Germanium-cobalt-indium (Ge-Co-In) nanostructures are a promising material for negative electrodes of lithium- ion batteries aimed for arctic exploitation. Electrochemical impedance spectroscopy was used for a detailed study of the interaction of Ge-Co-In nanostructures with lithium in a temperature range from -35 to +20 degrees C. The discharge capacity at temperatures of 20, 0, -10, -20, and -35 degrees C amounted to 1400, 1228, 1040, 907, and 793 mAh g-1, respectively. The impedance spectra measured at various lithiation degrees were found to differ but insignificantly whereas temperature variation resulted in notable changes in the spectra. A normalized charge transfer resistance for Ge-Co-In nanostructures was significantly (more than an order of magnitude) less than for Ge-In nanowires (obtained by the same method, but without the addition of cobalt salt into the electrolysis solution). It is this difference in charge transfer resistance that can explain the difference in the shapes of the impedance spectra for both objects. Also, in contrast to data for Ge-In nanowires, the dependences of the lithium diffusion coefficient in Ge-Co-In nanostructures on potential had a clearly defined minimum. The lithium diffusion coefficient in Ge-Co-In nanostructures slightly exceeded that in Ge-In nanowires, and the activation energy of lithium diffusion in Ge-Co-In nanostructures was marginally less than in Ge-In nanowires.

The aim of this work is to study of germanium nanowires as low temperature and high charging rate lithium‐ion battery anode material. Using a full cell with a cathode based on NMC811 and an anode based on synthesized germanium nanostructures in combination with the proposed electrolyte composition, we demonstrate the ability to charge and cycle the battery at temperatures as low as −40°C. The results generally indicate that using germanium nanowires as anode material in lithium‐ion batteries may solve the problem of their reversible and safe charging at sub‐zero temperatures.

Using photoluminescence and Raman spectroscopy, as well as high-resolution transmission microscopy and X-ray diffraction, germanium nanowires obtained by cathodic deposition from an aqueous solution of germanium dioxide were studied during their annealing by a laser at 720 °C under ambient conditions. It is established that the dynamics of Raman and photoluminescence spectra are related to the oxidation of wires during such annealing. The study showed that vacuum annealing of as-grown nanowires at 600 °C for 30 min suppresses laser high-temperature germanium oxidation. The observed effect is associated with the saturation of vacancies in the surface germanium suboxide with indium atoms used as a catalyst in the formation of nanowires.

Understanding the formation and evolution of arrays of metallic nanoparticles is a very important task as they are increasingly used in various devices. In this work, we used HRTEM mode for continuous in-situ observations of the evolution of Ag and Au nanoparticle arrays with an average size of similar to 4 nm, formed on the surface of amorphous carbon by vacuum-thermal evaporation, under the influence of a microscope electron beam without any other energetic influence. Our studies show that electron beam exposure induces a process of nanoparticle coalescence for Au and simultaneous coalescence and vaporization for Ag. As a result, the evolution of Ag and Au nanoparticle arrays has different mechanisms. In the case of Ag, the aggregation of nanoparticles occurs through the gas phase by the Ostwald ripening mechanism. In the case of Au, it was found that the aggregation of nanoparticles depends on their mutual crystalline orientation, resulting in the realization of mechanisms through bridge formation or through jumping. The influence of the crystalline orientation of the nanoparticles on the coalescence mechanism was confirmed by molecular dynamics simulations. MD simulations revealed that it is most favorable for coalescence if the densely packed planes of neighboring nanoparticles have a perpendicular arrangement in space.

Test structures in the form of rectangular boxes fabricated on thermal silicon dioxide substrates under normal and oblique ion bombardment using the focused ion beam technique were studied by transmission electron microscopy and energy-dispersive X-ray microanalysis. The experimentally obtained depth distribution profiles for gallium atoms, as well as the sputtering yields, were compared with the results of Monte Carlo simulations. Calculations were carried out using standard continuous and discrete-continuous models for the surface binding energy of atoms in silicon dioxide. For the normal incidence of the ion beam, based on minimizing the value of the R-factor, which characterizes the agreement between the calculated and experimental data, the optimal values of the parameters of the discrete-continuous model were found, which turned out to be close to the values used in the continuous model. It is shown that the obtained parameters make it possible to simulate silicon dioxide sputtering with acceptable accuracy at ion beam incidence angles of 15° and 30°. However, at a grazing incidence angle of 80°, significant differences arise between the experimental and calculated profiles of the concentration of gallium atoms implanted in silicon dioxide.

The methods of transmission electron microscopy and high-resolution electron microscopy, used to study multilayer heterocomposites, have limitations in resolution, do not allow for the effective investigation of amorphous materials and require the analysis of many local areas in the case of samples consisting of individual crystallites. In this work, we investigate a multilayer heterocomposite, which is a phase-shift photomask consisting of layers of nanoscale thickness on the surface of a glass substrate. Focused-ion-beam methods are used to study a thin foil of cross and longitudinal sections. To identify the structure and determine the composition of the layers, the methods of transmission electron microscopy and energy-dispersive X-ray microanalysis are used. The analysis of cross-sectional foils prepared using standard approaches allows visualization, thickness measurements, and determination of the layer compositions. It is shown that on the SiO2 substrate an amorphous layer of Mo0.06Si0.31N0.63 93 nm thick is formed, which is successively coated with polycrystalline layers of Cr0.56N0.44, Cr0.74C0.06N0.2, and Cr0.4N0.26O0.3 with thicknesses of 22, 37, and 8 nm, respectively. A thin foil with a planar cross-section, prepared at a slight inclination to the surface of the photomask, makes it possible to form sections of all layers with dimensions sufficient for their study by electron microdiffraction. The performed electrographic analysis confirmed the amorphous structure of the substrate and Mo0.06Si0.31N0.63 layer, and also showed that polycrystalline layers of Cr0.56N0.44, Cr0.74C0.06N0.2, and Cr0.4N0.26O0.3 formed by crystallites with a cubic lattice and parameters of 3.92, 4.18, and 4.12 Å, respectively.

Revealing the regularities of interaction of accelerated ions with an irradiated material based on the Monte Carlo simulation contributes to the efficient application of focused ion beam technique in modern nanotechnologies. The correctness of the calculation results depends on the model chosen and the parameters determining the surface binding energy (SBE) of sputtered atoms. In this work, the SBE has been determined within the discrete–continuous model, which makes it possible to consider the formation of gallium precipitates during irradiation of a silicon substrate with gallium ions. To compare the simulation results with the experimental data on material sputtering by a focused ion beam, two types of rectangular boxes have been prepared. The structures of the first type were formed at the same dose, close to 5 × 10 17 cm –2 (corresponding to the steady-state sputtering regime), at accelerating voltages of 8, 16, and 30 kV. The structures of the second type were formed at an ion energy of 30 keV and doses of 2.5 × 10 16 , 5 × 10 16 , and 1 × 10 17 cm –2 . The box cross sections were investigated by transmission electron microscopy. The sputtering yield and depth distribution profiles of gallium atoms, calculated in the SDTrimSP 5.07 software package, were compared with the experimental data using the R factor. Two sets of values have been established for the variable parameters: the SBE of gallium atoms and the α 1 parameter of the discrete–continuous model. The first set describes the experimental data with acceptable accuracy for a small number of implanted gallium atoms, which is implemented for low ion doses, as well as for a beam energy of 8 keV and a dose of 5 × 10 17 cm –2 . The second set is optimal for describing the ion beam interaction with the substrate at ion energies of 16 and 30 keV under steady sputtering conditions.

Silver is one of the most promising nanomaterials for plasmonic applications, but it has become clear that the shape and internal symmetry of nanoparticles can significantly affect the scattering and absorption of light waves. Therefore, for the use of silver nanoclusters in plasmonic applications, it is very important to determine the conditions of stability of the structure and form of Ag nanoparticles. To this end high-resolution electron microscopy was used to examine initial and annealed arrays of silver nanoparticles with diameters ranging from 0.8 to 9.4 nm, formed on a carbon substrate by vacuum thermal evaporation. It was found that small Ag nanoparticles (D < 3.0 nm) have almost perfect FCC structure, while nanoparticles of larger diameter unexpectedly have predominantly icosahedral or decahedral facets. To explain this contradiction from the perspective of standard crystallographic theory, molecular dynamics simulations using the TB-SMA potential were conducted to study the stability limits of structural modifications of silver nanoclusters of similar diameters, and possible atomic rearrangement mechanisms that could lead to such experimental results were found. Based on the results of the computer analysis, conclusions were drawn about the technological possibilities of creating the desired crystal structure of Ag nanoparticles when preparing SERS substrates.

We investigated the chemical beam epitaxy of GaP1−xNx grown on nominally (001)-oriented Si substrates, as desired for the lattice-matched integration of optoelectronic devices with the standard Si technology. The growth mode and the chemical, morphological, and structural properties of samples prepared using different growth temperatures and N precursor fluxes were analyzed by several techniques. Our results show that, up to x≈0.04, it is possible to synthesize smooth and chemically homogeneous GaP1−xNx layers with a high structural quality. As the flux of the N precursor is increased at a given temperature to enhance N incorporation, the quality of the layers degrades upon exceeding a temperature-dependent threshold; above this threshold, the growing layer experiences a growth mode transition from 2D to 3D after reaching a critical thickness of a few nm. Following that transition, the morphology and the chemical composition become modulated along the [110] direction with a period of several tens of nm. The surface morphology is then characterized by the formation of {113}-faceted wires, while the N concentration is enhanced at the troughs formed in between adjacent (113) and (1¯1¯3). On the basis of this study, we conclude on the feasibility of fabricating homogeneous thick GaP1−xNx layers lattice matched to Si (x=0.021) or even with N content up to x=0.04. The possibility of exceeding a N mole fraction of 0.04 without inducing coupled morphological–compositional modulations has also been demonstrated when the layer thickness is kept below the critical value for the 2D–3D growth mode transition.

The level set method was generalized for simulating the evolution of the surface of multilayer substrates under focused ion beam irradiation. For a correct description of such process the calculations took into account the sputtering yield angular dependences, the densities of the irradiated materials and it was considered that sputtered atoms can escape from different layers of the substrate. Comparison of the calculation results with experimental data for test structures formed in a two-layer silicon dioxide–crystalline silicon substrate showed that the developed simulation method makes it possible to predict the shape of structures fabricated by a focused ion beam with good accuracy.

The level set method was generalized for simulating the evolution of the surface of multilayer substrates under focused ion beam irradiation. For a correct description of such process the calculations took into account the sputtering yield angular dependences, the densities of the irradiated materials and it was considered that sputtered atoms can escape from different layers of the substrate. Comparison of the calculation results with experimental data for test structures formed in a two-layer silicon dioxide-crystalline silicon substrate showed that the developed simulation method makes it possible to predict the shape of structures fabricated by a focused ion beam with good accuracy. Keywords: Focused ion beam, sputtering, level set method.

We investigated the chemical beam epitaxy of GaP1-xNx to correlate the growth parameters with their properties when they are grown on nominally (001)-oriented Si substrates, as desired for the lattice-matched integration of optoelectronic devices with the standard Si technology. The growth mode as well as the chemical, morphological and structural properties of samples prepared using different growth temperatures and N precursor fluxes were analyzed by RHEED, XRD, RBS, NRA, EDX spectroscopy, AFM and TEM. Our results show that, up to x = 0.04, it is possible to synthesize smooth and chemically homogeneous GaP1-xNx layers with a high-structural quality in a 2D fashion, namely, layer-by-layer. For a given N mole fraction, the layer-by-layer growth mode is favored by lowering the growth temperature while decreasing the N precursor flux. As the flux of the N precursor is increased at a given temperature to enhance N incorporation, the quality of the layers degrades upon exceeding a temperature-dependent threshold; above this threshold, the growing layer experiences a growth mode transition from 2D to 3D after reaching a critical thickness of a few nm. Following that transition, the morphology and the chemical composition become modulated along the [110] direction with a period of several tens of nm. The surface morphology is then characterized by the formation of {113}-faceted wires, while the N concentration is enhanced at the troughs formed in between adjacent (113) and (-1-13) facets. We conclude on the feasibility of fabricating homogeneous thick GaP1-xNx layers lattice matched to Si (x = 0.021) or even with N content up to x=0.04. The possibility of exceeding a N mole fraction of 0.04 without inducing coupled morphological-compositional modulations has also been demonstrated when the layer thickness is kept below the critical value for the 2D-3D growth mode transition.

The original version of a negative electrode of lithium-ion battery is prepared. To this end the arrays of Ge nanowires were electrodeposited from an aqueous solution onto a titanium substrate with drop-like indium crystallization centers. The nanowires were characterized by SEM, TEM, EDX, XPS, galvanostatic cycling, CV, and EIS. Electrochemical tests were carried out in a wide temperature range with using the propylene-carbonate-based electrolyte. The electrochemical performances of the nanowires were shown to be dependent on the current density upon electrodeposition. The nanowires with diameter 20 to 40 nm and length up to 0.5 mu m are covered with a thin oxide layer, consisting of both stoichiometric and non-stoichiometric germanium oxides. The electrodes demonstrate excellent features, namely room-temperature specific capacity ca. 1300 mAh g(-1) at 1C and 4C rate, and about 850 mAh g(-1) at 24C, as well as good low-temperature performance, 255 mAh g(-1) at -50 degrees C.

Semiconductor industry calls for emerging memory, demonstrating high speed (like SRAM or DRAM), nonvolatility (like Flash NAND), high endurance and density, good scalability, reduced energy consumption and reasonable cost. Ferroelectric memory FRAM has been considered as one of the emerging memory technologies for over 20 years. FRAM uses polarization switching that provides low power consumption, nonvolatility, high speed and endurance, robust data retention, and resistance to data corruption via electric, magnetic fields and radiation. Despite the advantages, market share held by FRAM manufacturers is insignificant due to scaling challenges. State-of-the-art FRAM manufacturing is studied in this paper. Ferroelectric capacitors and memory cells made by main commercial FRAM manufactures (Texas Instruments, Cypress Semiconductor, Fujitsu и Lapis Semiconductor) are explored. All memory cells are based on the lead zirconate titanate PZT capacitor with the thickness of about 70 nm and IrOx/Ir or Pt electrodes. The leading FRAM technology remains the 130 nm node CMOS process developed at Texas Instruments fabs. New approaches to further scaling and new devices based on ferroelectrics are reviewed, including binary ferroelectrics deposited by ALD techniques, piezoelectronic transistors, ferroelectric/2D-semiconductor transistor structures, and others. Whether FRAM technology will be able to resolve one of the main contradictions between a high-speed processor and a relatively slow nonvolatile memory depends on the success of the new technologies integration.

Metallic nanoparticles are promising objects of study, since their properties greatly differ from the properties of bulk material. In analyzing nanoparticles, it is important to investigate their size, stability, structural features, and spatial arrangement. In this study, initial and annealed silver nanoparticles from ∼2 to 10 nm in size formed on a carbon substrate by vacuum thermal evaporation are investigated by high resolution transmission electron microscopy and their shape and structure are classified. The examined nanoparticle types include faceted ellipsoid ones with a polycrystalline structure, coarse ones with a single-crystal structure and twins, icosahedral and decahedral ones with multiple twinning, and fine single-crystal nanoparticles smaller than 3.5 nm. It is established that, after annealing, the total number of nanoparticles decreases by a factor of ~1.3, the number of fine nanoparticles almost halves, and the fraction of nanoparticles with icosahedral and decahedral cross sections increases by a factor of ~1.5. It is shown that nanoparticles smaller than 5 nm become unstable already after a few seconds of exposure to high-energy electrons. For fine single-crystal nanoparticles smaller than 3.5 nm, the average crystal-lattice parameter is found by precise determination of the centers of atomic columns in their images and calculation of the local distances between atoms located in the mutually perpendicular (200) and (022) planes. It is shown that, in such nanoparticles both before and after annealing, there are no noticeable crystal-structure distortions and their lattice parameter is similar to the value characteristic of bulk silver.

The processes of redeposited and crystalline silicon sputtering under focused Ga ion-beam irradiation are simulated using the Monte Carlo method and different models of the surface binding energy of Si and Ga atoms. The sputtering yields and the profiles of the distribution of Ga atoms in the sample, calculated for different ion energies, are compared with the experimental data. It is established that the introduced model of the surface binding energy of Si and Ga atoms, taking into account the formation of Ga precipitates in the near-surface region of the sample, makes it possible to reach the best agreement with the experimental data.

The structure of carbon nanopillars grown without catalysis by low-temperature plasmaenhanced-chemical-vapor deposition on a silicon substrate is investigated using the suggested focused ion beam technique for preparing a sample composed of several thin plan-view foils. Studying the prepared sample by electron diffraction and bright-field transmission electron microscopy allows determination of the variation of the two-dimensionally ordered crystallite fraction along the growth direction. It us established that the crystalline phase fraction inside the nanopillars gradually decreases during the growth process. Nearly 90% of the crystalline material is located between the base and the middle of the nanopillars while their upper parts almost entirely consist of amorphous carbon.