in a conclusion. In addition, a future work that includes new ideas and suggestions for increasing and improving a quality of the zone detection was presented.

The first results of an experimental investigation of the synchronization of two resonant microwave compressors by a laser beam are presented. It is shown that almost complete synchronization can be achieved and the corresponding conditions are determined. Using S-band compressors, a total output signal power of about 220 MW was obtained for 100% summed signals. The possibility of increasing the total output power up to 450 MW is justified.