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Four types of barrier detectors based on a type II InAs/InAsSb superlattice with a wide-gap barrier made of a solid AlInAsSb lattice matched to the GaSb buffer were compared. The tested detectors differed in the type of doping of the active layer and the level and type of doping of the contact layer at the barrier. The epitaxial layers were deposited on GaAs (100) substrates using the molecular beam epitaxy method. The spectral and current–voltage characteristics of the analyzed detectors were compared. The highest current responsivities were observed in the structure with a p-type absorber (p+BpN+). Detectors with an n-type absorber (p+Bnn+, n+Bnn+, and nBnn+) show an increase in the current responsivity with an increase in the reverse bias voltage due to the reduction in the undesirable barrier in the valence band. Arrhenius characteristics for the dark current show that only in nBnn+ detectors, it was possible to limit the generation–recombination current. These detectors at 150 K were characterized by the highest normalized detectivity of approximately 3 × 1011 cm · Hz1/2/W. The obtained results were compared with literature data, showing that the parameters of type II superlattice photodetectors are close to those of HgCdTe photodiodes according to the "Rule 07" and "Rule 22" principles. [ABSTRACT FROM AUTHOR]

The time-dependent quantum transportation through a metal/polymer/metal system is theoretically investigated on the basis of a Su–Schrieffer–Heeger model combined with the hierarchical equations of motion formalism. Using a non-adiabatic dynamical method, the evolution of the electron subspace and lattice atoms with time can be obtained. It is found that the calculated transient currents vary with time and reach stable values after a response time under the bias voltages. However, the stable current as the system reaches its dynamical steady state exhibits a discrepancy between two sweep directions of the bias voltage, which results in pronounced electrical hysteresis loops in the current–voltage curve. By analyzing the evolution of instantaneous energy eigenstates, the occupation number of the instantaneous eigenstates, and the lattice of the polymer, we show that the formation of excitons and the delay of their annihilation are responsible for the hysteretic current–voltage characteristics, where electron–phonon interactions play the key factor. Furthermore, the hysteresis width and amplitude can also be modulated by the strength of the electron–phonon coupling, level-width broadening function, and temperature. We hope these results about past condition-dependent switching performance at a sweep voltage can provide further insight into some of the basic issues of interest in hysteresis processes in conducting polymers. [ABSTRACT FROM AUTHOR]

The deviations of cryogenic collector current–voltage characteristics of SiGe heterojunction bipolar transistors (HBTs) from ideal drift-diffusion theory have been a topic of investigation for many years. Recent work indicates that direct tunneling across the base contributes to the non-ideal current in highly scaled devices. However, cryogenic discrepancies have been observed even in older-generation devices for which direct tunneling is negligible, suggesting that another mechanism may also contribute. Although similar non-ideal current–voltage characteristics have been observed in Schottky junctions and were attributed to a spatially inhomogeneous junction potential, this explanation has not been considered for SiGe HBTs. Here, we experimentally investigate this hypothesis by characterizing the collector current ideality factor and built-in potential of a SiGe HBT vs temperature using a cryogenic probe station. The temperature dependence of the ideality factor and the relation between the built-in potential as measured by capacitance–voltage and current–voltage characteristics are in good qualitative agreement with the predictions of a theory of electrical transport across a spatially inhomogeneous junction. These observations suggest that inhomogeneities in the base–emitter junction potential may contribute to the cryogenic non-idealities. This work helps to identify the physical mechanisms limiting the cryogenic microwave noise performance of SiGe HBTs. [ABSTRACT FROM AUTHOR]

This paper presents a novel physics-based analytical model for the injection recombination current in micro-light emitting diodes (μLEDs) with multiple quantum wells (MQWs), specifically excluding trap-assisted tunneling contributions at low forward voltages. The model simplifies the complex MQW structure by representing MQWs as a single equivalent quantum well (EQW). The μLED current is attributed to the recombination of injected holes and electrons within this EQW. Key parameters of the model encompass the EQW's position within the depletion region, hole diffusion coefficient, series resistance, and thermal resistance of the device. Experimental validation of the model is performed using current–voltage characteristics obtained from InGaN/GaN QW μLEDs. [ABSTRACT FROM AUTHOR]

The sliding contact between a metal or semiconductor with another semiconductor can lead to a new charge generation mechanism known as the tribovoltaic effect. This effect has several advantage over the more common triboelectric effect, such as a higher rate of charge transfer and the ability to produce a direct current (DC) output directly via the junction interface. During operation, the junction interface produces a built-in electric field. In this study, we investigate the tribovoltaic effect on sliding between copper and unpoled lead zirconate titanate (PZT) ceramic. It was found that the contact between the metal and semiconducting oxide ceramic leads to the Schottky junction effect, which can effectively drive frictionally excited charges to an external load. By increasing the applied stress to PZT, we observed different current-voltage characteristic curves. The proposed electronic band behavior determines the electrical output direction in the tribovoltaic nanogenerator (TVNG). This direction depends on the built-in electric fields formed at the junction. The performance of the TVNG was tested in both series and parallel connections, observing clearly improved electrical outputs for both. The proposed TVNG can efficiently power small electronic devices, such as LEDs, and charge capacitors in a short period of time. This work expands the understanding of unconventional transport mechanisms through the Schottky contact of PZT and metal, and provides fundamental knowledge for the future development of tribovoltaic devices. [ABSTRACT FROM AUTHOR]

We introduce the notion of nonreciprocal superconductors where inversion and time-reversal symmetries are broken, giving rise to an asymmetric energy dispersion. We demonstrate that nonreciprocal superconductivity can be detected by Andreev reflection. In particular, a transparent junction between a normal metal and a nonreciprocal superconductor generally exhibits an asymmetric current-voltage characteristic, which serves as a defining feature of nonreciprocal superconductivity. Unlike the superconducting diode effects, our detection scheme has the advantage of avoiding large critical currents that turn the superconducting state to normal. Last, we discuss candidates for nonreciprocal superconductivity, including graphene, UTe2, as well as engineered platforms. [ABSTRACT FROM AUTHOR]

The ZrO2–HfO2 oxide films are prepared by pulsed chemical vapor deposition using volatile organometallic precursors. It is shown that the morphology, thickness, and uniformity of the resulting coatings are affected by the mode of reaction space organization. A 360 nm thick oxide coating is obtained by introducing the precursor vapor and the reactant gas into the reactor through an earlier elaborated system of separate reaction components supply. The atomic force microscopy data show that the resulting surface is almost smooth and has an arithmetic average roughness of a few nanometers. Current-voltage and capacitance-voltage characteristics of the obtained ZrO2–HfO2 oxide coatings are studied. It is noted that the breakdown electric field is almost independent of the oxide coating thickness (0.1-0.48 MV/cm) in the interval of 225-325 nm. The breakdown electric field increases as the oxide film thickness increases from 325 nm to 360 nm. The dependence of the dielectric constant on the oxide film thickness is determined from the measured capacitance-voltage characteristics of the obtained ZrO2–HfO2 films. It is shown that this dependence depends linearly on the film thickness. [ABSTRACT FROM AUTHOR]

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]

We investigate role of ATP sensitive potassium (KATP) channel in cytotoxic effect of cypermethrin on rat aortic smooth muscle cells. Cytotoxicity analysis was performed at 0, 0.1, 0.5, 10, 50, and 100 µM concentrations of cypermethrin and the cell index (CI) was calculated. KATP currents were recorded using patch clamp technique for 50 and 100 µM concentrations and channel conductivity was determined by obtaining current-voltage characteristics. No cytotoxic effect was observed in the first 72 hours. At the 96th hour, only at 100 µM concentration, the CI value decreased significantly compared to control group and at 120 and 144th hours, it was observed that the CI value decreased significantly at all concentrations. Currents and conductivities were significantly decreased at 50 and 100 µM concentrations. Results gave clues that cypermethrin causes a cytotoxic effect on vascular smooth muscles and that KATP channels may have a role in the emergence of this effect. [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.)

First-principles calculations were carried out to investigate the stability of two dimensional (2D) MB2 monolayers (TiB2-I, VB2-I, MnB2-I, TiB2-II, ScB2-II, NiB2-II) with an inverse sandwich configuration and their potential as efficient gas sensors to detect toxic gas molecules. We first identified six stable 2D MB2 configurations, based on stability evaluation covering thermodynamical, dynamical, and thermal aspects. To investigate the performance of these novel structures as gas sensors, the adsorption behavior of five toxic gas molecules (CO, NO, NO2, NH3, SO2) on MB2 has been explored, and the charge transfer and magnetic changes of these adsorption systems were analyzed. It is found that five gases are all chemisorbed on 2D MB2. Particularly, when CO is adsorbed on TiB2-II, the magnetism of the system undergoes a significant change from non-magnetism to antiferromagnetism, showing selectivity for CO. Furthermore, the current−voltage characteristics obtained from simulations confirm gas sensing performance. The TiB2-II is expected to be a candidate material for CO gas sensor with short recovery time (7.50 × 10−10 s). Our theoretical study provides new ideas for designing gas sensor nanomaterials with magnetism alteration as the indicator featuring easy measurement and fast response. [ABSTRACT FROM AUTHOR]

Bio‐based flexible dielectric substrates have gained tremendous attention for their potential to reduce environmental risks from nonbiodegradable electronic waste. The present study demonstrates the fabrication of facile, nontoxic, and biodegradable chitosan‐based flexible dielectric substrate using graphene nanoplatelet (GNP) as a nanofiller. The detailed impact of different concentrations of GNP (1, 2, and 3 wt%) into the chitosan (CS) matrix was studied on physicochemical, morphological, mechanical, electrical, and thermal properties. The fabricated CS/GNP composites showed improved mechanical strength, thermal stability, and electrical properties compared with unmodified CS film. The composites exhibited excellent thermal stability (200°C) with a promising biodegradation rate (within 6 days). The mechanical strength of the unmodified CS film was increased unequivocally with 2 wt% GNP loading with tensile strength of 23.56 Mpa. Furthermore, the current–voltage (I–V) characteristic curves for CS/GNP (2%) and CS/GNP (3%) showed similar current conduction and ohmic behavior in flat, bending, and flat‐after‐bending modes. The dielectric measurements revealed that the CS/GNP composite with 2 wt% filler exhibited optimal performance having permittivity (έ) of 32.71 (at 102 Hz) with low dielectric loss of 0.04 (at 106 Hz). These results suggest that the dielectric films offer strong prospects as an eco‐friendly alternative for various applications. Highlights: Biodegradable chitosan‐based flexible dielectric films were prepared.Films were made using a simple solvent casting method with 1–3 wt% GNP filler.Optimum physicochemical and electrical properties were seen at 2 wt% GNP.CS/GNP (2%) film exhibited ohmic behavior in both flat and bending modes.Excellent dielectric properties were achieved at 2 wt% GNP filler. [ABSTRACT FROM AUTHOR]

The emergence of Majorana fermion bound states has been studied in several environments. In this paper, we discuss the current-voltage characteristics of a Majorana fermion state as a function of the voltage, temperature, and magnetic field and compare the results to experiment. Based on the agreement and identified parameters, we calculate the noise as possible proof of the emergence of Majorana fermions. [ABSTRACT FROM AUTHOR]

In this work, we analyzed the temperature dependence of the current-voltage characteristics of the structure of glass/Mo/p-Sb2Se3/n-CdS/In. From an analysis of the temperature dependences of the direct branches of the I-V characteristic of the heterojunction, it was established that the dominant mechanism of current transfer at low biases (3kT/e0.8 V, the dominant current transfer mechanism is Newman tunneling. In the case of reverse bias (3kT/e

The results of studies of the current-voltage characteristics of a photodiode heterostructure are presented. Au-nCdS-nSi-pCdTe-Au, in forward and reverse directions. Photodiode heterostructures with an area of 29 mm² were created, which were obtained by vacuum evaporation in a quasi-closed volume by depositing layers of cadmium sulfide and cadmium telluride onto a single-crystalline silicon substrate with resistivity ρ = 607.47 Ohm⋅cm. A distinctive feature of the resulting photodiode Au-nCdS-nSi-pCdTe-Au structures is two-way sensitivity, where impurity complexes are formed. In the structures, the rate of recombination of nonequilibrium carriers at low excitation levels is determined by simple local centers in the boundary transition layers. The band diagram of a multilayer photodiode structure Au-nCdS-nSi-pCdTe-Au has been constructed. [ABSTRACT FROM AUTHOR]

The influence of the width of the quantum barrier (QB) in the form of a tunnel-thin carbon layer depleted of charge carriers in an enriched noncrystalline carbon matrix on the dissipative-free transport and field emission of electrons is studied. It is shown that the nonlinearities of transverse currents in heterostructures under static low-field electrical influences and the parameters of the current-voltage characteristics of the field emission of electrons in strong pulsed electric fields of a microsecond duration are determined by the parameters of the QB and the implementation of resonant tunneling conditions with the participation of various zero levels of size quantization energy. [ABSTRACT FROM AUTHOR]

A novel mathematical modeling approach for the Triple-Diode Model (TDM) and its parameter estimation is introduced in this paper. For the first time in the literature, this paper presents two analytical solutions for calculating the current in TDM solar cells using the Lambert W function. Additionally, a new metaheuristic algorithm, the Adaptive Evaporation Rate Water Cycle Algorithm (Adaptive ERWCA), is proposed for estimating TDM solar cell parameters. The proposed algorithm is tested using both the new analytical solutions and a well-known iterative approach for the current-voltage characteristics of the TDM solar cells model. Extensive testing is conducted on three well-known solar cells/modules and a panel under various weather conditions. The results demonstrate that the proposed analytical expressions for the current-voltage characteristics are accurate and highly effective for representing TDM solar cell current. The accuracy of the parameter estimates obtained with the application of the proposed algorithm, considering both analytical solutions and the iterative approach, is compared with existing literature results. It is shown that the proposed algorithm outperforms existing algorithms in solar cell parameter estimation across both the analytical and iterative approaches for current-voltage characteristics. Remarkably, for the RTC France solar cell, the SOLAREX MSX 60 solar module, and the PHOTOWATT-PWP 201 solar module, the obtained Root Mean Square Errors (RMSE) are 0.00075141, 0.01157153, and 0.0010578, respectively. These results are currently the best reported in the literature. [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.)

Photosensitive silicon/barium titanate/nickel structures with undoped barium titanate and doped europium were synthesized using the sol-gel method. The current-voltage characteristics were studied under illumination with a xenon lamp, highlighting a monochromatic line in the range of 400–800 nm and in dark mode. The synthesized structures showed the presence of a photocurrent on the reverse branch of the current-voltage characteristics over the entire studied range of illumination wavelengths. The maximum reverse branch current for a structure with undoped barium titanate was achieved when exposed to radiation with a wavelength of 470 nm and was about 0.6 μA for a bias voltage ranging from 2 to 10 V. Doping barium titanate with europium leads to an increase in the photocurrent by 17–26 %.

The influence of rapid heat treatment (450 °C, 7 s) on the electrical parameters of CMOS integrated circuits during the formation of ohmic contact between aluminum metallization and polysilicon is considered. The following volt-ampere characteristics of the dependence of drain current on voltage were chosen as the analyzed parameters of n- and p-channel transistors: at the gate when diode-connected; on the drain at different gate voltages; on the drain in the channel breakdown mode without applying potential to the gate. A comparison of these parameters was carried out with respect to microcircuits manufactured using standard technology (450 °C, 20 min) to form these contacts. Analysis of the results showed that the use of rapid heat treatment to form an ohmic aluminum-polysilicon contact can significantly improve the above characteristics of n-MOS and p-MOS transistors. From the current-voltage characteristics of n- and p-channel transistors it follows that in the region of gate voltages greater than 0.65 V, the drain current after long-term heat treatment is higher than after quick heat treatment. Analysis of the current-voltage characteristics of the drain current versus the drain voltage showed that the drain current when using long-term heat treatment is significantly higher than after rapid heat treatment. In this case, for long-term heat treatment, there is a decrease in the channel breakdown voltage only for n-channel transistors and an increase in the drain current in the region of more than 5 V for both n- and p-channel transistors. Such improvements occur by eliminating the formation of polysilicon conglomerates in the aluminum contact, significantly reducing the epitaxial recrystallization of silicon doped with aluminum on the silicon surface, as well as reducing the microrelief of the interface of this contact and reducing the growth in the size of contact windows due to the lateral interaction of aluminum with polysilicon.

Introduction. Quantum well infrared photodetectors (QWIP) are characterized by a wide application range. A large market demand for such photodetectors determines the importance of elucidating the principle of their operation.Aim. To carry out a research study into the influence of the AlGaAs potential barrier surrounding GaAs quantum wells on the QWIP operating bias voltage in the long-wavelength region of the spectrum (8…10 μm).Materials and methods. QWIP experimental samples were manufactured based on the GaAs/AlGaAs semiconductor material system using molecular beam epitaxy. The photosensitive (active) region of the structures contained 50 GaAs quantum wells with a thickness of 50 Å thick separated by AlGaAs barriers. Quantum wells were doped in situ with silicon as a donor impurity. The wavelength of the maximum spectral sensitivity of all samples ranged within 8…9 μm. The barrier width was the variable parameter. After passing the planar modification process route, the current–voltage characteristics were measured in all structures.Results. Reduction in the barrier thickness is capable of shifting the peak of photosensitivity towards the region of lower bias voltages with a slight increase in the dark current values.Conclusion. The study of the influence of the applied bias voltage presents both scientific and practical interest. On the one hand, the results improve the current understanding of the behavior of the dark current in QWIP. On the other, they provide the possibility of managing the maximum current sensitivity, shifting it towards the region of the required operating voltages of the multiplexers.

Historically, multi-junction solar cells have evolved to capture a broader spectrum of sunlight, significantly enhancing efficiency beyond conventional solar technologies. In this study, we utilized Silvaco TCAD tools to optimize a five-junction solar cell composed of AlInP, AlGaInP, AlGaInAs, GaInP, GaAs, InGaAs, and Ge, drawing on advancements documented in the literature. Our research focused on optimizing these cells through sophisticated statistical modeling and material innovation, particularly examining the relationship between layer thickness and electrical yield under one sun illumination. Employing III-V tandem solar cells, renowned for their superior efficiency in converting sunlight to electricity, we applied advanced statistical models to a reference solar cell configured with predefined layer thicknesses. Our analysis revealed significant positive correlations between layer thickness and electrical performance, with correlation coefficients (R2 values) impressively ranging from 0.86 to 0.96 across different regions. This detailed statistical insight led to an improvement in overall cell efficiency to 44.2. A key innovation in our approach was replacing the traditional germanium (Ge) substrate with Copper Indium Gallium Selenide (CIGS), known for its adjustable bandgap and superior absorption of long-wavelength photons. This strategic modification not only broadened the absorption spectrum but also elevated the overall cell efficiency to 47%. Additionally, the optimization process involved simulations using predictive profilers and Silvaco Atlas tools, which systematically assessed various configurations for their spectral absorption and current–voltage characteristics, further enhancing the cell's performance. These findings underscore the critical role of precise material engineering and sophisticated statistical analyses in advancing solar cell technology, setting new efficiency benchmarks, and driving further developments in the field. [ABSTRACT FROM AUTHOR]

Piezoelectricity is a well-known effect in a vast number of technologically important insulators and semiconductors and exists in 20 out of the 32 three-dimensional crystal classes. The piezoelectric effect is the driving mechanism behind several classical sensors and transmitters, and also most recently, in many nanodevices. Zhong Lin Wang coined the fields piezotronics and piezo-phototronics where the piezoelectric effect plays a dominant role. Piezoelectricity couples in a linear fashion mechanical strain to electrical fields and vice versa. In solids, there is another linear coupling between strain and the electric potential, known as the deformation potential effect. While linear in its coupling nature, this effect does not require the solid to be non-centrosymmetric in contrast to the piezoelectric effect. Moreover, the deformation potential effect is quantitatively huge and leads to changes in the conduction and valence band edges of III–V and II–VI materials of, typically, 50–100 meV in the presence of 1 % strain. Therefore, the deformation potential effect is essential to determine the electronic and photonic properties of bulk and nanostructure semiconductors in the presence of strain. In this work, we compute the relative importance of piezoelectricity and the deformation potential effect in the presence of lattice mismatch and external strain. We choose p − n junctions of ZnO/GaN structures but anticipate that the general conclusions can be carried over to other material structures. The main result of the present work is that both the inclusion of the deformation potential effect and piezoelectricity is crucial to correctly compute the effect of strain on p − n junction current–voltage curves and photonic properties. In our analysis of wurtzite heterostructures, the spontaneous polarization effect is also included but this effect appears to play a minor role for electronic and photonic properties. [ABSTRACT FROM AUTHOR]

In this work, we present an analytical DC model for the Gallium Nimtide High Electron Mobility Transistor by taking into account the finite width of the two-dimensional electron gas (2DEG) layer. The model predicts the vertical electric field in the device, especially at the interface of AlGaN and GaN layers, electrostatic potential, and energy band diagram are also obtained by the model. The general form of Gauss's law including piezoelectric and spontaneous polarization effect is employed to obtain this model in different regions from top to bottom of the GaN-HEMT. The model solves electrostatic equations in all regions of the device including two narrow regions around the AlGaN/GaN interface with thicknesses of about 3 nm. This model demonstrates how the triangular quantum well is formed around the AlGaN/GaN interface and varies as a function of gate voltages. Using the proposed electrostatic analysis and the treatment proposed by the EPFL HEMT model, the DC current-voltage characteristics are obtained by this model. The results predicted by the model are validated with TCAD simulations and in part with the EPFL HEMT model. The proposed model facilitates the following steps toward obtaining a complete model for small signal and large signal analysis of GaN HEMT. [ABSTRACT FROM AUTHOR]

To overcome the scaling limitations of large-scale charge-storage-based memories, the physical-based analytic model of a memristor with high-performance resistive random-access memory and low power based on Trilayer interlinked graphene oxide (TIGO) with significant charge transport as an active layer is proposed in this research. To this end, the electron transport of the proposed device is investigated with two electrode-limited conduction mechanisms based on Schottky emission (SE) and trap-assisted tunneling (TAT). In the proposed model, electrically driven reduction of oxygen groups makes the formation of sp2 islands across the TIGO layer. The TIGO-like islands operate as intermediate trap sites and help electrons to tunnel from the cathode toward the anode despite being isolated by the disordered sp3-bonded matrix. The existence of vertically aligned trap sites leads to the formation of percolation paths which allows a steady flow of electrons. The conductive path by the redox of TIGO atoms, because of the conversion of sp3 to sp2 oxygen functionalities, is produced, which can be modeled by degenerate region as ON state with the Low resistance switching (LRS). This path is also ruptured by declining the voltage into the reset voltage, which is modeled by the nondegenerate region as OFF state with High resistance switching (HRS). In fact, the resistance state of the proposed memristor can be reversibly switched by modulating the concentration of sp2 islands. To investigate the performance of the device, the density of states, carrier concentration, electrical conductance in the degenerate and nondegenerate regions, current density and current-voltage characteristics are obtained regarding the energy band structure. In order to verify the accuracy of the research, the models of SE and TAT for two bipolar and unipolar switching modes are compared together and a rational agreement is reported in terms of trend and value. Moreover, the effects of equivalent thermal resistance, interlayer distance, temperature and conductive filament evolution on current-voltage characteristic of the device are investigated. In order to determine the accuracy of the proposed analytical method in this study, the proposed SE and TAT models are compared with each other, and an acceptable agreement is observed. Moreover, the physical-based analytic model of the proposed device in comparison with the experimental data of monolayer graphene nanoribbon and trilayer-structured graphene counterparts is investigated for analogous ambient conditions and rational results are observed. The obtained results of the proposed analytical models and figures of merit for the proposed device showed a promising performance of Trilayer graphene nanoribbon (TGN) for high-performance memristor applications. [ABSTRACT FROM AUTHOR]

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]

In this study, a two-dimensional electron gas (2DEG), which is a conductive layer formed at the interface of Al2O3 and TiO2, was used as an electrode for resistive random access memory (RRAM) and implemented in a cell size down to 30 nm. For an RRAM device comprising W/2DEG/TiO2/W, we confirmed that the dominant switching mechanism changed from interfacial to filamentary as the cell size decreased from 500 nm to 30 nm. Through analyses of changes in forming characteristics and conduction mechanisms in the low resistive state depending on the cell size, it was identified that the 2DEG acted as an oxygen-scavenging layer of TiO2 during the resistive switching process. By comparing the switching characteristics of RRAM devices with and without 2DEG for a 30 nm cell size, we confirmed that a high-performance 2DEG RRAM was realized, with highly uniform current–voltage characteristics, a low operating voltage (∼1 V), and a high on/off ratio (>102). Finally, the applicability of the proposed device to a crossbar array was validated by evaluating 1S1R operation with an NbO2-based selector. Considering the improved switching uniformity, the 2DEG RRAM shows promise for high-density memory applications. [ABSTRACT FROM AUTHOR]

Evaluating the output of emitters and calibrating detectors using absolute power sensors is critical for public use. In free-space thermal power sensors, the measurement accuracy and sensitivity depend on the absorption characteristics of the absorber, and the response time relates to its intrinsic thermal time constant. A response time of a few seconds is useful in practical scenarios where factors such as power variations caused by changes in the current–voltage characteristics of the emitter are monitored. At the minimum, an intrinsic thermal time constant of a few tens of second is required to achieve a few-second measurement time because the actual time can be enhanced by the control method of the sensors. However, in the sub-terahertz region, conventional broadband absorbers must be adequately thick for high absorption, increasing thermal capacity. Thus, achieving high absorption and a good thermal response remains challenging. In this study, an absorber featuring a resin-hollow pyramidal structure covered with a metal film thinner than the skin depth was devised. To realize the proposed absorber, we used resin 3D printing and Ni–P electroless plating. A comparison with conventional absorbers demonstrated that the thermal time constant was comparable to that of a planar absorber, known for its suitable response but low absorption below 1 THz, while maintaining over 98.6% absorptance in the 0.1- to 0.3-THz range. These results can aid in the construction of a sub-terahertz power sensor with high accuracy, high sensitivity, and a few-second response time. [ABSTRACT FROM AUTHOR]

The effects of surface recombination on the steady-state carrier profiles and photocurrent in perovskite solar cells are investigated in this paper. The continuity equations for both holes and electrons are solved considering carrier drift and diffusion under the exponential carrier generation profile in the perovskite layer and considering both bulk and interface carrier recombination. An analytical expression for the solar-induced photocurrent is derived. The rate of carrier recombination at the interfaces has a very significant effect on the carrier profile, photocurrent, and, hence, on the charge collection efficiency. The external current density is calculated considering the dark current and nominal solar spectrum-induced photocurrent. The proposed model is fitted and verified with published experimental results from various publications. The fittings of the model with experimental results provide information about the interface and bulk charge carrier transport parameters. [ABSTRACT FROM AUTHOR]

This study explores the potential of β-SnSe monolayers as a promising material for ozone (O3) sensing using density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) method. The adsorption characteristics of O3 molecules on the β-SnSe monolayer surface were thoroughly investigated, including adsorption energy, band structure, density of states (DOSs), differential charge density, and Bader charge analysis. Post-adsorption, hybridization energy levels were introduced into the system, leading to a reduced band gap and increased electrical conductivity. A robust charge exchange between O3 and the β-SnSe monolayer was observed, indicative of chemisorption. Recovery time calculations also revealed that the β-SnSe monolayer could be reused after O3 adsorption. The sensitivity of the β-SnSe monolayer to O3 was quantitatively evaluated through current-voltage characteristic simulations, revealing an extraordinary sensitivity of 1817.57% at a bias voltage of 1.2 V. This sensitivity surpasses that of other two-dimensional materials such as graphene oxide. This comprehensive investigation demonstrates the exceptional potential of β-SnSe monolayers as a highly sensitive, recoverable, and environmentally friendly O3 sensing material. [ABSTRACT FROM AUTHOR]

Recent advancements in the efficiency of lead-based halide perovskite solar cells (PSCs), exceeding 25%, have raised concerns about their toxicity and suitability for mass commercialization. As a result, tin-based PSCs have emerged as attractive alternatives. Among diverse types of tin-based PSCs, organic–inorganic metal halide materials, particularly FASnI3 stands out for high efficiency, remarkable stability, low-cost, and straightforward solution-based fabrication process. In this work, we modelled the performance of FASnI3 PSCs with four different hole transporting materials (Spiro-OMeTAD, Cu2O, CuI, and CuSCN) using SCAPS-1D program. Compared to the initial structure of Ag/Spiro-OMeTAD/FASnI3/TiO2/FTO, analysis on current–voltage and quantum efficiency characteristics identified Cu2O as an ideal hole transport material. Optimizing device output involved exploring the thickness of the FASnI3 layer, defect density states, light reflection/transmission at the back and front metal contacts, effects of metal work function, and operational temperature. Maximum performance and high stability have been achieved, where an open-circuit voltage of 1.16 V, and a high short-circuit current density of 31.70 mA/cm2 were obtained. Further study on charge carriers capture cross-section demonstrated a PCE of 32.47% and FF of 88.53% at a selected capture cross-section of electrons and holes of 1022 cm2. This work aims to guide researchers for building and manufacturing perovskite solar cells that are more stable with moderate thickness, more effective, and economically feasible. [ABSTRACT FROM AUTHOR]

The unique properties of solid acid electrolytes, in particular CsH2PO4, are in many ways ideal for fuel cell operation. However, the technology is constrained by high cathode overpotentials. Here a simplified cathode geometry is employed to obtain the fundamental electrochemical parameters (exchange current density and charge transfer coefficient) describing the oxygen reduction reaction (ORR) at the CsH2PO4‐Pt‐gas interface. The parameters are incorporated into a 1D model of the voltage–current characteristics of realistic SAFC cathodes, which reproduced the measured polarization behavior of such cathodes without recourse to fitting adjustable parameters. Following this validation, the model is utilized to evaluate the impact of changes to cathode properties, microstructure, and operating conditions. Of these, the charge transfer coefficient, measured to have a value of ≈0.6 for ORR on Pt in the SAFC cathode environment, is found to have the greatest impact on power output. Nevertheless, even without material modifications, a combination of microstructural and operational modifications are identified with projected performance metrics meeting Department of Energy targets (0.8 V at 300 mA cm−2, and peak power density of 1 W cm−2), albeit at high Pt loadings. However, the analysis indicates that truly meaningful advances will likely necessitate the discovery of alternative ORR catalysts. [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]

This study assesses promising field electron sources based on silicon carbide monolithic field emission array (FEA). FEA is fabricated on single-crystal wafers of silicon carbide (0001C) 6H-SiC of n-type conductivity using the technology of two-stage reactive ion etching in SF6/O2/Ar atmosphere. To implement conditions close to breakdown, an experimental setup based on high-voltage narrow pulses generating device GKVI-300 was used. A series of nanosecond voltage pulses with amplitudes from 120 to 250 kV was generated. To study the characteristics of the FEA in the pre-breakdown state, the beam of field emitted electrons was separated from the ion torch or cathode plasma, formed in the following breakdown phases, by placing a 50-μm-thick titanium foil under zero potential into the interelectrode gap. Current-voltage characteristics of peak-currents vs. peak-voltages passing through the foil are close to rectilinear in the Fowler–Nordheim coordinates. The current-voltage characteristics plotted for each of the pulses along increasing and decreasing branches show a discrepancy (hysteresis). After the experiments, the silicon carbide cathode FEA was studied in a scanning electron microscope. [ABSTRACT FROM AUTHOR]

The paper shows that upon ignition of the combined gas discharge in the resonator chamber, there appears a double layer with diode properties that consists of layers of positive and negative charges surrounding the workpiece. An increase in the level of microwave power supplied to the chamber leads to a decrease in the equivalent diode resistance in open and closed modes and an increase in the current flowing through the unit. The ions of the process gas (nitrogen or argon) ionized by the microwave field fall on the product surface and diffuse into it as a result of the thermal diffusion process, which hardens the surface layer. The product is heated when a positive bias potential is applied to it by a stream of high-energy electrons arriving at the surface and accelerated to energies of tens and hundreds eV in the discharge acceleration zone. Ion-plasma implantation leads to a significant increase in the strength, wear resistance and corrosion resistance of the surface of the processed product. [ABSTRACT FROM AUTHOR]

The change in the characteristics of a solar battery as a result of a random abrupt change in the properties of individual solar cells, which occurred as a result of a single or systematic impact of adverse factors in near-Earth outer space, is considered. The choice of the calculation scheme for constructing a model of a single solar cell is substantiated. For this situation, analytical mathematical models of typical connections of solar cells have been developed. Using the developed models, the current-voltage and volt-watt characteristics of the solar battery are analyzed in the case of an abrupt decrease in the photocurrent of solar cells with different probabilities. A statistical analysis of the characteristics of damaged solar cells was carried out using simplified logical-analytical models with the introduced circuit loss coefficient. Estimates of the values of the coefficient of circuit losses for typical schemes for connecting solar cells are given. [ABSTRACT FROM AUTHOR]

The grazing X-ray diffraction study of phase-II NbS3 whiskers with charge density waves has shown that they exhibit pairs of broadened reflections from two close phases with the monoclinic angles β1 and β2 instead of single peaks. The phase with the smaller monoclinic angle β1 = 95.9°–97.2° is close in lattice parameters to phase I without charge density waves. Phase II with β2 = 99.9°–100.0° has a reduced b lattice parameter along the strongest bond, which implies an increased concentration of sulfur vacancies in this phase compared to phase I. It has been concluded that the studied whiskers have underwent a spinodal decomposition with the redistribution of sulfur vacancies resulting in the alternation of phases in the (001) direction perpendicular to the layers. A satellite structure indicating the formation of a superlattice with a period of 35.2 nm in this direction is observed in the most structurally perfect whisker of phase II. The spinodal decomposition is combined with high internal stresses present in whiskers with a monoclinic lattice. The partial spinodal decomposition is also observed in some phase-I whiskers without charge density waves with the appearance of thin layers of phase IV and phase II with the monoclinic angle β = 104°. The existence of thin layers of phase II in the bulk of phase I in such samples exposed to a high-frequency voltage has been confirmed by the presence of Shapiro steps on current–voltage characteristics. Spinodal decomposition should be taken into account to describe the properties of NbS3 whiskers nominally belonging to a certain polytype. [ABSTRACT FROM AUTHOR]

Samples of the CuCr1-xAlxO2 system with x = 0, 0.25, 0.5, 0.75, 1 were synthesized using conventional ceramic technology. X-ray diffraction phase analysis data indicate the formation of an unlimited solid solution in the system with the delafossite crystal structure (a = 2.97–2.95 Å, c = 17.1–16.9 Å, sp. gr. R-3 m). Scanning electron microscopy data show that in samples with x = 0.25, 0.5, 0.75, particles of large and small sizes are embedded into each other. The calculated average grain sizes of the samples vary from 1.2 to 7.5 µm. The temperature dependencies of the electrical resistance of the samples under direct current were studied in the temperature range from 77 to 300 K with electric field strengths of 0.001, 0.94, 1.27, and 1.5 kV/cm. The current–voltage characteristics of the samples were studied in the range of electric field strengths up to 4.5 kV/cm at temperatures of 120, 175, and 220 K. It was established that the application of a constant electric field of 0.94, 1.27, and 1.5 kV/cm leads to switching from a high resistance state to a low resistance state. This switching is manifested in the form of giant resistance jumps (up to six orders of magnitude) in the temperature range of 90–200 K, as well as in the form of S-shaped volt-ampere characteristics containing a region of negative differential resistance. An interpretation of the observed switching effect is provided based on the polaron mechanism of conductivity. [ABSTRACT FROM AUTHOR]

Cu3N films are investigated utilizing direct current magnetron sputtering from the Cu target in an Ar/N2 mixed sputtering gas. X-ray diffractive analysis, Ultra-violet absorption spectroscopy, X-ray dispersive spectroscopy, atomic force microscopy, field-emission scanning electron microscopy, Hall measurements, and I–V characteristic measurements are used to investigate the properties of the films. The study findings initially obtained films with a Cu3N composition at the appropriate substrate temperature of 80 °C. When the N2:(Ar + N2) gas ratio is more than 50%, the electrical property of films switches from n-type to p-type. The film obtains the greatest crystal quality and the best p-type electric property at the N2:(Ar + N2) gas ratio of 70%, with resistivity, hole concentration, and hole mobility of 1.18 × 10–2 Ωcm, 9.8 × 1019 cm−3, and 5.4 cm2V−1 s−1, respectively. A p–n Cu3N homojunction cell has an efficiency of 0.21%. [ABSTRACT FROM AUTHOR]

The demand for renewable energy has led to dramatic growth in the solar cell industry, where silicon-based devices dominate the market. However, recent developments in low-cost, high-efficiency, tuneable perovskite solar cells (PSCs) have made them very attractive over silicon solar cells. The highest efficiency is achieved in toxic Pb-based PSCs, but they have poor stability in air. Therefore, finding stable Pb-free perovskites with improved power conversion efficiency (PCE) is crucial. Here, CsSnI3 and CsSn0.5Ge0.5I3 perovskites are proposed for developing PSCs by simulating their efficiency with SnO2 as an electron transport layer and copper(I) thiocyanate as a hole transport layer (HTL). The optimal thickness and defect density of CsSn0.5Ge0.5I3 are extracted by analysing current–voltage characteristics and related PCE calculations, and the results demonstrate its superiority over CsSnI3. Optimized open-circuit voltage of 1.27 V, short-circuit current density of 28.35 mA/cm2, PCE of 32.73%, and fill factor of 90.28% are estimated at 280 K for CsSn0.5Ge0.5I3 with a CuSCN HTL. The PCE is further examined with different hole transport materials, and a maximum of 34.56% for a single junction is achieved for Cu2O. The present results clearly demonstrate the excellent potential of CsSn0.5Ge0.5I3 for developing the most efficient single-junction PSCs. [ABSTRACT FROM AUTHOR]

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Background. The object of study is an automated measuring system designed to measure the electrical parameters of semiconductor structures and devices. The subject of the study is the current-voltage characteristics of semiconductor structures and devices. The purpose of the work is to study the current-voltage characteristics of semiconductors using the example of a KT306A silicon transistor using an automated measuring system. Materials and methods. The structure of an automated measuring system for studying the current-voltage characteristics of semiconductor structures and devices is considered. The operating principles of the following methods for measuring semiconductor characteristics have been tested: voltmeter-ammeter, capacitive divider, bridge and resonant. Results. The volt-ampere characteristic of the KT306A silicon transistor was studied using an automated measuring system. The possibility of using the proposed measuring instrument to study the volt–ampere characteristics of TIR structures (metal-dielectric-semiconductor) when using a layer of tin dioxide doped with antimony as a transparent conductive oxide is shown. Conclusions. The structure of an automated measuring system for studying the volt-ampere characteristics of semiconductors is considered. The results of the approbation of this system are presented when measuring the electrophysical parameters of the KT306A semiconductor transistor, as well as the new metal-dielectric-semiconductor structure obtained by the authors based on antimony- doped tin dioxide synthesized by spray pyrolysis.

Background. Structures based on semiconductor materials are widely used in nano- and microelectronics devices. One of the promising directions is related to the production and research of transparent conductive films and structures based on them. The purpose of this study is to develop an automated information and measurement system for measuring the volt–ampere characteristics of semiconductor structures. Materials and methods. The information and measurement system is designed to study the volt-ampere characteristics of various semiconductor structures, including transparent conductive coatings obtained by spray pyrolysis on glass substrates. Results. The structure of the measuring unit of an automated information and measurement system is presented, which includes voltage and current measurement channels on the structure under study, as well as a thermal chamber, which allows us to study the temperature dependences of the electrical parameters of semiconductor components. Conclusions. A methodology for measuring the volt-ampere characteristics of semiconductor structures is described, which has been tested in the study of transparent conductive coatings synthesized on the basis of spray pyrolysis. Automation of measurement procedures has made it possible to reduce the time spent on the measuring process and eliminate the subjective components of measurement errors.