Vacuum
This paper investigates theoretically the magnetoconcentration effect in an abrupt heterostructure on the basis of non-degenerate semiconductors with an intrinsic conductivity in the case when a recombination of non-equilibrium current carriers occurs at the heterostructure interface. The influence of the interfacial recombination velocity on the current-voltage characteristics of the heterostructure...
In this paper, we show that for a single crystal sample, the Auger signal intensity depends on the atomic density of the crystalline plane exposed to the analysis. The theoretical approach, based on the Gallon and on the Seah models, is well confirmed by experimental study carried out during the growth of epitaxial gold films on palladium substrates.
Porous silicon (PSi) samples prepared with different electrochemical procedures and experimental parameters have been studied using AES, EELS, Raman spectroscopy and cathodoluminescence. AES and EELS of anodic oxidized PSi samples indicate the formation of SiO 2 , with a band gap of 9 ± 0.5 e V as measured in the loss spectra from the threshold for interband transitions. Oxygen is not detected...
The theoretical approach, based on solving the kinetic equation in the transport approximation, to describe photoemission, has been verified by comparison with Monte Carlo calculations. The analytical expression for the photoelectron distribution with respect to both azimuthal and polar angles has been derived. The angular spectrum of signal photoelectrons has been found to consist of three terms...
The charging of small metallic clusters forming discontinuous gold and gallium films, condensed in vacuum onto an insulating substrate (sapphire), was experimentally studied by the method of ultraviolet photoelectron spectroscopy (UPS) for a photon energy of 5.4 eV. It seems that the charging is due to electron emission as well as to electron transfer from metal islands to the empty electron states...
The influence of surface treatment on the surface properties of Cd 0 . 9 9 Mn 0 . 0 1 Te gallium doped was studied. Using surface photovoltage spectroscopy (SPS) we have investigated three types of the monocrystal surfaces: polished with 'Gamal', etched in 5% Br 2 /methanol and etched in KOH/H 2 O. Changes in the electronic structure of Cd ...
Energy spectra of ions emitted from a cold Au surface covered by a thin film of condensed xenon in the range of small scattering angles (including the case of specular reflection) were measured. If the concentration of particles in adsorbed film and its thickness are relatively small, new scattering effects such as a splitting and shifting of 'single scattering peaks', are observed. These effects...
Two Green function techniques (the direct matching formalism and the interface response theory) are used to investigate the electronic structure of a semi-infinite GaAs/Ga 1 - x Al x As superlattice being in contact with a Ga 1 - y Al y As substrate. The effect of the superlattice termination on the formation of a surface state as well as on the density-of-states...
The adsorption of boron onto the Si(001) 2 1 surface is studied at 0.5 monolayer (ML) coverage using the linear combination of atomic orbitals (LCAO) pseudopotential Hartree-Fock method for periodic systems embodied in the CRYSTAL program. Four stable structures are determined within a range of 0.13 Hartree/(2 2 surface unit cell). The minimum energy configuration is an ad-dimer on-top configuration...
The solid phase reaction of yttrium thin film and silicon substrate was investigated in situ with help of RHEED technique. For the first time, we have measured directly yttrium silicide formation temperature which can be as low as 120°C for a thin (60 ) metal layer deposited on a Si(111) substrate. For this purpose, we developed a new experimental technique. A study of the growth of thin (10-150...
Hydrogen is found to influence the porous Si/PSi system. H atoms cannot be detected by AES or XPS, but profound effects have been observed on PSi using the elastic peak electron spectroscopy (EPES) in the 50-100 eV range after HF treatment of PSi samples. Limited numbers of low energy cross sections are available in the literature. The data of Joy et al are confined to 20 and 50 eV. The differential...
Ab initio calculations at the SCF level were performed in order to determine the electronic structure of copper phthalocyanine (CuPc) and its changes under interaction with the O 2 molecule. The calculated energy levels of CuPc appeared to be in good accordance with other available theoretical data. Determining the electronic structure of the CuPc-O 2 system allowed explanation of...
Inelastic low energy electron diffraction (ILEED) effects have been applied to investigate the initial stages of oxidation on a (001) oriented single tungsten crystal. The electron energy loss spectra (EELS) have been measured as a function of the primary electron energy, E p . The energy was kept within the range: 45 eV < E p < 100 eV. To show the diffraction effect after loss...
The paper deals with porous Si(PSi) samples, prepared with different parameters (substrate, current density, solution, etc.) of anodization and anodic oxidation. The porosity of samples varied between 36 and 78%, their thickness was 1-5 μm. The samples were studied in six laboratories using complementary methods. The spectra of elastic reflection coefficients r e (E p ) are characteristic...
Fractal-like structures have been observed in discontinuous Cu films evaporated onto quartz substrates in vacuo (10 - 8 torr). The microstructures of the films were examined with an electron microscope using a carbon replica. On the basis of the micrographs, the coverage coefficients and the distributions of the island sizes and gap sizes were determined for the Cu films with the coverage...
The understanding of the electronic structure of disordered alloys and bimetallic systems is not yet as advanced as that of ordered crystals. Spectroscopic optical conductivity measurements provide the most direct method for determining the electronic properties of the disordered systems and impurity states. In this paper we present preliminary studies of changes in the electronic structure of host...
Dynamic susceptibility and spin waves are investigated within the framework of the multiband model. Two acoustic modes with amplitudes strongly enhanced at the surface are found. The dispersion relation is calculated The results show that an influence of sp-d hybridization effect on spin-wave energies becomes stronger with an increase in a number of atomic layers.
In this work, results of ion desorption energy (Qi) measurements performed for alkali metals on W. Ta and Re are presented. The dependences of Qi plotted versus the ionic radius of the alkalis are well approximated using the interaction potentials of an ion and a flat metal surface. The fitting parameters which characterize the interaction potentials are given.
We present the calculations of vibrational states on the Al(110), Cu(110), Ag(110) and Pd(110) surfaces. The surface phonon frequencies and polarizations are calculated using embedded atoms potentials. For all surfaces of interest a surface state at the Γ point, characterized by shear vertical displacements of atoms of the two upper layers is obtained. It is in contradiction to earlier calculations...