The influence of methane plasma parameters on the deposition rate and on the content of the hydrogen and the sp3-carbon fraction in hydrogenated diamond-like carbon films (DLC) was investigated. It was shown that the proportion of the sp3-carbon fraction mainly depends on the inductive power and the argon addition to the plasma; the latter also contributes to a decrease of hydrogen in the films.

Room temperature lateral p+-i-n+ light-emitting diodes (LEDs) with photonic crystals embedded in the i-region were fabricated on structures with Ge(Si) self-assembled islands and their optical properties were investigated. The use of preliminary amorphization and solid phase epitaxy of the implanted p+ and n+ contact regions made it possible to reduce the impurity activation temperature from 800 degrees C-1100 degrees C to 600 degrees C, which corresponds to the growth temperature of Ge(Si) islands. This resulted in a significant reduction of the detrimental effect of the high-temperature annealing used for diode formation on the intensity and spectral position of the luminescence signal from the islands. It was shown that significant enhancement (more than an order of magnitude) of room temperature electroluminescence of Ge(Si) islands in the spectral range of 1.3-1.55 mu m can be achieved due to their interaction with different modes of the photonic crystals. The measured radiation power of the obtained diodes in the spectral range of 1.3-1.55 mu m exceeds 50 pW at a pump current of 8 mA, which is an order of magnitude higher than the previously achieved values for micro-LEDs with Ge(Si) nanoislands. The obtained results open up new possibilities for the realization of silicon-based light emitting devices operating at telecommunication wavelengths.

Light-emitting transistors (LETs) represent the next step in the development of light-emitting diodes (LEDs), offering additional control over emission. In this work, the transport properties and spatial distribution of electroluminescence (EL) in the spectral range of 1.2-1.7 mu m were studied for lateral p(+)-i-n(+) LEDs based on silicon-on-insulator structures with self-assembled Ge(Si) islands embedded in photonic crystals. It is shown that due to the low mobility of holes and their effective trapping in the islands, the maximum EL yield is observed at the i/p(+) junction of the LED. It is demonstrated that the sign and magnitude of the bias voltage applied to the substrate (to the gate) have a significant influence on the transport and emission properties of the LEDs with Ge(Si) islands, turning them into LETs. In particular, applying a negative gate voltage shifts the position of the maximum emission region from the i/p(+) to the i/n(+ )junction of the LET, which is related to the formation of a hole conductivity channel near the buried oxide layer. The embedding of a specially designed photonic crystal in the i-region of the LET makes it possible to manage the spectral properties of the near-IR emission by changing the sign of the gate voltage. The results obtained may be useful for the future development of optoelectronic devices.

The paper presents the results of mechanical and electrical tests of composite materials based on biodegradable polymers (polyvinyl alcohol, polyacrylamide, starch) and synthetic layered double hydroxides (Ni–Al, Zn–Al) obtained by two-stage (chemical) and one-stage (plasma chemical) methods. The one-stage method for producing composites involves the formation of filler structures during the burning of low-temperature plasma in the bulk of an aqueous polymer solution. Electrode materials were used as precursors. Regardless of the production method, 2D hexagonal structures are formed and embedded in the polymer matrix. This is evidenced by IR spectroscopy data showing shifts in the main characteristic bands and the appearance of new ones. It has been established that layered fillers can be both plasticizers and reinforcing agents. The influence of the viscosity of the polymer matrix on the mechanical characteristics of the composites has been revealed. The introduction of fillers changes the surface roughness, leading to an increase in hydrophobicity of the composites. It has been established that the current–voltage curves of the composites are nonlinear, so that such composites can be considered as flexible analogues of nonlinear electronic components.

The study of the electroluminescence of silicon vacancy color centers (SiV centers) in the diamond p-i-n diode at high current density of 500 A/cm2 is presented. To create color centers, the internal region of the diode was doped with silicon. In the electroluminescence spectrum, the bright emission line at 738 nm corresponding to the SiV color center in a negative charge state was observed. Such bright emission is due to high current density. Additionally, the 946 nm line corresponding to the emission of the color center in a neutral charge state was observed in electroluminescence. Nanosecond voltage pulses were applied to study electroluminescence in a pulsed regime. Short emission pulses at 738 nm were demonstrated, showing the potential of creating electrically driven single photon source with “photon on demand” capability. By comparing the intensities of photoluminescence and electroluminescence, the possibility of obtaining single photon emission rate in a diode exceeding 106 photon/s is shown.

The influence of methane plasma parameters on the deposition rate and on the content of the hydrogen and the sp3-carbon fraction in hydrogenated diamond-like carbon films (DLC) was investigated. It was shown that the proportion of the sp3-carbon fraction mainly depends on the inductive power and the argon addition to the plasma; the latter also contributes to a decrease of hydrogen in the films.

Ni–Al layered double hydroxides (LDHs) are of interest as functional materials. The effects of preparation methods on the dielectric properties of Ni–Al layered double hydroxides were studied on samples prepared from solution (by coprecipitation and a hydrothermal process) and by plasma technology. The prepared layered structures were characterized by advanced analytical methods. The high ζ potentials of the particles prepared in suspensions evidence their high aggregation stability. X-ray powder diffraction and IR spectroscopy were used to determine the phase composition of samples and to identify the interlayer anion. The plasma between Al and Ni electrodes in distilled bulk water gives rise to the formation of Ni–Al LDHs with hydroxide ion as the interlayer anion. Thermal properties of the structures prepared were studied by thermal analysis. The results of dielectric measurements are presented.

Hexagonal silicon polytypes have attracted significant attention within the scientific community due to their potential applications in next-generation electronics and photonics. However, obtaining stable heterostructures based on cubic and hexagonal polytypes is a challenging task. This study demonstrates the synthesis of thin layers of the hexagonal phase of silicon, specifically 9R-Si, using a conventional microelectronics technique—ion implantation. Implantation of Kr ^+ ions was performed through a SiO _2 layer, with thickness approximately twice the projected range of Kr ^+ ions, followed by high-temperature annealing. High-resolution transmission electron microscopy revealed that damage to Si substrate at the SiO _2 interface resulted in the formation of a thin amorphous layer, which recrystallized during annealing, leading to the formation of the 9R-Si polytype. It is presumed that mechanical stresses induced by implantation through the oxide layer promote hexagonalization during subsequent high-temperature annealing. The effectiveness of hexagonalization was found to depend on the substrate orientation. In addition to the formation of the 9R-Si phase, under the utilized implantation and annealing parameters, silicon exhibited light-emitting defects, with photoluminescence observed at a wavelength of approximately ∼ 1240 nm up to temperatures of about ∼ 120 K. The obtained results may find applications in silicon micro-, nano-, and optoelectronics.

A CuO–Cu 4 O 3 -based composite was synthesized in the combustion reactions of nitrate–organic precursors using various fuel additives (glycerol, citric acid, ovalbumin, and urea). The resulting powders were examined by X-ray phase analysis, scanning electron microscopy, and low-temperature nitrogen adsorption and tested as components of ceramics and photocatalysts. It was found that a change in the nature of the fuel additive does not lead to a change in the phase composition, but affects the specific surface area of the samples. A regularity between the particle size and the dielectric parameters of the obtained CuO + Cu 4 O 3 was revealed. It was established that all samples have photocatalytic activity towards the dye rhodamine B, and samples with a large specific surface area demonstrate high sorption property.

A technique is proposed for the formation of a developed regular structure on the surface of a polished single-crystal silicon wafer by ion-beam etching. It is shown that when single-crystal silicon is etched by a beam of accelerated Ar + ions with normal ion incidence on the sample surface, a surface region with a developed relief is formed, which can serve as a reflection-reducing layer. The reflection of radiation with wavelengths of 532, 633, 780, and 980 nm from a sample of single-crystal silicon with the orientation of the surface cut {100}, subjected to ion-beam treatment with Ar + ions with an energy of E ion = 400 eV for 10 hours (material removal was 7.5 µm) is studied. The specular-reflection curves of s -polarized radiation are obtained as functions of the angle of incidence. A decrease in the reflection coefficient relative to a polished silicon wafer is found at all investigated wavelengths. The largest decrease (more than 4 times) is recorded for a wavelength of 532 nm. It is shown that the range of heights of inhomogeneities formed during ion-beam etching increases linearly with an increase in the depth (time) of etching, which can be used to optimize the relief for a given wavelength.

In paper the influence of parameters of inductively coupled chloropentafluoroethane plasma on the rate and characteristics of gallium arsenide etching was studied. Etched GaAs profiles by white light interferometry and scanning electron microscopy were investigated. It turned out that the process rate does not depend on freon flow, but forward and inductive power, as well as pressure determined. In this case, when the power of the plasma generator increase, the surface morphology changes significantly, that manifests itself in roughness increase and the detection of defects on GaAs and mask. Carrying out a process at low pressure leads to the deposition of single large inhomogeneities on the substrate. The transition from pulsed to continuous etching is accompanied by deterioration in the anisotropy of a process due to the polymer layer deposition on side walls.

In paper the influence of parameters of inductively coupled chloropentafluoroethane plasma on the rate and characteristics of gallium arsenide etching was studied. Etched GaAs profiles by white light interferometry and scanning electron microscopy were investigated. It turned out that the process rate does not depend on freon flow, but forward and inductive power, as well as pressure determined. In this case, when the power of the plasma generator increase, the surface morphology changes significantly, that manifests itself in roughness increase and the detection of defects on GaAs and mask. Carrying out a process at low pressure leads to the deposition of single large inhomogeneities on the substrate. The transition from pulsed to continuous etching is accompanied by deterioration in the anisotropy of a process due to the polymer layer deposition on side walls. Keywords: chloropentafluoroethane, plasma-chemical etching, inductively coupled plasma, gallium arsenide.

The influence of thermal annealing on the transport properties of Ti/AlGaN/GaN low-barrier Mott diodes with near-surface polarization-induced δ-doping has been studied. It is shown that annealing provides additional possibilities for controlling the effective barrier height of diodes, improving and fine-tuning their transport characteristics. Thermal annealing can be used to fabricate low-barrier diodes designed to operate at high temperatures.

In this study, the dependence of the plasma-chemical-etching rate and the surface roughness of a gallium-arsenide crater on the concentration of chloropentafluoroethane (C2F5Cl) in a mixture with chlorine, the capacitive discharge power, and the etching duration are investigated. The characteristics of the GaAs etching crater are studied by white-light interferometry and scanning electron microscopy. It is shown that the addition of C2F5Cl into the chlorine-containing inductively coupled plasma leads to a nonlinear change in the gallium-arsenide etching rate with time, which can be explained by passivation of the substrate surface at the initial stage by the products of freon decay. Along with this, characteristics of the etching profile of GaAs are substantially improved. An increase in the capacitive discharge power promotes the development of roughness, while the etching rate increases nonlinearly.

All-epitaxial Al/AlxGa1−xN/GaN low-barrier Schottky diodes with different x compositions were fabricated in the single process of molecular-beam epitaxy. A decrease in the effective barrier height is achieved by polarization-induced δ-doping of the AlxGa1−xN/GaN heterojunction. At zero bias, the diodes have high values of ampere-watt sensitivity (7 A/W) with a low specific value of differential resistance (5 × 10−4 Ω⋅cm2) and retain non-linear properties when the resistance decreases to 10−4 Ω⋅cm2. The fundamental importance of the absence of impurities, oxides, and structural defects at the metal–semiconductor interface for effective control of the transport properties of diodes is demonstrated.

The influence of thermal annealing on the transport properties of Ti/AlGaN/GaN low-barrier Mott diodes with near-surface polarization-induced delta-doping has been studied. It is shown that annealing provides additional possibilities for controlling the effective barrier height of diodes, improving and fine-tuning their transport characteristics. Thermal annealing can be used to fabricate low-barrier diodes designed to operate at high temperatures. Keywords: low-barrier diode, GaN, transport properties, thermal annealing.

This paper summarizes the results of studying the creation of localized ensembles of NV centers in a single-crystal diamond. The diamond was doped with nitrogen during its CVD growth. Due to the use of a microwave CVD reactor, in which a rapid (a few seconds) change in the composition of the gas mixture is realized, thin (nanometer thick) doped diamond layers were obtained, the position of which relative to the substrate surface is known with high accuracy. The possibility of forming a matrix of NV centers localized on the crystal surface is demonstrated. The results of studying the fluorescence of NV centers in such structures are presented.

Ionogels are hybrid ion-conducting materials consisting of ionic liquids stabilized by inorganic or polymer fillers and having good prospects for application in solid-state and flexible electronics and energy storage devices. The work presents the results of studying the rheological properties and ionic conductivity of a series of ionogels based on halloysite nanoclay and bis(trifluoromethylsulfonyl)imide ionic liquids with EMIm+, BMIm+, BM2Im+, BMPyrr+, BMPip+ and MOc3Am+ cations and content of the dispersion phase of 43–48%. The obtained values are compared with the analogous characteristics of bulk ionic liquids. It has been established that the IL cation structural characteristics affect the viscoplastic properties of ionogels subjected to uniaxial quasistatic compression (20 °C), ionic conductivity and structural resistance coefficient of an inorganic filler (from −20 to +80 °C). Additive models of conductivity in binary systems are applied to obtain correlations linking ionic conductivity of ionogels with that of pure ionic liquids.

Crystalline composite structures based on titanium dioxide modified by magnetite particles with improved sorption and photocatalytic properties were obtained by a microwave-assisted method. This method is based on a polyol method synthesis of titanium glycolate using microwave heating and followed by the water treatment under microwave heating at 2.45 GHz, without using the calcination stage at high temperatures. It was found that the treatment of titanium glycolates in water under the influence of microwave heating leads to the formation of the crystal structure of titanium dioxide (polymorphic anatase modification). Using scanning electron microscopy, it was shown that during the synthesis of composite structures based on titanium dioxide, the formation of particles of a spherical and rod-shaped form. The resulting materials were characterized by electron microscopy, X-ray phase analysis, dynamic light scattering, and low-temperature nitrogen adsorption/desorption. The analysis of the influence of structural and morphological features on the adsorption capacity and photocatalytic activity of the composites is carried out. A comparative analysis of the photocatalytic activity of the obtained composites in the decomposition of the Rhodamine B dye under UV radiation showed that the most effective dye removal (~ 99 %) were observed in the presence of both spherical and rod-shaped composite structures as catalysts containing 1 % of magnetite.

In this work, the dependence of plasma-chemical etching rate and the roughness of the surface of gallium arsenide crater on chloropentafluoroethane (C2F5Cl) concentration in a mixture with chlorine, forward power and etching duration were studied. Characteristics of GaAs etching crater were studied by white light interferometry and scanning electron microscopy. It is shown that C2F5Cl addition in chlorine-containing inductively coupled plasma led to a nonlinear change of gallium arsenide etching rate with time which can be explained by passivation of substrate surface at the initial stage by products of freon decay. Along with this, characteristics of the etching profile of GaAs are significantly improved. Forward power increase contributes to development of roughness, while the etching rate increases nonlinearly.