WorldWideScience

Sample records for crystalline silicon dioxide

  1. Angstrom resolved imaging of charge percolation through the interface between phosphorous doped crystalline silicon and silicon dioxide

    Science.gov (United States)

    Ambal, Kapildep; Rahe, Philipp; Williams, Clayton C.; Boehme, Christoph

    2014-03-01

    Using a high resolution (~100fm/√{ Hz} spectral noise density) scanning probe at T ~4K, we measure currents through the interface between phosphorus doped ([P] ~ 1017-10qualitatively distinct I-V responses, each of which is identified with charge percolation from P donors to the cantilever either with or without different kinds of silicon dangling bond involvement. We acknowledge support by the National Science Foundation, Major Research Instrumentation Program #0959328.

  2. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  3. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

    2009-08-04

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

  4. Birefringence Measurements on Crystalline Silicon

    CERN Document Server

    Krüger, Christoph; Khalaidovski, Alexander; Steinlechner, Jessica; Nawrodt, Ronny; Schnabel, Roman; Lück, Harald

    2015-01-01

    Crystalline silicon has been proposed as a new test mass material in third generation gravitational wave detectors such as the Einstein Telescope (ET). Birefringence can reduce the interferometric contrast and can produce dynamical disturbances in interferometers. In this work we use the method of polarisation-dependent resonance frequency analysis of Fabry-Perot-cavities containing silicon as a birefringent medium. Our measurements show a birefringence of silicon along the (111) axis of the order of $\\Delta\\, n \\approx 10^{-7}$ at a laser wavelength of 1550nm and room temperature. A model is presented that explains the results of different settings of our measurements as a superposition of elastic strains caused by external stresses in the sample and plastic strains possibly generated during the production process. An application of our theory on the proposed ET test mass geometry suggests no critical effect on birefringence due to elastic strains.

  5. Amorphous silicon crystalline silicon heterojunction solar cells

    CERN Document Server

    Fahrner, Wolfgang Rainer

    2013-01-01

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

  6. 21 CFR 172.480 - Silicon dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Silicon dioxide. 172.480 Section 172.480 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.480 Silicon dioxide. The food additive silicon dioxide may be safely used in food...

  7. 21 CFR 573.940 - Silicon dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Silicon dioxide. 573.940 Section 573.940 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... Listing § 573.940 Silicon dioxide. The food additive silicon dioxide may be safely used in animal feed...

  8. Ultrathin, epitaxial cerium dioxide on silicon

    Science.gov (United States)

    Flege, Jan Ingo; Kaemena, Björn; Höcker, Jan; Bertram, Florian; Wollschläger, Joachim; Schmidt, Thomas; Falta, Jens

    2014-03-01

    It is shown that ultrathin, highly ordered, continuous films of cerium dioxide may be prepared on silicon following substrate prepassivation using an atomic layer of chlorine. The as-deposited, few-nanometer-thin Ce2O3 film may very effectively be converted at room temperature to almost fully oxidized CeO2 by simple exposure to air, as demonstrated by hard X-ray photoemission spectroscopy and X-ray diffraction. This post-oxidation process essentially results in a negligible loss in film crystallinity and interface abruptness.

  9. Bond Angles in the Crystalline Silicon/Silicon Nitride Interface

    Science.gov (United States)

    Leonard, Robert H.; Bachlechner, Martina E.

    2006-03-01

    Silicon nitride deposited on a silicon substrate has major applications in both dielectric layers in microelectronics and as antireflection and passivation coatings in photovoltaic applications. Molecular dynamic simulations are performed to investigate the influence of temperature and rate of externally applied strain on the structural and mechanical properties of the silicon/silicon nitride interface. Bond-angles between various atom types in the system are used to find and understand more about the mechanisms leading to the failure of the crystal. Ideally in crystalline silicon nitride, bond angles of 109.5 occur when a silicon atom is at the vertex and 120 angles occur when a nitrogen atom is at the vertex. The comparison of the calculated angles to the ideal values give information on the mechanisms of failure in silicon/silicon nitride system.

  10. Improved Josephson Qubits incorporating Crystalline Silicon Dielectrics

    Science.gov (United States)

    Gao, Yuanfeng; Maurer, Leon; Hover, David; Patel, Umeshkumar; McDermott, Robert

    2010-03-01

    Josephson junction phase quibts are a leading candidate for scalable quantum computing in the solid state. Their energy relaxation times are currently limited by microwave loss induced by a high density of two-level state (TLS) defects in the amorphous dielectric films of the circuit. It is expected that the integration of crystalline, defect-free dielectrics into the circuits will yield substantial improvements in qubit energy relaxation times. However, the epitaxial growth of a crystalline dielectric on a metal underlayer is a daunting challenge. Here we describe a novel approach in which the crystalline silicon nanomembrane of a Silicon-on-Insulator (SOI) wafer is used to form the junction shunt capacitor. The SOI wafer is thermocompression bonded to the device wafer. The handle and buried oxide layers of the SOI are then etched away, leaving the crystalline silicon layer for subsequent processing. We discuss device fabrication issues and present microwave transport data on lumped-element superconducting resonators incorporating the crystalline silicon.

  11. University Crystalline Silicon Photovoltaics Research and Development

    Energy Technology Data Exchange (ETDEWEB)

    Ajeet Rohatgi; Vijay Yelundur; Abasifreke Ebong; Dong Seop Kim

    2008-08-18

    The overall goal of the program is to advance the current state of crystalline silicon solar cell technology to make photovoltaics more competitive with conventional energy sources. This program emphasizes fundamental and applied research that results in low-cost, high-efficiency cells on commercial silicon substrates with strong involvement of the PV industry, and support a very strong photovoltaics education program in the US based on classroom education and hands-on training in the laboratory.

  12. Superacid Passivation of Crystalline Silicon Surfaces.

    Science.gov (United States)

    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.

  13. Donor-hydrogen complexes in crystalline silicon

    NARCIS (Netherlands)

    Liang, Z.N.; Niesen, L; Haas, C; Denteneer, P.J.H.

    1996-01-01

    Experimental results are presented on the study of Sb-H complexes in crystalline silicon, employing Sb-119 --> Sn-119 source Mossbauer spectroscopy and a low-energy H implantation technique. In addition to a visible component, we observe a large decrease of the Mossbauer intensity associated with

  14. Donor-hydrogen complexes in crystalline silicon

    NARCIS (Netherlands)

    Liang, Z.N.; Niesen, L; Haas, C; Denteneer, P.J.H.

    1996-01-01

    Experimental results are presented on the study of Sb-H complexes in crystalline silicon, employing Sb-119 --> Sn-119 source Mossbauer spectroscopy and a low-energy H implantation technique. In addition to a visible component, we observe a large decrease of the Mossbauer intensity associated with th

  15. Crystalline Silicon Dielectrics for Superconducting Qubit Circuits

    Science.gov (United States)

    Hover, David; Peng, Weina; Sendelbach, Steven; Eriksson, Mark; McDermott, Robert

    2009-03-01

    Superconducting qubit energy relaxation times are limited by microwave loss induced by a continuum of two-level state (TLS) defects in the dielectric materials of the circuit. State-of-the-art phase qubit circuits employ a micron-scale Josephson junction shunted by an external capacitor. In this case, the qubit T1 time is directly proportional to the quality factor (Q) of the capacitor dielectric. The amorphous capacitor dielectrics that have been used to date display intrinsic Q of order 10^3 to 10^4. Shunt capacitors with a Q of 10^6 are required to extend qubit T1 times well into the microsecond range. Crystalline dielectric materials are an attractive candidate for qubit capacitor dielectrics, due to the extremely low density of TLS defects. However, the robust integration of crystalline dielectrics with superconducting qubit circuits remains a challenge. Here we describe a novel approach to the realization of high-Q crystalline capacitor dielectrics for superconducting qubit circuits. The capacitor dielectric is a crystalline silicon nanomembrane. We discuss characterization of crystalline silicon capacitors with low-power microwave transport measurements at millikelvin temperatures. In addition, we report progress on integrating the crystalline capacitor process with Josephson qubit fabrication.

  16. Basic research challenges in crystalline silicon photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Werner, J.H. [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    1995-08-01

    Silicon is abundant, non-toxic and has an ideal band gap for photovoltaic energy conversion. Experimental world record cells of 24 % conversion efficiency with around 300 {mu}m thickness are only 4 % (absolute) efficiency points below the theoretical Auger recombination-limit of around 28 %. Compared with other photovoltaic materials, crystalline silicon has only very few disadvantages. The handicap of weak light absorbance may be mastered by clever optical designs. Single crystalline cells of only 48 {mu}m thickness showed 17.3 % efficiency even without backside reflectors. A technology of solar cells from polycrystalline Si films on foreign substrates arises at the horizon. However, the disadvantageous, strong activity of grain boundaries in Si could be an insurmountable hurdle for a cost-effective, terrestrial photovoltaics based on polycrystalline Si on foreign substrates. This talk discusses some basic research challenges related to a Si based photovoltaics.

  17. Mechanical Properties of Crystalline Silicon Carbide Nanowires.

    Science.gov (United States)

    Zhang, Huan; Ding, Weiqiang; Aidun, Daryush K

    2015-02-01

    In this paper, the mechanical properties of crystalline silicon carbide nanowires, synthesized with a catalyst-free chemical vapor deposition method, were characterized with nanoscale tensile testing and mechanical resonance testing methods inside a scanning electron microscope. Tensile testing of individual silicon carbide nanowire was performed to determine the tensile properties of the material including the tensile strength, failure strain and Young's modulus. The silicon carbide nanowires were also excited to mechanical resonance in the scanning electron microscope vacuum chamber using mechanical excitation and electrical excitation methods, and the corresponding resonance frequencies were used to determine the Young's modulus of the material according to the simple beam theory. The Young's modulus values from tensile tests were in good agreement with the ones obtained from the mechanical resonance tests.

  18. PREPARATION AND CHARACTERIZATION OF POLY-CRYSTALLINE SILICON THIN FILM

    Institute of Scientific and Technical Information of China (English)

    Y.F. Hu; H. Shen; Z.Y. Liu; L.S. Wen

    2003-01-01

    Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells.In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6. 05% without anti-reflection coating.

  19. Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

    Science.gov (United States)

    Lowden, Richard A.

    1994-01-01

    A process for chemical vapor deposition of crystalline silicon nitride which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide.

  20. Crystalline-silicon photovoltaics: Necessary and sufficient

    Science.gov (United States)

    Basore, P. A.; Gee, J. M.

    Photovoltaic (PV) energy systems have always been dominated by crystalline-silicon (c-Si) technology, and recent developments persuasively suggest that c-Si will continue to be the dominant technology well into the next century. The authors explain why c-Si technology is fairing much better than previously expected, and discuss the impact of improvements currently under development. They use a ground-up, engineering-based approach to predict the expected evolution of this type of PV system, and argue that c-Si PV will be in a position to compete for the US residential power market starting in about the year 2010. This market alone will provide the opportunity for PV to supply several percent of the electrical energy used in the United States. Crystalline-silicon technology is therefore not just necessary for building a near-term PV industry; it also offers a low-risk approach to meeting long-term goals for PV energy systems.

  1. 77 FR 63788 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2012-10-17

    ... modules, laminates, and panels, consisting of crystalline silicon photovoltaic cells, whether or not... modules, laminates, and panels, consisting of crystalline silicon photovoltaic cells, whether or not... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into...

  2. 77 FR 73017 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2012-12-07

    ... modules, laminates, and panels, consisting of crystalline silicon photovoltaic cells, whether or not... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules... issuing a countervailing duty order on crystalline silicon photovoltaic cells, whether or not...

  3. 77 FR 14732 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2012-03-13

    ... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules... of crystalline silicon photovoltaic cells, whether or not assembled into modules, from the People's.... \\1\\ See Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From...

  4. (Preoxidation cleaning optimization for crystalline silicon)

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    A series of controlled experiments has been performed in Sandia's Photovoltaic Device Fabrication Laboratory to evaluate the effect of various chemical surface treatments on the recombination lifetime of crystalline silicon wafers subjected to a high-temperature dry oxidation. From this series of experiments we have deduced a relatively simple yet effective cleaning sequence. We have also evaluated the effect of different chemical damage-removal etches for improving the recombination lifetime and surface smoothness of mechanically lapped wafers. This paper presents the methodology used, the experimental results obtained, and our experience with using this process on a continuing basis over a period of many months. 7 refs., 4 figs., 1 tab.

  5. Crystalline silicon cell performance at low light intensities

    NARCIS (Netherlands)

    Reich, N.H.|info:eu-repo/dai/nl/30483453X; van Sark, W.G.J.H.M.|info:eu-repo/dai/nl/074628526; Alsema, E.A.|info:eu-repo/dai/nl/073416258; Lof, R.W.; Schropp, R.E.I.|info:eu-repo/dai/nl/072502584; Sinke, W.C.|info:eu-repo/dai/nl/071641009; Turkenburg, W.C.|info:eu-repo/dai/nl/073416355

    2009-01-01

    Measured and modelled JV characteristics of crystalline silicon cells below one sun intensity have been investigated. First, the JV characteristics were measured between 3 and 1000 W/m2 at 6 light levels for 41 industrially produced mono- and multi-crystalline cells from 8 manufacturers, and at 29 i

  6. 76 FR 81914 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2011-12-29

    ... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules... of Commerce (the Department) initiated the countervailing duty investigation of crystalline silicon..., the preliminary determination is due no later than January 12, 2012. \\1\\ See Crystalline...

  7. 77 FR 37877 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2012-06-25

    ... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules... determination in the antidumping duty investigation of crystalline silicon photovoltaic cells, whether or not... (202) 482-4406, respectively. Correction In the Federal Register notice Crystalline...

  8. SIMILAR POINT-DEFECTS IN CRYSTALLINE AND AMORPHOUS-SILICON

    NARCIS (Netherlands)

    LIANG, ZN; NIESEN, L; VANDENHOVEN, GN; CUSTER, JS

    1994-01-01

    The microscopic nature of defects in ion-implanted crystalline silicon (c-Si) and amorphous silicon (a-Si) has been studied using Mossbauer spectroscopy. The evolution of the local structure around the probe atoms is followed during thermal annealing of ion-beam-created amorphous and ion-beam-damage

  9. Polymer grafting modification of the surface of nano silicon dioxide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the composite modification technology of the surface of nano silicon dioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on the surface of nano silicon dioxide. The modification mechanism and the bonding status on the surface of nano silicon dioxide after modification were suggested via the results of the infrared spectrum, transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formed by hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxide to form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto the surface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer through free radical polymerization between the double bonds on the surface of nano silicon dioxide and styrene under the action of initiating agent. The dispersibility of nano silicon dioxide and the controllability of surface modification of nano silicon dioxide can be greatly improved by the modification process.

  10. On Ultrafast Photoconductivity Dynamics and Crystallinity of Black Silicon

    DEFF Research Database (Denmark)

    Porte, Hendrik Pieter; Turchinovich, Dmitry; Persheyev, Saydulla;

    2013-01-01

    We investigate the carrier dynamics of thin films of black silicon, amorphous hydrogenated silicon which under laser annealing forms a microstructured surface with extremely high broadband optical absorption. We use Raman spectroscopy to determine the degree of crystallinity of the annealed...... surfaces, and investigate the dependence on crystallinity and fabrication method of the photoconductivity. Time-resolved THz spectroscopy is used to determine the evolution of the carrier scattering time and confinement of carriers on the picosecond time scale. We conclude that a fabrication method...... with high energy leading edge of the annealing laser results in black silicon with the largest photon-to-electron conversion efficiency, largest mobility, and longest carrier lifetime....

  11. Thermal Oxidation of Structured Silicon Dioxide

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Hansen, Ole; Jensen, Jørgen Arendt

    2014-01-01

    The topography of thermally oxidized, structured silicon dioxide is investigated through simulations, atomic force microscopy, and a proposed analytical model. A 357 nm thick oxide is structured by removing regions of the oxide in a masked etch with either reactive ion etching or hydrofluoric acid....... Subsequent thermal oxidation is performed in both dry and wet ambients in the temperature range 950◦C to 1100◦C growing a 205 ± 12 nm thick oxide in the etched mask windows. Lifting of the original oxide near the edge of the mask in the range 6 nm to 37 nm is seen with increased lifting for increasing...

  12. Laterally inherently thin amorphous-crystalline silicon heterojunction photovoltaic cell

    Science.gov (United States)

    Chowdhury, Zahidur R.; Kherani, Nazir P.

    2014-12-01

    This article reports on an amorphous-crystalline silicon heterojunction photovoltaic cell concept wherein the heterojunction regions are laterally narrow and distributed amidst a backdrop of well-passivated crystalline silicon surface. The localized amorphous-crystalline silicon heterojunctions consisting of the laterally thin emitter and back-surface field regions are precisely aligned under the metal grid-lines and bus-bars while the remaining crystalline silicon surface is passivated using the recently proposed facile grown native oxide-plasma enhanced chemical vapour deposited silicon nitride passivation scheme. The proposed cell concept mitigates parasitic optical absorption losses by relegating amorphous silicon to beneath the shadowed metallized regions and by using optically transparent passivation layer. A photovoltaic conversion efficiency of 13.6% is obtained for an untextured proof-of-concept cell illuminated under AM 1.5 global spectrum; the specific cell performance parameters are VOC of 666 mV, JSC of 29.5 mA-cm-2, and fill-factor of 69.3%. Reduced parasitic absorption, predominantly in the shorter wavelength range, is confirmed with external quantum efficiency measurement.

  13. Thin-film crystalline silicon solar cells

    CERN Document Server

    Brendel, Rolf

    2011-01-01

    This introduction to the physics of silicon solar cells focuses on thin cells, while reviewing and discussing the current status of the important technology. An analysis of the spectral quantum efficiency of thin solar cells is given as well as a full set of analytical models. This is the first comprehensive treatment of light trapping techniques for the enhancement of the optical absorption in thin silicon films.

  14. Transistors using crystalline silicon devices on glass

    Science.gov (United States)

    McCarthy, A.M.

    1995-05-09

    A method is disclosed for fabricating transistors using single-crystal silicon devices on glass. This method overcomes the potential damage that may be caused to the device during high voltage bonding and employs a metal layer which may be incorporated as part of the transistor. This is accomplished such that when the bonding of the silicon wafer or substrate to the glass substrate is performed, the voltage and current pass through areas where transistors will not be fabricated. After removal of the silicon substrate, further metal may be deposited to form electrical contact or add functionality to the devices. By this method both single and gate-all-around devices may be formed. 13 figs.

  15. Reduction of the environmental impacts in crystalline silicon module manufacturing

    NARCIS (Netherlands)

    Alsema, E.A.; de Wild-Schoten, M.J.

    2007-01-01

    In this paper we review the most important options to reduce environmental impacts of crystalline silicon modules. We investigate which are the main barriers for implementation of the measure. Finally we review which measures to reduce environmental impacts could also lead to a cost reduction. Reduc

  16. High quality crystalline silicon surface passivation by combined intrinsic and n-type hydrogenated amorphous silicon

    NARCIS (Netherlands)

    Schuttauf, J.A.; van der Werf, C.H.M.; Kielen, I.M.; van Sark, W.G.J.H.M.; Rath, J.K.

    2011-01-01

    We investigate the influence of thermal annealing on the passivation quality of crystalline silicon (c-Si) surfaces by intrinsic and n-type hydrogenated amorphous silicon (a-Si:H) films. For temperatures up to 255 C, we find an increase in surface passivation quality, corresponding to a decreased da

  17. 76 FR 78313 - Crystalline Silicon Photovoltaic Cells and Modules From China

    Science.gov (United States)

    2011-12-16

    ... COMMISSION Crystalline Silicon Photovoltaic Cells and Modules From China Determinations On the basis of the... is materially injured by reason of imports from China of crystalline silicon photovoltaic cells and... crystalline silicon photovoltaic cells and modules from China. Accordingly, effective October 19, 2011,...

  18. 77 FR 10478 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2012-02-22

    ... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules... crystalline silicon photovoltaic cells, whether or not assembled into modules, from the People's Republic of..., 2012, which the Department granted.\\2\\ \\1\\ See Crystalline Silicon Photovoltaic Cells, Whether or...

  19. 77 FR 25400 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2012-04-30

    ... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules... in this countervailing duty (CVD) investigation of crystalline silicon photovoltaic cells, whether or... 19 CFR 351.210(b)(4)(i) and 210(i). \\1\\ See Crystalline Silicon Photovoltaic Cells, Whether or...

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

    Energy Technology Data Exchange (ETDEWEB)

    Boccard, Mathieu; Holman, Zachary C. [School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona 85287-5706 (United States)

    2015-08-14

    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 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.

  1. Inkjet technology for crystalline silicon photovoltaics.

    Science.gov (United States)

    Stüwe, David; Mager, Dario; Biro, Daniel; Korvink, Jan G

    2015-01-27

    The world's ever increasing demand for energy necessitates technologies that generate electricity from inexhaustible and easily accessible energy sources. Silicon photovoltaics is a technology that can harvest the energy of sunlight. Its great characteristics have fueled research and development activities in this exciting field for many years now. One of the most important activities in the solar cell community is the investigation of alternative fabrication and structuring technologies, ideally serving both of the two main goals: device optimization and reduction of fabrication costs. Inkjet technology is practically evaluated along the whole process chain. Research activities cover many processes, such as surface texturing, emitter formation, or metallization. Furthermore, the inkjet technology itself is manifold as well. It can be used to apply inks that serve as a functional structure, present in the final device, as mask for subsequent structuring steps, or even serve as a reactant source to activate chemical etch reactions. This article reviews investigations of inkjet-printing in the field of silicon photovoltaics. The focus is on the different inkjet processes for individual fabrication steps of a solar cell. A technological overview and suggestions about where future work will be focused on are also provided. The great variety of the investigated processes highlights the ability of the inkjet technology to find its way into many other areas of functional printing and printed electronics.

  2. Crystalline silicon photovoltaics via low-temperature TiO 2/Si and PEDOT/Si heterojunctions

    Science.gov (United States)

    Nagamatsu, Ken Alfred

    The most important goals in developing solar cell technology are to achieve high power conversion efficiencies and lower costs of manufacturing. Solar cells based on crystalline silicon currently dominate the market because they can achieve high efficiency. However, conventional p-n junction solar cells require high-temperature diffusions of dopants, and conventional heterojunction cells based on amorphous silicon require plasma-enhanced deposition, both of which can add manufacturing costs. This dissertation investigates an alternative approach, which is to form crystalline-silicon-based solar cells using heterojunctions with materials that are easily deposited at low temperatures and without plasma enhancement, such as organic semiconductors and metal oxides. We demonstrate a heterojunction between the organic polymer, poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT), and crystalline silicon, which acts as a hole-selective contact and an alternative to a diffused p-n junction. We also present the use of a heterojunction between titanium dioxide and crystalline silicon as a passivating electron-selective contact. The Si/TiO2 heterojunction is demonstrated for the first time as a back-surface field in a crystalline silicon solar cell, and is incorporated into a PEDOT/Si device. The resulting PEDOT/Si/TiO2 solar cell represents an alternative to conventional silicon solar cells that rely on thermally-diffused junctions or plasma-deposited heterojunctions. Finally, we investigate the merits of using conductive networks of silver nanowires to enhance the photovoltaic performance of PEDOT/Si solar cells. The investigation of these materials and devices contributes to the growing body of work regarding crystalline silicon solar cells made with selective contacts.

  3. Low temperature plasma deposition of silicon thin films: From amorphous to crystalline

    OpenAIRE

    Roca i Cabarrocas, Pere; Cariou, Romain; Labrune, Martin

    2012-01-01

    International audience; We report on the epitaxial growth of crystalline silicon films on (100) oriented crystalline silicon substrates by standard plasma enhanced chemical vapor deposition at 175 °C. Such unexpected epitaxial growth is discussed in the context of deposition processes of silicon thin films, based on silicon radicals and nanocrystals. Our results are supported by previous studies on plasma synthesis of silicon nanocrystals and point toward silicon nanocrystals being the most p...

  4. A holistic view of crystalline silicon module reliability

    Energy Technology Data Exchange (ETDEWEB)

    Hanoka, J.I. [Evergreen Solar, Inc., Waltham, MA (United States)

    1995-11-01

    Several aspects of module reliability are discussed, particularly with reference to the encapsulant and its interaction with the metallization and interconnection of a module. A need to look at the module as a whole single unit is stressed. Also, the issue of a slight light degradation effect in crystalline silicon cells is discussed. A model for this is mentioned and it may well be that polycrystalline cells with dislocations may have an advantage.

  5. Crystalline-silicon reliability lessons for thin-film modules

    Science.gov (United States)

    Ross, R. G., Jr.

    1985-01-01

    The reliability of crystalline silicon modules has been brought to a high level with lifetimes approaching 20 years, and excellent industry credibility and user satisfaction. The transition from crystalline modules to thin film modules is comparable to the transition from discrete transistors to integrated circuits. New cell materials and monolithic structures will require new device processing techniques, but the package function and design will evolve to a lesser extent. Although there will be new encapsulants optimized to take advantage of the mechanical flexibility and low temperature processing features of thin films, the reliability and life degradation stresses and mechanisms will remain mostly unchanged. Key reliability technologies in common between crystalline and thin film modules include hot spot heating, galvanic and electrochemical corrosion, hail impact stresses, glass breakage, mechanical fatigue, photothermal degradation of encapsulants, operating temperature, moisture sorption, circuit design strategies, product safety issues, and the process required to achieve a reliable product from a laboratory prototype.

  6. Delineation of Crystalline Extended Defects on Multicrystalline Silicon Wafers

    Directory of Open Access Journals (Sweden)

    Mohamed Fathi

    2007-01-01

    Full Text Available We have selected Secco and Yang etch solutions for the crystalline defect delineation on multicrystalline silicon (mc-Si wafers. Following experimentations and optimization of Yang and Secco etching process parameters, we have successfully revealed crystalline extended defects on mc-Si surfaces. A specific delineation process with successive application of Yang and Secco agent on the same sample has proved the increased sensitivity of Secco etch to crystalline extended defects in mc-Si materials. The exploration of delineated mc-Si surfaces indicated that strong dislocation densities are localized mainly close to the grain boundaries and on the level of small grains in size (below 1 mm. Locally, we have observed the formation of several parallel dislocation lines, perpendicular to the grain boundaries. The overlapping of several dislocations lines has revealed particular forms for etched pits of dislocations.

  7. Mechanically flexible optically transparent porous mono-crystalline silicon substrate

    KAUST Repository

    Rojas, Jhonathan Prieto

    2012-01-01

    For the first time, we present a simple process to fabricate a thin (≥5μm), mechanically flexible, optically transparent, porous mono-crystalline silicon substrate. Relying only on reactive ion etching steps, we are able to controllably peel off a thin layer of the original substrate. This scheme is cost favorable as it uses a low-cost silicon <100> wafer and furthermore it has the potential for recycling the remaining part of the wafer that otherwise would be lost and wasted during conventional back-grinding process. Due to its porosity, it shows see-through transparency and potential for flexible membrane applications, neural probing and such. Our process can offer flexible, transparent silicon from post high-thermal budget processed device wafer to retain the high performance electronics on flexible substrates. © 2012 IEEE.

  8. Effect of Silicon Nanowire on Crystalline Silicon Solar Cell Characteristics

    Directory of Open Access Journals (Sweden)

    Zahra Ostadmahmoodi Do

    2016-06-01

    Full Text Available Nanowires (NWs are recently used in several sensor or actuator devices to improve their ordered characteristics. Silicon nanowire (Si NW is one of the most attractive one-dimensional nanostructures semiconductors because of its unique electrical and optical properties. In this paper, silicon nanowire (Si NW, is synthesized and characterized for application in photovoltaic device. Si NWs are prepared using wet chemical etching method which is commonly used as a simple and low cost method for producing nanowires of the same substrate material. The process conditions are adjusted to find the best quality of Si NWs. Morphology of Si NWs is studied using a field emission scanning electron microscopic technique. An energy dispersive X-Ray analyzer is also used to provide elemental identification and quantitative compositional information. Subsequently, Schottky type solar cell samples are fabricated on Si and Si NWs using ITO and Ag contacts. The junction properties are calculated using I-V curves in dark condition and the solar cell I-V characteristics are obtained under incident of the standardized light of AM1.5. The results for the two mentioned Schottky solar cell samples are compared and discussed. An improvement in short circuit current and efficiency of Schottky solar cell is found when Si nanowires are employed.

  9. Cytotoxicity of titanium and silicon dioxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Stefanie; Scheper, Thomas; Bahnemann, Detlef; Kasper, Cornelia [Institut fuer Technische Chemie, Leibniz Universitaet Hannover, Callinstr.5, 30167 Hannover (Germany)], E-mail: wagner@iftc.uni-hannover.de; Muenzer, Simon; Behrens, Peter [Institut fuer Anorganische Chemie, Leibniz Universitaet Hannover, Callinstr.9, 30167 Hannover (Germany)

    2009-05-01

    Different TiO{sub 2} and SiO{sub 2} nanoparticles have been tested concerning their toxicity on selected mammalian cell lines. Various powders and suspensions, all of which consist of titanium or silicon dioxide nanoparticles have been examined. These particles differ in the crystal structure, the size and the BET-surface area. There was also a classification in fixed particles and in particles easily accessible in solution. With focus on the possible adsorption of the nanoparticles into the human organism, via skin and via respiratory tract, the effects on fibroblasts (NIH-3T3) and on a human lung adenocarcinoma epithelial cell line were examined. Additionally, the particles were tested with HEP-G2 cells, which are often used as model cell line for biocompatibility tests, and PC-12 cells, a rat adrenal pheochromocytoma cell line. The viability of the cells was examined by the MTT-test. The viability results were found to partly depend on the type of cells used. The experimental results show that the adhesion of the cells on the different powders strongly depends on the type of cell lines as well as on the type of powder. It was found that the lower viability of some cells on the powder coatings is not only caused by a cytotoxicity effect of the powders, but is also due to a lower adhesion of the cells on the particle surfaces. Furthermore, it could be shown that the physical properties of the powders cannot be easily correlated to any observed biological effect. While some powders show a significant suppression of the cell growth, others with similar physical properties indicate no toxic effect.

  10. 77 FR 4764 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Science.gov (United States)

    2012-01-31

    ... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules... duty investigation of crystalline silicon photovoltaic cells, whether or not assembled into modules, ] from the People's Republic of China, to no later than February 13, 2012.\\1\\ \\1\\ See Crystalline...

  11. A hybrid life-cycle inventory for multi-crystalline silicon PV module manufacturing in China

    Science.gov (United States)

    Yao, Yuan; Chang, Yuan; Masanet, Eric

    2014-11-01

    China is the world’s largest manufacturer of multi-crystalline silicon photovoltaic (mc-Si PV) modules, which is a key enabling technology in the global transition to renewable electric power systems. This study presents a hybrid life-cycle inventory (LCI) of Chinese mc-Si PV modules, which fills a critical knowledge gap on the environmental implications of mc-Si PV module manufacturing in China. The hybrid LCI approach combines process-based LCI data for module and poly-silicon manufacturing plants with a 2007 China IO-LCI model for production of raw material and fuel inputs to estimate ‘cradle to gate’ primary energy use, water consumption, and major air pollutant emissions (carbon dioxide, methane, sulfur dioxide, nitrous oxide, and nitrogen oxides). Results suggest that mc-Si PV modules from China may come with higher environmental burdens that one might estimate if one were using LCI results for mc-Si PV modules manufactured elsewhere. These higher burdens can be reasonably explained by the efficiency differences in China’s poly-silicon manufacturing processes, the country’s dependence on highly polluting coal-fired electricity, and the expanded system boundaries associated with the hybrid LCI modeling framework. The results should be useful for establishing more conservative ranges on the potential ‘cradle to gate’ impacts of mc-Si PV module manufacturing for more robust LCAs of PV deployment scenarios.

  12. 77 FR 72884 - Crystalline Silicon Photovoltaic Cells and Modules From China

    Science.gov (United States)

    2012-12-06

    ... COMMISSION Crystalline Silicon Photovoltaic Cells and Modules From China Determinations On the basis of the... reason of imports of crystalline silicon photovoltaic cells and modules from China, provided for in... silicon photovoltaic cells and modules from China. Chairman Irving A. Williamson and Commissioner Dean...

  13. Novel Scheme of Amorphous/Crystalline Silicon Heterojunction Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    De Iuliis, S.; Geerligs, L.J. [ECN Solar Energy, Petten (Netherlands); Tucci, M.; Serenelli, L.; Salza, E. [ENEA Research Center Casaccia, Roma (Italy); De Cesare, G.; Caputo, D.; Ceccarelli, M. [University ' Sapienza' , Department of Electronic Engineering, Roma (Italy)

    2007-01-15

    In this paper we investigate in detail how the heterostructure concept can be implemented in an interdigitated back contact solar cell, in which both the emitters are formed on the back side of the c-Si wafer by amorphous/crystalline silicon heterostructure, and at the same time the grid-less front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides an anti-reflection coating. The entire process, held at temperature below 300C, is photolithography-free, using a metallic self-aligned mask to create the interdigitated pattern, and we show that the alignment is feasible. An open-circuit voltage of 687 mV has been measured on a p-type monocrystalline silicon wafer. The mask-assisted deposition process does not influence the uniformity of the deposited amorphous silicon layers. Photocurrent limits factor has been investigated with the aid of one-dimensional modeling and quantum efficiency measurements. On the other hand several technological aspects that limit the fill factor and the short circuit current density still need improvements.

  14. Inexpensive transparent nanoelectrode for crystalline silicon solar cells.

    Science.gov (United States)

    Peng, Qiang; Pei, Ke; Han, Bing; Li, Ruopeng; Zhou, Guofu; Liu, Jun-Ming; Kempa, Krzysztof; Gao, Jinwei

    2016-12-01

    We report an easily manufacturable and inexpensive transparent conductive electrode for crystalline silicon (c-Si) solar cells. It is based on a silver nanoparticle network self-forming in the valleys between the pyramids of a textured solar cell surface, transformed into a nanowire network by sintering, and subsequently "buried" under the silicon surface by a metal-assisted chemical etching. We have successfully incorporated these steps into the conventional c-Si solar cell manufacturing process, from which we have eliminated the expensive screen printing and firing steps, typically used to make the macro-electrode of conducting silver fingers. The resulting, preliminary solar cell achieved power conversion efficiency only 14 % less than the conventionally processed c-Si control cell. We expect that a cell with an optimized processing will achieve at least efficiency of the conventional commercial cell, but at significantly reduced manufacturing cost.

  15. Inexpensive transparent nanoelectrode for crystalline silicon solar cells

    Science.gov (United States)

    Peng, Qiang; Pei, Ke; Han, Bing; Li, Ruopeng; Zhou, Guofu; Liu, Jun-Ming; Kempa, Krzysztof; Gao, Jinwei

    2016-06-01

    We report an easily manufacturable and inexpensive transparent conductive electrode for crystalline silicon (c-Si) solar cells. It is based on a silver nanoparticle network self-forming in the valleys between the pyramids of a textured solar cell surface, transformed into a nanowire network by sintering, and subsequently "buried" under the silicon surface by a metal-assisted chemical etching. We have successfully incorporated these steps into the conventional c-Si solar cell manufacturing process, from which we have eliminated the expensive screen printing and firing steps, typically used to make the macro-electrode of conducting silver fingers. The resulting, preliminary solar cell achieved power conversion efficiency only 14 % less than the conventionally processed c-Si control cell. We expect that a cell with an optimized processing will achieve at least efficiency of the conventional commercial cell, but at significantly reduced manufacturing cost.

  16. Crystalline silicon solar cells with high resistivity emitter

    Science.gov (United States)

    Panek, P.; Drabczyk, K.; Zięba, P.

    2009-06-01

    The paper presents a part of research targeted at the modification of crystalline silicon solar cell production using screen-printing technology. The proposed process is based on diffusion from POCl3 resulting in emitter with a sheet resistance on the level of 70 Ω/□ and then, shaped by high temperature passivation treatment. The study was focused on a shallow emitter of high resistivity and on its influence on output electrical parameters of a solar cell. Secondary ion mass spectrometry (SIMS) has been employed for appropriate distinguishing the total donor doped profile. The solar cell parameters were characterized by current-voltage characteristics and spectral response (SR) methods. Some aspects playing a role in suitable manufacturing process were discussed. The situation in a photovoltaic industry with emphasis on silicon supply and current prices of solar cells, modules and photovoltaic (PV) systems are described. The economic and quantitative estimation of the PV world market is shortly discussed.

  17. Hydrogen passivation of multi-crystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    胡志华; 廖显伯; 刘祖明; 夏朝凤; 陈庭金

    2003-01-01

    The effects of hydrogen passivation on multi-crystalline silicon (mc-Si) solar cells are reported in this paper.Hydrogen plasma was generated by means of ac glow discharge in a hydrogen atmosphere. Hydrogen passivation was carried out with three different groups of mc-Si solar cells after finishing contacts. The experimental results demonstrated that the photovoltaic performances of the solar cell samples have been improved after hydrogen plasma treatment, with a relative increase in conversion efficiency up to 10.6%. A calculation modelling has been performed to interpret the experimental results using the model for analysis of microelectronic and photonic structures developed at Pennsylvania State University.

  18. 77 FR 35425 - Crystalline Silicon Photovoltaic Cells and Modules From China; Scheduling of the Final Phase of...

    Science.gov (United States)

    2012-06-13

    ... silicon photovoltaic cells, and modules, laminates, and panels, consisting of crystalline silicon... COMMISSION Crystalline Silicon Photovoltaic Cells and Modules From China; Scheduling of the Final Phase of... crystalline silicon photovoltaic cells and modules, provided for in subheadings 8501.31.80, 8501.61.00,...

  19. Determining the Onset of Amorphization of Crystalline Silicon due to Hypervelocity Impact

    Science.gov (United States)

    Poletti, C. Shane; Bachlechner, Martina E.

    2009-03-01

    Atomistic simulations were performed to study a hypervelocity impactor striking a silicon/silicon nitride interface with varying silicon substrate thicknesses. Visualization indicates that the crystalline silicon amorphizes upon impact. The objective of the present study is to determine where the boundary between amorphous and crystalline silicon occurrs. In the analysis, the silicon substrate is separated into sixty layers and for each layer the average z displacement is determined. Our results show that the boundary between amorphous and crystalline silicon occurs between layers 20 and 22 for an impactor traveling at 5 km/s. This corresponds to a depth of approximately 32 Angstroms into the silicon. More detailed analyses reveals that the z displacement is noticeably larger for the layers that do not have a silicon atom bonded beneath them compared to the ones that do.

  20. TOPICAL REVIEW: New crystalline silicon ribbon materials for photovoltaics

    Science.gov (United States)

    Hahn, G.; Schönecker, A.

    2004-12-01

    The objective of this article is to review, in relation to photovoltaic applications, the current status of crystalline silicon ribbon technologies as an alternative to technologies based on wafers originating from ingots. Increased wafer demand, the foreseeable silicon feedstock shortage, and the need for a substantial module cost reduction are the main issues that must be faced in the booming photovoltaic market. Ribbon technologies make excellent use of silicon, as wafers are crystallized directly from the melt at the desired thickness and no kerf losses occur. Therefore, they offer a high potential for significantly reducing photovoltaic electricity costs as compared to technology based on wafers cut from ingots. However, the defect structure present in the ribbon silicon wafers can limit material quality and cell efficiency. We will review the most successful of the ribbon techniques already used in large scale production or currently in the pilot demonstration phase, with special emphasis on the defects incorporated during crystal growth. Because of the inhomogeneous distribution of defects, mapped characterization techniques have to be applied. Al and P gettering studies give an insight into the complex interaction of defects in the multicrystalline materials as the gettering efficiency is influenced by the state of the chemical bonding of the metal atoms. The most important technique for improvement of carrier lifetimes is hydrogenation, whose kinetics are strongly influenced by oxygen and carbon concentrations present in the material. The best cell efficiencies for laboratory-type (17%-18% cell area: 4 cm2) as well as industrial-type (15%-16% cell area: {\\ge } 80~{\\mathrm {cm^{2}}} ) ribbon silicon solar cells are in the same range as for standard wafers cut from ingots. A substantial cost reduction therefore seems achievable, although the most promising techniques need to be improved.

  1. Crystalline silicon cell performance at low light intensities

    Energy Technology Data Exchange (ETDEWEB)

    Reich, N.H.; van Sark, W.G.J.H.M.; Alsema, E.A.; Turkenburg, W.C. [Utrecht University, Faculty of Science, Copernicus Institute for Sustainable Development and Innovation, Department of Science, Techonology and Society, Heidelberglaan 2, 3584 CS Utrecht (Netherlands); Lof, R.W.; Schropp, R.E.I. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, Nanophotonics - Physics of Device, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht (Netherlands); Sinke, W.C. [Energy research Centre of the Netherlands (ECN), P.O. Box 1, 1755 ZG Petten (Netherlands)

    2009-09-15

    Measured and modelled JV characteristics of crystalline silicon cells below one sun intensity have been investigated. First, the JV characteristics were measured between 3 and 1000 W/m{sup 2} at 6 light levels for 41 industrially produced mono- and multi-crystalline cells from 8 manufacturers, and at 29 intensity levels for a single multi-crystalline silicon between 0.01 and 1000 W/m{sup 2}. Based on this experimental data, the accuracy of the following four modelling approaches was evaluated: (1) empirical fill factor expressions, (2) a purely empirical function, (3) the one-diode model and (4) the two-diode model. Results show that the fill factor expressions and the empirical function fail at low light intensities, but a new empirical equation that gives accurate fits could be derived. The accuracy of both diode models are very high. However, the accuracy depends considerably on the used diode model parameter sets. While comparing different methods to determine diode model parameter sets, the two-diode model is found to be preferred in principle: particularly its capability in accurately modelling V{sub OC} and efficiency with one and the same parameter set makes the two-diode model superior. The simulated energy yields of the 41 commercial cells as a function of irradiance intensity suggest unbiased shunt resistances larger than about 10 k{omega} cm{sup 2} may help to avoid low energy yields of cells used under predominantly low light intensities. Such cells with diode currents not larger than about 10{sup -9} A/cm{sup 2} are excellent candidates for Product Integrated PV (PIPV) appliances. (author)

  2. Multi-crystalline silicon solidification under controlled forced convection

    Science.gov (United States)

    Cablea, M.; Zaidat, K.; Gagnoud, A.; Nouri, A.; Chichignoud, G.; Delannoy, Y.

    2015-05-01

    Multi-crystalline silicon wafers have a lower production cost compared to mono-crystalline wafers. This comes at the price of reduced quality in terms of electrical properties and as a result the solar cells made from such materials have a reduced efficiency. The presence of different impurities in the bulk material plays an important role during the solidification process. The impurities are related to different defects (dislocations, grain boundaries) encountered in multi-crystalline wafers. Applying an alternative magnetic field during the solidification process has various benefits. Impurities concentration in the final ingot could be reduced, especially metallic species, due to a convective term added in the liquid that reduces the concentration of impurities in the solute boundary layer. Another aspect is the solidification interface shape that is influenced by the electromagnetic stirring. A vertical Bridgman type furnace was used in order to study the solidification process of Si under the influence of a travelling magnetic field able to induce a convective flow in the liquid. The furnace was equipped with a Bitter type three-phase electromagnet that provides the required magnetic field. A numerical model of the furnace was developed in ANSYS Fluent commercial software. This paper presents experimental and numerical results of this approach, where interface markings were performed.

  3. Test-to-Failure of Crystalline Silicon Modules: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, P.; Terwilliger, K.; Glick, S.; Trudell, D.; Bosco, N.; Johnston, S.; Kurtz, S. R.

    2010-10-01

    Accelerated lifetime testing of five crystalline silicon module designs was carried out according to the Terrestrial Photovoltaic Module Accelerated Test-to-Failure Protocol. This protocol compares the reliability of various module constructions on a quantitative basis. The modules under test are subdivided into three accelerated lifetime testing paths: 85..deg..C/85% relative humidity with system bias, thermal cycling between ?40..deg..C and 85..deg..C, and a path that alternates between damp heat and thermal cycling. The most severe stressor is damp heat with system bias applied to simulate the voltages that modules experience when connected in an array. Positive 600 V applied to the active layer with respect to the grounded module frame accelerates corrosion of the silver grid fingers and degrades the silicon nitride antireflective coating on the cells. Dark I-V curve fitting indicates increased series resistance and saturation current around the maximum power point; however, an improvement in junction recombination characteristics is obtained. Shunt paths and cell-metallization interface failures are seen developing in the silicon cells as determined by electroluminescence, thermal imaging, and I-V curves in the case of negative 600 V bias applied to the active layer. Ability to withstand electrolytic corrosion, moisture ingress, and ion drift under system voltage bias are differentiated.

  4. Optical and electrical characterization of crystalline silicon films formed by rapid thermal annealing of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Baldus-Jeursen, Christopher, E-mail: cjbaldus@uwaterloo.ca; Tarighat, Roohollah Samadzadeh, E-mail: rsamadza@uwaterloo.ca; Sivoththaman, Siva, E-mail: sivoththaman@uwaterloo.ca

    2016-03-31

    The effect of rapid thermal annealing (RTA) on n-type hydrogenated amorphous silicon (a-Si:H) films deposited on single-crystal silicon (c-Si) wafers was studied by electrical and optical methods. Deposition of a-Si:H films by plasma-enhanced chemical vapor deposition (PECVD) was optimized for high deposition rate and maximum film uniformity. RTA processed films were characterized by spreading resistance profiling (SRP), Hall effect, spectroscopic ellipsometry, defect etching, and transmission electron microscopy (TEM). It was found that the films processed between 600 °C and 1000 °C were highly crystalline and that the defect density in the films diminished with increasing thermal budget. Junctions formed by the RTA processed n-type a-Si:H films on p-type c-Si wafers were tested for device applicability. It was established that these films can be used as the emitter layer in n{sup +}p photovoltaic (PV) devices with over 14% conversion efficiency. - Highlights: • Rapid thermal annealing of doped amorphous silicon deposited on single-crystal silicon (c-Si) wafers resulted in highly crystalline films for photovoltaic devices. • As the annealing temperature increased, the electrical and optical properties of the films became increasingly similar to single-crystal silicon. • Annealing temperatures between 500-1000 oC were investigated. Solar cell devices fabricated after annealing at 750 oC were found to be the most suitable compromise between good quality crystalline films and minimal dopant diffusion into the c-Si wafer. • Annealed films were highly conductive without the need for a transparent conducting oxide.

  5. Reduction Bending of Thin Crystalline Silicon Solar Cells

    Institute of Scientific and Technical Information of China (English)

    SHEN Lan-xian; LIU Zu-ming; LIAO Hua; TU Jie-lei; DENG Shu-kang

    2009-01-01

    Reported are the results of reduction the bending of thin crystalline silicon solar ceils after printing and sintering of back electrode by changing the back electrode paste and adjusting the screen printing parameters without effecting the electrical properties of the cell. Theory and experiments showed that the bending of the cell is changed with its thickness of suhstrate, the thinner cell, the more serious bending. The bending of the cell is decreased with the thickness decrease of the back contact paste. The substrate with the thickness of 190μm printing with sheet aluminum paste shows a relatively lower bend compared with that of the substrate printing with ordinary aluminum paste, and the minimum bend is 0.55 mm which is reduced by52%.

  6. Properties of interfaces in amorphous/crystalline silicon heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Olibet, Sara; Vallat-Sauvain, Evelyne; Fesquet, Luc; Damon-Lacoste, Jerome; De Wolf, Stefaan; Ballif, Christophe [Ecole Polytechnique Federale de Lausanne (EPFL), IMT, Photovoltaics and Thin Film Electronics Laboratory, Breguet 2, 2000 Neuchatel (Switzerland); Monachon, Christian; Hessler-Wyser, Aicha [Ecole Polytechnique Federale de Lausanne (EPFL), Interdisciplinary Centre for Electron Microscopy (CIME), 1015 Lausanne (Switzerland)

    2010-03-15

    To study recombination at the amorphous/crystalline Si (a-Si:H/c-Si) heterointerface, the amphoteric nature of silicon (Si) dangling bonds is taken into account. Modeling interface recombination measured on various test structures provides insight into the microscopic passivation mechanisms, yielding an excellent interface defect density reduction by intrinsic a-Si:H and tunable field-effect passivation by doped layers. The potential of this model's applicability to recombination at other Si heterointerfaces is demonstrated. Solar cell properties of a-Si:H/c-Si heterojunctions are in good accordance with the microscopic interface properties revealed by modeling, that are, e.g., slight asymmetries in the neutral capture cross-sections and band offsets. The importance of atomically abrupt interfaces and the difficulties to obtain them on pyramidally textured c-Si is studied in combination with transmission electron microscopy. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Optical bandgap of ultra-thin amorphous silicon films deposited on crystalline silicon by PECVD

    Directory of Open Access Journals (Sweden)

    Yaser Abdulraheem

    2014-05-01

    Full Text Available An optical study based on spectroscopic ellipsometry, performed on ultrathin hydrogenated amorphous silicon (a-Si:H layers, is presented in this work. Ultrathin layers of intrinsic amorphous silicon have been deposited on n-type mono-crystalline silicon (c-Si wafers by plasma enhanced chemical vapor deposition (PECVD. The layer thicknesses along with their optical properties –including their refractive index and optical loss- were characterized by spectroscopic ellipsometry (SE in a wavelength range from 250 nm to 850 nm. The data was fitted to a Tauc-Lorentz optical model and the fitting parameters were extracted and used to compute the refractive index, extinction coefficient and optical bandgap. Furthermore, the a-Si:H film grown on silicon was etched at a controlled rate using a TMAH solution prepared at room temperature. The optical properties along with the Tauc-Lorentz fitting parameters were extracted from the model as the film thickness was reduced. The etch rate for ultrathin a-Si:H layers in TMAH at room temperature was found to slow down drastically as the c-Si interface is approached. From the Tauc-Lorentz parameters obtained from SE, it was found that the a-Si film exhibited properties that evolved with thickness suggesting that the deposited film is non-homogeneous across its depth. It was also found that the degree of crystallinity and optical (Tauc bandgap increased as the layers were reduced in thickness and coming closer to the c-Si substrate interface, suggesting the presence of nano-structured clusters mixed into the amorphous phase for the region close to the crystalline silicon substrate. Further results from Atomic Force Microscopy and Transmission Electron Microscopy confirmed the presence of an interfacial transitional layer between the amorphous film and the underlying substrate showing silicon nano-crystalline enclosures that can lead to quantum confinement effects. Quantum confinement is suggested to be the cause

  8. Optical bandgap of ultra-thin amorphous silicon films deposited on crystalline silicon by PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Abdulraheem, Yaser, E-mail: yaser.abdulraheem@kuniv.edu.kw [Electrical Engineering Department, College of Engineering and Petroleum, Kuwait University. P.O. Box 5969, 13060 Safat (Kuwait); Gordon, Ivan; Bearda, Twan; Meddeb, Hosny; Poortmans, Jozef [IMEC, Kapeldreef 75, 3001, Leuven (Belgium)

    2014-05-15

    An optical study based on spectroscopic ellipsometry, performed on ultrathin hydrogenated amorphous silicon (a-Si:H) layers, is presented in this work. Ultrathin layers of intrinsic amorphous silicon have been deposited on n-type mono-crystalline silicon (c-Si) wafers by plasma enhanced chemical vapor deposition (PECVD). The layer thicknesses along with their optical properties –including their refractive index and optical loss- were characterized by spectroscopic ellipsometry (SE) in a wavelength range from 250 nm to 850 nm. The data was fitted to a Tauc-Lorentz optical model and the fitting parameters were extracted and used to compute the refractive index, extinction coefficient and optical bandgap. Furthermore, the a-Si:H film grown on silicon was etched at a controlled rate using a TMAH solution prepared at room temperature. The optical properties along with the Tauc-Lorentz fitting parameters were extracted from the model as the film thickness was reduced. The etch rate for ultrathin a-Si:H layers in TMAH at room temperature was found to slow down drastically as the c-Si interface is approached. From the Tauc-Lorentz parameters obtained from SE, it was found that the a-Si film exhibited properties that evolved with thickness suggesting that the deposited film is non-homogeneous across its depth. It was also found that the degree of crystallinity and optical (Tauc) bandgap increased as the layers were reduced in thickness and coming closer to the c-Si substrate interface, suggesting the presence of nano-structured clusters mixed into the amorphous phase for the region close to the crystalline silicon substrate. Further results from Atomic Force Microscopy and Transmission Electron Microscopy confirmed the presence of an interfacial transitional layer between the amorphous film and the underlying substrate showing silicon nano-crystalline enclosures that can lead to quantum confinement effects. Quantum confinement is suggested to be the cause of the observed

  9. Synthesis of silicon carbide at room temperature from colloidal suspensions of silicon dioxide and carbon nanotubes

    Science.gov (United States)

    Zhukalin, D. A.; Tuchin, A. V.; Kulikova, T. V.; Bityutskaya, L. A.

    2015-11-01

    Experimental and theoretical approaches were used for the investigation of mechanisms and conditions of self-organized nanostructures formation in the drying drop of the mixture of colloidal suspensions of nanoscale amorphous silicon dioxide and carbon nanotubes. The formation of rodlike structures with diameter 250-300nm and length ∼4pm was revealed. The diffraction analysis of the obtained nanostructures showed the formation of the silicon carbide phase at room temperature.

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

    Science.gov (United States)

    König, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

    2017-04-01

    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.

  11. Simulation and experimental verification of silicon dioxide deposition by PECVD

    Science.gov (United States)

    Xu, Qing; Li, Yu-Xing; Li, Xiao-Ning; Wang, Jia-Bin; Yang, Fan; Yang, Yi; Ren, Tian-Ling

    2017-02-01

    Deposition of silicon dioxide in high-density plasma is an important process in integrated circuit manufacturing. A software named CFD-ACE was used to simulate the mechanism of plasma in the chamber of plasma enhanced chemical vapor deposition (PECVD) system, and the evolution of the feature profile was simulated based on CFD-TOPO. Simulation and experiment of silicon dioxide that deposited in SiH4/N2O mixture by PECVD system was researched. The particle density, energy and angular distribution in the chamber were simulated and discussed. We also studied how the depth/width ratio affected the step coverage of the trench and analyzed the deposition rate of silicon dioxide on the feature scale. X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition of thin films. Images of the feature profiles were taken by scanning electron microscope (SEM). The simulation results were in good agreement with experimental, which could guide the semiconductor device manufacture.

  12. Continuous flow ink etching for direct micropattern of silicon dioxide

    Science.gov (United States)

    Xing, Jiyao; Rong, Weibin; Wang, Lefeng; Sun, Lining

    2016-07-01

    A continuous flow ink etching (CFIE) method is presented to directly create micropatterns on a 60 nm thick silicon dioxide (SiO2) layer. This technique employs a micropipette filled with potassium bifluoride (KHF2) aqueous solution to localize SiO2 dissolution in the vicinity of the micropipette tip. Both dot and line features with well-defined edges were fabricated and used as hardmasks for silicon etching. The linear density of etchant ink deposited on the SiO2 can be used to regulate the depth, width and 2D morphology of the line pattern. The characterization of CFIE including the resolution (about 4 μm), reproducibility and capability to form complex structures are reported. This technique provides a simple and flexible alternative to generate the SiO2 hardmask for silicon microstructure fabrication.

  13. Influence of porous silicon formation on the performance of multi-crystalline silicon solar cells

    Indian Academy of Sciences (India)

    M Saad; M Naddaf

    2015-06-01

    The effect of formation of porous silicon on the performance of multi-crystalline silicon (mc-Si) solar cells is presented. Surface treatment of mc-Si solar cells was performed by electrochemical etching in HF-based solution. The effect of etching is viewed through scanning electron microscope (SEM) photographs that indicated the formation of a porous layer on the surface. Total reflection spectroscopy measurements on solar cells revealed reduced reflection after etching. In order to demonstrate the effect of this porous layer on the solar cell performance, illumination-dependent – characteristics and spectral response measurements were performed and analysed before and after etching. At all illumination intensities, short-circuit current density and open-circuit voltage values for the etched solar cell were higher than those before etching, whereas fill factor values were lower for the etched cell at high illumination intensities. An interpretation of these findings is presented.

  14. Effective surface passivation of p-type crystalline silicon with silicon oxides formed by light-induced anodisation

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jie, E-mail: j.cui@unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia); Grant, Nicholas [Centre for Sustainable Energy Systems, Australian National University, Canberra, A.C.T. 0200 (Australia); Lennon, Alison [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia)

    2014-12-30

    Highlights: • The surface passivation by anodic SiO{sub 2} formed by light-induced anodisation is investigated. • The anodic SiO{sub 2} grows lower temperatures with shorter growth times. After annealing in oxygen and then forming gas the effective minority carrier lifetime is increased to 150 μs. • It shows a very low positive Q{sub eff} of 3.4 × 10{sup 11} cm{sup −2}, a moderate D{sub it} of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. • It has a very low leakage current density suggesting its application in solar cell as a functional dielectric. - Abstract: Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO{sub 2}) was investigated. The anodic SiO{sub 2} was grown by light-induced anodisation (LIA) in diluted sulphuric acid at room temperature, a process that is significantly less-expensive than thermal oxidation which is widely-used in silicon solar cell fabrication. After annealing in oxygen and then forming gas at 400 °C for 30 min, the effective minority carrier lifetime of 3–5 Ω cm, boron-doped Czochralski silicon wafers with a phosphorus-doped 80 Ω/□ emitter and a LIA anodic SiO{sub 2} formed on the p-type surface was increased by two orders of magnitude to 150 μs. Capacitance–voltage measurements demonstrated a very low positive charge density of 3.4 × 10{sup 11} cm{sup −2} and a moderate density of interface states of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. This corresponded to a silicon surface recombination velocity of 62 cm s{sup −1}, which is comparable with values reported for other anodic SiO{sub 2} films, which required higher temperatures and longer growth times, and significantly lower than oxides grown by chemical vapour deposition techniques. Additionally, a very low leakage current density of 3.5 × 10{sup −10} and 1.6 × 10{sup −9} A cm{sup −2} at 1 and −1 V, respectively, was measured for LIA SiO{sub 2} suggesting its potential application as insulation layer in

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

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, H.

    2011-03-01

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

  16. Performance analysis of field exposed single crystalline silicon modules

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, O.S.; Saurabh, Sriparn; Shil, S.K.; Pant, P.C.; Kumar, Rajesh; Kumar, Arun; Bandopadhyay, Bibek [Solar Energy Centre, Ministry of New and Renewable Energy, Block-14, CGO Complex, Lodhi Road, New Delhi - 110003 (India)

    2010-09-15

    This paper presents results on the field performance degradation of mono-crystalline silicon PV modules from 11 PV module manufacturers under identical field conditions. The modules were installed in both fixed tilt and manual tracking modes. The data were monitored using a CR23X Data logger and I-V curves were taken using SPI 240A Sun simulator. The performance parameters analyzed are V{sub oc}, I{sub sc}, P{sub max}, I{sub mp}, V{sub mp} and the fill factor, as a function of time of field exposure. Qualitative studies are made on physically visible defects such as EVA coloration, cell de-laminations, corrosion of solar cell grid, corrosion of end strip connected in the terminal box, failure of by-pass diode, detachment of the terminal box, tearing of tedlar sheet, etc. The effect of field exposure on the performance parameters indicates that the qualification standard (s) needs to be reviewed and revised if the modules are to perform for {proportional_to}20 years under actual field conditions in India. (author)

  17. Fracture of crystalline silicon nanopillars during electrochemical lithium insertion

    KAUST Repository

    Lee, S. W.

    2012-02-27

    From surface hardening of steels to doping of semiconductors, atom insertion in solids plays an important role in modifying chemical, physical, and electronic properties of materials for a variety of applications. High densities of atomic insertion in a solid can result in dramatic structural transformations and associated changes in mechanical behavior: This is particularly evident during electrochemical cycling of novel battery electrodes, such as alloying anodes, conversion oxides, and sulfur and oxygen cathodes. Silicon, which undergoes 400% volume expansion when alloying with lithium, is an extreme case and represents an excellent model system for study. Here, we show that fracture locations are highly anisotropic for lithiation of crystalline Si nanopillars and that fracture is strongly correlated with previously discovered anisotropic expansion. Contrary to earlier theoretical models based on diffusion-induced stresses where fracture is predicted to occur in the core of the pillars during lithiation, the observed cracks are present only in the amorphous lithiated shell. We also show that the critical fracture size is between about 240 and 360 nm and that it depends on the electrochemical reaction rate.

  18. Threshold for permanent refractive index change in crystalline silicon by femtosecond laser irradiation

    Science.gov (United States)

    Bachman, D.; Chen, Z.; Fedosejevs, R.; Tsui, Y. Y.; Van, V.

    2016-08-01

    An optical damage threshold for crystalline silicon from single femtosecond laser pulses was determined by detecting a permanent change in the refractive index of the material. This index change could be detected with unprecedented sensitivity by measuring the resonant wavelength shift of silicon integrated optics microring resonators irradiated with femtosecond laser pulses at 400 nm and 800 nm wavelengths. The threshold for permanent index change at 400 nm wavelength was determined to be 0.053 ± 0.007 J/cm2, which agrees with previously reported threshold values for femtosecond laser modification of crystalline silicon. However, the threshold for index change at 800 nm wavelength was found to be 0.044 ± 0.005 J/cm2, which is five times lower than the previously reported threshold values for visual change on the silicon surface. The discrepancy is attributed to possible modification of the crystallinity of silicon below the melting temperature that has not been detected before.

  19. Simultaneous removal of tetracycline hydrochloride and As(III) using poorly-crystalline manganese dioxide.

    Science.gov (United States)

    Wang, Huawei; Zhang, Daoyong; Mou, Shuyong; Song, Wenjuan; Al-Misned, Fahad A; Golam Mortuza, M; Pan, Xiangliang

    2015-10-01

    Simultaneous removal of antibiotic tetracycline hydrochloride (TC) and As(III) by poorly-crystalline Mn dioxide was investigated. TC and As(III) can be effectively oxidized and removed by MnO2. High concentrations of TC and As(III) competed with each other for oxidation or adsorption sites on MnO2 and thus affected their removal efficiency. The intermediates and products of TC after reaction with poorly-crystalline manganese dioxide were identified by LC-ESI-MS (liquid chromatography-electrospray ionization-mass spectrometry), and the decomposition pathways of TC by MnO2 were proposed. This study is helpful for understanding the importance of environmental Mn dioxides in the decontamination of combined pollution by organic pollutants and metal(loid)s. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. High-flux solar furnace processing of crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsuo, Y.S.; Pitts, J.R. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Menna, P. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)]|[ENEA-Centro Ricerche Fotovoltaiche, Portici 80055 (Italy); Landry, M.D. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Gee, J.M. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)]|[Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Ciszek, T.F. [National Renewable Energy Laboratory, Golden, Colorado, 80401 (United States)

    1997-02-01

    We studied the processing of crystalline-silicon solar cells using a 10-kW, high-flux solar furnace (HFSF). Major findings of this study include: (1) hydrogenated amorphous silicon films deposited on glass substrates can be converted to microcrystalline silicon by solid-phase crystallization in 5 seconds or less in the HFSF; (2) the presence of concentrated sunlight enhances the diffusion of phosphorus into silicon from a spin-on dopant source; (3) the combination of a porous-silicon surface layer and photo-enhanced impurity diffusion is very effective in gettering impurities from a metallurgical-grade silicon wafer or thin-layer silicon deposited using liquid-phase epitaxy; (4) a 14.1{percent}-efficient crystalline-silicon solar cell with an area of 4.6cm{sup 2} was fabricated using the HFSF for simultaneous diffusion of front n{sup +}-p and back p-p{sup +} junctions; and (5) we have shown that the HFSF can be used to texture crystalline-silicon surfaces and to anneal metal contacts printed on a silicon solar cell. {copyright} {ital 1997 American Institute of Physics.}

  1. High-flux solar furnace processing of crystalline silicon solar cells

    Science.gov (United States)

    Tsuo, Y. S.; Pitts, J. R.; Menna, P.; Landry, M. D.; Gee, J. M.; Ciszek, T. F.

    1997-02-01

    We studied the processing of crystalline-silicon solar cells using a 10-kW, high-flux solar furnace (HFSF). Major findings of this study include: (1) hydrogenated amorphous silicon films deposited on glass substrates can be converted to microcrystalline silicon by solid-phase crystallization in 5 seconds or less in the HFSF; (2) the presence of concentrated sunlight enhances the diffusion of phosphorus into silicon from a spin-on dopant source; (3) the combination of a porous-silicon surface layer and photo-enhanced impurity diffusion is very effective in gettering impurities from a metallurgical-grade silicon wafer or thin-layer silicon deposited using liquid-phase epitaxy; (4) a 14.1%-efficient crystalline-silicon solar cell with an area of 4.6 cm2 was fabricated using the HFSF for simultaneous diffusion of front n+-p and back p-p+ junctions; and (5) we have shown that the HFSF can be used to texture crystalline-silicon surfaces and to anneal metal contacts printed on a silicon solar cell.

  2. Repulsive Casimir force between silicon dioxide and superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Phan, Anh D. [Department of Physics, University of South Florida, Tampa, Florida (United States); Viet, N.A. [Institute of Physics, Badinh, Hanoi (Viet Nam)

    2012-06-15

    We present a detailed investigation of the Casimir interaction between the superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (BSCCO) and silicon dioxide with bromobenzene present in between. We found that the dispersion force is repulsive and the magnitude of the force can be changed by varying the thickness of the object and the temperature. The repulsive force would provide a method to deal with stiction problems and provide much significant from the practical point of view. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Formation of thin-film crystalline silicon on glass observed by in-situ XRD

    NARCIS (Netherlands)

    Westra, J.M.; Vavrunkova, V.; Sutta, P.; Van Swaaij, R.A.C.M.M.; Zeman, M.

    2010-01-01

    Thin-film poly-crystalline silicon (poly c-Si) on glass obtained by crystallization of an amorphous silicon (a-Si) film is a promising material for low cost, high efficiency solar cells. Our approach to obtain this material is to crystallize a-Si films on glass by solid phase crystallization (SPC).

  4. Hopping Precession of Molecules in Crystalline Carbon Dioxide Films

    Science.gov (United States)

    Krainyukova, Nina; Kuchta, Bogdan

    2016-11-01

    We report a low-temperature transmission high-energy electron diffraction study of solid carbon dioxide films in the temperature range 15-87 K. The precise analysis of the experimental diffraction intensities shows that molecular axes noticeably deviate from the cubic space diagonals of the Paoverline{3} structure. The molecular tips tend to be oriented toward the empty spaces between two molecules in the nearest basal planes. Nevertheless, the crystal structure is still identified as Paoverline{3} but with 24 equivalent positions for oxygen atoms instead of 8 positions as it was thought before. We have shown that the relevant maximal angle deviations in the selected directions could be as big as ˜ 30° at the lowest temperatures and they decrease at higher temperature. This results in hopping precession of molecules instead of simple librations.

  5. Hopping Precession of Molecules in Crystalline Carbon Dioxide Films

    Science.gov (United States)

    Krainyukova, Nina; Kuchta, Bogdan

    2017-04-01

    We report a low-temperature transmission high-energy electron diffraction study of solid carbon dioxide films in the temperature range 15-87 K. The precise analysis of the experimental diffraction intensities shows that molecular axes noticeably deviate from the cubic space diagonals of the Paoverline{3} structure. The molecular tips tend to be oriented toward the empty spaces between two molecules in the nearest basal planes. Nevertheless, the crystal structure is still identified as Paoverline{3} but with 24 equivalent positions for oxygen atoms instead of 8 positions as it was thought before. We have shown that the relevant maximal angle deviations in the selected directions could be as big as {˜ } 30° at the lowest temperatures and they decrease at higher temperature. This results in hopping precession of molecules instead of simple librations.

  6. Current induced polycrystalline-to-crystalline transformation in vanadium dioxide nanowires

    Science.gov (United States)

    Jeong, Junho; Yong, Zheng; Joushaghani, Arash; Tsukernik, Alexander; Paradis, Suzanne; Alain, David; Poon, Joyce K. S.

    2016-11-01

    Vanadium dioxide (VO2) exhibits a reversible insulator-metal phase transition that is of significant interest in energy-efficient nanoelectronic and nanophotonic devices. In these applications, crystalline materials are usually preferred for their superior electrical transport characteristics as well as spatial homogeneity and low surface roughness over the device area for reduced scattering. Here, we show applied electrical currents can induce a permanent reconfiguration of polycrystalline VO2 nanowires into crystalline nanowires, resulting in a dramatically reduced hysteresis across the phase transition and reduced resistivity. Low currents below 3 mA were sufficient to cause the local temperature in the VO2 to reach about 1780 K to activate the irreversible polycrystalline-to-crystalline transformation. The crystallinity was confirmed by electron microscopy and diffraction analyses. This simple yet localized post-processing of insulator-metal phase transition materials may enable new methods of studying and fabricating nanoscale structures and devices formed from these materials.

  7. Method of forming crystalline silicon devices on glass

    Science.gov (United States)

    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.

  8. Dynamics of interstitial hydrogen molecules in crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Estreicher, S.K.; Wells, K. [Department of Physics, Texas Tech University, Lubbock, TX (United States); Fedders, P.A. [Department of Physics, Washington University, St. Louis, MO (United States); Ordejon, Pablo [Institut de Ciencia de Materiales de Barcelona, CSIC, Campus de la UAB, Bellaterra, Barcelona (Spain)

    2001-07-23

    The static and dynamic properties of interstitial H{sub 2}, HD and D{sub 2} molecules in crystalline silicon are obtained from ab initio molecular-dynamics simulations with atomic-like basis sets. The static (T=0) calculations agree with those of most other authors: the centre of mass (CM) of H{sub 2} is at the tetrahedral interstitial (T) site, the molecule is a nearly-free rotator, and the activation energy for diffusion is 0.90 eV. However, these results fail to explain a number of experimental observations, such as why H{sub 2} is infrared (IR) active, why the expected ortho/para splitting is not present, why the symmetry is C{sub 1}, why the piezospectroscopic tensors of H{sub 2} and D{sub 2} are identical or why the exposure to an H/D mix results in a single HD line which is not only at the wrong place but also much weaker than expected. In the present work, we extend the static calculations to include the constant-temperature dynamics for H{sub 2} in Si. At T>0 K, the CM of the molecule no longer remains at the T site. Instead, H{sub 2} 'bounces' off the walls of its tetrahedral cage and exchanges energy with the host crystal. The average position of the CM is away from the T site along <100>. Under uniaxial stress, the CM shifts off that axis and the molecule has C{sub 1} symmetry. The H-H stretch frequency calculated from the Fourier transform of the v-v autocorrelation function is close to the measured one. Since the potential energy experienced by H{sub 2} in Si near the T site is very flat, we argue that H{sub 2} should be a nearly free quantum mechanical rotator. Up to room temperature, only the j=0 and j=1 rotational states are occupied, H{sub 2} resembles a sphere rather than a dumbbell, the symmetry is determined by the position of the CM and HD is equivalent to DH in any symmetry. The rapid motion of the CM implies that an ortho-to-para transition will occur if a large magnetic moment is nearby. Several candidates are proposed. Since

  9. Gettering impurities from crystalline silicon by aluminum diffusion using a porous silicon layer

    Energy Technology Data Exchange (ETDEWEB)

    Khedher, N.; Hajji, M.; Bessais, B.; Ezzaouia, H.; Bennaceur, R. [Laboratoire des Applications Solaires, Institut National de Recherche Scientifique et Technique, BP. 95, Hammam Lif (Tunisia); Selmi, A. [Laboratoire de Physique des Semi-conducteurs, Faculte des Sciences de Monastir, 5000 Monastir (Tunisia)

    2005-06-01

    In this paper, we report a study on the possibility of gettering transition metal impurities from solar grade crystalline silicon (Si). Porous silicon layers were formed by the stain-etching method on both sides of the Si wafer. Aluminum diffusion was done throughout the PS layer in an infrared furnace under a (N{sub 2}/O{sub 2}) controlled atmosphere. This enables to getter eventual metal impurities towards the PS layer. The gettering effect was evaluated by measuring the majority carrier density and mobility and the minority carrier diffusion length (L{sub d}) of the Si substrate. For this purpose, Wander Pauw and Hall Effect measurements together with the Light Beam Induced Current (LBIC) technique were used. We noticed that the best gettering corresponds to a heat treatment at 850 C for 30 min; in that case an evident decrease of the majority carrier density and an enhancement of the mobility were observed. After gettering, we found an apparent improvement of the minority carrier diffusion length. These results give evidence of the effectiveness of external gettering treatments by combining (Al-PS) layer for an efficient gettering effect in solar grade monocrystalline Si. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Crystalline Silicon Solar Cells with Thin Silicon Passivation Film Deposited prior to Phosphorous Diffusion

    Directory of Open Access Journals (Sweden)

    Ching-Tao Li

    2014-01-01

    Full Text Available We demonstrate the performance improvement of p-type single-crystalline silicon (sc-Si solar cells resulting from front surface passivation by a thin amorphous silicon (a-Si film deposited prior to phosphorus diffusion. The conversion efficiency was improved for the sample with an a-Si film of ~5 nm thickness deposited on the front surface prior to high-temperature phosphorus diffusion, with respect to the samples with an a-Si film deposited on the front surface after phosphorus diffusion. The improvement in conversion efficiency is 0.4% absolute with respect to a-Si film passivated cells, that is, the cells with an a-Si film deposited on the front surface after phosphorus diffusion. The new technique provided a 0.5% improvement in conversion efficiency compared to the cells without a-Si passivation. Such performance improvements result from reduced surface recombination as well as lowered contact resistance, the latter of which induces a high fill factor of the solar cell.

  11. Influence of silicon dioxide capping layers on pore characteristics in nanocrystalline silicon membranes.

    Science.gov (United States)

    Qi, Chengzhu; Striemer, Christopher C; Gaborski, Thomas R; McGrath, James L; Fauchet, Philippe M

    2015-02-06

    Porous nanocrystalline silicon (pnc-Si) membranes are a new class of membrane material with promising applications in biological separations. Pores are formed in a silicon film sandwiched between nm thick silicon dioxide layers during rapid thermal annealing. Controlling pore size is critical in the size-dependent separation applications. In this work, we systematically studied the influence of the silicon dioxide capping layers on pnc-Si membranes. Even a single nm thick top oxide layer is enough to switch from agglomeration to pore formation after annealing. Both the pore size and porosity increase with the thickness of the top oxide, but quickly reach a plateau after 10 nm of oxide. The bottom oxide layer acts as a barrier layer to prevent the a-Si film from undergoing homo-epitaxial growth during annealing. Both the pore size and porosity decrease as the thickness of the bottom oxide layer increases to 100 nm. The decrease of the pore size and porosity is correlated with the increased roughness of the bottom oxide layer, which hinders nanocrystal nucleation and nanopore formation.

  12. Activity of formaldehyde dehydrogenase on titanium dioxide films with different crystallinities

    Science.gov (United States)

    Nakamura, Hitomi; Kato, Katsuya; Masuda, Yoshitake; Kato, Kazumi

    2015-02-01

    Many biosensors have been developed and used in recent years, and to enhance the sensitivity and stability of enzyme biosensors, immobilization of the enzymes on material surfaces is a necessary and important step. Therefore, there has been considerable interest in understanding how material interfaces affect enzyme adsorption. In this study, the influence of the crystallinity of titanium dioxide (TiO2) films on the quantity and activity of the immobilized enzyme, i.e., formaldehyde dehydrogenase (FDH), was investigated. It was found that TiO2 films with high crystallinity, which were annealed at 550 °C, showed higher enzyme immobilization and activity compared with the non-annealed TiO2 film. These results suggest that the activity of enzymes could be affected by the crystallinity of surface materials.

  13. Optical gain and stimulated emission in periodic nanopatterned crystalline silicon.

    Science.gov (United States)

    Cloutier, Sylvain G; Kossyrev, Pavel A; Xu, Jimmy

    2005-12-01

    Persistent efforts have been made to achieve efficient light emission from silicon in the hope of extending the reach of silicon technology into fully integrated optoelectronic circuits, meeting the needs for high-bandwidth intrachip and interchip connects. Enhanced light emission from silicon is known to be theoretically possible, enabled mostly through quantum-confinement effects. Furthermore, Raman-laser conversion was demonstrated in silicon waveguides. Here we report on optical gain and stimulated emission in uniaxially nanopatterned silicon-on-insulator using a nanopore array as an etching mask. In edge-emission measurements, we observed threshold behaviour, optical gain, longitudinal cavity modes and linewidth narrowing, along with a collimated far-field pattern, all indicative of amplification and stimulated emission. The sub-bandgap 1,278 nm emission peak is attributed to A-centre mediated phononless direct recombination between trapped electrons and free holes. The controlled nanoscale silicon engineering, combined with the low material loss in this sub-bandgap spectral range and the long electron lifetime in such A-type trapping centres, gives rise to the measured optical gain and stimulated emission and provides a new pathway to enhance light emission from silicon.

  14. Molecular dynamics simulations on surface properties of silicon dioxide melts

    CERN Document Server

    Röder, A

    2000-01-01

    In the present thesis the surface properties of a silicon dioxide melt were studied. As first systems drops (i.e. sytems without periodic boundary conditions) of N=432, 1536, as well as 4608 atoms were considered. The second analyzed geometry corresponds to that of a thin film, i. e. periodic boundary conditions in x- and y-direction were present, while in z-direction one had a free surface. In this case a system of N=1152 atoms was considered. As model potential the two-body potential proposed by Beest, Kramer, and van Santen was applied. For both geometries five temperatures were considered, which lied in the range of 3000 K

  15. Effect of silicon solar cell processing parameters and crystallinity on mechanical strength

    Energy Technology Data Exchange (ETDEWEB)

    Popovich, V.A.; Yunus, A.; Janssen, M.; Richardson, I.M. [Delft University of Technology, Department of Materials Science and Engineering, Delft (Netherlands); Bennett, I.J. [Energy Research Centre of the Netherlands, Solar Energy, PV Module Technology, Petten (Netherlands)

    2011-01-15

    Silicon wafer thickness reduction without increasing the wafer strength leads to a high breakage rate during subsequent handling and processing steps. Cracking of solar cells has become one of the major sources of solar module failure and rejection. Hence, it is important to evaluate the mechanical strength of solar cells and influencing factors. The purpose of this work is to understand the fracture behavior of silicon solar cells and to provide information regarding the bending strength of the cells. Triple junctions, grain size and grain boundaries are considered to investigate the effect of crystallinity features on silicon wafer strength. Significant changes in fracture strength are found as a result of metallization morphology and crystallinity of silicon solar cells. It is observed that aluminum paste type influences the strength of the solar cells. (author)

  16. Preparation and single molecule structure of electroactive polysilane end-grafted on a crystalline silicon surface

    Science.gov (United States)

    Furukawa, Kazuaki; Ebata, Keisuke

    2000-12-01

    Electrically active polysilanes of poly(methylphenylsilane) (PMPS) and poly[bis(p-n-butylphenyl)silane] (PBPS), which are, respectively, known as a good hole transporting material and a near-ultraviolet electroluminescent material, are end-grafted directly on a crystalline silicon surface. The single polysilane molecules are clearly distinguished one from the other on the surface by means of atomic force microscopy observations. End-grafted single molecules of PMPS are observed as dots while end-grafted PBPS appear as worms extending for more than 100 nm on the crystalline silicon surface.

  17. Low-temperature deposition of crystalline silicon nitride nanoparticles by hot-wire chemical vapor deposition

    Science.gov (United States)

    Kim, Chan-Soo; Youn, Woong-Kyu; Lee, Dong-Kwon; Seol, Kwang-Soo; Hwang, Nong-Moon

    2009-07-01

    The nanocrystalline alpha silicon nitride (α-Si 3N 4) was deposited on a silicon substrate by hot-wire chemical vapor deposition at the substrate temperature of 700 °C under 4 and 40 Torr at the wire temperatures of 1430 and 1730 °C, with a gas mixture of SiH 4 and NH 3. The size and density of crystalline nanoparticles on the substrate increased with increasing wire temperature. With increasing reactor pressure, the crystallinity of α-Si 3N 4 nanoparticles increased, but the deposition rate decreased.

  18. Reaction Front Evolution during Electrochemical Lithiation of Crystalline Silicon Nanopillars

    KAUST Repository

    Lee, Seok Woo

    2012-12-01

    The high theoretical specific capacity of Si as an anode material is attractive in lithium-ion batteries, although the issues caused by large volume changes during cycling have been a major challenge. Efforts have been devoted to understanding how diffusion-induced stresses cause fracture, but recent observations of anisotropic volume expansion in single-crystalline Si nanostructures require new theoretical considerations of expansion behavior during lithiation. Further experimental investigation is also necessary to better understand the anisotropy of the lithiation process. Here, we present a method to reveal the crystalline core of partially lithiated Si nanopillars with three different crystallographic orientations by using methanol to dissolve the Li atoms from the amorphous Li-Si alloy. The exposed crystalline cores have flat {110} surfaces at the pillar sidewalls; these surfaces represent the position of the reaction front between the crystalline core and the amorphous Li-Si alloy. It was also found that an amorphous Si structure remained on the flat surfaces of the crystalline core after dissolution of the Li, which was presumed to be caused by the accumulation of Si atoms left over from the removal of Li from the Li-Si alloy. © 2012 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim.

  19. Physics and technology of amorphous-crystalline heterostructure silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sark, Wilfried G.J.H.M. van [Utrecht Univ. (Netherlands). Copernicus Institute, Science Technology and Society; Roca, Francesco [Unita Tecnologie Portici, Napoli (Italy). ENEA - Agenzia Nazionale per le Nuove Tecnologie, l' Energia e lo Sviluppo Economico Sostenibile; Korte, Lars [Helmholtz-Zentrum Berlin fuer Materialien und Energie (Germany). Inst. Silizium-Photovoltaik

    2012-07-01

    The challenge of developing photovoltaic (PV) technology to a cost-competitive alternative for established energy sources can be achieved using simple, high-throughput mass-production compatible processes. Issues to be addressed for large scale PV deployment in large power plants or in building integrated applications are enhancing the performance of solar energy systems by increasing solar cell efficiency, using low amounts of materials which are durable, stable, and abundant on earth, and reducing manufacturing and installation cost. Today's solar cell multi-GW market is dominated by crystalline silicon (c-Si) wafer technology, however new cell concepts are entering the market. One very promising solar cell design to answer these needs is the silicon hetero-junction solar cell, of which the emitter and back surface field are basically produced by a low temperature growth of ultra-thin layers of amorphous silicon. In this design, amorphous silicon (a-Si:H) constitutes both ''emitter'' and ''base-contact/back surface field'' on both sides of a thin crystalline silicon wafer-base (c-Si) where the photogenerated electrons and holes are generated; at the same time, a Si:H passivates the c-Si surface. Recently, cell efficiencies above 23% have been demonstrated for such solar cells. In this book, the editors present an overview of the state-of-the-art in physics and technology of amorphous-crystalline heterostructure silicon solar cells. (orig.)

  20. Effect of Subgrains on the Performance of Mono-Like Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Su Zhou

    2013-01-01

    Full Text Available The application of Czochralski (Cz monocrystalline silicon material in solar cells is limited by its high cost and serious light-induced degradation. The use of cast multicrystalline silicon is also hindered by its high dislocation densities and high surface reflectance after texturing. Mono-like crystalline silicon is a promising material because it has the advantages of both mono- and multicrystalline silicon. However, when mono-like wafers are made into cells, the efficiencies of a batch of wafers often fluctuate within a wide range of >1% (absolute. In this work, mono-like wafers are classified by a simple process and fabricated into laser doping selective emitter cells. The effect and mechanism of subgrains on the performance of mono-like crystalline silicon solar cells are studied. The results show that the efficiency of mono-like crystalline silicon solar cells significantly depends on material defects that appear as subgrains on an alkaline textured surface. These subgrains have an almost negligible effect on the optical performance, shunt resistance, and junction recombination but significantly affect the minority carrier diffusion length and quantum efficiency within a long wavelength range. Finally, an average efficiency of 18.2% is achieved on wafers with hardly any subgrain but with a small-grain band.

  1. Method for fabricating transistors using crystalline silicon devices on glass

    Science.gov (United States)

    McCarthy, A.M.

    1997-09-02

    A method for fabricating transistors using single-crystal silicon devices on glass. This method overcomes the potential damage that may be caused to the device during high voltage bonding and employs a metal layer which may be incorporated as part of the transistor. This is accomplished such that when the bonding of the silicon wafer or substrate to the glass substrate is performed, the voltage and current pass through areas where transistors will not be fabricated. After removal of the silicon substrate, further metal may be deposited to form electrical contact or add functionality to the devices. By this method both single and gate-all-around devices may be formed. 13 figs.

  2. Clathrates and beyond: Low-density allotropy in crystalline silicon

    Science.gov (United States)

    Beekman, Matt; Wei, Kaya; Nolas, George S.

    2016-12-01

    In its common, thermodynamically stable state, silicon adopts the same crystal structure as diamond. Although only a few alternative allotropic structures have been discovered and studied over the past six decades, advanced methods for structure prediction have recently suggested a remarkably rich low-density phase space that has only begun to be explored. The electronic properties of these low-density allotropes of silicon, predicted by first-principles calculations, indicate that these materials could offer a pathway to improving performance and reducing cost in a variety of electronic and energy-related applications. In this focus review, we provide an introduction and overview of recent theoretical and experimental results related to low-density allotropes of silicon, highlighting the significant potential these materials may have for technological applications, provided substantial challenges to their experimental preparation can be overcome.

  3. Effect of Surface Treated Silicon Dioxide Nanoparticles on Some Mechanical Properties of Maxillofacial Silicone Elastomer

    Directory of Open Access Journals (Sweden)

    Sara M. Zayed

    2014-01-01

    Full Text Available Current materials used for maxillofacial prostheses are far from ideal and there is a need for novel improved materials which mimic as close as possible the natural behavior of facial soft tissues. This study aimed to evaluate the effect of adding different concentrations of surface treated silicon dioxide nanoparticles (SiO2 on clinically important mechanical properties of a maxillofacial silicone elastomer. 147 specimens of the silicone elastomer were prepared and divided into seven groups (n=21. One control group was prepared without nanoparticles and six study groups with different concentrations of nanoparticles, from 0.5% to 3% by weight. Specimens were tested for tear strength (ASTM D624, tensile strength (ASTM D412, percent elongation, and shore A hardness. SEM was used to assess the dispersion of nano-SiO2 within the elastomer matrix. Data were analyzed by one-way ANOVA and Scheffe test (α=0.05. Results revealed significant improvement in all mechanical properties tested, as the concentration of the nanoparticles increased. This was supported by the results of the SEM. Hence, it can be concluded that the incorporation of surface treated SiO2 nanoparticles at concentration of 3% enhanced the overall mechanical properties of A-2186 silicone elastomer.

  4. Photonic Properties of Er-Doped Crystalline Silicon

    NARCIS (Netherlands)

    Vinh, N. Q.; Ha, N. N.; T. Gregorkiewicz,

    2009-01-01

    During the last four decades, a remarkable research effort has been made to understand the physical properties of Si:Er material, as it is considered to be a promising approach towards improving the optical properties of crystalline Si. in this paper, we present a summary of the most important resul

  5. Sub-amorphous thermal conductivity in ultrathin crystalline silicon nanotubes.

    Science.gov (United States)

    Wingert, Matthew C; Kwon, Soonshin; Hu, Ming; Poulikakos, Dimos; Xiang, Jie; Chen, Renkun

    2015-04-08

    Thermal transport behavior in nanostructures has become increasingly important for understanding and designing next generation electronic and energy devices. This has fueled vibrant research targeting both the causes and ability to induce extraordinary reductions of thermal conductivity in crystalline materials, which has predominantly been achieved by understanding that the phonon mean free path (MFP) is limited by the characteristic size of crystalline nanostructures, known as the boundary scattering or Casimir limit. Herein, by using a highly sensitive measurement system, we show that crystalline Si (c-Si) nanotubes (NTs) with shell thickness as thin as ∼5 nm exhibit a low thermal conductivity of ∼1.1 W m(-1) K(-1). Importantly, this value is lower than the apparent boundary scattering limit and is even about 30% lower than the measured value for amorphous Si (a-Si) NTs with similar geometries. This finding diverges from the prevailing general notion that amorphous materials represent the lower limit of thermal transport but can be explained by the strong elastic softening effect observed in the c-Si NTs, measured as a 6-fold reduction in Young's modulus compared to bulk Si and nearly half that of the a-Si NTs. These results illustrate the potent prospect of employing the elastic softening effect to engineer lower than amorphous, or subamorphous, thermal conductivity in ultrathin crystalline nanostructures.

  6. Influence of Boron doping on micro crystalline silicon growth

    Institute of Scientific and Technical Information of China (English)

    Li Xin-Li; Wang Guo; Chen Yong-Sheng; Yang Shi-E; Gu Jin-Hua; Lu Jing-Xiao; Gao Xiao-Yong; Li Rui; Jiao Yue-Chao; Gao Hai-Bo

    2011-01-01

    Microcrystalline silicon (Ftc-Si:H) thin films with and without boron doping are deposited using the radio-frequency plasmsrenhanced chemical vapour deposition method. The surface roughness evolutions of the silicon thin films are investigated using ex situ spectroscopic ellipsometry and an atomic force microscope. It is shown that the growth exponent β and the roughness exponent a are about 0.369 and 0.95 for the undoped thin film,respectively. Whereas,for the boron-doped pc-Si:H thin film,βincreases to 0.534 and a decreases to 0.46 due to the shadowing effect.

  7. ULTRATHIN SILICON MEMBRANES TO STUDY SUPERCURRENT TRANSPORT IN CRYSTALLINE SEMICONDUCTORS

    NARCIS (Netherlands)

    VANHUFFELEN, WM; DEBOER, MJ; KLAPWIJK, TM

    1991-01-01

    We have developed a two-step anisotropic etching process to fabricate thin silicon membranes, used to study supercurrent transport in semiconductor coupled weak links. The process uses a shallow BF2+ implantation, and permits easy control of membrane thickness less-than-or-equal-to 100 nm. Prelimina

  8. Low-Roughness Plasma Etching of HgCdTe Masked with Patterned Silicon Dioxide

    Science.gov (United States)

    Ye, Z. H.; Hu, W. D.; Yin, W. T.; Huang, J.; Lin, C.; Hu, X. N.; Ding, R. J.; Chen, X. S.; Lu, W.; He, L.

    2011-08-01

    A novel mask technique utilizing patterned silicon dioxide films has been exploited to perform mesa etching for device delineation and electrical isolation of HgCdTe third-generation infrared focal-plane arrays (IRFPAs). High-density silicon dioxide films were deposited at temperature of 80°C, and a procedure for patterning and etching of HgCdTe was developed by standard photolithography and wet chemical etching. Scanning electron microscopy (SEM) showed that the surfaces of inductively coupled plasma (ICP) etched samples were quite clean and smooth. Root-mean-square (RMS) roughness characterized by atomic force microscopy (AFM) was less than 1.5 nm. The etching selectivity between a silicon dioxide film and HgCdTe in the samples masked with patterned silicon dioxide films was greater than 30:1. These results show that the new masking technique is readily available and promising for HgCdTe mesa etching.

  9. 76 FR 66748 - Crystalline Silicon Photovoltaic Cells and Modules From China; Institution of Antidumping and...

    Science.gov (United States)

    2011-10-27

    ... COMMISSION Crystalline Silicon Photovoltaic Cells and Modules From China; Institution of Antidumping and... indication that an industry in the United States is materially injured or threatened with material injury, or the establishment of an industry in the United States is materially retarded, by reason of imports...

  10. Conventional and 360 degree electron tomography of a micro-crystalline silicon solar cell

    DEFF Research Database (Denmark)

    Duchamp, Martial; Ramar, Amuthan; Kovács, András

    2011-01-01

    Bright-field (BF) and annular dark-field (ADF) electron tomography in the transmission electron microscope (TEM) are used to characterize elongated porous regions or cracks (simply referred to as cracks thereafter) in micro-crystalline silicon (μc-Si:H) solar cell. The limitations of inferring...

  11. COMBINED EFFECT OF MECHANICAL GROOVING AND STAIN-ETCHED SURFACE ON OPTICAL AND ELECTRICAL PROPERTIES OF CRYSTALLINE SILICON SUBSTRATES

    OpenAIRE

    AHMED ZARROUG; LOTFI DERBALI; RACHID OUERTANI; WISSEM DIMASSI; HATEM EZZAOUIA

    2014-01-01

    This paper investigates the combined effect of mechanical grooving and porous silicon (PS) on the front surface reflectance and the electronic properties of crystalline silicon substrates. Mechanical surface texturization leads to reduce the cell reflectance, enhance the light trapping and augment the carrier collection probability. PS was introduced as an efficient antireflective coating (ARC) onto the front surface of crystalline silicon solar cell. Micro-periodic V-shaped grooves were made...

  12. Threshold for permanent refractive index change in crystalline silicon by femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, D., E-mail: bachman@ualberta.ca; Fedosejevs, R.; Tsui, Y. Y.; Van, V. [Electrical and Computer Engineering Department, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Chen, Z. [Electrical and Computer Engineering Department, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-08-29

    An optical damage threshold for crystalline silicon from single femtosecond laser pulses was determined by detecting a permanent change in the refractive index of the material. This index change could be detected with unprecedented sensitivity by measuring the resonant wavelength shift of silicon integrated optics microring resonators irradiated with femtosecond laser pulses at 400 nm and 800 nm wavelengths. The threshold for permanent index change at 400 nm wavelength was determined to be 0.053 ± 0.007 J/cm{sup 2}, which agrees with previously reported threshold values for femtosecond laser modification of crystalline silicon. However, the threshold for index change at 800 nm wavelength was found to be 0.044 ± 0.005 J/cm{sup 2}, which is five times lower than the previously reported threshold values for visual change on the silicon surface. The discrepancy is attributed to possible modification of the crystallinity of silicon below the melting temperature that has not been detected before.

  13. Graphene Quantum Dot Layers with Energy-Down-Shift Effect on Crystalline-Silicon Solar Cells.

    Science.gov (United States)

    Lee, Kyung D; Park, Myung J; Kim, Do-Yeon; Kim, Soo M; Kang, Byungjun; Kim, Seongtak; Kim, Hyunho; Lee, Hae-Seok; Kang, Yoonmook; Yoon, Sam S; Hong, Byung H; Kim, Donghwan

    2015-09-02

    Graphene quantum dot (GQD) layers were deposited as an energy-down-shift layer on crystalline-silicon solar cell surfaces by kinetic spraying of GQD suspensions. A supersonic air jet was used to accelerate the GQDs onto the surfaces. Here, we report the coating results on a silicon substrate and the GQDs' application as an energy-down-shift layer in crystalline-silicon solar cells, which enhanced the power conversion efficiency (PCE). GQD layers deposited at nozzle scan speeds of 40, 30, 20, and 10 mm/s were evaluated after they were used to fabricate crystalline-silicon solar cells; the results indicate that GQDs play an important role in increasing the optical absorptivity of the cells. The short-circuit current density was enhanced by about 2.94% (0.9 mA/cm(2)) at 30 mm/s. Compared to a reference device without a GQD energy-down-shift layer, the PCE of p-type silicon solar cells was improved by 2.7% (0.4 percentage points).

  14. Crystalline-Amorphous Core−Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes

    KAUST Repository

    Cui, Li-Feng

    2009-01-14

    Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon\\'s large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline- amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li ions. We demonstrate here that these core-shell nanowires have high charge storage capacity (̃1000 mAh/g, 3 times of carbon) with ̃90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, ̃20 times of carbon at 1 h rate). © 2009 American Chemical Society.

  15. Comparison of Oxidative Stresses Mediated by Different Crystalline Forms and Surface Modification of Titanium Dioxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Karim Samy El-Said

    2015-01-01

    Full Text Available Titanium dioxide nanoparticles (TiO2 NPs are manufactured worldwide for use in a wide range of applications. There are two common crystalline forms of TiO2 anatase and rutile with different physical and chemical characteristics. We previously demonstrated that an increased DNA damage response is mediated by anatase crystalline form compared to rutile. In the present study, we conjugated TiO2 NPs with polyethylene glycol (PEG in order to reduce the genotoxicity and we evaluated some oxidative stress parameters to obtain information on the cellular mechanisms of DNA damage that operate in response to TiO2 NPs different crystalline forms exposure in hepatocarcinoma cell lines (HepG2. Our results indicated a significant increase in oxidative stress mediated by the anatase form of TiO2 NPs compared to rutile form. On the other hand, PEG modified TiO2 NPs showed a significant decrease in oxidative stress as compared to TiO2 NPs. These data suggested that the genotoxic potential of TiO2 NPs varies with crystalline form and surface modification.

  16. IR characterization of hydrogen in crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Stavola, M., E-mail: michael.stavola@Lehigh.ed [Department of Physics, Lehigh University, Bethlehem, PA 18015 (United States); Kleekajai, S.; Wen, L.; Peng, C. [Department of Physics, Lehigh University, Bethlehem, PA 18015 (United States); Yelundur, V.; Rohatgi, A. [School of Electrical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Carnel, L. [REC Wafer AS, NO-3908 Porsgrunn (Norway); Kalejs, J. [American Capital Energy, N. Chelmsford, MA 01863 (United States)

    2009-12-15

    Hydrogen is commonly introduced into silicon solar cells to reduce the deleterious effects of defects and to increase cell efficiency. A process that is widely used by industry to introduce hydrogen is by the post-deposition annealing of a hydrogen-rich SiN{sub x} layer that is used as an anti-reflection coating. A number of questions about this hydrogen introduction process and hydrogen's subsequent interactions with defects have proved difficult to address because of the low concentration of hydrogen that is introduced into the Si bulk. We have used the fundamental knowledge of hydrogenated defects that has been revealed by recent investigations of impurity-H complexes to develop strategies by which hydrogen in silicon can be detected by IR spectroscopy with high sensitivity. The introduction of hydrogen into Si by the post-deposition annealing of a SiN{sub x} coating has been investigated.

  17. RF Magnetron Sputtering Aluminum Oxide Film for Surface Passivation on Crystalline Silicon Wafers

    Directory of Open Access Journals (Sweden)

    Siming Chen

    2013-01-01

    Full Text Available Aluminum oxide films were deposited on crystalline silicon substrates by reactive RF magnetron sputtering. The influences of the deposition parameters on the surface passivation, surface damage, optical properties, and composition of the films have been investigated. It is found that proper sputtering power and uniform magnetic field reduced the surface damage from the high-energy ion bombardment to the silicon wafers during the process and consequently decreased the interface trap density, resulting in the good surface passivation; relatively high refractive index of aluminum oxide film is benefic to improve the surface passivation. The negative-charged aluminum oxide film was then successfully prepared. The surface passivation performance was further improved after postannealing by formation of an SiOx interfacial layer. It is demonstrated that the reactive sputtering is an effective technique of fabricating aluminum oxide surface passivation film for low-cost high-efficiency crystalline silicon solar cells.

  18. Novel Ag-doped glass frits for high-efficiency crystalline silicon solar cells.

    Science.gov (United States)

    Yuan, Sheng; Chen, Yongji; Mei, Zongwei; Zhang, Ming-Jian; Gao, Zhou; Wang, Xingbo; Jiang, Xing; Pan, Feng

    2017-06-06

    Glass frits play an important role in the front contact electrodes of crystalline silicon (c-Si) solar cells. In this work, we developed a novel glass frit by doping Ag into a glass frit in the process of high-temperature synthesis. When the Ag paste including this novel glass frit was used as the front contact electrode of silicon solar cells, the conversion efficiency of poly-crystalline silicon (pc-Si) solar cells was improved by 1.9% compared to the glass frit without Ag. Through SEM characterisation and calculation of series resistance, we further found that the interface between Ag and Si was improved and the contact resistance of Ag and Si was greatly reduced, which were believed to be responsible for the improvement of solar cell performance. This work shows great guidance significance to develop novel and highly efficient commercial glass frits applied in solar cells in the future.

  19. International round-robin inter-comparison of dye-sensitized and crystalline silicon solar cells

    Science.gov (United States)

    Chen, Chia-Yuan; Ahn, Seung Kyu; Aoki, Dasiuke; Kokubo, Junichi; Yoon, Kyung Hoon; Saito, Hidenori; Lee, Kyung Sik; Magaino, Shinichi; Takagi, Katsuhiko; Lin, Ling-Chuan; Lee, Kun-Mu; Wu, Chun-Guey; Zhou, Hong; Igari, Sanekazu

    2017-02-01

    An international round-robin inter-comparison of the spectral responsivity (SR) and current-voltage (I-V) characteristics for dye-sensitized solar cells (DSCs) and crystalline silicon solar cells is reported for the first time. The crystalline silicon cells with various spectral responsivities were also calibrated by AIST to validate this round-robin activity. On the basis of the remarkable consistency in Pmax (within ±1.4% among participants) and Isc (within ±1.2% compared to the primary calibration of AIST) of the silicon specimens, the discrepancy in the SR and photovoltaic parameters of five DSCs among three national laboratories can be verified and diagnosed. Recommendations about sample packages, SR and I-V measurement methods as well as the inter-comparison protocol for improving the performance characterization of the mesoscopic DSCs are presented according to the consolidated data and the experience of the participants.

  20. Synthetic osteogenic extracellular matrix formed by coated silicon dioxide nanosprings

    Directory of Open Access Journals (Sweden)

    Hass Jamie L

    2012-01-01

    Full Text Available Abstract Background The design of biomimetic materials that parallel the morphology and biology of extracellular matrixes is key to the ability to grow functional tissues in vitro and to enhance the integration of biomaterial implants into existing tissues in vivo. Special attention has been put into mimicking the nanostructures of the extracellular matrix of bone, as there is a need to find biomaterials that can enhance the bonding between orthopedic devices and this tissue. Methods We have tested the ability of normal human osteoblasts to propagate and differentiate on silicon dioxide nanosprings, which can be easily grown on practically any surface. In addition, we tested different metals and metal alloys as coats for the nanosprings in tissue culture experiments with bone cells. Results Normal human osteoblasts grown on coated nanosprings exhibited an enhanced rate of propagation, differentiation into bone forming cells and mineralization. While osteoblasts did not attach effectively to bare nanowires grown on glass, these cells propagated successfully on nanosprings coated with titanium oxide and gold. We observed a 270 fold increase in the division rate of osteoblasts when grow on titanium/gold coated nanosprings. This effect was shown to be dependent on the nanosprings, as the coating by themselves did not alter the growth rate of osteoblast. We also observed that titanium/zinc/gold coated nanosprings increased the levels of osteoblast production of alkaline phosphatase seven folds. This result indicates that osteoblasts grown on this metal alloy coated nanosprings are differentiating to mature bone making cells. Consistent with this hypothesis, we showed that osteoblasts grown on the same metal alloy coated nanosprings have an enhanced ability to deposit calcium salt. Conclusion We have established that metal/metal alloy coated silicon dioxide nanosprings can be used as a biomimetic material paralleling the morphology and biology of

  1. Sintering of nano crystalline silicon carbide doping with aluminium nitride

    Indian Academy of Sciences (India)

    M S Datta; A K Bandyopadhyay; B Chaudhuri

    2002-04-01

    Sinterable silicon carbide powders were prepared by attrition milling and chemical processing of an acheson type -SiC. Pressureless sintering of these powders was achieved by addition of aluminium nitride together with carbon. Nearly 99% sintered density was obtained. The mechanism of sintering was studied by scanning electron microscopy and transmission electron microscopy. This study shows that the mechanism is a solid sintering process.

  2. Amorphous Silicon Carbide Passivating Layers to Enable Higher Processing Temperature in Crystalline Silicon Heterojunction Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Boccard, Mathieu [Arizona State Univ., Mesa, AZ (United States); Holman, Zachary [Arizona State Univ., Mesa, AZ (United States)

    2015-04-06

    "Very efficient crystalline silicon (c-Si) solar cells have been demonstrated when thin layers of intrinsic and doped hydrogenated amorphous silicon (a-Si:H) are used for passivation and carrier selectivity in a heterojunction device. One limitation of this device structure is the (parasitic) absorption in the front passivation/collection a-Si:H layers; another is the degradation of the a-Si:H-based passivation upon temperature, limiting the post-processes to approximately 200°C thus restricting the contacting possibilities and potential tandem device fabrication. To alleviate these two limitations, we explore the potential of amorphous silicon carbide (a-SiC:H), a widely studied material in use in standard a-Si:H thin-film solar cells, which is known for its wider bandgap, increased hydrogen content and stronger hydrogen bonding compared to a-Si:H. We study the surface passivation of solar-grade textured n-type c-Si wafers for symmetrical stacks of 10-nm-thick intrinsic a-SiC:H with various carbon content followed by either p-doped or n-doped a-Si:H (referred to as i/p or i/n stacks). For both doping types, passivation (assessed through carrier lifetime measurements) is degraded by increasing the carbon content in the intrinsic a-SiC:H layer. Yet, this hierarchy is reversed after annealing at 350°C or more due to drastic passivation improvements upon annealing when an a-SiC:H layer is used. After annealing at 350°C, lifetimes of 0.4 ms and 2.0 ms are reported for i/p and i/n stacks, respectively, when using an intrinsic a-SiC:H layer with approximately 10% of carbon (initial lifetimes of 0.3 ms and 0.1 ms, respectively, corresponding to a 30% and 20-fold increase, respectively). For stacks of pure a-Si:H material the lifetimes degrade from 1.2 ms and 2.0 ms for i/p and i/n stacks, respectively, to less than 0.1 ms and 1.1 ms (12-fold and 2-fold decrease, respectively). For complete solar cells using pure a-Si:H i/p and i/n stacks, the open-circuit voltage (Voc

  3. N-type crystalline silicon films free of amorphous silicon deposited on glass by HCl addition using hot wire chemical vapour deposition.

    Science.gov (United States)

    Chung, Yung-Bin; Park, Hyung-Ki; Lee, Sang-Hoon; Song, Jean-Ho; Hwang, Nong-Moon

    2011-09-01

    Since n-type crystalline silicon films have the electric property much better than those of hydrogenated amorphous and microcrystalline silicon films, they can enhance the performance of advanced electronic devices such as solar cells and thin film transistors (TFTs). Since the formation of amorphous silicon is unavoidable in the low temperature deposition of microcrystalline silicon on a glass substrate at temperatures less than 550 degrees C in the plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition (HWCVD), crystalline silicon films have not been deposited directly on a glass substrate but fabricated by the post treatment of amorphous silicon films. In this work, by adding the HCl gas, amorphous silicon-free n-type crystalline silicon films could be deposited directly on a glass substrate by HWCVD. The resistivity of the n-type crystalline silicon film for the flow rate ratio of [HCl]/[SiH4] = 7.5 and [PH3]/[SiH4] = 0.042 was 5.31 x 10(-4) ohms cm, which is comparable to the resistivity 1.23 x 10(-3) ohms cm of films prepared by thermal annealing of amorphous silicon films. The absence of amorphous silicon in the film could be confirmed by high resolution transmission electron microscopy.

  4. Electrochemical removal of segregated silicon dioxide impurities from yttria stabilized zirconia surfaces at elevated temperatures

    DEFF Research Database (Denmark)

    Andersen, Thomas; Hansen, Karin Vels; Mogensen, Mogens Bjerg;

    2011-01-01

    Here we report on the electrochemical removal of segregated silicon dioxide impurities from Yttria Stabilized Zirconia (YSZ) surfaces at elevated temperatures studied under Ultra High Vacuum (UHV) conditions. YSZ single crystals were heated in vacuum by an applied 18kHz a.c. voltage using the ionic...... and XPS analysis. Silicon enrichment of the surface was only observed at oxygen and water vapor partial pressures above 25mbar and 10mbar, respectively. No silicon was observed on crystals annealed in vacuum and at oxygen and water vapor partial pressures below 10mbar. The YSZ seems to get partially...... electrochemically reduced by the a.c. voltage when no oxidation substances are present. The absence of silicon on the surfaces annealed in vacuum or at low oxygen or water vapor partial pressures was attributed to electrochemical reduction of silicon dioxide to volatile silicon monoxide on the YSZ surface...

  5. Etching Rate of Silicon Dioxide Using Chlorine Trifluoride Gas

    Science.gov (United States)

    Miura, Yutaka; Kasahara, Yu; Habuka, Hitoshi; Takechi, Naoto; Fukae, Katsuya

    2009-02-01

    The etching rate behavior of silicon dioxide (SiO2, fused silica) using chlorine trifluoride (ClF3) gas is studied at substrate temperatures between 573 and 1273 K at atmospheric pressure in a horizontal cold-wall reactor. The etching rate increases with the ClF3 gas concentration, and the overall reaction is recognized to be of the first order. The change of the etching rate with increasing substrate temperature is nonlinear, and the etching rate tends to approach a constant value at temperatures exceeding 1173 K. The overall rate constant is estimated by numerical calculation, taking into account the transport phenomena in the reactor, including the chemical reaction at the substrate surface. The activation energy obtained in this study is 45.8 kJ mol-1, and the rate constant is consistent with the measured etching rate behavior. A reactor system in which there is minimum etching of the fused silica chamber by ClF3 gas can be achieved using an IR lamp heating unit and a chamber cooling unit to maintain a sufficiently low temperature of the chamber wall.

  6. Rain Erosion Behavior of Silicon Dioxide Films Prepared on Sapphire

    Institute of Scientific and Technical Information of China (English)

    Liping FENG; Zhengtang LIU; Wenting LIU

    2005-01-01

    Silicon dioxide (SiO2) films were prepared on sapphire (α-Al2O3) by radio frequency magnetron reactive sputtering in order to in crease both transmission and rain erosion resistant performance of infrared domes of sapphire. Composition and structure of SiO2 films were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD),respectively. The transmittance of uncoated and coated sapphire was measured using a Fourier transform infrared(FTIR) spectrometer. Rain erosion tests of the uncoated and coated sapphire were performed at 211 m/s impact velocity with an exposure time ranging from 1 to 8 min on a whirling arm rig. Results show that the deposited films can greatly increase the transmission of sapphire in mid-wave IR. After rain erosion test, decreases in normalized transmission were less than 1% for designed SiO2 films and the SiO2 coating was strongly bonded to the sapphire substrate. In addition, sapphires coated with SiO2 films had a higher transmittance than uncoated ones after rain erosion.

  7. Revival of interband crystalline reflectance from nanocrystallites in porous silicon by immersion plating

    Energy Technology Data Exchange (ETDEWEB)

    Yamani, Z.; Alaql, A.; Therrien, J.; Nayfeh, O.; Nayfeh, M. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    1999-06-01

    We prepared porous silicon for which the UV reflectance (3.3{endash}6 eV) is nearly eliminated, and exhibits no features at the Si interband bulk transitions 3.3, 4.3, and 5.5 eV. Plating with a thin layer of copper is found to cause recovery of the UV bulk-like crystalline reflectance and interband resonances. This provides evidence that the loss of crystalline absorption is reversible and is not due to a permanent loss in the crystalline structure. This may relate to a recent model in which the optical activity of ultra small nanocrystallites is produced by a new Si{endash}Si crystalline configuration (or phase), distinct from but interconnected to the diamond-like configuration by a potential barrier. {copyright} {ital 1999 American Institute of Physics.}

  8. Biomimetic and plasmonic hybrid light trapping for highly efficient ultrathin crystalline silicon solar cells.

    Science.gov (United States)

    Zhang, Y; Jia, B; Gu, M

    2016-03-21

    Designing effective light-trapping structures for the insufficiently absorbed long-wavelength light in ultrathin silicon solar cells represents a key challenge to achieve low cost and highly efficient solar cells. We propose a hybrid structure based on the biomimetic silicon moth-eye structure combined with Ag nanoparticles to achieve advanced light trapping in 2 μm thick crystalline silicon solar cells approaching the Yablonovitch limit. By synergistically using the Mie resonances of the silicon moth-eye structure and the plasmonic resonances of the Ag nanoparticles, the integrated absorption enhancement achieved across the usable solar spectrum is 69% compared with the cells with the conventional light trapping design. This is significantly larger than both the silicon moth-eye structure (58%) and Ag nanoparticle (41%) individual light trapping. The generated photocurrent in the 2 μm thick silicon layer is as large as 33.4 mA/cm2, which is equivalent to that generated by a 30 μm single-pass absorption in the silicon. The research paves the way for designing highly efficient light trapping structures in ultrathin silicon solar cells.

  9. Advancements in n-Type Base Crystalline Silicon Solar Cells and Their Emergence in the Photovoltaic Industry

    Directory of Open Access Journals (Sweden)

    Atteq ur Rehman

    2013-01-01

    Full Text Available The p-type crystalline silicon wafers have occupied most of the solar cell market today. However, modules made with n-type crystalline silicon wafers are actually the most efficient modules up to date. This is because the material properties offered by n-type crystalline silicon substrates are suitable for higher efficiencies. Properties such as the absence of boron-oxygen related defects and a greater tolerance to key metal impurities by n-type crystalline silicon substrates are major factors that underline the efficiency of n-type crystalline silicon wafer modules. The bi-facial design of n-type cells with good rear-side electronic and optical properties on an industrial scale can be shaped as well. Furthermore, the development in the industrialization of solar cell designs based on n-type crystalline silicon substrates also highlights its boost in the contributions to the photovoltaic industry. In this paper, a review of various solar cell structures that can be realized on n-type crystalline silicon substrates will be given. Moreover, the current standing of solar cell technology based on n-type substrates and its contribution in photovoltaic industry will also be discussed.

  10. Advancements in n-type base crystalline silicon solar cells and their emergence in the photovoltaic industry.

    Science.gov (United States)

    ur Rehman, Atteq; Lee, Soo Hong

    2013-01-01

    The p-type crystalline silicon wafers have occupied most of the solar cell market today. However, modules made with n-type crystalline silicon wafers are actually the most efficient modules up to date. This is because the material properties offered by n-type crystalline silicon substrates are suitable for higher efficiencies. Properties such as the absence of boron-oxygen related defects and a greater tolerance to key metal impurities by n-type crystalline silicon substrates are major factors that underline the efficiency of n-type crystalline silicon wafer modules. The bi-facial design of n-type cells with good rear-side electronic and optical properties on an industrial scale can be shaped as well. Furthermore, the development in the industrialization of solar cell designs based on n-type crystalline silicon substrates also highlights its boost in the contributions to the photovoltaic industry. In this paper, a review of various solar cell structures that can be realized on n-type crystalline silicon substrates will be given. Moreover, the current standing of solar cell technology based on n-type substrates and its contribution in photovoltaic industry will also be discussed.

  11. Advancements in n-Type Base Crystalline Silicon Solar Cells and Their Emergence in the Photovoltaic Industry

    Science.gov (United States)

    ur Rehman, Atteq; Lee, Soo Hong

    2013-01-01

    The p-type crystalline silicon wafers have occupied most of the solar cell market today. However, modules made with n-type crystalline silicon wafers are actually the most efficient modules up to date. This is because the material properties offered by n-type crystalline silicon substrates are suitable for higher efficiencies. Properties such as the absence of boron-oxygen related defects and a greater tolerance to key metal impurities by n-type crystalline silicon substrates are major factors that underline the efficiency of n-type crystalline silicon wafer modules. The bi-facial design of n-type cells with good rear-side electronic and optical properties on an industrial scale can be shaped as well. Furthermore, the development in the industrialization of solar cell designs based on n-type crystalline silicon substrates also highlights its boost in the contributions to the photovoltaic industry. In this paper, a review of various solar cell structures that can be realized on n-type crystalline silicon substrates will be given. Moreover, the current standing of solar cell technology based on n-type substrates and its contribution in photovoltaic industry will also be discussed. PMID:24459433

  12. Photovoltaic solar panels of crystalline silicon: Characterization and separation.

    Science.gov (United States)

    Dias, Pablo Ribeiro; Benevit, Mariana Gonçalves; Veit, Hugo Marcelo

    2016-03-01

    Photovoltaic panels have a limited lifespan and estimates show large amounts of solar modules will be discarded as electronic waste in a near future. In order to retrieve important raw materials, reduce production costs and environmental impacts, recycling such devices is important. Initially, this article investigates which silicon photovoltaic module's components are recyclable through their characterization using X-ray fluorescence, X-ray diffraction, energy dispersion spectroscopy and atomic absorption spectroscopy. Next, different separation methods are tested to favour further recycling processes. The glass was identified as soda-lime glass, the metallic filaments were identified as tin-lead coated copper, the panel cells were made of silicon and had silver filaments attached to it and the modules' frames were identified as aluminium, all of which are recyclable. Moreover, three different components segregation methods have been studied. Mechanical milling followed by sieving was able to separate silver from copper while chemical separation using sulphuric acid was able to detach the semiconductor material. A thermo gravimetric analysis was performed to evaluate the use of a pyrolysis step prior to the component's removal. The analysis showed all polymeric fractions present degrade at 500 °C.

  13. Gettering effect in grain boundaries of multi-crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Nouri, H.; Bouaicha, M.; Ben Rabha, M.; Bessais, B. [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, Hammam-Lif 2050 (Tunisia)

    2012-10-15

    In this work, we analyze the effect of three gettering procedures on the variation of the grain boundaries (GBs) defect density in multicrystalline silicon (mc-Si). The effective defect density (N{sup B}) was calculated using a theoretical model where we consider the potential barrier induced by the GB as being due to structural defects and impurities. Results are compared to those obtained from C-V measurements. The potential barrier was evaluated from the dark current-voltage (I-V) characteristic performed across the GB. In addition to the Rapid Thermal Annealing (RTA), we use aluminum (Al) in the first gettering procedure, in the second we use porous silicon (PS), whereas in the third one, we realize a chemical damage (grooving). Mc-Si wafers were annealed in an infrared furnace in the same conditions, at temperatures ranging from 600 C to 1000 C (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Elastic behavior of amorphous-crystalline silicon nanocomposite: An atomistic view

    Science.gov (United States)

    Das, Suvankar; Dutta, Amlan

    2017-01-01

    In the context of mechanical properties, nanocomposites with homogeneous chemical composition throughout the matrix and the dispersed phase are of particular interest. In this study, the elastic moduli of amorphous-crystalline silicon nanocomposite have been estimated using atomistic simulations. A comparison with the theoretical model reveals that the elastic behavior is significantly influenced by the crystal-amorphous interphase. On observing the effect of volume-fraction of the crystalline phase, an anomalous trend for the bulk modulus is obtained. This phenomenon is attributed to the relaxation displacements of the amorphous atoms.

  15. Sprayed and Spin-Coated Multilayer Antireflection Coating Films for Nonvacuum Processed Crystalline Silicon Solar Cells

    OpenAIRE

    Abdullah Uzum; Masashi Kuriyama; Hiroyuki Kanda; Yutaka Kimura; Kenji Tanimoto; Hidehito Fukui; Taichiro Izumi; Tomitaro Harada; Seigo Ito

    2017-01-01

    Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm) was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fa...

  16. Characterization of heterojunctions in crystalline-silicon-based solar cells by internal photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, Isao; Yamanaka, Mitsuyuki; Kawanami, Hitoshi [Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, AIST Central-2, Tsukuba, Ibaraki 305-8568 (Japan)

    2009-06-15

    Internal photoemission (IPE) has been successfully applied to evaluate band offsets of heterojunctions (HJs) in crystalline silicon (c-Si)-based solar cells. Tunneling of carriers through the potential spike at HJ and the presence of a carrier conduction path in the wide-band-gap material of HJ can affect the IPE results. In other words, IPE measures the effective band discontinuity, including effects of the carrier conduction path. This feature of IPE is suited for the characterization of solar-cell structures. Results obtained for hydrogenated amorphous silicon/c-Si HJ and gallium phosphide/c-Si HJ are presented and discussed. (author)

  17. Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

    KAUST Repository

    Bahabry, R. R.

    2016-11-30

    We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.

  18. Silanization effect on the photoluminescence characteristics of crystalline and amorphous silicon nanoparticles.

    Science.gov (United States)

    Caregnato, Paula; Dell'Arciprete, Maria Laura; Gonzalez, Mónica Cristina

    2013-09-01

    Silicon nanoparticles synthesized by two different methods were surface modified with 3-mercaptopropyltrimethoxysilane. The particles of ~2 nm size exhibit photoluminescence (PL) in the UV-Vis range of the spectrum. The most intense PL band at 430 nm with an emission lifetime of 1-2 ns is attributed to the presence of the surface defects Si-O-Si, generated after anchoring the organic molecule onto the interface. The excitation-emission matrix of this band is essentially independent of the technique of synthesis, crystalline structure, and size of the silicon nanoparticles.

  19. Single crystalline silicon solar cells with rib structure

    Science.gov (United States)

    Yoshiba, Shuhei; Hirai, Masakazu; Abe, Yusuke; Konagai, Makoto; Ichikawa, Yukimi

    2017-02-01

    To improve the conversion efficiency of Si solar cells, we have developed a thin Si wafer-based solar cell that uses a rib structure. The open-circuit voltage of a solar cell is known to increase with deceasing wafer thickness if the cell is adequately passivated. However, it is not easy to handle very thin wafers because they are brittle and are subject to warpage. We fabricated a lattice-shaped rib structure on the rear side of a thin Si wafer to improve the wafer's strength. A silicon nitride film was deposited on the Si wafer surface and patterned to form a mask to fabricate the lattice-shaped rib, and the wafer was then etched using KOH to reduce the thickness of the active area, except for the rib region. Using this structure in a Si heterojunction cell, we demonstrated that a high open-circuit voltage (VOC) could be obtained by thinning the wafer without sacrificing its strength. A wafer with thickness of 30 μm was prepared easily using this structure. We then fabricated Si heterojunction solar cells using these rib wafers, and measured their implied VOC as a function of wafer thickness. The measured values were compared with device simulation results, and we found that the measured VOC agrees well with the simulated results. To optimize the rib and cell design, we also performed device simulations using various wafer thicknesses and rib dimensions.

  20. Single crystalline silicon solar cells with rib structure

    Directory of Open Access Journals (Sweden)

    Shuhei Yoshiba

    2017-02-01

    Full Text Available To improve the conversion efficiency of Si solar cells, we have developed a thin Si wafer-based solar cell that uses a rib structure. The open-circuit voltage of a solar cell is known to increase with deceasing wafer thickness if the cell is adequately passivated. However, it is not easy to handle very thin wafers because they are brittle and are subject to warpage. We fabricated a lattice-shaped rib structure on the rear side of a thin Si wafer to improve the wafer’s strength. A silicon nitride film was deposited on the Si wafer surface and patterned to form a mask to fabricate the lattice-shaped rib, and the wafer was then etched using KOH to reduce the thickness of the active area, except for the rib region. Using this structure in a Si heterojunction cell, we demonstrated that a high open-circuit voltage (VOC could be obtained by thinning the wafer without sacrificing its strength. A wafer with thickness of 30 μm was prepared easily using this structure. We then fabricated Si heterojunction solar cells using these rib wafers, and measured their implied VOC as a function of wafer thickness. The measured values were compared with device simulation results, and we found that the measured VOC agrees well with the simulated results. To optimize the rib and cell design, we also performed device simulations using various wafer thicknesses and rib dimensions.

  1. Pulsed laser deposition of silicon dioxide thin films with silicone targets for fabricating waveguide devices

    Science.gov (United States)

    Okoshi, Masayuki; Kuramatsu, Masaaki; Inoue, Narumi

    2002-06-01

    Silicon dioxide (SiO2) thin films were deposited at room temperature by 193-nm ArF excimer laser ablation of silicone in oxygen atmosphere. Only the side chains of the target were photo-dissociated during ablation to deposit Si-O bonds on a substrate in high laser fluence at about 10 J/cm2. Oxygen gas worked to oxidize the Si-O bonds ejected from the target to from SiO2 thin films at the gas pressure of 4.4 X 10-2 Torr, in addition to reducing the isolated carbon mixed into the films. We also found that the deposited rate could control refractive index of the films. The refractive index of the film deposited at 0.05 nm/pulse is greater than that of the film at 0.1 nm/pulse. Thus, a 0.2-micrometers thick SiO2 cladding film deposited at 0.1 nm/pulse was firstly formed on the whole surface of a 100- micrometers -thick polyester film, and then a 0.6 micrometers -thick SiO2 core film at 0.05 nm/pulse was fabricated in a line on the sample. The sample functioned as a waveguide device for a 633-nm line of He-Ne laser.

  2. Non-negligible Contributions to Thermal Conductivity From Localized Modes in Amorphous Silicon Dioxide

    Science.gov (United States)

    Lv, Wei; Henry, Asegun

    2016-10-01

    Thermal conductivity is important for almost all applications involving heat transfer. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate their thermal conductivity from first principles using expressions based on the phonon gas model (PGM). However, modeling of amorphous materials still has many open questions, because the PGM itself becomes questionable when one cannot rigorously define the phonon velocities. In this report, we used our recently developed Green-Kubo modal analysis (GKMA) method to study amorphous silicon dioxide (a-SiO2). The predicted thermal conductivities exhibit excellent agreement with experiments and anharmonic effects are included in the thermal conductivity calculation for all the modes in a-SiO2 for the first time. Previously, localized modes (locons) have been thought to have a negligible contribution to thermal conductivity, due to their highly localized nature. However, in a-SiO2 our results indicate that locons contribute more than 10% to the total thermal conductivity from 400 K to 800 K and they are largely responsible for the increase in thermal conductivity of a-SiO2 above room temperature. This is an effect that cannot be explained by previous methods and therefore offers new insight into the nature of phonon transport in amorphous/glassy materials.

  3. Suppression of ion-implantation induced porosity in germanium by a silicon dioxide capping layer

    Science.gov (United States)

    Tran, Tuan T.; Alkhaldi, Huda S.; Gandhi, Hemi H.; Pastor, David; Huston, Larissa Q.; Wong-Leung, Jennifer; Aziz, Michael J.; Williams, J. S.

    2016-08-01

    Ion implantation with high ion fluences is indispensable for successful use of germanium (Ge) in the next generation of electronic and photonic devices. However, Ge readily becomes porous after a moderate fluence implant ( ˜1 ×1015 ion cm-2 ) at room temperature, and for heavy ion species such as tin (Sn), holding the target at liquid nitrogen (LN2) temperature suppresses porosity formation only up to a fluence of 2 ×1016 ion cm-2 . We show, using stylus profilometry and electron microscopy, that a nanometer scale capping layer of silicon dioxide significantly suppresses the development of the porous structure in Ge during a S n - implant at a fluence of 4.5 ×1016 ion cm-2 at LN2 temperature. The significant loss of the implanted species through sputtering is also suppressed. The effectiveness of the capping layer in preventing porosity, as well as suppressing sputter removal of Ge, permits the attainment of an implanted Sn concentration in Ge of ˜15 at.% , which is about 2.5 times the maximum value previously attained. The crystallinity of the Ge-Sn layer following pulsed-laser-melting induced solidification is also greatly improved compared with that of uncapped material, thus opening up potential applications of the Ge-Sn alloy as a direct bandgap material fabricated by an ion beam synthesis technique.

  4. Non-negligible Contributions to Thermal Conductivity From Localized Modes in Amorphous Silicon Dioxide.

    Science.gov (United States)

    Lv, Wei; Henry, Asegun

    2016-10-21

    Thermal conductivity is important for almost all applications involving heat transfer. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate their thermal conductivity from first principles using expressions based on the phonon gas model (PGM). However, modeling of amorphous materials still has many open questions, because the PGM itself becomes questionable when one cannot rigorously define the phonon velocities. In this report, we used our recently developed Green-Kubo modal analysis (GKMA) method to study amorphous silicon dioxide (a-SiO2). The predicted thermal conductivities exhibit excellent agreement with experiments and anharmonic effects are included in the thermal conductivity calculation for all the modes in a-SiO2 for the first time. Previously, localized modes (locons) have been thought to have a negligible contribution to thermal conductivity, due to their highly localized nature. However, in a-SiO2 our results indicate that locons contribute more than 10% to the total thermal conductivity from 400 K to 800 K and they are largely responsible for the increase in thermal conductivity of a-SiO2 above room temperature. This is an effect that cannot be explained by previous methods and therefore offers new insight into the nature of phonon transport in amorphous/glassy materials.

  5. Biplot Analysis of Silicon Dioxide on Early Growth of Sunflower

    Directory of Open Access Journals (Sweden)

    Sabaghnia Naser

    2016-06-01

    Full Text Available Research into nanotechnology has advanced in almost all fields of technology and the aim of this study was to evaluate the role of nano-silicon dioxide (nano-SiO2 in germination performance sunflower. Germination and seedling growth are the most important stage of plant development and are critical factors to crop production and are essential to achieve optimum performance. The effects of pre-germination hydration in solutions of nano-SiO2 (0, 0.2, 0.4, 0.6, 0.8, 1 and 1.2 mM for 8 h on germination characteristics of sunflower were investigated. The trait by treatment (TT biplot explained 93% of the total variation of the standardized data (77% and 16% for the first and second principal components, respectively. According to polygon-view of TT biplot, T2 (0.2 mM had the highest values for all of the measured traits except mean germination time and the time to 50% germination. The germination percentage was determined as the best trait and showed the high association with promptness index, energy of germination and germination rate traits. The results of the present study indicated that pre-sowing seed treatments with low concentration of nano-SiO2 had favorable effect sunflower seed germination and seedling early growth. Such a similar outcome could be applied in the future to outline other crops in response to nano-particles as well as to help define tolerance tools for recommendations in stressful conditions in the world.

  6. The energy payback time of advanced crystalline silicon PV modules in 2020. A prospective study

    Energy Technology Data Exchange (ETDEWEB)

    Mann, S.A. [FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands); Van Sark, W.G.J.H.M. [Copernicus Institute, Utrecht University, CD, Utrecht (Netherlands); De Wild-Scholten, M.J. [SmartGreenScans, GH, Groet (Netherlands); Fthenakis, V.M. [Center for Life Cycle Analysis, Columbia University, New York, NY (United States); Sinke, W.C. [ECN Solar Energy, Petten (Netherlands)

    2013-02-11

    The photovoltaic (PV) market is experiencing vigorous growth, whereas prices are dropping rapidly. This growth has in large part been possible through public support, deserved for its promise to produce electricity at a low cost to the environment. It is therefore important to monitor and minimize environmental impacts associated with PV technologies. In this work, we forecast the environmental performance of crystalline silicon technologies in 2020, the year in which electricity from PV is anticipated to be competitive with wholesale electricity costs all across Europe. Our forecasts are based on technological scenario development and a prospective life cycle assessment with a thorough uncertainty and sensitivity analysis. We estimate that the energy payback time at an in-plane irradiation of 1700 kWh/(m2 year) of crystalline silicon modules can be reduced to below 0.5 years by 2020, which is less than half of the current energy payback time.

  7. 17th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, B. L.

    2007-08-01

    The National Center for Photovoltaics sponsored the 17th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, held in Vail, CO, August 5-8, 2007. This meeting provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The theme of this year's meeting was 'Expanding Technology for a Future Powered by Si Photovoltaics.'

  8. Microdefects and self-interstitial diffusion in crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Knowlton, W.B.

    1998-05-01

    In this thesis, a study is presented of D-defects and self-interstitial diffusion in silicon using Li ion (Li{sup +}) drifting in an electric field and transmission electron microscopy (TEM). Obstruction of Li{sup +} drifting has been found in wafers from certain but not all FZ p-type Si. Incomplete Li{sup +} drifting always occurs in the central region of the wafers. This work established that interstitial oxygen is not responsible for hindering Li{sup +} drifting. TEM was performed on a samples from the partially Li{sup +} drifted area and compared to regions without D-defects. Precipitates were found only in the region containing D-defects that had partially Li{sup +} drifted. This result indicates D-defects are responsible for the precipitation that halts the Li{sup +} drift process. Nitrogen (N) doping has been shown to eliminate D-defects as measured by conventional techniques. Li{sup +} drifting and D-defects provide a useful means to study Si self-interstitial diffusion. The process modeling program SUPREM-IV was used to simulate the results of Si self-interstitial diffusion obtained from Li{sup +} drifting experiments. Anomalous results from the Si self-interstitial diffusion experiments forced a re-examination of the possibility of thermal dissociation of D-defects. Thermal annealing experiments that were performed support this possibility. A review of the current literature illustrates the need for more research on the effects of thermal processing on FZ Si to understand the dissolution kinetics of D-defects.

  9. The fabrication of quantum wires in silicon utilising the characteristics of solid phase epitaxial regrowth of crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Liu, A.C.Y.; McCallum, J.C. [Melbourne Univ. Parkville, VIC (Australia). School of Physics, Microanalytical Research Centre

    1998-06-01

    The process of solid phase epitaxy (SPE) in semiconductor materials is one which has been intensively researched due to possible applications in the semiconductor industry. SPE is a solid phase transformation, in which an amorphous layer can be recrystallized either through heating or a combination of heating and ion bombardment. The transformation is believed to occur exclusively at the interface between the amorphous and crystalline layers, with individual atoms from the amorphous phase being incorporated into the crystalline phase by some point defect mechanism. The process has been observed to follow an Arrhenius temperature dependence. A wafer silicon was subjected to a multi-energy silicon implant through a fine nickel grid to amorphise region to a depth of 5{mu}m creating an array of amorphous wells. Metal impurity atoms were then implanted in this region at energy of 500 keV. Samples were examined using an optical microscope and the Alphastep profiler at RMIT. It was confirmed that burgeoning wells were about 2 {mu}m wide and rose about 0.01 {mu}m above the silicon substrate. Extended abstract. 4 refs., 3 figs.

  10. In-Situ Characterization of Potential-Induced Degradation in Crystalline Silicon Photovoltaic Modules Through Dark I–V Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Wei; Hacke, Peter; Singh, Jai Prakash; Chai, Jing; Wang, Yan; Ramakrishna, Seeram; Aberle, Armin G.; Khoo, Yong Sheng

    2017-01-01

    A temperature correction methodology for in-situ dark I-V(DIV) characterization of conventional p-type crystalline silicon photovoltaic (PV) modules undergoing potential-induced degradation (PID) is proposed.

  11. Selective functionalization and loading of biomolecules in crystalline silicon nanotube field-effect-transistors.

    Science.gov (United States)

    Kwon, Soonshin; Chen, Zack C Y; Noh, Hyunwoo; Lee, Ju Hun; Liu, Hang; Cha, Jennifer N; Xiang, Jie

    2014-07-21

    Crystalline silicon nanotubes (Si NTs) provide distinctive advantages as electrical and biochemical analysis scaffolds through their unique morphology and electrical tunability compared to solid nanowires or amorphous/non-conductive nanotubes. Such potential is investigated in this report. Gate-dependent four-probe current-voltage analysis reveals electrical properties such as resistivity to differ by nearly 3 orders of magnitude between crystalline and amorphous Si NTs. Analysis of transistor transfer characteristics yields a field effect mobility of 40.0 cm(2) V(-1) s(-1) in crystalline Si NTs. The hollow morphology also allows selective inner/outer surface functionalization and loading capability either as a carrier for molecular targets or as a nanofluidic channel for biomolecular assays. We present for the first time a demonstration of internalization of fluorescent dyes (rhodamine) and biomolecules (BSA) in Si NTs as long as 22 μm in length.

  12. Microdefects and self-interstitial diffusion in crystalline silicon

    Science.gov (United States)

    Knowlton, William Barthelemy

    In this thesis, a study is presented of D-defects and self-interstitial diffusion in silicon using Li ion (Lisp+) drifting in an electric field and transmission electron microscopy (TEM). Obstruction of Lisp+ drifting has been found in wafers from certain but not all FZ p-type Si. Incomplete Lisp+ drifting always occurs in the central region of the wafers. This work established that interstitial oxygen is not responsible for hindering Lisp+ drifting. The Osb i concentration was measured ({˜}2× 10sp{15}\\ cmsp{-3}) by local vibrational mode Fourier transform infrared spectroscopy and did not vary radially across the wafer. TEM was performed on a samples from the partially Lisp+ drifted area and compared to regions without D-defects. Precipitates were found only in the region containing D-defects that had partially Lisp+ drifted. This result indicates D-defects are responsible for the precipitation that halts the Lisp+ drift process. The precipitates were characterized using selected area diffraction (SAD) and image contrast analysis. The results suggested that the precipitates may cause stacking faults and their identity may be lithium silicides such as Lisb{21}Sisb5\\ and\\ Lisb{13}Sisb4. TEM revealed a decreasing distribution of Li precipitates as a function of Lisp+ drift depth along the growth direction. A preliminary model is presented that simulates Lisp+ drifting. The objective of the model is to incorporate the Li precipitate density distribution and Lisp+ drift depth to extract the size and capture cross-section of the D-defects. Nitrogen (N) doping has been shown to eliminate D-defects as measured by conventional techniques. However, Lisp+ drifting has shown that D-defects are indeed still present. Lisp+ drifting is able to detect D-defects at concentrations lower than conventional techniques. Lisp+ drifting and D-defects provide a useful means to study Si self-interstitial diffusion. The process modeling program SUPREM-IV was used to simulate the

  13. Raman Spectra of High-κ Dielectric Layers Investigated with Micro-Raman Spectroscopy Comparison with Silicon Dioxide

    Directory of Open Access Journals (Sweden)

    P. Borowicz

    2013-01-01

    Full Text Available Three samples with dielectric layers from high-κ dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high-κ dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the structure of this material. Raman spectra recorded for as-deposited hafnium oxide are similar to the results obtained for silicon dioxide layer. After thermal treatment especially at higher temperatures (600°C and above, the structure of hafnium oxide becomes similar to the bulk non-densified silicon dioxide.

  14. Simple processing of back-contacted silicon heterojunction solar cells using selective-area crystalline growth

    Science.gov (United States)

    Tomasi, Andrea; Paviet-Salomon, Bertrand; Jeangros, Quentin; Haschke, Jan; Christmann, Gabriel; Barraud, Loris; Descoeudres, Antoine; Seif, Johannes Peter; Nicolay, Sylvain; Despeisse, Matthieu; de Wolf, Stefaan; Ballif, Christophe

    2017-04-01

    For crystalline-silicon solar cells, voltages close to the theoretical limit are nowadays readily achievable when using passivating contacts. Conversely, maximal current generation requires the integration of the electron and hole contacts at the back of the solar cell to liberate its front from any shadowing loss. Recently, the world-record efficiency for crystalline-silicon single-junction solar cells was achieved by merging these two approaches in a single device; however, the complexity of fabricating this class of devices raises concerns about their commercial potential. Here we show a contacting method that substantially simplifies the architecture and fabrication of back-contacted silicon solar cells. We exploit the surface-dependent growth of silicon thin films, deposited by plasma processes, to eliminate the patterning of one of the doped carrier-collecting layers. Then, using only one alignment step for electrode definition, we fabricate a proof-of-concept 9-cm2 tunnel-interdigitated back-contact solar cell with a certified conversion efficiency >22.5%.

  15. Simple processing of back-contacted silicon heterojunction solar cells using selective-area crystalline growth

    KAUST Repository

    Tomasi, Andrea

    2017-04-24

    For crystalline-silicon solar cells, voltages close to the theoretical limit are nowadays readily achievable when using passivating contacts. Conversely, maximal current generation requires the integration of the electron and hole contacts at the back of the solar cell to liberate its front from any shadowing loss. Recently, the world-record efficiency for crystalline-silicon single-junction solar cells was achieved by merging these two approaches in a single device; however, the complexity of fabricating this class of devices raises concerns about their commercial potential. Here we show a contacting method that substantially simplifies the architecture and fabrication of back-contacted silicon solar cells. We exploit the surface-dependent growth of silicon thin films, deposited by plasma processes, to eliminate the patterning of one of the doped carrier-collecting layers. Then, using only one alignment step for electrode definition, we fabricate a proof-of-concept 9-cm2 tunnel-interdigitated back-contact solar cell with a certified conversion efficiency >22.5%.

  16. Nanopatterning of Crystalline Silicon Using Anodized Aluminum Oxide Templates for Photovoltaics

    Science.gov (United States)

    Chao, Tsu-An

    A novel thin film anodized aluminum oxide templating process was developed and applied to make nanopatterns on crystalline silicon to enhance the optical properties of silicon. The thin film anodized aluminum oxide was created to improve the conventional thick aluminum templating method with the aim for potential large scale fabrication. A unique two-step anodizing method was introduced to create high quality nanopatterns and it was demonstrated that this process is superior over the original one-step approach. Optical characterization of the nanopatterned silicon showed up to 10% reduction in reflection in the short wavelength range. Scanning electron microscopy was also used to analyze the nanopatterned surface structure and it was found that interpore spacing and pore density can be tuned by changing the anodizing potential.

  17. Application of nano-crystalline silicon film in the fabrication of field-emission pressure sensor

    Institute of Scientific and Technical Information of China (English)

    廖波; 陈旻; 孔德文; 张大成; 李婷

    2003-01-01

    A kind of filed-emission array pressure sensor is designed based on the quantum tunnel effect. The nano-crystalline silicon film is prepared by chemical vapor deposition (CVD) method, with the grain dimension and thickness of the film 3-9 nm and 30-40 nm, respectively. The nano-crystal- line silicon film is introduced into the cathode cones of the sensor, functioning as the essential emission part. The silicon nano phase is analyzed by HREM and TED, the microstructure of the single emitter and emitters array is inspected by SEM, and the field emission characteristics of the device are studied by an HP4145B transistor tester. The experimental results show that the measured current density emitted from the effective area of the sensor can reach 53.5 A/m2 when the exterior electric field is 5.6×105 V/m.

  18. Drift mechanism of mass transfer on heterogeneous reaction in crystalline silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kukushkin, S.A. [Institute of Problems of Mechanical Engineering, Russian Academy of Science, St Petersburg, 199178 (Russian Federation); St. Petersburg National Research University of Information Technologies, Mechanics and Optics, 197101 (Russian Federation); Osipov, A.V., E-mail: Andrey.V.Osipov@gmail.com [Institute of Problems of Mechanical Engineering, Russian Academy of Science, St Petersburg, 199178 (Russian Federation); St. Petersburg National Research University of Information Technologies, Mechanics and Optics, 197101 (Russian Federation)

    2017-05-01

    This work aims to study the pressure dependence of the thickness of the epitaxial silicon carbide film growing from crystalline silicon due to the heterogeneous reaction with gaseous carbon monoxide. It turned out that this dependence exhibits the clear maximum. On further pressure increasing the film thickness decreases. The theoretical model has been developed which explains such a character of the dependence by the fact that the gaseous silicon monoxide reaction product inhibits the drift of the gaseous reagent through the channels of a crystal lattice, thus decreasing their hydraulic diameter. In the proposed hydraulic model, the dependences of the film thickness both on the gas pressure and time have been calculated. It was shown that not only the qualitative but also quantitative correspondence between theoretical and experimental results takes place. As one would expect, due to the Einstein relation, at short growth times the drift model coincides with the diffusion one. Consequences of this drift mechanism of epitaxial film growing are discussed. - Graphical abstract: This work aims to study the pressure dependence of the thickness of the epitaxial silicon carbide film growing from crystalline silicon due to the heterogeneous reaction with gaseous carbon monoxide. It turned out that this dependence exhibits the clear maximum. On further pressure increasing the film thickness decreases. The theoretical model has been developed which explains such a character of the dependence by the fact that the gaseous silicon monoxide reaction product inhibits the drift of the gaseous reagent through the channels of a crystal lattice, thus decreasing their hydraulic diameter. - Highlights: • It is established that the greater pressure, the smaller is the reaction rate. • The reaction product prevents penetration of the reagent into a reaction zone. • For description the hydraulic model of crystal lattice channels is developed. • Theoretical results for polytropic

  19. Substrate bias effect on crystallinity of polycrystalline silicon thin films prepared by pulsed ion-beam evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Fazlat; Gunji, Michiharu; Yang, Sung-Chae; Suzuki, Tsuneo; Suematsu, Hisayuki; Jiang, Weihua; Yatsui, Kiyoshi [Nagaoka Univ. of Technology, Extreme Energy-Density Research Inst., Nagaoka, Niigata (Japan)

    2002-06-01

    The deposition of polycrystalline silicon thin films has been tried by a pulsed ion-beam evaporation method, where high crystallinity and deposition rate have been achieved without heating the substrate. The crystallinity and the deposition rate were improved by applying bias voltage to the substrate, where instantaneous substrate heating might have occurred by ion-bombardment. (author)

  20. Biocompatibility of cerium dioxide and silicon dioxide nanoparticles with endothelial cells

    Directory of Open Access Journals (Sweden)

    Claudia Strobel

    2014-10-01

    Full Text Available Cerium dioxide (CeO2 and silicon dioxide (SiO2 nanoparticles are of widespread use in modern life. This means that human beings are markedly exposed to them in their everyday life. Once passing biological barriers, these nanoparticles are expected to interact with endothelial cells, leading to systemic alterations with distinct influences on human health. In the present study we observed the metabolic impact of differently sized CeO2 (8 nm; 35 nm and SiO2 nanoparticles (117 nm; 315 nm on immortalized human microvascular (HMEC-1 and primary macrovascular endothelial cells (HUVEC, with particular focus on the CeO2 nanoparticles. The characterization of the CeO2 nanoparticles in cell culture media with varying serum content indicated a steric stabilization of nanoparticles due to interaction with proteins. After cellular uptake, the CeO2 nanoparticles were localized around the nucleus in a ring-shaped manner. The nanoparticles revealed concentration and time, but no size-dependent effects on the cellular adenosine triphosphate levels. HUVEC reacted more sensitively to CeO2 nanoparticle exposure than HMEC-1. This effect was also observed in relation to cytokine release after nanoparticle treatment. The CeO2 nanoparticles exhibited a specific impact on the release of diverse proteins. Namely, a slight trend towards pro-inflammatory effects, a slight pro-thrombotic impact, and an increase of reactive oxygen species after nanoparticle exposure were observed with increasing incubation time. For SiO2 nanoparticles, concentration- and time-dependent effects on the metabolic activity as well as pro-inflammatory reactions were detectable. In general, the effects of the investigated nanoparticles on endothelial cells were rather insignificant, since the alterations on the metabolic cell activity became visible at a nanoparticle concentration that is by far higher than those expected to occur in the in vivo situation (CeO2 nanoparticles: 100 µg/mL; SiO2

  1. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Prathap Pathi

    2017-01-01

    Full Text Available Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm and is slightly lower (by ~5% at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm silicon and just 1%–2% for thicker (>100 μm cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  2. Growth and etch rate study of low temperature anodic silicon dioxide thin films.

    Science.gov (United States)

    Ashok, Akarapu; Pal, Prem

    2014-01-01

    Silicon dioxide (SiO2) thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs) and microelectromechanical systems (MEMS). Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics.

  3. Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

    Directory of Open Access Journals (Sweden)

    Akarapu Ashok

    2014-01-01

    Full Text Available Silicon dioxide (SiO2 thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs and microelectromechanical systems (MEMS. Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics.

  4. Programmable SERS active substrates for chemical and biosensing applications using amorphous/crystalline hybrid silicon nanomaterial

    Science.gov (United States)

    Powell, Jeffery Alexander; Venkatakrishnan, Krishnan; Tan, Bo

    2016-01-01

    We present the creation of a unique nanostructured amorphous/crystalline hybrid silicon material that exhibits surface enhanced Raman scattering (SERS) activity. This nanomaterial is an interconnected network of amorphous/crystalline nanospheroids which form a nanoweb structure; to our knowledge this material has not been previously observed nor has it been applied for use as a SERS sensing material. This material is formed using a femtosecond synthesis technique which facilitates a laser plume ion condensation formation mechanism. By fine-tuning the laser plume temperature and ion interaction mechanisms within the plume, we are able to precisely program the relative proportion of crystalline Si to amorphous Si content in the nanospheroids as well as the size distribution of individual nanospheroids and the size of Raman hotspot nanogaps. With the use of Rhodamine 6G (R6G) and Crystal Violet (CV) chemical dyes, we have been able to observe a maximum enhancement factor of 5.38 × 106 and 3.72 × 106 respectively, for the hybrid nanomaterial compared to a bulk Si wafer substrate. With the creation of a silicon-based nanomaterial capable of SERS detection of analytes, this work demonstrates a redefinition of the role of nanostructured Si from an inactive to SERS active role in nano-Raman sensing applications.

  5. Band offsets at the crystalline / hydrogenated amorphous silicon interface from first-principles

    Science.gov (United States)

    Hazrati, Ebrahim; Jarolimek, Karol; de Wijs, Gilles A.; InstituteMolecules; Materials Team

    2015-03-01

    The heterojunction formed between crystalline silicon (c-Si) and hydrogenated amorphous silicon (a-Si:H) is a key component of a new type of high-efficiency silicon solar cell. Since a-Si:H has a larger band gap than c-Si, band offsets are formed at the interface. A band offset at the minority carrier band will mitigate recombination and lead to an increased efficiency. Experimental values of band offsets scatter in a broad range. However, a recent meta-analysis of the results (W. van Sark et al.pp. 405, Springer 2012) gives a larger valence offset (0.40 eV) than the conduction offset (0.15 eV). In light of the conflicting reports our goal is to calculate the band offsets at the c-Si/a-Si:H interface from first-principles. We have prepared several atomistic models of the interface. The crystalline part is terminated with (111) surfaces on both sides. The amorphous structure is generated by simulating an annealing process at 1100 K, with DFT molecular dynamics. Once the atomistic is ready it can be used to calculate the electronic structure of the interface. Our preliminary results show that the valence offset is larger than the conduction band offset.

  6. Evolutionary process development towards next generation crystalline silicon solar cells : a semiconductor process toolbox application

    Science.gov (United States)

    John, J.; Prajapati, V.; Vermang, B.; Lorenz, A.; Allebe, C.; Rothschild, A.; Tous, L.; Uruena, A.; Baert, K.; Poortmans, J.

    2012-08-01

    Bulk crystalline Silicon solar cells are covering more than 85% of the world's roof top module installation in 2010. With a growth rate of over 30% in the last 10 years this technology remains the working horse of solar cell industry. The full Aluminum back-side field (Al BSF) technology has been developed in the 90's and provides a production learning curve on module price of constant 20% in average. The main reason for the decrease of module prices with increasing production capacity is due to the effect of up scaling industrial production. For further decreasing of the price per wattpeak silicon consumption has to be reduced and efficiency has to be improved. In this paper we describe a successive efficiency improving process development starting from the existing full Al BSF cell concept. We propose an evolutionary development includes all parts of the solar cell process: optical enhancement (texturing, polishing, anti-reflection coating), junction formation and contacting. Novel processes are benchmarked on industrial like baseline flows using high-efficiency cell concepts like i-PERC (Passivated Emitter and Rear Cell). While the full Al BSF crystalline silicon solar cell technology provides efficiencies of up to 18% (on cz-Si) in production, we are achieving up to 19.4% conversion efficiency for industrial fabricated, large area solar cells with copper based front side metallization and local Al BSF applying the semiconductor toolbox.

  7. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    Science.gov (United States)

    Ghoneim, Mohamed T.; Fahad, Hossain M.; Hussain, Aftab M.; Rojas, Jhonathan P.; Torres Sevilla, Galo A.; Alfaraj, Nasir; Lizardo, Ernesto B.; Hussain, Muhammad M.

    2015-12-01

    In today's digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical "through silicon" micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  8. Impact of microcrystalline silicon carbide growth using hot-wire chemical vapor deposition on crystalline silicon surface passivation

    Energy Technology Data Exchange (ETDEWEB)

    Pomaska, M., E-mail: m.pomaksa@fz-juelich.de [Forschungszentrum Jülich, IEK5-Photovoltaics, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); Beyer, W. [Helmholtz-Zentrum Berlin für Materialien und Energie, Silicon Photovoltaics, Kekuléstrasse 5, 12489 Berlin (Germany); Neumann, E. [Forschungszentrum Jülich, PGI-8-PT, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); Finger, F.; Ding, K. [Forschungszentrum Jülich, IEK5-Photovoltaics, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany)

    2015-11-30

    Highly crystalline microcrystalline silicon carbide (μc-SiC:H) with excellent optoelectronic material properties is a promising candidate as highly transparent doped layer in silicon heterojunction (SHJ) solar cells. These high quality materials are usually produced using hot wire chemical vapor deposition under aggressive growth conditions giving rise to the removal of the underlying passivation layer and thus the deterioration of the crystalline silicon (c-Si) surface passivation. In this work, we introduced the n-type μc-SiC:H/n-type μc-SiO{sub x}:H/intrinsic a-SiO{sub x}:H stack as a front layer configuration for p-type SHJ solar cells with the μc-SiO{sub x}:H layer acting as an etch-resistant layer against the reactive deposition conditions during the μc-SiC:H growth. We observed that the unfavorable expansion of micro-voids at the c-Si interface due to the in-diffusion of hydrogen atoms through the layer stack might be responsible for the deterioration of surface passivation. Excellent lifetime values were achieved under deposition conditions which are needed to grow high quality μc-SiC:H layers for SHJ solar cells. - Highlights: • High surface passivation quality was preserved after μc-SiC:H deposition. • μc-SiC:H/μc-SiO{sub x}:H/a-SiO{sub x}:H stack a promising front layer configuration • Void expansion at a-SiO{sub x}:H/c-Si interface for deteriorated surface passivation • μc-SiC:H provides a high transparency and electrical conductivity.

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

    Science.gov (United States)

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

    2016-12-28

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

  10. The Temperature Dependence Coefficients of Amorphous Silicon and Crystalline Photovoltaic Modules Using Malaysian Field Test Investigation

    Directory of Open Access Journals (Sweden)

    Sulaiman Shaari

    2009-01-01

    Full Text Available The temperature dependence coefficients of amorphous silicon and crystalline photovoltaic (PV modules using Malaysian field data have been obtained using linear regression technique. This is achieved by studying three test stand-alone PV-battery systems using 62 Wp a-Si, 225 Wp multi-crystalline and 225 Wp mono-crystalline PV modules. These systems were designed to provide electricity for rural domestic loads at 200 W, 500 W and 530 W respectively. The systems were installed in the field with data monitored using data loggers. Upon analysis, the study found that the normalized power output per operating array temperature for the amorphous silicon modules, multi-crystalline modules and mono-crystalline modules were: +0.037 per°C, +0.0225 per °C and +0.0263 per °C respectively. In addition, at a solar irradiance value of 500 Wm-2, the current, voltage, power and efficiency dependence coefficients on operating array temperatures obtained from linear regression were: +37.0 mA per °C, -31.8 mV per °C, -0.1036 W per °C and -0.0214% per °C, for the a-Si modules, +22.5 mA per °C, -39.4 mV per °C, -0.2525 W per °C, -0.072 % per °C for the multi-crystalline modules and +26.3 mA per °C, -32.6 mV per °C, -0.1742 W per °C, -0.0523 % per °C for the mono-crystalline modules. These findings have a direct impact on all systems design and sizing in similar climate regions. It is thus recommended that the design and sizing of PV systems in the hot and humid climate regions of the globe give due address to these findings.

  11. Microcellular foaming of silicone rubber with supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Hong, In-Kwon; Lee, Sangmook [Dankook University, Youngin (Korea, Republic of)

    2014-01-15

    In spite of great concern on the industrial application of microcellular silicone rubber foams, such as in electric and medical devices, only a few works can be found about the foaming of silicone rubber. In this study, microcellular silicone rubber foams with a cell size of 12 µm were successfully prepared with curing by heat and foaming by supercritical CO{sub 2} as a green blowing agent. The microcellular silicone rubber foams exhibited a well-defined cell structure and a uniform cell size distribution. The crosslinking and foaming of silicone rubber was carried out separately. After foaming, the silicone rubber foam was cross-linked again to stabilize the foam structure and further improve its mechanical properties. Foaming process of cross-linked silicone rubber should be designed carefully based on the viscoelastic properties because of its elastic volume recovery in the atmosphere. The basic crosslinking condition for small cell size and high cell density was obtained after investigating the rheological behavior during crosslinking.

  12. Follow the track: The effects of silicon dioxide on GTA welding

    NARCIS (Netherlands)

    Schrauwers, A.

    2001-01-01

    Silicon dioxide, in other words sand, turns out to be a highly useful helper for arc welding processes. It can be used as a tracer for a welding robot to follow the weld line and it can also make welding go faster and "deeper". At the Materials Science department of the Delft University of Technolog

  13. Spatial control of direct chemical vapor deposition of graphene on silicon dioxide by directional copper dewetting

    NARCIS (Netherlands)

    van den Beld, Wesley Theodorus Eduardus; van den Berg, Albert; Eijkel, Jan C.T.

    2016-01-01

    In this paper we present a method for the spatial control of direct graphene synthesis onto silicon dioxide by controlled dewetting. The dewetting process is controlled through a combination of using a grooved substrate and conducting copper deposition at an angle. The substrate is then treated

  14. Spatial control of direct chemical vapor deposition of graphene on silicon dioxide by directional copper dewetting

    NARCIS (Netherlands)

    Beld, van den Wesley T.E.; Berg, van den Albert; Eijkel, Jan C.T.

    2016-01-01

    In this paper we present a method for the spatial control of direct graphene synthesis onto silicon dioxide by controlled dewetting. The dewetting process is controlled through a combination of using a grooved substrate and conducting copper deposition at an angle. The substrate is then treated usin

  15. Two-dimensional modeling of the back amorphous-crystalline silicon heterojunction (BACH) photovoltaic device

    Science.gov (United States)

    Chowdhury, Zahidur R.; Chutinan, Alongkarn; Gougam, Adel B.; Kherani, Nazir P.; Zukotynski, Stefan

    2010-06-01

    Back Amorphous-Crystalline Silicon Heterojunction (BACH)1 solar cell can be fabricated using low temperature processes while integrating high efficiency features of heterojunction silicon solar cells and back-contact homojunction solar cells. This article presents a two-dimensional modeling study of the BACH cell concept. A parametric study of the BACH cell has been carried out using Sentaurus after benchmarking the software. A detailed model describing the optical generation is defined. Solar cell efficiency of 24.4% is obtained for AM 1.5 global spectrum with VOC of greater than 720 mV and JSC exceeding 40 mA/cm2, considering realistic surface passivation quality and other dominant recombination processes.

  16. Design and optimization of ultrathin crystalline silicon solar cells using an efficient back reflector

    Directory of Open Access Journals (Sweden)

    S. Saravanan

    2015-05-01

    Full Text Available Thin film solar cells are cheaper but having low absorption in longer wavelength and hence, an effective light trapping mechanism is essential. In this work, we proposed an ultrathin crystalline silicon solar cell which showed extraordinary performance due to enhanced light absorption in visible and infrared part of solar spectrum. Various designing parameters such as number of distributed Bragg reflector (DBR pairs, anti-reflection layer thickness, grating thickness, active layer thickness, grating duty cycle and period were optimized for the optimal performance of solar cell. An ultrathin silicon solar cell with 40 nm active layer could produce an enhancement in cell efficiency ∼15 % and current density ∼23 mA/cm2. This design approach would be useful for the realization of new generation of solar cells with reduced active layer thickness.

  17. Temperature dependence of the radiative recombination coefficient in crystalline silicon from spectral photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Hieu T., E-mail: hieu.nguyen@anu.edu.au; Macdonald, Daniel [Research School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, ACT 0200 (Australia); Baker-Finch, Simeon C. [Research School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, ACT 0200 (Australia); PV Lighthouse, Coledale, NSW 2515 (Australia)

    2014-03-17

    The radiative recombination coefficient B(T) in crystalline silicon is determined for the temperature range 90–363 K, and in particular from 270 to 350 K with an interval of 10 K, where only sparse data are available at present. The band-band absorption coefficient established recently by Nguyen et al. [J. Appl. Phys. 115, 043710 (2014)] via photoluminescence spectrum measurements is employed to compute the values of B(T) at various temperatures. The results agree very well with literature data from Trupke et al. [J. Appl. Phys. 94, 4930 (2003).] We present a polynomial parameterization describing the temperature dependence of the product of B(T) and the square of the intrinsic carrier density. We also find that B(T) saturates at a near constant value at room temperature and above for silicon samples with relatively low free carrier densities.

  18. Incoherent-light processing of single- and poly-crystalline silicon solar cells

    Science.gov (United States)

    Nielsen, L. D.; Larsen, A. N.

    Transient heating with incoherent continuous light from a xenon arc-lamp has been studied as a possible process step in the production of single- and poly-crystalline silicon solar cells. Annealing of phosphorus and arsenic ion implantations have been made, with phosphorus implantations leading to solar cell efficiences of 8.3 and 5.8 percent for 100 single crystal and Wacker-SILSO materials, respectively, both without AR-coating. Furthermore, incoherent-light induced diffusion of phosphorus from spin-on deposited doped oxide layer has been studied and has resulted in efficiencies of 7.9 and 6.6 percent, respectively, for the same two types of material. This latter process is concluded to be a promising technique for production of low-cost silicon solar cells with efficiencies of at least 10 percent without any vacuum or high-temperature furnace process steps.

  19. Impact of temperature on performance of series and parallel connected mono-crystalline silicon solar cells

    Directory of Open Access Journals (Sweden)

    Subhash Chander

    2015-11-01

    Full Text Available This paper presents a study on impact of temperature on the performance of series and parallel connected mono-crystalline silicon (mono-Si solar cell employing solar simulator. The experiment was carried out at constant light intensity 550 W/m2with cell temperature in the range 25–60 oC for single, series and parallel connected mono-Si solar cells. The performance parameters like open circuit voltage, maximum power, fill factor and efficiency are found to decrease with cell temperature while the short circuit current is observed to increase. The experimental results reveal that silicon solar cells connected in series and parallel combinations follow the Kirchhoff’s laws and the temperature has a significant effect on the performance parameters of solar cell.

  20. Microsystems enabled photovoltaics: 14.9% efficient 14 {mu}m thick crystalline silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Campa, Jose L. [Sandia National Laboratories, M.S. 1080, 1515 Eubank Blvd. SE, Albuquerque, NM 87123 (United States); University of Texas at El Paso, Department of Electrical and Computer Engineering, 500 West University Avenue, El Paso, TX 79968 (United States); Okandan, Murat; Resnick, Paul J.; Clews, Peggy; Pluym, Tammy; Grubbs, Robert K.; Gupta, Vipin P.; Nielson, Gregory N. [Sandia National Laboratories, M.S. 1080, 1515 Eubank Blvd. SE, Albuquerque, NM 87123 (United States); Zubia, David [University of Texas at El Paso, Department of Electrical and Computer Engineering, 500 West University Avenue, El Paso, TX 79968 (United States)

    2011-02-15

    Crystalline silicon solar cells 10-15 times thinner than traditional commercial c-Si cells with 14.9% efficiency are presented with modeling, fabrication, and testing details. These cells are 14 {mu}m thick, 250 {mu}m wide, and have achieved 14.9% solar conversion efficiency under AM 1.5 spectrum. First, modeling results illustrate the importance of high-quality passivation to achieve high efficiency in thin silicon, back contacted solar cells. Then, the methodology used to fabricate these ultra thin devices by means of established microsystems processing technologies is presented. Finally, the optimization procedure to achieve high efficiency as well as the results of the experiments carried out with alumina and nitride layers as passivation coatings are discussed. (author)

  1. Dissolution chemistry and biocompatibility of single-crystalline silicon nanomembranes and associated materials for transient electronics.

    Science.gov (United States)

    Hwang, Suk-Won; Park, Gayoung; Edwards, Chris; Corbin, Elise A; Kang, Seung-Kyun; Cheng, Huanyu; Song, Jun-Kyul; Kim, Jae-Hwan; Yu, Sooyoun; Ng, Joanne; Lee, Jung Eun; Kim, Jiyoung; Yee, Cassian; Bhaduri, Basanta; Su, Yewang; Omennetto, Fiorenzo G; Huang, Yonggang; Bashir, Rashid; Goddard, Lynford; Popescu, Gabriel; Lee, Kyung-Mi; Rogers, John A

    2014-06-24

    Single-crystalline silicon nanomembranes (Si NMs) represent a critically important class of material for high-performance forms of electronics that are capable of complete, controlled dissolution when immersed in water and/or biofluids, sometimes referred to as a type of "transient" electronics. The results reported here include the kinetics of hydrolysis of Si NMs in biofluids and various aqueous solutions through a range of relevant pH values, ionic concentrations and temperatures, and dependence on dopant types and concentrations. In vitro and in vivo investigations of Si NMs and other transient electronic materials demonstrate biocompatibility and bioresorption, thereby suggesting potential for envisioned applications in active, biodegradable electronic implants.

  2. The radiation damage of crystalline silicon PN diode in tritium beta-voltaic battery.

    Science.gov (United States)

    Lei, Yisong; Yang, Yuqing; Liu, Yebing; Li, Hao; Wang, Guanquan; Hu, Rui; Xiong, Xiaoling; Luo, Shunzhong

    2014-08-01

    A tritium beta-voltaic battery using a crystalline silicon convertor composed of (100)Si/SiO2/Si3N4 film degrades remarkably with radiation from a high intensity titanium tritide film. Simulation and experiments were carried out to investigate the main factor causing the degradation. The radiation damages mainly comes from the x-ray emitted from the titanium tritide film and beta particle can relieve the damages. The x-ray radiation induced positive charges in the SiO2 film destroying the output property of the PN diode with the induction of an electric field.

  3. Dry technologies for the production of crystalline silicon solar cells; Trockentechnologien zur Herstellung von kristallinen Siliziumsolarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Rentsch, J.

    2005-04-15

    Within this work, dynamic plasma etching technologies for the industrial production of crystalline silicon solar cells has been investigated. The research activity can be separated into three major steps: the characterisation of the etching behaviour of a newly developed dynamic plasma etching system, the development and analysis of dry etching processes for solar cell production and the determination of the ecological and economical impacts of such a new technology compared to standard up to date technologies. The characterisation of the etching behaviour has been carried out for two different etching sources, a low frequency (110 kHz) and a microwave (2.45 GHz) plasma source. The parameter of interest was the delivered ion energy of each source mainly determining the reachable etch rate. The etch rate turned out to be the main most critical parameter concerning the reachable wafer throughput per hour. Other points of interest in characterisation of the etching system were the material of the transport carriers, the silicon load as well as the process temperatures. The development of different dry etching processes targets the design of a complete dry production process for crystalline silicon solar cells. Therefore etching processes for saw damage removal, texturing, edge isolation as well as etching of dielectric layers have been developed and optimised. The major benefits of a complete dry production process would be the reduction of handling steps in between process steps and therefore offers a large cost reduction potential. For multicrystalline silicon solar cells a cost reduction potential of 5 % compared to a standard wet chemical based reference process could be realized only including the dry etching of a phosphorus silicate glass layer after diffusion. Further reduction potential offers the implementation of a dry texturing process due to a significant efficiency increase. (orig.)

  4. Recycling WEEE: Extraction and concentration of silver from waste crystalline silicon photovoltaic modules.

    Science.gov (United States)

    Dias, Pablo; Javimczik, Selene; Benevit, Mariana; Veit, Hugo; Bernardes, Andréa Moura

    2016-11-01

    Photovoltaic modules (or panels) are important power generators with limited lifespans. The modules contain known pollutants and valuable materials such as silicon, silver, copper, aluminum and glass. Thus, recycling such waste is of great importance. To date, there have been few published studies on recycling silver from silicon photovoltaic panels, even though silicon technology represents the majority of the photovoltaic market. In this study, the extraction of silver from waste modules is justified and evaluated. It is shown that the silver content in crystalline silicon photovoltaic modules reaches 600g/t. Moreover, two methods to concentrate silver from waste modules were studied, and the use of pyrolysis was evaluated. In the first method, the modules were milled, sieved and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 94%. In the second method, photovoltaic modules were milled, sieved, subjected to pyrolysis at 500°C and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 92%. The first method is preferred as it consumes less energy and presents a higher yield of silver. This study shows that the use of pyrolysis does not assist in the extraction of silver, as the yield was similar for both methods with and without pyrolysis.

  5. Preservation of Seed Crystals in Feedstock Melting for Cast Quasi-Single Crystalline Silicon Ingots

    Directory of Open Access Journals (Sweden)

    Zaoyang Li

    2013-01-01

    Full Text Available The preservation of seed crystals is important for the casting of quasi-single crystalline (QSC silicon ingots. We carried out transient global simulations of the feedstock melting process in an industrial-sized directional solidification (DS furnace to investigate key factors influencing seed preservation. The power distribution between the top and side heaters is adjusted in the conventional furnace for multicrystalline silicon ingots and in the evolved furnace with a partition block for QSC silicon ingots. The evolution of the solid-liquid interface for melting and the temperature distribution in the furnace core area are analyzed. The power distribution can influence the temperature gradient in the silicon domain significantly. However, its effect on seed preservation is limited in both furnaces. Seed crystals can be preserved in the evolved furnace, as the partition block reduces the radiant heat flux from the insulation walls to the heat exchange block and prevents the heat flowing upwards under the crucible. Therefore, the key to seed preservation is to control radiant heat transfer in the DS furnace and guarantee downward heat flux under the crucible.

  6. Optical properties and surface damage studies of crystalline silicon caused by swift iron ions

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, S.K., E-mail: skdubey@physics.mu.ac.in

    2016-05-15

    p-Type silicon samples irradiated with 70 MeV {sup 56}Fe{sup 5+} ions for various fluences varying between 5 × 10{sup 12} and 4 × 10{sup 14} ions cm{sup −2} have been studied using spectroscopic ellipsometry and Fourier transform infrared spectroscopy. The microstructure of the irradiated samples was modeled from ellipsometric data, using a multilayer optical model and Bruggeman effective medium approximation. The values of pseudodielectric function, absorption coefficient and Penn gap energy were determined with respect to ion fluence. The effective medium analysis suggests that the superficial silicon layer can be explained as a mixture of crystalline and damaged silicon. The thickness of the damaged layer and percentage of voids present in the layer were found to increase with increase in the ion fluence. The effect of disorder on the interband optical spectra, especially on the critical point E{sub 1} at 3.4 eV was found to vary with ion fluence. A red shift in the critical point E{sub 1} with increasing ion fluence was observed. FTIR study showed of silicon samples irradiated with 70 MeV {sup 56}Fe{sup 5+} ions produced the oscillations in the spectral region 1000–400 cm{sup −1}. As irradiated sample showed more pronounced fringes, while contrast of the fringes and amplitude both were found to decrease with increase in depth.

  7. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Science.gov (United States)

    Pathi, Prathap; Peer, Akshit; Biswas, Rana

    2017-01-01

    Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping. PMID:28336851

  8. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells.

    Science.gov (United States)

    Pathi, Prathap; Peer, Akshit; Biswas, Rana

    2017-01-13

    Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm² photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  9. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-12-11

    In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  10. Thermal conductivity reduction of crystalline silicon by high-pressure torsion.

    Science.gov (United States)

    Harish, Sivasankaran; Tabara, Mitsuru; Ikoma, Yoshifumi; Horita, Zenji; Takata, Yasuyuki; Cahill, David G; Kohno, Masamichi

    2014-01-01

    We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk crystalline silicon when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity of the HPT-processed samples were measured using picosecond time domain thermoreflectance. Thermal conductivity measurements show that the HPT-processed samples have a lattice thermal conductivity reduction by a factor of approximately 20 (from intrinsic single crystalline value of 142 Wm(-1) K(-1) to approximately 7.6 Wm(-1) K(-1)). Thermal conductivity reduction in HPT-processed silicon is attributed to the formation of nanograin boundaries and metastable Si-III/XII phases which act as phonon scattering sites, and because of a large density of lattice defects introduced by HPT processing. Annealing the samples at 873 K increases the thermal conductivity due to the reduction in the density of secondary phases and lattice defects.

  11. Optimization of oxidation processes to improve crystalline silicon solar cell emitters

    Directory of Open Access Journals (Sweden)

    L. Shen

    2014-02-01

    Full Text Available Control of the oxidation process is one key issue in producing high-quality emitters for crystalline silicon solar cells. In this paper, the oxidation parameters of pre-oxidation time, oxygen concentration during pre-oxidation and pre-deposition and drive-in time were optimized by using orthogonal experiments. By analyzing experimental measurements of short-circuit current, open circuit voltage, series resistance and solar cell efficiency in solar cells with different sheet resistances which were produced by using different diffusion processes, we inferred that an emitter with a sheet resistance of approximately 70 Ω/□ performed best under the existing standard solar cell process. Further investigations were conducted on emitters with sheet resistances of approximately 70 Ω/□ that were obtained from different preparation processes. The results indicate that emitters with surface phosphorus concentrations between 4.96 × 1020 cm−3 and 7.78 × 1020 cm−3 and with junction depths between 0.46 μm and 0.55 μm possessed the best quality. With no extra processing, the final preparation of the crystalline silicon solar cell efficiency can reach 18.41%, which is an increase of 0.4%abs compared to conventional emitters with 50 Ω/□ sheet resistance.

  12. Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.; Aziz, Michael J.; Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Rekemeyer, Paul H.; Gradečak, Silvija [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-12-14

    Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

  13. Surface chemical-bonds analysis of silicon particles from diamond-wire cutting of crystalline silicon

    Science.gov (United States)

    Benayad, Anass; Hajjaji, Hamza; Coustier, Fabrice; Benmansour, Malek; Chabli, Amal

    2016-12-01

    The recycling of the Si powder resulting from the kerf loss during silicon ingot cutting into wafers for photovoltaic application shows both significant and achievable economic and environmental benefits. A combined x-ray photoelectron spectroscopy (XPS), attenuated total reflection (ATR)-Fourier transform infrared (FTIR) and micro-Raman spectral analyses were applied to kerf-loss Si powders reclaimed from the diamond wire cutting using different cutting fluids. These spectroscopies performed in suitable configurations for the analysis of particles, yield detailed insights on the surface chemical properties of the powders demonstrating the key role of the cutting fluid nature. A combined XPS core peak, plasmon loss, and valence band study allow assessing a qualitative and quantitative chemical, structural change of the kerf-loss Si powders. The relative contribution of the LO and TO stretching modes to the Si-O-Si absorption band in the ATR-FTIR spectra provide a consistent estimation of the effective oxidation level of the Si powders. The change in the cutting media from deionized water to city water, induces a different silicon oxide layer thickness at the surface of the final kerf-loss Si, depending on the powder reactivity to the media. The surfactant addition induces an enhanced carbon contamination in the form of grafted carbonated species on the surface of the particles. The thickness of the modified surface, depending on the cutting media, was estimated based on a simple model derived from the combined XPS core level and plasmon peak intensities. The effective nature of these carbonated species, sensitive to the water quality, was evidenced based on coupled XPS core peak and valence band study. The present work paves the way to a controlled process to reclaim the kerf-loss Si powder without heavy chemical etching steps.

  14. Laser fabrication of crystalline silicon nanoresonators from an amorphous film for low-loss all-dielectric nanophotonics

    CERN Document Server

    Dmitriev, P A; Milichko, V A; Mukhin, I S; Gudovskikh, A S; Sitnikova, A A; Samusev, A K; Krasnok, A E; Belov, P A

    2015-01-01

    The concept of high refractive index subwavelength dielectric nanoresonators, supporting electric and magnetic optical resonances, is a promising platform for waveguiding, sensing, and nonlinear nanophotonic devices. However, high concentration of defects in the nanoresonators diminishes their resonant properties, which are crucially dependent on their internal losses. Therefore, it seems to be inevitable to use initially crystalline materials for fabrication of the nanoresonators. Here, we show that the fabrication of crystalline (low-loss) resonant silicon nanoparticles by femtosecond laser ablation of amorphous (high-loss) silicon thin films is possible. We apply two conceptually different approaches: recently proposed laser-induced transfer and a novel laser writing technique for large-scale fabrication of the crystalline nanoparticles. The crystallinity of the fabricated nanoparticles is proven by Raman spectroscopy and electron transmission microscopy, whereas optical resonant properties of the nanopart...

  15. Laser fabrication of crystalline silicon nanoresonators from an amorphous film for low-loss all-dielectric nanophotonics

    Science.gov (United States)

    Dmitriev, P. A.; Makarov, S. V.; Milichko, V. A.; Mukhin, I. S.; Gudovskikh, A. S.; Sitnikova, A. A.; Samusev, A. K.; Krasnok, A. E.; Belov, P. A.

    2016-02-01

    The concept of high refractive index subwavelength dielectric nanoresonators, supporting electric and magnetic optical resonance, is a promising platform for waveguiding, sensing, and nonlinear nanophotonic devices. However, high concentration of defects in the nanoresonators diminishes their resonant properties, which are crucially dependent on their internal losses. Therefore, it seems to be inevitable to use initially crystalline materials for fabrication of the nanoresonators. Here, we show that the fabrication of crystalline (low-loss) resonant silicon nanoparticles by femtosecond laser ablation of amorphous (high-loss) silicon thin films is possible. We apply two conceptually different approaches: recently proposed laser-induced transfer and a novel laser writing technique for large-scale fabrication of the crystalline nanoparticles. The crystallinity of the fabricated nanoparticles is proven by Raman spectroscopy and electron transmission microscopy, whereas optical resonant properties of the nanoparticles are studied using dark-field optical spectroscopy and full-wave electromagnetic simulations.

  16. Modeling the splitting of thin silicon films from porosified crystalline silicon upon high temperature annealing in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ghannam, Moustafa Y.; Raheem, Yaser Abdul; Alomar, Abdul Azeez [EE Department, College of Engineering and Petroleum, Kuwait University, Safat (Kuwait); Poortmans, Jef [IMEC, Leuven (Belgium)

    2012-10-15

    The role of hydrogen in promoting thin film splitting from crystalline silicon wafers with pores or trenches during high temperature annealing is investigated. During the treatment, trenches are transformed into spherical voids that may laterally channel and split off the substrate. It is shown that the conditions necessary for hydrogen to contribute to the establishment of high stress levels around transformed voids or of pressure inside the voids are usually not satisfied. Hence promoting void coalescence by substantial void volume growth resulting from stress enhanced vacancy diffusion and/or exfoliation of separated voids are unlikely to occur. Also, there are no experimental evidence that confirms the role of hydrogen in triggering premature void collapse by Griffith fracture at relatively lower stress levels in conjunction with reduced surface energy. Therefore, it is concluded that splitting occurs during high temperature annealing only when neighboring voids are close enough to systematically coalesce. In that case, hydrogen may react at high temperature with the internal silicon surface of the voids (walls) and contribute to breaking the thin straps separating the voids which promotes channelling and film splitting (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Mitigating mechanical failure of crystalline silicon electrodes for lithium batteries by morphological design.

    Science.gov (United States)

    An, Yonghao; Wood, Brandon C; Ye, Jianchao; Chiang, Yet-Ming; Wang, Y Morris; Tang, Ming; Jiang, Hanqing

    2015-07-21

    Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous LixSi alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteract the anisotropy in the crystalline/amorphous interface velocity. This produces a much more uniform volume expansion, significantly reducing strain concentration. Based on a new, validated methodology that improves previous models of anisotropic swelling of c-Si, we propose optimal morphological designs for c-Si pillars and particles. The advantages of the new morphologies are clearly demonstrated by mesoscale simulations and verified by experiments on engineered c-Si micropillars. The results of this study illustrate that morphological design is effective in improving the fracture resistance of micron-sized Si electrodes, which will facilitate their practical application in next-generation Li-ion batteries. The model and design approach present in this paper also have general implications for the study and mitigation of mechanical failure of electrode materials that undergo large anisotropic volume change upon ion insertion and extraction.

  18. Correlation Between the Raman Crystallinity of p-Type Micro-Crystalline Silicon Layer and Open Circuit Voltage of n-i-p Solar Cells.

    Science.gov (United States)

    Jung, Junhee; Kim, Sunbo; Park, Jinjoo; Shin, Chonghoon; Pham, Duy Phong; Kim, Jiwoong; Chung, Sungyoun; Lee, Youngseok; Yi, Junsin

    2015-10-01

    This article mainly discusses the difference between p-i-n and n-i-p type solar cells. Their structural difference has an effect on cell performance, such as open circuit voltage and fill factor. Although the deposition conditions are the same for both p-i-n and n-i-p cases, the substrate layers for depositing p-type microcrystalline silicon layers differ. In n-i-p cells, the substrate layer is p-type amorphous silicon oxide layer; whereas, in p-i-n cells, the substrate layer is ZnO:Al. The interfacial change leads to a 12% difference in the crystallinity of the p-type microcrystalline silicon layers. When the p-type microcrystalline silicon layer's crystallinity was not sufficient to activate an internal electric field, the open circuit voltage and fill factor decreased 0.075 V and 7.36%, respectively. We analyzed this problem by comparing the Raman spectra, electrical conductivity, activation energy and solar cell performance. By adjusting the thickness of the p-type microcrystalline silicon layer, we increased the open circuit voltage of the n-i-p cell from 0.835 to 0.91 V.

  19. The Synthesis and Structural Properties of Crystalline Silicon Quantum Dots upon Thermal Annealing of Hydrogenated Amorphous Si-Rich Silicon Carbide Films

    Science.gov (United States)

    Wen, Guozhi; Zeng, Xiangbin; Li, Xianghu

    2016-08-01

    Silicon quantum dots (QDs) embedded in non-stoichiometric hydrogenated silicon carbide (SiC:H) thin films have been successfully synthesized by plasma-enhanced chemical vapor deposition and post-annealing. The chemical composition analyses have been carried out by x-ray photoelectron spectroscopy (XPS). The bonding configurations have been deduced from Fourier transform infrared absorption measurements (FTIR). The evolution of microstructure with temperature has been characterized by glancing incident x-ray diffraction (XRD) and Raman diffraction spectroscopy. XPS and FTIR show that it is in Si-rich feature and there are a few hydrogenated silicon clusters in the as-grown sample. XRD and Raman diffraction spectroscopy show that it is in amorphous for the as-grown sample, while crystalline silicon QDs have been synthesized in the 900°C annealed sample. Silicon atoms precipitation from the SiC matrix or silicon phase transition from amorphous SiC is enhanced with annealing temperature increase. The average sizes of silicon QDs are about 5.1 nm and 5.6 nm, the number densities are as high as 1.7 × 1012 cm-2 and 3.2 × 1012 cm-2, and the crystalline volume fractions are about 58.3% and 61.3% for the 900°C and 1050°C annealed samples, respectively. These structural properties analyses provide an understanding about the synthesis of silicon QDs upon thermal annealing for applications in next generation optoelectronic and photovoltaic devices.

  20. Silicon Dioxide Coating Deposited by PDPs on PET Films and Influence on Oxygen Transmission Rate

    Institute of Scientific and Technical Information of China (English)

    SUN Yun-Jin; FU Ya-Bo; CHEN Qiang; ZHANG Chun-Mei; SANG Li-Jun; ZHANG Yue-Fei

    2008-01-01

    A silicon dioxide film is deposited on the polyethyleneterephtalate (PET) by a penning discharge plasma source at ambient temperature in a high vacuum chamber.Hexamethyldisiloxane and oxygen are adopted as precursor and reactive reagent to grow a nano-scale silicon dioxide layer on polymer surfaces.For the chemical structure analysis x-ray photoelectron spectroscopy is performed to demonstrate the content of Si,0 and C elements.It is noticed that a higher silicon concentration is contained if Ar plasma is used for pretreatment.X-ray diffraction analysis shows that a micro-crystal silicon dioxide is formed by peak patterns at 25.84° and 21.8°.The barrier properties examined by oxygen transmission rate show that the permeation parameter of the 12-μm-thick PET film drastically decreases from 135 cc/m2 per day for the control one to 0.713 cc/m2 per day for the as-deposited one after Ar plasma treatment.The surface morphology related to the barrier properties of SiOx-coated polymers os also investigated by scanning electron microscopy and atomic force microscopy.

  1. Improving the performance of amorphous and crystalline silicon heterojunction solar cells by monitoring surface passivation

    Energy Technology Data Exchange (ETDEWEB)

    Schuettauf, J.W.A.; Van der Werf, C.H.M.; Kielen, I.M.; Van Sark, W.G.J.H.M.; Rath, J.K.; Schropp, R.E.I. [Utrecht University, Debye Institute for Nanomaterials Science, Nanophotonics, Physics of Devices, Princetonplein 5, 3584 CC Utrecht (Netherlands)

    2012-09-15

    The influence of thermal annealing on the crystalline silicon surface passivating properties of selected amorphous silicon containing layer stacks (including intrinsic and doped films), as well as the correlation with silicon heterojunction solar cell performance has been investigated. All samples have been isochronally annealed for 1 h in an N{sub 2} ambient at temperatures between 150C and 300C in incremental steps of 15C. For intrinsic films and intrinsic/n-type stacks, an improvement in passivation quality is observed up to 255C and 270C, respectively, and a deterioration at higher temperatures. For intrinsic/n-type a-Si:H layer stacks, a maximum minority carrier lifetime of 13.3 ms at an injection level of 10{sup 15} cm{sup -3} has been measured. In contrast, for intrinsic/p-type a-Si:H layer stacks, a deterioration in passivation is observed upon annealing over the whole temperature range. Comparing the lifetime values and trends for the different layer stacks to the performance of the corresponding cells, it is inferred that the intrinsic/p-layer stack is limiting device performance. Furthermore, thermal annealing of p-type layers should be avoided entirely. We therefore propose an adapted processing sequence, leading to a substantial improvement in efficiency to 16.7%, well above the efficiency of 15.8% obtained with the 'standard' processing sequence.

  2. Nickel Electroless Plating: Adhesion Analysis for Mono-Type Crystalline Silicon Solar Cells.

    Science.gov (United States)

    Shin, Eun Gu; Rehman, Atteq ur; Lee, Sang Hee; Lee, Soo Hong

    2015-10-01

    The adhesion of the front electrodes to silicon substrate is the most important parameters to be optimized. Nickel silicide which is formed by sintering process using a silicon substrate improves the mechanical and electrical properties as well as act as diffusion barrier for copper. In this experiment p-type mono-crystalline czochralski (CZ) silicon wafers having resistivity of 1.5 Ω·cm were used to study one step and two step nickel electroless plating process. POCl3 diffusion process was performed to form the emitter with the sheet resistance of 70 ohm/sq. The Six, layer was set down as an antireflection coating (ARC) layer at emitter surface by plasma enhanced chemical vapor deposition (PECVD) process. Laser ablation process was used to open SiNx passivation layer locally for the formation of the front electrodes. Nickel was deposited by electroless plating process by one step and two step nickel electroless deposition process. The two step nickel plating was performed by applying a second nickel deposition step subsequent to the first sintering process. Furthermore, the adhesion analysis for both one step and two steps process was conducted using peel force tester (universal testing machine, H5KT) after depositing Cu contact by light induced plating (LIP).

  3. Free Energy Minimization Calculation of Complex Chemical Equilibria. Reduction of Silicon Dioxide with Carbon at High Temperature.

    Science.gov (United States)

    Wai, C. M.; Hutchinson, S. G.

    1989-01-01

    Discusses the calculation of free energy in reactions between silicon dioxide and carbon. Describes several computer programs for calculating the free energy minimization and their uses in chemistry classrooms. Lists 16 references. (YP)

  4. Aluminum-jointed silicon dioxide octagon nanohelix array with desired complex refractive index.

    Science.gov (United States)

    Jen, Yi-Jun; Chen, Chien-Chi; Jheng, Ci-Yao

    2014-06-15

    In this Letter, glancing angle deposition is used to form an aluminum-jointed silicon dioxide octagon nanohelix array as a 3D nanostructured thin film. As a sculptured metal-dielectric composite, the film exhibits a complex refractive index of near unity with a small imaginary part. This structured film is demonstrated as an efficient light absorber to absorb light in a broad band and over a wide range of angles for both polarization states.

  5. Study of an Amorphous Silicon Oxide Buffer Layer for p-Type Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells and Their Temperature Dependence

    Directory of Open Access Journals (Sweden)

    Taweewat Krajangsang

    2014-01-01

    Full Text Available Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H films were used as front and rear buffer layers in crystalline silicon heterojunction (c-Si-HJ solar cells. The surface passivity and effective lifetime of these i-a-SiO:H films on an n-type silicon wafer were improved by increasing the CO2/SiH4 ratios in the films. Using i-a-SiO:H as the front and rear buffer layers in c-Si-HJ solar cells was investigated. The front i-a-SiO:H buffer layer thickness and the CO2/SiH4 ratio influenced the open-circuit voltage (Voc, fill factor (FF, and temperature coefficient (TC of the c-Si-HJ solar cells. The highest total area efficiency obtained was 18.5% (Voc=700 mV, Jsc=33.5 mA/cm2, and FF=0.79. The TC normalized for this c-Si-HJ solar cell efficiency was −0.301%/°C.

  6. Nanometric Cutting of Silicon with an Amorphous-Crystalline Layered Structure: A Molecular Dynamics Study

    Science.gov (United States)

    Wang, Jinshi; Fang, Fengzhou; Zhang, Xiaodong

    2017-01-01

    Materials with specific nanometric layers are of great value in both theoretical and applied research. The nanometric layer could have a significant influence on the response to the mechanical loading. In this paper, the nanometric cutting on the layered systems of silicon has been studied by molecular dynamics. This kind of composite structure with amorphous layer and crystalline substrate is important for nanomachining. Material deformation, stress status, and chip formation, which are the key issues in nano-cutting, are analyzed. A new chip formation mechanism, i.e., the mixture of extrusion and shear, has been observed. In addition, from the perspective of engineering, some specific composite models show the desired properties due to the low subsurface damage or large material removal rate. The results enrich the cutting theory and provide guidance on nanometric machining.

  7. Dual interface gratings design for absorption enhancement in thin crystalline silicon solar cells

    Science.gov (United States)

    Zhang, Jinqiannan; Yu, Zhongyuan; Liu, Yumin; Chai, Hongyu; Hao, Jing; Ye, Han

    2017-09-01

    We numerically study and analyze the light absorption enhancement in thin crystalline silicon solar cell with dual interface gratings. The structure combines the front dielectric nanowalls and the sinusoidal plasmonic grating at back reflector. We show that having specific interfaces with well-chosen period, fill factor and height can allow more efficient dielectric and plasmonic modes coupling into active layer and can improve the solar cell performance. For 1 μm active layer case, the optimal result for the proposed structure achieves short-circuit current of 23.6 mA/cm2, which performs over 50% better than flat solar cell structure, the short-circuit current of which is 15.5 mA/cm2. In addition, the active layer thickness and angular analysis show that the proposed structure maintains its advantage over flat structure.

  8. Phase field modeling of grain structure evolution during directional solidification of multi-crystalline silicon sheet

    Science.gov (United States)

    Lin, H. K.; Lan, C. W.

    2017-10-01

    Evolution of grain structures and grain boundaries (GBs), especially the coincident site lattice GBs, during directional solidification of multi-crystalline silicon sheet are simulated by using a phase field model for the first time. Since the coincident site lattice GBs having lower mobility, tend to follow their own crystallographic directions despite thermal gradients, the anisotropic energy and mobility of GBs are considered in the model. Three basic interactions of GBs during solidification are examined and they are consistent with experiments. The twinning process for new grain formation is further added in the simulation by considering twin nucleation. The effect of initial distribution of GB types and grain orientations is also investigated for the twinning frequency and the evolution of grain size and GB types.

  9. Highly efficient crystalline silicon/Zonyl fluorosurfactant-treated organic heterojunction solar cells

    Science.gov (United States)

    Liu, Qiming; Ono, Masahiro; Tang, Zeguo; Ishikawa, Ryo; Ueno, Keiji; Shirai, Hajime

    2012-04-01

    We demonstrate a highly efficient hybrid crystalline silicon (c-Si) based photovoltaic devices with hole-transporting transparent conductive poly-(3,4-ethlenedioxythiophene):poly(styrenesufonic acid) (PEDOT:PSS) films, incorporating a Zonyl fluorosurfactant as an additive, compared to non additive devices. The usage of a 0.1% Zonly treated PEDOT:PSS improved the adhesion of precursor solution on hydrophobic c-Si wafer without any oxidation process. The average power conversion efficiency η value was 10.8%-11.3%, which was superior to those of non-treated devices. Consequently, c-Si/Zonyl-treated PEDOT:PSS heterojunction devices exhibited the highest η of 11.34%. The Zonyl-treated soluble PEDOT:PSS composite is promising as a hole-transporting transparent conducting layer for c-Si/organic photovoltaic applications.

  10. An overview of crystalline silicon solar cell technology: Past, present, and future

    Science.gov (United States)

    Sopian, K.; Cheow, S. L.; Zaidi, S. H.

    2017-09-01

    Crystalline silicon (c-Si) solar cell, ever since its inception, has been identified as the only economically and environmentally sustainable renewable resource to replace fossil fuels. Performance c-Si based photovoltaic (PV) technology has been equal to the task. Its price has been reduced by a factor of 250 over last twenty years (from ˜ 76 USD to ˜ 0.3 USD); its market growth is expected to reach 100 GWP by 2020. Unfortunately, it is still 3-4 times higher than carbon-based fuels. With the matured PV manufacturing technology as it exists today, continuing price reduction poses stiff challenges. Alternate manufacturing approaches in combination with thin wafers, low (cost-based analysis of advanced solar cell manufacturing technologies aimed at higher (˜ 22 %) efficiency with existing equipment and processes.

  11. Band Discontinuities in Gallium Phosphide/Crystalline Silicon Heterojunctions Studied by Internal Photoemission

    Science.gov (United States)

    Sakata, Isao; Kawanami, Hitoshi

    2008-09-01

    We measured the band lineup of gallium phosphide (GaP) on crystalline silicon (c-Si) heterojunctions (HJs) by using internal photoemission (IPE), where the heterojunctions were prepared by using solid-source molecular beam epitaxy. It was found that the conduction-band and valence-band discontinuities, denoted by ΔEc and ΔEv, are 0.09+/-0.01 and 1.05+/-0.01 eV, respectively. By performing measurements on samples with different GaP layer thicknesses, we clarified that ΔEv of the present GaP-on-Si HJs is not affected by strain normal to the growth direction. The values of ΔEc and ΔEv obtained for the GaP-on-Si HJs are significantly different from those reported for thin Si-on-GaP HJs, and the implications of this discrepancy are briefly discussed.

  12. Atomistic simulations of surface coverage effects in anisotropic wet chemical etching of crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gosalvez, M.A.; Foster, A.S.; Nieminen, R.M

    2002-12-30

    Atomistic simulations of anisotropic wet chemical etching of crystalline silicon have been performed in order to determine the dependence of the etch rates of different crystallographic orientations on surface coverage and clustering of OH radicals. We show that the etch rate is a non-monotonic function of OH coverage and that there always exists a coverage value at which the etch rate reaches a maximum. The dependence of the anisotropy of the etching process on coverage, including the dependence of the fastest-etched plane orientation, is implicitly contained in the model and predictions of convex corner under-etching structures are made. We show that the whole etching process is controlled by only a few surface configurations involving a particular type of next-nearest neighbours. The relative value of the removal probabilities of these confitions determines the balance in the occurrence of step propagation and etch pitting for all surface orientations.

  13. Periodic surface structures on crystalline silicon created by 532 nm picosecond Nd:YAG laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Trtica, M.S. [Physical Chemistry Department, Vinca Institute of Nuclear Sciences, P.O. BOX 522, 11001 Belgrade (Serbia)], E-mail: etrtica@vin.bg.ac.yu; Gakovic, B.M. [Atomic Physics Department, Vinca Institute of Nuclear Sciences, P.O. BOX 522, 11001 Belgrade (Serbia); Radak, B.B. [Physical Chemistry Department, Vinca Institute of Nuclear Sciences, P.O. BOX 522, 11001 Belgrade (Serbia); Batani, D.; Desai, T.; Bussoli, M. [Dipartimento di Fisica ' G. Occhialini' , Universita degli Studi di Milano Bicocca, Piazza della Scienza 3, 20126 Milano (Italy)

    2007-12-30

    Creation of laser-induced morphology features, particularly laser-induced periodic surface structures (LIPSS), by a 532 nm picosecond Nd:YAG laser on crystalline silicon is reported. The LIPSS, often termed ripples, were produced at average laser irradiation fluences of 0.7, 1.6, and 7.9 J cm{sup -2}. Two types of ripples were registered: micro-ripples (at micrometer scale) in the form of straight parallel lines extending over the entire irradiated spot, and nano-ripples (at nanometer scale), apparently concentric, registered only at the rim of the spot, with the periodicity dependent on laser fluence. There are indications that the parallel ripples are a consequence of the partial periodicity contained in the diffraction modulated laser beam, and the nano-ripples are very likely frozen capillary waves. The damage threshold fluence was estimated at 0.6 J cm{sup -2}.

  14. Summary of the 4th Workshop on Metallization for Crystalline Silicon Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Beaucarne, G. [Dow Corning, Parc Industriel, Zone C, Rue Jules Bordet, 7180 Seneffe (Belgium); Schubert, G. [Sunways AG, Macairestrasse 3 - 5, D - 78467 Konstanz (Germany); Hoornstra, J. [Energy research Centre of the Netherlands ECN, POBox 1, 1755 ZG Petten (Netherlands)

    2013-07-01

    The 4th Metallization Workshop held in May 2013 in Constance, Germany, enabled experts in metallization for crystalline silicon solar cells to obtain a clear view on the status of the technology, as well as to exchange and generate new ideas and insights. From the contributions on the workshop, it was clear that the traditional metallization technique of screenprinting Ag paste has been improved in a dramatic way over the last two years, accelerating the decrease of Ag consumption per cell while improving solar cell efficiency. This was achieved through enhanced understanding of screenprinted contacts, improving Ag pastes and evolutionary modifications to the screenprinting technique. Alternatives to screenprinting, including electroplating of Ni and Cu contacts, also continue to progress, though not quite at the same impressive rate of improvement as Ag printing.

  15. DLTS properties of iron defects in crystalline silicon used in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hamadeh, H. [Department of Physics, Atomic Energy Commission of Syria, Solar Cell Group, P.O. Box 6091, Damascus (Syrian Arab Republic)]. E-mail: hhamadeh@aecs.org.sy; Darwich, R. [Department of Physics, Atomic Energy Commission of Syria, Solar Cell Group, P.O. Box 6091, Damascus (Syrian Arab Republic)

    2004-10-25

    Crystalline silicon used in solar cells has been investigated using deep level transient spectroscopy (DLTS). In majority-carrier pulse sequence an interstitial iron deep level was observed. However, the investigation of this deep level peak with different filling pulsewidths shows that this level consists of two superimposed levels. The activation energies of these levels are 375 meV (F{sub 1}) and 480 meV (F{sub 2}). The capture cross section of the level (F{sub 1}) with the lower activation energy is nearly two orders of magnitude larger than the capture cross section of defect F{sub 2}. Both capture cross sections show, over a wide range, no temperature dependence indicating that nonradiative recombination mechanisms other than multiphonon emission are involved. The concentration ratio between both defects is nearly 1:2.

  16. Heterogeneous reduction of carbon dioxide by hydride-terminated silicon nanocrystals

    Science.gov (United States)

    Sun, Wei; Qian, Chenxi; He, Le; Ghuman, Kulbir Kaur; Wong, Annabelle P. Y.; Jia, Jia; Jelle, Abdinoor A.; O'Brien, Paul G.; Reyes, Laura M.; Wood, Thomas E.; Helmy, Amr S.; Mims, Charles A.; Singh, Chandra Veer; Ozin, Geoffrey A.

    2016-08-01

    Silicon constitutes 28% of the earth's mass. Its high abundance, lack of toxicity and low cost coupled with its electrical and optical properties, make silicon unique among the semiconductors for converting sunlight into electricity. In the quest for semiconductors that can make chemicals and fuels from sunlight and carbon dioxide, unfortunately the best performers are invariably made from rare and expensive elements. Here we report the observation that hydride-terminated silicon nanocrystals with average diameter 3.5 nm, denoted ncSi:H, can function as a single component heterogeneous reducing agent for converting gaseous carbon dioxide selectively to carbon monoxide, at a rate of hundreds of μmol h-1 g-1. The large surface area, broadband visible to near infrared light harvesting and reducing power of SiH surface sites of ncSi:H, together play key roles in this conversion. Making use of the reducing power of nanostructured hydrides towards gaseous carbon dioxide is a conceptually distinct and commercially interesting strategy for making fuels directly from sunlight.

  17. In-Situ Measurement of Power Loss for Crystalline Silicon Modules Undergoing Thermal Cycling and Mechanical Loading Stress Testing

    DEFF Research Database (Denmark)

    Spataru, Sergiu; Hacke, Peter; Sera, Dezso

    We analyze the degradation of multi-crystalline silicon photovoltaic modules undergoing simultaneous thermal, mechanical, and humidity-freeze stress testing to develop a dark environmental chamber in-situ measurement procedure for determining module power loss. We analyze dark I-V curves measured...

  18. Atomic-Resolution Observations of Semi-Crystalline IntegranularThin Films in Silicon Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Alexander; Idrobo, Juan C.; Cinibulk, Michael K.; Kisielowski, Christian; Browning, Nigel D.; Ritchie, Robert O.

    2005-08-01

    The thin intergranular phase in a silicon nitride (Si3N4)ceramic, which has been regarded for decades as having an entirely amorphous morphology, is shown to have a semi-crystalline structure. Using two different but complementary high-resolution electron microscopy methods, the intergranular atomic structure was directly imaged at the atomic level. These high-resolution images show that the atomic arrangement of the dopand element cerium takes very periodic positions not only along the interface between the intergranular phase and the Si3N4 matrix grains, but it arranges in a semi-crystalline structure that spans the entire width of the intergranular phase between two adjacent matrix grains, in principle connecting the two separate matrix grains. The result will have implications on the approach of understanding the materials properties of ceramics, most significantly on the mechanical properties and the associated computational modeling of the atomic structure of the thin intergranular phase in Si3N4 ceramics.

  19. Fabrication of amorphous micro-ring arrays in crystalline silicon using ultrashort laser pulses

    Science.gov (United States)

    Fuentes-Edfuf, Yasser; Garcia-Lechuga, Mario; Puerto, Daniel; Florian, Camilo; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan

    2017-05-01

    We demonstrate a simple way to fabricate amorphous micro-rings in crystalline silicon using direct laser writing. This method is based on the fact that the phase of a thin surface layer can be changed into the amorphous phase by irradiation with a few ultrashort laser pulses (800 nm wavelength and 100 fs duration). Surface-depressed amorphous rings with a central crystalline disk can be fabricated without the need for beam shaping, featuring attractive optical, topographical, and electrical properties. The underlying formation mechanism and phase change pathway have been investigated by means of fs-resolved microscopy, identifying fluence-dependent melting and solidification dynamics of the material as the responsible mechanism. We demonstrate that the lateral dimensions of the rings can be scaled and that the rings can be stitched together, forming extended arrays of structures not limited to annular shapes. This technique and the resulting structures may find applications in a variety of fields such as optics, nanoelectronics, and mechatronics.

  20. Study of the diffusion of points defects in crystalline silicon using the kinetic ART method

    Science.gov (United States)

    Trochet, Mickael; Brommer, Peter; Beland, Laurent-Karim; Joly, Jean-Francois; Mousseau, Normand

    2013-03-01

    Because of the long-time scale involved, the activated diffusion of point defects is often studied in standard molecular dynamics at high temperatures only, making it more difficult to characterize complex diffusion mechanisms. Here, we turn to the study of point defect diffusion in crystalline silicon using kinetic ART (kART), an off-lattice kinetic Monte Carlo method with on-the-fly catalog building based on the activation-relaxation technique (ART nouveau). By generating catalogs of diffusion mechanisms and fully incorporating elastic and off-lattice effects, kART is a unique tool for characterizing this problem. More precisely, using kART with the standard Stillinger-Weber potential we consider the evolution of crystalline cells with 1 to 4 vacancies and 1 to 4 interstitials at various temperatures and to provide a detailed picture of both the atomistic diffusion mechanisms and overall kinetics in addition to identifying special configurations such as a 2-interstitial super-diffuser.

  1. Diffusion of point defects in crystalline silicon using the kinetic activation-relaxation technique method

    Science.gov (United States)

    Trochet, Mickaël; Béland, Laurent Karim; Joly, Jean-François; Brommer, Peter; Mousseau, Normand

    2015-06-01

    We study point-defect diffusion in crystalline silicon using the kinetic activation-relaxation technique (k-ART), an off-lattice kinetic Monte Carlo method with on-the-fly catalog building capabilities based on the activation-relaxation technique (ART nouveau), coupled to the standard Stillinger-Weber potential. We focus more particularly on the evolution of crystalline cells with one to four vacancies and one to four interstitials in order to provide a detailed picture of both the atomistic diffusion mechanisms and overall kinetics. We show formation energies, activation barriers for the ground state of all eight systems, and migration barriers for those systems that diffuse. Additionally, we characterize diffusion paths and special configurations such as dumbbell complex, di-interstitial (IV-pair+2I) superdiffuser, tetrahedral vacancy complex, and more. This study points to an unsuspected dynamical richness even for this apparently simple system that can only be uncovered by exhaustive and systematic approaches such as the kinetic activation-relaxation technique.

  2. Combined Effect of Mechanical Grooving and Stain-Etched Surface on Optical and Electrical Properties of Crystalline Silicon Substrates

    Science.gov (United States)

    Zarroug, Ahmed; Derbali, Lotfi; Ouertani, Rachid; Dimassi, Wissem; Ezzaouia, Hatem

    2014-05-01

    This paper investigates the combined effect of mechanical grooving and porous silicon (PS) on the front surface reflectance and the electronic properties of crystalline silicon substrates. Mechanical surface texturization leads to reduce the cell reflectance, enhance the light trapping and augment the carrier collection probability. PS was introduced as an efficient antireflective coating (ARC) onto the front surface of crystalline silicon solar cell. Micro-periodic V-shaped grooves were made by means of a micro-groove machining process prior to junction formation. Subsequently, wafers were subjected to an isotropic potassium hydroxide (KOH) etching so that the V-shape would be turned to a U-shape. We found that the successive treatment of silicon surfaces with stain-etching, grooving then alkaline etching enhances the absorption of the textured surface, and decreases the reflectance from 35% to 7% in the 300-1200 nm wavelength range. We obtained a significant increase in the overall light path that generates the building up of the light trapping inside the substrate. We found an improvement in the illuminated I-V characteristics and an increase in the minority carrier lifetime τeff. Such a simple method was adopted to effectively reinforce the overall device performance of crystalline silicon-based solar cells.

  3. Study on the SiN_x/Al rear reflectance performance of crystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The performance of internal rear surface reflectance of crystalline silicon solar cells is becoming more and more important with the decrease of thickness of the silicon wafers. In this paper PC1D was used to simulate the correlations between the rear surface reflectance and the electrical as well as optical properties of the solar cells. The results showed that the short circuit current, open circuit voltage and quantum efficiency were all enhanced with the increase of the rear reflectance. When the rear reflectance increased from 60% to 100%, the short circuit current, open circuit voltage and maximum output power were improved by about 0.128 A, 0.007 V, and 0.066 W, respectively. The internal quantum efficiency was improved by 39.9%, the external quantum increased by 17.4%, and the efficiency of the solar cells was enhanced by 0.4% at 1100 nm wavelength. The screen-printing was selected to prepare SiNx/Al reflector, and experimental results showed that the SiNx/Al reflector has desired characteristic of internal rear reflectance, with the reflectivity of 15% higher than that of conventional aluminum BSF at 1100 nm wavelength.

  4. The emergence of high-performance multi-crystalline silicon in photovoltaics

    Science.gov (United States)

    Lan, C. W.; Lan, A.; Yang, C. F.; Hsu, H. P.; Yang, M.; Yu, A.; Hsu, B.; Hsu, W. C.; Yang, A.

    2017-06-01

    The emergence of the high-performance multi-crystalline silicon (HP mc-Si) in 2011 has made a significant impact to photovoltaic industry. In addition to the much better ingot uniformity and production yield, HP mc-Si also has better material quality for solar cells. As a result, the average efficiency of solar cells made from HP mc-Si in production increased from 16.6% in 2011 to 18.5% or beyond in 2016. More importantly, the efficiency distribution became much narrower; the difference from various producers became smaller as well. Unlike the conventional way of having large grains and electrically-inactive twin boundaries, the crystal growth of HP mc-Si by directional solidification is initiated from uniform small grains having a high fraction of random grain boundaries. The grains developed from such grain structures significantly relax thermal stress and suppress the massive generation and propagation of dislocation clusters. The gettering efficacy of HP mc-Si is also superior to the conventional one. Nowadays, most of commercial mc-Si is grown by this approach, which could be implemented by either seeded with silicon particles or controlled nucleation, e.g., using nucleation agent coating. The future improvement of this technology will also be discussed in this review.

  5. Sprayed and Spin-Coated Multilayer Antireflection Coating Films for Nonvacuum Processed Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Abdullah Uzum

    2017-01-01

    Full Text Available Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fabricated using CZ-Si p-type wafers in three sets: (1 without antireflection coating (ARC layer, (2 with TiO2-compact ARC film, and (3 with ZrO2-polymer composite/TiO2-compact multilayer ARC film. Conversion efficiency of the cells improved by a factor of 0.8% (from 15.19% to 15.88% owing to the multilayer ARC. Jsc was improved further by 2 mA cm−2 (from 35.3 mA cm−2 to 37.2 mA cm−2 when compared with a single TiO2-compact ARC.

  6. Band Offsets at the Interface between Crystalline and Amorphous Silicon from First Principles

    Science.gov (United States)

    Jarolimek, K.; Hazrati, E.; de Groot, R. A.; de Wijs, G. A.

    2017-07-01

    The band offsets between crystalline and hydrogenated amorphous silicon (a -Si ∶H ) are key parameters governing the charge transport in modern silicon heterojunction solar cells. They are an important input for macroscopic simulators that are used to further optimize the solar cell. Past experimental studies, using x-ray photoelectron spectroscopy (XPS) and capacitance-voltage measurements, have yielded conflicting results on the band offset. Here, we present a computational study on the band offsets. It is based on atomistic models and density-functional theory (DFT). The amorphous part of the interface is obtained by relatively long DFT first-principles molecular-dynamics runs at an elevated temperature on 30 statistically independent samples. In order to obtain a realistic conduction-band position the electronic structure of the interface is calculated with a hybrid functional. We find a slight asymmetry in the band offsets, where the offset in the valence band (0.29 eV) is larger than in the conduction band (0.17 eV). Our results are in agreement with the latest XPS measurements that report a valence-band offset of 0.3 eV [M. Liebhaber et al., Appl. Phys. Lett. 106, 031601 (2015), 10.1063/1.4906195].

  7. CMOS-compatible, athermal silicon ring modulators clad with titanium dioxide.

    Science.gov (United States)

    Djordjevic, Stevan S; Shang, Kuanping; Guan, Binbin; Cheung, Stanley T S; Liao, Ling; Basak, Juthika; Liu, Hai-Feng; Yoo, S J B

    2013-06-17

    We present the design, fabrication and characterization of athermal nano-photonic silicon ring modulators. The athermalization method employs compensation of the silicon core thermo-optic contribution with that from the amorphous titanium dioxide (a-TiO(2)) overcladding with a negative thermo-optic coefficient. We developed a new CMOS-compatible fabrication process involving low temperature RF magnetron sputtering of high-density and low-loss a-TiO(2) that can withstand subsequent elevated-temperature CMOS processes. Silicon ring resonators with 275 nm wide rib waveguide clad with a-TiO(2) showed near complete athermalization and moderate optical losses. Small-signal testing of the micro-resonator modulators showed high extinction ratio and gigahertz bandwidth.

  8. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography

    Science.gov (United States)

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-01

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga+ ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90–210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  9. Silicon dioxide with a silicon interfacial layer as an insulating gate for highly stable indium phosphide metal-insulator-semiconductor field effect transistors

    Science.gov (United States)

    Kapoor, V. J.; Shokrani, M.

    1991-01-01

    A novel gate insulator consisting of silicon dioxide (SiO2) with a thin silicon (Si) interfacial layer has been investigated for high-power microwave indium phosphide (InP) metal-insulator-semiconductor field effect transistors (MISFETs). The role of the silicon interfacial layer on the chemical nature of the SiO2/Si/InP interface was studied by high-resolution X-ray photoelectron spectroscopy. The results indicated that the silicon interfacial layer reacted with the native oxide at the InP surface, thus producing silicon dioxide, while reducing the native oxide which has been shown to be responsible for the instabilities in InP MISFETs. While a 1.2-V hysteresis was present in the capacitance-voltage (C-V) curve of the MIS capacitors with silicon dioxide, less than 0.1 V hysteresis was observed in the C-V curve of the capacitors with the silicon interfacial layer incorporated in the insulator. InP MISFETs fabricated with the silicon dioxide in combination with the silicon interfacial layer exhibited excellent stability with drain current drift of less than 3 percent in 10,000 sec, as compared to 15-18 percent drift in 10,000 sec for devices without the silicon interfacial layer. High-power microwave InP MISFETs with Si/SiO2 gate insulators resulted in an output power density of 1.75 W/mm gate width at 9.7 GHz, with an associated power gain of 2.5 dB and 24 percent power added efficiency.

  10. Crystalline SiCO: Implication on structure and thermochemistry of ternary silicon oxycarbide ceramics

    Science.gov (United States)

    Bodiford, Nelli

    The need for innovative refractory materials---materials that can sustain extreme temperatures---has been constantly growing within the modern industries. Basic requirements for usage at ultra-high-temperatures have been considered such as high melting point, high structural strength, exceptional resistance to oxidation, zero or almost zero creep. Monolithic ceramics alone cannot provide these properties, therefore, composite materials are sought to fulfill the demand. For example, silicon nitride and silicon carbide based ceramics have long been leading contenders for structural use in gas turbine engines. In the course of this work we are investigating amorphous SiCO formed via polymer-to-ceramic route. Previously a considerable amount of work has been done on structures of stoichiometric amorphous SiCO and a "perfect" random network was obtained (experimentally as well as supported by computational work) up to the phase content of 33 mol-% SiC. By "perfect" one assumes to have four fold coordinated Si atoms bonded to C and O; C atoms bond to Si atoms only and O is two fold connected to Si. Beyond 33 mol-% SiC within SiCO phase the structural imperfections and defects start to develop. Aside from the stoichiometric form of SiCO, the polymer-to-ceramic route allows for the incorporation of high molar amounts of carbon to create SiCO ceramic with excess carbon. The incorporation of carbon into silica glass improves high-temperature mechanical properties and increases resistance to crystallization of the amorphous material. The amount of 'free carbon' can be controlled through the choice of precursors used during synthesis. There were no ternary crystalline phases of SiCO observed. However, in systems such as MgO-SiO2, Na2O-Al2O 3-SiO2 there are ternary crystalline compounds (MgSiO 3, Mg2SiO4, NaAlSiO4, NaAlSi3 O8) that are of a greater energetic stability than glasses of the same composition. What makes the SiCO system different? In the approach proposed in this

  11. Hydrogen plasma treatment of silicon dioxide for improved silane deposition.

    Science.gov (United States)

    Gupta, Vipul; Madaan, Nitesh; Jensen, David S; Kunzler, Shawn C; Linford, Matthew R

    2013-03-19

    We describe a method for plasma cleaning silicon surfaces in a commercial tool that removes adventitious organic contamination and enhances silane deposition. As shown by wetting, ellipsometry, and XPS, hydrogen, oxygen, and argon plasmas effectively clean Si/SiO2 surfaces. However, only hydrogen plasmas appear to enhance subsequent low-pressure chemical vapor deposition of silanes. Chemical differences between the surfaces were confirmed via (i) deposition of two different silanes: octyldimethylmethoxysilane and butyldimethylmethoxysilane, as evidenced by spectroscopic ellipsometry and wetting, and (ii) a principal components analysis (PCA) of TOF-SIMS data taken from the different plasma-treated surfaces. AFM shows no increase in surface roughness after H2 or O2 plasma treatment of Si/SiO2. The effects of surface treatment with H2/O2 plasmas in different gas ratios, which should allow greater control of surface chemistry, and the duration of the H2 plasma (complete surface treatment appeared to take place quickly) are also presented. We believe that this work is significant because of the importance of silanes as surface functionalization reagents, and in particular because of the increasing importance of gas phase silane deposition.

  12. Reaching Grid Parity Using BP Solar Crystalline Silicon Technology: A Systems Class Application

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, Daniel W; Wohlgemuth, John; Carlson, David E; Clark, Roger F; Gleaton, Mark; Posbic, John P; Zahler, James

    2010-12-06

    The primary target market for this program was the residential and commercial PV markets, drawing on BP Solar's premium product and service offerings, brand and marketing strength, and unique routes to market. These two markets were chosen because: (1) in 2005 they represented more than 50% of the overall US PV market; (2) they are the two markets that will likely meet grid parity first; and (3) they are the two market segments in which product development can lead to the added value necessary to generate market growth before reaching grid parity. Federal investment in this program resulted in substantial progress toward the DOE TPP target, providing significant advancements in the following areas: (1) Lower component costs particularly the modules and inverters. (2) Increased availability and lower cost of silicon feedstock. (3) Product specifically developed for residential and commercial applications. (4) Reducing the cost of installation through optimization of the products. (5) Increased value of electricity in mid-term to drive volume increases, via the green grid technology. (6) Large scale manufacture of PV products in the US, generating increased US employment in manufacturing and installation. To achieve these goals BP Solar assembled a team that included suppliers of critical materials, automated equipment developers/manufacturers, inverter and other BOS manufacturers, a utility company, and University research groups. The program addressed all aspects of the crystalline silicon PV business from raw materials (particularly silicon feedstock) through installation of the system on the customers site. By involving the material and equipment vendors, we ensured that supplies of silicon feedstock and other PV specific materials like encapsulation materials (EVA and cover glass) will be available in the quantities required to meet the DOE goals of 5 to 10 GW of installed US PV by 2015 and at the prices necessary for PV systems to reach grid parity in 2015

  13. Observation by conductive-probe atomic force microscopy of strongly inverted surface layers at the hydrogenated amorphous silicon/crystalline silicon heterojunctions

    Science.gov (United States)

    Maslova, O. A.; Alvarez, J.; Gushina, E. V.; Favre, W.; Gueunier-Farret, M. E.; Gudovskikh, A. S.; Ankudinov, A. V.; Terukov, E. I.; Kleider, J. P.

    2010-12-01

    Heterojunctions made of hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) are examined by conducting probe atomic force microscopy. Conductive channels at both (n )a-Si:H/(p)c-Si and (p)a-Si:H/(n)c-Si interfaces are clearly revealed. These are attributed to two-dimension electron and hole gases due to strong inversion layers at the c-Si surface in agreement with previous planar conductance measurements. The presence of a hole gas in (p )a-Si:H/(n)c-Si structures implies a quite large valence band offset (EVc-Si-EVa-Si:H>0.25 eV).

  14. High-rate deposition of nano-crystalline silicon thin films on plastics

    Energy Technology Data Exchange (ETDEWEB)

    Marins, E.; Guduru, V.; Cerqueira, F.; Alpuim, P. [Centro de Fisica, Universidade do Minho, 4800-058 Guimaraes, 4710-057 Braga (Portugal); Ribeiro, M. [Centro de Nanotecnologia e Materiais Tecnicos, Funcionais e Inteligentes (CeNTI), 4760-034 Vila Nova de Famalicao (Portugal); Bouattour, A. [Institut fuer Physikalische Elektronik (ipe), Universitaet Stuttgart, 70569 Stuttgart (Germany)

    2011-03-15

    Nanocrystalline silicon (nc-Si:H) is commonly used in the bottom cell of tandem solar cells. With an indirect bandgap, nc-Si:H requires thicker ({proportional_to}1 {mu}m) films for efficient light harvesting than amorphous Si (a-Si:H) does. Therefore, thin-film high deposition rates are crucial for further cost reduction of highly efficient a-Si:H based photovoltaic technology. Plastic substrates allow for further cost reduction by enabling roll-to-roll inline deposition. In this work, high nc-Si:H deposition rates on plastic were achieved at low substrate temperature (150 C) by standard Radio-frequency (13.56 MHz) Plasma Enhanced Chemical Vapor Deposition. Focus was on the influence of deposition pressure, inter-electrode distance (1.2 cm) and high power coupled to the plasma, on the hydrogen-to-silane dilution ratios (HD) necessary to achieve the amorphous-to-nanocrystalline phase transition and on the resulting film deposition rate. For each pressure and rf-power, there is a value of HD for which the films start to exhibit a certain amount of crystalline fraction. For constant rf-power, this value increases with pressure. Within the parameter range studied the deposition rate was highest (0.38 nm/s) for nc-Si:H films deposited at 6 Torr, 700 mW/cm{sup 2} using HD of 98.5%. Decreasing the pressure to 3 Torr (1.5 Torr) and rf-power to 350 mW/cm{sup 2} using HD - 98.5% deposition rate is 0.12 nm/s (0.076 nm/s). Raman crystalline fraction of these films is 72, 62 and 53% for the 6, 3 and 1.5 Torr films, respectively (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Crystalline silicon thin-film solar cells. Final report; Duennschicht-Solarzellen aus kristallinem Silizium. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Raeuber, A.; Wettling, W.; Eyer, A.; Faller, F.; Hebling, C.; Hurrle, A.; Lautenschlager, H.; Luedemann, R.; Lutz, F.; Reber, S.; Schetter, C.; Schillinger, N.; Schindler, R.; Schumacher, J.O.; Warta, W.

    1998-09-01

    Activities under the project covered all the processes involved in the fabrication of a crystalline silicon thin-film solar cell applying the high-temperature method, so that R and D work was carried out from testing of materials suitable for the dielectric and semiconductive layers required, development of the process sequences for fabrication of the solar cells, simulation and optimisation of the cell design through to final characterisation of the thin films and solar cells. Several cell designs were tested in parallel for intercomparison. Several high-temperature resistant materials were tested for their suitability to serve as substrate materials.The final project report presents the basic research work and studies on the physical and technological aspects of the crystalline thin-film solar cell as well as the major results of specific development work. The report shows that significant progress could be achieved. The efficiencies of all solar cell designs developed under the project are between 9 and 11%, including those using substrate materials easily available in industry, and it could be demonstrated that the solar cells are equal in potential to the wafer-based silicon cell. (orig./CB) [Deutsch] Es wurden alle wesentlichen Teilprozesse, die fuer die Entwicklung einer kristallinen Silicium Duennschicht-Solarzelle nach dem Hochtemperaturverfahren wichtig sind, bearbeitet. Der Projektrahmen reichte von der Materialentwicklung fuer die dielektrischen und halbleitenden Schichten ueber die Entwicklung der Solarzellenprozessschritte, die Simulation und Optimierung des Zellendesigns bis zur Charakterisierung von Schichten und Solarzellen. Dabei wurden mehrere verschiedene Zellentypen parallel untersucht und miteinander verglichen. In einer Studie wurden verschiedene hochtemperaturfeste Materialien auf ihre Eignung als Substrate hin untersucht. In dem hier vorgelegten Abschlussbericht werden die erarbeiteten Grundlagen zur Physik und Technologie der kristallinen

  16. Sheet resistance uniformity in drive-in step for different multi-crystalline silicon wafer dispositions

    Energy Technology Data Exchange (ETDEWEB)

    Moussi, A.; Bouhafs, D.; Mahiou, L. [Laboratoire des Cellules Photovoltaiques, Unite de Developpement de la Technologie du Silicium, 2 Bd, Frantz Fanon, B.P. 140, 7 Merveilles Alger (Algeria); Belkaid, M.S. [Dep. Electronique, Faculte de Genie Electrique et Informatique, UMMTO (Algeria)

    2009-09-15

    In this work, we present a study of emitters realized using different configurations of the silicon wafers in the quartz boat. The phosphorous liquid source is sprayed onto p-type multi-crystalline silicon substrates and the drive-in is made at high temperature in a muffle furnace. Three different configurations of the wafers in the boat are tested: separated, back to back and compact block of wafers. A fourth configuration is also used in source-receptor mode. The emitter phosphorous concentration profile is obtained by SIMS analysis. The resulting emitters are characterized by sheet resistance measurements and a comparison is made between the wafers within the same batch and from one batch to another. The uniformity and the standard deviation of the sheet resistance are calculated in each case. The emitter sheet resistance mapping of the wafer set in the middle of the boat for a given process gives a mean R{sub sq} 14.66 {omega}/sq with a standard deviation of 1.76% and uniformity of 18.7%. Standard deviations of 2.116% and 1.559% are obtained for wafers in the batch when using the spaced and compact configurations, respectively. The standard deviation is reduced to 0.68% when the wafers are used in source/receptor mode. A comparison is also made between wafers with different dilution of phosphorous source in ethanol. From these results we can conclude that the compact configuration offers better uniformity and lower standard deviation. Furthermore, when combined with the source-receptor configuration these parameters are significantly improved. This study allows the experimenter to identify the technological parameters of the solar cell emitter manufacturing and target precisely the desired values of the sheet resistance while limiting the number of rejected wafers. (author)

  17. Artificial neural systems using memristive synapses and nano-crystalline silicon thin-film transistors

    Science.gov (United States)

    Cantley, Kurtis D.

    Future computer systems will not rely solely on digital processing of inputs from well-defined data sets. They will also be required to perform various computational tasks using large sets of ill-defined information from the complex environment around them. The most efficient processor of this type of information known today is the human brain. Using a large number of primitive elements (˜1010 neurons in the neocortex) with high parallel connectivity (each neuron has ˜104 synapses), brains have the remarkable ability to recognize and classify patterns, predict outcomes, and learn from and adapt to incredibly diverse sets of problems. A reasonable goal in the push to increase processing power of electronic systems would thus be to implement artificial neural networks in hardware that are compatible with today's digital processors. This work focuses on the feasibility of utilizing non-crystalline silicon devices in neuromorphic electronics. Hydrogenated amorphous silicon (a-Si:H) nanowire transistors with Schottky barrier source/drain junctions, as well as a-Si:H/Ag resistive switches are fabricated and characterized. In the transistors, it is found that the on-current scales linearly with the effective width W eff of the channel nanowire array down to at least 20 nm. The solid-state electrolyte resistive switches (memristors) are shown to exhibit the proper current-voltage hysteresis. SPICE models of similar devices are subsequently developed to investigate their performance in neural circuits. The resulting SPICE simulations demonstrate spiking properties and synaptic learning rules that are incredibly similar to those in biology. Specifically, the neuron circuits can be designed to mimic the firing characteristics of real neurons, and Hebbian learning rules are investigated. Finally, some applications are presented, including associative learning analogous to the classical conditioning experiments originally performed by Pavlov, and frequency and pattern

  18. Advanced Front-Side Technology in Crystalline Silicon Solar Cells (Geavanceerde Frontend-Side Technolgy in kristallijn silicium zonnecellen)

    OpenAIRE

    2013-01-01

    The goal of this thesis is to improve the efficiency of silicon solar cells such that the cost/watt could be reduced to a competitive level. In this thesis, three aspects of the front-side of crystalline silicon solar cells have been investigated. Advanced texturing, emitter formation and passivation are detailed in chapters 2, 3 and 4 respectively. Below, each chapter is summarized. In chapter 2, a new technique has been developed that textures the frontside while polishing the rear-side. Th...

  19. Synthesis optimization of photonic crystals based on silicon and vanadium dioxides

    Science.gov (United States)

    Akhmadeev, A. A.; Sarandaev, E. V.; Salakhov, M. Kh

    2013-08-01

    The photonic crystal is the material which structure is characterized by periodic distribution of refraction index in the spatial directions, which have the photonic band gaps in a spectrum of own electromagnetic states. There are numerous approaches of the creation of photonic crystals. In the present the optimal conditions of synthesis of photonic crystals based on silicon dioxide as well as the inverse photonic crystals based on vanadium dioxide are investigated. It is known that the synthesis process is influenced by many different factors. We have studied the dependence of the particle size on the concentration of reagents, as well as on the duration of the reaction. These studies are important for the production of samples of photonic crystals with a definite structure.

  20. [Influence of silver/silicon dioxide on infrared absorption spectroscopy of sodium nitrate].

    Science.gov (United States)

    Yang, Shi-Ling; Yue, Li; Jia, Zhi-Jun

    2014-09-01

    Quickly detecting of ocean nutrient was one important task in marine pollution monitoring. We discovered the application of surface-enhanced infrared absorption spectroscopy in the detection of ocean nutrient through researching the evaporation of sodium nitrate solution. The silicon dioxide (SiO2) with highly dispersion was prepared by Stober method, The silver/silica (Ag/SiO2) composite materials were prepared by mixing ammonia solution and silicon dioxide aqueous solution. Three kinds of composite materials with different surface morphology were fabricated through optimizing the experimental parameter and changing the experimental process. The surface morphology, crystal orientation and surface plasmon resonance were investigated by means of the scanning electronic microscope (SEM), X-ray diffraction (XRD), UV-Visible absorption spectrum and infrared ab- sorption spectroscopy. The SEM images showed that the sample A was purified SiO2, sample B and sample C were mixture of silver nanoparticle and silicon dioxide, while sample D was completed nanoshell structure. The absorption spectroscopy showed that there was surface plasmon resonance in the UV-visible region, while there was possibility of surface plasmon resonance in the Infrared absorption region. The effect of Ag/SiO2 composite material on the infrared absorption spectra of sodium nitrite solution was investigated through systematically analyzing the infrared absorption spectroscopy of sodium nitrate solution during its evaporation, i. e. the peak integration area of nitrate and the peak integration area of water molecule. The experimental results show that the integration area of nitrate was enhanced greatly during the evaporation process while the integration area of water molecule decreased continuously. The integration area of nitrate comes from the anti-symmetric stretch vibration and the enhancement of the vibration is attributed to the interface effect of Ag/SiO2 which is consistent with Jensen T

  1. Impact of dopant concentrations on emitter formation with spin on dopant source in n-type crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Singha, Bandana; Solanki, Chetan Singh [Department of Energy Science and Technology, Indian Institute of Technology, Bombay Mumbai-400076, Maharashtra (India)

    2016-05-06

    Use of a suitable dopant source for emitter formation is an essential requirement in n-type crystalline silicon solar cells. Boron spin on dopant source, used as alternative to mostly used BBr{sub 3} liquid source, can yield an emitter with less diffusion induced defects under controlled conditions. Different concentrations of commercially available spin on dopant source is used and optimized in this work for sheet resistance values of the emitter ranging from 30 Ω/□ to 70 Ω/□ with emitter doping concentrations suitable for ohmic contacts. The dopant concentrations diluted with different ratios improves the carrier lifetime and thus improves the emitter performance. Hence use of suitable dopant source is essential in forming emitters in n-type crystalline silicon solar cells.

  2. Large-size, high-uniformity, random silver nanowire networks as transparent electrodes for crystalline silicon wafer solar cells.

    Science.gov (United States)

    Xie, Shouyi; Ouyang, Zi; Jia, Baohua; Gu, Min

    2013-05-06

    Metal nanowire networks are emerging as next generation transparent electrodes for photovoltaic devices. We demonstrate the application of random silver nanowire networks as the top electrode on crystalline silicon wafer solar cells. The dependence of transmittance and sheet resistance on the surface coverage is measured. Superior optical and electrical properties are observed due to the large-size, highly-uniform nature of these networks. When applying the nanowire networks on the solar cells with an optimized two-step annealing process, we achieved as large as 19% enhancement on the energy conversion efficiency. The detailed analysis reveals that the enhancement is mainly caused by the improved electrical properties of the solar cells due to the silver nanowire networks. Our result reveals that this technology is a promising alternative transparent electrode technology for crystalline silicon wafer solar cells.

  3. Evaluation of defects generation in crystalline silicon ingot grown by cast technique with seed crystal for solar cells.

    Science.gov (United States)

    Tachibana, Tomihisa; Sameshima, Takashi; Kojima, Takuto; Arafune, Koji; Kakimoto, Koichi; Miyamura, Yoshiji; Harada, Hirofumi; Sekiguchi, Takashi; Ohshita, Yoshio; Ogura, Atsushi

    2012-04-01

    Although crystalline silicon is widely used as substrate material for solar cell, many defects occur during crystal growth. In this study, the generation of crystalline defects in silicon substrates was evaluated. The distributions of small-angle grain boundaries were observed in substrates sliced parallel to the growth direction. Many precipitates consisting of light elemental impurities and small-angle grain boundaries were confirmed to propagate. The precipitates mainly consisted of Si, C, and N atoms. The small-angle grain boundaries were distributed after the precipitation density increased. Then, precipitates appeared at the small-angle grain boundaries. We consider that the origin of the small-angle grain boundaries was lattice mismatch and/or strain caused by the high-density precipitation.

  4. Simplified module assembly using back-contact crystalline-silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gee, J.M.; Garrett, S.E.; Morgan, W.P.

    1997-11-01

    The authors are developing new module concepts that encapsulate and electrically connect all the crystalline-silicon (c-Si) photovoltaic (PV) cells in a module in a single step. The new assembly process (1) uses back-contact c-Si cells, (2) uses a module backplane that has both the electrical circuit, encapsulant, and backsheet in a single piece, and (3) uses a single-step process for assembly of these components into a module. This new process reduces module assembly cost by using planar processes that are easy to automate, by reducing the number of steps, and by eliminating low-throughput (e.g., individual cell tabbing, cell stringing, etc.) steps. The authors refer to this process as monolithic module assembly since it translates many of the advantages of monolithic module construction of thin-film PV modules to wafered c-Si PV modules. Preliminary development of the new module assembly process, and some estimations of the cost potential of the new process, are presented.

  5. Camera-Based Lock-in and Heterodyne Carrierographic Photoluminescence Imaging of Crystalline Silicon Wafers

    Science.gov (United States)

    Sun, Q. M.; Melnikov, A.; Mandelis, A.

    2015-06-01

    Carrierographic (spectrally gated photoluminescence) imaging of a crystalline silicon wafer using an InGaAs camera and two spread super-bandgap illumination laser beams is introduced in both low-frequency lock-in and high-frequency heterodyne modes. Lock-in carrierographic images of the wafer up to 400 Hz modulation frequency are presented. To overcome the frame rate and exposure time limitations of the camera, a heterodyne method is employed for high-frequency carrierographic imaging which results in high-resolution near-subsurface information. The feasibility of the method is guaranteed by the typical superlinearity behavior of photoluminescence, which allows one to construct a slow enough beat frequency component from nonlinear mixing of two high frequencies. Intensity-scan measurements were carried out with a conventional single-element InGaAs detector photocarrier radiometry system, and the nonlinearity exponent of the wafer was found to be around 1.7. Heterodyne images of the wafer up to 4 kHz have been obtained and qualitatively analyzed. With the help of the complementary lock-in and heterodyne modes, camera-based carrierographic imaging in a wide frequency range has been realized for fundamental research and industrial applications toward in-line nondestructive testing of semiconductor materials and devices.

  6. Organic-inorganic halide perovskite/crystalline silicon four-terminal tandem solar cells.

    Science.gov (United States)

    Löper, Philipp; Moon, Soo-Jin; de Nicolas, Sílvia Martín; Niesen, Bjoern; Ledinsky, Martin; Nicolay, Sylvain; Bailat, Julien; Yum, Jun-Ho; De Wolf, Stefaan; Ballif, Christophe

    2015-01-21

    Tandem solar cells constructed from a crystalline silicon (c-Si) bottom cell and a low-cost top cell offer a promising way to ensure long-term price reductions of photovoltaic modules. We present a four-terminal tandem solar cell consisting of a methyl ammonium lead triiodide (CH3NH3PbI3) top cell and a c-Si heterojunction bottom cell. The CH3NH3PbI3 top cell exhibits broad-band transparency owing to its design free of metallic components and yields a transmittance of >55% in the near-infrared spectral region. This allows the generation of a short-circuit current density of 13.7 mA cm(-2) in the bottom cell. The four-terminal tandem solar cell yields an efficiency of 13.4% (top cell: 6.2%, bottom cell: 7.2%), which is a gain of 1.8%abs with respect to the reference single-junction CH3NH3PbI3 solar cell with metal back contact. We employ the four-terminal tandem solar cell for a detailed investigation of the optical losses and to derive guidelines for further efficiency improvements. Based on a power loss analysis, we estimate that tandem efficiencies of ∼28% are attainable using an optically optimized system based on current technology, whereas a fully optimized, ultimate device with matched current could yield up to 31.6%.

  7. Effects of photon reabsorption phenomena in confocal micro-photoluminescence measurements in crystalline silicon

    Science.gov (United States)

    Roigé, A.; Alvarez, J.; Jaffré, A.; Desrues, T.; Muñoz, D.; Martín, I.; Alcubilla, R.; Kleider, J.-P.

    2017-02-01

    Confocal micro-photoluminescence (PL) spectroscopy has become a powerful characterization technique for studying novel photovoltaic (PV) materials and structures at the micrometer level. In this work, we present a comprehensive study about the effects and implications of photon reabsorption phenomena on confocal micro-PL measurements in crystalline silicon (c-Si), the workhorse material of the PV industry. First, supported by theoretical calculations, we show that the level of reabsorption is intrinsically linked to the selected experimental parameters, i.e., focusing lens, pinhole aperture, and excitation wavelength, as they define the spatial extension of the confocal detection volume, and therefore, the effective photon traveling distance before collection. Second, we also show that certain sample properties such as the reflectance and/or the surface recombination velocity can also have a relevant impact on reabsorption. Due to the direct relationship between the reabsorption level and the spectral line shape of the resulting PL emission signal, reabsorption phenomena play a paramount role in certain types of micro-PL measurements. This is demonstrated by means of two practical and current examples studied using confocal PL, namely, the estimation of doping densities in c-Si and the study of back-surface and/or back-contacted Si devices such as interdigitated back contact solar cells, where reabsorption processes should be taken into account for the proper interpretation and quantification of the obtained PL data.

  8. A Low Resistance Calcium/Reduced Titania Passivated Contact for High Efficiency Crystalline Silicon Solar Cells

    KAUST Repository

    Allen, Thomas G.

    2017-02-04

    Recent advances in the efficiency of crystalline silicon (c-Si) solar cells have come through the implementation of passivated contacts that simultaneously reduce recombination and resistive losses within the contact structure. In this contribution, low resistivity passivated contacts are demonstrated based on reduced titania (TiOx) contacted with the low work function metal, calcium (Ca). By using Ca as the overlying metal in the contact structure we are able to achieve a reduction in the contact resistivity of TiOx passivated contacts of up to two orders of magnitude compared to previously reported data on Al/TiOx contacts, allowing for the application of the Ca/TiOx contact to n-type c-Si solar cells with partial rear contacts. Implementing this contact structure on the cell level results in a power conversion efficiency of 21.8% where the Ca/TiOx contact comprises only ≈6% of the rear surface of the solar cell, an increase of 1.5% absolute compared to a similar device fabricated without the TiOx interlayer.

  9. Optimization of textured-dielectric coatings for crystalline-silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gee, J.M. [Sandia National Labs., Albuquerque, NM (United States). Photovoltaic System Components Dept.; Gordon, R.; Liang, H. [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry

    1996-07-01

    The authors report on the optimization of textured-dielectric coatings for reflectance control in crystalline-silicon (c-Si) photovoltaic modules. Textured-dielectric coatings reduce encapsulated-cell reflectance by promoting optical confinement in the module encapsulation; i.e., the textured-dielectric coating randomizes the direction of rays reflected from the dielectric and from the c-Si cell so that many of these reflected rays experience total internal reflection at the glass-air interface. Some important results of this work include the following: the authors demonstrated textured-dielectric coatings (ZnO) deposited by a high-throughput low-cost deposition process; they identified factors important for achieving necessary texture dimensions; they achieved solar-weighted extrinsic reflectances as low as 6% for encapsulated c-Si wafers with optimized textured-ZnO coatings; and they demonstrated improvements in encapsulated cell performance of up to 0.5% absolute compared to encapsulated planar cells with single-layer antireflection coatings.

  10. Memory effect in MOS structures containing amorphous or crystalline silicon nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Sebastian; Brueggemann, Rudolf; Bauer, Gottfried Heinrich [Institute of Physics, Carl von Ossietzky University Oldenburg, D-26111 Oldenburg (Germany); Nedev, Nicola [Istituto de Ingenieria, Universidad Autonoma de Baja California, Benito Juarez Blvd., s/n, C.P. 21280, Mexicali, Baja California (Mexico); Manolov, Emmo; Nesheva, Diana; Levi, Zelma [Insitute of Solid State Physics, Bulgarian Academy of Science, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria)

    2008-07-01

    Amorphous and crystalline silicon nanoparticles (Si-NPs) embedded in a SiO{sub 2} matrix are fabricated by thermal annealing of Metal/SiO{sub 2}/SiO{sub x}/c-Si structures (x=1.15) at 700 C or 1000 C in N{sub 2} atmosphere for 30 or 60 minutes. High frequency C-V measurements show that the samples can be charged negatively or positively by applying a positive or negative bias voltage to the gate. A memory effect, due to the Si-NPs in the SiO{sub 2} matrix, is observed. The method of measurement with open circuit between two measurements leads to the retention characteristic where the structures retain about 50% of negative charge trapped in Si-NPs for 24 hours. A second method, where the flat-band voltage is applied as bias voltage, shows shorter retention characteristics. There the Si-NPs retain 50% of their charge after 10 hours.

  11. Characterization of cell mismatch in a multi-crystalline silicon photovoltaic module

    Energy Technology Data Exchange (ETDEWEB)

    Crozier, J.L., E-mail: s207094248@live.nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Dyk, E.E. van; Vorster, F.J. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    In this study the causes and effects of cell mismatch were identified in a multi-crystalline silicon photovoltaic module. Different techniques were used to identify the causes of the mismatch, including Electroluminescence (EL) imaging, Infrared (IR) imaging, current-voltage (I-V) characteristics, worst-case cell determination and Large Area Laser Beam Induced Current (LA-LBIC) scans. In EL images the cracked cells, broken fingers and material defects are visible. The presence of poorly contacted cells results in the formation of hot-spots. LA-LBIC line scans give the relative photoresponse of the cells in the module. However, this technique is limited due to the penetration depth of the laser beam. The worst case cell determination compares the I-V curves of the whole module with the I-V curve of the module with one cell covered, allowing the evaluation of the performance of each cell in a series-connected string. These methods allowed detection of the poorly performing cells in the module. Using all these techniques an overall view of the photoresponse in the cells and their performance is obtained.

  12. Formation of nanostructures from colloidal solutions of silicon dioxide and carbon nanotubes

    Science.gov (United States)

    Zhukalin, D. A.; Tuchin, A. V.; Goloshchapov, D. L.; Bityutskaya, L. A.

    2015-02-01

    The formation of nanostructures from colloidal solutions of amorphous silicon dioxide (SiO2) and carbon nanotubes (CNTs) in evaporating drops at room temperature has been studied. It is established that spherical aggregates with an average diameter of ˜2 μm and rodlike nanostructures with diameters within 250-300 nm and lengths of ˜4 μm are formed under these conditions. The mechanisms of covalent and van der Waals interaction between CNTs and SiO2 are considered in the framework of a phenomenological model of the active center of a closed CNT.

  13. Ultra-thin crystalline silicon films produced by plasma assisted epitaxial growth on silicon wafers and their transfer to foreign substrates*

    Directory of Open Access Journals (Sweden)

    Cabarrocas P. Roca i

    2010-10-01

    Full Text Available We have developed a new process to produce ultra-thin crystalline silicon films with thicknesses in the range of 0.1 − 1 μm on flexible substrates. A crystalline silicon wafer was cleaned by SiF4 plasma exposure and without breaking vacuum, an epitaxial film was grown from SiF4, H2 and Ar gas mixtures at low substrate temperature (Tsub ≈ 200 °C in a standard RF PECVD reactor. We found that H2 dilution is a key parameter for the growth of high quality epitaxial films and modification of the structural composition of the interface with the c-Si wafer, allowing one to switch from a smooth interface at low hydrogen flow rates to a fragile one, composed of hydrogen-rich micro-cavities, at high hydrogen flow rates. This feature can be advantageously used to separate the epitaxial film from the crystalline Si wafer. As a example demonstration, we show that by depositing a metal film followed by a spin-coated polyimide layer and applying a moderate thermal treatment to the stack, the fragile interface breaks down and allows one to obtain an ultrathin crystalline wafer on the flexible polyimide support.

  14. Defects and defect generation in oxide layer of ion implanted silicon-silicon dioxide structures

    CERN Document Server

    Baraban, A P

    2002-01-01

    One studies mechanism of generation of defects in Si-SiO sub 2 structure oxide layer as a result of implantation of argon ions with 130 keV energy and 10 sup 1 sup 3 - 3.2 x 10 sup 1 sup 7 cm sup - sup 2 doses. Si-SiO sub 2 structures are produced by thermal oxidation of silicon under 950 deg C temperature. Investigations were based on electroluminescence technique and on measuring of high-frequency volt-farad characteristics. Increase of implantation dose was determined to result in spreading of luminosity centres and in its maximum shifting closer to boundary with silicon. Ion implantation was shown, as well, to result in increase of density of surface states at Si-SiO sub 2 interface. One proposed model of defect generation resulting from Ar ion implantation into Si-SiO sub 2

  15. Silicon-Based Multiple Microsensors for Sensing Carbon Dioxide, Humidity and Temperature.

    Science.gov (United States)

    Chang, Hsing-Cheng

    A silicon based multiple microsensor for sensing carbon dioxide, humidity and temperature has been investigated. The carbon dioxide microsensor was designed based on gas permeable membrane and ion-sensing field effect transistor structures. The humidity microsensor was designed based on metal-oxide -semiconductor transistor with a polyimide sensing film. The temperature microsensor was also designed based on diode -sensing structure. The multiple microsensors were designed on the same chip and were fabricated by using standard VLSI processing techniques, micromachining processes and compatible polyimide processes. Small dimension, room temperature operation, fast response, and a relatively large chemical reservoir with an inner temperature controlled resistor are some of the special characteristics of this microsensor. Polyimides PMDA-ODA and 6FDA-ODA were chosen for humidity sensing, CO_2 gas selection and for wafer bonding. The polyimide and solid state compatible processes have been developed to reduce the sensor's dimension, simplify the fabrication process, and lower the production cost. A gaseous CO_2 measurement system was developed for measuring the device characteristics. The reaction parameters of the sensors have been analyzed and discussed to explain their sensing mechanisms. A novel polyimide assisted silicon wafer bonding method was investigated. The polyimide PI-2566 (6FDA-ODA) and the adhesion promoter VM-651 (aminopropyltriethoxysilane) were used as an intermediate material to bond two silicon wafers together. By sawing the bonded wafer and measuring the bond strength it was found that this method gave a uniform and strong bond. The bonding temperature was varied from 235^circC to 400 ^circC and the bond absorption characteristics were identified by analyzing the FTIR spectra. The bonding results are discussed and a bond model for the polyimide assisted silicon wafer bonding is suggested. This bonding process is simple and the yield rate is very

  16. Numerical modelling on stress and dislocation generation in multi-crystalline silicon during directional solidification for PV applications

    Science.gov (United States)

    Srinivasan, M.; Karuppasamy, P.; Ramasamy, P.; Barua, A. K.

    2016-07-01

    Numerical modelling has emerged as a powerful tool for the development and optimization of directional solidification process for mass production of multicrystalline silicon. A transient global heat transfer model is performed to investigate the effect of bottom grooved furnace upon the directional solidification (DS) process of multi-crystalline silicon (mc-Si). The temperature distribution, von Mises stress, residual stress and dislocation density rate in multi-crystalline silicon ingots grown by modified directional solidification method have been investigated for five growth stages using finite volume method at the critical Prandtl number, Pr = 0.01. This paper discusses bottom groove furnace instead of seed crystal DS method. It achieves an advanced understanding of the thermal and mechanical behaviour in grown multi-crystalline ingot by bottom grooved directional solidification method. The von Mises stress and dislocation density were reduced while using the bottom grooved furnace. This work was carried out in the different grooves of radius 30 mm, 60 mm and 90 mm of the heat exchanger block of the DS furnace. In this paper, the results are presented for 60 mm radius groove only because it has got better results compared to the other grooves. Also, the computational results of bottom grooved DS method show better performance compared the conventional DS method for stress and dislocation density in grown ingot. [Figure not available: see fulltext.

  17. Chemical Analysis Method for Magnesia and Magnesia-Alumina Refractories——Gravimetric-Molybdenum Blue Photometric Method for Determination of Silicon Dioxide Content

    Institute of Scientific and Technical Information of China (English)

    Wang Jing

    2007-01-01

    @@ GB/T 5069.3 - 2001 1 Scope This standard specifies the gravimetric-molybdenum blue photometric method for determination of silicon dioxide content. This standard is used for the determination of silicon dioxide content of magnesia and magnesia-alumina refractory materials. Determination range: >5.00%.

  18. High-Temperature Permittivity and Data-Mining of Silicon Dioxide at GHz Band

    Institute of Scientific and Technical Information of China (English)

    YUAN Jie; WEN Bo; HOU Zhi-Ling; LU Ming-Ming; CAO Wen-Qiang; BA Chuan; FANG Xiao-Yong; CAO Mao-Sheng

    2012-01-01

    The high-temperature permittivity of quartz fibre-reinforced silicon dioxide (SiO2/SiO2 ) nano-composites is studied on the basis of the multi-scale theoretical model.We obtain the permittivity of the SiO2/SiO2 at high temperature,which is dependent on the temperature by data-mining.The result shows that the permittivity and loss tangent obtained by data-mining are well consistent with the measured ones.The high-temperature permittivity can be well predicted for SiO2/SiO2 by the as-proposed model and the data-mining method.%The high-temperature permittivity of quartz fibre-reinforced silicon dioxide (SiO2/SiO2) nano-composites is studied on the basis of the multi-scale theoretical model. We obtain the permittivity of the SiO2/SiO2 at high temperature, which is dependent on the temperature by data-mining. The resuJt shows that the permittivity and loss tangent obtained by data-mining are well consistent with the measured ones. The high-temperature permittivity can be well predicted for SiO2/SiO2 by the as-proposed model and the data-mining method.

  19. Light transmission in porous silicon dioxide filled with liquids of different refractive indices

    Institute of Scientific and Technical Information of China (English)

    Jun Li; Xinzheng Zhang; Fan Shi; Yan Xu; Pidong Wang; Xuanyi Yu; Jingjun Xu

    2011-01-01

    Optical transmission at 532 nm from nonabsorbing disordered porous silicon dioxide has been studied experimentally.The transmission behaviors can be adjusted by filling the pores with liquids of different refractive indics, which are analyzed based on the theory of diffusion in a weak scattering regime.In our experiment, the transmission coefficient changes from a value less than 1% to one that is greater than 75%, that is, the opaque sample becomes transparent, which means that the transport mean free path of light within the material has been effectively adjusted.In addition, this method is a useful nondestructive method to derive the refractive index of an unknown bulk porous material.%@@ Optical transmission at 532 nm from nonabsorbing disordered porous silicon dioxide has been studied experimentally.The transmission behaviors can be adjusted by filling the pores with liquids of different refractive indics, which are analyzed based on the theory of diffusion in a weak scattering regime.In our experiment, the transmission coefficient changes from a value less than 1% to one that is greater than 75%, that is, the opaque sample becomes transparent, which means that the transport mean free path of light within the material has been effectively adjusted.In addition, this method is a useful nondestructive method to derive the refractive index of an unknown bulk porous material.

  20. Modification of Shape Memory Polymer Foams Using Tungsten, Aluminum Oxide, and Silicon Dioxide Nanoparticles.

    Science.gov (United States)

    Hasan, S M; Thompson, R S; Emery, H; Nathan, A L; Weems, A C; Zhou, F; Monroe, M B B; Maitland, D J

    Shape memory polymer (SMP) foams were synthesized with three different nanoparticles (tungsten, silicon dioxide, and aluminum oxide) for embolization of cerebral aneurysms. Ultra-low density SMP foams have previously been utilized for aneurysm occlusion, resulting in a rapid, stable thrombus. However, the small cross section of foam struts can potentially lead to fracture and particulate generation, which would be a serious adverse event for an embolic device. The goal of this study was to improve the mechanical properties of the system by physically incorporating fillers into the SMP matrix. Thermal and mechanical characterization suggested minimal changes in thermal transition of the SMP nanocomposites and improved mechanical strength and toughness for systems with low filler content. Actuation profiles of the three polymer systems were tuned with filler type and content, resulting in faster SMP foam actuation for nanocomposites containing higher filler content. Additionally, thermal stability of the SMP nanocomposites improved with increasing filler concentration, and particulate count remained well below accepted standard limits for all systems. Extraction studies demonstrated little release of silicon dioxide and aluminum oxide from the bulk over 16 days. Tungstun release increased over the 16 day examination period, with a maximum measured concentration of approxiately 2.87 μg/mL. The SMP nanocomposites developed through this research have the potential for use in medical devices due to their tailorable mechanical properties, thermal resisitivity, and actuation profiles.

  1. Characteristics of a-plane GaN films grown on optimized silicon-dioxide-patterned r-plane sapphire substrates

    Energy Technology Data Exchange (ETDEWEB)

    Son, Ji-Su, E-mail: sonjisu@gmail.com [Department of Electrical Engineering and Computer Science, Nagoya University, C3-1 Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Akasaki Research Center, Nagoya University, C3-1 Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Honda, Yoshio; Yamaguchi, Masahito; Amano, Hiroshi [Department of Electrical Engineering and Computer Science, Nagoya University, C3-1 Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Akasaki Research Center, Nagoya University, C3-1 Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Baik, Kwang Hyeon [Department of Materials Science and Engineering, Hongik University, Jochiwon, Chungnam 339-701 (Korea, Republic of); Seo, Yong Gon; Hwang, Sung-Min [Optoelectronics Laboratory, Korea Electronics Technology Institute, Gyeonggi-do 463-816 (Korea, Republic of)

    2013-11-01

    We report on the characteristics of a-plane GaN films directly grown on optimized silicon-dioxide-patterned r-plane sapphire substrates. Various shapes and sizes of silicon dioxide patterns were considered with the aim of achieving fully coalescent a-plane GaN films with a smooth surface and high crystalline quality. The omega full widths at half maximum of the (11–20) X-ray rocking curve values of optimized a-plane GaN films with regular hexagonal patterns of 1 μm window width and 6 μm mask width were measured to be 597 arc sec along the c-axis direction and 457 arc sec along the m-axis direction. Atomic force microscopy images revealed a significant reduction in the density of submicron pits in the mask region. Plan-view and cross-sectional transmission electron microscopy images showed that basal stacking faults and threading dislocation densities were reduced from ∼ 5.7 × 10{sup 5} cm{sup −1} and ∼ 1 × 10{sup 9} cm{sup −2} in the window region to ∼ 1.8 × 10{sup 5} cm{sup −1} and ∼ 2.1 × 10{sup 8} cm{sup −2} in the mask region, respectively. - Highlights: • Optimal hexagonal patterns (OHP) with 1 μm window width and 6 μm mask width. • Fully coalescent α-plane GaN with smooth surface and high crystalline quality. • Decreased anisotropy and defect density in α-plane GaN with SiO{sub 2} OHP.

  2. Synthesis of silicon carbide-silicon nitride composite ultrafine particles using a carbon dioxide laser

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Masaaki; Maniette, Yves; Nakata, Yoshinori; Okutani, Takeshi (Government Industrial Development Lab., Hokkaido, Sapporo (Japan))

    1993-05-01

    The synthesis and the structure of silicon carbide-silicon nitride (SiC-Si[sub 3]N[sub 4]) composite ultrafine particles have been studied. SiC-Si[sub 3]N[sub 4] composite ultrafine particles were prepared by irradiating a SiH[sub 4], C[sub 2]H[sub 4], and NH[sub 3] gas mixture with a CO[sub 2] laser at atmospheric pressure. The composition of composite powders changed with the reactant gas flow rate. The carbon and nitrogen content of the powder could be controlled in a wide range from 0 to 30 wt%. The composite powder, which contained 25.3 wt% carbon and 5.8 wt% nitrogen, had a [beta]-SiC structure. As the nitrogen content increased, SiC decreased and amorphous phase, Si[sub 3]N[sub 4], Si appeared. The results of XPS and lattice constant measurements suggested that Si, C, and N atoms were intimately mixed in the composite particles.

  3. Supercritical Carbon Dioxide-Assisted Process for Well-Dispersed Silicon/Graphene Composite as a Li ion Battery Anode

    OpenAIRE

    2016-01-01

    The silicon (Si)/graphene composite has been touted as one of the most promising anode materials for lithium ion batteries. However, the optimal fabrication method for this composite remains a challenge. Here, we developed a novel method using supercritical carbon dioxide (scCO2) to intercalate Si nanoparticles into graphene nanosheets. Silicon was modified with a thin layer of polyaniline, which assisted the dispersion of graphene sheets by introducing π-π interaction. Using scCO2, well-disp...

  4. Thermal oxidation of silicon in a residual oxygen atmosphere—the RESOX process—for self-limiting growth of thin silicon dioxide films

    Science.gov (United States)

    Wright, Jason T.; Carbaugh, Daniel J.; Haggerty, Morgan E.; Richard, Andrea L.; Ingram, David C.; Kaya, Savas; Jadwisienczak, Wojciech M.; Rahman, Faiz

    2016-10-01

    We describe in detail the growth procedures and properties of thermal silicon dioxide grown in a limited and dilute oxygen atmosphere. Thin thermal oxide films have become increasingly important in recent years due to the continuing down-scaling of ultra large scale integration metal oxide silicon field effect transistors. Such films are also of importance for organic transistors where back-gating is needed. The technique described here is novel and allows self-limited formation of high quality thin oxide films on silicon surfaces. This technique is easy to implement in both research laboratory and industrial settings. Growth conditions and their effects on film growth have been described. Properties of the resulting oxide films, relevant for microelectronic device applications, have also been investigated and reported here. Overall, our findings are that thin, high quality, dense silicon dioxide films of thicknesses up to 100 nm can be easily grown in a depleted oxygen environment at temperatures similar to that used for usual silicon dioxide thermal growth in flowing dry oxygen.

  5. Enhancing crystalline silicon solar cell efficiency with SixGe1-x layers

    Science.gov (United States)

    Ali, Adnan; Cheow, S. L.; Azhari, A. W.; Sopian, K.; Zaidi, Saleem H.

    Crystalline silicon (c-Si) solar cell represents a cost effective, environment-friendly, and proven renewable energy resource. Industrially manufacturing of c-Si solar has now matured in terms of efficiency and cost. Continuing cost-effective efficiency enhancement requires transition towards thinner wafers in near term and thin-films in the long term. Successful implementation of either of these alternatives must address intrinsic optical absorption limitation of Si. Bandgap engineering through integration with SixGe1-x layers offers an attractive, inexpensive option. With the help of PC1D software, role of SixGe1-x layers in conventional c-Si solar cells has been intensively investigated in both wafer and thin film configurations by varying Ge concentration, thickness, and placement. In wafer configuration, increase in Ge concentration leads to enhanced absorption through bandgap broadening with an efficiency enhancement of 8% for Ge concentrations of less than 20%. At higher Ge concentrations, despite enhanced optical absorption, efficiency is reduced due to substantial lowering of open-circuit voltage. In 5-25-μm thickness, thin-film solar cell configurations, efficiency gain in excess of 30% is achievable. Therefore, SixGe1-x based thin-film solar cells with an order of magnitude reduction in costly Si material are ideally-suited both in terms of high efficiency and cost. Recent research has demonstrated significant improvement in epitaxially grown SixGe1-x layers on nanostructured Si substrates, thereby enhancing potential of this approach for next generation of c-Si based photovoltaics.

  6. Femtosecond laser-controlled self-assembly of amorphous-crystalline nanogratings in silicon

    Science.gov (United States)

    Puerto, Daniel; Garcia-Lechuga, Mario; Hernandez-Rueda, Javier; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan

    2016-07-01

    Self-assembly (SA) of molecular units to form regular, periodic extended structures is a powerful bottom-up technique for nanopatterning, inspired by nature. SA can be triggered in all classes of solid materials, for instance, by femtosecond laser pulses leading to the formation of laser-induced periodic surface structures (LIPSS) with a period slightly shorter than the laser wavelength. This approach, though, typically involves considerable material ablation, which leads to an unwanted increase of the surface roughness. We present a new strategy to fabricate high-precision nanograting structures in silicon, consisting of alternating amorphous and crystalline lines, with almost no material removal. The strategy can be applied to static irradiation experiments and can be extended into one and two dimensions by scanning the laser beam over the sample surface. We demonstrate that lines and areas with parallel nanofringe patterns can be written by an adequate choice of spot size, repetition rate and scan velocity, keeping a constant effective pulse number (N eff) per area for a given laser wavelength. A deviation from this pulse number leads either to inhomogeneous or ablative structures. Furthermore, we demonstrate that this approach can be used with different laser systems having widely different wavelengths (1030 nm, 800 nm, 400 nm), pulse durations (370 fs, 100 fs) and repetition rates (500 kHz, 100 Hz, single pulse) and that the grating period can also be tuned by changing the angle of laser beam incidence. The grating structures can be erased by irradiation with a single nanosecond laser pulse, triggering recrystallization of the amorphous stripes. Given the large differences in electrical conductivity between the two phases, our structures could find new applications in nanoelectronics.

  7. Synthesis of Crystalline Nanosized Titanium Dioxide via a Reverse Micelle Method at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Crystalline TiO2 nanoparticles were synthesized by hydrolysis of titanium tetrabutoxidein the presence of hydrochloric aeid in NP-5 (lgepal CO-520)/ cyclohcxane reverse micellesolution at room temperature. Pure rutilc nanoparticles were obtained at an appropriate acidconcentration. The influcnces of various reaction conditions such as the concentration of acids,water content value (w=[H2O]/[NP-5]) on the formation, crystal phase, morphology, and size of theTiO2 particles were investigated.

  8. [Effects of silver and silicon dioxide nanopowders on the development of herpesvirus infection in vitro].

    Science.gov (United States)

    Sopova, E A; Baranov, V I; Gankovskaia, O A; Lavrov, V F; Zverev, V V

    2010-01-01

    Estimation of the potential ability of nanoparticles (NP) to affect human health has generated a need for developing rapid, sensitive, and efficient laboratory tests of the toxicity of nanomaterials. The purpose of the investigation was to study the cytotoxic effect of NP of silver (Ag) and silicon dioxide (SiO2). The transplantable Vero cells treated with NP at different concentrations were used as target cells. Some experiments examined the combined effects of nanopowders and herpes simplex virus type 2 (HSV-2) on Vero cell viability and the direct effect of NP on the reproductive potential of HSV-2 in the culture. SiO2 NPs at concentrations of 1.0 to 0.1 mg/ml were found to cause a marked cytotoxic effect that was in the complete destruction of the cell monolayer. Ag HPs were more toxic than silicon nanopowders and induced a complete degradation of the cell monolayer at substantially lower concentrations. The results of the study formed the basis for the development of a rapid (24-48-hour), reliable, and efficient test for the toxicity of nanomaterials, by using the cultured cells in the laboratory setting. It was also shown that silicon NPs did not noticeably affect the reproductive potential of HSV-2 while nano silver suppressed the capacity of HSV-2 for multiplication, by significantly reducing viral progeny titer in the cell culture.

  9. Crystallization of silicon dioxide and compositional evolution of the Earth's core.

    Science.gov (United States)

    Hirose, Kei; Morard, Guillaume; Sinmyo, Ryosuke; Umemoto, Koichio; Hernlund, John; Helffrich, George; Labrosse, Stéphane

    2017-03-02

    The Earth's core is about ten per cent less dense than pure iron (Fe), suggesting that it contains light elements as well as iron. Modelling of core formation at high pressure (around 40-60 gigapascals) and high temperature (about 3,500 kelvin) in a deep magma ocean predicts that both silicon (Si) and oxygen (O) are among the impurities in the liquid outer core. However, only the binary systems Fe-Si and Fe-O have been studied in detail at high pressures, and little is known about the compositional evolution of the Fe-Si-O ternary alloy under core conditions. Here we performed melting experiments on liquid Fe-Si-O alloy at core pressures in a laser-heated diamond-anvil cell. Our results demonstrate that the liquidus field of silicon dioxide (SiO2) is unexpectedly wide at the iron-rich portion of the Fe-Si-O ternary, such that an initial Fe-Si-O core crystallizes SiO2 as it cools. If crystallization proceeds on top of the core, the buoyancy released should have been more than sufficient to power core convection and a dynamo, in spite of high thermal conductivity, from as early on as the Hadean eon. SiO2 saturation also sets limits on silicon and oxygen concentrations in the present-day outer core.

  10. Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface-Interface Composition and the Framework Crystallinity.

    Science.gov (United States)

    Milowska, Katarzyna; Rybczyńska, Aneta; Mosiolek, Joanna; Durdyn, Joanna; Szewczyk, Eligia M; Katir, Nadia; Brahmi, Younes; Majoral, Jean-Pierre; Bousmina, Mosto; Bryszewska, Maria; El Kadib, Abdelkrim

    2015-09-16

    Hitherto, the field of nanomedicine has been overwhelmingly dominated by the use of mesoporous organosilicas compared to their metal oxide congeners. Despite their remarkable reactivity, titanium oxide-based materials have been seldom evaluated and little knowledge has been gained with respect to their "structure-biological activity" relationship. Herein, a fruitful association of phosphorus dendrimers (both "ammonium-terminated" and "phosphonate-terminated") and titanium dioxide has been performed by means of the sol-gel process, resulting in mesoporous dendrimer-coated nanosized crystalline titanium dioxide. A similar organo-coating has been reproduced using single branch-mimicking dendrimers that allow isolation of an amorphous titanium dioxide. The impact of these materials on red blood cells was evaluated by studying cell hemolysis. Next, their cytotoxicity toward B14 Chinese fibroblasts and their antimicrobial activity were also investigated. Based on their variants (cationic versus anionic terminal groups and amorphous versus crystalline titanium dioxide phase), better understanding of the role of the surface-interface composition and the nature of the framework has been gained. No noticeable discrimination was observed for amorphous and crystalline material. In contrast, hemolysis and cytotoxicity were found to be sensitive to the nature of the interface composition, with the ammonium-terminated dendrimer-coated titanium dioxide being the most hemolytic and cytotoxic material. This surface-functionalization opens the door for creating a new synergistic machineries mechanism at the cellular level and seems promising for tailoring the biological activity of nanosized organic-inorganic hybrid materials.

  11. Scanning transmission electron microscope analysis of amorphous-Si insertion layers prepared by catalytic chemical vapor deposition, causing low surface recombination velocities on crystalline silicon wafers

    OpenAIRE

    2012-01-01

    Microstructures of stacked silicon-nitride/amorphous-silicon/crystalline-silicon (SiN_x/a-Si/c-Si) layers prepared by catalytic chemical vapor deposition were investigated with scanning transmission electron microscopy to clarify the origin of the sensitive dependence of surface recombination velocities (SRVs) of the stacked structure on the thickness of the a-Si layer. Stacked structures with a-Si layers with thicknesses greater than 10 nm exhibit long effective carrier lifetimes, while thos...

  12. The effect of metallic coatings and crystallinity on the volume expansion of silicon during electrochemical lithiation/delithiation

    KAUST Repository

    McDowell, Matthew T.

    2012-05-01

    Applying surface coatings to alloying anodes for Li-ion batteries can improve rate capability and cycle life, but it is unclear how this second phase affects mechanical deformation during electrochemical reaction. Here, in-situ transmission electron microscopy is employed to investigate the electrochemical lithiation and delithiation of silicon nanowires (NWs) with copper coatings. When copper is coated on only one sidewall, the NW bilayer structure bends during delithiation due to length changes in the silicon. Tensile hoop stress causes conformal copper coatings to fracture during lithiation without undergoing bending deformation. In addition, in-situ and ex-situ observations indicate that a copper coating plays a role in suppressing volume expansion during lithiation. Finally, the deformation characteristics and dimensional changes of amorphous, polycrystalline, and single-crystalline silicon are compared and related to observed electrochemical behavior. This study reveals important aspects of the deformation process of silicon anodes, and the results suggest that metallic coatings can be used to improve rate behavior and to manage or direct volume expansion in optimized silicon anode frameworks. © 2012 Elsevier Ltd.

  13. Theoretical study of sorption and diffusion of lithium atoms on the surface of crystalline silicon and inside it

    Science.gov (United States)

    Kuzubov, A. A.; Eliseeva, N. S.; Popov, Z. I.; Fedorov, A. S.; Serzhantova, M. V.; Denisov, V. M.; Tomilin, F. N.

    2013-08-01

    The energy of the sorption and diffusion of lithium atoms on the reconstructed (4 × 2) (100) silicon surface in the process of their transport into near-surface layers, as well as inside crystalline silicon, at various lithium concentrations have been investigated within the density functional theory. It has been shown that single lithium atoms easily migrate on the (100) surface and gradually fill the surface states (T3 and L) located in channels between silicon dimers. The diffusion of lithium into near-surface silicon layers is hampered because of high potential barriers of the transition (1.22 eV). The dependences of the binding energy, potential barriers, and diffusion coefficient inside silicon on distances to the nearest lithium atoms have also been examined. It has been shown that an increase in the concentration of lithium to the Li0.5Si composition significantly reduces the transition energy (from 0.90 to 0.36 eV) and strongly increases (by one to three orders of magnitude) the lithium diffusion rate.

  14. Photoluminescence from nanoparticles of silicon embedded in an amorphous silicon dioxide matrix

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu-Iwayama, Tsutomu (Aichi Univ. of Education (Japan). Dept. of Materials Science); Nakao, Setsuo; Saitoh, Kazuo (National Industrial Research Inst., Nagoya (Japan)); Itoh, Noriaki (Nagoya Univ. (Japan). Dept. of Physics)

    1994-09-26

    We have investigated visible photoluminescence related to nanometre-sized Si crystals in thermal oxide films grown on a crystalline Si wafer, created by a Si[sup +]-implantation and subsequent annealing in a vacuum at 1100[sup o]C (the temperature at which SiO[sub x] decomposes into Si and SiO[sub 2]). Evidence for the formation of Si nanocrystals by annealing at 1100[sup o]C is presented by transmission electron microscopy. The shape of the emission spectrum of the photoluminescence is found to be independent of both excitation energy and annealing time, while the excitation spectrum of the photoluminescence increases as the photon energy increases and its shape depends on annealing time. The results indicate that the photons are absorbed by nanometre-sized Si crystals, for which the band gap is modified by the quantum confinement, and that the emission of photons is not due to direct electron-hole recombination inside Si nanocrystals but is related to defects probably at the interface between Si nanocrystals and SiO[sub 2]. (Author).

  15. Improvement of the Crystallinity of Silicon Films Deposited by Hot-Wire Chemical Vapor Deposition with Negative Substrate Bias

    Science.gov (United States)

    Zhang, Lei; Shen, Honglie; You, Jiayi

    2013-08-01

    We have investigated the effect of negative substrate bias on microcrystalline silicon films deposited on glass and stainless steel by hot-wire chemical vapor deposition (HWCVD) to gain insight into the effect of negative substrate bias on crystallization. Structural characterization of the silicon films was performed by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. It was found that the crystallinity of the films is obviously improved by applying the substrate bias, especially for films on stainless steel. At hot-wire temperature of 1800°C and negative substrate bias of -800 V, grain size as large as 200 nm was obtained on stainless-steel substrate with crystalline fraction 9% higher than that of films deposited on glass and 15% higher than that of films deposited without substrate bias. It is deduced that the improvement of the crystallinity is mainly related to the accelerated electrons emitted from the hot wires. The differences in this improvement between different substrates are caused by the different electrical potential of the substrates. A solar cell fabricated by HWCVD with -800 V substrate bias is demonstrated, showing an obviously higher conversion efficiency than that without substrate bias.

  16. Performance characterization of thin-film-silicon based solar modules under clouded and clear sky conditions in comparison to crystalline silicon modules

    Science.gov (United States)

    Weicht, J. A.; Rasch, R.; Behrens, G.; Hamelmann, F. U.

    2016-07-01

    For a precise prediction of the energy yield of amorphous ( a-Si) and amorphous-microcrystalline tandem ( a-Si/ μc-Si) thinfilm-silicon photovoltaic (PV) modules it is important to know their performance ratio under different light conditions. The efficiency of solar modules is an important value for the monitoring and planning of PV-systems. The efficiency of a-Si solar modules shows no significant changes in the performance ratio at clouded or clear sky conditions. The efficiency of crystalline silicon-based ( c-Si) and a-Si/ μc-Si solar modules shows a lower efficiency for fully clouded conditions without direct irradiation compared to conditions with direct irradiation (clear sky). [Figure not available: see fulltext.

  17. Low-Temperature Crystalline Titanium Dioxide by Atomic Layer Deposition for Dye-Sensitized Solar Cells

    KAUST Repository

    Chandiran, Aravind Kumar

    2013-04-24

    Low-temperature processing of dye-sensitized solar cells (DSCs) is crucial to enable commercialization with low-cost, plastic substrates. Prior studies have focused on mechanical compression of premade particles on plastic or glass substrates; however, this did not yield sufficient interconnections for good carrier transport. Furthermore, such compression can lead to more heterogeneous porosity. To circumvent these problems, we have developed a low-temperature processing route for photoanodes where crystalline TiO2 is deposited onto well-defined, mesoporous templates. The TiO2 is grown by atomic layer deposition (ALD), and the crystalline films are achieved at a growth temperature of 200 C. The ALD TiO2 thickness was systematically studied in terms of charge transport and performance to lead to optimized photovoltaic performance. We found that a 15 nm TiO2 overlayer on an 8 μm thick SiO2 film leads to a high power conversion efficiency of 7.1% with the state-of-the-art zinc porphyrin sensitizer and cobalt bipyridine redox mediator. © 2013 American Chemical Society.

  18. Germanium Nanocrystals Embedded in Silicon Dioxide for Floating Gate Memory Devices

    Directory of Open Access Journals (Sweden)

    A. Bag

    2011-01-01

    Full Text Available Metal-oxide-semiconductor (MOS capacitors with tri-layer structure consisting of rf magnetron sputtered grown germanium (Ge nanocrystals (NCs and silicon dioxide (SiO2 layers sandwiched between thermally grown tunnel and sputtered grown cap oxide layers of SiO2 were fabricated on p-Si substrates. Plane view transmission electron micrographs revealed the formation of spherically shaped and uniformly distributed Ge NCs. The optical and electronic characteristics of tri-layer structures were studied through photoluminescence (PL spectroscopy and capacitance-voltage (C-V measurements, respectively. Frequency dependent electrical properties of the structures have been studied. The optical emission characteristics support the confinement of the carriers in Ge NCs embedded in oxide matrices. An anticlockwise hysteresis in C-V characteristics suggests electron injection and trapping in Ge NCs.

  19. Optical Properties of Spin-Coated TiO2 Antireflection Films on Textured Single-Crystalline Silicon Substrates

    Directory of Open Access Journals (Sweden)

    Ryosuke Watanabe

    2015-01-01

    Full Text Available Antireflection coating (ARC prepared by a wet process is beneficial for low cost fabrication of photovoltaic cells. In this study, we investigated optical properties and morphologies of spin-coated TiO2 ARCs on alkaline textured single-crystalline silicon wafers. Reflectance spectra of the spin-coated ARCs on alkaline textured silicon wafers exhibit no interferences and low reflectance values in the entire visible range. We modeled the structures of the spin-coated films for ray tracing numerical calculation and compared numerically calculated reflectance spectra with the experimental results. This is the first report to clarify the novel optical properties experimentally and theoretically. Optical properties of the spin-coated ARCs without interference are due to the fractional nonuniformity of the thickness of the spin-coated ARCs that cancels out the interference of the incident light.

  20. In-Situ Measurement of Power Loss for Crystalline Silicon Modules Undergoing Thermal Cycling and Mechanical Loading Stress Testing

    DEFF Research Database (Denmark)

    Spataru, Sergiu; Hacke, Peter; Sera, Dezso

    We analyze the degradation of multi-crystalline silicon photovoltaic modules undergoing simultaneous thermal, mechanical, and humidity-freeze stress testing to develop a dark environmental chamber in-situ measurement procedure for determining module power loss. We analyze dark I-V curves measured...... due to cell fractures, and the additional series resistance losses observed under illumination. Based on the analysis, we propose an in-situ module power loss monitoring procedure that relies on dark current-voltage measurements taken during the stress test and initial and final module flash testing...

  1. Operando XPS Characterization of Selective Contacts: The Case of Molybdenum Oxide for Crystalline Silicon Heterojunction Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Laura; Harvey, Stephen P.; Teeter, Glenn; Bertoni, Mariana I.

    2016-11-21

    We demonstrate the potential of X-ray photoelectron spectroscopy (XPS) to characterize new carrier-selective contacts (CSC) for solar cell application. We show that XPS not only provides information about the surface chemical properties of the CSC material, but that operando XPS, i.e. under light bias condition, can also directly measure the photovoltage that develops at the CSC/absorber interface, revealing device relevant information without the need of assembling a full solar cell. We present the application of the technique to molybdenum oxide hole-selective contact films on a crystalline silicon absorber.

  2. Channeling and Radiation of Electrons in Silicon Single Crystals and Si1−xGex Crystalline Undulators

    DEFF Research Database (Denmark)

    Backe, H.; Krambrich, D.; Lauth, W.

    2013-01-01

    potential of the silicon single crystals. Radiation from a crystalline undulator, produced at the Aarhus University (UAAR), has been investigated at the Mainz Microtron electron accelerator facility MAMI. The 4-period epitaxially grown strained layer Si1−xGex undulator had a period length λu = 9.9 μm....... At a beam energy of 375 MeV a broad excess yield around the theoretically expected photon energy of 0.132 MeV has been observed. Model calculations on the basis of synchrotron-like radiation emission suggest that evidence for a weak undulator effect has been observed....

  3. Analysis of temperature and impurity distributions in a unidirectional-solidification process for multi-crystalline silicon of solar cells by a global model

    Energy Technology Data Exchange (ETDEWEB)

    Kakimoto, Koichi [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga 816-8580 (Japan)]. E-mail: kakimoto@riam.kyushu-u.ac.jp; Liu Lijun [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga 816-8580 (Japan); Nakano, Satoshi [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga 816-8580 (Japan)

    2006-10-15

    The unidirectional-solidification process is a key method for large-scale production of multi-crystalline silicon for use in highly efficient solar cells in the photovoltaic industry. Since the efficiency of solar cells depends on the crystal quality of the multi-crystalline silicon, it is necessary to optimize the unidirectional-solidification process to control temperature and impurity distributions in a silicon ingot. We developed a transient global model for the unidirectional-solidification process. We carried out calculations to investigate the temperature and impurity distributions in a silicon ingot during solidification. Conductive heat transfer and radiative heat exchange in a unidirectional-solidification furnace and convective heat transfer in the melt in a crucible are coupled to each other. These heat exchanges were solved iteratively by a finite volume method in a transient condition. Time-dependent distributions of impurity and temperature in a silicon ingot during the unidirectional-solidification process were numerically investigated.

  4. Phase selective growth and characterization of vanadium dioxide films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Tomo; Okimura, Kunio [School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Hajiri, Tetsuya; Kimura, Shin-ichi [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Sakai, Joe [GREMAN, UMR 7347 CNRS, Universite Francois Rabelais de Tours, Parc de Grandmont, 37200 Tours (France)

    2013-04-28

    We report on selective growth of VO{sub 2} films with M1, M2, and intermediate T phases on silicon (Si) substrates by using inductively coupled plasma (ICP)-assisted sputtering (ICPS) under particular conditions. The film composed of M2 phase was proved to be under strong in-plane compressive stress, which is consistent with stress-induced M2 phase. Crystalline structural phase transition (SPT) properties of these films were demonstrated together with infrared light transmittance as a measure of insulator-metal transition (IMT) against temperature. Characteristic correlations between SPT and IMT for films with M2 and intermediate-T phases were reported. Ultraviolet photoelectron spectroscopy measurements probed an energy gap of the film in the M2 phase at around 0.4 eV from the Fermi level indicating the presence of a Mott gap.

  5. Crystalline Silicon Interconnected Strips (XIS). Introduction to a New, Integrated Device and Module Concept

    Energy Technology Data Exchange (ETDEWEB)

    Van Roosmalen, J.; Bronsveld, P.; Mewe, A.; Janssen, G.; Stodolny, M.; Cobussen-Pool, E.; Bennett, I.; Weeber, A.; Geerligs, B. [ECN Solar Energy, P.O. Box 1, NL-1755 ZG, Petten (Netherlands)

    2012-06-15

    A new device concept for high efficiency, low cost, wafer based silicon solar cells is introduced. To significantly lower the costs of Si photovoltaics, high efficiencies and large reductions of metals and silicon costs are required. To enable this, the device architecture was adapted into low current devices by applying thin silicon strips, to which a special high efficiency back-contact heterojunction cell design was applied. Standard industrial production processes can be used for our fully integrated cell and module design, with a cost reduction potential below 0.5 euro/Wp. First devices have been realized demonstrating the principle of a series connected back contact hybrid silicon heterojunction module concept.

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

    Science.gov (United States)

    Bansal, Narottam P.

    1988-01-01

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

  7. Ultrathin, transferred layers of thermally grown silicon dioxide as biofluid barriers for biointegrated flexible electronic systems

    Science.gov (United States)

    Fang, Hui; Zhao, Jianing; Yu, Ki Jun; Song, Enming; Barati Farimani, Amir; Chiang, Chia-Han; Jin, Xin; Xue, Yeguang; Xu, Dong; Du, Wenbo; Seo, Kyung Jin; Zhong, Yiding; Yang, Zijian; Won, Sang Min; Fang, Guanhua; Choi, Seo Woo; Chaudhuri, Santanu; Huang, Yonggang; Ashraful Alam, Muhammad; Viventi, Jonathan; Aluru, N. R.; Rogers, John A.

    2016-10-01

    Materials that can serve as long-lived barriers to biofluids are essential to the development of any type of chronic electronic implant. Devices such as cardiac pacemakers and cochlear implants use bulk metal or ceramic packages as hermetic enclosures for the electronics. Emerging classes of flexible, biointegrated electronic systems demand similar levels of isolation from biofluids but with thin, compliant films that can simultaneously serve as biointerfaces for sensing and/or actuation while in contact with the soft, curved, and moving surfaces of target organs. This paper introduces a solution to this materials challenge that combines (i) ultrathin, pristine layers of silicon dioxide (SiO2) thermally grown on device-grade silicon wafers, and (ii) processing schemes that allow integration of these materials onto flexible electronic platforms. Accelerated lifetime tests suggest robust barrier characteristics on timescales that approach 70 y, in layers that are sufficiently thin (less than 1 μm) to avoid significant compromises in mechanical flexibility or in electrical interface fidelity. Detailed studies of temperature- and thickness-dependent electrical and physical properties reveal the key characteristics. Molecular simulations highlight essential aspects of the chemistry that governs interactions between the SiO2 and surrounding water. Examples of use with passive and active components in high-performance flexible electronic devices suggest broad utility in advanced chronic implants.

  8. Low temperature surface passivation of crystalline silicon and its application to interdigitated back contact silicon heterojunction (ibc-shj) solar cell

    Science.gov (United States)

    Shu, Zhan

    With the absence of shading loss together with improved quality of surface passivation introduced by low temperature processed amorphous silicon crystalline silicon (a-Si:H/c-Si) heterojunction, the interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell exhibits a potential for higher conversion efficiency and lower cost than a traditional front contact diffused junction solar cell. In such solar cells, the front surface passivation is of great importance to achieve both high open-circuit voltage (Voc) and short-circuit current (Jsc). Therefore, the motivation of this work is to develop a low temperature processed structure for the front surface passivation of IBC-SHJ solar cells, which must have an excellent and stable passivation quality as well as a good anti-reflection property. Four different thin film materials/structures were studied and evaluated for this purpose, namely: amorphous silicon nitride (a-SiNx:H), thick amorphous silicon film (a-Si:H), amorphous silicon/silicon nitride/silicon carbide (a-Si:H/a-SiN x:H/a-SiC:H) stack structure with an ultra-thin a-Si:H layer, and zinc sulfide (ZnS). It was demonstrated that the a-Si:H/a-SiNx:H/a-SiC:H stack surpasses other candidates due to both of its excellent surface passivation quality (SRVsolar cells using the stack structure for front surface passivation. Direct comparison shows that such low temperature deposited stack structure developed in this work achieves comparable device performance to the high temperature processed front surface passivation structure used in other high efficiency IBC solar cells. However, the lower fill factor (FF) of IBC-SHJ solar cell as compared with traditional front a-Si:H/c-Si heterojunction cell (HIT cell) greatly limits the overall performance of these devices. Two-dimensional (2D) simulations were used to comparatively model the HIT and IBC-SHJ solar cells to understand the underlying device physics which controls cell performance. The effects of a wide

  9. Si-C Linked Organic Monolayers on Crystalline Silicon Surfaces as Alternative Gate Insulators

    NARCIS (Netherlands)

    Faber, Erik J.; Smet, de Louis C.P.M.; Olthuis, Wouter; Zuilhof, Han; Sudhölter, Ernst J.R.; Bergveld, Piet; Berg, van den Albert

    2005-01-01

    Herein, the influence of silicon surface modification via Si-CnH2n+1 (n=10,12,16,22) monolayer-based devices on p-type (100) and n-type (100) silicon is studied by forming MIS (metal–insulator–semiconductor) diodes using a mercury probe. From current density–voltage (J–V) and capacitance–voltage (C–

  10. Effect of titanium dioxide crystalline structure on the photocatalytic production of hydrogen.

    Science.gov (United States)

    Chiarello, Gian Luca; Di Paola, Agatino; Palmisano, Leonardo; Selli, Elena

    2011-03-02

    The effect of the crystalline phase of TiO(2) (anatase, rutile and brookite) on its photocatalytic activity in hydrogen production from methanol-water vapours has been investigated by testing a series of both home-made and commercial TiO(2) photocatalysts, either bare or surface-modified by deposition of a fixed amount, i.e. 1 wt%, of platinum as co-catalyst. For all of the TiO(2) samples the rate of hydrogen production increased by one order of magnitude upon Pt deposition, because of the ability of Pt to enhance the separation of photoproduced electron-hole pairs. Under irradiation in the 350-450 nm wavelength range, brookite and anatase showed similar photoactivities, both superior to that of rutile. By contrast, rutile, possessing a narrower band gap, was active also under visible light (λ > 400 nm), whereas no hydrogen evolution was observed with anatase and brookite under such conditions. Surface area proved to be a key parameter, strongly influencing photoactivity. However, as the particle size became ultra-small, the semiconductor absorption edge was blue-shifted because of size quantisation effects, with a consequent decrease in hydrogen production rate due to the smaller portion of incident photons absorbed by the photocatalyst.

  11. Single-crystalline titanium dioxide hollow tetragonal nanocones with large exposed (101) facets for excellent photocatalysis.

    Science.gov (United States)

    Wu, Zhengcui; Xue, Yejing; Zou, Zexian; Wang, Xia; Gao, Feng

    2017-03-15

    Crystal facet engineering and surface modification of semiconductor have become important strategies to improve photocatalytic activity by optimizing surface charge carrier separation/transfer and extending solar spectrum utilization. In this work, we report anatase single-crystalline TiO2 hollow tetragonal nanocones with large exposed (101) facets by a facile liquid-phase interfacial synthetic strategy, using the hydrolysis of tetrabutyltitanate with adscititious water in the organic solvent of cyclohexane and a capping agent of 1, 6-hexanediamine. The specific surface area of these TiO2 hollow tetragonal nanocones is as high as 331.3m(2)/g. Thanks to large exposed (101) facets and high surface area, these TiO2 hollow tetragonal nanocones exhibited excellent full-arc photocatalytic activities for the degradation of organic pollutants. Remarkably, the butoxy group could be modified onto TiO2 hollow tetragonal nanocones through post-synthesis treatment in tetrabutyltitanate glycol solution, which brought about eximious visible light photocatalytic activities for the degradation of colored dyes of RhB and MO, especially for RhB, by virtue of much improved electron trapping ability of the Ti-O group from the excited dye due to the strong electronegativity of the oxygen atom in the butoxy group. This work advances us to rationally tailor the atomic and electronic structure of the photocatalyst for outstanding photocatalytic properties in various environmental and energy-related applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Optoelectronic properties of Black-Silicon generated through inductively coupled plasma (ICP) processing for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, Jens, E-mail: J.Hirsch@emw.hs-anhalt.de [Anhalt University of Applied Sciences, Faculty EMW, Bernburger Str. 55, DE-06366 Köthen (Germany); Fraunhofer Center for Silicon Photovoltaics CSP, Otto-Eißfeldt-Str. 12, DE-06120 Halle (Saale) (Germany); Gaudig, Maria; Bernhard, Norbert [Anhalt University of Applied Sciences, Faculty EMW, Bernburger Str. 55, DE-06366 Köthen (Germany); Lausch, Dominik [Fraunhofer Center for Silicon Photovoltaics CSP, Otto-Eißfeldt-Str. 12, DE-06120 Halle (Saale) (Germany)

    2016-06-30

    Highlights: • Fabrication of black silicon through inductively coupled plasma (ICP) processing. • Suppressed formation a self-bias and therefore a reduced ion bombardment of the silicon sample. • Reduction of the average hemispherical reflection between 300 and 1120 nm up to 8% within 5 min ICP process time. • Reflection is almost independent of the angle of incidence up to 60°. • 2.5 ms effective lifetime at 10{sup 15} cm{sup −3} MCD after ALD Al{sub 2}O{sub 3} surface passivation. - Abstract: The optoelectronic properties of maskless inductively coupled plasma (ICP) generated black silicon through SF{sub 6} and O{sub 2} are analyzed by using reflection measurements, scanning electron microscopy (SEM) and quasi steady state photoconductivity (QSSPC). The results are discussed and compared to capacitively coupled plasma (CCP) and industrial standard wet chemical textures. The ICP process forms parabolic like surface structures in a scale of 500 nm. This surface structure reduces the average hemispherical reflection between 300 and 1120 nm up to 8%. Additionally, the ICP texture shows a weak increase of the hemispherical reflection under tilted angles of incidence up to 60°. Furthermore, we report that the ICP process is independent of the crystal orientation and the surface roughness. This allows the texturing of monocrystalline, multicrystalline and kerf-less wafers using the same parameter set. The ICP generation of black silicon does not apply a self-bias on the silicon sample. Therefore, the silicon sample is exposed to a reduced ion bombardment, which reduces the plasma induced surface damage. This leads to an enhancement of the effective charge carrier lifetime up to 2.5 ms at 10{sup 15} cm{sup −3} minority carrier density (MCD) after an atomic layer deposition (ALD) with Al{sub 2}O{sub 3}. Since excellent etch results were obtained already after 4 min process time, we conclude that the ICP generation of black silicon is a promising technique

  13. Comparative study of the reliability of MPPT algorithms for the crystalline silicon photovoltaic modules in variable weather conditions

    Directory of Open Access Journals (Sweden)

    Abraham Dandoussou

    2017-05-01

    Full Text Available The crystalline silicon photovoltaic modules are widely used as power supply sources in the tropical areas where the weather conditions change abruptly. Fortunately, many MPPT algorithms are implemented to improve their performance. In the other hand, it is well known that these power supply sources are nonlinear dipoles and so, their intrinsic parameters may vary with the irradiance and the temperature. In this paper, the MPPT algorithms widely used, i.e. Perturb and Observe (P&O, Incremental Conductance (INC, Hill-Climbing (HC, are implemented using Matlab®/Simulink® model of a crystalline silicon photovoltaic module whose intrinsic parameters were extracted by fitting the I(V characteristic to experimental points. Comparing the simulation results, it is obvious that the variable step size INC algorithm has the best reliability than both HC and P&O algorithms for the near to real Simulink® model of photovoltaic modules. With a 60 Wp photovoltaic module, the daily maximum power reaches 50.76 W against 34.40 W when the photovoltaic parameters are fixed. Meanwhile, the daily average energy is 263 Wh/day against 195 Wh/day.

  14. Thin film PV standing tall side-by-side with multi-crystalline silicon: also in terms of reliability

    Science.gov (United States)

    Dhere, Neelkanth G.; Ward, Allan; Wieting, Robert; Guha, Subhendu; Dhere, Ramesh G.

    2015-09-01

    Triple junction hydrogenated amorphous silicon (a-Si:H) have shown exceptionally good reliability and durability. Cadmium telluride, CdTe PV modules have shown the lowest production cost without subsidies. Copper-indium gallium selenide sulfide (CIGS) and cadmium telluride (CdTe) cells and modules have been showing efficiencies equal or greater than those of multi-crystalline, (mx-Si), PV modules. Early generation CIGS and CdTe PV modules had a different qualification standard 61646 as compared to 61215 for crystalline silicon, (c-Si), PV modules. This, together with small vulnerability in harsh climates, was used to create doubts about their reliability. Recently CdTe and CIGS glass-to-glass modules have passed the rigorous accelerated tests, especially as long as the edge seals are not compromised. Moreover, the cumulative shipment of these modules is more than 12 GW demonstrating the customer confidence in these products. Hence it can be stated that also in terms of the reliability and durability all the thin film PV modules stand tall and compare favorably with mx-Si.

  15. Ink jet printable silver metallization with zinc oxide for front side metallization for micro crystalline silicon solar cells

    Science.gov (United States)

    Jurk, Robert; Fritsch, Marco; Eberstein, Markus; Schilm, Jochen; Uhlig, Florian; Waltinger, Andreas; Michaelis, Alexander

    2015-12-01

    Ink jet printable water based inks are prepared by a new silver nanoparticle synthesis and the addition of nanoscaled ZnO particles. For the formation of front side contacts the inks are ink jet printed on the front side of micro crystalline silicon solar cells, and contact the cell directly during the firing step by etching through the wafers’ anti-reflection coating (ARC). In terms of Ag dissolution and precipitation the mechanism of contact formation can be compared to commercial glass containing thick film pastes. This avoids additional processing steps, like laser ablation, which are usually necessary to open the ARC prior to ink jet printing. As a consequence process costs can be reduced. In order to optimize the ARC etching and contact formation during firing, zinc oxide nanoparticles are investigated as an ink additive. By utilization of in situ contact resistivity measurements the mechanism of contacting was explored. Our results show that silver inks containing ZnO particles realize a specific contact resistance below 10 mΩṡcm2. By using a multi-pass ink jet printing and plating process a front side metallization of commercial 6  ×  6 inch2 standard micro crystalline silicone solar cells with emitter resistance of 60 Ω/◽ was achieved and showed an efficiency of 15.7%.

  16. Effect of the initial structure on the electrical property of crystalline silicon films deposited on glass by hot-wire chemical vapor deposition.

    Science.gov (United States)

    Chung, Yung-Bin; Lee, Sang-Hoon; Bae, Sung-Hwan; Park, Hyung-Ki; Jung, Jae-Soo; Hwang, Nong-Moon

    2012-07-01

    Crystalline silicon films on an inexpensive glass substrate are currently prepared by depositing an amorphous silicon film and then crystallizing it by excimer laser annealing, rapid thermal annealing, or metal-induced crystallization because crystalline silicon films cannot be directly deposited on glass at a low temperature. It was recently shown that by adding HCI gas in the hot-wire chemical vapor deposition (HWCVD) process, the crystalline silicon film can be directly deposited on a glass substrate without additional annealing. The electrical properties of silicon films prepared using a gas mixture of SiH4 and HCl in the HWCVD process could be further improved by controlling the initial structure, which was achieved by adjusting the delay time in deposition. The size of the silicon particles in the initial structure increased with increasing delay time, which increased the mobility and decreased the resistivity of the deposited films. The 0 and 5 min delay times produced the silicon particle sizes of approximately 10 and approximately 28 nm, respectively, in the initial microstructure, which produced the final films, after deposition for 300 sec, of resistivities of 0.32 and 0.13 Omega-cm, mobilities of 1.06 and 1.48 cm2 V(-1) S(-1), and relative densities of 0.87 and 0.92, respectively.

  17. Morphological and structural evolution of the anatase phase of silicon modified titanium dioxide obtained by Sol-gel; Evolucao estrutural e morfologica da fase anatase de dioxido de titanio modificada com silicio obtido pelo Metodo Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, S.A.; Oliveira, C.T.; Ciola, R.A.; Cavalheiro, A.A., E-mail: silvanicelopes@gmail.com [Universidade Estadual de Mato Grosso do Sul (CPTREN/UEMS), Navirai, MS (Brazil). Centro de Pesquisas Tecnologicas em Recursos Naturais

    2011-07-01

    The photonic efficiency of the titanium dioxide photocatalyst is dependent on the crystalline structure and the anatase phase presents high efficiency in the border region between the UV-B and UV-A, with a redox potential sufficient to generate hydroxyl radicals and superoxide ion in order to oxidate organic compounds. In spite of the organic matter degradation effectiveness, the efficiency can be reduced substantially due to the presence of crystalline defects, which act as premature recombination centers of the electron-hole pair. The increasing of calcining temperature allows the elimination of most of these defects, but the structural ordering at temperatures around 600°C eventually leads to the phase transition toward rutile, which is not photoactive. In this work, it was demonstrated through FTIR and XRD that the silicon modifier presence stabilizes the anatase phase even at temperatures as high as 900°C. (author)

  18. Size-, surface- and crystalline structure composition-related effects of titanium dioxide nanoparticles during their aquatic life cycle.

    Science.gov (United States)

    Seitz, Frank; Rosenfeldt, Ricki R; Schneider, Sandra; Schulz, Ralf; Bundschuh, Mirco

    2014-09-15

    Nanoparticle toxicity depends amongst others on particle characteristics and nanoparticle behavior during their aquatic life cycle. Aquatic organisms may be exposed to nanoparticle agglomerates of varying size, while lager agglomerates after settling rather affect benthic organisms. In this context, the present study systematically examined the role of particle characteristics, i.e. crystalline structure composition (anatase as well as mixture of anatase-rutile), initial particle size (55-, 100-, and 140-nm) and surface area, in the toxicity of titanium dioxide nanoparticles (nTiO2) to the pelagic filter feeder Daphnia magna (n = 4) and the benthic amphipod Gammarus fossarum (n = 30). Smaller initial particle sizes (i.e. 55-nm) and anatase based particles showed an approximately 90% lower Daphnia EC50-value compared to its respective counterpart. Most importantly, particle surface normalized EC50-values significantly differed for nanoparticles equal to or below 100 nm in size from 140-nm sized particles. Hence, these data suggest that the reactive initial surface area may explain the ecotoxicological potential of different particle size classes only if their size is smaller or around 100 nm. In contrast to Daphnia, Gammarus was not affected by nTiO2 concentrations of up to 5.00 mg/L, irrespective of their characteristics. This indicates fundamental differences in the toxicity of nTiO2 during its aquatic life cycle mediated by alterations in their characteristics over time.

  19. Research on the effects of machining-induced subsurface damages on mono-crystalline silicon via molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Hongwei, E-mail: hwzhao@jlu.edu.cn [College of Mechanical Science and Engineering, Jilin University, 5988 Renmin Street, Changchun, Jilin 130025 (China); Shi Chengli; Zhang Peng; Zhang Lin; Huang Hu; Yan Jiwang [College of Mechanical Science and Engineering, Jilin University, 5988 Renmin Street, Changchun, Jilin 130025 (China)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer MD simulations of nano-cutting process are carried out to obtain machining-induced subsurface with diamond cutting tools. Black-Right-Pointing-Pointer After cutting, the crystal lattice reconstructed and led to the formation of the machined surface. Black-Right-Pointing-Pointer The mechanical properties of the pristine and machining-induced subsurface Si are studied by means of nanoindentation. Black-Right-Pointing-Pointer Nanoindentation results show that the hardness of the machined surface was smaller than mono-crystalline Si. - Abstract: Nanoindentation simulation via molecular dynamic (MD) method was carried out to investigate the characteristics of machining-induced subsurface damage of mono-crystalline silicon with a spherical diamond indenter. In this study, MD simulations of nano-cutting process were carried out firstly to cut through the specimen's surface with diamond cutting tools of different edge radius of 0 nm, 3 nm and 5 nm respectively. Then, MD simulation of nanoindentation on the machined surface was carried out. Tersoff potential was used to model the interaction of Si atoms, and the interaction between Si and C atoms was modeled by Morse potential. Simulational results indicate that during cutting process, the specimen undergo plastic deformation and phase transformation. After cutting process, the crystal lattice reconstructs and the residual amorphous layers lead to the formation of the machined surface. Nanoindentation results show that the hardness of the machined surface is smaller than mono-crystalline Si. So in order to get accurate properties of the pristine silicon or other semiconductor materials via experiments, the amorphous phase should be completely removed or it would influence the mechanical properties of the pristine materials.

  20. Hydrogen passivation of electrically active defects in crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Milstein, J B; Tsuo, Y S; Osterwald, C R; White, C W

    1984-06-01

    We have observed significant improvements in the efficiencies of dendritic web and edge-supported-pulling (ESP) silicon sheet solar cells after hydrogen ion beam passivation for a period of ten minutes or less. We have studied the effects of the hydrogen ion beam treatment with respect to silicon material damage, silicon sputter rate, introduction of impurities, and changes in reflectance. We have determined that the silicon sputter rate for a constant ion beam flux of 0.60 +- 0.05 mA/cm/sup 2/ exhibits a maximum at approximately 1400 eV ion beam energy. We have observed that hydrogen ion beam treatment can result in a reduced fill factor, which is caused by damage to the front metallization of the cell rather than by damage to the p-n junction.

  1. Si-C linked organic monolayers on crystalline silicon surfaces as alternative gate insulators

    NARCIS (Netherlands)

    Faber, E.J.; Smet, de L.C.P.M.; Olthuis, W.; Zuilhof, H.; Sudhölter, E.J.R.; Bergveld, P.; Berg, van den A.

    2005-01-01

    Herein, the influence of silicon surface modification via SiCnH2n+1 (n=10,12,16,22) monolayer-based devices on p-type 100 and n-type 100 silicon is studied by forming MIS (metal-insulator-semiconductor) diodes using a mercury probe. From current density-voltage (J-V) and capacitance-voltage (C-V) me

  2. Si-C linked organic monolayers on crystalline silicon surfaces as alternative gate insulators

    NARCIS (Netherlands)

    Faber, E.J.; Smet, de L.C.P.M.; Olthuis, W.; Zuilhof, H.; Sudhölter, E.J.R.; Bergveld, P.; Berg, van den A.

    2005-01-01

    Herein, the influence of silicon surface modification via SiCnH2n+1 (n=10,12,16,22) monolayer-based devices on p-type 100 and n-type 100 silicon is studied by forming MIS (metal-insulator-semiconductor) diodes using a mercury probe. From current density-voltage (J-V) and capacitance-voltage (C-V)

  3. Single-Crystalline Silicon Solar Cell with Selective Emitter Formed by Screen Printing and Chemical Etching Method: A Feasibility Study

    Directory of Open Access Journals (Sweden)

    Yen-Po Chen

    2013-01-01

    Full Text Available A new method for fabricating crystalline silicon solar cells with selective emitters is presented. In this method, shallow trenches corresponding to metal contact area are first formed by screen printing and chemical etching, followed by heavy doping over the whole front surface of the silicon wafer. After a polymer mask is pasted by aligned screen-printing to cover the shallow trenches, the silicon wafer is etched such that the heavy doping remains at the shallow trench area, while other areas become lightly doped. With the presented method, two screening printing steps are required for obtaining a selective emitter structure on a solar wafer. Compared with existing etch-back methods, the presented one is believed to be able to easily conform with present industrial process. Experimental results show that optical responses at the short and long wavelengths were both improved by applying the proposed selective emitter technique to fabricate solar cells with an a-Si:H film deposited on the back surface. The selective emitter cell with a-Si:H back surface deposition had improvements of 1.66 mA/cm2 and 1.23% absolute in Jsc and conversion efficiency, respectively, compared to the reference cell that had a homogeneous emitter and no a-Si:H on the back surface.

  4. Numerical investigation of thermal history and residual stress of grown multi-crystalline silicon at the various growth stages for PV applications

    Science.gov (United States)

    Srinivasan, M.; Ramasamy, P.

    2016-05-01

    The directional solidification is a very important technique for growing high quality multi-crystalline silicon at large scale for PV solar cells. Time dependent numerical modelling of the temperature distribution, residual stress in multi-crystalline silicon ingots grown by directional solidification has been investigated for five growth stage. The computation was carried in a 2D axis symmetric model by the finite volume method. The history of temperature distribution, stress generation, are tracked in our modelling continuously to consider the growth process from the beginning to the end of solidification process. This paper is aimed to achieve an advanced understanding of the thermal and mechanical behavior of grown crystal.

  5. 18th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Workshop Proceedings, 3-6 August 2008, Vail, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, B. L.

    2008-09-01

    The National Center for Photovoltaics sponsored the 18th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, held in Vail, CO, August 3-6, 2008. This meeting provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The theme of this year's meeting was 'New Directions for Rapidly Growing Silicon Technologies.'

  6. Review of the Potential of the Ni/Cu Plating Technique for Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Atteq ur Rehman

    2014-02-01

    Full Text Available Developing a better method for the metallization of silicon solar cells is integral part of realizing superior efficiency. Currently, contact realization using screen printing is the leading technology in the silicon based photovoltaic industry, as it is simple and fast. However, the problem with metallization of this kind is that it has a lower aspect ratio and higher contact resistance, which limits solar cell efficiency. The mounting cost of silver pastes and decreasing silicon wafer thicknesses encourages silicon solar cell manufacturers to develop fresh metallization techniques involving a lower quantity of silver usage and not relying pressing process of screen printing. In recent times nickel/copper (Ni/Cu based metal plating has emerged as a metallization method that may solve these issues. This paper offers a detailed review and understanding of a Ni/Cu based plating technique for silicon solar cells. The formation of a Ni seed layer by adopting various deposition techniques and a Cu conducting layer using a light induced plating (LIP process are appraised. Unlike screen-printed metallization, a step involving patterning is crucial for opening the masking layer. Consequently, experimental procedures involving patterning methods are also explicated. Lastly, the issues of adhesion, back ground plating, process complexity and reliability for industrial applications are also addressed.

  7. Neutron-activated determination of chlorine, using the /sup 35/Cl(n,p)/sup 35/S reaction as the basis, in thin coatings of silicon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Perezhogin, G.A.

    1988-01-10

    The neutron-activation determination of chlorine in thin coatings of silicon dioxide on silicon has been shown to be possible through the use of the /sup 55/Cl(n, P)/sup 35/S reaction. The detection limit of chlorine is 3 x 10/sup -9/ g (5 x 10/sup 13/ atoms).

  8. Electrical analysis of high dielectric constant insulator and metal gate metal oxide semiconductor capacitors on flexible bulk mono-crystalline silicon

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-06-01

    We report on the electrical study of high dielectric constant insulator and metal gate metal oxide semiconductor capacitors (MOSCAPs) on a flexible ultra-thin (25 μm) silicon fabric which is peeled off using a CMOS compatible process from a standard bulk mono-crystalline silicon substrate. A lifetime projection is extracted using statistical analysis of the ramping voltage (Vramp) breakdown and time dependent dielectric breakdown data. The obtained flexible MOSCAPs operational voltages satisfying the 10 years lifetime benchmark are compared to those of the control MOSCAPs, which are not peeled off from the silicon wafer. © 2014 IEEE.

  9. Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

    Directory of Open Access Journals (Sweden)

    Liyun Yu

    2015-10-01

    Full Text Available One prominent method of modifying the properties of dielectric elastomers (DEs is by adding suitable metal oxide fillers. However, almost all commercially available silicone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting metal oxide filled elastomer may contain too much filler. We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler. Liquid silicone rubber (LSR has relatively low viscosity, which is favorable for loading inorganic fillers. In the present study, four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber (RTV were investigated. The resulting elastomers were evaluated with respect to their dielectric permittivity, tear and tensile strengths, electrical breakdown, thermal stability and dynamic viscosity. Filled silicone elastomers with high loadings of nano-sized titanium dioxide (TiO2 particles were also studied. The best overall performing formulation had 35 wt.% TiO2 nanoparticles in the POWERSIL® XLR LSR, where the excellent ensemble of relative dielectric permittivity of 4.9 at 0.1 Hz, breakdown strength of 160 V µm−1, tear strength of 5.3 MPa, elongation at break of 190%, a Young’s modulus of 0.85 MPa and a 10% strain response (simple tension in a 50 V μm−1 electric field was obtained.

  10. Friction factors of colloidal suspension containing silicon dioxide nanoparticles in water

    Science.gov (United States)

    Tang, Clement; Pant, Sarbottam; Sharif, Md. Tanveer

    2015-11-01

    The purpose of this study is to experimentally characterize the friction factor of a colloidal suspension flow in circular and square tubes. The suspension contained silicon dioxide nanoparticles dispersed in distilled water at 9.58% volume concentration. Rheological measurements indicated that the suspension exhibits non-Newtonian behavior, and could be modelled as a power-law generalized Newtonian fluid. The experimental study showed that, with proper characterization of the consistency and flow behavior indices, the suspension flow friction factors in circular and square tubes exhibit similarities with those of Newtonian fluid flow. In the laminar fully-developed flow region, the Poiseuille numbers are similar to those established for Newtonian fluid flow. In the turbulent region, the Dodge and Metzner relation between the friction factor and a generalized Reynolds number can adequately describe the flow. The onsets of transition to turbulent flow for the suspension vary with the shape of the tube and differ from those of Newtonian fluid flow. The deviations suggest that the flow passage shape and the presence of nanoparticles affect the onset of transition to turbulent flow. Supported by North Dakota NASA EPSCoR.

  11. Thickness-dependent stress in plasma-deposited silicon dioxide films

    Science.gov (United States)

    Au, V.; Charles, C.; Bulla, D. A. P.; Love, J. D.; Boswell, R. W.

    2005-04-01

    Thick silicon dioxide (SiO2) films up to 5 μm have been deposited by helicon activated reactive evaporation (plasma assisted deposition with electron beam evaporation source) as both bilayer and trilayer structures, and the film stress was investigated in the context of optical waveguide fabrication. A model for stress in the SiO2-Si bilayer as a function of film thickness is formulated and interpreted in terms of Volmer-Weber film growth mechanisms. We find that island coalescence begins at a film thickness of less than 165 nm and continues until about 700 nm. Above approximately 1 μm thickness, the film continues growth as a continuous film. The stress in a deposited SiO2 film in an SiO2-Si-SiO2 trilayer structure was investigated by adapting the established Stoney's equation for a trilayer system, and comparing it with a thermally grown SiO2 trilayer. A constant value of stress is obtained for the deposited SiO2 film for film thickness >1μm which was consistently less than both measured and previously reported values of stress in thermally grown SiO2.

  12. Titanium dioxide antireflection coating for silicon solar cells by spray deposition

    Science.gov (United States)

    Kern, W.; Tracy, E.

    1980-01-01

    A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

  13. Silicon-Doped Titanium Dioxide Nanotubes Promoted Bone Formation on Titanium Implants.

    Science.gov (United States)

    Zhao, Xijiang; Wang, Tao; Qian, Shi; Liu, Xuanyong; Sun, Junying; Li, Bin

    2016-02-26

    While titanium (Ti) implants have been extensively used in orthopaedic and dental applications, the intrinsic bioinertness of untreated Ti surface usually results in insufficient osseointegration irrespective of the excellent biocompatibility and mechanical properties of it. In this study, we prepared surface modified Ti substrates in which silicon (Si) was doped into the titanium dioxide (TiO₂) nanotubes on Ti surface using plasma immersion ion implantation (PIII) technology. Compared to TiO₂ nanotubes and Ti alone, Si-doped TiO₂ nanotubes significantly enhanced the expression of genes related to osteogenic differentiation, including Col-I, ALP, Runx2, OCN, and OPN, in mouse pre-osteoblastic MC3T3-E1 cells and deposition of mineral matrix. In vivo, the pull-out mechanical tests after two weeks of implantation in rat femur showed that Si-doped TiO₂ nanotubes improved implant fixation strength by 18% and 54% compared to TiO₂-NT and Ti implants, respectively. Together, findings from this study indicate that Si-doped TiO₂ nanotubes promoted the osteogenic differentiation of osteoblastic cells and improved bone-Ti integration. Therefore, they may have considerable potential for the bioactive surface modification of Ti implants.

  14. Characterization of magnetic biochar amended with silicon dioxide prepared at high temperature calcination

    Directory of Open Access Journals (Sweden)

    Baig Shams Ali

    2016-09-01

    Full Text Available Calcination is considered to increase the hardness of composite material and prevent its breakage for the effective applications in environmental remediation. In this study, magnetic biochar amended with silicon dioxide was calcined at high temperature under nitrogen environment and characterized using various techniques. X-ray diffraction (XRD analysis revealed elimination of Fe3O4 peaks under nitrogen calcination and formation of Fe3Si and iron as major constituents of magnetic biochar-SiO2 composite, which demonstrated its superparamagnetic behavior (>80 A2·kg−1 comparable to magnetic biochar. Thermogravimetric analysis (TGA revealed that both calcined samples generated higher residual mass (>96 % and demonstrated better thermal stability. The presence of various bands in Fourier transform infrared spectroscopy (FT-IR was more obvious and the elimination of H–O–H bonding was observed at high temperature calcination. In addition, scanning electron microscopy (SEM images revealed certain morphological variation among the samples and the presence of more prominent internal and external pores, which then judged the surface area and pore volume of samples. Findings from this study suggests that the selective calcination process could cause useful changes in the material composites and can be effectively employed in environmental remediation measures.

  15. FTIR Characterization of Fluorine Doped Silicon Dioxide Thin Films Deposited by Plasma Enhanced Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Peng-Fei; DING Shi-Jin; ZHANG Wei; ZHANG Jian-Yun; WANGJi-Tao; WEI William Lee

    2000-01-01

    Fluorine doped silicon dioxide (SiOF) thin films have been prepared by plasma enhanced chemical vapor depo sition. The Fourier transform infrared spectrometry (FTIR) spectra of SiOF films are deliberated to reveal the structure change of SiO2 and the mechanism of dielectric constant reduction after doping fluorine. When F is doped in SiO2 films, the Si-O stretching absorption peak will have a blue-shift due to increase of the partial charge of the O atom. The FTIR spectra indicate that some Si-OH components in the thin film can be removed after doping fluorine. These changes reduce the ionic and orientational polarization, and result in the reduction in dielectric constant of the film. According to Gaussian fitting, it is found that the Si-F2 bonds will appear in the SiOF film with increase of the fluorine content. The Si-F2 structures are liable to react with water, and cause the same increase of absorbed moisture in the film.

  16. Nano-silicon dioxide toxicological characterization on two human kidney cell lines

    Science.gov (United States)

    Paget, V.; Sergent, J. A.; Chevillard, S.

    2011-07-01

    Silicon dioxide nanoparticles (n-SiO2) have recently encountered a wide variety of applications in medicine or engineering but their toxicological effects are poorly understood. In this study, we have used SiO2-25 nm and SiO2-100 nm mono-dispersed nanoparticles labeled with Rhodamine B and TMPyP respectively. These two fluorophores were incorporated during synthesis in order to track nanoparticles cell incorporation. Up-to-date, no evaluation of the toxicological effects of these nanoparticles upon human kidney has been published. As kidney is one of the major traditional retention organs, the aim of our study is to evaluate the potential toxicity of these nanoparticles on two human cell lines from proximal tubule (Caki-1 and Hek293). Our results report that the two cell lines do not show similar responses after 24 hours of exposure to SiO2-nanoparticles disregarding a similar origin in the kidney. Interestingly, our results indicate that for both tested SiO2-nanoparticles, Caki-1 cells present a higher sensitivity in terms of cytotoxicity and genotoxicity than Hek293 cells. Furthermore, our results show that for similar concentration of exposure, SiO2-25 nm seems to be more cytotoxic and genotoxic than SiO2-100nm for both tested cell lines.

  17. Nano-silicon dioxide toxicological characterization on two human kidney cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Paget, V; Sergent, J A; Chevillard, S, E-mail: sylvie.chevillard@cea.fr [Laboratory of Experimental Cancerology, Institute of Cellular and Molecular Radiobiology, CEA, Fontenay-aux-Roses (France)

    2011-07-06

    Silicon dioxide nanoparticles (n-SiO{sub 2}) have recently encountered a wide variety of applications in medicine or engineering but their toxicological effects are poorly understood. In this study, we have used SiO{sub 2}-25 nm and SiO{sub 2}-100 nm mono-dispersed nanoparticles labeled with Rhodamine B and TMPyP respectively. These two fluorophores were incorporated during synthesis in order to track nanoparticles cell incorporation. Up-to-date, no evaluation of the toxicological effects of these nanoparticles upon human kidney has been published. As kidney is one of the major traditional retention organs, the aim of our study is to evaluate the potential toxicity of these nanoparticles on two human cell lines from proximal tubule (Caki-1 and Hek293). Our results report that the two cell lines do not show similar responses after 24 hours of exposure to SiO{sub 2}-nanoparticles disregarding a similar origin in the kidney. Interestingly, our results indicate that for both tested SiO{sub 2}-nanoparticles, Caki-1 cells present a higher sensitivity in terms of cytotoxicity and genotoxicity than Hek293 cells. Furthermore, our results show that for similar concentration of exposure, SiO{sub 2}-25 nm seems to be more cytotoxic and genotoxic than SiO{sub 2}-100nm for both tested cell lines.

  18. Adsorption of Cr(VI onto Hybrid Membrane of Carboxymethyl Chitosan and Silicon Dioxide

    Directory of Open Access Journals (Sweden)

    Yanling Deng

    2017-01-01

    Full Text Available In this study, a new adsorbent material was synthesized by using carboxymethyl chitosan and silicon dioxide. The hybrid membrane was used as an adsorbent for the removal of Cr(VI from aqueous solutions. The adsorption potential of Cr(VI by the hybrid materials was investigated by varying experimental conditions such as pH, contact time, and the dosage of the hybrid membrane. Adsorption isotherms of Cr(VI onto the hybrid membrane were studied with varying initial concentrations under optimum experiment conditions. The surface property of the hybrid membrane was characterized by SEM (scanning electron microscope and Fourier transform infrared spectrometer (FTIR. The concentrations of Cr(VI in solution are determined by ICP-AES (inductively coupled plasma atomic emission spectrometry. The present study investigates the adsorption mechanisms of Cr(VI onto the hybrid membrane. The results provide new insight, demonstrating that the modified hybrid membrane can be an efficient adsorbent for Cr(VI from the aqueous solution.

  19. Direct electrochemistry behavior of Cytochrome c on silicon dioxide nanoparticles-modified electrode

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A newfangled direct electrochemistry behavior of Cytochrome c (Cyt c) was found on glassy carbon (GC) electrode modified with the silicon dioxide (SiO2) nanoparticles by physical adsorption. A pair of stable and well-defined redox peaks of Cyt c′ quasi-reversible electrochemical reaction were obtained with a heterogeneous electron transfer rate constant of 1.66×10-3 cm/s and a formal potential of 0.069 V (vs. Ag/AgCl) (0.263 V versus NHE) in 0.1 mol/L pH 6.8 PBS. Both the size and the amount of SiO2 nanoparticles could influence the electron transfer between Cyt c and the electrode. Electrostatic interaction which is between the negative nanoparticle surface and positively charged amino acid residues on the Cyt c surface is of importance for the stability and reproducibility toward the direct electron transfer of Cyt c. It is suggested that the modification of SiO2 nanoparticles proposes a novel approach to realize the direct electrochemistry of proteins.

  20. Silicon dioxide nanoparticles increase macrophage atherogenicity: Stimulation of cellular cytotoxicity, oxidative stress, and triglycerides accumulation.

    Science.gov (United States)

    Petrick, Lauren; Rosenblat, Mira; Paland, Nicole; Aviram, Michael

    2016-06-01

    Nanoparticle research has focused on their toxicity in general, while increasing evidence points to additional specific adverse effects on atherosclerosis development. Arterial macrophage cholesterol and triglyceride (TG) accumulation and foam cell formation are the hallmark of early atherogenesis, leading to cardiovascular events. To investigate the in vitro atherogenic effects of silicon dioxide (SiO2 ), J774.1 cultured macrophages (murine cell line) were incubated with SiO2 nanoparticle (SP, d = 12 nm, 0-20 µg/mL), followed by cellular cytotoxicity, oxidative stress, TG and cholesterol metabolism analyses. A significant dose-dependent increase in oxidative stress (up to 164%), in cytotoxicity (up to 390% measured by lactate dehydrogenase (LDH) release), and in TG content (up to 63%) was observed in SiO2 exposed macrophages compared with control cells. A smaller increase in macrophage cholesterol mass (up to 22%) was noted. TG accumulation in macrophages was not due to a decrease in TG cell secretion or to an increased TG biosynthesis rate, but was the result of attenuated TG hydrolysis secondary to decreased lipase activity and both adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) protein expression (by 42 and 25%, respectively). Overall, SPs showed pro-atherogenic effects on macrophages as observed by cytotoxicity, increased oxidative stress and TG accumulation. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 713-723, 2016.

  1. Adsorption of acids and bases from aqueous solutions onto silicon dioxide particles.

    Science.gov (United States)

    Zengin, Huseyin; Erkan, Belgin

    2009-12-30

    The adsorption of acids and bases onto the surface of silicon dioxide (SiO(2)) particles was systematically studied as a function of several variables, including activation conditions, contact time, specific surface area, particle size, concentration and temperature. The physical properties of SiO(2) particles were investigated, where characterizations were carried out by FT-IR spectroscopy, and morphology was examined by scanning electron microscopy (SEM). The SEM of samples showed good dispersion and uniform SiO(2) particles with an average diameter of about 1-1.5 microm. The adsorption results revealed that SiO(2) surfaces possessed effective interactions with acids and bases, and greatest adsorption capacity was achieved with NaOH, where the best fit isotherm model was the Freundlich adsorption model. The adsorption properties of raw SiO(2) particles were further improved by ultrasonication. Langmuir monolayer adsorption capacity of NaOH adsorbate at 25 degrees C on sonicated SiO(2) (182.6 mg/g) was found to be greater than that of the unsonicated SiO(2) (154.3mg/g). The spontaneity of the adsorption process was established by decreases in DeltaG(ads)(0), which varied from -10.5 to -13.6 kJ mol(-1), in the temperature range 283-338K.

  2. Nano-silicon dioxide mitigates the adverse effects of salt stress on Cucurbita pepo L.

    Science.gov (United States)

    Siddiqui, Manzer H; Al-Whaibi, Mohamed H; Faisal, Mohammad; Al Sahli, Abdulaziz A

    2014-11-01

    Research into nanotechnology, an emerging science, has advanced in almost all fields of technology. The aim of the present study was to evaluate the role of nano-silicon dioxide (nano-SiO2 ) in plant resistance to salt stress through improvement of the antioxidant system of squash (Cucurbita pepo L. cv. white bush marrow). Seeds treated with NaCl showed reduced germination percentage, vigor, length, and fresh and dry weights of the roots and shoots. However, nano-SiO2 improved seed germination and growth characteristics by reducing malondialdehyde and hydrogen peroxide levels as well as electrolyte leakage. In addition, application of nano-SiO2 reduced chlorophyll degradation and enhanced the net photosynthetic rate (Pn ), stomatal conductance (gs ), transpiration rate, and water use efficiency. The increase in plant germination and growth characteristics through application of nano-SiO2 might reflect a reduction in oxidative damage as a result of the expression of antioxidant enzymes, such as catalase, peroxidase, superoxide dismutase, glutathione reductase, and ascorbate peroxidase. These results indicate that nano-SiO2 may improve defense mechanisms of plants against salt stress toxicity by augmenting the Pn , gs , transpiration rate, water use efficiency, total chlorophyll, proline, and carbonic anhydrase activity in the leaves of plants.

  3. Structural and magnetic properties of the nanocomposite materials based on a mesoporous silicon dioxide matrix

    Energy Technology Data Exchange (ETDEWEB)

    Grigor’eva, N. A., E-mail: natali@lns.pnpi.spb.ru [St. Petersburg State University (Russian Federation); Eckerlebe, H. [Helmholtz-Zentrum Geesthacht (Germany); Eliseev, A. A.; Lukashin, A. V.; Napol’skii, K. S. [Moscow State University (Russian Federation); Kraje, M. [Reactor Institute Delft (Netherlands); Grigor’ev, S. V. [St. Petersburg State University (Russian Federation)

    2017-03-15

    The structural and magnetic properties of the mesoporous systems based on silicon dioxide with a regular hexagonal arrangement of pores several microns in length and several nanometers in diameter, which are filled with iron compound nanofilaments in various chemical states, are studied in detail. The studies are performed using the following mutually complementary methods: transmission electron microscopy, SQUID magnetometry, electron spin resonance, Mössbauer spectroscopy, polarized neutron small-angle diffraction, and synchrotron radiation diffraction. It is shown that the iron nanoparticles in pores are mainly in the γ phase of Fe{sub 2}O{sub 3} with a small addition of the α phase and atomic iron clusters. The effective magnetic field acting on a nanofilament from other nanofilaments is 11 mT and has a dipole nature, the ferromagnetic–paramagnetic transition temperature is in the range 76–94 K depending on the annealing temperature of the samples, and the temperature that corresponds to the change in the magnetic state of the iron oxide nanofilaments is T ≈ 50–60 K at H = 0 and T ≈ 80 K at H = 300 mT. It is also shown that the magnetization reversal of an array of nanofilaments is caused by the magnetostatic interaction between nanofilaments at the fields that are lower than the saturation field.

  4. Titanium dioxide antireflection coating for silicon solar cells by spray deposition

    Science.gov (United States)

    Kern, W.; Tracy, E.

    1980-01-01

    A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

  5. Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

    DEFF Research Database (Denmark)

    Yu, Liyun; Skov, Anne Ladegaard

    2016-01-01

    One prominent method of modifying the properties of dielectric elastomers (DEs) is by adding suitable metal oxide fillers. However, almost all commercially available silicone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting...... metal oxide filled elastomer may contain too much filler. We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler. Liquid silicone rubber (LSR) has relatively low viscosity, which is favorable for loading inorganic fillers. In the present...... study, four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber (RTV) were investigated. The resulting elastomers were evaluated with respect to their dielectric permittivity, tear and tensile strengths, electrical breakdown, thermal stability...

  6. Composition and crystallinity of silicon nanoparticles synthesised by hot wire thermal catalytic pyrolysis at different pressures

    CSIR Research Space (South Africa)

    Scriba, MR

    2009-04-01

    Full Text Available The effect of pressure on the structure and composition of silicon nanoparticles synthesized by hot wire thermal catalytic pyrolysis (HW-TCP) of pure silane has been investigated. Light brown powders were produced at silane pressures of 10 and 50...

  7. In-Situ Measurement of Power Loss for Crystalline Silicon Modules Undergoing Thermal Cycling and Mechanical Loading Stress Testing: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Spataru, Sergiu; Hacke, Pater; Sera, Dezso

    2015-09-15

    We analyze the degradation of multi-crystalline silicon photovoltaic modules undergoing simultaneous thermal, mechanical, and humidity stress testing to develop a dark environmental chamber in-situ measurement procedure for determining module power loss. From the analysis we determine three main categories of failure modes associated with the module degradation consisting of: shunting, recombination losses, increased series resistance losses, and current mismatch losses associated with a decrease in photo-current generation by removal of some cell areas due to cell fractures. Based on the analysis, we propose an in-situ module power loss monitoring procedure that relies on dark current-voltage measurements taken during the stress test, and initial and final module flash testing, to determine the power degradation characteristic of the module.

  8. Fundamental Research and Development for Improved Crystalline Silicon Solar Cells: Final Subcontract Report, March 2002 - July 2006

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, A.

    2007-11-01

    This report summarizes the progress made by Georgia Tech in the 2002-2006 period toward high-efficiency, low-cost crystalline silicon solar cells. This program emphasize fundamental and applied research on commercial substrates and manufacturable technologies. A combination of material characterization, device modeling, technology development, and complete cell fabrication were used to accomplish the goals of this program. This report is divided into five sections that summarize our work on i) PECVD SiN-induced defect passivation (Sections 1 and 2); ii) the effect of material inhomogeneity on the performance of mc-Si solar cells (Section 3); iii) a comparison of light-induced degradation in commercially grown Ga- and B-doped Czochralski Si ingots (Section 4); and iv) the understanding of the formation of high-quality thick-film Ag contacts on high sheet-resistance emitters (Section 5).

  9. In-Situ Measurement of Power Loss for Crystalline Silicon Modules Undergoing Thermal Cycling and Mechanical Loading Stress Testing: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Spataru, Sergiu; Hacke, Pater; Sera, Dezso

    2015-09-15

    We analyze the degradation of multi-crystalline silicon photovoltaic modules undergoing simultaneous thermal, mechanical, and humidity stress testing to develop a dark environmental chamber in-situ measurement procedure for determining module power loss. From the analysis we determine three main categories of failure modes associated with the module degradation consisting of: shunting, recombination losses, increased series resistance losses, and current mismatch losses associated with a decrease in photo-current generation by removal of some cell areas due to cell fractures. Based on the analysis, we propose an in-situ module power loss monitoring procedure that relies on dark current-voltage measurements taken during the stress test, and initial and final module flash testing, to determine the power degradation characteristic of the module.

  10. Mismatched front and back gratings for optimum light trapping in ultra-thin crystalline silicon solar cells

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan K.; Branham, Matthew S.; Huang, Yi; Yerci, Selçuk; Boriskina, Svetlana V.; Chen, Gang

    2016-10-01

    The implementation of a front and back grating in ultra-thin photovoltaic cells is a promising approach towards improving light trapping. A simple design rule was developed using the least common multiple (LCM) of the front and back grating periods. From this design rule, several optimal period combinations can be found, providing greater design flexibility for absorbers of indirect band gap materials. Using numerical simulations, the photo-generated current (Jph) for a 10-μm-thick crystalline silicon absorber was predicted to be as high as 38 mA/cm2, which is 11.74% higher than that of a single front grating (Jph=34 mA/cm2).

  11. Influence of the pattern shape on the photonic efficiency of front-side periodically patterned ultrathin crystalline silicon solar cells

    CERN Document Server

    Herman, Aline; Depauw, Valerie; Daif, Ounsi El; Deparis, Olivier

    2012-01-01

    Patterning the front side of an ultra-thin crystalline silicon (c Si) solar cell helps keeping the energy conversion efficiency high by compensating for the light absorption losses. A super-Gaussian mathematical expression was used in order to encompass a large variety of nanopattern shapes and to study their influence on the photonic performance. We prove that the enhancement in the maximum achievable photo-current is due to both impedance matching condition at short wavelengths and to the wave nature of light at longer wavelengths. We show that the optimal mathematical shape and parameters of the pattern depend on the c Si thickness. An optimal shape comes with a broad optimal parameter zone where fabricating errors would have much less influence on the efficiency. We prove that cylinders are not the best suited shape. To compare our model with a real slab, we fabricated a nanopatterned c Si slab via Nano Imprint Lithography.

  12. Characterization of transparent conductive oxide films and their effect on amorphous/crystalline silicon heterojunction solar cells

    Science.gov (United States)

    Meng, Fanying; Shi, Jianhua; Shen, Leilei; Zhang, Liping; Liu, Jinning; Liu, Yucheng; Yu, Jian; Bao, Jian; Liu, Zhengxin

    2017-04-01

    Three different dopant indium oxide thin films were fabricated at low temperatures by reactive plasma deposition and sputtering. The optical and electrical characteristics of these films were analyzed as a function of the Hall electron concentration. Furthermore, these films were applied to amorphous/crystalline silicon heterojunction solar cells as transparent electrodes. Consequently, it was demonstrated that the high Hall mobility, high refractive index, and low extinction coefficient of transparent conductive oxide (TCO) films contribute to the high product of short-circuit current density and fill factor and conversion efficiency. Furthermore, it was found that the solar cell with a finger spacing of 1.9 mm on a 125 × 125 mm2 Si wafer is highly tolerant to TCO film resistivity when the electron concentration is less than 4.0 × 1020 cm-3.

  13. Direct writing of continuous and discontinuous sub-wavelength periodic surface structures on single-crystalline silicon using femtosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Kuladeep, Rajamudili; Sahoo, Chakradhar; Narayana Rao, Desai, E-mail: dnrsp@uohyd.ernet.in, E-mail: dnr-laserlab@yahoo.com [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2014-06-02

    Laser-induced ripples or uniform arrays of continuous near sub-wavelength or discontinuous deep sub-wavelength structures are formed on single-crystalline silicon (Si) by femtosecond (fs) laser direct writing technique. Laser irradiation was performed on Si wafers at normal incidence in air and by immersing them in dimethyl sulfoxide using linearly polarized Ti:sapphire fs laser pulses of ∼110 fs pulse duration and ∼800 nm wavelength. Morphology studies of laser written surfaces reveal that sub-wavelength features are oriented perpendicular to laser polarization, while their morphology and spatial periodicity depend on the surrounding dielectric medium. The formation mechanism of the sub-wavelength features is explained by interference of incident laser with surface plasmon polaritons. This work proves the feasibility of fs laser direct writing technique for the fabrication of sub-wavelength features, which could help in fabrication of advanced electro-optic devices.

  14. Utilization of the sum rule for construction of advanced dispersion model of crystalline silicon containing interstitial oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Franta, Daniel, E-mail: franta@physics.muni.cz [Department of Physical Electronic, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno (Czech Republic); Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University Kamenice 5, 62500 Brno (Czech Republic); Nečas, David; Zajíčková, Lenka [Department of Physical Electronic, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno (Czech Republic); Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University Kamenice 5, 62500 Brno (Czech Republic); Ohlídal, Ivan [Department of Physical Electronic, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno (Czech Republic)

    2014-11-28

    The distribution of the total transition strength, i.e. the right hand side of the integral form of Thomas–Reiche–Kuhn sum rule, into individual absorption processes is described for crystalline silicon containing interstitial oxygen. Utilization of the sum rule allows the construction of a dispersion model covering all elementary excitations from phonon absorption to core electron excitations. The dependence of transition strength of individual electronic and phonon contributions on temperature and oxygen content is described. - Highlights: • Distribution of transition strength for c-Si containing interstitial oxygen • Temperature dependence of transition strength of individual contributions • Dependence of transition strength on concentration of interstitial oxygen • Consideration of interband electronic transitions, free carriers, and phonons.

  15. Comparison of slowness profiles of lamb wave with elastic moduli and crystal structure in single crystalline silicon wafers

    Energy Technology Data Exchange (ETDEWEB)

    Min, Young Jae; Yun, Gyeong Won; Kim, Kyung Min; Roh, Yuji; Kim, Young H. [Applied Acoustics Lab, Korea Science Academy of KAIST, Busan (Korea, Republic of)

    2016-02-15

    Single crystalline silicon wafers having (100), (110), and (111) directions are employed as specimens for obtaining slowness profiles. Leaky Lamb waves (LLW) from immersed wafers were detected by varying the incident angles of the specimens and rotating the specimens. From an analysis of LLW signals for different propagation directions and phase velocities of each specimen, slowness profiles were obtained, which showed a unique symmetry with different symmetric axes. Slowness profiles were compared with elastic moduli of each wafer. They showed the same symmetries as crystal structures. In addition, slowness profiles showed expected patterns and values that can be inferred from elastic moduli. This implies that slowness profiles can be used to examine crystal structures of anisotropic solids.

  16. Low-temperature grown indium oxide nanowire-based antireflection coatings for multi-crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu-Cian; Chen, Chih-Yao; Chen, I Chen [Institute of Materials Science and Engineering, National Central University, Taoyuan (China); Kuo, Cheng-Wen; Kuan, Ta-Ming; Yu, Cheng-Yeh [TSEC Corporation, Hsinchu (China)

    2016-08-15

    Light harvesting by indium oxide nanowires (InO NWs) as an antireflection layer on multi-crystalline silicon (mc-Si) solar cells has been investigated. The low-temperature growth of InO NWs was performed in electron cyclotron resonance (ECR) plasma with an O{sub 2}-Ar system using indium nanocrystals as seed particles via the self-catalyzed growth mechanism. The size-dependence of antireflection properties of InO NWs was studied. A considerable enhancement in short-circuit current (from 35.39 to 38.33 mA cm{sup -2}) without deterioration of other performance parameters is observed for mc-Si solar cells coated with InO NWs. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Improving Crystalline Silicon Solar Cell Efficiency Using Graded-Refractive-Index SiON/ZnO Nanostructures

    OpenAIRE

    Yung-Chun Tu; Shui-Jinn Wang; Chien-Hung Wu; Kow-Ming Chang; Tseng-Hsing Lin; Chien-Hsiung Hung; Jhen-Siang Wu

    2015-01-01

    The fabrication of silicon oxynitride (SiON)/ZnO nanotube (NT) arrays and their application in improving the energy conversion efficiency (η) of crystalline Si-based solar cells (SCs) are reported. The SiON/ZnO NT arrays have a graded-refractive-index that varies from 3.5 (Si) to 1.9~2.0 (Si3N4 and ZnO) to 1.72~1.75 (SiON) to 1 (air). Experimental results show that the use of 0.4 μm long ZnO NT arrays coated with a 150 nm thick SiON film increases Δη/η by 39.2% under AM 1.5 G (100 mW/cm2) ill...

  18. 16th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Program, Extended Abstracts, and Papers

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, B. L.

    2006-08-01

    The National Center for Photovoltaics sponsored the 16th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes held August 6-9, 2006 in Denver, Colorado. The workshop addressed the fundamental properties of PV-Si, new solar cell designs, and advanced solar cell processing techniques. It provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The Workshop Theme was: "Getting more (Watts) for Less ($i)". A combination of oral presentations by invited speakers, poster sessions, and discussion sessions reviewed recent advances in crystal growth, new cell structures, new processes and process characterization techniques, and cell fabrication approaches suitable for future manufacturing demands. The special sessions included: Feedstock Issues: Si Refining and Purification; Metal-impurity Engineering; Thin Film Si; and Diagnostic Techniques.

  19. Plasma etching on large-area mono-, multi- and quasi-mono crystalline silicon

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk; Boisen, Anja

    2013-01-01

    We use plasma etched Black Si (BS)[1][2] nanostructures to achieve low reflectance due to the resulting graded refractive index at the Si-air interface. The goal of this investigation is to develop a suitable texturing method for Si solar cells. Branz et al. [3]report below 3% average reflectance...... advantages such as; (i) excellent light trapping, (ii) dry, single-sided and scalable process method and (iii) etch independence on crystallinity of Si, RIE-texturing has so far not been proven superior to standard wet texturing, primarily as a result of lower power conversion efficiency due to increased...... using maskless RIE in a O2 and SF6 plasma, and the surface topology was optimized for solar cell applications by varying gas flows, pressure, power and process time. The starting substrates were 156x156 mm p-type, CZ mono-, multi- and quasi-mono crystalline Si wafers, respectively, with a thickness...

  20. Studying the Kinetics of Crystalline Silicon Nanoparticle Lithiation with In Situ Transmission Electron Microscopy

    KAUST Repository

    McDowell, Matthew T.

    2012-09-04

    In situ transmission electron microscopy (TEM) is used to study the electrochemical lithiation of high-capacity crystalline Si nanoparticles for use in Li-ion battery anodes. The lithiation reaction slows down as it progresses into the particle interior, and analysis suggests that this behavior is due not to diffusion limitation but instead to the influence of mechanical stress on the driving force for reaction. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Silicon Monoxide at 1 atm and Elevated Pressures: Crystalline or Amorphous?

    KAUST Repository

    AlKaabi, Khalid

    2014-03-05

    The absence of a crystalline SiO phase under ordinary conditions is an anomaly in the sequence of group 14 monoxides. We explore theoretically ordered ground-state and amorphous structures for SiO at P = 1 atm, and crystalline phases also at pressures up to 200 GPa. Several competitive ground-state P = 1 atm structures are found, perforce with Si-Si bonds, and possessing Si-O-Si bridges similar to those in silica (SiO2) polymorphs. The most stable of these static structures is enthalpically just a little more stable than a calculated random bond model of amorphous SiO. In that model we find no segregation into regions of amorphous Si and amorphous SiO2. The P = 1 atm structures are all semiconducting. As the pressure is increased, intriguing new crystalline structures evolve, incorporating Si triangular nets or strips and stishovite-like regions. A heat of formation of crystalline SiO is computed; it is found to be the most negative of all the group 14 monoxides. Yet, given the stability of SiO2, the disproportionation 2SiO (s) → Si(s)+SiO2(s) is exothermic, falling right into the series of group 14 monoxides, and ranging from a highly negative ΔH of disproportionation for CO to highly positive for PbO. There is no major change in the heat of disproportionation with pressure, i.e., no range of stability of SiO with respect to SiO2. The high-pressure SiO phases are metallic. © 2014 American Chemical Society.

  2. Plasma etching on large-area mono-, multi- and quasi-mono crystalline silicon

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk; Boisen, Anja

    2013-01-01

    We use plasma etched Black Si (BS)[1][2] nanostructures to achieve low reflectance due to the resulting graded refractive index at the Si-air interface. The goal of this investigation is to develop a suitable texturing method for Si solar cells. Branz et al. [3]report below 3% average reflectance...... for their 16.8% efficient black Si cell using a metal-assisted, chemical etching method on FZ mono-crystalline Si substrates. Yoo et al. [4] use RIE similar to this work on large-area, multi-crystalline Si cells and achieve a 16.1% efficiency despite a relatively high reflectance of 13.3%. Despite several...... advantages such as; (i) excellent light trapping, (ii) dry, single-sided and scalable process method and (iii) etch independence on crystallinity of Si, RIE-texturing has so far not been proven superior to standard wet texturing, primarily as a result of lower power conversion efficiency due to increased...

  3. 15th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Extended Abstracts and Papers

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, B. L.

    2005-11-01

    The National Center for Photovoltaics sponsored the 15th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, held in Vail, CO, August 7-10, 2005. This meeting provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The workshop addressed the fundamental properties of PV silicon, new solar cell designs, and advanced solar cell processing techniques. A combination of oral presentations by invited speakers, poster sessions, and discussion sessions reviewed recent advances in crystal growth, new cell designs, new processes and process characterization techniques, and cell fabrication approaches suitable for future manufacturing demands. The theme of this year's meeting was 'Providing the Scientific Basis for Industrial Success.' Specific sessions during the workshop included: Advances in crystal growth and material issues; Impurities and defects in Si; Advanced processing; High-efficiency Si solar cells; Thin Si solar cells; and Cell design for efficiency and reliability module operation. The topic for the Rump Session was ''Si Feedstock: The Show Stopper'' and featured a panel discussion by representatives from various PV companies.

  4. A fair comparison between ultrathin crystalline-silicon solar cells with either periodic or correlated disorder inverted pyramid textures.

    Science.gov (United States)

    Muller, Jérôme; Herman, Aline; Mayer, Alexandre; Deparis, Olivier

    2015-06-01

    Fabrication of competitive solar cells based on nano-textured ultrathin silicon technology is challenging nowadays. Attention is paid to the optimization of this type of texture, with a lot of simulation and experimental results published in the last few years. While previous studies discussed mainly the local features of the surface texture, we highlight here the importance of their filling fraction. In this work, we focus on a fair comparison between a technologically realizable correlated disorder pattern of inverted nano-pyramids on an ultrathin crystalline-silicon layer, and its periodically patterned counterpart. A fair comparison is made possible by defining an equivalent periodic structure for each hole filling fraction. Moreover, in order to be as realistic as possible, we consider patterns that could be fabricated by standard patterning techniques: hole-mask colloidal lithography, nanoimprint lithography and wet chemical etching. Based on numerical simulations, we show that inverted nano-pyramid patterns with correlated disorder provide typically greater efficiency than their periodic counterparts. However, the hole filling fraction of the etched pattern plays a crucial role and may limit the benefits of the correlated disorder due to experimental restrictions on pattern fabrication.

  5. Application and validation of algebraic methods to predict the behaviour of crystalline silicon PV modules in Mediterranean climates

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, M.; Nofuentes, G.; Aguilera, J.; Talavera, D.L. [Grupo de Investigacion IDEA, Escuela Politecnica Superior, Universidad de Jaen, Campus de Las Lagunillas, s/n, 23071-Jaen (Spain); Castro, M. [Electrical and Computer Engineering Department, UNED, Ciudad Universitaria, Juan del Rosal, 12, 28040-Madrid (Spain)

    2007-11-15

    Predicting both PV module and generator performances under natural sunlight is a key issue for designers and installers. Five simple algebraic methods addressed to predict this behaviour in Mediterranean climates have been empirically validated. Firstly, the calibration in STC of all significant electrical parameters of both a monocrystalline and a polycrystalline silicon PV modules was entrusted to an accredited independent laboratory. Then, a 12-month test and measurement campaign carried out on these modules in the city of Jaen (Spain, latitude 38 N, longitude 3 W) has provided the necessary experimental data. Results show that (a) crystalline silicon PV module outdoors performance may be described with sufficient accuracy - for PV engineering purposes - only taking into account incident global irradiance, cell temperature, and using any one of two simple algebraic methods tried in this paper and (b) regardless the used method, poor results may be achieved if the PV specimens under study are not electrically characterised in STC prior to analysing their outdoors performance. Even so, the methods recommended in (a) perform best. (author)

  6. CARBON DIOXIDE SEPARATION BY SELECTIVE PERMEATION.

    Science.gov (United States)

    CARBON DIOXIDE , SEPARATION), (*PERMEABILITY, CARBON DIOXIDE ), POROUS MATERIALS, SILICON COMPOUNDS, RUBBER, SELECTION, ADSORPTION, TEMPERATURE, PRESSURE, POLYMERS, FILMS, PLASTICS, MEMBRANES, HUMIDITY.

  7. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

    Science.gov (United States)

    He, Z.-H.; Beaurepaire, B.; Nees, J. A.; Gallé, G.; Scott, S. A.; Pérez, J. R. Sánchez; Lagally, M. G.; Krushelnick, K.; Thomas, A. G. R.; Faure, J.

    2016-11-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes.

  8. Sintering of nano crystalline silicon carbide by doping with boron carbide

    Indian Academy of Sciences (India)

    M S Datta; A K Bandyopadhyay; B Chaudhuri

    2002-06-01

    Sinterable nano silicon carbide powders of mean particle size (37 nm) were prepared by attrition milling and chemical processing of an acheson type alpha silicon carbide having mean particle size of 0.39 m (390 nm). Pressureless sintering of these powders was achieved by addition of boron carbide of 0.5 wt% together with carbon of 1 wt% at 2050°C at vacuum (3 mbar) for 15 min. Nearly 99% sintered density was obtained. The mechanism of sintering was studied by scanning electron microscopy and transmission electron microscopy. This study shows that the mechanism is a solid-state sintering process. Polytype transformation from 6H to 4H was observed.

  9. Crystalline silicon surface passivation by thermal ALD deposited Al doped ZnO thin films

    Directory of Open Access Journals (Sweden)

    Jagannath Panigrahi

    2017-03-01

    Full Text Available The evidence of good quality silicon surface passivation using thermal ALD deposited Al doped zinc oxide (AZO thin films is demonstrated. AZO films are prepared by introducing aluminium precursor in between zinc and oxygen precursors during the deposition. The formation of AZO is confirmed by ellipsometry, XRD and Hall measurements. Effective minority carrier lifetime (τeff greater than 1.5ms at intermediate bulk injection levels is realized for symmetrically passivated p-type silicon surfaces under optimised annealing conditions of temperature and time in hydrogen ambient. The best results are realised at 450°C annealing for >15min. Such a layer may lead to implied open circuit voltage gain of 80mV.

  10. Comparison of specific production performances by two crystalline silicon PV systems

    Directory of Open Access Journals (Sweden)

    Martin Fajman

    2013-01-01

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

  11. On the origin of inter band gap radiative emission in crystalline silicon

    Directory of Open Access Journals (Sweden)

    I. Burud

    2012-12-01

    Full Text Available Crystal imperfections degrade the quality of multicrystalline silicon wafers by introducing alternative recombination mechanisms. Here we use non-destructive hyperspectral imaging to detect photoluminescence signals from radiatively active recombination processes over the wafer with a highly resolved spectral third dimension. We demonstrate that band-to-band recombination can be visually separated from recombination through traps across the whole surface of a wafer using hyperspectral imaging. Our samples are studied in the near infrared wavelength region, 900-1700 nm, which includes the region of the so called D-band emission lines. These constitute four resolved emission lines found in the photoluminescence spectrum of silicon, commonly related to recombination through shallow inter-band gap energy levels near the conduction- and valence band edges. The shape and structure of these emissions from our measurements suggest that all the D-lines have different origins.

  12. Optimization of sodium carbonate texturization on large-area crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Marrero, N.; Gonzalez-Diaz, B.; Guerrero-Lemus, R.; Hernandez-Rodriguez, C. [Departamento de Fisica Basica, Universidad de La Laguna, Avda, Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Borchert, D. [Auf der Reihe 2, Institut fuer Solare Energiesysteme, Fraunhofer Institut, 45884 Gelsenkirchen (Germany)

    2007-12-14

    This work describes a texturization method for monocrystalline silicon solar cells based on a mixture of sodium carbonate and sodium hydrogen carbonate solutions. A specific solution has been found that results in an optimal etching rate, the lowest surface reflectance and a homogeneous density of pyramidal structures on the silicon surface. The subsequent phosphorus diffusion with rapid thermal processes has been modified in order to drastically reduce the process time and, simultaneously, to obtain a high homogeneity of the sheet resistance values and improved photocarriers lifetimes. 100 x 100 mm solar cells with an efficiency of 15.8% have been obtained compared to an efficiency of 14.7% for the reference cell. (author)

  13. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

    CERN Document Server

    He, Z -H; Nees, J A; Gallé, G; Scott, S A; Pérez, J R Sanchez; Lagally, M G; Krushelnick, K; Thomas, A G R; Faure, J

    2016-01-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-di...

  14. Structural defects caused by a rough substrate and their influence on the performance of hydrogenated nano-crystalline silicon n-i-p solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongbo B.T.; Franken, Ronald H.; Rath, Jatindra K.; Schropp, Ruud E.I. [Nanophotonics - Physics of Devices, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht (Netherlands)

    2009-03-15

    We present a cross-sectional transmission electron microscopy study of a set of hydrogenated nano-crystalline silicon n-i-p solar cells deposited by hot-wire chemical vapour deposition on Corning glass substrates coated with ZnO-covered Ag layers with various surface roughnesses. Strip-like structural defects (voids and low-density areas) are observed in the silicon layers originating from micro-valleys of Ag grains. A correlation between the opening angles of the textured surface and the appearance of these strips was found. We propose that in order to grow high-quality hydrogenated nano-crystalline silicon absorber layers for solar cell applications, the morphology of the Ag surface is a critical property, and the micro-valleys at the ZnO surface with an opening angle smaller than around 110 should be avoided. (author)

  15. Dislocation formation in seed crystals induced by feedstock indentation during growth of quasimono crystalline silicon ingots

    Science.gov (United States)

    Trempa, M.; Beier, M.; Reimann, C.; Roßhirth, K.; Friedrich, J.; Löbel, C.; Sylla, L.; Richter, T.

    2016-11-01

    In this work the dislocation formation in the seed crystal induced by feedstock indentation during the growth of quasimono (QM) silicon ingots for photovoltaic application was investigated. It could be shown by special laboratory indentation experiments that the formed dislocations propagate up to several millimeters deep into the volume of the seed crystal in dependence on the applied pressure of the feedstock particles on the surface of the seed crystal. Further, it was demonstrated that these dislocations if they were not back-melted during the seeding process grow further into the silicon ingot and drastically reduce its material quality. An estimation of the apparent pressure values in a G5 industrial crucible/feedstock setup reveals that the indentation phenomenon is a critical issue for the industrial production of QM silicon ingots. Therefore, some approaches to avoid/reduce the indentation events were tested with the result, that the most promising solution should be the usage of suitable feedstock particles as coverage of the seed.

  16. Self-diffusion in crystalline silicon: A single diffusion activation enthalpy down to 755°

    Science.gov (United States)

    Südkamp, Tobias; Bracht, Hartmut

    2016-09-01

    Self-diffusion in silicon and the contribution of vacancies and self-interstitials have been controversially discussed for 50 yr. Most recent results show that the intrinsic silicon self-diffusion coefficient deviates from an Arrhenius-type, single exponential function for temperatures below 950° [Y. Shimizu, M. Uematsu, and K. M. Itoh, Phys. Rev. Lett. 98, 095901 (2007), 10.1103/PhysRevLett.98.095901; R. Kube, H. Bracht, E. Hüger, H. Schmidt, J. L. Hansen, A. N. Larsen, J. W. Ager, E. E. Haller, T. Geue, and J. Stahn, Phys. Rev. B 88, 085206 (2013), 10.1103/PhysRevB.88.085206]. This led us to propose temperature-dependent thermodynamic properties of vacancies in order to achieve full consistency to vacancy-mediated dopant diffusion in silicon. Concepts of temperature-dependent properties of native defects or distinct forms of defects with different formation entropies suggested by Cowern et al. [N. E. B. Cowern, S. Simdyankin, C. Ahn, N. S. Bennett, J. P. Goss, J.-M. Hartmann, A. Pakfar, S. Hamm, J. Valentin, E. Napolitani, D. De Salvador, E. Bruno, and S. Mirabella, Phys. Rev. Lett. 110, 155501 (2013), 10.1103/PhysRevLett.110.155501] question the present understanding on atomic transport in semiconductors. To verify these concepts, additional self-diffusion experiments under particular gettering conditions were performed. As a result, silicon self-diffusion was found to be accurately described by one single diffusion activation enthalpy of (4.73 ±0.02 ) eV down to 755°C. This provides full consistency to dopant diffusion without claiming native-defect concepts that were originally proposed by Seeger and Chik in 1968 [A. Seeger and K. P. Chik, Phys. Stat. Sol. 29, 455 (1968), 10.1002/pssb.19680290202] and confirms most recent density functional theory calculations on the activation energy of self-diffusion via vacancies and self-interstitials. Overall, this unravels the old debate of self-diffusion in silicon with the supposed intrinsic temperature dependence.

  17. Dynamic Chemically Driven Dewetting, Spreading, and Self-Running of Sessile Droplets on Crystalline Silicon.

    Science.gov (United States)

    Arscott, Steve

    2016-12-06

    A chemically driven dewetting effect is demonstrated using sessile droplets of dilute hydrofluoric acid on chemically oxidized silicon wafers. The dewetting occurs as the thin oxide is slowly etched by the droplet and replaced by a hydrogen-terminated surface; the result of this is a gradual increase in the contact angle of the droplet with time. The time-varying work of adhesion is calculated from the time-varying contact angle; this corresponds to the changing chemical nature of the surface during dewetting and can be modeled by the well-known logistic (sigmoid) function often used for the modeling of restricted growth, in this case, the transition from an oxidized surface to a hydrogen-terminated silicon surface. The observation of the time-varying contact angle allows one to both measure the etch rate of the silicon oxide and estimate the hydrogenation rate as a function of HF concentration and wafer type. In addition to this, at a certain HF concentration, a self-running droplet effect is observed. In contrast, on hydrogen-terminated silicon wafers, a chemically induced spreading effect is observed using sessile droplets of nitric acid. The droplet spreading can also be modeled using a logistical function, where the restricted growth is the transition from hydrogen-terminated to a chemically induced oxidized silicon surface. The chemically driven dewetting and spreading observed here add to the methods available to study dynamic wetting (e.g., the moving three-phase contact line) of sessile droplets on surfaces. By slowing down chemical kinetics of the wetting, one is able to record the changing profile of the sessile droplet with time and gather information concerning the time-varying surface chemistry. The data also indicates a chemical interface hysteresis (CIH) that is compared to contact angle hysteresis (CAH). The approach can also be used to study the chemical etching and deposition behavior of thin films using liquids by monitoring the macroscopic

  18. Soil microbial community responses to contamination with silver, aluminium oxide and silicon dioxide nanoparticles.

    Science.gov (United States)

    McGee, C F; Storey, S; Clipson, N; Doyle, E

    2017-04-01

    Soil microorganisms are key contributors to nutrient cycling and are essential for the maintenance of healthy soils and sustainable agriculture. Although the antimicrobial effects of a broad range of nanoparticulate substances have been characterised in vitro, little is known about the impact of these compounds on microbial communities in environments such as soil. In this study, the effect of three widely used nanoparticulates (silver, silicon dioxide and aluminium oxide) on bacterial and fungal communities in an agricultural pastureland soil was examined in a microcosm-based experiment using a combination of enzyme analysis, molecular fingerprinting and amplicon sequencing. A relatively low concentration of silver nanoparticles (AgNPs) significantly reduced total soil dehydrogenase and urease activity, while Al2O3 and SiO2 nanoparticles had no effect. Amplicon sequencing revealed substantial shifts in bacterial community composition in soils amended with AgNPs, with significant decreases in the relative abundance of Acidobacteria and Verrucomicrobia and an increase in Proteobacteria. In particular, the relative abundance of the Proteobacterial genus Dyella significantly increased in AgNP amended soil. The effects of Al2O3 and SiO2 NPs on bacterial community composition were less pronounced. AgNPs significantly reduced bacterial and archaeal amoA gene abundance in soil, with the archaea more susceptible than bacteria. AgNPs also significantly impacted soil fungal community structure, while Al2O3 and SiO2 NPs had no effect. Several fungal ribotypes increased in soil amended with AgNPs, compared to control soil. This study highlights the need to consider the effects of individual nanoparticles on soil microbial communities when assessing their environmental impact.

  19. A novel enzymatic microreactor with Aspergillus oryzae β-galactosidase immobilized on silicon dioxide nanosprings.

    Science.gov (United States)

    Schilke, Karl F; Wilson, Kelly L; Cantrell, Timothy; Corti, Giancarlo; McIlroy, David N; Kelly, Christine

    2010-01-01

    The use of silicon dioxide (SiO(2) ) nanosprings as supports for immobilized enzymes in a continuous microreactor is described. A nanospring mat (2.2 cm(2) × 60 μm thick) was functionalized with γ-aminopropyltriethoxysilane, then treated with N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP) and dithiothreitol (DTT) to produce surface thiol (--SH) groups. SPDP-modified β-galactosidase from Aspergillus oryzae was immobilized on the thiolated nanosprings by reversible disulfide linkages. The enzyme-coated nanospring mat was placed into a 175-μm high microchannel, with the mat partially occluding the channel. The kinetics and steady-state conversion of hydrolysis of o-nitrophenyl β-D-galactosylpyranoside at various substrate flow rates and concentrations were measured. Substantial flow was observed through the nanosprings, for which the Darcy permeability κ ≈ 3 × 10(-6) cm(2) . A simple, one-parameter numerical model coupling Navier-Stokes and Darcy flow with a pseudo-first-order reaction was used to fit the experimental data. Simulated reactor performance was sensitive to changes in κ and the height of the nanospring mat. Permeabilities lower than 10(-8) cm(2) practically eliminated convective flow through the nanosprings, and substantially decreased conversion. Increasing the height of the mat increased conversion in simulations, but requires more enzymes and could cause sealing issues if grown above channel walls. Preliminary results indicate that in situ regeneration by reduction with DTT and incubation with SPDP-modified β-galactosidase is possible. Nanosprings provide high solvent-accessible surface area with good permeability and mechanical stability, can be patterned into existing microdevices, and are amenable to immobilization of biomolecules. Nanosprings offer a novel and useful support for enzymatic microreactors, biosensors, and lab-on-chip devices.

  20. Silicon Dioxide Impedes Antiviral Response and Causes Genotoxic Insult During Calicivirus Replication.

    Science.gov (United States)

    Agnihothram, Sudhakar S; Vermudez, Sheryl Anne; Mullis, Lisa; Townsend, Todd A; Manjanatha, Mugimane G; Azevedo, Marli P

    2016-07-01

    Noroviruses (NoV) are the leading cause of nonbacterial gastroenteritis in humans, and replicate extensively in the human gastrointestinal (GI) tract. Silica (also known as silicon dioxide, SiO2) nanoparticles (NPs) used in processed foods, dairy products, and beverages also accumulate in the GI tract. We investigated the effect of silica NPs on NoV replication and host cell response during virus infection, using murine norovirus (MNV-1) infection of RAW 264.7 murine macrophages. Pretreatment with 10 μg/ml silica significantly reduced the viability of macrophages, but no cumulative effects on viability of macrophages were observed with MNV-1 infection. No difference was observed between exposure to control or silica NPs on either the quantity of viral genome copies or the production of infectious virus in macrophages infected with MNV-1. Silica NPs reduced the ability of macrophages to upregulate genes encoding bone morphogenic proteins (BMPs), chemokine ligands and cytokines for which expression levels were otherwise found to be upregulated in response to MNV-1 infection. Furthermore, silica NPs reduced the levels of proinflammatory cytokines secreted by macrophages in response to MNV infection. Finally, silica NPs with MNV-1 infection produced a genotoxic insult to macrophages. Strikingly, this genotoxic insult was also found to occur as a synergistic effect of silica NPs and feline calicivirus infection in feline kidney epithelial cells. Taken together, our study suggests important safety considerations related to reducing exposure to silica NPs affecting the GI tract in individuals infected with NoVs and possibly other foodborne viruses.

  1. Photochemical reactions of brominated diphenylethers in organic solvents and adsorbed on silicon dioxide in aqueous suspension

    Energy Technology Data Exchange (ETDEWEB)

    Palm, W.U.; Kopetzky, R.; Sossinka, W.; Ruck, W. [Univ. of Lueneburg, Environmental Chemistry, Lueneburg (Germany); Zetzsch, C. [Univ. of Bayreuth, Atmos. Chem. Research, Bayreuth, and Fraunhofer-Inst. of Toxicology and Experimental Medicine, Hannover (Germany)

    2004-09-15

    Polybrominated diphenylethers (BDEs) are in use as flame retardants worldwide and are found as xenobiotics in environmental samples. Photolysis by sunlight, one of the potential abiotic degradation pathways, is found to be rapid in laboratory experiments, especially for deca-BDE, the most prominent BDE as compared to commercial penta- and octa-BDEs. Due to the extremely low water solubility of BDEs, these experiments were mostly performed in organic solvents so far, and a few in environmental matrices (sand and soil) and on dry and hydrated quartz glass. However, detailed UV absorption spectra of deca-BDE and debrominated BDEs in the relevant wavelength range above 300 nm have become available only recently, besides the UV maxima of a number of synthesized congeners at shorter wavelengths and an exploratory study from our laboratory. Other important parameters to assess the abiotic degradation in the environment, such as OH-rate constants and photolytic quantum yields of BDEs are not available. Furthermore, analysis of BDEs was mostly performed by GC-MS, and the capability of HPLC with a diode array detector (DAD) has not yet been exploited. This study presents kinetic results on the photolysis of BDEs in tetrahydrofuran (THF) with detailed photolytic pathways for a tetra-BDE (2,2'4,4'-BDE), a hexa-BDE (2,2'4,4',5,5'-BDE) and deca-BDE. Employing HPLC with a diode array detector (DAD) as analytical tool, quantum yields of BDEs with N{sub Br} = 1-10 are determined. Furthermore, the formation of brominated dibenzofurans (BDFs) was investigated. Since the environmental relevance of photolysis experiments in organic solvents is questionable, first results on photolysis of deca-BDE adsorbed on silicon dioxide particles, suspended in water, are presented.

  2. Heterointegration of III-V on silicon using a crystalline oxide buffer layer

    Science.gov (United States)

    Bhatnagar, K.; Rojas-Ramirez, J. S.; Contreras-Guerrero, R.; Caro, M.; Droopad, R.

    2015-09-01

    The integration of III-V compound semiconductors with Si can combine the cost advantage and maturity of Si technology with the superior performance of III-V materials. We have achieved the heteroepitaxial growth of III-V compound semiconductors on a crystalline SrTiO3 buffer layer grown on Si(0 0 1) substrates. A two-step growth process utilizing a high temperature nucleation layer of GaAs, followed by a low-temperature GaAs layer at a higher growth rate was employed to achieve highly crystalline thick GaAs layers on the SrTiO3/Si substrates with low surface roughness as seen by AFM. The effect of the GaAs nucleation layer on different surface terminations for the SrTiO3 layer was studied for both on axis and miscut wafers, which led to the conclusion that the Sr terminated surface on miscut substrates provides the best GaAs films. Using GaAs/STO/Si as virtual substrates, we have optimized the growth of high quality GaSb using the interfacial misfit (IMF) dislocation array technique. This work can lead to the possibility of realizing infrared detectors and next-generation high mobility III-V CMOS within the existing Si substrate infrastructure.

  3. High-temperature CVD for crystalline-silicon thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Faller, F.R.; Hurrle, A.

    1999-10-01

    The fundamentals of thermal CVD for the deposition of silicon at high temperatures are briefly discussed and applied to the conditions in the CVD system that the authors have constructed and characterized. The system fulfills basic requirements to be met for solar cell application; solar cells made from epitaxial layers on various substrates were fabricated. The high-quality cells achieved 17.6% efficiency proving the excellent performance of the system, the cells on economically relevant substrates achieved 8% efficiency which still needs improvement.

  4. Defects left after regrowth of amorphous silicon on crystalline Si : C (V) and DLTS studies

    OpenAIRE

    Castaing, J.; Cass, T.

    1985-01-01

    n and p-type silicon have been self-ion implanted at 77 K with multi-energetic beams. This process was used to amorphize a 0.4 μm layer with a minimum amount of damage in the underlying crystal. After regrowth by a 550 °C anneal, the remaining defects were assessed by capacitance-voltage (C(V )) measurements and deep level transient spectroscopy (DLTS). In n-type Si, a buried layer of deep donors in large concentration was found, whereas in p-type Si, their concentration was small. These trap...

  5. Mechanical grooving effect on the gettering efficiency of crystalline silicon based solar cells

    Science.gov (United States)

    Zarroug, Ahmed; Hamed, Zied Ben; Derbali, Lotfi; Ezzaouia, Hatem

    2017-04-01

    This paper examines a gettering process of Czochralski silicon (CZ) via mechanical texture, followed by two step heat treatment in the presence of porous silicon layer (PSL) under oxygen flow gas. It is shown that a process with PS has a positive trend of improvement in the electronic quality, and found to be more efficient when used in combination with mechanical grooving. We obtained a significant increase of the effective minority carrier lifetime and majority charge carriers mobility. Thus, there is an apparent decrease in the resistivity. These parameters were estimated through a The Quasi-Steady-State Photo-Conductance technique (QSSPC), the van Der Pauw method and Hall Effect. Particularly, we have made obvious that the large enhancement of the electronic quality of the wafers can be related to the presence of grooves, the influence during which the gettering process is of importance to overcome the unexpected saturation phenomena. The current voltage I-V characteristics of all samples had been measured under illumination. They were shown to enhance the photovoltaic properties of solar cells.

  6. Comparison of Photoluminescence Imaging on Starting Multi-Crystalline Silicon Wafers to Finished Cell Performance: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, S.; Yan, F.; Dorn, D.; Zaunbrecher, K.; Al-Jassim, M.; Sidelkheir, O.; Ounadjela, K.

    2012-06-01

    Photoluminescence (PL) imaging techniques can be applied to multicrystalline silicon wafers throughout the manufacturing process. Both band-to-band PL and defect-band emissions, which are longer-wavelength emissions from sub-bandgap transitions, are used to characterize wafer quality and defect content on starting multicrystalline silicon wafers and neighboring wafers processed at each step through completion of finished cells. Both PL imaging techniques spatially highlight defect regions that represent dislocations and defect clusters. The relative intensities of these imaged defect regions change with processing. Band-to-band PL on wafers in the later steps of processing shows good correlation to cell quality and performance. The defect band images show regions that change relative intensity through processing, and better correlation to cell efficiency and reverse-bias breakdown is more evident at the starting wafer stage as opposed to later process steps. We show that thermal processing in the 200 degrees - 400 degrees C range causes impurities to diffuse to different defect regions, changing their relative defect band emissions.

  7. A quantitative strain analysis of a flexible single-crystalline silicon membrane

    Science.gov (United States)

    Bong, Jae Hoon; Kim, Cheolgyu; Hwang, Wan Sik; Kim, Taek-Soo; Cho, Byung Jin

    2017-01-01

    This study presents a quantitative strain analysis of a single-crystal Si membrane for high performance flexible devices. Advanced thinning and transfer methods were used to make flexible single-crystal Si devices. Two Si membrane strain gauges, each with a different stack, were fabricated on a polydimethylsiloxane/polyimide film using a silicon-on-insulator wafer. One gauge contains a 10-μm-thick handling Si layer, whereas the handling Si layer was completely removed for the other case. Although the Si membrane with the 10-μm-thick handling Si layer is flexible, the strain applied to the active Si layer (0.127%) is three times higher than the strain applied to the Si membrane without the handling Si layer (0.037%) at a bending radius of 5 mm. This leads to the more reliable electrical and mechanical performance of the device fabricated on the Si membrane without the handling Si layer. The experimental results were verified through a finite element method simulation and analytical modeling. The quantitative strain analyses for flexible devices suggested here can expedite the realization of high performance flexible electronics using a single crystal silicon active layer.

  8. Crack Detection in Single-Crystalline Silicon Wafer Using Laser Generated Lamb Wave

    Directory of Open Access Journals (Sweden)

    Min-Kyoo Song

    2013-01-01

    Full Text Available In the semiconductor industry, with increasing requirements for high performance, high capacity, high reliability, and compact components, the crack has been one of the most critical issues in accordance with the growing requirement of the wafer-thinning in recent years. Previous researchers presented the crack detection on the silicon wafers with the air-coupled ultrasonic method successfully. However, the high impedance mismatching will be the problem in the industrial field. In this paper, in order to detect the crack, we propose a laser generated Lamb wave method which is not only noncontact, but also reliable for the measurement. The laser-ultrasonic generator and the laser-interferometer are used as a transmitter and a receiver, respectively. We firstly verified the identification of S0 and A0 lamb wave modes and then conducted the crack detection under the thermoelastic regime. The experimental results showed that S0 and A0 modes of lamb wave were clearly generated and detected, and in the case of the crack detection, the estimated crack size by 6 dB drop method was almost equal to the actual crack size. So, the proposed method is expected to make it possible to detect the crack in the silicon wafer in the industrial fields.

  9. What Is the Actual Local Crystalline Structure of Uranium Dioxide, UO2? A New Perspective for the Most Used Nuclear Fuel.

    Science.gov (United States)

    Desgranges, L; Ma, Y; Garcia, Ph; Baldinozzi, G; Siméone, D; Fischer, H E

    2017-01-03

    Up to now, uranium dioxide, the most used nuclear fuel, was said to have a Fm3̅m crystalline structure from 30 to 3000 K, and its behavior was modeled under this assumption. However, recently X-ray diffraction experiments provided atomic pair-distribution functions of UO2, in which UO distance was shorter than the expected value for the Fm3̅m space group. Here we show neutron diffraction results that confirm this shorter UO bond, and we also modeled the corresponding pair-distribution function showing that UO2 has a local Pa3̅ symmetry. The existence of a local lower symmetry in UO2 could explain some unexpected properties of UO2 that would justify UO2 modeling to be reassessed. It also deserves more study from an academic point of view because of its good thermoelectric properties that may originate from its particular crystalline structure.

  10. The potential for the fabrication of wires embedded in the crystalline silicon substrate using the solid phase segregation of gold in crystallising amorphous volumes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, A.C.Y.; McCallum, J.C

    2004-05-15

    The refinement of gold in crystallising amorphous silicon volumes was tested as a means of creating a conducting element embedded in the crystalline matrix. Amorphous silicon volumes were created by self-ion-implantation through a mask. Five hundred kiloelectronvolt Au{sup +} was then implanted into the volumes. The amorphous volumes were crystallised on a hot stage in air, and the crystallisation was characterised using cross sectional transmission electron microscopy. It was found that the amorphous silicon volumes crystallised via solid phase epitaxy at all the lateral and vertical interfaces. The interplay of the effects of the gold and also the hydrogen that infilitrated from the surface oxide resulted in a plug of amorphous material at the surface. Further annealing at this temperature demonstrated that the gold, once it had reached a certain critical concentration nucleated poly-crystalline growth instead of solid phase epitaxy. Time resolved reflectivity and Rutherford backscattering and channeling measurements were performed on large area samples that had been subject to the same implantation regime to investigate this system further. It was discovered that the crystallisation dynamics and zone refinement of the gold were complicated functions of both gold concentration and temperature. These findings do not encourage the use of this method to obtain conducting elements embedded in the crystalline silicon substrate.

  11. Semiconductor-metal phase transition of vanadium dioxide nanostructures on silicon substrate: Applications for thermal control of spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Leahu, G. L., E-mail: roberto.livoti@uniroma1.it; Li Voti, R., E-mail: roberto.livoti@uniroma1.it; Larciprete, M. C., E-mail: roberto.livoti@uniroma1.it; Belardini, A., E-mail: roberto.livoti@uniroma1.it; Mura, F., E-mail: roberto.livoti@uniroma1.it; Sibilia, C.; Bertolotti, M. [Dipartimento di Scienze di Base ed Applicate per l' Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16 00161 Roma (Italy); Fratoddi, I. [Dipartimento di Chimica, Sapienza Università di Roma, Piazzale A. Moro, Roma (Italy)

    2014-06-19

    We present a detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO2) film deposited on silicon wafer. The VO2 phase transition is studied in the mid-infrared (MIR) region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The temperature behaviour of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in VO2 which has been explained by applying the Maxwell Garnett effective medium approximation theory, together with a strong hysteresis phenomenon, both useful to design tunable thermal devices to be applied for the thermal control of spacecraft. We have also applied the photothermal radiometry in order to study the changes in the modulated emissivity induced by laser. Experimental results show how the use of these techniques represent a good tool for a quantitative measurement of the optothermal properties of vanadium dioxide based structures.

  12. Crystalline silicon for thin film solar cells. Final report; Kristallines Silizium fuer Duennschichtsolarzellen. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, H.

    2001-07-01

    Thin film solar cells based on silicon are of great interest for cost-effective conversion of solar energy into electric power. In order to reach this goal, intensive research is still necessary, pointing, e.g., to a further enhancement of the conversion efficiency, an improvement of stability and a reduction of the production time. Aim of the project work was the achievement of knowledge on microcrystalline silicon and its application in thin film solar cells by means of a broad research and development program. Material research focused on growth processes of the microcrystalline material, the incorporation and stability of hydrogen, the electronic transport and defects. In particular the transition from amorphous to microcrystalline material which is obtained for the present deposition methods by minor variations of the deposition parameters as well as the enhancement of the deposition rate were intensively studies. Another focus of research aimed toward the development and improvement of zinc oxide films which are of central importance for this type of solar cells for the application as transparent contacts. A comprehensive understanding was achieved. The films were incorporated in thin film solar cells and with conversion efficiencies >8% for single cells (at relatively high deposition rate) and 10% (stable) for tandem cells with amorphous silicon, top values were achieved by international standards. The project achievements serve as a base for a further development of this type of solar cell and for the transfer of this technology to industry. (orig.) [German] Duennschichtsolarzellen auf der Basis von Silizium sind von grossem Interesse fuer eine kostenguenstige Umwandlung von Sonnenenergie in elektrischen Strom. Um dieses Ziel zu erreichen, ist jedoch noch intensive Forschung, u.a. zur weiteren Steigerung des Wirkungsgrades, zur Verbesserung der Stabilitaet und zur Verkuerzung des Produktionsprozesses erforderlich. Ziel der Projektarbeiten war, durch ein

  13. Chemical Analysis Methods for Silicon Carbide

    Institute of Scientific and Technical Information of China (English)

    Shen Keyin

    2006-01-01

    @@ 1 General and Scope This Standard specifies the determination method of silicon dioxide, free silicon, free carbon, total carbon, silicon carbide, ferric sesquioxide in silicon carbide abrasive material.

  14. Synthesis, structure and photoelectrochemical properties of single crystalline silicon nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Dalchiele, E.A., E-mail: dalchiel@fing.edu.u [Instituto de Fisica, Facultad de Ingenieria, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay); Martin, F.; Leinen, D. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Departamentos de Fisica Aplicada and Ingenieria Quimica, Universidad de Malaga, Campus de Teatinos s/n, E29071 Malaga (Spain); Marotti, R.E. [Instituto de Fisica, Facultad de Ingenieria, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay); Ramos-Barrado, J.R. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Departamentos de Fisica Aplicada and Ingenieria Quimica, Universidad de Malaga, Campus de Teatinos s/n, E29071 Malaga (Spain)

    2010-01-31

    In the present work, n-type silicon nanowire (n-SiNW) arrays have been synthesized by self-assembly electroless metal deposition (EMD) nanoelectrochemistry. The synthesized n-SiNW arrays have been submitted to scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and optical studies. Initial probes of the solar device conversion properties and the photovoltaic parameters such as short-circuit current, open-circuit potential, and fill factor of the n-SiNW arrays have been explored using a liquid-junction in a photoelectrochemical (PEC) system under white light. Moreover, a direct comparison between the PEC performance of a polished n-Si(100) and the synthesized n-SiNW array photoelectrodes has been done. The PEC performance was significantly enhanced on the n-SiNWs photoelectrodes compared with that on polished n-Si(100).

  15. Eighth workshop on crystalline silicon solar cell materials and processes: Extended abstracts and papers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-08-01

    The theme of this workshop is Supporting the Transition to World Class Manufacturing. This workshop provides a forum for an informal exchange of information between researchers in the photovoltaic and non-photovoltaic fields on various aspects of impurities and defects in silicon, their dynamics during device processing, and their application in defect engineering. This interaction helps establish a knowledge base that can be used for improving device fabrication processes to enhance solar-cell performance and reduce cell costs. It also provides an excellent opportunity for researchers from industry and universities to recognize mutual needs for future joint research. The workshop format features invited review presentations, panel discussions, and two poster sessions. The poster sessions create an opportunity for both university and industrial researchers to present their latest results and provide a natural forum for extended discussions and technical exchanges.

  16. Influence of the impurity-defect and impurity-impurity interactions on the crystalline silicon solar cells conversion efficiency; Influence des interactions impurete-defaut et impurete-impurete sur le rendement de conversion des cellules photovoltaiques au silicium cristallin

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, S

    2007-05-15

    This study aims at understanding the influence of the impurity - defect interaction on the silicon solar cell performances. We studied first the case of single-crystalline silicon. We combined numerical simulations and experimental data providing new knowledge concerning metal impurities in silicon, to quantify the evolution of the conversion efficiency with the impurity concentration. Mainly due to the gettering effects, iron appears to be quite well tolerated. It is not the case for gold, diffusing too slowly. Hydrogenation effects were limited. We transposed then this study toward multi-crystalline silicon. Iron seems rather well tolerated, due to the gettering effects but also due to the efficiency of the hydrogenation. When slow diffusers are present, multi crystalline silicon is sensitive to thermal degradation. n-type silicon could solve this problem, this material being less sensitive to metal impurities. (author)

  17. A Monolithically Integrated Gallium Nitride Nanowire/Silicon Solar Cell Photocathode for Selective Carbon Dioxide Reduction to Methane.

    Science.gov (United States)

    Wang, Yichen; Fan, Shizhao; AlOtaibi, Bandar; Wang, Yongjie; Li, Lu; Mi, Zetian

    2016-06-20

    A gallium nitride nanowire/silicon solar cell photocathode for the photoreduction of carbon dioxide (CO2 ) is demonstrated. Such a monolithically integrated nanowire/solar cell photocathode offers several unique advantages, including the absorption of a large part of the solar spectrum and highly efficient carrier extraction. With the incorporation of copper as the co-catalyst, the devices exhibit a Faradaic efficiency of about 19 % for the 8e(-) photoreduction to CH4 at -1.4 V vs Ag/AgCl, a value that is more than thirty times higher than that for the 2e(-) reduced CO (ca. 0.6 %).

  18. Optical characterization of double-side-textured silicon wafer based on photonic nanostructures for thin-wafer crystalline silicon solar cells

    Science.gov (United States)

    Tayagaki, Takeshi; Furuta, Daichi; Aonuma, Osamu; Takahashi, Isao; Hoshi, Yusuke; Kurokawa, Yasuyoshi; Usami, Noritaka

    2017-04-01

    Crystalline silicon (c-Si) wafers have found extensive use in photovoltaic applications. In this regard, to enable advanced light manipulation in thin-wafer c-Si solar cells, we demonstrate the fabrication of double-side-textured Si wafers composed of a front-surface photonic nanotexture fabricated with quantum dot arrays and a rear-surface microtexture. The addition of the rear-surface microtexture to a Si wafer with the front-surface photonic nanotexture increases the wafer’s optical absorption in the near-infrared region, thus enabling enhanced light trapping. Excitation spectroscopy reveals that the photoluminescence intensity in the Si wafer with the double-sided texture is higher than that in the Si wafer without the rear-surface microtexture, thus indicating an increase in true optical absorption in the Si wafer with the double-sided texture. Our results indicate that the double-sided textures, i.e., the front-surface photonic nanotexture and rear-surface microtexture, can effectively reduce the surface reflection loss and provide enhanced light trapping, respectively.

  19. Random Si nanopillars for broadband antireflection in crystalline silicon solar cells

    Science.gov (United States)

    Choi, Junhee; Lee, Taek Sung; Jeong, Doo Seok; Lee, Wook Seong; Kim, Won Mok; Lee, Kyeong-Seok; Kim, Donghwan; Kim, Inho

    2016-09-01

    We demonstrate the fabrication of shallow Si nanopillar structures at a submicron scale which provides broadband antireflection for crystalline Si (c-Si) solar cells in the wavelength range of 350 nm-1100 nm. The Si random nanopillars were made by reactive ion etch (RIE) processing with thermally dewetted Sn metals as an etch mask. The diameters and coverages of the Si nanopillars were adjusted in a wide range of the nanoscale to microscale by varying the nominal thickness of the Sn metals and subsequent annealing temperatures. The height of the nanopillars was controlled by the RIE process time. The optimal size of the nanopillars, which are 340 nm in diameter and 150 nm in height, leads to the lowest average reflectance of 3.6%. We showed that the power conversion efficiency of the c-Si solar cells could be enhanced with the incorporation of optimally designed Si random nanopillars from 13.3% to 14.0%. The fabrication scheme of the Si nanostructures we propose in this study would be a cost-effective and promising light trapping technique for efficient c-Si solar cells.

  20. Organic nanowire/crystalline silicon p-n heterojunctions for high-sensitivity, broadband photodetectors.

    Science.gov (United States)

    Deng, Wei; Jie, Jiansheng; Shang, Qixun; Wang, Jincheng; Zhang, Xiujuan; Yao, Shenwen; Zhang, Qing; Zhang, Xiaohong

    2015-01-28

    Organic/inorganic hybrid devices are promising candidates for high-performance, low-cost optoelectronic devices, by virtue of their unique properties. Polycrystalline/amorphous organic films are widely used in hybrid devices, because defects in the films hamper the improvement of device performance. Here, we report the construction of 2,4-bis[4-(N,N-dimethylamino)phenyl]squaraine (SQ) nanowire (NW)/crystalline Si (c-Si) p-n heterojunctions. Thanks to the high crystal quality of the SQ NWs, the heterojunctions exhibit excellent diode characteristics in darkness. It is significant that the heterojunctions have been found to be capable of detecting broadband light with wavelengths spanning from ultraviolet (UV) light, to visible (Vis) light, to near-infrared (NIR) light, because of the complementary spectrum absorption of SQ NWs with Si. The junction is demonstrated to play a core role in enhancing the device performance, in terms of ultrahigh sensitivity, excellent stability, and fast response. The photovoltaic characteristics of the heterojunctions are further investigated, revealing a power conversion efficiency (PCE) of up to 1.17%. This result also proves the potential of the device as self-powered photodetectors operating at zero external bias voltage. This work presents an important advance in constructing single-crystal organic nanostructure/inorganic heterojunctions and will enable future exploration of their applications in broadband photodetectors and solar cells.

  1. Effective interface state effects in hydrogenated amorphous-crystalline silicon heterostructures using ultraviolet laser photocarrier radiometry

    Science.gov (United States)

    Melnikov, A.; Mandelis, A.; Halliop, B.; Kherani, N. P.

    2013-12-01

    Ultraviolet photocarrier radiometry (UV-PCR) was used for the characterization of thin-film (nanolayer) intrinsic hydrogenated amorphous silicon (i-a-Si:H) on c-Si. The small absorption depth (approximately 10 nm at 355 nm laser excitation) leads to strong influence of the nanolayer parameters on the propagation and recombination of the photocarrier density wave (CDW) within the layer and the substrate. A theoretical PCR model including the presence of effective interface carrier traps was developed and used to evaluate the transport parameters of the substrate c-Si as well as those of the i-a-Si:H nanolayer. Unlike conventional optoelectronic characterization methods such as photoconductance, photovoltage, and photoluminescence, UV-PCR can be applied to more complete quantitative characterization of a-Si:H/c-Si heterojunction solar cells, including transport properties and defect structures. The quantitative results elucidate the strong effect of a front-surface passivating nanolayer on the transport properties of the entire structure as the result of effective a-Si:H/c-Si interface trap neutralization through occupation. A further dramatic improvement of those properties with the addition of a back-surface passivating nanolayer is observed and interpreted as the result of the interaction of the increased excess bulk CDW with, and more complete occupation and neutralization of, effective front interface traps.

  2. Copper conducting electrode with nickel as a seed layer for selective emitter crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Atteq ur; Shin, Eun Gu; Lee, Soo Hong [Sejong University, Seoul (Korea, Republic of)

    2014-09-15

    In this research, we investigated selective emitter formation with a single-step photolithography process having a metallization scheme composed of nickel/copper metal stacks. The nickel seed layers were deposited by applying the electroless deposition process while copper was formed by light induced electro-plating arrangements as the main conducting electrode. The electroless deposition of nickel, along with a sintering process, was employed to create a diffusion barrier between copper and silicon. The nickel metal stack below the copper-conducting electrode also helped in lowering the sheet resistance and improving the contact adhesion. The nickel used as a seed layer was successfully demonstrated in the fabrication of a homogeneous 60 Ω/ emitter and selective emitter cells. Lower series resistances of 0.165 Ω and 0.253 Ω were achieved for the selective emitter and the homogeneous emitter cells, respectively. The best cell efficiency of 18.37% for the selective emitter solar cell was achieved, with average cell efficiencies of 18.17% and 17.3% for the selective emitter and the homogeneous emitter cells, respectively. An approximate efficiency increase of about 0.8% was recorded for the selective emitter solar cells.

  3. Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules.

    Science.gov (United States)

    Dias, Pablo; Javimczik, Selene; Benevit, Mariana; Veit, Hugo

    2017-02-01

    Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes its recycling meaningful economically and environmentally. In general, the recycling of PV modules starts with the removal of the polymeric ethylene-vinyl acetate (EVA) resin using pyrolysis, which assists in the recovery of materials such as silicon, copper and silver. The pyrolysis implementation, however, needs improvement given its importance. In this study, the polymers in the PV modules were characterized by Fourier transform infrared spectroscopy (FTIR) and the removal of the EVA resin using pyrolysis has been studied and optimized. The results revealed that 30min pyrolysis at 500°C removes >99% of the polymers present in photovoltaic modules. Moreover, the behavior of different particle size milled modules during the pyrolysis process was evaluated. It is shown that polymeric materials tend to remain at a larger particle size and thus, this fraction has the greatest mass loss during pyrolysis. A thermo gravimetric analysis (TGA) performed in all polymeric matter revealed the optimum pyrolysis temperature is around 500°C. Temperatures above 500°C continue to degrade matter, but mass loss rate is 6.25 times smaller. This study demonstrates the use of pyrolysis can remove >99% of the polymeric matter from PV modules, which assists the recycling of this hazardous waste and avoids its disposal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. A field-emission pressure sensor of nano-crystalline silicon film

    Institute of Scientific and Technical Information of China (English)

    廖波; 韩建保

    2001-01-01

    The prototype of a field-emission pressure sensor with a novel structure based on the quantum tunnel effect is designed and manufactured, where a cathode emitter array is fabricated on the same silicon plate as the sensible film. For an integrated structure, not only the alignment and vacuum bonding between the anode and cathode are easy to be realized, but also a fine sensibility is guaranteed. For example, the measured current density emitted from the effective area of the sensor can reach 53.5 A/m2 when the exterior electric field is 5.6 x 105 V/m. Furthermore, it is demonstrated by finite element method simulation that the reduction in sensor sensitivity caused by emitters on the sensible film is negligible. The difference between the maximum deflections of the sensible films with and without emitters under specified pressure is less than 0.4 %. Therefore, it can be concluded that the novel field-emission sensor structure is reasonable.

  5. Planarization process of single crystalline silicon asperity under abrasive rolling effect studied by molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Si, Lina [Tsinghua University, State Key Laboratory of Tribology, Beijing (China); Beijing Institute of Technology, School of Mechanical Engineering, Beijing (China); Guo, Dan; Luo, Jianbin; Xie, Guoxin [Tsinghua University, State Key Laboratory of Tribology, Beijing (China)

    2012-10-15

    In the chemical mechanical polishing (CMP) process, the complex behaviors of abrasive particles play important roles in the planarization of wafer surface. Particles embedded in the pad remove materials by ploughing, while particles immersed in the slurry by rolling across the wafer surface. In this paper, processes of the particle rolling across a silicon surface with an asperity under various down forces and external driving forces were studied using molecular dynamics (MD) simulation method. The simulations clarified the asperity shape evolution during the rolling process and analyzed the energy changes of the simulation system and the interaction forces acted on the silica particle. It was shown that both the down force and the driving force had important influences on the amount of the material removed. With relatively small down forces and driving forces applied on the particle, the material removal occurred mainly in the front end of the asperity; when the down forces and driving forces were large enough, e.g., 100 nN, the material removal could take place at the whole top part of the asperity. The analysis of energy changes and interaction forces provided favorable explanations to the simulation results. (orig.)

  6. Influence of the ion synthesis and ion doping regimes on the effect of sensitization of erbium emission by silicon nanoclusters in silicon dioxide films

    Science.gov (United States)

    Korolev, D. S.; Kostyuk, A. B.; Belov, A. I.; Mikhaylov, A. N.; Dudin, Yu. A.; Bobrov, A. I.; Malekhonova, N. V.; Pavlov, D. A.; Tetelbaum, D. I.

    2013-11-01

    The photoluminescence spectra of erbium centers in SiO2 films with ion-synthesized silicon nanoclusters under nonresonant excitation were investigated. Erbium was introduced into thermal SiO2 films by ion implantation. The dependences of photoluminescence intensity on the dose, the order of ion implantation of Si and Er, the annealing temperature, and additional Ar+ and P+ ion irradiation regimes, i.e., factors determining the influence of radiation damage and doping on sensitization of erbium luminescence by silicon nanoclusters, were determined. It was found that the sensitization effect and its amplification due to doping with phosphorus are most pronounced under the conditions where nanoclusters are amorphous. The quenching of photoluminescence due to radiation damage in this case manifests itself to a lesser extent than for crystalline nanoclusters. The role of various factors in the observed regularities was discussed in the framework of the existing concepts of the mechanisms of light emission and energy exchange in the system of silicon nanoclusters and erbium centers.

  7. Cat-doping: Novel method for phosphorus and boron shallow doping in crystalline silicon at 80 °C

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Hideki; Hayakawa, Taro; Ohta, Tatsunori; Nakashima, Yuki; Miyamoto, Motoharu; Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke [Japan Advanced Institute of Science and Technology (JAIST), Asahidai, Nomi-shi, Ishikawa-ken 923-1292 (Japan)

    2014-09-21

    Phosphorus (P) or boron (B) atoms can be doped at temperatures as low as 80 to 350 °C, when crystalline silicon (c-Si) is exposed only for a few minutes to species generated by catalytic cracking reaction of phosphine (PH₃) or diborane (B₂H₆) with heated tungsten (W) catalyzer. This paper is to investigate systematically this novel doping method, “Cat-doping”, in detail. The electrical properties of P or B doped layers are studied by the Van der Pauw method based on the Hall effects measurement. The profiles of P or B atoms in c-Si are observed by secondary ion mass spectrometry mainly from back side of samples to eliminate knock-on effects. It is confirmed that the surface of p-type c-Si is converted to n-type by P Cat-doping at 80 °C, and similarly, that of n-type c-Si is to p-type by B Cat-doping. The doping depth is as shallow as 5 nm or less and the electrically activated doping concentration is 10¹⁸ to 10¹⁹cm⁻³ for both P and B doping. It is also found that the surface potential of c-Si is controlled by the shallow Cat-doping and that the surface recombination velocity of minority carriers in c-Si can be enormously lowered by this potential control.

  8. Low temperature boron doping into crystalline silicon by boron-containing species generated in Cat-CVD apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Tatsunori, E-mail: s1130011@jaist.ac.jp [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Koyama, Koichi [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ohdaira, Keisuke [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Matsumura, Hideki [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2015-01-30

    We have discovered that phosphorus (P) atoms can be doped into crystalline silicon (c-Si) at temperatures below 350 °C or even at 80 °C by using species generated by catalytic cracking reaction of phosphine (PH{sub 3}) molecules with heated tungsten (W) catalyzer in Cat-CVD apparatus. As further investigation, here, we study the feasibility of low temperature doping of boron (B) atoms into c-Si by using decomposed species generated similarly from diborane (B{sub 2}H{sub 6}) molecules. Dependency of properties of doped layers on catalyzer temperature (T{sub cat}) and substrate temperature (T{sub s}) is studied by both the Van der Pauw method based on the Hall-effect measurements and secondary ion mass spectroscopy (SIMS) for B doping in addition to P doping. It is found that, similarly to P doping, the surface of n-type c-Si is converted to p-type even at T{sub s} = 80 °C for T{sub cat} over 800 °C when c-Si is exposed to B{sub 2}H{sub 6} cracked species for a few minutes, and that the heat of substrate over 300 °C is likely to help for B doping contrary to P doping.

  9. Optimized absorption of solar radiations in nano-structured thin films of crystalline silicon via a genetic algorithm

    Science.gov (United States)

    Mayer, Alexandre; Muller, Jérôme; Herman, Aline; Deparis, Olivier

    2015-08-01

    We developed a genetic algorithm to achieve optimal absorption of solar radiation in nano-structured thin films of crystalline silicon (c-Si) for applications in photovoltaics. The device includes on the front side a periodic array of inverted pyramids, with conformal passivation layer (a-Si:H or AlOx) and anti-reflection coating (SiNx). The device also includes on the back side a passivation layer (a-Si:H) and a flat reflector (ITO and Ag). The geometrical parameters of the inverted pyramids as well as the thickness of the different layers must be adjusted in order to maximize the absorption of solar radiations in the c-Si. The genetic algorithm enables the determination of optimal solutions that lead to high performances by evaluating only a reduced number of parameter combinations. The results achieved by the genetic algorithm for a 40μm thick c-Si lead to short-circuit currents of 37 mA/cm2 when a-Si:H is used for the front-side passivation and 39.1 mA/cm2 when transparent AlOx is used instead.

  10. A Multi-Criterion Analysis of Cross-Strait Co-Opetitive Strategy in the Crystalline Silicon Solar Cell Industry

    Directory of Open Access Journals (Sweden)

    Hsiao-Chi Chen

    2014-01-01

    Full Text Available The research adopts multi-criterion analysis to face cross-strait cooperative and competitive (co-opetitive strategies problem in the crystalline silicon solar cell industry between Taiwan and China. The analysis framework is based on the national competitiveness. The Analytical Hierarchy Process (AHP approach and TOPSIS analysis are applied to analyze firm-level data, gathered from the solar cell companies across the Taiwan Strait. For the Taiwanese firms, their relative national competitiveness lies in technology development, domestic market, international competition in related industries, and subsidy policy. For the Chinese firms, domestic market, procurement conditions, customization, intellectual resources, risk capital, and human quality are found to be their competitive advantages. Both China and Taiwan have entered into the emerging solar cell industry, with an aim to climb beyond the ladder of catch up. The results have shown that Taiwan and China can explore the possibility of forging strategic alliances by exploiting national competitiveness on the demand side. Above all, the paper has managed to spotlight demand conditions as the crucial factors for China and Taiwan to enhance their international competitiveness in the emerging solar cell industry.

  11. Improving Crystalline Silicon Solar Cell Efficiency Using Graded-Refractive-Index SiON/ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    Yung-Chun Tu

    2015-01-01

    Full Text Available The fabrication of silicon oxynitride (SiON/ZnO nanotube (NT arrays and their application in improving the energy conversion efficiency (η of crystalline Si-based solar cells (SCs are reported. The SiON/ZnO NT arrays have a graded-refractive-index that varies from 3.5 (Si to 1.9~2.0 (Si3N4 and ZnO to 1.72~1.75 (SiON to 1 (air. Experimental results show that the use of 0.4 μm long ZnO NT arrays coated with a 150 nm thick SiON film increases Δη/η by 39.2% under AM 1.5 G (100 mW/cm2 illumination as compared to that of regular SCs with a Si3N4/micropyramid surface. This enhancement can be attributed to SiON/ZnO NT arrays effectively releasing surface reflection and minimizing Fresnel loss.

  12. Optical Evaluation of the Rear Contacts of Crystalline Silicon Solar Cells by Coupled Electromagnetic and Statistical Ray-Optics Modeling

    KAUST Repository

    Dabirian, Ali

    2017-02-15

    High-efficiency crystalline silicon (c-Si) solar cells increasingly feature sophisticated electron and hole contacts aimed at minimizing electronic losses. At the rear of photovoltaic devices, such contacts—usually consisting of stacks of functional layers—offer opportunities to enhance the infrared response of the solar cells. Here, we propose an accurate and simple modeling procedure to evaluate the infrared performance of rear contacts in c-Si solar cells. Our method combines full-wave electromagnetic modeling of the rear contact with a statistical ray optics model to obtain the fraction of optical energy dissipated from the rear contact relative to that absorbed by the Si wafer. Using this technique, we study the impact of the refractive index, extinction coefficient, and thickness of the rear-passivating layer and establish basic design rules. In addition, we evaluate novel optical structures, including stratified thin films, nanoparticle composites, and conductive nanowires embedded in a low-index dielectric matrix, for integration into advanced rear contacts in c-Si photovoltaic devices. From an optical perspective, nanowire structures preserving low contact resistance appear to be the most effective approach to mitigating dissipation losses from the rear contact.

  13. Relationship between cross-linking conditions of ethylene vinyl acetate and potential induced degradation for crystalline silicon photovoltaic modules

    Science.gov (United States)

    Jonai, Sachiko; Hara, Kohjiro; Tsutsui, Yuji; Nakahama, Hidenari; Masuda, Atsushi

    2015-08-01

    In this study, we investigated the relationship in crystalline silicon (c-Si) photovoltaic (PV) modules between the cross-linking level of copolymer of ethylene and vinyl acetate (EVA) as the encapsulant and the degree of degradation due to potential induced degradation (PID) phenomenon. We used three methods for the determination of cross-linking level of EVA: xylene method, which is one of the solvent extraction methods (SEM), curing degree by differential scanning calorimetry (DSC), and viscoelastic properties by dynamic mechanical analysis (DMA). The results indicate that degradation of PV modules by PID test depends on the cross-linking level of EVA. The PV modules encapsulated by EVA with higher cross-linking level show lower degradation degree due to PID phenomenon. Also we showed that EVA with higher cross-linking level tended to be higher volume resistivity. This tendency is similar to that for electrical resistance value during the PID test. The PID test was also done by changing thickness of EVA between front cover glass and c-Si with the same cross-linking level. The PV modules encapsulated by thicker EVA between front cover glass and c-Si cell show lower degradation by PID. From these results, the PV modules encapsulated by EVA with higher cross-linking level, higher volume resistivity and increased thickness would be tolerant of PID phenomenon.

  14. Biomimetic spiral grating for stable and highly efficient absorption in crystalline silicon thin-film solar cells

    KAUST Repository

    Hou, Jin

    2017-09-12

    By emulating the phyllotaxis structure of natural plants, which has an efficient and stable light capture capability, a two-dimensional spiral grating is introduced on the surface of crystalline silicon solar cells to obtain both efficient and stable light absorption. Using the rigorous coupled wave analysis method, the absorption performance on structural parameter variations of spiral gratings is investigated firstly. Owing to diffraction resonance and excellent superficies antireflection, the integrated absorption of the optimal spiral grating cell is raised by about 77 percent compared with the conventional slab cell. Moreover, though a 15 percent deviation of structural parameters from the optimal spiral grating is applied, only a 5 percent decrease of the absorption is observed. This reveals that the performance of the proposed grating would tolerate large structural variations. Furthermore, the angular and polarization dependence on the absorption of the optimized cell is studied. For average polarizations, a small decrease of only 11 percent from the maximum absorption is observed within an incident angle ranging from −70 to 70 degrees. The results show promising application potentials of the biomimetic spiral grating in the solar cell.

  15. Means of Improvement the Efficiency of Concentrator Crystalline Silicon Solar Cells%提高聚光单晶硅太阳电池效率的途径

    Institute of Scientific and Technical Information of China (English)

    张燎; 金文进; 薛岩

    2012-01-01

    聚光太阳能电池具有效率高、成本低等优势。从电池结构出发,着重总结了背面点接触结构、双面陷光、双面钝化、减薄电池厚度和减小发射区饱和电流密度等新技术措施对提高聚光晶体硅电池效率的重要性和优势,同时也指出了现有工艺存在的问题,最后展望了聚光单晶硅太阳能电池工艺发展的可能方向。特别指出:聚光单晶硅电池效率大幅度提高将是硅电池结构设计理论和制备工艺的的重大突破.%Concentrator solar cells have good prospects for superiority of high efficiency and low cost.This review summarizes the importance and advantages of improvement the conversion efficiency of concentrator crystalline silicon solar cells,especially focuses on the structure of back-surface point contact,double-sided light trapping,double-sided anti-reflection with double-sided passivation,thinning the thickness of the cells and reduces the emitter saturation current density and other new technology initiatives.These measures have high value to promote efficiency and decrease costs of the concentrator crystalline silicon solar cells.And it points out that the existing process problems and the possible direction of technology development.Finally,prospects on concentrator crystalline silicon solar cells are discussed,and a major breakthrough of design theory and preparation process is predicted for substantial improvement the conversion efficiency of concentrator crystalline silicon solar cells.

  16. Formation of silicon nanoislands on crystalline silicon substrates by thermal annealing of silicon rich oxide deposited by low pressure chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yu Zhenrui [Department of Electronics, INAOE, Apartado 51, Puebla, Puebla 72000 (Mexico); Aceves-Mijares, Mariano [Department of Electronics, INAOE, Apartado 51, Puebla, Puebla 72000 (Mexico); Luna-Lopez, A [Department of Electronics, INAOE, Apartado 51, Puebla, Puebla 72000 (Mexico); Du Jinhui [College of Material Science and Chemistry Engineering, Tianjin Polytechnical University (China); Bian Dongcai [College of Material Science and Chemistry Engineering, Tianjin Polytechnical University (China)

    2006-10-14

    We report the preparation and characterization of Si nanoislands grown on a c-Si substrate by thermal annealing of silicon-rich oxide (SRO) films deposited using a conventional low pressure chemical vapour deposition (LPCVD) technique. Transmission electron microscopy revealed that a high density of Si nanoislands was formed on the surface of the c-Si substrate during thermal annealing. The nanoislands are nanocrystallites with the same crystal orientation as the substrate. The strain at the c-Si/SRO interface is probably the main reason for the nucleation of the self-assembled Si nanoislands that epitaxially grow on the c-Si substrate. The proposed method is very simple and compatible with Si integrated circuit technology.

  17. Desenvolvimento de sistemas líquido-cristalinos empregando silicone fluido de co-polímero glicol e poliéter funcional siloxano Development of liquid-crystalline systems using silicon glycol copolymer and polyether functional siloxane

    Directory of Open Access Journals (Sweden)

    Marlus Chorilli

    2009-01-01

    Full Text Available For the construction of the phase diagrams, the method of the aqueous titration was used. There were prepared 5 ternary diagrams, varying the surfactant and the oil phase. The liquid-crystalline phases were identified by polarized light microscopy. The formulations prepared with silicon glycol copolymer, polyether functional siloxane (PFS and water (S1 and with diisopropyl adipate, PFS and water (S4 presented liquid-crystalline phases with lamellar arrangement. Moreover, after 15 days in hot oven (37 ºC, the formulations presented hexagonal arrangement, evidencing the influence of the temperature in the organization of the system.

  18. Role of the crystalline form of titanium dioxide nanoparticles: Rutile, and not anatase, induces toxic effects in Balb/3T3 mouse fibroblasts.

    Science.gov (United States)

    Uboldi, Chiara; Urbán, Patricia; Gilliland, Douglas; Bajak, Edyta; Valsami-Jones, Eugenia; Ponti, Jessica; Rossi, François

    2016-03-01

    The wide use of titanium dioxide nanoparticles (TiO2 NPs) in industrial applications requires the investigation of their effects on human health. In this context, we investigated the effects of nanosized and bulk titania in two different crystalline forms (anatase and rutile) in vitro. By colony forming efficiency assay, a dose-dependent reduction of the clonogenic activity of Balb/3T3 mouse fibroblasts was detected in the presence of rutile, but not in the case of anatase NPs. Similarly, the cell transformation assay and the micronucleus test showed that rutile TiO2 NPs were able to induce type-III foci formation in Balb/3T3 cells and appeared to be slightly genotoxic, whereas anatase TiO2 NPs did not induce any significant neoplastic or genotoxic effect. Additionally, we investigated the interaction of TiO2 NPs with Balb/3T3 cells and quantified the in vitro uptake of titania using mass spectrometry. Results showed that the internalization was independent of the crystalline form of TiO2 NPs but size-dependent, as nano-titania were taken up more than their respective bulk materials. In conclusion, we demonstrated that the cytotoxic, neoplastic and genotoxic effects triggered in Balb/3T3 cells by TiO2 NPs depend on the crystalline form of the nanomaterial, whereas the internalization is regulated by the particle size.

  19. Facile synthesis of silicon carbide-titanium dioxide semiconducting nanocomposite using pulsed laser ablation technique and its performance in photovoltaic dye sensitized solar cell and photocatalytic water purification

    Science.gov (United States)

    Gondal, M. A.; Ilyas, A. M.; Baig, Umair

    2016-08-01

    Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO2) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet-visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

  20. Investigation of charges carrier density in phosphorus and boron doped SiN{sub x}:H layers for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Paviet-Salomon, B., E-mail: bertrand.paviet-salomon@epfl.ch [Commissariat à l’Énergie Atomique (CEA), Laboratoire d’Innovation pour les Technologies des Énergies Nouvelles et les nanomatériaux (LITEN), Institut National de l’Énergie Solaire - INES, 50 avenue du Lac Léman, 73377 Le Bourget du Lac (France); Gall, S. [Commissariat à l’Énergie Atomique (CEA), Laboratoire d’Innovation pour les Technologies des Énergies Nouvelles et les nanomatériaux (LITEN), Institut National de l’Énergie Solaire - INES, 50 avenue du Lac Léman, 73377 Le Bourget du Lac (France); Slaoui, A. [Institut de l’Électronique du Solide et des Systèmes (InESS), Unité Mixte de Recherche 7163 Centre National de la Recherche Scientifique-Université de Strasbourg (UMR 7163 CNRS-UDS), 23 rue du Loess, BP 20 CR, 67037 Strasbourg (France)

    2013-05-15

    Highlights: ► We investigate the properties of phosphorus and boron-doped silicon nitride films. ► Phosphorus-doped layers yield higher lifetimes than undoped ones. ► The fixed charges density decreases when increasing the films phosphorus content. ► Boron-doped films feature very low lifetimes. ► These doped layers are of particular interest for crystalline silicon solar cells. -- Abstract: Dielectric layers are of major importance in crystalline silicon solar cells processing, especially as anti-reflection coatings and for surface passivation purposes. In this paper we investigate the fixed charge densities (Q{sub fix}) and the effective lifetimes (τ{sub eff}) of phosphorus (P) and boron (B) doped silicon nitride layers deposited by plasma-enhanced chemical vapour deposition. P-doped layers exhibit a higher τ{sub eff} than standard undoped layers. In contrast, B-doped layers exhibit lower τ{sub eff}. A strong Q{sub fix} decrease is to be seen when increasing the P content within the film. Based on numerical simulations we also demonstrate that the passivation obtained with P- and B-doped layers are limited by the interface states rather than by the fixed charges.

  1. Technology development of the nano-crystalline silicon thin film materials%纳米晶硅薄膜材料的技术发展

    Institute of Scientific and Technical Information of China (English)

    吴大维; 吴越侠; 唐志斌

    2012-01-01

    The recent development of the nano - crystalline silicon thin film material is reviewed in this paper. Some ideas is proposed to promote advances of the silicon thin film solar cells. In this paper, we make come discussions on the development of silicon thin film solar cells and predict the prospect of latest ones.%本文综述了硅基薄膜材料的发展历程;提出了一些促进硅基薄膜电池技术进步的思路;并对硅 基薄膜电池的发展进行了有益的探讨,对最新的硅基薄膜太阳能电池作了展望.

  2. Vanadium dioxide thin films prepared on silicon by low temperature MBE growth and ex-situ annealing

    Science.gov (United States)

    Homm, Pia; van Bilzen, Bart; Menghini, Mariela; Locquet, Jean-Pierre; Ivanova, Todora; Sanchez, Luis; Sanchis, Pablo

    Vanadium dioxide (VO2) is a material that shows an insulator to metal transition (IMT) near room temperature. This property can be exploited for applications in field effect devices, electro-optical switches and nonlinear circuit components. We have prepared VO2 thin films on silicon wafers by combining a low temperature MBE growth with an ex-situ annealing at high temperature. We investigated the structural, electrical and optical characteristics of films with thicknesses ranging from 10 to 100 nm. We have also studied the influence of the substrate cleaning. The films grown with our method are polycrystalline with a preferred orientation in the (011) direction of the monoclinic phase. For the films produced on silicon with a native oxide, an IMT at around 75 °C is observed. The magnitude of the resistance change across the IMT decreases with thickness while the refractive index at room temperature corresponds with values reported in the literature for thin films. The successful growth of VO2 films on silicon with good electrical and optical properties is an important step towards the integration of VO2 in novel devices. The authors acknowledge financial support from the FWO project G052010N10 and EU-FP7 SITOGA project. PH acknowledges support from Becas Chile - CONICYT.

  3. Effect of the Nd content on the structural and photoluminescence properties of silicon-rich silicon dioxide thin films

    Directory of Open Access Journals (Sweden)

    Debieu Olivier

    2011-01-01

    Full Text Available Abstract In this article, the microstructure and photoluminescence (PL properties of Nd-doped silicon-rich silicon oxide (SRSO are reported as a function of the annealing temperature and the Nd concentration. The thin films, which were grown on Si substrates by reactive magnetron co-sputtering, contain the same Si excess as determined by Rutherford backscattering spectrometry. Fourier transform infrared (FTIR spectra show that a phase separation occurs during the annealing because of the condensation of the Si excess resulting in the formation of silicon nanoparticles (Si-np as detected by high-resolution transmission electron microscopy and X-ray diffraction (XRD measurements. Under non-resonant excitation at 488 nm, our Nd-doped SRSO films simultaneously exhibited PL from Si-np and Nd3+ demonstrating the efficient energy transfer between Si-np and Nd3+ and the sensitizing effect of Si-np. Upon increasing the Nd concentration from 0.08 to 4.9 at.%, our samples revealed a progressive quenching of the Nd3+ PL which can be correlated with the concomitant increase of disorder within the host matrix as shown by FTIR experiments. Moreover, the presence of Nd-oxide nanocrystals in the highest Nd-doped sample was established by XRD. It is, therefore, suggested that the Nd clustering, as well as disorder, are responsible for the concentration quenching of the PL of Nd3+.

  4. Nanostructures having crystalline and amorphous phases

    Science.gov (United States)

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  5. The effect of light soaking on crystalline silicon surface passivation by atomic layer deposited Al2O3

    Science.gov (United States)

    Liao, Baochen; Stangl, Rolf; Mueller, Thomas; Lin, Fen; Bhatia, Charanjit S.; Hoex, Bram

    2013-01-01

    The effect of light soaking of crystalline silicon wafer lifetime samples surface passivated by thermal atomic layer deposited (ALD) Al2O3 is investigated in this paper. Contrary to other passivation materials used in solar cell applications (i.e., SiO2, SiNx), using thermal ALD Al2O3, an increase in effective carrier lifetime after light soaking under standard testing conditions is observed for both p-type (˜45%) and n-type (˜60%) FZ c-Si lifetime samples. After light soaking and storing the samples in a dark and dry environment, the effective lifetime decreases again and practically returns to the value before light soaking. The rate of lifetime decrease after light soaking is significantly slower than the rate of lifetime increase by light soaking. To investigate the underlying mechanism, corona charge experiments are carried out on p-type c-Si samples before and after light soaking. The results indicate that the negative fixed charge density Qf present in the Al2O3 films increases due to the light soaking, which results in an improved field-effect passivation. Numerical calculations also confirm that the improved field-effect passivation is the main contributor for the increased effective lifetime after light soaking. To further understand the light soaking phenomenon, a kinetic model—a charge trapping/de-trapping model—is proposed to explain the time dependent behavior of the lifetime increase/decrease observed under/after light soaking. The trap model fits the experimental results very well. The observed light enhanced passivation for ALD Al2O3 passivated c-Si is of technological relevance, because solar cell devices operate under illumination, thus an increase in solar cell efficiency due to light soaking can be expected.

  6. Effects of neutral particle beam on nano-crystalline silicon thin films, with application to thin film transistor backplane for flexible active matrix organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Nyoung; Song, Byoung Chul; Lee, Dong Hyeok [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of); Yoo, Suk Jae; Lee, Bonju [National Fusion Research Institute, 52, Yuseong-Gu, Deajeon, 305-333 (Korea, Republic of); Hong, MunPyo, E-mail: goodmoon@korea.ac.kr [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of)

    2011-08-01

    A novel deposition process for nano-crystalline silicon (nc-Si) thin films was developed using neutral beam assisted chemical vapor deposition (NBaCVD) technology for the application of the thin film transistor (TFT) backplane of flexible active matrix organic light emitting diode (AMOLED). During the formation of a nc-Si thin film, the energetic particles enhance nano-sized crystalline rather microcrystalline Si in thin films. Neutral Particle Beam (NPB) affects the crystallinity in two ways: (1) NPB energy enhances nano-crystallinity through kinetic energy transfer and chemical annealing, and (2) heavier NPB (such as Ar) induces damage and amorphization through energetic particle impinging. Nc-Si thin film properties effectively can be changed by the reflector bias. As increase of NPB energy limits growing the crystalline, the performance of TFT supports this NPB behavior. The results of nc-Si TFT by NBaCVD demonstrate the technical potentials of neutral beam based processes for achieving high stability and reduced leakage in TFT backplanes for AMOLEDs.

  7. Errantum: Treatment of human astrocytoma U87 cells with silicon dioxide nanoparticles lowers their survival and alters their expression of mitochondrial and cell signaling proteins

    Directory of Open Access Journals (Sweden)

    Lai JCK

    2010-12-01

    Full Text Available Lai JCK, Ananthakrishnan G, Jandhyam S, et al. Treatment of human astrocytoma U87 cells with silicon dioxide nanoparticles lowers their survival and alters their expression of mitochondrial and cell signaling proteins. Int J Nanomedicine. 2010;5:715–723.The wrong image was used in Figure 5 on page 719.

  8. Choline-sensing carbon paste electrode containing polyaniline (pani)-silicon dioxide composite-modified choline oxidase.

    Science.gov (United States)

    Özdemir, Merve; Arslan, Halit

    2014-02-01

    In this study, a novel carbon paste electrode (CPE) was prepared using the salt form of polyaniline (pani)-silicon dioxide composite that is sensitive to choline. Choline oxidase (ChO) enzyme was immobilized to modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Determination of choline was carried out by the oxidation of enzymatically produced H2O2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated, and the optimum parameters were found to be 6.0 and 60°C, respectively. The linear working range of the electrode was 5.0 × 10(-7)-1.0 × 10(-5) M, R(2) = 0.922. The storage stability and operation stability of the enzyme electrode were also studied.

  9. Dielectrophoretic trapping of multilayer DNA origami nanostructures and DNA origami-induced local destruction of silicon dioxide.

    Science.gov (United States)

    Shen, Boxuan; Linko, Veikko; Dietz, Hendrik; Toppari, J Jussi

    2015-01-01

    DNA origami is a widely used method for fabrication of custom-shaped nanostructures. However, to utilize such structures, one needs to controllably position them on nanoscale. Here we demonstrate how different types of 3D scaffolded multilayer origamis can be accurately anchored to lithographically fabricated nanoelectrodes on a silicon dioxide substrate by DEP. Straight brick-like origami structures, constructed both in square (SQL) and honeycomb lattices, as well as curved "C"-shaped and angular "L"-shaped origamis were trapped with nanoscale precision and single-structure accuracy. We show that the positioning and immobilization of all these structures can be realized with or without thiol-linkers. In general, structural deformations of the origami during the DEP trapping are highly dependent on the shape and the construction of the structure. The SQL brick turned out to be the most robust structure under the high DEP forces, and accordingly, its single-structure trapping yield was also highest. In addition, the electrical conductivity of single immobilized plain brick-like structures was characterized. The electrical measurements revealed that the conductivity is negligible (insulating behavior). However, we observed that the trapping process of the SQL brick equipped with thiol-linkers tended to induce an etched "nanocanyon" in the silicon dioxide substrate. The nanocanyon was formed exactly between the electrodes, that is, at the location of the DEP-trapped origami. The results show that the demonstrated DEP-trapping technique can be readily exploited in assembling and arranging complex multilayered origami geometries. In addition, DNA origamis could be utilized in DEP-assisted deformation of the substrates onto which they are attached.

  10. Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO thin films

    Directory of Open Access Journals (Sweden)

    Subodh K. Gautam

    2015-12-01

    Full Text Available The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO2 lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb+5 in the TiO2 lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR spectra of films with small size crystallites shows stiffening of about 4 cm−1 for the Eg(1 mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B1g mode exhibits a large anomalous softening of 20 cm−1 with asymmetrical broadening; which was not reported for the case of pure TiO2 crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb5+ doping induced reduction of Ti4+ ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  11. Simulation calculations of efficiencies and silicon consumption for CH3NH3PbI3-x-y Br x Cl y /crystalline silicon tandem solar cells

    Science.gov (United States)

    Zhang, Lili; Xie, Ziang; Tian, Fuyang; Qin, Guogang

    2017-04-01

    Much attention has been paid to two-subcell tandem solar cells (TSCs) with crystalline silicon (c-Si) as the bottom cell (TSC-Si). Previous works have pointed out that the optimal band gap, E g, of the top cell material for a TSC-Si is around 1.75 eV. With a tunable E g and better stability than MAPbI3 (MA  =  CH3NH3), MAPbI3-x-y Br x Cl y is a promising candidate for the top cell material of a TSC-Si. In this work, calculations concerning the E g, refractive index and extinction coefficient of MAPbI3-x-y Br x Cl y are performed using first-principles calculations including the spin-orbit coupling (SOC) effect. MAPbI3-x-y Br x Cl y with five sets of x and y, which have a E g around 1.75 eV, are obtained. On this basis, absorption of the perovskite top cell is calculated applying the Lambert-Beer model (LBM) and the transfer matrix model (TMM), respectively. Considering the Auger recombination in the c-Si bottom cell and radiation coupling between the two subcells, the efficiencies for MAPbI3-x-y Br x Cl y /c-Si TSCs with the five sets of x and y are calculated. Among them, the MAPbI2.375Br0.5Cl0.125/c-Si TSC achieves the highest efficiency of 35.1% with a 440 nm thick top cell and 50 µm thick c-Si when applying the LBM. When applying the TMM, the highest efficiency of 32.5% is predicted with a 580 nm thick MAPbI2.375Br0.5Cl0.125 top cell and 50 µm thick c-Si. Compared with the limiting efficiency of 27.1% for a 190 µm thick c-Si single junction solar cell (SC), the MAPbI2.375Br0.5Cl0.125/c-Si TSC shows a superior performance of high efficiency and low c-Si consumption.

  12. Carbon mediated reduction of silicon dioxide and growth of copper silicide particles in uniform width channels

    DEFF Research Database (Denmark)

    Pizzocchero, Filippo; Bøggild, Peter; Booth, Tim

    2013-01-01

    channels, which are aligned with the intersections of the (100) surface of the wafer and the {110} planes on an oxidized silicon wafer, as well as endotaxial copper silicide nanoparticles within the wafer bulk. We apply energy dispersive x-ray spectroscopy, in combination with scanning and transmission......We show that surface arc-discharge deposited carbon plays a critical intermediary role in the breakdown of thermally grown oxide diffusion barriers of 90 nm on a silicon wafer at 1035°C in an Ar/H2 atmosphere, resulting in the formation of epitaxial copper silicide particles in ≈ 10 μm wide...

  13. Supercritical Carbon Dioxide-Assisted Process for Well-Dispersed Silicon/Graphene Composite as a Li ion Battery Anode

    Science.gov (United States)

    Lee, Sang Ha; Park, Sengyoen; Kim, Min; Yoon, Dohyeon; Chanthad, Chalathorn; Cho, Misuk; Kim, Jaehoon; Park, Jong Hyeok; Lee, Youngkwan

    2016-01-01

    The silicon (Si)/graphene composite has been touted as one of the most promising anode materials for lithium ion batteries. However, the optimal fabrication method for this composite remains a challenge. Here, we developed a novel method using supercritical carbon dioxide (scCO2) to intercalate Si nanoparticles into graphene nanosheets. Silicon was modified with a thin layer of polyaniline, which assisted the dispersion of graphene sheets by introducing π-π interaction. Using scCO2, well-dispersed Si/graphene composite was successfully obtained in a short time under mild temperature. The composite showed high cycle performance (1,789 mAh/g after 250 cycles) and rate capability (1,690 mAh/g at a current density of 4,000 mA/g). This study provides a new approach for cost-effective and scalable preparation of a Si/graphene composite using scCO2 for a highly stable lithium battery anode material. PMID:27535108

  14. Supercritical Carbon Dioxide-Assisted Process for Well-Dispersed Silicon/Graphene Composite as a Li ion Battery Anode

    Science.gov (United States)

    Lee, Sang Ha; Park, Sengyoen; Kim, Min; Yoon, Dohyeon; Chanthad, Chalathorn; Cho, Misuk; Kim, Jaehoon; Park, Jong Hyeok; Lee, Youngkwan

    2016-08-01

    The silicon (Si)/graphene composite has been touted as one of the most promising anode materials for lithium ion batteries. However, the optimal fabrication method for this composite remains a challenge. Here, we developed a novel method using supercritical carbon dioxide (scCO2) to intercalate Si nanoparticles into graphene nanosheets. Silicon was modified with a thin layer of polyaniline, which assisted the dispersion of graphene sheets by introducing π-π interaction. Using scCO2, well-dispersed Si/graphene composite was successfully obtained in a short time under mild temperature. The composite showed high cycle performance (1,789 mAh/g after 250 cycles) and rate capability (1,690 mAh/g at a current density of 4,000 mA/g). This study provides a new approach for cost-effective and scalable preparation of a Si/graphene composite using scCO2 for a highly stable lithium battery anode material.

  15. Dielectric elastomer actuators of silicone rubber-titanium dioxide composites obtained by dielectrophoretic assembly of filler particles

    Science.gov (United States)

    Javadi, S.; Razzaghi-Kashani, M.

    2010-04-01

    Formation of controlled morphology of fillers in polymeric composites may be difficult to achieve by conventional methods such as mechanical shear or chemical methods. Tunable structure of filler and anisotropic properties in composites can be obtained by exploiting dielectrophoretic assembly of fillers in a polymer composite by using electric fields. In this study, different concentrations of Titanium Dioxide (TiO2) particles in silicone rubber matrix were assembled in a chain-like structure by using an alternating electric field. Silicone rubber matrix was vulcanized to transform the liquid to solid and maintain the filler structure in the desired direction. Generation of chain structure of filler was verified by Scanning Electron Microscopy (SEM) and equilibrium swelling. It was shown that dielectric permittivity of the oriented composite is higher whereas its dielectric loss factor is lower in the orientation (thickness) direction than those for the composites with random distribution of filler. This phenomenon was in agreement with results of dynamic-mechanical loss factor for these composites, and can be utilized in more efficient dielectric elastomer actuators. Elastic modulus is higher for the structured samples, but presence of titania filler induced a softening effect at higher strains where the actuators are practically being pre-stretched. A critical concentration of filler was distinguished as the percolation point at which the change in dielectric behavior is amplified. Using a simple blocking-force measurement, potential advantages of structured composites over the ones with randomly-distributed filler was explained for potential dielectric elastomer actuator applications.

  16. Zero lattice mismatch and twin-free single crystalline ScN buffer layers for GaN growth on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Lupina, L.; Zoellner, M. H.; Dietrich, B.; Capellini, G. [IHP, Im Technologiepark 25, 15236 Frankfurt, Oder (Germany); Niermann, T.; Lehmann, M. [Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin (Germany); Thapa, S. B.; Haeberlen, M.; Storck, P. [SILTRONIC AG, Hanns-Seidel-Platz 4, 81737 München (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt, Oder (Germany); BTU Cottbus, Konrad-Zuse-Str. 1, 03046 Cottbus (Germany)

    2015-11-16

    We report the growth of thin ScN layers deposited by plasma-assisted molecular beam epitaxy on Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) substrates. Using x-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we find that ScN films grown at 600 °C are single crystalline, twin-free with rock-salt crystal structure, and exhibit a direct optical band gap of 2.2 eV. A high degree of crystalline perfection and a very good lattice matching between ScN and GaN (misfit < 0.1%) makes the ScN/Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} buffer system a very promising template for the growth of high quality GaN layers on silicon.

  17. Photo-induced density-of-states variation measured by DLTS method in intrinsic micro-crystalline silicon (i-μc-Si:H) films

    Science.gov (United States)

    Wang, J.; Sun, Q. S.; Liu, H. N.; He, Y. L.

    1987-06-01

    This paper advances a measurement and two calculations of a high-frequency DLTS method for the density-of-states g(E) of intrinsic micro-crystalline and amorphous silicon film. The method surmounts the difficulties of DLTS measurement of i-a-Si:H or i-μc-Si:H samples and applies the common high-frequency DLTS to it, while the temperature of measurement is extended below 77K. Following the method, we successfully observed the obvious increase of density-of-states produced by illumination.

  18. Research and development of photovoltaic power system. Characterization and control of surface/interface recombination velocity of crystalline silicon thin films; Taiyoko hatsuden system no kenkyu kaihatsu. Silicon kessho usumaku ni okeru hyomen kaimen saiketsugo sokudo no hyoka to seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, H. [Hokkaido University, Sapporo (Japan). Faculty of Engineering

    1994-12-01

    This paper reports the result obtained during fiscal 1994 on characterization and control of surface/interface recombination velocity of crystalline silicon thin films. To optimize design and manufacture of solar cells, it is necessary to identify correctly resistance factor (or doping) of bulk of materials, bulk minority carrier life, and recombination velocity on surface, passivation interface and electrode interface. A group in the Hokkaido University has been working since a few years ago on development of non-contact and non-destructive photo-luminescence surface level spectroscopy (PLS{sup 3}). A new non-contact C-V method was also introduced. Using these methods, basic discussions were given on possibility of separate measurements on surface/interface and bulk characteristics of solar cell materials. The PLS{sup 3} method and the non-contact C-V method were used for experimental discussions on evaluation of silicon mono-crystalline and poly-crystalline materials. Discussions were given on separate evaluations by using the DLTS method. 10 figs., 2 tabs.

  19. The effect of heating power on impurity formation and transport during the holding phase in a Bridgman furnace for directional solidification of multi-crystalline silicon

    Science.gov (United States)

    Ellingsen, Kjerstin; Lindholm, Dag; M`Hamdi, Mohammed

    2016-06-01

    Oxygen and carbon are the most common impurities in multi-crystalline silicon. The general mechanism for formation and transport of O and C in the solidification furnace is as follows: oxygen from the silica crucible comes into the melt and combines with a silicon atom and evaporates at the gas/melt interface in the form of silicon oxide (SiO). Argon inert gas, injected into the furnace chamber, carries the SiO to the hot graphite fixtures, where it reacts with carbon to form carbon monoxide (CO) and silicon carbide (SiC). CO is carried by the gas to the melt free surface, where it dissociates into carbon and oxygen. Finally, during solidification oxygen and carbon are incorporated into the crystal. A global furnace model accounting for heat transfer, melt flow, gas flow and impurity transport has been applied to investigate the oxygen and carbon formation and transport in a vertical Bridgman furnace during the holding phase when the furnace is at its hottest. A case study is performed to investigate the effect of the applied heating power on the carbon and oxygen concentrations in the melt prior to solidification.

  20. Facile synthesis of silicon carbide-titanium dioxide semiconducting nanocomposite using pulsed laser ablation technique and its performance in photovoltaic dye sensitized solar cell and photocatalytic water purification

    Energy Technology Data Exchange (ETDEWEB)

    Gondal, M.A., E-mail: magondal@kfupm.edu.sa [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Ilyas, A.M. [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Baig, Umair [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Center of Excellence for Scientific Research Collaboration with MIT, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2016-08-15

    Highlights: • SiC–TiO{sub 2} semiconducting nanocomposites synthesized by nanosecond PLAL technique. • Synthesized nanocomposites were morphologically and optically characterized. • Nanocomposites were applied for the photocatalytic degradation of toxic organic dye. • Photovoltaic performance was investigated in dye sensitized solar cell. - Abstract: Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO{sub 2}) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet–visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

  1. Leakage current conduction and reliability assessment of passivating thin silicon dioxide films on n-4H-SiC

    Science.gov (United States)

    Samanta, Piyas; Mandal, Krishna C.

    2016-09-01

    We have analyzed the mechanisms of leakage current conduction in passivating silicon dioxide (SiO2) films grown on (0 0 0 1) silicon (Si) face of n-type 4H-SiC (silicon carbide). It was observed that the experimentally measured gate current density in metal-oxide-silicon carbide (MOSiC) structures under positive gate bias at an oxide field Eox above 5 MV/cm is comprised of Fowler-Nordheim (FN) tunneling of electrons from the accumulated n-4H-SiC and Poole-Frenkel (PF) emission of trapped electrons from the localized neutral traps in the SiO2 gap, IFN and IPF, respectively at temperatures between 27 and 200 °C. In MOSiC structures, PF mechanism dominates FN tunneling of electrons from the accumulation layer of n-4H-SiC due to high density (up to 1013 cm-2) of carbon-related acceptor-like traps located at about 2.5 eV below the SiO2 conduction band (CB). These current conduction mechanisms were taken into account in studying hole injection/trapping into 10 nm-thick tunnel oxide on the Si face of 4H-SiC during electron injection from n-4H-SiC under high-field electrical stress with positive bias on the heavily doped n-type polysilicon (n+-polySi) gate at a wide range of temperatures between 27 and 200 °C. Holes were generated in the n+-polySi anode material by the hot-electrons during their transport through thin oxide films at oxide electric fields Eox from 5.6 to 8.0 MV/cm (prior to the intrinsic oxide breakdown field). Time-to-breakdown tBD of the gate dielectric was found to follow reciprocal field (1/E) model irrespective of stress temperatures. Despite the significant amount of process-induced interfacial electron traps contributing to a large amount of leakage current via PF emission in thermally grown SiO2 on the Si-face of n-4H-SiC, MOSiC devices having a 10 nm-thick SiO2 film can be safely used in 5 V TTL logic circuits over a period of 10 years.

  2. In-situ optical emission spectroscopy diagnostic of plasma ignition impact on crystalline silicon passivation by a-Si:H films

    Science.gov (United States)

    Meddeb, Hosny; Bearda, Twan; Abdulraheem, Yaser; Dimassi, Wissem; Ezzaouia, Hatem; Gordon, Ivan; Szlufcik, Jozef; Poortmans, Jef

    2016-08-01

    The influence of the plasma ignition condition during PECVD deposition from a silane/hydrogen mixture on the amorphous silicon passivation of crystalline silicon surface is investigated. The changes in this process step mainly consist in varying the power density for very brief durations in between 1 s and 3 s. We find that the ignition phase contributes significantly in the film growth, especially in the a-Si:H/c-Si interface formation. In particular, the deposition rate increases with ignition power density. TEM cross-section inspection presents a rougher a-Si:H/c-Si interface with higher plasma power and thus, a tendency for nano-clusters formation caused by the crystalline nature of the substrate. In-situ plasma diagnostics reveal the gradual raise up of IHa*/ISiH* with the power density leading to worse SiH* abstraction to the surface. Whereas, time-resolved optical emission spectroscopy explains the possible recombination mechanism in the plasma due to higher-silane related reactive species (HSRS) formation via polymerization reactions. Our results point out that the ignition conditions with a rather low power for longer time give the best passivation, resulting an effective lifetime up to 9 ms.

  3. Anomalous behavior of B{sub 1g} mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Subodh K., E-mail: subodhkgtm@gmail.com, E-mail: fouran@gmail.com; Ojha, S.; Singh, Fouran, E-mail: subodhkgtm@gmail.com, E-mail: fouran@gmail.com [Material Science Group, Inter University Accelerator Centre, New Delhi -110067 (India); Gautam, Naina [Department of Electronic Science, University of Delhi South Campus, New Delhi - 110023 (India); Singh, R. G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi– 110043 (India); Shukla, D. K. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India)

    2015-12-15

    The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO) thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO{sub 2} lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb{sup +5} in the TiO{sub 2} lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR) spectra of films with small size crystallites shows stiffening of about 4 cm{sup −1} for the E{sub g(1)} mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B{sub 1g} mode exhibits a large anomalous softening of 20 cm{sup −1} with asymmetrical broadening; which was not reported for the case of pure TiO{sub 2} crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb{sup 5+} doping induced reduction of Ti{sup 4+} ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS) and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  4. Electrical and Optical Characterization of Sputtered Silicon Dioxide, Indium Tin Oxide, and Silicon Dioxide/Indium Tin Oxide Antireflection Coating on Single-Junction GaAs Solar Cells

    Directory of Open Access Journals (Sweden)

    Wen-Jeng Ho

    2017-06-01

    Full Text Available This study characterized the electrical and optical properties of single-junction GaAs solar cells coated with antireflective layers of silicon dioxide (SiO2, indium tin oxide (ITO, and a hybrid layer of SiO2/ITO applied using Radio frequency (RF sputtering. The conductivity and transparency of the ITO film were characterized prior to application on GaAs cells. Reverse saturation-current and ideality factor were used to evaluate the passivation performance of the various coatings on GaAs solar cells. Optical reflectance and external quantum efficiency response were used to evaluate the antireflective performance of the coatings. Photovoltaic current-voltage measurements were used to confirm the efficiency enhancement obtained by the presence of the anti-reflective coatings. The conversion efficiency of the GaAs cells with an ITO antireflective coating (23.52% exceeded that of cells with a SiO2 antireflective coating (21.92%. Due to lower series resistance and higher short-circuit current-density, the carrier collection of the GaAs cell with ITO coating exceeded that of the cell with a SiO2/ITO coating.

  5. 双面单晶硅光伏电池技术及工艺探索%Exploration of Crystalline Silicon Bifacial Photovoltaic Cell Technology and Process

    Institute of Scientific and Technical Information of China (English)

    张中伟; 张小宾; 侯泽荣; 黄仑

    2014-01-01

    对双面晶体硅电池技术和工艺做了初步的阐述,并以双面P型单晶硅电池为研究对象,对双面电池制程中的硼扩散、边缘刻蚀、硼扩散面钝化几个关键技术和工艺展开研究和探索,得出其中工艺参数与电池性能之间的相互联系,实验制作得到的P型双面电池片最高综合效率达20.04%。这些技术和制备工艺流程对于未来高效晶硅电池的研发和生产具有重要的参考价值。%This paper introduces the bifacial crystalline silicon photovoltaic cell technology and production process, using P type monocrystalline silicon bifacial solar cell as research object, the introduction is follwed by investigations on such key technical aspects and processes such as boron diffusion, edge isolation etching and boron diffused surface passivation as well as study on the relationship between process parameters and cell performance. The results reveal that the best bifacial cell fabricated in experiments had a combined efficiency of 20. 04%, Which are valuable for further high efficient crystalline silicon solar cell research and production.

  6. Synthesis, surface morphology, and photoluminescence properties of anatase iron-doped titanium dioxide nano-crystalline films.

    Science.gov (United States)

    Zhang, Jinzhong; Chen, Xiangui; Shen, Yude; Li, Yawei; Hu, Zhigao; Chu, Junhao

    2011-07-28

    Iron (Fe)-doped (0 to 4%) TiO(2) nano-crystalline (nc) films with the grain size of about 25 nm have been deposited on n-type Si (100) substrates by a facile nonhydrolytic sol-gel processing. X-ray diffraction measurements prove that the films are polycrystalline and present the pure anatase phase. X-ray photoelectron spectroscopy spectra indicate that the chemical valent state of Fe element is +3 and the Fe(3+) ions replace the Ti(4+) sites. The Fe dopant effects on the surface morphology, microstructure, and dielectric functions of the nc-Fe/TiO(2) films have been studied by atomic force microscope, ultraviolet Raman scattering and spectroscopic ellipsometry. With increasing Fe composition, the intensity of Raman-active mode B(1g) increases, while that of the A(1g) phonon mode decreases. The dielectric functions have been uniquely extracted by fitting ellipsometric spectra with the Adachi's dielectric function model and a four-phase layered model. It is found that the real part of dielectric functions in the transparent region and the optical band gap slightly decrease with the Fe composition due to the introduction of acceptor level Fe t(2g). Finally, the composition and temperature dependence of the surface and lattice defects in the Fe/TiO(2) films have been investigated by photoluminescence spectra in detail. At room temperature, the emission intensities decrease with increasing Fe compositions since the Fe incorporation could prolong the radiative lifetime and/or shorten the non-radiative lifetime. By analyzing the low temperature photoluminescence spectra, the intensities and positions of five emission peaks and shoulder structure can be unambiguously assigned. The phenomena could be reasonably explained by the physical mechanisms such as oxygen vacancies, localized excitons, self-trapped excitons, and indirect transitions, which are strongly related to the electronic band structure perturbed by the Fe doping.

  7. 以技术创新推动晶体硅太阳能电池智慧生产线建设%Intelligent Production Line Construction of Crystalline Silicon Solar Cell through Technological innovation

    Institute of Scientific and Technical Information of China (English)

    谢建国; 赵加宝

    2014-01-01

    In this paper, the status of the technology of crystalline silicon solar cell production line was reviewed, the future trends of crystal silicon solar cell technology is analyzed, and the technical characteristic of modern crystalline silicon cell production line was summarized, proposing that the combination of innovative technology and equipment, efficient process automation, intelligent monitoring and decision-making are the three main features of modern intelligent crystalline silicon cell production line. On this basis, an intelligent crystalline silicon cell manufacturing system frame with modern technical features was proposed, and its structure, design and implementation were briefly introduced.%综述了晶体硅太阳能电池生产线的技术现状,并结合晶体硅电池技术的未来发展方向,分析了晶体硅太阳能电池生产线技术的发展趋势,认为创新工艺及设备、高产能及高效自动化、监控与决策智能化是未来晶体硅太阳能电池生产线的三大主要特征,在此基础上,提出了一种晶体硅太阳能电池智慧生产线,简要介绍了其结构组成,特点及实现。1

  8. CMOS-compatible catalytic growth of graphene on a silicon dioxide substrate

    Science.gov (United States)

    Lee, Jae-Hyun; Kim, Min-Sung; Lim, Jae-Young; Jung, Su-Ho; Kang, Seog-Gyun; Shin, Hyeon-Jin; Choi, Jae-Young; Hwang, Sung-Woo; Whang, Dongmok

    2016-08-01

    We report the direct growth of graphene on a dielectric SiO2 surface by utilizing complementary metal oxide semiconductor compatible germane as a gas-phase catalyst. Results of Raman spectroscopy and XPS confirmed that the synthesized graphene consist of a sp2 hybridized carbon network. We were able to fabricate graphene field effect transistors without the wet etching process, and the calculated mobility was ˜160 cm2/V.s at high carrier concentration (n = 3 × 1012 cm-2). Furthermore, the crystallinity and morphology of graphene is easily controlled from single-layer graphene to graphene nanowall structures by adjusting the reaction conditions. The results of this study verify the promising catalytic graphene growth method on a non-catalytic insulating surface without metal contaminations.

  9. Comparative study. Thin-film technology (si-a) compared to crystalline silicon in real operating conditions; Estudio comparativo. Tecnologia de capa fina (Si-a) frente a silicio cristalino en condiciones reales de funcionamiento

    Energy Technology Data Exchange (ETDEWEB)

    Izard Gomez-Rodulfo, J.; Avellaner, J.; Sanchez, E.; Torreblanca, J.

    2010-07-01

    We present a comparative study of thin film solar modules (amorphous silicon) compared to crystalline silicon modules. This study was conducted in real operating conditions using a test bench able to obtain the characteristic curve of several modules in sequence. defined the parameter efficiency index to characterize the extent to which actual performance is close to ideal. Finally we have calculated the energy that would produce each module in the day and efficiency in relation to the energy which ideally should produce. (Author)

  10. The effects of different types of nano-silicon dioxide additives on the properties of sludge ash mortar.

    Science.gov (United States)

    Luo, Huan-Lin; Chang, Wei-Che; Lin, Deng-Fong

    2009-04-01

    To improve the drawbacks caused by the sludge ash replacement in mortar, the previous studies have shown that the early strength and durability of sludge ash/cement mortar are improved by adding nano-silicon dioxide (nano-SiO2) to mortar. In this article, three types of nano-SiO2--SS, HS, and SP (manufacturer code names)--were applied to sludge ash/cement mixture to make paste or mortar specimens. The object is to further extend the recycle of the sludge ash by determining the better type of nano-SiO2 additive to improve properties of sludge ash/ cement paste or mortar. The cement was replaced by 0, 10, 20, and 30% of sludge ash, and 0 and 2% of nano-SiO2 additives were added to the sludge ash paste or mortar specimens. Tests such as setting time, compressive strength, scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance, and thermogravimetric analysis/differential thermal analysis were performed in this study. Test results show that nano-SiO2 additives can not only effectively increase the hydration product (calcium silicate hydrate [C-S-H] gel), but also make the crystal structure denser. Among the three types of nano-SiO2 additive, the SS type can best improve the properties of sludge ash/cement paste or mortar, followed by the SP and HS types.

  11. Rheology of dispersions of xanthan gum, locust bean gum and mixed biopolymer gel with silicon dioxide nanoparticles.

    Science.gov (United States)

    Kennedy, Jordan R M; Kent, Katherine E; Brown, Jennifer R

    2015-03-01

    Mixed xanthan gum (XG) and locust bean gum (LBG) biopolymers form thermally reversible gels of interest in tissue engineering and drug delivery. 1% solutions of XG, LBG and 1:1 ratio XG/LBG mixed gels (LX) containing silicon dioxide (SiO2) nanoparticles were rheologically characterized with respect to nanoparticle concentration and temperature. 10% nanoparticles in XG created larger domains of associated polymer, resulting in enhanced viscosity and viscoelastic moduli. In LBG with 10% particles, transient viscosity and a gel-sol transition occurred due to particle bridging and aggregation. In the LX gel, 10% SiO2 particles caused an increase in elasticity. When ramping temperature from 25°C to 85°C, the complex modulus for all solutions containing 10% SiO2 was relatively constant, indicating that nanoparticles counteracted the effect of temperature on the material properties. Understanding the influence of nanoparticle loading on material properties is necessary for biopolymer material development where property prediction and control are critical.

  12. Comparative study of solution-phase and vapor-phase deposition of aminosilanes on silicon dioxide surfaces.

    Science.gov (United States)

    Yadav, Amrita R; Sriram, Rashmi; Carter, Jared A; Miller, Benjamin L

    2014-02-01

    The uniformity of aminosilane layers typically used for the modification of hydroxyl bearing surfaces such as silicon dioxide is critical for a wide variety of applications, including biosensors. However, in spite of many studies that have been undertaken on surface silanization, there remains a paucity of easy-to-implement deposition methods reproducibly yielding smooth aminosilane monolayers. In this study, solution- and vapor-phase deposition methods for three aminoalkoxysilanes differing in the number of reactive groups (3-aminopropyl triethoxysilane (APTES), 3-aminopropyl methyl diethoxysilane (APMDES) and 3-aminopropyl dimethyl ethoxysilane (APDMES)) were assessed with the aim of identifying methods that yield highly uniform and reproducible silane layers that are resistant to minor procedural variations. Silane film quality was characterized based on measured thickness, hydrophilicity and surface roughness. Additionally, hydrolytic stability of the films was assessed via these thickness and contact angle values following desorption in water. We found that two simple solution-phase methods, an aqueous deposition of APTES and a toluene based deposition of APDMES, yielded high quality silane layers that exhibit comparable characteristics to those deposited via vapor-phase methods.

  13. Role of Silicon Dioxide Filler on Mechanical and Dry Sliding Wear Behaviour of Glass-Epoxy Composites

    Directory of Open Access Journals (Sweden)

    Naveed Anjum

    2013-01-01

    Full Text Available The mechanical properties and dry sliding wear behaviour of glass fabric reinforced epoxy (G-E composite with varying weight percentage of silicon dioxide (SiO2 filler have been studied in the present work. The influence of sliding distance, velocity, and applied normal load on dry sliding wear behaviour has been considered using Taguchi's L9 orthogonal array. Addition of SiO2 increased the density, hardness, flexural, and impact strengths of G-E composite. Results of dry sliding wear tests showed increasing wear volume with increase in sliding distance, load, and sliding velocity for G-E and SiO2 filled G-E composites. Taguchi's results indicate that the sliding distance played a significant role followed by applied load, sliding velocity, and SiO2 loading. Scanning electron micrographs of the worn surfaces of composite samples at different test parameters show smooth surface, microploughing, and fine grooves under low load and velocity. However, severe damage of matrix with debonding and fiber breakage was seen at high load and velocity especially in unfilled G-E composite.

  14. Photoemission electron microscopy of arrays of submicron nickel rods in a silicon dioxide matrix

    Science.gov (United States)

    Turishchev, S. Yu.; Parinova, E. V.; Kronast, F.; Ovsyannikov, R.; Malashchenok, N. V.; Streltsov, E. A.; Ivanov, D. K.; Fedotov, A. K.

    2014-09-01

    Arrays of Ni rods (˜500 nm diameter) formed by the ion-track technology in combination with electrochemical deposition into a SiO2 matrix on the surface of single-crystal silicon plates have been investigated using photoemission electron microscopy with high-intensity synchrotron (undulator) radiation. An analysis of the Ni L 2,3 X-ray absorption near-edge structure (XANES) spectra has demonstrated that rod-like structures in pores and connecting bridges between the rods are formed by a metallic nickel phase, which is stable to oxidation by atmospheric oxygen. No formation of intermediate compound phases (nickel silicides and oxides) is observed at the Ni/SiO2 heterojunction, whereas oxidized nickel(II) species are identified on the surface of the SiO2 matrix, which presumably can be attributed to nickel silicate and hydroxide compounds formed upon nickel(II) chemisorption in electrochemical deposition electrolytes.

  15. Application of Aloe vera gel instead of silicon dioxide as organic dielectric material in microelectronics

    Directory of Open Access Journals (Sweden)

    Rana Sardar Masud

    2015-09-01

    Full Text Available Organic materials are now being used in a wide range of microelectronic applications in parallel with inorganic materials, because of their superior properties, environmental safety, and low cost. This paper describes the characterization of Aloe vera gel (AVG, a new organic dielectric material. The surface morphology, spatial distribution of elements, and structural characteristics of an AVG layer were examined using scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX, and X-ray diffraction (XRD, respectively. The resistance of the AVG layer, determined using a four-probe station, was 640 Ω EDX showed that the elements contained in the layer were carbon, oxygen, aluminum, silicon, calcium, potassium, and copper. The XRD results suggested that the sample primarily consisted of bornite (Cu5FeS4, geerite (Cu8S5, sal ammoniac (NH4Cl, and carobbite (KF.

  16. Grazing incidence X-ray fluorescence analysis of buried interfaces in periodically structured crystalline silicon thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Eisenhauer, David; Preidel, Veit; Becker, Christiane [Young Investigator Group Nanostructured Silicon for Photovoltaic and Photonic Implementations (Nano-SIPPE), Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Pollakowski, Beatrix; Beckhoff, Burkhard [Physikalisch-Technische Bundesanstalt, Berlin (Germany); Baumann, Jonas; Kanngiesser, Birgit [Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin (Germany); Amkreutz, Daniel; Rech, Bernd [Institut Silizium Photovoltaik, Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Back, Franziska; Rudigier-Voigt, Eveline [SCHOTT AG, Mainz (Germany)

    2015-03-01

    We present grazing incidence X-ray fluorescence (GIXRF) experiments on 3D periodically textured interfaces of liquid phase crystallized silicon thin-film solar cells on glass. The influence of functional layers (SiO{sub x} or SiO{sub x}/SiC{sub x}) - placed between glass substrate and silicon during crystallization - on the final carbon and oxygen contaminations inside the silicon was analyzed. Baring of the buried structured silicon surface prior to GIXRF measurement was achieved by removal of the original nano-imprinted glass substrate by wet-chemical etching. A broad angle of incidence distribution was determined for the X-ray radiation impinging on this textured surface. Optical simulations were performed in order to estimate the incident radiation intensity on the structured surface profile considering total reflection and attenuation effects. The results indicate a much lower contamination level for SiO{sub x} compared to the SiO{sub x}/SiC{sub x} interlayers, and about 25% increased contamination when comparing structured with planar silicon layers, both correlating with the corresponding solar cell performances. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. 太阳能级多晶硅片表面制绒的研究%Research of Texturization on Multi-crystalline Silicon Surface for Solar Cell

    Institute of Scientific and Technical Information of China (English)

    管世兵; 殷伟琦; 严俊; 顾顺超

    2013-01-01

    主要研究多晶硅太阳能电池片工业制绒的酸腐蚀过程,腐蚀液是由HNO3、HF和H2 SiF6组成的混合液,未添加其他试剂作为反应缓释剂;采用SEM和紫外分光光度计对多晶硅片表面制绒形貌进行观察和检测分析.实验过程中,按照工业生产的实际模型,首先研究确定了最佳腐蚀时间为2 min,之后主要研究了酸腐蚀过程中的H2SiF6浓度对多晶硅表面制绒效果的影响,优化得到H2SiF6的最低含量为2%,并确定最佳腐蚀工艺条件,为进一步回收利用腐蚀废液提供依据.%The acid etching process for industrial texturing of multi-crystalline silicon solar cells was studied. In this process, multi-crystalline silicon wafers were textured in acid solution, which was constituted with HNO3, HF and H2SiF6, without any other reagents as release agent. By using the SEM and UV spectrophotometer, detailed study of the surface morphology and optical properties of the different etched surfaces were carried out. During the experiment, the study was focused on the etching time at first, and obtained a best etching time of 2 min. Then the influence of H2SiF6 concentration in the acid solution on multi-crystalline silicon surface texturing effect was studied, with the actual model of industrial productioa From the analytical results, H2SiF6 content and etching conditions were optimized, which would be the basis for further recycling of waste solution.

  18. Co-implantation of carbon and nitrogen into silicon dioxide for synthesis of carbon nitride materials

    CERN Document Server

    Huang, M B; Nuesca, G; Moore, R

    2002-01-01

    Materials synthesis of carbon nitride has been attempted with co-implantation of carbon and nitrogen into thermally grown SiO sub 2. Following implantation of C and N ions to doses of 10 sup 1 sup 7 cm sup - sup 2 , thermal annealing of the implanted SiO sub 2 sample was conducted at 1000 degree sign C in an N sub 2 ambient. As evidenced in Fourier transform infrared measurements and X-ray photoelectron spectroscopy, different bonding configurations between C and N, including C-N single bonds, C=N double bonds and C=N triple bonds, were found to develop in the SiO sub 2 film after annealing. Chemical composition profiles obtained with secondary ion mass spectroscopy were correlated with the depth information of the chemical shifts of N 1s core-level electrons, allowing us to examine the formation of C-N bonding for different atomic concentration ratios between N and C. X-ray diffraction and transmission electron microscopy showed no sign of the formation of crystalline C sub 3 N sub 4 precipitates in the SiO ...

  19. Novel chemical cleaning of textured crystalline silicon for realizing surface recombination velocity <0.2 cm/s using passivation catalytic CVD SiN x /amorphous silicon stacked layers

    Science.gov (United States)

    Thanh Nguyen, Cong; Koyama, Koichi; Higashimine, Koichi; Terashima, Shigeki; Okamoto, Chikao; Sugiyama, Shuichiro; Ohdaira, Keisuke; Matsumura, Hideki

    2017-05-01

    In this study, the development of a novel chemical cleaning method suitable for textured surfaces of crystalline silicon (c-Si) used for solar cells is demonstrated. To remove contaminants from such textured structures, chemicals have to penetrate into their complicated fine structures. Thus, the viscosity, reaction activity, and surface tension of the chemicals are adjusted by increasing the reaction temperature or introducing a surfactant. Actually, the use of concentrated (conc.) sulfuric acid (H2SO4) of 140 °C and the introduction of methanol (CH3OH) to other chemicals contribute to the improvement of the cleaning ability in textured structures. The present cleaning method in conjunction with plasma-damage-less catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD passivation with silicon-nitride (SiN x )/amorphous silicon (a-Si) stacked layers, also contributes to the decrease in the surface recombination velocity (SRV) of c-Si. The maximum estimated SRV (SRVmax), evaluated under the assumed absence of recombination in bulk c-Si, is less than 1.1 cm/s for textured surfaces, and the real SRV, evaluated by changing the c-Si substrate thickness, is less than 0.2 cm/s.

  20. [Changes in proteome profiles of rat liver microsomes induced by silicon dioxide nanoparticles].

    Science.gov (United States)

    Tananova, O N; Arianova, E A; Gmoshinskii, I V; Toropygin, I Yu; Khryapova, E V; Trusov, N V; Khotimchenko, S A; Tutel'yan, V A

    2015-01-01

    The effect of daily intragastric administration of an aqueous dispersion of silicon nanoparticles (NPs) (the dose range from 1.0 mg/kg to 100 mg/kg body weight for 28 days) to rats on the proteomic profile of liver microsomes has been investigated by 2D-electrophoresis followed by subsequent mass spectrometry identification. The liver microsomal fraction was isolated by differential centrifugation and its protein composition was analyzed by 2D-polyacrylamide gel electrophoresis. Identification of protein spots was carried out using MALDI-TOF mass spectrometric analysis. The mass spectrometry analysis revealed the protein GRP78 (78 kD glucose-regulated protein precursor), belonging to the family of heat shock proteins. This protein present in animals of the control group was not detected in NP-treated rats of group 2 (1 mg/kg body weight/day) and group 3 (10 mg/kg body weight/day). This protein predominantly localized in the liver cell endoplasmic reticulum and plasma membrane has the chaperone biological activity. Possible mechanisms of the effects of engineered nanoparticles on biosynthetic processes in the body are discussed.

  1. Patterning human neuronal networks on photolithographically engineered silicon dioxide substrates functionalized with glial analogues.

    Science.gov (United States)

    Hughes, Mark A; Brennan, Paul M; Bunting, Andrew S; Cameron, Katherine; Murray, Alan F; Shipston, Mike J

    2014-05-01

    Interfacing neurons with silicon semiconductors is a challenge being tackled through various bioengineering approaches. Such constructs inform our understanding of neuronal coding and learning and ultimately guide us toward creating intelligent neuroprostheses. A fundamental prerequisite is to dictate the spatial organization of neuronal cells. We sought to pattern neurons using photolithographically defined arrays of polymer parylene-C, activated with fetal calf serum. We used a purified human neuronal cell line [Lund human mesencephalic (LUHMES)] to establish whether neurons remain viable when isolated on-chip or whether they require a supporting cell substrate. When cultured in isolation, LUHMES neurons failed to pattern and did not show any morphological signs of differentiation. We therefore sought a cell type with which to prepattern parylene regions, hypothesizing that this cellular template would enable secondary neuronal adhesion and network formation. From a range of cell lines tested, human embryonal kidney (HEK) 293 cells patterned with highest accuracy. LUHMES neurons adhered to pre-established HEK 293 cell clusters and this coculture environment promoted morphological differentiation of neurons. Neurites extended between islands of adherent cell somata, creating an orthogonally arranged neuronal network. HEK 293 cells appear to fulfill a role analogous to glia, dictating cell adhesion, and generating an environment conducive to neuronal survival. We next replaced HEK 293 cells with slower growing glioma-derived precursors. These primary human cells patterned accurately on parylene and provided a similarly effective scaffold for neuronal adhesion. These findings advance the use of this microfabrication-compatible platform for neuronal patterning.

  2. Temperature-dependency analysis and correction methods of in-situ power-loss estimation for crystalline silicon modules undergoing potential-induced degradation stress testing

    DEFF Research Database (Denmark)

    Spataru, Sergiu; Hacke, Peter; Sera, Dezso

    2015-01-01

    We propose a method of in-situ characterization of the photovoltaic module power at standard test conditions using superposition of the dark current-voltage (I-V) curve measured at elevated stress temperature during potential-induced degradation (PID) testing. PID chamber studies were performed...... duration and cost, avoids stress transients while ramping to and from the stress temperature, eliminates flash testing except at the initial and final data points, and enables significantly faster and more detailed acquisition of statistical data for future application of various statistical reliability...... on several crystalline silicon module designs to determine the extent to which the temperature dependency of maximum power is affected by the degradation of the modules. The results using the superposition principle show a mismatch between the power degradation measured at stress temperature and the power...

  3. Pilot-Scale Silicone Process for Low-Cost Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Farnum, Rachel; Perry, Robert; Wood, Benjamin

    2014-12-31

    GE Global Research is developing technology to remove carbon dioxide (CO 2) from the flue gas of coal-fired powerplants. A mixture of 3-aminopropyl end-capped polydimethylsiloxane (GAP-1m) and triethylene glycol (TEG) is the preferred CO2-capture solvent. GE Global Research was contracted by the Department of Energy to test a pilot-scale continuous CO2 absorption/desorption system using a GAP-1m/TEG mixture as the solvent. As part of that effort, an Environmental, Health, and Safety (EH&S) assessment for a CO2-capture system for a 550 MW coal-fired powerplant was conducted. Five components of the solvent, CAS#2469-55-8 (GAP-0), CAS#106214-84-0 (GAP-1-4), TEG, and methanol and xylene (minor contaminants from the aminosilicone) are included in this assessment. One by-product, GAP- 1m/SOX salt, and dodecylbenzenesulfonicacid (DDBSA) were also identified foranalysis. An EH&S assessment was also completed for the manufacturing process for the GAP-1m solvent. The chemicals associated with the manufacturing process include methanol, xylene, allyl chloride, potassium cyanate, sodium hydroxide (NaOH), tetramethyldisiloxane (TMDSO), tetramethyl ammonium hydroxide, Karstedt catalyst, octamethylcyclotetrasiloxane (D4), Aliquat 336, methyl carbamate, potassium chloride, trimethylamine, and (3-aminopropyl) dimethyl silanol. The toxicological effects of each component of both the CO2 capture system and the manufacturing process were defined, and control mechanisms necessary to comply with U.S. EH&S regulations are summarized. Engineering and control systems, including environmental abatement, are described for minimizing exposure and release of the chemical components. Proper handling and storage recommendations are made for each chemical to minimize risk to workers and the surrounding community.

  4. Effect of the CO2/SiH4 Ratio in the p-[mu]c-SiO:H Emitter Layer on the Performance of Crystalline Silicon Heterojunction Solar Cells

    National Research Council Canada - National Science Library

    Jaran Sritharathikhun; Taweewat Krajangsang; Apichan Moollakorn; Sorapong Inthisang; Amornrat Limmanee; Aswin Hongsingtong; Nattaphong Boriraksantikul; Tianchai Taratiwat; Nirod Akarapanjavit; Kobsak Sriprapha

    2014-01-01

    .... The reported work focused on the effects of the CO2/SiH4 ratio on the properties of p-μ c-SiO:H films and the effectiveness of the films as an emitter layer of crystalline silicon heterojunction (c-Si-HJ) solar cells. A p-μ c...

  5. Pilot-Scale Silicone Process for Low-Cost Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Surinder; Spiry, Irina; Wood, Benjamin; Hancu, Dan; Chen, Wei

    2014-07-01

    This report presents system and economicanalysis for a carbon-capture unit which uses an aminosilicone-based solvent for CO₂ capture in a pulverized coal (PC) boiler. The aminosilicone solvent is a 60/40 wt/wt mixture of 3-aminopropyl end-capped polydimethylsiloxane (GAP-1m) with tri-ethylene glycol (TEG) as a co-solvent. Forcomparison purposes, the report also shows results for a carbon-capture unit based on a conventional approach using mono-ethanol amine (MEA). The first year removal cost of CO₂ for the aminosilicone-based carbon-capture process is $46.04/ton of CO₂ as compared to $60.25/ton of CO₂ when MEA is used. The aminosilicone- based process has <77% of the CAPEX of a system using MEA solvent. The lower CAPEX is due to several factors, including the higher working capacity of the aminosilicone solvent compared the MEA, which reduces the solvent flow rate required, reducing equipment sizes. If it is determined that carbon steel can be used in the rich-lean heat exchanger in the carbon capture unit, the first year removal cost of CO₂ decreases to $44.12/ton. The aminosilicone-based solvent has a higherthermal stability than MEA, allowing desorption to be conducted at higher temperatures and pressures, decreasing the number of compressor stages needed. The aminosilicone-based solvent also has a lowervapor pressure, allowing the desorption to be conducted in a continuous-stirred tank reactor versus a more expensive packed column. The aminosilicone-based solvent has a lowerheat capacity, which decreases the heat load on the desorber. In summary, the amino-silicone solvent has significant advantages overconventional systems using MEA.

  6. Improvement of epitaxy and crystallinity in YBa2Cu3Oy thin films grown on silicon with double buffer of ECO/YSZ

    Institute of Scientific and Technical Information of China (English)

    GAO Ju; YANG Jian

    2006-01-01

    A novel double buffer of Eu2CuO4 (ECO)/YSZ (yttrium-stabilized zirconia) was developed for growing YBa2Cu3Oy (YBCO) thin films on Si substrates. In these films,the severe reaction between Si and YBCO is blocked by the first YSZ layer,whereas,the degradation of crystallinity and superconductivity in the grown YBCO is greatly improved by the second ECO layer. Such an ECO material possesses a very stable 214-T' structure and excellent compatibilities with YBCO and YSZ. The result shows that the epitaxy and crystallinity of YBCO deposited on Si could be considerably enhanced by using the ECO/YSZ double buffer. The grown films are characterized by high-resolution X-ray diffraction,grazing incidence X-ray reflection,and transmission electron microscopy (TEM),respectively. It is found that well defined interfaces are formed at YBCO/ECO/YSZ boundaries. No immediate layer could be seen. The defect density in all grown layers is kept at a lower level. The YBCO film surface turns out to be very smooth. These films have full superconducting transitions above 88 K and high current carrying capacity at 77 K. The successful growth of highly epitaxial YBCO thin films on silicon with ECO/YSZ buffer,demonstrate the advantages of such a double buffer structure.

  7. Silicon Diphosphide: A Si-Based Three-Dimensional Crystalline Framework as a High-Performance Li-Ion Battery Anode.

    Science.gov (United States)

    Kwon, Hyuk-Tae; Lee, Churl Kyoung; Jeon, Ki-Joon; Park, Cheol-Min

    2016-06-28

    The development of an electrode material for rechargeable Li-ion batteries (LIBs) and the understanding of its reaction mechanism play key roles in enhancing the electrochemical characteristics of LIBs for use in various portable electronics and electric vehicles. Here, we report a three-dimensional (3D) crystalline-framework-structured silicon diphosphide (SiP2) and its interesting electrochemical behaviors for superior LIBs. During Li insertion in the SiP2, a three-step electrochemical reaction mechanism, sequentially comprised of a topotactic transition (0.55-2 V), an amorphization (0.25-2 V), and a conversion (0-2 V), was thoroughly analyzed. On the basis of the three-step electrochemical reaction mechanism, excellent electrochemical properties, such as high initial capacities, high initial Coulombic efficiencies, stable cycle behaviors, and fast-rate capabilities, were attained from the preparation of a nanostructured SiP2/C composite. This 3D crystalline-framework-structured SiP2 compound will be a promising alternative anode material in the realization and mass production of excellent, rechargeable LIBs.

  8. Low cost sol–gel derived SiC–SiO{sub 2} nanocomposite as anti reflection layer for enhanced performance of crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jannat, Azmira [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Solar Energy Engineering, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Lee, Woojin [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Akhtar, M. Shaheer, E-mail: shaheerakhtar@jbnu.ac.kr [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); New & Renewable Energy Materials Development Center (NewREC), Chonbuk National University, Jeonbuk (Korea, Republic of); Li, Zhen Yu [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Yang, O.-Bong, E-mail: obyang@jbnu.ac.kr [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); New & Renewable Energy Materials Development Center (NewREC), Chonbuk National University, Jeonbuk (Korea, Republic of)

    2016-04-30

    Graphical abstract: - Highlights: • Sol–gel derived SiC–SiO{sub 2} nanocomposite was prepared. • It effectively coated as AR layer on p-type Si-wafer. • SiC–SiO{sub 2} layer on Si solar cells exhibited relatively low reflectance of 7.08%. • Fabricated Si solar cell attained highly comparable performance of 16.99% to commercial device. - Abstract: This paper describes the preparation, characterizations and the antireflection (AR) coating application in crystalline silicon solar cells of sol–gel derived SiC–SiO{sub 2} nanocomposite. The prepared SiC–SiO{sub 2} nanocomposite was effectively applied as AR layer on p-type Si-wafer via two step processes, where the sol–gel of precursor solution was first coated on p-type Si-wafer using spin coating at 2000 rpm and then subjected to annealing at 450 °C for 1 h. The crystalline, and structural observations revealed the existence of SiC and SiO{sub 2} phases, which noticeably confirmed the formation of SiC–SiO{sub 2} nanocomposite. The SiC–SiO{sub 2} layer on Si solar cells was found to be an excellent AR coating, exhibiting the low reflectance of 7.08% at wavelengths ranging from 400 to 1000 nm. The fabricated crystalline Si solar cell with SiC–SiO{sub 2} nanocomposite AR coating showed comparable power conversion efficiency of 16.99% to the conventional Si{sub x}N{sub x} AR coated Si solar cell. New and effective sol–gel derived SiC–SiO{sub 2} AR layer would offer a promising technique to produce high performance Si solar cells with low-cost.

  9. Potential of ITO nanoparticles formed by hydrogen treatment in PECVD for improved performance of back grid contact crystalline silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Sourav; Mitra, Suchismita; Dhar, Sukanta; Ghosh, Hemanta; Banerjee, Chandan, E-mail: chandanbanerjee74@gmail.com; Datta, Swapan K.; Saha, Hiranmoy

    2015-09-15

    Highlights: • Indium tin oxide (ITO) nanoparticles as back scatterers in c-Si solar cells. • ITO NP have comparatively low dissipative losses and tunable optical properties. • ITO NP formed by hydrogen plasma treatment on sputtered ITO film. • Enhanced absorption and carrier collection at longer wavelengths due to enhanced light trapping. - Abstract: This paper discusses the prospect of using indium tin oxide (ITO) nanoparticles as back scatterers in crystalline silicon solar cells instead of commonly used metal nanoparticles as ITO nanoparticles have comparatively low dissipative losses and tunable optical properties. ITO nanoparticles of ∼5–10 nm size is developed on the rear side of the solar cell by deposition of ∼5–10 nm thick ITO layer by DC magnetron sputtering followed by hydrogen treatment in PECVD. The silicon solar cell is fabricated in the laboratory using conventional method with grid metal contact at the back surface. Various characterizations like FESEM, TEM, AFM, XRD, EQE and IV characteristics are performed to analyze the morphology, chemical composition, optical characteristics and electrical performance of the device. ITO nanoparticles at the back surface of the solar cell significantly enhances the short circuit current, open circuit voltage and efficiency of the solar cell. These enhancements may be attributed to the increased absorption and carrier collection at longer wavelengths of solar spectrum due to enhanced light trapping by the ITO nanoparticles and surface passivation by the hydrogen treatment of the back surface.

  10. Heterogeneous reactions of methacrolein and methyl vinyl ketone: Kinetics and mechanisms of uptake and ozonolysis on silicon dioxide

    Science.gov (United States)

    Chen, Z. M.; Jie, C. Y.; Li, S.; Wang, H. L.; Wang, C. X.; Xu, J. R.; Hua, W.

    2008-11-01

    Methacrolein (MAC) and methyl vinyl ketone (MVK), two major first-generation products in the oxidation of isoprene, play important roles in tropospheric chemistry. However, little is known about their heterogeneous fate. Here we investigated the heterogeneous reactions of MAC and MVK on particles of silicon dioxide (SiO2), the major constituent of mineral dust in the troposphere, under simulated tropospheric conditions. We first investigated the adsorption and desorption processes. It was found that MAC and MVK molecules were adsorbed onto the surface of SiO2 particles by van der Waals forces and hydrogen bonding forces in a non-reactive state, and the presence of water vapor did not result in the formation of new substances but could decrease the adsorption ability by consuming isolated hydroxyl groups on the surface of SiO2 particles. The initial adsorption and desorption rates, initial uptake coefficients, and adsorption concentrations at equilibrium were determined at different relative humidities. Notably, in the desorption process, a considerable amount of MAC or MVK molecules remained on SiO2 particles in dry air but were almost completely desorbed in high-humid air. We also investigated the heterogeneous ozonolysis of MAC and MVK adsorbed onto SiO2 particles, determining product yields at different relative humidities. The heterogeneous ozonolysis of MAC and MVK adsorbed onto SiO2 particles yielded formaldehyde and methylglyoxal as the major secondary carbonyl products and formic acid and acetic acid as the major organic acid products, as in their gas-phase ozonolysis. However, the yield of two major organic peroxides, methyl hydroperoxide and hydroxymethyl hydroperoxide, was much greater in their heterogeneous ozonolysis than in their gas-phase ozonolysis. The mechanisms of heterogeneous ozonolysis of MAC and MVK onto the SiO2 surface are deduced.

  11. First-principles studies of di-arsenic interstitial and its implications for arsenic-interstitial diffusion in crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yonghyun [Microelectronics Research Center, University of Texas at Austin, Austin, TX 78758 (United States); Kirichenko, Taras A. [Freescale Semiconductor Inc., 3501 Ed Bluestein Blvd., Austin, TX 78721 (United States); Kong, Ning [Microelectronics Research Center, University of Texas at Austin, Austin, TX 78758 (United States); Larson, Larry [SEMATECH, 2706 Montopolis Drive., Austin, TX 78741 (United States); Banerjee, Sanjay K. [Microelectronics Research Center, University of Texas at Austin, Austin, TX 78758 (United States)], E-mail: banerjee@ece.utexas.edu

    2007-12-15

    We propose new structural configurations and novel diffusion mechanisms for neutral di-arsenic interstitial (As{sub 2}I{sub 2}) in silicon with a first-principle density functional theory simulation within the generalized gradient approximation. With an assumption of excess silicon interstitials and high arsenic concentrations, neutral As{sub 2}I{sub 2} is expected to be favorable and mobile with low-migration barrier. Moreover, because the diffusion barrier of arsenic interstitial pairs (AsI) is very low (< 0.2 eV) under the same conditions, As{sub 2}I{sub 2} can be easily formed and likely intermediate stage of larger arsenic interstitial clusters.

  12. Quantification of Power Losses of the Interdigitated Metallization of Crystalline Silicon Thin-Film Solar Cells on Glass

    Directory of Open Access Journals (Sweden)

    Peter J. Gress

    2012-01-01

    Full Text Available The metallization grid pattern is one of the most important design elements for high-efficiency solar cells. This paper presents a model based on the unit cell approach to accurately quantify the power losses of a specialized interdigitated metallization scheme for polycrystalline silicon thin-film solar cells on glass superstrates. The sum of the power losses can be minimized to produce an optimized grid-pattern design for a cell with specific parameters. The model is simulated with the standard parameters of a polycrystalline silicon solar cell, and areas for efficiency improvements are identified, namely, a reduction in emitter finger widths and a shift toward series-interconnected, high-voltage modules with very small cell sizes. Using the model to optimize future grid-pattern designs, higher cell and module efficiencies of such devices can be achieved.

  13. SEMICONDUCTOR TECHNOLOGY Texturization of mono-crystalline silicon solar cells in TMAH without the addition of surfactant

    Science.gov (United States)

    Weiying, Ou; Yao, Zhang; Hailing, Li; Lei, Zhao; Chunlan, Zhou; Hongwei, Diao; Min, Liu; Weiming, Lu; Jun, Zhang; Wenjing, Wang

    2010-10-01

    Etching was performed on (100) silicon wafers using silicon-dissolved tetramethylammonium hydroxide (TMAH) solutions without the addition of surfactant. Experiments were carried out in different TMAH concentrations at different temperatures for different etching times. The surface phenomena, etching rates, surface morphology and surface reflectance were analyzed. Experimental results show that the resulting surface covered with uniform pyramids can be realized with a small change in etching rates during the etching process. The etching mechanism is explained based on the experimental results and the theoretical considerations. It is suggested that all the components in the TMAH solutions play important roles in the etching process. Moreover, TMA+ ions may increase the wettability of the textured surface. A good textured surface can be obtained in conditions where the absorption of OH-/H2O is in equilibrium with that of TMA+/SiO2 (OH)22-.

  14. Quantification of Power Losses of the Interdigitated Metallization of Crystalline Silicon Thin-Film Solar Cells on Glass

    OpenAIRE

    Gress, Peter J.; Sergey Varlamov

    2012-01-01

    The metallization grid pattern is one of the most important design elements for high-efficiency solar cells. This paper presents a model based on the unit cell approach to accurately quantify the power losses of a specialized interdigitated metallization scheme for polycrystalline silicon thin-film solar cells on glass superstrates. The sum of the power losses can be minimized to produce an optimized grid-pattern design for a cell with specific parameters. The model is simulated with the stan...

  15. Lowest surface recombination velocity on n-type crystalline silicon using PECVD a-Si:H/SiNx bi-layer passivation

    Science.gov (United States)

    Stepanov, Dmitri S.; Chowdhury, Zahidur R.; Kherani, Nazir P.

    2011-08-01

    Energy conversion efficiency of crystalline silicon (c-Si) solar cells manufactured on thin substrates is strongly influenced by the recombination losses of photo-generated charge carriers at the surface and in its proximity. Intrinsic hydrogenated amorphous silicon (i-a-Si:H) deposited using DC saddle-field plasma enhanced chemical vapour deposition (PECVD) at a low temperature of ~200°C reduces recombination losses of photo-generated carriers through passivation of defects at the surface. This study reports on high quality surface passivation achieved using a dual layer approach wherein a 70nm amorphous silicon nitride (SiNx) capping layer is deposited on a less than 10nm thin i-a-Si:H layer. While the a-Si:H layer is effective in passivating the interface recombination sites, SiNx is deemed to incorporate field-effect passivation, thus providing a minority carrier mirror. Additionally, SiNx layer acts as an anti-reflection coating with a low absorption coefficient in the optical frequency range of interest. The SiNx deposition conditions, known to strongly influence the passivating quality of the dual layer structure, were systematically investigated using the response surface methodology (RSM). The optimal deposition parameters obtained from the RSM study were experimentally verified to yield the lowest surface recombination velocity of 3.5 cm/s on 1-2 Ω-cm n-type FZ c-Si using a PECVD a-Si:H/SiNx bi-layer passivation stack.

  16. Crystalline Silica Primer

    Science.gov (United States)

    ,

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  17. Recent Progress in the Development of Supercritical Carbon Dioxide-Soluble Metal Ion Extractants: Aggregation, Extraction, and Solubility Properties of Silicon-Substituted Alkylenediphosphonic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, Mark L.; McAlister, Daniel R.; Stepinski, Dominique C.; Zalupski, Peter R.; Dzilawa, Julie A.; Barrans, Richard E.; Hess, J.N.; Rubas, Audris V.; Chiarizia, Renato; Lubbers, Christopher M.; Scurto, Aaron M.; Brennecke, Joan F.; Herlinger, Albert W.

    2003-09-11

    Partially esterified alkylenediphosphonic acids (DPAs) have been shown to be effective reagents for the extraction of actinide ions from acidic aqueous solution into conventional organic solvents. Efforts to employ these compounds in supercritical fluid extraction have been hampered by their modest solubility in unmodified supercritical carbon dioxide (SC-CO2). In an effort to design DPAs that are soluble in SC-CO2, a variety of silicon-substituted alkylenediphosphonic acids have been prepared and characterized, and their behavior compared with that of conventional alkyl-substituted reagents. Silicon substitution is shown to enhance the CO2-philicity of the reagents, while other structural features, in particular, the number of methylene groups bridging the phosphorus atoms of the extractant, are shown to exert a significant influence on their aggregation and extraction properties. The identification of DPAs combining desirable extraction properties with adequate solubility in SC-CO2 is shown to be facilitated by the application of molecular connectivity indices.

  18. Silica-sol-based spin-coating barrier layer against phosphorous diffusion for crystalline silicon solar cells.

    Science.gov (United States)

    Uzum, Abdullah; Fukatsu, Ken; Kanda, Hiroyuki; Kimura, Yutaka; Tanimoto, Kenji; Yoshinaga, Seiya; Jiang, Yunjian; Ishikawa, Yasuaki; Uraoka, Yukiharu; Ito, Seigo

    2014-01-01

    The phosphorus barrier layers at the doping procedure of silicon wafers were fabricated using a spin-coating method with a mixture of silica-sol and tetramethylammonium hydroxide, which can be formed at the rear surface prior to the front phosphorus spin-on-demand (SOD) diffusion and directly annealed simultaneously with the front phosphorus layer. The optimization of coating thickness was obtained by changing the applied spin-coating speed; from 2,000 to 8,000 rpm. The CZ-Si p-type silicon solar cells were fabricated with/without using the rear silica-sol layer after taking the sheet resistance measurements, SIMS analysis, and SEM measurements of the silica-sol material evaluations into consideration. For the fabrication of solar cells, a spin-coating phosphorus source was used to form the n(+) emitter and was then diffused at 930°C for 35 min. The out-gas diffusion of phosphorus could be completely prevented by spin-coated silica-sol film placed on the rear side of the wafers coated prior to the diffusion process. A roughly 2% improvement in the conversion efficiency was observed when silica-sol was utilized during the phosphorus diffusion step. These results can suggest that the silica-sol material can be an attractive candidate for low-cost and easily applicable spin-coating barrier for any masking purpose involving phosphorus diffusion.

  19. Investigation of anti-reflection properties of crystalline silicon solar cell surface silicon nanowire arrays∗%晶体硅太阳电池表面纳米线阵列减反射特性研究

    Institute of Scientific and Technical Information of China (English)

    梁磊†; 徐琴芳; 忽满利; 孙浩; 向光华; 周利斌

    2013-01-01

      为增强晶体硅太阳电池的光利用率,提高光电转换效率,研究了硅纳米线阵列的光学散射性质.运用严格耦合波理论对硅纳米线阵列在310—1127 nm波段的反射率进行了模拟计算,用田口方法对硅纳米线阵列的表面传输效率进行了优化.结果表明,当硅纳米线阵列的周期为50 nm,占空比为0.6,高度约1000 nm时减反射效果最佳;该结构在上述波段的平均反射率约为2%,且在较大入射角度范围保持不变.采用金属催化化学腐蚀法,于室温、室压条件下在单晶硅表面制备周期为60 nm,占空比为0.53,高度为500 nm的硅纳米线阵列结构,其反射率的实验测试结果与计算模拟值相符,在上述波段的平均反射率为4%—5%,相对于单晶硅35%左右的反射率,减反射效果明显.这种减反射微结构能够在降低太阳电池成本的同时有效减小单晶硅表面的光反射损失,提高光电转换效率.%In order to trap more sunlight onto the crystalline silicon solar cell and improve the photo-electric conversion efficiency, it is very important to study the optical scattering properties of silicon nanowire arrays on silicon wafer. The rigorous coupled wave analysis method is used for optical simulation, and the Taguchi method is used for efficient optimization. The simulation results show that at the above-mentioned wavelengths the reflectance of the optimized structure is less than 2%, and also able to achieve the wide-angle antireflection. At room temperature and ambient pressure, the silicon nanowire arrays each with a period of 50 nm, duty ratio of 0.6 and height of 1000 nm are successfully prepared on mono-crystalline Si wafers using a novel metal-catalyzed chemical etching technique, the reflectance test results are consistent with simulation values. The average reflectance of the optimized structure over the above-mentioned wavelength range is 4%–5%, showing that the antireflection effect is obvious

  20. Enhancing the ultraviolet-visible-near infrared photovoltaic responses of crystalline-silicon solar cell by using aluminum nanoparticles

    Science.gov (United States)

    Hu, Fei; Zhou, Zhi-Quan; Ma, Lei; Zhang, Chi; Zhou, Wen-Jie; Lu, Ming

    2017-10-01

    We report to apply Al nanoparticles (NPs) to enhance the photovoltaic response of crystalline- or c-Si solar cell from the ultraviolet (UV) throughout the visible and near infrared (NIR) regimes. Al NPs were induced by solid thermal annealing and embedded in a SiO2 layer that was to passivate the front side of solar cell. Upon the excitation of surface plasmons (SPs) on the Al NPs under light illumination, an enhancement of broadband absorption of the solar cell was observed. The incorporation of Al NPs led to a relative 13.8% increase in photoelectric conversion efficiency of c-Si solar cell, and an external quantum efficiency enhancement from the UV throughout the visible and NIR regimes. The improvement of c-Si solar cell performance was attributed to both effects of absorption and scattering by SPs.

  1. Side chain engineering of poly-thiophene and its impact on crystalline silicon based hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zellmeier, M.; Rappich, J.; Nickel, N. H. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Silicon Photovoltaics, Kekuléstr. 5, 12489 Berlin (Germany); Klaus, M.; Genzel, Ch. [Department of Microstructure and Residual Stress Analysis, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Janietz, S. [Department of Polymer Electronics, Fraunhofer Institute for Applied Polymer Research, Geiselbergstr. 69, 14476 Potsdam (Germany); Frisch, J.; Koch, N. [Humboldt Universität zu Berlin, Brook-Taylor-Straße 6, 12489 Berlin (Germany)

    2015-11-16

    The influence of ether groups in the side chain of spin coated regioregular polythiophene derivatives on the polymer layer formation and the hybrid solar cell properties was investigated using electrical, optical, and X-ray diffraction experiments. The polymer layers are of high crystallinity but the polymer with 3 ether groups in the side chain (P3TOT) did not show any vibrational fine structure in the UV-Vis spectrum. The presence of ether groups in the side chains leads to better adhesion resulting in thinner and more homogeneous polymer layers. This, in turn, enhances the electronic properties of the planar c-Si/poly-thiophene hybrid solar cell. We find that the power conversion efficiency increases with the number of ether groups in the side chains, and a maximum power conversion efficiency of η = 9.6% is achieved even in simple planar structures.

  2. Ab initio density functional theory investigation of crystalline bundles of polygonized single-walled silicon carbide nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Moradian, Rostam; Behzad, Somayeh; Chegel, Raad [Physics Department, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of)], E-mail: moradian.rostam@gmail.com

    2008-11-19

    By using ab initio density functional theory, the structural characterizations and electronic properties of two large-diameter (13, 13) and (14, 14) armchair silicon carbide nanotube (SiCNT) bundles are investigated. Full structural optimizations show that the cross sections of these large-diameter SiCNTs in the bundles have a nearly hexagonal shape. The effects of inter-tube coupling on the electronic dispersions of large-diameter SiCNT bundles are demonstrated. By comparing the band structures of the triangular lattices of (14, 14) SiCNTs with nearly hexagonal and circular cross sections we found that the polygonization of the tubes in the bundle leads to a further dispersion of the occupied bands and an increase in the bandgap by 0.18 eV.

  3. Ab initio density functional theory investigation of crystalline bundles of polygonized single-walled silicon carbide nanotubes.

    Science.gov (United States)

    Moradian, Rostam; Behzad, Somayeh; Chegel, Raad

    2008-11-19

    By using ab initio density functional theory, the structural characterizations and electronic properties of two large-diameter (13, 13) and (14, 14) armchair silicon carbide nanotube (SiCNT) bundles are investigated. Full structural optimizations show that the cross sections of these large-diameter SiCNTs in the bundles have a nearly hexagonal shape. The effects of inter-tube coupling on the electronic dispersions of large-diameter SiCNT bundles are demonstrated. By comparing the band structures of the triangular lattices of (14, 14) SiCNTs with nearly hexagonal and circular cross sections we found that the polygonization of the tubes in the bundle leads to a further dispersion of the occupied bands and an increase in the bandgap by 0.18 eV.

  4. Dislocation density analyses of multi-crystalline silicon during the directional solidification process with bottom grooved furnace

    Science.gov (United States)

    Karuppasamy, P.; Srinivasan, M.; Aravinth, K.; Ramasamy, P.

    2016-05-01

    A transient global model was used to investigate the effect of bottom grooved furnace upon the directional solidification (DS) process of multicrystalline silicon (mc-Si). The computations were carried out on a 2D axisymmetric model using the finite volume method. The temperature distribution, crystal-melt (c-m) interface and dislocation density were simulated. The modified heat exchanger block system was used for controlling the temperature gradient at the bottom of the crucible. The obtained results shows convex shape of the c-m interface. The dislocation density was reduced while using the bottom grooved furnace. This work was carried out for the different groove of radius 30 and 60 mm of the heat exchanger block.

  5. High temperature luminescence of Dy3+ in crystalline silicon in the optical communication and eye-safe spectral regions.

    Science.gov (United States)

    Lourenço, M A; Mustafa, Z; Ludurczak, W; Wong, L; Gwilliam, R M; Homewood, K P

    2013-09-15

    We report on photoluminescence in the 1.3 and 1.7 μm spectral ranges in silicon doped with dysprosium. This is attributed to the Dy3+ internal transitions between the second Dy3+ excited state and the ground state, and between the third Dy3+ excited state and the ground state. Luminescence is achieved by Dy implantation into Si substrates codoped with boron, to form dislocation loops, and show a strong dependence on fabrication process. The spectra consist of several sharp lines with the strongest emission at 1736 nm, observed up to 200 K. No Dy3+ luminescence is observed in samples without B codoping, showing the paramount importance of dislocation loops to enable the Dy emission.

  6. Effect of dispersed hydrophilic silicon dioxide nanoparticles on batch adsorption of benzoic acid from aqueous solution using modified natural vermiculite: An equilibrium study

    Directory of Open Access Journals (Sweden)

    Ehsan Sadeghi Pouya

    2016-10-01

    Full Text Available The equilibrium adsorption of benzoic acid from an aqueous medium on a natural vermiculite-based adsorbent was studied in the presence and absence of hydrophilic silicon dioxide nanoparticles in batchwise mode. The adsorbent was prepared through grinding natural vermiculite in a laboratory vibratory disk mill and the surfactant modification of ground vermiculite by cetyltrimethylammonium bromide, subsequently. The equilibrium isotherm in the presence and absence of nanoparticles was experimentally obtained and the equilibrium data were fitted to the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models. The results indicated that the dispersion of silicon dioxide nanoparticles at optimum concentration in the liquid phase remarkably increases the removal efficiency. Furthermore, it yields a more favorable equilibrium isotherm and changes the compatibility of equilibrium data from the Langmuir and Temkin equations to just the Langmuir equation. A quadratic polynomial model predicting the equilibrium adsorbent capacity in the presence of nanoparticles as a function of the adsorbate and initial nanoparticle concentrations was successfully developed using the response surface methodology based on the rotatable central composite design. A desirability function was used in order to optimize the values of all variables, independent and dependent ones, simultaneously.

  7. Short-circuit current density imaging of crystalline silicon solar cells via lock-in thermography: Robustness and simplifications

    Energy Technology Data Exchange (ETDEWEB)

    Fertig, Fabian, E-mail: fabian.fertig@ise.fraunhofer.de; Greulich, Johannes; Rein, Stefan [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, D-79110 Freiburg (Germany)

    2014-11-14

    Spatially resolved determination of solar cell parameters is beneficial for loss analysis and optimization of conversion efficiency. One key parameter that has been challenging to access by an imaging technique on solar cell level is short-circuit current density. This work discusses the robustness of a recently suggested approach to determine short-circuit current density spatially resolved based on a series of lock-in thermography images and options for a simplified image acquisition procedure. For an accurate result, one or two emissivity-corrected illuminated lock-in thermography images and one dark lock-in thermography image have to be recorded. The dark lock-in thermography image can be omitted if local shunts are negligible. Furthermore, it is shown that omitting the correction of lock-in thermography images for local emissivity variations only leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition of one image only is sufficient to generate a meaningful map of short-circuit current density. Beyond that, this work illustrates the underlying physics of the recently proposed method and demonstrates its robustness concerning varying excitation conditions and locally increased series resistance. Experimentally gained short-circuit current density images are validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

  8. The microstructure matters: breaking down the barriers with single crystalline silicon as negative electrode in Li-ion batteries.

    Science.gov (United States)

    Sternad, M; Forster, M; Wilkening, M

    2016-08-17

    Silicon-based microelectronics forms a major foundation of our modern society. Small lithium-ion batteries act as the key enablers of its success and have revolutionised portable electronics used in our all everyday's life. While large-scale LIBs are expected to help establish electric vehicles, on the other end of device size chip-integrated Si-based μ-batteries may revolutionise microelectronics once more. In general, Si is regarded as one of the white hopes since it offers energy densities being ten times higher than conventional anode materials. The use of monocrystalline, wafer-grade Si, however, requires several hurdles to be overcome since it its volume largely expands during lithiation. Here, we will show how 3D patterned Si wafers, prepared by the sophisticated techniques from semiconductor industry, are to be electrochemically activated to overcome these limitations and to leverage their full potential being reflected in stable charge capacities (>1000 mAhg(-1)) and high Coulomb efficiencies (98.8%).

  9. Kinetics of the permanent deactivation of the boron-oxygen complex in crystalline silicon as a function of illumination intensity

    Science.gov (United States)

    Steckenreiter, Verena; Walter, Dominic C.; Schmidt, Jan

    2017-03-01

    Based on contactless carrier lifetime measurements performed on p-type boron-doped Czochralski-grown silicon (Cz-Si) wafers, we examine the rate constant Rde of the permanent deactivation process of the boron-oxygen-related defect center as a function of the illumination intensity I at 170°C. While at low illumination intensities, a linear increase of Rde on I is measured, at high illumination intensities, Rde seems to saturate. We are able to explain the saturation by assuming that Rde increases proportionally with the excess carrier concentration Δ n and take the fact into account that at sufficiently high illumination intensities, the carrier lifetime decreases with increasing Δ n and hence the slope of Δ n (I) decreases, leading to an apparent saturation. Importantly, on low-lifetime Cz-Si samples no saturation of the deactivation rate constant is observed for the same illumination intensities, proving that the deactivation is stimulated by the presence of excess electrons and not directly by the photons.

  10. The microstructure matters: breaking down the barriers with single crystalline silicon as negative electrode in Li-ion batteries

    Science.gov (United States)

    Sternad, M.; Forster, M.; Wilkening, M.

    2016-08-01

    Silicon-based microelectronics forms a major foundation of our modern society. Small lithium-ion batteries act as the key enablers of its success and have revolutionised portable electronics used in our all everyday’s life. While large-scale LIBs are expected to help establish electric vehicles, on the other end of device size chip-integrated Si-based μ-batteries may revolutionise microelectronics once more. In general, Si is regarded as one of the white hopes since it offers energy densities being ten times higher than conventional anode materials. The use of monocrystalline, wafer-grade Si, however, requires several hurdles to be overcome since it its volume largely expands during lithiation. Here, we will show how 3D patterned Si wafers, prepared by the sophisticated techniques from semiconductor industry, are to be electrochemically activated to overcome these limitations and to leverage their full potential being reflected in stable charge capacities (>1000 mAhg–1) and high Coulomb efficiencies (98.8%).

  11. PECVD-ONO: A New Deposited Firing Stable Rear Surface Passivation Layer System for Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    M. Hofmann

    2008-01-01

    Full Text Available A novel plasma-enhanced chemical vapour deposited (PECVD stack layer system consisting of a-SiOx:H, a-SiNx:H, and a-SiOx:H is presented for silicon solar cell rear side passivation. Surface recombination velocities below 60 cm/s (after firing and below 30 cm/s (after forming gas anneal were achieved. Solar cell precursors without front and rear metallisation showed implied open-circuit voltages Voc values extracted from quasi-steady-state photoconductance (QSSPC measurements above 680 mV. Fully finished solar cells with up to 20.0% energy conversion efficiency are presented. A fit of the cell's internal quantum efficiency using software tool PC1D and a comparison to a full-area aluminium-back surface field (Al-BSF and thermal SiO2 is shown. PECVD-ONO was found to be clearly superior to Al-BSF. A separation of recombination at the metallised and the passivated area at the solar cell's rear is presented using the equations of Fischer and Kray. Nuclear reaction analysis (NRA has been used to evaluate the hydrogen depth profile of the passivation layer system at different stages.

  12. Effect of Added Salts or Polyols on the Cloud Point and the Liquid-Crystalline Structures of Polyoxyethylene-Modified Silicone.

    Science.gov (United States)

    Iwanaga; Kunieda

    2000-07-15

    The effect of added salts (NaCl, Na(2)SO(4), and NaSCN) or polyols (glycerin (Gly), 1,3-butanediol (1,3-BD), ethylene glycol (EG), and polyethylene glycol (PEG400)) on the hexagonal liquid-crystalline structure of polyoxyethylene-modified silicone was investigated by means of small angle X-ray scattering (SAXS). The effective cross-sectional area of the lipophilic part of the aggregate, a(s), in the hexagonal phase decreases upon the addition of salts, on one hand, lowering the cloud point in the dilute aqueous siloxane surfactant solutions. On the other hand, if added salt raises the cloud point, the a(s) increases. Similar results were obtained in the case of the addition of polyols. Since the a(s) mainly depends on the EO chain length, the above results are direct evidence that the hydration or dehydration of the EO chain is affected by these additives. The static fluorescence probe method was applied to the Gly and 1,3-BD systems using 8-anilino-1-naphthalene-sulfonic acid, ANS, to know the change in hydration of the EO chains. In the Gly system, the hydration of the EO chain monotonically decreases whereas 1,3-BD first increases the hydration and then decreases it at high 1,3-BD content. These results are very consistent with the SAXS and cloud temperature results. Copyright 2000 Academic Press.

  13. Variation in the Optical Properties of the SiC-SiO2 Composite Antireflection Layer in Crystalline Silicon Solar Cells by Annealing

    Science.gov (United States)

    Jannat, Azmira; Li, Zhen Yu; Akhter, M. Shaheer; Yang, O.-Bong

    2017-07-01

    This study showed the effects of annealing on a sol-gel-derived SiC-SiO2 composite antireflection (AR) layer and investigated the optical and photovoltaic properties of crystalline silicon (Si) solar cells. The SiC-SiO2 composite AR coating showed a considerable decrease in reflectance from 7.18% to 3.23% at varying annealing temperatures of 450-800°C. The refractive indices of the SiC-SiO2 composite AR layer were tuned from 2.06 to 2.45 with the increase in annealing temperature. The analysis of the current density-voltage characteristics indicated that the energy conversion efficiencies of the fabricated Si solar cells gradually increased from 16.99% to 17.73% with increasing annealing temperatures of 450-800°C. The annealing of the SiC-SiO2 composite AR layer in Si solar cells was crucial to improving the optical, morphological, and photovoltaic properties.

  14. Research on Matching of Sintering Process of Crystalline Silicon Solar Cells%晶体硅太阳能电池烧结匹配性研究

    Institute of Scientific and Technical Information of China (English)

    杨达伟; 高华; 杨乐

    2013-01-01

      良好的烧结能够极大地提升太阳能电池的转换效率。通过理论分析太阳能电池烧结后各参数的变化情况,预测烧结的状态以及烧结的调节方向,进而通过实验来验证理论分析,从而得到工业生产中晶硅电池烧结匹配优化方法。通过不断对烧结的优化,从而达到了改善烧结效果,提升电池片功率的目的。%Good sintering can enhance the conversion efficiency of solar cells. Through theoretical analysis of the parameters changes of the solar cell after sintering, and predict the state of the sintering and sintering direction of regulation, and then by doing experiments to verify the theoretical analysis, result in matching optimization method of the industrial production of crystalline silicon cells sintering. Through continuous optimization of the sintering, achieve the purpose of improving sintering effect, and enhance the conversion efficiency of solar cells.

  15. Relation of lifetime to surface passivation for atomic-layer-deposited Al{sub 2}O{sub 3} on crystalline silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Joon [Graduate School of Energy Science and Technology, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Song, Hee Eun, E-mail: hsong@kier.re.kr [Photovoltaic Center, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Chang, Hyo Sik, E-mail: hschang@cnu.ac.kr [Graduate School of Energy Science and Technology, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

    2015-03-15

    Highlights: • We investigated the relation of potassium contamination on Si solar wafer to lifetime. • We deposited Al{sub 2}O{sub 3} layer by atomic layer deposition (ALD) on Si solar wafer after several cleaning process. • Potassium can be left on Si surface by incomplete cleaning process and degrade the Al{sub 2}O{sub 3} passivation quality. - Abstract: We investigated the relation of potassium contamination on a crystalline silicon (c-Si) surface after potassium hydroxide (KOH) etching to the lifetime of the c-Si solar cell. Alkaline solution was employed for saw damage removal (SDR), texturing, and planarization of a textured c-Si solar wafer prior to atomic layer deposition (ALD) Al{sub 2}O{sub 3} growth. In the solar-cell manufacturing process, ALD Al{sub 2}O{sub 3} passivation is utilized to obtain higher conversion efficiency. ALD Al{sub 2}O{sub 3} shows excellent surface passivation, though minority carrier lifetime varies with cleaning conditions. In the present study, we investigated the relation of potassium contamination to lifetime in solar-cell processing. The results showed that the potassium-contaminated samples, due to incomplete cleaning of KOH, had a short lifetime, thus establishing that residual potassium can degrade Al{sub 2}O{sub 3} surface passivation.

  16. Decoupling crystalline volume fraction and V{sub OC} in microcrystalline silicon pin solar cells by using a {mu}c-Si:F:H intrinsic layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q.; Johnson, E.V.; Djeridane, Y.; Abramov, A.; Roca i Cabarrocas, P. [LPICM-CNRS, Ecole Polytechnique, Palaiseau (France)

    2008-08-15

    Microcrystalline silicon thin film pin solar cells with a highly crystallized intrinsic {mu}c-Si:F:H absorber were prepared by RF-plasma enhanced chemical vapour deposition using SiF{sub 4} as the gas precursor. The cells were produced with a vacuum break between the doped layer and intrinsic layer depositions, and the effect of different subsequent interface treatment processes was studied. The use of an intrinsic {mu}c-Si:H p/i buffer layer before the first air break increased the short circuit current density from 22.3 mA/cm{sup 2} to 24.7 mA/cm{sup 2}. However, the use of a hydrogen-plasma treatment after both air breaks without an interface buffer layer improved both the open circuit voltage and the fill factor. Although the material used for the absorber layer showed a very high crystalline fraction and thus an increased spectral response at long wavelengths, an open-circuit voltage (V{sub OC}) of 0.523 V was nevertheless observed. Such a value of V{sub OC} is higher than is typically obtained in devices that employ a highly crystallized absorber as reported in the literature (see abstract figure). Using a hydrogen-plasma treatment, a single junction {mu}c-Si:F:H pin solar cell with an efficiency of 8.3% was achieved. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Silicon molybdenum blue spectrophotometric determination of silicon dioxide in arsenic trioxide%硅钼蓝分光光度法测定三氧化二砷中二氧化硅

    Institute of Scientific and Technical Information of China (English)

    谢辉; 赖心; 黄葡英

    2011-01-01

    In this study, hydrochloric acid was added into arsenic trioxide to remove arsenic by heating. The obtained residual was dissolved with sodium hydroxide. After acidification with nitric acid,silicon could form silicon molybdenum yellow complex with molybdate at pH 0. 9 using ammonium molybdate as color developer. With sulfuric acid increase the acidity, the complex was reduced to silicon molybdenum blue complex by ascorbic acid. The content of silicon dioxide was determined by spectrophotometry. The maximum absorption wavelength of silicon molybdenum blue complex was 813 nm. The relative standard deviations (RSD, n=6) were 1. 6 %-1. 9%. The determination results of this method were consistent with those obtained by ICP-AES.%研究了在三氧化二砷中加入盐酸,加热除砷,所得残渣用氢氧化钠溶解,硝酸酸化后,以钼酸铵为显色剂,在pH 0.9条件下,硅与钼酸盐形成硅钼黄络合物,用硫酸提高酸度,以抗坏血酸为还原剂,使硅形成稳定的硅钼蓝络合物,采用分光光度法测定其中的二氧化硅含量.硅钼蓝络合物最大吸收波长位于813 nm处.本法相对标准偏差(RSD)为1.6%~1.9%(n=6),测定结果与.ICP-AES法的结果相一致.

  18. Lithographically patterned silicon nanostructures on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Megouda, Nacera [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Universite Lille1, Parc de la Haute Borne, 50 Avenue de Halley-BP 70478, 59658 Villeneuve d' Ascq and Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, CNRS-8520), Cite Scientifique, Avenue Poincare-B.P. 60069, 59652 Villeneuve d' Ascq (France); Faculte des Sciences, Universite Mouloud Mammeri, Tizi-Ouzou (Algeria); Unite de Developpement de la Technologie du Silicium (UDTS), 2 Bd. Frantz Fanon, B.P. 140 Alger-7 merveilles, Alger (Algeria); Piret, Gaeelle; Galopin, Elisabeth; Coffinier, Yannick [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Universite Lille1, Parc de la Haute Borne, 50 Avenue de Halley-BP 70478, 59658 Villeneuve d' Ascq and Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, CNRS-8520), Cite Scientifique, Avenue Poincare-B.P. 60069, 59652 Villeneuve d' Ascq (France); Hadjersi, Toufik, E-mail: hadjersi@yahoo.com [Unite de Developpement de la Technologie du Silicium (UDTS), 2 Bd. Frantz Fanon, B.P. 140 Alger-7 merveilles, Alger (Algeria); Elkechai, Omar [Faculte des Sciences, Universite Mouloud Mammeri, Tizi-Ouzou (Algeria); and others

    2012-06-01

    The paper reports on controlled formation of silicon nanostructures patterns by the combination of optical lithography and metal-assisted chemical dissolution of crystalline silicon. First, a 20 nm-thick gold film was deposited onto hydrogen-terminated silicon substrate by thermal evaporation. Gold patterns (50 {mu}m Multiplication-Sign 50 {mu}m spaced by 20 {mu}m) were transferred onto the silicon wafer by means of photolithography. The etching process of crystalline silicon in HF/AgNO{sub 3} aqueous solution was studied as a function of the silicon resistivity, etching time and temperature. Controlled formation of silicon nanowire arrays in the unprotected areas was demonstrated for highly resistive silicon substrate, while silicon etching was observed on both gold protected and unprotected areas for moderately doped silicon. The resulting layers were characterized using scanning electron microscopy (SEM).

  19. Emitter study of front junction back contact crystalline silicon solar cells%前结背接触晶硅太阳电池发射区研究

    Institute of Scientific and Technical Information of China (English)

    周涛; 陆晓东; 吴元庆; 刘兴辉; 吴春瑜

    2015-01-01

    利用Silvaco-TCAD仿真软件全面系统地分析了发射区表面浓度(cE)、结深(xj)及发射区覆盖比率(EF)对P型前结背接触晶硅太阳电池输出特性的影响。结果表明:基于常规低成本P型晶硅衬底(利用直拉法生长,电阻率为1.5Ω·cm,少子寿命为10μs)的前结背接触太阳电池,其上表面发射区表面浓度及结深对太阳电池的输出特性产生显著影响。上表面发射区表面浓度和结深越大,短波入射光外量子效率越小。当上表面发射区表面浓度为1×1019 cm–3,结深为0.2μm时,电池效率高达20.72%。侧面和下表面发射区表面浓度及结深对太阳电池输出特性的影响较小。但侧面和下表面发射区覆盖比率对太阳电池的输出特性产生显著影响。侧面和下表面发射区覆盖比率越大,太阳电池外量子效率和转换效率越高。%By using Silvaco-TCAD simulation software, the influences of the emitter surface concentration (cE), the junction depth (xj) and the emitter fraction (EF) on the output characteristics of P-type front junction back contact crystalline silicon solar cell was analyzed. The results show that the upper surface emitter surface concentration and the junction depth of the front junction back contact crystalline silicon solar cell based on conventional low-cost P-type silicon substrate (CZ growth method, the resistivity is 1.5Ω·cm, the minority carrier life is 10μs) have a noticeable effect on output characteristics of solar cells. The higher the upper surface emitter surface concentration, the deeper the junction depth, the lower the short wavelength incident light external quantum efficiency. When the upper surface emitter surface concentration is 1×1019 cm–3 and the junction depth is 0.2μm,the solar cell conversion efficiency reaches 20.72%. The side-surface and under-surface emitter surface concentration and the junction depth have a slight effect on output

  20. Concentrator bifacial crystalline silicon solar cells with multi-wire metallization attached to TCO layers using transparent conductive polymers

    Science.gov (United States)

    Untila, Gennady; Chebotareva, Alla; Kost, Tatiana; Salazkin, Sergei; Shaposhnikova, Vera; Shvarts, Maxim

    2017-09-01

    Replacing expensive silver with inexpensive copper for the metallization of silicon wafer solar cells can lead to substantial reductions in material costs associated with cell production. A promising approach is the use of multi-wire design. This technology uses many wires in the place of busbars, and the copper wires are "soldered" during the low-temperature lamination process to the fingers (printed or plated) or to the transparent conductive oxide (TCO) layer, e.g. in the case of the α-Si/c-Si heterojunction cells. Here we describe a solar cell design in which wires are attached to TCO layers using transparent conductive polymer (TCP) films. To this end, we have synthesized a number of thermoplastics, poly(arylene ether ketone) copolymers (co-PAEKs), containing phthalide in their main chain. The fraction of phthalide-containing units in the copolymers was p = 3, 5, 15, and 50 mol %. With increasing p, the peak strain temperature of the co-PAEKs rises from 205 to 290 °C and their optical band gap and refractive index increase from 3.12 to 3.15 eV and from 1.6 to 1.614, respectively. The copolymers have a negligible absorption coefficient in the wavelength range 400- 1100 nm. When exposed to an excess pressure of 1 atm or above, co-PAEK films less than 30 µm in thickness undergo a transition from a dielectric to a conductive state. The resistivity (ρC) of wire/TCP/TCO (ITO = In2O3:Sn and IFO = In2O3:F) contacts ranges from 0.37 to 1.43 mΩ cm2. The polymer with the highest phthalide content (p = 50 mol %) has the lowest ρC. The average work of adhesion per unit area determined by pulling off the wires from the polymer surface depends on both the phthalide content of the co-PAEKs and their reduced viscosity, ranging from 14.3 to 43.5 N/cm. The highest value was obtained for the co-PAEK with p = 50 mol %. We have fabricated low-concentration bifacial IFO/(n+pp+)Cz-Si/ITO solar cells with a wire contact grid attached to IFO and ITO using a co-PAEK film. The

  1. FEM numerical analysis of excimer laser induced modification in alternating multi-layers of amorphous and nano-crystalline silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.es [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Martin, E. [Dpto. Mecanica, Maquinas, Motores Termicos y Fluidos, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Stefanov, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Alpuim, P. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Chiussi, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer nc-Si:H is a material with growing importance for a large-area of nano-electronic, photovoltaic or biomedical devices. Black-Right-Pointing-Pointer UV-ELA technique causes a rapid heating that provokes the H{sub 2} desorption from the Si surface and bulk material. Black-Right-Pointing-Pointer Next, diffusion of P doped nc-Si films and eventually, for high energy densities would be possible to reach the melting point. Black-Right-Pointing-Pointer These multilayer structures consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) films deposited on SiO{sub 2}. Black-Right-Pointing-Pointer To optimize parameters involved in this processing, FEM numerical analysis of multilayer structures have been performed. Black-Right-Pointing-Pointer The numerical results are compared with exhaustive characterization of the experimental results. - Abstract: UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193 nm radiation with 25

  2. 氧化铝钝化在晶体硅太阳电池中的应用%Al2O3 Passivation for Crystalline Silicon Solar Cells

    Institute of Scientific and Technical Information of China (English)

    吴大卫; 贾锐; 武德起; 丁武昌; 陈伟; 陈晨; 岳会会; 刘新宇; 陈宝钦

    2011-01-01

    Firstly, the development of the aluminum oxide (Al2O3) passivation technology is reviewed, and the preparation methods are summarized. Then, the material properties and passivation mechanisms of the Al2O3 films are described in detail. It is pointed out that the Al2O3 films have excellent field-effect passivation property and chemical passivation property. Thus, the Al2O3 films can be well applied to the passivation of lowly doped and highly doped p-type silicon surfaces. Besides that, the Al2O3 films are of good heat stability, satisfying the requirement of screen-printed solar cells. Finally, the latest studies of the Al2O3 films passivation technology applied to crystalline silicon solar cells are presented, the application problems of Al2O3 films for the industry production are pointed out, and some effective solutions are proposed in the light of these problems.%首先,回顾了氧化铝钝化技术的发展历程,对制备氧化铝钝化薄膜的手段进行了总结,并且详细描述了氧化铝的材料性质和钝化的机理.其次,指出氧化铝薄膜的优点在于优异的场效应钝化特性和良好的化学钝化性质,因此可以应用于低掺和高掺p型硅表面的钝化.此外,氧化铝薄膜及其叠层还具有良好的热稳定性,符合丝网印刷太阳电池的要求.最后,总结了氧化铝薄膜钝化技术在晶体硅太阳电池中的最新研究动态,指出氧化铝钝化薄膜用于工业生产中存在的问题,并针对这些问题提出了有效的解决方案.

  3. Innovative technologies for emitter formation of crystalline silicon solar cells using in-line diffusion; Innovative Technologien zur Emittererzeugung fuer kristalline Silizium-Solarzellen mittels Durchlaufdiffusion

    Energy Technology Data Exchange (ETDEWEB)

    Voyer, Catherine

    2009-04-20

    An in-line emitter formation process for crystalline silicon solar cells was developed. The wafers were coated at room temperature with dilute phosphoric acid (2.5 w/w% in water) using ultrasonic spraying and then heated up to temperatures around 900 C in a metal-contamination-free in-line furnace. In the first zones of the furnace, a phosphosilicate glass (PSG) is formed on the silicon surface and serves as the doping source. The PSG thickness was adjusted by varying the flow rate of dilute phosphoric acid to the spray nozzle and took on values appropriate for emitter formation, in the range of {proportional_to}40-120 nm. A surfactant mixture was added to the dilute phosphoric acid in order to obtain complete wetting of the silicon surface. The mixture, which was composed of a hydrocarbon surfactant and of a fluorosurfactant, achieved better wetting properties than would be possible when using only one of the two surfactants. The spray solution containing only the hydrocarbon surfactant achieved a faster drop flattening, while the spray solution containing only the fluorosurfactant achieved a lower static surface tension. The mixture allowed for a combination of these desired properties: The drops coalesced together sufficiently rapidly (before drying) on the silicon surface to form a complete dopant source liquid layer and this layer remains sufficiently homogeneous during the layer drying. The sprayed-on layer is thicker ({proportional_to}15 microns) than the height of the surface texture ({proportional_to}5-10 microns). The liquid strives for a state of equilibrium, a convex meniscus. The topography of the liquid surface at the time at which the increase in viscosity puts an end to the liquid flow is reflected in the topography of the PSG thickness. The corresponding variations in sheet resistance across a wafer are sufficiently small for solar cells. Furthermore, the liquid layer conforms itself, during the drying, to the surface texture on a microscopic scale

  4. Innovative technologies for emitter formation of crystalline silicon solar cells using in-line diffusion; Innovative Technologien zur Emittererzeugung fuer kristalline Silizium-Solarzellen mittels Durchlaufdiffusion

    Energy Technology Data Exchange (ETDEWEB)

    Voyer, Catherine

    2009-04-20

    An in-line emitter formation process for crystalline silicon solar cells was developed. The wafers were coated at room temperature with dilute phosphoric acid (2.5 w/w% in water) using ultrasonic spraying and then heated up to temperatures around 900 C in a metal-contamination-free in-line furnace. In the first zones of the furnace, a phosphosilicate glass (PSG) is formed on the silicon surface and serves as the doping source. The PSG thickness was adjusted by varying the flow rate of dilute phosphoric acid to the spray nozzle and took on values appropriate for emitter formation, in the range of {proportional_to}40-120 nm. A surfactant mixture was added to the dilute phosphoric acid in order to obtain complete wetting of the silicon surface. The mixture, which was composed of a hydrocarbon surfactant and of a fluorosurfactant, achieved better wetting properties than would be possible when using only one of the two surfactants. The spray solution containing only the hydrocarbon surfactant achieved a faster drop flattening, while the spray solution containing only the fluorosurfactant achieved a lower static surface tension. The mixture allowed for a combination of these desired properties: The drops coalesced together sufficiently rapidly (before drying) on the silicon surface to form a complete dopant source liquid layer and this layer remains sufficiently homogeneous during the layer drying. The sprayed-on layer is thicker ({proportional_to}15 microns) than the height of the surface texture ({proportional_to}5-10 microns). The liquid strives for a state of equilibrium, a convex meniscus. The topography of the liquid surface at the time at which the increase in viscosity puts an end to the liquid flow is reflected in the topography of the PSG thickness. The corresponding variations in sheet resistance across a wafer are sufficiently small for solar cells. Furthermore, the liquid layer conforms itself, during the drying, to the surface texture on a microscopic scale

  5. Evolvement of cell-substrate interaction over time for cells cultivated on a 3-aminopropyltriethoxysilane (γ-APTES) modified silicon dioxide (SiO2) surface

    Science.gov (United States)

    Hsu, Chung-Ping; Hsu, Po-Yen; Wu, You-Lin; Hsu, Wan-Yun; Lin, Jing-Jenn

    2012-09-01

    Since cell-substrate interaction is directly related to the traction force of the cell, the cell property can be judged from the imprint it leaves on the soft substrate surface onto which the cell is cultured. In this letter, the evolvement of the cell-substrate interaction over time was observed by cultivating cells on a 3-aminopropyltriethoxysilane (γ-APTES) modified silicon dioxide (SiO2) surface for different periods of time. The cell-substrate interaction property as a function of time can then be found from the post-cell-removal surface morphology profiles determined by atomic force microscopy (AFM). Different surface morphology profiles were found between normal cells and cancer cells. It was found that the cancer cells tend to form deeper trenches along the circumference of the imprints, while the normal cells do not. In addition, our results indicated that normal cells involve cell-substrate interaction mechanisms that are different from those for cancer cells.

  6. Rapid Determination of Silicon Dioxide Content in Copper Concentrate%铜精矿中二氧化硅含量的快速测定

    Institute of Scientific and Technical Information of China (English)

    戚月花; 张淑玲; 李先和; 万双; 崔鲁

    2016-01-01

    Content of silicon dioxide in copper concentrate was determined by alkali fused silica molybdenum blue spectrophotometric method. It was discussed about the solution conditions, absorption wavelength, solution acidity, water bath time, color and coexisting ions interference conditions on the influence of the absorbance. Sodium hydroxide as solvent,melting for 15 min at 680℃,melting sample effect was the best. The wavelength was selected according to the content of silicon dioxide in sample, detection wavelength was set of 810 nm for the silicon dioxide content of less than 1%, detection wavelength was set of 650 nm for the content of 1%–15%;the color effect was the best with hydrochloric acid solution of 0.15–0.20 mol/L, water bath heating of 60 s,color time of 15 min. Ammonium ferric sulfate was used as a reducing agent. The recoveries of standard addition was between 94.8%–98.8%, the relative standard deviations of five independent sample determination results were 0.26%–4.48%(n=11), the results in standard sample were consistent with the certified values. The method is simple, rapid, accurate and suitable for the determination of silicon dioxide content in the copper concentrate.%采用碱熔样硅钼蓝分光光度法测定铜精矿中二氧化硅的含量。讨论了熔融条件、吸收波长、溶液酸度、水浴加热时间、显色时间以及共存离子干扰等条件对测定结果的影响。确定以氢氧化钠为熔剂,在680℃熔融15 min,熔样效果最佳;根据样品中二氧化硅的含量选择波长,当二氧化硅含量小于1%时,选用810 nm为分析波长,二氧化硅含量为1%~15%时,选用650 nm为分析波长;在酸度为0.15~0.20 mol/L盐酸溶液中,水浴加热60 s,显色15 min,显色效果为最佳。使用硫酸亚铁铵作为还原剂。方法的加标回收率在94.8%~98.8%之间,5个样品独立测定结果的相对标准偏差为0.26%~4.48%(n=11),标准样品测定结果与标

  7. Determination of Silicon Dioxide in Fluorspar by Potassium Fluorosilicate Volumetry%浅淡氟硅酸钾容量法检测萤石二氧化硅

    Institute of Scientific and Technical Information of China (English)

    柳丽娜; 张翠芬; 韩娟伟; 朱秀玉

    2011-01-01

    从检测数据精度和检测效率两方面说明了氟硅酸钾容量法在检测萤石二氧化硅方面的优势。详细介绍了氟硅酸钾容量法的分析化学原理,最后从检测实践方面详细阐述了试验过程中的注意事项,从而有利于更快、更好的进行萤石二氧化硅的检测。%The advantages of determining the silicon dioxide content in fluorspar by potassium fluorosilicate volumetry are described in terms of test data accuracy and testing efficiency, and the attentions to be paid in actual tests are stated in detail to help to make the determination quicker and better.

  8. Technology development for crystalline silicon thin-film solar cells (TEKSI). Final report; Technologieentwicklung fuer kristalline Silizium-Duennschicht-Solarzellen (TEKSI). Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Wettling, W.; Hurrle, A.; Bau, S.; Eyer, A.; Haas, F.; Huljic, D.; Kieliba, T.; Lautenschlager, H.; Luedemann, R.; Lutz, F.; Preu, R.; Reber, S.; Rentsch, J.; Schaefer, S.; Schetter, C.; Schillinger, N.; Warta, W.; Zimmermann, W.

    2002-10-01

    The results of a project aimed at the development of crystalline solar wafers are presented. All process stages were reviewed in detail with a view to industrial fabrication. This included also the further development of machinery, e.g. for selective zone melting recrystallisation, CVD silicon deposition, and characterisation of deposited films and solar cells. Not all the envisaged goals were achieved. For example, efficiencies up to 17.6 percent were possible on direct epitactic, highly doped CZ-Si substrates and with a high-efficiency process, but the normal efficiencies of solar cells on SSP or on ceramic substrates were in the range of 8-11 percent. This underlines the need for further research on the development of appropriate substrates with reproducible properties. [German] Im vorliegenden Bericht werden die Ergebnisse eines mehrjaehrigen Projekts zur Entwicklung der kristallinen Silizium-Duennschichtsolarzelle (KSD-Solarzelle) vorgestellt. Die Arbeiten waren eine konsequente Fortsetzung der bereits in einem Vorgaengerprojekt (FKZ 0328986B) bearbeiteten Themen. Alle zur Herstellung solcher Solarzellen noetigen Prozessschritte im Rahmen des am Fraunhofer ISE verfolgten Hochtemperaturpfads wurden detailliert untersucht, insbesondere im Hinblick auf eine industrielle Fertigung. Ein wesentlicher Teil der Arbeiten befasste sich deshalb auch mit der Weiterentwicklung von Geraeten, so z. B. fuer die Zonenschmelzrekristallisation, fuer die Silizumabscheidung mittels CVD-Verfahren und fuer die Charakterisierung abgeschiedener Schichten und Solarzellen. Nicht alle der ehrgeizigen Projektziele konnten erreicht werden. Auf direkt epitaxierten, hochdotierten CZ-Si-Substraten konnten zwar mit einem High-Efficiency-Prozess Wirkungsgrade bis zu 17.6%, mit fertigungsrelevanter Siebdrucktechnologie bis 13% erzielt werden. Die Wirkungsgrade von Solarzellen auf SSP oder auf Keramiksubstraten lagen aber alle im Bereich von 8-11%. Dies zeigt deutlich, dass die Entwicklung

  9. High-temperature degradation in plasma-enhanced chemical vapor deposition Al{sub 2}O{sub 3} surface passivation layers on crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kühnhold, Saskia [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, D-79110 Freiburg (Germany); Freiburg Materials Research Center FMF, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Straße 21 (Germany); Saint-Cast, Pierre; Kafle, Bishal; Hofmann, Marc [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, D-79110 Freiburg (Germany); Colonna, Francesco [Freiburg Materials Research Center FMF, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Straße 21 (Germany); Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg (Germany); Zacharias, Margit [Department of Microsystems Engineering IMTEK, Albert-Ludwigs-Universität Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)

    2014-08-07

    In this publication, the activation and degradation of the passivation quality of plasma-enhanced chemical vapor deposited aluminum oxide (Al{sub 2}O{sub 3}) layers with different thicknesses (10 nm, 20 nm, and 110 nm) on crystalline silicon (c-Si) during long and high temperature treatments are investigated. As indicated by Fourier Transform Infrared Spectroscopy, the concentration of tetrahedral and octahedral sites within the Al{sub 2}O{sub 3} layer changes during temperature treatments and correlates with the amount of negative fixed charges at the Si/Al{sub 2}O{sub 3} interface, which was detected by Corona Oxide Characterization of Semiconductors. Furthermore, during a temperature treatment at 820 °C for 30 min, the initial amorphous Al{sub 2}O{sub 3} layer crystallize into the γ-Al{sub 2}O{sub 3} structure and was enhanced by additional oxygen as was proven by x-ray diffraction measurements and underlined by Density Functional Theory simulations. The crystallization correlates with the increase of the optical density up to 20% while the final Al{sub 2}O{sub 3} layer thickness decreases at the same time up to 26%. All observations described above were detected to be Al{sub 2}O{sub 3} layer thickness dependent. These observations reveal novel aspects to explain the temperature induced passivation and degradation mechanisms of Al{sub 2}O{sub 3} layers at a molecular level like the origin of the negative fixe charges at the Si/SiO{sub x}/Al{sub 2}O{sub 3} interface or the phenomena of blistering. Moreover, the crystal phase of Al{sub 2}O{sub 3} does not deliver good surface passivation due to a high concentration of octahedral sites leading to a lower concentration of negative fixed charges at the interface.

  10. Vertically-resolved profiles of mass concentrations and particle backscatter coefficients of Asian dust plumes derived from lidar observations of silicon dioxide.

    Science.gov (United States)

    Noh, Youngmin; Müller, Detlef; Shin, Sung-Kyun; Shin, Dongho; Kim, Young J

    2016-01-01

    This study presents a method to retrieve vertically-resolved profiles of dust mass concentrations by analyzing Raman lidar signals of silicon dioxide (quartz) at 546nm. The observed particle plumes consisted of mixtures of East Asian dust with anthropogenic pollution. Our method for the first time allows for extracting the contribution of the aerosol component "pure dust" contained in the aerosol type "polluted dust". We also propose a method that uses OPAC (Optical Properties of Aerosols and Clouds) and the mass concentrations profiles of dust in order to derive profiles of backscatter coefficients of pure dust in mixed dust/pollution plumes. The mass concentration of silicon dioxide (quartz) in the atmosphere can be estimated from the backscatter coefficient of quartz. The mass concentration of dust is estimated by the weight percentage (38-77%) of mineral quartz in Asian dust. The retrieved dust mass concentrations are classified into water soluble, nucleation, accumulation, mineral-transported and coarse mode according to OPAC. The mass mixing ratio of 0.018, 0.033, 0.747, 0.130 and 0.072, respectively, is used. Dust extinction coefficients at 550nm were calculated by using OPAC and prescribed number concentrations for each of the 5 components. Dust backscatter coefficients were calculated from the dust extinction coefficients on the basis of a lidar ratio of 45±3sr at 532nm. We present results of quartz-Raman measurements carried out on the campus of the Gwangju Institute of Science and Technology (35.10°N, 126.53°E) on 15, 16, and 21 March 2010.

  11. DIFFUSION PROCESS OF CRYSTALLINE SILICON SOLAR CELLS%晶体硅太阳电池扩散工艺研究

    Institute of Scientific and Technical Information of China (English)

    刘金虎; 徐征; 赵谡玲; 刘志平; 李栋才

    2012-01-01

    作为晶体硅太阳电池制作的心脏环节,扩散的效果也就是扩散后方块电阻的均匀性显得尤为重要.影响方块电阻均匀性的主要因素有:大小氮的流量、O2的流量、通源时间、再分布时间和中心温度.通过逐一改变这些因素,分析所得数据,得到一个能有效控制方块电阻大小、使方块电阻均匀性达到最佳的规律:大小氮流量的变化共同影响方块电阻均匀性;方块电阻大小的改变主要靠温度、时间、小氮的流量的改变来调节.通过以上实验规律的研究,便于常规工艺的调试和高方块电阻工艺中高方块电阻的制备和极差的优化.%As the key process of the production of crystalline silicon solar cell, the effect of diffusion or the square resistance's uniformity plays a very important role. The factors affecting the uniformity of the square resistance mainly include the flow rate of high N2, low N2 and O2 , the change of source saturation time and built in time, and the change of central temperature of the furnace. By changing these factors, a law which can effectively control the value of the square resistance and optimize the uniformity of the square resistance can be got. Both high N2 and low N2 can affect the uniformity of the square resistance, while temperature can affect the square resistance a lot.

  12. Research on Crystalline Silicon Solar Cells with Low Cost and High Efficiency%低成本、高效率晶硅太阳电池的研究

    Institute of Scientific and Technical Information of China (English)

    孟彦龙; 贾锐

    2011-01-01

    晶硅太阳电池的发展仍然以降低成本、提高效率为主题,围绕这一主题发展出来各种电池结构.文章概述了目前几种转化效率超过20%并且可实现低成本的电池结构,这些电池包括异质结本征薄层(HIT)电池、叉指状背接触(IBC)电池、金属绕通(MWT)电池及发射区绕通(EWT)电池.通过对这几种电池结构的利弊进行分析讨论,总结了各类电池制备所面临问题以及可能的解决方案,为今后低成本、高效率太阳电池的研究提供一些有益的借鉴.%Reducing cost and enhancing efficiency are main issues for the research of crystalline silicon solar cells. Up to now, many structures have been developed for the purpose of realizing cost-effective crystalline silicon solar cells. Several solar cells whose conversion efficiency can be higher than 20%, including heterojunction with intrinsic layer(HIT) cell,interdigitated back-contact(IBC) cell, metal-wrap-through(MWT) cell and emitter-wrap-through (EWT) cell, are reviewed in this paper. The characteristics of these cells are elaborated. The challenges to realize high rate of costs as well as the techniques referred are also reviewed. The discussions will give some direction for the future research on industrial crystalline silicon solar cells.

  13. A broadband-sensitive upconverter La(Ga{sub 0.5}Sc{sub 0.5})O{sub 3}:Er,Ni,Nb for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Yasuhiko, E-mail: takeda@mosk.tytlabs.co.jp; Mizuno, Shintaro; Luitel, Hom Nath; Tani, Toshihiko [Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2016-01-25

    We have developed an upconverter that significantly broadens the sensitive range, to overcome the shortcoming that conventional Er{sup 3+}-doped upconverters used for crystalline silicon solar cells can utilize only a small portion of the solar spectrum at around 1.55 μm. We have designed the combination of the sensitizers and host material to utilize photons not absorbed by silicon or Er{sup 3+} ions. Ni{sup 2+} ions have been selected as the sensitizers that absorb photons in the wavelength range between the silicon absorption edge (1.1 μm) and the Er{sup 3+} absorption band and transfer the energies to the Er{sup 3+} emitters, with La(Ga,Sc)O{sub 3} as the host material. The Ga to Sc ratio has been optimized to tune the location of the Ni{sup 2+} absorption band for sufficient energy transfer. Co-doping with Nb{sup 5+} ions is needed for charge balance to introduce divalent Ni{sup 2+} ions into the trivalent Ga{sup 3+} and Sc{sup 3+} sites. In addition to 1.45–1.58 μm photons directly absorbed by the Er{sup 3+} ions, we have demonstrated upconversion of 1.1–1.35 μm photons in the Ni{sup 2+} absorption band to 0.98 μm photons, using 10% Er, 0.5% Ni, and 0.5% Nb-doped La(Ga{sub 0.5}Sc{sub 0.5})O{sub 3}. The broadband-sensitive upconverter developed here can improve conversion efficiency of crystalline silicon solar cells more notably than conventional ones.

  14. Silicon: electrochemistry and luminescence

    NARCIS (Netherlands)

    Kooij, Ernst Stefan

    1997-01-01

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

  15. Silicon: electrochemistry and luminescence

    NARCIS (Netherlands)

    Kooij, Ernst Stefan

    1997-01-01

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

  16. Silicon: electrochemistry and luminescence

    NARCIS (Netherlands)

    Kooij, Ernst Stefan

    2001-01-01

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

  17. ‘Reliability of new poly (lactic-co-glycolic acid) membranes treated with oxygen plasma plus silicon dioxide layers for pre-prosthetic guided bone regeneration processes’

    Science.gov (United States)

    Castillo-Dalí, Gabriel; Batista-Cruzado, Antonio; López-Santos, Carmen; Rodríguez-González-Elipe, Agustín; Saffar, Jean-Louis; Lynch, Christopher D.; Gutiérrez-Pérez, José-Luis; Torres-Lagares, Daniel

    2017-01-01

    Background The use of cold plasmas may improve the surface roughness of poly(lactic-co-glycolic) acid (PLGA) membranes, which may stimulate the adhesion of osteogenic mediators and cells, thus accelerating the biodegradation of the barriers. Moreover, the incorporation of metallic-oxide particles to the surface of these membranes may enhance their osteoinductive capacity. Therefore, the aim of this paper was to evaluate the reliability of a new PLGA membrane after being treated with oxygen plasma (PO2) plus silicon dioxide (SiO2) layers for guided bone regeneration (GBR) processes. Material and Methods Circumferential bone defects (diameter: 11 mm; depth: 3 mm) were created on the top of eight experimentation rabbits’ skulls and were randomly covered with: (1) PLGA membranes (control), or (2) PLGA/PO2/SiO2 barriers. The animals were euthanized two months afterwards. A micromorphologic study was then performed using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone, concentration of osteoclasts, and intensity of ostheosynthetic activity were assessed and compared with those of the original bone tissue. The Kruskal-Wallis test was applied for between-group com Asignificance level of a=0.05 was considered. Results The PLGA/PO2/SiO2 membranes achieved the significantly highest new bone formation, length of mineralised bone, concentration of osteoclasts, and ostheosynthetic activity. The percentage of regenerated bone supplied by the new membranes was similar to that of the original bone tissue. Unlike what happened in the control group, PLGA/PO2/SiO2 membranes predominantly showed bone layers in advanced stages of formation. Conclusions The addition of SiO2 layers to PLGA membranes pre-treated with PO2 improves their bone-regeneration potential. Although further research is necessary to corroborate these conclusions in humans, this could be a promising strategy to rebuild the bone architecture prior to rehabilitate

  18. Optimization of conditions for growth of vanadium dioxide thin films on silicon by pulsed-laser deposition

    Directory of Open Access Journals (Sweden)

    Keisuke Shibuya

    2015-10-01

    Full Text Available We systematically examined the effects of the substrate temperature (TS and the oxygen pressure (PO2 on the structural and optical properties polycrystalline V O2 films grown directly on Si(100 substrates by pulsed-laser deposition. A rutile-type V O2 phase was formed at a TS ≥ 450 °C at PO2 values ranging from 5 to 20 mTorr, whereas other structures of vanadium oxides were stabilized at lower temperatures or higher oxygen pressures. The surface roughness of the V O2 films significantly increased at growth temperatures of 550 °C or more due to agglomeration of V O2 on the surface of the silicon substrate. An apparent change in the refractive index across the metal–insulator transition (MIT temperature was observed in V O2 films grown at a TS of 450 °C or more. The difference in the refractive index at a wavelength of 1550 nm above and below the MIT temperature was influenced by both the TS and PO2, and was maximal for a V O2 film grown at 450 °C under 20 mTorr. Based on the results, we derived the PO2 versus 1/TS phase diagram for the films of vanadium oxides, which will provide a guide to optimizing the conditions for growth of V O2 films on silicon platforms.

  19. Silicon dioxide obtained by Polymeric Precursor Method; Obtencao de dioxido de silicio pelo Metodo dos Precursores Polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, C.T.; Granado, S.R.; Lopes, S.A.; Cavalheiro, A.A., E-mail: cinthia_quimica@hotmail.com [Universidade Estadual de Mato Grosso do Sul (CPTREN/UEMS), Navirai, MS (Brazil). Centro de Pesquisas Tecnologicas em Recursos Naturais

    2011-07-01

    The Polymeric Precursor Method is able for obtaining several oxide material types with high surface area even obtained in particle form. Several MO{sub 2} oxide types such as titanium, silicon and zirconium ones can be obtained by this methodology. In this work, the synthesis of silicon oxide was monitored by thermal analysis, XRD and surface area analysis in order to demonstrate the influence of the several synthesis and calcining parameters. Surface area values as higher as 370m2/g and increasing in the micropore volume nm were obtained when the material was synthesized by using ethylene glycol as polymerizing agent. XRD analysis showed that the material is amorphous when calcinated at 600°C in despite of the time of calcining, but the material morphology is strongly influenced by the polymeric resin composition. Using Glycerol as polymerizing agent, the pore size increase and the surface area goes down with the increasing in decomposition time, when compared to ethylene glycol. (author)

  20. Amorphous silicon oxide layers for surface passivation and contacting of heterostructure solar cells of amorphous and crystalline silicon; Amorphe Siliziumoxidschichten zur Oberflaechenpassivierung und Kontaktierung von Heterostruktur-Solarzellen aus amorphen und kristallinem Silizium

    Energy Technology Data Exchange (ETDEWEB)

    Einsele, Florian

    2010-02-05

    Atomic hydrogen plays a dominant role in the passivation of crystalline silicon surfaces by layers of amorphous silicon. In order to research into this role, this thesis presents the method of hydrogen effusion from thin amorphous films of silicon (a-Si:H) and silicon oxide (a-SiO{sub x}:H). The oxygen concentration of the sub-stoichiometric a-SiO{sub x}:H films ranges up to 10 at.-%. The effusion experiment yields information about the content and thermal stability of hydrogen and about the microstructure of the films. A mathematical description of the diffusion process of atomic hydrogen yields an analytical expression of the effusion rate R{sub E} depending on the linearly increasing temperature in the experiment. Fitting of the calculated effusion rates R{sub E} to measured effusion spectra yields the diffusion coefficient of atomic hydrogen in a-SiO{sub x}:H. With increasing oxygen concentration, the diffusion coefficient of hydrogen in the a-SiO{sub x}:H films decreases. This is attributed to an increasing Si-H bond energy due to back bonded oxygen, resulting in a higher stability of hydrogen in the films. This result is confirmed by an increasing thermal stability of the p-type c-Si passivation with a-SiO{sub x}:H of increasing oxygen concentrations up to 5 at.-%. The passivation reaches very low recombination velocities of S < 10 cm/s at the interface. However, for higher oxygen concentrations up to 10 at.-%, the passivation quality decreases significantly. Here, infrared spectroscopy of Si-H vibrational modes and hydrogen effusion show an increase of hydrogen-rich interconnected voids in the films. This microstructure results in a high amount of molecular hydrogen (H{sub 2}) in the layers, which is not suitable for the saturation of c-Si interface defects. Annealing of the films at temperatures around 400 C leads to a release of H{sub 2} from the voids, as a result of which Si-Si bonds in the material reconstruct. Subsequently, hydrogen migration in the