Table of contents

Dear Colleagues,

3rd International School and Conference "Saint Petersburg OPEN 2016" on Optoelectronics, Photonics, Engineering and Nanostructures was held on March 28 - 30, 2016 at St. Petersburg Academic University of the Russian Academy of Sciences. The School and Conference included a series of invited talks given by leading professors with the aim of introducing young scientists to the actual problems and major advances in modern physics and technology. The keynote speakers were

Mircea Guina(Tampere University of Technology, Finland)

Evgeny I. Terukov(Ioffe Institute RAS, Russia)

Victor M. Ustinov(Ioffe Institute RAS, Russia)

Peter G. Kazansky(University of Southampton, UK)

Alexander O. Golubok(ITMO University, Russia)

Georgy E. Cirlin(St Petersburg Academic University RAS, Russia)

Levon V. Asryan(Virginia Polytechnic Institute and State University, USA)

Andrey A. Lipovskii(Peter the Great St.Petersburg Polytechnic University, Russia)

During the poster session all undergraduate and graduate students attending the conference presented their works. A large number of participants with more than 280 student attendees from all over the world allowed the Conference to provide a fertile ground for the fruitful discussions between the young scientists as well as to become a perfect platform for the valuable discussions between student authors and highly experienced scientists. The best student papers, which were selected by the Program Committee and by the invited speakers based on the theses and their poster presentation, were awarded with diplomas of the conference - see the photos.

This year "Saint Petersburg OPEN 2016" is organized by St. Petersburg Academic University in cooperation with Peter the Great St. Petersburg Polytechnic University. The School and Conference is supported by the Russian Foundation for Basic Research(Project N 16-32-10060), Russian Science Foundation, SPIE (The International Society for Optics and Photonics) and OSA (The Optical Society). It is a continuation of the annual schools and seminars for youth on topical problems of physics and technology that is organized by the Academic University since 2009.

We invite all students and young scientists to attend "Saint Petersburg OPEN" in 2017!

Please find details at http://spbopen.spbau.com/

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Grain size effect on microhardness and Young modulus of polysilicon layers was obtained by nanoindentation experiments: 14.1-16.3 GPa and 240-300 GPa, respectively, for the particle-diameter of 117-430 nm. The range of grain size correlated to mechanical properties exceed theoretical values was defined. The doping effect was considered. The grain size range of PECVD polysilicon with aspects of hardening and suitable conductivity is presented with the objective to formation of micro- and nanomechanical devices.

Electrical properties of single GaN nanowires grown by means of molecular beam epitaxy with N-plasma source were studied. Ohmic contacts connected to single n-type GaN wires were produced by the combination of electron beam lithography, metal vacuum evaporation and rapid thermal annealing technique. The optimal annealing temperature to produce ohmic contacts implemented in the form of Ti/Al/Ti/Au stack has been determined. By means of 2-terminal measurement wiring diagram the conductivity of single NW has been obtained for NWs with different growth parameters. The method of MESFET measurement circuit layout of single GaN nanowires (NWs) has been developed. In accordance with performed numerical calculation, free carriers' concentration and mobility of single NWs could be independently estimated using MESFET structure.

Fabrication and study of specialized single nanowhisker probes are performed for high-precision investigation of elements such as nanospheres and nanorods using the atomic force microscopy. It was found that single nanowhisker probe significantly increases the resolution and contrast of images obtained in the semi-contact mode. Furthermore, the roughness analysis and adhesion forces are investigated in contact mode to comprehensively characterize properties of nanospherical and nanorod electronic structures.

It is well known that the physical properties of thin films depend on their thickness. For a description of such dependences, it is proposed to use a classical model taking into account the presence of film interfaces. A dielectric ball near the half-space was chosen to adopt the approach. The dependence of the effective permittivity of the ball on geometrical and physical parameters of the system is analyzed. It is demonstrated that the dielectric constant of a film can be presented as a sum of the constant of a bulk material and the interface term.

The structural properties of GaP(As)N dilute nitrides alloys grown on GaP substrates by molecular-beam epitaxy are investigated. The samples were studied by Raman scattering and high-resolution X-ray diffraction. In this work the impact of lattice mismatch of GaP(As)N layer and GaP substrate on the form of the spectrum of Raman scattering of samples was detected. It was shown that the addition of arsenic in solid solution GaPAsN can compensate the elastic stresses in the crystal lattice, and we can estimate the lattice mismatch between epitaxial layer GaP(As)N and GaP substrate by the intensity ratio of LO_X/TO_r phonon peaks.

Mathematical model of nanostructured field emission surface is proposed. In order to determine geometrical parameters of the surface structure digital processing of scanning electron microscopy images was used. Effective value of local electrical field enhancement factor is defined and calculated within the Fowler-Nordheim theory. It was found effective enhancement factor decreases as the applied electrical field increases for a fixed geometry.

We researched electrical characteristics of GaN nanowires (NWs) grown by MOCVD through solid titanium film. The technology of creating the ohmic contacts and MESFET structure on single NWs has been developed. The optimal annealing temperature of contacts has been found and conductivity structure, the free carrier concentration and mobility has been evaluated.

One-dimensional multilayer structures of periodically alternating low refractive index (silica) and high refractive index (titania) materials have been deposited by sol-gel spincoating. Experimental spectra of the structures are in agreement with spectra calculated by transfer matrix technique. As an example, theoretical and experimental spectra with a stop band corresponding 600 nm-reflection are shown.

Experimental set up for the natural experiment and measurement model are presented to obtain the feld emission energy distribution spectrum out of silicon carbide in case of the macro-sample having a macroscopic shape of a tip. The prototype of feld emission 6H - SiC monolithic cathode is proposed for spectroscopy measurements, and characterised by current-voltage dependence at macroscale interelectrode distance.

By applying the Redlich-Kister polynomial model, we calculate chemical potentials of quaternary liquid alloys during the gold-catalyzed vapor-liquid-solid growth of ternary In_xGa_1-xAs nanowires. We then use these chemical potentials in the Zeldovich nucleation rate to obtain the nanowire axial growth rates versus the deposition conditions and indium compositions.

We investigate the field emission properties of planar graphene structures with nanosized interelectrode distance. The graphene was obtained by thermal decomposition of silicon carbide in vacuum. Planar field emission structures on the basis of graphene on semiinsulating SiC were fabricated by using focused ion beam. We have performed current-voltage measurement on graphene/SiC field emission cathodes. The planar field emission structures showed a threshold voltage less than 1 V.

The GaAs native oxide effect upon the surface morphology of the GaAs epitaxial layer was studied with taking into account the main growth parameters of MBE technology: substrate temperature, effective As₄/Ga flux ratio and growth rate. The MBE modes of atomically smooth and rough surfaces and surfaces with Ga droplet array formation were determined. The possibility of the obtaining of GaAs nanowires via GaAs native oxide layer was shown.

The temperature dependence of the electrical conductivity in Cu₂O thin films grown by magnetron sputtering at room temperature under different rf-power was investigated. Calculated activation energy of the conductivity for copper oxide (I) films linearly increases with increase in sputtering power reflecting an increasing in concentration of gap states.

To modify the structure of detonation nanodiamonds (DNDs) several carboxylate groups were added to DNDs. Activation of COOH-surface functionalized groups allowed attaching of various organic tails to molecules. It was investigated that dielectric and electrooptical properties of nematic liquid crystalline mixtures (LCMs) doped with modified DNDs (MDNDs). It is established that the effect of DNDs on mesomorphic, dielectric and electrooptical properties depends on the size of nanoparticles (NPs) and the type of tail-like organic molecules grafted to DNDs. It is found that NPs of a small size (5-6 nm) do not significantly affect on the parameters of LCMs. At the same time conglomerates of a larger size (50 and 100 nm) depending on the tails polarity can increase or decrease the dielectric anisotropy and response time of LCMs in about 1.2-1.4 times.

The experimental results on synthesis of Si/Ge p-i-n structures with Ge quantum dots in the i-region and their investigation by the method of admittance spectroscopy are presented. The activation energies of the emission process from localized states are calculated for two types of structures. Current-voltage characteristics without illumination and under illumination are measured.

This study investigates an orbital exciton propagation in quasi-two-dimensional Heisenberg antiferromagnet Sr₂IrO₄ by means of computer simulation. Ising and Heisenberg models are compared, taking in consideration magnetic interactions and exciton hopping. As the result of this simulation the spin structure factor for both models is calculated

This work presents the results of experiments on synthesis of carbon nanostructures (CNs) by the method of thermal chemical vapor deposition using iron nanopowders obtained by the method of electrical explosion of wires as catalysts. To study the process of nucleation and growth of individual carbon nanostructures, experiments were conducted not only on nanopowders, but also on the separated clusters. To determine the optimum conditions of the carbon nanostructures synthesis and lower temperature limit, experiments were performed at different temperatures (300-700°C) and pressures (100-400 mbar). The experiments have shown that the lower temperature limit for carbon nanostructures synthesis on the iron nanopowders is 350°C and in this process the growth of carbon nanostructures is not so massive. Stable growth of carbon nanostructures for nanopowders began from 400°C during the entire range of pressures. The analysis of Raman spectroscopy showed that the most optimum conditions for obtaining nanotubes of high quality are P = 100 mbar and T = 425°C.

We present a novel three-jet microreactor design for localized deposition of gallium arsenide (GaAs) by low-pressure Metal-Organic Chemical Vapour Deposition (MOCVD) for semiconductor devices, microelectronics and solar cells. Our approach is advantageous compared to the standard lithography and etching technology, since it preserves the nanostructure of the deposited material, it is less time-consuming and less expensive. We designed two versions of reactor geometry with a 10-micron central microchannel for precursor supply and with two side jets of a dilutant to control the deposition area. To aid future experiments, we performed computational modeling of a simplified-geometry (twodimensional axisymmetric) microreactor, based on Navier-Stokes equations for a laminar flow of chemically reacting gas mixture of Ga(CH₃)₃-AsH₃-H₂. Simulation results show that we can achieve a high-rate deposition (over 0.3 μm/min) on a small area (less than 30 μm diameter). This technology can be used in material production for microelectronics, optoelectronics, photovoltaics, solar cells, etc.

In this paper refining of mathematical model for calculation of parameters of selforganised quantum dots (QDs) of Ge on Si grown by the method of molecular beam epitaxy (MBE) is done. Calculations of pyramidal and wedge-like clusters formation energy were conducted with respect to contributions of surface energy, additional edge energy, elastic strain relaxation, and decrease in the atoms attraction to substrate. With the help of well-known model based on the generalization of classical nucleation theory it was shown that elongated islands emerge later than pyramidal clusters. Calculations of QDs surface density and size distribution function for wedge-like clusters with different length to width ratio were performed. The absence of special geometry of islands for which surface density and average size of islands reach points of extremum that was predicted earlier by the model not taking into account energy of edges was revealed when considering the additional contribution of edge formation energy.

GaAs films with low-temperature GaAs (LT-GaAs) layers were grown by molecular beam epitaxy (MBE) method on vicinal (001) Si substrates oriented 6° off towards [110]. The grown structures were different with the thickness of LT-GaAs layers and its arrangement in the film. The processes of epitaxial layers nucleation and growth were controlled by reflection high energy electron diffraction (RHEED) method. Investigations of crystalline properties of the grown structures were carried out by the methods of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The crystalline perfection of the GaAs films with LT-GaAs layers and the GaAs films without ones was comparable. It was found that in the LT- GaAs/Si layers the arsenic clusters are formed, as it occurs in the LT-GaAs/GaAs system without dislocation. It is shown that large clusters are formed mainly on the dislocations. However, the clusters have practically no effect on the density and the propagation path of threading dislocations. With increasing thickness of LT-GaAs layer the dislocations are partly bent along the LT-GaAs/GaAs interface due to the presence of stresses.

The analysis of the optical properties, including transient photoluminescence (PL), of CdSe quantum dots (QDs) self-assembled in supercrystals shows that supercrystals possess efficient QD PL. Although PL band is slightly broadened and blueshifted as compared with QD colloidal solution, PL kinetic is the same showing absence of induced channels of the energy dissipation. The data indicate the opportunity to create quantum dot solids with efficient PL.

The electronic structure of the multi-layer graphene has been studied using the density functional theory (DFT). The dependence of the average interlayer distance on the number of layers (n = 2 ÷ 6) has been determined. The analysis of the charge redistribution and the electron density of the bi- and three-layer graphene under the external pressure up to 50 GPa has been performed. The model of the interlayer conductivity of compressed multigraphene was offered

This work presents the results of experiments on synthesis of micro- and nanodiamonds by the method of oxy-acetylene torch on the surface of pre-deposited copper thin films. The influence of the thickness of the buffer copper film and the concentration ratio of oxygen and acetylene on the structure formation of the deposited samples was investigated during performed experiments. Studies by Raman scattering and scanning electron microscopy showed that the synthesis of micro- and nano-diamonds occurs under certain experimental conditions.

Done numerically simulated the effects of certain modes of operation on the CVC of field microwave transistors on the basis of heterostructures AlGaN / GaN (HEMT). The results of these studies suggest the possibility of quite efficient use of numerical simulation for the development of HEMT microwave transistors allowing for the real instrument designs.

We report on successful growth by plasma-assisted molecular beam epitaxy on a Si(111) substrate crack-free GaN/AlN buffer layers with a thickness more than 1 μm. The layers fabricated at relatively low growth temperature of 780°C have at room temperature the residual compressive stress of -97 MPa. Intrinsic stress evolution during the GaN growth was monitored in situ with a multi-beam optical system. Strong dependence of a stress relaxation ratio in the growing layer vs growth temperature was observed. The best-quality crack-free layers with TDs density of ∼⃒10⁹ cm^-2 and roughly zero bowing were obtained in the sample with sharp 2D-GaN/2D-AlN interface.

This research presents an automated method of synthesizing semiconductor and metal nanoparticles using flow rector synthesis as a new alternative to the batch method of synthesizing nanoparticles. Experiments were carried out to determine the optimal flow rates of reagents droplets. The reactor was successfully applied to the synthesis of colloidal solutions of semiconductor (CdSe) and metal (Ag) nanoparticles. This instrument is applicable both in material science laboratories and in industry.

This work demonstrates the possibility of using a silicon substrate with nanoscale buffer layer of silicon carbide for growth of GaN nanowires by molecular epitaxy on. Morphological and optical properties of the grown arrays are studied. It is shown that the integral intensity of the photoluminescence of such structures is more than 2 times higher than the best NWs GaN structures without buffer layer of silicon carbide.

This paper presents the results of experimental study of photoluminescence (PL) and surface photovoltage of ZnO synthesized in this study. Two types of zinc oxide samples, prepared by hydrothermal and sonochemical methods at two different temperatures, are contrasted. The observed differences in their PL spectra are associated with different mechanisms of formation and resulting concentration of point defects. At a high-temperature synthesis, blue luminescence band prevails. Reducing the temperature causes the increase in intensity of the yellow-red luminescence band.

We found out the general laws of the current-voltage characteristics hysteresis behavior for emitters of different nanomaterials - graphene, nanotube. Comparison of two power supply modes showed that the IVCs change with growth and decrease of the scanning voltage amplitude in "fast" mode which correlates with current-voltage characteristic hysteresis in "slow" mode. Common patterns forms of current-voltage characteristics in different power supply modes were identified.

This research shows the possibility of carbon nanotubes (CNTs) formation on the surface of low nickel (∼ 10 at.%) Ni-Nb-N amorphous metal alloy film by CVD method at 550 °C of the gas mixture based on acetylene. The structure of CNT were studied by transmission and scanning-electron microscopy, energy-dispersive X-ray and the Raman spectroscopy.

The method of the field emission data online processing of materials, perspective for a nanoelectronics, is developed. The method is based on the slope-intercept diagram analysis of the current voltage characteristics registered during the experiment. It allows to build calibration grids of the microscopic emission parameters, such as work function, effective emission area and field enhancement factor, and and to estimate changes in the sample structure online.

A new numerical approach for the determination of the GaN nanowire surface density on an AlN/Si substrate as a function of the growth time and gallium flux is presented. Within this approach, the GaN island solid-like coalescence and island-nanowire transition are modeled by the Monte-Carlo method. We show the importance of taking into consideration the island coalescence for explaining that the maximum of GaN island surface density is several times larger than the maximum of GaN nanowire surface density. Also, we find that the nanowire surface density decreases with an increase of the gallium flux.

This work addresses the evolution of radius distribution function in self-catalyzed vapor-liquid-solid growth of GaAs nanowires from Ga droplets. Different growth regimes are analyzed depending on the V/III flux ratio. In particular, we find a very unusual selfequilibration regime in which the radius distribution narrows up to a certain stationary radius regardless of the initial size distribution of Ga droplets. This requires that the arsenic vapor flux is larger than the gallium one and that the V/III influx imbalance is compensated by a diffusion flux of gallium adatoms. Approximate analytical solution is compared to the numerical radius distribution obtained by solving the corresponding Fokker-Planck equation by the implicit difference scheme.

We separated AlN/SiC film from Si substrate by chemical etching of the AlN/SiC/Si heterostructure. The film fully repeats the size and geometry of the original sample and separated without destroying. It is demonstrated that a buffer layer of silicon carbide grown by a method of substitution of atoms may have an extensive hollow subsurface structure, which makes it easier to overcome the differences in the coefficients of thermal expansion during the growth of thin films. It is shown that after the separation of the film from the silicon substrate, mechanical stresses therein are almost absent.

A new approach to the high-yield synthesis of nanoparticles in the multi-gap (up to 12) spark discharge generator operating at a repetition rate as high as 2.5 kHz is discussed. This approach allows to increase the production rate by a factor of up to 100 as compared to the conventional approach utilizing single gap generator operating in the self-breakdown mode. In the case of spark erosion of aluminum electrodes in the air atmosphere, the production rate of 300 mg/h has been achieved. From the analysis of transmission electron microscopy images it was found that primary particles of the synthesized material are nearly spherical in shape and their size is 11 nm; these primary particles are united into larger objects (∼80 nm) with fractal structure. The fraction of amorphous phase is 54% and the rest 46% is of cubic γ-Al₂O₃ phase with the mean crystallite size of 12 nm as determined from X-ray diffraction analysis. The specific surface area of the nanoparticles determined by BET method is equal 180 m²/g.

The new technology of the formation of photoresistive structures sensitive in ultraviolet range of electromagnetic spectrum based on lead selenide and lead selenite composite is discussed. Studies of photosensitivity were carried out using a set of LEDs in the visible and ultraviolet spectral range. Obtained structures show considerable sensitivity in ultraviolet and blue range of radiation, meanwhile that in red and yellow region of light turned to be small. The structures were formed by oxidation of PbSe crystals. Diffusion of the oxygen through the surface layer of PbSe was suggested to be a key mechanism of oxidation. Oxidation kinetics were studied by means of roentgen lines chemical shift and roentgen diffraction.

Scanning electron microscopy was used to study structural changes in luminescent alumina ceramics which was synthesized from nanopowder at high temperatures in reducing environment. An effect of synthesis parameters on size-distribution of grains, their shape and a number of pores in the samples under study was determined. It was found that in a certain temperature range grains are the same ones in the precursor nanopowder, which is associated with the emergence of nanoparticles of lower aluminum oxides.

A composite material based on MWCNT covered by pyrolytic Cr has been prepared by MOCVD growth technique using bis(arene)chromium compounds as the pyrolytic Cr source. Their structures and morphologies were preliminary studied by X-ray diffraction and scanning and scanning electron microscopy. The atomic and chemical composition of the interface, MWCNT surface and Cr-coating of the composite were studied by total electron yield mode in the range NEXAFS C1s - and Cr2p - absorption edge with use of synchrotron radiation of RGBL at BESSY-II. The study has shown that top layers of the MWCNT in composite have no essential destruction, the coating of the MWCNT surfaces is continuous and consists of Cr₂O₃. The chromium oxide adhesion is provided by chemical binding between the carbon atoms of the MWCNT top layer and the oxygen atoms of the coating.

Technology for growing layers of InGaAsP solid solutions with Eg ∼⃒ 1.0 - 1.2eV on InP substrates in the spinodal decomposition region by the metalorganic vapour phase epitaxy (MOVPE) technique has been developed. Results of investigation of the obtained solid solution layers by the methods of photoluminescence, reflectance anisotropy spectroscopy and fractal analysis are presented.

In this work we study features of vapor-solid-liquid mechanism of nanowire growth. We consider variation of droplet volume during the growth caused by droplet depletion and refilling. Here we take into account the changes in material transport due to volume variation, which was neglected previously. We also discuss the impact of this effect on nanowire length distributions.

The work under consideration presents research of structure, composition and optical properties of aluminium nitride thin films grown by reactive ion plasma sputtering. Aluminium nitride films are shown to contain amorphous and polycrystalline phases. Amorphous phase presence influences on refraction and absorption indexes. Conditions of polycrystalline films with primary (dedicated) orientation synthesis are revealed.

The thermal roughening of epitaxial GaAs film surface is studied under anneals at temperatures 700-775 °C in the presence of a saturated Ga-As melt. Surface roughening consists in the formation of spiral "inverted pyramids" on the initially flat surface due to the step-flow sublimation induced by screw dislocations. The observed roughening indicates that, despite the presence of As and Ga vapors provided by the melt, the annealing conditions are shifted from equilibrium towards sublimation.

The effectiveness of n-type nitrogen doping of bulk 4H-SiC grown on seeds of different orientation is studied by optical absorption measurements. The 4H-SiC ingots have been grown by physical vapour transport (PVT), with nitrogen doping from the SiC source. The nitrogen concentration was determined at room temperature from the absorption peak intensity at 464 nm, with account for the degree of donor ionization. It has been shown that 4H-SiC ingots grown on Si (11-22) faces are significantly less doped by nitrogen than the ones grown on C (11-2-2).

In this work we study growth of semiconductor GaN nanowires (NWs) on Si(111) substrates by means of molecular beam epitaxy. We demonstrate that the substrate temperature affects both the surface density and growth rate of the synthesized NWs. It was determined that at a fixed flux of nitrogen equal to 1.3 cm³/min the maximum growth rate of NWs is ∼ 38 nm/h at a substrate temperature — 800 ^oC. It was also found that the growth rate of NWs on the substrates treated with the oxide removal procedure is half the growth rate on substrates covered with oxide, while their surface density is twice higher in the first case. In addition we have studied influence of Ga flux on NWs formation.

The tunnel ionization of an electron bounded by two delta potentials under the influence of a constant electric field is considered. The equations for the electron current density for two different initial states are obtained. The dependence of the emission current on the orientation of the potential with respect to the field direction and the distance between them is studied. Appropriate conditions for observation essential interference effects are defined.

This paper investigates the elastic deformation of the structure containing InAs nanoclusters in a pyramid, grown on the substrate GaAs. So far the data have not been grown quantum dots (QDs), one of the reasons is significant difference of periods, which reaches 7%. Ideally atomic plane on the border of QDs and substrate must continuously sews. Due to the difference in lattice periods crosslinking occurring deformations and mechanical stresses, the magnitude of which is proportional to the number of atomic planes, the size of base of the pyramid. Therefore, when you reach a certain size islands (quantum dots), they may experience mechanical stresses p_cr sufficient for the appearance of structural defects - dislocations, fractures.

This article presents the results of a study electrical and optical properties of the thin film system of CdO-LCC. Cadmium oxide films were obtained by method of thermal oxidation. CdO-LCC thin film system was produced by applying on a CdO film a linear chain carbon film in thickness of 100 nm using the ion-plasma method, after which the obtained system was annealed. The studies showed that the obtained CdO-LCC films are quite transparent in the visible region; it has polycrystalline structure, thickness around 300 nm, the band gap to 2.3 eV. The obtained thin film system has photosensitive properties.

In this work we correlated transmission spectra of GaN layers grown on sapphire substrates by hydride vapour phase epitaxy with biaxial stress measured in the layers. It was observed that the sign of stress in the GaN layer is changed by Si doping and growth conditions. Transmission curves are shifted relative to each other depending on the stress in the layer. The cut-off wavelength of the transmission curves has a tendency to shift near parallel to a shorter wavelength range when the GaN layer is under the compression biaxial stress. When the GaN layer is under the tensile biaxial stress the cut off wavelength has a tendency to shift near parallel to a longer wavelength range).

Direct water photoelectrolysis using III-N materials is a promising way for hydrogen production. GaN/AlGaN based p-n structures were used in a photoelectrochemical process to investigate the material etching (corrosion) in an electrolyte. At the beginning, the corrosion performs through the top p-type layers via channels associated with threading defects and can penetrate deep into the structure. Then, the corrosion process occurs in lateral direction in n- type layers forming voids and cavities in the structure. The lateral etching is due to net positive charges at the AlGaN/GaN interfaces arising because of spontaneous and piezoelectric polarization in the structure and positively charged ionized donors in the space charge region of the p-n junction.

Etching of the GaN layers in 1M KOH aqua solution under irradiation was studied by the electro-stimulated photolysis using N₂-laser (337 nm, 60 W/m²) as a light source. It was observed that the size and the depth of the failure monotonically depend on the optical power and the irradiation time of the N₂ laser and the GaN layer type of conductivity. The GaN layers etching rate was evaluated. A mechanism of the failure in the n-GaN layers is discussed.

We study electronic excitation transfer in the complexes of Ag clusters with oligonucleotides. Steady-state fluorescence excitation spectra show that the excitation energy is transferred to Ag cluster from all the 30 nucleobases of a 15-mer DNA duplex. This is in contrast to DNA-dyes complexes, where the energy transfer to the dye occurs from neighboring DNA bases only. Fluorescence decay curve for the DNA duplex shows that the process of energy transfer occurs within <100 fs. The obtained results suggest coherent excitonic type of the transfer rather than trivial Forster mechanism.

The aim of this work was to determine a design of a microfluidic droplet generator which provides the best mixing of two components within a droplet during its formation. Simulation of droplets' formation in various designs of microfluidic generators was performed. Dependences of a mixing index from a capillary number and a viscosity of continuous phase were obtained for each design. The mixing index was determined directly after the formation of the droplet. It was found that the small capillary numbers correspond to the lower mixing index due to increase of the droplets diameter. The high viscosity of the continuous phase provides vortex flows in the area of droplet formation which leads to an increase in the mixing index for asymmetric designs, but has no significant effect on the mixing in conventional symmetric flow focusing. So for the asymmetric droplet generator designs the mixing index increases up to 1.5 as compared with the conventional flow focusing designs.

A theoretical model is presented to simulate the growth and nucleation of protein lysozyme crystals by counter diffusion method. The comparison of experimental and simulation results shows that the numerical solution accurately describes the initial stages of crystallization. The developed model can be used to describe crystallization processes with various counter diffusion experiment parameters.

The efficiency carious preventive methods was detected with the use of equipment for IR-spectromicroscopy and high-intensive synchrotron radiation. The results of the experiment are indicative of the use of exogenous caries prevention alone (use of a toothpaste) being inadequate in saturating hard dental tissues by mineral groups and, thus, keeping teeth healthy, as this method is only short-lived. The use of endogenous methods (mineral tablets based on calcium glycerophosphate) in combination with exogenous prevention enhances prevention as part of remineralisation of dental tissues.

This work is devoted to the investigation of sizes and concentrations of particles in blood plasma by dynamic light scattering (DLS). Blood plasma contains many different proteins and their aggregates, microparticles and vesicles. Their sizes, concentrations and shapes can give information about donor's health. Our DLS study of blood plasma reveals unexpected dependence: with increasing of the particle sizes r (from 1 nm up to 1 μm), their concentrations decrease as r_-4 (almost by 12 orders). We found also that such dependence was repeated for model solution of fibrinogen and thrombin with power coefficient is -3,6. We believe that this relation is a fundamental law of nature that shows interaction of proteins (and other substances) in biological liquids.

We have synthesized and investigated structural and functional properties of plasmid DNA complexes with multi-walled carbon nanotubes (MWCNTs) for detection of changes in structural state of the plasmid DNA at its recognition by site-specific endonuclease. It has been also established that the site-specific endonuclease is functionally active on the surface of MWCNTs.

Registration of neuronal bioelectrical signals remains one of the main physical tools to study fundamental mechanisms of signal processing in the brain. Neurons generate spiking patterns which propagate through complex map of neural network connectivity. Extracellular recording of isolated axons grown in microchannels provides amplification of the signal for detailed study of spike propagation. In this study we used neuronal hippocampal cultures grown in microfluidic devices combined with microelectrode arrays to investigate a changes of electrical activity during neural network development. We found that after 5 days in vitro after culture plating the spiking activity appears first in microchannels and on the next 2-3 days appears on the electrodes of overall neural network. We conclude that such approach provides a convenient method to study neural signal processing and functional structure development on a single cell and network level of the neuronal culture.

Dissolution and mixing of flavin mononucleotide (FMN), which activates a luminescent reaction, were considered in various designs of microfluidic chip for pollution analysis of liquid samples. The aim was to determine the velocity mode of fluid flow ensured the uniform distribution of the FMN in the reaction chamber. Simulation of concentration distribution of FMN in various designs of microfluidic chips was conducted. It was shown that the passive mixing techniques based on the constant flow rate didn't provide mixing of FMN in acceptable time (3 seconds). The most efficient mixing was achieved using variable flow rate with a gradually increasing frequency of oscillation.

Visualization of the structure of biological objects plays a key role in medicine, biotechnology, nanotechnology and IT-technology. Atomic force microscopy (AFM) is a promising method of studying of objects' morphology and structure. In this work, AFM was used to determine the size and shape of the bacterial strains of Escherichia coli M-17 and visualization its interaction with the nanoparticles of zinc oxide. The suspension of E.coli bacteria was applied to natural mica and studied by contact mode using the FemtoScan multifunctional scanning probe microscope.

This work proposes an explicit analytical model for the surface potential of a colloidal nano-agglomerate. The model predicts that when an agglomerate reaches a certain critical size, its surface potential becomes independent of the agglomerate radius. The model also provides a method for identifying and quantifying the solute-indifferent charge in nanocolloids, that allows to assess the stability of toxicologically significant parameters of the system.

The great need of the people to bread demands to increase high qualitative grain plants. At present time for solving these problem different methods of biochemistry, genetics and molecular biology are widely used in the process of selection. To investigate biochemical peculiarities of wheat-aegilops hybrids and to define the correlative relation between these characteristics. To investigate the technological peculiarities of wheat- aegilops hybrids and to define the relation between their main biochemical and technological characteristics. The conclusion of this investigation showed the followings- the wheat-aegilops hybrids according to their morphological and biochemical characteristics have approached to wheats. The electrophoretic spectres of the wheat- aegilops hybrids which have stable for their morphological characteristics are homogeny and heterogenic. Hereditarily some group protein components have passed to their tribes from their parents. But spontaneous hybridisation results in taking part the components of other unknown wheats in these electrophoretic spectres. There is a relation between the electrophoretic spectres and the indications of the grain quality.

Switching assay was applied for the detection of antigen-antibody interaction between 70-kDa heat shock protein (Hsp70) and anti-Hsp70 monoclonal antibodies in water solutions using conjugates with magnetic iron oxide nanoparticles (MNPs). Hsp70 is a ubiquitous intracellular protein that plays a crucial role in cancerogenesis and many other pathologies. Detection of the Hsp70 level in the biological fluids might have a prognostic and diagnostic value in clinic. The developed switch assay for the detection of Hsp70 demonstrated high sensitivity for antigen-antibody interaction analysis thus proving its potential for further preclinical and clinical studies.

It has been shown that exposure to radiation of LED sources of light with an emission band maximum at about 465 and 520 nm having substantially identical damaging effects on animal cells in culture, that are in a logarithmic growth phase and preincubated with pigment. Photobiological effect is caused by photodynamic processes involving singlet oxygen generated by triplet excited sensitizer. Mono-exponential type dependence of cell survival on the energy dose indicates that it is bilirubin that acts as a sensitizer but not its photoproducts. The inclusion of bilirubin in the cells, where it is primarily localized in the mitochondria cells, it is accompanied by multiple amplification photochemical stability compared to pigment molecules bound with albumin

The results of the study of human aortic walls, subjected to different stages of mineralization are presented. By means of scanning electron microscopy and X-ray microanalysis the morphology, elemental composition and characteristics of the mineral component localization were investigated. The key differences in the initial, intermediate and final stages of pathological mineralization of the aorta wall were identified. The data obtained may be useful in describing the mechanism of biomineral deposits formation in human body.

A novel regularity of hierarchical structures is found in the formation of chiral biological macromolecular systems. The formation of structures with alternating chirality (helical structures) serves as an instrument of stratification. The ability of a carbon atom to form chiral compounds is an important factor that determined the carbon basis of living systems on the Earth as well as their development through a series of chiral bifurcations. In the course of biological evolution, the helical structures became basic elements of the molecular machines in the cell. The discreteness of structural levels allowed the mechanical degrees of freedom formation in the molecular machines in the cell.

Super-resolution microscopy is a promising tool for the field of microbiology, as bacteria sizes are comparable to the resolution limit of light microscopy. Bacterial division machinery and FtsZ protein in particular attract much attention of scientists who use different super-resolution microscopy techniques, but most of the available data on FtsZ structures was obtained using two-dimensional (2D) super-resolution microscopy. Using 3D single-molecule localization microscopy (SMLM, namely dSTORM) to visualize FtsZ, we demonstrate that this approach allows more accurate interpretation of super-resolution images and provides new opportunities for the study of complex structures like bacterial divisome.

Optogenetic is a powerful method that allows to modulate cellular physiological properties. In our article, we demonstrate changes of electrical properties of cellular membranes on HEK-293T and hippocampal neurons transfected with channelrhodopsins and halorhodopsins induced by blue and orange light stimulation.

In the present work porous PLA scaffolds filled with micro- and nano- HA were studied. Both composites with micro- and nano-HA were obtained by extrusion in the same conditions. Scaffolds were obtained by 3D-printing by fused filament fabrication method. Structure of porous scaffolds was pre-modeled by computer software. Compression and three - point flexural tests were used to study mechanical properties of the scaffolds.

Luminescent metal clusters are a subject of growing interest in recent years due to their bright emission from visible to near infrared range. Detailed structure of the fluorescent complexes of Ag and other metal clusters with ligands still remains a challenging task. In this joint experimental and theoretical study we synthesized Ag-DNA complexes on a DNA oligonucleotide emitting in violet- green spectral range. The structure of DNA template was determined by means of various spectral measurements (CD, MS, XPS). Comparison of the experimental fluorescent excitation spectra and calculated absorption spectra for different QM/MM optimized structures allowed us to determine the detailed structure of the green cluster containing three silver atoms in the stem of the DNA hairpin structure stabilized by cytosine-Ag+-cytosine bonds.

This work represents the real steps to development and design advanced two-photon microscope by efforts of laboratory staff. Self-developed microscopy system provides possibility to service it and modify the structure of microscope depending on highly specialized experimental design and scientific goals. We are presenting here module-based microscopy system which provides an opportunity to looking for new applications of this setup depending on laboratories needs using with galvo and resonant scanners.

Recent years, optogenetic method of scientific research has proved its effectiveness in the nerve cell stimulation tasks. In our article we demonstrate an implanted device for the spinal optogenetic motoneurons activation. This work is carried out in the Laboratory of Molecular Neurodegeneration of the Peter the Great St. Petersburg Polytechnic University, together with Nano and Microsystem Technology Laboratory. The work of the developed device is based on the principle of combining fiber optic light stimulation of genetically modified cells with the microelectrode multichannel recording of neurons biopotentials. The paper presents a part of the electrode implant manufacturing technique, combined with the optical waveguide of ThorLabs (USA).

Samples of fresh excised tissues obtained from patients who had undergone gastric cancer have been investigated. Samples were consisted of cancer zone, normal zone and zone mixed of normal and cancer tissues. Their optical properties and spectral features were investigated by terahertz time-domain spectroscopy (TDS) in reflection mode. It was found that waveforms of reflected signals from normal and cancer tissues were well distinguished so it can be concluded that it is easy to discriminate gastric cancer tissue from normal by using THz TDS.

There were demonstrated capabilities of the Memory Function Formalism (MFF) in analyzing cross correlations in human brain bioelectric activity at obsessive-compulsive disorder (OCD). To extract the information about collective phenomena in (electroencephalogram) EEG brain activity we use the power spectra of memory functions and the memory quantifiers. We discover the pairs of the electrodes with the greatest differences in dynamic and stochastic parameters for patients with the different condition. The high OCD condition is characterized by the influence of the memory effects. The MFF cross correlation analysis allow to describe the collective phenomena in EEG dynamics at OCD including the dynamic, spectral and stochastic behavior.

The reasearch main objective is to obtain ceramic laser materials based on pure YAG (Y₃Al₅O₁₂) and Nd doped YAG (Y_3-xNd_xAl₅O₁₂, with × = 0.5 and 1.0 at. %), by conventional solid state reaction method. Stoichiometric compositions of Y₃Al₅O₁₂ (YAG), Y_2.985Nd_0.015Al₅O₁₂ (0.5 at.% Nd:YAG) and Y_2.97Nd_0.03Al₅O₁₂ (1.0 at.% Nd:YAG) were prepared using high purity Y₂O₃ (99.999%), Al₂O₃ (99.999%) and Nd₂O₃ (99.999%) nanopowders. Green bodies were sintered at 1750 °C for 16 h under vacuum (1.0 × 10^-3 Pa) and then annealed at 1450 °C for 10 h in the air.

Edge emitting quantum dot (QD) lasers are discussed. It has been recently proposed to use modulation p-doping of the layers that are adjacent to QD layers in order to control QD's charge state. Experimentally it has been proven useful to enhance ground state lasing and suppress the onset of excited state lasing at high injection. These results have been also confirmed with numerical calculations involving solution of drift-diffusion equations. However, deep understanding of physical reasons for such behavior and laser optimization requires analytical approaches to the problem. In this paper, under a set of assumptions we provide an analytical model that explains major effects of selective p-doping. Capture rates of elections and holes can be calculated by solving Poisson equations for electrons and holes around the charged QD layer. The charge itself is ruled by capture rates and selective doping concentration. We analyzed this self-consistent set of equations and showed that it can be used to optimize QD laser performance and to explain underlying physics.

Electrically driven microdisk lasers with top contacts made of a semitransparent conducting pyrolytic carbon film are developed. Electrical properties of the pyrolytic carbon contact to a p-type doped GaAs epitaxial layer are studied. Room temperature electroluminescence spectra from an array of the microdisk lasers and a single 27 μm in diameter microdisk laser are demonstrated.

Defect properties of Ga(In)P(NAs) layers with different composition were studied by admittance spectroscopy. For nitrogen content layers the defect level with energy of 0.44-0.47 eV, which related to nitrogen incorporation into GaP, was observed. Its concentration is lower for GaPNAs layers compared to GaPN/InP due to better compensation by arsenic than by indium in lattice of GaP. Other defect level with energy of 0.30 eV was detected in GaPAs and GaPN/InP layers. Likely, the both observed defects in GaPAs and GaPN/InP have the same nature.

The possible mechanisms of the polarization control in single-mode intracavity- contacted vertical-cavity surface-emitting lasers (IC-VCSELs) with the rhomboidal selectively- oxidized current aperture were investigated. It was found that the lasing emission polarization of all single-mode VCSELs is fixed along the minor diagonal of the rhomboidal-shape aperture (the [110] direction). Numerical modelling of carrier transport did not reveal any sufficient injection anisotropy in the laser active region, while the transverse optical confinement factors calculated for the fundamental mode with two orthogonal polarizations are identical. Optical loss anisotropy and/or gain anisotropy are the most likely mechanisms of inducing the polarization fixation.

We propose a model for operation of mode-locked (ML) quantum-well semiconductor laser consisting of a reverse biased saturable absorber and a forward biased amplifying section. To describe the dynamics of this laser we use the traveling wave model. Numerical simulations performed for the InGaAs/InGaAlAs laser structure emitting at 1,55 um.

In this paper Monte-Carlo modeling is in use in order to further approve and quantify the concept of effective transport level in the respect to organic materials with correlated disorder. We consider a model of dipole glass (simple cubic lattice, which sites are occupied by randomly oriented dipoles). Both the absolute values and dependence of the effective transport level on the disorder and temperature, in the limit of low electric field, is very similar to the same in the case of uncorrelated disorder

We present algorithmic solutions aimed on post-processing procedure for industrial quantum key distribution systems with hardware sifting. The main steps of the procedure are error correction, parameter estimation, and privacy amplification. Authentication of classical public communication channel is also considered.

Photoluminescence and electrical properties of superlattices with thin (1 to 5 nm) alternating silicon-rich silicon oxide or silicon-rich silicon nitride, and silicon oxide or silicon nitride layers containing silicon nanocrystals prepared by plasma-enhanced chemical vapor deposition with subsequent annealing were investigated. The entirely silicon oxide based superlattices demonstrated photoluminescence peak shift due to quantum confinement effect. Electrical measurements showed the hysteresis effect in the vicinity of zero voltage due to structural features of the superlattices from SiOa₉₃/Si₃N₄ and SiN₀.₈/Si₃N₄ layers. The entirely silicon nitride based samples demonstrated resistive switching effect, comprising an abrupt conductivity change at about 5 to 6 V with current-voltage characteristic hysteresis. The samples also demonstrated efficient photoluminescence with maximum at ∼1.4 eV, due to exiton recombination in silicon nanocrystals.

InGaN/GaN nanorod structure for light emission diode fabricated by the reactive plasma etching through the self-assembled Ni nano-cluster mask is presented. Fabricated array structure, presented in the form of truncated cones with average diameter height and period of nanorods is 250±50 nm, 430nm and 650±50 nm, respectively. The side angle of single structure about 80^o. EL spectrum has maximum at 460 nm.

In this paper we demonstrate that balanced optical-microwave phase detectors (BOMPD) are able to provide a robust long-term optical-RF synchronization with subfemtosecond residual timing drift over 24 hours in laboratory conditions without active temperature control of optical and electronic paths. Moreover, 10.833 GHz Sapphire-loaded cavity oscillator (SLCO) was successfully disciplined by 216.66 MHz laser oscillator using the BOMPD which resulted in a sub-femtosecond RMS jitter integrated from 1 Hz to 1 MHz.

In this paper, we demonstrate the effect of surface recombination on spectral sensitivity of structures based on gallium arsenide phosphide solid solutions. Simulation of the effect for structures based on a p-n junction and a Schottky barrier was carried out. Photodetectors with different rates of surface recombination were fabricated by using different methods of preliminary treatment of the semiconductor surface. We experimentally demonstrated the possibility to control photodetector selectivity by altering the rate of surface recombination. The full width at half maximum was reduced by almost 4 times, while a relatively small decrease in sensitivity at the maximum was observed.

Metamorphic Ga_0.76In_0.24As heterostructures for PV converters of 1064 nm laser radiation have been grown by the MOCVD. Parameters of the GaInAs metamorphic buffer layer with a stepwise profile of In composition variation were calculated. Its epitaxial growth conditions have been optimized, which allowed improving collection of charge carriers from the n-GaInAs base region and obtaining the photo-response quantum yield of 83% at 1064 nm wavelength. It has been found that, due to discontinuity of valence bands at the In_0.24Al_0.76As- p/Ga_0.76In_0.24As-p heterointerface (window/emitter) a potential barrier for holes arises as a result of low carrier concentration in the wide-band-gap material. The use of InAlGaAs solid solution with Al concentration of < 40% has allowed raising the holes concentration in the wide-band-gap window, eliminating completely the potential barrier and reducing the device series resistance. Optimization of the PV converter metamorphic heterostructure has resulted in obtaining 1064 nm laser radiation conversion efficiency at the level of 38.5%.

The article shows the possibility of using the threshold current for evaluating the quality of green InGaN/GaN LEDs. It was determined that the current threshold correlated with the position of the maximum of the current dependence of external quantum efficiency, and a concentration gradient of charge carriers in the heterostructure.

A new approach to the silicon based heterostructures technology consisting of the growth of III-V compounds (GaP) on a silicon substrate by low-temperature plasma enhanced atomic layer deposition (PE-ALD) is proposed. The basic idea of the method is to use a time modulation of the growth process, i.e. time separated stages of atoms or precursors transport to the growing surface, migration over the surface, and crystal lattice relaxation for each monolayer. The GaP layers were grown on Si substrates by PE-ALD at 350°C with phosphine (PH3) and trimethylgallium (TMG) as sources of III and V atoms. Scanning and transmission electron microscopy demonstrate that the grown GaP films have homogeneous amorphous structure, smooth surface and a sharp GaP/Si interface. The GaP/Si heterostructures obtained by PE-ALD compare favourably to that conventionally grown by molecular beam epitaxy (MBE). Indeed, spectroscopic ellipsometry measurements indicate similar interband optical absorption while photoluminescence measurements indicate higher charge carrier effective lifetime. The better passivation properties of GaP layers grown by PE-ALD demonstrate a potential of this technology for new silicon based photovoltaic heterostructure

The X-ray luminescence and photoluminescence of the ultradispersed Gd₂O₃ powders with different purity were investigated in 90-360 K temperature range. Both impurity and intrinsic optical active centers were detected. The effect of energy transfer from Gd³+ to RE³⁺ ions was observed.

Subcarrier wave quantum key distribution systems demonstrate promising capabilities for secure quantum networking. However for this class of devices no implementation of secure decoy states protocol was developed. It leaves them potentially vulnerable to photon-number splitting attacks on quantum channel and limiting the key distribution distance. We propose a practical solution to this problem by calculating the required parameters of light source and modulation indices for signal and decoy states in a subcarrier wave system and describing the corresponding experimental scheme.

In the work, a procedure for simulating I-V characteristics of multijunction solar cells (MJ SCs) with accounting for the processes of current relaxation determined by the luminescent coupling between separate p-n junctions has been considered. The effect of the mentioned above processes on the I-V characteristic shape was investigated. It has been shown that, in the case of well pronounced reemission processes in high- efficient MJ SCs, in recording their I-V characteristics, variation of fill factor and rise of the open circuit voltage values being registered take place.

The method of constructing of the optical image of the magnetic field intensity spatial structure distribution with the help of the ferrofluid cell is considered. The experimental research results showed, that the suggested method allows to determine in real time besides the intensity lines structure also the irregularity of the magnetic field and its direction. The possibility of the magnetic system tuning with the help of intensity field lines optical image was examined having in view the realization of necessary field parameters in the course of the experiment. The experimental research results of the magnetic system constructing and tuning quality at different temperatures are represented.

We report on the observation of helicity dependent photocurrent of the 20 μm thick silver-palladium (Ag/Pd) films manufactured by the thick-film technology. The transverse photocurrent is observed at oblique incidence of laser radiation with different wavelengths in the spectral range of 266 - 2100 nm. At the wavelength range of 532 - 2100 nm the polarity of the transverse photocurrent is positive (negative) for the left- (right-) circular polarized beam. We show that action of high temperature on the films in vacuum results in the decrease of longitudinal photocurrent due to the reduction of PdO content. The photon drag effect is suggested to be the origin of the polarization-sensitive photocurrent in the Ag/Pd films. The obtained results show that the Ag/Pd resistive films may be of interest for polarization- sensitive measurements.

In order to increase the betavoltaic batteries efficiency output characteristics of the p^--n⁺ (n^--p⁺) - structures were simulated. Replacing the p⁺-n-structures on the p-n+ and n-p⁺ -structures enables the space-charge expansion to the crystal surface and thus to reduce the recombination loss in the heavy doped p⁺-layer and improve conversion of betavoltaic elements efficiency.

Specific features of investigation of the fluid flow structure in a pipeline by photometric techniques are considered. The applicability of the photometric techniques based on the Doppler effect to such studies is discussed. A new method for detecting defects on inner walls of a pipeline that involves the use of the laser radiation scattered from particles in a flowing fluid is suggested.

Multijunction solar cells grown on Si substrates using III-V compounds are very promising due to potentially high efficiency (over 40%). In that case homojunction in silicon can be replaced with GaP heterojunctions which can be more effective in terms of lowering surface recombination. Silicon substrates of both n- and p-type doping were used to form GaP/Si anisotype heterostructures. It was demonstrated that for p-GaP/n-Si structures charge carrier transport is mainly blocked due to large value of valence band offset at the heterointerface. For n-GaP/p-Si solar cells optimal thickness and doping level were calculated using AFORS-HET software. The influence of interface states density and GaP layer parameters was investigated.

In this work the experimental results of investigations of the dynamics of accumulation and spatial distribution of electrically active radiation defects when irradiating epitaxial films of Hg_1-xCd_xTe (MCT) with different material composition (x). The films, grown by molecular beam epitaxy (MBE) were irradiated by B ions at room temperature in the radiation dose range 10¹² -10¹⁵ ions/cm² and with ion energy 100 keV. The results give the differences in implantation profiles, damage accumulation and electrical properties as a function of the material composition of the films.

In this paper the influence of the volume discharge of nanosecond duration formed in a non-uniform electric field at atmospheric pressure on samples of epitaxial films HgCdTe (MCT) of p-type conductivity. It is suggested that after exposure on film surface oxide layer was formed. This layer has a built positive charge that leads to the formation of an inversion layer which "shunts" the rest of the sample so that the measured field dependence of Hall coefficient corresponds to the material of n-type of conductivity.

We investigate the properties of the photosensitivity spectra of the UV photodetectors based on natural diamond. The effect of the structural defects associated with nitrogen impurities to the photosensitivity is analyzed. We confirm that the polychrome light bias application enhances the photosensitivity of these detectors in the spectral range 240-340 nm due to the quasi-two-photon absorption which originates due to the complicated structure of the band gap impurity states of a natural diamond. The possibility to influence the photosensitivity spectra in the λ<220 nm spectral range of these detectors by the polychrome light bias application is revealed.

This work is devoted to the morphology and electrical properties optimization of flexible photoanodes based on anodic titanium oxide nanotubular arrays (TiO₂-NTAs) for solar cells with extremely thin absorbing layer (ETA-cells) by TiO₂-nanographite thin composite layer formation on the TiO₂-NTAs surface. First, the carbon doped TiO₂-NTAs were synthesized by annealing of the as-anodized TiO₂-NTAs in argon without foreign carbonaceous precursor. The residual ethylene glycol absorbed on the nanotube wall during anodization serves as the carbon source and the C species are uniformly distributed along the entire nanotube to form the C-TiO₂ NTAs. Further decorating of C-TiO₂-NTAs surface by TiO₂ nanoparticles to form the TiO₂-nanographite (NG) composite layer with high conductivity and increased photoanode effective area showed improved ETA-cells performance.

It was shown that the contribution of 3D nanoscale indium fluctuations into the efficiency droop at j < 50 A/cm² can be very high and results in different shapes of the efficiency dependency on current η(j) in blue and green LEDs. Reducing 3D nanoscale indium fluctuations can decrease the efficiency droop in these LEDs. The contribution of delocalized carriers is predominant at j > 50 A/cm² and the current dependences of efficiency, approximated by as η (j) α j^-b where 0.2 < b < 0.3, are alike in both green and blue LEDs.

We investigate the possibility of using diffractive microaxicons with different periods for power conversion efficiency enhancement in solar cells. The microaxicons were manufactured by using electron beam lithography. The parameters of the manufactured microaxicons were measured using scanning electron microscopy (SEM). For imitation of solar light, we utilised a tunable laser (the used wavelength range is from 400 nm to 800 nm). Experimentally measured dependence of solar cell efficiency for the case of a combination of a solar cell and microaxicons of various types demonstrates a power conversion efficiency enhancement in the case of using such structures.

The luminescent organic ITO/TPD/Alq3/Al structures and CdSe/ZnS quantum dots (QD) arrays were created. Electrical and optical properties of the samples were examined. The luminescence of the layers and QD arrays was shown in the range of wavelengths from 400 to 680 nm. Luminescent structures with phosphors corresponding to the emission standards with CRI>98 and with color temperature of 5500 K and 6504 K were created.

In this paper we consider the dependence of the supported modes and the type of its polarization on the profile of the waveguide. Investigated possibility of production of beam splitters designed on the conventional waveguide.

Indium tin oxide (ITO) films have been a subject of extensive studies in fabrication of micro-electronic devices for opto-electronic applications ranging from anti-reflection coatings to transparent contacts in photovoltaic devices. In this paper, a new and effective way of reactive ion etching of a conducting indium-tin oxide (ITO) film with Carbon tetrachloride (CCl₄) has been investigated. CCl₄ plasma containing an addition of gases mixture of dissociated argon and oxygen were used. Oxygen is added to increase the etchant percentage whereas argon was used for stabilization of plasma. The etching characteristics obtained with these gaseous mixtures were explained based on plasma etch chemistry and etching regime of ITO films. An etch rate as high as ∼20 nm/min can be achieved with a controlled process parameter such as power density, total flow rate, composition of reactive gases gas and pressure. Our Investigation represents some of the extensive work in this area.

Presents results of a study of the red luminescence of living plants at room temperature. The analysis of obtained results allows to conclude that the photoluminescence spectra for green leaves in all cases represent the two closely spaced bands.

GaN/AlGaN p-n heterostructures emitting in UV spectral range obtained by HVPE approach were investigated. It was shown that the peak wavelength of UV LEDs was in the range of 360-380 nm with FWHM of 10-13 nm. At operating current of 20 mA, the active region temperature T_j was 43°C, the output optical power and efficiency - 1.14 mW and 1.46%, respectively. The model based on corpuscular Monte Carlo method for calculation of the light extraction index was presented. The simulation results allow us to propose the ways to increase the efficiency of UV LEDs: surface interfaces texturing, optimization of the design of heterostructures, and the use of lenses.

An influence of various parameters of a photoelectrochemical cell (PECC) having a GaN working electrode on the photocurrent was studied. Type of the aqua electrolyte (alkaline (KOH)-, neutral salt (Na₂SO₄)- and acid (H₂SO₄)- based electrolytes) influences on transient time for the photocurrent stabilization. A transient time for the photo current stabilization was observed under illumination by the UV LED light sources. The shortest transient time and the highest photocurrent were observed in the alkaline-based electrolyte (∼0.5M KOH) with n- GaN working electrodes (N_D-N_A =(3-5)×10¹⁶ cm^-3). PECC with electrolytes based on sodium sulfate and sulfuric acid demonstrated longer transient time (up to ten minutes) for the photocurrent stabilization and smaller photocurrent.

Temperature characteristics of InAs/InGaAsP quantum dot (QD) lasers synthesized on InP (001) substrate are presented. The lasers demonstrate high temperature stability: a threshold current characteristic temperature as high as 205 K in the temperature range between 20 to 50°C was measured. Lasing wavelength of 1.5 μm was achieved by covering QDs with 1.7 monolayers of GaAs.

Optically pumped 3-6μm in diameters microdisk lasers with InGaAsN/GaAs quantum well active region has been studied. Single-mode CW lasing at 78K temperature in microdisk laser with 3 μm diameter is demonstrated.

We present an overview of our theoretical and experimental work on a novel type of semiconductor lasers - quantum well (QW) lasers with asymmetric barrier layers (ABLs). Our experimental work supports our theoretical derivations — ABL QW lasers demonstrate superior operating characteristics as compared to conventional QW lasers. In particular, the threshold current is lower and more temperature-stable, the light-current characteristic is more linear, and the wall-plug efficiency is higher in ABL lasers.

We propose a novel strategy for self-adjusted fabrication of large-scale array of resonant silicon nanoparticles (metasurface) on a thin silicon film. The self-adjusting mechanism is based on the effect of resonant nanogratings formation under intense multishot femtosecond irradiation of a thin silicon film. The resulting metasurfaces allow for generation of ultraviolet laser pulses at a wavelength of 270 nm with conversion efficiency up to 10^-6 and high peak (≈100 kW/sm²) and average power (≈1.5 μW). Such high peak power from ultrathin metasurface makes the generated UV pulses applicable in a wide range of applications: precise nanolithography, ultrafast photoexcitation etc.

In present work the results of investigation of optical (transmission spectra) and plasmonic (surface plasmon-polariton resonance) properties of ultrathin and nanostructured Au films are presents. Methods and techniques for the syntheses of samples of ultrathin and nanostructured metallic films, and for the experimental studies of optical and plasmonic properties are representative. Au films on SiO₂ (optic glass) substrates were investigated.

The article discusses the results of investigations of porous films of alumina, formed into oxalic electrolyte with addition surface active agents, in particular, ordering structure, roughness of a surface, the optical transparency of the electrolyte concentration and surface active agents. Also discusses the features of the formation of porous films of temperature and IR radiation.

Method of dry e-beam etching of resist (DEBER) is described. It appears that the method could be extremely useful for formation of wide range of structures for optics and optoelectronics. It is relatively simple to form diffraction or binary gratings, some diffractive optical elements (DOE), 3D structures or planar photonic crystals. Method could be realised in any focused e-beam induced process (FEBIP) system or in e-beam lithographer with minor modifications. DEBER method is significantly more productive than standard or grayscale e- beam lithography. Typical exposure time for 3x3.9 mm² area is about 10-100 s. Examples of structures formed by the DEBER method that could be used in optoelectronics are presented.

We propose to control design of organometallic conducting Langmuir monolayer by utilizing geometrodynamic approach. By means of this approach the compressibility of the monolayer, which consists of molecules of thiophene-pyrrole series oligomer with covalently bound hydrophobic alkyl chain, has been analyzed for different subphase with iron salts. It has been discovered that the monolayers are polymerized and turn into monolayers of nanocyclic organometallic coordination compounds at a two-dimensional phase transition of the first order.

An exciton-polariton condensate formed in a semiconductor microcavity coupled to an exciton reservoir in the strong coupling regime is studied. The condensate is trapped in onedimensional periodic potential, and we work in the centre of Brillouin zone. We develop a model for coupled three spatial harmonics of mean field. Using the simplified model we get important analytical relations for polaritonic eigenstates and band-structure. The analytical results are supported by numerical analysis. The strong influence of external potential and nonlinearity is discussed and the feedback induced by the inhomogeneity of the incoherent reservoir on the dynamics of coherent polaritons.

We present photoluminescence studies of AI_xGa_1-xN/Al_yGa_1-yN (y = x+0.3) quantum well (QW) heterostructures with graded AI content in barrier layers, emitting in the range 285-315 nm. The best-established internal quantum efficiency of the QW emission is as high as 81% at 300 K, owing to enhanced activation energy of charge carriers and exciton binding energy in the QW heterostructure with optimized design.

We develop a novel method of core-shell nanoparticles fabrication based on laser ablation of multilayer thin films using femtosecond laser pulses. Transmission electron microscopy proves that the obtained structures have Si and Au separated parts. We theoretically show that the combination of high refractive index dielectric and plasmonic nanoparticles shows possibility of interplay between magnetic optical responses and plasmon resonances. This opens a possibility to manipulate by both scattering power pattern and local optical field enhancement via precise engineering of the core/shell nanoparticles.

The surface integral equations method is used to analyse the surface plasmon resonance position in a metal island film formed by non-interacting axisymmetrical prolate/oblate hemispheroids placed on a dielectric substrate. The approach is verified via the comparison of results obtained for a hemisphere on a substrate with the ones obtained using the multipole expansion method. The preference of the integral equations method is in obtaining a simple final analytical expression for a particle polarizability in which any dielectric function of a metal can be substituted. Such simple formulae for the hemispherical particle on the substrate and calculated dependences of the hemispheroid resonant wavelength on its aspect ratio are presented.

It is represented the results of modelling of magnetooptical properties in reflection polar geometry of one-dimensional photonic crystal, in which highly Bi-substituted iron garnet defect of composition Bi_1.0Y_0.5Gd_1.5Fe_4.2A_l0.8O₁₂ / Bi_2.8Y_0.2Fe₅Oi₂ is located between the dielectric Bragg mirrors (SiO₂ / TiO₂)^m (were m is number of layer pairs) and buffer SiO₂ and gold top layers of different thicknesses is placed on structure. The modification of spectral line- shapes of microcavity and Tamm plasmon-polariton modes depending on m is found.

In this work we developed a design of one-dimensional Si/SiO2 photonic crystal slab supporting so called optical bound states in the continuum - infinitely high-Q optical states with energies lying above the light line of the surrounding space. Such high-Q states are very perspective for many potential applications ranging from on-chip photonics and optical communications to biological sensing and photovoltaics.

Polar optical phonons in the binary AlN/GaN superlattices (SL) were studied in the framework of dielectric continuum model (DCM). It is shown that the modes propagating in the interface plane are delocalized over all layers and the modes propagating along the SL axis are delocalized in certain layers. Frequencies of former strongly depend on the layer thickness ratio and frequencies of the latter do not depend on the SL structure. Such behavior is typical for the short-period SL. We show that a strong coupling between two types of the modes takes place at increasing SL period. The phenomenon is described mathematically by the frequency- structure relations and its physical meaning is discussed.

Birefringence in double tunnel-coupled GaAs/AlGaAs quantum wells was studied in the mid-infrared spectral range close to the intersubband resonance. Phase-sensitive optical studies allowed us to deduce simultaneously the differences of the refraction index and absorption coefficient for the normal waves polarized in the plane of the structure and along the structure growth, including electric-field induced effects. The optical absorption data are in a good agreement with the direct optical transmission measurements.

Fluorescent properties of silver and copper doped zinc-phosphate glasses were studied. By X-ray irradiation of silver and copper co-doped glasses we could create and identify new emission centers which do not exist in single-doped samples. Doping of the glass with both silver and copper ions leads to the increase of quantum yield by 2.7 times. The study was complemented by quantum chemical calculations using the time-dependent density functional theory. It was shown that fluorescence may be attributed to the formation of mixed Ag-Cu molecular clusters.

We present original types of III-nitride monocrystal microresonators with an inserted active quantum-sized region. Modelling of microresonator's modes allows us to select right parameters of a polarized quantum well (width, composition) in the way that excitation of its optical transitions would be selectively amplified by interaction with the resonator modes. Adjustment of a GaN nanocolumn resonator to an InGaN quantum well is performed.

In this paper spectral-luminescent, lasing, photochemical, and sensory characteristics of a number of Zn(II) and B(III) coordination complexes with dipyrrinates with different structures are presented. We have discussed relations of the structure of investigated compounds and formed solvates with their optical characteristics. The results showed that alkyl substituted dipyrrinates derivatives have excellent luminescent characteristics and demonstrated effective lasing upon excitation of Nd:YAG-laser. They can be used as active media for liquid tunable lasers. Zinc and boron fluoride complexes of dipyrrinates with heavy atoms in structure don't have fluorescence but have long-lived emission due to increased nonradiative intersystem processes in the excited state by the mechanism of a heavy atom. For solid samples based on halogenated complexes was found dependency of the long-lived emission intensity of the oxygen concentration in gas flow. The presence of line segment indicates the possibility of the use of these complexes as a basis for creation of optical sensors for oxygen. Moreover, results of a study of halogen-substituted aza-complexes under irradiation are presented. Such complexes are promising for the creating media for generation of singlet oxygen (¹O₂), which is important for photodynamic therapy in medicine and photocatalytic reactions in the industry.

In this article we investigate dielectric and magnetic properties of periodic metamaterials taking into account the so-called local field effect, caused by interaction between single particles the material consists of. We also consider the spatial dispersion effects. As a result, generalized Clausius-Mossotti techniques have been extended to the case of periodic metamaterials; permittivity tensor and permeability tensor were obtained.

By Raman scattering, luminescence, and IR-absorption spectroscopy multilayer nanoperiodic structures Ge/Al₂O₃ & GeO_x/Al₂O₃ have been investigated. The samples have been obtained by the physical evaporation; their properties have been varied by changing the layer thicknesses (2-20 nm) and annealing temperature (500-1000 °C). It is found that germanium nanocrystals are formed in the temperature range of 500-800 °C and exhibit intense size-depend photoluminescence at 1.2 eV and 1.8-2.0 eV.

An influence of thermal fluctuations of molecule's geometry on calculated electronic-absorption Vis/Uv spectra is considered. Paper presents the quantum chemical modeling of the electronic-absorption spectra for the collection of graphene samples (44, 56, 60, 68 atoms). The calculations were performed by time dependent density functional theory (TDDFT) method in combination with molecular dynamics (MD) simulation at T=300 K. The noticeable changing of spectra relative to single point TDDFT calculation was discovered for two of four structures. We associate achieved results with perturbation of hydrogen and carbon atoms on the edges of the structures. We believe that suggested methodology will be useful in application engineering researches of novel molecules and molecular complexes.

This article discusses the application of Raman spectroscopy for identification of wood species. Use of Raman spectroscopy allows increasing the certainty of determining the type of wood compared to the analysis of spectra of diffuse reflectance. Raman spectrums of different wood samples when irradiated by laser radiation are shown. Ways to improve the determination reliability of wood species due to the modernization of the identification technique are discussed. The stages of data processing, allowing carrying out correct further analysis are described.

We present cantilever-probe based scanning near-field microscopy (SNOM) studies of GaInP microdisks resonators (radii R=2 um and quality factors Q∼1000) with embedded InP quantum dots (QDs) emitting at ∼750 nm. Near-field photoluminescence spectroscopy in collection regime, using side excitation from micro-objective, was used for imaging of whispering-gallery modes (WGMs) with a spatial resolution below the light diffraction limit. Using collection-illumination regime we imaged the position of single InP/GaInP QDs in microdisk.

We present an analytical description of the process of spontaneous four-wave mixing in a cubic nonlinear fiber with linear losses. We consider the generation of photon pairs in the fiber when in the input of fiber is fed the pumping wave and single signal photon. The focus of attention is on three cases: when the signal photon propagates in the fiber without generating of biphotons; when the photon pair is generated; and when the photon is lost in the fiber. We also consider the cascade processes, but do not give them an analytical description because of their smallness. Description of the biphotons generation process we provide using the Schrodinger-type equation, and take into account the losses in the fiber through the introduction of the virtual beam splitters. We demonstrate the effectiveness of the generation of photon pairs through parametric processes.

In this paper, we present the results on study of formation regularities, morphology, composition and photoluminescence of porous silicon particles fabricated by the magnesiothermal reduction of different samples of biogenic silicon dioxide based on rice husk, bamboo husk and bamboo joints at 650 °C at argon atmosphere.

Food quality can be characterized by noninvasive techniques such as spectroscopy in the Near Infrared wavelength range. For example, 930 -1450 nm wavelength range can be used to detect diseases and differentiate between meat samples. Miniaturization of such NIR spectrometers is useful for quick and mobile characterization of food samples. Spectrometers can be miniaturized, without compromising the spectral resolution, using Fabry-Pérot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. The most commonly used mirrors in the design of FP filters are Distributed Bragg Reflections (DBRs) consisting of alternating high and low refractive index material pairs, due to their high reflectivity compared to metal mirrors. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer detector. Therefore, a bandpass filter is usually required to restrict wavelengths outside the stopband of the FP DBRs. Such bandpass filters are difficult to design and implement. Alternatively, high index contrast materials must be can be used to broaden the stopband width of the FP DBRs. In this work, Indium phosphide all air-gap filters are proposed in conjunction with InGaAs based detectors. The designed filter has a wide stopband covering the entire InGaAs detector sensitivity range. The filter can be tuned in the 950-1450 nm with single mode operation. The designed filter can hence be used for noninvasive meat quality control.

We report a design for creating a multilayer dielectric optical filters based on TiO₂ and SiO₂/MgF₂ alternating layers. We have selected Titanium dioxide (TiO₂) for high refractive index (2.5), Silicon dioxide (SiO₂) and Magnesium fluoride (MgF₂) as a low refractive index layer (1.45 & 1.37) respectively. Miniaturized visible spectrometers are useful for quick and mobile characterization of biological samples. Such devices can be fabricated by using Fabry-Perot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. Distributed Bragg Reflectors (DBRs) consisting of alternating high and low refractive index material pairs are the most commonly used mirrors in FP filters, due to their high reflectivity. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer range. Therefore a bandpass filters are required to restrict wavelength outside the stopband of the FP DBRs. The proposed filter shows a high quality with average transmission of 97.4% within the passbands and the transmission outside the passband is around 4%. Special attention has been given to keep the thickness of the filters within the economic limits. It can be suggested that these filters are exceptional choice for florescence imaging and Endoscope narrow band imaging.

We have analytically studied the evolution of optical vortices in a fibre resonator with two coils in the presence of an inter-coil coupling. We have shown that such a system can invert the orbital number of the incoming optical vortices if the resonance condition is fulfilled.

Transformation of zero-order Bessel beams into a second-order vortex beam in the process of propagation in a c-cut of lithium niobate LiNbO₃ crystal has been investigated experimentally. The possibility of controlling beam transformation by means of changing the curve radius of the illuminating beam is shown. The possibility of Bessel beam transforming by compact devices on the basis of thin c-cuts of uniaxial crystals with a diffraction mask formed on their surface is proved.

Information capacity of optoelectronic measuring systems significantly exceeds the volume of the others. The residual afterglow EOC creates additional uncertainty. There is a partial solution to the problem [1-2]. The work is dedicated to the enhancement of existing methods to fight the afterglow.

Here, the novel concept of asymmetric metal-dielectric (hybrid) nanoparticles is proposed. The experimental data and the results of numerical simulation of the optical properties of hybrid nanostructures are presented. The change of their optical response after fs- laser modification is shown. The possibility of manipulating Fano resonance in hybrid oligomers by the gold nanoparticles reshaping is demonstrated.

Simulation of Ti-indiffused waveguides on LiNbO₃ is described. The influence of diffusion conditions and technological parameters on the waveguide mode structure is considered. Boundaries of multimode, single-mode, and single-mode polarizing regimes of operation are defined.

We use radial Fractional Fourier transform to model vortex laser beams propagation in optical waveguides with parabolic dependence of the refractive index. To overcome calculation difficulties at distances proportional to a quarter of the period we use varied calculation step. Numerical results for vortex modes superposition propagation in a parabolic optical fiber show that the transverse beam structure can be changed significantly during the propagation. To provide stable transverse distribution input scale modes should be in accordance with fiber parameters.

Demand for efficient terahertz (THz) radiation detectors resulted in intensive study of the asymmetric carbon nanostructures as a possible solution for that problem. In this work, we systematically investigate the response of asymmetric carbon nanodevices to sub-terahertz radiation using different sensing elements: from dense carbon nanotube (CNT) network to individual CNT. We conclude that the detectors based on individual CNTs both semiconducting and quasi-metallic demonstrate much stronger response in sub-THz region than detectors based on disordered CNT networks at room temperature. We also demonstrate the possibility of using asymmetric detectors based on CNT for imaging in the THz range at room temperature. Further optimization of the device configuration may result in appearance of novel terahertz radiation detectors.

Silver-containing high-silica glasses were synthesized by an impregnation of the silica porous glasses (PGs) first with AgNO₃ aqueous solution (with or without the presence of the sensitizers, such as Cu(NO₃)₂ or Ce(NO₃)₃), next in the mixed halide salt (NH₄Cl, KBr, KI) solution. Then some part of the samples was sintered at the temperatures from 850 to 900°C up to closing of the pores. The structure of glasses was studied by UV-VIS-NIR and IR spectroscopy and X-ray diffraction (XRD) techniques. According to XRD data the silver-containing high-silica glasses contain the AgBr, AgI, Ag₃PO₄, (CuBr)_0.75(CuI)_0.25 phases. IR spectra confirmed B-O-B, Si- O-Si, P-O-P, O-P-O, O-B-O bonds, (PO₄)^3- and P-O^- groups in glasses.

We study the enhancement of the fluorescence an photoluminescence by large homogeneous arrays of plasmon coupled 5-8 nm Au and Ag nanoparticle separated by distances less than 10 nm. A red shift of the major "symmetric" plasmon mode near 780 nm, and additional "anti-symmetric" plasmon mode centered near 310 nm evidence the plasmon coupling in Au particle arrays. The systems were found to be effective in enhancement of the fluorescence/photoluminescence processes.

The advanced investigations of ϕ-conjugated organic molecule COANP sensitized with fullerenes have been revealed to consider this system as an affective medium for optical limiting and phase modulation. The special accent has been given to influence of the nanostructured relief at the interface on the spectral and photoconductive features.

Variation of absorption of terahertz radiation in lateral electric field was investigated in GaN epitaxial layers. Different behaviour of the absorption modulation in electric field was observed for radiation polarized along electric field and perpendicular to it. Joint analysis of optical and transport measurements let us obtain field dependencies of mobility, electron concentration and absorption cross-section. For terahertz radiation polarized perpendicular to the electric field, results are in accordance with Drude model of free electron absorption. Another polarization demonstrates significant deviation that is yet to be studied more thoroughly.

Spectra of the mid-infrared interband luminescence under interband optical pumping and impact ionization in strong electric fields are experimentally studied in the InAsSb epilayer and in the monocrystalline InSb in the temperature range from 10 K to 85 K. The recombination radiation anisotropy in InSb arising due to electron heating and drift in strong electric fields is observed.

The influence of the lateral electric field on the mid-infrared intersubband light absorption and near-infrared interband photoluminescence is experimentally investigated in tunnel-coupled GaAs/AlGaAs quantum wells. Absorption and emission modulation in lateral electric field are related to the electron heating and redistribution of hot electrons between the quantum well states resulting in variation of the space charge in the structure.

The main idea of this work was to determine the optimized parameters of E-beam lithography to obtain metal grating over dielectric thin film. This combination of metal/dielectric can provide high transmission spectrum of RGB colors. Different electric flux densities were used during E-beam writing and the best resolution and symmetric periodicity was obtained at 53 μC/cm² dose.

Spectral characteristics of InP/ZnS core/shell colloidal quantum dots of two different sizes (QD-1 and QD-2) were investigated. Absorption and luminescence spectra were analyzed for a series of solutions with a concentration range from 0.04 to 40 g/l. Energies of the optical transitions are evaluated. The obtained values of 2.60 eV (QD-1) and 2.38 eV (QD-2) correspond to the InP first excitonic transitions while 4.06 (QD-2) and 4.70 eV (QD-1, QD-2) are assumed to be caused by the ZnS shell absorption. Structures based on nanoporous anodic aluminum oxide (AAO) with the QDs were synthesized via an electrochemical oxidation and ultrasonic-assisted deposition. Chromaticity coordinates and correlated color temperatures for all phosphors under study were calculated. The fabrication possibilities of InP/ZnS@AAO nanostructures with tunable emission color (including the border of white region) were shown.

Hybrid nanophotonics based on metal-dielectric nanostructures unifies the advantages of plasmonics and all-dielectric nanophotonics providing strong localization of light, magnetic optical response and specifically designed scattering properties. Here, we propose a new method for optical properties tuning of hybrid dimer nanoantenas via laser-induced melting at the nanoscale. We demonstrate numerically that near- and farfield properties of a hybrid nanoantenna dramatically changes with fs-laser modification of Au particle. The results lay the groundwork for the fine-tuning of hybrid nanoantennas and can be applied for effective light manipulation at the nanoscale, as well as biomedical and energy applications.

We present time-resolved photoluminescence studies of epitaxial heterostructures with two arrays of Cd(Zn)Se/ZnSe quantum dots (QDs), which are formed by the successive insertion of CdSe fractional monolayers of different nominal thicknesses into a ZnSe matrix. Our data are suggestive of the appearance of effective channels of the energy transfer from the insertion comprising the array with smaller QDs, emitting at higher energy, towards the array with larger QDs, emitting at lower energy. The effect of dark excitons on characteristic times of radiative recombination is discussed.

The FDTD optical distribution model in the quasi single dimensional nanostructures is presented. The polar diagram is analyzed for nanowire structure with various diameters. The main conditions for the maximum output in vertical (0° and 180°), horizontal (90°) and leaky mode (30°, 60° and 165°) directions are discussed. Theoretical data show good agreement with experiments.

We report on Förster resonance energy transfer (FRET) in a dense array of II-VI epitaxial quantum dots (QDs). Besides FRET between the ground states of QDs of different sizes, we observe the energy transfer via the excited levels of large QDs which are in resonance with the ground levels of small QDs. The switching of dominant energy transfer mechanism, revealed by photoluminescence excitation spectroscopy, takes place at the energy controlled by the architecture of quantum levels in these arrays.

Silicon nanoparticles can possess magnetic Mie-resonant response in the visible and near infrared wavelength ranges. In this paper, we consider numerically the features of magnetic hot-spots realized inside silicon nanocylinders at the conditions of the optical magnetic resonances, and show that the intensity of the magnetic field inside nanoparticles with a coaxial through hole can be much stronger than the intensity of incident light waves.

The results of experiments that allow to evaluate changes of optical parameters of polymeric recording medium with diffusional amplification occurring during recording of information are presented. It is shown that phase characteristics of the sample compared to its initial state are observed during recording of information and in the post-exposure period, i.e. in a stable condition of the finished element. Quantitative estimates which can be used for planning conditions of holographic experiment during creating highly selective holographic optical elements (HOE) with given parameters are obtained.

Far field emission of optically pumped QD microdisk lasers with spherical Si nanoantenna placed on the top surface of microdisk is studied theoretically and experimentally. The interaction of the whispering gallery mode microdisk resonator with properly designed and positioned Si nanospheres results in improvement of light outcoupling and directed emission.

The numerical study of nanowaveguides containing ZO, AZO, GZO and other materials are studied in infrared range. The dispersion relation for the waveguides contained an arbitrary number of layers are solved numerically. The integral-differential equations in vector form of the electromagnetic waves propagation in nanowaveguides containing a finite width plasmon films are calculated by the Galerkin' method and the effective dielectric constants method. The opportunity of surface plasmon-polariton propagation with a large deceleration ratio are shown.

In the current work, the problem of UHF RFID passive tag sensitivity increase is considered. Tag sensitivity depends on HF signal rectifier efficiency and antenna-rectifier impedance matching. Possibility of RFID passive tag sensitivity increase up to 10 times by means of RTD use in HF signal rectifier in comparison with tags based on Schottky barrier diode is shown.

The response to electrical pulses of various parameters has been studied for the CMOS-compatible memristive nanostructures on the basis of silicon oxide demonstrating reproducible resistive switching. It is established that an increase in the amplitude or width of a single programming pulse is followed by the gradual decrease in the device resistivity. By applying periodic pulse sequences of different polarity it is possible to obtain both lower and higher resistance states. This adaptive behavior is analogous to synaptic plasticity and considered as one of the main conditions for the application of memristive devices in neuromorphic systems and synaptic electronics.

The results of studies of the long-term frequency stability as a function of the correlation coefficient for a tandem of two quantum magnetometers with laser pumping of ⁸⁷Rb in wall-coated vapour cell are represented. Measurement scheme includes a low-frequency self-generating magnetometer and a quantum microwave discriminator working at magnetic dipole transitions of radio-optical end state resonance. The difference of synchronously detected signals is processed to determine the Allan variance as a function of averaging time and correlation coefficient of signals. These parameters are essentially dependent both on the pumping light intensity and polarization and the intensity of radio fields that are produced in the working cell.

The electrocaloric response in ferroelectrics was experimentally investigated in nonequilibrium thermal conditions. The electrocaloric response reached 6 mK per one cycle polarization-depolarization of the ferroelectric sample. Computer modeling based on experimental data demonstrated the cooling capacity of multilayered structure at 25 W/cm³.

The results of development of InAlN/AlN/GaN heterostructures, grown on sapphire substrates by metal-organic chemical vapour deposition, and high electron mobility transistors (HEMTs) based on them are presented. The dependencies of the InAlN/AlN/GaN heterostructure properties on epitaxial growth conditions were investigated. The optimal indium content and InAlN barrier layer thicknesses of the heterostructures for HEMT s were determined. The possibility to improve the characteristics of HEMTs by in-situ passivation by Si₃N₄ thin protective layer deposited in the same epitaxial process was demonstrated. The InAlN/AlN/GaN heterostructure grown on sapphire substrate with diameter of 100 mm were obtained with sufficiently uniform distribution of sheet resistance. The HEMTs with saturation current of 1600 mA/mm and transconductance of 230 mS/mm are demonstrated.

We characterize superconducting antenna-coupled NbN hot-electron bolometer (HEB) for direct detection of THz radiation operating at a temperature of 9.0 K. At signal frequency of 2.5 THz, the measured value of the optical noise equivalent power is 2.0×10^-13 W-Hz^-0.5. The estimated value of the energy resolution is about 1.5 aJ. This value was confirmed in the experiment with pulsed 1.55-μm laser employed as a radiation source. The directly measured detector energy resolution is 2 aJ. The obtained risetime of pulses from the detector is 130 ps. This value was determined by the properties of the RF line. These characteristics make our detector a device-of-choice for a number of practical applications associated with detection of short THz pulses.

Paper describes the method of creating the sharp emitting tips on the surface of a field- emission cathode. The needle-shaped structures with a high aspect ratio on the glass-carbon plate are produced by means of nanosecond laser micromachining. The operations of laser scribing, milling and cleaning were applied for fabrication of the single- and multi-tip field-emission cathode. The special technique of laser rough and fine milling provided high tips with sharp and smooth apexes. As a result we obtained the tips with aspect ratio up to 600. The tests of cathodes showed that high density of current emission and a shorter technological route of production to be reached.

A micropump based on water electrolysis with a fast change of voltage polarity is presented. It is designed to demonstrate a new pumping principle with the gas termination time as short as 100 microseconds. The device consists of a working chamber with metallic electrodes, inlet and outlet diffusers, and channels for liquid. The chamber and the channels are filled with the electrolyte, which is the pumped liquid. The pump is fabricated on a glass substrate with the deposited metallic electrodes. The substrate is bonded with a polydimethylsiloxane structure containing the channels and the chamber. Design, fabrication procedure and preliminary testing of the device are described.

Model of the resistive switching in vertically aligned carbon nanotube (VA CNT) taking into account the processes of deformation, polarization and piezoelectric charge accumulation have been developed. Origin of hysteresis in VA CNT-based structure is described. Based on modeling results the VACNTs-based structure has been created. The ration resistance of high-resistance to low-resistance states of the VACNTs-based structure amounts 48. The correlation the modeling results with experimental studies is shown. The results can be used in the development nanoelectronics devices based on VA CNTs, including the nonvolatile resistive random-access memory.

A new highly sensitive device for analysis of gas compounds in terahertz frequency range based on the superconducting integrated receiver is being developed. Such receiver for spectral research of Earth atmosphere from balloon-borne instrument was developed earlier in Kotel'nikov Institute of Radio Engineering and Electronics and successfully operated during several flight missions. In this work, the laboratory setup for gas spectroscopy in the range of 450-700 GHz with the noise temperature below 150 K and spectral resolution better than 0.5 MHz is presented. First results of measurements of NH₃ and H₂O absorption spectra are obtained.

High temperature heating of experimental titanium samples using high frequency currents is studied. The velocity of heating is determined depending on the current value on the inductor. Experimental results are compared to the data of numerical modeling of heat transfer in metallic products. The peculiarities of the heating of cylindrical designs of two types: I (diameter - 3.75 mm, length - 10 mm) and II (diameter - 3.95 mm, length - 62 mm) implanted into the bone tissue were studied. The temperature of the constructional elements of different implant parts was calculated.

Methods of dispersion compensation in fiber-optic communication lines. A new proposed method of electronic dispersion compensation in the transmission of microwave signals through fiber-optic lines. Represents is proposed the results of experimental studies of this method.

The obtained results demonstrate that the improvement of nanomaterial arrangement in AlGaN/GaN HEMT structures quantitatively characterized with the use of a multifractal parameter (the degree of disorder) results in the increase at several times in the electron mobility values at 2DEG channel in HEMT structures and the reliability of HEMT parameters.

There is an investigation of the functional characteristics changes of a low noise amplifier under the influence of temperature changes with helping of a mathematical modelling in particular CAD AWRDE Microwave Office. The relative changes of the functional characteristics of electrical parameters of a low noise amplifier at the fixed frequency as a result of influence of the environment temperature are researching. As a result, temperature changes have a greater impact on the reflection coefficient than on the noise figure and gain.

Bipolar resistive switching phenomenon in the Au/Zr/ZrO₂-Y₂O₃/TiN/Ti memristive devices deposited by magnetron sputtering has been studied. The structure of devices and electrical measurements data for the temperature range from 77 to 490 K are analyzed. The stable switching is demonstrated at room temperature, but the decrease in the resistive switching performance at elevated temperatures is observed.

The experimental results of silicon carbide (SiC) drift step recovery diodes (DSRDs) temperature dependence of injection electroluminescence (IEL) spectra were presented. It was shown that in the forward current range I_f = 0,1...1 A the DSRD-dies temperature was raised from 327 K to 546 K correspondingly. While the short-wavelength maximum of IEL spectra - λ_max1 shifts from 392.4 to 402.1 nm and possesses dependence close to linear. On the basis of obtained calibration curves it is possible the non-contact temperature measuring of SiC-DSRDs by electroluminescence spectra at their operation in the generator of high voltage pulses.

In the present work the problems of technical diagnostics of RTD based on nanoscale multilayered AlGaAs heterostructures are being solved. The technique and the algorithms of RTD functionality region developing are being considered.

The two-layer polysilicon surface micromachining process flow of nanomechanical accelerometerincluded a high aspect-ratio etch step was presented.In the experiments we defined modes, and developed the technology of tunnelling gap formation using focused ion beam. The nanomechanical accelerometer crystals were fabricated by surface micromachining and focused ion beams.

In the experiments on the etched surface of gallium arsenide were performed. We studied the effect of BCl₃ gas flow rate on the thickness of the etched layer. GaAs etching rate was: 537,4 nm/min 28,7 nm/min 2,6 nm/min, the values of the flow rate of BCl₃ N_BCl3 - 15, 10, 5 cc/min, respectively. The effect of BCl₃ gas flow rate to the mean-square roughness of the etched surface. The influence of the anisotropy of the process on the geometry of the etched area. Revealed that the deflection angle for the samples treated with the working gas flow rate N_BCl3 - 15 cc/min in the [110] direction was α _[110] = 65,5° in direction [111] was α _[111] = 45,58°. For samples treated with the working gas flow rate N_BCl3 - 10 cc/min in the [110] direction was α _[110] = 20,94° in direction [111] was α _[111] = 11,37°. For samples treated with the working gas flow rate N_BCl3 - 5 cc/min in the [110] was α _[110] = 0,32° in direction [111] was α _[111] = 0,21°. The results can be used to produce discrete diodes, heterojunction devices, and other results.

The results of investigations of the quantum-size effects influence on selective properties of heterogeneous nanocatalysts are presents. As etalon exothermic reaction was used the reaction of atomic hydrogen recombination. The nanostructured Pd and Pt films on Teflon substrate were used as a samples of heterogeneous nanocatalysts. It was shown that for nanoparticles with various sizes the catalytic activity has the periodic dependence. It has been found that for certain sizes of nanoparticles their catalytic activity is less than that of Teflon substrate.

The results of experimental studies of porous silicon nanocomposite materials for future usage as an anode material of lithium-ion batteries are presented. Comparison between original and porous structures in terms of their qualitative and quantitative characteristics is given.

The influence of non-spherical nanopartides' shape on sedimentation process was studied. Six different shape of particles were considered. From proposed mathematical model it was shown that for non-spherical nanoparticles the perturbation of Z-component of velocity is slightly lower comparing to spherical particles.

The rate of thermal transitions in a kagome spin ice element is calculated using harmonic transition state theory for magnetic systems. Each element consists of six prolate magnetic islands. Minimum energy paths on the multidimensional energy surface are found to estimate activation energy. Vibrational frequencies are also calculated to estimate the rate of the various transitions. An overall transition rate between equivalent ground states is calculated by using the stationary state approximation including all possible transition paths. The resulting transition rate is in a good agreement with experimentally measured lifetime.

We derive an analytical expression for the crossover temperature corresponding to the transition from classical activation mechanism to temperature assisted quantum tunnelling in spin systems. The crossover temperature depends on the magnetic configuration and Hessian at the first order saddle point on the energy surface of the system. The theory is applied to several single spin models, including a system with four-fold anisotropy. Good agreement is obtained with experimental results for a molecular magnet containing Mn₄.

Calculations of the interaction between a magnetic tip of an atomic force microscope with a magnetic surface using the non-collinear extension of the Alexander-Anderson model are described. The mechanism and rate of thermally activated magnetic transitions in a cluster of atoms at the tip is investigated. The results are compared with experimental data and found to be in good agreement with measured lifetimes [R. Schmidt et. al., Phys. Rev. B 86, 174402 (2012).]. The results are also compared with previously reported density functional theory calculations.

In this study silicon dioxide - tin dioxide nanomaterials modified by fullerenol were obtained through sol-gel technology. The porousity changes caused by the fullerenols addition are discussed.

Metal-carbon nanosystems consisting of nanodimensional bimetallic particles of Fe- Co dispersed in a carbon matrix for the Fischer-Tropsch synthesis were studied. Prepared metal-carbon nanopowders samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It was shown formation of FeCo nanoparticles with body-centered cubic structures started at 400 °C. FeCo nanoparticles have spherical form, the mean size is 7 - 12 nm and uniform distribution in a carbon matrix. The metal-carbon nanosystem demonstrates a catalytic activity in the Fischer- Tropsch synthesis. The maximum yield of liquid hydrocabons C₅₊ was 92 g/m³ while the selectivity for the target product - 35%.

The possibility of using high-coercive of garnet films for thermo-magnetic recording is related with the presence of the metastable domain structure, which arises due to a significant mismatch of the lattice parameters of the film and the substrate. In the work the connection between facet crystal structure of elastically strained ferrite garnets films and the domain structure in them is established by methods of phase contrast and polarization microscopy.

Micro and nanostructuring of metals and alloys surfaces (Ti, Mo, Ni, T30K4) was considered by subnanocosecond laser radiation in stationary and dynamic mode in the liquid argon, ethanol and air. Depending of structures size on the samples surface from the energy density and the number of pulses were built. Non-periodic (NSS) and periodic (PSS) surface structures with periods about λ-λ/2 were obtained. PSS formation took place as at the target surface so at the NSS surface.

Photoluminescence (PL) negative circular polarization (NCP) dynamics of InP/InGaP quantum dots (QDs) was studied. Time resolved measurements of PL demonstrated that NCP vanishes, when transverse magnetic field is applied, while oscillations of polarization (that are typical for both low-dimensional and bulk materials) do not occur. Hole g-factor spread in the QD ensemble was supposed to be the most probable reason for such NCP magnetic field behavior. The dependence of NCP dynamics on the repetition period of excitation laser pulses was investigated. In case of fairly small repetition period (T = 13.3 ns) long living NCP (13.3 ns < t < 133 ns) was detected, what was ascribed to resident electron spin orientation, accumulated during many laser pulses. In that regime more than one luminescence polarization decay time exist.

We present the results of magnetic domain structure investigation by combination of atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM). Special hollow-pyramid AFM cantilevers with aperture was used. This combination allows us use same probe for both topography and domain structure visualization of Bi -substituted ferrite garnet films of micro- and nano-meter thickness. Samples were excited through aperture by tightly focused linearly polarized laser beam. Magneto-optical effect rotates polarization of transmitted light depend on domain orientation. Visualization of magnetic domains was performed by detecting cross polarized component of transmitted light. SNOM allows to obtain high resolution magnetic domain image and prevent sample from any disturbance by magnetic probe. Same area SNOM and MFM images are presented.

The goal of this work is experimental study of dielectric properties of polymer nanocomposites reinforced with multiwalled carbon nanotubes (MWCNTs) in alternating electric field in low frequency band of 0.01 Hz - 10 MHz. We investigated the influence, functionalization degree, aspect ratio, concentration of carbon nanotubes (CNTs) on dielectric properties of polymer sample. We also studied the dependence of dielectric properties on the polymerization temperature. The dependence of CNTs agglomeration on sample polymerization temperature and temperature's influence on conductivity has been shown. We conducted model calculation of percolation threshold and figured out its dependence on CNTs aspect ratio.

Titanium nitride coatings were deposited by reactive dc magnetron sputtering (dcMS) to protect Zr-1Nb alloys from hydrogen embrittlement. Dense titanium (Ti) interlayer was prepared between TiN_x protection film and a Zr substrate to improve thermal stability and adhesion between the TiN_x and the substrate at high temperatures. Hydrogen absorption of Zr- 1Nb with TiN_x and Ti/TiN_x at 623 K was reduced in comparison with uncoated Zr-1Nb. No peeling or cracks of Ti/TiN_x coatings is observed after thermal cycling up to 1073 K. The high temperature (1073 K) hydrogenation behaviour differs from the hydrogenation at lower temperature by increasing the amount of dissolved hydrogen in the β-phase of zirconium. The higher rate of hydrogen absorption by Zr-1Nb with TiN_x was observed due to the coating delamination as a result of differences in thermal expansion coefficients, while Ti/TiNx demonstrates the lower hydrogen absorption at 1073 K and good adhesion strength.

This article reports on technological possibilities of magnetron sputtering systems with solid-state and liquid-phase targets to deposition of aluminum films and its structure. The comparison of deposition rates of magnetron sputtering systems with direct current (DC), midfrequency (MF) and high power pulsed (HiPIMS) supplies is shown. The optical emission spectroscopy indicates a high component of target material ions in discharge gap only to HiPIMS technique. Al films are a (111)-line oriented in DC and MF power supply cases, for high power pulsed unit - aluminum films also have intense (220)-line. The dependence of grain sizes and sputtering technique parameters is obtained.

The aim of this investigation was to produce nickel hydroxide nanoparticles by chemical deposition method using different synthesis conditions such as temperature, pH and washing type. The phase composition was analyzed by X-ray diffractometer, which reveals that all the particles were β-Ni(OH)₂ phase with hexagonal lattice. XRD analysis also allowed determining the coherent scattering region size in order to compare it with particle size. Transmission electron microscopy showed that the Ni(OH)₂ particles have film forms with a thickness of about 1 nm. The surface area was determined using Brunauer-Emmett-Teller method and varies from 2 to 41 m²/gr.

Ceramics doped with chromium oxide were synthesized from alumina nanopowder at high heating and cooling rates. XRD analysis of the obtained samples shows that they consist mainly of Al₂O₃ α-phase. Photoluminescence (PL) spectra in the visible spectral region and thermoluminescence (TL) curves were measured. An effect of the dopant concentration on the intensity and shape of the PL bands as well as on the TL yield was found. Annealing of the quenching defects which emerged during the synthesis changed the PL spectra. The centers responsible for PL and TL in the synthesized ceramics were identified.

In the present study C-Co-Pd nanocomposites were prepared via Infrared annealing mediated method using precursor such as polyacrylonitrile (PAN), CoCl₂ • 6H₂O and PdCl₂. In addition the effect annealing temperatures such as 200, 250, 300, 400, 500, 600, 700, 800 and 900 °C on phase composition and structural characterization was analyzed using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Results reveals that the increase in temperature drastically influenced the phase and size of the C-Co-Pd nanocomposites.

The study focuses on combined spark alloying of titanium and titanium alloy surface and porous matrix structure oxidation. The metal-oxide coatings morphology is the result of melt drop transfer, heat treatment, and oxidation. The study establishes the influence of technological regimes of alloying and oxidation on morphological heterogeneity of metal- oxide system Ti-Ta-(Ti,Ta)_xO_y.

The objective of the present study is to produce C-Fe-Pd nanocomposites using pyrolyzed infrared (IR) radiation. The structural characterization was analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray fluorescence analysis. In addition, the size of metal nanocomposites as a function of the pyrolysis temperature, and its distribution within the carbon matrix is also characterized.

Parallel algorithm of partition function calculation of two-dimensional Ising model for systems with a finite number of spins was developed. Within a method of complete enumeration by using MPI technology with subsequent optimization of a parallel code time of calculations was reduced considerably. Partition function was calculated for systems of 16, 25, 36 Ising spins. Based on the obtained results, main thermodynamic and magnetic values dependences (such as heat capacity, magnetic susceptibility, mean square magnetization) for ferromagnetic and antiferromagnetic interactions was investigated. The analysis of a different configurations contribution showed, that states with the minimum energy have essential influence on dependences of thermodynamic values. Comparison with the results obtained by the Wang Landau algorithm was performed.

The results of experimental studies of magnetoresistance of polycrystalline materials (GeS)_1-x(CuAsS2)_x under high pressure (up to 50 GPa) are presented. The appearance of large negative magnetoresistance was found. The structure changing during applying high pressures was studied.

We present a theoretical investigation of the lateral shift of an infrared light beam reflected from a magnetic film deposited on a non-magnetic dielectric substrate, taking into account the linear magneto-electric interaction in the magnetic film. We use the stationary phase method to evaluate the lateral shift. It is shown that the magneto-electric coupling leads to a six-fold enhancement of the lateral shift amplitude of a p-(s-) polarized incident beam reflected into a s-(p-) polarized beam. A reversal of the magnetization in the film leads to a nonreciprocal sign change of the lateral shift.

The possibility of producing metallic tantalum nanopowders using electric explosion of Ta-wire was explored. The regimes of the electric explosion were determined which provided maximum level of energy brought into the wire. The basic properties of the obtained powders were examined using low-temperature nitrogen adsorption, atomic-emission spectrometry, as well as by means of transmission and scanning electron microscopes.

The results of investigation of thermal linear expansion for high temperature thermoelectric material nanostructured Si_0.8Ge_0.2P_0.022 n-type with maximum thermoelectric figure of merit Z = 0.98 10^-3 K are presented. Investigations were carried out by dilatometric method in the temperature range from 300 to 1220 K in dynamic heating and cooling regimes with using of infrared radiation source. Temperature dependence of thermal linear expansion coefficient (TLEC) was analyzed. The average value of TLEC for Si_0.8Ge_0.2P_0.022 was determined, which is equal to ∼5.9·10^-6 K^-1.

Process of plasma etching of CVD low-k dielectric was studied. We used CF₃Br low pressure ICP plasma for etching at cryo temperatures (-20°C — -100°C), pressures (5-20 mTorr) and RF bias with effective DC voltage 80-140 V. Refractive index of film and its thickness were measured by spectral ellipsometry. Ellipsometric porosimetry was employed to compare pore size distribution before and after etching of films. Measurements show increasing of etch rate increase with decreasing sample temperature.

We present the results of a complex experimental study of the electron transport phenomena in doped manganites of the SmMnO₃ system. The temperature dependences of the resistivity, thermopower, and Nernst coefficient were measured in different applied magnetic fields. Specific features of these dependences in different temperature ranges were revealed and discussed. Besides, all the studied transport coefficients demonstrate a similar behavior near the temperature of the magneto-ordered transition, T_c. The effects of the colossal magnetoresistance, colossal thermopower, and colossal Nernst coefficient were observed to be qualitatively analogous; all of them show a sharp rise at T ≈ T_c. It was also found that the value of the Nernst coefficient at temperatures below T_c depends strongly on the applied magnetic field thus demonstrating the anomalous behavior analogous to the one of the Hall coefficient.

We report the new system for manipulation of nanoobjects based on composite Ti₂NiCu/Pt nanotweezers with shape memory effect. The design consists of the bimetallic Ti₂NiCu/Pt shape memory nanotweezers placed on a tip of electrochemically etched tungsten needle. The semiconductor diode placed on the tip of the needle plays both role of resistive element of the heater and temperature sensor for feedback control loop closing. The device is compatible with existing positioning systems like OmniProbe^®, Kleindiek^®, etc. and may find numerous practical applications in various tasks of nanotechnology connected with 3D manipulation.

Nanomechanical system (NMS) based on amorphous carbon nanowhiskers localized on the top of tungsten tip were fabricated and investigated. The whiskers were grown in the scanning electron microscope (SEM) chamber using focused electron beam technique. The manipulation of SiO₂ and TiO₂ nanospheres was provided in SEM by means of dielectrophoretic force. Oscillation trajectories and amplitude-frequency characteristic of the oscillator were visualized at low pressure using a scanning electron microscope. The estimation of mass sensitivity of NMS was conducted.