The analysis of the mechanism underlying the formation of the current-voltage characteristic in light-emitting diode structures with multiple quantum wells, along with the solution of the thermodynamic potential equation of the crystalline lattice, has revealed the mechanism responsible for the formation and accumulation of nonequilibrium Frenkel-type point defects in the quantum well (QW) region. This mechanism operates alongside other potential mechanisms associated with diffusion-stimulated complex rearrangement, the influence of piezoelectric fields, and mechanical stresses. This study demonstrates that according to this mechanism point defects are generated as a result of interactions between hot charge carriers, injected into the QW region, and the atoms of the crystalline lattice. The heating of charge carriers in the QW region occurs due to the electric field created by the charges of excess carriers within the QWs. An equation is presented for calculating the concentration of point defects as a function of operating time and forward current density.

Due to the constant reduction in the size of interconnects (based on Al, Cu, etc.) in microelectronic structures, the associated thermal load is constantly increasing. Therefore, it is important to study the heating dynamics of interconnect in pulsed modes. In this work, the temperature modes of operation of an Al-Si binary structure were simulated using the finite element method. The results of numerical modeling of thermal behavior of Al-Si structures were compared with experimental data obtained at various pulse energies (Wτ = 0.5–5.5 J) and duration up to 500 µs. Comparison showed that discrepancy between experimental results and numerical modeling results exceeded 10

An analysis of the applicability of the ABC recombination model to describing the current dependence of the internal quantum efficiency (IQE) demonstrates its inadequacy. The main criticisms are as follows: – The use of a secondary parameter for quantum-well device structures, namely the excess carrier concentration, as the argument in the current dependence of IQE, especially under the assumption of equal electron and hole concentrations in the space-charge region; – Auger recombination and radiative recombination are partial components of a unified inter-band recombination process and therefore cannot be treated as independent processes; – The ABC model unjustifiably ignores the fundamental mechanism of tunneling current formation; – In the ABC model, the origin of the nonradiative current is attributed to the Shockley – Read – Hall recombination mechanism, whereas in the device structure it is governed by the Sah – Noyce – Shockley mechanism. Based on this critical analysis, it is concluded that an adequate model describing the IQE – current dependence should be developed on the basis of the physical mechanisms governing the fundamental currents in quantum-well device structures: – The recombination current via defect levels in quantum wells, Jt; – The inter-band recombination current, JB; – The tunnelling current, JT. Such a model should also account for the unified mechanism responsible for the formation of the radiative component of inter-band recombination, (1‑p)・JB, and the nonradiative component, p・Jb, where p is the partition coefficient dependent on JB. A general expression for the current dependence of IQE is proposed as follows: ηIQE=(1‑p)・ JB /(Jt+JB+JT).

This study analyzes the creep processes of a heterogeneous aluminum alloy containing ferromagnetic inclusions with an average size of 3–5 μm, and the influence of preliminary magnetic exposure (in a constant magnetic field (MF) with induction B < 0.75 T) on these processes. Experimental investigations were carried out to determine the characteristic times of the transient stages of short-term creep, which do not exceed approximately 25 ms. We analyzed the transient deformation behavior of the aluminum-based alloy and consequently determined the elastic moduli of the material, along with the influence of preliminary magnetic exposure on them. It was established that the MF has the most pronounced effect on the “long-term” elastic modulus H (defined as the ratio of stress to the relative strain of the material after sustained application of a constant load). We propose that the observed linear decrease in H with increasing B is associated with the magnetostriction of the inclusions during preliminary magnetic exposure. An increase in magnetic induction enhances local stresses at the matrix–inclusion interfaces, which in turn leads to a rise in dislocation density. These microstructural changes influence the subsequent deformation behavior, including both transient responses under loading and stress relaxation during unloading. We conclude that the elastic modulus H is the most sensitive parameter to the influence of magnetic fields, indicating a significant impact of external MF on the creep dynamics of the structurally heterogeneous aluminum alloy under investigation.

The behavior of current-voltage characteristics (CVC) within the classical Shockley and Shockley-Noyce-Sah models depending on the nature of the distribution of recombination centers in the space charge region of the p-n junction was analyzed. Notably, the non-ideality factor determined from experimental CVC cannot be introduced into the exponent of the mathematical model of the CVC because it is unrelated to the physical nature of the exponentials of classical models but indicates the voltage dependence of the pre-exponential factor of the recombination component of the total current. The exponential factor of the model with a non-ideality factor describing the experimental CVC presents only a mathematical approximation of a small portion of it.

In this article, we investigate the development and use of thermal memory elements based on thin-film aluminum devices on silicon wafer. To stabilize their operation and reduce the number of errors during the read/write process of thermal information in such devices, we propose an algorithm (referred to as the floating zero algorithm) for adjusting the temperature conditions of thermal memory cells. This algorithm controls the thermal memory cells on silicon under varying ambient temperature conditions. We tested the algorithm performance using an experimental thermal memory sample at room temperature. Additionally, we conducted a study on the degradation process of the sample under high electrothermal loading conditions. The results showed that the degradation process in the sample starts when a single current pulse of duration τi ≥ 100 µs and amplitude density ji ≥ 8.5 × 1010 A/m2) flows through the device. We propose a criterion for determining the safe operation area γ of the device under investigation and experimentally determine its value γ = 6.0(VA√s).

The paper presents the results of gas dynamic calculation and strength analysis required to optimize the mathematical model of the body of the catalytic collector of a passenger car. Based on the obtained results of numerical modeling, the optimization of the case was performed. As a result of the gas-dynamic calculation, the optimal variant of the catalytic collector housing with the required uniformity of the exhaust gas flow in the input section of the catalyst (coefficient of unevenness (UI > 0.8)) was selected. According to the results of the strength analysis, stainless steel was selected to withstand emerging mechanical stresses at maximum temperatures up to 600 °C.

Based on long-term experimental studies and analysis of the specific features of the current-voltage characteristics of quantum well light emitting diodes (LEDs), based on wide-bandgap semiconductors, it has been found that modern quantum well LEDs have an inherent limitation on their operating current density, determined by existing design and technological parameters. This limitation is associated with the formation of a built-in electric field within the quantum well region, caused by the injection of excess charge from the incoming charge carriers. When such a built-in electric field forms in the quantum well region the efficiency decreases inversely with the potential difference between the outermost quantum wells, that is, inversely with the increasing current density. Thus, a multiple quantum well structure can be modelled as a multi-plate parallel-plate capacitor, where the stored charge is proportional to the charge of the injected excess carriers or depends exponentially on the voltage that lowers the potential barrier of the space charge region. As a result, once a certain current density threshold is exceeded, the external voltage across the LED structure increases sharply. The current density, at which the excess voltage U-i appears, is approximately the same for all quantum well LEDs with existing design and fabrication parameters. This threshold can be described by the expression J(& Kcy;& Rcy;)=(2kT epsilon epsilon(o))/(q(2)tau L), where tau L is the product of the carrier lifetime in the quantum wells and the distance between the outermost wells. This value typically falls within the range of (1-10) A/cm(2).

The article proposes a physical and mathematical model of the current–voltage characteristic (CVC) of light-emitting diode structures with quantum wells based on high band gap semiconductors using the Sah–Noyce–Shockley recombination mechanism. The article also describes the mechanism of the current–voltage characteristic generation at high forward current densities. It is demonstrated that the deviation of the current–voltage characteristic from the exponential dependence at high current densities is associated with the formation of a built-in electric field between the quantum wells inside the space charge region and, as a consequence, with an additional voltage drop. The distinctive feature of the model is that recombination in quantum wells does not occur through local centers but between the semiconductor zones in quantum wells. The developed model can be used to provide sound explanations for a set of experimental facts.

The principle of operation and block diagram of a device for determining the temperature of the spatial charge region of LEDs based on recording the dynamics of changes in direct voltage during pulsed direct current heating and subsequent cooling of LEDs are described. The results of experimental studies of low-power GNL-3014PGC LEDs are presented.

The work carried out an experimental study of the features of thermal destruction of Al-Ti-Si, Al-SiO2-Si and Al-Si systems under pulsed current exposure. The dynamics of heating systems at current densities j>3•1010 A/m2 and durations up to 500 μs are presented. The initial stages of melting processes in thin-film systems and the mechanisms of destruction of structures during the passage of a single rectangular current pulse have been identified. Thus, the presence of a Ti sublayer increases the thermal stability of a multilayer system; the main mechanisms of destruction of structures are associated with the phenomenon of electrical transfer, as well as the migration of molten zones in the temperature gradient field after turning off the pulse near a local heat source. The presence of a dielectric sublayer of SiO2 leads to increased thermal loads on the metallization system (at j=3.1010 A/m2 and pulse duration up to 450 μs) compared to the Al-Si structure.

The influence of the degree of plastic deformation at room temperature, followed by aging, on the amplitude dependence of internal friction and microstructure of the pre-hardened alloy ZA27 was investigated. The main structural mechanism affecting the amplitude dependence of internal friction under these treatments was analyzed.

A measuring device designed to gauge the distribution of electrically charged impurities within strongly asymmetric p - n junctions, Schottky barriers, and metal - insulator - semiconductor structures, employs the capacitance - voltage method. This device is controlled by a personal computer through a microcontroller. The coordinates of the concentration profile points are determined through a simultaneous selection of signals proportional to the concentration and its spatial coordinate, achieved by the selective hardware separation of information frequencies from a polyharmonic voltage. This process occurs in a structure installed in the negative-feedback circuit of the operational amplifier. The entire profiling process takes 30 seconds. It boasts a depth resolution of 15 angstroms (equivalent to 3-4 atomic layers of the crystal lattice) at an impurity concentration of 5 x 1017 cm-3, with a maximum measured concentration of 5 x 1018 cm-3. The dimensions of the measuring device are 180 x 120 x 50 mm. The study presents examples of its practical applications.

The paper illustrates the effect of 0.2–0.7 T magnetic fields on aluminum alloy creep. The creep of the alloy, following its preliminary holding in a constant magnetic field, was found to augment, demonstrating its magnetic memory. The dependence of creep on the induction magnitude of a constant magnetic field B was revealed, where the alloy creep proliferates linearly with an increase in B. The alloy was established to comprise Fe-Al (Fe4Al13) type microinclusions identified by electron microscopy, magnetometry, and diffractometry. Plausible mechanisms for modifying the states of ferromagnetic microinclusions and the aluminum matrix around them under the action of a magnetic field are discussed.

The work is devoted to the study of the mechanical properties of porous ceramics based on diatomite, which has high porosity, adsorption capacity, weak thermal and acoustic conductivity, refractoriness and acid resistance. Based on the morphological analysis of the samples, the numerical value of the sample’s porosity was determined. The mechanical properties of the samples were determined by static and dynamic loading methods. The values of static and dynamic elastic moduli of the samples were experimentally measured. The research results showed that, for the material under consideration, at the initial stages of compression processes, the processes of elastic deformation are mainly realized with the subsequent transition to the region of plastic deformation. It was also found that for highly porous samples in the elastic deformation region, the manifestation of pressing processes is possible. In this work, the study of the dependence of the dynamic modulus of porous diatomite ceramics on porosity was carried out: a decrease in elastic moduli was recorded with an increase in the material porosity. A decrease in material porosity after deformation is found.

The work is focused on studying the relationship between dynamic Ed and static Es modules of elasticity of porous diatomite. A significant difference (10 times) between E-d and E-s which was discovered experimentally, was associated by the authors with the influence of the porosity value. The work examines various models of the dependence E-s = f (E-d), and it was established that for porous diatomite (with porosity P = 30-85%) nonlinear degree functions describe well the observed experimental dependence E-s = f (E-d).

Herein, a physical and mathematical model of the voltage−current characteristics of a p−n heterostructure with quantum wells (QWs) is prepared using the Sah−Noyce−Shockley (SNS) recombination mechanism to show the SNS recombination rate of the correction function of the distribution of QWs in the space charge region of diode configuration. A comparison of the model voltage−current characteristics (VCCs) with the experimental ones reveals their adequacy. The technological parameters of the structure of the VCC model are determined experimentally using a nondestructive capacitive approach for determining the impurity distribution profile in the active region of the diode structure with a profile depth resolution of up to 10 Å. The correction function in the expression of the recombination rate shows the possibility of determining the derivative of the VCCs of structures with QWs with a nonideality factor of up to 4.

In this work, a computerized measuring device is developed and created for non-destructive measurement of the concentration distribution of an electrically active impurity in p-n structures. The concentration distribution is measured by recording the parameters of the barrier capacity when a small two-frequency signal is exposed to the structure under the study. The device makes it possible to study the concentration profile of p-n structures in the area of the location of quantum wells with a depth resolution of up to 3-4 atomic layers in the range of changes in the width of the spatial charge region under the influence of a constant bias voltage. The measurement results are processed, and the measuring device is controlled by a microcontroller.

The article analyses the possibility of using elements of thermal memory to create a system that allows to perform calculations in memory. Such a computing system is built on devices that are used simultaneously for storing input data, performing a logical operation, and storing the output result. The authors conclude that it is possible to emulate this behaviour by using thermal memory elements with dielectric (SiO2) by a layer of thermal insulation. Special attention is paid to the logic gates of computing systems and their realisation on the basis of thermal memory elements. Simulation modelling of the work of such elements is carried out on the ANSYS Workbanch platform using the Transient Thermal module for non-stationary thermal calculations. On the basis of the modelling, the possibility of creating two basic logic gates “AND” and “OR” is established. The results can be used to create more integrated structures, such as artificial neural networks.