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Polycrystalline and epitaxial iron silicide (FeSi) films with thicknesses of 3.2–20.35 nm are grown on a Si(111) substrate using solid-phase and molecular-beam epitaxy at 350°C, as confirmed by X-ray diffraction data. Morphological studies reveal that the films grown by solid-phase epitaxy are continuous and smooth with a root-mean-square roughness ranging from 0.4 to 1.1 nm, while those grown by molecular-beam epitaxy exhibit increased roughness and consist of coalesced grains with sizes up to 1 μm and a pit density of up to 1 × 107 cm–2. In the case of solid-phase epitaxy, an increase in the thickness leads to incomplete silicide formation and the emergence of a layer of disordered iron silicide with a thickness ranging from 10 to 20 nm, possibly with an excess of iron. This is confirmed by a change in the nature of the temperature dependence of the resistivity ρ from semiconductor to semimetallic, which leads to a decrease in the resistivity by 1.5–2 times. The nonmonotonic character of the temperature dependence of the resistivity ρ(T) for an ultrathin FeSi film with a thickness of 3.2 nm is identified, exhibiting a maximum around 230–240 K, a rising segment from 160 to 65 K with Eg = 14.8 meV, and further unsaturated growth down to 1.5 K. As the thickness of the FeSi films grown by molecular-beam epitaxy increases, the minimum and maximum are not observed, but the nonmonotonic trend of ρ(T) with decreasing temperature and the opening of the band gap Eg = 23 meV are preserved. The possible reasons for the observed effects in the ρ(T) dependences are considered. An anomalous Hall effect is detected in ultrathin and thin FeSi films grown by solid-phase and molecular-beam epitaxy, respectively, which confirms the weak ferromagnetic properties of the films. The results demonstrate the feasibility of growing and controlling the properties of ultrathin and thin FeSi films on silicon using methods of solid-phase and molecular-beam epitaxy, providing them with unique transport and magnetic properties not present in single crystals. [ABSTRACT FROM AUTHOR]

Mg2Si film 350–600 nm thick was formed on Si(111) substrate by ultrafast reactive deposition of Mg. Then 10–15 nm thick films of FeSi or CrSi2 were grown as cover layers on Mg2Si by codeposition of Fe/Si or Cr/Si. In comparison with bare Mg2Si/Si film, the measured transparency losses in 0.1–1.1 eV range are ∼17–25 and 10–35% for the samples with the FeSi and CrSi2 layers, respectively. The measured at room temperature resistivity is ∼0.24 mΩ cm for FeSi and 1.7 mΩ cm for CrSi2. The photoresponse of structures FeSi/Mg2Si/Si and CrSi2/Mg2Si/Si illuminated with the light filtered by a silicon plate demonstrate the spectral sensitivity in the range 980–1200 nm and peak intensity ∼255 and ∼620 μA/W respectively. [ABSTRACT FROM AUTHOR]

Epitaxial and polycrystalline films of iron (Fe), chromium (Cr), and calcium (Ca) silicides of various thicknesses (from 3.2 to 380 nm) were grown on silicon and sapphire substrates in ultrahigh vacuum by three methods (solid-phase epitaxy, reactive epitaxy and molecular beam epitaxy). The crystal structure and matching with the silicon lattice were determined for them using the X-ray diffraction method. A comparative analysis of Raman scattering spectra and far-IR spectroscopy spectra showed that films of semiconductor silicides have the strongest Raman peaks, and the detected shifts in their positions are caused by distortions in the silicide lattices. It has been established that in films of iron and chromium monosilicides at a fixed laser excitation wavelength ( nm) and a power of 3.4 mW, the strength of the Raman peaks decreases with decreasing film thickness and they disappear completely at a thickness below 10 nm. Chromium trisilicide films were grown on single-crystal sapphire, which made it possible for the first time to detect for it active Raman phonons at nm and a power of 0.42 mW at wave numbers 214.3 and 273.1 cm . The studied films of transition metal monosilicides are of significant interest from the perspective of their possible use as materials for thermoelectronics and spintronics, and systematized information on active Raman phonons and IR active phonons will make it possible to quickly determine the type of phase formed immediately after film growth. [ABSTRACT FROM AUTHOR]

We simulate the conjugation of crystal lattices of two-dimensional Mg2Si layers with atomically clean Si(001)2×1 and Si(110)"16×2" surfaces. Thick films are grown by molecular-beam epitaxy (MBE) through the formation of Ca2Si seed layers. For a Si(001) substrate, three different silicides are formed in a 140-nm thick film at a temperature of T = 300°C at a Ca-to-Si deposition rate ratio of 4.7: Ca2Si, CaSi, and hR3-CaSi2 with comparable contributions. With a decrease in the MBE-growth temperature to 250°C and a Ca-to-Si deposition-rate ratio of 8.4, a polycrystalline Ca2Si film is formed on Si(110) with the minimal contribution from CaSi. Polycrystalline and epitaxial Ca2Si films with thicknesses from 22 to 114 nm are grown on Si(111) substrates by the sacrificial-template method and MBE growth at a temperature of 250°C and different ratios of Ca and Si deposition rates (4.0–20.0). The minimum deposition-rate ratio ensures single-phase growth with the Ca2Si(100)/Si(111) epitaxial ratio; as it increases from 7.3, polycrystalline films grow with three orientations on Si(111): Ca2Si(100), Ca2Si(110), and Ca2Si(111). In Ca2Si films, regardless of their structure, the fundamental transition is masked by the Urbach edge in the photon-energy range of 0.78–1.0 eV, and then the second direct interband transition is identified (E2d = 1.095 ± 0.1 eV). [ABSTRACT FROM AUTHOR]

A nanocrystalline Ca2Si film on Al2O3(0001) is formed for the first time by converting a sacrificial 2D Mg2Si template into a Ca2Si seed layer with the preliminary formation of an amorphous 2D silicon layer. A Ca2Si seed layer on a sapphire substrate facilitates the growth of oriented Ca2Si films by molecular-beam epitaxy (MBE) at a temperature of 250°C, for which one epitaxial ratio is observed, Ca2Si(211)/Al2O3(0001). Studies of the optical properties and parameters of the band structure of Ca2Si on sapphire reveal the nature of the fundamental direct transition with an energy of 0.88 ± 0.01 eV. Direct interband transitions are observed in the band structure of Ca2Si: at 0.88, 1.16, 1.49, and 1.61 eV with increasing oscillator strength. At photon energies from 0.78 to 0.88 eV, the Urbach tail on defects in Ca2Si nanocrystals makes the main contribution to absorption. Absorption at grain boundaries is observed at photon energies from 0.6 to 0.78 eV, and at free carriers, at energies below 0.6 eV. The results obtained are important for optoelectronics in the infrared (IR) region of the spectrum. [ABSTRACT FROM AUTHOR]

The magnetic properties of nanoobjects of nonmagnetic substances based on silicon and transition metal (iron) are considered. It is found that a system of -FeSi nanorods with a mean height of 6.6 nm and lengths from 50 to 200 nm is formed by deposition of iron with 5.22 monolayers in ultrahigh vacuum on a vicinal silicon surface Si(111)-4 followed by annealing at a temperature of C. Soft ferromagnetic loops with a coercive force from 90 to 180 Oe, which persist up to a temperature of 300 K, are observed in nanorods. It is found that easy magnetization axis is perpendicular to the nanorods, while the hard magnetization axis is parallel to them. This type of nanoobjects is promising for developing spintronic devices within the planar silicon technology. [ABSTRACT FROM AUTHOR]

Photonic crystals based on amorphous SiO2 nanospheres have been obtained in four-component H2O–Si(OC2H5)4–NH3–EtOH systems at a constant initial volume (100 mL), a constant molar ratio of NH3:Si(OC2H5)4 = 10 : 1, and varied molar ratio of H2O–Si(OC2H5)4 (x1) and H2O–EtOH (x2) within the range of 30–110 and 0.4–2.8, respectively. The increase in water concentration and simultaneous decrease in the alcohol concentration in the initial mixture have resulted in the reduction of mean diameter of the SiO2 spheres from 440 to 270 nm. The curves of the correlation curves between effective diameter of the nanospheres– and the H2O–Si(OC2H5)4 and H2O–EtOH molar ratio have shown two regions with different slopes: for the samples obtained at low H2O–Si(OC2H5)4 and H2O–EtOH molar ratios for these obtained at [H2O] : [Si(OC2H5)4] > 50, [H2O] : [EtOH] > 1. Correlations between the size of the nanospheres of oligomerized SiO2, the initial rate of the process, and the dielectric constant of the initial mixture have been found. The spectral parameters of the photonic crystals obtained on the basis of the amorphous SiO2 spheres have been affected by the H2O–Si(OC2H5)4 and H2O–EtOH molar ratios in the initial mixtures. [ABSTRACT FROM AUTHOR]

Real-time thermal analysis is used for the synthesis of silica globules. The rate of the reaction of sol synthesis is determined. The reaction order is found, depending on the concentration of water, and the kinetic and diffusion regions are identified. Dried (not annealed) samples are studied via DSC. The dynamics of ethanol and water evolution from the samples is studied in analyzing the heating and cooling curves. Structural phase transformations of the formation of β-cristobalite and its transition to the α-form are observed. The dependence of the amorphousness of the sample on the amount of water in the solid phase is determined. It is found that when the water–TEOS molar ratio is less than fifty, the process proceeds slowly and hydrolysis is incomplete. An explanation of this pattern is proposed. A reaction equation for the kinetic region is determined for the case when the indicated molar ratio is more than 100. A general chemical formula for the main structure of a globule's core is proposed, with allowance for the presence of cristobalite fragments in all samples. Based on an analysis of this formula, a condition is found for the case when the hexagonal ring cannot be the basis of the structure, and the amount of chemically retained water can be determined. A stoichiometric formula for the product that forms in the diffusion region is obtained. [ABSTRACT FROM AUTHOR]

The interaction of porous silicon (PS) with aqueous solutions of Fe(NO3)3 with different molar (M) concentrations causes introduction of iron ions into silicon pores (PS-Fe), formation of adsorbed iron coatings with different thicknesses, and an increase in the stability of PS layers, which is important for development of device structures based of PS. To treat PS layers with solutions by the immersion method, it is necessary to determine how this affects the spectral composition and intensity of photoluminescence (PL), as well as the kinetics of PL changes during long storage under atmospheric conditions. Upon treatment of freshly prepared PS by immersion into in a Fe(NO3)3 aqueous solution, it was found that, after short-term storage (up to 5 days) of the PS samples, the PL intensity increases by 7.5 and 3-3.6 times at low (0.2 M) and high (0.7-0.8 M) concentrations of Fe(NO3)3, respectively, compared to the PL intensity of an untreated PS layer. After long-term storage (4 months), the PL intensity of PS-Fe samples with concentrations of 0.1-0.2 and 0.7-0.8 M was observed to considerably increase (by 8-18 times) with unchanged position of the PL peak with respect to untreated PS. However, at the Fe(NO3)3 concentration of 0.3 М, the PL intensity decreases and the PL peak shifts to the blue, which is explained by incomplete coverage of the PS surface by an adsorbed iron layer. The kinetics of PL spectra during long-term storage is analyzed, and a model is proposed to explain the PL intensity and spectral composition. [ABSTRACT FROM AUTHOR]

The main mechanisms of the visible electroluminescence (EL) of porous silicon are reviewed. Characteristics of photoluminescence and EL of diode structures based on porous silicon are compared. Metals having a smaller value of the electron work function (3.6 eV, Mg) than do Al and Au are proposed as the material for making contacts in such diode structures to increase the efficiency of their EL in the visible region of the spectrum. The main problems and prospects of light-emitting devices based on porous silicon are formulated. [ABSTRACT FROM AUTHOR]

A strong nonlinear increase in the photoluminescence intensity under laser excitation at room temperature is found for porous silicon obtained by anodic oxidation. It is shown that the maximum photoluminescence intensity corresponds to samples of anodically oxidized porous silicon in the intermediate oxidation state. Laser excitation is found to increase the intensity of vibrational modes in the О-SiH, Si-O-Si, and Si-O-H configurations with respect to the Si-H mode intensity in IR absorption spectra. It is experimentally confirmed that the oxide structure on the surface of silicon crystallites and the structure of the Si/SiO interface determine to a great extent the photoluminescence characteristics. [ABSTRACT FROM AUTHOR]

By using solid phase epitaxy of thin Fe films and molecular beam epitaxy of Si, a p+ -Si/p-Si/β-FeSi2 nanocrystallites/n-Si(111) diode structure was fabricated. Transmission electron microscopy data confirmed a well-defined multilayered structure with embedded nanocrystallites of two typical sizes: 3-4 and 15-20 nm, and almost coherent epitaxy of the nanocrystallites with the Si matrix. The diode at zero bias conditions exhibited a current responsivity of 1.7 mA/W, an external quantum efficiency of about 0.2%, and a specific detectivity of 1.2 x 109 cm x Hz1/2/W at a wavelength of 1300 nm at room temperature. In the avalanche mode, the responsivity reached up to 20 mA/W (2% in terms of efficiency) with a value of avalanche gain equal to 5. The data obtained indicate that embedding of β-FeSi2 nanocrystallites into the depletion region of the Si p-n junction results in expansion of the spectral sensitivity up to 1600 nm and an increase of the photoresponse by more than two orders of magnitude in comparison with a conventional Si p-n junction. Thereby, fabricated structure combines advantage of the silicon photodiode functionality and simplicity with near infrared light detection capability of β-FeSi2. [ABSTRACT FROM AUTHOR]

The structural and optical properties of thin Ge films deposited onto semiconducting and insulating substrates and modified by pulsed laser radiation are studied. The films are deposited by the sputtering of a Ge target with a low-energy Xe ion beam. Crystallization of the films is conducted by their exposure to nanosecond ruby laser radiation pulses (λ = 0.694 μm) with the energy density W = 0.2−1.4 J cm. During pulsed laser treatment, the irradiated area is probed with quasi-cw (quasi-continuous-wave) laser radiation (λ = 0.532 and 1.064 μm), with the reflectance recorded R( t). Experimental data on the lifetime of the Ge melt are compared with the results of calculation, and good agreement between them is demonstrated. Through the use of a number of techniques, the dependences of the composition of the films, their crystal structure, the level of strains, and the reflectance and transmittance on the conditions of deposition and annealing are established. [ABSTRACT FROM AUTHOR]

The electroluminescence efficiency of silicon light-emitting diode structures with several layers of β-FeSi nanocrystallites embedded in the p-n junction is investigated. The nanocrystallites were formed by either solid-phase epitaxy or a combination of reactive and solid-phase epitaxy. For the structures in which the nanocrystallites were formed by the combined method, electroluminescence is observed only at low temperatures (below 70K). This is indicative of a high concentration of defects acting as nonradiative-recombination centers. For the structures with nanocrystallites formed by solid-phase epitaxy, intense electroluminescence is observed up to room temperature. The dependence of the electroluminescence intensity on the size of the nanocrystallites is studied. [ABSTRACT FROM AUTHOR]

A thin iron film deposited at the rate of 10 nm/sec on the Si(001) surface and a sandwich structure silicon/iron/Si(111) are studied by Surface Magneto-Optic Kerr Effect, High Resolution Electron Microscopy and X-ray Photoelectron Microscopy methods. The phases present in the structures are identified. Both structures are non-uniform. The ultra-fast-deposited film is magnetically hard ( H=45 Oe), it contains the silicide FeSi. The XPS line shift by +0.55 eV with respect to the pure iron 2p 3/2 level is attributed to FeSi. The cross-section image of the sandwich structure shows the presence of enhanced-intermixing channels crossing the Si-rich layer. Iron atoms are the main diffusion species both at the Fe/Si(111) and Si/Fe interfaces. The nature of the volume defect and internal stresses in the transforming iron silicides and their effects on material intermixing and film growth process are discussed. [ABSTRACT FROM AUTHOR]

Formation of calcium silicide on three types of templates: Si(111)7 × 7, 2D Mg2Si, and 3D Mg2Si, was studied during Ca deposition at 120 °C in situ by Auger and electron energy loss spectroscopy, and by differential optical reflectance spectroscopy. A continuous Ca2Si layer is formed on 2D and 3D Mg2Si templates; but, on an atomically clean silicon surface (Si(111)7 × 7), a mixture of Ca2Si with another Ca silicide was found. The growth of a Si cap layer over the Ca silicide layers at about 100 °C studied by in situ methods demonstrated the full embedding of Ca silicide in amorphous silicon, independent of the used template. Transmission electron microscopy, Rutherford backscattering spectrometry, atomic force microscopy, and electrical characterization of Schottky junctions revealed the Ca2Si and Mg2Si nanoparticles and the redistribution of Mg and Ca during the silicon cap growth and its effect on the electronic properties of the structures. Reproduction of the experiments on higher doped and better purity substrates is needed to understand better the role of Mg- and Ca-related defects, and defects of silicon generated by the growth process. [ABSTRACT FROM AUTHOR]

Single-crystalline silicon is implanted by magnesium ions at room temperature and then subjected to pulsed ion-beam annealing. The surface morphology, crystallinity, and optical properties of the implanted silicon are studied before and after annealing. It is shown that ion implantation makes a near-surface layer of silicon about 0.1 m thick amorphous. Pulsed nanosecond ion-beam annealing results in silicon recrystallization and the formation of crystalline magnesium silicide precipitates. Optimal values of the implantation dose and pulse energy density for the formation of magnesium silicide precipitates in the near-surface layer of silicon are found. [ABSTRACT FROM AUTHOR]

The electronic, geometric, and magnetic structure of nanofilms of the β phase of iron disilicide FeSi with the (001), (100), and (010) surfaces have been simulated through density functional calculations. A substantial reconstruction of the (001) surface terminated with silicon atoms has been observed, which was accompanied by an increase in the surface symmetry and appearance of 'squares' of silicon atoms. Analysis of the electron density of states (DOS) and spin DOS projected on the contributions of layers of atoms (LSDOS) indicates that all plates have metallic properties. The main contribution near the Fermi level comes from the surface iron layers and it decreases rapidly with an increase in the distance from the surface of the plate. Analysis of the calculated effective magnetic moments of atoms shows that the surface layers in the plates have a significant magnetic moment, in particular, iron layers on the (001) surface (1.89 μ/atom). The moments of atoms decrease rapidly with an increase in their distance from the surface. The electron and geometric regions of a (001)Si/FeSi interface have been studied. Analysis of the LSDOS shows that the surface conducting state mainly determined by the contribution from the near-surface silicide layers is implemented in this region. The possibility of the formation of the perfect and sharp Si/FeSi interface has been demonstrated. [ABSTRACT FROM AUTHOR]

This paper reports the results of the study of hydrothermal precious opals. It was established that, in terms of their nanostructure and formation conditions, the hydrothermal opals differ from exogenic precious opals. They are made up of small globules and do not show any structuring of their nanoparticles on the basis of closest packing, which is typical of exogenic precious opals. During their formation, these opals were subjected to pneumatolytic annealing—they experienced the impact of a high-temperature vapor under elevated pressure. The influence of the thermal effect led to the formation of two-dimensional photonic band gaps in the chaotic opal matrix. These bands are composed of sheets whose cells were formed owing to the thermal effects according to the principle of “Benard cells.” Precisely these structured blocks and thin films are responsible for the spectral dispersion of light and iridescence. [ABSTRACT FROM AUTHOR]

The effect of pulsed ion-beam annealing on the surface morphology, structure, and composition of single-crystal Si(111) wafers implanted by chromium ions with a dose varying from 6 × 1015 to 6 × 1016 cm−2 and on subsequent growth of silicon is investigated for the first time. It is found that pulsed ion-beam annealing causes chromium atom redistribution in the surface layer of the silicon and precipitation of the polycrystalline chromium disilicide (CrSi2) phase. It is shown that the ultrahigh-vacuum cleaning of the silicon wafers at 850°C upon implantation and pulsed ion-beam annealing provides an atomically clean surface with a developed relief. The growth of silicon by molecular beam epitaxy generates oriented 3D silicon islands, which coalesce at a layer thickness of 100 nm and an implantation dose of 1016 cm−2. At higher implantation doses, the silicon layer grows polycrystalline. As follows from Raman scattering data and optical reflectance spectroscopy data, semiconducting CrSi2 precipitates arise inside the silicon substrate, which diffuse toward its surface during growth. [ABSTRACT FROM AUTHOR]

Studies of the structure and magnetic properties of layers formed on nonmagnetic substrates by laser powder fusing (LPF) showed that crystalline phases are separated from initial powders of bronze, inconel (IN 625), and PGSR-4with the transformation of nonmagnetic materials to soft ferromagnets. The fused bronze powder layer exhibits soft ferromagnetic properties with two types of magnetic domains with the Curie temperatures of 80 and 300 K and a coercivity to 90 Oe at 300 K; in layers based on In625 and PGSR-4, only one type of magnetic domains with the Curie temperatures of 260-270 K is formed, which provides soft ferromagnetic properties at 4 К and the paramagnetic transition at 300 K. [ABSTRACT FROM AUTHOR]

Consecutive plasma-epitaxial synthesis on silicon wafers is used for the first time to fabricate monolithic nanoheterostructures with embedded nanocrystals (NC) of chromium disilicide (Si–NC CrSi2–Si). It is found that, initially, nanoislands form on the surface and within a coating layer of silicon, followed by the formation of small (10–15 nm) nanocrystals of semiconducting chromium disilicide (CrSi2) at a high occupation density ((2–3)⋅1011 cm–2). During formation of silicon-silicide-silicon heterostructures, CrSi2 nanocrystallites “float up” into the near surface area of the covering silicon layer. [ABSTRACT FROM AUTHOR]

The initial stages of room-temperature Mg film growth of Si (111) were studied using low-energy electron diffraction, electron energy-loss spectroscopy, and differential reflectance spectroscopy. In the studied range of magnesium film thickness ( h = 0–0.2 nm), the formation of semiconductor magnesium silicide (Mg2Si), which is a promising material for silicon-silicide thermocouples, was detected. At small thicknesses of the deposited film, identical Mg2Si clusters are formed. An increase in the number of Mg atoms results in the formation of two-dimensional and then three-dimensional Mg2Si islands. Spectra of the optical response function δΛ″θ were measured for all structures; these spectra represent a characteristic of opticalproperties of these structures. [ABSTRACT FROM AUTHOR]

Methods of low-energy electron diffraction, measurements of the Hall effect in situ, atomic-force microscopy, and high-resolution transmission electron microscopy were used to study the formation of iron silicide islands on the Si(100)–(2×1) surface and overgrowth of these islands with silicon; the electrical properties and structure of silicon with buried iron silicide nanocrystallites were studied. The best crystal quality of the continuous single-crystal silicon layer and the minimum roughness of its surface were observed at the silicon growth temperature of 700°C and the layer thickness of 100 nm. A model of growth of silicon over the ironsilicide nanocrystals is suggested. Two types of formed nanocrysrallites were found: small nanocrystallites (5–6 nm) of β-FeSi2 and large nanocrystallites (30–50 nm) of γ-FeSi2. The good agreement between the electrical parameters of silicon with buried iron disilicide nanocrystallites and those of atomic-clean silicon confirmed that there is minimum scattering of charge carriers at nanocrystallites in the temperature range of 300–540 K. [ABSTRACT FROM AUTHOR]

Low-energy electron diffraction and differential reflectance spectroscopy are used to study the self-formation of chromium disilicide (CrSi2) nanoislands on a Si(111) surface. The semiconductor properties of the islands show up even early in chromium deposition at a substrate temperature of 500°C, and the two-dimensional growth changes to the three-dimensional one when the thickness of the chromium layer exceeds 0.06 nm. The maximal density of the islands and their sizes are determined. The MBE growth of silicon over the CrSi2 nanoislands is investigated, an optimal growth temperature is determined, and 50-nm-thick atomically smooth silicon films are obtained. Ultraviolet photoelectron spectroscopy combined with the ion etching of the specimens with embedded nanocrystallites demonstrates the formation of the valence band, indicating the crystalline structure of the CrSi2. Multilayer epitaxial structures with embedded CrSi2 nanocrystallites are grown. [ABSTRACT FROM AUTHOR]

The optical properties of ultrasmall ordered indium and chromium quantum dots of identical size (magic clusters) in the In/Si(111) and Cr/Si(111) systems have been studied by differential reflection spectroscopy (DRS). Using the DRS data, the character of the magic clusters of each type has been elucidated. It is established that the magic clusters of chromium formed in the Cr/Si(111) system represent nanocrystals of chromium silicide (Cr/Si(111) is a reactive system featuring chemical interaction between the metal and the silicon substrate, which leads to silicide formation). The magic clusters of indium formed in the nonreactive In/Si(111) system represent a surface phase. [ABSTRACT FROM AUTHOR]

A simple and inexpensive device rather sensitive to studies of magnetic properties of very thin (0.5–0.6 nm) ferromagnetic films by the surface magnetooptic Kerr effect (SMOKE) method in ultrahigh vacuum (UHV) conditions is described. The system is intended for measuring both longitudinal and transversal Kerr effects. The special vacuum-tight electromagnet system of the SMOKE device is quite compatible with other surface-sensitive methods. When an additional external magnet system is used, the same optical and electronic system can be also employed for ex situ investigations. Examples demonstrating the high sensitivity of this setup and its efficiency during studies of the magnetic anisotropy are given. [ABSTRACT FROM AUTHOR]

Quasiballistic electron transport in three-dimensional microconstrictions in a longitudinal magnetic field is studied. The case where the quantization of the conductance is destroyed by an impurity located in the microconstriction is investigated. The transmission coefficients and a formula for the conductance of such a microconstriction are found. It is shown that the dependence of the conductance G(E) on the electron energy has kinks at the threshold of the steps for which impurity scattering is strong. These kinks contain a pronounced vertical segment of the curve G(E). [ABSTRACT FROM AUTHOR]

The in situ Hall effect measurements at room temperature showed that formation of the atomically clean Si(111) 7 × 7 surface as a result of high-temperature annealing (T = 1250°C, t = 120-180 s) of n-Si reverses the majority carrier sign at the surface, and a hole-enriched layer is formed at the p-Si surface. The different dynamics of Hall and resistivity voltage variations within the first monolayer of iron adsorbed onto substrates with ap-n junction or with a hole-enriched layer is not related to conduction over the adsorbed layer. Conduction in the Fe layer of thickness exceeding three monolayers is caused in both cases by the transport of electrons with densities 2 × 10[sup 13] -2 × 10[sup 14] cm[sup -2] and mobilities 65-90 cm² (V s). [ABSTRACT FROM AUTHOR]

An analysis is made of ballistic electron transport in three-dimensional microconstrictions of elliptic cross section located in an arbitrarily oriented magnetic field. The model of a parabolic confinement potential is used to obtain and analyze the dependence of hybrid frequencies on the magnitude and direction of the magnetic field. An expansion of the conductance as a Fourier series is obtained and used to study Aharonov-Bohm and Shubnikov-de Haas oscillations as a function of the field and the stepped quantization structure of the conductance. A possible explanation is given for the experimentally observed effect of conductance quantization at fairly high temperatures. [ABSTRACT FROM AUTHOR]

The design of a simple pulse-type evaporator ensuring a high rate (up to ∼104 nm/s) of deposition of thin films (0.01–100 nm thick) onto a solid surface in ultrahigh vacuum is described. The evaporation pulse is created by discharge of a capacitor bank via a fast-response evaporator produced from a tungsten foil. Results illustrating the efficiency of this device are presented. [ABSTRACT FROM AUTHOR]

Spectral and integrated photoconductivities in chromium-disilicide epitaxial films grown on singlelayer silicon substrates have been studied in the photon energy range 0.5 - 1.6 eV. The region of the photoconductivity maximum observed at 1.23 eV corresponds to the third direct interband transition in chromium disilicide at 0.9 - 0.95 eV. Possible reasons for the weak photoconductivity signal in the region of the fundamental absorption edge are analyzed. [ABSTRACT FROM AUTHOR]