[en] A description is given of a precision method for measuring the velocity of propagation of ultrasonic waves in metals and alloys. Experimental data are presented on the velocity of propagation of unltrasonic waves in specimens of artificial quartz, Armco-iron, various steels, titanium-based alloy. The error in the determination of the absolute value of the propagation velocity of longitudinal waves approximated 0.01%, and of the relative values, 0.003%

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[en] Radiation resistance of anionites based on formolites, obtained out of oil asphaltites by means of copolycondensation with toluene and formaldehyde in the presence of sulfuric acid, is studied. Under the action of γ-radiation on anionites desamination is the prevailing process, degradation occurring in a lesser degree. The anionites synthesized withstand γ-radiation effect more effectively than the known polystyrene and asphaltite ones which contain similar ionogenous groups

[en] Possibility of formation and further development of composition fluctuations at layer-by-layer growth of epitaxial film with regard to elastic interaction, is studied. Kinetic instability under which the long-range elastic stresses promote occurrence and further intensification of the composition space modulation, is shown to occur at layer-by-layer growth of solid solution. T_c^k temperature of kinetic instability that is higher, than T_c⁰ thermodynamic critical temperature of T spinodal decomposition calculated disregarding the elastic energy, is determined analytically. Evolution of solid solution profile during epitaxial layer growth is determined. Exponential intensification of composition heterogeneities in proportion to the increase of epitaxial layer thickness, is shown to occur at T < T_C^k. 46 refs.; 2 figs.; 1 tab

[en] Theoretical and experimental studies have been conducted to consider the influence of unidimensional disorder on exciton states in A₂B₆ binary compounds and solid solutions on their base (Zn_xCd_1-xS₂). Sphalerite-wurtzite structural phase transformation in the systems considered is shown to proceed through intermediate structures containing polytypes and stacking faults. A technique has been developed for evaluation of stacking faults through exciton reflection spectra. 11 refs., 4 figs., 4 tabs

[en] The impact of growth temperature on density, lateral size and height of InAs-GaAs quantum dots (QD) is studies by transmission electron microscopy. With the increase in temperature from 450 to 520 deg C, the density of QD decreases while their lateral size increases and the height decreases. An observation blue shift of the photoluminescence line shows that QD volume decreases as the temperature increases. These experimental results confirm thermodynamic models of QD formation. The influence of the decrease in the substrate temperature immediately after QD formation on parameters of QD arrays is also investigated

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No abstract available

[en] We present a linear stability analysis of an hexagonal array of coherently strained islands against the exchange of material between islands. Surprisingly, ultra-dense arrays are found to be metastable due to the short-range stabilizing effect of elastic interactions which overcome the destabilizing contribution of surface energy. Mean-field simulations are used to investigate the ripening kinetics of local volume defects in arrays which are found to equilibrate through island volume oscillations. Simulations of global perturbations directly verify the existence of the metastable regime and confirm the nature of the most unstable mode as derived from the stability analysis for sub-critical island coverage

[en] Strain-driven decomposition of an alloy layer is investigated as a means to control the structural and electronic properties of self-organized quantum dots. Coherent InASGaAs islands overgrown with an InGa(Al)As alloy layer serve as a model system. Cross-section and plan-view transmission electron microscopy as well as photoluminescence (PL) studies consistently indicate an increase in height and width of the island with increasing indium content and/or thickness of the alloy layer. The increasing island size is attributed to the phase separation of the alloy layer driven by the surface strain introduced by the initial InAs islands. The decomposition is enhanced by the addition of aluminum to the alloy layer. The ground-state transition energy in such quantum dots is significantly (up to 200 meV) redshifted compared to the original InASGaAs quantum dots, allowing to reach the 1.3 μm spectral region maintaining the high PL efficiency and the low defect density typical for Stranski-Krastanow growth. The possibility of degradation less stacking of such quantum dot layers enables injection lasing on the ground-state transition with a differential efficiency of 57% and a continuous-wave output power of 2.7 W