A. N. Deev

EXAFS SPECTROSCOPY STUDY OF THE ATOMIC STRUCTURE OF ZnS NANOCOMPOSITE THIN FILMS

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.

Determination of atomic pair correlation functions for nickel oxide films via extended energy-loss fine structure spectroscopy

The extended energy-loss fine structure (EELFS) spectra for pure nickel samples (M2,3 EELFS spectra), a NiO stoichiometric film (nickel M2,3 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.

Study of thin Ge films with amorphous and nanocrystalline phases via the techniques of EXAFS spectroscopy and AFM

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.

Local atomic structure of Cu(In x Ga1−x )Se2 (x = 0.25, 0.5, and 0.75) systems for solar cells

The local atomic structure of thin surface layers of crystalline quasi-binary Cu(InxGa1−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(InxGa1−x)Se2 solid solutions exhibit local disorder while average long-range order is detected from x-ray diffraction data.