Silicon Metal Research Articles

Physics of Failure (PoF) Based Lifetime Prediction of Power Electronics at the Printed Circuit Board Level

This paper presents the use of physics of failure (PoF) methodology to infer fast and accurate lifetime predictions for power electronics at the printed circuit board (PCB) level in early design stages. It is shown that the ability to accurately model silicon–metal layers, semiconductor packaging, printed circuit boards (PCBs), and assemblies allows, for instance, the prediction of solder fatigue failure due to thermal, mechanical, and manufacturing conditions. The technique allows a life-cycle prognosis of the PCB, taking into account the environmental stresses it will encounter during the period of operation. Primarily, it involves converting an electronic computer aided design (eCAD) circuit layout into computational fluid dynamic (CFD) and finite element analysis (FEA) models with accurate geometries. From this, stressors, such as thermal cycling, mechanical shock, natural frequency, and harmonic and random vibrations, are applied to understand PCB degradation, and semiconductor and capacitor wear, and accordingly provide a method for high-fidelity power PCB modelling, which can be subsequently used to facilitate virtual testing and digital twinning for aircraft systems and sub-systems.

Reactivity assessment of charcoal for use in silicon production

As charcoal is used in the silicon metal process, reactivity towards SiO is one of the most important properties that has strong effects on silicon recovery. The purpose of this study was to analyze anatomical properties of wood and charcoal, define a procedure to express the SiO reactivity in a simpler and more cost-efficient manner and indicate one or more clones of Eucalyptus with the greatest potential for production of charcoal to silicon use. Three hybrid clones of Eucalyptus urophylla × Eucalyptus grandis were used for the study and the coke was investigated for comparison purposes. Morphological analysis of fiber and vessels was carried out in wood, and the fiber wall area was determined on charcoal. The number of reactivity was calculated in five different protocols, based on the SiO reactivity test. To classify the charcoal with the greatest potential for silicon use, the parameter Readily Available Fixed Carbon Stock was created, based on charcoal`s most important properties. All charcoals had significantly higher SiO-reactivity than coke. In addition, an increasing trend of charcoal SiO-reactivity was found with decreasing wood basic density, apparent density and fiber wall area of charcoal, which are connected to porosity. All the reductant materials presented similar readily available fixed carbon stock. The developed procedure used for SiO reactivity measurements was a useful tool to classify charcoal for use in the silicon production process.

THz linear array scanner in application to the real-time imaging and convolutional neural network recognition

Room temperature linear arrays (up to 160 detectors in array) from silicon metal- oxide-semiconductor field-effect transistors (Si-MOSFETs) have been designed for sub- THz (radiation frequency 140 GHz) close to real-time direct detection operation scanner to be used for detection and recognition of hidden objects. For this scanner, the optical system with aspherical lenses has been designed and manufactured. To estimate the quality of optical system and its resolution, the system modulation transfer function was applied. The scanner can perform real-time imaging with the spatial resolution better than 5 mm at the radiation frequency 140 GHz and contrast 0.5 for the moving object speed up to 200 mm/s and the depth of field 20 mm. The average dynamic range of real time imaging system with 160-detector linear array is close to 35 dB, when the sources with the output radiation power of 23 mW (IMPATT diodes) are used (scan speed 200 mm/s). For the system with 32-detector array, the dynamic range was about 48 dB and for the single-detector system with raster scanning 80 dB with lock-in amplifier. However, in the latter case for obtaining the image with the sizes 20×40 mm and step of 1 mm, the average scanning time close to 15 min is needed. Convolutional neural network was exploited for automatic detection and recognition of hidden items.

Mechanism investigation on effects of glass composition on Ag/Si contact for crystalline silicon solar cells

Pb–Te–Li oxide glasses have been widely applied in front silver (Ag) paste metallization of crystalline silicon (c-Si) solar cells. In practical application, some other important glass compositions, such Bi2O3, SiO2, ZnO and so on, are often added into Pb–Te–Li oxide glasses to improve the quality of Ag/Si contact. In this paper, the significant effects of these glass compositions on the Ag/Si contact are demonstrated by discussing their influences on the formation of Ag colloids in the interface, the erosion of glass to Si, the glass phase conductivity, and the glass passivation performance at the contact interface. The results show that the addition of Bi2O3 or SiO2 into the glass may reduce the Ag/Si contact resistivity, because Bi2O3 can promote the formation of Ag colloid in the interface glass layer and increase the interface glass phase conductivity, and SiO2 can weaken the erosion ability of the glass to keep relatively high dopant concentration in the contacted Si surface. The addition of ZnO into the glass may aggravate the erosion to Si and decrease the glass phase conductivity. It is inferred that increasing Bi2O3 and SiO2 or reducing ZnO can improve the glass passivation performance at the contact interface. Through the application in Ag paste metallization, the important effects of the glass compositions on the electrical properties of solar cells are shown that Bi2O3 and SiO2 in the glasses are helpful to increase the open-circuit voltage and short-circuit current, while ZnO is very useful for raising fill factor.

Effect of Binders on the Crushing Strength of Ferro-Coke

Ferro-coke, as a new burden of blast furnace (BF), can not only greatly reduce the energy consumption and CO2 emission, but also promote the resource utilization by using the low-quality iron ore and low-grade coal. However, the strength of ferro-coke decreased with the increasing amount of iron ore powder. In order to maintain the strength of ferro-coke while increasing the amount of iron ore powder, it is necessary to add binder during the coking process to enhance the strength of ferro-coke. In this paper, phenolic resin, silicon metal powder, corn starch, and coal tar pitch were used as binder for the fabrication of ferro-coke. I-type drum machine (I 600), scanning electron microscope (SEM), and X-ray diffraction (XRD) were applied to test the crushing strength, morphology, and microcrystalline structure of the ferro-coke. The results showed that the increasing amount of iron ore powder resulted in lower crushing strength, higher porosity, and the worse macroscopic morphology of ferro-coke. When the amount of iron ore powder reached 40%, obvious cracks appeared on the surface of ferro-coke. When the amount of iron ore was 30%, the crushing strength of ferro-coke dropped to 18.15%. Among the four binders, coal tar pitch could significantly enhance the cold crushing strength of ferro-coke through decreasing the porosity of ferro-coke and improving the bonding effect between carbon matrix particles. In the case of the 10% coal tar pitch addition, the cold crushing strength of ferro-coke was increased from 18.15% to 76.41%; meanwhile, its hot compression strength during gasification improved by 100N.

Mechanical Manipulation of Silicon-based Schottky Diodes via Flexoelectricity

Silicon-based Schottky barrier diodes (SBDs), as a two-terminal circuit element, are widely used in modern industries due to its low cost and better compatibility with the complementary metal oxide semiconductor (CMOS) technology. Flexoelectricity resulting from strain gradient is a distinctive electromechanical coupling phenomenon compared to piezoelectricity resulting from strain. Flexoelectricity can exist in any dielectric due to the non-uniform strain breaking symmetry of materials. In this paper, we utilize the induced flexoelectric polarization to tune the behavior of a SBD made of metal and p-type Silicon. Making use of conductive atomic force microscopy (C-AFM), we measured current-voltage of the fabricated Si-based SBD under different tip forces. In order to conduct a quantitative study on the tuning effect of flexoelectricity on the performance of the fabricated Si-based SBD, we introduce an effective barrier height and provide a modified current equation according to the classical thermionic emission theory. The results show that flexoelectricity plays a significant role in dictating the Schottky barrier height, maximum rectified current (density), reverse saturation current (density), rectification ratio, and open voltage of the fabricated SBD. In addition, based on the Hertzian contact model and the measured data, the nonzero flexoelectric coefficients of the used p-type silicon are obtained.

Эмульсии Пикеринга, стабилизированные некоторыми неорганическими частицами

The paper presents studies of various solid stabilizers of emulsions based on inorganic materials. Inorganic colloidal particles have an advantage for obtaining of stable emulsions due to their safety for use in food, cosmetics, pharmaceutical industry and medicine. Pickering emulsions have a higher biodegradability compared to classical emulsions stabilized with surfactants. An overview of inorganic substances such as silicon dioxide, clay materials, metal and metal oxide nanoparticles, calcium compounds and carbon particles used for stabilizing of Pickering emulsions is considered. A variety of solid inorganic particles as well as modification of their surfaces by surfactants allows to obtain the stable Pickering emulsions of different types for a wide range of applications. It should be noted that despite a large number of studies, this class of disperse systems is still not studied fully; various methods of their preparation and influence of solid particle size on stability and size of emulsions droplets are shown.

Numerical Simulation Analysis of Ag Crystallite Effects on Interface of Front Metal and Silicon in the PERC Solar Cell

In the fabrication of crystalline silicon solar cells, the contact properties between the front metal electrode and silicon are one of the most important parameters for achieving high-efficiency, as it is an integral element in the formation of solar cell electrodes. This entails an increase in the surface recombination velocity and a drop in the open-circuit voltage of the solar cell; hence, controlling the recombination velocity at the metal-silicon interface becomes a critical factor in the process. In this study, the distribution of Ag crystallites formed on the silicon-metal interface, the surface recombination velocity in the silicon-metal interface and the resulting changes in the performance of the Passivated Emitter and Rear Contact (PERC) solar cells were analyzed by controlling the firing temperature. The Ag crystallite distribution gradually increased corresponding to a firing temperature increase from 850 ∘C to 950 ∘C. The surface recombination velocity at the silicon-metal interface increased from 353 to 599 cm/s and the open-circuit voltage of the PERC solar cell decreased from 659.7 to 647 mV. Technology Computer-Aided Design (TCAD) simulation was used for detailed analysis on the effect of the surface recombination velocity at the silicon-metal interface on the PERC solar cell performance. Simulations showed that the increase in the distribution of Ag crystallites and surface recombination velocity at the silicon-metal interface played an important role in the decrease of open-circuit voltage of the PERC solar cell at temperatures of 850–900 ∘C, whereas the damage caused by the emitter over fire was determined as the main cause of the voltage drop at 950 ∘C. These results are expected to serve as a steppingstone for further research on improvement in the silicon-metal interface properties of silicon-based solar cells and investigation on high-efficiency solar cells.

Polymers in Lithium‐Ion and Lithium Metal Batteries

AbstractLithium‐ion batteries play a significant role in modern electronics and electric vehicles. However, current Li‐ion battery chemistries are unable to satisfy the increasingly heightened expectations regarding energy demand and reliability. To boost the overall energy density while ensuring the safety of Li batteries, researchers have focused on alternative battery materials, such as silicon, sulfur, and Li metal. These represent promising avenues, although numerous obstacles (e.g., Si cracking, polysulfide shuttling, Li dendrites, etc.) must be tackled before batteries based on these materials can enter mass production and penetrate the mainstream market. Polymers are a class of materials that are widely used in current battery systems; however, many novel polymer chemistries may offer better performance and reliability than the current ones, and even overcome the issues of the above‐mentioned new battery materials. In this review, selected polymeric materials for solving these issues are categorized into four parts: polymer electrolytes, polymer artificial solid‐electrolyte interphases, binders, and separators. Both the current progress and the characterization methods are included. Potential future directions of energy materials research are pointed out as well.

Principles and impacts of dynamic threshold voltage in a p-GaN gate high-electron-mobility transistor

GaN power transistors are attracting increasing attention for next-generation power switching applications. However, GaN power transistors should not be regarded as a direct replacement for silicon power metal–oxide–semiconductor field-effect transistors, since the unique properties of GaN power transistors require special treatment. In this work we review a unique and critical property of GaN power transistors, the dynamic threshold voltage (V th). GaN power transistors feature a p-GaN gate structure, while the gate metal contacts the p-GaN layer through a Schottky junction. This unique p-GaN gate structure is distinctively different from the silicon metal–oxide–semiconductor gate structure in that the p-GaN layer is actually a floating region without direct electrical contact to the external electrodes of the device. The floating p-GaN layer enables a charge storage process during the switching operation of a p-GaN gate high-electron-mobility transistor. Through carefully designed experiments, the strong correlation between charge storage and the dynamic V th shift has been revealed; this also serves as an approach to accurately predict the dynamic V th during switching operation. The influence of the dynamic V th on power switching applications is discussed. For example, with a positive dynamic V th shift, the reverse conduction voltage of a GaN power transistor is significantly increased, adding to the power loss. This positive V th shift also demands a sufficiently high gate drive voltage to ensure that the GaN power transistor can be fully turned on, which reduces the safety margin for the gate reliability of the device. To design a GaN based power switching circuit, accurate simulation of the device/circuit characteristics is necessary. Circuit simulations that do not consider the dynamic V th lead to a large deviation from the measurement circuit characteristics. We demonstrate that by incorporating the dynamic V th into the circuit model this deviation can be effectively eliminated.

Influence of silicon, boron and rare-earth metals on corrosion resistance of austenitic chromium-nickel steel

The effect of silicon (in range 0.14 – 0.78 wt. %), boron, and rare-earth metals (REM) on the corrosion resistance of low-carbon austenitic chromium-nickel steel of 03Kh18N11 (AISI 304L) grade was studied. It is shown that all steels in quenched state when tested in boiling 56 and 65 % HNO3 solutions have comparable corrosion rates, which do not exceed the critical norm (0.5 mm/year) in accordance with GOST 6032 – 2017 (State Standard). Testing samples in boiling 27 % HNO3 + 4 g/l Cr+6 solution are susceptible to intergranular corrosion (IGC). The corrosion rate and the penetration depth of IGC increase with increasing silicon concentration from 0.14 to 0.78 wt. %. Study of the effect of nitric acid concentration and test temperature has shown that steel with 0.78 wt. % Si has significant corrosion losses exceeding the critical ones when testing in 56 and 65 % HNO3 solutions with temperature of 120 and 130 °С. But steel with high silicon content (0.78 wt. %) and low carbon concentration (0.020 – 0.022 %) after quenching in a range of 1080 – 1150 °C and tempering at 650 °C does not exceed the critical norm on average corrosion rate. Only 0.01 wt. % increase in carbon concentration leads to a significant (more than 30 times) increase in corrosion rate of sensitized steel. It is shown that microalloying with REM does not impair corrosion resistance of sensitized steel. In contrast to REM, alloying chromium-nickel steel with even a small addition of boron (0.0015 %) reduces steel corrosion resistance by an order of magnitude. Corrosion rate inverse dependence on quenching temperature is observed when, with increasing temperature, corrosion rate of 02Kh18N11GS0.38R steel increases. The effect of silicon (in range 0.14 – 0.78 wt. %), boron, and rare-earth metals (REM) on the corrosion resistance of low-carbon austenitic chromium-nickel steel of 03Kh18N11 (AISI 304L) grade was studied. It is shown that all steels in quenched state when tested in boiling 56 and 65 % HNO3 solutions have comparable corrosion rates, which do not exceed the critical norm (0.5 mm/year) in accordance with GOST 6032 – 2017 (State Standard). Testing samples in boiling 27 % HNO3 + 4 g/l Cr+6 solution are susceptible to intergranular corrosion (IGC). The corrosion rate and the penetration depth of IGC increase with increasing silicon concentration from 0.14 to 0.78 wt. %. Study of the effect of nitric acid concentration and test temperature has shown that steel with 0.78 wt. % Si has significant corrosion losses exceeding the critical ones when testing in 56 and 65 % HNO3 solu tions with temperature of 120 and 130 °С. But steel with high silicon content (0.78 wt. %) and low carbon concentration (0.020 – 0.022 %) after quenching in a range of 1080 – 1150 °C and tempering at 650 °C does not exceed the critical norm on average corrosion rate. Only 0.01 wt. % increase in carbon concentration leads to a significant (more than 30 times) increase in corrosion rate of sensitized steel. It is shown that microalloying with REM does not impair corrosion resistance of sensitized steel. In contrast to REM, alloying chromium-nickel steel with even a small addition of boron (0.0015 %) reduces steel corrosion resistance by an order of magnitude. Corrosion rate inverse dependence on quenching temperature is observed when, with increasing temperature, corrosion rate of 02Kh18N11GS0.38R steel increases.

Studies on Energy Cells Based on Si-, Si-Ge- and Ge-Air Systems

Silicon metal may be used as a fuel in Si-Air fuel cells. The most important characteristics of theseenergy cells is its thermodynamic reversibility. The Silicon-air energy cell is highly promising for electric vehicles due to its high theoretical energy density (8470 Wh kg-1) and its discharge products are non-toxic. For the first time, pure silicon and germanium powders are used as anode material. Nickel wire mesh embedded with charcoal and manganese dioxide powder as cathode and concentrated potassium hydroxide is used as electrolyte. Voltage-time curves have been presented in this study for pure silicon and germanium powder, and 5% and 10% germanium with silicon powder.

SIMULATION OF THE DIRECT CARBOTHERMAL REDUCTION OF SiO2 FOR Si METAL USING MATLAB® AND ASPEN-HYSYS®

Silicon metal is one of the most important metals produced from silica by carbothermic reduction in the electric arc furnace which works at high temperatures between 1000 to 3000 oC. The objective of this work is to simulate the direct carbothermal reduction of SiO2 for Si metal by using a thermodynamic calculation of Gibb’s free energy minimization with MATLAB® and Aspen HYSYS®. The comparison of simulation using MATLAB® with reference [10] revealed close results. By increasing the mole ratio up to 10 increases the Si formation and increases the ratio more than 10 mole ratio had very bad results,and not economically viable. Here we did comparison between simulation results using MATLAB® with real assumption and ASPEN HYSYS®.

Challenge with a Personal Cascade Impactor Sampler in a Silicon Metal Smelter

ABSTRACT Cascade impactors are useful tools in the measurement of particle size mass distribution of workplace aerosols. The application of cascade impactors, however, is sometimes challenging. Personal aerosol samples were collected by Sioutas cascade impactors and respirable cyclones in parallel in a silicon (Si) metal smelter to investigate the different particulate matter (PM) fractions. In a second campaign, nine new air samples were collected with the Sioutas personal cascade impactors using stationary sampling. It was found that wall deposition was substantial in the upper stages of the Sioutas cascade impactors, which meant that quite often more PM was deposited on the inner walls of the impactor than on the filter substrates. At the same time, wall deposition did most probably not affect the collection of the finest particles (< 0.25 µm). Besides wall deposition of the particles, the effect of high PM concentration on the impactor performance, particle bouncing and blow off, high particle mass loading and impact fragmentation of the particle agglomerates were considered for explaining the malfunctioning of the Sioutas impactors in the Si metal smelter. Furthermore, concentrations of the finest PM fraction (< 0.25 µm) and respirable fraction both collected by personal sampling are reported and discussed in the paper.

Third time's the charm: intricate non-centrosymmetric polymorphism in LnSiP3 (Ln = La and Ce) induced by distortions of phosphorus square layers.

Complex polymorphic relationships in the LnSiP3 (Ln = La and Ce) family of compounds are reported. An innovative synthetic method was developed to overcome differences in the reactivities of the rare-earth metal and refractory silicon with phosphorus. Reactions of atomically mixed Ln + Si with P allowed for selective control over the reaction outcomes resulting in targeted isolation of three new polymorphs of LaSiP3 and two polymorphs of CeSiP3. In situ X-ray diffraction studies revealed that the developed method bypasses formation of the thermodynamic dead-end, the binary SiP. Careful re-determination of the crystal structure ruled out the previously reported ordered centrosymmetric structure of CeSiP3 and showed that the main LnSiP3 polymorphs crystallize in the non-centrosymmetric Pna21 and Aea2 space groups featuring distinct distortions of the regular P square net to yield either cis-trans 1D phosphorus chains (Pna21) or disordered-2D phosphorus layers (Aea2). The disordered 2D nature of the P layers in the Aea2 LaSiP3 polymorph was confirmed by Raman spectroscopy. A unique centrosymmetric P21/c polymorph was observed for LaSiP3 and has a completely different crystal structure lacking P layers. Consecutive polymorphic transformations at increasing temperatures for LaSiP3(Pna21 → P21/c → Aea2) were derived from optimized synthetic profiles and confirmed by a combination of phonon computations and experimental in situ and ex situ annealings. Crystal structures of the LaSiP3 polymorphs were verified via advanced solid state NMR analysis using 31P MAS and 31P{139La} double resonance techniques. A combination of phonon and electronic structure calculations, NMR T1 relaxation times, UV/Vis/NIR spectroscopy, and resistivity measurements revealed that all the reported polymorphs are semiconductors with resistivities and thermal conductivities strongly dependent on the degree of distortion of P square layers in the crystal structure. Reported here, non-centrosymmetric LnSiP3 polymorphs with tunable resistivity and thermal conductivity provide a platform for the development of novel functional materials with a wide range of applications.

Different types of adsorbents for selenium (Se) removal from water: A review

Development of adsorption materials based on metal oxides, silicon dioxide, carbon, biosorbents and adsorbents, obtained from natural waste, can be used to remove selenium from water. Research on some of these materials is at the laboratory level, while the others were tested in the pilot plants, and a few have found a commercial application. The high adsorption capacities show a possibility of their application for selenium removal from water. This paper presents a literature review of different types of adsorbents for the removal of selenium (Se) from water.

Photothermal treatment of oropharyngeal cancer with carbon-defective silicon carbide.

Oral squamous carcinoma (OSCC) is a clinical common tumor with high recurrence rate and low 5 year survival rate. In this work, photothermal antitumor treatment has been performed to treat OSCC by taking anti-wound infection into consideration. By introducing C defects, we have successfully converted the semi-conductive SiC into metallic carbon-defective silicon carbide (SiC1-x), and endowed it with the near infrared absorption property for photothermal therapy (PTT). The results revealed that SiC1-x mediated PTT treatment could remove solid OSCC tumor in a biosafe way, showing low hematotoxicity, cytotoxicity and tissue toxicity. Moreover, the low invasion of PTT treatment could not only prevent the invasion of bacteria, but also realize an antibacterial effect on the wound, both of which are important for oral surgery. SiC1-x could be excreted from the body post treatment, which thus reduces the long-term potential toxicity. On the whole, this study provided a promising way to treat OSCC in an effective and safe way.

Doping-Less SiC p-i-n Diode: Design and Investigation

We introduce a novel high-voltage SiC p-i-n diode considering a charge plasma approach. This technique facilitates the formation of the anode and the cathode regions within the silicon carbide without requiring any impurity doping by taking advantage of the work-function difference between silicon carbide and metal electrodes. Utilizing the 2-D TCAD simulation, we represent the performance of the proposed doping-less silicon carbide p-i-n diode is analogous to the silicon carbide Schottky diode in terms of forward and reverse characteristics as well as temperature dependency. As opposed to the conventional (doped) silicon carbide p-i-n diode, the doping-less silicon carbide p-i-n diode holds a lower ON-state voltage drop and higher reverse saturation current. Although the doping-less silicon carbide p-i-n diode has the merits of the silicon carbide Schottky diode, but it has leverage over the corresponding counterparts by eliminating the doping and the high thermal budget fabrication processes.

ВЛИЯНИЕ НЕОКСИДНЫХ ДОБАВОК НА СВОЙСТВА СТЕКЛОКЕРАМИЧЕСКИХ ПОКРЫТИЙ ДЛЯ ДЕТАЛЕЙ ИЗ ЖАРОПРОЧНЫХ СПЛАВОВ (обзор)

A review of the scientific and technical literature is presented, which provides examples of improving glass-based coatings by introducing non-oxide modifying additives. The main groups of chemical compounds that are used to improve the properties of glass-ceramic coatings are considered. Such substances include compounds based on boron, silicon and rare earth metals. It is concluded that these additives have a positive effect on the following properties of coatings: heat resistance, heat resistance, mechanical strength, coating formation temperature, temperature coefficient of linear expansion and adhesion strength to the protected material.

Study on the separation of silicon from refining slag of industrial silicon

During the process of production and refining of industrial silicon, the discharged slag usually contains more than 15 mass% of metallic silicon. However, the separation of silicon from slag is very difficult due to the close density of silicon and slag as well as the high viscosity of slag, which results in the waste of resources. In the present work, the effect of Na2O addition on the separation of silicon from slag is investigated in detail. It is found that the optimum separation condition of slag and silicon is 1723 K reacting for 60 min by adding 10 mass% Na2O to the slag. Viscosity and density are two important factors affecting the separation effect of silicon from slag. The addition of Na2O reduces the viscosity of slag and promotes the separation of silicon from slag. Even if the addition of Na2O will decrease the density of slag which is detrimental to the separation of silicon, the density variation is not the determining factor affecting the separation relative to viscosity. The separation and extraction of metallic silicon from silicon slag is of great significance for improving utilization of resources and reducing environmental pollution.