Abstract The study concerns the issue of how the morphological characteristics and optical properties of morphologically branched InGaN nanostructures grown on the Si(111) surface by molecular-beam epitaxy depend on the substrate temperature. It is shown that, as the substrate temperature is elevated, the height of InGaN nanocolumns formed at the initial stage of growth increases. In addition, an increase

Abstract It is known that diamond-like carbon layers consist of carbon components with sp2 (graphite) and sp3 (diamond) hybridizations of electron orbitals. The quantitative ratio between sp2 and sp3 components has a profound effect on the structural, morphological, optical, electrical, and mechanical properties of the films. In this study, the possibility of controlling the fractions of sp2- and sp3-hybridized

Abstract The relaxation rates of arsenic donor states in germanium upon interaction with acoustic phonons are analyzed depending on uniaxial crystal compression deformation along [110] direction at low temperatures (<10 K). It is shown that the formation of the inverse population of donor levels, which depends on the crystal-deformation magnitude, occurs under optical excitation, which gives us grounds

Abstract Cu2ZnSnS4 is suitable for high-performance thin-film solar cell because of its high absorbance coefficient, presence of non-toxic elements, excellent optoelectronic properties, and a near-perfect direct band gap. The effect of thermal annealing time (1–4 h) on the optical, morphological, and structural properties of Cu2ZnSnS4 coated through a simple solution processable method has been studied

Abstract The features of the surface shape of GaAs epitaxial layers grown on grooves several micrometers wide with vertical walls and an aspect ratio close to unity are investigated. The grooves are formed on the surface of a GaAs wafer in a plasma-chemical etching installation and overgrown by organometallic vapor-phase epitaxy under reduced pressure in a reactor.

Abstract Data on the synthesis of structures for a quantum cascade terahertz laser in the AlGaAs/GaAs material system on GaAs substrates using the molecular-beam-epitaxy method and their characterization are presented. The specific features necessary for the implementation of such structures are considered. It is shown that, for this configuration, almost single-mode lasing is observed at a frequency

Abstract The fabrication process of ohmic contacts to a diamond-like carbon (DLC) layer is described with the sequential deposition of a Au/Mo/Ti metallic layer onto it. The contacts have good mechanical and adhesion properties. Their specific contact resistance is varied from 1.4 × 10–4 to 6.4 × 10–5 Ω cm2 depending on the DLC layer thickness. The temperature dependence of the layer film resistance

Abstract It is shown for the first time that Co subnanometer coatings deposited by molecular-beam epitaxy on the (0001) surface of the topological insulator BiSbTeSe2 at a temperature of 330°C open an energy gap in the spectrum of topological surface states in the region of the Dirac point with a shift of the Dirac-point position caused by the preliminary deposition of an adsorbate at room temperature

Abstract The photoluminescence spectra of waveguide AlSb/InAs/GaInSb/InAs/AlSb quantum-well heterostructures designed for the generation of radiation at interband transitions in the mid-infrared region have been studied. The experimentally detected spectral lines are correlated with calculations of the band structure.

Abstract The nonlinearity of the gate–drain current–voltage characteristics in classical Schottky transistors and two-dimensional electron gas field-effect transistors based on AlGaAs/InGaAs/GaAs and InGaAs/GaAs compounds is analyzed. The carrier velocity-overshoot effect in the transistor channel is analyzed for various doping profiles of the structures under study.

Abstract The results of experiments aimed at fabricating and studying the properties of photodetector structures based on single-layer graphene produced by chemical vapor deposition are presented. The configuration of a Ta2O5 vertical microcavity with a resonance wavelength of about 850 nm and a lower dielectric SiO2/Ta2O5 distributed Bragg reflector is taken as the base structure. The conditions for

Abstract The photoresponse is investigated in the frequency range of 0.15–15 THz in HgCdTe epitaxial layers with a cadmium concentration from 15.2 to 19.2% grown by molecular-beam epitaxy. It is shown that narrow-gap and gapless HgCdTe solid solutions can be used as detectors of both terahertz and sub-terahertz radiation with a characteristic response time of 2–4 ns and with a sensitivity approaching

Abstract The rate of the multiphonon relaxation of the 1s(T2) level in Se+ donors in silicon is estimated. The calculation comprises the initial approach to the problem, in which the most simplified form of wave functions is used. To evaluate the transition probability, the Pässler expression known from publications is used [R. Pässler, Czech. J. Phys. B 24, 322 (1974)]. This expression was derived

Abstract The change in the carrier mobility in GaAs structures after irradiation is numerically simulated. For each investigated scattering potential, the model parameters are determined at which the calculation data are consistent with the results of the experiment. It is shown for the first time that the form of the potential of scattering at radiation-induced defects determines the time and space

Abstract We interpret the recent observations of Otsuji’s team (Sendai) on switching from absorption to amplification at a temperature of T = 300 K during the passage of terahertz radiation through hexagonal boron nitride–graphene sandwiches with multiple gates on the surface with an increase in the electric field in graphene. It is shown that these effects are related to dispersion and negative conductivity

Abstract Within the coupled wave method complemented by the quasi-optical approach, the feasibility of diffraction-mode selection over the transverse index in lasers with planar Bragg resonators is studied. Acceptable Fresnel parameters at which the diffraction losses from the Bragg-structure edges provide steady-state single-mode lasing with a narrow angular spectrum are determined. It is shown that

Abstract The behavior of phosphorus donors in bulk single-crystal monoisotopic Si1 – xGex alloys (x = 0.0039–0.05) enriched by zero-spin isotopes 28Si (99.998%) and 72Ge (99.984%) by the electron-spin-resonance method is investigated. The hyperfine structure of the donor-electron spectrum giving information on the density of the donor wave function in the ground state on the 31P nucleus (I = 1/2) as

Abstract In the present work, we have fabricated and characterized in the development of methylammonium lead iodide (CH3NH3PbI3) perovskite-based hole transport layer (HTL)-free photodiode with configuration (FTO|CH3NH3PbI3|PC60BM{[6,6]-phenyl-C60-butyric acid methyl ester}|Al. The one-step spin coating technique has been used for the deposition of the precursor solution including methylammonium iodide

Abstract ZnO thin films were formed on c-plane sapphire and p-GaN substrates by pulsed laser deposition (PLD) and radio frequency (RF) magnetron sputtering techniques. XRD analysis including omega scan depicted the formation of highly textured wurtzite ZnO with c-axis. The texture was primarily introduced by the substrate effects as the planes lying at oblique angles also exhibited six-fold symmetry

Abstract The spin-depolarized electron system in a GaAs quantum well at the filling factor ν = 1 is investigated using the time-resolved Kerr rotation technique. At temperatures above 5 K, a transition from the new spin-correlated state to a state with a low spin stiffness characteristic of a single-particle electron system is observed. A nonlinear contribution to the damping of Larmor oscillations

Abstract A study of the processes of the thermal carbonization of silicon monoxide in the presence of nonstoichiometric carbon monofluoride demonstrated that raising the annealing temperature of mixtures of SiO and CFx powders in a quasi-closed volume to 1000°C and higher leads to the formation of whisker-like SiC nanocrystals. It is found that, in parallel with the known crystallization of SiC nanowires

Abstract After the ion implantation of silicon into sapphire followed by high-temperature annealing, silicon and aluminosilicate precipitates are observed in the surface region of sapphire. X-ray measurements with the mapping of reciprocal space show the presence of a compressive stress with a –0.12% strain in the normal direction, and a tensile stress with a 0.2% strain in the R plane in this region

Abstract Processes of Raman scattering of quasi-single-photon pulses in a single-mode optical fiber with pumping are theoretically considered. The peculiarity of the post-pumping scattering is that the pumping creates non-equilibrium molecular vibrations, which significantly increases the probability of Raman scattering in the optical fiber. Non-equilibrium vibrations are expected when the stimulated

Abstract Nanocrystalline phases and GaAlP films are obtained by implanting Al+ ions with E0 = 1 keV at different doses on the surface of a GaP(111) single crystal, and their electronic and crystalline structures are studied. It is shown that the type and the lattice parameters of the three-component nanostructure are in good agreement with those for the substrate. The relationship between the band

Abstract The dependence of the photoconductivity sign on the bias voltage, intensity, and duration of illumination is studied for PbSnTe:In films in the space-charge-limited current regime. The role of traps (including surface ones) with a complex energy spectrum in the effects under observation is discussed.

Abstract The influence of γ radiation on surface defect formation at the Si–SiO2 interface in a p-type-channel metal—oxide-silicon (MOS) transistor in the passive mode is considered. Several surface-defect formation processes are observed. The role of molecular hydrogen in the undergate oxide of the MOS transistor and “hot” electrons forming in the silicon surface region is shown.

Abstract Electron wave functions in the conduction band of zero-gap HgCdTe alloy are calculated in the Coulomb acceptor field. The resonant-state energies are determined.

Abstract The process of the Pd-assisted etching of silicon in a solution containing HF and H2O2 is investigated. It is shown that the morphology of the forming layers is affected by such factors as the etching duration and solution temperature. It is shown that Pd nanoparticles remain on the walls and bottom of the pores in the course of Pd-assisted etching. Such a structure, as is shown in earlier

Abstract A new method for depositing carbon films by the thermal decomposition of carbon tetrachloride (CCl4) in a hydrogen flux in a reactor for metal-organic chemical vapor deposition (MOCVD) at atmospheric pressure is developed. From the results obtained by Raman spectroscopy, it can be conceived that the carbon layers produced by this method are the disordered nanocrystalline graphite. It is shown

Abstract The phonon modes of quantum-cascade heterostructures based on binary and ternary semiconductor compounds are simulated. The dependences of the frequencies of the structure interface phonon modes on the wave vector in the layer plane and on the phase shift in the superlattice period are calculated. It is found that the range of variation in the quantum energy of phonon modes of the GaAs/Al0

Abstract The results of experimental and theoretical investigations of terahertz-emission-spectrum tuning by means of uniaxial stress of a silicon crystal doped with shallow bismuth donors are presented for the case of intracenter optical excitation. The frequency tuning of two emission lines of the bismuth donor is shown for the case of uniaxial strain along the [001] crystallographic direction. The

Abstract The spatial and temporal dynamics of the optical loss and carrier density in the heterostructure of a semiconductor laser with a segmented contact are studied using an optical pump–probe technique based on the injection of probe radiation with a wavelength of 1560 nm into a semiconductor laser chip under study that is based on an AlGaAs/InGaAs/GaAs heterostructure and emits at wavelength of

Abstract Highly transparent ZnO|PEDOT:PSS inorganic|organic hetero-junction were fabricated using thin (300 nm in thickness) ZnO prepared via radio frequency (RF) magnetron sputtering at different oxygen flow rates ranging from 0 to 20 sccm. The AFM images revealed that the average grain size decreased with increasing oxygen flow rate. In addition, the results of this analysis showed that with an increase

Abstract The possibility of the nonresonance phase conjugation of light occurring in an excited semiconductor medium is shown theoretically and experimentally. In epitaxial ZnO films pumped with a nitrogen laser at room temperature, the induced phase conjugation of light in the visible and infrared spectral regions is detected. The dependences of the phase-conjugation signal intensity on the incident

Abstract The intrinsic transverse-magnetic modes of graphene with spatial dispersion are investigated theoretically in the hydrodynamic regime in a terahertz frequency range. It is revealed that spatial dispersion is caused by the diffusion electron-transport mechanism due to the spreading of electron-concentration gradients under the effect of pressure in an electron liquid. The cases of a screened

Abstract In this paper, surface-enhanced Raman scattering (SERS), a key application of plasmonics, is investigated. Since this technique is based on the interaction of light with nanostructures with proper dimensions and material, finding proper materials and calculating optimized nanostructure dimensions affects its output, greatly. In this report, after a general investigation of this application

Abstract The luminescence properties of arrays of spatially ordered self-assembled solitary Ge(Si) nanoislands and their groups, including those embedded in two-dimensional photonic crystals, are studied. It is shown that the incorporation of an array of ordered solitary Ge(Si) islands and their groups into photonic crystals results in an increase in the intensity of their photoluminescence signal

Abstract We present a study of Shubnikov–de Haas (SdH) oscillations at temperatures of (2.2–10) K in magnetic fields up to 2.5 T in the HgCdTe/HgTe/HgCdTe heterostructure for a wide (20.3 nm) HgTe quantum well with an inverted energy band structure. The analysis of the temperature dependence of SdH amplitude in weak fields, in a region of doubly degenerate magnetoresistance peaks, led us to the value

Abstract The deposition temperature of the bath in chemical-bath-deposited cadmium-sulfide thin films can directly affect the optical, electrical, structural as well as morphological properties of deposited thin films. The reporting work discusses the properties of chemical-bath-deposited cadmium-sulfide thin films deposited under steady chemical-bath temperature conditions at both 40 and 80°C and

Abstract Vanadium dioxide (VO2) undergoes a reversible metal-insulator transition at low temperature, which has wide range of applications in smart windows and infrared detectors. However, the preparation of VO2 films with controllable phase on glass substrate is still limited. In this paper, it is shown that B-phase can be transformed into M-phase with monoclinic structure by inserting TiO2 buffer

Abstract The effect of atomic composition on the rate of the plasma-chemical etching of silicon nitride in high-power transistors based on an AlGaN/GaN heterojunction is studied. It is shown how the subsequent process of its plasma-chemical etching depends on the configuration of the incorporation of hydrogen impurity atoms into the molecular structure of silicon nitride deposited in the plasma. The

Abstract The processes of crystallization of amorphous germanium films of various thicknesses and multilayer germanium/silicon nanostructures under isothermal annealing (T = 440°C) were studied. Samples were grown on glass substrates using the method of plasma-chemical deposition. The phase composition of the structures was determined from the analysis of Raman spectra. It was found that 200 nm thick

Abstract Photodiodes based on solid solutions in the GaSb–InAs system are for the first time applied to study the spectral characteristics of single and coupled whispering-gallery-mode (WGM) lasers emitting in a range of 2.2–2.3 μm. The capacity of photodiodes with a photosensitive area 2.0 mm in diameter is C = 520 pF at U = –2 V, which corresponds to a time constant of τ = 53 ns. It is shown that

Abstract The emission properties of Ge layers grown on Si(001) substrates and doped with Sb to different levels are studied by means of steady-state and time-resolved photoluminescence spectroscopy. It is shown that the peak of the steady-state photoluminescence intensity of n-Ge/Si layers at room temperature is observed at an Sb concentration close to the level of the equilibrium solubility of Sb

Abstract Recent experimental and theoretical data on modification of the atomic and electronic structures of the surface of different III–V semiconductors by electrolyte solutions are reviewed. The interrelation between chemical reactions occurring at semiconductor/electrolyte interfaces, the charge transfer between the semiconductor and the solution, and corresponding modifications of the atomic and

Abstract The atomic and electronic structures of reconstructions with the symmetry (2 × 4), (4 × 2), c(4 × 4), and (4 × 3) on the (001) surface of GaSb and InSb semiconductors are investigated by the projector augmented-wave method. It is shown that the reconstruction β2(2 × 4) is stable on the GaSb(001) surface in the cation-rich limit, while the α2(2 × 4) reconstruction has the lowest energy in the

Abstract A method is developed for analyzing spontaneous-emission modification in cylindrically symmetric structures. A matrix method is developed for cylindrical structures. General expressions for the radiative-recombination rate are derived for an emitter placed at any point on the structure. Quantitative indicators for estimating radiative-recombination enhancement and suppression are determined;

Abstract Gallium-nitride nanorods with a diameter of 15–40 nm and length of 50–150 nm are synthesized in monodisperse spherical mesoporous silica particles (MSMSPs) by high-temperature annealing of the Ga2O3 precursor in ammonia. The template material (a-SiO2) is selectively removed by etching the composite MSMSP/GaN particles with HF to give individual GaN nanorods. It is shown that the size of the

Abstract A new Pd|HfO2|AlGaN|GaN metal-oxide-semiconductor (MOS) enhancement-mode high electron mobility transistor (HEMT) is fabricated with low-temperature sensitization, activation, electroless-plating, and two-step gate-recess approaches. Experimentally, a high positive threshold voltage Vth of 1.96 V, a very low gate leakage IG of 6.3 × 10–8 mA/mm, a high maximum extrinsic transconductance gm

Abstract A model of a heterostructure consisting of a silicon-carbide single layer formed on a massive silicon substrate is proposed. The problem of the adsorption of alkali metal atoms and halogen atoms on the carbon and silicon surface atoms of a 2D SiC/Si heterostructure is considered. Analytical estimates for charge transfer and the adsorption energy are reported.

Abstract Some of the III–V semiconductor used in various devices suffer from the surface high density of states limiting their application. This study compares and evaluates five different ammonium sulfide passivation methods on GaAs surface with the aim to enhance the electrical characteristics of Au|n-GaAs Schottky junction. Wet chemical passivation of the n-GaAs surface was carried out by dipping

Abstract We analyze the asymmetric delta-doping dependence of nonlinear electron mobility μ of GaAs|InxGa1 –xAs double quantum-well pseudo-morphic modulation doped field-effect transistor structure. We solve the Schrodinger and Poisson’s equations self-consistently to obtain the sub-band energy levels and wave functions. We consider scatterings due to the ionized impurities (IMP), alloy disorder (AL)

Abstract The growth of AlGaInSbAs solid solutions on InAs substrates from the liquid phase in a temperature-gradient field is discussed. The calculation of parameters is performed, and the luminescence properties and spectral characteristics of AlGaInSbAs solid solutions isoperiodic to InAs substrates are investigated. The heterophase equilibria in the Al–Ga–In–Sb–As system are analyzed in the scope

Abstract The behavioral features of the spectra of impedance components and electric module for copper-doped polycrystalline zinc-sulfide layers are investigated. The dispersion of the frequency dependences of the electrical parameters corresponding to the distribution of the relaxation time is established. An equivalent sample circuit that includes a constant phase element and describes electric transport

Abstract The impedance and capacitive properties of Pd/oxide/InP structures are investigated at 300 K in the frequency range of 10–1–10–5 Hz in air and in a nitrogen–hydrogen gas medium. The characteristics of structures in both media are interpreted based on a parallel RC-chain model with series resistance. The structure resistance decreases in the presence of hydrogen by three orders of magnitude

Abstract The results of studying the frequency and temperature dependences of the ac electrical conductivity of FeGaInSe4 crystals are presented. It is found that the systematic feature σ ∝ f s (0.1 ≤ s ≤ 1.0) is satisfied for the electrical conductivity at the temperatures under study in the frequency range f = 5 × 104–106 Hz. The activation energies are determined from the temperature dependences

Abstract Resistive-type structures based on gallium-oxide films are studied. The Ga2O3 films are produced by radio-frequency magnetron-assisted sputtering of a β-Ga2O3 (99.9999%) target onto unheated sapphire substrates with preliminarily deposited platinum electrodes. The data on the structure and phase composition of the films are obtained immediately after sputtering and after annealing in argon

Abstract In a particular case of Au-catalyzed InxGa1 –xAs nanowires, wide compositional tuning has been obtained using metal organic vapor-phase epitaxy, which remains difficult for molecular beam epitaxy. InxGa1 –xAs nanowires are demonstrated with x = 0.5, grown by Au-catalyzed molecular beam epitaxy via the vapor–solid–solid mode at a low temperature of 220°C. Low-temperature growth suppresses re-evaporation

Abstract The spectroscopic ellipsometry method is used to investigate the optical properties of PbSe nanostructured thin films formed by the chemical deposition method. Function d2ε/dω2 formed by numerical differentiation of experimental data of the dielectric function ε/ω is used for better structural resolution of the interband transitions and the determination of critical points. Theoretical fitting

Abstract The equilibrium transport of atomic carbon between the Rh surface and bulk, which controls the kinetics of the phase transition resulting in graphene growth or destruction, is investigated. The difference between the activation energy Es1 of atomic-carbon dissolution and the energy E1s of its segregation from the bulk to the surface is found to be ΔE = 0.7 eV. The temperature dependence of