Vol 51, No 13 (2017)

The Stoneley problem is analytically solved for the piezoheterolayers of cubic symmetry crystals for the first time. New types of acoustoelectric waves, in contrast to classical Stoneley waves, are plane-polarized in the direction orthogonal to the sagittal plane. The wave electric field in each layer is elliptically polarized in the sagittal plane. The use of new types of acoustoelectric waves will make it possible to significantly extend the capability of modern acoustoelectronic devices and is directly associated with the transition from acoustoelectronics to acoustonanoelectronics corresponding to the nanometer wavelength range with a carrier frequency of the order of hundreds of gigahertz.

The technological process of the production of silicon nanoparticles from silicon monoxide and methods of the deposition of nanosilicon coatings onto solar cells are developed. The process makes it possible to control the particle dimensions in the range from 2 to 10 nm. The effect of such nanosilicon coatings on the efficiency of solar cells is studied. It is shown that nanosilicon films possess good antireflection and passivation properties and can be successfully used in the technology of the production of solar cells.

The development of new nanostructured materials based on YBa₂Cu₃O_7–δ, BiFeO₃, and Fe₃O₄ compounds is considered. The structure, morphology, and properties of these materials are studied. The possibilities of fabricating YBa₂Cu₃O_7–δ ceramics with given densities from nanopowders in a single stage by an energy efficient method and growing superconducting films of the same composition on a silicon substrate (on a SiO₂ layer) are demonstrated. The technique for fabricating BiFeO₃ nanopowder, making it possible to obtain nanostructured ceramics without additional accompanied phases commonly forming during BiFeO₃ synthesis is developed. Two methods of the single-stage synthesis of Fe₃O₄ nanopowder are presented: burning of nitrate-organic precursors and the electrochemical three-electrode method in which one of the electrodes, i.e., an anode containing scrap iron and slurry, is used as an expendable material.

Experimental results of the formation of a periodic submicron structure on the surface of polycrystalline nickel (Ni) under laser irradiation in air and in a liquid medium (distilled water) are presented. The geometry of the formed surface structures is determined by electron-microscopy methods. When irradiated in air, the structure is formed above the base surface of the sample, and when irradiated in the liquid, it is formed below the base surface. The dimensions of the pure Ni nanoparticles formed during laser ablation of the nickel sample in the liquid were determined.

The results of a study of film composites based on polyvinylidene fluoride with carbon nanotubes (CNTs) by dielectric relaxation spectroscopy are presented. For composite samples containing more than 0.5 wt % of nanotubes, nonlinear current–voltage characteristics are obtained. The concentration dependences of the electrical conductivity of the composites are examined and the percolation threshold for the samples under study is determined. It is shown that an insignificant increase in the electrical conductivity of the composites is observed even upon filling with 0.2 wt % of CNTs, whereas the electrical conductivity becomes three orders of magnitude higher upon the introduction of 1 wt% of CNTs and is seven orders of magnitude higher at more than 3 wt %, compared with the unfilled polymer. This confirms that CNTs are promising for the development of electrically conducting composites and film materials on the basis of polyvinylidene fluoride.

The characteristics of the dynamic range of a multichannel photocell and the signal-to-noise ratio for read-out photosignals from n and p regions of the photocell are investigated. It is established that the values of the photosensitivities depend both on the chosen design parameters of the photocell and on the highest possible control voltages. It is shown that the read-out photosignal of the multichannel photodiode structure is proportional to the luminous flux.

The fabrication processes for narrow-spectrum photosensitive structures based on J-aggregates of cyanine dyes are studied. Two technological approaches are proposed: the electrokinetic deposition of single J-aggregates in the planar electrode configuration and the fabrication of multilayer structures with a sensitive layer of cyanine dye J-aggregates and a transparent electrode made of a conductive carbon nanotube network on a flexible polyethylene naphthalate substrate.

The formation of nanostructure arrays on the surface of nanocrystalline tin sulfide (SnS) films during inductively coupled argon plasma treatment is investigated. The parameters of the nanostructures are studied by electron microscopy and energy-dispersive X-ray microanalysis and the main regularities of nanostructure growth are established. It is shown that the SnS nanostructure growth during plasma treatment is complex and involves the vapor–liquid–solid mechanism with self-assembled tin seeds.

A new contactless nondestructive technique for determining the free carrier density in single-crystal samples of Cd_xHg_1–xTe solid solutions and multilayer epitaxial heterostructures based on them from farinfrared reflection spectra is proposed. The characteristic point and corresponding wavenumber in the room-temperature spectral dependence of the reflectance are determined. The heavy hole density is established using calculated calibration curves. It is shown that in constructing the calibration curves, it is necessary to take into account the interaction of plasma oscillations with longitudinal optical phonons.