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Sample records for single crystalline silicon

  1. Single crystalline mesoporous silicon nanowires

    SciTech Connect

    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.

  2. Single crystalline mesoporous silicon nanowires

    SciTech Connect

    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.

  3. Subsurface damage of single crystalline silicon carbide in nanoindentation tests.

    PubMed

    Yan, Jiwang; Gai, Xiaohui; Harada, Hirofumi

    2010-11-01

    The response of single crystalline silicon carbide (SiC) to a Berkovich nanoindenter was investigated by examining the indents using a transmission electron microscope and the selected area electron diffraction technique. It was found that the depth of indentation-induced subsurface damage was far larger than the indentation depth, and the damaging mechanism of SiC was distinctly different from that of single crystalline silicon. For silicon, a broad amorphous region is formed underneath the indenter after unloading; for SiC, however, no amorphous phase was detected. Instead, a polycrystalline structure with a grain size of ten nanometer level was identified directly under the indenter tip. Micro cracks, basal plane dislocations and possible cross slips were also found around the indent. These finding provide useful information for ultraprecision manufacturing of SiC wafers. PMID:21138038

  4. Dynamic crack propagation in single-crystalline silicon

    SciTech Connect

    Cramer, T.; Gumbsch, P.; Wanner, A.

    1999-08-01

    Tensile tests on notched plates of single-crystalline silicon were carried out at high overloads. Cracks were forced to propagate on {l_brace}110{r_brace} planes in a {l_angle}1{bar 1}0{r_angle} direction. The dynamics of the fracture process was measured using the potential drop technique and correlated with the fracture surface morphology. Crack propagation velocity did not exceed a terminal velocity of v{sub c} = 3,800 m/s, which corresponds to 83% of the Rayleigh wave velocity v{sub R}. Specimens fractured at low stresses exhibited crystallographic cleavage whereas a transition from mirror-like smooth regions to rougher hackle zones was observed in case of the specimens fractured at high stresses. Inspection of the mirror zone at high magnification revealed a deviation of the {l_brace}110{r_brace} plane onto {l_brace}111{r_brace}crystallographic facets.

  5. Laser ablation of single-crystalline silicon by radiation of pulsed frequency-selective fiber laser

    NASA Astrophysics Data System (ADS)

    Veiko, V. P.; Skvortsov, A. M.; Huynh, C. T.; Petrov, A. A.

    2015-07-01

    We have studied the process of destruction of the surface of a single-crystalline silicon wafer scanned by the beam of a pulsed ytterbium-doped fiber laser radiation with a wavelength of λ = 1062 nm. It is established that the laser ablation can proceed without melting of silicon and the formation of a plasma plume. Under certain parameters of the process (radiation power, beam scan velocity, and beam overlap density), pronounced oxidation of silicon microparticles with the formation of a characteristic loose layer of fine powdered silicon dioxide has been observed for the first time. The range of lasing and beam scanning regimes in which the growth of SiO2 layer takes place is determined.

  6. Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application.

    PubMed

    Reshak, A H; Shahimin, M M; Shaari, S; Johan, N

    2013-11-01

    The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells. PMID:24139943

  7. Graphene Enhances Li Storage Capacity of Porous Single-crystalline Silicon Nanowires

    SciTech Connect

    Wang, X.; Han, W.

    2010-12-01

    We demonstrated that graphene significantly enhances the reversible capacity of porous silicon nanowires used as the anode in Li-ion batteries. We prepared our experimental nanomaterials, viz., graphene and porous single-crystalline silicon nanowires, respectively, using a liquid-phase graphite exfoliation method and an electroless HF/AgNO{sub 3} etching process. The Si porous nanowire/graphene electrode realized a charge capacity of 2470 mAh g{sup -1} that is much higher than the 1256 mAh g{sup -1} of porous Si nanowire/C-black electrode and 6.6 times the theoretical capacity of commercial graphite. This relatively high capacity could originate from the favorable charge-transportation characteristics of the combination of graphene with the porous Si 1D nanostructure.

  8. Oxygen recoil implant from SiO{sub 2} layers into single-crystalline silicon

    SciTech Connect

    Wang, G.; Chen, Y.; Li, D.; Oak, S.; Srivastav, G.; Banerjee, S.; Tasch, A.; Merrill, P.; Bleiler, R.

    2001-06-01

    It is important to understand the distribution of recoil-implanted atoms and the impact on device performance when ion implantation is performed at a high dose through surface materials into single crystalline silicon. For example, in ultralarge scale integration impurity ions are often implanted through a thin layer of screen oxide and some of the oxygen atoms are inevitably recoil implanted into single-crystalline silicon. Theoretical and experimental studies have been performed to investigate this phenomenon. We have modified the Monte Carlo ion implant simulator, UT-Marlowe (B. Obradovic, G. Wang, Y. Chen, D. Li, C. Snell, and A. F. Tasch, UT-MARLOWE Manual, 1999), which is based on the binary collision approximation, to follow the full cascade and to dynamically modify the stoichiometry of the Si layer as oxygen atoms are knocked into it. CPU reduction techniques are used to relieve the demand on computational power when such a full cascade simulation is involved. Secondary ion mass spectrometry (SIMS) profiles of oxygen have been carefully obtained for high dose As and BF{sub 2} implants at different energies through oxide layers of various thicknesses, and the simulated oxygen profiles are found to agree very well with the SIMS data. {copyright} 2001 American Institute of Physics.

  9. Dependence of Fracture Toughness on Crystallographic Orientation in Single-Crystalline Cubic (β) Silicon Carbide

    SciTech Connect

    Pharr, M.; Katoh, Y.; Bei, H.

    2006-01-01

    Along with other desirable properties, the ability of silicon carbide (SiC) to retain high strength after elevated temperature exposures to neutron irradiation renders it potentially applicable in fusion and advanced fission reactors. However, properties of the material such as room temperature fracture toughness must be thoroughly characterized prior to such practical applications. The objective of this work is to investigate the dependence of fracture toughness on crystallographic orientation for single-crystalline β-SiC. X-ray diffraction was first performed on the samples to determine the orientation of the crystal. Nanoindentation was used to determine a hardness of 39.1 and 35.2 GPa and elastic modulus of 474 and 446 GPa for the single-crystalline and polycrystalline samples, respectively. Additionally, crack lengths and indentation diagonals were measured via a Vickers micro-hardness indenter under a load of 100 gf for different crystallographic orientations with indentation diagonals aligned along fundamental cleavage planes. Upon examination of propagation direction of cracks, the cracks usually did not initiate and propagate from the corners of the indentation where the stresses are concentrated but instead from the indentation sides. Such cracks clearly moved along the {1 1 0} family of planes (previously determined to be preferred cleavage plane), demonstrating that the fracture toughness of SiC is comparatively so much lower along this set of planes that the lower energy required to cleave along this plane overpowers the stress-concentration at indentation corners. Additionally, fracture toughness in the <1 1 0> direction was 1.84 MPa·m1/2, lower than the 3.46 MPa·m1/2 measured for polycrystalline SiC (which can serve as an average of a spectrum of orientations), further demonstrating that single-crystalline β-SiC has a strong fracture toughness anisotropy.

  10. Fabrication of 3D fractal structures using nanoscale anisotropic etching of single crystalline silicon

    NASA Astrophysics Data System (ADS)

    Berenschot, Erwin J. W.; Jansen, Henri V.; Tas, Niels R.

    2013-05-01

    When it comes to high-performance filtration, separation, sunlight collection, surface charge storage or catalysis, the effective surface area is what counts. Highly regular fractal structures seem to be the perfect candidates, but manufacturing can be quite cumbersome. Here it is shown--for the first time—that complex 3D fractals can be engineered using a recursive operation in conventional micromachining of single crystalline silicon. The procedure uses the built-in capability of the crystal lattice to form self-similar octahedral structures with minimal interference of the constructor. The silicon fractal can be used directly or as a mold to transfer the shape into another material. Moreover, they can be dense, porous, or like a wireframe. We demonstrate, after four levels of processing, that the initial number of octahedral structures is increased by a factor of 625. Meanwhile the size decreases 16 times down to 300 nm. At any level, pores of less than 100 nm can be fabricated at the octahedral vertices of the fractal. The presented technique supports the design of fractals with Hausdorff dimension D free of choice and up to D = 2.322.

  11. Optical phased array using single crystalline silicon high-contrast-gratings for beamsteering

    NASA Astrophysics Data System (ADS)

    Yoo, Byung-Wook; Chan, Trevor; Megens, Mischa; Sun, Tianbo; Yang, Weijian; Rao, Yi; Horsley, David A.; Chang-Hasnain, Connie J.; Wu, Ming C.

    2013-03-01

    We present a single crystalline silicon optical phased array using high-contrast-gratings (HCG) for fast two dimensional beamforming and beamsteering at 0.5 MHz. Since there are various applications for beamforming and beamsteering such as 3D imaging, optical communications, and light detection and ranging (LIDAR), it is great interest to develop ultrafast optical phased arrays. However, the beamsteering speed of optical phased arrays using liquid crystal and electro-wetting are typically limited to tens of milliseconds. Optical phased arrays using micro-electro-mechanical systems (MEMS) technologies can operate in the submegahertz range, but generally require metal coatings. The metal coating unfortunately cause bending of mirrors due to thermally induced stress. The novel MEMS-based optical phased array presented here consists of electrostatically driven 8 × 8 HCG pixels fabricated on a silicon-on-insulator (SOI) wafer. The HCG mirror is designed to have 99.9% reflectivity at 1550 nm wavelength without any reflective coating. The size of the HCG mirror is 20 × 20 μm2 and the mass is only 140 pg, much lighter than traditional MEMS mirrors. Our 8 × 8 optical phased array has a total field of view of +/-10° × 10° and a beam width of 2°. The maximum phase shift regarding the actuation gap defined by a 2 μm buried oxide layer of a SOI wafer is 1.7π at 20 V.

  12. Generation of single-crystalline domain in nano-scale silicon pillars by near-field short pulsed laser

    NASA Astrophysics Data System (ADS)

    In, Jung Bin; Xiang, Bin; Hwang, David J.; Ryu, Sang-Gil; Kim, Eunpa; Yoo, Jae-Hyuck; Dubon, Oscar; Minor, Andrew M.; Grigoropoulos, Costas P.

    2014-01-01

    We observe laser-induced grain morphology change in silicon nanopillars under a transmission electron microscopy (TEM) environment. We couple the TEM with a near-field scanning optical microscopy pulsed laser processing system. This novel combination enables immediate scrutiny on the grain morphologies that the pulsed laser irradiation produces. We find unusual transformation of the tip of the amorphous or polycrystalline silicon pillar into a single crystalline domain via melt-mediated crystallization. On the basis of the three-dimensional finite difference simulation result and the dark field TEM data, we propose that the creation of the distinct single crystalline tip originates from the dominant grain growth initiated at the apex of the non-planar liquid-solid interface. Our microscopic observation provides a fundamental basis for laser-induced conversion of amorphous nanostructures into coarse-grained crystals.

  13. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    NASA Astrophysics Data System (ADS)

    Christiansen, S. H.; Chou, J. W.; Becker, M.; Sivakov, V.; Ehrhold, K.; Berger, A.; Chou, W. C.; Chuu, D. S.; Gösele, U.

    2009-04-01

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  14. Graphene-silicon layered structures on single-crystalline Ir(111) thin films

    SciTech Connect

    Que, Yande D.; Tao, Jing; Zhang, Yong; Wang, Yeliang L.; Wu, Lijun J.; Zhu, Yimei M.; Kim, Kisslinger; Weinl, Michael; Schreck, Matthias; Shen, Chengmin M.; Du, Shixuan X.; Liu, Yunqi Q.; Gao, H. -J.; Huang, Li; Xu, Wenyan Y.

    2015-01-20

    Epitaxial growth of graphene on transition metal crystals, such as Ru,⁽¹⁻³⁾ Ir,⁽⁴⁻⁶⁾ and Ni,⁽⁷⁾ provides large-area, uniform graphene layers with controllable defect density, which is crucial for practical applications in future devices. To decrease the high cost of single-crystalline metal bulks, single-crystalline metal films are strongly suggested as the substrates for epitaxial growth large-scale high-quality graphene.⁽⁸⁻¹⁰⁾ Moreover, in order to weaken the interactions of graphene with its metal host, which may result in a suppression of the intrinsic properties of graphene,⁽¹¹ ¹²⁾ the method of element intercalation of semiconductors at the interface between an epitaxial graphene layer and a transition metal substrate has been successfully realized.⁽¹³⁻¹⁶⁾

  15. Graphene-silicon layered structures on single-crystalline Ir(111) thin films

    DOE PAGESBeta

    Que, Yande D.; Tao, Jing; Zhang, Yong; Wang, Yeliang L.; Wu, Lijun J.; Zhu, Yimei M.; Kim, Kisslinger; Weinl, Michael; Schreck, Matthias; Shen, Chengmin M.; et al

    2015-01-20

    Epitaxial growth of graphene on transition metal crystals, such as Ru,⁽¹⁻³⁾ Ir,⁽⁴⁻⁶⁾ and Ni,⁽⁷⁾ provides large-area, uniform graphene layers with controllable defect density, which is crucial for practical applications in future devices. To decrease the high cost of single-crystalline metal bulks, single-crystalline metal films are strongly suggested as the substrates for epitaxial growth large-scale high-quality graphene.⁽⁸⁻¹⁰⁾ Moreover, in order to weaken the interactions of graphene with its metal host, which may result in a suppression of the intrinsic properties of graphene,⁽¹¹ ¹²⁾ the method of element intercalation of semiconductors at the interface between an epitaxial graphene layer and a transitionmore » metal substrate has been successfully realized.⁽¹³⁻¹⁶⁾« less

  16. Crystalline Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Green, Martin A.

    2015-10-01

    The following sections are included: * Overview * Silicon cell development * Substrate production * Cell processing * Cell costs * Opportunities for improvement * Silicon-supported thin films * Summary * Acknowledgement * References

  17. Structural defects in crystalline silicon

    NASA Technical Reports Server (NTRS)

    Sirtl, E.

    1985-01-01

    The basic photovoltaic properties of a given crystalline silicon specimen seem to be governed by density and nature of two to three dimensional lattice defects. These are mainly generated by primary growth conditions as grain boundaries of more or less intrinsic character or second phase precipitates from supersaturated solutions of carbon or oxygen. Considerably high values of both solubility and diffusivity in connection with their abundance in common refractory material systems account for the predominance of the two particular elements. Unsaturated dislocations of different types very often can be seen as a consequence of the existence of more dimensional defects as described initially. The final performance of a solar cell is dependent of the concentration and distribution of recombination active centers in the different regions of this device. Typical representatives are fast diffusing transition metals in form of either single atoms or simple complexes. Their avoidance, annihilation, or removal is of great concern in different fields of electronic materials development.

  18. Direct writing of continuous and discontinuous sub-wavelength periodic surface structures on single-crystalline silicon using femtosecond laser

    SciTech Connect

    Kuladeep, Rajamudili; Sahoo, Chakradhar; Narayana Rao, Desai E-mail: dnr-laserlab@yahoo.com

    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.

  19. Shape- and dimension-controlled single-crystalline silicon and SiGe nanotubes: toward nanofluidic FET devices.

    PubMed

    Ben Ishai, Moshit; Patolsky, Fernando

    2009-03-18

    We report here on the formation of robust and entirely hollow single-crystalline silicon nanotubes, from various tubular to conical structures, with uniform and well-controlled inner diameter, ranging from as small as 1.5 up to 500 nm, and controllable wall thickness. Second, and most important, these nanotubes can be doped in situ with different concentrations of boron and phosphine to give p/n-type semiconductor nanotubes. Si(x)Ge(1-x)-alloy nanotubes can also be prepared. This synthetic approach enables independent and precise control of diameter, wall thickness, shape, taper angle, crystallinity, and chemical/electrical characteristics of the nanotubular structures obtained. Notably, diameter and wall thickness of nearly any size can be obtained. This unique advantage allows the achievement of novel and perfectly controlled high-quality electronic materials and the tailoring of the tube properties to better fit many biological, chemical, and electrical applications. Electrical devices based on this new family of electrically active nanotubular building-block structures are also described with a view toward the future realization of nanofluidic FET devices. PMID:19226180

  20. Method of making selective crystalline silicon regions containing entrapped hydrogen by laser treatment

    DOEpatents

    Pankove, Jacques I.; Wu, Chung P.

    1982-01-01

    A novel hydrogen rich single crystalline silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystalline silicon without out-gasing the hydrogen. The new material can be used to fabricate semi-conductor devices such as single crystalline silicon solar cells with surface window regions having a greater band gap energy than that of single crystalline silicon without hydrogen.

  1. Interfacial Layer Control by Dry Cleaning Technology for Polycrystalline and Single Crystalline Silicon Growth.

    PubMed

    Im, Dong-Hyun; Kong-Soo Lee; Kang, Yoongoo; Jeong, Myoungho; Park, Kwang Wuk; Lee, Soon-Gun; Ma, Jin-Won; Kim, Youngseok; Kim, Bonghyun; Im, Ki-Vin; Lim, Hanjin; Lee, Jeong Yong

    2016-05-01

    Native oxide removal prior to poly-Si contact and epitaxial growth of Si is the most critical technology to ensure process and device performances of poly-Si plugs and selective epitaxial growth (SEG) layers for DRAM, flash memory, and logic device. Recently, dry cleaning process for interfacial oxide removal has attracted a world-wide attention due to its superior passivation properties to conventional wet cleaning processes. In this study, we investigated the surface states of Si substrate during and after dry cleaning process, and the role of atomic elements including fluorine and hydrogen on the properties of subsequent deposited silicon layer using SIMS, XPS, and TEM analysis. The controlling of residual fluorine on the Si surface after dry cleaning is a key factor for clean interface. The mechanism of native oxide re-growth caused by residual fluorine after dry cleaning is proposed based on analytical results. PMID:27483844

  2. Birefringence measurements on crystalline silicon

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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 polarization-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 {{Δ }} n≈ {10}-7 at a laser wavelength of 1550 nm 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.

  3. Strain Anisotropies and Self-limiting Capacities in Single-crystalline 3D Silicon Microstructures: Models for High Energy Denisty Lithium-Ion Battery Anodes

    SciTech Connect

    Goldman, Jason L.; Long, Brandon R.; Gewirth, Andrew A.; Nuzzo, Ralph G

    2011-01-01

    This study examines the crystallographic anisotropy of strain evolution in model, single-crystalline silicon anode microstructures on electrochemical intercalation of lithium atoms. The 3D hierarchically patterned single- crystalline silicon microstructures used as model anodes were prepared using combined methods of photolithography and anisotropic dry and wet chemical etching. Silicon anodes, which possesses theoretically ten times the energy density by weight compared to conventional carbon anodes, reveal highly anisotropic but more importantly, variably recoverable crystallographic strains during cycling. Model strain-limiting silicon anode architectures that mitigate these impacts are highlighted. By selecting a specific design for the silicon anode microstructure, and exploiting the crystallographic anisotropy of strain evolution upon lithium intercalation to control the direction of volumetric expansion, the volume available for expansion and thus the charging capacity of these structures can be broadly varied. We highlight exemplary design rules for this self-strain-limited charging in which an anode can be variably optimized between capacity and stability. Strain-limited capacities ranging from 677 mAhg-1 to 2833 mAhg-1 were achieved by constraining the area available for volumetric expansion via the design rules of the microstructures.

  4. Basic research challenges in crystalline silicon photovoltaics

    SciTech Connect

    Werner, J.H.

    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.

  5. Single crystalline magnetite nanotubes.

    PubMed

    Liu, Zuqin; Zhang, Daihua; Han, Song; Li, Chao; Lei, Bo; Lu, Weigang; Fang, Jiye; Zhou, Chongwu

    2005-01-12

    We descried a method to synthesize single crystalline Fe3O4 nanotubes by wet-etching the MgO inner cores of MgO/Fe3O4 core-shell nanowires. Homogeneous Fe3O4 nanotubes with controllable length, diameter, and wall thickness have been obtained. Resistivity of the Fe3O4 nanotubes was estimated to be approximately 4 x 10-2 Omega cm at room temperature. Magnetoresistance of approximately 1% was observed at T = 77 K when a magnetic field of B = 0.7 T was applied. The synthetic strategy presented here may be extended to a variety of materials such as YBCO, PZT, and LCMO which should provide ideal candidates for fundamental studies of superconductivity, piezoelectricity, and ferromagnetism in nanoscale structures. PMID:15631421

  6. Zero lattice mismatch and twin-free single crystalline ScN buffer layers for GaN growth on silicon

    NASA Astrophysics Data System (ADS)

    Lupina, L.; Zoellner, M. H.; Niermann, T.; Dietrich, B.; Capellini, G.; Thapa, S. B.; Haeberlen, M.; Lehmann, M.; Storck, P.; Schroeder, T.

    2015-11-01

    We report the growth of thin ScN layers deposited by plasma-assisted molecular beam epitaxy on Sc2O3/Y2O3/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/Sc2O3/Y2O3 buffer system a very promising template for the growth of high quality GaN layers on silicon.

  7. Zero lattice mismatch and twin-free single crystalline ScN buffer layers for GaN growth on silicon

    SciTech Connect

    Lupina, L.; Zoellner, M. H.; Dietrich, B.; Capellini, G.; Niermann, T.; Lehmann, M.; Thapa, S. B.; Haeberlen, M.; Storck, P.; Schroeder, T.

    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.

  8. High efficiency crystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Sah, C. Tang

    1986-01-01

    A review of the entire research program since its inception ten years ago is given. The initial effort focused on the effects of impurities on the efficiency of silicon solar cells to provide figures of maximum allowable impurity density for efficiencies up to about 16 to 17%. Highly accurate experimental techniques were extended to characterize the recombination properties of the residual imputities in the silicon solar cell. A numerical simulator of the solar cell was also developed, using the Circuit Technique for Semiconductor Analysis. Recent effort focused on the delineation of the material and device parameters which limited the silicon efficiency to below 20% and on an investigation of cell designs to break the 20% barrier. Designs of the cell device structure and geometry can further reduce recombination losses as well as the sensitivity and criticalness of the fabrication technology required to exceed 20%. Further research is needed on the fundamental characterization of the carrier recombination properties at the chemical impurity and physical defect centers. It is shown that only single crystalline silicon cell technology can be successful in attaining efficiencies greater than 20%.

  9. High-efficiency crystalline silicon technology development

    NASA Technical Reports Server (NTRS)

    Prince, M. B.

    1984-01-01

    The rationale for pursuing high efficiency crystalline silicon technology research is discussed. Photovoltaic energy systems are reviewed as to their cost effectiveness and their competitiveness with other energy systems. The parameters of energy system life are listed and briefly reviewed.

  10. Porous silicon Bragg reflectors on multi-crystalline silicon wafer with p-n junction

    NASA Astrophysics Data System (ADS)

    Ivanov, I. I.; Skryshevsky, V. A.; Kyslovets, O. S.; Nychyporuk, T.; Lemiti, M.

    2016-04-01

    Bragg reflectors consisting of the sequence of dielectric layers are considered to create p-n junction solar cells (SC) with improved efficiency in the longwave spectral range. Bragg mirrors (BM) based on porous silicon (PS) mutilayers at the backside of single crystalline and multicrystalline silicon wafer were formed by electrochemically etching. Maximal experimental reflectivity for BM on multicrystalline substrate achieves 62% due to the natural crystallites disorientation of multicrystalline substrate, whereas for single crystalline silicon the reflectivity in maximum is 87%. BM was formed also on rear side of multicrystalline silicon wafer with p-n junction.

  11. Laser recrystallization for efficient multi-crystalline silicon solar cell

    NASA Astrophysics Data System (ADS)

    Song, Lihui; Wilson, John; Lee, James

    2016-08-01

    A multi-crystalline silicon wafer contains dislocations and grain boundaries, which are detrimental to the performance of the multi-crystalline silicon solar cell. The dislocations and grain boundaries extend across the junction and dramatically degrade the ideality and fill factor of the cell. In this paper, a laser is used to recrystallize the emitter region of a multi-crystalline silicon wafer to remove crystallographic defects present in the junction. It was demonstrated that, with an appropriate laser power and scan speed, laser recrystallized patterns can have an enhanced photoluminescence response and internal quantum efficiency. Backscattered electron image and x-ray diffraction analyses also revealed that the laser recrystallized layer resembles a single crystalline like layer. Introducing a full area laser recrystallized layer may improve the open circuit voltage and fill factor of the cell, which significantly improved cell efficiency. External quantum efficiency and dark I–V measurements consistently supported this result.

  12. Method of making selective crystalline silicon regions containing entrapped hydrogen by laser treatment

    DOEpatents

    Pankove, J.I.; Wu, C.P.

    1982-03-30

    A novel hydrogen rich single crystalline silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystalline silicon without out-gassing the hydrogen. The new material can be used to fabricate semi-conductor devices such as single crystalline silicon solar cells with surface window regions having a greater band gap energy than that of single crystalline silicon without hydrogen. 2 figs.

  13. University Crystalline Silicon Photovoltaics Research and Development

    SciTech Connect

    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.

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

    SciTech Connect

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

    2013-02-05

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

  15. Meniscus-force-mediated layer transfer technique using single-crystalline silicon films with midair cavity: Application to fabrication of CMOS transistors on plastic substrates

    NASA Astrophysics Data System (ADS)

    Sakaike, Kohei; Akazawa, Muneki; Nakagawa, Akitoshi; Higashi, Seiichiro

    2015-04-01

    A novel low-temperature technique for transferring a silicon-on-insulator (SOI) layer with a midair cavity (supported by narrow SiO2 columns) by meniscus force has been proposed, and a single-crystalline Si (c-Si) film with a midair cavity formed in dog-bone shape was successfully transferred to a poly(ethylene terephthalate) (PET) substrate at its heatproof temperature or lower. By applying this proposed transfer technique, high-performance c-Si-based complementary metal-oxide-semiconductor (CMOS) transistors were successfully fabricated on the PET substrate. The key processes are the thermal oxidation and subsequent hydrogen annealing of the SOI layer on the midair cavity. These processes ensure a good MOS interface, and the SiO2 layer works as a “blocking” layer that blocks contamination from PET. The fabricated n- and p-channel c-Si thin-film transistors (TFTs) on the PET substrate showed field-effect mobilities of 568 and 103 cm2 V-1 s-1, respectively.

  16. Oxygen, carbon, hydrogen and nitrogen in crystalline silicon

    SciTech Connect

    Mikkelsen, J.C.; Pearton, S.J.; Corbett, J.W.; Pennycook, S.J

    1986-01-01

    These proceedings collect papers on interstitial material in silicon. Topics include: hydrogen in crystalline silicon, low energy hydrogen ion bombarded silicon, oxygen in silicon, oxygen thermal donor formation, thermal donor generation and annihilation effects on oxygen precipitation oxygen effects on plastic flow during growth of dendrixic web silicon, nitrogen in silicon, off-center nitrogen and oxygen in silicon, and thermal donor hierarchies in silicon and germanium.

  17. Transistors using crystalline silicon devices on glass

    DOEpatents

    McCarthy, Anthony M.

    1995-01-01

    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.

  18. The microstructure matters: breaking down the barriers with single crystalline silicon as negative electrode in Li-ion batteries.

    PubMed

    Sternad, M; Forster, M; Wilkening, M

    2016-01-01

    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%). PMID:27531589

  19. Two- and three-dimensional folding of thin film single-crystalline silicon for photovoltaic power applications

    PubMed Central

    Guo, Xiaoying; Li, Huan; Yeop Ahn, Bok; Duoss, Eric B.; Hsia, K. Jimmy; Lewis, Jennifer A.; Nuzzo, Ralph G.

    2009-01-01

    Fabrication of 3D electronic structures in the micrometer-to-millimeter range is extremely challenging due to the inherently 2D nature of most conventional wafer-based fabrication methods. Self-assembly, and the related method of self-folding of planar patterned membranes, provide a promising means to solve this problem. Here, we investigate self-assembly processes driven by wetting interactions to shape the contour of a functional, nonplanar photovoltaic (PV) device. A mechanics model based on the theory of thin plates is developed to identify the critical conditions for self-folding of different 2D geometrical shapes. This strategy is demonstrated for specifically designed millimeter-scale silicon objects, which are self-assembled into spherical, and other 3D shapes and integrated into fully functional light-trapping PV devices. The resulting 3D devices offer a promising way to efficiently harvest solar energy in thin cells using concentrator microarrays that function without active light tracking systems. PMID:19934059

  20. The microstructure matters: breaking down the barriers with single crystalline silicon as negative electrode in Li-ion batteries

    PubMed Central

    Sternad, M.; Forster, M.; Wilkening, M.

    2016-01-01

    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%). PMID:27531589

  1. Research on crystalline silicon solar cells

    SciTech Connect

    Milstein, J.B.; Tsuo, Y.S.

    1984-06-01

    Since the 16th IEEE Photovoltaic Specialists Conference, the focus of the Crystalline Silicon Solar Cell Task at the Solar Energy Research Institute (SERI) has narrowed somewhat. Responsibility for silicon material preparation and ribbon growth were consolidated at the Jet Propulsion Laboratory (JPL) at the end of FY 1983. Five subcontracts were awarded under RFP No. RB-2-02090, Research on Basic Understanding of High Efficiency in Silicon Solar Cells. JPL and Oak Ridge National Laboratory are also working on high-efficiency solar cell research under SERI subcontract. Reports of past solar cell improvements have prompted appreciable interest in the physical, chemical, and electrical transport properties of grain boundaries and other electrically active defects. Studies to achieve better understanding of the hydrogen passivation process are being conducted at various subcontractors, and our in-house research continues. This paper presents the results of these efforts as well as future directions.

  2. A holistic view of crystalline silicon module reliability

    SciTech Connect

    Hanoka, J.I.

    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.

  3. Solar cell structure incorporating a novel single crystal silicon material

    DOEpatents

    Pankove, Jacques I.; Wu, Chung P.

    1983-01-01

    A novel hydrogen rich single crystal silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystal silicon without out-gassing the hydrogen. The new material can be used to fabricate semiconductor devices such as single crystal silicon solar cells with surface window regions having a greater band gap energy than that of single crystal silicon without hydrogen.

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

    SciTech Connect

    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.

  5. (Preoxidation cleaning optimization for crystalline silicon)

    SciTech Connect

    Not Available

    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.

  6. Effect of nitridation surface treatment on silicon (1 1 1) substrate for the growth of high quality single-crystalline GaN hetero-epitaxy layer by MOCVD

    NASA Astrophysics Data System (ADS)

    Rahman, Mohd Nazri Abd.; Yusuf, Yusnizam; Mansor, Mazwan; Shuhaimi, Ahmad

    2016-01-01

    A single-crystalline with high quality of gallium nitride epilayers was grown on silicon (1 1 1) substrate by metal organic chemical vapor deposition. The process of nitridation surface treatment was accomplished on silicon (1 1 1) substrate by flowing the ammonia gaseous. Then, it was followed by a thin aluminum nitride nucleation layer, aluminum nitride/gallium nitride multi-layer and a thick gallium nitride epilayer. The influence of in situ nitridation surface treatment on the crystallinity quality of gallium nitride epilayers was studied by varying the nitridation times at 40, 220 and 400 s, respectively. It was shown that the nitridation times greatly affect the structural properties of the grown top gallium nitride epilayer on silicon (1 1 1) substrate. In the (0 0 0 2) and (1 0 1 bar 2) X-ray rocking curve analysis, a narrower value of full width at half-maximum has been obtained as the nitridation time increased. This is signifying the reduction of dislocation density in the gallium nitride epilayer. This result was supported by the value of bowing and root mean square roughness measured by surface profilometer and atomic force microscopy. Furthermore, a crack-free gallium nitride surface with an abrupt cross-sectional structure that observed using field effect scanning electron microscopy was also been obtained. The phi-scan curve of asymmetric gallium nitride proved the top gallium nitride epilayer exhibited a single-crystalline structure.

  7. Transistors using crystalline silicon devices on glass

    DOEpatents

    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.

  8. Crystalline-silicon photovoltaics: Necessary and sufficient

    SciTech Connect

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

    1995-01-01

    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.

  9. Crystalline to amorphous transformation in silicon

    SciTech Connect

    Cheruvu, S.M.

    1982-09-01

    In the present investigation, an attempt was made to understand the fundamental mechanism of crystalline-to-amorphous transformation in arsenic implanted silicon using high resolution electron microscopy. A comparison of the gradual disappearance of simulated lattice fringes with increasing Frenkel pair concentration with the experimental observation of sharp interfaces between crystalline and amorphous regions was carried out leading to the conclusion that when the defect concentration reaches a critical value, the crystal does relax to an amorphous state. Optical diffraction experiments using atomic models also supported this hypothesis. Both crystalline and amorphous zones were found to co-exist with sharp interfaces at the atomic level. Growth of the amorphous fraction depends on the temperature, dose rate and the mass of the implanted ion. Preliminary results of high energy electron irradiation experiments at 1.2 MeV also suggested that clustering of point defects occurs near room temperature. An observation in a high resolution image of a small amorphous zone centered at the core of a dislocation is presented as evidence that the nucleation of an amorphous phase is heterogeneous in nature involving clustering or segregation of point defects near existing defects.

  10. Deuterium in crystalline and amorphous silicon

    SciTech Connect

    Borzi, R.; Ma, H.; Fedders, P.A.; Leopold, D.J.; Norberg, R.E.; Boyce, J.B.; Johnson, N.M.; Ready, S.E.; Walker, J.

    1997-07-01

    The authors report deuteron magnetic resonance (DMR) measurements on aged deuterium-implanted single crystal n-type silicon and comparisons with amorphous silicon spectra. The sample film was prepared six years ago by deuteration from a-D{sub 2} plasma and evaluated by a variety of experimental methods. Deuterium has been evolving with time and the present DMR signal shows a smaller deuteron population. A doublet from Si-D configurations along (111) has decreased more than have central molecular DMR components, which include 47 and 12 kHz FWHM gaussians. Transient DMR magnetization recoveries indicate spin lattice relaxation to para-D{sub 2} relaxation centers.

  11. Ionization induced damage in crystalline silicon

    NASA Technical Reports Server (NTRS)

    Meulenberg, A., Jr.

    1977-01-01

    Close examination of the interaction of the energetic knock-on atoms with the local lattice environment reveals a damage mechanism which does satisfy the experimental data on proton irradiation of silicon. A proton-atom interaction with high energy transfer is considered where the proton path is delineated by a trail of ionization, and the silicon ion path is characterized by much heavier ionization terminating in a dense displacement cluster. At collision, many of the silicon electrons are stripped off, and the resulting energetic ion subsequently loses energy rapidly by Coulomb interaction with bound electrons. The rate of energy loss depends on the charge state and velocity of the knock-on ion. For ion energies in excess of 1 MeV, the intensity of ionization is sufficient to permit lattice atoms, stripped of their binding electrons, to reorient randomly before having an opportunity to recombine with electrons and re-establish the lattice. The path of a knock-on ion thus becomes a thin cylinder of amorphous material within the crystal. Amorphous silicon has a Fermi level closer to mid-band than does single crystal silicon, and a strong field therefore, results around this damaged region. The field produces a large depletion region, representing a very large capture cross section for minority carriers.

  12. Single crystal functional oxides on silicon

    PubMed Central

    Bakaul, Saidur Rahman; Serrao, Claudy Rayan; Lee, Michelle; Yeung, Chun Wing; Sarker, Asis; Hsu, Shang-Lin; Yadav, Ajay Kumar; Dedon, Liv; You, Long; Khan, Asif Islam; Clarkson, James David; Hu, Chenming; Ramesh, Ramamoorthy; Salahuddin, Sayeef

    2016-01-01

    Single-crystalline thin films of complex oxides show a rich variety of functional properties such as ferroelectricity, piezoelectricity, ferro and antiferromagnetism and so on that have the potential for completely new electronic applications. Direct synthesis of such oxides on silicon remains challenging because of the fundamental crystal chemistry and mechanical incompatibility of dissimilar interfaces. Here we report integration of thin (down to one unit cell) single crystalline, complex oxide films onto silicon substrates, by epitaxial transfer at room temperature. In a field-effect transistor using a transferred lead zirconate titanate layer as the gate insulator, we demonstrate direct reversible control of the semiconductor channel charge with polarization state. These results represent the realization of long pursued but yet to be demonstrated single-crystal functional oxides on-demand on silicon. PMID:26853112

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

    DOEpatents

    Lowden, R.A.

    1994-04-05

    A process for chemical vapor deposition of crystalline silicon nitride is described 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. 5 figures.

  14. Process for producing amorphous and crystalline silicon nitride

    DOEpatents

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

    1985-11-12

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

  15. Process for producing amorphous and crystalline silicon nitride

    DOEpatents

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

    1985-01-01

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

  16. Crystalline silicon germanium films grown on crystalline silicon substrates by solid phase crystallization

    NASA Astrophysics Data System (ADS)

    Kojima, Yuji; Isomura, Masao

    2015-08-01

    We researched on crystalline silicon-germanium films (c-SiGe) for bottom cells of silicon-based multijunction solar cells. We conducted the epitaxial crystal growth of SiGe with approximately 75% Ge fraction due to solid phase crystallization (SPC) from amorphous silicon-germanium (a-SiGe) precursors on n-type (100) Si substrates. We evaluated the preparation conditions of a-SiGe precursors for the SPC epitaxial growth. The epitaxial growth was successfully conducted and (100)-oriented c-SiGe films were formed. The epitaxial growth was effectively promoted in the a-SiGe precursors prepared at the substrate temperature from 250 to 300 °C, but is not sufficiently promoted in the a-SiGe precursors prepared below 250 °C. The density of a-SiGe precursors is relatively low at the substrate temperature below 250 °C, and the low-density structures cause the impurity incorporation from the air-exposed surface. The impurities are probably the main cause of disturbance of the epitaxial growth. On the other hand, the random crystallization occurred in the SPC of the a-SiGe precursors prepared at 350 °C. The precursors have the slightly crystallized structure and are not suitable for the SPC.

  17. Lithiation of Crystalline Silicon As Analyzed by Operando Neutron Reflectivity.

    PubMed

    Seidlhofer, Beatrix-Kamelia; Jerliu, Bujar; Trapp, Marcus; Hüger, Erwin; Risse, Sebastian; Cubitt, Robert; Schmidt, Harald; Steitz, Roland; Ballauff, Matthias

    2016-08-23

    We present an operando neutron reflectometry study on the electrochemical incorporation of lithium into crystalline silicon for battery applications. Neutron reflectivity is measured from the ⟨100⟩ surface of a silicon single crystal which is used as a negative electrode in an electrochemical cell. The strong scattering contrast between Si and Li due to the negative scattering length of Li leads to a precise depth profile of Li within the Si anode as a function of time. The operando cell can be used to study the uptake and the release of Li over several cycles. Lithiation starts with the formation of a lithium enrichment zone during the first charge step. The uptake of Li can be divided into a highly lithiated zone at the surface (skin region) (x ∼ 2.5 in LixSi) and a much less lithiated zone deep into the crystal (growth region) (x ∼ 0.1 in LixSi). The total depth of penetration was less than 100 nm in all experiments. The thickness of the highly lithiated zone is the same for the first and second cycle, whereas the thickness of the less lithiated zone is larger for the second lithiation. A surface layer of lithium (x ∼ 1.1) remains in the silicon electrode after delithiation. Moreover, a solid electrolyte interface is formed and dissolved during the entire cycling. The operando analysis presented here demonstrates that neutron reflectivity allows the tracking of the kinetics of lithiation and delithiation of silicon with high spatial and temporal resolution. PMID:27447734

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

    SciTech Connect

    Chowdhury, Zahidur R. Kherani, Nazir P.

    2014-12-29

    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 V{sub OC} of 666 mV, J{sub SC} of 29.5 mA-cm{sup −2}, and fill-factor of 69.3%. Reduced parasitic absorption, predominantly in the shorter wavelength range, is confirmed with external quantum efficiency measurement.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Fabricating metal-oxide-semiconductor field-effect transistors on a polyethylene terephthalate substrate by applying low-temperature layer transfer of a single-crystalline silicon layer by meniscus force

    SciTech Connect

    Sakaike, Kohei; Akazawa, Muneki; Nakamura, Shogo; Higashi, Seiichiro

    2013-12-02

    A low-temperature local-layer technique for transferring a single-crystalline silicon (c-Si) film by using a meniscus force was proposed, and an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) was fabricated on polyethylene terephthalate (PET) substrate. It was demonstrated that it is possible to transfer and form c-Si films in the required shape at the required position on PET substrates at extremely low temperatures by utilizing a meniscus force. The proposed technique for layer transfer was applied for fabricating high-performance c-Si MOSFETs on a PET substrate. The fabricated MOSFET showed a high on/off ratio of more than 10{sup 8} and a high field-effect mobility of 609 cm{sup 2} V{sup −1} s{sup −1}.

  1. Magnetotransport of single crystalline YSb.

    PubMed

    Ghimire, N J; Botana, A S; Phelan, D; Zheng, H; Mitchell, J F

    2016-06-15

    We report magnetic field dependent transport measurements on a single crystal of cubic YSb together with first principles calculations of its electronic structure. The transverse magnetoresistance does not saturate up to 9 T and attains a value of 75 000% at 1.8 K. The Hall coefficient is electron-like at high temperature, changes sign to hole-like between 110 and 50 K, and again becomes electron-like below 50 K. First principles calculations show that YSb is a compensated semimetal with a qualitatively similar electronic structure to that of isostructural LaSb and LaBi, but with larger Fermi surface volume. The measured electron carrier density and Hall mobility calculated at 1.8 K, based on a single band approximation, are [Formula: see text] cm(-3) and [Formula: see text] cm(2) Vs(-1), respectively. These values are comparable with those reported for LaBi and LaSb. Like LaBi and LaSb, YSb undergoes a magnetic field-induced metal-insulator-like transition below a characteristic temperature T m, with resistivity saturation below 13 K. Thickness dependent electrical resistance measurements show a deviation of the resistance behavior from that expected for a normal metal; however, they do not unambiguously establish surface conduction as the mechanism for the resistivity plateau. PMID:27160492

  2. Magnetotransport of single crystalline YSb

    NASA Astrophysics Data System (ADS)

    Ghimire, N. J.; Botana, A. S.; Phelan, D.; Zheng, H.; Mitchell, J. F.

    2016-06-01

    We report magnetic field dependent transport measurements on a single crystal of cubic YSb together with first principles calculations of its electronic structure. The transverse magnetoresistance does not saturate up to 9 T and attains a value of 75 000% at 1.8 K. The Hall coefficient is electron-like at high temperature, changes sign to hole-like between 110 and 50 K, and again becomes electron-like below 50 K. First principles calculations show that YSb is a compensated semimetal with a qualitatively similar electronic structure to that of isostructural LaSb and LaBi, but with larger Fermi surface volume. The measured electron carrier density and Hall mobility calculated at 1.8 K, based on a single band approximation, are 6.5× {{10}20} cm‑3 and 6.2× {{10}4} cm2 Vs‑1, respectively. These values are comparable with those reported for LaBi and LaSb. Like LaBi and LaSb, YSb undergoes a magnetic field-induced metal-insulator-like transition below a characteristic temperature T m, with resistivity saturation below 13 K. Thickness dependent electrical resistance measurements show a deviation of the resistance behavior from that expected for a normal metal; however, they do not unambiguously establish surface conduction as the mechanism for the resistivity plateau.

  3. Thermal properties of amorphous/crystalline silicon superlattices.

    PubMed

    France-Lanord, Arthur; Merabia, Samy; Albaret, Tristan; Lacroix, David; Termentzidis, Konstantinos

    2014-09-01

    Thermal transport properties of crystalline/amorphous silicon superlattices using molecular dynamics are investigated. We show that the cross-plane conductivity of the superlattices is very low and close to the conductivity of bulk amorphous silicon even for amorphous layers as thin as ≃ 6 Å. The cross-plane thermal conductivity weakly increases with temperature which is associated with a decrease of the Kapitza resistance with temperature at the crystalline/amorphous interface. This property is further investigated considering the spatial analysis of the phonon density of states in domains close to the interface. Interestingly, the crystalline/amorphous superlattices are shown to display large thermal anisotropy, according to the characteristic sizes of elaborated structures. These last results suggest that the thermal conductivity of crystalline/amorphous superlattices can be phonon engineered, providing new directions for nanostructured thermoelectrics and anisotropic materials in thermal transport. PMID:25105883

  4. New opportunities in crystalline silicon R D

    SciTech Connect

    Menna, P. )

    1999-03-01

    To support the expected growth of the silicon solar cell industry, we believe that research and development (R D) activities should be carried out in the following areas: [ital polysilicon feedstock] for the PV industry; [ital thin-layer silicon] deposition methods, and more [ital environmentally benign] cell and module manufacturing processes. For each of these activities, we identify the main issues that needed to be addressed. [copyright] [ital 1999 American Institute of Physics.

  5. A Single-Crystalline Mesoporous Quartz Superlattice.

    PubMed

    Matsuno, Takamichi; Kuroda, Yoshiyuki; Kitahara, Masaki; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

    2016-05-10

    There has been significant interest in the crystallization of nanostructured silica into α-quartz because of its physicochemical properties. We demonstrate a single-crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α-quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li(+) only on the surface of silica nanospheres is effective for crystallization. PMID:27060365

  6. Surface passivation of heavily boron or phosphorus doped crystalline silicon utilizing amorphous silicon

    NASA Astrophysics Data System (ADS)

    Carstens, K.; Dahlinger, M.

    2016-05-01

    Excellent surface passivation of heavily boron or phosphorus doped crystalline silicon is presented utilizing undoped hydrogenated amorphous silicon (a-Si:H). For passivating boron doped crystalline silicon surfaces, amorphous silicon needs to be deposited at low temperatures 150°C ≤Tdep≤200°C , leading to a high bandgap. In contrast, low bandgap amorphous silicon causes an inferior surface passivation of highly boron doped crystalline silicon. Boron doping in crystalline silicon leads to a shift of the Fermi energy towards the valence band maximum in the undoped a-Si:H. A simulation, implementing dangling bond defects according to the defect pool model, shows this shift in the undoped a-Si:H passivation to be more pronounced if the a-Si:H has a lower bandgap. Hence, the inferior passivation of boron doped surfaces with low bandgap amorphous silicon stems from a lower silicon-hydrogen bond energy due to this shift of the Fermi energy. Hydrogen effusion and ellipsometry measurements support our interpretation.

  7. 77 FR 4764 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... Preliminary Determination in the Countervailing Duty Investigation, 76 FR 81914 (December 29, 2011... 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...

  8. 77 FR 73017 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-07

    ... Determination and Final Affirmative Critical Circumstances Determination, 77 FR 63788 (October 17, 2012). Scope... 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...

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

    SciTech Connect

    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.

  10. Molecular dynamics studies of the bonding properties of amorphous silicon nitride coatings on crystalline silicon

    NASA Astrophysics Data System (ADS)

    Butler, Keith T.; Lamers, Machteld P. W. E.; Weeber, Arthur W.; Harding, John H.

    2011-12-01

    In this paper we present molecular dynamics simulations of silicon nitride, both in bulk and as an interface to crystalline silicon. We investigate, in particular, the bonding structure of the silicon nitride and analyze the simulations to search for defective geometries which have been identified as potential charge carrier traps when silicon nitride forms an interface with silicon semiconductors. The simulations reveal how the bonding patterns in silicon nitride are dependent upon the stoichiometry of the system. Furthermore we demonstrate how having an "interphase", where the nitrogen content in silicon gradually reduces toward pure silicon across a boundary region, as opposed to an interface where there is an abrupt drop in nitrogen concentration at the boundary, can result in significantly different numbers of certain important carrier trap.

  11. Plasmon-loss imaging of chains of crystalline-silicon nanospheres and silicon nanowires

    PubMed

    Kohno; Takeda; Tanaka

    2000-01-01

    Nanostructures in chains of crystalline-silicon nanospheres and silicon nanowires were investigated using energy-filtered transmission electron microscopy (TEM). Observation of the shape of the silicon nanospheres in the chains provided the direct evidence that the chains were formed via the surface oxidation process, which may preferentially work at the necks. The diverse nanostructures in silicon nanowires were revealed, and we found smooth-shaped wires which have periodically modulated silicon cores. Nanostructures in wire-chain transition regions were also investigated for the first time. The wire-chain transition is not a simple junction of a silicon nanowire and a chain of silicon nanospheres, but has a periodically modulated silicon core in the wire region near the transition position. PMID:11108050

  12. Femtosecond studies of plasma formation in crystalline and amorphous silicon

    NASA Astrophysics Data System (ADS)

    Kuett, Waldemar; Esser, Anton; Seibert, Klaus; Lemmer, Uli; Kurz, Heinrich

    1990-08-01

    Transient pump-probe reflectivity measurements are performed on crystalline and amorphous Silicon samples with 50 fs optical pulses at 2 eV. The excited carrier densities range from 1017cm3 up to a few 1021cm3. In both cases the reflectivity signal is dominated by a Drude-like carrier response. Crystalline Silicon shows a distinct subpicosecond feature due to the cooling of the optically excited hot carriers with a time constant of 200-300 fs. Diffusion and Auger-recombination come into play at higher carrier densities. A superlinear increase of instant reflectivity signal with excitation fluence is due to two-photon absorption (TPA) with a TPA-coeffiecient f:37+-5 cm/GW. In amorphous Silicon the TPA process is not observable. The recovery of the induced negative reflectivity changes is dominated by trapping into bandtail and defect states at lower carrier densities. At higher densities a non-radiative recombination process dominates the relaxation of free carriers in both materials. Comparison with crystalline Silicon clearly demonstrates the enhancement of the Auger-recombination process in disordered materials by more than an order of magnitude.

  13. Method of forming crystalline silicon devices on glass

    DOEpatents

    McCarthy, A.M.

    1995-03-21

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

  14. Method of forming crystalline silicon devices on glass

    DOEpatents

    McCarthy, Anthony M.

    1995-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-01

    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.

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

    DOE PAGESBeta

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

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

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

    SciTech Connect

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, 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.

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

    SciTech Connect

    Boccard, Mathieu; Holman, Zachary C.

    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.

  19. Method for fabricating an ultra-low expansion mask blank having a crystalline silicon layer

    DOEpatents

    Cardinale, Gregory F.

    2002-01-01

    A method for fabricating masks for extreme ultraviolet lithography (EUVL) using Ultra-Low Expansion (ULE) substrates and crystalline silicon. ULE substrates are required for the necessary thermal management in EUVL mask blanks, and defect detection and classification have been obtained using crystalline silicon substrate materials. Thus, this method provides the advantages for both the ULE substrate and the crystalline silicon in an Extreme Ultra-Violet (EUV) mask blank. The method is carried out by bonding a crystalline silicon wafer or member to a ULE wafer or substrate and thinning the silicon to produce a 5-10 .mu.m thick crystalline silicon layer on the surface of the ULE substrate. The thinning of the crystalline silicon may be carried out, for example, by chemical mechanical polishing and if necessary or desired, oxidizing the silicon followed by etching to the desired thickness of the silicon.

  20. Low-cost industrial technologies of crystalline silicon solar cells

    SciTech Connect

    Szlufcik, J.; Sivoththaman, S.; Nijs, J.F.; Mertens, R.P.; Overstraeten, R. van

    1997-05-01

    Approximately 2 billion people, mainly in Third World countries, are not connected to an electric grid. The standard, centralized grid development is too expensive and time consuming to solve the energy demand problem. Therefore, there is a need for decentralized renewable energy sources. The main attractiveness of solar cells is that they generate electricity directly from sunlight and can be mounted in modular, stand-alone photovoltaic (PV) systems. Particular attention is paid in this paper to crystalline silicon solar cells, since bulk silicon solar-cell (mono and multi) modules comprise approximately 85% of all worldwide PV module shipments. Energy conversion efficiency as high as 24% has been achieved on laboratory, small-area monocrystalline silicon cells, whereas the typical efficiency of industrial crystalline silicon solar cells is in the range of 13--16%. The market price of PV modules has remained for the last few years in the range of $3.5--4.5/watt peak (Wp). For the photovoltaic industry, the biggest concern is to improve the efficiency and decrease the price of the commercial PV modules. Efficiency-enhancement techniques of commercial cells are described in detail. Adaptation of many high-efficiency features to industrially fabricated solar cells resulted in efficiencies above 17% for multicrystalline and above 18% for monocrystalline silicon solar cells. The latest study shows that increasing the PV market size toward 500 MWp/y and accounting for realistic industrial improvements can lead to a drastic PV module price reduction down to $1/Wp. 120 refs.

  1. MeV-ion beam analysis of the interface between filtered cathodic arc-deposited a-carbon and single crystalline silicon

    SciTech Connect

    Kamwanna, T.; Pasaja, N.; Yu, L.D.; Vilaithong, T.; Anders, A.; Singkarat, S.

    2008-08-01

    Amorphous carbon (a-C) films were deposited on Si(100) wafers by a filtered cathodicvacuum arc (FCVA) plasma source. A negative electrical bias was applied tothe silicon substrate in order to control the incident energy of carbon ions. Effects ofthe electrical bias on the a-C/Si interface characteristics were investigated by usingstandard Rutherford backscattering spectrometry (RBS) in the channeling modewith 2.1-MeV He2+ ions. The shape of the Si surface peaks of the RBS/channelingspectra reflects the degree of interface disorder due to atomic displacement fromthe bulk position of the Si crystal. Details of the analysis method developed aredescribed. It was found that the width of the a-C/Si interface increases linearlywith the substrate bias voltage but not the thickness of the a-C film.

  2. Controlled synthesis of single-crystalline graphene

    SciTech Connect

    Xueshen, Wang Jinjin, Li Qing, Zhong; Yuan, Zhong; Mengke, Zhao; Yonggang, Liu

    2014-03-15

    This paper reports the controlled synthesis of single-crystalline graphene on the back side of copper foil using CH{sub 4} as the precursor. The influence of growth time and the pressure ratio of CH{sub 4}/H{sub 2} on the structure of graphene are examined. An optimized polymer-assisted method is used to transfer the synthesized graphene onto a SiO{sub 2}/Si substrate. Scanning electron microscopy and Raman spectroscopy are used to characterize the graphene.

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

    NASA Technical Reports Server (NTRS)

    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.

  4. Crystalline micro/nanostructures fabrication on silicon using femtosecond laser

    NASA Astrophysics Data System (ADS)

    Deng, Guoliang; Yang, Xianheng; Feng, Guoying; Zhou, Shouhuan

    2015-02-01

    The laser induced micro/ nano-meter size surface structures are fabricated by multi linear polarized femtosecond laser pulses (pulse duration τ=35 fs, wavelength λ=800 nm) irradiation at room temperature(25 ° ) and 400 °. The structures fabricated at these two temperatures show distinct temperature dependence. The grooves, which are parallel to the polarization of the laser light, can be clearly observed at almost all the structured area formed at 400 ° while laser induced period structures(ripples) are the most pronounced surface structure in the crater formed at room temperature. The crystallinity of these surface structures are investigated by using Raman spectroscopy. The Raman spectrum shows that all the structured area formed at 400 ° is crystalline(or poly-crystalline) while amorphous silicon can be observed within the structures formed at room temperature (25 °). These results indicate that temperature is an important parameter to be tuned to tailor the micro/nano-structure fabrication.

  5. Efficient Crystalline Si Solar Cell with Amorphous/Crystalline Silicon Heterojunction as Back Contact: Preprint

    SciTech Connect

    Nemeth, B.; Wang, Q.; Shan, W.

    2012-06-01

    We study an amorphous/crystalline silicon heterojunction (Si HJ) as a back contact in industrial standard p-type five-inch pseudo-square wafer to replace Al back surface field (BSF) contact. The best efficiency in this study is over 17% with open-circuit (Voc) of 0.623 V, which is very similar to the control cell with Al BSF. We found that Voc has not been improved with the heterojunction structure in the back. The typical minority carrier lifetime of these wafers is on the order of 10 us. We also found that the doping levels of p-layer affect the FF due to conductivity and band gap shifting, and an optimized layer is identified. We conclude that an amorphous/crystalline silicon heterojunction can be a very promising structure to replace Al BSF back contact.

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

    DOEpatents

    McCarthy, Anthony M.

    1997-01-01

    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.

  7. Enhanced crystallinity of low temperature deposited silicon films on graphite subtrates

    NASA Technical Reports Server (NTRS)

    Chang, C. A.

    1975-01-01

    The previously developed technique of a sandwich coating for silicon crystallinity enhancement in silicon films deposited at low temperature is applied to graphite substrates. The measured increase in silicon crystallinity is comparable to that observed earlier using a quartz substrate. The distribution of aluminum in the silicon films is determined using Auger spectroscopic depth profiling. Carbon diffusion from the substrate into the silicon film is shown to be negligible at a substrate temperature of 600 C.

  8. Direct electrodeposition of crystalline silicon at low temperatures.

    PubMed

    Gu, Junsi; Fahrenkrug, Eli; Maldonado, Stephen

    2013-02-01

    An electrochemical liquid-liquid-solid (ec-LLS) process that yields crystalline silicon at low temperature (80 °C) without any physical or chemical templating agent has been demonstrated. Electroreduction of dissolved SiCl(4) in propylene carbonate using a liquid gallium [Ga(l)] pool as the working electrode consistently yielded crystalline Si. X-ray diffraction and electron diffraction data separately indicated that the as-deposited materials were crystalline with the expected patterns for a diamond cubic crystal structure. Scanning and transmission electron microscopies further revealed the as-deposited materials (i.e., with no annealing) to be faceted nanocrystals with diameters in excess of 500 nm. Energy-dispersive X-ray spectra further showed no evidence of any other species within the electrodeposited crystalline Si. Raman spectra separately showed that the electrodeposited films on the Ga(l) electrodes were not composed of amorphous carbon from solvent decomposition. The cumulative data support two primary contentions. First, a liquid-metal electrode can serve simultaneously as both a source of electrons for the heterogeneous reduction of dissolved Si precursor in the electrolyte (i.e., a conventional electrode) and a separate phase (i.e., a solvent) that promotes Si crystal growth. Second, ec-LLS is a process that can be exploited for direct production of crystalline Si at much lower temperatures than ever reported previously. The further prospect of ec-LLS as an electrochemical and non-energy-intensive route for preparing crystalline Si is discussed. PMID:23347180

  9. Growth Of Single Crystalline Copper Nanowhiskers

    SciTech Connect

    Kolb, Matthias; Richter, Gunther

    2010-11-24

    Nanowhiskers are defect free single crystals with high aspect ratios and as result exhibit superior physical, e.g. mechanical properties. This paper sheds light on the kinetics of copper nanowhisker growth and thickening. Whisker growth was provoked by covering silicon wafers with a thin carbon film and subsequently coating them with copper by molecular beam epitaxy. The whiskers grown were examined by scanning electron microscopy and the length and diameter were measured as a function of the amount of copper deposited. The experiments show that nanowhisker growth follows Ruth and Hirth's growth model. A fit of the model parameters to the acquired data shows that adsorption of atoms on the substrate and on the whisker surface, with subsequent surface diffusion to the whisker tip, delivers by far the greatest portion of material for whisker growth. Additionally, the experiments demonstrate that the crystallographic orientation of the substrate surface greatly influences the growth rate in the early stage of whisker growth.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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. Back-Contact Crystalline-Silicon Solar Cells and Modules

    SciTech Connect

    Bode, M.D.; Garrett, S.E.; Gee, J.M.; Jimeno, J.C.; Smith, D.D.

    1999-03-10

    This paper summarizes recent progress in the development of back-contact crystalline-silicon (c-Si) solar cells and modules at Sandia National Laboratories. Back-contact cells have potentially improved efficiencies through the elimination of grid obscuration and allow for significant simplifications in the module assembly process. Optimization of the process sequence has improved the efficiency of our back-contact cell (emitter wrap through) from around 12% to near 17% in the past 12 months. In addition, recent theoretical work has elucidated the device physics of emitter wrap-through cells. Finally, improvements in the assembly processing back-contact cells are described.

  12. Solution-processed crystalline silicon double-heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Devkota, Ramesh; Liu, Qiming; Ohki, Tatsuya; Hossain, Jaker; Ueno, Keiji; Shirai, Hajime

    2016-02-01

    Crystalline silicon double-heterojunction solar cells were fabricated using Si/organic and Si/Cs2CO3 heterojunctions. The front heterojunction is formed by spin-coating conductive polymer poly(3,4-ethyenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on n-type Czochralski (CZ) (100) silicon, which separates the photogenerated carriers and blocks the electron dark current while allowing the photocurrent to pass through. The rear heterojunction, formed by spin-coating Cs2CO3 and polyethylenimine (PEI) dissolved in 2-ethoxyethanol and Al metal evaporation, functions as a back surface field that reduces the hole dark current while allowing the electron photocurrent to pass through. The double-heterojunction device showed a power conversion efficiency of 12.7% under AM1.5G simulated solar light exposure.

  13. Inexpensive transparent nanoelectrode for crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    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.

  14. Crystalline silicon solar cells with micro/nano texture

    NASA Astrophysics Data System (ADS)

    Dimitrov, Dimitre Z.; Du, Chen-Hsun

    2013-02-01

    Crystalline silicon solar cells with two-scale texture consisting of random upright pyramids and surface nanotextured layer directly onto the pyramids are prepared and reflectance properties and I-V characteristics measured. Random pyramids texture is produced by etching in an alkaline solution. On top of the pyramids texture, a nanotexture is developed using an electroless oxidation/etching process. Solar cells with two-scale surface texturization are prepared following the standard screen-printing technology sequence. The micro/nano surface is found to lower considerably the light reflectance of silicon. The short wavelengths spectral response (blue response) improvement is observed in micro/nano textured solar cells compared to standard upright pyramids textured cells. An efficiency of 17.5% is measured for the best micro/nano textured c-Si solar cell. The efficiency improvement is found to be due to the gain in both Jsc and Voc.

  15. Inexpensive transparent nanoelectrode for crystalline silicon solar cells.

    PubMed

    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. PMID:27356559

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

    DOEpatents

    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.

  17. Multi-crystalline silicon solidification under controlled forced convection

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    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.

  19. Selective-emitter crystalline silicon solar cells using phosphorus paste

    NASA Astrophysics Data System (ADS)

    Jeong, Kyung Taek; Kang, Min Gu; Song, Hee-eun

    2014-11-01

    Selective-emitter structures have been studied to improve the conversion efficiency of crystalline silicon solar cells. However, such structures require additional complicated processes and incur extra cost. In this work, we used phosphorus paste (P-paste) to form a heavily-doped region beneath the grid and POCl3 to create a shallow emitter area. This method should be convenient to use in the solar-cell industry because it requires only additional P paste printing, compared to the case of homogeneous solar cells. Diffusion parameters including the temperature, diffusion time, and ambient gases were optimized. We observed that the spreading of the P paste was affected by the pyramidal size of the textured wafer due to the low viscosity of the P paste. The pyramidal height of the textured silicon surface was optimized at 3 μm to counterbalance the surface reflectance and the spreading of the P paste. The short-circuit current density of the completed selective emitter solar cell was increased, and an improvement of blue response in the internal quantum efficiency was seen while contact properties such as the fill factor deteriorated due to the spreading of the P paste and the thin emitter on top of the pyramid of the textured silicon surface. Double printing of the P paste was applied to solve this contact problem; a fill factor improvement of 2.4% was obtained.

  20. 77 FR 37877 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-25

    ... Determination of Critical Circumstances, 77 FR 31309 (May 25, 2012), under the section entitled ``Preliminary... 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...

  1. 77 FR 72884 - Crystalline Silicon Photovoltaic Cells and Modules From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-06

    ... in the Federal Register on June 13, 2012 (77 FR 35425). The hearing was held in Washington, DC, on... 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...

  2. 76 FR 78313 - Crystalline Silicon Photovoltaic Cells and Modules From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-16

    ... notice in the Federal Register of October 27, 2011 (76 FR 66748). The conference was held in Washington... 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...

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-13

    ... People's Republic of China: Initiation of Antidumping Duty Investigation, 76 FR 70960 (November 16, 2011... 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...

  4. Multilayer structures of silicon-suboxide embedded in single crystal silicon

    NASA Astrophysics Data System (ADS)

    Pohl, Christoph; Raab, Nicolas; Mitterer, Martin; Tarakina, Nadezda; Breuer, Uwe; Brunner, Karl

    2014-03-01

    Si/SiOx multilayer structures with ultra-thin silicon-suboxide layers are fabricated with molecular beam epitaxy. The silicon surface is oxidized during growth interruptions at an oxygen pressure between 1.0×10-7 mbar and 8.0×10-7 mbar. Overgrowth with Si of the oxidized surface is possible for coverages of a few monolayers of O and improves with increasing substrate temperature. X-ray diffraction shows that the silicon layers are single crystalline. Transmission electron microscopy measurements show that the suboxide layers are ~1 nm thick, pseudomorph, and exhibit crystalline order throughout the layer. In addition, transmission electron microscopy shows that the oxygen concentration is laterally inhomogeneous. The multilayer structures are thermally very stable, as rapid thermal annealing up to 1000 °C shows no influence on the X-ray diffraction patterns.

  5. Crystalline Silicon Short-Circuit Current Degradation Study: Initial Results

    SciTech Connect

    Osterwald, C. R.; Pruett, J.; Moriarty, T.

    2005-02-01

    Following our observation of slow degradation of short-circuit current (Isc) in crystalline silicon (x-Si) modules that was correlated with ultraviolet (UV) exposure dose, we initiated a new study of individual x-Si cells designed to determine the degradation cause. In this paper, we report the initial results of this study, which has accumulated 1056 MJ/m2 of UV dose from 1-sun metal-halide irradiance, equivalent to 3.8 years at our test site. At this time, the control samples are unchanged, the unencapsulated samples have lost about 2% of Isc, and the samples encapsulated in module-style packages have declined from 1% to 3%, depending on the cell technology.

  6. Hydrogen platelets in crystalline silicon - Precursors for the "smart cut"

    SciTech Connect

    Reboredo, Fernando A; Pantelides, Sokrates T

    1999-01-01

    High concentrations of H in crystalline Si are known to induce planar defects (platelets), primarily in the (100) and the (Ill)planes. These platelets are precursors for the so-called "smart cut" technique for fabricating Silicon-On-insulator (SOI) structures. The atomic-scale mechanisms for the nucleation and growth of the H-induced platelets and many other experimental observations have remained elusive. We review recent extensive first-principles calculations in terms of which a comprehensive picture of platelet nucleation and growth has emerged. The theory naturally accounts for the observed preference for (111) and (100) planes, for H release and trapping of H-2 molecules, and other observations. The platelets are arrays of second-neighbor hydrogenated vacancies that do not bind to each other, but their formation is due to energetically preferred reaction pathways.

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

    NASA Astrophysics Data System (ADS)

    Abdulraheem, Yaser; Gordon, Ivan; Bearda, Twan; Meddeb, Hosny; Poortmans, Jozef

    2014-05-01

    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

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

    SciTech Connect

    Abdulraheem, Yaser; Gordon, Ivan; Bearda, Twan; Meddeb, Hosny; Poortmans, Jozef

    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. Research Opportunities in Crystalline Silicon Photovoltaics for the 21st Century

    SciTech Connect

    Atwater, Harry A.; Ciszek, Ted; Feldman, Leonard C.; Gee, James; Rohatgi, Ajeet; Sopori, Bhushan

    1999-07-28

    Crystalline silicon continues to be the dominant semiconductor material used for terrestrial photovoltaics. This paper discusses the scientific issues associated with silicon photovoltaics processing, and cell design that may yield cell and module performance improvements that are both evolutionary and revolutionary in nature. We first survey critical issues in ''thick'' crystalline silicon photovoltaics, including novel separations processes for impurity removal, impurity and defect fundamentals, interface passivation, the role of hydrogen. Second, we outline emerging opportunities for creation of a very different ''thin-layer'' silicon cell structure, including the scientific issues and engineering challenges associated with thin-layer silicon processing and cell design.

  10. Single Molecule Study of Cellulase Hydrolysis of Crystalline Cellulose

    SciTech Connect

    Liu, Y.-S.; Luo, Y.; Baker, J. O.; Zeng, Y.; Himmel, M. E.; Smith, S.; Ding, S.-Y.

    2009-12-01

    This report seeks to elucidate the role of cellobiohydrolase-I (CBH I) in the hydrolysis of crystalline cellulose. A single-molecule approach uses various imaging techniques to investigate the surface structure of crystalline cellulose and changes made in the structure by CBH I.

  11. LiBr treated porous silicon used for efficient surface passivation of crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Zarroug, Ahmed; Haddadi, Ikbel; Derbali, Lotfi; Ezzaouia, Hatem

    2015-04-01

    A simple but effective passivation method of both front and rear surfaces using porous silicon (PS) has been developed. This paper investigates the effect of LiBr on the passivation of PS. The immersion of as-etched PS in dilute LiBr solution followed by an annealing in an infrared furnace, under a controlled atmosphere at different temperatures, led to the passivation of the PS layer and the improvement of the electronic properties of the crystalline silicon substrates. The influence of substrate temperature was investigated, since the processed wafers were found to be sensitive to heat, which in turn was optimized to have a gettering effect. The bromide of lithium can effectively saturate dangling bonds and hence contributed to the formation of a stable passivation film, at both front and back surfaces. Such a reaction was found to have a beneficial effect on the passivation process of the PS layer grown on both sides. The obtained results exhibited a significant improvement of the minority carrier lifetime, which is an important parameter that defines the quality of crystalline silicon substrates, and an apparent enhancement of its photoluminescence (PL). The internal quantum efficiency was investigated and found to be significantly improved. The qualitative effect of the above-mentioned procedure proved a significant enhancement of the electronic quality of the treated substrates.

  12. The crystalline-silicon photovoltaic R&D project at NREL and SNL

    SciTech Connect

    Gee, J.M.; Ciszek, T.F.

    1996-12-31

    This paper summarizes the U.S. Department of Energy R&D program in crystalline-silicon photovoltaic technology, which is jointly managed by Sandia National Laboratories and National Renewable Energy Laboratory. This program features a balance of basic an d applied R&D, and of university, industry, and national laboratory R&D. The goal of the crystalline-silicon R&D program is to accelerate the commercial growth of crystalline-silicon photovoltaic technology, and four strategic objectives were identified to address this program goal. Technical progress towards meeting these objectives is reviewed.

  13. Temperature-dependent minority carrier lifetime of crystalline silicon wafers passivated by high quality amorphous silicon oxide

    NASA Astrophysics Data System (ADS)

    Inaba, Masahiro; Todoroki, Soichiro; Nakada, Kazuyoshi; Miyajima, Shinsuke

    2016-04-01

    We investigated the effects of annealing on the temperature-dependent minority carrier lifetime of a crystalline silicon wafer passivated by hydrogenated amorphous silicon oxide. The annealing significantly affects the lifetime and its temperature dependence. Our device simulations clearly indicate that valence band offset significantly affects the temperature dependence. We also found a slight increase in the interface defect density after annealing.

  14. Crystalline Silicon/Graphene Oxide Hybrid Junction Solar Cells

    NASA Astrophysics Data System (ADS)

    Liu, Qiming; Wanatabe, Fumiya; Hoshino, Aya; Ishikawa, Ryo; Gotou, Takuya; Ueno, Keiji; Shirai, Hajime

    2012-10-01

    Soluble graphene oxide (GO) and plasma-reduced (pr-) GO were investigated using crystalline silicon (c-Si) (100)/GO/pr-GO hybrid junction solar cells. Their photovoltaic performances were compared with those of c-Si/GO/pristine conductive poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) heterojunction and c-Si/PEDOT:PSS:GO composite devices. The c-Si/GO/pr-GO and conductive PEDOT:PSS/Al heterojunction solar cells showed power conversion efficiencies of 6.5 and 8.2%, respectively, under illumination with AM 1.5 G 100 mW/cm2 simulated solar light. A higher performance of 10.7% was achieved using the PEDOT:PSS:GO (12.5 wt %) composite device. These findings imply that soluble GO, pr-GO, and the PEDOT:PSS:GO composite are promising materials as hole transport and transparent conductive layers for c-Si/organic hybrid junction solar cells.

  15. A vacancy-related muon species in crystalline silicon

    NASA Astrophysics Data System (ADS)

    Schefzik, M.; Scheuermann1, R.; Schimmele, L.; Seeger, A.; Herlach, D.; Kormann, O.; Major, J.; Röck, A.

    2000-08-01

    A new muonium centre, termed Mu V, with weak hyperfine interaction has been discovered recently in crystalline silicon in longitudinal field quenching μSR (LFQ) experiments (Schefzik et al., Solid State Commun. 107 (1998) 395). The signatures of this species were found in intrinsic, but not in doped samples (dopant concentration larger than 10 16 cm-3). The centre is not formed promptly but results from a reaction in which normal muonium transforms into the novel species. Since from LFQ experiments one can obtain only a rough estimate of the hyperfine tensor of Mu V it is now determined from zero-field (ZF) μSR experiments. The hyperfine interaction is found to be axially symmetric around the <1 1 0> crystallographic axis with small hyperfine parameters. Properly rescaled it essentially agrees with the hyperfine tensor of the hydrogen centre VH, which has been discovered recently by Bech Nielsen et al. (Phys. Rev. Lett. 79 (1997) 1507) and which has been attributed to hydrogen trapped in vacancies. Accordingly Mu V is interpreted as muonium trapped in a vacancy, in agreement with the interpretation given on the basis of the earlier LFQ data.

  16. Evidence for a novel muon species in crystalline silicon

    NASA Astrophysics Data System (ADS)

    Schefzik, M.; Scheuermann, R.; Schimmele, L.; Schmidl, J.; Seeger, A.; Herlach, D.; Kormann, O.; Major, J.; Röck, A.

    1998-07-01

    Investigations of positive muons ( μ+) in crystalline silicon employing the longitudinal field-quenching (LFQ) technique give strong evidence for the existence of a novel paramagnetic muon species with a small anisotropic hyperfine interaction. It adds to the list of known muon species, i.e., normal and anomalous muonium and the diamagnetic muon species. The signatures of the novel species are found in intrinsic but not in doped samples (dopant concentration about 10 16 cm -3). The novel species is not formed promptly but results from a reaction in which normal muonium transforms into the novel species. The reaction rate constant at 10 K was found to be about 10 6 s -1. The hyperfine coupling of the novel paramagnetic muon species corresponds, after rescaling, to that of a hydrogen center termed VH, which has been discovered recently by Bech Nielsen et al. ( Phys. Rev. Lett., 79, 1997, 1507) and which has been attributed to hydrogen trapped in vacancies. The LFQ data are tentatively interpreted in terms of trapping of normal muonium in vacancies that are created during the slowing-down of implanted muons close to the end of their stopping tracks.

  17. Aluminum gettering in single and multicrystalline silicon

    SciTech Connect

    McHugo, S.A.; Hieslmair, H.; Weber, E.R.

    1995-08-01

    Al gettering has been performed on integrated circuit (I.C.) quality silicon and a variety of single and multicrystalline silicon solar cell materials. The minority carrier diffusion length, Ln, has been used to quantify the gettering response. Vast differences in response to the Al gettering treatment are observed between the I.C. quality silicon and the solar cell materials. The I.C. silicon generally responds well while the solar cell silicon performance progressively degrades with increasing gettering temperature. Preliminary data shows that by performing a Rapid Thermal Annealing treatment prior to the Al gettering, an improved or further degraded Ln emerges in solar cell material depending on the material`s manufacturer. We explain these observed phenomena by suggesting that Al gettering in solar cell silicon is an impurity emission-limited process while for I.C. quality silicon it is diffusion limited.

  18. Crack Growth in Single-Crystal Silicon

    NASA Technical Reports Server (NTRS)

    Chen, C. P.; Leipold, M. H.

    1986-01-01

    Report describes experiments on crack growth in single-crystal silicon at room temperature in air. Crack growth in (111) cleavage plane of wafers, 50 by 100 by 0.76 mm in dimension, cut from Czochralski singlecrystal silicon studied by double-torsion load-relaxation method and by acoustic-emission measurements. Scanning electron microscopy and X-ray topography also employed. Results aid in design and fabrication of silicon photovoltaic and microelectronic devices.

  19. 77 FR 63788 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-17

    ... the People's Republic of China: Preliminary Affirmative Countervailing Duty Determination, 77 FR 17439... Critical Circumstances, 77 FR 5487 (February 3, 2012) (Preliminary Critical Circumstances Determination... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into...

  20. A pseudo-single-crystalline germanium film for flexible electronics

    SciTech Connect

    Higashi, H.; Yamada, S.; Kanashima, T.; Hamaya, K.; Kasahara, K.; Park, J.-H.; Miyao, M.; Kudo, K.; Okamoto, H.; Moto, K.; Tsunoda, I.

    2015-01-26

    We demonstrate large-area (∼600 μm), (111)-oriented, and high-crystallinity, i.e., pseudo-single-crystalline, germanium (Ge) films at 275 °C, where the temperature is lower than the softening temperature of a flexible substrate. A modulated gold-induced layer exchange crystallization method with an atomic-layer deposited Al{sub 2}O{sub 3} barrier and amorphous-Ge/Au multilayers is established. From the Raman measurements, we can judge that the crystallinity of the obtained Ge films is higher than those grown by aluminum-induced-crystallization methods. Even on a flexible substrate, the pseudo-single-crystalline Ge films for the circuit with thin-film transistor arrays can be achieved, leading to high-performance flexible electronics based on an inorganic-semiconductor channel.

  1. Scalable High-Efficiency Thin Crystalline Silicon Photovoltaic Cells Enabled by Light-Trapping Nanostructures

    SciTech Connect

    Chen, Gang; Branham, Matthew S.; Hsu, Wei-Chun; Yerci, Selcuk

    2014-09-02

    This report summarizes the research activities of the Chen group at MIT over the last two years pertaining to our research effort developing and proving light-trapping designs for ultrathin crystalline silicon solar cells. We present a new world record efficiency for a sub-20-micron crystalline silicon device, as well as details on the combined photonic/electronic transport simulation we developed for photovoltaic applications.

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

    PubMed Central

    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. PMID:25024687

  3. Probing the low thermal conductivity of single-crystalline porous Si nanowires

    NASA Astrophysics Data System (ADS)

    Zhao, Yunshan; Lina Yang Collaboration; Lingyu Kong Collaboration; Baowen Li Collaboration; John T L Thong Collaboration; Kedar Hippalgaonkar Collaboration

    Pore-like structures provide a novel way to reduce the thermal conductivity of silicon nanowires, compared to both smooth-surface VLS nanowires and rough EE nanowires. Because of enhanced phonon scattering with interface and decrease in phonon transport path, the porous nanostructures show reduction in thermal conductance by few orders of magnitude. It proves to be extremely challenging to evaluate porosity accurately in an experimental manner and further understand its effect on thermal transport. In this study, we use the newly developed electron-beam based micro-electrothermal device technique to study the porosity dependent thermal conductivity of mesoporous silicon nanowires that have single-crystalline scaffolding. Based on the Casino simulation, the power absorbed by the nanowire, coming from the loss of travelling electron energy, has a linear relationship with it cross section. The relationship has been verified experimentally as well. Monte Carlo simulation is carried out to theoretically predict the thermal conductivity of silicon nanowires with a specific value of porosity. These single-crystalline porous silicon nanowires show extremely low thermal conductivity, even below the amorphous limit. These structures together with our experimental techniques provide a particularly intriguing platform to understand the phonon transport in nanoscale and aid the performance improvement in future nanowires-based devices.

  4. A single crystalline InP nanowire photodetector

    NASA Astrophysics Data System (ADS)

    Yan, Xin; Li, Bang; Wu, Yao; Zhang, Xia; Ren, Xiaomin

    2016-08-01

    Single crystalline nanowires are critical for achieving high-responsivity, high-speed, and low-noise nanoscale photodetectors. Here, we report a metal-semiconductor-metal photodetector based on a single crystalline InP nanowire. The nanowires are grown by a self-catalyzed method and exhibit stacking-fault-free zinc blende crystal structure. The nanowire exhibits a typical n-type semiconductor property and shows a low room temperature dark current of several hundred pA at moderate biases. A photoresponsivity of 6.8 A/W is obtained at a laser power density of 0.2 mW/cm2. This work demonstrates that single crystalline InP nanowires are good candidates for future optoelectronic device applications.

  5. Magnetotransport of single crystalline NbAs

    DOE PAGESBeta

    Ghimire, N. J.; Luo, Yongkang; Neupane, M.; Williams, D. J.; Bauer, E. D.; Ronning, F.

    2015-03-27

    We report transport measurement in zero and applied magnetic field on a single crystal of NbAs. Transverse and longitudinal magnetoresistance in the plane of this tetragonal structure does not saturate up to 9 T. In the transverse configuration (H ∥ c, I ⊥ c) it is 230,000% at 2 K. The Hall coefficient changes sign from hole-like at room temperature to electron-like below ~150 K. The electron carrier density and mobility calculated at 2 K based on a single band approximation are 1.8 × 1019 cm-3 and 3.5 × 105 cm2/Vs, respectively. These values are similar to reported values formore » TaAs and NbP, and further emphasize that this class of noncentrosymmetric, transition-metal monopnictides is a promising family to explore the properties of Weyl semimetals and the consequences of their novel electronic structure.« less

  6. Polycrystalline graphene with single crystalline electronic structure.

    PubMed

    Brown, Lola; Lochocki, Edward B; Avila, José; Kim, Cheol-Joo; Ogawa, Yui; Havener, Robin W; Kim, Dong-Ki; Monkman, Eric J; Shai, Daniel E; Wei, Haofei I; Levendorf, Mark P; Asensio, María; Shen, Kyle M; Park, Jiwoong

    2014-10-01

    We report the scalable growth of aligned graphene and hexagonal boron nitride on commercial copper foils, where each film originates from multiple nucleations yet exhibits a single orientation. Thorough characterization of our graphene reveals uniform crystallographic and electronic structures on length scales ranging from nanometers to tens of centimeters. As we demonstrate with artificial twisted graphene bilayers, these inexpensive and versatile films are ideal building blocks for large-scale layered heterostructures with angle-tunable optoelectronic properties. PMID:25207847

  7. Damage at hydrogenated amorphous/crystalline silicon interfaces by indium tin oxide overlayer sputtering

    NASA Astrophysics Data System (ADS)

    Demaurex, Bénédicte; De Wolf, Stefaan; Descoeudres, Antoine; Charles Holman, Zachary; Ballif, Christophe

    2012-10-01

    Damage of the hydrogenated amorphous/crystalline silicon interface passivation during transparent conductive oxide sputtering is reported. This occurs in the fabrication process of silicon heterojunction solar cells. We observe that this damage is at least partially caused by luminescence of the sputter plasma. Following low-temperature annealing, the electronic interface properties are recovered. However, the silicon-hydrogen configuration of the amorphous silicon film is permanently changed, as observed from infra-red absorbance spectra. In silicon heterojunction solar cells, although the as-deposited film's microstructure cannot be restored after sputtering, no significant losses are observed in their open-circuit voltage.

  8. Single-crystalline monolayer and multilayer graphene nano switches

    SciTech Connect

    Li, Peng; Cui, Tianhong; Jing, Gaoshan; Zhang, Bo; Sando, Shota

    2014-03-17

    Growth of monolayer, bi-layer, and tri-layer single-crystalline graphene (SCG) using chemical vapor deposition method is reported. SCG's mechanical properties and single-crystalline nature were characterized and verified by atomic force microscope and Raman spectroscopy. Electro-mechanical switches based on mono- and bi-layer SCG were fabricated, and the superb properties of SCG enable the switches to operate at pull-in voltage as low as 1 V, and high switching speed about 100 ns. These devices exhibit lifetime without a breakdown of over 5000 cycles, far more durable than any other graphene nanoelectromechanical system switches reported.

  9. Nonvolatile resistive switching in single crystalline ZnO nanowires.

    PubMed

    Yang, Yuchao; Zhang, Xiaoxian; Gao, Min; Zeng, Fei; Zhou, Weiya; Xie, Sishen; Pan, Feng

    2011-04-01

    We demonstrate nonvolatile resistive switching in single crystalline ZnO nanowires with high ON/OFF ratios and low threshold voltages. Unlike the mechanism of continuous metal filament formation along grain boundaries in polycrystalline films, the resistive switching in single crystalline ZnO nanowires is speculated to be induced by the formation of a metal island chain on the nanowire surface. Resistive memories based on bottom-up semiconductor nanowires hold potential for next generation ultra-dense nonvolatile memories. PMID:21394361

  10. Magnetoresistance in single crystalline chromium sulfides

    NASA Astrophysics Data System (ADS)

    Lee, K. D.; Won, C. J.; Song, K. M.; Hur, N.

    2011-03-01

    We studied the anisotropic magnetic and magnetotransport properties of Cr2S3 single crystals grown by using the vapor transport method. Large magnetoresistance of ˜ 46% was observed in 9 T magnetic field applied perpendicular to the c axis near the Néel temperature TN ≈ 118 K. Comparison of electric and magnetic properties of Cr2S3 crystals with different sulfur deficiencies suggested that the electron doping by the sulfur deficiency does not contribute to weak ferromagnetism. The correlation between the field-dependent magnetization and resistivity was analyzed by the polaron hopping model of magnetotransport in Cr2S3.

  11. Magnetotransport of single crystalline NbAs

    SciTech Connect

    Ghimire, N. J.; Luo, Yongkang; Neupane, M.; Williams, D. J.; Bauer, E. D.; Ronning, F.

    2015-03-27

    We report transport measurement in zero and applied magnetic field on a single crystal of NbAs. Transverse and longitudinal magnetoresistance in the plane of this tetragonal structure does not saturate up to 9 T. In the transverse configuration (H ∥ c, I ⊥ c) it is 230,000% at 2 K. The Hall coefficient changes sign from hole-like at room temperature to electron-like below ~150 K. The electron carrier density and mobility calculated at 2 K based on a single band approximation are 1.8 × 1019 cm-3 and 3.5 × 105 cm2/Vs, respectively. These values are similar to reported values for TaAs and NbP, and further emphasize that this class of noncentrosymmetric, transition-metal monopnictides is a promising family to explore the properties of Weyl semimetals and the consequences of their novel electronic structure.

  12. Synthesis of single-crystalline anisotropic gold nano-crystals via chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Manna, Sohini; Kim, Jong Woo; Takahashi, Yukiko; Shpyrko, Oleg G.; Fullerton, Eric E.

    2016-05-01

    We report on a novel one-step catalyst-free, thermal chemical vapor deposition procedure to synthesize gold nanocrystals on silicon substrates. This approach yields single-crystal nanocrystals with various morphologies, such as prisms, icosahedrons, and five-fold twinned decahedrons. Our approach demonstrates that high-quality anisotropic crystals composed of fcc metals can be produced without the need for surfactants or templates. Compared with the traditional wet chemical synthesis processes, our method enables direct formation of highly pure and single crystalline nanocrystals on solid substrates which have applications in catalysis. We investigated the evolution of gold nanocrystals and established their formation mechanism.

  13. Low temperature growth of crystalline magnesium oxide on hexagonal silicon carbide (0001) by molecular beam epitaxy

    SciTech Connect

    Goodrich, T. L.; Parisi, J.; Cai, Z.; Ziemer, K. S.

    2007-01-22

    Magnesium oxide (111) was grown epitaxially on hexagonal silicon carbide (6H-SiC) (0001) substrates at low temperatures by molecular beam epitaxy and a remote oxygen plasma source. The films were characterized by reflection high-energy electron diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy. Crystal structure, morphology, and growth rate of the magnesium oxide (MgO) films were found to be dependent on the magnesium flux, indicating a magnesium adsorption controlled growth mechanism. The single crystalline MgO thin films had an epitaxial relationship where MgO (111) parallel 6H-SiC (0001) and were stable in both air and 10{sup -9} Torr up to 1023 K.

  14. Wet-texturing process for a thin crystalline silicon solar cell at low cost with high efficiency

    NASA Astrophysics Data System (ADS)

    Han, Kyu-Min; Yoo, Jin-Su

    2014-04-01

    In the wet-texturing process, a smaller etch depth of 8 µm was established on each side of the thin silicon wafer. Formation of a very small size (1-3 µm) pyramidal structure was confirmed on a thin c-Si surface through the use of SEM micrographs. For this silicon surface with small pyramidal structures, a surface reflectance of 15.14% was observed. Saw damage removal was employed for the second and the third sets of silicon wafers in a NaOH (8 wt%) solution, and the wafers were then textured in a mixture of NaOH (1.5 wt%), de-ionized water and Isopropyl alcohol (IPA, 6-8 wt%) at 80 °C for 18 min and 24 min, respectively. In this process, the scraped depths were 16 and 26 µm on each side of the second and the third sets of silicon wafers, and the pyramidal sizes were 4-9 µm and 9-12 µm respectively. We found that the reflectances of these sets of wafers were 14.98% and 14.78%, respectively. Our novel approach of ultrasonic cleaning, hot de-ionized water treatment, and texturing for thin c-Si wafers yielded small-sized (1-3 µm) uniform pyramidal structure that were stable and suitable for metalized screen printing. Even though the reflectance was high for the first set of wafers the illuminated current-voltage (LIV) measurements confirmed the wafers' superiority over the conventional textured c-Si solar cells in terms of the open-circuit voltage and the fill factor. The small-size pyramidal-structured thin single-crystalline silicon solar cells showed a 17.9% efficiency. Since no NaOH solution was used for saw damage removal in the first set of silicon wafers, the production cost for commercial production of large-area single-crystalline silicon solar cells was reduced by nearly 20%.

  15. Effect of scandium on the optical properties of crystalline silicon material.

    PubMed

    Dong, Xiao; Wang, Yongyong; Li, Xueping; Li, Yingying

    2016-09-01

    We have studied the optical properties of Sc-hyperdoped crystalline silicon based on quantum calculations. We have designed several probable configurations and found that the interstitial atomic positions of Sc (ScI, ScSI, ScTI, ScHI) are stable in the silicon matrix and can largely extend the absorption range of silicon from visible to infrared. The sub-band gap light absorption is attributed to the change of band structures of silicon and its intensity depends on the atomic concentration of Sc in silicon. The special effect of Sc on the properties of silicon will extend the sensitivity of silicon-based photodetectors to near infrared wavelength range. PMID:27607729

  16. Process optimization for lattice-selective wet etching of crystalline silicon structures

    NASA Astrophysics Data System (ADS)

    Dixson, Ronald G.; Guthrie, William F.; Allen, Richard A.; Orji, Ndubuisi G.; Cresswell, Michael W.; Murabito, Christine E.

    2016-01-01

    Lattice-selective etching of silicon is used in a number of applications, but it is particularly valuable in those for which the lattice-defined sidewall angle can be beneficial to the functional goals. A relatively small but important niche application is the fabrication of tip characterization standards for critical dimension atomic force microscopes (CD-AFMs). CD-AFMs are commonly used as reference tools for linewidth metrology in semiconductor manufacturing. Accurate linewidth metrology using CD-AFM, however, is critically dependent upon calibration of the tip width. Two national metrology institutes and at least two commercial vendors have explored the development of tip calibration standards using lattice-selective etching of crystalline silicon. The National Institute of Standards and Technology standard of this type is called the single crystal critical dimension reference material. These specimens, which are fabricated using a lattice-plane-selective etch on (110) silicon, exhibit near vertical sidewalls and high uniformity and can be used to calibrate CD-AFM tip width to a standard uncertainty of less than 1 nm. During the different generations of this project, we evaluated variations of the starting material and process conditions. Some of our starting materials required a large etch bias to achieve the desired linewidths. During the optimization experiment described in this paper, we found that for potassium hydroxide etching of the silicon features, it was possible to independently tune the target linewidth and minimize the linewidth nonuniformity. Consequently, this process is particularly well suited for small-batch fabrication of CD-AFM linewidth standards.

  17. Novel low cost chemical texturing for very large area industrial multi-crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, U.; Dhungel, S. K.; Kim, K.; Manna, U.; Basu, P. K.; Kim, H. J.; Karunagaran, B.; Lee, K. S.; Yoo, J. S.; Yi, J.

    2005-09-01

    Multi-crystalline silicon surface etching without grain-boundary delineation is a challenging task for the fabrication of high efficiency solar cells. The use of sodium hydroxide-sodium hypochlorite (NaOH-NaOCl) solution for texturing a multi-crystalline silicon wafer surface in a solar cell fabrication line is reported in this paper. The optimized etching solution of NaOH-NaOCl does not have any effect on multi-crystalline silicon grain boundaries and it also has excellent isotropic etch characteristics, which ultimately helps to achieve higher values of performance parameters, especially the open circuit voltage (Voc) and fill factor (FF), than those in the case of conventional silicon texturing. Easy control over the reaction of the NaOH-NaOCl solution is also one of the major advantages due to which sophistication in controlling the temperature of the etching bath is not required for the industrial batch process. The FTIR analysis of the silicon surface after etching with the current approach shows the formation of Si-Cl bonds, which improves the quality of the diffused junction due to chlorine gettering during diffusion. We are the first to report 14-14.5% efficiency of very large area (150 mm × 150 mm) multi-crystalline silicon solar cells using a NaOH-NaOCl texturing approach in an industrial production line with a yield greater than 95%.

  18. Influence of different seed materials on multi-crystalline silicon ingot properties

    NASA Astrophysics Data System (ADS)

    Reimann, C.; Trempa, M.; Lehmann, T.; Rosshirt, K.; Stenzenberger, J.; Friedrich, J.; Hesse, K.; Dornberger, E.

    2016-01-01

    Different silicon feedstock materials, Single Crystalline Crushed (SCS), Fluidized-Bed-Reactor (FBR) and Siemens (SIE) feedstock, were used as seeding layer for growing cylindrical shaped, high performance multi-crystalline ingots with a weight of 1.2 kg. Within the investigations a systematic variation of the particle size of the seeding material in the range of <1 mm up to 15 mm was performed. Grain size, grain orientation, and grain boundary type were evaluated at different ingot heights. These results show clearly, that the microstructure size, respectively the particle size for the crushed single crystalline material, determines the resulting grain structure in the ingot near the seeding position. If the microstructure size is equal to the particle size, as it is the case for the SCS material, the particle size has a significant influence on grain size, grain orientation, and grain boundary distribution. With increasing average particle size of the SCS seed material the grain size increases, the grain orientation distribution becomes less uniform, and the random grain boundary length fraction decreases. If the microstructure size is smaller than the particle size, as it is the case for FBR and SIE feedstock materials, the particle size has no influence on the initial grain structure of the ingot. For FBR and SIE seeding material, small grains, with a homogeneous orientation distribution and a high random grain boundary length fraction are obtained. Therefore, all FBR and all SIE seeding materials, as well as the SCS with particle size <1 mm, show lowest fractions of defected areas at about the same level which were determined by etch pit analysis.

  19. Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights

    SciTech Connect

    Razek, Sara Abdel; Swillam, Mohamed A.; Allam, Nageh K.

    2014-05-21

    Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H{sub 2}O{sub 2} electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650 nm and lengths from 8 to 18 μm. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ∼670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ∼660 nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.

  20. Modeling of optical spectroscopy for the crystalline silicon

    NASA Astrophysics Data System (ADS)

    Liu, Changshi

    2014-03-01

    The paper is aimed at modeling optical spectra of silicon. Optical spectra of silicon are described with the Logistic function. A satisfactory agreement between the measured and the modeled optical spectra are obtained. The minimum magnitude of the correlation coefficient between experiment and theoretical results is 0.994, and the maximum average relative error is 4.21%. Meanwhile, it is found that the band gap of semiconductor may be determined by fitting absorption coefficient as a function of wavelength. Lastly, the mathematical relationships between the parameters, which are used to link the reflectance of silicon and wavelength, and radiation fluency, are obtained. Consequently, the change of reflectance for silicon can be predicted by both wavelength and dose radiation fluency only one function. All results in this paper are of interest from both optics and materials point of view.

  1. New Opportunities in Crystalline Silicon R&D

    SciTech Connect

    Tsuo, Y. S.; Wang, T. H.; Ciszek, T. F.; Menna, P.

    1998-10-06

    To support the expected growth of the silicon solar cell industry, we believe that research and development (R&D) activities should be carried out in the following areas: polysilicon feedstock for the PV industry; thin-layer silicon deposition methods, and more environmentally benign cell and module manufacturing processes. For each of these activities, we identify the main issues that needed to be addressed.

  2. Multiscaled hierarchical nanostructures for enhancing the conversion efficiency of crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Bingfa; Qiu, Shenyu; Hu, Ruiyi; Liao, Yuanbin; Chen, Nan; Du, Guoping

    2012-10-01

    High-performance antireflection structure is critical for enhancing the conversion efficiency of solar cells. One of the most effective antireflection techniques for solar cells is the introduction of nanostructures to the cells. In this work, we prepared multiscaled hierarchical Er-doped ZnO nanostructures on the plasma enhanced chemical vapor deposited silicon nitride-coated texturized single crystalline silicon solar cells for antireflection. The multiscaled hierarchical Er-doped ZnO nanostructures were needle-like nanotip arrays, and they were grown using the hydrothermal method. The dependence of microstructure and antireflection performance of the multiscaled hierarchical Er-doped ZnO nanostructures on the growth time were studied. It was shown that longer growth time resulted in greater length and diameter for the Er-doped ZnO nanostructures. For longer growth time, the needle-like tips of the multiscaled hierarchical Er-doped ZnO nanostructures were found to transform to flat tops, which greatly degraded their antireflection performance. An optimal growth time for the multiscaled hierarchical Er-doped ZnO nanostructures was determined, and a large enhancement in the photovoltaic performance of sc-Si solar cells was resulted.

  3. Solution-based synthesis of crystalline silicon from liquid silane through laser and chemical annealing.

    PubMed

    Iyer, Ganjigunte R S; Hobbie, Erik K; Guruvenket, Srinivasan; Hoey, Justin M; Anderson, Kenneth J; Lovaasen, John; Gette, Cody; Schulz, Douglas L; Swenson, Orven F; Elangovan, Arumugasamy; Boudjouk, P

    2012-05-01

    We report a solution process for the synthesis of crystalline silicon from the liquid silane precursor cyclohexasilane (Si(6)H(12)). Polysilane films were crystallized through thermal and laser annealing, with plasma hydrogenation at atmospheric pressure generating further structural changes in the films. The evolution from amorphous to microcrystalline is characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and impedance spectroscopy. A four-decade enhancement in the electrical conductivity is attributed to a disorder-order transition in a bonded Si network. Our results demonstrate a potentially attractive approach that employs a solution process coupled with ambient postprocessing to produce crystalline silicon thin films. PMID:22545711

  4. Single-crystalline nanoporous Nb2O5 nanotubes

    PubMed Central

    2011-01-01

    Single-crystalline nanoporous Nb2O5 nanotubes were fabricated by a two-step solution route, the growth of uniform single-crystalline Nb2O5 nanorods and the following ion-assisted selective dissolution along the [001] direction. Nb2O5 tubular structure was created by preferentially etching (001) crystallographic planes, which has a nearly homogeneous diameter and length. Dense nanopores with the diameters of several nanometers were created on the shell of Nb2O5 tubular structures, which can also retain the crystallographic orientation of Nb2O5 precursor nanorods. The present chemical etching strategy is versatile and can be extended to different-sized nanorod precursors. Furthermore, these as-obtained nanorod precursors and nanotube products can also be used as template for the fabrication of 1 D nanostructured niobates, such as LiNbO3, NaNbO3, and KNbO3. PMID:21711650

  5. Single-crystalline nanoporous Nb2O5 nanotubes.

    PubMed

    Liu, Jun; Xue, Dongfeng; Li, Keyan

    2011-01-01

    Single-crystalline nanoporous Nb2O5 nanotubes were fabricated by a two-step solution route, the growth of uniform single-crystalline Nb2O5 nanorods and the following ion-assisted selective dissolution along the [001] direction. Nb2O5 tubular structure was created by preferentially etching (001) crystallographic planes, which has a nearly homogeneous diameter and length. Dense nanopores with the diameters of several nanometers were created on the shell of Nb2O5 tubular structures, which can also retain the crystallographic orientation of Nb2O5 precursor nanorods. The present chemical etching strategy is versatile and can be extended to different-sized nanorod precursors. Furthermore, these as-obtained nanorod precursors and nanotube products can also be used as template for the fabrication of 1 D nanostructured niobates, such as LiNbO3, NaNbO3, and KNbO3. PMID:21711650

  6. The future of crystalline silicon technology in the US Department of Energy program

    NASA Technical Reports Server (NTRS)

    Scolaro, A. F.

    1984-01-01

    Two basic findings were presented in the outlined report. The first is that silicon has a very high potential efficiency, demonstrated improvement in reliability and a significant potential for cost reductions. The second is that the photovoltaic technology development process is highly uncertain, but crystalline silicon technology has a substantial knowledge base to draw from, improving its chances of success. Several issues to be addressed are outlined.

  7. Crack growth in single-crystal silicon

    NASA Technical Reports Server (NTRS)

    Chen, C. P.; Leipold, M. H.

    1986-01-01

    Crack growth in single-crystal silicon at room temperature in air was evaluated by double torsion (DT) load-relaxation method and monitored by acoustic emission (AE) technique. Both DT and AE methods indicated lack of subcritical crack growth in silicon. At the critical stress intensity factor, the crack front was found to be jumping several times in a 'mirror' region and then followed by fast crack growth in a 'hackle' region. Hackle marks were found to be associated with plastic deformation at the tip of the fast moving crack. No dislocation etch pits were found in the 'mirror' region, in which crack growth may result from interatomic bonds broken at the crack tip under stress without any plastic deformation. Acoustic emission appears to be spontaneously generated from both interatomic bonds broken and dislocation generation at the moving crack tip during the crack growth in single-crystal silicon.

  8. A single crystalline porphyrinic titanium metal–organic framework

    SciTech Connect

    Yuan, Shuai; Liu, Tian -Fu; Feng, Dawei; Tian, Jian; Wang, Kecheng; Qin, Junsheng; Zhang, Qiang; Chen, Ying -Pin; Bosch, Mathieu; Zou, Lanfang; Teat, Simon J.; Dalgarno, Scott J.; Zhou, Hong -Cai

    2015-04-28

    We successfully assembled the photocatalytic titanium-oxo cluster and photosensitizing porphyrinic linker into a metal–organic framework (MOF), namely PCN-22. A preformed titanium-oxo carboxylate cluster is adopted as the starting material to judiciously control the MOF growth process to afford single crystals. This synthetic method is useful to obtain highly crystalline titanium MOFs, which has been a daunting challenge in this field. Moreover, PCN-22 demonstrated permanent porosity and photocatalytic activities toward alcohol oxidation.

  9. Freestanding single-crystalline magnetic structures fabricated by ion bombardment

    NASA Astrophysics Data System (ADS)

    Schoenherr, P.; Bischof, A.; Boehm, B.; Eib, P.; Grimm, S.; Alvarado, S. F.; Gross, L.; Allenspach, R.

    2015-01-01

    Starting from an ultrathin Fe film grown epitaxially on top of a GaAs(001) substrate, we show that freestanding structures can be created by ion-beam treatment. These structures are single-crystalline blisters and only a few nanometers thick. Anisotropic stress in the rim of a blister induces magnetic domain states magnetized in the direction normal to the blister edge. Experimental evidence is provided that the lateral size can be confined by starting from a nanostructured template.

  10. Freestanding single-crystalline magnetic structures fabricated by ion bombardment

    SciTech Connect

    Schoenherr, P.; Bischof, A.; Boehm, B.; Eib, P.; Grimm, S.; Gross, L.; Allenspach, R.; Alvarado, S. F.

    2015-01-19

    Starting from an ultrathin Fe film grown epitaxially on top of a GaAs(001) substrate, we show that freestanding structures can be created by ion-beam treatment. These structures are single-crystalline blisters and only a few nanometers thick. Anisotropic stress in the rim of a blister induces magnetic domain states magnetized in the direction normal to the blister edge. Experimental evidence is provided that the lateral size can be confined by starting from a nanostructured template.

  11. Growth of one-dimensional single-crystalline hydroxyapatite nanorods

    NASA Astrophysics Data System (ADS)

    Ren, Fuzeng; Ding, Yonghui; Ge, Xiang; Lu, Xiong; Wang, Kefeng; Leng, Yang

    2012-06-01

    A facile, effective and template/surfactant-free hydrothermal route in the presence of sodium bicarbonate was developed to synthesize highly uniform single-crystalline hydroxyapatite (HA) nanorods with the lengths of several hundred nanometers and aspect ratio up to ˜20. One dimensional (1-D) growth and aspect ratio could be controlled by hydrothermal reaction time and temperature. The longitudinal axis, also the growth direction of the nanorods, is parallel to the [001] direction of HA hexagonal crystal structure.

  12. Synthesis and characterization of single crystalline selenium nanowire arrays

    SciTech Connect

    Zhang, X.Y. . E-mail: apzhxy@polyu.edu.hk; Xu, L.H.; Dai, J.Y.; Cai, Y.; Wang, N.

    2006-09-14

    Ordered selenium nanowire arrays with diameters about 40 nm have been fabricated by electrodeposition using anodic porous alumina templates. As determined by X-ray diffraction, Raman spectra, electron diffraction and high-resolution transmission electron microscopy, selenium nanowires have uniform diameters, which are fully controllable. Single crystalline trigonal selenium nanowires have been obtained after postannealing at 180 deg. C. These nanowires are perfect with a c-axis growth orientation. The optical absorption spectra reveal two types of electron transition activity.

  13. Epitaxial single crystalline ferrite films for high frequency applications

    SciTech Connect

    Suzuki, Y.; Dover, R.B. van; Korenivski, V.; Werder, D.; Chen, C.H.; Felder, R.J.; Phillips, J.M.

    1996-11-01

    The successful growth of single crystal ferrites in thin film form is an important step towards their future incorporation into integrated circuits operating at microwave frequencies. The authors have successfully grown high quality single crystalline spinel ferrite thin films of (Mn,Zn)Fe{sub 2}O{sub 4} and CoFe{sub 2}O{sub 4} on (100) and (110) SrTiO{sub 3} and MgAl{sub 2}O{sub 4} at low temperature. These ferrite films are buffered with spinel structure layers that are paramagnetic at room temperature. In contrast to ferrite films grown directly on the substrates, ferrite films grown on buffered substrates exhibit excellent crystallinity and bulk saturation magnetization values, thus indicating the importance of lattice match and structural similarity between the film and the immediately underlying layer. X-ray, RBS, AFM and TEM analysis provide a consistent picture of the structural properties of these ferrite films. The authors then use this technique to grow exchange-coupled bilayers of single crystalline CoFe{sub 2}O{sub 4} and (Mn,Zn)Fe{sub 2}O{sub 4}. In these bilayers, they observe strong exchange coupling across the interface that is similar in strength to the exchange coupling in the individual layers.

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

    PubMed

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

    2015-04-01

    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. PMID:25758163

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

    SciTech Connect

    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.

  16. 77 FR 35425 - Crystalline Silicon Photovoltaic Cells and Modules From China; Scheduling of the Final Phase of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... 7, 2011. See 76 FR 61937 (Oct. 6, 2011) and the newly revised Commission's Handbook on E-Filing... 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,...

  17. High-Performance TiO2 -Based Electron-Selective Contacts for Crystalline Silicon Solar Cells.

    PubMed

    Yang, Xinbo; Bi, Qunyu; Ali, Haider; Davis, Kristopher; Schoenfeld, Winston V; Weber, Klaus

    2016-07-01

    Thin TiO2 films are demonstrated to be an excellent electron-selective contact for crystalline silicon solar cells. An efficiency of 21.6% is achieved for crystalline silicon solar cells featuring a full-area TiO2 -based electron-selective contact. PMID:27159874

  18. Single Shot Measurement of a Silicon Single Electron Transistor

    NASA Astrophysics Data System (ADS)

    Ferrus, T.; Hasko, D. G.; Morrissey, Q. R.; Burge, S. R.; Freeman, E. J.; French, M. J.; Lam, A.; Creswell, L.; Collier, R. J.; Williams, D. A.; Briggs, G. A. D.

    2009-06-01

    We describe measurements on a silicon single electron transistor (SET) carried out using a custom cryogenic CMOS measurement circuit (LTCMOS) in close proximity to the device. Quantum mechanical states in the SET were mapped by continuous microwave spectroscopy. The real time evolution of a particularly long lived quantum mechanical state was observed in a single shot measurement, made possible by the much faster measurement rate (50kHz bandwidth). This technique is intended to be applied to the measurement of coherent states in a charge qubit device made of a silicon double dot.

  19. Si + ion beam mixing of tin layers on crystalline silicon

    NASA Astrophysics Data System (ADS)

    Massouras, G.; Roger, J. A.; Romana, L.; Fuchs, G.

    1989-02-01

    Sn layers 64 nm thick deposited onto crystalline Si were irradiated at room temperature using 100 keV Si + ions, with fluences φ ranging from 1 × 10 15 to 9 × 10 16 ions cm -2. RBS analyses show that Si atoms move from the bulk towards the surface as the fluence increases, and are found at the very surface for φ = 4 × 10 16 Si + cm -2. Then a saturation is reached. Sn and Si profiles determined using a Fortran programme, and the calibration of depth scale is obtained from cross-sectional TEM observations. The average composition of the intermixed layer is given as a function of φ. Different layers of various crystallinity are found below the surface and their nature is discussed.

  20. 77 FR 73018 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-07

    ... FR 63791 (October 17, 2012) (``Final Determination''). \\2\\ See Crystalline Silicon Photovoltaic Cells... and Affirmative Preliminary Determination of Critical Circumstances,77 FR 31309 (May 25, 2012...., Ltd HC Solar Power Co., Ltd. 24.48 Zhiheng Solar Inc....... 24.48 Zhejiang Leye 24.48...

  1. 77 FR 25400 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-30

    ..., 76 FR 70966 (November 16, 2011), and Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's Republic of China: Initiation of Antidumping Duty Investigation, 76 FR..., 77 FR 17439 (March 26, 2012). Because the AD and CVD investigations were initiated simultaneously...

  2. 76 FR 81914 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-29

    ... Countervailing Duty Investigation, 76 FR 70966 (November 16, 2011). Postponement of Due Date for the Preliminary... Amended, 70 FR 24533 (May 10, 2005). This notice is issued and published pursuant to section 703(c)(2) of... International Trade Administration Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into...

  3. 77 FR 10478 - Crystalline Silicon Photovoltaic Cells, Whether or Not Assembled Into Modules, From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-22

    ... the Countervailing Duty Investigation, 76 FR 81914 (December 29, 2011). \\2\\ See Crystalline Silicon... Postponement of Preliminary Determination in the Countervailing Duty Investigation, 77 FR 4764 (January 31... Determination Deadlines Pursuant to the Tariff Act of 1930, As Amended, 70 FR 24533 (May 10, 2005). This...

  4. Planar-integrated single-crystalline perovskite photodetectors

    PubMed Central

    Saidaminov, Makhsud I.; Adinolfi, Valerio; Comin, Riccardo; Abdelhady, Ahmed L.; Peng, Wei; Dursun, Ibrahim; Yuan, Mingjian; Hoogland, Sjoerd; Sargent, Edward H.; Bakr, Osman M.

    2015-01-01

    Hybrid perovskites are promising semiconductors for optoelectronic applications. However, they suffer from morphological disorder that limits their optoelectronic properties and, ultimately, device performance. Recently, perovskite single crystals have been shown to overcome this problem and exhibit impressive improvements: low trap density, low intrinsic carrier concentration, high mobility, and long diffusion length that outperform perovskite-based thin films. These characteristics make the material ideal for realizing photodetection that is simultaneously fast and sensitive; unfortunately, these macroscopic single crystals cannot be grown on a planar substrate, curtailing their potential for optoelectronic integration. Here we produce large-area planar-integrated films made up of large perovskite single crystals. These crystalline films exhibit mobility and diffusion length comparable with those of single crystals. Using this technique, we produced a high-performance light detector showing high gain (above 104 electrons per photon) and high gain-bandwidth product (above 108 Hz) relative to other perovskite-based optical sensors. PMID:26548941

  5. Use of low energy hydrogen ion implants in high efficiency crystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.; Singh, R.

    1985-01-01

    This program is a study of the use of low energy hydrogen ion implantation for high efficiency crystalline silicon solar cells. The first quarterly report focuses on two tasks of this program: (1) an examination of the effects of low energy hydrogen implants on surface recombination speed; and (2) an examination of the effects of hydrogen on silicon regrowth and diffusion in silicon. The first part of the project focussed on the measurement of surface properties of hydrogen implanted silicon. Low energy hydrogen ions when bombarded on the silicon surface will create structural damage at the surface, deactivate dopants and introduce recombination centers. At the same time the electrically active centers such as dangling bonds will be passivated by these hydrogen ions. Thus hydrogen is expected to alter properties such as the surface recombination velocity, dopant profiles on the emitter, etc. In this report the surface recombination velocity of a hydrogen emplanted emitter was measured.

  6. Exposure to Fibres, Crystalline Silica, Silicon Carbide and Sulphur Dioxide in the Norwegian Silicon Carbide Industry

    PubMed Central

    Føreland, S.; Bye, E.; Bakke, B.; Eduard, W.

    2008-01-01

    Objectives: The aim of this study was to assess personal exposure to fibres, crystalline silica, silicon carbide (SiC) and sulphur dioxide in the Norwegian SiC industry. Methods: Approximately 720 fibre samples, 720 respirable dust samples and 1400 total dust samples were collected from randomly chosen workers from the furnace, processing and maintenance departments in all three Norwegian SiC plants. The respirable dust samples were analysed for quartz, cristobalite and non-fibrous SiC content. Approximately 240 sulphur dioxide samples were collected from workers in the furnace department. Results: The sorting operators from all plants, control room and cleaning operators in Plant A and charger, charger/mix and payloader operators in Plant C had a geometric mean (GM) of fibre exposure above the Norwegian occupational exposure limit (OEL) (0.1 fibre cm−3). The cleaner operators in Plant A had the highest GM exposure to respirable quartz (20 μg m−3). The charger/mix operators in Plant C had the highest GM exposure to respirable cristobalite (38 μg m−3) and the refinery crusher operators in Plant A had the highest GM exposure to non-fibrous SiC (0.65 mg m−3). Exposure to the crystalline silica and non-fibrous SiC was generally low and between 0.4 and 2.1% of the measurements exceeded the OELs. The cleaner operators in Plant A had the highest GM exposure to respirable dust (1.3 mg m−3) and total dust (21 mg m−3). GM exposures for respirable dust above the Norwegian SiC industry-specific OEL of 0.5 mg m−3 were also found for refinery crusher operators in all plants and mix, charger, charger/mix and sorting operators in Plant C. Only 4% of the total dust measurements exceeded the OEL for nuisance dust of (10 mg m−3). Exposure to sulphur dioxide was generally low. However, peaks in the range of 10–100 p.p.m. were observed for control room and crane operators in Plants A and B and for charger and charger/mix operators in Plant C. Conclusion: Workers in

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

    PubMed

    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

    2015-09-01

    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). PMID:26264738

  8. Laser induced lifetime degradation in p-type crystalline silicon

    SciTech Connect

    Ametowobla, M.; Bilger, G.; Koehler, J. R.; Werner, J. H.

    2012-06-01

    Pulsed, green laser irradiation of uncoated p-type silicon leads to a significant reduction of the effective minority carrier lifetime. The reason for the lifetime drop lies in the introduction of recombination centres into the laser melted and recrystallized surface layer, leading to a low local minority carrier lifetime {tau} Almost-Equal-To 10 ns inside this surface layer. The laser treatment introduces the impurities oxygen, carbon and nitrogen into the silicon and further leads to an n-type doping of the surface layer. There are strong indications that these impurities are responsible for the observed n-type doping, as well as the lifetime reduction after irradiation. Both effects are removed by thermal annealing. An estimate shows that the low local lifetime does nevertheless not affect the performance of industrial or contacted selective solar cell emitter structures.

  9. Laser induced lifetime degradation in p-type crystalline silicon

    NASA Astrophysics Data System (ADS)

    Ametowobla, M.; Bilger, G.; Köhler, J. R.; Werner, J. H.

    2012-06-01

    Pulsed, green laser irradiation of uncoated p-type silicon leads to a significant reduction of the effective minority carrier lifetime. The reason for the lifetime drop lies in the introduction of recombination centres into the laser melted and recrystallized surface layer, leading to a low local minority carrier lifetime τ ≈ 10 ns inside this surface layer. The laser treatment introduces the impurities oxygen, carbon and nitrogen into the silicon and further leads to an n-type doping of the surface layer. There are strong indications that these impurities are responsible for the observed n-type doping, as well as the lifetime reduction after irradiation. Both effects are removed by thermal annealing. An estimate shows that the low local lifetime does nevertheless not affect the performance of industrial or contacted selective solar cell emitter structures.

  10. Al-O interactions in ion-implanted crystalline silicon

    NASA Astrophysics Data System (ADS)

    Galvagno, G.; La Ferla, A.; Spinella, C.; Priolo, F.; Raineri, V.; Torrisi, Lucio; Rimini, E.; Carnera, A.; Gasparotto, A.

    1994-08-01

    The formation and dissolution of Si-O-Al precipitates have been investigated in Czochralski silicon wafers implanted with 6 MeV Al ions and thermally processed. The data have been compared to the O precipitation in samples implanted with 6 MeV Si or P ions. The amount of precipitated O atoms is about one order of magnitude higher for Al than for Si or P implanted samples. Moreover, a strong gettering of the Al atoms by the silicon dioxide precipitates has been observed. The precipitate evolution has been studied for different annealing times and temperatures. The oxygen precipitation has been simulated by the classical theory of nucleation and growth, with the introduction of new factors that take into account the implant damage distribution, the agglomeration of point defects during the initial stages of the annealing and the oxygen outdiffusion from the sample surface.

  11. Simultaneous broadband light trapping and fill factor enhancement in crystalline silicon solar cells induced by Ag nanoparticles and nanoshells.

    PubMed

    Fahim, Narges F; Jia, Baohua; Shi, Zhengrong; Gu, Min

    2012-09-10

    Crystalline silicon solar cells are predominant and occupying more than 89% of the global solar photovoltaic market. Despite the boom of the innovative solar technologies, few can provide a low-cost radical solution to dramatically boost the efficiency of crystalline silicon solar cells, which has reached plateau in the past ten years. Here, we present a novel strategy to simultaneously achieve dramatic enhancement in the short-circuit current and the fill factor through the integration of Ag plasmonic nanoparticles and nanoshells on the antireflection coating and the screen-printed fingers of monocrystalline silicon solar cells, respectively, by a single step and scalable modified electroless displacement method. As a consequence, up to 35.2% enhancement in the energy conversion efficiency has been achieved due to the plasmonic broadband light trapping and the significant reduction in the series resistance. More importantly, this method can further increase the efficiency of the best performing textured solar cells from 18.3% to 19.2%, producing the highest efficiency cells exceeding the state-of-the-art efficiency of the standard screen-printed solar cells. The dual functions of the Ag nanostructures, reported for the first time here, present a clear contrast to the previous works, where plasmonic nanostructures were integrated into solar cells to achieve the short-circuit current enhancement predominately. Our method offers a facile, cost-effective and scalable pathway for metallic nanostructures to be used to dramatically boost the overall efficiency of the optically thick crystalline silicon solar cells. PMID:23037536

  12. The Effect of Metallic Coatings and Crystallinity on the Volume Expansion of Silicon during Electrochemical Lithiation and Delithiation

    SciTech Connect

    Mcdowell, Matthew T.; Woo Lee, Seok; Wang, Chong M.; Cui, Yi

    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 one sidewall, the NW bilayer structure bends due to length changes in the silicon during delithiation. 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.

  13. A single molecule study of cellulase hydrolysis of crystalline cellulose

    NASA Astrophysics Data System (ADS)

    Liu, Yu-San; Luo, Yonghua; Baker, John O.; Zeng, Yining; Himmel, Michael E.; Smith, Steve; Ding, Shi-You

    2010-02-01

    Cellobiohydrolase-I (CBH I), a processive exoglucanase secreted by Trichoderma reesei, is one of the key enzyme components in a commercial cellulase mixture currently used for processing biomass to biofuels. CBH I contains a family 7 glycoside hydrolase catalytic module, a family 1 carbohydrate-binding module (CBM), and a highlyglycosylated linker peptide. It has been proposed that the CBH I cellulase initiates the hydrolysis from the reducing end of one cellulose chain and successively cleaves alternate β-1,4-glycosidic bonds to release cellobiose as its principal end product. The role each module of CBH I plays in the processive hydrolysis of crystalline cellulose has yet to be convincingly elucidated. In this report, we use a single-molecule approach that combines optical (Total Internal Reflection Fluorescence microscopy, or TIRF-M) and non-optical (Atomic Force Microscopy, or AFM) imaging techniques to analyze the molecular motion of CBM tagged with green fluorescence protein (GFP), and to investigate the surface structure of crystalline cellulose and changes made in the structure by CBM and CBH I. The preliminary results have revealed a confined nanometer-scale movement of the TrCBM1-GFP bound to cellulose, and decreases in cellulose crystal size as well as increases in surface roughness during CBH I hydrolysis of crystalline cellulose.

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

    SciTech Connect

    Boccard, Mathieu; Holman, Zachary

    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

  15. Cutting fluid study for single crystal silicon

    SciTech Connect

    Chargin, D.

    1998-05-05

    An empirical study was conducted to evaluate cutting fluids for Single Point Diamond Turning (SPDT) of single crystal silicon. The pH of distilled waster was adjusted with various additives the examine the effect of pH on cutting operations. Fluids which seemed to promote ductile cutting appeared to increase tool wear as well, an undesirable tradeoff. High Ph sodium hydroxide solutions showed promise for further research, as they yielded the best combination of reduced tool wear and good surface finish in the ductile regime. Negative rake tools were verified to improve the surface finish, but the negative rake tools used in the experiments also showed much higher wear than conventional 0{degree} rake tools. Effects of crystallographic orientation on SPDT, such as star patterns of fracture damage forming near the center of the samples, were observed to decrease with lower feedrates. Silicon chips were observed and photographed, indicative of a ductile materials removal process.

  16. Advantages of gated silicon single photon detectors

    NASA Astrophysics Data System (ADS)

    Legré, Matthieu; Lunghi, Tommaso; Stucki, Damien; Zbinden, Hugo

    2013-05-01

    We present gated silicon single photon detectors based on two commercially available avalanche photodiodes (APDs) and one customised APD from ID Quantique SA. This customised APD is used in a commercially available device called id110. A brief comparison of the two commercial APDs is presented. Then, the charge persistence effect of all of those detectors that occurs just after a strong illumination is shown and discussed.

  17. Hydrogen structures in heavily hydrogenated crystalline and amorphous silicon

    SciTech Connect

    Jackson, W.G.; Franz, A.; Chabal, Y.; Weldon, M.K.; Jin, H.C.; Abelson, J.R.

    1998-12-31

    The hydrogen binding energy distribution and IR spectra of hydrogen platelets in c-Si have been measured and compared to H in other forms of silicon including hydrogenated polycrystalline and amorphous Si. The binding distribution for platelet containing samples, determined using H evolution, exhibits two peaks: a bulk peak at 1.8--1.9 eV below the transport barrier, and a second possibly surface related peak 1.8--1.9 eV below the surface evolution barrier. The bulk peak grows at 250 C and is consistent with calculated energies for platelet structures. The same two evolution peaks are found in hydrogenated polycrystalline Si and amorphous silicon. The IR spectra for heavily hydrogenated c-Si are dominated by the stretching modes at 2076 and 2128 cm{sup {minus}1}. Most surprisingly there appears to be a strong mode at 856 cm{sup {minus}1} which is associated with a deformation mode of SiH{sub 3}. Even more surprising, this SiH{sub 3} 856 cm{sup {minus}1} mode remains until 550 C indicating that the SiH{sub 3} containing structures are rather stable.

  18. Synthesis and Characterization of Crystalline Silicon Carbide Nanoribbons

    PubMed Central

    2010-01-01

    In this paper, a simple method to synthesize silicon carbide (SiC) nanoribbons is presented. Silicon powder and carbon black powder placed in a horizontal tube furnace were exposed to temperatures ranging from 1,250 to 1,500°C for 5–12 h in an argon atmosphere at atmospheric pressure. The resulting SiC nanoribbons were tens to hundreds of microns in length, a few microns in width and tens of nanometers in thickness. The nanoribbons were characterized with electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy, and were found to be hexagonal wurtzite–type SiC (2H-SiC) with a growth direction of . The influence of the synthesis conditions such as the reaction temperature, reaction duration and chamber pressure on the growth of the SiC nanomaterial was investigated. A vapor–solid reaction dominated nanoribbon growth mechanism was discussed. PMID:20676202

  19. Synthesis and Characterization of Crystalline Silicon Carbide Nanoribbons

    NASA Astrophysics Data System (ADS)

    Zhang, Huan; Ding, Weiqiang; He, Kai; Li, Ming

    2010-08-01

    In this paper, a simple method to synthesize silicon carbide (SiC) nanoribbons is presented. Silicon powder and carbon black powder placed in a horizontal tube furnace were exposed to temperatures ranging from 1,250 to 1,500°C for 5-12 h in an argon atmosphere at atmospheric pressure. The resulting SiC nanoribbons were tens to hundreds of microns in length, a few microns in width and tens of nanometers in thickness. The nanoribbons were characterized with electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy, and were found to be hexagonal wurtzite-type SiC (2H-SiC) with a growth direction of [10bar{1}0] . The influence of the synthesis conditions such as the reaction temperature, reaction duration and chamber pressure on the growth of the SiC nanomaterial was investigated. A vapor-solid reaction dominated nanoribbon growth mechanism was discussed.

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

    PubMed

    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. PMID:26787682

  1. Maskless implants of 20 keV Ga{sup +} in thin crystalline silicon on insulator

    SciTech Connect

    Mio, A. M.; D'Arrigo, G.; Rimini, E.; Spinella, C.; Milazzo, R. G.; Peto, L.; Nadzeyka, A.; Bauerdick, S.

    2013-01-28

    A nano-sized ion beam apparatus has been used as maskless lithography to implant 20 keV Ga{sup +} ions into a 26 nm thick silicon crystalline film on insulator. The ion beam, with about 5 nm standard deviation, delivered few hundred ions during a single shot. Circular areas with nominal diameter of 20 or 50 nm were irradiated to a fluence of 5 Multiplication-Sign 10{sup 14}/cm{sup 2}. Transmission electron microscopy evidenced that the damaged regions are characterized by an irregular contour with many disordered filaments. Damage extends across the layer thickness and fast Fourier transform analysis indicates that implantation causes the amorphization of a region which extends beyond the nominal diameter. In situ annealing experiments demonstrated that the disordered filamentary regions disappear in the 250-450 Degree-Sign C temperature range and the interfaces with the surrounding crystalline regions sharpen. A temperature as high as 600 Degree-Sign C is required to fully re-crystallize the amorphous core of the implanted dots. Reordering occurs by multi-orientation lateral solid-phase epitaxial growth and the breaking of (111) and (101) interfaces, due to the formation of twins, triggers a fast crystallization kinetics. Rapid thermal annealing (890 Degree-Sign C-10 s) completely crystallizes the amorphous regions, twins are absent and small cluster of defects remains instead. Preliminary scanning capacitance measurements indicate that the implanted atoms, after crystallization, are electrically active. The implant method is then a viable processing step for the doping of non-bulk fully depleted ultra-thin-body MOSFET.

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

    PubMed Central

    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

  3. Vibrational Lifetime of Interstitial Oxygen in Crystalline Silicon

    NASA Astrophysics Data System (ADS)

    Sun, Baozhou; Fraser, Andrew; Lüpke, Gunter

    2003-03-01

    - The lifetime of the asymmetric stretch mode of interstitial oxygen in crystalline Si is measured directly by transient bleaching spectroscopy. The 1136-cm-1 mode has an extremely long lifetime, T1 = 229 ps at 10 K. The lifetime shows surprisingly strong temperature dependence, decreasing by more than two orders in magnitude between 50 and 180 K. The dominating decay channel involves a high number of low-frequency modes of 142 +/- 20 cm-1 corresponding to transverse acoustic phonons or pseudolocalized modes of Oi. This work was supported in part by NSF through grant DMR-00-76027, ONR through grant N00014-01-1-0770, and the Thomas F. and Kate Miller Jeffress Memorial Trust through grant J-545.

  4. Epitaxial growth of homogeneous single-crystalline AlN films on single-crystalline Cu (1 1 1) substrates

    NASA Astrophysics Data System (ADS)

    Wang, Wenliang; Yang, Weijia; Liu, Zuolian; Lin, Yunhao; Zhou, Shizhong; Qian, Huirong; Gao, Fangliang; Yang, Hui; Li, Guoqiang

    2014-03-01

    The homogeneous and crack free single-crystalline AlN thin films have been epitaxially grown on single-crystalline Cu (1 1 1) substrates with an in-plane alignment of AlN [11-20]//Cu [1-10] by pulsed laser deposition (PLD) technology with an integrated laser rastering program. The as-grown AlN films are studied by spectroscopic ellipsometry, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), polarized light microscopy, high-resolution X-ray diffraction, and high-resolution transmission electron microscopy (HRTEM). The spectroscopic ellipsometry reveals the excellent thickness uniformity of as-grown AlN films on the Cu (1 1 1) substrates with a root-mean-square (RMS) thickness inhomogeneity less than 2.6%. AFM and FESEM measurements indicate that very smooth and flat surface AlN films are obtained with a surface RMS roughness of 2.3 nm. The X-ray reflectivity image illustrates that there is a maximum of 1.2 nm thick interfacial layer existing between the as-grown AlN and Cu (1 1 1) substrates and is confirmed by HRTEM measurement, and reciprocal space mapping shows that almost fully relaxed AlN films are achieved only with a compressive strain of 0.48% within ˜321 nm thick films. This work demonstrates a possibility to obtain homogeneous and crack free single-crystalline AlN films on metallic substrates by PLD with optimized laser rastering program, and brings up a broad prospect for the application of acoustic filters that require abrupt hetero-interfaces between the AlN films and the metallic electrodes.

  5. Variations in Crystalline Structures and Electrical Properties of Single Crystalline Boron Nitride Nanosheets.

    PubMed

    Aldalbahi, Ali; Zhou, Andrew Feng; Feng, Peter

    2015-01-01

    We report the studies of (1) the basic mechanism underlying the formation of defect-free, single crystalline boron nitride nanosheets (BNNSs) synthesized using pulsed laser plasma deposition (PLPD) technique, (2) the variation in the crystalline structure at the edges of the hexagonal boron nitride (h-BN) nanosheets, and (3) the basic electrical properties related to the BNNSs tunneling effect and electrical breakdown voltage. The nanoscale morphologies of BNNSs are characterized using scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM). The results show that each sample consisted of a number of transparent BNNSs that partially overlapped one another. Varying the deposition duration yielded different thicknesses of sample but did not affect the morphology, structure, and thickness of individual BNNSs pieces. Analysis of the SEM and HRTEM data revealed changes in the spatial period of the B3-N3 hexagonal structures and the interlayer distance at the edge of the BNNSs, which occurred due to the limited number of atomic layers and was confirmed further by x-ray diffraction (XRD) study. The experimental results clearly indicate that the values of the electrical conductivities of the super-thin BNNSs and the effect of temperature relied strongly on the direction of observation. PMID:26563901

  6. Variations in Crystalline Structures and Electrical Properties of Single Crystalline Boron Nitride Nanosheets

    PubMed Central

    Aldalbahi, Ali; Zhou, Andrew Feng; Feng, Peter

    2015-01-01

    We report the studies of (1) the basic mechanism underlying the formation of defect-free, single crystalline boron nitride nanosheets (BNNSs) synthesized using pulsed laser plasma deposition (PLPD) technique, (2) the variation in the crystalline structure at the edges of the hexagonal boron nitride (h-BN) nanosheets, and (3) the basic electrical properties related to the BNNSs tunneling effect and electrical breakdown voltage. The nanoscale morphologies of BNNSs are characterized using scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM). The results show that each sample consisted of a number of transparent BNNSs that partially overlapped one another. Varying the deposition duration yielded different thicknesses of sample but did not affect the morphology, structure, and thickness of individual BNNSs pieces. Analysis of the SEM and HRTEM data revealed changes in the spatial period of the B3–N3 hexagonal structures and the interlayer distance at the edge of the BNNSs, which occurred due to the limited number of atomic layers and was confirmed further by x-ray diffraction (XRD) study. The experimental results clearly indicate that the values of the electrical conductivities of the super-thin BNNSs and the effect of temperature relied strongly on the direction of observation. PMID:26563901

  7. Stable porous crystalline silicon with nanotubular structure: A predicted allotrope with direct band gap

    NASA Astrophysics Data System (ADS)

    Tang, Chi-Pui; Cao, Jie; Xiong, Shi-Jie

    2015-06-01

    On basis of the first principle calculation we show that a crystalline structure of silicon, as a novel allotrope with nanotubular holes along two perpendicular directions, is stable. The calculations on geometrical and electronic properties reveal that this allotrope possesses a direct band gap wider by 0.5 eV than the indirect one of silicon with diamond structure. The crystal belongs to I41/AMD space group, showing anisotropic optical properties and Young modulus. The bulk modulus is 64.4 GPa and the density is 1.9 g/cm3, lower than that of the diamond silicon due to the presence of nanotubular holes. It is hopeful that the allotrope may widely expand applications of silicon in many fields due to its direct band gap and specific nanotubular structure.

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

    SciTech Connect

    Gee, J.M.; Gordon, R.; Liang, H.

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. On the generation of grooves on crystalline silicon irradiated by femtosecond laser pulses.

    PubMed

    He, Shutong; Nivas, Jijil J J; Vecchione, Antonio; Hu, Minglie; Amoruso, Salvatore

    2016-02-22

    Irradiation of crystalline silicon with femtosecond laser pulses produces a variety of quasi-periodic surface structures, among which sub-wavelength ripples creation is largely studied. Here we report an experimental investigation and a theoretical interpretation focusing on the seldom considered issue of quasi-periodic, micron spaced grooves formation. We characterize the morphological evolution of the grooves generation and experimentally single out the variation of the threshold fluence for their formation with the number of pulses N, while typical ripples simultaneously produced in the irradiated area are always considered for comparison. Our experimental findings evidence a power law dependence of the threshold fluence on the number of pulses both for ripples and grooves formation, typical of an incubation behavior. The incubation factor and single pulse threshold are (0.76 ± 0.04) and (0.20 ± 0.04) J/cm2 for ripples and (0.84 ± 0.03) and (0.54 ± 0.08) J/cm2 for grooves, respectively. Surface-scattered wave theory, which allows modeling irradiation with a single pulse on a rough surface, is exploited to interpret the observed structural modification of the surface textures. A simple, empirical scaling approach is proposed associating the surface structures generated in multiple-pulse experiments with the predictions of the surface-scattered wave theory, at laser fluencies around the grooves formation threshold. This, in turn, allows proposing a physical mechanism interpreting the grooves generation as well as the coexistence and relative prominence of grooves and ripples in the irradiated area. PMID:26906987

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

    PubMed

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

    2015-09-01

    In this study, various silicon dielectric films, namely, a-SiOx:H, a-SiNx:H, and a-SiOxNy:H, grown by plasma enhanced chemical vapor deposition (PECVD) were evaluated for use as interlayers (ILs) between crystalline silicon and glass. Chemical bonding analysis using Fourier transform infrared spectroscopy showed that high values of oxidant gases (CO2 and/or N2), added to SiH4 during PECVD, reduced the Si-H and N-H bond density in the silicon dielectrics. Various three layer stacks combining the silicon dielectric materials were designed to minimize optical losses between silicon and glass in rear side contacted heterojunction pn test cells. The PECVD grown silicon dielectrics retained their functionality despite being subjected to harsh subsequent processing such as crystallization of the silicon at 1414 °C or above. High values of short circuit current density (Jsc; without additional hydrogen passivation) required a high density of Si-H bonds and for the nitrogen containing films, additionally, a high N-H bond density. Concurrently high values of both Jsc and open circuit voltage Voc were only observed when [Si-H] was equal to or exceeded [N-H]. Generally, Voc correlated with a high density of [Si-H] bonds in the silicon dielectric; otherwise, additional hydrogen passivation using an active plasma process was required. The highest Voc ∼ 560 mV, for a silicon acceptor concentration of about 10(16) cm(-3), was observed for stacks where an a-SiOxNy:H film was adjacent to the silicon. Regardless of the cell absorber thickness, field effect passivation of the buried silicon surface by the silicon dielectric was mandatory for efficient collection of carriers generated from short wavelength light (in the vicinity of the glass-Si interface). However, additional hydrogen passivation was obligatory for an increased diffusion length of the photogenerated carriers and thus Jsc in solar cells with thicker absorbers. PMID:26281016

  12. Solution-Based Synthesis of Crystalline Silicon from Liquid Silane through Laser and Chemical Annealing

    SciTech Connect

    Iyer, Ganjigunte R. S.; Hobbie, Erik K.; Guruvenket, Srinivasan; Hoey, Justin M.; Anderson, Kenneth J.; Lovaasen, John; Gette, Cody; Schulz, Douglas L.; Swenson, Orven F.; Elangovan, Arumugasamy; Boudjouk, P.

    2012-05-23

    We report a solution process for the synthesis of crystalline silicon from the liquid silane precursor cyclohexasilane (Si6H12). Polysilane films were crystallized through thermal and laser annealing, with plasma hydrogenation at atmospheric pressure generating further structural changes in the films. The evolution from amorphous to microcrystalline is characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and impedance spectroscopy. A four-decade enhancement in the electrical conductivity is attributed to a disorder-order transition in a bonded Si network. Lastly, our results demonstrate a potentially attractive approach that employs a solution process coupled with ambient post-processing to produce crystalline silicon thin films.

  13. Planar-integrated single-crystalline perovskite photodetectors.

    PubMed

    Saidaminov, Makhsud I; Adinolfi, Valerio; Comin, Riccardo; Abdelhady, Ahmed L; Peng, Wei; Dursun, Ibrahim; Yuan, Mingjian; Hoogland, Sjoerd; Sargent, Edward H; Bakr, Osman M

    2015-01-01

    Hybrid perovskites are promising semiconductors for optoelectronic applications. However, they suffer from morphological disorder that limits their optoelectronic properties and, ultimately, device performance. Recently, perovskite single crystals have been shown to overcome this problem and exhibit impressive improvements: low trap density, low intrinsic carrier concentration, high mobility, and long diffusion length that outperform perovskite-based thin films. These characteristics make the material ideal for realizing photodetection that is simultaneously fast and sensitive; unfortunately, these macroscopic single crystals cannot be grown on a planar substrate, curtailing their potential for optoelectronic integration. Here we produce large-area planar-integrated films made up of large perovskite single crystals. These crystalline films exhibit mobility and diffusion length comparable with those of single crystals. Using this technique, we produced a high-performance light detector showing high gain (above 10(4) electrons per photon) and high gain-bandwidth product (above 10(8) Hz) relative to other perovskite-based optical sensors. PMID:26548941

  14. Method for forming single phase, single crystalline 2122 BCSCO superconductor thin films by liquid phase epitaxy

    NASA Technical Reports Server (NTRS)

    Pandey, Raghvendra K. (Inventor); Raina, Kanwal (Inventor); Solayappan, Narayanan (Inventor)

    1994-01-01

    A substantially single phase, single crystalline, highly epitaxial film of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8 superconductor which has a T.sub.c (zero resistance) of 83 K is provided on a lattice-matched substrate with no intergrowth. This film is produced by a Liquid Phase Epitaxy method which includes the steps of forming a dilute supercooled molten solution of a single phase superconducting mixture of oxides of Bi, Ca, Sr, and Cu having an atomic ratio of about 2:1:2:2 in a nonreactive flux such as KCl, introducing the substrate, e.g., NdGaO.sub.3, into the molten solution at 850.degree. C., cooling the solution from 850.degree. C. to 830.degree. C. to grow the film and rapidly cooling the substrate to room temperature to maintain the desired single phase, single crystalline film structure.

  15. Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry.

    PubMed

    Huang, Jer-Shing; Callegari, Victor; Geisler, Peter; Brüning, Christoph; Kern, Johannes; Prangsma, Jord C; Wu, Xiaofei; Feichtner, Thorsten; Ziegler, Johannes; Weinmann, Pia; Kamp, Martin; Forchel, Alfred; Biagioni, Paolo; Sennhauser, Urs; Hecht, Bert

    2010-01-01

    Deep subwavelength integration of high-definition plasmonic nanostructures is of key importance in the development of future optical nanocircuitry for high-speed communication, quantum computation and lab-on-a-chip applications. To date, the experimental realization of proposed extended plasmonic networks consisting of multiple functional elements remains challenging, mainly because of the multi-crystallinity of commonly used thermally evaporated gold layers. This can produce structural imperfections in individual circuit elements that drastically reduce the yield of functional integrated nanocircuits. In this paper we demonstrate the use of large (>100 μm(2)) but thin (<80 nm) chemically grown single-crystalline gold flakes that, after immobilization, serve as an ideal basis for focused ion beam milling and other top-down nanofabrication techniques on any desired substrate. Using this methodology we obtain high-definition ultrasmooth gold nanostructures with superior optical properties and reproducible nano-sized features over micrometre-length scales. Our approach provides a possible solution to overcome the current fabrication bottleneck and realize high-definition plasmonic nanocircuitry. PMID:21267000

  16. Microdefects and self-interstitial diffusion in crystalline silicon

    SciTech Connect

    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.

  17. Studies of the nature of interfacial barriers in high efficiency crystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Bates, Clayton W., Jr.

    1985-01-01

    The effects of interfacial barriers in crystalline silicon solar cells were studied. The effort was directed toward the investigation and use of such techniques as Angular Resolved Parameter Spectroscopy (ARAPS) and Impedance Spectroscopy in initially characterizing n-type Si doped to levels commonly used for n+p solar cells, and eventually Si solar cells. The objectives of the research are given. Those accomplished are detailed, as are recommendations for future work.

  18. 17th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Workshop Proceedings

    SciTech Connect

    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.'

  19. Phase transformation as the single-mode mechanical deformation of silicon

    SciTech Connect

    Wong, S. Williams, J. S.; Bradby, J. E.; Haberl, B.

    2015-06-22

    The metastable body-centered cubic (bc8) and rhombohedral (r8) phases of silicon that are formed after the nanoindentation of diamond cubic silicon exhibit properties that are of both scientific and technological interest. This letter demonstrates that large regions of these phases can be readily formed from crystalline silicon via nanoindentation with minimal damage to the surrounding crystal. Cross-sectional transmission electron microscopy is used to show that volumes of these phases 6 μm wide and up to 650 nm deep can be generated using a symmetrical spherical tip of ∼21.5 μm diameter. This result indicates that the use of large symmetrical spherical tips result in highly hydrostatic conditions that can favor the single phase transformation mode without extensive damage to the surrounding crystalline regions that are observed in previous studies.

  20. Nanophotonics-based low-temperature PECVD epitaxial crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Chen, Wanghua; Cariou, Romain; Foldyna, Martin; Depauw, Valerie; Trompoukis, Christos; Drouard, Emmanuel; Lalouat, Loic; Harouri, Abdelmounaim; Liu, Jia; Fave, Alain; Orobtchouk, Régis; Mandorlo, Fabien; Seassal, Christian; Massiot, Inès; Dmitriev, Alexandre; Lee, Ki-Dong; Cabarrocas, Pere Roca i.

    2016-03-01

    The enhancement of light absorption via nanopatterning in crystalline silicon solar cells is becoming extremely important with the decrease of wafer thickness for the further reduction of solar cell fabrication cost. In order to study the influence of nanopatterning on crystalline silicon thin-film solar cells, we applied two lithography techniques (laser interference lithography and nanoimprint lithography) combined with two etching techniques (dry and wet) to epitaxial crystalline silicon thin films deposited via plasma-enhanced chemical vapor deposition at 175 °C. The influence of nanopatterning with different etching profiles on solar cell performance is studied. We found that the etching profiles (pitch, depth and diameter) have a stronger impact on the passivation quality (open circuit voltage and fill factor) than on the optical performance (short circuit current density) of the solar cells. We also show that nanopatterns obtained via wet-etching can improve solar cell performance; and in contrast, dry-etching leads to poor passivation related to the etching profile, surface damage, and/or contamination introduced during the etching process.

  1. Periodic magnetic domains in single-crystalline cobalt filament arrays

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Wang, Fan; Jia, Fei; Li, Jingning; Liu, Kai; Huang, Sunxiang; Luan, Zhongzhi; Wu, Di; Chen, Yanbin; Zhu, Jianmin; Peng, Ru-Wen; Wang, Mu

    2016-02-01

    Magnetic structures with controlled domain wall pattern may be applied as potential building blocks for three-dimensional magnetic memory and logic devices. Using a unique electrochemical self-assembly method, we achieve regular single-crystalline cobalt filament arrays with specific geometric profile and crystallographic orientation, and the magnetic domain configuration can be conveniently tailored. We report the transition of periodic antiparallel magnetic domains to compressed vortex magnetic domains depending on the ratio of height to width of the wires. A "phase diagram" is obtained to describe the dependence of the type of magnetic domain and the geometrical profiles of the wires. Magnetoresistance of the filaments demonstrates that the contribution of a series of 180∘ domain walls is over 0.15 % of the zero-field resistance ρ (H =0 ) . These self-assembled magnetic nanofilaments, with controlled periodic domain patterns, offer an interesting platform to explore domain-wall-based memory and logic devices.

  2. Fatigue crack propagation behavior of a single crystalline superalloy

    NASA Technical Reports Server (NTRS)

    Lerch, B. A.; Antolovich, Stephen D.

    1990-01-01

    Crack propagation mechanisms occurring at various temperatures in a single crystalline Ni-base alloy, Rene N4, were investigated. The rates of crack growth at 21, 704, 927, 1038, and 1093 C were measured in specimens with 001-line and 110-line directions parallel to the load axis and the machined notch, respectively, using a pulsed dc potential drop apparatus, and the fracture surfaces at each temperature were examined using SEM. Crack growth rates (CGRs) for specimens tested at or below 927 C were similar, while at two higher temperatures, the CGRs were about an order of magnitude higher than at the lower temperatures. Results of SEM observations showed that surface morphologies depended on temperature.

  3. Physical properties of single crystalline BaSn{sub 5}

    SciTech Connect

    Lin, Xiao; Budko, Sergey; Canfield, Paul

    2012-01-30

    We present a comprehensive study of the binary intermetallic superconductor, BaSn{sub 5}. High-quality single crystalline BaSn{sub 5} was grown out of a Sn flux. Detailed thermodynamic and transport measurements were performed to study BaSn{sub 5}'s normal and superconducting state properties. This material appears to be a strongly coupled, multiband superconductor. H{sub c2}(T) is almost isotropic. De Haas–van Alphen oscillations were observed and two effective masses were estimated from the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ≈−0.053 ± 0.001 K/kbar.

  4. Optical and electrical properties of single-crystalline zirconium carbide

    SciTech Connect

    Modine, F.A.; Haywood, T.W.; Allison, C.Y.

    1985-12-15

    Optical and electrical properties are reported for single-crystalline ZrC/sub 0.89/. The specular reflectance was measured between 0.025 and 6.5 eV, and ellipsometry measurements were made between 1.2 and 4.5 eV. The combination of ellipsometry with reflectance allows optical functions to be computed reliably between 0 and 6.5 eV and also provides a check on the consistency of the measurements. The van der Pauw technique was used to measure the electrical resistivity of the samples at temperatures between 4.2 and 300 K and the Hall coefficient at room temperature. Drude parameters obtained from the electrical measurements are in good agreement with those obtained from the optical data. Both the optical and electrical results are compared to other experimental results and to theory.

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

    PubMed

    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. PMID:27199344

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

    NASA Astrophysics Data System (ADS)

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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 cm2 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.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 cm2 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. Electronic supplementary information (ESI) available: Modelling (Fig. S1) and

  8. Determining the crystalline degree of silicon nanoclusters/SiO{sub 2} multilayers by Raman scattering

    SciTech Connect

    Hernández, S.; López-Vidrier, J.; López-Conesa, L.; Peiró, F.; Garrido, B.; Hiller, D.; Gutsch, S.; Zacharias, M.; Ibáñez, J.

    2014-05-28

    We use Raman scattering to investigate the size distribution, built-in strains and the crystalline degree of Si-nanoclusters (Si-nc) in high-quality Si-rich oxynitride/SiO{sub 2} multilayered samples obtained by plasma enhanced chemical vapor deposition and subsequent annealing at 1150 °C. An initial structural characterization of the samples was performed by means of energy-filtered transmission electron microscopy (EFTEM) and X-ray diffraction (XRD) to obtain information about the cluster size and the presence of significant amounts of crystalline phase. The contributions to the Raman spectra from crystalline and amorphous Si were analyzed by using a phonon confinement model that includes the Si-nc size distribution, the influence of the matrix compressive stress on the clusters, and the presence of amorphous Si domains. Our lineshape analysis confirms the existence of silicon precipitates in crystalline state, in good agreement with XRD results, and provides also information about the presence of a large compressive stress over the Si-nc induced by the SiO{sub 2} matrix. By using the Raman spectra from low temperature annealed samples (i.e., before the crystallization of the Si-nc), the relative scattering cross-section between crystalline and amorphous Si was evaluated as a function of the crystalline Si size. Taking into account this parameter and the integrated intensities for each phase as extracted from the Raman spectra, we were able to evaluate the degree of crystallization of the precipitated Si-nc. Our data suggest that all samples exhibit high crystalline fractions, with values up to 89% for the biggest Si-nc. The Raman study, supported by the EFTEM characterization, indicates that this system undergoes a practically abrupt phase separation, in which the precipitated Si-nanoclusters are formed by a crystalline inner part surrounded by a thin amorphous shell of approximately 1–2 atomic layers.

  9. Single-layer crystalline phases of antimony: Antimonenes

    NASA Astrophysics Data System (ADS)

    Aktürk, O. Üzengi; Ã-zçelik, V. Ongun; Ciraci, S.

    2015-06-01

    The pseudolayered character of 3D bulk crystals of antimony has led us to predict its 2D single-layer crystalline phase named antimonene in a buckled honeycomb structure like silicene. Sb atoms also form an asymmetric washboard structure like black phospherene. Based on an extensive analysis comprising ab initio phonon and finite-temperature molecular dynamics calculations, we show that these two single-layer phases are robust and can remain stable at high temperatures. They are nonmagnetic semiconductors with band gaps ranging from 0.3 eV to 1.5 eV, and are suitable for 2D electronic applications. The washboard antimonene displays strongly directional mechanical properties, which may give rise to a strong influence of strain on the electronic properties. Single-layer antimonene phases form bilayer and trilayer structures with wide interlayer spacings. In multilayers, this spacing is reduced and eventually the structure changes to 3D pseudolayered bulk crystals. The zigzag and armchair nanoribbons of the antimonene phases have fundamental band gaps derived from reconstructed edge states and display a diversity of magnetic and electronic properties depending on their width and edge geometry. Their band gaps are tunable with the widths of the nanoribbons. When grown on substrates, such as germanene or Ge(111), the buckled antimonene attains a significant influence of substrates.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  11. High energy picosecond laser for applications in microstructuring of crystalline silicon

    NASA Astrophysics Data System (ADS)

    Lin, Xuechun; Yu, Haijuan; Huang, Yongguang; Zhang, Ling; Zhu, Hongliang

    2012-10-01

    Black silicon is very promising for the third generation Solar Cells, because of its fascinating light absorption of above 98% in visible spectrum and more than 90% in 800-2500 nm, and its surface micro-nano structures enlarge light trapping intermediate impurities levels caused by supersaturated doping expand absorptive limitation of crystalline Si. In recent years femtosecond laser pulses were widely used in the process of improving the absorptance by irradiating silicon surfaces with in the presence of different gases. Nevertheless, picosecond laser used to fabricate large-area black silicon is seldom reported. A diode-pumped picosecond Nd:YAG regenerative amplifier laser system designed for microstructuring the crystalline silicon was reported in this paper. At the repetition of 1 kHz, the system generated 1 W average-power, 26-ps-long pulses with a pulse energy of 1 mJ at 1064 nm, which corresponds the peak power of 38.5 MW. A 0.5 W second-harmonic 532 nm laser is achieved with a 20 mm long noncritically phase-matched lithium triborate (LBO) crystal from the 1W 1064 nm laser. igh optical absorption black Si irradiated with 1064 nm and 532 nm picosecond pulses in SF6 at different laser fluence. And the relationship between the surface morphology and the wavelength or the laser fluence was researched.

  12. Impact of dislocations and dangling bond defects on the electrical performance of crystalline silicon thin films

    SciTech Connect

    Steffens, S.; Becker, C. Amkreutz, D.; Schnegg, A.; Abou-Ras, D.; Lips, K.; Rech, B.; Klossek, A.; Kittler, M.; Chen, Y.-Y.; Klingsporn, M.

    2014-07-14

    A wide variety of liquid and solid phase crystallized silicon films are investigated in order to determine the performance limiting defect types in crystalline silicon thin-film solar cells. Complementary characterization methods, such as electron spin resonance, photoluminescence, and electron microscopy, yield the densities of dangling bond defects and dislocations which are correlated with the electronic material quality in terms of solar cell open circuit voltage. The results indicate that the strongly differing performance of small-grained solid and large-grain liquid phase crystallized silicon can be explained by intra-grain defects like dislocations rather than grain boundary dangling bonds. A numerical model is developed containing both defect types, dislocations and dangling bonds, describing the experimental results.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    DOEpatents

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

    1999-01-01

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

  15. Fiber Optic Excitation of Silicon Microspheres in Amorphous and Crystalline Fluids

    NASA Astrophysics Data System (ADS)

    Yılmaz, Huzeyfe; Yılmaz, Hasan; Sharif Murib, Mohammed; Serpengüzel, Ali

    2016-03-01

    This study investigates the optical resonance spectra of free-standing monolithic single crystal silicon microspheres immersed in various amorphous fluids, such as air, water, ethylene glycol, and 4-Cyano-4'-pentylbiphenyl nematic liquid crystal. For the various amorphous fluids, morphology-dependent resonances with quality factors on the order of 105 are observed at 1428 nm. The mode spacing is always on the order of 0.23 nm. The immersion in various amorphous fluids affects the spectral response of the silicon microsphere and heralds this technique for use in novel optofluidics applications. Even though the nematic liquid crystal is a highly birefringent, scattering, and high-index optical medium, morphology-dependent resonances with quality factors on the order of 105 are observed at 1300 nm in the elastic scattering spectra of the silicon microsphere, realizing a liquid-crystal-on-silicon geometry. The relative refractive index and the size parameter of the silicon microsphere are the parameters that affect the resonance structure. The more 4-Cyano-4'-pentylbiphenyl interacting with the silicon microsphere, the lower the quality factor of the resonances is. The more 4-Cyano-4'-pentylbiphenyl is interacting with the silicon microsphere, the lower the mode spacing Δλ of the resonances is. The silicon microspheres wetted with nematic liquid crystal can be used for optically addressed liquid-crystal-on-silicon displays, light valve applications, or reconfigurable optical networks.

  16. Formation of quasi-single crystalline porous ZnO nanostructures with a single large cavity

    NASA Astrophysics Data System (ADS)

    Cho, Seungho; Kim, Semi; Jung, Dae-Won; Lee, Kun-Hong

    2011-09-01

    We report a method for synthesizing quasi-single crystalline porous ZnO nanostructures containing a single large cavity. The microwave-assisted route consists of a short (about 2 min) temperature ramping stage (from room temperature to 120 °C) and a stage in which the temperature is maintained at 120 °C for 2 h. The structures produced by this route were 200-480 nm in diameter. The morphological yields of this method were very high. The temperature- and time-dependent evolution of the synthesized powders and the effects of an additive, vitamin C, were studied. Spherical amorphous/polycrystalline structures (70-170 nm in diameter), which appeared transitorily, may play a key role in the formation of the single crystalline porous hollow ZnO nanostructures. Studies and characterization of the nanostructures suggested a possible mechanism for formation of the quasi-single crystalline porous ZnO nanostructures with an interior space.We report a method for synthesizing quasi-single crystalline porous ZnO nanostructures containing a single large cavity. The microwave-assisted route consists of a short (about 2 min) temperature ramping stage (from room temperature to 120 °C) and a stage in which the temperature is maintained at 120 °C for 2 h. The structures produced by this route were 200-480 nm in diameter. The morphological yields of this method were very high. The temperature- and time-dependent evolution of the synthesized powders and the effects of an additive, vitamin C, were studied. Spherical amorphous/polycrystalline structures (70-170 nm in diameter), which appeared transitorily, may play a key role in the formation of the single crystalline porous hollow ZnO nanostructures. Studies and characterization of the nanostructures suggested a possible mechanism for formation of the quasi-single crystalline porous ZnO nanostructures with an interior space. Electronic supplementary information (ESI) available: TEM images and the corresponding SAED image of a Zn

  17. Bright Single Photon Emitter in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Lienhard, Benjamin; Schroeder, Tim; Mouradian, Sara; Dolde, Florian; Trong Tran, Toan; Aharonovich, Igor; Englund, Dirk

    Efficient, on-demand, and robust single photon emitters are of central importance to many areas of quantum information processing. Over the past 10 years, color centers in solids have emerged as excellent single photon emitters. Color centers in diamond are among the most intensively studied single photon emitters, but recently silicon carbide (SiC) has also been demonstrated to be an excellent host material. In contrast to diamond, SiC is a technologically important material that is widely used in optoelectronics, high power electronics, and microelectromechanical systems. It is commercially available in sizes up to 6 inches and processes for device engineering are well developed. We report on a visible-spectrum single photon emitter in 4H-SiC. The emitter is photostable at both room and low temperatures, and it enables 2 million photons/second from unpatterned bulk SiC. We observe two classes of orthogonally polarized emitters, each of which has parallel absorption and emission dipole orientations. Low temperature measurements reveal a narrow zero phonon line with linewidth < 0.1 nm that accounts for more than 30% of the total photoluminescence spectrum. To our knowledge, this SiC color emitter is the brightest stable room-temperature single photon emitter ever observed.

  18. Deformation mechanisms in nanoscale single crystalline electroplated copper pillars

    NASA Astrophysics Data System (ADS)

    Jennings, Andrew T.

    Scientific research in nanotechnology has enabled advances in a diverse range of applications, such as: electronics, chemical sensing, and cancer treatment. In order to transition these nanotechnology-driven innovations out of the laboratory and into real-world applications, the resilience and mechanical reliability of nanoscale structures must be well understood in order to preserve functionality under real-world operating environments. Understanding the mechanical properties of nanoscale materials is especially important because several authors have shown that single crystalline metal pillars produced through focused-ion-beam milling have unique properties when the pillar diameter, D, approaches nanotechnology-relevant dimensions. The strength, sigma, of these pillars is size-dependent and is well described through a power-law relation showing that smaller is stronger: sigma∝D-n , where n is the exponent and is found to be 0.5≤n≤1.0 in face-centered-cubic metals. In this work, the fundamental deformation mechanisms governing the size-dependent mechanical properties are investigated through uniaxial compression and tension tests of electroplated single crystalline copper pillars with diameters between 75 nm and 1000 nm. At larger pillar diameters, D >125 nm, these copper pillars are shown to obey a similar size-dependent regime, demonstrating that the "smaller is stronger" phenomenon is a function of the pillar microstructure, as opposed to the fabrication route. Furthermore, the dominant dislocation mechanism in this size-dependent regime is shown to be the result of single-arm, or spiral, sources. At smaller pillar diameters, D≤125 nm, a strain-rate-dependent mechanism transition is observed through both the size-strength relation and also quantitative, experimental measures of the activation volume. This new deformation regime is characterized by a size-independent strength and is governed by surface dislocation nucleation, a thermally activated

  19. Combined single-crystalline and polycrystalline CVD diamond substrates for diamond electronics

    SciTech Connect

    Vikharev, A. L. Gorbachev, A. M.; Dukhnovsky, M. P.; Muchnikov, A. B.; Ratnikova, A. K.; Fedorov, Yu. Yu.

    2012-02-15

    The fabrication of diamond substrates in which single-crystalline and polycrystalline CVD diamond form a single wafer, and the epitaxial growth of diamond films on such combined substrates containing polycrystalline and (100) single-crystalline CVD diamond regions are studied.

  20. Novel Approach for Selective Emitter Formation and Front Side Metallization of Crystalline Silicon Solar Cells

    SciTech Connect

    Xu, Baomin

    2010-07-26

    In this project we will explore the possibility of forming the front side metallization and selective emitter layer for the crystalline silicon solar cells through using selective laser ablation to create contact openings on the front surface and a screen printer to make connections with conductive paste. Using this novel approach we expect to reduce the specific contact resistance of the silver gridlines by about one order of magnitude compared to the state-of-art industrial crystalline silicon solar cells to below 1 mΩ∙cm2, and use lightly doped n+ emitter layer with sheet resistance of not smaller than 100 Ω. This represents an enabling improvement on crystalline silicon solar cell performance and can increase the absolute efficiency of the solar cell by about 1%. In this scientific report we first present our result on the selective laser ablation of the nitride layer to make contact openings. Then we report our work on the solar cell fabrication by using the laser ablated contact openings with self-doping paste. Through various electrical property characterization and SIMS analysis, the factors limiting the cell performance have been discussed. While through this proof-of-concept project we could not reach the target on cell efficiency improvement, the process to fabricate 125mm full-sized silicon solar cells using laser ablation and self-doping paste has been developed, and a much better understanding of technical challenges has been achieved. Future direction to realize the potential of the new technology has been clearly defined.

  1. Influence of the surface termination on the light emission of crystalline silicon nanoparticles.

    PubMed

    Botas, Alexandre M P; Anthony, Rebecca J; Wu, Jeslin; Rowe, David J; Silva, Nuno J O; Kortshagen, Uwe; Pereira, Rui N; Ferreira, Rute A S

    2016-08-12

    The light emission properties of silicon crystalline nanoparticles (SiNPs) have been investigated using steady-state and time-resolved photoluminescence measurements carried out at 12 K and at room temperature. To enable a comparative study of the role of surface terminal groups on the optical properties, we investigated SiNPs-H ensembles with the same mean NP diameter but differing on the surface termination, namely organic-functionalized with 1-dodecene (SiNPs-C12) and H-terminated (SiNPs-H). We show that although the spectral dependence of the light emission is rather unaffected by surface termination, characterized by a single broad band peaking at ∼1.64 eV, both the exciton recombination lifetimes and quantum yields display a pronounced dependence on the surface termination. Exciton lifetimes and quantum yields are found to be significantly lower in SiNPs-H compared SiNPs-C12. This difference is due to distinct non-radiative recombination probabilities resulting from inter-NP exciton migration, which in SiNPs-C12 is inhibited by the energy barriers imposed by the bulky surface groups. The surface groups of organic-terminated SiPs are responsible for the inhibition of inter-NP exciton transfer, yielding a higher quantum yield compared to SiNPs-H. The surface oxidation of SiNPs-C12 leads to the appearance of a phenomenon of an exciton transference from to the Si core to oxide-related states that contribute to light emission. These excitons recombine radiatively, explaining why the emission quantum of the organic-terminated SiNPs is the same after surface oxidation of SiNPs-C12. PMID:27348305

  2. Electrical characterization of 6H crystalline silicon carbide. M.S. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Lempner, Stephen E.

    1994-01-01

    Crystalline silicon carbide (SiC) substrates and epilayers, undoped as well as n- and p-doped, have been electrically characterized by performing Hall effect and resistivity measurements (van der Pauw) over the temperature range of approximately 85 K to 650 K (200 K to 500 K for p-type sample). By fitting the measured temperature dependent carrier concentration data to the single activation energy theoretical model: (1) the activation energy for the nitrogen donor ranged from 0.078 eV to 0.101 eV for a doping concentration range of 10(exp 17) cm(exp -3) to 10(exp 18) cm(exp -3) and (2) the activation energy for the aluminum acceptor was 0.252 eV for a doping concentration of 4.6 x 10(exp 18) cm(exp -3). By fitting the measured temperature dependent carrier concentration data to the double activation energy level theoretical model for the nitrogen donor: (1) the activation energy for the hexagonal site was 0.056 eV and 0.093 eV corresponding to doping concentrations of 3.33 x 10 (exp 17) cm(exp -3) and 1.6 x 10(exp 18) cm(exp -3) and (2) the activation energy for the cubic site was 0.113 and 0.126 eV corresponding to doping concentrations of 4.2 x 10(exp 17) cm(exp -3) and 5.4 x 10(exp 18) cm(exp -3).

  3. Influence of the surface termination on the light emission of crystalline silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Botas, Alexandre M. P.; Anthony, Rebecca J.; Wu, Jeslin; Rowe, David J.; Silva, Nuno J. O.; Kortshagen, Uwe; Pereira, Rui N.; Ferreira, Rute A. S.

    2016-08-01

    The light emission properties of silicon crystalline nanoparticles (SiNPs) have been investigated using steady-state and time-resolved photoluminescence measurements carried out at 12 K and at room temperature. To enable a comparative study of the role of surface terminal groups on the optical properties, we investigated SiNPs-H ensembles with the same mean NP diameter but differing on the surface termination, namely organic-functionalized with 1-dodecene (SiNPs-C12) and H-terminated (SiNPs-H). We show that although the spectral dependence of the light emission is rather unaffected by surface termination, characterized by a single broad band peaking at ∼1.64 eV, both the exciton recombination lifetimes and quantum yields display a pronounced dependence on the surface termination. Exciton lifetimes and quantum yields are found to be significantly lower in SiNPs-H compared SiNPs-C12. This difference is due to distinct non-radiative recombination probabilities resulting from inter-NP exciton migration, which in SiNPs-C12 is inhibited by the energy barriers imposed by the bulky surface groups. The surface groups of organic-terminated SiPs are responsible for the inhibition of inter-NP exciton transfer, yielding a higher quantum yield compared to SiNPs-H. The surface oxidation of SiNPs-C12 leads to the appearance of a phenomenon of an exciton transference from to the Si core to oxide-related states that contribute to light emission. These excitons recombine radiatively, explaining why the emission quantum of the organic-terminated SiNPs is the same after surface oxidation of SiNPs-C12.

  4. 14th Workshop on Crystalline Silicon Solar Cells& Modules: Materials and Processes; Summary of Discussion Sessions

    SciTech Connect

    Sopori, B.; Tan, T.; Sinton, R.; Swanson, D.

    2004-10-01

    The 14th Workshop discussion sessions addressed funding needs for Si research and for R&D to enhance U.S. PV manufacturing. The wrap-up session specifically addressed topics for the new university silicon program. The theme of the workshop, Crystalline Silicon Solar Cells: Leapfrogging the Barriers, was selected to reflect the astounding progress in Si PV technology during last three decades, despite a host of barriers and bottlenecks. A combination of oral, poster, and discussion sessions addressed recent advances in crystal growth technology, new cell structures and doping methods, silicon feedstock issues, hydrogen passivation and fire through metallization, and module issues/reliability. The following oral/discussion sessions were conducted: (1) Technology Update; (2) Defects and Impurities in Si/Discussion; (3) Rump Session; (4) Module Issues and Reliability/Discussion; (5) Silicon Feedstock/Discussion; (6) Novel Doping, Cells, and Hetero-Structure Designs/Discussion; (7) Metallization/Silicon Nitride Processing/Discussion; (8) Hydrogen Passivation/Discussion; (9) Characterization/Discussion; and (10) Wrap-Up. This year's workshop lasted three and a half days and, for the first time, included a session on Si modules. A rump session was held on the evening of August 8, which addressed efficiency expectations and challenges of c Si solar cells/modules. Richard King of DOE and Daren Dance of Wright Williams& Kelly (formerly of Sematech) spoke at two of the luncheon sessions. Eleven students received Graduate Student Awards from funds contributed by the PV industry.

  5. Orientation-dependent mechanical behavior and phase transformation of mono-crystalline silicon

    NASA Astrophysics Data System (ADS)

    Sun, Jiapeng; Ma, Aibin; Jiang, Jinghua; Han, Jing; Han, Ying

    2016-03-01

    We perform a large-scale molecular dynamics simulation of nanoindentation on the (100), (110), and (111) oriented silicon surface to investigate the orientation-dependent mechanical behavior and phase transformation of monocrystalline silicon. The results show both the remarkable anisotropic mechanical behavior and structure phase transformation of monocrystalline silicon. The mechanical behavior of the (110) and (111) oriented surfaces are similar (has a high indentation modulus, low critical indentation depth for the onset of plastic deformation) but quite different from the (100) oriented surface. The mechanical behavior is carefully linked to the phase transformation. The formation of crystalline bct5 phase and β-Si phase is the fundamental phase transformation mechanism for (100) oriented surface. But, a large number of amorphous silicon can be found beneath the indenter for (110) and (111) oriented surface beside the bct5 phase and β-Si phase. The β-Si phase region is relatively small for (110) and (111) oriented surface, even cannot be detected for (111) oriented surface. This result highlights the dominating role of the amorphous transformation in the mechanical behavior of monocrystalline silicon. Additionally, our results indicate that the high pressure phases form a symmetrical, anisotropic pattern on the indented surface for all three oriented surface which is linked to the active {111}<110> slip systems.

  6. Single-charge transport in ambipolar silicon nanoscale field-effect transistors

    SciTech Connect

    Mueller, Filipp; Konstantaras, Georgios; Wiel, Wilfred G. van der; Zwanenburg, Floris A.

    2015-04-27

    We report single-charge transport in ambipolar nanoscale MOSFETs, electrostatically defined in near-intrinsic silicon. We use the ambipolarity to demonstrate the confinement of either a few electrons or a few holes in exactly the same crystalline environment underneath a gate electrode. We find similar electron and hole quantum dot properties while the mobilities differ quantitatively like in microscale devices. The understanding and control of individual electrons and holes are essential for spin-based quantum information processing.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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. PMID:26785682

  9. First Principles Simulations of the Electrochemical Lithiation and Delithiation of Faceted Crystalline Silicon

    SciTech Connect

    Chan, Maria K.; Wolverton, Christopher M.; Greeley, Jeffrey P.

    2012-09-05

    Silicon is of significant interest as a next-generation anode material for lithium-ion batteries due to its extremely high capacity. The reaction of lithium with crystalline silicon is known to present a rich range of phenomena, including electrochemical solid state amorphization, crystallization at full lithiation of a Li15Si4 phase, hysteresis in the first lithiation–delithiation cycle, and highly anisotropic lithiation in crystalline samples. Very little is known about these processes at an atomistic level, however. To provide fundamental insights into these issues, we develop and apply a first principles, history-dependent, lithium insertion and removal algorithm to model the process of lithiation and subsequent delithiation of crystalline Si. The simulations give a realistic atomistic picture of lithiation demonstrating, for the first time, the amorphization process and hinting at the formation of the Li15Si4 phase. Voltages obtained from the simulations show that lithiation of the (110) surface is thermodynamically more favorable than lithiation of the (100) or (111) surfaces, providing an explanation for the drastic lithiation anisotropy seen in experiments on Si micro- and nanostructures. Analysis of the delithiation and relithiation processes also provides insights into the underlying physics of the lithiation–delithiation hysteresis, thus providing firm conceptual foundations for future design of improved Si-based anodes for Li ion battery applications.

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

    PubMed

    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 × 10(6) and 3.72 × 10(6) 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. PMID:26785682

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Fabrication of single crystalline, uniaxial single domain Co nanowire arrays with high coercivity

    NASA Astrophysics Data System (ADS)

    Ramazani, A.; Almasi Kashi, M.; Montazer, A. H.

    2014-03-01

    Whilst Co nanorods with high coercivity were synthesized during recent years, they did not achieve the same results as for Co nanowires embedded in solid templates. In the present work, Co nanowire arrays (NWAs) with high coercivity were successfully fabricated in porous aluminum oxide template under optimum conditions by using pulsed ac electrodeposition technique. Magnetic properties and crystalline characteristics of the nanowires were investigated by hysteresis loop measurements, first-order reversal curve (FORC) analysis, X-ray diffraction (XRD), and selected area electron diffraction (SAED) patterns. Hysteresis loop measurements showed high coercivity of about 4.8 kOe at room temperature together with optimum squareness of 1, resulting in an increase of the previous maximum coercivity for Co NWAs up to 45%. XRD and SAED patterns revealed a single crystalline texture along the [0002] direction, indicating the large magnetocrystalline anisotropy. On the other hand, FORC analysis confirmed a single domain structure for the Co NWAs. In addition, the reversal mechanism of the single crystalline, single domain Co NWAs was studied which resulted in the fixed easy axis with a coherent rotation. Accordingly, these nanowires might offer promising applications in high density bit patterned media and low power logic devices.

  14. Fabrication of single crystalline, uniaxial single domain Co nanowire arrays with high coercivity

    SciTech Connect

    Ramazani, A. Almasi Kashi, M.; Montazer, A. H.

    2014-03-21

    Whilst Co nanorods with high coercivity were synthesized during recent years, they did not achieve the same results as for Co nanowires embedded in solid templates. In the present work, Co nanowire arrays (NWAs) with high coercivity were successfully fabricated in porous aluminum oxide template under optimum conditions by using pulsed ac electrodeposition technique. Magnetic properties and crystalline characteristics of the nanowires were investigated by hysteresis loop measurements, first-order reversal curve (FORC) analysis, X-ray diffraction (XRD), and selected area electron diffraction (SAED) patterns. Hysteresis loop measurements showed high coercivity of about 4.8 kOe at room temperature together with optimum squareness of 1, resulting in an increase of the previous maximum coercivity for Co NWAs up to 45%. XRD and SAED patterns revealed a single crystalline texture along the [0002] direction, indicating the large magnetocrystalline anisotropy. On the other hand, FORC analysis confirmed a single domain structure for the Co NWAs. In addition, the reversal mechanism of the single crystalline, single domain Co NWAs was studied which resulted in the fixed easy axis with a coherent rotation. Accordingly, these nanowires might offer promising applications in high density bit patterned media and low power logic devices.

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

    NASA Astrophysics Data System (ADS)

    Cui, Jie; Grant, Nicholas; Lennon, Alison

    2014-12-01

    Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO2) was investigated. The anodic SiO2 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 SiO2 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 × 1011 cm-2 and a moderate density of interface states of 6 × 1011 eV-1 cm-2. This corresponded to a silicon surface recombination velocity of 62 cm s-1, which is comparable with values reported for other anodic SiO2 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 × 10-10 and 1.6 × 10-9 A cm-2 at 1 and -1 V, respectively, was measured for LIA SiO2 suggesting its potential application as insulation layer in IBC solar cells and a barrier for potential induced degradation.

  16. Single-crystalline aluminum film for ultraviolet plasmonic nanolasers

    NASA Astrophysics Data System (ADS)

    Chou, Bo-Tsun; Chou, Yu-Hsun; Wu, Yen-Mo; Chung, Yi-Cheng; Hsueh, Wei-Jen; Lin, Shih-Wei; Lu, Tien-Chang; Lin, Tzy-Rong; Lin, Sheng-Di

    2016-01-01

    Significant advances have been made in the development of plasmonic devices in the past decade. Plasmonic nanolasers, which display interesting properties, have come to play an important role in biomedicine, chemical sensors, information technology, and optical integrated circuits. However, nanoscale plasmonic devices, particularly those operating in the ultraviolet regime, are extremely sensitive to the metal and interface quality. Thus, these factors have a significant bearing on the development of ultraviolet plasmonic devices. Here, by addressing these material-related issues, we demonstrate a low-threshold, high-characteristic-temperature metal-oxide-semiconductor ZnO nanolaser that operates at room temperature. The template for the ZnO nanowires consists of a flat single-crystalline Al film grown by molecular beam epitaxy and an ultrasmooth Al2O3 spacer layer synthesized by atomic layer deposition. By effectively reducing the surface plasmon scattering and metal intrinsic absorption losses, the high-quality metal film and the sharp interfaces formed between the layers boost the device performance. This work should pave the way for the use of ultraviolet plasmonic nanolasers and related devices in a wider range of applications.

  17. Single-crystalline aluminum film for ultraviolet plasmonic nanolasers.

    PubMed

    Chou, Bo-Tsun; Chou, Yu-Hsun; Wu, Yen-Mo; Chung, Yi-Cheng; Hsueh, Wei-Jen; Lin, Shih-Wei; Lu, Tien-Chang; Lin, Tzy-Rong; Lin, Sheng-Di

    2016-01-01

    Significant advances have been made in the development of plasmonic devices in the past decade. Plasmonic nanolasers, which display interesting properties, have come to play an important role in biomedicine, chemical sensors, information technology, and optical integrated circuits. However, nanoscale plasmonic devices, particularly those operating in the ultraviolet regime, are extremely sensitive to the metal and interface quality. Thus, these factors have a significant bearing on the development of ultraviolet plasmonic devices. Here, by addressing these material-related issues, we demonstrate a low-threshold, high-characteristic-temperature metal-oxide-semiconductor ZnO nanolaser that operates at room temperature. The template for the ZnO nanowires consists of a flat single-crystalline Al film grown by molecular beam epitaxy and an ultrasmooth Al2O3 spacer layer synthesized by atomic layer deposition. By effectively reducing the surface plasmon scattering and metal intrinsic absorption losses, the high-quality metal film and the sharp interfaces formed between the layers boost the device performance. This work should pave the way for the use of ultraviolet plasmonic nanolasers and related devices in a wider range of applications. PMID:26814581

  18. Single-crystalline aluminum film for ultraviolet plasmonic nanolasers

    PubMed Central

    Chou, Bo-Tsun; Chou, Yu-Hsun; Wu, Yen-Mo; Chung, Yi-Cheng; Hsueh, Wei-Jen; Lin, Shih-Wei; Lu, Tien-Chang; Lin, Tzy-Rong; Lin, Sheng-Di

    2016-01-01

    Significant advances have been made in the development of plasmonic devices in the past decade. Plasmonic nanolasers, which display interesting properties, have come to play an important role in biomedicine, chemical sensors, information technology, and optical integrated circuits. However, nanoscale plasmonic devices, particularly those operating in the ultraviolet regime, are extremely sensitive to the metal and interface quality. Thus, these factors have a significant bearing on the development of ultraviolet plasmonic devices. Here, by addressing these material-related issues, we demonstrate a low-threshold, high-characteristic-temperature metal-oxide-semiconductor ZnO nanolaser that operates at room temperature. The template for the ZnO nanowires consists of a flat single-crystalline Al film grown by molecular beam epitaxy and an ultrasmooth Al2O3 spacer layer synthesized by atomic layer deposition. By effectively reducing the surface plasmon scattering and metal intrinsic absorption losses, the high-quality metal film and the sharp interfaces formed between the layers boost the device performance. This work should pave the way for the use of ultraviolet plasmonic nanolasers and related devices in a wider range of applications. PMID:26814581

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Vertically Integrated MEMS SOI Composite Porous Silicon-Crystalline Silicon Cantilever-Array Sensors: Concept for Continuous Sensing of Explosives and Warfare Agents

    NASA Astrophysics Data System (ADS)

    Stolyarova, Sara; Shemesh, Ariel; Aharon, Oren; Cohen, Omer; Gal, Lior; Eichen, Yoav; Nemirovsky, Yael

    This study focuses on arrays of cantilevers made of crystalline silicon (c-Si), using SOI wafers as the starting material and using bulk micromachining. The arrays are subsequently transformed into composite porous silicon-crystalline silicon cantilevers, using a unique vapor phase process tailored for providing a thin surface layer of porous silicon on one side only. This results in asymmetric cantilever arrays, with one side providing nano-structured porous large surface, which can be further coated with polymers, thus providing additional sensing capabilities and enhanced sensing. The c-Si cantilevers are vertically integrated with a bottom silicon die with electrodes allowing electrostatic actuation. Flip Chip bonding is used for the vertical integration. The readout is provided by a sensitive Capacitance to Digital Converter. The fabrication, processing and characterization results are reported. The reported study is aimed towards achieving miniature cantilever chips with integrated readout for sensing explosives and chemical warfare agents in the field.

  1. Surface finish in ultra-precision diamond turning of single-crystal silicon

    NASA Astrophysics Data System (ADS)

    Ayomoh, M.; Abou-El-Hossein, K.

    2015-10-01

    Silicon is an optical material widely used in the production of infrared optics. However, silicon as a brittle material exhibits some difficulties when ultra-precision machined by mono-crystalline single point diamond. Finish turning of silicon with mono- crystalline diamond inserts results in accelerated tool wear rates if the right combination of the machining parameters is not properly selected. In this study, we conducted a series of machining tests on an ultra-high precision machine tool using finish turning conditions when using mono-crystalline diamond inserts with negative rake angle and relatively big nose radius. The study yields some recommendations on the best combination of machining parameters that will result in maximum material removal rates with smallest possible surface finish. In this work, standard non-controlled waviness diamond inserts having nose radius of about 1.5 mm, rake angle of negative 25°, and clearance angle of 5° were used to produce flat surfaces on silicon disk. From the results, it has been established that feed rate has the most influential effect followed by the depth of cut and cutting speed.

  2. Computation modelling on von Mises stress in multi-crystalline silicon ingot for PV application

    NASA Astrophysics Data System (ADS)

    Aravindan, G.; Srinivasan, M.; Aravinth, K.; Ramasamy, P.

    2016-05-01

    Numerical simulation studies have been made on multi crystalline-Silicon (mc-Si) growth by directional solidification (DS) process for Photovoltaic (PV) application. Heat transfer plays an important role in the DS process as dislocation density and growth rate are controlled by temperature gradient of the DS furnace. The heat transfer in the DS furnace is controlled by movement of side wall insulation at different velocity upto 200 mm from the bottom insulation. The simulation results show that the thermal stress in the mc-si ingot for 0.2 mm/min velocity is minimum.

  3. Formation kinetics of copper-related light-induced degradation in crystalline silicon

    SciTech Connect

    Lindroos, J. Savin, H.

    2014-12-21

    Light-induced degradation (LID) is a deleterious effect in crystalline silicon, which is considered to originate from recombination-active boron-oxygen complexes and/or copper-related defects. Although LID in both cases appears as a fast initial decay followed by a second slower degradation, we show that the time constant of copper-related degradation increases with increasing boron concentration in contrast to boron-oxygen LID. Temperature-dependent analysis reveals that the defect formation is limited by copper diffusion. Finally, interface defect density measurements confirm that copper-related LID is dominated by recombination in the wafer bulk.

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

    PubMed

    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. PMID:24751350

  5. Studying The Kinetics Of Crystalline Silicon Nanoparticle Lithiation With In-Situ Transmission Electron Microscopy

    SciTech Connect

    Mcdowell, Matthew T.; Ryu, Ill; Lee, Seokwoo; Wang, Chong M.; Nix, William D.; Cui, Yi

    2012-11-27

    Silicon is an attractive high-capacity anode material for Li-ion batteries, but a comprehensive understanding of the massive ~300% volume change and fracture during lithiation/delithiation is necessary to reliably employ Si anodes. Here, in-situ transmission electron microscopy (TEM) of the lithiation of crystalline Si nanoparticles reveals that the reaction slows down as it progresses into the particle interior. Analysis suggests that this behavior is due to the influence of mechanical stress at the reaction front on the driving force for the reaction. These experiments give insight into the factors controlling the kinetics of this unique reaction.

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

    SciTech Connect

    Nguyen, Hieu T. Macdonald, Daniel; Baker-Finch, Simeon C.

    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.

  7. Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

    DOEpatents

    Ownby, G.W.; White, C.W.; Zehner, D.M.

    1979-12-28

    This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an atomically clean region. This can be accomplished in a system at a pressure below 10-/sup 8/ Torr, using Q-switched ruber-laser pulses having an energy density in the range of from about 60 to 190 MW/cm/sup 2/.

  8. Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

    DOEpatents

    Ownby, Gary W.; White, Clark W.; Zehner, David M.

    1981-01-01

    This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an automatically clean region. This can be accomplished in a system at a pressure below 10.sup.-8 Torr, using Q-switched ruby-laser pulses having an energy density in the range of from about 60 to 190 MW/cm.sup.2.

  9. Solution-Based Synthesis of Crystalline Silicon from Liquid Silane through Laser and Chemical Annealing

    DOE PAGESBeta

    Iyer, Ganjigunte R. S.; Hobbie, Erik K.; Guruvenket, Srinivasan; Hoey, Justin M.; Anderson, Kenneth J.; Lovaasen, John; Gette, Cody; Schulz, Douglas L.; Swenson, Orven F.; Elangovan, Arumugasamy; et al

    2012-05-23

    We report a solution process for the synthesis of crystalline silicon from the liquid silane precursor cyclohexasilane (Si6H12). Polysilane films were crystallized through thermal and laser annealing, with plasma hydrogenation at atmospheric pressure generating further structural changes in the films. The evolution from amorphous to microcrystalline is characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and impedance spectroscopy. A four-decade enhancement in the electrical conductivity is attributed to a disorder-order transition in a bonded Si network. Lastly, our results demonstrate a potentially attractive approach that employs a solution process coupled with ambient post-processing to produce crystallinemore » silicon thin films.« less

  10. "Liquid Knife" to Fabricate Patterning Single-Crystalline Perovskite Microplates toward High-Performance Laser Arrays.

    PubMed

    Feng, Jiangang; Yan, Xiaoxu; Zhang, Yifan; Wang, Xuedong; Wu, Yuchen; Su, Bin; Fu, Hongbin; Jiang, Lei

    2016-05-01

    A facile and effective "liquid knife" is created by controlling the dewetting process of the liquid precursor, yielding patterning single-crystalline perovskite microplates with uniform size, precise positioning, high quality, and low lasing thresholds. The sizes and location of single-crystalline perovskite are controllable, leading to mode-tunable lasing emission and patterned lasers. PMID:27000628