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The physical characteristics of stable formation of the limiting permissible thermo-electrodynamic states of superconductors with various types of nonlinearity in their current–voltage characteristics (CVC) are discussed. The analysis was based on describing the CVC using a model that assumes its continuous increase with varying degrees of smoothing (different intensities of increase at a fixed value of the critical current). A power-law equation was used to describe it. The results were compared with those from numerical experiments simulating thermo-electrodynamic states of superconductors with a zero-voltage subcritical region and an idealized CVC (nonsmoothed CVC), described by a piecewise continuous equation derived from the viscous flux-flow model. It is shown that an increase in the smoothing of the CVC of a superconductor, under otherwise equal conditions (at a fixed value of critical current density and cooling conditions), is accompanied by a decrease in its current-carrying capacity. Its degradation is caused by a corresponding increase in heat losses, which inevitably exist owing to the continuous increase in the CVC of the superconductor throughout the current injection process. As a consequence, the values of the limiting permissible currents stably flowing through the superconductor with a nonsmoothed CVC, under otherwise equal conditions, are higher than the corresponding values calculated for superconductors with a smoothed CVC. This feature is observed despite the different nature of current filling the cross section of the superconductor. It is proven that, for the correct determination of the current-carrying capacity of superconductors, the permissible values of temperature and electric field intensity preceding the onset of current instability cannot be predefined. They depend on the degree of smoothing of the CVC, the current injection rate, the transverse size of the superconductor, and the conditions of cooling. As a consequence, there is a nontrivial relationship between the maximum allowable losses and the maximum stable value of injected current. These features must be taken into account when experimentally measuring the CVCs of superconductors and their current-carrying capacity. [ABSTRACT FROM AUTHOR]

In this work, the optical and electronic characteristics of MoS2(n,n) and MoSe2(n,n) nanotubes and 1D van der Waals nanoheterostructures based on them are determined from first principles. It is shown that with an increase in the diameters of MoS2(n,n) and MoSe2(n,n) nanotubes, their bandgaps increase (in MoS2(n,n), the gap varies from 0.27 eV to 1.321 eV, and in MoSe2(n,n) from 0.153 eV to 1.216 eV). It was found that with an increase in the diameter of the nanotubes, the static permittivity decreases; van der Waals nanostructures of MoS2(8,8)@MoSe2(16,16) and MoS2(6,6)@MoSe2(14,14) consisting of coaxially compound MoS2(8,8) and MoSe2(16,16), MoS2(6,6) and MoSe2(14,14), respectively, have high static dielectric permittivitiesof 6. 5367 and 3.0756. Such nanoheterostructures offer potential for developing various nanoelectronic devices due to the possibility of effective interaction with an electric field. Studies revealed that the van der Waals nanostructures MoSe2(6,6)@MoS2(14,14) and MoSe2(8,8)@MoS2(16,16) exhibit a semiconductor nature with bandgap widths of 0.174 eV and 0.53 eV, respectively, and MoS2(6,6)@MoSe2(14,14) and MoS2(8,8)@MoSe2(16,16) exhibit metallic properties. Stepped areas of Coulomb origin with a constant period at a voltage of 0.448 V appear on the current–voltage characteristic of the van der Waals nanoheterodevices. It is found that MoSe2(6,6)@MoS2(14,14) and MoSe2(8,8)@MoS2(16,16) nanodevices transmit electric current preferentially in the forward direction due to the formation of a nanoheterojunction between semiconductor nanotubes with different forbidden band values. The fundamental regularities obtained during the study can be useful for the further development of electronic components of nano- and microelectronics. [ABSTRACT FROM AUTHOR]

4-probe measurements of surface resistivity, measurements of dark and light current-voltage characteristics, the possibilities of using a thin PdSi film to obtain perfect nano-sized ohmic contacts on the Si(111) surface have been investigated using Auger electron spectroscopy methods in combination with ion etching of the surface. It has been shown that the depth of Ni diffusion in the Ni-Si (111) system is 400 ‑ 500 Å at indoor temperature, and 70 – 80 Å in the Ni-PdSi-Si (111) system. The quality of the ohmic contact in the latter case does not change up to T = 800 K and withstands luminous flux illumination up to F = 1100 lux. It is shown that the resistivity of the PdSi film passes through a minimum at T = 900 – 1000 K. An analysis of the results obtained will be given in the article.

This paper presents calculations of the current-voltage, dI/dV- and d2I/dV2-characteristics for a Josephson junction with a short one-dimensional channel, taking into account a "deformed" (anomalous) energy-dependent Andreev reflection function. Depending on the degree of deviation from the classical Andreev reflection coefficient, the "anomalous" functions are conditionally divided into weakly and strongly deformed coefficients. The excess Andreev current decrease is demonstrated with increasing anomaly factor due to the low probability of multiple Andreev reflections compared to the classical case. It has been shown that anomalous fractional (fractal) gap structures arise in the spectra, which require experimental verification. The analysis shows that on the spectrum of modified dynamic conductivity, when considering the anomalous function of Andreev reflections, the second Andreev feature becomes more pronounced as a minimum and the first feature manifests as a notable kink, which is absent in the classical dependencies for cases of high transparency obtained within the Averin–Bardas model. In the anomalous mode, the Andreev features appear as "dips" in the relatively high-energy region, which have also been detected in the Josephson junction spectra, indicating the possibility of generating high-frequency phonons. [ABSTRACT FROM AUTHOR]

The properties of a metal contact with a p-GaAs layer ~8 nm thick induced by low-energy Ar+ ions on an n-GaAs wafer as a result of the conduction type conversion have been studied. The metal was deposited according to the standard technology on the surface of the semiconductor p-GaAs with a natural oxide layer partially restored when the sample was transferred to a deposition setup. To prevent metallization of the nanolayer the contact was not annealed. Therefore, a Schottky barrier emerged at the interface and a residual oxide layer retained. However, current–voltage characteristics showed that the formed contact is predominantly ohmic. It has been found that a high concentration of ion-induced defects radically reduces the width of the Schottky barrier and ensures the tunneling of holes and electrons of the semiconductor valence band through the barrier in the forward and reverse directions, respectively. It has been shown that ion bombardment of the p-GaAs semiconductor surface makes it possible to obtain an ohmic contact with any metal without annealing. It is concluded that the ion-stimulated modification of the semiconductor and the exclusion of annealing make it possible to obtain a tunnel ohmic contact with an extremely thin p-GaAs nanolayer coated with the residual layer of natural oxide. [ABSTRACT FROM AUTHOR]

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Josephson junctions based on superconducting materials are fundamental components for quantum detection, quantum communication and quantum computers. An accurate behavioral model of Josephson junctions is the prerequisite for predicting the response (or the behavior) of various superconducting circuits. In this study, we present a resistively and capacitively shunted junction model-based behavioral-level model for the current–voltage characteristics of Josephson junctions. This model accurately predicts the current–voltage characteristics and their temperature dependencies of Josephson junctions made of different materials under three typical working modes: underdamped voltage-driven, overdamped current-driven, and underdamped current-driven. Additionally, it forecasts the critical current and superconducting energy gap characteristics with respect to temperature, as well as the constraint relationship between the shunt resistance, superconducting energy gap, and critical current. Comparing the measured data with the simulation predictions, the model has an average accuracy of 89.28 % , which demonstrate its reliability. [ABSTRACT FROM AUTHOR]

Equivalent electrical circuits of multilayer film structures with memristor switching of resistance at interlayer boundaries and at the boundaries of crystal grains in each layer are proposed. Numerical modeling of the current-voltage characteristics of such structures has shown that their loop-shaped form, typical of memristors, is transformed into a linear ohmic dependence of the total current on the magnitude of the applied external voltage as both the number of layers and the number of grains in each layer increase. A certain combination of the number of layers and grains in a layer has been established, at which the maximum total current flowing through the structure and the ratio of resistances in the “off” and “on” states reach the highest values.

The effect of doping with holmium (Ho) and erbium (Er) rare-earth elements (REE) on the main parameters and characteristics of photocells based on p-GaSe/n-InSe heterostructures has been experimentally studied. Photo-electromotive force measurements were performed for undoped and rare-earth doped samples and obtained results comparatively analyzed. The light characteristic of the samples shows that significant improvement are observed in the rare-earth doped crystals. The possibility of targeted control, as well as increasing their reproducibility and stability by changing the content of the introduced impurity (NREE), is shown. The optimal situation is provided by alloying Er with NREE≈10−1 at.%. [ABSTRACT FROM AUTHOR]

The paper presents the results of a theoretical study of the electronic structure and electrical conductivity of single-walled gold nanotubes with chirality indices (4, 0), (5, 0), (6, 0), (7, 0), (4, 4), and (5, 5). The simulations were performed using the density functional theory and the method of nonequilibrium Green's functions. The Perduew–Burke–Ernzerhof exchange-correlation functional and a two-exponential basis set were used. The importance of using polarized basis sets for the study of electrical properties of gold nanotubes is demonstrated. Analysis of the results showed that the transmission functions of the studied nanotubes depend on their structure in a complex way but, in general, increase with increasing diameter. The dependence of the transmission function on the electron energy does not allow us to speak a priori about the linearity of the current–voltage characteristic of gold nanotubes within a certain finite voltage range. In addition to defect-free single-walled gold nanotubes, gold nanotubes of different diameters with a vacancy-type defect-were also studied. This allowed us to evaluate the effect of such a defect on the atomic structure and electrical conductivity of the single-walled gold nanotubes. It was demonstrated that the conductivity drop can vary within a wide range, correlating with changes in the atomic structure. [ABSTRACT FROM AUTHOR]

4-probe measurements of surface resistivity, measurements of dark and light current-voltage characteristics, the possibilities of using a thin PdSi film to obtain perfect nano-sized ohmic contacts on the Si(111) surface have been investigated using Auger electron spectroscopy methods in combination with ion etching of the surface. It has been shown that the depth of Ni diffusion in the Ni-Si (111) system is 400 - 500 Å at indoor temperature, and 70 – 80 Å in the Ni-PdSi-Si (111) system. The quality of the ohmic contact in the latter case does not change up to T = 800 K and withstands luminous flux illumination up to F = 1100 lux. It is shown that the resistivity of the PdSi film passes through a minimum at T = 900 – 1000 K. An analysis of the results obtained will be given in the article. [ABSTRACT FROM AUTHOR]

In the work the current-voltage characteristic (CVC) of photovoltaic modules (PVM) were measured by fast scanning them using an automated system developed by us on the Raspberry Pi microcomputer platform. A theoretical model and an algorithm for processing experimental data have been developed for the analysis of PVM parameters changes with voltage. The voltage dependences of the ideality factor of the pn junction, the reverse saturation current and their influence on the CVC have been clarified. Numerical determination of these parameters allows characterizing electrical losses and recombination processes in solar cells under various external conditions. It is shown that ideality factor can be significantly exceeds 2 in the voltage range less than the maximum power point. This is characteristic for PVM manufactured using modern technologies. The changes of the reverse saturation current and its growth in a certain voltage range due to significant recombination current were analyzed. [ABSTRACT FROM AUTHOR]

The current density–voltage characteristic (J–V) is a critical tool for understanding the behavior of solar cells. This study presents an overview of the key aspects of J–V analysis and introduces a user‐friendly flowchart that facilitates the swift identification of the most probable limiting process in a solar cell, based mainly on the outcomes of light‐intensity‐dependent J–V measurements. The flowchart is developed through extensive drift‐diffusion simulations and a rigorous review of the literature, with a specific focus on perovskite and organic solar cells. Moreover, the flowchart proposes supplementary experiments that can be conducted to obtain a more precise prediction of the primary performance losses. It therefore serves as an optimal starting point to analyse performance losses of solar cells. [ABSTRACT FROM AUTHOR]

Novel dye brilliant green (BG) based devices are fabricated using a low–cost spin coating process on a p–type silicon substrate. The front gold contact is deposited onto the BG film at a high vacuum. The current–voltage measurements in the dark and under various light intensities at room temperature are performed. Experimental data are exploited, and electrical parameters are extracted to describe a non–ideal diode behavior of the BG–based device. The Cheung and Norde approximations and thermionic emission theory are utilized to extract the suitable electrical parameters, including ideality factor (n), barrier height (Φb), series resistance (RS), open-circuit voltage (VOC), short circuit current (ISC), and interface state density (Dit). The capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics of Au/BG/p–Si/Alheterostructure are described in the dark and room temperature. Furthermore, the influence of the resistance series and the interface states on the operation of the diodes in the dark and illumination modes is also emphasized. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the characteristics of the junction between the titanium down conductor of a thin-film solid-state lithium-ion battery (a-Si) and a negative Si@O@Al nanocomposite electrode. The results of measuring the band gap of the Si@O@Al nanocomposite and the height of the Schottky barrier of the Ti–Si@O@Al junction are presented. The transmission and reflection spectra of Si@O@Al films and its main phases a-Si, a-SiOx, and a-Si(Alx) are studied. The band gap of Si@O@Al was determined by the Tauc method, which is 1.52 eV for a-Si and 1.15 eV for nc-Si. The IV characteristics of Ti‒Si@O@Al, Ti–a-Si, Ti–a-SiO0.8, and Ti–a-Si0.9(Al0.1) structures have been studied and the height of the Schottky barrier has been determined. The results obtained make it possible to estimate the Fermi energy of the nanocomposite and to interpret the hike in the SSLIB charging voltage as a result of the Al acceptor impurity compensation during lithiation. A change in the majority charge carriers in Si@O@Al leads to a decrease in the hole current and an increase in the density of the over-barrier electron current, as a result of which a step with a height of 1.5 V is formed on the charging curve. [ABSTRACT FROM AUTHOR]

Abstract Graphene Nano Scrolls (GNSs) and Zigzag graphene nanoscrolls (ZGNSs) are semi-one-dimensional materials with exceptional electrical and optical properties, making them attractive to be used in nanoelectronics and complementary metal–oxide–semiconductor (CMOS) technology. With in CMOS device technology, time delay is a crucial issue in the design and implementation of CMOS based ZGNSs. Current paper focus is on ZGNSs application in the channel area of metal–oxide–semiconductor field-effect transistors (MOSFETs) in CMOS technology. We studied analytically, the importance of different parameters on time delay reduction, resulting in faster switching and higher frequency in integrated circuits (ICs). The results of this research demonstrates that, the ZGNS-based CMOS proves considerable variations in the current due to the geometrical parameters, such as chirality number, channel length, and nanoscroll length which can be engineered to produce faster ICs.

In this work, the optical and electronic characteristics of MoS2(n,n) and MoSe2(n,n) nanotubes and 1D van der Waals nanoheterostructures based on them are determined from first principles. It is shown that with an increase in the diameters of MoS2(n,n) and MoSe2(n,n) nanotubes, their bandgaps increase (in MoS2(n,n), the gap varies from 0.27 eV to 1.321 eV, and in MoSe2(n,n) from 0.153 eV to 1.216 eV). It was found that with an increase in the diameter of the nanotubes, the static permittivity decreases; van der Waals nanostructures of MoS2(8,8)@MoSe2(16,16) and MoS2(6,6)@MoSe2(14,14) consisting of coaxially compound MoS2(8,8) and MoSe2(16,16), MoS2(6,6) and MoSe2(14,14), respectively, have high static dielectric permittivitiesof 6. 5367 and 3.0756. Such nanoheterostructures offer potential for developing various nanoelectronic devices due to the possibility of effective interaction with an electric field. Studies revealed that the van der Waals nanostructures MoSe2(6,6)@MoS2(14,14) and MoSe2(8,8)@MoS2(16,16) exhibit a semiconductor nature with bandgap widths of 0.174 eV and 0.53 eV, respectively, and MoS2(6,6)@MoSe2(14,14) and MoS2(8,8)@MoSe2(16,16) exhibit metallic properties. Stepped areas of Coulomb origin with a constant period at a voltage of 0.448 V appear on the current–voltage characteristic of the van der Waals nanoheterodevices. It is found that MoSe2(6,6)@MoS2(14,14) and MoSe2(8,8)@MoS2(16,16) nanodevices transmit electric current preferentially in the forward direction due to the formation of a nanoheterojunction between semiconductor nanotubes with different forbidden band values. The fundamental regularities obtained during the study can be useful for the further development of electronic components of nano- and microelectronics.

We report calculations of current‒voltage characteristics (I‒V characteristics) of Josephson junctions using the resistive model. The I‒V characteristics are found to be stable to deviations of the dependence of the superconducting current on the phase difference (φ) of the order parameter at the junction boundaries from the simple sinusoidal one, characteristic of ideal Josephson junctions. It is shown that to analyze the processes occurring in Josephson junctions, it is important to measure the spectral composition of generation from these junctions. [ABSTRACT FROM AUTHOR]

The effect of pulsed laser radiation on the change in the parameters of semiconductor structures of field-effect transistors with a Schottky gate with an operating frequency range of 1.5–8 GHz and integrated amplifiers with an operating frequency range of 0.4–6 GHz is studied. Laser radiation with 25 ns pulse duration, incident on the transistor crystal, creates a pulsed photo current. It is shown that the amplitude of the pulsed photo current is three times higher than the operating transistor current. The current-voltage characteristics of the field-effect transistor were measured in the mode of pulsed laser radiation. The amplitude dependence of the pulsed photocurrent in semiconductor structures on the power of laser radiation for various wavelengths of 1.06 and 0.53 μm is studied. It is shown that as a result of the action of pulsed laser radiation on semiconductor structures, a short disappearance of the amplification of the high-frequency signal at the amplifier output occurs. [ABSTRACT FROM AUTHOR]

This study focuses on the modification of ion-exchange membranes by incorporating a phosphorylated dendrimer into sulfonated polytetrafluoroethylene membranes to enhance the specific selectivity between mono-/divalent ions, using the Ca2+/Na+ pair as an example. This research employs mechanical, physicochemical, and electrochemical analyses to explore the effects of P-H20 incorporation on membrane properties. Bulk modification significantly increases membrane selectivity towards calcium ions (the specific permselectivity coefficient rises from 1.5 to 7.2), while maintaining the same level of the limiting current density. Other findings indicate that bulk modification significantly changes the transport-channel structure of the membrane and alters the mechanism of over-limiting mass transfer. The over-limiting current for the pristine membrane is mainly due to non-equilibrium electroconvection, while modified membranes actively participate in the water-splitting reaction, leading to the suppression of the electroconvection. Despite this drawback, the decrease of the over-limiting potential drop results in a decrease in specific energy consumption from 0.11 to 0.07 kWh/mol. In the underlimiting current mode, the specific energy consumption for all studied membranes remains within the same limits of 0.02–0.03 kWh/mol. [ABSTRACT FROM AUTHOR]

This study focuses on the modification of ion-exchange membranes by incorporating a phosphorylated dendrimer into sulfonated polytetrafluoroethylene membranes to enhance the specific selectivity between mono-/divalent ions, using the Ca2+/Na+ pair as an example. This research employs mechanical, physicochemical, and electrochemical analyses to explore the effects of P-H20 incorporation on membrane properties. Bulk modification significantly increases membrane selectivity towards calcium ions (the specific permselectivity coefficient rises from 1.5 to 7.2), while maintaining the same level of the limiting current density. Other findings indicate that bulk modification significantly changes the transport-channel structure of the membrane and alters the mechanism of over-limiting mass transfer. The over-limiting current for the pristine membrane is mainly due to non-equilibrium electroconvection, while modified membranes actively participate in the water-splitting reaction, leading to the suppression of the electroconvection. Despite this drawback, the decrease of the over-limiting potential drop results in a decrease in specific energy consumption from 0.11 to 0.07 kWh/mol. In the underlimiting current mode, the specific energy consumption for all studied membranes remains within the same limits of 0.02–0.03 kWh/mol.

Introduction. The general system of parameters, including compression points and intersection points of various harmonics, is unsuitable for devices operating under the influence of baseband pulses (for example, before the modulator in the transmitter, after the demodulator in the receiver). Previously, the authors have developed simple models in the form of nonlinear recursive filters, which give a satisfactory error in describing the response of a wide class of baseband pulse circuits. The system of nonlinear functions of such models can be considered as a new system of characteristics of nonlinear-dynamical baseband impulse circuits, for which it is necessary to develop a method that ensures their measurement with an acceptable error. In the general formulation, this problem is rather challenging; therefore, this article considers only a first-order nonlinear recursive filter. However, the obtained result gives satisfactory results for devices without flat top transient overshoot.Aim. To consider a method for measuring the characteristics of nonlinear-dynamical baseband impulse devices without overshoot on the flat top of the transient response.Materials and methods. The considered recursive filter is represented by an equivalent circuit consist of nonlinear resistive and capacitive elements. Therefore, the task is reduced to measuring their current-voltage characteristics (IV) and charge-voltage characteristics (CVC). IV characteristics are measured at the flat tops of the transient characteristics of the device. Having a certain IV, we obtain the opportunity to calculate the current (and then the charge) of the capacitive element. The experimental study was carried out on the example of a three-stage amplifier with an aperiodic transient response.Results. The transient characteristics of the filter are approximated by the model with an accuracy of no worse than 3.2 %.Conclusion. The considered system of functions can be obtained with a definable error that satisfactory for practice, which allows it to be considered as a new system of parameters for nonlinear baseband pulse devices.

This article presents experimental results on the study of the current-voltage characteristics of strongly compensated n- and p-type silicon samples diffusion-doped with zinc at a temperature of 80 K. The current-voltage characteristics of the studied samples contain both sublinear and superlinear sections. Several (up to eight) characteristic areas were found, the number of which depends on the degree of illumination, temperature, and electrical resistivity of the sample. Under certain conditions, there is an alternation of sections of the current-voltage characteristic with negative differential conductivity of the N- and S-type, behind which current instabilities with an infra-low frequency are observed. The appearance of sections of the current-voltage characteristic with a quadratic dependence is explained by the presence of fast and slow recombination centers associated with zinc nanoclusters, and sublinear sections are explained in terms of the theory of the "injection depletion effect". The formation of nanoclusters with the participation of zinc ions was confirmed by atomic force microscopy studies.

In the paper, the effects of type, dose and temperature of irradiation with stable elementary particles (0.9 MeV electrons and 15 MeV protons) on the properties of the high-voltage 4H-SiC Junction Barrier Schottky diodes at room temperature (23°С) and the limiting operating one (175°С) have been compared. The electron irradiation of the objects with equal doses at 23°С и 175°С was found to cause a significant increase in its base differential resistance in the former case and the absence of this effect in the latter. However, in the latter, DLTS spectra exhibited a noticeable increase in the concentration of deep levels in the upper half of the band gap. The proton irradiation resulted in a noticeable rise in the mentioned resistance even at 175°С. The results obtained make it possible to evaluate the radiation resistance of the studied devices to proton and electron irradiation within the framework of any given requirements.

The possibility of estimating the ionization parameters of high-temperature gas mixtures formed as a result of combustion processes is considered on the basis of the current–voltage characteristics measured using electrodes that generate an external electric field in the media under consideration. [ABSTRACT FROM AUTHOR]

A comprehensive study was performed for the design of ABX3 perovskites, (A = Li, K, Na, B = Ge, Sn, Pb, X = F, Cl, Br, I) and organic hole transfer materials, HTMs (Fu‐2a, Fu‐2b, Fu‐2c, and Dm‐Q) for efficient perovskite solar cells (PSCs) through quantum chemistry calculations. Photovoltaic characteristics of the investigated perovskites are strongly affected by the halide anions. The results reveal that reducing the exciton binding energy of perovskites enhances the rate of the formation/dissociation of holes and electrons so F‐based perovskites are superior from this viewpoint. Additionally, the electron and hole injection processes are more favorable in the case of the F‐based perovskites in comparison with other studied perovskites. Moreover, spectroscopic properties of the perovskites demonstrate that KSnCl3, NaSnCl3, and F‐based perovskites exhibit a greater ability of the light‐harvesting and incident photon to current conversion efficiency. Ultimately, based on diverse analyses, F‐based perovskites, KSnCl3 and NaSnCl3 are the preferred candidates to be applied in the PSCs due to an excellent incident photon to current conversion efficiency, light‐harvesting efficiency, short circuit current, and solar cell final efficiency. [ABSTRACT FROM AUTHOR]

Radiation degradation of Si ion detectors becomes critical for the experiments at new facilities giving the beam intensity increase up to 105 times. The study is focused on the impact of heavily damaged Bragg peak region (BPR) at the ion range end on the bulk current of Si sensors irradiated with 53.4 MeV 40Ar ions in the fluence range (1–4) × 109 ion/cm2. It is shown that taking into account only the generation current component is insufficient to explain the experimental I–V curves. Simulating I–V characteristics and the electric field profiles demonstrated arising of a built-in junction in the BPR, which controls hole diffusion at voltages below full depletion voltage. Contribution of this component to the total diode current enabled the agreement between experimental and simulated I–V curves. [ABSTRACT FROM AUTHOR]

A spectrometer based on silicon nanosandwiches has been proposed to detect complications caused by COVID-19. Operating in the mode of a balanced photodetector, the silicon nanosandwich is both a source of terahertz irradiation and a receiver of reflected and/or radiated from biological tissue. It has been demonstrated that recording the current–voltage characteristics of a silicon nanosandwich made it possible to analyze changes in the thyroid gland, thereby determining the degree and nature of changes caused by the COVID-19 disease. [ABSTRACT FROM AUTHOR]

Possible macroscopic mechanisms for the destruction of the superconducting properties of a high-temperature YBa2Cu3O7-based superconductor cooled with liquid helium or nitrogen under input of AC are analyzed. It is shown that these mechanisms can be both of thermal and thermoelectrodynamic nature, which is based on the interrelated change in the electromagnetic field induced inside the superconductor and its temperature. Before the emergence of unstable states, intense stable energy dissipation can be observed, which is not taken into account in the current theory of losses. These mechanisms lead to stable supercritical values of the introduced current and the electric field induced inside the superconductor before the onset of instability and, consequently, high permissible overheating. The results discussed expand the scope of practical use of high-temperature superconductors. [ABSTRACT FROM AUTHOR]

This article discusses characteristic features of energy dissipation from the eigenfield of transport current upon its stable penetration into a technical superconductor. The regimes of partial and complete penetration are considered. Analysis of dissipative states of a superconductor is compared with the results following from the theory based on the critical state model. It is demonstrated that the critical state model, according to which there is no electric voltage in superconductors at currents lower than critical one, underestimates heat release from the eigenfield of transport current and does not allow calculating correctly the energy losses in superconductors with actual current–voltage characteristics in the range of subcritical currents that can exist upon complete current penetration into superconductor. The error of the critical state model depends on the pattern of increase in current–voltage characteristic, the rate of current input, the transverse size of superconductor, and the critical current density. At the same time the self-similar and the zero-dimensional approximations make it possible to determine the energy losses in superconductors with actual current–voltage characteristic from varying eigenfield of transport current with sufficient accuracy upon both its partial and complete penetration. [ABSTRACT FROM AUTHOR]

Diodes are widely used in engineering. Therefore, it is very important to study the sensitivity of the characteristics to external influences. In this work, the influence of a magnetic field on the current-voltage characteristics (CVC) of a diode with a p-n junction is studied. Under the action of a magnetic field, the CVC of the diode, obtained in the experiments, shifted to the right. Under the action of a magnetic field, a decrease in current was observed even at high voltages. The theoretical foundations of this physical process have not been described in previous works. We explained these processes by the following reasons: the appearance of additional resistance at the p–n junction due to the magnetoresistance effect. As a result, the resistance of the diode increases, and the current also changes as a result of the Hall effect. The Lorentz force in a magnetic field affects the direction of movement of charge carriers in a space charge. This causes a change in the shape of the space charge and an increase in the potential barrier. These theoretical foundations were calculated from formulas and compared with experiments. In addition, changes in CVC in a magnetic field are also related to the coefficient of imperfection. The coefficient of imperfection depends on the diffusion length. The magnetic field affects the diffusion length. As a result, we explain the changes in CVC depending on the diffusion length by the nonideality coefficient. The change in the space charge of the diode under the action of a magnetic field can be explained by the Hall voltage, and the change in CVC can be explained by the magnetoresistance and the nonideality coefficient. Theoretical foundations are compared with experimental results and correspondences are determined. Conclusions are drawn from the compatibility of experience and our theoretical basis.

Experimental results are reported for a medium-wavelength infrared (MWIR) HgCdTe photodetector designed in a joint laboratory run by VIGO Photonics S.A. and the Military University of Technology. The parameters of the MWIR detectors fabricated with HgCdTe heterostructures were studied. Advances in the metal–organic chemical vapor deposition (MOCVD) technique enable the growth of HgCdTe epilayers with a wide range of composition and doping, used for uncooled infrared detectors. Device-quality HgCdTe heterostructures were deposited on 2-inch-diameter, low-cost (100) GaAs substrates. The heterostructures obtained were examined measuring the spectral response and current–voltage characteristics in different temperatures. Our intention here was to determine the relationship between electrical and optical results, using thermal analysis of dark current properties and photocurrent and spectral characteristics. The appearance of an additional signal source in certain ranges of reverse voltages was examined. Comparative analysis of the electrical and electro-optical characterization enabled us to isolate the photocurrent originating from different layers of the detector structure. Automated measurement techniques make it possible to correlate current responsivity with current–voltage curves measured as a function of temperature in a range from 10 K to 300 K with ±0.05 K resolution without human exertion. LabVIEW-aided data acquisition enables the averaging of each characteristic several hundred times, eliminates random and human errors, and decreases measurement uncertainty. [ABSTRACT FROM AUTHOR]

The results of an experimental study of the surface morphology of zinc-oxide films and the electrical properties of structures based on a single-crystal Si/microcrystalline ZnO heterojunction are presented. An analysis of the structure of the zinc-oxide films grown in argon and oxygen atmospheres is carried out, and the size distribution of nanofibers grown on its surface is obtained. The capacitance–voltage characteristics of In/ZnO/n-Si/Al and Au/ZnO/n-Si/Al heterostructures are simulated. On the basis of calculations and comparison of the experimental and simulated dependences, the concentration of free charge carriers in the sample and the position of the Fermi level are determined, the presence of a fixed charge in the system is revealed, and the density of surface states is found based on the ratio of the voltage applied to the system and the surface potential at the interface between layers. The value of the built-in surface charge is calculated. The relationship between the material of the upper contacts and the capacitance–voltage and current–voltage characteristics of the system is studied. The resistance of the formed zinc-oxide films is calculated. The prevailing charge-transfer mechanisms are discussed. An empirical dependence of the surface potential of silicon on the voltage applied to the structure is revealed. The effect of technological modes for obtaining zinc-oxide films synthesized by spray pyrolysis on the surface structure, effective capacitance of the structure, density of electronic states, and processes of charge-carrier transfer in samples under the action of an electric field is analyzed. [ABSTRACT FROM AUTHOR]

We analyze the characteristics of semiconductor emitters based on separate-confinement double heterostructures with quantum wells with different configurations of waveguide layers. Lasers with narrow and broad waveguides are considered as applied to the problem of increasing the output power. Semiconductor emitters with undoped and doped waveguide layers are compared. We consider lasers with ultranarrow and broad strongly asymmetric waveguides. It is shown that the reduction of series and thermal resistance reduces the self-heating of lasers and increases the output power and efficiency. The prospects of using the epitaxial integration for designing lasers with several tunnel-coupled emitting sections for increasing the output power and luminosity are considered. The possibility of constructing monolith-integrated thyristor lasers combining the emitting section and an electron switch in a single crystal is demonstrated. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article analyzes various methods and installations for heat removal from the surface of solar photovoltaic modules (PVMs). The distribution of solar energy in a PVM is theoretically substantiated. A cooler has been developed, consisting of a body and two fittings through which the coolant flows. Experimentally, an increase in the efficiency of solar PVMs by 9.3% using the developed cooler was revealed, and it was proven that the use of such solar photovoltaic stations near pumping stations gives an increase in efficiency. [ABSTRACT FROM AUTHOR]

The paper presents ways to improve the morphology and efficiency of perovskite solar cells synthesized from lead acetate trihydrate and methylammonium iodide. It was found that the quality of nanoscale films of the perovskite absorber depends on the time of precursor solution spinning and conditioning before annealing. The optimal combination of these times made it possible to increase the conversion coefficient and short-circuit current of perovskite solar cells to 10.97% and 18.7 mA/cm2, respectively. The results can be used to optimize the optoelectronic characteristics of perovskite depending on a number of kinetic parameters, such as the rotation speed, the acceleration time (acceleration) of the spin-coater, the temperature, and duration of annealing during the formation of solar cells. [ABSTRACT FROM AUTHOR]

The manufacturing technology and the results of measurements of current–voltage characteristics of ITO/SnO2/CdS/CdTe/Ag thin-film solar cells both without antireflection coating and with antireflection coating are presented. The material for the antireflection coating was obtained by melting the composition of MgF2 : CaF2 fluorides in a solar furnace at a component ratio of 55 : 45 (wt %). It is shown that the deposition of an antireflection coating on the outer surface of thin layer solar cells increased their efficiency to ~2.0%. [ABSTRACT FROM AUTHOR]

Copyright of Renewable Energy / Vidnovluvana Energetyka is the property of Institute of Renewable Energy of NAS of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plasma cleaning with simultaneous polishing by a jet electric discharge is more efficient than electrochemical polishing. The paper discusses the processes arising during the interaction of an electric discharge with solutions of inorganic substances, and studies the propagation of an inorganic discharge in a liquid on the surface of various materials (NaCl, NH4NO3, and discharge in glycerol). A NH4NO3 solution is shown to be the most effective electrolyte. We report on current‒voltage characteristics obtained for an electric discharge between a jet electrolytic cathode and a solid anode, as well as for a multichannel discharge in a jet electrolytic cathode at different jet lengths and diameters. [ABSTRACT FROM AUTHOR]

The study is devoted to an experimental analysis of the electrical and photoelectric characteristics of barrier photosensitive structures in the NBνN configuration based on n-HgCdTe. Seven different types of photosensitive structures for MWIR and LWIR infrared ranges, grown by molecular beam epitaxy, have been studied. The current–voltage characteristics were measured both in the dark and under illumination. The parameters of the NBνN structure, which realizes the maximum values of the photocurrent and the minimum values of dark currents in the operating range of bias voltages V for elevated operating temperatures, are determined. [ABSTRACT FROM AUTHOR]

The simulation of the photoluminescence and dark current-voltage characteristics of heterostructures with a single layer of quantum dots. The presence of the peak quantum transitions in the main points at 1,2 eV (modeling) and 1,12 eV (experimental). The experimental peak has a greater width (0,13 eV) at half maximum fundamental radiation transitions in quantum dots, compared to the modeled (0,06 eV). There is a shift of the experimental peak to longer wavelengths by about 65 meV, indicating that the presence in the dispersion structure the size of quantum dots. The dark current-voltage simulated characteristic at a temperature of 90 K and zero bias shows the value of the dark current density of 10-7 A/cm2, which is much smaller than the measurement results (10-6 A/cm2). There is a difference in the nature of the distribution depending on when the negative and positive displacement between experiment and simulation results associated with the presence of quantum dots larger.

Simulation of dependencies of characteristics of AlGaAs based solar cell, using AFORS-HET program, on thickness d and doping level NA base has been performed. It is found that increasing the thickness of the base from 1 to 10 microns leads to a dramatic increase in efficiency with 9,42 % at 1 microns to 33,03 % at 10 microns. Open circuit voltage Uoc, by increasing the thickness of the base from 1 to 50 microns increased by 95 mV. Increasing the doping level of the base leads to an increase short circuit current from 13,91 to 23,34 mA/cm2. The open circuit voltage will be increased from 1.487 to 1.594 V.