Search

Structural properties of PbSe, PbS and PbS0.5Se0.5 thin films and mechanisms of combinational scattering of light from phonons were studied by X-ray diffraction and Raman spectroscopy methods. The results of X-ray diffraction show that the crystallite sizes found in the thin layers of the studied substances are in the order of nanometers and vary in the interval d~10.7 ÷ 30.8 nm. It was determined that the scattering bands of the PbSe0.5S0.5 sample with large nanoparticle sizes shift to the region of large wave numbers compared to the scattering bands observed in the region of low wave numbers. [ABSTRACT FROM AUTHOR]

The local structure of film samples of the chalcogenide glassy semiconductors Se95As5 and Se95As5(EuF3)x (x = 0.01–1 at %) are studied by X-ray diffraction and Raman scattering. The "quasiperiod" of the structure, the correlation length, the structural elements, and the chemical bonds, which form the amorphous matrix of the investigated materials, are determined. The obtained results are interpreted within the framework of the Elliott void–cluster model taking into account the chemical activity of europium ions. [ABSTRACT FROM AUTHOR]

The study is dedicated to the investigation of thermo-physical characteristics of Se95Te5 chalcogenide glassy semiconductor during its glass formation and crystallization processes, employing various scanning rates of 5, 10, 15 and 20 K/min in non-isothermal modes through DSC measurement. Analysis of the structural relaxation kinetics involves the Kissinger's, Augis and Bennett's, as well as Matusita's approaches. Experimental data yield contains the determination of crucial parameters such as glass transition (Tg), crystallization (Tc), and melting temperatures alongside factors like reduced temperature of glass transition (Trg), Hruby's parameter (Kgl), fragility index (Fi), Avrami exponents (n, m), glass transition ((140.24 kJ/mol) and crystallization (Ec = 95.11 kJ/mol) energies, respectively. The results confirm that Se95Te5 chalcogenide system as an efficient glass former. Matusita's method reveals that the crystallization mechanism (n = 2.51, m = 1.9) corresponds to volumetric nucleation with two-dimensional growth. [ABSTRACT FROM AUTHOR]

The results of a comparative analysis of optical properties taking into account the structural features and morphology of the surface of films based on Se95As5 (EuF3)x (x = 0.001-1 at.%) obtained by thermal evaporation on cold glass substrates in a vacuum of 10-6 mm Torr. Habe been presented. The effect of europium on the optical properties and morphology of the surface of Se95As5 films were studied. Taking into account the structural features of Se95As5, as well as the manifestation in them of EuF3 in the form of ions, the observed features of the concentration dependence of the optical constants on the EuF3, as well as the relief images observed by the AFM method, are explained. The width of the forbidden band of the material under study was determined using the Tautz model, and for all samples the band gap widths were determined whose values varied within 1.91÷ 1.95 eV. As can be seen, there is no significant change in the width of the forbidden band when an impurity is introduced. [ABSTRACT FROM AUTHOR]

It was established that influence of the EuF3 impurity on a luminescence and photoconductivity spectra of the Se-As chalcogenide glass-like semiconductor system have been explained within of the charged intrinsic D- and D+ defects model. By investigation of the luminescence spectra and the photocurrent spectral distribution of the Se95As5 and Se95As5 (EuF3) x (x = 0.01-1 at. %) film samples have been shown that the EuF3 impurity changes the concentration of charged states nonmonotonically. It was shown that the participation of EuF3 in Se95As5 leads to an increase in the transparency of the material as a result of a shift in the absorption edge toward shorter wavelengths and photo enlightenment of the material was observed and large number of the impurity result in radiative recombination. The positions of Ed and Ea recombination levels with respect to the edge of the valence band, also the activation energy of dark conductivity and some parameters of the charged defects model, the effective correlation energy Ueff (0.6 eV), the polaron relaxation energy W + (0.4 eV), W- (0.45 eV) have been estimated. [ABSTRACT FROM AUTHOR]

In this work have been investigated the structural features of As-Se-S and As-Se-Te systems and their alloying with Sm on the nanometer scale using small-angle neutron scattering and Raman spectroscopy. These materials have two-phase porous structure, i.e. materials outfit with solid particles and includes free volumes. The parameters of fractal structure have been determined, in particular, the upper and lower boundaries of selfsimilarity and size of particles forming fractal clusters. The observed features of Raman scattering are associated with relaxation and excess density of states of acoustic vibrations in irregularities. Such irregularity areas are associated with the presence of nano-size inhomogeneities. [ABSTRACT FROM AUTHOR]

The crystallization dynamics of Bi2Te3-Bi2Se3 polycrystalline films annealed at 200–230°C has been investigated. The formation of ordered blocks 70—150 nm in size, depending on the annealing time and temperature, is observed. [ABSTRACT FROM AUTHOR]

By X-ray diffraction method the structure of chalcogenide glass-like semiconductors As2Se3, As40Se30S30, As40Se30Te30, As-Se-S and As-Se-Te has been investigated. Data analysis obtained from the first sharp diffraction peak shows that the degree of disorder for glasses of nonstoichiometric composition is higher than for stoichiometric one. It is also shown that tellurium containing samples are more disorder. [ABSTRACT FROM AUTHOR]