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PURPOSE. The main goal of the research, the results of which are presented in the article, is to develop the method of determining optimal time required for professional training of fire-rescue units chiefs. In the given article incompetence refers to the state of professional and personal qualities of students (trainees) that characterizes the complete or partial lack of knowledge, abilities, skills, and experience in performing certain type of practical activities. It is assumed that the optimal time of training can be less than the amount of time currently spent without analytical or statistical assessment of the expediency of its spending. METHODS. As a mathematical apparatus, mathematical methods of reliability theory have been applied, as well as methods of probability theory and mathematical statistics. To prove the method feasibility numerical experiment has been carried out. FINDINGS. The presented method makes it possible to determine the minimum necessary time for a student (trainee) to master the required amount of managerial competence and develop firm professionally relevant qualities. To prove the method feasibility numerical experiment has been carried out. RESEARCH APPLICATION FIELD. The research results can be applied for improving teaching process for fire-rescue units chiefs as well as for heads of other organizational structures. CONCLUSIONS. The developed method makes it possible to establish the asymptotic dependence that shows the reduction of relative incompetence in a certain type of management performance depending on the time spent on study. A lemma has been proved about a point on function graph of dependence of relative incompetence on time corresponding to the optimal level of incompetence reduction and learning time.

Oxidation behavior of a-SiC:H layers deposited by radio-frequency magnetron sputtering technique was examined by Kelvin probe force microscopy (KPFM) in combination with scanning electron microscopy, Fourier-transform infra-red spectroscopy and submicron selected area Raman scattering spectroscopy. Partially oxidized a-SiC:H samples (oxidation at 600 °C in oxygen) were examined to clarify mechanism of the oxidation process. Nanoscale and microscale morphological defects (pits) with dimension of about 50 nm and several microns respectively have appeared after thermal treatment. KPFM measurements exhibited the surface potential of the material in micro pits is significantly smaller in comparison with surrounding material. Submicron RS measurements indicates formation of graphite-like nano-inclusions in the pit defects. We conclude that initial stage of oxidation process in a-SiC:H films takes place not homogeneously throughout the layer but it is initiated in local nanoscale regions followed by spreading over all layer.

In this study, we report on the feasibility of formation of nickel/tin solder pads and bus bars directly electroplated onto the aluminum screen-printed rear metallization layer of silicon-based solar cells. A localized wet processing technique via dynamic liquid drop/meniscus is used to perform the electrodeposition procedure. Excellent mechanical and electrical parameters of electroplated contacts are measured, thus proving the reliability of the proposed approach suitable for industrial application. Adhesion of electroplated nickel/tin solder pads is ensured through a two-step electrochemical pretreatment procedure, resulting in mean peel force values ranging from 2.5 to 3.8 N/mm. Electroplating of solder pads directly onto the screen-printed aluminum layer allows us to obtain a full homogeneous back surface field on the solar cell, resulting in an efficiency gain in 0.31–0.48% abs range. Furthermore, the proposed method completely removes the need for silver in the rear-side metallization layer of silicon-based solar cells.

We have optimized the procedure for preparation of nanostructured silver films on the surface of mesoporous silicon (PSi) to use them as active substrates in surface-enhanced Raman scattering (SERS) spectroscopy. The greatest enhancement of the SERS signal was observed for samples obtained when the silver was deposited on PSi from an aqueous AgNO3 solution with concentration 1⋅10–2 M over a 10–15 minute period. The detection limit for rhodamine 6G on SERS-active substrates prepared by the optimized procedure was 1⋅10–10 M. The enhancement factor for the SERS signal on these surfaces was estimated as ≈2⋅108. We have shown that SERS-active substrates based on mesoporous silicon are promising for detection and study of complex organic compounds, in particular tetrapyrrole molecules.

31st European Photovoltaic Solar Energy Conference and Exhibition; 226-229, We developed a new architecture of crystalline solar cell, based on an ultrathin silicon membrane, taking advantage of the technology of porous silicon. The architecture consists of a macro-porous membrane, offering deeply textured surface, capable to efficiently capture the impinging light, absorbed it in the porous structure, and delivering the photo-generated carriers to contacts deposited at the extreme of the ultra-thin semiconductor layer. The new method of realization of the ultra-thin cut from a silicon wafer, is based on the possibility to etch macroporous structures at the silicon surface, by using the proper regime, to obtain nano-porous etching underneath it, and from this obtain very thin membrane. The cell was measured in dark and light condition. The rectifying junction appears as not jet optimized, nevertheless the cell showed a very large current collection under AM1.5G, evidence of the excellent scattering process induced by the porous structure, and of the optimal passivation achieved.

In this paper, a two-layer metallization for silicon based solar cells is presented. The metallization consists of thin nickel barrier and thick copper conductive layers, both obtained by electrodeposition technique suitable for phosphorus-doped 70-90 Ω/sq solar cell emitter formed on p-type silicon substrate. To ensure the adhesion between metal contact and emitter a very thin layer of mesoporous silicon is introduced on the emitter surface before metal deposition. This approach allows metal anchoring inside pores and improves silicon-nickel interface uniformity. Optimization of metal contact parameters is achieved varying the anodization and electrodeposition conditions. Characterization of contacts between metal and emitter is carried out by scanning electron microscopy, specific contact resistance and current-voltage measurements. Mechanical strength of nickel-copper contacts is evaluated by the peel test. Adhesion strength of more than 4.5 N/mm and contact resistance of 350 μΩ cm2 on 80 Ω/sq emitter are achieved. © 2015 Elsevier B.V. All rights reserved.

A new approach based on the development of a new low-cost masking material and a new technique for performing fast wet processes (i.e. chemical etching and electroplating processes) are presented, back side silver removal is proposed allowing in combination with a multi-bus bar module assembly technique to boost standard silicon solar cells towards higher efficiencies at low cost. The new masking material based on a low-cost wax is able to withstand wet hot chemical treatment up to 100 °C. The developed wax composition that costs 10 times less than photoresist can be taken into consideration as an industrial masking process for solar cell for the front copper metallization process. However, the industrial applicability of the copper plating processes foresees several issues concerning the cell throughput for the plating technique at industrial level, which is directly connected to the plating speed. In this work, it is shown how using the new concept of coalescent dynamic liquid drop/meniscus is possible to plate 35 μm thick copper fingers on wax masked solar cell with a deposition speed as high as 1 μm/s. Combining the proposed technique with the back side selective plating, a silver-free silicon solar cell fabrication process is developed allowing to reach efficiencies higher than 18 % for monocrystalline silicon solar cell. © 2015 IEEE.

In this work we report the application of the selective wet processing technique based on dynamic liquid meniscus for copper pillar bumps (CPB) plating. The industrial plating of copper for CPB process is typically carried out at 2 μm/min. A much higher copper deposition rate is necessary to improve throughput for this process. To achieve higher deposition rates of copper the hydrodynamic issue that is natural for all conventional plating baths processes must be solved. A number of solutions is proposed towards realization of high speed and high throughput CPB plating process. Uniformity of copper pillar over a 6-inches silicon wafer is presented and the morphology and shapes of pillars are investigated by scanning electron microscopy (SEM). Copper pillar height and dimension are investigated within different topology over the wafer showing the robustness of the process for the thickness uniformity. Preliminary investigation of the CPB plating shows the uniformity of better than 2 % within 6” silicon wafer.

Low cost concept based on the porous silicon technology is shown to be well suitable for integrating monolithically the photonic devices on a standard silicon wafers by using localized SOI structures fabricated by electrochemical anodization of silicon wafers followed by thermal oxidation of porous silicon. The new approach consists in realizing buried localized porous oxidized silicon by exploiting two different routes: n - epi/n + /n - structures on p-type wafers and ion-implantation on standard CMOS/BiCMOS wafers. The peculiarities of the developed approach, including anodization and thermal oxidation regimes to form oxidized porous silicon regions with the required properties are presented. The advantages of the proposed approach in realizing the fiber-to-chip and power-over-fiber coupling are discussed.

In this work we demonstrate a new selective metallization technique to perform localized plating on the screen-printed Al contact using the innovative approach based on Dynamic Liquid Drop/Meniscus that is able to touch the cell back contact in specific defined positions and show that it is possible to produce suitable electrical and mechanical contact with Al-Si and thus to replace the silver from the back contact in the cell manufacturing process reducing the solar cell cost. A fast pre-treatment process was developed to clean and prepare the surface of the aluminum on the back side of PV cells allowing direct plating with good electrical contact. Several commercial aluminum screen printable pastes have been experimented also having different distribution of sphere particles dimensions. We have used high resolution Scanning Electron Microscopy (SEM) and compositional microanalysis with Energy Dispersive X-Ray microanalysis (EDX) to evaluate the metal dispersion within aluminum-silicon inter-diffused region and Transfer Length Method and current-voltage measurements to estimate the specific contact resistivity of the metal contact and series resistance of the overall solar cell device. We have found that the interconnection ribbon soldered on tin contacts plated on screen printed aluminum back contact shows adhesion higher (> 1N/mm) than that verified on screen printed silver over silicon. The main difference between a tin pad and a nickel-tin pad will be shown. Efficiency increase and fill factor are compared respect standard Al-Ag back contact PV cell.

A new selective processing technique based on a confined dynamic liquid drop\meniscus is presented. This approach is represented by the localized wet treatment of silicon wafers using dynamic liquid drop that while is in contact with the wafer forms a dynamic liquid meniscus. The main scientific innovation and relevance introduced by this work have been applied to industrial solar cell production and on silicon wafer metal bumps formation for the IC interconnection (i.e. copper pillars). Such new technique allows to touch in specific defined positions the silicon wafer in order to perform any kind of wet processing (e.g. etching, cleaning and/or plating) without the need of any protective resist. To investigate on pendant dynamic liquid drops and dynamic liquid meniscus use of computational fluid dynamic technique (i.e. numerical techniques to accurately predict fluid flows) was followed and is presented. An experimental setup has been built to validate the calculations. Numerical results showed a good agreement with experimental ones. Prototypes heads, using stereo-lithography systems, were developed and localized selective plating without the need of lithography step was performed on silicon.

In this work we present a new design for a three-dimensional vibration energy harvester, which is made by Micro-Electro-Mechanical Systems (MEMS) technology, and which can convert electric energy through transverse mode piezoelectric effect. The presented power generator is based on a long, thick-film, piezoelectric beam configured as a conical helix structure and located between two metal electrodes. The design of the combined antenna/energy harvester (comvester, from communication and energy harvester) device addresses both electromagnetic and mechanical issues as it radiates electromagnetic energy and converts mechanical energy into electric energy. Both functions are translated directly into dimensional constraints of the structure. In this work, we concentrate on millimeter waves communications in the 60 GHz frequency band because of their availability for low-power CMOS radio circuits. In order to realize comvester on a silicon wafer we used Controlled Release Metal Layer (CRML) technology, which is a transfer layer technology that uses porous silicon as sacrificial material. The advantage of CRML technology is high repeatability and resolution and its compatibility with back-end of line processes of the integrated circuit industry. New type of piezoelectric material consisted of the array of separated vertical polyvinylidene fluoride (PVDF) microrods is suggested. Such periodic microrods structure became possible to realize using the template of the structured macroporous silicon.

In this work we propose a detailed investigation of the Al - Si interdiffusion that occurs during the firing process of the Al-Si back contact of silicon based solar cells. The investigation is based on high resolution scanning electron microscopy (SEM) and compositional microanalysis with energy dispersive X-Ray microanalysis (EDX). We have found a dependence of Si precipitation in the Al matrix depending on the microstructure of the Al screen printable paste. We suggest a gettering effect promoted by the larger Al particles lying within the Al paste being able to affect the Al paste resistivity, the Al distribution within the BSF region of the solar cell, thus affecting the solar cell performances and finally the Al paste thermal expansion coefficient. Finally we demonstrate that the presence of the glass frit reduces the surface tension and, homogenizes the diffusion process. Reduction of surface tension decreases the internal pressure and increases the Si interdiffusion in Al. © 2013 The Authors.

Electroporation is an effective method to deliver drugs into tumor cells to kill them, by applying a pulsed electric field to the cellular membrane. Existing electrodes consist of clamping claws or arrays of needles and can be effectively applied only to small areas. New electrodes that can treat large areas are sought; flexibility is needed to adapt to irregular tumor shape and, to be folded to enter from small surgical opening. In this work we present the design and test of a 16 cm2 flexible electrode for electroporation with biosensing capabilities, built with standard flexible circuit technologies enclosed in a biocompatible package. The electrode contains electronics to provide cryptography-based identification to the electroporation machine to avoid setup errors and protection against use of counterfeited electrodes. In-vitro tests of the electrode show that electroporation occurs up to a depth of 8 mm with 100% electroporation efficiency over the 30% of electrode area. Temperature rise on the electrode during treatment does not exceed 6 degrees celsius, a value that not causes damage to the cells.

A new selective processing technique based on a confined dynamic liquid drop\meniscus is presented. This approach is based on localized wet treatment of silicon wafers using confined and dynamic liquid drop that while in contact with the wafer forms a dynamic liquid meniscus. Such new technique allows to touch in specific defined positions the silicon wafer (front and/or back) in order to perform any kind of wet processing without the need of protective photo-resist. The new selective processing technique allows the metallizations (front and back) of mono and multi crystalline silicon solar cells. The front grid contacts are obtained by locally etching the silicon nitride, forming in a thin layer of meso-porous silicon and totally filling the meso-porous layer by pulse reverse plating a Nickel film. Copper and Tin are then electroplated using the same selective processing. This technology provides an effective solution to avoid silver pastes for front contact grid, as it guarantees low specific contact resistivity (550 μΩcm2 on a 75 Ω/□ n-type doped emitter) and good adhesion to the silicon substrate (i.e. greater than 550 g/mm). The Al back side of the solar cell are also treated by the new selective process. Tin is directly deposited on Aluminum back contact showing adhesion higher than silver on silicon (i.e. > 1N/mm). © 2013 The Authors.

Porous silicon layers were produced by electrochemical etching of single-crystal silicon wafers with the resistivity 10 Ω cm in the aqueous-alcohol solution of hydrofluoric acid. Raman spectroscopy and infrared absorption spectroscopy are used to study the processes of interaction of porous silicon with undiluted acetylene at low temperatures and the processes of oxidation of carbonized porous silicon by water vapors. It is established that, even at the temperature 550°C, the silicon-carbon bonds are formed at the pore surface and the graphite-like carbon condensate emerges. It is shown that the carbon condensate inhibits oxidation of porous silicon by water vapors and contributes to quenching of white photoluminescence in the oxidized carbonized porous silicon nanocomposite layer.

Platinum nanoparticles supported on porous silicon were synthesized by radiation-chemical reduction in solutions of reverse micelles. The Pt nanoparticles obtained are electrondeficient. The degree of porosity, conductivity type, pore geometry of the silicon matrix, and precursor parameters affect the size, shape, and charge state of the platinum catalysts.

Porous silicon (PS) prepared from n-type Si crystal is proposed as a new material for the fabrication of sensitive substrates for surface-enhanced Raman scattering (SERS). The formation procedure for nanostructured silver films on the surface of PS was optimized. Maximum of SERS enhancement for rhodamine 6G probing molecule is observed for samples obtained by the immersion plating from the water solution of AgNO 3 with the 10 mM concentration during 5 min. The dependence of morphological parameters of PS and corresponding silvered surfaces on the anodization current density has been studied. It is shown that the most SERS activities possess substrates produced from PS with lower porosity. The optimum of the PS layer thickness for high Raman signal is about 5 μm. The detection limit for rhodamine 6G adsorbed on Ag-coated PS from the 100 pM solution is established to be comparable with that for p-type PS-based substrates. Thus, the n-type porous silicon is suitable material for the preparation of sensitive SERS-active substrates.