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Crystalline Silicon (crystalline + silicon)

Distribution by Scientific Domains
Physics and Astronomy60%

Terms modified by Crystalline Silicon

  • crystalline silicon solar cell
    		•

    Selected Abstracts

    Heat treatment induced structural and optical properties of rf magnetron sputtered tantalum oxide films

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2007
    S. V. Jagadeesh Chandra
    Abstract Rf magnetron sputtering technique was employed for preparation of tantalum oxide films on quartz and crystalline silicon (111) substrates held at room temperature by sputtering of tantalum in an oxygen partial pressure of 1x10 -4 mbar. The films were annealed in air for an hour in the temperature range 573 , 993 K. The effect of annealing on the chemical binding configuration, structure and optical absorption of tantalum oxide films was systematically studied. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    From monosilane to crystalline silicon, part II: Kinetic considerations on thermal decomposition of pressurized monosilane

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2006
    J. O. Odden
    Kinetic aspects of the thermal decomposition of monosilane at 690,830 K and initial pressures of 0.1,3.7 MPa in a free-space reactor are considered. Neglecting the preparatory initiation period for the reaction (which is difficult to evaluate under the present dynamic conditions), the onset temperature for the decomposition is stipulated to some 700,710 K, independent of the initial monosilane pressure. The overall reaction appears to be of first order throughout the progressing decomposition process. We observe considerably lower reaction rates under the high-pressure conditions than existing models in the literature suggest. A modified model is proposed that simulates the observed reaction rates within ±1% and moreover predicts credible concentrations of the involved gaseous species. A key feature of the modified model is incorporation of two third-body assisted surface reactions, which generate monosilane from disilane and disilane from trisilane. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 309,321, 2006 [source]

    X-ray excited optical luminescence from crystalline silicon

    PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 9 2009
    Paul Gundel
    Abstract Synchrotron based X-ray excited optical luminescence (XEOL) has been measured with many direct bandgap semiconductors. We present XEOL measurements on crystalline silicon (Si), obtained despite of its indirect bandgap and the consequently low luminescence efficiency. Spectra of monocrystalline and multicrystalline (mc) Si at room temperature are compared to theoretical spectra. A possible application in the synchrotron-based research on mc-Si is exemplified by combining XEOL, X-ray fluorescence (XRF) spectroscopy, photoluminescence (PL) spectroscopy, and microscope images of grain boundaries. This approach can be utilized to investigate the recombination activity of metal precipitates, to analyze areas of different lifetimes on mc-Si samples and to correlate additional material parameters to XRF measurements. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Electrochemical stabilization of crystalline silicon with aromatic self-assembled monolayers in aqueous electrolytes

    PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2005
    Murat Tutus
    Abstract We report stable chemical engineering of hydrogen-terminated Si[111] surfaces in aqueous electrolytes by electrochemical grafting of aromatic monolayers. The topography and free energy of the engineered surface obtained from AFM and contact angle measurements confirmed homogeneous coating of the surface with a monolayer. Grafting of monolayers actually resulted in a clear suppression of the surface defect densities, demonstrated by photoluminescence lifetime. Changes in the surface chemical identities after grafting and post-treatments were followed by X-ray photoelectron spectroscopy (XPS). The electrochemical stability in aqueous electrolytes was assessed by impedance spectroscopy, revealing an improved stabilization of the Si/electrolyte interface by the grafted monomolecular film. This protocol was further applied for another aromatic compound, where the impact of 4-substituent functions could clearly be detected by photovoltage measurements. The chemical and electrochemical stability achieved here is promising for the successive deposition of biocompatible polymer films and lipid membranes. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Ab-initio modeling of a-Si and a-Si:H

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2010
    Ricardo M. Ribeiro
    Abstract The simulation of a-Si is complicated because there is no direct experimental data, as there are for crystals. Our approach to simulate a-Si is to build several relatively small amorphous samples and, later, the properties we wish to calculate are averaged over all samples. We applied the Wooten, Winer and Weaire bond switch to 64 atom cubic supercell of crystalline silicon. This mechanism was used to create 15 samples of continuous random network of silicon. For each supercell, the volume and atomic relaxation were allowed in order to minimize the total energy, using a density functional-pseudopotential code. The radial and angular distributions, the electronic and vibrational density of states, and the Raman spectra were calculated. The radial distribution agrees very well with experimental data. The angular distribution has its maximum at 109.4 degree. The experimental positions and relative intensities of the Transverse Optical (TO) and Transverse Acoustic vibrational modes are well reproduced, with 14 and 25 cm -1 peak deviations, respectively. The shape of the calculated Raman spectra agrees well with experimental data, being the intense TO peak shifted by 50 cm -1. The TO width at half-weight is very well reproduced. Introducing hydrogen in the a-Si samples, decorating all the undercoordinated Si atoms and at bond centres of floating bonds, the hydrogen vibrational frequencies of the relaxed structures agree very well with experimental data. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Structure, chemistry and electrical properties of extended defects in crystalline silicon for photovoltaics

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2009
    M. Seibt
    Abstract The electronic properties of present-day multicrystalline silicon (mc-Si) materials for photovoltaic applications are strongly influenced by point defects, their mutual interaction and their interaction with dislocations and grain boundaries. This paper presents results from fundamental investigations of metal impurity interaction with extended defects, namely a small-angle grain boundary and bulk microdefects. It is shown that the distribution of copper silicide precipitates closely follows the density of bulk microdefects indicating the underlying physics of ,good' and ,bad' grains frequently observed in mc-Si. Co-precipitation of copper and nickel in the same samples leads to virtually the same distribution of multimetal silicide precipitates which according to light-beam induced current measurements show the same recombination activity as single-metal silicide particles. Transmission electron microscopy is used to show that for copper-rich and nickel-rich conditions two types of silicides co-exist, i.e. Cu3Si precipitates containing a small amount of nickel and NiSi2 precipitates containing some copper. Finally, phosphorus-diffusion gettering (PDG) is discussed as the main gettering process used in presentday silicon photovoltaics. Special emphasis is put on the effect of extended defects and their interaction with metal impurities on PDG kinetics. It is shown that different limiting processes will be simultaneously operative in mc-Si as a result of inhomogeneous bulk defect distributions (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Very low surface recombination velocity of crystalline silicon passivated by phosphorus-doped a-SicxNy:H(n) alloys

    PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 2 2008
    R. Ferre
    Abstract Hydrogenated and phosphorus-doped amorphous silicon carbonitride films (a-SiCxNy:H(n)) were deposited by plasma-enhanced chemical vapor deposition (PECVD) on crystalline silicon surface in order to explore surface passivation properties. Very silicon-rich films yielded effective surface recombination velocities at 1 sun-illumination as low as 3,cm,s,1 and 2,cm,s,1 on 1,,,cm p- and n-type crystalline silicon substrates, respectively. In order to use them as anti-reflection coating, we increased alternatively either the carbon or nitrogen content of these films. Also, a combination of passivation and antireflective films was analyzed. Finally, we explored the passivation stability under high-temperature steps. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Comparison of potential solar electricity output from fixed-inclined and two-axis tracking photovoltaic modules in Europe

    PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2008
    Thomas Huld
    Abstract We present an approach to determine the potential energy gains of flat plate non-concentrating photovoltaic systems for the case of two-axis tracking and two inclination angles with fixed orientation (assuming biannual adjustment) compared to the configuration of single fixed optimum angle. The calculation is based on the Photovoltaic Geographic Information System (PVGIS), which integrates modelling tools with the pan-European solar radiation database. The results indicate that in the case of a PV system with two seasonal inclination angles, the maximum yearly gains, compared to the single fixed optimum angle, do not exceed 60,70,kWh per kWp in the Mediterranean region, while in the Baltic and North Sea regions this configuration gives less than 20,kWh extra. For the case of two-axis tracking, the relative energy gain compared to single fixed optimum angle is highest in the Northern latitudes but the absolute gain is much higher in the South. Typical yearly gains in Portugal and the Mediterranean region are in the range of 400,600,kWh per kWp. The smallest absolute increase is found in the Northwest and Central Europe including the British Isles, where it is lower than 250,kWh per kWp. For crystalline silicon we also investigate the effects of temperature and shallow-angle reflectivity on the comparison between fixed and tracking systems. While both effects reduce the overall energy output, the temperature degradation is stronger for tracking systems while the reflectivity reduces output more for fixed systems. The combined effect is almost equal for fixed and two-axis tracking systems. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Limiting efficiency of crystalline silicon solar cells due to Coulomb-enhanced Auger recombination

    PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 2 2003
    Mark J. Kerr
    Excitonic effects are known to enhance the rate of intrinsic recombination processes in crystalline silicon. New calculations for the limiting efficiency of silicon solar cells are presented here, based on a recent parameterization for the Coulomb-enhanced Auger recombination rate, which accounts for its dopant type and dopant density dependence at an arbitrary injection level. Radiative recombination has been included along with photon recycling effects modeled by three-dimensional ray tracing. A maximum cell efficiency of 29.05% has been calculated for a 90-,m-thick cell made from high resistivity silicon at 25°C. For 1,,,cm p -type silicon, the maximum efficiency reduces from 28.6% for a 55-,m-thick cell in the absence of surface recombination, down to 27.0% for a thickness in the range 300,500,,m when surface recombination limits the open-circuit voltage to 720,mV. Copyright © 2002 John Wiley & Sons, Ltd. [source]