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Sample records for primary silicon crystals

  1. Quasimetallic silicon micromachined photonic crystals

    International Nuclear Information System (INIS)

    Temelkuran, B.; Bayindir, Mehmet; Ozbay, E.; Kavanaugh, J. P.; Sigalas, M. M.; Tuttle, G.

    2001-01-01

    We report on fabrication of a layer-by-layer photonic crystal using highly doped silicon wafers processed by semiconductor micromachining techniques. The crystals, built using (100) silicon wafers, resulted in an upper stop band edge at 100 GHz. The transmission and defect characteristics of these structures were found to be analogous to metallic photonic crystals. We also investigated the effect of doping concentration on the defect characteristics. The experimental results agree well with predictions of the transfer matrix method simulations

  2. A continuous Czochralski silicon crystal growth system

    Science.gov (United States)

    Wang, C.; Zhang, H.; Wang, T. H.; Ciszek, T. F.

    2003-03-01

    Demand for large silicon wafers has driven the growth of silicon crystals from 200 to 300 mm in diameter. With the increasing silicon ingot sizes, melt volume has grown dramatically. Melt flow becomes more turbulent as melt height and volume increase. To suppress turbulent flow in a large silicon melt, a new Czochralski (CZ) growth furnace has been designed that has a shallow melt. In this new design, a crucible consists of a shallow growth compartment in the center and a deep feeding compartment around the periphery. Two compartments are connected with a narrow annular channel. A long crystal may be continuously grown by feeding silicon pellets into the dedicated feeding compartment. We use our numerical model to simulate temperature distribution and velocity field in a conventional 200-mm CZ crystal growth system and also in the new shallow crucible CZ system. By comparison, advantages and disadvantages of the proposed system are observed, operating conditions are determined, and the new system is improved.

  3. Nickel-induced crystallization of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, J A; Arce, R D; Buitrago, R H [INTEC (CONICET-UNL), Gueemes 3450, S3000GLN Santa Fe (Argentina); Budini, N; Rinaldi, P, E-mail: jschmidt@intec.unl.edu.a [FIQ - UNL, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina)

    2009-05-01

    The nickel-induced crystallization of hydrogenated amorphous silicon (a-Si:H) is used to obtain large grained polycrystalline silicon thin films on glass substrates. a-Si:H is deposited by plasma enhanced chemical vapour deposition at 200 deg. C, preparing intrinsic and slightly p-doped samples. Each sample was divided in several pieces, over which increasing Ni concentrations were sputtered. Two crystallization methods are compared, conventional furnace annealing (CFA) and rapid thermal annealing (RTA). The crystallization was followed by optical microscopy and scanning electron microscopy observations, X-ray diffraction, and reflectance measurements in the UV region. The large grain sizes obtained - larger than 100{mu}m for the samples crystallized by CFA - are very encouraging for the preparation of low-cost thin film polycrystalline silicon solar cells.

  4. Photonic Crystal Sensors Based on Porous Silicon

    Directory of Open Access Journals (Sweden)

    Claudia Pacholski

    2013-04-01

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

  5. Photonic Crystal Sensors Based on Porous Silicon

    Science.gov (United States)

    Pacholski, Claudia

    2013-01-01

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

  6. Intravitreal properties of porous silicon photonic crystals

    Science.gov (United States)

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

    2009-01-01

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

  7. Anisotropy of Single-Crystal Silicon in Nanometric Cutting.

    Science.gov (United States)

    Wang, Zhiguo; Chen, Jiaxuan; Wang, Guilian; Bai, Qingshun; Liang, Yingchun

    2017-12-01

    The anisotropy exhibited by single-crystal silicon in nanometric cutting is very significant. In order to profoundly understand the effect of crystal anisotropy on cutting behaviors, a large-scale molecular dynamics model was conducted to simulate the nanometric cutting of single-crystal silicon in the (100)[0-10], (100)[0-1-1], (110)[-110], (110)[00-1], (111)[-101], and (111)[-12-1] crystal directions in this study. The simulation results show the variations of different degrees in chip, subsurface damage, cutting force, and friction coefficient with changes in crystal plane and crystal direction. Shear deformation is the formation mechanism of subsurface damage, and the direction and complexity it forms are the primary causes that result in the anisotropy of subsurface damage. Structurally, chips could be classified into completely amorphous ones and incompletely amorphous ones containing a few crystallites. The formation mechanism of the former is high-pressure phase transformation, while the latter is obtained under the combined action of high-pressure phase transformation and cleavage. Based on an analysis of the material removal mode, it can be found that compared with the other crystal direction on the same crystal plane, the (100)[0-10], (110)[-110], and (111)[-101] directions are more suitable for ductile cutting.

  8. LYSO crystal calorimeter readout with silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Berra, A., E-mail: alessandro.berra@gmail.com [Università degli Studi dell' Insubria (Italy); INFN sezione di Milano Bicocca (Italy); Bonvicini, V. [INFN sezione di Trieste (Italy); Cecchi, C.; Germani, S. [INFN sezione di Perugia (Italy); Guffanti, D. [Università degli Studi dell' Insubria (Italy); Lietti, D. [Università degli Studi dell' Insubria (Italy); INFN sezione di Milano Bicocca (Italy); Lubrano, P.; Manoni, E. [INFN sezione di Perugia (Italy); Prest, M. [Università degli Studi dell' Insubria (Italy); INFN sezione di Milano Bicocca (Italy); Rossi, A. [INFN sezione di Perugia (Italy); Vallazza, E. [INFN sezione di Trieste (Italy)

    2014-11-01

    Large area Silicon PhotoMultipliers (SiPMs) are the new frontier of the development of readout systems for scintillating detectors. A SiPM consists of a matrix of parallel-connected silicon micropixels operating in limited Geiger–Muller avalanche mode, and thus working as independent photon counters with a very high gain (∼10{sup 6}). This contribution presents the performance in terms of linearity and energy resolution of an electromagnetic homogeneous calorimeter composed of 9∼18X{sub 0} LYSO crystals. The crystals were readout by 36 4×4 mm{sup 2} SiPMs (4 for each crystal) produced by FBK-irst. This calorimeter was tested at the Beam Test Facility at the INFN laboratories in Frascati with a single- and multi-particle electron beam in the 100–500 MeV energy range.

  9. Materials of construction for silicon crystal growth

    Science.gov (United States)

    Leipold, M. H.; Odonnell, T. P.; Hagan, M. A.

    1980-01-01

    The performance of materials for construction and in contact with molten silicon for crystal growth is presented. The basis for selection considers physical compatibility, such as thermal expansion and strength, as well as chemical compatibility as indicated by contamination of the silicon. A number of new high technology materials are included as well as data on those previously used. Emphasis is placed on the sources and processing of such materials in that results are frequently dependent on the way a material is prepared as well as its intrinsic constituents.

  10. ANTIMONY INDUCED CRYSTALLIZATION OF AMORPHOUS SILICON

    Institute of Scientific and Technical Information of China (English)

    Y. Wang; H.Z. Li; C.N. Yu; G.M. Wu; I. Gordon; P. Schattschneider; O. Van Der Biest

    2007-01-01

    Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE(molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.

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

    Science.gov (United States)

    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.

  12. Crystallization induced of amorphous silicon by nickel

    International Nuclear Information System (INIS)

    Schmidt, J.A; Rinaldi, P; Budini, N; Arce, R; Buitrago, R.H

    2008-01-01

    Polycrystalline silicon (pc-Si) deposited on glass substrates is a very promising material for the production of different electronic devices, like thin film transistors, active matrices or solar cells. The crystallization of the amorphous silicon to obtain pc-Si can be achieved with different processes, among which nickel-induced crystallization is because it requires low concentrations of the metal and low annealing temperatures. Nucleation and growth of crystalline silicon are measured by the formation of silicide NiSi 2 , which has a lattice constant very similar to that of Si, and acts as a seed upon which crystalline grains can develop. The size of the pc-Si final grain depends on many factors, such as the initial concentration of Ni, the annealing time and temperature, and the presence of other atoms in the Si structure. This work presents a study on the influence of these parameters on the silicon crystallization process induced by Ni. We deposited a series of hydrogenated amorphous silicon samples (a-Si:H) on glass substrates, using the plasma-enhanced chemical vapor deposition method (PE-CVD) with silane gas (SiH 4 ). The deposition temperature was 200 o C, and we prepared intrinsic samples (i), lightly doped with boron (p), heavily doped with boron (p + ) and heavily doped with phosphorous (n + ). Each sample was divided into eight portions, depositing different concentrations of Ni into each one using the cathodic sputtering method. The concentration of Ni was determined by atomic adsorption spectroscopy, and included from 1.5 1 0 15 to 1.5 1 0 16 at/cm 2 . Later the samples were submitted to different thermal treatments in a circulating nitrogen atmosphere. In order to avoid violent dehydrogenation of the a-Si:H that damages the samples, the annealing was carried out gradually. In a first stage the samples were heated at a velocity of 0.5 o C /min up to 400 o C, holding them for 24 hrs at this temperature in order to reach hydrogen effusion. Heating

  13. Silicon crystal growth using a liquid-feeding Czochralski method

    Science.gov (United States)

    Shiraishi, Yutaka; Kurosaka, Shoei; Imai, Masato

    1996-09-01

    Silicon single crystals with uniformity along the growth direction were grown using a new continuous Czochralski (CCZ) method. Polycrystalline silicon rods used as charge materials are melted by carbon heaters over a crucible without contact between the raw material and other substances. Using this method, silicon crystals with diameters as large as 6 or 8 inch and good uniformity along the growth direction were grown.

  14. Resistivity distribution of silicon single crystals using codoping

    Science.gov (United States)

    Wang, Jong Hoe

    2005-07-01

    Numerous studies including continuous Czochralski method and double crucible technique have been reported on the control of macroscopic axial resistivity distribution in bulk crystal growth. The simple codoping method for improving the productivity of silicon single-crystal growth by controlling axial specific resistivity distribution was proposed by Wang [Jpn. J. Appl. Phys. 43 (2004) 4079]. Wang [J. Crystal Growth 275 (2005) e73] demonstrated using numerical analysis and by experimental results that the axial specific resistivity distribution can be modified in melt growth of silicon crystals and relatively uniform profile is possible by B-P codoping method. In this work, the basic characteristic of 8 in silicon single crystal grown using codoping method is studied and whether proposed method has advantage for the silicon crystal growth is discussed.

  15. Tunable photoluminescence of porous silicon by liquid crystal infiltration

    International Nuclear Information System (INIS)

    Ma Qinglan; Xiong Rui; Huang Yuanming

    2011-01-01

    The photoluminescence (PL) of porous silicon films has been investigated as a function of the amount of liquid crystal molecules that are infiltrated into the constricted geometry of the porous silicon films. A typical nematic liquid crystal 4-pentyl-4'-cyanobiphenyl was employed in our experiment as the filler to modify the PL of porous silicon. It is found that the originally red PL of porous silicon films can be tuned to blue by simply adjusting the amount of liquid crystal molecules in the microchannels of the porous films. The chromaticity coordinates are calculated for the recorded PL spectra. The mechanism of the tunable PL is discussed. Our results have demonstrated that the luminescent properties of porous silicon films can be efficiently tuned by liquid crystal infiltration. - Highlights: → Liquid crystal infiltration can tune the photoluminescence of porous silicon. → Red emission of porous silicon can be switched to blue by the infiltration. → Chromaticity coordinates are calculated for the tuned emissions. → White emission is realized for porous silicon by liquid crystal infiltration.

  16. Future application of Czochralski crystal pulling for silicon

    Science.gov (United States)

    Matlcok, J. H.

    1985-08-01

    Czochralski (Cz) crystal pulling has been the predominant method used for preparing silicon single crystal for the past twenty years. The fundamental technology used has changed little. However, great strides have been made in learning how to make the crystals bigger and of better quality at ever increasing productivity rates. Currently charge sizes of 50 kg of polycrystal silicon are being used for production and crystals up to ten inches in diameter have been grown without major difficulty. The largest material actually being processed in silicon wafer form is 150 mm (6 inches) in diameter. Growing of crystals in a magnetic field has proved to be particularly useful for microscopic impurity control. Major developments in past years on equipment for Cz crystal pulling have included the automatic growth control of the diameter as well as the starting core of the crystal, the use of magnetic fields and around the crystal puller to supress convection, various recharging schemes for dopant control and the use of continuous liquid feed in the crystal puller. The latter, while far from being a reliable production process, is ideal in concept for major improvement in Cz crystal pulling. The Czochralski process will maintain its dominance of silicon crystal production for many years.

  17. Growth and characterization of heavily doped silicon crystals

    Energy Technology Data Exchange (ETDEWEB)

    Scala, R.; Porrini, M. [MEMC Electronic Materials SpA, via Nazionale 59, 39012 Merano (Italy); Borionetti, G. [MEMC Electronic Materials SpA, viale Gherzi 31, Novara (Italy)

    2011-08-15

    Silicon crystals grown with the Czochralski method are still the most common material used for the production of electronic devices. In recent years, a growing need of large diameter crystals with increasingly higher doping levels is observed, especially to support the expanding market of discrete devices and its trend towards lower and lower resistivity levels for the silicon substrate. The growth of such heavily doped, large-diameter crystals poses several new challenges to the crystal grower, and the presence of a high dopant concentration in the crystal affects significantly its main properties, requiring also the development of dedicated characterization techniques. This paper illustrates the recent advances in the growth and characterization of silicon crystals heavily doped with antimony, arsenic, phosphorus and boron. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Quality evaluation of resistivity-controlled silicon crystals

    Science.gov (United States)

    Wang, Jong Hoe

    2006-01-01

    The segregation phenomenon of dopants causes a low production yield of silicon crystal that meets the resistivity tolerance required by device manufacturers. In order to control the macroscopic axial resistivity distribution in bulk crystal growth, numerous studies including continuous Czochralski method and double crucible technique have been studied. The simple B-P codoping method for improving the productivity of p-type silicon single-crystal growth by controlling axial specific resistivity distribution was proposed by Wang [Jpn. J. Appl. Phys. 43 (2004) 4079]. In this work, the quality of Czochralski-grown silicon single crystals with a diameter 200 mm using B-P codoping method was studied from the chemical and structural points of view. It was found that the characteristics of B-P codoped wafers including the oxygen precipitation behavior and the grown-in defects are same as that of conventional B-doped Czochralski crystals.

  19. Silicon Crystal Growth by the Electromagnetic Czochralski (EMCZ) Method

    Science.gov (United States)

    Watanabe, Masahito; Eguchi, Minoru; Hibiya, Taketoshi

    1999-01-01

    A new method for growing silicon crystals by using electromagnetic force to rotate the melt without crucible rotation has been developed. We call it electromagnetic Czochralski (EMCZ) growth. An electromagnetic force in the azimuthal direction is generated in the melt by the interaction between an electric current (I) through the melt in the radial direction and a vertical magnetic field (B). The rotation rate (ωm) of the silicon melt is continuously changed from 0 to over 105 rpm under I = 0 to 8 A and B = 0 to 0.1 T. Thirty-mm-diameter silicon single crystals free of dislocations could be grown under two conditions: I = 2.0 A and B = 0.05 T (ωm = 105 rpm); and I =0.2 A and B = 0.1 T (ωm = 15 rpm). The oxygen concentration in the crystals was 8 ×1017 atoms/cm3 for the high rotation rate and 1×1017 atoms/cm3 for the low rotation rate. The oxygen-concentration distributions in the radial direction in both crystals were more homogeneous than those in the crystals grown by conventional CZ and/or MCZ growth. This new crystal-growth method can be easily adopted for growing large-diameter silicon crystals.

  20. Annealing effect of H+ -implanted single crystal silicon on strain and crystal structure

    International Nuclear Information System (INIS)

    Duo Xinzhong; Liu Weili; Zhang Miao; Gao Jianxia; Fu Xiaorong; Lin Chenglu

    2000-01-01

    The work focuses on the rocking curves of H + -implanted single silicon crystal detected by Four-Crystal X-ray diffractometer. The samples were annealed under different temperatures. Lattice defect in H + -implanted silicon crystals was detected by Rutherford Backscattering Spectrometry. It appeared that H-related complex did not crush until annealing temperature reached about 400 degree C. At that temperature H 2 was formed, deflated in silicon lattice and strained the lattice. But defects did not come into being in large quantity. The lattice was undamaged. When annealing temperature reached 500 degree C, strain induced by H 2 deflation crashed the silicon lattice. A large number of defects were formed. At the same time bubbles in the crystal and blister/flaking on the surface could be observed

  1. Tailoring of silicon crystals for relativistic-particle channeling

    International Nuclear Information System (INIS)

    Guidi, V.; Antonini, A.; Baricordi, S.; Logallo, F.; Malagu, C.; Milan, E.; Ronzoni, A.; Stefancich, M.; Martinelli, G.; Vomiero, A.

    2005-01-01

    In the last years, the research on channeling of relativistic particles has progressed considerably. A significant contribution has been provided by the development of techniques for quality improvement of the crystals. In particular, a planar etching of the surfaces of the silicon crystals proved useful to remove the superficial layer, which is a region very rich in imperfections, in turn leading to greater channeling efficiency. Micro-fabrication techniques, borrowed from silicon technology, may also be useful: micro-indentation and deposition of tensile or compressive layers onto silicon samples allow one to impart an even curvature to the samples. In this way, different topologies may be envisaged, such as a bent crystal for deflection of protons and ions or an undulator to force coherent oscillations of positrons and electrons

  2. Metal induced crystallization of silicon germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gjukic, M.

    2007-05-15

    In the framework of this thesis the applicability of the aluminium-induced layer exchange on binary silicon germanium alloys was studied. It is here for the first time shown that polycrstalline silicon-germanium layers can be fabricated over the whole composition range by the aluminium-induced layer exchange. The experimental results prove thet the resulting material exhibits a polycrystalline character with typocal grain sizes of 10-100 {mu}m. Raman measurements confirm that the structural properties of the resulting layers are because of the large crystallites more comparable with monocrystalline than with nano- or microcrystalline silicon-germanium. The alloy ratio of the polycrystalline layer correspondes to the chemical composition of the amorphous starting layer. The polycrystalline silicon-germanium layers possess in the range of the interband transitions a reflection spectrum, as it is otherwise only known from monocrystalline reference layers. The improvement of the absorption in the photovoltaically relevant spectral range aimed by the application of silicon-germanium could be also proved by absorption measurments. Strongly correlated with the structural properties of the polycrystalline layers and the electronic band structure resulting from this are beside the optical properties also the electrical properties of the material, especially the charge-carrier mobility and the doping concentration. For binary silicon-germanium layers the hole concentration of about 2 x 10{sup 18} cm{sup -3} for pure silicon increrases to about 5 x 10{sup 20} cm{sub -3} for pure germanium. Temperature-resolved measurements were applied in order to detect doping levels respectively semiconductor-metal transitions. In the last part of the thesis the hydrogen passivation of polycrystalline thin silicon-germanium layers, which were fabricated by means of aluminium-induced layer exchange, is treated.

  3. Orientation acoustic radiation of electrons in silicon thick crystal

    International Nuclear Information System (INIS)

    Alejnik, A.N.; Afanas'ev, S.G.; Vorob'ev, S.A.; Zabaev, V.N.; Il'in, S.I.; Kalinin, B.N.; Potylitsyn, A.P.

    1989-01-01

    Results of measuring orientation acoustic radiation of 900 and 500 MeV electrons during their movement along crystallographic axis in thick silicon crystal (h=20 mm thickness) are presented for the first time. Analysis of obtained results shows that dynamic mechanism describes rather completely the main regularities of orientation dependence of the amplitude of acoustic signal occuring under electron motion near crystallographic axis of the crystal. Phenomena of orientation acoustic radiation can be also used for investigation of solid bodies. Orientation both of thin and rather thick monocrystals can be conducted on the basis of dynamic mechanism of elastic wave excitation in crystals

  4. Passive Temperature Stabilization of Silicon Photonic Devices Using Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Joanna Ptasinski

    2014-03-01

    Full Text Available In this work we explore the negative thermo-optic properties of liquid crystal claddings for passive temperature stabilization of silicon photonic integrated circuits. Photonic circuits are playing an increasing role in communications and computing, but they suffer from temperature dependent performance variation. Most existing techniques aimed at compensation of thermal effects rely on power hungry Joule heating. We show that integrating a liquid crystal cladding helps to minimize the effects of a temperature dependent drift. The advantage of liquid crystals lies in their high negative thermo-optic coefficients in addition to low absorption at the infrared wavelengths.

  5. Observation of soliton compression in silicon photonic crystals

    Science.gov (United States)

    Blanco-Redondo, A.; Husko, C.; Eades, D.; Zhang, Y.; Li, J.; Krauss, T.F.; Eggleton, B.J.

    2014-01-01

    Solitons are nonlinear waves present in diverse physical systems including plasmas, water surfaces and optics. In silicon, the presence of two photon absorption and accompanying free carriers strongly perturb the canonical dynamics of optical solitons. Here we report the first experimental demonstration of soliton-effect pulse compression of picosecond pulses in silicon, despite two photon absorption and free carriers. Here we achieve compression of 3.7 ps pulses to 1.6 ps with photonic crystal waveguide and an ultra-sensitive frequency-resolved electrical gating technique to detect the ultralow energies in the nanostructured device. Strong agreement with a nonlinear Schrödinger model confirms the measurements. These results further our understanding of nonlinear waves in silicon and open the way to soliton-based functionalities in complementary metal-oxide-semiconductor-compatible platforms. PMID:24423977

  6. Thermally actuated resonant silicon crystal nanobalances

    Science.gov (United States)

    Hajjam, Arash

    As the potential emerging technology for next generation integrated resonant sensors and frequency references as well as electronic filters, micro-electro-mechanical resonators have attracted a lot of attention over the past decade. As a result, a wide variety of high frequency micro/nanoscale electromechanical resonators have recently been presented. MEMS resonators, as low-cost highly integrated and ultra-sensitive mass sensors, can potentially provide new opportunities and unprecedented capabilities in the area of mass sensing. Such devices can provide orders of magnitude higher mass sensitivity and resolution compared to Film Bulk Acoustic resonators (FBAR) or the conventional quartz and Surface Acoustic Wave (SAW) resonators due to their much smaller sizes and can be batch-fabricated and utilized in highly integrated large arrays at a very low cost. In this research, comprehensive experimental studies on the performance and durability of thermally actuated micromechanical resonant sensors with frequencies up to tens of MHz have been performed. The suitability and robustness of the devices have been demonstrated for mass sensing applications related to air-borne particles and organic gases. In addition, due to the internal thermo-electro-mechanical interactions, the active resonators can turn some of the consumed electronic power back into the mechanical structure and compensate for the mechanical losses. Therefore, such resonators can provide self-sustained-oscillation without the need for any electronic circuitry. This unique property has been deployed to demonstrate a prototype self-sustained sensor for air-borne particle monitoring. I have managed to overcome one of the obstacles for MEMS resonators, which is their relatively poor temperature stability. This is a major drawback when compared with the conventional quartz crystals. A significant decrease of the large negative TCF for the resonators has been attained by doping the devices with a high

  7. Nanostructured Porous Silicon Photonic Crystal for Applications in the Infrared

    Directory of Open Access Journals (Sweden)

    G. Recio-Sánchez

    2012-01-01

    Full Text Available In the last decades great interest has been devoted to photonic crystals aiming at the creation of novel devices which can control light propagation. In the present work, two-dimensional (2D and three-dimensional (3D devices based on nanostructured porous silicon have been fabricated. 2D devices consist of a square mesh of 2 μm wide porous silicon veins, leaving 5×5 μm square air holes. 3D structures share the same design although multilayer porous silicon veins are used instead, providing an additional degree of modulation. These devices are fabricated from porous silicon single layers (for 2D structures or multilayers (for 3D structures, opening air holes in them by means of 1 KeV argon ion bombardment through the appropriate copper grids. For 2D structures, a complete photonic band gap for TE polarization is found in the thermal infrared range. For 3D structures, there are no complete band gaps, although several new partial gaps do exist in different high-symmetry directions. The simulation results suggest that these structures are very promising candidates for the development of low-cost photonic devices for their use in the thermal infrared range.

  8. Wetting and crystallization at grain boundaries: Origin of aluminum-induced crystallization of amorphous silicon

    International Nuclear Information System (INIS)

    Wang, J.Y.; He, D.; Zhao, Y.H.; Mittemeijer, E.J.

    2006-01-01

    It has been shown experimentally that the grain boundaries in aluminium in contact with amorphous silicon are the necessary agents for initiation of the crystallization of silicon upon annealing temperatures as low as 438 K. Thermodynamic analysis has shown (i) that Si can 'wet' the Al grain boundaries due to the favorable Si/Al interface energy as compared to the Al grain-boundary energy and (ii) that Si at the Al grain boundaries can maintain its amorphous state up to a thickness of about 1.0 nm. Beyond that thickness crystalline Si develops at the Al grain boundaries

  9. The tensile effect on crack formation in single crystal silicon irradiated by intense pulsed ion beam

    Science.gov (United States)

    Liang, Guoying; Shen, Jie; Zhang, Jie; Zhong, Haowen; Cui, Xiaojun; Yan, Sha; Zhang, Xiaofu; Yu, Xiao; Le, Xiaoyun

    2017-10-01

    Improving antifatigue performance of silicon substrate is very important for the development of semiconductor industry. The cracking behavior of silicon under intense pulsed ion beam irradiation was studied by numerical simulation in order to understand the mechanism of induced surface peeling observed by experimental means. Using molecular dynamics simulation based on Stillinger Weber potential, tensile effect on crack growth and propagation in single crystal silicon was investigated. Simulation results reveal that stress-strain curves of single crystal silicon at a constant strain rate can be divided into three stages, which are not similar to metal stress-strain curves; different tensile load velocities induce difference of single silicon crack formation speed; the layered stress results in crack formation in single crystal silicon. It is concluded that the crack growth and propagation is more sensitive to strain rate, tensile load velocity, stress distribution in single crystal silicon.

  10. Temperature effect on phase states of quartz nano-crystals in silicon single crystal

    International Nuclear Information System (INIS)

    Kalanov, M.U.; Ibragimova, E.M.; Khamraeva, R.N.; Rustamova, V.M.; Ummatov, Kh.D.

    2006-01-01

    Full text: Oxygen penetrates into the silicon lattice up to the concentration of 2·10 18 cm -3 in the course of growing [1]. By the author's opinion at a low oxygen content the formation of solid solution is possible in the local defect places of the silicon single crystal lattice due to the difference in effective ion radius of oxygen and silicon (r O 0.176 and r Si = 0.065 nm). Upon reaching some critical content (∼ 10 17 cm -3 ), it becomes favorable energetically for oxygen ions to form precipitates (SiO x ) and finally a dielectric layer (stoichiometric inclusions of SiO 2 ). It was shown later that depending on the growth conditions, indeed the quartz crystal inclusions are formed in the silicon single crystals at an amount of 0.3 /0.5 wt. % [2]. However the authors did not study a phase state of the quartz inclusions. Therefore the aim of this work was to study a phase state of the quartz inclusions in silicon crystal at various temperatures. We examined the silicon single crystals grown by Czochralski technique, which were cut in (111) plane in the form of disk of 20 mm diameter and 1.5 thickness and had hole conductivity with the specific resistance ρ o ≅ 1/10 Ohm cm. The dislocation density was N D ≅ 10 1 /10 3 cm -2 , the concentrations of oxygen and boron were N 0 ≅ 2/ 4·10 17 cm -3 and N B ≅ 3*10 15 cm -3 . Structure was analyzed at the set-up DRON-UM1 with high temperature supply UVD-2000 ( CuK = 0.1542 nm) at the temperatures of 300, 1173 and 1573 K measured with platinum-platinum-rhodium thermocouple. The high temperature diffraction spectrum measured at 1573 K in the angle range (2Θ≅10/70 d egree ) there is only one main structure reflection (111) with a high intensity and d/n ≅ 0.3136 nm (2 Θ≅ 28.5 d egree ) from the matrix lattice of silicon single crystal. The weak line at 2 Θ≅ 25.5 d egree ( d/n≅0.3136 nm) is β component of the main reflection (111), and the weak structure peak at 2Θ≅59 d egree ( d/n≅ 0.1568 nm

  11. Silicon photonic crystal nanostructures for refractive index sensing

    DEFF Research Database (Denmark)

    Dorfner, Dominic; Hürlimann, T.; Zabel, T.

    2008-01-01

    The authors present the fabrication and optical investigation of Silicon on Insulator photonic crystal drop-filters for use as refractive index sensors. Two types of defect nanocavities (L3 and H1-r) are embedded between two W1 photonic crystal waveguides to evanescently route light at the cavity...... mode frequency between input and output waveguides. Optical characterization of the structures in air and various liquids demonstrate detectivities in excess of n=n = 0:018 and n=n = 0:006 for the H1-r and L3 cavities, respectively. The measured cavity-frequencies and detector refractive index...... responsivities are in good agreement with simulations, demonstrating that the method provides a background free transducer signal with frequency selective addressing of a specic area of the sensor chip....

  12. Phosphorus diffusion in float zone silicon crystal growth

    DEFF Research Database (Denmark)

    Larsen, Theis Leth

    2000-01-01

    This Ph.D thesis encompasses a global numerical simulation of the needle-eye oat zone process, used to grow silicon single crystals. The numerical models includes coupled electromagnetic and free surface models and a global heat transfer model, with moving boundaries. An axisymmetric uidow model......, including centrifugal, buoyancy, thermocapillary and electromagnetic forces, is used to determine flow field, after the phase boundaries have been determined, by the heat transfer model. A finite element model for calculating dopant transport, using the calculated unsteady flow field, has been developed...... within this project. This model has furthermore been expanded to two equations coupled by a non-zero right hand side, for simulating transport of point defects in the crystal during growth. Free surface shapes and induced electric surface current are calculated for t wo different 4'' congurations and a 0...

  13. Silicon photonic crystal all-optical logic gates

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Yulan [State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871 (China); Hu, Xiaoyong, E-mail: xiaoyonghu@pku.edu.cn [State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871 (China); Gong, Qihuang, E-mail: qhgong@pku.edu.cn [State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871 (China)

    2013-01-03

    All-optical logic gates, including OR, XOR, NOT, XNOR, and NAND gates, are realized theoretically in a two-dimensional silicon photonic crystal using the light beam interference effect. The ingenious photonic crystal waveguide component design, the precisely controlled optical path difference, and the elaborate device configuration ensure the simultaneous realization of five types of logic gate with low-power and a contrast ratio between the logic states of “1” and “0” as high as 20 dB. High power is not necessary for operation of these logic gate devices. This offers a simple and effective approach for the realization of integrated all-optical logic devices.

  14. Crystallization of Electrodeposited Germanium Thin Film on Silicon (100).

    Science.gov (United States)

    Abidin, Mastura Shafinaz Zainal; Matsumura, Ryo; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Muta, Shunpei; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

    2013-11-06

    We report the crystallization of electrodeposited germanium (Ge) thin films on n-silicon (Si) (100) by rapid melting process. The electrodeposition was carried out in germanium (IV) chloride: propylene glycol (GeCl₄:C₃H₈O₂) electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD) images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA) at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm -1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm -1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES) reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

  15. Crystallization of Electrodeposited Germanium Thin Film on Silicon (100

    Directory of Open Access Journals (Sweden)

    Abdul Manaf Hashim

    2013-11-01

    Full Text Available We report the crystallization of electrodeposited germanium (Ge thin films on n-silicon (Si (100 by rapid melting process. The electrodeposition was carried out in germanium (IV chloride: propylene glycol (GeCl4:C3H8O2 electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm−1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm−1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

  16. Defects in silicon effect on device performance and relationship to crystal growth conditions

    Science.gov (United States)

    Jastrzebski, L.

    1985-01-01

    A relationship between material defects in silicon and the performance of electronic devices will be described. A role which oxygen and carbon in silicon play during the defects generation process will be discussed. The electronic properties of silicon are a strong function of the oxygen state in the silicon. This state controls mechanical properties of silicon efficiency for internal gettering and formation of defects in the device's active area. In addition, to temperature, time, ambience, and the cooling/heating rates of high temperature treatments, the oxygen state is a function of the crystal growth process. The incorporation of carbon and oxygen into silicon crystal is controlled by geometry and rotation rates applied to crystal and crucible during crystal growths. Also, formation of nucleation centers for oxygen precipitation is influenced by the growth process, although there is still a controversy which parameters play a major role. All these factors will be reviewed with special emphasis on areas which are still ambiguous and controversial.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  18. Optical nonreciprocal transmission in an asymmetric silicon photonic crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zheng; Chen, Juguang; Ji, Mengxi; Huang, Qingzhong; Xia, Jinsong; Wang, Yi, E-mail: yingwu2@126.com, E-mail: ywangwnlo@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wu, Ying, E-mail: yingwu2@126.com, E-mail: ywangwnlo@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2015-11-30

    An optical nonreciprocal transmission (ONT) is realized by employing the nonlinear effects in a compact asymmetric direct-coupled nanocavity-waveguide silicon photonic crystal structure with a high loaded quality factor (Q{sub L}) of 42 360 and large extinction ratio exceeding 30 dB. Applying a single step lithography and successive etching, the device can realize the ONT in an individual nanocavity, alleviating the requirement to accurately control the resonance of the cavities. A maximum nonreciprocal transmission ratio of 21.1 dB as well as a working bandwidth of 280 pm in the telecommunication band are obtained at a low input power of 76.7 μW. The calculated results by employing a nonlinear coupled-mode model are in good agreement with the experiment.

  19. A liquid-crystal-on-silicon color sequential display using frame buffer pixel circuits

    Science.gov (United States)

    Lee, Sangrok

    Next generation liquid-crystal-on-silicon (LCOS) high definition (HD) televisions and image projection displays will need to be low-cost and high quality to compete with existing systems based on digital micromirror devices (DMDs), plasma displays, and direct view liquid crystal displays. In this thesis, a novel frame buffer pixel architecture that buffers data for the next image frame while displaying the current frame, offers such a competitive solution is presented. The primary goal of the thesis is to demonstrate the LCOS microdisplay architecture for high quality image projection displays and at potentially low cost. The thesis covers four main research areas: new frame buffer pixel circuits to improve the LCOS performance, backplane architecture design and testing, liquid crystal modes for the LCOS microdisplay, and system integration and demonstration. The design requirements for the LCOS backplane with a 64 x 32 pixel array are addressed and measured electrical characteristics matches to computer simulation results. Various liquid crystal (LC) modes applicable for LCOS microdisplays and their physical properties are discussed. One- and two-dimensional director simulations are performed for the selected LC modes. Test liquid crystal cells with the selected LC modes are made and their electro-optic effects are characterized. The 64 x 32 LCOS microdisplays fabricated with the best LC mode are optically tested with interface circuitry. The characteristics of the LCOS microdisplays are summarized with the successful demonstration.

  20. Thermal neutron scattering kernels for sapphire and silicon single crystals

    International Nuclear Information System (INIS)

    Cantargi, F.; Granada, J.R.; Mayer, R.E.

    2015-01-01

    Highlights: • Thermal cross section libraries for sapphire and silicon single crystals were generated. • Debye model was used to represent the vibrational frequency spectra to feed the NJOY code. • Sapphire total cross section was measured at Centro Atómico Bariloche. • Cross section libraries were validated with experimental data available. - Abstract: Sapphire and silicon are materials usually employed as filters in facilities with thermal neutron beams. Due to the lack of the corresponding thermal cross section libraries for those materials, necessary in calculations performed in order to optimize beams for specific applications, here we present the generation of new thermal neutron scattering kernels for those materials. The Debye model was used in both cases to represent the vibrational frequency spectra required to feed the NJOY nuclear data processing system in order to produce the corresponding libraries in ENDF and ACE format. These libraries were validated with available experimental data, some from the literature and others obtained at the pulsed neutron source at Centro Atómico Bariloche

  1. Crystal imperfection studies of pure and silicon substituted hydroxyapatite using Raman and XRD.

    Science.gov (United States)

    Zou, Shuo; Huang, Jie; Best, Serena; Bonfield, William

    2005-12-01

    Hydroxyapatite (HA) is important in biomedical applications because of its chemical similarity to the mineral content of bone and its consequent bioactivity. Silicon substitution into the hydroxyapatite crystal lattice was found to enhance its bioactivity both in vitro and in vivo [1, 2]. However, the mechanism for the enhancement is still not well understood. In this paper, the crystal imperfections introduced by silicon substitution were studied using XRD and Raman spectroscopy. It was found that silicon substitution did not introduce microstrain, but deceased the crystal size in the hk0 direction. Three new vibration modes and peak broadening were observed in Raman spectra following silicon incorporation. The imperfections introduced by silicon substitution may play a role in enhancing bioactivity. A phenomenological relationship between the width of the PO4 v1 peak and crystal size was established.

  2. Enhanced light emission in photonic crystal nanocavities with Erbium-doped silicon nanocrystals

    International Nuclear Information System (INIS)

    Makarova, Maria; Sih, Vanessa; Vuckovic, Jelena; Warga, Joe; Li Rui; Dal Negro, Luca

    2008-01-01

    Photonic crystal nanocavities are fabricated in silicon membranes covered by thermally annealed silicon-rich nitride films with Erbium-doped silicon nanocrystals. Silicon nitride films were deposited by sputtering on top of silicon on insulator wafers. The nanocavities were carefully designed in order to enhance emission from the nanocrystal sensitized Erbium at the 1540 nm wavelength. Experimentally measured quality factors of ∼6000 were found to be consistent theoretical predictions. The Purcell factor of 1.4 was estimated from the observed 20-fold enhancement of Erbium luminescence

  3. Automatically controlled facilities for irradiation of silicon crystals at the Rossendorf Research Reactor

    International Nuclear Information System (INIS)

    Ross, R.

    1988-01-01

    This report describes the facilities for neutron transmutation doping of silicon in GDR. The irradiation of silicon single crystals began at Rossendorf in 1978 with simple equipment. Only a small amount of silicon could be irradiated in it. The fast increasing need of NTD-silicon made it necessary to design and construct new and better facilities. The new facilities are capable of irradiating silicon from 2'' to 3'' in diameter. The irradiation process takes place automatically with the assistance of a computer. Material produced has an axial homogeneity of ± 7%. Irradiation riggs, techniques, irradiation control and quality control are discussed. (author). 4 figs

  4. Crystals in brain and meninges in primary hyperoxaluria and oxalosis.

    Science.gov (United States)

    Haqqani, M T

    1977-01-01

    A case of primary hyperoxaluria and oxalosis with chronic renal failure, crystalline myocarditis, and disseminated calcium oxalate crystal deposition in various tissues including the brain and meninges is described. Deposition of crystals in brain and meninges is exceptionally rare in primary oxalosis. Images PMID:838867

  5. ARROW-based silicon-on-insulator photonic crystal waveguides with reduced losses

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Novitsky, A.; Zhilko, V.V.

    2006-01-01

    We employ an antiresonant reflecting layers arrangement with silicon-on-insulator based photonic crystal waveguides. The 3D FDTD numerical modelling reveals improved transmission in such structures with a promising potential for their application in photonic circuits.......We employ an antiresonant reflecting layers arrangement with silicon-on-insulator based photonic crystal waveguides. The 3D FDTD numerical modelling reveals improved transmission in such structures with a promising potential for their application in photonic circuits....

  6. Optical microcavities based on surface modes in two-dimensional photonic crystals and silicon-on-insulator photonic crystals

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Qiu, M.

    2007-01-01

    Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor is gr...... is gradually enhanced and the resonant frequency converges to that of the corresponding surface mode in the photonic crystals. These structures have potential applications such as sensing.......Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor...

  7. Buckling of Single-Crystal Silicon Nanolines under Indentation

    Directory of Open Access Journals (Sweden)

    Min K. Kang

    2008-01-01

    Full Text Available Atomic force microscope-(AFM- based indentation tests were performed to examine mechanical properties of parallel single-crystal silicon nanolines (SiNLs of sub-100-nm line width, fabricated by a process combining electron-beam lithography and anisotropic wet etching. The SiNLs have straight and nearly atomically flat sidewalls, and the cross section is almost perfectly rectangular with uniform width and height along the longitudinal direction. The measured load-displacement curves from the indentation tests show an instability with large displacement bursts at a critical load ranging from 480 μN to 700 μN. This phenomenon is attributed to a transition of the buckling mode of the SiNLs under indentation. Using a set of finite element models with postbuckling analyses, we analyze the indentation-induced buckling modes and investigate the effects of tip location, contact friction, and substrate deformation on the critical load of mode transition. The results demonstrate a unique approach for the study of nanomaterials and patterned nanostructures via a combination of experiments and modeling.

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

    International Nuclear Information System (INIS)

    Irwin, R.B.

    1984-01-01

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

  9. Silicon-based photonic crystals fabricated using proton beam writing combined with electrochemical etching method.

    Science.gov (United States)

    Dang, Zhiya; Breese, Mark Bh; Recio-Sánchez, Gonzalo; Azimi, Sara; Song, Jiao; Liang, Haidong; Banas, Agnieszka; Torres-Costa, Vicente; Martín-Palma, Raúl José

    2012-07-23

    A method for fabrication of three-dimensional (3D) silicon nanostructures based on selective formation of porous silicon using ion beam irradiation of bulk p-type silicon followed by electrochemical etching is shown. It opens a route towards the fabrication of two-dimensional (2D) and 3D silicon-based photonic crystals with high flexibility and industrial compatibility. In this work, we present the fabrication of 2D photonic lattice and photonic slab structures and propose a process for the fabrication of 3D woodpile photonic crystals based on this approach. Simulated results of photonic band structures for the fabricated 2D photonic crystals show the presence of TE or TM gap in mid-infrared range.

  10. High-Q silicon-on-insulator slot photonic crystal cavity infiltrated by a liquid

    International Nuclear Information System (INIS)

    Caër, Charles; Le Roux, Xavier; Cassan, Eric

    2013-01-01

    We report the experimental realization of a high-Q slot photonic crystal cavity in Silicon-On-Insulator (SOI) configuration infiltrated by a liquid. Loaded Q-factor of 23 000 is measured at telecom wavelength. The intrinsic quality factor inferred from the transmission spectrum is higher than 200 000, which represents a record value for slot photonic crystal cavities on SOI, whereas the maximum of intensity of the cavity is roughly equal to 20% of the light transmitted in the waveguide. This result makes filled slot photonic crystal cavities very promising for silicon-based light emission and ultrafast nonlinear optics

  11. Effect of starting point formation on the crystallization of amorphous silicon films by flash lamp annealing

    Science.gov (United States)

    Sato, Daiki; Ohdaira, Keisuke

    2018-04-01

    We succeed in the crystallization of hydrogenated amorphous silicon (a-Si:H) films by flash lamp annealing (FLA) at a low fluence by intentionally creating starting points for the trigger of explosive crystallization (EC). We confirm that a partly thick a-Si part can induce the crystallization of a-Si films. A periodic wavy structure is observed on the surface of polycrystalline silicon (poly-Si) on and near the thick parts, which is a clear indication of the emergence of EC. Creating partly thick a-Si parts can thus be effective for the control of the starting point of crystallization by FLA and can realize the crystallization of a-Si with high reproducibility. We also compare the effects of creating thick parts at the center and along the edge of the substrates, and a thick part along the edge of the substrates leads to the initiation of crystallization at a lower fluence.

  12. Temperature fields in a growing solar silicon crystal

    Directory of Open Access Journals (Sweden)

    Kondrik A. I.

    2012-06-01

    Full Text Available The optimal thermal terms for growing by Czochralski method Si single-crystals, suitable for making photoelectric energy converters, has been defined by the computer simulation method. Dependences of temperature fields character and crystallization front form on the diameter of the crystal, stage and speed of growing, and also on correlation between diameter and height of the crystal has been studied.

  13. Thin Single Crystal Silicon Solar Cells on Ceramic Substrates: November 2009 - November 2010

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.; Ravi, K. V.

    2011-06-01

    In this program we have been developing a technology for fabricating thin (< 50 micrometres) single crystal silicon wafers on foreign substrates. We reverse the conventional approach of depositing or forming silicon on foreign substrates by depositing or forming thick (200 to 400 micrometres) ceramic materials on high quality single crystal silicon films ~ 50 micrometres thick. Our key innovation is the fabrication of thin, refractory, and self-adhering 'handling layers or substrates' on thin epitaxial silicon films in-situ, from powder precursors obtained from low cost raw materials. This 'handling layer' has sufficient strength for device and module processing and fabrication. Successful production of full sized (125 mm X 125 mm) silicon on ceramic wafers with 50 micrometre thick single crystal silicon has been achieved and device process flow developed for solar cell fabrication. Impurity transfer from the ceramic to the silicon during the elevated temperature consolidation process has resulted in very low minority carrier lifetimes and resulting low cell efficiencies. Detailed analysis of minority carrier lifetime, metals analysis and device characterization have been done. A full sized solar cell efficiency of 8% has been demonstrated.

  14. Development of low-cost silicon crystal growth techniques for terrestrial photovoltaic solar energy conversion

    Science.gov (United States)

    Zoutendyk, J. A.

    1976-01-01

    Because of the growing need for new sources of electrical energy, photovoltaic solar energy conversion is being developed. Photovoltaic devices are now being produced mainly from silicon wafers obtained from the slicing and polishing of cylindrically shaped single crystal ingots. Inherently high-cost processes now being used must either be eliminated or modified to provide low-cost crystalline silicon. Basic to this pursuit is the development of new or modified methods of crystal growth and, if necessary, crystal cutting. If silicon could be grown in a form requiring no cutting, a significant cost saving would potentially be realized. Therefore, several techniques for growth in the form of ribbons or sheets are being explored. In addition, novel techniques for low-cost ingot growth and cutting are under investigation.

  15. Crystal growth for high-efficiency silicon solar cells workshop: Summary

    Science.gov (United States)

    Dumas, K. A.

    1985-01-01

    The state of the art in the growth of silicon crystals for high-efficiency solar cells are reviewed, sheet requirements are defined, and furture areas of research are identified. Silicon sheet material characteristics that limit cell efficiencies and yields were described as well as the criteria for the ideal sheet-growth method. The device engineers wish list to the material engineer included: silicon sheet with long minority carrier lifetime that is uniform throughout the sheet, and which doesn't change during processing; and sheet material that stays flat throughout device processing, has uniform good mechanical strength, and is low cost. Impurities in silicon solar cells depreciate cell performance by reducing diffusion length and degrading junctions. The impurity behavior, degradation mechanisms, and variations in degradation threshold with diffusion length for silicon solar cells were described.

  16. Anisotropy effect of crater formation on single crystal silicon surface under intense pulsed ion beam irradiation

    Science.gov (United States)

    Shen, Jie; Yu, Xiao; Zhang, Jie; Zhong, Haowen; Cui, Xiaojun; Liang, Guoying; Yu, Xiang; Huang, Wanying; Shahid, Ijaz; Zhang, Xiaofu; Yan, Sha; Le, Xiaoyun

    2018-04-01

    Due to the induced extremely fast thermal and dynamic process, Intense Pulsed Ion Beam (IPIB) is widely applied in material processing, which can bring enhanced material performance and surface craters as well. To investigate the craters' formation mechanism, a specific model was built with Finite Element Methods (FEM) to simulate the thermal field on irradiated single crystal silicon. The direct evidence for the existence of the simulated 6-fold rotational symmetric thermal distribution was provided by electron microscope images obtained on single crystal silicon. The correlation of the experiment and simulation is of great importance to understand the interaction between IPIB and materials.

  17. Photonic and Plasmonic Guided Modes in Graphene-Silicon Photonic Crystals

    DEFF Research Database (Denmark)

    Gu, Tingyi; Andryieuski, Andrei; Hao, Yufeng

    2015-01-01

    We report the results of systematic studies of plasmonic and photonic guided modes in large-area single-layer graphene integrated into a nanostructured silicon substrate. The interaction of light with graphene and substrate photonic crystals can be classified in distinct regimes depending......, filters, sensors, and photodetectors utilizing silicon photonic platforms....... on the relation of the photonic crystal lattice constant and the relevant modal wavelengths, that is, plasmonic, photonic, and free-space. By optimizing the design of the substrate, these resonant modes can increase the absorption of graphene in the infrared, facilitating enhanced performance of modulators...

  18. Experimental studies on using silicon photodiode as read-out component of CsI(Tl) crystal

    International Nuclear Information System (INIS)

    He Jingtang; Chen Duanbao; Li Zuhao; Mao Yufang; Dong Xiaoli

    1996-01-01

    Experimental studies on using silicon photodiode as the read-out component of CsI(Tl) crystal are reported. The read-out properties of two different types of silicon photodiode produced by Hamamatsu were measured, including relations between energy resolution and bias, shaping time, sensitive area of photodiode and the dimension of the crystal

  19. Hydrogenated amorphous silicon nitride photonic crystals for improved-performance surface electromagnetic wave biosensors.

    Science.gov (United States)

    Sinibaldi, Alberto; Descrovi, Emiliano; Giorgis, Fabrizio; Dominici, Lorenzo; Ballarini, Mirko; Mandracci, Pietro; Danz, Norbert; Michelotti, Francesco

    2012-10-01

    We exploit the properties of surface electromagnetic waves propagating at the surface of finite one dimensional photonic crystals to improve the performance of optical biosensors with respect to the standard surface plasmon resonance approach. We demonstrate that the hydrogenated amorphous silicon nitride technology is a versatile platform for fabricating one dimensional photonic crystals with any desirable design and operating in a wide wavelength range, from the visible to the near infrared. We prepared sensors based on photonic crystals sustaining either guided modes or surface electromagnetic waves, also known as Bloch surface waves. We carried out for the first time a direct experimental comparison of their sensitivity and figure of merit with surface plasmon polaritons on metal layers, by making use of a commercial surface plasmon resonance instrument that was slightly adapted for the experiments. Our measurements demonstrate that the Bloch surface waves on silicon nitride photonic crystals outperform surface plasmon polaritons by a factor 1.3 in terms of figure of merit.

  20. Plasmonic and Photonic Modes Excitation in Graphene on Silicon Photonic Crystal Membrane

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Gu, Tingyi; Hao, Yufeng

    . Being deposited on a silicon photonic crystal membrane graphene serves as a highly promising system for modern optoelectronics with rich variety of possible regimes. Depending on the relation between the photonic crystal lattice constant and wavelengths (plasmonic, photonic and free-space) we identify...... characterization. Measured data are well correlated with the numerical analysis. Combined graphene – silicon photonic crystal membranes can find applications for infrared absorbers, modulators, filters, sensors and photodetectors....... four different interaction schemes. We refer to them as metamaterial, plasmonic, photonic and diffraction grating regimes based on the principle character of light interactions with the graphene deposited on the Si photonic crystal membrane. The optimal configurations for resonant excitation of modes...

  1. Radiation emission phenomena in bent silicon crystals: Theoretical and experimental studies with 120 GeV/c positrons

    International Nuclear Information System (INIS)

    Lietti, D.; Bagli, E.; Baricordi, S.; Berra, A.; Bolognini, D.; Chirkov, P.N.; Dalpiaz, P.; Della Mea, G.; De Salvador, D.; Hasan, S.; Guidi, V.; Maisheev, V.A.

    2012-01-01

    The radiation emission phenomena in bent silicon crystals have been thoroughly investigated at the CERN SPS-H4 beamline. The incoming and outgoing trajectories of charged particles impinging on a silicon strip crystal have been reconstructed by high precision silicon microstrip detectors. A spectrometer method has been exploited to measure the radiation emission spectra both in volume reflection and in channeling. The theoretical method used to evaluate the photon spectra is presented and compared with the experimental results.

  2. Molecular dynamics studies of the ion beam induced crystallization in silicon

    International Nuclear Information System (INIS)

    Marques, L.A.; Caturla, M.J.; Huang, H.

    1995-01-01

    We have studied the ion bombardment induced amorphous-to-crystal transition in silicon using molecular dynamics techniques. The growth of small crystal seeds embedded in the amorphous phase has been monitored for several temperatures in order to get information on the effect of the thermal temperature increase introduced by the incoming ion. The role of ion-induced defects on the growth has been also studied

  3. Liquid crystal designs for high-contrast field sequential color liquid crystal on silicon (LCoS) microdisplays (Invited Paper)

    Science.gov (United States)

    Anderson, James; Chen, Cheng; Bos, Philip J.

    2005-04-01

    Single or dual panel microdisplay systems are becoming more popular in the marketplace. Consequently, Liquid Crystal on Silicon (LCoS) microdisplays are constantly being pushed to achieve faster switching times as well as higher contrast, while becoming simpler and allowing simpler optics engine design. Currently, most products use a Twisted Nematic (TN) mode with a retardation film. The most promising solution in research now is the Vertically Aligned Nematic (VAN) mode, which does not require a retarder.

  4. Annihilation of unthermalized positrons in a silicon single crystal at 770K

    International Nuclear Information System (INIS)

    Zaitsev, Yu.E.; Mungir, L.; Ue'pe, L.R.

    1984-01-01

    A model is considered for the annihilation of nonrelativistic positrons from quantized states in lattice channels. Annihilation gamma rays of energy over 511 keV have been observed when the positrons from an Na 22 source strike a silicon single crystal at 77 0 K. The experimental results agree well with the proposed model

  5. Photonic and plasmonic guided modes in graphene-silicon photonic crystals

    DEFF Research Database (Denmark)

    Gu, Tingyi; Andryieuski, Andrei; Hao, Yufeng

    2016-01-01

    We report the results of systematic studies of plasmonic and photonic guided modes in large-area single-layer graphene integrated into a nanostructured silicon substrate. The interaction of light with graphene and substrate photonic crystals can be classified in distinct regimes of plasmonic...... and photonic modes....

  6. Irradiation of electron with high energy induced micro-crystallization of amorphous silicon

    International Nuclear Information System (INIS)

    Zhong Yule; Huang Junkai; Liu Weiping; Li Jingna

    2001-01-01

    Amorphous silicon is amorphous alloy of Si-H. It is random network of silicon with some hydrogen. And its structure has many unstable bonds as weak bonds of Si-Si and distortion bonds of all kinds. The bonds was broken or was out of shape by light and electrical ageing. It induced increase of defective state that causes character of material going to bad. This drawback will be overcome after micro-crystallization of amorphous silicon. It was discovered that a-Si:H was micro-crystallized by irradiated of electrons with energy of 0.3-0.5 MeV, density of electronic beam of 1.3 x 10 19 cm -1 s -1 and irradiated time of 10-600 s. Size of grain is 10-20 nm. Thick of microcrystalline lager is 25-250 nm

  7. Modelling of thermal field and point defect dynamics during silicon single crystal growth using CZ technique

    Science.gov (United States)

    Sabanskis, A.; Virbulis, J.

    2018-05-01

    Mathematical modelling is employed to numerically analyse the dynamics of the Czochralski (CZ) silicon single crystal growth. The model is axisymmetric, its thermal part describes heat transfer by conduction and thermal radiation, and allows to predict the time-dependent shape of the crystal-melt interface. Besides the thermal field, the point defect dynamics is modelled using the finite element method. The considered process consists of cone growth and cylindrical phases, including a short period of a reduced crystal pull rate, and a power jump to avoid large diameter changes. The influence of the thermal stresses on the point defects is also investigated.

  8. Monochromator for synchrotron light with temperature controlled by electrical current on silicon crystal

    Energy Technology Data Exchange (ETDEWEB)

    Cusatis, Cesar; Souza, Paulo E.N. [Universidade Federal do Parana (LORXI/UFPR), Curitiba, PR (Brazil). Dept. de Fisica. Lab. de Optica de Raios X e Instrumentacao; Franco, Margareth Kobayaski; Kakuno, Edson [Laboratorio Nacional de Luz Sincroton (LNLS), Campinas, SP (Brazil); Gobbi, Angelo; Carvalho Junior, Wilson de [Centro de Pesquisa e Desenvolvimento em Telecomunicacoes (CPqD), Campinas, SP (Brazil)

    2011-07-01

    Full text. doped silicon crystal was used simultaneously as a monochromator, sensor and actuator in such way that its temperature could be controlled. Ohmic contacts allowed resistance measurements on a perfect silicon crystal, which were correlated to its temperature. Using the ohmic contacts, an electrical current caused Joule heating on the monochromator that was used to control its temperature. A simple stand-alone electronic box controlled the system. The device was built and tested with white beam synchrotron light on the double crystal monochromator of the XRD line of LNLS, Laboratorio Nacional de Luz Sincrotron, Campinas. The first crystal of a double crystal monochromator determines the energy that is delivered to a synchrotron experimental station and its temperature instability is a major source of energy and intensity instability. If the (333) silicon monochromator is at theta Bragg near 45 degree the variation of the diffraction angle is around one second of arc per degree Kelvin. It may take several minutes for the first crystal temperature to stabilize at the beginning of the station operation when the crystal and its environment are cold. With water refrigeration, the average overall temperature of the crystal may be constant, but the temperature of the surface changes with and without the white beam. The time used to wait for stabilization of the beam energy/intensity is lost unless the temperature of the crystal surface is kept constant. One solution for keeping the temperature of the monochromator and its environment constant or nearly constant is Joule heating it with a controlled small electrical current flowing on the surface of a doped perfect crystal. When the white beam is on, this small amount of extra power will be more concentrated at the beam footpath because the resistance is lower in this region due to the higher temperature. In addition, if the crystal itself is used to detect the temperature variation by measuring the electrical

  9. Three-dimensional modelling of thermal stress in floating zone silicon crystal growth

    Science.gov (United States)

    Plate, Matiss; Krauze, Armands; Virbulis, Jānis

    2018-05-01

    During the growth of large diameter silicon single crystals with the industrial floating zone method, undesirable level of thermal stress in the crystal is easily reached due to the inhomogeneous expansion as the crystal cools down. Shapes of the phase boundaries, temperature field and elastic material properties determine the thermal stress distribution in the solid mono crystalline silicon during cylindrical growth. Excessive stress can lead to fracture, generation of dislocations and altered distribution of intrinsic point defects. Although appearance of ridges on the crystal surface is the decisive factor of a dislocation-free growth, the influence of these ridges on the stress field is not completely clear. Here we present the results of thermal stress analysis for 4” and 5” diameter crystals using a quasi-stationary three dimensional mathematical model including the material anisotropy and the presence of experimentally observed ridges which cannot be addressed with axis-symmetric models. The ridge has a local but relatively strong influence on thermal stress therefore its relation to the origin of fracture is hypothesized. In addition, thermal stresses at the crystal rim are found to increase for a particular position of the crystal radiation reflector.

  10. Aggregation performance of CdO grains grown on surface of N silicon crystal

    International Nuclear Information System (INIS)

    Zhang Jizhong; Zhao Huan

    2010-01-01

    Four kinds of aggregation patterns of CdO grains were formed on the surface of N silicon substrate heated at 580 deg. C for 1 h in an evaporation-deposition device. They were ellipse-shaped or quasi-circular-shaped aggregate, long ribbon-shaped aggregate, long chain-shaped or long double-chain-shaped aggregate, and long ellipse-chain-shaped aggregate. These aggregates consisted of numerous grains or tiny crystals, and deposited on top of the CdO bush-like long crystal clusters grown earlier. They exhibited clearly spontaneous self-organization aggregation performance. Surface defects of the virgin N silicon crystal were analyzed, and mechanism of the self-organization aggregation was discussed with a defect induced aggregation (DIA) model.

  11. Numerical investigation of magnetic field effect on pressure in cylindrical and hemispherical silicon CZ crystal growth

    International Nuclear Information System (INIS)

    Mokhtari, F.; Bouabdallah, A.; Merah, A.; Oualli, H.

    2012-01-01

    The effect of axial magnetic field of different intensities on pressure in silicon Czochralski crystal growth is investigated in cylindrical and hemispherical geometries with rotating crystal and crucible and thermocapillary convection. As one important thermodynamic variable, the pressure is found to be more sensitive than temperature to magnetic field with strong dependence upon the vorticity field. The pressure at the triple point is proposed as a convenient parameter to control the homogeneity of the grown crystal. With a gradual increase of the magnetic field intensity the convection effect can be reduced without thermal fluctuations in the silicon melt. An evaluation of the magnetic interaction parameter critical value corresponding to flow, pressure and temperature homogenization leads to the important result that a relatively low axial magnetic field is required for the spherical system comparatively to the cylindrical one. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Numerical investigation of magnetic field effect on pressure in cylindrical and hemispherical silicon CZ crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, F. [Universite Mouloud Mammeri de Tizi Ouzou (Algeria); LTSE Laboratory, University of Science and Technology. BP 32 Elalia, Babezzouar, Algiers (Algeria); Bouabdallah, A. [LTSE Laboratory, University of Science and Technology. BP 32 Elalia, Babezzouar, Algiers (Algeria); Merah, A. [LTSE Laboratory, University of Science and Technology. BP 32 Elalia, Babezzouar, Algiers (Algeria); M' hamed Bougara University, Boumerdes (Algeria); Oualli, H. [EMP, Bordj ElBahri, Algiers (Algeria)

    2012-12-15

    The effect of axial magnetic field of different intensities on pressure in silicon Czochralski crystal growth is investigated in cylindrical and hemispherical geometries with rotating crystal and crucible and thermocapillary convection. As one important thermodynamic variable, the pressure is found to be more sensitive than temperature to magnetic field with strong dependence upon the vorticity field. The pressure at the triple point is proposed as a convenient parameter to control the homogeneity of the grown crystal. With a gradual increase of the magnetic field intensity the convection effect can be reduced without thermal fluctuations in the silicon melt. An evaluation of the magnetic interaction parameter critical value corresponding to flow, pressure and temperature homogenization leads to the important result that a relatively low axial magnetic field is required for the spherical system comparatively to the cylindrical one. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Sensitivity of triple-crystal X-ray diffractometers to microdefects in silicon

    International Nuclear Information System (INIS)

    Molodkin, V.B.; Olikhovskii, S.I.; Len, E.G.; Kislovskii, E.N.; Kladko, V.P.; Reshetnyk, O.V.; Vladimirova, T.P.; Sheludchenko, B.V.

    2009-01-01

    The dynamical theory, which describes both diffraction profiles and reciprocal space maps measured from imperfect crystals with account for instrumental factors of triple-crystal diffractometer (TCD), has been developed for adequate quantitative characterization of microdefects. Analytical expressions for coherent and diffuse scattering (DS) intensities measured by TCD in the Bragg diffraction geometry have been derived by using the generalized statistical dynamical theory of X-ray scattering in real single crystals with randomly distributed defects. The DS intensity distributions from single crystals containing clusters and dislocation loops have been described by explicit analytical expressions. Particularly, these expressions take into account anisotropy of displacement fields around defects with discrete orientations. Characteristics of microdefect structures in silicon single crystals grown by Czochralsky- and float-zone methods have been determined by analyzing the measured TCD profiles and reciprocal space maps. The sensitivities of reciprocal space maps and diffraction profiles to defect characteristics have been compared. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  14. Laser induced single-crystal transition in polycrystalline silicon

    International Nuclear Information System (INIS)

    Vitali, G.; Bertolotti, M.; Foti, G.; Rimini, E.

    1978-01-01

    Transition to single crystal of polycrystalline Si material underlying a Si crystal substrate of 100 orientation was obtained via laser irradiation. The changes in the structure were analyzed by reflection high energy electron diffraction and by channeling effect technique using 2.0 MeV He Rutherford scattering. The power density required to induce the transition in a 4500 A thick polycrystalline layer is about 70 MW/cm 2 (50ns). The corresponding amorphous to single transition has a threshold of about 45 MW/cm 2 . (orig.) 891 HPOE [de

  15. Single-crystal silicon trench etching for fabrication of highly integrated circuits

    Science.gov (United States)

    Engelhardt, Manfred

    1991-03-01

    The development of single crystal silicon trench etching for fabrication of memory cells in 4 16 and 64Mbit DRAMs is reviewed in this paper. A variety of both etch tools and process gases used for the process development is discussed since both equipment and etch chemistry had to be improved and changed respectively to meet the increasing requirements for high fidelity pattern transfer with increasing degree of integration. In additon to DRAM cell structures etch results for deep trench isolation in advanced bipolar ICs and ASICs are presented for these applications grooves were etched into silicon through a highly doped buried layer and at the borderline of adjacent p- and n-well areas respectively. Shallow trench etching of large and small exposed areas with identical etch rates is presented as an approach to replace standard LOCOS isolation by an advanced isolation technique. The etch profiles were investigated with SEM TEM and AES to get information on contathination and damage levels and on the mechanism leading to anisotropy in the dry etch process. Thermal wave measurements were performed on processed single crystal silicon substrates for a fast evaluation of the process with respect to plasma-induced substrate degradation. This useful technique allows an optimization ofthe etch process regarding high electrical performance of the fully processed memory chip. The benefits of the use of magnetic fields for the development of innovative single crystal silicon dry

  16. Progress in thin-film silicon solar cells based on photonic-crystal structures

    Science.gov (United States)

    Ishizaki, Kenji; De Zoysa, Menaka; Tanaka, Yoshinori; Jeon, Seung-Woo; Noda, Susumu

    2018-06-01

    We review the recent progress in thin-film silicon solar cells with photonic crystals, where absorption enhancement is achieved by using large-area resonant effects in photonic crystals. First, a definitive guideline for enhancing light absorption in a wide wavelength range (600–1100 nm) is introduced, showing that the formation of multiple band edges utilizing higher-order modes confined in the thickness direction and the introduction of photonic superlattice structures enable significant absorption enhancement, exceeding that observed for conventional random scatterers. Subsequently, experimental evidence of this enhancement is demonstrated for a variety of thin-film Si solar cells: ∼500-nm-thick ultrathin microcrystalline silicon cells, few-µm-thick microcrystalline silicon cells, and ∼20-µm-thick thin single-crystalline silicon cells. The high short-circuit current densities and/or efficiencies observed for each cell structure confirm the effectiveness of using multiple band-edge resonant modes of photonic crystals for enhancing broadband absorption in actual solar cells.

  17. Phase transformation during silica cluster impact on crystal silicon substrate studied by molecular dynamics simulation

    International Nuclear Information System (INIS)

    Chen Ruling; Luo Jianbin; Guo Dan; Lu Xinchun

    2008-01-01

    The process of a silica cluster impact on a crystal silicon substrate is studied by molecular dynamics simulation. At the impact loading stage, crystal silicon of the impact zone transforms to a locally ordered molten with increasing the local temperature and pressure of the impact zone. And then the transient molten forms amorphous silicon directly as the local temperature and pressure decrease at the impact unloading stage. Moreover, the phase behavior between the locally ordered molten and amorphous silicon exhibits the reversible structural transition. The transient molten contains not only lots of four-fold atom but also many three- and five-fold atoms. And the five-fold atom is similar to the mixture structure of semi-Si-II and semi-bct5-Si. The structure transformation between five- and four-fold atoms is affected by both pressure and temperature. The structure transformation between three- and four-fold atoms is affected mostly by temperature. The direct structure transformation between five- and three-fold atoms is not observed. Finally, these five- and three-fold atoms are also different from the usual five- and three-fold deficient atoms of amorphous silicon. In addition, according to the change of coordination number of atoms the impact process is divided into six stages: elastic, plastic, hysteresis, phase regressive, adhesion and cooling stages

  18. Rare earth concentration in the primary Si crystal in rare earth added Al-21 wt. % Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, J.Y.; Kim, G.H. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); Moon, I.G.; Choi, C.S. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Metallurgical Engineering

    1998-07-03

    Al-Si alloys containing more than about 12 wt. % Si exhibit a hypereutectic microstructure, normally consisting of a primary silicon phase in an eutectic matrix. The primary silicon in normal hypereutectic alloys is usually very coarse and thus leads to poor properties to these alloys. Therefore, alloys with a predominantly coarse primary silicon crystal must be modified to ensure adequate mechanical strength and ductility. Further improvement of mechanical properties of these alloys can be achieved by the modification of eutectic microstructure. Therefore, development of a modifier or refiner that can produce both fine primary and eutectic Si is a major factor which can lead to significant enhancement of mechanical properties in hypereutectic Al-Si alloys. Refinement of primary silicon is usually achieved by the addition of phosphor to the melt. On the other hand, it is reported that the rare earth (RE) elements are capable of modifying the eutectic structure of cast Al-Si alloys. According to the literature, Phosphor acts as a heterogeneous nucleation site of Si crystal by forming AlP intermetallic particles at high temperature, i.e., above liquidus temperature of Al-Si alloy. Unlike phosphor, RE was not known to form a stable compound with Al that can act as a nucleation site at high temperature. Therefore, the role of RE as a refiner should be considered by examining the behavior of RE as a solute in the melt. The distribution of RE within the primary Si and in the matrix of the alloy will provide a clue to the role of RE on the modification of primary Si during solidification.

  19. Primary and secondary fragmentation of crystal-bearing intermediate magma

    Science.gov (United States)

    Jones, Thomas J.; McNamara, Keri; Eychenne, Julia; Rust, Alison C.; Cashman, Katharine V.; Scheu, Bettina; Edwards, Robyn

    2016-11-01

    Crystal-rich intermediate magmas are subjected to both primary and secondary fragmentation processes, each of which may produce texturally distinct tephra. Of particular interest for volcanic hazards is the extent to which each process contributes ash to volcanic plumes. One way to address this question is by fragmenting pyroclasts under controlled conditions. We fragmented pumice samples from Soufriere Hills Volcano (SHV), Montserrat, by three methods: rapid decompression in a shock tube-like apparatus, impact by a falling piston, and milling in a ball mill. Grain size distributions of the products reveal that all three mechanisms produce fractal breakage patterns, and that the fractal dimension increases from a minimum of 2.1 for decompression fragmentation (primary fragmentation) to a maximum of 2.7 by repeated impact (secondary fragmentation). To assess the details of the fragmentation process, we quantified the shape, texture and components of constituent ash particles. Ash shape analysis shows that the axial ratio increases during milling and that particle convexity increases with repeated impacts. We also quantify the extent to which the matrix is separated from the crystals, which shows that secondary processes efficiently remove adhering matrix from crystals, particularly during milling (abrasion). Furthermore, measurements of crystal size distributions before (using x-ray computed tomography) and after (by componentry of individual grain size classes) decompression-driven fragmentation show not only that crystals influence particular size fractions across the total grain size distribution, but also that free crystals are smaller in the fragmented material than in the original pumice clast. Taken together, our results confirm previous work showing both the control of initial texture on the primary fragmentation process and the contributions of secondary processes to ash formation. Critically, however, our extension of previous analyses to characterisation

  20. Crystallization and growth of Ni-Si alloy thin films on inert and on silicon substrates

    Science.gov (United States)

    Grimberg, I.; Weiss, B. Z.

    1995-04-01

    The crystallization kinetics and thermal stability of NiSi2±0.2 alloy thin films coevaporated on two different substrates were studied. The substrates were: silicon single crystal [Si(100)] and thermally oxidized silicon single crystal. In situ resistance measurements, transmission electron microscopy, x-ray diffraction, Auger electron spectroscopy, and Rutherford backscattering spectroscopy were used. The postdeposition microstructure consisted of a mixture of amorphous and crystalline phases. The amorphous phase, independent of the composition, crystallizes homogeneously to NiSi2 at temperatures lower than 200 °C. The activation energy, determined in the range of 1.4-2.54 eV, depends on the type of the substrate and on the composition of the alloyed films. The activation energy for the alloys deposited on the inert substrate was found to be lower than for the alloys deposited on silicon single crystal. The lowest activation energy was obtained for nonstoichiometric NiSi2.2, the highest for NiSi2—on both substrates. The crystallization mode depends on the structure of the as-deposited films, especially the density of the existing crystalline nuclei. Substantial differences were observed in the thermal stability of the NiSi2 compound on both substrates. With the alloy films deposited on the Si substrate, only the NiSi2 phase was identified after annealing to temperatures up to 800 °C. In the films deposited on the inert substrate, NiSi and NiSi2 phases were identified when the Ni content in the alloy exceeded 33 at. %. The effects of composition and the type of substrate on the crystallization kinetics and thermal stability are discussed.

  1. Digital silicon photomultiplier readout of a new fast and bright scintillation crystal (Ce:GFAG)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong-Seok [Department of Bio-convergence Engineering, Korea University, Seoul (Korea, Republic of); Leem, Hyun-Tae [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Yamamoto, Seiichi [Department of Medical Technology, Nagoya University Graduate School of Medicine, Nagoya (Japan); Choi, Yong, E-mail: ychoi@sogang.ac.kr [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Kamada, Kei [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); C& A corporation, Sendai (Japan); Yoshikawa, Akira [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); C& A corporation, Sendai (Japan); Institute for Material Research, Tohoku University, Sendai (Japan); Park, Sang-Geon [Department of Electrical & Electronics, Silla University, Pusan (Korea, Republic of); Yeom, Jung-Yeol, E-mail: jungyeol@korea.ac.kr [Department of Bio-convergence Engineering, Korea University, Seoul (Korea, Republic of); School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of)

    2016-10-01

    A new Gadolinium Fine Aluminum Gallate (Ce:GFAG) scintillation crystal with both high energy resolution and fast timing properties has successfully been grown. Compared to Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (Ce:GAGG), this new inorganic scintillation crystal has a high luminosity similar to and a faster decay time. In this paper, we report on the timing and energy performance results of the new GFAG scintillation crystal read out with digital silicon photomultipliers (dSiPM) for positron emission tomography (PET) application. The best coincidence resolving time (FWHM) of polished 3×3×5 mm{sup 3} crystals was 223±6 ps for GFAG crystals compared to 396±28 ps for GAGG crystals and 131±3 ps for LYSO crystals respectively. An energy resolution (511 keV peak of Na-22) of 10.9±0.2% was attained with GFAG coupled to dSiPM after correcting for saturation effect, compared to 9.5±0.3% for Ce:GAGG crystals and 11.9±0.4% for LYSO crystals respectively. It is expected that this new scintillator may be competitive in terms of overall properties such as energy resolution, timing resolution and growing (raw material) cost, compared to existing scintillators for positron emission tomography (PET).

  2. Boron, phosphorus, and gallium determination in silicon crystals doped with gallium

    International Nuclear Information System (INIS)

    Shklyar, B.L.; Dankovskij, Yu.V.; Trubitsyn, Yu.V.

    1989-01-01

    When studying IR transmission spectra of silicon doped with gallium in the range of concentrations 1 x 10 14 - 5 x 10 16 cm -3 , the possibility to quantity at low (∼ 20 K) temperatures residual impurities of boron and phosphorus is ascertained. The lower determination limit of boron is 1 x 10 12 cm -3 for a sample of 10 nm thick. The level of the impurities in silicon crystals, grown by the Czochralski method and method of crucible-free zone melting, is measured. Values of boron and phosphorus concentrations prior to and after their alloying with gallium are compared

  3. Enhanced four-wave mixing in graphene-silicon slow-light photonic crystal waveguides

    International Nuclear Information System (INIS)

    Zhou, Hao; Gu, Tingyi; McMillan, James F.; Wong, Chee Wei; Petrone, Nicholas; Zande, Arend van der; Hone, James C.; Yu, Mingbin; Lo, Guoqiang; Kwong, Dim-Lee; Feng, Guoying; Zhou, Shouhuan

    2014-01-01

    We demonstrate the enhanced four-wave mixing of monolayer graphene on slow-light silicon photonic crystal waveguides. 200-μm interaction length, a four-wave mixing conversion efficiency of −23 dB is achieved in the graphene-silicon slow-light hybrid, with an enhanced 3-dB conversion bandwidth of about 17 nm. Our measurements match well with nonlinear coupled-mode theory simulations based on the measured waveguide dispersion, and provide an effective way for all-optical signal processing in chip-scale integrated optics.

  4. Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides

    DEFF Research Database (Denmark)

    Yan, Siqi; Zhu, Xiaolong; Frandsen, Lars Hagedorn

    2017-01-01

    Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light-matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally...... in silicon photonics. The corresponding figure of merit of the device is 2.543 nW s, one order of magnitude better than results reported in previous studies. The influence of the length and shape of the graphene heater to the tuning efficiency is further investigated, providing valuable guidelines...

  5. Influence of intermediate layers on the surface condition of laser crystallized silicon thin films and solar cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Höger, Ingmar, E-mail: ingmar.hoeger@ipht-jena.de; Gawlik, Annett; Brückner, Uwe; Andrä, Gudrun [Leibniz-Institut für Photonische Technologien, PF 100239, 07702 Jena (Germany); Himmerlich, Marcel; Krischok, Stefan [Institut für Mikro-und Nanotechnologien, Technische Universität Ilmenau, PF 100565, 98684 Ilmenau (Germany)

    2016-01-28

    The intermediate layer (IL) between glass substrate and silicon plays a significant role in the optimization of multicrystalline liquid phase crystallized silicon thin film solar cells on glass. This study deals with the influence of the IL on the surface condition and the required chemical surface treatment of the crystallized silicon (mc-Si), which is of particular interest for a-Si:H heterojunction thin film solar cells. Two types of IL were investigated: sputtered silicon nitride (SiN) and a layer stack consisting of silicon nitride and silicon oxide (SiN/SiO). X-ray photoelectron spectroscopy measurements revealed the formation of silicon oxynitride (SiO{sub x}N{sub y}) or silicon oxide (SiO{sub 2}) layers at the surface of the mc-Si after liquid phase crystallization on SiN or SiN/SiO, respectively. We propose that SiO{sub x}N{sub y} formation is governed by dissolving nitrogen from the SiN layer in the silicon melt, which segregates at the crystallization front during crystallization. This process is successfully hindered, when additional SiO layers are introduced into the IL. In order to achieve solar cell open circuit voltages above 500 mV, a removal of the formed SiO{sub x}N{sub y} top layer is required using sophisticated cleaning of the crystallized silicon prior to a-Si:H deposition. However, solar cells crystallized on SiN/SiO yield high open circuit voltage even when a simple wet chemical surface treatment is applied. The implementation of SiN/SiO intermediate layers facilitates the production of mesa type solar cells with open circuit voltages above 600 mV and a power conversion efficiency of 10%.

  6. Liquid gallium cooling of silicon crystals in high intensity photon beams

    International Nuclear Information System (INIS)

    Smither, R.K.; Forster, G.A.; Bilderback, D.H.; Bedzyk, M.; Finkelstein, K.; Henderson, C.; White, J.; Berman, L.E.; Stefan, P.; Oversluizen, T.

    1989-01-01

    The high-brilliance, insertion-device-based photon beams of the next generation of synchrotron sources (Argonne's APS and Grenoble's ESRF) will deliver large thermal loads (1--10 kW) to the first optical elements. Considering the problems that present synchrotron users are experiencing with beams from recently installed insertion devices, new and improved methods of cooling these first optical elements, particularly when they are diffraction crystals, are clearly needed. A series of finite element calculations were performed to test the efficiency of new cooling geometries and various cooling fluids. The best results were obtained with liquid Ga metal flowing in channels just below the surface of the crystal. Ga was selected because of its good thermal conductivity and thermal capacity, low melting point, high boiling point, low kinetic viscosity, and very low vapor pressure. Its very low vapor pressure, even at elevated temperatures, makes it especially attractive in UHV conditions. A series of experiments were conducted at CHESS in February of 1988 that compared liquid gallium-cooled silicon diffraction crystals with water-cooled crystals. A six-pole wiggler beam was used to perform these tests on three different Si crystals, two with new cooling geometries and the one presently in use. A special high-pressure electromagnetic induction pump, recently developed at Argonne, was used to circulate the liquid gallium through the silicon crystals. In all experiments, the specially cooled crystal was used as the first crystal in a two crystal monochromator. An infrared camera was used to monitor the thermal profiles and correlated them with rocking curve measurements. A second set of cooling experiments were conducted in June of 1988 that used the intense, highly collimated beam from the newly installed ANL/CHESS undulator

  7. Strontium titanate/silicon-based terahertz photonic crystal multilayer stack

    International Nuclear Information System (INIS)

    Xin, J.Z.; Jim, K.L.; Tsang, Y.H.; Chan, H.L.W.; Leung, C.W.; Yang, J.; Gong, X.J.; Chen, L.Q.; Gao, F.

    2012-01-01

    A one-dimensional photonic crystal working in the terahertz (THz) range was designed and implemented. To facilitate the design, the transmission properties of strontium titanate crystals were characterized by THz-time-domain spectroscopy. Relatively high refractive index (∝18.5) and transmission ratio (0.08) were observed between 0.2 to 1 THz. A stacked structure of (Si d Si /STO d STO ) N /Si d Si was then designed, with transmission spectra calculated by the transfer matrix method. The effects of the filling ratio (d STO /(d Si +d STO )), periodicity (d Si +d STO ) and the number of repeats N on the transmission of PC were investigated. The effect of introducing a defect layer was also studied. Based on these, Si/STO multilayers with STO defect thickness of 125 μm and 200 μm were measured. The shift of the defect mode was observed and compared with the calculations. (orig.)

  8. Silicon nano crystal-based non-volatile memory devices

    International Nuclear Information System (INIS)

    Ng, C.Y.; Chen, T.P.; Sreeduth, D.; Chen, Q.; Ding, L.; Du, A.

    2006-01-01

    In this work, we have investigated the performance and reliability of a Flash memory based on silicon nanocrystal synthesized with very-low energy ion beams. The devices are fabricated with a conventional CMOS process and the size of the nanocrystal is ∼ 4 nm as determined from TEM measurement. Electrical properties of the devices with a tunnel oxide of either 3 nm or 7 nm are evaluated. The devices exhibit good endurance up to 10 5 W/E cycles even at the high operation temperature of 85 deg. C for both the tunnel oxide thicknesses. For the thicker tunnel oxide (i.e., the 7-nm tunnel oxide), a good retention performance with an extrapolated 10-year memory window of ∼ 0.3 V (or ∼ 20% of charge lose after 10 years) is achieved. However, ∼ 70% of charge loss after 10 years is expected for the thinner tunnel oxide (i.e., the 3-nm tunnel oxide)

  9. A thermal model for czochralski silicon crystal growth with an axial magnetic field

    Science.gov (United States)

    Hjellming, L. N.

    1990-07-01

    This paper presents a thermal model for molten silicon in a Czochralski crystal puller system with an applied uniform axial magnetic field. The melt depth is treated as continually decreasing, which affects the thermal environment of the melt and crystal. The radiative heat loss and the input heat flux are treated as functions of time, with a constraint placed on the heat lost to the crystal from the melt. As the melt motion reaches a steady state rapidly, the temperature and flow fields are treated as instantaneously steady at each melt depth. The heat transport is a mixture of conduction and convection, and by considering the crystal and crucible to be rotating with the same angular velocity, the flows driven by buoyancy and thermocapillarity are isolated and provide the convective heat transport in the melt for the range of magnetic field strengths 0.2 ≤ B ≤ 1.0T.

  10. Fabrication of triangular nanobeam waveguide networks in bulk diamond using single-crystal silicon hard masks

    International Nuclear Information System (INIS)

    Bayn, I.; Mouradian, S.; Li, L.; Goldstein, J. A.; Schröder, T.; Zheng, J.; Chen, E. H.; Gaathon, O.; Englund, Dirk; Lu, M.; Stein, A.; Ruggiero, C. A.; Salzman, J.; Kalish, R.

    2014-01-01

    A scalable approach for integrated photonic networks in single-crystal diamond using triangular etching of bulk samples is presented. We describe designs of high quality factor (Q = 2.51 × 10 6 ) photonic crystal cavities with low mode volume (V m  = 1.062 × (λ/n) 3 ), which are connected via waveguides supported by suspension structures with predicted transmission loss of only 0.05 dB. We demonstrate the fabrication of these structures using transferred single-crystal silicon hard masks and angular dry etching, yielding photonic crystal cavities in the visible spectrum with measured quality factors in excess of Q = 3 × 10 3

  11. Electro-optical modulator in a polymerinfiltrated silicon slotted photonic crystal waveguide heterostructure resonator.

    Science.gov (United States)

    Wülbern, Jan Hendrik; Petrov, Alexander; Eich, Manfred

    2009-01-05

    We present a novel concept of a compact, ultra fast electro-optic modulator, based on photonic crystal resonator structures that can be realized in two dimensional photonic crystal slabs of silicon as core material employing a nonlinear optical polymer as infiltration and cladding material. The novel concept is to combine a photonic crystal heterostructure cavity with a slotted defect waveguide. The photonic crystal lattice can be used as a distributed electrode for the application of a modulation signal. An electrical contact is hence provided while the optical wave is kept isolated from the lossy metal electrodes. Thereby, well known disadvantages of segmented electrode designs such as excessive scattering are avoided. The optical field enhancement in the slotted region increases the nonlinear interaction with an external electric field resulting in an envisaged switching voltage of approximately 1 V at modulation speeds up to 100 GHz.

  12. Photoluminescence at room temperature of liquid-phase crystallized silicon on glass

    Directory of Open Access Journals (Sweden)

    Michael Vetter

    2016-12-01

    Full Text Available The room temperature photoluminescence (PL spectrum due band-to-band recombination in an only 8 μm thick liquid-phase crystallized silicon on glass solar cell absorber is measured over 3 orders of magnitude with a thin 400 μm thick optical fiber directly coupled to the spectrometer. High PL signal is achieved by the possibility to capture the PL spectrum very near to the silicon surface. The spectra measured within microcrystals of the absorber present the same features as spectra of crystalline silicon wafers without showing defect luminescence indicating the high electronic material quality of the liquid-phase multi-crystalline layer after hydrogen plasma treatment.

  13. Specific features of doping with antimony during the ion-beam crystallization of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Pashchenko, A. S., E-mail: as.pashchenko@gmail.com; Chebotarev, S. N.; Lunin, L. S. [Russian Academy of Sciences, Southern Scientific Center (Russian Federation); Irkha, V. A. [Special Engineering and Technology Department “Inversiya” Ltd. (Russian Federation)

    2016-04-15

    A method of doping during the growth of thin films by ion-beam crystallization is proposed. By the example of Si and Sb, the possibility of controllably doping semiconductors during the ion-beam crystallization process is shown. A calibrated temperature dependence of the antimony vapor flow rate in the range from 150 to 400°C is obtained. It is established that, an increase in the evaporator temperature above 200°C brings about the accumulation of impurities in the layer growth direction. Silicon layers doped with antimony to a concentration of 10{sup 18} cm{sup –3} are grown. It is shown that, as the evaporator temperature is increased, the efficiency of the activation of antimony in silicon nonlinearly decreases from ~10{sup 0} to ~10{sup –3}.

  14. Visualization of nanosecond laser-induced dewetting, ablation and crystallization processes in thin silicon films

    Science.gov (United States)

    Qi, Dongfeng; Zhang, Zifeng; Yu, Xiaohan; Zhang, Yawen

    2018-06-01

    In the present work, nanosecond pulsed laser crystallization, dewetting and ablation of thin amorphous silicon films are investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 7 ns temporal width are irradiated on silicon film. Below the dewetting threshold, crystallization process happens after 400 ns laser irradiation in the spot central region. With the increasing of laser fluence, it is observed that the dewetting process does not conclude until 300 ns after the laser irradiation, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to solidification of transported matter at about 500 ns following the laser pulse exposure.

  15. Amorphous Silicon-Germanium Films with Embedded Nano crystals for Thermal Detectors with Very High Sensitivity

    International Nuclear Information System (INIS)

    Calleja, C.; Torres, A.; Rosales-Quintero, P.; Moreno, M.

    2016-01-01

    We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nano crystals in a plasma enhanced chemical vapor deposition (PECVD) reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR), which is a signature of the sensitivity in thermal detectors (micro bolometers). Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9%K -1 ). Our results show that amorphous silicon-germanium films with embedded nano crystals can be used as thermo sensitive films in high performance infrared focal plane arrays (IRFPAs) used in commercial thermal cameras.

  16. High-voltage electron-microscopical observation of crack-tip dislocations in silicon crystals

    International Nuclear Information System (INIS)

    Tanaka, Masaki; Higashida, Kenji

    2005-01-01

    Crack-tip dislocations in silicon single crystals were observed by high-voltage electron microscopy. Cracks were introduced into silicon wafers at room temperature by a Vickers indenter. The indented specimens were annealed at 823 K in order to activate dislocation emission from the crack tip under the residual stress due to the indentation. In the specimen without annealing, no dislocations were observed around the crack. On the other hand, in the specimen after the annealing, the aspect of the early stage of dislocation emission was observed, where dislocations were emitted not as a perfect dislocation but as a partial dislocation in the hinge-type plastic zone. Prominent dislocation arrays that were emitted from a crack tip were also observed, and they were found to be of shielding type, which increases the fracture toughness of those crystals

  17. Selective tuning of high-Q silicon photonic crystal nanocavities via laser-assisted local oxidation.

    Science.gov (United States)

    Chen, Charlton J; Zheng, Jiangjun; Gu, Tingyi; McMillan, James F; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee; Wong, Chee Wei

    2011-06-20

    We examine the cavity resonance tuning of high-Q silicon photonic crystal heterostructures by localized laser-assisted thermal oxidation using a 532 nm continuous wave laser focused to a 2.5 μm radius spot-size. The total shift is consistent with the parabolic rate law. A tuning range of up to 8.7 nm is achieved with ∼ 30 mW laser powers. Over this tuning range, the cavity Qs decreases from 3.2×10(5) to 1.2×10(5). Numerical simulations model the temperature distributions in the silicon photonic crystal membrane and the cavity resonance shift from oxidation.

  18. Extraordinary Light-Trapping Enhancement in Silicon Solar Cell Patterned with Graded Photonic Super-Crystals

    Directory of Open Access Journals (Sweden)

    Safaa Hassan

    2017-12-01

    Full Text Available Light-trapping enhancement in newly discovered graded photonic super-crystals (GPSCs with dual periodicity and dual basis is herein explored for the first time. Broadband, wide-incident-angle, and polarization-independent light-trapping enhancement was achieved in silicon solar cells patterned with these GPSCs. These super-crystals were designed by multi-beam interference, rendering them flexible and efficient. The optical response of the patterned silicon solar cell retained Bloch-mode resonance; however, light absorption was greatly enhanced in broadband wavelengths due to the graded, complex unit super-cell nanostructures, leading to the overlap of Bloch-mode resonances. The broadband, wide-angle light coupling and trapping enhancement mechanism are understood to be due to the spatial variance of the index of refraction, and this spatial variance is due to the varying filling fraction, the dual basis, and the varying lattice constants in different directions.

  19. Soft component of channeled electron radiation in silicon crystals

    International Nuclear Information System (INIS)

    Vnukov, I.E.; Kalinin, B.N.; Kiryakov, A.A.; Naumenko, G.A.; Padalko, D.V.; Potylitsyn, A.P.

    2001-01-01

    Radiation spectrum and orientation dependences of photon yield with the energy much lower than characteristic radiation energy during channeling were measured using a crystal-diffraction spectrometer. For electron drop along axis radiation intensity in the spectral range 30 ≤ ω ≤ 360 keV exceeds by nearly an order the intensity of Bremsstrahlung. The shape of radiation spectrum does not coincide with Bremsstrahlung spectrum. Radiation intensity increases gradually with photons energy growth. Bremsstrahlung spectrum from a disoriented crystalline target is described in a satisfactory manner by the currently used theory with phenomenological account of the medium polarization [ru

  20. Visual Sensor for Sterilization of Polymer Fixtures Using Embedded Mesoporous Silicon Photonic Crystals.

    Science.gov (United States)

    Kumeria, Tushar; Wang, Joanna; Chan, Nicole; Harris, Todd J; Sailor, Michael J

    2018-01-26

    A porous photonic crystal is integrated with a plastic medical fixture (IV connector hub) to provide a visual colorimetric sensor to indicate the presence or absence of alcohol used to sterilize the fixture. The photonic crystal is prepared in porous silicon (pSi) by electrochemical anodization of single crystal silicon, and the porosity and the stop band of the material is engineered such that the integrated device visibly changes color (green to red or blue to green) when infiltrated with alcohol. Two types of self-reporting devices are prepared and their performance compared: the first type involves heat-assisted fusion of a freestanding pSi photonic crystal to the connector end of a preformed polycarbonate hub, forming a composite where the unfilled portion of the pSi film acts as the sensor; the second involves generation of an all-polymer replica of the pSi photonic crystal by complete thermal infiltration of the pSi film and subsequent chemical dissolution of the pSi portion. Both types of sensors visibly change color when wetted with alcohol, and the color reverts to the original upon evaporation of the liquid. The sensor performance is verified using E. coli-infected samples.

  1. Observation of Multiple Volume Reflection of Ultrarelativistic Protons by a Sequence of Several Bent Silicon Crystals

    CERN Document Server

    Scandale, Walter; Baricordi, S; Dalpiaz, P; Fiorini, M; Guidi, V; Mazzolari, A; Della Mea, G; Milan, R; Ambrosi, G; Zuccon, P; Bertucci, B; Bürger, W; Duranti, M; Cavoto, G; Santacesaria, R; Valente, P; Luci, C; Iacoangeli, F; Vallazza, E; Afonin, A G; Chesnokov, Yu A; Kotov, V I; Maisheev, V A; Yazynin, I A; Kovalenko, A D; Taratin, A M; Denisov, A S; Gavrikov, Y A; Ivanov, Yu M; Lapina, L P; Malyarenko, L G; Skorogobogatov, V V; Suvorov, V M; Vavilov, S A; Bolognini, D; Hasan, S; Mozzanica, A; Prest, M

    2009-01-01

    The interactions of 400 GeV protons with different sequences of bent silicon crystals have been investigated at the H8 beam line of the CERN Super Proton Synchrotron. The multiple volume reflection of the proton beam has been studied in detail on a five-crystal reflector measuring an angular beam deflection =52.96±0.14 µrad. The efficiency was found larger than 80% for an angular acceptance at the reflector entrance of 70 µrad, with a maximal efficiency value of =0.90±0.01±0.03.

  2. High-Efficiency Volume Reflection of an Ultrarelativistic Proton Beam with a Bent Silicon Crystal

    CERN Document Server

    Scandale, Walter; Carnera, Alberto; Della Mea, Gianantonio; De Salvador, Davide; Milan, Riccardo; Vomiero, Alberto; Baricordi, Stefano; Dalpiaz, Pietro; Fiorini, Massimiliano; Guidi, Vincenzo; Martinelli,Giuliano; Mazzolari, Andrea; Milan, Emiliano; Ambrosi, Giovanni; Azzarello, Philipp; Battiston, Roberto; Bertucci, Bruna; Burger, William J; Ionica, Maria; Zuccon, Paolo; Cavoto, Gianluca; Santacesaria, Roberta; Valente, Paolo; Vallazza, Erik; Afonin, Alexander G; Baranov, Vladimir T; Chesnokov, Yury A; Kotov, Vladilen I; Maisheev, Vladimir A; Yaznin, Igor A; Afansiev, Sergey V; Kovalenko, Alexander D; Taratin, Alexander M; Denisov, Alexander S; Gavrikov, Yury A; Ivanov, Yuri M; Ivochkin, Vladimir G; Kosyanenko, Sergey V; Petrunin, Anatoli A; Skorobogatov, Vyacheslav V; Suvorov, Vsevolod M; Bolognini, Davide; Foggetta,Luca; Hasan, Said; Prest, Michela

    2007-01-01

    The volume reflection phenomenon was detected while investigating 400 GeV proton interactions with bent silicon crystals in the external beam H8 of the CERN Super Proton Synchrotron. Such a process was observed for a wide interval of crystal orientations relative to the beam axis, and its efficiency exceeds 95%, thereby surpassing any previously observed value. These observations suggest new perspectives for the manipulation of high-energy beams, e.g., for collimation and extraction in new-generation hadron colliders, such as the CERN Large Hadron Collider.

  3. Deflection of high energy channeled charged particles by elastically bent silicon single crystals

    International Nuclear Information System (INIS)

    Gibson, W.M.; Kim, I.J.; Pisharodoy, M.; Salman, S.M.; Sun, C.R.; Wang, G.H.; Wijayawardana, R.; Forster, J.S.; Mitchell, I.V.; Baker, S.I.; Carrigan, R.A. Jr.; Toohig, T.E.; Avdeichikov, V.V.; Ellison, J.A.; Siffert, P.

    1984-01-01

    An experiment has been carried out to observe the deflection of charged particles by planar channeling in bent single crystals of silicon for protons with energy up to 180 GeV. Anomolous loss of particles from the center point of a three point bending apparatus was observed at high incident particle energy. This effect has been exploited to fashion a 'dechanneling spectrometer' to study dechanneling effects due to centripital displacement of channeled particle trajectories in a bent crystal. The bending losses generally conform to the predictions of calculations based on a classical model. (orig.)

  4. Defects in Czochralski-grown silicon crystals investigated by positron annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Ikari, Atsushi; Kawakami, Kazuto; Haga, Hiroyo [Nippon Steel Corp., Sagamihara, Kanagawa (Japan). Electronics Research Labs.; Uedono, Akira; Wei, Long; Kawano, Takao; Tanigawa, Shoichiro

    1994-10-01

    Positron lifetime and Doppler broadening experiments were performed on Czochralski-grown silicon crystals. A monoenergetic positron beam was also used to measure the diffusion length of positrons in the wafer. From the measurements, it was observed that the value of diffusion length of positrons decreased at the region where microdefects were formed during the crystal growth process. It was also found that the line shape parameter S decreased and the lifetime of positrons increased at the region. These results can be attributed to the annihilation of positrons trapped by vacancy oxygen complexes which are formed in association with the microdefects. (author).

  5. CO2 laser-induced directional recrystallization to produce single crystal silicon-core optical fibers with low loss

    OpenAIRE

    Healy, Noel; Fokine, Michael; Franz, Yohann; Hawkins, Thomas; Jones, Maxwell; Ballato, John; Peacock, Anna C.; Gibson, Ursula J.

    2016-01-01

    Reduced losses in silicon-core fibers are obtained using CO2 laser directional recrystallization of the core. Single crystals with aspect ratios up to 1500:1 are reported, limited by the scan range of the equipment. This processing technique holds promise for bringing crystalline silicon-core fibers to a central role in nonlinear optics and signal processing applications.

  6. Using short silicon crystals for beam extraction and collimation at U-70 proton synchrotron

    International Nuclear Information System (INIS)

    Afonin, A.G.; Baranov, V.T.; Biryukov, V.M.; Kotov, V.I.; Maisheev, V.A.; Terekhov, V.I.; Troyanov, E.F.; Fedotov, Yu.S.; Chepegin, V.N.; Chesnonkov, Yu.A.

    2002-01-01

    Results of investigations into escape and collimation of proton beams at the IHEP U-70 synchrotron with the application of short flexed silicon monocrystals in length 2 - 4 mm are demonstrated. Good agreement between the measured and calculated efficiency of the flexed crystal is available. Lowering efficiency with the decreasing proton energy is explained by growth of root-mean-square angle of the multiple Coulomb scattering and drop of dechanneling length [ru

  7. Silicon nanocrystal-based photonic crystal slabs with broadband and efficient directional light emission

    Czech Academy of Sciences Publication Activity Database

    Ondič, Lukáš; Varga, Marián; Pelant, Ivan; Valenta, J.; Kromka, Alexander; Elliman, R. G.

    2017-01-01

    Roč. 7, č. 1 (2017), s. 1-8, č. článku 5763. ISSN 2045-2322 R&D Projects: GA ČR GJ16-09692Y; GA MŠk(CZ) LD15003 Institutional support: RVO:68378271 Keywords : photonic crystal slab * silicon nanocrystals * light emission Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.259, year: 2016

  8. Strontium titanate/silicon-based terahertz photonic crystal multilayer stack

    Energy Technology Data Exchange (ETDEWEB)

    Xin, J.Z.; Jim, K.L.; Tsang, Y.H.; Chan, H.L.W.; Leung, C.W. [Hong Kong Polytechnic University, Department of Applied Physics and Materials Research Centre, Kowloon, Hong Kong (China); Yang, J.; Gong, X.J.; Chen, L.Q.; Gao, F. [Chinese Academy of Sciences, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Shenzhen (China)

    2012-04-15

    A one-dimensional photonic crystal working in the terahertz (THz) range was designed and implemented. To facilitate the design, the transmission properties of strontium titanate crystals were characterized by THz-time-domain spectroscopy. Relatively high refractive index ({proportional_to}18.5) and transmission ratio (0.08) were observed between 0.2 to 1 THz. A stacked structure of (Si d{sub Si}/STO d{sub STO}){sub N} /Si d{sub Si} was then designed, with transmission spectra calculated by the transfer matrix method. The effects of the filling ratio (d{sub STO}/(d{sub Si}+d{sub STO})), periodicity (d{sub Si}+d{sub STO}) and the number of repeats N on the transmission of PC were investigated. The effect of introducing a defect layer was also studied. Based on these, Si/STO multilayers with STO defect thickness of 125 {mu}m and 200 {mu}m were measured. The shift of the defect mode was observed and compared with the calculations. (orig.)

  9. Effects of growth conditions on thermal profiles during Czochralski silicon crystal growth

    Science.gov (United States)

    Choe, Kwang Su; Stefani, Jerry A.; Dettling, Theodore B.; Tien, John K.; Wallace, John P.

    1991-01-01

    An eddy current testing method was used to continuously monitor crystal growth process and investigate the effects of growth conditions on thermal profiles during Czochralski silicon crystal growth. The experimental concept was to monitor the intrinsic electrical conductivities of the growing crystal and deduce temperature values from them. In terms of the experiments, the effects of changes in growth parameters, which include the crystal and crucible rotation rates, crucible position, and pull rate, and hot-zone geometries were investigated. The results show that the crystal thermal profile could shift significantly as a function of crystal length if the closed-loop control fails to maintain a constant thermal condition. As a direct evidence to the effects of the melt flow on heat transfer processes, a thermal gradient minimum was observed when the crystal/crucible rotation combination was 20/-10 rpm cw. The thermal gradients in the crystal near the growth interface were reduced most by decreasing the pull rate or by reducing the radiant heat loss to the environment; a nearly constant axial thermal gradient was achieved when either the pull rate was decreased by half, the height of the exposed crucible wall was doubled, or a radiation shield was placed around the crystal. Under these conditions, the average axial thermal gradient along the surface of the crystal was about 4-5°C/mm. When compared to theoretical results found in literature, the axial profiles correlated well with the results of the models which included radiant interactions. However, the radial gradients estimated from three-frequency data were much higher than what were predicted by known theoretical models. This discrepancy seems to indicate that optical phenomenon within the crystal is significant and should be included in theoretical modeling.

  10. Characterization studies of Silicon Photomultipliers and crystals matrices for a novel time of flight PET detector

    CERN Document Server

    Auffray, Etiennette; Cortinovis, Daniele; Doroud, Katayoun; Garutti, Erika; Lecoq, Paul; Liu, Zheng; Martinez, Rosana; Paganoni, Marco; Pizzichemi, Marco; Silenzi, Alessandro; Xu, Chen; Zvolský, Milan

    2015-01-01

    This paper describes the characterization of crystal matrices and silicon photomultiplier arrays for a novel Positron Emission Tomography (PET) detector, namely the external plate of the EndoTOFPET-US system. The EndoTOFPET-US collaboration aims to integrate Time-Of-Flight PET with ultrasound endoscopy in a novel multimodal device, capable to support the development of new biomarkers for prostate and pancreatic tumors. The detector consists in two parts: a PET head mounted on an ultrasound probe and an external PET plate. The challenging goal of 1 mm spatial resolution for the PET image requires a detector with small crystal size, and therefore high channel density: 4096 LYSO crystals individually readout by Silicon Photomultipliers (SiPM) make up the external plate. The quality and properties of these components must be assessed before the assembly. The dark count rate, gain, breakdown voltage and correlated noise of the SiPMs are measured, while the LYSO crystals are evaluated in terms of light yield and en...

  11. Fabrication of polycrystalline silicon thin films on glass substrates using fiber laser crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Dao, Vinh Ai; Han, Kuymin; Heo, Jongkyu; Kyeong, Dohyeon; Kim, Jaehong; Lee, Youngseok; Kim, Yongkuk; Jung, Sungwook; Kim, Kyunghae [Information and Communication Device Laboratory, School of Information and Communication Engineering, Sungkyunkwan University (Korea, Republic of); Yi, Junsin, E-mail: yi@yurim.skku.ac.k [Information and Communication Device Laboratory, School of Information and Communication Engineering, Sungkyunkwan University (Korea, Republic of)

    2009-05-29

    Laser crystallization of amorphous silicon (a-Si), using a fiber laser of {lambda} = 1064 nm wavelength, was investigated. a-Si films with 50 nm thickness deposited on glass were prepared by a plasma enhanced chemical vapor deposition. The infrared fundamental wave ({lambda} = 1064 nm) is not absorbed by amorphous silicon (a-Si) films. Thus, different types of capping layers (a-CeO{sub x}, a-SiN{sub x}, and a-SiO{sub x}) with a desired refractive index, n and thickness, d were deposited on the a-Si surface. Crystallization was a function of laser energy density, and was performed using a fiber laser. The structural properties of the crystallized films were measured via Raman spectra, a scanning electron microscope (SEM), and an atomic force microscope (AFM). The relationship between film transmittance and crystallinity was discussed. As the laser energy density increased from 10-40 W, crystallinity increased from 0-90%. However, the higher laser density adversely affected surface roughness and uniformity of the grain size. We found that favorable crystallization and uniformity could be accomplished at the lower energy density of 30 W with a-SiO{sub x} as the capping layer.

  12. A hybrid model of primary radiation damage in crystals

    International Nuclear Information System (INIS)

    Samarin, S.I.; Dremov, V.V.

    2009-01-01

    The paper offers a hybrid model which combines molecular dynamics and Monte Carlo (MD+MC) methods to describe primary radiation damage in crystals, caused by particles whose energies are no higher than several tens of keV. The particles are tracked in accord with equations of motion with account for pair interaction. The model also considers particle interaction with the mean-field potential (MFP) of the crystal. Only particles involved in cascading are tracked. Equations of motion for these particles include dissipative forces which describe energy exchange between cascade particles and electrons. New particles - the atoms of the crystal in the cascade region - have stochastic parameters (phase coordinates); they are sampled by the Monte Carlo method from the distribution that describes the classic canonical ensemble of non-interacting particles subjected to the external MFP. The introduction of particle interaction with the MFP helps avoid difficulties related to crystal stability and the choice of an adequate interparticle interaction potential in the traditional MD methods. Our technique is many times as fast as the traditional MD methods because we consider only particles which are involved in cascading and apply special methods to speedup the calculation of forces by accounting for the short-range pair potential used

  13. Characterisation and stabilisation of the surface region of a highly polished silicon crystal sphere

    International Nuclear Information System (INIS)

    Kenny, M.J.; Wielunski, L.S.

    1999-01-01

    Full text: Typically a single crystal silicon wafer has a native oxide layer a few nm thick which changes slowly with time. A number of parameters such as hydrocarbons, water vapour, storage environment can affect this layer. The thickness of the layer is also orientation dependent. In the case of a silicon sphere the situation becomes more complex, because all orientations are present and the process of polishing involves a higher pressure and also high local temperatures. A highly polished single crystal sphere 93.6 mm in diameter is being used to determine the Avogadro constant with an uncertainty of ≤ 1 x 10 -8 . This will then be used to obtain an atomic definition of the kilogram. The composition and structure of the surface oxide layer play an important role in this measurement. Firstly the density of the oxide layer is different from that of silicon. Secondly since the diameter is measured by optical interferometry, corrections must be applied for the phase change in the reflected light beam due to the surface layer. Thirdly the orientation dependence of the layer complicated the corrections to be applied. Fourthly if measurements are made over a period of time, any changes in the surface layer must be taken into account. Given the accuracy required in the determination, the surface layer is a determining factor in the final result. A number of techniques such as spectroscopic ellipsometry and ion beam analysis are being used to study the composition and structure of the surface of a silicon sphere. Cleaning techniques such as HF and low temperature ultraviolet (ozone) are being developed to produce a clean surface. The next step involves deposition of a stable and uniform surface oxide layer a few nm thick. Techniques being investigated for this include ultra violet ozone deposition at 450 deg C and plasma deposition. The paper describes work at the NML in achieving an appropriate stable surface on the silicon sphere

  14. Redistribution of erbium during the crystallization of buried amorphous silicon layers

    International Nuclear Information System (INIS)

    Aleksandrov, O.V.; Nikolaev, Yu.A.; Sobolev, N.A.; Sakharov, V.I.; Serenkov, I.T.; Kudryavtsev, Yu.A.

    1999-01-01

    The redistribution of Er during its implantation in silicon at doses close to the amorphization threshold and its subsequent solid-phase epitaxial (SPE) crystallization is investigated. The formation of a buried amorphous (a) layer is discovered at Er doses equal to 5x10 13 and 1x10 14 cm -2 using Rutherford backscattering. The segregation of Er in this case takes place inwardly from the two directions corresponding to the upper and lower boundaries of the buried αlayer and leads to the formation of a concentration peak at the meeting place of the two crystallization fronts. A method for calculating the coordinate dependence of the segregation coefficient k from the distribution profiles of the erbium impurity before and after annealing is proposed. The k(x) curve exhibits a drop, whose width increases with decreasing Er implantation dose. Its appearance is attributed to the nonequilibrium nature of the segregation process at the beginning of SPE crystallization

  15. Influence of metal induced crystallization parameters on the performance of polycrystalline silicon thin film transistors

    International Nuclear Information System (INIS)

    Pereira, L.; Barquinha, P.; Fortunato, E.; Martins, R.

    2005-01-01

    In this work, metal induced crystallization using nickel was employed to obtain polycrystalline silicon by crystallization of amorphous films for thin film transistor applications. The devices were produced through only one lithographic process with a bottom gate configuration using a new gate dielectric consisting of a multi-layer of aluminum oxide/titanium oxide produced by atomic layer deposition. The best results were obtained for TFTs with the active layer of poly-Si crystallized for 20 h at 500 deg. C using a nickel layer of 0.5 nm where the effective mobility is 45.5 cm 2 V -1 s -1 . The threshold voltage, the on/off current ratio and the sub-threshold voltage are, respectively, 11.9 V, 5.55x10 4 and 2.49 V/dec

  16. Thermal detection of single e-h pairs in a biased silicon crystal detector

    Science.gov (United States)

    Romani, R. K.; Brink, P. L.; Cabrera, B.; Cherry, M.; Howarth, T.; Kurinsky, N.; Moffatt, R. A.; Partridge, R.; Ponce, F.; Pyle, M.; Tomada, A.; Yellin, S.; Yen, J. J.; Young, B. A.

    2018-01-01

    We demonstrate that individual electron-hole pairs are resolved in a 1 cm2 by 4 mm thick silicon crystal (0.93 g) operated at ˜35 mK. One side of the detector is patterned with two quasiparticle-trap-assisted electro-thermal-feedback transition edge sensor arrays held near ground potential. The other side contains a bias grid with 20% coverage. Bias potentials up to ±160 V were used in the work reported here. A fiber optic provides 650 nm (1.9 eV) photons that each produce an electron-hole (e- h+) pair in the crystal near the grid. The energy of the drifting charges is measured with a phonon sensor noise σ ˜0.09 e- h+ pair. The observed charge quantization is nearly identical for h+s or e-s transported across the crystal.

  17. In Situ Determination of Thermal Profiles during Czochralski Silicon Crystal Growth by an Eddy Current Technique.

    Science.gov (United States)

    Choe, Kwang Su.

    An eddy current testing method was developed to continuously monitor crystal growth process and determine thermal profiles in situ during Czochralski silicon crystal growth. The work was motivated by the need to improve the quality of the crystal by controlling thermal gradients and annealing history over the growth cycle. The experimental concept is to monitor intrinsic electrical conductivities of the growing crystal and deduce temperature values from them. The experiments were performed in a resistance-heated Czochralski puller with a 203 mm (8 inch) diameter crucible containing 6.5 kg melt. The silicon crystals being grown were about 80 mm in diameter and monitored by an encircling sensor operating at three different test frequencies (86, 53 and 19 kHz). A one-dimensional analytical solution was employed to translate the detected signals into electrical conductivities. In terms of experiments, the effects of changes in growth condition, which is defined by crystal and crucible rotation rates, crucible position, pull rate, and hot-zone configuration, were investigated. Under a given steady-state condition, the thermal profile was usually stable over the entire length of crystal growth. The profile shifted significantly, however, when the crucible rotation rate was kept too high. As a direct evidence to the effects of melt flow on heat transfer process, a thermal gradient minimum was observed about the crystal/crucible rotation combination of 20/-10 rpm cw. The thermal gradient reduction was still most pronounced when the pull rate or the radiant heat loss to the environment was decreased: a nearly flat axial thermal gradient was achieved when either the pull rate was halved or the height of the exposed crucible wall was effectively doubled. Under these conditions, the average axial thermal gradient along the surface of the crystal was about 4-5 ^{rm o}C/mm. Regardless of growth condition, the three-frequency data revealed radial thermal gradients much larger

  18. Surface texture of single-crystal silicon oxidized under a thin V{sub 2}O{sub 5} layer

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, S. E., E-mail: nikitin@mail.ioffe.ru; Verbitskiy, V. N.; Nashchekin, A. V.; Trapeznikova, I. N.; Bobyl, A. V.; Terukova, E. E. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2017-01-15

    The process of surface texturing of single-crystal silicon oxidized under a V{sub 2}O{sub 5} layer is studied. Intense silicon oxidation at the Si–V{sub 2}O{sub 5} interface begins at a temperature of 903 K which is 200 K below than upon silicon thermal oxidation in an oxygen atmosphere. A silicon dioxide layer 30–50 nm thick with SiO{sub 2} inclusions in silicon depth up to 400 nm is formed at the V{sub 2}O{sub 5}–Si interface. The diffusion coefficient of atomic oxygen through the silicon-dioxide layer at 903 K is determined (D ≥ 2 × 10{sup –15} cm{sup 2} s{sup –1}). A model of low-temperature silicon oxidation, based on atomic oxygen diffusion from V{sub 2}O{sub 5} through the SiO{sub 2} layer to silicon, and SiO{sub x} precipitate formation in silicon is proposed. After removing the V{sub 2}O{sub 5} and silicon-dioxide layers, texture is formed on the silicon surface, which intensely scatters light in the wavelength range of 300–550 nm and is important in the texturing of the front and rear surfaces of solar cells.

  19. ANSYS program and re-validation of the thermal analysis of the Cornell silicon crystal

    International Nuclear Information System (INIS)

    Khounsary, A.; Kuzay, T.

    1992-01-01

    Thermal analysis of the Cornell three-channel silicon crystal is carried out using the ANSYS finite element program. Results are in general agreement with those previously obtained using the Transient Heat Transfer, version B (THTB) program. The main thrust of the present study has been to (a) explore the thermal analysis potentials of the ANSYS program in solving thermal hydraulic problems in the APS beamline design, (b) compare the ANSYS results with those obtained by THTB for a specific test crystal, and (c) obtain some cost benchmarks for the ANSYS program. On the basis of a limited number of test runs for the silicon crystal problem, conclusions can be drawn that (a) except for conduction problems with simple boundary conditions the utility of ANSYS for solving a variety of three-dimensional thermal hydraulic problems is at best limited, (b) in comparison with THTB program, ANSYS requires a more detailed modeling (with increasing computation time) for comparably accurate results, and (c) no firm statement regarding the cost factor can be made at this time although the ANSYS program appears to be more expensive than any other code we have used so far

  20. A new series of two-dimensional silicon crystals with versatile electronic properties

    Science.gov (United States)

    Chae, Kisung; Kim, Duck Young; Son, Young-Woo

    2018-04-01

    Silicon (Si) is one of the most extensively studied materials owing to its significance to semiconductor science and technology. While efforts to find a new three-dimensional (3D) Si crystal with unusual properties have made some progress, its two-dimensional (2D) phases have not yet been explored as much. Here, based on a newly developed systematic ab initio materials searching strategy, we report a series of novel 2D Si crystals with unprecedented structural and electronic properties. The new structures exhibit perfectly planar outermost surface layers of a distorted hexagonal network with their thicknesses varying with the atomic arrangement inside. Dramatic changes in electronic properties ranging from semimetal to semiconducting with indirect energy gaps and even to one with direct energy gaps are realized by varying thickness as well as by surface oxidation. Our predicted 2D Si crystals with flat surfaces and tunable electronic properties will shed light on the development of silicon-based 2D electronics technology.

  1. Transverse wave propagation in [ab0] direction of silicon single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Sang Jin; Kim, Hye Jeong; Kwon, Se Ho; Kim, Young H. [Applied Acoustics Lab, Korea Science Academy of KAIST, Busan(Korea, Republic of)

    2015-12-15

    The speed and oscillation directions of elastic waves propagating in the [ab0] direction of a silicon single crystal were obtained by solving Christoffel's equation. It was found that the quasi waves propagate in the off-principal axis, and hence, the directions of the phase and group velocities are not the same. The maximum deviation of the two directions was 7.2 degree angle. Two modes of the pure transverse waves propagate in the [110] direction with different speeds, and hence, two peaks were observed in the pulse echo signal. The amplitude ratio of the two peaks was dependent on the initial oscillating direction of the incident wave. The pure and quasi-transverse waves propagate in the [210] direction, and the oscillation directions of these waves are perpendicular to each other. The skewing angle of the quasi wave was calculated as 7.14 degree angle, and it was measured as 9.76 degree angle. The amplitude decomposition in the [210] direction was similar to that in the [110] direction, since the oscillation directions of these waves are perpendicular to each other. These results offer useful information in measuring the crystal orientation of the silicon single crystal.

  2. N-type polycrystalline silicon films formed on alumina by aluminium induced crystallization and overdoping

    Energy Technology Data Exchange (ETDEWEB)

    Tuezuen, O. [InESS, UMR 7163 CNRS-ULP, 23 rue du Loess, F-67037 Strasbourg (France)], E-mail: Ozge.Tuzun@iness.c-strasbourg.fr; Slaoui, A. [InESS, UMR 7163 CNRS-ULP, 23 rue du Loess, F-67037 Strasbourg (France); Gordon, I. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Focsa, A. [InESS, UMR 7163 CNRS-ULP, 23 rue du Loess, F-67037 Strasbourg (France); Ballutaud, D. [GEMaC-UMR 8635 CNRS, 1 place Aristide Briand, F-92195 Meudon (France); Beaucarne, G.; Poortmans, J. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium)

    2008-08-30

    In this work, we investigated the formation of n-type polysilicon films on alumina substrates by overdoping a p-type silicon layer obtained by aluminium induced crystallization of amorphous silicon (AIC), and subsequent epitaxy. The phosphorus doping of the AIC was carried out by thermal diffusion from a solid source. The structural quality of the n-type Si film was monitored by optical microscope and scanning electron microscope (SEM). The doping efficiency was determined by resistivity measurements and secondary ion mass spectroscopy (SIMS). The sheet resitivity changed from 2700{omega}/sq to 19.6{omega}/sq after thermal diffusion at 950 deg. C for 1h, indicating the overdoping effect. The SIMS profile carried out after the high temperature epitaxy exhibits a two steps phosphorus distribution, indicating the formation of an n{sup +}n structure.

  3. Effects of material non-linearity on the residual stresses in a dendritic silicon crystal ribbon

    Science.gov (United States)

    Ray, Sujit K.; Utku, Senol

    1990-01-01

    Thermal stresses developed in a dendritic silicon crystal ribbon have been shown to cause plastic deformation and residual stresses in the ribbon. This paper presents an implementation of a numerical model proposed for thermoelastoplastic behavior of a material. The model has been used to study the effects of plasticity of silicon on the residual stresses. The material properties required to implement this model are all assumed, and the response of the material to the variations in these assumed parameters of the constitutive law and in the finite element mesh is investigated. The steady state growth process is observed to be periodic with nonzero residual stresses. Numerical difficulties are also encountered in the computer solution process, resulting in sharp jumps and large oscillations in the stress responses.

  4. Computer simulations of X-ray six-beam diffraction in a perfect silicon crystal. I

    Czech Academy of Sciences Publication Activity Database

    Kohn, V.G.; Khikhlukha, Danila

    2016-01-01

    Roč. 72, May (2016), s. 349-356 ISSN 2053-2733 R&D Projects: GA MŠk EF15_008/0000162; GA MŠk ED1.1.00/02.0061 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162; ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061 Institutional support: RVO:68378271 Keywords : X-ray diffraction * silicon crystal * six-beam diffraction * section topography * computer simulations Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 5.725, year: 2016

  5. Optical properties of organic-silicon photonic crystal nanoslot cavity light source

    Directory of Open Access Journals (Sweden)

    Ming-Jay Yang

    2017-03-01

    Full Text Available We theoretically study a dielectric photonic crystal nanoslot cavity immersed in an organic fluid containing near-infrared dyes by means of a full rate equation model including the complete cavity QED effects. Based on the modeling results, we numerically design an organic-silicon cavity light source in which its mode volume, quality factor, and far-field emission pattern are optimized for energy-efficient, high-speed applications. Dye quantum efficiency improved by two orders of magnitude and 3dB modulation bandwidth of a few hundred GHz can be obtained.

  6. Determination of surface recombination velocity and bulk lifetime in detector grade silicon and germanium crystals

    International Nuclear Information System (INIS)

    Derhacobian, N.; Fine, P.; Walton, J.T.; Wong, Y.K.; Rossington, C.S.; Luke, P.N.

    1993-10-01

    Utility of a noncontact photoconductive decay (PCD) technique is demonstrated in measuring bulk lifetime, τ B , and surface recombination velocity, S, in detector grade silicon and germanium crystals. We show that the simple analytical equations which relate the observed effective lifetimes in PCD transients to τ B and S have a limited range of applicability. The noncontact PCD technique is used to determine the effect of several surface treatments on the observed effective lifetimes in Si and Ge. A degradation of the effective lifetime in Si is reported as result of the growth of a thin layer of native oxide at room temperature under atmospheric conditions

  7. Investigations of structural, dielectric and optical properties on silicon ion irradiated glycine monophosphate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kanagasekaran, T. [Department of Physics, Anna University, Chennai 600 025 (India); Department of Physics and Astrophysics, University of Delhi, New Delhi 110 007 (India); Mythili, P. [Department of Physics, Anna University, Chennai 600 025 (India); Bhagavannarayana, G. [Materials Characterization Division, National Physical Laboratory, New Delhi 110012 (India); Kanjilal, D. [Inter University Accelerator Centre, New Delhi 110 067 (India); Gopalakrishnan, R. [Department of Physics, Anna University, Chennai 600 025 (India)], E-mail: krgkrishnan@annauniv.edu

    2009-08-01

    The 50 MeV silicon ion irradiation induced modifications on structural, optical and dielectric properties of solution grown glycine monophosphate (GMP) crystals were studied. The high-resolution X-ray diffraction study shows the unaltered value of integrated intensity on irradiation. The dielectric constant as a function of frequency and temperature was studied. UV-visible studies reveal the decrease in bandgap values on irradiation and presence of F-centers. The fluorescence spectrum shows the existence of some energy levels, which remains unaffected after irradiation. The scanning electron micrographs reveal the defects formed on irradiation.

  8. Wavelength-controlled external-cavity laser with a silicon photonic crystal resonant reflector

    Science.gov (United States)

    Gonzalez-Fernandez, A. A.; Liles, Alexandros A.; Persheyev, Saydulla; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of an alternative design of external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises a polymer (SU8) bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and sidemode suppression ratio of more than 25 dB.

  9. Quantitative study of the transmission of axially channeled protons in thin silicon crystals

    International Nuclear Information System (INIS)

    Rosner, J.S.; Gibson, W.M.; Golovchenko, J.A.; Goland, A.N.; Wegner, H.E.

    1978-01-01

    The azimuthal distributions of protons transmitted through thin silicon single crystals near the axis were measured using a two-dimensional position-sensitive detector. The data are composed of ringlike distributions with strong azimuthal and transverse energy dependence. The azimuthal distributions are compared with theoretical predictions based on the random string approximation using different forms of the interatomic potential. ''Blocking'' in the transverse plane is also observed. In addition, from an analysis of the radial spreading of the distribution the effects of inelastic scattering in the transverse plane are clearly seen

  10. Accelerating action of stresses on crystallization kinetics in silicon ion-implanted layers during pulsed heating

    International Nuclear Information System (INIS)

    Aleksandrov, L.N.

    1985-01-01

    Numerical simulation of the effect of stressed in ion-implanted layers on kinetics of amorphous phase transformations is performed. The suggested model of accounting stresses including concentration ones is based on the locality of action of interstitial addition atoms and on general structural inhomogeneity of amorphous semiconductor leading to the formation of areas of the facilitated phase transition. Accounting of effect of energy variation of silicon atoms interaction on probability of displacement events and atoms building in lattice points or atomic bonds disintegration allows one to trace the accelerating action of introduced by ion implantation stresses on the kinetics of layer crystallization during pulsed heating

  11. Modelling, design and analysis of liquid crystal waveguides in preferentially etched silicon grooves

    International Nuclear Information System (INIS)

    Bellini, Bob; Beccherelli, Romeo

    2009-01-01

    This paper presents a fully consistent theoretical framework for liquid crystal (LC) channel waveguides that have been experimentally demonstrated in previous publications. We revise the optical design of the LC waveguides in silicon grooves and implement here a vectorial, fully consistent model of the LC waveguide electro-optical behaviour, based on the finite element method. The numerical investigation shows that LC waveguides demonstrate properties of propagation control and switching. They switch on and off with a low applied voltage. We discuss the major design parameters of the device and the effect of loss-inducing control electrodes.

  12. Manufacturing and characterization of bent silicon crystals for studies of coherent interactions with negatively charged particles beams

    Energy Technology Data Exchange (ETDEWEB)

    Germogli, G.; Mazzolari, A.; Bandiera, L.; Bagli, E.; Guidi, V.

    2015-07-15

    Efficient steering of GeV-energy negatively charged particle beams was demonstrated to be possible with a new generation of thin bent silicon crystals. Suitable crystals were produced at the Sensor Semiconductor Laboratory of Ferrara starting from Silicon On Insulator wafers, adopting proper revisitation of silicon micromachining techniques such as Low Pressure Chemical Vapor Deposition, photolithography and anisotropic chemical etching. Mechanical holders, which allow to properly bend the crystal and to reduce unwanted torsions, were employed. Crystallographic directions and crystal holder design were optimized in order to excite quasi-mosaic effect along (1 1 1) planes. Prior to exposing the crystal to particle beams, a full set of characterizations were performed. Infrared interferometry was used to measure crystal thickness with high accuracy. White-light interferometry was employed to characterize surface deformational state and its torsion. High-resolution X-rays diffraction was used to precisely measure crystal bending angle along the beam. Manufactured crystals were installed and tested at the MAMI MAinz MIcrotron to steer sub-GeV electrons, and at SLAC to deflect an electron beam in the 1 to 10 GeV energy range.

  13. One-way optical transmission in silicon photonic crystal heterojunction with circular and square scatterers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dan, E-mail: liudanhu725@126.com [School of Physics and Mechanical & Electrical Engineering, Hubei University of Education, Wuhan, 430205 (China); Hu, Sen [School of Physics and Mechanical & Electrical Engineering, Hubei University of Education, Wuhan, 430205 (China); Gao, Yihua [Wuhan National Laboratory for Optoelectronics (WNLO), School of Physics, Huazhong University of Science and Technology (HUST), Wuhan, 430074 (China)

    2017-07-12

    A 2D orthogonal square-lattice photonic crystal (PC) heterojunction consisting of circular and square air holes in silicon is presented. Band structures are calculated using the plane wave expansion method, and the transmission properties are investigated by the finite-different time-domain simulations. Thanks to the higher diffraction orders excited when the circular and square holes are interlaced along the interface, one-way transmission phenomena can exist within wide frequency regions. The higher order diffraction is further enhanced through two different interface optimization designs proposed by modifying the PC structure of the hetero-interface. An orthogonal PC heterojunction for wide-band and efficient one-way transmission is constructed, and the maximum transmissivity is up to 78%. - Highlights: • Photonic crystal heterojunction with circular and square scatterers is first studied. • One-way transmission efficiency is closely related to the hetero-interface. • Wide-band and efficient one-way transmission is realized.

  14. Enhanced photoresponsivity in graphene-silicon slow-light photonic crystal waveguides

    International Nuclear Information System (INIS)

    Zhou, Hao; Gu, Tingyi; McMillan, James F.; Yu, Mingbin; Lo, Guoqiang; Kwong, Dim-Lee; Feng, Guoying; Zhou, Shouhuan; Wong, Chee Wei

    2016-01-01

    We demonstrate the enhanced fast photoresponsivity in graphene hybrid structures by combining the ultrafast dynamics of graphene with improved light-matter interactions in slow-light photonic crystal waveguides. With a 200 μm interaction length, a 0.8 mA/W photoresponsivity is achieved in a graphene-silicon Schottky-like photodetector, with an operating bandwidth in excess of 5 GHz and wavelength range at least from 1480 nm to 1580 nm. Fourfold enhancement of the photocurrent is observed in the slow light region, compared to the wavelength far from the photonic crystal bandedge, for a chip-scale broadband fast photodetector.

  15. 10 Gb/s operation of photonic crystal silicon optical modulators.

    Science.gov (United States)

    Nguyen, Hong C; Sakai, Yuya; Shinkawa, Mizuki; Ishikura, Norihiro; Baba, Toshihiko

    2011-07-04

    We report the first experimental demonstration of 10 Gb/s modulation in a photonic crystal silicon optical modulator. The device consists of a 200 μm-long SiO2-clad photonic crystal waveguide, with an embedded p-n junction, incorporated into an asymmetric Mach-Zehnder interferometer. The device is integrated on a SOI chip and fabricated by CMOS-compatible processes. With the bias voltage set at 0 V, we measure a V(π)L pseudo-random bit sequence signal. An open eye pattern is observed at bitrates of 10 Gb/s and 2 Gb/s, with and without pre-emphasis of the drive signal, respectively.

  16. Combined effects of crucible geometry and Marangoni convection on silicon Czochralski crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, F. [Unit of Developpement of Silicon Technologie, Algiers (Algeria); Bouabdallah, A.; Zizi, M. [LTSE Laboratory, University of Science and Technology USTHB., Babezzouar, Algiers (Algeria); Hanchi, S. [UER Mecanique/ E.M.P/ B.P, El Bahri/Alger (Algeria); Alemany, A. [Laboratoire EPM, CNRS, Grenoble (France)

    2009-08-15

    In order to understand the influence of crucible geometry combined with natural convection and Marangoni convection on melt flow pattern, temperature and pressure fields in silicon Czochralski crystal growth process, a set of numerical simulations was conducted. We carry out calculation enable us to determine temperature, pressure and velocity fields in function of Grashof and Marangoni numbers. The essential results show that the hemispherical geometry of crucible seems to be adapted for the growth of a good quality crystal and the pressure field is strongly affected by natural and Marangoni convection and it is more sensitive than temperature. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Channeling, volume reflection, and volume capture study of electrons in a bent silicon crystal

    Directory of Open Access Journals (Sweden)

    T. N. Wistisen

    2016-07-01

    Full Text Available We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111 plane in a strongly bent quasimosaic silicon crystal. These phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5, and 14.0 GeV with a crystal with bending radius of 0.15 m, corresponding to curvatures of 0.053, 0.066, 0.099, 0.16, and 0.22 times the critical curvature, respectively. Based on the parameters of fitting functions we have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission, and the widths of the distribution of channeled particles parallel and orthogonal to the plane.

  18. Role of Laser Power, Wavelength, and Pulse Duration in Laser Assisted Tin-Induced Crystallization of Amorphous Silicon

    Directory of Open Access Journals (Sweden)

    V. B. Neimash

    2018-01-01

    Full Text Available This work describes tin-induced crystallization of amorphous silicon studied with Raman spectroscopy in thin-film structures Si-Sn-Si irradiated with pulsed laser light. We have found and analyzed dependencies of the nanocrystals’ size and concentration on the laser pulse intensity for 10 ns and 150 μm duration laser pulses at the wavelengths of 535 nm and 1070 nm. Efficient transformation of the amorphous silicon into a crystalline phase during the 10 ns time interval of the acting laser pulse in the 200 nm thickness films of the amorphous silicon was demonstrated. The results were analyzed theoretically by modeling the spatial and temporal distribution of temperature in the amorphous silicon sample within the laser spot location. Simulations confirmed importance of light absorption depth (irradiation wavelength in formation and evolution of the temperature profile that affects the crystallization processes in irradiated structures.

  19. Process design and simulation for optimizing the oxygen concentration in Czochralski-grown single-crystal silicon

    International Nuclear Information System (INIS)

    Jung, Y. J.; Kim, W. K.; Jung, J. H.

    2014-01-01

    The highest-concentration impurity in a single-crystal silicon ingot is oxygen, which infiltrates the ingot during growth stage. This oxygen adversely affects the wafer is quality. This study was aimed at finding an optimal design for the Czochralski (Cz) process to enable high-quality and low cost (by reducing power consumption) wafer production by controlling the oxygen concentration in the silicon ingots. In the Cz process, the characteristics of silicon ingots during crystallization are greatly influenced by the design and the configuration of the hot zone, and by crystallization rate. In order to identify process conditions for obtaining an optimal oxygen concentration of 11 - 13 ppma (required for industrial-grade ingots), designed two shield shapes for the hot zone. Furthermore, oxygen concentrations corresponding to these two shapes were compared by evaluating each shape at five different production speeds. In addition, simulations were performed to identify the optimal shield design for industrial applications.

  20. Process design and simulation for optimizing the oxygen concentration in Czochralski-grown single-crystal silicon

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Y. J.; Kim, W. K.; Jung, J. H. [Yeungnam University, Gyeongsan (Korea, Republic of)

    2014-08-15

    The highest-concentration impurity in a single-crystal silicon ingot is oxygen, which infiltrates the ingot during growth stage. This oxygen adversely affects the wafer is quality. This study was aimed at finding an optimal design for the Czochralski (Cz) process to enable high-quality and low cost (by reducing power consumption) wafer production by controlling the oxygen concentration in the silicon ingots. In the Cz process, the characteristics of silicon ingots during crystallization are greatly influenced by the design and the configuration of the hot zone, and by crystallization rate. In order to identify process conditions for obtaining an optimal oxygen concentration of 11 - 13 ppma (required for industrial-grade ingots), designed two shield shapes for the hot zone. Furthermore, oxygen concentrations corresponding to these two shapes were compared by evaluating each shape at five different production speeds. In addition, simulations were performed to identify the optimal shield design for industrial applications.

  1. Large-scale membrane transfer process: its application to single-crystal-silicon continuous membrane deformable mirror

    International Nuclear Information System (INIS)

    Wu, Tong; Sasaki, Takashi; Hane, Kazuhiro; Akiyama, Masayuki

    2013-01-01

    This paper describes a large-scale membrane transfer process developed for the construction of large-scale membrane devices via the transfer of continuous single-crystal-silicon membranes from one substrate to another. This technique is applied for fabricating a large stroke deformable mirror. A bimorph spring array is used to generate a large air gap between the mirror membrane and the electrode. A 1.9 mm × 1.9 mm × 2 µm single-crystal-silicon membrane is successfully transferred to the electrode substrate by Au–Si eutectic bonding and the subsequent all-dry release process. This process provides an effective approach for transferring a free-standing large continuous single-crystal-silicon to a flexible suspension spring array with a large air gap. (paper)

  2. Correlation of the crystal orientation and electrical properties of silicon thin films on glass crystallized by line focus diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J., E-mail: j.yun@unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Huang, J.; Teal, A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Kim, K. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Suntech R& D Australia, Botany, NSW 2019 (Australia); Varlamov, S.; Green, M.A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2016-06-30

    In this work, crystallographic orientation of polycrystalline silicon films on glass formed by continuous wave diode laser crystallization was studied. Most of the grain boundaries were coincidence lattice Σ3 twin boundaries and other types of boundaries such as, Σ6, Σ9, and Σ21 were also frequently observed. The highest photoluminescence signal and mobility were observed for a grain with (100) orientation in the normal direction. X-ray diffraction results showed the highest occupancies between 41 and 70% along the (110) orientation. However, the highest occupancies changed to (100) orientation when a 100 nm thick SiO{sub x} capping layer was applied. Suns-Voc measurement and photoluminescence showed that higher solar cell performance is obtained from the cell crystallized with the capping layer, which is suspected from increased occupancies of (100) orientation. - Highlights: • Linear grains parallel to the scan direction formed with high density. • Σ3 coincidence lattice (CSL) boundaries found inside a grain • Grain boundaries exhibit various CSL boundaries such as Σ9, Σ18, and Σ27. • Grain with < 100 > orientation in normal direction showed highest electrical properties. • Improved voltage observed when percentage of < 100 > normal orientation is increased.

  3. Liquid gallium cooling of silicon crystals in high intensity photon beam

    International Nuclear Information System (INIS)

    Smither, R.K.; Forster, G.A.; Bilderback, D.H.

    1988-11-01

    The high-brilliance, insertion-device-based, photon beams of the next generation of synchrotron sources will deliver large thermal loads (1 kW to 10 kW) to the first optical elements. Considering the problems that present synchrotron users are experiencing with beams from recently installed insertion devices, new and improved methods of cooling these first optical elements, particularly when they are diffraction crystals, are clearly needed. A series of finite element calculations were performed to test the efficiency of new cooling geometries and new cooling fluids. The best results were obtained with liquid Ga metal flowing in channels just below the surface of the crystal. Ga was selected because of its good thermal conductivity and thermal capacity, low melting point, high boiling point, low kinetic viscosity, and very low vapor pressure. Its very low vapor pressure, even at elevated temperatures, makes it especially attractive in uhv conditions. A series of experiments were conducted at CHESS in February of 1988 that compared liquid gallium cooled silicon diffraction crystals with water cooled crystals. 2 refs., 16 figs., 1 tab

  4. Microstrip silicon detectors in a bent crystal based collimation system: The UA9 experiment

    International Nuclear Information System (INIS)

    Bolognini, D.

    2010-01-01

    In a hadron accelerator like Lhc, a collimation system needs to be developed to protect the accelerator itself from the beam loss damage, increasing the beam luminosity. At present, a classical robust multi-stage collimation system (based on amorphous jaws) allows to protect Lhc, but limits the luminosity to the 40% of the nominal value. In order to solve this problem, a series of low-impedance collimation systems is being developed for the second Lhc collimation phase: among these, a key role could be played by bent crystals. In a bent crystal, in fact, charged particles can be deviated in a given direction with a high efficiency, reducing the impedance and increasing the luminosity. After the satisfactory results on extracted beams, it was decided to test bent crystals on a circular accelerator (the Super Proton Synchrotron Sps at CERN): the UA9 experiment was born. In order to qualify the crystal behavior, a tracking system has been developed: the system is based on microstrip silicon detectors readout by self-triggering ASICs with a spatial resolution of the order of 5 μm; the system, completely remotely controlled and based on the optical fiber transmission, would be able to measure the beam halo phase space x - x 1 . This paper, after a brief introduction of the UA9 experiment, will describe the tracking system and the first results obtained in the commissioning phase and data takings with a detector prototype.

  5. Forced and thermocapillary convection in silicon Czochralski crystal growth in semispherical crucible

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, F [Physics Department, Faculty of Science, University of Mouloud Mammeri, Tizi Ouzou (Algeria); Bouabdallah, A; Zizi, M [LTSE Laboratory, University of Science and Technology USTHB. BP 32 Elalia, Babezzouar, Algiers (Algeria); Hanchi, S [UER Mecanique/ E.M.P B.P 17, Bordj El Bahri, Algiers (Algeria); Alemany, A, E-mail: abouab2002@yahoo.f [Laboratoire EPM, CNRS, Grenoble (France)

    2010-03-01

    In order to understand the influence of a semispherical crucible geometry combined with different convection modes as a thermocapillary convection, natural convection and forced convection, induced by crystal rotation, on melt flow pattern in silicon Czochralski crystal growth process, a set of numerical simulations are conducted using Fluent Software. We solve the system of equations of heat and momentum transfer in classical geometry as cylindrical and modified crystal growth process geometry as cylindro-spherical. In addition, we adopt hypothesis adapted to boundary conditions near the interface and calculations are executed to determine temperature, pressure and velocity fields versus Grashof and Reynolds numbers. The analysis of the obtained results led to conclude that there is advantage to modify geometry in comparison with the traditional one. The absence of the stagnation regions of fluid in the hemispherical crucible corner and the possibility to control the melt flow using the crystal rotation enhances the quality of the process comparatively to the cylindrical one. The pressure field is strongly related to the swirl velocity.

  6. Forced and thermocapillary convection in silicon Czochralski crystal growth in semispherical crucible

    International Nuclear Information System (INIS)

    Mokhtari, F; Bouabdallah, A; Zizi, M; Hanchi, S; Alemany, A

    2010-01-01

    In order to understand the influence of a semispherical crucible geometry combined with different convection modes as a thermocapillary convection, natural convection and forced convection, induced by crystal rotation, on melt flow pattern in silicon Czochralski crystal growth process, a set of numerical simulations are conducted using Fluent Software. We solve the system of equations of heat and momentum transfer in classical geometry as cylindrical and modified crystal growth process geometry as cylindro-spherical. In addition, we adopt hypothesis adapted to boundary conditions near the interface and calculations are executed to determine temperature, pressure and velocity fields versus Grashof and Reynolds numbers. The analysis of the obtained results led to conclude that there is advantage to modify geometry in comparison with the traditional one. The absence of the stagnation regions of fluid in the hemispherical crucible corner and the possibility to control the melt flow using the crystal rotation enhances the quality of the process comparatively to the cylindrical one. The pressure field is strongly related to the swirl velocity.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  8. In situ observation of shear-driven amorphization in silicon crystals

    Energy Technology Data Exchange (ETDEWEB)

    He, Yang; Zhong, Li; Fan, Feifei; Wang, Chongmin; Zhu, Ting; Mao, Scott X.

    2016-09-19

    Amorphous materials have attracted great interest in the scientific and technological fields. An amorphous solid usually forms under the externally driven conditions of melt-quenching, irradiation and severe mechanical deformation. However, its dynamic formation process remains elusive. Here we report the in situ atomic-scale observation of dynamic amorphization processes during mechanical straining of nanoscale silicon crystals by high resolution transmission electron microscopy (HRTEM). We observe the shear-driven amorphization (SDA) occurring in a dominant shear band. The SDA involves a sequence of processes starting with the shear-induced diamond-cubic to diamond-hexagonal phase transition that is followed by dislocation nucleation and accumulation in the newly formed phase, leading to the formation of amorphous silicon. The SDA formation through diamond-hexagonal phase is rationalized by its structural conformity with the order in the paracrystalline amorphous silicon, which maybe widely applied to diamond-cubic materials. Besides, the activation of SDA is orientation-dependent through the competition between full dislocation nucleation and partial gliding.

  9. Optimization of plasma parameters for the production of silicon nano-crystals

    CERN Document Server

    Chaabane, N; Vach, H; Cabarrocas, P R I

    2003-01-01

    We use silane-hydrogen plasmas to synthesize silicon nano-crystals in the gas phase and thermophoresis to collect them onto a cooled substrate. To distinguish between nano-crystals formed in the plasma and those grown on the substrate, as a result of surface and subsurface reactions, we have simultaneously deposited films on a conventional substrate heated at 250 deg. C and on a second substrate cooled down to 90 deg. C. A series of samples deposited at various discharge pressures, in the range of 400 mTorr to 1.2 Torr, have been characterized by Raman spectroscopy and ellipsometry. At low pressure (400-500 mTorr), the films are amorphous on the cold substrate and micro-crystalline on the hot one. As pressure increases, gas phase reactions lead to the formation of nano-crystalline particles which are attracted by the cold substrate due to thermophoresis. Consequently, we obtain nano-crystalline silicon thin films on the cold substrate and amorphous thin films on the heated one in the pressure range of 600-900...

  10. EBSD analysis of polysilicon films formed by aluminium induced crystallization of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Tuezuen, O. [InESS, UMR 7163 CNRS-ULP, 23 rue du Loess, F-67037 Strasbourg Cedex 2 (France)], E-mail: Ozge.Tuzun@iness.c-strasbourg.fr; Auger, J.M. [InESS, UMR 7163 CNRS-ULP, 23 rue du Loess, F-67037 Strasbourg Cedex 2 (France); SMS Centre, UMR CNRS 5146, Ecole des Mines de Saint Etienne, 158 Cours Fauriel, 42023 Saint Etienne Cedex 2 (France); Gordon, I. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Focsa, A.; Montgomery, P.C. [InESS, UMR 7163 CNRS-ULP, 23 rue du Loess, F-67037 Strasbourg Cedex 2 (France); Maurice, C. [SMS Centre, UMR CNRS 5146, Ecole des Mines de Saint Etienne, 158 Cours Fauriel, 42023 Saint Etienne Cedex 2 (France); Slaoui, A. [InESS, UMR 7163 CNRS-ULP, 23 rue du Loess, F-67037 Strasbourg Cedex 2 (France); Beaucarne, G.; Poortmans, J. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium)

    2008-08-30

    Among the methods for enlarging the grain size of polycrystalline silicon (poly-Si) thin films, aluminium induced crystallization (AIC) of amorphous silicon is considered to be a very promising approach. In the AIC process, a thin a-Si layer on top of an aluminium layer crystallizes at temperatures well below the eutectic temperature of the Al/Si system (T{sub eu} = 577 deg. C). By means of electron backscattering diffraction (EBSD), we have mainly studied the effect of the aluminium layer quality varying the deposition system on the grain size, the defects and the preferential crystallographic orientation. We have found a strong correlation between the mean grain size and the size distribution with the Al deposition system and the surface quality. Furthermore, we show for the first time that more than 50% of the surface of the AIC films grown on alumina substrates are (103) preferentially oriented, instead of the commonly observed (100) preferential orientation. This may have important consequences for epitaxial thickening of the AIC layer into polysilicon absorber layers for solar cells.

  11. Study on control of defect mode in hybrid mirror chirped porous silicon photonic crystal

    Science.gov (United States)

    Chen, Ying; Luo, Pei; Han, Yangyang; Cui, Xingning; He, Lei

    2018-03-01

    Based on the optical resonance principle and the tight-binding theory, a hybrid mirror chirped porous silicon photonic crystal is proposed. The control of the defect mode in hybrid mirror chirped porous silicon photonic crystal is studied. Through the numerical simulation, the control regulations of the defect modes resulted by the number of the periodical layers for the fundamental unit and the cascading number of the chirped structures are analyzed, and the split and the degeneration of the defect modes resulted by the change of the relative location between the mirror structures and the quasi-mirror structures are discussed. The simulation results show that the band gap would be broadened with the increase of the chirp quantity and the layer number of unilateral chirp. Adjusting the structural parameters of the hybrid mirror structure, the multimode characteristics will occur in the band gap. The more the cascading number of the chirped units, the more the number of the filtering channels will be. In addition, with the increase of the relative location between the mirror structures and the quasi-mirror structures, the degeneration of the defect modes will occur and can obtain high Q value. The structure can provide effective theoretical references for the design the multi-channel filters and high Q value sensors.

  12. Temperature dependent evolution of wrinkled single-crystal silicon ribbons on shape memory polymers.

    Science.gov (United States)

    Wang, Yu; Yu, Kai; Qi, H Jerry; Xiao, Jianliang

    2017-10-25

    Shape memory polymers (SMPs) can remember two or more distinct shapes, and thus can have a lot of potential applications. This paper presents combined experimental and theoretical studies on the wrinkling of single-crystal Si ribbons on SMPs and the temperature dependent evolution. Using the shape memory effect of heat responsive SMPs, this study provides a method to build wavy forms of single-crystal silicon thin films on top of SMP substrates. Silicon ribbons obtained from a Si-on-insulator (SOI) wafer are released and transferred onto the surface of programmed SMPs. Then such bilayer systems are recovered at different temperatures, yielding well-defined, wavy profiles of Si ribbons. The wavy profiles are shown to evolve with time, and the evolution behavior strongly depends on the recovery temperature. At relatively low recovery temperatures, both wrinkle wavelength and amplitude increase with time as evolution progresses. Finite element analysis (FEA) accounting for the thermomechanical behavior of SMPs is conducted to study the wrinkling of Si ribbons on SMPs, which shows good agreement with experiment. Merging of wrinkles is observed in FEA, which could explain the increase of wrinkle wavelength observed in the experiment. This study can have important implications for smart stretchable electronics, wrinkling mechanics, stimuli-responsive surface engineering, and advanced manufacturing.

  13. Solid phase crystallized polycrystalline thin-films on glass from evaporated silicon for photovoltaic applications

    International Nuclear Information System (INIS)

    Song Dengyuan; Inns, Daniel; Straub, Axel; Terry, Mason L.; Campbell, Patrick; Aberle, Armin G.

    2006-01-01

    Polycrystalline silicon (poly-Si) thin-films are made on planar and textured glass substrates by solid phase crystallization (SPC) of in situ doped amorphous silicon (a-Si) deposited by electron-beam evaporation. These materials are referred to by us as EVA materials (SPC of evaporated a-Si). The properties of EVA poly-Si films are characterised by Raman microscopy, transmission electron microscopy, and X-ray diffraction. A narrow and symmetrical Raman peak at a wave number of about 520 cm -1 is observed for all samples, showing that the films are fully crystallized. X-ray diffraction (XRD) reveals that the films are preferentially (111)-oriented. Furthermore, the full width at half maximum of the dominant (111) XRD peaks indicates that the structural quality of the films is affected by the a-Si deposition temperature and the surface morphology of the glass substrates. A-Si deposition at 200 instead of 400 deg. C leads to an enhanced poly-Si grain size. On textured glass, the addition of a SiN barrier layer between the glass and the Si improves the poly-Si material quality. No such effect occurs on planar glass. Mesa-type solar cells are made from these EVA films on planar and textured glass. A strong correlation between the cells' current-voltage characteristics and their crystalline material quality is observed

  14. Influence of Crucible Thermal Conductivity on Crystal Growth in an Industrial Directional Solidification Process for Silicon Ingots

    Directory of Open Access Journals (Sweden)

    Zaoyang Li

    2016-01-01

    Full Text Available We carried out transient global simulations of heating, melting, growing, annealing, and cooling stages for an industrial directional solidification (DS process for silicon ingots. The crucible thermal conductivity is varied in a reasonable range to investigate its influence on the global heat transfer and silicon crystal growth. It is found that the crucible plays an important role in heat transfer, and therefore its thermal conductivity can influence the crystal growth significantly in the entire DS process. Increasing the crucible thermal conductivity can shorten the time for melting of silicon feedstock and growing of silicon crystal significantly, and therefore large thermal conductivity is helpful in saving both production time and power energy. However, the high temperature gradient in the silicon ingots and the locally concave melt-crystal interface shape for large crucible thermal conductivity indicate that high thermal stress and dislocation propagation are likely to occur during both growing and annealing stages. Based on the numerical simulations, some discussions on designing and choosing the crucible thermal conductivity are presented.

  15. Friction and metal transfer for single-crystal silicon carbide in contact with various metals in vacuum

    International Nuclear Information System (INIS)

    Miyoshi, K.; Buckley, D.H.

    1978-04-01

    Sliding friction experiments were conducted with single-crystal silicon carbide in contact with transition metals (tungsten, iron, rhodium, nickel, titanium, and cobalt), copper, and aluminum. Results indicate the coefficient of friction for a silicon carbide-metal system is related to the d bond character and relative chemical activity of the metal. The more active the metal, the higher the coefficient of friction. All the metals examined transferred to the surface of silicon carbide in sliding. The chemical activity of metal to silicon and carbon and shear modulus of the metal may play important roles in metal transfer and the form of the wear debris. The less active metal is, and the greater resistance to shear it has, with the exception of rhodium and tungsten, the less transfer to silicon carbide

  16. Formation and growth of crystal defects in directionally solidified multicrystalline silicon for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ryningen, Birgit

    2008-07-01

    Included in this thesis are five publications and one report. The common theme is characterisation of directionally solidified multicrystalline silicon for solar cells. Material characterisation of solar cell silicon is naturally closely linked to both the casting process and to the solar cell processing: Many of the material properties are determined by the casting process, and the solar cell processing will to some extend determine which properties will influence the solar cell performance. Solar grade silicon (SoG-Si) made by metallurgical refining route and supplied by Elkem Solar was directionally solidified and subsequently characterised, and a simple solar cell process was applied. Except from some metallic co-precipitates in the top of the ingot, no abnormalities were found, and it is suggested that within the limits of the tests performed in this thesis, the casting and the solar cell processing, rather than the assumed higher impurity content, was the limiting factor. It is suggested in this thesis that the main quality problem in multicrystalline silicon wafers is the existence of dislocation clusters covering large wafer areas. The clusters will reduce the effect of gettering and even if gettering could be performed successfully, the clusters will still reduce the minority carrier mobility and hence the solar cell performance. It has further been pointed out that ingots solidified under seemingly equal conditions might have a pronounced difference in minority carrier lifetime. Ingots with low minority carrier lifetime have high dislocation densities. The ingots with the substantially higher lifetime seem all to be dominated by twins. It is also found a link between a higher undercooling and the ingots dominated by twins. It is suggested that the two types of ingots are subject to different nucleation and crystal growth mechanisms: For the ingots dominated by dislocations, which are over represented, the crystal growth is randomly nucleated at the

  17. Control of heat transfer in continuous-feeding Czochralski-silicon crystal growth with a water-cooled jacket

    Science.gov (United States)

    Zhao, Wenhan; Liu, Lijun

    2017-01-01

    The continuous-feeding Czochralski method is an effective method to reduce the cost of single crystal silicon. By promoting the crystal growth rate, the cost can be reduced further. However, more latent heat will be released at the melt-crystal interface under a high crystal growth rate. In this study, a water-cooled jacket was applied to enhance the heat transfer at the melt-crystal interface. Quasi-steady-state numerical calculation was employed to investigate the impact of the water-cooled jacket on the heat transfer at the melt-crystal interface. Latent heat released during the crystal growth process at the melt-crystal interface and absorbed during feedstock melting at the feeding zone was modeled in the simulations. The results show that, by using the water-cooled jacket, heat transfer in the growing crystal is enhanced significantly. Melt-crystal interface deflection and thermal stress increase simultaneously due to the increase of radial temperature at the melt-crystal interface. With a modified heat shield design, heat transfer at the melt-crystal interface is well controlled. The crystal growth rate can be increased by 20%.

  18. Performance study of Philips digital silicon photomultiplier coupled to scintillating crystals

    International Nuclear Information System (INIS)

    Liu, Z.; Pizzichemi, M.; Paganoni, M.; Auffray, E.; Lecoq, P.

    2016-01-01

    Silicon photomultipliers (SiPMs) and scintillators are often arranged in the shape of arrays in Positron Emission Tomography (PET) systems. Digital SiPMs provide signal readout in single photon avalanche diode (SPAD) level. From the photon count rate measurement of each SPAD cell of digital SiPM, we found that the output scintillating photons distribute in an area larger than the scintillator physical coupling area. Taking advantage of the possibility to enable/disable individual cells of the digital SiPM, a group of Lutetium-yttrium oxyorthosilicate (LYSO) crystals with different dimensions coupled to a digital SiPM was used to study the influence of using different SiPM active area on the number of photons detected, energy resolution and coincidence time resolution (CTR). For the same crystal coupled to the digital SiPM, the larger the active area of digital SiPM, the higher the number of photons detected. The larger active area of the digital SiPM also results in a better energy resolution after saturation correction. The best energy resolution full width half maximum (FWHM) obtained for the 2×2×5mm 3 , 2×2×10 mm 3 , 2×2×15mm 3 , 2×2×20mm 3 LYSO crystals was 10.7%, 11.6%, 12.1%, 12.5%, respectively. For crystals with different cross sections coupled to the digital SiPM, we found that the larger the cross section of coupling area, the more photons were detected and thus a better energy resolution was obtained. The CTR of crystals fully wrapped with Teflon or without wrapping was measured by positioning two identical crystals facing each other. A larger area of digital SiPM improves the CTR and the CTR reaches the plateau when the active area is larger than 2.2×2.2mm 2 with both two configurations of wrapping. The best CTR value for the 2×2×5mm 3 , 2×2×10mm 3 , 2×2×15mm 3 , 2×2×20mm 3 LYSO crystals was 128.9 ps, 148.4 ps, 171.6 ps, 177.9 ps, respectively. The measurements performed lead us to conclude that optimising the coupling between crystal

  19. Microcrystalline silicon growth by low laser energy crystallization on a plastic substrate

    International Nuclear Information System (INIS)

    Kim, D. Y.; Seo, C. K.; Shim, M. S.; Kim, C. H.; Yi, J.

    2004-01-01

    We are reporting the crystallization of amorphous silicon (a-Si) using a XeCl excimer laser treatment. Although polycarbonate (PC) plastic substrates are very weak at high temperatures of more than 150 .deg. C, they are very useful for applications to microelectronics because of light weight, high transmittance, and flexibility. In order to crystallize a-Si films on plastic substrates, we suggest that a CeO 2 seed layer will be very helpful at a low laser energy density. The seed layer is deposited at room temperature by rf using magnetron sputtering. A seed layer deposition method will be also presented in detail in this article. We compare a-Si crytallization without a seed layer with one with a seed layer deposited between the a-Si and the plastic substrate. The a-Si was deposited on the plastic substrate by using inductively coupled plasma Chemical-Vapor Deposition (ICPCVD) at the room temperature. In this paper, we will present the crystallization properties of a-Si with and without a CeO 2 seed layer on the plastic substrate.

  20. Channeling experiments at planar diamond and silicon single crystals with electrons from the Mainz Microtron MAMI

    Science.gov (United States)

    Backe, H.; Lauth, W.; Tran Thi, T. N.

    2018-04-01

    Line structures were observed for (110) planar channeling of electrons in a diamond single crystal even at a beam energy of 180 MeV . This observation motivated us to initiate dechanneling length measurements as function of the beam energy since the occupation of quantum states in the channeling potential is expected to enhance the dechanneling length. High energy loss signals, generated as a result of emission of a bremsstrahlung photon with about half the beam energy at channeling of 450 and 855 MeV electrons, were measured as function of the crystal thickness. The analysis required additional assumptions which were extracted from the numerical solution of the Fokker-Planck equation. Preliminary results for diamond are presented. In addition, we reanalyzed dechanneling length measurements at silicon single crystals performed previously at the Mainz Microtron MAMI at beam energies between 195 and 855 MeV from which we conclude that the quality of our experimental data set is not sufficient to derive definite conclusions on the dechanneling length. Our experimental results are below the predictions of the Fokker-Planck equation and somewhat above the results of simulation calculations of A. V. Korol and A. V. Solov'yov et al. on the basis of the MBN Explorer simulation package. We somehow conservatively conclude that the prediction of the asymptotic dechanneling length on the basis of the Fokker-Planck equation represents an upper limit.

  1. Gamma-stimulated modification of structure and mechanical properties of silicon crystals

    International Nuclear Information System (INIS)

    Khaydarov, T.K.; Khamraeva, R.N.; Rustamova, V.M.; Ibragimova, E.M.; Kalanov, M.U.; Abdurakhimov, A.A.; Abdurakhmanov, A.A.

    2004-01-01

    Full text: The paper presents the results of gamma-irradiation effect on the fine structure and mechanical properties of silicon crystals. The objects of researches were p-Si single crystals with the following characteristics: ρ ≅ 10Ω · cm; N D ≅ 10 2 cm -2 ; N O ≅ 10 17 cm -3 ; N B ≅ 6· 10 15 cm -3 . The plate size were 20.8·4.1· 1.2 mm 3 with the surface oriented along {111}. The structure was studied at the diffractometer DRON-UM1 with CuK α - radiation ( λ = 0.1542 nm). The intrinsic friction (Q -1 ) of the samples was measured with the ultra-sonic resonance technique at the frequency of 148 kHz of the plate bending oscillations. The samples were irradiated at the INP AS RUz 60 Co gamma-facility (E γ ≅ 1.2 MeV) in the dose range of 10 1 † 10 7 Gy at 320 K. The dose dependence of Q -1 had a non-monotonous character. The irradiation to the dose of 5·10 3 Gy resulted in increasing the initial value of Q -1 due to irradiation induced growth of the point defect concentration and accumulating of the elastic lattice strains. It is also evidenced by the symmetric broadening of the structure reflection (111). At the dose of 5 ·10 3 Gy the strain value seems to gain the upper fluidity limit of (6 †15) ·10 -8 N/m 2 , after which a weak splitting of the (111) reflection appears, meaning the beginning of twin formation in the form of insertion stock defects with partial dislocations. At dose increasing to 10 4 Gy the twins cause the sharp drop of Q -1 , related with decreasing of the elastic strains, which stops at the dose of 5·10 4 Gy probably due to reaching the lower limit of fluidity for silicon ((1† 4) · 10 -8 N/m 2 ), when the process of the twin defect formation completes. This mechanism is confirmed by the total splitting of the structure peak (111) and practical independence of Q -1 on dose till 10 7 Gy. Thus, gamma-irradiation in the studied dose range modifies the existing lattice imperfectness, that influences upon both mechanical

  2. Silicone stent placement for primary tracheal amyloidosis accompanied by cartilage destruction.

    Science.gov (United States)

    Ryu, Duck Hyun; Eom, Jung Seop; Jeong, Ho Jung; Kim, Jung Hoon; Lee, Ji Eun; Jun, Ji Eun; Song, Dae Hyun; Han, Joungho; Kim, Hojoong

    2014-06-01

    Primary tracheal amyloidosis (PTA) can lead to airway obstructions, and patients with severe PTA should undergo bronchoscopic interventions in order to maintain airway patency. Focal airway involvements with amyloidosis can only be treated with mechanical dilatation. However, the PTA with diffused airway involvements and concomitant cartilage destructions requires stent placement. Limited information regarding the usefulness of silicone stents in patients with PTA has been released. Therefore, we report a case of diffused PTA with tracheomalacia causing severe cartilage destruction, which is being successfully managed with bronchoscopic interventions and silicone stent placements.

  3. Light-trapping optimization in wet-etched silicon photonic crystal solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Eyderman, Sergey, E-mail: sergey.eyderman@utoronto.ca [Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7 (Canada); John, Sajeev [Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7 (Canada); Department of Physics, King Abdul-Aziz University, Jeddah (Saudi Arabia); Hafez, M.; Al-Ameer, S. S.; Al-Harby, T. S.; Al-Hadeethi, Y. [Department of Physics, King Abdul-Aziz University, Jeddah (Saudi Arabia); Bouwes, D. M. [iX-factory GmbH, Konrad Adenauer–Allee 11, 44263 Dortmund (Germany)

    2015-07-14

    We demonstrate, by numerical solution of Maxwell's equations, near-perfect solar light-trapping and absorption over the 300–1100 nm wavelength band in silicon photonic crystal (PhC) architectures, amenable to fabrication by wet-etching and requiring less than 10 μm (equivalent bulk thickness) of crystalline silicon. These PhC's consist of square lattices of inverted pyramids with sides comprised of various (111) silicon facets and pyramid center-to-center spacing in the range of 1.3–2.5 μm. For a wet-etched slab with overall height H = 10 μm and lattice constant a = 2.5 μm, we find a maximum achievable photo-current density (MAPD) of 42.5 mA/cm{sup 2}, falling not far from 43.5 mA/cm{sup 2}, corresponding to 100% solar absorption in the range of 300–1100 nm. We also demonstrate a MAPD of 37.8 mA/cm{sup 2} for a thinner silicon PhC slab of overall height H = 5 μm and lattice constant a = 1.9 μm. When H is further reduced to 3 μm, the optimal lattice constant for inverted pyramids reduces to a = 1.3 μm and provides the MAPD of 35.5 mA/cm{sup 2}. These wet-etched structures require more than double the volume of silicon, in comparison to the overall mathematically optimum PhC structure (consisting of slanted conical pores), to achieve the same degree of solar absorption. It is suggested these 3–10 μm thick structures are valuable alternatives to currently utilized 300 μm-thick textured solar cells and are suitable for large-scale fabrication by wet-etching.

  4. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    International Nuclear Information System (INIS)

    Yan, Hai; Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-01-01

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed

  5. 14 MeV neutron activation analysis for oxygen determination in silicon single-crystals

    International Nuclear Information System (INIS)

    Timus, D.M.; Galatanu, V.; Catana, D.

    1985-01-01

    The nondestructive fast neutron activation method has been applied for the total oxygen content determination with regards to the correlation of this content with the material properties of the silicon. The nuclear reaction used is: 16 O (n,p) 16 N, (Tsub(1/2)=7,4 s). The equipment and experimental set-up of the analytical system contained fast neutron generator GENEDAC, gamma scintillation detector (NaI crystal), a photomultiplier, a preamplifier, a linear amplifier with variable energy discrimination thresholds and a pneumatic conveyor system. The method proposed is rapid (total analysis time is less than 60 s), specific (allows a good energetic discrimination in relation to other elements) and precise, being able to characterize nondestructively the whole volume of the analysed sample

  6. Interference effects in Bragg-case synchrotron section topography of elastically bent silicon implanted crystals

    International Nuclear Information System (INIS)

    Wierzchowski, W.; Wieteska, K.; Graeff, W.

    1997-01-01

    White-beam synchrotron section topography was applied to a silicon crystal implanted with 4.8 MeV α-particles elastically bent with the radius of curvature close to 100 m. A number of section patterns corresponding to different reflections was analysed. It was found that the section pattern in the bent sample was drastically different from those observed in a flat sample. The difference consists in the occurrence of the sets of additional interference fringes covering a long distance up to several millimetres behind the main diffraction maximum. It was possible to reproduce some characteristic features of the fringes both in the implanted and non-implanted region by numerical integration of the Takagi-Taupin equation

  7. Crystallization to polycrystalline silicon thin film and simultaneous inactivation of electrical defects by underwater laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Machida, Emi [Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192 (Japan); Research Fellowships of the Japan Society for the Promotion of Science, Japan Society for the Promotion of Science, 1-8 Chiyoda, Tokyo 102-8472 (Japan); Horita, Masahiro; Ishikawa, Yasuaki; Uraoka, Yukiharu [Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192 (Japan); Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ikenoue, Hiroshi [Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395 (Japan)

    2012-12-17

    We propose a low-temperature laser annealing method of a underwater laser annealing (WLA) for polycrystalline silicon (poly-Si) films. We performed crystallization to poly-Si films by laser irradiation in flowing deionized-water where KrF excimer laser was used for annealing. We demonstrated that the maximum value of maximum grain size of WLA samples was 1.5 {mu}m, and that of the average grain size was 2.8 times larger than that of conventional laser annealing in air (LA) samples. Moreover, WLA forms poly-Si films which show lower conductivity and larger carrier life time attributed to fewer electrical defects as compared to LA poly-Si films.

  8. Lightweight and High-Resolution Single Crystal Silicon Optics for X-ray Astronomy

    Science.gov (United States)

    Zhang, William W.; Biskach, Michael P.; Chan, Kai-Wing; Mazzarella, James R.; McClelland, Ryan S.; Riveros, Raul E.; Saha, Timo T.; Solly, Peter M.

    2016-01-01

    We describe an approach to building mirror assemblies for next generation X-ray telescopes. It incorporates knowledge and lessons learned from building existing telescopes, including Chandra, XMM-Newton, Suzaku, and NuSTAR, as well as from our direct experience of the last 15 years developing mirror technology for the Constellation-X and International X-ray Observatory mission concepts. This approach combines single crystal silicon and precision polishing, thus has the potential of achieving the highest possible angular resolution with the least possible mass. Moreover, it is simple, consisting of several technical elements that can be developed independently in parallel. Lastly, it is highly amenable to mass production, therefore enabling the making of telescopes of very large photon collecting areas.

  9. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Hai, E-mail: hai.yan@utexas.edu; Zou, Yi; Yang, Chun-Ju [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Chakravarty, Swapnajit, E-mail: swapnajit.chakravarty@omegaoptics.com [Omega Optics, Inc., 8500 Shoal Creek Blvd., Austin, Texas 78757 (United States); Wang, Zheng [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States); Tang, Naimei; Chen, Ray T., E-mail: raychen@uts.cc.utexas.edu [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Omega Optics, Inc., 8500 Shoal Creek Blvd., Austin, Texas 78757 (United States); Fan, Donglei [Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States); Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  10. Effect of irradiation temperature and initial crystal doping level on defect creation efficiency in silicon

    International Nuclear Information System (INIS)

    Korshunov, F.P.; Markevich, V.P.; Medvedeva, I.F.; Murin, L.I.

    1990-01-01

    The defect creation processes in n-type silicon irradiated by 60 Co gamma-rays or fast electrons (E = 4 MeV) have been investigated. Using electrical measurements the dependences of introduction efficiencies of the main radiation defects (A-, E-centres, carbon-related complexes) on the irradiation temperature (T irr = 77-470 K) and material doping level (N h = 2 x 10 12 - 2 x 10 15 cm -3 ) are obtained. It is shown that the efficiency of these defects formation is conditioned by the probability of the Frenkel pairs separation and depends strongly on the Fermi level position in crystals being irradiated. 9 refs.; 3 figs.; 1 tab

  11. Electronic properties of dislocations introduced mechanically at room temperature on a single crystal silicon surface

    International Nuclear Information System (INIS)

    Ogawa, Masatoshi; Kamiya, Shoji; Izumi, Hayato; Tokuda, Yutaka

    2012-01-01

    This paper focuses on the effects of temperature and environment on the electronic properties of dislocations in n-type single crystal silicon near the surface. Deep level transient spectroscopy (DLTS) analyses were carried out with Schottky electrodes and p + -n junctions. The trap level, originally found at E C -0.50 eV (as commonly reported), shifted to a shallower level at E C -0.23 eV after a heat treatment at 350 K in an inert environment. The same heat treatment in lab air, however, did not cause any shift. The trap level shifted by the heat treatment in an inert environment was found to revert back to the original level when the specimens were exposed to lab air again. Therefore, the intrinsic trap level is expected to occur at E C -0.23 eV and shift sensitively with gas adsorption in air.

  12. Polarization Beam Splitter Based on a Self-Collimation Michelson Interferometer in a Silicon Photonic Crystal

    International Nuclear Information System (INIS)

    Chen Xi-Yao; Lin Gui-Min; Li Jun-Jun; Xu Xiao-Fu; Jiang Jun-Zhen; Qiang Ze-Xuan; Qiu Yi-Shen; Li Hui

    2012-01-01

    A polarization beam splitter based on a self-collimation Michelson interferometer (SMI) in a hole-type silicon photonic crystal is proposed and numerically demonstrated. Utilizing the polarization dependence of the transmission spectra of the SMI and polarization peak matching method, the SMI can work as a polarization beam splitter (PBS) by selecting an appropriate path length difference in the structure. Based on its novel polarization beam splitting mechanics, the polarization extinction ratios (PERs) for TM and TE modes are as high as 18.4 dB and 24.3 dB, respectively. Since its dimensions are only several operating wavelengths, the PBS may have practical applications in photonic integrated circuits. (fundamental areas of phenomenology(including applications))

  13. Plasmonic enhancement of a silicon-vacancy center in a nanodiamond crystal

    Science.gov (United States)

    Meng, Xiang; Liu, Shang; Dadap, Jerry I.; Osgood, Richard M.

    2017-06-01

    This work reports a rigorous and comprehensive three-dimensional electromagnetic computation to investigate and design photoluminescence enhancement from a single silicon-vacancy center (SVC) in a nanodiamond crystal embedded in various metallic nanoantennae, each having a different geometry. The study demonstrates how each antenna design enhances the photoluminescence of SVCs in diamond. In particular, our report discusses how the 2D or 3D curvature of the nanoantenna and the control of the local environment of the SVC can lead to significant field enhancement of its optical field. Our calculated optimal photoluminescence for each design enhances the emission intensity by 15 -300 × that of a single SVC without antenna. The enhancement mechanisms are investigated using four representative structures that can be fabricated under feasible and realistic growth conditions, i.e., spherical-, nanorod-, nanodisk-dimer, and bow-tie nanoantennae. These results demonstrate a method for rationally designing arbitrary metallic nanoantenna/emitter assemblies to achieve optimal SVC photoluminescence.

  14. Beam tests of lead tungstate crystal matrices and a silicon strip preshower detector for the CMS electromagnetic calorimeter

    CERN Document Server

    Auffray, Etiennette; Barney, D; Bassompierre, Gabriel; Benhammou, Ya; Blick, A M; Bloch, P; Bonamy, P; Bourotte, J; Buiron, L; Cavallari, F; Chipaux, Rémi; Cockerill, D J A; Dafinei, I; Davies, G; Depasse, P; Deiters, K; Diemoz, M; Dobrzynski, Ludwik; Donskov, S V; Mamouni, H E; Ercoli, C; Faure, J L; Felcini, Marta; Gautheron, F; Géléoc, M; Givernaud, Alain; Gninenko, S N; Godinovic, N; Graham, D J; Guillaud, J P; Guschin, E; Haguenauer, Maurice; Hillemanns, H; Hofer, H; Ille, B; Inyakin, A V; Jääskeläinen, S; Katchanov, V A; Kirn, T; Kloukinas, Kostas C; Korzhik, M V; Lassila-Perini, K M; Lebrun, P; Lecoq, P; Lecoeur, Gérard; Lecomte, P; Leonardi, E; Locci, E; Loos, R; Longo, E; MacKay, C K; Martin, E; Mendiburu, J P; Musienko, Yu V; Nédélec, P; Nessi-Tedaldi, F; Organtini, G; Paoletti, S; Pansart, J P; Peigneux, J P; Puljak, I; Qian, S; Reid, E; Renker, D; Rosowsky, A; Rosso, E; Rusack, R W; Rykaczewski, H; Schneegans, M; Seez, Christopher J; Semeniouk, I N; Shagin, P M; Sillou, D; Singovsky, A V; Sougonyaev, V; Soric, I; Verrecchia, P; Vialle, J P; Virdee, Tejinder S; Zhu, R Y

    1998-01-01

    Tests of lead tungstate crystal matrices carried out in high-energy electron beams in 1996, using new crystals, new APDs and an improved test set-up, confirm that an energy resolution of better than 0 .6% at 100 GeV can be obtained when the longitudinal uniformity of the struck crystal is adequate. Light loss measurements under low dose irradiation are reported. It is shown that there is no loss of energy resolution after irradiation and that the calibration change due to light loss can be tracked with a precision monitoring system. Finally, successuful tests with a preshower device, equipped wi th silicon strip detector readout, are described.

  15. Subsurface damage mechanism of high speed grinding process in single crystal silicon revealed by atomistic simulations

    International Nuclear Information System (INIS)

    Li, Jia; Fang, Qihong; Zhang, Liangchi; Liu, Youwen

    2015-01-01

    Highlights: • Molecular dynamic model of nanoscale high speed grinding of silicon workpiece has been established. • The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation during high speed grinding process are thoroughly investigated. • Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle. • The hydrostatic stress and von Mises stress by the established analytical model are studied subsurface damage mechanism during nanoscale grinding. - Abstract: Three-dimensional molecular dynamics (MD) simulations are performed to investigate the nanoscale grinding process of single crystal silicon using diamond tool. The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation are studied. We also establish an analytical model to calculate several important stress fields including hydrostatic stress and von Mises stress for studying subsurface damage mechanism, and obtain the dislocation density on the grinding subsurface. The results show that a higher grinding velocity in machining brittle material silicon causes a larger chip and a higher temperature, and reduces subsurface damage. However, when grinding velocity is above 180 m s −1 , subsurface damage thickness slightly increases because a higher grinding speed leads to the increase in grinding force and temperature, which accelerate dislocation nucleation and motion. Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle, that provides valuable reference for machining nanometer devices. The von Mises stress and the hydrostatic stress play an important role in the grinding process, and explain the subsurface damage though dislocation mechanism under high

  16. Designing High-Efficiency Thin Silicon Solar Cells Using Parabolic-Pore Photonic Crystals

    Science.gov (United States)

    Bhattacharya, Sayak; John, Sajeev

    2018-04-01

    We demonstrate the efficacy of wave-interference-based light trapping and carrier transport in parabolic-pore photonic-crystal, thin-crystalline silicon (c -Si) solar cells to achieve above 29% power conversion efficiencies. Using a rigorous solution of Maxwell's equations through a standard finite-difference time domain scheme, we optimize the design of the vertical-parabolic-pore photonic crystal (PhC) on a 10 -μ m -thick c -Si solar cell to obtain a maximum achievable photocurrent density (MAPD) of 40.6 mA /cm2 beyond the ray-optical, Lambertian light-trapping limit. For a slanted-parabolic-pore PhC that breaks x -y symmetry, improved light trapping occurs due to better coupling into parallel-to-interface refraction modes. We achieve the optimum MAPD of 41.6 mA /cm2 for a tilt angle of 10° with respect to the vertical axis of the pores. This MAPD is further improved to 41.72 mA /cm2 by introducing a 75-nm SiO2 antireflective coating on top of the solar cell. We use this MAPD and the associated charge-carrier generation profile as input for a numerical solution of Poisson's equation coupled with semiconductor drift-diffusion equations using a Shockley-Read-Hall and Auger recombination model. Using experimentally achieved surface recombination velocities of 10 cm /s , we identify semiconductor doping profiles that yield power conversion efficiencies over 29%. Practical considerations of additional upper-contact losses suggest efficiencies close to 28%. This improvement beyond the current world record is largely due to an open-circuit voltage approaching 0.8 V enabled by reduced bulk recombination in our thin silicon architecture while maintaining a high short-circuit current through wave-interference-based light trapping.

  17. Deep and tapered silicon photonic crystals for achieving anti-reflection and enhanced absorption.

    Science.gov (United States)

    Hung, Yung-Jr; Lee, San-Liang; Coldren, Larry A

    2010-03-29

    Tapered silicon photonic crystals (PhCs) with smooth sidewalls are realized using a novel single-step deep reactive ion etching. The PhCs can significantly reduce the surface reflection over the wavelength range between the ultra-violet and near-infrared regions. From the measurements using a spectrophotometer and an angle-variable spectroscopic ellipsometer, the sub-wavelength periodic structure can provide a broad and angular-independent antireflective window in the visible region for the TE-polarized light. The PhCs with tapered rods can further reduce the reflection due to a gradually changed effective index. On the other hand, strong optical resonances for TM-mode can be found in this structure, which is mainly due to the existence of full photonic bandgaps inside the material. Such resonance can enhance the optical absorption inside the silicon PhCs due to its increased optical paths. With the help of both antireflective and absorption-enhanced characteristics in this structure, the PhCs can be used for various applications.

  18. Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides

    Science.gov (United States)

    Yan, Siqi; Zhu, Xiaolong; Frandsen, Lars Hagedorn; Xiao, Sanshui; Mortensen, N. Asger; Dong, Jianji; Ding, Yunhong

    2017-01-01

    Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light–matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally demonstrate an energy-efficient graphene microheater with a tuning efficiency of 1.07 nmmW−1 and power consumption per free spectral range of 3.99 mW. The rise and decay times (10–90%) are only 750 and 525 ns, which, to the best of our knowledge, are the fastest reported response times for microheaters in silicon photonics. The corresponding figure of merit of the device is 2.543 nW s, one order of magnitude better than results reported in previous studies. The influence of the length and shape of the graphene heater to the tuning efficiency is further investigated, providing valuable guidelines for enhancing the tuning efficiency of the graphene microheater. PMID:28181531

  19. Monitoring of degradation of porous silicon photonic crystals using digital photography

    Science.gov (United States)

    2014-01-01

    We report the monitoring of porous silicon (pSi) degradation in aqueous solutions using a consumer-grade digital camera. To facilitate optical monitoring, the pSi samples were prepared as one-dimensional photonic crystals (rugate filters) by electrochemical etching of highly doped p-type Si wafers using a periodic etch waveform. Two pSi formulations, representing chemistries relevant for self-reporting drug delivery applications, were tested: freshly etched pSi (fpSi) and fpSi coated with the biodegradable polymer chitosan (pSi-ch). Accelerated degradation of the samples in an ethanol-containing pH 10 aqueous basic buffer was monitored in situ by digital imaging with a consumer-grade digital camera with simultaneous optical reflectance spectrophotometric point measurements. As the nanostructured porous silicon matrix dissolved, a hypsochromic shift in the wavelength of the rugate reflectance peak resulted in visible color changes from red to green. While the H coordinate in the hue, saturation, and value (HSV) color space calculated using the as-acquired photographs was a good monitor of degradation at short times (t  pSi-ch. PMID:25242902

  20. Performance of a PET detector module utilizing an array of silicon photodiodes to identify the crystal of interaction

    International Nuclear Information System (INIS)

    Moses, W.W.; Derenzo, S.E.; Nutt, R.; Digby, W.M.; Williams, C.W.; Andreaco, M.

    1993-01-01

    The authors initial performance results for a new multi-layer PET detector module consisting of an array of 3 mm square by 30 mm deep BGO crystals coupled on one end to a single photomultiplier tube and on the opposite end to an array of 3 mm square silicon photodiodes. The photomultiplier tube provides an accurate timing pulse and energy discrimination for all the crystals in the module, while the silicon photodiodes identify the crystal of interaction. When a single BGO crystal at +25 C is excited with 511 keV photons, the authors measure a photodiode signal centered at 700 electrons (e - ) with noise of 375 e - fwhm. When a four crystal/photodiode module is excited with a collimated line source of 511 keV photons, the crystal of interaction is correctly identified 82% of the time. The misidentification rate can be greatly reduced and an 8 x 8 crystal/photodiode module constructed by using thicker depletion layer photodiodes or cooling to 0 C

  1. Polarized photons from a silicon crystal in a 31 GeV electron beam at the Serpukhov proton accelerator

    International Nuclear Information System (INIS)

    Frolov, A.M.; Maisheev, V.A.; Arakelyan, E.A.; Armaganyan, A.A.; Avakyan, R.O.; Bayatyan, G.L.; Grigoryan, N.K.; Kechechyan, A.O.; Knyazyan, S.G.; Margaryan, A.T.

    1980-01-01

    Tagged photons coherently emitted in a silicon crystal by the 31 GeV electron beam of intensity 4 x 10 4 ppp and beam pulse duration of up to 1.7 s have been obtained at the Serpukhov proton accelerator. The photon intensities were I approx. 10 -1 - 10 -2 γ/e - in five almost equal energy bins within the total range k = (8.2-24.2) GeV. The calculated linear polarizations were P approx. 50-20%, respectively. Narrow peaks in the radiation intensity were observed when varying the orientation of a silicon crystal which could not be explained. The method for the experimental alignment of a crystal in electron beams at the proton accelerator has been described. (orig.)

  2. A phononic crystal strip based on silicon for support tether applications in silicon-based MEMS resonators and effects of temperature and dopant on its band gap characteristics

    Directory of Open Access Journals (Sweden)

    Thi Dep Ha

    2016-04-01

    Full Text Available Phononic crystals (PnCs and n-type doped silicon technique have been widely employed in silicon-based MEMS resonators to obtain high quality factor (Q as well as temperature-induced frequency stability. For the PnCs, their band gaps play an important role in the acoustic wave propagation. Also, the temperature and dopant doped into silicon can cause the change in its material properties such as elastic constants, Young’s modulus. Therefore, in order to design the simultaneous high Q and frequency stability silicon-based MEMS resonators by two these techniques, a careful design should study effects of temperature and dopant on the band gap characteristics to examine the acoustic wave propagation in the PnC. Based on these, this paper presents (1 a proposed silicon-based PnC strip structure for support tether applications in low frequency silicon-based MEMS resonators, (2 influences of temperature and dopant on band gap characteristics of the PnC strips. The simulation results show that the largest band gap can achieve up to 33.56 at 57.59 MHz and increase 1280.13 % (also increase 131.89 % for ratio of the widest gaps compared with the counterpart without hole. The band gap properties of the PnC strips is insignificantly effected by temperature and electron doping concentration. Also, the quality factor of two designed length extensional mode MEMS resonators with proposed PnC strip based support tethers is up to 1084.59% and 43846.36% over the same resonators with PnC strip without hole and circled corners, respectively. This theoretical study uses the finite element analysis in COMSOL Multiphysics and MATLAB softwares as simulation tools. This findings provides a background in combination of PnC and dopant techniques for high performance silicon-based MEMS resonators as well as PnC-based MEMS devices.

  3. A phononic crystal strip based on silicon for support tether applications in silicon-based MEMS resonators and effects of temperature and dopant on its band gap characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Thi Dep, E-mail: hathidep@yahoo.com [School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731 (China); Faculty of Electronic Technology, Industrial University of Ho Chi Minh City, Hochiminh City (Viet Nam); Bao, JingFu, E-mail: baojingfu@uestc.edu.cn [School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731 (China)

    2016-04-15

    Phononic crystals (PnCs) and n-type doped silicon technique have been widely employed in silicon-based MEMS resonators to obtain high quality factor (Q) as well as temperature-induced frequency stability. For the PnCs, their band gaps play an important role in the acoustic wave propagation. Also, the temperature and dopant doped into silicon can cause the change in its material properties such as elastic constants, Young’s modulus. Therefore, in order to design the simultaneous high Q and frequency stability silicon-based MEMS resonators by two these techniques, a careful design should study effects of temperature and dopant on the band gap characteristics to examine the acoustic wave propagation in the PnC. Based on these, this paper presents (1) a proposed silicon-based PnC strip structure for support tether applications in low frequency silicon-based MEMS resonators, (2) influences of temperature and dopant on band gap characteristics of the PnC strips. The simulation results show that the largest band gap can achieve up to 33.56 at 57.59 MHz and increase 1280.13 % (also increase 131.89 % for ratio of the widest gaps) compared with the counterpart without hole. The band gap properties of the PnC strips is insignificantly effected by temperature and electron doping concentration. Also, the quality factor of two designed length extensional mode MEMS resonators with proposed PnC strip based support tethers is up to 1084.59% and 43846.36% over the same resonators with PnC strip without hole and circled corners, respectively. This theoretical study uses the finite element analysis in COMSOL Multiphysics and MATLAB softwares as simulation tools. This findings provides a background in combination of PnC and dopant techniques for high performance silicon-based MEMS resonators as well as PnC-based MEMS devices.

  4. Performance study of Philips digital silicon photomultiplier coupled to scintillating crystals

    CERN Document Server

    Liu, Z.; Auffray, E.; Lecoq, P.; Paganoni, M.

    2016-01-01

    Silicon photomultipliers (SiPMs) and scintillators are often arranged in the shape of arrays in Positron Emission Tomography (PET) systems. Digital SiPMs provide signal readout in single photon avalanche diode (SPAD) level. From the photon count rate measurement of each SPAD cell of digital SiPM, we found that the output scintillating photons distribute in an area larger than the scintillator physical coupling area. Taking advantage of the possibility to enable/disable individual cells of the digital SiPM, a group of Lutetium-yttrium oxyorthosilicate (LYSO) crystals with different dimensions coupled to a digital SiPM was used to study the influence of using different SiPM active area on the number of photons detected, energy resolution and coincidence time resolution (CTR). For the same crystal coupled to the digital SiPM, the larger the active area of digital SiPM, the higher the number of photons detected. The larger active area of the digital SiPM also results in a better energy resolution after saturation...

  5. Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Minkyu; Seo, Jung-Hun; Lee, Jaeseong; Mi, Hongyi; Kim, Munho; Ma, Zhenqiang, E-mail: mazq@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Zhao, Deyin; Zhou, Weidong [Nanophotonics Lab, Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yin, Xin; Wang, Xudong [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-05-04

    In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO{sub 2} and thus a Si/SiO{sub 2} pair with uniform and precisely controlled thicknesses. The Si/SiO{sub 2} layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.

  6. Insight into excimer laser crystallization exploiting ellipsometry: Effect of silicon film precursor

    Energy Technology Data Exchange (ETDEWEB)

    Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)], E-mail: maria.losurdo@ba.imip.cnr.it; Giangregorio, Maria M.; Sacchetti, Alberto; Capezzuto, Pio; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy); Mariucci, Luigi; Fortunato, Guglielmo [IFN-CNR, Via Cineto Romano, 42 - 00156 Rome (Italy)

    2007-07-16

    The optical diagnostic of spectroscopic ellipsometry is shown to be an effective tool to investigate the mechanism of excimer laser crystallization (ELC) of silicon thin films. A detailed spectroscopic ellipsometric investigation of the microstructures of polycrystalline Si films obtained on SiO{sub 2}/Si wafers by ELC of a-Si:H and nc-Si films deposited, respectively, by SiH{sub 4} plasma enhanced chemical vapor deposition (PECVD) and SiF{sub 4}-PECVD is presented. It is shown that ellipsometric spectra of the pseudodielectric function of polysilicon thin films allows to discern the three different ELC regimes of partial melting, super lateral growth and complete melting. Exploiting ellipsometry and atomic force microscopy, it is shown that ELC of nc-Si has very low energy density threshold of 95 mJ/cm{sup 2} for complete melting, and that re-crystallization to large grains of {approx} 2 {mu}m can be achieved by multi-shot irradiation at an energy density as low as 260 mJ/cm{sup 2} when using nc-Si when compared to 340 mJ/cm{sup 2} for the ELC of a-Si films.

  7. Silicone Stent Placement for Primary Tracheal Amyloidosis Accompanied by Cartilage Destruction

    OpenAIRE

    Ryu, Duck Hyun; Eom, Jung Seop; Jeong, Ho Jung; Kim, Jung Hoon; Lee, Ji Eun; Jun, Ji Eun; Song, Dae Hyun; Han, Joungho; Kim, Hojoong

    2014-01-01

    Primary tracheal amyloidosis (PTA) can lead to airway obstructions, and patients with severe PTA should undergo bronchoscopic interventions in order to maintain airway patency. Focal airway involvements with amyloidosis can only be treated with mechanical dilatation. However, the PTA with diffused airway involvements and concomitant cartilage destructions requires stent placement. Limited information regarding the usefulness of silicone stents in patients with PTA has been released. Therefore...

  8. Apparent temperature versus true temperature of silicon crystals as a function of their thickness using infrared measurements

    International Nuclear Information System (INIS)

    Smither, R.K.; Fernandez, P.B.

    1993-01-01

    The very high intensity x-ray beams that will be present at the Advanced Photon Source and other third generation synchrotron sources will require that the first optical element in the beamline and, possibly, the second optical element as well, be cooled to remove the heat deposited by the x-ray beam. In many of the beamlines this heat will be in the 1 to 5 kW range, and any failure of the cooling system will require a quick response from safety control circuits to shut off the beam before damage is done to the optical element. In many cases, this first optical element will be a silicon diffraction crystal. Viewing the surface of objects subjected to high heat fluxes with an infrared camera or infrared sensor has proved to be a very effective method for monitoring the magnitude and distribution of surface temperatures on the object. This approach has been quite useful in studies of cooling silicon crystals in monochromators subject to high heat loads. The main drawback to this method is that single crystals of silicon are partially transparent to the infrared radiation monitored in most infrared cameras. This means that the infrared radiation emitted from the surface contains a component that comes from the interior of the crystal and that the intensity of the emitted radiation and thus the apparent temperature of the surface of the crystal depends on the thickness of the crystal and the kind of coating on the back (and/or the front) of the crystal. The apparent temperature of the crystal increases as the crystal is made thicker. A series of experiments were performed at Argonne National Laboratory to calibrate the apparent surface temperature of the crystal as measured with an infrared camera as a function of the crystal thickness and the type of coating (if any) on the back side of the crystal. A number of examples are given for data taken in synchrotron experiments with high intensity x-ray beams

  9. Monte Carlo calculation of energy loss of hydrogen and helium ions transmitted under channelling conditions in silicon single crystal

    International Nuclear Information System (INIS)

    El Bounagui, O.; Erramli, H.

    2010-01-01

    In this work, we report on calculations of the electronic channelling energy loss of hydrogen and helium ions along Si and Si axial directions for the low energy range by using the Monte Carlo simulation code. Simulated and experimental data are compared for protons and He ions in the and axis of silicon. A reasonable agreement was found. Computer simulation was also employed to study the angular dependence of energy loss for 0.5, 0.8, 1, and 2 MeV channelled 4 He ions transmitted through a silicon crystal of 3 μm thickness along the axis.

  10. Cross two photon absorption in a silicon photonic crystal waveguide fiber taper coupler with a physical junction

    Energy Technology Data Exchange (ETDEWEB)

    Sarkissian, Raymond, E-mail: RaymondSark@gmail.com; O' Brien, John [Electrophysics department, University of Southern California, Los Angeles, California 90089 (United States)

    2015-01-21

    Cross two photon absorption in silicon is characterized using a tapered fiber photonic crystal silicon waveguide coupler. There is a physical junction between the tapered fiber and the waveguide constituting a stand-alone device. This device is used to obtain the spectrum for cross two photon absorption coefficient per unit volume of interaction between photons of nondegenerate energy. The corresponding Kerr coefficient per unit volume of interaction is also experimentally extracted. The thermal resistance of the device is also experimentally determined and the response time of the device is estimated for on-chip all-optical signal processing and data transfer between optical signals of different photon energies.

  11. Double and triple crystal diffraction investigation on ion implanted and electron beam annealed silicon

    International Nuclear Information System (INIS)

    Servidori, M.; Cembali, F.; Winter, U.; Zaumseil, P.; Richter, H.

    1985-01-01

    Double (DCD) and triple crystal (TCD) diffractometry was used to investigate radiation damage produced in silicon by silicon bombardment and its evolution after electron beam annealing. The implantation processes were carried out at 60 keV energy and at doses of 0.5, 1, 5, 10, 50, 100, and 200 x 10 13 ions/cm 2 . As to the annealing treatments, an electron gun was used, operating in the ranges 7.5 to 24 W/cm 2 and 2 to 20 seconds. DCD rocking curves were analyzed by means of the dynamical theory of X-ray diffraction. The formalism introduced by Taupin was used to simulate the experimental intensity profiles. From the resulting best fits, the lattice strain vs. depth profiles were obtained, indicating an increase of the damage with dose for the as-implanted samples up to 1 x 10 14 cm -2 dose, whereas amorphous layers are produced for the higher doses. After annealing, lowering of the residual strain was observed to be directly proportional to the implanted dose. In particular, a complete recovery of the damage occurred for the 0.5 and 1 x 10 13 cm -2 samples. The results obtained by the fitting procedure were substantially independent from the power densities and times used during electron beam irradiation. TCD as a very sensitive method to investigate lattice defects after implantation was used to obtain information about the crystallographic perfection of the surface layer. The absence of diffuse scattering indicates that the annealed layers do not contain microdefects within the detection limits. (author)

  12. Detached Bridgman Growth of Germanium and Germanium-Silicon Alloy Crystals

    Science.gov (United States)

    Szofran, F. R.; Volz, M. P.; Schweizer, M.; Cobb, S. D.; Motakef, S.; Croell, A.; Dold, P.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Earth based experiments on the science of detached crystal growth are being conducted on germanium and germanium-silicon alloys (2 at% Si average composition) in preparation for a series of experiments aboard the International Space Station (ISS). The purpose of the microgravity experiments includes differentiating among proposed mechanisms contributing to detachment, and confirming or refining our understanding of the detachment mechanism. Because large contact angle are critical to detachment, sessile drop measurements were used to determine the contact angles as a function of temperature and composition for a large number of substrates made of potential ampoule materials. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. The contact angles were 173 deg (Ge) and 165 deg (GeSi) for pBN. For fused silica, the contact angle decreases from 150 deg to an equilibrium value of 117 deg (Ge) or from 129 deg to an equilibrium value of 100 deg (GeSi) over the duration of the experiment. The nature and extent of detachment is determined by using profilometry in conjunction with optical and electron microscopy. The stability of detachment has been analyzed, and an empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed. Results in this presentation will show that we have established the effects on detachment of ampoule material, pressure difference above and below the melt, and silicon concentration; samples that are nearly completely detached can be grown repeatedly in pBN.

  13. Friction and Wear of Metals With a Single-Crystal Abrasive Grit of Silicon Carbide - Effect of Shear Strength of Metal

    National Research Council Canada - National Science Library

    Miyoshi, Kazuhisa

    1978-01-01

    An investigation was conducted to examine the removal and plastic deformation of metal as a function of the metal properties when the metal is in sliding contact with a single-crystal abrasive grit of silicon carbide...

  14. Numerical and experimental study of a solid pellet feed continuous Czochralski growth process for silicon single crystals

    Science.gov (United States)

    Anselmo, A.; Prasad, V.; Koziol, J.; Gupta, K. P.

    1993-07-01

    A polysilicon pellets (≅1 mm diameter) feed continuous Czochralski (CCZ) growth process for silicon single crystals is proposed and investigated. Experiments in an industrial puller (14-18 inch diameter crucible) successfully demonstrate the feasibility of this process. The advantages of the proposed scheme are: a steady state growth process, a low aspect ratio melt, uniformity of heat addition and a growth apparatus with single crucible and no baffle(s). The addition of dopant with the solid charge will allow a better control of oxygen concentration leading to crystals of uniform properties and better quality. This paper presents theoretical results on melting of fully and partially immersed silicon spheres and numerical solutions on temperature and flow fields in low aspect ration melts with and without the addition of solid pellets. The theoretical and experimental results obtained thus far show a great promise for the proposed scheme.

  15. Proceedings of the Flat-Plate Solar Array Project Workshop on Crystal Gowth for High-Efficiency Silicon Solar Cells

    Science.gov (United States)

    Dumas, K. A. (Editor)

    1985-01-01

    A Workshop on Crystal Growth for High-Efficiency Silicon Solar Cells was held December 3 and 4, 1984, in San Diego, California. The Workshop offered a day and a half of technical presentations and discussions and an afternoon session that involved a panel discussion and general discussion of areas of research that are necessary to the development of materials for high-efficiency solar cells. Topics included the theoretical and experimental aspects of growing high-quality silicon crystals, the effects of growth-process-related defects on photovoltaic devices, and the suitability of various growth technologies as cost-effective processes. Fifteen invited papers were presented, with a discussion period following each presentation. The meeting was organized by the Flat-Plate Solar Array Project of the Jet Propulsion Laboratory. These Proceedings are a record of the presentations and discussions, edited for clarity and continuity.

  16. Self-supporting film method of silicon single crystal by ion implantation and it`s application

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kazuo; Nakao, Setsuo; Niwa, Hiroaki; Miyagawa, Soji [National Industrial Research Inst. of Nagoya (Japan)

    1996-12-01

    A few {mu}m of thickness of self-supporting film of silicon single crystal was produced by the ion implantation and the selective etching. This materials are distinguished by a uniform film thickness, good controllability, crystallization and the mechanical strength. For applying it to device, the detailed process has to be established, because there are some improved problems such as pinhole and morphology on the surface. This materials are very useful to the basic experiment of the base for epitaxial growth under irradiation of ion beams and the ion beam analysis in the atmosphere. (S.Y.)

  17. Glass-embedded two-dimensional silicon photonic crystal devices with a broad bandwidth waveguide and a high quality nanocavity.

    Science.gov (United States)

    Jeon, Seung-Woo; Han, Jin-Kyu; Song, Bong-Shik; Noda, Susumu

    2010-08-30

    To enhance the mechanical stability of a two-dimensional photonic crystal slab structure and maintain its excellent performance, we designed a glass-embedded silicon photonic crystal device consisting of a broad bandwidth waveguide and a nanocavity with a high quality (Q) factor, and then fabricated the structure using spin-on glass (SOG). Furthermore, we showed that the refractive index of the SOG could be tuned from 1.37 to 1.57 by varying the curing temperature of the SOG. Finally, we demonstrated a glass-embedded heterostructured cavity with an ultrahigh Q factor of 160,000 by adjusting the refractive index of the SOG.

  18. Analysis about diamond tool wear in nano-metric cutting of single crystal silicon using molecular dynamics method

    Science.gov (United States)

    Wang, Zhiguo; Liang, Yingchun; Chen, Mingjun; Tong, Zhen; Chen, Jiaxuan

    2010-10-01

    Tool wear not only changes its geometry accuracy and integrity, but also decrease machining precision and surface integrity of workpiece that affect using performance and service life of workpiece in ultra-precision machining. Scholars made a lot of experimental researches and stimulant analyses, but there is a great difference on the wear mechanism, especially on the nano-scale wear mechanism. In this paper, the three-dimensional simulation model is built to simulate nano-metric cutting of a single crystal silicon with a non-rigid right-angle diamond tool with 0 rake angle and 0 clearance angle by the molecular dynamics (MD) simulation approach, which is used to investigate the diamond tool wear during the nano-metric cutting process. A Tersoff potential is employed for the interaction between carbon-carbon atoms, silicon-silicon atoms and carbon-silicon atoms. The tool gets the high alternating shear stress, the tool wear firstly presents at the cutting edge where intension is low. At the corner the tool is splitted along the {1 1 1} crystal plane, which forms the tipping. The wear at the flank face is the structure transformation of diamond that the diamond structure transforms into the sheet graphite structure. Owing to the tool wear the cutting force increases.

  19. GROWTH OF CRYSTALS OF PRIMARY ALUMINIUM WITH ROSETTE MORPHOLOGY AT CASTING OF SILUMINS

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2011-01-01

    Full Text Available The work is devoted to actual theme of alloy solidifi – investigation of infl of overlapping of thermal and concentration fi of neighboring crystals to forming of non- dendrite structures. Experimental research of microstructure of Al-Si alloy for wide range of silicon concentration is conducted, and corresponding numerical simulation develop too. The conclusion about different schemes of forming of rosette structures is adopted.

  20. Primary crystallization in Al-rich metallic glasses at unusually low temperatures

    International Nuclear Information System (INIS)

    Bokeloh, J.; Boucharat, N.; Roesner, H.; Wilde, G.

    2010-01-01

    The initial stage of the primary crystallization reaction and the glass transition of the marginal metallic glass Al 89 Y 6 Fe 5 were investigated by conventional differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC), microcalorimetry, X-ray diffraction (XRD) and transmission electron microscopy. A sharp onset of the primary crystallization was found by microcalorimetry and XRD studies at temperatures which were 120 deg. C below the primary crystallization peak observed in conventional DSC. A systematic MDSC study of annealed samples revealed a wide spectrum of glass transition onsets, which show a strong dependence on the annealing conditions. In addition, the glass transition onsets can be linked to the initial stage of the primary crystallization. The spectrum of glass transition onsets observed is discussed with respect to the occurrence of phase separation preceding the nucleation and growth of dendritic aluminium nanocrystals.

  1. Synchrotron Topographic and Diffractometer Studies of Buried Layered Structures Obtained by Implantation with Swift Heavy Ions in Silicon Single Crystals

    International Nuclear Information System (INIS)

    Wierzchowski, W.; Wieteska, K.; Zymierska, D.; Graeff, W.; Czosnyka, T.; Choinski, J.

    2006-01-01

    A distribution of crystallographic defects and deformation in silicon crystals subjected to deep implantation (20-50 μm) with ions of the energy of a few MeV/amu is studied. Three different buried layered structures (single layer, binary buried structure and triple buried structure) were obtained by implantation of silicon single crystals with 184 MeV argon ions, 29.7 MeV boron ions, and 140 MeV argon ions, each implantation at a fluency of 1x10 14 ions cm -2 . The implanted samples were examined by means of white beam X-ray section and projection topography, monochromatic beam topography and by recording local rocking curves with the beam restricted to 50 x 50 μm 2 . The experiment pointed to a very low level of implantation-induced strain (below 10 -5 ). The white beam Bragg case section experiment revealed a layer producing district black contrast located at a depth of the expected mean ion range. The presence of these buried layered structures in studied silicon crystals strongly affected the fringe pattern caused by curvature of the samples. In case of white beam projection and monochromatic beam topographs the implanted areas were revealed as darker regions with a very tiny grain like structure. One may interpret these results as the effect of considerable heating causing annihilation of point defects and formation of dislocation loops connected with point defect clusters. (author)

  2. Helium interaction with vacancy-type defects created in silicon carbide single crystal

    Science.gov (United States)

    Linez, F.; Gilabert, E.; Debelle, A.; Desgardin, P.; Barthe, M.-F.

    2013-05-01

    Generation of He bubbles or cavities in silicon carbide is an important issue for the use of this material in nuclear and electronic applications. To understand the mechanisms prior to the growth of these structures, an atomic-scale study has been conducted. 6H-SiC single crystals have been implanted with 50 keV-He ions at 2 × 1014 and 1015 cm-2 and successively annealed at various temperatures from 150 to 1400 °C. After each annealing, the defect distributions in the samples have been probed by positron annihilation spectroscopy. Four main evolution stages have been evidenced for the two investigated implantation fluences: at (1) 400 °C for both fluences, (2) at 850 °C for the low fluence and 950 °C for the high one, (3) at 950 °C for the low fluence and 1050 °C for the high one and (4) at 1300 °C for both fluences. The perfect correlation between the positron annihilation spectroscopy and the thermodesorption measurements has highlighted the He involvement in the first two stages corresponding respectively to its trapping by irradiation-induced divacancies and the detrapping from various vacancy-type defects generated by agglomeration processes.

  3. Helium interaction with vacancy-type defects created in silicon carbide single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Linez, F., E-mail: florence.linez@aalto.fi [CEMHTI CNRS, 3A rue de la Férollerie, 45071 Orléans (France); Gilabert, E. [CENBG, U.R.A. 451 CNRS, Université de Bordeaux I, BP120, Le Haut Vigneau, 33175 Gradignan Cedex (France); Debelle, A. [CSNSM, Univ. Paris-Sud, CNRS-IN2P3, 91405 Orsay Campus (France); Desgardin, P.; Barthe, M.-F. [CEMHTI CNRS, 3A rue de la Férollerie, 45071 Orléans (France)

    2013-05-15

    Generation of He bubbles or cavities in silicon carbide is an important issue for the use of this material in nuclear and electronic applications. To understand the mechanisms prior to the growth of these structures, an atomic-scale study has been conducted. 6H–SiC single crystals have been implanted with 50 keV-He ions at 2 × 10{sup 14} and 10{sup 15} cm{sup −2} and successively annealed at various temperatures from 150 to 1400 °C. After each annealing, the defect distributions in the samples have been probed by positron annihilation spectroscopy. Four main evolution stages have been evidenced for the two investigated implantation fluences: at (1) 400 °C for both fluences, (2) at 850 °C for the low fluence and 950 °C for the high one, (3) at 950 °C for the low fluence and 1050 °C for the high one and (4) at 1300 °C for both fluences. The perfect correlation between the positron annihilation spectroscopy and the thermodesorption measurements has highlighted the He involvement in the first two stages corresponding respectively to its trapping by irradiation-induced divacancies and the detrapping from various vacancy-type defects generated by agglomeration processes.

  4. Meshed doped silicon photonic crystals for manipulating near-field thermal radiation

    Science.gov (United States)

    Elzouka, Mahmoud; Ndao, Sidy

    2018-01-01

    The ability to control and manipulate heat flow is of great interest to thermal management and thermal logic and memory devices. Particularly, near-field thermal radiation presents a unique opportunity to enhance heat transfer while being able to tailor its characteristics (e.g., spectral selectivity). However, achieving nanometric gaps, necessary for near-field, has been and remains a formidable challenge. Here, we demonstrate significant enhancement of the near-field heat transfer through meshed photonic crystals with separation gaps above 0.5 μm. Using a first-principle method, we investigate the meshed photonic structures numerically via finite-difference time-domain technique (FDTD) along with the Langevin approach. Results for doped-silicon meshed structures show significant enhancement in heat transfer; 26 times over the non-meshed corrugated structures. This is especially important for thermal management and thermal rectification applications. The results also support the premise that thermal radiation at micro scale is a bulk (rather than a surface) phenomenon; the increase in heat transfer between two meshed-corrugated surfaces compared to the flat surface (8.2) wasn't proportional to the increase in the surface area due to the corrugations (9). Results were further validated through good agreements between the resonant modes predicted from the dispersion relation (calculated using a finite-element method), and transmission factors (calculated from FDTD).

  5. Single-crystal-silicon-based microinstrument to study friction and wear at MEMS sidewall interfaces

    International Nuclear Information System (INIS)

    Ansari, N; Ashurst, W R

    2012-01-01

    Since the advent of microelectromechanical systems (MEMS) technology, friction and wear are considered as key factors that determine the lifetime and reliability of MEMS devices that contain contacting interfaces. However, to date, our knowledge of the mechanisms that govern friction and wear in MEMS is insufficient. Therefore, systematically investigating friction and wear at MEMS scale is critical for the commercial success of many potential MEMS devices. Specifically, since many emerging MEMS devices contain more sidewall interfaces, which are topographically and chemically different from in-plane interfaces, studying the friction and wear characteristics of MEMS sidewall surfaces is important. The microinstruments that have been used to date to investigate the friction and wear characteristics of MEMS sidewall surfaces possess several limitations induced either by their design or the structural film used to fabricate them. Therefore, in this paper, we report on a single-crystal-silicon-based microinstrument to study the frictional and wear behavior of MEMS sidewalls, which not only addresses some of the limitations of other microinstruments but is also easy to fabricate. The design, modeling and fabrication of the microinstrument are described in this paper. Additionally, the coefficients of static and dynamic friction of octadecyltrichlorosilane-coated sidewall surfaces as well as sidewall surfaces with only native oxide on them are also reported in this paper. (paper)

  6. Ultrafast all-optical order-to-chaos transition in silicon photonic crystal chips

    KAUST Repository

    Bruck, Roman

    2016-06-08

    The interaction of light with nanostructured materials provides exciting new opportunities for investigating classical wave analogies of quantum phenomena. A topic of particular interest forms the interplay between wave physics and chaos in systems where a small perturbation can drive the behavior from the classical to chaotic regime. Here, we report an all-optical laser-driven transition from order to chaos in integrated chips on a silicon photonics platform. A square photonic crystal microcavity at telecom wavelengths is tuned from an ordered into a chaotic regime through a perturbation induced by ultrafast laser pulses in the ultraviolet range. The chaotic dynamics of weak probe pulses in the near infrared is characterized for different pump-probe delay times and at various positions in the cavity, with high spatial accuracy. Our experimental analysis, confirmed by numerical modelling based on random matrices, demonstrates that nonlinear optics can be used to control reversibly the chaotic behavior of light in optical resonators. (Figure presented.) . © 2016 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  7. Photonic molecules for improving the optical response of macroporous silicon photonic crystals for gas sensing purposes.

    Science.gov (United States)

    Cardador, D; Segura, D; Rodríguez, A

    2018-02-19

    In this paper, we report the benefits of working with photonic molecules in macroporous silicon photonic crystals. In particular, we theoretically and experimentally demonstrate that the optical properties of a resonant peak produced by a single photonic atom of 2.6 µm wide can be sequentially improved if a second and a third cavity of the same length are introduced in the structure. As a consequence of that, the base of the peak is reduced from 500 nm to 100 nm, while its amplitude remains constant, increasing its Q-factor from its initial value of 25 up to 175. In addition, the bandgap is enlarged almost twice and the noise within it is mostly eliminated. In this study we also provide a way of reducing the amplitude of one or two peaks, depending whether we are in the two- or three-cavity case, by modifying the length of the involved photonic molecules so that the remainder can be used to measure gas by spectroscopic methods.

  8. Crystallization of silicon films of submicron thickness by blue-multi-laser-diode annealing

    Energy Technology Data Exchange (ETDEWEB)

    Mugiraneza, Jean de Dieu; Shirai, Katsuya; Suzuki, Toshiharu; Okada, Tatsuya; Noguchi, Takashi [University of the Ryukyus, Okinawa (Japan); Matsushima, Hideki; Hashimoto, Takao; Ogino, Yoshiaki; Sahota, Eiji [Hitachi Computer Peripherals Co. Ltd, Kanagawa (Japan)

    2012-01-15

    Blue-Multi-Laser-Diode Annealing (BLDA) was performed in the continuous wave (CW) mode on Si films as thick as 0.5 {mu}m and 1 {mu}m deposited by rf sputtering. As a result of controlling the laser power from 4.0 to 4.8 W, a whole Si layer of 0.5 {mu}m in thickness was completely crystallized and consisted of a columnar structure of fine grains beneath a partially melted Si surface owing to the high temperature gradient along the depth in the Si layer. After additional hydrogenation in a furnace ambient, the ratio of the photo/dark current under AM 1.5 illumination distinctly improved to 6 times higher than that of as-deposited condition. The BLDA is expected to be applied to thin-film solar cells and/or to thin film transistor (TFT) photo-sensor systems on panels as a new low-temperature poly-silicon (LTPS) fabrication technique.

  9. Supercontinuum generation in silicon nanowire embedded photonic crystal fibers with different core geometries

    Science.gov (United States)

    Abdosllam, M. Abobaker; Gunasundari, E.; Senthilnathan, K.; Sivabalan, S.; Nakkeeran, K.; Ramesh Babu, P.

    2014-07-01

    We design various silicon nanowire embedded photonic crystal fibers (SN-PCFs) with different core geometries, namely, circular, rectangular and elliptical using finite element method. Further, we study the optical properties such as group velocity dispersion (GVD), third order dispersion (TOD) of x and y-polarized modes and effective nonlinearity for a wavelength range from 0.8 to 1.6 μm. The proposed structure exhibits almost flat GVD (0.8 to 1.2 μm wavelength), zero GVD (≍ 1.31 μm) and small TOD (0.00069 ps3/m) at 1.1 μm wavelength and high nonlinearity (2916 W-1m-1) at 0.8 μm wavelength for a 300 nm core diameter of circular core SN-PCF. Besides, we have been able to demonstrate the supercontinuum for the different core geometries at 1.3 μm wavelength with a less input power of 25 W for the input pulse of 20 fs. The numerical simulation results reveal that the proposed circular core SN-PCF could generate the supercontinuum of wider bandwidth (900 nm) compared to that from rest of the geometries. This enhanced bandwidth turns out to be a boon for optical coherence tomography (OCT) system.

  10. Optical design of ultrashort throw liquid crystal on silicon projection system

    Science.gov (United States)

    Huang, Jiun-Woei

    2017-05-01

    An ultrashort throw liquid crystal on silicon (LCoS) projector for home cinema, virtual reality, and automobile heads-up display has been designed and fabricated. To achieve the best performance and highest-quality image, this study aimed to design wide-angle projection optics and optimize the illumination for LCoS. Based on the telecentric lens projection system and optimized Koehler illumination, the optical parameters were calculated. The projector's optical system consisted of a conic aspheric mirror and image optics using either symmetric double Gauss or a large-angle eyepiece to achieve a full projection angle larger than 155 deg. By applying Koehler illumination, image resolution was enhanced and the modulation transfer function of the image in high spatial frequency was increased to form a high-quality illuminated image. The partial coherence analysis verified that the design was capable of 2.5 lps/mm within a 2 m×1.5 m projected image. The throw ratio was less than 0.25 in HD format.

  11. Simulated human eye retina adaptive optics imaging system based on a liquid crystal on silicon device

    International Nuclear Information System (INIS)

    Jiang Baoguang; Cao Zhaoliang; Mu Quanquan; Hu Lifa; Li Chao; Xuan Li

    2008-01-01

    In order to obtain a clear image of the retina of model eye, an adaptive optics system used to correct the wave-front error is introduced in this paper. The spatial light modulator that we use here is a liquid crystal on a silicon device instead of a conversional deformable mirror. A paper with carbon granule is used to simulate the retina of human eye. The pupil size of the model eye is adjustable (3-7 mm). A Shack–Hartman wave-front sensor is used to detect the wave-front aberration. With this construction, a value of peak-to-valley is achieved to be 0.086 λ, where λ is wavelength. The modulation transfer functions before and after corrections are compared. And the resolution of this system after correction (691p/m) is very close to the dirraction limit resolution. The carbon granule on the white paper which has a size of 4.7 μm is seen clearly. The size of the retina cell is between 4 and 10 mu;m. So this system has an ability to image the human eye's retina. (classical areas of phenomenology)

  12. Two-dimensionally grown single-crystal silicon nanosheets with tunable visible-light emissions.

    Science.gov (United States)

    Kim, Sung Wook; Lee, Jaejun; Sung, Ji Ho; Seo, Dong-jae; Kim, Ilsoo; Jo, Moon-Ho; Kwon, Byoung Wook; Choi, Won Kook; Choi, Heon-Jin

    2014-07-22

    Since the discovery of graphene, growth of two-dimensional (2D) nanomaterials has greatly attracted attention. However, spontaneous growth of atomic two-dimensional (2D) materials is limitedly permitted for several layered-structure crystals, such as graphene, MoS2, and h-BN, and otherwise it is notoriously difficult. Here we report the gas-phase 2D growth of silicon (Si), that is cubic in symmetry, via dendritic growth and an interdendritic filling mechanism and to form Si nanosheets (SiNSs) of 1 to 13 nm in thickness. Thin SiNSs show strong thickness-dependent photoluminescence in visible range including red, green, and blue (RGB) emissions with the associated band gap energies ranging from 1.6 to 3.2 eV; these emission energies were greater than those from Si quantum dots (SiQDs) of the similar sizes. We also demonstrated that electrically driven white, as well as blue, emission in a conventional organic light-emitting diode (OLED) geometry with the SiNS assembly as the active emitting layers. Tunable light emissions in visible range in our observations suggest practical implications for novel 2D Si nanophotonics.

  13. Piezoresistive pressure sensor using low-temperature aluminium induced crystallization of sputter-deposited amorphous silicon film

    International Nuclear Information System (INIS)

    Tiwari, Ruchi; Chandra, Sudhir

    2013-01-01

    In the present work, we have investigated the piezoresistive properties of silicon films prepared by the radio frequency magnetron sputtering technique, followed by the aluminium induced crystallization (AIC) process. Orientation and grain size of the polysilicon films were studied by x-ray diffraction analysis and found to be in the range 30–50 nm. Annealing of the Al–Si stack on an oxidized silicon substrate was performed in air ambient at 300–550 °C, resulting in layer exchange and transformation from amorphous to polysilicon phase. Van der Pauw and Hall measurement techniques were used to investigate the sheet resistance and carrier mobility of the resulting polycrystalline silicon film. The effect of Al thickness on the sheet resistance and mobility was also studied in the present work. A piezoresistive pressure sensor was fabricated on an oxidized silicon substrate in a Wheatstone bridge configuration, comprising of four piezoresistors made of polysilicon film obtained by the AIC process. The diaphragm was formed by the bulk-micromachining of silicon substrate. The response of the pressure sensor with applied negative pressure in 10–95 kPa range was studied. The gauge factor was estimated to be 5 and 18 for differently located piezoresistors on the diaphragm. The sensitivity of the pressure sensor was measured to be ∼ 30 mV MPa −1 , when the Wheatstone bridge was biased at 1 V input voltage. (paper)

  14. In situ study of the growth and degradation processes in tetragonal lysozyme crystals on a silicon substrate by high-resolution X-ray diffractometry

    Science.gov (United States)

    Kovalchuk, M. V.; Prosekov, P. A.; Marchenkova, M. A.; Blagov, A. E.; D'yakova, Yu. A.; Tereshchenko, E. Yu.; Pisarevskii, Yu. V.; Kondratev, O. A.

    2014-09-01

    The results of an in situ study of the growth of tetragonal lysozyme crystals by high-resolution X-ray diffractometry are considered. The crystals are grown by the sitting-drop method on crystalline silicon substrates of different types: both on smooth substrates and substrates with artificial surface-relief structures using graphoepitaxy. The crystals are grown in a special hermetically closed crystallization cell, which enables one to obtain images with an optical microscope and perform in situ X-ray diffraction studies in the course of crystal growth. Measurements for lysozyme crystals were carried out in different stages of the crystallization process, including crystal nucleation and growth, developed crystals, the degradation of the crystal structure, and complete destruction.

  15. In situ nanoscale refinement by highly controllable etching of the (111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire

    International Nuclear Information System (INIS)

    Gong Yibin; Dai Pengfei; Gao Anran; Li Tie; Zhou Ping; Wang Yuelin

    2011-01-01

    Nanoscale refinement on a (100) oriented silicon-on-insulator (SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide (TMAH, 25 wt%) anisotropic silicon etchant, with temperature kept at 50 °C to achieve precise etching of the (111) crystal plane. Specifically for a silicon nanowire (SiNW) with oxide sidewall protection, the in situ TMAH process enabled effective size reduction in both lateral (2.3 nm/min) and vertical (1.7 nm/min) dimensions. A sub-50 nm SiNW with a length of microns with uniform triangular cross-section was achieved accordingly, yielding enhanced field effect transistor (FET) characteristics in comparison with its 100 nm-wide pre-refining counterpart, which demonstrated the feasibility of this highly controllable refinement process. Detailed examination revealed that the high surface quality of the (111) plane, as well as the bulk depletion property should be the causes of this electrical enhancement, which implies the great potential of the as-made cost-effective SiNW FET device in many fields. (semiconductor materials)

  16. Flash-lamp-crystallized polycrystalline silicon films with high hydrogen concentration formed from Cat-CVD a-Si films

    International Nuclear Information System (INIS)

    Ohdaira, Keisuke; Tomura, Naohito; Ishii, Shohei; Matsumura, Hideki

    2011-01-01

    We investigate residual forms of hydrogen (H) atoms such as bonding configuration in poly-crystalline silicon (poly-Si) films formed by the flash-lamp-induced crystallization of catalytic chemical vapor deposited (Cat-CVD) a-Si films. Raman spectroscopy reveals that at least part of H atoms in flash-lamp-crystallized (FLC) poly-Si films form Si-H 2 bonds as well as Si-H bonds with Si atoms even using Si-H-rich Cat-CVD a-Si films, which indicates the rearrangement of H atoms during crystallization. The peak desorption temperature during thermal desorption spectroscopy (TDS) is as high as 900 o C, similar to the reported value for bulk poly-Si.

  17. Calibration of the apparent temperature of silicon single crystals as a function of their true temperature and their thickness as determined by infrared measurements

    International Nuclear Information System (INIS)

    Smither, R.K.; Fernandez, P.B.

    1993-09-01

    Viewing the surface of objects subjected to high heat fluxes with an infrared camera or infrared sensor has proved to be a very effective method for monitoring the magnitude and distribution of surface temperature on the object. This approach has been quite useful in studies of cooling silicon crystals in monochromators subject to high heat loads. The main drawback to this method is that single crystals of silicon are partially transparent to the infrared radiation monitored in most infrared cameras. This means that the infrared radiation emitted from the surface contains a component that comes from the interior of the crystal and that the intensity of the emitted radiation and thus the apparent temperature of the surface of the crystal depends on the thickness of the crystal and the kind of coating on the back (and/or the front) of the crystal. The apparent temperature of the crystal increases as the crystal is made thicker. A series of experiments were performed at Argonne National Laboratory to calibrate the apparent surface temperature of the crystal as measured with an infrared camera as a function of the crystal thickness and the type of coating (if any) on the back side of the crystal. A good reflecting surface on the back side of the crystal increases the apparent temperature of the crystal and simulates the response of a crystal twice the thickness. These measurements make it possible to interpret the infrared signals from cooled silicon crystals used in past high heat load experiments. A number of examples are given for data taken in synchrotron experiments with high intensity x-ray beams

  18. Ultra-compact and wide-spectrum-range thermo-optic switch based on silicon coupled photonic crystal microcavities

    International Nuclear Information System (INIS)

    Zhang, Xingyu; Chung, Chi-Jui; Pan, Zeyu; Yan, Hai; Chakravarty, Swapnajit; Chen, Ray T.

    2015-01-01

    We design, fabricate, and experimentally demonstrate a compact thermo-optic gate switch comprising a 3.78 μm-long coupled L0-type photonic crystal microcavities on a silicon-on-insulator substrate. A nanohole is inserted in the center of each individual L0 photonic crystal microcavity. Coupling between identical microcavities gives rise to bonding and anti-bonding states of the coupled photonic molecules. The coupled photonic crystal microcavities are numerically simulated and experimentally verified with a 6 nm-wide flat-bottom resonance in its transmission spectrum, which enables wider operational spectrum range than microring resonators. An integrated micro-heater is in direct contact with the silicon core to efficiently drive the device. The thermo-optic switch is measured with an optical extinction ratio of 20 dB, an on-off switching power of 18.2 mW, a thermo-optic tuning efficiency of 0.63 nm/mW, a rise time of 14.8 μs, and a fall time of 18.5 μs. The measured on-chip loss on the transmission band is as low as 1 dB

  19. Solid-phase crystallization of amorphous silicon on ZnO:Al for thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Becker, C.; Conrad, E.; Dogan, P.; Fenske, F.; Gorka, B.; Haenel, T.; Lee, K.Y.; Rau, B.; Ruske, F.; Weber, T.; Gall, S.; Rech, B. [Helmholtz-Zentrum Berlin fuer Materialien und Energie (formerly Hahn-Meitner-Institut Berlin), Kekulestr. 5, D-12489 Berlin (Germany); Berginski, M.; Huepkes, J. [Institute of Photovoltaics, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

    2009-06-15

    The suitability of ZnO:Al thin films for polycrystalline silicon (poly-Si) thin-film solar cell fabrication was investigated. The electrical and optical properties of 700 -nm-thick ZnO:Al films on glass were analyzed after typical annealing steps occurring during poly-Si film preparation. If the ZnO:Al layer is covered by a 30 nm thin silicon film, the initial sheet resistance of ZnO:Al drops from 4.2 to 2.2 {omega} after 22 h annealing at 600 C and only slightly increases for a 200 s heat treatment at 900 C. A thin-film solar cell concept consisting of poly-Si films on ZnO:Al coated glass is introduced. First solar cell results will be presented using absorber layers either prepared by solid-phase crystallization (SPC) or by direct deposition at 600 C. (author)

  20. Structural and electronic characterization of 355 nm laser-crystallized silicon: Interplay of film thickness and laser fluence

    International Nuclear Information System (INIS)

    Semler, Matthew R.; Swenson, Orven F.; Hoey, Justin M.; Guruvenket, Srinivasan; Gette, Cody R.; Hobbie, Erik K.

    2014-01-01

    We present a detailed study of the laser crystallization of amorphous silicon thin films as a function of laser fluence and film thickness. Silicon films grown through plasma-enhanced chemical vapor deposition were subjected to a Q-switched, diode-pumped solid-state laser operating at 355 nm. The crystallinity, morphology, and optical and electronic properties of the films are characterized through transmission and reflectance spectroscopy, resistivity measurements, Raman spectroscopy, X-ray diffraction, atomic force microscopy, and optical and scanning-electron microscopy. Our results reveal a unique surface morphology that strongly couples to the electronic characteristics of the films, with a minimum laser fluence at which the film properties are optimized. A simple scaling model is used to relate film morphology to conductivity in the laser-processed films

  1. Probing the formation of silicon nano-crystals (Si-ncs) using variable energy positron annihilation spectroscopy

    Science.gov (United States)

    Knights, A. P.; Bradley, J. D. B.; Hulko, O.; Stevanovic, D. V.; Edwards, C. J.; Kallis, A.; Coleman, P. G.; Crowe, I. F.; Halsall, M. P.; Gwilliam, R. M.

    2011-01-01

    We describe preliminary results from studies of the formation of silicon nano-crystals (Si-ncs) embedded in stoichiometric, thermally grown SiO2 using Variable Energy Positron Annihilation Spectroscopy (VEPAS). We show that the VEPAS technique is able to monitor the introduction of structural damage. In SiO2 through the high dose Si+ ion implantation required to introduce excess silicon as a precursor to Si-nc formation. VEPAS is also able to characterize the rate of the removal of this damage with high temperature annealing, showing strong correlation with photoluminescence. Finally, VEPAS is shown to be able to selectively probe the interface between Si-ncs and the host oxide. Introduction of hydrogen at these interfaces suppresses the trapping of positrons at the interfaces.

  2. One primary collimator with optional crystal feature, tested with beam

    CERN Document Server

    EuCARD, Collaboration

    2014-01-01

    The WP8 of EuCARD aims at the design of more advanced materials and collimator concepts for high beam power in particle accelerators like LHC and FAIR. Deliverable 8.3.1 concerned the production and the validation by beam tests of an advanced collimator prototype to improve various aspects of the LHC collimation system, such as the accuracy of the collimator jaw alignment to the circulating beam, the duration of collimator setup time and the overall halo cleaning performance. A collimator prototype was built and installed in the SPS for beam tests in the running period between 2010 and 2012. Crystal collimation aspects were dealt with in a dedicated SPS experiment, which also profited from EuCARD contributions.

  3. Microdefects in an as-grown Czochralski silicon crystal studied by synchrotron radiation section topography with aid of computer simulation

    International Nuclear Information System (INIS)

    Iida, Satoshi; Aoki, Yoshirou; Okitsu, Kouhei; Sugita, Yoshimitsu; Kawata, Hiroshi; Abe, Takao

    1998-01-01

    Grown-in microdefects of a Czochralski (CZ) silicon crystal grown at a slow growth rate were studied by section topography using high energy synchrotron radiation. Images of the microdefects in the section topographs were analyzed quantitatively using computer simulation based on the Takagi-Taupin type dynamical diffraction theory of X-rays, and reproduced successfully by the simulation when the microdefects were assumed to be spherical strain centers. Sizes and positions of the microdefects were able to be determined by detailed comparison between the experiments and the computer simulations. The validity of the computer simulation in an analysis of the section topographs is discussed. (author)

  4. A new computationally-efficient two-dimensional model for boron implantation into single-crystal silicon

    International Nuclear Information System (INIS)

    Klein, K.M.; Park, C.; Yang, S.; Morris, S.; Do, V.; Tasch, F.

    1992-01-01

    We have developed a new computationally-efficient two-dimensional model for boron implantation into single-crystal silicon. This paper reports that this new model is based on the dual Pearson semi-empirical implant depth profile model and the UT-MARLOWE Monte Carlo boron ion implantation model. This new model can predict with very high computational efficiency two-dimensional as-implanted boron profiles as a function of energy, dose, tilt angle, rotation angle, masking edge orientation, and masking edge thickness

  5. Lithographic wavelength control of an external cavity laser with a silicon photonic crystal cavity-based resonant reflector.

    Science.gov (United States)

    Liles, Alexandros A; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of a new design for external cavity hybrid lasers consisting of a III-V semiconductor optical amplifier (SOA) with fiber reflector and a photonic crystal (PhC)-based resonant reflector on SOI. The silicon reflector is composed of an SU8 polymer bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and side-mode suppression ratios of more than 25 dB.

  6. Enhanced extraction of silicon-vacancy centers light emission using bottom-up engineered polycrystalline diamond photonic crystal slabs

    Czech Academy of Sciences Publication Activity Database

    Ondič, Lukáš; Varga, Marián; Hruška, Karel; Fait, J.; Kapusta, Peter

    2017-01-01

    Roč. 11, č. 3 (2017), s. 2972-2981 ISSN 1936-0851 R&D Projects: GA ČR GJ16-09692Y; GA MŠk LD15003; GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : photonic crystal * diamond * silicon vacancy center Subject RIV: BM - Solid Matter Physics ; Magnetism; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Physical chemistry (UFCH-W) Impact factor: 13.942, year: 2016

  7. Comparison of slowness profiles of lamb wave with elastic moduli and crystal structure in single crystalline silicon wafers

    Energy Technology Data Exchange (ETDEWEB)

    Min, Young Jae; Yun, Gyeong Won; Kim, Kyung Min; Roh, Yuji; Kim, Young H. [Applied Acoustics Lab, Korea Science Academy of KAIST, Busan (Korea, Republic of)

    2016-02-15

    Single crystalline silicon wafers having (100), (110), and (111) directions are employed as specimens for obtaining slowness profiles. Leaky Lamb waves (LLW) from immersed wafers were detected by varying the incident angles of the specimens and rotating the specimens. From an analysis of LLW signals for different propagation directions and phase velocities of each specimen, slowness profiles were obtained, which showed a unique symmetry with different symmetric axes. Slowness profiles were compared with elastic moduli of each wafer. They showed the same symmetries as crystal structures. In addition, slowness profiles showed expected patterns and values that can be inferred from elastic moduli. This implies that slowness profiles can be used to examine crystal structures of anisotropic solids.

  8. Disposable attenuated total reflection-infrared crystals from silicon wafer: a versatile approach to surface infrared spectroscopy.

    Science.gov (United States)

    Karabudak, Engin; Kas, Recep; Ogieglo, Wojciech; Rafieian, Damon; Schlautmann, Stefan; Lammertink, R G H; Gardeniers, Han J G E; Mul, Guido

    2013-01-02

    Attenuated total reflection-infrared (ATR-IR) spectroscopy is increasingly used to characterize solids and liquids as well as (catalytic) chemical conversion. Here we demonstrate that a piece of silicon wafer cut by a dicing machine or cleaved manually can be used as disposable internal reflection element (IRE) without the need for polishing and laborious edge preparation. Technical aspects, fundamental differences, and pros and cons of these novel disposable IREs and commercial IREs are discussed. The use of a crystal (the Si wafer) in a disposable manner enables simultaneous preparation and analysis of substrates and application of ATR spectroscopy in high temperature processes that may lead to irreversible interaction between the crystal and the substrate. As representative application examples, the disposable IREs were used to study high temperature thermal decomposition and chemical changes of polyvinyl alcohol (PVA) in a titania (TiO(2)) matrix and assemblies of 65-450 nm thick polystyrene (PS) films.

  9. Study of a macrodefect in a silicon carbid single crystal by means of X-ray phase contrast

    Energy Technology Data Exchange (ETDEWEB)

    Argunova, T. S., E-mail: argunova2002@mail.ru [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Kohn, V. G. [National Research Centre “Kurchatov Institute” (Russian Federation); Lim, J. H. [Pohang Accelerator Laboratory (Korea, Republic of); Je, J. H. [Pohang University of Science and Technology, Department of Materials Science and Engineering (Korea, Republic of)

    2016-11-15

    The morphology of a macrodefect in a single-crystal silicon carbide wafer has been investigated by the computer simulation of an experimental X-ray phase-contrast image. A micropipe, i.e., a long cavity with a small (elliptical in the general case) cross section, in a single crystal has been considered as a macrodefect. A far-field image of micropipe has been measured with the aid of synchrotron radiation without a monochromator. The parameters of micropipe elliptical cross section are determined based on one projection in two directions: parallel and perpendicular to the X-ray beam propagation direction, when scanning along the pipe axis. The results demonstrate the efficiency of the phase contrast method supplemented with computer simulation for studying such macrodefects when the defect position in the sample volume is unknown beforehand.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-02-01

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

  11. Electrodeposition of cadmium on n-type silicon single crystals of ...

    African Journals Online (AJOL)

    sea

    type silicon have been studied as a function of different potential steps. Within appropriate potential ... including progressive nucleation on active sites and diffusion controlled cluster growth. ..... al CdSe nanocrystals on {111} gold. Surf. Sci.

  12. Extreme electronic bandgap modification in laser-crystallized silicon optical fibres

    Czech Academy of Sciences Publication Activity Database

    Healy, N.; Mailis, S.; Bulgakova, Nadezhda M.; Sazio, P.J.A.; Day, T.D.; Sparks, J.R.; Cheng, H.Y.; Badding, J.V.; Peacock, A.C.

    2014-01-01

    Roč. 13, č. 12 (2014), s. 1122-1127 ISSN 1476-1122 Institutional support: RVO:68378271 Keywords : strained silicon * modulation * generation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 36.503, year: 2014

  13. Performance of a monolithic LaBr{sub 3}:Ce crystal coupled to an array of silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ulyanov, Alexei, E-mail: alexey.uliyanov@ucd.ie [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Morris, Oran [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Department of Computer Science & Applied Physics, Galway-Mayo Institute of Technology, Galway (Ireland); Hanlon, Lorraine; McBreen, Sheila; Foley, Suzanne; Roberts, Oliver J.; Tobin, Isaac; Murphy, David; Wade, Colin [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Nelms, Nick; Shortt, Brian [European Space Agency, ESTEC, 2200 AG Noordwijk (Netherlands); Slavicek, Tomas; Granja, Carlos; Solar, Michael [Institute of Experimental and Applied Physics, Czech Technical University in Prague, 12800 Prague 2 (Czech Republic)

    2016-02-21

    A gamma-ray detector composed of a single 28×28×20 mm{sup 3} LaBr{sub 3}:Ce crystal coupled to a custom built 4×4 array of silicon photomultipliers was tested over an energy range of 30 keV to 9.3 MeV. The silicon photomultipliers were initially calibrated using 20 ns light pulses generated by a light emitting diode. The photodetector responses measured as a function of the number of incident photons were found to be non-linear and consistent with model predictions. Using corrections for the non-linearity of the silicon photomultipliers, the detector showed a linear response to gamma-rays with energies from 100 keV to the maximum available energy of 9.3 MeV. The energy resolution was found to be 4% FWHM at 662 keV. Despite the large thickness of the scintillator (20 mm) and a 5 mm thick optical window, the detector was capable of measuring the positions of the gamma-ray interaction points. The position resolution was measured at 356 keV and was found to be 8 mm FWHM in the detector plane and 11 mm FWHM for the depth of interaction. The detector can be used as a building block of a larger calorimeter system that is capable of measuring gamma-ray energies up to tens of MeV.

  14. Ray trace visualization of negative refraction of light in two-dimensional air-bridged silicon photonic crystal slabs at 1.55 microm.

    Science.gov (United States)

    Gan, Lin; Liu, Ya-Zhao; Li, Jiang-Yan; Zhang, Ze-Bo; Zhang, Dao-Zhong; Li, Zhi-Yuan

    2009-06-08

    We demonstrate design, fabrication, and ray trace observation of negative refraction of near-infrared light in a two-dimensional square lattice of air holes etched into an air-bridged silicon slab. Special surface morphologies are designed to reduce the impedance mismatch when light refracts from a homogeneous silicon slab into the photonic crystal slab. We clearly observed negative refraction of infrared light for TE-like modes in a broad wavelength range by using scanning near-field optical microscopy technology. The experimental results are in good agreement with finite-difference time-domain simulations. The results indicate the designed photonic crystal structure can serve as polarization beam splitter.

  15. The temperature gradient on section of casting in process of primary crystallization of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2008-08-01

    Full Text Available The methodology of defining in article was introduced the temperature gradient in process of primary crystallization during cooling the casting from chromium cast iron on basis of measurements of thermal field in test DTA-K3. Insert also the preliminary results of investigations of influence temperature gradient on structure of studied wear resistance chromium cast iron.

  16. Prevention and control of proliferative vitreoretinopathy: primary retinal detachment surgery using silicone oil as a planned two-stage procedure in high-risk cases.

    Science.gov (United States)

    Alexander, P; Prasad, R; Ang, A; Poulson, A V; Scott, J D; Snead, M P

    2008-06-01

    For rhegmatogenous retinal detachment, reattachment with a single procedure is associated with better visual outcomes. In the past, silicone oil has been used mostly as a last resort following failed primary surgery. This study evaluates a novel approach to patients at high risk of primary failure, using silicone tamponade as the primary stage of a planned two-stage procedure. We report a series of 140 eyes that underwent primary surgery for rhegmatogenous retinal detachment. Patients at higher risk of surgical failure (eg giant retinal tear, inability to posture, poor view, uncertainty of location of primary break, primary proliferative vitreoretinopathy (PVR), multiple tears with rolled posterior edges, retinoschisis/detachment, staphyloma with macular hole) were managed by a planned staged procedure using primary silicone oil tamponade. This was followed by silicone removal at a later date. Fifty-four eyes underwent scleral buckling alone, with primary success in 52/54 (96%). Fifty-three eyes underwent vitrectomy and gas, achieving primary success in 50/53 (94%). Thirty-three eyes were classified high risk and managed with primary silicone. Silicone was safely removed in 22/25. In eight eyes, silicone was retained without attempt at removal. In total, primary retinal reattachment was achieved in 128 of 140 eyes (91.4%). Of these, 124 (97%) did not require long-term tamponade. Only four eyes (2.9%) developed PVR. A planned two-stage approach to highrisk cases of retinal detachment using primary silicone oil tamponade followed by silicone removal can achieve a high primary reattachment rate with less than 3% incidence of PVR.

  17. Low-temperature crystallization of amorphous silicon and amorphous germanium by soft X-ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Heya, Akira, E-mail: heya@eng.u-hyogo.ac.jp [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Kanda, Kazuhiro [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Toko, Kaoru; Sadoh, Taizoh [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Amano, Sho [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Matsuo, Naoto [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Miyamoto, Shuji [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Mochizuki, Takayasu [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan)

    2013-05-01

    The low-temperature-crystallization effects of soft X-ray irradiation on the structural properties of amorphous Si and amorphous Ge films were investigated. From the differences in crystallization between Si and Ge, it was found that the effects of soft X-ray irradiation on the crystallization strongly depended on the energy band gap and energy level. The crystallization temperatures of the amorphous Si and amorphous Ge films decreased from 953 K to 853 K and 773 K to 663 K, respectively. The decrease in crystallization temperature was also related to atoms transitioning into a quasi-nucleic phase in the films. The ratio of electron excitation and migration effects to thermal effects was controlled using the storage-ring current (photon flux density). Therefore, we believe that low-temperature crystallization can be realized by controlling atomic migration through electron excitation. - Highlights: • This work investigates the crystallization mechanism for soft X-ray irradiation. • The soft X-ray crystallization depended on the energy band gap and energy level. • The decrease in the crystallization temperature for Si and Ge films was 100 K. • This decrement was related to atoms transitioning into a quasi-nucleic phase.

  18. Numerically simulated and experimentally obtained X-ray section topographs of a spherical strain field in a floating zone silicon crystal

    International Nuclear Information System (INIS)

    Okitsu, Kouhei; Iida, Satoshi; Sugita, Yoshimitsu; Takeno, Hiroshi; Yagou, Yasuyoshi; Kawata, Hiroshi.

    1992-01-01

    An undoped floating zone (FZ) silicon crystal has been investigated by synchrotron X-radiation section topography with high-order reflections up to 14 14 0. Numerically simulated topographs based on the Takagi-Taupin equations were in good agreement with experimental distorted patterns when a spherical strain field was assumed in the crystal. The volume change of the lattice caused by the strain center was estimated to correspond to a sphere with a radius of 10 μm. (author)

  19. Current status of three-dimensional silicon photonic crystals operating at infrared wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    LIN,SHAWN-YU; FLEMING,JAMES G.; SIGALAS,M.M.; BISWAS,R.; HO,K.M.

    2000-05-11

    In this paper, the experimental realization and promises of three-dimensional (3D) photonic crystals in the infrared and optical wavelengths will be described. Emphasis will be placed on the development of new 3D photonic crystals, the micro- and nano-fabrication techniques, the construction of high-Q micro-cavities and the creation of 3D waveguides.

  20. Summary of structural refinement in hi-silicon aluminium piston alloy with phosphorous as grain refiner

    International Nuclear Information System (INIS)

    Malik, F.A.; Sheikh, S.T.; Choudhry, A.A.

    2003-01-01

    Aluminium Silicon Alloys are extensively used in a wide variety of applications. There are numerous variables in composition, production control, final structure which can influence the mechanical properties of Hi - Silicon Piston alloys. Hypereutectic AlSi alloys develop coarse grain primary silicon crystals, which have a strong negative effect on the tensile strength, the ductility, and the hardness. These crystals slow machining and reduce the tool life considerably. Phosphorous addition produce a fine, evenly spread crystal structure, lamellar structure of the silicon changes into a granular structure. (author)

  1. Efficient Fluorescence Resonance Energy Transfer between Quantum Dots and Gold Nanoparticles Based on Porous Silicon Photonic Crystal for DNA Detection.

    Science.gov (United States)

    Zhang, Hongyan; Lv, Jie; Jia, Zhenhong

    2017-05-10

    A novel assembled biosensor was prepared for detecting 16S rRNA, a small-size persistent specific for Actinobacteria. The mechanism of the porous silicon (PS) photonic crystal biosensor is based on the fluorescence resonance energy transfer (FRET) between quantum dots (QDs) and gold nanoparticles (AuNPs) through DNA hybridization, where QDs act as an emission donor and AuNPs serve as a fluorescence quencher. Results showed that the photoluminescence (PL) intensity of PS photonic crystal was drastically increased when the QDs-conjugated probe DNA was adhered to the PS layer by surface modification using a standard cross-link chemistry method. The PL intensity of QDs was decreased when the addition of AuNPs-conjugated complementary 16S rRNA was dropped onto QDs-conjugated PS. Based on the analysis of different target DNA concentration, it was found that the decrease of the PL intensity showed a good linear relationship with complementary DNA concentration in a range from 0.25 to 10 μM, and the detection limit was 328.7 nM. Such an optical FRET biosensor functions on PS-based photonic crystal for DNA detection that differs from the traditional FRET, which is used only in liquid. This method will benefit the development of a new optical FRET label-free biosensor on Si substrate and has great potential in biochips based on integrated optical devices.

  2. Effect of Silicon Substitution on the Crystal Properties of Cyanate Ester Monomers (Briefing Charts)

    Science.gov (United States)

    2015-08-17

    unlimited.   Outline • Background / Motivation – Cyanate esters – Reasons for incorporating silicon into thermosetting resins • Cyanate esters with...Approved for public release; distribution is unlimited.   The Use of Si in Thermosetting Polymers • In addition to the expected increase in short

  3. Single-crystal-like GdNdO{sub x} thin films on silicon substrates by magnetron sputtering and high-temperature annealing for crystal seed layer application

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ziwei; Xiao, Lei; Liang, Renrong, E-mail: wang-j@tsinghua.edu.cn, E-mail: liangrr@tsinghua.edu.cn; Shen, Shanshan; Xu, Jun; Wang, Jing, E-mail: wang-j@tsinghua.edu.cn, E-mail: liangrr@tsinghua.edu.cn [Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2016-06-15

    Single-crystal-like rare earth oxide thin films on silicon (Si) substrates were fabricated by magnetron sputtering and high-temperature annealing processes. A 30-nm-thick high-quality GdNdO{sub x} (GNO) film was deposited using a high-temperature sputtering process at 500°C. A Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} mixture was used as the sputtering target, in which the proportions of Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} were controlled to make the GNO’s lattice parameter match that of the Si substrate. To further improve the quality of the GNO film, a post-deposition annealing process was performed at a temperature of 1000°C. The GNO films exhibited a strong preferred orientation on the Si substrate. In addition, an Al/GNO/Si capacitor was fabricated to evaluate the dielectric constant and leakage current of the GNO films. It was determined that the single-crystal-like GNO films on the Si substrates have potential for use as an insulator layer for semiconductor-on-insulator and semiconductor/insulator multilayer applications.

  4. Single-crystal-like GdNdOx thin films on silicon substrates by magnetron sputtering and high-temperature annealing for crystal seed layer application

    Directory of Open Access Journals (Sweden)

    Ziwei Wang

    2016-06-01

    Full Text Available Single-crystal-like rare earth oxide thin films on silicon (Si substrates were fabricated by magnetron sputtering and high-temperature annealing processes. A 30-nm-thick high-quality GdNdOx (GNO film was deposited using a high-temperature sputtering process at 500°C. A Gd2O3 and Nd2O3 mixture was used as the sputtering target, in which the proportions of Gd2O3 and Nd2O3 were controlled to make the GNO’s lattice parameter match that of the Si substrate. To further improve the quality of the GNO film, a post-deposition annealing process was performed at a temperature of 1000°C. The GNO films exhibited a strong preferred orientation on the Si substrate. In addition, an Al/GNO/Si capacitor was fabricated to evaluate the dielectric constant and leakage current of the GNO films. It was determined that the single-crystal-like GNO films on the Si substrates have potential for use as an insulator layer for semiconductor-on-insulator and semiconductor/insulator multilayer applications.

  5. In situ observation of ultrasonic cavitation-induced fragmentation of the primary crystals formed in Al alloys.

    Science.gov (United States)

    Wang, Feng; Tzanakis, Iakovos; Eskin, Dmitry; Mi, Jiawei; Connolley, Thomas

    2017-11-01

    The cavitation-induced fragmentation of primary crystals formed in Al alloys were investigated for the first time by high-speed imaging using a novel experimental approach. Three representative primary crystal types, Al 3 Ti, Si and Al 3 V with different morphologies and mechanical properties were first extracted by deep etching of the corresponding Al alloys and then subjected to ultrasonic cavitation processing in distilled water. The dynamic interaction between the cavitation bubbles and primary crystals was imaged in situ and in real time. Based on the recorded image sequences, the fragmentation mechanisms of primary crystals were studied. It was found that there are three major mechanisms by which the primary crystals were fragmented by cavitation bubbles. The first one was a slow process via fatigue-type failure. A cyclic pressure exerted by stationary pulsating bubbles caused the propagation of a crack pre-existing in the primary crystal to a critical length which led to fragmentation. The second mechanism was a sudden process due to the collapse of bubbles in a passing cavitation cloud. The pressure produced upon the collapse of the cloud promoted rapid monotonic crack growth and fast fracture in the primary crystals. The third observed mechanism was normal bending fracture as a result of the high pressure arising from the collapse of a bubble cloud and the crack formation at the branch connection points of dendritic primary crystals. The fragmentation of dendrite branches due to the interaction between two freely moving dendritic primary crystals was also observed. A simplified fracture analysis of the observed phenomena was performed. The specific fragmentation mechanism for the primary crystals depended on their morphology and mechanical properties. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  6. All-optically tunable waveform synthesis by a silicon nanowaveguide ring resonator coupled with a photonic-crystal fiber frequency shifter

    KAUST Repository

    Savvin, Aleksandr D.

    2011-03-01

    A silicon nanowaveguide ring resonator is combined with a photonic-crystal fiber (PCF) frequency shifter to demonstrate an all-optically tunable synthesis of ultrashort pulse trains, modulated by ultrafast photoinduced free-carrier generation in the silicon resonator. Pump-probe measurements performed with a 50-fs, 625-nm second-harmonic output of a Cr:forsterite laser, used as a carrier-injecting pump, and a 1.50-1.56-μm frequency-tunable 100-fs soliton output of a photonic-crystal fiber, serving as a probe, resolve tunable ultrafast oscillatory features in the silicon nanowaveguide resonator response. © 2010 Elsevier B.V. All rights reserved.

  7. All-optically tunable waveform synthesis by a silicon nanowaveguide ring resonator coupled with a photonic-crystal fiber frequency shifter

    KAUST Repository

    Savvin, Aleksandr D.; Melnikov, Vasily; Fedotov, Il'ya V.; Fedotov, Andrei B.; Perova, Tatiana S.; Zheltikov, Aleksei M.

    2011-01-01

    A silicon nanowaveguide ring resonator is combined with a photonic-crystal fiber (PCF) frequency shifter to demonstrate an all-optically tunable synthesis of ultrashort pulse trains, modulated by ultrafast photoinduced free-carrier generation in the silicon resonator. Pump-probe measurements performed with a 50-fs, 625-nm second-harmonic output of a Cr:forsterite laser, used as a carrier-injecting pump, and a 1.50-1.56-μm frequency-tunable 100-fs soliton output of a photonic-crystal fiber, serving as a probe, resolve tunable ultrafast oscillatory features in the silicon nanowaveguide resonator response. © 2010 Elsevier B.V. All rights reserved.

  8. Buried oxide layer in silicon

    Science.gov (United States)

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

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

  9. MICROSTRUCTURING OF SILICON SINGLE CRYSTALS BY FIBER LASER IN HIGH-SPEED SCANNING MODE

    Directory of Open Access Journals (Sweden)

    T. A. Trifonova

    2015-11-01

    Full Text Available Subject of Study. The surface structure of the silicon wafers (substrate with a thermally grown silicon dioxide on the surface (of SiO2/Si is studied after irradiation by pulse fiber laser of ILI-1-20 type. The main requirements for exposure modes of the system are: the preservation of the integrity of the film of silicon dioxide in the process of microstructuring and the absence of interference of surrounding irradiated areas of the substrate. Method. Studies were carried out on silicon wafers KEF-4,5 oriented in the crystallographic plane (111 with the source (natural silicon dioxide (SiO2 with thickness of about 4 nm, and SiO2 with 40 nm and 150 nm thickness, grown by thermal oxidation in moist oxygen. Also, wafers KHB-10 oriented in the plane (100 with 500 nm thickness of thermal oxide were investigated. Irradiation of SiO2/Si system was produced by laser complex based on ytterbium fiber pulse laser ILI-1-20. Nominal output power of the laser was 20 W, and the laser wavelength was λ = 1062 nm. Irradiation was carried out by a focused beam spot with a diameter of 25 microns and a pulse repetition rate of 99 kHz. The samples with 150 nm and 40 nm thickness of SiO2 were irradiated at a power density equal to 1,2·102 W/cm2, and the samples of SiO2 with 500 nm thickness were irradiated at a power density equal to 2,0·102 W/cm2. Scanning was performed using a two-axis Coordinate Scanning Device based on VM2500+ drives with control via a PC with the software package "SinMarkTM." Only one scan line was used at the maximum speed of the beam equal to 8750 mm/s. Morphology control of the irradiated samples was conducted by an optical microscope ZeissA1M with high-resolution CCD array. A scanning probe microscope Nanoedicator of the NT-MDT company was used for structural measurements. Main Results. It has been shown that at a single exposure of high-frequency pulsed laser radiation on SiO2/Si system, with maintaining the integrity of the SiO2 film

  10. Tensometrical properties of volumetric crystals of germanium-silicon solid solutions irradiated by fast electrons

    International Nuclear Information System (INIS)

    Abbasov, Sh.M.

    2002-01-01

    Full Text: In the present work the tensometrical properties of Ge1-xSix solid solution monocrystal contended of up to 15 at. % Si were investigated. The radiation-proof strain gauges of researched crystals were made. For this purpose the site was cutted out from a sample, perpendicularly or in parallel of a crystal axes. After polishing the samples had thickness of 30-40 microns, and length of 2 mm

  11. Radiation hardness test of un-doped CsI crystals and Silicon Photomultipliers for the Mu2e calorimeter

    Science.gov (United States)

    Baccaro, S.; Cemmi, A.; Cordelli, M.; Diociaiuti, E.; Donghia, R.; Giovannella, S.; Loreti, S.; Miscetti, S.; Pillon, M.; Sarra, I.

    2017-11-01

    The Mu2e calorimeter is composed by 1400 un-doped CsI crystals coupled to large area UV extended Silicon Photomultipliers arranged in two annular disks. This calorimeter has to provide precise information on energy, timing and position. It should also be fast enough to handle the high rate background and it must operate and survive in a high radiation environment. Simulation studies estimated that, in the hottest regions, each crystal will absorb a dose of 300 Gy and will be exposed to a neutron fluency of 6 × 1011 n/cm2 in 3 years of running. Test of un-doped CsI crystals irradiated up to 900 Gy and to a neutron fluency up to 9 × 1011 n/cm2 have been performed at CALLIOPE and FNG ENEA facilities in Italy. We present our study on the variation of light yield (LY) and longitudinal response uniformity (LRU) of these crystals after irradiation. The ionization dose does not modify LRU while a 20% reduction in LY is observed at 900 Gy. Similarly, the neutron flux causes an acceptable LY deterioration (≤ 15%). A neutron irradiation test on different types of SIPMs (two different array models from Hamamatsu and one from FBK) have also been carried out by measuring the variation of the leakage current and the charge response to an ultraviolet led. We concluded that, in the experiment, we will need to cool down the SIPMs to 0 °C reduce the leakage current to an acceptable level.

  12. Ultra-flattened nearly-zero dispersion and ultrahigh nonlinear slot silicon photonic crystal fibers with ultrahigh birefringence

    Science.gov (United States)

    Liao, Jianfei; Xie, Yingmao; Wang, Xinghua; Li, Dongbo; Huang, Tianye

    2017-07-01

    A slot silicon photonic crystal fiber (PCF) is proposed to simultaneously achieve ultrahigh birefringence, large nonlinearity and ultra-flattened nearly-zero dispersion over a wide wavelength range. By taking advantage on the slot effect, ultrahigh birefringence up to 0.0736 and ultrahigh nonlinear coefficient up to 211.48 W-1 m-1 for quasi-TE mode can be obtained at the wavelength of 1.55 μm. Moreover, ultra-flattened dispersion of 0.49 ps/(nm km) for quasi-TE mode can be achieved over a 180 nm wavelength range with low dispersion slope of 1.85 × 10-3 ps/(nm2 km) at 1.55 μm. Leveraging on these advantages, the proposed slot PCF has great potential for efficient all-optical signal processing applications.

  13. Investigation of phase matching for third-harmonic generation in silicon slow light photonic crystal waveguides using Fourier optics.

    Science.gov (United States)

    Monat, Christelle; Grillet, Christian; Corcoran, Bill; Moss, David J; Eggleton, Benjamin J; White, Thomas P; Krauss, Thomas F

    2010-03-29

    Using Fourier optics, we retrieve the wavevector dependence of the third-harmonic (green) light generated in a slow light silicon photonic crystal waveguide. We show that quasi-phase matching between the third-harmonic signal and the fundamental mode is provided in this geometry by coupling to the continuum of radiation modes above the light line. This process sustains third-harmonic generation with a relatively high efficiency and a substantial bandwidth limited only by the slow light window of the fundamental mode. The results give us insights into the physics of this nonlinear process in the presence of strong absorption and dispersion at visible wavelengths where bandstructure calculations are problematic. Since the characteristics (e.g. angular pattern) of the third-harmonic light primarily depend on the fundamental mode dispersion, they could be readily engineered.

  14. Efficient continuous-wave nonlinear frequency conversion in high-Q gallium nitride photonic crystal cavities on silicon

    Directory of Open Access Journals (Sweden)

    Mohamed Sabry Mohamed

    2017-03-01

    Full Text Available We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG and third harmonic generation (THG in suspended gallium nitride slab photonic crystal (PhC cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4 × 104, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving a normalized conversion efficiency of 2.4 × 10−3 W−1, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.

  15. Optical Effects Accompanying the Dynamical Bragg Diffraction in Linear 1D Photonic Crystals Based on Porous Silicon

    Directory of Open Access Journals (Sweden)

    Anton Maydykovskiy

    2014-10-01

    Full Text Available We survey our recent results on the observation and studies of the effects accompanying the dynamical Bragg diffraction in one-dimensional photonic crystals (PhC. Contrary to the kinematic Bragg diffraction, the dynamical one considers a continuous interaction between the waves travelling within a spatially-periodic structure and is the most pronounced in the so called Laue geometry, leading to a number of exciting phenomena. In the described experiments, we study the PhC based on porous silicon or porous quartz, made by the electrochemical etching of crystalline silicon with the consequent thermal annealing. Importantly, these PhC are approximately hundreds of microns thick and contain a few hundreds of periods, so that the experiments in the Laue diffraction scheme are available. We discuss the effect of the temporal splitting of femtosecond laser pulses and show that the effect is quite sensitive to the polarization and the phase of a femtosecond laser pulse. We also show the experimental realization of the Pendular effect in porous quartz PhC and demonstrate the experimental conditions for the total spatial switching of the output radiation between the transmitted and diffracted directions. All described effects are of high interest for the control over the light propagation based on PhC structures.

  16. Quasi-periodic Fibonacci and periodic one-dimensional hypersonic phononic crystals of porous silicon: Experiment and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Aliev, Gazi N., E-mail: g.aliev@bath.ac.uk; Goller, Bernhard [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom)

    2014-09-07

    A one-dimensional Fibonacci phononic crystal and a distributed Bragg reflector were constructed from porous silicon. The structures had the same number of layers and similar acoustic impedance mismatch, and were electrochemically etched in highly boron doped silicon wafers. The thickness of the individual layers in the stacks was approximately 2 μm. Both types of hypersonic band gap structure were studied by direct measurement of the transmittance of longitudinal acoustic waves in the 0.1–2.6 GHz range. Acoustic band gaps deeper than 50 dB were detected in both structures. The experimental results were compared with model calculations employing the transfer matrix method. The acoustic properties of periodic and quasi-periodic structures in which half-wave retarding bi-layers do not consist of two quarter-wave retarding layers are discussed. The strong correlation between width and depth of gaps in the transmission spectra is demonstrated. The dominant mechanisms of acoustic losses in porous multilayer structures are discussed. The elastic constants remain proportional over our range of porosity, and hence, the Grüneisen parameter is constant. This simplifies the expression for the porosity dependence of the Akhiezer damping.

  17. LSSA large area silicon sheet task continuous Czochralski process development

    Science.gov (United States)

    Rea, S. N.

    1978-01-01

    A Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a premelter to provide molten silicon flow into the primary crucible. The basic furnace is operational and several trial crystals were grown in the batch mode. Numerous premelter configurations were tested both in laboratory-scale equipment as well as in the actual furnace. The best arrangement tested to date is a vertical, cylindrical graphite heater containing small fused silicon test tube liner in which the incoming silicon is melted and flows into the primary crucible. Economic modeling of the continuous Czochralski process indicates that for 10 cm diameter crystal, 100 kg furnace runs of four or five crystals each are near-optimal. Costs tend to asymptote at the 100 kg level so little additional cost improvement occurs at larger runs. For these conditions, crystal cost in equivalent wafer area of around $20/sq m exclusive of polysilicon and slicing was obtained.

  18. Analysis of signals propagating in a phononic crystal PZT layer deposited on a silicon substrate.

    Science.gov (United States)

    Hladky-Hennion, Anne-Christine; Vasseur, Jérôme; Dubus, Bertrand; Morvan, Bruno; Wilkie-Chancellier, Nicolas; Martinez, Loïc

    2013-12-01

    The design of a stop-band filter constituted by a periodically patterned lead zirconate titanate (PZT) layer, polarized along its thickness, deposited on a silicon substrate and sandwiched between interdigitated electrodes for emission/reception of guided elastic waves, is investigated. The filter characteristics are theoretically evaluated by using finite element simulations: dispersion curves of a patterned PZT layer with a specific pattern geometry deposited on a silicon substrate present an absolute stop band. The whole structure is modeled with realistic conditions, including appropriate interdigitated electrodes to propagate a guided mode in the piezoelectric layer. A robust method for signal analysis based on the Gabor transform is applied to treat transmitted signals; extract attenuation, group delays, and wave number variations versus frequency; and identify stop-band filter characteristics.

  19. Increasing the radiation resistance of single-crystal silicon epitaxial layers

    Directory of Open Access Journals (Sweden)

    Kurmashev Sh. D.

    2014-12-01

    Full Text Available The authors investigate the possibility of increasing the radiation resistance of silicon epitaxial layers by creating radiation defects sinks in the form of dislocation networks of the density of 109—1012 m–2. Such networks are created before the epitaxial layer is applied on the front surface of the silicon substrate by its preliminary oxidation and subsequent etching of the oxide layer. The substrates were silicon wafers KEF-4.5 and KDB-10 with a diameter of about 40 mm, grown by the Czochralski method. Irradiation of the samples was carried out using electron linear accelerator "Electronics" (ЭЛУ-4. Energy of the particles was 2,3—3,0 MeV, radiation dose 1015—1020 m–2, electron beam current 2 mA/m2. It is shown that in structures containing dislocation networks, irradiation results in reduction of the reverse currents by 5—8 times and of the density of defects by 5—10 times, while the mobility of the charge carriers is increased by 1,2 times. Wafer yield for operation under radiation exposure, when the semiconductor structures are formed in the optimal mode, is increased by 7—10% compared to the structures without dislocation networks. The results obtained can be used in manufacturing technology for radiation-resistant integrated circuits (bipolar, CMOS, BiCMOS, etc..

  20. Energy loss distributions of 7 TeV protons channeled in a bent silicon crystals

    Directory of Open Access Journals (Sweden)

    Stojanov Nace

    2013-01-01

    Full Text Available The energy loss distributions of relativistic protons axially channeled through the bent Si crystals, with the constant curvature radius, R = 50 m, are studied here. The proton energy is 7 TeV and the thickness of the crystal is varied from 1 mm to 5 mm, which corresponds to the reduced crystal thickness, L, from 2.1 to 10.6, respectively. The proton energy was chosen in accordance with the large hadron collider project, at the European Organization for Nuclear Research, in Geneva, Switzerland. The energy loss distributions of the channeled protons were generated by the computer simulation method using the numerical solution of the proton equations of motion in the transverse plane. Dispersion of the proton scattering angle caused by its collisions with the crystal’s electrons was taken into account. [Projekat Ministarstva nauke Republike Srbije, br. III 45006

  1. Characterization of lattice damage in ion implanted silicon: a Monte Carlo simulation combined with double crystal X-ray diffraction

    International Nuclear Information System (INIS)

    Cembali, F.; Mazzone, A.M.; Servidori, M.; Gabilli, E.; Lotti, R.

    1985-01-01

    Double crystal X-ray diffractometry is applied to the characterization of damage in silicon samples, irradiated with 60 keV self-ions for doses ranging from 5 x 10 12 cm -2 to the threshold for amorphisation. The samples were also electron beam annealed in such a condition as to give rise to a temperature of 800 0 C. The in-depth strain and atomic disorder distributions, due to the implantation defects, were determined for the specimens before and after high temperature annealing. This was possible by application of the dynamical theory of X-ray diffraction from imperfect crystals and by taking into account the diffuse (thermal, Compton) scattering accompanying Bragg diffraction intensity measurements. Transmission electron microscopy observations, in conventional (planar) and cross-section mode, were also performed. The results of these analyses were compared with a complex simulation method, designed to account for the physical origin of the disorder. The method consists of a Monte Carlo simulation of the damage growth during implantation and of the defect annealing and clustering in a warm lattice. The evolution of disorder is examined either in the phase of spontaneous annealing subsequent to the implantation or during the externally induced annealing. Theory and experiments led to a close characterization of damage in terms of cluster size, type and concentration, both before and after annealing. (author)

  2. Na-Si binary phase diagram and solution growth of silicon crystals

    International Nuclear Information System (INIS)

    Morito, H.; Yamada, T.; Ikeda, T.; Yamane, H.

    2009-01-01

    In the present study, a Na-Si binary phase diagram was first presented from the results of differential thermal analysis and X-ray diffraction. Based on the phase diagram, we performed low-temperature formation of single crystals, film and porous bulk of Si by vaporizing Na from a Na-Si melt at 800 or 900 deg. C.

  3. Multi-GeV electron and positron channeling in bent silicon crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sushko, Gennady B., E-mail: sushko@fias.uni-frankfurt.de [Goethe-Universitat Frankfurt am Main, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); Korol, Andrei V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); St. Petersburg State Maritime University, Leninsky Ave. 101, 198262 St. Petersburg (Russian Federation); Solov’yov, Andrey V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); A.F. Ioffe Physical-Technical Institute, Politekhnicheskaya ul. 26, 194021 St. Petersburg (Russian Federation)

    2015-07-15

    The planar channeling of 3…20 GeV electrons and positrons in bent Si(1 1 1) crystal was simulated by means of the MBN EXPLORER software package. The results of the simulations are analyzed in terms of dechanneling length characterization, angular distribution of outgoing projectiles and radiation spectrum. The results of calculations are compared with the recent experimental data.

  4. Thermal tuning of a silicon photonic crystal cavity infilled with an elastomer

    NARCIS (Netherlands)

    Erdamar, A.K.; Van Leest, M.M.; Picken, S.J.; Caro, J.

    2011-01-01

    Thermal tuning of the transmission of an elastomer infilled photonic crystal cavity is studied. An elastomer has a thermal expansion-induced negative thermo-optic coefficient that leads to a strong decrease of the refractive index upon heating. This property makes elastomer highly suitable for

  5. The effect of primary recoil spectrum on radiation induced segregation in nickel-silicon alloys

    Science.gov (United States)

    Averback, R. S.; Rehn, L. E.; Wagner, W.; Ehrhart, P.

    1983-08-01

    Segregation of silicon to the surface of Ni-12.7 at% Si alloys during 2.0-MeV He and 3.25-MeV Kr irradiations was measured using Rutherford backscattering spectrometry. For equal calculated defect production rates the Kr irradiation was Ni-Si alloys is presented which qualitatively explains the segregation results. The model assumes that small interstitial-atom-clusters form in individual cascades and that these clusters become trapped at silicon solute atoms. The vacancy thereby becomes the more mobile defect. The model should also have relevance for the observation that void swelling in nickel is suppressed by the addition of silicon solute.

  6. Deep level centers in electron-irradiated silicon crystals doped with copper at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yarykin, Nikolai [Institute of Microelectronics Technology, RAS, Chernogolovka (Russian Federation); Weber, Joerg [Technische Universitaet Dresden (Germany)

    2017-07-15

    The effect of bombardment with energetic particles on the deep-level spectrum of copper-contaminated silicon wafers is studied by space charge spectroscopy methods. The p-type FZ-Si wafers were doped with copper in the temperature range of 645-750 C and then irradiated with the 10{sup 15} cm{sup -2} fluence of 5 MeV electrons at room temperature. Only the mobile Cu{sub i} species and the Cu{sub PL} centers are detected in significant concentrations in the non-irradiated Cu-doped wafers. The properties of the irradiated samples are found to qualitatively depend on the copper in-diffusion temperature T{sub diff}. For T{sub diff} > 700 C, the irradiation partially reduces the Cu{sub i} concentration and introduces additional Cu{sub PL} centers while no standard radiation defects are detected. If T{sub diff} was below ∝700 C, the irradiation totally removes the mobile Cu{sub i} species. Instead, the standard radiation defects and their complexes with copper appear in the deep-level spectrum. A model for the defects reaction scheme during the irradiation is derived and discussed. DLTS spectrum of the Cu-contaminated and then irradiated silicon qualitatively depends on the copper in-diffusion temperature. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  8. Investigation of quantum states of fast electrons under planar channeling in silicon crystals

    International Nuclear Information System (INIS)

    Gridnev, V.I.; Kaplin, V.V.; Khlabutin, V.G.; Rozum, E.I.; Vorobiev, S.A.

    1987-01-01

    The angular distributions of (1.87 to 5.7) MeV electrons channeled in 2 μm Si crystals along (100), (110), and (111) atomic planes are measured. The half-width of measured angular distributions is defined by a critical Lindhard angle. A relation is obtained connecting those energies of electrons at which their angular distributions are similar for various atomic planes. The effect of a 'critical energy' under planar channeling of electrons is found and investigated. (author)

  9. Slow light enhanced optical nonlinearity in a silicon photonic crystal coupled-resonator optical waveguide.

    Science.gov (United States)

    Matsuda, Nobuyuki; Kato, Takumi; Harada, Ken-Ichi; Takesue, Hiroki; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya

    2011-10-10

    We demonstrate highly enhanced optical nonlinearity in a coupled-resonator optical waveguide (CROW) in a four-wave mixing experiment. Using a CROW consisting of 200 coupled resonators based on width-modulated photonic crystal nanocavities in a line defect, we obtained an effective nonlinear constant exceeding 10,000 /W/m, thanks to slow light propagation combined with a strong spatial confinement of light achieved by the wavelength-sized cavities.

  10. Superacid Passivation of Crystalline Silicon Surfaces.

    Science.gov (United States)

    Bullock, James; Kiriya, Daisuke; Grant, Nicholas; Azcatl, Angelica; Hettick, Mark; Kho, Teng; Phang, Pheng; Sio, Hang C; Yan, Di; Macdonald, Daniel; Quevedo-Lopez, Manuel A; Wallace, Robert M; Cuevas, Andres; Javey, Ali

    2016-09-14

    The reduction of parasitic recombination processes commonly occurring within the silicon crystal and at its surfaces is of primary importance in crystalline silicon devices, particularly in photovoltaics. Here we explore a simple, room temperature treatment, involving a nonaqueous solution of the superacid bis(trifluoromethane)sulfonimide, to temporarily deactivate recombination centers at the surface. We show that this treatment leads to a significant enhancement in optoelectronic properties of the silicon wafer, attaining a level of surface passivation in line with state-of-the-art dielectric passivation films. Finally, we demonstrate its advantage as a bulk lifetime and process cleanliness monitor, establishing its compatibility with large area photoluminescence imaging in the process.

  11. Origin of dislocation luminescence centers and their reorganization in p-type silicon crystal subjected to plastic deformation and high temperature annealing.

    Science.gov (United States)

    Pavlyk, Bohdan; Kushlyk, Markiyan; Slobodzyan, Dmytro

    2017-12-01

    Changes of the defect structure of silicon p-type crystal surface layer under the influence of plastic deformation and high temperature annealing in oxygen atmosphere were investigated by deep-level capacitance-modulation spectroscopy (DLCMS) and IR spectroscopy of molecules and atom vibrational levels. Special role of dislocations in the surface layer of silicon during the formation of its energy spectrum and rebuilding the defective structure was established. It is shown that the concentration of linear defects (N ≥ 10 4  cm -2 ) enriches surface layer with electrically active complexes (dislocation-oxygen, dislocation-vacancy, and dislocation-interstitial atoms of silicon) which are an effective radiative recombination centers.

  12. Summary of theoretical and experimental investigation of grating type, silicon photovoltaic cells. [using p-n junctions on light receiving surface of base crystal

    Science.gov (United States)

    Chen, L. Y.; Loferski, J. J.

    1975-01-01

    Theoretical and experimental aspects are summarized for single crystal, silicon photovoltaic devices made by forming a grating pattern of p/n junctions on the light receiving surface of the base crystal. Based on the general semiconductor equations, a mathematical description is presented for the photovoltaic properties of such grating-like structures in a two dimensional form. The resulting second order elliptical equation is solved by computer modeling to give solutions for various, reasonable, initial values of bulk resistivity, excess carrier concentration, and surface recombination velocity. The validity of the computer model is established by comparison with p/n devices produced by alloying an aluminum grating pattern into the surface of n-type silicon wafers. Current voltage characteristics and spectral response curves are presented for cells of this type constructed on wafers of different resistivities and orientations.

  13. High-efficiency deflection of high energy protons due to channeling along the 〈110〉 axis of a bent silicon crystal

    Directory of Open Access Journals (Sweden)

    W. Scandale

    2016-09-01

    Full Text Available A deflection efficiency of about 61% was observed for 400 GeV/c protons due to channeling, most strongly along the 〈110〉 axis of a bent silicon crystal. It is comparable with the deflection efficiency in planar channeling and considerably larger than in the case of the 〈111〉 axis. The measured probability of inelastic nuclear interactions of protons in channeling along the 〈110〉 axis is only about 10% of its amorphous level whereas in channeling along the (110 planes it is about 25%. High efficiency deflection and small beam losses make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles.

  14. Optimization and applications of planar silicon-based photonic crystal devices

    DEFF Research Database (Denmark)

    Borel, Peter Ingo; Frandsen, Lars Hagedorn; Burgos Leon, Juan

    2005-01-01

    such as topology optimization. We have also investigated a new device concept for coarse wavelength division de-multiplexing based on planar photonic crystal waveguides. The filtering of the wavelength channels has been realized by shifting the cut-off frequency of the fundamental photonic band gap mode...... in consecutive sections of the waveguide. Preliminary investigations show that this concepts allows coarse de-multiplexing to take place, but that optimization is required in order to reduce cross talk between adjacent channels and to increase the overall transmission. In this work the design, fabrication...

  15. Improved purification, crystallization and primary structure of pyruvate:ferredoxin oxidoreductase from Halobacterium halobium.

    Science.gov (United States)

    Plaga, W; Lottspeich, F; Oesterhelt, D

    1992-04-01

    An improved purification procedure, including nickel chelate affinity chromatography, is reported which resulted in a crystallizable pyruvate:ferredoxin oxidoreductase preparation from Halobacterium halobium. Crystals of the enzyme were obtained using potassium citrate as the precipitant. The genes coding for pyruvate:ferredoxin oxidoreductase were cloned and their nucleotide sequences determined. The genes of both subunits were adjacent to one another on the halobacterial genome. The derived amino acid sequences were confirmed by partial primary structure analysis of the purified protein. The structural motif of thiamin-diphosphate-binding enzymes was unequivocally located in the deduced amino acid sequence of the small subunit.

  16. Structure and morphology of surface of silicon crystals to be applied for channeling at relativistic energies

    International Nuclear Information System (INIS)

    Vomiero, Alberto; Restello, Silvio; Scian, Carlo; Marchi, Enrico Boscolo; Mea, Gianantonio Della; Guidi, Vincenzo; Milan, Emiliano; Baricordi, Stefano; Martinelli, Giuliano; Carnera, Alberto; Sambo, Andrea

    2006-01-01

    Bent crystals can be successfully applied for extraction/collimation of relativistic particles. A crucial feature to obtain high extraction efficiencies is the treatment of the surfaces being encountered by the beam, since mechanical operations induce considerable lattice imperfections. In order to remove the superficial damaged layer a planar etching can be applied on the surface exposed to the beam. This work presents a systematic study of the morphology and the crystalline perfection of the surface of the samples that have been used in accelerators with high efficiency. Crystals with different surface treatments have been investigated. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied on the characterisation of surface morphology. Low energy backscattering channeling of 2-MeV α particles or protons was used as a probe for the crystalline structure. The presence of a superficial damaged layer in the samples just after mechanical treatment was unveiled, while, in contrast, chemical etching leaves a surface with high crystalline perfection that can be related to the record efficiency

  17. Design of a micromachined terahertz electromagnetic crystals (EMXT) channel-drop filter on silicon-substrate

    Science.gov (United States)

    Zhou, Kai; Liu, Yong; Si, Liming; Lv, Xin

    2013-08-01

    An integrated 0.5 THz electromagnetic crystals(EMXT) channel-drop filter based on PBG structure is presented in this paper. A channel-drop filter is a device in which a narrow bandwidth is redirected to another "drop" waveguide while other frequencies are unaffected. It's capable of extracting a certain frequency from a continuous spectrum in the bus channel and passing it to the test channel. It has potential applications in photonic integrated circuits, radio astronomy, THz spectroscopy, THz communication and remote sensing radar receiver. PBG structures(or photonic crystals) are periodic structures which possess band gaps, where the electromagnetic wave of certain ranges of frequencies cannot pass through and is reflected. The proposed channel-drop filter consists of input waveguide,output waveguide and PBG structure. The proposed filter is simulated using the finite element method and can be fabricated by micro-electromechanical systems (MEMS) technology,due to its low cost, high performance and high processing precision.The filter operation principle and fabrication process are discussed.The simulation results show its ability to filter the frequency of 496GHz with a linewidth of approximately 4GHz and transmission of 27.2 dB above background.The loss at resonant frequency is less than 1dB considering the thickness and roughness of gold layer required by the MEMS process.The channel drop efficiency is 84%.

  18. Optical nose based on porous silicon photonic crystal infiltrated with ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haijuan [Institute of Microanalytical System, Department of Chemistry, Zhejiang University, Hangzhou, 3100058 (China); Zhejiang Academy of Medical Sciences, Hangzhou, 310013 (China); Lin, Leimiao; Liu, Dong; Chen, Qiaofen [Institute of Microanalytical System, Department of Chemistry, Zhejiang University, Hangzhou, 3100058 (China); Wu, Jianmin, E-mail: wjm-st1@zju.edu.cn [Institute of Microanalytical System, Department of Chemistry, Zhejiang University, Hangzhou, 3100058 (China)

    2017-02-08

    A photonic-nose for the detection and discrimination of volatile organic compounds (VOCs) was constructed. Each sensing element on the photonic sensor array was formed by infiltrating a specific type of ionic liquid (IL) into the pore channel of a patterned porous silicon (PSi) chip. Upon exposure to VOC, the density of IL dramatically decreased due to the nano-confinement effect. As a result, the IL located in pore channel expanded its volume and protrude out of the pore channel, leading to the formation of microdroplets on the PSi surface. These VOC-stimulated microdroplets could scatter the light reflected from the PSi rugate filter, thereby producing an optical response to VOC. The intensity of the optical response produced by IL/PSi sensor mainly depends on the size and shape of microdroplets, which is related to the concentration of VOC and the physi-chemical propertied of ILs. For ethanol vapor, the optical response has linear relationship with its relative vapor pressure within 0–60%. The LOD of the IL/PSi sensor for ethanol detection is calculated to be 1.3 ppm. It takes around 30 s to reach a full optical response, while the time for recovery is less than 1 min. In addition, the sensor displayed good stability and reproducibility. Owing to the different molecular interaction between IL and VOC, the ILs/PSi sensor array can generate a unique cross-reactive “fingerprint” in response to a specific type of VOC analyte. With the assistance of image technologies and principle components analysis (PCA), rapid discrimination of VOC analyte could be achieved based on the pattern recognition of photonic sensor array. The technology established in this work allows monitoring in-door air pollution in a visualized way. - Highlights: • Ionic liquids confined in the pore channel of porous silicon (PSi) can form microdroplets on the PSi surface upon exposure to VOCs. • These VOC-stimulated microdroplets could scattered the light reflected from the PSi rugate

  19. Local structure of the silicon implanted in a graphite single crystal

    International Nuclear Information System (INIS)

    Baba, Yuji; Shimoyama, Iwao; Sekiguchi, Tetsuhiro

    2002-01-01

    Solid carbon forms two kinds of local structures, i.e., diamond-like and two-dimensional graphite structures. In contrast, silicon carbide tends to prefer only diamond structure that is composed of sp 3 bonds. In order to clarify weather or not two-dimensional graphitic Si x C layer exists, we investigate the local structures of Si x C layer produced by Si + -ion implantation into highly oriented pyrolytic graphite (HOPG) by means of near-edge X-ray absorption fine structure (NEXAFS). The energy of the resonance peak in the Si K-edge NEXAFS spectra for Si + -implanted HOPG is lower than those for any other Si-containing materials. The intensity of the resonance peak showed a strong polarization dependence. These results suggests that the final state orbitals around Si atoms have π*-like character and the direction of this orbital is perpendicular to the graphite plane. It is elucidated that the Si-C bonds produced by the Si + -ion implantation are nearly parallel to the graphite plane, and Si x C phase forms a two-dimensionally spread graphite-like layer with sp 2 bonds. (author)

  20. Full characterization of laser-accelerated ion beams using Faraday cup, silicon carbide, and single-crystal diamond detectors

    Science.gov (United States)

    Margarone, D.; Krása, J.; Giuffrida, L.; Picciotto, A.; Torrisi, L.; Nowak, T.; Musumeci, P.; Velyhan, A.; Prokůpek, J.; Láska, L.; Mocek, T.; Ullschmied, J.; Rus, B.

    2011-05-01

    Multi-MeV beams of light ions have been produced using the 300 picosecond, kJ-class iodine laser, operating at the Prague Asterix Laser System facility in Prague. Real-time ion diagnostics have been performed by the use of various time-of-flight (TOF) detectors: ion collectors (ICs) with and without absorber thin films, new prototypes of single-crystal diamond and silicon carbide detectors, and an electrostatic ion mass spectrometer (IEA). In order to suppress the long photopeak induced by soft X-rays and to avoid the overlap with the signal from ultrafast particles, the ICs have been shielded with Al foil filters. The application of large-bandgap semiconductor detectors (>3 eV) ensured cutting of the plasma-emitted visible and soft-UV radiation and enhancing the sensitivity to the very fast proton/ion beams. Employing the IEA spectrometer, various ion species and charge states in the expanding laser-plasma have been determined. Processing of the experimental data based on the TOF technique, including estimation of the plasma fast proton maximum and peak energy, ion beam currents and total charge, total number of fast protons, as well as deconvolution processes, ion stopping power, and ion/photon transmission calculations for the different metallic filters used, are reported.

  1. Anomalous decrease of resistance at 250 K in ultrathin Au-Nb film on single-crystal silicon

    International Nuclear Information System (INIS)

    Yamamoto, H.; Kawashima, T.; Tanaka, M.

    1986-01-01

    Ultrathin Au-Nb films as thin as 0.2 about 10 nm were deposited on clean surfaces of single-crystal silicon in order to investigate interfacial excitonic superconductivity. The samples were classified into two types, Nb-Au/Si and Au-Nb-Au/Si. In the latter case, the secondary Au film was deposited on the former sample cooled by liquid nitrogen. In the Nb-Au/ Si type of sample, a sheet resistance, R /SUB s/ at room temperature abruptly increased from 10 3 Ωsq -1 order to about 10 5 Ωsq -1 in several days a few months after the sample preparation. Then the sample showed an anomalous decrease of R /SUB s/ at about 250 K and an approximately null resistance at lower temperatures. This phenomenon was not so stable and was observed only for a few days. The Au-Nb-Au/Si type of sample showed low R /SUB s/ (10 2 about 10 3 Ωsq -1 ) at room temperature. A decrease and disappearance of R /SUB s/ were also observed at about 240 K in the sample with comparatively good reproducibility. These phenomena are discussed qualitatively, based on the excitonic superconductive model for an interface of metal/semiconductor by Allender, Bray, and Bardeen

  2. The fabrication and visible-near-infrared optical modulation of vanadium dioxide/silicon dioxide composite photonic crystal structure

    Science.gov (United States)

    Liang, Jiran; Li, Peng; Song, Xiaolong; Zhou, Liwei

    2017-12-01

    We demonstrated a visible and near-infrared light tunable photonic nanostructure, which is composed of vanadium dioxide (VO2) thin film and silicon dioxide (SiO2) ordered nanosphere arrays. The vanadium films were sputtered on two-dimensional (2D) SiO2 sphere arrays. VO2 thin films were prepared by rapid thermal annealing (RTA) method with different oxygen flow rates. The close-packed VO2 shell formed a continuous surface, the composition of VO2 films in the structure changed when the oxygen flow rates increased. The 2D VO2/SiO2 composite photonic crystal structure exhibited transmittance trough tunability and near-infrared (NIR) transmittance modulation. When the oxygen flow rate increased from 3 slpm to 4 slpm, the largest transmittance trough can be regulated from 904 to 929 nm at low temperature, the transmittance troughs also appear blue shift when the VO2 phase changes from insulator to metal. The composite nanostructure based on VO2 films showed visible transmittance tunability, which would provide insights into the glass color changing in smart windows.

  3. The fabrication and visible-near-infrared optical modulation of vanadium dioxide/silicon dioxide composite photonic crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jiran; Li, Peng; Song, Xiaolong; Zhou, Liwei [Tianjin University, School of Microelectronics, Tianjin (China)

    2017-12-15

    We demonstrated a visible and near-infrared light tunable photonic nanostructure, which is composed of vanadium dioxide (VO{sub 2}) thin film and silicon dioxide (SiO{sub 2}) ordered nanosphere arrays. The vanadium films were sputtered on two-dimensional (2D) SiO{sub 2} sphere arrays. VO{sub 2} thin films were prepared by rapid thermal annealing (RTA) method with different oxygen flow rates. The close-packed VO{sub 2} shell formed a continuous surface, the composition of VO{sub 2} films in the structure changed when the oxygen flow rates increased. The 2D VO{sub 2}/SiO{sub 2} composite photonic crystal structure exhibited transmittance trough tunability and near-infrared (NIR) transmittance modulation. When the oxygen flow rate increased from 3 slpm to 4 slpm, the largest transmittance trough can be regulated from 904 to 929 nm at low temperature, the transmittance troughs also appear blue shift when the VO{sub 2} phase changes from insulator to metal. The composite nanostructure based on VO{sub 2} films showed visible transmittance tunability, which would provide insights into the glass color changing in smart windows. (orig.)

  4. Real-time Monitoring of Sustained Drug Release using the Optical Properties of Porous Silicon Photonic Crystal Particles

    Science.gov (United States)

    Wu, E.C.; Andrew, J.S.; Cheng, L; Freeman, W.R.; Pearson, L; Sailor, M.J.

    2011-01-01

    A controlled and observable drug delivery system that enables long-term local drug administration is reported. Biodegradable and biocompatible drug-loaded porous Si microparticles were prepared from silicon wafers, resulting in a porous 1-dimensional photonic crystal (rugate filter) approx. 12 micrometers thick and 35 micrometers across. An organic linker, 1-undecylenic acid, was attached to the Si-H terminated inner surface of the particles by hydrosilylation and the anthracycline drug daunorubicin was bound to the carboxy terminus of the linker. Degradation of the porous Si matrix in vitro was found to release the drug in a linear and sustained fashion for 30 d. The bioactivity of the released daunorubicin was verified on retinal pigment epithelial (RPE) cells. The degradation/drug delivery process was monitored in situ by digital imaging or spectroscopic measurement of the photonic resonance reflected from the nanostructured particles, and a simple linear correlation between observed wavelength and drug release was observed. Changes in the optical reflectance spectrum were sufficiently large to be visible as a distinctive red to green color change. PMID:21122914

  5. Adaptive optics scanning laser ophthalmoscope using liquid crystal on silicon spatial light modulator: Performance study with involuntary eye movement

    Science.gov (United States)

    Huang, Hongxin; Toyoda, Haruyoshi; Inoue, Takashi

    2017-09-01

    The performance of an adaptive optics scanning laser ophthalmoscope (AO-SLO) using a liquid crystal on silicon spatial light modulator and Shack-Hartmann wavefront sensor was investigated. The system achieved high-resolution and high-contrast images of human retinas by dynamic compensation for the aberrations in the eyes. Retinal structures such as photoreceptor cells, blood vessels, and nerve fiber bundles, as well as blood flow, could be observed in vivo. We also investigated involuntary eye movements and ascertained microsaccades and drifts using both the retinal images and the aberrations recorded simultaneously. Furthermore, we measured the interframe displacement of retinal images and found that during eye drift, the displacement has a linear relationship with the residual low-order aberration. The estimated duration and cumulative displacement of the drift were within the ranges estimated by a video tracking technique. The AO-SLO would not only be used for the early detection of eye diseases, but would also offer a new approach for involuntary eye movement research.

  6. Effect of Primary Recrystallized Microstructure and Nitriding on Secondary Recrystallization in Grain Oriented Silicon Steel by Low Temperature Slab Reheating

    Directory of Open Access Journals (Sweden)

    LIU Gong-tao

    2018-01-01

    Full Text Available Different primary recrystallized grain sizes were obtained by controlling decarburization process in grain oriented silicon steel produced by low temperature slab reheating technique. The effect of primary grain size on secondary recrystallization and magnetic properties was studied. The appropriate nitrogen content after nitriding was explored in case of very large primary grain size, and the effect of {411}〈148〉 primary recrystallized texture on the abnormal growth behavior was discussed. The results show that an increase in average primary grain size from 10μm to 15μm leads to an increase of secondary recrystallization temperature and a sharper Goss texture with higher magnetic permeability, in the condition of a very large average primary grain size of 28μm, the suitable amount of nitrogen increases to about 6×10-4. The {411}〈148〉 oriented grains in primary recrystallized microstructure can easily grow into larger sizes due to their size advantage, and thus hinder the abnormal growth of secondary grains, moreover, the hindering effect is more pronounced in the abnormal growth of Brass-oriented grains due to their misorientation with low migration rate other than Goss grains.

  7. Full-scale experiments on solid-pellets feed continuous Czochralski growth of silicon crystals

    Science.gov (United States)

    Anselmo, A.; Koziol, J.; Prasad, V.

    1996-06-01

    Two long-term solid-pellets feed continuous Czochralski growth experiments were performed in an industrial Czochralski crystal puller as an extension to our previous work [7]. The goals of these experiments were to examine how polysilicon pellets would melt in a standard Cz system, to discover the thermal effects the pellets would have on the overall melt, and to find if pellet addition could be an effective melt replenishment technique. These experiments demonstrate that the quality of the melt for the CCz growth is based heavily on the surface temperature of the melt. A novel characterization method ("impact severity") is developed to characterize the quality of the CCz melt. Stable feed rate and melt conditions were achieved for three different pull rates. These experiments demonstrate that the process is technically feasible, and can be retrofitted to the existing industrial systems. Several critical issues that need to be addressed to develop a successful CCz process are also discussed.

  8. Simple down conversion nano-crystal coatings for enhancing Silicon-solar cells efficiency

    Directory of Open Access Journals (Sweden)

    Gur Mittelman

    2016-09-01

    Full Text Available Utilizing self-assembled nano-structured coatings on top of existing solar cells has thepotential to increase the total quantum efficiency of the cell using a simple and cheap process. In ourwork we have exploited the controlled absorption of nano-crystal with different band gaps to realizedown conversion artificial antennas that self-assembled on the device surface. The UV sun light isconverted to the visible light enhancing the solar cell performance in two complementary routes; a.protecting the solar cell and coatings from the UV illumination and therefore reducing the UVradiation damage. b. enhancing the total external quantum efficiency of the cell by one percent. Thisis achieved using a simple cheap process that can be adjusted to many different solar cells.

  9. Effect of grain-boundary crystallization on the high-temperature strength of silicon nitride

    Science.gov (United States)

    Pierce, L. A.; Mieskowski, D. M.; Sanders, W. A.

    1986-01-01

    Si3N4 specimens having the composition 88.7 wt pct Si3N4-4.9 wt pct SiO2-6.4 wt pct Y2O3 were sintered at 2140 C under 25 atm N2 for 1 h and then subjected to a 5 h anneal at 1500 C. Crystallization of an amorphous grain-boundary phase resulted in the formation of Y2Si2O7. The short-time 1370 C strength of this material was compared with that of material of the same composition having no annealing treatment. No change in strength was noted. This is attributed to the refractory nature of the yttrium-rich grain-boundary phase (apparently identical in both glassy and crystalline phases) and the subsequent domination of the failure process by common processing flaws.

  10. Planar nucleation and crystallization in the annealing process of ion implanted silicon

    International Nuclear Information System (INIS)

    Luo Yimin; Chen Zhenhua; Chen Ding

    2010-01-01

    According to thermodynamic and kinetic theory, considering the variation of bulk free energy and superficial energy after nucleation as well as the migration of atoms, we study systematically the planar nucleation and crystallization that relate to two possible transition mechanisms in the annealing process of ion implanted Si: (1) liquid/solid transition: the critical nucleation work is equal to half the increased superficial energy and inversely proportional to the supercooling ΔT. Compared with bulk nucleation, the radius of the critical nucleus decreases by half, and the nucleation rate attains its maximum at T = T m /2. (2) amorphous/crystalline transition: the atoms contained in the critical nucleus and situated on its surface, as well as critical nucleation work, are all directly proportional to the height of the nucleus, and the nucleation barrier is equal to half the superficial energy too. In addition, we take SiGe semiconductor as a specific example for calculation; a value of 0.03 eV/atom is obtained for the elastic strain energy, and a more reasonable result can be gotten after taking into account its effect on transition Finally, we reach the following conclusion as a result of the calculation: for the annealing of ion implanted Si, no matter what the transition method is-liquid or solid planar nucleation-the recrystallization process is actually carried out layer by layer on the crystal substrate, and the probability of forming a 'rod-like' nucleus is much larger than that of a 'plate-like' nucleus. (semiconductor materials)

  11. Rotation of X-ray polarization in the glitches of a silicon crystal monochromator.

    Science.gov (United States)

    Sutter, John P; Boada, Roberto; Bowron, Daniel T; Stepanov, Sergey A; Díaz-Moreno, Sofía

    2016-08-01

    EXAFS studies on dilute samples are usually carried out by collecting the fluorescence yield using a large-area multi-element detector. This method is susceptible to the 'glitches' produced by all single-crystal monochromators. Glitches are sharp dips or spikes in the diffracted intensity at specific crystal orientations. If incorrectly compensated, they degrade the spectroscopic data. Normalization of the fluorescence signal by the incident flux alone is sometimes insufficient to compensate for the glitches. Measurements performed at the state-of-the-art wiggler beamline I20-scanning at Diamond Light Source have shown that the glitches alter the spatial distribution of the sample's quasi-elastic X-ray scattering. Because glitches result from additional Bragg reflections, multiple-beam dynamical diffraction theory is necessary to understand their effects. Here, the glitches of the Si(111) four-bounce monochromator of I20-scanning just above the Ni  K edge are associated with their Bragg reflections. A fitting procedure that treats coherent and Compton scattering is developed and applied to a sample of an extremely dilute (100 micromolal) aqueous solution of Ni(NO 3 ) 2 . The depolarization of the wiggler X-ray beam out of the electron orbit is modeled. The fits achieve good agreement with the sample's quasi-elastic scattering with just a few parameters. The X-ray polarization is rotated up to ±4.3° within the glitches, as predicted by dynamical diffraction. These results will help users normalize EXAFS data at glitches.

  12. Rotation of X-ray polarization in the glitches of a silicon crystal monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Sutter, John P.; Boada, Roberto; Bowron, Daniel T.; Stepanov, Sergey A.; Díaz-Moreno, Sofía

    2016-07-06

    EXAFS studies on dilute samples are usually carried out by collecting the fluorescence yield using a large-area multi-element detector. This method is susceptible to the `glitches' produced by all single-crystal monochromators. Glitches are sharp dips or spikes in the diffracted intensity at specific crystal orientations. If incorrectly compensated, they degrade the spectroscopic data. Normalization of the fluorescence signal by the incident flux alone is sometimes insufficient to compensate for the glitches. Measurements performed at the state-of-the-art wiggler beamline I20-scanning at Diamond Light Source have shown that the glitches alter the spatial distribution of the sample's quasi-elastic X-ray scattering. Because glitches result from additional Bragg reflections, multiple-beam dynamical diffraction theory is necessary to understand their effects. Here, the glitches of the Si(111) four-bounce monochromator of I20-scanning just above the Ni Kedge are associated with their Bragg reflections. A fitting procedure that treats coherent and Compton scattering is developed and applied to a sample of an extremely dilute (100 micromolal) aqueous solution of Ni(NO3)2. The depolarization of the wiggler X-ray beam out of the electron orbit is modeled. The fits achieve good agreement with the sample's quasi-elastic scattering with just a few parameters. The X-ray polarization is rotated up to ±4.3° within the glitches, as predicted by dynamical diffraction. These results will help users normalize EXAFS data at glitches.

  13. Modelling of heating and photoexcitation of single-crystal silicon under multipulse irradiation by a nanosecond laser at 1.06 μm

    Science.gov (United States)

    Polyakov, D. S.; Yakovlev, E. B.

    2018-03-01

    We report a theoretical study of heating and photoexcitation of single-crystal silicon by nanosecond laser radiation at a wavelength of 1.06 μm. The proposed physicomathematical model of heating takes into account the complex nonlinear dynamics of the interband absorption coefficient of silicon and the contribution of the radial heat removal to the cooling of silicon between pulses under multipulse irradiation, which allows one to obtain a satisfactory agreement between theoretical predictions of silicon melting thresholds at different nanosecond pulse durations and experimental data (both under single-pulse and multipulse irradiation). It is found that under irradiation by nanosecond pulses at a wavelength of 1.06 μm, the dynamic Burshtein–Moss effect can play an important role in processes of photoexcitation and heating. It is shown that with the regimes typical for laser multipulse microprocessing of silicon (the laser spot diameter is less than 100 μm, and the repetition rate of pulses is about 100 kHz), the radial heat removal cannot be neglected in the analysis of heat accumulation processes.

  14. Optical nose based on porous silicon photonic crystal infiltrated with ionic liquids.

    Science.gov (United States)

    Zhang, Haijuan; Lin, Leimiao; Liu, Dong; Chen, Qiaofen; Wu, Jianmin

    2017-02-08

    A photonic-nose for the detection and discrimination of volatile organic compounds (VOCs) was constructed. Each sensing element on the photonic sensor array was formed by infiltrating a specific type of ionic liquid (IL) into the pore channel of a patterned porous silicon (PSi) chip. Upon exposure to VOC, the density of IL dramatically decreased due to the nano-confinement effect. As a result, the IL located in pore channel expanded its volume and protrude out of the pore channel, leading to the formation of microdroplets on the PSi surface. These VOC-stimulated microdroplets could scatter the light reflected from the PSi rugate filter, thereby producing an optical response to VOC. The intensity of the optical response produced by IL/PSi sensor mainly depends on the size and shape of microdroplets, which is related to the concentration of VOC and the physi-chemical propertied of ILs. For ethanol vapor, the optical response has linear relationship with its relative vapor pressure within 0-60%. The LOD of the IL/PSi sensor for ethanol detection is calculated to be 1.3 ppm. It takes around 30 s to reach a full optical response, while the time for recovery is less than 1 min. In addition, the sensor displayed good stability and reproducibility. Owing to the different molecular interaction between IL and VOC, the ILs/PSi sensor array can generate a unique cross-reactive "fingerprint" in response to a specific type of VOC analyte. With the assistance of image technologies and principle components analysis (PCA), rapid discrimination of VOC analyte could be achieved based on the pattern recognition of photonic sensor array. The technology established in this work allows monitoring in-door air pollution in a visualized way. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Applications of Silicon-on-Insulator Photonic Crystal Structures in Miniature Spectrometer Designs

    Science.gov (United States)

    Gao, Boshen

    Optical spectroscopy is one of the most important fundamental scientific techniques. It has been widely adopted in physics, chemistry, biology, medicine and many other research fields. However, the size and weight of a spectrometer as well as the difficulty to align and maintain it have long limited spectroscopy to be a laboratory-only procedure. With the recent advancement in semiconductor electronics and photonics, miniaturized spectrometers have been introduced to complete many tasks in daily life where mobility and portability are necessary. This thesis focuses on the study of several photonic crystal (PC) nano-structures potentially suitable for miniaturized on-chip spectrometer designs. Chapter 1 briefly introduces the concept of PCs and their band structures. By analyzing the band structure, the origin of the superprism effect is explained. Defect-based PC nano-cavities are also discussed, as well as a type of coupled cavity waveguides (CCW) composed of PC nano-cavities. Chapter 2 is devoted to the optimization of a flat-band superprism structure for spectroscopy application using numerical simulations. Chapter 3 reports a fabricated broad-band superprism and the experimental characterization of its wavelength resolving performance. In chapter 4, the idea of composing a miniature spectrometer based on a single tunable PC nano-cavity is proposed. The rest of this chapter discusses the experimental study of this design. Chapter 5 examines the slow-light performance of a CCW and discusses its potential application in slow-light interferometry. Chapter 6 serves as a conclusion of this thesis and proposes directions for possible future work to follow up.

  16. LSA Large Area Silicon Sheet Task Continuous Czochralski Process Development

    Science.gov (United States)

    Rea, S. N.

    1979-01-01

    A commercial Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a small, in-situ premelter with attendant silicon storage and transport mechanisms. Using a vertical, cylindrical graphite heater containing a small fused quartz test tube linear from which the molten silicon flowed out the bottom, approximately 83 cm of nominal 5 cm diamter crystal was grown with continuous melt addition furnished by the test tube premelter. High perfection crystal was not obtained, however, due primarily to particulate contamination of the melt. A major contributor to the particulate problem was severe silicon oxide buildup on the premelter which would ultimately drop into the primary melt. Elimination of this oxide buildup will require extensive study and experimentation and the ultimate success of continuous Czochralski depends on a successful solution to this problem. Economically, the continuous Czochralski meets near-term cost goals for silicon sheet material.

  17. Stabilization of primary mobile radiation defects in MgF{sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lisitsyn, V.M. [National Research Tomsk Polytechnic University, pr. Lenina 30, Tomsk 634050 (Russian Federation); Lisitsyna, L.A. [State University of Architecture and Building, pl. Solyanaya 2, Tomsk 634003 (Russian Federation); Popov, A.I., E-mail: popov@ill.fr [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., LV-1063 Riga (Latvia); Kotomin, E.A. [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., LV-1063 Riga (Latvia); Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Abuova, F.U.; Akilbekov, A. [L.N. Gumilyov Eurasian National University, 3 Munaitpasova Str., Astana (Kazakhstan); Maier, J. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany)

    2016-05-01

    Non-radiative decay of the electronic excitations (excitons) into point defects (F–H pairs of Frenkel defects) is main radiation damage mechanism in many ionic (halide) solids. Typical time scale of the relaxation of the electronic excitation into a primary, short-lived defect pair is about 1–50 ps with the quantum yield up to 0.2–0.8. However, only a small fraction of these primary defects are spatially separated and survive after transformation into stable, long-lived defects. The survival probability (or stable defect accumulation efficiency) can differ by orders of magnitude, dependent on the material type; e.g. ∼10% in alkali halides with f.c.c. or b.c.c. structure, 0.1% in rutile MgF{sub 2} and <0.001% in fluorides MeF{sub 2} (Me: Ca, Sr, Ba). The key factor determining accumulation of stable radiation defects is stabilization of primary defects, first of all, highly mobile hole H centers, through their transformation into more complex immobile defects. In this talk, we present the results of theoretical calculations of the migration energies of the F and H centers in poorely studied MgF{sub 2} crystals with a focus on the H center stabilization in the form of the interstitial F{sub 2} molecules which is supported by presented experimental data.

  18. Role of fluttering dislocations in the thermal interface resistance between a silicon crystal and plastic solid 4He

    Science.gov (United States)

    Amrit, Jay; Ramiere, Aymeric; Volz, Sebastian

    2018-01-01

    A quantum solid (solid 4He) in contact with a classical solid defines a new class of interfaces. In addition to its quantum nature, solid 4He is indeed a very plastic medium. We examine the thermal interface resistance upon solidification of superfluid 4He in contact with a silicon crystal surface (111) and show that dislocations play a crucial role in the thermal interface transport. The growth of solid 4He and the measurements are conducted at the minimum of the melting curve of helium (0.778 K and ˜25 bar ). The results display a first-order transition in the Kapitza resistance from a value of RK ,L=(80 ±8 ) c m2K /W at a pressure of 24.5 bar to a value of RK ,S=(41.7 ±8 ) c m2K /W after the formation of solid helium at ˜25.2 bar . The drop in RK ,S is only of a factor of ˜2 , although transverse phonon modes in solid 4He now participate in heat transmission at the interface. We provide an explanation for the measured RK ,S by considering the interaction of thermal phonons with vibrating dislocations in solid 4He. We demonstrate that this mechanism, also called fluttering, induces a thermal resistance RF l∝NdT-6 , where T is the temperature and Nd is the density of dislocations. We estimate that for dislocation densities on the order of ˜107c m-2 , RF l predominates over the boundary resistance RK ,S. These fundamental findings shed light on the role of dislocations and provide a quantitative explanation for previous experiments which showed no measurable change in the Kapitza resistance between Cu and superfluid 4He upon solidification of the latter. This demonstrates the possibility of using dislocations as an additional means to tailor thermal resistances at interfaces, formed especially with a plastic material.

  19. Mass Spectrometric Investigation of Silicon Extremely Enriched in (28)Si: From (28)SiF4 (Gas Phase IRMS) to (28)Si Crystals (MC-ICP-MS).

    Science.gov (United States)

    Pramann, Axel; Rienitz, Olaf

    2016-06-07

    A new generation of silicon crystals even further enriched in (28)Si (x((28)Si) > 0.999 98 mol/mol), recently produced by companies and institutes in Russia within the framework of a project initiated by PTB, were investigated with respect to their isotopic composition and molar mass M(Si). A modified isotope dilution mass spectrometric (IDMS) method treating the silicon as the matrix containing a so-called virtual element (VE) existing of the isotopes (29)Si and (30)Si solely and high resolution multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) were applied in combination. This method succeeds also when examining the new materials holding merely trace amounts of (29)Si (x((29)Si) ≈ 5 × 10(-6) mol/mol) and (30)Si (x((30)Si) ≈ 7 × 10(-7) mol/mol) extremely difficult to detect with lowest uncertainty. However, there is a need for validating the enrichment in (28)Si already in the precursor material of the final crystals, silicon tetrafluoride (SiF4) gas prior to crystal production. For that purpose, the isotopic composition of selected SiF4 samples was determined using a multicollector magnetic sector field gas-phase isotope ratio mass spectrometer. Contaminations of SiF4 by natural silicon due to storing and during the isotope ratio mass spectrometry (IRMS) measurements were observed and quantified. The respective MC-ICP-MS measurements of the corresponding crystal samples show-in contrast-several advantages compared to gas phase IRMS. M(Si) of the new crystals were determined to some extent with uncertainties urel(M) < 1 × 10(-9). This study presents a clear dependence of the uncertainty urel(M(Si)) on the degree of enrichment in (28)Si. This leads to a reduction of urel(M(Si)) during the past decade by almost 3 orders of magnitude and thus further reduces the uncertainty of the Avogadro constant NA which is one of the preconditions for the redefinition of the SI unit kilogram.

  20. crystal

    Science.gov (United States)

    Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Sun, Shijia; Wang, Guofu

    2014-07-01

    A Nd3+:Na2La4(WO4)7 crystal with dimensions of ϕ 17 × 30 mm3 was grown by the Czochralski method. The thermal expansion coefficients of Nd3+:Na2La4(WO4)7 crystal are 1.32 × 10-5 K-1 along c-axis and 1.23 × 10-5 K-1 along a-axis, respectively. The spectroscopic characteristics of Nd3+:Na2La4(WO4)7 crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The absorption cross sections at 805 nm are 2.17 × 10-20 cm2 with a full width at half maximum (FWHM) of 15 nm for π-polarization, and 2.29 × 10-20 cm2 with a FWHM of 14 nm for σ-polarization. The emission cross sections are 3.19 × 10-20 cm2 for σ-polarization and 2.67 × 10-20 cm2 for π-polarization at 1,064 nm. The fluorescence quantum efficiency is 67 %. The quasi-cw laser of Nd3+:Na2La4(WO4)7 crystal was performed. The maximum output power is 80 mW. The slope efficiency is 7.12 %. The results suggest Nd3+:Na2La4(WO4)7 crystal as a promising laser crystal fit for laser diode pumping.

  1. FY 1977 Annual report on Sunshine Project results. Research and development of photovoltaic power generation systems (Research and development of particle nonacceleration growth type silicon thin-film crystals); 1977 nendo taiyoko hatsuden system no kenkyu kaihatsu seika hokokusho. Ryushi hikasoku seichogata silicon usumaku kessho no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1978-03-01

    As part of the research and development project for producing photovoltaic power generation systems at reduced cost, the R and D efforts are made for producing particle nonacceleration growth type silicon thin-film crystals. The research items are (1) research on thin-film crystals, and (2) research on cell-structuring method. The item (1) studies quantities, types and electrical properties of impurities and crystal defects in the polycrystalline ingots, produced by the Czochralski method from metal grade silicon and purified metal grade silicon stocks. Next, the substrate prepared above is coated with a thin film of silicon by the vapor-phase growth method with dichlorosilane as the source, to evaluate the thin-film crystals by measuring the crystal defects and lifetime of small numbers of carriers. The item (2) studies the effects of the solder dipping method. In addition, unevenness of photoelectric current is analyzed by a laser scanning microscope, to investigate the effects of the secondary impurities and crystal defects in the substrate crystals on photoelectric current. As a result, it is found that conversion efficiency is improved by grading the hole concentration in the p-type activated layer. The targets of 10 to 20 m{sup 2} as the area and 7 to 8% as the conversion efficiency are attained by preparing the crystals again. (NEDO)

  2. Advanced dendritic web growth development and development of single-crystal silicon dendritic ribbon and high-efficiency solar cell program

    Science.gov (United States)

    Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.; Hopkins, R. H.

    1986-01-01

    Efforts to demonstrate that the dendritic web technology is ready for commercial use by the end of 1986 continues. A commercial readiness goal involves improvements to crystal growth furnace throughput to demonstrate an area growth rate of greater than 15 sq cm/min while simultaneously growing 10 meters or more of ribbon under conditions of continuous melt replenishment. Continuous means that the silicon melt is being replenished at the same rate that it is being consumed by ribbon growth so that the melt level remains constant. Efforts continue on computer thermal modeling required to define high speed, low stress, continuous growth configurations; the study of convective effects in the molten silicon and growth furnace cover gas; on furnace component modifications; on web quality assessments; and on experimental growth activities.

  3. Primary processes and ionic reactions in the chemistry of recoiling silicon atoms

    International Nuclear Information System (INIS)

    Gaspar, P.P.; Garmestani, K.; Boo, B.H.; Stewart, G.W.

    1993-01-01

    Hot atom chemistry has permitted the elucidation of the chemistry of free atoms, and these include the polyvalent atoms of refractory group 14 elements, that is, carbon, silicon and germanium. Since no more than two bonds are formed normally in a single reactive collision of free atoms, the study on the chemistry of atoms like C, Si and Ge that require the formation of more than two bonds to saturate their chemical valence necessarily involves the study of reactive intermediates. By the studies on the chemistry of recoiling 31 Si atoms, the mechanistic conclusions reached are reported. The most important unanswered questions concerning the reaction of recoiling 31 Si atoms in the systems are shown, and progress has been made toward the answering. By using tetramethyl silane as a trapping agent for silicon ions, it has been established that the reaction of 31 Si ions contributes significantly to the formation of products in recoil systems. The studies by various researchers on this theme are reported. (K.I.)

  4. Numerical simulation of the oxygen concentration distribution in silicon melt for different crystal lengths during Czochralski growth with a transverse magnetic field

    Science.gov (United States)

    Chen, Jyh-Chen; Chiang, Pei-Yi; Nguyen, Thi Hoai Thu; Hu, Chieh; Chen, Chun-Hung; Liu, Chien-Cheng

    2016-10-01

    A three-dimensional simulation model is used to study the oxygen concentration distribution in silicon crystal during the Czochralski growth process under a transverse uniform magnetic field. The flow, temperature, and oxygen concentration distributions inside the furnace are calculated for different crystal lengths. There is significant variation in the flow structure in the melt with the growth length. The results show that in the initial stages, there is a decrease in the oxygen concentration at the crystal-melt interface as the length of the growing crystal increases. As the crystal lengthens further, a minimum value is reached after which the oxygen concentration increases continuously. This trend is consistent with that shown in the experimental results. The variation of the oxygen concentration with the growth length is strongly related to the depth of the melt in the crucible and the flow structure inside the melt. Better uniformity of the axial oxygen concentration can be achieved by proper adjustment of the crucible rotation rate during the growth process.

  5. Fabrication and optical characteristics of silicon-based two-dimensional wavelength division multiplexing splitter with photonic crystal directional waveguide couplers

    International Nuclear Information System (INIS)

    Liu, Cheng-Yang

    2011-01-01

    Photonic crystals have many potential applications because of their ability to control lightwave propagation. We report on the fabrication and optical properties of quasi-two-dimensional photonic crystals with triangular lattice of dielectric rods in air. Rod-type photonic crystal structures were fabricated in silicon by electron beam lithography and dry-etching techniques. Wavelength division multiplexing splitters were fabricated from two-dimensional photonic crystal directional waveguide couplers. Transmission spectra were measured and device operation was shown to be in agreement with theoretical calculations. The splitters can be used in visible light region. Such an approach to photonic element systems should enable new applications for designing components in photonic integrated circuits. -- Highlights: → We report the fabrication and optical properties of rod-type photonic crystal. → The splitter was fabricated by electron beam lithography and dry-etching techniques. → The splitter was composed of directional waveguide couplers. → Measured transmission spectra are in agreement with theoretical calculations. → The splitters can be used in visible light region.

  6. Surface (glyco-)proteins: primary structure and crystallization under microgravity conditions

    Science.gov (United States)

    Claus, H.; Akca, E.; Schultz, N.; Karbach, G.; Schlott, B.; Debaerdemaeker, T.; De Clercq, J.-P.; König, H.

    2001-08-01

    The Archaea comprise microorganisms that live under environmental extremes, like high temperature, low pH value or high salt concentration. Their cells are often covered by a single layer of (glyco)protein subunits (S-layer) in hexagonal arrangement. In order to get further hints about the molecular mechanisms of protein stabilization we compared the primary and secondary structures of archaeal S-layer (glyco)proteins. We found an increase of charged amino acids in the S-layer proteins of the extreme thermophilic species compared to their mesophilic counterparts. Our data and those of other authors suggest that ionic interactions, e.g., salt bridges seem to be played a major role in protein stabilization at high temperatures. Despite the differences in the growth optima and the predominance of some amino acids the primary structures of S-layers revealed also a significant degree of identity between phylogenetically related archaea. These obervations indicate that protein sequences of S-layers have been conserved during the evolution from extremely thermophilic to mesophilic life. To support these findings the three-dimensional structure of the S-layer proteins has to be elucidated. Recently, we described the first successful crystallization of an extreme thermophilic surface(glyco)protein under microgravity conditions.

  7. Primary and aggregate color centers in proton irradiated LiF crystals and thin films for luminescent solid state detectors

    International Nuclear Information System (INIS)

    Piccinini, M; Ambrosini, F; Ampollini, A; Bonfigli, F; Libera, S; Picardi, L; Ronsivalle, C; Vincenti, M A; Montereali, R M

    2015-01-01

    Proton beams of 3 MeV energy, produced by the injector of a linear accelerator for proton therapy, were used to irradiate at room temperature lithium fluoride crystals and polycrystalline thin films grown by thermal evaporation. The irradiation fluence range was 10 11 -10 15 protons/cm 2 . The proton irradiation induced the stable formation of primary and aggregate color centers. Their formation was investigated by optical absorption and photoluminescence spectroscopy. The F 2 and F 3 + photoluminescence intensities, carefully measured in LiF crystals and thin films, show linear behaviours up to different maximum values of the irradiation fluence, after which a quenching is observed, depending on the nature of the samples (crystals and films). The Principal Component Analysis, applied to the absorption spectra of colored crystals, allowed to clearly identify the formation of more complex aggregate defects in samples irradiated at highest fluences. (paper)

  8. Primary and aggregate color centers in proton irradiated LiF crystals and thin films for luminescent solid state detectors

    Science.gov (United States)

    Piccinini, M.; Ambrosini, F.; Ampollini, A.; Bonfigli, F.; Libera, S.; Picardi, L.; Ronsivalle, C.; Vincenti, M. A.; Montereali, R. M.

    2015-04-01

    Proton beams of 3 MeV energy, produced by the injector of a linear accelerator for proton therapy, were used to irradiate at room temperature lithium fluoride crystals and polycrystalline thin films grown by thermal evaporation. The irradiation fluence range was 1011-1015 protons/cm2. The proton irradiation induced the stable formation of primary and aggregate color centers. Their formation was investigated by optical absorption and photoluminescence spectroscopy. The F2 and F3+ photoluminescence intensities, carefully measured in LiF crystals and thin films, show linear behaviours up to different maximum values of the irradiation fluence, after which a quenching is observed, depending on the nature of the samples (crystals and films). The Principal Component Analysis, applied to the absorption spectra of colored crystals, allowed to clearly identify the formation of more complex aggregate defects in samples irradiated at highest fluences.

  9. Endodontic treatment and esthetic management of a primary double tooth with direct composite using silicone buildup guide

    Directory of Open Access Journals (Sweden)

    Vinaya Kumar Kulkarni

    2012-01-01

    Full Text Available Gemination and fusion are morphological dental anomalies, characterized by the formation of a clinically wide tooth. Gemination occurs when one tooth bud tries to divide, while fusion occurs if two buds unite. The terms double teeth, double formation, conjoined teeth, geminifusion, vicinifusion and dental twinning are often used to describe fusion and gemination. Double teeth are associated with clinical problems such as poor esthetics, spacing problems and caries susceptibility. Management of such cases requires a comprehensive knowledge of the clinical entity as well as the problems associated with it. This report presents a case of primary double tooth in a 6-year-old boy involving maxillary left central incisor. The anomalous tooth was carious and pulpally involved. This was treated conservatively by endodontic treatment and esthetic rehabilitation was done with direct composite restoration using a silicone buildup guide. The treated tooth was followed up until exfoliation.

  10. Reflection color filters of the three primary colors with wide viewing angles using common-thickness silicon subwavelength gratings.

    Science.gov (United States)

    Kanamori, Yoshiaki; Ozaki, Toshikazu; Hane, Kazuhiro

    2014-10-20

    We fabricated reflection color filters of the three primary colors with wide viewing angles using silicon two-dimensional subwavelength gratings on the same quartz substrate. The grating periods were 400, 340, and 300 nm for red, green, and blue filters, respectively. All of the color filters had the same grating thickness of 100 nm, which enabled simple fabrication of a color filter array. Reflected colors from the red, green, and blue filters under s-polarized white-light irradiation appeared in the respective colors at incident angles from 0 to 50°. By rigorous coupled-wave analysis, the dimensions of each color filter were designed, and the calculated reflectivity was compared with the measured reflectivity.

  11. Third-harmonic generation in silicon and photonic crystals of macroporous silicon in the spectral intermediate-IR range; Erzeugung der Dritten Harmonischen in Silizium und Photonischen Kristallen aus makroporoesem Silizium im spektralen mittleren IR-Bereich

    Energy Technology Data Exchange (ETDEWEB)

    Mitzschke, Kerstin

    2007-11-01

    Nonlinear optical spectroscopy is a powerful method to study surface or bulk properties of condensed matter. In centrosymmetric materials like silicon even order nonlinear optical processes are forbidden. Besides self-focussing or self phase modulation third-harmonic-generation (THG) is the simplest process that can be studied. This work demonstrates that THG is a adapted non-contact and non-invasive optical method to get information about bulk structures of silicon and Photonic crystals (PC), consisting of silicon. Until now most studies are done in the visible spectral range being limited by the linear absorption losses. So the extension of THG to the IR spectral range is extremely useful. This will allow the investigation of Photonic Crystals, where frequencies near a photonic bandgap are of special interest. 2D- photonic structures under investigation were fabricated via photoelectrochemical etching of the Si (100) wafer (thickness 500 {mu}m) receiving square and hexagonal arranged pores. The typical periodicity of the structures used is 2 {mu}m and the length of the pores reached to 400 {mu}m. Because of stability the photonic structures were superimposed on silicon substrate. The experimental set-up used for the THG experiments generates tuneable picosecond IR pulses (tuning range 1500-4000 cm{sup -1}). The IR-pulse hit the sample either perpendicular to the sample surface or under an angle {theta}. The sample can be rotated (f) around the surface normal. The generated third harmonic is analysed by a polarizer, spectrally filtered by a polychromator and registered by a CCD camera. The setup can be used either in transmission or in reflection mode. Optical transmission and reflection spectra of the Si bulk correspond well with the theoretical description, a 4-fold and a 8-fold dependencies of the azimuth angle resulting in the structure of the x{sup (3)}-tensor of (100)-Si. The situation changes dramatically if the PC with hexagonal structure is investigated

  12. A study of Channeling, Volume Reflection and Volume Capture of 3.35 - 14.0 GeV Electrons in a bent Silicon Crystal

    Energy Technology Data Exchange (ETDEWEB)

    Wistisen, T. N. [Aarhus Univ. (Denmark); Uggerhoj, U. I. [Aarhus Univ. (Denmark); Wienands, U. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Markiewicz, T. W. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Noble, R. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Benson, B. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Smith, T. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Bagli, E. [Univ. of Ferrara (Italy); Bandiera, L. [Univ. of Ferrara (Italy); Germogli, G. [Univ. of Ferrara (Italy); Guidi, V. [Univ. of Ferrara (Italy); Mazzolari, A. [Univ. of Ferrara (Italy); Holtzapple, R. [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States); Tucker, S. [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States)

    2015-12-03

    We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111) plane in a strongly bent quasi-mosaic silicon crystal. Additionally, these phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5 and 14.0 GeV with a crystal with bending radius of 0.15m, corresponding to curvatures of 0.070, 0.088, 0.13, 0.22 and 0.29 times the critical curvature respectively. We have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission and the widths of the distribution of channeled particles parallel and orthogonal to the plane.

  13. Leakage current suppression with a combination of planarized gate and overlap/off-set structure in metal-induced laterally crystallized polycrystalline-silicon thin-film transistors

    Science.gov (United States)

    Chae, Hee Jae; Seok, Ki Hwan; Lee, Sol Kyu; Joo, Seung Ki

    2018-04-01

    A novel inverted staggered metal-induced laterally crystallized (MILC) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) with a combination of a planarized gate and an overlap/off-set at the source-gate/drain-gate structure were fabricated and characterized. While the MILC process is advantageous for fabricating inverted staggered poly-Si TFTs, MILC TFTs reveal higher leakage current than TFTs crystallized by other processes due to their high trap density of Ni contamination. Due to this drawback, the planarized gate and overlap/off-set structure were applied to inverted staggered MILC TFTs. The proposed device shows drastic suppression of leakage current and pinning phenomenon by reducing the lateral electric field and the space-charge limited current from the gate to the drain.

  14. Microdefects revealed by X-ray diffusion scattering in Czochralski-growth dislocation-free silicon single crystals

    International Nuclear Information System (INIS)

    Bublik, B.T.; Zotov, N.M.

    1997-01-01

    Microdefects in the regions of Si crystals having different thermal history defined by growth conditions was studied by the X-ray diffuse scattering method on a triple crystal X-ray diffractometer. It was shown that in such crystals the microdefects with positive strength are prevalent. However, between the above indicated regions the defects with the strength of opposite sign prevail

  15. A study on the effect of silicon content on mechanical properties

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  16. Focused ion beam scan routine, dwell time and dose optimizations for submicrometre period planar photonic crystal components and stamps in silicon

    International Nuclear Information System (INIS)

    Hopman, Wico C L; Ay, Feridun; Hu, Wenbin; Gadgil, Vishwas J; Kuipers, Laurens; Pollnau, Markus; Ridder, Rene M de

    2007-01-01

    Focused ion beam (FIB) milling is receiving increasing attention for nanostructuring in silicon (Si). These structures can for example be used for photonic crystal structures in a silicon-on-insulator (SOI) configuration or for moulds which can have various applications in combination with imprint technologies. However, FIB fabrication of submicrometre holes having perfectly vertical sidewalls is still challenging due to the redeposition effect in Si. In this study we show how the scan routine of the ion beam can be used as a sidewall optimization parameter. The experiments have been performed in Si and SOI. Furthermore, we show that sidewall angles as small as 1.5 0 are possible in Si membranes using a spiral scan method. We investigate the effect of the dose, loop number and dwell time on the sidewall angle, interhole milling and total milling depth by studying the milling of single and multiple holes into a crystal. We show that the sidewall angles can be as small as 5 0 in (bulk) Si and SOI when applying a larger dose. Finally, we found that a relatively large dwell time of 1 ms and a small loop number is favourable for obtaining vertical sidewalls. By comparing the results with those obtained by others, we conclude that the number of loops at a fixed dose per hole is the parameter that determines the sidewall angle and not the dwell time by itself

  17. High-Q energy trapping of temperature-stable shear waves with Lamé cross-sectional polarization in a single crystal silicon waveguide

    Science.gov (United States)

    Tabrizian, R.; Daruwalla, A.; Ayazi, F.

    2016-03-01

    A multi-port electrostatically driven silicon acoustic cavity is implemented that efficiently traps the energy of a temperature-stable eigen-mode with Lamé cross-sectional polarization. Dispersive behavior of propagating and evanescent guided waves in a ⟨100⟩-aligned single crystal silicon waveguide is used to engineer the acoustic energy distribution of a specific shear eigen-mode that is well known for its low temperature sensitivity when implemented in doped single crystal silicon. Such an acoustic energy trapping in the central region of the acoustic cavity geometry and far from substrate obviates the need for narrow tethers that are conventionally used for non-destructive and high quality factor (Q) energy suspension in MEMS resonators; therefore, the acoustically engineered waveguide can simultaneously serve as in-situ self-oven by passing large uniformly distributed DC currents through its body and without any concern about perturbing the mode shape or deforming narrow supports. Such a stable thermo-structural performance besides large turnover temperatures than can be realized in Lamé eigen-modes make this device suitable for implementation of ultra-stable oven-controlled oscillators. 78 MHz prototypes implemented in arsenic-doped single crystal silicon substrates with different resistivity are transduced by in- and out-of-plane narrow-gap capacitive ports, showing high Q of ˜43k. The low resistivity device shows an overall temperature-induced frequency drift of 200 ppm over the range of -20 °C to 80 °C, which is ˜15× smaller compared to overall frequency drift measured for the similar yet high resistivity device in the same temperature range. Furthermore, a frequency tuning of ˜2100 ppm is achieved in high resistivity device by passing 45 mA DC current through its body. Continuous operation of the device under such a self-ovenizing current over 10 days did not induce frequency instability or degradation in Q.

  18. The combined effect of titanic carbide and aluminum phosphide on the refinement of primary silicon in Al-50Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dai Hongshang [Key Lab. of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong Univ., Jinan (China); Liu Xiangfa [Key Lab. of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong Univ., Jinan (China); Shandong Binzhou Bohai Piston Co., Ltd., Binzhou, SD (China)

    2008-12-15

    Two refinement methods for Al-50Si alloy are presented in this article: one way is using a newly developed Si-20P alloy at 1573 K: another technique is using the Si-20P alloy in company with Al-TiO{sub 2}-C mixture powder at 1473 K. Compared to the first method, the second one not only has better refinement effect on primary Si but also lower refinement temperature. These results are due to the combined effect of TiC and AlP on the refinement process, and the duplex TiC/AlP nucleus of primary silicon has been demonstrated using electron probe micro-analysis. Moreover, the reaction of Al-TiO{sub 2}-C mixture powder with increasing temperature was investigated using differential scanning calorimetry, which shows that the TiC particles are produced at about 1473 K. AlP particles combine with the in-situ TiC particles in the melt, which is the main reason for the formation of a duplex nucleus, and the disregistry between TiC and AlP in low-index planes is also discussed. (orig.)

  19. Silicon web process development

    Science.gov (United States)

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

    1981-01-01

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

  20. Development of practical application technology for photovoltaic power generation systems in fiscal 1997. Development of technologies to manufacture application type thin film solar cells with new structure (development of technologies to manufacture amorphous silicon and thin film poly-crystal silicon hybrid thin film solar cells); 1997 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu. Usumaku taiyo denchi no seizo gijutsu kaihatsu, oyogata shinkozo usumaku taiyo denchi no seizo gijutsu kaihatsu (amorphous silicon/usumaku takessho silicon hybrid usumaku taiyo denchi no seizo gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Research and development was performed with an objective to manufacture amorphous silicon and thin film poly-crystal silicon hybrid solar cells with large area and at low cost, being a high-efficiency next generation solar cell. The research was performed based on a principle that low-cost substrates shall be used, that a manufacturing process capable of forming amorphous silicon films with large area shall be based on, and that silicon film with as thin as possible thickness shall be used. Fiscal 1997 has started research and development on making the cells hybrid with amorphous silicon cells. As a result of the research and development, such achievements have been attained as using texture structure on the rear layer in thin poly-crystal silicon film solar cells with a thickness of two microns, and having achieved conversion efficiency of 10.1% by optimizing the junction interface forming conditions. A photo-deterioration test was carried out on hybrid cells which combine the thin poly-crystal silicon film cells having STAR structure with the amorphous silicon cells. Stabilization efficiency of 11.5% was attained after light has been irradiated for 500 hours or longer. (NEDO)

  1. Pilonidal sinus disease surgery in children: the first study to compare crystallized phenol application to primary excision and closure.

    Science.gov (United States)

    Ates, Ufuk; Ergun, Ergun; Gollu, Gulnur; Sozduyar, Sumeyye; Kologlu, Meltem; Cakmak, Murat; Dindar, Huseyin; Yagmurlu, Aydin

    2018-03-01

    Pilonidal sinus (PS) is an infectious and inflammatory disease of sacrococcygeal region. Current methods include; surgical excision with/without suturing the defect, rhomboid excision and flap and chemical substance application. In this study, crystallized phenol application was compared to excision and primary closure. This retrospective study included pediatric patients with PS who were treated with excision and primer closure technique and phenol application. The patients' medical data were analyzed retrospectively. This study included 117 patients with PS. There were 52 girls (44%) and 65 boys (56%). Mean age of children was 15.6 (12-20) years. Excision and primary closure were applied to 77 patients (66%) and phenol was applied to 40 patients (34%). The children in phenol group were discharged on the operation day; mean hospitalization time in the excision and primary closure group was 2.7 (1-14) days. Mean follow up was 44.6 (8-82) months for primary excision and closure group and 8.1 (1-19) months for phenol group. Although many surgical and non-surgical treatment modalities have been described for PS, the optimal one remains unknown. Limited with the retrospective nature of the data, crystallized phenol application seems a feasible minimal invasive alternative to primary closure of PS with lower recurrence and complication rates in children. Level III. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. FY 1977 Annual report on Sunshine Project results. Research and development of photovoltaic power generation systems (Research and development of vertically drawn ribbon crystals of silicon); 1977 nendo taiyoko hatsuden system no kenkyu kaihatsu seika hokokusho. Silicon tatehiki ribon kessho no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1978-03-31

    This project is aimed at establishment of ribbon crystal production techniques and development of photovoltaic power generation systems incorporating the ribbon crystals, in order to greatly reduce cost of photovoltaic power generation systems. The research efforts in this fiscal year is focused on development of the techniques for continuously growing the ribbons, to attain the above goal by accelerating growth of the ribbon crystals in unit time and clarifying, in the early stage, the problems to be solved before commercializing the ribbon crystals for the future solar cells. The major research results are (1) development of the method for vertically drawing ribbon crystals of silicon, and (2) analysis of the vertically drawn ribbon crystals of silicon. For the item (1), the technological development efforts are focused on continuously drawing mechanisms and furnace for continuous drawing, with the structural studies as the center for the former and solution of heat-related problems for the latter, which eventually lead to development of a 800 mm long ribbon crystal passing over the roll. For the item (2), the crystal structure is analyzed by the electron channeling pattern method. The results suggest that use of a p-type substrate can improve average efficiency of the ribbon crystal type solar cell. (NEDO)

  3. FY 1979 Annual report on Sunshine Project results. Research and development of photovoltaic power generation systems (Research and development of vertically drawn ribbon crystals of silicon); 1979 nendo taiyoko hatsuden system no kenkyu kaihatsu seika hokokusho. Silicon tatehiki ribon kessho no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-03-01

    The efforts in this fiscal year for development of methods for vertically drawing ribbon crystals of silicon are directed to the following items, in order to further improve the techniques for vertically drawing two or more ribbon crystals on a continuous basis, developed in the previous fiscal year: (1) tests of the drawing apparatus, developed in the previous fiscal year, to deepen the techniques for drawing the ribbon crystals, (2) modification of the above apparatus to further develop the apparatus for vertically drawing two or more ribbon crystals on a continuous basis, (3) comparison of drawing a single ribbon crystal, conducted separately, with drawing two or more ribbon crystals, to clarify the problems involved in the latter, and (4) basic investigations on the materials for the furnace internals exposed to high temperature, other than the carbon material used at present. The vertically drawn ribbon crystals of silicon is investigated, based on the results obtained in the previous fiscal year that ribbon crystal quality depends on impurities present therein, mainly for (1) quantitative analysis of the impurity elements present in the ribbon crystal, (2) relationship between impurity elements and characteristics of the solar cells made on a trial basis, and (3) investigations on local concentration of the impurity elements. (NEDO)

  4. The investigations of beam extraction and collimation at U-70 proton synchrotron of IHEP by using short silicon crystals

    CERN Document Server

    Afonine, A G; Biryukov, V M; Breese, M B H; Chepegin, V N; Chesnokov, Yu A; Drees, A; Fedotov, Y S; Guidi, V; Kotov, V I; Maisheev, V A; Martinelli, G; Scandale, Walter; Stefancich, M; Terekhov, V I; Trbojevic, D; Troyanov, E F; Vincenzi, D

    2002-01-01

    The new results of using short (2-4 mm) bent crystals for extraction and collimation of proton beam at IHEP 70 GeV proton synchrotron are reported. A broad range of energies from 6 to 65 GeV has been studied in the same crystal collimation set-up where earlier the extraction efficiency of 85% was obtained for 70 GeV protons using a 2-mm Si crystal. The new regime of extraction is applied now at the accelerator to deliver the beam for different experimental setups within the range of intensity 10E7-10E12ppp. (6 refs).

  5. The Investigations Of Beam Extraction And Collimation At U-70 Proton Synchrotron Of IHEP By Using Short Silicon Crystals

    CERN Document Server

    Afonine, A.G.; Biryukov, V.M.; Chepegin, V.N.; Chesnokov, Y.A.; Fedotov, Y.S.; Kotov, V.I.; Maisheev, V.A.; Terekhov, V.I.; Troyanov, E.F.; Drees, A.; Trbojevic, D.; Scandale, W.; Breese, M.B.H.; Guidi, V.; Martinelli, G.; Stefancich, M.; Vincenzi, D.

    2002-01-01

    The new results of using short (2-4mm) bent crystals for extraction and collimation of proton beam at IHEP 70 Gev proton synchrotron are reported. A broad range of energies from 6 to 65 GeV has been studied in the same crystal collimation set-up. The efficiency of extraction more than 85% and intensity more than 10E12 were obtained by using crystal with the length 2-mm and the angle 1 mrad. The new regime of extraction is applied now at the accelerator to deliver the beam for different experimental setups within the range of intensity 10E7-10E12ppp.

  6. Structural, elastic and electronic Properties of isotropic cubic crystals of carbon and silicon nanotubes : Density functional based tight binding calculations.

    Directory of Open Access Journals (Sweden)

    Alexander L. Ivanovskii

    2008-01-01

    Full Text Available Atomic models of cubic crystals (CC of carbon and graphene-like Si nanotubes are offered and their structural, cohesive, elastic and electronic properties are predicted by means of the DFTB method. Our main findings are that the isotropic crystals of carbon nanotubes adopt a very high elastic modulus B and low compressibility β, namely B = 650 GPa, β = 0.0015 1/GPa. In addition, these crystals preserve the initial conductivity type of their “building blocks”, i.e. isolated carbon and Si nanotubes. This feature may be important for design of materials with the selected conductivity type.

  7. Effect of laser-plasma X-ray irradiation on crystallization of amorphous silicon film by excimer laser annealing

    International Nuclear Information System (INIS)

    Matsuo, Naoto; Uejukkoku, Kazuya; Heya, Akira; Takanashi, Yasuyuki; Amano, Sho; Miyamoto, Shuji; Mochizuki, Takayasu

    2007-01-01

    The effect of laser plasma soft X-ray (LPX) irradiation on crystallization by excimer laser annealing (ELA) was investigated at low ELA energy densities. The crystalline fraction at energy densities of 50 and 60 mJ/cm 2 for LPX followed by ELA is nearly equal to that at 80 to 100 mJ/cm 2 for the ELA method with non-LPX irradiation. The results obtained indicate that LPX irradiation before ELA reduces the critical energy density for the start of crystallization. The combined method of LPX irradiation and ELA will enable us to realize a low-temperature process for ELA crystallization. (author)

  8. Modeling the Deflection of Polarized Electrons with Energies in the Range 3.35-14 GeV in a Bent Silicon Crystal

    Science.gov (United States)

    Koshcheev, V. P.; Shtanov, Yu. N.; Morgun, D. A.; Panina, T. A.

    2018-04-01

    The evolution of the magnetic moment of a relativistic particle is described with the help of the Bargmann-Michel-Telegdi equation in the planar channels of a bent silicon crystal with allowance for multiple scatteringboth along and transverse to the (111) atomic plane, which consists of chains. Results of numerical simulations demonstrate a strong dependence of the degree of depolarization of the electron beam on the energy since at the energies 3.35 and 4.2 GeV the maximum in the distribution over rotation angles of the electron spin is absent, and at energies from 6.3 to 14 GeV the position of the maximum is in line with the theoretical estimate obtained using the formula of V. L. Lyuboshits.

  9. Continuous-wave operation and 10-Gb/s direct modulation of InAsP/InP sub-wavelength nanowire laser on silicon photonic crystal

    Directory of Open Access Journals (Sweden)

    Masato Takiguchi

    2017-04-01

    Full Text Available We demonstrated sub-wavelength (∼111 nm diameter single nanowire (NW continuous wave (CW lasers on silicon photonic crystal in the telecom-band with direct modulation at 10 Gb/s by optical pumping at cryogenic temperatures. To estimate the small signal response and pseudo-random bit sequence (PRBS modulation of our CW lasers, we employed a new signal detection technique that employs a superconducting single photon detector and a time-correlated single photon counting module. The results showed that our NW laser was unambiguously modulated at above 10 Gb/s and an open eye pattern was obtained. This is the first demonstration of a telecom-band CW NW laser with high-speed PRBS modulation.

  10. Formation of different micro-morphologies from VO2 and ZnO crystallization using macro-porous silicon substrates

    Science.gov (United States)

    Salazar-Kuri, U.; Antúnez, E. E.; Estevez, J. O.; Olive-Méndez, Sion F.; Silva-González, N. R.; Agarwal, V.

    2017-05-01

    Square-shaped macropores produced by electrochemical anodization of n- and p-type Si wafers have been used as centers of nucleation to crystallize VO2 and ZnO. Substrate roughness dependent formation of different morphologies is revealed in the form of squared particles, spheres, bars and ribbons in the case of VO2 and hexagonal piles and spheres in the case of ZnO, have been observed.The presence of nano-/micro-metric crystals was studied through field emission scanning electron microscopy and energy dispersive X-ray spectroscopy mapping. Crystal structure of metal oxides was confirmed by micro-Raman spectroscopy. The growth of the different morphologies has been explained in terms of the surface free energy of a bare Si/SiO2 substrate and its modification originated from the roughness of the surface and of the walls of the porous substrates. This energy plays a crucial role on the minimization of the required energy to induce heterogeneous nucleation and crystal growth. Present work strengthens and provides an experimental evidence of roughness dependent metal oxide crystal growth with well-defined habits from pore corners and rough sides of the pore walls, similar to already reported protein crystals.

  11. Amorphous silicon crystallization by laser. Report of the experiments at Frascati (Project Foto); Cristallizzazione di silicio amorfo via laser. Rapporto degli esperimenti a frascati (Progetto Foto)

    Energy Technology Data Exchange (ETDEWEB)

    Bollanti, S; Di Lazzaro, P; Murra, D [ENEA, Centro Ricerche Frascati, Frascati, RM (Italy). Div. Fisica Applicata; Imparato, A; Privato, C [ENEA, Centro Ricerche Portici, Naples (Italy). Div. Fonti Rinnovabili; Carluccio, R; Fortunato, G; Mariucci, L; Pecora, A [CNR Istituto di Elettronica dello Stato Solido, Rome (Italy)

    2000-07-01

    The final goal of the Project FOTO is the construction of a laboratory in a clean room for the production of active matrix which can be used to obtain Active Matrix Liquid Crystal Displays (AMLCD). The AMLCD are based on Thin Film Transistors (TFT), which can be obtained by poly-silicon (poly-Si) thin films, achieved, e.g., by irradiating films of amorphous silicon (a-Si) by ultraviolet laser radiation. In this report, are presented the results of the a-Si irradiation by using the laser-facility Hercules (excimer XeCl, l=0,308 mm) done at the ENEA Frascati Centre. The transformation of a-Si into poly-Si is commented upon the variation of the space-time characteristics of the laser pulses, of the irradiation conditions and of the characteristics of the irradiated a-Si films. [Italian] Il macro-obiettivo del Progetto FOTO e' la realizzazione di un laboratorio in camera pulita per lo sviluppo di processi atti a fabbricare matrici attive utilizzabili per ottenere schermi piatti a cristalli liquidi (AMLCD, Active Matrix Liquid Crystal Display). Uno dei primi passi del processo consiste nel creare transistori a film sottile (TFT, Thin Film Transistor). A tal fine, e' necessario ottenere strati sottili di Silicio policristallino irragiando films di silicio amorfo con luce laser ultravioletta. In questo rapporto, sono presentati i risultati degli irraggiamenti di film sottili di silicio amorfo tramite la laser-facility Hercules (eccimero XeCl, l=0,308 mm) effettuati presso il C.R. ENEA di Frascati. La trasformazione di silicio amorfo in silicio policristallino cosi' ottenuta e' commentata al variare delle caratteristiche spazio-temporali dell'impulso laser, delle condizioni di irraggiamento e delle caratteristiche del film di silicio amorfo irraggiato.

  12. Amorphous silicon crystallization by laser. Report of the experiments at Frascati (Project Foto); Cristallizzazione di silicio amorfo via laser. Rapporto degli esperimenti a frascati (Progetto Foto)

    Energy Technology Data Exchange (ETDEWEB)

    Bollanti, S.; Di Lazzaro, P.; Murra, D. [ENEA, Centro Ricerche Frascati, Frascati, RM (Italy). Div. Fisica Applicata; Imparato, A.; Privato, C. [ENEA, Centro Ricerche Portici, Naples (Italy). Div. Fonti Rinnovabili; Carluccio, R.; Fortunato, G.; Mariucci, L.; Pecora, A. [CNR Istituto di Elettronica dello Stato Solido, Rome (Italy)

    2000-07-01

    The final goal of the Project FOTO is the construction of a laboratory in a clean room for the production of active matrix which can be used to obtain Active Matrix Liquid Crystal Displays (AMLCD). The AMLCD are based on Thin Film Transistors (TFT), which can be obtained by poly-silicon (poly-Si) thin films, achieved, e.g., by irradiating films of amorphous silicon (a-Si) by ultraviolet laser radiation. In this report, are presented the results of the a-Si irradiation by using the laser-facility Hercules (excimer XeCl, l=0,308 mm) done at the ENEA Frascati Centre. The transformation of a-Si into poly-Si is commented upon the variation of the space-time characteristics of the laser pulses, of the irradiation conditions and of the characteristics of the irradiated a-Si films. [Italian] Il macro-obiettivo del Progetto FOTO e' la realizzazione di un laboratorio in camera pulita per lo sviluppo di processi atti a fabbricare matrici attive utilizzabili per ottenere schermi piatti a cristalli liquidi (AMLCD, Active Matrix Liquid Crystal Display). Uno dei primi passi del processo consiste nel creare transistori a film sottile (TFT, Thin Film Transistor). A tal fine, e' necessario ottenere strati sottili di Silicio policristallino irragiando films di silicio amorfo con luce laser ultravioletta. In questo rapporto, sono presentati i risultati degli irraggiamenti di film sottili di silicio amorfo tramite la laser-facility Hercules (eccimero XeCl, l=0,308 mm) effettuati presso il C.R. ENEA di Frascati. La trasformazione di silicio amorfo in silicio policristallino cosi' ottenuta e' commentata al variare delle caratteristiche spazio-temporali dell'impulso laser, delle condizioni di irraggiamento e delle caratteristiche del film di silicio amorfo irraggiato.

  13. Sub-Micrometer Zeolite Films on Gold-Coated Silicon Wafers with Single-Crystal-Like Dielectric Constant and Elastic Modulus

    Energy Technology Data Exchange (ETDEWEB)

    Tiriolo, Raffaele [Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Rangnekar, Neel [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Zhang, Han [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Shete, Meera [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Bai, Peng [Department of Chemistry and Chemistry Theory Center, University of Minnesota, 207 Pleasant St SE Minneapolis MN 55455 USA; Nelson, John [Characterization Facility, University of Minnesota, 12 Shepherd Labs, 100 Union St. S.E. Minneapolis MN 55455 USA; Karapetrova, Evguenia [Surface Scattering and Microdiffraction, X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Ave, Building 438-D002 Argonne IL 60439 USA; Macosko, Christopher W. [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Siepmann, Joern Ilja [Department of Chemistry and Chemistry Theory Center, University of Minnesota, 207 Pleasant St SE Minneapolis MN 55455 USA; Lamanna, Ernesto [Department of Health Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Lavano, Angelo [Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Tsapatsis, Michael [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA

    2017-05-08

    A low-temperature synthesis coupled with mild activation produces zeolite films exhibiting low dielectric constant (low-k) matching the theoretically predicted and experimentally measured values for single crystals. This synthesis and activation method allows for the fabrication of a device consisting of a b-oriented film of the pure-silica zeolite MFI (silicalite-1) supported on a gold-coated silicon wafer. The zeolite seeds are assembled by a manual assembly process and subjected to optimized secondary growth conditions that do not cause corrosion of the gold underlayer, while strongly promoting in-plane growth. The traditional calcination process is replaced with a non-thermal photochemical activation to ensure preservation of an intact gold layer. The dielectric constant (k), obtained through measurement of electrical capacitance in a metal-insulator-metal configuration, highlights the ultralow k approximate to 1.7 of the synthetized films, which is among the lowest values reported for an MFI film. There is large improvement in elastic modulus of the film (E approximate to 54 GPa) over previous reports, potentially allowing for integration into silicon wafer processing technology.

  14. Depth-of-interaction measurement in a single-layer crystal array with a single-ended readout using digital silicon photomultiplier

    International Nuclear Information System (INIS)

    Lee, Min Sun; Lee, Jae Sung

    2015-01-01

    We present the first experimental evaluation of a depth-of-interaction (DOI) positron emission tomography (PET) detector using a digital silicon photomultiplier (dSiPM). To measure DOI information from a mono-layer array of scintillation crystals with a single-ended readout, our group has previously proposed and developed a new method based on light spread using triangular reflectors. Since this method relies on measurement of the light distribution, dSiPM, which has a fully digital interface, has several merits for our DOI measurement. The DOI PET detector comprised of a dSiPM sensor (DPC-3200-22-44) coupled with a 14   ×   14 array of 2 mm  ×  2 mm  ×  20 mm unpolished LGSO crystals. All crystals were covered with triangular reflectors. To obtain a good performance of the DOI PET detector, several parameters of detector were selected as a preliminary experiment. Detector performance was evaluated with the selected parameters and the optimal experimental setup, and a DOI measurement was conducted by irradiating the crystal block at five DOI positions spaced at intervals of 4 mm. Maximum-likelihood estimation was employed for DOI positioning and the optimal DOI estimation scheme was also investigated in this study. As a result, the DOI PET detector showed clear crystal identification. The energy resolution (full-width at half-maximum (FWHM)) averaged over all depths was 10.21%  ±  0.15% at 511 keV, and time resolution averaged over all depths was 1198.61   ±   39.70 ps FWHM. The average DOI positioning accuracy for all depths was 74.22%  ±  6.77%, which equates to DOI resolution of 4.67 mm. Energy and DOI resolutions were uniform over all crystal positions except for the back parts of the array. Furthermore, additional simulation studies were conducted to verify the results of our DOI measurement method that is combined with dSiPM technology. In conclusion, our continuous DOI PET detector

  15. Method of forming buried oxide layers in silicon

    Science.gov (United States)

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2000-01-01

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

  16. Elite silicon and solar power

    International Nuclear Information System (INIS)

    Yasamanov, N.A.

    2000-01-01

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

  17. Effect of deposition temperature on electron-beam evaporated polycrystalline silicon thin-film and crystallized by diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J., E-mail: j.yun@unsw.edu.au; Varalmov, S.; Huang, J.; Green, M. A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Kim, K. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Suntech R and D Australia, Botany, New South Wales 2019 (Australia)

    2014-06-16

    The effects of the deposition temperature on the microstructure, crystallographic orientation, and electrical properties of a 10-μm thick evaporated Si thin-film deposited on glass and crystallized using a diode laser, are investigated. The crystallization of the Si thin-film is initiated at a deposition temperature between 450 and 550 °C, and the predominant (110) orientation in the normal direction is found. Pole figure maps confirm that all films have a fiber texture and that it becomes stronger with increasing deposition temperature. Diode laser crystallization is performed, resulting in the formation of lateral grains along the laser scan direction. The laser power required to form lateral grains is higher in case of films deposited below 450 °C for all scan speeds. Pole figure maps show 75% occupancies of the (110) orientation in the normal direction when the laser crystallized film is deposited above 550 °C. A higher density of grain boundaries is obtained when the laser crystallized film is deposited below 450 °C, which limits the solar cell performance by n = 2 recombination, and a performance degradation is expected due to severe shunting.

  18. Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

    International Nuclear Information System (INIS)

    Gontad, F.; Conde, J.C.; Filonovich, S.; Cerqueira, M.F.; Alpuim, P.; Chiussi, S.

    2013-01-01

    We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p + -nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm 2 is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm 2 promote partial crystallization of the amorphous structures

  19. Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Gontad, F., E-mail: fran_gontad@yahoo.es [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Conde, J.C. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Filonovich, S.; Cerqueira, M.F.; Alpuim, P. [Department of Physics, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); Chiussi, S. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain)

    2013-06-01

    We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p{sup +}-nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm{sup 2} is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm{sup 2} promote partial crystallization of the amorphous structures.

  20. Selective formation of porous silicon

    Science.gov (United States)

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

    1993-01-01

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

  1. High-Performance Flexible Thin-Film Transistors Based on Single-Crystal-like Silicon Epitaxially Grown on Metal Tape by Roll-to-Roll Continuous Deposition Process.

    Science.gov (United States)

    Gao, Ying; Asadirad, Mojtaba; Yao, Yao; Dutta, Pavel; Galstyan, Eduard; Shervin, Shahab; Lee, Keon-Hwa; Pouladi, Sara; Sun, Sicong; Li, Yongkuan; Rathi, Monika; Ryou, Jae-Hyun; Selvamanickam, Venkat

    2016-11-02

    Single-crystal-like silicon (Si) thin films on bendable and scalable substrates via direct deposition are a promising material platform for high-performance and cost-effective devices of flexible electronics. However, due to the thick and unintentionally highly doped semiconductor layer, the operation of transistors has been hampered. We report the first demonstration of high-performance flexible thin-film transistors (TFTs) using single-crystal-like Si thin films with a field-effect mobility of ∼200 cm 2 /V·s and saturation current, I/l W > 50 μA/μm, which are orders-of-magnitude higher than the device characteristics of conventional flexible TFTs. The Si thin films with a (001) plane grown on a metal tape by a "seed and epitaxy" technique show nearly single-crystalline properties characterized by X-ray diffraction, Raman spectroscopy, reflection high-energy electron diffraction, and transmission electron microscopy. The realization of flexible and high-performance Si TFTs can establish a new pathway for extended applications of flexible electronics such as amplification and digital circuits, more than currently dominant display switches.

  2. Large aperture deformable mirror with a transferred single-crystal silicon membrane actuated using large-stroke PZT Unimorph Actuators

    Science.gov (United States)

    Hishinumat, Yoshikazu; Yang, Eui - Hyeok (EH)

    2005-01-01

    We have demonstrated a large aperture (50 mm x 50 mm) continuous membrane deformable mirror (DM) with a large-stroke piezoelectric unimorph actuator array. The DM consists of a continuous, large aperture, silicon membrane 'transferred' in its entirety onto a 20 x 20 piezoelectric unimorph actuator array. A PZT unimorph actuator, 2.5 mm in diameter with optimized PZT/Si thickness and design showed a deflection of 5.7 [m at 20V. An assembled DM showed an operating frequency bandwidth of 30 kHz and influence function of approximately 30%.

  3. Fabrication of three-dimensional MIS nano-capacitor based on nano-imprinted single crystal silicon nanowire arrays

    KAUST Repository

    Zhai, Yujia; Palard, Marylene; Mathew, Leo; Hussain, Muhammad Mustafa; Willson, Grant Grant; Tutuc, Emanuel; Banerjee, Sanjay Kumar

    2012-01-01

    We report fabrication of single crystalline silicon nanowire based-three-dimensional MIS nano-capacitors for potential analog and mixed signal applications. The array of nanowires is patterned by Step and Flash Imprint Lithography (S-FIL). Deep silicon etching (DSE) is used to form the nanowires with high aspect ratio, increase the electrode area and thus significantly enhance the capacitance. High-! dielectric is deposited by highly conformal atomic layer deposition (ALD) Al2O3 over the Si nanowires, and sputtered metal TaN serves as the electrode. Electrical measurements of fabricated capacitors show the expected increase of capacitance with greater nanowire height and decreasing dielectric thickness, consistent with calculations. Leakage current and time-dependent dielectric breakdown (TDDB) are also measured and compared with planar MIS capacitors. In view of greater interest in 3D transistor architectures, such as FinFETs, 3D high density MIS capacitors offer an attractive device technology for analog and mixed signal applications. - See more at: http://www.eurekaselect.com/105099/article#sthash.EzeJxk6j.dpuf

  4. Fabrication of three-dimensional MIS nano-capacitor based on nano-imprinted single crystal silicon nanowire arrays

    KAUST Repository

    Zhai, Yujia

    2012-11-26

    We report fabrication of single crystalline silicon nanowire based-three-dimensional MIS nano-capacitors for potential analog and mixed signal applications. The array of nanowires is patterned by Step and Flash Imprint Lithography (S-FIL). Deep silicon etching (DSE) is used to form the nanowires with high aspect ratio, increase the electrode area and thus significantly enhance the capacitance. High-! dielectric is deposited by highly conformal atomic layer deposition (ALD) Al2O3 over the Si nanowires, and sputtered metal TaN serves as the electrode. Electrical measurements of fabricated capacitors show the expected increase of capacitance with greater nanowire height and decreasing dielectric thickness, consistent with calculations. Leakage current and time-dependent dielectric breakdown (TDDB) are also measured and compared with planar MIS capacitors. In view of greater interest in 3D transistor architectures, such as FinFETs, 3D high density MIS capacitors offer an attractive device technology for analog and mixed signal applications. - See more at: http://www.eurekaselect.com/105099/article#sthash.EzeJxk6j.dpuf

  5. Preparation, crystallization, and preliminary X-ray diffraction study of mutant carboxypeptidase T containing the primary specificity pocket of carboxypeptidase B

    International Nuclear Information System (INIS)

    Akparov, V. Kh.; Grishin, A. M.; Timofeev, V. I.; Kuranova, I. P.

    2010-01-01

    Recombinant G215S, A251G, T257A, D260G, T262D mutant carboxypeptidase T from Thermoactinomyces vulgaris containing mutations in the primary specificity pocket was prepared and crystallized. Single crystals with a size of up to 0.3 mm were grown and investigated by X-ray diffraction. Recombinant mutant carboxypeptidase T containing the primary specificity subsite compositionally identical to that of pancreatic carboxypeptidase B crystallizes in the same space group as the natural enzyme. The crystals belong to sp. gr. P6 3 22; the unit-cell parameters are a = b = 157.867 A, c = 104.304 A, α = β = 90 deg., γ = 120 deg. X-ray diffraction data suitable for determining the three-dimensional structure at atomic resolution were collected from one crystal.

  6. Three-dimensional study of the pressure field and advantages of hemispherical crucible in silicon Czochralski crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, F. [LTSE Laboratory, University of Science and Technol., USTHB BP 32 Elalia, Babezzouar, Algiers (Algeria); University Mouloud Mammeri, Tizi Ouzou (Algeria); Merah, A. [University M' hammed Bougara, Boumerdes (Algeria); Zizi, M. [LTSE Laboratory, University of Science and Technol., USTHB BP 32 Elalia, Babezzouar, Algiers (Algeria); Hanchi, S. [UER Mecanique/ E.M.P B.P 17 Bordj El Bahri, Algiers (Algeria); Alemany, A. [Laboratoire EPM, CNRS, Grenoble (France); Bouabdallah, A.

    2010-06-15

    The effects of several growth parameters in cylindrical and spherical Czochralski crystal process are studied numerically and particularly, we focus on the influence of the pressure field. We present a set of three-dimensional computational simulations using the finite volume package Fluent in two different geometries, a new geometry as cylindro-spherical and the traditional configuration as cylindro-cylindrical. We found that the evolution of pressure which is has not been studied before; this important function is strongly related to the vorticity in the bulk flow, the free surface and the growth interface. It seems that the pressure is more sensitive to the breaking of symmetry than the other properties that characterize the crystal growth as temperature or velocity fields. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. An all-silicon laser by coupling between electronic localized states and defect states of photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Huang Weiqi, E-mail: WQHuang2001@yahoo.com [Institute of Nanophotonic Physics, Key Laboratory of Photoelectron Technology and Application, Guizhou University, Guiyang 550025 (China); Huang Zhongmei; Miao Xinjiang; Cai Chenlan; Liu Jiaxin; Lue Quan [Institute of Nanophotonic Physics, Key Laboratory of Photoelectron Technology and Application, Guizhou University, Guiyang 550025 (China); Liu Shirong, E-mail: Shirong@yahoo.com [State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550003 (China); Qin Chaojian [State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550003 (China)

    2012-01-15

    In a nano-laser of Si quantum dots (QD), the smaller QD fabricated by nanosecond pulse laser can form the pumping level tuned by the quantum confinement (QC) effect. Coupling between the active centers formed by localized states of surface bonds and the two-dimensional (2D) photonic crystal is used to select model in the nano-laser. The experimental demonstration is reported in which the peaks of stimulated emission at about 600 nm and 700 nm were observed on the Si QD prepared in oxygen after annealing which improves the stimulated emission. It is interesting to make a comparison between the localized electronic states in gap due to defect formed by surface bonds and the localized photonic states in gap of photonic band due to defect of 2D photonic crystal.

  8. Analysis of polytype stability in PVT grown silicon carbide single crystal using competitive lattice model Monte Carlo simulations

    Directory of Open Access Journals (Sweden)

    Hui-Jun Guo

    2014-09-01

    Full Text Available Polytype stability is very important for high quality SiC single crystal growth. However, the growth conditions for the 4H, 6H and 15R polytypes are similar, and the mechanism of polytype stability is not clear. The kinetics aspects, such as surface-step nucleation, are important. The kinetic Monte Carlo method is a common tool to study surface kinetics in crystal growth. However, the present lattice models for kinetic Monte Carlo simulations cannot solve the problem of the competitive growth of two or more lattice structures. In this study, a competitive lattice model was developed for kinetic Monte Carlo simulation of the competition growth of the 4H and 6H polytypes of SiC. The site positions are fixed at the perfect crystal lattice positions without any adjustment of the site positions. Surface steps on seeds and large ratios of diffusion/deposition have positive effects on the 4H polytype stability. The 3D polytype distribution in a physical vapor transport method grown SiC ingot showed that the facet preserved the 4H polytype even if the 6H polytype dominated the growth surface. The theoretical and experimental results of polytype growth in SiC suggest that retaining the step growth mode is an important factor to maintain a stable single 4H polytype during SiC growth.

  9. Isolation of a 250 million-year-old halotolerant bacterium from a primary salt crystal

    Science.gov (United States)

    Vreeland, Russell H.; Rosenzweig, William D.; Powers, Dennis W.

    2000-10-01

    Bacteria have been found associated with a variety of ancient samples, however few studies are generally accepted due to questions about sample quality and contamination. When Cano and Borucki isolated a strain of Bacillus sphaericus from an extinct bee trapped in 25-30 million-year-old amber, careful sample selection and stringent sterilization techniques were the keys to acceptance. Here we report the isolation and growth of a previously unrecognized spore-forming bacterium (Bacillus species, designated 2-9-3) from a brine inclusion within a 250million-year-old salt crystal from the Permian Salado Formation. Complete gene sequences of the 16S ribosomal DNA show that the organism is part of the lineage of Bacillus marismortui and Virgibacillus pantothenticus. Delicate crystal structures and sedimentary features indicate the salt has not recrystallized since formation. Samples were rejected if brine inclusions showed physical signs of possible contamination. Surfaces of salt crystal samples were sterilized with strong alkali and acid before extracting brines from inclusions. Sterilization procedures reduce the probability of contamination to less than 1 in 10 9.

  10. Achievement report for fiscal 1997. Technological development for practical application of a solar energy power generation system /development of technology to manufacture solar cells/development of technology to manufacture thin film solar cells (development of technology to manufacture materials and substrates (development of technology to manufacture silicon crystal based high-quality materials and substrates)); 1997 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu seika hokokusho. Taiyo denchi seizo gijutsu kaihatsu, usumaku taiyo denchi seizo gijutsu kaihatsu, zairyo kiban seizo gijutsu kaihatsu (silicon kesshokei kohinshitsu zairyo kiban no seizo gujutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    It is intended to develop thin film solar cells capable of mass production with high photo-stability and at low cost. Thus, the objective of the present research is to analyze the growth process of micro crystal silicon based thin films, the crystal being a high quality silicon crystal based material, and develop technology to manufacture high-quality micro crystal silicon thin films based on the findings therefrom. It was found that, when silicon source is available in cathode, pure hydrogen plasma forms micro crystal silicon films by using the plasma as a result of the chemical transportation effect from the silicon source. It was revealed that the crystal formation due to hydrogen plasma exposure is performed substantially by the crystals forming the films due to the chemical transportation effect, rather than crystallization in the vicinity of the surface. The crystal formation under this experiment was concluded that the formation takes place during film growth accompanied by diffusion of film forming precursors on the surface on which the film grows. According to the result obtained so far, the most important issue in the future is particularly the control of crystal growing azimuth by reducing the initially formed amorphous layer by controlling the stress in the initial phase for film formation, and by controlling the film forming precursors. (NEDO)

  11. On the Crystallization of Compacted and Chunky Graphite from Liquid Multicomponent Iron-Carbon-Silicon-Based Melts

    Science.gov (United States)

    Stefanescu, D. M.; Huff, R.; Alonso, G.; Larrañaga, P.; De la Fuente, E.; Suarez, R.

    2016-08-01

    Extensive SEM work was carried out on deep-etched specimens to reveal the evolution of compacted and chunky graphite in magnesium-modified multicomponent Fe-C-Si alloys during early solidification and at room temperature. The findings of this research were then integrated in the current body of knowledge to produce an understanding of the crystallization of compacted and chunky graphite. It was confirmed that growth from the liquid for both compacted and chunky graphite occurs radially from a nucleus, as foliated crystals and dendrites. The basic building blocks of the graphite aggregates are hexagonal faceted graphite platelets with nanometer height and micrometer width. Thickening of the platelets occurs through growth of additional graphene layers nucleated at the ledges of the graphite prism. Additional thickening resulting in complete joining of the platelets may occur from the recrystallization of the amorphous carbon that has diffused from the liquid through the austenite, once the graphite aggregate is enveloped in austenite. With increasing magnesium levels, the foliated graphite platelets progressively aggregate along the c-axis forming clusters. The clusters that have random orientation, eventually produce blocky graphite, as the spaces between the parallel platelets disappear. This is typical for compacted graphite irons and tadpole graphite. The chunky graphite aggregates investigated are conical sectors of graphite platelets stacked along the c-axis. The foliated dendrites that originally develop radially from a common nucleus may aggregate along the c-axis forming blocky graphite that sometimes exhibits helical growth. The large number of defects (cavities) observed in all graphite aggregates supports the mechanism of graphite growth as foliated crystals and dendrites.

  12. The Silicon Environment in Silica Polymorphs, Aluminosilicate Crystals and Melts: An In Situ High Temperature XAS Study

    International Nuclear Information System (INIS)

    Cormier, L.; Neuville, D. R.; Roux, J.; Ligny, D. de; Henderson, G. S.; Flank, A.-M.; Lagarde, P.

    2007-01-01

    High temperature X-ray absorption spectroscopy at the Si K-edge has been used to obtain in situ information on SiO2 phase transitions upon heating. Important modifications are observed for the XANES spectra of the high temperature polymorphs, in relation to disordering of the SiO4 tetrahedra beyond the short-range correlations. This paper also presents the XANES spectra of anorthite (CaAl2Si2O8) from room temperature up to the melt (1900 K). This study shows the possibilities for determining the Si environment in crystals and glasses up to the liquid state using in situ XANES measurements

  13. Crystallization behavior of polyethylene on silicon wafers in solution casting processes traced by time-resolved measurements of synchrotron grazing-incidence small-angle and wide-angle X-ray scattering

    International Nuclear Information System (INIS)

    Sasaki, S; Masunaga, H; Takata, M; Itou, K; Tashiro, K; Okuda, H; Takahara, A

    2009-01-01

    Crystallization behavior of polyethylene (PE) on silicon wafers in solution casting processes has been successfully traced by time-resolved grazing-incidence small-angle and wide-angle X-ray scattering (GISWAXS) measurements utilizing synchrotron radiation. A p-xylene solution of PE kept at ca. 343 K was dropped on a silicon wafer at ca. 298 K. While the p-xylene evaporated naturally from the dropped solution sample, PE chains crystallized to be a thin film. Raman spectral measurements were performed simultaneously with the GISWAXS measurements to evaluate quantitatively the p-xylene the dropped solution contained. Grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns indicated nucleation and crystal growth in the dropped solution and the following as-cast film. GIWAXS and Raman spectral data revealed that crystallization of PE was enhanced after complete evaporation of the p-xylene from the dropped solution. The [110] and [200] directions of the orthorhombic PE crystal became relatively parallel to the wafer surface with time, which implied that the flat-on lamellae with respect to the wafer surface were mainly formed in the as-cast film. On the other hand, grazing-incidence small-angle X-ray scattering (GISAXS) patterns implied formation of isolated lamellae in the dropped solution. The lamellae and amorphous might alternatively be stacked in the preferred direction perpendicular to the wafer surface. The synchrotron GISWAXS experimental method could be applied for kinetic study on hierarchical structure of polymer thin films.

  14. Direct growth of large grain polycrystalline silicon films on aluminum-induced crystallization seed layer using hot-wire chemical vapor deposition

    International Nuclear Information System (INIS)

    Wu, Bing-Rui; Lo, Shih-Yung; Wuu, Dong-Sing; Ou, Sin-Liang; Mao, Hsin-Yuan; Wang, Jui-Hao; Horng, Ray-Hua

    2012-01-01

    Large grain polycrystalline silicon (poly-Si) films on glass substrates have been deposited on an aluminum-induced crystallization (AIC) seed layer using hot-wire chemical vapor deposition (HWCVD). A poly-Si seed layer was first formed by the AIC process and a thicker poly-Si film was subsequently deposited upon the seed layer using HWCVD. The effects of AIC annealing parameters on the structural and electrical properties of the poly-Si seed layers were characterized by Raman scattering spectroscopy, field-emission scanning electron microscopy, and Hall measurements. It was found that the crystallinity of seed layer was enhanced with increasing the annealing duration and temperature. The poly-Si seed layer formed at optimum annealing parameters can reach a grain size of 700 nm, hole concentration of 3.5 × 10 18 cm −3 , and Hall mobility of 22 cm 2 /Vs. After forming the seed layer, poly-Si films with good crystalline quality and high growth rate (> 1 nm/s) can be obtained using HWCVD. These results indicated that the HWCVD-deposited poly-Si film on an AIC seed layer could be a promising candidate for thin-film Si photovoltaic applications. - Highlights: ►Poly-Si seed layers are formed by aluminum-induced crystallization (AIC) process. ►Poly-Si on AIC seed layers are prepared by hot-wire chemical vapor deposition. ►AIC process parameters affect structural properties of poly-Si films. ►Increasing the annealing duration and temperature increases the film crystallinity.

  15. Near-Infrared and Optical Beam Steering and Frequency Splitting in Air-Holes-in-Silicon Inverse Photonic Crystals

    Science.gov (United States)

    2017-01-01

    We present the design of a dielectric inverse photonic crystal structure that couples line-defect waveguide propagating modes into highly directional beams of controllable directionality. The structure utilizes a triangular lattice made of air holes drilled in an infinitely thick Si slab, and it is designed for operation in the near-infrared and optical regime. The structure operation is based on the excitation and manipulation of dark dielectric surface states, in particular on the tailoring of the dark states’ coupling to outgoing radiation. This coupling is achieved with the use of properly designed external corrugations. The structure adapts and matches modes that travel through the photonic crystal and the free space. Moreover it facilitates the steering of the outgoing waves, is found to generate well-defined, spatially and spectrally isolated beams, and may serve as a frequency splitting component designed for operation in the near-infrared regime and in particular the telecom optical wavelength band. The design complies with the state-of-the-art Si nanofabrication technology and can be directly scaled for operation in the optical regime. PMID:29541653

  16. Effect of nanodimensional polyethylenimine layer on surface potential barriers of hybrid structures based on silicon single crystal

    Science.gov (United States)

    Malyar, Ivan V.; Gorin, Dmitry A.; Stetsyura, Svetlana V.

    2013-01-01

    In this report we present the analysis of I-V curves for MIS-structures like silicon substrate / nanodimensional polyelectrolyte layer / metal probe (contact) which is promising for biosensors, microfluidic chips, different devices of molecular electronics, such as OLEDs, solar cells, where polyelectrolyte layers can be used to modify semiconductor surface. The research is directed to investigate the contact phenomena which influence the resulting signal of devices mentioned above. The comparison of I-V characteristics of such structures measured by scanning tunnel microscopy (contactless technique) and using contact areas deposited by thermal evaporation onto the organic layer (the contact one) was carried out. The photoassisted I-V measurements and complex analysis based on Simmons and Schottky models allow one to extract the potential barriers and to observe the changes of charge transport in MIS-structures under illumination and after polyelectrolyte adsorption. The direct correlation between the thickness of the deposited polyelectrolyte layer and both equilibrium tunnel barrier and Schottky barrier height was observed for hybrid structures with polyethylenimine. The possibility of control over the I-V curves of hybrid structure and the height of the potential barriers (for different charge transports) by illumination was confirmed. Based on experimental data and complex analysis the band diagrams were plotted which illustrate the changes of potential barriers for MIS-structures due to the polyelectrolyte adsorption and under the illumination.

  17. A simplified boron diffusion for preparing the silicon single crystal p-n junction as an educational device

    Energy Technology Data Exchange (ETDEWEB)

    Shiota, Koki, E-mail: a14510@sr.kagawa-nct.ac.jp; Kai, Kazuho; Nagaoka, Shiro, E-mail: nagaoka@es.kagawa-nct.ac.jp [National Institute of Technology, Kagawa College, Kagawa, Mitoyo, Takuma, Koda 551 (Japan); Tsuji, Takuto [National Institute of Technology, Suzuka College, Mie, Suzuka, Shiroko (Japan); Wakahara, Akihiro [Toyohashi University of Technology, Aichi, Toyohashi, Tenpaku, Hibarigaoka 1-1 (Japan); Rusop, Mohamad [University Technology Mara, Selangor, Shah Alam, 40450 (Malaysia)

    2016-07-06

    The educational method which is including designing, making, and evaluating actual semiconductor devices with learning the theory is one of the best way to obtain the fundamental understanding of the device physics and to cultivate the ability to make unique ideas using the knowledge in the semiconductor device. In this paper, the simplified Boron thermal diffusion process using Sol-Gel material under normal air environment was proposed based on simple hypothesis and the feasibility of the reproducibility and reliability were investigated to simplify the diffusion process for making the educational devices, such as p-n junction, bipolar and pMOS devices. As the result, this method was successfully achieved making p+ region on the surface of the n-type silicon substrates with good reproducibility. And good rectification property of the p-n junctions was obtained successfully. This result indicates that there is a possibility to apply on the process making pMOS or bipolar transistors. It suggests that there is a variety of the possibility of the applications in the educational field to foster an imagination of new devices.

  18. Design of an elliptic spot illumination system in LED-based color filter-liquid-crystal-on-silicon pico projectors for mobile embedded projection.

    Science.gov (United States)

    Chen, Enguo; Yu, Feihong

    2012-06-01

    We present an elliptic spot illumination system for a color filter-liquid-crystal-on-silicon (CF-LCoS) pico projector employing a specifically designed free-form lens and a cylindrical lens to improve on previous designs in terms of optical efficiency while yielding an ultracompact and low-cost optical architecture. The detailed design description of the optical system is thoroughly investigated. Simulation results coincide well with the theoretical calculation. The single 1  mm×1  mm LED chip-powered optical engine, which employs a CF-LCoS panel with a diagonal of 0.28 in and an aspect ratio of 4:3, has an estimated output efficiency over 9.8% (11.8 lm@1 W) and an ANSI 9-point uniformity over 88.5%, with the ultrasmall volume 24  mm×19  mm×7  mm. Compared to the circular spot-illuminated projection system, a total increment of about 23% of system efficiency is available with this improved optical engine. It is believed that there would be a huge market potential to commercialize our design.

  19. Photonic crystal ring resonator-based four-channel dense wavelength division multiplexing demultiplexer on silicon on insulator platform: design and analysis

    Science.gov (United States)

    Sreenivasulu, Tupakula; Bhowmick, Kaustav; Samad, Shafeek A.; Yadunath, Thamerassery Illam R.; Badrinarayana, Tarimala; Hegde, Gopalkrishna; Srinivas, Talabattula

    2018-04-01

    A micro/nanofabrication feasible compact photonic crystal (PC) ring-resonator-based channel drop filter has been designed and analyzed for operation in C and L bands of communication window. The four-channel demultiplexer consists of ring resonators of holes in two-dimensional PC slab. The proposed assembly design of dense wavelength division multiplexing setup is shown to achieve optimal quality factor, without altering the lattice parameters or resonator size or inclusion of scattering holes. Transmission characteristics are analyzed using the three-dimensional finite-difference time-domain simulation approach. The radiation loss of the ring resonator was minimized by forced cancelation of radiation fields by fine-tuning the air holes inside the ring resonator. An average cross talk of -34 dB has been achieved between the adjacent channels maintaining an average quality factor of 5000. Demultiplexing is achieved by engineering only the air holes inside the ring, which makes it a simple and tolerant design from the fabrication perspective. Also, the device footprint of 500 μm2 on silicon on insulator platform makes it easy to fabricate the device using e-beam lithography technique.

  20. Theoretical proposal of a low-loss wide-bandwidth silicon photonic crystal fiber for supporting 30 orbital angular momentum modes.

    Directory of Open Access Journals (Sweden)

    Xun Xu

    Full Text Available We propose a novel four-ring hollow-core silicon photonic crystal fiber (PCF, and we systematically and theoretically investigate the properties of their vector modes. Our PCF can stably support 30 OAM states from the wavelength of 1.5 μm to 2.4 μm, with a large effective refractive index separation of above 1×10-4. The confinement loss is less than 1×10-9 dB/m at the wavelength of 1.55 μm, and the average confinement loss is less than 1×10-8 dB/m from the wavelength of 1.2 μm to 2.4 μm. Moreover, the curve of the dispersion tends to flatten as the wavelength increases. In addition, we comparably investigate PCFs with different hole spacing. This kind of fiber structure will be a potential candidate for high-capacity optical fiber communications and OAM sensing applications using fibers.

  1. Effect of substrate bias voltage on tensile properties of single crystal silicon microstructure fully coated with plasma CVD diamond-like carbon film

    Science.gov (United States)

    Zhang, Wenlei; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

    2018-06-01

    Tensile strength and strength distribution in a microstructure of single crystal silicon (SCS) were improved significantly by coating the surface with a diamond-like carbon (DLC) film. To explore the influence of coating parameters and the mechanism of film fracture, SCS microstructure surfaces (120 × 4 × 5 μm3) were fully coated by plasma enhanced chemical vapor deposition (PECVD) of a DLC at five different bias voltages. After the depositions, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal desorption spectrometry (TDS), surface profilometry, atomic force microscope (AFM) measurement, and nanoindentation methods were used to study the chemical and mechanical properties of the deposited DLC films. Tensile test indicated that the average strength of coated samples was 13.2-29.6% higher than that of the SCS sample, and samples fabricated with a -400 V bias voltage were strongest. The fracture toughness of the DLC film was the dominant factor in the observed tensile strength. Deviations in strength were reduced with increasingly negative bias voltage. The effect of residual stress on the tensile properties is discussed in detail.

  2. Shape of growing crystals of primary phases in autectic alloys of Fe - Fe2B and Ni - Ni3B systems

    International Nuclear Information System (INIS)

    Tavadze, F.N.; Garibashvili, V.I.; Nakaidze, Sh.G.

    1983-01-01

    Shapes of Fe 2 B and Ni 3 B crystal growth in eutectic Fe-B and Ni-B system alloys are considered. Iron hemiboride primary crystals take the form of a plane-face phase boundary and inherit a tetragonal prismatic lattice. After the crystal attains the critical size the dendritic branching occurs resulting in formation of a typical sceleton dendrite. Comparison of data obtained with entropy of melting for Fe 2 B and Ni 3 B borides shows that FeB crystals during the growth should take the spherical form. It is stated that the shape of growing crystals in Fe-Fe 2 B and Ni-Ni 2 B eutectic colonies is determined by the shape of borides

  3. Solid phase epitaxy on N-type polysilicon films formed by aluminium induced crystallization of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Tuezuen, O., E-mail: Ozge.Tuzun@iness.c-strasbourg.f [InESS, UMR 7163 CNRS-UdS, 23 rue du Loess, F-67037 Strasbourg Cedex 2 (France); Slaoui, A.; Roques, S.; Focsa, A. [InESS, UMR 7163 CNRS-UdS, 23 rue du Loess, F-67037 Strasbourg Cedex 2 (France); Jomard, F.; Ballutaud, D. [GEMaC-UMR 8635 CNRS, 1 place Aristide Briand, F-92195 Meudon (France)

    2009-10-01

    In this work, undoped amorphous silicon layers were deposited on n-type AIC seed films and then annealed at different temperatures for epitaxial growth. The epitaxy was carried out using halogen lamps (rapid thermal process or RTP) or a tube conventional furnace (CTP). We investigated the morphology of the resulting 2 {mu}m thick epi-layers by means of optical microscopy. An average grain size of about 40 {mu}m is formed after 90 s annealing at 1000 {sup o}C in RTP. The stress and degree of crystallinity of the epi-layers were studied by micro-Raman Spectroscopy and UV-visible spectrometer as a function of annealing time. The presence of compressive stress is observed from the peak position which shifts from 520.0 cm{sup -1} to 521.0 cm{sup -1} and 522.3 cm{sup -1} after CTP annealing for 10 min and 90 min, respectively. It is shown that the full width at half maximum (FWHM) varies from 9.8 cm{sup -1} to 15.6 cm{sup -1}, and the magnitude of stress is changing from 325 MPa to 650 MPa. Finally, the highest crystallinity is achieved after annealing at 1000 {sup o}C for 90 min in a tube furnace exhibiting a crystalline fraction of 81.5%. X-ray diffraction technique was used to determine the preferential orientation of the poly-Si thin films formed by SPE technique on n{sup +} type AIC layer. The preferential orientation is <100> for all annealing times at 1000 {sup o}C.

  4. Simulation of primary processes for laser-induced plasma by short laser pulses in KDP crystal

    International Nuclear Information System (INIS)

    Gayet, R.; Jequier, S.; Bachau, H.; Rodriguez, V.; Duchateau, G.; Dyan, A.; Mathis, H.

    2006-01-01

    Complete test of publication follows. A theoretical approach designed for the description of local micro-plasma formation induced by short laser pulses in KH 2 PO 4 (KDP) crystal is addressed. Indeed, when such a crystal is illuminated by short pulses, the early stage of photo-production, enhanced by local defects, leads to a subsequent strong electronic absorption revealing a transient metallic-like behavior. The lattice then is rapidly heated up by electron-phonon coupling at temperature as high as 10000 K. This results in the local formation of a micro-plasma whose initial electronic energy distribution, which can be used in Particle-In-Cell codes, may be predicted by the present approach. The latter includes both, electron promotion from the valence band to the conduction band, and the subsequent interaction with phonons and photons. The electron promotion is described by a theoretical method based on Coulomb-Volkov (CV) wave functions whereas the electron diffusion in the conduction band is described by the standard Boltzmann's formalism. Although results about diffusion are shown, the present work focuses on the photo-production step. Hence, an extension of a previous theory, which has been developed essentially to describe ionization of atoms or molecules by intense femtosecond laser pulses, in under way. The first theory gives reliable predictions whenever both, (i) the photon energy is greater than the ionization potential, and (ii) perturbation conditions prevail. The restriction (i) prevents from intermediate state contribution to the ionization mechanism. The CV approach has been improved by introducing these states in the initial wave function, thus leading to an excellent agreement with predictions based on a full numerical solution to the time-dependent Schroedinger equation. Further, keeping the restriction (i), one can discard the condition (ii) by introducing a time-dependent initial state population in a CV approach. Since defects induce

  5. Advances in silicon nanophotonics

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Pu, Minhao

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

  6. Metal induced crystallization of amorphous silicon thin films studied by x-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

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

    2013-01-01

    The role of thin metallic layer (Chromium or Nickel) in the crystallization of a-Si film has been studied using X-ray absorption fine structure spectroscopy (XAFS). The films were grown at different substrate temperatures in two different geometrical structures : (a) a 200 nm metal layer (Cr or Ni) was deposited on fused silica (FS) followed by 400 nm of a-Si and (b) the 400 nm a-Si layer was deposited on FS followed by 200 nm of metal layer. XAFS measurements at Cr K-edge and Ni K-edge were done at BM08 – GILDA beamline of the European Synchrotron Research Facility (ESRF, Grenoble, F) in fluorescence mode. To understand the evolution of the local structure of Cr/Ni diffusing from bottom to top and from top to bottom, total reflection and higher incidence angles were employed. The relative content of metal, metal oxide and metal silicides compounds on the upper surface and/or in the bulk of different films has been evaluated as a function of thermal treatment.

  7. Liquidus temperature in the spinel primary phase field: A comparison between optical and crystal fraction methods

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Brian J.; Hrma, Pavel; Crum, Jarrod V.; Vienna, John D.; Schweiger, Michael J.; Rodriguez, Carmen P.; Peterson, Jacob A.

    2018-03-01

    Liquidus temperature (TL) was measured for simulated high-level waste borosilicate glasses covering a Hanford composition region, using an optical method and a crystal-fraction extrapolation method with X-ray diffraction data from isothermal heat treatments. The 38 glasses encompassed a one-component-at-a-time variation of a 16-component matrix. The TL values ranged from 1006°C to 1603°C. First-order polynomial models were fitted to data to obtain coefficients in terms of the effect of 1 mass% component addition on the TL: TL-increasing oxides Cr2O3 (264°C), “Others” (minor components, 163°C), oxides of noble metals (137°C), NiO (91°C), Al2O3 and Fe2O3 (~19–21°C); TL-decreasing oxides K2O (-26°C), Na2O (-41°C), and Li2O (-68°C); oxides of little effect MnO, P2O5, ZrO2, F, Bi2O3, SiO2, B2O3, and CaO (9 to -12°C). Also presented are temperatures (T1%) at which glasses contain 1 vol% of spinel as these values are considered relevant to the Hanford Tank Waste Treatment and Immobilization Plant. The measured and estimated values are compared and contrasted and the effect of TL and T1% on glass formulation is discussed.

  8. Fiscal 1974 Sunshine Project result report. R and D on photovoltaic power generation system (R and D on Si ribbon crystal horizontal pulling method); 1974 nendo taiyoko hatsuden system seika hokokusho. Silicon yokohiki ribbon kessho no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1975-05-01

    The ribbon crystal horizontal pulling process first supplies Si melt from a continuous Si material supply equipment to a pulling bath which is formed by a quartz crucible and heater. Supplied melt is heated by the pulling bath heater to keep its molten condition. The pulling bath is piled up to the top rim of the quartz crucible by supplied melt, forming the liquid surface of the pulling bath. A plane crystal seed is contacted with melt nearly horizontally. A crystal growth layer is formed at the solid-liquid interface of the contact part of the seed by controlling a heat control equipment and bath heating power. Non-dendrite growth is better in crystal quality than the others. Among non-dendrite growth methods, a horizontal pulling method is more excellent in fast pulling of wider ribbon crystals than a vertical one. Among horizontal pulling methods, Toyo Silicon Co.' method discharges heat into gas phase by using free surface including the vicinity of the seed as cooling surface, while Bleil method uses a solid heat sink for heat release, resulting in slower crystal growth. (NEDO)

  9. Silicon etch process

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  10. Primary defect transformations in high-resistivity p-type silicon irradiated with electrons at cryogenic temperatures

    CERN Document Server

    Makarenko, L F; Korshunov, F P; Murin, L I; Moll, M

    2009-01-01

    It has been revealed that self-interstitials formed under low intensity electron irradiationin high resistivity p-type silicon can be retained frozen up to room temperature. Low thermal mobility of the self-interstitials suggests that Frenkelpair sinsilicon can be stable at temperatures of about or higher than 100K. A broad DLTS peak with activation energy of 0.14–0.17eV can be identified as related to Frenkel pairs. This peak anneals out at temperatures of 120 140K. Experimental evidences are presented that be coming more mobile under forwardcurrent injection the self-interstitials change their charge state to a less positive one.

  11. Imprinted silicon-based nanophotonics

    DEFF Research Database (Denmark)

    Borel, Peter Ingo; Olsen, Brian Bilenberg; Frandsen, Lars Hagedorn

    2007-01-01

    We demonstrate and optically characterize silicon-on-insulator based nanophotonic devices fabricated by nanoimprint lithography. In our demonstration, we have realized ordinary and topology-optimized photonic crystal waveguide structures. The topology-optimized structures require lateral pattern ...

  12. Equation of liquidus curve of primary crystallization of congruently melting of Asub(m)Bsub(n) compound in regular solutions approximation

    International Nuclear Information System (INIS)

    Glazov, V.M.; Pavlova, L.M.; Moskvinova, N.A.

    1975-01-01

    A general solution was obtained for the Prigozhin and Defey equation on the basis of which a liquidus equation was derived describing the primary crystallization of Asub(m)Bsub(n)-type compounds. The Prigozhin and Defey equation described a general case of the melting process of having a narrow homogeneity region at a certain temperature T:(Asub(m)Bsub(n))sub(s) reversible m(A)sub(L) n(B)sub(L). They have obtained a differential equation for the liquids curve describing the equilibrium state between the primary Asub(m)Bsub(n) crystals and the liquid solution. The obtained equation was tested by a comparison with the experimental liquidus curves corresponding to the primary crystallization of gallium and indium sesquitellurides in Ga-Te and In-Te systems. The liquidus curves were made more precise by means of a detailed thermographic study of a series of melts located to the right and left of Ga 2 Te 3 and In 2 Te 3 compounds. Computer calculations of liquidus curves corresponding to the primary crystallization of Ga 2 Te 3 and In 2 Te 3 were carried out with the aid of the last of the above-mentioned equations. The obtained results show that the derived equations can be used in studying the nature of intermolecular reactions in systems in which congruent intermediate phases of complex composition are present

  13. New orientation formation and growth during primary recrystallization in stable single crystals of three face-centred cubic metals

    International Nuclear Information System (INIS)

    Miszczyk, M.; Paul, H.; Driver, J.H.; Maurice, C.

    2015-01-01

    Graphical abstract: For Ni, Cu and Cu-2%Al and (1 1 0)[0 0 −1] and (1 1 0)[1 −1 −2] initial orientations at the initial stages of recrystallization, the appearance of a specific number of new orientation groups of new grains has been demonstrated. The orientation relations across the recrystallization front are characterized by a high proportion of angles in the range 25–35° and 45–55° around axes mostly grouped about the 〈1 2 2〉, 〈1 1 1〉, 〈1 2 3〉 and 〈1 1 2〉 directions. A local minimum was noted for the disorientation angle densities close to 40° in all cases. For a single isolated nucleus of uniform orientation, the rotation axes are usually grouped around one of the normals of all four {1 1 1} planes but do not (or only rarely) coincide with them. The orientation of the growing new grain quickly transforms through the formation of a first generation twins. The most frequent situation occurs when the normal of the twinning face plane is situated near the rotation axis, around which the crystal lattice of the ‘primary nuclei’ rotates. Based on the anisotropy of grain growth a possible mechanism of orientation generation and grain growth by thermally activation movement of dislocation families, on {1 1 1} planes is proposed. - Abstract: The early stages of recrystallization have been systematically characterized in single crystal metals of medium and low stacking fault energy. Goss {1 1 0}〈0 0 1〉 and brass {1 1 0}〈1 1 2〉 oriented samples of Ni, Cu and Cu–2 wt.% Al alloy were deformed in a channel die to a logarithmic strain of 0.51 to develop a homogeneous structure composed of two sets of symmetrical primary microbands and then lightly annealed. Scanning electron microscopy/electron backscattered diffraction analyses demonstrate a strong relation between as-deformed orientations and the limited number of recrystallized grain orientations. The disorientation angles across the recrystallization front are mostly grouped in

  14. Process Research on Polycrystalline Silicon Material (PROPSM)

    Science.gov (United States)

    Culik, J. S.; Wrigley, C. Y.

    1985-01-01

    Results of hydrogen-passivated polycrysalline silicon solar cell research are summarized. The short-circuit current of solar cells fabricated from large-grain cast polycrystalline silicon is nearly equivalent to that of single-crystal cells, which indicates long bulk minority-carrier diffusion length. Treatments with molecular hydrogen showed no effect on large-grain cast polycrystalline silicon solar cells.

  15. Silicone metalization

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-12-09

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

  16. Periodically poled silicon

    Science.gov (United States)

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

    2010-02-01

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

  17. Nonlinear silicon photonics

    Science.gov (United States)

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

    2017-09-01

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

  18. New aspects on the contribution of primary defects in silicon due to long-time degradation of detectors operating in high fields of radiation

    International Nuclear Information System (INIS)

    Lazanu, Sorina; Lazanu, Ionel

    2006-01-01

    Full text: Silicon detectors will represent an important option for the next generation of experiments in high energy physics, for astroparticle and nuclear experiments, where the requirements to operate long time in high radiation environments will represent a major problem. After the long-time operation in high radiation fields, the bulk displacement damage produces the following effects at the device level: increase of the leakage current, decrease of the satisfactory Signal/Noise ratio, increase of the effective carrier concentration, and thus of the depletion voltage, decrease of the charge collection efficiency up to unacceptable levels. In this contribution we investigate the new perspective in understanding the fundamental phenomena in silicon and implications for the degradation of the characteristics of detectors given by the consideration of the existence of the new primary defect: fourfold coordinated defect, Si FFCD , with a lower value of the formation energy by comparison with the 'classically' known vacancies and interstitials. Predicted by Goedecker and co-workers, its characteristics were indirectly determined by Lazanu and Lazanu. The correlation between the rate of generation of primary defects, material composition and observable effects is investigated considering different growth technologies and resistivities (up to tens of kΩcm) as time and fluence dependencies. This allows to estimate the expected behaviour of the materials and detectors in concrete environments at the next generations of high energy physics experiments as SLHC or VLHC for example. This new defect could represent the elementary block for new extended defects and in principle it could generate local amorphization of the semiconductor. Its existence and characteristics in other semiconductors is also investigated. (author)

  19. Report on 1979 result of Sunshine Project. R and D on solar power generation system (R and D on particle non-accelerated growth type silicon thin film crystal); 1979 nendo taiyoko hatsuden system no kenkyu kaihatsu seika hokokusho. Ryushi hikasoku seichogata silicon usumaku kessho no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-03-01

    The R and D was intended to establish the manufacturing technology of a particle non-accelerated growth type silicon thin film crystal, for the purpose of developing a technology for enabling the production of a solar power generation system, whose price is practically 1/100 compared with that of building the system with the current technology, and the R and D was also intended to build the system using such silicon material. While a simple purification method was examined for a low purity metallurgical-grade silicon, a solar-grade silicon (SOG) was developed as the new material this year, with a solar cell experimentally manufactured having a structure directly joined to the substrate material and with evaluation carried out on the characteristic of such solar cell. The application of 'gettering' was tried which was for removing harmful impurities from the substrate obtained from such material, bringing an outlook of manufacturing a solar cell with a conversion efficiency of 10%. Concerning the SOG-Si, the efficiency of 13% or higher was attained through the improvement of the manufacturing process. This was the value comparable to the case of using a conventional high purity monocrystal wafer. Further, the application of an ion implantation method was studied for the purpose of getting a low cost. (NEDO)

  20. CCDC 939502: Experimental Crystal Structure Determination : catena-[hexadecakis(N,N-Dicyclohexyl-N-ethyl-N-methylammonium) icosahectakis(mu2-oxo)-hexapentaconta(germanium-silicon)

    KAUST Repository

    Yu, Zheng-Bao; Han, Yu; Zhao, Lan; Huang, Shiliang; Zheng, Qi-Yu; Lin, Shuangzheng; Có rdova, Armando; Zou, Xiaodong; Sun, Junliang

    2013-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from

  1. Thermal resistor on the base of silicon and some polymer semiconductors

    International Nuclear Information System (INIS)

    Marupov, R.; Kasimov, Sh.T.; Achilov, T.Kh.; Karimov, Kh.S.; Akhmedov, Kh.M.

    1995-01-01

    The purpose of present work is investigation electrical properties ofthermal resistors which was made from second cast poly-crystal silicon,poly-carbazole, and compositions of poly-crystal silicon and poly-carbazole

  2. Surface Effects in Segmented Silicon Sensors

    OpenAIRE

    Kopsalis, Ioannis

    2017-01-01

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

  3. Morphology transition of the primary silicon particles in a hypereutectic A390 alloy in high pressure die casting.

    Science.gov (United States)

    Wang, J; Guo, Z; Song, J L; Hu, W X; Li, J C; Xiong, S M

    2017-11-03

    The microstructure of a high-pressure die-cast hypereutectic A390 alloy, including PSPs, pores, α-Al grains and Cu-rich phases, was characterized using synchrotron X-ray tomography, together with SEM, TEM and EBSD. The Cu-rich phases exhibited a net morphology and distributed at the boundaries of the α-Al grains, which in turn surrounded the PSPs. Statistical analysis of the reconstructed 1000 PSPs showed that both equivalent diameter and shape factor of the PSPs exhibited a unimodal distribution with peaks corresponding to 25 μm and 0.78, respectively.) PSPs morphology with multiple twinning were observed and morphological or growth transition of the PSPs from regular octahedral shape (with a shape factor of 0.85 was mainly caused by the constraint of the Cu-rich phases. In particular, the presence of the Cu-rich phases restricted the growth of the α-Al grains, inducing stress on the internal silicon particles, which caused multiple twinning occurrence with higher growth potential and consequently led to growth transitions of the PSPs.

  4. Silicon microfabricated beam expander

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  5. Silicon microfabricated beam expander

    Science.gov (United States)

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

    2015-03-01

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

  6. Silicon microfabricated beam expander

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-30

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

  7. Role of the bond defect for structural transformations between crystalline and amorphous silicon: A molecular-dynamics study

    International Nuclear Information System (INIS)

    Stock, D. M.; Weber, B.; Gaertner, K.

    2000-01-01

    The relation between the bond defect, which is a topological defect, and structural transformations between crystalline and amorphous silicon, is studied by molecular-dynamics simulations. The investigation of 1-keV boron implantation into crystalline silicon proves that the bond defect can also be generated directly by collisional-induced bond switching in addition to its formation by incomplete recombination of primary defects. This supports the assumption that the bond defect may play an important role in the amorphization process of silicon by light ions. The analysis of the interface between (001) silicon and amorphous silicon shows that there are two typical defect configurations at the interface which result from two different orientations of the bond defect with respect to the interface. Thus the bond defect appears to be a characteristic structural feature of the interface. Moreover, annealing results indicate that the bond defect acts as a growth site for interface-mediated crystallization

  8. Back contact to film silicon on metal for photovoltaic cells

    Science.gov (United States)

    Branz, Howard M.; Teplin, Charles; Stradins, Pauls

    2013-06-18

    A crystal oriented metal back contact for solar cells is disclosed herein. In one embodiment, a photovoltaic device and methods for making the photovoltaic device are disclosed. The photovoltaic device includes a metal substrate with a crystalline orientation and a heteroepitaxial crystal silicon layer having the same crystal orientation of the metal substrate. A heteroepitaxial buffer layer having the crystal orientation of the metal substrate is positioned between the substrate and the crystal silicon layer to reduce diffusion of metal from the metal foil into the crystal silicon layer and provide chemical compatibility with the heteroepitaxial crystal silicon layer. Additionally, the buffer layer includes one or more electrically conductive pathways to electrically couple the crystal silicon layer and the metal substrate.

  9. Process for making silicon

    Science.gov (United States)

    Levin, Harry (Inventor)

    1987-01-01

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

  10. Achievement report for fiscal 1997 on development of practical application technology for photovoltaic power generation systems. Development of technologies to manufacture thin film solar cells (development of technologies to manufacture silicon crystal based high-quality materials and substrates / survey and research on analysis of practical application); 1997 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu seika hokokusho. Usumaku taiyo denchi no seizo gijutsu kaihatsu (zairyo kiban seizo gijutsu kaihatsu / silicon kesshokei kohinshitsu zairyo kiban no seizo gijutsu kaihatsu (jitsuyoka kaiseki ni kansuru chosa kenkyu))

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    As a plan to develop technologies to manufacture materials and substrates for thin film solar cells, it is intended to reduce defect density, enhance film forming speed, largely improve the photo-electric conversion efficiency and increase manufacturing productivity. These goals will be realized by establishing methods to control defect density, crystal particle diameters and crystallization rate in silicon crystal systems. A technology to form micro-crystal silicon-based thin films will be developed, that have superior photo-stability, and are capable of realizing low cost and mass production. Discussions will be given on a high-density plasma control technology, a fundamental property evaluation technology for micro crystal silicon thin films, and a device design simulation technology. A technology will be developed to form amorphous silicon layer on a stainless steel substrate by using the plasma CVD process. At the same time, discussions will be given on optical annealing and thermal annealing as reformation methods. Fiscal 1997 has surveyed component technologies to identify and analyze quickly and accurately the technical trends inside and outside the country, and to mass produce thin film solar cells. The Material and Substrate System Technology Subcommittee (silicon crystals) was held to deliberate the four-year development program and its progress. (NEDO)

  11. Harmonic and Anharmonic Properties of Diamond Structure Crystals with Application to the Calculation of the Thermal Expansion of Silicon. Ph.D. Thesis. Final Report

    Science.gov (United States)

    Wanser, K. H.

    1981-01-01

    Silicon has interesting harmonic and anharmonic properties such as the low lying transverse acoustic modes at the X and L points of the Brillouin zone, negative Gruneisen parameters, negative thermal expansion and anomalous acoustic attenuation. In an attempt to understand these properties, a lattice dynamical model employing long range, nonlocal, dipole-dipole interactions was developed. Analytic expression for the Gruneisen parameters of several modes are presented. These expressions explain how the negative Gruneisen parameters arise. This model is applied to the calculation of the thermal expansion of silicon from 5K to 1700K. The thermoelastic contribution to the acoustic attenuation of silicon is computed from 1 to 300 K. Strong attenuation anomalies associated with negative thermal expansion are found in the vicinity of 17K and 125K.

  12. Characterization of 1.2×1.2 mm2 silicon photomultipliers with Ce:LYSO, Ce:GAGG, and Pr:LuAG scintillation crystals as detector modules for positron emission tomography

    Science.gov (United States)

    Omidvari, N.; Sharma, R.; Ganka, T. R.; Schneider, F. R.; Paul, S.; Ziegler, S. I.

    2017-04-01

    The design of a positron emission tomography (PET) scanner is specially challenging since it should not compromise high spatial resolution, high sensitivity, high count-rate capability, and good energy and time resolution. The geometrical design of the system alongside the characteristics of the individual PET detector modules contributes to the overall performance of the scanner. The detector performance is mainly influenced by the characteristics of the photo-detector and the scintillation crystal. Although silicon photomultipliers (SiPMs) have already proven to be promising photo-detectors for PET, their performance is highly influenced by micro-cell structure and production technology. Therefore, five types of SiPMs produced by KETEK with an active area size of 1.2 × 1.2 mm2 were characterized in this study. The SiPMs differed in the production technology and had micro-cell sizes of 25, 50, 75, and 100 μm. Performance of the SiPMs was evaluated in terms of their breakdown voltage, temperature sensitivity, dark count rate, and correlated noise probability. Subsequently, energy resolution and coincidence time resolution (CTR) of the SiPMs were measured with five types of crystals, including two Ce:LYSO, two Ce:GAGG, and one Pr:LuAG. Two crystals with a geometry of 1.5 × 1.5 × 6 mm3 were available from each type. The best CTR achieved was ~ 240 ps, which was obtained with the Ce:LYSO crystals coupled to the 50 μm SiPM produced with the trench technology. The best energy resolution for the 511 keV photo-peak was ~ 11% and was obtained with the same SiPM coupled to the Ce:GAGG crystals.

  13. Characterization of 1.2×1.2 mm2 silicon photomultipliers with Ce:LYSO, Ce:GAGG, and Pr:LuAG scintillation crystals as detector modules for positron emission tomography

    International Nuclear Information System (INIS)

    Omidvari, N.; Sharma, R.; Schneider, F.R.; Ziegler, S.I.; Ganka, T.R.; Paul, S.

    2017-01-01

    The design of a positron emission tomography (PET) scanner is specially challenging since it should not compromise high spatial resolution, high sensitivity, high count-rate capability, and good energy and time resolution. The geometrical design of the system alongside the characteristics of the individual PET detector modules contributes to the overall performance of the scanner. The detector performance is mainly influenced by the characteristics of the photo-detector and the scintillation crystal. Although silicon photomultipliers (SiPMs) have already proven to be promising photo-detectors for PET, their performance is highly influenced by micro-cell structure and production technology. Therefore, five types of SiPMs produced by KETEK with an active area size of 1.2 × 1.2 mm 2 were characterized in this study. The SiPMs differed in the production technology and had micro-cell sizes of 25, 50, 75, and 100 μm. Performance of the SiPMs was evaluated in terms of their breakdown voltage, temperature sensitivity, dark count rate, and correlated noise probability. Subsequently, energy resolution and coincidence time resolution (CTR) of the SiPMs were measured with five types of crystals, including two Ce:LYSO, two Ce:GAGG, and one Pr:LuAG. Two crystals with a geometry of 1.5 × 1.5 × 6 mm 3 were available from each type. The best CTR achieved was ∼ 240 ps, which was obtained with the Ce:LYSO crystals coupled to the 50 μm SiPM produced with the trench technology. The best energy resolution for the 511 keV photo-peak was ∼ 11% and was obtained with the same SiPM coupled to the Ce:GAGG crystals.

  14. Strained Silicon Photonics

    Directory of Open Access Journals (Sweden)

    Ralf B. Wehrspohn

    2012-05-01

    Full Text Available A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.

  15. CCDC 939502: Experimental Crystal Structure Determination : catena-[hexadecakis(N,N-Dicyclohexyl-N-ethyl-N-methylammonium) icosahectakis(mu2-oxo)-hexapentaconta(germanium-silicon)

    KAUST Repository

    Yu, Zheng-Bao

    2013-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  16. Printed Large-Area Single-Mode Photonic Crystal Bandedge Surface-Emitting Lasers on Silicon (Open Access Publisher’s Version)

    Science.gov (United States)

    2016-01-04

    TM, p) polarizations, for PCSEL-I and -II respectively. One can see that all of these bands are very flat at the edges close to Γ point, which... organised In0. 5Ga0. 5As quantum dot laser on silicon. Electron. Lett. 41, 742–744 (2005). 7. Balakrishnan, G. et al. Room-Temperature Optically Pumped

  17. The Ste locus, a component of the parasitic cry-Ste system of Drosophila melanogaster, encodes a protein that forms crystals in primary spermatocytes and mimics properties of the beta subunit of casein kinase 2

    DEFF Research Database (Denmark)

    Bozzetti, M P; Massari, S; Finelli, P

    1995-01-01

    Males of Drosophila melanogaster lacking the Y chromosome-linked crystal locus show multiple meiotic alterations including chromosome disorganization and prominent crystal formation in primary spermatocytes. These alterations are due to the derepression of the X chromosome-linked Stellate sequenc...

  18. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-30

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

  19. Silicon on insulator self-aligned transistors

    Science.gov (United States)

    McCarthy, Anthony M.

    2003-11-18

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

  20. Silicon detectors

    International Nuclear Information System (INIS)

    Klanner, R.

    1984-08-01

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

  1. Solution of kinetic equation by means of the moments method for phonon thermoconductivity and effect of isotopic disorder on it in the case of germanium and silicon crystals at T = 300 K

    CERN Document Server

    Zhernov, A P

    2001-01-01

    The problem on solving the kinetic equation through the moments method for the dielectric and semiconductor thermal conductivity is discussed. The evaluations of the isotopic disorder effect on the germanium crystals heat resistance in the multimoment approximation are obtained on the basis of the microscopic models. The contributions of the acoustic and optical phonons to the thermal conductivity are accounted for. The DELTA W surplus heat resistance in comparison with highly-enriched samples was determined for the natural composition samples. Good agreement between the theory and experiment for DELTA W is observed in the case of germanium. The theoretical value in the case of silicon is essentially lower as compared to the DELTA W experimental value

  2. Selfsupported epitaxial silicon films

    International Nuclear Information System (INIS)

    Lazarovici, D.; Popescu, A.

    1975-01-01

    The methods of removing the p or p + support of an n-type epitaxial silicon layer using electrochemical etching are described. So far, only n + -n junctions have been processed. The condition of anodic dissolution for some values of the support and layer resistivity are given. By this method very thin single crystal selfsupported targets of convenient areas can be obtained for channeling - blocking experiments

  3. Crystal structure of (110) oriented La0.7Sr0.3MnO3 grown on (001) silicon

    International Nuclear Information System (INIS)

    Sinha, Umesh Kumar; Sahoo, Antarjami; Padhan, Prahallad

    2016-01-01

    The mixed valance perovskite manganites have attracted a considerable attention due to their colossal magnetoresistance behavior. In particular, La 0.7 Sr 0.3 MnO 3 (LSMO) show half metallicity and possess Curie temperature (T C ) above room temperature, which makes this material an attractive candidate for spintronic device application. Thin films of LSMO were grown on (001) oriented Silicon (Si) using sputtering technique

  4. Muonium states in silicon carbide

    International Nuclear Information System (INIS)

    Patterson, B.D.; Baumeler, H.; Keller, H.; Kiefl, R.F.; Kuendig, W.; Odermatt, W.; Schneider, J.W.; Estle, T.L.; Spencer, D.P.; Savic, I.M.

    1986-01-01

    Implanted muons in samples of silicon carbide have been observed to form paramagnetic muonium centers (μ + e - ). Muonium precession signals in low applied magnetic fields have been observed at 22 K in a granular sample of cubic β-SiC, however it was not possible to determine the hyperfine frequency. In a signal crystal sample of hexagonal 6H-SiC, three apparently isotropic muonium states were observed at 20 K and two at 300 K, all with hyperfine frequencies intermediate between those of the isotropic muonium centers in diamond and silicon. No evidence was seen of an anisotropic muonium state analogous to the Mu * state in diamond and silicon. (orig.)

  5. On the determining role of network structure titania in silicone against bacterial colonization: Mechanism and disruption of biofilm

    International Nuclear Information System (INIS)

    Depan, D.; Misra, R.D.K.

    2014-01-01

    Silicone-based biomedical devices are prone to microbial adhesion, which is the primary cause of concern in the functioning of the artificial device. Silicone exhibiting long-term and effective antibacterial ability is highly desirable to prevent implant related infections. In this regard, nanophase titania was incorporated in silicone as an integral part of the silicone network structure through cross-link mechanism, with the objective to reduce bacterial adhesion to a minimum. The bacterial adhesion was studied using crystal violet assay, while the mechanism of inhibition of biofilm formation was studied via electron microscopy. The incorporation of nanophase titania in silicone dramatically reduced the viability of Staphylococcus aureus (S. aureus) and the capability to adhere on the surface of hybrid silicone by ∼ 93% in relation to stand alone silicone. The conclusion of dramatic reduction in the viability of S. aureus is corroborated by different experimental approaches including biofilm inhibition assay, zone of inhibition, and through a novel experiment that involved incubation of biofilm with titania nanoparticles. It is proposed that the mechanism of disruption of bacterial film in the presence of titania involves puncturing of the bacterial cell membrane. - Highlights: • Network structure titania in silicone imparts antimicrobial activity. • Ability to microbial adhesion is significantly reduced. • Antimicrobial mechanism involves rupture of biofilm

  6. Silicon wafers for integrated circuit process

    OpenAIRE

    Leroy , B.

    1986-01-01

    Silicon as a substrate material will continue to dominate the market of integrated circuits for many years. We first review how crystal pulling procedures impact the quality of silicon. We then investigate how thermal treatments affect the behaviour of oxygen and carbon, and how, as a result, the quality of silicon wafers evolves. Gettering techniques are then presented. We conclude by detailing the requirements that wafers must satisfy at the incoming inspection.

  7. Silicon Sheet Quality is Improved By Meniscus Control

    Science.gov (United States)

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

    1983-01-01

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

  8. ALICE Silicon Pixel Detector

    CERN Multimedia

    Manzari, V

    2013-01-01

    The Silicon Pixel Detector (SPD) forms the innermost two layers of the 6-layer barrel Inner Tracking System (ITS). The SPD plays a key role in the determination of the position of the primary collision and in the reconstruction of the secondary vertices from particle decays.

  9. A multiple p-n junction structure obtained from as-grown Czochralski silicon crystals by heat treatment - Application to solar cells

    Science.gov (United States)

    Chi, J. Y.; Gatos, H. C.; Mao, B. Y.

    1980-01-01

    Multiple p-n junctions have been prepared in as-grown Czochralski p-type silicon through overcompensation near the oxygen periodic concentration maxima by oxygen thermal donors generated during heat treatment at 450 C. Application of the multiple p-n-junction configuration to photovoltaic energy conversion has been investigated. A new solar-cell structure based on multiple p-n-junctions was developed. Theoretical analysis showed that a significant increase in collection efficiency over the conventional solar cells can be achieved.

  10. Continuous Czochralski growth: Silicon sheet growth development of the large area sheet task of the low cost silicon solar array project

    Science.gov (United States)

    Johnson, C. M.

    1980-12-01

    The growth of 100 kg of silicon single crystal material, ten cm in diameter or greater, and 150 kg of silicon single crystal material 15 cm or greater utilizing one common silicon container material (one crucible) is investigated. A crystal grower that is recharged with a new supply of polysilicon material while still under vacuum and at temperatures above the melting point of silicon is developed. It accepts large polysilicon charges up to 30 kg, grows large crystal ingots (to 15 cm diameter and 25 kg in weight), and holds polysilicon material for recharging (rod or lump) while, at the same time, growing crystal ingots. Special equipment is designed to recharge polysilicon rods, recharge polysilicon lumps, and handle and store large, hot silicon crystal ingots. Many continuous crystal growth runs were performed lasting as long as 109 hours and producing as many as ten crystal ingots, 15 cm with weights progressing to 27 kg.

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

    Science.gov (United States)

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

    1991-01-01

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

  12. Crystal Growth Technology

    Science.gov (United States)

    Scheel, Hans J.; Fukuda, Tsuguo

    2004-06-01

    This volume deals with the technologies of crystal fabrication, of crystal machining, and of epilayer production and is the first book on industrial and scientific aspects of crystal and layer production. The major industrial crystals are treated: Si, GaAs, GaP, InP, CdTe, sapphire, oxide and halide scintillator crystals, crystals for optical, piezoelectric and microwave applications and more. Contains 29 contributions from leading crystal technologists covering the following topics: General aspects of crystal growth technology Silicon Compound semiconductors Oxides and halides Crystal machining Epitaxy and layer deposition Scientific and technological problems of production and machining of industrial crystals are discussed by top experts, most of them from the major growth industries and crystal growth centers. In addition, it will be useful for the users of crystals, for teachers and graduate students in materials sciences, in electronic and other functional materials, chemical and metallurgical engineering, micro-and optoelectronics including nanotechnology, mechanical engineering and precision-machining, microtechnology, and in solid-state sciences.

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

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  14. Influence of Containment on the Growth of Silicon-Germanium (ICESAGE): A Materials Science Investigation

    Science.gov (United States)

    Volz, M. P.; Mazuruk, K.; Croll, A.

    2014-01-01

    A series of Ge Si crystal growth experiments are planned to be conducted in the Low 1-x x Gradient Furnace (LGF) onboard the International Space Station. The primary objective of the research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. The existence of this meniscus depends on the ratio of the strength of gravity to capillary forces. On Earth, this ratio is large and stable detached growth can only be obtained over limited conditions. Crystals grown detached on the ground exhibited superior structural quality as evidenced by measurements of etch pit density, synchrotron white beam X-ray topography and double axis X-ray diffraction.

  15. Collimation: a silicon solution

    CERN Multimedia

    2007-01-01

    Silicon crystals could be used very efficiently to deflect high-energy beams. Testing at CERN has produced conclusive results, which could pave the way for a new generation of collimators. The set of five crystals used to test the reflection of the beams. The crystals are 0.75 mm wide and their alignment is adjusted with extreme precision. This figure shows the deflection of a beam by channelling and by reflection in the block of five crystals. Depending on the orientation of the crystals: 1) The beam passes without "seeing" the crystals and is not deflected 2) The beam is deflected by channelling (with an angle of around 100 μrad) 3) The beam is reflected (with an angle of around 50 μrad). The intensity of the deflected beam is illustrated by the intensity of the spot. The spot of the reflected beam is clearly more intense than that one of the channelled beam, demonstrating the efficiency of t...

  16. Global and Local Loss Suppression in the UA9 Crystal Collimation Experiment

    CERN Document Server

    Montesano, S

    2012-01-01

    UA9 was operated in the CERN-SPS for some years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Silicon crystals 2 mm long with bending angles of about 150 μrad are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency. The loss profiles in the area of the crystal collimator setup and in the downstream dispersion suppressor area show a steady reduction of slightly less than one order of magnitude at the onset of the channeling process. This result holds both for protons and for lead ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency in hadron colliders, such as LHC.

  17. Thermal equilibrium concentration of intrinsic point defects in heavily doped silicon crystals - Theoretical study of formation energy and formation entropy in area of influence of dopant atoms-

    Science.gov (United States)

    Kobayashi, K.; Yamaoka, S.; Sueoka, K.; Vanhellemont, J.

    2017-09-01

    It is well known that p-type, neutral and n-type dopants affect the intrinsic point defect (vacancy V and self-interstitial I) behavior in single crystal Si. By the interaction with V and/or I, (1) growing Si crystals become more V- or I-rich, (2) oxygen precipitation is enhanced or retarded, and (3) dopant diffusion is enhanced or retarded, depending on the type and concentration of dopant atoms. Since these interactions affect a wide range of Si properties ranging from as-grown crystal quality to LSI performance, numerical simulations are used to predict and to control the behavior of both dopant atoms and intrinsic point defects. In most cases, the thermal equilibrium concentrations of dopant-point defect pairs are evaluated using the mass action law by taking only the binding energy of closest pair to each other into account. The impacts of dopant atoms on the formation of V and I more distant than 1st neighbor and on the change of formation entropy are usually neglected. In this study, we have evaluated the thermal equilibrium concentrations of intrinsic point defects in heavily doped Si crystals. Density functional theory (DFT) calculations were performed to obtain the formation energy (Ef) of the uncharged V and I at all sites in a 64-atom supercell around a substitutional p-type (B, Ga, In, and Tl), neutral (C, Ge, and Sn) and n-type (P, As, and Sb) dopant atom. The formation (vibration) entropies (Sf) of free I, V and I, V at 1st neighboring site from B, C, Sn, P and As atoms were also calculated with the linear response method. The dependences of the thermal equilibrium concentrations of trapped and total intrinsic point defects (sum of free I or V and I or V trapped with dopant atoms) on the concentrations of B, C, Sn, P and As in Si were obtained. Furthermore, the present evaluations well explain the experimental results of the so-called ;Voronkov criterion; in B and C doped Si, and also the observed dopant dependent void sizes in P and As doped Si

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

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  19. Network diversity through two-step crystal engineering of a decorated 6-connected primary molecular building block

    KAUST Repository

    Yang, Qing-Yuan; Chen, Kai-Jie; Schoedel, Alexander; Wojtas, Lukasz; Perry IV, John J.; Zaworotko, Michael J.

    2016-01-01

    [Cr3O(nicotinate)6]+ was isolated and then utilised as a new primary molecular building block, PMBB, linked by 2-, 3- and 4-connected metal centres. Five novel metal–organic materials (MOMs) with acs, stp, rtl, fsc and pcu topologies were thereby isolated and characterised.

  20. Network diversity through two-step crystal engineering of a decorated 6-connected primary molecular building block

    KAUST Repository

    Yang, Qing-Yuan

    2016-10-04

    [Cr3O(nicotinate)6]+ was isolated and then utilised as a new primary molecular building block, PMBB, linked by 2-, 3- and 4-connected metal centres. Five novel metal–organic materials (MOMs) with acs, stp, rtl, fsc and pcu topologies were thereby isolated and characterised.

  1. Porous silicon investigated by positron annihilation

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  2. Semiconductors and semimetals oxygen in silicon

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Shimura, Fumio

    1994-01-01

    This volume reviews the latest understanding of the behavior and roles of oxygen in silicon, which will carry the field into the ULSI era from the experimental and theoretical points of view. The fourteen chapters, written by recognized authorities representing industrial and academic institutions, cover thoroughly the oxygen related phenomena from the crystal growth to device fabrication processes, as well as indispensable diagnostic techniques for oxygen.Key Features* Comprehensive study of the behavior of oxygen in silicon* Discusses silicon crystals for VLSI and ULSI applications* Thorough coverage from crystal growth to device fabrication* Edited by technical experts in the field* Written by recognized authorities from industrial and academic institutions* Useful to graduate students, scientists in other disciplines, and active participants in the arena of silicon-based microelectronics research* 297 original line drawings

  3. CHANNELING OF B-IONS IN SILICON

    NARCIS (Netherlands)

    VOS, M; MITCHELL, [No Value; SMULDERS, PJM

    We present new results on the channeling of B ions in Si crystals. Standard surface barrier detectors have been used to record energy spectra for B ions backscattered from the near surface (approximately 1500 angstrom) of a silicon crystal, under perfect, and near axial and planar channeling

  4. The LHCb Silicon Tracker

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, Mark, E-mail: Mark.Tobin@epfl.ch

    2016-09-21

    The LHCb experiment is dedicated to the study of heavy flavour physics at the Large Hadron Collider (LHC). The primary goal of the experiment is to search for indirect evidence of new physics via measurements of CP violation and rare decays of beauty and charm hadrons. The LHCb detector has a large-area silicon micro-strip detector located upstream of a dipole magnet, and three tracking stations with silicon micro-strip detectors in the innermost region downstream of the magnet. These two sub-detectors form the LHCb Silicon Tracker (ST). This paper gives an overview of the performance and operation of the ST during LHC Run 1. Measurements of the observed radiation damage are shown and compared to the expectation from simulation.

  5. Passivating electron contact based on highly crystalline nanostructured silicon oxide layers for silicon solar cells

    Czech Academy of Sciences Publication Activity Database

    Stuckelberger, J.; Nogay, G.; Wyss, P.; Jeangros, Q.; Allebe, Ch.; Debrot, F.; Niquille, X.; Ledinský, Martin; Fejfar, Antonín; Despeisse, M.; Haug, F.J.; Löper, P.; Ballif, C.

    2016-01-01

    Roč. 158, Dec (2016), s. 2-10 ISSN 0927-0248 R&D Projects: GA MŠk LM2015087 Institutional support: RVO:68378271 Keywords : surface passivation * passivating contact * nanostructure * silicon oxide * nanocrystalline * microcrystalline * poly-silicon * crystallization * Raman * transmission line measurement Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.784, year: 2016

  6. Silumins alloy crystallization

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2009-07-01

    Full Text Available This paper presents the results of research, by ATD method, of hypo-, near- and hyperutectic silumins crystallization containing the following alloying additives: Mg, Ni, Cu, Cr, Mo, W, V. It has been shown that, depending on their concentration may crystallize pre-eutectic or eutectic multicomponent phases containing these alloy additives. It has been revealed that any subsequent crystallizable phase nucleate and grows near the liquid/former crystallized phase interface. In multiphases compound also falls the silicon, resulting in a reduction in its quantity and the fragmentation in the eutectic mixture. As a result, it gets a high hardness of silumins in terms of 110-220HB.

  7. Apparatus for making molten silicon

    Science.gov (United States)

    Levin, Harry (Inventor)

    1988-01-01

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

  8. Economic analysis of crystal growth in space

    Science.gov (United States)

    Ulrich, D. R.; Chung, A. M.; Yan, C. S.; Mccreight, L. R.

    1972-01-01

    Many advanced electronic technologies and devices for the 1980's are based on sophisticated compound single crystals, i.e. ceramic oxides and compound semiconductors. Space processing of these electronic crystals with maximum perfection, purity, and size is suggested. No ecomonic or technical justification was found for the growth of silicon single crystals for solid state electronic devices in space.

  9. Sintering of nano crystalline α silicon carbide by doping with boron ...

    Indian Academy of Sciences (India)

    Unknown

    tions, they concluded that either reaction sintering or liquid phase .... α-6H silicon carbide single crystal by three different laboratories ... silicon carbide particles by the overall reaction .... layer displacement is likely to occur in such a manner as.

  10. Anamorphic and Local Characterization of a Holographic Data Storage System with a Liquid-Crystal on Silicon Microdisplay as Data Pager

    Directory of Open Access Journals (Sweden)

    Fco. Javier Martínez-Guardiola

    2018-06-01

    Full Text Available In this paper, we present a method to characterize a complete optical Holographic Data Storage System (HDSS, where we identify the elements that limit the capacity to register and restore the information introduced by means of a Liquid Cristal on Silicon (LCoS microdisplay as the data pager. In the literature, it has been shown that LCoS exhibits an anamorphic and frequency dependent effect when periodic optical elements are addressed to LCoS microdisplays in diffractive optics applications. We tested whether this effect is still relevant in the application to HDSS, where non-periodic binary elements are applied, as it is the case in binary data pages codified by Binary Intensity Modulation (BIM. To test the limits in storage data density and in spatial bandwidth of the HDSS, we used anamorphic patterns with different resolutions. We analyzed the performance of the microdisplay in situ using figures of merit adapted to HDSS. A local characterization across the aperture of the system was also demonstrated with our proposed methodology, which results in an estimation of the illumination uniformity and the contrast generated by the LCoS. We show the extent of the increase in the Bit Error Rate (BER when introducing a photopolymer as the recording material, thus all the important elements in a HDSS are considered in the characterization methodology demonstrated in this paper.

  11. Low temperature perovskite crystallization of highly tunable dielectric Ba0.7Sr0.3TiO3 thick films deposited by ion beam sputtering on platinized silicon substrates

    Science.gov (United States)

    Zhu, X. H.; Guigues, B.; Defaÿ, E.; Dubarry, C.; Aïd, M.

    2009-02-01

    Ba0.7Sr0.3TiO3 (BST) thick films with thickness up to 1 μm were deposited on Pt-coated silicon substrates by ion beam sputtering, followed by an annealing treatment. It is demonstrated that pure well-crystallized perovskite phase could be obtained in thick BST films by a low temperature process (535 °C). The BST thick films show highly tunable dielectric properties with tunability (at 800 kV/cm) up to 51.0% and 66.2%, respectively, for the 0.5 and 1 μm thick films. The relationship between strains and dielectric properties was systematically investigated in the thick films. The results suggest that a comparatively larger tensile thermal in-plane strain (0.15%) leads to the degradation in dielectric properties of the 0.5 μm thick film; besides, strong defect-related inhomogeneous strains (˜0.3%) make the dielectric peaks smearing and broadening in the thick films, which, however, preferably results in high figure-of-merit factors over a wide operating temperature range. Moreover, the leakage current behavior in the BST thick films was found to be dominated by the space-charge-limited-current mechanism, irrespective of the film thickness.

  12. Low temperature perovskite crystallization of highly tunable dielectric Ba0.7Sr0.3TiO3 thick films deposited by ion beam sputtering on platinized silicon substrates

    International Nuclear Information System (INIS)

    Zhu, X. H.; Defaye, E.; Aied, M.; Guigues, B.; Dubarry, C.

    2009-01-01

    Ba 0.7 Sr 0.3 TiO 3 (BST) thick films with thickness up to 1 μm were deposited on Pt-coated silicon substrates by ion beam sputtering, followed by an annealing treatment. It is demonstrated that pure well-crystallized perovskite phase could be obtained in thick BST films by a low temperature process (535 deg. C). The BST thick films show highly tunable dielectric properties with tunability (at 800 kV/cm) up to 51.0% and 66.2%, respectively, for the 0.5 and 1 μm thick films. The relationship between strains and dielectric properties was systematically investigated in the thick films. The results suggest that a comparatively larger tensile thermal in-plane strain (0.15%) leads to the degradation in dielectric properties of the 0.5 μm thick film; besides, strong defect-related inhomogeneous strains (∼0.3%) make the dielectric peaks smearing and broadening in the thick films, which, however, preferably results in high figure-of-merit factors over a wide operating temperature range. Moreover, the leakage current behavior in the BST thick films was found to be dominated by the space-charge-limited-current mechanism, irrespective of the film thickness

  13. Strained silicon as a new electro-optic material

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  14. Development of advanced Czochralski growth process to produce low cost 150 kg silicon ingots from a single crucible for technology readiness. [crystal growth

    Science.gov (United States)

    Lane, R. L.

    1981-01-01

    Six growth runs used the Kayex-Hameo Automatic Games Logic (AGILE) computer based system for growth from larger melts in the Mod CG2000. The implementation of the melt pyrometer sensor allowed for dip temperature monitoring and usage by the operator/AGILE system. Use of AGILE during recharge operations was successfully evaluated. The tendency of crystals to lose cylindrical shape (spiraling) continued to be a problem. The hygrometer was added to the Furnace Gas Analysis System and used on several growth runs. The gas chromatograph, including the integrator, was also used for more accurate carbon monoxide concentration measurements. Efforts continued for completing the automation of the total Gas Analysis System. An economic analysis, based on revised achievable straight growth rate, is presented.

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

    International Nuclear Information System (INIS)

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

    1986-04-01

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

  16. Induced high-order resonance linewidth shrinking with multiple coupled resonators in silicon-organic hybrid slotted two-dimensional photonic crystals for reduced optical switching power in bistable devices

    Science.gov (United States)

    Hoang, Thu Trang; Ngo, Quang Minh; Vu, Dinh Lam; Le, Khai Q.; Nguyen, Truong Khang; Nguyen, Hieu P. T.

    2018-01-01

    Shrinking the linewidth of resonances induced by multiple coupled resonators is comprehensively analyzed using the coupled-mode theory (CMT) in time. Two types of coupled resonators under investigation are coupled resonator optical waveguides (CROWs) and side-coupled resonators with waveguide (SCREW). We examine the main parameters influencing on the spectral response such as the number of resonators (n) and the phase shift (φ) between two adjacent resonators. For the CROWs geometry consisting of n coupled resonators, we observe the quality (Q) factor of the right- and left-most resonant lineshapes increases n times larger than that of a single resonator. For the SCREW geometry, relying on the phase shift, sharp, and asymmetric resonant lineshape of the high Q factor a narrow linewidth of the spectral response could be achieved. We employ the finite-difference time-domain (FDTD) method to design and simulate two proposed resonators for practical applications. The proposed coupled resonators in silicon-on-insulator (SOI) slotted two-dimensional (2-D) photonic crystals (PhCs) filled and covered with a low refractive index organic material. Slotted PhC waveguides and cavities are designed to enhance the electromagnetic intensity and to confine the light into small cross-sectional area with low refractive index so that efficient optical devices could be achieved. A good agreement between the theoretical CMT analysis and the FDTD simulation is shown as an evidence for our accurate investigation. All-optical switches based on the CROWs in the SOI slotted 2-D PhC waveguide that are filled and covered by a nonlinear organic cladding to overcome the limitations of its well-known intrinsic properties are also presented. From the calculations, we introduce a dependency of the normalized linewidth of the right-most resonance and its switching power of the all-optical switches on number of resonator, n. This result might provide a guideline for all-optical signal processing on

  17. Crystal Collimation Cleaning Measurements with Proton Beams in LHC

    CERN Document Server

    Rossi, Roberto; Andreassen, Odd Oyvind; Butcher, Mark; Dionisio Barreto, Cristovao Andre; Masi, Alessandro; Mirarchi, Daniele; Montesano, Simone; Lamas Garcia, Inigo; Redaelli, Stefano; Scandale, Walter; Serrano Galvez, Pablo; Rijllart, Adriaan; Valentino, Gianluca; CERN. Geneva. ATS Department

    2016-01-01

    During this MD, performed on July 29th, 2016, bent silicon crystal were tested with proton beams for a possible usage of crystal-assisted collimation. Tests were performed at both injection energy and flat top using horizontal and vertical crystal. Loss maps with crystals at 6.5 TeV were measured.

  18. Modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium

    Energy Technology Data Exchange (ETDEWEB)

    Patakham, Ussadawut [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand); Kajornchaiyakul, Julathep [National Metal and Material Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@kmutt.ac.th [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

    2013-10-25

    Highlights: •Morphologies and growth of Sc and Sr-modified eutectic silicon resemble those of dendrites. •Crystal orientation of eutectic aluminum depends on growth characteristics of eutectic silicon. •We report strong evidence of the occurrence of an impurity-induced twinning mechanism. -- Abstract: The modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium was studied. The crystallographic orientation relationships between primary dendrites and the eutectic phase of unmodified and modified Al–6Si–0.3 Mg alloys were determined using electron backscatter diffraction (EBSD). The orientation of aluminum modified with scandium in the eutectic phase was different from that of the neighboring primary dendrites. This result implies that eutectic aluminum grows epitaxially from the surrounding primary aluminum dendrites in the unmodified alloy and that eutectic aluminum grows competitively from the surrounding primary aluminum dendrites in the modified alloy. The pole figure maps of eutectic Si in the [1 0 0], [1 1 0] and [1 1 1] axes of the unmodified and Sc-modified alloys were different, suggesting that the eutectic Al and Si crystals in modified alloy growth are more isotropic and cover a larger set of directions. The lattice fringes of Si of the alloys with and without Sc modification were different in the TEM results. The lattice fringes of Si in modified alloy were found to be multiple twins. However, this was not observed in the unmodified alloy. The growth characteristic of eutectic Si crystal in modified alloy suggests the occurrence of multiple twinning reactions and the formation of a high density of twins. This modification mechanism by Sc is explained by the results of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis, which provide strong evidence of the occurrence of the impurity-induced twinning (IIT) mechanism.

  19. Molecular orbital study of the primary electron donor P700 of photosystem I based on a recent X-ray single crystal structure analysis

    International Nuclear Information System (INIS)

    Plato, Martin; Krauss, Norbert; Fromme, Petra; Lubitz, Wolfgang

    2003-01-01

    The X-ray structure analysis of photosystem (PS) I single crystals showed that the primary electron donor P700 is a heterodimer formed by one chlorophyll (Chl) a and one Chl a ' [Nature 411 (2001) 909]. The electronic structure of the cation radical P700 +· of the primary donor, which is created in the charge separation process, has been probed by semiempirical molecular orbital calculations including spin polarization effects (RHF-INDO/SP). The calculations, which were based on the X-ray structure, clearly show that P700 is a supermolecule formed by two chlorophyll species. They furthermore predict an asymmetrical charge and spin density distribution in favor of the monomeric Chl a half of this dimer in accordance with results from earlier EPR and ENDOR studies [J. Phys. Chem. B 105 (2000) 1225]. The stepwise inclusion of various electrostatic interactions of the dimer with its nearest surrounding (one threonine forming a hydrogen bond to the keto group of Chl a ' and two histidines liganding the Mg atoms of the two chlorophylls) leads to a systematic enhancement of this electronic asymmetry yielding a spin density ratio of almost 5:1 as also found experimentally. A large part of this value is caused by spin polarization effects. This result is only weakly affected by the electrostatic field of more remote amino acid residues and other pigment molecules ('accessory' Chl a molecules) present in PS I. A separate group of calculations involving local geometry optimizations by energy minimization techniques yields a further enhancement of the spin density asymmetry. A particularly strong effect is obtained by allowing for variations of the geometry of the vinyl groups on both chlorophylls of the P700 dimer. Theoretical results for individual isotropic proton and nitrogen hyperfine coupling constants, showing a satisfactory agreement with experimental findings, are also presented

  20. 晶硅太阳能光伏电池生产的职业危害特点及其防控对策%Characteristics and Control Strategies of Occupational Hazards in Crystal Silicon Solar Energy Photovoltaic Battery Production

    Institute of Scientific and Technical Information of China (English)

    戴云; 朱素蓉; 陈喆; 王强毅

    2012-01-01

    [ Objective ] To investigate the status and features of occupational hazards in crystal silicon solar energy photovoltaic battery production, and to explore solutions for the improvement of occupational hazard control strategies. [ Methods ] A survey on technology, hygienic engineering measures, occupational health surveillance and management was conducted in 4 crystal silicon solar energy photovoltaic battery manufacturing plants in Shanghai, where the concentration (level) of occupational hazard factor was also monitored. [ Results ] The technology of solar energy photovoltaic battery was complicated and involved more than 20 kinds of materials. The workers were exposed to various irritant chemicals and dusts, half of which were severe or moderate poisons. All of the 4 plants took certain hygienic engineering measures and basically established health surveillance and hygienic management system. All the occupational hazard concentrations (levels) were significantly below the national allowable occupational exposure levels (OELs) except that of carborundum in sand-blast shop. [ Conclusion ] The occupational health management of the 4 manufacturing plants is in line with the regulatory requirements, but potential hazards of occupational diseases should not be ignored. It is necessary to further improve the prevention and control measures for occupational hazards.%[目的]调查晶硅太阳能光伏电池生产的职业危害特点和现状,并对进一步健全和完善职业危害防控策略进行探讨.[方法]对上海市4家从事晶硅太阳能光伏电池生产企业的生产工艺、卫生工程防护措施、职业健康监护和职业卫生管理制度等现状进行调查,并对作业场所职业病危害因素浓度(强度)进行检测.[结果]晶硅太阳能光伏电池生产工艺较为复杂,涉及的原、辅料多达20余种,员工在生产过程中可能接触到多种刺激性化学毒物和多种粉尘,且其中一半以上为中毒或高毒物

  1. Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

    International Nuclear Information System (INIS)

    Gentile, C.A.; Fan, H.M.; Hartfield, J.W.; Hawryluk, R.J.; Hegeler, F.; Heitzenroeder, P.J.; Jun, C.H.; Ku, L.P.; LaMarche, P.H.; Myers, M.C.; Parker, J.J.; Parsells, R.F.; Payen, M.; Raftopoulos, S.; Sethian, J.D.

    2002-01-01

    The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W · cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated with 500 nm thin-film silicon nitride (Si 3 N 4 ), has been fabricated. The window consists of 81 square panes with a thickness of 0.019 mm ± 0.001 mm. Stiffened (orthogonal) sections are 0.065 mm in width and 0.500 mm thick (approximate). Appended drawing (Figure 1) depicts the window configuration. Assessment of silicon (and silicon nitride) material properties and CAD modeling and analysis of the window design suggest that silicon may be a viable solution to inherent parameters and constraints

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

    Science.gov (United States)

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

    1979-01-01

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

  3. Crystal Structure of the Zorbamycin-Binding Protein ZbmA, the Primary Self-Resistance Element in Streptomyces flavoviridis ATCC21892

    Energy Technology Data Exchange (ETDEWEB)

    Rudolf, Jeffrey D. [Scripps Research Inst., Jupiter, FL (United States); Bigelow, Lance [Argonne National Lab. (ANL), Argonne, IL (United States); Chang, Changsoo [Argonne National Lab. (ANL), Argonne, IL (United States); Cuff, Marianne E. [Argonne National Lab. (ANL), Argonne, IL (United States); Lohman, Jeremy R. [Scripps Research Inst., Jupiter, FL (United States); Chang, Chin-Yuan [Scripps Research Inst., Jupiter, FL (United States); Ma, Ming [Scripps Research Inst., Jupiter, FL (United States); Yang, Dong [Scripps Research Inst., Jupiter, FL (United States); Clancy, Shonda [Argonne National Lab. (ANL), Argonne, IL (United States); Babnigg, Gyorgy [Argonne National Lab. (ANL), Argonne, IL (United States); Joachimiak, Andrzej [Argonne National Lab. (ANL), Argonne, IL (United States); Phillips, George N. [Rice Univ., Houston, TX (United States); Shen, Ben [Scripps Research Inst., Jupiter, FL (United States)

    2015-11-17

    The bleomycins (BLMs), tallysomycins (TLMs), phleomycin, and zorbamycin (ZBM) are members of the BLM family of glycopeptide-derived antitumor antibiotics. The BLM-producing Streptomyces verticillus ATCC15003 and the TLM-producing Streptoalloteichus hindustanus E465-94 ATCC31158 both possess at least two self-resistance elements, an N-acetyltransferase and a binding protein. The N-acetyltransferase provides resistance by disrupting the metal-binding domain of the antibiotic that is required for activity, while the binding protein confers resistance by sequestering the metal-bound antibiotic and preventing drug activation via molecular oxygen. We recently established that the ZBM producer, Streptomyces flavoviridis ATCC21892, lacks the N-acetyltransferase resistance gene and that the ZBM-binding protein, ZbmA, is sufficient to confer resistance in the producing strain. To investigate the resistance mechanism attributed to ZbmA, we determined the crystal structures of apo and Cu(II)-ZBM-bound ZbmA at high resolutions of 1.90 and 1.65 angstrom, respectively. A comparison and contrast with other structurally characterized members of the BLM-binding protein family revealed key differences in the protein ligand binding environment that fine-tunes the ability of ZbmA to sequester metal-bound ZBM and supports drug sequestration as the primary resistance mechanism in the producing organisms of the BLM family of antitumor antibiotics.

  4. Silicon Qubits

    Energy Technology Data Exchange (ETDEWEB)

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

    2018-02-28

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

  5. Silicon radiation detectors: materials and applications

    International Nuclear Information System (INIS)

    Walton, J.T.; Haller, E.E.

    1982-10-01

    Silicon nuclear radiation detectors are available today in a large variety of sizes and types. This profusion has been made possible by the ever increasing quality and diameter silicon single crystals, new processing technologies and techniques, and innovative detector design. The salient characteristics of the four basic detector groups, diffused junction, ion implanted, surface barrier, and lithium drift are reviewed along with the silicon crystal requirements. Results of crystal imperfections detected by lithium ion compensation are presented. Processing technologies and techniques are described. Two recent novel position-sensitive detector designs are discussed - one in high-energy particle track reconstruction and the other in x-ray angiography. The unique experimental results obtained with these devices are presented

  6. Attenuation of Thermal Neutrons by Crystalline Silicon

    International Nuclear Information System (INIS)

    Adib, M.; Habib, N.; Ashry, A.; Fathalla, M.

    2002-01-01

    A simple formula is given which allows to calculate the contribution of the total neutron cross - section including the Bragg scattering from different (hkt) planes to the neutron * transmission through a solid crystalline silicon. The formula takes into account the silicon form of poly or mono crystals and its parameters. A computer program DSIC was developed to provide the required calculations. The calculated values of the total neutron cross-section of perfect silicon crystal at room and liquid nitrogen temperatures were compared with the experimental ones. The obtained agreement shows that the simple formula fits the experimental data with sufficient accuracy .A good agreement was also obtained between the calculated and measured values of polycrystalline silicon in the energy range from 5 eV to 500μ eV. The feasibility study on using a poly-crystalline silicon as a cold neutron filter and mono-crystalline as a thermal neutron one is given. The optimum crystal thickness, mosaic spread, temperature and cutting plane for efficiently transmitting the thermal reactor neutrons, while rejecting both fast neutrons and gamma rays accompanying the thermal ones for the mono crystalline silicon are also given

  7. Transistors using crystalline silicon devices on glass

    Science.gov (United States)

    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.

  8. Amorphization of silicon by femtosecond laser pulses

    International Nuclear Information System (INIS)

    Jia, Jimmy; Li Ming; Thompson, Carl V.

    2004-01-01

    We have used femtosecond laser pulses to drill submicron holes in single crystal silicon films in silicon-on-insulator structures. Cross-sectional transmission electron microscopy and energy dispersive x-ray analysis of material adjacent to the ablated holes indicates the formation of a layer of amorphous Si. This demonstrates that even when material is ablated using femtosecond pulses near the single pulse ablation threshold, sufficient heating of the surrounding material occurs to create a molten zone which solidifies so rapidly that crystallization is bypassed

  9. Making Porous Luminescent Regions In Silicon Wafers

    Science.gov (United States)

    Fathauer, Robert W.; Jones, Eric W.

    1994-01-01

    Regions damaged by ion implantation stain-etched. Porous regions within single-crystal silicon wafers fabricated by straightforward stain-etching process. Regions exhibit visible photoluminescence at room temperature and might constitute basis of novel class of optoelectronic devices. Stain-etching process has advantages over recently investigated anodic-etching process. Process works on both n-doped and p-doped silicon wafers. Related development reported in article, "Porous Si(x)Ge(1-x) Layers Within Single Crystals of Si," (NPO-18836).

  10. Electrical properties of pressure quenched silicon by thermal spraying

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  11. Silicon radiation detector analysis using back electron beam induced current

    International Nuclear Information System (INIS)

    Guye, R.

    1987-01-01

    A new technique for the observation and analysis of defects in silicon radiation detectors is described. This method uses an electron beam from a scanning electron microscope (SEM) impinging on the rear side of the p + n junction of the silicon detector, which itself is active and detects the electron beam induced current (EBIC). It is shown that this current is a sensitive probe of localized trapping centers, either at the junction surface or somewhere in the volume of the silicon crystal. (orig.)

  12. Crystal structure of the S187F variant of human liver alanine: Aminotransferase associated with primary hyperoxaluria type I and its functional implications

    Science.gov (United States)

    Oppici, Elisa; Fodor, Krisztian; Paiardini, Alessandro; Williams, Chris; Voltattorni, Carla Borri; Wilmanns, Matthias; Cellini, Barbara

    2013-01-01

    The substitution of Ser187, a residue located far from the active site of human liver peroxisomal alanine:glyoxylate aminotransferase (AGT), by Phe gives rise to a variant associated with primary hyperoxaluria type I. Unexpectedly, previous studies revealed that the recombinant form of S187F exhibits a remarkable loss of catalytic activity, an increased pyridoxal 5′-phosphate (PLP) binding affinity and a different coenzyme binding mode compared with normal AGT. To shed light on the structural elements responsible for these defects, we solved the crystal structure of the variant to a resolution of 2.9 Å. Although the overall conformation of the variant is similar to that of normal AGT, we noticed: (i) a displacement of the PLP-binding Lys209 and Val185, located on the re and si side of PLP, respectively, and (ii) slight conformational changes of other active site residues, in particular Trp108, the base stacking residue with the pyridine cofactor moiety. This active site perturbation results in a mispositioning of the AGT-pyridoxamine 5′-phosphate (PMP) complex and of the external aldimine, as predicted by molecular modeling studies. Taken together, both predicted and observed movements caused by the S187F mutation are consistent with the following functional properties of the variant: (i) a 300- to 500-fold decrease in both the rate constant of L-alanine half-transamination and the kcat of the overall transamination, (ii) a different PMP binding mode and affinity, and (iii) a different microenvironment of the external aldimine. Proposals for the treatment of patients bearing S187F mutation are discussed on the basis of these results. Proteins 2013; 81:1457–1465. © 2013 Wiley Periodicals, Inc. PMID:23589421

  13. A review of manufacturing metrology for improved reliability of silicon photovoltaic modules

    Science.gov (United States)

    Davis, Kristopher O.; Walters, Joseph; Schneller, Eric; Seigneur, Hubert; Brooker, R. Paul; Scardera, Giuseppe; Rodgers, Marianne P.; Mohajeri, Nahid; Shiradkar, Narendra; Dhere, Neelkanth G.; Wohlgemuth, John; Rudack, Andrew C.; Schoenfeld, Winston V.

    2014-10-01

    In this work, the use of manufacturing metrology across the supply chain to improve crystalline silicon (c-Si) photovoltaic (PV) module reliability and durability is addressed. Additionally, an overview and summary of a recent extensive literature survey of relevant measurement techniques aimed at reducing or eliminating the probability of field failures is presented. An assessment of potential gaps is also given, wherein the PV community could benefit from new research and demonstration efforts. This review is divided into three primary areas representing different parts of the c-Si PV supply chain: (1) feedstock production, crystallization and wafering; (2) cell manufacturing; and (3) module manufacturing.

  14. Czochralski method of growing single crystals. State-of-art

    International Nuclear Information System (INIS)

    Bukowski, A.; Zabierowski, P.

    1999-01-01

    Modern Czochralski method of single crystal growing has been described. The example of Czochralski process is given. The advantages that caused the rapid progress of the method have been presented. The method limitations that motivated the further research and new solutions are also presented. As the example two different ways of the technique development has been described: silicon single crystals growth in the magnetic field; continuous liquid feed of silicon crystals growth. (author)

  15. Nanofabrication of Arrays of Silicon Field Emitters with Vertical Silicon Nanowire Current Limiters and Self-Aligned Gates

    Science.gov (United States)

    2016-08-19

    limiters, MEMS, NEMS, field emission, cold cathodes (Some figures may appear in colour only in the online journal) 1. Introduction Dense arrays of silicon... attention has been given to densely packed, highly ordered, top-down fabricated, single crystal vertical silicon nanowire devices that are embedded

  16. Improving the Microstructure and Electrical Properties of Aluminum Induced Polysilicon Thin Films Using Silicon Nitride Capping Layer

    Directory of Open Access Journals (Sweden)

    Min-Hang Weng

    2014-01-01

    Full Text Available We investigated the capping layer effect of SiNx (silicon nitride on the microstructure, electrical, and optical properties of poly-Si (polycrystalline silicon prepared by aluminum induced crystallization (AIC. The primary multilayer structure comprised Al (30 nm/SiNx (20 nm/a-Si (amorphous silicon layer (100 nm/ITO coated glass and was then annealed in a low annealing temperature of 350°C with different annealing times, 15, 30, 45, and 60 min. The crystallization properties were analyzed and verified by X-ray diffraction (XRD and Raman spectra. The grain growth was analyzed via optical microscope (OM and scanning electron microscopy (SEM. The improved electrical properties such as Hall mobility, resistivity, and dark conductivity were investigated by using Hall and current-voltage (I-V measurements. The results show that the amorphous silicon film has been effectively induced even at a low temperature of 350°C and a short annealing time of 15 min and indicate that the SiNx capping layer can improve the grain growth and reduce the metal content in the induced poly-Si film. It is found that the large grain size is over 20 μm and the carrier mobility values are over 80 cm2/V-s.

  17. Increased carrier lifetimes in epitaxial silicon layers on buried silicon nitride produced by ion implantation

    International Nuclear Information System (INIS)

    Skorupa, W.; Kreissig, U.; Hensel, E.; Bartsch, H.

    1984-01-01

    Carrier lifetimes were measured in epitaxial silicon layers deposited on buried silicon nitride produced by high-dose nitrogen implantation at 330 keV. The values were in the range 20-200 μs. The results are remarkable taking into account the high density of crystal defects in the epitaxial layers. Comparing with other SOI technologies the measured lifetimes are higher by 1-2 orders of magnitude. (author)

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

    Science.gov (United States)

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

    1997-01-01

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

  19. Porous silicon: Synthesis and optical properties

    International Nuclear Information System (INIS)

    Naddaf, M.; Awad, F.

    2006-01-01

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

  20. Porous silicon: Synthesis and optical properties

    International Nuclear Information System (INIS)

    Naddaf, M.; Awad, F.

    2006-06-01

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

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

    Science.gov (United States)

    Buriak, Jillian M

    2006-01-15

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

  2. Influence of Containment on the Growth of Silicon-Germanium: A Materials Science Flight Project

    Science.gov (United States)

    Volz, M. P.; Mazuruk, K.; Croell, A.

    2012-01-01

    A series of Ge(1-x)Si(x) crystal growth experiments are planned to be conducted in the Low Gradient Furnace (LGF) onboard the International Space Station. The primary objective of the research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. The existence of this meniscus depends on the ratio of the strength of gravity to capillary forces. On Earth, this ratio is large and stable detached growth can only be obtained over limited conditions. Crystals grown detached on the ground exhibited superior structural quality as evidenced by measurements of etch pit density, synchrotron white beam X-ray topography and double axis X-ray diffraction. The plans for the flight experiments will be described.

  3. Influence of Containment on the Growth of Silicon-Germanium (ICESAGE): A Materials Science ISS Investigation

    Science.gov (United States)

    Volz, M. P.; Mazuruk, K.; Croll, A.

    2014-01-01

    A series of Ge(1-x)Si(x) crystal growth experiments are planned to be conducted in the Low Gradient Furnace (LGF) onboard the International Space Station. The primary objective of the research is to determine the influence of containment on the processinginduced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. The existence of this meniscus depends on the ratio of the strength of gravity to capillary forces. On Earth, this ratio is large and stable detached growth can only be obtained over limited conditions. Crystals grown detached on the ground exhibited superior structural quality as evidenced by measurements of etch pit density, synchrotron white beam X-ray topography and double axis X-ray diffraction. The plans for the flight experiments will be described.

  4. Quantum mechanical theory of epitaxial transformation of silicon to silicon carbide

    International Nuclear Information System (INIS)

    Kukushkin, S A; Osipov, A V

    2017-01-01

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

  5. Shrinking of silicon nanocrystals embedded in an amorphous silicon oxide matrix during rapid thermal annealing in a forming gas atmosphere

    Science.gov (United States)

    van Sebille, M.; Fusi, A.; Xie, L.; Ali, H.; van Swaaij, R. A. C. M. M.; Leifer, K.; Zeman, M.

    2016-09-01

    We report the effect of hydrogen on the crystallization process of silicon nanocrystals embedded in a silicon oxide matrix. We show that hydrogen gas during annealing leads to a lower sub-band gap absorption, indicating passivation of defects created during annealing. Samples annealed in pure nitrogen show expected trends according to crystallization theory. Samples annealed in forming gas, however, deviate from this trend. Their crystallinity decreases for increased annealing time. Furthermore, we observe a decrease in the mean nanocrystal size and the size distribution broadens, indicating that hydrogen causes a size reduction of the silicon nanocrystals.

  6. Geochemistry of silicon isotopes

    Energy Technology Data Exchange (ETDEWEB)

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

    2018-04-01

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

  7. Status of UA9, the Crystal Collimation Experiment in the SPS

    CERN Document Server

    Scandale, W

    2011-01-01

    UA9 was operated at the CERN-SPS for more than two years to investigate the feasibility of halo collimation with bent crystals. Silicon crystals 2 mm long with bending angles of about 170 μrad were used as primary collimators. The crystal collimation process was steadily achieved through channeling, with high efficiency. The crystal orientation was easily set and optimized with an installed goniometer that has an angular accuracy of about ± 10 μrad. In channeling orientation, the loss rate of the halo particles interacting with the crystal is reduced by half an order of magnitude, whilst the residual off momentum halo escaping from the crystal-collimator area is reduced by a factor two to five. The crystal channeling efficiency of about 75% is reasonably consistent with simulations and with single pass data collected in the extracted proton beam of the SPS North Experimental Area. The accumulated observations, shown in this paper, support our expectation that the coherent deflection of the beam halo by a b...

  8. Raman crystallinity and Hall Effect studies of microcrystalline silicon ...

    African Journals Online (AJOL)

    Aluminium induced crystallization (AIC) was used to crystallize sputtered amorphous silicon thin films on aluminium‐coated glass at annealing temperatures ranging from 250‐520°C in vacuum. Crystalline volume fractions were measured by Raman spectrometry as a function of annealing temperature. It was shown that the ...

  9. Controlling the flow of light with silicon nanostructures

    International Nuclear Information System (INIS)

    Park, W

    2010-01-01

    Silicon is an important material for integrated photonics applications. High refractive index and transparency in the infrared region makes it an ideal platform to implement nanostructures for novel optical devices. We fabricated silicon photonic crystals and experimentally demonstrated negative refraction and self-collimation. We also used heterodyne near-field scanning optical microscope to directly visualize the anomalous wavefronts. When the periodicity is much smaller than wavelength, silicon photonic crystal can be described by the effective medium theory. By engineering effective refractive index with silicon nanorod size, we demonstrated an all-dielectric cloak structure which can hide objects in front of a highly reflecting plane. The work discussed in this review shows the powerful design flexibility and versatility of silicon nanostructures

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

    Science.gov (United States)

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

    1998-01-01

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

  11. Impurities of oxygen in silicon

    International Nuclear Information System (INIS)

    Gomes, V.M.S.

    1985-01-01

    The electronic structure of oxygen complex defects in silicon, using molecular cluster model with saturation by watson sphere into the formalism of Xα multiple scattering method is studied. A systematic study of the simulation of perfect silicon crystal and an analysis of the increasing of atom number in the clusters are done to choose the suitable cluster for the calculations. The divacancy in three charge states (Si:V 2 + , Si:V 2 0 , Si:V 2 - ), of the oxygen pair (Si:O 2 ) and the oxygen-vacancy pair (Si:O.V) neighbours in the silicon lattice, is studied. Distortions for the symmetry were included in the Si:V 2 + and Si:O 2 systems. The behavior of defect levels related to the cluster size of Si:V 2 0 and Si:O 2 systems, the insulated oxygen impurity of silicon in interstitial position (Si:O i ), and the complexes involving four oxygen atoms are analysed. (M.C.K.) [pt

  12. Preliminary Clinical and Pharmacologic Investigation of Photodynamic Therapy with the Silicon Phthalocyanine Photosensitizer Pc 4 for Primary or Metastatic Cutaneous Cancers

    International Nuclear Information System (INIS)

    Kinsella, Timothy James; Baron, Elma D.; Colussi, Valdir C.; Cooper, Kevin D.; Hoppel, Charles L.; Ingalls, Stephen T.; Kenney, Malcolm E.; Li, Xiaolin; Oleinick, Nancy L.; Stevens, Seth R.; Remick, Scot C.

    2011-01-01

    Photodynamic therapy (PDT) for cutaneous malignancies has been found to be an effective treatment with a range of photosensitizers. The phthalocyanine Pc 4 was developed initially for PDT of primary or metastatic cancers in the skin. A Phase I trial was initiated to evaluate the safety and pharmacokinetic profiles of systemically administered Pc 4 followed by red light (Pc 4-PDT) in cutaneous malignancies. A dose-escalation study of Pc 4 (starting dose 0.135 mg/m 2 ) at a fixed light fluence (135 J/cm 2 of 675-nm light) was initiated in patients with primary or metastatic cutaneous malignancies with the aim of establishing the maximum tolerated dose (MTD). Blood samples were taken at intervals over the first 60 h post-PDT for pharmacokinetic analysis, and patients were evaluated for toxicity and tumor response. A total of three patients (two females with breast cancer and one male with cutaneous T-cell lymphoma) were enrolled and treated over the dose range of 0.135 mg/m 2 (first dose level) to 0.54 mg/m 2 (third dose level). Grade 3 erythema within the photoirradiated area was induced in patient 2, and transient tumor regression in patient 3, in spite of the low photosensitizer doses. Pharmacokinetic observations fit a three-compartment exponential elimination model with an initial rapid distribution phase (∼0.2 h) and relatively long terminal elimination phase (∼28 h), Because of restrictive exclusion criteria and resultant poor accrual, the trial was closed before MTD could be reached. While the limited accrual to this initial Phase I study did not establish the MTD nor establish a complete pharmacokinetic and safety profile of intravenous Pc 4-PDT, these preliminary data support further Phase I testing of this new photosensitizer.

  13. Preliminary clinical and pharmacologic investigation of photodynamic therapy with the silicon phthalocyanine photosensitizer Pc 4 for primary or metastatic cutaneous cancers

    Directory of Open Access Journals (Sweden)

    Timothy James Kinsella

    2011-06-01

    Full Text Available Photodynamic therapy (PDT for cutaneous malignancies has been found to be an effective treatment with a range of photosensitizers. The phthalocyanine Pc 4 was developed initially for PDT of primary or metastatic cancers in the skin. A Phase I trial was initiated to evaluate the safety and pharmacokinetic profiles of systemically administered Pc 4 followed by red light (Pc 4-PDT in cutaneous malignancies. A dose-escalation study of Pc 4 (starting dose 0.135 mg/m2 at a fixed light fluence (135 J/cm2 of 675-nm light was initiated in patients with primary or metastatic cutaneous malignancies with the aim of establishing the maximum tolerated dose (MTD. Blood samples were taken at intervals over the first 60 hours post-PDT for pharmacokinetic analysis, and patients were evaluated for toxicity and tumor response. A total of 3 patients (2 females with breast cancer and 1 male with cutaneous lymphoma were enrolled and treated over the dose range of 0.135 mg/m2 (first dose level to 0.54 mg/m2 (third dose level. Grade 3 erythema within the photoirradiated area was induced in patient 2, and transient tumor regression in patient 3, in spite of the low photosensitizer doses. Pharmacokinetic observations fit a 3-compartment exponential elimination model with an initial rapid distribution phase (~0.2 hrs and relatively long terminal elimination phase (~28 hrs, Because of restrictive exclusion criteria and resultant poor accrual, the trial was closed before MTD could be reached. While the limited accrual to this initial Phase I study did not establish the MTD nor establish a complete pharmacokinetic and safety profile of intravenous Pc 4-PDT, these preliminary data support further Phase I testing of this new photosensitizer.

  14. Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

    Science.gov (United States)

    Bolzoni, Leandro; Xia, Mingxu; Babu, Nadendla Hari

    2016-01-01

    The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles. PMID:28008967

  15. Femtosecond laser irradiation-induced infrared absorption on silicon surfaces

    Directory of Open Access Journals (Sweden)

    Qinghua Zhu

    2015-04-01

    Full Text Available The near-infrared (NIR absorption below band gap energy of crystalline silicon is significantly increased after the silicon is irradiated with femtosecond laser pulses at a simple experimental condition. The absorption increase in the NIR range primarily depends on the femtosecond laser pulse energy, pulse number, and pulse duration. The Raman spectroscopy analysis shows that after the laser irradiation, the silicon surface consists of silicon nanostructure and amorphous silicon. The femtosecond laser irradiation leads to the formation of a composite of nanocrystalline, amorphous, and the crystal silicon substrate surface with microstructures. The composite has an optical absorption enhancement at visible wavelengths as well as at NIR wavelength. The composite may be useful for an NIR detector, for example, for gas sensing because of its large surface area.

  16. Effect of neutron irradiation on p-type silicon

    International Nuclear Information System (INIS)

    Sopko, B.

    1973-01-01

    The possibilities are discussed of silicon isotope reactions with neutrons of all energies. In the reactions, 30 Si is converted to a stable phosphorus isotope forming n-type impurities in silicon. The above reactions proceed as a result of thermal neutron irradiation. An experiment is reported involving irradiation of two p-type silicon single crystals having a specific resistance of 2000 ohm.cm and 5000 to 20 000 ohm.cm, respectively, which changed as a result of irradiation into n-type silicon with a given specific resistance. The specific resistance may be pre-calculated from the concentration of impurities and the time of irradiation. The effects of irradiation on other silicon parameters and thus on the suitability of silicon for the manufacture of semiconductor elements are discussed. (J.K.)

  17. LSA Large Area Silicon Sheet Task. Continuous Liquid Feed Czochralski Growth. [for solar cell fabrication

    Science.gov (United States)

    Fiegl, G.

    1979-01-01

    The design and development of equipment and processes to demonstrate continuous growth of crystals by the Czochralski method suitable for producing single silicon crystals for use in solar cells is presented. The growth of at least 150 kg of mono silicon crystal, 150 mm in diameter is continuous from one growth container. A furnace with continuous liquid replenishment of the growth crucible, accomplished by a meltdown system with a continuous solid silicon feed mechanism and a liquid transfer system, with associated automatic feedback controls is discussed. Due to the silicon monoxide build up in the furnace and its retarding effect on crystal growth the furnace conversion for operation in the low pressure range is described. Development of systems for continuous solid recharging of the meltdown chamber for various forms of poly silicon is described.

  18. Naturally occurring 32 Si and low-background silicon dark matter detectors

    Energy Technology Data Exchange (ETDEWEB)

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

    2018-05-01

    The naturally occurring radioisotope Si-32 represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of Si-32 and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the Si-32 concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon “ore” and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of Si-32-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in Si-32. To quantitatively evaluate the Si-32 content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon-based detectors with low levels of Si-32, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.

  19. Naturally occurring 32Si and low-background silicon dark matter detectors

    Science.gov (United States)

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

    2018-05-01

    The naturally occurring radioisotope 32Si represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of 32Si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the 32Si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon "ore" and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of 32Si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32Si. To quantitatively evaluate the 32Si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon detectors with low levels of 32Si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.

  20. Separation of primary solid phases from Al-Si alloy melts

    Directory of Open Access Journals (Sweden)

    Ki Young Kim

    2014-07-01

    Full Text Available The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical, physical and chemical properties of the alloys should be removed. On the other hand, Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process. One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts. This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation, draining, filtration, electromagnetic separation and centrifugal separation, focused on the iron removal and on the separation of silicon in the solvent refining process.

  1. Development of an autoclave with zirconia crystal windows for in-situ observation of sample surface under primary water conditions of pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Fukumura, Takuya; Totsuka, Nobuo; Arioka, Koji [Inst. of Nuclear Safety System Inc., Mihama, Fukui (Japan); Nakajima, Nobuo

    2002-09-01

    Elucidating the mechanism for primary water stress corrosion cracking (PWSCC) is important for improving the reliability of structural materials in the primary system of pressurized water reactors (PWR). For this purpose, visualization of corrosion material surface in the primary coolant environment is effective, but it was impossible because of lack of suitable window material. Yttria stabilized zirconia was newly selected as a candidate for in-situ window material in the primary coolant environment of PWR. Its sufficient corrosion resistance was proved by measuring the transmissivity of light after being immersed in the primary coolant environment. A new autoclave with two windows of yttria-stabilized zirconia was developed. The corrosion material surfaces of Alloy600 and SUS304 in the primary coolant environment were clearly observed with this autoclave. Observations of cracks generated on the surface of SUS304 specimen, suggest that its generation time depends on temperature. (author)

  2. Porous silicon technology for integrated microsystems

    Science.gov (United States)

    Wallner, Jin Zheng

    With the development of micro systems, there is an increasing demand for integrable porous materials. In addition to those conventional applications, such as filtration, wicking, and insulating, many new micro devices, including micro reactors, sensors, actuators, and optical components, can benefit from porous materials. Conventional porous materials, such as ceramics and polymers, however, cannot meet the challenges posed by micro systems, due to their incompatibility with standard micro-fabrication processes. In an effort to produce porous materials that can be used in micro systems, porous silicon (PS) generated by anodization of single crystalline silicon has been investigated. In this work, the PS formation process has been extensively studied and characterized as a function of substrate type, crystal orientation, doping concentration, current density and surfactant concentration and type. Anodization conditions have been optimized for producing very thick porous silicon layers with uniform pore size, and for obtaining ideal pore morphologies. Three different types of porous silicon materials: meso porous silicon, macro porous silicon with straight pores, and macro porous silicon with tortuous pores, have been successfully produced. Regular pore arrays with controllable pore size in the range of 2mum to 6mum have been demonstrated as well. Localized PS formation has been achieved by using oxide/nitride/polysilicon stack as masking materials, which can withstand anodization in hydrofluoric acid up to twenty hours. A special etching cell with electrolytic liquid backside contact along with two process flows has been developed to enable the fabrication of thick macro porous silicon membranes with though wafer pores. For device assembly, Si-Au and In-Au bonding technologies have been developed. Very low bonding temperature (˜200°C) and thick/soft bonding layers (˜6mum) have been achieved by In-Au bonding technology, which is able to compensate the potentially

  3. Low cost silicon solar array project large area silicon sheet task: Silicon web process development

    Science.gov (United States)

    Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.; Blais, P. D.; Davis, J. R., Jr.

    1977-01-01

    Growth configurations were developed which produced crystals having low residual stress levels. The properties of a 106 mm diameter round crucible were evaluated and it was found that this design had greatly enhanced temperature fluctuations arising from convection in the melt. Thermal modeling efforts were directed to developing finite element models of the 106 mm round crucible and an elongated susceptor/crucible configuration. Also, the thermal model for the heat loss modes from the dendritic web was examined for guidance in reducing the thermal stress in the web. An economic analysis was prepared to evaluate the silicon web process in relation to price goals.

  4. A versatile Czochralski crystal growth system with automatic diameter control

    Science.gov (United States)

    Aggarwal, M. D.; Metzl, R.; Wang, W. S.; Choi, J.

    1995-07-01

    A versatile Czochralski crystal pulling system with automatic diameter control for the growth of nonlinear optical oxide crystals is discussed. Pure and doped bulk single crystals of bismuth silicon oxide (Bi12SiO20) have been successfully grown using this system. The system consists of a regular Czochralski type pulling system with provision for continuous weighing of the growing crystal to provide feedback for power control.

  5. Protein crystals as scanned probes for recognition atomic force microscopy.

    Science.gov (United States)

    Wickremasinghe, Nissanka S; Hafner, Jason H

    2005-12-01

    Lysozyme crystal growth has been localized at the tip of a conventional silicon nitride cantilever through seeded nucleation. After cross-linking with glutaraldehyde, lysozyme protein crystal tips image gold nanoparticles and grating standards with a resolution comparable to that of conventional tips. Force spectra between the lysozyme crystal tips and surfaces covered with antilysozyme reveal an adhesion force that drops significantly upon blocking with free lysozyme, thus confirming that lysozyme crystal tips can detect molecular recognition interactions.

  6. Microdefects in neutron-transmutationaly doped silicon

    International Nuclear Information System (INIS)

    Vysotskaya, V.V.; Gorin, S.N.; Gres'kov, I.M.; Sobolev, N.A.; Shek, E.I.

    1988-01-01

    Using the method of X-ray topography and high-voltage electron microscopy, the nature of microdefects and character of their changes in neutron-transmutationaly doped silicon depending on the sample prehistory and heat treatment (HT) conditions are refined. It is shown that the microstructure of neutron-transmutationaly doped dislocation-free silicon crystals depends on conditions of ingot growth and post-radiation annealing environment. Annealing in chlorine-containing atmosphere removes microdefects (MD), although in vacuum, argon or air growing MD are preserved and new MD are formed

  7. Microdefects in neutron-transmutationaly doped silicon

    Energy Technology Data Exchange (ETDEWEB)

    Vysotskaya, V V; Gorin, S N; Gres' kov, I M; Sobolev, N A; Shek, E I

    1988-03-01

    Using the method of X-ray topography and high-voltage electron microscopy, the nature of microdefects and character of their changes in neutron-transmutationaly doped silicon depending on the sample prehistory and heat treatment (HT) conditions are refined. It is shown that the microstructure of neutron-transmutationaly doped dislocation-free silicon crystals depends on conditions of ingot growth and post-radiation annealing environment. Annealing in chlorine-containing atmosphere removes microdefects (MD), although in vacuum, argon or air growing MD are preserved and new MD are formed.

  8. Investigation of beam effect on porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kotai, E. E-mail: kotai@rmki.kfki.hu; Paszti, F.; Szilagyi, E

    2000-03-01

    When performing Rutherford Backscattering Spectroscopy (RBS) measurements combined with channeling on 'columnar' porous silicon (PS) samples with beam aligned to the direction of the pores, a strong beam effect was observed. The minimum yield as a function of the beam dose for different porous samples was compared with the yield measured on single crystal silicon. It was demonstrated that the beam effect strongly depends on the porosity of the sample. Bombardment in the random direction caused about 10% higher change in the minimum yield than in the channel direction.

  9. Investigation of beam effect on porous silicon

    International Nuclear Information System (INIS)

    Kotai, E.; Paszti, F.; Szilagyi, E.

    2000-01-01

    When performing Rutherford Backscattering Spectroscopy (RBS) measurements combined with channeling on 'columnar' porous silicon (PS) samples with beam aligned to the direction of the pores, a strong beam effect was observed. The minimum yield as a function of the beam dose for different porous samples was compared with the yield measured on single crystal silicon. It was demonstrated that the beam effect strongly depends on the porosity of the sample. Bombardment in the random direction caused about 10% higher change in the minimum yield than in the channel direction

  10. Electrical Properties Of Amorphous Selenium (aSe)/p-Type Silicon ...

    African Journals Online (AJOL)

    aSe) on four chemically etched p-type silicon crystals (pSi) each of 5Ω-cm resistivity and carrier concentration of 2.8x1015cm-3. Two of the pSi crystals have surface orientation of (111) while the other two crystals have (100) surface orientation.

  11. UA9 Results from Crystal Collimation Tests in the SPS & Future Strategy

    CERN Document Server

    Scandale, W

    2013-01-01

    The UA9 Collaboration, with support by EuCARD-AccNet, is investigating how bent crystals, used as primary collimators, could assist and improve the collimation process in modern hadron colliders like the LHC. From 2009 onwards the UA9 Collaboration has successfully tested silicon crystals at the SPS, performing measurements of the associated collimation efficiency by means of various methods and detectors. This report presents the main UA9 results, obtained with protons and Pb ions at 120 GeV/c and 270 GeV/c per charge from 2009 to 2012, which indicate that crystal assisted collimation is well mastered and understood. Specifically, reduced loss rates were demonstrated close to the crystal, as well as in a downstream off-momentum region, and, indeed, all around the ring. In addition, the importance of the crystal miscut angle was elucidated and a first industrial goniometer compliant with LHC specifications has become available. At the end of the report, the near-term plan for LHC crystal collimation is descri...

  12. Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

    CERN Document Server

    Gentile, C A; Hartfield, J W; Hawryluk, R J; Hegeler, F; Heitzenroeder, P J; Jun, C H; Ku, L P; Lamarche, P H; Myers, M C; Parker, J J; Parsells, R F; Payen, M; Raftopoulos, S; Sethian, J D

    2002-01-01

    The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W centre dot cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated w...

  13. Generation and manipulation of entangled photons on silicon chips

    Directory of Open Access Journals (Sweden)

    Matsuda Nobuyuki

    2016-08-01

    Full Text Available Integrated quantum photonics is now seen as one of the promising approaches to realize scalable quantum information systems. With optical waveguides based on silicon photonics technologies, we can realize quantum optical circuits with a higher degree of integration than with silica waveguides. In addition, thanks to the large nonlinearity observed in silicon nanophotonic waveguides, we can implement active components such as entangled photon sources on a chip. In this paper, we report recent progress in integrated quantum photonic circuits based on silicon photonics. We review our work on correlated and entangled photon-pair sources on silicon chips, using nanoscale silicon waveguides and silicon photonic crystal waveguides. We also describe an on-chip quantum buffer realized using the slow-light effect in a silicon photonic crystal waveguide. As an approach to combine the merits of different waveguide platforms, a hybrid quantum circuit that integrates a silicon-based photon-pair source and a silica-based arrayed waveguide grating is also presented.

  14. Slit and phase grating diffraction with a double crystal diffractometer

    International Nuclear Information System (INIS)

    Treimer, Wolfgang; Hilger, Andre; Strobl, Markus

    2006-01-01

    The lateral coherence properties of a neutron beam (λ=0.5248nm) in a double crystal diffractometer (DCD) were studied by means of single slit diffraction and by diffraction by different perfect Silicon phase gratings. Perfect agreements were found for the lateral coherence length measured with the slit and for the one determined by Silicon phase gratings, however, some peculiarities are still present

  15. Strontium zirconate as silicon and aluminum scavenger in yttria stabilized zirconia

    DEFF Research Database (Denmark)

    Andersen, Thomas; Hansen, Karin Vels; Chorkendorff, Ib

    2011-01-01

    Here we report on strontium zirconate as a getter for silicon dioxide and aluminum oxide in yttria stabilized zirconia (YSZ) single crystals for cleaning purposes. YSZ single crystals were covered with strontium zirconate powder and heat treated at 1450°C in water vapor. After treatment the YSZ...... by transmission electron microscopy (TEM) the interface region between bump and YSZ single crystal bulk was examined. EDS showed a homogeneous distribution of silicon and aluminum through the cross section of a bump. The results suggest strontium zirconate as a good getter for silicon and aluminum from bulk...

  16. Photonic crystal waveguides in PECVD glass

    DEFF Research Database (Denmark)

    Liu, Haoling; Frandsen, Lars Hagedorn; Têtu, Amélie

    Silicon oxynitride (SiON) on silicon has found wide use as a robust and versatileplatform for integrated, optical devices. With plasma-enhanced chemical vapourdeposition (PECVD) the refractive index can be varied all the way from 1.5 (pure silica,SiO2) to 2.0 (pure silicon nitride, Si3N4). We have...... fabricated glasses with refractive indexup to approximately 1.75, with which value it is possible to fabricate photonic crystalwaveguides. These structures have the advantage of being transparent in the whole of thevisible region, which makes them different from photonic crystals made...

  17. Crystals in crystals

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Schmidt, I.; Carlsson, A.

    2005-01-01

    A major factor governing the performance of catalytically active particles supported on a zeolite carrier is the degree of dispersion. It is shown that the introduction of noncrystallographic mesopores into zeolite single crystals (silicalite-1, ZSM-5) may increase the degree of particle dispersion....... As representative examples, a metal (Pt), an alloy (PtSn), and a metal carbide (beta-Mo2C) were supported on conventional and mesoporous zeolite carriers, respectively, and the degree of particle dispersion was compared by TEM imaging. On conventional zeolites, the supported material aggregated on the outer surface...

  18. Optimization of chemical displacement deposition of copper on porous silicon.

    Science.gov (United States)

    Bandarenka, Hanna; Redko, Sergey; Nenzi, Paolo; Balucani, Marco; Bondarenko, Vitaly

    2012-11-01

    Copper (II) sulfate was used as a source of copper to achieve uniform distribution of Cu particles deposited on porous silicon. Layers of the porous silicon were formed by electrochemical anodization of Si wafers in a mixture of HF, C3H7OH and deionized water. The well-known chemical displacement technique was modified to grow the copper particles of specific sizes. SEM and XRD analysis revealed that the outer surface of the porous silicon was covered with copper particles of the crystal orientation inherited from the planes of porous silicon skeleton. The copper crystals were found to have the cubic face centering elementary cell. In addition, the traces of Cu2O cubic primitive crystalline phases were identified. The dimensions of Cu particles were determined by the Feret's analysis of the SEM images. The sizes of the particles varied widely from a few to hundreds of nanometers. A phenomenological model of copper deposition was proposed.

  19. Virtual Crystallizer

    Energy Technology Data Exchange (ETDEWEB)

    Land, T A; Dylla-Spears, R; Thorsness, C B

    2006-08-29

    Large dihydrogen phosphate (KDP) crystals are grown in large crystallizers to provide raw material for the manufacture of optical components for large laser systems. It is a challenge to grow crystal with sufficient mass and geometric properties to allow large optical plates to be cut from them. In addition, KDP has long been the canonical solution crystal for study of growth processes. To assist in the production of the crystals and the understanding of crystal growth phenomena, analysis of growth habits of large KDP crystals has been studied, small scale kinetic experiments have been performed, mass transfer rates in model systems have been measured, and computational-fluid-mechanics tools have been used to develop an engineering model of the crystal growth process. The model has been tested by looking at its ability to simulate the growth of nine KDP boules that all weighed more than 200 kg.

  20. single crystals

    Indian Academy of Sciences (India)

    2018-05-18

    May 18, 2018 ... Abstract. 4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical ... studies on the proper growth, linear and nonlinear optical ..... between the optic axes and optic sign of the biaxial crystal.