RF performances of inductors integrated on localized p+-type porous silicon regions

To study the influence of localized porous silicon regions on radiofrequency performances of passive devices, inductors were integrated on localized porous silicon regions, full porous silicon sheet, bulk silicon and glass substrates. In this work, a novel strong, resistant fluoropolymer mask is introduced to localize the porous silicon on the silicon wafer. Then, the quality factors and resonant frequencies obtained with the different substrates are presented. A first comparison is done between the performances of inductors integrated on same-thickness localized and full porous silicon sheet layers. The effect of the silicon regions in the decrease of performances of localized porous silicon is discussed. Then, the study shows that the localized porous silicon substrate significantly reduces losses in comparison with high-resistivity silicon or highly doped silicon bulks. These results are promising for the integration of both passive and active devices on the same silicon/porous silicon hybrid substrate.     

碳化硅材料中游离硅及游离碳对性能的影响

研究了全碳粉反应渗硅碳化硅（PCRBSC）材料的结构与力学性能的关系。分析了渗硅碳化硅材料中游离硅（fsi),游离碳（fc)含量对抗折强度的影响。结果表明：参硅碳化硅材料中随游离硅（fsi)含量的增加,其抗折强度下降,并且二者呈直线关系,符合线性复合规划,另一方面,游离碳（fc)含量较高的渗硅碳化硅材料,尽管游离硅（fsi)含量低,但其抗折强度低于等量或较多游离硅（fsi)含量的渗硅碳化硅材料的抗折强度。     

磷矿伴生硅资源制备单质硅的探讨

综述了国内外以四氟化硅、氟硅酸钠（钾）、无定SiO2为硅源制备单质硅的主要方法,并对以无定SiO2为硅源制备单质硅的工艺条件进行了研究与探索。     

多晶硅生产中硅芯氧化问题探究

改良西门子法生产多晶硅中硅芯是多晶硅生长的载体,硅芯氧化会降低多晶硅产品品质,硅芯氧化的产品对下游铸锭、直拉均有不同程度的影响。目前硅芯氧化是影响多晶硅产品质量的一大问题。分析了硅芯氧化机理,针对相关因素开展了试验,提出了降低硅芯氧化率的措施。     

Relaxation of residual microstress in reaction bonded silicon carbide

High temperature annealing reduces the residual microstress in the silicon phase and silicon carbide phase in monolithic reaction bonded silicon carbide and in the matrix of melt-infitrated composites of silicon carbide reinforced with silicon carbide fibers. Stress relaxation is related to creep of the silicon carbide with power-law creep exponents similar to tensile creep in reaction bonded silicon carbide.     

Verfahren zur Herstellung von Solarsilicium

Production of solar silicon. Economic exploitation of solar energy using solar cells made of crystalline silicon is dependent upon a considerable drop in the cost of the silicon raw material which is nowadays produced by standard methods of the semiconductor industry. New procedures for producing less expensive solar silicon can be divided into four groups characterized by different physico-chemical purification techniques: (1) reduction of volatile Si-H-Cl compounds; (2) purification of technical grade silicon (98–99%); (3) reduction of hexafluorosilicates; (4) reduction of silicon dioxide. Among the ten solar silicon processes under discussion, the purification of technical grade silicon and the carbothermal reduction of silicon dioxide have the greatest scope for cost reduction; however, it remains to be established whether the necessary purity can be achieved on an industrial scale.     

From Metallurgical-Grade to Solar-Grade Silicon: An Overview

The non-renewable nature of fossil fuels as an energy source means its future availability is a cause for concern. The world’s energy demand is ever increasing and there is a growing interest in finding alternative renewable, environmentally benign and cheap energy sources like solar energy. This has resulted in the shortage of silicon feedstock for the photovoltaic industry. This is mainly due to the non-availability of a dedicated solar silicon production and the growing demand for silicon feedstock. There has been tremendous research in a quest to develop methods for the production of solar-grade silicon in a cheap and environmentally friendly way. The metallurgical and chemical routes for the production of solar-grade silicon from metallurgical-grade silicon have evolved. The chemical methods are the most researched ones and they are mostly preferred than the metallurgical ones since the former are capable of producing silicon of higher purity. This review discusses some of the available methods so far for the production of solar-grade silicon using metallurgical-grade silicon as a starting material.     

磷肥副产硅胶综合利用新进展

磷肥副产硅胶产量可观,其主要成分是二氧化硅,且含量较高,是加工硅系列产品很好的原料。磷肥副产硅胶理想的利用方法在于能将所含硅元素转化为经济价值较高的硅产品。概述了国内外磷肥副产硅胶综合利用的最新进展,并根据我国磷肥工业发展情况,提出对磷肥副产硅资源综合利用的建议。     

Modelling silicon carbide formation during heating at constant rate

We build a model, at a mesoscopic, nanometric scale, describing the formation of silicon carbide during heating at constant rate followed by holding at a temperature slightly smaller than the eutectic temperature of carbon and silicon. The number of contacts between silicon grains and graphite plates in the initial powder mixture is shown to influence the speed of the reaction during the step associated with the melting of silicon. After dissolution of carbon in liquid silicon, precipitation of silicon carbide is assumed to obey a heterogeneous nucleation mechanism. In agreement with experiments, the simulation results reproduce smaller reaction speeds for larger silicon grains.     

硅溶胶—苯丙乳液复合路标涂料的研制

采用正硅酸乙酯(TEOS)为主要原料,以聚合溶胶法制备硅溶胶,制得的硅溶胶与苯丙乳液冷拼复配得到复合基料,再以该基料制得硅溶胶—苯丙复合路标涂料。通过正交试验分别确定了制备硅溶胶、硅溶胶—苯丙复合乳液和硅溶胶—苯丙复合路标涂料的最优方案。     

硅肥的研究现状及展望

介绍硅肥的性质,并从硅肥的生产工艺、施用功效及施用技术三个方面对硅肥的研究现状作了综述,最后对硅肥的前景做了展望。     

磷肥副产硅胶生产碳化硅的实验研究

磷肥副产硅胶产量可观,其主要成分是二氧化硅,是加工硅系列产品很好的原料.碳化硅属第三代半导体材料,经济价值高,应用前景好.概述了以二氧化硅为硅源制备碳化硅粉体的主要方法,并介绍利用磷肥副产硅胶碳热还原法生产碳化硅的实验研究.     

Formation of silicon nanostructures with a combination of spacer technology and deep reactive ion etching

ABSTRACT: A new method of fabricating high aspect ratio anostructures in silicon without the use of sub-micron lithographic technique is reported. The proposed method comprises two important steps including the use of CMOS spacer technique to form silicon nitride nanostructure masking followed by deep reactive ion etching (DRIE) of the silicon substrate to form the final silicon nanostructures. Silicon dioxide is used as the sacrificial layer to form the silicon nitride nanostructures. With DRIE a high etch selectivity of 50:1 between silicon and silicon nitride was achieved. The use of the spacer technique is particularly advantageous where self-aligned nanostructures with potentially unlimited lengths are formed without the need of submicron lithographic tools and resist materials. With this method, uniform arrays of 100 nm silicon nanostructures which are at least 4 um tall with aspect ratio higher than 40 were successfully fabricated.     

硅膏温度对有机硅消泡剂性能的影响

有机硅消泡剂是在高温下由二甲基硅油和白炭黑制备成硅膏,以硅膏为主体成分,加入不同的添加剂制得均匀浮白色溶液。硅膏的制备温度影响并决定了消泡剂的性能。     

On the Growth and Microstructure of Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

Carbon nanotubes (CNTs) were deposited on various substrates namely untreated silicon and quartz, Fe-deposited silicon and quartz, HF-treated silicon, silicon nitride-deposited silicon, copper foil, and stainless steel mesh using thermal chemical vapor deposition technique. The optimum parameters for the growth and the microstructure of the synthesized CNTs on these substrates are described. The results show that the growth of CNTs is strongly influenced by the substrate used. Vertically aligned multi-walled CNTs were found on quartz, Fe-deposited silicon and quartz, untreated silicon, and on silicon nitride-deposited silicon substrates. On the other hand, spaghetti-type growth was observed on stainless steel mesh, and no CNT growth was observed on HF-treated silicon and copper. Silicon nitride-deposited silicon substrate proved to be a promising substrate for long vertically aligned CNTs of length 110–130 μm. We present a possible growth mechanism for vertically aligned and spaghetti-type growth of CNTs based on these results.     

钾钙肥中氧化硅的缓释性研究（一）

对钾钙肥中有效氧化硅的缓释性进行了研究。分别以水和质量分数为2％的柠檬酸水溶液为浸取液,测定氧化硅随时间变化的溶出率,并模拟植物吸收养分试验,测定氧化硅的累积溶出率。结果表明：氧化硅在水中的溶出率小于其在柠檬酸溶液中的溶出率;在模拟植物吸收养分的情况下,氧化硅完全符合缓释肥标准;钾钙肥中的氧化硅有很好的缓释性。     

The wetting behaviour and reaction kinetics in diamond–silicon carbide systems

The wetting behaviour of silicon on diamond and the interaction of diamond with molten silicon were investigated. It was found that diamond is well wetted by molten silicon reaching a contact angle of about 20° after melting. The wetting is caused by the rapid formation of a SiC interlayer by nucleation of silicon carbide grains on the surface of the diamond. Investigations of the interaction of silicon with CVD diamond, using SEM, showed that the initial rate of SiC formation is very fast and is significantly reduced after the formation of a 4–6 μm thick dense SiC interlayer. At that stage further growth is likely to be controlled by the diffusion of Si and C through the grain boundaries of the silicon carbide interlayer. The results were compared with the interaction of silicon with glassy carbon.     

Catalytic Activity of Noble Metals for Metal-Assisted Chemical Etching of Silicon

ABSTRACT: Metal-assisted chemical etching of silicon is an electroless method that can produce porous silicon by immersing metal-modified silicon in a hydrofluoric acid solution without electrical bias. We have been studying the metal-assisted hydrofluoric acid etching of silicon using dissolved oxygen as an oxidizing agent. Three major factors control the etching reaction and the porous silicon structure: photoillumination during etching, oxidizing agents, and metal particles. In this study, the influence of noble metal particles, silver, gold, platinum, and rhodium, on this etching is investigated under dark conditions: the absence of photogenerated charges in the silicon. The silicon dissolution is localized under the particles, and nanopores are formed whose diameters resemble the size of the metal nanoparticles. The etching rate of the silicon and the catalytic activity of the metals for the cathodic reduction of oxygen in the hydrofluoric acid solution increase in the order of silver, gold, platinum and rhodium.     

A Model for Silicon Self-Diffusion in Silicon Carbide: Anti-Site Defect Motion

A simple defect interaction model was developed that explains the identical activation energies observed for carbon and silicon diffusion in single-crystal silicon carbide. In accord with experimental measurement of nonstoichiometry, the model requires a substantial concentration of silicon anti-site defects. The diffusion of silicon is limited by the motion of these defects; this is suggested to occur by their interaction with carbon vacancies. The model predicts that boron doping will increase both carbon and silicon diffusion coefficients.     

Making reusable reaction-bonded silicon nitride crucibles for silicon casting from kerf-loss silicon waste

Silicon kerf loss during wafer slicing and the broken quartz crucibles after silicon casting are two major solid wastes from photovoltaic (PV) industry. Especially, the recycle of kerf-loss silicon has become an urgent issue because near 100 000 t of solid wastes are generated every year. One of the most meaningful recycle routes of the kerf-loss silicon is to make silicon nitride crucibles to replace the quartz crucibles. In this study, we demonstrated how this is feasible through acid leaching refining, slip casting, and nitridation. The reaction-bonded silicon nitride (RBSN) crucibles after oxidation were found pure enough for silicon ingot growth. More importantly, they could be reused after ingot growth. With the present examples, the potential of using the kerf-loss silicon for fine ceramics is prominent.