Abstract The value of exchange energy for near-surface double-donor and double-quantum dot structures under the effect of external electric field has been calculated using unrestricted Hartree–Fock method. The dependences of exchange energy on geometric parameters have been obtained. It has been found that the location of donor centers near the surface of the semiconductor leads to an increase in the

Abstract The electron spectrum in a uniform nanowire with a hexagonal cross-section is calculated by means of a numerical diagonalization of the effective-mass Hamiltonian. Two basis sets are utilized. The wave-functions of low-lying states are calculated and visualized. The approach has an advantage over mesh methods based on finite-differences (or finite-elements) schemes: non-physical solutions

Abstract In this work, we applied automatic design generation techniques to obtain the most efficient quantum cascade laser (QCL) structures for the mid-infrared range. For simulations, the transfer matrix, ensemble Monte Carlo and density matrix techniques, accelerated with CUDA computation technology, were utilized. As a result, several designs were created using the modification of the genetic algorithm

Abstract It is shown theoretically, that the phenomenon of radiation focusing in a small region of the near zone inside a dielectric film can present due to electromagnetic wave transmission through sub-wavelength nanoapertures. The confirmation is based on the rigorous theory of plane wave diffraction by a slot in a perfectly conducting screen of finite thickness in the presence of a plane dielectric

Abstract During the self-catalyzed GaAs nanowire growth formation of parasitic GaAs crystallites is observed. The reasons for crystallite formation are explained on the base of Monte Carlo simulation results. During simultaneous deposition of gallium and arsenic on the GaAs(111)B substrate coated by a silicon oxide film, liquid gallium droplets nucleate on the oxide surface. After nucleation, droplets

Abstract Investigation of GaN epitaxial layers on silicon substrates is driven by high potential for fabrication of high efficiency and relatively low-cost electronic devises. Growth process of GaN layers on Si by molecular-beam epitaxy is complicated by mutual diffusion of Si and Ga and differences in thermal expansion coefficients and lattice parameters causing large number of defects. To improve

Abstract In this work, a versatile method to increase the optical response of oxide nanostructures is described. Thin TiO2 films with buried gold nanoparticles (TiO2-AuNP) were synthesized on a crystalline Si surface. The localized surface plasmon resonance reflection maximum is formed around 720–750 nm. Current-voltage characteristics of planar structures formed by use of different contact materials

Abstract The Ag/Ge/Si(001) stacks with threading dislocations growing through the Ge epitaxial layers (ELs) manifested bipolar resistive switching (RS) between two metastable resistance states. Scanning transmission electron microscopy (STEM) provided a direct evidenced the RS mechanism to consist in the electrodiffusion of Ag+ ions along the dislocations in the Ge ELs. Also, STEM revealed multiple

Abstract Passivation of the n-InP(100) surface with sodium sulfide (Na2S) aqueous solution is analyzed by photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). The room-temperature PL intensity increases essentially even after short treatment with sulfide solution for 1 min. The enhancement in the room-temperature PL intensity after passivation decreases with the increase in the bulk doping

Abstract The structural and magnetic properties of FeCo–C films produced by electroless plating with different carbohydrates as reducing agents have been investigated. The surface morphology and coercivities of FeCo–C films are dependent on the iron content and type of reducing agent. The local magnetic anisotropy field value increases with a decrease in Fe content. For all systems, deposits with good

Abstract The feature of the promising tool of lithographic nanostructuring based on selective exposure of polymer resist by ion beam is very compact (of about tens of nanometers) beam interaction volume. Herewith the main part of beam energy is deposited in the resist and is spent to its modification. It causes the set of advantages specific for this method: sub-10 nanometer resolution achievable,

Abstract—The influence of the supply voltage and temperature on the characteristics of the photoresponse of silicon photoelectric multipliers has not been adequately studied. In this study, the influence of these factors on the time characteristics of the photoresponse of silicon photoelectric multipliers is investigated. A block diagram of the experimental system is presented. In the system, the optical

Abstract One of the most promising platforms to implement quantum technologies are coupled electron-nuclear spins in diamond in which the electrons of paramagnetic color centers play a role of “fast” qubits, while nuclear spins of nearby 13C atoms can store quantum information for a very long time due to their exceptionally high isolation from the environment. Essential prerequisite for a high-fidelity

Abstract In this paper, we investigate the features of reflection of a plane elliptically polarized electromagnetic wave fallen from isotropic transparent dielectric on a layer of hyperbolic metamaterial with optical axis in an interface and main effective dielectric permittivities less than the permittivity of dielectric. The cases are analyzed when one (ordinary or extraordinary) wave or two waves

Abstract Using the semi-empirical quantum chemical PM3 method the energies of carbon nanoscrolls formed from flat zigzag graphene nanoribbons 46zGNR and 70zGNR are calculated. For this purpose a simple algorithm to define the Cartesian coordinates of the atoms of a carbon nanoscroll is proposed. The dependences of the energy of the nanoscrolls relative to the energy of the corresponding flat nanoribbon

Abstract We predict the characteristics of hyperfine interactions (hfi) for a number of electron-nuclear spin systems NV-13C in diamonds grown by seeding approach from the specific isotopic aza-adamantane or methyl-aza-adamantane molecules differing in 13C position in the precursor as well as in the orientation of the NV center in the post-obtained diamond. For the purpose we have used the spatial

Abstract A new approach for calculating the ion dose spatial distribution of the focused ion beam is proposed. The approach is based on the analysis of the secondary electron microscopy image of the area irradiated by the focused ion beam.

Abstract Magnetostatic surface waves (MSSW) propagation and electromotive force (EMF) generation effects in 14.6 µm-thick yttrium iron garnet (YIG) film covered by 8 nm-thick Pt layer was studied. It was found that MSSW dispersion k = k(f) and transmission S21(f) characteristics in the YIG/Pt structure are very similar to that of the free YIG film. For YIG/Pt structure, we show that EMF (U) demonstrates

Abstract Electronic structure of molybdenum oxides obtained by the oxidation of molybdenum at an oxygen pressure of 1 Torr (thin film) and air (thick film) was studied. It was shown that a thick oxide film is formed from MoO3 oxide, and a thin film from a mixture of MoO3 and MoO2 oxides, which is reflected in the form of valence band spectra. Oxygen on the surface belongs both in molybdenum oxide and

Abstract The structural and some other characteristics of quasi-freestanding single-layer graphene obtained by annealing of the buffer layer in the flow of hydrogen are studied in comparison with those of conventional epitaxial graphene. The high structural quality and good lateral uniformity of the thus-obtained graphene film are checked and confirmed by the use of such techniques as Raman spectroscopy

Abstract Ferromagnetic resonance was used to study three types of ferrihydrite nanoparticles: nanoparticles formed as a result of the cultivation of microorganisms Klebsiella oxytoca; chemically prepared ferrihydrite nanoparticles; chemically prepared ferrihydrite nanoparticles doped with Cu. It is established from the ferromagnetic resonance data that the frequency-field dependence (in the temperature

Abstract The “germanium-vacancy” (GeV) center in diamond can be used as Temperature Sensors. The idea of GeV-based thermometry is based on optical measurements of the spectral shift of the zero-phonon line and its spectral width as a function of temperature changes. At the same time optical characteristics of GeV center which is located near-surface could be modified by formation of defect states in

Abstract Polymer nanocomposites based on Cu(Cu2O)-LDPE with a volume fraction of 0.1–0.4 copper filler in the form of spherical nanoparticles with sizes from 10 to 25 nm were synthesized. The electrical conductivity of such composite nanomaterials was measured, which is 4.5–5 times higher than the electrical conductivity of a polyethylene matrix. To predict the electrical conductivity of such materials

Abstract We report the results of systematic experimental and theoretical studies of structural and dynamical properties of short-period GaN/AlN superlattices. The multilayer structures with the thicknesses of the constituent layers varying from two to several monolayers are grown using the submonolayer digital molecular beam epitaxy technique. In the framework of density functional theory, the lattice

Abstract Forward and reverse current–voltage characteristics of commercial rectifier diodes based on a Schottky barrier to 4H-SiC are studied in the temperature range 20–370°C at a maximum current of 10–20 mA and maximum voltage of 10–100V. It is found that the diodes can be considered nearly ideal with a Schottky-barrier height of ~1.5 eV, with the forward current over the entire temperature range

Abstract The magnetic moment of the unmodulated bilayer graphene is calculated in the presence of a perpendicular magnetic field B. The oscillatory character of the magnetic moment dependences on the magnetic field is investigated.

Abstract Recently Ma et al. (Nature Nanotech. 14, 145, 2019) reported an intrinsic photocurrent in graphene, which occurs as the authors believe “in a different parameter regime from all the previously observed photothermoelectric or photovoltaic photocurrents in graphene”. Here we present an alternative – obvious and transparent explanation of such experiments. We demonstrate that the photo effect

Abstract Raman spectroscopy is used to evaluate the structural perfection of epitaxial graphene films before and after deposition of a Ni layer to their surface by magnetron sputtering. Two deposition modes with different gas pressures and deposition times are investigated. It is found that Ni deposition under low pressure combined with long deposition time does not lead to the separation of graphene/Ni

Abstract A MoS2 sheet in its 1T ' phase is a two-dimensional topological insulator. It possesses highly conductive edge states which, due to topological protection, are insensitive to back scattering and are suitable for device channels. A transition between the topological and conventional insulator phases in a wide 1T '-MoS2 sheet is controlled by an electric field orthogonal to the sheet. In order

Abstract We consider the construction of exactly solvable models of twisted carbon nanotubes by applying Darboux transformation to the square of the Dirac-like Hamiltonian, describing the low-energy dynamics of charge carriers. It is shown that obtained two pseudo-Schrodinger expressions are intertwined, demonstrating supersymmetry structure. It is proved, that for the considered class of pseudo-scalar

Abstract We found bulk n-GaAs layers grown by liquid phase epitaxy to be irregularly stressed. Deformation created by this stress causes a small but detectable quadrupole splitting of Zeeman nuclear energy levels. In our work we detected a very weak quadrupole splitting for 69Ga and 75As isotopes in bulk n-GaAs and obtained the value of the sample deformation. To this end, we used a new method that

Abstract Applying the conventional Floquet theory of periodically driven quantum systems, we developed the theory of optical control of structures based on gapless semiconductors. It is demonstrated that electronic properties of the structures crucially depends on irradiation. Particularly, irradiation by a circularly polarized electromagnetic wave lifts spin degeneracy of electronic bands and induces

Abstact —We study spin-valley relaxation dynamics in two-dimensional MoxW1–xSe2/WSe2 heterobilayers with different relative Mo/W concentration x in the monolayer alloy. Three types of heterobilayers with x = 1.00, 0.50, 0.33 are studied in time-resolved Kerr rotation experiments for different wavelengths and temperatures. The spin-valley relaxation times are found to decrease from ~10 nanoseconds for

Abstract Theory of plasmon-exciton coupling is developed for a metal nanocylinder grating located in the vicinity of a semiconductor quantum well. In dipole approximation, the effective polarizability of cylinders is derived, taking into account generation of quantum-well excitons in the near field of surface plasmons. Given the polarizability, the spectra of reflection and absorption are calculated

Abstract Films of the composition Ba0.8Sr0.2TiO3 (BST 80/20) are synthesized on a silicon substrate by the method of the high-frequency sputtering of a polycrystalline target. The results of investigations of the film composition, the electrophysical properties of capacitor structures based on them, and the dependence of these properties on the material (Al, Cu, Ni, Cr) of the upper electrode are presented

Abstract In this work, drain current ID for 7-nm gate length dual-material (DM) cylindrical gate all around (CGAA) silicon nanowire (SiNW) has been studied and simulation results are reported using Silvaco ATLAS 3D TCAD. In this device, we consider the non-equilibrium Green’s function (NEGF) approach and self-consistent solution of Schrödinger's equation with Poisson’s equation. The splitting of conduction

Abstract The technology of producing a Ge–GeS:Nd heterojunction and the relative spectral characteristics of the quantum efficiency of the fabricated heterojunction are investigated at different γ-irradiation doses. It is found that the photosensitivity increases at a dose of 30 krad in the spectral range of 0.4–2.0 μm. With increasing the radiation dose to 100 krad, the heterojunction photosensitivity

Abstract We have studied experimentally a series of samples of layered MoS2 flakes with thicknesses varying from 1 to 10 μm and observed their strong in-plane optical anisotropy, which we attribute to the effects of strain in combination with fluctuations in the direction of the C-axis. This optical anisotropy allows us to convert the polarization of transmitted light from linear to circular with the

Abstract The results of a study into the effect of irradiation with heavy Ar ions on the structural and optical characteristics of 4H-SiC are presented. It is shown that even upon single-time irradiation with 53-MeV Ar ions at a fluence of 1 × 1010 cm–2 there are at least two powerful local regions with negative deformation dominant in the structure of silicon carbide. Also, a region with positive

Abstract Observation of the resonance enhancement of the intensity of light scattering by optical phonons in a diamond crystal with nitogen-vacancy centres is reported. It is established that the unusual resonance with electronic transitions for optically active nitrogen impurities with both zero-phonon-lines plays the determining role in the increase in intensity of such scattering: at 575.468 nm

Abstract The Bose–Einstein condensation of the two-dimensional magnetoexciton gas with Dirac cone dispersion law is possible at different from zero critical temperature. The partition function, the thermodynamic function such as the free and full energies, entropy and heat capacity were calculated in both gaseous and degenerate phases. The second order phase transition takes place. The jump of the

Abstract The energy spectrum of the exciton and carrier states in a shallow GaAs/AlGaAs quantum well is experimentally studied by means of the spectroscopy of the nonradiative broadening of exciton resonances and the spectroscopy of the photoluminescence excitation. The observed peculiarities of the spectra are treated using the numerical solution of the one-dimensional Schrödinger equation for free

Abstract In this work, we study the exchange interactions between two excitons in the GaAs/AlGaAs quantum wells of various widths. We numerically solved the Schrödinger equation for an exciton in a quantum well to find the two-exciton wave functions and to calculate the exchange integral. The results suggest that the strongest interactions between excitons occur in the quantum wells of widths of about

Abstract In this work, we have prepared the undoped and Al-doped ZnO thin films by a homemade spray pyrolysis method at 450°C onto glass substrates. The X-ray diffraction patterns of undoped ZnO and aluminized zinc-oxide (AZO) thin films exhibit hexagonal wurtzite crystal structure with high crystalline quality, the crystallite size is nanometric. The morphology of the undoped and Al-doped ZnO thin

Abstract The degree of disordering and the thickness d of disordered layers and their effect on the band gap Eg of single-crystal Si(111) under Ar+-ion bombardment are studied for the first time. It is shown that the d value at ion energies of E0 = 1 and 2 keV is ~(100–120) and ~(150–160) Å, respectively. In this case, the density of states of electrons in the Si(111) valence band significantly changes

Abstract The linear-circular dichroism of two- and three-photon absorption in p-type cubic-symmetry semiconductors is theoretically studied. The matrix elements of two- and three-photon optical transitions between subbands of the semiconductor valence band are calculated. In this case, transitions associated with both the non-simultaneous absorption of individual photons and the simultaneous absorption

Abstract In the present study, undoped and Mn-doped ZnS, Zn1 – xMnxS (x = 0, 0.02, 0.06, 0.10) quantum dots (QDs) were successfully synthesized using the simple co-precipitation method. The synthesized samples were thoroughly studied using X-ray diffraction (XRD), UV-visible absorption, high-resolution transmission electron microscopy (HRTEM) with selected area of the electron diffraction, scanning

Abstract In the UV-visible-near infrared regions from 245 to 1000 nm, variable-angle spectroscopic ellipsometer (VASE) was used to investigate optical functions of As2S3 and As2Se3 thin films. In the entire measured spectral range, data were analyzed by assembly from several dispersion models. These assemblies comprise individual Tauc–Lorentz supplemented by several Lorentz (TL-group) or single Cody–Lorentz

Abstract In the context of Haldane–Anderson’s model, the transferred charge and the energy of adsorption of alkali metal and halogen atoms on the C and Si faces of the 3C-, 6H-, and 4H-SiC polytypes are estimated. The contributions of the band and local states to the formation of the charge of adatoms and the metallic and ionic components of the adsorption energy are clarified.

Abstract The specific features are presented of the two-stage synthesis of structured microsystems based on zinc-oxide nanorods by ultrasonic spray pyrolysis and the low-temperature hydrothermal method, with nucleation suppressed in the bulk of the solution. It is shown that the use of two-stage synthesis provides control over the size and aspect ratio of separate nanorods and over the structure of

Abstract The conditions of the laser-stimulated synthesis reaction of silicon-carbide nanoparticles are determined and their characterization is performed. The laser synthesis reaction of SiC particles in the gas phase is observed with the SiH4/C2H2 flow ratio in the range of 1.6–3.2. The temperature in the reaction-zone region is ~1400–1500°C. Silicon-carbide nanoparticles ~6 nm in diameter are fabricated

Abstract Physics-based two-dimensional numerical simulations are performed to analyze the device characteristics of tri-isopropylsilylethynyl (TIPS)-pentacene organic thin-film transistor (OTFT) fabricated using drop-casting technique. Further, using simulation technique enabling calibration this paper also presents the systematic study of the impact of active layer (TIPS-pentacene) thickness on device

The main morphological parameters of 50-ohm Au/ i -GaAs{100} thin-film microwave microstrip gold coplanar transmission lines of the length l W affecting the active resistance of their skin layer R and inductance L are determined. It is found that the lateral character of the grain distribution and developed relief of their surfaces causes the appearance of additional electron scattering both at grain

The bulk (crystal-chemical and structural) and surface (acid base) properties of InBV–ZnS semiconductor solid solutions with different AIII–BV (InP and InAs) binary components are investigated under identical conditions. The regularities of the variation in the investigated properties with composition, which are generally statistical (smooth) for the InP–ZnS system and have extrema for the InAs–ZnS

The results of studies of the surface morphology, electrical characteristics, and photoluminescence properties of epitaxial GaAs films grown by molecular-beam epitaxy on GaAs(110) substrates and doped with Si are reported. A series of samples is grown at a temperature of 580°C with the arsenic/gallium flow ratio in the range from 14 to 80. By analyzing the photoluminescence spectra of the samples,

This work deals with estimation of the Schottky diode (Au|GaN|GaAs) optimal parameters. For this purpose, advanced swarm intelligence (SI) algorithms have been applied, i.e., Harris hawks optimization, ant lion optimizer (ALO), grey wolf optimizer, and whale optimization algorithm. The performance of the SI algorithms has been investigated by a comparative study following the analytical methods developed

Electrical measurements on heavily doped n -type germanium subjected to gamma-irradiation show that the features of impurity-related defect formation before n – p conversion of conductivity type are the same as those previously observed in lightly and moderately doped materials, thus extending the range of doping from ≈1014 to ≈1016 cm–3. It is clear now that the presently adopted model of the dominant

To estimate the physical characteristics of cubic boron arsenide, Keating’s model of force constants and Harrison’s method of bonding orbitals are used. The harmonic and anharmonic characteristics are considered. Comparison of the results with experimental data and other calculations shows the adequate applicability of the approach.

Abstract The relaxation times of the lower p states of the arsenic donor in a germanium crystal strained along the [111] crystallographic direction are studied. Measurements are performed by the pump–probe method, using free-electron laser radiation. The states are excited from the 1s (Γ1) ground state. The experimentally measured decay times of the 2p0, 3p0, and 2p± states are 1.3, no more than 0

Abstract Ge/Si layers are formed on Si/SiO2/Si(100) substrates and are investigated for different growth temperatures. The Si layer is grown by molecular-beam epitaxy, while the Ge layer is produced by the hot wire chemical vapor deposition. Structural studies are carried out using high-resolution transmission electron microscopy and reflection high-energy electron diffraction. Such structures are