The production of epitaxial layers requires the search for simple, technologically advanced and accurate methods for assessing the basic properties of layers and compositions made from them. The issue is especially acute for developers of multistage photovoltaic converters (PVCs) for space applications, which are distinguished by a complex heterostructure, including 5 or more p-n junctions and a large area. The work carried out a search for an optimal method for studying the electrical characteristics of thin semiconductor layers of the n/p-InxGa1-xAs type with different doping levels. The main task is to measure the basic electrical characteristics in various ways: resistivity (conductivity), concentration of the main charge carriers, the dependence of the main electrical parameters on the type and level of doping and their comparison. Using the example of p- and n-type In0.01Ga0.99As solid solutions obtained by MOS-hydride epitaxy, a technique for studying the main electrical characteristics of epitaxial layers is proposed, taking into account the assessment of homogeneity on large-area samples. A comparison of the results obtained by various methods is presented: photoluminescence, non-contact measurement of surface resistance, Van der Pauw (Hall effect) and capacitance-voltage (electrochemical profiling (ECP), in situ control methods. Based on the results obtained and comparison with literature data, conclusions are drawn about the need, sufficiency and complementarity of methods for monitoring and studying semiconductor epitaxial structures.

133 Cs NMR was employed to study the structural characteristics and properties of perovskites at the atomic level. CsBi x Pb 1− x Br 3 perovskites doped with Bi at concentrations of 0.0059, 0.0072, and 0.0120 were studied. The importance of high-quality materials for applications in optics and photonics was noted. 133 Cs NMR showed high sensitivity for studying these concentrations of Bi, which affect the stability of perovskites and their dynamic parameters.

Рассмотрены легированные соединения халькопирита. Приведены результаты изучения спектральных параметров методом ядерного магнитного резонанса 63,65 Cu в локальном поле, а также методом электронного парамагнитного резонанса в интервале температур 15-300 K. Наблюдаемое уширение резонансных линий спектров ядерного магнитного резонанса и обнаружение парамагнитного сигнала в образце при температуре 15 K свидетельствуют о появлении антиструктурных дефектов. Быстрое изменение формы линии спектра электронного парамагнитного резонанса в интервале температур 100-130 K связывается со структурно-фазовым переходом. Ключевые слова: термоэлектрики, соединения халькопирита, антиструктурные дефекты.

optoelectronic properties of indium and tin oxide thin films depending on the oxygen content in the total gas flow were experimentally investigated during deposition of these films by DC magnetron target sputtering. Relationship of the hetero junction thin-film solar cell output parameters vs. oxygen partial pressure in a vacuum vessel was examined during indium and tin oxide layer deposition. The maximum photovoltaic conversion efficiency of the solar cell was achieved at an oxygen partial pressure in the vacuum vessel of 6.5 Torr.

Doped chalcopyrite compounds are considered. The results of studying the spectral parameters by the 63,65Cu NMR method in a local field, as well as by the EPR method in the temperature range 15-300 K are presented. The observed broadening of the resonance lines of the NMR spectra and the detection of a paramagnetic signal in the sample at a temperature of 15 K indicate the appearance of anti-structural defects. The rapid change in the shape of the EPR spectrum line, in the temperature range 100-130 K, is associated with the structural-phase transition. Keywords: thermoelectrics, chalcopyrite compounds, antisite defects.

Chalcopyrite CuFeS2 is a known semiconductor mineral with a wide range of unique physical and chemical properties. These materials can be used as elements of solar batteries, coherent and incoherent sources of polarized radiation, in photovoltaic, thermoelectric and spintronic devices. Despite the relatively large number of studies on CuFeS2, many questions about its magnetic and electronic properties, are still outstanding. In this paper we were carried out studies of the distribution of the electron density and spin density in the nuclei of iron and copper in the semiconductor mineral CuFeS2. Special attention was devoted to interrelation of electronic and spin subsystems of the compound. The results of studies of the compound obtained in NMR 63,65Cu local field at low temperatures were used to perform the corresponding analysis. The cluster approach was used. The biggest cluster had Cu9Fe10S28-4 formula. Calculations were carried out in the framework of restricted self-consistent Hartree - Fock with open shells (SCF-LCAO-ROHF), MINI basis. The calculations were made with the “foundation” on the quadrupole parameters (quadrupole νQ frequency and the asymmetry parameter of the electric field gradient tensor η), obtained from the experiment. Study of electron density maps were performed for the regions containing chains of Fe-S-Cu and S-Fe-S for the different layers of metals and sulfur atoms. It is shown that the nature of the connection of iron atoms belonging to neighboring layers with sulfur atoms of the intermediate layer is different, which is reflected on the electron density distribution.

This paper presents the results of studies of new thermoelectric materials, obtained on the basis of multicomponent semiconductor compounds with a crystal structure of chalcopyrite and delafossite, by methods of nuclear magnetic resonance in a local field (63.65Cu NMR) and nuclear quadrupole resonance (63.65Cu NQR). The values of local magnetic fields at the location of the resonant copper nuclei and the parameters of nuclear quadrupole interactions in chalcopyrite (CuFeS2) and copper aluminate (CuAlO2) are determined. The search for new thermoelectric materials is caused by the low operating efficiency of industrial thermoelectric converters based on bismuth and lead tellurides, which have been used for half a century.

The 63Cu and 27Al NMR spectra have been obtained on a polycrystalline CuAlO2 sample in external magnetic field H0 = 92.8 kOe in temperature range 30–400 K. Analysis of the 27Al NMR spectra has revealed that with temperature decrease, the NMR line shift 27K increases in magnitude and can be described by the Curie–Weiss law. Such a behavior can be attributed to the emergence of an effective magnetic moment at copper ions due to the motion of holes in the copper sublattice. In the low-temperature range, the maximum of the spin–lattice relaxation rate $$T_{1}^{{ - 1}}$$ of 27Al nuclei is observed, which is most probably induced by thermally activated diffusion of holes. Analysis of experimental data on $$T_{1}^{{ - 1}}$$ yields an estimate Ea ≈ 0.1–0.2 eV for the activation energy. The temperature dependences of the quadrupole interaction parameters indicate the crystal lattice compression along the a and c axes.

63,65 Cu NMR study was carried out on a series of Cu 1–x Pd x FeS 2 compounds (x = 0–0.02) in a local magnetic field at 77 K. The spectra of the samples were taken. Their parameters were determined and the fields in the region of 63,65 Cu nuclei were estimated. Asymmetric broadening of the NMR resonance lines was found along with a smoother decay in the high-frequency region, which may result from an increase in the amount of defects in the crystal lattice of the compound. These can be FeCu 2+ antistructural defects, whose formation is attributed to the generation of the PdS phase in the chalcopyrite matrix with an increase in the nominal Pd content.

A Cu-63,Cu-65 NMR study was carried out on a series of Cu1-xPdxFeS2 compounds (x = 0-0.02) in a local magnetic field at 77 K. The spectra of the samples were taken. Their parameters were determined and the fields in the region of Cu-63,Cu-65 nuclei were estimated. Asymmetric broadening of the NMR resonance lines was found along with a smoother decay in the high-frequency region, which may result from an increase in the amount of defects in the crystal lattice of the compound. These can be FeCu2+ antistructural defects, whose formation is attributed to the generation of the PdS phase in the chalcopyrite matrix with an increase in the nominal Pd content.

Samples of a series of Cu 1–x Pd x FeS 2 (x = 0—0.02) compounds were studied by 63,65 Cu NMR in a local field at a temperature of 77 K. The spectra of the samples were measured, their parameters were determined, and the fields in the region of 63,65 Cu nuclei were estimated. An asymmetric broadening of the resonance NMR lines with a smoother decay in the high-frequency region was found, which may be the result of an increase in the number of defects in the crystal lattice of the compound. Such defects can be Fe Cu 2+ antisite defects, the formation of which is caused by the formation of the PdS phase in the chalcopyrite matrix with an increase in the nominal Pd content.

The 63,65Cu nuclear quadrupole resonance spectra and spin–lattice relaxation rate (1/T1) have been measured in the semiconductor compound CuAlO2. The value of the nuclei quadrupole interaction constant QCC = 56.24(6) MHz (T = 298 K) has been obtained. The broad maximum has been found in the temperature dependence of 1/T1 in the low-temperature region (below 276 K). This maximum can be associated with the presence of energy levels in the forbidden band. The activation energy has been estimated in CuAlO2 [EA = 45(2) meV], assuming the activation character of the mobility of holes.

Abstract Interaction of conical carbon nanotubes with lithium during their electrochemical treatment was studied by galvanostatic measurements. The presence of reversible and irreversible reactions during the Li insertion into conical carbon nanotubes was established. The structural changes occurring in the conical walls of the conical carbon nanotubes in consequence of the lithium intercalation were investigated by using X-ray diffraction. The results obtained show that the lithiation of conical carbon nanotubes is partially reversible and leads to a change in the diffraction peak profile (2θ = 26°) corresponding to the interplanar distance in conical carbon nanotubes. Such changes are associated with the lithium insertion into the interplanar spaces of conical carbon nanotubes.

AbstractThe results of studying natural samples of CuFeS_2 chalcopyrite mineral from hydrothermal ore manifestations of island arcs of the Pacific Ocean by ^63Cu nuclear magnetic resonance (^63Cu NMR) in a local field at room temperature are presented. The asymmetric shape of the detected resonance lines in the ^63Cu NMR spectrum indicates the presence of at least two overlapping lines. The presence of two overlapping central components can be a consequence of the occurrence of regions with different types of structural distortion near the resonant nuclei. These results show that the pulsed ^63Cu NMR method can be an effective method for studying the physical properties of deep-sea polymetallic sulfides of the global ocean.

The synthesized sample of covellite was investigated by NQR 63,65Cu methods. The experimentally determined values of the quadrupole frequency νQ and the asymmetry parameter η have been used to study the distribution of electron density in the region of the quadrupole nuclei in position Cu1. It is found that Cu-S bond in position Cu1 is ionic, and the gap LUMO-HOMO decreases with increasing temperature.

The results of studying natural samples of CuFeS 2 chalcopyrite mineral from hydrothermal ore manifestations of island arcs of the Pacific Ocean by 63 Cu nuclear magnetic resonance ( 63 Cu NMR) in a local field at room temperature are presented. The asymmetric shape of the detected resonance lines in the 63 Cu NMR spectrum indicates the presence of at least two overlapping lines. The presence of two overlapping central components can be a consequence of the occurrence of regions with different types of structural distortion near the resonant nuclei. These results show that the pulsed 63 Cu NMR method can be an effective method for studying the physical properties of deep-sea polymetallic sulfides of the global ocean.

The synthesized sample of covellite was investigated by NQR 63,65Cu methods. The experimentally determined values of the quadrupole frequency νQ and the asymmetry parameter η have been used to study the distribution of electron density in the region of the quadrupole nuclei in position Cu1. It is found that Cu-S bond in position Cu1 is ionic, and the gap LUMO-HOMO decreases with increasing temperature.

Представлены результаты исследования природных образцов минерала халькопирита CuFeS2 из массивных океанических сульфидных руд Срединно-Атлантического хребта методом ядерного магнитного резонанса 63Cu (ЯМР 63Cu) в локальном поле при комнатной температуре. Значительная ширина обнаруженных резонансных линий в спектре ЯМР 63Cu прямо свидетельствует о большом распределении локальных магнитных и электрических полей в исследованных образцах халькопирита. Это распределение может быть следствием заметного отклонения состава исследованных образцов халькопирита от стехиометрического. Полученные результаты показывают, что импульсный метод ЯМР 63Cu может быть одним из эффективных методов изучения физических свойств глубоководных полиметаллических сульфидов Мирового океана. DOI: 10.21883/FTP.2017.01.8253

The results of investigating natural samples of chalcopyrite mineral CuFeS2 from massive oceanic sulfide ores of the Mid-Atlantic ridge by the 63Cu nuclear magnetic resonance (NMR 63Cu) in a local field at room temperature are presented. The significant width of the resonance lines found in the 63Cu NMR spectrum directly testifies to a wide distribution of local magnetic and electric fields in the investigated chalcopyrite samples. This distribution can be the consequence of an appreciable deviation of the structure of the investigated chalcopyrite samples from the stoichiometric one. The obtained results show that the pulsed 63Cu NMR can be an efficient method for studying the physical properties of deep-water polymetallic sulfides of the World Ocean.