A technology has been developed for manufacturing needle hydrophones with an active element made of vinylidene fluoride (VDF) copolymers with tetrafluoroethylene (TFE) and trifluoroethylene (TrFE), including a method for pretreatment of the needle surface to ensure high adhesion, continuity, and low roughness of the polymer coating. The surface treatment process involves electrochemical etching followed by nickel plating, which significantly improves the bonding between the polymer and the metal substrate. Piezoresponse force microscopy has confirmed the ability of the coatings to undergo effective poling without orientation stretching, which is critically important for deposition from solution directly onto the needle, as traditional stretching methods are difficult to apply in such a configuration. The proposed solution enables the creation of miniature hydrophones for calibrating medical ultrasound equipment and monitoring acoustic fields. The use of vinylidene fluoride copolymers provides improved acoustic matching with biological tissues compared to piezoceramic analogs, reducing signal distortion and increasing measurement accuracy. Consequently, the developed hydrophones represent a promising tool for clinical diagnostics and for ensuring the safety of ultrasound procedures.

A solution to the problem of resonant tunneling current saturation is proposed. This problem does not allow, within the traditional compact models, a correct qualitative and quantitative analysis to be carried out of the volt-ampere characteristics of double-barrier heterostructures. The reason for this problem is the asymptotic behavior of the function describing the structure transparency, so a non-saturating compact model was proposed to solve the problem of current transfer analysis in the region of negative differential conductivity. Validation of the proposed model confirmed its adequacy without losing the ability to analyze current transfer processes. This makes the developed compact model effective for simulating the operation of a wide range of devices with a resonant tunneling diode as a nonlinear element, regardless of the position of the operating point.

We investigated the optoelectric characteristics of transparent conducting structures of oxide/metal/oxide (OMO) type, where In2O3 is used as an oxide and Ag is used as a metal. Samples were obtained by magnetron sputtering. The focus is on the influence of the thickness and homogeneity of the silver layer on the optical and electrical properties of the structures. We use an ion etching method to improve performance of silver thin films and reduce thickness. Usually, in the case of poor wetting of the metal oxide substrate, the thin film grows by the island mechanism (Volmer–Weber mechanism), which leads to poor properties of the OMO structures. The proposed method consists of “thinning” the obvious continuous silver films using ion etching, because of which the thin silver films become closer to the films growing by the layer-by-layer mechanism (Frank–van der Merwe mechanism). The results obtained showed that ion etching allows us to achieve higher transparency of the structure without crucial loosing of electrical conductivity. This makes the method promising for further application in optoelectronic devices such as solar cells and displays.

Emerging technologies like the Internet of Things, printed and flexible electronics, and neural interfaces demand materials with exceptional properties. Laser processing offers a cost-effective and sustainable approach to creating conductive materials. We synthesized silver nanowires (AgNW) and used laser irradiation to enhance their properties. This led to sintering and partial melting of AgNW, significantly reducing sheet resistance. Furthermore, the laser melted the polymer interface, integrating AgNW and improving adhesion, allowing for flexible bending. The obtained high durable AgNW films on flexible polyethylene terephthalate (PET) substrate with low sheet resistance 0.03 Ω/sq and great mechanical stability. This making it suitable for flexible electronics applications.

The modern pace of scientific and technological development dictates unprecedented requirements for the speed of information transfer. The THz range is considered one of the most promising and has been actively developing in recent years. Along with the need to develop transmitting devices, the demand for shielding materials in this range, including transparent ones, is also growing. In this work, we present two types of composite films based on silver nanowires and PEDOT:PSS. We characterized these composite films in terms of optoelectrical parameters, as well as shielding characteristics in the THz range. We found that our composite films have a sheet resistance (R□) of about 8.6 ± 1.2 Ω/□ with a transparency of about 83.41 % and shielding efficiency is 25.85 dB in the THz region, which makes them excellent candidates for transparent shielding materials. We also made a bilayer sandwich structure from these composite films, which showed a shielding efficiency of about 49.34 dB in the range of 0.2–0.8 THz with a transparency of 66.33%. In addition, we assessed the possibility of real application of the structures in terms of stability to external conditions. Our composite films sustain atmospheric corrosion and maintain stable sheet resistance for 30 days.

Copolymers based on vinylidene fluoride are potential materials for ferroelectric memory elements. The trend in studies showing that a decrease in the degree of crystallinity can lead to an unexpected increase in the electric breakdown field is noted. An analysis of the literature data reveals that in fluorine-containing ferroelectric polymers, when using a bipolar triangular field, the hysteresis loop has an unclosed shape, with each subsequent loop being accompanied by a decrease in the dielectric response. In this work, the effect of the structure of self-polarized films of copolymers of vinylidene fluoride with tetrafluoroethylene and hexafluoropropylene on breakdown processes was studied. The structure of the polymer films was monitored using infrared spectroscopy (IR) and X-ray diffraction. Kelvin probe force microscopy (KPFM) was applied to characterize the local electrical properties of the polymers. For the films of the first copolymer, which crystallize in the polar β-phase, asymmetry in the dielectric response was observed at fields greater than the coercive field. For the films of the copolymers of vinylidene fluoride with hexafluoropropylene, which crystallize predominantly in the nonpolar α-phase, polarization switching processes have also been observed, but at lower electric fields. The noted phenomena will help to identify the influence of the structure of ferroelectric polymers on their electrical properties.

Nowadays, the Internet of Things (IOT), electronics, and neural interfaces are becoming an integral part of our life. These technologies place unprecedentedly high demands on materials in terms of their mechanical and electrical properties. There are several strategies for forming conductive layers in such composites, e.g., volume blending to achieve a percolation threshold, inkjet printing, lithography, and laser processing. The latter is a low-cost, environmentally friendly, scalable way to produce composites. In our work, we synthesized AgNW and characterized them using Ultraviolet-visible spectroscopy (UV-vis), Transmission electron microscopy (TEM), and Selective area electron diffraction (SAED). We found that our AgNW absorbed in the UV-vis range of 345 to 410 nm. This is due to the plasmon resonance phenomenon of AgNW. Then, we applied the dispersion of AgNW on the surface of the polymer substrate, dried them and we got the films of AgNW.. We irradiated these films with a 432 nm laser. As a result of the treatment, we observed two processes. The first one was the sintering and partial melting of nanowires under the influence of laser radiation, as a consequence of which, the sheet resistance dropped more than twice. The second was the melting of the polymer at the interface and the subsequent integration of AgNW into the substrate. This allowed us to improve the adhesion from 0–1 B to 5 B, and to obtain a composite capable of bending, with radius of 0.5 mm. We also evaluated the shielding efficiency of the obtained composites. The shielding efficiency for 500–600 nm thick porous film samples were 40 dB, and for 3.1–4.1 µm porous films the shielding efficiency was about 85–90 dB in a frequency range of 0.01–40 GHz. The data obtained by us are the basis for producing flexible electronic components based on AgNW/PET composite for various applications using laser processing methods.

The influence of technological variation of parameters of device design and their nonlinear elements on technological variation of frequency mixer assignment indicators has been investigated using the stochastic model of frequency mixers based resonant-tunnel diodes developed by the authors. The influence of various stages of the diodes' manufacturing process on the scatter of the mixer assignment indicators has been assessed. The total contribution of technological scatters of the resonant-tunneling diodes' design parameters to the technological scatters of the studied mixers' performance indices (conversion losses, the level of unwanted combinational components of the output spectrum of the signal, the upper limit of the dynamic range by 1dB compression and intermodulation) is about 90%, and the largest contribution to the technological dispersion of the mixers' performance indices is caused by technological errors of the diodes' active region forming operations; the second place belongs to technological errors of the diodes' topology forming operations.

Developing new environmentally friendly methods of producing materials for electronics is critical important task for material science. Manufacturing process of semiconductor materials, transparent electrodes, electrical and thermal conductive pastes, fillers for conductive inks and some other materials should be improved from environmental point of view. Here we present a waste-free closed cycle fabrication of two important materials for electronics based on the concept of a self-organized cracked template. Optically transparent silver meshes and silver microflakes were obtained in waste-free manufacturing cycle. The morphological, structural, optoelectric, and shielding properties of transparent silver meshes and silver microflakes films were studied in detail. Also, we made transparent heater in close manufacturing cycle. The first type of materials are transparent silver meshes with irregular structure that have a transparency of more than 80

This paper describes a novel approach to imaging polypropylene PP using digital inkjet printing techniques. The low surface energy of PP, and significant hydrophobic properties prevent it from being used for direct coloration by available methods. A number of surfactants (surfactants) have been proposed as pre-coatings to improve the adhesion between the polymer surface and the ink. Due to the amphiphilicity of surfactants, improved coloration and enhanced color rendering are provided. The polymer/surfactants interactions were evaluated by IR spectroscopy. The amount of surfactants was evaluated using TGA analysis. The effect of modifying agent concentration was evaluated using wetting edge angle measurement. The surface morphology was evaluated using scanning electron microscopy. The test scales were printed and their colorimetric performance was investigated. The study demonstrates the high potential of surfactants for tuning the properties of nonwoven polymeric materials.

Changes in the composition of the surface layer of Nevaflon polyvinylidene fluoride film after treatment in gas discharges of various types (glow, dielectric barrier, corona) have been studied. The influence of the discharge type on the kinetics of etching and surface modification of polyvinylidene fluoride is shown. It has been found that the plasma treatment of polyvinylidene fluoride leads to a change in the modified surface layer of the polymer.

Subject of study. The study focuses on an acousto-optical modulator composed of a polyvinylidene fluoride film with transparent indium-tin oxide electrodes deposited on both surfaces. Aim of study. The aim is to analyze the stability of the mechanical, piezoelectric, and optical properties of the polyvinylidene fluoride film-based acousto-optical modulators with indium-tin oxide electrodes during manufacturing and operation at different temperatures. Method. In this method, the mechanical characteristics of samples under tension are measured along two directions (parallel and perpendicular to the drawing direction of the polyvinylidene fluoride film) at room temperature to perform a dynamic mechanical analysis under isothermal conditions and within a temperature range of 30 degrees C-180 degrees C. The piezoelectric coefficient d 33 is measured, under temperature variation from - 40 degrees C to + 80 degrees C, using a charge-based method with pulsed force impact, and the transmittance is determined within the visible wavelength range from 380 nm to 780 nm to calculate the light transmission coefficient. Main results. An experimental measurement cell was created to measure the piezoelectric coefficient d 33 across a wide temperature range. Mechanical test results for static and dynamic loading of the polyvinylidene fluoride film, both before and after the deposition of the indium-tin oxide electrodes, were obtained. Temperature dependencies of d 33 for this structure were established from - 40 degrees C to + 80 degrees C, and the optical properties of the samples exposed to low and high temperatures were documented. Practical significance. Based on these findings, recommendations for the operating and storage conditions of acousto-optic devices incorporating the studied structures, along with guidelines for manufacturing, are presented. (c) 2024 Optica Publishing Group

The impact of indium doping percentage in resonant-tunneling diode's spacer layer on the diode's current-voltage characteristic was assessed by the means of computer modeling. The previously developed resonant-tunneling diode's physical and topological model has been supplemented with the parameters required for diffusion processes modeling in the active region of the diodes with InGaAs spacer layers. It is shown that with 20% substitution of gallium by indium in the studied resonant-tunneling diode's spacer layers, the peak current of the current-voltage characteristic's initial section increases approximately by 5 times, the peak voltage - approximately by 2 times. The peak current's and peak voltage's dependencies on the indium doping percentage in the resonant-tunneling diode's spacer layers were obtained. From the results of the study, it was concluded that it is promising to include the resonant-tunneling diode's spacer layers' chemical composition in the controlled parameters of the diode's design parameters optimization to achieve the required electrical characteristics.

Using a self-organized template made by cracking a thin film of egg white, effective irregular aluminum mesh transparent conductor (Al MTC) is obtained. The resulting Al MTCs are characterized by a sheet resistance of 12.26 Ω/sq, while the transmittance in the visible region is 83.15%. Transmission and reflection coefficients for Al MTC in the microwave range, 0.7-14 GHz, were measured using an antenna stand with horn antennas. It is shown that irregular Al MTC has an excellent combination of optical transparency, more than 83%, and shielding efficiency (SE) of more than 25 dB in the range of 0.7-14 GHz. At the same time, it is resistant to bending and compression deformations, in contrast to standard ITO coatings on flexible substrates.

This paper presents a comparative analysis of diamond-like carbon (DLC) coatings deposited by different methods using Raman spectroscopy and atomic force microscopy (AFM). The unique combination of high hardness and chemical resistance in DLC coatings makes them particularly valuable for advanced optoelectronic devices and precision instrumentation, where these properties enhance device longevity and operational efficiency. The paper examines coatings deposited by hollow-cathode-enhanced magnetron sputtering, pulsed laser deposition (PLD), and cathodic arc deposition with laser ignition of carbon plasma and plasma flow separation (CAD-LICPFS) is used to determine structural features, such as crystallinity and the distribution of sp 3 and sp 2 hybridizations. The AFM method allows one to study the surface morphology and evaluate the surface topography of the coatings. The results of the studies show that the deposition method significantly affects the structure and properties of DLC coatings. The obtained data provide valuable insights for optimizing deposition processes to produce high-quality DLC coatings for various industrial applications.

Polypropylene is a widely used polymer material with good mechanical strength and chemical resistance. However, its low free surface energy limits the possibilities for post-production staining, especially when applying coatings and images.In this work, experiments were carried out to modify polypropylene nonwoven fabric (spunbond) using sodium lauryl sulfate (SDS) in various concentrations. The following methods were used for characterization: optical microscopy was used to study surface morphology, analysis of contact angles to determine hydrophilicity, differential scanning calorimetry to assess the interaction of surfactants and polypropylene, as well as tests for breathability and image resistance to water. The results show that the modification of polypropylene SDS increases the hydrophilicity of the material, which improves adhesion to pigment inks and, therefore, makes it more suitable for digital inkjet printing. It has been found that a high concentration of SDS can reduce the breathability of the material, but this is not a critical limitation for most practical applications.The study demonstrates that the use of surfactants, especially in low concentrations, is an effective and economical method of modifying the PP surface, providing the necessary hydrophilicity and resistance to leaching, without significantly deteriorating the mechanical properties and visual characteristics of the material.

The influence of diffusion processes occurring in spacer layers, active region layers and reservoirs of the resonant-tunneling diodes’ heterostructure on the dopant concentration in the near-contact regions and the active region layers’ and spacers’ heterojunctions blurring is investigated. The previously developed mathematical model of resonant tunneling diodes is extended with relations allowing to simulate indium diffusion from the spacer layers into the barrier layers and near-contact regions. The dopant’s penetration depth into the spacer layers, as well as aluminum from the barrier layers into the well and spacer layers, is estimated, based on which recommendations are developed for the minimum thickness of the spacer layers. It is shown that diffusion processes occurring in the heterostructure of diodes at the operation stage do not affect the dopant concentration profile in the near-contact regions and do not change the profile of the conduction band bottom of the active region of the diode.

This work investigates the structural and electrophysical properties of films of vinylidene fluoride-tetrafluoroethylene copolymer (VDF/TFE) derived from xerogel. Materials produced in this manner have a porous structure with unique properties. The high values of pyroelectric and piezoelectric response, as well as the chemical and thermal stability of VDF/TFE, make the polymer promising for various engineering applications, including flexible electronics materials, particularly for creating sensors, actuators, and energy storage devices. Films made from the melt or solution using traditional methods require subsequent processing to acquire ferroelectric properties, such as stretching, isothermal annealing, and polarization. The production of films from xerogel can potentially reduce the technological process of creating ferroelectric materials with an ordered structure. It has been shown that VDF/TFE xerogel films possess sufficient crystallinity, an ordered structure, and high lateral piezoelectric response values.

a silver irregular micromesh transparent conductors with excellent combination of optoelectric characteristics have been obtained in this work. Broadband measurements of EMI shielding properties irregular mesh transparent conductor have been carried out. It is shown that in the high-frequency region the shielding ability reaches saturation and becomes indistinguishable for 600 nm and 1000 nm thick silver mesh transparent conductors. As expected, the key factor for mesh transparent conductor coatings is the average cell size, which turns out to be the limiting factor for shielding at high frequencies. The experimental data are in agreement with the Kantorovich model.

The problem of ensuring the operational parameters of composite multilayer semiconductor nanoscale structures at the design technology stages is solved. A mathematical model based on the physics of processes occurring in the structure during operation is developed. The problem is solved for the resonant-tunnelling AlGaAs nanoheterostructures.