Physics, Chemistry and Application of Nanostructures

The following sections are included:

• FOREWORD

• CONTENTS

Wide experimental evidence for non-uniform Ge concentration profiles in SiGe islands calls for the development of theoretical methods able to investigate the local distribution which allows for the best elastic-energy relaxation. Here, after reviewing a fast computational technique recently introduced in the literature [New J. Phys. 10, 083039 (2008)], we apply it to the study of intermixed three-dimensional pyramids of different aspect ratios. The local Ge distribution minimizing the elastic energy is found, emphasizing the driving force for Si enrichment close to the island base edges.

Contactless electroreflectance (CER) spectroscopy was applied to study the selected semiconductor nanostructures from the III-nitride and dilute nitride family of semiconductor materials. In the case of III-nitrides, the built-in electric field in AlGaN/GaN heterostructures have been determined by measuring the AlGaN-related Franz-Keldysh oscillation and analyzing its period. In the case of dilute nitrides, the optical transitions between the ground and excited states have been clearly observed in CER spectra of GaInNAsSb/GaAs quantum wells. The conduction band offset for these quantum wells has been found by comparing experimental data with theoretical calculations.

An InGaP/GaAs double heterojunction bipolar transistor (DHBT) was fabricated. Early effect observed in the normal operation of the DHBT suggests the interdiffusion or mixing of III and V elements at the GaAs-on-InGaP heterointerface. The analysis of both heterointerfaces in the atomic STM images confirms that the GaAs-on-InGaP heterointerface is rougher than the InGaP-on-GaAs heterointerface.

Here we present density-functional analyses of spin properties of hydrogen-terminated relaxed diamond C₂₇H₃₆, C₃₃H₃₆, C₃₆H₄₂, C₆₉H₈₄, C₈₄H₇₈ nanoclusters containing the NV^--center. Both ihfi and ahfi constants for various atoms in the clusters are calculated. The coupling constants for the C atoms belonging to the second and the third coordination shells around the NV^--center are about (±)8-12 MHz for ihfi and about (±)1-3MHz for ahfi while those for the forth shell are ~0.9 MHz for ihfi and ~(±)0.56-0.3 MHz for ahfi. These findings are in a good agreement with the available experimental data and show that rather distant ¹³C nuclear spins around NV^--center can be used as qubits to implement quantum register with an optical access.

Modeling of the atomic structure and spin properties of a NV^--center formed close to a (111) surface of nano-diamond has been carried out by using quantum-chemical PM3 and DFT methods. We consider the case where the nitrogen atom of the NV^--center is located in the near-subsurface atomic layer of a (111) facet. The relaxations of the surface atoms relative to their initial position are studied. The calculated spin densities for the considered clusters were compared with those ones for the clusters having the NV^--center in the bulk. It was confirmed that for the NV^--center in the bulk the spin density is located mainly on C atoms being the nearest neighbors to the vacancy. In the case of nanodiamonds there is a redistribution of the spin density resulting in its major allocation at the three C atoms being the nearest neighbors to the N atom and forming just the first atomic layer of the (111) surface.

An interaction of travelling waves of classic light with 1D-chain of coupled quantum dots (QDs) in strong coupling regime has been theoretically considered. The effect of space propagation of Rabi oscillations in the form of travelling waves and wave packets has been predicted. Physical interpretation of the effect has been given, principles of its experimental observation are discussed.

Electron transport through a triple-terminal Aharonov-Bohm interferometer is theoretically studied. By applying a local Rashba interaction to a quantum dot, we find that spin polarization and spin separation can be simultaneously realized with the adjustment of quantum dot levels, i.e., an incident electron from one terminal can select a specific terminal to depart from the quantum dots according to its spin state.

We have performed ab initio calculations of electronic band structures of nonhydrogenated silicon nanowires in the <001>, <011>, <111> and <112> orientations. Our results clearly indicate that silicon nanowires with the <001>, <111> and <112> axes have turned out to be metallic, while the one with the <011> axis displays the semiconducting behavior.

This work focuses on the behaviour of an intrinsically fractal, binary chain, showing a rich structure in its vibrational spectrum, clearly distinct from that of conventional quasi-periodic chains. Furthermore, an approximate solution is given in the weak-coupling limit and the relationship with fractal chains, the discrete analogue of fractal strings, is emphasised.

Phonon-assisted tunneling model is applied for explication of temperature-dependent I-V characteristics measured by other authors for (Bi_1-xSb_x)₂Te₃ and ZnSnO₃ nanowires. The fit of experimental data of the current dependence on applied voltage measured at different temperatures with two theories of phonon-assisted tunnelling explains well the variation of I-V curves with temperature as well as the temperature dependence of conductivity of nanowire.

It is shown that in the existing theory of the resonance (phononless) AC hopping conductivity, the one-particle density of states with a Coulomb gap generally cannot be used in the calculation of the resonance AC conductivity. In a wide frequency range, the correlations between the one-electron energies of the active pairs should be taken into account predicting a slightly sublinear frequency behavior of the conductivity in the entire frequency range of interest rather than the crossover from linear to quadratic frequency dependence.

The paper describes the application of singular-value decomposition method for resolution estimation and resolution enhancement in near-field optics with focus at scanning near-field microscopy. Analysis of general properties of singular functions and associated singular values is presented.

According to the string model, the hole pairs in cuprates tend to segregate into nanosized bosonic stripes (NBS), whose hierarchy on an energy scale is defined by their discrete width. It is argued that the concept of NBS can clarify controversial issues about the puzzling origin of extraordinary pseudogap manifestations observed by various techniques in electronic properties of underdoped cuprates and related transition-metal oxides.

Carrier relaxation due to both optical and nonradiative intraband transitions in silicon quantum dots (QDs) in SiO₂ matrix is considered. Interaction of confined holes with optical phonons is studied. The Huang–Rhys factor governing intraband multiphonon transitions induced by this interaction is calculated. The new mechanism of nonradiative relaxation based on the interaction with local vibrations in polar glass is studied for electrons confined in Si QDs.

The technology of nanostructured silicon built-in an anodic alumina films has been developed. The films thickness was varied from 20 to 140 nm. Structural properties and photovoltage phenomena are investigated in these films. Fast and slow components have been observed in photovoltage transients assigned to intra- and interparticle transport of excess photogenerated carriers, respectively. The linear dependence of the photovoltage amplitude on the film thickness gives an evidence that silicon nanoparticles form an interconnected network inside the dielectric matrix. Applications of nanostructured silicon built-in anodic alumina films are discussed.

SiO₂ layers pre-implanted with 140 keV Si ions, and those with embedded Si nanocrystals (Si-ncs) have been irradiated with 130 MeV Xe ions. HREM and photoluminescence spectroscopy were used for the characterizations. In the Si-implanted layers HREM revealed the 3-4 nm-size dark spots, whose number and size grew with increase in Xe ion dose. Photoluminescence showed the presence of two bands – at ~780 nm and at ~670 nm. The intensity and position of the bands depended on the dose. Changes of the spectra and the results of passivation were interpreted as transformation of Si-ncs (~780 nm) into damaged Si-ncs (~670 nm) and vice versa. It is concluded, that electronic losses are responsible for the formation of new Si-ncs, whereas elastic losses introduce the defects.

We have studied alternating germanium-silicon-silicon oxide layers of 41 nm thickness grown on Si substrates by plasma enhanced chemically vapor deposition. The compositions of the grown films were determined by X-ray photoelectron spectroscopy. The films were annealed at temperatures varying from 700 to 950 °C for 7.5 minutes under nitrogen atmosphere. High resolution cross section TEM images, electron diffraction and electron energy-loss spectroscopy as well as energy-dispersive X-ray analysis (EDAX) confirm presence of Ge nanocrystals in each layer. The effect of annealing on the Ge nanocrystal formation in multilayers was investigated by Raman spectroscopy and TEM.

The Raman scattering in Si nanocrystals non-unifoimly distributed in SiO₂ (fused quartz) and Al₂O₃ (sapphire) matrices was studied. The mean diameter of the nanocrystals in SiO₂ is determined that is consistent with electron microscopy data. In case of nanocrystals embedded in Al₂O₃ Raman shifts indicate existence of a compressive stress that suppress Si nanocrystal photoluminescence.

It is shown that heat treatments cause remarkable structural instability in hydrogenated nanostructures made of alternating 3 nm thick layers of a-Si and a-Ge deposited by sputtering. Upon annealing surface bumps are formed. Their size and density increase with increasing H content. They appear due to the presence of H bubbles in the samples, which even blow up for the highest H content. The H bubbles are produced by accumulation of H₂ molecules made possible by the break of the Si-H and Ge-H bonds driven by energy supplied by the heat treatment and the recombination of thermally generated carriers.

In this paper, the investigation of the process of Ge nanoclusters formation during the deposition of Ge-doped poly-Si films is described.

Solid phase (SPE) and molecular beam (MBE) epitaxy of silicon atop nanosize Mg₂Si islands and 2D Mg₂Si layers with Si(111)2/3√3-R30° structures on Si(111) substrates was studied. It was established that the Si crystal structure is improved during SPE at a temperature increase from 550°C to 750°C, but Mg₂Si decays and desorbs from the surface. At MBE (V_Si = 0.17 nm/min at 150°C) of Si atop a 2D Mg₂Si layer the ordered embedding of the latter is observed, but an additional annealing at 550°C results in improving of crystal quality of the silicon layer.

Semiconducting CrSi₂ nanocrystallites (NCs) were grown by reactive deposition epitaxy (RDE) of 0.6 nm Cr at 500, 550 and 600 °C. The NCs were covered by epitaxial silicon at 700 °C with different thickness. It was observed that CrSi₂ is localized near the surface in the form of 20 nm 2D nanoislands and 40-80 nm 3D NCs. The 2D nanoisland concentration is found to be reduced by the Si cap growth, while the large 3D NCs appear at the depth of Cr deposition and they also appear at the surface.

The morphology and optical properties of Si samples implanted by Fe, Cr and Mg ions have been studied before and after pulsed annealing by laser and ion beams. Ultrahigh vacuum cleaning and epitaxial growth of Si films with thickness up to 500 nm have been carried out for Si with Fe and Cr silicide nanocrystallites. Optimum conditions of pulsed treatments have been determined for all samples.

The results of quantum chemical modeling of growth, structural stability and electronic structure of silicon nanotubes are presented. Atomic diffusion in nanotubes is also studied. A synthesis of perfect silicon nanotubes was demonstrated to be suppressed by formation, on initial stages of growth, of mixed structures. The effect of external pressure on the growth of silicon nanotubes was modeled.

The theory of the saturable absorption effect in single-wall carbon nanotubes has been elaborated. The kinetic equations for density matrix of π-electrons in a single-wall carbon nanotube have been formulated and solved analytically within the rotating wave approximation. The dependence of the carbon nanotube absorption coefficient on the driving field intensity has been shown to be different from the absorption coefficient behavior predicted for the case of two level systems.

The existence of clusters of single-wall carbon nanotubes (SWNTs) in solvents is discussed. The bundlet model for clusters describes the distribution function of clusters by size. The phenomena have an explanation in the bundlet model, in which the free energy of an SWNT is combined from two components: a volume one, proportional to the number of molecules n in a cluster, and a surface one proportional to n^1/2.

The structure and properties of C₂₀@(8, 8) CNT system are explored by quantum chemical and molecular mechanic calculations. The change of the barrier for relative motion of fullerene along the carbon nanotube axis at the Peierls transition is found. The changes of dynamical behavior of the system C₂₀@(8, 8) CNT at the transition are discussed.

The effect of slowing down of electromagnetic waves in a multi-wall carbon nanotube (MWCNT) is considered. The possibility of significant decrease of the wave phase velocity in MWCNT as compared with a single-wall nanotube (SWCNT) is demonstrated.

We report on polarization sensitive microphotoluminescence studies of wurtzite type GaN/AIN quantum dots grown on (0001) sapphire substrates by molecular beam epitaxy. Typical linearly polarization degree of photoluminescence is about 0.06. Photoluminescence intensity of some particular samples decreases over time under continuous-wave excitation on a timescale of minutes. Emission of such samples is linearly polarized with polarization degree of about 0.15. Possible reasons of the observed behavior are discussed.

Double band-emitting ZnSe:Mn-ZnS colloidal quantum dots solubilized with various mercaptoacids demonstrate the different response in the emission intensity to pH level in a solution. In the case of mercaptoacetic acid both the excitonic and Mn emission bands increase the intensity with increased pH. For mercaptoundecanoic acid only the excitonic emission band was found to be sensitive to pH. The mechanism proposed is based on the competition between three recombination channels of an excited exciton: direct radiative recombination and energy transfer to Mn ion.

We studied electric field effects on optical properties of CdSe/ZnS nanorods integrated in thin films sandwiched between transparent electrodes. It was demonstrated that P-polarized component of the photoluminescence of CdSe/ZnS nanorods is quenched stronger by external electric field than the S-polarized component. Quantum dots are more sensitive to external electric field than the nanorods. A mechanism of external electric field influence on the luminescence spectrum of semiconductor nanorods is discussed.

PbS nanoparticles with features of quantum dots (QDs) have been fabricated in boron-silicate glass matrix. Their mean diameter was found to be in the range of 3.4–8.2 nm from the optical spectroscopy data due to their explicit quantum confinement effect. The particle size and position of the absorption bands can be controlled through the regimes of thermal treatment of the glasses. SAXS technique showed near to monodisperse size-distribution of QDs and possible ordering within the glass matrix.

Optical waveguides for transporting light at the wavelength of 1 µm have been prepared in glasses doped with PbS quantum dots of 4 nm in mean size. Two methods of fabrication were applied: ion exchange technique (planar waveguides) and direct femtosecond writing (channel waveguides). The both techniques allowed light guiding.

The photoluminescence quenching of semiconductor CdSe/ZnS quantum dots (QDs) caused by surfacely attached porphyrins increases with QDs size decrease. "Porphyrin-QD" interaction induces a pertubation of the excitonic wave function leading to a net charge localisation of the electron-hole pair accompanied by an increase of radiationless decay rates being proportional to the calculated radial probability of the confined exciton wave function at QD surface.

The directed surface passivation of semiconductor CdSe quantum dots (QD) by quinone and its halogen substituted derivatives with increasing electron accepting abilities has been realized via the reversible non-covalent self-assembly interaction of organic and inorganic subunits. The formation of "QD-quinone" composites is manifested in strong photoluminescence (PL) quenching (intensity decrease and decay shortening). It was shown that for QDs capped with quinones, PL quenching is due to the photoinduced electron transfer (PET) and strongly depends on redox properties of quinones as well as on Gibbs' free energy ΔG⁰.

One-dimensional colloidal photonic crystals reported here are linear close packed assemblies of monodisperse polystyrene globules with sizes in the micron range. Luminescence of these structures reveals co-existence of localized whispering gallery modes (WGMs) and propagating nanojet-induced modes (NIMs). The latter modes result from the optical coupling of globules acting as micro-lenses, which periodically focus propagating light into photonic nanojets.

Laser properties of InGaN/GaN heterostructures grown on silicon substrates were investigated under optical pumping by laser pulses of femtosecond duration. Gain spectra in the structures investigated were examined using the method of variable excitation stripe length. It was shown that laser spectra as well as optical gain spectra inside the structure are broadened considerably. Reasons causing spectra broadening are discussed.

Using the exciton trap (polymethine dye DiD) the efficiency of exciton energy transport in luminescent molecular nanoclusters (J-aggregates) of polymethine dye amphi-PIC has been investigated. It has been shown that 50% of J-aggregates luminescence is quenched at the ratio amphi-PIC/DiD = 120, which points to the effective energy transport in the J-aggregates as compared with J-aggregates of other dyes. An incorporation of surfactant CPB into the J-aggregate chain leads to increasing the energy transport efficiency due to a suppression of localization processes in J-aggregates. In presence of CPB 50% of J-aggregates luminescence is quenched at the ratio amphi-PIC/DiD = 160.

Simultaneous account for local field and local density of photon states enhancements in close proximity to a silver ellipsoidal nanoparticle is found to provide up to 10¹⁴-fold Raman scattering cross-section rise up. A model of the so-called "hot points" in surface enhanced spectroscopy has been elaborated as local areas with high Q-factor at incident and scattered (emitted) light frequencies. Further experiments are proposed towards verification of the model in terms of transient Raman experiments to clarify incident field enhancement and scanning near-field optical mapping of local density of photon states.

Enhancement and quenching of the secondary emission of poly-L-lysine stained by eosin and hematoxylin immobilized between two plasmonic silver films (PSFs) are reported. Optical engineering of PSF involving the turning of localized plasmon (LP) band in resonance to dyes absorption and fluorescence bands is discussed as the way to successful PSF application in clinical assays.

We present experimental results on emission dynamics of silver nanoparticles (NPs) deposited on a glass substrate. Upon continuous-wave excitation at 488 nm, Ag NPs emit light in the yellow, orange, and red spectral ranges. This emission is intermittent, consisting of distinct on- and off-periods (blinking) with on- and off-times showing power-law distributions. We find that subsequent on- and off-times of Ag NP emission are not independent, exhibiting correlation that extends for a few tens of blinking events, thus indicating the presence of memory in the process governing the NP blinking dynamics. To the best of our knowledge, this is the first observation of the presence of memory in blinking dynamics of metal nanoparticles.

We report on application of Ag nanoparticles in high sensitive surface-enhanced Raman spectroscopy to detect low quantity of art pigments.

Strong enhancement of light absorption over the spectral range of the copper localized surface plasmon resonance has been observed at two-layer planar systems of copper and silver nanoparticles made with the use of successive vacuum evaporation. The result obtained is treated with taking into account strong near-field coupling at a close-packed array of silver and copper nanoparticles.

Iron, nickel and cobalt were selected as catalysts for the generation of nanocarbons in the present study. Structural peculiarities: shape, orientation, defects of catalyst particles and fillings of as-prepared specimens were studied using HRTEM analysis. It was shown that orientations of metal particles, located inside carbon nanotubes (nanofibers), along the longitudinal axis for fcc and bcc crystal lattices can be characterized by the same directions: [100], [110], [111] and [112]. It was found that fcc-particles of all three metals often contain twins. The obtained results are discussed in the framework of the epitaxial growth model and deformation processes inside nanotubes.

A thermodynamic model for the molecular beam epitaxy of strained quaternary III–III'–V–V' layers on a lattice-mismatch substrate is developed. On the basis of the model, the In incorporation in growing GaInNAs/GaAs nanolayers is analyzed. The In concentration is calculated versus such growth parameters as the growth temperature, the growth rate, the arsenic incident flux, and the In concentration in the layer.

We examined pore formation in amorphous silicon nitride by means of swift heavy ion irradiation followed by chemical etching of latent tracks in Si₃N₄ matrix. The samples were irradiated with 180 MeV ions up to the fluence of 2 × 10⁸ cm^-2. Afterwards the targets were etched in the dilute solution of hydrofluoric acid. Scanning electron microscopy and atomic force microscopy were used to probe the processed samples in order to observe etched tracks and measure their surface diameters. The limited etching efficiency and significant difference of surface pore diameters allowed to suggest that the ion tracks were discontinuous in the studied irradiation conditions.

Two types of composite films on the basis of π-conjugated polymers, poly-(N-epoxypropyl)carbazole (PEPC) and poly-(N-vinyl)carbazole (PVC), and metal nanoparticles have been fabricated. The sizes of nanoparticles depend on type of the polymer matrix. Complex testing of the obtained materials has shown that conductivity and optical effects are more evident in the case of PEPC films.

Terbium-doped oxide corresponding to chemical formula Tb_0.15Y_2.85Al₅O₁₂ was fabricated from the diluted nitrates of Tb, Al and Y on monocrystalline silicon and in porous anodic alumina. Unlike to our earlier presented works with titania or alumina xerogel the proposed technology does not allow fabrication of YAG xerogel monolith, whereas only occasional clusters are observed inside the mesoscopic channels of porous anodic alumina. Strong PL bands within the range of 480-640 nm corresponding to ⁵D₄-⁷F_j(j = 3, 4, 5, 6) transitions of Tb⁺³ ions appear after annealing of the samples at 700°C. Strong enhancement of these PL bands with the well-resolved Stark splitting at room temperature occurs after annealing of the films at 900°C.

We report on a method for development of dichromatic luminescent images on the basis of porous anodic alumina grown in several electrolytes with the use of europium deposition from alcoholic solution of lanthanide nitrates.

Kinetics of erbium photoluminescence was investigated at the wavelength of 1.54 µm in the films of amorphous hydrogenised silicon doped with erbium and oxygen. The results of the study showed that the optically active erbium was located both in the semiconductor matrix of amorphous silicon and in the dielectric nanocrystals of erbium silicates that formed at large oxygen concentrations in the gas discharge of the magnetron chamber. The mechanism of erbium excitation in this heterogeneous system was discussed. The external quantum yield of erbium photoluminescence from the films measured at room temperature amounts to approximately 0.5%.

Silicon oxide nanostructures are prepared by local anodic oxidation on dodecyl-terminated silicon. Cationic dye molecules (Rhodamin 6G) bound electrostatically to the generated nanostructures are investigated by optical methods. Quenching of luminescence due to the interaction of the excited states with silicon can be found. The luminescence signal is attributed to monomeric Rh6G molecules with a slight blue shift of the emission due to the changed chemical environment.

A facile method to fabricate a porous alumina layer at high forming current densities has been developed. This method allows to carry an anodic process of aluminium film dipping into the electrolyte in meniscal region with forming current density up to 1500 mA/cm² and anodising rate up to 70 µm/min. The structure of the porous alumina formed has been found to be selforganized nanotube cells for anodizing current densities more than 100 mA/cm².

Nb thin films have been deposited on porous silicon (PS) substrates. The PS templates consists of a short-range order matrix of pores with mean diameter of 10 nm and mean interpore distance of 40 nm, which act as an array of artificial pinning centers. Commensurability effects between the Abrikosov vortex lattice and the artificial one were investigated by transport measurements.

Overdoped superconducting Nd_2-xCe_xCuO_4-δ (NCCO) (x = 0.17) thin films have been fabricated by using a planar dc sputtering technique. Current-voltage (I-V) characteristics and critical current densities J_c have been measured as function of the perpendicular magnetic field at different temperatures. Films with critical temperatures around 10 K and critical current densities above 10⁸ A/m² at T = 2.1 K have been obtained.

Results of investigations of vanadium dioxide thin films obtained by the electron-beam evaporation method are considered. Structural and surface morphology of VO_x thin films on silicon substrates are presented. Analysis of electrical characteristics of the studied samples is given. A hysteresis of temperature dependences of capacitance and resistance, as well as the phase transition at 58 °C are obtained.

The nanocomposite film of ladder-type methyl substituted poly-para-phenylene and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinilene] was investigated using the photoassisted scanning tunneling microscopy. The photoSTM images allow to discern the difference between two components in the nanocomposite. The mechanisms of the formation of photoassisted scanning tunneling microscopy images are discussed.

The effect of the initial particles size (400 nm, 5 µm and 50 µm) and sintering temperature (800-1900°C) on densification of TiB₂ powder under the pressure of 4 GPa has been investigated. The results concerned with microhardness and modulus of elasticity of sintered samples are reported. It has been shown that the powder with mean particles size of 400 nm demonstrates the best densification intensity under low sintering temperatures. Samples sintered from powder with mean particles size of 5 µm have the highest density (about 99%) and modulus of elasticity (about 500 GPa). The samples sintered from powder with mean particles size of 50 µm have the highest microhardness (about 37 GPa).

This paper reports on preparation of the optically transparent Ge-Zr-O nanosystem by means of the inorganic sol-gel technique and demonstrates the first observation of its visible photoluminescence (PL) under the thermal treatment in air. This PL can be caused by the structural defects spontaneously formed in the system during its synthesis.

A scanning probe microscopy (SPM) study of (Co_0.4Fe_0.4Zr_0.10)_x(Al₂O₃)_1-x nanocomposite films has been carried out. Correlations between SPM images and measured structural, magnetic and electric properties were observed. SPM images confirm the presence of metallic 4-10 nm nanoparticles, embedded in the alumina matrix near the percolation threshold. The distribution of SPM contrast points to the presence of great agglomerates ("clouds") of metallic nanoparticles with sizes of 100-500 nm.

A technology of Sr₂FeMoO_6±δ (SFMO) nanosized films deposition by ion-beam sputtering is described. Optimization of deposition conditions on formation of structurally-perfect SFMO double perovskite films is presented. Several problems arise with the use of the ion-beam sputtering method concerning the films inhomogeneity, the presence of multiple phases and Fe_Mo and Mo_Fe antistructural defects. It is shown that they are solved by means of complex selection of parameters: substrate temperature, deposition rate and subsequent thermal processing.

SOI-like structures produced by nitrogen implantation (N₂⁺ doses, D = 5 × 10¹⁶ - 8.5 × 10¹⁷ cm^-2, energy 140 keV) into Czochralski grown silicon (Cz-Si) and subsequent processing of Cz-Si:N at high temperature (HT) up to 1520 K under atmospheric or enhanced (up to 1.1 GPa) hydrostatic pressure (HP) were investigated. The main effects of the HT-HP treatment are the following: a decreased Si/SiN_x interface roughness and improved uniformity of the layer thickness, a decreased concentration and dimensions of defects at the top silicon layer and the substrate, a suppressed formation of exfoliation defects in the top silicon layer, a decreased size of silicon nanocrystals at the Si/SiN_x interface and nitride nanocrystals within amorphous SiN.

Some ideas and experimental results related to the effect of switching magnetic domain walls in three- and four-arm nanostructures, fabricated from ferromagnetic (Ga,Mn)As layers, are presented. Changes in electrical resistance of those structures, accompanying switching, could be used in spintronic devices.

CoFeZr-Al₂O₃ nanocoposite films of 3-5 µm thickness, containing metallic alloy nanoparticles embedded into dielectric alumina matrix have been deposited using magnetron sputtering of a composite target in Ar and Ar + N₂ gas ambient. A behavior of complex high-frequency permeability on content of the metallic phase depends critically on sputtering atmosphere. Nitrogen in the sputtering chamber is shown to retain the super-paramagnetic state of the nanocomposites.

Ferromagnetic Fe_1-xNi_x(P) (x=24-65 at.%.) columns have been chemically deposited into porous polycarbonate membranes with pore diameters of 0.1-4 μm. The morphological characterization by TEM reveals the shape features in synthesized columns. Their magnetic perpendicular anisotropy due to the shape anisotropy of columns was observed. The dependence of macroscopic anisotropy on pore diameter and Ni content is analyzed. Approach to magnetic saturation curves and exchange constant of nanocrystalline Fe_1-xNi_x(P) columns deposited into porous polycarbonate matrix are investigated.

Structure and magnetic properties of Co nanoparticles in the high-porous amorphous carbon matrix are presented. The average size of cobalt particles is 20 nm. The Co nanoparticles are ferromagnetic and characterized by the local magnetic anisotropy fields H_a = 10 kOe. The material consists fcc and hcp Co phases and highly defective phase with high concentration of stacking faults. There are no variations observed in the line shape of the NMR spectrum of Co particles at different temperatures. This implies that there are no polymorphous transformations inside Co particles with temperature.

Investigation of the nanostructured Co-Cu alloy formation process during mechanical alloying was carried out with composite particles representing a Co–P alloy core covered with a copper shell. Magnetic and structural properties have been investigated by electron microscopy, X-ray diffraction, magnetic measurements and NMR-spectroscopy. The metastable Co-Cu solid solution is composed of at least two magnetic phases: ferromagnetic solid solution (formed after milling for 2–3 h) and superparamagnetic particles. The blocking temperature T_B and the number of superparamagnetic particles were estimated from M(T) curves near liquid helium temperature. The magnetic constants (magnetization, anisotropy field) for the composite particle powders milled at different times were obtained.

We present the experimental results on magnetorefractive effect in ferromagnetic metal-metal, and metal-insulator multilayer films of different compositions and different types of magnetoresistive effects. The magnetorefractive effect can be used as a noncontact probe of magnetoresistive properties in thin magnetic films through investigations of the field-dependent reflection behavior in the IR region.

Manganese-doped CdS nanoparticles were synthesized in an aqueous solution by using polyvinylalcohol (PVA) as the capping reagent. The nanoparticles were characterized by TEM, EPR and photoluminescence spectroscopy. In the photoluminescence spectra there was a band assigned to internal transitions in Mn ions. Additional confirmation of the presence of Mn inside nanoparticles is obtained by registration of typical EPR signal of Mn²⁺ ions in CdS:Mn nanoparticles embedded in a PVA matrix.

The Au-Fe multilayer nanostructures are studied by the femtosecond pump-probe using Ti:Sapphire laser pulses at the wavelength of 800 nm. A new scheme of pumping from the back side of the film was introduced, providing the injection of the spin-polarized electrons into the diamagnetic Au layer. The magnetic contrast of the Au surface detected by the second harmonic generation (SHG) technique appeared to be as large as several percent, while the reversal magnetization of the medium was observed after relaxation. The even-in magnetization second harmonic (SH) component dropdown followed by the relaxation was also observed, with the amplitude of the dropdown being proportional to the pump fluence.

An effect of external factors on giant magnetoresistance (GMR) for asymmetric layer structure metal/polymer/non-magnetic metal was investigated. The magnetostriction, galvanomagnetic effects and instability of contacts are not the reasons for GMR appearance. The conclusion on the injective nature of the GMR effect was drawn.

Magnetic and nuclear gamma resonance (NGR) parameters of EuO:Fe composites are studied. Their properties really meet the requirements imposed on the use of them as spin injectors in semiconductor spin-electronic structures capable of operating under normal conditions at room temperatures.

Local Fe states (using Mössbauer spectroscopy) and thermal expansion coefficient in FeIn₂S₄ single crystals grown by the directional crystallization of the melt (vertical Bridgman growth) have been studied.

An influence of a weak magnetic field on the evolution of porous silicon surface species during ageing in air and porous silicon photoluminescence is studied. Magnetic field retards the process of Si surface oxidation and stimulates a breakage of Si-H_x bonds at the porous silicon surface. It also affects bond energy in silicon complexes with water molecules.

Trends of transformation of non-magnetic BeGeAs₂ compound upon doping with 3d-elements (V, Cr, Mn, Fe) were investigated using ab initio pseudopotertial method. Impurity was considered in II or IV group sites. All dopants lead to an appearance of ferromagnetism with the exception of manganese in II site and vanadium in IV site. In the case of Fe the magnetic moments were found to depend strongly on the distance between substituting atoms and to differ considerably in ferromagnetic (FM) and antiferromagnetic (AFM) states. The spin polarization of doped compounds in stable states was evaluated.

The charge carrier transport model of the CoFe/MgO/CoFe nanostructure taking into account the Schottky barrier and interface charge was developed. TMR and I-V characteristics were calculated on the basis of experimental data and modeled for different parameters of the nanostructure. Estimates of TMR are realized through the variation of height of the effective barrier for spin-up and spin-down electrons. Growth of TMR is 0.18, 0.40 and 0.55 when the energy difference between barriers is 0.02 eV, 0.05 eV and 0.10 eV, respectively.

Dielectric breakdown in nanosize gate stack of state-of-the-art Si nanoelectronic devices has been one of the key reliability concerns. We present the recent development in using physical analysis techniques to decode the nature of the breakdown path or more commonly called as percolation path in ultrathin SiON and HfO₂-based gate materials. The influence and extent of the dielectric breakdown to the surrounding material and structural modification are reviewed. Our results suggest that if the material and microstructural changes can be controlled upon breakdown, the conductance in the breakdown path in the broken dielectrics can still be maintained in a very low leakage mode, resulting in prolonged and good charge coupling from the gate to the channel for reducing transistor degradation.

The synthesis and characterization of monodisperse SnS nanocrystals and the means by which shape control may be effected through judiciously varying the ratio of ligands in the reaction mixture are reported. The nanoparticles may subsequently be linked to conducting transparent substrates, and their optoelectronic responses are investigated. A photocurrent in the range of 6-8 nA cm^-2 was recorded for sub-monolayer amounts of the materials on ITO.

The synthesis and photochemical treatment of Zn_1-xCd_xSe nanocrystals (NCs) capped with thioglycolic acid (TGA) were investigated. A well reproducible method of tuning the luminescence of these NCs from the UV to the blue spectral region was developed. Using this method, stable aqueous NCs with low Cd content exhibiting the photoluminescence quantum efficiency (PL QE) of 20-30% were obtained.

Ageing as well as chemical and photochemical treatment leading to 3D networking (gelation) in aqueous colloidal solutions of thiol-capped CdTe nanocrystals are investigated. The formation of highly porous aerogels and their optical properties is demonstrated. This approach is suggested for application in optoelectronics and photovoltaics.

The capabilities of two plasma assisted techniques (laser ablation and electrical discharge in liquids) for fabrication of nanoscale composite (Al-Cu/oxide matrix), zinc oxide and doped gadolinium oxide have been presented.

Aqueous solutions of nano-scaled activated Ianthanide orthophosphates LnPO₄:RE³⁺(Ln = Ce, La; RE = Tb³⁺, Eu³⁺, Ce³⁺) have been obtained by the colloidal synthesis method. Kinetics and optimal conditions of the synthesis has been studied. Nanoparticles of 2.1±0.4 nm size and the concentration less than 3.8 g/l are stable in water during 3 months and longer. A possibility to use the nanoparticles as fluorescent probes and labels in biology has been discussed.

We show by X-ray diffraction in the Bragg-Brentano geometry that the atomic structure of lead sulfide nanoparticles in thin films prepared by wet chemical method is different from the B1 structure, which is the equilibrium phase for bulk single-crystalline PbS. The atomic structure of nanoparticles can be described by the cubic space group Fm-3m with both tetrahedral and octahedral coordinations for sulfur atoms.

Optical spectroscopy and small-angle X-ray scattering has been used for study of the nature of color centers in Ce-Ti-doped silicate glasses. In contrast to numerous glasses doped with transition and rare earth elements, the combined coloring effect due to the two oxides originated from appearance of a binary oxide nanophase providing high stability of properties and possibility of easy control of optical features.

Formation of the domain structures in l,2-dipalmitoyl-sn-glycero-3-phosphoholine (DPPC) mixtures with lipids has been investigated. The influence of sphingomyelin (SM), cholesterol (CHL) and quercetin-3-O-palmitate (Q3P) additives on film properties has been studied. Homogeneous film formation, filament structures and solid domains existence have been found by AFM in monomolecular Langmuir-Blodgett films depending on the ratios of lipids. In particular, formation of small domains in threecomponent DPPC:SM:CHL monolayer has been confirmed by AFM at low concentration of CHL (less a 10% molar).

The adsorption of horseradish peroxidase (HRD) on gold and polymer modified resonator surfaces was studied by quartz crystal microbalance. It was shown that the HRP adsorption reached saturation in 5-10 min. The rate constants and the maximum enzyme adsorption were determined. The thickness of HRP/PSS bilayer was calculated.

Nanocomposites involving noble metals nanoparticles and assisted by natural polysaccharide have been fabricated. The plasmon resonance absorption due to nanoparticles has been shown by the method of electronic spectroscopy. Regularities of their formation with target optical characteristics to design new optical materials have been established.

Kinetics of electrochemical co-deposition of nickel with nanodispersed TiO₂, SnO₂, In₂O₃, Fe₂O₃, MoO₃, V₂O₅ and the effect of embedment of oxide particles on the wear-resistance and tribological properties of the resultant nanostructured coating have been investigated. It has been shown that the embedment of MoO₃ nanoparticles with V₂O₅ shell imparts self-lubrication properties to the nickel deposit.

Fe₂O₃–SiO₂ composites containing γ-Fe₂O₃ nanoparticles in an amorphous SiO₂ matrix have been prepared by the inorganic sol-gel method. Structure of the samples annealed at different temperatures was characterized by TEM, XRD, EPR and IR spectroscopy. Magnetic measurements were carried out using the SQUID magnetometry technique.

We have prepared nanoneedles of mixed Co oxide using the sonochemical method for decomposing metal complexes. Resulted nanoparticles are rather well-ordered structures with the average size of 23 nm in length and 5 nm in diameter. Magnetic measurements revealed the ferromagnetic transition at 25 K, which can be explained by the chemical surface modification of the particles.

This experimental investigation focuses on the preparation of polycrystalline magnesium oxide nanorods via capillary-driven infiltration of a precursor solution into the cylindrical pores of a track-etched polycarbonate membrane followed by thermal decomposition procedure. The nanomaterial was fully characterized by SEM, EDX, XRD and photoluminesence (PL) spectroscopy. The investigation of PL properties revealed strong green emission with photon energy around 2.55 eV.

Preformed gold or platinum nanoparticles were ultrasonically treated under argon flow in a home-developed sonoreactor at a constant temperature. Bare gold nanoparticles lose crystallinity in water after 45 min of sonication. Ultrasonic treatment for 20 min in water revealed amorphous platinum nanoparticles with similar catalytic efficiency. The fastest catalysis was accomplished by platinum nanoparticles formed after sonication in an ethylene glycol solution for 20 min, while the lowest one was enabled by platinum nanoparticles after one hour of ultrasonic treatment in presence of poly vinyl pyrrolidone.

The influence of neutral polymer polyethylene glycol and two surfactants with different charge, anionic sodium dodecylsulfate and cationic cetyltrimethylammonium bromide, on the intercalation of pre-formed Au nanoparticles into a clay matrix under ultrasonic treatment has been investigated. The polymer (surfactant) addition has been used to modify the active surface area of Na⁺-montmorillonite and to change the interlamellar space between the clay layers. Then, intercalated polymer (surfactant) in clay composites has been successfully replaced by Au nanoparticles under sonication.

We report on formation of tin-dioxide nanoislands by molecular-beam deposition of Sn on Si/SiO₂ substrates followed by thermal oxidation. The microstructure and phase composition of Sn and SnO₂ nanoislands were studied by TEM. The formation of core-shell SnO₂/Sn structures as well as holes in the SnO₂ nanoislands is documented and found to correlate with the thickness of initial Sn layer and with the oxidation temperature. The results are discussed on the basis of the Kirkendall effect with an additional assumption that absorption of oxygen atoms on the oxide surface creates an electric field that promotes the diffusion of metal ions.

We have studied the effect of preparation procedure, crystallite shape and size, and oxidation conditions on the oxidation behavior of silicon micro- and nanopowders. The oxidation process is shown to occur in two steps, with a transition at a certain thickness of the oxidized layer, which depends on the oxidation time, particle shape, and particle size. The composition and physicochemical properties of the oxide films have been determined in relation to the shape and size of the silicon particles. The results indicate that the silicon micro- and nanopowders differ in oxidation mechanism from single-crystal silicon.

Detonation nanodiamond has been covered by Fe-, Co-, Ni-, Zn-, and Ce-containing nanoparticles prepared via thermal destruction of metal-containing compounds. Composites comprised of the nanodiamonds covered by Fe- and Co-containing nanoparticles embedded within low density polyethylene matrix have been produced. The morphology, size distribution, and composition of the metal nanoparticles as well as magnetic properties of Fe-, Co-, and Ni-containing composites and electric properties of polyethylene-based composites have been studied.

Quantum-chemical simulation in a cluster approach has shown that introduction of hydrogen in silicon nanoclusters leads to initial stages of silicon layers amorphization, whereas oxygen atoms play a role of the stabilizing factor forming initial structures of silicon oxide from amorphized silicon layers. The experiments have demonstrated that H⁺, He⁺ and Ar⁺ ion-beam treatments have a qualitatively similar impact on the electrical properties of Si wafers and are caused by the formation of point defects by ions (independing of ion type) and the creation of donors in the under-surface wafer region (only in a case of H⁺-treatment at elevated temperatures).

New nanocomposites on the basis of metal oxides and mesoporous Ti-silicates were developed and characterized by a set of physical-chemical analysis. The original laboratory scale synthesis technology for manufacture of such materials includes the combination of the following methods: the template method, the methods of microemulsions and microsuspensions.

Features of the nickel electrochemical deposition into mesoporous silicon are discussed. The process was controlled by the surface potential of a sample relative to the reference Ag/Cl electrode. Complete pore filling with metal is reported. Cross-sectional SEM studies of the samples at various deposition stages allowed the deposition mechanism to be revealed.

Porous silicon structures have been studied in order to provide combustion and explosion this material. The combustion process has been observed in the porous silicon layers formed by anodization if the specific area is more than 100 m²/cm³. We have also found that the combustion intensity increases with porous silicon specific area and if the latter is larger than 200 m²/cm³ the explosion process occurs. The time response of explosion development is in the microsecond range.

A characterization of copper/porous silicon (Cu/PS) nanocomposites formed by an immersion displacement method is presented. Morphology and structural properties of Cu-PS samples were analyzed using SEM and XRD techniques. The SEM study demonstrates the complicated structure of the Cu/PS samples. The XRD study confirms that deposited Cu is polycrystalline. Copper deposition time has a strong influence on Cu crystal size and the Cu/PS composition.

Cathodic deposition of metal nanoparticles on silicon typically proceeds via progressive formation of 3D nuclei, which gives opportunity to control electrodeposit properties at the nucleation stage. A complex AC and DC electrochemical characterization technique has been developed for fine tuning the nucleation stage in the formation of metal-silicon nanostructures.

The interaction between H₂ and a Pd-decorated graphene sheet was studied using a first-principles density-functional theory method. Different H₂-Pd systems and adsorption sites were considered, resulting in the most favorable coordination structure on the top site with a relaxed but not dissociated H–H bond. C–Pd bonds are formed during adsorption, while the strength of the Pd–H interaction increased. Pd-decorated graphene can act thus as an effective medium with respect to H₂ abstraction.

A method to check the amorphism of solids is proposed using quantum chemical simulation. LiF and SiO₂ cluster structures are considered and their statistical characteristics are analyzed in order to illustrate the methodology.

An adsorption of silver dimer on a rutile (110) surface has been studied using a DFT model within both cluster and periodic approaches. The calculations show that the interaction of silver dimers can occur both with bridging chain of oxygen atoms or with atoms located in the hollows between chains. The bonding of Ag₂ in the hollow is characterized by the positive adsorption energy according to the periodic model. On the other hand, the geometry optimization of similar structures within the cluster model leads to desorption or dissociation of silver dimer. The periodic model is shown more appropriate for this system.

Electronic absorption and emission spectra of Au₈ cluster have been calculated using time-dependent density functional theory (TD-DFT). The calculations predict a large Stokes shift for Au₈ cluster. It has been shown that the calculated absorption spectrum is in good agreement with the experimental data.

A novel method for determination of the particle contact angle at the fluid/fluid interface based on the excluded area concept revealed some serious difficulties connected with the exact quantitative particle deposition at the interface and with changes in the particulate contact angle upon binary monolayer compression. The comprehensive theoretical consideration of the contact angle behavior made for such system allowed considerable improvement of the proposed method that was then successfully proven by experimental data.

The influence of the particle size on chemical reactions in nanoscale particles is studied theoretically. The dependence of the rate of chemical reaction on the particle size is considered by the example of silicon nanoparticle oxidation.

A mathematical model of a nanoparticles growth during evaporation of a micron size droplet in a low pressure aerosol reactor is developed. The main factor is found to be evaporating cooling of droplets which affects formation of supersaturated solution in the droplet. The rate of cooling can reach 2 · 10⁵ K/s. The final radius of nanoparticles was found to be independent on the precursor radius. Manifestation of Lifshitz–Slezov instability is illustrated by experimental data. Effects of Brownian motion of nanoparticles inside the droplet are discussed.

Microstructural changes of amorphous carbon (a-C) and tetrahedrally amorphous carbon (ta-C) upon laser irradiation is studied in this paper. As it is shown, ta-C films with higher ratio of sp³ bonded carbon atoms are more stable compare to low density a-C films. The sp² bonded atoms in a-C films start clustering at laser energies lower than the energy needed for clustering of sp² bonded atoms in ta-C films.

We have studied the possibility to fabricate ultrahigh packed pit and dot arrays using 30 kV conventional electron beam (EB) drawing, and to form fine magnetic column arrays using EB drawing and ion milling for patterned media in the future magnetic storage. We investigated which positive or negative EB resist is suitable for fine pattern formation using ZEP520 and calixarene. We studied the resist thickness dependence of very fine pitch pattern in EB drawing. Also, we tried to form nanometer-sized magnetic dots. As experimental results in the 30keV-EB drawing with the negative resist, we demonstrated to achieve 20 nm pitched resist dot arrays on Si, althogh near 25-nm-pitched dot arrays on PtCo magnetic and thin metals layers on glass substrate have been drawn. In the ion-milling, we demonstrated to achieve fine magnetic column arrays with a diameter of 39 to 106 nm and a space of 100 nm using 200 eV Ar ion-milling. Furthermore, we have confirmed nanometer size effect of the magnetic column in coercive force. These experiments can open a way toward over 1 Tb/in² storage.

There is an overview of the probe nanotechnology research in the Center of Probe Microscopy and Nanotechnology of MIET (TU). We demonstrate the results in development of quasi-one-dimensional metallic and carbon electronics, carbon nanotubes production, sensor application, and graphene based nanosystem devices.

The finite-size and neighboring effects in nanostructured magnetics deposited into porous anodic alumina (PAA) are analyzed. The critical parameter to produce single-domain magnetic nanopillars in PAA pores, enabling maximum magnetic susceptibility and reproducibility, is the pillars aspect ratio about 10. The results allow choosing the optimum processing conditions and design solutions for magnetic sensitive media based on PAA/magnetic nanocomposite.

During the last years, a growing interest in the creation of micro- and nanoelectronic devices by use of the swift heavy ion track technology in a combination with carbon nanotubes (CNTs) is observed in several research centers worldwide. The CNTs were grown in etched ion tracks in SiO₂ layers on Si. For this purpose, Ni-catalyst nanoclusters were electrochemically deposited within the ion tracks. The geometry of the obtained nanostructures has been analyzed. Structure features of CNTs obtained by thermal chemical vapor deposition have been investigated.

Vertically aligned CNT arrays have been synthesized on Si/SiO₂ substrate by the high temperature pyrolysis of p-xylene and ferrocene mixture. The synthesized CNT arrays were investigated by SEM, TEM, Raman, and TGA. It was found that along with MWNTs the oriented SWNT bundles were grown in the CNT arrays. The lower concentration of catalyst resulted in the higher quality of CNTs in the array, the smaller SWNTs diameter, the lower burning temperature of the specimen in TGA and the higher percentage content of SWNTs in the array. The synthesized CNT arrays are pure enough to be directly used in different applications without purification.

Technological features of nanoprofiling of silicon protected by a solid mask made of porous aluminum oxide are considered. It is shown that the method based on bombarding structures with accelerated neutral atoms (in particular, argon atoms) is efficient for etching through this mask.

This work describes the protection of hydrogen storage materials by their encapsulation. The shell provides stability and selective permeability due to complex formation. Sodium borohydride particles were encapsulated within polymer films by the layer-by-layer self-assembly of oppositely charged polyelectrolytes (polyethyleneimine and poly (acrylonitrile-co-butadiene-co-acrylic acid)).

The formation of defects in porous anodic alumina films fabricated in phosphoric acid solutions has been studied. TEM and SEM examinations revealed that defects appear at the triple point junctions of the cell boundaries, where neighbouring cells meet. The defects represent voids in the anodic alumina and develop into spatial structures that comprise a central void at the triple-point junction extending into tubular branches that pass toward the pore wall. The defects are generated continuously during the anodic film growth under appropriate anodising conditions. Additional post-anodising treatment also results in periodic arrays of circular nanoholes in the pore walls.

Etching of masked Si (001) surface in KOH (10-16 mol·l^-1) at temperature 60-80 °C is investigated. The orientation and etch rate of the micro- and nanosurfaces undercutting convex corners of 3D-structures formed under the right convex comer of the mask with the edges of different alignments were determined. The effective activation energy of the etching process of the surfaces was estimated.

Constant height repulsive (pushing mode) manipulation of a C₆₀ molecule covalently bound to the Si(001) surface is modelled using ab initio density functional theory, with the scanning tunneling microscope tip included explicitly in the calculations. The formation of chemical bonds between the tip and the molecule is demonstrated. The bonds between the molecule, tip and surface are constantly rearranging, so that a continuous manipulation process is possible. Tip-induced manipulation considered here is compared with the tip-free model, and the effects due to the tip are discussed.

Substrates for surface-enhanced Raman scattering (SERS) were prepared by vapor deposition of silver directly onto the surface of porous alumina. Silver nanostructures have been characterized by SEM and UV-Vis absorption. The SERS-activity of the substrates tested with water-soluble cationic Cu-porphyrin as a probe molecule, attained the maximum when Ag mass thickness was approximately 60 nm.

Silver films are formed on meso- and macroporous silicon (meso-PS and macro-PS) by the immersion plating. Scanning electron microscopy reveals the formation of Ag islands along the dendritic structure at the surface of meso-PS and Ag nanoparticles over the pore walls in the case of macro-PS. The surface-enhanced Raman scattering activity of Ag-macro-PS substrates appears to be greater in comparison with that for Ag-meso-PS.

The staging realization of structural transformations in Bi_1.8Y_1.2Fe₅O_12-δ films during heating with various oxygen pressures (pO₂) is revealed at the analysis of oxygen exchange processes between the film and gas environment. It is established that the films annealed at 680 °C and pO₂ = 10⁵ Pa during 30 min show improved structural, optical and magnetooptical characteristics. This is caused by a crystallization of the amorphous film, a decrease of anionic vacancies and a compression of the charge disproportionation process Fe³⁺↔Fe⁴⁺ + Fe²⁺.

Novel light-controllable coating for corrosion protection are proposed. The coatings consist of porous titania particles with polyelectrolyte shell which are embedded into the organosiloxane matrix. These coatings provide controllable protection against corrosion due to stimulated release of encapsulated inhibitor under local irradiation with UV or IR laser. The healing ability of damaged photocontrollable coatings was demonstrated with the use of scanning vibration electrode technique (SVET). Laser-induced release of incorporated corrosion inhibitor (2-(benzothiazol-2-ylsulfanyl)-succinic acid (BSA)) from nanoengineered containers was observed both on single and multi container levels.

Stable polyelectrolyte microcapsules were produced by means of the layer-by-layer adsorption of protamine and alginic acid on the surface of calcium carbonate microcores followed by the cores dissolution at low pH. The capsules obtained were investigated by atomic force microscopy and confocal laser scanning microscopy.

Platelet surface morphology change and platelet aggregation were investigated by SFM after adhesion events to mica and after addition of adenosine diphosphate (ADP) alone and ADP with H₂O₂. Activated platelets release biologically active compounds, which can recruit both additional platelets and other blood cells (leucocytes, red blood cells) into a growing thrombus. The complex structure of thrombus was visualized with SFM.

This study briefly introduces both the surface morphology features of K562 cells and their internal ultrastructure. Using scanning force and confocal laser scanning microscopy allows us to visualize K562 cell surface morphology details such as the membrane convexities, different kind of surface microvilli, the plasma membrane surface knobs.

A test structure for SPM cantilever tip shape deconvolution is described. The structure is based on aluminum with ordered tip-like surface. This structure is created by anodic oxidation of aluminum with subsequent selective etching of anodic alumina film. The developed structures consist of aluminum base with sharp tips of alumina. It is found that curvature radius of the tips are as small as 2 nm. Various types of tip shapes were charaterized by this structure. Experimental studies of the developed test structure containing an array of sharp tips may be used for three-dimensional imaging of the SPM tips.

The current status of investigations of spin valve effects in structures composed of superconducting and ferromagnet layers is briefly reviewed. The main difficulties on the way of realization of SF spin valve devices are outlined. It is demonstrated that some of them can be effectively overcome by the use of trilayer ferromagnetic – normal metal – ferromagnet structures as a weak link of Josephson junctions.

The paradigm of sensor miniaturization dominates nowadays in the sensor research and development. The past decades have shown that the downsizing of sensing elements and devices not only makes them cheaper and more economical but also improves the sensor performance opening therefore great technological perspectives. This work addresses the key steps required for the development of metal-oxide-based gas nanosensors, stretching from the synthesis of shape- and size-controlled materials, via the integrative approach to the metal oxide sensing films fabrication, to the real-time studies of gas sensing mechanisms on operating sensors.

We demonstrate a novel method for constructing biomolecular nanoarrays in a nanopatterned inert material on a gold substrate. UV-NIL was used to fabricate nanostructures of UV-curable PEG and PVA. These inert hydrogels strongly restrict the adhesion of proteins and tethered bilayer lipid membranes, resulting in an array of highly selective hydrogel nanowells. Direct patterning of inert materials using UV-NIL is simple and efficient for constructing biomolecular nanoarrays using stepwise self-assembly.

Problems of physical limits for miniaturization of electronic devices in integrated circuits are discussed. The quantization of both electrical and thermal conductance in nanostructures is considered and estimated numerically. Problems of heat exchange in nanostructures are also discussed.

Metal nanoparticles can increase the modulation band of semiconductor LEDs. This is demonstrated theoretically on example of "nano-LED" (NLED) composed of a single q-dot and nanoparticle (nanoantenna). NLED is analogous to dipole nano-laser (DNL) [1] working below threshold. NLED can operate separately or in groups providing nano- or macro-source of bright light. Conditions necessary for NLED operation are estimated.

This paper summarizes recent developments in the search for materials and designs that can lead to lasing without global population inversion in the far infrared based on intersubband devices. The recent proposal of using the strong k-dependence of the transverse electric dipole moment to filter local inversion of nonequilibrium holes in the valence subbands of III-V quantum wells is discussed.

The organic transistor of vertical structure on the basis of poly(diphenylenephthalide) have been fabricated. A possibility of conductivity control between the upper and bottom electrode by changing potential on the middle electrode was shown.

The electrophysical parameters of three-gate short n-channel MOSFETs in comparison with those of conventional single-gate MOSFETs are investigated. By means of Monte Carlo simulation such parameters as, in particular, electron energy and mobility are calculated. It is shown that under certain conditions the values of these parameters may be higher in three-gate MOSFETs.

Effect of micromorphology, electrical properties, and technological regimes on photovoltaic efficiency of SnO₂:F/TiO₂/In₂S₃/In_xPb_1-xS/CuSCN extremely thin absorber solar cells is investigated. It is shown that sol-gel deposition of TiO₂ under increased humidity leads to formation of more rough nanocrystalline film with reduced resistivity. It is found that Ni contact to CuSCN layer has minimum series resistance compared with In, Cu, and Au based contacts. Performed optimization of TiO₂ microstructure and minimization of contact resistance results in more that 4 times higher photovoltaic conversion efficiency. The optimized solar cells developed in this work demonstrated J_SC = 9 mA/cm², V_oc = 720 mV, and η = 2.9%.

The possibility of 1.5 µm ultrafast all-optical modulator realization based on GaAs/(AlGa)_xO_y heterostructures is discussed. The excitation of the samples by 150 fs laser pulses leads to about 25 nm shift of the reflection spectrum. The mean decay time for nonlinear reflection in heterostructures ranges from 1.0 to 2.5 ps.

According to theoretical and experimental results obtained recently a dc voltage can be induced by a switching of superconductor ring between states with different connectivity of wave function. This effect can be used for development of a quantum detector of noise with the ultimate sensitivity. Our experimental investigations confirm such possibility.

We have investigated the impacts of ⁶⁰Co-gamma-ray (83 kGy) and pulsed laser (1-80 µJ) irradiations on silica, optical glass, synthetic alumina, silica powder, films, and films with nanocrystals. Substrates and matrices samples from various sources were studied, including fused silica and CaF₂, LiF crystals with a given content of oxygen, hydroxyl and metal impurities. Relationships between the content of impurities, colloids and properties of undoped bulks, powders, films were examined. Microstructure testing, luminescence and pump-probe nonlinear optical (NLO) experiments indicate possible origin (crystallinity, texture increase, defect reduction, colloids formation) of the ultrafast NLO effects enhancement detected in film nanocrystals at extra excitation power, pulse durability, and γ-irradiation.

An electrochemical Pt deposition from the diamine nitrite solution onto monocrystalline, macro- and mesoporous silicon is presented. Pt grain size versus deposition time was determined from the SEM data. A catalytic reactivity of the Pt coated electrodes was estimated by the calculation of the effective surface area with a voltammetry technique. A considerable gain in the catalytic reactivity was found to be obtained by using mesoporous silicon in comparison with the macroporous electrode.

New kinds of dilute-nitride type-II InAsN/GaSb laser diodes on InAs substrate with "W" or "M" design are theoretically investigated. For these laser diodes, designed to operate at 3.3 µm at room temperature, the total threshold current densities are calculated. Under the hypothesis of a total loss coefficient α = 50 cm^-1, these multiquantum well laser structures present a calculated threshold current density J_th lower than 1.1 kA/cm².

Structural features of thin-film γ-Fe₂O₃/In₂O₃ hetero-junctions and their gas-sensing features have been studied. Two mechanisms of adsorbed CH₄ molecule effect on electric conductivity of the layers depending on operating temperature were proposed.

The fabrication of LEDs based on thiol-capped nanocrystals by the layer-by-layer deposition technique is presented and discussed. This technique is generally applicable to LEDs efficiently emitting in the wide spectral region from UV through near-IR.

New results on the influence of uniaxial stress up to P = 4 kbar along [110] and [1-10] directions on the electroluminescence spectra of laser diode nanostructures p-Al_xGa_1-xAs/GaAs_1-yP_y/n-Al_xGa_1-xAs are presented. With the increasing stress, the emission spectra demonstrate a blue shift of up to 20-25 meV at P = 3-4 kbar, while the electroluminescence intensity and light efficiency increase under compression. The results are discussed in terms of changes in the band structure under an uniaxial compression.

Anisotropic optical properties of free nanoporous anodic alumina films transparent in the visible spectrum for the restricted range of pore diameters and pore intervals are discussed. The basic experimental procedure is presented for the production of these films. Light scattered along pores was experimentally found to have partially a polarization perpendicular to the polarization of the incident light. The results obtained show that the nanoporous structure of anodic alumina films can be purposefully used in LCD to control a light propagation.

Implementing bioanalogous recognition properties within man-made materials opens up the way for generating highly functional yet robust matrices that can e.g. be applied as chemical sensor layers. Triazine pesticides for instance are suitable templates for generating selective recognition sites in more polar systems such as polyacrylic acids. As coatings on a quartz crystal microbalance, they can be utilized for detection of atrazine in water down to the low ppb level. Selectivities of the resulting materials can be appreciably high: terpenes can be distinguished by at least a factor of three, which can be utilized for characterization of a terpene emission pattern from different plant materials directly on-line.

The present work describes the synthesis of ferroelectric-ferrimagnetic multilayers for possible device applications. The sol-gel spin coating technique is employed for the synthesis of heterolayers consisting of PZT and nickel ferrite using nitrate precursors. The multilayers are sintered in a rapid sintering process. The morphological characterization using AFM shows that the multilayers are smooth, with nanosized grains. The local piezoelectric measurements using PFM deliver a piezoelectric loop even if the multilayers consist of small grained PZT particles. The magnetic characterization using SQUID shows ferromagnetic ordering.

An equivalent circuit of resonant-tunneling nanostructures taking into account spin-polarized transport of charge carriers is proposed. It is based on the approximation of I-V characteristics and represents spin shifted energy levels in the quantum well.

Nanostructures based on C₆₀ (fullerite) deposited into swift heavy ion (SHI) tracks in a polyimide layer on a silicon substrate have revealed the pronounced sensitivity to humidity and temperature, which can be associated with the mobility of H⁺ and OH^- ions within the fullerite lattice and electrochemical corrosion in humid environment in the presence of moisture. These sensor effects are larger in the structures with SHI tracks as compared with the structure without the tracks.

Vacancy-related complexes which were generated in silicon p⁺-n diodes by irradiation with 6 MeV electrons in the temperature range of 350-800 K have been studied by means of deep level transient spectroscopy. Such defects are of interest because of their possible application in controlling the carrier lifetime in silicon power devices. Electronic parameters of defects incorporating up to three vacancies and an oxygen atom have been determined. Total introduction rate of radiation-induced defects increased about twice upon raising the irradiation temperature from 350 to 675 K.

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