The atomic structure of zinc sulfide films obtained by thermal evaporation in ultrahigh vacuum at condensation temperatures of −100°C, −50°C, and 0°C was investigated. Structural states were assessed by means of X-ray diffraction and atomic force microscopy. Fourier transform was used to study the local atomic environment and acquire the structural information (interatomic distances and coordination numbers) by zinc K edge EXAFS spectroscopy.

The local atomic structure and surface morphology of thin semiconductor films of Ge have been studied via extended X-ray absorption fine structure spectroscopy and atomic force microscopy. The films have been obtained by thermal evaporation of a material in an ultrahigh vacuum at different substrate temperatures. The films contain both amorphous and nanocrystalline phases. The percentage of the phases depends on the condensation temperature. The classical linear dependence of grain sizes on condensation temperature T is violated at T=100°C.

A novel approach is presented for synthesis of ZnSe nanodot arrays by physical vapor deposition on porous aluminum oxide templates with ordered channels. The structure of nanodots was studied by scanning electron microscopy and EXAFS spectroscopy. Data were obtained for the sizes of nanodots in the array and local atomic structure parameters, i.e., the interatomic distances and coordination numbers, in comparison with the data for the ZnSe film synthesized on a smooth surface of nonporous Al2O3.

The extended energy-loss fine structure (EELFS) spectra for pure nickel samples (M 2,3 EELFS spectra), a NiO stoichiometric film (nickel M 2,3 EELFS and oxygen K EELFS spectra), and an “inhomogeneous” oxide film (Ni-O system) on the surface of nickel have been obtained. The calculations of amplitudes and intensities of electron transitions are performed for the corresponding inner levels of atoms taking into account the multipolarity of the excitation of inner atomic levels by an electron impact. The normalized oscillating components are extracted from EELFS spectra using the results of calculations. Close agreement between experimental results and theoretical data obtained for test Ni samples and NiO films indicate that the theoretical approaches applied to the description of EELFS spectra and the results of calculations are good approximations. Atomic pair correlation functions are obtained from the experimental normalized oscillating components of EELFS spectra with the use of the Tychonoff regularization technique.

The electron energy loss extended fine structure (EELFS) spectra were obtained from the pure nickel surface (M (2,3) EELFS) of a stoichiometric NiO film (NiM (2,3) and OK EELFS spectra) and the "nonhomogeneous" oxide film on the surface of nickel Ni-O (NiM (2,3) and OK EELFS spectra). The amplitudes and intensities of electron transitions for the core levels of atoms were calculated with regard for the multiplicity of electron impact excitation of the corresponding core levels of atoms. The corresponding normalized oscillating terms were isolated using the results of calculations based on the experimental EELFS spectra. Agreement between the experimental and calculated (on Ni and NiO test objects) data showed that the theoretical approaches used and the calculated data for describing the EELFS spectra are good approximations. Using the results of calculations and the parameters of secondary electron elastic scattering (FEEF-8 data) we obtained the atomic pair correlation functions from the experimental normalized oscillating parts of the EELFS spectra by Tikhonov's regularization method.

This paper presents the results of our study of the structural state and local atomic structure of zinc selenide films obtained by thermal evaporation in supervacuum at condensation temperatures of −150°C, 0, and 150°C. Structure-sensitive methods such as X-ray diffraction, atomic force microscopy, and EXAFS spectroscopy were used. The parameters of the local atomic environment (interatomic distances, coordination numbers) of zinc and selenium atoms were obtained by Fourier transformation.

Simple formulas for describing the extended fine structures of spectra of electron energy losses (EELFS) with allowance for the multipolarity of the process of excitation of the inner level of atoms by electron impacts have been derived. The experimental M 2,3 EELFS spectra of nickel and K EELFS spectra of oxygen were obtained from pure samples of nickel and stoichiometric oxide film on the surface of nickel. Good agreement has been obtained between the experimental and calculated results, as well as between the parameters of a local atomic structure obtained from the experimental EELFS spectra and available crystallographic data.

The work presents the theoretical description of formation processes of extended electron energy loss fine structure (EELFS) spectra. Simple analytical formulas are obtained to calculate EELFS spectra. Methods are proposed to compute amplitudes and intensities of electronic transitions of different multipolarity in electron-impact excitation of the inner shell of an atom. The corresponding test calculations are performed. We present experimental M 2,3 EELFS spectra of 3 d -metals obtained from clean surfaces of Fe, Ni, and Cu and ultrathin stoichiometric oxide films of Fe 2 O 3 , NiO, and CuO as well as K EELFS spectra of oxygen from thin stoichiometric oxide films. Techniques are proposed to extract normalized oscillating parts from experimental EELFS data based on the use of calculated intensities of the corresponding electronic transitions. Atomic pair correlation functions are obtained for the objects under study from experimental EELFS data with regard to multipolarity of electron impact excitation of the atomic inner shell. Experimental results correspond well to known crystallographic data (partial interatomic distances, coordination numbers, and Debye-Waller factors).

The local atomic structure of thin surface layers of crystalline quasi-binary Cu(In x Ga1−x )Se2 solid solutions was studied by SIMS and EXAFS techniques. The SIMS method showed that the elemental composition of the sample changes most significantly in thin layers at a depth of 5–10 nm; in deeper layers, the component concentrations correspond to the bulk values. The EXAFS method in the x-ray fluorescence mode showed that the results obtained are in agreement with the assumption that quaternary crystalline quasi-binary Cu(In x Ga1−x )Se2 solid solutions exhibit local disorder while average long-range order is detected from x-ray diffraction data.

The nanoscale semiconductor structures obtained by evaporation in high vacuum at different temperatures show anomalous high photoconductivity. This may be connected with the structure of clusters which can consist of both crystalline and amorphous phases. We propose a method of extracting amorphous and crystalline contributions to the clusters. This method is based on the extraction of corresponding contributions to the extended x-ray absorption fine structure (EXAFS) spectra. The method of EXAFS spectroscopy allows information to be obtained about the local atomic structure of materials in different states, including gases and liquids. The macro-structure of films was examined by different methods, i.e. x-ray diffraction, transmission electron microscopy (TEM), and atomic force microscopy (AFM). We obtained the volume portion of the amorphous phase to the nanosized particles of Ge as about 70% and for GaAs about 50%. Copyright (C) 2004 John Wiley Sons, Ltd.

Secondary electron spectra of Fe, Ni, Cu pure surfaces and corresponding oscillating signals were obtained. The atomic pair correlation function was estimated by solving the inverse problem using the Tikhonov regularization method. The results obtained and the application of the secondary electron fine structure method for local atomic structure analysis are discussed.

Results of investigation of Ge films obtained by the method of thermal evaporation in vacuum at different substrate temperatures are presented. The structure and temperature dependence of the resistivity of obtained films are studied by different methods.

The changes in the nearest - neighbour surroundings of carbon atoms in the cementite Fe3C lattice due to the heat treatment are analysed by the Extended Energy Loss Fine Structure (EELFS) method. To study the local atomic structure of the carbon steel U15 after different heat treatment regimes the electron energy loss spectra above the C K edge and Fe L2,3 edge were measured. The measured experimental EELFS spectra were treated by the standard for the Extended X - ray Absorption Fine Structure method procedure using Fourier transformation to obtain the parameters of the nearest - neighbour atomic surroundings. Qualitatively the assumption was made that the number of the iron atoms in the carbon atom nearest - neighbour surroundings changes due to the heat treatment, the evidence of which was the change in the ratio of the first two feature intensities of the atomic radial distribution function. This assumption is consistent well with the previous Mössbauer data.

Conditions were considered for producing GaAs nanocrystalline films by a thermal method on the basis of a UVN-71-P3 modernized vacuum setup using three evaporator types. The extended X-ray absorption fine structure (EXAFS) method was applied to study the local atomic structure of the samples produced. (C) 2001 MAIK "Nauka/Interperiodica".

A new method of studying local structure in disordered binary systems by combined EXAFS is proposed. This consists of determining partial interatomic distances by solution of the system of integral equations describing two EXAFS spectra. This information is used as input data for the determination of partial coordination numbers. The problem in this case is reduced to the solution of the well-conditioned system of linear algebraic equations. We apply this method to obtain local structure information in Ge–Si solid-state solutions.

The extended energy-loss fine structure (EELFS) spectroscopy was used to analyze the response of the nearest neighborhood of carbon atoms in the lattice of cementite Fe3C to heat treatment. For the study of the local atomic structure of the U15 steel after different heat treatments, the electron energy loss spectra were obtained beyond the carbon K edge. The experimental EELFS spectra were treated by the standard technique employed for processing EXAFS (extended X-ray absorption fine structure) spectra, i.e., using the Fourier transformation for determining the parameters of the nearest atomic neighborhood. A qualitative conclusion was made that heat treatment affects the number of iron atoms in the nearest neighborhood of carbon atoms in cementite. This conclusion is based on the changes in the ratio between the intensities of two first maxima of the radial atom distribution functions and is consistent with Mossbauer data.