To achieve high characteristics of single-photon detectors based on WSi thin films it is necessary to provide high film thickness uniformity more than 95%. This paper presents a mathematical modeling of the thickness uniformity of an ultra-thin film formed by magnetron sputtering from two sources, based on an experimentally determined mass flow from a single magnetron, depending on the location of the magnetrons relative to the substrate holder. According to the results of non-uniformity modeling, the requirements for the design and location of the magnetron unit in the chamber were made, which ensured the required non-uniformity of the film thickness of less than 5%.

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°C–180°C. The piezoelectric coefficient d₃₃ is measured, under temperature variation from −40^∘C to +80^∘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 d₃₃ 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 d₃₃ for this structure were established from −40^∘C to +80^∘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.

Glow-discharge plasma (GDP) poling is revisited as an electrode-free method for activating piezoelectricity in poly(vinylidene fluoride) (PVDF) films. Although this method was proposed several decades ago, its effect on the properties of PVDF films has remained poorly understood. In this work, we demonstrate that GDP enables efficient poling of oriented PVDF films without pre-deposited electrodes and investigate the relationship between plasma treatment time, structural evolution, and piezoelectric response. Commercially available 25 μm-thick oriented PVDF films (PolyK) were treated in a DC glow discharge for 15 s to 15 min and characterized using FTIR, DSC, piezoresponse force microscopy, UV–Vis–NIR spectrophotometry, quasi-static d₃₃ measurements and water contact-angle measurements. GDP poling produced a side-averaged piezoelectric coefficient d₃₃ of up to ~25 pC/N within 1–5 min, with local maxima at approximately 1, 2.5, and 5 min. This behavior was accompanied by pronounced changes in the domain structure, including an increase in the ferroelectric domain size from 86 to 552 nm, while the crystallinity and electroactive phase fraction changed only moderately. Plasma treatment also increased the wettability of the plasma-facing surface, reducing the water contact angle from about 85° to 42° within 3 min. At longer treatment times (>5 min), however, the piezoelectric response decreased and the optical transparency deteriorated because of increased haze and turbidity, most likely associated with plasma-induced chemical modification of the surface layers. These results indicate that GDP poling has an effective processing window of 1–5 min. The proposed approach provides a vacuum-compatible and electrode-free route for preparing PVDF films with increased surface wettability for flexible piezoelectric sensors, wearable electronics, and integrated polymer-based devices, because it is compatible with electrode deposition on an already activated polymer surface within a single vacuum cycle.

В работе описаны актуальные модели детектирования и текущее состояние развития техники однофотонных детекторов. Проведен анализ материалов изготовления ультратонких пленок для детекторов, структура которых создана на основе полосок микрометровой ширины (SMSPD), и составлены рекомендации для улучшения их рабочих характеристик. Для снижения скорости темнового счета (DCR), возрастания эффективности детектирования системы (SDE), быстродействия (CR) и увеличения активной площади необходимо использовать SMSPD из рентгеноаморфных материалов типа α-Mn с низким коэффициентом диффузии, обладающих топологией, созданной на основе брэгговских отражающих структур (DBR), с высоким коэффициентом заполнения и уширением полосы элементов на повороте.

An experimental investigation of the structure and phase composition by X-ray, Raman, and ultrasoft X-ray emission spectroscopy, as well as the study of the electrical properties of WxSi(1-x) films used as sensitive elements of superconducting single-photon detectors (SNSPD), depending on the thickness in the range from 7 to 80 nm, was carried out, according to the results of which it was found that the W3Si phase is presumably formed in films 20 and 40 nm thick with a resistivity of 8.4 10-5 and 6.0 10-5 Ω cm, respectively, containing the WSi2, W5Si3, and SiO2 phases, as well as WOx and a small share of β-W. Films with a thickness of 7 nm have the highest resistivity of 18.0 10-5 Ω·cm and contain nanocrystals, WSi2, SiO2, as well as β-W, and an amorphous silicon phase. Films with a thickness of 80 nm (the resistivity is also 18.0 10-5 Ω·cm) predominantly contain WSi2, as well as W5Si3 and SiO2, and, presumably, the W3Si phase.

Introduction. A review of foreign publications on 3D printing methods shows the possibility of their application for the manufacture of printed circuit boards (PCBs), while demonstrating the growth of interest in this field. One of the available methods is fused deposition modeling, which can be used to form substrates with channels for traces. At present, the minimum channel width comprises 100 µm, which corresponds to the 5th class of PCB accuracy. However, there is no data on how to obtain such dimensions or on the magnitude of their deviation from the given nominal values.Aim. To determine the influence of such factors as nozzle diameter and the number of contours on the dimensional characteristics of PCBs (linear dimensions; trace channel width; trace spacing; via diameters).Materials and methods. To obtain linear models, a full factorial experiment was carried out. The influence of the following materials was evaluated – polylactide (PLA), acrylonitrile butadiene styrene (ABS) and glass-filled ABS; slicers – Ultimaker Cura and PrusaSlicer; 3D printers – Picaso 3D Designer Classic 2016 and Hercules Strong 2017; brass nozzle with diameters ∅0.2 and ∅0.4 mm. The possibility of using brass nozzles coated with chemical nickel for printing with glass-filled filaments was considered. The study was conducted using the facilities of the "Center for Additive Technologies" of Bauman Moscow State Technical University.Results. The possibility of manufacturing PCBs up to the 2nd and 3rd accuracy classes using nozzles with a diameter of ∅0.4 and ∅0.2 mm, respectively, was shown. It was found that galvanic deposition of chemical nickel on a ∅0.2 mm brass nozzle makes it possible to increase the PCB wearability when printing with glass-filled filaments. Recommendations are proposed for selecting an optimal combination of nozzle diameter and the number of contours.Conclusion. The conducted analysis of mathematical models shows the significance of such parameters as nozzle diameter and the number of contours. The results can be used when creating new PCB layouts