Sample records for aastaks silicon valleysse

  1. Silicon nitride/silicon carbide composite powders

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-06-11

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  2. Gluing silicon with silicone

    NASA Astrophysics Data System (ADS)

    Abt, I.; Fox, H.; Moshous, B.; Richter, R. H.; Riechmann, K.; Rietz, M.; Riedl, J.; Denis, R. St; Wagner, W.

    1998-02-01

    Problems and solutions concerning the gluing of silicon detectors are discussed. The R & D work for the HERA- B vertex detector system led to gluing studies with epoxy and silicone-based adhesives used on ceramics and carbon fibre. The HERA- B solution using a silicone glue is presented.

  3. Method and apparatus for stable silicon dioxide layers on silicon grown in silicon nitride ambient

    NASA Technical Reports Server (NTRS)

    Cohen, R. A.; Wheeler, R. K. (Inventor)

    1974-01-01

    A method and apparatus for thermally growing stable silicon dioxide layers on silicon is disclosed. A previously etched and baked silicon nitride tube placed in a furnace is used to grow the silicon dioxide. First, pure oxygen is allowed to flow through the tube to initially coat the inside surface of the tube with a thin layer of silicon dioxide. After the tube is coated with the thin layer of silicon dioxide, the silicon is oxidized thermally in a normal fashion. If the tube becomes contaminated, the silicon dioxide is etched off thereby exposing clean silicon nitride and then the inside of the tube is recoated with silicon dioxide. As is disclosed, the silicon nitride tube can also be used as the ambient for the pyrolytic decomposition of silane and ammonia to form thin layers of clean silicon nitride.

  4. Silicon surface passivation by silicon nitride deposition

    NASA Technical Reports Server (NTRS)

    Olsen, L. C.

    1984-01-01

    Silicon nitride deposition was studied as a method of passivation for silicon solar cell surfaces. The following three objectives were the thrust of the research: (1) the use of pecvd silicon nitride for passivation of silicon surfaces; (2) measurement techniques for surface recombination velocity; and (3) the importance of surface passivation to high efficiency solar cells.

  5. Method for producing silicon nitride/silicon carbide composite

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-07-23

    Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.

  6. Silicone metalization

    DOEpatents

    Maghribi, Mariam N [Livermore, CA; Krulevitch, Peter [Pleasanton, CA; Hamilton, Julie [Tracy, CA

    2006-12-05

    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.

  7. Silicone metalization

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Production of electronic grade lunar silicon by disproportionation of silicon difluoride

    NASA Technical Reports Server (NTRS)

    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.

  10. Method of making silicon carbide-silicon composite having improved oxidation resistance

    NASA Technical Reports Server (NTRS)

    Wang, Hongyu (Inventor); Luthra, Krishan Lal (Inventor)

    2002-01-01

    A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

  11. Solar silicon from directional solidification of MG silicon produced via the silicon carbide route

    NASA Technical Reports Server (NTRS)

    Rustioni, M.; Margadonna, D.; Pirazzi, R.; Pizzini, S.

    1986-01-01

    A process of metallurgical grade (MG) silicon production is presented which appears particularly suitable for photovoltaic (PV) applications. The MG silicon is prepared in a 240 KVA, three electrode submerged arc furnace, starting from high grade quartz and high purity silicon carbide. The silicon smelted from the arc furnace was shown to be sufficiently pure to be directionally solidified to 10 to 15 kg. After grinding and acid leaching, had a material yield larger than 90%. With a MG silicon feedstock containing 3 ppmw B, 290 ppmw Fe, 190 ppmw Ti, and 170 ppmw Al, blended with 50% of off grade electronic grade (EG) silicon to reconduct the boron content to a concentration acceptable for solar cell fabrication, the 99% of deep level impurities were concentrated in the last 5% of the ingot. Quite remarkably this material has OCV values higher tham 540 mV and no appreciable shorts due to SiC particles.

  12. Colloidal characterization of ultrafine silicon carbide and silicon nitride powders

    NASA Technical Reports Server (NTRS)

    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.

  13. Develop Silicone Encapsulation Systems for Terrestrial Silicon Solar Arrays

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The results for Task 3 of the Low Cost Solar Array Project are presented. Task 3 is directed toward the development of a cost effective encapsulating system for photovoltaic modules using silicon based materials. The technical approach of the contract effort is divided into four special tasks: (1) technology review; (2) generation of concepts for screening and processing silicon encapsulation systems; (3) assessment of encapsulation concepts; and (4) evaluation of encapsulation concepts. The candidate silicon materials are reviewed. The silicon and modified silicon resins were chosen on the basis of similarity to materials with known weatherability, cost, initial tangential modulus, accelerated dirt pick-up test results and the ratio of the content of organic phenyl substitution of methyl substitution on the backbone of the silicon resin.

  14. Laser-induced amorphization of silicon during pulsed-laser irradiation of TiN/Ti/polycrystalline silicon/SiO2/silicon

    NASA Astrophysics Data System (ADS)

    Chong, Y. F.; Pey, K. L.; Wee, A. T. S.; Thompson, M. O.; Tung, C. H.; See, A.

    2002-11-01

    In this letter, we report on the complex solidification structures formed during laser irradiation of a titanium nitride/titanium/polycrystalline silicon/silicon dioxide/silicon film stack. Due to enhanced optical coupling, the titanium nitride/titanium capping layer increases the melt depth of polycrystalline silicon by more than a factor of 2. It is found that the titanium atoms diffuse through the entire polycrystalline silicon layer during irradiation. Contrary to the expected polycrystalline silicon growth, distinct regions of polycrystalline and amorphous silicon are formed instead. Possible mechanisms for the formation of these microstructures are proposed.

  15. Study on Silicon Microstructure Processing Technology Based on Porous Silicon

    NASA Astrophysics Data System (ADS)

    Shang, Yingqi; Zhang, Linchao; Qi, Hong; Wu, Yalin; Zhang, Yan; Chen, Jing

    2018-03-01

    Aiming at the heterogeneity of micro - sealed cavity in silicon microstructure processing technology, the technique of preparing micro - sealed cavity of porous silicon is proposed. The effects of different solutions, different substrate doping concentrations, different current densities, and different etching times on the rate, porosity, thickness and morphology of the prepared porous silicon were studied. The porous silicon was prepared by different process parameters and the prepared porous silicon was tested and analyzed. For the test results, optimize the process parameters and experiments. The experimental results show that the porous silicon can be controlled by optimizing the parameters of the etching solution and the doping concentration of the substrate, and the preparation of porous silicon with different porosity can be realized by different doping concentration, so as to realize the preparation of silicon micro-sealed cavity, to solve the sensor sensitive micro-sealed cavity structure heterogeneous problem, greatly increasing the application of the sensor.

  16. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOEpatents

    Corman, Gregory Scot; Luthra, Krishan Lal

    2002-01-01

    A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  17. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOEpatents

    Corman, Gregory Scot; Luthra, Krishan Lal

    1999-01-01

    A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  18. Silicon nitride/silicon carbide composite densified materials prepared using composite powders

    DOEpatents

    Dunmead, S.D.; Weimer, A.W.; Carroll, D.F.; Eisman, G.A.; Cochran, G.A.; Susnitzky, D.W.; Beaman, D.R.; Nilsen, K.J.

    1997-07-01

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  19. Silicon carbide-silicon composite having improved oxidation resistance and method of making

    NASA Technical Reports Server (NTRS)

    Wang, Hongyu (Inventor); Luthra, Krishan Lal (Inventor)

    1999-01-01

    A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

  20. Polycrystalline silicon study: Low-cost silicon refining technology prospects and semiconductor-grade polycrystalline silicon availability through 1988

    NASA Technical Reports Server (NTRS)

    Costogue, E. N.; Ferber, R.; Lutwack, R.; Lorenz, J. H.; Pellin, R.

    1984-01-01

    Photovoltaic arrays that convert solar energy into electrical energy can become a cost effective bulk energy generation alternative, provided that an adequate supply of low cost materials is available. One of the key requirements for economic photovoltaic cells is reasonably priced silicon. At present, the photovoltaic industry is dependent upon polycrystalline silicon refined by the Siemens process primarily for integrated circuits, power devices, and discrete semiconductor devices. This dependency is expected to continue until the DOE sponsored low cost silicon refining technology developments have matured to the point where they are in commercial use. The photovoltaic industry can then develop its own source of supply. Silicon material availability and market pricing projections through 1988 are updated based on data collected early in 1984. The silicon refining industry plans to meet the increasing demands of the semiconductor device and photovoltaic product industries are overviewed. In addition, the DOE sponsored technology research for producing low cost polycrystalline silicon, probabilistic cost analysis for the two most promising production processes for achieving the DOE cost goals, and the impacts of the DOE photovoltaics program silicon refining research upon the commercial polycrystalline silicon refining industry are addressed.

  1. Glass-silicon column

    DOEpatents

    Yu, Conrad M.

    2003-12-30

    A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

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

    PubMed

    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).

  3. Purified silicon production system

    DOEpatents

    Wang, Tihu; Ciszek, Theodore F.

    2004-03-30

    Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

  4. Electrical leakage phenomenon in heteroepitaxial cubic silicon carbide on silicon

    NASA Astrophysics Data System (ADS)

    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.

  5. Low cost silicon solar array project silicon materials task

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A program was established to develop a high temperature silicon production process using existing electric arc heater technology. Silicon tetrachloride and a reductant will be injected into an arc heated mixture of hydrogen and argon. Under these high temperature conditions, a very rapid reaction is expected to occur and proceed essentially to completion, yielding silicon and gaseous sodium chloride. Techniques for high temperature separation and collection of the molten silicon will be developed using standard engineering approaches, and the salt vapor will later be electrolytically separated into its elemental constituents for recycle. Preliminary technical evaluations and economic projections indicate not only that this process appears to be feasible, but that it also has the advantages of rapid, high capacity production of good quality molten silicon at a nominal cost.

  6. Buried oxide layer in silicon

    DOEpatents

    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.

  7. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boccard, Mathieu; Holman, Zachary C.

    Amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphous silicon carbide beingmore » shown to surpass amorphous silicon for temperatures above 300 °C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.« less

  8. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boccard, Mathieu; Holman, Zachary C.

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphousmore » silicon carbide being shown to surpass amorphous silicon for temperatures above 300°C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.« less

  9. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    DOE PAGES

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphousmore » silicon carbide being shown to surpass amorphous silicon for temperatures above 300°C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.« less

  10. Nonlinear silicon photonics

    NASA Astrophysics Data System (ADS)

    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.

  11. Compounding with Silicones.

    PubMed

    Allen, Loyd V

    2015-01-01

    Since the 1940s, methylchlorosilanes have been used to treat glassware to prevent blood from clotting. The use of silicones in pharmaceutical and medical applications has grown to where today they are used in many life-saving devices (pacemakers, hydrocephalic shunts) and pharmaceutical applications from tubing, to excipients in topical formulations, to adhesives to affix transdermal drug delivery systems, and are also being used in products as active pharmaceutical ingredients, such as antiflatulents. About 60% of today's skin-care products now contain some type of silicone where they are considered safe and are known to provide a pleasant "silky-touch," non-greasy, and non-staining feel. Silicones exhibit many useful characteristics, and the safety of these agents supports their numerous applications; their biocompatibility is partially due to their low-chemical reactivity displayed by silicones, low-surface energy, and their hydrophobicity. Silicones are used both as active ingredients and as excipients. In addition is their use for "siliconization," or surface treatment, of many parenteral packaging components. Dimethicone and silicone oil are used as lubricants on stoppers to aid machineability, in syringes to aid piston movement, or on syringe needles to reduce pain upon injection. Silicones are also useful in pharmaceutical compounding as is discussed in this artiele included with this article are in developing formulations with silicones.

  12. Silicon entering through silicon utilizing organisms has biological effects in human beings

    NASA Astrophysics Data System (ADS)

    Shraddhamayananda, S.

    2012-12-01

    Except in the lungs, there is no evidence that silicon can do any harm in our body and Silicon is as essential as magnesium and calcium for us. It helps in proper activities of the bone tissues and all of the components in the human skeletal system. It can prevent osteoporosis in bones and also helps in lowering of blood pressure. Silicon can also inhibit fungal disease by physically inhibiting fungal germ tube penetration of the epidermis. Many of our foods which are associated with silicon utilizing organisms like rice, vegetables, wheat etc, contain plenty silicon, however, during processing most silicon get lost. In alternative medicine silicon is used to promote expulsion of foreign bodies from tissue, in formation of suppuration and finally expulsion of pus from abscesses. Silicon is also used to remove fibrotic lesions and scar tissue and in this way it can prevent formation of keloids. Sometimes it is also used to treat chronic otitis media, and chronic fistula,

  13. Fabrication and characterization of silicon quantum dots in Si-rich silicon carbide films.

    PubMed

    Chang, Geng-Rong; Ma, Fei; Ma, Dayan; Xu, Kewei

    2011-12-01

    Amorphous Si-rich silicon carbide films were prepared by magnetron co-sputtering and subsequently annealed at 900-1100 degrees C. After annealing at 1100 degrees C, this configuration of silicon quantum dots embedded in amorphous silicon carbide formed. X-ray photoelectron spectroscopy was used to study the chemical modulation of the films. The formation and orientation of silicon quantum dots were characterized by glancing angle X-ray diffraction, which shows that the ratio of silicon and carbon significantly influences the species of quantum dots. High-resolution transmission electron microscopy investigations directly demonstrated that the formation of silicon quantum dots is heavily dependent on the annealing temperatures and the ratio of silicon and carbide. Only the temperature of about 1100 degrees C is enough for the formation of high-density and small-size silicon quantum dots due to phase separation and thermal crystallization. Deconvolution of the first order Raman spectra shows the existence of a lower frequency peak in the range 500-505 cm(-1) corresponding to silicon quantum dots with different atom ratio of silicon and carbon.

  14. Crystalline silicon growth in nickel/a-silicon bilayer

    NASA Astrophysics Data System (ADS)

    Mohiddon, Md Ahamad; Naidu, K. Lakshun; Dalba, G.; Rocca, F.; Krishna, M. Ghanashyam

    2013-02-01

    The effect of substrate temperature on amorphous Silicon crystallization, mediated by metal impurity is reported. Bilayers of Ni(200nm)/Si(400nm) are deposited on fused silica substrate by electron beam evaporator at 200 and 500 °C. Raman mapping shows that, 2 to 5 micron size crystalline silicon clusters are distributed over the entire surface of the sample. X-ray diffraction and X-ray absorption spectroscopy studies demonstrate silicon crystallizes over the metal silicide seeds and grow with the annealing temperature.

  15. Nonlinear silicon photonics

    NASA Astrophysics Data System (ADS)

    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.

  16. Silicon micro-mold

    DOEpatents

    Morales, Alfredo M [Livermore, CA

    2006-10-24

    The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

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

    PubMed

    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.

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

    PubMed Central

    König, 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-diffusion, statistics of small numbers, quantum- or dielectric confinement. In analogy to the concept of modulation doping, originally invented for III-V semiconductors, we demonstrate a heterostructure modulation doping method for silicon. Our approach utilizes a specific acceptor state of aluminium atoms in silicon dioxide to generate holes as majority carriers in adjacent silicon. By relocating the dopants from silicon to silicon dioxide, Si nanoscale doping problems are circumvented. In addition, the concept of aluminium-induced acceptor states for passivating hole selective tunnelling contacts as required for high-efficiency photovoltaics is presented and corroborated by first carrier lifetime and tunnelling current measurements. PMID:28425460

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

    PubMed

    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

  20. Silicon-on-Insulator Pin Diodes.

    DTIC Science & Technology

    1987-12-01

    Thin (0.5 Micron) Silicon-on-Oxidized Silicon Fig. 2.8 SEM Photographs of CVD Silicon Dioxide on Aluminum 28 After 1500 0 C Anneal in Oxygen...silicon nitride over the silicon dioxide encapsu- -9- lation layer and by depositing the silicon dioxide with a plasma CVD process which uses N20 as...relief via thermal expansion matching varies lin- -27- A B Figure 2.8: SEM Photographs of CVD Silicon Dioxide on Aluminum after 15000 C Anneal in Oxygen

  1. Periodically poled silicon

    NASA Astrophysics Data System (ADS)

    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.

  2. Structural alloy with a protective coating containing silicon or silicon-oxide

    DOEpatents

    Natesan, Ken

    1994-01-01

    An iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100.degree. C.

  3. Growth of silicon nanoclusters in thermal silicon dioxide under annealing in an atmosphere of nitrogen

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ivanova, E. V., E-mail: Ivanova@mail.ioffe.ru; Sitnikova, A. A.; Aleksandrov, O. V.

    2016-06-15

    It is found for the first time that silicon nanoclusters are formed in the surface layer of thermal silicon dioxide under high-temperature annealing (T = 1150°C) in dried nitrogen. Analysis of the cathodoluminescence spectra shows that an imperfect surface layer appears upon such annealing of silicon dioxide, with silicon nanoclusters formed in this layer upon prolonged annealing. Transmission electron microscopy demonstrated that the silicon clusters are 3–5.5 nm in size and lie at a depth of about 10 nm from the surface. Silicon from the thermal film of silicon dioxide serves as the material from which the silicon nanoclusters aremore » formed. This method of silicon-nanocluster formation is suggested for the first time.« less

  4. Diamond-silicon carbide composite

    DOEpatents

    Qian, Jiang; Zhao, Yusheng

    2006-06-13

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  5. Use of silicon in liquid sintered silicon nitrides and sialons

    DOEpatents

    Raj, R.; Baik, S.

    1984-12-11

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

  6. Use of silicon in liquid sintered silicon nitrides and sialons

    DOEpatents

    Raj, Rishi; Baik, Sunggi

    1984-12-11

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

  7. Crystallization of amorphous silicon thin films deposited by PECVD on nickel-metalized porous silicon.

    PubMed

    Ben Slama, Sonia; Hajji, Messaoud; Ezzaouia, Hatem

    2012-08-17

    Porous silicon layers were elaborated by electrochemical etching of heavily doped p-type silicon substrates. Metallization of porous silicon was carried out by immersion of substrates in diluted aqueous solution of nickel. Amorphous silicon thin films were deposited by plasma-enhanced chemical vapor deposition on metalized porous layers. Deposited amorphous thin films were crystallized under vacuum at 750°C. Obtained results from structural, optical, and electrical characterizations show that thermal annealing of amorphous silicon deposited on Ni-metalized porous silicon leads to an enhancement in the crystalline quality and physical properties of the silicon thin films. The improvement in the quality of the film is due to the crystallization of the amorphous film during annealing. This simple and easy method can be used to produce silicon thin films with high quality suitable for thin film solar cell applications.

  8. Crystallization of amorphous silicon thin films deposited by PECVD on nickel-metalized porous silicon

    PubMed Central

    2012-01-01

    Porous silicon layers were elaborated by electrochemical etching of heavily doped p-type silicon substrates. Metallization of porous silicon was carried out by immersion of substrates in diluted aqueous solution of nickel. Amorphous silicon thin films were deposited by plasma-enhanced chemical vapor deposition on metalized porous layers. Deposited amorphous thin films were crystallized under vacuum at 750°C. Obtained results from structural, optical, and electrical characterizations show that thermal annealing of amorphous silicon deposited on Ni-metalized porous silicon leads to an enhancement in the crystalline quality and physical properties of the silicon thin films. The improvement in the quality of the film is due to the crystallization of the amorphous film during annealing. This simple and easy method can be used to produce silicon thin films with high quality suitable for thin film solar cell applications. PMID:22901341

  9. Structural alloy with a protective coating containing silicon or silicon-oxide

    DOEpatents

    Natesan, K.

    1994-12-27

    An iron-based alloy is described containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100 C. 8 figures.

  10. Dislocation-free strained silicon-on-silicon by in-place bonding

    NASA Astrophysics Data System (ADS)

    Cohen, G. M.; Mooney, P. M.; Paruchuri, V. K.; Hovel, H. J.

    2005-06-01

    In-place bonding is a technique where silicon-on-insulator (SOI) slabs are bonded by hydrophobic attraction to the underlying silicon substrate when the buried oxide is undercut in dilute HF. The bonding between the exposed surfaces of the SOI slab and the substrate propagates simultaneously with the buried oxide etching. As a result, the slabs maintain their registration and are referred to as "bonded in-place". We report the fabrication of dislocation-free strained silicon slabs from pseudomorphic trilayer Si/SiGe/SOI by in-place bonding. Removal of the buried oxide allows the compressively strained SiGe film to relax elastically and induce tensile strain in the top and bottom silicon films. The slabs remain bonded to the substrate by van der Waals forces when the wafer is dried. Subsequent annealing forms a covalent bond such that when the upper Si and the SiGe layer are removed, the bonded silicon slab remains strained.

  11. Develop Silicone Encapsulation Systems for Terrestrial Silicon Solar Arrays

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The results of a study for Task 3 of the Low Cost Solar Array Project, directed toward the development of a cost effective encapsulation system for photovoltaic modules using silicon based materials, are reported. Results of the following are discussed: (1) weather-ometer stressing vs. weathering history of silicon and silicon modified materials; (2) humidity/temperature cycling exposure; (3) exposure at high humidity/high temperature; (4) outdoor exposure stress; (5) thermal cycling stress; and (6) UV screening agents. The plans for the next quarter are outlined.

  12. A silicon Brillouin laser

    NASA Astrophysics Data System (ADS)

    Otterstrom, Nils T.; Behunin, Ryan O.; Kittlaus, Eric A.; Wang, Zheng; Rakich, Peter T.

    2018-06-01

    Brillouin laser oscillators offer powerful and flexible dynamics as the basis for mode-locked lasers, microwave oscillators, and optical gyroscopes in a variety of optical systems. However, Brillouin interactions are markedly weak in conventional silicon photonic waveguides, stifling progress toward silicon-based Brillouin lasers. The recent advent of hybrid photonic-phononic waveguides has revealed Brillouin interactions to be one of the strongest and most tailorable nonlinearities in silicon. In this study, we have harnessed these engineered nonlinearities to demonstrate Brillouin lasing in silicon. Moreover, we show that this silicon-based Brillouin laser enters a regime of dynamics in which optical self-oscillation produces phonon linewidth narrowing. Our results provide a platform to develop a range of applications for monolithic integration within silicon photonic circuits.

  13. Periodically poled silicon

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

    We propose a new class of photonic devices based on periodic stress fields in silicon that enable second-order nonlinearity as well as quasi-phase matching. Periodically poled silicon (PePSi) 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 second-order nonlinear effects. As an example of the utility of the PePSi technology, we present simulations showing that midwave infrared radiation can be efficiently generated through difference frequency generation from near-infrared with a conversion efficiency of 50%.

  14. Structural alloy with a protective coating containing silicon or silicon-oxide

    DOEpatents

    Natesan, K.

    1992-01-01

    This invention is comprised of an iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100{degrees}C.

  15. Micromachined silicon electrostatic chuck

    DOEpatents

    Anderson, R.A.; Seager, C.H.

    1996-12-10

    An electrostatic chuck is faced with a patterned silicon plate, created by micromachining a silicon wafer, which is attached to a metallic base plate. Direct electrical contact between the chuck face (patterned silicon plate`s surface) and the silicon wafer it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands that protrude less than 5 micrometers from the otherwise flat surface of the chuck face. The islands may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face and wafer contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face, typically 0.5 to 5 percent. The pattern of the islands, together with at least one hole bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas. 6 figs.

  16. Micromachined silicon electrostatic chuck

    DOEpatents

    Anderson, Robert A.; Seager, Carleton H.

    1996-01-01

    An electrostatic chuck is faced with a patterned silicon plate 11, created y micromachining a silicon wafer, which is attached to a metallic base plate 13. Direct electrical contact between the chuck face 15 (patterned silicon plate's surface) and the silicon wafer 17 it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands 19 that protrude less than 5 micrometers from the otherwise flat surface of the chuck face 15. The islands 19 may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face 15 and wafer 17 contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands 19 are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face 15, typically 0.5 to 5 percent. The pattern of the islands 19, together with at least one hole 12 bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas.

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

    PubMed

    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

  18. Improved toughness of silicon carbide

    NASA Technical Reports Server (NTRS)

    Palm, J. A.

    1976-01-01

    Impact energy absorbing layers (EALs) comprised of partially densified silicon carbide were formed in situ on fully sinterable silicon carbide substrates. After final sintering, duplex silicon carbide structures resulted which were comprised of a fully sintered, high density silicon carbide substrate or core, overlayed with an EAL of partially sintered silicon carbide integrally bonded to its core member. Thermal cycling tests proved such structures to be moderately resistant to oxidation and highly resistant to thermal shock stresses. The strength of the developed structures in some cases exceeded but essentially it remained the same as the fully sintered silicon carbide without the EAL. Ballistic impact tests indicated that substantial improvements in the toughness of sintered silicon carbide were achieved by the use of the partially densified silicon carbide EALs.

  19. Fluidized bed silicon deposition from silane

    NASA Technical Reports Server (NTRS)

    Hsu, George C. (Inventor); Levin, Harry (Inventor); Hogle, Richard A. (Inventor); Praturi, Ananda (Inventor); Lutwack, Ralph (Inventor)

    1982-01-01

    A process and apparatus for thermally decomposing silicon containing gas for deposition on fluidized nucleating silicon seed particles is disclosed. Silicon seed particles are produced in a secondary fluidized reactor by thermal decomposition of a silicon containing gas. The thermally produced silicon seed particles are then introduced into a primary fluidized bed reactor to form a fluidized bed. Silicon containing gas is introduced into the primary reactor where it is thermally decomposed and deposited on the fluidized silicon seed particles. Silicon seed particles having the desired amount of thermally decomposed silicon product thereon are removed from the primary fluidized reactor as ultra pure silicon product. An apparatus for carrying out this process is also disclosed.

  20. Fluidized bed silicon deposition from silane

    NASA Technical Reports Server (NTRS)

    Hsu, George (Inventor); Levin, Harry (Inventor); Hogle, Richard A. (Inventor); Praturi, Ananda (Inventor); Lutwack, Ralph (Inventor)

    1984-01-01

    A process and apparatus for thermally decomposing silicon containing gas for deposition on fluidized nucleating silicon seed particles is disclosed. Silicon seed particles are produced in a secondary fluidized reactor by thermal decomposition of a silicon containing gas. The thermally produced silicon seed particles are then introduced into a primary fluidized bed reactor to form a fludized bed. Silicon containing gas is introduced into the primary reactor where it is thermally decomposed and deposited on the fluidized silicon seed particles. Silicon seed particles having the desired amount of thermally decomposed silicon product thereon are removed from the primary fluidized reactor as ultra pure silicon product. An apparatus for carrying out this process is also disclosed.

  1. Silicone-containing composition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mohamed, Mustafa

    A silicone-containing composition comprises the reaction product of a first component and an excess of an isocyanate component relative to the first component to form an isocyanated intermediary. The first component is selected from one of a polysiloxane and a silicone resin. The first component includes a carbon-bonded functional group selected from one of a hydroxyl group and an amine group. The isocyanate component is reactive with the carbon-bonded functional group of the first component. The isocyanated intermediary includes a plurality of isocyanate functional groups. The silicone-containing composition comprises the further reaction product of a second component, which is selectedmore » from the other of the polysiloxane and the silicone resin. The second component includes a plurality of carbon-bonded functional groups reactive with the isocyanate functional groups of the isocyanated intermediary for preparing the silicone-containing composition.« less

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

    NASA Technical Reports Server (NTRS)

    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.

  3. Silicon halide-alkali metal flames as a source of solar grade silicon

    NASA Technical Reports Server (NTRS)

    Olsen, D. B.; Miller, W. J.

    1979-01-01

    The feasibility of using alkali metal-silicon halide diffusion flames to produce solar-grade silicon in large quantities and at low cost is demonstrated. Prior work shows that these flames are stable and that relatively high purity silicon can be produced using Na + SiCl4 flames. Silicon of similar purity is obtained from Na + SiF4 flames although yields are lower and product separation and collection are less thermochemically favored. Continuous separation of silicon from the byproduct alkali salt was demonstrated in a heated graphite reactor. The process was scaled up to reduce heat losses and to produce larger samples of silicon. Reagent delivery systems, scaled by a factor of 25, were built and operated at a production rate of 0.5 kg Si/h. Very rapid reactor heating rates are observed with wall temperatures reaching greater than 2000 K. Heat release parameters were measured using a cooled stainless steel reactor tube. A new reactor was designed.

  4. Bond Sensitivity to Silicone Contamination

    NASA Technical Reports Server (NTRS)

    Caldwell, G. A.; Hudson, W. D.; Hudson, W. D.; Cash, Stephen F. (Technical Monitor)

    2003-01-01

    Currently during fabrication of the Space Shuttle booster rocket motors, the use of silicone and silicone-containing products is prohibited in most applications. Many shop aids and other materials containing silicone have the potential, if they make contact with a bond surface, to transfer some of the silicone to the substrates being bonded. Such transfer could result in a reduction of the bond strength or even failure of the subsequent bonds. This concern is driving the need to understand the effect of silicones and the concentration needed to affect a given bond-line strength. Additionally, as silicone detection methods used for materials acceptance improve what may have gone unnoticed earlier is now being detected. Thus, realistic silicone limits for process materials (below which bond performance is satisfactory) are needed rather than having an absolute no silicone permitted policy.

  5. Silicone-specific blood lymphocyte response in women with silicone breast implants.

    PubMed Central

    Ojo-Amaize, E A; Conte, V; Lin, H C; Brucker, R F; Agopian, M S; Peter, J B

    1994-01-01

    A blinded cross-sectional study was carried out with 99 women, 44 of whom had silicone breast implants. Group I consisted of 55 healthy volunteer women without breast implants; group II comprised 13 volunteer women with breast implants or explants who felt healthy; group III comprised 21 volunteer women with breast implants who had chronic fatigue, musculoskeletal symptoms, and skin disorders; and group IV comprised 10 women who had their prostheses explanted but still presented with clinical symptoms similar to those of the women in group III. Proliferative responses of peripheral blood mononuclear cells from all 99 women were measured by [3H]thymidine uptake after exposure to SiO2 silicon, or silicone gel. The levels of proliferative responses were expressed as stimulation indices, which were obtained by dividing the counts per minute of stimulated cells by the counts per minute of unstimulated cells. Abnormal responses to SiO2, silicon, or silicone gel were defined as a stimulation index of > 2.8, > 2.1, or > 2.4, respectively. Abnormal responses were observed in 0% of group I, 15% of group II, 29% of group III, and 30% of group IV (P < 0.0005 for group I versus groups II and IV). Thirty-one percent of symptomatic women with silicone gel breast implants had elevated serum silicon levels ( > 0.18 mg/liter); however, there was no significant correlation between abnormal cellular responses and silicon levels in blood serum, type of implant, time since first implantation, prosthesis explantation, number of implants, or report of implant leakage or rupture.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8556522

  6. Release and skin distribution of silicone-related compound(s) from a silicone gel sheet in vitro.

    PubMed

    Shigeki, S; Nobuoka, N; Murakami, T; Ikuta, Y

    1999-01-01

    The efficacy of topical silicone gel sheeting in prevention and/or reduction of keloids and hypertrophic scars is well recognized. In the present study, we reexamined the possible release of silicone-related compound(s) from a commercially available silicone gel sheet (Cica-Care, Smith and Nephew, Hull, England) in aqueous media in vitro. The silicone gel sheet was also applied on the excised skin surface to examine the possible distribution of silicone-related compounds into the skin in vitro. Silicone-related compounds were measured as silicon by an inductively coupled plasma-atomic emission spectrophotometer. When a piece of silicone gel sheet was placed in phosphate buffer solution (pH 3-9) at 37 degrees C for 7 days, the concentration of silicon in the medium increased with time, depending on the pH of the medium. This indicates that the released silicone-related compounds are water-soluble. When Cica-Care was applied on the surface of excised rat skin, human axilla skin and hypertrophic scars under hydrated conditions in vitro, silicon was detected in all skin samples. Greater distribution was observed in rat skin than in human axilla skin and hypertrophic scars. The release of silicone-related compounds from a silicone gel sheet (Cica-Care) and their distribution into the skin were demonstrated in vitro. Silicone-related compounds distributed into the skin may have pharmacological effects on the skin. Further investigation will be necessary to investigate in detail the action of silicone-related compounds on the proliferation of fibroblasts and excessive production of collagen.

  7. Stability and rheology of dispersions of silicon nitride and silicon carbide

    NASA Technical Reports Server (NTRS)

    Feke, Donald L.

    1987-01-01

    The relationship between the surface and colloid chemistry of commercial ultra-fine silicon carbide and silicon nitride powders was examined by a variety of standard characterization techniques and by methodologies especially developed for ceramic dispersions. These include electrokinetic measurement, surface titration, and surface spectroscopies. The effects of powder pretreatment and modification strategies, which can be utilized to augment control of processing characteristics, were monitored with these technologies. Both silicon carbide and nitride were found to exhibit silica-like surface chemistries, but silicon nitride powders possess an additional amine surface functionality. Colloidal characteristics of the various nitride powders in aqueous suspension is believed to be highly dependent on the relative amounts of the two types of surface groups, which in turn is determined by the powder synthesis route. The differences in the apparent colloidal characteristics for silicon nitride powders cannot be attributed to the specific absorption of ammonium ions. Development of a model for the prediction of double-layer characteristics of materials with a hybrid site interface facilitated understanding and prediction of the behavior of both surface charge and surface potential for these materials. The utility of the model in application to silicon nitride powders was demonstrated.

  8. Single-Event Effects in Silicon and Silicon Carbide Power Devices

    NASA Technical Reports Server (NTRS)

    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.

  9. Growth of silicon carbide crystals on a seed while pulling silicon crystals from a melt

    NASA Technical Reports Server (NTRS)

    Ciszek, T. F.; Schwuttke, G. H. (Inventor)

    1979-01-01

    A saturated solution of silicon and an element such as carbon having a segregation coefficient less than unity is formed by placing a solid piece of carbon in a body of molten silicon having a temperature differential decreasing toward the surface. A silicon carbide seed crystal is disposed on a holder beneath the surface of the molten silicon. As a rod or ribbon of silicon is slowly pulled from the melt, a supersaturated solution of carbon in silicon is formed in the vicinity of the seed crystal. Excess carbon is emitted from the solution in the form of silicon carbide which crystallizes on the seed crystal held in the cool region of the melt.

  10. Silicon carbide-free graphene growth on silicon for lithium-ion battery with high volumetric energy density

    PubMed Central

    Son, In Hyuk; Hwan Park, Jong; Kwon, Soonchul; Park, Seongyong; Rümmeli, Mark H.; Bachmatiuk, Alicja; Song, Hyun Jae; Ku, Junhwan; Choi, Jang Wook; Choi, Jae-man; Doo, Seok-Gwang; Chang, Hyuk

    2015-01-01

    Silicon is receiving discernable attention as an active material for next generation lithium-ion battery anodes because of its unparalleled gravimetric capacity. However, the large volume change of silicon over charge–discharge cycles weakens its competitiveness in the volumetric energy density and cycle life. Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation. The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l−1 at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries. This observation suggests that two-dimensional layered structure of graphene and its silicon carbide-free integration with silicon can serve as a prototype in advancing silicon anodes to commercially viable technology. PMID:26109057

  11. Porous Silicon Nanowires

    PubMed Central

    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

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

    DOEpatents

    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.

  13. Silicone Migration From Baked-on Silicone Layers. Particle Characterization in Placebo and Protein Solutions.

    PubMed

    Funke, Stefanie; Matilainen, Julia; Nalenz, Heiko; Bechtold-Peters, Karoline; Mahler, Hanns-Christian; Friess, Wolfgang

    2016-12-01

    A significant number of therapeutic proteins are marketed as pre-filled syringes or other drug/device combination products and have been safely used in these formats for years. Silicone oil, which is used as lubricant, can migrate into the drug product and may interact with therapeutic proteins. In this study, particles in the size range of 0.2-5 μm and ≥1 μm as determined by resonant mass measurement and micro-flow imaging/light obscuration, respectively, resulted from silicone sloughing off the container barrel after agitation. The degree of droplet formation correlated well with the applied baked-on silicone levels of 13 μg and 94 μg per cartridge. Silicone migration was comparable in placebo, 2 mg/mL and 33 mg/mL IgG1 formulations containing 0.04% (w/v) polysorbate 20. Headspace substantially increased the formation of silicone droplets during agitation. The highest particle concentrations reached, however, were still very low compared to numbers described for spray-on siliconized containers. When applying adequate baked-on silicone levels below 100 μg, bake-on siliconization efficiently limits silicone migration into the drug product without compromising device functionality. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  14. Through-silicon via-induced strain distribution in silicon interposer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vianne, B., E-mail: benjamin.vianne@st.com; STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles; Richard, M.-I.

    2015-04-06

    Strain in silicon induced by Through-Silicon Via (TSV) integration is of particular interest in the frame of the integration of active devices in silicon interposer. Nano-focused X-ray beam diffraction experiments were conducted using synchrotron radiation to investigate the thermally induced strain field in silicon around copper filled TSVs. Measurements were performed on thinned samples at room temperature and during in situ annealing at 400 °C. In order to correlate the 2D strain maps with finite elements analysis, an analytical model was developed, which takes into account beam absorption in the sample for a given diffraction geometry. The strain field along themore » [335] direction is found to be in the 10{sup −5} range at room temperature and around 10{sup −4} at 400 °C. Simulations support the expected plastification in some regions of the TSV during the annealing step.« less

  15. Silicon-on-ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project

    NASA Technical Reports Server (NTRS)

    Whitehead, A. B.; Zook, J. D.; Grung, B. L.; Heaps, J. D.; Schmit, F.; Schuldt, S. B.; Chapman, P. W.

    1981-01-01

    The technical feasibility of producing solar cell quality sheet silicon to meet the DOE 1986 cost goal of 70 cents/watt was investigated. The silicon on ceramic approach is to coat a low cost ceramic substrate with large grain polycrystalline silicon by unidirectional solidification of molten silicon. Results and accomplishments are summarized.

  16. Theoretical considerations for Reaction-Formed Silicon Carbide (RFSC) formation by molten silicon infiltration into slurry-derived preforms

    NASA Technical Reports Server (NTRS)

    Behrendt, D. R.; Singh, M.

    1993-01-01

    For reaction-formed silicon carbide (RFSC) ceramics produced by silicon melt infiltration of porous carbon preforms, equations are developed to relate the amount of residual silicon to the initial carbon density. Also, for a slurry derived preform containing both carbon and silicon powder, equations are derived which relate the amount of residual silicon in the RFSC to the relative density of the carbon in the preform and to the amount of silicon powder added to the slurry. For a porous carbon preform that does not have enough porosity to prevent choking-off of the silicon infiltration, these results show that complete silicon infiltration can occur by adding silicon powder to the slurry mixture used to produce these preforms.

  17. Silicon oxidation in fluoride solutions

    NASA Technical Reports Server (NTRS)

    Sancier, K. M.; Kapur, V.

    1980-01-01

    Silicon is produced in a NaF, Na2SiF6, and Na matrix when SiF4 is reduced by metallic sodium. Hydrogen is evolved during acid leaching to separate the silicon from the accompanying reaction products, NaF and Na2SiF6. The hydrogen evolution reaction was studied under conditions simulating leaching conditions by making suspensions of the dry silicon powder in aqueous fluoride solutions. The mechanism for the hydrogen evolution is discussed in terms of spontaneous oxidation of silicon resulting from the cooperative effects of (1) elemental sodium in the silicon that reacts with water to remove a protective silica layer, leaving clean reactive silicon, and (2) fluoride in solution that complexes with the oxidized silicon in solution and retards formation of a protective hydrous oxide gel.

  18. Process for producing silicon

    DOEpatents

    Olson, J.M.; Carleton, K.L.

    1982-06-10

    A process of producing silicon includes forming an alloy of copper and silicon and positioning the alloy in a dried, molten salt electrolyte to form a solid anode structure therein. An electrically conductive cathode is placed in the electrolyte for plating silicon thereon. The electrolyte is then purified to remove dissolved oxides. Finally, an electrical potential is applied between the anode and cathode in an amount sufficient to form substantially pure silicon on the cathode in the form of substantially dense, coherent deposits.

  19. Process for producing silicon

    DOEpatents

    Olson, Jerry M.; Carleton, Karen L.

    1984-01-01

    A process for producing silicon includes forming an alloy of copper and silicon and positioning the alloy in a dried, molten salt electrolyte to form a solid anode structure therein. An electrically conductive cathode is placed in the electrolyte for plating silicon thereon. The electrolyte is then purified to remove dissolved oxides. Finally, an electrical potential is applied between the anode and cathode in an amount sufficient to form substantially pure silicon on the cathode in the form of substantially dense, coherent deposits.

  20. Silicon-graphene photonic devices

    NASA Astrophysics Data System (ADS)

    Yin, Yanlong; Li, Jiang; Xu, Yang; Tsang, Hon Ki; Dai, Daoxin

    2018-06-01

    Silicon photonics has attracted much attention because of the advantages of CMOS (complementary-metal-oxide-semiconductor) compatibility, ultra-high integrated density, etc. Great progress has been achieved in the past decades. However, it is still not easy to realize active silicon photonic devices and circuits by utilizing the material system of pure silicon due to the limitation of the intrinsic properties of silicon. Graphene has been regarded as a promising material for optoelectronics due to its unique properties and thus provides a potential option for realizing active photonic integrated devices on silicon. In this paper, we present a review on recent progress of some silicon-graphene photonic devices for photodetection, all-optical modulation, as well as thermal-tuning. Project supported by the National Major Research and Development Program (No. 2016YFB0402502), the National Natural Science Foundation of China (Nos. 11374263, 61422510, 61431166001, 61474099, 61674127), and the National Key Research and Development Program (No. 2016YFA0200200).

  1. Silicon on ceramic process. Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Zook, J. D.; Heaps, J. D.; Maciolek, R. B.; Koepke, B. G.; Butter, C. D.; Schuldt, S. B.

    1977-01-01

    The technical and economic feasibility of producing solar-cell-quality sheet silicon was investigated. The sheets were made by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. Significant progress was made in all areas of the program.

  2. Electrodeposition of molten silicon

    DOEpatents

    De Mattei, Robert C.; Elwell, Dennis; Feigelson, Robert S.

    1981-01-01

    Silicon dioxide is dissolved in a molten electrolytic bath, preferably comprising barium oxide and barium fluoride. A direct current is passed between an anode and a cathode in the bath to reduce the dissolved silicon dioxide to non-alloyed silicon in molten form, which is removed from the bath.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  4. Process for purification of silicon

    NASA Technical Reports Server (NTRS)

    Rath, H. J.; Sirtl, E.; Pfeiffer, W.

    1981-01-01

    The purification of metallurgically pure silicon having a silicon content of more than 95% by weight is accomplished by leaching with an acidic solution which substantially does not attack silicon. A mechanical treatment leading to continuous particle size reduction of the granulated silicon to be purified is combined with the chemical purification step.

  5. Cleanroom Garment Silicone Contamination

    NASA Technical Reports Server (NTRS)

    Geer, Wayne; Lepage, Colette

    2006-01-01

    The slide presentation reviews actions taken at Goddard Space Flight Center (GSFC) to eliminate contamination by silicone in clean rooms. Background information includes facilities and hardware affected by silicon contamination, a discussion of the negative aspects of silicone contamination, clean room garments, and how the problem was identified at GSFC. Actions taken by the GSFC Contamination Engineering Group and lessons learned are detailed. Results include: awareness of the silicone issue in laundry, increase in infrastructure and support of the testing lab, establishment of protocols for garment verification, closer relationship established with laundry and converter, specifications for laundry services and garments were strengthened, all consumables are tested before use in clean rooms, and established procedures were used to identify and treat silicone found on face masks.

  6. Improved toughness of silicon carbide

    NASA Technical Reports Server (NTRS)

    Palm, J. A.

    1975-01-01

    Several techniques were employed to apply or otherwise form porous layers of various materials on the surface of hot-pressed silicon carbide ceramic. From mechanical properties measurements and studies, it was concluded that although porous layers could be applied to the silicon carbide ceramic, sufficient damage was done to the silicon carbide surface by the processing required so as to drastically reduce its mechanical strength. It was further concluded that there was little promise of success in forming an effective energy absorbing layer on the surface of already densified silicon carbide ceramic that would have the mechanical strength of the untreated or unsurfaced material. Using a process for the pressureless sintering of silicon carbide powders it was discovered that porous layers of silicon carbide could be formed on a dense, strong silicon carbide substrate in a single consolidation process.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Antoniadis, H.

    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 highmore » 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.« less

  8. [Study of purity tests for silicone resins].

    PubMed

    Sato, Kyoko; Otsuki, Noriko; Ohori, Akio; Chinda, Mitsuru; Furusho, Noriko; Osako, Tsutomu; Akiyama, Hiroshi; Kawamura, Yoko

    2012-01-01

    In the 8th edition of Japan's Specifications and Standards for Food Additives, the purity test for silicone resins requires the determination of the refractive index and kinetic viscosity of the extracted silicone oil, and allows for only a limited amount of silicon dioxide. In the purity test, carbon tetrachloride is used to separate the silicone oil and silicon dioxide. To exclude carbon tetrachloride, methods were developed for separating the silicone oil and silicon dioxide from silicone resin, which use hexane and 10% n-dodecylbenzenesulfonic acid in hexane. For silicone oil, the measured refractive index and kinetic viscosity of the silicone oil obtained from the hexane extract were shown to be equivalent to those of the intact silicone oil. In regard to silicon dioxide, it was confirmed that, following the separation with 10% n-dodecylbenzenesulfonic acid in hexane, the level of silicon dioxide in silicone resin can be accurately determined. Therefore, in this study, we developed a method for testing the purity of silicone resins without the use of carbon tetrachloride, which is a harmful reagent.

  9. Silicon web process development

    NASA Technical Reports Server (NTRS)

    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.

  10. Incorporation of dopant impurities into a silicon oxynitride matrix containing silicon nanocrystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ehrhardt, Fabien; Muller, Dominique; Slaoui, Abdelilah, E-mail: abdelilah.slaoui@unistra.fr

    2016-05-07

    Dopant impurities, such as gallium (Ga), indium (In), and phosphorus (P), were incorporated into silicon-rich silicon oxynitride (SRSON) thin films by the ion implantation technique. To form silicon nanoparticles, the implanted layers were thermally annealed at temperatures up to 1100 °C for 60 min. This thermal treatment generates a phase separation of the silicon nanoparticles from the SRSON matrix in the presence of the dopant atoms. We report on the position of the dopant species within the host matrix and relative to the silicon nanoparticles, as well as on the effect of the dopants on the crystalline structure and the size ofmore » the Si nanoparticles. The energy-filtered transmission electron microscopy technique is thoroughly used to identify the chemical species. The distribution of the dopant elements within the SRSON compound is determined using Rutherford backscattering spectroscopy. Energy dispersive X-ray mapping coupled with spectral imaging of silicon plasmons was performed to spatially localize at the nanoscale the dopant impurities and the silicon nanoparticles in the SRSON films. Three different behaviors were observed according to the implanted dopant type (Ga, In, or P). The In-doped SRSON layers clearly showed separated nanoparticles based on indium, InOx, or silicon. In contrast, in the P-doped SRSON layers, Si and P are completely miscible. A high concentration of P atoms was found within the Si nanoparticles. Lastly, in Ga-doped SRSON the Ga atoms formed large nanoparticles close to the SRSON surface, while the Si nanoparticles were localized in the bulk of the SRSON layer. In this work, we shed light on the mechanisms responsible for these three different behaviors.« less

  11. Method for one-to-one polishing of silicon nitride and silicon oxide

    NASA Technical Reports Server (NTRS)

    Babu, Suryadevara V. (Inventor); Natarajan, Anita (Inventor)

    2009-01-01

    The present invention provides a method of removing silicon nitride at about the same removal rate as silicon dioxide by CMP. The method utilizes a polishing slurry that includes colloidal silica abrasive particles dispersed in water and additives that modulate the silicon dioxide and silicon nitride removal rates such that they are about the same. In one embodiment of the invention, the additive is lysine or lysine mono hydrochloride in combination with picolinic acid, which is effective at a pH of about 8. In another embodiment of the invention, the additive is arginine in combination with picolinic acid, which is effective at a pH of about 10.

  12. Selective formation of porous silicon

    NASA Technical Reports Server (NTRS)

    Fathauer, Jones (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:H20. 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.

  13. Selective formation of porous silicon

    NASA Technical Reports Server (NTRS)

    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.

  14. Workshop summary: New silicon cells

    NASA Technical Reports Server (NTRS)

    Meulenberg, A.; Iles, P. A.

    1993-01-01

    The workshop on new silicon cells held during SPRAT12 is summarized. A smaller than average group attended this workshop reflecting the reduction in research dollars available to this portion of the photovoltaics community. Despite the maturity of the silicon technology, a core of the group maintained an excitement about new developments and potential opportunities. The group addressed both the implications and the applications of recent developments. Topics discussed include: light trapping and ultrathin silicon cells; different uses for silicon cells; new silicon cell developments; and radiation tolerant high efficiency cells.

  15. EPITAXIAL GROWTH OF SILICON

    DTIC Science & Technology

    Epitaxial growth of silicon on a silicon substrate by hydrogen reduction of SiCl4 was investigated. The chemical and physical processes involved in...silicon layers were produced at temperatures between 1100 and 1300 C. The effects of the concentration of SiCl4 in H2, the flow rate of the gas, the

  16. A novel preparation method for silicone oil nanoemulsions and its application for coating hair with silicone

    PubMed Central

    Hu, Zhenhua; Liao, Meiling; Chen, Yinghui; Cai, Yunpeng; Meng, Lele; Liu, Yajun; Lv, Nan; Liu, Zhenguo; Yuan, Weien

    2012-01-01

    Background Silicone oil, as a major component in conditioner, is beneficial in the moisture preservation and lubrication of hair. However, it is difficult for silicone oil to directly absorb on the hair surface because of its hydrophobicity. Stable nanoemulsions containing silicone oil may present as a potential solution to this problem. Methods Silicone oil nanoemulsions were prepared using the oil-in-water method with nonionic surfactants. Emulsion particle size and distribution were characterized by scanning electron microscopy. The kinetic stability of this nanoemulsion system was investigated under accelerated stability tests and long-term storage. The effect of silicone oil deposition on hair was examined by analyzing the element of hair after treatment of silicone oil nanoemulsions. Results Nonionic surfactants such as Span 80 and Tween 80 are suitable emulsifiers to prepare oil-in-water nanoemulsions that are both thermodynamically stable and can enhance the absorption of silicone oil on hair surface. Conclusion The silicone oil-in-water nanoemulsions containing nonionic surfactants present as a promising solution to improve the silicone oil deposition on the hair surface for hair care applications. PMID:23166436

  17. Aquaporins Mediate Silicon Transport in Humans.

    PubMed

    Garneau, Alexandre P; Carpentier, Gabriel A; Marcoux, Andrée-Anne; Frenette-Cotton, Rachelle; Simard, Charles F; Rémus-Borel, Wilfried; Caron, Luc; Jacob-Wagner, Mariève; Noël, Micheline; Powell, Jonathan J; Bélanger, Richard; Côté, François; Isenring, Paul

    2015-01-01

    In animals, silicon is an abundant and differentially distributed trace element that is believed to play important biological functions. One would thus expect silicon concentrations in body fluids to be regulated by silicon transporters at the surface of many cell types. Curiously, however, and even though they exist in plants and algae, no such transporters have been identified to date in vertebrates. Here, we show for the first time that the human aquaglyceroporins, i.e., AQP3, AQP7, AQP9 and AQP10 can act as silicon transporters in both Xenopus laevis oocytes and HEK-293 cells. In particular, heterologously expressed AQP7, AQP9 and AQP10 are all able to induce robust, saturable, phloretin-sensitive silicon transport activity in the range that was observed for low silicon rice 1 (lsi1), a silicon transporter in plant. Furthermore, we show that the aquaglyceroporins appear as relevant silicon permeation pathways in both mice and humans based on 1) the kinetics of substrate transport, 2) their presence in tissues where silicon is presumed to play key roles and 3) their transcriptional responses to changes in dietary silicon. Taken together, our data provide new evidence that silicon is a potentially important biological element in animals and that its body distribution is regulated. They should open up original areas of investigations aimed at deciphering the true physiological role of silicon in vertebrates.

  18. Low loss poly-silicon for high performance capacitive silicon modulators.

    PubMed

    Douix, Maurin; Baudot, Charles; Marris-Morini, Delphine; Valéry, Alexia; Fowler, Daivid; Acosta-Alba, Pablo; Kerdilès, Sébastien; Euvrard, Catherine; Blanc, Romuald; Beneyton, Rémi; Souhaité, Aurélie; Crémer, Sébastien; Vulliet, Nathalie; Vivien, Laurent; Boeuf, Frédéric

    2018-03-05

    Optical properties of poly-silicon material are investigated to be integrated in new silicon photonics devices, such as capacitive modulators. Test structure fabrication is done on 300 mm wafer using LPCVD deposition: 300 nm thick amorphous silicon layers are deposited on thermal oxide, followed by solid phase crystallization anneal. Rib waveguides are fabricated and optical propagation losses measured at 1.31 µm. Physical analysis (TEM ASTAR, AFM and SIMS) are used to assess the origin of losses. Optimal deposition and annealing conditions have been defined, resulting in 400 nm-wide rib waveguides with only 9.2-10 dB/cm losses.

  19. Silicon isotope fractionation in bamboo and its significance to the biogeochemical cycle of silicon

    NASA Astrophysics Data System (ADS)

    Ding, T. P.; Zhou, J. X.; Wan, D. F.; Chen, Z. Y.; Wang, C. Y.; Zhang, F.

    2008-03-01

    A systematic investigation on silica contents and silicon isotope compositions of bamboos was undertaken. Seven bamboo plants and related soils were collected from seven locations in China. The roots, stem, branch and leaves for each plant were sampled and their silica contents and silicon isotope compositions were determined. The silica contents and silicon isotope compositions of bulk and water-soluble fraction of soils were also measured. The silica contents of studied bamboo organs vary from 0.30% to 9.95%. Within bamboo plant the silica contents show an increasing trend from stem, through branch, to leaves. In bamboo roots the silica is exclusively in the endodermis cells, but in stem, branch and leaves, the silica is accumulated mainly in epidermal cells. The silicon isotope compositions of bamboos exhibit significant variation, from -2.3‰ to 1.8‰, and large and systematic silicon isotope fractionation was observed within each bamboo. The δ 30Si values decrease from roots to stem, but then increase from stem, through branch, to leaves. The ranges of δ 30Si values within each bamboo vary from 1.0‰ to 3.3‰. Considering the total range of silicon isotope composition in terrestrial samples is only 7‰, the observed silicon isotope variation in single bamboo is significant and remarkable. This kind of silicon isotope variation might be caused by isotope fractionation in a Rayleigh process when SiO 2 precipitated in stem, branches and leaves gradually from plant fluid. In this process the Si isotope fractionation factor between dissolved Si and precipitated Si in bamboo ( αpre-sol) is estimated to be 0.9981. However, other factors should be considered to explain the decrease of δ 30Si value from roots to stem, including larger ratio of dissolved H 4SiO 4 to precipitated SiO 2 in roots than in stem. There is a positive correlation between the δ 30Si values of water-soluble fractions in soils and those of bulk bamboos, indicating that the dissolved

  20. Review Application of Nanostructured Black Silicon

    NASA Astrophysics Data System (ADS)

    Lv, Jian; Zhang, Ting; Zhang, Peng; Zhao, Yingchun; Li, Shibin

    2018-04-01

    As a widely used semiconductor material, silicon has been extensively used in many areas, such as photodiode, photodetector, and photovoltaic devices. However, the high surface reflectance and large bandgap of traditional bulk silicon restrict the full use of the spectrum. To solve this problem, many methods have been developed. Among them, the surface nanostructured silicon, namely black silicon, is the most efficient and widely used. Due to its high absorption in the wide range from UV-visible to infrared, black silicon is very attractive for using as sensitive layer of photodiodes, photodetector, solar cells, field emission, luminescence, and other photoelectric devices. Intensive study has been performed to understand the enhanced absorption of black silicon as well as the response extended to infrared spectrum range. In this paper, the application of black silicon is systematically reviewed. The limitations and challenges of black silicon material are also discussed. This article will provide a meaningful introduction to black silicon and its unique properties.

  1. Hall mobility in multicrystalline silicon

    NASA Astrophysics Data System (ADS)

    Schindler, F.; Geilker, J.; Kwapil, W.; Warta, W.; Schubert, M. C.

    2011-08-01

    Knowledge of the carrier mobility in silicon is of utmost importance for photovoltaic applications, as it directly influences the diffusion length and thereby the cell efficiency. Moreover, its value is needed for a correct quantitative evaluation of a variety of lifetime measurements. However, models that describe the carrier mobility in silicon are based on theoretical calculations or fits to experimental data in monocrystalline silicon. Multicrystalline (mc) silicon features crystal defects such as dislocations and grain boundaries, with the latter possibly leading to potential barriers through the trapping of charge carriers and thereby influencing the mobility, as shown, for example, by Maruska et al. [Appl. Phys. Lett. 36, 381 (1980)]. To quantify the mobilities in multicrystalline silicon, we performed Hall measurements in p-type mc-Si samples of various resistivities and different crystal structures and compared the data to majority carrier Hall mobilities in p-type monocrystalline floatzone (FZ) silicon. For lack of a model that provides reliable values of the Hall mobility in silicon, an empirical fit similar to existing models for conductivity mobilities is proposed based on Hall measurements of monocrystalline p-type FZ silicon. By comparing the measured Hall mobilities obtained from mc silicon with the corresponding Hall mobilities in monocrystalline silicon of the same resistivity, we found that the mobility reduction due to the presence of crystal defects in mc-Si ranges between 0% and 5% only. Mobility decreases of up to 30% as reported by Peter et al. [Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain, 1-5 September 2008], or even of a factor of 2 to 3 as detected by Palais et al. [Mater. Sci. Eng. B 102, 184 (2003)], in multicrystalline silicon were not observed.

  2. Fibers based on polyethylene with silicon and silicon carbide nanoparticles

    NASA Astrophysics Data System (ADS)

    Olkhov, A. A.; Krutikova, A. A.; Kovaleva, A. N.; Rychagov, O. V.; Ischenko, A. A.

    2017-12-01

    In the paper, fibrous materials based on polyethylene with nanosized silicon and silicon carbide obtained by the plasma chemical method have been obtained. The concentration of nanosilicon nanoparticles was 0.1-1.5%. Fibers absorb UV radiation in the range 200-400 nm. The size of silicon nanoparticles and dispersion in fibers are estimated by X-ray diffraction. It is shown that silicon nanoparticles exert no effect on the formation of the internal structure of the PE matrix. The degree of crystallinity, melting and crystallization temperatures remain constant. The surface properties of films are investigated by triboelectric methods and by determining the wetting angle. The surface properties of composite films do not differ from the properties of PE films with the concentration of nanoparticles from 0.1 to 1.0%. At a 1.5% content of n-SiC, the microrelief of the surface changes, and the friction coefficient of the films increases. The resulting films are recommended for application as a UV protective coating.

  3. Process for making silicon

    NASA Technical Reports Server (NTRS)

    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.

  4. Silicone Gel-Filled Breast Implants

    MedlinePlus

    ... and Medical Procedures Implants and Prosthetics Breast Implants Silicone Gel-Filled Breast Implants Share Tweet Linkedin Pin ... sharing options Linkedin Pin it Email Print Description: Silicone gel-filled breast implants have a silicone outer ...

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Aquaporins Mediate Silicon Transport in Humans

    PubMed Central

    Garneau, Alexandre P.; Carpentier, Gabriel A.; Marcoux, Andrée-Anne; Frenette-Cotton, Rachelle; Simard, Charles F.; Rémus-Borel, Wilfried; Caron, Luc; Jacob-Wagner, Mariève; Noël, Micheline; Powell, Jonathan J.; Bélanger, Richard; Côté, François; Isenring, Paul

    2015-01-01

    In animals, silicon is an abundant and differentially distributed trace element that is believed to play important biological functions. One would thus expect silicon concentrations in body fluids to be regulated by silicon transporters at the surface of many cell types. Curiously, however, and even though they exist in plants and algae, no such transporters have been identified to date in vertebrates. Here, we show for the first time that the human aquaglyceroporins, i.e., AQP3, AQP7, AQP9 and AQP10 can act as silicon transporters in both Xenopus laevis oocytes and HEK-293 cells. In particular, heterologously expressed AQP7, AQP9 and AQP10 are all able to induce robust, saturable, phloretin-sensitive silicon transport activity in the range that was observed for low silicon rice 1 (lsi1), a silicon transporter in plant. Furthermore, we show that the aquaglyceroporins appear as relevant silicon permeation pathways in both mice and humans based on 1) the kinetics of substrate transport, 2) their presence in tissues where silicon is presumed to play key roles and 3) their transcriptional responses to changes in dietary silicon. Taken together, our data provide new evidence that silicon is a potentially important biological element in animals and that its body distribution is regulated. They should open up original areas of investigations aimed at deciphering the true physiological role of silicon in vertebrates. PMID:26313002

  7. Surface reaction of silicon chlorides during atomic layer deposition of silicon nitride

    NASA Astrophysics Data System (ADS)

    Yusup, Luchana L.; Park, Jae-Min; Mayangsari, Tirta R.; Kwon, Young-Kyun; Lee, Won-Jun

    2018-02-01

    The reaction of precursor with surface active site is the critical step in atomic layer deposition (ALD) process. We performed the density functional theory calculation with DFT-D correction to study the surface reaction of different silicon chloride precursors during the first half cycle of ALD process. SiCl4, SiH2Cl2, Si2Cl6 and Si3Cl8 were considered as the silicon precursors, and an NH/SiNH2*-terminated silicon nitride surface was constructed to model the thermal ALD processes using NH3 as well as the PEALD processes using NH3 plasma. The total energies of the system were calculated for the geometry-optimized structures of physisorption, chemisorption, and transition state. The order of silicon precursors in energy barrier, from lowest to highest, is Si3Cl8 (0.92 eV), Si2Cl6 (3.22 eV), SiH2Cl2 (3.93 eV) and SiCl4 (4.49 eV). Silicon precursor with lower energy barrier in DFT calculation showed lower saturation dose in literature for both thermal and plasma-enhanced ALD of silicon nitride. Therefore, DFT calculation is a promising tool in predicting the reactivity of precursor during ALD process.

  8. Consequences of Atomic Oxygen Interaction With Silicone and Silicone Contamination on Surfaces in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon K.; Haytas, Christy A.

    1999-01-01

    The exposure of silicones to atomic oxygen in low Earth orbit causes oxidation of the surface, resulting in conversion of silicone to silica. This chemical conversion increases the elastic modulus of the surface and initiates the development of a tensile strain. Ultimately, with sufficient exposure, tensile strain leads to cracking of the surface enabling the underlying unexposed silicone to be converted to silica resulting in additional depth and extent of cracking. The use of silicone coatings for the protection of materials from atomic oxygen attack is limited because of the eventual exposure of underlying unprotected polymeric material due to deep tensile stress cracking of the oxidized silicone. The use of moderate to high volatility silicones in low Earth orbit has resulted in a silicone contamination arrival at surfaces which are simultaneously being bombarded with atomic oxygen, thus leading to conversion of the silicone contaminant to silica. As a result of these processes, a gradual accumulation of contamination occurs leading to deposits which at times have been up to several microns thick (as in the case of a Mir solar array after 10 years in space). The contamination species typically consist of silicon, oxygen and carbon. which in the synergistic environment of atomic oxygen and UV radiation leads to increased solar absorptance and reduced solar transmittance. A comparison of the results of atomic oxygen interaction with silicones and silicone contamination will be presented based on the LDEF, EOIM-111, Offeq-3 spacecraft and Mir solar array in-space results. The design of a contamination pin-hole camera space experiment which uses atomic oxygen to produce an image of the sources of silicone contamination will also be presented.

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

    NASA Astrophysics Data System (ADS)

    Hussain, Muhammad M.; Rojas, Jhonathan P.; Torres Sevilla, Galo A.

    2013-05-01

    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%).

  10. An FPGA-Based Silicon Neuronal Network with Selectable Excitability Silicon Neurons

    PubMed Central

    Li, Jing; Katori, Yuichi; Kohno, Takashi

    2012-01-01

    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 us to tune the excitability of silicon neurons 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. PMID:23269911

  11. Nanostructured silicon for thermoelectric

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  13. 1366 Project Silicon: Reclaiming US Silicon PV Leadership

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lorenz, Adam

    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 ofmore » 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. Sun

  14. Investigation of silicon surface passivation by silicon nitride film deposition

    NASA Technical Reports Server (NTRS)

    Olsen, L. C.

    1984-01-01

    The use of Sin sub x grown by plasma enhanced chemical vapor deposition (PECVO) for passivating silicon surfaces was studied. The application of PECVO SiN sub x films for passivations of silicon N+/P or P+/N solar cells is of particular interest. This program has involved the following areas of investigation: (1) Establishment of PECVO system and development of procedures for growth of SiN sub x; (2) Optical characterization of SiN sub x films; (3) Characterization of the SiN sub x/Si interface; (4) Surface recombination velocity deduced from photoresponse; (5) Current-Voltage analyses of silicon N+/P cells; and (6) Gated diode device studies.

  15. Comparison of the surface charge behavior of commercial silicon nitride and silicon carbide powders

    NASA Technical Reports Server (NTRS)

    Whitman, Pamela K.; Feke, Donald L.

    1988-01-01

    The adsorption and desorption of protons from aqueous solution onto the surfaces of a variety of commercial silicon carbide and silicon nitride powders has been examined using a surface titration methodology. This method provides information on some colloidal characteristics, such as the point of zero charge (pzc) and the variation of proton adsorption with dispersion pH, useful for the prediction of optimal ceramic-processing conditions. Qualitatively, the magnitude of the proton adsorption from solution reveals small differences among all of the materials studied. However, the results show that the pzc for the various silicon nitride powders is affected by the powder synthesis route. Complementary investigations have shown that milling can also act to shift the pzc exhibited by silicon nitride powder. Also, studies of the role of the electrolyte in the development of surface charge have indicated no evidence of specific adsorption of ammonium ion on either silicon nitride or silicon carbide powders.

  16. Endoscopic dacryocystorhinostomy without silicone stent.

    PubMed

    Yeon, Je Yeob; Shim, Woo Sub

    2012-06-01

    In nasolacrimal duct (NLD) obstruction patients that undergo endoscopic dacryocystorhinostomy (DCR), creation of a patent rhinostomy with adequate epithelialization can be accomplished without a stent. However, in common canalicular obstruction patients, a silicone stent seems to have a beneficial role and to bear more favorable results. The aim of this study was to evaluate the surgical outcome of endoscopic DCR without the use of a silicone stent. In all, 36 patients (41 eyes) who underwent endoscopic DCR were enrolled in this study. The patients were classified into a DCR with silicone stent group and a DCR without silicone stent group. Then each of the groups was subdivided into common canalicular obstruction group and NLD obstruction group. Surgical outcomes were evaluated by postoperative symptom improvement and patency of the rhinostomy under nasal endoscopic exam. The epiphora was improved in 84.2% of the silicone stent group and 81.8% of the non-silicone stent group. Categorized by the level of obstruction, in common canalicular obstruction, the success rate was 84.5% (11/13) in the silicone stent group and 57.1% (4/7) in the no stent group. In NLD obstruction, the success rate was 83.0% (5/6) in the silicone stent group and 93.3% (14/15) in the no stent group.

  17. Area Reports. Advanced materials and devices research area. Silicon materials research task, and advanced silicon sheet task

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The objectives of the Silicon Materials Task and the Advanced Silicon Sheet Task are to identify the critical technical barriers to low-cost silicon purification and sheet growth that must be overcome to produce a PV cell substrate material at a price consistent with Flat-plate Solar Array (FSA) Project objectives and to overcome these barriers by performing and supporting appropriate R&D. Progress reports are given on silicon refinement using silane, a chemical vapor transport process for purifying metallurgical grade silicon, silicon particle growth research, and modeling of silane pyrolysis in fluidized-bed reactors.

  18. Porous silicon carbide (SIC) semiconductor device

    NASA Technical Reports Server (NTRS)

    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.

  19. Narrow band gap amorphous silicon semiconductors

    DOEpatents

    Madan, A.; Mahan, A.H.

    1985-01-10

    Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.

  20. Roadmap on silicon photonics

    NASA Astrophysics Data System (ADS)

    Thomson, David; Zilkie, Aaron; Bowers, John E.; Komljenovic, Tin; Reed, Graham T.; Vivien, Laurent; Marris-Morini, Delphine; Cassan, Eric; Virot, Léopold; Fédéli, Jean-Marc; Hartmann, Jean-Michel; Schmid, Jens H.; Xu, Dan-Xia; Boeuf, Frédéric; O'Brien, Peter; Mashanovich, Goran Z.; Nedeljkovic, M.

    2016-07-01

    Silicon photonics research can be dated back to the 1980s. However, the previous decade has witnessed an explosive growth in the field. Silicon photonics is a disruptive technology that is poised to revolutionize a number of application areas, for example, data centers, high-performance computing and sensing. The key driving force behind silicon photonics is the ability to use CMOS-like fabrication resulting in high-volume production at low cost. This is a key enabling factor for bringing photonics to a range of technology areas where the costs of implementation using traditional photonic elements such as those used for the telecommunications industry would be prohibitive. Silicon does however have a number of shortcomings as a photonic material. In its basic form it is not an ideal material in which to produce light sources, optical modulators or photodetectors for example. A wealth of research effort from both academia and industry in recent years has fueled the demonstration of multiple solutions to these and other problems, and as time progresses new approaches are increasingly being conceived. It is clear that silicon photonics has a bright future. However, with a growing number of approaches available, what will the silicon photonic integrated circuit of the future look like? This roadmap on silicon photonics delves into the different technology and application areas of the field giving an insight into the state-of-the-art as well as current and future challenges faced by researchers worldwide. Contributions authored by experts from both industry and academia provide an overview and outlook for the silicon waveguide platform, optical sources, optical modulators, photodetectors, integration approaches, packaging, applications of silicon photonics and approaches required to satisfy applications at mid-infrared wavelengths. Advances in science and technology required to meet challenges faced by the field in each of these areas are also addressed together with

  1. Silicon isotope fractionation in rice and cucumber plants over a life cycle: Laboratory studies at different external silicon concentrations

    NASA Astrophysics Data System (ADS)

    Sun, Yan; Wu, Lianghuan; Li, Xiaoyan; Sun, Li; Gao, Jianfei; Ding, Tiping

    2016-11-01

    Understanding the variations of silicon isotopes in terrestrial higher plants can be helpful toward elucidating the global biogeochemical silicon cycle. We studied silicon isotope fractionation in rice and cucumber plants over their entire life cycles. These two different silicon-absorbing plants were grown hydroponically at different external silicon concentrations. The ranges of δ30Si values in rice were -1.89‰ to 1.69‰, -1.81‰ to 1.96‰, and -2.08‰ to 2.02‰ at 0.17 mM, 1.70 mM, and 8.50 mM silicon concentrations, respectively. The ranges of δ30Si values in cucumber were -1.38‰ to 1.21‰, -1.33‰ to 1.26‰, and -1.62‰ to 1.40‰ at 0.085 mM, 0.17 mM, and 1.70 mM external silicon concentrations, respectively. A general increasing trend in δ30Si values from lower to upper plant parts reflected the preferential incorporation of lighter silicon isotopes from transpired water to biogenic opal. Furthermore, the active uptake mechanism regulated by several transporters might have also played an important role in the preferential transport of heavy silicon isotopes into aboveground plant parts. This suggested that silicon isotope fractionation in both rice and cucumber was a Rayleigh-like process. The data on δ30Si values for the whole plants and nutrient solutions indicated that biologically mediated silicon isotope fractionation occurred during silicon uptake by roots. At lower external silicon concentrations, heavy silicon isotopes entered plants more readily than light silicon isotopes. Conversely, at higher external silicon concentrations, light silicon isotopes entered plants more readily than heavy silicon isotopes.

  2. Method of forming buried oxide layers in silicon

    DOEpatents

    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.

  3. Engineering functionalized multi-phased silicon/silicon oxide nano-biomaterials to passivate the aggressive proliferation of cancer

    PubMed Central

    Premnath, P.; Tan, B.; Venkatakrishnan, K.

    2015-01-01

    Currently, the use of nano silicon in cancer therapy is limited as drug delivery vehicles and markers in imaging, not as manipulative/controlling agents. This is due to limited properties that native states of nano silicon and silicon oxides offers. We introduce nano-functionalized multi-phased silicon/silicon oxide biomaterials synthesized via ultrashort pulsed laser synthesis, with tunable properties that possess inherent cancer controlling properties that can passivate the progression of cancer. This nanostructured biomaterial is composed of individual functionalized nanoparticles made of a homogenous hybrid of multiple phases of silicon and silicon oxide in increasing concentration outwards from the core. The chemical properties of the proposed nanostructure such as number of phases, composition of phases and crystal orientation of each functionalized nanoparticle in the three dimensional nanostructure is defined based on precisely tuned ultrashort pulsed laser-material interaction mechanisms. The amorphous rich phased biomaterial shows a 30 fold (95%) reduction in number of cancer cells compared to bulk silicon in 48 hours. Further, the size of the cancer cells reduces by 76% from 24 to 48 hours. This method exposes untapped properties of combination of multiple phases of silicon oxides and its applications in cancer therapy. PMID:26190009

  4. Use of free silicon in liquid phase sintering of silicon nitrides and sialons

    DOEpatents

    Raj, R.; Baik, S.

    1985-11-12

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

  5. Use of free silicon in liquid phase sintering of silicon nitrides and sialons

    DOEpatents

    Raj, Rishi; Baik, Sunggi

    1985-11-12

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

  6. Removal of inclusions from silicon

    NASA Astrophysics Data System (ADS)

    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.

  7. Vertically aligned silicon microwire arrays of various lengths by repeated selective vapor-liquid-solid growth of n-type silicon/n-type silicon

    NASA Astrophysics Data System (ADS)

    Ikedo, Akihito; Kawashima, Takahiro; Kawano, Takeshi; Ishida, Makoto

    2009-07-01

    Repeated vapor-liquid-solid (VLS) growth with Au and PH3-Si2H6 mixture gas as the growth catalyst and silicon source, respectively, was used to construct n-type silicon/n-type silicon wire arrays of various lengths. Silicon wires of various lengths within an array could be grown by employing second growth over the first VLS grown wire. Additionally, the junction at the interface between the first and the second wires were examined. Current-voltage measurements of the wires exhibited linear behavior with a resistance of 850 Ω, confirming nonelectrical barriers at the junction, while bending tests indicated that the mechanical properties of the wire did not change.

  8. Silicon-on ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project

    NASA Technical Reports Server (NTRS)

    Grung, B. L.; Heaps, J. D.; Schmit, F. M.; Schuldt, S. B.; Zook, J. D.

    1981-01-01

    The technical feasibility of producing solar-cell-quality sheet silicon to meet the Department of Energy (DOE) 1986 overall price goal of $0.70/watt was investigated. With the silicon-on-ceramic (SOC) approach, a low-cost ceramic substrate is coated with large-grain polycrystalline silicon by unidirectional solidification of molten silicon. This effort was divided into several areas of investigation in order to most efficiently meet the goals of the program. These areas include: (1) dip-coating; (2) continuous coating designated SCIM-coating, and acronym for Silicon Coating by an Inverted Meniscus (SCIM); (3) material characterization; (4) cell fabrication and evaluation; and (5) theoretical analysis. Both coating approaches were successful in producing thin layers of large grain, solar-cell-quality silicon. The dip-coating approach was initially investigated and considerable effort was given to this technique. The SCIM technique was adopted because of its scale-up potential and its capability to produce more conventiently large areas of SOC.

  9. Compensated amorphous silicon solar cell

    DOEpatents

    Devaud, Genevieve

    1983-01-01

    An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon over said substrate and having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the electrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF.sub.3 doped intrinsic layer.

  10. Silicon microfabricated beam expander

    NASA Astrophysics Data System (ADS)

    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.

  11. Silicon production process evaluations

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Engineering design of the third distillation column in the process was accomplished. The initial design is based on a 94.35% recovery of dichlorosilane in the distillate and a 99.9% recovery of trichlorosilane in the bottoms. The specified separation is achieved at a reflux ratio of 15 with 20 trays (equilibrium stages). Additional specifications and results are reported including equipment size, temperatures and pressure. Specific raw material requirements necessary to produce the silicon in the process are presented. The primary raw materials include metallurgical grade silicon, silicon tetrachloride, hydrogen, copper (catalyst) and lime (waste treatment). Hydrogen chloride is produced as by product in the silicon deposition. Cost analysis of the process was initiated during this reporting period.

  12. A general classification of silicon utilizing organisms

    NASA Astrophysics Data System (ADS)

    Das, P.; Das, S.

    2010-12-01

    Silicon utilizing organisms may be defined as organisms with high silicon content (≥ 1% dry weight) and they can metabolize silicon with or without demonstrable silicon transporter genes (SIT) in them(Das,2010). Silicon is the second most abundant element in the lithosphere (27.70%) and it is as important as phosphorus and magnesium (0.03%) in the biota. Hydrated silica represents the second most abundant biogenic mineral after carbonate minerals. Silicon is accumulated and metabolized by some prokaryotes, and Si compounds can stimulate the growth of a range of fungi. It is well known that Si is essential for diatoms. In mammals, Si is considered an essential trace element, required in bone, cartilage and connective tissue formation, enzymatic activities and other metabolic processes. Silicon was suggested to act as a phosphoprotein effector in bone. In mammals, Si is also reported to positively influence the immune system and to be required for lymphocyte proliferation. The aqueous chemistry of Si is dominated by silicic acid at biological pH ranges. Monosilicic acid can form stable complexes with organic hydroxy-containing molecules . Biosilica also has been identified associated with various biomolecules including proteins and carbohydrates. There are main seven groups of silicon utilizing organisms belonging to Gram positive bacteria, algae, protozoa, sponges, fungi, lichens, and monocotyledon plants. In each group again all the members are not silicon utilizing organisms, thus selective members in each group are further classified depending their degree of silicon utilization. Important silicon utilizing bacteria are Mycobacteria, Nocardia, Streptomyces, Staphylococcus, Bacillus, Lactobacillus spp. etc., Important silicon utilizing algae are Centrobacillariophyceae, Pennatibacillariophyceae and Chrysophyceae. Many protozoa belonging to Heterokonta, Choanoflagellida, Actinopoda are well known silicon utilizing microorganisms. Hexactinellida ( glass sponges

  13. Corrosion Characteristics of Silicon Carbide and Silicon Nitride

    PubMed Central

    Munro, R. G.; Dapkunas, S. J.

    1993-01-01

    The present work is a review of the substantial effort that has been made to measure and understand the effects of corrosion with respect to the properties, performance, and durability of various forms of silicon carbide and silicon nitride. The review encompasses corrosion in diverse environments, usually at temperatures of 1000 °C or higher. The environments include dry and moist oxygen, mixtures of hot gaseous vapors, molten salts, molten metals, and complex environments pertaining to coal ashes and slags. PMID:28053489

  14. Extracting Silicon From Sodium-Process Products

    NASA Technical Reports Server (NTRS)

    Kapur, V.; Sanjurjo, A.; Sancier, K. M.; Nanis, L.

    1982-01-01

    New acid leaching process purifies silicon produced in reaction between silicon fluoride and sodium. Concentration of sodium fluoride and other impurities and byproducts remaining in silicon are within acceptable ranges for semi-conductor devices. Leaching process makes sodium reduction process more attractive for making large quantities of silicon for solar cells.

  15. Thermal and Kerr nonlinear properties of plasma-deposited silicon nitride/ silicon dioxide waveguides.

    PubMed

    Ikeda, Kazuhiro; Saperstein, Robert E; Alic, Nikola; Fainman, Yeshaiahu

    2008-08-18

    We introduce and present experimental evaluations of loss and nonlinear optical response in a waveguide and an optical resonator, both implemented with a silicon nitride/ silicon dioxide material platform prepared by plasma-enhanced chemical vapor deposition with dual frequency reactors that significantly reduce the stress and the consequent loss of the devices. We measure a relatively small loss of approximately 4dB/cm in the waveguides. The fabricated ring resonators in add-drop and all-pass arrangements demonstrate quality factors of Q=12,900 and 35,600. The resonators are used to measure both the thermal and ultrafast Kerr nonlinearities. The measured thermal nonlinearity is larger than expected, which is attributed to slower heat dissipation in the plasma-deposited silicon dioxide film. The n2 for silicon nitride that is unknown in the literature is measured, for the first time, as 2.4 x 10(-15)cm(2)/W, which is 10 times larger than that for silicon dioxide.

  16. Colloidal characterization of silicon nitride and silicon carbide

    NASA Technical Reports Server (NTRS)

    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.

  17. Micromachining of silicon carbide on silicon fabricated by low-pressure chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Behrens, Ingo; Peiner, Erwin; Bakin, Andrey S.; Schlachetzki, Andreas

    2002-07-01

    We describe the fabrication of silicon carbide layers for micromechanical applications using low-pressure metal-organic chemical vapour deposition at temperatures below 1000 °C. The layers can be structured by lift-off using silicon dioxide as a sacrificial layer. A large selectivity with respect to silicon can be exploited for bulk micromachining. Thin membranes are fabricated which exhibit high mechanical quality, as necessary for applications in harsh environments.

  18. Pinpoint and bulk electrochemical reduction of insulating silicon dioxide to silicon.

    PubMed

    Nohira, Toshiyuki; Yasuda, Kouji; Ito, Yasuhiko

    2003-06-01

    Silicon dioxide (SiO(2)) is conventionally reduced to silicon by carbothermal reduction, in which the oxygen is removed by a heterogeneous-homogeneous reaction sequence at approximately 1,700 degrees C. Here we report pinpoint and bulk electrochemical methods for removing oxygen from solid SiO(2) in a molten CaCl(2) electrolyte at 850 degrees C. This approach involves a 'contacting electrode', in which a metal wire supplies electrons to a selected region of the insulating SiO(2). Bulk reduction of SiO(2) is possible by increasing the number of contacting points. The same method was also demonstrated with molten LiCl-KCl-CaCl(2) at 500 degrees C. The novelty and relative simplicity of this method might lead to new processes in silicon semiconductor technology, as well as in high-purity silicon production. The methodology may be applicable to electrochemical processing of a wide variety of insulating materials, provided that the electrolyte dissolves the appropriate constituent ion(s) of the material.

  19. Enhanced Raman scattering in porous silicon grating.

    PubMed

    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.

  20. Evaluation of Porous Silicon Oxide on Silicon Microcantilevers for Sensitive Detection of Gaseous HF.

    PubMed

    Wallace, Ryan A; Sepaniak, Michael J; Lavrik, Nickolay V; Datskos, Panos G

    2017-06-06

    Sensitive detection of harmful chemicals in industrial applications is pertinent to safety. In this work, we demonstrate the use of a sensitive silicon microcantilever (MC) system with a porous silicon oxide layer deposited on the active side of the MCs that have been mechanically manipulated to increase sensitivity. Included is the evaluation of porous silicon oxide present on different geometries of MCs and exposed to varying concentrations of hydrogen fluoride in humid air. Profilometry and the signal generated by the stress-induced porous silicon oxide (PSO) coating and bending of the MC were used as methods of evaluation.

  1. Evaluation of Porous Silicon Oxide on Silicon Microcantilevers for Sensitive Detection of Gaseous HF

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wallace, Ryan A.; Sepaniak, Michael J.; Lavrik, Nickolay V.

    Sensitive detection of harmful chemicals in industrial applications is pertinent to safety. In this paper, we demonstrate the use of a sensitive silicon microcantilever (MC) system with a porous silicon oxide layer deposited on the active side of the MCs that have been mechanically manipulated to increase sensitivity. Included is the evaluation of porous silicon oxide present on different geometries of MCs and exposed to varying concentrations of hydrogen fluoride in humid air. Finally, profilometry and the signal generated by the stress-induced porous silicon oxide (PSO) coating and bending of the MC were used as methods of evaluation.

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

    PubMed

    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.

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

    PubMed Central

    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

  4. Evaluation of Porous Silicon Oxide on Silicon Microcantilevers for Sensitive Detection of Gaseous HF

    DOE PAGES

    Wallace, Ryan A.; Sepaniak, Michael J.; Lavrik, Nickolay V.; ...

    2017-05-10

    Sensitive detection of harmful chemicals in industrial applications is pertinent to safety. In this paper, we demonstrate the use of a sensitive silicon microcantilever (MC) system with a porous silicon oxide layer deposited on the active side of the MCs that have been mechanically manipulated to increase sensitivity. Included is the evaluation of porous silicon oxide present on different geometries of MCs and exposed to varying concentrations of hydrogen fluoride in humid air. Finally, profilometry and the signal generated by the stress-induced porous silicon oxide (PSO) coating and bending of the MC were used as methods of evaluation.

  5. Methods for producing silicon carbide fibers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Garnier, John E.; Griffith, George W.

    Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

  6. Silicon Technologies Adjust to RF Applications

    NASA Technical Reports Server (NTRS)

    Reinecke Taub, Susan; Alterovitz, Samuel A.

    1994-01-01

    Silicon (Si), although not traditionally the material of choice for RF and microwave applications, has become a serious challenger to other semiconductor technologies for high-frequency applications. Fine-line electron- beam and photolithographic techniques are now capable of fabricating silicon gate sizes as small as 0.1 micron while commonly-available high-resistivity silicon wafers support low-loss microwave transmission lines. These advances, coupled with the recent development of silicon-germanium (SiGe), arm silicon integrated circuits (ICs) with the speed required for increasingly higher-frequency applications.

  7. Ultrasonic Measurement Of Silicon-Growth Interface

    NASA Technical Reports Server (NTRS)

    Heyser, Richard C.

    1988-01-01

    Position of interface between silicon melt and growing ribbon of silicon measured with aid of reflected ultrasound, according to proposal. Reflections reveal characteristics of ribbon and melt. Ultrasound pulses travel through rods to silicon ribbon growing by dendritic-web process. Rods return reflections of pulses to sonic transducers. Isolate transducers thermally, but not acoustically, from hot silicon melt.

  8. Adjustable Lid Aids Silicon-Ribbon Growth

    NASA Technical Reports Server (NTRS)

    Mchugh, J. P.; Steidensticker, R. G.; Duncan, C. S.

    1985-01-01

    Closely-spaced crucible cover speeds up solidification. Growth rate of dendritic-web silicon ribbon from molten silicon increased by controlling distance between crucible susceptor lid and liquid/solid interface. Lid held in relatively high position when crucible newly filled with chunks of polycrystalline silicon. As silicon melts and forms pool of liquid at lower level, lid gradually lowered.

  9. High purity silane and silicon production

    NASA Technical Reports Server (NTRS)

    Breneman, William C. (Inventor)

    1987-01-01

    Silicon tetrachloride, hydrogen and metallurgical silicon are reacted at about 400.degree.-600.degree. C. and at pressures in excess of 100 psi, and specifically from about 300 up to about 600 psi to form di- and trichlorosilane that is subjected to disproportionation in the presence of an anion exchange resin to form high purity silane. By-product and unreacted materials are recycled, with metallurgical silicon and hydrogen being essentially the only consumed feed materials. The silane product may be further purified, as by means of activated carbon or cryogenic distillation, and decomposed in a fluid bed or free space reactor to form high purity polycrystalline silicon and by-product hydrogen which can be recycled for further use. The process results in simplified waste disposal operations and enhances the overall conversion of metallurgical grade silicon to silane and high purity silicon for solar cell and semiconductor silicon applications.

  10. Synthesis and devolatilization of M-97 NVB silicone gum compounded into silica reinforced silicone base

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schneider, J.W.

    1986-06-01

    Silica reinforced silicon bases having 0.31 weight percent vinyl content were prepared by using a blend of low and high vinyl content devolatilized M-97 NVB silicone gum. The M-97 NVB is a custom dimethyl-, diphenyl-, methylvinylsiloxane gum. The silicon gum was devolatilized to evaluate the anticipated improved handling characteristics. Previous procured batches of M-97 NVB had not been devolatilized and difficult handling problems were encountered. The synthesis, devolatilization, and compound processes for the M-97 NVB silicone gum are discussed.

  11. Synthesis and characterization of silicon nanorod on n-type porous silicon.

    PubMed

    Behzad, Kasra; Mat Yunus, Wan Mahmood; Bahrami, Afarin; Kharazmi, Alireza; Soltani, Nayereh

    2016-03-20

    This work reports a new method for growing semiconductor nanorods on a porous silicon substrate. After preparation of n-type porous silicon samples, a thin layer of gold was deposited on them. Gold deposited samples were annealed at different temperatures. The structural, thermal, and optical properties of the samples were studied using a field emission scanning electron microscope (FESEM), photoacoustic spectroscopy, and photoluminescence spectroscopy, respectively. FESEM analysis revealed that silicon nanorods of different sizes grew on the annealed samples. Thermal behavior of the samples was studied using photoacoustic spectroscopy. Photoluminescence spectroscopy showed that the emission peaks were degraded by gold deposition and attenuated for all samples by annealing.

  12. Determination of Silicon in Hydrazine

    NASA Technical Reports Server (NTRS)

    McClure, Mark B.; Mast, Dion; Greene, Ben; Maes, Miguel J.

    2006-01-01

    Inductively coupled plasma-mass spectrometry (ICP-MS) is a highly sensitive technique sometimes used for the trace determination of silicon at a mass-to-charge (m/z) ratio of 28, the most abundant natural isotope of silicon. Unfortunately, ICP-MS is unable to differentiate between other sources of m/z 28 and false positive results for silicon will result when other sources of m/z 28 are present. Nitrogen was a major source of m/z 28 and contributes to the m/z 28 signal when hydrazine sample or nitric acid preservative is introduced into the plasma. Accordingly, this work was performed to develop a sample preparation step coupled with an ICP-MS analysis that minimized non-silicon sources of m/z 28. In the preparatory step of this method, the hydrazine sample was first decomposed predominately to nitrogen gas and water with copper-catalyzed hydrogen peroxide. In the analysis step, ICP-MS was used without nitric acid preservative in samples or standards. Glass, a potential source of silicon contamination, was also avoided where possible. The method was sensitive, accurate, and reliable for the determination of silicon in monopropellant grade hydrazine (MPH) in AF-E-332 elastomer leaching tests. Results for silicon in MPH were comparable to those reported in the literature for other studies.

  13. High specific activity silicon-32

    DOEpatents

    Phillips, Dennis R.; Brzezinski, Mark A.

    1996-01-01

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  14. High specific activity silicon-32

    DOEpatents

    Phillips, D.R.; Brzezinski, M.A.

    1996-06-11

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidation state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  15. Silicon quantum dots for energetic material applications

    NASA Astrophysics Data System (ADS)

    Adams, Sarah K.; Piekiel, Nicholas W.; Ervin, Matthew H.; Morris, Christopher J.

    2018-06-01

    In its history as an energetic material, porous silicon has demonstrated flame speeds in excess of 3 km s-1, tunable combustion behavior, and high energy output, which in theory makes it a very attractive energetic system. In practice, its application within the field is limited by porous silicon's typical substrate-adhered form and caustic chemical processing requirements that limit how and when porous silicon is made. In this work, we have relieved porous silicon of these constraints by creating reactive silicon quantum dots from free-standing porous silicon films. The resulting material is composed of crystalline silicon nanoparticles with diameters as small as 2 nm that retain the chemical properties of the original films including the SiH2 termination layer. The fabricated silicon particles were characterized using FTIR Spectroscopy, TEM, and EDS for determining the size and the chemical composition. For testing as an energetic material fuel, porous silicon was mixed with an oft used oxidizer, sodium perchlorate. During open-channel combustion tests, silicon quantum dots mixed with sodium perchlorate demonstrated flame speeds over 2.5 km s-1, while bomb calorimetry tests showed an average heat of combustion of 7.4 kJ g-1. These results demonstrate the ability to retain the porous silicon material properties that allow for highly energetic material reactions to occur, despite the additional processing steps to create silicon quantum dots. This opens the door for the use of porous silicon in the bulk of the energetic material application space, much of which was previously limited due to the substrate-attached nature of typical porous silicon.

  16. Silicon nanocrystal inks, films, and methods

    DOEpatents

    Wheeler, Lance Michael; Kortshagen, Uwe Richard

    2015-09-01

    Silicon nanocrystal inks and films, and methods of making and using silicon nanocrystal inks and films, are disclosed herein. In certain embodiments the nanocrystal inks and films include halide-terminated (e.g., chloride-terminated) and/or halide and hydrogen-terminated nanocrystals of silicon or alloys thereof. Silicon nanocrystal inks and films can be used, for example, to prepare semiconductor devices.

  17. Process for forming retrograde profiles in silicon

    DOEpatents

    Weiner, K.H.; Sigmon, T.W.

    1996-10-15

    A process is disclosed for forming retrograde and oscillatory profiles in crystalline and polycrystalline silicon. The process consisting of introducing an n- or p-type dopant into the silicon, or using prior doped silicon, then exposing the silicon to multiple pulses of a high-intensity laser or other appropriate energy source that melts the silicon for short time duration. Depending on the number of laser pulses directed at the silicon, retrograde profiles with peak/surface dopant concentrations which vary are produced. The laser treatment can be performed in air or in vacuum, with the silicon at room temperature or heated to a selected temperature.

  18. Metallic coatings on silicon substrates, and methods of forming metallic coatings on silicon substrates

    DOEpatents

    Branagan, Daniel J [Idaho Falls, ID; Hyde, Timothy A [Idaho Falls, ID; Fincke, James R [Los Alamos, NM

    2008-03-11

    The invention includes methods of forming a metallic coating on a substrate which contains silicon. A metallic glass layer is formed over a silicon surface of the substrate. The invention includes methods of protecting a silicon substrate. The substrate is provided within a deposition chamber along with a deposition target. Material from the deposition target is deposited over at least a portion of the silicon substrate to form a protective layer or structure which contains metallic glass. The metallic glass comprises iron and one or more of B, Si, P and C. The invention includes structures which have a substrate containing silicon and a metallic layer over the substrate. The metallic layer contains less than or equal to about 2 weight % carbon and has a hardness of at least 9.2 GPa. The metallic layer can have an amorphous microstructure or can be devitrified to have a nanocrystalline microstructure.

  19. Chemical vapor deposition of silicon, silicon dioxide, titanium and ferroelectric thin films

    NASA Astrophysics Data System (ADS)

    Chen, Feng

    Various silicon-based thin films (such as epitaxial, polycrystalline and amorphous silicon thin films, silicon dioxide thin films and silicon nitride thin films), titanium thin film and various ferroelectric thin films (such as BaTiO3 and PbTiO3 thin films) play critical roles in the manufacture of microelectronics circuits. For the past few years, there have been tremendous interests to search for cheap, safe and easy-to-use methods to develop those thin films with high quality and good step coverage. Silane is a critical chemical reagent widely used to deposit silicon-based thin films. Despite its wide use, silane is a dangerous material. It is pyrophoric, extremely flammable and may explode from heat, shock and/or friction. Because of the nature of silane, serious safety issues have been raised concerning the use, transportation, and storage of compressed gas cylinders of silane. Therefore it is desired to develop safer ways to deposit silicon-based films. In chapter III, I present the results of our research in the following fields: (1) Silane generator, (2) Substitutes of silane for deposition of silicon and silicon dioxide thin films, (3) Substitutes of silane for silicon dioxide thin film deposition. In chapter IV, hydropyridine is introduced as a new ligand for use in constructing precursors for chemical vapor deposition. Detachement of hydropyridine occurs by a low-temperature reaction leaving hydrogen in place of the hydropyridine ligands. Hydropyridine ligands can be attached to a variety of elements, including main group metals, such as aluminum and antimony, transition metals, such as titanium and tantalum, semiconductors such as silicon, and non-metals such as phosphorus and arsenic. In this study, hydropyridine-containing titanium compounds were synthesized and used as chemical vapor deposition precursors for deposition of titanium containing thin films. Some other titanium compounds were also studied for comparison. In chapter V, Chemical Vapor

  20. Cleaning up Silicon

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A development program that started in 1975 between Union Carbide and JPL, led to Advanced Silicon Materials LLC's, formerly ASiMI, commercial process for producing silane in viable quantities. The process was expanded to include the production of high-purity polysilicon for electronic devices. The technology came out of JPL's Low Cost Silicon Array Project.

  1. A 2-terminal perovskite/silicon multijunction solar cell enabled by a silicon tunnel junction

    DOE PAGES

    Mailoa, Jonathan P.; Bailie, Colin D.; Johlin, Eric C.; ...

    2015-03-24

    With the advent of efficient high-bandgap metal-halide perovskite photovoltaics, an opportunity exists to make perovskite/silicon tandem solar cells. We fabricate a monolithic tandem by developing a silicon-based interband tunnel junction that facilitates majority-carrier charge recombination between the perovskite and silicon sub-cells. We demonstrate a 1 cm 2 2-terminal monolithic perovskite/silicon multijunction solar cell with a V OC as high as 1.65 V. As a result, we achieve a stable 13.7% power conversion efficiency with the perovskite as the current-limiting sub-cell, and identify key challenges for this device architecture to reach efficiencies over 25%.

  2. Polycrystalline silicon on tungsten substrates

    NASA Technical Reports Server (NTRS)

    Bevolo, A. J.; Schmidt, F. A.; Shanks, H. R.; Campisi, G. J.

    1979-01-01

    Thin films of electron-beam-vaporized silicon were deposited on fine-grained tungsten substrates under a pressure of about 1 x 10 to the -10th torr. Mass spectra from a quadrupole residual-gas analyzer were used to determine the partial pressure of 13 residual gases during each processing step. During separate silicon depositions, the atomically clean substrates were maintained at various temperatures between 400 and 780 C, and deposition rates were between 20 and 630 A min. Surface contamination and interdiffusion were monitored by in situ Auger electron spectrometry before and after cleaning, deposition, and annealing. Auger depth profiling, X-ray analysis, and SEM in the topographic and channeling modes were utilized to characterize the samples with respect to silicon-metal interface, interdiffusion, silicide formation, and grain size of silicon. The onset of silicide formation was found to occur at approximately 625 C. Above this temperature tungsten silicides were formed at a rate faster than the silicon deposition. Fine-grain silicon films were obtained at lower temperatures.

  3. Solar silicon via improved and expanded metallurgical silicon technology

    NASA Technical Reports Server (NTRS)

    Hunt, L. P.; Dosaj, V. D.; Mccormick, J. R.

    1977-01-01

    A completed preliminary survey of silica sources indicates that sufficient quantities of high-purity quartz are available in the U.S. and Canada to meet goals. Supply can easily meet demand for this little-sought commodity. Charcoal, as a reductant for silica, can be purified to a sufficient level by high-temperature fluorocarbon treatment and vacuum processing. High-temperature treatment causes partial graphitization which can lead to difficulty in smelting. Smelting of Arkansas quartz and purified charcoal produced kilogram quantities of silicon having impurity levels generally much lower than in MG-Si. Half of the goal was met of increasing the boron resistivity from 0.03 ohm-cm in metallurgical silicon to 0.3 ohm-cm in solar silicon. A cost analysis of the solidification process indicate $3.50-7.25/kg Si for the Czochralski-type process and $1.50-4.25/kg Si for the Bridgman-type technique.

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

    DOEpatents

    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.

  5. Short Shot Tower for Silicon

    NASA Technical Reports Server (NTRS)

    Bates, H. E.; Hill, D. M.; Jewett, D. N.

    1983-01-01

    Drop length necessary to convert molten silicon to shot reduced by proposed new process. Conversion of silicon from powder or chunks to shot often simplifies processing. Shot is more easily handled in most processing equipment. Drops of liquid silicon fall through protective cloud of argon, then through rapidly cooling bath of methanol, where they quickly turn into solid shot.

  6. Hybrid Integrated Platforms for Silicon Photonics

    PubMed Central

    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.

  7. Epitaxial growth of silicon for layer transfer

    DOEpatents

    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.

  8. Gamma radiation effects on silicon photonic waveguides.

    PubMed

    Grillanda, Stefano; Singh, Vivek; Raghunathan, Vivek; Morichetti, Francesco; Melloni, Andrea; Kimerling, Lionel; Agarwal, Anuradha M

    2016-07-01

    To support the use of integrated photonics in harsh environments, such as outer space, the hardness threshold to high-energy radiation must be established. Here, we investigate the effects of gamma (γ) rays, with energy in the MeV-range, on silicon photonic waveguides. By irradiation of high-quality factor amorphous silicon core resonators, we measure the impact of γ rays on the materials incorporated in our waveguide system, namely amorphous silicon, silicon dioxide, and polymer. While we show the robustness of amorphous silicon and silicon dioxide up to an absorbed dose of 15 Mrad, more than 100× higher than previous reports on crystalline silicon, polymer materials exhibit changes with doses as low as 1 Mrad.

  9. Silicon crystal growth in vacuum

    NASA Technical Reports Server (NTRS)

    Khattak, C. P.; Schmid, F.

    1982-01-01

    The most developed process for silicon crystal growth is the Czochralski (CZ) method which was in production for over two decades. In an effort to reduce cost of single crystal silicon for photovoltaic applications, a directional solidification technique, Heat Exchanger Method (HEM), was adapted. Materials used in HEM and CZ furnaces are quite similar (heaters, crucibles, insulation, etc.). To eliminate the cost of high purity argon, it was intended to use vacuum operation in HEM. Two of the major problems encountered in vacuum processing of silicon are crucible decomposition and silicon carbide formation in the melt.

  10. Silicon Qubits

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ladd, Thaddeus D.; Carroll, Malcolm S.

    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 amore » 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.« less

  11. Microstructured silicon radiation detector

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Okandan, Murat; Derzon, Mark S.; Draper, Bruce L.

    2017-03-14

    A radiation detector comprises a silicon body in which are defined vertical pores filled with a converter material and situated within silicon depletion regions. One or more charge-collection electrodes are arranged to collect current generated when secondary particles enter the silicon body through walls of the pores. The pores are disposed in low-density clusters, have a majority pore thickness of 5 .mu.m or less, and have a majority aspect ratio, defined as the ratio of pore depth to pore thickness, of at least 10.

  12. Recrystallization of polycrystalline silicon

    NASA Technical Reports Server (NTRS)

    Lall, C.; Kulkarni, S. B.; Graham, C. D., Jr.; Pope, D. P.

    1981-01-01

    Optical metallography is used to investigate the recrystallization properties of polycrystalline semiconductor-grade silicon. It is found that polycrystalline silicon recrystallizes at 1380 C in relatively short times, provided that the prior deformation is greater than 30%. For a prior deformation of about 40%, the recrystallization process is essentially complete in about 30 minutes. Silicon recrystallizes at a substantially slower rate than metals at equivalent homologous temperatures. The recrystallized grain size is insensitive to the amount of prestrain for strains in the range of 10-50%.

  13. Prevention of postsurgical scars: comparsion of efficacy and convenience between silicone gel sheet and topical silicone gel.

    PubMed

    Kim, Sue-Min; Choi, Jung-Sik; Lee, Jung-Ho; Kim, Young-Jin; Jun, Young-Joon

    2014-11-01

    To date, few studies have compared the effectiveness of topical silicone gels versus that of silicone gel sheets in preventing scars. In this prospective study, we compared the efficacy and the convenience of use of the 2 products. We enrolled 30 patients who had undergone a surgical procedure 2 weeks to 3 months before joining the study. These participants were randomly assigned to 2 treatment arms: one for treatment with a silicone gel sheet, and the other for treatment with a topical silicone gel. Vancouver Scar Scale (VSS) scores were obtained for all patients; in addition, participants completed scoring patient questionnaires 1 and 3 months after treatment onset. Our results reveal not only that no significant difference in efficacy exists between the 2 products but also that topical silicone gels are more convenient to use. While previous studies have advocated for silicone gel sheets as first-line therapies in postoperative scar management, we maintain that similar effects can be expected with topical silicone gel. The authors recommend that, when clinicians have a choice of silicone-based products for scar prevention, they should focus on each patient's scar location, lifestyle, and willingness to undergo scar prevention treatment.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Bei; Ahmed, Mohsin; Iacopi, Francesca, E-mail: f.iacopi@griffith.edu.au

    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 capacitancemore » 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.« less

  15. Mitotic trafficking of silicon microparticles†

    PubMed Central

    Serda, Rita E.; Ferrati, Silvia; Godin, Biana; Tasciotti, Ennio; Liu, XueWu

    2010-01-01

    Multistage carriers were recently introduced by our laboratory, with the concurrent objectives of co-localized delivery of multiple therapeutic agents, the “theranostic” integration of bioactive moieties with imaging contrast, and the selective, potentially personalized bypassing of the multiplicity of biological barriers that adversely impact biodistribution of vascularly injected particulates. Mesoporous (“nanoporous”) silicon microparticles were selected as primary carriers in multi-stage devices, with targets including vascular endothelia at pathological lesions. The objective of this study was to evaluate biocompatibility of mesoporous silicon microparticles with endothelial cells using in vitro assays with an emphasis on microparticle compatibility with mitotic events. We observed that vascular endothelial cells, following internalization of silicon microparticles, maintain cellular integrity, as demonstrated by cellular morphology, viability and intact mitotic trafficking of vesicles bearing silicon microparticles. The presence of gold or iron oxide nanoparticles within the porous matrix did not alter the cellular uptake of particles or the viability of endothelial cells subsequent to engulfment of microparticles. Endothelial cells maintained basal levels of IL-6 and IL-8 release in the presence of silicon microparticles. This is the first study that demonstrates polarized, ordered partitioning of endosomes based on tracking microparticles. The finding that mitotic sorting of endosomes is unencumbered by the presence of nanoporous silicon microparticles advocates the use of silicon microparticles for biomedical applications. PMID:20644846

  16. Dip-coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Zook, J. D.; Heaps, J. D.; Maciolek, R. B.; Koepke, B. G.; Gutter, C. D.; Schuldt, S. B.

    1977-01-01

    The objective of this research program is to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. The past quarter demonstrated significant progress in several areas. Seeded growth of silicon-on-ceramic (SOC) with an EFG ribbon seed was demonstrated. Different types of mullite were successfully coated with silicon. A new method of deriving minority carrier diffusion length, L sub n from spectral response measurements was evaluated. ECOMOD cost projections were found to be in good agreement with the interim SAMIS method proposed by JPL. On the less positive side, there was a decrease in cell performance which we believe to be due to an unidentified source of impurities.

  17. Pentosanpolysulfate coating of silicone reduces encrustation.

    PubMed

    Zupkas, P; Parsons, C L; Percival, C; Monga, M

    2000-08-01

    A significant problem associated with catheterization in the urinary tract is the encrustation of the catheter materials. One approach to reducing encrustation is to alter the surface properties of the catheters. We evaluated the effectiveness of coating with pentosanpolysulfate (PPS), a semisynthetic polysaccharide similar to heparin, in reducing encrustation and the foreign-body inflammatory response to silicone stents in the bladders of male New Zealand White rabbits. Sixteen rabbits were divided into three groups to receive placement in their bladders of uncoated (N = 7), PPS-coated (N = 7), or sham matrix-processed silicone rings (N = 2) via open cystotomy. After 50 days of maintenance on normal food and water, all rabbits were sacrificed, and the air-dried, unfixed silicone ring surfaces were examined by scanning electron microscopy. Bladders and remaining silicone rings were removed and preserved separately. Silicone rings, cleaned of all encrustation, were stained with toluidene blue to determine the presence or absence of PPS coating on the surface. Histologic examination revealed normal tissue in bladder sections exposed to coated silicone rings and an inflammatory response in sections from bladders having uncoated silicone rings. Coating with PPS was associated with an eightfold reduction in the amount of encrustation of silicone and a marked reduction in the inflammatory response of the bladder wall to the foreign body. A PPS coating may be useful in reducing the encrustation of long-term indwelling silicone stents or catheters in the human urinary tract.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Silicon micromachined vibrating gyroscopes

    NASA Astrophysics Data System (ADS)

    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.

  20. Mode-converting coupler for silicon-on-sapphire devices

    NASA Astrophysics Data System (ADS)

    Zlatanovic, S.; Offord, B. W.; Owen, M.; Shimabukuro, R.; Jacobs, E. W.

    2015-02-01

    Silicon-on-sapphire devices are attractive for the mid-infrared optical applications up to 5 microns due to the low loss of both silicon and sapphire in this wavelength band. Designing efficient couplers for silicon-on-sapphire devices presents a challenge due to a highly confined mode in silicon and large values of refractive index of both silicon and sapphire. Here, we present design, fabrication, and measurements of a mode-converting coupler for silicon-on-sapphire waveguides. We utilize a mode converter layout that consists of a large waveguide that is overlays a silicon inverse tapered waveguide. While this geometry was previously utilized for silicon-on-oxide devices, the novelty is in using materials that are compatible with the silicon-on-sapphire platform. In the current coupler the overlaying waveguide is made of silicon nitride. Silicon nitride is the material of choice because of the large index of refraction and low absorption from near-infrared to mid-infrared. The couplers were fabricated using a 0.25 micron silicon-on-sapphire process. The measured coupling loss from tapered lensed silica fibers to the silicon was 4.8dB/coupler. We will describe some challenges in fabrication process and discuss ways to overcome them.

  1. Method for processing silicon solar cells

    DOEpatents

    Tsuo, Y.S.; Landry, M.D.; Pitts, J.R.

    1997-05-06

    The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystalline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation. 2 figs.

  2. Method for processing silicon solar cells

    DOEpatents

    Tsuo, Y. Simon; Landry, Marc D.; Pitts, John R.

    1997-01-01

    The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystallline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation.

  3. Transmutation doping of silicon solar cells

    NASA Technical Reports Server (NTRS)

    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.

  4. Anisotropic Tribological Properties of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1980-01-01

    The anisotropic friction, deformation and fracture behavior of single crystal silicon carbide surfaces were investigated in two categories. The categories were called adhesive and abrasive wear processes, respectively. In the adhesive wear process, the adhesion, friction and wear of silicon carbide were markedly dependent on crystallographic orientation. The force to reestablish the shearing fracture of adhesive bond at the interface between silicon carbide and metal was the lowest in the preferred orientation of silicon carbide slip system. The fracturing of silicon carbide occurred near the adhesive bond to metal and it was due to primary cleavages of both prismatic (10(-1)0) and basal (0001) planes.

  5. Silicon on insulator self-aligned transistors

    DOEpatents

    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.

  6. Creep analysis of silicone for podiatry applications.

    PubMed

    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.

  7. Three dimensional amorphous silicon/microcrystalline silicon solar cells

    DOEpatents

    Kaschmitter, James L.

    1996-01-01

    Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/.mu.c-Si) solar cells which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell.

  8. Three dimensional amorphous silicon/microcrystalline silicon solar cells

    DOEpatents

    Kaschmitter, J.L.

    1996-07-23

    Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/{micro}c-Si) solar cells are disclosed which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell. 4 figs.

  9. Confined in-fiber solidification and structural control of silicon and silicon-germanium microparticles.

    PubMed

    Gumennik, Alexander; Levy, Etgar C; Grena, Benjamin; Hou, Chong; Rein, Michael; Abouraddy, Ayman F; Joannopoulos, John D; Fink, Yoel

    2017-07-11

    Crystallization of microdroplets of molten alloys could, in principle, present a number of possible morphological outcomes, depending on the symmetry of the propagating solidification front and its velocity, such as axial or spherically symmetric species segregation. However, because of thermal or constitutional supercooling, resulting droplets often only display dendritic morphologies. Here we report on the crystallization of alloyed droplets of controlled micrometer dimensions comprising silicon and germanium, leading to a number of surprising outcomes. We first produce an array of silicon-germanium particles embedded in silica, through capillary breakup of an alloy-core silica-cladding fiber. Heating and subsequent controlled cooling of individual particles with a two-wavelength laser setup allows us to realize two different morphologies, the first being a silicon-germanium compositionally segregated Janus particle oriented with respect to the illumination axis and the second being a sphere made of dendrites of germanium in silicon. Gigapascal-level compressive stresses are measured within pure silicon solidified in silica as a direct consequence of volume-constrained solidification of a material undergoing anomalous expansion. The ability to generate microspheres with controlled morphology and unusual stresses could pave the way toward advanced integrated in-fiber electronic or optoelectronic devices.

  10. Process for forming silicon carbide films and microcomponents

    DOEpatents

    Hamza, A.V.; Balooch, M.; Moalem, M.

    1999-01-19

    Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C{sub 60} precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C{sub 60} with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C{sub 60} on silicon dioxide at surface temperatures less than 1250 K. 5 figs.

  11. Process for forming silicon carbide films and microcomponents

    DOEpatents

    Hamza, Alex V.; Balooch, Mehdi; Moalem, Mehran

    1999-01-01

    Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C.sub.60 precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C.sub.60 with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C.sub.60 on silicon dioxide at surface temperatures less than 1250 K.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. High-Temperature Annealing as a Method for the Silicon Nanoclusters Growth in Stoichiometric Silicon Dioxide

    NASA Astrophysics Data System (ADS)

    Ivanova, E. V.; Dementev, P. A.; Sitnikova, A. A.; Aleksandrov, O. V.; Zamoryanskaya, M. V.

    2018-07-01

    A method for the growth of nanocomposite layers in stoichiometric amorphous silicon dioxide is proposed. It is shown that, after annealing at a temperature of 1150°C in nitrogen atmosphere, a layer containing silicon nanoclusters is formed. Silicon nanoclusters have a crystal structure and a size of 3-6 nm. In a film grown on a n-type substrate, a layer of silicon nanoclusters with a thickness of about 10 nm is observed. In the case of a film grown on a p-type substrate, a nanocomposite layer with a thickness of about 100 nm is observed. The difference in the formation of a nanocomposite layer in films on various substrates is associated with the doping of silicon dioxide with impurities from the substrate during the growth of the film. The formation of the nanocomposite layer was confirmed by transmission electron microscopy, XPS and local cathodoluminescence studies.

  14. Dynamic Silicon Nanophotonics

    DTIC Science & Technology

    2013-07-31

    sensitive to fabrication imperfections and small temperature changes, therefore they are challenging to integrate into high yield mass production ... Cocoa Beach, Florida, September 2012. 15. Ali Wanis Elshaari, “Photon Manipulation in Silicon Nanophotonic Circuits,” Ph.D. Dissertation, Rochester...1.5-micron Light using Silicon Nanocrystals,” 2012 IEEE Avionics, Fiber Optics and Photonics Conference (AVFOP 2012), ThB3, Cocoa Beach, Florida

  15. Preventing Freezeup in Silicon Ribbon Growth

    NASA Technical Reports Server (NTRS)

    Mackintosh, B.

    1983-01-01

    Carefully-shaped heat conductor helps control thermal gradients crucial to growth of single-crystal silicon sheets for solar cells. Ends of die through which silicon sheet is drawn as ribbon from molten silicon. Profiled heat extractor prevents ribbon ends from solidifying prematurely and breaking.

  16. Silicon nitride sintered body

    NASA Technical Reports Server (NTRS)

    Suzuki, K.; Shinohara, N.

    1984-01-01

    The sintering of silicon carbide and it production are described. The method of production is by calcination in which molding is followed by sintering without compression. The invention improves the composition of the silicon carbide ceramic. Six examples of the invention are illustrated and discussed.

  17. Silicon carbide ceramic production

    NASA Technical Reports Server (NTRS)

    Suzuki, K.; Shinohara, N.

    1984-01-01

    A method to produce sintered silicon carbide ceramics in which powdery carbonaceous components with a dispersant are mixed with silicon carbide powder, shaped as required with or without drying, and fired in nonoxidation atmosphere is described. Carbon black is used as the carbonaceous component.

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

    PubMed

    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.

  19. Studies of SERS efficiency of gold coated porous silicon formed on rough silicon backside

    NASA Astrophysics Data System (ADS)

    Dridi, H.; Haji, L.; Moadhen, A.

    2017-12-01

    Starting from a rough backside of silicon wafer, we have formed a porous layer by electrochemical anodization and then coated by a thin film of gold. The morphological characteristics of the porous silicon and in turn the metal film are governed by the anodization process and also by the starting surface. So, in order to investigate the Plasmonic aspect of such rough surface which combines roughness inherent to the porous nature and that due to rough starting surface, we have used a dye target molecule to study its SERS signal using a porous silicon layer obtained on the rough backside surface. The use of unusual backside of silicon wafer could be, beside the others, an interesting way to made SERS effective substrate thanks to reproducible rough porous gold on porous layer from this starting face. The morphological results correspond to the silicon rough surface as a function of the crystallographic orientation showed the presence of two different substrate structure. The optical reflectivity results obtained of gold deposited on oxidized porous silicon showed a dependence of its Localized Surface Plasmon band frequency of the deposit time. SERS results, obtained for a dye target molecule (Rhodamine 6G), show a higher intensities in the case of the 〈110〉 orientation, which characterized by the higher roughness surface. Voici "the most relevant and important aspects of our work".

  20. Light-induced changes in silicon nanocrystal based solar cells: Modification of silicon-hydrogen bonding on silicon nanocrystal surface under illumination

    NASA Astrophysics Data System (ADS)

    Kim, Ka-Hyun; Johnson, Erik V.; Cabarrocas, Pere Roca i.

    2016-07-01

    Hydrogenated polymorphous silicon (pm-Si:H) is a material consisting of a small volume fraction of nanocrystals embedded in an amorphous matrix. pm-Si:H solar cells demonstrate interesting initial degradation behaviors such as rapid initial change in photovoltaic parameters and self-healing after degradation during light-soaking. The precise dynamics of the light-induced degradation was studied in a series of light-soaking experiments under various illumination conditions such as AM1.5G and filtered 570 nm yellow light. Hydrogen effusion experiment before and after light-soaking further revealed that the initial degradation of pm-Si:H solar cells originate from the modification of silicon-hydrogen bonding on the surface of silicon nanocrystals in pm-Si:H.

  1. Room temperature visible photoluminescence of silicon nanocrystallites embedded in amorphous silicon carbide matrix

    NASA Astrophysics Data System (ADS)

    Coscia, U.; Ambrosone, G.; Basa, D. K.

    2008-03-01

    The nanocrystalline silicon embedded in amorphous silicon carbide matrix was prepared by varying rf power in high vacuum plasma enhanced chemical vapor deposition system using silane methane gas mixture highly diluted in hydrogen. In this paper, we have studied the evolution of the structural, optical, and electrical properties of this material as a function of rf power. We have observed visible photoluminescence at room temperature and also have discussed the role played by the Si nanocrystallites and the amorphous silicon carbide matrix. The decrease of the nanocrystalline size, responsible for quantum confinement effect, facilitated by the amorphous silicon carbide matrix, is shown to be the primary cause for the increase in the PL intensity, blueshift of the PL peak position, decrease of the PL width (full width at half maximum) as well as the increase of the optical band gap and the decrease of the dark conductivity.

  2. Hybrid III-V/silicon lasers

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  4. Antifuse with a single silicon-rich silicon nitride insulating layer

    DOEpatents

    Habermehl, Scott D.; Apodaca, Roger T.

    2013-01-22

    An antifuse is disclosed which has an electrically-insulating region sandwiched between two electrodes. The electrically-insulating region has a single layer of a non-hydrogenated silicon-rich (i.e. non-stoichiometric) silicon nitride SiN.sub.X with a nitrogen content X which is generally in the range of 0silicon. Arrays of antifuses can also be formed.

  5. Study of properties of modified silicones at solid-liquid interface: fabric-silicone interactions.

    PubMed

    Purohit, P; Somasundaran, P; Kulkarni, R

    2006-06-15

    Silicones are special reagents that impart desired surface properties such as softness, bounciness and antiwrinkle properties to fabrics and related materials. Although these finishing processes have been practiced routinely, very little is known about the mechanisms involved in modification so that they could be improved. The current study was undertaken to develop basic understanding of the mechanisms responsible for surface modification of fibers using silicones. PDMS based amino silicone emulsions, quaternized to various degrees using dimethyl sulphate, were used in the present study. The electrokinetic properties of the modified silicones were studied as a function of pH. It was expected that the silicone emulsions would show a steady positive zeta potential throughout the pH range due to the quaternization by dimethyl sulphate. Surprisingly, a sudden drop in the zeta potential was observed around pH 8 with the samples turning hazy in the pH range of 8-10. Turbidimetric studies also showed a sudden increase in the turbidity in the pH range 8-10 where commercial processes also encounter problems. It was concluded that the emulsions were destabilized at pH 8-10 thus rendering them ineffective for surface treatment. In order to identify reason for the improvement in fabric properties, fiber structure was monitored using atomic force microscopy. It was observed that the treated fibers were far smoother, relaxed and uniform as compared to the untreated fibers. Thus the morphology of the fabric is modified in a specific way by treatment with specialty silicones.

  6. Ultra-Thin Monocrystalline Silicon Solar Cell with 12.2% Efficiency Using Silicon-On-Insulator Substrate.

    PubMed

    Bian, Jian-Tao; Yu, Jian; Duan, Wei-Yuan; Qiu, Yu

    2015-04-01

    Single side heterojunction silicon solar cells were designed and fabricated using Silicon-On-Insulator (SOI) substrate. The TCAD software was used to simulate the effect of silicon layer thickness, doping concentration and the series resistance. A 10.5 µm thick monocrystalline silicon layer was epitaxially grown on the SOI with boron doping concentration of 2 x 10(16) cm(-3) by thermal CVD. Very high Voc of 678 mV was achieved by applying amorphous silicon heterojunction emitter on the front surface. The single cell efficiency of 12.2% was achieved without any light trapping structures. The rear surface recombination and the series resistance are the main limiting factors for the cell efficiency in addition to the c-Si thickness. By integrating an efficient light trapping scheme and further optimizing fabrication process, higher efficiency of 14.0% is expected for this type of cells. It can be applied to integrated circuits on a monolithic chip to meet the requirements of energy autonomous systems.

  7. EDITORIAL: Special issue on silicon photonics

    NASA Astrophysics Data System (ADS)

    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

  8. Silicon carbide fibers and articles including same

    DOEpatents

    Garnier, John E; Griffith, George W

    2015-01-27

    Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

  9. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Black, Marcie

    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.

  10. Process of preparing tritiated porous silicon

    DOEpatents

    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.

  11. Sources and transport of silicone NVR

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1992-01-01

    The retrieved LDEF had varying amounts of visible contamination films (brown stains) at many locations. FTIR spectra of heavy film deposits at vents and of optical windows from tray E5 indicated methyl silicone and silica in the contaminant films. Two possible sources of the methyl silicone are DC-710 phenyl methyl silicone in the shuttle-bay-liner beta cloth, and the shuttle tile waterproofing silane. It is concluded that much of the silicon and silica contamination came from ground operations and the orbiter.

  12. Silicon photonics and challenges for fabrication

    NASA Astrophysics Data System (ADS)

    Feilchenfeld, N. B.; Nummy, K.; Barwicz, T.; Gill, D.; Kiewra, E.; Leidy, R.; Orcutt, J. S.; Rosenberg, J.; Stricker, A. D.; Whiting, C.; Ayala, J.; Cucci, B.; Dang, D.; Doan, T.; Ghosal, M.; Khater, M.; McLean, K.; Porth, B.; Sowinski, Z.; Willets, C.; Xiong, C.; Yu, C.; Yum, S.; Giewont, K.; Green, W. M. J.

    2017-03-01

    Silicon photonics is rapidly becoming the key enabler for meeting the future data speed and volume required by the Internet of Things. A stable manufacturing process is needed to deliver cost and yield expectations to the technology marketplace. We present the key challenges and technical results from both 200mm and 300mm facilities for a silicon photonics fabrication process which includes monolithic integration with CMOS. This includes waveguide patterning, optical proximity correction for photonic devices, silicon thickness uniformity and thick material patterning for passive fiber to waveguide alignment. The device and process metrics show that the transfer of the silicon photonics process from 200mm to 300mm will provide a stable high volume manufacturing platform for silicon photonics designs.

  13. Silicone oil migration into the orbit.

    PubMed

    Ali Bautista, Sana; Wladis, Edward J; Farber, Martha; Falk, Naomi S; Phelps, Paul O

    2018-01-04

    To report a case in of intravitreal silicone oil migration into the inferior orbit. Silicone oil tamponade is commonly used in retinal detachment repair and extrusion into the orbital tissues is very rare. A 70-year-old male with a remote history of repair of a right ruptured globe and retinal detachment surgery presented with progressive right lower eyelid edema. There was a known history of intravitreal silicone oil instillation and removal. An elective right inferior orbitotomy with excisional biopsy was performed. Histopathology confirmed the presence of silicone oil intermixed with necrotic fat. The patient had excellent cosmetic and functional outcome. The presence of silicone oil within the orbital fat may be a result of increased intraocular pressure and extrusion through presumably water-tight sclerotomy sites.

  14. Smart integration of silicon nanowire arrays in all-silicon thermoelectric micro-nanogenerators

    NASA Astrophysics Data System (ADS)

    Fonseca, Luis; Santos, Jose-Domingo; Roncaglia, Alberto; Narducci, Dario; Calaza, Carlos; Salleras, Marc; Donmez, Inci; Tarancon, Albert; Morata, Alex; Gadea, Gerard; Belsito, Luca; Zulian, Laura

    2016-08-01

    Micro and nanotechnologies are called to play a key role in the fabrication of small and low cost sensors with excellent performance enabling new continuous monitoring scenarios and distributed intelligence paradigms (Internet of Things, Trillion Sensors). Harvesting devices providing energy autonomy to those large numbers of microsensors will be essential. In those scenarios where waste heat sources are present, thermoelectricity will be the obvious choice. However, miniaturization of state of the art thermoelectric modules is not easy with the current technologies used for their fabrication. Micro and nanotechnologies offer an interesting alternative considering that silicon in nanowire form is a material with a promising thermoelectric figure of merit. This paper presents two approaches for the integration of large numbers of silicon nanowires in a cost-effective and practical way using only micromachining and thin-film processes compatible with silicon technologies. Both approaches lead to automated physical and electrical integration of medium-high density stacked arrays of crystalline or polycrystalline silicon nanowires with arbitrary length (tens to hundreds microns) and diameters below 100 nm.

  15. Hot Electron Injection into Uniaxially Strained Silicon

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Soo

    In semiconductor spintronics, silicon attracts great attention due to the long electron spin lifetime. Silicon is also one of the most commonly used semiconductor in microelectronics industry. The spin relaxation process of diamond crystal structure such as silicon is dominant by Elliot-Yafet mechanism. Yafet shows that intravalley scattering process is dominant. The conduction electron spin lifetime measured by electron spin resonance measurement and electronic measurement using ballistic hot electron method well agrees with Yafet's theory. However, the recent theory predicts a strong contribution of intervalley scattering process such as f-process in silicon. The conduction band minimum is close the Brillouin zone edge, X point which causes strong spin mixing at the conduction band. A recent experiment of electric field-induced hot electron spin relaxation also shows the strong effect of f-process in silicon. In uniaxially strained silicon along crystal axis [100], the suppression of f-process is predicted which leads to enhance electron spin lifetime. By inducing a change in crystal structure due to uniaxial strain, the six fold degeneracy becomes two fold degeneracy, which is valley splitting. As the valley splitting increases, intervalley scattering is reduced. A recent theory predicts 4 times longer electron spin lifetime in 0.5% uniaxially strained silicon. In this thesis, we demonstrate ballistic hot electron injection into silicon under various uniaxial strain. Spin polarized hot electron injection under strain is experimentally one of the most challenging part to measure conduction electron spin lifetime in silicon. Hot electron injection adopts tunnel junction which is a thin oxide layer between two conducting materials. Tunnel barrier, which is an oxide layer, is only 4 ˜ 5 nm thick. Also, two conducting materials are only tens of nanometer. Therefore, under high pressure to apply 0.5% strain on silicon, thin films on silicon substrate can be easily

  16. Rough SERS substrate based on gold coated porous silicon layer prepared on the silicon backside surface

    NASA Astrophysics Data System (ADS)

    Dridi, H.; Haji, L.; Moadhen, A.

    2017-04-01

    We report in this paper a novel method to elaborate rough Surface Enhanced Raman Scattering (SERS) substrate. A single layer of porous silicon was formed on the silicon backside surface. Morphological characteristics of the porous silicon layer before and after gold deposition were influenced by the rough character (gold size). The reflectance measurements showed a dependence of the gold nano-grains size on the surface nature, through the Localized Surface Plasmon (LSP) band properties. SERS signal of Rhodamine 6G used as a model analyte, adsorbed on the rough porous silicon layer revealed a marked enhancement of its vibrational modes intensities.

  17. Silicon nanocluster-sensitized emission from erbium: The role of stress in the formation of silicon nanoclusters

    NASA Astrophysics Data System (ADS)

    Ahmad, I.; Temple, M. P.; Kallis, A.; Wojdak, M.; Oton, C. J.; Barbier, D.; Saleh, H.; Kenyon, A. J.; Loh, W. H.

    2008-12-01

    Erbium-doped silicon-rich silicon oxide films deposited by plasma enhanced chemical vapor deposition suffer from compressive stress as deposited, which converts to a large tensile stress on annealing due to the release of hydrogen. Although the cracking that results from this stress can be avoided by patterning the films into ridges, significant stress remains along the ridge axis. Measurements of erbium photoluminescence sensitized by silicon nanoclusters in stressed and relaxed films suggest an important role for internal film stresses in promoting the phase separation of excess silicon into nanoclusters, which has previously been thought of as a thermally driven process.

  18. Dry etch method for texturing silicon and device

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gershon, Talia S.; Haight, Richard A.; Kim, Jeehwan

    2017-07-25

    A method for texturing silicon includes loading a silicon wafer into a vacuum chamber, heating the silicon wafer and thermal cracking a gas to generate cracked sulfur species. The silicon wafer is exposed to the cracked sulfur species for a time duration in accordance with a texture characteristic needed for a surface of the silicon wafer.

  19. Choosing a Silicone Encapsulant for Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Velderrain, Michelle

    2011-12-01

    Growth in the solar industry has resulted in newer technologies, specifically concentrator photovoltaic (CPV) modules, to explore using new types of materials such as silicone encapsulants. CPV and LCPV module designs are to achieve the most efficient energy conversion possible however it is equally important to demonstrate long term reliability. Silicone is a material of interest due to its thermal stability and ability to absorb stresses incurred during thermal cycling. The refractive index of clear silicone adhesives is advantageous because it can be optimized using phenyl groups to match BK7 glass and other substrates to minimize light loss at the interfaces but it is relatively unknown how the optical properties change over time possibly yellowing in such a harsh environment. A 1.41 silicone encapsulant is compared to a 1.52 refractive index silicone. Optical Absorption (300 nm-1300 nm), Water Vapor Permeability, Moisture Absorption and effects of oxidation at elevated temperatures will be compared of these materials to aid the engineer in choosing a silicone for their CPV application. Non-phenyl containing 1.41 RI silicones have been used for several years for bonding solar arrays in the satellite industry. Phenyl groups on the siloxane polymer can change various properties of the silicone. Understanding how phenyl affects these properties allows the engineer to understand the benefits and risks when using a RI matching silicone to minimize light loss versus a non-phenyl containing silicone.

  20. Silicon Micromachined Microlens Array for THz Antennas

    NASA Technical Reports Server (NTRS)

    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

  1. Process for producing amorphous and crystalline silicon nitride

    DOEpatents

    Morgan, P.E.D.; Pugar, E.A.

    1985-11-12

    A process for producing amorphous or crystalline silicon nitride is disclosed which comprises reacting silicon disulfide ammonia gas at elevated temperature. In a preferred embodiment silicon disulfide in the form of whiskers'' or needles is heated at temperature ranging from about 900 C to about 1,200 C to produce silicon nitride which retains the whisker or needle morphological characteristics of the silicon disulfide. Silicon carbide, e.g. in the form of whiskers, also can be prepared by reacting substituted ammonia, e.g. methylamine, or a hydrocarbon containing active hydrogen-containing groups, such as ethylene, with silicon disulfide, at elevated temperature, e.g. 900 C. 6 figs.

  2. Process for producing amorphous and crystalline silicon nitride

    DOEpatents

    Morgan, Peter E. D.; Pugar, Eloise A.

    1985-01-01

    A process for producing amorphous or crystalline silicon nitride is disclosed which comprises reacting silicon disulfide ammonia gas at elevated temperature. In a preferred embodiment silicon disulfide in the form of "whiskers" or needles is heated at temperature ranging from about 900.degree. C. to about 1200.degree. C. to produce silicon nitride which retains the whisker or needle morphological characteristics of the silicon disulfide. Silicon carbide, e.g. in the form of whiskers, also can be prepared by reacting substituted ammonia, e.g. methylamine, or a hydrocarbon containing active hydrogen-containing groups, such as ethylene, with silicon disulfide, at elevated temperature, e.g. 900.degree. C.

  3. Femtosecond laser fabricating black silicon in alkaline solution

    NASA Astrophysics Data System (ADS)

    Meng, Jiao; Song, Haiying; Li, Xiaoli; Liu, Shibing

    2015-03-01

    An efficient approach for enhancing the surface antireflection is proposed, in which a black silicon is fabricated by a femtosecond laser in alkaline solution. In the experiment, 2 wt% NaOH solution is formulated at room temperature (22 ± 1 °C). Then, a polished silicon is scanned via femtosecond laser irradiation in 2 wt% NaOH solution. Jungle-like microstructures on the black silicon surface are characterized using an atomic force microscopy. The reflectance of the black silicon is measured at the wavelengths ranging from 400 to 750 nm. Compared to the polished silicon, the black silicon can significantly suppress the optical reflection throughout the visible region (<5 %). Meanwhile, we also investigated the factors of the black silicon, including the femtosecond laser pulse energy and the scanning speed. This method is simple and effective to acquire the black silicon, which probably has a large advantage in fast and cost-effective black silicon fabrication.

  4. Porous silicon-based direct hydrogen sulphide fuel cells.

    PubMed

    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.

  5. Porous silicon nanocrystals in a silica aerogel matrix

    PubMed Central

    2012-01-01

    Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation. PMID:22805684

  6. Porous silicon nanocrystals in a silica aerogel matrix.

    PubMed

    Amonkosolpan, Jamaree; Wolverson, Daniel; Goller, Bernhard; Polisski, Sergej; Kovalev, Dmitry; Rollings, Matthew; Grogan, Michael D W; Birks, Timothy A

    2012-07-17

    Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation.

  7. Photoluminescence of amorphous and crystalline silicon nanoclusters in silicon nitride and oxide superlattices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shuleiko, D. V., E-mail: shuleyko.dmitriy@physics.msu.ru; Zabotnov, S. V.; Zhigunov, D. M.

    2017-02-15

    The photoluminescence properties of silicon nitride and oxide superlattices fabricated by plasmaenhanced chemical vapor deposition are studied. In the structures annealed at a temperature of 1150°C, photoluminescence peaks at about 1.45 eV are recorded. The peaks are defined by exciton recombination in silicon nanocrystals formed upon annealing. Along with the 1.45-eV peaks, a number of peaks defined by recombination at defects at the interface between the nanocrystals and silicon-nitride matrix are detected. The structures annealed at 900°C exhibit a number of photoluminescence peaks in the range 1.3–2.0 eV. These peaks are defined by both the recombination at defects and excitonmore » recombination in amorphous silicon nanoclusters formed at an annealing temperature of 900°C. The observed features of all of the photoluminescence spectra are confirmed by the nature of the photoluminescence kinetics.« less

  8. Morphological Characterization of Silicone Hydrogels

    NASA Astrophysics Data System (ADS)

    Gido, Samuel

    2007-03-01

    Silicone hydrogel materials are used in the latest generation of extended wear soft contact lenses. To ensure comfort and eye health, these materials must simultaneously exhibit high oxygen permeability and high water permeability / hydrophilicity. The materials achieve these opposing requirements based on bicontinuous composite of nanoscale domains of oxygen permeable (silicones) and hydrophilic (water soluble polymer) materials. The microphase separated morphology of silicone hydrogel contact lens materials was imaged using field emission gun scanning transmission electron microscopy (FEGSTEM), and atomic force microscopy (AFM). Additional morphological information was provided by small angle X-ray scattering (SAXS). These results all indicate a nanophase separated structure of silicone rich (oxygen permeable) and carbon rich (water soluble polymer) domains separated on a length scale of about 10 nm.

  9. Process of preparing tritiated porous silicon

    DOEpatents

    Tam, S.W.

    1997-02-18

    A process of preparing tritiated porous silicon is described 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. 1 fig.

  10. Solar cells with gallium phosphide/silicon heterojunction

    NASA Astrophysics Data System (ADS)

    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.

  11. Silicon production in a fluidized bed reactor

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1986-01-01

    Part of the development effort of the JPL in-house technology involved in the Flat-Plate Solar Array (FSA) Project was the investigation of a low-cost process to produce semiconductor-grade silicon for terrestrial photovoltaic cell applications. The process selected was based on pyrolysis of silane in a fluidized-bed reactor (FBR). Following initial investigations involving 1- and 2-in. diameter reactors, a 6-in. diameter, engineering-scale FBR was constructed to establish reactor performance, mechanism of silicon deposition, product morphology, and product purity. The overall mass balance for all experiments indicates that more than 90% of the total silicon fed into the reactor is deposited on silicon seed particles and the remaining 10% becomes elutriated fines. Silicon production rates were demonstrated of 1.5 kg/h at 30% silane concentration and 3.5 kg/h at 80% silane concentration. The mechanism of silicon deposition is described by a six-path process: heterogeneous deposition, homogeneous decomposition, coalescence, coagulation, scavenging, and heterogeneous growth on fines. The bulk of the growth silicon layer appears to be made up of small diameter particles. This product morphology lends support to the concept of the scavenging of homogeneously nucleated silicon.

  12. Fabricating solar cells with silicon nanoparticles

    DOEpatents

    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.

  13. Method of forming crystalline silicon devices on glass

    DOEpatents

    McCarthy, Anthony M.

    1995-01-01

    A method for fabricating single-crystal silicon microelectronic components on a silicon substrate and transferring same to a glass substrate. This is achieved by utilizing conventional silicon processing techniques for fabricating components of electronic circuits and devices on bulk silicon, wherein a bulk silicon surface is prepared with epitaxial layers prior to the conventional processing. The silicon substrate is bonded to a glass substrate and the bulk silicon is removed leaving the components intact on the glass substrate surface. Subsequent standard processing completes the device and circuit manufacturing. This invention is useful in applications requiring a transparent or insulating substrate, particularly for display manufacturing. Other applications include sensors, actuators, optoelectronics, radiation hard electronics, and high temperature electronics.

  14. Tandem junction amorphous silicon solar cells

    DOEpatents

    Hanak, Joseph J.

    1981-01-01

    An amorphous silicon solar cell has an active body with two or a series of layers of hydrogenated amorphous silicon arranged in a tandem stacked configuration with one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon arranged in tandem configuration can have the same bandgap or differing bandgaps.

  15. Rapid fabrication of a silicon modification layer on silicon carbide substrate.

    PubMed

    Bai, Yang; Li, Longxiang; Xue, Donglin; Zhang, Xuejun

    2016-08-01

    We develop a kind of magnetorheological (MR) polishing fluid for the fabrication of a silicon modification layer on a silicon carbide substrate based on chemical theory and actual polishing requirements. The effect of abrasive concentration in MR polishing fluid on material removal rate and removal function shape is investigated. We conclude that material removal rate will increase and tends to peak value as the abrasive concentration increases to 0.3 vol. %, and the removal function profile will become steep, which is a disadvantage to surface frequency error removal at the same time. The removal function stability is also studied and the results show that the prepared MR polishing fluid can satisfy actual fabrication requirements. An aspheric reflective mirror of silicon carbide modified by silicon is well polished by combining magnetorheological finishing (MRF) using two types of MR polishing fluid and computer controlled optical surfacing (CCOS) processes. The surface accuracy root mean square (RMS) is improved from 0.087λ(λ=632.8  nm) initially to 0.020λ(λ=632.8  nm) in 5.5 h total and the tool marks resulting from MRF are negligible. The PSD analysis results also shows that the final surface is uniformly polished.

  16. Silicon Satellites: Picosats, Nanosats, and Microsats

    NASA Technical Reports Server (NTRS)

    Janson, Siegfried W.

    1995-01-01

    Silicon, the most abundant solid element in the Earth's lithosphere, is a useful material for spacecraft construction. Silicon is stronger than stainless steel, has a thermal conductivity about half that of aluminum, is transparent to much of the infrared radiation spectrum, and can form a stable oxide. These unique properties enable silicon to become most of the mass of a satellite, it can simultaneously function as structure, heat transfer system, radiation shield, optics, and semiconductor substrate. Semiconductor batch-fabrication techniques can produce low-power digital circuits, low-power analog circuits, silicon-based radio frequency circuits, and micro-electromechanical systems (MEMS) such as thrusters and acceleration sensors on silicon substrates. By exploiting these fabrication techniques, it is possible to produce highly-integrated satellites for a number of applications. This paper analyzes the limitations of silicon satellites due to size. Picosatellites (approximately 1 gram mass), nanosatellites (about 1 kg mass), and highly capable microsatellites (about 10 kg mass) can perform various missions with lifetimes of a few days to greater than a decade.

  17. Plasma Enabled Fabrication of Silicon Carbide Nanostructures

    NASA Astrophysics Data System (ADS)

    Fang, Jinghua; Levchenko, Igor; Aramesh, Morteza; Rider, Amanda E.; Prawer, Steven; Ostrikov, Kostya (Ken)

    Silicon carbide is one of the promising materials for the fabrication of various one- and two-dimensional nanostructures. In this chapter, we discuss experimental and theoretical studies of the plasma-enabled fabrication of silicon carbide quantum dots, nanowires, and nanorods. The discussed fabrication methods include plasma-assisted growth with and without anodic aluminium oxide membranes and with or without silane as a source of silicon. In the silane-free experiments, quartz was used as a source of silicon to synthesize the silicon carbide nanostructures in an environmentally friendly process. The mechanism of the formation of nanowires and nanorods is also discussed.

  18. Process Research On Polycrystalline Silicon Material (PROPSM)

    NASA Technical Reports Server (NTRS)

    Culik, J. S.; Wohlgemuth, J. H.

    1982-01-01

    Performance limiting mechanisms in polycrystalline silicon are investigated by fabricating a matrix of solar cells of various thicknesses from polycrystalline silicon wafers of several bulk resistivities. The analysis of the results for the entire matrix indicates that bulk recombination is the dominant factor limiting the short circuit current in large grain (greater than 1 to 2 mm diameter) polycrystalline silicon, the same mechanism that limits the short circuit current in single crystal silicon. An experiment to investigate the limiting mechanisms of open circuit voltage and fill factor for large grain polycrystalline silicon is designed. Two process sequences to fabricate small cells are investigated.

  19. A continuous silicon-coating facility

    NASA Technical Reports Server (NTRS)

    Butter, C.; Heaps, J. D.

    1979-01-01

    Automatic continuous silicon-coating facility is used to process 100 by 10 cm graphite-coated ceramic substrates for silicon solar cells. Process reduces contamination associated with conventional dip-coating processes, improving material service life.

  20. Silicon-Based Anode and Method for Manufacturing the Same

    NASA Technical Reports Server (NTRS)

    Yushin, Gleb Nikolayevich (Inventor); Zdyrko, Bogdan (Inventor); Magasinski, Alexandre (Inventor); Luzinov, Igor (Inventor)

    2017-01-01

    A silicon-based anode comprising silicon, a carbon coating that coats the surface of the silicon, a polyvinyl acid that binds to at least a portion of the silicon, and vinylene carbonate that seals the interface between the silicon and the polyvinyl acid. Because of its properties, polyvinyl acid binders offer improved anode stability, tunable properties, and many other attractive attributes for silicon-based anodes, which enable the anode to withstand silicon cycles of expansion and contraction during charging and discharging.

  1. Method of fabricating porous silicon carbide (SiC)

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  3. [Silicone in autoimmune diseases and cancer].

    PubMed

    Elejabeitia, J

    1999-01-01

    In 1992 the Food and Drug Administration (FDA) announced the restriction of silicone gel-filled breast implants until research protocol studies evaluate the relationship of silicone to connective tissue diseases, and the association of the silicone implants with breast carcinoma. Since them comprehensive epidemiologic studies have concluded that there is no connection between breast implants and the known connective tissue diseases or between the implants and breast carcinoma. During the same year, The American College of Rheumatology said that it have not been demonstrated the relationship between silicone gel breast implants and any systemic disease. Although this, the FDA restriction continues.

  4. Method of forming crystalline silicon devices on glass

    DOEpatents

    McCarthy, A.M.

    1995-03-21

    A method is disclosed for fabricating single-crystal silicon microelectronic components on a silicon substrate and transferring same to a glass substrate. This is achieved by utilizing conventional silicon processing techniques for fabricating components of electronic circuits and devices on bulk silicon, wherein a bulk silicon surface is prepared with epitaxial layers prior to the conventional processing. The silicon substrate is bonded to a glass substrate and the bulk silicon is removed leaving the components intact on the glass substrate surface. Subsequent standard processing completes the device and circuit manufacturing. This invention is useful in applications requiring a transparent or insulating substrate, particularly for display manufacturing. Other applications include sensors, actuators, optoelectronics, radiation hard electronics, and high temperature electronics. 7 figures.

  5. Silicon carbide thyristor

    NASA Technical Reports Server (NTRS)

    Edmond, John A. (Inventor); Palmour, John W. (Inventor)

    1996-01-01

    The SiC thyristor has a substrate, an anode, a drift region, a gate, and a cathode. The substrate, the anode, the drift region, the gate, and the cathode are each preferably formed of silicon carbide. The substrate is formed of silicon carbide having one conductivity type and the anode or the cathode, depending on the embodiment, is formed adjacent the substrate and has the same conductivity type as the substrate. A drift region of silicon carbide is formed adjacent the anode or cathode and has an opposite conductivity type as the anode or cathode. A gate is formed adjacent the drift region or the cathode, also depending on the embodiment, and has an opposite conductivity type as the drift region or the cathode. An anode or cathode, again depending on the embodiment, is formed adjacent the gate or drift region and has an opposite conductivity type than the gate.

  6. Fabrication of p-type porous silicon nanowire with oxidized silicon substrate through one-step MACE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Shaoyuan; Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093; Ma, Wenhui, E-mail: mwhsilicon@163.com

    2014-05-01

    In this paper, the simple pre-oxidization process is firstly used to treat the starting silicon wafer, and then MPSiNWs are successfully fabricated from the moderately doped wafer by one-step MACE technology in HF/AgNO{sub 3} system. The PL spectrum of MPSiNWs obtained from the oxidized silicon wafers show a large blue-shift, which can be attributed to the deep Q. C. effect induced by numerous mesoporous structures. The effects of HF and AgNO{sub 3} concentration on formation of SiNWs were carefully investigated. The results indicate that the higher HF concentration is favorable to the growth of SiNWs, and the density of SiNWsmore » is significantly reduced when Ag{sup +} ions concentrations are too high. The deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon surface were studied. According to the experimental results, a model was proposed to explain the formation mechanism of porous SiNWs by etching the oxidized starting silicon. - Graphical abstract: Schematic cross-sectional views of PSiNWs array formation by etching oxidized silicon wafer in HF/AgNO{sub 3} solution. (A) At the starting point; (B) during the etching process; and (C) after Ag dendrites remove. - Highlights: • Prior to etching, a simple pre-oxidation is firstly used to treat silicon substrate. • The medially doped p-type MPSiNWs are prepared by one-step MACE. • Deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon are studied. • A model is finally proposed to explain the formation mechanism of PSiNWs.« less

  7. Rapid Solid-State Metathesis Routes to Nanostructured Silicon-Germainum

    NASA Technical Reports Server (NTRS)

    Rodriguez, Marc (Inventor); Kaner, Richard B. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor)

    2014-01-01

    Methods for producing nanostructured silicon and silicon-germanium via solid state metathesis (SSM). The method of forming nanostructured silicon comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and an alkaline earth metal silicide into a homogeneous powder, and initating the reaction between the silicon tetraiodide (SiI4) with the alkaline earth metal silicide. The method of forming nanostructured silicon-germanium comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and a germanium based precursor into a homogeneous powder, and initiating the reaction between the silicon tetraiodide (SiI4) with the germanium based precursors.

  8. Silicon Micro- and Nanofabrication for Medicine

    PubMed Central

    Fine, Daniel; Goodall, Randy; Bansal, Shyam S.; Chiappini, Ciro; Hosali, Sharath; van de Ven, Anne L.; Srinivasan, Srimeenkashi; Liu, Xuewu; Godin, Biana; Brousseau, Louis; Yazdi, Iman K.; Fernandez-Moure, Joseph; Tasciotti, Ennio; Wu, Hung-Jen; Hu, Ye; Klemm, Steve; Ferrari, Mauro

    2013-01-01

    This manuscript constitutes a review of several innovative biomedical technologies fabricated using the precision and accuracy of silicon micro- and nanofabrication. The technologies to be reviewed are subcutaneous nanochannel drug delivery implants for the continuous tunable zero-order release of therapeutics, multi-stage logic embedded vectors for the targeted systemic distribution of both therapeutic and imaging contrast agents, silicon and porous silicon nanowires for investigating cellular interactions and processes as well as for molecular and drug delivery applications, porous silicon (pSi) as inclusions into biocomposites for tissue engineering, especially as it applies to bone repair and regrowth, and porous silica chips for proteomic profiling. In the case of the biocomposites, the specifically designed pSi inclusions not only add to the structural robustness, but can also promote tissue and bone regrowth, fight infection, and reduce pain by releasing stimulating factors and other therapeutic agents stored within their porous network. The common material thread throughout all of these constructs, silicon and its associated dielectrics (silicon dioxide, silicon nitride, etc.), can be precisely and accurately machined using the same scalable micro- and nanofabrication protocols that are ubiquitous within the semiconductor industry. These techniques lend themselves to the high throughput production of exquisitely defined and monodispersed nanoscale features that should eliminate architectural randomness as a source of experimental variation thereby potentially leading to more rapid clinical translation. PMID:23584841

  9. A "Sticky" Mucin-Inspired DNA-Polysaccharide Binder for Silicon and Silicon-Graphite Blended Anodes in Lithium-Ion Batteries.

    PubMed

    Kim, Sunjin; Jeong, You Kyeong; Wang, Younseon; Lee, Haeshin; Choi, Jang Wook

    2018-05-14

    New binder concepts have lately demonstrated improvements in the cycle life of high-capacity silicon anodes. Those binder designs adopt adhesive functional groups to enhance affinity with silicon particles and 3D network conformation to secure electrode integrity. However, homogeneous distribution of silicon particles in the presence of a substantial volumetric content of carbonaceous components (i.e., conductive agent, graphite, etc.) is still difficult to achieve while the binder maintains its desired 3D network. Inspired by mucin, the amphiphilic macromolecular lubricant, secreted on the hydrophobic surface of gastrointestine to interface aqueous serous fluid, here, a renatured DNA-alginate amphiphilic binder for silicon and silicon-graphite blended electrodes is reported. Mimicking mucin's structure comprised of a hydrophobic protein backbone and hydrophilic oligosaccharide branches, the renatured DNA-alginate binder offers amphiphilicity from both components, along with a 3D fractal network structure. The DNA-alginate binder facilitates homogeneous distribution of electrode components in the electrode as well as its enhanced adhesion onto a current collector, leading to improved cyclability in both silicon and silicon-graphite blended electrodes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Multifunctional silicon surfaces: reaction of dichlorocarbene generated from Seyferth reagent with hydrogen-terminated silicon (111) surfaces.

    PubMed

    Liu, Wenjun; Sharp, Ian D; Tilley, T Don

    2014-01-14

    Insertion of dichlorocarbene (:CCl2), generated by decomposition of the Seyferth reagent PhHgCCl2Br, into the Si-H bond of a tertiary silane to form a Si-CCl2H group is an efficient homogeneous, molecular transformation. A heterogeneous version of this reaction, between PhHgCCl2Br and a silicon (111) surface terminated by tertiary Si-H bonds, was studied using a combination of surface-sensitive infrared and X-ray photoelectron spectroscopies. The insertion of dichlorocarbene into surface Si-H bonds parallels the corresponding reaction of silanes in solution, to produce surface-bound dichloromethyl groups (Si-CCl2H) covering ∼25% of the silicon surface sites. A significant fraction of the remaining Si-H bonds on the surface was converted to Si-Cl/Br groups during the same reaction, with PhHgCCl2Br serving as a halogen atom source. The presence of two distinct environments for the chlorine atoms (Si-CCl2H and Si-Cl) and one type of bromine atom (Si-Br) was confirmed by Cl 2p, Br 3d, and C 1s X-ray photoelectron spectroscopy. The formation of reactive, halogen-terminated atop silicon sites was also verified by reaction with sodium azide or the Grignard reagent (CH3MgBr), to produce Si-N3 or Si-Me functionalities, respectively. Thus, reaction of a hydrogen-terminated silicon (111) surface with PhHgCCl2Br provides a facile route to multifunctional surfaces possessing both stable silicon-carbon and labile silicon-halogen sites, in a single pot synthesis. The reactive silicon-halogen groups can be utilized for subsequent transformations and, potentially, the construction of more complex organic-silicon hybrid systems.

  11. Heat exchanger-ingot casting/slicing process, phase 1: Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Schmid, F.; Khattak, C. P.

    1977-01-01

    A controlled growth, heat-flow and cool-down process is described that yielded silicon with a high degree of single crystallinity. Even when the seed melted out, very large grains formed. Solar cell samples made from cast material yielded conversion efficiency of over 9%. Representative characterizations of grown silicon demonstrated a dislocation density of less than 100/sq cm and a minority carrier diffusion length of 31 micron. The source of silicon carbide in silicon ingots was identified to be from graphite retainers in contact with silica crucibles. Higher growth rates were achieved with the use of a graphite plug at the bottom of the silica crucible.

  12. Solar silicon via the Dow Corning process

    NASA Technical Reports Server (NTRS)

    Hunt, L. P.; Dosaj, V. D.

    1979-01-01

    Technical feasibility for high volume production of solar cell-grade silicon is investigated. The process consists of producing silicon from pure raw materials via the carbothermic reduction of quartz. This silicon was then purified to solar grade by impurity segregation during Czochralski crystal growth. Commercially available raw materials were used to produce 100 kg quantities of silicon during 60 hour periods in a direct arc reactor. This silicon produced single crystalline ingot, during a second Czochralski pull, that was fabricated into solar cells having efficiencies ranging from 8.2 percent to greater than 14 percent. An energy analysis of the entire process indicated a 5 month payback time.

  13. Quantitative Analysis of Defects in Silicon. [to predict energy conversion efficiency of silicon samples for solar cells

    NASA Technical Reports Server (NTRS)

    Natesh, R.; Smith, J. M.; Qidwai, H. A.; Bruce, T.

    1979-01-01

    The evaluation and prediction of the conversion efficiency for a variety of silicon samples with differences in structural defects, such as grain boundaries, twin boundaries, precipitate particles, dislocations, etc. are discussed. Quantitative characterization of these structural defects, which were revealed by etching the surface of silicon samples, is performed by using an image analyzer. Due to different crystal growth and fabrication techniques the various types of silicon contain a variety of trace impurity elements and structural defects. The two most important criteria in evaluating the various silicon types for solar cell applications are cost and conversion efficiency.

  14. Flotation of Metallurgical Grade Silicon and Silicon Metal from Slag by Selective Hydrogen Fluoride-Assisted Flotation

    NASA Astrophysics Data System (ADS)

    Larsen, E.; Kleiv, R. A.

    2017-12-01

    Flotation experiments performed on metallurgical grade silicon have demonstrated that silicon (Si) can be floated in diluted solutions of hydrogen fluoride (HF) and a frother. The recovery was found to depend on HF conditioning time, frother type, and the concentration of both HF and frother. Although Brij 58 produced the highest recoveries of the frothers that was tested, good recoveries were also obtained for Flotanol C07. Chemical analyses showed that the flotation products were purer than the corresponding feed materials, and that most impurity elements were concentrated in the tailings. A case study on cleaning of slag containing 36 pct metallurgical silicon showed promising results concerning the recovery of silicon by flotation.

  15. Silicon material task. Part 3: Low-cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Roques, R. A.; Coldwell, D. M.

    1977-01-01

    The feasibility of a process for carbon reduction of low impurity silica in a plasma heat source was investigated to produce low-cost solar-grade silicon. Theoretical aspects of the reaction chemistry were studied with the aid of a computer program using iterative free energy minimization. These calculations indicate a threshold temperature exists at 2400 K below which no silicon is formed. The computer simulation technique of molecular dynamics was used to study the quenching of product species.

  16. Ocular silicon distribution and clearance following intravitreal injection of porous silicon microparticles

    PubMed Central

    Nieto, Alejandra; Hou, Huiyuan; Sailor, Michael J.; Freeman, William R.; Cheng, Lingyun

    2013-01-01

    Porous silicon (pSi) microparticles have been investigated for intravitreal drug delivery and demonstrated good biocompatibility. With the appropriate surface chemistry, pSi can reside in vitreous for months or longer. However, ocular distribution and clearance pathway of its degradation product, silicic acid, are not well understood. In the current study, rabbit ocular tissue was collected at different time point following fresh pSi (day 1, 5, 9, 16, and 21) or oxidized pSi (day 3, 7, 14, 21, and 35) intravitreal injection. In addition, dual-probe simultaneous microdialysis of aqueous and vitreous humor was performed following a bolus intravitreal injection of 0.25 mL silicic acid (150 μg/mL) and six consecutive microdialysates were collected every 20 min. Silicon was quantified from the samples using inductively coupled plasma-optical emission spectroscopy. The study showed that following the intravitreal injection of oxidized pSi, free silicon was consistently higher in the aqueous than in the retina (8.1 ± 6.5 vs. 3.4 ± 3.9 μg/mL, p = 0.0031). The area under the concentration-time curve (AUC) of the retina was only about 24% that of the aqueous. The mean residence time was 16 days for aqueous, 13 days for vitreous, 6 days for retina, and 18 days for plasma. Similarly, following intravitreal fresh pSi, free silicon was also found higher in aqueous than in retina (7 ± 4.7 vs. 3.4 ± 4.1 μg/mL, p = 0.014). The AUC for the retina was about 50% of the AUC for the aqueous. The microdialysis revealed the terminal half-life of free silicon in the aqueous was 30 min and 92 min in the vitreous; the AUC for aqueous accounted for 38% of the AUC for vitreous. Our studies indicate that aqueous humor is a significant pathway for silicon egress from the eye following intravitreal injection of pSi crystals. PMID:24036388

  17. Titanium dioxide/silicon hole-blocking selective contact to enable double-heterojunction crystalline silicon-based solar cell

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nagamatsu, Ken A., E-mail: knagamat@princeton.edu; Man, Gabriel; Jhaveri, Janam

    2015-03-23

    In this work, we use an electron-selective titanium dioxide (TiO{sub 2}) heterojunction contact to silicon to block minority carrier holes in the silicon from recombining at the cathode contact of a silicon-based photovoltaic device. We present four pieces of evidence demonstrating the beneficial effect of adding the TiO{sub 2} hole-blocking layer: reduced dark current, increased open circuit voltage (V{sub OC}), increased quantum efficiency at longer wavelengths, and increased stored minority carrier charge under forward bias. The importance of a low rate of recombination of minority carriers at the Si/TiO{sub 2} interface for effective blocking of minority carriers is quantitatively described.more » The anode is made of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) heterojunction to silicon which forms a hole selective contact, so that the entire device is made at a maximum temperature of 100 °C, with no doping gradients or junctions in the silicon. A low rate of recombination of minority carriers at the Si/TiO{sub 2} interface is crucial for effective blocking of minority carriers. Such a pair of complementary carrier-selective heterojunctions offers a path towards high-efficiency silicon solar cells using relatively simple and near-room temperature fabrication techniques.« less

  18. Electronic and Optical Properties of Novel Phases of Silicon and Silicon-Based Derivatives

    NASA Astrophysics Data System (ADS)

    Ong, Chin Shen; Choi, Sangkook; Louie, Steven

    2014-03-01

    The vast majority of solar cells in the market today are made from crystalline silicon in the diamond-cubic phase. Nonetheless, diamond-cubic Si has an intrinsic disadvantage: it has an indirect band gap with a large energy difference between the direct gap and the indirect gap. In this work, we perform a careful study of the electronic and optical properties of a newly discovered cubic-Si20 phase of Si that is found to sport a direct band gap. In addition, other silicon-based derivatives have also been discovered and found to be thermodynamically metastable. We carry out ab initio GW and GW-BSE calculations for the quasiparticle excitations and optical spectra, respectively, of these new phases of silicon and silicon-based derivatives. This work was supported by NSF grant No. DMR10-1006184 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided by DOE at Lawrence Berkeley National Laboratory's NERSC facility and the NSF through XSEDE resources at NICS.

  19. Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

    NASA Technical Reports Server (NTRS)

    Tanaka, Hidehiko

    1987-01-01

    A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

  20. Refining of metallurgical-grade silicon

    NASA Technical Reports Server (NTRS)

    Dietl, J.

    1986-01-01

    A basic requirement of large scale solar cell fabrication is to provide low cost base material. Unconventional refining of metallurical grade silicon represents one of the most promising ways of silicon meltstock processing. The refining concept is based on an optimized combination of metallurgical treatments. Commercially available crude silicon, in this sequence, requires a first pyrometallurgical step by slagging, or, alternatively, solvent extraction by aluminum. After grinding and leaching, high purity qualtiy is gained as an advanced stage of refinement. To reach solar grade quality a final pyrometallurgical step is needed: liquid-gas extraction.

  1. Process for Polycrystalline film silicon growth

    DOEpatents

    Wang, Tihu; Ciszek, Theodore F.

    2001-01-01

    A process for depositing polycrystalline silicon on substrates, including foreign substrates, occurs in a chamber at about atmospheric pressure, wherein a temperature gradient is formed, and both the atmospheric pressure and the temperature gradient are maintained throughout the process. Formation of a vapor barrier within the chamber that precludes exit of the constituent chemicals, which include silicon, iodine, silicon diiodide, and silicon tetraiodide. The deposition occurs beneath the vapor barrier. One embodiment of the process also includes the use of a blanketing gas that precludes the entrance of oxygen or other impurities. The process is capable of repetition without the need to reset the deposition zone conditions.

  2. System and method for liquid silicon containment

    DOEpatents

    Cliber, James A; Clark, Roger F; Stoddard, Nathan G; Von Dollen, Paul

    2013-05-28

    This invention relates to a system and a method for liquid silicon containment, such as during the casting of high purity silicon used in solar cells or solar modules. The containment apparatus includes a shielding member adapted to prevent breaching molten silicon from contacting structural elements or cooling elements of a casting device, and a volume adapted to hold a quantity of breaching molten silicon with the volume formed by a bottom and one or more sides.

  3. System and method for liquid silicon containment

    DOEpatents

    Cliber, James A; Clark, Roger F; Stoddard, Nathan G; Von Dollen, Paul

    2014-06-03

    This invention relates to a system and a method for liquid silicon containment, such as during the casting of high purity silicon used in solar cells or solar modules. The containment apparatus includes a shielding ember adapted to prevent breaching molten silicon from contacting structural elements or cooling elements of a casting device, and a volume adapted to hold a quantity of breaching molten silicon with the volume formed by a bottom and one or more sides.

  4. Electron Beam "Writes" Silicon On Sapphire

    NASA Technical Reports Server (NTRS)

    Heinemann, Klaus

    1988-01-01

    Method of growing silicon on sapphire substrate uses beam of electrons to aid growth of semiconductor material. Silicon forms as epitaxial film in precisely localized areas in micron-wide lines. Promising fabrication method for fast, densely-packed integrated circuits. Silicon deposited preferentially in contaminated substrate zones and in clean zone irradiated by electron beam. Electron beam, like surface contamination, appears to stimulate decomposition of silane atmosphere.

  5. Finishing Techniques for Silicon Nitride Bearings

    DTIC Science & Technology

    1976-03-01

    finishing procedures. Rolling contact fatigue lives of silicon nitride with selected smoother finishes tested at 800 ksi Hertz stress were an order...grinding. Rolling contact fatigue lives of silicon nitride with selected smoother finishes tested at 800 ksi Hertz stress were an order of magnitude...lives of silicon nitride with selected smoother finishes tested at 800 ksi Hertz stress were an order of magnitude longer than those

  6. Silicon micro-mold and method for fabrication

    DOEpatents

    Morales, Alfredo M.

    2005-01-11

    The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon micro-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

  7. Process Research on Polycrystalline Silicon Material (PROPSM)

    NASA Technical Reports Server (NTRS)

    Culik, J. S.

    1983-01-01

    The performance limiting mechanisms in large grain (greater than 1-2 mm in diameter) polycrystalline silicon was investigated by measuring the illuminated current voltage (I-V) characteristics of the minicell wafer set. The average short circuit current on different wafers is 3 to 14 percent lower than that of single crystal Czochralski silicon. The scatter was typically less than 3 percent. The average open circuit voltage is 20 to 60 mV less than that of single crystal silicon. The scatter in the open circuit voltage of most of the polycrystalline silicon wafers was 15 to 20 mV, although two wafers had significantly greater scatter than this value. The fill factor of both polycrystalline and single crystal silicon cells was typically in the range of 60 to 70 percent; however several polycrystalline silicon wafers have fill factor averages which are somewhat lower and have a significantly larger degree of scatter.

  8. Silicon Based Anodes for Li-Ion Batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Jiguang; Wang, Wei; Xiao, Jie

    2012-06-15

    Silicon is environmentally benign and ubiquitous. Because of its high specific capacity, it is considered one of the most promising candidates to replace the conventional graphite negative electrode used in today's Li ion batteries. Silicon has a theoretical specific capacity of nearly 4200 mAh/g (Li21Si5), which is 10 times larger than the specific capacity of graphite (LiC6, 372 mAh/g). However, the high capacity of silicon is associated with huge volume changes (more than 300 percent) when alloyed with lithium, which can cause severe cracking and pulverization of the electrode and lead to significant capacity loss. Significant scientific research has beenmore » conducted to circumvent the deterioration of silicon based anode materials during cycling. Various strategies, such as reduction of particle size, generation of active/inactive composites, fabrication of silicon based thin films, use of alternative binders, and the synthesis of 1-D silicon nanostructures have been implemented by a number of research groups. Fundamental mechanistic research has also been performed to better understand the electrochemical lithiation and delithiation process during cycling in terms of crystal structure, phase transitions, morphological changes, and reaction kinetics. Although efforts to date have not attained a commercially viable Si anode, further development is expected to produce anodes with three to five times the capacity of graphite. In this chapter, an overview of research on silicon based anodes used for lithium-ion battery applications will be presented. The overview covers electrochemical alloying of the silicon with lithium, mechanisms responsible for capacity fade, and methodologies adapted to overcome capacity degradation observed during cycling. The recent development of silicon nanowires and nanoparticles with significantly improved electrochemical performance will also be discussed relative to the mechanistic understanding. Finally, future directions on the

  9. Porous silicon technology for integrated microsystems

    NASA Astrophysics Data System (ADS)

    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

  10. Silicon (100)/SiO2 by XPS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh

    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 basemore » material for subsequent growth of templated carbon nanotubes.« less

  11. Roll up nanowire battery from silicon chips

    PubMed Central

    Vlad, Alexandru; Reddy, Arava Leela Mohana; Ajayan, Anakha; Singh, Neelam; Gohy, Jean-François; Melinte, Sorin; Ajayan, Pulickel M.

    2012-01-01

    Here we report an approach to roll out Li-ion battery components from silicon chips by a continuous and repeatable etch-infiltrate-peel cycle. Vertically aligned silicon nanowires etched from recycled silicon wafers are captured in a polymer matrix that operates as Li+ gel-electrolyte and electrode separator and peeled off to make multiple battery devices out of a single wafer. Porous, electrically interconnected copper nanoshells are conformally deposited around the silicon nanowires to stabilize the electrodes over extended cycles and provide efficient current collection. Using the above developed process we demonstrate an operational full cell 3.4 V lithium-polymer silicon nanowire (LIPOSIL) battery which is mechanically flexible and scalable to large dimensions. PMID:22949696

  12. Demonstration of slot-waveguide structures on silicon nitride / silicon oxide platform.

    PubMed

    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.

  13. Suppression of interfacial voids formation during silane (SiH4)-based silicon oxide bonding with a thin silicon nitride capping layer

    NASA Astrophysics Data System (ADS)

    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.

  14. Novel axially disubstituted non-aggregated silicon phthalocyanines.

    PubMed

    Bıyıklıoğlu, Zekeriya; Cakır, Dilek

    2012-12-01

    This paper describes the synthesis, spectroscopic characterization of a range of new axially-disubstituted silicon phthalocyanines with 2-[2-(dimethylamino)ethoxy] or 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy] groups as axial ligands. 2-[2-(Dimethylamino)ethoxy]ethanol 2, 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy]ethanol 4 are reacted with silicon phthalocyanine 1, to give an axially-disubstituted silicon phthalocyanines 3 and 5. Axially-disubstituted silicon phthalocyanine complexes were synthesized at the first time. Newly synthesized silicon phthalocyanines were characterized by UV-Vis, IR, (1)H NMR, (13)C NMR spectroscopy, ESI mass spectrometry. These new silicon(IV) phthalocyanines 3 and 5 showed excellent solubility in organic solvents such as CHCl(3), CH(2)Cl(2), acetone, DMF, DMSO, THF, EtOAc. The aggregation behavior of these compounds were investigated in different concentrations of DMSO. The effect of solvents on absorption spectra were studied in various organic solvents. The thermal stabilities of the silicon(IV) phthalocyanines 3 and 5 were determined by thermogravimetric analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Structure/permeability relationships of silicon-containing polyimides

    NASA Technical Reports Server (NTRS)

    Stern, S. A.; Vaidyanathan, R.; Pratt, J. R.

    1989-01-01

    The permeability to H2, O2, N2, CO2 and CH4 of three silicone-polyimide random copolymers and two polyimides containing silicon atoms in their backbone chains, was determined at 35.0 C and at pressures up to about 120 psig (approximately 8.2 atm). The copolymers contained different amounts of BPADA-m-PDA and amine-terminated poly (dimethyl siloxane) and also had different numbers of siloxane linkages in their silicone component. The polyimides containing silicon atoms (silicon-modified polyimides) were SiDA-4,4'-ODA and SiDA-p-PDA. The gas permeability and selectivity of the copolymers are more similar to those of their silicone component than of the polyimide component. By contrast, the permeability and selectivity of the silicon-modified polyimides are more similar to those of their parent polyimides, PMDA-4,4'-ODA and SiDA-p-PDA. The substitution of SiDA for the PMDA moiety in a polyimide appears to result in a significant increase in gas permeability, without a correspondingly large decrease in selectivity. The potential usefulness of the above polymers and copolymers as gas separation membranes is discussed.

  16. Solar cell with silicon oxynitride dielectric layer

    DOEpatents

    Shepherd, Michael; Smith, David D

    2015-04-28

    Solar cells with silicon oxynitride dielectric layers and methods of forming silicon oxynitride dielectric layers for solar cell fabrication are described. For example, an emitter region of a solar cell includes a portion of a substrate having a back surface opposite a light receiving surface. A silicon oxynitride (SiO.sub.xN.sub.y, 0silicon oxynitride dielectric layer.

  17. Diamond-silicon carbide composite and method

    DOEpatents

    Zhao, Yusheng [Los Alamos, NM

    2011-06-14

    Uniformly dense, diamond-silicon carbide composites having high hardness, high fracture toughness, and high thermal stability are prepared by consolidating a powder mixture of diamond and amorphous silicon. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPam.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness.

  18. Process for strengthening silicon based ceramics

    DOEpatents

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-01-01

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  19. Process for strengthening silicon based ceramics

    DOEpatents

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-04-06

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  20. Numerical Simulation Of Silicon-Ribbon Growth

    NASA Technical Reports Server (NTRS)

    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.

  1. Ion beam figuring of silicon aspheres

    NASA Astrophysics Data System (ADS)

    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.

  2. Silicon chemistry in interstellar clouds

    NASA Technical Reports Server (NTRS)

    Langer, William D.; Glassgold, A. E.

    1990-01-01

    A new model of interstellar silicon chemistry is presented that explains the lack of SiO detections in cold clouds and contains an exponential temperature dependence for the SiO abundance. A key aspect of the model is the sensitivity of SiO production by neutral silicon reactions to density and temperature, which arises from the dependence of the rate coefficients on the population of the excited fine-structure levels of the silicon atom. As part of the explanation of the lack of SiO detections at low temperatures and densities, the model also emphasizes the small efficiencies of the production routes and the correspondingly long times needed to reach equilibrium. Measurements of the abundance of SiO, in conjunction with theory, can provide information on the physical properties of interstellar clouds such as the abundance of oxygen bearing molecules and the depletion of interstellar silicon.

  3. Nanophotonic applications for silicon-on-insulator (SOI)

    NASA Astrophysics Data System (ADS)

    de la Houssaye, Paul R.; Russell, Stephen D.; Shimabukuro, Randy L.

    2004-07-01

    Silicon-on-insulator is a proven technology for very large scale integration of microelectronic devices. The technology also offers the potential for development of nanophotonic devices and the ability to interface such devices to the macroscopic world. This paper will report on fabrication techniques used to form nano-structured silicon wires on an insulating structure that is amenable to interfacing nanostructured sensors with high-performance microelectronic circuitry for practical implementation. Nanostructures formed on silicon-on-sapphire can also exploit the transparent substrate for novel device geometries. This research harnesses the unique properties of a high-quality single crystal film of silicon on sapphire and uses the film thickness as one of the confinement dimensions. Lateral arrays of silicon nanowires were fabricated in the thin (5 to 20 nm) silicon layer and studied. This technique offers simplified contact to individual wires and provides wire surfaces that are more readily accessible for controlled alteration and device designs.

  4. Quantitative Analysis of Defects in Silicon. Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low-cost Solar Array Project

    NASA Technical Reports Server (NTRS)

    Natesh, R.; Smith, J. M.; Qidwai, H. A.

    1979-01-01

    The various steps involved in the chemical polishing and etching of silicon samples are described. Data on twins, dislocation pits, and grain boundaries from thirty-one (31) silicon sample are also discussed. A brief review of the changes made to upgrade the image analysis system is included.

  5. Process for coating an object with silicon carbide

    NASA Technical Reports Server (NTRS)

    Levin, Harry (Inventor)

    1989-01-01

    A process for coating a carbon or graphite object with silicon carbide by contacting it with silicon liquid and vapor over various lengths of contact time. In the process, a stream of silicon-containing precursor material in gaseous phase below the decomposition temperature of said gas and a co-reactant, carrier or diluent gas such as hydrogen is passed through a hole within a high emissivity, thin, insulating septum into a reaction chamber above the melting point of silicon. The thin septum has one face below the decomposition temperature of the gas and an opposite face exposed to the reaction chamber. The precursor gas is decomposed directly to silicon in the reaction chamber. A stream of any decomposition gas and any unreacted precursor gas from said reaction chamber is removed. The object within the reaction chamber is then contacted with silicon, and recovered after it has been coated with silicon carbide.

  6. Tribological properties of sintered polycrystalline and single crystal silicon carbide

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.; Srinivasan, M.

    1982-01-01

    Tribological studies and X-ray photoelectron spectroscopy analyses were conducted with sintered polycrystalline and single crystal silicon carbide surfaces in sliding contact with iron at various temperatures to 1500 C in a vacuum of 30 nPa. The results indicate that there is a significant temperature influence on both the friction properties and the surface chemistry of silicon carbide. The main contaminants on the as received sintered polycrystalline silicon carbide surfaces are adsorbed carbon, oxygen, graphite, and silicon dioxide. The surface revealed a low coefficient of friction. This is due to the presence of the graphite on the surface. At temperatures of 400 to 600 C graphite and copious amount of silicon dioxide were observed on the polycrystalline silicon carbide surface in addition to silicon carbide. At 800 C, the amount of the silicon dioxide decreased rapidly and the silicon carbide type silicon and carbon peaks were at a maximum intensity in the XPS spectra. The coefficients of friction were high in the temperature range 400 to 800 C. Small amounts of carbon and oxygen contaminants were observed on the as received single crystal silicon carbide surface below 250 C. Silicon carbide type silicon and carbon peaks were seen on the silicon carbide in addition to very small amount of graphite and silicon dioxide at temperatures of 450 to 800 C.

  7. Material Analysis of Coated Siliconized Silicon Carbide (SiSiC) Honeycomb Structures for Thermochemical Hydrogen Production

    PubMed Central

    Neises-von Puttkamer, Martina; Simon, Heike; Schmücker, Martin; Roeb, Martin; Sattler, Christian; Pitz-Paal, Robert

    2013-01-01

    In the present work, thermochemical water splitting with siliconized silicon carbide (SiSiC) honeycombs coated with a zinc ferrite redox material was investigated. The small scale coated monoliths were tested in a laboratory test-rig and characterized by X-ray diffractometry (XRD) and Scanning Electron Microscopy (SEM) with corresponding micro analysis after testing in order to characterize the changes in morphology and composition. Comparison of several treated monoliths revealed the formation of various reaction products such as SiO2, zircon (ZrSiO4), iron silicide (FeSi) and hercynite (FeAl2O4) indicating the occurrence of various side reactions between the different phases of the coating as well as between the coating and the SiSiC substrate. The investigations showed that the ferrite is mainly reduced through reaction with silicon (Si), which is present in the SiSiC matrix, and silicon carbide (SiC). These results led to the formulation of a new redox mechanism for this system in which Zn-ferrite is reduced through Si forming silicon dioxide (SiO2) and through SiC forming SiO2 and carbon monoxide. A decline of hydrogen production within the first 20 cycles is suggested to be due to the growth of a silicon dioxide and zircon layer which acts as a diffusion barrier for the reacting specie. PMID:28809316

  8. Material Analysis of Coated Siliconized Silicon Carbide (SiSiC) Honeycomb Structures for Thermochemical Hydrogen Production.

    PubMed

    Neises-von Puttkamer, Martina; Simon, Heike; Schmücker, Martin; Roeb, Martin; Sattler, Christian; Pitz-Paal, Robert

    2013-01-31

    In the present work, thermochemical water splitting with siliconized silicon carbide (SiSiC) honeycombs coated with a zinc ferrite redox material was investigated. The small scale coated monoliths were tested in a laboratory test-rig and characterized by X-ray diffractometry (XRD) and Scanning Electron Microscopy (SEM) with corresponding micro analysis after testing in order to characterize the changes in morphology and composition. Comparison of several treated monoliths revealed the formation of various reaction products such as SiO₂, zircon (ZrSiO₄), iron silicide (FeSi) and hercynite (FeAl₂O₄) indicating the occurrence of various side reactions between the different phases of the coating as well as between the coating and the SiSiC substrate. The investigations showed that the ferrite is mainly reduced through reaction with silicon (Si), which is present in the SiSiC matrix, and silicon carbide (SiC). These results led to the formulation of a new redox mechanism for this system in which Zn-ferrite is reduced through Si forming silicon dioxide (SiO₂) and through SiC forming SiO₂ and carbon monoxide. A decline of hydrogen production within the first 20 cycles is suggested to be due to the growth of a silicon dioxide and zircon layer which acts as a diffusion barrier for the reacting specie.

  9. Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project. Third quarterly report, September 20, 1976--December 19, 1976

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Holden, S.C.

    1976-12-27

    The stability of tensioned blades used in multiblade sawing does not seem to be the limitation in cutting with thin blades. So far, 0.010 cm thick blades have been totally unsuccessful. Recently, 0.015 cm blades have proven successful in wafering, offering an 0.005 cm reduction in the silicon used per slice. The failure of thin blades is characterized as a possible result of blade misalignment or from the inherent uncontrollability of the loose abrasive multiblade process. Corrective procedures will be employed in the assembly of packages to eliminate one type of blade misalignment. Two ingots were sliced with the samemore » batch of standard silicon carbide abrasive slurry to determine the useful lifetime of this expendable material. After 250 slices, the cutting efficiency had not degraded. Further tests will be continued to establish the maximum lifetime of both silicon carbide and boron carbide abrasive. Electron microscopy will be employed to evaluate the wear of abrasive particles in the failure of abrasive slurry. The surface damage of silicon wafers has been characterized as predominantly subsurface fracture. Damage with No. 600 SiC is between 10 and 15 microns into the wafer surface. This agrees well with previous investigations of damage from silicon carbide abrasive papers.« less

  10. Apparatus for obtaining silicon from fluosilicic acid

    DOEpatents

    Sanjurjo, Angel

    1986-05-20

    Apparatus for producing low cost, high purity solar grade silicon ingots in single crystal or quasi single crystal ingot form in a substantially continuous operation in a two stage reactor starting with sodium fluosilicate and a metal more electropositive than silicon (preferably sodium) in separate compartments having easy vapor transport therebetween and thermally decomposing the sodium fluosilicate to cause formation of substantially pure silicon and a metal fluoride which may be continuously separated in the melt and silicon may be directly and continuously cast from the melt.

  11. Micro benchtop optics by bulk silicon micromachining

    DOEpatents

    Lee, Abraham P.; Pocha, Michael D.; McConaghy, Charles F.; Deri, Robert J.

    2000-01-01

    Micromachining of bulk silicon utilizing the parallel etching characteristics of bulk silicon and integrating the parallel etch planes of silicon with silicon wafer bonding and impurity doping, enables the fabrication of on-chip optics with in situ aligned etched grooves for optical fibers, micro-lenses, photodiodes, and laser diodes. Other optical components that can be microfabricated and integrated include semi-transparent beam splitters, micro-optical scanners, pinholes, optical gratings, micro-optical filters, etc. Micromachining of bulk silicon utilizing the parallel etching characteristics thereof can be utilized to develop miniaturization of bio-instrumentation such as wavelength monitoring by fluorescence spectrometers, and other miniaturized optical systems such as Fabry-Perot interferometry for filtering of wavelengths, tunable cavity lasers, micro-holography modules, and wavelength splitters for optical communication systems.

  12. Silicon solar cell process development, fabrication and analysis

    NASA Technical Reports Server (NTRS)

    Minahan, J. A.

    1981-01-01

    The fabrication of solar cells from several unconventional silicon materials is described, and cell performance measured and analyzed. Unconventional materials evaluated are edge defined film fed grown (EFG), heat exchanger method (HEM), dendritic web grown, and continuous CZ silicons. Resistivity, current voltage, and spectral sensitivity of the cells were measured. Current voltage was measured under AM0 and AM1 conditions. Maximum conversion efficiencies of cells fabricated from these and other unconventional silicons were compared and test results analyzed. The HEM and continuous CZ silicon were found to be superior to silicon materials considered previously.

  13. Converting a carbon preform object to a silicon carbide object

    NASA Technical Reports Server (NTRS)

    Levin, Harry (Inventor)

    1990-01-01

    A process for converting in depth a carbon or graphite preform object to a silicon carbide object, silicon carbide/silicon object, silicon carbide/carbon-core object, or a silicon carbide/silicon/carbon-core object, by contacting it with silicon liquid and vapor over various lengths of contact time in a reaction chamber. In the process, a stream comprised of a silicon-containing precursor material in gaseous phase below the decomposition temperature of said gas and a coreactant, carrier or diluent gas such as hydrogen is passed through a hole within a high emissivity, thin, insulating septum into the reaction chamber above the melting point of silicon. The thin septum has one face below the decomposition temperature of the gas and an opposite face exposed to the reaction chamber. Thus, the precursor gas is decomposed directly to silicon in the reaction chamber. Any stream of decomposition gas and any unreacted precursor gas from the reaction chamber is removed. A carbon or graphite preform object placed in the reaction chamber is contacted with the silicon. The carbon or graphite preform object is recovered from the reactor chamber after it has been converted to a desired silicon carbide, silicon and carbon composition.

  14. Silicon microengineering for accelerometers

    NASA Astrophysics Data System (ADS)

    Satchell, D. W.

    Silicon microengineering enables the excellent mechanical properties of silicon to be combined with electronic ones to produce accelerometers of good performance, small size and low cost. The design and fabrication of two types of analogue accelerometer, using this technique, are described. One employs implanted strain gauges to give a dc output, while the other has a strain-sensitive resonant structure which gives a varying frequency signal.

  15. SPS silicon reference system

    NASA Technical Reports Server (NTRS)

    Woodcock, G. R.

    1980-01-01

    The design analysis of a silicon power conversion system for the solar power satellite (SPS) is summarized. The solar array, consisting of glass encapsulated 50 micrometer silicon solar cells, is described. The general scheme for power distribution to the array/antenna interface is described. Degradation by proton irradiation is considered. The interface between the solar array and the klystron equipped power transmitter is described.

  16. Slicing of silicon into sheet material: Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Holden, S. C.

    1976-01-01

    Multiblade slurry sawing is used to slice 10 cm diameter silicon ingots into wafers 0.024 cm thick using 0.050 cm of silicon per slice (0.026 cm kerf loss). Total slicing time is less than twenty hours, and 143 slices are produced simultaneously. Productivity (slice area per hour per blade) is shown as a function or blade load and thickness, and abrasive size. Finer abrasive slurries cause a reduction in slice productivity, and thin blades cause a reduction of wafer accuracy. Sawing induced surface damage is found to extend 18 microns into the wafer.

  17. Buried Porous Silicon-Germanium Layers in Monocrystalline Silicon Lattices

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Monocrystalline semiconductor lattices with a buried porous semiconductor layer having different chemical composition is discussed and monocrystalline semiconductor superlattices with a buried porous semiconductor layers having different chemical composition than that of its monocrystalline semiconductor superlattice are discussed. Lattices of alternating layers of monocrystalline silicon and porous silicon-germanium have been produced. These single crystal lattices have been fabricated by epitaxial growth of Si and Si-Ge layers followed by patterning into mesa structures. The mesa structures are strain etched resulting in porosification of the Si-Ge layers with a minor amount of porosification of the monocrystalline Si layers. Thicker Si-Ge layers produced in a similar manner emitted visible light at room temperature.

  18. Silicon heterojunction solar cells with novel fluorinated n-type nanocrystalline silicon oxide emitters on p-type crystalline silicon

    NASA Astrophysics Data System (ADS)

    Dhar, Sukanta; Mandal, Sourav; Das, Gourab; Mukhopadhyay, Sumita; Pratim Ray, Partha; Banerjee, Chandan; Barua, Asok Kumar

    2015-08-01

    A novel fluorinated phosphorus doped silicon oxide based nanocrystalline material have been used to prepare heterojunction solar cells on flat p-type crystalline silicon (c-Si) Czochralski (CZ) wafers. The n-type nc-SiO:F:H material were deposited by radio frequency plasma enhanced chemical vapor deposition. Deposited films were characterized in detail by using atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM), Raman, fourier transform infrared spectroscopy (FTIR) and optoelectronics properties have been studied using temperature dependent conductivity measurement, Ellipsometry, UV-vis spectrum analysis etc. It is observed that the cell fabricated with fluorinated silicon oxide emitter showing higher initial efficiency (η = 15.64%, Jsc = 32.10 mA/cm2, Voc = 0.630 V, FF = 0.77) for 1 cm2 cell area compare to conventional n-a-Si:H emitter (14.73%) on flat c-Si wafer. These results indicate that n type nc-SiO:F:H material is a promising candidate for heterojunction solar cell on p-type crystalline wafers. The high Jsc value is associated with excellent quantum efficiencies at short wavelengths (<500 nm).

  19. Electrically Conductive and Optically Active Porous Silicon Nanowires

    PubMed Central

    Qu, Yongquan; Liao, Lei; Li, Yujing; Zhang, Hua; Huang, Yu; Duan, Xiangfeng

    2009-01-01

    We report the synthesis of vertical silicon nanowire array through a two-step metal-assisted chemical etching of highly doped n-type silicon (100) wafers in a solution of hydrofluoric acid and hydrogen peroxide. The morphology of the as-grown silicon nanowires is tunable from solid nonporous nanowires, nonporous/nanoporous core/shell nanowires, and entirely nanoporous nanowires by controlling the hydrogen peroxide concentration in the etching solution. The porous silicon nanowires retain the single crystalline structure and crystallographic orientation of the starting silicon wafer, and are electrically conductive and optically active with visible photoluminescence. The combination of electronic and optical properties in the porous silicon nanowires may provide a platform for the novel optoelectronic devices for energy harvesting, conversion and biosensing. PMID:19807130

  20. Low cost solar array project 1: Silicon material

    NASA Technical Reports Server (NTRS)

    Jewett, D. N.; Bates, H. E.; Hill, D. M.

    1980-01-01

    The low cost production of silicon by deposition of silicon from a hydrogen/chlorosilane mixture is described. Reactor design, reaction vessel support systems (physical support, power control and heaters, and temperature monitoring systems) and operation of the system are reviewed. Testing of four silicon deposition reactors is described, and test data and consequently derived data are given. An 18% conversion of trichlorosilane to silicon was achieved, but average conversion rates were lower than predicted due to incomplete removal of byproduct gases for recycling and silicon oxide/silicon polymer plugging of the gas outlet. Increasing the number of baffles inside the reaction vessel improved the conversion rate. Plans for further design and process improvements to correct the problems encountered are outlined.

  1. High surface area silicon materials: fundamentals and new technology.

    PubMed

    Buriak, Jillian M

    2006-01-15

    Crystalline silicon forms the basis of just about all computing technologies on the planet, in the form of microelectronics. An enormous amount of research infrastructure and knowledge has been developed over the past half-century to construct complex functional microelectronic structures in silicon. As a result, it is highly probable that silicon will remain central to computing and related technologies as a platform for integration of, for instance, molecular electronics, sensing elements and micro- and nanoelectromechanical systems. Porous nanocrystalline silicon is a fascinating variant of the same single crystal silicon wafers used to make computer chips. Its synthesis, a straightforward electrochemical, chemical or photochemical etch, is compatible with existing silicon-based fabrication techniques. Porous silicon literally adds an entirely new dimension to the realm of silicon-based technologies as it has a complex, three-dimensional architecture made up of silicon nanoparticles, nanowires, and channel structures. The intrinsic material is photoluminescent at room temperature in the visible region due to quantum confinement effects, and thus provides an optical element to electronic applications. Our group has been developing new organic surface reactions on porous and nanocrystalline silicon to tailor it for a myriad of applications, including molecular electronics and sensing. Integration of organic and biological molecules with porous silicon is critical to harness the properties of this material. The construction and use of complex, hierarchical molecular synthetic strategies on porous silicon will be described.

  2. Neuromorphic Silicon Neuron Circuits

    PubMed Central

    Indiveri, Giacomo; Linares-Barranco, Bernabé; Hamilton, Tara Julia; van Schaik, André; Etienne-Cummings, Ralph; Delbruck, Tobi; Liu, Shih-Chii; Dudek, Piotr; Häfliger, Philipp; Renaud, Sylvie; Schemmel, Johannes; Cauwenberghs, Gert; Arthur, John; Hynna, Kai; Folowosele, Fopefolu; Saighi, Sylvain; Serrano-Gotarredona, Teresa; Wijekoon, Jayawan; Wang, Yingxue; Boahen, Kwabena

    2011-01-01

    Hardware implementations of spiking neurons can be extremely useful for a large variety of applications, ranging from high-speed modeling of large-scale neural systems to real-time behaving systems, to bidirectional brain–machine interfaces. The specific circuit solutions used to implement silicon neurons depend on the application requirements. In this paper we describe the most common building blocks and techniques used to implement these circuits, and present an overview of a wide range of neuromorphic silicon neurons, which implement different computational models, ranging from biophysically realistic and conductance-based Hodgkin–Huxley models to bi-dimensional generalized adaptive integrate and fire models. We compare the different design methodologies used for each silicon neuron design described, and demonstrate their features with experimental results, measured from a wide range of fabricated VLSI chips. PMID:21747754

  3. Efficient Second-Harmonic Generation in Nanocrystalline Silicon Nanoparticles.

    PubMed

    Makarov, Sergey V; Petrov, Mihail I; Zywietz, Urs; Milichko, Valentin; Zuev, Dmitry; Lopanitsyna, Natalia; Kuksin, Alexey; Mukhin, Ivan; Zograf, George; Ubyivovk, Evgeniy; Smirnova, Daria A; Starikov, Sergey; Chichkov, Boris N; Kivshar, Yuri S

    2017-05-10

    Recent trends to employ high-index dielectric particles in nanophotonics are motivated by their reduced dissipative losses and large resonant enhancement of nonlinear effects at the nanoscale. Because silicon is a centrosymmetric material, the studies of nonlinear optical properties of silicon nanoparticles have been targeting primarily the third-harmonic generation effects. Here we demonstrate, both experimentally and theoretically, that resonantly excited nanocrystalline silicon nanoparticles fabricated by an optimized laser printing technique can exhibit strong second-harmonic generation (SHG) effects. We attribute an unexpectedly high yield of the nonlinear conversion to a nanocrystalline structure of nanoparticles supporting the Mie resonances. The demonstrated efficient SHG at green light from a single silicon nanoparticle is 2 orders of magnitude higher than that from unstructured silicon films. This efficiency is significantly higher than that of many plasmonic nanostructures and small silicon nanoparticles in the visible range, and it can be useful for a design of nonlinear nanoantennas and silicon-based integrated light sources.

  4. Breast Implants: Saline vs. Silicone

    MedlinePlus

    ... sticky fluid that closely mimics the feel of human fat. Most women feel that silicone breast implants look and feel more like natural breast tissue. Silicone breast implants are available to women 22 and older for breast augmentation and to women of any age for breast ...

  5. Compensated amorphous silicon solar cell

    DOEpatents

    Carlson, David E.

    1980-01-01

    An amorphous silicon solar cell incorporates a region of intrinsic hydrogenated amorphous silicon fabricated by a glow discharge wherein said intrinsic region is compensated by P-type dopants in an amount sufficient to reduce the space charge density of said region under illumination to about zero.

  6. Rectangular-cladding silicon slot waveguide with improved nonlinear performance

    NASA Astrophysics Data System (ADS)

    Huang, Zengzhi; Huang, Qingzhong; Wang, Yi; Xia, Jinsong

    2018-04-01

    Silicon slot waveguides have great potential in hybrid silicon integration to realize nonlinear optical applications. We propose a rectangular-cladding hybrid silicon slot waveguide. Simulation result shows that, with a rectangular-cladding, the slot waveguide can be formed by narrower silicon strips, so the two-photon absorption (TPA) loss in silicon is decreased. When the cladding material is a nonlinear polymer, the calculated TPA figure of merit (FOMTPA) is 4.4, close to the value of bulk nonlinear polymer of 5.0. This value confirms the good nonlinear performance of rectangular-cladding silicon slot waveguides.

  7. Microelectromechanical pump utilizing porous silicon

    DOEpatents

    Lantz, Jeffrey W [Albuquerque, NM; Stalford, Harold L [Norman, OK

    2011-07-19

    A microelectromechanical (MEM) pump is disclosed which includes a porous silicon region sandwiched between an inlet chamber and an outlet chamber. The porous silicon region is formed in a silicon substrate and contains a number of pores extending between the inlet and outlet chambers, with each pore having a cross-section dimension about equal to or smaller than a mean free path of a gas being pumped. A thermal gradient is provided along the length of each pore by a heat source which can be an electrical resistance heater or an integrated circuit (IC). A channel can be formed through the silicon substrate so that inlet and outlet ports can be formed on the same side of the substrate, or so that multiple MEM pumps can be connected in series to form a multi-stage MEM pump. The MEM pump has applications for use in gas-phase MEM chemical analysis systems, and can also be used for passive cooling of ICs.

  8. Formation of iron disilicide on amorphous silicon

    NASA Astrophysics Data System (ADS)

    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 <111> 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.

  9. Production of high specific activity silicon-32

    DOEpatents

    Phillips, Dennis R.; Brzezinski, Mark A.

    1994-01-01

    A process for preparation of silicon-32 is provide and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  10. Ocular silicon distribution and clearance following intravitreal injection of porous silicon microparticles.

    PubMed

    Nieto, Alejandra; Hou, Huiyuan; Sailor, Michael J; Freeman, William R; Cheng, Lingyun

    2013-11-01

    Porous silicon (pSi) microparticles have been investigated for intravitreal drug delivery and demonstrated good biocompatibility. With the appropriate surface chemistry, pSi can reside in vitreous for months or longer. However, ocular distribution and clearance pathway of its degradation product, silicic acid, are not well understood. In the current study, rabbit ocular tissue was collected at different time point following fresh pSi (day 1, 5, 9, 16, and 21) or oxidized pSi (day 3, 7, 14, 21, and 35) intravitreal injection. In addition, dual-probe simultaneous microdialysis of aqueous and vitreous humor was performed following a bolus intravitreal injection of 0.25 mL silicic acid (150 μg/mL) and six consecutive microdialysates were collected every 20 min. Silicon was quantified from the samples using inductively coupled plasma-optical emission spectroscopy. The study showed that following the intravitreal injection of oxidized pSi, free silicon was consistently higher in the aqueous than in the retina (8.1 ± 6.5 vs. 3.4 ± 3.9 μg/mL, p = 0.0031). The area under the concentration-time curve (AUC) of the retina was only about 24% that of the aqueous. The mean residence time was 16 days for aqueous, 13 days for vitreous, 6 days for retina, and 18 days for plasma. Similarly, following intravitreal fresh pSi, free silicon was also found higher in aqueous than in retina (7 ± 4.7 vs. 3.4 ± 4.1 μg/mL, p = 0.014). The AUC for the retina was about 50% of the AUC for the aqueous. The microdialysis revealed the terminal half-life of free silicon in the aqueous was 30 min and 92 min in the vitreous; the AUC for aqueous accounted for 38% of the AUC for vitreous. Our studies indicate that aqueous humor is a significant pathway for silicon egress from the eye following intravitreal injection of pSi crystals. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Lithium insertion in carbonaceous materials containing silicon

    NASA Astrophysics Data System (ADS)

    Wilson, Alfred Macdonald

    Three different series of silicon-containing carbonaceous materials were synthesized for use as anodes in lithium ion cells. Disordered (or pregraphitic) carbons containing nanodispersed silicon were prepared by the chemical vapour deposition (CVD) of various chlorosilanes (SiClsb4, (CHsb3)sb2Clsb2Si, and (CHsb3)sb3ClSi) with benzene in two different apparatuses. Silicon oxycarbide glasses were synthesized by the pyrolysis of over 50 silicon-containing polymers at various temperatures, although the principal materials in the study were prepared at 1000sp°C. Finally, materials which we believe to be similar to disordered carbons containing nanodispersed silicon were prepared by the pyrolysis of various blends of pitches with polysilanes. Powder X-ray diffraction was used to learn about the structure of all the materials made. Thermal gravimetric analysis was used to determine the silicon content in the CVD materials and, when coupled to a residual gas analyzer, to study the decomposition process of the polymers. Near edge X-ray absorption spectroscopy measurements of the silicon L- and K-edges of CVD materials and the silicon K-edges of silicon oxycarbides were used to learn about local chemical environments of the silicon atoms. Lithium metal electrochemical test cells of the silicon-containing CVD materials showed larger capacities (up to 500 mAh/g) than pure carbons prepared in the same way (˜300 mAh/g). The additional capacity was observed to be centered near 0.4 V on charge, the average voltage observed for the removal of lithium from a silicon-lithium alloy. Chemical analysis showed that the stoichiometries of materials made by polymer pyrolysis were distributed over a well-defined region in the Si-O-C Gibbs phase diagram. An interesting series of materials is found near the line in the Si-O-C Gibbs triangle connecting carbon to SiOsb{1.3}. Lithium metal electrochemical test cells made using all the silicon oxycarbides synthesized showed that a stoichiometry

  12. Silicon carbide reinforced silicon carbide composite

    NASA Technical Reports Server (NTRS)

    Lau, Sai-Kwing (Inventor); Calandra, Salvatore J. (Inventor); Ohnsorg, Roger W. (Inventor)

    2001-01-01

    This invention relates to a process comprising the steps of: a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C., b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbon c) providing a cover mix comprising: i) an alloy comprising a metallic infiltrant and the coating element, and ii) a resin, d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body, e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, and f) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.

  13. Axillary silicone lymphadenopathy secondary to augmentation mammaplasty

    PubMed Central

    Dragoumis, Dimitrios M.; Assimaki, Anthoula S.; Vrizas, Triantafyllos I.; Tsiftsoglou, Aris P.

    2010-01-01

    We report a case involving a 45-year-old woman, who presented with an axillary mass 10 years after bilateral cosmetic augmentation mammaplasty. A lump was detected in the left axilla, and subsequent mammography and magnetic resonance imaging demonstrated intracapsular rupture of the left breast prosthesis. An excisional biopsy of the left axillary lesion and replacement of the ruptured implant was performed. Histological analysis showed that the axillary lump was lymph nodes containing large amounts of silicone. Silicone lymphadenopathy is an obscure complication of procedures involving the use of silicone. It is thought to occur following the transit of silicone droplets from breast implants to lymph nodes by macrophages and should always be considered as a differential diagnosis in patients in whom silicone prostheses are present. PMID:21217983

  14. Silicon nanostructures for cancer diagnosis and therapy.

    PubMed

    Peng, Fei; Cao, Zhaohui; Ji, Xiaoyuan; Chu, Binbin; Su, Yuanyuan; He, Yao

    2015-01-01

    The emergence of nanotechnology suggests new and exciting opportunities for early diagnosis and therapy of cancer. During the recent years, silicon-based nanomaterials featuring unique properties have received great attention, showing high promise for myriad biological and biomedical applications. In this review, we will particularly summarize latest representative achievements on the development of silicon nanostructures as a powerful platform for cancer early diagnosis and therapy. First, we introduce the silicon nanomaterial-based biosensors for detecting cancer markers (e.g., proteins, tumor-suppressor genes and telomerase activity, among others) with high sensitivity and selectivity under molecular level. Then, we summarize in vitro and in vivo applications of silicon nanostructures as efficient nanoagents for cancer therapy. Finally, we discuss the future perspective of silicon nanostructures for cancer diagnosis and therapy.

  15. Method of producing buried porous silicon-geramanium layers in monocrystalline silicon lattices

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    Lattices of alternating layers of monocrystalline silicon and porous silicon-germanium have been produced. These single crystal lattices have been fabricated by epitaxial growth of Si and Si--Ge layers followed by patterning into mesa structures. The mesa structures are stain etched resulting in porosification of the Si--Ge layers with a minor amount of porosification of the monocrystalline Si layers. Thicker Si--Ge layers produced in a similar manner emitted visible light at room temperature.

  16. The effect of silicone-gel on the immune response.

    PubMed

    Naim, J O; Lanzafame, R J; van Oss, C J

    1995-01-01

    Silicone materials have been used in medical applications for at least 30 years. Despite this long history of use the question whether silicones can mediate an immunological reaction that may be detrimental to the host remains unanswered. Most studies on the biocompatability of silicones conclude that silicones are chemically stable compounds, which however are often capable of eliciting a benign chronic inflammatory response. Recently, our laboratory has conducted a series of animal experiments aimed at determining the immunological adjuvancy potential of silicone-gel taken from commercial breast implants. Our previous studies have indicated that silicone-gel is a potent humoral (antibody) adjuvant. Our present studies have found that silicone-gel is capable of eliciting auto-antibodies to rat thyroglobulin and bovine collagen II. However this immune response did not produce any histological evidence of thyroiditis or arthritis. Theories to explain why silicone-gel behaves as an adjuvant are discussed along with discussion of the hypothesis on the desirability of replacing silicone-gel with a more hydrophilic material in bioimplants.

  17. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  18. Silicon Hot-Electron Bolometers

    NASA Technical Reports Server (NTRS)

    Stevenson, Thomas R.; Hsieh, Wen-Ting; Mitchell, Robert R.; Isenberg, Hal D.; Stahle, Carl M.; Cao, Nga T.; Schneider, Gideon; Travers, Douglas E.; Moseley, S. Harvey; Wollack, Edward J.

    2004-01-01

    We discuss a new type of direct detector, a silicon hot-electron bolometer, for measurements in the far-infrared and submillimeter spectral ranges. High performance bolometers can be made using the electron-phonon conductance in heavily doped silicon to provide thermal isolation from the cryogenic bath. Noise performance is expected to be near thermodynamic limits, allowing background limited performance for many far infrared and submillimeter photometric and spectroscopic applications.

  19. JAGUAR Procedures for Detonation Behavior of Silicon Containing Explosives

    NASA Astrophysics Data System (ADS)

    Stiel, Leonard; Baker, Ernest; Capellos, Christos; Poulos, William; Pincay, Jack

    2007-06-01

    Improved relationships for the thermodynamic properties of solid and liquid silicon and silicon oxide for use with JAGUAR thermo-chemical equation of state routines were developed in this study. Analyses of experimental melting temperature curves for silicon and silicon oxide indicated complex phase behavior and that improved coefficients were required for solid and liquid thermodynamic properties. Advanced optimization routines were utilized in conjunction with the experimental melting point data to establish volumetric coefficients for these substances. The new property libraries resulted in agreement with available experimental values, including Hugoniot data at elevated pressures. Detonation properties were calculated with JAGUAR using the revised property libraries for silicon containing explosives. Constants of the JWLB equation of state were established for varying extent of silicon reaction. Supporting thermal heat transfer analyses were conducted for varying silicon particle sizes to establish characteristic times for melting and silicon reaction.

  20. Recent Advances in Silicon Nanomaterial-Based Fluorescent Sensors.

    PubMed

    Wang, Houyu; He, Yao

    2017-02-03

    During the past decades, owing to silicon nanomaterials' unique optical properties, benign biocompatibility, and abundant surface chemistry, different dimensional silicon nanostructures have been widely employed for rationally designing and fabricating high-performance fluorescent sensors for the detection of various chemical and biological species. Among of these, zero-dimensional silicon nanoparticles (SiNPs) and one-dimensional silicon nanowires (SiNWs) are of particular interest. Herein, we focus on reviewing recent advances in silicon nanomaterials-based fluorescent sensors from a broad perspective and discuss possible future directions. Firstly, we introduce the latest achievement of zero-dimensional SiNP-based fluorescent sensors. Next, we present recent advances of one-dimensional SiNW-based fluorescent sensors. Finally, we discuss the major challenges and prospects for the development of silicon-based fluorescent sensors.

  1. Plasmonic engineering of spontaneous emission from silicon nanocrystals.

    PubMed

    Goffard, Julie; Gérard, Davy; Miska, Patrice; Baudrion, Anne-Laure; Deturche, Régis; Plain, Jérôme

    2013-01-01

    Silicon nanocrystals offer huge advantages compared to other semi-conductor quantum dots as they are made from an abundant, non-toxic material and are compatible with silicon devices. Besides, among a wealth of extraordinary properties ranging from catalysis to nanomedicine, metal nanoparticles are known to increase the radiative emission rate of semiconductor quantum dots. Here, we use gold nanoparticles to accelerate the emission of silicon nanocrystals. The resulting integrated hybrid emitter is 5-fold brighter than bare silicon nanocrystals. We also propose an in-depth analysis highlighting the role of the different physical parameters in the photoluminescence enhancement phenomenon. This result has important implications for the practical use of silicon nanocrystals in optoelectronic devices, for instance for the design of efficient down-shifting devices that could be integrated within future silicon solar cells.

  2. Recent Advances in Silicon Nanomaterial-Based Fluorescent Sensors

    PubMed Central

    Wang, Houyu; He, Yao

    2017-01-01

    During the past decades, owing to silicon nanomaterials’ unique optical properties, benign biocompatibility, and abundant surface chemistry, different dimensional silicon nanostructures have been widely employed for rationally designing and fabricating high-performance fluorescent sensors for the detection of various chemical and biological species. Among of these, zero-dimensional silicon nanoparticles (SiNPs) and one-dimensional silicon nanowires (SiNWs) are of particular interest. Herein, we focus on reviewing recent advances in silicon nanomaterials-based fluorescent sensors from a broad perspective and discuss possible future directions. Firstly, we introduce the latest achievement of zero-dimensional SiNP-based fluorescent sensors. Next, we present recent advances of one-dimensional SiNW-based fluorescent sensors. Finally, we discuss the major challenges and prospects for the development of silicon-based fluorescent sensors. PMID:28165357

  3. Photonic Crystal Sensors Based on Porous Silicon

    PubMed Central

    Pacholski, Claudia

    2013-01-01

    Porous silicon has been established as an excellent sensing platform for the optical detection of hazardous chemicals and biomolecular interactions such as DNA hybridization, antigen/antibody binding, and enzymatic reactions. Its porous nature provides a high surface area within a small volume, which can be easily controlled by changing the pore sizes. As the porosity and consequently the refractive index of an etched porous silicon layer depends on the electrochemial etching conditions photonic crystals composed of multilayered porous silicon films with well-resolved and narrow optical reflectivity features can easily be obtained. The prominent optical response of the photonic crystal decreases the detection limit and therefore increases the sensitivity of porous silicon sensors in comparison to sensors utilizing Fabry-Pérot based optical transduction. Development of porous silicon photonic crystal sensors which allow for the detection of analytes by the naked eye using a simple color change or the fabrication of stacked porous silicon photonic crystals showing two distinct optical features which can be utilized for the discrimination of analytes emphasize its high application potential. PMID:23571671

  4. Doping of silicon by carbon during laser ablation process

    NASA Astrophysics Data System (ADS)

    Raciukaitis, G.; Brikas, M.; Kazlauskiene, V.; Miskinis, J.

    2007-04-01

    Effect of laser ablation on properties of remaining material was investigated in silicon. It was established that laser cutting of wafers in air induced doping of silicon by carbon. The effect was found to be more distinct by the use of higher laser power or UV radiation. Carbon ions created bonds with silicon in the depth of silicon. Formation of the silicon carbide type bonds was confirmed by SIMS, XPS and AES measurements. Modeling of the carbon diffusion was performed to clarify its depth profile in silicon. Photo-chemical reactions of such type changed the structure of material and could be a reason for the reduced quality of machining. A controlled atmosphere was applied to prevent carbonization of silicon during laser cutting.

  5. Periodic silicon nanostructures for spectroscopic microsensors

    NASA Astrophysics Data System (ADS)

    Wehrspohn, Ralf B.; Gesemann, Benjamin; Pergande, Daniel; Geppert, Torsten M.; Schweizer, Stefan L.; Moretton, Susanne; Lambrecht, Armin

    2011-09-01

    Periodic silicon nanostructures can be used for different kinds of gas sensors depending on the analyte concentration. First we present an optical gas sensor based on the classical non-dispersive infrared technique for ppm-concentration using ultra-compact photonic crystal gas cells. It is conceptually based on low group velocities inside a photonic crystal gas cell and anti-reflection layers coupling light into the device. Experimentally, an enhancement of the CO2 infrared absorption by a factor of 2.6 to 3.5 as compared to an empty cell, due to slow light inside a 2D silicon photonic crystal gas cell, was observed; this is in excellent agreement with numerical simulations. In addition we report on silicon nanotip arrays, suitable for gas ionization in ion mobility microspectrometers (micro-IMS) having detection ranges in principle down to the ppt-range. Such instruments allow the detection of explosives, chemical warfare agents, and illicit drugs, e.g., at airports. We describe the fabrication process of large-scale-ordered nanotips with different tip shapes. Both silicon microstructures have been fabricated by photoelectrochemical etching of silicon.

  6. Continuous coating of silicon-on-ceramic

    NASA Technical Reports Server (NTRS)

    Heaps, J. D.; Schuldt, S. B.; Grung, B. L.; Zook, J. D.; Butter, C. D.

    1980-01-01

    Growth of sheet silicon on low-cost substrates has been demonstrated by the silicon coating with inverted meniscus (SCIM) technique. A mullite-based ceramic substrate is coated with carbon and then passed over a trough of molten silicon with a raised meniscus. Solidification occurs at the trailing edge of the downstream meniscus, producing a silicon-on-ceramic (SOC) layer. Meniscus shape and stability are controlled by varying the level of molten silicon in a reservoir connected to the trough. The thermal conditions for growth and the crystallographic texture of the SOC layers are similar to those produced by dip-coating, the original technique of meniscus-controlled growth. The thermal conditions for growth have been analyzed in some detail. The analysis correctly predicts the velocity-thickness relationship and the liquid-solid interface shape for dip-coating, and appears to be equally applicable to SCIM-coating. Solar cells made from dip-coated SOC material have demonstrated efficiencies of 10% on 4-sq cm cells and 9.9% on 10-sq cm cells.

  7. Increased longitudinal growth in rats on a silicon-depleted diet☆

    PubMed Central

    Jugdaohsingh, Ravin; Calomme, Mario R.; Robinson, Karen; Nielsen, Forrest; Anderson, Simon H.C.; D'Haese, Patrick; Geusens, Piet; Loveridge, Nigel; Thompson, Richard P.H.; Powell, Jonathan J.

    2008-01-01

    Silicon-deficiency studies in growing animals in the early 1970s reported stunted growth and profound defects in bone and other connective tissues. However, more recent attempts to replicate these findings have found mild alterations in bone metabolism without any adverse health effects. Thus the biological role of silicon remains unknown. Using a specifically formulated silicon-depleted diet and modern methods for silicon analysis and assessment of skeletal development, we undertook, through international collaboration between silicon researchers, an extensive study of long-term silicon depletion on skeletal development in an animal. 21-day old female Sprague–Dawley rats (n = 20) were fed a silicon-depleted diet (3.2 µg Si/g feed) for 26 weeks and their growth and skeletal development were compared with identical rats (n = 10) on the same diet but with silicon added as Si(OH)4 to their drinking water (53.2 µg Si/g water); total silicon intakes were 24 times different. A third group of rats, receiving a standard rodent stock feed (322 µg Si/g feed) and tap water (5 µg Si/g water), served as a reference group for optimal growth. A series of anthropometric and bone quality measures were undertaken during and following the study. Fasting serum silicon concentrations and especially urinary silicon excretion were significantly lower in the silicon-deprived group compared to the supplemented group (P = 0.03 and 0.004, respectively). Tibia and soft-tissue silicon contents did not differ between the two groups, but tibia silicon levels were significantly lower compared to the reference group (P < 0.0001). Outward adverse health effects were not observed in the silicon-deprived group. However, body lengths from week 18 onwards (P < 0.05) and bone lengths at necropsy (P ≤ 0.002) were longer in this group. Moreover, these measures correlated inversely with serum silicon concentrations (P ≤ 0.02). A reduction in bone growth plate thickness and an

  8. Belle II silicon vertex detector

    NASA Astrophysics Data System (ADS)

    Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, Ti.; Baroncelli, To.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Enami, K.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C. W.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rashevskaya, I.; Rao, K. K.; Rizzo, G.; Rozanska, M.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.; Belle II SVD Collaboration

    2016-09-01

    The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.

  9. Purification and deposition of silicon by an iodide disproportionation reaction

    DOEpatents

    Wang, Tihu; Ciszek, Theodore F.

    2002-01-01

    Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

  10. Solution-processed polycrystalline silicon on paper

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Trifunovic, M.; Ishihara, R., E-mail: r.ishihara@tudelft.nl; Shimoda, T.

    Printing electronics has led to application areas which were formerly impossible with conventional electronic processes. Solutions are used as inks on top of large areas at room temperatures, allowing the production of fully flexible circuitry. Commonly, research in these inks have focused on organic and metal-oxide ink materials due to their printability, while these materials lack in the electronic performance when compared to silicon electronics. Silicon electronics, on the other hand, has only recently found their way in solution processes. Printing of cyclopentasilane as the silicon ink has been conducted and devices with far superior electric performance have been mademore » when compared to other ink materials. A thermal annealing step of this material, however, was necessary, which prevented its usage on inexpensive substrates with a limited thermal budget. In this work, we introduce a method that allows polycrystalline silicon (poly-Si) production directly from the same liquid silicon ink using excimer laser irradiation. In this way, poly-Si could be formed directly on top of paper even with a single laser pulse. Using this method, poly-Si transistors were created at a maximum temperature of only 150 °C. This method allows silicon device formation on inexpensive, temperature sensitive substrates such as polyethylene terephthalate, polyethylene naphthalate or paper, which leads to applications that require low-cost but high-speed electronics.« less

  11. Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals.

    PubMed

    Diroll, Benjamin T; Schramke, Katelyn S; Guo, Peijun; Kortshagen, Uwe R; Schaller, Richard D

    2017-10-11

    Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows for selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a subpicosecond change of the dielectric function, resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27%, and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates subpicosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting the modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.

  12. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, R.A.; Mendez, V.P.; Kaplan, S.N.

    1988-11-15

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.

  13. Silicon ribbon stress/strain workshop

    NASA Technical Reports Server (NTRS)

    Leipold, M. H.

    1985-01-01

    Highlights of the Flat Plate Solar Array Project sponsored Silicon Ribbon Stress/Strain Workshop that was held 23 to 24 January 1985 are reported. The presentations and discussions were aimed at acquiring a generic understanding of the sources of stress, deformation, and structural characteristics occurring during the growth of silicon ribbon.

  14. Black thin film silicon

    NASA Astrophysics Data System (ADS)

    Koynov, Svetoslav; Brandt, Martin S.; Stutzmann, Martin

    2011-08-01

    "Black etching" has been proposed previously as a method for the nanoscale texturing of silicon surfaces, which results in an almost complete suppression of reflectivity in the spectral range of absorption relevant for photovoltaics. The method modifies the topmost 150 to 300 nm of the material and thus also is applicable for thin films of silicon. The present work is focused on the optical effects induced by the black-etching treatment on hydrogenated amorphous and microcrystalline silicon thin films, in particular with respect to their application in solar cells. In addition to a strong reduction of the reflectivity, efficient light trapping within the modified thin films is found. The enhancement of the optical absorption due to the light trapping is investigated via photometric measurements and photothermal deflection spectroscopy. The correlation of the texture morphology (characterized via atomic force microscopy) with the optical effects is discussed in terms of an effective medium with gradually varying optical density and in the framework of the theory of statistical light trapping. Photoconductivity spectra directly show that the light trapping causes a significant prolongation of the light path within the black silicon films by up to 15 μm for ˜1 μm thick films, leading to a significant increase of the absorption in the red.

  15. A Serious Complication of Illicit Silicone Injections: Latent Silicone Embolization Syndrome after Incision and Drainage of Local Injection Site.

    PubMed

    Purdy-Payne, Erin K; Green, Jillian; Zenoni, Scott; Evans, Alexander N; Bilski, Tracy R

    2015-08-01

    Silicone embolization syndrome, a serious adverse effect of illicit silicone injections by laypersons, occurs when silicone particles enter the circulation and shower the lungs and other vital organs. We review the literature on silicone embolization syndrome and describe a unique case of the syndrome that developed after a latent period of several months, upon surgical debridement of an injection site abscess. In the scientific literature, silicone embolization syndrome has been well described and multiple presentations have been delineated. Immediate presentation with a rapidly fatal course occurs in cases of erroneous intra-vascular injection, in which large volumes of silicone occlude pulmonary arteries and cause cor pulmonale. Insidious presentation of progressive respiratory distress and systemic inflammatory response syndrome occurs in cases of peri-vascular injection, caused by gradual vascular infiltration by smaller silicone emboli that shower pulmonary capillaries diffusely, causing alveolar hemorrhage and inflammation. Rarely, latent cases have presented months to years later upon trauma to the original site, which disrupts the sequestered siliconoma, allowing re-exposure to the immune system and the opportunity for vascular infiltration. To the best of our knowledge, this is the first description of silicone embolization syndrome that occurred after surgical manipulation of the site. It has important management implications for patients with a history of prior silicone injections at a site being considered for surgical intervention. Strategies for managing this potential complication include adding a regimen of daily debridement, aggressive ventilator support, and maintaining close observation in an intensive care unit (ICU) or progressive care unit (PCU) during the high-risk post-operative period. Alternatively, when possible, surgeons may avoid disruption of the siliconoma by trialing medical management of localized inflammation or using alternative

  16. Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method.

    PubMed

    Ouertani, Rachid; Hamdi, Abderrahmen; Amri, Chohdi; Khalifa, Marouan; Ezzaouia, Hatem

    2014-01-01

    In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.

  17. Iron and its complexes in silicon

    NASA Astrophysics Data System (ADS)

    Istratov, A. A.; Hieslmair, H.; Weber, E. R.

    This article is the first in a series of two reviews on the properties of iron in silicon. It offers a comprehensive of the current state of understanding of fundamental physical properties of iron and its complexes in silicon. The first section of this review discusses the position of iron in the silicon lattice and the electrical properties of interstitial iron. Updated expressions for the solubility and the diffusivity of iron in silicon are presented, and possible explanations for conflicting experimental data obtained by different groups are discussed. The second section of the article considers the electrical and the structural properties of complexes of interstitial iron with shallow acceptors (boron, aluminum, indium, gallium, and thallium), shallow donors (phosphorus and arsenic) and other impurities (gold, silver, platinum, palladium, zinc, sulfur, oxygen, carbon, and hydrogen). Special attention is paid to the kinetics of iron pairing with shallow acceptors, the dissociation of these pairs, and the metastability of iron-acceptor pairs. The parameters of iron-related defects in silicon are summarized in tables that include more than 30 complexes of iron as detected by electron paramagnetic resonance (EPR) and almost 20 energy levels in the band gap associated with iron. The data presented in this review illustrate the enormous complexing activity of iron, which is attributed to the partial or complete (depending on the temperature and the conductivity type) ionization of iron as well as the high diffusivity of iron in silicon. It is shown that studies of iron in silicon require exceptional cleanliness of experimental facilities and highly reproducible diffusion and temperature ramping (quenching) procedures. Properties of iron that are not yet completely understood and need further research are outlined.

  18. Thick silicon growth techniques

    NASA Technical Reports Server (NTRS)

    Bates, H. E.; Mlavsky, A. I.; Jewett, D. N.

    1973-01-01

    Hall mobility measurements on a number of single crystal silicon ribbons grown from graphite dies have shown some ribbons to have mobilities consistent with their resistivities. The behavior of other ribbons appears to be explained by the introduction of impurities of the opposite sign. Growth of a small single crystal silicon ribbon has been achieved from a beryllia dia. Residual internal stresses of the order of 7 to 18,000 psi have been determined to exist in some silicon ribbon, particularly those grown at rates in excess of 1 in./min. Growth experiments have continued toward definition of a configuration and parameters to provide a reasonable yield of single crystal ribbons. High vacuum outgassing of graphite dies and evacuation and backfilling of growth chambers have provided significant improvements in surface quality of ribbons grown from graphite dies.

  19. Process for producing high purity silicon nitride by the direct reaction between elemental silicon and nitrogen-hydrogen liquid reactants

    DOEpatents

    Pugar, Eloise A.; Morgan, Peter E. D.

    1990-01-01

    A process is disclosed for producing, at a low temperature, a high purity reaction product consisting essentially of silicon, nitrogen, and hydrogen which can then be heated to produce a high purity alpha silicon nitride. The process comprises: reacting together a particulate elemental high purity silicon with a high purity nitrogen-hydrogen reactant in its liquid state (such as ammonia or hydrazine) having the formula: N.sub.n H.sub.(n+m) wherein: n=1-4 and m=2 when the nitrogen-hydrogen reactant is straight chain, and 0 when the nitrogen-hydrogen reactant is cyclic. High purity silicon nitride can be formed from this intermediate product by heating the intermediate product at a temperature of from about 1200.degree.-1700.degree. C. for a period from about 15 minutes up to about 2 hours to form a high purity alpha silicon nitride product. The discovery of the existence of a soluble Si-N-H intermediate enables chemical pathways to be explored previously unavailable in conventional solid state approaches to silicon-nitrogen ceramics.

  20. Process for producing high purity silicon nitride by the direct reaction between elemental silicon and nitrogen-hydrogen liquid reactants

    DOEpatents

    Pugar, E.A.; Morgan, P.E.D.

    1987-09-15

    A process is disclosed for producing, at a low temperature, a high purity reaction product consisting essentially of silicon, nitrogen, and hydrogen which can then be heated to produce a high purity alpha silicon nitride. The process comprises: reacting together a particulate elemental high purity silicon with a high purity nitrogen-hydrogen reactant in its liquid state (such as ammonia or hydrazine) having the formula: N/sub n/H/sub (n+m)/ wherein: n = 1--4 and m = 2 when the nitrogen-hydrogen reactant is straight chain, and 0 when the nitrogen-hydrogen reactant is cyclic. High purity silicon nitride can be formed from this intermediate product by heating the intermediate product at a temperature of from about 1200--1700/degree/C for a period from about 15 minutes up to about 2 hours to form a high purity alpha silicon nitride product. The discovery of the existence of a soluble Si/endash/N/endash/H intermediate enables chemical pathways to be explored previously unavailable in conventional solid-state approaches to silicon-nitrogen ceramics

  1. Silicon photonics cloud (SiCloud)

    NASA Astrophysics Data System (ADS)

    DeVore, Peter T. S.; Jiang, Yunshan; Lynch, Michael; Miyatake, Taira; Carmona, Christopher; Chan, Andrew C.; Muniam, Kuhan; Jalali, Bahram

    2015-02-01

    We present SiCloud (Silicon Photonics Cloud), the first free, instructional web-based research and education tool for silicon photonics. SiCloud's vision is to provide a host of instructional and research web-based tools. Such interactive learning tools enhance traditional teaching methods by extending access to a very large audience, resulting in very high impact. Interactive tools engage the brain in a way different from merely reading, and so enhance and reinforce the learning experience. Understanding silicon photonics is challenging as the topic involves a wide range of disciplines, including material science, semiconductor physics, electronics and waveguide optics. This web-based calculator is an interactive analysis tool for optical properties of silicon and related material (SiO2, Si3N4, Al2O3, etc.). It is designed to be a one stop resource for students, researchers and design engineers. The first and most basic aspect of Silicon Photonics is the Material Parameters, which provides the foundation for the Device, Sub-System and System levels. SiCloud includes the common dielectrics and semiconductors for waveguide core, cladding, and photodetection, as well as metals for electrical contacts. SiCloud is a work in progress and its capability is being expanded. SiCloud is being developed at UCLA with funding from the National Science Foundation's Center for Integrated Access Networks (CIAN) Engineering Research Center.

  2. Silicon Nitride Equation of State

    NASA Astrophysics Data System (ADS)

    Swaminathan, Pazhayannur; Brown, Robert

    2015-06-01

    This report presents the development a global, multi-phase equation of state (EOS) for the ceramic silicon nitride (Si3N4) . Structural forms include amorphous silicon nitride normally used as a thin film and three crystalline polymorphs. Crystalline phases include hexagonal α-Si3N4, hexagonalβ-Si3N4, and the cubic spinel c-Si3N4. Decomposition at about 1900 °C results in a liquid silicon phase and gas phase products such as molecular nitrogen, atomic nitrogen, and atomic silicon. The silicon nitride EOS was developed using EOSPro which is a new and extended version of the PANDA II code. Both codes are valuable tools and have been used successfully for a variety of material classes. Both PANDA II and EOSPro can generate a tabular EOS that can be used in conjunction with hydrocodes. The paper describes the development efforts for the component solid phases and presents results obtained using the EOSPro phase transition model to investigate the solid-solid phase transitions in relation to the available shock data. Furthermore, the EOSPro mixture model is used to develop a model for the decomposition products and then combined with the single component solid models to study the global phase diagram. Sponsored by the NASA Goddard Space Flight Center Living With a Star program office.

  3. Thermal (Silicon Diode) Data Acquisition Systems

    NASA Technical Reports Server (NTRS)

    Wright, Ernest; Kegley, Jeff

    2008-01-01

    Marshall Space Flight Center s X-ray Cryogenic Facility (XRCF) has been performing cryogenic testing to 20 Kelvin since 1999. Two configurations for acquiring data from silicon diode temperature sensors have been implemented at the facility. The facility's environment is recorded via a data acquisition system capable of reading up to 60 silicon diodes. Test article temperature is recorded by a second data acquisition system capable of reading 150+ silicon diodes. The specifications and architecture of both systems will be presented.

  4. Thermal (Silicon Diode) Data Acquisition System

    NASA Technical Reports Server (NTRS)

    Kegley, Jeffrey

    2008-01-01

    Marshall Space Flight Center's X-ray Calibration Facility (XRCF) has been performing cryogenic testing to 20 Kelvin since 1999. Two configurations for acquiring data from silicon diode temperature sensors have been implemented at the facility. The facility's environment is recorded via a data acquisition system capable of reading up to 60 silicon diodes. Test article temperature is recorded by a second data acquisition system capable of reading 150+ silicon diodes. The specifications and architecture of both systems will be presented.

  5. Powder containing 2H-type silicon carbide produced by reacting silicon dioxide and carbon powder in nitrogen atmosphere in the presence of aluminum

    NASA Technical Reports Server (NTRS)

    Kuramoto, N.; Takiguchi, H.

    1984-01-01

    The production of powder which contains silicon carbide consisting of 40% of 2H-type silicon carbide, beta type silicon carbide and less than 3% of nitrogen is discussed. The reaction temperature to produce the powder containing 40% of 2H-type silicon carbide is set at above 1550 degrees C in an atmosphere of aluminum or aluminum compounds and nitrogen gas or an antioxidation atmosphere containing nitrogen gas. The mixture ratio of silicon dioxide and carbon powder is 0.55 - 1:2.0 and the contents of aluminum or aluminum compounds within silicon dioxide is less than 3% in weight.

  6. Silicon production process evaluations

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The chemical engineering analysis of the preliminary process design of a process for producing solar cell grade silicon from dichlorosilane is presented. A plant to produce 1,000 MT/yr of silicon is analyzed. Progress and status for the plant design are reported for the primary activities of base case conditions (60 percent), reaction chemistry (50 percent), process flow diagram (35 percent), energy balance (10 percent), property data (10 percent) and equipment design (5 percent).

  7. Formation of copper precipitates in silicon

    NASA Astrophysics Data System (ADS)

    Flink, Christoph; Feick, Henning; McHugo, Scott A.; Mohammed, Amna; Seifert, Winfried; Hieslmair, Henry; Heiser, Thomas; Istratov, Andrei A.; Weber, Eicke R.

    1999-12-01

    The formation of copper precipitates in silicon was studied after high-temperature intentional contamination of p- and n-type FZ and Cz-grown silicon and quench to room temperature. With the Transient Ion Drift (TID) technique on p-type silicon a critical Fermi level position at EC-0.2 eV was found. Only if the Fermi level position, which is determined by the concentrations of the acceptors and the copper donors, surpasses this critical value precipitation takes place. If the Fermi level is below this level the supersaturated interstitial copper diffuses out. An electrostatic precipitation model is introduced that correlates the observed precipitation behavior with the electrical activity of the copper precipitates as detected with Deep Level Transient Spectroscopy (DLTS) on n-type and with Minority Carrier Transient Spectroscopy (MCTS) on p-type silicon.

  8. Monolithically interconnected silicon-film™ module technology

    NASA Astrophysics Data System (ADS)

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

    1999-03-01

    AstroPower is developing an advanced thin-silicon-based, photovoltaic module product. A low-cost monolithic interconnected device is being integrated into a module that combines the design and process features of advanced light trapped, thin-silicon solar cells. This advanced product incorporates a low-cost substrate, a nominally 50-μm thick grown silicon layer with minority carrier diffusion lengths exceeding the active layer thickness, light trapping due to back-surface reflection, and back-surface passivation. The thin silicon layer enables high solar cell performance and can lead to a module conversion efficiency as high as 19%. These performance design features, combined with low-cost manufacturing using relatively low-cost capital equipment, continuous processing and a low-cost substrate, will lead to high-performance, low-cost photovoltaic panels.

  9. Multispectral imaging with vertical silicon nanowires

    PubMed Central

    Park, Hyunsung; Crozier, Kenneth B.

    2013-01-01

    Multispectral imaging is a powerful tool that extends the capabilities of the human eye. However, multispectral imaging systems generally are expensive and bulky, and multiple exposures are needed. Here, we report the demonstration of a compact multispectral imaging system that uses vertical silicon nanowires to realize a filter array. Multiple filter functions covering visible to near-infrared (NIR) wavelengths are simultaneously defined in a single lithography step using a single material (silicon). Nanowires are then etched and embedded into polydimethylsiloxane (PDMS), thereby realizing a device with eight filter functions. By attaching it to a monochrome silicon image sensor, we successfully realize an all-silicon multispectral imaging system. We demonstrate visible and NIR imaging. We show that the latter is highly sensitive to vegetation and furthermore enables imaging through objects opaque to the eye. PMID:23955156

  10. Measuring the reactivity of a silicon-terminated probe

    NASA Astrophysics Data System (ADS)

    Sweetman, Adam; Stirling, Julian; Jarvis, Samuel Paul; Rahe, Philipp; Moriarty, Philip

    2016-09-01

    It is generally accepted that the exposed surfaces of silicon crystals are highly reactive due to the dangling bonds which protrude into the vacuum. However, surface reconstruction not only modifies the reactivity of bulk silicon crystals, but also plays a key role in determining the properties of silicon nanocrystals. In this study we probe the reactivity of silicon clusters at the end of a scanning probe tip by examining their interaction with closed-shell fullerene molecules. Counter to intuitive expectations, many silicon clusters do not react strongly with the fullerene cage, and we find that only specific highly oriented clusters have sufficient reactivity to break open the existing carbon-carbon bonds.

  11. Silicon nanopillars for field enhanced surface spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wells, Sabrina M; Merkulov, Igor A; Kravchenko, Ivan I

    Silicon nanowire and nanopillar structures have continued to draw increased attention in recent years due in part to their unique optical properties. Herein, electron beam lithography combined with reactive-ion etching is used to reproducibly create individual silicon nanopillars of various sizes, shapes, and heights. Finite difference time domain numerical analysis predicts enhancements in localized fields in the vicinity of appropriately-sized and coaxially-illuminated silicon nanopillars of approximately two orders of magnitude. By analyzing experimentally measured strength of the silicon Raman phonon line (500 cm-1), it was determined that nanopillars produced field enhancement that are consistent with these predictions. Additionally, we demonstratemore » that a thin layer of Zn phthalocyanine deposited on the nanopillar surface produced prominent Raman spectra yielding enhancement factors (EFs) better than 300. Finally, silicon nanopillars of cylindrical and elliptical shapes were labeled with different fluorophors and evaluated for their surface enhanced fluorescence (SEF) capability. The EF derived from analysis of the acquired fluorescence microscopy images indicate that silicon nanopillar structures can provide enhancement comparable or even stronger than those typically achieved using plasmonic SEF structures without the drawbacks of the metal-based substrates. It is anticipated that scaled up arrays of silicon nanopillars will enable SEF assays with extremely high sensitivity, while a broader impact of the reported phenomena are anticipated in photovoltaics, subwavelength light focusing, and fundamental nanophotonics.« less

  12. Silicon material technology status. [assessment for electronic and photovoltaic applications

    NASA Technical Reports Server (NTRS)

    Lutwack, R.

    1983-01-01

    Silicon has been the basic element for the electronic and photovoltaic industries. The use of silicon as the primary element for terrestrial photovoltaic solar arrays is projected to continue. The reasons for this projection are related to the maturity of silicon technology, the ready availability of extremely pure silicon, the performance of silicon solar cells, and the considerable present investment in technology and manufacturing facilities. The technologies for producing semiconductor grade silicon and, to a lesser extent, refined metallurgical grade silicon are considered. It is pointed out that nearly all of the semiconductor grade silicon is produced by processes based on the Siemens deposition reactor, a technology developed 26 years ago. The state-of-the-art for producing silicon by this process is discussed. It is expected that efforts to reduce polysilicon process costs will continue.

  13. Low cost silicon-on-ceramic photovoltaic solar cells

    NASA Technical Reports Server (NTRS)

    Koepke, B. G.; Heaps, J. D.; Grung, B. L.; Zook, J. D.; Sibold, J. D.; Leipold, M. H.

    1980-01-01

    A technique has been developed for coating low-cost mullite-based refractory substrates with thin layers of solar cell quality silicon. The technique involves first carbonizing one surface of the ceramic and then contacting it with molten silicon. The silicon wets the carbonized surface and, under the proper thermal conditions, solidifies as a large-grained sheet. Solar cells produced from this composite silicon-on-ceramic material have exhibited total area conversion efficiencies of ten percent.

  14. Ion irradiation of the native oxide/silicon surface increases the thermal boundary conductance across aluminum/silicon interfaces

    NASA Astrophysics Data System (ADS)

    Gorham, Caroline S.; Hattar, Khalid; Cheaito, Ramez; Duda, John C.; Gaskins, John T.; Beechem, Thomas E.; Ihlefeld, Jon F.; Biedermann, Laura B.; Piekos, Edward S.; Medlin, Douglas L.; Hopkins, Patrick E.

    2014-07-01

    The thermal boundary conductance across solid-solid interfaces can be affected by the physical properties of the solid boundary. Atomic composition, disorder, and bonding between materials can result in large deviations in the phonon scattering mechanisms contributing to thermal boundary conductance. Theoretical and computational studies have suggested that the mixing of atoms around an interface can lead to an increase in thermal boundary conductance by creating a region with an average vibrational spectra of the two materials forming the interface. In this paper, we experimentally demonstrate that ion irradiation and subsequent modification of atoms at solid surfaces can increase the thermal boundary conductance across solid interfaces due to a change in the acoustic impedance of the surface. We measure the thermal boundary conductance between thin aluminum films and silicon substrates with native silicon dioxide layers that have been subjected to proton irradiation and post-irradiation surface cleaning procedures. The thermal boundary conductance across the Al/native oxide/Si interfacial region increases with an increase in proton dose. Supported with statistical simulations, we hypothesize that ion beam mixing of the native oxide and silicon substrate within ˜2.2nm of the silicon surface results in the observed increase in thermal boundary conductance. This ion mixing leads to the spatial gradation of the silicon native oxide into the silicon substrate, which alters the acoustic impedance and vibrational characteristics at the interface of the aluminum film and native oxide/silicon substrate. We confirm this assertion with picosecond acoustic analyses. Our results demonstrate that under specific conditions, a "more disordered and defected" interfacial region can have a lower resistance than a more "perfect" interface.

  15. Advanced Silicon-on-Insulator: Crystalline Silicon on Atomic Layer Deposited Beryllium Oxide.

    PubMed

    Min Lee, Seung; Hwan Yum, Jung; Larsen, Eric S; Chul Lee, Woo; Keun Kim, Seong; Bielawski, Christopher W; Oh, Jungwoo

    2017-10-16

    Silicon-on-insulator (SOI) technology improves the performance of devices by reducing parasitic capacitance. Devices based on SOI or silicon-on-sapphire technology are primarily used in high-performance radio frequency (RF) and radiation sensitive applications as well as for reducing the short channel effects in microelectronic devices. Despite their advantages, the high substrate cost and overheating problems associated with complexities in substrate fabrication as well as the low thermal conductivity of silicon oxide prevent broad applications of this technology. To overcome these challenges, we describe a new approach of using beryllium oxide (BeO). The use of atomic layer deposition (ALD) for producing this material results in lowering the SOI wafer production cost. Furthermore, the use of BeO exhibiting a high thermal conductivity might minimize the self-heating issues. We show that crystalline Si can be grown on ALD BeO and the resultant devices exhibit potential for use in advanced SOI technology applications.

  16. Development of a continuous spinning process for producing silicon carbide - silicon nitride precursor fibers

    NASA Technical Reports Server (NTRS)

    1985-01-01

    An apparatus was designed for the continuous production of silicon carbide - silicon nitride precursor fibers. The precursor polymer can be fiberized, crosslined and pyrolyzed. The product is a metallic black fiber with the composition of the type C sub x Si sub y n sub z. Little, other than the tensile strength and modulus of elasticity, is known of the physical properties.

  17. Thin silicon foils produced by epoxy-induced spalling of silicon for high efficiency solar cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Martini, R., E-mail: roberto.martini@imec.be; imec, Kapeldreef 75, 3001 Leuven; Kepa, J.

    2014-10-27

    We report on the drastic improvement of the quality of thin silicon foils produced by epoxy-induced spalling. In the past, researchers have proposed to fabricate silicon foils by spalling silicon substrates with different stress-inducing materials to manufacture thin silicon solar cells. However, the reported values of effective minority carrier lifetime of the fabricated foils remained always limited to ∼100 μs or below. In this work, we investigate epoxy-induced exfoliated foils by electron spin resonance to analyze the limiting factors of the minority carrier lifetime. These measurements highlight the presence of disordered dangling bonds and dislocation-like defects generated by the exfoliation process.more » A solution to remove these defects compatible with the process flow to fabricate solar cells is proposed. After etching off less than 1 μm of material, the lifetime of the foil increases by more than a factor of 4.5, reaching a value of 461 μs. This corresponds to a lower limit of the diffusion length of more than 7 times the foil thickness. Regions with different lifetime correlate well with the roughness of the crack surface which suggests that the lifetime is now limited by the quality of the passivation of rough surfaces. The reported values of the minority carrier lifetime show a potential for high efficiency (>22%) thin silicon solar cells.« less

  18. Silicon nanomaterials platform for bioimaging, biosensing, and cancer therapy.

    PubMed

    Peng, Fei; Su, Yuanyuan; Zhong, Yiling; Fan, Chunhai; Lee, Shuit-Tong; He, Yao

    2014-02-18

    Silicon nanomaterials are an important class of nanomaterials with great potential for technologies including energy, catalysis, and biotechnology, because of their many unique properties, including biocompatibility, abundance, and unique electronic, optical, and mechanical properties, among others. Silicon nanomaterials are known to have little or no toxicity due to favorable biocompatibility of silicon, which is an important precondition for biological and biomedical applications. In addition, huge surface-to-volume ratios of silicon nanomaterials are responsible for their unique optical, mechanical, or electronic properties, which offer exciting opportunities for design of high-performance silicon-based functional nanoprobes, nanosensors, and nanoagents for biological analysis and detection and disease treatment. Moreover, silicon is the second most abundant element (after oxygen) on earth, providing plentiful and inexpensive resources for large-scale and low-cost preparation of silicon nanomaterials for practical applications. Because of these attractive traits, and in parallel with a growing interest in their design and synthesis, silicon nanomaterials are extensively investigated for wide-ranging applications, including energy, catalysis, optoelectronics, and biology. Among them, bioapplications of silicon nanomaterials are of particular interest. In the past decade, scientists have made an extensive effort to construct a silicon nanomaterials platform for various biological and biomedical applications, such as biosensors, bioimaging, and cancer treatment, as new and powerful tools for disease diagnosis and therapy. Nonetheless, there are few review articles covering these important and promising achievements to promote the awareness of development of silicon nanobiotechnology. In this Account, we summarize recent representative works to highlight the recent developments of silicon functional nanomaterials for a new, powerful platform for biological and

  19. Fluidized-Bed Cleaning of Silicon Particles

    NASA Technical Reports Server (NTRS)

    Rohatgi, Naresh K.; Hsu, George C.

    1987-01-01

    Fluidized-bed chemical cleaning process developed to remove metallic impurities from small silicon particles. Particles (250 micrometer in size) utilized as seed material in silane pyrolysis process for production of 1-mm-size silicon. Product silicon (1 mm in size) used as raw material for fabrication of solar cells and other semiconductor devices. Principal cleaning step is wash in mixture of hydrochloric and nitric acids, leaching out metals and carrying them away as soluble chlorides. Particles fluidized by cleaning solution to assure good mixing and uniform wetting.

  20. Silicon-on Ceramic Process: Silicon Sheet Growth and Device Development for the Large-area Silicon Sheet and Cell Development Tasks of the Low-cost Solar Array Project

    NASA Technical Reports Server (NTRS)

    Chapman, P. W.; Zook, J. D.; Heaps, J. D.; Grung, B. L.; Koepke, B.; Schuldt, S. B.

    1979-01-01

    The technical and economic feasibility of producing solar cell-quality silicon was investigated. This was done by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. Significant progress in the following areas was demonstrated: (1) fabricating a 10 sq cm cell having 9.9 percent conversion efficiency; (2) producing a 225 sq cm layer of sheet silicon; and (3) obtaining 100 microns thick coatings at pull speed of 0.15 cm/sec, although approximately 50 percent of the layer exhibited dendritic growth.

  1. Laser wafering for silicon solar.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Friedmann, Thomas Aquinas; Sweatt, William C.; Jared, Bradley Howell

    2011-03-01

    Current technology cuts solar Si wafers by a wire saw process, resulting in 50% 'kerf' loss when machining silicon from a boule or brick into a wafer. We want to develop a kerf-free laser wafering technology that promises to eliminate such wasteful wire saw processes and achieve up to a ten-fold decrease in the g/W{sub p} (grams/peak watt) polysilicon usage from the starting polysilicon material. Compared to today's technology, this will also reduce costs ({approx}20%), embodied energy, and green-house gas GHG emissions ({approx}50%). We will use short pulse laser illumination sharply focused by a solid immersion lens to produce subsurfacemore » damage in silicon such that wafers can be mechanically cleaved from a boule or brick. For this concept to succeed, we will need to develop optics, lasers, cleaving, and high throughput processing technologies capable of producing wafers with thicknesses < 50 {micro}m with high throughput (< 10 sec./wafer). Wafer thickness scaling is the 'Moore's Law' of silicon solar. Our concept will allow solar manufacturers to skip entire generations of scaling and achieve grid parity with commercial electricity rates. Yet, this idea is largely untested and a simple demonstration is needed to provide credibility for a larger scale research and development program. The purpose of this project is to lay the groundwork to demonstrate the feasibility of laser wafering. First, to design and procure on optic train suitable for producing subsurface damage in silicon with the required damage and stress profile to promote lateral cleavage of silicon. Second, to use an existing laser to produce subsurface damage in silicon, and third, to characterize the damage using scanning electron microscopy and confocal Raman spectroscopy mapping.« less

  2. Impurities in silicon solar cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.

    1985-01-01

    Metallic impurities, both singly and in combinations, affect the performance of silicon solar cells. Czochralski silicon web crystals were grown with controlled additions of secondary impurities. The primary electrical dopants were boron and phosphorus. The silicon test ingots were grown under controlled and carefully monitored conditions from high-purity charge and dopant material to minimize unintentional contamination. Following growth, each crystal was characterized by chemical, microstructural, electrical, and solar cell tests to provide a detailed and internally consistent description of the relationships between silicon impurity concentration and solar cell performance. Deep-level spectroscopy measurements were used to measure impurity concentrations at levels below the detectability of other techniques and to study thermally-induced changes in impurity activity. For the majority of contaminants, impurity-induced performance loss is due to a reduction of the base diffusion length. From these observations, a semi-empirical model which predicts cell performance as a function of metal impurity concentration was formulated. The model was then used successfully to predict the behavior of solar cells bearing as many as 11 different impurities.

  3. Silica substrate or portion formed from oxidation of monocrystalline silicon

    DOEpatents

    Matzke, Carolyn M.; Rieger, Dennis J.; Ellis, Robert V.

    2003-07-15

    A method is disclosed for forming an inclusion-free silica substrate using a monocrystalline silicon substrate as the starting material and oxidizing the silicon substrate to convert it entirely to silica. The oxidation process is performed from both major surfaces of the silicon substrate using a conventional high-pressure oxidation system. The resulting product is an amorphous silica substrate which is expected to have superior etching characteristics for microfabrication than conventional fused silica substrates. The present invention can also be used to convert only a portion of a monocrystalline silicon substrate to silica by masking the silicon substrate and locally thinning a portion the silicon substrate prior to converting the silicon portion entirely to silica. In this case, the silica formed by oxidizing the thinned portion of the silicon substrate can be used, for example, as a window to provide optical access through the silicon substrate.

  4. Electrochemical Deposition of High Purity Silicon from Molten Salts

    NASA Astrophysics Data System (ADS)

    Haarberg, Geir Martin

    Several approaches were tried in order to develop an electrochemical route for producing high purity silicon from molten salts. SiO2, K2SiF6 and metallurgical silicon were used as the source of silicon. Molten electrolytes based on chloride (CaCl2-NaCl) and fluoride (LiF-KF) at temperatures from 550 - 900 oC were used. Transient electrochemical techniques were used to study the electrochemical behaviour of dissolved silicon species. Electrolysis experiments were carried out to deposit silicon.

  5. Electrochemical Deposition of High Purity Silicon in Molten Salts

    NASA Astrophysics Data System (ADS)

    Haarberg, Geir Martin

    Several approaches were tried in order to develop an electrochemical route for producing high purity silicon from molten salts. SiO2, K2SiF6 and metallurgical silicon were used as the source of silicon. Molten electrolytes based on chloride (CaCl2-NaCl) and fluoride (LiF-KF) at temperatures from 550 - 900 °C were used. Transient electrochemical techniques were used to study the electrochemical behaviour of dissolved silicon species. Electrolysis experiments were carried out to deposit silicon.

  6. Application Of Optical Processing For Growth Of Silicon Dioxide

    DOEpatents

    Sopori, Bhushan L.

    1997-06-17

    A process for producing a silicon dioxide film on a surface of a silicon substrate. The process comprises illuminating a silicon substrate in a substantially pure oxygen atmosphere with a broad spectrum of visible and infrared light at an optical power density of from about 3 watts/cm.sup.2 to about 6 watts/cm.sup.2 for a time period sufficient to produce a silicon dioxide film on the surface of the silicon substrate. An optimum optical power density is about 4 watts/cm.sup.2 for growth of a 100.ANG.-300.ANG. film at a resultant temperature of about 400.degree. C. Deep level transient spectroscopy analysis detects no measurable impurities introduced into the silicon substrate during silicon oxide production and shows the interface state density at the SiO.sub.2 /Si interface to be very low.

  7. Critical technology limits to silicon material and sheet production

    NASA Technical Reports Server (NTRS)

    Leipold, M. H.

    1982-01-01

    Earlier studies have indicated that expenditures related to the preparation of high-purity silicon and its conversion to silicon sheet represent from 40 to 52 percent of the cost of the entire panel. The present investigation is concerned with the elements which were selected for study in connection with the Flat-Plate Solar Array (FSA) Project. The first of two technologies which are being developed within the FSA Project involves the conversion of metallurgical-grade silicon through a silane purification process to silicon particles. The second is concerned with the conversion of trichlorosilane to dichlorosilane, and the subsequent production of silicon using modified rod reactors of the Siemens type. With respect to silicon sheet preparation, efforts have been focused both on the preparation of ingots, followed by wafering, and the direct crystallization of molten silicon into a ribbon or film.

  8. A metallurgical route to solar-grade silicon

    NASA Technical Reports Server (NTRS)

    Schei, A.

    1986-01-01

    The aim of the process is to produce silicon for crystallization into ingots that can be sliced to wafers for processing into photovoltaic cells. If the potential purity can be realized, the silicon will also be applicable for ribbon pulling techniques where the purification during crystallization is negligible. The process consists of several steps: selection and purification of raw materials, carbothermic reduction of silica, ladle treatment, casting, crushing, leaching, and melting. The leaching step is crucial for high purity, and the obtainable purity is determined by the solidification before leaching. The most difficult specifications to fulfill are the low contents of boron, phosphorus, and carbon. Boron and phosphorus can be excluded from the raw materials, but the carbothermic reduction will unavoidably saturate the silicon with carbon at high temperature. During cooling carbon will precipitate as silicon carbide crystals, which will be harmful in solar cells. The cost of this solar silicon will depend strongly on the scale of production. It is as yet premature to give exact figures, but with a scale of some thousand tons per year, the cost will only be a few times the cost of ordinary metallurgical silicon.

  9. Neuromorphic photonic networks using silicon photonic weight banks.

    PubMed

    Tait, Alexander N; de Lima, Thomas Ferreira; Zhou, Ellen; Wu, Allie X; Nahmias, Mitchell A; Shastri, Bhavin J; Prucnal, Paul R

    2017-08-07

    Photonic systems for high-performance information processing have attracted renewed interest. Neuromorphic silicon photonics has the potential to integrate processing functions that vastly exceed the capabilities of electronics. We report first observations of a recurrent silicon photonic neural network, in which connections are configured by microring weight banks. A mathematical isomorphism between the silicon photonic circuit and a continuous neural network model is demonstrated through dynamical bifurcation analysis. Exploiting this isomorphism, a simulated 24-node silicon photonic neural network is programmed using "neural compiler" to solve a differential system emulation task. A 294-fold acceleration against a conventional benchmark is predicted. We also propose and derive power consumption analysis for modulator-class neurons that, as opposed to laser-class neurons, are compatible with silicon photonic platforms. At increased scale, Neuromorphic silicon photonics could access new regimes of ultrafast information processing for radio, control, and scientific computing.

  10. Fabricating amorphous silicon solar cells by varying the temperature _of the substrate during deposition of the amorphous silicon layer

    DOEpatents

    Carlson, David E.

    1982-01-01

    An improved process for fabricating amorphous silicon solar cells in which the temperature of the substrate is varied during the deposition of the amorphous silicon layer is described. Solar cells manufactured in accordance with this process are shown to have increased efficiencies and fill factors when compared to solar cells manufactured with a constant substrate temperature during deposition of the amorphous silicon layer.

  11. Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method

    PubMed Central

    2014-01-01

    In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films. PMID:25349554

  12. Sampling Artifacts from Conductive Silicone Tubing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse

    2009-05-15

    We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: 1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and 2) silicone tubing emits organic contaminants containing siloxane that adsorb onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosolmore » mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and should, therefore, be used with caution. Gentle heating, physical and chemical properties of the particle carriers, exposure to solvents, and tubing age may influence siloxane uptake. The amount of contamination is expected to increase as the tubing surface area increases and as the particle surface area increases. The effect is observed at ambient temperature and enhanced by mild heating (<100 oC). Further evaluation is warranted.« less

  13. Athermal Annealing of Silicon

    NASA Astrophysics Data System (ADS)

    Fischer, R. P.; Grun, J.; Ting, A.; Felix, C.; Peckerar, M.; Fatemi, M.; Manka, C. K.

    1999-11-01

    Current semiconductor annealing methods are based on thermal processes which are accompanied by diffusion that degrades the definition of device features or causes other problems. This will be a serious obstacle for the production of next-generation ultra-high density, low power semiconductor devices. Experiments underway at NRL utilize a new annealing method which is much faster than thermal annealing and does not depend upon thermal energy (J. Grun, et al)., Phys. Rev. Letters 78, 1584 (1997).. A 10 J, 30 nsec, 1.053 nm wavelength laser pulse is focussed to approximately 1 mm diameter on a silicon sample. Acoustic and shock waves propagate from the impact region, which deposit mechanical energy into the material and anneal the silicon. Experimental results will be presented on annealing neutron-transmutation-doped (NTD) and ion implanted silicon samples with impurity concentrations from 1 × 10^15-3 × 10^20/cm^3.

  14. Gas Atmospheres Improve Silicon-Ribbon Quality

    NASA Technical Reports Server (NTRS)

    Wald, F. V.; Kalejs, J. P.

    1985-01-01

    Growing crystal surrounded by gas containing carbon or oxygen. Ribbon of solid silicon, edgewise, grows from pool of molten silicon in die. Gases flowing through orifice ensure longer diffusion length and less contaminiation by carbide particles in product.

  15. Analysis of silicon stress/strain relationships

    NASA Technical Reports Server (NTRS)

    Dillon, O.

    1986-01-01

    Results are presented for work on stress-strain relationships in silicon ribbon. Calculations of stress fields, dislocation desities, and buckling were made; uniaxial tensile tests were made on silicon at 1150 C; and dislocation motion studies were performed.

  16. Sublid Speeds Growth Of Silicon Ribbon

    NASA Technical Reports Server (NTRS)

    Seidensticker, R. G.; Mchugh, J. P.

    1988-01-01

    Heat shield permits enhancement of exit cooling without formation of unwanted crystals. Thermal barrier between molten silicon and lid of susceptor and crucible allows solidifying ribbon of silicon to be withdrawn faster. Barrier, or sublid, increases production rate.

  17. Hyperdoping silicon with selenium: solid vs. liquid phase epitaxy

    PubMed Central

    Zhou, Shengqiang; Liu, Fang; Prucnal, S.; Gao, Kun; Khalid, M.; Baehtz, C.; Posselt, M.; Skorupa, W.; Helm, M.

    2015-01-01

    Chalcogen-hyperdoped silicon shows potential applications in silicon-based infrared photodetectors and intermediate band solar cells. Due to the low solid solubility limits of chalcogen elements in silicon, these materials were previously realized by femtosecond or nanosecond laser annealing of implanted silicon or bare silicon in certain background gases. The high energy density deposited on the silicon surface leads to a liquid phase and the fast recrystallization velocity allows trapping of chalcogen into the silicon matrix. However, this method encounters the problem of surface segregation. In this paper, we propose a solid phase processing by flash-lamp annealing in the millisecond range, which is in between the conventional rapid thermal annealing and pulsed laser annealing. Flash lamp annealed selenium-implanted silicon shows a substitutional fraction of ~ 70% with an implanted concentration up to 2.3%. The resistivity is lower and the carrier mobility is higher than those of nanosecond pulsed laser annealed samples. Our results show that flash-lamp annealing is superior to laser annealing in preventing surface segregation and in allowing scalability. PMID:25660096

  18. Luneburg lens in silicon photonics.

    PubMed

    Di Falco, Andrea; Kehr, Susanne C; Leonhardt, Ulf

    2011-03-14

    The Luneburg lens is an aberration-free lens that focuses light from all directions equally well. We fabricated and tested a Luneburg lens in silicon photonics. Such fully-integrated lenses may become the building blocks of compact Fourier optics on chips. Furthermore, our fabrication technique is sufficiently versatile for making perfect imaging devices on silicon platforms.

  19. Silicon Carbide Integrated Circuit Chip

    NASA Image and Video Library

    2015-02-17

    A multilevel interconnect silicon carbide integrated circuit chip with co-fired ceramic package and circuit board recently developed at the NASA GRC Smart Sensors and Electronics Systems Branch for high temperature applications. High temperature silicon carbide electronics and compatible packaging technologies are elements of instrumentation for aerospace engine control and long term inner-solar planet explorations.

  20. Amorphous silicon solar cell allowing infrared transmission

    DOEpatents

    Carlson, David E.

    1979-01-01

    An amorphous silicon solar cell with a layer of high index of refraction material or a series of layers having high and low indices of refraction material deposited upon a transparent substrate to reflect light of energies greater than the bandgap energy of the amorphous silicon back into the solar cell and transmit solar radiation having an energy less than the bandgap energy of the amorphous silicon.

  1. Method for fabricating pixelated silicon device cells

    DOEpatents

    Nielson, Gregory N.; Okandan, Murat; Cruz-Campa, Jose Luis; Nelson, Jeffrey S.; Anderson, Benjamin John

    2015-08-18

    A method, apparatus and system for flexible, ultra-thin, and high efficiency pixelated silicon or other semiconductor photovoltaic solar cell array fabrication is disclosed. A structure and method of creation for a pixelated silicon or other semiconductor photovoltaic solar cell array with interconnects is described using a manufacturing method that is simplified compared to previous versions of pixelated silicon photovoltaic cells that require more microfabrication steps.

  2. High-Purity Silicon Seeds for Silane Pyrolysis

    NASA Technical Reports Server (NTRS)

    Hsu, G. C.; Rohatgi, N. K.; Morrison, A.

    1985-01-01

    Seed particles for fluidized-bed production of silicon made by new contamination-free, economical method. In new method, large particles of semiconductor-grade silicon fired at each other by high-speed streams of gas and thereby break up into particles of suitable size for fluidized bed. No foreign materials introduced, and leaching unnecessary. Method used to feed fluidized-bed reactor for continuous production of high-purity silicon.

  3. Stacked Metal Silicide/Silicon Far-Infrared Detectors

    NASA Technical Reports Server (NTRS)

    Maserjian, Joseph

    1988-01-01

    Selective doping of silicon in proposed metal silicide/silicon Schottky-barrier infrared photodetector increases maximum detectable wavelength. Stacking layers to form multiple Schottky barriers increases quantum efficiency of detector. Detectors of new type enhance capabilities of far-infrared imaging arrays. Grows by molecular-beam epitaxy on silicon waferscontaining very-large-scale integrated circuits. Imaging arrays of detectors made in monolithic units with image-preprocessing circuitry.

  4. Model for the formation of silicon carbide from the pyrolysis of dichlorodimethylsilane in hydrogen. I - Silicon formation from chlorosilanes. II - Silicon carbide formation from silicon and methane

    NASA Technical Reports Server (NTRS)

    Cagliostro, Domenick E.; Riccitiello, Salvatore R.

    1993-01-01

    In the first part of this work, a model is developed for the deposition of silicon from the reduction of silicon tetrachloride with hydrogen in a tubular reactor at 700-1100 C, at atmospheric pressure. The model is based on gas chromatography of the volatile products of the reaction, followed by gravimetric analysis of total Si deposition on the tube. In the second part of this work, a model is developed for the case of SiC deposition from the pyrolysis of dichlorodimethylsilane in hydrogen under the same reactor conditions. The rate constants derived from a nonlinear regression analysis are reported.

  5. Chemical bonding in silicon-carbene complexes.

    PubMed

    Liu, Z

    2009-06-04

    The bonding situations in the newly synthesized silicon-carbene complexes with formulas L:SiCl4, L:(Cl)Si-Si(Cl):L, and L:Si=Si:L (where L: is an N-heterocyclic carbene), are reported using density functional theory at the BP86/TZ2P level. The bonding analysis clearly shows that the bonding situation in the silicon-carbene complexes cannot be described in terms of donor-acceptor interactions depicted in the Dewar-Chatt-Duncanson model. The energy decomposition analysis (EDA) shows that the electrostatic attraction plays an important or even dominant role for the Si-C(carbene) binding interactions in the silicon-carbene complexes. That the molecular orbitals of the silicon-carbene complexes are lower in energy than the parent orbitals of carbenes indicates that these complexes are better described as stabilized carbene complexes.

  6. Silicon Sheet Quality is Improved By Meniscus Control

    NASA Technical Reports Server (NTRS)

    Yates, D. A.; Hatch, A. E.; Goldsmith, J. M.

    1983-01-01

    Better quality silicon crystals for solar cells are possible with instrument that monitors position of meniscus as sheet of solid silicon is drawn from melt. Using information on meniscus height, instrument generates feedback signal to control melt temperature. Automatic control ensures more uniform silicon sheets.

  7. Diamond-Silicon Carbide Composite And Method For Preparation Thereof

    DOEpatents

    Qian, Jiang; Zhao, Yusheng

    2005-09-06

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5-8 GPa, T=1400K-2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.multidot.m.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  8. Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun

    Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

  9. Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

    DOE PAGES

    Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun; ...

    2017-09-11

    Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

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

    PubMed Central

    2012-01-01

    To study the influence of localized porous silicon regions on radiofrequency performances of passive devices, inductors were integrated on localized porous silicon regions, full porous silicon sheet, bulk silicon and glass substrates. In this work, a novel strong, resistant fluoropolymer mask is introduced to localize the porous silicon on the silicon wafer. Then, the quality factors and resonant frequencies obtained with the different substrates are presented. A first comparison is done between the performances of inductors integrated on same-thickness localized and full porous silicon sheet layers. The effect of the silicon regions in the decrease of performances of localized porous silicon is discussed. Then, the study shows that the localized porous silicon substrate significantly reduces losses in comparison with high-resistivity silicon or highly doped silicon bulks. These results are promising for the integration of both passive and active devices on the same silicon/porous silicon hybrid substrate. PMID:23009746

  11. Silicon Carbide Technology

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.

    2006-01-01

    Silicon carbide based semiconductor electronic devices and circuits are presently being developed for use in high-temperature, high-power, and high-radiation conditions under which conventional semiconductors cannot adequately perform. Silicon carbide's ability to function under such extreme conditions is expected to enable significant improvements to a far-ranging variety of applications and systems. These range from greatly improved high-voltage switching for energy savings in public electric power distribution and electric motor drives to more powerful microwave electronics for radar and communications to sensors and controls for cleaner-burning more fuel-efficient jet aircraft and automobile engines. In the particular area of power devices, theoretical appraisals have indicated that SiC power MOSFET's and diode rectifiers would operate over higher voltage and temperature ranges, have superior switching characteristics, and yet have die sizes nearly 20 times smaller than correspondingly rated silicon-based devices [8]. However, these tremendous theoretical advantages have yet to be widely realized in commercially available SiC devices, primarily owing to the fact that SiC's relatively immature crystal growth and device fabrication technologies are not yet sufficiently developed to the degree required for reliable incorporation into most electronic systems. This chapter briefly surveys the SiC semiconductor electronics technology. In particular, the differences (both good and bad) between SiC electronics technology and the well-known silicon VLSI technology are highlighted. Projected performance benefits of SiC electronics are highlighted for several large-scale applications. Key crystal growth and device-fabrication issues that presently limit the performance and capability of high-temperature and high-power SiC electronics are identified.

  12. Fabrication and Modification of Nanoporous Silicon Particles

    NASA Technical Reports Server (NTRS)

    Ferrari, Mauro; Liu, Xuewu

    2010-01-01

    Silicon-based nanoporous particles as biodegradable drug carriers are advantageous in permeation, controlled release, and targeting. The use of biodegradable nanoporous silicon and silicon dioxide, with proper surface treatments, allows sustained drug release within the target site over a period of days, or even weeks, due to selective surface coating. A variety of surface treatment protocols are available for silicon-based particles to be stabilized, functionalized, or modified as required. Coated polyethylene glycol (PEG) chains showed the effective depression of both plasma protein adsorption and cell attachment to the modified surfaces, as well as the advantage of long circulating. Porous silicon particles are micromachined by lithography. Compared to the synthesis route of the nanomaterials, the advantages include: (1) the capability to make different shapes, not only spherical particles but also square, rectangular, or ellipse cross sections, etc.; (2) the capability for very precise dimension control; (3) the capacity for porosity and pore profile control; and (4) allowance of complex surface modification. The particle patterns as small as 60 nm can be fabricated using the state-of-the-art photolithography. The pores in silicon can be fabricated by exposing the silicon in an HF/ethanol solution and then subjecting the pores to an electrical current. The size and shape of the pores inside silicon can be adjusted by the doping of the silicon, electrical current application, the composition of the electrolyte solution, and etching time. The surface of the silicon particles can be modified by many means to provide targeted delivery and on-site permanence for extended release. Multiple active agents can be co-loaded into the particles. Because the surface modification of particles can be done on wafers before the mechanical release, asymmetrical surface modification is feasible. Starting from silicon wafers, a treatment, such as KOH dipping or reactive ion

  13. Silicon nitride equation of state

    NASA Astrophysics Data System (ADS)

    Brown, Robert C.; Swaminathan, Pazhayannur K.

    2017-01-01

    This report presents the development of a global, multi-phase equation of state (EOS) for the ceramic silicon nitride (Si3N4).1 Structural forms include amorphous silicon nitride normally used as a thin film and three crystalline polymorphs. Crystalline phases include hexagonal α-Si3N4, hexagonal β-Si3N4, and the cubic spinel c-Si3N4. Decomposition at about 1900 °C results in a liquid silicon phase and gas phase products such as molecular nitrogen, atomic nitrogen, and atomic silicon. The silicon nitride EOS was developed using EOSPro which is a new and extended version of the PANDA II code. Both codes are valuable tools and have been used successfully for a variety of material classes. Both PANDA II and EOSPro can generate a tabular EOS that can be used in conjunction with hydrocodes. The paper describes the development efforts for the component solid phases and presents results obtained using the EOSPro phase transition model to investigate the solid-solid phase transitions in relation to the available shock data that have indicated a complex and slow time dependent phase change to the c-Si3N4 phase. Furthermore, the EOSPro mixture model is used to develop a model for the decomposition products; however, the need for a kinetic approach is suggested to combine with the single component solid models to simulate and further investigate the global phase coexistences.

  14. Quantum Properties of Dichroic Silicon Vacancies in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Nagy, Roland; Widmann, Matthias; Niethammer, Matthias; Dasari, Durga B. R.; Gerhardt, Ilja; Soykal, Öney O.; Radulaski, Marina; Ohshima, Takeshi; Vučković, Jelena; Son, Nguyen Tien; Ivanov, Ivan G.; Economou, Sophia E.; Bonato, Cristian; Lee, Sang-Yun; Wrachtrup, Jörg

    2018-03-01

    Although various defect centers have displayed promise as either quantum sensors, single photon emitters, or light-matter interfaces, the search for an ideal defect with multifunctional ability remains open. In this spirit, we study the dichroic silicon vacancies in silicon carbide that feature two well-distinguishable zero-phonon lines and analyze the quantum properties in their optical emission and spin control. We demonstrate that this center combines 40% optical emission into the zero-phonon lines showing the contrasting difference in optical properties with varying temperature and polarization, and a 100% increase in the fluorescence intensity upon the spin resonance, and long spin coherence time of their spin-3 /2 ground states up to 0.6 ms. These results single out this defect center as a promising system for spin-based quantum technologies.

  15. Thin Carbon Layers on Nanostructured Silicon-Properties and Applications

    NASA Astrophysics Data System (ADS)

    Angelescu, Anca; Kleps, Irina; Miu, Mihaela; Simion, Monica; Bragaru, Adina; Petrescu, Stefana; Paduraru, Crina; Raducanu, Aurelia

    Thin carbon layers such as silicon carbide (SiC) and diamond like carbon (DLC) layers on silicon, or on nanostructured silicon substrats were obtained by different methods. This paper is a review of our results in the areas of carbon layer microfabrication technologies and their properties related to different microsystem apllications. So, silicon membranes using a-SiC or DLC layers as etching mask, as well as silicon carbide membranes using a combined porous silicon — DLC structure were fabricated for sensor applications. A detailed evaluation of the field emission (FE) properties of these films was done to demonstrate their capability to be used in field emission devices. Carbon thin layers on nanostructured silicon samples were also investigated with respect to the living cell adhesion on these structures. The experiments indicate that the cell attachment on the surface of carbon coatings can be controlled by deposition parameters during the technological process.

  16. Application of optical processing for growth of silicon dioxide

    DOEpatents

    Sopori, B.L.

    1997-06-17

    A process for producing a silicon dioxide film on a surface of a silicon substrate is disclosed. The process comprises illuminating a silicon substrate in a substantially pure oxygen atmosphere with a broad spectrum of visible and infrared light at an optical power density of from about 3 watts/cm{sup 2} to about 6 watts/cm{sup 2} for a time period sufficient to produce a silicon dioxide film on the surface of the silicon substrate. An optimum optical power density is about 4 watts/cm{sup 2} for growth of a 100{angstrom}-300{angstrom} film at a resultant temperature of about 400 C. Deep level transient spectroscopy analysis detects no measurable impurities introduced into the silicon substrate during silicon oxide production and shows the interface state density at the SiO{sub 2}/Si interface to be very low. 1 fig.

  17. Organosilicon compounds. XVIII - Silicon-containing dianhydrides

    NASA Technical Reports Server (NTRS)

    Pratt, J. R.; Thames, S. F.

    1973-01-01

    Description of four new silicon-containing dianhydrides synthetized in an attempt to provide useful silicon-containing polyimide precursors. They were prepared by aqueous potassium permanganate-pyridine oxidations of corresponding tetramethyl intermediates to form tetracarboxylic acids, which were dehydrated to the dianhydrides.

  18. Silicon carbide semiconductor technology for high temperature and radiation environments

    NASA Technical Reports Server (NTRS)

    Matus, Lawrence G.

    1993-01-01

    Viewgraphs on silicon carbide semiconductor technology and its potential for enabling electronic devices to function in high temperature and high radiation environments are presented. Topics covered include silicon carbide; sublimation growth of 6H-SiC boules; SiC chemical vapor deposition reaction system; 6H silicon carbide p-n junction diode; silicon carbide MOSFET; and silicon carbide JFET radiation response.

  19. Method for forming silicon on a glass substrate

    DOEpatents

    McCarthy, Anthony M.

    1995-01-01

    A method by which single-crystal silicon microelectronics may be fabricated on glass substrates at unconventionally low temperatures. This is achieved by fabricating a thin film of silicon on glass and subsequently forming the doped components by a short wavelength (excimer) laser doping procedure and conventional patterning techniques. This method may include introducing a heavily boron doped etch stop layer on a silicon wafer using an excimer laser, which permits good control of the etch stop layer removal process. This method additionally includes dramatically reducing the remaining surface roughness of the silicon thin films after etching in the fabrication of silicon on insulator wafers by scanning an excimer laser across the surface of the silicon thin film causing surface melting, whereby the surface tension of the melt causes smoothing of the surface during recrystallization. Applications for this method include those requiring a transparent or insulating substrate, such as display manufacturing. Other applications include sensors, actuators, optoelectronics, radiation hard and high temperature electronics.

  20. Method for forming silicon on a glass substrate

    DOEpatents

    McCarthy, A.M.

    1995-03-07

    A method by which single-crystal silicon microelectronics may be fabricated on glass substrates at unconventionally low temperatures. This is achieved by fabricating a thin film of silicon on glass and subsequently forming the doped components by a short wavelength (excimer) laser doping procedure and conventional patterning techniques. This method may include introducing a heavily boron doped etch stop layer on a silicon wafer using an excimer laser, which permits good control of the etch stop layer removal process. This method additionally includes dramatically reducing the remaining surface roughness of the silicon thin films after etching in the fabrication of silicon on insulator wafers by scanning an excimer laser across the surface of the silicon thin film causing surface melting, whereby the surface tension of the melt causes smoothing of the surface during recrystallization. Applications for this method include those requiring a transparent or insulating substrate, such as display manufacturing. Other applications include sensors, actuators, optoelectronics, radiation hard and high temperature electronics. 15 figs.

  1. Micropatterned arrays of porous silicon: toward sensory biointerfaces.

    PubMed

    Flavel, Benjamin S; Sweetman, Martin J; Shearer, Cameron J; Shapter, Joseph G; Voelcker, Nicolas H

    2011-07-01

    We describe the fabrication of arrays of porous silicon spots by means of photolithography where a positive photoresist serves as a mask during the anodization process. In particular, photoluminescent arrays and porous silicon spots suitable for further chemical modification and the attachment of human cells were created. The produced arrays of porous silicon were chemically modified by means of a thermal hydrosilylation reaction that facilitated immobilization of the fluorescent dye lissamine, and alternatively, the cell adhesion peptide arginine-glycine-aspartic acid-serine. The latter modification enabled the selective attachment of human lens epithelial cells on the peptide functionalized regions of the patterns. This type of surface patterning, using etched porous silicon arrays functionalized with biological recognition elements, presents a new format of interfacing porous silicon with mammalian cells. Porous silicon arrays with photoluminescent properties produced by this patterning strategy also have potential applications as platforms for in situ monitoring of cell behavior.

  2. Copper-assisted, anti-reflection etching of silicon surfaces

    DOEpatents

    Toor, Fatima; Branz, Howard

    2014-08-26

    A method (300) for etching a silicon surface (116) to reduce reflectivity. The method (300) includes electroless deposition of copper nanoparticles about 20 nanometers in size on the silicon surface (116), with a particle-to-particle spacing of 3 to 8 nanometers. The method (300) includes positioning (310) the substrate (112) with a silicon surface (116) into a vessel (122). The vessel (122) is filled (340) with a volume of an etching solution (124) so as to cover the silicon surface (116). The etching solution (124) includes an oxidant-etchant solution (146), e.g., an aqueous solution of hydrofluoric acid and hydrogen peroxide. The silicon surface (116) is etched (350) by agitating the etching solution (124) with, for example, ultrasonic agitation, and the etching may include heating (360) the etching solution (124) and directing light (365) onto the silicon surface (116). During the etching, copper nanoparticles enhance or drive the etching process.

  3. Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Holden, S. C.; Fleming, J. R.

    1978-01-01

    Fabrication of a prototype large capacity multiple blade slurry saw is considered. Design of the bladehead which will tension up to 1000 blades, and cut a 45 cm long silicon ingot as large as 12 cm in diameter is given. The large blade tensioning force of 270,000 kg is applied through two bolts acting on a pair of scissor toggles, significantly reducing operator set-up time. Tests with an upside-down cutting technique resulted in 100% wafering yields and the highest wafer accuracy yet experienced with MS slicing. Variations in oil and abrasives resulted only in degraded slicing results. A technique of continuous abrasive slurry separation to remove silicon debris is described.

  4. Weakly modulated silicon-dioxide-cladding gratings for silicon waveguide Fabry-Pérot cavities.

    PubMed

    Grote, Richard R; Driscoll, Jeffrey B; Biris, Claudiu G; Panoiu, Nicolae C; Osgood, Richard M

    2011-12-19

    We show by theory and experiment that silicon-dioxide-cladding gratings for Fabry-Pérot cavities on silicon-on-insulator channel ("wire") waveguides provide a low-refractive-index perturbation, which is required for several important integrated photonics components. The underlying refractive index perturbation of these gratings is significantly weaker than that of analogous silicon gratings, leading to finer control of the coupling coefficient κ. Our Fabry-Pérot cavities are designed using the transfer-matrix method (TMM) in conjunction with the finite element method (FEM) for calculating the effective index of each waveguide section. Device parameters such as coupling coefficient, κ, Bragg mirror stop band, Bragg mirror reflectivity, and quality factor Q are examined via TMM modeling. Devices are fabricated with representative values of distributed Bragg reflector lengths, cavity lengths, and propagation losses. The measured transmission spectra show excellent agreement with the FEM/TMM calculations.

  5. Develop Silicone Encapsulation Systems for Terrestrial Silicon Solar Arrays

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A cost effective encapsulant system was identified and a silicone acrylic cover material containing a durable ultraviolet screening agent was prepared. The effectiveness of the cover material in protecting photo-oxidatively sensitive polymers was demonstrated.

  6. Methods and apparatuses for manufacturing monocrystalline cast silicon and monocrystalline cast silicon bodies for photovoltaics

    DOEpatents

    Stoddard, Nathan G [Gettysburg, PA

    2011-11-01

    Methods and apparatuses are provided for casting silicon for photovoltaic cells and other applications. With such methods and apparatuses, a cast body of monocrystalline silicon may be formed that is free of, or substantially free of, radially-distributed impurities and defects and having at least two dimensions that are each at least about 35 cm is provided.

  7. Silicon microring resonators

    NASA Astrophysics Data System (ADS)

    Tan, Ying; Dai, Daoxin

    2018-05-01

    Silicon microring resonators (MRRs) are very popular for many applications because of the advantages of footprint compactness, easy scalability, and functional versatility. Ultra-compact silicon MRRs with box-like spectral responses are realized with a very large free-spectral range (FSR) by introducing bent directional couplers. The measured box-like spectral response has an FSR of >30 nm. The permanent wavelength-alignment techniques for MRRs are also presented, including the laser-induced local-oxidation technique as well as the local-etching technique. With these techniques, one can control finely the permanent wavelength shift, which is also large enough to compensate the random wavelength variation due to the random fabrication errors.

  8. High damage tolerance of electrochemically lithiated silicon

    PubMed Central

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; Wang, Haoran; Tao, Siyu; Yang, Avery; Liu, Yang; Beng Chew, Huck; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-01-01

    Mechanical degradation and resultant capacity fade in high-capacity electrode materials critically hinder their use in high-performance rechargeable batteries. Despite tremendous efforts devoted to the study of the electro–chemo–mechanical behaviours of high-capacity electrode materials, their fracture properties and mechanisms remain largely unknown. Here we report a nanomechanical study on the damage tolerance of electrochemically lithiated silicon. Our in situ transmission electron microscopy experiments reveal a striking contrast of brittle fracture in pristine silicon versus ductile tensile deformation in fully lithiated silicon. Quantitative fracture toughness measurements by nanoindentation show a rapid brittle-to-ductile transition of fracture as the lithium-to-silicon molar ratio is increased to above 1.5. Molecular dynamics simulations elucidate the mechanistic underpinnings of the brittle-to-ductile transition governed by atomic bonding and lithiation-induced toughening. Our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries. PMID:26400671

  9. High damage tolerance of electrochemically lithiated silicon

    NASA Astrophysics Data System (ADS)

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; Wang, Haoran; Tao, Siyu; Yang, Avery; Liu, Yang; Beng Chew, Huck; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-09-01

    Mechanical degradation and resultant capacity fade in high-capacity electrode materials critically hinder their use in high-performance rechargeable batteries. Despite tremendous efforts devoted to the study of the electro-chemo-mechanical behaviours of high-capacity electrode materials, their fracture properties and mechanisms remain largely unknown. Here we report a nanomechanical study on the damage tolerance of electrochemically lithiated silicon. Our in situ transmission electron microscopy experiments reveal a striking contrast of brittle fracture in pristine silicon versus ductile tensile deformation in fully lithiated silicon. Quantitative fracture toughness measurements by nanoindentation show a rapid brittle-to-ductile transition of fracture as the lithium-to-silicon molar ratio is increased to above 1.5. Molecular dynamics simulations elucidate the mechanistic underpinnings of the brittle-to-ductile transition governed by atomic bonding and lithiation-induced toughening. Our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries.

  10. Tailored porous silicon microparticles: fabrication and properties

    PubMed Central

    Chiappini, Ciro; Tasciotti, Ennio; Fakhoury, Jean R.; Fine, Daniel; Pullan, Lee; Wang, Young-Chung; Fu, Lianfeng

    2010-01-01

    The use of mesoporous silicon particles for drug delivery has been widely explored thanks to their biodegradability and biocompatibility. The ability to tailor the physicochemical properties of porous silicon at the micro and nano scale confers versatility to this material. We present a method for the fabrication of highly reproducible, monodisperse mesoporous silicon particles with controlled physical characteristics through electrochemical etch of patterned silicon trenches. We tailored particle size in the micrometer range and pore size in the nanometer range, shape from tubular to discoidal to hemispherical, and porosity from 46% to over 80%. In addition, we correlated the properties of the porous matrix with the loading of model nanoparticles (Q-dots) and observed their three-dimensional arrangement within the matrix by transmission electron microscopy tomography. The methods developed in this study provide effective means to fabricate mesoporous silicon particles according to the principles of rational design for therapeutic vectors and to characterize the distribution of nanoparticles within the porous matrix PMID:20162656

  11. Dissolution of bulk specimens of silicon nitride

    NASA Technical Reports Server (NTRS)

    Davis, W. F.; Merkle, E. J.

    1981-01-01

    An accurate chemical characterization of silicon nitride has become important in connection with current efforts to incorporate components of this material into advanced heat engines. However, there are problems concerning a chemical analysis of bulk silicon nitride. Current analytical methods require the pulverization of bulk specimens. A pulverization procedure making use of grinding media, on the other hand, will introduce contaminants. A description is given of a dissolution procedure which overcomes these difficulties. It has been found that up to at least 0.6 g solid pieces of various samples of hot pressed and reaction bonded silicon nitride can be decomposed in a mixture of 3 mL hydrofluoric acid and 1 mL nitric acid overnight at 150 C in a Parr bomb. High-purity silicon nitride is completely soluble in nitric acid after treatment in the bomb. Following decomposition, silicon and hydrofluoric acid are volatilized and insoluble fluorides are converted to a soluble form.

  12. High damage tolerance of electrochemically lithiated silicon

    DOE PAGES

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; ...

    2015-09-24

    Mechanical degradation and resultant capacity fade in high-capacity electrode materials critically hinder their use in high-performance rechargeable batteries. Despite tremendous efforts devoted to the study of the electro–chemo–mechanical behaviours of high-capacity electrode materials, their fracture properties and mechanisms remain largely unknown. In this paper, we report a nanomechanical study on the damage tolerance of electrochemically lithiated silicon. Our in situ transmission electron microscopy experiments reveal a striking contrast of brittle fracture in pristine silicon versus ductile tensile deformation in fully lithiated silicon. Quantitative fracture toughness measurements by nanoindentation show a rapid brittle-to-ductile transition of fracture as the lithium-to-silicon molar ratiomore » is increased to above 1.5. Molecular dynamics simulations elucidate the mechanistic underpinnings of the brittle-to-ductile transition governed by atomic bonding and lithiation-induced toughening. Finally, our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries.« less

  13. Development of a statistically proven injection molding method for reaction bonded silicon nitride, sintering reaction bonded silicon nitride, and sintered silicon nitride

    NASA Astrophysics Data System (ADS)

    Steiner, Matthias

    A statistically proven, series injection molding technique for ceramic components was developed for the construction of engines and gas turbines. The flow behavior of silicon injection-molding materials was characterized and improved. Hot-isostatic-pressing reaction bonded silicon nitride (HIPRBSN) was developed. A nondestructive component evaluation method was developed. An injection molding line for HIPRBSN engine components precombustion chamber, flame spreader, and valve guide was developed. This line allows the production of small series for engine tests.

  14. LSSA (Low-cost Silicon Solar Array) project

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Methods are explored for economically generating electrical power to meet future requirements. The Low-Cost Silicon Solar Array Project (LSSA) was established to reduce the price of solar arrays by improving manufacturing technology, adapting mass production techniques, and promoting user acceptance. The new manufacturing technology includes the consideration of new silicon refinement processes, silicon sheet growth techniques, encapsulants, and automated assembly production being developed under contract by industries and universities.

  15. Complications of cataract surgery in eyes filled with silicone oil.

    PubMed

    Kanclerz, Piotr; Grzybowski, Andrzej; Schwartz, Stephen G; Lipowski, Paweł

    2018-03-01

    The aim of the study was to evaluate complications of cataract surgery in eyes filled with silicone oil. This retrospective, noncomparative, consecutive case series analyzed medical files of patients with eyes filled with silicone oil undergoing cataract surgery. Phacoemulsification with posterior chamber intraocular lens implantation was conducted with or without concurrent silicone oil removal. In this study, 121 eyes of 120 patients were included. In 32 eyes (26.4%) with evident silicone oil microemulsification or silicone oil-associated open-angle glaucoma, silicone oil was removed prior to phacoemulsification through a pars plana incision and no cases of posterior capsular rupture occurred during the subsequent cataract surgery. In the remaining 89 eyes, phacoemulsification was performed with silicone oil in the vitreous cavity. In these eyes, the rate of posterior capsular rupture was 9/89 (10.1%) and the rate of silicone oil migration into the anterior chamber through an apparently intact posterior capsule was 5/89 (5.6%). In 94 eyes (77.7%), an intraocular lens was inserted into the capsular bag, in 3 eyes (2.5%) into the sulcus, and in 1 eye (0.8%) a transscleral suturing was performed. In this series, complications related to the silicone oil were not uncommon during cataract surgery. In the majority of patients without evident silicone oil microemulsification or silicone oil-associated open-angle glaucoma, cataract surgery and posterior chamber intraocular lens implantation were performed while leaving the silicone oil in place.

  16. Modified Silicone-Rubber Tooling For Molding Composite Parts

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Snoha, John J.; Weiser, Erik S.

    1995-01-01

    Reduced-thermal-expansion, reduced-bulk-modulus silicone rubber for use in mold tooling made by incorporating silica powder into silicone rubber. Pressure exerted by thermal expansion reduced even further by allowing air bubbles to remain in silicone rubber instead of deaerating it. Bubbles reduce bulk modulus of material.

  17. Solid structures with bioorganic films on silicon

    NASA Astrophysics Data System (ADS)

    Tutov, E. A.

    2012-06-01

    The electrophysical parameters of ovalbumin/silicon and propolis/silicon heterostructures are studied using impedance spectroscopy and high-frequency capacitance-voltage characteristics under water vapor sorption conditions.

  18. Amphiphilic silicone architectures via anaerobic thiol-ene chemistry.

    PubMed

    Keddie, Daniel J; Grande, John B; Gonzaga, Ferdinand; Brook, Michael A; Dargaville, Tim R

    2011-11-18

    Despite broad application, few silicone-based surfactants of known structure or, therefore, surfactancy have been prepared because of an absence of selective routes and instability of silicones to acid and base. Herein the synthesis of a library of explicit silicone-poly(ethylene glycol) (PEG) materials is reported. Pure silicone fragments were generated by the B(C(6)F(5))(3)-catalyzed condensation of alkoxysilanes and vinyl-functionalized hydrosilanes. The resulting pure products were coupled to thiol-terminated PEG materials using photogenerated radicals under anaerobic conditions.

  19. Model for Transport and Luminescence in Porous Silicon

    NASA Astrophysics Data System (ADS)

    John, George C.; Singh, Vijay A.

    1996-03-01

    A unified model for explaining the transport and luminescence properties of porous silicon has remained elusive(G.C.John and V.A.Singh, Phys. Rep. (in press)). The conductivity of porous silicon has been reported to increase exponentially with temperature(J.J.Mares et al.), Appl. Phys. Lett. 63, 180 (1993). We report additional observations of such instances. This Berthelot type behavior is ascribed to tunneling of carriers across a vibrating barrier. We hypothesize that the non-radiative recombination in porous silicon is governed by a similar mechanism. Based on this assumption, we show that the temperature and pressure dependence of luminescence in porous silicon can be convincingly explained. We present a unified phenomenological model which can account for a range of observations in porous silicon.

  20. Electrochemistry of Silicon: Instrumentation, Science, Materials and Applications

    NASA Astrophysics Data System (ADS)

    Lehmann, Volker

    2002-04-01

    Silicon has been and will most probably continue to be the dominant material in semiconductor technology. Although the defect-free silicon single crystal is one of the best understood systems in materails science, its electrochemistry to many people is still a kind of "alchemy". This view is partly due to the interdisciplinary aspects of the topic: Physics meets chemistry at the silicon-electrolyte interface. This book gives a comprehensive overview of this important aspect of silicon technology as well as examples of applications ranging from photonic crystals to biochips. It will serve materials scientists as well as engineers involved in silicon technology as a quick reference with its more than 150 technical tables and diagrams and ca. 1000 references cited for easy access of the original literature.

  1. Silicon Web Process Development. [for solar cell fabrication

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    Silicon dendritic web, ribbon form of silicon and capable of fabrication into solar cells with greater than 15% AMl conversion efficiency, was produced from the melt without die shaping. Improvements were made both in the width of the web ribbons grown and in the techniques to replenish the liquid silicon as it is transformed to web. Through means of improved thermal shielding stress was reduced sufficiently so that web crystals nearly 4.5 cm wide were grown. The development of two subsystems, a silicon feeder and a melt level sensor, necessary to achieve an operational melt replenishment system, is described. A gas flow management technique is discussed and a laser reflection method to sense and control the melt level as silicon is replenished is examined.

  2. Role of the primary silicon particle on the dry sliding wear of hypereutectic aluminium-silicon alloy A390

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Moo; Kang, Suk-Bong; Yoon, Sang-Chul

    1999-07-01

    The wear behavior of hypereutectic aluminium-silicon alloy A390 was investigated using a pin-on-disc wear machine under dry sliding conditions. The wear tests were performed within a load range of 10 to 300N at a constant sliding velocity of 0.5 m/sec. The microstructural and compositional changes that took place during wear were characterized by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analysis (EDXA) system. Based on the metallographic observations the role of the primary silicon particles was suggested. In a low pressure region, primary silicon particles supported the applied load and wear occurred mainly in the matrix. Thus the wear loss did not show much variation with the applied load. In the mid-load range, primary silicon particles did not yet fracture and thus supported the applied load in part. Transition from oxidative to metallic wear occurs mainly in the matrix and the increase of wear loss becomes sharper than that in a low pressure region. In the high pressure region, the fractures of primary silicon Particles occurred and wear loss increased sharply.

  3. Double stabilization of nanocrystalline silicon: a bonus from solvent

    NASA Astrophysics Data System (ADS)

    Kolyagin, Y. G.; Zakharov, V. N.; Yatsenko, A. V.; Paseshnichenko, K. A.; Savilov, S. V.; Aslanov, L. A.

    2016-01-01

    Double stabilization of the silicon nanocrystals was observed for the first time by 29Si and 13C MAS NMR spectroscopy. The role of solvent, 1,2-dimethoxyethane (glyme), in formation and stabilization of silicon nanocrystals as well as mechanism of modification of the surface of silicon nanocrystals by nitrogen-heterocyclic carbene (NHC) was studied in this research. It was shown that silicon nanocrystals were stabilized by the products of cleavage of the C-O bonds in ethers and similar compounds. The fact of stabilization of silicon nanoparticles with NHC ligands in glyme was experimentally detected. It was demonstrated that MAS NMR spectroscopy is rather informative for study of the surface of silicon nanoparticles but it needs very pure samples.

  4. Doping of silicon with carbon during laser ablation process

    NASA Astrophysics Data System (ADS)

    Račiukaitis, G.; Brikas, M.; Kazlauskienė, V.; Miškinis, J.

    2006-12-01

    The effect of laser ablation on properties of remaining material in silicon was investigated. It was found that laser cutting of wafers in the air induced the doping of silicon with carbon. The effect was more distinct when using higher laser power or UV radiation. Carbon ions created bonds with silicon atoms in the depth of the material. Formation of the silicon carbide type bonds was confirmed by SIMS, XPS and AES measurements. Modeling of the carbon diffusion to clarify its depth profile in silicon was performed. Photochemical reactions of such type changed the structure of material and could be the reason of the reduced machining quality. The controlled atmosphere was applied to prevent carbonization of silicon during laser cutting.

  5. Self-organized, effective medium black silicon antireflection structures for silicon optics in the mid-infrared

    NASA Astrophysics Data System (ADS)

    Steglich, Martin; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2016-09-01

    Thanks to its high quality and low cost, silicon is the material of choice for optical devices operating in the mid-infrared (MIR; 2 μm to 6 μm wavelength). Unfortunately in this spectral region, the refractive index is comparably high (about 3.5) and leads to severe reflection losses of about 30% per interface. In this work, we demonstrate that self-organized, statistical Black Silicon structures, fabricated by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE), can be used to effectively suppress interface reflection. More importantly, it is shown that antireflection can be achieved in an image-preserving, non-scattering way. This enables Black Silicon antireflection structures (ARS) for imaging applications in the MIR. It is demonstrated that specular transmittances of 97% can be easily achieved on both flat and curved substrates, e.g. lenses. Moreover, by a combined optical and morphological analysis of a multitude of different Black Silicon ARS, an effective medium criterion for the examined structures is derived that can also be used as a design rule for maximizing sample transmittance in a desired wavelength range. In addition, we show that the mechanical durability of the structures can be greatly enhanced by coating with hard dielectric materials like diamond-like carbon (DLC), hence enabling practical applications. Finally, the distinct advantages of statistical Black Silicon ARS over conventional AR layer stacks are discussed: simple applicability to topological substrates, absence of thermal stress and cost-effectiveness.

  6. Urethane/Silicone Adhesives for Bonding Flexing Metal Parts

    NASA Technical Reports Server (NTRS)

    Edwards, Paul D.

    2004-01-01

    Adhesives that are blends of commercially available urethane and silicone adhesives have been found to be useful for bonding metal parts that flex somewhat during use. These urethane/silicone adhesives are formulated for the specific metal parts to be bonded. The bonds formed by these adhesives have peel and shear strengths greater than those of bonds formed by double-sided tapes and by other adhesives, including epoxies and neat silicones. In addition, unlike the bonds formed by epoxies, the bonds formed by these adhesives retain flexibility. In the initial application for which the urethane/silicone adhesives were devised, there was a need to bond spring rings, which provide longitudinal rigidity for inflatable satellite booms, with the blades that provide the booms axial strength. The problem was to make the bonds withstand the stresses, associated with differences in curvature between the bonded parts, that arose when the booms were deflated and the springs were compressed. In experiments using single adhesives (that is, not the urethane/ silicone blends), the bonds were broken and, in each experiment, it was found that the adhesive bonded well with either the ring or with the blade, but not both. After numerous experiments, the adhesive that bonded best with the rings and the adhesive that bonded best with the blades were identified. These adhesives were then blended and, as expected, the blend bonded well with both the rings and the blades. The two adhesives are Kalex (or equivalent) high-shear-strength urethane and Dow Corning 732 (or equivalent) silicone. The nominal mixture ratio is 5 volume parts of the urethane per 1 volume part of the silicone. Increasing the proportion of silicone makes the bond weaker but more flexible, and decreasing the proportion of silicone makes the bond stronger but more brittle. The urethane/silicone blend must be prepared and used quickly because of the limited working time of the urethane: The precursor of the urethane

  7. Lithium ion batteries based on nanoporous silicon

    DOEpatents

    Tolbert, Sarah H.; Nemanick, Eric J.; Kang, Chris Byung-Hwa

    2015-09-22

    A lithium ion battery that incorporates an anode formed from a Group IV semiconductor material such as porous silicon is disclosed. The battery includes a cathode, and an anode comprising porous silicon. In some embodiments, the anode is present in the form of a nanowire, a film, or a powder, the porous silicon having a pore diameters within the range between 2 nm and 100 nm and an average wall thickness of within the range between 1 nm and 100 nm. The lithium ion battery further includes, in some embodiments, a non-aqueous lithium containing electrolyte. Lithium ion batteries incorporating a porous silicon anode demonstrate have high, stable lithium alloying capacity over many cycles.

  8. Microdistribution of oxygen in silicon

    NASA Technical Reports Server (NTRS)

    Murgai, A.; Chi, J. Y.; Gatos, H. C.

    1980-01-01

    The microdistribution of oxygen in Czochralskii-grown, p-type silicon crystals was determined by using the SEM in the EBIC mode in conjunction with spreading resistance measurements. When the conductivity remained p-type, bands of contrast were observed in the EBIC image which corresponded to maxima in resistivity. When at the oxygen concentration maxima the oxygen donor concentration exceeded the p-type dopant concentration, an inversion of the conductivity occurred. It resulted in the formation of p-n junctions in a striated configuration and the local inversion of the EBIC image contrast. By heat-treating silicon at 1000 C prior to the activation of oxygen donors, some silicon-oxygen micro-precipitates were observed in the EBIC image within the striated oxygen concentration maxima.

  9. Deposition of hydrogenated silicon clusters for efficient epitaxial growth.

    PubMed

    Le, Ha-Linh Thi; Jardali, Fatme; Vach, Holger

    2018-06-13

    Epitaxial silicon thin films grown from the deposition of plasma-born hydrogenated silicon nanoparticles using plasma-enhanced chemical vapor deposition have widely been investigated due to their potential applications in photovoltaic and nanoelectronic device technologies. However, the optimal experimental conditions and the underlying growth mechanisms leading to the high-speed epitaxial growth of thin silicon films from hydrogenated silicon nanoparticles remain far from being understood. In the present work, extensive molecular dynamics simulations were performed to study the epitaxial growth of silicon thin films resulting from the deposition of plasma-born hydrogenated silicon clusters at low substrate temperatures under realistic reactor conditions. There is strong evidence that a temporary phase transition of the substrate area around the cluster impact site to the liquid state is necessary for the epitaxial growth to take place. We predict further that a non-normal incidence angle for the cluster impact significantly facilitates the epitaxial growth of thin crystalline silicon films.

  10. Thermometry of Silicon Nanoparticles

    NASA Astrophysics Data System (ADS)

    Mecklenburg, Matthew; Zutter, Brian; Regan, B. C.

    2018-01-01

    Current thermometry techniques lack the spatial resolution required to see the temperature gradients in typical, highly scaled modern transistors. As a step toward addressing this problem, we measure the temperature dependence of the volume plasmon energy in silicon nanoparticles from room temperature to 1250 °C , using a chip-style heating sample holder in a scanning transmission electron microscope (STEM) equipped with electron energy loss spectroscopy (EELS). The plasmon energy changes as expected for an electron gas subject to the thermal expansion of silicon. Reversing this reasoning, we find that measurements of the plasmon energy provide an independent measure of the nanoparticle temperature consistent with that of the heater chip's macroscopic, dual-function heater-and-thermometer to within the 5% accuracy of the thermometer's calibration. Thus, silicon has the potential to provide its own high-spatial-resolution thermometric readout signal via measurements of its volume plasmon energy. Furthermore, nanoparticles can, in general, serve as convenient nanothermometers for in situ electron-microscopy experiments.

  11. The electrophotonic silicon biosensor

    NASA Astrophysics Data System (ADS)

    Juan-Colás, José; Parkin, Alison; Dunn, Katherine E.; Scullion, Mark G.; Krauss, Thomas F.; Johnson, Steven D.

    2016-09-01

    The emergence of personalized and stratified medicine requires label-free, low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high-sensitivity analysis with scalable, low-cost manufacturing, but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomarkers. Our electrophotonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical control enables site-selective immobilization of different biomolecules on individual microrings within a sensor array. The combination of photonic and electrochemical characterization also provides additional quantitative information and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the microscale.

  12. Plasmonic and silicon spherical nanoparticle antireflective coatings

    NASA Astrophysics Data System (ADS)

    Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

    2016-03-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

  13. Plasmonic and silicon spherical nanoparticle antireflective coatings

    PubMed Central

    Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

    2016-01-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes. PMID:26926602

  14. An analog silicon retina with multichip configuration.

    PubMed

    Kameda, Seiji; Yagi, Tetsuya

    2006-01-01

    The neuromorphic silicon retina is a novel analog very large scale integrated circuit that emulates the structure and the function of the retinal neuronal circuit. We fabricated a neuromorphic silicon retina, in which sample/hold circuits were embedded to generate fluctuation-suppressed outputs in the previous study [1]. The applications of this silicon retina, however, are limited because of a low spatial resolution and computational variability. In this paper, we have fabricated a multichip silicon retina in which the functional network circuits are divided into two chips: the photoreceptor network chip (P chip) and the horizontal cell network chip (H chip). The output images of the P chip are transferred to the H chip with analog voltages through the line-parallel transfer bus. The sample/hold circuits embedded in the P and H chips compensate for the pattern noise generated on the circuits, including the analog communication pathway. Using the multichip silicon retina together with an off-chip differential amplifier, spatial filtering of the image with an odd- and an even-symmetric orientation selective receptive fields was carried out in real time. The analog data transfer method in the present multichip silicon retina is useful to design analog neuromorphic multichip systems that mimic the hierarchical structure of neuronal networks in the visual system.

  15. Intravitreal properties of porous silicon photonic crystals

    PubMed Central

    Cheng, L; Anglin, E; Cunin, F; Kim, D; Sailor, M J; Falkenstein, I; Tammewar, A; Freeman, W R

    2009-01-01

    Aim To determine the suitability of porous silicon photonic crystals for intraocular drug-delivery. Methods A rugate structure was electrochemically etched into a highly doped p-type silicon substrate to create a porous silicon film that was subsequently removed and ultrasonically fractured into particles. To stabilise the particles in aqueous media, the silicon particles were modified by surface alkylation (using thermal hydrosilylation) or by thermal oxidation. Unmodified particles, hydrosilylated particles and oxidised particles were injected into rabbit vitreous. The stability and toxicity of each type of particle were studied by indirect ophthalmoscopy, biomicroscopy, tonometry, electroretinography (ERG) and histology. Results No toxicity was observed with any type of the particles during a period of >4 months. Surface alkylation led to dramatically increased intravitreal stability and slow degradation. The estimated vitreous half-life increased from 1 week (fresh particles) to 5 weeks (oxidised particles) and to 16 weeks (hydrosilylated particles). Conclusion The porous silicon photonic crystals showed good biocompatibility and may be used as an intraocular drug-delivery system. The intravitreal injectable porous silicon photonic crystals may be engineered to host a variety of therapeutics and achieve controlled drug release over long periods of time to treat chronic vitreoretinal diseases. PMID:18441177

  16. Thiolated silicone oil: Synthesis, gelling and mucoadhesive properties

    PubMed Central

    Partenhauser, Alexandra; Laffleur, Flavia; Rohrer, Julia; Bernkop-Schnürch, Andreas

    2015-01-01

    The aim of this study was the development of novel thiolated silicone oils and their evaluation with regard to gelling and mucoadhesive properties. A thiol coupling of 220 ± 14 and 127 ± 33 μmol/g polymer for 3-mercaptopropionic acid (MPA)- and cysteine-coupled silicone oil was determined, respectively. The dynamic viscosity of MPA–silicone raised significantly (p < 0.000001) after oxidation with iodine to a maximum of 523-fold within 1 h. During tensile studies, MPA–silicone showed both the highest results for total work of adhesion (TWA) and maximum detachment force (MDF) with a 3.8- and 3.4-fold increase, respectively, compared to the control. As far as the residence time on small intestinal mucosa is concerned, both silicone conjugates were detectable in almost the same quantities for up to 8 h with 56.9 ± 3.3 and 47.8 ± 8.9% of the initially applied conjugated silicone oil. Thiolated silicone oils can be regarded superior in comparison to commonly used silicone oils due to a prolonged retention time in the small intestine as site of action. Gelling and mucoadhesive features are advantageous for antiflatulent as well as mucoprotective biomaterials. Thus, these novel thiomers seem promising for an upgrade of currently available products for the treatment of dyspepsia, reflux oesophagitis and even inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease. PMID:25660565

  17. Multibit Polycristalline Silicon-Oxide-Silicon Nitride-Oxide-Silicon Memory Cells with High Density Designed Utilizing a Separated Control Gate

    NASA Astrophysics Data System (ADS)

    Rok Kim, Kyeong; You, Joo Hyung; Dal Kwack, Kae; Kim, Tae Whan

    2010-10-01

    Unique multibit NAND polycrystalline silicon-oxide-silicon nitride-oxide-silicon (SONOS) memory cells utilizing a separated control gate (SCG) were designed to increase memory density. The proposed NAND SONOS memory device based on a SCG structure was operated as two bits, resulting in an increase in the storage density of the NVM devices in comparison with conventional single-bit memories. The electrical properties of the SONOS memory cells with a SCG were investigated to clarify the charging effects in the SONOS memory cells. When the program voltage was supplied to each gate of the NAND SONOS flash memory cells, the electrons were trapped in the nitride region of the oxide-nitride-oxide layer under the gate to supply the program voltage. The electrons were accumulated without affecting the other gate during the programming operation, indicating the absence of cross-talk between two trap charge regions. It is expected that the inference effect will be suppressed by the lower program voltage than the program voltage of the conventional NAND flash memory. The simulation results indicate that the proposed unique NAND SONOS memory cells with a SCG can be used to increase memory density.

  18. Silicon coupled with plasmon nanocavities generates bright visible hot luminescence

    NASA Astrophysics Data System (ADS)

    Cho, Chang-Hee; Aspetti, Carlos O.; Park, Joohee; Agarwal, Ritesh

    2013-04-01

    To address the limitations in device speed and performance in silicon-based electronics, there have been extensive studies on silicon optoelectronics with a view to achieving ultrafast optical data processing. The biggest challenge has been to develop an efficient silicon-based light source, because the indirect bandgap of silicon gives rise to extremely low emission efficiencies. Although light emission in quantum-confined silicon at sub-10 nm length scales has been demonstrated, there are difficulties in integrating quantum structures with conventional electronics. It is desirable to develop new concepts to obtain emission from silicon at length scales compatible with current electronic devices (20-100 nm), which therefore do not utilize quantum-confinement effects. Here, we demonstrate an entirely new method to achieve bright visible light emission in `bulk-sized' silicon coupled with plasmon nanocavities at room temperature, from non-thermalized carrier recombination. The highly enhanced emission (internal quantum efficiency of >1%) in plasmonic silicon, together with its size compatibility with current silicon electronics, provides new avenues for developing monolithically integrated light sources on conventional microchips.

  19. Method and apparatus for producing high purity silicon

    DOEpatents

    Olson, Jerry M.

    1984-01-01

    A method for producing high purity silicon includes forming a copper silie alloy and positioning the alloy within an enclosure. A filament member is also placed within the enclosure opposite the alloy. The enclosure is then filled with a chemical vapor transport gas adapted for transporting silicon. Finally, both the filament member and the alloy are heated to temperatures sufficient to cause the gas to react with silicon at the alloy surface and deposit the reacted silicon on the filament member. In addition, an apparatus for carrying out this method is also disclosed.

  20. Method and apparatus for producing high purity silicon

    DOEpatents

    Olson, J.M.

    1983-05-27

    A method for producing high purity silicon includes forming a copper silicide alloy and positioning the alloy within an enclosure. A filament member is also placed within the enclosure opposite the alloy. The enclosure is then filled with a chemical vapor transport gas adapted for transporting silicon. Finally, both the filament member and the alloy are heated to temperatures sufficient to cause the gas to react with silicon at the alloy surface and deposit the reacted silicon on the filament member. In addition, an apparatus for carrying out this method is also disclosed.

  1. Feasibility study of silicon nitride regenerators

    NASA Technical Reports Server (NTRS)

    Fucinari, C. A.; Rao, V. D. N.

    1979-01-01

    The feasibility of silicon nitride as a regenerator matrix material for applications requiring inlet temperatures above 1000 C is examined. The present generation oxide ceramics are used as a reference to examine silicon nitride from a material characteristics, manufacturing, thermal stress and aerothermodynamic viewpoint.

  2. Nanostructured silicon anodes for lithium ion rechargeable batteries.

    PubMed

    Teki, Ranganath; Datta, Moni K; Krishnan, Rahul; Parker, Thomas C; Lu, Toh-Ming; Kumta, Prashant N; Koratkar, Nikhil

    2009-10-01

    Rechargeable lithium ion batteries are integral to today's information-rich, mobile society. Currently they are one of the most popular types of battery used in portable electronics because of their high energy density and flexible design. Despite their increasing use at the present time, there is great continued commercial interest in developing new and improved electrode materials for lithium ion batteries that would lead to dramatically higher energy capacity and longer cycle life. Silicon is one of the most promising anode materials because it has the highest known theoretical charge capacity and is the second most abundant element on earth. However, silicon anodes have limited applications because of the huge volume change associated with the insertion and extraction of lithium. This causes cracking and pulverization of the anode, which leads to a loss of electrical contact and eventual fading of capacity. Nanostructured silicon anodes, as compared to the previously tested silicon film anodes, can help overcome the above issues. As arrays of silicon nanowires or nanorods, which help accommodate the volume changes, or as nanoscale compliant layers, which increase the stress resilience of silicon films, nanoengineered silicon anodes show potential to enable a new generation of lithium ion batteries with significantly higher reversible charge capacity and longer cycle life.

  3. Second-harmonic generation in substoichiometric silicon nitride layers

    NASA Astrophysics Data System (ADS)

    Pecora, Emanuele; Capretti, Antonio; Miano, Giovanni; Dal Negro, Luca

    2013-03-01

    Harmonic generation in optical circuits offers the possibility to integrate wavelength converters, light amplifiers, lasers, and multiple optical signal processing devices with electronic components. Bulk silicon has a negligible second-order nonlinear optical susceptibility owing to its crystal centrosymmetry. Silicon nitride has its place in the microelectronic industry as an insulator and chemical barrier. In this work, we propose to take advantage of silicon excess in silicon nitride to increase the Second Harmonic Generation (SHG) efficiency. Thin films have been grown by reactive magnetron sputtering and their nonlinear optical properties have been studied by femtosecond pumping over a wide range of excitation wavelengths, silicon nitride stoichiometry and thermal processes. We demonstrate SHG in the visible range (375 - 450 nm) using a tunable 150 fs Ti:sapphire laser, and we optimize the SH emission at a silicon excess of 46 at.% demonstrating a maximum SHG efficiency of 4x10-6 in optimized films. Polarization properties, generation efficiency, and the second order nonlinear optical susceptibility are measured for all the investigated samples and discussed in terms of an effective theoretical model. Our findings show that the large nonlinear optical response demonstrated in optimized Si-rich silicon nitride materials can be utilized for the engineering of nonlinear optical functions and devices on a Si chip.

  4. Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

    DOEpatents

    Stevenson, David T.; Troup, Robert L.

    1985-01-01

    Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide.

  5. Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

    DOEpatents

    Stevenson, D.T.; Troup, R.L.

    1985-01-01

    Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide. 1 fig.

  6. Silicon ball grid array chip carrier

    DOEpatents

    Palmer, David W.; Gassman, Richard A.; Chu, Dahwey

    2000-01-01

    A ball-grid-array integrated circuit (IC) chip carrier formed from a silicon substrate is disclosed. The silicon ball-grid-array chip carrier is of particular use with ICs having peripheral bond pads which can be reconfigured to a ball-grid-array. The use of a semiconductor substrate such as silicon for forming the ball-grid-array chip carrier allows the chip carrier to be fabricated on an IC process line with, at least in part, standard IC processes. Additionally, the silicon chip carrier can include components such as transistors, resistors, capacitors, inductors and sensors to form a "smart" chip carrier which can provide added functionality and testability to one or more ICs mounted on the chip carrier. Types of functionality that can be provided on the "smart" chip carrier include boundary-scan cells, built-in test structures, signal conditioning circuitry, power conditioning circuitry, and a reconfiguration capability. The "smart" chip carrier can also be used to form specialized or application-specific ICs (ASICs) from conventional ICs. Types of sensors that can be included on the silicon ball-grid-array chip carrier include temperature sensors, pressure sensors, stress sensors, inertia or acceleration sensors, and/or chemical sensors. These sensors can be fabricated by IC processes and can include microelectromechanical (MEM) devices.

  7. Compact and low power operation optical switch using silicon-germanium/silicon hetero-structure waveguide.

    PubMed

    Sekiguchi, Shigeaki; Kurahashi, Teruo; Zhu, Lei; Kawaguchi, Kenichi; Morito, Ken

    2012-04-09

    We proposed a silicon-based optical switch with a carrier-plasma-induced phase shifter which employs a silicon-germanium (SiGe) / silicon (Si) hetero-structure in the waveguide core. A type-I hetero-interface formed by SiGe and Si is expected to confine carriers effectively in the SiGe waveguide core. The fabricated Mach-Zehnder optical switch shows a low switching power of only 1.53 mW with a compact phase shifter length of 250 μm. The switching time of the optical switch is less than 4.6 ns for the case of a square waveform driving condition, and 1 ns for the case of a pre-emphasis electric driving condition. These results show that our proposed SiGe/Si waveguide structure holds promise for active devices with compact size and low operation power.

  8. Silicone absorption of elastomeric closures--an accelerated study.

    PubMed

    Degrazio, F L; Hlobik, T; Vaughan, S

    1998-01-01

    There is a trend in the parenteral industry to move from the use of elastomeric closures which are washed, siliconized, dried and sterilized in-house at the pharmaceutical manufacturers' site to pre-prepared closures purchased from the closure supplier. This preparation can consist of washing to reduce particle-load and bioburden, siliconization, placement in ready-to-sterilize bags and may eventually extend to sterilization by steam autoclave or gamma irradiation. Since silicone oil lubrication is critical to the processability/machinability of closures, research was designed to investigate this phenomenon in closures prepared using the Westar RS (Ready-to-Sterilize) process. This paper presents the data gathered in a study of the characteristic of silicone absorption into elastomeric closures under accelerated conditions. Variables such as silicone viscosity, rubber formulation, effect of sterilization and others are considered.

  9. Silicon photonics: some remaining challenges

    NASA Astrophysics Data System (ADS)

    Reed, G. T.; Topley, R.; Khokhar, A. Z.; Thompson, D. J.; Stanković, S.; Reynolds, S.; Chen, X.; Soper, N.; Mitchell, C. J.; Hu, Y.; Shen, L.; Martinez-Jimenez, G.; Healy, N.; Mailis, S.; Peacock, A. C.; Nedeljkovic, M.; Gardes, F. Y.; Soler Penades, J.; Alonso-Ramos, C.; Ortega-Monux, A.; Wanguemert-Perez, G.; Molina-Fernandez, I.; Cheben, P.; Mashanovich, G. Z.

    2016-03-01

    This paper discusses some of the remaining challenges for silicon photonics, and how we at Southampton University have approached some of them. Despite phenomenal advances in the field of Silicon Photonics, there are a number of areas that still require development. For short to medium reach applications, there is a need to improve the power consumption of photonic circuits such that inter-chip, and perhaps intra-chip applications are viable. This means that yet smaller devices are required as well as thermally stable devices, and multiple wavelength channels. In turn this demands smaller, more efficient modulators, athermal circuits, and improved wavelength division multiplexers. The debate continues as to whether on-chip lasers are necessary for all applications, but an efficient low cost laser would benefit many applications. Multi-layer photonics offers the possibility of increasing the complexity and effectiveness of a given area of chip real estate, but it is a demanding challenge. Low cost packaging (in particular, passive alignment of fibre to waveguide), and effective wafer scale testing strategies, are also essential for mass market applications. Whilst solutions to these challenges would enhance most applications, a derivative technology is emerging, that of Mid Infra-Red (MIR) silicon photonics. This field will build on existing developments, but will require key enhancements to facilitate functionality at longer wavelengths. In common with mainstream silicon photonics, significant developments have been made, but there is still much left to do. Here we summarise some of our recent work towards wafer scale testing, passive alignment, multiplexing, and MIR silicon photonics technology.

  10. What controls silicon isotope fractionation during dissolution of diatom opal?

    NASA Astrophysics Data System (ADS)

    Wetzel, F.; de Souza, G. F.; Reynolds, B. C.

    2014-04-01

    The silicon isotope composition of opal frustules from photosynthesising diatoms is a promising tool for studying past changes in the marine silicon cycle, and indirectly that of carbon. Dissolution of this opal may be accompanied by silicon isotope fractionation that could disturb the pristine silicon isotope composition of diatom opal acquired in the surface ocean. It has previously been shown that dissolution of fresh and sediment trap diatom opal in seawater does fractionate silicon isotopes. However, as the mechanism of silicon isotope fractionation remained elusive, it is uncertain whether opal dissolution in general is associated with silicon isotope fractionation considering that opal chemistry and surface properties are spatially and temporally (i.e. opal of different age) diverse. In this study we dissolved sediment core diatom opal in 5 mM NaOH and found that this process is not associated with significant silicon isotope fractionation. Since no variability of the isotope effect was observed over a wide range of dissolution rates, we can rule out the suggestion that back-reactions had a significant influence on the net isotope effect. Similarly, we did not observe an impact of temperature, specific surface area, or degree of undersaturation on silicon isotope partitioning during dissolution, such that these can most likely also be ruled out as controlling factors. We discuss the potential impacts of the chemical composition of the dissolution medium and age of diatom opal on silicon isotope fractionation during dissolution. It appears most likely that the controlling mechanism of silicon isotope fractionation during dissolution is related to the reactivity, or potentially, aluminium content of the opal. Such a dependency would imply that silicon isotope fractionation during dissolution of diatom opal is spatially and temporally variable. However, since the isotope effects during dissolution are small, the silicon isotope composition of diatom opal

  11. Smoother Scribing of Silicon Wafers

    NASA Technical Reports Server (NTRS)

    Danyluk, S.

    1986-01-01

    Proposed new tool used to scribe silicon wafers into chips more smoothly than before. New scriber produces surface that appears ductile. Scribed groove cuts have relatively smooth walls. Scriber consists of diamond pyramid point on rigid shaft. Ethanol flows through shaft and around point, like ink in ballpoint pen. Ethanol has significantly different effect for scribing silicon than water, used in conventional diamond scribers.

  12. Silicone nanocomposite coatings for fabrics

    NASA Technical Reports Server (NTRS)

    Lee, Stein S. (Inventor); Ou, Runqing (Inventor); Eberts, Kenneth (Inventor); Singhal, Amit (Inventor)

    2011-01-01

    A silicone based coating for fabrics utilizing dual nanocomposite fillers providing enhanced mechanical and thermal properties to the silicone base. The first filler includes nanoclusters of polydimethylsiloxane (PDMS) and a metal oxide and a second filler of exfoliated clay nanoparticles. The coating is particularly suitable for inflatable fabrics used in several space, military, and consumer applications, including airbags, parachutes, rafts, boat sails, and inflatable shelters.

  13. Hybrid Silicon Photonic Integration using Quantum Well Intermixing

    NASA Astrophysics Data System (ADS)

    Jain, Siddharth R.

    With the push for faster data transfer across all domains of telecommunication, optical interconnects are transitioning into shorter range applications such as in data centers and personal computing. Silicon photonics, with its economic advantages of leveraging well-established silicon manufacturing facilities, is considered the most promising approach to further scale down the cost and size of optical interconnects for chip-to-chip communication. Intrinsic properties of silicon however limit its ability to generate and modulate light, both of which are key to realizing on-chip optical data transfer. The hybrid silicon approach directly addresses this problem by using molecularly bonded III-V epitaxial layers on silicon for optical gain and absorption. This technology includes direct transfer of III-V wafer to a pre-patterned silicon-on-insulator wafer. Several discrete devices for light generation, modulation, amplification and detection have already been demonstrated on this platform. As in the case of electronics, multiple photonic elements can be integrated on a single chip to improve performance and functionality. However, scalable photonic integration requires the ability to control the bandgap for individual devices along with design changes to simplify fabrication. In the research presented here, quantum well intermixing is used as a technique to define multiple bandgaps for integration on the hybrid silicon platform. Implantation enhanced disordering is used to generate four bandgaps spread over 120+ nm. By combining these selectively intermixed III-V layers with pre-defined gratings and waveguides on silicon, we fabricate distributed feedback, distributed Bragg reflector, Fabry-Perot and mode-locked lasers along with photodetectors, electro-absorption modulators and other test structures, all on a single chip. We demonstrate a broadband laser source with continuous-wave operational lasers over a 200 nm bandwidth. Some of these lasers are integrated with

  14. Dip coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Heaps, J. D.; Maciolek, R. B.; Zook, J. D.; Harrison, W. B.; Scott, M. W.; Hendrickson, G.; Wolner, H. A.; Nelson, L. D.; Schuller, T. L.; Peterson, A. A.

    1976-01-01

    The technical and economic feasibility of producing solar cell quality sheet silicon by dip-coating one surface of carbonized ceramic substrates with a thin layer of large grain polycrystalline silicon was investigated. The dip-coating methods studied were directed toward a minimum cost process with the ultimate objective of producing solar cells with a conversion efficiency of 10% or greater. The technique shows excellent promise for low cost, labor-saving, scale-up potentialities and would provide an end product of sheet silicon with a rigid and strong supportive backing. An experimental dip-coating facility was designed and constructed, several substrates were successfully dip-coated with areas as large as 25 sq cm and thicknesses of 12 micron to 250 micron. There appears to be no serious limitation on the area of a substrate that could be coated. Of the various substrate materials dip-coated, mullite appears to best satisfy the requirement of the program. An inexpensive process was developed for producing mullite in the desired geometry.

  15. 21 CFR 878.4025 - Silicone sheeting.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Silicone sheeting. 878.4025 Section 878.4025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...) Identification. Silicone sheeting is intended for use in the management of closed hyperproliferative...

  16. Limits on silicon nanoelectronics for terascale integration.

    PubMed

    Meindl, J D; Chen, Q; Davis, J A

    2001-09-14

    Throughout the past four decades, silicon semiconductor technology has advanced at exponential rates in both performance and productivity. Concerns have been raised, however, that the limits of silicon technology may soon be reached. Analysis of fundamental, material, device, circuit, and system limits reveals that silicon technology has an enormous remaining potential to achieve terascale integration (TSI) of more than 1 trillion transistors per chip. Such massive-scale integration is feasible assuming the development and economical mass production of double-gate metal-oxide-semiconductor field effect transistors with gate oxide thickness of about 1 nanometer, silicon channel thickness of about 3 nanometers, and channel length of about 10 nanometers. The development of interconnecting wires for these transistors presents a major challenge to the achievement of nanoelectronics for TSI.

  17. Silicon photonics for high-performance interconnection networks

    NASA Astrophysics Data System (ADS)

    Biberman, Aleksandr

    2011-12-01

    We assert in the course of this work that silicon photonics has the potential to be a key disruptive technology in computing and communication industries. The enduring pursuit of performance gains in computing, combined with stringent power constraints, has fostered the ever-growing computational parallelism associated with chip multiprocessors, memory systems, high-performance computing systems, and data centers. Sustaining these parallelism growths introduces unique challenges for on- and off-chip communications, shifting the focus toward novel and fundamentally different communication approaches. This work showcases that chip-scale photonic interconnection networks, enabled by high-performance silicon photonic devices, enable unprecedented bandwidth scalability with reduced power consumption. We demonstrate that the silicon photonic platforms have already produced all the high-performance photonic devices required to realize these types of networks. Through extensive empirical characterization in much of this work, we demonstrate such feasibility of waveguides, modulators, switches, and photodetectors. We also demonstrate systems that simultaneously combine many functionalities to achieve more complex building blocks. Furthermore, we leverage the unique properties of available silicon photonic materials to create novel silicon photonic devices, subsystems, network topologies, and architectures to enable unprecedented performance of these photonic interconnection networks and computing systems. We show that the advantages of photonic interconnection networks extend far beyond the chip, offering advanced communication environments for memory systems, high-performance computing systems, and data centers. Furthermore, we explore the immense potential of all-optical functionalities implemented using parametric processing in the silicon platform, demonstrating unique methods that have the ability to revolutionize computation and communication. Silicon photonics

  18. Silicide/Silicon Hetero-Junction Structure for Thermoelectric Applications.

    PubMed

    Jun, Dongsuk; Kim, Soojung; Choi, Wonchul; Kim, Junsoo; Zyung, Taehyoung; Jang, Moongyu

    2015-10-01

    We fabricated silicide/silicon hetero-junction structured thermoelectric device by CMOS process for the reduction of thermal conductivity with the scatterings of phonons at silicide/silicon interfaces. Electrical conductivities, Seebeck coefficients, power factors, and temperature differences are evaluated using the steady state analysis method. Platinum silicide/silicon multilayered structure showed an enhanced Seebeck coefficient and power factor characteristics, which was considered for p-leg element. Also, erbium silicide/silicon structure showed an enhanced Seebeck coefficient, which was considered for an n-leg element. Silicide/silicon multilayered structure is promising for thermoelectric applications by reducing thermal conductivity with an enhanced Seebeck coefficient. However, because of the high thermal conductivity of the silicon packing during thermal gradient is not a problem any temperature difference. Therefore, requires more testing and analysis in order to overcome this problem. Thermoelectric generators are devices that based on the Seebeck effect, convert temperature differences into electrical energy. Although thermoelectric phenomena have been used for heating and cooling applications quite extensively, it is only in recent years that interest has increased in energy generation.

  19. Deposition method for producing silicon carbide high-temperature semiconductors

    DOEpatents

    Hsu, George C.; Rohatgi, Naresh K.

    1987-01-01

    An improved deposition method for producing silicon carbide high-temperature semiconductor material comprising placing a semiconductor substrate composed of silicon carbide in a fluidized bed silicon carbide deposition reactor, fluidizing the bed particles by hydrogen gas in a mildly bubbling mode through a gas distributor and heating the substrate at temperatures around 1200.degree.-1500.degree. C. thereby depositing a layer of silicon carbide on the semiconductor substrate.

  20. A probabilistic analysis of silicon cost

    NASA Technical Reports Server (NTRS)

    Reiter, L. J.

    1983-01-01

    Silicon materials costs represent both a cost driver and an area where improvement can be made in the manufacture of photovoltaic modules. The cost from three processes for the production of low-cost silicon being developed under the U.S. Department of Energy's (DOE) National Photovoltaic Program is analyzed. The approach is based on probabilistic inputs and makes use of two models developed at the Jet Propulsion Laboratory: SIMRAND (SIMulation of Research ANd Development) and IPEG (Improved Price Estimating Guidelines). The approach, assumptions, and limitations are detailed along with a verification of the cost analyses methodology. Results, presented in the form of cumulative probability distributions for silicon cost, indicate that there is a 55% chance of reaching the DOE target of $16/kg for silicon material. This is a technically achievable cost based on expert forecasts of the results of ongoing research and development and do not imply any market prices for a given year.

  1. Core-shell silicon nanowire solar cells

    PubMed Central

    Adachi, M. M.; Anantram, M. P.; Karim, K. S.

    2013-01-01

    Silicon nanowires can enhance broadband optical absorption and reduce radial carrier collection distances in solar cell devices. Arrays of disordered nanowires grown by vapor-liquid-solid method are attractive because they can be grown on low-cost substrates such as glass, and are large area compatible. Here, we experimentally demonstrate that an array of disordered silicon nanowires surrounded by a thin transparent conductive oxide has both low diffuse and specular reflection with total values as low as < 4% over a broad wavelength range of 400 nm < λ < 650 nm. These anti-reflective properties together with enhanced infrared absorption in the core-shell nanowire facilitates enhancement in external quantum efficiency using two different active shell materials: amorphous silicon and nanocrystalline silicon. As a result, the core-shell nanowire device exhibits a short-circuit current enhancement of 15% with an amorphous Si shell and 26% with a nanocrystalline Si shell compared to their corresponding planar devices. PMID:23529071

  2. Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

    DOE PAGES

    Shi, Jianwei; Boccard, Mathieu; Holman, Zachary

    2016-07-19

    The dehydrogenation of intrinsic hydrogenated amorphous silicon (a-Si:H) at temperatures above approximately 300°C degrades its ability to passivate silicon wafer surfaces. This limits the temperature of post-passivation processing steps during the fabrication of advanced silicon heterojunction or silicon-based tandem solar cells. We demonstrate that a hydrogen plasma can rehydrogenate intrinsic a-Si:H passivation layers that have been dehydrogenated by annealing. The hydrogen plasma treatment fully restores the effective carrier lifetime to several milliseconds in textured crystalline siliconwafers coated with 8-nm-thick intrinsic a-Si:H layers after annealing at temperatures of up to 450°C. Plasma-initiated rehydrogenation also translates to complete solar cells: A silicon heterojunction solar cell subjected to annealing at 450°C (following intrinsic a-Si:H deposition) had an open-circuit voltage of less than 600 mV, but an identical cell that received hydrogen plasma treatment reached a voltagemore » of over 710 mV and an efficiency of over 19%.« less

  3. Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shi, Jianwei; Boccard, Mathieu; Holman, Zachary

    The dehydrogenation of intrinsic hydrogenated amorphous silicon (a-Si:H) at temperatures above approximately 300°C degrades its ability to passivate silicon wafer surfaces. This limits the temperature of post-passivation processing steps during the fabrication of advanced silicon heterojunction or silicon-based tandem solar cells. We demonstrate that a hydrogen plasma can rehydrogenate intrinsic a-Si:H passivation layers that have been dehydrogenated by annealing. The hydrogen plasma treatment fully restores the effective carrier lifetime to several milliseconds in textured crystalline siliconwafers coated with 8-nm-thick intrinsic a-Si:H layers after annealing at temperatures of up to 450°C. Plasma-initiated rehydrogenation also translates to complete solar cells: A silicon heterojunction solar cell subjected to annealing at 450°C (following intrinsic a-Si:H deposition) had an open-circuit voltage of less than 600 mV, but an identical cell that received hydrogen plasma treatment reached a voltagemore » of over 710 mV and an efficiency of over 19%.« less

  4. Size dependence of nanoscale wear of silicon carbide

    Treesearch

    Chaiyapat Tangpatjaroen; David Grierson; Steve Shannon; Joseph E. Jakes; Izabela Szlufarska

    2017-01-01

    Nanoscale, single-asperity wear of single-crystal silicon carbide (sc- SiC) and nanocrystalline silicon carbide (nc-SiC) is investigated using single-crystal diamond nanoindenter tips and nanocrystalline diamond atomic force microscopy (AFM) tips under dry conditions, and the wear behavior is compared to that of single-crystal silicon with both thin and thick native...

  5. Equilibrium water and solute uptake in silicone hydrogels.

    PubMed

    Liu, D E; Dursch, T J; Oh, Y; Bregante, D T; Chan, S Y; Radke, C J

    2015-05-01

    Equilibrium water content of and solute partitioning in silicone hydrogels (SiHys) are investigated using gravimetric analysis, fluorescence confocal laser-scanning microscopy (FCLSM), and back extraction with UV/Vis-absorption spectrophotometry. Synthesized silicone hydrogels consist of silicone monomer, hydrophilic monomer, cross-linking agent, and triblock-copolymer macromer used as an amphiphilic compatibilizer to prevent macrophase separation. In all cases, immiscibility of the silicone and hydrophilic polymers results in microphase-separated morphologies. To investigate solute uptake in each of the SiHy microphases, equilibrium partition coefficients are obtained for two hydrophilic solutes (i.e., theophylline and caffeine dissolved in aqueous phosphate-buffered saline) and two oleophilic solutes (i.e., Nile Red and Bodipy Green dissolved in silicone oil), respectively. Measured water contents and aqueous-solute partition coefficients increase linearly with increasing solvent-free hydrophilic-polymer volume fraction. Conversely, oleophilic-solute partition coefficients decrease linearly with rising solvent-free hydrophilic-polymer volume fraction (i.e., decreasing hydrophobic silicone-polymer fraction). We quantitatively predict equilibrium SiHy water and solute uptake assuming that water and aqueous solutes reside only in hydrophilic microdomains, whereas oleophilic solutes partition predominately into silicone microdomains. Predicted water contents and solute partition coefficients are in excellent agreement with experiment. Our new procedure permits a priori estimation of SiHy water contents and solute partition coefficients based solely on properties of silicone and hydrophilic homopolymer hydrogels, eliminating the need for further mixed-polymer-hydrogel experiments. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Silicone-containing aqueous polymer dispersions with hybrid particle structure.

    PubMed

    Kozakiewicz, Janusz; Ofat, Izabela; Trzaskowska, Joanna

    2015-09-01

    In this paper the synthesis, characterization and application of silicone-containing aqueous polymer dispersions (APD) with hybrid particle structure are reviewed based on available literature data. Advantages of synthesis of dispersions with hybrid particle structure over blending of individual dispersions are pointed out. Three main processes leading to silicone-containing hybrid APD are identified and described in detail: (1) emulsion polymerization of organic unsaturated monomers in aqueous dispersions of silicone polymers or copolymers, (2) emulsion copolymerization of unsaturated organic monomers with alkoxysilanes or polysiloxanes with unsaturated functionality and (3) emulsion polymerization of alkoxysilanes (in particular with unsaturated functionality) and/or cyclic siloxanes in organic polymer dispersions. The effect of various factors on the properties of such hybrid APD and films as well as on hybrid particles composition and morphology is presented. It is shown that core-shell morphology where silicones constitute either the core or the shell is predominant in hybrid particles. Main applications of silicone-containing hybrid APD and related hybrid particles are reviewed including (1) coatings which show specific surface properties such as enhanced water repellency or antisoiling or antigraffiti properties due to migration of silicone to the surface, and (2) impact modifiers for thermoplastics and thermosets. Other processes in which silicone-containing particles with hybrid structure can be obtained (miniemulsion polymerization, polymerization in non-aqueous media, hybridization of organic polymer and polysiloxane, emulsion polymerization of silicone monomers in silicone polymer dispersions and physical methods) are also discussed. Prospects for further developments in the area of silicone-containing hybrid APD and related hybrid particles are presented. Copyright © 2015. Published by Elsevier B.V.

  7. Biocompatibility evaluation of 3 facial silicone elastomers.

    PubMed

    França, Diurianne Caroline Campos; de Castro, Alvimar Lima; Soubhia, Ana Maria Pires; Tucci, Renata; de Aguiar, Sandra Maria Herondina Coelho Ávila; Goiato, Marcelo Coelho

    2011-05-01

    The failure of facial prostheses is caused by limitations in the properties of existing materials, especially the biocompatibility. This study aimed to evaluate the biocompatibility of maxillofacial silicones in subcutaneous tissue of rats. Thirty Wistar rats received subcutaneous implants of 3 maxillofacial silicone elastomers (LIM 6050, MDX 4-4210, and industrial Silastic 732 RTV). A histomorphometric evaluation was conducted to analyze the biocompatibility of the implants. Eight areas of 60.11 mm(2) from the surgical pieces were analyzed. Mesenchymal cells, eosinophils, and foreign-body giant cells were counted. Data were submitted to analysis of variance and Tukey test. Initially, all implanted materials exhibited an acceptable tissue inflammatory response, with tissue reactions varying from light to moderate. Afterward, a fibrous capsule around the silicone was observed. The silicones used in the current study presented biocompatibility and can be used for implantation in both medical and dental areas. Their prosthetic indication is conditioned to their physical properties. Solid silicone is easier to adapt and does not suffer apparent modifications inside the tissues.

  8. Water-assisted pulsed Er:YAG laser interaction with silicon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, Jaehun; Ki, Hyungson, E-mail: hski@unist.ac.kr

    2015-07-07

    Silicon is virtually transparent to the Er:YAG laser with a wavelength of 2.94 μm. In this study, we report that moderately doped silicon (1–10 Ω cm) can be processed by a pulsed Er:YAG laser with a pulse duration of 350 μs and a peak laser intensity of 1.7 × 10{sup 5} W/cm{sup 2} by applying a thin water layer on top of silicon as a light absorbing medium. In this way, water is heated first by strongly absorbing the laser energy and then heats up the silicon wafer indirectly. As the silicon temperature rises, the free carrier concentration and therefore the absorption coefficient of silicon willmore » increase significantly, which may enable the silicon to get directly processed by the Er:YAG laser when the water is vaporized completely. We also believe that the change in surface morphology after melting could contribute to the increase in the laser beam absorptance. It was observed that 525 nm-thick p-type wafer specimens were fully penetrated after 15 laser pulses were irradiated. Bright yellow flames were observed during the process, which indicates that the silicon surface reached the melting point.« less

  9. Flexible integration of free-standing nanowires into silicon photonics.

    PubMed

    Chen, Bigeng; Wu, Hao; Xin, Chenguang; Dai, Daoxin; Tong, Limin

    2017-06-14

    Silicon photonics has been developed successfully with a top-down fabrication technique to enable large-scale photonic integrated circuits with high reproducibility, but is limited intrinsically by the material capability for active or nonlinear applications. On the other hand, free-standing nanowires synthesized via a bottom-up growth present great material diversity and structural uniformity, but precisely assembling free-standing nanowires for on-demand photonic functionality remains a great challenge. Here we report hybrid integration of free-standing nanowires into silicon photonics with high flexibility by coupling free-standing nanowires onto target silicon waveguides that are simultaneously used for precise positioning. Coupling efficiency between a free-standing nanowire and a silicon waveguide is up to ~97% in the telecommunication band. A hybrid nonlinear-free-standing nanowires-silicon waveguides Mach-Zehnder interferometer and a racetrack resonator for significantly enhanced optical modulation are experimentally demonstrated, as well as hybrid active-free-standing nanowires-silicon waveguides circuits for light generation. These results suggest an alternative approach to flexible multifunctional on-chip nanophotonic devices.Precisely assembling free-standing nanowires for on-demand photonic functionality remains a challenge. Here, Chen et al. integrate free-standing nanowires into silicon waveguides and show all-optical modulation and light generation on silicon photonic chips.

  10. Flat-plate solar array project. Volume 2: Silicon material

    NASA Technical Reports Server (NTRS)

    Lutwack, R.

    1986-01-01

    The goal of the Silicon Material Task, a part of the Flat Plate Solar Array (FSA) Project, was to develop and demonstate the technology for the low cost production of silicon of suitable purity to be used as the basic material for the manufacture of terrestrial photovoltaic solar cells. Summarized are 11 different processes for the production of silicon that were investigated and developed to varying extent by industrial, university, and Government researchers. The silane production section of the Union Carbide Corp. (UCC) silane process was developed completely in this program. Coupled with Siemens-type chemical vapor deposition reactors, the process was carried through the pilot stage. The overall UCC process involves the conversion of metallurgical-grade silicon to silane followed by decomposition of the silane to purified silicon. The other process developments are described to varying extents. Studies are reported on the effects of impurities in silicon on both silicon-material properties and on solar cell performance. These studies on the effects of impurities yielded extensive information and models for relating specific elemental concentrations to levels of deleterious effects.

  11. Flat-plate solar array project. Volume 2: Silicon material

    NASA Astrophysics Data System (ADS)

    Lutwack, R.

    1986-10-01

    The goal of the Silicon Material Task, a part of the Flat Plate Solar Array (FSA) Project, was to develop and demonstate the technology for the low cost production of silicon of suitable purity to be used as the basic material for the manufacture of terrestrial photovoltaic solar cells. Summarized are 11 different processes for the production of silicon that were investigated and developed to varying extent by industrial, university, and Government researchers. The silane production section of the Union Carbide Corp. (UCC) silane process was developed completely in this program. Coupled with Siemens-type chemical vapor deposition reactors, the process was carried through the pilot stage. The overall UCC process involves the conversion of metallurgical-grade silicon to silane followed by decomposition of the silane to purified silicon. The other process developments are described to varying extents. Studies are reported on the effects of impurities in silicon on both silicon-material properties and on solar cell performance. These studies on the effects of impurities yielded extensive information and models for relating specific elemental concentrations to levels of deleterious effects.

  12. 21 CFR 878.4025 - Silicone sheeting.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Silicone sheeting. 878.4025 Section 878.4025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4025 Silicone sheeting. (a...

  13. 21 CFR 878.4025 - Silicone sheeting.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Silicone sheeting. 878.4025 Section 878.4025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4025 Silicone sheeting. (a...

  14. 21 CFR 878.4025 - Silicone sheeting.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Silicone sheeting. 878.4025 Section 878.4025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4025 Silicone sheeting. (a...

  15. 21 CFR 878.4025 - Silicone sheeting.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Silicone sheeting. 878.4025 Section 878.4025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4025 Silicone sheeting. (a...

  16. Electrochemical thinning of silicon

    DOEpatents

    Medernach, J.W.

    1994-01-11

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR). 14 figures.

  17. Electrochemical thinning of silicon

    DOEpatents

    Medernach, John W.

    1994-01-01

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR).

  18. Wetting of silicone oil onto a cell-seeded substrate

    NASA Astrophysics Data System (ADS)

    Lu, Yongjie; Chan, Yau Kei; Chao, Youchuang; Shum, Ho Cheung

    2017-11-01

    Wetting behavior of solid substrates in three-phase systems containing two immiscible liquids are widely studied. There exist many three-phase systems in biological environments, such as droplet-based microfluidics or tamponade of silicone oil for eye surgery. However, few studies focus on wetting behavior of biological surfaces with cells. Here we investigate wetting of silicone oil onto cell-seeded PMMA sheet immersed in water. Using a simple parallel-plate cell, we show the effect of cell density, viscosity of silicone oil, morphology of silicone oil drops and interfacial tension on the wetting phenomenon. The dynamics of wetting is also observed by squeezing silicone oil drop using two parallel plates. Experimental results are explained based on disjoining pressure which is dependent on the interaction of biological surfaces and liquid used. These findings are useful for explaining emulsification of silicone oil in ophthalmological applications.

  19. Formation of silicon carbide by laser ablation in graphene oxide-N-methyl-2-pyrrolidone suspension on silicon surface

    NASA Astrophysics Data System (ADS)

    Jaleh, Babak; Ghasemi, Samaneh; Torkamany, Mohammad Javad; Salehzadeh, Sadegh; Maleki, Farahnaz

    2018-01-01

    Laser ablation of a silicon wafer in graphene oxide-N-methyl-2-pyrrolidone (GO-NMP) suspension was carried out with a pulsed Nd:YAG laser (pulse duration = 250 ns, wavelength = 1064 nm). The surface of silicon wafer before and after laser ablation was studied using optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The results showed that the ablation of silicon surface in liquid by pulsed laser was done by the process of melt expulsion under the influence of the confined plasma-induced pressure or shock wave trapped between the silicon wafer and the liquid. The X-ray diffraction‌ (XRD) pattern of Si wafer after laser ablation showed that 4H-SiC layer is formed on its surface. The formation of the above layer was also confirmed by Raman spectroscopy, and X-ray photoelectron spectroscopy‌ (XPS), as well as EDX was utilized. The reflectance of samples decreased with increasing pulse energy. Therefore, the morphological alteration and the formation of SiC layer at high energy increase absorption intensity in the UV‌-vis regions. Theoretical calculations confirm that the formation of silicon carbide from graphene oxide and silicon wafer is considerably endothermic. Development of new methods for increasing the reflectance without causing harmful effects is still an important issue for crystalline Si solar cells. By using the method described in this paper, the optical properties of solar cells can be improved.

  20. Linguine sign in musculoskeletal imaging: calf silicone implant rupture.

    PubMed

    Duryea, Dennis; Petscavage-Thomas, Jonelle; Frauenhoffer, Elizabeth E; Walker, Eric A

    2015-08-01

    Imaging findings of breast silicone implant rupture are well described in the literature. On MRI, the linguine sign indicates intracapsular rupture, while the presence of silicone particles outside the fibrous capsule indicates extracapsular rupture. The linguine sign is described as the thin, wavy hypodense wall of the implant within the hyperintense silicone on T2-weighted images indicative of rupture of the implant within the naturally formed fibrous capsule. Hyperintense T2 signal outside of the fibrous capsule is indicative of an extracapsular rupture with silicone granuloma formation. We present a rare case of a patient with a silicone calf implant rupture and discuss the MRI findings associated with this condition.

  1. Feasibility of using mixtures of silicone elastomers and silicone oils to model the mechanical behaviour of biological tissues

    PubMed Central

    Ahmadzadeh, S Mohammad Hassan

    2014-01-01

    Mixtures of silicone elastomer and silicone oil were prepared and the values of their Young’s moduli, E, determined in compression. The mixtures had volume fractions, ϕ, of silicone oil in the range of 0–0.73. Measurements were made, under displacement control, for strain rates, ε·, in the range of 0.04–3.85 s−1. The behaviour of E as a function of ϕ and ε· was investigated using a response surface model. The effects of the two variables were independent for the silicones used in this investigation. As a result, the dependence of E values (measured in MPa) on ϕ and ε· (s−1) could be represented by E=0.57−0.75ϕ+0.01loge(ε·). This means that these silicones can be mixed to give materials with E values in the range of about 0.02–0.57 MPa, which includes E values for many biological tissues. Thus, the mixtures can be used for making models for training health-care professionals and may be useful in some research applications as model tissues that do not exhibit biological variability. PMID:24951628

  2. Thermodynamics of a phase transition of silicon nanoparticles at the annealing and carbonization of porous silicon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nagornov, Yu. S., E-mail: Nagornov.Yuri@gmail.com

    2015-12-15

    The formation of SiC nanocrystals of the cubic modification in the process of high-temperature carbonization of porous silicon has been analyzed. A thermodynamic model has been proposed to describe the experimental data obtained by atomic-force microscopy, Raman scattering, spectral analysis, Auger spectroscopy, and X-ray diffraction spectroscopy. It has been shown that the surface energy of silicon nanoparticles and quantum filaments is released in the process of annealing and carbonization. The Monte Carlo simulation has shown that the released energy makes it possible to overcome the nucleation barrier and to form SiC nanocrystals. The processes of laser annealing and electron irradiationmore » of carbonized porous silicon have been analyzed.« less

  3. Tunable, antibacterial activity of silicone polyether surfactants.

    PubMed

    Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

    2015-08-01

    Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Prokaryotic silicon utilizing microorganisms in the biosphere

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Das, S.

    2012-12-01

    Although a little study has been done to determine the silicon utilizing prokaryotes, our previous experiments indicated that almost all Gram-positive bacteria are silicon utilizing; one of them, Streptococci survived exposure on the lunar surface for a long period in experiment done by others. Our initial experiments with these Gram positive microorganisms showed that there were limited growths of these microorganisms on carbon free silicate medium probably with the help of some carry over carbon and nitrogen during cultivation procedures. However, increase in growth rate after repeated subcultures could not be explained at present. The main groups of prokaryotes which were found silicon utilizing microorganisms were Mycobacterium, Bacillus, Nocardia, Streptomyces, Staphylococcus, Streptococcus, Lactobacillus, and Clostridium. In a another previous study by us when silicon level was studied in such grown up cells on carbon "free" silicate medium by electron prove microanalyser, it was found that silicon in cells grown on carbon "free" silicate medium was much higher (24.9%) than those grown on conventional carbon based medium (0.84%). However, these initial findings are encouraging for our future application of this group of organisms on extraterrestrial surfaces for artificial micro-ecosystem formation. It was found that when electropositive elements are less in extraterrestrial situation, then polymerization of silicon-oxygen profusion may occur easily, particularly in carbon and nitrogen paucity in the rocky worlds of the Universe.

  5. Development of AC-coupled, poly-silicon biased, p-on-n silicon strip detectors in India for HEP experiments

    NASA Astrophysics Data System (ADS)

    Jain, Geetika; Dalal, Ranjeet; Bhardwaj, Ashutosh; Ranjan, Kirti; Dierlamm, Alexander; Hartmann, Frank; Eber, Robert; Demarteau, Marcel

    2018-02-01

    P-on-n silicon strip sensors having multiple guard-ring structures have been developed for High Energy Physics applications. The study constitutes the optimization of the sensor design, and fabrication of AC-coupled, poly-silicon biased sensors of strip width of 30 μm and strip pitch of 55 μm. The silicon wafers used for the fabrication are of 4 inch n-type, having an average resistivity of 2-5 k Ω cm, with a thickness of 300 μm. The electrical characterization of these detectors comprises of: (a) global measurements of total leakage current, and backplane capacitance; (b) strip and voltage scans of strip leakage current, poly-silicon resistance, interstrip capacitance, interstrip resistance, coupling capacitance, and dielectric current; and (c) charge collection measurements using ALiBaVa setup. The results of the same are reported here.

  6. Flip-chip integrated silicon Mach-Zehnder modulator with a 28nm fully depleted silicon-on-insulator CMOS driver.

    PubMed

    Yong, Zheng; Shopov, Stefan; Mikkelsen, Jared C; Mallard, Robert; Mak, Jason C C; Voinigescu, Sorin P; Poon, Joyce K S

    2017-03-20

    We present a silicon electro-optic transmitter consisting of a 28nm ultra-thin body and buried oxide fully depleted silicon-on-insulator (UTBB FD-SOI) CMOS driver flip-chip integrated onto a Mach-Zehnder modulator. The Mach-Zehnder silicon optical modulator was optimized to have a 3dB bandwidth of around 25 GHz at -1V bias and a 50 Ω impedance. The UTBB FD-SOI CMOS driver provided a large output voltage swing around 5 Vpp to enable a high dynamic extinction ratio and a low device insertion loss. At 44 Gbps, the transmitter achieved a high extinction ratio of 6.4 dB at the modulator quadrature operation point. This result shows open eye diagrams at the highest bit rates and with the largest extinction ratios for silicon electro-optic transmitter using a CMOS driver.

  7. Thin-film silicon for flexible metal-air batteries.

    PubMed

    Garamoun, Ahmed; Schubert, Markus B; Werner, Jürgen H

    2014-12-01

    Due to its high energy density, theoretical studies propose silicon as a promising candidate material for metal-air batteries. Herein, for the first time, experimental results detail the use of n-type doped amorphous silicon and silicon carbide as fuel in Si-air batteries. Thin-film silicon is particularly interesting for flexible and rolled batteries with high specific energies. Our Si-air batteries exhibit a specific capacity of 269 Ah kg(-1) and an average cell voltage of 0.85 V at a discharge current density of 7.9 μA cm(-2) , corresponding to a specific energy of 229 Wh kg(-1) . Favorably in terms of safety, low concentrated alkaline solution serves as electrolyte. Discharging of the Si-air cells continues as long as there is silicon available for oxidation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Micromachined cutting blade formed from {211}-oriented silicon

    DOEpatents

    Fleming, James G.; Sniegowski, Jeffry J.; Montague, Stephen

    2003-09-09

    A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

  9. Micromachined cutting blade formed from {211}-oriented silicon

    DOEpatents

    Fleming, James G [Albuquerque, NM; Fleming, legal representative, Carol; Sniegowski, Jeffry J [Tijeras, NM; Montague, Stephen [Albuquerque, NM

    2011-08-09

    A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

  10. Fe₃O₄⁻Silicone Mixture as Flexible Actuator.

    PubMed

    Song, Kahye; Cha, Youngsu

    2018-05-08

    In this study, we introduce Fe₃O₄-silicone flexible composite actuators fabricated by combining silicone and iron oxide particles. The actuators exploit the flexibility of silicone and the electric conductivity of iron oxide particles. These actuators are activated by electrostatic force using the properties of the metal particles. Herein, we investigate the characteristic changes in actuation performance by increasing the concentration of iron oxide from 1% to 20%. The developed flexible actuators exhibit a resonant frequency near 3 Hz and their actuation amplitudes increase with increasing input voltage. We found that the actuator can move well at metal particle concentrations >2.5%. We also studied the changes in actuation behavior, depending on the portion of the Fe₃O₄-silicone in the length. Overall, we experimentally analyzed the characteristics of the newly proposed metal particle-silicone composite actuators.

  11. Enhanced Electroluminescence from Silicon Quantum Dots Embedded in Silicon Nitride Thin Films Coupled with Gold Nanoparticles in Light Emitting Devices

    PubMed Central

    Muñoz-Rosas, Ana Luz; Alonso-Huitrón, Juan Carlos

    2018-01-01

    Nowadays, the use of plasmonic metal layers to improve the photonic emission characteristics of several semiconductor quantum dots is a booming tool. In this work, we report the use of silicon quantum dots (SiQDs) embedded in a silicon nitride thin film coupled with an ultra-thin gold film (AuNPs) to fabricate light emitting devices. We used the remote plasma enhanced chemical vapor deposition technique (RPECVD) in order to grow two types of silicon nitride thin films. One with an almost stoichiometric composition, acting as non-radiative spacer; the other one, with a silicon excess in its chemical composition, which causes the formation of silicon quantum dots imbibed in the silicon nitride thin film. The ultra-thin gold film was deposited by the direct current (DC)-sputtering technique, and an aluminum doped zinc oxide thin film (AZO) which was deposited by means of ultrasonic spray pyrolysis, plays the role of the ohmic metal-like electrode. We found that there is a maximum electroluminescence (EL) enhancement when the appropriate AuNPs-spacer-SiQDs configuration is used. This EL is achieved at a moderate turn-on voltage of 11 V, and the EL enhancement is around four times bigger than the photoluminescence (PL) enhancement of the same AuNPs-spacer-SiQDs configuration. From our experimental results, we surmise that EL enhancement may indeed be due to a plasmonic coupling. This kind of silicon-based LEDs has the potential for technology transfer. PMID:29565267

  12. Prototype readout electronics and silicon strip detector study for the silicon tracking system at compressed baryonic matter experiment

    NASA Astrophysics Data System (ADS)

    Kasiński, Krzysztof; Szczygieł, Robert; Gryboś, Paweł

    2011-10-01

    This paper presents the prototype detector readout electronics for the STS (Silicon Tracking System) at CBM (Compressed Baryonic Matter) experiment at FAIR, GSI (Helmholtzzentrum fuer Schwerionenforschung GmbH) in Germany. The emphasis has been put on the strip detector readout chip and its interconnectivity with detector. Paper discusses the impact of the silicon strip detector and interconnection cable construction on the overall noise of the system and architecture of the TOT02 readout ASIC. The idea and problems of the double-sided silicon detector usage are also presented.

  13. Low cost silicon solar arrays

    NASA Technical Reports Server (NTRS)

    Ravi, K. V.; Serreze, H. B.; Bates, H. E.; Morrison, A. D.; Jewett, D. N.; Ho, J. C. T.; Schwuttke, G. H.; Ciszek, T. F.; Kran, A.

    1975-01-01

    Continuous growth methodology for silicon solar cell ribbons deals with capillary effects, die effects, thermal effects and crystal shape effects. Emphasis centers on the shape of the meniscus at the ribbon edge as a factor contributing to ribbon quality with respect to defect densities. Structural and electrical characteristics of edge defined, film-fed grown silicon ribbons are elaborated. Ribbon crystal solar cells produce AMO efficiencies of 6 to 10%.

  14. Process for making silicon from halosilanes and halosilicons

    NASA Technical Reports Server (NTRS)

    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.

  15. Ultrasonic Emission from Nanocrystalline Porous Silicon

    NASA Astrophysics Data System (ADS)

    Shinoda, Hiroyuki; Koshida, Nobuyoshi

    A simple layer structure composed of a metal thin film and a porous silicon layer on a silicon substrate generates intense and wide-band airborne ultrasounds. The large-bandwidth and the fidelity of the sound reproduction are leveraged in applications varying from sound-based measurement to a scientific study of animal ecology. This chapter describes the basic principle of the ultrasound generation. The macroscopic properties of the low thermal conductivity and the small heat capacity of nanocrystalline porous silicon thermally induce ultrasonic emission. The state-of-the-art of the achievable sound pressure and sound signal properties is introduced, with the technological and scientific applications of the devices.

  16. Superacid Passivation of Crystalline Silicon Surfaces.

    PubMed

    Bullock, James; Kiriya, Daisuke; Grant, Nicholas; Azcatl, Angelica; Hettick, Mark; Kho, Teng; Phang, Pheng; Sio, Hang C; Yan, Di; Macdonald, Daniel; Quevedo-Lopez, Manuel A; Wallace, Robert M; Cuevas, Andres; Javey, Ali

    2016-09-14

    The reduction of parasitic recombination processes commonly occurring within the silicon crystal and at its surfaces is of primary importance in crystalline silicon devices, particularly in photovoltaics. Here we explore a simple, room temperature treatment, involving a nonaqueous solution of the superacid bis(trifluoromethane)sulfonimide, to temporarily deactivate recombination centers at the surface. We show that this treatment leads to a significant enhancement in optoelectronic properties of the silicon wafer, attaining a level of surface passivation in line with state-of-the-art dielectric passivation films. Finally, we demonstrate its advantage as a bulk lifetime and process cleanliness monitor, establishing its compatibility with large area photoluminescence imaging in the process.

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

    NASA Astrophysics Data System (ADS)

    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 (<400sp°C). The double dilution was achieved by using a Ar (He) carrier for silane and its subsequent dilution by Hsb2. Structural and electrical properties of the films have been investigated over a wide growth space (temperature, power, pressure and dilution). Amorphous Si films deposited by silane diluted in He showed a compact nature and a hydrogen content of ˜8 at.% with a photo/dark conductivity ratio of 10sp4. Thin film transistors (W/L = 500/25) fabricated on these films, showed an on/off ratio of ˜10sp6 and a low threshold voltage of 2.92 volts. Microcrystalline Si films with a high crystalline content (˜80%) were also 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

  18. Stain-etched porous silicon nanostructures for multicrystalline silicon-based solar cells

    NASA Astrophysics Data System (ADS)

    Ben Rabha, M.; Hajji, M.; Belhadj Mohamed, S.; Hajjaji, A.; Gaidi, M.; Ezzaouia, H.; Bessais, B.

    2012-02-01

    In this paper, we study the optical, optoelectronic and photoluminescence properties of stain-etched porous silicon nanostructures obtained with different etching times. Special attention is given to the use of the stain-etched PS as an antireflection coating as well as for surface passivating capabilities. The surface morphology has been analyzed by scanning electron microscopy. The evolution of the Si-O and Si-H absorption bands was analyzed by Fourier transform infrared spectrometry before and after PS treatment. Results show that stain etching of the silicon surface drops the total reflectivity to about 7% in the 400-1100 nm wavelength range and the minority carrier lifetime enhances to about 48 μs.

  19. [Survey of silicone oil for ocular diseases in Japan].

    PubMed

    Sakamoto, Taiji; Hida, Tetsuo; Tano, Yasuo; Negi, Akira; Takeuchi, Shinobu; Ishibashi, Tatsuro; Inoue, Yoshitsugu; Ohguro, Nobuyuki; Okada, Annabelle Ayame

    2008-09-01

    To survey the use of silicone oil in clinical ophthalmology in Japan. Questionnaires were sent to 1,240 hospitals registered as being ophthalmology residency training institutions with the Japanese Ophthalmological Society as of September 2007. Responses were collected via the Internet and results totaled. The use of silicone oil at each institution for the 2006 one-year period was assessed, included queries regarding type of silicone oil, indication for use, results and complications. Hospitals were divided into non-specialty institutions, intermediate-specialty institutions and specialty institutions based on number of vitrectomy procedures performed in the one-year period, and trends were analyzed based on these divisions. Responses were received from 272 institutions (21.9% response rate). Of a total of 36,104 vitrectomy procedures, silicone oil was used in 2,170 cases (6.0%). The diagnosis was proliferative vitreoretinopathy in the majority of cases, followed by proliferative diabetic retinopathy and rhegmatogenous retinal detachment. The majority of institutions replied that the indication for use was complicated case. The type of silicone oil used was ophthalmic formulation in 120 institutions (54.1%) and industrial formulation in 73 institutions (32.9%). Specialty institutions had a higher rate of use of the industrial formulation. The average volume used at one time was 6.4 ml. The majority of institutions responded that silicone oil removal was performed at 3 months after the initial vitrectomy. Silicone oil was not removed in 530 cases in which continued tamponade was judged to be appropriate; this comprised 53.3% of cases at non-specialty institutions. The overall evaluation for silicone oil use was good; silicone oil was rated as being indispensable in 72 cases (31.2%) and effective in 130 cases (56.3%). Responses stating a high need for silicone oil were most frequent for proliferative vitreoretinopathy and proliferative diabetic retinopathy

  20. 21 CFR 573.940 - Silicon dioxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.940 Silicon dioxide. The food additive silicon dioxide may be safely used in animal feed in accordance with the following conditions: (a) The food additive is manufactured by vapor phase hydrolysis or...