Effects of nanostructurized silicon on proliferation of stem and cancer cell.

Science.gov (United States)

Osminkina, L A; Luckyanova, E N; Gongalsky, M B; Kudryavtsev, A A; Gaydarova, A Kh; Poltavtseva, R A; Kashkarov, P K; Timoshenko, V Yu; Sukhikh, G T

2011-05-01

In vitro experiments showed that stem and cancer cells retained their viability on the surface of porous silicon with 10-100 nm nanostructures, but their proliferation was inhibited. Silicon nanoparticles of 100 nm in size obtained by mechanical grinding of porous silicon films or crystal silicon plates in a concentration below 1 mg/ml in solution did not modify viability and proliferation of mouse fibroblast and human laryngeal cancer cells. Additional ultrasonic exposure of cancer cells in the presence of 1 mg/ml silicon nanoparticles added to nutrient medium led to complete destruction of cells or to the appearance of membrane defects blocking their proliferation and initiating their apoptotic death.

A study on the effect of silicon content on mechanical properties

International Nuclear Information System (INIS)

Kwon, C.T.; Nam, T.W.; Lee, S.I.

1978-01-01

In Al-Si alloy, the variation of mechanical properties with silicon contents was investigated the silicon content being varied from 5% to 25%, and the effects of additives and refining elements were also studied. The results obtained are as follows: 1) Sodium treatment made the primary silicon crystals refined and spheroidized, and made the matrix structure intensified. The effect of P treatment on refining primary silicon crystals was greater then that of Na. 2) Tensile strength showed the maximum value at near the eutectic composition and was improved considerably by addition of Mg and treatment with Na. 3) The variation of matrix hardness with silicon contents was not perceptible and the hardness was improved by addition of Mg and treatment with Na. (author)

Porous silicon based anode material formed using metal reduction

Science.gov (United States)

Anguchamy, Yogesh Kumar; Masarapu, Charan; Deng, Haixia; Han, Yongbong; Venkatachalam, Subramanian; Kumar, Sujeet; Lopez, Herman A.

2015-09-22

A porous silicon based material comprising porous crystalline elemental silicon formed by reducing silicon dioxide with a reducing metal in a heating process followed by acid etching is used to construct negative electrode used in lithium ion batteries. Gradual temperature heating ramp(s) with optional temperature steps can be used to perform the heating process. The porous silicon formed has a high surface area from about 10 m.sup.2/g to about 200 m.sup.2/g and is substantially free of carbon. The negative electrode formed can have a discharge specific capacity of at least 1800 mAh/g at rate of C/3 discharged from 1.5V to 0.005V against lithium with in some embodiments loading levels ranging from about 1.4 mg/cm.sup.2 to about 3.5 mg/cm.sup.2. In some embodiments, the porous silicon can be coated with a carbon coating or blended with carbon nanofibers or other conductive carbon material.

Towards solar grade silicon: Challenges and benefits for low cost photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Pizzini, Sergio [Ned Silicon Spa, Via Th. Edison 6, 60027 Osimo (Ancona) (Italy)

2010-09-15

It is well known that silicon in its various structural configurations (single crystal, multicrystalline, amorphous, micro-nanocrystalline) supplies almost 90% of the substrates used in the photovoltaic industry. It is also known, since years, that the photovoltaic (PV) industry shows a marked growth trend, which demanded and demands a continuous, huge increase of the bulk silicon supply in the order of 30%/yr. In order to fulfill their today- and future needs, many companies worldwide took the decision to start the installation of many thousand tons/year plants, most of them using the Siemens process, some of them using the MG route, to produce the so called solar grade (SG) silicon. The advantages of the Siemens process are well known, as it provides ultrapure silicon, directly usable for growing either single crystalline Czochralski ingots or multicrystalline ingots using the directional solidification (DS) technique. The disadvantages are its high energetic cost (a minimum of 120 kWH/kg) and the possible losses of chlorinated gases in the atmosphere, with possible severe environmental problems. The advantages of the MG route are still potential, as there is no commercially available production of solar silicon as yet, and rely on its reduced energetic costs (a maximum of 25-30 kWh/kg) for a feedstock directly usable for growing multicrystalline ingots using the DS technique. The drawbacks of silicon of MG origin are its larger concentration of metallic impurities, as compared with the Siemens one, the higher B and P content, and the potentially high carbon content. The aim of this paper is to deal with some of the problems encountered so far with the silicon of MG origin with respect to the metallic and non-metallic impurities content, as well as to propose technologically feasible solar grade feedstock specifications. (author)

Siloxanes in silicone products intended for food contact

DEFF Research Database (Denmark)

Cederberg, Tommy Licht; Jensen, Lisbeth Krüger

oligomers which might migrate to the food when the product is being used. DTU has proposed two action limits for low molecular weight siloxanes in food contact materials. For the sum of cyclic siloxanes D3 to D8 the limits are 12 mg/kg food for adults and 2 mg/kg food for children. For the sum of cyclic...... siloxanes D3 to D13 and linear siloxanes L3-L13 the limit is 60 mg/kg food. In 49 samples of silicone products intended for food contact from the Norwegian markets content of siloxanes has been measured. Coated paper for baking constituted 8 of the samples and in none of those samples siloxanes were found......Silicone is used in food contact materials due to its excellent physical and chemical properties. It is thermostable and flexible and is used in bakeware and kitchen utensils. Silicone is also used to coat paper to make it water and fat resistant. There is no specific regulation in EU which covers...

Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts

Science.gov (United States)

Bhatt, R. T.; Palczer, A. R.

1998-01-01

Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

Absorption of silicon from artesian aquifer water and its impact on bone health in postmenopausal women: a 12 week pilot study

Directory of Open Access Journals (Sweden)

Lee Tsz

2010-10-01

Full Text Available Abstract Background Decreased bone mineral density and osteoporosis in postmenopausal women represents a growing source of physical limitations and financial concerns in our aging population. While appropriate medical treatments such as bisphosphonate drugs and hormone replacement therapy exist, they are associated with serious side effects such as osteonecrosis of the jaw or increased cardiovascular risk. In addition to calcium and vitamin D supplementation, previous studies have demonstrated a beneficial effect of dietary silicon on bone health. This study evaluated the absorption of silicon from bottled artesian aquifer water and its effect on markers of bone metabolism. Methods Seventeen postmenopausal women with low bone mass, but without osteopenia or osteoporosis as determined by dual x-ray absorptiometry (DEXA were randomized to drink one liter daily of either purified water of low-silicon content (PW or silicon-rich artesian aquifer water (SW (86 mg/L silica for 12 weeks. Urinary silicon and serum markers of bone metabolism were measured at baseline and after 12 weeks and analyzed with two-sided t-tests with p Results The urinary silicon level increased significantly from 0.016 ± 0.010 mg/mg creatinine at baseline to 0.037 ± 0.014 mg/mg creatinine at week 12 in the SW group (p = 0.003, but there was no change for the PW group (0.010 ± 0.004 mg/mg creatinine at baseline vs. 0.009 ± 0.006 mg/mg creatinine at week 12, p = 0.679. The urinary silicon for the SW group was significantly higher in the silicon-rich water group compared to the purified water group (p Conclusions These findings indicate that bottled water from artesian aquifers is a safe and effective way of providing easily absorbed dietary silicon to the body. Although the silicon did not affect bone turnover markers in the short-term, the mineral's potential as an alternative prevention or treatment to drug therapy for osteoporosis warrants further longer-term investigation

Obtaining of polycrystalline silicon for semiconductor industry

International Nuclear Information System (INIS)

Mukashev, F.; Nauryzbaev, M.; Kolesnikov, B.; Ivanov, Y.

1996-01-01

The purpose of the project is to create pilot equipment and optimize the process of obtaining polycrystalline silicon on semi-industrial level. In the past several decades, the historical experience in the developing countries has shown that one of the most promising ways to improve the economy,of a country is to establish semiconductor industry. First of all, the results can help increase defense, national security and create industrial production. The silane method, which has been traditionally' used for obtaining technical and polycrystalline silicon, is to obtain and then to pyrolyzed mono-and poly silanes. Although the traditional methods of obtaining silicon hydrides have specific advantages, such as utilizing by-products, they also have clear shortcomings, i.e. either low output of the ultimate product ( through hydrolysis of Mg 2 Si) or high contents of by-products in it or high contents of dissolving vapors (through decomposing Mg 2 Si in non-water solutions)

Silicon fertilization and soil water tensions on rice development and yield

Directory of Open Access Journals (Sweden)

Jakeline R. de Oliveira

2016-02-01

Full Text Available ABSTRACT The cultivation of upland rice (Oryza sativa in Brazil occurs mainly in the Cerrado, a region with adverse weather conditions. The use of silicon in its cultivation becomes important, since this nutrient provides higher rigidity, lower transpiration and higher resistance to dry spells in rice plants. The objective of the present study was to evaluate the effect of silicon fertilization and soil water tensions on upland rice development and yield in a Cerrado Oxisol. A 5 x 5 fractionated factorial with five soil water tensions (0, 15, 30, 45 and 60 kPa and five silicon doses (0, 120, 240, 480 and 960 mg dm-3 was used, which were distributed in a randomized block design, with four replicates. Plant height, number of tillers, number of panicles, number of grains per panicle, numbers of full and empty grains and percentage of empty grains were evaluated. Silicon fertilization promotes increased tillering in rice plants at the dose of 960 mg dm-3. The numbers of tillers and panicles decreased with the application of silicon up to the doses of 460 and 490 mg dm-3, respectively. The increase in soil water tensions reduced plant height and the number of full grains, and increased the percentage of empty grains of upland rice.

Semiconductor Grade, Solar Silicon Purification Project. [photovoltaic solar energy conversion

Science.gov (United States)

Ingle, W. M.; Rosler, R. S.; Thompson, S. W.; Chaney, R. E.

1979-01-01

A low cost by-product, SiF4, is reacted with mg silicon to form SiF2 gas which is polymerized. The (SiF2)x polymer is heated forming volatile SixFy homologues which disproportionate on a silicon particle bed forming silicon and SiF4. The silicon analysis procedure relied heavily on mass spectroscopic and emission spectroscopic analysis. These analyses demonstrated that major purification had occured and some samples were indistinguishable from semiconductor grade silicon (except possibly for phosphorus). However, electrical analysis via crystal growth reveal that the product contains compensated phosphorus and boron.

Development of Solar Grade (SoG) Silicon

Energy Technology Data Exchange (ETDEWEB)

Joyce, David B; Schmid, Frederick

2008-01-18

The rapid growth of the photovoltaics (PV) industry is threatened by the ongoing shortage of suitable solar grade (SoG) silicon. Until 2004, the PV industry relied on the off spec polysilicon from the electronics industry for feedstock. The rapid growth of PV meant that the demand for SoG silicon predictably surpassed this supply. The long-term prospects for PV are very bright as costs have come down, and efficiencies and economies of scale make PV generated electricity ever more competitive with grid electricity. However, the scalability of the current process for producing poly silicon again threatens the future. A less costly, higher volume production technique is needed to supply the long-term growth of the PV industry, and to reduce costs of PV even further. This long-term need was the motivation behind this SBIR proposal. Upgrading metallurgical grade (MG) silicon would fulfill the need for a low-cost, large-scale production. Past attempts to upgrade MG silicon have foundered/failed/had trouble reducing the low segregation coefficient elements, B, P, and Al. Most other elements in MG silicon can be purified very efficiently by directional solidification. Thus, in the Phase I program, Crystal Systems proposed a variety of techniques to reduce B, P, and Al in MG silicon to produce a low cost commercial technique for upgrading MG silicon. Of the variety of techniques tried, vacuum refining and some slagging and additions turned out to be the most promising. These were pursued in the Phase II study. By vacuum refining, the P was reduced from 14 to 0.22 ppmw and the Al was reduced from 370 ppmw to 0.065 ppmw. This process was scaled to 40 kg scale charges, and the results were expressed in terms of half-life, or time to reduce the impurity concentration in half. Best half-lives were 2 hours, typical were 4 hours. Scaling factors were developed to allow prediction of these results to larger scale melts. The vacuum refining required the development of new crucibles

Silicon photonics at the University of Surrey

Science.gov (United States)

Reed, G. T.; Mashanovich, G.; Gardes, F. Y.; Gwilliam, R. M.; Wright, N. M.; Thomson, D. J.; Timotijevic, B. D.; Litvinenko, K. L.; Headley, W. R.; Smith, A. J.; Knights, A. P.; Jessop, P. E.; Tarr, N. G.; Deane, J. H. B.

2009-05-01

Silicon Photonics is a field that has seen rapid growth and dramatic changes in the past 5 years. According to the MIT Communications Technology Roadmap [1], which aims to establish a common architecture platform across market sectors with a potential $20B in annual revenue, silicon photonics is among the top ten emerging technologies. This has in part been a consequence of the recent involvement of large semiconductor companies around the world, particularly in the USA. Significant investment in the technology has also followed in Japan, Korea, and in the European Union. Low cost is a key driver, so it is imperative to pursue technologies that are mass-producible. Therefore, Silicon Photonics continues to progress at a rapid rate. This paper will describe some of the work of the Silicon Photonics Group at the University of Surrey in the UK. The work is concerned with the sequential development of a series of components for silicon photonic optical circuits, and some of the components are discussed here. In particular the paper will present work on optical waveguides, optical filters, modulators, and lifetime modification of carriers generated by two photon absorption, to improve the performance of Raman amplifiers in silicon.

Silicon mediated biochemical changes in wheat under salinized and ...

African Journals Online (AJOL)

Silicon (Si) can alleviate salinity damage, a major threat to agriculture that causes instability in wheat production. We report on the effects of silicon (150 mg L-1) on the morphological, physiological and biochemical traits in wheat (Triticum aestivum L.) cultivars (salt sensitive; Auqab-2000 and salt tolerant; SARC-5) differing ...

Combined Effects of Phytoestrogen Genistein and Silicon on Ovariectomy-Induced Bone Loss in Rat.

Science.gov (United States)

Qi, Shanshan; Zheng, Hongxing

2017-06-01

This study was performed to evaluate the effect of concomitant supplementation of genistein and silicon on bone mineral density and bone metabolism-related markers in ovariectomized rat. Three-month-old Sprague Dawley female rats were subjected to bilateral ovariectomy (OVX) or sham surgery, and then the OVX rats were randomly divided into four groups: OVX-GEN, OVX-Si, OVX-GEN-Si, and OVX. Genistein and silicon supplementation was started immediately after OVX and continued for 10 weeks. In the OVX-GEN group, 5 mg genistein per gram body weight was injected subcutaneously. The OVX-Si group was given soluble silicon daily in demineralized water (Si 20 mg/kg body weight/day). The OVX-GEN-Si group was given subcutaneous injections of 5 mg genistein per gram body weight, at the same time, given soluble silicon daily (Si 20 mg/kg body weight/day). The results showed that the genistein supplementation in the OVX rats significantly prevented the loss of uterus weight; however, the silicon supplementation showed no effect on the uterus weight loss. The lumbar spine and femur bone mineral density was significantly decreased after OVX surgery; however, this decrease was inhibited by the genistein and/or silicon, and the BMD of the lumbar spine and femur was the highest in the OVX-GEN-Si-treated group. Histomorphometric analyses showed that the supplementation of genistein and/or silicon restored bone volume and trabecular thickness of femoral trabecular bone in the OVX group. Besides, the treatment with genistein and silicon for 10 weeks increased the serum levels of calcium and phosphorus in the OVX rats; serum calcium and serum phosphorus in the OVX-GEN-Si group were higher than those in the OVX-GEN and OVX-Si group (P silicon decreased serum alkaline phosphatase (ALP) and osteocalcin, which were increased by ovariectomy; serum ALP and osteocalcin in the OVX-GEN-Si group were lower than those in the OVX-GEN and OVX-Si groups (P silicon have synergistic effects on

Release of low molecular weight silicones and platinum from silicone breast implants.

Science.gov (United States)

Lykissa, E D; Kala, S V; Hurley, J B; Lebovitz, R M

1997-12-01

We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was

Effect of the pretreatment of silicone penetrant on the performance of the chromium-free chemfilm coated on AZ91D magnesium alloys

International Nuclear Information System (INIS)

Chang, Shiuan-Ho; Niu, Liyuan; Su, Yichang; Wang, Wenquan; Tong, Xian; Li, Guangyu

2016-01-01

This paper reported a new pretreatment of silicone penetrant for forming the chromium-free chemfilm (chemical conversion coating) on the surface of an AZ91D magnesium (Mg) alloy. Through applying micro current on the pretreatment solution, an uniform mask membrane was created on the surface of a Mg alloy. By using X-ray diffraction (XRD), scanning electron microscope (SEM), and Energy Dispersive Spectrometer (EDS) analyses, the chromium-free chemfilm on a Mg alloy was examined to analyze the performance during initial, middle, and final deposition periods. As a result, the pretreatment of silicone penetrant can effectively prevent the chemfilm from cracking, improve the anticorrosion ability and nucleation rate of the chromium-free chemfilm on a Mg alloy, and make the surface crystallization transform a long strip into short axis shape. - Highlights: • An AZ91D Mg alloy was pretreated by using silicone penetrant. • Surface crystallization of the chemfilm on a silicone-pretreated Mg alloy is smooth. • The pretreatment of silicone penetrant for a Mg alloy enhanced the anticorrosion ability.

Effect of the pretreatment of silicone penetrant on the performance of the chromium-free chemfilm coated on AZ91D magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Chang, Shiuan-Ho, E-mail: 1802186169@qq.com [College of Electronic Information and Mechatronic Engineering, Zhaoqing University, Zhaoqing Road, Duanzhou District, Zhaoqing, Guangdong, 526061 (China); Niu, Liyuan [Department of Material Engineer, Zhejiang Industry & Trade Vocational Colledge, WenZhou, 325000 (China); Su, Yichang [Department of Material Engineer, Zhejiang Industry & Trade Vocational Colledge, WenZhou, 325000 (China); College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun, 130025 (China); Wang, Wenquan [College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun, 130025 (China); Tong, Xian [Department of Material Engineer, Zhejiang Industry & Trade Vocational Colledge, WenZhou, 325000 (China); Li, Guangyu [College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun, 130025 (China)

2016-03-01

This paper reported a new pretreatment of silicone penetrant for forming the chromium-free chemfilm (chemical conversion coating) on the surface of an AZ91D magnesium (Mg) alloy. Through applying micro current on the pretreatment solution, an uniform mask membrane was created on the surface of a Mg alloy. By using X-ray diffraction (XRD), scanning electron microscope (SEM), and Energy Dispersive Spectrometer (EDS) analyses, the chromium-free chemfilm on a Mg alloy was examined to analyze the performance during initial, middle, and final deposition periods. As a result, the pretreatment of silicone penetrant can effectively prevent the chemfilm from cracking, improve the anticorrosion ability and nucleation rate of the chromium-free chemfilm on a Mg alloy, and make the surface crystallization transform a long strip into short axis shape. - Highlights: • An AZ91D Mg alloy was pretreated by using silicone penetrant. • Surface crystallization of the chemfilm on a silicone-pretreated Mg alloy is smooth. • The pretreatment of silicone penetrant for a Mg alloy enhanced the anticorrosion ability.

Production of rare earth-silicon-iron alloys

International Nuclear Information System (INIS)

Mehra, O.K.; Bose, D.K.; Gupta, C.K.

1987-01-01

At Metallurgy Division, BARC, improved procedures for producing rare earth-silicon alloys have been investigated. In these methods, reduction of mixed rare earth oxide by a ferro-silicon and aluminium mixture in combination with CaO-MgO flux/CaO-CaF 2 flux have been tried to prepare an alloy product with a higher rare earth recovery at a higher rare earth content than the present commercial production method. The rare earth recovery using CaO-CaF 2 was 85 per cent while in the case of CaO-MgO flux it was 76 per cent. The corresponding rare earth contents in the alloy correspond to 40 per cent and 55 per cent by weight respectively. (author)

Monolithically interconnected Silicon-Film{trademark} module technology: Annual technical report, 25 November 1997--24 November 1998

Energy Technology Data Exchange (ETDEWEB)

Hall, R.B.; Ford, D.H.; Rand, J.A.; Ingram, A.E.

1999-11-11

AstroPower continued its development of an advanced thin-silicon-based photovoltaic module product. This module combines the performance advantages of thin, light-trapped silicon layers with the capability of integration into a low-cost, monolithically interconnected array. This report summarizes the work carried out over the first year of a three-year, cost-shared contract, which has yielded the following results: Development of a low-cost, insulating, ceramic substrate that provides mechanical support at silicon growth temperatures, is matched to the thermal expansion of silicon, provides the optical properties required for light trapping through random texturing, and can be formed in large areas on a continuous basis. Different deposition techniques have been investigated, and AstroPower has developed deposition processes for the back conductive layer, the p-type silicon layer, and the mechanical/chemical barrier layer. Polycrystalline films of silicon have been grown on ceramics using AstroPower's Silicon-Film{trademark} process. These films are from 50 to 75 {micro}m thick, with columnar grains extending through the thickness of the film. Aspect ratios from 5:1 to 20:1 have been observed in these films.

Distribution of impurity elements in slag-silicon equilibria for oxidative refining of metallurgical silicon for solar cell applications

Energy Technology Data Exchange (ETDEWEB)

Johnston, M.D.; Barati, M. [Department of Materials Science and Engineering, The University of Toronto, 184 College Street, Toronto, Ont. (Canada)

2010-12-15

The possibility of refining metallurgical grade silicon to a high-purity product for solar cell applications by the slagging of impurity elements was investigated. Distribution coefficients were determined for B, Ca, Mg, Fe, K and P between magnesia or alumina saturated Al{sub 2}O{sub 3}-CaO-MgO-SiO{sub 2} and Al{sub 2}O{sub 3}-BaO-SiO{sub 2} slags and silicon at 1500 C. The partitioning of the impurity elements between molten silicon and slag was examined in terms of basicity and oxygen potential of the slag, with particular focus on the behaviour of boron and phosphorus. The experimental results showed that both of these aspects of slag chemistry have a significant influence on the distribution coefficient of B and P. Increasing the oxygen potential by additions of silica was found to increase the distribution coefficients for both B and P. Increasing the basicity of the slag was not always effective in achieving high removal of these elements from silicon as excess amounts of basic oxides lower the activity of silica and consequently the oxygen potential. The extent of this effect is such that increasing basicity can lead to a decrease in distribution coefficient. Increasing lime in the slag increased distribution coefficients for B and P, but this counterbalancing effect was such that distributions were the lowest in barium-containing slags, despite barium oxide being the most basic of the fluxes used in this study. The highest removal efficiencies achieved were of the order of 80% and 90% for B and P, respectively. It was demonstrated that for the removal of B and P from metallurgical-grade silicon to solar-grade levels, a slag mass about 5 times the mass of silicon would be required. (author)

Photoacoustic study of nanocrystalline silicon produced by mechanical grinding

Energy Technology Data Exchange (ETDEWEB)

Poffo, C.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.b [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Souza, S.M.; Triches, D.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Grandi, T.A. [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Biasi, R.S. de [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

2011-04-01

Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 {sup o}C the heat transfer is controlled by crystalline component.

Photoacoustic study of nanocrystalline silicon produced by mechanical grinding

International Nuclear Information System (INIS)

Poffo, C.M.; Lima, J.C. de; Souza, S.M.; Triches, D.M.; Grandi, T.A.; Biasi, R.S. de

2011-01-01

Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 o C the heat transfer is controlled by crystalline component.

Comparison of specific production performances by two crystalline silicon PV systems

Directory of Open Access Journals (Sweden)

Martin Fajman

2013-01-01

Full Text Available A comparison of two independent photovoltaic (PV systems located close to each other on the south of the Czech Moravian Highland was accomplished. Due to differences in installation parameters; reference quantities were used to calculate transformed data sets for specific production performances comparison. Differences in monthly and annually daily production were performed by t-test.According to obtained results, it was concluded that annually mean daily productions per 1 kWp of installed capacity and per 1 m2 of active area of the panels are significantly better by single crystal silicon installation in tracking system than by stable installation of a different technology of single crystal silicon. However, comparing this performance per 1 m2 of occupied land by studied power-plants the stable installation performed higher production rates on daily mean basis in majority of months of the year 2010 as well as by annually mean daily production.

Preparation and characterization of a calcium-phosphate-silicon coating on a Mg-Zn-Ca alloy via two-step micro-arc oxidation.

Science.gov (United States)

Dou, Jinhe; Chen, Yang; Chi, Yiming; Li, Huancai; Gu, Guochao; Chen, Chuanzhong

2017-06-14

Magnesium alloys are the most promising implant materials due to their excellent biodegradability. However, their high degradation rate limits their practical application. In this study, we produced a calcium-phosphate (Ca-P) coating and a calcium-phosphate-silicon (Ca-P-Si) coating via one-step and two-step micro-arc oxidation processes, respectively. The microstructure and chemical composition of the MAO coatings were characterized using SEM, XRD and EDS. The degradation behaviors of the MAO coatings and the substrate were investigated using electrochemical techniques and immersion tests in simulated body fluid (SBF). The results show that the silicate was successfully incorporated into the Ca-P coating in the second MAO step, and this also increased the thickness of the coating. The Ca-P-Si coatings remarkably reduced the corrosion rate of the Mg alloy and Ca-P coating during 18 days of immersion in SBF. In addition, the bone-like apatite layer on the sample surface demonstrated the good biomineralization ability of the Ca-P-Si coating. Potentiodynamic polarization results showed that the MAO coating could clearly enhance the corrosion resistance of the Mg alloy. Moreover, we propose the growth mechanism of the MAO coating in the second step.

Annual reports in inorganic and general syntheses 1974

CERN Document Server

Niedenzu, Kurt

1975-01-01

Annual Reports in Inorganic and General Syntheses-1974 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book discusses the chemistry of simple and complex metal hydrides of main groups I, II, and III, boron, aluminium, gallium, indium, thallium, silicon, germanium, tin, lead, phosphorus, arsenic, antimony, bismuth, chalcogens, halogens, and pseudohalogens. The text also describes the chemistry of scandium, yttrium, lanthanides, actinides, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, ma

Annual reports in inorganic and general syntheses 1972

CERN Document Server

Niedenzu, Kurt

1973-01-01

Annual Reports in Inorganic and General Syntheses-1972 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book discusses alkali and alkaline earth elements, alloys, silver, gold, zinc, cadmium, mercury, boron, aluminum, gallium, indium, thallium, yttrium, scandium, lanthanides, actinides, titanium, zirconium, hafnium, Group V and VI transition elements, manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, osmium, rhodium, and iridium. The text also describes the chemistry of palladium, platinum, silicon, germanium, tin,

Silicon in Imperata cylindrica (L.) P. Beauv: content, distribution, and ultrastructure.

Science.gov (United States)

Rufo, Lourdes; Franco, Alejandro; de la Fuente, Vicenta

2014-07-01

Silicon concentration, distribution, and ultrastructure of silicon deposits in the Poaceae Imperata cylindrica (L.) P. Beauv. have been studied. This grass, known for its medicinal uses and also for Fe hyperaccumulation and biomineralization capacities, showed a concentration of silicon of 13,705 ± 9,607 mg/kg dry weight. Silicon was found as an important constituent of cell walls of the epidermis of the whole plant. Silica deposits were found in silica bodies, endodermis, and different cells with silicon-collapsed lumen as bulliforms, cortical, and sclerenchyma cells. Transmission electron microscope observations of these deposits revealed an amorphous material of an ultrastructure similar to that previously reported in silica bodies of other Poaceae.

Update on the possible nutritional importance of silicon.

Science.gov (United States)

Nielsen, Forrest H

2014-10-01

Convincing evidence that silicon is a bioactive beneficial trace element continues to accumulate. The evidence, which has come from human, animal, and in vitro studies performed by several laboratories, indicate that silicon in nutritional and supra nutritional amounts promotes bone and connective tissue health, may have a modulating effect on the immune or inflammatory response, and has been associated with mental health. A plausible mechanism of action for the beneficial effects of silicon is the binding of hydroxyl groups of polyols such that it influences the formation and/or utilization of glycosaminoglycans, mucopolysaccharides, and collagen in connective tissue and bone. In addition, silicon may affect the absorption, retention or action of other mineral elements (e.g., aluminum, copper, magnesium). Based on findings from both animal and human experiments, an intake of silicon of near 25mg/d would be a reasonable suggestion for an adequate intake that would assure its nutritional benefits. Increased intakes of silicon through consuming unrefined grains, certain vegetables, and beverages and cereals made from grains should be recognized as a reasonable dietary recommendation. Published by Elsevier GmbH.

Thermodynamics of Boron Removal from Silicon Using CaO-MgO-Al2O3-SiO2 Slags

Science.gov (United States)

Jakobsson, Lars Klemet; Tangstad, Merete

2018-04-01

Slag refining is one of few metallurgical methods for removal of boron from silicon. It is important to know the thermodynamic properties of boron in slags to understand the refining process. The relation of the distribution coefficient of boron to the activity of silica, partial pressure of oxygen, and capacity of slags for boron oxide was investigated. The link between these parameters explains why the distribution coefficient of boron does not change much with changing slag composition. In addition, the thermodynamic properties of dilute boron oxide in CaO-MgO-Al2O3-SiO2 slags was determined. The ratio of the activity coefficient of boron oxide and silica was found to be the most important parameter for understanding changes in the distribution coefficient of boron for different slags. Finally, the relation between the activity coefficient of boron oxide and slag structure was investigated. It was found that the structure can explain how the distribution coefficient of boron changes depending on slag composition.

Annual reports in inorganic and general syntheses 1973

CERN Document Server

Niedenzu, Kurt

1974-01-01

Annual Reports in Inorganic and General Syntheses-1973 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book covers the synthetic aspects and structural or mechanistic features of elements, including the main group hydrides, alkali and alkaline earth elements, boron, aluminium, gallium, indium, thallium, silicon, germanium, tin, and lead, nitrogen, phosphorus, arsenic, antimony, bismuth, chalcogens, halogens and pseudohalogens, and noble gases. The text also discusses the synthetic aspects and structural or mechanistic features of

Study of optical and luminescence properties of silicon — semiconducting silicide — silicon multilayer nanostructures

International Nuclear Information System (INIS)

Galkin, N.G.; Galkin, K.N.; Dotsenko, S.A.; Goroshko, D.L.; Shevlyagin, A.V.; Chusovitin, E.A.; Chernev, I.M.

2017-01-01

By method of in situ differential spectroscopy it was established that at the formation of monolayer Fe, Cr, Ca, Mg silicide and Mg stannide islands on the atomically clean silicon surface an appearance of loss peaks characteristic for these materials in the energy range of 1.1-2.6 eV is observed. An optimization of growth processes permit to grow monolithic double nanoheterostructures (DNHS) with embedded Fe, Cr and Ca nanocrystals, and also polycrystalline DNHS with NC of Mg silicide and Mg stannide and Ca disilicide. By methods of optical spectroscopy and Raman spectroscopy it was shown that embedded NC form intensive peaks in the reflectance spectra at energies up to 2.5 eV and Raman peaks. In DNS with β-FeSi2 NC a photoluminescence and electroluminescence at room temperature were firstly observed.

Determination of aluminium, silicon and magnesium content in water samples by nuclear physical methods using XRFA and the MT-25 microtron

International Nuclear Information System (INIS)

Maslov, O.D.; Gustova, M.V.; Belov, A.G.; Drobina, T.P.

2011-01-01

Some of element contents in the samples have been determined by nuclear physical methods (XRFA, GAA and NAA). The possibility of determining Al, Si and Mg content in water samples has been studied. The detection limits of 0.03 mg/1 for Al, 0.3 mg/1 for Si and 0.1 mg/1 for Mg in water samples have been obtained. Monitoring of the aluminium and silicon content in water is important because the high concentration of aluminium or the low content of silicon in drinking water may be risk factors for Alzheimer's disease

Electronic structure of deep levels in silicon. A study of gold, magnesium, and iron centers in silicon

International Nuclear Information System (INIS)

Thilderkvist, A. L.

1994-02-01

The electronic structure of gold, magnesium and iron related deep centers in silicon is investigated. Their deep and shallow levels are studied by means of fourier transform spectroscopy, combined with uniaxial stress and Zeeman spectroscopy. The neutral substitutional gold center in silicon is investigated and the center is paramagnetic, S=1/2, with g||≅2.8 and g≅0, and has a static distortion. Reorientation between different equivalent distortions is observed even at 1.9 K. A gold pair center in silicon is studied and several line series, with a zero-phonon line followed by several phonon replicas, are observed. Uniaxial stress and Zeeman results reveal a trigonal symmetry of the center, which together with the high dissociation energy of 1.7 eV suggests that the center consists of two nearest-neighbor substitutional gold atoms. A divacancy model is employed to explain the electronic properties of the center. The interstitial magnesium double donor in silicon in its two charge states Mg o and Mg + is investigated. Deviations in the binding energies of the excited states from those calculated within the effective-mass theory (EMT) are found and explained by a perturbation in the central-cell region. The quadratic Zeeman effect of shallow donors in silicon is analyzed within the framework of the EMT using a numerical approach. The wave functions are calculated in a discrete radial mesh and the Zeeman Hamiltonian has be evaluated for the lowest excited states for fields up to 6 T. The neutral interstitial iron defect in silicon gives rise to two sets of line spectra. The first set arises when an electron is excited to a shallow donor like state where the electron is decoupled from the Fe + core which has a 4 T 1 ground state term. The second set arises when an excited electron of a 1 symmetry is coupled by exchange interaction to the core, yielding at 5 T 1 final state. Experiments determine the multiplet splitting of the 4 T 1 and 5 T 1 states due to spring

Making MgO/SiO2 Glasses By The Sol-Gel Process

Science.gov (United States)

Bansal, Narottam P.

1989-01-01

Silicon dioxide glasses containing 15 mole percent magnesium oxide prepared by sol-gel process. Not made by conventional melting because ingredients immiscible liquids. Synthesis of MgO/SiO2 glass starts with mixing of magnesium nitrate hexahydrate with silicon tetraethoxide, both in alcohol. Water added, and transparent gel forms. Subsequent processing converts gel into glass. Besides producing glasses of new composition at lower processing temperatures, sol-gel method leads to improved homogeneity and higher purity.

Towards scalable binderless electrodes: carbon coated silicon nanofiber paper via Mg reduction of electrospun SiO2 nanofibers.

Science.gov (United States)

Favors, Zachary; Bay, Hamed Hosseini; Mutlu, Zafer; Ahmed, Kazi; Ionescu, Robert; Ye, Rachel; Ozkan, Mihrimah; Ozkan, Cengiz S

2015-02-06

The need for more energy dense and scalable Li-ion battery electrodes has become increasingly pressing with the ushering in of more powerful portable electronics and electric vehicles (EVs) requiring substantially longer range capabilities. Herein, we report on the first synthesis of nano-silicon paper electrodes synthesized via magnesiothermic reduction of electrospun SiO2 nanofiber paper produced by an in situ acid catalyzed polymerization of tetraethyl orthosilicate (TEOS) in-flight. Free-standing carbon-coated Si nanofiber binderless electrodes produce a capacity of 802 mAh g(-1) after 659 cycles with a Coulombic efficiency of 99.9%, which outperforms conventionally used slurry-prepared graphite anodes by over two times on an active material basis. Silicon nanofiber paper anodes offer a completely binder-free and Cu current collector-free approach to electrode fabrication with a silicon weight percent in excess of 80%. The absence of conductive powder additives, metallic current collectors, and polymer binders in addition to the high weight percent silicon all contribute to significantly increasing capacity at the cell level.

Silicon induced improvement in morpho-physiological traits of maize (zea mays l.) under water deficit

International Nuclear Information System (INIS)

Amin, M.; Ahmad, R.; Basra, S.M.A.; Murtaza, G.

2014-01-01

Current water scarcity is an emerging issue in semi-arid regions like Pakistan and cause of deterioration in productivity of crops to reduce crop yield all over the world. Silicon is known to be better against the deleterious effects of drought on plant growth and development. A pot study was conducted to evaluate the effect of Si nutrition (0, 50, 100 and 150 mg/kg) on the growth of a relatively drought tolerant (P-33H25) and sensitive (FH-810) maize hybrids. Two levels of soil water content were used viz. 100 and 60% of field capacity. Water deficit condition in soil significantly reduced morphological and physiological attributes of maize plants. Silicon application significantly improved the plant height, leaf area per plant, primary root length, dry matter of shoot and roots and plant dry matter, water relation and gas exchange characteristics of both maize cultivars under water deficit condition. Poor growth of drought stressed plants was significantly improved with Si application. The silicon fertilized (100 mg/kg) drought stressed plants of hybrid P-33H25 produced maximum (21.68% more) plant dry matter as compared to plants that were not provided with silicon nutrition. Nonetheless, silicon application (150 mg/kg) resulted in maximum increase (26.03%) in plant dry weight of hybrid FH-810 plants that were grown under limited moisture supply i.e., 60% FC. In conclusion silicon application to drought stressed maize plants was better to improve the growth and dry matter could be attributed to improved osmotic adjustment, photosynthetic rate and lowered transpiration. (author)

Methods To Determine the Silicone Oil Layer Thickness in Sprayed-On Siliconized Syringes.

Science.gov (United States)

Loosli, Viviane; Germershaus, Oliver; Steinberg, Henrik; Dreher, Sascha; Grauschopf, Ulla; Funke, Stefanie

2018-01-01

The silicone lubricant layer in prefilled syringes has been investigated with regards to siliconization process performance, prefilled syringe functionality, and drug product attributes, such as subvisible particle levels, in several studies in the past. However, adequate methods to characterize the silicone oil layer thickness and distribution are limited, and systematic evaluation is missing. In this study, white light interferometry was evaluated to close this gap in method understanding. White light interferometry demonstrated a good accuracy of 93-99% for MgF 2 coated, curved standards covering a thickness range of 115-473 nm. Thickness measurements for sprayed-on siliconized prefilled syringes with different representative silicone oil distribution patterns (homogeneous, pronounced siliconization at flange or needle side, respectively) showed high instrument (0.5%) and analyst precision (4.1%). Different white light interferometry instrument parameters (autofocus, protective shield, syringe barrel dimensions input, type of non-siliconized syringe used as base reference) had no significant impact on the measured average layer thickness. The obtained values from white light interferometry applying a fully developed method (12 radial lines, 50 mm measurement distance, 50 measurements points) were in agreement with orthogonal results from combined white and laser interferometry and 3D-laser scanning microscopy. The investigated syringe batches (lot A and B) exhibited comparable longitudinal silicone oil layer thicknesses ranging from 170-190 nm to 90-100 nm from flange to tip and homogeneously distributed silicone layers over the syringe barrel circumference (110- 135 nm). Empty break-loose (4-4.5 N) and gliding forces (2-2.5 N) were comparably low for both analyzed syringe lots. A silicone oil layer thickness of 100-200 nm was thus sufficient for adequate functionality in this particular study. Filling the syringe with a surrogate solution including short

Aligned three-dimensional prismlike magnesium nanostructures realized onto silicon substrate

International Nuclear Information System (INIS)

Zhang Kaili; Rossi, Carole; Tenailleau, Christophe; Alphonse, Pierre

2008-01-01

A simple approach is proposed to realize three-dimensional (3D) prismlike Mg nanostructures, which has several advantages over previous investigations such as suitable for mass production, reduced impurities, tailored dimensions, and easier integration into microsystem. 3D Mg nanostructures are realized onto silicon substrate using a conventional thermal evaporator, where the incident angle of Mg vapor flux with respect to the substrate surface normal is fixed at 88 deg. The as-prepared 3D Mg nanostructures are characterized by scanning electron microscopy, x-ray diffraction, energy dispersive x-ray analysis, transmission electron microscopy, high-resolution transmission electron microscopy, and surface area measurement

Trends in the use of silicone hydrogel contact lenses for daily wear.

Science.gov (United States)

Efron, Nathan; Morgan, Philip B

2008-10-01

Although the first silicone hydrogel contact lenses introduced onto the world contact lens market in 1999 held approval for both daily wear and extended wear use, the latter modality was promoted much more heavily by the manufacturers. The first silicone hydrogel lenses specifically promoted for daily wear were introduced in 2003. Data that we have gathered from annual contact lens fitting surveys demonstrate an immediate increase in market share whereby this lens type now represents more than one-third of soft lens fits in the United Kingdom. The success of this lens category is attributed to the health and safety benefits of silicone hydrogel materials and the positive impact of lens manufacturers by way of the effective marketing and distribution of these products.

Silicate fertilization of tropical soils: silicon availability and recovery index of sugarcane

Directory of Open Access Journals (Sweden)

Mônica Sartori de Camargo

2013-10-01

Full Text Available Sugarcane is considered a Si-accumulating plant, but in Brazil, where several soil types are used for cultivation, there is little information about silicon (Si fertilization. The objectives of this study were to evaluate the silicon availability, uptake and recovery index of Si from the applied silicate on tropical soils with and without silicate fertilization, in three crops. The experiments in pots (100 L were performed with specific Si rates (0, 185, 370 and 555 kg ha-1 Si, three soils (Quartzipsamment-Q, 6 % clay; Rhodic Hapludox-RH, 22 % clay; and Rhodic Acrudox-RA, 68 % clay, with four replications. The silicon source was Ca-Mg silicate. The same Ca and Mg quantities were applied to all pots, with lime and/or MgCl2, when necessary. Sugarcane was harvested in the plant cane and first- and second-ratoon crops. The silicon rates increased soil Si availability and Si uptake by sugarcane and had a strong residual effect. The contents of soluble Si were reduced by harvesting and increased with silicate application in the following decreasing order: Q>RH>RA. The silicate rates promoted an increase in soluble Si-acetic acid at harvest for all crops and in all soils, except RA. The amounts of Si-CaCl2 were not influenced by silicate in the ratoon crops. The plant Si uptake increased according to the Si rates and was highest in RA at all harvests. The recovery index of applied Si (RI of sugarcane increased over time, and was highest in RA.

Deposition of MgB2 Thin Films on Alumina-Buffered Si Substrates by using Hybrid Physical-Chemical Vapor Deposition Method

International Nuclear Information System (INIS)

Lee, T. G.; Park, S. W.; Seong, W. K.; Huh, J. Y.; Jung, S. G.; Kang, W. N.; Lee, B. K.; An, K. S.

2008-01-01

[ MgB 2 ] thin films were fabricated using hybrid physical-chemical vapor deposition (HPCVD) method on silicon substrates with buffers of alumina grown by using atomic layer deposition method. The growth war in a range of temperatures 500 - 600 degrees C and under the reactor pressures of 25 - 50 degrees C. There are some interfacial reactions in the as-grown films with impurities of mostly Mg 2 Si, MgAl 2 O 4 , and other phases. The T c 's of MgB 2 films were observed to be as high as 39 K, but the transition widths were increased with growth temperatures. The magnetization was measured as a function of temperature down to the temperature of 5 K, but the complete Meissner effect was not observed, which shows that the granular nature of weak links is prevailing. The formation of mostly Mg 2 Si impurity in HPCVD process is discussed, considering the diffusion and reaction of Mg vapor with silicon substrates.

Photoluminescence and electrical properties of silicon oxide and silicon nitride superlattices containing silicon nanocrystals

International Nuclear Information System (INIS)

Shuleiko, D V; Ilin, A S

2016-01-01

Photoluminescence and electrical properties of superlattices with thin (1 to 5 nm) alternating silicon-rich silicon oxide or silicon-rich silicon nitride, and silicon oxide or silicon nitride layers containing silicon nanocrystals prepared by plasma-enhanced chemical vapor deposition with subsequent annealing were investigated. The entirely silicon oxide based superlattices demonstrated photoluminescence peak shift due to quantum confinement effect. Electrical measurements showed the hysteresis effect in the vicinity of zero voltage due to structural features of the superlattices from SiOa 93 /Si 3 N 4 and SiN 0 . 8 /Si 3 N 4 layers. The entirely silicon nitride based samples demonstrated resistive switching effect, comprising an abrupt conductivity change at about 5 to 6 V with current-voltage characteristic hysteresis. The samples also demonstrated efficient photoluminescence with maximum at ∼1.4 eV, due to exiton recombination in silicon nanocrystals. (paper)

Preparing rare earth-silicon-iron-aluminum alloys

International Nuclear Information System (INIS)

Marchant, J.D.; Morrice, E.; Herve, B.P.; Wong, M.M.

1980-01-01

As part of its mission to assure the maximum recovery and use of the Nation's mineral resources, the Bureau of Mines, investigated an improved procedure for producing rare earth-silicon alloys. For example, a charge consisting of 681 grams of mixed rare-earth oxides, 309 grams of ferrosilicon (75 wt-pct Si), and 182 grams of aluminum metal along with a flux consisting of 681 grams of CaO and 45 grams of MgO was reacted at 1500 0 C in an induction furnace. Good slag-metal separation was achieved. The alloy product contained, in weight-percent, 53 RE, 28 Si, 11 Fe, and 4 Al with a rare earth recovery of 80 pct. In current industrial practice rare earth recoveries are usually about 60 pct in alloy products that contain approximately 30 wt-pct each of rare earths and silicon. Metallurgical evaluations showed the alloys prepared in this investigation to be as effective in controlling the detrimental effect of sulfur in steel and cast iron as the commercial rare earth-silicon-iron alloys presently used in the steel industry

SIMULATED 8 MeV NEUTRON RESPONSE FUNCTIONS OF A THIN SILICON NEUTRON SENSOR.

Science.gov (United States)

Takada, Masashi; Matsumoto, Tetsuro; Masuda, Akihiko; Nunomiya, Tomoya; Aoyama, Kei; Nakamura, Takashi

2017-12-22

Neutron response functions of a thin silicon neutron sensor are simulated using PHITS2 and MCNP6 codes for an 8 MeV neutron beam at angles of incidence of 0°, 30° and 60°. The contributions of alpha particles created from the 28Si(n,α)25Mg reaction and the silicon nuclei scattered elastically by neutrons in the silicon sensor have not been well reproduced using the MCNP6 code. The 8 MeV neutron response functions simulated using the PHITS2 code with an accurate event generator mode are in good agreement with experimental results and include the contributions of the alpha particles and silicon nuclei. © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Mg-lattice associations in red coralline algae

Science.gov (United States)

Kamenos, N. A.; Cusack, M.; Huthwelker, T.; Lagarde, P.; Scheibling, R. E.

2009-04-01

Recent investigations have shown red coralline algae to record ambient temperature in their calcite skeletons. Temperature recorded by variation in Mg concentrations within algal growth bands has sub-annual resolution and high accuracy. The conversion of Mg concentration to temperature is based on the assumption of Ca replacement by Mg within the algal calcite skeleton at higher temperatures. While Mg-temperature relationships in coralline algae have been calibrated for some species, the location of Mg within the calcite lattice remains unknown. Critically, if Mg is not a lattice component but associated with organic components this could lead to erroneous temperature records. Before coralline algae are used in large scale climate reconstructions it is therefore important to determine the location of Mg. Synchrotron Mg-X-ray absorbance near edge structure (XANES) indicates that Mg is associated with the calcite lattice in Lithothamnion glaciale (contemporary free-living, contemporary encrusting and sub-fossil free-living) and Phymatolithon calcareum (contemporary free-living) coralline algae. Mg is deposited within the calcite lattice in all seasons ( L. glaciale & P. calcareum) and thallus areas ( P. calcareum). These results suggest L. glaciale and P. calcareum are robust Mg-palaeotemperature proxies. We suggest that similar confirmation be obtained for Mg associations in other species of red coralline algae aiding our understanding of their role in climate reconstruction at large spatial scales.

Hybrid III-V Silicon Lasers

Science.gov (United States)

Bowers, John

2014-03-01

Abstract: A number of important breakthroughs in the past decade have focused attention on Si as a photonic platform. We review here recent progress in this field, focusing on efforts to make lasers, amplifiers, modulators and photodetectors on or in silicon. We also describe optimum quantum well design and distributed feedback cavity design to reduce the threshold and increase the efficiency and power output. The impact active silicon photonic integrated circuits could have on interconnects, telecommunications and on silicon electronics is reviewed. Biography: John Bowers holds the Fred Kavli Chair in Nanotechnology, and is the Director of the Institute for Energy Efficiency and a Professor in the Departments of Electrical and Computer Engineering and Materials at UCSB. He is a cofounder of Aurrion, Aerius Photonics and Calient Networks. Dr. Bowers received his M.S. and Ph.D. degrees from Stanford University and worked for AT&T Bell Laboratories and Honeywell before joining UC Santa Barbara. Dr. Bowers is a member of the National Academy of Engineering and a fellow of the IEEE, OSA and the American Physical Society. He is a recipient of the OSA/IEEE Tyndall Award, the OSA Holonyak Prize, the IEEE LEOS William Streifer Award and the South Coast Business and Technology Entrepreneur of the Year Award. He and coworkers received the EE Times Annual Creativity in Electronics (ACE) Award for Most Promising Technology for the hybrid silicon laser in 2007. Bowers' research is primarily in optoelectronics and photonic integrated circuits. He has published ten book chapters, 600 journal papers, 900 conference papers and has received 54 patents. He has published 180 invited papers and conference papers, and given 16 plenary talks at conferences. As well as Chong Zhang.

Photovoltaic Program Branch annual report, FY 1989

Energy Technology Data Exchange (ETDEWEB)

Summers, K A [ed.

1990-03-01

This report summarizes the progress of the Photovoltaic (PV) Program Branch of the Solar Energy Research Institute (SERI) from October 1, 1988, through September 30, 1989. The branch is responsible for managing the subcontracted portion of SERI's PV Advanced Research and Development Project. In fiscal year (FY) 1989, this included nearly 50 subcontracts, with a total annualized funding of approximately $13.1 million. Approximately two-thirds of the subcontracts were with universities, at a total funding of nearly $4 million. The six technical sections of the report cover the main areas of the subcontracted program: Amorphous Silicon Research, Polycrystalline Thin Films, Crystalline Silicon Materials Research, High-Efficiency Concepts, New Ideas, and University Participation. Technical summaries of each of the subcontracted programs provide a discussion of approaches, major accomplishments in FY 1989, and future research directions. Each report will be cataloged individually.

Polyethylene Nanocomposites for the Next Generation of Ultralow-Transmission-Loss HVDC Cables: Insulation Containing Moisture-Resistant MgO Nanoparticles.

Science.gov (United States)

Pourrahimi, Amir Masoud; Pallon, Love K H; Liu, Dongming; Hoang, Tuan Anh; Gubanski, Stanislaw; Hedenqvist, Mikael S; Olsson, Richard T; Gedde, Ulf W

2016-06-15

The use of MgO nanoparticles in polyethylene for cable insulation has attracted considerable interest, although in humid media the surface regions of the nanoparticles undergo a conversion to a hydroxide phase. A facile method to obtain MgO nanoparticles with a large surface area and remarkable inertness to humidity is presented. The method involves (a) low temperature (400 °C) thermal decomposition of Mg(OH)2, (b) a silicone oxide coating to conceal the nanoparticles and prevent interparticle sintering upon exposure to high temperatures, and (c) heat treatment at 1000 °C. The formation of the hydroxide phase on these silicone oxide-coated MgO nanoparticles after extended exposure to humid air was assessed by thermogravimetry, infrared spectroscopy, and X-ray diffraction. The nanoparticles showed essentially no sign of any hydroxide phase compared to particles prepared by the conventional single-step thermal decomposition of Mg(OH)2. The moisture-resistant MgO nanoparticles showed improved dispersion and interfacial adhesion in the LDPE matrix with smaller nanosized particle clusters compared with conventionally prepared MgO. The addition of 1 wt % moisture-resistant MgO nanoparticles was sufficient to decrease the conductivity of polyethylene 30 times. The reduction in conductivity is discussed in terms of defect concentration on the surface of the moisture-resistant MgO nanoparticles at the polymer/nanoparticle interface.

Effective Chemical Route to 2D Nanostructured Silicon Electrode Material: Phase Transition from Exfoliated Clay Nanosheet to Porous Si Nanoplate

International Nuclear Information System (INIS)

Adpakpang, Kanyaporn; Patil, Sharad B.; Oh, Seung Mi; Kang, Joo-Hee; Lacroix, Marc; Hwang, Seong-Ju

2016-01-01

Graphical abstract: Effective morphological control of porous silicon 2D nanoplate can be achieved by the magnesiothermically-induced phase transition of exfoliated silicate clay nanosheets. The promising lithium storage performance of the obtained silicon materials with huge capacity and excellent rate characteristics underscores the prime importance of porously 2D nanostructured morphology of silicon. - Highlights: • 2D nanostructured silicon electrode materials are successfully synthesized via the magnesiothermically-induced phase transition of exfoliated clay 2D nanosheets. • High discharge capacity and rate capability are achieved from the 2D nanoplates of silicon. • Silicon 2D nanoplates can enhance both Li"+ diffusion and charge-transfer kinetics. • 2D nanostructured silicon is beneficial for the cycling stability by minimizing the volume change during lithiation-delithiation. - Abstract: An efficient and economical route for the synthesis of porous two-dimensional (2D) nanoplates of silicon is developed via the magnesiothermically-induced phase transition of exfoliated clay 2D nanosheets. The magnesiothermic reaction of precursor clay nanosheets prepared by the exfoliation and restacking with Mg"2"+ cations yields porous 2D nanoplates of elemental silicon. The variation in the Mg:SiO_2 ratio has a significant effect on the porosity and connectivity of silicon nanoplates. The porous silicon nanoplates show a high discharge capacity of 2000 mAh g"−"1 after 50 cycles. Of prime importance is that this electrode material still retains a large discharge capacity at higher C-rates, which is unusual for the elemental silicon electrode. This is mainly attributed to the improved diffusion of lithium ions, charge-transfer kinetics, and the preservation of the electrical connection of the porous 2D plate-shaped morphology. This study highlights the usefulness of clay mineral as an economical and scalable precursor of high-performance silicon electrodes with

The Effectiveness of Al-Si Coatings for Preventing Interfacial Reaction in Al - Mg Dissimilar Metal Welding

OpenAIRE

Wang, Yin; Al-Zubaidy, Basem; Prangnell, Philip

2017-01-01

The dissimilar welding of aluminum to magnesium is challenging because of the rapid formation of brittle intermetallic compounds (IMC) at the weld interface. An Al-Si coating interlayer was selected to address this problem, based on thermodynamic calculations that predicted silicon would change the reaction path to avoid formation of the normally observed binary Al-Mg IMC phases (-Al3Mg2 and -Al12Mg17). Long-term static heat treatments confirmed that a Si-rich coating will preferentially pr...

Silicone metalization

Energy Technology Data Exchange (ETDEWEB)

Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

2008-12-09

A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

Formation of porous silicon oxide from substrate-bound silicon rich silicon oxide layers by continuous-wave laser irradiation

Science.gov (United States)

Wang, Nan; Fricke-Begemann, Th.; Peretzki, P.; Ihlemann, J.; Seibt, M.

2018-03-01

Silicon nanocrystals embedded in silicon oxide that show room temperature photoluminescence (PL) have great potential in silicon light emission applications. Nanocrystalline silicon particle formation by laser irradiation has the unique advantage of spatially controlled heating, which is compatible with modern silicon micro-fabrication technology. In this paper, we employ continuous wave laser irradiation to decompose substrate-bound silicon-rich silicon oxide films into crystalline silicon particles and silicon dioxide. The resulting microstructure is studied using transmission electron microscopy techniques with considerable emphasis on the formation and properties of laser damaged regions which typically quench room temperature PL from the nanoparticles. It is shown that such regions consist of an amorphous matrix with a composition similar to silicon dioxide which contains some nanometric silicon particles in addition to pores. A mechanism referred to as "selective silicon ablation" is proposed which consistently explains the experimental observations. Implications for the damage-free laser decomposition of silicon-rich silicon oxides and also for controlled production of porous silicon dioxide films are discussed.

Composites comprising silicon carbide fibers dispersed in magnesia-aluminate matrix and fabrication thereof and of other composites by sinter forging

Science.gov (United States)

Panda, Prakash C.; Seydel, Edgar R.; Raj, Rishi

1989-10-03

A novel ceramic-ceramic composite of a uniform dispersion of silicon carbide fibers in a matrix of MgO.multidot.nAl.sub.2 O.sub.3 wherein n ranges from about 1 to about 4.5, said composite comprising by volume from 1 to 50% silicon carbide fibers and from 99 to 50% MgO.multidot.nAl.sub.2 O.sub.3. The composite is readily fabricated by forming a powder comprising a uniform dispersion of silicon carbide fibers in poorly crystalline phase comprising MgO and Al.sub.2 O.sub.3 in a mole ratio of n and either (a) hot pressing or preferably (b) cold pressing to form a preform and then forging utilizing a temperature in the range of 1100.degree. C. to 1900.degree. C. and a strain rate ranging from about 10.sup.-5 seconds .sup.-1 to about 1 seconds .sup.-1 so that surfaces cracks do not appear to obtain a shear deformation greater than 30%.

CdCl2 passivation of polycrystalline CdMgTe and CdZnTe absorbers for tandem photovoltaic cells

Science.gov (United States)

Swanson, Drew E.; Reich, Carey; Abbas, Ali; Shimpi, Tushar; Liu, Hanxiao; Ponce, Fernando A.; Walls, John M.; Zhang, Yong-Hang; Metzger, Wyatt K.; Sampath, W. S.; Holman, Zachary C.

2018-05-01

As single-junction silicon solar cells approach their theoretical limits, tandems provide the primary path to higher efficiencies. CdTe alloys can be tuned with magnesium (CdMgTe) or zinc (CdZnTe) for ideal tandem pairing with silicon. A II-VI/Si tandem holds the greatest promise for inexpensive, high-efficiency top cells that can be quickly deployed in the market using existing polycrystalline CdTe manufacturing lines combined with mature silicon production lines. Currently, all high efficiency polycrystalline CdTe cells require a chloride-based passivation process to passivate grain boundaries and bulk defects. This research examines the rich chemistry and physics that has historically limited performance when extending Cl treatments to polycrystalline 1.7-eV CdMgTe and CdZnTe absorbers. A combination of transmittance, quantum efficiency, photoluminescence, transmission electron microscopy, and energy-dispersive X-ray spectroscopy clearly reveals that during passivation, Mg segregates and out-diffuses, initially at the grain boundaries but eventually throughout the bulk. CdZnTe exhibits similar Zn segregation behavior; however, the onset and progression is localized to the back of the device. After passivation, CdMgTe and CdZnTe can render a layer that is reduced to predominantly CdTe electro-optical behavior. Contact instabilities caused by inter-diffusion between the layers create additional complications. The results outline critical issues and paths for these materials to be successfully implemented in Si-based tandems and other applications.

Low-energy nuclear physics with high-segmentation silicon arrays

International Nuclear Information System (INIS)

Betts, R.R.; Univ. of Illinois, Chicago, IL

1994-01-01

A brief history is given of silicon detectors leading up to the development of ion-implanted strip detectors. Two examples of their use in low energy nuclear physics are discussed; the search for exotic alpha-chain states in 24 Mg and studies of anomalous positron-electron pairs produced in collisions of very heavy ions

Hot corrosion studies on nickel-based alloys containing silicon

International Nuclear Information System (INIS)

Kerr, T.W.; Simkovich, G.

1976-01-01

Alloys of Ni--Cr, Ni--Si and Ni--Cr--Si were oxidized and ''hot corroded'' in pure oxygen at 1000 0 C. In the oxidation experiments it was found that small amounts of either chromium or silicon in nickel increased the oxidation rates in comparison to pure nickel in accord with Wagner's parabolic oxidation theory. At high concentrations of the alloying elements the oxidation rates decreased due to the formation of oxide phases other than nickel oxide in the scale. Hot corrosion experiments were conducted on both binary and ternary alloys by oxidizing samples coated with 1.0 mg/cm 2 of Na 2 SO 4 in oxygen at 1000 0 C. In general it was found that high chromium and high silicon alloys displayed excellent resistance to the hot corrosion process gaining or losing less than 0.5 mg/cm 2 in 1800 min at temperature. Microprobe and x-ray diffraction studies of the alloy and the scale indicate that amorphous SiO 2 probably formed to aid in retarding both the oxidation and the hot corrosion process

ANSTO. Annual Report 1992-1993

International Nuclear Information System (INIS)

1993-11-01

Significant events and achievements highlighted in the Annual Reports include: the Research Reactor Review, increase of external revenues by 12.5%, sales of Australian radioisotopes amounting to $8.5 M, regulatory approval for production of thallium-201 in National Medical Cyclotron, completion of first contracts with Wismut GmbH in Germany, production of a database of content of atmospheric particulate matter in air over NSW, word-wide licence agreement signed for further commercialization of blood clot radiopharmaceuticals, collaborative agreement signed with SURPAC Int. for development of geochemical speciation software, complete design of rings in HIFAR for silicon doping. ills., tabs

Oxygen defect processes in silicon and silicon germanium

KAUST Repository

Chroneos, A.

2015-06-18

Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

Oxygen defect processes in silicon and silicon germanium

KAUST Repository

Chroneos, A.; Sgourou, E. N.; Londos, C. A.; Schwingenschlö gl, Udo

2015-01-01

Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

The pH dependence of silicon-iron interaction in rats.

Science.gov (United States)

Jia, X; Emerick, R J; Kayongo-Male, H

1997-01-01

A 2 x 2 x 3 factorial experiment was conducted to study the pH dependence of a silicon-iron interaction in vivo. The dietary treatments used in the factorial design were the following (mg/kg of diet): silicon, 0 and 500; iron, 35 and 187; acid-base, ammonium chloride as 0.5% of total diet (acidic), sodium bicarbonate as 1.0% of total diet (basic), or no supplementation of acid or base (control). The supplementation of 500 mg silicon/kg of diet increased plasma-iron concentration in rats fed the acidic or control diets, but not in rats fed the basic diet. A high dietary-iron level suppressed copper absorption and utilization and subsequently imposed a negative effect on its own utilization. An increase in the plasma total-cholesterol concentration caused by high dietary-iron level was likely a consequence of the antagonistic effect of iron on copper absorption and utilization. The use of cupric sulfate pentahydrate as the dietary-copper source in this study resulted in plasma copper concentrations that were approximately twice those obtained in a related study using cupric carbonate. Also, a 42% coefficient of variation (C.V.) for plasma-copper concentrations of rats fed cupric sulfate in this study was greatly reduced from the C.V. = 108% previously associated with the dietary cupric carbonate.

Development and evaluation of die materials for use in the growth of silicon ribbons by the inverted ribbon growth process, task 2. LSSA project

Science.gov (United States)

Duffy, M. T.; Berkman, S.; Moss, H. S.; Cullen, G. W.

1978-01-01

The results of emission spectroscopic analysis indicate that molten silicon can remain in contact with hot-pressed Si3N4 (99.2 percent theoretical density) for prolonged periods without attaining the impurity content level of the nitride. Although MgO was used as binder, Mg was not found present in the silicon sessile drop in quantities much above the level initially present in the silicon source material. Preliminary experiments with EFG-type dies coated with CVD Si3N4 or CVD SiOxNy indicate that capillary rise does not occur readily in these dies. The same was found to be true of hot-pressed and reaction-sintered Si3N4 obtained commercially. However, when dies were formed by depositing CVD layers on shaped silicon slabs, a column of molten silicon was maintained in each CVD die while being heated in contact with a crucible of molten silicon. Preliminary wetting of dies appears necessary for EFG growth. Several ribbon growth experiments were performed from V-shaped dies.

Silicon epitaxy on textured double layer porous silicon by LPCVD

International Nuclear Information System (INIS)

Cai Hong; Shen Honglie; Zhang Lei; Huang Haibin; Lu Linfeng; Tang Zhengxia; Shen Jiancang

2010-01-01

Epitaxial silicon thin film on textured double layer porous silicon (DLPS) was demonstrated. The textured DLPS was formed by electrochemical etching using two different current densities on the silicon wafer that are randomly textured with upright pyramids. Silicon thin films were then grown on the annealed DLPS, using low-pressure chemical vapor deposition (LPCVD). The reflectance of the DLPS and the grown silicon thin films were studied by a spectrophotometer. The crystallinity and topography of the grown silicon thin films were studied by Raman spectroscopy and SEM. The reflectance results show that the reflectance of the silicon wafer decreases from 24.7% to 11.7% after texturing, and after the deposition of silicon thin film the surface reflectance is about 13.8%. SEM images show that the epitaxial silicon film on textured DLPS exhibits random pyramids. The Raman spectrum peaks near 521 cm -1 have a width of 7.8 cm -1 , which reveals the high crystalline quality of the silicon epitaxy.

Optimization of Fluorescent Silicon Nano material Production Using Peroxide/ Acid/ Salt Technique

International Nuclear Information System (INIS)

Abuhassan, L.H.

2009-01-01

Silicon nano material was prepared using the peroxide/ acid/ salt technique in which an aqueous silicon-based salt solution was added to H 2 O 2 / HF etchants. In order to optimize the experimental conditions for silicon nano material production, the amount of nano material produced was studied as a function of the volume of the silicon salt solution used in the synthesis. A set of samples was prepared using: 0, 5, 10, 15, and 20 ml of an aqueous 1 mg/ L metasilicate solution. The area under the corresponding peaks in the infrared (ir) absorption spectra was used as a qualitative indicator to the amount of the nano material present. The results indicated that using 10 ml of the metasilicate solution produced the highest amount of nano material. Furthermore, the results demonstrated that the peroxide/ acid/ salt technique results in the enhancement of the production yield of silicon nano material at a reduced power demand and with a higher material to void ratio. A model in which the silicon salt forms a secondary source of silicon nano material is proposed. The auxiliary nano material is deposited into the porous network causing an increase in the amount of nano material produced and a reduction in the voids present. Thus a reduction in the resistance of the porous layer, and consequently reduction in the power required, are expected. (author)

Nanoparticle enhanced evaporation of liquids: A case study of silicone oil and water

OpenAIRE

Zhang, Wenbin; Shen, Rong; Lu, Kunquan; Ji, Ailing; Cao, Zexian

2012-01-01

Evaporation is a fundamental physical phenomenon, of which many challenging questions remain unanswered. Enhanced evaporation of liquids in some occasions is of enormous practical significance. Here we report the enhanced evaporation of the nearly permanently stable silicone oil by dispersing with nanopariticles including CaTiO3, anatase and rutile TiO2. An evaporation rate as high as 1.33 mg/h·cm2 was measured in silicone oil when dispersed with 100 nm-sized CaTiO3 particles. Dependence of e...

Silicon ribbon growth by a capillary action shaping technique. Annual report (Quarterly technical progress report No. 9)

Energy Technology Data Exchange (ETDEWEB)

Schwuttke, G.H.; Ciszek, T.F.; Kran, A.

1977-10-01

Progress on the technological and economical assessment of ribbon growth of silicon by a capillary action shaping technique is reported. Progress in scale-up of the process from 50 mm to 100 mm ribbon widths is presented, the use of vitreous carbon as a crucible material is analyzed, and preliminary tests of CVD Si/sub 3/N/sub 4/ as a potential die material are reported. Diffusion length measurements by SEM, equipment and procedure for defect display under MOS structure in silicon ribbon for lifetime interpretation, and an assessment of ribbon technology are discussed. (WHK)

Silicon Alleviates Nonalcoholic Steatohepatitis by Reducing Apoptosis in Aged Wistar Rats Fed a High-Saturated Fat, High-Cholesterol Diet.

Science.gov (United States)

Garcimartín, Alba; López-Oliva, M Elvira; Sántos-López, Jorge A; García-Fernández, Rosa A; Macho-González, Adrián; Bastida, Sara; Benedí, Juana; Sánchez-Muniz, Francisco J

2017-06-01

Background: Lipoapoptosis has been identified as a key event in the progression of nonalcoholic fatty liver disease (NAFLD), and hence, antiapoptotic agents have been recommended as a possible effective treatment for nonalcoholic steatohepatitis (NASH). Silicon, included in meat as a functional ingredient, improves lipoprotein profiles and liver antioxidant defenses in aged rats fed a high-saturated fat, high-cholesterol diet (HSHCD). However, to our knowledge, the antiapoptotic effect of this potential functional meat on the liver has never been tested. Objective: This study was designed to evaluate the effect of silicon on NASH development and the potential antiapoptotic properties of silicon in aged rats. Methods: One-year-old male Wistar rats weighing ∼500 g were fed 3 experimental diets containing restructured pork (RP) for 8 wk: 1 ) a high-saturated fat diet, as an NAFLD control, with 16.9% total fat, 0.14 g cholesterol/kg diet, and 46.8 mg SiO 2 /kg (control); 2 ) the HSHCD as a model of NASH, with 16.6% total fat, 16.3 g cholesterol/kg diet, and 46.8 mg SiO 2 /kg [high-cholesterol diet (Chol-C)]; and 3 ) the HSHCD with silicon-supplemented RP with amounts of fat and cholesterol identical to those in the Chol-C diet, but with 750 mg SiO 2 /kg (Chol-Si). Detailed histopathological assessments were performed, and the NAFLD activity score (NAS) was calculated. Liver apoptosis and damage markers were evaluated by Western blotting and immunohistochemical staining. Results: Chol-C rats had a higher mean NAS (7.4) than did control rats (1.9; P silicon substantially affects NASH development in aged male Wistar rats fed an HSHCD by partially blocking apoptosis. These results suggest that silicon-enriched RP could be used as an effective nutritional strategy in preventing NASH. © 2017 American Society for Nutrition.

Production of electronic grade lunar silicon by disproportionation of silicon difluoride

Science.gov (United States)

Agosto, William N.

1993-01-01

Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

Thin films of thermoelectric compound Mg2Sn deposited by co-sputtering assisted by multi-dipolar microwave plasma

International Nuclear Information System (INIS)

Le-Quoc, H.; Lacoste, A.; Hlil, E.K.; Bes, A.; Vinh, T. Tan; Fruchart, D.; Skryabina, N.

2011-01-01

Highlights: → Mg 2 Sn thin films deposited by plasma co-sputtering, on silicon and glass substrates. → Formation of nano-grained polycrystalline films on substrates at room temperature. → Structural properties vary with target biasing and target-substrate distance. → Formation of the hexagonal phase of Mg 2 Sn in certain deposition conditions. → Power factor ∼5.0 x 10 -3 W K -2 m -1 for stoichiometric Mg 2 Sn films doped with ∼1 at.% Ag. - Abstract: Magnesium stannide (Mg 2 Sn) thin films doped with Ag intended for thermoelectric applications are deposited on both silicon and glass substrates at room temperature by plasma assisted co-sputtering. Characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction confirms the formation of fine-grained polycrystalline thin films with thickness of 1-3 μm. Stoichiometry, microstructure and crystal structure of thin films are found to vary with target biasing and the distance from targets to substrate. Measurements of electrical resistivity and Seebeck coefficient at room temperature show the maximum power factor of ∼5.0 x 10 -3 W K -2 m -1 for stoichiometric Mg 2 Sn thin films doped with ∼1 at.% Ag.

Property control of graphene aerogels by in situ growth of silicone polymer

Science.gov (United States)

Zhou, Shuai; Zhou, Xiang; Hao, Gazi; Jiang, Wei; Wang, Tianhe

2018-05-01

Modulation of the density (from 3.5 to 64 mg cm-3), hydrophobicity and oil-uptake capability of graphene aerogels in extensive ranges were achieved by reacting (3-Mercaptopropyl)trimethoxysilane (MPS) with graphene oxide solutions under heating. The reaction allowed a characteristic silicone substructure to be formed on graphene and joint the graphene layers firmly together. With the increase of MPS concentrations (≤ca. 0.2 vol%), the nano silicone polymer grown on graphene functioned as a "linker" and "spacer", leading to a substantial decrease of the aerogel density. Because of the formation of silicone polymer and the characteristic nano-micro substructures on the backbones of graphene aerogels, the graphene aerogels exhibited a high hydrophobicity with the water contact angle consistently exceeding 142 degrees. Functionalized graphene aerogels with a density of 3.5 mg cm-3 were conveniently fabricated that displayed an extraordinary oil absorption capacity, 182 times for lubricating oil and 143 times for n-hexane of its own weight. Furthermore, the aerogels maintained their ultra-high absorption capability even after 20 absorption-distillation cycles, due to structural integrity held by the strong interfacial adhesion between graphene sheets and polymer chains of aerogels. This study offers a promising graphene aerogels and also provides a strategy for fabricating extra low dense functional materials.

Large-Scale PV Module Manufacturing Using Ultra-Thin Polycrystalline Silicon Solar Cells: Final Subcontract Report, 1 April 2002--28 February 2006

Energy Technology Data Exchange (ETDEWEB)

Wohlgemuth, J.; Narayanan, M.

2006-07-01

The major objectives of this program were to continue advances of BP Solar polycrystalline silicon manufacturing technology. The Program included work in the following areas. (1) Efforts in the casting area to increase ingot size, improve ingot material quality, and improve handling of silicon feedstock as it is loaded into the casting stations. (2) Developing wire saws to slice 100-..mu..m-thick silicon wafers on 290-..mu..m-centers. (3) Developing equipment for demounting and subsequent handling of very thin silicon wafers. (4) Developing cell processes using 100-..mu..m-thick silicon wafers that produce encapsulated cells with efficiencies of at least 15.4% at an overall yield exceeding 95%. (5) Expanding existing in-line manufacturing data reporting systems to provide active process control. (6) Establishing a 50-MW (annual nominal capacity) green-field Mega-plant factory model template based on this new thin polycrystalline silicon technology. (7) Facilitating an increase in the silicon feedstock industry's production capacity for lower-cost solar-grade silicon feedstock..

Micromachined silicon seismic accelerometer development

Energy Technology Data Exchange (ETDEWEB)

Barron, C.C.; Fleming, J.G.; Montague, S. [and others

1996-08-01

Batch-fabricated silicon seismic transducers could revolutionize the discipline of seismic monitoring by providing inexpensive, easily deployable sensor arrays. Our ultimate goal is to fabricate seismic sensors with sensitivity and noise performance comparable to short-period seismometers in common use. We expect several phases of development will be required to accomplish that level of performance. Traditional silicon micromachining techniques are not ideally suited to the simultaneous fabrication of a large proof mass and soft suspension, such as one needs to achieve the extreme sensitivities required for seismic measurements. We have therefore developed a novel {open_quotes}mold{close_quotes} micromachining technology that promises to make larger proof masses (in the 1-10 mg range) possible. We have successfully integrated this micromolding capability with our surface-micromachining process, which enables the formation of soft suspension springs. Our calculations indicate that devices made in this new integrated technology will resolve down to at least sub-{mu}G signals, and may even approach the 10{sup -10} G/{radical}Hz acceleration levels found in the low-earth-noise model.

Annual Report: Photovoltaic Subcontract Program FY 1990

Energy Technology Data Exchange (ETDEWEB)

Summers, K. A. [Solar Energy Research Inst., Golden, CO (United States)

1991-03-01

This report summarizes the progress of the Photovoltaic (PV) Subcontract Program of the Solar Energy Research Institute (SERI) from October 1, 1989 through September 30, 1990. The PV Subcontract Program is responsible for managing the subcontracted portion of SERI's PV Advanced Research and Development Project. In fiscal year 1990, this included more than 54 subcontracts with a total annualized funding of approximately $11.9 million. Approximately two-thirds of the subcontracts were with universities at a total funding of nearly $3.3 million. The six technical sections of the report cover the main areas of the subcontract program: the Amorphous Silicon Research Project, Polycrystalline Thin Films, Crystalline Silicon Materials Research, High-Efficiency Concepts, the New Ideas Program, and the University Participation Program. Technical summaries of each of the subcontracted programs provide a discussion of approaches, major accomplishments in FY 1990, and future research directions. Another section introduces the PVMaT project and reports on its progress.

Optimizing silicon application to improve salinity tolerance in wheat

Directory of Open Access Journals (Sweden)

A. Ali

2009-05-01

Full Text Available Salinity often suppresses the wheat performance. As wheat is designated as silicon (Si accumulator, hence Si application may alleviate the salinity induced damages. With the objective to combat the salinity stress in wheat by Si application (0, 50, 100, 150 and 200 mg L-1 using calcium silicate, an experiment was conducted on two contrasting wheat genotypes (salt sensitive; Auqab-2000 and salt tolerant; SARC-5 in salinized (10 dS m-1 and non-salinized (2 dS m-1 solutions. Plants were harvested 32 days after transplanting and evaluation was done on the basis of different morphological and analytical characters. Silicon supplementation into the solution culture improved wheat growth and K+/Na+ with reduced Na+ and enhanced K+ uptake. Concomitant improvement in shoot growth was observed; nonetheless the root growth remained unaffected by Si application. Better results were obtained with 150 and 200 mg L-1 of Si which were found almost equally effective. It was concluded that SARC-5 is better than Auqab-2000 against salt stress and Si inclusion into the solution medium is beneficial for wheat and can improve the crop growth both under optimal and salt stressful conditions.

Colloidal characterization of ultrafine silicon carbide and silicon nitride powders

Science.gov (United States)

Whitman, Pamela K.; Feke, Donald L.

1986-01-01

The effects of various powder treatment strategies on the colloid chemistry of aqueous dispersions of silicon carbide and silicon nitride are examined using a surface titration methodology. Pretreatments are used to differentiate between the true surface chemistry of the powders and artifacts resulting from exposure history. Silicon nitride powders require more extensive pretreatment to reveal consistent surface chemistry than do silicon carbide powders. As measured by titration, the degree of proton adsorption from the suspending fluid by pretreated silicon nitride and silicon carbide powders can both be made similar to that of silica.

Mg doping of GaN by molecular beam epitaxy

International Nuclear Information System (INIS)

Lieten, R R; Buchowicz, G; Dubon, O; Motsnyi, V; Zhang, L; Cheng, K; Leys, M; Degroote, S; Borghs, G

2011-01-01

We present a systematic study on the influence of growth conditions on the incorporation and activation of Mg in GaN layers grown by plasma-assisted molecular beam epitaxy. We show that high quality p-type GaN layers can be obtained on GaN-on-silicon templates. The Mg incorporation and the electrical properties have been investigated as a function of growth temperature, Ga : N flux ratio and Mg : Ga flux ratio. It was found that the incorporation of Mg and the electrical properties are highly sensitive to the Ga : N flux ratio. The highest hole mobility and lowest resistivity were achieved for slightly Ga-rich conditions. In addition to an optimal Ga : N ratio, an optimum Mg : Ga flux ratio was also observed at around 1%. We observed a clear Mg flux window for p-type doping of GaN : 0.31% 17 cm -3 and a mobility of 15 cm 2 V -1 s -1 . Temperature-dependent Hall effect measurements indicate an acceptor depth in these samples of 100 meV for a hole concentration of 5.5 x 10 17 cm -3 . The corresponding Mg concentration is 5 x 10 19 cm -3 , indicating approximately 1% activation at room temperature. In addition to continuous growth of Mg-doped GaN layers we also investigated different modulated growth procedures. We show that a modulated growth procedure has only limited influence on Mg doping at a growth temperature of 800 deg. or higher. This result is thus in contrast to previously reported GaN : Mg doping at much lower growth temperatures of 500 deg. C.

Arsenic implantation into polycrystalline silicon and diffusion to silicon substrate

International Nuclear Information System (INIS)

Tsukamoto, K.; Akasaka, Y.; Horie, K.

1977-01-01

Arsenic implantation into polycrystalline silicon and drive-in diffusion to silicon substrate have been investigated by MeV He + backscattering analysis and also by electrical measurements. The range distributions of arsenic implanted into polycrystalline silicon are well fitted to Gaussian distributions over the energy range 60--350 keV. The measured values of R/sub P/ and ΔR/sub P/ are about 10 and 20% larger than the theoretical predictions, respectively. The effective diffusion coefficient of arsenic implanted into polycrystalline silicon is expressed as D=0.63 exp[(-3.22 eV/kT)] and is independent of the arsenic concentration. The drive-in diffusion of arsenic from the implanted polycrystalline silicon layer into the silicon substrate is significantly affected by the diffusion atmosphere. In the N 2 atmosphere, a considerable amount of arsenic atoms diffuses outward to the ambient. The outdiffusion can be suppressed by encapsulation with Si 3 N 4 . In the oxidizing atmosphere, arsenic atoms are driven inward by growing SiO 2 due to the segregation between SiO 2 and polycrystalline silicon, and consequently the drive-in diffusion of arsenic is enhanced. At the interface between the polycrystalline silicon layer and the silicon substrate, arsenic atoms are likely to segregate at the polycrystalline silicon side

Porous silicon: silicon quantum dots for photonic applications

International Nuclear Information System (INIS)

Pavesi, L.; Guardini, R.

1996-01-01

Porous silicon formation and structure characterization are briefly illustrated. Its luminescence properties rae presented and interpreted on the basis of exciton recombination in quantum dot structures: the trap-controlled hopping mechanism is used to describe the recombination dynamics. Porous silicon application to photonic devices is considered: porous silicon multilayer in general, and micro cavities in particular are described. The present situation in the realization of porous silicon LEDs is considered, and future developments in this field of research are suggested. (author). 30 refs., 30 figs., 13 tabs

Effect of silicon and nanosilicon on reduction of damage caused by salt stress in maize (Zea mays seedlings

Directory of Open Access Journals (Sweden)

Assieh Behdad

2015-12-01

Full Text Available Salinity reduced the efficiency of agricultural production like maize as one of the most important cereals for food and oil for humans. Silicon is the second most abundant element in the soil and alleviates the biotic and abiotic stresses in plants. The aim of this study is evaluate the effect of silicon and nanosilicon on improvement of salt stress in maize (Zea mays. For this propose, the interaction between the effects of different levels of salinity (0 and 100 mM, silicon and nanosilicon (50, 100 and 150 mg /mL was studied in completely randomized block design with factorial experiments and with three replications. The results showed that salinity significantly decreased root and shoot growth, amount of chlorophyll and carotenoid pigments, protein and potassium contents, compared to control. Treating plants with silicon and nanosilicon caused reduction of salinity effects and increase above indices. Salinity stress also caused a significant increase in proline, anthocyanin and soluble carbohydrate contents, lipid peroxidation, and catalase activity and treatment with silicon and nanosilicon alleviates effects of salt stress and reduced the amount of above indices. 150 mg/mL of nanosilicon showed the maximum effect on diminishing negative effects of salt stress on all examined parameters. So, the use of this element is proposed as alleviator of salt stress on maize.

Mg2BIV: Narrow Bandgap Thermoelectric Semiconductors

Science.gov (United States)

Kim, Il-Ho

2018-05-01

Thermoelectric materials can convert thermal energy directly into electric energy and vice versa. The electricity generation from waste heat via thermoelectric devices can be considered as a new energy source. For instance, automotive exhaust gas and all industrial processes generate an enormous amount of waste heat that can be converted to electricity by using thermoelectric devices. Magnesium compound Mg2BIV (BIV = Si, Ge or Sn) has a favorable combination of physical and chemical properties and can be a good base for the development of new efficient thermoelectrics. Because they possess similar properties to those of group BIV elemental semiconductors, they have been recognized as good candidates for thermoelectric applications. Mg2Si, Mg2Ge and Mg2Sn with an antifluorite structure are narrow bandgap semiconductors with indirect band gaps of 0.77 eV, 0.74 eV, and 0.35 eV, respectively. Mg2BIV has been recognized as a promising material for thermoelectric energy conversion at temperatures ranging from 500 K to 800 K. Compared to other thermoelectric materials operating in the similar temperature range, such as PbTe and filled skutterudites, the important aspects of Mg2BIV are non-toxic and earth-abundant elements. Based on classical thermoelectric theory, the material factor β ( m* / m e)3/2μκ L -1 can be utilized as the criterion for thermoelectric material selection, where m* is the density-of-states effective mass, me is the mass of an electron, μ is the carrier mobility, and κL is the lattice thermal conductivity. The β for magnesium silicides is 14, which is very high compared to 0.8 for iron silicides, 1.4 for manganese silicides, and 2.6 for silicon-germanium alloys. In this paper, basic phenomena of thermoelectricity and transport parameters for thermoelectric materials were briefly introduced, and thermoelectric properties of Mg2BIV synthesized by using a solid-state reaction were reviewed. In addition, various Mg2BIV compounds were discussed

Silicon-Rich Silicon Carbide Hole-Selective Rear Contacts for Crystalline-Silicon-Based Solar Cells.

Science.gov (United States)

Nogay, Gizem; Stuckelberger, Josua; Wyss, Philippe; Jeangros, Quentin; Allebé, Christophe; Niquille, Xavier; Debrot, Fabien; Despeisse, Matthieu; Haug, Franz-Josef; Löper, Philipp; Ballif, Christophe

2016-12-28

The use of passivating contacts compatible with typical homojunction thermal processes is one of the most promising approaches to realizing high-efficiency silicon solar cells. In this work, we investigate an alternative rear-passivating contact targeting facile implementation to industrial p-type solar cells. The contact structure consists of a chemically grown thin silicon oxide layer, which is capped with a boron-doped silicon-rich silicon carbide [SiC x (p)] layer and then annealed at 800-900 °C. Transmission electron microscopy reveals that the thin chemical oxide layer disappears upon thermal annealing up to 900 °C, leading to degraded surface passivation. We interpret this in terms of a chemical reaction between carbon atoms in the SiC x (p) layer and the adjacent chemical oxide layer. To prevent this reaction, an intrinsic silicon interlayer was introduced between the chemical oxide and the SiC x (p) layer. We show that this intrinsic silicon interlayer is beneficial for surface passivation. Optimized passivation is obtained with a 10-nm-thick intrinsic silicon interlayer, yielding an emitter saturation current density of 17 fA cm -2 on p-type wafers, which translates into an implied open-circuit voltage of 708 mV. The potential of the developed contact at the rear side is further investigated by realizing a proof-of-concept hybrid solar cell, featuring a heterojunction front-side contact made of intrinsic amorphous silicon and phosphorus-doped amorphous silicon. Even though the presented cells are limited by front-side reflection and front-side parasitic absorption, the obtained cell with a V oc of 694.7 mV, a FF of 79.1%, and an efficiency of 20.44% demonstrates the potential of the p + /p-wafer full-side-passivated rear-side scheme shown here.

Enhancing shelf life of minimally processed multiplier onion using silicone membrane.

Science.gov (United States)

Naik, Ravindra; Ambrose, Dawn C P; Raghavan, G S Vijaya; Annamalai, S J K

2014-12-01

The aim of storage of minimal processed product is to increase the shelf life and thereby extend the period of availability of minimally processed produce. The silicone membrane makes use of the ability of polymer to permit selective passage of gases at different rates according to their physical and chemical properties. Here, the product stored maintains its own atmosphere by the combined effects of respiration process of the commodity and the diffusion rate through the membrane. A study was undertaken to enhance the shelf life of minimally processed multiplier onion with silicone membrane. The respiration activity was recorded at a temperature of 30 ± 2 °C (RH = 60 %) and 5 ± 1 °C (RH = 90 %). The respiration was found to be 23.4, 15.6, 10 mg CO2kg(-1)h(-1) at 5 ± 1 °C and 140, 110, 60 mg CO2kg(-1) h(-1) at 30 ± 2° for the peeled, sliced and diced multiplier onion, respectively. The respiration rate for the fresh multiplier onion was recorded to be 5, 10 mg CO2kg(-1) h(-1) at 5 ± 1 °C and 30 ± 1 ° C, respectively. Based on the shelf life studies and on the sensory evaluation, it was found that only the peeled multiplier onion could be stored. The sliced and diced multiplier onion did not have the required shelf life. The shelf life of the multiplier onion in the peel form could be increased from 4-5 days to 14 days by using the combined effect of silicone membrane (6 cm(2)/kg) and low temperature (5 ± 1 °C).

Geochemistry of silicon isotopes

Energy Technology Data Exchange (ETDEWEB)

Ding, Tiping; Li, Yanhe; Gao, Jianfei; Hu, Bin [Chinese Academy of Geological Science, Beijing (China). Inst. of Mineral Resources; Jiang, Shaoyong [China Univ. of Geosciences, Wuhan (China).

2018-04-01

Silicon is one of the most abundant elements in the Earth and silicon isotope geochemistry is important in identifying the silicon source for various geological bodies and in studying the behavior of silicon in different geological processes. This book starts with an introduction on the development of silicon isotope geochemistry. Various analytical methods are described and compared with each other in detail. The mechanisms of silicon isotope fractionation are discussed, and silicon isotope distributions in various extraterrestrial and terrestrial reservoirs are updated. Besides, the applications of silicon isotopes in several important fields are presented.

Sequential purification and crystal growth for the production of low cost silicon substrates. Quarterly technical progress report No. 1, 15 September 1979-31 December 1979

Energy Technology Data Exchange (ETDEWEB)

Liaw, M.; Secco, F.; Ingle, B.; Down, D.

1980-02-01

Over the past several years, Motorola's Materials Technology Laboratory (MTL), has been conducting several projects with goals directed at the production of high quality low cost silicon crystals. One of the projects which is being investigated is the direct purification of MG-Si. A unique characteristic of the approach used by this project is the use of a crystal puller to perform both purification and crystal growth. Sequential steps of purification were taken. By the completion of this series of purification, the purified MG-Si melt will be further purified by impurity redistribution using ingot pulling. The final purified silicon will be in an ingot form of desired dimensions for slicing into silicon sheets. The sequential steps of purification include: (1) leaching of MG-Si charge, (2) phase separation, (3) reactive gas treatment, (4) liquid-liquid extraction (called Slagging), and (5) purification by redistribution of impurities using ingot pulling. Progress on items (1) and (2) is reported. (WHK)

Porous silicon nanoparticle as a stabilizing support for chondroitinase.

Science.gov (United States)

Daneshjou, Sara; Dabirmanesh, Bahareh; Rahimi, Fereshteh; Khajeh, Khosro

2017-01-01

Chondroitinase ABCI (cABCI) from Proteus vulgaris is a drug enzyme that can be used to treat spinal cord injuries. One of the main problems of chondroitinase ABC1 is its low thermal stability. The objective of the current study was to stabilize the enzyme through entrapment within porous silicon (pSi) nanoparticles. pSi was prepared by an electrochemical etch of p-type silicon using hydrofluoric acid/ethanol. The size of nanoparticles were determined 180nm by dynamic light scattering and the mean pore diameter was in the range of 40-60nm obtained by scanning electron microscopy. Enzymes were immobilized on porouse silicon nanoparticles by entrapment. The capacity of matrix was 35μg enzyme per 1mg of silicon. The immobilized enzyme displayed lower V max values compared to the free enzyme, but Km values were the same for both enzymes. Immobilization significantly increased the enzyme stability at various temperatures (-20, 4, 25 and 37°C). For example, at 4°C, the free enzyme (in 10mM imidazole) retained 20% of its activity after 100min, while the immobilized one retained 50% of its initial activity. Nanoparticles loading capacity and the enzyme release rate showed that the selected particles could be a pharmaceutically acceptable carrier for chondroitinase. Copyright © 2016 Elsevier B.V. All rights reserved.

Simulation and analysis of Au-MgF2 structure in plasmonic sensor in near infrared spectral region

Science.gov (United States)

Sharma, Anuj K.

2018-05-01

Plasmonic sensor based on metal-dielectric combination of gold and MgF2 layers is studied in near infrared (NIR) spectral region. An emphasis is given on the effect of variable thickness of MgF2 layer in combination with operating wavelength and gold layer thickness on the sensor's performance in NIR. It is established that the variation in MgF2 thickness in connection with plasmon penetration depth leads to significant variation in sensor's performance. The analysis leads to a conclusion that taking smaller values of MgF2 layer thickness and operating at longer NIR wavelength leads to enhanced sensing performance. Also, fluoride glass can provide better sensing performance than chalcogenide glass and silicon substrate.

Crystal chemistry of six-coordinated silicon: A key to understanding the earth's deep interior

International Nuclear Information System (INIS)

Finger, L.W.; Hazen, R.M.

1991-01-01

A survey of high-pressure silicates reveals 12 distinct high-density structural topologies with octahedral Si. Seven of these structure types - stishovite, perovskite, ilmenite, hollandite, calcium ferrite, pyrochlore and K 2 NiF 4 type - contain only six-corrdinated silicon. Other high-pressure silicates, including those with the garnet, pyroxene, wadeite, anhydrous phase B and phase B structures, contain both tetrahedral and octahedral Si. Five systematic trends among these dozen structures suggest the existence of other, as yet unobserved, possible mantle Si phases. The criteria are: (1) Structures like rutile, hollandite and calcium ferrite formed from edge-sharing chains of silicon octahedra; (2) germanates synthesized at room pressure with octahedral Ge; (3) isomorphs of room-pressure oxides with 3+ or 4+ transition-metal cations; (4) high-pressure magnesium silicates related to room-pressure aluminates by the substitution 2Al→Mg+Si; and (5) the homologous structures in system Mg-Si-O-H that includes phase B and anhydrous phase B. Each of these criteria can be used to predict other potential octahedral Si phases. Of special interest are predicted structure types that fulfill more than one criterion: Diaspore-type (MgSi)O 2 (OH) 2 , aerugite-type Mg 10 Si 3 O 16 , sphene-type CaSi 2 O 5 , benitoite-type BaSi 4 O 9 , gibbsite-type MgSi(OH) 6 and pseudobrookite-type Fe 2 SiO 5 . (orig.)

The potential of postharvest silicon dips to regulate phenolics in ...

African Journals Online (AJOL)

This study investigated the ability of silicon dips to enhance the phenolic content in order to reduce the incidence of chilling injury in lemon fruit. Fruits were obtained from two farms and dipped in 0, 50, 150 and 250 mg L-1 solutions of K2SiO3 for 30 min and afterward, fruit were air dried and waxed. Thereafter, fruits were ...

Silicon heterojunction transistor

International Nuclear Information System (INIS)

Matsushita, T.; Oh-uchi, N.; Hayashi, H.; Yamoto, H.

1979-01-01

SIPOS (Semi-insulating polycrystalline silicon) which is used as a surface passivation layer for highly reliable silicon devices constitutes a good heterojunction for silicon. P- or B-doped SIPOS has been used as the emitter material of a heterojunction transistor with the base and collector of silicon. An npn SIPOS-Si heterojunction transistor showing 50 times the current gain of an npn silicon homojunction transistor has been realized by high-temperature treatments in nitrogen and low-temperature annealing in hydrogen or forming gas

Effect of silicon application on physiological characteristics and growth of wheat (Triticum aestivum L. under drought stress condition

Directory of Open Access Journals (Sweden)

A. Karmollachaab

2016-05-01

Full Text Available In order to investigate the effect of silicon application on some physiological characteristics and growth of Wheat (Triticum aestivum L. under late drought stress condition, an experiment was conducted at the Agriculture and Natural Resources University of Ramin, Khuzestan during year 2012. The experiment was conducted in the open environment as factorial randomized complete block design with three levels of drought stress (irrigation after 25, 50 and 75% depletion of available water content as the first factor and four levels of silicon (0, 10, 20 and 30 mg Si.kg-1 soil as the second factor with three replications. The results showed that drought stress imposed a negative significant effect on all traits. The drought stress led to increased electrolyte leakage and proline content, cuticular wax, leaf silicon concentration, superoxide dismutase activity (SOD and grain potassium were decreased. The severe drought stress has most effect on electrolyte leakage (up to 53%. The application of silicon except the shoot/root parameter, on all characters have been affected so that application of 30 mg Si.kg-1 soil led to decrease electrolyte leakage up to 22.5% and increased SOD activity, proline content, cuticular wax grain K and flag leaf Si concentration, 25, 12.8, 21, 17 and 30% compared to control, respectively. In general, the results showed a positive effect of silicon on wheat plant under stress conditions that were higher than no stress condition.

Leaching of assimilable silicon species from fly ash

International Nuclear Information System (INIS)

Piekos, R.; Paslawska, S.

1998-01-01

The objective of this study was to investigate the leaching of assimilable silicon species from coal fly ash with distilled water, sea waterand synthetic sea water at various fly ash/water ratios, pHs and temperatures. At the 1 g/100 ml fly ash/water ratio, less than 1 mg Si was found in 11 of aqueous slurries over the pH range 4-8 after 2 h at ambient temperature. The leaching was most effective at pH 10.5. At the fly ash/waterratio indicated, the pH of the suspensions decreased from 10.4 to 8.4 after 5days. The pH of fly ash slurries in sea water varied only slightly over time as compared with that in distilled water. Generally, the leaching of assimilable silicon species with distilled water was more intense than that with the sea water. 27 refs., 6 figs., 3 tabs

Study of electron-beam-evaporated MgO films using electron diffraction, optical absorption and cathodoluminescence

Energy Technology Data Exchange (ETDEWEB)

Aboelfotoh, M.O.; Ramsey, J.N.

1982-05-21

Reflection high energy electron diffraction, optical absorption and cathodoluminescence were used to study MgO films deposited onto fused silica, single-crystal silicon and LiF substrates at various temperatures. Results showed that some of the same optical absorption and emission bands observed in X- or UV-irradiated, additively colored or mechanically deformed MgO crystals were observed in evaporated MgO films. The peak positions and the relative peak intensities of the optical absorption and emission bands depended on the substrate temperature during film deposition as well as on the structure of the film. The effect of heating the films in air and vacuum on the optical absorption and emission bands is also discussed.

Suppression of Mg propagation into subsequent layers grown by MOCVD

Science.gov (United States)

Agarwal, Anchal; Tahhan, Maher; Mates, Tom; Keller, Stacia; Mishra, Umesh

2017-01-01

Low temperature (LT) flow modulation epitaxy (FME) or "pulsed" growth was successfully used to prevent magnesium from Metalorganic Chemical Vapor Deposition (MOCVD) grown p-GaN:Mg layers riding into subsequently deposited n-type layers. Mg concentration in the subsequent layers was lowered from ˜1 × 1018 cm-3 for a medium temperature growth at 950 °C to ˜1 × 1016 cm-3 for a low temperature growth at 700 °C via FME. The slope of the Mg concentration drop in the 700 °C FME sample was 20 nm/dec—the lowest ever demonstrated by MOCVD. For growth on Mg implanted GaN layers, the drop for a medium temperature regrowth at 950 °C was ˜10 nm/dec compared to >120 nm/dec for a high temperature regrowth at 1150 °C. This drop-rate obtained at 950 °C or lower was maintained even when the growth temperature in the following layers was raised to 1150 °C. A controlled silicon doping series using LT FME was also demonstrated with the lowest and highest achieved doping levels being 5 × 1016 cm-3 and 6 × 1019 cm-3, respectively.

Microstructure and Mechanical Properties of Al-5Mg-0.8Mn Alloys with Various Contents of Fe and Si Cast under Near-Rapid Cooling

Directory of Open Access Journals (Sweden)

Yulin Liu

2017-10-01

Full Text Available Al-5Mg-0.8Mn alloys (AA5083 with various iron and silicon contents were cast under near-rapid cooling and rolled into sheets. The aim was to study the feasibility of minimizing the deteriorating level of the harmful Fe-rich phases on the mechanical properties through refining the intermetallics by significantly increasing the casting rate. The results showed that the size and density of the intermetallic particles that remained in the hot bands and the cold rolled sheets increased as the contents of iron and silicon in the alloys were increased. However, the increment of the particle sizes was limited due to the significant refinement of the intermetallics formed during casting under near-rapid cooling. The mechanical properties of the alloys reduced as the contents of iron and silicon in the alloys increased. However, the decrement of tensile strengths and ductility was quite small. Therefore, higher contents of iron and silicon could be used in the Al-5Mg-0.8Mn alloy (AA5083 alloy when the material is cast under near-rapid cooling, such as in the continuous strip casting process.

The Rechargeability of Silicon-Air Batteries

Science.gov (United States)

2012-06-01

an Si-air electrochemical cell a source of water for other applications. Metal-air batteries, silicon-air, electrochemistry , rechargeable batteries UU...be based on constant amount of water in the IL.  The electrochemistry has to be based on more robust reference electrode. Some use of ferrocence...MgO  -569.4  -601.7  3942  6859  Zn  Zn + 1/2O2 ZnO   -320.8  -350.7  1363  9677  Si  Si + O2 SiO2  -856.5  -910.9  8470  21090  7 electrode. RTIL

Vertical integration of high-Q silicon nitride microresonators into silicon-on-insulator platform.

Science.gov (United States)

Li, Qing; Eftekhar, Ali A; Sodagar, Majid; Xia, Zhixuan; Atabaki, Amir H; Adibi, Ali

2013-07-29

We demonstrate a vertical integration of high-Q silicon nitride microresonators into the silicon-on-insulator platform for applications at the telecommunication wavelengths. Low-loss silicon nitride films with a thickness of 400 nm are successfully grown, enabling compact silicon nitride microresonators with ultra-high intrinsic Qs (~ 6 × 10(6) for 60 μm radius and ~ 2 × 10(7) for 240 μm radius). The coupling between the silicon nitride microresonator and the underneath silicon waveguide is based on evanescent coupling with silicon dioxide as buffer. Selective coupling to a desired radial mode of the silicon nitride microresonator is also achievable using a pulley coupling scheme. In this work, a 60-μm-radius silicon nitride microresonator has been successfully integrated into the silicon-on-insulator platform, showing a single-mode operation with an intrinsic Q of 2 × 10(6).

Analytical and Experimental Evaluation of Joining Silicon Carbide to Silicon Carbide and Silicon Nitride to Silicon Nitride for Advanced Heat Engine Applications Phase II

Energy Technology Data Exchange (ETDEWEB)

Sundberg, G.J.

1994-01-01

Techniques were developed to produce reliable silicon nitride to silicon nitride (NCX-5101) curved joins which were used to manufacture spin test specimens as a proof of concept to simulate parts such as a simple rotor. Specimens were machined from the curved joins to measure the following properties of the join interlayer: tensile strength, shear strength, 22 C flexure strength and 1370 C flexure strength. In parallel, extensive silicon nitride tensile creep evaluation of planar butt joins provided a sufficient data base to develop models with accurate predictive capability for different geometries. Analytical models applied satisfactorily to the silicon nitride joins were Norton's Law for creep strain, a modified Norton's Law internal variable model and the Monkman-Grant relationship for failure modeling. The Theta Projection method was less successful. Attempts were also made to develop planar butt joins of siliconized silicon carbide (NT230).

Electrical leakage phenomenon in heteroepitaxial cubic silicon carbide on silicon

Science.gov (United States)

Pradeepkumar, Aiswarya; Zielinski, Marcin; Bosi, Matteo; Verzellesi, Giovanni; Gaskill, D. Kurt; Iacopi, Francesca

2018-06-01

Heteroepitaxial 3C-SiC films on silicon substrates are of technological interest as enablers to integrate the excellent electrical, electronic, mechanical, thermal, and epitaxial properties of bulk silicon carbide into well-established silicon technologies. One critical bottleneck of this integration is the establishment of a stable and reliable electronic junction at the heteroepitaxial interface of the n-type SiC with the silicon substrate. We have thus investigated in detail the electrical and transport properties of heteroepitaxial cubic silicon carbide films grown via different methods on low-doped and high-resistivity silicon substrates by using van der Pauw Hall and transfer length measurements as test vehicles. We have found that Si and C intermixing upon or after growth, particularly by the diffusion of carbon into the silicon matrix, creates extensive interstitial carbon traps and hampers the formation of a stable rectifying or insulating junction at the SiC/Si interface. Although a reliable p-n junction may not be realistic in the SiC/Si system, we can achieve, from a point of view of the electrical isolation of in-plane SiC structures, leakage suppression through the substrate by using a high-resistivity silicon substrate coupled with deep recess etching in between the SiC structures.

Fluorescence and thermoluminescence in silicon oxide films rich in silicon

International Nuclear Information System (INIS)

Berman M, D.; Piters, T. M.; Aceves M, M.; Berriel V, L. R.; Luna L, J. A.

2009-10-01

In this work we determined the fluorescence and thermoluminescence (TL) creation spectra of silicon rich oxide films (SRO) with three different silicon excesses. To study the TL of SRO, 550 nm of SRO film were deposited by Low Pressure Chemical Vapor Deposition technique on N-type silicon substrates with resistivity in the order of 3 to 5 Ω-cm with silicon excess controlled by the ratio of the gases used in the process, SRO films with Ro= 10, 20 and 30 (12-6% silicon excess) were obtained. Then, they were thermally treated in N 2 at high temperatures to diffuse and homogenize the silicon excess. In the fluorescence spectra two main emission regions are observed, one around 400 nm and one around 800 nm. TL creation spectra were determined by plotting the integrated TL intensity as function of the excitation wavelength. (Author)

Corrosion behaviour of groundnut shell ash and silicon carbide hybrid reinforced Al-Mg-Si alloy matrix composites in 3.5% NaCl and 0.3M H2SO4 solutions

Directory of Open Access Journals (Sweden)

Kenneth Kanayo ALANEME

2015-05-01

Full Text Available The corrosion behaviour of Al-Mg-Si alloy based composites reinforced with groundnut shell ash (GSA and silicon carbide (SiC was investigated. The aim is to assess the corrosion properties of Al-Mg-Si alloy based hybrid reinforced composites developed using different mix ratios of GSA (a cheaply processed agro waste derivative which served as partial replacement for SiC and SiC as reinforcing materials. GSA and SiC mixed in weight ratios 0:1, 1:3, 1:1, 3:1, and 1:0 were utilized to prepare 6 and 10 wt% of the reinforcing phase with Al‐Mg‐Si alloy as matrix using two‐step stir casting method. Mass loss and corrosion rate measurement was used to study the corrosion behaviour of the produced composites in 3.5% NaCl and 0.3M H2SO4 solutions. The results show that the Al-Mg-Si alloy based composites containing 6 and 10 wt% GSA and SiC in varied weight ratios were resistant to corrosion in 3.5% NaCl solution. The composites were however more susceptible to corrosion in 0.3M H2SO4 solution (in comparison with the 3.5% NaCl solution. It was noted that the Al-Mg-Si/6 wt% GSA-SiC hybrid composite grades containing GSA and SiC in weight ratio 1:3 and 3:1 respectively exhibited superior corrosion resistance in the 0.3M H2SO4 solution compared to other composites produced for this series. In the case of the Al-Mg-Si/10 wt% GSA-SiC hybrid composite grades, the corrosion resistance was relatively superior for the composites containing a greater weight ratio of GSA (75% and 100% in 0.3M H2SO4 solution.

Buried oxide layer in silicon

Science.gov (United States)

Sadana, Devendra Kumar; Holland, Orin Wayne

2001-01-01

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Microstructural stability concerning a potential nuclear use of Al-Mg-Si

International Nuclear Information System (INIS)

Urreta de Pereyra, S.E.

1990-01-01

Mechanical properties and microstructures in an Al-Mg-Si alloy (6061) are known to change during irradiation. Many authors report that mechanical strength reduces after irradiation and that the main cause of this drastic softening was shown to be the dissolution of hardening precipitates. In this work, the stability of needle-shaped precipitates before irradiation is studied. Evidence is provided to suggest that β' may not transform directly in β ' by growth, but that another nucleation event is necessary. For concentrations of about 1wt% Mg 2 Si, accidental reversion treatments of short times above 250 deg C are found to lead to a catastrophic drop in strength as a result of β' phase dissolution without simultaneous precipitation of β ' . It was also found that these phases may differ in composition as well as in structure as reported in the literature. Small precipitates are found in grain boundaries that are richer in silicon than the equilibrium phase Mg 2 Si. (Author)

Ion beam studied of silicon oxynitride and silicon nitroxide thin layers

International Nuclear Information System (INIS)

Oude Elferink, J.B.

1989-01-01

In this the processes occurring during high temperature treatments of silicon oxynitride and silicon oxide layers are described. Oxynitride layers with various atomic oxygen to nitrogen concentration ration (O/N) are considered. The high energy ion beam techniques Rutherford backscattering spectroscopy, elastic recoil detection and nuclear reaction analysis have been used to study the layer structures. A detailed discussion of these ion beam techniques is given. Numerical methods used to obtain quantitative data on elemental compositions and depth profiles are described. The electrical compositions and depth profiles are described. The electrical properties of silicon nitride films are known to be influenced by the behaviour of hydrogen in the film during high temperature anneling. Investigations of the behaviour of hydrogen are presented. Oxidation of silicon (oxy)nitride films in O 2 /H 2 0/HCl and nitridation of silicon dioxide films in NH 3 are considered since oxynitrides are applied as an oxidation mask in the LOCOS (Local oxidation of silicon) process. The nitridation of silicon oxide layers in an ammonia ambient is considered. The initial stage and the dependence on the oxide thickness of nitrogen and hydrogen incorporation are discussed. Finally, oxidation of silicon oxynitride layers and of silicon oxide layers are compared. (author). 76 refs.; 48 figs.; 1 tab

Nonlinear silicon photonics

Science.gov (United States)

Tsia, Kevin K.; Jalali, Bahram

2010-05-01

An intriguing optical property of silicon is that it exhibits a large third-order optical nonlinearity, with orders-ofmagnitude larger than that of silica glass in the telecommunication band. This allows efficient nonlinear optical interaction at relatively low power levels in a small footprint. Indeed, we have witnessed a stunning progress in harnessing the Raman and Kerr effects in silicon as the mechanisms for enabling chip-scale optical amplification, lasing, and wavelength conversion - functions that until recently were perceived to be beyond the reach of silicon. With all the continuous efforts developing novel techniques, nonlinear silicon photonics is expected to be able to reach even beyond the prior achievements. Instead of providing a comprehensive overview of this field, this manuscript highlights a number of new branches of nonlinear silicon photonics, which have not been fully recognized in the past. In particular, they are two-photon photovoltaic effect, mid-wave infrared (MWIR) silicon photonics, broadband Raman effects, inverse Raman scattering, and periodically-poled silicon (PePSi). These novel effects and techniques could create a new paradigm for silicon photonics and extend its utility beyond the traditionally anticipated applications.

Liquid phase epitaxial growth of silicon on porous silicon for photovoltaic applications

International Nuclear Information System (INIS)

Berger, S.; Quoizola, S.; Fave, A.; Kaminski, A.; Perichon, S.; Barbier, D.; Laugier, A.

2001-01-01

The aim of this experiment is to grow a thin silicon layer ( 2 atmosphere, and finally LPE silicon growth with different temperature profiles in order to obtain a silicon layer on the sacrificial porous silicon (p-Si). We observed a pyramidal growth on the surface of the (100) porous silicon but the coalescence was difficult to obtain. However, on a p-Si (111) oriented wafer, homogeneous layers were obtained. (orig.)

Assessment of the effect of silicon on antioxidant enzymes in cotton plants by multivariate analysis.

Science.gov (United States)

Alberto Moldes, Carlos; Fontão de Lima Filho, Oscar; Manuel Camiña, José; Gabriela Kiriachek, Soraya; Lia Molas, María; Mui Tsai, Siu

2013-11-27

Silicon has been extensively researched in relation to the response of plants to biotic and abiotic stress, as an element triggering defense mechanisms which activate the antioxidant system. Furthermore, in some species, adding silicon to unstressed plants modifies the activity of certain antioxidant enzymes participating in detoxifying processes. Thus, in this study, we analyzed the activity of antioxidant enzymes in leaves and roots of unstressed cotton plants fertilized with silicon (Si). Cotton plants were grown in hydroponic culture and added with increasing doses of potassium silicate; then, the enzymatic activity of catalase (CAT), guaiacol peroxidase (GPOX), ascorbate peroxidase (APX), and lipid peroxidation were determined. Using multivariate analysis, we found that silicon altered the activity of GPOX, APX, and CAT in roots and leaves of unstressed cotton plants, whereas lipid peroxidation was not affected. The analysis of these four variables in concert showed a clear differentiation among Si treatments. We observed that enzymatic activities in leaves and roots changed as silicon concentration increased, to stabilize at 100 and 200 mg Si L(-1) treatments in leaves and roots, respectively. Those alterations would allow a new biochemical status that could be partially responsible for the beneficial effects of silicon. This study might contribute to adjust the silicon application doses for optimal fertilization, preventing potential toxic effects and unnecessary cost.

Effect of samarium (Sm) addition on the microstructures and mechanical properties of Al–7Si–0.7Mg alloys

International Nuclear Information System (INIS)

Qiu, Hongxu; Yan, Hong; Hu, Zhi

2013-01-01

Highlights: •Sm affected the secondary dendrite arm spacing of Al–7Si–0.7Mg alloy. •The coarse plate-like eutectic silicon was fully modified into a fine branched and particle structure when 0.6 wt.% Sm added. •The tensile properties were enhanced by the addition of Sm. •Sm has marked effects on eutectic temperature and the latent heat ΔH R on remelting behavior. •The morphology and chemical composition of Sm-rich intermetallics were studied. -- Abstract: The effects of samarium (Sm) additions (0–0.9 wt.%) on the microstructures and mechanical properties of Al–7Si–0.7Mg alloys have been studied in this article. The microstructures of the as-cast samples were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The experimental results indicated that the rare earth Sm affected the secondary dendrite arm spacing (SDAS) of Al–7Si–0.7Mg alloy. And it was found that Sm had great modification effects on the microstructures of eutectic silicon. When 0.6 wt.% Sm was added to the alloy, the coarse plate-like eutectic silicon was fully modified into a fine fibrous structure; the dendrites of Al–7Si–0.7Mg alloy was best refined. The mechanical properties were investigated by tensile test. The findings indicate that the tensile properties and elongation were improved by the addition of Sm. And a good combination of ultimate tensile strength (215 MPa) and elongation (3.3%) was obtained when the Sm addition was up to 0.6 wt.%. Furthermore the results of thermal analysis reveal that Sm addition had marked effects on eutectic temperature and the latent heat ΔH R on remelting behavior

Crystal spectroscopy of silicon aero-gel end-caps driven by a dynamic hohlraum on Z

International Nuclear Information System (INIS)

Nash, T.J.; Sanford, T.W.L.; Mock, R.C.; Leeper, R.J.; Chandler, G.A.; Bailey, J.E.; McKenney, J.L.; Mehlhorn, T.A.; Seaman, J.F.; McGurn, J.; Schroen, D.; Russell, C.; Lake, P.E.; Jobe, D.O.; Gilliland, T.; Nielsen, D.S.; Lucas, J.; Moore, T.; Torres, J.A.; MacFarlane, J.J.; Apruzese, J.P.; Chrien, R.; Idzorek, G.; Peterson, D.L.; Watt, R.

2005-01-01

We present results from crystal spectroscopic analysis of silicon aero-gel foams heated by dynamic hohlraums on Z. The dynamic hohlraum on Z creates a radiation source with a 230-eV average temperature over a 2.4-mm diameter. In these experiments silicon aero-gel foams with 10-mg/cm3 densities and 1.7-mm lengths were placed on both ends of the dynamic hohlraum. Several crystal spectrometers were placed both above and below the z-pinch to diagnose the temperature of the silicon aero-gel foam using the K-shell lines of silicon. The crystal spectrometers were (1) temporally integrated and spatially resolved, (2) temporally resolved and spatially integrated, and (3) both temporally and spatially resolved. The results indicate that the dynamic hohlraum heats the silicon aero-gel to approximately 150-eV at peak power. As the dynamic hohlraum source cools after peak power the silicon aero-gel continues to heat and jets axially at an average velocity of approximately 50-cm/μs. The spectroscopy has also shown that the reason for the up/down asymmetry in radiated power on Z is that tungsten enters the line-of-sight on the bottom of the machine much more than on the top

Fast determination of impurities in metallurgical grade silicon for photovoltaics by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Hampel, J.; Boldt, F.M.; Gerstenberg, H.; Hampel, G.; Kratz, J.V.; Reber, S.; Wiehl, N.

2011-01-01

Standard wafer solar cells are made of near-semiconductor quality silicon. This high quality material makes up a significant part of the total costs of a solar module. Therefore, new concepts with less expensive so called solar grade silicon directly based on physiochemically upgraded metallurgical grade silicon are investigated. Metallurgical grade silicon contains large amounts of impurities, mainly transition metals like Fe, Cr, Mn, and Co, which degrade the minority carrier lifetime and thus the solar cell efficiency. A major reduction of the transition metal content occurs during the unidirectional crystallization due to the low segregation coefficient between the solid and liquid phase. A further reduction of the impurity level has to be done by gettering procedures applied to the silicon wafers. The efficiency of such cleaning procedures of metallurgical grade silicon is studied by instrumental neutron activation analysis (INAA). Small sized silicon wafers of approximately 200 mg with and without gettering step were analyzed. To accelerate the detection of transition metals in a crystallized silicon ingot, experiments of scanning whole vertical silicon columns with a diameter of approximately 1 cm by gamma spectroscopy were carried out. It was demonstrated that impurity profiles can be obtained in a comparably short time. Relatively constant transition metal ratios were found throughout an entire silicon ingot. This led to the conclusion that the determination of several metal profiles might be possible by the detection of only one 'leading element'. As the determination of Mn in silicon can be done quite fast compared to elements like Fe, Cr, and Co, it could be used as a rough marker for the overall metal concentration level. Thus, a fast way to determine impurities in photovoltaic silicon material is demonstrated. - Highlights: → We demonstrate a fast way to determine impurities in photovoltaic silicon by NAA. → We make first experiments of locally

Dietary Silicon Intake of Korean Young Adult Males and Its Relation to their Bone Status.

Science.gov (United States)

Choi, Mi-Kyeong; Kim, Mi-Hyun

2017-03-01

Accumulated data suggests a positive effect of silicon on bone health; however, limited research exists on the silicon content of foods. To further the understanding of the relationship between dietary silicon intake and bone health, a food composition database of commonly consumed foods in Korea is required. For quantitative data on the intake levels of silicon, we analyzed the silicon content of 365 food items commonly consumed in Korea using inductively coupled plasma-atomic emission spectrometry following microwave-assisted digestion. To investigate the dietary silicon intake status and to examine the potential role of dietary silicon intake in the bone status of men, a total of 400 healthy Korean adult males aged 19-25 were observed for their diet intake and calcaneus bone density using the 24-h recall method and quantitative ultrasound, respectively. Clinical markers reflecting bone metabolism such as serum total alkaline phosphatase, N-mid osteocalcin, and type 1 collagen C-terminal telopeptide concentrations were also analyzed. Silicon intake of the subjects was estimated as 37.5 ± 22.2 mg/day. Major food sources of dietary silicon in the Korean male were cereal and cereal products (25.6 % of total silicon intake), vegetables (22.7 %), beverages and liquors (21.2 %), and milk and milk products (7.0 %). Silicon intake correlated positively with age, weight, energy intake, protein intake, calcium intake, and alcohol intake. After adjusted for age, weight, energy intake, protein intake, calcium intake, alcohol intake, smoking cigarettes, and regular exercise status, daily total silicon intake had no correlation with calcaneus bone density and the bone metabolism markers, but silicon intake from vegetables had a positive correlation with serum total alkaline phosphatase activity, a bone formation maker. These findings show the possible positive relationship between dietary silicon intake from vegetables and the bone formation of young adult males. Further

Polycrystalline Silicon: a Biocompatibility Assay

International Nuclear Information System (INIS)

Pecheva, E.; Fingarova, D.; Pramatarova, L.; Hikov, T.; Laquerriere, P.; Bouthors, Sylvie; Dimova-Malinovska, D.; Montgomery, P.

2010-01-01

Polycrystalline silicon (poly-Si) layers were functionalized through the growth of biomimetic hydroxyapatite (HA) on their surface. HA is the mineral component of bones and teeth and thus possesses excellent bioactivity and biocompatibility. MG-63 osteoblast-like cells were cultured on both HA-coated and un-coated poly-Si surfaces for 1, 3, 5 and 7 days and toxicity, proliferation and cell morphology were investigated. The results revealed that the poly-Si layers were bioactive and compatible with the osteoblast-like cells. Nevertheless, the HA coating improved the cell interactions with the poly-Si surfaces based on the cell affinity to the specific chemical composition of the bone-like HA and/or to the higher HA roughness.

On the way to enhance the optical absorption of a-Si in NIR by embedding Mg_2Si thin film

International Nuclear Information System (INIS)

Chernev, I. M.; Shevlyagin, A. V.; Galkin, K. N.; Stuchlik, J.; Remes, Z.; Fajgar, R.; Galkin, N. G.

2016-01-01

Mg_2Si thin film was embedded in amorphous silicon matrix by solid phase epitaxy. The structure and optical properties were investigated by electron energy loss, X-ray photoelectron, Raman, and photo thermal deflection spectroscopy measurements. It was found that in the photon energy range of 0.8–1.7 eV, the light absorption of the structure with magnesium silicide (Mg_2Si) film embedded in a-Si(i) matrix is 1.5 times higher than that for the same structure without Mg_2Si.

Nonlinear silicon photonics

Science.gov (United States)

Borghi, M.; Castellan, C.; Signorini, S.; Trenti, A.; Pavesi, L.

2017-09-01

Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms as the dominant electronics industry. After twenty years of fervid development, silicon photonics is entering the market with low cost, high performance and mass-manufacturable optical devices. Until now, most silicon photonic devices have been based on linear optical effects, despite the many phenomenologies associated with nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review to describe the state-of-the-art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described—including frequency generation, frequency conversion, frequency-comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, and comb spectroscopy. Emerging quantum photonics applications, such as entangled photon sources, heralded single-photon sources and integrated quantum photonic circuits are also addressed at the end of this review.

Transformational silicon electronics

KAUST Repository

Rojas, Jhonathan Prieto

2014-02-25

In today\\'s traditional electronics such as in computers or in mobile phones, billions of high-performance, ultra-low-power devices are neatly integrated in extremely compact areas on rigid and brittle but low-cost bulk monocrystalline silicon (100) wafers. Ninety percent of global electronics are made up of silicon. Therefore, we have developed a generic low-cost regenerative batch fabrication process to transform such wafers full of devices into thin (5 μm), mechanically flexible, optically semitransparent silicon fabric with devices, then recycling the remaining wafer to generate multiple silicon fabric with chips and devices, ensuring low-cost and optimal utilization of the whole substrate. We show monocrystalline, amorphous, and polycrystalline silicon and silicon dioxide fabric, all from low-cost bulk silicon (100) wafers with the semiconductor industry\\'s most advanced high-κ/metal gate stack based high-performance, ultra-low-power capacitors, field effect transistors, energy harvesters, and storage to emphasize the effectiveness and versatility of this process to transform traditional electronics into flexible and semitransparent ones for multipurpose applications. © 2014 American Chemical Society.

Silicon Microspheres Photonics

International Nuclear Information System (INIS)

Serpenguzel, A.

2008-01-01

Electrophotonic integrated circuits (EPICs), or alternatively, optoelectronic integrated circuit (OEICs) are the natural evolution of the microelectronic integrated circuit (IC) with the addition of photonic capabilities. Traditionally, the IC industry has been based on group IV silicon, whereas the photonics industry on group III-V semiconductors. However, silicon based photonic microdevices have been making strands in siliconizing photonics. Silicon microspheres with their high quality factor whispering gallery modes (WGMs), are ideal candidates for wavelength division multiplexing (WDM) applications in the standard near-infrared communication bands. In this work, we will discuss the possibility of using silicon microspheres for photonics applications in the near-infrared

Exploring the island of inversion with the d({sup 30}Mg,p){sup 31}Mg reaction

Energy Technology Data Exchange (ETDEWEB)

Bildstein, Vinzenz

2010-12-07

In this thesis the results of a d({sup 30}Mg,p){sup 31}Mg experiment at REX-ISOLDE are presented. {sup 31}Mg is located directly on the border of the so-called ''Island of Inversion'', a region of the nuclear chart around {sup 32}Mg where deformed intruder states of the fp shell form the ground states of the nuclei instead of the normal spherical states of the sd shell. A recent experiment has shown the ground state of {sup 31}Mg to be a 1/2{sup +} state and indicates more than 90% intruder configuration. The question whether the low-lying excited states of {sup 31}Mg are deformed intruder states as well or rather spherical states from the sd shell, indicating shape coexistence, is still open. The d({sup 30}Mg,p) {sup 31}Mg reaction is thus a good tool to gain more insight into the nature of the Island of Inversion. In the framework of this thesis the angular distribution of protons was measured for the second excited state at 221 keV in coincidence with de-excitation {gamma}-rays. The angular distribution was compared to DWBA calculations for different transferred orbital momenta, identifying the state for the first time as an l=1 state. The experiment was performed with the new charged particle detector setup T-REX. The setup is optimized for transfer reactions with radioactive beams in inverse kinematics. T-REX was developed, built, installed, and used for this first one neutron transfer experiment in the context of this thesis. The T-REX setup consists of {delta}E-E{sub Rest} telescopes made out of position sensitive silicon detectors that cover almost 4{pi} of the solid angle and can be combined with the MINIBALL {gamma}-ray detector array. It has a large solid angle for the detection and identification of the light recoils from transfer reactions. T-REX allows in combination with the MINIBALL Germanium detector array the tagging of the excited states by their characteristic {gamma}-rays. The combination of T-REX and MINIBALL achieves an

Extraction-spectrophotometric method for silicon determination in high-purity substances. 2. Silicon determination in cadmium

Energy Technology Data Exchange (ETDEWEB)

Yudelevich, I G; Shaburova, V P; Shamrina, L V [AN SSSR, Novosibirsk (USSR). Inst. Neorganicheskoj Khimii

1989-01-01

Cadmium extraction by tributyl phosphate and trialkylbenzylammonium chloride (TABAC) depending on acid (HCl, HI), extracting agent concentration, volume of aqueous and organic phases, number of extraction steps is investigated. On the basis of the obtained results the spectrophotometric method for silicon determination in cadmium and CdCl/sub 2/ using malachite green with preliminary extraction of the base by the TABAC from HCl solutions. The method detection limit is 3.9x10/sup -4/ % Si with respect to initial cadmium sample of 100 mg and 7.8x10/sup -5/ % with respect to 0.5 g of CdCl/sub 2/. The relative standard deviation is S/sub r/-0.07-0.13.

Production of technical silicon and silicon carbide from rice-husk

Directory of Open Access Journals (Sweden)

A. Z. Issagulov

2014-10-01

Full Text Available In the article there are studied physical and chemical properties of silicon-carbonic raw material – rice-husk, thermophysical characteristics of the process of rice-husk pyrolysis in nonreactive and oxidizing environment; structure and phase composition of products of the rice-husk pyrolysis in interval of temperatures 150 – 850 °С and high temperature pyrolysis in interval of temperatures 900 – 1 500 °С. There are defined the silicon-carbon production conditions, which meet the requirements applicable to charging materials at production of technical silicon and silicon carbide.

Photovoltaic characteristics of porous silicon /(n+ - p) silicon solar cells

International Nuclear Information System (INIS)

Dzhafarov, T.D.; Aslanov, S.S.; Ragimov, S.H.; Sadigov, M.S.; Nabiyeva, A.F.; Yuksel, Aydin S.

2012-01-01

Full text : The purpose of this work is to improve the photovoltaic parameters of the screen-printed silicon solar cells by formation the nano-porous silicon film on the frontal surface of the cell. The photovoltaic characteristics of two type silicon solar cells with and without porous silicon layer were measured and compared. A remarkable increment of short-circuit current density and the efficiency by 48 percent and 20 percent, respectively, have been achieved for PS/(n + - pSi) solar cell comparing to (n + - p)Si solar cell without PS layer

TXRF analysis of trace metals in thin silicon nitride films

International Nuclear Information System (INIS)

Vereecke, G.; Arnauts, S.; Verstraeten, K.; Schaekers, M.; Heyrts, M.M.

2000-01-01

As critical dimensions of integrated circuits continue to decrease, high dielectric constant materials such as silicon nitride are being considered to replace silicon dioxide in capacitors and transistors. The achievement of low levels of metal contamination in these layers is critical for high performance and reliability. Existing methods of quantitative analysis of trace metals in silicon nitride require high amounts of sample (from about 0.1 to 1 g, compared to a mass of 0.2 mg for a 2 nm thick film on a 8'' silicon wafer), and involve digestion steps not applicable to films on wafers or non-standard techniques such as neutron activation analysis. A novel approach has recently been developed to analyze trace metals in thin films with analytical techniques currently used in the semiconductor industry. Sample preparation consists of three steps: (1) decomposition of the silicon nitride matrix by moist HF condensed at the wafer surface to form ammonium fluosilicate. (2) vaporization of the fluosilicate by a short heat treatment at 300 o C. (3) collection of contaminants by scanning the wafer surface with a solution droplet (VPD-DSC procedure). The determination of trace metals is performed by drying the droplet on the wafer and by analyzing the residue by TXRF, as it offers the advantages of multi-elemental analysis with no dilution of the sample. The lower limits of detection for metals in 2 nm thick films on 8'' silicon wafers range from about 10 to 200 ng/g. The present study will focus on the matrix effects and the possible loss of analyte associated with the evaporation of the fluosilicate salt, in relation with the accuracy and the reproducibility of the method. The benefits of using an internal standard will be assessed. Results will be presented from both model samples (ammonium fluoride contaminated with metallic salts) and real samples (silicon nitride films from a production tool). (author)

Diatom-induced silicon isotopic fractionation in Antarctic sea ice

Science.gov (United States)

Francois, F.; Damien, C.; Jean-Louis, T.; Anthony, W.; Luc, A.

2006-12-01

We measured silicon-isotopic composition of dissolved silicon and biogenic silica collected by sequential melting from spring 2003 Antarctic pack ice (Australian sector). Sea ice is a key ecosystem in the Southern Ocean and its melting in spring has been often thought to have a seeding effect for the surface waters, triggering blooms in the mixed layer. This work is the first investigation of the silicon isotopes' proxy in sea ice and allows to estimate the activity of sea-ice diatoms in the different brine structures and the influence of sea- ice diatoms on the spring ice edge blooms. The relative use of the dissolved silicon pool by sea-ice diatoms is usually assessed by calculating nutrient:salinity ratios in the brines. However such an approach is biased by difficulties in evaluating the initial nutrient concentrations in the different brines structures, and by the impossibility to account for late sporadic nutrient replenishments. The silicon-isotopic composition of biogenic silica is a convenient alternative since it integrates an average Si utilization on all generations of diatoms. Measurements were performed on a MC-ICP-MS, in dry plasma mode using external Mg doping. Results are expressed as delta29Si relative to the NBS28 standard. From three sea ice cores with contrasted physico-chemical characteristics, we report significant isotopic fractionations linked to the diatoms activity, with distinct silicon biogeochemical dynamics between different brine structure. The diatoms in snow ice and in brine pockets of frazil or congelation ice have the most positive silicon-isotopic composition (+0.53 to +0.86 p.mil), indicating that they grow in a closed system and use a significant part of the small dissolved silicon pool. In the brine channels and skeletal layer, diatoms display a relatively less positive Si-isotopic composition (+0.41 to +0.70 p.mil), although it is still heavier compared to equilibrium fractionation (+0.38 p.mil). This suggests that they have

Performance improvement of silicon solar cells by nanoporous silicon coating

Directory of Open Access Journals (Sweden)

Dzhafarov T. D.

2012-04-01

Full Text Available In the present paper the method is shown to improve the photovoltaic parameters of screen-printed silicon solar cells by nanoporous silicon film formation on the frontal surface of the cell using the electrochemical etching. The possible mechanisms responsible for observed improvement of silicon solar cell performance are discussed.

Reprogramming hMSCs morphology with silicon/porous silicon geometric micro-patterns.

Science.gov (United States)

Ynsa, M D; Dang, Z Y; Manso-Silvan, M; Song, J; Azimi, S; Wu, J F; Liang, H D; Torres-Costa, V; Punzon-Quijorna, E; Breese, M B H; Garcia-Ruiz, J P

2014-04-01

Geometric micro-patterned surfaces of silicon combined with porous silicon (Si/PSi) have been manufactured to study the behaviour of human Mesenchymal Stem Cells (hMSCs). These micro-patterns consist of regular silicon hexagons surrounded by spaced columns of silicon equilateral triangles separated by PSi. The results show that, at an early culture stage, the hMSCs resemble quiescent cells on the central hexagons with centered nuclei and actin/β-catenin and a microtubules network denoting cell adhesion. After 2 days, hMSCs adapted their morphology and cytoskeleton proteins from cell-cell dominant interactions at the center of the hexagonal surface. This was followed by an intermediate zone with some external actin fibres/β-catenin interactions and an outer zone where the dominant interactions are cell-silicon. Cells move into silicon columns to divide, migrate and communicate. Furthermore, results show that Runx2 and vitamin D receptors, both specific transcription factors for skeleton-derived cells, are expressed in cells grown on micropatterned silicon under all observed circumstances. On the other hand, non-phenotypic alterations are under cell growth and migration on Si/PSi substrates. The former consideration strongly supports the use of micro-patterned silicon surfaces to address pending questions about the mechanisms of human bone biogenesis/pathogenesis and the study of bone scaffolds.

Study on structural properties of epitaxial silicon films on annealed double layer porous silicon

International Nuclear Information System (INIS)

Yue Zhihao; Shen Honglie; Cai Hong; Lv Hongjie; Liu Bin

2012-01-01

In this paper, epitaxial silicon films were grown on annealed double layer porous silicon by LPCVD. The evolvement of the double layer porous silicon before and after thermal annealing was investigated by scanning electron microscope. X-ray diffraction and Raman spectroscopy were used to investigate the structural properties of the epitaxial silicon thin films grown at different temperature and different pressure. The results show that the surface of the low-porosity layer becomes smooth and there are just few silicon-bridges connecting the porous layer and the substrate wafer. The qualities of the epitaxial silicon thin films become better along with increasing deposition temperature. All of the Raman peaks of silicon films with different deposition pressure are situated at 521 cm -1 under the deposition temperature of 1100 °C, and the Raman intensity of the silicon film deposited at 100 Pa is much closer to that of the monocrystalline silicon wafer. The epitaxial silicon films are all (4 0 0)-oriented and (4 0 0) peak of silicon film deposited at 100 Pa is more symmetric.

Magnesium Oxide (MgO) pH-sensitive Sensing Membrane in Electrolyte-Insulator-Semiconductor Structures with CF4 Plasma Treatment.

Science.gov (United States)

Kao, Chyuan-Haur; Chang, Chia Lung; Su, Wei Ming; Chen, Yu Tzu; Lu, Chien Cheng; Lee, Yu Shan; Hong, Chen Hao; Lin, Chan-Yu; Chen, Hsiang

2017-08-03

Magnesium oxide (MgO) sensing membranes in pH-sensitive electrolyte-insulator-semiconductor structures were fabricated on silicon substrate. To optimize the sensing capability of the membrane, CF 4 plasma was incorporated to improve the material quality of MgO films. Multiple material analyses including FESEM, XRD, AFM, and SIMS indicate that plasma treatment might enhance the crystallization and increase the grain size. Therefore, the sensing behaviors in terms of sensitivity, linearity, hysteresis effects, and drift rates might be improved. MgO-based EIS membranes with CF 4 plasma treatment show promise for future industrial biosensing applications.

Regenerable, innovative porous silicon-based polymer-derived ceramics for removal of methylene blue and rhodamine B from textile and environmental waters.

Science.gov (United States)

Bruzzoniti, Maria Concetta; Appendini, Marta; Onida, Barbara; Castiglioni, Michele; Del Bubba, Massimo; Vanzetti, Lia; Jana, Prasanta; Sorarù, Gian Domenico; Rivoira, Luca

2018-04-01

The presence of residual color in treated textile wastewater above the regulation limits is still a critical issue in many textile districts. Innovative, polymer-derived ceramics of the Si-C-O system were here synthesized in order to obtain porous nanocomposite materials where a free carbon phase is dispersed into a silicon carbide/silicon oxycarbide network. The sorbents were comprehensively characterized for the removal of two model water-soluble dyes (i.e., the cation methylene blue and the zwitterion rhodamine B). Adsorption is very rapid and controlled by intra-particle and/or film diffusion, depending on dye concentration. Among the nanocomposites studied, the SiOC aerogel (total capacity about 45 mg/g, is easily regenerated under mild treatment (250 °C, 2 h). Adsorption of dyes is not affected by the matrix composition: removals of 150 mg/L methylene blue from river water and simulated textile wastewater with high content of metal ions (2-50 mg/L) and chemical oxygen demand (800 mg/L) were higher than 92% and quantitative for a dye concentration of 1 mg/L.

TEM microstructural characterization of melt-spun aged Al-6Si-3Cu-xMg alloys

International Nuclear Information System (INIS)

Lopez, Ismeli Alfonso; Zepeda, Cuauhtemoc Maldonado; Gonzalez Reyes, Jose Gonzalo; Flores, Ariosto Medina; Rodriguez, Juan Serrato; Gomez, Luis Bejar

2007-01-01

Three Al-6Si-3Cu-xMg alloys (x = 0.59, 3.80 and 6.78 wt.%) were produced using melt-spinning. As-melt-spun ribbons were aged at 150, 180 and 210 deg. C for times between 0.05 and 100 h. Microstructural changes were examined using transmission electron microscopy (TEM) and microhardness was measured. TEM analysis of the as-melt-spun alloys revealed 5 nm nanoparticles and larger particles (50 nm) composed of Al 2 Cu (θ) for the 0.59% Mg alloy and Al 5 Cu 2 Mg 8 Si 6 (Q) for 3.80% and 6.78% Mg alloys. Silicon solid solubility was extended to 9.0 at.% and Mg in solid solution reached 6.7 at.%. After aging treatments the 6.78% Mg alloy exhibited the most significant increase in microhardness, reaching 260 kg/mm 2 . TEM analysis of aged specimens also showed θ and Q phase (5-20 nm nanoparticles and 35-40 nm particles). The combination of the volume fraction and size of the particles plays an important role in microhardness variation

Light emitting structures porous silicon-silicon substrate

International Nuclear Information System (INIS)

Monastyrskii, L.S.; Olenych, I.B.; Panasjuk, M.R.; Savchyn, V.P.

1999-01-01

The research of spectroscopic properties of porous silicon has been done. Complex of photoluminescence, electroluminescence, cathodoluminescence, thermostimulated depolarisation current analyte methods have been applied to study of geterostructures and free layers of porous silicon. Light emitting processes had tendency to decrease. The character of decay for all kinds of luminescence were different

Investigation of blue luminescence in Mg doped AlN films

Energy Technology Data Exchange (ETDEWEB)

Sun, Xiliang; Xiong, Juan, E-mail: xiongjuana@163.com; Zhang, Weihai; Liu, Lei; Gu, Haoshuang, E-mail: guhsh@hubu.edu.cn

2015-02-05

Highlights: • AlN films doped with 0.8–4.4 at.% Mg were deposited by magnetron sputtering. • Structural and photoluminescence properties of Mg-doped AlN films were synthesized in detailed. • A broad blue band centered at 420 nm and 440 nm was observed in Mg-doped AlN films. • An enhancement of A1 (TO) mod and a slightly blue-shift of E2 (high) mode were observed. - Abstract: The Al{sub 1−x}Mg{sub x}N thin films were deposited on (1 0 0) silicon substrates by magnetron sputtering. The structural and photoluminescence properties of the films with varying Mg concentrations were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and photoluminescence (PL), respectively. The results clearly showed that the Mg atoms successfully incorporated into AlN, while the crystal structure of the films was maintained. The Raman spectra of Al{sub 1−x}Mg{sub x}N films reveals the enhancement of A{sub 1} (TO) mode, a slightly blue-shift and an augment in FWHM for E{sub 2} (high) phonon mode with increasing Mg content, which can be associated with the deterioration of (0 0 2) orientation and the appearance of (1 0 0) orientation. A broad blue band centered at 420 nm and 440 nm was observed in Mg-doped AlN films. It was suggested that the transitions from the shallow donor level not only to the ground state but also to the excited states of the deep level was responsible for the broad blue emission band. This work indicates the AlN film for the application in lighting emission devices.

Gelcasting of SiC/Si for preparation of silicon nitride bonded silicon carbide

International Nuclear Information System (INIS)

Xie, Z.P.; Tsinghua University, Beijing,; Cheng, Y.B.; Lu, J.W.; Huang, Y.

2000-01-01

In the present paper, gelcasting of aqueous slurry with coarse silicon carbide(1mm) and fine silicon particles was investigated to fabricate silicon nitride bonded silicon carbide materials. Through the examination of influence of different polyelectrolytes on the Zeta potential and viscosity of silicon and silicon carbide suspensions, a stable SiC/Si suspension with 60 vol% solid loading could be prepared by using polyelectrolyte of D3005 and sodium alginate. Gelation of this suspension can complete in 10-30 min at 60-80 deg C after cast into mold. After demolded, the wet green body can be dried directly in furnace and the green strength will develop during drying. Complex shape parts with near net size were prepared by the process. Effects of the debindering process on nitridation and density of silicon nitride bonded silicon carbide were also examined. Copyright (2000) The Australian Ceramic Society

Multifunctional Graphene-Silicone Elastomer Nanocomposite, Method of Making the Same, and Uses Thereof

Science.gov (United States)

Pan, Shuyang (Inventor); Aksay, Ilhan A. (Inventor); Prud'Homme, Robert K. (Inventor)

2018-01-01

A nanocomposite composition having a silicone elastomer matrix having therein a filler loading of greater than 0.05 wt %, based on total nanocomposite weight, wherein the filler is functional graphene sheets (FGS) having a surface area of from 300 sq m/g to 2630 sq m2/g; and a method for producing the nanocomposite and uses thereof.

Silicon detectors

International Nuclear Information System (INIS)

Klanner, R.

1984-08-01

The status and recent progress of silicon detectors for high energy physics is reviewed. Emphasis is put on detectors with high spatial resolution and the use of silicon detectors in calorimeters. (orig.)

FTIR studies of swift silicon and oxygen ion irradiated porous silicon

International Nuclear Information System (INIS)

Bhave, Tejashree M.; Hullavarad, S.S.; Bhoraskar, S.V.; Hegde, S.G.; Kanjilal, D.

1999-01-01

Fourier Transform Infrared Spectroscopy has been used to study the bond restructuring in silicon and oxygen irradiated porous silicon. Boron doped p-type (1 1 1) porous silicon was irradiated with 10 MeV silicon and a 14 MeV oxygen ions at different doses ranging between 10 12 and 10 14 ions cm -2 . The yield of PL in porous silicon irradiated samples was observed to increase considerably while in oxygen irradiated samples it was seen to improve only by a small extent for lower doses whereas it decreased for higher doses. The results were interpreted in view of the relative intensities of the absorption peaks associated with O-Si-H and Si-H stretch bonds

On the way to enhance the optical absorption of a-Si in NIR by embedding Mg{sub 2}Si thin film

Energy Technology Data Exchange (ETDEWEB)

Chernev, I. M., E-mail: igor-chernev7@mail.ru; Shevlyagin, A. V.; Galkin, K. N. [Institute of Automation and Control Processes of FEB RAS, Radio St. 5, 690041 Vladivostok (Russian Federation); Stuchlik, J. [Institute of Physics of the ASCR, v. v. i., Cukrovarnická 10/112, 162 00 Praha 6 (Czech Republic); Remes, Z. [Institute of Physics of the ASCR, v. v. i., Cukrovarnická 10/112, 162 00 Praha 6 (Czech Republic); FBE CTU, Nam. Sitna 3105, 272 01 Kladno (Czech Republic); Fajgar, R. [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojová 135, 165 02 Praha 6 (Czech Republic); Galkin, N. G. [Institute of Automation and Control Processes of FEB RAS, Radio St. 5, 690041 Vladivostok (Russian Federation); Far Eastern Federal University, School of Natural Sciences, Sukhanova St. 8, 690950 Vladivostok (Russian Federation)

2016-07-25

Mg{sub 2}Si thin film was embedded in amorphous silicon matrix by solid phase epitaxy. The structure and optical properties were investigated by electron energy loss, X-ray photoelectron, Raman, and photo thermal deflection spectroscopy measurements. It was found that in the photon energy range of 0.8–1.7 eV, the light absorption of the structure with magnesium silicide (Mg{sub 2}Si) film embedded in a-Si(i) matrix is 1.5 times higher than that for the same structure without Mg{sub 2}Si.

Annealing temperature dependence of photoluminescent characteristics of silicon nanocrystals embedded in silicon-rich silicon nitride films grown by PECVD

International Nuclear Information System (INIS)

Chao, D.S.; Liang, J.H.

2013-01-01

Recently, light emission from silicon nanostructures has gained great interest due to its promising potential of realizing silicon-based optoelectronic applications. In this study, luminescent silicon nanocrystals (Si–NCs) were in situ synthesized in silicon-rich silicon nitride (SRSN) films grown by plasma-enhanced chemical vapor deposition (PECVD). SRSN films with various excess silicon contents were deposited by adjusting SiH 4 flow rate to 100 and 200 sccm and keeping NH 3 one at 40 sccm, and followed by furnace annealing (FA) treatments at 600, 850 and 1100 °C for 1 h. The effects of excess silicon content and post-annealing temperature on optical properties of Si–NCs were investigated by photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). The origins of two groups of PL peaks found in this study can be attributed to defect-related interface states and quantum confinement effects (QCE). Defect-related interface states lead to the photon energy levels almost kept constant at about 3.4 eV, while QCE results in visible and tunable PL emission in the spectral range of yellow and blue light which depends on excess silicon content and post-annealing temperature. In addition, PL intensity was also demonstrated to be highly correlative to the excess silicon content and post-annealing temperature due to its corresponding effects on size, density, crystallinity, and surface passivation of Si–NCs. Considering the trade-off between surface passivation and structural properties of Si–NCs, an optimal post-annealing temperature of 600 °C was suggested to maximize the PL intensity of the SRSN films

Strategies for doped nanocrystalline silicon integration in silicon heterojunction solar cells

Czech Academy of Sciences Publication Activity Database

Seif, J.; Descoeudres, A.; Nogay, G.; Hänni, S.; de Nicolas, S.M.; Holm, N.; Geissbühler, J.; Hessler-Wyser, A.; Duchamp, M.; Dunin-Borkowski, R.E.; Ledinský, Martin; De Wolf, S.; Ballif, C.

2016-01-01

Roč. 6, č. 5 (2016), s. 1132-1140 ISSN 2156-3381 R&D Projects: GA MŠk LM2015087 Institutional support: RVO:68378271 Keywords : microcrystalline silicon * nanocrystalline silicon * silicon heterojunctions (SHJs) * solar cells Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.712, year: 2016

Microstructure and wear behavior of friction stir processed cast hypereutectic aluminum silicon

Directory of Open Access Journals (Sweden)

Ahmad Rosli

2017-01-01

Full Text Available Hypereutectic as-cast Al-18Si-Cu-Ni alloy was subjected to friction stir processing (FSP. The resultant effect of FSP on the alloy was evaluated by microstructure analysis and wear tests (dry sliding. A significant microstructural modification and enhancement in wear behavior of Al-18Si-Cu-Ni alloy was recorded after friction stir processing. Wear resistance improvement was related to considerable modification in size, morphology and distribution of silicon particles, and hardness improvement. It was found that lower tool rotation speed was more effective to refine silicon particles and in turn increase wear resistance. Minimum Si particle mean area of about 47.8 µm2, and wear rate of 0.0155 mg/m was achieved.

Periodically poled silicon

Science.gov (United States)

Hon, Nick K.; Tsia, Kevin K.; Solli, Daniel R.; Khurgin, Jacob B.; Jalali, Bahram

2010-02-01

Bulk centrosymmetric silicon lacks second-order optical nonlinearity χ(2) - a foundational component of nonlinear optics. Here, we propose a new class of photonic device which enables χ(2) as well as quasi-phase matching based on periodic stress fields in silicon - periodically-poled silicon (PePSi). This concept adds the periodic poling capability to silicon photonics, and allows the excellent crystal quality and advanced manufacturing capabilities of silicon to be harnessed for devices based on χ(2)) effects. The concept can also be simply achieved by having periodic arrangement of stressed thin films along a silicon waveguide. As an example of the utility, we present simulations showing that mid-wave infrared radiation can be efficiently generated through difference frequency generation from near-infrared with a conversion efficiency of 50% based on χ(2) values measurements for strained silicon reported in the literature [Jacobson et al. Nature 441, 199 (2006)]. The use of PePSi for frequency conversion can also be extended to terahertz generation. With integrated piezoelectric material, dynamically control of χ(2)nonlinearity in PePSi waveguide may also be achieved. The successful realization of PePSi based devices depends on the strength of the stress induced χ(2) in silicon. Presently, there exists a significant discrepancy in the literature between the theoretical and experimentally measured values. We present a simple theoretical model that produces result consistent with prior theoretical works and use this model to identify possible reasons for this discrepancy.

Efficiency Enhancement of Silicon Solar Cells by Porous Silicon Technology

Directory of Open Access Journals (Sweden)

Eugenijus SHATKOVSKIS

2012-09-01

Full Text Available Silicon solar cells produced by a usual technology in p-type, crystalline silicon wafer were investigated. The manufactured solar cells were of total thickness 450 mm, the junction depth was of 0.5 mm – 0.7 mm. Porous silicon technologies were adapted to enhance cell efficiency. The production of porous silicon layer was carried out in HF: ethanol = 1 : 2 volume ratio electrolytes, illuminating by 50 W halogen lamps at the time of processing. The etching current was computer-controlled in the limits of (6 ÷ 14 mA/cm2, etching time was set in the interval of (10 ÷ 20 s. The characteristics and performance of the solar cells samples was carried out illuminating by Xenon 5000 K lamp light. Current-voltage characteristic studies have shown that porous silicon structures produced affect the extent of dark and lighting parameters of the samples. Exactly it affects current-voltage characteristic and serial resistance of the cells. It has shown, the formation of porous silicon structure causes an increase in the electric power created of solar cell. Conversion efficiency increases also respectively to the initial efficiency of cell. Increase of solar cell maximum power in 15 or even more percent is found. The highest increase in power have been observed in the spectral range of Dl @ (450 ÷ 850 nm, where ~ 60 % of the A1.5 spectra solar energy is located. It has been demonstrated that porous silicon technology is effective tool to improve the silicon solar cells performance.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2428

Chiral silicon nanostructures

International Nuclear Information System (INIS)

Schubert, E.; Fahlteich, J.; Hoeche, Th.; Wagner, G.; Rauschenbach, B.

2006-01-01

Glancing angle ion beam assisted deposition is used for the growth of amorphous silicon nanospirals onto [0 0 1] silicon substrates in a temperature range from room temperature to 475 deg. C. The nanostructures are post-growth annealed in an argon atmosphere at various temperatures ranging from 400 deg. C to 800 deg. C. Recrystallization of silicon within the persisting nanospiral configuration is demonstrated for annealing temperatures above 800 deg. C. Transmission electron microscopy and Raman spectroscopy are used to characterize the silicon samples prior and after temperature treatment

The chemistry of silicon

CERN Document Server

Rochow, E G; Emeléus, H J; Nyholm, Ronald

1975-01-01

Pergamon Texts in Organic Chemistry, Volume 9: The Chemistry of Silicon presents information essential in understanding the chemical properties of silicon. The book first covers the fundamental aspects of silicon, such as its nuclear, physical, and chemical properties. The text also details the history of silicon, its occurrence and distribution, and applications. Next, the selection enumerates the compounds and complexes of silicon, along with organosilicon compounds. The text will be of great interest to chemists and chemical engineers. Other researchers working on research study involving s

The effect of carbon mole ratio on the fabrication of silicon carbide

Directory of Open Access Journals (Sweden)

Sutham Niyomwas

2008-03-01

Full Text Available Silicon Carbide (SiC particles were synthesized by self-propagating high temperature synthesis (SHS from a powder mixture of SiO2-C-Mg. The reaction was carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The effects of carbon mole ratio on the precursor mixture (C/SiO2/Mg: 1/1/2 to 3/1/2 and on the SiC conversion were investigated using X-ray diffraction and scanning electron microscope technique. The as-synthesized products of SiC-MgO powders were leached with 0.1M HCl acid solution to obtain the SiC particles.

Study on the graphene/silicon Schottky diodes by transferring graphene transparent electrodes on silicon

International Nuclear Information System (INIS)

Wang, Xiaojuan; Li, Dong; Zhang, Qichong; Zou, Liping; Wang, Fengli; Zhou, Jun; Zhang, Zengxing

2015-01-01

Graphene/silicon heterostructures present a Schottky characteristic and have potential applications for solar cells and photodetectors. Here, we fabricated graphene/silicon heterostructures by using chemical vapor deposition derived graphene and n-type silicon, and studied the electronic and optoelectronic properties through varying their interface and silicon resistivity. The results exhibit that the properties of the fabricated configurations can be effectively modulated. The graphene/silicon heterostructures with a Si (111) interface and high resistivity show a better photovoltaic behavior and should be applied for high-performance photodetectors. With the combined atomic force microscopy and theoretical analysis, the possible origination is discussed. The work here should be helpful on exploring high-performance graphene/silicon photoelectronics. - Highlights: • Different graphene/silicon heterostructures were fabricated. • Electronic and optoelectronic properties of the heterostructures were studied. • Graphene/silicon heterostructures were further explored for photodetectors.

Study on the graphene/silicon Schottky diodes by transferring graphene transparent electrodes on silicon

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaojuan [MOE Key Laboratory of Advanced Micro-structured Materials & Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Li, Dong; Zhang, Qichong; Zou, Liping; Wang, Fengli [MOE Key Laboratory of Advanced Micro-structured Materials & Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Zhou, Jun, E-mail: zhoujunzhou@tongji.edu.cn [Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Zhang, Zengxing, E-mail: zhangzx@tongji.edu.cn [MOE Key Laboratory of Advanced Micro-structured Materials & Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China)

2015-10-01

Graphene/silicon heterostructures present a Schottky characteristic and have potential applications for solar cells and photodetectors. Here, we fabricated graphene/silicon heterostructures by using chemical vapor deposition derived graphene and n-type silicon, and studied the electronic and optoelectronic properties through varying their interface and silicon resistivity. The results exhibit that the properties of the fabricated configurations can be effectively modulated. The graphene/silicon heterostructures with a Si (111) interface and high resistivity show a better photovoltaic behavior and should be applied for high-performance photodetectors. With the combined atomic force microscopy and theoretical analysis, the possible origination is discussed. The work here should be helpful on exploring high-performance graphene/silicon photoelectronics. - Highlights: • Different graphene/silicon heterostructures were fabricated. • Electronic and optoelectronic properties of the heterostructures were studied. • Graphene/silicon heterostructures were further explored for photodetectors.

Porous silicon powder as an adsorbent of heavy metal (nickel)

Science.gov (United States)

Nabil, Marwa; Motaweh, Hussien A.

2018-04-01

New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using sonication technique and was subsequently investigated as an adsorbent in batch systems for the adsorption Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the NPS powder were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Ni(II) reached 2665.33 mg/g and 82.6%, respectively, at an initial Ni(II) concentration of 100 mg/L, adsorption time of 30 min and no effect of the solution pH and adsorption temperature.

Irradiation effects of swift heavy ions on gallium arsenide, silicon and silicon diodes

International Nuclear Information System (INIS)

Bhoraskar, V.N.

2001-01-01

The irradiation effects of high energy lithium, boron, oxygen and silicon ions on crystalline silicon, gallium arsenide, porous silicon and silicon diodes were investigated. The ion energy and fluence were varied over the ranges 30 to 100 MeV and 10 11 to 10 14 ions/cm 2 respectively. Semiconductor samples were characterized with the x-ray fluorescence, photoluminescence, thermally stimulated exo-electron emission and optical reflectivity techniques. The life-time of minority carriers in crystalline silicon was measured with a pulsed electron beam and the lithium depth distribution in GaAs was measured with the neutron depth profiling technique. The diodes were characterized through electrical measurements. The results of optical reflectivity, life-time of minority carriers and photoluminescence show that swift heavy ions induce defects in the surface region of crystalline silicon. In the ion-irradiated GaAs, migration of silicon, oxygen and lithium atoms from the buried region towards the surface was observed, with orders of magnitude enhancement in the diffusion coefficients. Enhancement in the photoluminescence intensity was observed in the GaAs and porous silicon samples that, were irradiated with silicon ions. The trade-off between the turn-off time and the voltage, drop in diodes irradiated with different swift heavy ions was also studied. (author)

Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report

Energy Technology Data Exchange (ETDEWEB)

Sundberg, G.J.; Vartabedian, A.M.; Wade, J.A.; White, C.S. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.

1994-10-01

The purpose of joining, Phase 2 was to develop joining technologies for HIP`ed Si{sub 3}N{sub 4} with 4wt% Y{sub 2}O{sub 3} (NCX-5101) and for a siliconized SiC (NT230) for various geometries including: butt joins, curved joins and shaft to disk joins. In addition, more extensive mechanical characterization of silicon nitride joins to enhance the predictive capabilities of the analytical/numerical models for structural components in advanced heat engines was provided. Mechanical evaluation were performed by: flexure strength at 22 C and 1,370 C, stress rupture at 1,370 C, high temperature creep, 22 C tensile testing and spin tests. While the silicon nitride joins were produced with sufficient integrity for many applications, the lower join strength would limit its use in the more severe structural applications. Thus, the silicon carbide join quality was deemed unsatisfactory to advance to more complex, curved geometries. The silicon carbide joining methods covered within this contract, although not entirely successful, have emphasized the need to focus future efforts upon ways to obtain a homogeneous, well sintered parent/join interface prior to siliconization. In conclusion, the improved definition of the silicon carbide joining problem obtained by efforts during this contract have provided avenues for future work that could successfully obtain heat engine quality joins.

Hydrogen in amorphous silicon

International Nuclear Information System (INIS)

Peercy, P.S.

1980-01-01

The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH 1 ) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon

A convenient way of manufacturing silicon nanotubes on a silicon substrate

Energy Technology Data Exchange (ETDEWEB)

Zhang, Changchang; Cheng, Heming; Liu, Xiang, E-mail: liuxiang@ahut.edu.cn

2016-07-01

A convenient approach of preparing silicon nanotubes (SiNTs) on a silicon substrate is described in this work in detail. Firstly, a porous silicon (PSi) slice is prepared by a galvanic displacement reaction. Then it is put into aqueous solutions of 20% (w%) ammonium fluoride and 2.5 mM cobalt nitrate for a predetermined time. The cobalt ions are reduced and the resulted cobalt particles are deposited on the PSi slice. After the cobalt particles are removed with 5 M nitric acid a plenty of SiNTs come out and exhibit disorderly on the silicon substrate, which are illustrated by scanning electron microscopy (SEM). The compositions of the SiNTs are examined by energy-dispersive X-ray spectroscopy. Based on the SEM images, a suggested mechanism is put forward to explain the generation of the SiNTs on the PSi substrate. - Highlights: • A facile approach of preparing silicon nano tubes was invented. • The experimental results demonstrated the strong reducibility of Si-H{sub x} species. • It provided a new way of manufacturing silicon-contained hybrids.

Development of Radiation Hard Radiation Detectors, Differences between Czochralski Silicon and Float Zone Silicon

CERN Document Server

Tuominen, Eija

2012-01-01

The purpose of this work was to develop radiation hard silicon detectors. Radiation detectors made ofsilicon are cost effective and have excellent position resolution. Therefore, they are widely used fortrack finding and particle analysis in large high-energy physics experiments. Silicon detectors willalso be used in the CMS (Compact Muon Solenoid) experiment that is being built at the LHC (LargeHadron Collider) accelerator at CERN (European Organisation for Nuclear Research). This work wasdone in the CMS programme of Helsinki Institute of Physics (HIP).Exposure of the silicon material to particle radiation causes irreversible defects that deteriorate theperformance of the silicon detectors. In HIP CMS Programme, our approach was to improve theradiation hardness of the silicon material with increased oxygen concentration in silicon material. Westudied two different methods: diffusion oxygenation of Float Zone silicon and use of high resistivityCzochralski silicon.We processed, characterised, tested in a parti...

Crystallisation and microstructure of low-silicon silumins with alloy additions

Directory of Open Access Journals (Sweden)

S. Pietrowski

2011-07-01

Full Text Available The paper presents the results of the analysis of crystallisation and microstructure of non-alloy silumins that contain: 2,0÷6,0% of Si and alloy additions, approximately: 4,0% Ni, 4,0% of Cu and 0,5% of Mg, the knowledge of which is still very little. It has been proven that in non-alloy silumins, the increase of silicone concentration causes extending of crystallisation time of the eutectic mixture α+and refinement of α phase dendrites. It also causes the increase of the temperature of crystallisation of the eutectic mixture α+ . Alloy additions: Ni, Cu and Mg decrease by approximately 30 C the liquidus and solidus temperatures of silumins and extend the time of their crystallisation by around 100 sec. in comparison with non-alloy silumins. It is caused by crystallisation of additional phases Al3NiCu, Mg2Si and Al2Cu. Nickel, copper and magnesium refine the microstructure of castings.

NMR investigation of boron impurities in refined metallurgical grade silicon

Energy Technology Data Exchange (ETDEWEB)

Grafe, Hans-Joachim; Loeser, Wolfgang; Schmitz, Steffen; Sakaliyska, Miroslava [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Wurmehl, Sabine [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Institute for Solid State Physics, Technische Universitaet Dresden (Germany); Eisert, Stefan; Reichenbach, Birk; Mueller, Tim [Adensis GmbH, Dresden (Germany); Acker, Joerg; Rietig, Anja; Ducke, Jana [Department of Chemistry, Faculty for Natural Sciences, Brandenburg Technical University Cottbus-Senftenberg, Senftenberg (Germany)

2015-09-15

The nuclear magnetic resonance (NMR) method was applied for tracking boron impurities in the refining process of metallurgical grade (MG) silicon. From the NMR signal of the {sup 11}B isotope at an operating temperature 4.2 K, the boron concentration can be estimated down to the order of 1-10 wppm B. After melting and resolidification of MG-Si alloyed with Ca and Ti, a major fraction of B impurities remains in the Si solid solution as inferred from the characteristic NMR frequency. The alloying element Ti does not form substantial fractions of TiB{sub 2}. Acid leaching of crushed powders of MG-Si alloyed with Ca and Ti can diminish the initial impurity content of B suggesting its accumulation in the grain boundary phases. NMR signals of TiB{sub 2} at 4.2 K and room temperature (RT), and of poly-Si with different B doping at 4.2 K. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

CHARACTERIZATION OF THE ELECTROPHYSICAL PROPERTIES OF SILICON-SILICON DIOXIDE INTERFACE USING PROBE ELECTROMETRY METHODS

Directory of Open Access Journals (Sweden)

V. А. Pilipenko

2017-01-01

Full Text Available Introduction of submicron design standards into microelectronic industry and a decrease of the gate dielectric thickness raise the importance of the analysis of microinhomogeneities in the silicon-silicon dioxide system. However, there is very little to no information on practical implementation of probe electrometry methods, and particularly scanning Kelvin probe method, in the interoperational control of real semiconductor manufacturing process. The purpose of the study was the development of methods for nondestructive testing of semiconductor wafers based on the determination of electrophysical properties of the silicon-silicon dioxide interface and their spatial distribution over wafer’s surface using non-contact probe electrometry methods.Traditional C-V curve analysis and scanning Kelvin probe method were used to characterize silicon- silicon dioxide interface. The samples under testing were silicon wafers of KEF 4.5 and KDB 12 type (orientation <100>, diameter 100 mm.Probe electrometry results revealed uniform spatial distribution of wafer’s surface potential after its preliminary rapid thermal treatment. Silicon-silicon dioxide electric potential values were also higher after treatment than before it. This potential growth correlates with the drop in interface charge density. At the same time local changes in surface potential indicate changes in surface layer structure.Probe electrometry results qualitatively reflect changes of interface charge density in silicon-silicon dioxide structure during its technological treatment. Inhomogeneities of surface potential distribution reflect inhomogeneity of damaged layer thickness and can be used as a means for localization of interface treatment defects.

Silicon microphotonic waveguides

International Nuclear Information System (INIS)

Ta'eed, V.; Steel, M.J.; Grillet, C.; Eggleton, B.; Du, J.; Glasscock, J.; Savvides, N.

2004-01-01

Full text: Silicon microphotonic devices have been drawing increasing attention in the past few years. The high index-difference between silicon and its oxide (Δn = 2) suggests a potential for high-density integration of optical functions on to a photonic chip. Additionally, it has been shown that silicon exhibits strong Raman nonlinearity, a necessary property as light interaction can occur only by means of nonlinearities in the propagation medium. The small dimensions of silicon waveguides require the design of efficient tapers to couple light to them. We have used the beam propagation method (RSoft BeamPROP) to understand the principles and design of an inverse-taper mode-converter as implemented in several recent papers. We report on progress in the design and fabrication of silicon-based waveguides. Preliminary work has been conducted by patterning silicon-on-insulator (SOI) wafers using optical lithography and reactive ion etching. Thus far, only rib waveguides have been designed, as single-mode ridge-waveguides are beyond the capabilities of conventional optical lithography. We have recently moved to electron beam lithography as the higher resolutions permitted will provide the flexibility to begin fabricating sub-micron waveguides

Performance Analysis of a Grid-Connected Upgraded Metallurgical Grade Silicon Photovoltaic System

Directory of Open Access Journals (Sweden)

Chao Huang

2016-05-01

Full Text Available Because of their low cost, photovoltaic (PV cells made from upgraded metallurgical grade silicon (UMG-Si are a promising alternative to conventional solar grade silicon-based PV cells. This study investigates the outdoor performance of a 1.26 kW grid-connected UMG-Si PV system over five years, reporting the energy yields and performance ratio and estimating the long-term performance degradation rate. To make this investigation more meaningful, the performance of a mono-Si PV system installed at the same place and studied during the same period of time is presented for reference. Furthermore, this study systematizes and rationalizes the necessity of a data selection and filtering process to improve the accuracy of degradation rate estimation. The impact of plane-of-array irradiation threshold for data filtering on performance ratio and degradation rate is also studied. The UMG-Si PV system’s monthly performance ratio after data filtering ranged from 84% to 93% over the observation period. The annual degradation rate was 0.44% derived from time series of monthly performance ratio using the classical decomposition method. A comparison of performance ratio and degradation rate to conventional crystalline silicon-based PV systems suggests that performance of the UMG-Si PV system is comparable to that of conventional systems.

Ceramic silicon-boron-carbon fibers from organic silicon-boron-polymers

Science.gov (United States)

Riccitiello, Salvatore R. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

1993-01-01

Novel high strength ceramic fibers derived from boron, silicon, and carbon organic precursor polymers are discussed. The ceramic fibers are thermally stable up to and beyond 1200 C in air. The method of preparation of the boron-silicon-carbon fibers from a low oxygen content organosilicon boron precursor polymer of the general formula Si(R2)BR(sup 1) includes melt-spinning, crosslinking, and pyrolysis. Specifically, the crosslinked (or cured) precursor organic polymer fibers do not melt or deform during pyrolysis to form the silicon-boron-carbon ceramic fiber. These novel silicon-boron-carbon ceramic fibers are useful in high temperature applications because they retain tensile and other properties up to 1200 C, from 1200 to 1300 C, and in some cases higher than 1300 C.

Catastrophic degradation of the interface of epitaxial silicon carbide on silicon at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Pradeepkumar, Aiswarya; Mishra, Neeraj; Kermany, Atieh Ranjbar; Iacopi, Francesca [Queensland Micro and Nanotechnology Centre and Environmental Futures Research Institute, Griffith University, Nathan QLD 4111 (Australia); Boeckl, John J. [Materials and Manufacturing Directorate, Air Force Research Laboratories, Wright-Patterson Air Force Base, Ohio 45433 (United States); Hellerstedt, Jack; Fuhrer, Michael S. [Monash Centre for Atomically Thin Materials, Monash University, Monash, VIC 3800 (Australia)

2016-07-04

Epitaxial cubic silicon carbide on silicon is of high potential technological relevance for the integration of a wide range of applications and materials with silicon technologies, such as micro electro mechanical systems, wide-bandgap electronics, and graphene. The hetero-epitaxial system engenders mechanical stresses at least up to a GPa, pressures making it extremely challenging to maintain the integrity of the silicon carbide/silicon interface. In this work, we investigate the stability of said interface and we find that high temperature annealing leads to a loss of integrity. High–resolution transmission electron microscopy analysis shows a morphologically degraded SiC/Si interface, while mechanical stress measurements indicate considerable relaxation of the interfacial stress. From an electrical point of view, the diode behaviour of the initial p-Si/n-SiC junction is catastrophically lost due to considerable inter-diffusion of atoms and charges across the interface upon annealing. Temperature dependent transport measurements confirm a severe electrical shorting of the epitaxial silicon carbide to the underlying substrate, indicating vast predominance of the silicon carriers in lateral transport above 25 K. This finding has crucial consequences on the integration of epitaxial silicon carbide on silicon and its potential applications.

Evaluation of Effect of Silicon on NaCl Tolerance in Annual Medicago scutellata L.

Directory of Open Access Journals (Sweden)

M Azizi

2016-07-01

Full Text Available Introduction Salinity is one of the most important stress resulting depletion of vegetation in large areas of the world including some regions of Iran. Reduction of plant growth due to salinity occurs with a range of mechanisms, including low external water potential, ion toxicity and interfere with the uptake. Silicon (Si is the second most abundant element in soil and could efficiently mitigate the effects of various biotic and abiotic stresses, such as drought, heavy metal toxicity and salinity on plants. Medicago scutellata is an important leguminous forage crop throughout the world that could increase soil nitrogen content via reduction of atmospheric nitrogen. To our knowledge, no study have examined the interaction of salinity and Si nutrition in Medicago scutellata or how the beneficial effects of Si in salt-stressed M. scutellata plants (if any are exerted. Accordingly, the aim of the present study was to evaluate the effect of silicon nutrition on salt tolerance of Medicago scutellata. Materials and Methods Seeds of alfalfa (Medicago scutellata L. were sterilized with a 2.5% sodium hypochlorite solution and were incubated in a moistened paper towel. Then, they germinated in the dark at 255  C for 48 h. Healthy seedlings of uniform sizes were selected for hydroponic culture (Hoagland solution in a 10×15×15 cm plastic pots. A factorial experiment carried out based on a completely randomized design with two factors. The first factor was salinity, including 0 and 100 mM NaCl and the second was silicon nutrition, including 0, 0.75 and 1.5 m.M sodium silicate. The pH of the nutrient solution was adjusted daily at 6.4  0.2 and nutrient solution was refreshed weekly. During the experiment, maximum and minimum air temperatures were 30ºC and 21ºC respectively, and the mean relative humidity was 67%. Four weeks after exerting the treatments, plants were harvested and used for the assessment of growth parameters and chemical analyses

Memory characteristics of silicon nitride with silicon nanocrystals as a charge trapping layer of nonvolatile memory devices

International Nuclear Information System (INIS)

Choi, Sangmoo; Yang, Hyundeok; Chang, Man; Baek, Sungkweon; Hwang, Hyunsang; Jeon, Sanghun; Kim, Juhyung; Kim, Chungwoo

2005-01-01

Silicon nitride with silicon nanocrystals formed by low-energy silicon plasma immersion ion implantation has been investigated as a charge trapping layer of a polycrystalline silicon-oxide-nitride-oxide-silicon-type nonvolatile memory device. Compared with the control sample without silicon nanocrystals, silicon nitride with silicon nanocrystals provides excellent memory characteristics, such as larger width of capacitance-voltage hysteresis, higher program/erase speed, and lower charge loss rate at elevated temperature. These improved memory characteristics are derived by incorporation of silicon nanocrystals into the charge trapping layer as additional accessible charge traps with a deeper effective trap energy level

Use of hydroxypropylmethylcellulose 2% for removing adherent silicone oil from silicone intraocular lenses

OpenAIRE

Wong , S Chien; Ramkissoon , Yashin D; Lopez , Mauricio; Page , Kristopher; Parkin , Ivan P; Sullivan , Paul M

2009-01-01

Abstract Background / aims: To investigate the effect of hydroxypropylmethylcellulose (HPMC) on the physical interaction (contact angle) between silicone oil and a silicone intraocular lens (IOL). Methods: In vitro experiments were performed, to determine the effect of HPMC (0.5%, 1% or 2%), with or without an additional simple mechanical manoeuvre, on the contact angle of silicone oil at the surface of both silicone and acrylic (control) IOLs. A balanced salt solu...

Single-Event Effects in Silicon and Silicon Carbide Power Devices

Science.gov (United States)

Lauenstein, Jean-Marie; Casey, Megan C.; LaBel, Kenneth A.; Topper, Alyson D.; Wilcox, Edward P.; Kim, Hak; Phan, Anthony M.

2014-01-01

NASA Electronics Parts and Packaging program-funded activities over the past year on single-event effects in silicon and silicon carbide power devices are presented, with focus on SiC device failure signatures.

Porous Silicon Nanowires

Science.gov (United States)

Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

2011-01-01

In this minreview, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures — single crystalline porous silicon nanowires. The growth of porous silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The porous silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion battery, gas sensor and drug delivery. PMID:21869999

Formation of multiple levels of porous silicon for buried insulators and conductors in silicon device technologies

Science.gov (United States)

Blewer, Robert S.; Gullinger, Terry R.; Kelly, Michael J.; Tsao, Sylvia S.

1991-01-01

A method of forming a multiple level porous silicon substrate for semiconductor integrated circuits including anodizing non-porous silicon layers of a multi-layer silicon substrate to form multiple levels of porous silicon. At least one porous silicon layer is then oxidized to form an insulating layer and at least one other layer of porous silicon beneath the insulating layer is metallized to form a buried conductive layer. Preferably the insulating layer and conductive layer are separated by an anodization barrier formed of non-porous silicon. By etching through the anodization barrier and subsequently forming a metallized conductive layer, a fully or partially insulated buried conductor may be fabricated under single crystal silicon.

Silicon: electrochemistry and luminescence

NARCIS (Netherlands)

Kooij, Ernst Stefan

1997-01-01

The electrochemistry of crystalline and porous silicon and the luminescence from porous silicon has been studied. One chapter deals with a model for the anodic dissolution of silicon in HF solution. In following chapters both the electrochemistry and various ways of generating visible

Polycrystalline Silicon Gettered by Porous Silicon and Heavy Phosphorous Diffusion

Institute of Scientific and Technical Information of China (English)

LIU Zuming(刘祖明); Souleymane K Traore; ZHANG Zhongwen(张忠文); LUO Yi(罗毅)

2004-01-01

The biggest barrier for photovoltaic (PV) utilization is its high cost, so the key for scale PV utilization is to further decrease the cost of solar cells. One way to improve the efficiency, and therefore lower the cost, is to increase the minority carrier lifetime by controlling the material defects. The main defects in grain boundaries of polycrystalline silicon gettered by porous silicon and heavy phosphorous diffusion have been studied. The porous silicon was formed on the two surfaces of wafers by chemical etching. Phosphorous was then diffused into the wafers at high temperature (900℃). After the porous silicon and diffusion layers were removed, the minority carrier lifetime was measured by photo-conductor decay. The results show that the lifetime's minority carriers are increased greatly after such treatment.

Autoimmune Syndrome Induced by Adjuvants (ASIA after Silicone Breast Augmentation Surgery

Directory of Open Access Journals (Sweden)

Daniel Nunes e Silva, MD

2017-09-01

Full Text Available Summary:. Generally, the main complications of silicone implantation are local symptoms. However, some patients develop late-onset systemic symptoms often associated with a rare form of hyperactive immune response, as part of a syndrome known as autoimmune syndrome induced by adjuvants (ASIA. Reported cases of ASIA have shown resolution with explantation, but not with immunomodulatory therapy. In this report, we described a case of a previously healthy 23-year-old woman, who has undergone silicone breast implant augmentation, for aesthetic reasons, and developed localized cutaneous impairment 3 years postsurgery. She received a diagnosis of ASIA with a new presentation: Lupus-like manifestation through localized cutaneous impairment. This patient’s symptoms were managed without the need for surgical intervention, which has not been previously reported, because the patient did not want an explantation for aesthetic reasons. The patient was started on hydroxychloroquine, 400 mg per day, and remains asymptomatic after 2 years of treatment. The exact predisposition to ASIA is still unknown. Without implant explantation and with immunomodulatory treatment, this patient’s condition substantially improved. Based on our current understanding of this disease, it might not be prudent to indicate breast augmentation with silicone implants in patients with documented autoimmune reaction to an adjuvant, an established autoimmune condition, or genetic predisposition. However, if a patient does develop silicone-induced ASIA, explantation is no longer the only successfully reported option, as these symptoms can be managed with immune suppression.

Thermoelectric characteristics of Pt-silicide/silicon multi-layer structured p-type silicon

International Nuclear Information System (INIS)

Choi, Wonchul; Jun, Dongseok; Kim, Soojung; Shin, Mincheol; Jang, Moongyu

2015-01-01

Electric and thermoelectric properties of silicide/silicon multi-layer structured devices were investigated with the variation of silicide/silicon heterojunction numbers from 3 to 12 layers. For the fabrication of silicide/silicon multi-layered structure, platinum and silicon layers are repeatedly sputtered on the (100) silicon bulk substrate and rapid thermal annealing is carried out for the silicidation. The manufactured devices show ohmic current–voltage (I–V) characteristics. The Seebeck coefficient of bulk Si is evaluated as 195.8 ± 15.3 μV/K at 300 K, whereas the 12 layered silicide/silicon multi-layer structured device is evaluated as 201.8 ± 9.1 μV/K. As the temperature increases to 400 K, the Seebeck coefficient increases to 237.2 ± 4.7 μV/K and 277.0 ± 1.1 μV/K for bulk and 12 layered devices, respectively. The increase of Seebeck coefficient in multi-layered structure is mainly attributed to the electron filtering effect due to the Schottky barrier at Pt-silicide/silicon interface. At 400 K, the thermal conductivity is reduced by about half of magnitude compared to bulk in multi-layered device which shows the efficient suppression of phonon propagation by using Pt-silicide/silicon hetero-junctions. - Highlights: • Silicide/silicon multi-layer structured is proposed for thermoelectric devices. • Electric and thermoelectric properties with the number of layer are investigated. • An increase of Seebeck coefficient is mainly attributed the Schottky barrier. • Phonon propagation is suppressed with the existence of Schottky barrier. • Thermal conductivity is reduced due to the suppression of phonon propagation

Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

KAUST Repository

Chaieb, Sahraoui

2015-04-09

Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

KAUST Repository

Chaieb, Saharoui; Mughal, Asad Jahangir

2015-01-01

Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

The effect of silicon crystallographic orientation on the formation of silicon nanoclusters during anodic electrochemical etching

International Nuclear Information System (INIS)

Timokhov, D. F.; Timokhov, F. P.

2009-01-01

Possible ways for increasing the photoluminescence quantum yield of porous silicon layers have been investigated. The effect of the anodization parameters on the photoluminescence properties for porous silicon layers formed on silicon substrates with different crystallographic orientations was studied. The average diameters for silicon nanoclusters are calculated from the photoluminescence spectra of porous silicon. The influence of the substrate crystallographic orientation on the photoluminescence quantum yield of porous silicon is revealed. A model explaining the effect of the substrate orientation on the photoluminescence properties for the porous silicon layers formed by anode electrochemical etching is proposed.

Photoluminescence of Mg_2Si films fabricated by magnetron sputtering

International Nuclear Information System (INIS)

Liao, Yang-Fang; Xie, Quan; Xiao, Qing-Quan; Chen, Qian; Fan, Meng-Hui; Xie, Jing; Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di

2017-01-01

Highlights: • High quality Mg_2Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg_2Si films was reported. • The Mg_2Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg_2Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg_2Si-based light-emitting devices, Mg_2Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg_2Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg_2Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg_2Si film on Si (111) displays polycrystalline structure, whereas Mg_2Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg_2Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg_2Si films was observed for the first time. The PL emission wavelengths of Mg_2Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg_2Si films on glass substrate is much larger than that of Mg_2Si film on Si (111) substrate. The activation energy of 18 meV is

Joining elements of silicon carbide

International Nuclear Information System (INIS)

Olson, B.A.

1979-01-01

A method of joining together at least two silicon carbide elements (e.g.in forming a heat exchanger) is described, comprising subjecting to sufficiently non-oxidizing atmosphere and sufficiently high temperature, material placed in space between the elements. The material consists of silicon carbide particles, carbon and/or a precursor of carbon, and silicon, such that it forms a joint joining together at least two silicon carbide elements. At least one of the elements may contain silicon. (author)

Graphitized silicon carbide microbeams: wafer-level, self-aligned graphene on silicon wafers

International Nuclear Information System (INIS)

Cunning, Benjamin V; Ahmed, Mohsin; Mishra, Neeraj; Kermany, Atieh Ranjbar; Iacopi, Francesca; Wood, Barry

2014-01-01

Currently proven methods that are used to obtain devices with high-quality graphene on silicon wafers involve the transfer of graphene flakes from a growth substrate, resulting in fundamental limitations for large-scale device fabrication. Moreover, the complex three-dimensional structures of interest for microelectromechanical and nanoelectromechanical systems are hardly compatible with such transfer processes. Here, we introduce a methodology for obtaining thousands of microbeams, made of graphitized silicon carbide on silicon, through a site-selective and wafer-scale approach. A Ni-Cu alloy catalyst mediates a self-aligned graphitization on prepatterned SiC microstructures at a temperature that is compatible with silicon technologies. The graphene nanocoating leads to a dramatically enhanced electrical conductivity, which elevates this approach to an ideal method for the replacement of conductive metal films in silicon carbide-based MEMS and NEMS devices. (paper)

Silicon liquid for cooling coal cutter loader motors

Energy Technology Data Exchange (ETDEWEB)

Donets, I K; Sukhanov, V V; Tsingarelli, E P; Dmitrenko, Yu I; Kovalev, E B

1983-05-01

Several silicones were tested with a view to their suitability for use as a cutter loader engine coolant. None were particularly toxic and FM-5.6AP had the best engineering properties; a full toxicological evaluation was therefore made of it. Threshold concentrations of FM-5.6AP were 450 and 24.1 mg/m/sup 3/ for the acute and chronic tests respectively. Increased temperature (120 C) did not affect the toxicity of the vapors significantly. No influence on the phagocytosis, deposition and elimination of coal dust in the lungs was found. Tests carried out underground in a Donbass mine revealed no harmful effects on miners. Laboratory and mine tests using an EhKVZh-315 cutter loader engine revealed that the quantity of FM-5.6AP vapor present in the air flow is less than the detectable minimum (0.01 mg/ml). It may therefore safely be used as a dielectric liquid in cutter loader engines.

Use of porous silicon to minimize oxidation induced stacking fault defects in silicon

International Nuclear Information System (INIS)

Shieh, S.Y.; Evans, J.W.

1992-01-01

This paper presents methods for minimizing stacking fault defects, generated during oxidation of silicon, include damaging the back of the wafer or depositing poly-silicon on the back. In either case a highly defective structure is created and this is capable of gettering either self-interstitials or impurities which promote nucleation of stacking fault defects. A novel method of minimizing these defects is to form a patch of porous silicon on the back of the wafer by electrochemical etching. Annealing under inert gas prior to oxidation may then result in the necessary gettering. Experiments were carried out in which wafers were subjected to this treatment. Subsequent to oxidation, the wafers were etched to remove oxide and reveal defects. The regions of the wafer adjacent to the porous silicon patch were defect-free, whereas remote regions had defects. Deep level transient spectroscopy has been used to examine the gettering capability of porous silicon, and the paper discusses the mechanism by which the porous silicon getters

Indentation fatigue in silicon nitride, alumina and silicon carbide ...

Indian Academy of Sciences (India)

Repeated indentation fatigue (RIF) experiments conducted on the same spot of different structural ceramics viz. a hot pressed silicon nitride (HPSN), sintered alumina of two different grain sizes viz. 1 m and 25 m, and a sintered silicon carbide (SSiC) are reported. The RIF experiments were conducted using a Vicker's ...

Silicon web process development

Science.gov (United States)

Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.; Skutch, M. E.; Driggers, J. M.; Hopkins, R. H.

1981-01-01

The silicon web process takes advantage of natural crystallographic stabilizing forces to grow long, thin single crystal ribbons directly from liquid silicon. The ribbon, or web, is formed by the solidification of a liquid film supported by surface tension between two silicon filaments, called dendrites, which border the edges of the growing strip. The ribbon can be propagated indefinitely by replenishing the liquid silicon as it is transformed to crystal. The dendritic web process has several advantages for achieving low cost, high efficiency solar cells. These advantages are discussed.

Characterization of silicon oxynitride films prepared by the simultaneous implantation of oxygen and nitrogen ions into silicon

International Nuclear Information System (INIS)

Hezel, R.; Streb, W.

1985-01-01

Silicon oxynitride films about 5 nm in thickness were prepared by simultaneously implanting 5 keV oxygen and nitrogen ions into silicon at room temperature up to saturation. These films with concentrations ranging from pure silicon oxide to silicon nitride were characterized using Auger electron spectroscopy, electron energy loss spectroscopy and depth-concentration profiling. The different behaviour of the silicon oxynitride films compared with those of silicon oxide and silicon nitride with regard to thermal stability and hardness against electron and argon ion irradiation is pointed out. (Auth.)

Determination of silicon and aluminum in silicon carbide nanocrystals by high-resolution continuum source graphite furnace atomic absorption spectrometry.

Science.gov (United States)

Dravecz, Gabriella; Bencs, László; Beke, Dávid; Gali, Adam

2016-01-15

The determination of Al contaminant and the main component Si in silicon carbide (SiC) nanocrystals with the size-distribution of 1-8nm dispersed in an aqueous solution was developed using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS). The vaporization/atomization processes were investigated in a transversally heated graphite atomizer by evaporating solution samples of Al and Si preserved in various media (HCl, HNO3). For Si, the best results were obtained by applying a mixture of 5µg Pd plus 5µg Mg, whereas for Al, 10µg Mg (each as nitrate solution) was dispensed with the samples, but the results obtained without modifier were found to be better. This way a maximum pyrolysis temperature of 1200°C for Si and 1300°C for Al could be used, and the optimum (compromise) atomization temperature was 2400°C for both analytes. The Si and Al contents of different sized SiC nanocrystals, dispersed in aqueous solutions, were determined against aqueous (external) calibration standards. The correlation coefficients (R values) of the calibrations were found to be 0.9963 for Si and 0.9991 for Al. The upper limit of the linear calibration range was 2mg/l Si and 0.25mg/l Al. The limit of detection was 3µg/l for Si and 0.5µg/l for Al. The characteristic mass (m0) was calculated to be 389pg Si and 6.4pg Al. The Si and Al content in the solution samples were found to be in the range of 1.0-1.7mg/l and 0.1-0.25mg/l, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Silicon germanium mask for deep silicon etching

KAUST Repository

Serry, Mohamed

2014-07-29

Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

Silicon germanium mask for deep silicon etching

KAUST Repository

Serry, Mohamed; Rubin, Andrew; Refaat, Mohamed; Sedky, Sherif; Abdo, Mohammad

2014-01-01

Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab

DEFF Research Database (Denmark)

Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.

2015-01-01

An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration....

Effects of total gastrectomy on plasma silicon and amino acid concentrations in men.

Science.gov (United States)

Tatara, Marcin R; Krupski, Witold; Szpetnar, Maria; Dąbrowski, Andrzej; Bury, Paweł; Szabelska, Anna; Charuta, Anna; Boguszewska-Czubara, Anna; Maciejewski, Ryszard; Wallner, Grzegorz

2015-12-01

The aim of the study was to determine one-year effects of total gastrectomy on plasma silicon and free amino acid concentrations in patients and evaluate changes of volumetric bone mineral density (vBMD) in lumbar spine. Eight patients were enrolled to the control (CTR) group. Six patients subjected to total gastrectomy (GX group) were included to the experimental group. vBMD in trabecular and cortical bone was measured in lumbar vertebrae at baseline (before surgery) and one year later using quantitative computed tomography. Plasma concentrations of silicon and free amino acids were determined at baseline and one year later using photometric method and ion-exchange chromatography. Body weights within CTR and GX groups were not different after one-year follow-up when compared to the baseline values (P > 0.05). An average annual decrease of vBMD in the trabecular bone in the gastrectomized patients reached 15.0% in lumbar spine and was significantly different in comparison to the percentage changes observed in CTR group (P = 0.02). One-year percentage change of vBMD in the cortical bone in L1 and L2 has shown significantly decreased values by 10.5 and 9.1% in the GX group when compared to the percentage change observed in the controls (P silicon was significantly lowered by 26.7% one year after the total gastrectomy when compared to the baseline value (P = 0.009). Total gastrectomy in patients has induced severe osteoporotic changes in lumbar spine within one-year period. The observed osteoporotic changes were associated with decreased plasma concentration of silicon indicating importance of exocrine and endocrine functions of stomach for silicon homeostasis maintenance. Gastrectomy-induced bone loss was not related to decreased amino acid concentration in plasma obtained from overnight fasted patients. © 2015 by the Society for Experimental Biology and Medicine.

Analysis of Silicones Released from Household Items and Baby Articles by Direct Analysis in Real Time-Mass Spectrometry

Science.gov (United States)

Gross, Jürgen H.

2015-03-01

Direct analysis in real time-mass spectrometry (DART-MS) enables screening of articles of daily use made of polydimethylsiloxanes (PDMS), commonly known as silicone rubber, to assess their tendency to release low molecular weight silicone oligomers. DART-MS analyses were performed on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Flexible silicone baking molds, a watch band, and a dough scraper, as baby articles different brands of pacifiers, nipples, and a teething ring have been examined. While somewhat arbitrarily chosen, the set can be regarded as representative of household items, baby articles, and other objects made of silicone rubber. For comparison, two brands of silicone septa and as blanks a glass slide and a latex pacifier were included. Differences between the objects were mainly observed in terms of molecular weight distribution and occasional release of other compounds in addition to PDMS. Other than that, all objects made of silicone rubber released significant amounts of PDMS during DART analysis. To provide a coarse quantification, a calibration based on silicone oil was established, which delivered PDMS losses from 20 μg to >100 μg during the 16-s period per measurement. Also, the extraction of baking molds in rapeseed oil demonstrated a PDMS release at the level of 1 μg mg-1. These findings indicate a potential health hazard from frequent or long-term use of such items. This work does not intend to blame certain brands of such articles. Nonetheless, a higher level of awareness of this source of daily silicone intake is suggested.

Selective formation of porous silicon

Science.gov (United States)

Fathauer, Robert W. (Inventor); Jones, Eric W. (Inventor)

1993-01-01

A pattern of porous silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H2O. The defected crystal will preferentially etch to form a pattern of porous silicon. When the amorphous content of the porous silicon exceeds 70 percent, the porous silicon pattern emits visible light at room temperature.

Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide

OpenAIRE

K?nig, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

2017-01-01

All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusi...

Optical property of silicon quantum dots embedded in silicon nitride by thermal annealing

Energy Technology Data Exchange (ETDEWEB)

Kim, Baek Hyun, E-mail: bhkim@andrew.cmu.ed [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United Sates (United States); Davis, Robert F. [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United Sates (United States); Park, Seong-Ju [Nanophotonic Semiconductors Laboratory, Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, 500-712 (Korea, Republic of)

2010-01-01

We present the effects on the thermal annealing of silicon quantum dots (Si QDs) embedded in silicon nitride. The improved photoluminescence (PL) intensities and the red-shifted PL spectra were obtained with annealing treatment in the range of 700 to 1000 {sup o}C. The shifts of PL spectra were attributed to the increase in the size of Si QDs. The improvement of the PL intensities was also attributed to the reduction of point defects at Si QD/silicon nitride interface and in the silicon nitride due to hydrogen passivation effects.

Silicon photonics fundamentals and devices

CERN Document Server

Deen, M Jamal

2012-01-01

The creation of affordable high speed optical communications using standard semiconductor manufacturing technology is a principal aim of silicon photonics research. This would involve replacing copper connections with optical fibres or waveguides, and electrons with photons. With applications such as telecommunications and information processing, light detection, spectroscopy, holography and robotics, silicon photonics has the potential to revolutionise electronic-only systems. Providing an overview of the physics, technology and device operation of photonic devices using exclusively silicon and related alloys, the book includes: * Basic Properties of Silicon * Quantum Wells, Wires, Dots and Superlattices * Absorption Processes in Semiconductors * Light Emitters in Silicon * Photodetectors , Photodiodes and Phototransistors * Raman Lasers including Raman Scattering * Guided Lightwaves * Planar Waveguide Devices * Fabrication Techniques and Material Systems Silicon Photonics: Fundamentals and Devices outlines ...

Twenty-fold plasmon-induced enhancement of radiative emission rate in silicon nanocrystals embedded in silicon dioxide

International Nuclear Information System (INIS)

Gardelis, S; Gianneta, V.; Nassiopoulou, A.G

2016-01-01

We report on a 20-fold enhancement of the integrated photoluminescence (PL) emission of silicon nanocrystals, embedded in a matrix of silicon dioxide, induced by excited surface plasmons from silver nanoparticles, which are located in the vicinity of the silicon nanocrystals and separated from them by a silicon dioxide layer of a few nanometers. The electric field enhancement provided by the excited surface plasmons increases the absorption cross section and the emission rate of the nearby silicon nanocrystals, resulting in the observed enhancement of the photoluminescence, mainly attributed to a 20-fold enhancement in the emission rate of the silicon nanocrystals. The observed remarkable improvement of the PL emission makes silicon nanocrystals very useful material for photonic, sensor and solar cell applications.

Direct Production of Silicones From Sand

Energy Technology Data Exchange (ETDEWEB)

Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

2001-09-30

Silicon, in the form of silica and silicates, is the second most abundant element in the earth's crust. However the synthesis of silicones (scheme 1) and almost all organosilicon chemistry is only accessible through elemental silicon. Silicon dioxide (sand or quartz) is converted to chemical-grade elemental silicon in an energy intensive reduction process, a result of the exceptional thermodynamic stability of silica. Then, the silicon is reacted with methyl chloride to give a mixture of methylchlorosilanes catalyzed by cooper containing a variety of tract metals such as tin, zinc etc. The so-called direct process was first discovered at GE in 1940. The methylchlorosilanes are distilled to purify and separate the major reaction components, the most important of which is dimethyldichlorosilane. Polymerization of dimethyldichlorosilane by controlled hydrolysis results in the formation of silicone polymers. Worldwide, the silicones industry produces about 1.3 billion pounds of the basic silicon polymer, polydimethylsiloxane.

Flexible Thermoelectric Generators on Silicon Fabric

KAUST Repository

Sevilla, Galo T.

2012-11-01

In this work, the development of a Thermoelectric Generator on Flexible Silicon Fabric is explored to extend silicon electronics for flexible platforms. Low cost, easily deployable plastic based flexible electronics are of great interest for smart textile, wearable electronics and many other exciting applications. However, low thermal budget processing and fundamentally limited electron mobility hinders its potential to be competitive with well established and highly developed silicon technology. The use of silicon in flexible electronics involve expensive and abrasive materials and processes. In this work, high performance flexible thermoelectric energy harvesters are demonstrated from low cost bulk silicon (100) wafers. The fabrication of the micro- harvesters was done using existing silicon processes on silicon (100) and then peeled them off from the original substrate leaving it for reuse. Peeled off silicon has 3.6% thickness of bulk silicon reducing the thermal loss significantly and generating nearly 30% more output power than unpeeled harvesters. The demonstrated generic batch processing shows a pragmatic way of peeling off a whole silicon circuitry after conventional fabrication on bulk silicon wafers for extremely deformable high performance integrated electronics. In summary, by using a novel, low cost process, this work has successfully integrated existing and highly developed fabrication techniques to introduce a flexible energy harvester for sustainable applications.

Subwavelength silicon photonics

International Nuclear Information System (INIS)

Cheben, P.; Bock, P.J.; Schmid, J.H.; Lapointe, J.; Janz, S.; Xu, D.-X.; Densmore, A.; Delage, A.; Lamontagne, B.; Florjanczyk, M.; Ma, R.

2011-01-01

With the goal of developing photonic components that are compatible with silicon microelectronic integrated circuits, silicon photonics has been the subject of intense research activity. Silicon is an excellent material for confining and manipulating light at the submicrometer scale. Silicon optoelectronic integrated devices have the potential to be miniaturized and mass-produced at affordable cost for many applications, including telecommunications, optical interconnects, medical screening, and biological and chemical sensing. We review recent advances in silicon photonics research at the National Research Council Canada. A new type of optical waveguide is presented, exploiting subwavelength grating (SWG) effect. We demonstrate subwavelength grating waveguides made of silicon, including practical components operating at telecom wavelengths: input couplers, waveguide crossings and spectrometer chips. SWG technique avoids loss and wavelength resonances due to diffraction effects and allows for single-mode operation with direct control of the mode confinement by changing the refractive index of a waveguide core over a range as broad as 1.6 - 3.5 simply by lithographic patterning. The light can be launched to these waveguides with a coupling loss as small as 0.5 dB and with minimal wavelength dependence, using coupling structures similar to that shown in Fig. 1. The subwavelength grating waveguides can cross each other with minimal loss and negligible crosstalk which allows massive photonic circuit connectivity to overcome the limits of electrical interconnects. These results suggest that the SWG waveguides could become key elements for future integrated photonic circuits. (authors)

Silicon photonic integration in telecommunications

Directory of Open Access Journals (Sweden)

Christopher Richard Doerr

2015-08-01

Full Text Available Silicon photonics is the guiding of light in a planar arrangement of silicon-based materials to perform various functions. We focus here on the use of silicon photonics to create transmitters and receivers for fiber-optic telecommunications. As the need to squeeze more transmission into a given bandwidth, a given footprint, and a given cost increases, silicon photonics makes more and more economic sense.

Silicon microphones - a Danish perspective

DEFF Research Database (Denmark)

Bouwstra, Siebe; Storgaard-Larsen, Torben; Scheeper, Patrick

1998-01-01

Two application areas of microphones are discussed, those for precision measurement and those for hearing instruments. Silicon microphones are under investigation for both areas, and Danish industry plays a key role in both. The opportunities of silicon, as well as the challenges and expectations......, are discussed. For precision measurement the challenge for silicon is large, while for hearing instruments silicon seems to be very promising....

Integrated silicon optoelectronics

CERN Document Server

Zimmermann, Horst

2000-01-01

'Integrated Silicon Optoelectronics'assembles optoelectronics and microelectronics The book concentrates on silicon as the major basis of modern semiconductor devices and circuits Starting from the basics of optical emission and absorption and from the device physics of photodetectors, the aspects of the integration of photodetectors in modern bipolar, CMOS, and BiCMOS technologies are discussed Detailed descriptions of fabrication technologies and applications of optoelectronic integrated circuits are included The book, furthermore, contains a review of the state of research on eagerly expected silicon light emitters In order to cover the topic of the book comprehensively, integrated waveguides, gratings, and optoelectronic power devices are included in addition Numerous elaborate illustrations promote an easy comprehension 'Integrated Silicon Optoelectronics'will be of value to engineers, physicists, and scientists in industry and at universities The book is also recommendable for graduate students speciali...

Process for making silicon

Science.gov (United States)

Levin, Harry (Inventor)

1987-01-01

A reactor apparatus (10) adapted for continuously producing molten, solar grade purity elemental silicon by thermal reaction of a suitable precursor gas, such as silane (SiH.sub.4), is disclosed. The reactor apparatus (10) includes an elongated reactor body (32) having graphite or carbon walls which are heated to a temperature exceeding the melting temperature of silicon. The precursor gas enters the reactor body (32) through an efficiently cooled inlet tube assembly (22) and a relatively thin carbon or graphite septum (44). The septum (44), being in contact on one side with the cooled inlet (22) and the heated interior of the reactor (32) on the other side, provides a sharp temperature gradient for the precursor gas entering the reactor (32) and renders the operation of the inlet tube assembly (22) substantially free of clogging. The precursor gas flows in the reactor (32) in a substantially smooth, substantially axial manner. Liquid silicon formed in the initial stages of the thermal reaction reacts with the graphite or carbon walls to provide a silicon carbide coating on the walls. The silicon carbide coated reactor is highly adapted for prolonged use for production of highly pure solar grade silicon. Liquid silicon (20) produced in the reactor apparatus (10) may be used directly in a Czochralski or other crystal shaping equipment.

Silicon etch process

International Nuclear Information System (INIS)

Day, D.J.; White, J.C.

1984-01-01

A silicon etch process wherein an area of silicon crystal surface is passivated by radiation damage and non-planar structure produced by subsequent anisotropic etching. The surface may be passivated by exposure to an energetic particle flux - for example an ion beam from an arsenic, boron, phosphorus, silicon or hydrogen source, or an electron beam. Radiation damage may be used for pattern definition and/or as an etch stop. Ethylenediamine pyrocatechol or aqueous potassium hydroxide anisotropic etchants may be used. The radiation damage may be removed after etching by thermal annealing. (author)

Investigation of the interface region between a porous silicon layer and a silicon substrate

International Nuclear Information System (INIS)

Lee, Ki-Won; Park, Dae-Kyu; Kim, Young-You; Shin, Hyun-Joon

2005-01-01

Atomic force microscopy (AFM) measurement and X-ray diffraction (XRD) analysis were performed to investigate the physical and structural characteristics of the interface region between a porous silicon layer and a silicon substrate. We discovered that, when anodization time was increased under a constant current density, the Si crystallites in the interface region became larger and formed different lattice parameters than observed in the porous silicon layer. Secondary ion mass spectrometry (SIMS) analysis also revealed that the Si was more concentrated in the interface region than in the porous silicon layer. These results were interpreted by the deficiency of the HF solution in reaching to the interface through the pores during the porous silicon formation

Vapor Pressure and Evaporation Coefficient of Silicon Monoxide over a Mixture of Silicon and Silica

Science.gov (United States)

Ferguson, Frank T.; Nuth, Joseph A., III

2012-01-01

The evaporation coefficient and equilibrium vapor pressure of silicon monoxide over a mixture of silicon and vitreous silica have been studied over the temperature range (1433 to 1608) K. The evaporation coefficient for this temperature range was (0.007 plus or minus 0.002) and is approximately an order of magnitude lower than the evaporation coefficient over amorphous silicon monoxide powder and in general agreement with previous measurements of this quantity. The enthalpy of reaction at 298.15 K for this reaction was calculated via second and third law analyses as (355 plus or minus 25) kJ per mol and (363.6 plus or minus 4.1) kJ per mol respectively. In comparison with previous work with the evaporation of amorphous silicon monoxide powder as well as other experimental measurements of the vapor pressure of silicon monoxide gas over mixtures of silicon and silica, these systems all tend to give similar equilibrium vapor pressures when the evaporation coefficient is correctly taken into account. This provides further evidence that amorphous silicon monoxide is an intimate mixture of small domains of silicon and silica and not strictly a true compound.

High temperature corrosion of silicon carbide and silicon nitride in the presence of chloride compound

International Nuclear Information System (INIS)

McNallan, M.

1993-01-01

Silicon carbide and silicon nitride are resistant to oxidation because a protective silicon dioxide films on their surfaces in most oxidizing environments. Chloride compounds can attack the surface in two ways: 1) chlorine can attack the silicon directly to form a volatile silicon chloride compound or 2) alkali compounds combined with the chlorine can be transported to the surface where they flux the silica layer by forming stable alkali silicates. Alkali halides have enough vapor pressure that a sufficient quantity of alkali species to cause accelerated corrosion can be transported to the ceramic surface without the formation of a chloride deposit. When silicon carbide is attacked simultaneously by chlorine and oxygen, the corrosion products include both volatile and condensed spices. Silicon nitride is much more resistance to this type of attack than silicon carbide. Silicon based ceramics are exposed to oxidizing gases in the presence of alkali chloride vapors, the rate of corrosion is controlled primarily by the driving force for the formation of alkali silicate, which can be quantified as the activity of the alkali oxide in equilibrium with the corrosive gas mixture. In a gas mixture containing a fixed partial pressure of KCl, the rate of corrosion is accelerated by increasing the concentration of water vapor and inhibited by increasing the concentration of HCl. Similar results have been obtained for mixtures containing other alkalis and halogens. (Orig./A.B.)

Peripheral blood picture changes induced by chronic radone and silicon dioxide treatment (in combination or separately)

International Nuclear Information System (INIS)

Ivanov, Z.; Dermendzhiev, Kh.; Nikolova, M.

1975-01-01

Peripheral blood changes have been studied in rats after the following treatments: 4 hours daily for six months with a radon concentration of 1.10 -10 Ci/1 (group I), 1.10 -12 Ci/1 (group II) 50 mg pure silicon dioxide in 1 ml physiological solution (group III), and intratracheal incorporation of radon concentration in air of 1.10 -10 Ci/1 and silicon dioxide (group IV). Examinations during the third and sixth month after the start of experiment showed development of leukopenia in groups I, III and IV; lymphopenia was established in groups I and IV, and lymphocytosis in group III. Atypical morphological changes were observed in red blood cells. (A.B.)

RBS/channeling analysis of hydrogen-implanted single crystals of FZ silicon and 6H silicon

International Nuclear Information System (INIS)

Irwin, R.B.

1984-01-01

Single crystals of FZ silicon and 6H silicon carbide were implanted with hydrogen ions (50 and 80 keV, respectively) to fluences from 2 x 10 16 H + /cm 2 to 2 x 10 18 H+/cm 2 . The implantations were carried out at three temperatures: approx.95K, 300 K, and approx.800 K. Swelling of the samples was measured by surface profilometry. RBS/channeling was used to obtain the damage profiles and to determine the amount of hydrogen retained in the lattice. The damage profiles are centered around X/sub m/ for the implants into silicon and around R/sub p/ for silicon carbide. For silicon carbide implanted at 95 K and 300 K and for silicon implanted at 95 K, the peak damage region is amorphous for fluences above 8 x 10 16 H + /cm 2 , 4 x 10 17 H + /cm 2 , and 2 x 10 17 H + /cm 2 , respectively. Silicon implanted at 300 and 800 K and silicon carbide implanted at 800 K remain crystalline up to fluences of 1 x 10 18 H + /cm 2 . The channeling damage results agree with previously reported TEM and electron diffraction data. The predictions of a simple disorder-accumulation model with a linear annealing term explains qualitatively the observed damage profiles in silicon carbide. Quantitatively, however, the model predicts faster development of the damage profiles than is observed at low fluences in both silicon and silicon carbide. For samples implanted at 300 and 800 K, the model also predicts substantially less peak disorder than is observed. The effect of the surface, the retained hydrogen, the shape of S/sub D/(X), and the need for a nonlinear annealing term may be responsible for the discrepancy

Quantum mechanical theory of epitaxial transformation of silicon to silicon carbide

International Nuclear Information System (INIS)

Kukushkin, S A; Osipov, A V

2017-01-01

The paper focuses on the study of transformation of silicon crystal into silicon carbide crystal via substitution reaction with carbon monoxide gas. As an example, the Si(1 0 0) surface is considered. The cross section of the potential energy surface of the first stage of transformation along the reaction pathway is calculated by the method of nudged elastic bands. It is found that in addition to intermediate states associated with adsorption of CO and SiO molecules on the surface, there is also an intermediate state in which all the atoms are strongly bonded to each other. This intermediate state significantly reduces the activation barrier of transformation down to 2.6 eV. The single imaginary frequencies corresponding to the two transition states of this transformation are calculated, one of which is reactant-like, whereas the other is product-like. By methods of quantum chemistry of solids, the second stage of this transformation is described, namely, the transformation of precarbide silicon into silicon carbide. Energy reduction per one cell is calculated for this ‘collapse’ process, and bond breaking energy is also found. Hence, it is concluded that the smallest size of the collapsing islet is 30 nm. It is shown that the chemical bonds of the initial silicon crystal are coordinately replaced by the bonds between Si and C in silicon carbide, which leads to a high quality of epitaxy and a low concentration of misfit dislocations. (paper)

Silicon Nanocrystal Synthesis in Microplasma Reactor

Science.gov (United States)

Nozaki, Tomohiro; Sasaki, Kenji; Ogino, Tomohisa; Asahi, Daisuke; Okazaki, Ken

Nanocrystalline silicon particles with grains smaller than 5 nm are widely recognized as a key material in optoelectronic devices, lithium battery electrodes, and bio-medical labels. Another important characteristic is that silicon is an environmentally safe material that is used in numerous silicon technologies. To date, several synthesis methods such as sputtering, laser ablation, and plasma-enhanced chemical vapor deposition (PECVD) based on low-pressure silane chemistry (SiH4) have been developed for precise control of size and density distributions of silicon nanocrystals. In this study, we explore the possibility of microplasma technologies for efficient production of mono-dispersed nanocrystalline silicon particles on a micrometer-scale, continuous-flow plasma reactor operated at atmospheric pressure. Mixtures of argon, hydrogen, and silicon tetrachloride were activated using a very-high-frequency (144 MHz) power source in a capillary glass tube with volume of less than 1 μl. Fundamental plasma parameters of the microplasma were characterized using optical emission spectroscopy, which respectively indicated electron density of 1015 cm-3, argon excitation temperature of 5000 K, and rotational temperature of 1500 K. Such high-density non-thermal reactive plasma can decompose silicon tetrachloride into atomic silicon to produce supersaturated silicon vapor, followed by gas-phase nucleation via three-body collision: particle synthesis in high-density plasma media is beneficial for promoting nucleation processes. In addition, further growth of silicon nuclei can be terminated in a short-residence-time reactor. Micro-Raman scattering spectra showed that as-deposited particles are mostly amorphous silicon with a small fraction of silicon nanocrystals. Transmission electron micrography confirmed individual 3-15 nm silicon nanocrystals. Although particles were not mono-dispersed, they were well separated and not coagulated.

Nanostructured silicon for thermoelectric

Science.gov (United States)

Stranz, A.; Kähler, J.; Waag, A.; Peiner, E.

2011-06-01

Thermoelectric modules convert thermal energy into electrical energy and vice versa. At present bismuth telluride is the most widely commercial used material for thermoelectric energy conversion. There are many applications where bismuth telluride modules are installed, mainly for refrigeration. However, bismuth telluride as material for energy generation in large scale has some disadvantages. Its availability is limited, it is hot stable at higher temperatures (>250°C) and manufacturing cost is relatively high. An alternative material for energy conversion in the future could be silicon. The technological processing of silicon is well advanced due to the rapid development of microelectronics in recent years. Silicon is largely available and environmentally friendly. The operating temperature of silicon thermoelectric generators can be much higher than of bismuth telluride. Today silicon is rarely used as a thermoelectric material because of its high thermal conductivity. In order to use silicon as an efficient thermoelectric material, it is necessary to reduce its thermal conductivity, while maintaining high electrical conductivity and high Seebeck coefficient. This can be done by nanostructuring into arrays of pillars. Fabrication of silicon pillars using ICP-cryogenic dry etching (Inductive Coupled Plasma) will be described. Their uniform height of the pillars allows simultaneous connecting of all pillars of an array. The pillars have diameters down to 180 nm and their height was selected between 1 micron and 10 microns. Measurement of electrical resistance of single silicon pillars will be presented which is done in a scanning electron microscope (SEM) equipped with nanomanipulators. Furthermore, measurement of thermal conductivity of single pillars with different diameters using the 3ω method will be shown.

Studies on the reactive melt infiltration of silicon and silicon-molybdenum alloys in porous carbon

Science.gov (United States)

Singh, M.; Behrendt, D. R.

1992-01-01

Investigations on the reactive melt infiltration of silicon and silicon-1.7 and 3.2 at percent molybdenum alloys into porous carbon preforms have been carried out by process modeling, differential thermal analysis (DTA) and melt infiltration experiments. These results indicate that the initial pore volume fraction of the porous carbon preform is a critical parameter in determining the final composition of the raction-formed silicon carbide and other residual phases. The pore size of the carbon preform is very detrimental to the exotherm temperatures due to liquid silicon-carbon reactions encountered during the reactive melt infiltration process. A possible mechanism for the liquid silicon-porous (glassy) carbon reaction has been proposed. The composition and microstructure of the reaction-formed silicon carbide has been discussed in terms of carbon preform microstructures, infiltration materials, and temperatures.

1366 Project Silicon: Reclaiming US Silicon PV Leadership

Energy Technology Data Exchange (ETDEWEB)

Lorenz, Adam [1366 Technologies, Bedford, MA (United States)

2016-02-16

1366 Technologies’ Project Silicon addresses two of the major goals of the DOE’s PV Manufacturing Initiative Part 2 program: 1) How to reclaim a strong silicon PV manufacturing presence and; 2) How to lower the levelized cost of electricity (“LCOE”) for solar to $0.05-$0.07/kWh, enabling wide-scale U.S. market adoption. To achieve these two goals, US companies must commercialize disruptive, high-value technologies that are capable of rapid scaling, defensible from foreign competition, and suited for US manufacturing. These are the aims of 1366 Technologies Direct Wafer ™ process. The research conducted during Project Silicon led to the first industrial scaling of 1366’s Direct Wafer™ process – an innovative, US-friendly (efficient, low-labor content) manufacturing process that destroys the main cost barrier limiting silicon PV cost-reductions: the 35-year-old grand challenge of making quality wafers (40% of the cost of modules) without the cost and waste of sawing. The SunPath program made it possible for 1366 Technologies to build its demonstration factory, a key and critical step in the Company’s evolution. The demonstration factory allowed 1366 to build every step of the process flow at production size, eliminating potential risk and ensuring the success of the Company’s subsequent scaling for a 1 GW factory to be constructed in Western New York in 2016 and 2017. Moreover, the commercial viability of the Direct Wafer process and its resulting wafers were established as 1366 formed key strategic partnerships, gained entry into the $8B/year multi-Si wafer market, and installed modules featuring Direct Wafer products – the veritable proving grounds for the technology. The program also contributed to the development of three Generation 3 Direct Wafer furnaces. These furnaces are the platform for copying intelligently and preparing our supply chain – large-scale expansion will not require a bigger machine but more machines. SunPath filled the

Silicon-micromachined microchannel plates

CERN Document Server

Beetz, C P; Steinbeck, J; Lemieux, B; Winn, D R

2000-01-01

Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of approx 0.5 to approx 25 mu m, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposite...

Measurement and analysis of quadruple (αγγ) angular correlations for high spin states of 24Mg

International Nuclear Information System (INIS)

Wiedenhoever, I.; Wuosmaa, A. H.; Lister, C. J.; Carpenter, M. P.; Janssens, R. V. F.; Amro, H.; Caggiano, J.; Heinz, A.; Kondev, F. G.; Lauritsen, T.; Siem, S.; Sonzogni, A.; Bhattacharyya, P.; Devlin, M.; Sarantites, D. G.; Sobotka, L. G.

2000-01-01

The high-lying, α-decaying states in 24 Mg have been studied by measuring the complete decay path of α and γ emissions using five segmented Silicon detectors in conjunction with GAMMASPHERE. The authors analyzed the (αγ) triple angular correlations and, for the first time, (αγγ) quadruple correlations. The data analysis is based on a new Fourier transformation technique. The power of the technique is demonstrated

Experiment and Simulation Study on the Amorphous Silicon Photovoltaic Walls

Directory of Open Access Journals (Sweden)

Wenjie Zhang

2014-01-01

Full Text Available Based on comparative study on two amorphous silicon photovoltaic walls (a-Si PV walls, the temperature distribution and the instant power were tested; and with EnergyPlus software, similar models of the walls were built to simulate annual power generation and air conditioning load. On typical sunshine day, the corresponding position temperature of nonventilated PV wall was generally 0.5~1.5°C higher than that of ventilated one, while the power generation was 0.2%~0.4% lower, which was consistent with the simulation results with a difference of 0.41% in annual energy output. As simulation results, in summer, comparing the PV walls with normal wall, the heat per unit area of these two photovoltaic walls was 5.25 kWh/m2 (nonventilated and 0.67 kWh/m2 (ventilated higher, respectively. But in winter the heat loss of nonventilated one was smaller, while ventilated PV wall was similar to normal wall. To annual energy consumption of heating and cooling, the building with ventilated PV wall and normal wall was also similar but slightly better than nonventilated one. Therefore, it is inferred that, at low latitudes, such as Zhuhai, China, air gap ventilation is suitable, while the length to thickness ratio of the air gap needs to be taken into account.

Porous silicon carbide (SIC) semiconductor device

Science.gov (United States)

Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

1996-01-01

Porous silicon carbide is fabricated according to techniques which result in a significant portion of nanocrystallites within the material in a sub 10 nanometer regime. There is described techniques for passivating porous silicon carbide which result in the fabrication of optoelectronic devices which exhibit brighter blue luminescence and exhibit improved qualities. Based on certain of the techniques described porous silicon carbide is used as a sacrificial layer for the patterning of silicon carbide. Porous silicon carbide is then removed from the bulk substrate by oxidation and other methods. The techniques described employ a two-step process which is used to pattern bulk silicon carbide where selected areas of the wafer are then made porous and then the porous layer is subsequently removed. The process to form porous silicon carbide exhibits dopant selectivity and a two-step etching procedure is implemented for silicon carbide multilayers.

Silicon Photonics Cloud (SiCloud)

DEFF Research Database (Denmark)

DeVore, P. T. S.; Jiang, Y.; Lynch, M.

2015-01-01

Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

Evaluation of Schottky and MgO-based tunnelling diodes with different ferromagnets for spin injection in n-Si

International Nuclear Information System (INIS)

Uhrmann, T; Dimopoulos, T; Brueckl, H; Kovacs, A; Kohn, A; Weyers, S; Paschen, U; Smoliner, J

2009-01-01

In this work we present the electrical properties of sputter-deposited ferromagnetic (FM) Schottky diodes and MgO-based tunnelling diodes to n-doped (0 0 1) silicon. The effective Schottky barrier height (SBH) has been evaluated as a function of the FM electrode (Co 70 Fe 30 , Co 40 Fe 40 B 20 and Ni 80 Fe 20 ), the silicon doping density (10 15 to 10 18 cm -3 ), the MgO tunnelling barrier thickness (0, 1.5 and 2.5 nm) and post-deposition annealing up to 400 0 C. The ideality factors of the Schottky diodes are close to unity, indicating transport by thermionic emission and the absence of an interfacial oxide layer, which is confirmed by transmission electron microscopy. The effective SBH is found to be approximately 0.65 eV, independent of the FM material and decreasing with increasing doping density. The changes induced by high temperature annealing at the current-voltage characteristic of the Schottky diodes depend strongly on the FM electrode. The effective SBH for the tunnelling diodes is as low as 0.3 eV, which suggests a high density of oxide and interface traps. It is again independent of the FM electrode, decreasing with increasing doping density and annealing temperature. The inclusion of MgO leads to higher thermal stability of the tunnelling diodes. The measured contact resistance values are discussed with respect to the conductivity mismatch for spin injection and detection.

Influence of the Sr and Mg Alloying Additions on the Bonding Between Matrix and Reinforcing Particles in the AlSi7Mg/SiC-Cg Hybrid Composite

Directory of Open Access Journals (Sweden)

Dolata A. J.

2016-06-01

Full Text Available The aim of the work was to perform adequate selection of the phase composition of the composite designated for permanent - mould casting air compressor pistons. The hybrid composites based on AlSi7Mg matrix alloy reinforced with mixture of silicon carbide (SiC and glassy carbon (Cg particles were fabricated by the stir casting method. It has been shown that the proper selection of chemical composition of matrix alloy and its modification by used magnesium and strontium additions gives possibility to obtain both the advantageous casting properties of composite suspensions as well as good bonding between particles reinforcements and matrix.

The silicon-silicon oxide multilayers utilization as intrinsic layer on pin solar cells

International Nuclear Information System (INIS)

Colder, H.; Marie, P.; Gourbilleau, F.

2008-01-01

Silicon nanostructures are promising candidate for the intrinsic layer on pin solar cells. In this work we report on new material: silicon-rich silicon oxide (SRSO) deposited by reactive magnetron sputtering of a pure silica target and an interesting structure: multilayers consisting of a stack of SRSO and pure silicon oxide layers. Two thicknesses of the SRSO sublayer, t SRSO , are studied 3 nm and 5 nm whereas the thickness of silica sublayer is maintaining at 3 nm. The presence of nanocrystallites of silicon, evidenced by X-Ray diffraction (XRD), leads to photoluminescence (PL) emission at room temperature due to the quantum confinement of the carriers. The PL peak shifts from 1.3 eV to 1.5 eV is correlated to the decreasing of t SRSO from 5 nm down to 3 nm. In the purpose of their potential utilization for i-layer, the optical properties are studied by absorption spectroscopy. The achievement a such structures at promising absorption properties. Moreover by favouring the carriers injection by the tunnel effect between silicon nanograins and silica sublayers, the multilayers seem to be interesting for solar cells

The Influence of Silicon and Multinutrient Fertilizer On the Quality and Chemical Composition of Gazania Rigens ‘Kiss Yellow’, Salvia Farinacea ‘Fairy Queen’ and Verbena ‘Obsession Lilac’ Plants

Directory of Open Access Journals (Sweden)

Dębicz Regina

2017-06-01

Full Text Available Silicon supplementation may lead to positive changes in plant quality, including their appearance. The two-factorial experiment with three ornamental plant taxa Gazania rigens ‘Kiss Yellow’, Salvia farinacea ‘Fairy Queen’ and Verbena ‘Obsession Lilac’ was conducted in the years 2012-2013. The first factor was foliar application of Si in form of ortho-silicic acid stabilized with choline (YaraVita Actisil at the concentrations of 60, 120 and 180 mg·dm-3, while the second was soil application of multinutrient fertilizer (Insol U at the concentrations of 0.25% and 0.50%. Biometric measurements of plants were carried out at the beginning of flowering. The laboratory analyses included the determination of the content of P, K, Ca, Mg and Si as well as chlorophyll content in the leaves. Silicon had a beneficial influence on a majority of the analysed morphological features. Plants reacted best to high silicon doses (120 and 180 mg·dm-3. Particularly beneficial effects were noted with respect to improved flowering of all analysed plant taxa and to the vegetative development of Salvia and Gazania. Insol U supplementation noticeably improved the flowering of Verbena.

Method of forming buried oxide layers in silicon

Science.gov (United States)

Sadana, Devendra Kumar; Holland, Orin Wayne

2000-01-01

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Effects of ion implantation on charges in the silicon--silicon dioxide system

International Nuclear Information System (INIS)

Learn, A.J.; Hess, D.W.

1977-01-01

Structures consisting of thermally grown oxide on silicon were implanted with boron, arsenic, or argon ions. For argon implantation through oxides, an increased fixed oxide charge (Q/sub ss/) was observed with the increase being greater for than for silicon. This effect is attributed to oxygen recoil which produces additional excess ionized silicon in the oxide of a type similar to that arising in thermal oxidation. Fast surface state (N/sub st/) generation was also noted which in most cases obscured the Q/sub ss/ increase. Of various heat treatments tested, only a 900 degreeC anneal in hydrogen annihilated N/sub st/ and allowed Q/sub ss/ measurement. Such N/sub st/ apparently arises as a consequence of implantation damage at the silicon--silicon dioxide interface. With the exception of boron implantations into thick oxides or through aluminum electrodes, reduction of the mobile ionic charge (Q/sub o/) was achieved by implantation. The reduction again is presumably damage related and is not negated by high-temperature annealing but may be counterbalanced by aluminum incorporation in the oxide

High Efficiency, Low Cost Solar Cells Manufactured Using 'Silicon Ink' on Thin Crystalline Silicon Wafers

Energy Technology Data Exchange (ETDEWEB)

Antoniadis, H.

2011-03-01

Reported are the development and demonstration of a 17% efficient 25mm x 25mm crystalline Silicon solar cell and a 16% efficient 125mm x 125mm crystalline Silicon solar cell, both produced by Ink-jet printing Silicon Ink on a thin crystalline Silicon wafer. To achieve these objectives, processing approaches were developed to print the Silicon Ink in a predetermined pattern to form a high efficiency selective emitter, remove the solvents in the Silicon Ink and fuse the deposited particle Silicon films. Additionally, standard solar cell manufacturing equipment with slightly modified processes were used to complete the fabrication of the Silicon Ink high efficiency solar cells. Also reported are the development and demonstration of a 18.5% efficient 125mm x 125mm monocrystalline Silicon cell, and a 17% efficient 125mm x 125mm multicrystalline Silicon cell, by utilizing high throughput Ink-jet and screen printing technologies. To achieve these objectives, Innovalight developed new high throughput processing tools to print and fuse both p and n type particle Silicon Inks in a predetermined pat-tern applied either on the front or the back of the cell. Additionally, a customized Ink-jet and screen printing systems, coupled with customized substrate handling solution, customized printing algorithms, and a customized ink drying process, in combination with a purchased turn-key line, were used to complete the high efficiency solar cells. This development work delivered a process capable of high volume producing 18.5% efficient crystalline Silicon solar cells and enabled the Innovalight to commercialize its technology by the summer of 2010.

Silicon-micromachined microchannel plates

International Nuclear Information System (INIS)

Beetz, Charles P.; Boerstler, Robert; Steinbeck, John; Lemieux, Bryan; Winn, David R.

2000-01-01

Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of ∼0.5 to ∼25 μm, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposited or nucleated in the channels or the first strike surface. Results on resistivity, secondary emission and gain are presented

Removal of inclusions from silicon

Science.gov (United States)

Ciftja, Arjan; Engh, Thorvald Abel; Tangstad, Merete; Kvithyld, Anne; Øvrelid, Eivind Johannes

2009-11-01

The removal of inclusions from molten silicon is necessary to satisfy the purity requirements for solar grade silicon. This paper summarizes two methods that are investigated: (i) settling of the inclusions followed by subsequent directional solidification and (infiltration by ceramic foam filters. Settling of inclusions followed by directional solidification is of industrial importance for production of low-cost solar grade silicon. Filtration is reported as the most efficient method for removal of inclusions from the top-cut silicon scrap.

Silicon Tracking Upgrade at CDF

International Nuclear Information System (INIS)

Kruse, M.C.

1998-04-01

The Collider Detector at Fermilab (CDF) is scheduled to begin recording data from Run II of the Fermilab Tevatron in early 2000. The silicon tracking upgrade constitutes both the upgrade to the CDF silicon vertex detector (SVX II) and the new Intermediate Silicon Layers (ISL) located at radii just beyond the SVX II. Here we review the design and prototyping of all aspects of these detectors including mechanical design, data acquisition, and a trigger based on silicon tracking

Radiation Hardening of Silicon Detectors

CERN Multimedia

Leroy, C; Glaser, M

2002-01-01

%RD48 %title\\\\ \\\\Silicon detectors will be widely used in experiments at the CERN Large Hadron Collider where high radiation levels will cause significant bulk damage. In addition to increased leakage current and charge collection losses worsening the signal to noise, the induced radiation damage changes the effective doping concentration and represents the limiting factor to long term operation of silicon detectors. The objectives are to develop radiation hard silicon detectors that can operate beyond the limits of the present devices and that ensure guaranteed operation for the whole lifetime of the LHC experimental programme. Radiation induced defect modelling and experimental results show that the silicon radiation hardness depends on the atomic impurities present in the initial monocrystalline material.\\\\ \\\\ Float zone (FZ) silicon materials with addition of oxygen, carbon, nitrogen, germanium and tin were produced as well as epitaxial silicon materials with epilayers up to 200 $\\mu$m thickness. Their im...

Silicon Alloying On Aluminium Based Alloy Surface

International Nuclear Information System (INIS)

Suryanto

2002-01-01

Silicon alloying on surface of aluminium based alloy was carried out using electron beam. This is performed in order to enhance tribological properties of the alloy. Silicon is considered most important alloying element in aluminium alloy, particularly for tribological components. Prior to silicon alloying. aluminium substrate were painted with binder and silicon powder and dried in a furnace. Silicon alloying were carried out in a vacuum chamber. The Silicon alloyed materials were assessed using some techniques. The results show that silicon alloying formed a composite metal-non metal system in which silicon particles are dispersed in the alloyed layer. Silicon content in the alloyed layer is about 40% while in other place is only 10.5 %. The hardness of layer changes significantly. The wear properties of the alloying alloys increase. Silicon surface alloying also reduced the coefficient of friction for sliding against a hardened steel counter face, which could otherwise be higher because of the strong adhesion of aluminium to steel. The hardness of the silicon surface alloyed material dropped when it underwent a heating cycle similar to the ion coating process. Hence, silicon alloying is not a suitable choice for use as an intermediate layer for duplex treatment

Silicon microfabricated beam expander

Science.gov (United States)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-03-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Silicon germanium as a novel mask for silicon deep reactive ion etching

KAUST Repository

Serry, Mohamed Y.

2013-10-01

This paper reports on the use of p-type polycrystalline silicon germanium (poly-Si1-xGex) thin films as a new masking material for the cryogenic deep reactive ion etching (DRIE) of silicon. We investigated the etching behavior of various poly-Si1-xGex:B (0silicon, silicon oxide, and photoresist was determined at different etching temperatures, ICP and RF powers, and SF6 to O2 ratios. The study demonstrates that the etching selectivity of the SiGe mask for silicon depends strongly on three factors: Ge content; boron concentration; and etching temperature. Compared to conventional SiO2 and SiN masks, the proposed SiGe masking material exhibited several advantages, including high etching selectivity to silicon (>1:800). Furthermore, the SiGe mask was etched in SF6/O2 plasma at temperatures ≥ - 80°C and at rates exceeding 8 μm/min (i.e., more than 37 times faster than SiO2 or SiN masks). Because of the chemical and thermodynamic stability of the SiGe film as well as the electronic properties of the mask, it was possible to deposit the proposed film at CMOS backend compatible temperatures. The paper also confirms that the mask can easily be dry-removed after the process with high etching-rate by controlling the ICP and RF power and the SF6 to O2 ratios, and without affecting the underlying silicon substrate. Using low ICP and RF power, elevated temperatures (i.e., > - 80°C), and an adjusted O2:SF6 ratio (i.e., ~6%), we were able to etch away the SiGe mask without adversely affecting the final profile. Ultimately, we were able to develop deep silicon- trenches with high aspect ratio etching straight profiles. © 1992-2012 IEEE.

Array Automated Assembly Task Low Cost Silicon Solar Array Project. Phase 2. Annual technical report, September 20, 1977-December 31, 1978

Energy Technology Data Exchange (ETDEWEB)

Rhee, Sang S.; Jones, Gregory T.; Allison, Kimberly L.

1978-01-01

This program was conducted to develop and demonstrate those solar cells and module process steps which have the technological readiness or capability to achieve the 1986 LSA goals. Results are reported. Seventeen process groups were investigated. Very promising results were achieved. A laserscribe computer program was developed. It demonstrated that silicon solar cells could be trimmed and holed by laser without causing mechanical defects (i.e., microcracks) nor any major degradation in solar cell electrical performance. The silicon wafer surface preparation task demonstrated a low-cost, high throughput texturizing process readily adaptable to automation. Performance verification tests of a laser scanning system showed a limited capability to detect hidden cracks or defects in solar cells. A general review of currently available thick film printing equipment provided the indication that state-of-the-art technology can adequately transform the capability of current printing machines to the elevated rate of 7200 wafers per hour. The LFE System 8000 silicon nitride plasma deposition system with the inclusion of minor equipment modifications was shown to be consistent with the 1986 LSA pricing goals. The performance verification test of the silicon nitride A.R. coating process provided the result that texturized, A.R. coated solar cells display a 14.1% improvement in electrical performance over identical solar cells without an A.R. coating. A new electroless nickel plating system was installed and demonstrated a low-cost, high throughput process readily adaptable to automation. A multiple wafer dipping method was investigated and operational parameters defined. A flux removal method consisting of a three stage D.I. water cascade rinse system with ultrasonic agitator was found to be very promising. Also, a SAMICS cost analysis was performed. (WHK)

Structural modification of silicon during the formation process of porous silicon

International Nuclear Information System (INIS)

Martin-Palma, R.J.; Pascual, L.; Landa-Canovas, A.R.; Herrero, P.; Martinez-Duart, J.M.

2005-01-01

Direct examination of porous silicon (PS) by the use of high resolution transmission electron microscopy (HRTEM) allowed us to perform a deep insight into the formation mechanisms of this material. In particular, the structure of the PS/Si interface and that of the silicon nanocrystals that compose porous silicon were analyzed in detail. Furthermore, image processing was used to study in detail the structure of PS. The mechanism of PS formation and lattice matching between the PS layer and the Si substrate is analyzed and discussed. Finally, a formation mechanism for PS based on the experimental observations is proposed

Development of low cost silicon solar cells by reusing the silicon saw dust collected during wafering process

International Nuclear Information System (INIS)

Zaidi, Z.I.; Raza, B.; Ahmed, M.; Sheikh, H.; Qazi, I.A.

2002-01-01

Silicon material due to its abundance in nature and maximum conversion efficiency has been successfully being used for the fabrication of electronic and photovoltaic devices such as ICs, diodes, transistors and solar cells. The 80% of the semiconductor industry is ruled by silicon material. Single crystal silicon solar cells are in use for both space and terrestrial application, due to the well developed technology and better efficiency than polycrystalline and amorphous silicon solar cells. The current research work is an attempt to reduce the cost of single crystal silicon solar cells by reusing the silicon saw dust obtained during the watering process. During the watering process about 45% Si material is wasted in the form of Si powder dust. Various waste powder silicon samples were analyzed using inductively Coupled Plasma (ICP) technique, for metallic impurities critical for solar grade silicon material. The results were evaluated from impurity and cost point of view. (author)

Thin film silicon on silicon nitride for radiation hardened dielectrically isolated MISFET's

International Nuclear Information System (INIS)

Neamen, D.; Shedd, W.; Buchanan, B.

1975-01-01

The permanent ionizing radiation effects resulting from charge trapping in a silicon nitride isolation dielectric have been determined for a total ionizing dose up to 10 7 rads (Si). Junction FET's, whose active channel region is directly adjacent to the silicon-silicon nitride interface, were used to measure the effects of the radiation induced charge trapping in the Si 3 N 4 isolation dielectric. The JFET saturation current and channel conductance versus junction gate voltage and substrate voltage were characterized as a function of the total ionizing radiation dose. The experimental results on the Si 3 N 4 are compared to results on similar devices with SiO 2 dielectric isolation. The ramifications of using the silicon nitride for fabricating radiation hardened dielectrically isolated MIS devices are discussed

The silicon vertex tracker for star and future applications of silicon drift detectors

International Nuclear Information System (INIS)

Bellwied, Rene

2001-01-01

The Silicon Vertex Tracker (SVT) for the STAR experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory has recently been completed and installed. First data were taken in July 2001. The SVT is based on a novel semi-conductor technology called Silicon Drift Detectors. 216 large area (6 by 6 cm) Silicon wafers were employed to build a three barrel device capable of vertexing and tracking in a high occupancy environment. Its intrinsic radiation hardness, its operation at room temperature and its excellent position resolution (better than 20 micron) in two dimensions with a one dimensional detector readout, make this technology very robust and inexpensive and thus a viable alternative to CCD, Silicon pixel and Silicon strip detectors in a variety of applications from fundamental research in high-energy and nuclear physics to astrophysics to medical imaging. I will describe the development that led to the STAR-SVT, its performance and possible applications for the near future

Optoelectronic enhancement of monocrystalline silicon solar cells by porous silicon-assisted mechanical grooving

Energy Technology Data Exchange (ETDEWEB)

Ben Rabha, Mohamed; Mohamed, Seifeddine Belhadj; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

2011-03-15

One of the most important factors influencing silicon solar cells performances is the front side reflectivity. Consequently, new methods for efficient reduction of this reflectivity are searched. This has always been done by creating a rough surface that enables incident light of being absorbed within the solar cell. Combination of texturization-porous silicon surface treatment was found to be an attractive technical solution for lowering the reflectivity of monocrystalline silicon (c-Si). The texturization of the monocrystalline silicon wafer was carried out by means of mechanical grooving. A specific etching procedure was then applied to form a thin porous silicon layer enabling to remove mechanical damages. This simple and low cost method reduces the total reflectivity from 29% to 7% in the 300 - 950 nm wavelength range and enhances the diffusion length of the minority carriers from 100 {mu}m to 790 {mu}m (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The dark side of silicon energy efficient computing in the dark silicon era

CERN Document Server

Liljeberg, Pasi; Hemani, Ahmed; Jantsch, Axel; Tenhunen, Hannu

2017-01-01

This book presents the state-of-the art of one of the main concerns with microprocessors today, a phenomenon known as "dark silicon". Readers will learn how power constraints (both leakage and dynamic power) limit the extent to which large portions of a chip can be powered up at a given time, i.e. how much actual performance and functionality the microprocessor can provide. The authors describe their research toward the future of microprocessor development in the dark silicon era, covering a variety of important aspects of dark silicon-aware architectures including design, management, reliability, and test. Readers will benefit from specific recommendations for mitigating the dark silicon phenomenon, including energy-efficient, dedicated solutions and technologies to maximize the utilization and reliability of microprocessors. Enables readers to understand the dark silicon phenomenon and why it has emerged, including detailed analysis of its impacts; Presents state-of-the-art research, as well as tools for mi...

Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

KAUST Repository

Hussain, Muhammad Mustafa

2013-05-30

Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

KAUST Repository

Hussain, Muhammad Mustafa; Rojas, Jhonathan Prieto; Sevilla, Galo T.

2013-01-01

Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Colloidal characterization of silicon nitride and silicon carbide

Science.gov (United States)

Feke, Donald L.

1986-01-01

The colloidal behavior of aqueous ceramic slips strongly affects the forming and sintering behavior and the ultimate mechanical strength of the final ceramic product. The colloidal behavior of these materials, which is dominated by electrical interactions between the particles, is complex due to the strong interaction of the solids with the processing fluids. A surface titration methodology, modified to account for this interaction, was developed and used to provide fundamental insights into the interfacial chemistry of these systems. Various powder pretreatment strategies were explored to differentiate between true surface chemistry and artifacts due to exposure history. The colloidal behavior of both silicon nitride and carbide is dominated by silanol groups on the powder surfaces. However, the colloid chemistry of silicon nitride is apparently influenced by an additional amine group. With the proper powder treatments, silicon nitride and carbide powder can be made to appear colloidally equivalent. The impact of these results on processing control will be discussed.

Silicon-to-silicon wafer bonding using evaporated glass

DEFF Research Database (Denmark)

Weichel, Steen; Reus, Roger De; Lindahl, M.

1998-01-01

Anodic bending of silicon to silicon 4-in. wafers using an electron-beam evaporated glass (Schott 8329) was performed successfully in air at temperatures ranging from 200 degrees C to 450 degrees C. The composition of the deposited glass is enriched in sodium as compared to the target material....... The roughness of the as-deposited films was below 5 nm and was found to be unchanged by annealing at 500 degrees C for 1 h in air. No change in the macroscopic edge profiles of the glass film was found as a function of annealing; however, small extrusions appear when annealing above 450 degrees C. Annealing...... of silicon/glass structures in air around 340 degrees C for 15 min leads to stress-free structures. Bonded wafer pairs, however, show no reduction in stress and always exhibit compressive stress. The bond yield is larger than 95% for bonding temperatures around 350 degrees C and is above 80% for bonding...

Elite silicon and solar power

International Nuclear Information System (INIS)

Yasamanov, N.A.

2000-01-01

The article is of popular character, the following issues being considered: conversion of solar energy into electric one, solar batteries in space and on the Earth, growing of silicon large-size crystals, source material problems relating to silicon monocrystals production, outlooks of solar silicon batteries production [ru

Porous silicon: X-rays sensitivity

International Nuclear Information System (INIS)

Gerstenmayer, J.L.; Vibert, Patrick; Mercier, Patrick; Rayer, Claude; Hyvernage, Michel; Herino, Roland; Bsiesy, Ahmad

1994-01-01

We demonstrate that high porosity anodically porous silicon is radioluminescent. Interests of this study are double. Firstly: is the construction of porous silicon X-rays detectors (imagers) possible? Secondly: is it necessary to protect silicon porous based optoelectronic systems from ionising radiations effects (spatial environment)? ((orig.))

High-density oxidized porous silicon

International Nuclear Information System (INIS)

Gharbi, Ahmed; Souifi, Abdelkader; Remaki, Boudjemaa; Halimaoui, Aomar; Bensahel, Daniel

2012-01-01

We have studied oxidized porous silicon (OPS) properties using Fourier transform infraRed (FTIR) spectroscopy and capacitance–voltage C–V measurements. We report the first experimental determination of the optimum porosity allowing the elaboration of high-density OPS insulators. This is an important contribution to the research of thick integrated electrical insulators on porous silicon based on an optimized process ensuring dielectric quality (complete oxidation) and mechanical and chemical reliability (no residual pores or silicon crystallites). Through the measurement of the refractive indexes of the porous silicon (PS) layer before and after oxidation, one can determine the structural composition of the OPS material in silicon, air and silica. We have experimentally demonstrated that a porosity approaching 56% of the as-prepared PS layer is required to ensure a complete oxidation of PS without residual silicon crystallites and with minimum porosity. The effective dielectric constant values of OPS materials determined from capacitance–voltage C–V measurements are discussed and compared to FTIR results predictions. (paper)

Silicon spintronics with ferromagnetic tunnel devices

International Nuclear Information System (INIS)

Jansen, R; Sharma, S; Dash, S P; Min, B C

2012-01-01

In silicon spintronics, the unique qualities of ferromagnetic materials are combined with those of silicon, aiming at creating an alternative, energy-efficient information technology in which digital data are represented by the orientation of the electron spin. Here we review the cornerstones of silicon spintronics, namely the creation, detection and manipulation of spin polarization in silicon. Ferromagnetic tunnel contacts are the key elements and provide a robust and viable approach to induce and probe spins in silicon, at room temperature. We describe the basic physics of spin tunneling into silicon, the spin-transport devices, the materials aspects and engineering of the magnetic tunnel contacts, and discuss important quantities such as the magnitude of the spin accumulation and the spin lifetime in the silicon. We highlight key experimental achievements and recent progress in the development of a spin-based information technology. (topical review)

Study of double porous silicon surfaces for enhancement of silicon solar cell performance

Science.gov (United States)

Razali, N. S. M.; Rahim, A. F. A.; Radzali, R.; Mahmood, A.

2017-09-01

In this work, design and simulation of double porous silicon surfaces for enhancement of silicon solar cell is carried out. Both single and double porous structures are constructed by using TCAD ATHENA and TCAD DEVEDIT tools of the SILVACO software respectively. After the structures were created, I-V characteristics and spectral response of the solar cell were extracted using ATLAS device simulator. Finally, the performance of the simulated double porous solar cell is compared with the performance of both single porous and bulk-Si solar cell. The results showed that double porous silicon solar cell exhibited 1.8% efficiency compared to 1.3% and 1.2% for single porous silicon and bulk-Si solar cell.

Effects of selected casting methods on mechanical behaviour of Al-Mg-Si alloy

Directory of Open Access Journals (Sweden)

Henry Kayode TALABI

2014-11-01

Full Text Available This study investigated the effects of selected casting methods on mechanical behaviour of Al-Mg-Si alloy. The casting methods used was spin, sand and die casting, these were done with a view to determine which of the casting methods will produce the best properties. The pure aluminium scrap, magnesium and silicon were subjected to chemical analysis using spectrometric analyzer, thereafter the charge calculation to determine the amount needed to be charged into the furnace was properly worked out and charged into the crucible furnace from which as-cast aluminium was obtained. The mechanical properties of the casting produced were assessed by hardness and impact toughness test. The optical microscopy and experimental density and porosity were also investigated. From the results it was observed that magnesium and silicon were well dispersed in aluminium matrix of the spin casting. It was observed from visual examination after machining that there were minimal defects. It was also observed that out of the three casting methods, spin casting possesses the best mechanical properties (hardness and impact toughness.

All-solid-state supercapacitors on silicon using graphene from silicon carbide

Energy Technology Data Exchange (ETDEWEB)

Wang, Bei; Ahmed, Mohsin; Iacopi, Francesca, E-mail: f.iacopi@griffith.edu.au [Environmental Futures Research Institute, Griffith University, Nathan 4111 (Australia); Wood, Barry [Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia 4072 (Australia)

2016-05-02

Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 μF cm{sup −2} with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.

All-solid-state supercapacitors on silicon using graphene from silicon carbide

International Nuclear Information System (INIS)

Wang, Bei; Ahmed, Mohsin; Iacopi, Francesca; Wood, Barry

2016-01-01

Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 μF cm"−"2 with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.

Enhanced Raman scattering in porous silicon grating.

Science.gov (United States)

Wang, Jiajia; Jia, Zhenhong; Lv, Changwu

2018-03-19

The enhancement of Raman signal on monocrystalline silicon gratings with varying groove depths and on porous silicon grating were studied for a highly sensitive surface enhanced Raman scattering (SERS) response. In the experiment conducted, porous silicon gratings were fabricated. Silver nanoparticles (Ag NPs) were then deposited on the porous silicon grating to enhance the Raman signal of the detective objects. Results show that the enhancement of Raman signal on silicon grating improved when groove depth increased. The enhanced performance of Raman signal on porous silicon grating was also further improved. The Rhodamine SERS response based on Ag NPs/ porous silicon grating substrates was enhanced relative to the SERS response on Ag NPs/ porous silicon substrates. Ag NPs / porous silicon grating SERS substrate system achieved a highly sensitive SERS response due to the coupling of various Raman enhancement factors.

The Influence of Aluminum on the Microstructure and Hardness of Mg-5Si-7Sn Alloy

Directory of Open Access Journals (Sweden)

Rzychoń T.

2016-03-01

Full Text Available Magnesium alloys due the low density and good mechanical properties are mainly used in the automotive and aerospace industry. In recent years, magnesium alloys are extensively developed for use in high temperatures (above 120°C. Among these alloys, magnesium alloys containing tin and silicon have large possibilities of application due to the formation of thermally stable intermetallic Mg2Sn and Mg2Si. In this paper the influence of aluminum and heat treatment on the on the microstructure and hardness of Mg-7Sn-5Si alloy is reported. It was found that the microstructure of Mg-7Sn-5Si alloy consist of α-Mg solid solution, Mg2Sn and Mg2Si compounds. Addition of 2 wt% of Al to Mg-7Sn-5Si alloy causes the formation of Al2Sn phase. Moreover, Al dissolves in the α-Mg solid solution. The solution heat-treatment of tested alloys at 500°C for 24 h causes the dissolve the Mg2Sn phase in the α-Mg matrix and spheroidization of Mg2Si compound. The Mg2Si primary crystals are stable at solution temperature. After ageing treatment the precipitation process of equilibrium Mg2Sn phase was found in both alloys. The addition of aluminum has a positive effect on the hardness of Mg-7Sn-5Si alloy. In case of Mg-5Si-7Sn-2Al alloy the highest hardness was obtained for sample aged for 148 h at 250°C (88 HV2, while in case of Al-free alloy the highest hardness is 70 HV for material aged for 148 h at 250°C.

Photo-EMF Sensitivity of Porous Silicon Thin Layer–Crystalline Silicon Heterojunction to Ammonia Adsorption

Directory of Open Access Journals (Sweden)

Kae Dal Kwack

2011-01-01

Full Text Available A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.

Science.gov (United States)

Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

2011-01-01

A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

Photo-EMF Sensitivity of Porous Silicon Thin Layer–Crystalline Silicon Heterojunction to Ammonia Adsorption

Science.gov (United States)

Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

2011-01-01

A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light. PMID:22319353

Reduction of absorption loss in multicrystalline silicon via combination of mechanical grooving and porous silicon

Energy Technology Data Exchange (ETDEWEB)

Ben Rabha, Mohamed; Mohamed, Seifeddine Belhadj; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

2011-03-15

Surface texturing of silicon wafer is a key step to enhance light absorption and to improve the solar cell performances. While alkaline-texturing of single crystalline silicon wafers was well established, no efficient chemical solution has been successfully developed for multicrystalline silicon wafers. Thus, the use of alternative new methods for effective texturization of multicrystalline silicon is worth to be investigated. One of the promising texturing techniques of multicrystalline silicon wafers is the use of mechanical grooves. However, most often, physical damages occur during mechanical grooves of the wafer surface, which in turn require an additional step of wet processing-removal damage. Electrochemical surface treatment seems to be an adequate solution for removing mechanical damage throughout porous silicon formation. The topography of untreated and porous silicon-treated mechanically textured surface was investigated using scanning electron microscopy (SEM). As a result of the electrochemical surface treatment, the total reflectivity drops to about 5% in the 400-1000 nm wavelength range and the effective minority carrier diffusion length enhances from 190 {mu}m to about 230 {mu}m (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The Effectiveness of Al-Si Coatings for Preventing Interfacial Reaction in Al-Mg Dissimilar Metal Welding

Science.gov (United States)

Wang, Yin; Al-Zubaidy, Basem; Prangnell, Philip B.

2018-01-01

The dissimilar welding of aluminum to magnesium is challenging because of the rapid formation of brittle intermetallic compounds (IMC) at the weld interface. An Al-Si coating interlayer was selected to address this problem, based on thermodynamic calculations which predicted that silicon would change the reaction path to avoid formation of the normally observed binary Al-Mg IMC phases ( β-Al3Mg2 and γ-Al12Mg17). Long-term static heat treatments confirmed that a Si-rich coating will preferentially produce the Mg2Si phase in competition with the less stable, β-Al3Mg2 and γ-Al12Mg17 binary IMC phases, and this reduced the overall reaction layer thickness. However, when an Al-Si clad sheet was tested in a real welding scenario, using the Refill™ friction stir spot welding (FSSW) technique, Mg2Si was only produced in very small amounts owing to the much shorter reaction time. Surprisingly, the coating still led to a significant reduction in the IMC reaction layer thickness and the welds exhibited enhanced mechanical performance, with improved strength and fracture energy. This beneficial behavior has been attributed to the softer coating material both reducing the welding temperature and giving rise to the incorporation of Si particles into the reaction layer, which toughened the brittle interfacial IMC phases during crack propagation.

Laboratory course on silicon sensors

CERN Document Server

Crescio, E; Roe, S; Rudge, A

2003-01-01

The laboratory course consisted of four different mini sessions, in order to give the student some hands-on experience on various aspects of silicon sensors and related integrated electronics. The four experiments were. 1. Characterisation of silicon diodes for particle detection 2. Study of noise performance of the Viking readout circuit 3. Study of the position resolution of a silicon microstrip sensor 4. Study of charge transport in silicon with a fast amplifier The data in the following were obtained during the ICFA school by the students.

Lake Roosevelt Fisheries Evaluation Program; Limnological and Fisheries Monitoring, Annual Report 2000.

Energy Technology Data Exchange (ETDEWEB)

Lee, Chuck; Scofield, Ben; Pavlik, Deanne

2003-03-01

A slightly dryer than normal year yielded flows in Lake Roosevelt that were essentially equal to the past ten year average. Annual mean inflow and outflow were 3,160.3 m3/s and 3,063.4 m3/s respectively. Mean reservoir elevation was 387.2 m above sea level at the Grand Coulee Dam forebay. The forebay elevation was below the mean elevation for a total of 168 days. During the first half of the 2000 forebay elevation changed at a rate of 0.121 m/d and during the last half changed at a rate of 0.208 m/d. The higher rate of elevation change earlier in the year is due to the drawdown to accommodate spring runoff. Mean annual water retention time was 40 days. Annual mean total dissolved gas was 108%. Total dissolved gas was greatest at upriver locations (110% = US/Canada Border annual mean) and decreased moving toward Grand Coulee Dam (106% = Grand Coulee Dam Forebay annual mean). Total dissolved gas was greatest in May (122% reservoir wide monthly mean). Gas bubble trauma was observed in 16 fish primarily largescale suckers and was low in severity. Reservoir wide mean temperatures were greatest in August (19.5 C) and lowest in January (5.5 C). The Spokane River and Sanpoil River Arms experienced higher temperatures than the mainstem reservoir. Brief stratification was observed at the Sanpoil River shore location in July. Warm water temperatures in the Spokane Arm contributed to low dissolved oxygen concentrations in August (2.6 mg/L at 33 m). However, decomposition of summer algal biomass was likely the main cause of depressed dissolved oxygen concentrations. Otherwise, dissolved oxygen profiles were relatively uniform throughout the water column across other sampling locations. Annual mean Secchi depth throughout the reservoir was 5.7 m. Nutrient concentrations were generally low, however, annual mean total phosphorus (0.016 mg/L) was in the mesotrophic range. Annual mean total nitrogen was in the meso-oligotrophic range. Total nitrogen to total phosphorus ratios were

Application of hydrogen-plasma technology for property modification of silicon and producing the silicon-based structures

International Nuclear Information System (INIS)

Fedotov, A.K.; Mazanik, A.V.; Ul'yashin, A.G.; Dzhob, R; Farner, V.R.

2000-01-01

Effects of atomic hydrogen on the properties of Czochralski-grown single crystal silicon as well as polycrystalline shaped silicon have been investigated. It was established that the buried defect layers created by high-energy hydrogen or helium ion implantation act as a good getter centers for hydrogen atoms introduced in silicon in the process of hydrogen plasma hydrogenation. Atomic hydrogen was shown to be active as a catalyzer significantly enhancing the rate of thermal donors formation in p-type single crystal silicon. This effect can be used for n-p- and p-n-p-silicon based device structures producing [ru

Effect of Mg and Si co-substitution on microstructure and strength of tricalcium phosphate ceramics.

Science.gov (United States)

García-Páez, Ismael H; Carrodeguas, Raúl García; De Aza, Antonio H; Baudín, Carmen; Pena, Pilar

2014-02-01

Magnesium and silicon co-doped tricalcium phosphate (TCP) ceramics with compositions corresponding to 0, 5 and 10wt% CaMg(SiO3)2 in the system Ca3(PO4)2-CaMg(SiO3)2 were obtained by conventional sintering of compacted mixtures of Ca3(PO4)2, MgO, SiO2 and CaCO3 powders at temperatures between 1100 and 1450°C. Microstructural analyses were performed by X-ray diffraction and field emission scanning electron microscopy with energy dispersive spectroscopy. Major phases in the obtained ceramics were β- or α+β-tricalcium phosphate containing Mg and Si in solid solution. Certain amounts of liquid were formed during sintering depending on composition and temperature. There were found significant differences in distributions of strength determined by the diametral compression of disc tests (DCDT). Failure strengths were controlled by microstructural defects associated with phase development. Mg and Si additions were found to be effective to improve densification and associated strength of TCP bioceramics due to the enhancement of sintering by the low viscosity liquids formed. The highest density and strength were obtained for the TCP ceramic containing 5wt% CaMg(SiO3)2 sintered at 1300°C. Cracking and porosity increased at higher temperatures due to grain growth and swelling. © 2013 Published by Elsevier Ltd.

Silicon microfabricated beam expander

International Nuclear Information System (INIS)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-01-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed

Silicon microfabricated beam expander

Energy Technology Data Exchange (ETDEWEB)

Othman, A., E-mail: aliman@ppinang.uitm.edu.my; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A. [Faculty of Electrical Engineering, Universiti Teknologi MARA Malaysia, 40450, Shah Alam, Selangor (Malaysia); Ain, M. F. [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300,Nibong Tebal, Pulau Pinang (Malaysia)

2015-03-30

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Using silicon nanostructures for the improvement of silicon solar cells' efficiency

International Nuclear Information System (INIS)

Torre, J. de la; Bremond, G.; Lemiti, M.; Guillot, G.; Mur, P.; Buffet, N.

2006-01-01

Silicon nanostructures (ns-Si) show interesting optical and electrical properties as a result of the band gap widening caused by quantum confinement effects. Along with their potential utilization for silicon-based light emitters' fabrication, they could also represent an appealing option for the improvement of energy conversion efficiency in silicon-based solar cells whether by using their luminescence properties (photon down-conversion) or the excess photocurrent produced by an improved high-energy photon's absorption. In this work, we report on the morphological and optical studies of non-stoichiometric silica (SiO x ) and silicon nitride (SiN x ) layers containing silicon nanostructures (ns-Si) in view of their application for solar cell's efficiency improvement. The morphological studies of the samples performed by transmission electron microscopy (TEM) unambiguously show the presence of ns-Si in a crystalline form for high temperature-annealed SiO x layers and for low temperature deposition of SiN x layers. The photoluminescence emission (PL) shows a rather high efficiency in both kind of layers with an intensity of only a factor ∼ 100 lower than that of porous silicon (pi-Si). The photocurrent spectroscopy (PC) shows a significant increase of absorption at high photon energy excitation most probably related to photon absorption within ns-Si quantized states. Moreover, the absorption characteristics obtained from PC spectra show a good agreement with the PL emission states unambiguously demonstrating a same origin, related to Q-confined excitons within ns-Si. Finally, the major asset of this material is the possibility to incorporate it to solar cells manufacturing processing for an insignificant cost

Silicon processing for photovoltaics II

CERN Document Server

Khattak, CP

2012-01-01

The processing of semiconductor silicon for manufacturing low cost photovoltaic products has been a field of increasing activity over the past decade and a number of papers have been published in the technical literature. This volume presents comprehensive, in-depth reviews on some of the key technologies developed for processing silicon for photovoltaic applications. It is complementary to Volume 5 in this series and together they provide the only collection of reviews in silicon photovoltaics available.The volume contains papers on: the effect of introducing grain boundaries in silicon; the

Production of carrier-free 28Mg and 24Na by 50-180 MeV protons on Si, P, S, Cl, Ar and K. Excitation functions and chemical separation

International Nuclear Information System (INIS)

Lundqvist, H.; Malmborg, P.

1976-01-01

This work investigates the possible use of high energy proton bomardment of silicon, phosphorous, sulphur, chlorine, argon or potassium for production of carrier-free 28 Mg. A chemical separation is essential in this preparation in order to get rid of the bulk of target material and contaminating radionuclides. A simple and efficient method to get carrier-free 28 Mg with neglectible amounts of radio-chemical impurities has been established. (Auth.)

Photoluminescence of Mg{sub 2}Si films fabricated by magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Liao, Yang-Fang [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Xie, Quan, E-mail: qxie@gzu.edu.cn [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xiao, Qing-Quan [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Engineering Center for Avionics Electrical and Information Network of Guizhou Provincial Colleges and Universities, Anshun 561000 (China); Chen, Qian; Fan, Meng-Hui [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xie, Jing [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China)

2017-05-01

Highlights: • High quality Mg{sub 2}Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg{sub 2}Si films was reported. • The Mg{sub 2}Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg{sub 2}Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg{sub 2}Si-based light-emitting devices, Mg{sub 2}Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg{sub 2}Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg{sub 2}Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg{sub 2}Si film on Si (111) displays polycrystalline structure, whereas Mg{sub 2}Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg{sub 2}Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg{sub 2}Si films was observed for the first time. The PL emission wavelengths of Mg{sub 2}Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg{sub 2}Si films on glass substrate is much larger than that of Mg

Sol-gel synthesis of magnesium oxide-silicon dioxide glass compositions

Science.gov (United States)

Bansal, Narottam P.

1988-01-01

MgO-SiO2 glasses containing up to 15 mol pct MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol pct MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol pct MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol pct) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

Nano-ridge fabrication by local oxidation of silicon edges with silicon nitride as a mask

NARCIS (Netherlands)

Haneveld, J.; Berenschot, Johan W.; Maury, P.A.; Jansen, Henricus V.

2005-01-01

A method to fabricate nano-ridges over a full wafer is presented. The fabrication method uses local oxidation of silicon, with silicon nitride as a mask, and wet anisotropic etching of silicon. The realized structures are 7-20 nm wide, 40-100 nm high and centimeters long. All dimensions are easily

Silicon nanowire hybrid photovoltaics

KAUST Repository

Garnett, Erik C.

2010-06-01

Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

Silicon nanowire hybrid photovoltaics

KAUST Repository

Garnett, Erik C.; Peters, Craig; Brongersma, Mark; Cui, Yi; McGehee, Mike

2010-01-01

Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

Solutionizing temperature and abrasive wear behaviour of cast Al-Si-Mg alloys

International Nuclear Information System (INIS)

Sharma, Rajesh; Anesh; Dwivedi, D.K.

2007-01-01

In the present paper, the influence of solutionizing temperature during artificial age hardening treatment (T 6 ) of cast Al-(8, 12, 16%)Si-0.3%Mg on abrasive wear behaviour has been reported. Alloys were prepared by controlled melting and casting. Cast alloys were given artificial age hardening treatment having a sequence of solutionizing, quenching and artificial aging. All the alloys were solutionized at 450 deg. C, 480 deg. C, 510 deg. C, and 550 deg. C for 8 h followed by water quenching (30 deg. C) and aging hardening at 170 deg. C for 12 h. Abrasive wear tests were conducted against 320 grade SiC polishing papers at 5 N and 10 N normal loads. It was observed that the silicon content and solution temperature affected the wear resistance significantly. Increase in solution temperature improved the wear resistance. Hypereutectic alloy showed better wear resistance than the eutectic and hypoeutectic alloys under identical conditions. Optical microstructure study of alloys revealed that the increase in solutionizing temperature improved distribution of silicon grains. Scanning electron microscopy (SEM) of wear surface was carried out to analyze the wear mechanism

Design and Fabrication of Silicon-on-Silicon-Carbide Substrates and Power Devices for Space Applications

Directory of Open Access Journals (Sweden)

Gammon P.M.

2017-01-01

Full Text Available A new generation of power electronic semiconductor devices are being developed for the benefit of space and terrestrial harsh-environment applications. 200-600 V lateral transistors and diodes are being fabricated in a thin layer of silicon (Si wafer bonded to silicon carbide (SiC. This novel silicon-on-silicon-carbide (Si/SiC substrate solution promises to combine the benefits of silicon-on-insulator (SOI technology (i.e device confinement, radiation tolerance, high and low temperature performance with that of SiC (i.e. high thermal conductivity, radiation hardness, high temperature performance. Details of a process are given that produces thin films of silicon 1, 2 and 5 μm thick on semi-insulating 4H-SiC. Simulations of the hybrid Si/SiC substrate show that the high thermal conductivity of the SiC offers a junction-to-case temperature ca. 4× less that an equivalent SOI device; reducing the effects of self-heating, and allowing much greater power density. Extensive electrical simulations are used to optimise a 600 V laterally diffused metal-oxide-semiconductor field-effect transistor (LDMOSFET implemented entirely within the silicon thin film, and highlight the differences between Si/SiC and SOI solutions.

Silicon oxide nanoimprint stamp fabrication by edge lithography reinforced with silicon nitride

NARCIS (Netherlands)

Zhao, Yiping; Berenschot, Johan W.; de Boer, Meint J.; Jansen, Henricus V.; Tas, Niels Roelof; Huskens, Jurriaan; Elwenspoek, Michael Curt

2007-01-01

The fabrication of silicon oxide nanoimprint stamp employing edge lithography in combination with silicon nitride deposition is presented. The fabrication process is based on conventional photolithography an weg etching methods. Nanoridges with width dimension of sub-20 nm were fabricated by edge

Amorphous silicon rich silicon nitride optical waveguides for high density integrated optics

DEFF Research Database (Denmark)

Philipp, Hugh T.; Andersen, Karin Nordström; Svendsen, Winnie Edith

2004-01-01

Amorphous silicon rich silicon nitride optical waveguides clad in silica are presented as a high-index contrast platform for high density integrated optics. Performance of different cross-sectional geometries have been measured and are presented with regards to bending loss and insertion loss...

Process for forming a porous silicon member in a crystalline silicon member

Science.gov (United States)

Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.

1999-01-01

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

Annual Carbon Emissions from Deforestation in the Amazon Basin between 2000 and 2010.

Science.gov (United States)

Song, Xiao-Peng; Huang, Chengquan; Saatchi, Sassan S; Hansen, Matthew C; Townshend, John R

2015-01-01

Reducing emissions from deforestation and forest degradation (REDD+) is considered one of the most cost-effective strategies for mitigating climate change. However, historical deforestation and emission rates-critical inputs for setting reference emission levels for REDD+-are poorly understood. Here we use multi-source, time-series satellite data to quantify carbon emissions from deforestation in the Amazon basin on a year-to-year basis between 2000 and 2010. We first derive annual deforestation indicators by using the Moderate Resolution Imaging Spectroradiometer Vegetation Continuous Fields (MODIS VCF) product. MODIS indicators are calibrated by using a large sample of Landsat data to generate accurate deforestation rates, which are subsequently combined with a spatially explicit biomass dataset to calculate committed annual carbon emissions. Across the study area, the average deforestation and associated carbon emissions were estimated to be 1.59 ± 0.25 M ha•yr(-1) and 0.18 ± 0.07 Pg C•yr(-1) respectively, with substantially different trends and inter-annual variability in different regions. Deforestation in the Brazilian Amazon increased between 2001 and 2004 and declined substantially afterwards, whereas deforestation in the Bolivian Amazon, the Colombian Amazon, and the Peruvian Amazon increased over the study period. The average carbon density of lost forests after 2005 was 130 Mg C•ha(-1), ~11% lower than the average carbon density of remaining forests in year 2010 (144 Mg C•ha(-1)). Moreover, the average carbon density of cleared forests increased at a rate of 7 Mg C•ha(-1)•yr(-1) from 2005 to 2010, suggesting that deforestation has been progressively encroaching into high-biomass lands in the Amazon basin. Spatially explicit, annual deforestation and emission estimates like the ones derived in this study are useful for setting baselines for REDD+ and other emission mitigation programs, and for evaluating the performance of such efforts.

Hybrid Integrated Platforms for Silicon Photonics

Science.gov (United States)

Liang, Di; Roelkens, Gunther; Baets, Roel; Bowers, John E.

2010-01-01

A review of recent progress in hybrid integrated platforms for silicon photonics is presented. Integration of III-V semiconductors onto silicon-on-insulator substrates based on two different bonding techniques is compared, one comprising only inorganic materials, the other technique using an organic bonding agent. Issues such as bonding process and mechanism, bonding strength, uniformity, wafer surface requirement, and stress distribution are studied in detail. The application in silicon photonics to realize high-performance active and passive photonic devices on low-cost silicon wafers is discussed. Hybrid integration is believed to be a promising technology in a variety of applications of silicon photonics.

Ultrafast Terahertz Conductivity of Photoexcited Nanocrystalline Silicon

DEFF Research Database (Denmark)

Cooke, David; MacDonald, A. Nicole; Hryciw, Aaron

2007-01-01

The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described by a class...... in the silicon nanocrystal films is dominated by trapping at the Si/SiO2 interface states, occurring on a 1–100 ps time scale depending on particle size and hydrogen passivation......The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described...

Epitaxial growth of silicon for layer transfer

Science.gov (United States)

Teplin, Charles; Branz, Howard M

2015-03-24

Methods of preparing a thin crystalline silicon film for transfer and devices utilizing a transferred crystalline silicon film are disclosed. The methods include preparing a silicon growth substrate which has an interface defining substance associated with an exterior surface. The methods further include depositing an epitaxial layer of silicon on the silicon growth substrate at the surface and separating the epitaxial layer from the substrate substantially along the plane or other surface defined by the interface defining substance. The epitaxial layer may be utilized as a thin film of crystalline silicon in any type of semiconductor device which requires a crystalline silicon layer. In use, the epitaxial transfer layer may be associated with a secondary substrate.

Silicon nanowire-based solar cells

Energy Technology Data Exchange (ETDEWEB)

Stelzner, Th; Pietsch, M; Andrae, G; Falk, F; Ose, E; Christiansen, S [Institute of Photonic Technology, Albert-Einstein-Strasse 9, D-07745 Jena (Germany)], E-mail: thomas.stelzner@ipht-jena.de

2008-07-23

The fabrication of silicon nanowire-based solar cells on silicon wafers and on multicrystalline silicon thin films on glass is described. The nanowires show a strong broadband optical absorption, which makes them an interesting candidate to serve as an absorber in solar cells. The operation of a solar cell is demonstrated with n-doped nanowires grown on a p-doped silicon wafer. From a partially illuminated area of 0.6 cm{sup 2} open-circuit voltages in the range of 230-280 mV and a short-circuit current density of 2 mA cm{sup -2} were obtained.

Silicon nanowire-based solar cells

International Nuclear Information System (INIS)

Stelzner, Th; Pietsch, M; Andrae, G; Falk, F; Ose, E; Christiansen, S

2008-01-01

The fabrication of silicon nanowire-based solar cells on silicon wafers and on multicrystalline silicon thin films on glass is described. The nanowires show a strong broadband optical absorption, which makes them an interesting candidate to serve as an absorber in solar cells. The operation of a solar cell is demonstrated with n-doped nanowires grown on a p-doped silicon wafer. From a partially illuminated area of 0.6 cm 2 open-circuit voltages in the range of 230-280 mV and a short-circuit current density of 2 mA cm -2 were obtained

Silicon Qubits

Energy Technology Data Exchange (ETDEWEB)

Ladd, Thaddeus D. [HRL Laboratories, LLC, Malibu, CA (United States); Carroll, Malcolm S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2018-02-28

Silicon is a promising material candidate for qubits due to the combination of worldwide infrastructure in silicon microelectronics fabrication and the capability to drastically reduce decohering noise channels via chemical purification and isotopic enhancement. However, a variety of challenges in fabrication, control, and measurement leaves unclear the best strategy for fully realizing this material’s future potential. In this article, we survey three basic qubit types: those based on substitutional donors, on metal-oxide-semiconductor (MOS) structures, and on Si/SiGe heterostructures. We also discuss the multiple schema used to define and control Si qubits, which may exploit the manipulation and detection of a single electron charge, the state of a single electron spin, or the collective states of multiple spins. Far from being comprehensive, this article provides a brief orientation to the rapidly evolving field of silicon qubit technology and is intended as an approachable entry point for a researcher new to this field.

Study of Silicon Microstrip Detector Properties for the LHCb Silicon Tracker

CERN Document Server

Lois-Gómez, C; Vázquez-Regueiro, P

2006-01-01

The LHCb experiment, at present under construction at the Large Hadron Collider at CERN, has been designed to perform high-precision measurements of CP violating phenomena and rare decays in the B meson systems. The need of a good tracking performance and the high density of particles close to the beam pipe lead to the use of silicon microstrip detectors in a significant part of the LHCb tracking system. The Silicon Tracker (ST) will be built using p-on-n silicon detectors with strip pitches of approximately 200 $\\mu$m and readout strips up to 38 cm in length. This thesis describes the tests carried out on silicon microstrip detectors for the ST, starting from the characterization of different prototypes up to the final tests on the detectors that are being installed at CERN. The results can be divided in three main blocks. The first part comprises an exhaustive characterization of several prototype sensors selected as suitable candidates for the detector and was performed in order to decide some design param...

Apparatus for making molten silicon

Science.gov (United States)

Levin, Harry (Inventor)

1988-01-01

A reactor apparatus (10) adapted for continuously producing molten, solar grade purity elemental silicon by thermal reaction of a suitable precursor gas, such as silane (SiH.sub.4), is disclosed. The reactor apparatus (10) includes an elongated reactor body (32) having graphite or carbon walls which are heated to a temperature exceeding the melting temperature of silicon. The precursor gas enters the reactor body (32) through an efficiently cooled inlet tube assembly (22) and a relatively thin carbon or graphite septum (44). The septum (44), being in contact on one side with the cooled inlet (22) and the heated interior of the reactor (32) on the other side, provides a sharp temperature gradient for the precursor gas entering the reactor (32) and renders the operation of the inlet tube assembly (22) substantially free of clogging. The precursor gas flows in the reactor (32) in a substantially smooth, substantially axial manner. Liquid silicon formed in the initial stages of the thermal reaction reacts with the graphite or carbon walls to provide a silicon carbide coating on the walls. The silicon carbide coated reactor is highly adapted for prolonged use for production of highly pure solar grade silicon. Liquid silicon (20) produced in the reactor apparatus (10) may be used directly in a Czochralski or other crystal shaping equipment.

Hole Injection at the Silicon/Aqueous Electrolyte Interface: A Possible Mechanism for Chemiluminescence from Porous Silicon

NARCIS (Netherlands)

Kooij, Ernst S.; Butter, K.; Kelly, J.J.

1998-01-01

The reduction mechanism of oxidizing agents at silicon and porous silicon electrodes has been investigated in relation to light emission from the porous semiconductor. Oxidizing agents with a positive redox potential are shown to inject holes into HF-pretreated silicon. However, as the degree of

Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications

International Nuclear Information System (INIS)

Akhter, Perveen; Huang, Mengbing; Spratt, William; Kadakia, Nirag; Amir, Faisal

2015-01-01

Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics

Advances in silicon nanophotonics

DEFF Research Database (Denmark)

Hvam, Jørn Märcher; Pu, Minhao

Silicon has long been established as an ideal material for passive integrated optical circuitry due to its high refractive index, with corresponding strong optical confinement ability, and its low-cost CMOS-compatible manufacturability. However, the inversion symmetry of the silicon crystal lattice.......g. in high-bit-rate optical communication circuits and networks, it is vital that the nonlinear optical effects of silicon are being strongly enhanced. This can among others be achieved in photonic-crystal slow-light waveguides and in nano-engineered photonic-wires (Fig. 1). In this talk I shall present some...... recent advances in this direction. The efficient coupling of light between optical fibers and the planar silicon devices and circuits is of crucial importance. Both end-coupling (Fig. 1) and grating-coupling solutions will be discussed along with polarization issues. A new scheme for a hybrid III...

Phosphorus-doped Amorphous Silicon Nitride Films Applied to Crystalline Silicon Solar Cells

NARCIS (Netherlands)

Feinäugle, Matthias

2008-01-01

The Photovoltaics Group at the Universitat Politècnica de Catalunya is investigating silicon carbide (SiC) for the electronic passivation of the surface of crystalline silicon solar cells. The doping of SiC passivation layers with phosphorus resulted in a clear improvement of the minority carrier

Synthesis of Novel Reactive Disperse Silicon-Containing Dyes and Their Coloring Properties on Silicone Rubbers

Directory of Open Access Journals (Sweden)

Ning Yu

2018-01-01

Full Text Available Novel red and purple reactive disperse silicon-containing dyes were designed and synthesized using p-nitroaniline and 6-bromo-2,4-dinitro-aniline as diazonium components, the first condensation product of cyanuric chloride and 3-(N,N-diethylamino-aniline as coupling component, and 3-aminopropylmethoxydimethylsilane, 3-aminopropylmethyldimethoxysilane, and 3-aminopropyltrimethoxysilane as silicone reactive agents. These dyes were characterized by UV-Vis, 1H-NMR, FT-IR, and MS. The obtained reactive disperse silicon-containing dyes were used to color silicone rubbers and the color fastness of the dyes were evaluated. The dry/wet rubbing and washing fastnesses of these dyes all reached 4–5 grade and the sublimation fastness was also above 4 grade, indicating outstanding performance in terms of color fastness. Such colored silicone rubbers showed bright and rich colors without affecting its static mechanical properties.

"Silicon millefeuille": From a silicon wafer to multiple thin crystalline films in a single step

Science.gov (United States)

Hernández, David; Trifonov, Trifon; Garín, Moisés; Alcubilla, Ramon

2013-04-01

During the last years, many techniques have been developed to obtain thin crystalline films from commercial silicon ingots. Large market applications are foreseen in the photovoltaic field, where important cost reductions are predicted, and also in advanced microelectronics technologies as three-dimensional integration, system on foil, or silicon interposers [Dross et al., Prog. Photovoltaics 20, 770-784 (2012); R. Brendel, Thin Film Crystalline Silicon Solar Cells (Wiley-VCH, Weinheim, Germany 2003); J. N. Burghartz, Ultra-Thin Chip Technology and Applications (Springer Science + Business Media, NY, USA, 2010)]. Existing methods produce "one at a time" silicon layers, once one thin film is obtained, the complete process is repeated to obtain the next layer. Here, we describe a technology that, from a single crystalline silicon wafer, produces a large number of crystalline films with controlled thickness in a single technological step.

Silicon integrated circuit process

International Nuclear Information System (INIS)

Lee, Jong Duck

1985-12-01

This book introduces the process of silicon integrated circuit. It is composed of seven parts, which are oxidation process, diffusion process, ion implantation process such as ion implantation equipment, damage, annealing and influence on manufacture of integrated circuit and device, chemical vapor deposition process like silicon Epitaxy LPCVD and PECVD, photolithography process, including a sensitizer, spin, harden bake, reflection of light and problems related process, infrared light bake, wet-etch, dry etch, special etch and problems of etching, metal process like metal process like metal-silicon connection, aluminum process, credibility of aluminum and test process.

Silicon integrated circuit process

Energy Technology Data Exchange (ETDEWEB)

Lee, Jong Duck

1985-12-15

This book introduces the process of silicon integrated circuit. It is composed of seven parts, which are oxidation process, diffusion process, ion implantation process such as ion implantation equipment, damage, annealing and influence on manufacture of integrated circuit and device, chemical vapor deposition process like silicon Epitaxy LPCVD and PECVD, photolithography process, including a sensitizer, spin, harden bake, reflection of light and problems related process, infrared light bake, wet-etch, dry etch, special etch and problems of etching, metal process like metal process like metal-silicon connection, aluminum process, credibility of aluminum and test process.

Silicon micromachined vibrating gyroscopes

Science.gov (United States)

Voss, Ralf

1997-09-01

This work gives an overview of silicon micromachined vibrating gyroscopes. Market perspectives and fields of application are pointed out. The advantage of using silicon micromachining is discussed and estimations of the desired performance, especially for automobiles are given. The general principle of vibrating gyroscopes is explained. Vibrating silicon gyroscopes can be divided into seven classes. for each class the characteristic principle is presented and examples are given. Finally a specific sensor, based on a tuning fork for automotive applications with a sensitivity of 250(mu) V/degrees is described in detail.

Rapid age determination of oysters using LA-ICP-MS line scans of shell Mg/Ca ratios

Science.gov (United States)

Gillikin, D. P.; Durham, S. R.; Goodwin, D. H.

2016-02-01

Magnesium to calcium (Mg/Ca) ratios exhibit a strong temperature dependence in foraminifera and corals, but not in bivalve mollusks. Various studies have reported Mg/Ca-temperature relationships with R2 values ranging from 0.3 to 0.8 and significantly different relationships for bivalves growing at different salinities. However, this poor temperature correlation does not render Mg/Ca data useless. A weak temperature dependence would allow time (seasons and years) to be determined along the growth axis of shells. This would provide information about age, growth rate and also allow other proxies to be aligned with time. Typically, oxygen isotopes (δ18O) are used to age shells without clear periodic growth lines, which is time consuming and expensive. Line scans using laser ablation systems can cover several centimeters of shell in a few minutes. We test this method on the resilifer of two oyster species (Crassostrea gigas and C. virginica) using a 193 nm Laser-Ablation-ICP-MS. Living oysters were collected from San Francisco Bay, North Carolina, South Carolina, and the Gulf of Mexico; fossil shells (Pleistocene) were also collected in South Carolina. Shells were sampled for δ18O values and Mg/Ca ratios. We use annual cycles in δ18O values to confidently determine age, then apply the Mg/Ca technique. Shells of both species exhibit annual cyclicity in Mg/Ca ratios using spot and line scan laser sampling, which matche the seasonal cyclicity determined using δ18O values. Results show a good correlation between ages determined using the different methods. We conclude that LA-ICP-MS line scans offer a rapid and inexpensive technique for determining age, growth rate, and timing of shell growth in oyster reslifers.

Silicon containing copolymers

CERN Document Server

Amiri, Sahar; Amiri, Sanam

2014-01-01

Silicones have unique properties including thermal oxidative stability, low temperature flow, high compressibility, low surface tension, hydrophobicity and electric properties. These special properties have encouraged the exploration of alternative synthetic routes of well defined controlled microstructures of silicone copolymers, the subject of this Springer Brief. The authors explore the synthesis and characterization of notable block copolymers. Recent advances in controlled radical polymerization techniques leading to the facile synthesis of well-defined silicon based thermo reversible block copolymers?are described along with atom transfer radical polymerization (ATRP), a technique utilized to develop well-defined functional thermo reversible block copolymers. The brief also focuses on Polyrotaxanes and their great potential as stimulus-responsive materials which produce poly (dimethyl siloxane) (PDMS) based thermo reversible block copolymers.

Diamond deposition on siliconized stainless steel

International Nuclear Information System (INIS)

Alvarez, F.; Reinoso, M.; Huck, H.; Rosenbusch, M.

2010-01-01

Silicon diffusion layers in AISI 304 and AISI 316 type stainless steels were investigated as an alternative to surface barrier coatings for diamond film growth. Uniform 2 μm thick silicon rich interlayers were obtained by coating the surface of the steels with silicon and performing diffusion treatments at 800 deg. C. Adherent diamond films with low sp 2 carbon content were deposited on the diffused silicon layers by a modified hot filament assisted chemical vapor deposition (HFCVD) method. Characterization of as-siliconized layers and diamond coatings was performed by energy dispersive X-ray analysis, scanning electron microscopy, X-ray diffraction and Raman spectroscopy.

Transmutation doping of silicon solar cells

Science.gov (United States)

Wood, R. F.; Westbrook, R. D.; Young, R. T.; Cleland, J. W.

1977-01-01

Normal isotopic silicon contains 3.05% of Si-30 which transmutes to P-31 after thermal neutron absorption, with a half-life of 2.6 hours. This reaction is used to introduce extremely uniform concentrations of phosphorus into silicon, thus eliminating the areal and spatial inhomogeneities characteristic of chemical doping. Annealing of the lattice damage in the irradiated silicon does not alter the uniformity of dopant distribution. Transmutation doping also makes it possible to introduce phosphorus into polycrystalline silicon without segregation of the dopant at the grain boundaries. The use of neutron transmutation doped (NTD) silicon in solar cell research and development is discussed.

Hybrid Integrated Platforms for Silicon Photonics

Directory of Open Access Journals (Sweden)

John E. Bowers

2010-03-01

Full Text Available A review of recent progress in hybrid integrated platforms for silicon photonics is presented. Integration of III-V semiconductors onto silicon-on-insulator substrates based on two different bonding techniques is compared, one comprising only inorganic materials, the other technique using an organic bonding agent. Issues such as bonding process and mechanism, bonding strength, uniformity, wafer surface requirement, and stress distribution are studied in detail. The application in silicon photonics to realize high-performance active and passive photonic devices on low-cost silicon wafers is discussed. Hybrid integration is believed to be a promising technology in a variety of applications of silicon photonics.

Silicon on insulator self-aligned transistors

Science.gov (United States)

McCarthy, Anthony M.

2003-11-18

A method for fabricating thin-film single-crystal silicon-on-insulator (SOI) self-aligned transistors. Standard processing of silicon substrates is used to fabricate the transistors. Physical spaces, between the source and gate, and the drain and gate, introduced by etching the polysilicon gate material, are used to provide connecting implants (bridges) which allow the transistor to perform normally. After completion of the silicon substrate processing, the silicon wafer is bonded to an insulator (glass) substrate, and the silicon substrate is removed leaving the transistors on the insulator (glass) substrate. Transistors fabricated by this method may be utilized, for example, in flat panel displays, etc.

Creep analysis of silicone for podiatry applications.

Science.gov (United States)

Janeiro-Arocas, Julia; Tarrío-Saavedra, Javier; López-Beceiro, Jorge; Naya, Salvador; López-Canosa, Adrián; Heredia-García, Nicolás; Artiaga, Ramón

2016-10-01

This work shows an effective methodology to characterize the creep-recovery behavior of silicones before their application in podiatry. The aim is to characterize, model and compare the creep-recovery properties of different types of silicone used in podiatry orthotics. Creep-recovery phenomena of silicones used in podiatry orthotics is characterized by dynamic mechanical analysis (DMA). Silicones provided by Herbitas are compared by observing their viscoelastic properties by Functional Data Analysis (FDA) and nonlinear regression. The relationship between strain and time is modeled by fixed and mixed effects nonlinear regression to compare easily and intuitively podiatry silicones. Functional ANOVA and Kohlrausch-Willians-Watts (KWW) model with fixed and mixed effects allows us to compare different silicones observing the values of fitting parameters and their physical meaning. The differences between silicones are related to the variations of breadth of creep-recovery time distribution and instantaneous deformation-permanent strain. Nevertheless, the mean creep-relaxation time is the same for all the studied silicones. Silicones used in palliative orthoses have higher instantaneous deformation-permanent strain and narrower creep-recovery distribution. The proposed methodology based on DMA, FDA and nonlinear regression is an useful tool to characterize and choose the proper silicone for each podiatry application according to their viscoelastic properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Semiconducting silicon nanowires for biomedical applications

CERN Document Server

Coffer, JL

2014-01-01

Biomedical applications have benefited greatly from the increasing interest and research into semiconducting silicon nanowires. Semiconducting Silicon Nanowires for Biomedical Applications reviews the fabrication, properties, and applications of this emerging material. The book begins by reviewing the basics, as well as the growth, characterization, biocompatibility, and surface modification, of semiconducting silicon nanowires. It goes on to focus on silicon nanowires for tissue engineering and delivery applications, including cellular binding and internalization, orthopedic tissue scaffol

Synthesis of Silicon Nanocrystals in Microplasma Reactor

Science.gov (United States)

Nozaki, Tomohiro; Sasaki, Kenji; Ogino, Tomohisa; Asahi, Daisuke; Okazaki, Ken

Nanocrystalline silicon particles with a grain size of at least less than 10 nm are widely recognized as one of the key materials in optoelectronic devices, electrodes of lithium battery, bio-medical labels. There is also important character that silicon is safe material to the environment and easily gets involved in existing silicon technologies. To date, several synthesis methods such as sputtering, laser ablation, and plasma enhanced chemical vapor deposition (PECVD) based on low-pressure silane chemistry (SiH4) have been developed for precise control of size and density distributions of silicon nanocrystals. We explore the possibility of microplasma technologies for the efficient production of mono-dispersed nanocrystalline silicon particles in a micrometer-scale, continuous-flow plasma reactor operated at atmospheric pressure. Mixtures of argon, hydrogen, and silicon tetrachloride were activated using very high frequency (VHF = 144 MHz) power source in a capillary glass tube with a volume of less than 1 μ-liter. Fundamental plasma parameters of VHF capacitively coupled microplasma were characterized by optical emission spectroscopy, showing electron density of approximately 1015 cm-3 and rotational temperature of 1500 K, respectively. Such high-density non-thermal reactive plasma has a capability of decomposing silicon tetrachloride into atomic silicon to produce supersaturated atomic silicon vapor, followed by gas phase nucleation via three-body collision. The particle synthesis in high-density plasma media is beneficial for promoting nucleation process. In addition, further growth of silicon nuclei was able to be favorably terminated in a short-residence time reactor. Micro Raman scattering spectrum showed that as-deposited particles were mostly amorphous silicon with small fraction of silicon nanocrystals. Transmission electron micrograph confirmed individual silicon nanocrystals of 3-15 nm size. Although those particles were not mono-dispersed, they were

Amorphous silicon crystalline silicon heterojunction solar cells

CERN Document Server

Fahrner, Wolfgang Rainer

2013-01-01

Amorphous Silicon/Crystalline Silicon Solar Cells deals with some typical properties of heterojunction solar cells, such as their history, the properties and the challenges of the cells, some important measurement tools, some simulation programs and a brief survey of the state of the art, aiming to provide an initial framework in this field and serve as a ready reference for all those interested in the subject. This book helps to "fill in the blanks" on heterojunction solar cells. Readers will receive a comprehensive overview of the principles, structures, processing techniques and the current developmental states of the devices. Prof. Dr. Wolfgang R. Fahrner is a professor at the University of Hagen, Germany and Nanchang University, China.

Interaction of silicon nanoparticles with the molecules of bovine serum albumin in aqueous solutions

International Nuclear Information System (INIS)

Anenkova, K A; Sergeeva, I A; Petrova, G P; Fedorova, K V; Osminkina, L A; Timoshenko, Viktor Yu

2011-01-01

Using the method of photon-correlation spectroscopy, the coefficient of translational diffusion D t and the hydrodynamic radius R of the particles in aqueous solutions of the bovine serum albumin, containing silicon nanoparticles, are determined. The character of the dependence of these parameters on the concentration of the protein indicates the absence of interaction between the studied particles in the chosen range of albumin concentrations 0.2 - 1.0 mg mL -1 . (optical technologies in biophysics and medicine)

Broad range tuning of structural and optical properties of Znx Mg1−x O nanostructures grown by vapor transport method

International Nuclear Information System (INIS)

Vanjaria, Jignesh V; Azhar, Ebraheem Ali; Yu, Hongbin

2016-01-01

One-dimensional (1D) Zn x Mg 1−x O nanomaterials have drawn global attention due to their remarkable chemical and physical properties, and their diverse current and future technological applications. In this work, 1D ZnMgO nanostructures with different magnesium concentrations and different morphologies were grown directly on zinc oxide-coated silicon substrates by thermal evaporation of zinc oxide, magnesium boride and graphite powders. Highly well-defined Mg-rich ZnMgO nanorods with a rock salt structure and Zn-rich ZnMgO nanostructures with a wurtzite structure have been deposited individually by careful optimization of the source mixture and process parameters. Structural and optical properties of the deposited products were studied by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and Raman spectroscopy. Cathodoluminescence measurements demonstrate strong dominant peaks at 3.3 eV in Mg poor ZnMgO nanostructures and 4.8 eV in Mg rich nanostructures implying that the ZnMgO nanostructures can be used for the fabrication of deep UV optoelectronic devices. A mechanism for the formation and achieved diverse morphology of the ZnMgO nanostructures was proposed based on the characterization results. (paper)

Strained silicon as a new electro-optic material

DEFF Research Database (Denmark)

Jacobsen, Rune Shim; Andersen, Karin Nordström; Borel, Peter Ingo

2006-01-01

For decades, silicon has been the material of choice for mass fabrication of electronics. This is in contrast to photonics, where passive optical components in silicon have only recently been realized1, 2. The slow progress within silicon optoelectronics, where electronic and optical...... functionalities can be integrated into monolithic components based on the versatile silicon platform, is due to the limited active optical properties of silicon3. Recently, however, a continuous-wave Raman silicon laser was demonstrated4; if an effective modulator could also be realized in silicon, data...... processing and transmission could potentially be performed by all-silicon electronic and optical components. Here we have discovered that a significant linear electro-optic effect is induced in silicon by breaking the crystal symmetry. The symmetry is broken by depositing a straining layer on top...

Annual cycle of methane emission from a boreal fen measured by the eddy covariance technique

International Nuclear Information System (INIS)

Rinne, Janne.; Pihlatie, Mari; Haapanala, Sami; Vesala, Timo; Riutta, Terhi; Tuittila, Eeva-Stiina; Aurela, Mika; Tuovinen, Juha-Pekka

2007-01-01

The northern wetlands are one of the major sources of methane into the atmosphere. We measured annual methane emission from a boreal minerotrophic fen, Siikaneva, by the eddy covariance method. The average wintertime emissions were below 1 mg/m 2 /h, and the summertime emissions about 3.5 mg/m 2 /h. The water table depth did have any clear effect on methane emissions. During most of the year the emission depended on the temperature of peat below the water table. However, during the high and late summer the emission was independent on peat temperature as well. No diurnal cycle of methane flux was found. The total annual emission from the Siikaneva site was 12.6 g/m 2 . The emissions of the snow free period contributed 91% to the annual emission. The emission pulse during the snow melting period was clearly detectable but of minor importance adding only less than 3% to the annual emission. Over 20% of the carbon assimilated during the year as carbon dioxide was emitted as methane. Thus methane emission is an important component of the carbon balance of the Siikaneva fen. This indicates need of taking methane into account when studying carbon balances of northern fen ecosystems

23rd annual meeting of German Society for Neuroradiology

International Nuclear Information System (INIS)

Kuehne, D.

1987-01-01

Book of abstracts of this annual meeting summarizing the 58 lectures that dealt with the following subjects: Pathologic changes of the cervical vertebral canal and of the cervico-occipital region, as detected by modern imaging techniques (18 papers); diagnostic examination of the urbita and the middle cranial fossa (12 papers); invasive methods of neuroradiology (13 papers); 15 papers on freely chosen subjects. (MG) [de

Effect of Silicon Nanowire on Crystalline Silicon Solar Cell Characteristics

OpenAIRE

Zahra Ostadmahmoodi Do; Tahereh Fanaei Sheikholeslami; Hassan Azarkish

2016-01-01

Nanowires (NWs) are recently used in several sensor or actuator devices to improve their ordered characteristics. Silicon nanowire (Si NW) is one of the most attractive one-dimensional nanostructures semiconductors because of its unique electrical and optical properties. In this paper, silicon nanowire (Si NW), is synthesized and characterized for application in photovoltaic device. Si NWs are prepared using wet chemical etching method which is commonly used as a simple and low cost method fo...

Surface Effects in Segmented Silicon Sensors

OpenAIRE

Kopsalis, Ioannis

2017-01-01

Silicon detectors in Photon Science and Particle Physics require silicon sensors with very demanding specifications. New accelerators like the European X-ray Free Electron Laser (EuXFEL) and the High Luminosity upgrade of the Large Hadron Collider (HL-LHC), pose new challenges for silicon sensors, especially with respect to radiation hardness. High radiation doses and fluences damage the silicon crystal and the SiO2 layers at the surface, thus changing the sensor properties and limiting their...

Silicon photonics for multicore fiber communication

DEFF Research Database (Denmark)

Ding, Yunhong; Kamchevska, Valerija; Dalgaard, Kjeld

2016-01-01

We review our recent work on silicon photonics for multicore fiber communication, including multicore fiber fan-in/fan-out, multicore fiber switches towards reconfigurable optical add/drop multiplexers. We also present multicore fiber based quantum communication using silicon devices.......We review our recent work on silicon photonics for multicore fiber communication, including multicore fiber fan-in/fan-out, multicore fiber switches towards reconfigurable optical add/drop multiplexers. We also present multicore fiber based quantum communication using silicon devices....

Dephosphorization of Levitated Silicon-Iron Droplets for Production of Solar-Grade Silicon

Science.gov (United States)

Le, Katherine; Yang, Yindong; Barati, Mansoor; McLean, Alexander

2018-05-01

The treatment of relatively inexpensive silicon-iron alloys is a potential refining route in order to generate solar-grade silicon. Phosphorus is one of the more difficult impurity elements to remove by conventional processing. In this study, electromagnetic levitation was used to investigate phosphorus behavior in silicon-iron alloy droplets exposed to H2-Ar gas mixtures under various experimental conditions including, refining time, temperature (1723 K to 1993 K), gas flow rate, iron content, and initial phosphorus concentration in the alloy. Thermodynamic modeling of the dephosphorization reaction permitted prediction of the various gaseous products and indicated that diatomic phosphorus is the dominant species formed.

Signal development in irradiated silicon detectors

CERN Document Server

Kramberger, Gregor; Mikuz, Marko

2001-01-01

This work provides a detailed study of signal formation in silicon detectors, with the emphasis on detectors with high concentration of irradiation induced defects in the lattice. These defects give rise to deep energy levels in the band gap. As a consequence, the current induced by charge motion in silicon detectors is signifcantly altered. Within the framework of the study a new experimental method, Charge correction method, based on transient current technique (TCT) was proposed for determination of effective electron and hole trapping times in irradiated silicon detectors. Effective carrier trapping times were determined in numerous silicon pad detectors irradiated with neutrons, pions and protons. Studied detectors were fabricated on oxygenated and non-oxygenated silicon wafers with different bulk resistivities. Measured effective carrier trapping times were found to be inversely proportional to fuence and increase with temperature. No dependence on silicon resistivity and oxygen concentration was observ...

Development of advanced solid state radiation detectors: mercuric iodide and high gain silicon avalanche structures. Annual progress report, December 1, 1984-November 30, 1985

International Nuclear Information System (INIS)

Huth, G.C.; Dabrowski, A.J.

1986-04-01

This report covers the period from December 1984 through November 1985 for this research project sponsored by the Office of Health and Environmental Research of the Dept. of Energy. This work has two primary research objectives. The first is continuing development of the material mercuric iodide (HgI 2 ) and its applications to energy dispersive x-ray analysis and gamma ray spectrometry. The second task involves investigation of silicon ''avalanche'' (internal electron gain) radiation detector structures fabricated from new neutron transmutation doped (NTD) silicon single crystal

Ultra-fast silicon detectors

Energy Technology Data Exchange (ETDEWEB)

Sadrozinski, H. F.-W., E-mail: hartmut@scipp.ucsc.edu [Santa Cruz Institute for Particle Physics, UC Santa Cruz, Santa Cruz, CA 95064 (United States); Ely, S.; Fadeyev, V.; Galloway, Z.; Ngo, J.; Parker, C.; Petersen, B.; Seiden, A.; Zatserklyaniy, A. [Santa Cruz Institute for Particle Physics, UC Santa Cruz, Santa Cruz, CA 95064 (United States); Cartiglia, N.; Marchetto, F. [INFN Torino, Torino (Italy); Bruzzi, M.; Mori, R.; Scaringella, M.; Vinattieri, A. [University of Florence, Department of Physics and Astronomy, Sesto Fiorentino, Firenze (Italy)

2013-12-01

We propose to develop a fast, thin silicon sensor with gain capable to concurrently measure with high precision the space (∼10 μm) and time (∼10 ps) coordinates of a particle. This will open up new application of silicon detector systems in many fields. Our analysis of detector properties indicates that it is possible to improve the timing characteristics of silicon-based tracking sensors, which already have sufficient position resolution, to achieve four-dimensional high-precision measurements. The basic sensor characteristics and the expected performance are listed, the wide field of applications are mentioned and the required R and D topics are discussed. -- Highlights: •We are proposing thin pixel silicon sensors with 10's of picoseconds time resolution. •Fast charge collection is coupled with internal charge multiplication. •The truly 4-D sensors will revolutionize imaging and particle counting in many applications.

Relationship between silicon concentration and creatinine clearance

International Nuclear Information System (INIS)

Miura, Y.; Nakai, K.; Itoh, C.; Horikiri, J.; Sera, K.; Sato, M.

1998-01-01

Silicon levels in dialysis patients are markedly increasing. Using PIXE we determined the relationship between silicon concentration and creatinine clearance in 30 samples. Urine silicon concentration were significantly correlated to creatinine clearance (p<0.001). And also serum silicon concentration were significantly correlated to creatinine clearance (p<0.0001). (author)

Synthesis and In Vitro Activity Assessment of Novel Silicon Oxycarbide-Based Bioactive Glasses

Directory of Open Access Journals (Sweden)

Isabel Gonzalo-Juan

2016-11-01

Full Text Available Novel bioactive glasses based on a Ca- and Mg-modified silicon oxycarbide (SiCaMgOC were prepared from a polymeric single-source precursor, and their in vitro activity towards hydroxyapatite mineralization was investigated upon incubating the samples in simulated body fluid (SBF at 37 °C. The as-prepared materials exhibit an outstanding resistance against devitrification processes and maintain their amorphous nature even after exposure to 1300 °C. The X-ray diffraction (XRD analysis of the SiCaMgOC samples after the SBF test showed characteristic reflections of apatite after only three days, indicating a promising bioactivity. The release kinetics of the Ca2+ and Mg2+ and the adsorption of H+ after immersion of SiCaMgOC in simulated body fluid for different soaking times were analyzed via optical emission spectroscopy. The results show that the mechanism of formation of apatite on the surface of the SiCaMgOC powders is similar to that observed for standard (silicate bioactive glasses. A preliminary cytotoxicity investigation of the SiOC-based bioactive glasses was performed in the presence of mouse embryonic fibroblasts (MEF as well as human embryonic kidney cells (HEK-293. Due to their excellent high-temperature crystallization resistance in addition to bioactivity, the Ca- and Mg-modified SiOC glasses presented here might have high potential in applications related to bone repair and regeneration.

Highly efficient silicon light emitting diode

NARCIS (Netherlands)

Le Minh, P.; Holleman, J.; Wallinga, Hans

2002-01-01

In this paper, we describe the fabrication, using standard silicon processing techniques, of silicon light-emitting diodes (LED) that efficiently emit photons with energy around the silicon bandgap. The improved efficiency had been explained by the spatial confinement of charge carriers due to a

Silicon-Based Nanoscale Composite Energetic Materials

Science.gov (United States)

2013-02-01

1193-1211. 9. Krishnamohan, G., E.M. Kurian, and H.R. Rao, Thermal Analysis and Inverse Burning Rate Studies on Silicon-Potassium Nitrate System...reported in a journal paper and appears in the Appendix. Multiscale Nanoporous Silicon Combustion Introduction for nanoporous silicon effort While

Study of the 28Si(n,α)25Mg induced by 14,55 MeV neutrons

International Nuclear Information System (INIS)

Devillers, D.

1963-02-01

The aim of this work is the study of the 28 Si(n,α) 25 Mg nuclear reaction. The silicon target is in fact a p-n junction detector that is placed in a neutron beam produced thanks to the D-T reaction by 150 kv electrostatic accelerator. The impulses due to the alpha particles generated by the neutrons inside the junction are analysed with adequate electronic equipment. Protons are generated in other nuclear reactions, they have the same energy as the alpha particles, most of them are not contained in the junction but all contribute to the experimental spectra. In order to make the discrimination between alpha and protons efficient, the thickness of the junction must be in the same magnitude as the alpha particle range in the junction. Edge effects are likely to disturb emission spectra. Corrections are necessary but they require a fine knowledge of the physics of junctions. In the first chapter we review the different reactions that are induced by neutrons in silicon. The second chapter deals with the experimental conditions concerning the studies of the junction detector and of the 28 Si(n,α) 25 Mg reaction itself. The determination of the cross-section requires to know the incident neutron flux accurately, we have applied the method of the associated particle and we have calibrated a scintillation counter operating with an anthracene crystal to measure the neutron flux. The third chapter gathers all the calculations concerning the edge effects in the junction detector. In the fourth chapter we present the experimental results with and without taking into account the edge effects. We have measured the values of the cross-sections corresponding to the first 6 excited states of 25 Mg

An FPGA-based silicon neuronal network with selectable excitability silicon neurons

Directory of Open Access Journals (Sweden)

Jing eLi

2012-12-01

Full Text Available This paper presents a digital silicon neuronal network which simulates the nerve system in creatures and has the ability to execute intelligent tasks, such as associative memory. Two essential elements, the mathematical-structure-based digital spiking silicon neuron (DSSN and the transmitter release based silicon synapse, allow the network to show rich dynamic behaviors and are computationally efficient for hardware implementation. We adopt mixed pipeline and parallel structure and shift operations to design a sufficient large and complex network without excessive hardware resource cost. The network with $256$ full-connected neurons is built on a Digilent Atlys board equipped with a Xilinx Spartan-6 LX45 FPGA. Besides, a memory control block and USB control block are designed to accomplish the task of data communication between the network and the host PC. This paper also describes the mechanism of associative memory performed in the silicon neuronal network. The network is capable of retrieving stored patterns if the inputs contain enough information of them. The retrieving probability increases with the similarity between the input and the stored pattern increasing. Synchronization of neurons is observed when the successful stored pattern retrieval occurs.

Charge trapping and carrier transport mechanism in silicon-rich silicon oxynitride

International Nuclear Information System (INIS)

Yu Zhenrui; Aceves, Mariano; Carrillo, Jesus; Lopez-Estopier, Rosa

2006-01-01

The charge-trapping and carrier transport properties of silicon-rich silicon oxynitride (SRO:N) were studied. The SRO:N films were deposited by low pressure chemical vapor deposition. Infrared (IR) and transmission electron microscopic (TEM) measurements were performed to characterize their structural properties. Capacitance versus voltage and current versus voltage measurements (I-V) were used to study the charge-trapping and carrier transport mechanism. IR and TEM measurements revealed the existence of Si nanodots in SRO:N films. I-V measurements revealed that there are two conduction regimes divided by a threshold voltage V T . When the applied voltage is smaller than V T , the current is dominated by the charge transfer between the SRO:N and substrate; and in this regime only dynamic charging/discharging of the SRO:N layer is observed. When the voltage is larger than V T , the current increases rapidly and is dominated by the Poole-Frenkel mechanism; and in this regime, large permanent trapped charge density is obtained. Nitrogen incorporation significantly reduced the silicon nanodots or defects near the SRO:N/Si interface. However, a significant increase of the density of silicon nanodot in the bulk of the SRO:N layer is obtained

Wet-Chemical Preparation of Silicon Tunnel Oxides for Transparent Passivated Contacts in Crystalline Silicon Solar Cells.

Science.gov (United States)

Köhler, Malte; Pomaska, Manuel; Lentz, Florian; Finger, Friedhelm; Rau, Uwe; Ding, Kaining

2018-05-02

Transparent passivated contacts (TPCs) using a wide band gap microcrystalline silicon carbide (μc-SiC:H(n)), silicon tunnel oxide (SiO 2 ) stack are an alternative to amorphous silicon-based contacts for the front side of silicon heterojunction solar cells. In a systematic study of the μc-SiC:H(n)/SiO 2 /c-Si contact, we investigated selected wet-chemical oxidation methods for the formation of ultrathin SiO 2 , in order to passivate the silicon surface while ensuring a low contact resistivity. By tuning the SiO 2 properties, implied open-circuit voltages of 714 mV and contact resistivities of 32 mΩ cm 2 were achieved using μc-SiC:H(n)/SiO 2 /c-Si as transparent passivated contacts.

Radiation resistant passivation of silicon solar cells

International Nuclear Information System (INIS)

Swanson, R.M.; Gan, J.Y.; Gruenbaum, P.E.

1991-01-01

This patent describes a silicon solar cell having improved stability when exposed to concentrated solar radiation. It comprises a body of silicon material having a major surface for receiving radiation, a plurality of p and n conductivity regions in the body for collecting electrons and holes created by impinging radiation, and a passivation layer on the major surface including a first layer of silicon oxide in contact with the body and a polycrystalline silicon layer on the first layer of silicon oxide

Floating Silicon Method

Energy Technology Data Exchange (ETDEWEB)

Kellerman, Peter

2013-12-21

The Floating Silicon Method (FSM) project at Applied Materials (formerly Varian Semiconductor Equipment Associates), has been funded, in part, by the DOE under a “Photovoltaic Supply Chain and Cross Cutting Technologies” grant (number DE-EE0000595) for the past four years. The original intent of the project was to develop the FSM process from concept to a commercially viable tool. This new manufacturing equipment would support the photovoltaic industry in following ways: eliminate kerf losses and the consumable costs associated with wafer sawing, allow optimal photovoltaic efficiency by producing high-quality silicon sheets, reduce the cost of assembling photovoltaic modules by creating large-area silicon cells which are free of micro-cracks, and would be a drop-in replacement in existing high efficiency cell production process thereby allowing rapid fan-out into the industry.

Silicon photonics for telecommunications and biomedicine

CERN Document Server

Fathpour, Sasan

2011-01-01

Given silicon's versatile material properties, use of low-cost silicon photonics continues to move beyond light-speed data transmission through fiber-optic cables and computer chips. Its application has also evolved from the device to the integrated-system level. A timely overview of this impressive growth, Silicon Photonics for Telecommunications and Biomedicine summarizes state-of-the-art developments in a wide range of areas, including optical communications, wireless technologies, and biomedical applications of silicon photonics. With contributions from world experts, this reference guides

Spiral silicon drift detectors

International Nuclear Information System (INIS)

Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Lutz, G.; Kemmer, J.; Prechtel, U.; Ziemann, T.

1988-01-01

An advanced large area silicon photodiode (and x-ray detector), called Spiral Drift Detector, was designed, produced and tested. The Spiral Detector belongs to the family of silicon drift detectors and is an improvement of the well known Cylindrical Drift Detector. In both detectors, signal electrons created in silicon by fast charged particles or photons are drifting toward a practically point-like collection anode. The capacitance of the anode is therefore kept at the minimum (0.1pF). The concentric rings of the cylindrical detector are replaced by a continuous spiral in the new detector. The spiral geometry detector design leads to a decrease of the detector leakage current. In the spiral detector all electrons generated at the silicon-silicon oxide interface are collected on a guard sink rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease of the leakage current and the very small capacities of the detector anode with a capacitively matched preamplifier may improve the energy resolution of Spiral Drift Detectors operating at room temperature down to about 50 electrons rms. This resolution is in the range attainable at present only by cooled semiconductor detectors. 5 refs., 10 figs

Scattering characteristics from porous silicon

Directory of Open Access Journals (Sweden)

R. Sabet-Dariani

2000-12-01

Full Text Available   Porous silicon (PS layers come into existance as a result of electrochemical anodization on silicon. Although a great deal of research has been done on the formation and optical properties of this material, the exact mechanism involved is not well-understood yet.   In this article, first, the optical properties of silicon and porous silicon are described. Then, previous research and the proposed models about reflection from PS and the origin of its photoluminescence are reveiwed. The reflecting and scattering, absorption and transmission of light from this material, are then investigated. These experiments include,different methods of PS sample preparation their photoluminescence, reflecting and scattering of light determining different characteristics with respect to Si bulk.

Engineering piezoresistivity using biaxially strained silicon

DEFF Research Database (Denmark)

Pedersen, Jesper Goor; Richter, Jacob; Brandbyge, Mads

2008-01-01

of the piezocoefficient on temperature and dopant density is altered qualitatively for strained silicon. In particular, we find that a vanishing temperature coefficient may result for silicon with grown-in biaxial tensile strain. These results suggest that strained silicon may be used to engineer the iezoresistivity...

ePIXfab - The silicon photonics platform

NARCIS (Netherlands)

Khanna, A.; Drissi, Y.; Dumon, P.; Baets, R.; Absil, P.; Pozo Torres, J.M.; Lo Cascio, D.M.R.; Fournier, M.; Fedeli, J.M.; Fulbert, L.; Zimmermann, L.; Tillack, B.; Aalto, T.; O'Brien, P.; Deptuck, D.; Xu, J.; Gale, D.

2013-01-01

ePIXfab-The European Silicon Photonics Support Center continues to provide state-of-the-art silicon photonics solutions to academia and industry for prototyping and research. ePIXfab is a consortium of EU research centers providing diverse expertise in the silicon photonics food chain, from training

Phase Diagram of Al-Ca-Mg-Si System and Its Application for the Design of Aluminum Alloys with High Magnesium Content

Directory of Open Access Journals (Sweden)

Nikolay A. Belov

2017-10-01

Full Text Available The phase transformations in the Al-Ca-Mg-Si system have been studied using thermodynamic calculations and experimental methods. We show that at 10% Magnesium (Mg, depending on the concentrations of calcium (Ca and silicon (Si, the following phases crystallize first (apart from the aluminum (Al solid solution: Al4Ca, Mg2Si, and Al2CaSi2. We have found that the major part of the calculated concentration range is covered by the region of the primary crystallization of the Al2CaSi2 phase. Regardless of the Ca and Si content, the solidification of the aluminum-magnesium alloys ends with the following nonvariant eutectic reaction: L → (Al + Al4Ca + Mg2Si + Al3Mg2. With respect to the temperature and composition of the liquid phase, this reaction is close to the eutectic reaction in the Al-Mg binary system. The addition of Ca and Si to the Al-10% Mg base alloy increases its hardness, reduces its density, and has no negative influence on its corrosion resistance. We have also established that the near-eutectic alloy containing about 3% Ca and 1% Si has the optimum structure.

Hybrid III-V/silicon lasers

Science.gov (United States)

Kaspar, P.; Jany, C.; Le Liepvre, A.; Accard, A.; Lamponi, M.; Make, D.; Levaufre, G.; Girard, N.; Lelarge, F.; Shen, A.; Charbonnier, P.; Mallecot, F.; Duan, G.-H.; Gentner, J.-.; Fedeli, J.-M.; Olivier, S.; Descos, A.; Ben Bakir, B.; Messaoudene, S.; Bordel, D.; Malhouitre, S.; Kopp, C.; Menezo, S.

2014-05-01

The lack of potent integrated light emitters is one of the bottlenecks that have so far hindered the silicon photonics platform from revolutionizing the communication market. Photonic circuits with integrated light sources have the potential to address a wide range of applications from short-distance data communication to long-haul optical transmission. Notably, the integration of lasers would allow saving large assembly costs and reduce the footprint of optoelectronic products by combining photonic and microelectronic functionalities on a single chip. Since silicon and germanium-based sources are still in their infancy, hybrid approaches using III-V semiconductor materials are currently pursued by several research laboratories in academia as well as in industry. In this paper we review recent developments of hybrid III-V/silicon lasers and discuss the advantages and drawbacks of several integration schemes. The integration approach followed in our laboratory makes use of wafer-bonded III-V material on structured silicon-on-insulator substrates and is based on adiabatic mode transfers between silicon and III-V waveguides. We will highlight some of the most interesting results from devices such as wavelength-tunable lasers and AWG lasers. The good performance demonstrates that an efficient mode transfer can be achieved between III-V and silicon waveguides and encourages further research efforts in this direction.

X-ray and scanning electron microscopic investigation of porous silicon and silicon epitaxial layers grown on porous silicon

International Nuclear Information System (INIS)

Wierzchowski, W.; Pawlowska, M.; Nossarzewska-Orlowska, E.; Brzozowski, A.; Wieteska, K.; Graeff, W.

1998-01-01

The 1 to 5 μm thick layers of porous silicon and epitaxial layers grown on porous silicon were studied by means of X-ray diffraction methods, realised with a wide use of synchrotron source and scanning microscopy. The results of x-ray investigation pointed the difference of lateral periodicity between the porous layer and the substrate. It was also found that the deposition of epitaxial layer considerably reduced the coherence of porous fragments. A number of interface phenomena was also observed in section and plane wave topographs. The scanning electron microscopic investigation of cleavage faces enabled direct evaluation of porous layer thickness and revealed some details of their morphology. The scanning observation of etched surfaces of epitaxial layers deposited on porous silicon revealed dislocations and other defects not reasonable in the X-ray topographs. (author)

Influence of Chemical Composition and Structure in Silicon Dielectric Materials on Passivation of Thin Crystalline Silicon on Glass.

Science.gov (United States)

Calnan, Sonya; Gabriel, Onno; Rothert, Inga; Werth, Matteo; Ring, Sven; Stannowski, Bernd; Schlatmann, Rutger

2015-09-02

In this study, various silicon dielectric films, namely, a-SiOx:H, a-SiNx:H, and a-SiOxNy:H, grown by plasma enhanced chemical vapor deposition (PECVD) were evaluated for use as interlayers (ILs) between crystalline silicon and glass. Chemical bonding analysis using Fourier transform infrared spectroscopy showed that high values of oxidant gases (CO2 and/or N2), added to SiH4 during PECVD, reduced the Si-H and N-H bond density in the silicon dielectrics. Various three layer stacks combining the silicon dielectric materials were designed to minimize optical losses between silicon and glass in rear side contacted heterojunction pn test cells. The PECVD grown silicon dielectrics retained their functionality despite being subjected to harsh subsequent processing such as crystallization of the silicon at 1414 °C or above. High values of short circuit current density (Jsc; without additional hydrogen passivation) required a high density of Si-H bonds and for the nitrogen containing films, additionally, a high N-H bond density. Concurrently high values of both Jsc and open circuit voltage Voc were only observed when [Si-H] was equal to or exceeded [N-H]. Generally, Voc correlated with a high density of [Si-H] bonds in the silicon dielectric; otherwise, additional hydrogen passivation using an active plasma process was required. The highest Voc ∼ 560 mV, for a silicon acceptor concentration of about 10(16) cm(-3), was observed for stacks where an a-SiOxNy:H film was adjacent to the silicon. Regardless of the cell absorber thickness, field effect passivation of the buried silicon surface by the silicon dielectric was mandatory for efficient collection of carriers generated from short wavelength light (in the vicinity of the glass-Si interface). However, additional hydrogen passivation was obligatory for an increased diffusion length of the photogenerated carriers and thus Jsc in solar cells with thicker absorbers.

Method For Producing Mechanically Flexible Silicon Substrate

KAUST Repository

Hussain, Muhammad Mustafa

2014-08-28

A method for making a mechanically flexible silicon substrate is disclosed. In one embodiment, the method includes providing a silicon substrate. The method further includes forming a first etch stop layer in the silicon substrate and forming a second etch stop layer in the silicon substrate. The method also includes forming one or more trenches over the first etch stop layer and the second etch stop layer. The method further includes removing the silicon substrate between the first etch stop layer and the second etch stop layer.

Intermediate Bandgap Solar Cells From Nanostructured Silicon

Energy Technology Data Exchange (ETDEWEB)

Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

2014-10-30

This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

Method For Producing Mechanically Flexible Silicon Substrate

KAUST Repository

Hussain, Muhammad Mustafa; Rojas, Jhonathan Prieto

2014-01-01

A method for making a mechanically flexible silicon substrate is disclosed. In one embodiment, the method includes providing a silicon substrate. The method further includes forming a first etch stop layer in the silicon substrate and forming a second etch stop layer in the silicon substrate. The method also includes forming one or more trenches over the first etch stop layer and the second etch stop layer. The method further includes removing the silicon substrate between the first etch stop layer and the second etch stop layer.

Influence of Al grain structure on Fe bearing intermetallics during DC casting of an Al-Mg-Si alloy

OpenAIRE

Kumar, S.; O'Reilly, K.A.Q.

2016-01-01

207 mm diameter direct chill (DC) cast billets of 6063 aluminium-magnesium-silicon (Al-Mg-Si) alloy were produced with various different primary aluminium (α-Al) grain structures including feathery-dendrites, equiaxed-dendrites and equiaxed-globular morphologies. To control the α-Al grain structure (grain morphology and grain size) an intensive shearing melt conditioning technique and Al-5Ti-1B grain refiner were used. For the first time, due to the variety of controlled microstructures produ...

Optical characterization of nanocrystals in silicon rich oxide superlattices and porous silicon

International Nuclear Information System (INIS)

Agocs, E.; Petrik, P.; Milita, S.; Vanzetti, L.; Gardelis, S.; Nassiopoulou, A.G.; Pucker, G.; Balboni, R.; Fried, M.

2011-01-01

We propose to analyze ellipsometry data by using effective medium approximation (EMA) models. Thanks to EMA, having nanocrystalline reference dielectric functions and generalized critical point (GCP) model the physical parameters of two series of samples containing silicon nanocrystals, i.e. silicon rich oxide (SRO) superlattices and porous silicon layers (PSL), have been determined. The superlattices, consisting of ten SRO/SiO 2 layer pairs, have been prepared using plasma enhanced chemical vapor deposition. The porous silicon layers have been prepared using short monopulses of anodization current in the transition regime between porous silicon formation and electropolishing, in a mixture of hydrofluoric acid and ethanol. The optical modeling of both structures is similar. The effective dielectric function of the layer is calculated by EMA using nanocrystalline components (nc-Si and GCP) in a dielectric matrix (SRO) or voids (PSL). We discuss the two major problems occurring when modeling such structures: (1) the modeling of the vertically non-uniform layer structures (including the interface properties like nanoroughness at the layer boundaries) and (2) the parameterization of the dielectric function of nanocrystals. We used several techniques to reduce the large number of fit parameters of the GCP models. The obtained results are in good agreement with those obtained by X-ray diffraction and electron microscopy. We investigated the correlation of the broadening parameter and characteristic EMA components with the nanocrystal size and the sample preparation conditions, such as the annealing temperatures of the SRO superlattices and the anodization current density of the porous silicon samples. We found that the broadening parameter is a sensitive measure of the nanocrystallinity of the samples, even in cases, where the nanocrystals are too small to be visible for X-ray scattering. Major processes like sintering, phase separation, and intermixing have been

High performance multilayered nano-crystalline silicon/silicon-oxide light-emitting diodes on glass substrates

Energy Technology Data Exchange (ETDEWEB)

Darbari, S; Shahmohammadi, M; Mortazavi, M; Mohajerzadeh, S [Thin Film and Nano-Electronic Laboratory, School of ECE, University of Tehran, Tehran (Iran, Islamic Republic of); Abdi, Y [Nano-Physics Research Laboratory, Department of Physics, University of Tehran, Tehran (Iran, Islamic Republic of); Robertson, M; Morrison, T, E-mail: mohajer@ut.ac.ir [Department of Physics, Acadia University, Wolfville, NS (Canada)

2011-09-16

A low-temperature hydrogenation-assisted sequential deposition and crystallization technique is reported for the preparation of nano-scale silicon quantum dots suitable for light-emitting applications. Radio-frequency plasma-enhanced deposition was used to realize multiple layers of nano-crystalline silicon while reactive ion etching was employed to create nano-scale features. The physical characteristics of the films prepared using different plasma conditions were investigated using scanning electron microscopy, transmission electron microscopy, room temperature photoluminescence and infrared spectroscopy. The formation of multilayered structures improved the photon-emission properties as observed by photoluminescence and a thin layer of silicon oxy-nitride was then used for electrical isolation between adjacent silicon layers. The preparation of light-emitting diodes directly on glass substrates has been demonstrated and the electroluminescence spectrum has been measured.

High-efficient solar cells with porous silicon

International Nuclear Information System (INIS)

Migunova, A.A.

2002-01-01

It has been shown that the porous silicon is multifunctional high-efficient coating on silicon solar cells, modifies its surface and combines in it self antireflection and passivation properties., The different optoelectronic effects in solar cells with porous silicon were considered. The comparative parameters of uncovered photodetectors also solar cells with porous silicon and other coatings were resulted. (author)

Luminescence of porous silicon doped by erbium

International Nuclear Information System (INIS)

Bondarenko, V.P.; Vorozov, N.N.; Dolgij, L.N.; Dorofeev, A.M.; Kazyuchits, N.M.; Leshok, A.A.; Troyanova, G.N.

1996-01-01

The possibility of the 1.54 μm intensive luminescence in the silicon dense porous layers, doped by erbium, with various structures is shown. Low-porous materials of both porous type on the p-type silicon and porous silicon with wood-like structure on the n + type silicon may be used for formation of light-emitting structures

Process of preparing tritiated porous silicon

Science.gov (United States)

Tam, Shiu-Wing

1997-01-01

A process of preparing tritiated porous silicon in which porous silicon is equilibrated with a gaseous vapor containing HT/T.sub.2 gas in a diluent for a time sufficient for tritium in the gas phase to replace hydrogen present in the pore surfaces of the porous silicon.

Modification of silicon nitride and silicon carbide surfaces for food and biosensor applications

NARCIS (Netherlands)

Rosso, M.

2009-01-01

Silicon-rich silicon nitride (SixN4, x > 3) is a robust insulating material widely used for the coating of microdevices: its high chemical and mechanical inertness make it a material of choice for the reinforcement of fragile microstructures (e.g. suspended microcantilevers, micro-fabricated

Thin film silicon by a microwave plasma deposition technique: Growth and devices, and, interface effects in amorphous silicon/crystalline silicon solar cells

Science.gov (United States)

Jagannathan, Basanth

Thin film silicon (Si) was deposited by a microwave plasma CVD technique, employing double dilution of silane, for the growth of low hydrogen content Si films with a controllable microstructure on amorphous substrates at low temperatures (prepared by this technique. Such films showed a dark conductivity ˜10sp{-6} S/cm, with a conduction activation energy of 0.49 eV. Film growth and properties have been compared for deposition in Ar and He carrier systems and growth models have been proposed. Low temperature junction formation by undoped thin film silicon was examined through a thin film silicon/p-type crystalline silicon heterojunctions. The thin film silicon layers were deposited by rf glow discharge, dc magnetron sputtering and microwave plasma CVD. The hetero-interface was identified by current transport analysis and high frequency capacitance methods as the key parameter controlling the photovoltaic (PV) response. The effect of the interface on the device properties (PV, junction, and carrier transport) was examined with respect to modifications created by chemical treatment, type of plasma species, their energy and film microstructure interacting with the substrate. Thermally stimulated capacitance was used to determine the interfacial trap parameters. Plasma deposition of thin film silicon on chemically clean c-Si created electron trapping sites while hole traps were seen when a thin oxide was present at the interface. Under optimized conditions, a 10.6% efficient cell (11.5% with SiOsb2 A/R) with an open circuit voltage of 0.55 volts and a short circuit current density of 30 mA/cmsp2 was fabricated.

Amorphous silicon based particle detectors

OpenAIRE

Wyrsch, N.; Franco, A.; Riesen, Y.; Despeisse, M.; Dunand, S.; Powolny, F.; Jarron, P.; Ballif, C.

2012-01-01

Radiation hard monolithic particle sensors can be fabricated by a vertical integration of amorphous silicon particle sensors on top of CMOS readout chip. Two types of such particle sensors are presented here using either thick diodes or microchannel plates. The first type based on amorphous silicon diodes exhibits high spatial resolution due to the short lateral carrier collection. Combination of an amorphous silicon thick diode with microstrip detector geometries permits to achieve micromete...

Porous silicon: Synthesis and optical properties

International Nuclear Information System (INIS)

Naddaf, M.; Awad, F.

2006-01-01

Formation of porous silicon by electrochemical etching method of both p and n-type single crystal silicon wafers in HF based solutions has been performed by using three different modes. In addition to DC and pulsed voltage, a novel etching mode is developed to prepare light-emitting porous silicon by applying and holding-up a voltage in gradient steps form periodically, between the silicon wafer and a graphite electrode. Under same equivalent etching conditions, periodic gradient steps voltage etching can yield a porous silicon layer with stronger photoluminescence intensity and blue shift than the porous silicon layer prepared by DC or pulsed voltage etching. It has been found that the holding-up of the applied voltage during the etching process for defined interval of time is another significant future of this method, which highly affects the blue shift. This can be used for tailoring a porous layer with novel properties. The actual mechanism behind the blue shift is not clear exactly, even the experimental observation of atomic force microscope and purist measurements in support with quantum confinement model. It has been seen also from Fourier Transform Infrared study that interplays between O-Si-H and Si-H bond intensities play key role in deciding the efficiency of photoluminescence emission. Study of relative humidity sensing and photonic crystal properties of pours silicon samples has confirmed the advantages of the new adopted etching mode. The sensitivity at room temperature of porous silicon prepared by periodic gradient steps voltage etching was found to be about 70% as compared to 51% and 45% for the porous silicon prepared by DC and pulsed voltage etching, respectively. (author)

Porous silicon: Synthesis and optical properties

International Nuclear Information System (INIS)

Naddaf, M.; Awad, F.

2006-06-01

Formation of porous silicon by electrochemical etching method of both p and n-type single crystal silicon wafers in HF based solutions has been performed by using three different modes. In addition to DC and pulsed voltage, a novel etching mode is developed to prepare light-emitting porous silicon by applying and holding-up a voltage in gradient steps form periodically, between the silicon wafer and a graphite electrode. Under same equivalent etching conditions, periodic gradient steps voltage etching can yield a porous silicon layer with stronger photoluminescence intensity and blue shift than the porous silicon layer prepared by DC or pulsed voltage etching. It has been found that the holding-up of the applied voltage during the etching process for defined interval of time is another significant future of this method, which highly affects the blue shift. This can be used for tailoring a porous layer with novel properties. The actual mechanism behind the blue shift is not clear exactly, even the experimental observation of atomic force microscope and purist measurements in support with quantum confinement model. It has been seen also from Fourier Transform Infrared study that interplays between O-Si-H and Si-H bond intensities play key role in deciding the efficiency of photoluminescence emission. Study of relative humidity sensing and photonic crystal properties of pours silicon samples has confirmed the advantages of the new adopted etching mode. The sensitivity at room temperature of porous silicon prepared by periodic gradient steps voltage etching was found to be about 70% as compared to 51% and 45% for the porous silicon prepared by DC and pulsed voltage etching, respectively. (author)

Defect and phase stability of solid solutions of Mg2X with an antifluorite structure: An ab initio study

International Nuclear Information System (INIS)

Viennois, Romain; Jund, Philippe; Colinet, Catherine; Tédenac, Jean-Claude

2012-01-01

First principles calculations are done for Mg 2 X (X=Si, Ge or Sn) antifluorite compounds and their solid solutions in order to investigate their pseudo-binary phase diagram. The formation energies of the end-member compounds agree qualitatively with the experiments. For X=Si and Ge, there is a complete solubility, but we observe a miscibility gap in the pseudo-binary phase diagram Mg 2 Si–Mg 2 Sn. This agrees with the most recent experiments and phase diagram assessments. Calculated electronic properties of Mg 2 Si 1−x Sn x alloys qualitatively agree with experiments and in particular the energy bandgap decreases when Si is substituted by Sn. Supercell calculations are also done in order to determine the most stable defects and the doping induced by these defects in the three end-member compounds. We find that the intrinsic n-doping in pure Mg 2 Si can be attributed to the presence of magnesium atoms in interstitial positions. In Mg 2 Ge and Mg 2 Sn, since other defects are stable, they can be also of p-type. - Graphical abstract: Evidence of a miscibility gap from the plot of the formation energy vs x Si (silicon content) for the solid solutions Mg 2 Si–Mg 2 Sn. Highlights: ► First-principles study of the stability of Mg 2 Si–Mg 2 X alloys (X=Ge or Sn) and their defects. ► Mg 2 Si–Mg 2 Ge alloys form a complete series of solid solutions. ► Miscibility gap is found in Mg 2 Si–Mg 2 Sn alloys. ► Interstitial defects are more stable in Mg 2 Si and induce n-doping.

Silicon Micromachined Microlens Array for THz Antennas

Science.gov (United States)

Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

2013-01-01

5 5 silicon microlens array was developed using a silicon micromachining technique for a silicon-based THz antenna array. The feature of the silicon micromachining technique enables one to microfabricate an unlimited number of microlens arrays at one time with good uniformity on a silicon wafer. This technique will resolve one of the key issues in building a THz camera, which is to integrate antennas in a detector array. The conventional approach of building single-pixel receivers and stacking them to form a multi-pixel receiver is not suited at THz because a single-pixel receiver already has difficulty fitting into mass, volume, and power budgets, especially in space applications. In this proposed technique, one has controllability on both diameter and curvature of a silicon microlens. First of all, the diameter of microlens depends on how thick photoresist one could coat and pattern. So far, the diameter of a 6- mm photoresist microlens with 400 m in height has been successfully microfabricated. Based on current researchers experiences, a diameter larger than 1-cm photoresist microlens array would be feasible. In order to control the curvature of the microlens, the following process variables could be used: 1. Amount of photoresist: It determines the curvature of the photoresist microlens. Since the photoresist lens is transferred onto the silicon substrate, it will directly control the curvature of the silicon microlens. 2. Etching selectivity between photoresist and silicon: The photoresist microlens is formed by thermal reflow. In order to transfer the exact photoresist curvature onto silicon, there needs to be etching selectivity of 1:1 between silicon and photoresist. However, by varying the etching selectivity, one could control the curvature of the silicon microlens. The figure shows the microfabricated silicon microlens 5 x5 array. The diameter of the microlens located in the center is about 2.5 mm. The measured 3-D profile of the microlens surface has a

Historical evidence of importance to the industrialization of flat-plate silicon photovoltaic systems. Volume 1: Executive summary

Science.gov (United States)

Smith, J. L.

1978-01-01

An analysis is given of the Low-Cost Silicon Solar Array Project plans for the industrialization of new production technologies expected to be forthcoming as a result of the project's technology development efforts. In particular, LSSA's mandate to insure an annual production capability of 500 MW peak for the photovoltaic supply industry by 1986 is critically examined. The examination focuses on one of the concerns behind this goal -- timely development of industrial capacity to supply anticipated demand. Some of the conclusions include: (1) construction of small-scale pilot plants should be undertaken only for purposes of technology development; (2) large-scale demonstrations should be undertaken only when the technology is well in hand; (3) commercial-scale production should be left to the private sector; (4) the 500-MW annual output goal should be shifted to Program Headquarters.

EDITORIAL: Special issue on silicon photonics

Science.gov (United States)

Reed, Graham; Paniccia, Mario; Wada, Kazumi; Mashanovich, Goran

2008-06-01

The technology now known as silicon photonics can be traced back to the pioneering work of Soref in the mid-1980s (see, for example, Soref R A and Lorenzo J P 1985 Electron. Lett. 21 953). However, the nature of the research conducted today, whilst it builds upon that early work, is unrecognizable in terms of technology metrics such as device efficiency, device data rate and device dimensions, and even in targeted applications areas. Today silicon photonics is still evolving, and is enjoying a period of unprecedented attention in terms of research focus. This has resulted in orders-of-magnitude improvement in device performance over the last few years to levels many thought were impossible. However, despite the existence of the research field for more than two decades, silicon is still regarded as a 'new' optical material, one that is being manipulated and modified to satisfy the requirements of a range of applications. This is somewhat ironic since silicon is one of the best known and most thoroughly studied materials, thanks to the electronics industry that has made silicon its material of choice. The principal reasons for the lack of study of this 'late developer' are that (i) silicon is an indirect bandgap material and (ii) it does not exhibit a linear electro-optic (Pockels) effect. The former condition means that it is difficult to make a laser in silicon based on the intrinsic performance of the material, and consequently, in recent years, researchers have attempted to modify the material to artificially engineer the conditions for lasing to be viable (see, for example, the review text, Jalali B et al 2008 Silicon Lasers in Silicon Photonics: The State of the Art ed G T Reed (New York: Wiley)). The latter condition means that optical modulators are intrinsically less efficient in silicon than in some other materials, particularly when targeting the popular telecommunications wavelengths around 1.55 μm. Therefore researchers have sought alternative

Porous silicon-based direct hydrogen sulphide fuel cells.

Science.gov (United States)

Dzhafarov, T D; Yuksel, S Aydin

2011-10-01

In this paper, the use of Au/porous silicon/Silicon Schottky type structure, as a direct hydrogen sulphide fuel cell is demonstrated. The porous silicon filled with hydrochlorid acid was developed as a proton conduction membrane. The Au/Porous Silicon/Silicon cells were fabricated by first creating the porous silicon layer in single-crystalline Si using the anodic etching under illumination and then deposition Au catalyst layer onto the porous silicon. Using 80 mM H2S solution as fuel the open circuit voltage of 0.4 V was obtained and maximum power density of 30 W/m2 at room temperature was achieved. These results demonstrate that the Au/Porous Silicon/Silicon direct hydrogen sulphide fuel cell which uses H2S:dH2O solution as fuel and operates at room temperature can be considered as the most promising type of low cost fuel cell for small power-supply units.

Silicon based light-emitting materials and devices

International Nuclear Information System (INIS)

Chen Weide

1999-01-01

Silicon based light-emitting materials and devices are the key to optoelectronic integration. Recently, there has been significant progress in materials engineering methods. The author reviews the latest developments in this area including erbium doped silicon, porous silicon, nanocrystalline silicon and Si/SiO 2 superlattice structures. The incorporation of these different materials into devices is described and future device prospects are assessed

Vibrational Spectroscopy of Chemical Species in Silicon and Silicon-Rich Nitride Thin Films

Directory of Open Access Journals (Sweden)

Kirill O. Bugaev

2012-01-01

Full Text Available Vibrational properties of hydrogenated silicon-rich nitride (SiN:H of various stoichiometry (0.6≤≤1.3 and hydrogenated amorphous silicon (a-Si:H films were studied using Raman spectroscopy and Fourier transform infrared spectroscopy. Furnace annealing during 5 hours in Ar ambient at 1130∘C and pulse laser annealing were applied to modify the structure of films. Surprisingly, after annealing with such high-thermal budget, according to the FTIR data, the nearly stoichiometric silicon nitride film contains hydrogen in the form of Si–H bonds. From analysis of the FTIR data of the Si–N bond vibrations, one can conclude that silicon nitride is partly crystallized. According to the Raman data a-Si:H films with hydrogen concentration 15% and lower contain mainly Si–H chemical species, and films with hydrogen concentration 30–35% contain mainly Si–H2 chemical species. Nanosecond pulse laser treatments lead to crystallization of the films and its dehydrogenization.

P-type silicon drift detectors

International Nuclear Information System (INIS)

Walton, J.T.; Krieger, B.; Krofcheck, D.; O'Donnell, R.; Odyniec, G.; Partlan, M.D.; Wang, N.W.

1995-06-01

Preliminary results on 16 CM 2 , position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 x l0 6 s -1 is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 μm to 1200 μm. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed

Porous silicon investigated by positron annihilation

International Nuclear Information System (INIS)

Cruz, R.M. de la; Pareja, R.

1989-01-01

The effect of the anodic conversion in silicon single crystals is investigated by positron lifetime measurements. Anodization at constant current induces changes in the positron lifetime spectrum of monocrystalline silicon samples. It is found that theses changes are primarily dependent on the silicon resistivity. The annihilation parameter behaviour of anodized samples, treated at high temperature under reducing conditions, is also investigated. The results reveal that positron annihilation can be a useful technique to characterize porous silicon formed by anodizing as well as to investigate its thermal behaviour. (author)

Structural, optical and electrical properties of quasi-monocrystalline silicon thin films obtained by rapid thermal annealing of porous silicon layers

International Nuclear Information System (INIS)

Hajji, M.; Khardani, M.; Khedher, N.; Rahmouni, H.; Bessais, B.; Ezzaouia, H.; Bouchriha, H.

2006-01-01

Quasi-mono-crystalline silicon (QMS) layers have a top surface like crystalline silicon with small voids in the body. Such layers are reported to have a higher absorption coefficient than crystalline silicon at the interesting range of the solar spectrum for photovoltaic application. In this work we present a study of the structural, optical and electrical properties of quasimonocrystalline silicon thin films. Quasimonocrystalline silicon thin films were obtained from porous silicon, which has been annealed at a temperature ranging from 950 to 1050 deg. C under H 2 atmosphere for different annealing durations. The porous layers were prepared by conventional electrochemical anodization using a double tank cell and a HF / Ethanol electrolyte. Porous silicon is formed on highly doped p + -type silicon substrates that enable us to prevent back contacts for the anodization. Atomic Force Microscope (AFM) was used to study the morphological quality of the prepared layers. Optical properties were extracted from transmission and reflectivity spectra. Dark I-V characteristics were used to determine the electrical conductivity of quasimonocrystalline silicon thin films. Results show an important improvement of the absorption coefficient of the material and electrical conductivity reaches a value of twenty orders higher than that of starting mesoporous silicon

Characterization of Czochralski Silicon Detectors

OpenAIRE

Luukka, Panja-Riina; Haerkoenen, Jaakko

2012-01-01

This thesis describes the characterization of irradiated and non-irradiated segmenteddetectors made of high-resistivity (>1 kΩcm) magnetic Czochralski (MCZ) silicon. It isshown that the radiation hardness (RH) of the protons of these detectors is higher thanthat of devices made of traditional materials such as Float Zone (FZ) silicon or DiffusionOxygenated Float Zone (DOFZ) silicon due to the presence of intrinsic oxygen (> 5 x1017 cm-3). The MCZ devices therefore present an interesting alter...

Structure and physical properties of silicon clusters and of vacancy clusters in bulk silicon

International Nuclear Information System (INIS)

Sieck, A.

2000-01-01

In this thesis the growth-pattern of free silicon clusters and vacancy clusters in bulk silicon is investigated. The aim is to describe and to better understand the cluster to bulk transition. Silicon structures in between clusters and solids feature new interesting physical properties. The structure and physical properties of silicon clusters can be revealed by a combination of theory and experiment, only. Low-energy clusters are determined with different optimization techniques and a density-functional based tight-binding method. Additionally, infrared and Raman spectra, and polarizabilities calculated within self-consistent field density-functional theory are provided for the smaller clusters. For clusters with 25 to 35 atoms an analysis of the shape of the clusters and the related mobilities in a buffer gas is given. Finally, the clusters observed in low-temperature experiments are identified via the best match between calculated properties and experimental data. Silicon clusters with 10 to 15 atoms have a tricapped trigonal prism as a common subunit. Clusters with up to about 25 atoms follow a prolate growth-path. In the range from 24 to 30 atoms the geometry of the clusters undergoes a transition towards compact spherical structures. Low-energy clusters with up to 240 atoms feature a bonding pattern strikingly different from the tetrahedral bonding in the solid. It follows that structures with dimensions of several Angstroem have electrical and optical properties different from the solid. The calculated stabilities and positron-lifetimes of vacancy clusters in bulk silicon indicate the positron-lifetimes of about 435 ps detected in irradiated silicon to be related to clusters of 9 or 10 vacancies. The vacancies in these clusters form neighboring hexa-rings and, therefore, minimize the number of dangling bonds. (orig.)

Solar cells with gallium phosphide/silicon heterojunction

Science.gov (United States)

Darnon, Maxime; Varache, Renaud; Descazeaux, Médéric; Quinci, Thomas; Martin, Mickaël; Baron, Thierry; Muñoz, Delfina

2015-09-01

One of the limitations of current amorphous silicon/crystalline silicon heterojunction solar cells is electrical and optical losses in the front transparent conductive oxide and amorphous silicon layers that limit the short circuit current. We propose to grow a thin (5 to 20 nm) crystalline Gallium Phosphide (GaP) by epitaxy on silicon to form a more transparent and more conducting emitter in place of the front amorphous silicon layers. We show that a transparent conducting oxide (TCO) is still necessary to laterally collect the current with thin GaP emitter. Larger contact resistance of GaP/TCO increases the series resistance compared to amorphous silicon. With the current process, losses in the IR region associated with silicon degradation during the surface preparation preceding GaP deposition counterbalance the gain from the UV region. A first cell efficiency of 9% has been obtained on ˜5×5 cm2 polished samples.

Electrical properties of pressure quenched silicon by thermal spraying

International Nuclear Information System (INIS)

Tan, S.Y.; Gambino, R.J.; Sampath, S.; Herman, H.

2007-01-01

High velocity thermal spray deposition of polycrystalline silicon film onto single crystal substrates, yields metastable high pressure forms of silicon in nanocrystalline form within the deposit. The phases observed in the deposit include hexagonal diamond-Si, R-8, BC-8 and Si-IX. The peculiar attribute of this transformation is that it occurs only on orientation silicon substrate. The silicon deposits containing the high pressure phases display a substantially higher electrical conductivity. The resistivity profile of the silicon deposit containing shock induced metastable silicon phases identified by X-ray diffraction patterns. The density of the pressure induced polymorphic silicon is higher at deposit/substrate interface. A modified two-layer model is presented to explain the resistivity of the deposit impacted by the pressure induced polymorphic silicon generated by the thermal spraying process. The pressure quenched silicon deposits on the p - silicon substrate, with or without metastable phases, display the barrier potential of about 0.72 eV. The measured hall mobility value of pressure quenched silicon deposits is in the range of polycrystalline silicon. The significance of this work lies in the fact that the versatility of thermal spray may enable applications of these high pressure forms of silicon

Silicon Chemistry in the Mesosphere and Lower Thermosphere

Science.gov (United States)

Plane, John M. C.; Gomez-Martin, Juan Carlos; Feng, Wuhu; Janches, Diego

2016-01-01

Silicon is one of the most abundant elements in cosmic dust, and meteoric ablation injects a significant amount of Si into the atmosphere above 80 km. In this study, a new model for silicon chemistry in the mesosphere lower thermosphere is described, based on recent laboratory kinetic studies of Si, SiO,SiO2, and S(exp +). Electronic structure calculations and statistical rate theory are used to show that the likely fate of SiO2 is a two-step hydration to silicic acid (Si(OH)4), which then polymerizes with metal oxides and hydroxides to form meteoric smoke particles. This chemistry is then incorporated into a whole atmosphere chemistry-climate model. The vertical profiles of Si+ and the Si(exp +)Fe(exp +) ratio are shown to be in good agreement with rocket-borne mass spectrometric measurements between 90 and 110 km. Si(exp +) has consistently been observed to be the major meteoric ion around 110 km; this implies that the relative injection rate of Si from meteoric ablation, compared to metals such as Fe and Mg, is significantly larger than expected based on the irrelative chondritic abundances. Finally, the global abundances of SiO and Si(OH)4 show clear evidence of the seasonal meteoric input function, which is much less pronounced in the case of other meteoric species.

Highly stable carbon coated Mg2Si intermetallic nanoparticles for lithium-ion battery anode

Science.gov (United States)

Tamirat, Andebet Gedamu; Hou, Mengyan; Liu, Yao; Bin, Duan; Sun, Yunhe; Fan, Long; Wang, Yonggang; Xia, Yongyao

2018-04-01

Silicon is an ideal candidate anode material for Li-ion batteries (LIBs). However, it suffers from rapid capacity fading due to large volume expansion upon lithium insertion. Herein, we design and fabricate highly stable carbon coated porous Mg2Si intermetallic anode material using facile mechano-thermal technique followed by carbon coating using thermal vapour deposition (TVD), toluene as carbon source. The electrode exhibits an excellent first reversible capacity of 726 mAh g-1 at a rate of 100 mA g-1. More importantly, the electrode demonstrates high rate capability (380 mAh g-1 at high rate of 2 A g-1) as well as high cycle stability, with capacity retentions of 65% over 500 cycles. These improvements are attributable to both Mg supporting medium and the uniform carbon coating, which can effectively increase the conductivity and electronic contact of the active material and protects large volume alterations during the electrochemical cycling process.

Corrosion Behavior of Heat-Treated AlSi10Mg Manufactured by Laser Powder Bed Fusion

Directory of Open Access Journals (Sweden)

Marina Cabrini

2018-06-01

Full Text Available This experimental work is aimed at studying the effect of microstructural modifications induced by post-processing heat treatments on the corrosion behavior of silicon-aluminum alloys produced by means of laser powder bed fusion (LPBF. The manufacturing technique leads to microstructures characterized by the presence of melt pools, which are quite different compared to casting alloys. In this study, the behavior of an AlSi10Mg alloy was evaluated by means of intergranular corrosion tests according to ISO 11846 standard on heat-treated samples ranging from 200 to 500 °C as well as on untreated samples. We found that temperatures above 200 °C reduced microhardness of the alloy, and different corrosion morphologies occurred due to the modification of both size and distribution of silicon precipitates. Selective penetrating attacks occurred at melt pool borders. The intergranular corrosion phenomena were less intense for as-produced specimens without heat treatments compared to the heat-treated specimens at 200 and 300 °C. General corrosion morphologies were noticed for specimens heat treated at temperatures exceeding 400 °C.

Damage-free laser patterning of silicon nitride on textured crystalline silicon using an amorphous silicon etch mask for Ni/Cu plated silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Bailly, Mark S., E-mail: mbailly@asu.edu; Karas, Joseph; Jain, Harsh; Dauksher, William J.; Bowden, Stuart

2016-08-01

We investigate the optimization of laser ablation with a femtosecond laser for direct and indirect removal of SiN{sub x} on alkaline textured c-Si. Our proposed resist-free indirect removal process uses an a-Si:H etch mask and is demonstrated to have a drastically improved surface quality of the laser processed areas when compared to our direct removal process. Scanning electron microscope images of ablated sites show the existence of substantial surface defects for the standard direct removal process, and the reduction of those defects with our proposed process. Opening of SiN{sub x} and SiO{sub x} passivating layers with laser ablation is a promising alternative to the standard screen print and fire process for making contact to Si solar cells. The potential for small contacts from laser openings of dielectrics coupled with the selective deposition of metal from light induced plating allows for high-aspect-ratio metal contacts for front grid metallization. The minimization of defects generated in this process would serve to enhance the performance of the device and provides the motivation for our work. - Highlights: • Direct laser removal of silicon nitride (SiN{sub x}) damages textured silicon. • Direct laser removal of amorphous silicon (a-Si) does not damage textured silicon. • a-Si can be used as a laser patterned etch mask for SiN{sub x}. • Chemically patterned SiN{sub x} sites allow for Ni/Cu plating.

Electrochemical properties of ion implanted silicon

International Nuclear Information System (INIS)

Pham minh Tan.

1979-11-01

The electrochemical behaviour of ion implanted silicon in contact with hydrofluoric acid solution was investigated. It was shown that the implanted layer on silicon changes profoundly its electrochemical properties (photopotential, interface impedance, rest potential, corrosion, current-potential behaviour, anodic dissolution of silicon, redox reaction). These changes depend strongly on the implantation parameters such as ion dose, ion energy, thermal treatment and ion mass and are weakly dependent on the chemical nature of the implantation ion. The experimental results were evaluated and interpreted in terms of the semiconductor electrochemical concepts taking into account the interaction of energetic ions with the solid surface. The observed effects are thus attributed to the implantation induced damage of silicon lattice and can be used for profiling of the implanted layer and the electrochemical treatment of the silicon surface. (author)

Fabricating solar cells with silicon nanoparticles

Science.gov (United States)

Loscutoff, Paul; Molesa, Steve; Kim, Taeseok

2014-09-02

A laser contact process is employed to form contact holes to emitters of a solar cell. Doped silicon nanoparticles are formed over a substrate of the solar cell. The surface of individual or clusters of silicon nanoparticles is coated with a nanoparticle passivation film. Contact holes to emitters of the solar cell are formed by impinging a laser beam on the passivated silicon nanoparticles. For example, the laser contact process may be a laser ablation process. In that case, the emitters may be formed by diffusing dopants from the silicon nanoparticles prior to forming the contact holes to the emitters. As another example, the laser contact process may be a laser melting process whereby portions of the silicon nanoparticles are melted to form the emitters and contact holes to the emitters.

Impacts of Steel-Slag-Based Silicate Fertilizer on Soil Acidity and Silicon Availability and Metals-Immobilization in a Paddy Soil.

Directory of Open Access Journals (Sweden)

Dongfeng Ning

Full Text Available Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. A consecutive early rice-late rice rotation experiment was conducted to test the impacts of steel slag on soil pH, silicon availability, rice growth and metals-immobilization in paddy soil. Our results show that application of slag at a rate above higher or equal to 1 600 mg plant-available SiO2 per kg soil increased soil pH, dry weight of rice straw and grain, plant-available Si concentration and Si concentration in rice shoots compared with the control treatment. No significant accumulation of total cadmium (Cd and lead (Pb was noted in soil; rather, the exchangeable fraction of Cd significantly decreased. The cadmium concentrations in rice grains decreased significantly compared with the control treatment. In conclusion, application of steel slag reduced soil acidity, increased plant-availability of silicon, promoted rice growth and inhibited Cd transport to rice grain in the soil-plant system.

Formation and properties of the buried isolating silicon-dioxide layer in double-layer “porous silicon-on-insulator” structures

Energy Technology Data Exchange (ETDEWEB)

Bolotov, V. V.; Knyazev, E. V.; Ponomareva, I. V.; Kan, V. E., E-mail: kan@obisp.oscsbras.ru; Davletkildeev, N. A.; Ivlev, K. E.; Roslikov, V. E. [Russian Academy of Sciences, Omsk Scientific Center, Siberian Branch (Russian Federation)

2017-01-15

The oxidation of mesoporous silicon in a double-layer “macroporous silicon–mesoporous silicon” structure is studied. The morphology and dielectric properties of the buried insulating layer are investigated using electron microscopy, ellipsometry, and electrical measurements. Specific defects (so-called spikes) are revealed between the oxidized macropore walls in macroporous silicon and the oxidation crossing fronts in mesoporous silicon. It is found that, at an initial porosity of mesoporous silicon of 60%, three-stage thermal oxidation leads to the formation of buried silicon-dioxide layers with an electric-field breakdown strength of E{sub br} ~ 10{sup 4}–10{sup 5} V/cm. Multilayered “porous silicon-on-insulator” structures are shown to be promising for integrated chemical micro- and nanosensors.

Annual report 1992 of the German Federal Food Research Institute, BFE

International Nuclear Information System (INIS)

1993-02-01

The 1992 annual report of the BFE explains the tasks and responsibilities of the institution, its organisational structure and manpower, as well as the main research activities or scientific activities performed in cooperation with other institutions. From the wide range of research activities, food irradiation and environmental radioactivity in food are heading the list of tasks performed. (MG) [de

Emerging heterogeneous integrated photonic platforms on silicon

Directory of Open Access Journals (Sweden)

Fathpour Sasan

2015-05-01

Full Text Available Silicon photonics has been established as a mature and promising technology for optoelectronic integrated circuits, mostly based on the silicon-on-insulator (SOI waveguide platform. However, not all optical functionalities can be satisfactorily achieved merely based on silicon, in general, and on the SOI platform, in particular. Long-known shortcomings of silicon-based integrated photonics are optical absorption (in the telecommunication wavelengths and feasibility of electrically-injected lasers (at least at room temperature. More recently, high two-photon and free-carrier absorptions required at high optical intensities for third-order optical nonlinear effects, inherent lack of second-order optical nonlinearity, low extinction ratio of modulators based on the free-carrier plasma effect, and the loss of the buried oxide layer of the SOI waveguides at mid-infrared wavelengths have been recognized as other shortcomings. Accordingly, several novel waveguide platforms have been developing to address these shortcomings of the SOI platform. Most of these emerging platforms are based on heterogeneous integration of other material systems on silicon substrates, and in some cases silicon is integrated on other substrates. Germanium and its binary alloys with silicon, III–V compound semiconductors, silicon nitride, tantalum pentoxide and other high-index dielectric or glass materials, as well as lithium niobate are some of the materials heterogeneously integrated on silicon substrates. The materials are typically integrated by a variety of epitaxial growth, bonding, ion implantation and slicing, etch back, spin-on-glass or other techniques. These wide range of efforts are reviewed here holistically to stress that there is no pure silicon or even group IV photonics per se. Rather, the future of the field of integrated photonics appears to be one of heterogenization, where a variety of different materials and waveguide platforms will be used for

Water-saving ground cover rice production system reduces net greenhouse gas fluxes in an annual rice-based cropping system

Science.gov (United States)

Yao, Z.; Du, Y.; Tao, Y.; Zheng, X.; Liu, C.; Lin, S.; Butterbach-Bahl, K.

2014-11-01

To safeguard food security and preserve precious water resources, the technology of water-saving ground cover rice production system (GCRPS) is being increasingly adopted for rice cultivation. However, changes in soil water status and temperature under GCRPS may affect soil biogeochemical processes that control the biosphere-atmosphere exchanges of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). The overall goal of this study is to better understand how net ecosystem greenhouse gas exchanges (NEGE) and grain yields are affected by GCRPS in an annual rice-based cropping system. Our evaluation was based on measurements of the CH4 and N2O fluxes and soil heterotrophic respiration (CO2 emissions) over a complete year, and the estimated soil carbon sequestration intensity for six different fertilizer treatments for conventional paddy and GCRPS. The fertilizer treatments included urea application and no N fertilization for both conventional paddy (CUN and CNN) and GCRPS (GUN and GNN), and solely chicken manure (GCM) and combined urea and chicken manure applications (GUM) for GCRPS. Averaging across all the fertilizer treatments, GCRPS increased annual N2O emission and grain yield by 40 and 9%, respectively, and decreased annual CH4 emission by 69%, while GCRPS did not affect soil CO2 emissions relative to the conventional paddy. The annual direct emission factors of N2O were 4.01, 0.09 and 0.50% for GUN, GCM and GUM, respectively, and 1.52% for the conventional paddy (CUN). The annual soil carbon sequestration intensity under GCRPS was estimated to be an average of -1.33 Mg C ha-1 yr-1, which is approximately 44% higher than the conventional paddy. The annual NEGE were 10.80-11.02 Mg CO2-eq ha-1 yr-1 for the conventional paddy and 3.05-9.37 Mg CO2-eq ha-1 yr-1 for the GCRPS, suggesting the potential feasibility of GCRPS in reducing net greenhouse effects from rice cultivation. Using organic fertilizers for GCRPS considerably reduced annual emissions of CH4

Vapor phase epitaxy of silicon on meso porous silicon for deposition on economical substrate and low cost photovoltaic application

International Nuclear Information System (INIS)

Quoizola, S.

2003-01-01

The silicon is more and more used in the industry. Meanwhile the production cost is a problem to solve to develop the photovoltaic cells production. This thesis presents a new technology based on the use of a meso-porous silicon upper layer,to grow the active silicon layer of 50 μm width. The photovoltaic cell is then realized, the device is removed and placed on a low cost substrate. The silicon substrate of beginning can be used again after cleaning. The first chapter presents the operating and the characteristics of the silicon photovoltaic cell. The second chapter is devoted to the growth technique, the vapor phase epitaxy, and the third chapter to the epitaxy layer. The chapter four deals with the porous silicon and the structure chosen in this study. The chapter five is devoted to the characterization of the epitaxy layer on porous silicon. The photovoltaic cells realized on these layers are presented in the last chapter. (A.L.B.)

Next generation structural silicone glazing

Directory of Open Access Journals (Sweden)

Charles D. Clift

2015-06-01

Full Text Available This paper presents an advanced engineering evaluation, using nonlinear analysis of hyper elastic material that provides significant improvement to structural silicone glazing (SSG design in high performance curtain wall systems. Very high cladding wind pressures required in hurricane zones often result in bulky SSG profile dimensions. Architectural desire for aesthetically slender curtain wall framing sight-lines in combination with a desire to reduce aluminium usage led to optimization of silicone material geometry for better stress distribution.To accomplish accurate simulation of predicted behaviour under structural load, robust stress-strain curves of the silicone material are essential. The silicone manufacturer provided physical property testing via a specialized laboratory protocol. A series of rigorous curve fit techniques were then made to closely model test data in the finite element computer analysis that accounts for nonlinear strain of hyper elastic silicone.Comparison of this advanced design technique to traditional SSG design highlights differences in stress distribution contours in the silicone material. Simplified structural engineering per the traditional SSG design method does not provide accurate forecasting of material and stress optimization as shown in the advanced design.Full-scale specimens subject to structural load testing were performed to verify the design capacity, not only for high wind pressure values, but also for debris impact per ASTM E1886 and ASTM E1996. Also, construction of the test specimens allowed development of SSG installation techniques necessitated by the unique geometry of the silicone profile. Finally, correlation of physical test results with theoretical simulations is made, so evaluation of design confidence is possible. This design technique will introduce significant engineering advancement to the curtain wall industry.

Annual methane budgets of sheep grazing systems were regulated by grazing intensities in the temperate continental steppe: A two-year case study

Science.gov (United States)

Ma, Lei; Zhong, Mengying; Zhu, Yuhao; Yang, Helong; Johnson, Douglas A.; Rong, Yuping

2018-02-01

Methane (CH4) emission from animal husbandry accounts for a large percentage of anthropogenic contributions to CH4 emissions. Fully understanding of grazing management effects on the CH4 budget is essential for mitigating CH4 emissions in the temperate grazing steppe systems. Annual CH4 budgets for the sheep grazed steppes at various grazing intensities, un-grazing (UG, 0 sheep ha-1year-1), defer grazing (DG, 1.0 sheep ha-1 year-1), moderate grazing (MG, 1.43 sheep ha-1year-1), and heavy grazing (HG, 2.43 sheep ha-1year-1) were assessed across 2012-2014 in the agro-pastoral region of northern China. Annual soil CH4 uptake averaged across 2012-2014 were 1.1 ± 0.1, 2.4 ± 0.2, 2.2 ± 0.2, and 1.3 ± 0.1 kg CH4-C ha-1 for UG, DG (only 2013-2014), MG and HG sites. Non-growing season CH4 uptake comprised 50.0 ± 4.3% of annual CH4 uptake in 2012-2013 and 37.7 ± 2.0% in 2013-2014. DG and MG significantly promoted annual soil CH4 uptake (P 0.05). Bell-shaped relationship was presented between stocking rates and soil CH4 uptake (r2 = 0.59, P budgets for the grazed grasslands were -1.1 ± 0.1, 5.7 ± 0.6, 11.5 ± 1.5 and 15.5 ± 1.3 kg CH4-C ha-1 year-1 in UG, DG (only 2013-2014), MG and HG across 2012-2014. Soil CH4 uptake could offset 29.7 ± 5.6, 15.9 ± 4.3 and 6.8 ± 1.0% of total annual CH4 emissions from sheep, sheepfold and faeces in DG, MG, and HG. All grazed steppes are sources for atmospheric CH4 and the magnitude is regulated by grazing intensities. Sheep CH4 emissions for 1-g liveweight gain were 0.21, 0.32 and 0.37 g CH4-C in DG, MG and HG, respectively. DG is the recommended grazing management in this region to achieve greater herbage mass, higher sheep performance and lower CH4 emissions simultaneously.

Fabrication of p-type porous GaN on silicon and epitaxial GaN

OpenAIRE

Bilousov, Oleksandr V.; Geaney, Hugh; Carvajal, Joan J.; Zubialevich, Vitaly Z.; Parbrook, Peter J.; Giguere, A.; Drouin, D.; Diaz, Francesc; Aguilo, Magdalena; O'Dwyer, Colm

2013-01-01

Porous GaN layers are grown on silicon from gold or platinum catalyst seed layers, and self-catalyzed on epitaxial GaN films on sapphire. Using a Mg-based precursor, we demonstrate p-type doping of the porous GaN. Electrical measurements for p-type GaN on Si show Ohmic and Schottky behavior from gold and platinum seeded GaN, respectively. Ohmicity is attributed to the formation of a Ga2Au intermetallic. Porous p-type GaN was also achieved on epitaxial n-GaN on sapphire, and transport measurem...

Stable configurations of graphene on silicon

Energy Technology Data Exchange (ETDEWEB)

Javvaji, Brahmanandam; Shenoy, Bhamy Maithry [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Mahapatra, D. Roy, E-mail: droymahapatra@aero.iisc.ernet.in [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Ravikumar, Abhilash [Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025 (India); Hegde, G.M. [Center for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012 (India); Rizwan, M.R. [Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025 (India)

2017-08-31

Highlights: • Simulations of epitaxial growth process for silicon–graphene system is performed. • Identified the most favourable orientation of graphene sheet on silicon substrate. • Atomic local strain due to the silicon–carbon bond formation is analyzed. - Abstract: Integration of graphene on silicon-based nanostructures is crucial in advancing graphene based nanoelectronic device technologies. The present paper provides a new insight on the combined effect of graphene structure and silicon (001) substrate on their two-dimensional anisotropic interface. Molecular dynamics simulations involving the sub-nanoscale interface reveal a most favourable set of temperature independent orientations of the monolayer graphene sheet with an angle of ∽15° between its armchair direction and [010] axis of the silicon substrate. While computing the favorable stable orientations, both the translation and the rotational vibrations of graphene are included. The possible interactions between the graphene atoms and the silicon atoms are identified from their coordination. Graphene sheet shows maximum bonding density with bond length 0.195 nm and minimum bond energy when interfaced with silicon substrate at 15° orientation. Local deformation analysis reveals probability distribution with maximum strain levels of 0.134, 0.047 and 0.029 for 900 K, 300 K and 100 K, respectively in silicon surface for 15° oriented graphene whereas the maximum probable strain in graphene is about 0.041 irrespective of temperature. Silicon–silicon dimer formation is changed due to silicon–carbon bonding. These results may help further in band structure engineering of silicon–graphene lattice.

Improved Optics in Monolithic Perovskite/Silicon Tandem Solar Cells with a Nanocrystalline Silicon Recombination Junction

KAUST Repository

Sahli, Florent

2017-10-09

Perovskite/silicon tandem solar cells are increasingly recognized as promi­sing candidates for next-generation photovoltaics with performance beyond the single-junction limit at potentially low production costs. Current designs for monolithic tandems rely on transparent conductive oxides as an intermediate recombination layer, which lead to optical losses and reduced shunt resistance. An improved recombination junction based on nanocrystalline silicon layers to mitigate these losses is demonstrated. When employed in monolithic perovskite/silicon heterojunction tandem cells with a planar front side, this junction is found to increase the bottom cell photocurrent by more than 1 mA cm−2. In combination with a cesium-based perovskite top cell, this leads to tandem cell power-conversion efficiencies of up to 22.7% obtained from J–V measurements and steady-state efficiencies of up to 22.0% during maximum power point tracking. Thanks to its low lateral conductivity, the nanocrystalline silicon recombination junction enables upscaling of monolithic perovskite/silicon heterojunction tandem cells, resulting in a 12.96 cm2 monolithic tandem cell with a steady-state efficiency of 18%.

Improved Optics in Monolithic Perovskite/Silicon Tandem Solar Cells with a Nanocrystalline Silicon Recombination Junction

KAUST Repository

Sahli, Florent; Kamino, Brett A.; Werner, Jé ré mie; Brä uninger, Matthias; Paviet-Salomon, Bertrand; Barraud, Loris; Monnard, Raphaë l; Seif, Johannes Peter; Tomasi, Andrea; Jeangros, Quentin; Hessler-Wyser, Aï cha; De Wolf, Stefaan; Despeisse, Matthieu; Nicolay, Sylvain; Niesen, Bjoern; Ballif, Christophe

2017-01-01

Perovskite/silicon tandem solar cells are increasingly recognized as promi­sing candidates for next-generation photovoltaics with performance beyond the single-junction limit at potentially low production costs. Current designs for monolithic tandems rely on transparent conductive oxides as an intermediate recombination layer, which lead to optical losses and reduced shunt resistance. An improved recombination junction based on nanocrystalline silicon layers to mitigate these losses is demonstrated. When employed in monolithic perovskite/silicon heterojunction tandem cells with a planar front side, this junction is found to increase the bottom cell photocurrent by more than 1 mA cm−2. In combination with a cesium-based perovskite top cell, this leads to tandem cell power-conversion efficiencies of up to 22.7% obtained from J–V measurements and steady-state efficiencies of up to 22.0% during maximum power point tracking. Thanks to its low lateral conductivity, the nanocrystalline silicon recombination junction enables upscaling of monolithic perovskite/silicon heterojunction tandem cells, resulting in a 12.96 cm2 monolithic tandem cell with a steady-state efficiency of 18%.

Discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys as anodes for Mg-air battery

International Nuclear Information System (INIS)

Wang, Naiguang; Wang, Richu; Peng, Chaoqun; Peng, Bing; Feng, Yan; Hu, Chengwang

2014-01-01

Highlights: • We investigate the effect of indium on the discharge behaviour of Mg-Al-Pb alloy. • We evaluate the performance of Mg-air batteries with Mg-Al-Pb and Mg-Al-Pb-In anodes. • We analyze the activation mechanism of Mg-Al-Pb-In alloy in the discharge process. - Abstract: The discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys in 3.5 wt.% NaCl solution is investigated by electrochemical techniques, and compared with that of pure magnesium. The results show that Mg-Al-Pb-In alloy provides a more negative potential and exhibits a higher utilization efficiency in contrast with Mg-Al-Pb alloy and pure magnesium during the half-cell test at a large current density, and gives desirable discharge performance when used as anode for Mg- air battery. The peak power density of the Mg-air battery with Mg-Al-Pb-In anode is 94.5 mW cm −2 , which is comparable with those of Mg-H 2 O 2 semi-fuel batteries. Moreover, the activation mechanism of Mg-Al-Pb-In alloy during the discharge process is also analyzed

Toxicities of Selected Essential Oils, Silicone Oils, and Paraffin Oil against the Common Bed Bug (Hemiptera: Cimicidae).

Science.gov (United States)

Zha, Chen; Wang, Changlu; Li, Andrew

2018-02-09

The common bed bug [Cimex lectularius L. (Hemiptera: Cimicidae)] and tropical bed bug [Cimex hemipterus F. (Hemiptera: Cimicidae)] resurged in the United States and many other countries over the past decades. The need for safe and effective bed bug control products propelled the development of numerous 'green insecticides', mostly with essential oils listed as active ingredients. Various inorganic and organic oils also were used for bed bug management. However, there are no published studies on their toxicities against bed bugs. In this study, we screened 18 essential oils, three silicone oils, and paraffin oil (C5-20 paraffins) for their toxicities against bed bugs. All the oils exhibited insecticidal activity in topical assays. Their toxicities varied significantly; all of the evaluated essential oils were less effective than silicone oils and paraffin oil. The LD50 values of the most effective essential oil (blood orange), paraffin oil, and the most effective silicone oil (dodecamethylpentasiloxane) are 0.184 ± 0.018, 0.069 ± 0.012, and 0.036 ± 0.005 mg per bug, respectively. Direct spray of 1% water solution of 3-[hydroxy (polyethyleneoxy) propyl] heptamethyltrisiloxane, the only silicone oil that mixes well with water, resulted in 92% bed bug mortality after 1 d. Results of this study indicate silicone oils and paraffin oil have the potential to be used as safer alternative bed bug control materials. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Study of effects of radiation on silicone prostheses

International Nuclear Information System (INIS)

Shedbalkar, A.R.; Devata, A.; Padanilam, T.

1980-01-01

Radiation effects on silicone gel and dose distribution of radiation through mammary prostheses were studied. Silicone gel behaves like tissue. Half value thickness for silicone gel and water are almost the same. Linear absorption coefficient for silicone gel and water are comparable

Method of fabricating porous silicon carbide (SiC)

Science.gov (United States)

Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

1995-01-01

Porous silicon carbide is fabricated according to techniques which result in a significant portion of nanocrystallites within the material in a sub 10 nanometer regime. There is described techniques for passivating porous silicon carbide which result in the fabrication of optoelectronic devices which exhibit brighter blue luminescence and exhibit improved qualities. Based on certain of the techniques described porous silicon carbide is used as a sacrificial layer for the patterning of silicon carbide. Porous silicon carbide is then removed from the bulk substrate by oxidation and other methods. The techniques described employ a two-step process which is used to pattern bulk silicon carbide where selected areas of the wafer are then made porous and then the porous layer is subsequently removed. The process to form porous silicon carbide exhibits dopant selectivity and a two-step etching procedure is implemented for silicon carbide multilayers.

HRTEM analysis of the nanostructure of porous silicon

International Nuclear Information System (INIS)

Martin-Palma, R.J.; Pascual, L.; Landa-Canovas, A.R.; Herrero, P.; Martinez-Duart, J.M.

2006-01-01

The nanometric structure of porous silicon makes this material to be very suitable for its use in many different fields, including optoelectronics and biological applications. In the present work, the structure of porous silicon was investigated in detail by means of cross-sectional high-resolution transmission electron microscopy and digital image processing, together with electron energy loss spectroscopy. The structure of the Si/porous silicon interface and that of the silicon nanocrystals that compose porous silicon have been analyzed in detail. A strong strain contrast in the Si/porous silicon interface caused by high stresses was observed. Accordingly, dislocation pairs are found to be a possible mechanism of lattice matching between porous silicon and the Si substrate. Finally, high relative concentration of oxygen in the porous silicon layer was observed, together with low relative electron concentration in the conduction band when compared to Si

Evaluation of selected chemical processes for production of low-cost silicon phase 2. silicon material task, low-cost silicon solar array project

Science.gov (United States)

Blocher, J. M., Jr.; Browning, M. F.; Rose, E. E.; Thompson, W. B.; Schmitt, W. A.; Fippin, J. S.; Kidd, R. W.; Liu, C. Y.; Kerbler, P. S.; Ackley, W. R.

1978-01-01

Progress from October 1, 1977, through December 31, 1977, is reported in the design of the 50 MT/year experimental facility for the preparation of high purity silicon by the zinc vapor reduction of silicon tetrachloride in a fluidized bed of seed particles to form a free flowing granular product.

Effect of additive gases and injection methods on chemical dry etching of silicon nitride, silicon oxynitride, and silicon oxide layers in F2 remote plasmas

International Nuclear Information System (INIS)

Yun, Y. B.; Park, S. M.; Kim, D. J.; Lee, N.-E.; Kim, K. S.; Bae, G. H.

2007-01-01

The authors investigated the effects of various additive gases and different injection methods on the chemical dry etching of silicon nitride, silicon oxynitride, and silicon oxide layers in F 2 remote plasmas. N 2 and N 2 +O 2 gases in the F 2 /Ar/N 2 and F 2 /Ar/N 2 /O 2 remote plasmas effectively increased the etch rate of the layers. The addition of direct-injected NO gas increased the etch rates most significantly. NO radicals generated by the addition of N 2 and N 2 +O 2 or direct-injected NO molecules contributed to the effective removal of nitrogen and oxygen in the silicon nitride and oxide layers, by forming N 2 O and NO 2 by-products, respectively, and thereby enhancing SiF 4 formation. As a result of the effective removal of the oxygen, nitrogen, and silicon atoms in the layers, the chemical dry etch rates were enhanced significantly. The process regime for the etch rate enhancement of the layers was extended at elevated temperature

Element depth profiles of porous silicon

International Nuclear Information System (INIS)

Kobzev, A.P.; Nikonov, O.A.; Kulik, M.; Zuk, J.; Krzyzanowska, H.; Ochalski, T.J.

1997-01-01

Element depth profiles of porous silicon were measured on the Van-de-Graaff accelerator in the energy range of 4 He + ions from 2 to 3.2 MeV. Application of complementary RBS, ERD and 16 O(α,α) 16 O nuclear reaction methods permits us to obtain: 1) the exact silicon, oxygen and hydrogen distribution in the samples, 2) the distribution of partial pore concentrations. The oxygen concentration in porous silicon reaches 30%, which allows one to assume the presence of silicon oxide in the pores and to explain the spectrum shift of luminescence into the blue area

Corrosion resistance and cytocompatibility of biodegradable surgical magnesium alloy coated with hydrogenated amorphous silicon.

Science.gov (United States)

Xin, Yunchang; Jiang, Jiang; Huo, Kaifu; Tang, Guoyi; Tian, Xiubo; Chu, Paul K

2009-06-01

The fast degradation rates in the physiological environment constitute the main limitation for the applications of surgical magnesium alloys as biodegradable hard-tissue implants. In this work, a stable and dense hydrogenated amorphous silicon coating (a-Si:H) with desirable bioactivity is deposited on AZ91 magnesium alloy using magnetron sputtering deposition. Raman spectroscopy and Fourier transform infrared spectroscopy reveal that the coating is mainly composed of hydrogenated amorphous silicon. The hardness of the coated alloy is enhanced significantly and the coating is quite hydrophilic as well. Potentiodynamic polarization results show that the corrosion resistance of the coated alloy is enhanced dramatically. In addition, the deterioration process of the coating in simulated body fluids is systematically investigated by open circuit potential evolution and electrochemical impedance spectroscopy. The cytocompatibility of the coated Mg is evaluated for the first time using hFOB1.19 cells and favorable biocompatibility is observed. 2008 Wiley Periodicals, Inc.

Thermophysical spectroscopy of defect states in silicon

International Nuclear Information System (INIS)

Igamberdyev, Kh.T.; Mamadalimov, A.T.; Khabibullaev, P.K.

1989-01-01

The present work deals with analyzing the possibilities of using the non-traditional thermophysical methods to study a defect structure in silicon. For this purpose, the temperature dependences of thermophysical properties of defect silicon are investigated. A number of new, earlier unknown physical phenomena in silicon are obtained, and their interpretation has enabled one to establish the main physical mechanisms of formation of deep defect states in silicon

The effect of the MgO buffer layer thickness on magnetic anisotropy in MgO/Fe/Cr/MgO buffer/MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Kozioł-Rachwał, Anna, E-mail: a.koziolrachwal@aist.go.jp [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, Takayuki; Zayets, Vadym; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Suzuki, Yoshishige [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

2016-08-28

The relationship between the magnetic properties and MgO buffer layer thickness d was studied in epitaxial MgO/Fe(t)/Cr/MgO(d) layers grown on MgO(001) substrate in which the Fe thickness t ranged from 0.4 nm to 1.1 nm. For 0.4 nm ≤ t ≤ 0.7 nm, a non-monotonic coercivity dependence on the MgO buffer thickness was shown by perpendicular magneto-optic Kerr effect magnetometry. For thicker Fe films, an increase in the buffer layer thickness resulted in a spin reorientation transition from perpendicular to the in-plane magnetization direction. Possible origins of these unusual behaviors were discussed in terms of the suppression of carbon contamination at the Fe surface and changes in the magnetoelastic anisotropy in the system. These results illustrate a method to control magnetic anisotropy in MgO/Fe/Cr/MgO(d) via an appropriate choice of MgO buffer layer thickness d.

Evidence of localized amorphous silicon clustering from Raman depth-probing of silicon nanocrystals in fused silica

International Nuclear Information System (INIS)

Barba, D; Martin, F; Ross, G G

2008-01-01

Silicon nanocrystals (Si-nc) and amorphous silicon (α-Si) produced by silicon implantation in fused silica have been studied by micro-Raman spectroscopy. Information regarding the Raman signature of the α-Si phonon excitation was extracted from Raman depth-probing measurements using the phenomenological phonon confinement model. The spectral deconvolution of the Raman measurements recorded at different laser focusing depths takes into account both the Si-nc size variation and the Si-nc spatial distribution within the sample. The phonon peak associated with α-Si around 470 cm -1 is greatest for in-sample laser focusing, indicating that the formation of amorphous silicon is more important in the region containing a high concentration of silicon excess, where large Si-nc are located. As also observed for Si-nc systems prepared by SiO x layer deposition, this result demonstrates the presence of α-Si in high excess Si implanted Si-nc systems

Microstructural evolution in Mg-rich Mg-Zn-Y alloys

International Nuclear Information System (INIS)

Biswas, T.; Ranganathan, S.; Nair, S.; Bajargan, G.

2005-01-01

Mg-rich Mg-Zn-Y alloys with nominal compositions Mg 97 Zn 1 Y 2 , Mg 97 Zn 2 Y 1 , Mg 92 Zn 6.5 Y 1.5 and Mg 97-x Zn 1 Y 2 Zr x have been chosen for the present study. These alloys are prepared by using sand casting mold. The sand cast alloys are remelted and subjected to copper mold casting and melt spinning techniques. The effect of cooling rate on microstructures was studied. It is observed that the size of the precipitates decreases with an increase of cooling rate. The formation of nano precipitates results in higher strength of the alloy as compared to the conventional alloys. The microstructures of melt spun ribbons are compared with RS/PM (rapidly solidified power metallurgy) Mg 97 Zn 1 Y 2 alloy, obtained from a different source. (author)

Characterization of Czochralski silicon detectors

OpenAIRE

Luukka, Panja-Riina

2006-01-01

This thesis describes the characterization of irradiated and non-irradiated segmented detectors made of high-resistivity (>1 kΩcm) magnetic Czochralski (MCZ) silicon. It is shown that the radiation hardness (RH) of the protons of these detectors is higher than that of devices made of traditional materials such as Float Zone (FZ) silicon or Diffusion Oxygenated Float Zone (DOFZ) silicon due to the presence of intrinsic oxygen (> 5 × 1017 cm−3). The MCZ devices therefore present an interesting ...

Iron solubility in highly boron-doped silicon

International Nuclear Information System (INIS)

McHugo, S.A.; McDonald, R.J.; Smith, A.R.; Hurley, D.L.; Weber, E.R.

1998-01-01

We have directly measured the solubility of iron in high and low boron-doped silicon using instrumental neutron activation analysis. Iron solubilities were measured at 800, 900, 1000, and 1100thinsp degree C in silicon doped with either 1.5x10 19 or 6.5x10 14 thinspboronthinspatoms/cm 3 . We have measured a greater iron solubility in high boron-doped silicon as compared to low boron-doped silicon, however, the degree of enhancement is lower than anticipated at temperatures >800thinsp degree C. The decreased enhancement is explained by a shift in the iron donor energy level towards the valence band at elevated temperatures. Based on this data, we have calculated the position of the iron donor level in the silicon band gap at elevated temperatures. We incorporate the iron energy level shift in calculations of iron solubility in silicon over a wide range of temperatures and boron-doping levels, providing a means to accurately predict iron segregation between high and low boron-doped silicon. copyright 1998 American Institute of Physics

NetErosividade MG: erosividade da chuva em Minas Gerais NetErosividade MG: rainfall erosivity for Minas Gerais State, Brazil

Directory of Open Access Journals (Sweden)

Michel Castro Moreira

2008-06-01

Full Text Available A erosividade da chuva é um índice numérico que expressa a capacidade das chuvas em provocar erosão hídrica no solo. O presente trabalho teve por objetivo desenvolver um programa computacional para estimar os valores da erosividade da chuva no Estado de Minas Gerais com base em redes neurais artificiais (RNAs. O valor anual da erosividade da chuva é obtido pelo somatório dos valores mensais dos índices de erosividade EI30 ou KE > 25. Foram utilizados para cálculo de cada um desses índices dois métodos de obtenção da energia cinética de precipitação pluvial. Dessa maneira, obtiveram-se quatro valores de erosividade para cada mês, totalizando o desenvolvimento de 48 redes. As RNAs desenvolvidas foram implementadas no ambiente de programação Borland Delphi 7.0. O programa computacional desenvolvido foi denominado NetErosividade MG. O programa fornece, de forma fácil e rápida, os valores mensais e anual da erosividade da chuva para qualquer localidade do Estado de Minas Gerais.Rainfall erosivity represents the potential of rainfall causing soil erosion. This study aimed to develop a software to estimate rainfall erosivity in the state of Minas Gerais based on Artificial Neural Networks (ANNs. The annual value of the rainfall erosivity is given by the sum of the monthly values of the erosivity indexes EI30 or KE > 25. Two methodologies were used to estimate the kinetic energy for each index. Thus, four erosivity values were evaluated for each month, resulting in the development of 48 ANNs. These ANNs were implemented using the software Borland Delphi 7.0. The new software was called NetErosividade MG. The program calculates the monthly and annual values of rainfall erosivity for any location in the state of Minas Gerais in an easy and fast way.

Laser-beam-induced current mapping evaluation of porous silicon-based passivation in polycrystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Rabha, M. Ben; Bessais, B. [Laboratoire de Nanomateriaux et des Systemes pour l' Energie, Centre de Recherches et des Technologies de l' Energie - Technopole de Borj-Cedria BP 95, 2050 Hammam-Lif (Tunisia); Dimassi, W.; Bouaicha, M.; Ezzaouia, H. [Laboratoire de photovoltaique, des semiconducteurs et des nanostructures, Centre de Recherches et des Technologies de l' Energie - Technopole de Borj-Cedria BP 95, 2050 Hammam-Lif (Tunisia)

2009-05-15

In the present work, we report on the effect of introducing a superficial porous silicon (PS) layer on the performance of polycrystalline silicon (pc-Si) solar cells. Laser-beam-induced current (LBIC) mapping shows that the PS treatment on the emitter of pc-Si solar cells improves their quantum response and reduce the grain boundaries (GBs) activity. After the porous silicon treatment, mapping investigation shows an enhancement of the LBIC and the internal quantum efficiency (IQE), due to an improvement of the minority carrier diffusion length and the passivation of recombination centers at the GBs as compared to the reference substrate. It was quantitatively shown that porous silicon treatment can passivate both the grains and GBs. (author)

Implantation damage in silicon devices

International Nuclear Information System (INIS)

Nicholas, K.H.

1977-01-01

Ion implantation, is an attractive technique for producing doped layers in silicon devices but the implantation process involves disruption of the lattice and defects are formed, which can degrade device properties. Methods of minimizing such damage are discussed and direct comparisons made between implantation and diffusion techniques in terms of defects in the final devices and the electrical performance of the devices. Defects are produced in the silicon lattice during implantation but they are annealed to form secondary defects even at room temperature. The annealing can be at a low temperature ( 0 C) when migration of defects in silicon in generally small, or at high temperature when they can grow well beyond the implanted region. The defect structures can be complicated by impurity atoms knocked into the silicon from surface layers by the implantation. Defects can also be produced within layers on top of the silicon and these can be very important in device fabrication. In addition to affecting the electrical properties of the final device, defects produced during fabrication may influence the chemical properties of the materials. The use of these properties to improve devices are discussed as well as the degradation they can cause. (author)

Defects and impurities in silicon materials an introduction to atomic-level silicon engineering

CERN Document Server

Langouche, Guido

2015-01-01

This book emphasizes the importance of the fascinating atomistic insights into the defects and the impurities as well as the dynamic behaviors in silicon materials, which have become more directly accessible over the past 20 years. Such progress has been made possible by newly developed experimental methods, first principle theories, and computer simulation techniques. The book is aimed at young researchers, scientists, and technicians in related industries. The main purposes are to provide readers with 1) the basic physics behind defects in silicon materials, 2) the atomistic modeling as well as the characterization techniques related to defects and impurities in silicon materials, and 3) an overview of the wide range of the research fields involved.

Photonic integration and photonics-electronics convergence on silicon platform

CERN Document Server

Liu, Jifeng; Baba, Toshihiko; Vivien, Laurent; Xu, Dan-Xia

2015-01-01

Silicon photonics technology, which has the DNA of silicon electronics technology, promises to provide a compact photonic integration platform with high integration density, mass-producibility, and excellent cost performance. This technology has been used to develop and to integrate various photonic functions on silicon substrate. Moreover, photonics-electronics convergence based on silicon substrate is now being pursued. Thanks to these features, silicon photonics will have the potential to be a superior technology used in the construction of energy-efficient cost-effective apparatuses for various applications, such as communications, information processing, and sensing. Considering the material characteristics of silicon and difficulties in microfabrication technology, however, silicon by itself is not necessarily an ideal material. For example, silicon is not suitable for light emitting devices because it is an indirect transition material. The resolution and dynamic range of silicon-based interference de...

Combination of silicon nitride and porous silicon induced optoelectronic features enhancement of multicrystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Rabha, Mohamed Ben; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

2011-06-15

The effects of antireflection (ARC) and surface passivation films on optoelectronic features of multicrystalline silicon (mc-Si) were investigated in order to perform high efficiency solar cells. A double layer consisting of Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon nitride (SiN{sub x}) on porous silicon (PS) was achieved on mc-Si surfaces. It was found that this treatment decreases the total surface reflectivity from about 25% to around 6% in the 450-1100 nm wavelength range. As a result, the effective minority carrier diffusion length, estimated from the Laser-beam-induced current (LBIC) method, was found to increase from 312 {mu}m for PS-treated cells to about 798 {mu}m for SiN{sub x}/PS-treated ones. The deposition of SiN{sub x} was found to impressively enhance the minority carrier diffusion length probably due to hydrogen passivation of surface, grain boundaries and bulk defects. Fourier Transform Infrared Spectroscopy (FTIR) shows that the vibration modes of the highly suitable passivating Si-H bonds exhibit frequency shifts toward higher wavenumber, depending on the x ratio of the introduced N atoms neighbors. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Selected Silicon Carbide Reports from Rutgers Materials Center of Excellence Annual Reports, 2010-2011

Science.gov (United States)

2015-03-01

function of eiej and taking the second energy derivative with respect to ei and ej. The hydrostatic pressure is obtained by calculating the change...presence of unreacted Si and C, as well as magnesium (Mg), Al, calcium (Ca), titanium (Ti), vanadium (V), iron (Fe), and zirconium (Zr) impurities

Microstructure and Properties of AlSi10Mg Powder for Selective Laser Melting

Directory of Open Access Journals (Sweden)

TANG Pengjun

2018-02-01

Full Text Available The AlSi10Mg powder was prepared by supersonic gas atomization. After classified, the powder was fabricated into block by selective laser melting (SLM. The microstructure, phase, and evolutions of powder and block were investigated by optical microscope, scanning electron microscope and X-Ray Diffraction. The tensile properties of SLM block were tested by tensile experiments at room temperature. The results show that the size distribution of AlSi10Mg powder after classified can meet the requirements of SLM technology. The powder always is spherical and spherical-like. Meanwhile, the microstructure of powders is fine and uniform, which contain α(Al matrix and (α+Si eutectic. In addition, the melt pool boundaries of SLM block are legible. The microstructure is also uniform and densified, the relative density approaches to 99.5%. On the other hand, only α(Al and few Silicon phase are detected in this condition, due to the most alloying elements are dissolved in α(Al matrix. At room temperature, the ultimate tensile strength of SLM block reaches up to 442 MPa.

InP membrane on silicon integration technology

NARCIS (Netherlands)

Smit, M.K.

2013-01-01

Integration of light sources in silicon photonics is usually done with an active InP-based layer stack on a silicon-based photonic circuit-layer. InP Membrane On Silicon (IMOS) technology integrates all functionality in a single InP-based layer.

Simulation of atomistic processes during silicon oxidation

OpenAIRE

Bongiorno, Angelo

2003-01-01

Silicon dioxide (SiO2) films grown on silicon monocrystal (Si) substrates form the gate oxides in current Si-based microelectronics devices. The understanding at the atomic scale of both the silicon oxidation process and the properties of the Si(100)-SiO2 interface is of significant importance in state-of-the-art silicon microelectronics manufacturing. These two topics are intimately coupled and are both addressed in this theoretical investigation mainly through first-principles calculations....

Silicon nitride-fabrication, forming and properties

International Nuclear Information System (INIS)

Yehezkel, O.

1983-01-01

This article, which is a literature survey of the recent years, includes description of several methods for the formation of silicone nitride, and five methods of forming: Reaction-bonded silicon nitride, sintering, hot pressing, hot isostatic pressing and chemical vapour deposition. Herein are also included data about mechanical and physical properties of silicon nitride and the relationship between the forming method and the properties. (author)

Porous silicon technology for integrated microsystems

Science.gov (United States)

Wallner, Jin Zheng

With the development of micro systems, there is an increasing demand for integrable porous materials. In addition to those conventional applications, such as filtration, wicking, and insulating, many new micro devices, including micro reactors, sensors, actuators, and optical components, can benefit from porous materials. Conventional porous materials, such as ceramics and polymers, however, cannot meet the challenges posed by micro systems, due to their incompatibility with standard micro-fabrication processes. In an effort to produce porous materials that can be used in micro systems, porous silicon (PS) generated by anodization of single crystalline silicon has been investigated. In this work, the PS formation process has been extensively studied and characterized as a function of substrate type, crystal orientation, doping concentration, current density and surfactant concentration and type. Anodization conditions have been optimized for producing very thick porous silicon layers with uniform pore size, and for obtaining ideal pore morphologies. Three different types of porous silicon materials: meso porous silicon, macro porous silicon with straight pores, and macro porous silicon with tortuous pores, have been successfully produced. Regular pore arrays with controllable pore size in the range of 2mum to 6mum have been demonstrated as well. Localized PS formation has been achieved by using oxide/nitride/polysilicon stack as masking materials, which can withstand anodization in hydrofluoric acid up to twenty hours. A special etching cell with electrolytic liquid backside contact along with two process flows has been developed to enable the fabrication of thick macro porous silicon membranes with though wafer pores. For device assembly, Si-Au and In-Au bonding technologies have been developed. Very low bonding temperature (˜200°C) and thick/soft bonding layers (˜6mum) have been achieved by In-Au bonding technology, which is able to compensate the potentially

Lifetime of Nano-Structured Black Silicon for Photovoltaic Applications

DEFF Research Database (Denmark)

Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

2016-01-01

In this work, we present recent results of lifetime optimization for nano-structured black silicon and its photovoltaic applications. Black silicon nano-structures provide significant reduction of silicon surface reflection due to highly corrugated nanostructures with excellent light trapping pro......, respectively. This is promising for use of black silicon RIE nano-structuring in a solar cell process flow......In this work, we present recent results of lifetime optimization for nano-structured black silicon and its photovoltaic applications. Black silicon nano-structures provide significant reduction of silicon surface reflection due to highly corrugated nanostructures with excellent light trapping...

Silicon (100)/SiO2 by XPS

Energy Technology Data Exchange (ETDEWEB)

Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

2013-09-25

Silicon (100) wafers are ubiquitous in microfabrication and, accordingly, their surface characteristics are important. Herein, we report the analysis of Si (100) via X-ray photoelectron spectroscopy (XPS) using monochromatic Al K radiation. Survey scans show that the material is primarily silicon and oxygen, and the Si 2p region shows two peaks that correspond to elemental silicon and silicon dioxide. Using these peaks the thickness of the native oxide (SiO2) was estimated using the equation of Strohmeier.1 The oxygen peak is symmetric. The material shows small amounts of carbon, fluorine, and nitrogen contamination. These silicon wafers are used as the base material for subsequent growth of templated carbon nanotubes.

Microstructure and mechanical properties of silicon nitride structural ceramics of silicon nitride

International Nuclear Information System (INIS)

Strohaecker, T.R.; Nobrega, M.C.S.

1989-01-01

The utilization of direct evaluation technic of tenacity for fracturing by hardness impact in silicon nitride ceramics is described. The microstructure were analysied, by Scanning Electron Microscopy, equiped with a microanalysis acessory by X ray energy dispersion. The difference between the values of K IC measure for two silicon nitride ceramics is discussed, in function of the microstructures and the fracture surfaces of the samples studied. (C.G.C.) [pt

Formation and photoluminescence of "Cauliflower" silicon nanoparticles

NARCIS (Netherlands)

Tang, W.; Eilers, J.J.; Huis, van M.A.; Wang, D.; Schropp, R.E.I.; Vece, Di M.

2015-01-01

The technological advantages of silicon make silicon nanoparticles, which can be used as quantum dots in a tandem configuration, highly relevant for photovoltaics. However, producing a silicon quantum dot solar cell structure remains a challenge. Here we use a gas aggregation cluster source to

The LHCb Silicon Tracker

Energy Technology Data Exchange (ETDEWEB)

Tobin, Mark, E-mail: Mark.Tobin@epfl.ch

2016-09-21

The LHCb experiment is dedicated to the study of heavy flavour physics at the Large Hadron Collider (LHC). The primary goal of the experiment is to search for indirect evidence of new physics via measurements of CP violation and rare decays of beauty and charm hadrons. The LHCb detector has a large-area silicon micro-strip detector located upstream of a dipole magnet, and three tracking stations with silicon micro-strip detectors in the innermost region downstream of the magnet. These two sub-detectors form the LHCb Silicon Tracker (ST). This paper gives an overview of the performance and operation of the ST during LHC Run 1. Measurements of the observed radiation damage are shown and compared to the expectation from simulation.

Demonstration of slot-waveguide structures on silicon nitride / silicon oxide platform.

Science.gov (United States)

Barrios, C A; Sánchez, B; Gylfason, K B; Griol, A; Sohlström, H; Holgado, M; Casquel, R

2007-05-28

We report on the first demonstration of guiding light in vertical slot-waveguides on silicon nitride/silicon oxide material system. Integrated ring resonators and Fabry-Perot cavities have been fabricated and characterized in order to determine optical features of the slot-waveguides. Group index behavior evidences guiding and confinement in the low-index slot region at O-band (1260-1370nm) telecommunication wavelengths. Propagation losses of <20 dB/cm have been measured for the transverse-electric mode of the slot-waveguides.

Suppression of interfacial voids formation during silane (SiH4)-based silicon oxide bonding with a thin silicon nitride capping layer

Science.gov (United States)

Lee, Kwang Hong; Bao, Shuyu; Wang, Yue; Fitzgerald, Eugene A.; Seng Tan, Chuan

2018-01-01

The material properties and bonding behavior of silane-based silicon oxide layers deposited by plasma-enhanced chemical vapor deposition were investigated. Fourier transform infrared spectroscopy was employed to determine the chemical composition of the silicon oxide films. The incorporation of hydroxyl (-OH) groups and moisture absorption demonstrates a strong correlation with the storage duration for both as-deposited and annealed silicon oxide films. It is observed that moisture absorption is prevalent in the silane-based silicon oxide film due to its porous nature. The incorporation of -OH groups and moisture absorption in the silicon oxide films increase with the storage time (even in clean-room environments) for both as-deposited and annealed silicon oxide films. Due to silanol condensation and silicon oxidation reactions that take place at the bonding interface and in the bulk silicon, hydrogen (a byproduct of these reactions) is released and diffused towards the bonding interface. The trapped hydrogen forms voids over time. Additionally, the absorbed moisture could evaporate during the post-bond annealing of the bonded wafer pair. As a consequence, defects, such as voids, form at the bonding interface. To address the problem, a thin silicon nitride capping film was deposited on the silicon oxide layer before bonding to serve as a diffusion barrier to prevent moisture absorption and incorporation of -OH groups from the ambient. This process results in defect-free bonded wafers.

MOS structures containing silicon nanoparticles for memory device applications

International Nuclear Information System (INIS)

Nedev, N; Zlatev, R; Nesheva, D; Manolov, E; Levi, Z; Brueggemann, R; Meier, S

2008-01-01

Metal-oxide-silicon structures containing layers with amorphous or crystalline silicon nanoparticles in a silicon oxide matrix are fabricated by sequential physical vapour deposition of SiO x (x = 1.15) and RF sputtering of SiO 2 on n-type crystalline silicon, followed by high temperature annealing in an inert gas ambient. Depending on the annealing temperature, 700 deg. C or 1000 deg. C, amorphous or crystalline silicon nanoparticles are formed in the silicon oxide matrix. The annealing process is used not only for growing nanoparticles but also to form a dielectric layer with tunnelling thickness at the silicon/insulator interface. High frequency C-V measurements demonstrate that both types of structures can be charged negatively or positively by applying a positive or negative voltage on the gate. The structures with amorphous silicon nanoparticles show several important advantages compared to the nanocrystal ones, such as lower defect density at the interface between the crystalline silicon wafer and the tunnel silicon oxide, better retention characteristics and better reliability

Formation of iron disilicide on amorphous silicon

Science.gov (United States)

Erlesand, U.; Östling, M.; Bodén, K.

1991-11-01

Thin films of iron disilicide, β-FeSi 2 were formed on both amorphous silicon and on crystalline silicon. The β-phase is reported to be semiconducting with a direct band-gap of about 0.85-0.89 eV. This phase is known to form via a nucleation-controlled growth process on crystalline silicon and as a consequence a rather rough silicon/silicide interface is usually formed. In order to improve the interface a bilayer structure of amorphous silicon and iron was sequentially deposited on Czochralski silicon in an e-gun evaporation system. Secondary ion mass spectrometry profiling (SIMS) and scanning electron micrographs revealed an improvement of the interface sharpness. Rutherford backscattering spectrometry (RBS) and X-ray diffractiometry showed β-FeSi 2 formation already at 525°C. It was also observed that the silicide growth was diffusion-controlled, similar to what has been reported for example in the formation of NiSi 2 for the reaction of nickel on amorphous silicon. The kinetics of the FeSi 2 formation in the temperature range 525-625°C was studied by RBS and the activation energy was found to be 1.5 ± 0.1 eV.

Metallization of DNA on silicon surface

International Nuclear Information System (INIS)

Puchkova, Anastasiya Olegovna; Sokolov, Petr; Petrov, Yuri Vladimirovich; Kasyanenko, Nina Anatolievna

2011-01-01

New simple way for silver deoxyribonucleic acid (DNA)-based nanowires preparation on silicon surface was developed. The electrochemical reduction of silver ions fixed on DNA molecule provides the forming of tightly matched zonate silver clusters. Highly homogeneous metallic clusters have a size about 30 nm. So the thickness of nanowires does not exceed 30–50 nm. The surface of n-type silicon monocrystal is the most convenient substrate for this procedure. The comparative analysis of DNA metallization on of n-type silicon with a similar way for nanowires fabrication on p-type silicon, freshly cleaved mica, and glass surface shows the advantage of n-type silicon, which is not only the substrate for DNA fixation but also the source of electrons for silver reduction. Images of bound DNA molecules and fabricated nanowires have been obtained using an atomic force microscope and a scanning ion helium microscope. DNA interaction with silver ions in a solution was examined by the methods of ultraviolet spectroscopy and circular dichroism.

Stretchable and foldable silicon-based electronics

KAUST Repository

Cavazos Sepulveda, Adrian Cesar

2017-03-30

Flexible and stretchable semiconducting substrates provide the foundation for novel electronic applications. Usually, ultra-thin, flexible but often fragile substrates are used in such applications. Here, we describe flexible, stretchable, and foldable 500-μm-thick bulk mono-crystalline silicon (100) “islands” that are interconnected via extremely compliant 30-μm-thick connectors made of silicon. The thick mono-crystalline segments create a stand-alone silicon array that is capable of bending to a radius of 130 μm. The bending radius of the array does not depend on the overall substrate thickness because the ultra-flexible silicon connectors are patterned. We use fracture propagation to release the islands. Because they allow for three-dimensional monolithic stacking of integrated circuits or other electronics without any through-silicon vias, our mono-crystalline islands can be used as a “more-than-Moore” strategy and to develop wearable electronics that are sufficiently robust to be compatible with flip-chip bonding.

Stretchable and foldable silicon-based electronics

KAUST Repository

Cavazos Sepulveda, Adrian Cesar; Diaz Cordero, M. S.; Carreno, Armando Arpys Arevalo; Nassar, Joanna M.; Hussain, Muhammad Mustafa

2017-01-01

Flexible and stretchable semiconducting substrates provide the foundation for novel electronic applications. Usually, ultra-thin, flexible but often fragile substrates are used in such applications. Here, we describe flexible, stretchable, and foldable 500-μm-thick bulk mono-crystalline silicon (100) “islands” that are interconnected via extremely compliant 30-μm-thick connectors made of silicon. The thick mono-crystalline segments create a stand-alone silicon array that is capable of bending to a radius of 130 μm. The bending radius of the array does not depend on the overall substrate thickness because the ultra-flexible silicon connectors are patterned. We use fracture propagation to release the islands. Because they allow for three-dimensional monolithic stacking of integrated circuits or other electronics without any through-silicon vias, our mono-crystalline islands can be used as a “more-than-Moore” strategy and to develop wearable electronics that are sufficiently robust to be compatible with flip-chip bonding.

Numerical Simulation Of Silicon-Ribbon Growth

Science.gov (United States)

Woda, Ben K.; Kuo, Chin-Po; Utku, Senol; Ray, Sujit Kumar

1987-01-01

Mathematical model includes nonlinear effects. In development simulates growth of silicon ribbon from melt. Takes account of entire temperature and stress history of ribbon. Numerical simulations performed with new model helps in search for temperature distribution, pulling speed, and other conditions favoring growth of wide, flat, relatively defect-free silicon ribbons for solar photovoltaic cells at economically attractive, high production rates. Also applicable to materials other than silicon.

Ion beam figuring of silicon aspheres

Science.gov (United States)

Demmler, Marcel; Zeuner, Michael; Luca, Alfonz; Dunger, Thoralf; Rost, Dirk; Kiontke, Sven; Krüger, Marcus

2011-03-01

Silicon lenses are widely used for infrared applications. Especially for portable devices the size and weight of the optical system are very important factors. The use of aspherical silicon lenses instead of spherical silicon lenses results in a significant reduction of weight and size. The manufacture of silicon lenses is more challenging than the manufacture of standard glass lenses. Typically conventional methods like diamond turning, grinding and polishing are used. However, due to the high hardness of silicon, diamond turning is very difficult and requires a lot of experience. To achieve surfaces of a high quality a polishing step is mandatory within the manufacturing process. Nevertheless, the required surface form accuracy cannot be achieved through the use of conventional polishing methods because of the unpredictable behavior of the polishing tools, which leads to an unstable removal rate. To overcome these disadvantages a method called Ion Beam Figuring can be used to manufacture silicon lenses with high surface form accuracies. The general advantage of the Ion Beam Figuring technology is a contactless polishing process without any aging effects of the tool. Due to this an excellent stability of the removal rate without any mechanical surface damage is achieved. The related physical process - called sputtering - can be applied to any material and is therefore also applicable to materials of high hardness like Silicon (SiC, WC). The process is realized through the commercially available ion beam figuring system IonScan 3D. During the process, the substrate is moved in front of a focused broad ion beam. The local milling rate is controlled via a modulated velocity profile, which is calculated specifically for each surface topology in order to mill the material at the associated positions to the target geometry. The authors will present aspherical silicon lenses with very high surface form accuracies compared to conventionally manufactured lenses.

Vibrational modes of porous silicon

International Nuclear Information System (INIS)

Sabra, M.; Naddaf, M.

2012-01-01

On the basis of theoretical and experimental investigations, the origin of room temperature photoluminescence (PL) from porous silicon is found to related to chemical complexes constituted the surface, in particular, SiHx, SiOx and SiOH groups. Ab initio atomic and molecular electronic structure calculations on select siloxane compounds were used for imitation of infrared (IR) spectra of porous silicon. These are compared to the IR spectra of porous silicon recorded by using Fourier Transform Infrared Spectroscopy (FTIR). In contrast to linear siloxane, the suggested circular siloxane terminated with linear siloxane structure is found to well-imitate the experimental spectra. These results are augmented with EDX (energy dispersive x-ray spectroscopy) measurements, which showed that the increase of SiOx content in porous silicon due to rapid oxidation process results in considerable decrease in PL peak intensity and a blue shift in the peak position. (author)

Self-diffusion in single crystalline silicon nanowires

Science.gov (United States)

Südkamp, T.; Hamdana, G.; Descoins, M.; Mangelinck, D.; Wasisto, H. S.; Peiner, E.; Bracht, H.

2018-04-01

Self-diffusion experiments in single crystalline isotopically controlled silicon nanowires with diameters of 70 and 400 nm at 850 and 1000 °C are reported. The isotope structures were first epitaxially grown on top of silicon substrate wafers. Nanowires were subsequently fabricated using a nanosphere lithography process in combination with inductively coupled plasma dry reactive ion etching. Three-dimensional profiling of the nanosized structure before and after diffusion annealing was performed by means of atom probe tomography (APT). Self-diffusion profiles obtained from APT analyses are accurately described by Fick's law for self-diffusion. Data obtained for silicon self-diffusion in nanowires are equal to the results reported for bulk silicon crystals, i.e., finite size effects and high surface-to-volume ratios do not significantly affect silicon self-diffusion. This shows that the properties of native point defects determined from self-diffusion in bulk crystals also hold for nanosized silicon structures with diameters down to 70 nm.

Transport properties of hydrogen passivated silicon nanotubes and silicon nanotube field effect transistors

KAUST Repository

Montes Muñoz, Enrique

2017-01-24

We investigate the electronic transport properties of silicon nanotubes attached to metallic electrodes from first principles, using density functional theory and the non-equilibrium Green\\'s function method. The influence of the surface termination is studied as well as the dependence of the transport characteristics on the chirality, diameter, and length. Strong electronic coupling between nanotubes and electrodes is found to be a general feature that results in low contact resistance. The conductance in the tunneling regime is discussed in terms of the complex band structure. Silicon nanotube field effect transistors are simulated by applying a uniform potential gate. Our results demonstrate very high values of transconductance, outperforming the best commercial silicon field effect transistors, combined with low values of sub-threshold swing.

Photovoltaic Programme Edition 2007. Summary Report, Project List, Annual Project Reports 2006 (Abstracts)

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01