Journal articles on the topic 'Semiconductors – Impurity distribution'
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Yakovlev, G. E., D. S. Frolov, and V. I. Zubkov. "Diagnostics of semiconductor structures by electrochemical capacitance-voltage profiling technique." Industrial laboratory. Diagnostics of materials 87, no. 1 (January 19, 2021): 35–44. http://dx.doi.org/10.26896/1028-6861-2021-87-1-35-44.
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The properties of interfaces in the heterostructures which frequently govern their operation are of particular importance for the devices containing heterostructures as active elements. Any further improving of the characteristics of semiconductor devices is impossible without a detail analysis of the processes occurring at the interfaces of heterojunctions. At the same time, the results largely depend on the purity of the starting materials and the technology of layer manufacturing. Moreover, the requirements to the composition and distribution of the impurity steadily get stringent. Therefore, the requirements regarding the methods of the impurity control and carrier distribution also become tougher both in the stage of laboratory development of the structure and in various stages of manufacturing of semiconductor devices. Electrochemical capacitance-voltage profiling is distinguished among the methods of electrical diagnostics of semiconductors by the absence of special preparation of the structures and deposition of the contacts to perform measurements, thus providing for gaining information not only about the impurity distribution but also about the distribution of free carriers. The goal of this work is to perform precise measurements of the profiles of free carrier distribution in semiconductor structures of different types, and demonstrate the measuring capabilities of a modern technique for concentration distribution diagnostics, i.e., electrochemical capacitance-voltage profiling. The method allows verification of the layer thickness in semiconductor heterostructures and provide a useful and informative feedback to technologists. To increase the resolution of the method and broad up the range of available test frequencies, a standard electrochemical profiler has been modified. Mapping data for GaAs substrate structure, the profiles of the concentration distribution of the majority charge carriers in SiC structures, GaAs structure with a p – n junction, pHEMT heterostructure, GaN heterostructure with multiple quantum wells, and in a silicon-based solar cell heterostructure are presented. The obtained results can be used to analyze the physical properties and phenomena in semiconductor devices with quantum-sized layers, as well as to improve and refine the parameters of existing electronic devices.
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E SILVA, E. A. DE ANDRADA, and I. C. DA CUNHA LIMA. "DENSITY OF STATES AND CHARGE DISTRIBUTION IN LIGHTLY DOPED AND COMPENSATED QUANTUM WELL." Modern Physics Letters B 03, no. 11 (July 20, 1989): 815–19. http://dx.doi.org/10.1142/s021798498900128x.
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In this letter we use a Semi-Classical Impurity Band Model and obtain by Monte Carlo simulation the density of states (DOS) and the impurity charge distribution inside a quantum well (QW) of Ga 1−x Al x As/GaAs . We show the existence of a Coulomb gap as has been observed in bulk semiconductors. The DOS is not very sensitive to the QW width close to the Coulomb gap, at least in the range from 1 to 4 times the Bohr radius, and shows a behavior D(E)∝|E−EF| which indicates a two-dimensional signature. We show that the neutral donors concentrate in the center of the well according to a distribution whose width and decay rate depend on the compensation and impurity concentration respectively. Those effects are expected to be observed by infra-red absorption experiments and useful in device diagnosis.
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DZHUMANOV, S., U. T. KURBANOV, and A. KURMANTAYEV. "POSSIBLE QUANTITATIVE CRITERIA FOR THE MOTT AND ANDERSON TRANSITIONS IN DOPED UNCOMPENSATED SYSTEMS." International Journal of Modern Physics B 21, no. 02 (January 20, 2007): 169–78. http://dx.doi.org/10.1142/s0217979207036552.
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Metal-insulator transitions (MITs) in doped uncompensated systems are investigated in the Mott–Hubbard and Anderson impurity models by considering the intercarrier correlation and screening effect of carriers in the same hydrogenic impurity center, the formation of the superlattices with different coordination numbers (z=6, 8 and 12) and by studying the effect of randomness in impurity distribution. We have obtained simple and quite general criteria for the Mott and Anderson transitions and used these criteria to describe quantitatively the correlation and disorder-induced MITs in doped semiconductors and high-T c cuprates. We examine the validity of the obtained criteria for the Mott and Anderson MITs in these doped systems. It is found that the newly derived criteria for the Mott MIT are well satisfied in doped semiconductors, but they cannot be used to describe the observed MITs in the hole-doped high-T c cuprates, whereas the newly derived criteria for the Anderson MIT are applicable equally to describe the MITs observed both in doped semiconductors (at weak and intermediate disorders) and in doped cuprates (at intermediate and strong disorders). The new criteria for the Anderson MIT are extended to the polaronic systems in p-type cuprates. Our results are in quantitative agreement with the existing well-established experimental data and shed more light on the different types of MITs that occur in doped uncompensated semiconductors and cuprates.
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Wei-Hua, Wang, and Zou Liang-Jian. "Electronic States and Spatial Charge Distribution of Single Mn Impurity in Diluted Magnetic Semiconductors." Chinese Physics Letters 23, no. 6 (May 30, 2006): 1588–91. http://dx.doi.org/10.1088/0256-307x/23/6/064.
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Muraguchi, Masakazu, Ryuho Nakaya, Souma Kawahara, Yoshitaka Itoh, and Tota Suko. "Investigation of features for prediction modeling of nanoscale conduction with time-dependent calculation of electron wave packet." Japanese Journal of Applied Physics 61, no. 4 (March 16, 2022): 044001. http://dx.doi.org/10.35848/1347-4065/ac45a5.
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Abstract A model to predict the electron transmission probability from the random impurity distribution in a two-dimensional nanowire system by combining the time evolution of the electron wave function and machine learning is proposed. We have shown that the intermediate state of the time evolution calculation is advantageous for efficient modeling by machine learning. The features for machine learning are extracted by analyzing the time variation of the electron density distribution using time evolution calculations. Consequently, the prediction error of the model is improved by performing machine learning based on the features. The proposed method provides a useful perspective for analyzing the motion of electrons in nanoscale semiconductors.
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Pennycook, S. J. "Electron Channeling Analysis and Z-C0ntrast Imaging of Dopants in Semiconductors." Proceedings, annual meeting, Electron Microscopy Society of America 43 (August 1985): 296–99. http://dx.doi.org/10.1017/s0424820100118369.
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The determination of dopant distribution and lattice location are key elements in the characterization of ion-implanted, thermally processed semiconductors. We present here two analytical techniques for this purpose. The first is a channeling technique for the determination of substitutional fractions of dopants or impurities in any crystal structure, and the second is a means for imaging and elemental mapping of heavy elements in light materials, even if they are in solution.Atom Location by Electron Channeling AnalysisIt has only recently been realized that the orientation dependence of characteristic x-ray emission close to a Bragg reflection, long regarded as a hindrance to accurate microanalysis, can form the basis of a powerful lattice location technique. The first studies of this kind located trace elements in layer structure minerals, where it was known that the only possible sites for the impurity lay within the layer planes A and/or B. These restraints exclude many materials and here a generalization to any crystal structure is described.
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Poklonski, N. A., S. A. Vyrko, A. I. Kovalev, I. I. Anikeev, and N. I. Gorbachuk. "Design of Peltier Element Based on Semiconductors with Hopping Electron Transfer via Defects." Devices and Methods of Measurements 12, no. 1 (March 19, 2021): 13–22. http://dx.doi.org/10.21122/2220-9506-2021-12-1-13-22.
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The study of thermoelectric properties of crystalline semiconductors with structural defects is of practical interest in the development of radiation-resistant Peltier elements. In this case, the spectrum of energy levels of hydrogen-like impurities and intrinsic point defects in the band gap (energy gap) of crystal plays an important role.The purpose of this work is to analyze the features of the single-electron band model of semiconductors with hopping electron migration both via atoms of hydrogen-like impurities and via their own point triplecharged intrinsic defects in the c- and v-bands, as well as to search for the possibility of their use in the Peltier element in the temperature range, when the transitions of electrons and holes from impurity atoms and/or intrinsic defects to the c- and v-bands can be neglected.For Peltier elements with electron hopping migration we propose: (i) an h-diode containing |d1)and |d2)-regions with hydrogen-like donors of two types in the charge states (0) and (+1) and compensating them hydrogen-like acceptors in the charge state (−1); (ii) a homogeneous semiconductor containing intrinsic t-defects in the charge states (−1, 0, +1), as well as ions of donors and acceptors to control the distribution of t-defects over the charge states. The band diagrams of the proposed Peltier elements in equilibrium and upon excitation of a stationary hopping electric current are analyzed.A model of the h-diode containing hydrogen-like donors of two types |d1) and |d2) with hopping migration of electrons between them for 50 % compensation by acceptors is considered. It is shown that in the case of the reverse (forward) electrical bias of the diode, the cooling (heating) of the region of the electric double layer between |d1)and |d2)-regions is possible.A Peltier element based on a semiconductor with point t-defects is considered. It is assumed that the temperature and the concentration of ions of hydrogen-like acceptors and donors are to assure all t-defects to be in the charge state (0). It is shown that in such an element it is possible to cool down the metal-semiconductor contact under a negative electric potential and to heat up the opposite contact under a positive potential.
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Portavoce, Alain, Khalid Hoummada, and Lee Chow. "Coupling Secondary Ion Mass Spectrometry and Atom Probe Tomography for Atomic Diffusion and Segregation Measurements." Microscopy and Microanalysis 25, no. 2 (January 30, 2019): 517–23. http://dx.doi.org/10.1017/s1431927618015623.
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AbstractFor a long time, secondary ion mass spectrometry (SIMS) was the only technique allowing impurity concentrations below 1 at% to be precisely measured in a sample with a depth resolution of few nanometers. For example, SIMS is the classical technique used in microelectronics to study dopant distribution in semiconductors and became, after radiotracers were forsaken, the principal tool used for atomic transport characterization (diffusion coefficient measurements). Due to the lack of other equivalent techniques, sometimes SIMS could be used erroneously, especially when the analyzed solute atoms formed clusters, or for interfacial concentration measurements (segregation coefficient measurements) for example. Today, concentration profiles measured by atom probe tomography (APT) can be compared to SIMS profiles and allow the accuracy of SIMS measurements to be better evaluated. However, APT measurements can also carry artifacts and limitations that can be investigated by SIMS. After a summary of SIMS and APT measurement advantages and disadvantages, the complementarity of these two techniques is discussed, particularly in the case of experiments aiming to measure diffusion and segregation coefficients.
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Westwood, A. D. "Application of AEM to chemical and structural characterization of the AlN-Al2O3 and AlN-Al2O3-SiO2 Systems." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 318–19. http://dx.doi.org/10.1017/s0424820100137963.
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The thermal, electronic and mechanical properties of aluminum nitride (A1N) make it an attractive material to a number of technologically important areas; microelectronic packaging, high temperature semiconductors, opto-electronic and piezoelectric devices and structural ceramics. It is well established that the concentration and distribution of impurities can control the macroscopic properties of materials. A1N is a classic example, with oxygen (O) being the dominant controlling impurity. The role of O in point defect formation and its detrimental effect on thermal conductivity was first documented by Slack. Oxygen has subsequently been shown to cause the formation of two-dimensional extended defects of which two variants exist, planar and curved. Both defects have been identified as O-rich inversion domain boundaries (IDB´s) (Fig.l). Because of the controlling influence that O has on thermal conductivity, it is important to fully understand the defect structures and chemistries that exist as a result of O incorporation. A1N-A12O3 is a prototype system for understanding the role that non-stoichiometry (impurities) plays in IDB formation.
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Lei, X. L., and N. J. M. Horing. "Balance-Equation Approach to Hot-Carrier Transport in Semiconductors." International Journal of Modern Physics B 06, no. 07 (April 10, 1992): 805–936. http://dx.doi.org/10.1142/s0217979292000505.
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The balance-equation approach to nonlinear hot-carrier transport theory, formulated by Lei and Ting (1984), is addressed in this comprehensive review. A central feature is the role of strong electron-electron interactions in promoting rapid thermalization about the drifted transport state and the concomitant substantial simplification of the transport theory. This physical feature is embodied in the initial density matrix chosen to represent the unperturbed carrier system. Force and energy balance equations are formulated for the dc steady state, ac dynamic and transient cases of charge conduction, including memory effects. The scattering mechanisms include impurity and phonon interactions along with dynamic nonlocal screening effects due to carrier-carrier interactions. Both linear and nonlinear resistivities are discussed in the degenerate and nondegenerate statistical regimes. Interesting phenomena such as electron cooling and thermal noise and diffusion are discussed as well. Semiconductor microstructure transport is described for both linear and nonlinear hot carrier conduction. In this connection, quasi-2D-systems, heterojunctions, and quantum well superlattices are treated with attention to steady state, transient and high frequency transport, including, for example, superlattice plasmon resonance structure. Type-II superlattice transport is reviewed as well as type-I, and electron-hole drag is treated in conjunction with negative minority electron mobility in a quantum well. Multivalley semiconductors are discussed in some detail. Furthermore, attention is also focused on the center-of-mass velocity fluctuation, Langevin-type equation and thermal noise and diffusion for microstructures and multivalley systems. A number of particularly important phenomena are examined from the balance-equation point of view, such as nonequilibrium phonons, higher order scattering effects and weak localization, hydrodynamic equations for weakly nonuniform systems, and the intracollisional field effect. Alternative formulations and interpretations of the balance-equation approach are reviewed. The distinction between this many-particle, isothermal, balance-equation theory and the noninteracting (single-particle) adiabatic transport theory is discussed to clarify issues subject to controversy in the literature. Finally, we give a brief review of recent developments in the balance-equation approach: investigation of the distribution function in balance-equation theory, improved calculations for GaAs/AlGaAs heterojunctions, extension of the balance equations to an abitrary energy band and recent work on superlattice miniband transport.
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Muratov, Temur T. "Statistical approach to the process of tunnel ionisation of impurity centres near the heterointerface." Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 23, no. 4 (November 24, 2021): 529–34. http://dx.doi.org/10.17308/kcmf.2021.23/3671.
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To date, the processes of tunnel ionisation of impurities near the interface between two different semiconductors have been comprehensively studied. The most important parameters of the contact electron states of impurities have been determined. However, the calculated expressions for these parameters have been of local nature, as applied to individual impurities. Meanwhile, it is easy to understand that a number of processes, such as the flow of charge carriers and their diffusion through a heterojunction, are clearly statistical in nature. The same applies to the processes of tunnel ionisation of shallow and/or deep impurities near the interface. A statistical approach to the calculation of the parameters of tunnel ionisation of impurities broadens the opportunities for obtaining fundamental information regarding surface electronstates.The aim of this work was to use a statistical approach to study the effect of the heterointerface on the energy spectrum of shallow and deep centres. For this purpose, the expansion of the reflected quasi-classical wave function within the complete system of spherical harmonics and the subsequent extraction of the zero harmonic amplitude (s-component) was used to estimate the minimum distance from the impurity to the heterobarrier and to specify the limitations of the applicability of the results obtained in other works. The article analyses the conditions of the quasi-classical approximation which are used to estimate the order of the value for the minimum height of the potential barrier (pit).This work (with due consideration given to the minimum distance estimate) presents averaged formulas obtained for the energy shift of the ground state and the lifetime of the quasi-stationary state depending on the distance from the heterobarrier. Some qualitatively new considerations can also be found in the article. The distribution of impurity centres near the heterobarrier is assumed to be uniform. The article discusses the role of electron transitions in causing the buffer field effect for both shallow and deep centres. The focus of the article is on the estimates of various physical parameters characterising electron transitions near the heterobarrier.
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Bublik, Vladimir T., Marina I. Voronova, and Kirill D. Shcherbachev. "Capabilities of X-ray diffuse scattering method for study of microdefects in semiconductor crystals." Modern Electronic Materials 4, no. 4 (December 1, 2018): 125–34. http://dx.doi.org/10.3897/j.moem.4.4.47197.
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The capabilities of X-ray diffuse scattering (XRDS) method for the study of microdefects in semiconductor crystals have been overviewed. Analysis of the results has shown that the XRDS method is a highly sensitive and information valuable tool for studying early stages of solid solution decomposition in semiconductors. A review of the results relating to the methodological aspect has shown that the most consistent approach is a combination of XRDS with precision lattice parameter measurements. It allows one to detect decomposition stages that cannot be visualized using transmission electron microscopy (TEM) and moreover to draw conclusions as to microdefect formation mechanisms. TEM-invisible defects that are coherent with the matrix and have smeared boundaries with low displacement field gradients may form due to transmutation doping as a result of neutron irradiation and relaxation of disordered regions accompanied by redistribution of point defects and annihilation of interstitial defects and vacancies. For GaP and InP examples, a structural microdefect formation mechanism has been revealed associated with the interaction of defects forming during the decomposition and residual intrinsic defects. Analysis of XRDS intensity distribution around the reciprocal lattice site and the related evolution of lattice constant allows detecting different decomposition stages: first, the formation of a solution of Frenkel pairs in which concentration fluctuations develop, then the formation of matrix-coherent microdefects and finally coherency violation and the formation of defects with sharp boundaries. Fundamentally, the latter defects can be precipitating particles. Study of the evolution of diffuse scattering iso-intensity curves in GaP, GaAs(Si) and Si(O) has allowed tracing the evolution of microdefects from matrix-coherent ones to microdefects with smeared coherency resulting from microdefect growth during the decomposition of non-stoichiometric solid solutions heavily supersaturated with intrinsic (or impurity) components.
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Lauhon, Lincoln J., Praneet Adusumilli, Paul Ronsheim, Philip L. Flaitz, and Dan Lawrence. "Atom-Probe Tomography of Semiconductor Materials and Device Structures." MRS Bulletin 34, no. 10 (October 2009): 738–43. http://dx.doi.org/10.1557/mrs2009.248.
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AbstractThe development of laser-assisted atom-probe tomography (APT) analysis and new sample preparation approaches have led to significant advances in the characterization of semiconductor materials and device structures by APT. The high chemical sensitivity and three-dimensional spatial resolution of APT makes it uniquely capable of addressing challenges resulting from the continued shrinking of semiconductor device dimensions, the integration of new materials and interfaces, and the optimization of evolving fabrication processes. Particularly pressing concerns include the variability in device performance due to discrete impurity atom distributions, the phase and interface stability in contacts and gate dielectrics, and the validation of simulations of impurity diffusion. This overview of APT of semiconductors features research on metal-silicide contact formation and phase control, silicon field-effect transistors, and silicon and germanium nanowires. Work on silicide contacts to silicon is reviewed to demonstrate impurity characterization in small volumes and indicate how APT can facilitate defect mitigation and process optimization. Impurity contour analysis of a pFET semiconductor demonstrates the site-specificity that is achievable with current APTs and highlights complex device challenges that can be uniquely addressed. Finally, research on semiconducting nanowires and nanowire heterostructures demonstrates the potential for analysis of materials derived from bottom-up synthesis methods.
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Murzin, Serguei P. "Improvement of Thermochemical Processes of Laser-Matter Interaction and Optical Systems for Wavefront Shaping." Applied Sciences 12, no. 23 (November 27, 2022): 12133. http://dx.doi.org/10.3390/app122312133.
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Laser thermochemical processes of metal surface oxidation are promising for creating new advanced technologies to meet the growing needs of opto- and micro-electronics, photonics, catalysis, sensorics and other high-tech industries. The features of thermochemical processes of laser-matter interaction occurring in matter under exposure to intense light flows and optical systems for controlling the irradiance and wavefront spatial distribution were reviewed. The laser beam offers the possibility of good focusing, which allows us to conduct chemical reactions, including the heterogeneous oxidation of metals, locally, with high spatial resolution. In this case, the absorption mechanisms of the laser beam vary for metals and for oxides, resulting from a thermochemical reaction and represent semiconductors. For semiconductors, the intrinsic, intraband, impurity, or lattice absorption takes place. The morphology of a metal surface also influences its optical absorption capacity. The improvement of beam shaping systems with elements of computer optics, namely diffractive freeform optics, provides an opportunity for an efficient control of chemical processes by achieving the desired redistribution of the laser beam power density. Laser thermochemical processes of the formation of quasi-one-dimensional nanostructured metal oxides are of great interest for advanced research and for a wide range of applications. A special feature of these processes is that, in the case of a frequency-modulated laser beam the synergy between the heat associated effects of the laser pulses and the laser-induced vibrations allows for a significant increase in the diffusion coefficient, which is stimulated by the non-stationary stress-strain state of the material. Ensuring the means of control over the thermochemical reaction in local sections of the laser exposure zone is an issue that can be solved by adapting the shape of the laser beam by the diffractive freeform optics. The gained knowledge contributes as a foundation for new photonic technologies oriented on the formation of nanostructured metal oxides, involving control over the morphology of the synthesized structures.
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Kondrik, A. I., and G. P. Kovtun. "Influence of impurities and structural defects on electrophysical and detector properties of CdTe and CdZnTe." Технология и конструирование в электронной аппаратуре, no. 5-6 (2019): 43–50. http://dx.doi.org/10.15222/tkea2019.5-6.43.
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Solid-state ionizing radiation detectors based on high-resistance semiconductors can be used to monitor the safety of nuclear reactors. High-resistance CdTe and CdZnTe have very good electrophysical and detector properties. The objective of this study was to use computer simulation to determine how impurities and structural defects, as well as their clusters, affect electrophysical and detector properties of Cd1-xZnxTe (0≤x≤0.3). The calculations were based on well-tested models, the reliability of which was confirmed when comparing simulation results with well-known experimental data. It has been established that deep donors with energy levels near the middle of the band gap considerably extend the area of the high-resistance state of CdTe and CdZnTe, which is suitable for the creation of radiation detectors. The capture and recombination of non-equilibrium charge carriers occurs at the deep levels of cadmium vacancies owing to the influence of Ti, V, Ge, Ni, and Sn impurities. For this reason, such impurities are considered to be harmful, noticeably reducing the efficiency of charge collection η in CdTe and CdZnTe detectors. The decrease of electron mobility in CdTe and CdZnTe can be caused by the distribution heterogeneity of impurities (impurity clusters).When concentration of harmful impurities Ti, V, Ni, Sn, Ge does not exceed the content of the "background", provided that the impurities are distributed over the crystal uniformly, it is possible to obtain high-resistance CdZnTe of an acceptable detector quality. The obtained results could help determining conditions for producing CdTe and CdZnTe materials of high detector quality.
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Krayovskyy, Volodymyr, Volodymyr Pashkevych, Andriy Horpenuk, Volodymyr Romaka, Yurii Stadnyk, Lyubov Romaka, and Andriy Horyn. "STUDY OF THERMOMETRIC MATERIAL Er1-xScxNiSb. II. EXPERIMENTAL RESULTS." Measuring Equipment and Metrology 82, no. 3 (2021): 5–11. http://dx.doi.org/10.23939/istcmtm2021.03.005.
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The results of a comprehensive study of the crystal and electronic structures, kinetic and energetic performances of the semiconductor thermometric material Er1-xScxNiSb, (x=0–0.1) are presented. Microprobe analysis of the concentration of atoms on the surface of Er1-xScxNiSb samples established their correspondence to the initial compositions of the charge, and the diffractograms of the samples are indexed in the structural type of MgAgAs. Because the atomic radius Sc (rSc=0.164 nm) is smaller than that of Er (rEr=0.176 nm), it is logical to reduce the values of the unit cell's period a(x) Er1-xScxNiSb, which correlate with the results of mathematical modeling. The temperature dependences of the resistivity ln(ρ(1/T)) contain high- and low-temperature activation regions, which are specific for semiconductors and indicate the location of the Fermi level in the bandgap, and positive values of the thermopower coefficient a(x, T) specify its position – near the valence band . This result does not agree with the results of modeling the electronic structure for its ordered version. The presence of a low-temperature activation region on the ln(ρ(1/T)) p-ErNiSb dependence with an activation energy =0.4 meV indicates the compensation of the sample provided by acceptors and donors of unknown origin. A decrease in the values of the resistivity ρ(x, T) and the thermopower coefficient a(x, T) points to an increase in the concentration of holes in p-Er1- xScxNiSb in the area of concentrations x=0–0.03. This is possible in a p-type semiconductor only by increasing the concentration of the main current carriers, which are holes. The fact of increasing the concentration of acceptors in Er1-xScxNiSb at insignificant concentrations of impurity atoms is also indicated by the nature of the change in the values of the activation energy of holes from the Fermi level to the valence band . Consequently, if in p-ErNiSb the Fermi level was at a distance of 45.4 meV from the level of the valence band , then at the concentration Er1-xScxNiSb, x=0.01, the Fermi level shifted towards the valence band and was located at a distance of 13.6. Since the Fermi level reflects the ratio of ionized acceptors and donors in the semiconductor, its movement by x=0.01 to the valence band is possible either with an increase in the number of acceptors or a rapid decrease in the concentration of ionized donors. At even higher concentrations of Sc impurity in p-Er1-xScxNiSb, x≥0.03, low-temperature activation sites appear on the ln(ρ(1/T)) dependences, which is a sign of compensation and evidence of the simultaneous generation of acceptor and donor structural defects in the crystal nature. This is also indicated by the change in the position of the Fermi level in the bandgap of the semiconductor Er1-xScxNiSb, which is almost linearly removed from the level of the valence band : (x=0.05)=58.6 meV and (x=0.10)=88.1 meV. Such a movement of the Fermi level during doping of a p-type semiconductor is possible only if donors of unknown origin are generated. For a p-type semiconductor, this is possible only if the concentration of the main current carriers, which are free holes, is reduced, and donors are generated that compensate for the acceptor states. This conclusion is also confirmed by the behavior of the thermopower coefficient a(x, T) at concentrations x≥0.03. The results of structural, kinetic, and energy studies of the thermometric material Er1-xScxNiSb allow us to speak about a complex mechanism of simultaneous generation of structural defects of acceptor and donor nature. However, the obtained array of experimental information does not allow us to unambiguously prove the existence of a mechanism for generating donors and acceptors. The research article offers a solution to this problem. Having the experimental results of the drift rate of the Fermi level as the activation energy (x) from the Fermi level to the valence band by calculating the distribution of the density of electronic states (DOS) sought the degree of compensation, which sets the direction and velocity of the Fermi level as close as possible to the experimental results. DOS calculations are performed for all variants of the location of atoms in the nodes of the unit cell, and the degree of occupancy of all positions by their own and/or foreign atoms. It turned out that for ErNiSb the most acceptable option is one that assumes the presence of vacancies in positions 4a and 4c of the Er and Ni atoms, respectively. Moreover, the number of vacancies in the position Er (4a) is twice less than the number of vacancies in the position Ni (4c). This proportion is maintained for Er1-xScxNiSb. Vacancies in the positions of Er (4a) and Ni (4c) atoms Er1-xScxNiSb are structural defects of acceptor nature, which generate two acceptor zones and in the semiconductor. The introduction of impurity Sc atoms into the ErNiSb structure by substituting Er atoms in position 4a is also accompanied by the occupation of vacancies by Sc atoms and a reduction in their number. Occupying a vacancy, the Sc atom participates in the formation of the valence band and the conduction band of the semiconductor Er1-xScxNiSb, acting as a source of free electrons. We can also assume that the introduction of Sc atoms into the structure of the compound ErNiSb is accompanied by a process of ordering the structure of Er1-xScxNiSb and Ni atoms occupy vacancies in position 4c. This process also, however, 2 times slower, leads to a decrease in the concentration of structural defects of acceptor nature. In this case, Ni, giving valence electrons, now act as donors.
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REKHA, B., and K. NAVANEETHAKRISHNAN. "CARRIER MOBILITY IN A SEMICONDUCTOR QUANTUM WELL WIRE–EFFECTS OF EXTERNAL PERTURBATIONS." International Journal of Modern Physics B 20, no. 01 (January 10, 2006): 49–60. http://dx.doi.org/10.1142/s0217979206033048.
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Carrier mobility in a narrow GaAs semiconductor quantum well wire embedded in the GaAlAs matrix is investigated using a simple model developed by Lee and Spector. Five different screening functions with three different impurity distributions are used in the calculations. The results show that (i) the choice of the screening function is important as the mobility values vary by two orders of magnitude, and (ii) the mobility values not only depend on the impurity distribution but also vary differently with the wire radius. While hydrostatic pressure reduces the mobility values, temperature increases the values. The polaronic effect decreases the mobility values irrespective of temperature and pressure, the maximum contribution being 9%.
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Volkov, P. K., B. G. Zakharov, and Yu A. Serebryakov. "Convection in melts and impurity distribution in semiconductor crystals." Crystallography Reports 45, no. 5 (September 2000): 862–70. http://dx.doi.org/10.1134/1.1312937.
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Hayakawa, Y., Y. Saitou, Y. Sugimoto, and M. Kumagawa. "Analysis of impurity concentration distributions in pulled semiconductor crystals." Journal of Electronic Materials 19, no. 2 (February 1990): 145–49. http://dx.doi.org/10.1007/bf02651739.
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Bondarenko, V. B., A. V. Filimonov, and E. Yu Koroleva. "The Schottky barrier at homogeneous impurity distribution in a semiconductor." Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques 4, no. 5 (October 2010): 859–61. http://dx.doi.org/10.1134/s1027451010050290.
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Ilicheva, Tatiana, and Eugeny Panyutin. "Integrated technologies and the problem of creation of large-area silicone carbide devices for high-power converters." MATEC Web of Conferences 239 (2018): 01019. http://dx.doi.org/10.1051/matecconf/201823901019.
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We consider limitations typical for semiconductor devices of up-to-date converter equipment based on silicon and silicone technologies. The reasons for processing complexities in creating the hardware components of heavy-current devices based on wide-band-gap semiconductors are analyzed. Possible approach to production of large area SiC-diodes and thyristors is formulated, which at post-processing stage allows performing modification of their voltage-current characteristics (VCC) and increasing in its non-linearity coefficient. Based on the concept of integrated power devices containing mesa-elements with VCC with random parameters, the possibility of sequential automated exclusion of those single “non-standard” micro-devices to adversely impact on general voltage-current characteristics of an array is considered. Algorithm is briefly described, and computer modelling of transformation of the reverse branch of integrated VCC occurring in the course of such modification is provided, which made it possible to establish relationship between the typical probability distributions of impurity (including in the presence of dislocations) and certain features of final VCC.
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Ромака, В. А., P. F. Rogl, D. Frushart, and D. Kaczorowski. "Механизм генерирования донорно-акцепторных пар при сильном легировании n-ZrNiSn акцепторной примесью Ga." Физика и техника полупроводников 52, no. 3 (2018): 311. http://dx.doi.org/10.21883/ftp.2018.03.45614.8573.
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AbstractThe nature of the mechanism of the simultaneous generation of donor–acceptor pairs under heavy doping of n -ZrNiSn intermetallic semiconductor with the Ga acceptor impurity is established. Such spatial arrangement in the crystal lattice of ZrNiSn_1– x Ga_ x is found when the rate of movement of the Fermi level εF found from calculations of the density distribution of electron states coincides with that experimentally established from dependences lnρ(1/ T ). It is shown that when the Ga impurity atom (4 s ^24 p ^1) occupies the 4 b sites of Sn atoms (5 s ^25 p ^2), structural defects of both acceptor nature and donor nature in the form of vacancies in the 4 b site are simultaneously generated. The results are discussed in the scope of the Shklovskii–Efros model of a heavily doped and compensated semiconductor.
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Watling, J. R., J. R. Barker, and A. Asenov. "Soft Sphere Model for Electron Correlation and Scattering in the Atomistic Modelling of Semiconductor Devices." VLSI Design 13, no. 1-4 (January 1, 2001): 441–46. http://dx.doi.org/10.1155/2001/67156.
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As MOSFET devices within the deep sub-micron regime are modelled, it is no longer feasible to represent the charged dopants by a continuous charge distribution. In this regime an ensemble of devices, each with different spatial distributions and the number of dopants, must be modelled. However, it is computationally prohibitive to solve for the full Coulomb interaction required for particle simulators, especially for an ensemble of devices. To address this point, the paper focuses on the issue of modelling the dynamics in the presence of discrete carrier–carrier scattering and carrier-fixed impurity scattering which is suitable for efficient simulations of large ensembles of devices.
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Bondarenko, V. B., S. N. Davydov, and A. V. Filimonov. "Inherent potential inhomogeneity on the semiconductor surface for equilibrium impurity distribution." Semiconductors 44, no. 1 (January 2010): 41–44. http://dx.doi.org/10.1134/s1063782610010069.
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Zhao, Zhi Huan, Zhi Bin Zhao, Ming Ming Jiang, Chuan Zhong Chen, Wei Hai Song, Li Zhang, Li Li Liu, and Hui Jun Yu. "The Distribution Trend of Boron Atoms in Semiconductor Silicon under High Temperature." Key Engineering Materials 871 (January 2021): 243–47. http://dx.doi.org/10.4028/www.scientific.net/kem.871.243.
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The ProENGINEER software is used to build a geometric model for the whole process cavity and internal structure and conduct the internal dynamic simulation of cavity with different diffusion temperatures of 1,000°C, 1,050°C, 1,100°C and 1,150°C, and different diffusion time of 5 min, 10 min, 15 min and 20 min. Analyze the process control indexes by combining with specific thermal diffusion test, and study the relationship between hydrodynamic parameters and diffusion uniformity, Comprehensively investigate the effects of the diffusion temperature and diffusion time on doping, achieving the requirements of impurity distribution in materials.
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Sato, Michihiro, and Yosuke Takahashi. "Simulation of Dislocation Accumulation in Impurity Doped-ULSI Cells and Electric Characteristic Evaluations." International Journal of Automation Technology 10, no. 2 (March 4, 2016): 195–200. http://dx.doi.org/10.20965/ijat.2016.p0195.
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The performance of semiconductor devices has improved on introducing increasing refinements to the structures of these devices. This has created various problems at the atomic level. In particular, the presence of dislocations, a type of crystallographic defect, within semiconductor devices poses a major problem. Dislocations accumulated within the device obstruct the movement of electrons and adversely affect the electrical characteristics of the device. However, previous investigations have not sufficiently clarified the relationship between accumulated dislocations and the electrical characteristics of a semiconductor. In this study, we focus on dislocations produced in the fabrication of an impurity-doped ultra-large-scale integration (ULSI) device and, based on a crystal plasticity analysis, perform a simulation of the accumulation of dislocations within the device during the cooling process. We establish an analytical system by which the obtained information on dislocations is applied to a device simulator, in order to evaluate the electrical characteristics by considering the accumulation of dislocations. We investigate the effects that dislocation density and density distribution have on the characteristic current-voltage curve of the device.
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Марков, О. И. "О распределении носителей заряда в ветви термоэлектрического охладителя." Журнал технической физики 91, no. 11 (2021): 1722. http://dx.doi.org/10.21883/jtf.2021.11.51534.70-21.
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The simulation of energy conversion in the branches of a thermoelectric cooler is carried out. The influence of various distributions of the active impurity along the branch of the thermoelement on its efficiency in the mode of maximum temperature drop is considered. The calculation is carried out within the framework of a two-band standard model of the band structure of a semiconductor for non-degenerate charge carriers. The Thomson effect was not taken into account.
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Yanchev, I. Y., and A. D. Anguelov. "Impurity potential distribution and density of states in a heavily doped, slightly compensated semiconductor." Philosophical Magazine B 72, no. 5 (November 1995): 475–87. http://dx.doi.org/10.1080/13642819508239099.
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Mantsevich, V. N., and N. S. Maslova. "Spatial distribution of local density of states in vicinity of impurity on semiconductor surface." JETP Letters 89, no. 12 (August 2009): 609–13. http://dx.doi.org/10.1134/s0021364009120042.
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Krayovskyy, Volodymyr, Volodymyr Pashkevych, Mariya Rokomanyuk, Petro Haranuk, Volodymyr Romaka, Yuriy Stadnyk, Lyubov Romaka, and Andriy Horyn. "KINETIC AND ENERGETIC PERFORMANCES OF THERMOMETRIC MATERIAL TiCo1-xMnxSb: MODELLING AND EXPERIMENT." Measuring Equipment and Metrology 82, no. 1 (2021): 19–25. http://dx.doi.org/10.23939/istcmtm2021.01.019.
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The results of a complex study of the semiconductor thermometric material TiСo1-xMnxSb, х=0.01–0.10, for the producing of sensitive elements of thermoelectric and electro resistive sensors are presented. Microprobe analysis of the concentration of atoms on the surface of TiСo1-xMnxSb samples established their correspondence to the initial compositions of the charge, and X-ray phase analysis showed the absence of traces of extraneous phases on their diffractograms. The produced structural studies of the thermometric material TiСo1-xMnxSb allow to speak about the ordering of its crystal structure, and the substitution of Co atoms on Mn at the 4c position generate structural defects of acceptor nature. The obtained results testify to the homogeneity of the samples and their suitability for the study of electrokinetic performances and the manufacture of sensitive elements of thermocouples. Modeling of structural, electrokinetic and energetic performances of TiСo1-xMnxSb, х=0.01–0.10, for different variants of spatial arrangement of atoms is performed. To model energetic and kinetic performances, particularly the behavior of the Fermi level, the band gap, the density of states (DOS) distribution was calculated for an ordered variant of the structure in which Co atoms at position 4c are replaced by Mn atoms. Substitution of Co atoms (3d74s2) by Mn (3d54s2) generates structural defects of acceptor nature in the TiСo1-xMnxSb semiconductor (the Mn atom contains fewer 3d- electrons than Co). This, at the lowest concentrations of impurity atoms Mn, leads to the movement of the Fermi level from the conduction band to the depth of the band gap. In a semiconductor with the composition TiCo0.99Mn0.01Sb, the Fermi level is located in the middle of the band gap, indicating its maximum compensation when the concentrations of ionized acceptors and donors are close. At higher concentrations of impurity Mn atoms, the number of generated acceptors will exceed the concentration of donors, and the concentration of free holes will exceed the concentration of electrons. Under these conditions, the Fermi level approach, and then the level of the valence band TiСo1-xMnxSb cross: the dielectric-metal conductivity transition take place. The presence of a high-temperature activation region on the temperature dependence of the resistivity ln(ρ(1/T)) TiСo1‑xMnxSb at the lowest concentration of impurity atoms Mn, х=001, indicates the location of the Fermi level in the band gap of the semiconductor thermopower coefficient α(Т,х) at these temperatures specify its position - at a distance of ~ 6 meV from the level of the conduction band . In this case, electrons are the main carriers of current. The absence of a low-temperature activation region on this dependence indicates the absence of the jumping mechanism conductivity. Negative values of the thermopower coefficient α(Т,х) TiСo0,99Mn0,01Sb at all temperatures, when according to DOS calculations the concentrations of acceptors and donors are close, and the semiconductor is maximally compensated, can be explained by the higher concentration of uncontrolled donors. However, even at higher concentrations of impurity Mn atoms in TiСo0,98Mn0,02Sb, the sign of the thermopower coefficient α(Т,х) remains negative, but the value of resistivity ρ(х,Т) increases rapidly, and the Fermi level deepens into the forbidden zone at a distance of ~ 30 meV. The rapid increase in the values of the resistivity ρ(х,Т) in the region of concentrations х=0.01–0.02 shows that acceptors are generated in the TiСo1-xMnxSb semiconductor when Co atoms are replaced by Mn, which capture free electrons, reducing their concentration. However, negative values of the thermopower coefficient α(Т,х) are evidence that either the semiconductor has a significant concentration of donors, which is greater than the number of introduced acceptors (х=0.02), or the crystal simultaneously generates defects of acceptor and donor nature. The obtained result does not agree with the calculations of the electronic structure of the TiСo1-xMnxSb semiconductor. It is concluded that more complex structural changes occur in the semiconductor than the linear substitution of Co atoms by Mn, which simultaneously generate structural defects of acceptor and donor nature by different mechanisms, but the concentration of donors exceeds the concentration of generated acceptors. Based on a comprehensive study of the electronic structure, kinetic and energetic performances of the thermosensitive material TiСo1-xMnxSb, it is shown that the introduction of impurity Mn atoms into TiCoSb can simultaneously generate in the semiconductor an acceptor zone (substitution of Co atoms for Mn) and donor zones and of different nature. The ratio of the concentrations of ionized acceptors and donors generated in TiСo1-xMnxSb will determine the position of the Fermi level and the mechanisms of electrical conductivity. However, this issue requires additional research, in particular structural and modeling of the electronic structure of a semiconductor solid solution under different conditions of entry into the structure of impurity Mn atoms. The investigated solid solution TiСo1-xMnxSb is a promising thermometric material.
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Belmonte, Thierry, Cédric Noël, and Hiba Kabbara. "(Invited) Role of Trace Impurities in Microwave-Excited Atmospheric Pressure Plasmas: Application to 3D Nano-Printing." ECS Meeting Abstracts MA2022-02, no. 19 (October 9, 2022): 885. http://dx.doi.org/10.1149/ma2022-0219885mtgabs.
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Because rare gases like helium, neon or argon have first-excited levels at high energy (respectively 19.8, 16,62 and 11.5 eV), impurities with much lower energy levels are more easily excited. Thus, if their concentrations are high enough (hundreds of ppm or more), these impurities drive the behavior of the discharge, leading for instance to emission spectra where no lines of rare gas are visible. Modelling these discharges is a challenge because of the complexity of the chemical behavior of these trace elements. In microwave discharges, several problems arise among which one finds the role of electron-electron collisions, super-elastic collisions and the possible non-local heating of the electron energy distribution function. Based on a collisional–radiative model proposed to describe the behavior of a helium plasma sustained in a resonant cavity at atmospheric pressure, we will discussed these different aspects. The role of impurities will be described next. The level of dry air used as impurity typically varies from 0 to 1500 ppm, which corresponds to the most commonly encountered range in atmospheric pressure discharge experiments. Results clearly show that the plasma chemistry and consequently the discharge evolution is highly affected by the concentration level of impurities (from tens of thousands of ppm) in the mixture. Next, the use of these plasmas for 3D-nanoprinting will be detailed. This technology, named DISCRIBE, might be used for drawing electrical contacts, building pillars as part of metasurfaces or even creating 3D parts of clocks in watchmaking industry. A plasma-assisted printer, operated at atmospheric pressure, was developed to write patterns with sub-micrometric resolution. A reactive gas is injected through a needle within an atmospheric argon microwave plasma. Forming sub-micrometric needles (down to 100 nm in diameter) by pulling glass capillaries heated locally by laser is simple as this technology is readily available in the medical field. By plasma-enhanced chemical vapor deposition, a coating is formed on a substrate (conveniently a silicon wafer, but any other substrate can be used) with a spot size that almost corresponds to the needle aperture. Then, when the substrate moves, a pattern is formed accordingly. The writing speed is dependent on the dynamic deposition rate, which can be as high as 2 nm·m·s-1. In the specific case of acetylene used as precursor, the shape of the hydrogenated-carbon spot is strongly dependent on the amount of oxygen-containing impurities present in the microwave argon plasma. The influence of the plasma composition and the local hydrodynamic flow pattern are essential to control the deposition conditions and these aspects will be discussed. In particular, the distance between the needle exit and the substrate turns out to be a key parameter in the deposition process. DISCRIBE offers the advantage of all PECVD processes: it allows deposition at atmospheric pressure and reduced temperature of multi-materials (semiconductors, metals, ceramics, plasma polymers) ony any kind of substrate.
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Stadnyk, Yu V., V. V. Romaka, V. A. Romaka, A. M. Нoryn, L. P. Romaka, V. Ya Krayovskyy, and І. М. Romaniv. "Investigation of Electronic Structure of Zr1-xVxNiSn Semiconductive Solid Solution." Фізика і хімія твердого тіла 20, no. 2 (July 10, 2019): 127–32. http://dx.doi.org/10.15330/pcss.20.2.127-132.
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The peculiarities of electronic and crystal structures of Zr1-xVxNiSn (x = 0 - 0.10) semiconductive solid solution were investigated. To predict Fermi level εF behavior, band gap εg and electrokinetic characteristics of Zr1-xVxNiSn, the distribution of density of electronic states (DOS) was calculated. The mechanism of simultaneous generation of structural defects of donor and acceptor nature was determined based on the results of calculations of electronic structure and measurement of electrical properties of Zr1-xVxNiSn semiconductive solid solution. It was established that in the band gap of Zr1-xVxNiSn the energy states of the impurity donor εD2 and acceptor εA1 levels (donor-acceptor pairs) appear, which determine the mechanisms of conduction of semiconductor.
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Hayashi, S., and K. Yanagihara. "Characterization Of SiO2/Si Interface Using Secondary Ion Mass Spectrometry(Sims) And Laser Post-Ionization Sputtered Neutral Mass Spectrometry(Snms)." Microscopy and Microanalysis 5, S2 (August 1999): 124–25. http://dx.doi.org/10.1017/s1431927600013945.
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SIMS has inherent difficulties with quantification because of the so called “matrix effect”. Many factors contribute to the matrix effect, e.g. differing concentration of oxygen, sputtering rate differences in the hetero-layers, etc. In the case of MOS(metal-oxide-semiconductor) structures, the oxide layer gives rise to a large matrix effect. It is thus very difficult to use SIMS to evaluate the relationship between the electrical properties of the LSI devices and the impurity profiles present in such systems.So we have been studying laser post-ionization SNMS, which consists of TOF-SIMS apparatus and excimer laser, in order to quantify the impurity profiles around SiO2/Si interface. Depth profiles of implanted Cu with 1×1015 atoms/cm2 in SiO2(100 nm)/Si system taken by Monte-Carlo simulation ,SIMS and laser post-ionization SNMS are shown in Fig.l. In this implantation condition the Cu+:Cu2+:Cu3+ percentage ratios of the charge distributions were 44:42:14. Fig. 1(a) shows the theoretical depth profiles expetted from this implantation condition by Monte-Cairo simulation.
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Singh, Andy, Katharina Luening, Sean Brennan, Takayuki Homma, Nobuhiro Kubo, Stanisław H. Nowak, and Piero Pianetta. "Determination of copper nanoparticle size distributions with total reflection X-ray fluorescence spectroscopy." Journal of Synchrotron Radiation 24, no. 1 (January 1, 2017): 283–87. http://dx.doi.org/10.1107/s1600577516015484.
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Total reflection X-ray fluorescence (TXRF) analysis is extensively used by the semiconductor industry for measuring trace metal contamination on silicon surfaces. In addition to determining the quantity of impurities on a surface, TXRF can reveal information about the vertical distribution of contaminants by measuring the fluorescence signal as a function of the angle of incidence. In this study, two samples were intentionally contaminated with copper in non-deoxygenated and deoxygenated ultrapure water (UPW) resulting in impurity profiles that were either atomically dispersed in a thin film or particle-like, respectively. The concentration profile of the samples immersed into deoxygenated UPW was calculated using a theoretical concentration profile representative of particles, yielding a mean particle height of 16.1 nm. However, the resulting theoretical profile suggested that a distribution of particle heights exists on the surface. The fit of the angular distribution data was further refined by minimizing the residual error of a least-squares fit employing a model with a Gaussian distribution of particle heights about the mean height. The presence of a height distribution was also confirmed with atomic force microscopy measurements.
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Chepurnov, V. I. "ASSOCIATES OF DOT DEFECTS OF VARIOUS NATURE IN SiC-PHASE OF SEMICONDUCTOR HETEROSTRUCTURE OF SiC//Si, RECEIVEDBY ENDOTAKSIYA METHOD." Vestnik of Samara University. Natural Science Series 20, no. 7 (May 30, 2017): 145–62. http://dx.doi.org/10.18287/2541-7525-2014-20-7-145-162.
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One of the main ways of increasing of reliability of sensors of physical quantities on the basis of high-temperature and radiation-hardened heterostructure of β-SiC/Si is the analysis of technological aspects of its forming (endotaksiya) regarding concentration distribution of dot defects of various nature, their probable models of association with participation of foreign impurity. Besides, the analysis of reversible processes of association opens ways of optimization of kinetics of diffusive mass transfer at phase transformation of substrate of silicon into a film of carbide of silicon. In the article dependences of concentration of neutral defects on factors of supersaturation of gas phase on conditional atomic concentration of carbon, from concentration of foreign impurity are given in a gas phase, from concentration of own defects of various nature having potential of formation of deep levels in the forbidden zone and potential of association. The analysis of the given dependences is made and recommendations about carrying out technological process of formation of difficult heterostructures of different function are made.
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VELICHKO, O. I. "SIMULATION OF BORON DIFFUSION IN THE NEAR-SURFACE REGION OF SILICON SUBSTRATE." Surface Review and Letters 27, no. 11 (August 18, 2020): 2050010. http://dx.doi.org/10.1142/s0218625x20500109.
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The mechanism of boron-enhanced diffusion from a thin boron layer deposited on the surface in the case of silicon crystal doping is proposed and investigated. It was supposed that lattice contraction occurs in the vicinity of the surface due to the difference between the atomic radii of boron and silicon. This lattice contraction provides a stress-mediated diffusion of silicon self-interstitials from the near-surface region to the bulk of a semiconductor. Due to the stress-mediated diffusion, the near-surface region is depleted of silicon self-interstitials, and simultaneous oversaturation of this species occurs in the bulk. In this way, a strong nonuniform distribution of silicon self-interstitials in the vicinity of the surface is formed without regard to the large migration length of this species. The oversaturation of the bulk of a semiconductor with nonequilibrium self-interstitials allows one to explain the boron-enhanced diffusion of impurity atoms. The strong nonuniform distribution of these point defects also results in a specific form of boron concentration profile in the vicinity of the surface. Good agreement of the calculated boron profile with the experimental data for the entire doped region was obtained within the limit of the proposed model.
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Garcia, L. F., I. D. Mikhailov, and J. Sierra-Ortega. "Magnetoelectric Effect in Type-II Quantum Cone Induced by Donor Impurity." Journal of Nanomaterials 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/4961714.
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We consider a model of donor centered at the base of a type-II nanocone, in which the excessive electron, released from the donor, is located within a narrow tube-shaped shell exterior region around the cone lateral surface. By solving the one-electron Schrödinger equation we analyze the alteration of the spatial probability distribution of the electron, the period of the Aharonov-Bohm oscillations of the energy levels, and the electric and magnetic moments induced by external electric and magnetic fields, applied along the symmetry axis. We show that the diamagnetic confinement provided by the magnetic field forces the electron to climb along the cone’s border, inducing the electric polarization of the structure. Similarly, the external electric field, which pushes the electron toward cone’s bottom, changes the order of the energy levels with different magnetic momenta varying the magnetic polarization of the structure. Our theoretical analysis reveals a new possibility for the coupling between the polarization and magnetization arising from the quantum-size effect in type-II semiconductor nanocones.
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Колпаков, В. А., and С. В. Кричевский. "Особенности механизма диффузии в структуре алюминий-кремний при облучении ее поверхности внеэлектродной плазмой высоковольтного газового разряда." Журнал технической физики 90, no. 1 (2020): 62. http://dx.doi.org/10.21883/jtf.2020.01.48662.212-19.
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Features of the diffusion mechanism in Al-Si structure when its surface is irradiated by off-electrode plasma of high-voltage gas discharge at discharge current I=50 mA, accelerating voltage U=4 kV and radiation durations 90 s < t ≤ 600 s are investigated. Model for calculating the concentration profiles of aluminum impurity distribution in silicon plate as a function of Al-Si structure irradiation parameters is proposed; corresponding analytical dependences and also good consent of the theory and experiment are obtained. It is shown that the maximum values of diffusant concentration are reached at a penetration depth of electrons into the semiconductor because of forming of vacancies by them in a layer (х ≈ 0.25 μm). Specified is followed by increase at 2-3 orders of coefficient of thermal diffusion.
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Blagin, A. V., N. A. Nefedova, and B. M. Seredin. "Physical Aspects of the Liquid Zones Thermomigration Method for Formation of Electronic Technics Materials with the Required Substructure." Materials Science Forum 843 (February 2016): 145–50. http://dx.doi.org/10.4028/www.scientific.net/msf.843.145.
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The paper analyzes the features of a liquid zones thermomigration process in a crystal for the formation of semiconductor materials with the required substructure, carried out in comparison with a diffusion method. The primary factors defining and accompanying the thermomigration process of liquid inclusion in a crystal are considered. The geometrical, concentration, temperature-time and other conditions at which the choice of the thermomigration effect as a local doping method is preferable are revealed and described. It is shown, that the thermomigration method possesses considerable advantages, in particular, the possibilities of decreasing doping process temperature, increasing process speed, increasing the distribution uniformity of the doping impurity and improves the crystal perfection of the doped layers. The quantitative estimations related to the revealed conditions, are illustrated with an aluminium-silicon example.
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Zhao, Fengai, Shuanglin Hu, Canhui Xu, Haiyan Xiao, Xiaosong Zhou, Xiaotao Zu, and Shuming Peng. "Effect of Copper Doping on Electronic Structure and Optical Absorption of Cd33Se33 Quantum Dots." Nanomaterials 11, no. 10 (September 28, 2021): 2531. http://dx.doi.org/10.3390/nano11102531.
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The photophysical properties of Cu-doped CdSe quantum dots (QDs) can be affected by the oxidation state of Cu impurity, but disagreement still exists on the Cu oxidation state (+1 or +2) in these QDs, which is debated and poorly understood for many years. In this work, by using density functional theory (DFT)-based calculations with the Heyd–Scuseria–Ernzerhof (HSE) screened hybrid functional, we clearly demonstrate that the incorporation of Cu dopants into the surface of the magic sized Cd33Se33 QD leads to non-magnetic Cu 3d orbitals distribution and Cu+1 oxidation state, while doping Cu atoms in the core region of QDs can lead to both Cu+1 and Cu+2 oxidation states, depending on the local environment of Cu atoms in the QDs. In addition, it is found that the optical absorption of the Cu-doped Cd33Se33 QD in the visible region is mainly affected by Cu concentration, while the absorption in the infrared regime is closely related to the oxidation state of Cu. The present results enable us to use the doping of Cu impurity in CdSe QDs to achieve special photophysical properties for their applications in high-efficiency photovoltaic devices. The methods used here to resolve the electronic and optical properties of Cu-doped CdSe QDs can be extended to other II-VI semiconductor QDs incorporating transition-metal ions with variable valence.
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Choi, Ji-Ho, Woo-Guk Lee, Tae-Hun Shim, and Jea-Gun Park. "Fumed Silica-Based Ultra-High-Purity Synthetic Quartz Powder via Sol–Gel Process for Advanced Semiconductor Process beyond Design Rule of 3 nm." Nanomaterials 13, no. 3 (January 18, 2023): 390. http://dx.doi.org/10.3390/nano13030390.
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Fumed silica-based ultra-high-purity synthetic quartz powder was developed via the sol–gel process to apply to quartz wares and quartz crucibles for use in advanced semiconductor processes. The process conditions of preparing potassium silicate solution, gelation, and cleaning were optimized, i.e., the relative ratio of fumed silica (10 wt%) to KOH (4 wt%) for potassium silicate solution, gelation time 3 h, and cleaning for 1 h with 5 wt% HCl solution. It was observed that the gelation time strongly affected the size distribution of the quartz powder; i.e., a longer gelation time led to a larger size (d50) of the synthesized quartz powder: 157 μm for 2 h and 331 μm for 5 h. In particular, it was found that the morphology of the as-synthesized quartz powder greatly depended on the pulverizing process; i.e., the shape of quartz powder was shown to be rod-shaped for the without-gel-pulverizing process and granular-shaped with the process. We expect that the fumed silica-based ultra-high-purity quartz powder with an impurity level of 74.1 ppb synthesized via the sol–gel process is applicable as a raw material for quartz wares and crucibles for advanced semiconductor processes beyond the design rule of 3 nm.
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Virag, A., G. Friedbacher, M. Grasserbauer, H. M. Ortner, and P. Wilhartitz. "Multielement ultratrace analysis of molybdenum with high performance secondary ion mass spectrometry." Journal of Materials Research 3, no. 4 (August 1988): 694–704. http://dx.doi.org/10.1557/jmr.1988.0694.
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Electron beam melting has been used to obtain ultrapure refractory metals that are gaining importance in metal oxide semiconductor-very large scale integration (MOS-VLSI) processing technology, fusion reactor technology, or as superconducting materials. Although the technology of electron beam melting is well established in the field of production of very clean refractory metals, little is known about the limitations of the method because the impurity level of the final products is frequently below the detection power of common methods for trace analysis. Characterization of these materials can be accomplished primarily by in situ methods like neutron activation analysis and mass spectrometric methods [glow discharge mass spectrometry (GDMS), secondary ion mass spectrometry (SIMS)]. A suitable method for quantitative multielement ultratrace bulk analysis of molybdenum with SIMS has been developed. Detection limits of the analyzed elements from 10−7g/gdown to 10−12g/g have been found. Additional information about the distribution of the trace elements has been accumulated.
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Kakibayashi, Hiroshi, Kuniyasu Nakamura, and Ruriko Tsuneta. "3-D Observation of Cu Particles Precipitated in Si by High-Angle Hollow-Cone Dark-Field Transmission Electron Microscopy." Microscopy and Microanalysis 3, S2 (August 1997): 479–80. http://dx.doi.org/10.1017/s1431927600009284.
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The performance of electronic devices, such as dynamic random access memories, is degraded by contamination due to impurity atoms as well as crystalline imperfections created during processing. The evaluation of those degradation causes is generally done using an analytical transmission electron microscope. The information obtained, however, is limited to two-dimensional images of the specimen as seen from a single direction. Advanced semiconductor devices with finer-pattern structures are expected to exhibit larger fluctuations in device performance due to the spatial distribution of the faults. A new method has thus been examined to determine the atomic species and to reconstruct three-dimensional (3-D) images of the specimen structure by using high-angle hollow-cone dark-field transmission electron microscopy (HADF-TEM).A incident angle controller was added to a conventional TEM to control the electron-beam deflection coils. This enables the incident electron beam to be inclined and rotated, providing hollow-cone illumination of the specimen, as shown in Fig. 1.
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Chen, Lei, Yu Wang, Yuesong Jia, Xianjun Yang, Chunzhi Li, Lin Yi, Wei Jiang, and Ya Zhang. "Effect of Viscosity on Stopping Power for a Charged Particle Moving above Two-Dimensional Electron Gas." Laser and Particle Beams 2022 (April 29, 2022): 1–12. http://dx.doi.org/10.1155/2022/6903026.
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In two-dimensional (2D) electron systems, the viscous flow is dominant when electron-electron collisions occur more frequently than the impurity or phonon scattering. In this work, a quantum hydrodynamic model, considering viscosity, is proposed to investigate the interaction of a charged particle moving above the two-dimensional viscous electron gas. The stopping power, perturbed electron gas density, and the spatial distribution of the velocity vector field have been theoretically analyzed and numerically calculated. The calculation results show that viscosity affects the spatial distribution and amplitude of the velocity field. The stopping power, which is an essential quantity for describing the interactions of ions with the 2D electron gas, is calculated, indicating that the incident particle will suffer less energy loss due to the weakening of the dynamic electron polarization and induced electric field in 2D electron gas with the viscosity. The values of the stopping power may be more accurate after considering the effect of viscosity. Our results may open up new possibilities to control the interaction of ions with 2D electron gas in the surface of metal or semiconductor heterostructure by variation of the viscosity.
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Zhou, Shixiong, Tingting Shi, Zhihong Chen, Dmitri Kilin, Lingling Shui, Mingliang Jin, Zichuan Yi, et al. "First-Principles Study of Optoelectronic Properties of the Noble Metal (Ag and Pd) Doped BiOX (X = F, Cl, Br, and I) Photocatalytic System." Catalysts 9, no. 2 (February 21, 2019): 198. http://dx.doi.org/10.3390/catal9020198.
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To explore the photocatalytic performances and optoelectronic properties of pure and doped bismuth oxyhalides D-doped BiOX (D = Ag, Pd; X = F, Cl, Br, I) compounds, their atomic properties, electronic structures, and optical properties were systematically investigated using first-principles calculations. In previous experiments, the BiOX (X = Cl, Br) based system has been observed with enhanced visible light photocatalytic activity driven by the Ag dopant. Our calculations also show that the potential photocatalytic performance of Ag-doped BiOCl or BiOBr systems is enhanced greatly under visible light, compared with other Pd-doped BiOX (X = Cl, Br) compounds. Furthermore, it is intriguing to find that the Pd-doped BiOF compound has strong absorption over the infrared and visible light spectrum, which may offer an effective strategy for a promising full spectrum catalyst. Indicated by various Mulliken charge distributions and different impurity states in the gap when Ag or Pd was doped in the BiOX compounds, we notice that all D-doped BiOXs exhibit a p-type semiconductor, and all impurity levels originated from the D-4d state. The charge transfer, optoelectronic properties, and absorption coefficients for photocatalytic activities among D-doped BiOX photocatalysts caused by the electronegativity difference of halide elements and metal atoms will finally affect the photocatalytic activity of doped BiOX systems. Therefore, it is significant to understand the inside physical mechanism of the enhanced Ag/Pd-doped BiOX photocatalysts through density functional theory.
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SRINIVAS, K., and P. VENUGOPAL REDDY. "THE INFLUENCE OF NANOMETRIC SIZE ON VARIOUS PROPERTIES OF NANOCRYSTALLINE Zn0.9Ni0.1O DILUTED MAGNETIC SEMICONDUCTORS." International Journal of Nanoscience 10, no. 04n05 (August 2011): 949–54. http://dx.doi.org/10.1142/s0219581x11008733.
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With a view to understand the influence of nanometric size on various properties of nanocrystalline Zn0.9Ni0.1O diluted magnetic semiconductors, a systematic investigation has been undertaken. Samples were prepared for the first time by hydrazine assisted polyol method and are post annealed in air at different temperatures to vary the crystallite size. From the Rietveld refinement of XRD data, the isotropic crystallite size values are found to be in the range, 15–42 nm. Further, the phase analysis of Rietveld refined XRD data, FT-IR and optical absorbance spectral studies revealed that all the samples are having hexagonal wurzite structure without any detectable impurity phases. From AFM topography studies, it has been found that the surface condition of the grains and their distributions clearly depend on the nano size of the materials. From the PL measurements, the local defects of the materials were explored. From magnetization studies which were carried out by using VSM and MFM techniques, it has been found that all the samples are found to exhibit a clear ferromagnetic hysteresis behavior at room temperature without any magnetic clusters. Finally, electrical properties were also undertaken at room temperature to understand the variation of magnetic behavior as a function of nanometric size of these materials.
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Papin, A. A., and A. P. Mazhirin. "Example of an exact solution of the problem of the distribution of an ionized impurity in the surface region of a semiconductor." Journal of Applied Mechanics and Technical Physics 39, no. 4 (July 1998): 493–500. http://dx.doi.org/10.1007/bf02471241.
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Gavrilovets, V. V., V. B. Bondarenko, Yu A. Kudinov, and V. V. Korablev. "Equilibrium distributions of shallow-level impurity and potential in the near-surface region of a semiconductor in a model with a completely depleted layer." Semiconductors 34, no. 4 (April 2000): 441–44. http://dx.doi.org/10.1134/1.1188004.
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Kupchak, I. M., D. V. Korbutyak, and N. F. Serpak. "Electronic characteristics of CdS quantum dots with defects." Технология и конструирование в электронной аппаратуре, no. 3-4 (2020): 28. http://dx.doi.org/10.15222/tkea2020.3-4.28.
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Using the density functional theory and the generalized gradient approximation, we calculated the atomic structure, the density of electronic states, and the optical absorption spectra of CdS quantum dots containing intrinsic defects — a cadmium vacancy VCd and an interstitial sulfur atom SI, and substitutional impurities — zinc and copper in place of the atom cadmium — ZnCd and CuCd, respectively. The calculations were performed for the Cd33S33 cluster corresponding to the so-called “magic” size of the quantum dot. This size has a minimum of dangling bonds at the surface and allows the using of such a cluster without the passivation. The structural relaxation during the formation of such defects and the distribution of the wave function of the state corresponding to the top of the valence band are analyzed in details. It has been shown that the cadmium vacancy forms local states in the band gap of CdS nanocrystals, and can serve as centers of radiative recombination. Other defects form energy levels in the depths of the valence band or near its top, but whose energy positions do not correspond to the band maxima in the experimental photoluminescence spectra of CdS quantum dots, both undoped and doped with zinc. The calculated optical absorption spectra demonstrate a strong peak in the region of fundamental absorption of CdS for a cluster containing a substitutional impurity of CuCd, in contrast to other systems where no such peaks are observed. In addition, the replacement of the cadmium atom with copper leads to a decrease in the number of chemical bonds to three and, accordingly, to the largest relaxation among the systems studied. This feature is caused by the crystal structure inhomogeneity of copper sulfide CuxS, which, depending on stoichiometry, can be either a semiconductor or a metal.
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Krayovskyy, Volodymyr, Volodymyr Pashkevych, Andriy Horpenuk, Volodymyr Romaka, Yuriy Stadnyk, Lyubov Romaka, Andriy Horyn, and Vitaliy Romaka. "RESEARCH OF THERMOMETRIC MATERIAL Er1-xScxNiSb. I. MODELLING OF PERFORMANCES." Measuring Equipment and Metrology 82, no. 2 (2021): 16–21. http://dx.doi.org/10.23939/istcmtm2021.02.016.
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Automated The results of modeling performances of the semiconductor solid solution Er1-xScxNiSb are presented, which can be a promising thermometric material for the manufacture of sensitive elements of thermoelectric and electroresistive thermocouples. Fullprof Suite software was used to model the crystallographic characteristics of the Er1-xScxNiSb thermometric material. Modeling of the electronic structure of Er1-xScxNiSb was performed by Coring-Kon-Rostocker methods in the approximation of coherent potential and local density using the exchange-correlation potential Moruzzi-Janak-Williams and Linear Muffin-Tin Orbital in the framework of DFT density functional theory. The Brillouin zone was divided into 1000 k-points, which were used to model energetic performances by calculating DOS. The width of the energy window was 22 eV and was chosen to capture all semi-core states of p-elements. Full potential (FP) was used in the representation of the linear MT orbital in the representation of plane waves. The accuracy of calculating the position of the Fermi level was εF ± 6 meV. To verify the existence of a continuous solid solution, Er1-xScxNiSb substitution, the change in the values of the period of the unit cell a (x) was calculated within the framework of the DFT density functional theory in the range x = 0–1.0. It is presented that the calculated and experimentally obtained dependences of the period of the unit cell a(x) Er1-xScxNiSb are almost parallel, which confirms the correctness of the used tools and the obtained modeling results. To research the possibility of obtaining thermometric material Er1-xScxNiSb in the form of a continuous solid solution was performed modeling of thermodynamic calculations in the approximation of harmonic oscillations of atoms in the theory of DFT density functional for a hypothetical solid solution Er1-xScxNiSb, x = 0–1.0. It is shown that the change in the values of free energy ΔG(x) (Helmholtz potential) passes through the minimum at the concentration x≈0.1 for all temperatures of possible homogenizing annealing of the samples, indicating the solubility limit of Sc atoms in the structure of the ErNiSb compound. The presence of this minimum indicates that the substitution of Er atoms for Sc atoms in the ErNiSb compound is energetically advantageous only up to the concentration of impurity atoms Sc, x≈0.1. At higher concentrations of Sc atoms, x> 0.10, stratification occurs (spinoidal phase decay). It is shown that modeling of the mixing entropy behavior S even at a hypothetical temperature T = 4000 K shows the absence of complete solubility of Sc atoms in Er1-xScxNiSb. To model the energetic and kinetic performances of the semiconductor thermometric material Er1-xScxNiSb, particularly the behavior of the Fermi level F e , bandgap width g e the distribution of the density of electronic states (DOS) and the behavior of its electrical resistance ρ(x, T) is calculated for an ordered variant of the structure in which the Er atoms in position 4a are replaced by Sc atoms. It is shown that the ErNiSb compound is a semiconductor of the electronic conductivity type, in which the Fermi level is located near the level of the conduction band C e . The modeling showed that at higher concentrations of Sc atoms, the number of generated acceptors exceeds the concentration of uncontrolled donors, and the concentration of free holes exceeds the concentration of electrons. Under these conditions, the Fermi level F e approaches, and then the level of the valence band Er1- xScxNiSb crosses: the dielectric-metal conductivity transition occurs. The experiment should change the sign of the thermo-emf coefficient α(x, T) Er1-xScxNiSb from negative to positive, and the intersection of the Fermi level F e and the valence band changes the conductivity from activating to metallic: on the dependences ln(ρ(1/T)) the activation sites disappear, and the values of resistivity ρ increase with temperature.