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Semiconductor nanowires (NWs) offer multiple advantages for designing novel optoelectronic devices, such as small footprint, high quantum efficiency, high nonlinear susceptibility. Gallium phosphide (GaP) is one of the attractive materials owing to its low optical absorption and high nonlinear susceptibility. However NWs should be transferred to planar substrates for optical studies, which do not allow efficient signal outcoupling. We demonstrate efficient second harmonic generation in individual GaP nanowires trapped using optical tweezers. Such vertically arranged configuration of NW allows to both efficiently generate second harmonic and to probe linear optical response using broadband light source. Such experiment allows to examine interplay between harmonic generation efficiency and NW dimensions.

Heterostructured AlGaAs/Ge/AlGaAs core-multishell nanowires having hexagonal crystal structure were synthesized by molecular beam epitaxy. Formation of 2-3 nm Ge quantum well structure was demonstrated. Raman characterization revealed a 200 cm−1peak corresponded to hexagonal phases of germanium.

Planar photonic structures, such as gratings and metasurfaces, are routinely used for beam steering, waveguide coupling, and light localization. However, conventional fabrication techniques that involve lithography are demanding in terms of time and cost. Much cheaper and simpler methods for surface patterning and formation of periodic surface structures are enabled by direct laser processing. Here, we demonstrate low-cost rapid fabrication of high-quality phase gratings based on the formation of laser induced periodic surface structures (LIPSS, or ripples) in Ge2Sb2Te5 (GST) thin films. Due to unique phase change properties of GST, the structures demonstrate strong modulation of refractive index with period controlled by the wavelength of laser irradiation. We study the formation of phase change LIPSS in a broad range of excitation wavelengths and observe transition between regimes with different orientations of generated ripples with respect to laser polarization.

Since emerging Metal Halide Perovskites were attracting elevated attention from scientific and industrial communities. Although, we still yet to see commercial products based on perovskite materials a significant body of work has been already done. Here we present our own method of Metal Halide Perovskites integration into possible industrial applications. Our way of Perovskite Quantum Dots encapsulation in polymer fibers provides exceptional water and ambient stability as well as optimal photoluminescence.

In this letter, we report the growth of the self-catalyzed GaP nanowires with a high concentration of wurtzite phase by molecular beam epitaxy. Formation of rotational twins and wurtzite polymorph in vertical nanowires was observed by the developed a complex approach based on the transmission electron microscopy and X-ray diffraction method. Microstructural analysis performed by high resolution transmission electron microscopy and micro-Raman spectroscopy gives us insights on the nanowire formation mechanism and vibrational properties of nanowires with mixed crystal phase. We obtained wurtzite polytype segments with thicknesses lying in the range from several tens up to 500 nm. The results of the work open new perspectives for high phase purity phosphide NWs synthesis and its fast investigation with XRD technique using a laboratory X-Ray source.

The study of nanostructure, thermal and relaxation properties (by HAADF-STEM, EDXS, DMA and DSC), combined with the calculations of interparticle distances and interfacial areas, has been performed for a series of the hybrid Cyanate Ester Resin (CER)/Si02 polymer composites with 0.01 to 10 wt.% Si02 units introduced via a sol-gel process. The absence of clusterization, arising only subnanometric Si02 nodes and their quasi-regular distribution within the amorphous matrix, with the shortest distances between nodes, provided their exceptional positive impact on the matrix properties at ultra-low Si02 contents of 0.03-0.1 wt.%. The superiority of these subnanocomposites over the nanocomposites was determined by the role of constrained interfacial dynamics over the whole matrix.

A series of the hybrid Bisphenol A based Phthalonitrile (BAPhN)/amino-Montmorillonite (amino-MMT) polymer nanocomposites with the complex heterocyclic matrix network and 0.03–5.0 wt.% amino-MMT were synthesized and studied. Their molecular structure, nanostructure, molecular dynamics, thermal, relaxation and elastic properties were characterized using TEM, EDXS, DMA, TGA, FTIR and Far-IR spectroscopies including also the experiments in flowing nitrogen medium. Depending on nanofiller content, different extents of MMT stacks exfoliation, from a single nanolayer to stacks with tens nanolayers-thickness, were registered in these nanocomposites. The exceptional combining of high temperature properties was revealed for these nanocomposites.

Periodic photonic nano- and microstructures are routinely used for light manipulation at the nanoscale. However, their fabrication process is demanding in terms of time, cost and facilities. Here we demonstrate a rapid laser-assisted method for fabrication of gratings in Ge2Sb2Te5 (GST) thin films, based on the formation of laser induced periodic surface structures (LIPSS). LIPSS formation mechanisms dependent on the wavelength of the operating laser, lead to high flexibility of the process, producing gratings with tunable period and orientation with respect to the initial laser polarization. The phase-change properties of GST, on the other hand, allows to fabricate phase gratings with strong modulation of refractive index, which are rewritable in nature.

This paper presents the results of experiments carried out to reveal the influence of the initial parameters of the thermite mixture Al–CuO on the signs of a chemical reaction between its components. Initial parameters were the characteristics of the starting components, preparation conditions and characteristics of the mixture and samples, experimental schemes, methods of initiation. The most important parameter was the preliminary mechanical activation of mixture. The prepared mixture with controlled porosity was placed in experimental assemblies and a chemical reaction was initiated. Values and tendencies of the brightness temperature and the propagation rate of reaction area were determined for different initial parameters of mixture and initiation conditions. The reaction in the volume of the experimental assembly goes into flare combustion in open space. Values of brightness temperature at the stage of flare formation have a stochastic character, determined by the random distribution of reaction sites in the initial volume of the components. A high-speed camera, a pyrometer, photoelectronic and electrocontact sensors were used as diagnostic tools. The final goal of the study is to optimize parameters of mechanical activation of mixture for its effective applying in various conditions.

The technique for determination of strain and elemental composition distribution across the graded layer in heterostructures by means of selected area electron diffraction in transmission electron microscope (TEM) is proposed. The approach accounts for the modification in the residual elastic strain due to sample thinning during TEM specimen preparation. The technique is approved using In0,7Ga0,3As/InxAl1-xAs/GaAs(001) and Al0,75Ga0,25N/AlN/Al2O3 heterostructures, and the results are in a good agreement with those obtained by alternative ways.

In this study we related structural properties of GaN grown on ceramic substrate and studied with transmission electron microscopy with the results of photo-and cathodoluminescence investigations. We found that stacking faults in the basal plane were responsible for both strong room temperature visible emission and exciton-related ultraviolet luminescence at cryogenic temperature.

In this work we present a facile method for the synthesis of the carboxylated graphene derivate. The resulting material contains up to 10.9 at.% of carboxyl groups and with negligible content of other oxygen-containing groups. Moreover, formation of large round-shaped nanoscale holes is observed due to the applied synthesis process. The synthesized graphene derivative is of high interest for the sensing applications due to combination of its conductive nature and chemical reactivity provided by the attached carboxyl groups.

Formation and propagation of the antiphase domains in dilute nitride GaPN/GaP epitaxial heterostructures grown on Si (001) by plasma assisted molecular beam epitaxy (PA-MBE) on silicon is studied. Role of the layer composition, substrate orientation and growth conditions are discussed. Composition of the dilute nitride film was studied by X-ray diffraction (XRD) while the effect of the antiphase disorder in GaP buffer layer on GaPN epilayer structural properties was studied by transmission electron (TEM) and scanning electron microscopy (SEM). Controllable transition between antiphase disordered and monodomain film depending on the concentration of incorporated nitrogen is demonstrated – transition to the monodomain film occurs in dilute nitride GaPN layers starting low with 0.4% of incorporated nitrogen. Control of the antiphase disorder allows to tune mean film polarity and second order nonlinear optical response of III-phosphide heterostructures.

The paper reports on molecular beam epitaxy of ZnSe/InSe/ZnSe quantum well (QW) heterostructures grown on GaAs(001) substrates as well as studies of their structural properties. The structures were characterized by reflection high energy electron diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy techniques. The evolution of surface morphology of QW heterostructures as a function of the InSe thickness has been studied. The quasi van der Waals growth of ZnSe on the InSe(0001) surface has been demonstrated, with the ZnSe(111) plane being oriented parallel to the (0001) plane of InSe because of a small lattice mismatch between InSe and ZnSe(111).

In the article, the study of the morphology, crystal structure and chemical composition of InxGa1-xN nanostructures is presented. Scanning electron microscopy measurements show that the sample has a structure consisting of nanotubes, on top of which an array of nanocrystals (so-called “nanoflowers”) is formed. The results of transmission electron microscopy show that the nanotubes have a wurtzite crystal structure, whereas the “nanoflowers” exhibit both wurtzite and zinc blende one. The indium composition in wurtzite and zinc blende segments is about 20 % and 10 %, respectively.

The optical absorption spectra and structural properties of samples series consisting of AZO oxide films with an intermediate layer of silver nanoparticles with different sol compounds were investigated. TEM analysis of the obtained coatings showed that the nanoparticles in the AZO film form an ordered structure, and the distance between them depends on the sol composition and the film annealing temperature. Optical measurements showed that a position of the nanoparticle plasmon peak in AZO also depends on them.

The combination of X-ray tilt-azimuth figure, reciprocal space map and transmission electron microscopy in selected area electron diffraction mode was applied to analyse the tilt of the MBE-grown 1.2-μm thick convex-graded InxAl1-xAs (x=0.05-0.80) metamorphic buffer layer on singular GaAs (001) substrate. The combination of the techniques is demonstrated to enable the determination of the tilt angle as well as the tilt direction together with monitoring of the tilt development along the growth direction. For the studied metamorphic buffer layer as an example, the tilt direction was deduced to be 20° off the (110) GaAs substrate crystallographic plane. The tilt angle of (002) buffer layer planes was observed to rapidly rise to 0.6° near the layer-substrate interface and then to slowly increase to 1.4° with the approach toward the surface.

An anodic oxidation of GaAs substrates in a non-self-sustained low-current dc Townsend discharge is investigated. The process is carried out at the room temperature in a three-electrode microreactor filled by 98%Ar + 2%O2 gas mixture. Investigation of the oxidation kinetics indicates that the formed oxide is characterized by a high resistivity, ρ ∼ 1011 Ω·cm. It is demonstrated the application of the method for formation of oxide films with dimensions of tens of microns, which thickness is on the nanometer scale. Examination of the “GaAs substrate - oxide layer” interface using the high resolution transmission electron microscopy has revealed that the oxide is characterized by the amorphous structure.

The propagation of vortex laser beams in the near diffraction (at a distance in the order of the wavelength) can be described by means of an expansion in plane waves, which after considering vortices reduces to an vortex propagation operator involving Fourier-Hankel transforms. The eigenfunctions of the operator, when eigenvalues are close to one, determine the characteristics of the signals (information) transmitted lossless (without distortion). The beam propagation distance, vortex order and the region of spatial frequency limitation are parameters of the operator and they essentially change the set of eigenvalues and functions. We calculate the vortex eigenfunctions of the finite propagation operator in the near diffraction zone and investigate their qualitative and quantitative characteristics depending on the propagation distance, the order of vortex and the constraints imposed in the object and spectral domains.

In TAIGA Observatory (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) we are commissioning the first Imaging Atmospheric Cherenkov Telescope (IACT). The telescope has an alt-azimuth mount and 17-bit shaft encoder for each axis, stepper motors are used for axis control. For the pointing calibration of the telescope a CCD-camera is installed on the dish of the telescope and its position allows to capture simultaneously both the Cherenkov camera with LEDs and the sky with observed source. Since October 2017, the telescope has been operating in tracking mode. In this work the TAIGAIACT telescope pointing calibration approach and first results of the tracking operations are described.