Electrophysical Parameters Research Articles

ELECTROPHYSICAL PARAMETERS INTERRELATION MODEL FOR CAD SYSTEMS

A model is presented and regularities are established for the relationship between the electrophysical parameters
 of a transistor structure and a two-dimensional channel, based on the self-consistency of the electrochemical
 potential and the concentration of charge carriers of a two-dimensional channel in a field-effect transistor
 structure. Such self-consistency is ensured by combining the Fermi – Dirac statistics with the condition of electrical
 neutrality of the transistor structure. The effect on the electrophysical parameters of a transistor structure
 with a two-dimensional semiconductor channel is considered for the band gap of the channel material, the capacitance
 of the gate dielectric, and the capacitance of interface states. The developed model of the relationship between
 the electrophysical parameters of a transistor structure with a two-dimensional channel can be used in computeraided
 design systems for the element base of micro- and nanoelectronics.

Investigation of the Effect of Combined Photo- and Thermal Annealing on the Structure and Properties of Zinc Oxide Films for Flexible Electronics

In this work, the evolution of the structural electrophysical parameters of nanostructured zinc oxide films, the preparation of a sol-gel by thermal treatment and combined treatment, including thermal exposure and UV exposure, were studied. It has been established that the use of thermal treatment of films leads to the formation of large aggregates (20—30 µm), density to enlargement with the duration of processing, while the structure of the material at a low level of the hierarchy, determined by the sensitivity of the sensitivity to analysis, as well as the optical band gap is practically independent from processing time. This is probably due to the formation of nanoparticles of the material responsible for the properties associated with the accumulation of the sol prior to its formation on the substrates. The introduction of additional UV irradiation into the system leads to the destruction of aggregates formed during heart failure and the formation of X-ray amorphous ZnO particles during treatment for 90 minutes. Increasing the processing time of the issuance to "crosslinking" the selection, the number of sizes of single crystals and the simultaneous increase in the concentration of point defects, leading to a decrease in the optical revealed band gap. Thus, the combined UV and heat treatment of the film makes it possible, on the one hand, to form a material with a nanocrystalline structure, and, on the other hand, to control its defectiveness. These results are promising for application in the manufacture of thermoelectric batteries, gas, catalysts and photocatalysts.

ELECTRICAL PROPERTIES INVESTIGATION OF Ag8GeS6 SINGLE CRYSTAL

The compounds of the argyrodite structure have high conductivity values in the solid state due to the simultaneous coexistence of a "rigid" anionic framework and disordered cationic sublattice. In this regard, argyrodites are considered to be promising superionic materials for use as a working element of solid-state batteries. This work presents the results of the study of the electrophysical parameters of Ag8GeS6 single crystal grown by directional crystallization from the melt technique. It was found by the XRD method that the grown Ag8GeS6 single crystal crystallizes in a low-temperature orthorhombic modification with unit cell parameters: a = 15.147 Å, b = 7.469 Å, c = 10.584 Å. The frequency (10 Hz - 0.3 MHz) and temperature (20 - 110°C) dependence of the electrical conductivity was studied on a single crystal plate of Ag8GeS6 oriented in the (011) plane by impedance spectroscopy. The frequency dependence of the total electrical conductivity of Ag8GeS6 shows an increase in the total electrical conductivity with increasing frequency, which is typical for mixed ionic-electronic conductors. It was determined that the total conductivity of the Ag8GeS6 single crystal is 3.82 × 10-5 S/cm, and the activation energy is 0.728 eV.
 Keywords: argyrodites; single crystals; electrical conductivity; phase analysis.

Automated system for measuring electrophysical parameters of semiconductor structures

Automated system for measuring electrophysical parameters of semiconductor structures

Electrophysical Parameters and Emission Spectra of the Glow Discharge of Difluorodichloromethane

The effect of the external discharge parameters on the electrophysical parameters and emission spectra of difluorodichloromethane plasma is analyzed. Data on the reduced electric field strength and gas temperature are obtained. It is established that the reduced electric field strength in difluorodichloromethane plasma decreases markedly with increasing gas pressure (at a constant discharge current). It is shown that a linear increase in the gas temperature with increasing pressure is due to the increase in the specific power deposited in the discharge. Atomic and molecular components are found in the emission spectra of the glow discharge of difluorodichloromethane. It is established that, with increasing current, a linear increase in the radiation intensity occurs, which corresponds to the mechanism of the direct excitation of the radiating states upon electron impact and indicates the absence of secondary processes.

Automated system for measuring electrophysical parameters of semiconductor structures

сThe article is devoted to the development of an automated information and measurement system for measuring the voltfarad characteristics of semiconductor structures, including structures based on transparent conductive coatings. The structure of the information-measuring system is proposed, the results of functional and metrological analysis of the measurement channel of complex conductivity are presented. In particular, as a result of functional analysis, the functions of converting complex conductivity into a digital code proportional to the capacitive component and the active component of conductivity are obtained. In the process of metrological analysis, a metrological structural model of the complex conductivity measurement channel has been compiled, which, unlike the functional model, takes into account additive, multiplicative errors of the links, as well as the quantization error of the analog-to-digital converter. Expressions are obtained for the real functions of converting complex conductivity into a digital code proportional to the capacitive and active component of conductivity, taking into account the instrumental errors of the links that make up the measuring channel. Metrological analysis makes it possible to solve both the direct problem of calculating the instrumental error of the measuring channel according to the known nominal parameters and errors of its constituent links, and the inverse problem, which consists in assigning requirements to the metrological characteristics of the links in the measuring channels to ensure the required value of the maximum measurement error. In particular, based on the metrological analysis performed, it was found that the limits of the permissible relative error of capacitance and conductivity measurements do not exceed ±3 %, which is confi rmed experimentally. The developed automated information and measurement system allows not only to measure the volt-farad characteristics of the studied semiconductor structures, but also to process measurements in order to determine the electrophysical parameters by an indirect method.

Исследование проницаемости и преломления плоскополяризованной ЭМВ при взаимодействии с диэлектрической киральной средой

Based on consideration of the well-known Maxwell and Maxwell–Garnett relations for dielectric substrates, presented in the form of a bulk dielectric (alloy) with chirally-coupled bulk structures distributed in it (for example, left-handed and right-handed spirals), two algorithms are proposed, determining the main connected with each other parameters of the chirality coefficient, concentration of chiral particles and permittivities. This part of the work is of a theoretical nature and is considered in relation to the microwave frequency range. In the second part of the work, a method is given for finding the refractive index of a plane-polarized EMW as it passes through a chiral medium. In this case, an original method is used, based on the relationship between the chirality coefficient and the angle of rotation of a wave that has passed through a given medium with given electrophysical parameters.

Preparation of wells using an electrohydraulic drill and modeling of heat transfer processes in heat transfer elements of a heat pump

The article discusses the use of innovative electrohydraulic technology in the preparation of vertical ground heat exchangers to create heat supply using heat pumps. The discharge energy in the operating range varied E=900÷2600 J. The most economical mode of operation of the electrohydraulic installation is carried out with the following parameters: discharge voltage 30÷51 kV, capacitor bank capacity 2 µF and interelectrode distance 8÷15 mm. It is determined that the optimal energy of destruction of natural materials depends on their thickness. Based on the research, the limits of the electrophysical parameters of the approach were established, at which the concentrated destruction of hard rocks – the main stones ‒ begins. The effective amount of energy for the destruction of stones with a thickness of 53 mm is 900 J. For stones with a thickness of 78 mm, there should be 2600 J. If to increase the energy of the discharges to 1837 J, the process of complete destruction of the stones is underway. Using an electro hydraulic drill, we have prepared vertical wells up to 25 m deep. In the future, we have installed special temperature sensors along the length of the pipes, inside the well. Using a software product (Temp Keeper), data from temperature sensors are received in real time. This program allows to visually monitor temperature changes occurring at a local point. Temperature and time dependences are also obtained at coolant velocities of 0.2÷0.4 m/s. A significant decrease in the temperature in the well and at the outlet was observed at a coolant velocity of 0.35 m/s for one hour. The study conducted on the basis of the data obtained enables to achieve higher optimal drilling performance compared to conventional installations

Changes over time in ferroelectricity of nanocomposites containing cellulose combined with [NH4][Zn(HCOO)3

ABSTRACT For the first time, a composite based on a ferroelectric metal-organic framework of [NH4][Zn(HCOO)3] combined with nanocellulose at different cellulose concentrations from 0 to 75 wt% was synthesised to investigate the changes over time in phase transition and ferroelectric switching. A comparative study for fresh samples and the samples after 288 h was conducted. Electrophysical parameters were measured in a temperature range of 140 to 245 K under a weak electric field with an amplitude of 2 V.cm−1 at a frequency of 1 kHz. The results indicated that the increase in cellulose content led to increasing the phase transition temperature from 190.1 to 238.5 K. Besides, the coercive field was also found to increase from 3.78 to 14.12 kV.cm−1 along with the reduction of dielectric permittivity and maximum polarisation. After 288 h, this phase transition decreased significantly over time even to 231.6 K in the case of highest cellulose content (75 wt%). Meanwhile, the coercive field was found to decrease from 14.12 to 10.57 kV.cm−1. Remarkable changes were detected for samples with cellulose content of higher 25 wt%. The weaker interaction between ferroelectric part and cellulose over time due to the softness of cellulose was responsible for the obtained phenomena.

Evolution of underwater shock wave in far-field regime of electrical wire explosion system over wide range of electric pulse energy

The parametric relationships between underwater shock waves (SWs) in far-field regime and electrically exploded wire under different charging voltages of a generator are investigated. Contributions of the vaporization and current restrike to the resulting SWs have been examined by means of electro-physical diagnostics, free-field pressure probe, and high-speed photography. In the experiment, a 6-μF pulse capacitor is adopted to provide a microsecond timescale pulsed current, exploding a 90/185-μm-diameter, 2-cm-long copper wire with the charging voltage ranging from 7.1 kV (stored energy ∼ 150 J) to 18.3 kV (∼1000 J). Experimental results indicate that as the increase of the charging voltage, the relationship between electro-physical and shock wave parameters shows a rather complex situation. When the charging voltage ranging from 7.1 kV (∼150 J) to 11.6 kV (∼400 J), the peak pressure of SWs (300 mm away from the explosion source) increases almost linearly from 1.16 ± 0.03 to 2.24 ± 0.05 MPa (90-μm wire), and 1.67 ± 0.17 to 2.87 ± 0.12 MPa (185-μm wire). Nevertheless, at a higher charging voltage between 11.6 kV (400 J) to 14.1 kV (600 J), the peak pressure stabilizes in a strange “plateau”. Until the residual energy after the explosion is sufficiently large (>600 J in this study) to induce a strong current restrike, the development of the plasma channel could further enhance the expansion of explosion products, as well as the intensity of measured SWs. In addition, high-speed photography has been applied for those explosions, providing the information of plasma channel expansion and initial SWs propagation.

Sintered powder high-entropy target cathodes for wear-resistant coatings

Modern machine-building production equipped with high-performance mechatronic systems and numerically-controlled and adaptive control machines for blade cutting of heat-resistant chromium-nickel and titanium alloys requires increasing the operating properties of cutting tools working at high temperature-force loads in the contact zone, respectively with a significant stress-strain state of the cutting wedge. It is possible to solve the problem of increasing wear resistance and serviceability by developing and introducing new tooling material, as well as by applying wear-resistant coatings. The paper presents the results on development of technology for obtaining high-entropy target cathodes by spark plasma sintering with subsequent application of wear-resistant coatings on metal-cutting tools by both magnetron and ion-plasma methods. Samples of sintered high-entropy target cathodes of different compositions (more than fourteen) and at different modes of their sintering (depending on temperature in five modes) with their subsequent optimization and two standard sizes (20 and 80 mm) were obtained for further application of wear-resistant coatings on the magnetron unit. The authors carried out structural and phase analysis and studied physicomechanical properties of the obtained high-entropy target cathodes: density, hardness, electrical conductivity, emissivity. The possibility of obtaining high-entropy target cathodes by spark plasma sintering was confirmed experimentally, and the effect of sintering temperature on structure and properties of the sintered samples of high-entropy target cathodes was established. Dependence of physicomechanical and electrophysical parameters of target cathodes on technological modes of spark plasma sintering is shown.

Reduction of the Electrical Resistance of Grounding Devices by the Use of a Soil Replacement Mixture Based on Graphite and Hydrogel to Stabilize the Electrophysical Parameters of the Soil

This article discusses the factors that affect the electrical resistance of the current spreading of the grounding device. The issue of the electrophysical parameters of the soil that affect its resistivity and the consideration of such parameters in the design of grounding devices is considered. It is shown that keeping moisture in the near-electrode space of the grounding electrode, as well as maintaining it at a certain level, facilitates improving the quality and reliability of the grounding. A relationship has been established between the ability to retain moisture and the magnitude of seasonal fluctuations in the electrical resistance of the soixl, and also the season factor, which takes into account changes under different climatic environmental conditions. The issues of application of various methods of reducing the resistivity of the soil during mounting of grounding devices are considered. One of the main ways to reduce ground resistance is the use of solutions of various mineral salts. This method is not optimal, as it accelerates the corrosion processes in the materials of the ground electrodes. Therefore, the paper also considers other ways to reduce the resistance of the ground loop; in particular, the authors propose a method for reducing the resistance of a grounding device based on the method of partial replacing the soil in the near-electrode region with a mixture with a lower resistivity capable of collecting moisture based on graphite and hydrogel. This type of mixture is environmentally friendly when used, as well as it is non-aggressive to the material of the ground loop. The principle of operation of this mixture is based on the fact that the hydrogel makes it possible to stabilize the moisture at the site of laying the circuit, while graphite increases the overall conductivity of the mixture. The paper presents the results of laboratory studies, which have been carried out in accordance with GOST 9.602–2016. For this purpose, control samples were placed in containers made of a non-conductive material (plexiglas) and dependence of resistivity on moisture, temperature, specific content of graphite and hydrogel was measured. The article presents graphs of the dependences of the mixture specific resistance on moisture, temperature, and the quantitative content of the hydrogel. From the results obtained, it can be concluded that the mixture in can be used in the energy sector to improve the reliability of electrical installations and ensure electrical safety.

Automated Study of Electrophysical Properties of Polymeric and Composite Materials

The use of secondary resources and composites in modern polymer materials would make it possible to reduce the cost and change the physical and mechanical properties of the packaging material. The use of composites to impart new properties to polymers complicates the implementation of technologies for the production of products from them, which prevents the improvement of product quality. This is due to the lack of an accumulated database and methods of predictive determination of the obtained properties of composite materials and polymers produced with the use of secondary raw materials. (Research purpose) The research purpose is testing the methodology of automated determination of electrophysical parameters of polymer and composite thermoplastic materials. (Materials and methods) A resonant method of monitoring the electrophysical parameters necessary for an energy-efficient method of high-frequency electrothermal heating of polymers has been substantiated. We selected and modified with the installation of an automated monitoring and data collection system cumeter with a working chamber from a standard cell, retrofitted with a heating system and thermal insulation. (Results and discussion) The results of the use of an automated process of control and determination of electrophysical parameters of polymer and composite materials based on polypropylene, polyethylene with a composite of titanium dioxide were presented. The method of establishing analytical dependencies for calculating the correction coefficient when calculating the effect of thermal insulation material (dielectric cardboard) and air gap in the working capacitor on the even electrophysical parameters of the polymer and composite under study was shown. (Conclusions) The possibility of conducting automated studies to determine the dielectric properties of polymer and composite materials using the developed automated control system for the process of control, transmission, processing, visualization and storage of information about the dielectric properties of ε, ε», tgδ polymer and composite materials was substantiated. The heating temperature ranges of polymer and composite materials PP H030 GP/3 TS and 1060PE were identified in automatic mode in order to organize the most energy-efficient operating modes of high-frequency electrical equipment.

Radiofrequency Sensing Method and Algorithm of Inhomogeneous Conductive Structures

The paper proposes a method and algorithm for frequency probing of the internal inhomogeneous structure of electrically conductive objects based on the skin effect for diagnostics and control. The essence of the method consists in frequency control of electromagnetic field penetration depth into an electrically conductive object, and according to the measured frequency characteristic of the surface impedance, the profiles of electrophysical parameters characterizing the structural properties of the medium under study. An electrical model of an inhomogeneous medium with distributed RL parameters has been developed on the basis of electrodynamic presentations. The relationship of resistance and inductance linear parameters of the electrical model with the local parameters of the conductive medium results from their relationship with the electrical resistivity and magnetic permeability of the medium. The mathematical model of an inhomogeneous conducting medium is based on the Riccati equation with respect to the impedance characteristics of the medium. The mathematical statement of the probing problem is formulated as an inverse operator problem solution of mathematical physics. A numerical iterative algorithm for inhomogeneous medium frequency sensing based on Tikhonov regularized solution of the inverse problem is proposed. The proposed algorithm can also be extended to probe the internal structure of semiconductor and low-conducting objects containing a capacitive component in the impedance. The results of numerical simulation of the proposed algorithm for various distributions of inhomogeneity in the frequency characteristics of the impedance, measured with a known error, are presented. Solutions to various control and measurement problems in thermophysical applications based on the proposed method are given in the patents of the authors.

Evolution of the macroresponses during the transition from two-to six-component systems of the solid solutions with fundamentally different properties

The solid solutions (SS) of the n-component (n = 2 … 6) systems with the participation of two fundamentally different bases – (Na, K)NbO3 (NKN) and Pb(Ti, Zr)O3 (PZT) have been prepared by the two-stage solid-phase synthesis followed by the conventional sintering ceramic technology. Evolution trends of the structural and electrophysical parameters at such a complication of the compositions have been established. It is shown that with an increase in the number of the components in the systems, the spontaneous deformation, characterized by a uniform deformation parameter, δ, decreases, which, due to the existing correlations, leads to a decrease in the Curie temperature and an increase in the relative permittivity. The extreme “behavior” of the piezoelectric characteristics is associated with the competing influence of the permittivity and remanent polarization on them. A conclusion is made about the expediency of using the obtained results in the creation of similar materials and devices based on them.

Concentration of Fluorine Atoms and Kinetics of Reactive-Ion Etching of Silicon in CF4 + O2, CHF3 + O2, and C4F8 + O2 Mixtures

A comparative study of the electrophysical parameters of the plasma, the fluorine atom concentra-tions, and the kinetics of reactive-ion etching of silicon in CF4 + O2, CHF3 + O2, and C4F8 + O2 mixtures of a variable (0–75% O2) initial composition is carried out. It is shown that the dominant etching mecha-nism is always the ion-stimulated chemical reaction Si + xF → SiFx, whose rate has a maximum in the region of 20–50% O2. Based on the results of plasma diagnostics, it is found that the similar behavior of the concen-tration of fluorine atoms is typical only for mixtures of CF4 + O2 and CHF3 + O2, while in the C4F8 + O2 mix-ture, there is a nonmonotonic change in the probability of the interaction. It is assumed that the latter effect is caused by the competition between the processes of reducing the thickness of the fluorocarbon polymer film and the oxidation of the silicon surface by oxygen atoms.

Influence of Structural Defects on the Electrophysical Parameters of pin-Photodiodes

The results of studies of electrophysical parameters of pin-silicon-based photodiodes, depending on their operating modes (external bias and temperature), manufactured on single-crystal silicon wafers of p-type conduction orientation (100) with ρ = 1000 ohm cm, are presented. The p+-type region (isotype junction) is created by the implantation of boron ions; the n+-type region, by the diffusion of phosphorus from the gas phase. It is established that on the voltage-current characteristics under reverse bias, three regions of dark cur-rent variation depending on the applied voltage can be distinguished, sublinear, superlinear, and linear, caused by various mechanisms of the generation-recombination processes in the depletion region of the pn-junction. A noticeable dependence of the barrier capacitance value (at a frequency of 1 kHz) and the size of the depletion region on temperature is observed only when the applied reverse voltages do not exceed the contact potential difference (V ≤ 1 V).

Electric-field-controlled deformation and spheroidization of compound droplet in an extensional flow

A 3-dimensional numerical model is developed by employing the electric current model and the phase-field method to investigate the electric-field-mediated compound droplet deformation and spheroidization in an extensional flow field (EFF). Based on this model, the detailed deformation morphologies of the compound droplet under different electrophysical properties are presented and the underlying electrohydrodynamics are clarified. Furthermore, the regime diagrams for quantificationally identifying different droplet deformation characteristics are summarized. In particular, the quantitative electrohydrodynamic criterion is obtained for achieving the droplet spheroidization in an EFF via the active electric field (EF) regulation. It is found that by applying a proper EF, the hydrodynamic force imposed by the EFF on the compound droplet and the flow-field-induced morphology deformation can be completely counterweighted. The deformation types and degrees of the compound droplet are determined by the fluids’ electrophysical parameters (especially the conductivity ratio R01 and permittivity ratio S01), EFF strength, and EF strength. Within the current research scope, the compound droplet can be restored to a spherical shape only when R01S01>1. Specifically, under a proper R01S01 (7≤ R01S01≤10 in the current simulation), the changing rate of the deformation of the outer droplet and inner droplet can match exactly and the two droplets can reach a spherical shape (i.e., S-S shape) simultaneously. Furthermore, the critical electric capillary number (CaE) for the compound droplet spheroidization is almost linearly related to the capillary number (Ca), which can be expressed as CaE=kCa. The factor k decreases with an increasing R01S01, so a larger R01S01 helps the compound droplet maintain its spherical shape.

Thermotropic liquid crystal doped with silica, silica grafted with aniline (ANI@SiO2) and polyaniline (PANI@SiO2)

ABSTRACT Nanoparticles dispersed in liquid crystals exhibit novel and intriguing properties, which make them suitable materials for displays and photonic applications. This paper reports on the impact of non-modified silica (SiO2), silica grafted with aniline (ANI@SiO2) and silica grafted with polyaniline (PANI@SiO2) nanoparticles on the physical parameters of 7CB liquid crystal. A slight change in the nematic-isotropic phase transition temperature was observed. The results from dielectric experiments revealed an increase in free ion concentration in the doped samples. By fitting a suitable equivalent electric circuit model to the experimental data, we demonstrate changes in the electro-physical parameters of the liquid crystal in the bulk and at the liquid crystal-metal electrode interface. Therefore, we were able to calculate the ion mobility and the diffusion constant. It was also demonstrated that the doping of 7CB with the above-mentioned nanoparticles increases the response time, thresholds, and viscosity.

ON THE COMPARISON OF REACTIVE-ION ETCHING MECHANISMS FOR SiO2 AND Si3N4 IN HBr + Ar PLASMA

This work investigated the influence of component ratio in the HBr + Ar gas mixture on electro-physical plasma parameters, steady-state densities of active species and reactive-ion etching (RIE) kinetics for SiO2 and Si3N4 under conditions of inductive RF (13.56 MHz) discharge. The combination of plasma diagnostics by Langmuir probes and plasma modeling indicated that an increase in Ar content at constant gas pressure and input power a) caused an increase in electron temperature and densities of charged species; b) results in increasing ion bombardment intensity; and c) leads to the nearly proportional decrease in Br atoms density and flux. It was found that variations of SiO2 and Si3N4 etching rates vs. mixture composition are qualitatively similar while the maximum difference in corresponding absolute values takes place in pure HBr plasma. The analysis of RIE mechanisms was carried out using model-predicted data on fluxes of ions and bromine atoms. It was found that the dominant SiO2 etching mechanism is the ion-assisted chemical reaction which is characterized by the nearly-constant rate in the range of 0–80% Ar due to an increase in the effective reaction probability. That is why the noticeable intensification of physical sputtering with increasing Ar fraction in a feed gas causes the only weak growth of obtained SiO2 RIE rate. Oppositely, the Si3N4 etching process is mainly contributed by the physical sputtering while the efficiency of ion-stimulated chemical reaction is limited by the low reaction probability. This provides both slower etching process (especially in Ar-poor plasmas) and stronger sensitivity of etching rate to the change in mixture composition. For citation: Efremov A.M., Betelin V.B., Kwon K.-H. On the comparison of reactive-ion etching mechanisms for SiO2 and Si3N4 in HBr + Ar plasma. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 6. P. 37-45. DOI: 10.6060/ivkkt.20236606.6786.