Sample records for bismuth silicon oxide

  1. Transient response of photorefractive bismuth silicon oxide in the pulsed regime

    Microsoft Academic Search

    D. C. Jones; L. Solymar

    1991-01-01

    The transient response of bismuth silicon oxide in the regime, pulsed exposure time <<<< carrier recombination time, is modelled using the linearized band transport equations. The theory predicts a rapid build-up of photorefractive grating on a nanosecond time scale with response time inversely proportional to exposure. The build-up is followed by a decline in grating strength to a finite final

  2. Surface-charge measurements in microgap dielectric barrier discharge using bismuth silicon oxide crystals

    NASA Astrophysics Data System (ADS)

    Mukaigawa, S.; Matsuda, H.; Fue, H.; Takahashi, R.; Takaki, K.; Fujiwara, T.

    2013-06-01

    A surface-charge measurement system based on the Pockels effect in bismuth silicon oxide dielectric crystals was constructed for measuring the surface-charge density of the dielectrics in the microgap dielectric barrier discharge. We re-examined the calculation methods of the surface-charge density from the voltage applied to the BSO crystal, obtained by laser interferometry. The charge calculated using the circuit equation coincided with the that obtained using the discharge current. Under certain experimental conditions, the maximum values of the surface charge density in the discharge cell with and without a protection glass were +2.0 and +2.5 nC/cm2, respectively.

  3. Electrical activation and electron spin resonance measurements of implanted bismuth in isotopically enriched silicon-28

    NASA Astrophysics Data System (ADS)

    Weis, C. D.; Lo, C. C.; Lang, V.; Tyryshkin, A. M.; George, R. E.; Yu, K. M.; Bokor, J.; Lyon, S. A.; Morton, J. J. L.; Schenkel, T.

    2012-04-01

    We have performed continuous wave and pulsed electron spin resonance measurements of implanted bismuth donors in isotopically enriched silicon-28. Donors are electrically activated via thermal annealing with minimal diffusion. Damage from bismuth ion implantation is repaired during thermal annealing as evidenced by narrow spin resonance linewidths (Bpp=12?T) and long spin coherence times (T2=0.7 ms, at temperature T =8 K). The results qualify ion implanted bismuth as a promising candidate for spin qubit integration in silicon.

  4. Optical and electrical properties of thermally oxidized bismuth thin films

    NASA Astrophysics Data System (ADS)

    Condurache-Bota, S.; Tigau, N.; Rambu, A. P.; Rusu, G. G.; Rusu, G. I.

    2011-10-01

    Bismuth trioxide (Bi 2O 3) thin films were prepared by dry thermal oxidation of metallic bismuth films deposited by vacuum evaporation. The oxidation process of Bi films consists of a heating from the room temperature to an oxidation temperature ( To = 673 K), with a temperature rate of 8 K/min; an annealing for 1 h at oxidation temperature and, finally, a cooling to room temperature. The optical transmission and reflection spectra of the films were studied in spectral domains ranged between 300 nm and 1700 nm, for the transmission coefficient, and between 380 nm and 1050 nm for the reflection coefficient, respectively. The thin-film surface structures of the metal/oxide/metal type were used for the study of the static current-voltage ( I- U) characteristics. The temperature of the substrate during bismuth deposition strongly influences both the optical and the electrical properties of the oxidized films. For lower values of intensity of electric field ( ? < 5 × 10 4V/cm), I- U characteristics are ohmic.

  5. [Efficient oxidative degradation of tetrabromobisphenol a by silver bismuth oxide].

    PubMed

    Chen, Man-tang; Song, Zhou; Wang, Nan; Ding, Yao-bin; Liao, Hai-xing; Zhu, Li-hua

    2015-01-01

    Silver bismuth oxide(BSO) was prepared by a simple ion exchange-coprecipitation method with AgNO3 and NaBiO, .2H2O as raw materials, and then used to oxidatively degrade tetrabromobisphenol A(TBBPA). Effects of the molar ratio of Ag/Bi during BSO preparation and the BSO dosage on the degradation of TBBPA were investigated. The results showed that under the optimized conditions (i.e., the Ag/Bi molar ratio of 1:1, BSO dosage of 1 g x L(-1), 40 mg x L(-1) of TBBPA was completely degraded and the removal of total organic carbon achieved more than 80% within 7 min. The degradation intermediates of TBBPA were identified by ion chromatography, gas chromatograph-mass spectrometer and X-ray photoelectron spectroscopy. The degradation pathway of TBBPA included the debromination, the cleavage of tert-butyl group and the open epoxidation of benzene ring. Based on a quenching study of NaN3, singlet oxygen was proved to play a dominant role in the TBBPA degradation. PMID:25898666

  6. Bismuth oxide nonlinear fiber-based optical devices for telecommunications

    NASA Astrophysics Data System (ADS)

    Lee, Ju Han

    2006-09-01

    The optical fiber fabrication technology based on Bismuth oxide (Bi IIO 3) material has advanced significantly in recent years and has resulted in the production of a variety of high quality of Bi IIO 3 based optical fibers: for example, rare-earth doped Bi IIO 3 fibers and highly nonlinear Bi IIO 3 fibers (Bi-NLF). One of the most striking and attractive possibilities offered by the Bi IIO 3 based optical fibers is the opportunity to implement a range of nonlinear optical signal processing devices with only a meter or less length of the fiber due to its ultra-high material nonlinear coefficient, which is 100 times higher than that of silica. The state-of-the-art Bismuth Oxide based nonlinear optical fiber technology for nonlinear optical signal processing devices is reviewed from a viewpoint of possible application for telecommunications.

  7. Bismuth oxide nanotubes-graphene fiber-based flexible supercapacitors.

    PubMed

    Gopalsamy, Karthikeyan; Xu, Zhen; Zheng, Bingna; Huang, Tieqi; Kou, Liang; Zhao, Xiaoli; Gao, Chao

    2014-08-01

    Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm(-2) (for a single electrode) and 17.3 mF cm(-2) (for the whole device) at 0.1 mA cm(-2), respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics. PMID:24975864

  8. Oxidation resistance of silicon ceramics

    NASA Technical Reports Server (NTRS)

    Yasutoshi, H.; Hirota, K.

    1984-01-01

    Oxidation resistance, and examples of oxidation of SiC, Si3N4 and sialon are reviewed. A description is given of the oxidation mechanism, including the oxidation product, oxidation reaction and the bubble size. The oxidation reactions are represented graphically. An assessment is made of the oxidation process, and an oxidation example of silicon ceramics is given.

  9. Mechanism of Selective Oxidation of Propene to Acrolein on Bismuth Molybdates from Quantum Mechanical Calculations

    E-print Network

    Goddard III, William A.

    Mechanism of Selective Oxidation of Propene to Acrolein on Bismuth Molybdates from Quantum for understanding the fundamental chemical mechanisms underlying the selective oxidation of propene to acrolein to form acrolein, and acrolein desorption. The formation of -allyl intermediate is reversible

  10. Bismuth Oxide Nanoparticles in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.; Mackinnon, Ian D. R.

    1997-01-01

    Platey grains of cubic Bi2O3, alpha-Bi2O3, and Bi2O(2.75), nanograins were associated with chondritic porous interplanetary dust particles W7029C1, W7029E5, and 2011C2 that were collected in the stratosphere at 17-19 km altitude. Similar Bi oxide nanograins were present in the upper stratosphere during May 1985. These grains are linked to the plumes of several major volcanic eruptions during the early 1980s that injected material into the stratosphere. The mass of sulfur from these eruptions is a proxy for the mass of stratospheric Bi from which we derive the particle number densities (p/cu m) for "average Bi2O3 nanograins" due to this volcanic activity and those necessary to contaminate the extraterrestrial chondritic porous interplanetary dust particles via collisional sticking. The match between both values supports the idea that Bi2O3 nanograins of volcanic origin could contaminate interplanetary dust particles in the Earth's stratosphere.

  11. Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides

    SciTech Connect

    Leitner, J., E-mail: Jindrich.Leitner@vscht.c [Department of Solid State Engineering, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Jakes, V.; Sofer, Z.; Sedmidubsky, D. [Department of Inorganic Chemistry, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Ruzicka, K. [Department of Physical Chemistry, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Svoboda, P. [Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic)

    2011-02-15

    Heat capacity and enthalpy increments of ternary bismuth tantalum oxides Bi{sub 4}Ta{sub 2}O{sub 11}, Bi{sub 7}Ta{sub 3}O{sub 18} and Bi{sub 3}TaO{sub 7} were measured by the relaxation time method (2-280 K), DSC (265-353 K) and drop calorimetry (622-1322 K). Temperature dependencies of the molar heat capacity in the form C{sub pm}=445.8+0.005451T-7.489x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1}, C{sub pm}=699.0+0.05276T-9.956x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1} and C{sub pm}=251.6+0.06705T-3.237x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1} for Bi{sub 3}TaO{sub 7}, Bi{sub 4}Ta{sub 2}O{sub 11} and for Bi{sub 7}Ta{sub 3}O{sub 18}, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S{sup o}{sub m}(298.15 K)=449.6{+-}2.3 J K{sup -1} mol{sup -1} for Bi{sub 4}Ta{sub 2}O{sub 11}, S{sup o}{sub m}(298.15 K)=743.0{+-}3.8 J K{sup -1} mol{sup -1} for Bi{sub 7}Ta{sub 3}O{sub 18} and S{sup o}{sub m}(298.15 K)=304.3{+-}1.6 J K{sup -1} mol{sup -1} for Bi{sub 3}TaO{sub 7}, were evaluated from the low-temperature heat capacity measurements. -- Graphical Abstract: Temperature dependence of {Delta}{sub ox}C{sub pm} for bismuth tantalum mixed oxides. Display Omitted Research highlights: > Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides Bi{sub 4}Ta{sub 2}O{sub 11}, Bi{sub 7}Ta{sub 3}O{sub 18} and Bi{sub 3}TaO{sub 7}. > Heat capacity by DSC calorimetry and heat-pulsed calorimetry. > Enthalpy increments by drop calorimetry. > Einstein-Debye model for low-temperature dependence of the heat capacity. > Application of Neumann-Kopp rule.

  12. Tributylphosphate Extraction Behavior of Bismuthate-Oxidized Americium

    SciTech Connect

    Mincher; Leigh R. Martin; Nicholas C. Schmitt

    2008-08-01

    Higher oxidation states of americium have long been known; however, options for their preparation in acidic solution are limited. The conventional choice, silver-catalyzed peroxydisulfate, is not useful at nitric acid concentrations above about 0.3 M. We investigated the use of sodium bismuthate as an oxidant for Am3+ in acidic solution. Room-temperature oxidation produced AmO2 2+ quantitatively, whereas oxidation at 80 °C produced AmO2+ quantitatively. The efficacy of the method for the production of oxidized americium was verified by fluoride precipitation and by spectroscopic absorbance measurements. We performed absorbance measurements using a conventional 1 cm cell for high americium concentrations and a 100 cm liquid waveguide capillary cell for low americium concentrations. Extinction coefficients for the absorbance of Am3+ at 503 nm, AmO2+ at 514 nm, and AmO2 2+ at 666 nm in 0.1 M nitric acid are reported. We also performed solvent extraction experiments with the hexavalent americium using the common actinide extraction ligand tributyl phosphate (TBP) for comparison to the other hexavalent actinides. Contact with 30% tributyl phosphate in dodecane reduced americium; it was nevertheless extracted using short contact times. The TBP extraction of AmO2 2+ over a range of nitric acid concentrations is shown for the first time and was found to be analogous to that of uranyl, neptunyl, and plutonyl ions.

  13. Stabilization of elusive silicon oxides

    NASA Astrophysics Data System (ADS)

    Wang, Yuzhong; Chen, Mingwei; Xie, Yaoming; Wei, Pingrong; Schaefer, Henry F.; Schleyer, Paul Von R.; Robinson, Gregory H.

    2015-06-01

    Molecular SiO2 and other simple silicon oxides have remained elusive despite the indispensable use of silicon dioxide materials in advanced electronic devices. Owing to the great reactivity of silicon–oxygen double bonds, as well as the low oxidation state of silicon atoms, the chemistry of simple silicon oxides is essentially unknown. We now report that the soluble disilicon compound, L:Si=Si:L (where L:?=?:C{N(2,6-iPr2C6H3)CH}2), can be directly oxidized by N2O and O2 to give the carbene-stabilized Si2O3 and Si2O4 moieties, respectively. The nature of the silicon oxide units in these compounds is probed by spectroscopic methods, complementary computations and single-crystal X-ray diffraction.

  14. Bismuth oxide aqueous colloidal nanoparticles inhibit Candida albicans growth and biofilm formation

    PubMed Central

    Hernandez-Delgadillo, Rene; Velasco-Arias, Donaji; Martinez-Sanmiguel, Juan Jose; Diaz, David; Zumeta-Dube, Inti; Arevalo-Niño, Katiushka; Cabral-Romero, Claudio

    2013-01-01

    Multiresistance among microorganisms to common antimicrobials has become one of the most significant concerns in modern medicine. Nanomaterials are a new alternative to successfully treat the multiresistant microorganisms. Nanostructured materials are used in many fields, including biological sciences and medicine. Recently, it was demonstrated that the bactericidal activity of zero-valent bismuth colloidal nanoparticles inhibited the growth of Streptococcus mutans; however the antimycotic potential of bismuth nanostructured derivatives has not yet been studied. The main objective of this investigation was to analyze the fungicidal activity of bismuth oxide nanoparticles against Candida albicans, and their antibiofilm capabilities. Our results showed that aqueous colloidal bismuth oxide nanoparticles displayed antimicrobial activity against C. albicans growth (reducing colony size by 85%) and a complete inhibition of biofilm formation. These results are better than those obtained with chlorhexidine, nystatin, and terbinafine, the most effective oral antiseptic and commercial antifungal agents. In this work, we also compared the antimycotic activities of bulk bismuth oxide and bismuth nitrate, the precursor metallic salt. These results suggest that bismuth oxide colloidal nanoparticles could be a very interesting candidate as a fungicidal agent to be incorporated into an oral antiseptic. Additionally, we determined the minimum inhibitory concentration for the synthesized aqueous colloidal Bi2O3 nanoparticles. PMID:23637533

  15. Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications.

    PubMed

    Saeedi, K; Szech, M; Dluhy, P; Salvail, J Z; Morse, K J; Riemann, H; Abrosimov, N V; Nötzel, N; Litvinenko, K L; Murdin, B N; Thewalt, M L W

    2015-01-01

    The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched (28)Si. PMID:25990870

  16. Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications

    PubMed Central

    Saeedi, K.; Szech, M.; Dluhy, P.; Salvail, J.Z.; Morse, K.J.; Riemann, H.; Abrosimov, N.V.; Nötzel, N.; Litvinenko, K.L.; Murdin, B.N.; Thewalt, M.L.W.

    2015-01-01

    The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched 28Si. PMID:25990870

  17. Multifunctional multilayer films containing polyoxometalates and bismuth oxide nanoparticles.

    PubMed

    Li, Chunxiang; O'Halloran, Kevin P; Ma, Huiyuan; Shi, Shilin

    2009-06-11

    Multifunctional multilayer films consisting of the Keggin-type polyoxometalate [SiW(9)V(3)O(40)](7-) (SiW(9)V(3)) and bismuth oxide nanoparticles (Bi(2)O(3)) were prepared by the layer-by-layer assembly method. For the first time, electrochromic and photochromic studies were done on a film containing both polyoxometalates and nanoparticles. The films were characterized by UV-vis absorption, emission spectra, and atomic force microscopy. Their electrochromic and photochromic properties were investigated by cyclic voltammetry and UV-vis spectroscopy. The results show that the reduction of SiW(9)V(3) is very reversible and tunable with the addition of Bi(2)O(3) layers into the film. The electrocatalytic activity of the films toward oxidation of l-cysteine hydrochloride hydrate (l-cysteine) and reduction of nitrite were studied with cyclic voltammetry. The results show that the incorporation of Bi(2)O(3) nanoparticles into the films changed the films' photoluminescence properties and electrocatalytic efficiency. PMID:19449851

  18. Structure and resistivity of bismuth nanobelts in situ synthesized on silicon wafer through an ethanol-thermal method

    SciTech Connect

    Gao Zheng; Qin Haiming; Yan Tao [State Key Laboratory of Crystal Materials, Bio-Micro/Nano Functional Materials Center, Shandong University, Jinan 250100 (China); Liu Hong, E-mail: hongliu@sdu.edu.cn [State Key Laboratory of Crystal Materials, Bio-Micro/Nano Functional Materials Center, Shandong University, Jinan 250100 (China); Wang Jiyang [State Key Laboratory of Crystal Materials, Bio-Micro/Nano Functional Materials Center, Shandong University, Jinan 250100 (China)

    2011-12-15

    Bismuth nanobelts in situ grown on a silicon wafer were synthesized through an ethanol-thermal method without any capping agent. The structure of the bismuth belt-silicon composite nanostructure was characterized by scanning electron microscope, energy-dispersive X-ray spectroscopy, and high resolution transmission electron microscope. The nanobelt is a multilayered structure 100-800 nm in width and over 50 {mu}m in length. One layer has a thickness of about 50 nm. A unique sword-like nanostructure is observed as the initial structure of the nanobelts. From these observations, a possible growth mechanism of the nanobelt is proposed. Current-voltage property measurements indicate that the resistivity of the nanobelts is slightly larger than that of the bulk bismuth material. - Graphical Abstract: TEM images, EDS, and electron diffraction pattern of bismuth nanobelts. Highlights: Black-Right-Pointing-Pointer Bismuth nanobelts in situ grown on silicon wafer were achieved. Black-Right-Pointing-Pointer Special bismuth-silicon nanostructure. Black-Right-Pointing-Pointer Potential application in sensitive magnetic sensor and other electronic devices.

  19. Nanoporous silicon oxide memory.

    PubMed

    Wang, Gunuk; Yang, Yang; Lee, Jae-Hwang; Abramova, Vera; Fei, Huilong; Ruan, Gedeng; Thomas, Edwin L; Tour, James M

    2014-08-13

    Oxide-based two-terminal resistive random access memory (RRAM) is considered one of the most promising candidates for next-generation nonvolatile memory. We introduce here a new RRAM memory structure employing a nanoporous (NP) silicon oxide (SiOx) material which enables unipolar switching through its internal vertical nanogap. Through the control of the stochastic filament formation at low voltage, the NP SiOx memory exhibited an extremely low electroforming voltage (? 1.6 V) and outstanding performance metrics. These include multibit storage ability (up to 9-bits), a high ON-OFF ratio (up to 10(7) A), a long high-temperature lifetime (? 10(4) s at 100 °C), excellent cycling endurance (? 10(5)), sub-50 ns switching speeds, and low power consumption (? 6 × 10(-5) W/bit). Also provided is the room temperature processability for versatile fabrication without any compliance current being needed during electroforming or switching operations. Taken together, these metrics in NP SiOx RRAM provide a route toward easily accessed nonvolatile memory applications. PMID:24992278

  20. Investigation of solution-processed bismuth-niobium-oxide films

    NASA Astrophysics Data System (ADS)

    Inoue, Satoshi; Ariga, Tomoki; Matsumoto, Shin; Onoue, Masatoshi; Miyasako, Takaaki; Tokumitsu, Eisuke; Chinone, Norimichi; Cho, Yasuo; Shimoda, Tatsuya

    2014-10-01

    The characteristics of bismuth-niobium-oxide (BNO) films prepared using a solution process were investigated. The BNO film annealed at 550 °C involving three phases: an amorphous phase, Bi3NbO7 fluorite microcrystals, and Nb-rich cubic pyrochlore microcrystals. The cubic pyrochlore structure, which was the main phase in this film, has not previously been reported in BNO films. The relative dielectric constant of the BNO film was approximately 140, which is much higher than that of a corresponding film prepared using a conventional vacuum sputtering process. Notably, the cubic pyrochlore microcrystals disappeared with increasing annealing temperature and were replaced with triclinic ?-BiNbO4 crystals at 590 °C. The relative dielectric constant also decreased with increasing annealing temperature. Therefore, the high relative dielectric constant of the BNO film annealed at 550 °C is thought to result from the BNO cubic pyrochlore structure. In addition, the BNO films annealed at 500 °C contained approximately 6.5 atm. % carbon, which was lost at approximately 550 °C. This result suggests that the carbon in the BNO film played an important role in the formation of the cubic pyrochlore structure.

  1. Investigation of solution-processed bismuth-niobium-oxide films

    SciTech Connect

    Inoue, Satoshi, E-mail: s-inoue@jaist.ac.jp [Green Device Research Center, Japan Advanced Institute of Science and Technology (JAIST), 2-13 Asahidai, Nomi, Ishikawa 923-1211 (Japan); School of Material Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Ariga, Tomoki [Green Device Research Center, Japan Advanced Institute of Science and Technology (JAIST), 2-13 Asahidai, Nomi, Ishikawa 923-1211 (Japan); ERATO Shimoda Nano-Liquid Process Project, Japan Science and Technology Agency (JST), 2-13 Asahidai, Nomi, Ishikawa 923-1211 (Japan); Matsumoto, Shin [School of Material Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Onoue, Masatoshi; Miyasako, Takaaki [ERATO Shimoda Nano-Liquid Process Project, Japan Science and Technology Agency (JST), 2-13 Asahidai, Nomi, Ishikawa 923-1211 (Japan); Tokumitsu, Eisuke; Shimoda, Tatsuya [Green Device Research Center, Japan Advanced Institute of Science and Technology (JAIST), 2-13 Asahidai, Nomi, Ishikawa 923-1211 (Japan); School of Material Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); ERATO Shimoda Nano-Liquid Process Project, Japan Science and Technology Agency (JST), 2-13 Asahidai, Nomi, Ishikawa 923-1211 (Japan); Chinone, Norimichi; Cho, Yasuo [Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2014-10-21

    The characteristics of bismuth-niobium-oxide (BNO) films prepared using a solution process were investigated. The BNO film annealed at 550°C involving three phases: an amorphous phase, Bi?NbO? fluorite microcrystals, and Nb-rich cubic pyrochlore microcrystals. The cubic pyrochlore structure, which was the main phase in this film, has not previously been reported in BNO films. The relative dielectric constant of the BNO film was approximately 140, which is much higher than that of a corresponding film prepared using a conventional vacuum sputtering process. Notably, the cubic pyrochlore microcrystals disappeared with increasing annealing temperature and were replaced with triclinic ?-BiNbO? crystals at 590°C. The relative dielectric constant also decreased with increasing annealing temperature. Therefore, the high relative dielectric constant of the BNO film annealed at 550°C is thought to result from the BNO cubic pyrochlore structure. In addition, the BNO films annealed at 500°C contained approximately 6.5 atm.% carbon, which was lost at approximately 550°C. This result suggests that the carbon in the BNO film played an important role in the formation of the cubic pyrochlore structure.

  2. Zinc oxide nanoparticles on silicon

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, K.; Boukos, N.; Travlos, A.

    2006-01-01

    Self-assembled ZnO nanoparticles are grown by electron beam evaporation of Zn on silicon oxide and silicon substrates and subsequent annealing in oxygen. Characterization by TEM and EELS shows that the nanoparticles can be zinc oxide single crystals grown with their c-axis perpendicular to the substrate; their distribution, size and crystallinity depend on the deposition parameters of zinc and the growth substrate. We discuss the effect of these parameters on the morphology of the resulting material.

  3. Room temperature electrodeposition and characterization of bismuth ferric oxide (BFO) thin films from aqueous nitrate bath

    Microsoft Academic Search

    T. P. Gujar; V. R. Shinde; S. S. Kulkarni; H. M. Pathan; C. D. Lokhande

    2006-01-01

    Bismuth ferric oxide (BFO) thin films were prepared on fluorine doped tin oxide (FTO) coated glass substrates using electrodeposition method from aqueous nitrate bath at room temperature. The various preparative parameters, such as bath composition, current density, deposition time, etc were optimized to get good quality BFO thin films. The structural, surface morphological, optical and dielectrical properties of the films

  4. Main group chemistry: Small silicon oxides isolated

    NASA Astrophysics Data System (ADS)

    Apeloig, Yitzhak

    2015-06-01

    Bulk SiO2 is widespread in nature, and silicon oxide clusters are important to a variety of applications, yet molecular silicon oxides have remained elusive. Two molecular compounds featuring silicon oxide moieties, Si2O3 and Si2O4, have now been isolated by oxidation of a carbene-stabilized disilicon precursor.

  5. Catalytic oxidation of propylene--7. Use of temperature programmed reoxidation to characterize. gamma. -bismuth molybdate

    SciTech Connect

    Uda, T.; Lin, T.T.; Keulks, G.W.

    1980-03-01

    Temperature-programed reoxidation of propylene-reduced ..gamma..-Bi/sub 2/MoO/sub 6/ revealed a low-temperature peak (LTP) at 158/sup 0/C and a high-temperature peak (HTP) at 340/sup 0/C. Auger spectroscopy and X-ray diffraction of reduced and partially or completely reoxidized bismuth molybdate showed that at the LTP, molybdenum(IV) is oxidized to molybdenum(VI) and bismuth, from the metallic state to an oxidation state between zero and three, and that the HTP is associated with the complete oxidation of bismuth to bismuth(III). Activity tests for propylene oxidation showed lower acrolein formation on the catalyst, on which only the LTP was reoxidized than on catalysts on which both peaks were reoxidized. The reoxidation kinetics of the catalyst under conditions corresponding to the LTP showed an activation energy of 22.9 kcal/mole below 170/sup 0/C and near zero above 170/sup 0/C; the break in the Arrhenius plot of reoxidation of the catalyst under conditions corresponding to the HTP was at 400/sup 0/C, with activation energies of 46 kcal/mole at lower and near zero at higher temperatures. Propylene oxidation was apparently rate-limited by the HTP reoxidation process below 400/sup 0/C and by allylic hydrogen abstraction above 400/sup 0/C.

  6. Incorporation of thiosemicarbazide in Amberlite IRC50 for separation of astatine from ?-irradiated bismuth oxide

    Microsoft Academic Search

    Kamalika Roy; S. Basu; A. Ramaswami; Dalia Nayak; Susanta Lahiri

    2004-01-01

    A chelating resin was synthesized by incorporating thiosemicarbazide into Amberlite IRC-50, a weakly acidic polymer. Astatine radionuclides produced by ?-irradiating bismuth oxide were separated using the newly synthesized chelating resin. The resin showed high selectivity for astatine. The adsorbed astatine was recovered using 0.1M EDTA at pH?10.

  7. Composite cathode based on yttria stabilized bismuth oxide for low-temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Xia, Changrong; Zhang, Yuelan; Liu, Meilin

    2003-02-01

    Composites consisting of silver and yttria stabilized bismuth oxide (YSB) have been investigated as cathodes for low-temperature honeycomb solid oxide fuel cells with stabilized zirconia as electrolytes. At 600 °C, the interfacial polarization resistances of a porous YSB-Ag cathode is about 0.3 ? cm2, more than one order of magnitude smaller than those of other reported cathodes on stabilized zirconia. For example, the interfacial resistances of a traditional YSZ-lanthanum maganites composite cathode is about 11.4 ? cm2 at 600 °C. Impedance analysis indicated that the performance of an YSB-Ag composite cathode fired at 850 °C for 2 h is severely limited by gas transport due to insufficient porosity. The high performance of the YSB-Ag cathodes is very encouraging for developing honeycomb fuel cells to be operated at temperatures below 600 °C.

  8. Bismuth-promoted palladium catalysts for the selective oxidation of glyoxal into glyoxalic acid

    Microsoft Academic Search

    F Alardin; P Ruiz; B Delmon; M Devillers

    2001-01-01

    The incorporation of bismuth in carbon-supported Pd-based catalysts is shown to increase significantly the catalytic activity in the selective oxidation of glyoxal into glyoxalic acid. Main side products are glycolic acid resulting from Cannizzaro dismutation and oxalic acid, generated by further oxidation of glyoxalic acid. Catalysts characterized by different Bi\\/Pd ratios (with Pd+Bi=10wt.%) were prepared according to various experimental procedures

  9. Promotional Effects of Bismuth on the Formation of Platinum-Bismuth Nanowires Network and the Electrocatalytic Activity toward Ethanol Oxidation

    SciTech Connect

    X Teng; W Du; D Su; Q Wang; A Frenkel

    2011-12-31

    Electrocatalytic activities of Pt and their alloys toward small organic molecules oxidation are highly dependent on their morphology, chemical composition, and electronic structure. Here, we report the synthesis of dendrite-like Pt{sub 95}Bi{sub 5}, Pt{sub 83}Bi{sub 17}, and Pt{sub 76}Bi{sub 24} nanowires network with a high aspect ratio (up to 68). The electronic structure and heterogeneous crystalline structure have been studied using combined techniques, including aberration-corrected scanning transmission electron microscopy (STEM) and X-ray absorption near-edge structure (XANES) spectroscopy. Bismuth-oriented attachment growth mechanism has been proposed for the anisotropic growth of Pt/Bi. The electrochemical activities of Pt/Bi nanowires network toward ethanol oxidations have been tested. In particular, the as-made Pt{sub 95}Bi{sub 5} appears to have superior activity toward ethanol oxidation in comparison with the commercial Pt/C catalyst. The reported promotional effect of Bi on the formation of Pt/Bi and electrochemical activities will be important to design effective catalysts for ethanol fuel cell application.

  10. Recent advances in optical processing techniques using highly nonlinear bismuth oxide fiber

    Microsoft Academic Search

    Mable P. Fok; Chester Shu

    2008-01-01

    We report our recent studies on nonlinear processing of optical signals using a 35-cm highly nonlinear bismuth oxide fiber (Bi-NLF). Our findings are based on self-phase modulation, cross-phase modulation, and four-wave mixing in the Bi-NLF. We demonstrate applications of the nonlinear techniques in optical signal regeneration, tunable optical delay, stabilization of multiwavelength laser source, tunable optical pulse generation, microwave photonic

  11. A SILICON NITRID OxideMEMS L

    E-print Network

    Afshari, Ehsan

    A SILICON NITRID S. OxideMEMS L ABSTRACT We present an integrated chip-scale R driven Opto-OMO) in silicon phase noise. We e opto-mechanical ouplers in silicon MO operating at Hz at 1kHz offset. other

  12. Synthesis and photocatalytic properties of bismuth titanate with different structures via oxidant peroxo method (OPM).

    PubMed

    Nogueira, André E; Longo, Elson; Leite, Edson R; Camargo, Emerson R

    2014-02-01

    Bismuth titanate (Bi4Ti3O12 and Bi12TiO20) powders were synthesized by the Oxidant Peroxide Method (OPM), and the effect of temperatures on physical and chemical properties of particles was investigated. The results showed that the morphology and average particle size of materials can be successfully controlled by adjusting the temperature. The samples after calcination were characterized by X-ray diffractometry, transmission electron microscopy, diffuse reflectance spectroscopy, Raman spectroscopy, and BET isotherms. The photocatalytic activity of materials was also evaluated by studying the degradation of 10ppm aqueous rhodamine B dye under ultraviolet radiation. PMID:24267334

  13. UHV and electrochemical transfer studies on Pt(110)-(1 × 2) : the influence of bismuth on hydrogen and oxygen adsorption, and the electro-oxidation of carbon monoxide

    Microsoft Academic Search

    Brian E. Hayden; Andrew J. Murray; Roger Parsons; David J. Pegg

    1996-01-01

    We have investigated the anodic stripping of bismuth layers adsorbed on Pt(110)-(1 × 2) by metal vapour deposition, and through under-potential deposition (upd) from solution. We have also studied the effect of the bismuth layers on hydrogen and oxygen adsorption in ultra-high vacuum (UHV), upd hydrogen adsorption-desorption, and the electro-oxidation of CO in dilute sulphuric acid electrolyte. A bismuth monolayer

  14. Bismuth doped lanthanum ferrite perovskites as novel cathodes for intermediate-temperature solid oxide fuel cells.

    PubMed

    Li, Mei; Wang, Yao; Wang, Yunlong; Chen, Fanglin; Xia, Changrong

    2014-07-23

    Bismuth is doped to lanthanum strontium ferrite to produce ferrite-based perovskites with a composition of La(0.8-x)Bi(x)Sr0.2FeO(3-?) (0 ? x ? 0.8) as novel cathode material for intermediate-temperature solid oxide fuel cells. The perovskite properties including oxygen nonstoichiometry coefficient (?), average valence of Fe, sinterability, thermal expansion coefficient, electrical conductivity (?), oxygen chemical surface exchange coefficient (K(chem)), and chemical diffusion coefficient (D(chem)) are explored as a function of bismuth content. While ? decreases with x due to the reduced Fe(4+) content, D(chem) and K(chem) increase since the oxygen vacancy concentration is increased by Bi doping. Consequently, the electrochemical performance is substantially improved and the interfacial polarization resistance is reduced from 1.0 to 0.10 ? cm(2) at 700 °C with Bi doping. The perovskite with x = 0.4 is suggested as the most promising composition as solid oxide fuel cell cathode material since it has demonstrated high electrical conductivity and low interfacial polarization resistance. PMID:24971668

  15. Synthesis of yttria-doped bismuth oxide powder by carbonate coprecipitation for IT-SOFC electrolyte.

    PubMed

    Lee, J G; Kim, S H; Yoon, H H

    2011-01-01

    Yttria-doped bismuth oxide (YBO) powders were synthesized by ammonium carbonate coprecipitation for the preparation of electrolytes of an intermediate temperature solid oxide fuel cell (IT-SOFC). The starting salts were yttrium and bismuth nitrate. The crystal structures and the morphological characteristics of the particles were analyzed by XRD and SEM, respectively. The ionic conductivity of the sintered pellet was measured by an electrochemical impedance analyzer. The size of the calcined YBO powders were in the range of 20-100 nm as measured by SEM images. The YBO pellets had a face-centered cubic structure, and their crystallite size was about 54-88 nm. The ionic conductivity of the YBO pellets sintered at 800 degrees C was observed to be 2.7 x 10(-1) Scm-(-1) at 700 degrees C. The ball-milling of the YBO powder before it was pelletized was found to have been unrequired probably because of a good sinterability of the YBO powders that was prepared via the ammonium carbonate coprecipitation method. The results showed that the ammonium carbonate coprecipitation process could be used as the cost-efficient method of producing YBO electrolytes for IT-SOFC. PMID:21446553

  16. Silicon Carbide Nanotube Oxidation at High Temperatures

    NASA Technical Reports Server (NTRS)

    Ahlborg, Nadia; Zhu, Dongming

    2012-01-01

    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

  17. Bismuth oxide coated amorphous manganese dioxide for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Li, Xiaofeng; Zhang, Linsen; Dong, Huichao; Xia, Tongchi; Huang, Zhigang

    2015-05-01

    With MnSO4, NaOH and K2S2O8 as the raw materials, the amorphous and ?-type manganese dioxide (MnO2) is separately prepared by using different chemical precipitation-oxidation methods. The results of charge-discharge and electrochemical impedance spectroscopy (EIS) tests show that (i) the specific capacitance of the amorphous MnO2 reaches to 301.2 F g-1 at a current density of 200 mA g-1 and its capacitance retention rate after 2000 cycles is 97%, which is obviously higher than 250.8 F g-1 and 71% of the ?-type one, respectively; (ii) good electrochemical capacitance properties of the amorphous MnO2 should be contributed to easy insertion/extraction of ions within the material; (iii) when 5 wt% Bi2O3 is coated on the amorphous MnO2, its specific capacitance increases to 352.8 F g-1 and the capacitance retention rate is 90% after 2000 cycles.

  18. Room temperature oxidation of ion bombarded silicon

    NASA Astrophysics Data System (ADS)

    Ponpon, J. P.

    1985-10-01

    The room temperature oxidation of silicon surfaces under air ambient after ion bombardment either during dry etching or during ion implantation has been investigated. Depending on the amount of crystalline damage produced by the ion beams the oxidation kinetics was found to change from the crystalline-like to the amorphous-like behavior.

  19. Investigation of 1.3 ?m emission in Nd 3+-doped bismuth-based oxide glasses

    NASA Astrophysics Data System (ADS)

    Nie, Qiuhua; Li, Xujie; Dai, Shixun; Xu, Tiefeng; Chen, Yanfei; Zhang, Xianghua

    2007-11-01

    Nd 2O 3-doped 43Bi 2O 3- xB 2O 3-(57- x)SiO 2-1.0Nd 2O 3 ( x=57, 47, 39, 28.5, 19.5, 10, 0 mol%) bismuth glasses were prepared by the conventional melt-quenching method, and the Nd 3+: 4F 3/2? 4I 13/2 fluorescence properties had been studied in an oxide system Bi 2O 3-B 2O 3-SiO 2. The Judd-Ofelt analysis for Nd 3+ ions in bismuth boron silicate glasses was also performed on the basis of absorption spectrum, and the transition probabilities, excited-state lifetimes, the fluorescence branching ratios, quantum efficiency and the stimulated emission cross-sections of 4F 3/2? 4I 13/2 transition were calculated and discussed. The stimulated emission cross-sections of 1.3 ?m were quite large due to a large refractive index of the host. Although the effective bandwidths decreased with increasing SiO 2 content, quantum efficiencies and stimulated emission cross-sections enhanced largely with increasing SiO 2 content.

  20. High-performance and wideband amplifier using bismuth-oxide-based EDF with cascade configurations

    NASA Astrophysics Data System (ADS)

    Hayashi, Hideaki; Sugimoto, Naoki; Tanabe, Setsuhisa

    2006-07-01

    We demonstrate high-performance and wideband-bismuth-oxide-based erbium-doped fiber amplifiers (BI-EDFAs) with multi-stage configurations. Cascade configurations that gain flattening filters and isolators inserted between the doped fibers are applied in order to suppress amplified spontaneous emission (ASE). As a result of the optimization of the fiber length, the gain characteristics of the two-stage BI-EDFAs were improved in extended L-band region. The BI-EDFAs for four-channel coarse wavelength division multiplexing (CWDM) systems ranging from 1550-1610 nm are then presented. Three-stage configurations are applied, and a gain of 20 dB and an output power of 20 dB m are simultaneously achieved with practical pumping condition.

  1. Microanalytical study of defect formation in thin bismuth strontium calcium copper oxide films

    SciTech Connect

    Howell, R.H.; Chaiken, A.; Musket, R.G. [and others

    1994-01-01

    Thin bismuth strontium calcium copper oxide (BSCCO) films and (BSCCO) films and BSCCO/insulator/BSCCO trilayers have been prepared on SiTiO{sub 3} and MgO substrates by evaporation from elemental sources in an ozone atmosphere. Accurate control of the stoichiometry is achieved through monitoring of the atomic fluxes by use of in situ atomic absorption spectroscopy as well as by reflection high-energy electron diffraction (RHEED). Nevertheless, nanometer-scale second-phase precipitates are sometimes observed. These defects and the flat regions around them have been probed by a variety of microanalytical techniques, including Rutherford backscattering spectroscopy (RBS), particle-induced x-ray emission (PIXE), atomic force microscopy (AFM), microscopic secondary ion mass spectroscopy and transmission electron microscopy (TEM).

  2. Broadly tunable multiwavelength fiber laser with bismuth-oxide EDF using large effective area fiber

    NASA Astrophysics Data System (ADS)

    Ramzia Salem, A. M.; Al-Mansoori, M. H.; Hizam, H.; Mohd Noor, S. B.; Mahdi, M. A.

    2011-02-01

    A multiwavelength laser comb using 2.49 m Bismuth-oxide erbium-doped fiber (Bi-EDF) with different lengths of large effective area fiber (LEAF) in a ring cavity configuration is realized. The Bi-EDF is used as the linear gain medium and LEAF is used as the non-linear gain medium for stimulated Brillouin scattering. Out of the four different lengths, the longest length of 25 km LEAF exhibits the widest tuning range of 44 nm (1576 to 1620 nm) in the L-band at 264 mW pump power and 5 mW Brillouin pump power. In addition, a total of 15 output channels are achieved with total average output power of -8 dBm from this laser structure. All Brillouin Stokes signals exhibit high peak power of above -20 dBm per signal and their optical signal-to-noise ratio of greater than 15 dB.

  3. Cathodic electrophoretic deposition of bismuth oxide (Bi2O3) coatings and their photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Guo, Xiaogang; Li, Xueming; Lai, Chuan; Li, Wulin; Zhang, Daixiong; Xiong, Zhongshu

    2015-03-01

    In this study, cathodic electrophoretic deposition (EPD), a low cost, one-step and flexible method, has been successfully developed to prepare bismuth oxide (Bi2O3) coatings. Stable suspensions consisted of isopropyl alcohol and trace additive-polyethyleneimine. Deposition was achieved on the cathode at applied field strengths of 5-25 V mm-1 using a total solids loading of 0.5-2 g L-1 at ambient temperature and pressure. The deposition mechanism of Bi2O3 coatings was firstly given, and deposition kinetics were investigated in detail. The deposits were characterized qualitatively by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) observation, atomic force microscope (AFM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis, respectively. Moreover, the photocatalytic activities of obtained coatings were evaluated through degradation of Rhodamine B under ultraviolet and visible light irradiation.

  4. Self-assembled zinc oxide nanodots on silicon oxide

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, K.; Boukos, N.; Travlos, A.

    2005-01-01

    Self assembled ZnO nanodots are grown by electron beam evaporation of Zn on thermally oxidized silicon substrates and subsequent annealing in oxygen. Characterization by TEM and EELS shows that the quantum dots are indeed zinc oxide single crystals grown with their c-axis perpendicular to the substrate; their distribution and size depends on the deposition parameters of zinc onto the substrates.

  5. Oxidized porous silicon moisture sensors for evaluation of microelectronic packaging

    Microsoft Academic Search

    M. J. Kelly; T. R. Guilinger; D. W. Peterson; M. R. Tuck; J. N. Sweet

    1991-01-01

    Accurate moisture measurements in microelectronic assemblies are crucial in assessing reliability of integrated circuits (ICs). We describe the fabrication and use of a silicon-based device for evaluation of moisture barrier coatings. The capacitive moisture sensors use oxidized porous silicon (OPS) as the sensing element. Porous silicon (PS) is formed by anodization of silicon in hydrofluoric acid (HF). Oxidation of PS

  6. Stabilization of a subvalent oxidation state of bismuth in N,N-dimethylthioformamide solution: an EXAFS, UV-Vis, IR, and cyclic voltammetry study.

    PubMed

    Lyczko, Krzysztof; Bilewicz, Aleksander; Persson, Ingmar

    2004-11-01

    At the dissolution of anhydrous bismuth(III) trifluoromethanesulfonate in N,N-dimethylthioformamide (DMTF) a deep red-orange complex, lambda(max) = 457 nm, is formed. Bismuth(III) is reduced by the solvent to a low-valent oxidation state stabilized by the sulfur-coordinating solvent DMTF. The obtained complex is weakly solvated seen by a low EXAFS amplitude and a slightly higher absorption energy of the L(III) edge than of the DMTF-solvated bismuth(III) ion. The EXAFS data reveal a dimeric bismuth complex solvated by a single DMTF molecule, which sulfur atom bridges the bismuth atoms. The Bi-S bond distance is 2.543(2) A, and the Bi...Bi distance is 3.929(7) A giving a Bi-S-Bi angle of 101.2(4) degrees. The very low number of coordinated solvent molecule shows that the lone electron pairs of the reduced bismuth ions are stereochemically active. Cyclic voltammetry investigations provide evidence that at least one bismuth atom in the dimer exists in an oxidation state lower than +III, seen by two peaks at approximately -0.36 and -0.57 V in the reduction half-cycle. The absence of EPR signals excludes the presence of bismuth(II) radicals. PMID:15500347

  7. Synthesis and structural characterization of new bismuth (III) nano coordination polymer: A precursor to produce pure phase nano-sized bismuth (III) oxide

    NASA Astrophysics Data System (ADS)

    Hanifehpour, Younes; Mirtamizdoust, Babak; Hatami, Masoud; Khomami, Bamin; Joo, Sang Woo

    2015-07-01

    A novel bismuth (III) nano coordination polymer, {[Bi (pcih)(NO3)2]?MeOH}n (1), ("pcih" is the abbreviations of 2-pyridinecarbaldehyde isonicotinoylhydrazoneate) were synthesized by a sonochemical method. The new nano-structure was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction, elemental analyses and IR spectroscopy. Single crystalline material was obtained using a heat gradient applied to a solution of the reagents. Compound 1 was structurally characterized by single crystal X-ray diffraction. The determination of the structure by single crystal X-ray crystallography shows that the complex forms a zig-zag one dimensional polymer in the solid state and the coordination number of BiIII ions is seven, (BiN3O4), with three N-donor and one O-donor atoms from two "pcih" and three O-donors from nitrate anions. It has a hemidirected coordination sphere. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The chains interact with each other through ?-? stacking interactions creating a 3D framework. After thermolysis of 1 at 230 °C with oleic acid, pure phase nano-sized bismuth (III) oxide was produced. The morphology and size of the prepared Bi2O3 samples were further observed using SEM.

  8. Charge decay characteristics of silicon-oxide-nitride-oxide-silicon structure at elevated temperatures and extraction of the nitride

    E-print Network

    Lee, Jong Duk

    -oxide-nitride-oxide-silicon type nonvolatile memory at elevated temperatures. Based on the amphoteric trap model and the thermal known attributes of traps in silicon nitride.8 In the amphoteric model, the traps of both charge states

  9. Hybrid carbon nanotube-silicon complementary metal oxide semiconductor circuits

    E-print Network

    Hone, James

    Hybrid carbon nanotube-silicon complementary metal oxide semiconductor circuits I. Merica and V field-effect transistors CNFET with conventional, silicon-based complementary metal oxide semiconductor. © 2007 American Vacuum Society. DOI: 10.1116/1.2800322 I. INTRODUCTION Silicon complementary metal-oxide

  10. Development of tellurium oxide and lead-bismuth oxide glasses for mid-wave infra-red transmission optics

    NASA Astrophysics Data System (ADS)

    Zhou, Beiming; Rapp, Charles F.; Driver, John K.; Myers, Michael J.; Myers, John D.; Goldstein, Jonathan; Utano, Rich; Gupta, Shantanu

    2013-03-01

    Heavy metal oxide glasses exhibiting high transmission in the Mid-Wave Infra-Red (MWIR) spectrum are often difficult to manufacture in large sizes with optimized physical and optical properties. In this work, we researched and developed improved tellurium-zinc-barium and lead-bismuth-gallium heavy metal oxide glasses for use in the manufacture of fiber optics, optical components and laser gain materials. Two glass families were investigated, one based upon tellurium and another based on lead-bismuth. Glass compositions were optimized for stability and high transmission in the MWIR. Targeted glass specifications included low hydroxyl concentration, extended MWIR transmission window, and high resistance against devitrification upon heating. Work included the processing of high purity raw materials, melting under controlled dry Redox balanced atmosphere, finning, casting and annealing. Batch melts as large as 4 kilograms were sprue cast into aluminum and stainless steel molds or temperature controlled bronze tube with mechanical bait. Small (100g) test melts were typically processed in-situ in a 5%Au°/95%Pt° crucible. Our group manufactured and evaluated over 100 different experimental heavy metal glass compositions during a two year period. A wide range of glass melting, fining, casting techniques and experimental protocols were employed. MWIR glass applications include remote sensing, directional infrared counter measures, detection of explosives and chemical warfare agents, laser detection tracking and ranging, range gated imaging and spectroscopy. Enhanced long range mid-infrared sensor performance is optimized when operating in the atmospheric windows from ~ 2.0 to 2.4?m, ~ 3.5 to 4.3?m and ~ 4.5 to 5.0?m.

  11. Output performance investigation of self-phase-modulation-based 2R regenerator using bismuth oxide nonlinear fiber

    Microsoft Academic Search

    Ju Han Lee; Tatsuo Nagashima; Tomoharu Hasegawa; Seiki Ohara; Naoki Sugimoto; Young-Geun Han; Sang Bae Lee; Kazuro Kikuchi

    2006-01-01

    We investigate the feasibility of the use of 1-m length of our fabricated bismuth oxide-based nonlinear fiber (Bi-NLF) for the implementation of a Mamyshev-type 2R regenerator that is based on self-phase-modulation-induced spectral broadening followed by spectral filtering, and evaluate the regeneration performance in both experimental and theoretical ways from a perspective of system application. Owing to the excellent dispersion and

  12. Tailoring Silicon Oxycarbide Glasses for Oxidative Stability

    NASA Technical Reports Server (NTRS)

    Hurwitz, F. I.; Meador, M. A. B.

    1997-01-01

    Blackglas(Trademark) polysiloxane systems produce silicon oxycarbide glasses by pyrolysis in inert atmosphere. The silicon oxycarbides evidence oxidative degradation that limits their lifetime as composite matrices. The present study characterizes bonding rearrangements in the oxycarbide network accompanying increases in pyrolysis temperature. It also addresses the changes in susceptibility to oxidation due to variations in the distribution of Si bonded species obtained under different processing conditions. The study is carried out using Si-29 nuclear magnetic resonance (NMR) spectroscopy and a design of experiments approach to model the oxidation behavior. The NMR results are compared with those obtained by thermogravimetric analysis (TGA). Samples pyrolyzed under inert conditions are compared to those pyrolyzed in reactive ammonia environments.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  15. Boron-Doped Strontium-Stabilized Bismuth Cobalt Oxide Thermoelectric Nanocrystalline Ceramic Powders Synthesized via Electrospinning

    NASA Astrophysics Data System (ADS)

    Koçyi?it, Serhat; Aytimur, Arda; Ç?nar, Emre; Uslu, ?brahim; Akdemir, Ahmet

    2014-01-01

    Boron-doped strontium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by using a polymeric precursor technique. The powders were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), and physical properties measurement system (PPMS) techniques. The XRD results showed that these patterns have a two-phase mixture. The phases are face-centered cubic (fcc) and body-centered cubic (bcc). Values of the crystallite size, dislocation density, and microstrain were calculated by using the Scherrer equation. The lattice parameters were calculated for fcc and bcc phases. The SEM results showed that needle-like grains are formed in boron-undoped composite materials, but the needle-like grains changed to the plate-like grains with the addition of boron. The distribution of the nanofiber diameters was calculated and the average diameter of the boron-doped sample is smaller than the boron-undoped one. PPMS values showed that the electrical resistivity values decreased, but the thermal conductivity values, the Seebeck coefficients, and figure of merit ( ZT) increased with increasing temperature for the two samples.

  16. Metal-oxide-silicon diodes on deuterium-implanted silicon substrate and R. K. Jarwal

    E-print Network

    Misra, Durgamadhab "Durga"

    implantation was used to incorporate deuterium at the Si­SiO2 interface. Polycrystalline silicon gate metal polycrystalline silicon8 and SixNy , used as a sidewall spacer, could limit the transportation of deuteriumPROOF COPY 047021APL Metal-oxide-silicon diodes on deuterium-implanted silicon substrate D. Misraa

  17. A kinetic model for the oxidation of silicon germanium alloys

    NASA Astrophysics Data System (ADS)

    Rabie, Mohamed A.; Haddara, Yaser M.; Carette, Jacques

    2005-10-01

    We propose a complete model for the oxidation of silicon germanium. Our model includes the participation of both silicon and germanium atoms in the oxidation process and the replacement by silicon of germanium in mixed oxides. Our model is capable of predicting, as a function of time, the oxide thickness, the profile of the silicon in the underlying alloy, and the profile of germanium in the oxide. The parameters of the model vary with temperature, alloy composition, and oxidizing ambient. The model shows excellent agreement with published results, with model parameters following trends consistent with the physical phenomena hypothesized. The presence of germanium catalyzes both the silicon and the germanium oxidation rates, and all reaction rates increase with increasing temperature. The resulting effective oxidation rate is enhanced, with respect to the oxidation of pure silicon, at all germanium concentrations. Mixed oxides form only in the case of high germanium concentrations, but at high temperatures the rapid growth of a thick oxide results in a slowing of oxidant diffusion, and the oxide composition switches back to a pure silicon oxide.

  18. Lateral epitaxial growth of germanium on silicon oxide

    SciTech Connect

    Cammilleri, V. D.; Yam, V.; Fossard, F.; Renard, C.; Bouchier, D. [Institut d'Electronique Fondamentale, CNRS UMR 8622, Universite Paris-Sud, Bat 220, 91405 Orsay (France); Fazzini, P. F.; Houdellier, F.; Hyetch, M. [CEMES-CNRS, University of Toulouse, 29, Rue Jeanne Marvig, 31055, Toulouse Cedex 4 (France); Ortolani, L. [CEMES-CNRS, University of Toulouse, 29, Rue Jeanne Marvig, 31055, Toulouse Cedex 4 (France); University of Bologna, Department of Physics, v.le B. Pichat, 6/2, 40127 Bologna (Italy) and CNR-IMM Bologna, v. Gobetti, 101, 40129 Bologna (Italy)

    2008-07-28

    We have developed a method using local oxidation on silicon to create nanoscale silicon seeds for the lateral epitaxial overgrowth of germanium on silicon oxide. The germanium growth starts selectively from silicon seed lines, proceeds by wetting the SiO{sub 2} layer and coalesces without formation of grain boundary. Analysis by high resolution transmission electron microscopy have shown that Ge layers grown above silicon oxide are perfectly monocrystalline and are free of defect. The only detected defects are situated at the Ge/Si interface. Geometrical phase analyses of the microscopy images have shown that the Ge layer is fully relaxed and homogeneous.

  19. CO2 Laser Annealing on Fluorinated Silicon Oxide Films

    Microsoft Academic Search

    Na-Fu Wang; Mau-Phon Houng; Yeong-Her Wang

    1999-01-01

    CO2 laser annealing of fluorinated silicon oxide films grown by liquid-phase deposition (LPD) is proposed to improve the properties of the as-deposited films. It is found that the fluorinated silicon oxide films after laser annealing become much denser and that the effective surface charge density (QSS\\/q) is reduced significantly. However, the properties of the fluorinated silicon oxide films after laser

  20. Thermoelectrics from silicon nanoparticles: the influence of native oxide

    NASA Astrophysics Data System (ADS)

    Petermann, Nils; Stötzel, Julia; Stein, Niklas; Kessler, Victor; Wiggers, Hartmut; Theissmann, Ralf; Schierning, Gabi; Schmechel, Roland

    2015-06-01

    Thermoelectric materials were synthesized by current-assisted sintering of doped silicon nanoparticles produced in a microwave-plasma reactor. Due to their affinity to oxygen, the nanoparticles start to oxidize when handled in air and even a thin surface layer of native silicon oxide leads to a significant increase in the oxide volume ratio. This results in a considerable incorporation of oxygen into the sintered pellets, thus affecting the thermoelectric performance. To investigate the necessity of inert handling of the raw materials, the thermoelectric transport properties of sintered nanocrystalline silicon samples were characterized with respect to their oxygen content. An innovative method allowing a quantitative silicon oxide analysis by means of electron microscopy was applied: the contrast between areas of high and low electrical conductivity was attributed to the silicon matrix and silicon oxide precipitates, respectively. Thermoelectric characterization revealed that both, electron mobility and thermal conductivity decrease with increasing silicon oxide content. A maximum figure of merit with zT = 0.45 at 950 °C was achieved for samples with a silicon oxide mass fraction of 9.5 and 21.4% while the sample with more than 25% of oxygen clearly indicates a negative impact of the oxygen on the electron mobility. Contribution to the Topical Issue "Silicon and Silicon-related Materials for Thermoelectricity", edited by Dario Narducci.

  1. The Active Oxidation of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Myers, Dwight L.

    2009-01-01

    The high temperature oxidation of silicon carbide occurs in two very different modes. Passive oxidation forms a protective oxide film which limits further attack of the SiC: SiC(s) + 3/2 O2(g) = SiO2(s) + CO(g) Active oxidation forms a volatile oxide and may lead to extensive attack of the SiC: SiC(s) + O2(g) = SiO(g) + CO(g) Generally passive oxidation occurs at higher oxidant pressures and active oxidation occurs at lower oxidant pressures and elevated temperatures. Active oxidation is a concern for reentry, where the flight trajectory involves the latter conditions. Thus the transition points and rates of active oxidation are a major concern. Passive/active transitions have been studied by a number of investigators. An examination of the literature indicates many questions remain regarding the effect of impurity, the hysteresis of the transition (i.e. the difference between active-to-passive and passive-toactive), and the effect of total pressure. In this study we systematically investigate each of these effects. Experiments were done in both an alumina furnace tube and a quartz furnace tube. It is known that alumina tubes release impurities such as sodium and increase the kinetics in the passive region [1]. We have observed that the active-to-passive transition occurs at a lower oxygen pressure when the experiment is conducted in alumina tubes and the resultant passive silica scale contains sodium. Thus the tests in this study are conducted in quartz tubes. The hysteresis of the transition has been discussed in the detail in the original theoretical treatise of this problem for pure silicon by Wagner [2], yet there is little mention of it in subsequent literature. Essentially Wagner points out that the active-to-passive transition is governed by the criterion for a stable Si/SiO2 equilibria and the passive-to-active transition is governed by the decomposition of the SiO2 film. A series of experiments were conducted for active-to-passive and passive-to-active transitions by increasing and decreasing oxygen pressure, respectively. For pure silicon a dramatic difference was found; whereas for SiC the difference was not as great. This may be due to the oxidation of the carbon in SiC which may break down the scale [3]. The third area is the effect of total pressure. In the literature, low oxygen potentials are achieved via either low total pressure or low oxygen pressure in an O2/Ar mixture. Both types of experiments are done in this study and the differences are discussed with regard to the presence or absence of a boundary layer.

  2. Sputtered iron oxide/silicon heterostructures

    NASA Astrophysics Data System (ADS)

    Kardauskas, M. J.; Fonash, S. J.; Ashok, S.; Krishnaswamy, S. V.; Messier, R. F.

    1981-03-01

    Sputtered Fe3O4 films are shown to form rectifying junctions to p-type silicon but ohmic contacts to n-type Si. It is pointed out that ohmic contacts to the Fe3O4 can be provided by Au, Al, or spray-deposited ITO. The redox couple Fe(CN)6(3-)/Fe(CN)6(4-) also seems to make an effective ohmic contact to this iron oxide. It is found that the photovoltaic and electrical characteristics of the Fe3O4/p-Si heterojunction depend strongly on the Fe3O4 film thickness.

  3. Bismuth oxide-coated (La,Sr)MnO 3 cathodes for intermediate temperature solid oxide fuel cells with yttria-stabilized zirconia electrolytes

    Microsoft Academic Search

    Zhiyi Jiang; Lei Zhang; Lili Cai; Changrong Xia

    2009-01-01

    Taking Y2O3 stabilized Bi2O3 (YSB) as an example, bismuth oxide-added (La,Sr)MnO3 (LSM) is evaluated as a cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) with 8mol% Y2O3 stabilized ZrO2 (YSZ) electrolytes. YSB was added to LSM cathodes using an impregnation method, dramatically improving the electrode performance. The interfacial polarization resistance Rp, at 700°C for the electrode coated with 50wt.%

  4. Ceramic oxide coatings for the corrosion protection of silicon carbide

    Microsoft Academic Search

    M. van Roode; J. R. Price; C. Stala

    1993-01-01

    Silicon carbide is currently used as a structural material for heat exchanger tubes and related applications because of its excellent thermal properties and oxidation resistance. Silicon carbide suffers corrosion degradation, however, in the aggressive furnace environments of industrial processes for aluminum remelting, advanced glass melting, and waste incineration. Adherent ceramic oxide coatings developed at Solar Turbines Incorporated, with the support

  5. CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS

    E-print Network

    Hart, Gus

    CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS by David T. Oliphant. Woolley Dean, College of Physical and Mathematical Sciences #12;ABSTRACT CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS David T. Oliphant Department of Physics and Astronomy

  6. Fabrication and testing of oxidized porous silicon field emitter strips 

    E-print Network

    Madduri, Vasanta Bhanu

    1992-01-01

    Suucture (Spindt, et al) Fabrication Procedure to Produce Mo Cones Page Vanadium Carbide Fibers Method to Produce Mo Gate Cross-section of Si Pyramids Silicon Field Emitter Array Oxidized Porous Silicon Field Emitting Device Structure of the Porous...FABRICATION AND TESTING OF OXIDIZED POROUS SILICON FIELD EM11TER STRIPS A Thesis by VASANTA BHANU MADDURI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER...

  7. Laser-induced oxidation kinetics of bismuth surface microdroplets on GaAsBi studied in situ by Raman microprobe analysis.

    PubMed

    Steele, J A; Lewis, R A

    2014-12-29

    We report the cw-laser-induced oxidation of molecular-beam-epitaxy grown GaAsBi bismuth surface microdroplets investigated in situ by micro-Raman spectroscopy under ambient conditions as a function of irradiation power and time. Our results reveal the surface droplets are high-purity crystalline bismuth and the resultant Bi2O3 transformation to be ?-phase and stable at room temperature. A detailed Raman study of Bi microdroplet oxidation kinetics yields insights into the laser-induced oxidation process and offers useful real-time diagnostics. The temporal evolution of new ?-Bi2O3 Raman modes is shown to be well described by Johnson-Mehl-Avrami-Kolmogorov kinetic transformation theory and while this study limits itself to the laser-induced oxidation of GaAsBi bismuth surface droplets, the results will find application within the wider context of bismuth laser-induced oxidation and direct Raman laser processing. PMID:25607191

  8. Silicon nanocrystal memories by LPCVD of amorphous silicon, followed by solid phase crystallization and thermal oxidation

    NASA Astrophysics Data System (ADS)

    Tsoi, E.; Normand, P.; Nassiopoulou, A. G.; Ioannou-Sougleridis, V.; Salonidou, A.; Giannakopoulos, K.

    2005-01-01

    Silicon nanocrystals memory cells of an n-MOSFET type were fabricated and tested, based on a silicon nanocrystal gate MOS structure fabricated by low-pressure chemical vapor deposition (LPCVD) of amorphous silicon (?-Si) on a tunneling silicon dioxide layer, followed by solid phase crystallization and high temperature thermal oxidation. A layer of silicon nanocrystals embedded in SiO2 at a tunneling distance (3.5 nm) from the silicon substrate was thus formed. The obtained memory cells showed a full-write, full-erase memory window of the order of 0.5 V under charging with pulses of 7 V and -8 V respectively at 100 ms.

  9. Polarization-Insensitive Wavelength Conversion of DPSK Signal Using Four-Wave Mixing in 32-cm Bismuth-Oxide Highly Nonlinear Fiber

    Microsoft Academic Search

    Mable P. Fok; Chester Shu

    2007-01-01

    We demonstrate polarization-insensitive wavelength conversion of 10-Gb\\/s DPSK signal using a polarization-diversity scheme for four-wave mixing in 32-cm bismuth-oxide highly nonlinear fiber. The polarization dependence is <1 dB and the power penally is 3 dB.

  10. Study of ternary-component bismuth molybdate catalysts by /sup 18/O/sub 2/ tracer in the oxidation of propylene to acrolein

    SciTech Connect

    Ueda, W.; Moro-oka, Y.; Ikawa, T.

    1981-08-01

    Participation of lattice oxide ions of ternary-component bismuth molybdate catalysts M-Bi-Mo-O (M = Ni, Co, Mg, Mn, Ca, Sr, Ba, and Pb) was investigated using the /sup 18/O/sub 2/ tracer in the selective oxidation of propylene to acrolein. The participation of the lattice oxide ions in the oxidation is prominent on every catalyst but the extent of the participation varies significantly depending on the structure of the catalyst. Only lattice oxide ions in the bismuth molybdate phase are incorporated into the oxidized products on the catalysts (M = Ni, Co, Mg, and Mn) where M have smaller ionic radius than Bi/sup 3 +/; catalyst particles are composed of a shell of bismuth molybdates and a core of MMoO/sub 4/. On the other hand, whole oxide ions in the active particles are involved in the oxidation on catalysts having a scheelite-type structure (M = Ca, Sr, Ba, and Pb) where M has a comparable ionic radius to Bi/sup 3 +/.

  11. Immunotoxicity of silicone: implications of oxidant balance towards adjuvant activity.

    PubMed

    Yoshida, S H; Teuber, S S; German, J B; Gershwin, M E

    1994-11-01

    A variety of mechanisms can be proposed to explain the potential effects of silicone and silicone by-products on the immune response. In this paper, we discuss information on the chemistry of silicon and silicone gels/elastomers, and the manufacture of silicone breast implants as they pertain to the bioreactivity of silicone. Moreover, with reference to silicone-mediated human adjuvant disease, an overview of experimental adjuvant-induced arthritis is presented; comparisons with graft-versus-host disease and chemically induced autoimmunity then follow. Particular attention is paid to similarities in the characteristics of silicone and classic lipid adjuvants. For example, macrophage activation is presumed to be a central event in silicone-induced autoimmunity. Since those genes uniquely expressed in macrophages activated by plastic adherence are similar to those induced by lipopolysaccharide, adherence to silicone rubber may initiate an inflammatory response by the same mechanism. Macrophage effects would also include the erosion of implants through the generation of oxidants and localized pH changes. The degradation products of silicone are also implicated in the adjuvant effects of silicone implants. There is evidence to suggest that oxidants produced by inflammatory cells preferentially inactivate CD8+ suppressor T cells. This could then lead to an inflammatory state, perhaps through oxidant-induced transcription factors such as NF-kB, resulting in a long-term pro-oxidant imbalance that manifests itself as a breakdown in immunological self-tolerance. The authors hypothesize that autoreactivity following oxidant stress evolved to enhance inflammatory repair mechanisms after tissue, cell or molecular damage by oxidants. PMID:7959464

  12. Ceramic oxide coatings for the corrosion protection of silicon carbide

    SciTech Connect

    Roode, M. van; Price, J.R. (Solar Turbines Incorporated, San Diego, CA (United States)); Stala, C. (Salomon Brothers, New York, NY (United States))

    1993-01-01

    Silicon carbide is currently used as a structural material for heat exchanger tubes and related applications because of its excellent thermal properties and oxidation resistance. Silicon carbide suffers corrosion degradation, however, in the aggressive furnace environments of industrial processes for aluminum remelting, advanced glass melting, and waste incineration. Adherent ceramic oxide coatings developed at Solar Turbines Incorporated, with the support of the Gas Research Institute, have been shown to afford corrosion protection to silicon carbide in a simulated aluminum remelt furnace environment as well as in laboratory-type corrosion testing. The coatings are also protective to silicon carbide-based ceramic matrix composites.

  13. Nitric oxide-releasing porous silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Kafshgari, Morteza Hasanzadeh; Cavallaro, Alex; Delalat, Bahman; Harding, Frances J.; McInnes, Steven JP; Mäkilä, Ermei; Salonen, Jarno; Vasilev, Krasimir; Voelcker, Nicolas H.

    2014-07-01

    In this study, the ability of porous silicon nanoparticles (PSi NPs) to entrap and deliver nitric oxide (NO) as an effective antibacterial agent is tested against different Gram-positive and Gram-negative bacteria. NO was entrapped inside PSi NPs functionalized by means of the thermal hydrocarbonization (THC) process. Subsequent reduction of nitrite in the presence of d-glucose led to the production of large NO payloads without reducing the biocompatibility of the PSi NPs with mammalian cells. The resulting PSi NPs demonstrated sustained release of NO and showed remarkable antibacterial efficiency and anti-biofilm-forming properties. These results will set the stage to develop antimicrobial nanoparticle formulations for applications in chronic wound treatment.

  14. Evaluation of Radiation Dose Reduction during CT Scans Using Oxide Bismuth and Nano-Barium Sulfate Shields

    E-print Network

    Seoung, Youl-Hun

    2015-01-01

    The purpose of the present study was to evaluate radiation dose reduction and image quality during CT scanning by using a new dose reduction fiber sheet (DRFS) with commercially available bismuth shields. These DRFS were composed of nano-barium sulfate (BaSO4), filling the gaps left by the large oxide bismuth (Bi2O3) particle sizes. The radiation dose was measured five times at directionss of 12 o'clock from the center of the polymethyl methacrylate (PMMA) head phantom to calculate an average value using a CT ionization chamber. The image quality measured CT transverse images of the PMMA head phantom depending on X-ray tube voltages and the type of shielding. Two regions of interest in CT transverse images were chosen from the right and left areas under the surface of the PMMA head phantom and from ion chamber holes located at directions of 12 o'clock from the center of the PMMA head phantom. The results of this study showed that the new DRFS shields could reduce dosages to 15.61%, 23.05%, and 22.71% more in ...

  15. New synthesis of bismuth oxide nanoparticles Bi2O3 assisted by tannic acid

    NASA Astrophysics Data System (ADS)

    Ascencio Aguirre, Francisco Miguel; Herrera Becerra, Raúl

    2015-06-01

    A new and simple method of biosynthesis assisted by tannic acid (C76H52O46) is used to obtain bismuth trioxide nanoparticles Bi2O3 in which the ?-Bi2O3 phase is identified. Synthesis takes place at room temperature and atmospheric pressure from the reduction of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) in solution, using tannic acid as a reducing agent and stabilizer. Nanoparticles with an average size of 10.99 ± 0.27 nm are obtained, and the structural properties of the nanoparticles are observed using transmission electron microscopy techniques, as well as UV-Visible-NIR spectroscopy, with which a semiconductor behavior with band gap within a range of (2.57-3.02) eV is observed. Using Raman spectroscopy, it is possible to observe and identify different normal modes of vibration, characteristic of the ?-Bi2O3 phase.

  16. Study of multiphasic molybdate-based catalysts. II. Synergy effect between bismuth molybdates and mixed iron and cobalt molybdates in mild oxidation of propene

    SciTech Connect

    Millet, J.M.M.; Ponceblanc, H.; Coudurier, G.; Vedrine, J.C. (Institut de Recherches sur la Catalyse, Villeurbanne (France)); Herrmann, J.M. (Laboratoire de Photocatalyse, Ecully (France))

    1993-08-01

    Results are reported concerning the synergy effect observed in the oxidation of propene to acrolein over bismuth and mixed iron and cobalt molybdates. The pure bismuth, iron, and cobalt molybdates and mixed cobalt and iron molybdates (solid solutions) have been prepared and individually tested as catalysts. Mechanical mixtures of these phases have been prepared and tested as catalysts. All the catalysts have been characterized before and after the catalytic reaction by several techniques such as ESR, XPS, EDX-STEM, TEM, XRD, and Moessbauer and UV spectroscopies. The synergy effect observed is tentatively explained as due to the deposition on the large bismuth molybdate particles of smaller mixed iron and cobalt molybdate particles with spreading of the bismuth molybdate over the latter particles. It is proposed that the Fe[sub x]Co[sub 1-x]MoO[sub 4] phase plays the role of the fast electron conducting material which enhances the electron mobility and the efficiency of the redox mechanism, the active and selective phase being the overlying bismuth molybdate compounds. 27 refs., 5 figs., 7 tabs.

  17. Structural, electrical, and thermoelectric properties of bismuth telluride: Silicon/carbon nanocomposites thin films

    SciTech Connect

    Agarwal, Khushboo; Mehta, B. R., E-mail: brmehta@physics.iitd.ac.in [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2014-08-28

    In this study, the effect of the presence of secondary phases on the structural, electrical, and thermoelectric properties of nanocomposite Bi{sub 2}Te{sub 3} films prepared by co-sputtering of silicon and carbon with Bi{sub 2}Te{sub 3} has been investigated. Growth temperature and the presence of Si and C phase are observed to have a strong effect on the topography and orientation of crystallites. X-ray diffraction study demonstrates that Bi{sub 2}Te{sub 3} and Bi{sub 2}Te{sub 3}:C samples have preferred (0 0 15) orientation in comparison to Bi{sub 2}Te{sub 3}:Si sample, which have randomly oriented crystallites. Atomic force, conducting atomic force, and scanning thermal microscopy analysis show significant differences in topographical, electrical, and thermal conductivity contrasts in Bi{sub 2}Te{sub 3}:Si and Bi{sub 2}Te{sub 3}:C samples. Due to the randomly oriented crystallites and the presence of Si along the crystallite boundaries, appreciable Seebeck coefficient, higher electrical conductivity, and lower thermal conductivity is achieved resulting in relatively higher value of power factor (3.71 mW K{sup ?2} m{sup ?1}) for Bi{sub 2}Te{sub 3}:Si sample. This study shows that by incorporating a secondary phase along crystallite boundaries, microstructural, electrical, and thermoelectric properties of the composite samples can be modified.

  18. Structural, electrical, and thermoelectric properties of bismuth telluride: Silicon/carbon nanocomposites thin films

    NASA Astrophysics Data System (ADS)

    Agarwal, Khushboo; Mehta, B. R.

    2014-08-01

    In this study, the effect of the presence of secondary phases on the structural, electrical, and thermoelectric properties of nanocomposite Bi2Te3 films prepared by co-sputtering of silicon and carbon with Bi2Te3 has been investigated. Growth temperature and the presence of Si and C phase are observed to have a strong effect on the topography and orientation of crystallites. X-ray diffraction study demonstrates that Bi2Te3 and Bi2Te3:C samples have preferred (0 0 15) orientation in comparison to Bi2Te3:Si sample, which have randomly oriented crystallites. Atomic force, conducting atomic force, and scanning thermal microscopy analysis show significant differences in topographical, electrical, and thermal conductivity contrasts in Bi2Te3:Si and Bi2Te3:C samples. Due to the randomly oriented crystallites and the presence of Si along the crystallite boundaries, appreciable Seebeck coefficient, higher electrical conductivity, and lower thermal conductivity is achieved resulting in relatively higher value of power factor (3.71 mW K-2 m-1) for Bi2Te3:Si sample. This study shows that by incorporating a secondary phase along crystallite boundaries, microstructural, electrical, and thermoelectric properties of the composite samples can be modified.

  19. Analysis of phosphorous autodoping in P-type silicon measured using corona oxide silicon (COS) techniques

    NASA Astrophysics Data System (ADS)

    Letherer, Brian; Horner, Gregory

    1999-08-01

    Semiconductor fabrication facilities rely on the integrity of the silicon to manufacture sub-micron devices. Cross contamination of P-type silicon to N-type carriers or vice versa in the near surface region of the silicon can be detrimental to device performance. Semiconductor processing typically includes numerous diffusion and pre-clean steps, any one of which might auto-dope P-type silicon substrate with phosphorous. Inline monitoring of these near surface doping effects enhances the ability to diagnose autodoping problems. A non-contact Corona Oxide Silicon (COS) measurement technique has the ability to detect cross-contaminated P-type silicon with phosphorous from wet clean benches and diffusion furnaces. Results show COS flatband (Vfb) and oxide total charge (Qtot) measurements are sensitive to various levels of intentional phosphorous contamination implanted into the silicon at pre-oxidation. Phosphorous at the silicon/oxide interface can pile up and create an electrically active thin 'N' skin. Phosphorous from this thin 'N' skin is shown to change the electrical characteristics of near surface region of the silicon. The detection of unwanted phosphorus with the use of COS inline monitoring can greatly reduce the response time when auto-doping problems occur.

  20. One-step synthesis of bismuth molybdate catalysts via flame spray pyrolysis for the selective oxidation of propylene to acrolein.

    PubMed

    Schuh, K; Kleist, W; Høj, M; Trouillet, V; Jensen, A D; Grunwaldt, J-D

    2014-12-18

    Flame spray pyrolysis (FSP) of Bi(III)- and Mo(VI)-2-ethylhexanoate dissolved in xylene resulted in various nanocrystalline bismuth molybdate phases depending on the Bi/Mo ratio. Besides ?-Bi2Mo3O12 and ?-Bi2MoO6, FSP gave direct access to the metastable ?-Bi2Mo2O9 phase with high surface area (19 m(2) g(-1)). This phase is normally only obtained at high calcination temperatures (>560 °C) resulting in lower surface areas. The ?-phase was stable up to 400 °C and showed superior catalytic performance compared to ?- and ?-phases in selective oxidation of propylene to acrolein at temperatures relevant for industrial applications (360 °C). PMID:25350295

  1. Silicon oxide colloidal/polymer nanocomposite films Haifeng Wanga)

    E-print Network

    Cao, Wenwu

    techniques, sol-gel process is one of the technologies for the develop- ment of nanostructure materials, thin to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle layer coating, nano powders, fibers, and thin films because the method can pro- duce high homogeneity

  2. Passivation of silicon power devices by thermal oxidation

    Microsoft Academic Search

    A. Neidig; G. Wahl; K. Weimann; G. Gilbers

    1979-01-01

    A method was developed for the passivation of high voltage silicon power devices replacing the usually applied sensitive silicon polymers on the edge beveling of the pn junctions. The new passivation is produced at temperatures between 600 C and 900 C by thermal oxidation followed by chemical vapor deposition of a barrier layer against alkaline impurities. The barrier layers are

  3. Porous silicon oxide anti-reflection coating for solar cells

    Microsoft Academic Search

    A. Prasad; S. Balakrishnan; S. K. Jain; G. C. Jain

    1982-01-01

    A very useful anti-reflection (AR) coating, having characteristics quite similar to silicon monoxide, has been grown on P(+)N solar cells by a simple technique. ESCA, infrared absorption, and ellipsometry analysis of the films indicated that they consist of silicon oxide with some bound hydrogen. Some added advantages of the new AR coating are described.

  4. Indium oxide/n-silicon heterojunction solar cells

    DOEpatents

    Feng, Tom (Morris Plains, NJ); Ghosh, Amal K. (New Providence, NJ)

    1982-12-28

    A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

  5. Aspects of selective oxidation and ammoxidation mechanisms over bismuth molybdate catalysts--2. Allyl alcohol as a probe for the allylic intermediate

    SciTech Connect

    Burrington, J.D.; Kartisek, C.T.; Grasselli, R.K.

    1980-05-01

    Pulse reactor experiments were conducted on the reactions of unlabeled or deuterium- or oxygen-18-labeled allyl alcohols over molybdenum trioxide and various bismuth molybdates in the absence or presence of oxygen and ammonia. The allyl alcohol apparently adsorbed on oxidation sites to form acrolein via allyl molybdates, and on Broensted acid sites to form diallyl ether via an allyl carbonium ion. The bismuth enhanced ..cap alpha..-hydrogen abstraction, which was the rate-determining step in the oxidation. The product distributions provided evidence that the selective oxidation of propylene to acrolein proceeds via a m-allyl molybdate which collapses to an O o-allyl molybdate prior to the second hydrogen abstraction, and that the analogous N o-complex in ammoxidation undergoes two hydrogen abstractions to form acrylonitrile. Detailed reaction schemes are developed.

  6. Oxidation-Induced Trapping of Drugs in Porous Silicon Microparticles

    PubMed Central

    2015-01-01

    An approach for the preparation of an oxidized porous silicon microparticle drug delivery system that can provide efficient trapping and sustained release of various drugs is reported. The method uses the contraction of porous silicon’s mesopores, which occurs during oxidation of the silicon matrix, to increase the loading and retention of drugs within the particles. First, a porous Si (pSi) film is prepared by electrochemical etching of p-type silicon with a resistivity of >0.65 ? cm in a 1:1 (v/v) HF/ethanol electrolyte solution. Under these conditions, the pore walls are sufficiently thin to allow for complete oxidation of the silicon skeleton under mild conditions. The pSi film is then soaked in an aqueous solution containing the drug (cobinamide or rhodamine B test molecules were used in this study) and sodium nitrite. Oxidation of the porous host by nitrite results in a shrinking of the pore openings, which physically traps the drug in the porous matrix. The film is subsequently fractured by ultrasonication into microparticles. Upon comparison with commonly used oxidizing agents for pSi such as water, peroxide, and dimethyl sulfoxide, nitrite is kinetically and thermodynamically sufficient to oxidize the pore walls of the pSi matrix, precluding reductive (by Si) or oxidative (by nitrite) degradation of the drug payload. The drug loading efficiency is significantly increased (by up to 10-fold), and the release rate is significantly prolonged (by 20-fold) relative to control samples in which the drug is loaded by infiltration of pSi particles postoxidation. We find that it is important that the silicon skeleton be completely oxidized to ensure the drug is not reduced or degraded by contact with elemental silicon during the particle dissolution–drug release phase. PMID:25678746

  7. Zinc oxide varistors and/or resistors

    DOEpatents

    Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

    1993-01-01

    Varistors and/or resistors that includes doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

  8. Zinc oxide varistors and/or resistors

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-07-27

    Varistors and/or resistors are described that include doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

  9. Oxidation of silicon-germanium alloys. II. A mathematical model

    NASA Astrophysics Data System (ADS)

    Hellberg, P.-E.; Zhang, S.-L.; d'Heurle, F. M.; Petersson, C. S.

    1997-12-01

    A mathematical model of oxidation of SixGe1-x alloys is presented. The growth of SiO2 is simulated in conjunction with the determination of silicon distribution in SixGe1-x using numerical methods. The main feature of the model is the assumption of simultaneous oxidation of germanium and silicon when exposing the SixGe1-x to an oxidizing atmosphere. In accordance with thermodynamics, the GeO2 formed is subsequently reduced by the (free) silicon available at the interface between the growing SiO2 and the remaining SixGe1-x through a reduction reaction. Thus, the enhanced oxidation of silicon in the presence of germanium is modeled as a result of the rapid oxidation of germanium followed by the quick reduction of GeO2 by silicon. The growth of a mixed oxide in the form of either (Si,Ge)O2 or SiO2-GeO2 only occurs when the supply of silicon to the SiO2/SixGe1-x interface is insufficient. A comparison is made between simulation and experiment for wet oxidation (in pyrogenic steam) of polycrystalline SixGe1-x films. It is found that the model gives a good account of the oxidation process. Kinetic parameters, i.e., interfacial reaction rate constant for oxidation of germanium and diffusion coefficient of silicon (germanium) in SixGe1-x, are extracted by fitting the simulation to the experiment.

  10. Rapid thermal processing of thin gate dielectrics. Oxidation of silicon

    Microsoft Academic Search

    J. Nulman; J. P. Krusius; A. Gat

    1985-01-01

    A new rapid process for the growth of thin thermal oxide films on crystalline silicon is described. This rapid thermal oxidation (RTO) is performed in a controlled oxygen ambient with the heating provided by tungsten-halogen lamps. The resulting oxides with thicknesses from 40-130 Å have a uniformity of better than 2 percent across the 75-mm wafers. Oxidation times at 1150°C

  11. Efficient and Sustained Photoelectrochemical Water Oxidation by Cobalt Oxide/Silicon Photoanodes with Nanotextured Interfaces

    E-print Network

    Javey, Ali

    Efficient and Sustained Photoelectrochemical Water Oxidation by Cobalt Oxide/Silicon Photoanodes photoanodes that operate in alkaline conditions is vital to achieve an efficient solar-to-fuel system. Silicon aqueous conditions, particularly at high pH. In recent years, strategies for stabilizing photoanodes

  12. Bismuth Spheres Grown in Self-Nested Cavities in a Silicon Hong Liu, and Zhong Lin Wang*,

    E-print Network

    Wang, Zhong L.

    cleaned sequentially using H2SO4/H2O2 [H2SO4 (97%) + H2O2 (30%)] (90 °C, 30 min), de- ionized water and excellent thermoelectric properties.3 In recent years, synthesis and property characterization of bismuth, nanoplates, and nanoballs through different synthesis routes.4 In this paper, we report a distinct and novel

  13. Light emission and detection by metal oxide silicon tunneling diodes

    Microsoft Academic Search

    C. W. Liu; M. H. Lee; C. F. Lin; I. C. Lin; W. T. Liu; H. H. Lin

    1999-01-01

    Both NMOS and PMOS light-emitting diodes and photodetectors are demonstrated. For the ultrathin gate oxide, the tunneling gate of metal oxide silicon (MOS) diodes can be utilized as both emitters for light emitting devices and collectors for light detectors. An electron-hole plasma model is used to fit the emission spectra. A surface band bending is responsible for the bandgap reduction

  14. Protein adsorption in thermally oxidized porous silicon layers

    Microsoft Academic Search

    S. Zangooie; R Bjorklund; H Arwin

    1998-01-01

    Variable angle spectroscopic ellipsometry was employed for multilayer characterization of thermally oxidized porous silicon layers and for quantitative adsorption studies of human serum albumin and fibrinogen in these layers. The oxidized samples were used either as prepared or were hydrated in a deionized water bath prior to their use. Hydration decreased the volume percentage of adsorbed albumin from 24 to

  15. Multiwavelength L-band fiber laser with bismuth-oxide EDF and photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Ramzia Salem, A. M.; Al-Mansoori, M. H.; Hizam, H.; Mohd Noor, S. B.; Abu Bakar, M. H.; Mahdi, M. A.

    2011-05-01

    A multiwavelength laser comb using a bismuth-based erbium-doped fiber and 50 m photonic crystal fiber is demonstrated in a ring cavity configuration. The fiber laser is solely pumped by a single 1455 nm Raman pump laser to exploit its higher power delivery compared to that of a single-mode laser diode pump. At 264 mW Raman pump power and 1 mW Brillouin pump power, 38 output channels in the L-band have been realized with an optical signal-to-noise ratio above 15 dB and a Stokes line spacing of 0.08 nm. The laser exhibits a tuning range of 12 nm and produces stable Stokes lines across the tuning range between Brillouin pump wavelengths of 1603 nm and 1615 nm.

  16. Tunable Optical Delay Using Four-Wave Mixing in a 35-cm Highly Nonlinear Bismuth-Oxide Fiber and Group Velocity Dispersion

    Microsoft Academic Search

    Mable P. Fok; Chester Shu

    2008-01-01

    In this paper, an optically controlled tunable delay scheme has been proposed using four-wave mixing (FWM) wavelength conversion in a 35-cm highly nonlinear bismuth-oxide fiber (Bi-NLF) together with group velocity dispersion (GVD) in a chirped fiber Bragg grating (CFBG). The Bi-NLF offers a very large nonlinearity and gives rise to significant FWM over a short fiber segment. With the use

  17. Bismuth-oxide-based nonlinear fiber with a high SBS threshold and its application to four-wave-mixing wavelength conversion using a pure continuous-wave pump

    Microsoft Academic Search

    Ju Han Lee; Tatsuo Nagashima; Tomoharu Hasegawa; Seiki Ohara; Naoki Sugimoto; Kazuro Kikuchi

    2006-01-01

    The unique and practical benefits of the use of bismuth-oxide-based nonlinear fiber (Bi-NLF) in implementing a four-wave-mixing (FWM)-based wavelength converter for fiber-optic-communication-system applications are experimentally demonstrated. First, the Kerr-nonlinearity and stimulated-Brillouin-scattering (SBS) characteristics of our fabricated Bi-NLF are experimentally investigated. The Bi-NLF is found to have the superior advantage of a significantly high SBS threshold in addition to its ultrahigh

  18. Preparation and characterization of bismuth oxide nanoparticles-multiwalled carbon nanotube composite for the development of horseradish peroxidase based H 2O 2 biosensor

    Microsoft Academic Search

    Arun Prakash Periasamy; Singying Yang; Shen-Ming Chen

    In this work, preparation and characterization of a novel nanocomposite containing bismuth oxide (Bi2O3) nanoparticles and multiwalled carbon nanotubes (MWCNTs) was presented. Powder X-ray diffraction (XRD) studies revealed that as-synthesized Bi2O3 nanoparticles are crystalline and belong to ?-phase with monoclinic symmetry. Field emission scanning electron microscopy (FESEM) study results showed that the size of Bi2O3 nanoparticles is 50nm. Energy-dispersive X-ray

  19. Etched ion tracks in silicon oxide and silicon oxynitride as charge injection or extraction channels for novel electronic structures

    Microsoft Academic Search

    D. Fink; A. V. Petrov; K. Hoppe; W. R. Fahrner; R. M. Papaleo; A. S. Berdinsky; A. Chandra; A. Chemseddine; A. Zrineh; A. Biswas; F. Faupel; L. T. Chadderton

    2004-01-01

    The impact of swift heavy ions onto silicon oxide and silicon oxynitride on silicon creates etchable tracks in these insulators. After their etching and filling-up with highly resistive matter, these nanometric pores can be used as charge extraction or injection paths towards the conducting channel in the underlying silicon. In this way, a novel family of electronic structures has been

  20. Oxynitride gate dielectric prepared by thermal oxidation of low-pressure chemical vapor deposition silicon-rich silicon nitride

    Microsoft Academic Search

    Jackie Chan; Hei Wong; M. C. Poon; C. W. Kok

    2003-01-01

    Thin oxynitride gate dielectric films were prepared by thermal oxidation of low-pressure chemical vapor deposition silicon-rich silicon nitride at temperature ranging 850–1050 °C. X-ray photoelectron spectroscopy results indicate that the conversion of the as-deposited silicon nitride into oxynitride with different composition or oxide is feasible and the process is governed by the oxidation temperature. For sample oxidized at 1050 °C

  1. Gradual oxidation of stain etched porous silicon nanostructures applied to silicon-based solar cells

    Microsoft Academic Search

    B. González-Díaz; R. Guerrero-Lemus; J. Méndez-Ramos; B. Díaz-Herrera; V. D. Rodríguez

    2009-01-01

    This work describes the photoluminescence (PL) and morphology of stain etched porous silicon nanostructures (PSN) submitted to a gradual oxidation by immersion in a HNO3 boiling point solution and applied to solar cells. The gradual oxidation passivates the extremely reactant fresh porous surface and softens the porous structure for an adequate placement of the metallic contact on top. The pore

  2. Carbon nanotube network-silicon oxide non-volatile switches.

    PubMed

    Liao, Albert D; Araujo, Paulo T; Xu, Runjie; Dresselhaus, Mildred S

    2014-01-01

    The integration of carbon nanotubes with silicon is important for their incorporation into next-generation nano-electronics. Here we demonstrate a non-volatile switch that utilizes carbon nanotube networks to electrically contact a conductive nanocrystal silicon filament in silicon dioxide. We form this device by biasing a nanotube network until it physically breaks in vacuum, creating the conductive silicon filament connected across a small nano-gap. From Raman spectroscopy, we observe coalescence of nanotubes during breakdown, which stabilizes the system to form very small gaps in the network~15?nm. We report that carbon nanotubes themselves are involved in switching the device to a high resistive state. Calculations reveal that this switching event occurs at ~600?°C, the temperature associated with the oxidation of nanotubes. Therefore, we propose that, in switching to a resistive state, the nanotube oxidizes by extracting oxygen from the substrate. PMID:25482919

  3. Surface chemistry dependence of native oxidation formation on silicon nanocrystals

    SciTech Connect

    Liptak, R. W.; Campbell, S. A. [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Kortshagen, U. [Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2009-09-15

    The growth of silicon oxide on bare and SF{sub 6}-etched silicon nanocrystals (Si-NCs), which were synthesized by an all gas phase approach, was investigated by examining the surface chemistry and optical properties of the NCs over time. Consistent with previous work in the low temperature oxidation of silicon, the oxidation follows the Cabrera-Mott mechanism, and the measured data are well fitted to the Elovich equation. The use of the SF{sub 6} plasma is found to reduce the surface Si-H bond density and dramatically increase the monolayer growth rate. This is believed to be due to the much larger volatility of Si-F bonds compared to Si-H bonds on the surface of the NC.

  4. Enhancement of radiation effects by bismuth oxide nanoparticles for kilovoltage x-ray beams: A dosimetric study using a novel multi-compartment 3D radiochromic dosimeter

    NASA Astrophysics Data System (ADS)

    Alqathami, M.; Blencowe, A.; Yeo, U. J.; Franich, R.; Doran, S.; Qiao, G.; Geso, M.

    2013-06-01

    The aim of this study is to present the first experimental validation and quantification of the dose enhancement capability of bismuth oxide nanoparticles (Bi2O3-Nps). A recently introduced multi-compartment 3D radiochromic dosimeter for measuring radiation dose enhancement produced from the interaction of X-rays with metal nanoparticles was employed to investigate the 3D spatial distribution of ionizing radiation dose deposition. Dose-enhancement factor for the dosimeters doped with Bi2O3-NPs was ~1.9 for both spectrophotometry and optical CT analyses. Our results suggest that bismuth-based nanomaterials are efficient dose enhancing agents and have great potential for application in clinical radiotherapy.

  5. Bismuth nanoparticles electrooxidation: theory and experiment

    Microsoft Academic Search

    Kh. Z. Brainina; Leonid Gdalievich Galperin; Ludmila Aleksandrovna Piankova; Natalia Yurievna Stozhko; Aidar Marksovich Myrzakaev; Olga Romanovna Timoshenkova

    The article presents the findings of microscopic and electrochemical studies of electrooxidation of bismuth particle of varying\\u000a sizes. Bismuth particles were immobilized on the surface of indifferent carbon containing screen-printed electrodes. The calculations\\u000a and experimental studies demonstrated that the transition from macroparticles to nanoparticles caused a shift of the maximum\\u000a current potential of bismuth oxidation into the area with more

  6. Synthesis, Characterization, and Thermoelectric Properties of Electrospun Boron-Doped Barium-Stabilized Bismuth-Cobalt Oxide Nanoceramics

    NASA Astrophysics Data System (ADS)

    Çinar, Emre; Koçyi?it, Serhat; Aytimur, Arda; Uslu, ?brahim; Akdemir, Ahmet

    2014-08-01

    In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by the polymeric precursor technique. The powders were characterized by X-ray diffraction, scanning electron microscopy, and the physical properties measurement system. The X-ray diffraction results showed that these patterns have mixture of two phases as face-centered cubic and body-centered cubic. Values of the crystallite size, the dislocation density, and the microstrain were calculated by the Scherrer equation. According to these values, the crystallite size decreased from 60 to 51 nm with the boron addition in the boron-undoped and boron-doped samples, respectively. The scanning electron microscope results showed that nanograins are rarely seen in the boron-undoped samples, but nanograins turn into needle-like and layered structures with boron addition. The diameters distribution of nanofibers was calculated. The average diameter of the boron-doped sample is smaller than the boron-undoped sample. The physical properties measurement system values showed that the electrical and thermal conductivity, the Seebeck coefficient, and the figure of merit increased with the temperature rise for both samples. The boron-doping effect increased the electrical and thermal conductivity, decreased the Seebeck coefficient, and decreased the figure of merit.

  7. Hole-blocking titanium-oxide/silicon heterojunction and its application to photovoltaics

    E-print Network

    Hole-blocking titanium-oxide/silicon heterojunction and its application to photovoltaics Sushobhan-bandgap semiconducting heterojunctions on silicon. Here, we present a wide-bandgap heterojunction--between titanium oxide and crystalline silicon--where the titanium oxide is deposited via a metal-organic chemical vapor deposition

  8. Structural and electrochemical evaluation of bismuth doped lithium titanium oxides for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Subburaj, T.; Prasanna, K.; Kim, Ki Jae; Ilango, P. Robert; Jo, Yong Nam; Lee, Chang Woo

    2015-04-01

    Micro-sized Li4Ti5-xBixO12 (0 ? x ? 0.15) materials are synthesized using a simple solid state method in air. The structural, morphological, and electrochemical characteristics of Bi-doped lithium titanates and pristine samples are methodically analyzed by X-ray diffraction (XRD), Raman spectroscopy, field emission-scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The XRD and Raman spectroscopy results demonstrate that bismuth-doping do not alter the spinel structure and good crystalline materials are synthesized. The FE-SEM images show that all samples possess the same morphological characteristics, with a particle size distribution of 0.5-1 ?m. The electrochemical cycling testing reveals that the Li4Ti4.9Bi0.10O12 sample exhibits discharge capacities of 205.4 mAh g-1, 160.8 mAh g-1, and 135.4 mAh g-1 after 50 cycles at 1C, 5C, and 10C-rates, respectively. The differential capacity curves suggest that the Li4Ti4.9Bi0.10O12 sample has a weaker polarization effect than the other samples. The EIS measurements imply that the Li4Ti4.9Bi0.10O12 sample possesses a high electronic conductivity and lithium ion diffusivity, which demonstrate that this new Li4Ti4.9Bi0.10O12 material would be a good candidate as an anode for lithium ion batteries.

  9. Oxide mediated epitaxy of CoSi2 on silicon

    NASA Astrophysics Data System (ADS)

    Tung, R. T.

    1996-06-01

    Uniform, single-crystal CoSi2 layers have been grown on Si by the technique of oxide mediated epitaxy (OME). Deposition of a thin layer of cobalt (1-3 nm) onto surfaces covered with a thin silicon oxide layer and annealing at 500-700 °C led to the growth of epitaxial, essentially uniform, CoSi2 layers on the (100), (110), and (111) surfaces of Si. The nucleation and growth of silicide apparently occurred subsurface, leaving the silicon oxide layer largely on the surface of the silicide after the growth. On all surfaces, thicker (10-30 nm), excellent quality, CoSi2 single-crystal thin films have been grown by repeated growth sequences. Experimental results are presented along with a discussion on the possible roles played by the thin oxide layer in promoting the epitaxial growth of silicide.

  10. Gated twin-bit silicon–oxide–nitride–oxide–silicon NAND flash memory for high-density nonvolatile memory

    NASA Astrophysics Data System (ADS)

    Kim, Yoon; Shim, Won Bo; Park, Byung-Gook

    2015-06-01

    In this paper, we report the fabrication and analysis of the gated twin-bit NAND flash memory with a nitride charge-trapping layer. This device is based on the recessed channel structure, and it has an additional cut-off gate that enables 2-bit operation. Therefore, the density of the array can be doubled without any difficulty in patterning. The fabrication method for gated twin-bit (GTB) silicon–oxide–nitride–oxide–silicon (SONOS) memories and their electrical characteristics are described in this paper. Program/erase characteristics are observed and the 2-bit operation is verified by the forward–reverse reading scheme.

  11. Effects of silicone pretreatment on oxidative hair damage

    Microsoft Academic Search

    MARIANNE D. BERTHIAUME; JAMES H. MERRIFIELD

    Synopsis A high-viscosity, high-amine-content silicone fluid has been found to provide significant conditioning properties. Application of this material as a pretreatment provides protection against the damage caused by bleaching and oxidative dyeing as observed by scanning electron microscopy (SEM) and combing force studies. This product does not interfere with the bleaching or oxidative dyeing processes when used as a pretreatment

  12. Bismuth(III) and copper(II) oxides as catalysts for the electro-oxidation of organic compounds

    Microsoft Academic Search

    Thomas C. Franklin; K. H. Lee; E. Manlangit; R. Nnodimele

    1996-01-01

    It was shown that copper(II) oxide bound to the anode with polystyrene containing a cationic surfactant acted as a catalyst for the oxidation of organic compounds in aqueous systems in a manner similar to powdered copper oxide suspended in aqueous systems containing the organic compounds and the cationic surfactant. Voltammetric measurements made with these electrodes were reproducible over an extended

  13. Y-Ba-Cu-O superconducting film on oxidized silicon

    SciTech Connect

    Gupta, R.P.; Khokle, W.S.; Dubey, R.C.; Singhal, S.; Nagpal, K.C.; Rao, G.S.T.; Jain, J.D.

    1988-06-06

    We report thick superconducting films of Y-Ba-Cu-O on oxidized silicon substrates. The critical temperatures for onset and zero resistance are 96 and 77 K, respectively. X-ray diffraction analysis predicts 1, 2, 3 composition and orthorhombic phase of the film.

  14. Deposition and Properties of Bismuth Strontium Calcium Copper Oxide Superconducting Thin Films

    NASA Astrophysics Data System (ADS)

    Dimeo, Frank, Jr.

    1995-01-01

    The deposition of superconducting Bi-Sr-Ca-Cu -O thin films has been investigated using metalorganic chemical vapor deposition. For this purpose, a low pressure growth system was designed and built. Using the precursors, triphenyl bismuth, copper acetylacetonate, strontium hexafluoroacetylacetonate tetraglyme, and calcium hexafluoroacetylacetonate tetraglyme, superconducting epitaxial rm Bi_2Sr _2CaCu_2O_8 thin films have been deposited in situ. The addition of H_2 O to the oxygen reactant gas was necessary for the formation of the rm Bi_2Sr_2CaCu _2O_8 phase. The measured stability range for the deposition of the 2212 phase was between temperatures of 820 and 860^circC, at oxygen partial pressures greater than 9 Torr. X-ray diffraction (theta/2 theta and phi scan) measurements indicated that the films were epitaxial to the single crystal substrates LaAlO_3, NdGaO_3, and SrTiO _3. The surface morphology was investigated with SEM and AFM, and consisted of a dense platelet morphology. Individual platelets were several microns in size, and had surface roughnesses between 20-100A. There were significant step edges between platelets, however, ranging from 200-1000A. rm Bi_2Sr_2CaCu_2O _8 films on LaAlO_3 had T_{rm c}'s as high as 90 K, and J_{rm c} 's as high as rm1.9times10^7 A/cm^2 at 5 K. Films on NdGaO _3 had degraded superconducting properties due to contamination from the substrate and suffered from microcracking due to the lattice mismatch. A method for tailoring the electronic properties of the films through the substitution of Y for Ca was also developed, using yttrium dipivaloylmethanate as the source. With increasing Y content, the T_{rm c} was depressed. Insulating films were produced for Y = 0.54 formula units. The resistivity and thermopower behavior as a function of temperature and Y content was studied. The low temperature, T < 50 K, resistivity of insulating samples was found to exhibit variable range hopping behavior of the form, rho~ T^{b}exp(BT^ {-alpha}). The high temperature, T > 100, resistive behavior was analyzed using a narrow band model, consisting of a region of delocalized states surrounded by tails of localized states. This model predicted the resistive behavior of both insulating and superconducting films quite well. It was also found to predict the thermopower data for the superconducting films, although there was a discrepancy between the fitting parameters from the resistivity and those from the thermopower.

  15. Oxidation of Silicon in TCA/O 2 Ambients Mitra Navi and Scott T. Dunham

    E-print Network

    Dunham, Scott

    Oxidation of Silicon in TCA/O 2 Ambients Mitra Navi and Scott T. Dunham Electrical, Computer chlorine incorporation, film growth kinetics and oxidation enhanced diffusion of phosphorus during oxidation in TCA (1,1,1­Trichloroethane)/O 2 ambients. Silicon wafers were oxidized at 900 and 1000 ffi C

  16. First-principles study on the electronic structure of bismuth transition-metal oxides

    Microsoft Academic Search

    T. Shishidou; N. Mikamo; Y. Uratani; F. Ishii; T. Oguchi

    2004-01-01

    The electronic structure, magnetic and electric properties, and lattice stability of multiferroic BiMnO3 as a typical system in perovskite Bi transition-metal oxides (BiMO3) are studied from first principles. It is demonstrated theoretically for the first time that the orbital ordering within the Mn eg orbitals is actually realized in BiMnO3, being consistent with crystallographic data, and plays a crucial role

  17. Floating low-temperature radio-frequency plasma oxidation of polycrystalline silicon-germanium

    E-print Network

    Floating low-temperature radio-frequency plasma oxidation of polycrystalline silicon silicon­germanium poly-SiGe is more preferable than polycrystalline silicon poly-Si in AMLCD because displays. However, low temperature oxide is prone to have defects at the SiO2 /polycrystalline

  18. Oxidation and roughening of silicon during annealing in a rapid thermal processing chamber

    Microsoft Academic Search

    B. Mohadjeri; M. R. Baklanov; E. Kondoh; K. Maex

    1998-01-01

    Silicon wafers were annealed at 1100 °C in nitrogen flowing ambient, using a conventional rapid thermal processing system operating at atmospheric pressure. Subsequently, silicon oxidation and the resulting surface morphology following chemical etching of the oxide film were studied. According to atomic force microscopy analysis, a significant amount of roughening occurs on the silicon surface after the high temperature anneal

  19. Quantitative determination of the clustered silicon concentration in substoichiometric silicon oxide layer

    SciTech Connect

    Spinella, Corrado; Bongiorno, Corrado; Nicotra, Giuseppe; Rimini, Emanuele; Muscara, Anna; Coffa, Salvo [Istituto per la Microelettronica e Microsistemi-CNR, Stradale Primosole 50, I-95121 Catania (Italy); STMicroelectronics, Stradale Primosole 50, I95121 Catania (Italy)

    2005-07-25

    We present an analytical methodology, based on electron energy loss spectroscopy (EELS) and energy-filtered transmission electron microscopy, which allows us to quantify the clustered silicon concentration in annealed substoichiometric silicon oxide layers, deposited by plasma-enhanced chemical vapor deposition. The clustered Si volume fraction was deduced from a fit to the experimental EELS spectrum using a theoretical description proposed to calculate the dielectric function of a system of spherical particles of equal radii, located at random in a host material. The methodology allowed us to demonstrate that the clustered Si concentration is only one half of the excess Si concentration dissolved in the layer.

  20. Tantalum oxide and niobium oxide antireflection films in silicon solar cells

    Microsoft Academic Search

    A. G. Revesz; J. F. Allison; J. H. Reynolds

    1976-01-01

    A detailed description is presented of the preparation and properties of noncrystalline Ta2O5 and, to a lesser degree, Nb2O5 films on silicon in terms of their application as antireflection (AR) coating for silicon solar cells. It is found that thermal oxidation of Ta and Nb films deposited in vacuum on Si substrate results in noncrystalline Ta2O5 and Nb2O5 films with

  1. Crystalline zirconia oxide on silicon as alternative gate dielectrics

    NASA Astrophysics Data System (ADS)

    Wang, S. J.; Ong, C. K.; Xu, S. Y.; Chen, P.; Tjiu, W. C.; Chai, J. W.; Huan, A. C. H.; Yoo, W. J.; Lim, J. S.; Feng, W.; Choi, W. K.

    2001-03-01

    Epitaxial crystalline yittria-stabilized zirconia (YSZ) oxide films were grown on silicon wafers by the laser molecular beam epitaxy technique. The interface of crystalline YSZ film in contact with silicon was found to be atomically sharp and commensurately crystallized without an amorphous layer. An x-ray photoelectron spectroscopy depth profile and transmission electron microscopy investigation showed that no SiO2 formed at the interface. For a film with electrical equivalent oxide thickness (teox) 14.6 Å, the leakage current is about 1.1×10-3 A/cm2 at 1 V bias voltage. The hysteresis and interface state density in this film are measured to be less than 10 mV and 2.0×1011eV-1 cm-2, respectively.

  2. Influence of substrate geometry on the distribution and stress on Ge nanocrystals in silicon oxide matrix

    SciTech Connect

    Zheng, F. [Microelectronics Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 1176576 (Singapore); Choi, W. K. [Microelectronics Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 1176576 (Singapore); Advanced Materials for Micro- and Nano-Systems Programme, Singapore-MIT Alliance, National University of Singapore, 4 Engineering Drive 3, Singapore 1176576 (Singapore); Liew, T. H. [Advanced Materials for Micro- and Nano-Systems Programme, Singapore-MIT Alliance, National University of Singapore, 4 Engineering Drive 3, Singapore 1176576 (Singapore)

    2008-10-15

    Synthesis of germanium (Ge) nanocrystals embedded in silicon oxide matrix was carried out on cosputtered Ge plus silicon oxide films deposited on the surface of silicon (Si) wafer etched with V- or U-grooves. The V- or U-grooves were fabricated via the laser interference lithography technique. We found that the substrate geometry has a significant influence on the distribution of the Ge nanocrystals in the silicon oxide matrix. The variation in the distribution of the nanocrystals in the silicon oxide matrix may be due to defective oxide regions caused by sputter deposited silicon oxide film on the V- or U-grooves or may also be related to the different strain fields in the oxide layer.

  3. Oxidation of silicon-germanium alloys. I. An experimental study

    NASA Astrophysics Data System (ADS)

    Hellberg, P.-E.; Zhang, S.-L.; d'Heurle, F. M.; Petersson, C. S.

    1997-12-01

    The oxidation of polycrystalline SixGe1-x films with different compositions (i.e., different values of x) is carried out in pyrogenic steam at 800 °C for various lengths of time. It is found that the oxidation is enhanced by the presence of germanium and that the enhancement effect is more pronounced for the films richer in germanium. A mixed oxide in the form of either (Si,Ge)O2 or SiO2-GeO2 is found at the sample surface if the initial SixGe1-x contains more than 50% of germanium. However, a surface silicon cap layer of about 14 nm is found to have a significant impact on the oxidation of the Si0.5Ge0.5 films; it leads to the growth of about 115-nm-thick SiO2 which is about four times that of the SiO2 resulting from the oxidation of the cap layer itself. On the SixGe1-x films with only 30% of germanium, the SiO2 continues to grow after oxidation for 180 min resulting in 233-nm-thick SiO2 which is about 2.4 times greater than the SiO2 grown on <100> silicon substrates. Rejection of germanium results in piling up of germanium at the interface between the growing SiO2 and the remaining SixGe1-x. Substantial interdiffusion of silicon and germanium takes place in the remaining SixGe1-x. The experimental results are discussed in terms of thermodynamics and kinetics.

  4. Nickel-silicide phase effects on flatband voltage shift and equivalent oxide thickness decrease of hafnium silicon oxynitride metal-silicon-oxide capacitors

    Microsoft Academic Search

    Chang Yong Kang; Pat Lysaght; Rino Choi; Byoung Hun Lee; Se Jong Rhee; Chang Hwan Choi; M. S. Akbar; Jack C. Lee

    2005-01-01

    This Letter reports the nickel-silicide phase effects on the electrical characteristics of high-k and silicon dioxide (SiO2) metal-oxide-semiconductor devices. It was found that the silicon-deficient nickel-silicided gate electrode on the hafnium silicon oxynitride (HfSiON) led to a positive flatband voltage (Vfb) shift and a reduction in the equivalent oxide thickness (EOT). However, negligible Vfb shift and EOT decrease were observed

  5. Boron removal from metallurgical grade silicon by oxidizing refining

    Microsoft Academic Search

    Ji-jun WU; Wen-hui MA; Bin YANG; Yong-nian DAI; K. MORITA

    2009-01-01

    A purification process was developed to remove impurity element boron from the metallurgical grade silicon by the electric arc furnace refining. The thermodynamic equilibria calculation and experiment to remove boron in the oxidizing atmosphere were performed and analyzed. Boron is removed as the gaseous species BxOy and BxHzOy in O2 and H2O-O2 atmosphere respectively. The equilibrium pressure of BxHzOy is

  6. Growth of niobium oxide films on single-crystal silicon

    Microsoft Academic Search

    V. A. Logacheva; N. A. Divakova; Yu. A. Tikhonova; E. A. Dolgopolova; A. M. Khoviv

    2007-01-01

    200-nm-thick niobium films grown on single-crystal silicon wafers by magnetron sputtering have been oxidized by annealing\\u000a in flowing oxygen. X-ray diffraction examination revealed the metal-like phase Nb6O in the as-deposited films. Annealing in flowing oxygen for 1 h led to the formation of tetragonal NbO2 at 570 K and hexagonal Nb2O5 at temperatures above 770 K. The grain size and

  7. Niobium nitride Josephson tunnel junctions with oxidized amorphous silicon barriers

    Microsoft Academic Search

    F. Shinoki; A. Shoji; S. Kosaka; S. Takada; H. Hayakawa

    1981-01-01

    High-quality NbN\\/NbN Josephson tunnel junctions have been fabricated by rf sputtering. Tunneling barriers are formed by oxidizing amorphous silicon films produced with rf glow discharge deposition. For patterning the base and counter electrode, sputtered ZnO films are employed as a resist mask. The juncitons are found to have large gaps (2?NbN) =4.4 mV), to have low leakage current, and to

  8. Study on precipitations of fluorine-doped silicon oxide

    Microsoft Academic Search

    Jun Wu; Ying-Lang Wang; Chuan-Pu Liu; Shih-Chieh Chang; Cheng-Tzu Kuo; Chyung Ay

    2004-01-01

    Precipitation on fluorine-doped silicon oxide film (SiOF) was observed while exposure to air for a prolonged period of time (>4 h). Most of the precipitates are less than 1 ?m and clustered at wafer center. Under SEM view, the precipitation shows hexagonal shape, and mainly composed of Si and O. SIMS analysis showed that SiOF films without F precipitates showed

  9. Low Dielectric Constant Interlayer Using Fluorine-Doped Silicon Oxide

    Microsoft Academic Search

    Takashi Usami; Kimiaki Shimokawa; Masaki Yoshimaru

    1994-01-01

    A new interlayer dielectric film using fluorine-doped silicon oxide (SiOF) for multilevel interconnection of very large scale integration (VLSI) has been fabricated. The film is deposited by a simple technique, which is hexafluoroethane ( C2F6) addition to conventional tetraethoxysilane (TEOS)-based plasma-enhanced chemical vapor deposition (PE-CVD). Si F bond formation in the film is detected by chemical bonding structural studies using

  10. Silicon dry oxidation kinetics at low temperature in the nanometric range: modeling and experiment

    E-print Network

    Paris-Sud XI, Université de

    APS/xxxxx Silicon dry oxidation kinetics at low temperature in the nanometric range: modeling. INTRODUCTION An important challenge imposed by CMOS downscaling is the growth of ultra-thin ox- ides of silicon

  11. Effect of thermal annealing on structure and photoluminescence properties of silicon-rich silicon oxides

    NASA Astrophysics Data System (ADS)

    Zhigunov, D. M.; Seminogov, V. N.; Timoshenko, V. Yu.; Sokolov, V. I.; Glebov, V. N.; Malyutin, A. M.; Maslova, N. E.; Shalygina, O. A.; Dyakov, S. A.; Akhmanov, A. S.; Panchenko, V. Ya.; Kashkarov, P. K.

    2009-05-01

    The structure and optical properties of thermally annealed silicon-rich silicon oxide (SRSO) films are investigated by means of transmission electron microscopy (TEM), photoluminescence (PL), infrared (IR) and Raman spectroscopy. The samples were prepared by the reactive evaporation of SiO powder with subsequent deposition of SiO x ( x?1) thin films on quartz or sapphire substrates, followed by thermal annealing at temperatures from 350 to 1200 °C. Si nanocrystals formation in SRSO films was detected by TEM, Raman and PL spectroscopy at annealing temperatures above 950 °C. The volume fraction of the silicon phase in SRSO films was obtained from IR measurements, which, together with PL and Raman spectroscopy data, allowed us to propose a model of SRSO structure transformations under thermal annealing.

  12. Raman scattering from confined acoustic phonons of silicon nanocrystals in silicon oxide matrix

    NASA Astrophysics Data System (ADS)

    Zatryb, G.; Wilson, P. R. J.; Wojcik, J.; Misiewicz, J.; Mascher, P.; Podhorodecki, A.

    2015-06-01

    In this work, silicon-rich silicon oxide films of different stoichiometry were annealed at high temperatures in order to obtain silicon nanocrystals embedded in silica. The low-frequency Raman scattering has been observed and related to acoustic phonons confined in these nanocrystals. It has been found that this scattering consists of two modes: one at a lower frequency and one at a higher frequency. The depolarization ratios for these modes were determined, showing that the lower frequency mode is depolarized and the higher frequency mode is polarized. It has been also found that under specific conditions of film preparation the product of mode frequency and nanocrystal diameter is scale invariant. Finally, it has been shown that the confined acoustic phonon frequencies do not simply depend on the nanocrystal size alone, but also on the Si concentration in the film itself. This effect has been ascribed to the accelerated nucleation and enhanced crystallization occurring in the films deposited with higher Si content.

  13. Green light emission from terbium doped silicon rich silicon oxide films obtained by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Podhorodecki, A.; Zatryb, G.; Misiewicz, J.; Wojcik, J.; Wilson, P. R. J.; Mascher, P.

    2012-11-01

    The effect of silicon concentration and annealing temperature on terbium luminescence was investigated for thin silicon rich silicon oxide films. The structures were deposited by means of plasma enhanced chemical vapor deposition. The structural properties of these films were investigated by Rutherford backscattering spectrometry, transmission electron microscopy and Raman scattering. The optical properties were investigated by means of photoluminescence and photoluminescence decay spectroscopy. It was found that both the silicon concentration in the film and the annealing temperature have a strong impact on the terbium emission intensity. In this paper, we present a detailed discussion of these issues and determine the optimal silicon concentration and annealing temperature.

  14. Green light emission from terbium doped silicon rich silicon oxide films obtained by plasma enhanced chemical vapor deposition.

    PubMed

    Podhorodecki, A; Zatryb, G; Misiewicz, J; Wojcik, J; Wilson, P R J; Mascher, P

    2012-11-30

    The effect of silicon concentration and annealing temperature on terbium luminescence was investigated for thin silicon rich silicon oxide films. The structures were deposited by means of plasma enhanced chemical vapor deposition. The structural properties of these films were investigated by Rutherford backscattering spectrometry, transmission electron microscopy and Raman scattering. The optical properties were investigated by means of photoluminescence and photoluminescence decay spectroscopy. It was found that both the silicon concentration in the film and the annealing temperature have a strong impact on the terbium emission intensity. In this paper, we present a detailed discussion of these issues and determine the optimal silicon concentration and annealing temperature. PMID:23110801

  15. FT-ICR Study of Reaction Induced Fragmentation of Silicon Clusters with Nitric Oxide

    E-print Network

    Maruyama, Shigeo

    FT-ICR Study of Reaction Induced Fragmentation of Silicon Clusters with Nitric Oxide Shigeo of small silicon cluster ions (Si n + : 20 n 29) with nitric oxide was studied by using the FT with argon, and were exposed to the reactant gas, nitric oxide, in the ICR cell. Results of reaction for all

  16. Oxidation of silicon by a low-energy ion beam: Experiment and model s. S. Todorova

    E-print Network

    Fossum, Eric R.

    Oxidation of silicon by a low-energy ion beam: Experiment and model s. S. Todorova ) and E. R) The self-limiting oxidation of silicon by a low-energy ion beam (40-120 eV) is described by an implantation-sputtering model. The thin oxide (40-50 A) is grown primarily by a surface implantation process which leads

  17. OXIDATION-INDUCED CHANGES IN MECHANICAL PROPERTIES OF SILICON NITRIDE CERAMICS

    E-print Network

    Gubicza, Jenõ

    OXIDATION-INDUCED CHANGES IN MECHANICAL PROPERTIES OF SILICON NITRIDE CERAMICS J. Gubicza, P. Arató, Hungary The effect of oxidation on the room-temperature mechanical properties of four different silicon and the hardness, the fracture toughness and the elastic modulus of the internal region (without surface oxide

  18. Determination of Silicon Point Defect Properties from Oxidation Enhanced Diffusion of Buried Layers

    E-print Network

    Dunham, Scott

    pressure chemical vapor deposition. The oxide/nitride multilayer serves as an oxidation barrier. The wafersDetermination of Silicon Point Defect Properties from Oxidation Enhanced Diffusion of Buried Layers for integrated circuit fabrication, the published calculations of silicon interstitial diffusivity vary over

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Premnath, P; Tan, B; Venkatakrishnan, K

    2015-01-01

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

  1. A new bismuth potassium nitrate oxide, Bi 1.7K 0.9O 2(NO 3) 2: Synthesis, structure, thermal behavior, and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Shenawi-Khalil, S.; Uvarov, V.; Charkin, D. O.; Goaz, A.; Popov, I.; Dolgikh, V. A.; Sasson, Y.

    2012-01-01

    We report here the first observation of a bismuth potassium nitrate Bi 1.7K 0.9O 2(NO 3) 2, obtained via thermal decomposition of bismuth and potassium nitrate mixtures. The new compound is orthorhombic, space group Immm (71), Z = 2, with a = 3.8698(7) Å, b = 3.8703(7) Å, and c = 24.1271(4) Å. Its crystal structure was refined from powder X-ray diffraction data by analogy with the mineral beyerite, Bi 2O 2Ca(CO 3) 2. The morphology and elemental composition of Bi 1.7K 0.9O 2(NO 3) 2 were characterized using scanning electron microscopy (SEM) with energy dispersive X-Ray spectroscopy (EDS). Its phase transformations upon heating and products of its thermal decomposition were studied using XRD, TGA and FTIR. At 440 °C, Bi 1.7K 0.9O 2(NO 3) 2 transforms to another basic bismuth potassium nitrate with demonstrates a very similar XRD pattern but slightly larger cell parameters. At 520 °C, the intermediate oxide nitrate decomposes into a mixture of crystalline ?-Bi 2O 3 and KNO 3. The as prepared Bi 1.7K 0.9O 2(NO 3) 2 showed lower than TiO 2 (Degussa P25) photocatalytic activity upon decomposition of a widely used model pollutant, Rhodamine B (RhB) and photooxidation of potassium iodide under UV-vis light irradiation. Interaction with potassium iodide in alkaline media resulted in formation of Bi 5O 7I.

  2. Demonstration of polarization insensitive wavelength conversion of 112Gb\\/s polarization multiplexed RZ-QPSK signals using bismuth-oxide-based nonlinear optical fiber with high SBS threshold

    Microsoft Academic Search

    Ming-Fang Huang; Jianjun Yu; Gee-Kung Chang

    2010-01-01

    Polarization insensitive wavelength conversion by employing a dual pump scheme in 112-Gb\\/s polarization-multiplexed RZ-QPSK system has been realized by using a 2-m Bismuth-Oxide-based nonlinear optical fiber (Bi-NLF) with high SBS threshold.

  3. Synthesis and structure of bismuth compounds bearing a sulfur-bridged bis(phenolato) ligand and their catalytic application to the solvent-free synthesis of propylene carbonate from CO2 and propylene oxide.

    PubMed

    Yin, Shuang-Feng; Shimada, Shigeru

    2009-03-01

    Two bismuth compounds bearing a sulfur-bridged bis(phenolato) ligand were synthesized and found to show high catalytic activity and selectivity for solvent-free synthesis of propylene carbonate from CO(2) and propylene oxide in the presence of iodide salts as co-catalysts at room temperature under 1 atm CO(2). PMID:19225661

  4. Electrical characterization of rapid thermal nitrided and re-oxidized low-pressure chemical-vapor-deposited silicon dioxide metal–oxide–silicon structures

    Microsoft Academic Search

    S. S. Ang; Y. J. Shi; W. D. Brown

    1996-01-01

    The electrical characteristics of rapid thermal nitrided and re-oxidized low-pressure chemical-vapor-deposited (LPCVD) silicon dioxide metal–oxide–silicon (MOS) structures were investigated. Both nitridation temperature and time affect the properties of the MOS structures as revealed by capacitance–voltage characteristics. Nitridation at 1000 °C for 15 s followed by re-oxidation for 60 s at 1000 °C in an oxygen\\/nitrogen ambient was found to be

  5. Effect of bismuth on microstructure of unmodified and Sr-modified Al7Si0.4Mg alloys

    Microsoft Academic Search

    S. FARAHANY; A. OURDJINI; M. H. IDRIS; L. T. THAI

    2011-01-01

    The effects of bismuth and the combination of bismuth and strontium on the eutectic silicon structure in Al-7Si-0.4Mg alloys were investigated under different solidification conditions. The results show that bismuth has a refining effect on the eutectic silicon and its refinement behavior increases with increasing Bi content up to 0.5% (mass fraction). When bismuth is added into the molten alloy

  6. Method for removing oxide contamination from silicon carbide powders

    DOEpatents

    Brynestad, J.; Bamberger, C.E.

    1984-08-01

    The described invention is directed to a method for removing oxide contamination in the form of oxygen-containing compounds such as SiO/sub 2/ and B/sub 2/O/sub 3/ from a charge of finely divided silicon carbide. The silicon carbide charge is contacted with a stream of hydrogen fluoride mixed with an inert gas carrier such as argon at a temperature in the range of about 200/sup 0/ to 650/sup 0/C. The oxides in the charge react with the heated hydrogen fluoride to form volatile gaseous fluorides such as SiF/sub 4/ and BF/sub 3/ which pass through the charge along with unreacted hydrogen fluoride and the carrier gas. Any residual gaseous reaction products and hydrogen fluoride remaining in the charge are removed by contacting the charge with the stream of inert gas which also cools the powder to room temperature. The removal of the oxygen contamination by practicing the present method provides silicon carbide powders with desirable pressing and sintering characteristics. 1 tab.

  7. Nickel oxide functionalized silicon for efficient photo-oxidation of water Namseok Park,a

    E-print Network

    Wang, Deli

    -type silicon (n-Si) as a photoanode for efficient photo-oxidation of water under neutral pH condition. The Ni thermodynamics discussed above, the other critical problem with the n-Si photoanode is associated, research focused on using the n-Si photoanode by means of altering charge transfer kinetics

  8. Optical stimulated thermoluminescence in silicon rich oxide nanostructured films

    NASA Astrophysics Data System (ADS)

    Berman-Mendoza, D.; Aceves-Mijares, M.; Piters, T.; García-Gutiérrez, R.; Ruiz-Valdez, C. F.; Ramos-Carrasco, A.; Berriel-Valdos, L. R.

    2013-11-01

    In this work, it is study thermoluminescent phenomena (TL) optically stimulated with UV radiation in Silicon Rich Oxide (SRO) nanostructured thin films. The experimental samples used were thin films of this composite deposited by Low Pressure Chemical Vapor Deposition (LPCVD) over a n-type silicon substrate, this samples were fabricated using different flow ratios of precursory gases silane and nitrous oxide R0=SiH4/N2O during the deposition and were given posterior thermal treatment which gave place to the formation of different sized nanoparticles, that are attributed to the luminescent activation mechanism in this material. The silicon excess was controlled by the ratio of the gases used in the deposition process and in this way SRO films with 12, 8 and 6% silicon excess were obtained. The glow-curves experimentally obtained were submitted to analysis using different models in order to obtain important thermoluminescent parameters. The luminescence spectra of SRO show two wavelength regions of emission; one in the blue part and one in the red part of the emission spectrum. The emission in the blue part is related to defects in the SiO lattice. About the origin of the red luminescence there is still a controversy. One model assumes that the red luminescence stems from Si nano particles and another model assumes that defects at the interface of SiO bulk with the Si nano particle are responsible for the red luminescence. Finally is intended to provide favorable conditions for the development of a UV dosimeter with this material.

  9. Oxidation Behavior of Carbon Fiber Reinforced Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    Valentin, Victor M.

    1995-01-01

    Carbon fiber reinforced Silicon Carbide (C-SiC) composites offer high strength at high temperatures and good oxidation resistance. However, these composites present some matrix microcracks which allow the path of oxygen to the fiber. The aim of this research was to study the effectiveness of a new Silicon Carbide (SiC) coating developed by DUPONT-LANXIDE to enhance the oxidation resistance of C-SiC composites. A thermogravimetric analysis was used to determine the oxidation rate of the samples at different temperatures and pressures. The Dupont coat proved to be a good protection for the SiC matrix at temperatures lower than 1240 C at low and high pressures. On the other hand, at temperatures above 1340 C the Dupont coat did not seem to give good protection to the composite fiber and matrix. Even though some results of the tests have been discussed, because of time restraints, only a small portion of the desired tests could be completed. Therefore, no major conclusions or results about the effectiveness of the coat are available at this time.

  10. Extraction and separation of bismuth(III).

    PubMed

    Langade, A D; Shinde, V M

    1981-10-01

    Separation of bismuth from beryllium, lead, iron(III), indium, scandium, lanthanum, antimony(III), zirconium, titanium, thorium, vanadium(V), molybdenum(VI), uranium (VI) and chromium(VI) is achieved by selective extraction of bismuth from 0.1M sodium salicylate solution (adjusted to pH 7) into mesityl oxide (MeO). The extracted species is Bi (HOC(6)H(4)COO)(3).3MeO. The results are accurate within +/- 0.5%, with a standard deviation of 0.8%. The separation and determination of bismuth takes only 15 min. PMID:18963000

  11. Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation

    SciTech Connect

    Ryckman, Judson D.; Reed, Robert A.; Weller, Robert A.; Fleetwood, D. M.; Weiss, S. M. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States)

    2010-12-01

    We report the observation of enhanced oxidation on silicon and porous silicon samples exposed in air ambient to high-dose-rate 10 keV x-ray radiation at room temperature. The evolution of the radiation-induced oxide growth is monitored by ellipsometry and interferometric reflectance spectroscopy. Fourier transform infrared (FTIR) spectroscopy shows the emergence of Si-O-Si stretching modes and corresponding suppression of SiH{sub x} and Si-Si modes in the porous silicon samples. The radiation response depends strongly on initial native oxide thickness and Si-H surface species. The enhanced oxidation mechanism is attributed to photoinduced oxidation processes wherein energetic photons are used to dissociate molecular oxygen and promote the formation of more reactive oxygen species.

  12. Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation

    NASA Astrophysics Data System (ADS)

    Ryckman, Judson D.; Reed, Robert A.; Weller, Robert A.; Fleetwood, D. M.; Weiss, S. M.

    2010-12-01

    We report the observation of enhanced oxidation on silicon and porous silicon samples exposed in air ambient to high-dose-rate 10 keV x-ray radiation at room temperature. The evolution of the radiation-induced oxide growth is monitored by ellipsometry and interferometric reflectance spectroscopy. Fourier transform infrared (FTIR) spectroscopy shows the emergence of Si-O-Si stretching modes and corresponding suppression of SiHx and Si-Si modes in the porous silicon samples. The radiation response depends strongly on initial native oxide thickness and Si-H surface species. The enhanced oxidation mechanism is attributed to photoinduced oxidation processes wherein energetic photons are used to dissociate molecular oxygen and promote the formation of more reactive oxygen species.

  13. Electrical characterization of low-pressure chemical-vapor-deposited silicon dioxide metal-oxide-silicon structures

    Microsoft Academic Search

    S. S. Ang; Y. J. Shi; W. D. Brown

    1993-01-01

    The electrical characteristics of as-deposited and oxygen-annealed low-pressure chemical-vapor-deposited (LPCVD) silicon dioxide (SiO2) metal-oxide-silicon (MOS) structures were investigated. As-deposited LPCVD SiO2 MOS structures exhibit a high oxide fixed charge density in the mid-1011 cm?2 and an interface state density in the low-1011 cm?2 eV?1 due to the large number of oxygen and silicon dangling bonds. A low electron barrier height

  14. Study of the processes of carbonization and oxidation of porous silicon by Raman and IR spectroscopy

    SciTech Connect

    Vasin, A. V.; Okholin, P. N.; Verovsky, I. N.; Nazarov, A. N.; Lysenko, V. S. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine); Kholostov, K. I., E-mail: kholostov@gmail.com; Bondarenko, V. P. [Belarusian State University of Informatics and Radio Electronics (Belarus); Ishikawa, Y. [Japan Fine Ceramics Center (Japan)

    2011-03-15

    Porous silicon layers were produced by electrochemical etching of single-crystal silicon wafers with the resistivity 10 {Omega} cm in the aqueous-alcohol solution of hydrofluoric acid. Raman spectroscopy and infrared absorption spectroscopy are used to study the processes of interaction of porous silicon with undiluted acetylene at low temperatures and the processes of oxidation of carbonized porous silicon by water vapors. It is established that, even at the temperature 550 Degree-Sign C, the silicon-carbon bonds are formed at the pore surface and the graphite-like carbon condensate emerges. It is shown that the carbon condensate inhibits oxidation of porous silicon by water vapors and contributes to quenching of white photoluminescence in the oxidized carbonized porous silicon nanocomposite layer.

  15. Three-dimensional integration of metal-oxide-semiconductor transistor with subterranean photonics in silicon

    Microsoft Academic Search

    Tejaswi Indukuri; Prakash Koonath; Bahram Jalali

    2006-01-01

    Monolithic integration of photonics and electronics has been achieved in silicon by three-dimensionally integrating metal-oxide-semiconductor field-effect transistors and waveguide-coupled microdisk resonators. Implantation of oxygen ions into a silicon-on-insulator substrate with a patterned thermal oxide mask followed by a high temperature anneal was utilized to realize the buried photonic structures. This results in the formation of vertically stacked silicon layers separated

  16. Single crystal ternary oxide ferroelectric integration with Silicon

    NASA Astrophysics Data System (ADS)

    Bakaul, Saidur; Serrao, Claudy; Youun, Long; Khan, Asif; Salahuddin, Sayeef

    2015-03-01

    Integrating single crystal, ternary oxide ferroelectric thin film with Silicon or other arbitrary substrates has been a holy grail for the researchers since the inception of microelectronics industry. The key motivation is that adding ferroelectric materials to existing electronic devices could bring into new functionality, physics and performance improvement such as non-volatility of information, negative capacitance effect and lowering sub-threshold swing of field effect transistor (FET) below 60 mV/decade in FET [Salahuddin, S, Datta, S. Nano Lett. 8, 405(2008)]. However, fabrication of single crystal ferroelectric thin film demands stringent conditions such as lattice matched single crystal substrate and high processing temperature which are incompatible with Silicon. Here we report on successful integration of PbZr0.2Ti0.8O3 in single crystal form with by using a layer transfer method. The lattice structure, surface morphology, piezoelectric coefficient d33, dielectric constant, ferroelectric domain switching and spontaneous and remnant polarization of the transferred PZT are as good as these characteristics of the best PZT films grown by pulsed laser deposition on lattice matched oxide substrates. We also demonstrate Si based, FE gate controlled FET devices.

  17. Effect of organic contaminants on the oxidation kinetics of silicon at room temperature

    NASA Astrophysics Data System (ADS)

    Licciardello, Antonino; Puglisi, Orazio; Pignataro, Salvatore

    1986-01-01

    The oxidation kinetics of HF-etched n- and p-doped silicon in air at room temperature have been studied by electron spectroscopy for chemical analysis. No great differences have been found between the n- and p-type oxidation kinetics at the low doping level of the studied samples. The rate of oxide growth on the HF-etched surface is much lower than that on a silicon surface obtained by fracture in air of a silicon monocrystal. The behavior of a silicon sample fractured in de-ionized water and then oxidized in air at room temperature is intermediate. The above findings have been interpreted on the basis of surface reactions involving the plasticizers of the HF and water containers. These reactions produce carbon-rich hydrophobic surfaces which retard the silicon oxide growth. A mechanism for the involved surface reactions is proposed.

  18. Oxidation effects on graded porous silicon anti-reflection coatings

    E-print Network

    Thøgersen, Annett; Marstein, Erik S; 10.1149/2.jes113659

    2012-01-01

    Efficient anti-reflection coatings (ARC) improve the light collection and thereby increase the current output of solar cells. By simple electrochemical etching of the Si wafer, porous silicon (PS) layers with excellent broadband anti-reflection properties can be fabricated. In this work, ageing of graded PS has been studied using Spectroscopic Ellipsometry, Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. During oxidation of PS elements such as pure Si (Si$^0$), Si$_2$O (Si$^+$), SiO (Si$^{2+}$), Si$_2$O$_3$ (Si$^{3+}$), and SiO$_2$ (Si$^{4+}$) are present. In addition both hydrogen and carbon is introduced to the PS in the form of Si$_3$SiH and CO. The oxide grows almost linearly with time when exposed to oxygen, from an average thickness of 0 - 3.8 nm for the surface PS. The oxidation is then correlated to the optical stability of multi-layered PS ARCs. It is found that even after extensive oxidation, the changes in the optical properties of the PS structures are small.

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

    SciTech Connect

    Li, Shaoyuan [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Silicon Metallurgy and Silicon Material Engineering Research Center of Universities in Yunnan Province, Kunming 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Ma, Wenhui, E-mail: mwhsilicon@163.com [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Silicon Metallurgy and Silicon Material Engineering Research Center of Universities in Yunnan Province, Kunming 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Zhou, Yang, E-mail: zhouyangnano@163.com [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Silicon Metallurgy and Silicon Material Engineering Research Center of Universities in Yunnan Province, Kunming 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Chen, Xiuhua; Xiao, Yongyin [Faculty of Physical Science and Technology, Yunnan University, Kunming 650091 (China); Ma, Mingyu [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Silicon Metallurgy and Silicon Material Engineering Research Center of Universities in Yunnan Province, Kunming 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Wei, Feng [Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Yang, Xi [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Silicon Metallurgy and Silicon Material Engineering Research Center of Universities in Yunnan Province, Kunming 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

    2014-05-01

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

  20. Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Wan, Yimao; Bullock, James; Cuevas, Andres

    2015-05-01

    This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta2O5) underneath plasma enhanced chemical vapour deposited silicon nitride (SiNx). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta2O5 and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 ?.cm and n-type 1.0 ?.cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm2 and 68 fA/cm2 are measured on 150 ?/sq boron-diffused p+ and 120 ?/sq phosphorus-diffused n+ c-Si, respectively. Capacitance-voltage measurements reveal a negative fixed insulator charge density of -1.8 × 1012 cm-2 for the Ta2O5 film and -1.0 × 1012 cm-2 for the Ta2O5/SiNx stack. The Ta2O5/SiNx stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.

  1. Structural Evolution of Silicon Oxide Nanowires via Head-Growth Solid-Liquid-Solid Process

    NASA Astrophysics Data System (ADS)

    Hsu, Cheng-Hang; Chan, Shih-Yu; Chen, Chia-Fu

    2007-11-01

    In this paper, we propose a growth mechanism for silicon oxide nanowires (SiONWs) as a unique solid-liquid-solid process. SiONWs were synthesized in a furnace at 1000 °C and cooled at a high rate. Nickel and gold were introduced as catalysts to dissolve and precipitate the silicon oxide originally prepared by wet oxidation. The ratio of nickel to gold determined the precipitation rate and different “octopus-like” structures were formed. At a specific cooling rate, composition and amount of a catalyst, aligned silicon oxide nanowires with unattached ends were obtained.

  2. Kinetic study of H-terminated silicon nanowires oxidation in very first stages

    NASA Astrophysics Data System (ADS)

    Bashouti, Muhammad Y.; Sardashti, Kasra; Ristein, Jürgen; Christiansen, Silke

    2013-01-01

    Oxidation of silicon nanowires (Si NWs) is an undesirable phenomenon that has a detrimental effect on their electronic properties. To prevent oxidation of Si NWs, a deeper understanding of the oxidation reaction kinetics is necessary. In the current work, we study the oxidation kinetics of hydrogen-terminated Si NWs (H-Si NWs) as the starting surfaces for molecular functionalization of Si surfaces. H-Si NWs of 85-nm average diameter were annealed at various temperatures from 50°C to 400°C, in short-time spans ranging from 5 to 60 min. At high temperatures ( T ? 200°C), oxidation was found to be dominated by the oxide growth site formation (made up of silicon suboxides) and subsequent silicon oxide self-limitation. Si-Si backbond oxidation and Si-H surface bond propagation dominated the process at lower temperatures ( T < 200°C).

  3. Kinetic study of H-terminated silicon nanowires oxidation in very first stages

    PubMed Central

    2013-01-01

    Oxidation of silicon nanowires (Si NWs) is an undesirable phenomenon that has a detrimental effect on their electronic properties. To prevent oxidation of Si NWs, a deeper understanding of the oxidation reaction kinetics is necessary. In the current work, we study the oxidation kinetics of hydrogen-terminated Si NWs (H-Si NWs) as the starting surfaces for molecular functionalization of Si surfaces. H-Si NWs of 85-nm average diameter were annealed at various temperatures from 50°C to 400°C, in short-time spans ranging from 5 to 60 min. At high temperatures (T ? 200°C), oxidation was found to be dominated by the oxide growth site formation (made up of silicon suboxides) and subsequent silicon oxide self-limitation. Si-Si backbond oxidation and Si-H surface bond propagation dominated the process at lower temperatures (T < 200°C). PMID:23336401

  4. Dry oxidation of silicon: A new model of growth including relaxation of stress by viscous flow

    NASA Astrophysics Data System (ADS)

    Fargeix, A.; Ghibaudo, G.

    1983-12-01

    This paper deals with a model of silicon oxidation including stress relaxation by viscous flow during growth. Based on a Deal-Grove process and a Maxwellian stress relaxation approach, an integrodifferential equation giving the inverse growth rate dt/deox vs eox is established. Valid in any case of thickness growth rate dependence, it allows us to fit dry silicon oxidation data on a wide range of oxidation temperature (780-980 °C).

  5. Atomistic modeling of bending properties of oxidized silicon nanowires

    SciTech Connect

    Ilinov, Andrey, E-mail: andrey.ilinov@helsinki.fi; Kuronen, Antti [Department of Physics, University of Helsinki, P.O. Box 43, FIN-00014 Helsinki (Finland)

    2014-03-14

    In this work, we have modeled a three point bending test of monocrystalline Si nanowires using molecular dynamics simulations in order to investigate their elastic properties. Tested nanowires were about 30?nm in length and had diameters from 5 to 9?nm. To study the influence of a native oxide layer, nanowires were covered with a 1?nm thick silica layer. The bending force was applied by a carbon diamond half-sphere with a 5?nm diameter. The Si-O parametrization for the Tersoff potential was used to describe atomic interactions between Si and O atoms. In order to remove the indentation effect of the diamond half-sphere and to obtain a pure bending behavior, we have also performed a set of simulations with fixed bottoms of the nanowires. Our results show that the oxide layer reduces the nanowire stiffness when compared with a pure Si nanowire with the same number of silicon atoms—in spite of the fact that the oxidized nanowires had larger diameters.

  6. Atomistic modeling of bending properties of oxidized silicon nanowires

    NASA Astrophysics Data System (ADS)

    Ilinov, Andrey; Kuronen, Antti

    2014-03-01

    In this work, we have modeled a three point bending test of monocrystalline Si nanowires using molecular dynamics simulations in order to investigate their elastic properties. Tested nanowires were about 30 nm in length and had diameters from 5 to 9 nm. To study the influence of a native oxide layer, nanowires were covered with a 1 nm thick silica layer. The bending force was applied by a carbon diamond half-sphere with a 5 nm diameter. The Si-O parametrization for the Tersoff potential was used to describe atomic interactions between Si and O atoms. In order to remove the indentation effect of the diamond half-sphere and to obtain a pure bending behavior, we have also performed a set of simulations with fixed bottoms of the nanowires. Our results show that the oxide layer reduces the nanowire stiffness when compared with a pure Si nanowire with the same number of silicon atoms—in spite of the fact that the oxidized nanowires had larger diameters.

  7. The Interrelationship of Germanium Redistribution and Oxidation Kinetics during the Oxidation of Germanium - Silicon.

    NASA Astrophysics Data System (ADS)

    Frey, Eric Charles

    Single crystal silicon samples were doped with germanium using ion implantation, molecular beam epitaxy and chemical vapor deposition. The effect of oxidation conditions on Ge redistribution and the effect of Ge on oxidation kinetics were studied for steam oxidations at 800^circC to 1000 ^circC and for oxidations at 740 ^circC in 100-200 atm. of dry oxygen. Ge redistribution was measured with RBS and SIMS. It was found that, in agreement with other researchers, for atmospheric pressure oxidations the Ge rejected from the oxide and accumulated at the Si-SiO_2 interface forming a thin epitaxial Ge-rich layer. However for high pressure oxidations it was found that Ge was rejected from the oxide only until a critical quantity of Ge had accumulated at the interface and continued oxidation resulted in trapping of Ge in the oxide. A model was developed to explain the magnitude of the critical quantity of Ge for the onset of trapping. The model is based on a steady state equilibrium between the diffusive flux of Si through the Ge-rich layer and the rate at which Si is consumed by oxidation. Intimately related to the redistribution of the Ge is the change in oxidation kinetics. The effect of Ge on oxidation kinetics was determined by analyzing kinetics data using both a reaction rate analysis and an analysis of the data using the Linear-Parabolic model. The results indicate that Ge increases the rate of processes at the surface. However it was observed that GE reduces the parabolic rate and for oxidations in the parabolic regime (long time, high temperature) we have observed that samples containing Ge have thinner oxides than pure Si samples. Using the model developed to explain the critical quantity of Ge for the onset of trapping we have analyzed the effect of the quantity of Ge on the oxidation rate and found that the enhancement in oxidation rate is linearly related to the concentration of Ge at the interface.

  8. Finite Ground Coplanar Lines on CMOS Grade Silicon with a Thick Embedded Silicon Oxide Layer Using Micromachining Techniques

    Microsoft Academic Search

    Guoan Wang; Andrew Bacon; Reza Abdolvand; J. Papapolymerou; Emmanouil M. Tentzeris

    2003-01-01

    Finite Ground Coplanar (FGC) waveguide transmission lines on CMOS grade silicon wafer (¿<0.01 ohm-cm) with a thick embedded silicon oxide layer have been developed using micromachining techniques. Lines with different lengths were designed, fabricated and measured. Measured attenuation and s-parameters are presented in the paper. Results show that the attenuation loss of the fabricated FGC lines is as low as

  9. Development of thin film amorphous silicon oxide\\/microcrystalline silicon double-junction solar cells and their temperature dependence

    Microsoft Academic Search

    K. Sriprapha; C. Piromjit; A. Limmanee; J. Sritharathikhun

    2011-01-01

    We have developed thin film silicon double-junction solar cells by using micromorph structure. Wide bandgap hydrogenated amorphous silicon oxide (a-SiO:H) film was used as an absorber layer of top cell in order to obtain solar cells with high open circuit voltage (Voc), which are attractive for the use in high temperature environment. All p, i and n layers were deposited

  10. Growth of bismuth oxide films by direct liquid injection-metal organic chemical vapor deposition with Bi(tmhd) 3 (tmhd: 2,2,6,6-tetramethyl-3,5-heptanedione)

    Microsoft Academic Search

    S. W. Kang; S. W. Rhee

    2004-01-01

    Bismuth oxide films were deposited at 225–425 °C by direct liquid injection (DLI)-metal organic chemical vapor deposition (MOCVD) process with Bi(tmhd)3 (tmhd : 2,2,6,6-tetramethyl-3,5-heptanedione) dissolved in n-butylacetate. The deposition rate of Bi2O3 film was determined by surface reaction with the apparent activation energy of 15 kcal\\/mol. The growth rate was decrease above 325 °C because of the gas phase dissociation

  11. Investigation of the oxidative ammonolysis of propylene on oxide catalysts containing molybdenum and using the response method

    SciTech Connect

    Gadzhiev, K.N.; Adzhamov, K.Y.; Alkhazov, T.G.; Khanmamedova, A.K.

    1985-07-01

    The response method has been used to study the oxidative ammonolysis of propylene on MoO/sub 3/ and molybdenum oxide systems containing bismuth, silicon, and phosphorous ions. The response curves obtained for ammonia, propylene, CO/sub 2/, acrolein, acrylonitrile in these systems are discussed and compared with individual molybdenum trioxide. It has been shown that the modifying action of ammonia on the catalyst surfaces determines the direction of the oxidative conversion of the propylene.

  12. Novel synthetic methodology for controlling the orientation of zinc oxide nanowires grown on silicon oxide substrates.

    PubMed

    Cho, Jinhyun; Salleh, Najah; Blanco, Carlos; Yang, Sungwoo; Lee, Chul-Jin; Kim, Young-Woo; Kim, Jungsang; Liu, Jie

    2014-04-01

    This study presents a simple method to reproducibly obtain well-aligned vertical ZnO nanowire arrays on silicon oxide (SiOx) substrates using seed crystals made from a mixture of ammonium hydroxide (NH4OH) and zinc acetate (Zn(O2CCH3)2) solution. In comparison, high levels of OH(-) concentration obtained using NaOH or KOH solutions lead to incorporation of Na or K atoms into the seed crystals, destroying the c-axis alignment of the seeds and resulting in the growth of misaligned nanowires. The use of NH4OH eliminates the metallic impurities and ensures aligned nanowire growth in a wide range of OH(-) concentrations in the seed solution. The difference of crystalline orientations between NH4OH- and NaOH-based seeds is directly observed by lattice-resolved images and electron diffraction patterns using a transmission electron microscope (TEM). This study obviously suggests that metallic impurities incorporated into the ZnO nanocrystal seeds are one of the factors that generates the misaligned ZnO nanowires. This method also enables the use of silicon oxide substrates for the growth of vertically aligned nanowires, making ZnO nanostructures compatible with widely used silicon fabrication technology. PMID:24584438

  13. The composition of ultrathin silicon oxynitrides thermally grown in nitric oxide

    E-print Network

    Gustafsson, Torgny

    The composition of ultrathin silicon oxynitrides thermally grown in nitric oxide E. P. Gusev, H. C for publication 8 April 1997 The thermal oxynitridation of Si 100 in nitric oxide NO has been studied by high oxynitrides (SiOxNy) are the leading candidates to replace conventional oxides (SiO2) as the gate dielectric

  14. Epitaxial integration of perovskite-based multifunctional oxides on silicon q

    E-print Network

    Eom, Chang Beom

    Epitaxial integration of perovskite-based multifunctional oxides on silicon q Seung-Hyub Baek Epitaxial heterostructures of perovskite-type oxides have attracted much attention due to their enormous and multiferroics have been demonstrated in perovskite oxides. The combination of cations within perovskite unit

  15. Improved performance of microcrystalline silicon solar cell with graded-band-gap silicon oxide buffer layer

    NASA Astrophysics Data System (ADS)

    Shi, Zhen-Liang; Ji, Yun; Yu, Wei; Yang, Yan-Bin; Cong, Ri-Dong; Chen, Ying-Juan; Li, Xiao-Wei; Fu, Guang-Sheng

    2015-07-01

    Microcrystalline silicon (?c-Si:H) solar cell with graded band gap microcrystalline silicon oxide (?c-SiOx:H) buffer layer is prepared by plasma enhanced chemical vapor deposition and exhibits improved performance compared with the cell without it. The buffer layer moderates the band gap mismatch by reducing the barrier of the p/i interface, which promotes the nucleation of the i-layer and effectively eliminates the incubation layer, and then enhances the collection efficiency of the cell in the short wavelength region of the spectrum. The p/i interface defect density also decreases from 2.2 × 1012 cm?2 to 5.0 × 1011 cm?2. This graded buffer layer allows to simplify the deposition process for the ?c-Si:H solar cell application. Project supported by the Key Basic Research Project of Hebei Province, China (Grant Nos. 12963930D and 12963929D), the Natural Science Foundation of Hebei Province, China (Grant Nos. F2013201250 and E2012201059), and the Science and Technology Research Projects of the Education Department of Hebei Province, China (Grant No. ZH2012030).

  16. FT IR spectroscopy of nitric acid oxidation of silicon with hafnium oxide very thin layer

    NASA Astrophysics Data System (ADS)

    Kopani, M.; Mikula, M.; Pin?ík, E.; Kobayashi, H.; Takahashi, M.

    2014-05-01

    Hafnium oxide is promising for future CMOS devices owing to wide band gap, good thermal stability on silicon, high permittivity and high refractive index. Infrared spectroscopy was used to study of the structural properties of 5 nm HfO2 films after nitric acid oxidation (NAOS) of n-doped Si (1 0 0) substrates. Samples were annealed in N2 atmosphere at different temperatures 200-400 °C for 10 min. For NAOS passivation 100% vapor of HNO3 and 98% aqueous solution was used. The measurements revealed the formation of Hf-Si-O bonds depending on annealing temperature. The samples passivated in 98% aqueous HNO3 solution showed spectra with more developed Hf-Si-O structures. Obtained FTIR spectra indicate the presence of monoclinic HfO2 in amorphous layer in samples of A set and formation of cubic HfO2 phase in amorphous layer with increasing of temperature. Infrared spectroscopy reveals the stable solid silicon oxide layer. The structural properties of HfO2 are crucial for application in the future.

  17. Structural and chemical characteristics and oxidation behaviour of chromium-implanted single crystal silicon carbide

    Microsoft Academic Search

    H. Du. Z. Yang; M. Libera; D. C. Jacobson; Y. C. Wang; R. F. Davis

    1995-01-01

    High-dose chromium implantation resulted in complex changes in the structure, chemistry, and oxidation behaviour of beta-type\\u000a single-crystal silicon carbide. Detailed analytical studies indicated that, in addition to the primary process of surface\\u000a doping, chromium implantation of silicon carbide to 3.901017 ions cm?2 at 200 keV was accompanied by many secondary processes such as surface sputtering, lattice damaging, and silicon depletion\\/carbon

  18. Interaction between water and fluorine-doped silicon oxide film deposited by PECVD

    Microsoft Academic Search

    M. Yoshimaru; S. Koizumi; K. Shimokawa; J. Ida

    1997-01-01

    The interaction between water and fluorine-doped silicon oxide (SiOF) films has been studied focusing on the relation between the fluorine bonding configuration in the film and film hygroscopicity. SiOF films with a high fluorine concentration have three IR absorption bands between 985 cm-1 and 920 cm-1. These bands are assumed to be attributable to silicon monofluoride and silicon difluoride sites.

  19. Monolithic vertical integration of metal-oxide-semiconductor transistor with subterranean photonics in silicon

    Microsoft Academic Search

    Tejaswi Indukuri; Prakash Koonath; Bahram Jalali

    2006-01-01

    Monolithic integration of photonics and electronics has been achieved in silicon by vertically integrating metal-oxide-semiconductor field-effect transistors and waveguide-coupled microdisk resonators in a double-layer silicon-on-insulator wafer, thus paving the way towards dense three-dimensional optoelectronic integration

  20. Organically Capped Silicon Nanoparticles with Blue Photoluminescence Prepared by Hydrosilylation Followed by Oxidation

    E-print Network

    Swihart, Mark T.

    Followed by Oxidation Fengjun Hua, Folarin Erogbogbo, Mark T. Swihart, and Eli Ruckenstein* Department, including fracturing of porous silicon by ultrasonication,1,2 inverse micellar growth,3 laser ablation,4 the possibility of using silicon nanoparticles in potential applications such as full-color displ

  1. Relationship between storage media and blue photoluminescence for oxidized porous silicon

    Microsoft Academic Search

    A. Loni; A. J. Simons; P. D. J. Calcott; J. P. Newey; T. I. Cox; L. T. Canham

    1997-01-01

    Blue photoluminescence is observed, with nanosecond decay time, from rapid thermally oxidized porous silicon as a result of accelerated aging in plastic containers. Photoluminescence measurements, combined with chemical analyses of the “aged” porous silicon, indicate that the emission is a consequence of the incorporation of trace organic (hydrocarbon) contamination from the plastic containers as they outgas at a mildly elevated

  2. Method for forming indium oxide/n-silicon heterojunction solar cells

    DOEpatents

    Feng, Tom (Morris Plains, NJ); Ghosh, Amal K. (New Providence, NJ)

    1984-03-13

    A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

  3. Silicone\\/polypropylene oxide-polyethylene oxide copolymer\\/clay composites (i) - curing behavior, intermolecular interaction and thermomechanical properties

    Microsoft Academic Search

    Hsien-Tang Chiu; Jyh-Horng Wu

    2005-01-01

    This research explores the dispersion pattern, curing behavior and intermolecular interaction of liquid silicone, polypropylene oxide-polyethylene oxide copolymer and clay composites. It analyzes the curing behavior of each component composite by means of the rigid-body pendulum rheometer, and then it is followed by the exploration of the intermolecular interaction with the dynamic mechanical analysis. Results show that the polymer chains

  4. Bismuth-Oxide-Based Nonlinear Fiber With a High SBS Threshold and Its Application to Four-Wave-Mixing Wavelength Conversion Using a Pure Continuous-Wave Pump

    NASA Astrophysics Data System (ADS)

    Lee, Ju Han; Nagashima, Tatsuo; Hasegawa, Tomoharu; Ohara, Seiki; Sugimoto, Naoki; Kikuchi, Kazuro

    2006-01-01

    The unique and practical benefits of the use of bismuth-oxide-based nonlinear fiber (Bi-NLF) in implementing a four-wave-mixing (FWM)-based wavelength converter for fiber-optic-communication-system applications are experimentally demonstrated. First, the Kerr-nonlinearity and stimulated-Brillouin-scattering (SBS) characteristics of our fabricated Bi-NLF are experimentally investigated. The Bi-NLF is found to have the superior advantage of a significantly high SBS threshold in addition to its ultrahigh Kerr nonlinearity gamma of sim 1100 W-1 · km-1, compared to the conventional silica-based highly nonlinear fiber. Next, the authors perform an experiment for the FWM-based wavelength conversion of a non-return-to-zero (NRZ) signal within a 40-cm length of the Bi-NLF fusion spliced to standard silica fibers by using a continuous-wave (CW) high-power pump beam. Error-free tunable wavelength conversion over a 10-nm bandwidth is readily achieved. No SBS-suppression scheme is employed for the pump due to the high SBS threshold, which simplifies the system configuration and improves the quality of the wavelength-converted signal.

  5. Fracture Properties of LPCVD Silicon Nitride and Thermally Grown Silicon Oxide Thin Films From the Load-Deflection of Long and Diaphragms

    Microsoft Academic Search

    Jinling Yang; João Gaspar; Oliver Paul

    2008-01-01

    The bulge test is successfully extended to the determination of the fracture properties of silicon nitride and oxide thin films. This is achieved by using long diaphragms made of silicon nitride single layers and oxide\\/nitride bilayers, and applying a comprehensive mechanical model that describes the mechanical response of the diaphragms under uniform differential pressure. The model is valid for thin

  6. Nanostructurized Forms of Bismuth

    Microsoft Academic Search

    Oxana V. Kharissova; Boris I. Kharisov

    2008-01-01

    Recent advances on various nanoforms of bismuth (nanoparticles, nanowires, nanolines, nanobelts, etc.) are reviewed. Synthetic techniques, physical properties, and applications of these nanoforms are examined.

  7. The electroluminescence mechanism of Er³? in different silicon oxide and silicon nitride environments

    SciTech Connect

    Rebohle, L., E-mail: l.rebohle@hzdr.de; Wutzler, R.; Braun, M.; Helm, M.; Skorupa, W. [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Berencén, Y.; Ramírez, J. M.; Garrido, B. [Dept. Electrònica, Martí i Franquès 1, Universitat de Barcelona, 08028 Barcelona (Spain); Hiller, D. [IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)

    2014-09-28

    Rare earth doped metal-oxide-semiconductor (MOS) structures are of great interest for Si-based light emission. However, several physical limitations make it difficult to achieve the performance of light emitters based on compound semiconductors. To address this point, in this work the electroluminescence (EL) excitation and quenching mechanism of Er-implanted MOS structures with different designs of the dielectric stack are investigated. The devices usually consist of an injection layer made of SiO? and an Er-implanted layer made of SiO?, Si-rich SiO?, silicon nitride, or Si-rich silicon nitride. All structures implanted with Er show intense EL around 1540 nm with EL power efficiencies in the order of 2 × 10?³ (for SiO?:Er) or 2 × 10??(all other matrices) for lower current densities. The EL is excited by the impact of hot electrons with an excitation cross section in the range of 0.5–1.5 × 10?¹?cm?². Whereas the fraction of potentially excitable Er ions in SiO? can reach values up to 50%, five times lower values were observed for other matrices. The decrease of the EL decay time for devices with Si-rich SiO? or Si nitride compared to SiO? as host matrix implies an increase of the number of defects adding additional non-radiative de-excitation paths for Er³?. For all investigated devices, EL quenching cross sections in the 10?²? cm² range and charge-to-breakdown values in the range of 1–10 C cm?² were measured. For the present design with a SiO? acceleration layer, thickness reduction and the use of different host matrices did not improve the EL power efficiency or the operation lifetime, but strongly lowered the operation voltage needed to achieve intense EL.

  8. Memory characteristics of laser-crystallized polycrystalline-silicon silicon-oxide-nitride-oxide-silicon thin-film transistor with location-controlled grain boundary perpendicular to the channel

    NASA Astrophysics Data System (ADS)

    Lee, I.-Che; Tsai, Chun-Chien; Kuo, Hsu-Hang; Yang, Po-Yu; Wang, Chao-Lung; Cheng, Huang-Chung

    2012-06-01

    An excimer-laser-crystallized polycrystalline-silicon silicon-oxide-nitride-oxide-silicon thin-film transistor with recessed-channel structure has been designed to achieve only one grain boundary with a protrusion perpendicular to the channel for investigating the grain boundary location effects on the memory characteristics. After programming, the devices demonstrated better memory characteristics as the grain boundary was allocated near the source junction. In contrast, the memory characteristics were degraded when the grain boundary was located near the drain junction. The phenomenon was explained by the 2-D device simulation and the energy band diagrams.

  9. Fabrication of silicon-based multilevel nanostructures via scanning probe oxidation and anisotropic wet etching

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Y.; Zhang, J.; Luo, G.; Zhou, X.; Xie, G. Y.; Zhu, T.; Liu, Z. F.

    2005-04-01

    A rational approach is described for fabricating multilevel silicon-based nanostructures via scanning probe oxidation (SPO) and anisotropic wet etching. Using silicon oxide nanopatterns on Si(100) and Si(110) surfaces created by SPO as masks, two-dimensional (2D) nanostructures with high aspect ratio and a variety of patterns can be formed by anisotropic wet etching with KOH. By employing a mixture of KOH solutions and isopropyl alcohol (IPA) as an alternative to KOH alone, control of the morphology of the etched silicon surfaces, crucial for further fabrication, was greatly improved. The SPO and etching processes can be continually repeated on the 2D nanostructures, permitting the formation of various multilevel silicon-based nanostructures, including a T-gate structure useful for electronic circuitry. In addition, these multilevel silicon structures can be used as nanoimprint moulds for their rapid replication.

  10. Silicon oxide permeation barrier coating of PET bottles and foils

    NASA Astrophysics Data System (ADS)

    Steves, Simon; Deilmann, Michael; Awakowicz, Peter

    2009-10-01

    Modern packaging materials such as polyethylene terephthalate (PET) have displaced established materials in many areas of food and beverage packaging. Plastic packing materials offer are various advantages concerning production and handling. PET bottles for instance are non-breakable and lightweight compared to glass and metal containers. However, PET offers poor barrier properties against gas permeation. Therefore, the shelf live of packaged food is reduced. Permeation of gases can be reduced by depositing transparent plasma polymerized silicon oxide (SiOx) barrier coatings. A microwave (2.45 GHz) driven low pressure plasma reactor is developed based on a modified Plasmaline antenna to treat PET foils or bottles. To increase the barrier properties of the coatings furthermore a RF substrate bias (13.56 MHz) is applied. The composition of the coatings is analyzed by means of Fourier transform infrared (FTIR) spectroscopy regarding carbon and hydrogen content. Influence of gas phase composition and substrate bias on chemical composition of the coatings is discussed. A strong relation between barrier properties and film composition is found: good oxygen barriers are observed as carbon content is reduced and films become quartz-like. Regarding oxygen permeation a barrier improvement factor (BIF) of 70 is achieved.

  11. Influence of bismuth on cordierite polymorphism

    NASA Astrophysics Data System (ADS)

    Fiscina, J. E.; Malachevsky, M. T.; Soldera, F.; Vivas Hohl, J. A.; Esparza, D. A.

    2000-01-01

    Synthesis of Cordierite was carried out by solid state reaction sintering of oxides and Andean mineral precursors. Strong mechanic mixing was employed, with and without bismuth oxide added as a flux. Powder x-ray diffraction patterns were taken after sintering at different temperatures, in the range from 900 degree(s)C to 1400 degree(s)C. A comparative analysis was performed to investigate the phase formation dynamics for compositions with bismuth contents of 0, 5 and 13 %wt Bi2O3. Hexagonal (alpha) -Cordierite was obtained after sintering at 930 degree(s)C under the appropriate conditions. The behavior of the distortion index (Delta) with the sintering temperature reveals how the cordierite order-disorder polymorphism is affected by the bismuth addition. The resultant structure became more ordered with increasing sintering temperature. From the distortion index behavior and DTA measurements it can be observed that all the thermal events are shifted to lower temperatures for increasing bismuth contents. A preliminary study on sintering kinetics is presented from dilatometric measurements. The addition of bismuth would act as a catalyzer, through a liquid phase sintering process, by increasing the reaction rate and lowering the diffusion barriers.

  12. Electrical properties improvement of multicrystalline silicon solar cells using a combination of porous silicon and vanadium oxide treatment

    NASA Astrophysics Data System (ADS)

    Derbali, L.; Ezzaouia, H.

    2013-04-01

    In this paper, we will report the enhancement of the conversion efficiency of multicrystalline silicon solar cells after coating the front surface with a porous silicon layer treated with vanadium oxide. The incorporation of vanadium oxide into the porous silicon (PS) structure, followed by a thermal treatment under oxygen ambient, leads to an important decrease of the surface reflectivity, a significant enhancement of the effective minority carrier lifetime (?eff) and a significant enhancement of the photoluminescence (PL) of the PS structure. We Obtained a noticeable increase of (?eff) from 3.11 ?s to 134.74 ?s and the surface recombination velocity (Seff) have decreased from 8441 cm s-1 to 195 cm s-1. The reflectivity spectra of obtained films, performed in the 300-1200 nm wavelength range, show an important decrease of the average reflectivity from 40% to 5%. We notice a significant improvement of the internal quantum efficiency (IQE) in the used multicrystalline silicon substrates. Results are analyzed and compared to those carried out on a reference (untreated) sample. The electrical properties of the treated silicon solar cells were improved noticeably as regard to the reference (untreated) sample.

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

    DOEpatents

    Natesan, K.

    1994-12-27

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

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

    DOEpatents

    Natesan, Ken (Naperville, IL)

    1994-01-01

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

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

    DOEpatents

    Natesan, K.

    1992-01-01

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

  16. On the influence of tin and bismuth UPD on Pt(111) and Pt(332) on the oxidation of CO

    Microsoft Academic Search

    H. Massong; S. Tillmann; T. Langkau; E. A. Abd El Meguid; H. Baltruschat

    1998-01-01

    Deposition of Sn on a Pt(111) electrode gives rise to a sharp redox peak which is not due to the adsorption\\/desorption of Sn. The catalytic effect of this Sn-UPD on the oxidation of adsorbed CO is negligible. UPD of Sn on Pt(332) and Pt(755) on the other hand, has a remarkable catalytic effect; the onset of CO oxidation is shifted

  17. Corrosion of ODS steels in lead–bismuth eutectic

    Microsoft Academic Search

    P. Hosemann; H. T. Thau; A. L. Johnson; S. A. Maloy; N. Li

    2008-01-01

    Oxide dispersion strengthened (ODS) ferritic steels are advanced materials being developed for high temperature applications. Their properties (high temperature strength, creep resistance, corrosion\\/oxidation resistance) make them potentially usable for high temperature applications in liquid metal cooled systems like liquid lead–bismuth eutectic cooled reactors and spallation sources. Corrosion tests on five different ODS alloys were performed in flowing liquid lead–bismuth eutectic

  18. Oxide films for solar cells obtained by the extraction pyrolytic method

    Microsoft Academic Search

    T. N. Patrusheva; A. V. Kindal’; K. A. Kalenistov; G. N. Bondarenko; S. I. Tsyganov; A. I. Khol’kin

    2009-01-01

    Oxide materials such as titanium dioxide and complex oxides of zinc, titanium, bismuth, and silicon are photoactive materials,\\u000a and therefore, it is promising to use them for solar cells manufacturing. In order to start the commercial production of oxide\\u000a film electrodes, it is necessary to develop the technology permitting the covering of large areas. In the presented work,\\u000a it is

  19. PHYSICAL REVIEW B 88, 075307 (2013) Variable conductivity of nanocomposite nickel oxide/porous silicon

    E-print Network

    Weiss, Sharon

    2013-01-01

    PHYSICAL REVIEW B 88, 075307 (2013) Variable conductivity of nanocomposite nickel oxide-state variable conductivity of nickel oxide/porous silicon nanocomposite thin films indicative of memristance number(s): 73.63.Bd, 73.61.At, 81.07.Bc, 66.30.Dn I. INTRODUCTION Analog resistance-state components

  20. Scanning tunneling microscopy uncovers the mechanism of silicon oxidation in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Hines, Melissa; Faggin, Marc; Bao, Kun; Gupta, Ankush; Aldinger, Brandon

    2012-02-01

    Because of their immense technological importance, silicon oxidation reactions have been studied intensely for decades under a variety of conditions. However, the disordered nature of the reaction product, silicon oxide, makes these reactions notoriously difficult to understand. In this work, silicon oxidation is coupled with a subsequent etching reaction, allowing the oxidation reactions to literally write an atomic-scale record of their reactivity into the etched surface -- a record that can be decoded into site-specific reaction rates, and thus chemical understanding, with the aid of simulations and infrared spectroscopy. This record overturns the long-standing and much-applied mechanism for the (low-temperature) oxidation of the technologically important face of silicon, Si(100), and shows that the unusually high reactivity of a previously unrecognized surface species leads to a self-propagating etching reaction that produces near-atomically-flat surfaces terminated by a single monolayer of hydrogen atoms. This finding shows that, contrary to expectation, the low-temperature oxidation of Si(100) is a highly site-specific reaction and suggests strategies for the uniform functionalization of the technologically relevant face of silicon by low-temperature reactions.

  1. Comparative analysis of oxidation methods of reaction-sintered silicon carbide for optimization of oxidation-assisted polishing.

    PubMed

    Shen, Xinmin; Dai, Yifan; Deng, Hui; Guan, Chaoliang; Yamamura, Kazuya

    2013-11-01

    Combination of the oxidation of reaction-sintered silicon carbide (RS-SiC) and the polishing of the oxide is an effective way of machining RS-SiC. In this study, anodic oxidation, thermal oxidation, and plasma oxidation were respectively conducted to obtain oxides on RS-SiC surfaces. By performing scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDX) analysis and scanning white light interferometry (SWLI) measurement, the oxidation behavior of these oxidation methods was compared. Through ceria slurry polishing, the polishing properties of the oxides were evaluated. Analysis of the oxygen element on polished surfaces by SEM-EDX was conducted to evaluate the remaining oxide. By analyzing the three oxidation methods with corresponding polishing process on the basis of schematic diagrams, suitable application conditions for these methods were clarified. Anodic oxidation with simultaneous polishing is suitable for the rapid figuring of RS-SiC with a high material removal rate; polishing of a thermally oxidized surface is suitable for machining RS-SiC mirrors with complex shapes; combination of plasma oxidation and polishing is suitable for the fine finishing of RS-SiC with excellent surface roughness. These oxidation methods are expected to improve the machining of RS-SiC substrates and promote the application of RS-SiC products in the fields of optics, molds, and ceramics. PMID:24216836

  2. The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures.

    PubMed

    Gerlach, D; Wimmer, M; Wilks, R G; Félix, R; Kronast, F; Ruske, F; Bär, M

    2014-12-21

    The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization. PMID:25363298

  3. Effect of oxidations on phosphorus-diffused crystalline-silicon substrates

    SciTech Connect

    Gee, J.M. [Sandia National Labs., Albuquerque, NM (United States); King, R.R.; Reiss, J.H.; Mitchell, K.W. [Siemens Solar Industries, Camarillo, CA (United States)

    1996-09-01

    Phosphorus diffusions are used in the fabrication process for nearly all crystalline-silicon (c-Si) photovoltaic solar cells to form the emitter of the solar cell. These phosphorous diffusions are also well known to have beneficial gettering benefits, i.e., deleterious metallic impurities are gettered from the bulk of the c-Si substrate into the phosphorous doped layer. In this study, we examined the effect of oxidations performed after the phosphorus diffusion. We were particularly interested in using the oxidation to passivate the surface of the phosphorus diffusion. Post-diffusion oxidations or moderate temperature steps in oxidizing ambients are also commonly found in commercial fabrication sequences of c-Si solar cells. we found that the bulk lifetime was degraded in Czochralski (Cz) silicon due to the post-diffusion oxidation unless there was a gettering agent present during the oxidation. Possible explanations for these results are presented at the end of the paper.

  4. Crack healing behavior of hot pressed silicon nitride due to oxidation

    NASA Technical Reports Server (NTRS)

    Choi, S. R.; Tikare, V.

    1992-01-01

    It is shown that limited oxidation of an MgO-containing, hot-pressed silicon nitride ceramic at 800 deg C and above results in increased strength due to crack healing. Slight oxidation of the surface produces enstatite and cristobalite which fills in cracks. More extensive oxidation leads to strength degradation due to the formation of new flaws by the evolution of N2 gas at the surface. The apparent fracture toughness also increased at 800 deg C and above due to oxidation. Bonds formed between the two surfaces of the crack during oxidation leads to a reduction in stress intensity at the crack tip, suggesting that valid high-temperature toughness values cannot be obtained in an air environment. The increase in strength due to crack healing by oxidation can be achieved without compromising the fatigue properties of the silicon nitride ceramic.

  5. The Electrical Characteristics of MetalOxideSemiconductor Field Effect Transistors Fabricated on Cubic Silicon Carbide

    Microsoft Academic Search

    Takeshi Ohshima; Kin Kiong Lee; Yuuki Ishida; Kazutoshi Kojima; Yasunori Tanaka; Tetsuo Takahashi; Masahito Yoshikawa; Hajime Okumura; Kazuo Arai; Tomihiro Kamiya

    2003-01-01

    The n-channel metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated on cubic silicon carbide (3C-SiC) epitaxial layers grown on 3C-SiC substrates. The gate oxide of the MOSFETs was formed using pyrogenic oxidation at 1100 °C. The 3C-SiC MOSFETs showed enhancement type behaviors after annealing at 200 °C for 30 min in argon atmosphere. The maximum value of the effective channel mobility

  6. Evaluation of silicon oxide cleaning using F2\\/Ar remote plasma processing

    Microsoft Academic Search

    S. C. Kang; J. Y. Hwang; N.-E. Lee; K. S. Joo; G. H. Bae

    2005-01-01

    In this study, chamber cleaning experiments using a F2\\/Ar remote plasma generated from a toroidal-type remote plasma source were carried out in a plasma enhanced chemical vapor deposition (PECVD) system. The cleaning processes for the various silicon oxide layers, including PE-oxide (deposited by PECVD using SiH4 and N2O), O3-TEOS oxide (deposited by thermal CVD using ozone and TEOS precursor), and

  7. Surface modification of silicon oxide with trialkoxysilanes toward close-packed monolayer formation.

    PubMed

    Tanaka, Mutsuo; Sawaguchi, Takahiro; Kuwahara, Masashi; Niwa, Osamu

    2013-05-28

    In order to scrutinize potential of trialkoxysilanes to form close-packed monolayer, surface modification of silicon oxide was carried out with the trialkoxysilanes bearing a ferrocene moiety for analysis by electrochemical methods. As it was found that hydrogen-terminated silicon reacts with trialkoxysilane through natural oxidation in organic solvents, where the silicon oxide layer is thin enough to afford conductivity for electrochemical analysis, hydrogen-terminated silicon wafer was immersed in trialkoxysilane solution for surface modification without oxidation treatment. Cyclic voltammetry measurements to determine surface concentrations of the immobilized ferrocene-silane on silicon surface were carried out with various temperature, concentration, solvent, and molecular structure, while the blocking effect in the cyclic voltammogram was investigated to obtain insight into density leading to the close-packed layer. The results suggested that a monolayer modification tended to occur under milder conditions when the ferrocene-silane had a longer alkyl chain, and formation of a close-packed layer to show significant blocking effect was observed. However, the surface modification proceeded even when surface concentration of the immobilized ferrocene-silane was greater than that expected for the monolayer. On the basis of these tendencies, the surface of silicon oxide modified with trialkoxysilane is considered to be a partial multilayer rather than monolayer although a close-packed layer is formed. This result is supported by the comparison with carbon surface modified with ferrocene-diazonium, in which a significant blocking effect was observed when surface concentrations of the immobilized ferrocene moiety are lower than that for silicon oxide modified with ferrocene-silane. PMID:23668922

  8. Optimization of contaminated oxide inversion layer solar cell. [considering silicon oxide coating

    NASA Technical Reports Server (NTRS)

    Call, R. L.

    1976-01-01

    Contaminated oxide cells have been fabricated with efficiencies of 8.6% with values of I sub sc = 120 ma, V sub oc = .54 volts, and curve factor of .73. Attempts to optimize the fabrication step to yield a higher output have not been successful. The fundamental limitation is the inadequate antireflection coating afforded by the silicon dioxide coating used to hold the contaminating ions. Coatings of SiO, therefore, were used to obtain a good antireflection coating, but the thinness of the coatings prevented a large concentration of the contaminating ions, and the cells was weak. Data of the best cell were .52 volts V sub oc, 110 ma I sub sc, .66 CFF and 6.7% efficiency.

  9. The apatite structure without an inversion center in a new bismuth calcium vanadium oxide: BiCa[sub 4]V[sub 3]O[sub 13

    SciTech Connect

    Huang, Jinfan; Sleight, A.W. (Oregon State Univ., Corvallis (United States))

    1993-05-01

    A new bismuth calcium vanadium oxide, BiCa[sub 4]V[sub 3]O[sub 13], with hexagonal symmetry has been synthesized: space group P6[sub 3] (No. 173), a = 9.819(2) [Angstrom], c = 7.033(2) [Angstrom], V = 587.2(3) [Angstrom][sup 3], and Z = 2. The structure was solved and refined from single crystal X-ray data leading to R = 0.055 and R[sub w] = 0.069 for 1076 unique reflections. Three different types of Ca sites were found: Ca(1) and Ca(2) coordinate to six O atoms, and Ca(3) coordinates to nine O atoms. There is no Bi site; instead, Bi partially occupies the Ca(1) and Ca(2) sites. The V atom is coordinated to four O atoms and forms a distorted tetrahedron with the V-O bond lengths ranging from 1.693(6) [Angstrom] to 1.72(1) [Angstrom] and O-V-O angles varying from 102.5(7)[degrees] to 114.7(6)[degrees]. The coordination polyhedra of Ca(1) and Ca(3) share faces forming chains along the c axis, and the coordination hexahedra of Ca(2) also form a chain along the c axis through sharing the corners among themselves. The VO[sub 4] tetrahedra connect the two types of chains forming a three dimensional structure. The BiCa[sub 4]V[sub 3]O[sub 13] formula may be written as A[sub 5](VO[sub 4])[sub 3]O to emphasize that this structure is essentially the same as the apatite structure, except that the inversion center is missing. Many compounds previously reported to have the apatite structure may actually have the lower symmetry version of this structure found in this study and thus be candidates for ferroelectricity. 15 refs., 4 figs., 4 tabs.

  10. Synthesis of metal silicide at metal/silicon oxide interface by electronic excitation

    NASA Astrophysics Data System (ADS)

    Lee, J.-G.; Nagase, T.; Yasuda, H.; Mori, H.

    2015-05-01

    The synthesis of metal silicide at the metal/silicon oxide interface by electronic excitation was investigated using transmission electron microscopy. A platinum silicide, ?-Pt2Si, was successfully formed at the platinum/silicon oxide interface under 25-200 keV electron irradiation. This is of interest since any platinum silicide was not formed at the platinum/silicon oxide interface by simple thermal annealing under no-electron-irradiation conditions. From the electron energy dependence of the cross section for the initiation of the silicide formation, it is clarified that the silicide formation under electron irradiation was not due to a knock-on atom-displacement process, but a process induced by electronic excitation. It is suggested that a mechanism related to the Knotek and Feibelman mechanism may play an important role in silicide formation within the solid. Similar silicide formation was also observed at the palladium/silicon oxide and nickel/silicon oxide interfaces, indicating a wide generality of the silicide formation by electronic excitation.

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  12. Preparation of highly aligned silicon oxide nanowires with stable intensive photoluminescence

    NASA Astrophysics Data System (ADS)

    Duraia, El-Shazly M.; Mansurov, Z. A.; Tokmolden, S.; Beall, Gary W.

    2010-02-01

    In this work we report the successful formation of highly aligned vertical silicon oxide nanowires. The source of silicon was from the substrate itself without any additional source of silicon. X-ray measurement demonstrated that our nanowires are amorphous. Photoluminescence measurements were conducted through 18 months and indicated that there is a very good intensive emission peaks near the violet regions. The FTIR measurements indicated the existence of peaks at 463, 604, 795 and a wide peak at 1111 cm -1 and this can be attributed to Si-O-Si and Si-O stretching vibrations. We also report the formation of the octopus-like silicon oxide nanowires and the growth mechanism of these structures was discussed.

  13. Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes

    PubMed Central

    von Borczyskowski, Christian; Graaf, Harald

    2013-01-01

    Summary This study investigates the controlled chemical functionalization of silicon oxide nanostructures prepared by AFM-anodization lithography of alkyl-terminated silicon. Different conditions for the growth of covalently bound mono-, multi- or submonolayers of distinctively functional silane molecules on nanostructures have been identified by AFM-height investigations. Routes for the preparation of methyl- or amino-terminated structures or silicon surfaces are presented and discussed. The formation of silane monolayers on nanoscopic silicon oxide nanostructures was found to be much more sensitive towards ambient humidity than, e.g., the silanization of larger OH-terminated silica surfaces. Amino-functionalized nanostructures have been successfully modified by the covalent binding of functional fluorescein dye molecules. Upon excitation, the dye-functionalized structures show only weak fluorescence, which may be an indication of a relatively low surface coverage of the dye molecules on length scale that is not accessible by standard AFM measurements. PMID:23616941

  14. Structural, Compositional and Electrical Characterization of buried silicon oxide insulating layers synthesized by SIMOX process

    NASA Astrophysics Data System (ADS)

    Patel, A. P.; Yadav, A. D.; Dubey, S. K.; Panigrahi, B. K.; Nair, K. G. M.; Kumar, P.

    2010-06-01

    Silicon oxide (SiO2) buried insulating layers were synthesized by SIMOX (separation by implanted oxygen) process using 140 keV 16O+ ion implantation at fluence levels ranging from 1.0×1017 to 1.0×1018 cm-2 into <111> single crystal silicon substrates at room temperature and at elevated temperature (325 °C). The post-implantation annealing was performed in order to recover the implantation-induced structural damage. The structural, compositional and electrical characterization of the ion-beam synthesized buried silicon oxide insulating layers were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS) measurements and Current-voltage (I-V) characteristics. The FTIR spectra of implanted samples reveal absorption band in the wavenumber range 1200-800 cm-1 associated with the stretching vibration of Si-O bonds indicating the formation of silicon oxide. The FTIR spectra of annealed samples revealed absorption band associated with one bending vibration in addition to the asymmetric stretching vibration of Si-O bonds. The FTIR studies show that the structures of ion-beam synthesized buried oxide layers are strongly dependent on total ion fluence. The XRD data show the formation of silicon oxide (SiO2) structure at all ion fluences. The concentration of the formed phases is found to increase with increase in the ion fluence as well as the annealing temperature. The RBS measurements show that the thickness of the buried oxide layer increases with increase in the oxygen fluence. However, the thickness of the top silicon layer was found to decrease with increase in the ion fluence. The I-V characteristics show that the currents flowing in buried oxide layers are ohmic in the low voltage region and space charge limited in the higher voltage range.

  15. Novel silicon metal-oxide semiconductor devices for molecular sensing and hot electron spectroscopy

    Microsoft Academic Search

    Jinman Yang

    2002-01-01

    This dissertation describes results from a novel hybrid molecular\\/metal-oxide-semiconductor field effect transistor (MOSFET). The device consists of a buried channel silicon-on-insulator MOSFET with a molecular monolayer attached to its surface. The device is made using a 2 mum minimum gate length, silicon MOSFET process developed in Arizona State University. A hybrid molecular\\/MOSFET structure that is sensitive to the presence of

  16. Effects of Ultraviolet Irradiation on the Properties of Evaporated Silicon Oxide Films

    Microsoft Academic Search

    R. A. Mickelsen

    1968-01-01

    The optical and dielectric properties of silicon oxide films formed by reactive evaporation of silicon monoxide are investigated. The films are prepared at a deposition rate of 4 Å?sec in 1×10?4 Torr oxygen. The optical absorption of the films is found to increase with increasing substrate and source temperatures; these variations are consistent with previously reported chemisorbed oxygen and gas-phase

  17. Silicon solar cells with monolithic rare-earth oxide upconversion layer

    Microsoft Academic Search

    Richard H. Sewell; Andrew Clark; Robin Smith; Scott Semans; Aleta Jamora; Gary Vosters

    2009-01-01

    A ternary rare-earth oxide (REO) up-conversion layer was deposited on monocrystalline thin film solar cells to demonstrate up-conversion of sub-band-gap solar radiation into the spectral range of silicon. Laser radiation from 1520 nm to 1560 nm was shown to generate an additional photocurrent in the underlying silicon solar cell. Through combinations of rare-earth ions, portions of the sub-band-gap solar spectrum

  18. Antimony promoted bismuth cerium molybdate catalysts

    SciTech Connect

    Brazdil, J.F.; Glaeser, L.C.; Grasselli, R.K.

    1990-05-01

    This patent describes an improvement in antimony-promoted bismuth cerium molybdate whereby the tendency of the catalyst to lose efectiveness over time is significantly reduced. This patent describes new catalysts which are also useful in other oxidation-type reactions such as the oxidation of acrolein and methacrolein to produce the corresponding unsaturated aldehydes and acids and the oxydehydrogenation of various olefins such as isoamylenes to produce the corresponding diolefins such as isoprene.

  19. Study of electrical properties of oxidized porous silicon for back surface passivation of silicon solar cells

    Microsoft Academic Search

    Suresh Kumar Dhungel; Jinsu Yoo; Kyunghae Kim; Somnath Ghosh; Sungwook Jung; Junsin Yi

    2008-01-01

    Back surface passivation becomes a key issue for the silicon solar cells made with thin wafers. The high surface recombination due to the metal contacts can be lowered by reducing the back contact area and forming local back surface field (LBSF) in conjunction with the passivation with dielectric layer. About 3×10-7m thick porous silicon (PS) layer with pore diameter mostly

  20. High-Quality Solution-Processed Silicon Oxide Gate Dielectric Applied on Indium Oxide Based Thin-Film Transistors.

    PubMed

    Jaehnike, Felix; Pham, Duy Vu; Anselmann, Ralf; Bock, Claudia; Kunze, Ulrich

    2015-07-01

    A silicon oxide gate dielectric was synthesized by a facile sol-gel reaction and applied to solution-processed indium oxide based thin-film transistors (TFTs). The SiOx sol-gel was spin-coated on highly doped silicon substrates and converted to a dense dielectric film with a smooth surface at a maximum processing temperature of T = 350 °C. The synthesis was systematically improved, so that the solution-processed silicon oxide finally achieved comparable break downfield strength (7 MV/cm) and leakage current densities (<10 nA/cm(2) at 1 MV/cm) to thermally grown silicon dioxide (SiO2). The good quality of the dielectric layer was successfully proven in bottom-gate, bottom-contact metal oxide TFTs and compared to reference TFTs with thermally grown SiO2. Both transistor types have field-effect mobility values as high as 28 cm(2)/(Vs) with an on/off current ratio of 10(8), subthreshold swings of 0.30 and 0.37 V/dec, respectively, and a threshold voltage close to zero. The good device performance could be attributed to the smooth dielectric/semiconductor interface and low interface trap density. Thus, the sol-gel-derived SiO2 is a promising candidate for a high-quality dielectric layer on many substrates and high-performance large-area applications. PMID:26039187

  1. Homoleptic tin and silicon amido compounds as precursors for low-temperature atmospheric pressure chemical vapor deposition of tin and silicon oxide thin films

    Microsoft Academic Search

    Lauren M. Atagi; David M. Hoffman; Jia-Rui Liu; Zongshuang Zheng; Wei-Kan Chu; Rodrigo R. Rubiano; Robert W. Springer; David C. Smith

    1994-01-01

    Tin oxide films doped with fluorine or antimony are transparent conductors used in optoelectronic devices and solar cells. Silicon oxide thin films are used as diffusion barriers, passivation layers and dielectric layers in the microelectronics industry. Tin oxide thin films are commonly deposited in atmospheric pressure chemical vapor deposition (APCVD) processes by hydrolyzing SnCl[sub 4] or by reacting tetramethyltin with

  2. Titanium-silicon oxide film structures for polarization-modulated infrared reflection absorption spectroscopy

    PubMed Central

    Dunlop, Iain E.; Zorn, Stefan; Richter, Gunther; Srot, Vesna; Kelsch, Marion; van Aken, Peter A.; Skoda, Maximilian; Gerlach, Alexander; Spatz, Joachim P.; Schreiber, Frank

    2010-01-01

    We present a titanium-silicon oxide film structure that permits polarization modulated infrared reflection absorption spectroscopy on silicon oxide surfaces. The structure consists of a ~6 nm sputtered silicon oxide film on a ~200 nm sputtered titanium film. Characterization using conventional and scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy and X-ray reflectometry is presented. We demonstrate the use of this structure to investigate a selectively protein-resistant self-assembled monolayer (SAM) consisting of silane-anchored, biotin-terminated poly(ethylene glycol) (PEG). PEG-associated IR bands were observed. Measurements of protein-characteristic band intensities showed that this SAM adsorbed streptavidin whereas it repelled bovine serum albumin, as had been expected from its structure. PMID:20418963

  3. Defects at electrode-oxide and electrode-silicon interfaces in VHSI device structures

    NASA Astrophysics Data System (ADS)

    Helms, C. R.; Taubenblatt, M. A.; Lew, P. W.; Plummer, J. D.

    1984-04-01

    The effect of impurities on the electrical properties of metal silicon interfaces has been investigated for Pt, Ta, Ti, Hf, and their silicides. These silicon-electrode systems are of critical importance in VHSIC and other VLSI systems. The impurities investigated include oxygen (as in SiO2 or metal oxides), carbon, and silicon dopants. In order to quantitatively determine the effect of these impurities on the electrical properties of the neutral silicon interface microanalysis measurements have been combined in situ with measurements of Schottky barrier height via internal photoemission. Using this combination of techniques, the interface chemical composition can be determined and related to the measured Schottky barrier height. With a few exceptions, we have found that reliable, reproducible, Schottky diodes on silicon can only be formed if the metal silicon structure is annealed above the silicide formation temperature, so that the silicide formation reaction can clean up the interface. In addition, we have determined the mechanism for the poor reproducibility in barrier height for a number of refractory metal silicon contacts which is related to thin oxides that may be present at the interface.

  4. The effect of zirconium oxide and quartz pigments on the heat and corrosion resistance properties of the silicone based coatings

    Microsoft Academic Search

    L. Mathivanan; A. K. Arof

    2000-01-01

    Silicone resin based protective coatings are generally used for high temperature applications. In this work, anti-corrosive and heat resistant properties of titanium dioxide, mica, zirconium oxide and quartz combination pigments with silicone resin as carrier vehicle in primer and top coat for mild steel surface have been evaluated. Promising results were obtained, showing that the ceramic pigments (zirconium oxide and

  5. Bismuth as a modifier of Au Pd catalyst: Enhancing selectivity in alcohol oxidation by suppressing parallel reaction

    SciTech Connect

    Villa, Alberto [Universita di Milano, Italy; Wang, Di [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Veith, Gabriel M [ORNL; Prati, Laura [Universita di Milano, Italy

    2012-01-01

    Bi has been widely employed as a modifier for Pd and Pt based catalyst mainly in order to improve selectivity. We found that when Bi was added to the bimetallic system AuPd, the effect on activity in alcohol oxidation mainly depends on the amount of Bi regardless its position, being negligible when Bi was 0.1 wt% and detectably negative when the amount was increased to 3 wt%. However, the selectivity of the reactions notably varied only when Bi was deposited on the surface of metal nanoparticles suppressing parallel reaction in both benzyl alcohol and glycerol oxidation. After a careful characterization of all the catalysts and additional catalytic tests, we concluded that the Bi influence on the activity of the catalysts could be ascribed to electronic effect whereas the one on selectivity mainly to a geometric modification. Moreover, the Bi-modified AuPd/AC catalyst showed possible application in the production of tartronic acid, a useful intermediate, from glycerol.

  6. Phase relations of bismuth-barium-strontium oxides and copper L x-ray spectroscopy of cuprates including YBCO

    NASA Astrophysics Data System (ADS)

    Muller, Karoline

    Three studies are presented. In the first, phase relations are determined for the Bi-Ba oxide pseudobinary (<50% BaO) in oxygen at 640-1000 °C. Essentially no BaO dissolves in alpha-Bi2O3. The other phases are solid solutions. The delta-Bi2O3 polymorph, stable at 730-825 °C, belongs to a face-centered cubic phase (FCC SS). BaO-saturated FCCSS and BiO1.5-saturated rhombohedral phase (beta) melt eutectically at 753 °C. BaO-saturated beta coexists with Bi3BaO5.5. The eutectic between beta and Bi3BaO5.5, is at 775+/-6 °C. At T<815 °C, Bi3BaO5.5 coexists with BiBaO3. A tetragonal phase (T4) forms by reaction of Bi3BaO 5.5 and BiBaO3. Bi3BaO5.5 melts incongruently at 820 °C to liquid and T4. T4 melts incongruently to liquid and BiBaO3. delta-Bi2O3 and beta, both anion conductors, have structures based on that of fluorite. Other oxides have perovskite-like structures. Bi in BiBaO3 is half pentavalent and half trivalent; other oxides have all Bi3+. Phase relations of the Bi-Ba-Sr oxide ternary were investigated at 725 °C (alkaline earth oxide <50%). The oxygen ion conducting beta phase and BaBiO3 do not coexist in a binary system. (Ba,Sr)O-containing beta is in equilibrium with the electronic conductor BaBiO3. Cu L-spectra of superconductors and related materials were determined to investigate the atomic environment of Cu. Spectra may be micron-scale probes of copper valence because Lalpha- and Lbeta x-rays result from 3d valence band?2p transitions. Energies of Cu Lalpha and Lbeta x-rays are ?940 eV and reproducible to 0.15 eV. Pure emission L spectra of Cu phases are similar; measured differences largely result from absorption. Cu self-absorption spectra are ratios of L emission spectra obtained with different accelerating potentials of primary electrons. CuO and Cu2O have identical Lalpha and Lbeta energies but differ in Lbeta-Lalpha intensity ratio. Greater self-absorption of Lbeta x-rays than Lalpha in Cu2O compared with CuO is due to shifts in L absorption edge energies. Different YBCO samples differ slightly in Lbeta-Lalpha ratio according to oxygen content; again a result of changes in self-absorption. Different Cu2+-bearing phases have slight differences in absorption edge positions so Lbeta-Lalpha ratio depends on bulk composition as well as copper valence.

  7. The improvement in oxidation resistance of CVD-SiC coated C\\/C composites by silicon infiltration pretreatment

    Microsoft Academic Search

    Yao-Can Zhu; S. Ohtani; Y. Sato; N. Iwamoto

    1998-01-01

    Silicon infiltration pretreatment has been used to improve the high-temperature oxidation resistance of CVD-SiC coated C\\/C composites. C\\/C composites were infiltrated with silicon in an Ar atmosphere and then coated with CVD-SiC coating to a thickness of ca 50 ?m. Isothermal and cyclic oxidation tests at 1500 on the CVD-SiC coated C\\/C composites with and without silicon infiltration pretreatment were

  8. Facile preparation of highly-dispersed cobalt-silicon mixed oxide nanosphere and its catalytic application in cyclohexane selective oxidation

    PubMed Central

    2011-01-01

    Highly dispersed cobalt-silicon mixed oxide [Co-SiO2] nanosphere was successfully prepared with a modified reverse-phase microemulsion method. This material was characterized in detail by X-ray diffraction, transmission electron microscopy, Fourier transform infrared, ultraviolet-visible diffuse reflectance spectra, X-ray absorption spectroscopy near-edge structure, and N2 adsorption-desorption measurements. High valence state cobalt could be easily obtained without calcination, which is fascinating for the catalytic application for its strong oxidation ability. In the selective oxidation of cyclohexane, Co-SiO2 acted as an efficient catalyst, and good activity could be obtained under mild conditions. PMID:22067075

  9. Plasma-Sprayed Refractory Oxide Coatings on Silicon-Base Ceramics

    NASA Technical Reports Server (NTRS)

    Tewari, Surendra

    1997-01-01

    Silicon-base ceramics are promising candidate materials for high temperature structural applications such as heat exchangers, gas turbines and advanced internal combustion engines. Composites based on these materials are leading candidates for combustor materials for HSCT gas turbine engines. These materials possess a combination of excellent physical and mechanical properties at high temperatures, for example, high strength, high toughness, high thermal shock resistance, high thermal conductivity, light weight and excellent oxidation resistance. However, environmental durability can be significantly reduced in certain conditions such as when molten salts, H2 or water vapor are present. The oxidation resistance of silicon-base materials is provided by SiO2 protective layer. Molten salt reacts with SiO2 and forms a mixture of SiO2 and liquid silicate at temperatures above 800C. Oxygen diffuses more easily through the chemically altered layer, resulting in a catastrophic degradation of the substrate. SiC and Si3N4 are not stable in pure H2 and decompose to silicon and gaseous species such as CH4, SiH, SiH4, N2, and NH3. Water vapor is known to slightly increase the oxidation rate of SiC and Si3N4. Refractory oxides such as alumina, yttria-stabilized zirconia, yttria and mullite (3Al2O3.2SiO2) possess excellent environmental durability in harsh conditions mentioned above. Therefore, refractory oxide coatings on silicon-base ceramics can substantially improve the environmental durability of these materials by acting as a chemical reaction barrier. These oxide coatings can also serve as a thermal barrier. The purpose of this research program has been to develop refractory oxide chemical/thermal barrier coatings on silicon-base ceramics to provide extended temperature range and lifetime to these materials in harsh environments.

  10. A simple way to prepare bismuth nanoparticles

    Microsoft Academic Search

    Yanbao Zhao; Zhijun Zhang; Hongxin Dang

    2004-01-01

    In this paper, we report a simple method to prepare bismuth nanoparticles from bulk bismuth. Bismuth nanoparticles of near spherical shape have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and other techniques. Bismuth nanoparticles have mean diameter of 40–50 nm and exhibit the same crystal structure as the bulk bismuth. The surface of bismuth nanoparticle has been

  11. Oxidation of Chemically-Vapor-Deposited Silicon Carbide in Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Nguyen, QuynhGiao N.

    1998-01-01

    Chemically-vapor-deposited silicon carbide (CVD SiC) was oxidized in carbon dioxide (CO2) at temperatures of 1200-1400 C for times between 96 and 500 h at several gas flow rates. Oxidation weight gains were monitored by thermogravimetric analysis (TGA) and were found to be very small and independent of temperature. Possible rate limiting kinetic mechanisms are discussed. Passive oxidation of SiC by CO2 is negligible compared to the rates measured for other oxidants that are also found in combustion environments, oxygen and water vapor.

  12. Analyses of silicon dioxide, magnesium oxide, lead fluoride, bismuth as low-pass velocity filters for neutrons

    NASA Technical Reports Server (NTRS)

    Connor, D.; Holmryd, S.

    1969-01-01

    Transmission measurement of neutrons by filter materials for low energy neutrons is important for the study of structure and dynamics of condensed matter. Since only thermal neutrons are useful for such experiments, filter materials that transmit thermal neutrons while attenuating fast neutrons and gamma rays are of considerable interest.

  13. The low temperature dielectric anomaly of bismuth-based ceramics

    Microsoft Academic Search

    Xiukai Cai; Chunlei Wang; Peilin Zhang; Weilie Zhong; Liangying Zhang; Xi Yao

    2001-01-01

    A series of bismuth-contained ceramics have been prepared and the dielectric properties of typical samples are investigated in the temperature range of 300 to 10K. There exists a dielectric anomaly occurred common to all the bismuth, zinc(nickel), niobium(tantalum) oxide pyrochlores. The possible polarization mechanism is suggested and discussed by carrying out the phenomenological model analysis. The tendency of the dielectric

  14. Investigation of Low Temperature, Atomic-Layer-Deposited Oxides on 4Hydrigen-Silicon Carbide and their Effect on the Silicon Carbide/Silicon Dioxide Interface

    NASA Astrophysics Data System (ADS)

    Haney, Sarah Kay

    Silicon carbide has long been considered an excellent substrate for high power, high temperature applications. Fabrication of conventional MOSFETs on silicon carbide (SiC) relies on thermal oxidation of the SiC for formation of the silicon dioxide (SiO2) gate oxide. Historically, direct oxidation was viewed favorably due to ease of fabrication. However, the resulting MOS devices have exhibited significant interface trap densities, Dit , which reduce effective inversion layer mobility by capturing free carriers and enhancing scattering. While nitridation has been shown to reduce Dit, the inversion layer electron mobility of these devices is still limited by the presence of carbon near the interface. Studies have suggested a low mobility transition region between the SiC and SiO2, on the SiC side, attributed to increased carbon concentration resulting from the thermal oxidation of the SiC. In this work, we have investigated the low temperature, atomic layer deposition (ALD) of SiO2 onto SiC compared to thermal oxidation of SiC for the fabrication of MOS devices. Avoiding the carbon out diffusion and subsequent carbon build-up resulting from thermal oxidation is expected to result in a superior, higher mobility MOSFET. A three-step ALD process using 3-aminopropyltriethoxysiliane (3-APTES), ozone and water was evaluated on silicon and SiC substrates. Ellipsometry and XPS were used to characterize blanket films, and showed good results. Capacitors fabricated on SiC showed the need for optimized post deposition anneals. The effect of post oxidation anneals in nitrogen, forming gas and nitric oxide were examined. The standard nitric oxide (NO) anneal that is used to improve Dit after thermal oxidation was also shown to be the best anneal for the low temperature deposited ALD oxides. Materials characterization of the nitrided ALD and nitrided thermal oxide samples was completed using STEM/EELS techniques in addition to the ellipsometry and XPS. STEM/EELS analysis of the samples revealed no significant difference in transition regions on either side of the SiC/SiO2 interface regardless of oxidation technique or anneal temperature or ambient. All samples analyzed exhibited approximately 2-3nm of transition region on either side of the interface with no evidence of carbon or silicon rich regions. XPS was also used to determine a valence band offset of 2.43eV for the ALD oxide on 4H-SiC. Lateral MOSFETs were fabricated on 4H-SiC substrates with the following oxidation treatments: thermal oxidation at 1175°C, thermal oxidation at 1175°C followed by a nitric oxide (NO) anneal at 1175°C, and ALD of SiC at 150°C followed by an NO post oxidation anneal (POA) at 1175°C. ALD of the SiO2 was performed using 3-aminopropyltriethoxysiliane (3-APTES), ozone and water. Field effect mobility values were comparable for these samples, suggesting common thermal oxidation steps were still limiting the mobility. As such additional lateral MOSFETs were fabricated without the incoming sacrificial oxidation steps. This sacrificial-oxidation free experiment showed a 15% improvement in peak field effect mobility for the nitrided ALD oxide samples as compared to the nitrided thermal oxides. SIMS of the interfaces revealed nitrogen concentrations of ˜6E21 at/cc in the nitrided ALD sample compared to ˜4-6E20 in the nitrided thermal sample. This extremely high level of nitrogen incorporation, which is unparalleled in NO annealed thermal oxides, is accountable for the increase in field effect mobility. The low deposition temperature of the ALD oxide causes high levels of carbon incorporation and greater number of dangling bonds at the interface. Both the dangling bonds and excess carbon acts as binding sites for the nitrogen, increasing the nitrogen concentration and resulting in higher mobilities. Results presented support the use of SiO2 deposited using low temperature atomic layer deposition for improved gate oxides on 4H-SiC MOSFETs given the opportunity for increased nitrogen incorporation. The elevated levels of nitrogen measured in the NO annealed

  15. Organically capped silicon nanoparticles with blue photoluminescence prepared by hydrosilylation followed by oxidation.

    PubMed

    Hua, Fengjun; Erogbogbo, Folarin; Swihart, Mark T; Ruckenstein, Eli

    2006-04-25

    A facile method of preparing stable blue-emitting silicon nanoparticles that are dispersible in common organic solvents is presented. Oxidation of yellow-emitting silicon nanoparticles with an organic monolayer grafted to their surface, using either UV irradiation in solution or heating in air, converted them to blue-emitting particles. The evolution of the PL spectrum and infrared absorption spectrum of the particles was followed during the oxidation process. The PL spectrum showed a decrease in the PL emission peak near 600 nm and the appearance and increase in intensity of a PL emission peak near 460 nm rather than a smooth blue shift of the emission spectrum from yellow to blue. The organic monolayer grafted to the particle surface was not degraded by this oxidation process, as demonstrated by FTIR and NMR spectroscopy. Similar results were achieved for particles with styrene, 1-octene, 1-dodecene, and 1-octadecene grafted to their surface, demonstrating that it is the silicon nanocrystal, and not the organic component, that is essential to this process. The organic monolayer allows the nanoparticles to form stable, clear colloidal dispersions in organic solvents and provides for the possibility of further chemical functionalization of the particles. Combined with previous work on organically grafted silicon nanoparticles with green through near-infrared emission, this enables the efficient and scalable preparation of stable colloidal dispersions of organically grafted silicon nanoparticles with emission spanning the entire visible spectrum. PMID:16618188

  16. Effect of the silicon/oxide interface on interstitials: Di-interstitial recombination

    NASA Astrophysics Data System (ADS)

    Law, M. E.; Haddara, Y. M.; Jones, K. S.

    1998-10-01

    Interstitials can recombine at an oxide/silicon interface. Previous experimental work produces contradictory results. Transient enhanced diffusion experiments suggest a nearly infinite surface recombination rate, while oxidation enhanced diffusion suggests a much weaker recombination rate. A di-interstitial mechanism is investigated, and analytic solutions are developed. This is compared to the more commonly used interstitial mechanism. The di-interstitial mechanism can account for most of the discrepancy in the data.

  17. Brightly photoluminescent phosphor materials based on silicon quantum dots with oxide shell passivation.

    PubMed

    Tu, Chang-Ching; Zhang, Qifeng; Lin, Lih Y; Cao, Guozhong

    2012-01-01

    We demonstrate silicon-based phosphor materials which exhibit bright photoluminescence from near-infra-red to green. The colloidal composites which are composed of silicon quantum dots (SiQDs) attached on micro-size silicon particles are synthesized by electrochemical etching of silicon wafers and then dispersed in ethanol. Subsequently, isotropic etching by HF/HNO3 mixture controls the size so as the emission wavelength of SiQDs, and forms an oxide passivating shell. The phosphors can further react with alkoxysilanes to form a stable suspension in non-polar solvents for solution-processing. The resulting red-light-emitting SiQD-based phosphors in chloroform exhibit photoluminescence external quantum efficiency of 15.9%. Their thin films can be efficiently excited by InGaN light-emitting diodes and are stable in room condition. PMID:22379666

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

    NASA Astrophysics Data System (ADS)

    Chao, Tsu-An

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

  19. Characterization of charge-carrier dynamics in thin oxide layers on silicon by second harmonic generation

    E-print Network

    Pantelides, Sokrates T.

    Characterization of charge-carrier dynamics in thin oxide layers on silicon by second harmonic and nonlin- ear optics have opened up new venues for fundamental stud- ies of carrier injection dynamics electric field arising from charge separation depends strongly on the dynamics of the charge carriers

  20. Giant isotope effect in hot electron degradation of metal oxide silicon devices

    Microsoft Academic Search

    Karl Hess; Isik C. Kizilyalli; Joseph W. Lyding

    1998-01-01

    A giant isotope effect of hot electron degradation was found by annealing and passivating integrated circuits of recent complementary metal oxide silicon (CMOS) technology with deuterium instead of hydrogen. In this paper, we summarize our experience and present new results of secondary ion mass spectroscopy that correlate deuterium accumulation with reduced hot electron degradation. We also present a first account

  1. Influence of process conditions on the surface oxidation of silicon nitride green compacts

    Microsoft Academic Search

    S. M. CASTANHO; R MORENO; J. L. G FIERRO

    1997-01-01

    The surface chemistry of silicon nitride is strongly influenced by the processing environment. Mixing and forming steps can modify the oxidation state at the surface of the particle. The aim of the present investigation is to determine the possible changes and interactions on the surface of the particle induced during processing by different techniques of formation, such as isostatic pressing

  2. New fabrication method of silicon field emitter arrays using thermal oxidation

    E-print Network

    Lee, Jong Duk

    .6 The evaporated oxide, however, has a few problems in achieving the above objective. First height to gate hole diameter is desirable to reduce the voltage required for field emission, this lateral -oriented single crystal silicon wafer with a resistivity of 10 cm. n-well is formed to be used as a cathode

  3. Vertically Stacked Silicon Nanowire Transistors Fabricated by Inductive Plasma Etching and Stress-Limited Oxidation

    Microsoft Academic Search

    Ricky M. Y. Ng; Tao Wang; Feng Liu; Xuan Zuo; Jin He; Mansun Chan

    2009-01-01

    A simple top-down method for realizing an array of vertically stacked nanowires is presented. The process utilizes the nonuniformity in inductively coupled plasma (ICP) etching to form a scallop pattern at the sidewall of a tall silicon ridge that is further trimmed to form stacked nanowires by stress-limited oxidation. The process has been demonstrated to be controllable and repeatable, starting

  4. Effect of Surface Oxidation on Micromachinability of Monocrystalline Silicon

    Microsoft Academic Search

    T. Inamura; G. Y. Feng; N. Takezawa; N. Mohri

    2001-01-01

    Microcutting experiments are carried out under an atomic force microscope (AFM) using workpieces of silicon monocrystals that have been exposed to air for various lengths of time before cutting. The results are observed under the same AFM with decreased tip force. The results show that difficult-to-cut areas appear locally after 24 hours of exposure time and these areas extend with

  5. Low-damage direct patterning of silicon oxide mask by mechanical processing

    PubMed Central

    2014-01-01

    To realize the nanofabrication of silicon surfaces using atomic force microscopy (AFM), we investigated the etching of mechanically processed oxide masks using potassium hydroxide (KOH) solution. The dependence of the KOH solution etching rate on the load and scanning density of the mechanical pre-processing was evaluated. Particular load ranges were found to increase the etching rate, and the silicon etching rate also increased with removal of the natural oxide layer by diamond tip sliding. In contrast, the local oxide pattern formed (due to mechanochemical reaction of the silicon) by tip sliding at higher load was found to have higher etching resistance than that of unprocessed areas. The profile changes caused by the etching of the mechanically pre-processed areas with the KOH solution were also investigated. First, protuberances were processed by diamond tip sliding at lower and higher stresses than that of the shearing strength. Mechanical processing at low load and scanning density to remove the natural oxide layer was then performed. The KOH solution selectively etched the low load and scanning density processed area first and then etched the unprocessed silicon area. In contrast, the protuberances pre-processed at higher load were hardly etched. The etching resistance of plastic deformed layers was decreased, and their etching rate was increased because of surface damage induced by the pre-processing. These results show that etching depth can be controlled by controlling the etching time through natural oxide layer removal and mechanochemical oxide layer formation. These oxide layer removal and formation processes can be exploited to realize low-damage mask patterns. PMID:24948891

  6. Low-damage direct patterning of silicon oxide mask by mechanical processing.

    PubMed

    Miyake, Shojiro; Yamazaki, Shohei

    2014-01-01

    To realize the nanofabrication of silicon surfaces using atomic force microscopy (AFM), we investigated the etching of mechanically processed oxide masks using potassium hydroxide (KOH) solution. The dependence of the KOH solution etching rate on the load and scanning density of the mechanical pre-processing was evaluated. Particular load ranges were found to increase the etching rate, and the silicon etching rate also increased with removal of the natural oxide layer by diamond tip sliding. In contrast, the local oxide pattern formed (due to mechanochemical reaction of the silicon) by tip sliding at higher load was found to have higher etching resistance than that of unprocessed areas. The profile changes caused by the etching of the mechanically pre-processed areas with the KOH solution were also investigated. First, protuberances were processed by diamond tip sliding at lower and higher stresses than that of the shearing strength. Mechanical processing at low load and scanning density to remove the natural oxide layer was then performed. The KOH solution selectively etched the low load and scanning density processed area first and then etched the unprocessed silicon area. In contrast, the protuberances pre-processed at higher load were hardly etched. The etching resistance of plastic deformed layers was decreased, and their etching rate was increased because of surface damage induced by the pre-processing. These results show that etching depth can be controlled by controlling the etching time through natural oxide layer removal and mechanochemical oxide layer formation. These oxide layer removal and formation processes can be exploited to realize low-damage mask patterns. PMID:24948891

  7. Silicon thermal oxidation and its thermal desorption investigated by Si 2p core-level photoemission

    NASA Astrophysics Data System (ADS)

    Enta, Y.; Nakazawa, H.; Sato, S.; Kato, H.; Sakisaka, Y.

    2010-06-01

    Initial thermal oxidation of silicon and thermal desorption of silicon oxide have been investigated by Si 2p core-level photoemission with synchrotron radiation. The surface reaction processes are discussed from the difference in the chemically-shifted components, especially suboxides. On the thermal oxidation, time evolutions of suboxide intensities show a distinct temperature dependence, which is explained by two growth modes for the oxidation: first-order Langmuir-type adsorption mode and two-dimensional island growth mode at oxidation temperatures below and above 650 °C, respectively. On the thermal desorption, the spectrum for the thermal oxide followed by annealing at 1000 °C for 30 s in vacuum, whose thickness is nominally estimated at 3.7 Å, are compared with the 3.3 Å-thickness thermal oxide without the process of the annealing. The intensities of the suboxide components are considerably different between them, which can be explained by the formation and lateral growth of the voids in the annealed oxide layer.

  8. Microstructure, oxidation behavior and mechanical behavior of lens deposited niobium-titanium-silicon and niobium-titanium-silicon based alloys

    NASA Astrophysics Data System (ADS)

    Dehoff, Ryan Richard

    With current high temperature structural materials such as nickel based superalloys being pushed to the limits of suitable operating conditions, there comes a need for replacement materials with even higher temperature capabilities. Niobium silicon based systems have been shown to have superior density normalized strength at elevated temperatures when compared to currently used alloys. The drawbacks associated with the niobium silicon system are due to catastrophic oxidation behavior at elevated temperatures. Alloying addition have been shown to increase the oxidation resistance near suitable levels, but also decrease the high temperature strength and increases creep rates when compared to the binary alloy system. The microstructure of the material is similar to metal matrix composites in which high melting temperature silicides are dispersed in a niobium based matrix phase. The silicides produce high temperature strength while the niobium based matrix increases the room temperature properties such as fracture toughness. The bulk of the research has been conducted on directionally solidified material which has a coarse microstructure due to the slow cooling rates associated with the processing condition. The current research uses a powder metallurgy process termed Laser Engineered Net Shaping, or LENS, to produce material with a significantly refined microstructure due to fast cooling rates associated with the laser process. Several compositions of alloys were examined and the ideal processing parameters were determined for each alloy. The resulting microstructures show a refinement of the microstructure as expected with a fine scale distribution of Nb5Si3 and Nb3Si dispersed in a niobium based matrix phase. The high temperature oxidation behavior of the LENS deposited alloys was comparable to alloys produced using other techniques. A non protective oxide scale formed on samples exposed for only 0.5 hours but was not protective and showed large amounts of spallation at extended exposure times. The increase in grain boundaries and interfaces did not significantly increase the internal oxidation rate despite increased oxidation rates along these defects. The high temperature compression behavior was comparable to other alloys and processing techniques despite having a lower silicon content and therefore a smaller volume fraction of strengthening phase present. Dissolved oxygen levels in the LENS deposits appeared to be responsible for the increased strength at elevated temperatures. The oxygen levels in LENS processed alloys were higher than material produced by other processing techniques. The current work illustrates that the LENS processing techniques is a viable processing method for niobium silicide based materials and potentially increases the strength of the material.

  9. Oxidation Kinetics of Chemically Vapor-Deposited Silicon Carbide in Wet Oxygen

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.

    1994-01-01

    The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

  10. Starting Material Silicon substrate

    E-print Network

    Healy, Kevin Edward

    2005 #12;N-Well Photo and Nitride Etch Silicon substrate Pad oxide Silicon nitride Photo resist Attila Horvath 2005 #12;P-Well Photo and Nitride Etch Silicon substrate Pad oxide Silicon nitride Photo resist N and Etch Silicon substrate Oxide N-WellP-Well P P NP Poly-Silicon Photo resist Attila Horvath 2005 #12;NMOS

  11. Modelling of silicon oxynitridation by nitrous oxide using the reaction rate approach

    NASA Astrophysics Data System (ADS)

    Dominique Krzeminski, Christophe

    2013-12-01

    Large technological progress in oxynitridation processing leads to the introduction of silicon oxynitride as ultra-thin gate oxide. On the theoretical side, few studies have been dedicated to the process modelling of oxynitridation. Such an objective is a considerable challenge regarding the various atomistic mechanisms occurring during this fabrication step. In this article, some progress performed to adapt the reaction rate approach for the modelling of oxynitride growth by a nitrous ambient are reported. The Ellis and Buhrman's approach is used for the gas phase decomposition modelling. Taking into account the mass balance of the species at the interface between the oxynitride and silicon, a minimal kinetic model describing the oxide growth has been calibrated and implemented. The influence of nitrogen on the reaction rate has been introduced in an empirical way. The oxidation kinetics predicted with this minimal model compares well with several experiments.

  12. Engineering polarization rotation in ferroelectric bismuth titanate

    NASA Astrophysics Data System (ADS)

    Roy, Amritendu; Prasad, Rajendra; Auluck, Sushil; Garg, Ashish

    2013-05-01

    We report a combined experimental-theoretical study showing that collective application of rare earth doping on Bi-site of ferroelectric bismuth titanate (Bi4Ti3O12) and epitaxial strain leads to only a small increase in c-axis polarization, resolving conflicts of previous experimental data on c-axis oriented thin films. However, as shown by our first principles calculations, a modest c-axis polarization can be induced by simultaneous Bi(A) and Ti(B) site doping in bismuth titanate. This approach, correlating doping, epitaxial strain, and polarization in ferroic oxides, could be useful to tailor oxide compositions, assisting in the growth of epitaxial films along easy growth directions yielding reasonable polarization.

  13. Crack healing in silicon nitride due to oxidation

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Tikare, Veena; Pawlik, Ralph

    1991-01-01

    The crack healing behavior of a commercial, MgO-containing, hot pressed Si3N4 was studied as a function of temperature in oxidizing and inert annealing environments. Crack healing occurred at a temperature 800 C or higher due to oxidation regardless of crack size, which ranged from 100 microns (indentation crack) to 1.7 mm (SEPB precrack). The resulting strength and apparent fracture toughness increased at crack healing temperature by 100 percent and 300 percent, respectively. The oxide layer present in the crack plane was found to be highly fatigue resistant, indicating that the oxide is not solely silicate glass, but a mixture of glass, enstatite, and/or cristobalite that was insensitive to fatigue in a room temperature water environment.

  14. Full field chemical imaging of buried native sub-oxide layers on doped silicon patterns

    NASA Astrophysics Data System (ADS)

    de la Peña, F.; Barrett, N.; Zagonel, L. F.; Walls, M.; Renault, O.

    2010-09-01

    Fully energy-filtered X-ray photoelectron emission microscopy is used to analyze the spatial distribution of the silicon sub-oxide structure at the SiO 2/Si interface as a function of underlying doping pattern. Using a spectroscopic pixel-by-pixel curve fitting analysis, we obtain the sub-oxide binding energy and intensity distributions over the full field of view. Binding energy maps for each oxidation state are obtained with a spatial resolution of 120 nm. Within the framework of a five-layer model, the experimental data are used to obtain quantitative maps of the sub-oxide layer thickness and also their spatial distribution over the p-n junctions. Variations in the sub-oxide thicknesses are found to be linked to the level and type of doping. The procedure, which takes into account instrumental artefacts, enables the quantitative analysis of the full 3D dataset.

  15. Oxidation Behavior of Germanium- and/or Silicon-Bearing Near-? Titanium Alloys in Air

    NASA Astrophysics Data System (ADS)

    Kitashima, Tomonori; Yamabe-Mitarai, Yoko

    2015-06-01

    The effect of germanium (Ge) and/or silicon (Si) addition on the oxidation behavior of the near-? alloy Ti-5Al-2Sn-4Zr-2Mo was investigated in air at 973 K (700 °C). Ge addition decreased the oxidation resistance because of the formation of a Ge-rich layer in the substrate at the TiO2/substrate interface, enhancing Sn segregation at the interface. In addition, a small amount of Ge dissolved in the external Al2O3 layer. These results reduced the aluminum activity at the interface, suppressed the formation of Al2O3, and increased the diffusivity of oxygen in the oxide scales. The addition of 0.2 and 0.9 wt pct Si was beneficial for improving oxidation resistance. The effect of germanide and silicide precipitates in the matrix on the oxide growth process was also discussed.

  16. Thin film germanium on silicon created via ion implantation and oxide trapping

    NASA Astrophysics Data System (ADS)

    Anthony, R.; Knights, A. P.

    2015-06-01

    We present a novel process for integrating germanium with silicon-on-insulator (SOI) wafers. Germanium is implanted into SOI which is then oxidized, trapping the germanium between the two oxide layers (the grown oxide and the buried oxide). With careful control of the implantation and oxidation conditions this process creates a thin layer (current experiments indicate up to 20-30nm) of almost pure germanium. The layer can be used potentially for fabrication of integrated photo-detectors sensitive to infrared wavelengths, or may serve as a seed for further germanium growth. Results are presented from electron microscopy and Rutherford back-scattering analysis, as well as preliminary modelling using an analytical description of the process.

  17. Silicon nanocrystals in an oxide matrix for thin film solar cells with 492 mV open circuit voltage

    Microsoft Academic Search

    I. Perez-Wurfl; L. Ma; D. Lin; X. Hao; M. A. Green; G. Conibeer

    We have fabricated solar cells with layers of co-sputtered silicon and silicon dioxide. The diode structures were fabricated by sputtering alternating layers of SiO2 and silicon rich oxide onto quartz substrates with in-situ boron, for p-type, and phosphorus, for n-type, doping. After crystallization at 1100°C, isolated Si-nanocrystals are formed. The thin film layers containing these crystals act as n-type or

  18. Effects of Fine Metal Oxide Particle Dopant on the Acoustic Properties of Silicone Rubber Lens for Medical Array Probe

    Microsoft Academic Search

    Yasuharu Hosono; Yohachi Yamashita; Kazuhiro Itsumi

    2007-01-01

    The effects of fine metal oxide particles, particularly those of high-density elements (7.7 to 9.7 times 103 kg\\/m3), on the acoustic properties of silicone rubber have been investigated in order to develop an acoustic lens with a low acoustic attenuation. Silicone rubber doped with Yb2O3 powder having nanoparticle size of 16 nm showed a lower acoustic attenuation than silicone rubber

  19. Identification and Control of Gravity Related Defect Formation During Melt Growth of Bismuth-Silicate (Bi12SiO20)

    NASA Technical Reports Server (NTRS)

    Zheng, Y.; Witt, A. F.

    1999-01-01

    In the light of strong indications that a majority of critical defects formed in bismuth silicon oxide (BSO) during growth from the melt is related directly or indirectly to gravitational interference, it is suggested to use the reduced gravity environment of outer space for experimentation directed at the identification and control of these defects. The results of these experiments are expected to lead to advances in our understanding of crystal growth related defect formation in general and will establish a basis for effective defect engineering, the approach to efficient achievement of defect related, application specific properties in opto-electronic materials

  20. Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

    Microsoft Academic Search

    1991-01-01

    A process is disclosed for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900--1500 C and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure

  1. Selective doping of silicon nanowires by means of electron beam stimulated oxide etching.

    PubMed

    Pennelli, G; Totaro, M; Piotto, M

    2012-02-01

    Direct patterning of silicon dioxide by means of electron beam stimulated etching is shown, and a full characterization of exposure dose is presented. For its high dose, this technique is unsuitable for large areas but can be usefully employed like a precision scalpel for removing silicon dioxide by well-localized points. In this work, this technique is applied to the definition of windows through the oxide surrounding top down fabricated n-doped silicon nanowires. These windows will be employed for a selective doping of the nanowire by boron diffusion. In this way, pn junctions can be fabricated in well-localized points in the longitudinal direction of the nanowire, and an electrical contact to the different junctions can be provided. Electrical I-V characteristics of a nanowire with pn longitudinal junctions are reported and discussed. PMID:22263806

  2. The growth of microcrystalline silicon oxide thin films studied by in situ plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Kirner, S.; Gabriel, O.; Stannowski, B.; Rech, B.; Schlatmann, R.

    2013-02-01

    The crystallinity and refractive index of microcrystalline silicon oxide (?c-SiOx:H) n-layers and their dependence on the pressure and radio frequency power during the deposition process is correlated with plasma properties derived from in situ diagnostics. From process gas depletion measurements, the oxygen content of the layers was calculated. High crystallinities were observed for increased pressures and decreased powers, indicating clear differences to trends previously shown for microcrystalline silicon (?c-Si:H) material, which are explained by the varying oxygen incorporation. Amorphous/microcrystalline silicon (a-Si:H/?c-Si:H) tandem solar cells with ?c-SiOx:H intermediate reflector layers deposited at optimized pressures showed greatly improved series resistances.

  3. Relationship between storage media and blue photoluminescence for oxidized porous silicon

    NASA Astrophysics Data System (ADS)

    Loni, A.; Simons, A. J.; Calcott, P. D. J.; Newey, J. P.; Cox, T. I.; Canham, L. T.

    1997-07-01

    Blue photoluminescence is observed, with nanosecond decay time, from rapid thermally oxidized porous silicon as a result of accelerated aging in plastic containers. Photoluminescence measurements, combined with chemical analyses of the "aged" porous silicon, indicate that the emission is a consequence of the incorporation of trace organic (hydrocarbon) contamination from the plastic containers as they outgas at a mildly elevated temperature (80 °C) and, albeit at a reduced rate, at room temperature. Such carbonaceous contaminants can subsequently be removed by high-temperature annealing, a process which also quenches the blue photoluminescence. Consequently, it is important to take into consideration the storage medium used when making comparative luminescent and compositional studies of porous silicon and, perhaps, porous materials in general.

  4. Indentation and oxidation studies on silicon nitride joints

    SciTech Connect

    Gopal, M.; De Jonghe, L.C.; Thomas, G. [California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley National Lab., CA (United States)

    1996-05-01

    Si nitride ceramics have been joined with a Y oxide-SiO{sub 2} interlayer. A 1:2 molar ratio of Y{sub 2}O{sub 3} to SiO{sub 2} was chosen to obtain the desired Y{sub 2}Si{sub 2}O{sub 7} stoichiometry, which should give the interlayer better oxidation resistance compared to other interlayer materials. Mechanical characterization of the joints performed by indentation shows it to have good room temperature strength.

  5. Intergrowth in complex bismuth oxides, Bi 2CaNa n-2 Nb nO 3 n+3 ( n = 5 ˜ 8), revealed by 1-MV high-resolution electron microscopy

    NASA Astrophysics Data System (ADS)

    Horiuchi, Shigeo; Muramatsu, Kunitaka; Shimazu, Masaji

    1980-08-01

    A complex bismuth oxide crystal, prepared by heating powders with a nominal composition Bi 2CaNb 2O 9·4NaNbO 3, is composed of several phases, Bi 2CaNa n-2 Nb nO 3 n+3 , mainly with n = 5-8. One-megavolt high-resolution electron microscopy reveals that the structure of each phase is constructed by perovskite-like layers interleaved with Bi 2O 2 sheets. Any one of these phases grows only in limited regions, in which other phases with different values of n intergrow very finely. This causes a characteristic intensity profile on the diffraction pattern. Experimental evidence on the reaction of the crystal with water is presented.

  6. Valley polarization in bismuth

    NASA Astrophysics Data System (ADS)

    Fauque, Benoit

    2013-03-01

    The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

  7. Properties of indium-tin-oxide (ITO)\\/silicon heterojunction solar cells by thick-film techniques

    Microsoft Academic Search

    H. B. Saim; D. S. Campbell

    1987-01-01

    Indium-tin-oxide (ITO)\\/silicon SIS solar cells were prepared using p-Si single-crystal wafer substrates and employing thick-film techniques. Aluminum paste was used to obtain good ohmic contact to the silicon and silver; firing of the ITO was done at 650 C for 35 min. The thickness of the oxide layer was estimated to be about 60-100 A. Electrical and optical measurements indicated

  8. Instability of Si?F bonds in fluorinated silicon oxide (SiOF) films formed by various techniques

    Microsoft Academic Search

    Tetsuya Homma

    1996-01-01

    Instability of Si?F bonds in fluorinated silicon oxide (SiOF) films is studied. Al wiring corrosion and underlayer SiO2 etching problems are the major issues for the use of SiOF interlayer dielectric films. To clarify the mechanism, three kinds of SiOF films have been used for this study. They are: (i) a fluorinated silicon oxide (SiOF) film prepared by room-temperature chemical

  9. Quantum Conductance in Silicon Oxide Resistive Memory Devices

    PubMed Central

    Mehonic, A.; Vrajitoarea, A.; Cueff, S.; Hudziak, S.; Howe, H.; Labbé, C.; Rizk, R.; Pepper, M.; Kenyon, A. J.

    2013-01-01

    Resistive switching offers a promising route to universal electronic memory, potentially replacing current technologies that are approaching their fundamental limits. In many cases switching originates from the reversible formation and dissolution of nanometre-scale conductive filaments, which constrain the motion of electrons, leading to the quantisation of device conductance into multiples of the fundamental unit of conductance, G0. Such quantum effects appear when the constriction diameter approaches the Fermi wavelength of the electron in the medium – typically several nanometres. Here we find that the conductance of silicon-rich silica (SiOx) resistive switches is quantised in half-integer multiples of G0. In contrast to other resistive switching systems this quantisation is intrinsic to SiOx, and is not due to drift of metallic ions. Half-integer quantisation is explained in terms of the filament structure and formation mechanism, which allows us to distinguish between systems that exhibit integer and half-integer quantisation. PMID:24048282

  10. Silicon-oxide-assisted wear of a diamond-containing composite

    NASA Astrophysics Data System (ADS)

    Xiao, Huaping; Sinyukov, Alexander M.; He, Xingliang; Lin, Chih; Liang, Hong

    2013-12-01

    A composite containing diamond in silicon carbide substrate was studied for revealing wear mechanisms. Due to the low production cost, this material is being evaluated as an alternative economical solution in industry. Tribochemical examination was conducted using a pin-on-disk configuration in both aqueous and dry environments. Characterization was conducted on worn disks and wear debris. Phase transformation from diamond carbon (sp3) to graphite, tetrahedral carbon, or amorphous carbon (sp2) in friction was confirmed by Raman spectroscopy. In addition, the Raman peak of wear debris identified a shift from crystalline Si (521 cm-1) to the mixture of amorphous silicon and silicon oxide at 510 cm-1. The surface roughness of the diamond particles was found to be greatly reduced due to wear. The smoothening of the edges was due to polishing by silicon oxide as abrasives promoting removal of weaker sp2 bonded carbon. This research proposes a tribochemical wear mechanism of diamond that has significant benefits in the applications of automotive, aerospace, and energy industries.

  11. The influence of hydrogen on the growth of gallium catalyzed silicon oxide nanowires

    NASA Astrophysics Data System (ADS)

    Yan, X. Q.; Zhou, W. Y.; Sun, L. F.; Gao, Y.; Liu, D. F.; Wang, J. X.; Zhou, Z. P.; Yuan, H. J.; Song, L.; Liu, L. F.; Wang, G.; Xie, S. S.

    2005-05-01

    In this paper, we report that amorphous silicon oxide nanowires can be grown in a large quantity by chemical vapor deposition with molten gallium as the catalyst in a flow of mixture of SiH4, H2 and N2 at 600 °C. Meanwhile, when we grow these nanowires under the same conditions but without H2, octopus-like silicon oxide nanostructures are obtained. The reasons and mechanisms for the growth of these nanowires and nanostructures are discussed. Blue light emission is observed from SiOx nanowires, which can be attributed to defect centers of high oxygen deficiency. These SiOx nanowires may find applications in nanodevices and reinforcing composites.

  12. Temperature dependence of the electron-hole-plasma electroluminescence from metal-oxide-silicon tunneling diodes

    Microsoft Academic Search

    C. W. Liu; Miin-Jang Chen; I. C. Lin; M. H. Lee; Ching-Fuh Lin

    2000-01-01

    The temperature performance of metal-oxide-silicon tunneling light-emitting diodes was studied. An electron-hole-plasma model can be used to fit all the emission spectra from room temperature to 98 K. At constant voltage bias in the accumulation region, the normalized integral emission intensity slightly increases at low temperature with activation energy as low as 12 meV. From room temperature down to 98

  13. Ultrathin high-K metal oxides on silicon: processing, characterization and integration issues

    Microsoft Academic Search

    E. P Gusev; E Cartier; D. A Buchanan; M Gribelyuk; M Copel; H Okorn-Schmidt; C D’Emic

    2001-01-01

    An overview of our recent work on ultrathin (<100 Å) films of metal oxides deposited on silicon for advanced gate dielectrics applications will be presented. Data on ultrathin Al2O3, ZrO2, HfO2, and Y2O3 will be shown to illustrate the complex processing, integration and device-related issues for high dielectric constant (‘high-K’) materials. Both physical and electrical properties, as well as the

  14. Effects of silicon on defense of wheat against oxidative stress under drought at different developmental stages

    Microsoft Academic Search

    H. J. Gong; K. M. Chen; Z. G. Zhao; G. C. Chen; W. J. Zhou

    2008-01-01

    The effects of silicon application before sowing on the drought-induced oxidative stress and antioxidant defense in wheat\\u000a (Triticum aestivum L.) were investigated. Drought stress was applied by withholding watering till sampling at booting or filling stage. Application\\u000a of Si increased the water potential of drought-stressed plants at filling stage, whereas it did not at booting stage. The\\u000a superoxide dismutase (SOD)

  15. Properties of low dielectric constant fluorinated silicon oxide films prepared by plasma enhanced chemical vapor deposition

    Microsoft Academic Search

    Kihong Kim; Daehyuk Kwon; G. S. Lee

    1998-01-01

    The chemical and electrical properties of fluorinated silicon oxide films prepared by plasma enhanced chemical vapor deposition at 180°C were studied. The deposition of these films was made by incorporating CF4 as the fluorine source into the deposition process of SiO2 films using Si2H6 and N2O. With increasing CF4 flow, the deposition rate of these films decreased; meanwhile, the P-etch

  16. Optical properties of fluorinated silicon oxide films by liquid phase deposition for optical waveguides

    Microsoft Academic Search

    Tetsuya Homma; Atsushi Satoh; Seiji Okada; Masahiro Itoh; Masaki Yamaguchi; Hideo Takahashi

    1998-01-01

    Optical properties of fluorinated silicon oxide (SiOF) films for optical waveguide in optoelectronic devices were investigated. The SiOF films are formed at 25°C by a liquid phase deposition (LPD) technique using a supersaturated hydrofluosilicic acid (H2SiF 6) aqueous solution. Two main absorption peaks corresponding to Si-O and Si-F bonds were observed at the wavenumbers of 1090 and 930 cm-1 in

  17. The interaction of metals and barrier layers with fluorinated silicon oxides

    Microsoft Academic Search

    Sarah E. Kim; Christoph Steinbrüchel

    1999-01-01

    Fluorinated silicon oxide (FSG) films with varying fluorine (F) content were prepared by plasma-enhanced chemical vapor deposition (PECVD) using TEOS, O2, and either C2F6 or NF3. Metal films (Al, Cu–1% Al, Cu) were deposited on the FSG either directly or with a barrier layer (Ta, TaN) between the metal and the FSG. In addition, undoped PECVD SiO2 was studied as

  18. Silicon carbide coating to protect carbon\\/carbon composites against oxidation

    Microsoft Academic Search

    Qian-Gang Fu; He-Jun Li; Xiao-Hong Shi; Ke-Zhi Li; Guo-Dong Sun

    2005-01-01

    In order to protect carbon\\/carbon (C\\/C) composites from oxidation, a silicon carbide coating has been produced by a two-step pack cementation technique. XRD analysis showed that the inner coating obtained from the first step was a ?-SiC layer and the outer coating formed by the second step pack cementation was composed of ?-SiC, Si and ?-SiC. The as-received coating provided

  19. ${\\\\bf SiO}_{\\\\bm x}$ Nanowires Grown via the Active Oxidation of Silicon

    Microsoft Academic Search

    Avi Shalav; Taehyun Kim; Robert G. Elliman

    2011-01-01

    Amorphous, substoichiometric silica nanowires (NWs) can be grown on gold-coated silicon wafers by high- temperature annealing in an inert ambient with a low residual O2 partial pressure, consistent with conditions required for the active oxidation of the underlying Si substrate. The vapor precursor re- quired for NW growth is volatile SiO obtained directly from the reaction between the substrate and

  20. Growth mechanisms and properties of silicon oxides thermally grown in hydrogen-chlorine-oxygen ambients

    Microsoft Academic Search

    J. R. Monkowski

    1978-01-01

    Various analytical techniques were used to establish the relationships between the electrical and material properties of silicon oxides grown in chlorine-containing ambients. The capacitance-voltage technique yielded information on the electrical characteristics; transmission electron microscopy; scanning electron microscopy; scanning transmission electron microscopy; and ellipsometry elucidated the microstructural features; and infrared spectroscopy and X-ray fluorescence analysis produced data on the composition of

  1. Oxidation behavior of a ?-TiAl-based alloy implanted by silicon and\\/or carbon

    Microsoft Academic Search

    X. Y. Li; S. Taniguchi

    2005-01-01

    A study has been made of isothermal oxidation behavior of a ?-TiAl-based alloy, Ti–48Al–1.3Fe–1.1V–0.3B (at.%), implanted with silicon and\\/or carbon ions at 1173K, C+Si double implantation and following annealing at 1123K for 10.8ks. The isothermal oxidation was tested at 1173K for 349.2ks in air. Si or C implantation was carried out with a dose of 3.0×1021ions\\/m2 and at the acceleration

  2. Bismuth film electrodes for heavy metals determination

    NASA Astrophysics Data System (ADS)

    Rehacek, Vlastimil; Hotovy, Ivan; Vojs, Marian; Mika, Fedor

    2007-05-01

    Bismuth film electrodes (BiFEs) have a potential to replace toxic mercury used most frequently for determination of heavy metals (Cd, Pb, Zn) by anodic stripping voltammetry. We prepared a graphite disc electrode (0.5 mm in diameter) from a pencil-lead rod and developed a nitrogen doped diamond-like carbon (NDLC) microelectrode array consisting of 50 625 microdiscs with 3 ?m in diameter and interelectrode distances of 20 ?m on a highly conductive silicon substrate as a support for BiFEs. The disc graphite BiFE was used for simultaneous determination of Pb(II), Cd(II) and Zn(II) by square wave voltammetry (SWV) in an aqueous solution. We found the optimum bismuth-to-metal concentration ratio in the solution to be 20. The dependence of the stripping responses on the concentration of target metals was linear in the range from 1×10 -8 to 1.2×10 -7 mol/L. Detection limits 2.4×10 -9 mol/L for Pb(II), 2.9×10 -9 mol/L for Cd(II) and 1.2×10 -8 mol/L for Zn(II) were estimated. A bismuth-plated NDLC microelectrode array was used for Pb(II) determination by differential pulse voltammetry (DPV) in an aqueous solution. We found that the stripping current for bismuth-plated NDLC array was linear in the concentration range of Pb(II) from 2×10 -8 to 1.2×10 -7 mol/L. The detection limit 2.2×10 -8 mol/L was estimated from a calibration plot.

  3. Phase equilibria in the oxidation of impure silicon nitride

    Microsoft Academic Search

    R. O. Williams; V. J. Tennery

    1979-01-01

    The normal impurities in hot-pressed Si3N4 fabricated with MgO as an additive include Ca, Fe, WC, and SiO2. Within the bulk material the conditions are highly reducing, so the Fe and W will be in the reduced state. Thus the equilibrium oxide phases can be predicted from the CaO-MgO-SiO2 phase diagram suitably modified by the solubility of the Si3N4 in

  4. Dimensions of luminescent oxidized and porous silicon structures

    Microsoft Academic Search

    S. Schuppler; S. L. Friedman; M. A. Marcus; D. L. Adler; Y.-H. Xie; F. M. Ross; T. D. Harris; W. L. Brown; Y. J. Chabal; L. E. Brus; P. H. Citrin

    1994-01-01

    X-ray absorption measurements from H-passivated porous Si and from oxidized Si nanocrystals, combined with electron microscopy, ir absorption, [alpha] recoil, and luminescence emission data, provide a consistent structural picture of the species responsible for the visible luminescence observed in these samples. The mass-weighted average structures in por-Si are particles, not wires, with dimensions significantly smaller than previously reported or proposed.

  5. Interface studies of tungsten gate metal-oxide-silicon capacitors

    Microsoft Academic Search

    Huiling Shang; Marvin H. White; Kathryn W. Guarini; Paul Solomon; Eduard Cartier; Fenton R. McFeely; John J. Yurkas; Wen-Chin Lee

    2001-01-01

    The Si\\/SiO2 interface in 100-nm-thick chemical vapor deposition (CVD) tungsten gate metal-oxide-semiconductor (MOS) structures exhibits high interface state densities (Dit0>5×1011\\/cm2 eV) after conventional forming gas anneals over varying temperatures and times. In this letter, we show this is a consequence of the low diffusivity and solubility of molecular hydrogen in tungsten and the high temperature CVD process. We have discovered

  6. FT IR spectroscopy of silicon oxide layers prepared with perchloric acid

    NASA Astrophysics Data System (ADS)

    Kopani, M.; Mikula, M.; Takahashi, M.; Rusnák, J.; Pin?ík, E.

    2013-03-01

    Chlorine oxidation is important methods for improvement of many properties such as passivation of mobile oxide charge, breakdown strength or enhancement of the minority-carrier lifetime in the underlying silicon. In this study we consider effects influencing the density of SiO2 layers formed by three different methods: thermal oxidation at 850 °C, low temperature oxidation method by use of nitric acid - HNO3 (NAOS) and HClO4 afterward passivated with KCN/HCN solutions. Thicknesses of SiO2 layers determined by both capacitance-voltage (C-V) and XPS revealed fast oxidation rate compared with samples prepared by thermal oxidation. FT IR measurement showed that all absorption spectra are almost similar. Higher absorption of the sample prepared in HClO4 was observed. No Sisbnd Cl bonds were visible. Calculated atomic density of the SiO2 layer obtained from IR measurements was lowest for sample formed in HClO4. Chlorine oxidation results in higher oxidation rate (higher thickness) and formation of stoichiometric SiO2 layer with lower density. Following KCN/HCN passivation causes formation of Sisbnd N, Sisbnd O and Sisbnd OH bonds at the expense of Sisbnd Cl bonds.

  7. Very small critical current spreads in Nb\\/Al-AlOx\\/Nb integrated circuits using low-temperature and low-stress ECR PECVD silicon oxide films

    Microsoft Academic Search

    Xiaofan Meng; Anupama Bhat; Theodore Van Duzer

    1999-01-01

    We have developed a new Nb\\/Al-AlOx\\/Nb IC process with very small critical current spread. Low-temperature and low-stress ECR (Electron Cyclotron Resonance) PECVD (Plasma Enhanced Chemical Vapor Deposition) silicon oxide films have been used in the Nb IC process for all dielectric insulating layers to replace e-beam evaporated silicon monooxide films and RF reactive sputtered silicon oxide. Since ECR PECVD silicon

  8. Silicon Oxide Etch Process To remove the areas of silicon dioxide unprotected by

    E-print Network

    Kim, Philip

    containing HF; HF WILL ETCH GLASS! 3. Know the oxide thickness on your substrate. Procedure: 1. Clean the substrate or wafer surface by rinsing with DI water; hold the sample with Teflon tweezers. 2. Before which is hydrophobic. Observe the backside of the wafer to confirm this effect for a few seconds. 6

  9. Buried oxide layers formed by oxygen implantation on screened oxide silicon wafers: structural analysis

    Microsoft Academic Search

    J. Samitier; S. Martinez; A. Pérez-Rodríguez; B. Garrido; J. R. Morante; A. M. Papon; J. Margail

    1993-01-01

    In this work the structural analysis of the buried oxide layers formed by high dose oxygen ion implantation into Si through a screen oxide layer and annealing has been performed by infrared absorption, X-ray photoelectron spectroscopy and ellipsometry measurements. The correlation between the measurements from the different techniques points out the high structural quality of the buried oxide layers from

  10. Oxidation of chemically-vapor-deposited silicon nitride and single-crystal silicon

    NASA Technical Reports Server (NTRS)

    Choi, Doo J.; Fischbach, David B.; Scott, William D.

    1989-01-01

    The present 1000 C and 1300 C oxidation tests on 111-oriented single-crystal Si and dense CVD Si3N4 notes the oxidation rates of the latter in wet O2, dry O2, wet inert gas, and steam atmosphere conditions to be several orders of magnitude lower than the rates for the former in identical atmospheric conditions. Although the parabolic rate constant for Si increased linearly as the water vapor pressure increased, the parabolic rate constant for Si3N4 exhibited a nonlinear dependency on water vapor pressure in the presence of O2. NO and NH3 formation at the reaction interface of Si3N4, and the counterpermeation of these reaction products, are noted to dominate reaction kinetics.

  11. Oxidation of silicon nitride sintered with rare-earth oxide additions

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    The effects of rare-earth oxide additions on the oxidation of sintered Si3N4 were examined. Insignificant oxidation occurred at 700 and 1000 C, with no evidence of phase instability. At 1370 C, the oxidation rate was lowest for Y2O3 and increased for additions of La2O3, Sm2O3, and CeO2, in that order. Data obtained from X-ray diffraction, electron microprobe analysis, and scanning electron microscopy indicate that oxidation occurs via diffusion of cationic species from Si3N4 grain boundaries.

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

    SciTech Connect

    Shen, L.; Liang, Z. C., E-mail: liangzc@mail.sysu.edu.cn; Liu, C. F.; Long, T. J.; Wang, D. L. [School of Physics and Engineering, Institute for Solar Energy Systems, Sun Yat-sen University, 510275, Guangzhou (China)] [School of Physics and Engineering, Institute for Solar Energy Systems, Sun Yat-sen University, 510275, Guangzhou (China)

    2014-02-15

    Control of the oxidation process is one key issue in producing high-quality emitters for crystalline silicon solar cells. In this paper, the oxidation parameters of pre-oxidation time, oxygen concentration during pre-oxidation and pre-deposition and drive-in time were optimized by using orthogonal experiments. By analyzing experimental measurements of short-circuit current, open circuit voltage, series resistance and solar cell efficiency in solar cells with different sheet resistances which were produced by using different diffusion processes, we inferred that an emitter with a sheet resistance of approximately 70 ?/? performed best under the existing standard solar cell process. Further investigations were conducted on emitters with sheet resistances of approximately 70 ?/? that were obtained from different preparation processes. The results indicate that emitters with surface phosphorus concentrations between 4.96 × 10{sup 20} cm{sup ?3} and 7.78 × 10{sup 20} cm{sup ?3} and with junction depths between 0.46 ?m and 0.55 ?m possessed the best quality. With no extra processing, the final preparation of the crystalline silicon solar cell efficiency can reach 18.41%, which is an increase of 0.4%{sub abs} compared to conventional emitters with 50 ?/? sheet resistance.

  13. Structural silicon nitride materials containing rare earth oxides

    DOEpatents

    Andersson, Clarence A. (Pittsburgh, PA)

    1980-01-01

    A ceramic composition suitable for use as a high-temperature structural material, particularly for use in apparatus exposed to oxidizing atmospheres at temperatures of 400 to 1600.degree. C., is found within the triangular area ABCA of the Si.sub.3 N.sub.4 --SiO.sub.2 --M.sub.2 O.sub.3 ternary diagram depicted in FIG. 1. M is selected from the group of Yb, Dy, Er, Sc, and alloys having Yb, Y, Er, or Dy as one component and Sc, Al, Cr, Ti, (Mg +Zr) or (Ni+Zr) as a second component, said alloy having an effective ionic radius less than 0.89 A.

  14. Complete suppression of boron transient-enhanced diffusion and oxidation-enhanced diffusion in silicon using localized

    E-print Network

    Complete suppression of boron transient-enhanced diffusion and oxidation-enhanced diffusionGexCy layer, to eliminate the enhancement of enhanced boron diffusion in silicon due to an oxidizing surface to reduce the diffusion of dopants. However, the enhancement of boron diffusion due to ion implant damage

  15. Silicon Metal-oxide-semiconductor Quantum Dots for Single-electron Pumping.

    PubMed

    Rossi, Alessandro; Tanttu, Tuomo; Hudson, Fay E; Sun, Yuxin; Möttönen, Mikko; Dzurak, Andrew S

    2015-01-01

    As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by quantum mechanical effects such as tunneling through single dopants, scattering via interface defects, and discrete trap charge states. However, progress in silicon technology has shown that these phenomena can be harnessed and exploited for a new class of quantum-based electronics. Among others, multi-layer-gated silicon metal-oxide-semiconductor (MOS) technology can be used to control single charge or spin confined in electrostatically-defined quantum dots (QD). These QD-based devices are an excellent platform for quantum computing applications and, recently, it has been demonstrated that they can also be used as single-electron pumps, which are accurate sources of quantized current for metrological purposes. Here, we discuss in detail the fabrication protocol for silicon MOS QDs which is relevant to both quantum computing and quantum metrology applications. Moreover, we describe characterization methods to test the integrity of the devices after fabrication. Finally, we give a brief description of the measurement set-up used for charge pumping experiments and show representative results of electric current quantization. PMID:26067215

  16. Electrorheological properties of polyaniline-vanadium oxide nanostructures suspended in silicone oil

    NASA Astrophysics Data System (ADS)

    Goswami, Sumita; Brehm, Tiago; Filonovich, Sergej; Cidade, Maria Teresa

    2014-10-01

    In the present work, organic/inorganic hybrid nanostructures comprised of polyaniline and vanadium oxide were synthesized via a simple hydrothermal technique. The polyaniline/vanadium oxide hybrid morphology was tailored from rods to spheres by controlling the relative concentration of the reactants. The synthesized composites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) for structural and morphological analyses. Electrorheological (ER) properties of the as-prepared nanocomposites suspended in silicone oil were investigated by a rotational viscometer under both steady and dynamic shear. The ER activity of the composite material suspensions showed higher ER effects for the product with the rod-like structures than for the product with the sphere-like structures. The typical ER behaviour showed by the polyaniline-vanadium oxide nanocomposites demonstrated their potential application as an ER smart material.

  17. Oxidative stress in bacteria (Pseudomonas putida) exposed to nanostructures of silicon carbide.

    PubMed

    Borkowski, Andrzej; Szala, Mateusz; Kowalczyk, Pawe?; C?apa, Tomasz; Naro?na, Dorota; Selwet, Marek

    2015-09-01

    Silicon carbide (SiC) nanostructures produced by combustion synthesis can cause oxidative stress in the bacterium Pseudomonas putida. The results of this study showed that SiC nanostructures damaged the cell membrane, which can lead to oxidative stress in living cells and to the loss of cell viability. As a reference, micrometric SiC was also used, which did not exhibit toxicity toward cells. Oxidative stress was studied by analyzing the activity of peroxidases, and the expression of the glucose-6-phosphate dehydrogenase gene (zwf1) using real-time PCR and northern blot techniques. Damage to nucleic acid was studied by isolating and hydrolyzing plasmids with the formamidopyrimidine [fapy]-DNA glycosylase (also known as 8-oxoguanine DNA glycosylase) (Fpg), which is able to detect damaged DNA. The level of viable microbial cells was investigated by propidium iodide and acridine orange staining. PMID:25965002

  18. Role of interfacial oxide in high-efficiency graphene-silicon Schottky barrier solar cells.

    PubMed

    Song, Yi; Li, Xinming; Mackin, Charles; Zhang, Xu; Fang, Wenjing; Palacios, Tomás; Zhu, Hongwei; Kong, Jing

    2015-03-11

    The advent of chemical vapor deposition (CVD) grown graphene has allowed researchers to investigate large area graphene/n-silicon Schottky barrier solar cells. Using chemically doped graphene, efficiencies of nearly 10% can be achieved for devices without antireflective coatings. However, many devices reported in past literature often exhibit a distinctive s-shaped kink in the measured I/V curves under illumination resulting in poor fill factor. This behavior is especially prevalent for devices with pristine (not chemically doped) graphene but can be seen in some cases for doped graphene as well. In this work, we show that the native oxide on the silicon presents a transport barrier for photogenerated holes and causes recombination current, which is responsible for causing the kink. We experimentally verify our hypothesis and propose a simple semiconductor physics model that qualitatively captures the effect. Furthermore, we offer an additional optimization to graphene/n-silicon devices: by choosing the optimal oxide thickness, we can increase the efficiency of our devices to 12.4% after chemical doping and to a new record of 15.6% after applying an antireflective coating. PMID:25685934

  19. Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications

    PubMed Central

    2013-01-01

    Quantum dots (QDs) interaction with living organisms is of central interest due to their various biological and medical applications. One of the most important mechanisms proposed for various silicon nanoparticle-mediated toxicity is oxidative stress. We investigated the basic processes of cellular damage by oxidative stress and tissue injury following QD accumulation in the gibel carp liver after intraperitoneal injection of a single dose of 2 mg/kg body weight Si/SiO2 QDs after 1, 3, and 7 days from their administration. QDs gradual accumulation was highlighted by fluorescence microscopy, and subsequent histological changes in the hepatic tissue were noted. After 1 and 3 days, QD-treated fish showed an increased number of macrophage clusters and fibrosis, while hepatocyte basophilia and isolated hepatolytic microlesions were observed only after substantial QDs accumulation in the liver parenchyma, at 7 days after IP injection. Induction of oxidative stress in fish liver was revealed by the formation of malondialdehyde and advanced oxidation protein products, as well as a decrease in protein thiol groups and reduced glutathione levels. The liver enzymatic antioxidant defense was modulated to maintain the redox status in response to the changes initiated by Si/SiO2 QDs. So, catalase and glutathione peroxidase activities were upregulated starting from the first day after injection, while the activity of superoxide dismutase increased only after 7 days. The oxidative damage that still occurred may impair the activity of more sensitive enzymes. A significant inhibition in glucose-6-phosphate dehydrogenase and glutathione-S-transferase activity was noted, while glutathione reductase remained unaltered. Taking into account that the reduced glutathione level had a deep decline and the level of lipid peroxidation products remained highly increased in the time interval we studied, it appears that the liver antioxidant defense of Carassius gibelio does not counteract the oxidative stress induced 7 days after silicon-based QDs exposure in an efficient manner. PMID:23718202

  20. White electroluminescence from C- and Si-rich thin silicon oxides

    SciTech Connect

    Jambois, O.; Garrido, B.; Pellegrino, P.; Carreras, Josep; Perez-Rodriguez, A.; Montserrat, J.; Bonafos, C.; BenAssayag, G.; Schamm, S. [EME, Departament d'Electronica, IN2UB, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Instituto de Microelectronica de Barcelona (IMB-CNM, CSIC), Bellaterra 08193, Barcelona (Spain); Nanomaterials Group, CEMES-CNRS, 29 rue J. Marvig, 31055 Toulouse (France)

    2006-12-18

    White electroluminescence from carbon- and silicon-rich silicon oxide layers is reported. The films were fabricated by Si and C ion implantation at low energy in 40 nm thick SiO{sub 2}, followed by annealing at 1100 deg. C. Structural and optical studies allow assigning the electroluminescence to Si nanocrystals for the red part of the spectrum, and to C-related centers for the blue and green components. The external efficiency has been estimated to 10{sup -4}%. Electrical characteristics show a Fowler-Nordheim behavior for voltages above 25 V, corresponding to the onset of electroluminescence. This suggests that light emission is related to the impact ionization of radiative centers.

  1. Preparation of a silicon heterojunction photodetector from colloidal indium oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Ismail, Raid A.; Ali, Abdulrahman K.; Hassoon, Khaleel I.

    2013-10-01

    A colloidal indium oxide (In2O3) nanoparticles (NPs) were synthesized by using a Q-switched Nd:YAG laser ablation of indium target in water at room temperature. Optical absorption and x-ray diffraction (XRD) investigation of the prepared samples confirm the formation of In2O3 NPs. A solution-processed silicon heterojunction photodetector, fabricated by drop cast film of colloidal In2O3 NPs onto n-type single crystal silicon wafer, is demonstrated. I-V characteristics of In2O3 NPs/Si heterojunction under dark and illumination conditions confirmed the rectifying behavior and the good photoresponse. The built-in-voltage was determined from the C-V measurements which revealed an abrupt junction.

  2. Effects of oxidation process on the tunneling barrier structures in room-temperature operating silicon single-electron transistors

    Microsoft Academic Search

    Masumi Saitoh; Tasuku Murakami; Toshiro Hiramoto

    2002-01-01

    We investigate the tunneling barrier structures in the room-temperature operating silicon single-electron transistors (SETs). The devices are fabricated in the form of the point-contact channel metal-oxide-semiconductor field-effect transistors with gate oxide formed by thermal oxidation or low-pressure chemical vapor deposition (LP-CVD). From the gate voltage and temperature dependence of the peak current in the SET characteristics, it is found that

  3. Nitric oxide-generating silicone as a blood-contacting biomaterial

    PubMed Central

    Amoako, Kagya A.; Cook, Keith E.

    2011-01-01

    Coagulation upon blood-contacting biomaterials remains a problem for short and long-term clinical applications. This study examined the ability of copper(II)-doped silicone surfaces to generate nitric oxide (NO) and locally inhibit coagulation. Silicone was doped with 3-micron copper (Cu(0)) particles yielding 3 to 10 weight percent (wt%) Cu in 70-?m thick Cu/Silicone polymeric matrix composites (Cu/Si PMCs). At 3, 5, 8 and 10 wt% Cu doping, the surface expression of Cu was 12.1 ± 2.8%, 19.7 ± 5.4%, 29.0 ± 3.8%, and 33.8 ± 6.5% respectively. After oxidizing Cu(0) to Cu(II) by spontaneous corrosion, NO flux, JNO (mol*cm?2*min?1), as measured by chemiluminescence, increased with surface Cu expression according to the relationship JNO =(1.63 %SACu ?0.81) ×10?11, R2 = 0.98 where %SACu is the percentage of surface occupied by Cu. NO flux at 10 wt% Cu was 5.35± 0.74 ×10?10 mol*cm?2*min?1. The clotting time of sheep blood exposed to these surfaces was 80 ± 13s with pure silicone and 339 ± 44s when 10 wt% Cu(II) was added. SEMs of coatings showed clots occurred away from exposed Cu-dendrites. In conclusion, Cu/Si PMCs inhibit coagulation in a dose-dependent fashion related to the extent of copper exposure on the coated surface. PMID:22036723

  4. Process for removal of water and silicon mu-oxides from chlorosilanes

    DOEpatents

    Tom, Glenn M. (New Milford, CT); McManus, James V. (Danbury, CT)

    1992-03-10

    A scavenger composition having utility for removal of water and silicon mu-oxide impurities from chlorosilanes, such scavenger composition comprising: (a) a support; and (b) associated with the support, one or more compound(s) selected from the group consisting of compounds of the formula: R.sub.a-x MCl.sub.x wherein: M is a metal selected from the group consisting of the monovalent metals lithium, sodium, and potassium; the divalent metals magnesium, strontium, barium, and calcium; and the trivalent metal aluminum; R is alkyl; a is a number equal to the valency of metal M; and x is a number having a value of from 0 to a, inclusive; and wherein said compound(s) of the formula R.sub.a-x MCl.sub.x have been activated for impurity-removal service by a reaction scheme selected from those of the group consisting of: (i) reaction of such compound(s) with hydrogen chloride to form a first reaction product therefrom, followed by reaction of the first reaction product with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y, wherein y is a number having a value of from 1 to 3, inclusive; and (ii) reaction of such compound(s) with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y wherein y is a number having a value of 1 to 3, inclusive. A corresponding method of making the scavenger composition, and of purifying a chlorosilane which contains oxygen and silicon mu-oxide impurities, likewise are disclosed, together with a purifier apparatus, in which a bed of the scavenger composition is disposed. The composition, purification process, and purifier apparatus of the invention have utility in purifying gaseous chlorosilanes which are employed in the semiconductor industry as silicon source reagents for forming epitaxial silicon layers.

  5. Composition, process, and apparatus, for removal of water and silicon mu-oxides from chlorosilanes

    DOEpatents

    Tom, Glenn M. (New Milford, CT); McManus, James V. (Danbury, CT)

    1991-10-15

    A scavenger composition having utility for removal of water and silicon mu-oxide impurities from chlorosilanes, such scavenger composition comprising: (a) a support; and (b) associated with the support, one or more compound(s) selected from the group consisting of compounds of the formula: R.sub.a-x MCl.sub.x wherein: M is a metal selected from the group consisting of the monovalent metals lithium, sodium, and potassium; the divalent metals magnesium, strontium, barium, and calcium; and the trivalent metal aluminum; R is alkyl; a is a number equal to the valency of metal M; and x is a number having a value from 0 to a, inclusive; and wherein said compound(s) of the formula R.sub.a-x MCl.sub.x have been activated for impurity-removal service by a reaction scheme selected from those of the group consisting of: (i) reaction of such compound(s) with hydrogen chloride to form a first reaction product therefrom, followed by reaction of the first reaction product with a chlorosilane of the formula: SiH.sub.4"y Cl.sub.y, wherein y is a number having a value of from 1 to 3, inclusive; and (ii) reaction of such compound(s) with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y wherein y is a number having a value of 1 to 3, inclusive. A corresponding method of making the scavenger composition, and of purifying a chlorosilane which contains oxygen and silicon mu-oxide impurities, likewise are disclosed, together with a purifier apparatus, in which a bed of the scavenger composition is disposed. The composition, purification process, and purifier apparatus of the invention have utility in purifying gaseous chlorosilanes which are employed in the semiconductor industry as silicon source reagents for forming epitaxial silicon layers.

  6. Reliability of potassium ion electret in silicon oxide for vibrational energy harvester applications

    NASA Astrophysics Data System (ADS)

    Misawa, Kensuke; Sugiyama, Tatsuhiko; Hashiguchi, Gen; Toshiyoshi, Hiroshi

    2015-06-01

    In this paper, we report on the long-term reliability of potassium ion electret included in a thermally grown silicon oxide. The electret in this work is used in a microelectromechanical systems (MEMS) energy harvester to generate electrical current from mechanical vibration. A spring-mass system similar to a comb-drive electrostatic actuator is developed by silicon micromachining, and the surface is oxidized by wet-oxidation through a potassium hydroxide bubbler, thereby including potassium atoms at a high concentration. The potassium is then electrically polarized by an applied voltage of 150 V at 650 °C for 5 min. Degradation of the stored polarization potential is monitored in a vacuum of 1 × 10?3 Pa at elevated temperatures of 350, 400, and 450 °C. The time needed to cause a ?1 dB decay of the potential is used as the lifetime of the electret, and the Arrhenius extrapolation plot suggested a life time of more than 400 years at 25 °C.

  7. Influence of van der Waals interactions on morphology and dynamics in ultrathin liquid films at silicon oxide interfaces

    E-print Network

    Daniela Täuber; Ines Trenkmann; Christian von Borczyskowski

    2015-06-26

    Single molecule tracer diffusion studies of evaporating (thinning) ultrathin tetrakis-2-ethyl-hexoxysilane (TEHOS) films on silicon with 100 nm thermal oxide reveal a considerable slowdown of the molecular mobility within less than 4 nm above the substrate (corresponding to a few molecular TEHOS layers). This is related to restricted mobility and structure formation of the liquid in this region, in agreement with information obtained from a long-time ellipsometric study of thinning TEHOS films on silicon substrates with 100 nm thermal or 2 nm native oxide. Both show evidence for the formation of up to four layers. Additionally, on thermal oxide, a lateral flow of the liquid is observed, while the film on the native oxide forms an almost flat surface and shows negligible flow. Thus, on the 2 nm native oxide the liquid mobility is even more restricted in close vicinity to the substrate as compared to the 100 nm thermal oxide. In addition, we found a significantly smaller initial film thickness in case of the native oxide under similar dipcoating conditions. We ascribe these differences to van der Waals interactions with the underlying silicon in case of the native oxide, whereas the thermal oxide suffices to shield those interactions.

  8. Anti-reflection zinc oxide nanocones for higher efficiency thin-film silicon solar cells

    E-print Network

    Mailoa, Jonathan P

    2012-01-01

    Thin film silicon solar cells, which are commonly made from microcrystalline silicon ([mu]c-Si) or amorphous silicon (a-Si), have been considered inexpensive alternatives to thick polycrystalline silicon (polysilicon) solar ...

  9. Bismuth nitrate pentahydrate-induced novel nitration of eugenol

    PubMed Central

    2011-01-01

    Background Eugenol, the main constituent of clove oil possesses a number of medicinal activities. To enhance the medicinal property, structural modification is required. On the other hand, bismuth nitrate pentahydrate has been established as an excellent eco-friendly nitrating agent for several classes of organic compounds. Results Bismuth nitrate pentahydrate-induced nitration of eugenol has been investigated very thoroughly. Twenty five different conditions have been studied. The microwave-induced solvent-free reaction has been identified as the best condition. Conclusions Spectral analyses confirm that 5-nitroeugenol is the sole product in all the cases. No oxidized or isomerized product could be detected. PMID:22373430

  10. Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts

    SciTech Connect

    Yokota, S.H.

    1992-12-01

    Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxidation behavior of the alloy compact is different from the model proposed for the pure Al/alumina system.

  11. Novel silicon metal-oxide semiconductor devices for molecular sensing and hot electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Jinman

    This dissertation describes results from a novel hybrid molecular/metal-oxide-semiconductor field effect transistor (MOSFET). The device consists of a buried channel silicon-on-insulator MOSFET with a molecular monolayer attached to its surface. The device is made using a 2 mum minimum gate length, silicon MOSFET process developed in Arizona State University. A hybrid molecular/MOSFET structure that is sensitive to the presence of a molecular monolayer on its surface was fabricated and characterized. The device was fabricated from a silicon-on-insulator (SOI) substrate. A substrate voltage was used to invert the buried Si:SiO 2 interface in this device. This allowed the top surface of the silicon to be free of any insulating layers, apart from a thin native oxide that forms on exposure to air. The buried inversion layer was less than 40 nm away from the exposed surface, and the threshold voltage of the device was strongly influenced by the surface potential. Measurements of the drain current as a function of substrate voltage can be accurately reproduced from numerical simulation by treating the charge at the native oxide interface as a fitting parameter. A large shift in the threshold voltage occurring after attachment of the molecular monolayer was observed, which was explained by molecular protonation of the native oxide. A split gate SOI device structure was also developed and fabricated to improve the sensitivity of the hybrid molecular/MOSFET. Because of its very small size, the nano-scale hybrid device will be susceptible to hot carrier effects. Numerical simulation of a 100nm x 100nm split gate device showed high electron velocity at the drain end of the channel. A novel scanning probe technique is suggested as a way of measuring the hot electron distribution in the channel of the split gate structure. This structure is also suitable for hot electron spectroscopy in ultra short channel MOSFETs because it resembles a conventional MOSFET and its inversion channel is close to the ambient and therefore accessible with the tip of a scanning probe microscope.

  12. Graphoepitaxy of sexithiophene on thermally oxidized silicon surface with artificial periodic grooves

    SciTech Connect

    Ikeda, Susumu; Saiki, Koichiro; Tsutsui, Ken; Edura, Tomohiko; Wada, Yasuo; Miyazoe, Hiroyuki; Terashima, Kazuo; Inaba, Katsuhiko; Mitsunaga, Toru; Shimada, Toshihiro [Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8561 (Japan); Nanotechnology Research Laboratory, Waseda University, Wasedatsurumaki-cho, Shinjuku-ku, Tokyo 162-0041 (Japan); Department of Advanced Materials Science, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8561 (Japan); Rigaku Corporation, 3-9-12 Matsubara-cho, Akishima, Tokyo 196-8666 (Japan); Department of Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2006-06-19

    Graphoepitaxial growth of a sexithiophene (6T) thin film was achieved on a thermally oxidized silicon surface with artificial periodic grooves. The surface structure was fabricated by electron beam lithography and the thin film was grown by molecular beam deposition. A well-pronounced, in-plane oriented component ([010]{sub 6T} parallel grooves) was identified by grazing incidence x-ray diffraction, though there also existed some randomly oriented 6T grains. Presence of the graphoepitaxial component was also confirmed by results of the orientational analysis of atomic force microscopy images. It was shown that the in-plane orientation control of organic semiconductors is possible using graphoepitaxy.

  13. Heterogeneously integrated organic light-emitting diodes with complementary metal-oxide-silicon circuitry

    Microsoft Academic Search

    D. L. Mathine; H. S. Woo; W. He; T. W. Kim; B. Kippelen; N. Peyghambarian

    2000-01-01

    Top-emitting arrays of organic light-emitting diodes (OLEDs) have been fabricated and demonstrated on complementary metal-oxide-silicon (CMOS) circuitry. The 8×8 array of OLEDs is composed of 90 mum micropixels with a 55 mum separation. The OLEDs are based on an emitting layer of tris-(8-hydroxyquinoline)aluminum (Alq3) doped with coumarin 6 to provide green light emission. A layer of N,N'-diphenyl-N, N'-bis(3-methylphenyl)1-1'-biphenyl 1-4, 4'-diamine

  14. Structure characterization of carbon and fluorine-doped silicon oxide films with low dielectric constant

    Microsoft Academic Search

    Shi-Jin Ding; Li Chen; Xin-Gong Wan; Peng-Fei Wang; Jian-Yun Zhang; David Wei Zhang; Ji-Tao Wang

    2001-01-01

    Carbon and fluorine-doped silicon oxide (SiO2:C,F) films with low dielectric constant have been deposited from tetraethoxysilane (TEOS), C4F8 and Ar using plasma enhanced chemical vapor deposition (PECVD) method. X-ray diffraction (XRD) analysis shows that SiO2:C,F film is amorphous. Fourier transform infrared (FTIR) spectra illustrate that the intense absorption band between l000 and 1300cm?1 becomes broader with increasing C4F8 flow rate

  15. Thermo-Optic Switch using Fluorinated Silicon Oxide and Organic Spin-on-Glass Films

    Microsoft Academic Search

    Hiroyasu Kondo; Kazuaki Inohara; Yuki Taniguchi; Junko Nakahata; Tetsuya Homma; Hideo Takahashi

    2001-01-01

    A thermo-optic switch in a thin-film optical waveguide was investigated. Fluorinated silicon oxide (SiOF) and organic spin-on-glass (SOG) films were used as core-layer and clad-layer, respectively, in the waveguide structure. The SiOF films were formed at 23#x00B0;C by a liquid-phase deposition (LPD) technique using a supersaturated hydrofluosilicic acid (H2SiF6) aqueous solution. Thermal coefficients of the refractive indices for LPD-SiOF and

  16. TiO2 and HfO2 in electrolyte-oxide-silicon configuration for applications in bioelectronics

    NASA Astrophysics Data System (ADS)

    Wallrapp, Frank; Fromherz, Peter

    2006-06-01

    We study the electrical properties of thin TiO2 films made by atomic layer deposition (ALD) on p-doped silicon in an electrolyte-oxide-silicon (EOS) configuration. The electrolyte contact of the TiO2/Si heterostructure allows measurements of the differential capacitance for a wide range of bias voltages as they cannot be performed in a metal-oxide-silicon structure because of extensive leakage currents. In the accumulation region of p-silicon, we find a saturation of capacitance that decreases with oxide thickness, indicating an insulator with a dielectric constant of 34. In the inversion region of p-silicon, the capacitance increases in two steps far beyond the saturation capacitance. We assign this effect to the presence of electrons in TiO2 which is controlled by the bias voltage and by immobile positive charges at the TiO2/Si interface: When the Fermi energy in p-silicon is raised to the level of the low lying conduction band of TiO2, electrons accumulate in two layers near the TiO2/Si interface and at the electrolyte/TiO2 interface with a concomitantly enhanced differential capacitance. As a control, we study HfO2 films also made by ALD. We obtain a dielectric constant of 15 from the capacitance in the accumulation region of p-silicon. For HfO2 with a high lying conduction band, the capacitance decreases as expected in the inversion region for the high-frequency limit of silicon. The electrical characterization of TiO2 and HfO2 in EOS junctions opens future applications of high-? materials in bioelectronics for efficient capacitive interaction of silicon chips and living cells.

  17. Densification of chemical vapor deposition silicon dioxide film using oxygen radical oxidation

    SciTech Connect

    Kawase, Kazumasa; Uehara, Yasushi [Advanced Technology R and D Center, Mitsubishi Electric Corporation, 8-1-1 Tsukaguchi-honmachi, Amagasaki, Hyogo 661-8661 (Japan); Teramoto, Akinobu; Suwa, Tomoyuki; Hattori, Takeo; Ohmi, Tadahiro [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Umeda, Hiroshi [Process Technology Div., Production and Technology Unit, RENESAS Electronics Corporation, 751 Horiguchi, Hitachinaka, Ibaraki 312-8504 (Japan)

    2012-02-01

    Silicon dioxide (SiO{sub 2}) films formed by chemical vapor deposition (CVD) were treated with oxygen radical oxidation using Ar/O{sub 2} plasma excited by microwave. The mass density depth profiles, carrier trap densities, and current-voltage characteristics of the radical-oxidized CVD-SiO{sub 2} films were investigated. The mass density depth profiles were estimated with x ray reflectivity measurement using synchrotron radiation of SPring-8. The carrier trap densities were estimated with x ray photoelectron spectroscopy time-dependent measurement. The mass densities of the radical-oxidized CVD-SiO{sub 2} films were increased near the SiO{sub 2} surface. The densities of the carrier trap centers in these films were decreased. The leakage currents of the metal-oxide-semiconductor capacitors fabricated by using these films were reduced. It is probable that the insulation properties of the CVD-SiO{sub 2} film are improved by the increase in the mass density and the decrease in the carrier trap density caused by the restoration of the Si-O network with the radical oxidation.

  18. Encapsulation of Au Nanoparticles on a Silicon Wafer During Thermal Oxidation

    PubMed Central

    2013-01-01

    We report the behavior of Au nanoparticles anchored onto a Si(111) substrate and the evolution of the combined structure with annealing and oxidation. Au nanoparticles, formed by annealing a Au film, appear to “float” upon a growing layer of SiO2 during oxidation at high temperature, yet they also tend to become partially encapsulated by the growing silica layers. It is proposed that this occurs largely because of the differential growth rates of the silica layer on the silicon substrate between the particles and below the particles due to limited access of oxygen to the latter. This in turn is due to a combination of blockage of oxygen adsorption by the Au and limited oxygen diffusion under the gold. We think that such behavior is likely to be seen for other metal–semiconductor systems. PMID:24163715

  19. Water absorption and interface reactivity of yttrium oxide gate dielectrics on silicon

    NASA Astrophysics Data System (ADS)

    Niu, D.; Ashcraft, R. W.; Parsons, G. N.

    2002-05-01

    High dielectric constant insulators deposited at low temperatures rapidly absorb water during exposure to the atmosphere, and the resulting OH leads to detrimental interface reactions. We report the effect of atmospheric exposure on ultrathin yttrium oxide, and details of silicon substrate reactions during postdeposition anneals. Infrared absorption analysis indicates significant absorption of water vapor during atmospheric exposure, even for very short times (<15 min). X-ray photoelectron spectroscopy demonstrates that after OH absorption, a thermally activated interface reaction proceeds with an activation energy of 0.33 eV, consistent with substrate reaction with OH present in the film. The OH absorption rate is reduced for annealed films or when capping layers are deposited in situ. Similar oxidation processes are expected to occur in other high-k materials of interest, where the rate of OH absorption will depend on the deposition process and material thermal history.

  20. Charge separation technique for metal-oxide-silicon capacitors in the presence of hydrogen deactivated dopants

    SciTech Connect

    WITCZAK,STEVEN C.; WINOKUR,PETER S.; LACOE,RONALD C.; MAYER,DONALD C.

    2000-02-01

    An improved charge separation technique for metal-oxide-silicon (MOS) capacitors is presented which accounts for the deactivation of substrate dopants by hydrogen at elevated irradiation temperatures or small irradiation biases. Using high-frequency capacitance-voltage (C-V) measurements, radiation-induced inversion voltage shifts are separated into components due to oxide trapped charge, interface traps and deactivated dopants, where the latter is computed from a reduction in Si capacitance. In the limit of no radiation-induced dopant deactivation, this approach reduces to the standard midgap charge separation technique used widely for the analysis of room-temperature irradiations. The technique is demonstrated on a p-type MOS capacitor irradiated with {sup 60}Co {gamma}-rays at 100 C and zero bias, where the dopant deactivation is significant.

  1. Characterization of ion species of silicon oxide films using positive and negative secondary ion mass spectra

    NASA Astrophysics Data System (ADS)

    Chiba, Kiyoshi; Nakamura, Shun

    2006-11-01

    Secondary ion species of silicon oxide films have been investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Characterization of thermally grown SiO 2 films on silicon has been performed. A diagram showing secondary ion spectra of SiO 2 films in both positive and negative polarities indicates the pattern of change in polarities and intensities of ion species from SiO + to Si 5O 11-. The ions mostly change from positive to negative polarity between Si nO 2 n-1 and Si nO 2 n. Ion peaks with the strongest intensities in the respective cluster ions correspond to the Si nO 2 n+1 negative ion. Intensities of ion species of Si nO 2 n+2 appear negligibly small. Ion species of Si 3O +, Si 3O 2+ and Si 3O 3+ have been found at the interface between silicon and SiO 2 films. The intensity patterns of these ion species compared to those of SiO 2 films indicate that most of these species are not emitted from the SiO 2 films, but likely from the SiO structures.

  2. 1 DIMARIA,D. J., and KERR, D. R.: 'Interface effects and high conduc-tivity in oxides grown from polycrystalline silicon', Appl. Phys.

    E-print Network

    Mitchell, Chris

    grown from polycrystalline silicon', Appl. Phys. Lett., 1975,21, pp. 505-507 ANDERSON, R. M., and KERR of nitrided thermal oxide grown on polycrystalline silicon', Appl. Phys. Lett., 1986,48, pp. 165167 4 ALVI, N, D. R .: 'Evidence for surface asperity mechanism of conductivity in oxide grown on polycrystalline

  3. Characterization of silicon oxide gas barrier films with controlling to the ion current density (ion flux) by plasma enhanced chemical vapor deposition

    Microsoft Academic Search

    Su B. Jin; Youn J. Kim; Yoon S. Choi; In S. Choi; Jeon G. Han

    2010-01-01

    Silicon oxide gas barrier films were deposited on polyethylene terephthalate (PET) substrates by plasma enhanced chemical vapor deposition (PE-CVD) for applications to transparent barrier packaging. The barrier properties of the silicon oxide coated film were optimized by varying the bias conditions and input power in the radio frequency plasma. The plasma diagnostics, ion current density and substrate temperature were characterized

  4. Silicon carbide: A unique platform for metal-oxide-semiconductor physics

    NASA Astrophysics Data System (ADS)

    Liu, Gang; Tuttle, Blair R.; Dhar, Sarit

    2015-06-01

    A sustainable energy future requires power electronics that can enable significantly higher efficiencies in the generation, distribution, and usage of electrical energy. Silicon carbide (4H-SiC) is one of the most technologically advanced wide bandgap semiconductor that can outperform conventional silicon in terms of power handling, maximum operating temperature, and power conversion efficiency in power modules. While SiC Schottky diode is a mature technology, SiC power Metal Oxide Semiconductor Field Effect Transistors are relatively novel and there is large room for performance improvement. Specifically, major initiatives are under way to improve the inversion channel mobility and gate oxide stability in order to further reduce the on-resistance and enhance the gate reliability. Both problems relate to the defects near the SiO2/SiC interface, which have been the focus of intensive studies for more than a decade. Here we review research on the SiC MOS physics and technology, including its brief history, the state-of-art, and the latest progress in this field. We focus on the two main scientific problems, namely, low channel mobility and bias temperature instability. The possible mechanisms behind these issues are discussed at the device physics level as well as the atomic scale, with the support of published physical analysis and theoretical studies results. Some of the most exciting recent progress in interface engineering for improving the channel mobility and fundamental understanding of channel transport is reviewed.

  5. Oxidized Porous Silicon Particles Covalently Grafted with Daunorubicin as a Sustained Intraocular Drug Delivery System

    PubMed Central

    Chhablani, Jay; Nieto, Alejandra; Hou, Huiyuan; Wu, Elizabeth C.; Freeman, William R.; Sailor, Michael J.; Cheng, Lingyun

    2013-01-01

    Purpose. To test the feasibility of covalent loading of daunorubicin into oxidized porous silicon (OPS) and to evaluate the ocular properties of sustained delivery of daunorubicin in this system. Methods. Porous silicon was heat oxidized and chemically functionalized so that the functional linker on the surface was covalently bonded with daunorubicin. The drug loading rate was determined by thermogravimetric analysis. Release of daunorubicin was confirmed in PBS and excised rabbit vitreous by mass spectrometry. Daunorubicin-loaded OPS particles (3 mg) were intravitreally injected into six rabbits, and ocular properties were evaluated through ophthalmic examinations and histology during a 3-month study. The same OPS was loaded with daunorubicin using physical adsorption and was evaluated similarly as a control for the covalent loading. Results. In the case of covalent loading, 67 ± 10 ?g daunorubicin was loaded into each milligram of the particles while 27 ± 10 ?g/mg particles were loaded by physical adsorption. Rapid release of daunorubicin was observed in both PBS and excised vitreous (?75% and ?18%) from the physical adsorption loading, while less than 1% was released from the covalently loaded particles. Following intravitreal injection, the covalently loaded particles demonstrated a sustained degradation of OPS with drug release for 3 months without evidence of toxicity; physical adsorption loading revealed a complete release within 2 weeks and localized retinal toxicity due to high daunorubicin concentration. Conclusions. OPS with covalently loaded daunorubicin demonstrated sustained intravitreal drug release without ocular toxicity, which may be useful to inhibit unwanted intraocular proliferation. PMID:23322571

  6. Thermal stability of uniform silver clusters prepared on oxidized silicon and aluminum surfaces by electron beam lithography in oxidizing and reducing ambients

    Microsoft Academic Search

    M. X. Yang; P. W. Jacobs; C. Yoon; L. Muray; E. Anderson; D. T. Attwood; G. A. Somorjai

    1997-01-01

    100 and 750 nm silver nanoclusters are fabricated on oxidized silicon and aluminum surfaces by electron beam lithography.\\u000a Silver nanoclusters are characterized by atomic force microscopy, scanning electron microscopy, scanning Auger electron microscopy\\u000a and high-resolution optical microscopy. The ordered structure of silver nanoclusters facilitates a thermal stability study\\u000a in both reducing and oxidizing conditions. In reducing conditions, silver clusters are

  7. Distribution of impurity elements in slag–silicon equilibria for oxidative refining of metallurgical silicon for solar cell applications

    Microsoft Academic Search

    M. D. Johnston; M. Barati

    2010-01-01

    The possibility of refining metallurgical grade silicon to a high-purity product for solar cell applications by the slagging of impurity elements was investigated. Distribution coefficients were determined for B, Ca, Mg, Fe, K and P between magnesia or alumina saturated Al2O3–CaO–MgO–SiO2 and Al2O3–BaO–SiO2 slags and silicon at 1500°C. The partitioning of the impurity elements between molten silicon and slag was

  8. Design, microstructure, and high-temperature behavior of silicon nitride sintered with rate-earth oxides

    SciTech Connect

    Ciniculk, M.K. (California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering)

    1991-08-01

    The processing-microstructure-property relations of silicon nitride ceramics sintered with rare-earth oxide additives have been investigated with the aim of improving their high-temperature behavior. The additions of the oxides of Y, Sm, Gd, Dy, Er, or Yb were compositionally controlled to tailor the intergranular phase. The resulting microstructure consisted of {beta}-Si{sub 3}N{sub 4} grains and a crystalline secondary phase of RE{sub 2}Si{sub 2}O{sub 7}, with a thin residual amorphous phase present at grain boundaries. The lanthanide oxides were found to be as effective as Y{sub 2}O{sub 3} in densifying Si{sub 3}N{sub 4}, resulting in identical microstructures. The crystallization behavior of all six disilicates was similar, characterized by a limited nucleation and rapid growth mechanism resulting in large single crystals. Complete crystallization of the intergranular phase was obtained with the exception of a residual amorphous, observed at interfaces and believed to be rich in impurities, the cause of incomplete devitrification. The low resistance to oxidation of these materials was attributed to the minimization of amorphous phases via devitrification to disilicates, compatible with SiO{sub 2}, the oxidation product of Si{sub 3}N{sub 4}. The strength retention of these materials at 1300{degrees}C was found to be between 80% and 91% of room-temperature strength, due to crystallization of the secondary phase and a residual but refractory amorphous grain-boundary phase. The creep behavior was found to be strongly dependent on residual amorphous phase viscosity as well as on the oxidation behavior, as evidenced by the nonsteady-state creep rates of all materials. 122 refs., 51 figs., 12 tabs.

  9. Numerically controlled atmospheric-pressure plasma sacrificial oxidation using electrode arrays for improving silicon-on-insulator layer uniformity

    NASA Astrophysics Data System (ADS)

    Takei, Hiroyasu; Yoshinaga, Keinosuke; Matsuyama, Satoshi; Yamauchi, Kazuto; Sano, Yasuhisa

    2015-01-01

    Silicon-on-insulator (SOI) wafers are important semiconductor substrates in high-performance devices. In accordance with device miniaturization requirements, ultrathin and highly uniform top silicon layers (SOI layers) are required. A novel method involving numerically controlled (NC) atmospheric-pressure plasma sacrificial oxidation using an electrode array system was developed for the effective fabrication of an ultrathin SOI layer with extremely high uniformity. Spatial resolution and oxidation properties are the key factors controlling ultraprecision machining. The controllability of plasma oxidation and the oxidation properties of the resulting experimental electrode array system were examined. The results demonstrated that the method improved the thickness uniformity of the SOI layer over one-sixth of the area of an 8-in. wafer area.

  10. Microstructure of epitaxial ferroelectric/metal oxide electrode thin film heterostructures on LaAlO{sub 3} and silicon

    SciTech Connect

    Ghonge, S.G.; Goo, E. [Univ. of Southern California, Los Angeles, CA (United States); Ramesh, R. [Bellcore, Red Bank, NJ (United States); Haakenaasen, R.; Fork, D.K. [Xerox Palo Alto Research Center, CA (United States)

    1994-12-31

    TEM and X-ray diffraction studies of PZT, PLZT, lead titanate and bismuth titanate ferroelectric thin films and YBa{sub 2}Cu{sub 3}O{sub 7{minus}x}(YBCO), Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}(BSCCO) and La{sub 0.5}Sr{sub 0.5}CoO{sub 3}(LSCO) electrically conductive oxide thin films, that are sequentially deposited by pulsed laser ablation, show that these films may be deposited epitaxially onto LaAlO{sub 3}(LAO) or Si substrates. The conductive oxides are promising candidates for use is electrodes in place of metal electrodes in integrated ferroelectric device applications. The oxide electrodes are more chemically compatible with the ferroelectric films. High resolution electron microscopy his been used to investigate the interface between the ferroelectric and metal oxide thin films and no reaction was detected. Epitaxial growth is possible due to the similar crystal structures and the small lattice mismatch. The lattice mismatch that is present causes the domains in the ferroelectric films to be preferentially oriented and in the case of lead titanate, the film is single domain. These films may also have potential applications in integrated optical devices.

  11. Design, fabrication and optical characterization of cerium oxide-magnesium fluoride double layer antireflection coatings on monocrystalline silicon substrates

    Microsoft Academic Search

    Tadeusz Wiktorczyk; Micha? Ole?

    2007-01-01

    Theoretical and experimental studies of a double layer antireflection coating deposited onto silicon wafers have been carried out. Magnesium oxide and cerium oxide fabricated by physical vapor deposition method have been applied as low- and high-refractive index materials. MgF2–CeO2–Si structures exhibited the reflectivity below 3% in the wavelength window from 0.5?m to 1.2?m. Theoretical simulations of spectral characteristics of the

  12. High performance of graphene oxide-doped silicon oxide-based resistance random access memory

    PubMed Central

    2013-01-01

    In this letter, a double active layer (Zr:SiO x /C:SiO x ) resistive switching memory device with outstanding performance is presented. Through current fitting, hopping conduction mechanism is found in both high-resistance state (HRS) and low-resistance state (LRS) of double active layer RRAM devices. By analyzing Raman and FTIR spectra, we observed that graphene oxide exists in C:SiO x layer. Compared with single Zr:SiO x layer structure, Zr:SiO x /C:SiO x structure has superior performance, including low operating current, improved uniformity in both set and reset processes, and satisfactory endurance characteristics, all of which are attributed to the double-layer structure and the existence of graphene oxide flakes formed by the sputter process. PMID:24261454

  13. Corrosion by liquid lead and lead-bismuth: experimental results review and analysis

    SciTech Connect

    Zhang, Jinsuo [Los Alamos National Laboratory

    2008-01-01

    Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews corrosion by liquid lead and lead bismuth, including the corrosion mechanisms, corrosion inhibitor and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviors of steels in liquid lead and lead-bismuth are predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead bismuth as heat transfer media.

  14. A versatile sol-gel synthesis route to metal-silicon mixed oxide nanocomposites that contain metal oxides as the major phase

    SciTech Connect

    Clapsaddle, B J; Sprehn, D W; Gash, A E; Satcher, J H; Simpson, R L

    2003-12-08

    The general synthesis of metal-silicon mixed oxide nanocomposite materials, including a variety of both main group and transition metals, in which the metal oxide is the major component is described. In a typical synthesis, the metal oxide precursor, MCl{sub x}{times}{sub y}H{sub 2}O (x=3-6, y=0-7), was mixed with the silica precursor, tetramethylorthosilicate (TMOS), in ethanol and gelled using an organic epoxide. The successful preparation of homogeneous, monolithic materials depended on the oxidation state of the metal as well as the epoxide chosen for gelation. The composition of the resulting materials was varied from M/Si=1-5 (mol/mol) by adjusting the amount of TMOS added to the initial metal oxide precursor solution. Supercritical processing of the gels in CO{sub 2} resulted in monolithic, porous aerogel nanocomposite materials with surface areas ranging from 100 - 800 m{sup 2}/g. The bulk materials are composed of metal oxide/silica particles that vary in size from 5 - 20 nm depending on the epoxide used for gelation. Metal oxide and silica dispersion throughout the bulk material is extremely uniform on the nanoscale. The versatility and control of the synthesis method will be discussed as well as the properties of the resulting metal-silicon mixed oxide nanocomposite materials.

  15. Corrosion of ODS steels in lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Hosemann, P.; Thau, H. T.; Johnson, A. L.; Maloy, S. A.; Li, N.

    2008-02-01

    Oxide dispersion strengthened (ODS) ferritic steels are advanced materials being developed for high temperature applications. Their properties (high temperature strength, creep resistance, corrosion/oxidation resistance) make them potentially usable for high temperature applications in liquid metal cooled systems like liquid lead-bismuth eutectic cooled reactors and spallation sources. Corrosion tests on five different ODS alloys were performed in flowing liquid lead-bismuth eutectic in the DELTA Loop at the Los Alamos National Laboratory at 535 °C for 200 h and 600 h. The tested materials were chromium alloyed ferritic/martensitic steels (12YWT, 14YWT, MA957) and Cr-Al alloyed steels (PM2000, MA956). It was shown that the Al alloyed ODS steel above 5.5 wt% Al (PM2000) is highly resistant to corrosion and oxidation in the conditions examined, and that the corrosion properties of the ODS steels depend strongly on their grain size.

  16. Fabrication of Textured Bismuth Sodium Titanate Using Excess Bismuth Oxide

    Microsoft Academic Search

    Toshio Kimura; Eiichiro Fukuchi; Toshihiko Tani

    2005-01-01

    Bi0.5Na0.5TiO3 (BNT) bulk ceramics with a preferred orientation (texture) were prepared by the reactive-templated grain growth method using platelike Bi4Ti3O12 (BiT) particles as templates for BNT. The texture did not develop extensively in stoichiometric BNT, but the addition of excess Bi2O3 to BNT enhanced the texture development. The role of excess Bi2O3 was examined. The calcined compacts were composed of

  17. Characterization of the silicon oxide thin films deposited on polyethylene terephthalate substrates by radio frequency reactive magnetron sputtering

    Microsoft Academic Search

    M.-C. Lin; C.-H. Tseng; L.-S. Chang; D.-S. Wuu

    2007-01-01

    Transparent silicon oxide films were deposited on polyethylene terephthalate substrates by means of reactive magnetron sputtering with a mixture of argon and oxygen gases. The influences of process parameters, including the oxygen flow ratio, work pressure, radio frequency (RF) power density and deposition time, on the film properties, such as: deposition rate, morphology, surface roughness, water vapor\\/oxygen transmission rate and

  18. hal-00087421,version2-21Dec2006 The interface between a polar perovskite oxide and silicon from

    E-print Network

    Paris-Sud XI, Université de

    hal-00087421,version2-21Dec2006 The interface between a polar perovskite oxide and silicon from). Many of them belong to the class of perovskites (cubic crystals whose chemical formula is ABO3) which structure. In the search of the best candidate, the LaAlO3 crystal raised out of the perovskite family

  19. Abnormal increase of time of oxygen diffusion with oxidation of silicon surface under action of powerful laser pulses

    Microsoft Academic Search

    Alexander F. Banishev; Vladimir S. Golubev; Alexei Y. Kremnev

    2000-01-01

    The paper presents an investigation of deformation response of monocrystalline silicon surface to the action of short laser pulses in the air and in vacuum P approximately equals 10-2 Torr. An anomalously continuous change of the surface relief was identified on irradiation in the air. The observable phenomenon is explained by oxidation of surface layer, enriched with defects.

  20. Carrier transport mechanism in indium tin oxide (ITO)/silicon heterojunctions: effect of chlorine

    NASA Astrophysics Data System (ADS)

    Vasu, V.; Subrahmanyam, A.

    2005-02-01

    Transparent-conducting-oxide (TCO)-based photovoltaic junctions have shown complexity in the transport phenomena at the interface. The present study is an attempt to understand the effect of chlorine at the interface between indium tin oxide (ITO) and Si. The ITO/Si junctions have been prepared by depositing transparent and conducting tin-doped indium oxide (ITO) thin films on as-cleaned and chlorine-treated single-crystal p-type and n-type silicon substrates using the reactive electron-beam evaporation technique. ITO/n-Si junctions have shown photovoltaic properties. The photoconversion efficiency of these junctions is observed to increase from 2.3% to 5.5% under chlorine treatment. The transport mechanism across these junctions has been studied by current voltage (I V , both dark and illuminated) and capacitance voltage (C V ) characterisation techniques. The carrier transport mechanism is found to be dominated by recombination at the depletion region for the junctions prepared with chlorine treatment, whereas for the other junctions, the thermionic process seems to be prominent. The unrealistic barrier heights observed in these junctions by the C V technique confirms the complex nature of the interface.

  1. ac impedance measurements of moisture in interfaces between epoxy and oxidized silicon

    NASA Astrophysics Data System (ADS)

    Takahashi, Ken M.

    1990-04-01

    In situ interfacial impedance measurements are used to study the effects of moisture at 80 °C on the interface between oxidized silicon and a diglycidyl ether of bisphenol A epoxy cured with diethylene triamine. Bulk impedance measurements follow Randles behavior; conduction in the bulk epoxy is ionic, and is diffusion controlled at low frequencies. An additional conduction process between interfacial electrodes is observed even though a water layer does not condense in the interface. Through comparative use of linear network models, it is found that the ``interfacial'' conduction path represents distributed bulk conduction in the epoxy with displacement current leakage into the conductive silicon substrate through an interfacial capacitance. Both electrochemical and bulk coating properties jump at humidities near 70%, indicating greatly increased ionic mobility, coating permittivity, and interfacial capacitances. The permittivity and ionic mobility behavior suggest the formation of large water-swollen demains or highly elongated water clusters near the property jump threshold. Because humidity effects are resolved into bulk and interfacial components, interfacial impedance measurements appear to have great utility for the in situ study of transport and electrochemical properties of interfaces and coatings during environmental exposure.

  2. Polycrystalline silicon ring resonator photodiodes in a bulk complementary metal-oxide-semiconductor process.

    PubMed

    Mehta, Karan K; Orcutt, Jason S; Shainline, Jeffrey M; Tehar-Zahav, Ofer; Sternberg, Zvi; Meade, Roy; Popovi?, Miloš A; Ram, Rajeev J

    2014-02-15

    We present measurements on resonant photodetectors utilizing sub-bandgap absorption in polycrystalline silicon ring resonators, in which light is localized in the intrinsic region of a p+/p/i/n/n+ diode. The devices, operating both at ?=1280 and ?=1550??nm and fabricated in a complementary metal-oxide-semiconductor (CMOS) dynamic random-access memory emulation process, exhibit detection quantum efficiencies around 20% and few-gigahertz response bandwidths. We observe this performance at low reverse biases in the range of a few volts and in devices with dark currents below 50 pA at 10 V. These results demonstrate that such photodetector behavior, previously reported by Preston et al. [Opt. Lett. 36, 52 (2011)], is achievable in bulk CMOS processes, with significant improvements with respect to the previous work in quantum efficiency, dark current, linearity, bandwidth, and operating bias due to additional midlevel doping implants and different material deposition. The present work thus offers a robust realization of a fully CMOS-fabricated all-silicon photodetector functional across a wide wavelength range. PMID:24562278

  3. Light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst

    PubMed Central

    Pijpers, Joep J. H.; Winkler, Mark T.; Surendranath, Yogesh; Buonassisi, Tonio; Nocera, Daniel G.

    2011-01-01

    Integrating a silicon solar cell with a recently developed cobalt-based water-splitting catalyst (Co-Pi) yields a robust, monolithic, photo-assisted anode for the solar fuels process of water splitting to O2 at neutral pH. Deposition of the Co-Pi catalyst on the Indium Tin Oxide (ITO)-passivated p-side of a np-Si junction enables the majority of the voltage generated by the solar cell to be utilized for driving the water-splitting reaction. Operation under neutral pH conditions fosters enhanced stability of the anode as compared to operation under alkaline conditions (pH 14) for which long-term stability is much more problematic. This demonstration of a simple, robust construct for photo-assisted water splitting is an important step towards the development of inexpensive direct solar-to-fuel energy conversion technologies. PMID:21646536

  4. Photoassisted electron emission from metal-oxide-semiconductor cathodes based on nanocrystalline silicon

    NASA Astrophysics Data System (ADS)

    Shimawaki, H.; Neo, Y.; Mimura, H.; Wakaya, F.; Takai, M.

    2013-04-01

    This paper investigates the effect of optical pulses on the electron emission properties of metal-oxide-semiconductor (MOS) cathodes based on nanocrystalline silicon (nc-Si). The emission current is enhanced by about two orders of magnitude by the irradiation of 405 nm laser light. The increase of the emission current under irradiation was proportional to incident laser power. The differential quantum efficiency of the nc-Si based MOS diode itself was estimated to be 3 × 10-2. However, the value of the photoemission current was only 3 × 10-7 due to the short mean free path of hot electron for Pt used as the gate electrode. We obtained a pulsed electron beam from the cathode device by a pulsed laser. The result shows that MOS type cathodes have a suitable structure for optically generating a train of short electron bunches.

  5. Silicon oxide nano-particles doped PQ-PMMA for volume holographic imaging filters

    PubMed Central

    Luo, Yuan; Russo, Juan M.; Kostuk, Raymond K.; Barbastathis, George

    2011-01-01

    Holographic imaging filters are required to have high Bragg selectivity to obtain spatial-spectral information within a three-dimensional object. In this Letter, we present the design of holographic imaging filters formed using silicon oxide nano-particles (nano-SiO2) in PQ-PMMA polymer recording material. This combination offers greater angular and spectral selectivity and increases the diffraction efficiency of holographic filters. The holographic filters with optimized ratio of nano-SiO2 in PQ-PMMA can significantly improve the performance of Bragg selectivity and diffraction efficiency by 53% and 16%, respectively. We present experimental results and data analysis demonstrating this technique in use for holographic spatial-spectral imaging filters. PMID:20410989

  6. The formation of light emitting cerium silicates in cerium-doped silicon oxides

    SciTech Connect

    Li Jing; Zalloum, Othman; Roschuk, Tyler; Heng Chenglin; Wojcik, Jacek; Mascher, Peter [Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4K1 (Canada)

    2009-01-05

    Cerium-doped silicon oxides with cerium concentrations of up to 0.9 at. % were deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition. Bright cerium related photoluminescence, easily seen even under room lighting conditions, was observed from the films and found to be sensitive to film composition and annealing temperature. The film containing 0.9 at. % Ce subjected to anneal in N{sub 2} at 1200 deg. C for 3 h showed the most intense cerium-related emission, easily visible under bright room lighting conditions. This is attributed to the formation of cerium silicate [Ce{sub 2}Si{sub 2}O{sub 7} or Ce{sub 4.667} (SiO{sub 4}){sub 3}O], the presence of which was confirmed by high resolution transmission electron microscopy.

  7. Quantum dot made in metal oxide silicon-nanowire field effect transistor working at room temperature.

    PubMed

    Lavieville, Romain; Triozon, François; Barraud, Sylvain; Corna, Andrea; Jehl, Xavier; Sanquer, Marc; Li, Jing; Abisset, Antoine; Duchemin, Ivan; Niquet, Yann-Michel

    2015-05-13

    We report the observation of an atomic like behavior from T = 4.2 K up to room temperature in n- and p-type ?-gate silicon nanowire (NW) transistors. For that purpose, we modified the design of a NW transistor and introduced long spacers between the source/drain and the channel in order to separate the channel from the electrodes. The channel was made extremely small (3.4 nm in diameter with 10 nm gate length) with a thick gate oxide (7 nm) in order to enhance the Coulomb repulsion between carriers, which can be as large as 200 meV when surface roughness promotes charge confinement. Parasitic stochastic Coulomb blockade effect can be eliminated in our devices by choosing proper control voltages. Moreover, the quantum dot can be tuned so that the resonant current at T = 4.2 K exceeds that at room temperature. PMID:25923197

  8. Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium

    PubMed Central

    Bowers, Carleen M.; Toone, Eric J.; Clark, Robert L.; Shestopalov, Alexander A.

    2011-01-01

    The development of hybrid electronic devices relies in large part on the integration of (bio)organic materials and inorganic semiconductors through a stable interface that permits efficient electron transport and protects underlying substrates from oxidative degradation. Group IV semiconductors can be effectively protected with highly-ordered self-assembled monolayers (SAMs) composed of simple alkyl chains that act as impervious barriers to both organic and aqueous solutions. Simple alkyl SAMs, however, are inert and not amenable to traditional patterning techniques. The motivation for immobilizing organic molecular systems on semiconductors is to impart new functionality to the surface that can provide optical, electronic, and mechanical function, as well as chemical and biological activity. Microcontact printing (?CP) is a soft-lithographic technique for patterning SAMs on myriad surfaces.1-9 Despite its simplicity and versatility, the approach has been largely limited to noble metal surfaces and has not been well developed for pattern transfer to technologically important substrates such as oxide-free silicon and germanium. Furthermore, because this technique relies on the ink diffusion to transfer pattern from the elastomer to substrate, the resolution of such traditional printing is essentially limited to near 1 ?m.10-16 In contrast to traditional printing, inkless ?CP patterning relies on a specific reaction between a surface-immobilized substrate and a stamp-bound catalyst. Because the technique does not rely on diffusive SAM formation, it significantly expands the diversity of patternable surfaces. In addition, the inkless technique obviates the feature size limitations imposed by molecular diffusion, facilitating replication of very small (<200 nm) features.17-23 However, up till now, inkless ?CP has been mainly used for patterning relatively disordered molecular systems, which do not protect underlying surfaces from degradation. Here, we report a simple, reliable high-throughput method for patterning passivated silicon and germanium with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The technique utilizes a preformed NHS-reactive bilayered system on oxide-free silicon and germanium. The NHS moiety is hydrolyzed in a pattern-specific manner with a sulfonic acid-modified acrylate stamp to produce chemically distinct patterns of NHS-activated and free carboxylic acids. A significant limitation to the resolution of many ?CP techniques is the use of PDMS material which lacks the mechanical rigidity necessary for high fidelity transfer. To alleviate this limitation we utilized a polyurethane acrylate polymer, a relatively rigid material that can be easily functionalized with different organic moieties. Our patterning approach completely protects both silicon and germanium from chemical oxidation, provides precise control over the shape and size of the patterned features, and gives ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules. The approach is general and applicable to other technologically-relevant surfaces. PMID:22214997

  9. Soft lithographic functionalization and patterning oxide-free silicon and germanium.

    PubMed

    Bowers, Carleen M; Toone, Eric J; Clark, Robert L; Shestopalov, Alexander A

    2011-01-01

    The development of hybrid electronic devices relies in large part on the integration of (bio)organic materials and inorganic semiconductors through a stable interface that permits efficient electron transport and protects underlying substrates from oxidative degradation. Group IV semiconductors can be effectively protected with highly-ordered self-assembled monolayers (SAMs) composed of simple alkyl chains that act as impervious barriers to both organic and aqueous solutions. Simple alkyl SAMs, however, are inert and not amenable to traditional patterning techniques. The motivation for immobilizing organic molecular systems on semiconductors is to impart new functionality to the surface that can provide optical, electronic, and mechanical function, as well as chemical and biological activity. Microcontact printing (?CP) is a soft-lithographic technique for patterning SAMs on myriad surfaces. Despite its simplicity and versatility, the approach has been largely limited to noble metal surfaces and has not been well developed for pattern transfer to technologically important substrates such as oxide-free silicon and germanium. Furthermore, because this technique relies on the ink diffusion to transfer pattern from the elastomer to substrate, the resolution of such traditional printing is essentially limited to near 1 ?m. In contrast to traditional printing, inkless ?CP patterning relies on a specific reaction between a surface-immobilized substrate and a stamp-bound catalyst. Because the technique does not rely on diffusive SAM formation, it significantly expands the diversity of patternable surfaces. In addition, the inkless technique obviates the feature size limitations imposed by molecular diffusion, facilitating replication of very small (<200 nm) features. However, up till now, inkless ?CP has been mainly used for patterning relatively disordered molecular systems, which do not protect underlying surfaces from degradation. Here, we report a simple, reliable high-throughput method for patterning passivated silicon and germanium with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The technique utilizes a preformed NHS-reactive bilayered system on oxide-free silicon and germanium. The NHS moiety is hydrolyzed in a pattern-specific manner with a sulfonic acid-modified acrylate stamp to produce chemically distinct patterns of NHS-activated and free carboxylic acids. A significant limitation to the resolution of many ?CP techniques is the use of PDMS material which lacks the mechanical rigidity necessary for high fidelity transfer. To alleviate this limitation we utilized a polyurethane acrylate polymer, a relatively rigid material that can be easily functionalized with different organic moieties. Our patterning approach completely protects both silicon and germanium from chemical oxidation, provides precise control over the shape and size of the patterned features, and gives ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules. The approach is general and applicable to other technologically-relevant surfaces. PMID:22214997

  10. Paralinear Oxidation of Silicon Nitride in a Water Vapor/Oxygen Environment

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.; Opila, Elizabeth J.; Nguyen, QuynhGiao; Humphrey, Donald L.; Lewton, Susan M.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Three silicon nitride materials were exposed to dry oxygen flowing at 0.44 cm/s at temperatures between 1200 and 1400 C. Reaction kinetics were measured with a continuously recording microbalance. Parabolic kinetics were observed. When the same materials were exposed to a 50% H2O - 50% O2 gas mixture flowing at 4.4 cm/s, all three types exhibited paralinear kinetics. The material is oxidized by water vapor to form solid silica. The protective silica is in turn volatilized by water vapor to form primarily gaseous Si(OH)4. Nonlinear least squares analysis and a paralinear kinetic model were used to determine both parabolic and linear rate constants from the kinetic data. Volatilization of the protective silica scale can result in accelerated consumption of Si3N4. Recession rates under conditions more representative of actual combustors are compared to the furnace data.

  11. The location and doping effect of boron in Si nanocrystals embedded silicon oxide film

    SciTech Connect

    Xie, Min; Li, Dongsheng; Chen, Le; Wang, Feng; Zhu, Xiaodong; Yang, Deren [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)] [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2013-03-25

    Electrically activated doping of boron (B) atoms into the Si-nanocrystals (Si-NCs) embedded silicon oxide film is achieved by co-sputtering technique following with the annealing treatment. The evolution of the size, the shape, and the density of Si-NCs with the doping of B atoms is investigated. The observation of x-ray photoelectron spectroscopy of Si 2p and B 1s and the decrease in lattice spacing of Si (111) plane suggest that B atoms are doped into Si-NCs. The activated doping is confirmed by the Fano effect of the micro-Raman spectra for Si-NCs and the drastic decrease of the sheet resistance.

  12. Inductively heated synthesized graphene with record transistor mobility on oxidized silicon substrates at room temperature

    NASA Astrophysics Data System (ADS)

    Tao, Li; Lee, Jongho; Li, Huifeng; Piner, Richard D.; Ruoff, Rodney S.; Akinwande, Deji

    2013-10-01

    We report chemical vapor-deposited (CVD) graphene field-effect transistors (GFETs) on conventional SiO2/Si substrate with high-performance comparable to GFETs on boron nitride under practical ambient conditions. The fabricated GFET statistics reveal maximum carrier mobility of ˜17 800 cm2/V-s. Intrinsic graphene features such as three-region output characteristics including soft current saturation have also been observed, in addition to over ten-fold gate modulation. Low-temperature studies indicate that impurity scattering is the limiting transport mechanism. Our results on graphene, synthesized by an inductively heated CVD system, suggest that the prospects of GFETs on oxidized silicon are comparable to those on ideal surfaces, e.g., hBN at room temperature.

  13. Fabrication and properties of microporous silicon 

    E-print Network

    Shao, Jianzhong

    1994-01-01

    structure as the wafer from which it was fabricated. Oxidization at 800'C converts the porous silicon totally to amorphous silicon dioxide. Oxidation at 600'C produces a mixture of crystalline silicon and amorphous silicon dioxide. The pore structure...

  14. The n-silicon/thallium(III) oxide heterojunction photoelectrochemical solar cell

    SciTech Connect

    Switzer, J.A.

    1986-04-01

    Thallium(III) oxide is a degenerate n-type semiconductor which can be electrochemically or photoelectrochemically deposited on conducting or semiconducting substrates. The material is highly conductive, transparent, and electrocatalytic. A photoelectrochemical cell consisting of the n-silicon/thallium(III) oxide photoanode and a platinum cathode in an alkaline solution of the ferrocyanide/ferricyanide redox couple produced a 0.512V open-circuit photovoltage, 33.5 mA/cm/sup 2/ short-circuit photocurrent density, 0.643 fill factor, and 13.8, photovoltaic efficiency with 80 mW/cm/sup 2/ iR-filtered xenon light. The efficiency was 11.0% with 75.3 mW/cm/sup 2/ natural sunlight, and 22.3% with 800 nm monochromatic light. The short-circuit quantum efficiency at 800 nm was 97%. A xenon photovoltaic efficiency of 10.2% was observed with cast multicrystalline n-silicon. Photocurrent-voltage curves were computer simulated using values of the barrier height (0.96V), diode quality factor (1.2), and series resistance (200..cap omega..) that were measured from dark current voltage and capacitance-voltage curves. A solid-state photovoltaic cell was fabricated by making a low-pressure point contact to the front surface of a dry photoanode. The photovoltaic characteristics of the solid-state cell were nearly identical with those of the photoelectrochemical cell. These results suggest that the photoelectrochemical cell functions like a Schottky-barrier or SIS solid-state photovoltaic cell in series with a highly reversible electrochemical cell.

  15. Bismuth Passivation Technique for High-Resolution X-Ray Detectors

    NASA Technical Reports Server (NTRS)

    Chervenak, James; Hess, Larry

    2013-01-01

    The Athena-plus team requires X-ray sensors with energy resolution of better than one part in 3,000 at 6 keV X-rays. While bismuth is an excellent material for high X-ray stopping power and low heat capacity (for large signal when an X-ray is stopped by the absorber), oxidation of the bismuth surface can lead to electron traps and other effects that degrade the energy resolution. Bismuth oxide reduction and nitride passivation techniques analogous to those used in indium passivation are being applied in a new technique. The technique will enable improved energy resolution and resistance to aging in bismuth-absorber-coupled X-ray sensors. Elemental bismuth is lithographically integrated into X-ray detector circuits. It encounters several steps where the Bi oxidizes. The technology discussed here will remove oxide from the surface of the Bi and replace it with nitridized surface. Removal of the native oxide and passivating to prevent the growth of the oxide will improve detector performance and insulate the detector against future degradation from oxide growth. Placing the Bi coated sensor in a vacuum system, a reduction chemistry in a plasma (nitrogen/hydrogen (N2/H2) + argon) is used to remove the oxide and promote nitridization of the cleaned Bi surface. Once passivated, the Bi will perform as a better X-ray thermalizer since energy will not be trapped in the bismuth oxides on the surface. A simple additional step, which can be added at various stages of the current fabrication process, can then be applied to encapsulate the Bi film. After plasma passivation, the Bi can be capped with a non-diffusive layer of metal or dielectric. A non-superconducting layer is required such as tungsten or tungsten nitride (WNx).

  16. Low temperature direct bonding mechanisms of tetraethyl orthosilicate based silicon oxide films deposited by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Sabbione, C.; Di Cioccio, L.; Vandroux, L.; Nieto, J.-P.; Rieutord, F.

    2012-09-01

    Bonding behaviour and surface adhesion mechanisms of tetraethyl orthosilicate silicon oxide films are investigated. Prior to the bonding, infrared absorption spectroscopy was used to assess chemical composition of the bonding layers. The incorporation of -OH groups during the deposition process and the moisture absorption is shown and a specific effect of the applied RF power is highlighted. A strong correlation is found between trapped species and the evolution of the bonded layers during subsequent thermal annealing. The first observed phenomenon is an overall hardness reduction of the film deposited at low RF power which results in an increase of local adhesion area, hence an enhancement of the bonding energy. In the meantime, in this configuration water production is promoted in the volume of the film through silanol condensation and silicon oxidation occurs at the interface between the bonding layer and the silicon bulk. As a by-product of this reaction, hydrogen is released and it migrates towards the bonding interface. As a consequence, defects appear at the bonding interface. Thanks to the use of a stop barrier at the bulk interface, silicon oxidation is prevented, defect free bonding is obtained and the described scenario is confirmed.

  17. 21 CFR 73.2110 - Bismuth citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. ...bismuth citrate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of bismuth citrate in the cosmetic shall not be in excess of 0.5...

  18. 21 CFR 73.2110 - Bismuth citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. ...bismuth citrate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of bismuth citrate in the cosmetic shall not be in excess of 2.0...

  19. Nano sized bismuth oxy chloride by metal organic chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Jagdale, Pravin; Castellino, Micaela; Marrec, Françoise; Rodil, Sandra E.; Tagliaferro, Alberto

    2014-06-01

    Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl3) in acetone (CH3sbnd COsbnd CH3). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18-250 nm thick and a few micrometres wide.

  20. Stress control of plasma enhanced chemical vapor deposited silicon oxide film from tetraethoxysilane

    NASA Astrophysics Data System (ADS)

    Guan, D.; Bruccoleri, A. R.; Heilmann, R. K.; Schattenburg, M. L.

    2014-02-01

    Thin silicon dioxide films have been studied as a function of deposition parameters and annealing temperatures. Films were deposited by tetraethoxysilane (TEOS) dual-frequency plasma enhanced chemical vapor deposition with different time interval fractions of high-frequency and low-frequency plasma depositions. The samples were subsequently annealed up to 930 °C to investigate their stress behavior. Films that were deposited in high-frequency dominated plasma were found to have tensile residual stress after annealing at temperatures higher than 800 °C. The residual stress can be controlled to slightly tensile by changing the annealing temperature. High tensile stress was observed during the annealing of high-frequency plasma-deposited films, leading to film cracks that limit the film thickness, as predicted by the strain energy release rate equation. Thick films without cracks were obtained by iterating deposition and annealing to stack multiple layers. A series of wet cleaning experiments were conducted, and we discovered that water absorption in high-frequency plasma-deposited films causes the residual stress to decrease. A ?40 nm thick low-frequency deposited oxide cap is sufficient to prevent water from diffusing through the film. Large-area free-standing tensile stressed oxide membranes without risk of buckling were successfully fabricated.

  1. Continuous-flow Mass Production of Silicon Nanowires via Substrate-Enhanced Metal-Catalyzed Electroless Etching of Silicon with Dissolved Oxygen as an Oxidant

    NASA Astrophysics Data System (ADS)

    Hu, Ya; Peng, Kui-Qing; Liu, Lin; Qiao, Zhen; Huang, Xing; Wu, Xiao-Ling; Meng, Xiang-Min; Lee, Shuit-Tong

    2014-01-01

    Silicon nanowires (SiNWs) are attracting growing interest due to their unique properties and promising applications in photovoltaic devices, thermoelectric devices, lithium-ion batteries, and biotechnology. Low-cost mass production of SiNWs is essential for SiNWs-based nanotechnology commercialization. However, economic, controlled large-scale production of SiNWs remains challenging and rarely attainable. Here, we demonstrate a facile strategy capable of low-cost, continuous-flow mass production of SiNWs on an industrial scale. The strategy relies on substrate-enhanced metal-catalyzed electroless etching (MCEE) of silicon using dissolved oxygen in aqueous hydrofluoric acid (HF) solution as an oxidant. The distinct advantages of this novel MCEE approach, such as simplicity, scalability and flexibility, make it an attractive alternative to conventional MCEE methods.

  2. The silicon/zinc oxide interface in amorphous silicon-based thin-film solar cells: Understanding an empirically optimized contact

    NASA Astrophysics Data System (ADS)

    Gerlach, D.; Wilks, R. G.; Wippler, D.; Wimmer, M.; Lozac'h, M.; Félix, R.; Mück, A.; Meier, M.; Ueda, S.; Yoshikawa, H.; Gorgoi, M.; Lips, K.; Rech, B.; Sumiya, M.; Hüpkes, J.; Kobayashi, K.; Bär, M.

    2013-07-01

    The electronic structure of the interface between the boron-doped oxygenated amorphous silicon "window layer" (a-SiOx:H(B)) and aluminum-doped zinc oxide (ZnO:Al) was investigated using hard x-ray photoelectron spectroscopy and compared to that of the boron-doped microcrystalline silicon (?c-Si:H(B))/ZnO:Al interface. The corresponding valence band offsets have been determined to be (-2.87 ± 0.27) eV and (-3.37 ± 0.27) eV, respectively. A lower tunnel junction barrier height at the ?c-Si:H(B)/ZnO:Al interface compared to that at the a-SiOx:H(B)/ZnO:Al interface is found and linked to the higher device performances in cells where a ?c-Si:H(B) buffer between the a-Si:H p-i-n absorber stack and the ZnO:Al contact is employed.

  3. Continuous-flow mass production of silicon nanowires via substrate-enhanced metal-catalyzed electroless etching of silicon with dissolved oxygen as an oxidant.

    PubMed

    Hu, Ya; Peng, Kui-Qing; Liu, Lin; Qiao, Zhen; Huang, Xing; Wu, Xiao-Ling; Meng, Xiang-Min; Lee, Shuit-Tong

    2014-01-01

    Silicon nanowires (SiNWs) are attracting growing interest due to their unique properties and promising applications in photovoltaic devices, thermoelectric devices, lithium-ion batteries, and biotechnology. Low-cost mass production of SiNWs is essential for SiNWs-based nanotechnology commercialization. However, economic, controlled large-scale production of SiNWs remains challenging and rarely attainable. Here, we demonstrate a facile strategy capable of low-cost, continuous-flow mass production of SiNWs on an industrial scale. The strategy relies on substrate-enhanced metal-catalyzed electroless etching (MCEE) of silicon using dissolved oxygen in aqueous hydrofluoric acid (HF) solution as an oxidant. The distinct advantages of this novel MCEE approach, such as simplicity, scalability and flexibility, make it an attractive alternative to conventional MCEE methods. PMID:24413157

  4. FABRICATION OF BISMUTH NANOWIRE DEVICES USING FOCUSED ION BEAM MILLING

    SciTech Connect

    Cheng, H. H. [Centre for Microscopy and Microanalysis, Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Queensland 4072 (Australia); Alkaisi, M. M. [MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140 (New Zealand); Wu, S. E.; Liu, C. P. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2009-07-23

    In this work, a focused ion beam (FIB) milling process has been developed to fabricate 50 nm Bi nanowire and transistor structures using FEI-200 dual beam FIB system. For the fabrication, 50 nm bismuth film was thermally evaporated through EBL patterned PMMA windows onto SiO{sub 2} substrates with pre-defined contact pads. Bi nanowire widths ranging from 30 nm to 100 nm have been successfully fabricated by milling out unwanted areas using 30 KeV Ga+ ion beam. A single-pixel-line ion beam blanking technique has been utilised to fabricate Bi nanowire as small as 30 nm in diameter and few micrometers long. In order to form good ohmic contacts for sub 50 nm bismuth nanowires, a drill-and-fill process has been developed using FIB to sputter away the surface oxide of bismuth after the in-situ platinum nanowire contacts deposition. To our knowledge, this is the first time a focused ion beam process has been used to fabricate bismuth nanowire. The fabricated Bi nanowires were electrically characterised using a semiconductor analyser that showed good ohmic contact to the electrodes. In this paper, the fabrication experiments and the characterisation results for Bi nanowires as small as 50 nm in diameter are presented. Several FIB issues involved in Bi device making and ohmic contacts to Bi nanowires will also be discussed.

  5. Third order nonlinear optical properties of bismuth zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V.; Kuladeep, R.; Narayana Rao, D.

    2013-12-01

    Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi2O3-30ZnO-(70-x) B2O3 (where x = 30, 35, 40, and 45 mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (?) and the absorption cross section due to free carriers (?e) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

  6. Third order nonlinear optical properties of bismuth zinc borate glasses

    SciTech Connect

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V., E-mail: ravi.phy@pondiuni.edu.in [Department of Physics, Pondicherry University, Puducherry 605 014 (India); Kuladeep, R.; Narayana Rao, D. [School of Physics, University of Hyderabad, Hyderabad 500046, Andhra Pradesh (India)

    2013-12-28

    Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi{sub 2}O{sub 3}-30ZnO-(70-x) B{sub 2}O{sub 3} (where x?=?30, 35, 40, and 45?mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (?) and the absorption cross section due to free carriers (?{sub e}) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

  7. [Synergetic effects of silicon carbide and molecular sieve loaded catalyst on microwave assisted catalytic oxidation of toluene].

    PubMed

    Wang, Xiao-Hui; Bo, Long-Li; Liu, Hai-Nan; Zhang, Hao; Sun, Jian-Yu; Yang, Li; Cai, Li-Dong

    2013-06-01

    Molecular sieve loaded catalyst was prepared by impregnation method, microwave-absorbing material silicon carbide and the catalyst were investigated for catalytic oxidation of toluene by microwave irradiation. Research work examined effects of silicon carbide and molecular sieve loading Cu-V catalyst's mixture ratio as well as mixed approach changes on degradation of toluene, and characteristics of catalyst were measured through scanning electron microscope, specific surface area test and X-ray diffraction analysis. The result showed that the fixed bed reactor had advantages of both thermal storage property and low-temperature catalytic oxidation when 20% silicon carbide was filled at the bottom of the reactor, and this could effectively improve the utilization of microwave energy as well as catalytic oxidation efficiency of toluene. Under microwave power of 75 W and 47 W, complete-combustion temperatures of molecular sieve loaded Cu-V catalyst and Cu-V-Ce catalyst to toluene were 325 degrees C and 160 degrees C, respectively. Characteristics of the catalysts showed that mixture of rare-earth element Ce increased the dispersion of active components in the surface of catalyst, micropore structure of catalyst effectively guaranteed high adsorption capacity for toluene, while amorphous phase of Cu and V oxides increased the activity of catalyst greatly. PMID:23947020

  8. 5H-1 Effects of Fine Metal Oxide Particle Dopant on the Acoustic Properties of Silicone Rubber Lens for Medical Array Probe

    Microsoft Academic Search

    Yasuharu Hosono; Yohachi Yamashita; Kazuhiro Itsumi

    2006-01-01

    The effects of fine metal oxide particles, particularly those of high density elements (7.7 to 9.7 times 103 kg\\/m3), on the acoustic properties of silicone rubber have been investigated, in order to develop an acoustic lens with a low acoustic attenuation. Silicone rubber doped with Yb2O3 powder having nanoparticle size of 16 nm showed a lower acoustic attenuation than silicone

  9. Trap Concentration Dependence on the Electrical Properties of Annealed Ultrathin Fluorinated Silicon Oxides

    NASA Astrophysics Data System (ADS)

    Chang, Wai-Jyh; Houng, Mau-Phon; Wang, Yeong-Her

    2001-03-01

    In this study, the electrical properties of ultrathin (5-9 nm) liquid-phase-deposited fluorinated silicon oxides (LPD-SiOFs) are investigated under various annealing conditions. The electron tunneling current at Eox=4--6 MV/cm is suggested to be modeled by a generalized trap-assisted tunneling (GTAT) mechanism with consideration of trapezoidal- and triangular-barrier tunnelings. This gives the trap concentration (Nt) and the trap energy level (?t) of a trapped oxide that is induced by fluorine incorporation. The reported ?t of fluorine is around 1.98-2.2 eV while Nt for O2-annealed LPD-SiOF is 1× 1016--3× 1018 cm-3 and Nt for N2O-annealed LPD-SiOF is 5× 1014--2× 1015 cm-3, depending on the annealing conditions. The trap concentration within the LPD-SiOF film is demonstrated to decrease with an increase in annealing temperature and time. From the GTAT modeling of O2- and N2O-annealed LPD-SiOF films, it is obvious that nitridation in N2O can substantially reduce the concentration of traps (by an order of magnitude of two) contained in original LPD-SiOF films. The flat-band voltage shift, interface trap density, constant current stress (CCS), and constant voltage stress (CVS) all show that LPD-SiOF annealed in N2O has the best material quality in comparison with others. As shown in the experimental and modeling results, the traps are found to be strongly dependent on the impurities contained in the oxide films (F or N atoms in this study). Using the GTAT model, we can derive the trap energy level and trap concentration simply from the current-voltage (I-V) characteristics without the use of other complicated measuring techniques.

  10. Elementary reaction schemes for physical and chemical vapor deposition of transition metal oxides on silicon for high-k gate dielectric applications

    Microsoft Academic Search

    D. Niu; R. W. Ashcraft; M. J. Kelly; J. J. Chambers; T. M. Klein; G. N. Parsons

    2002-01-01

    This article describes the kinetics of reactions that result in substrate consumption during formation of ultrathin transition metal oxides on silicon. Yttrium silicate films (~40 Å) with an equivalent silicon dioxide thickness of ~11 Å are demonstrated by physical vapor deposition (PVD) routes. Interface reactions that occur during deposition and during postdeposition treatment are observed and compared for PVD and

  11. Total Platinum Concentration and Platinum Oxidation States in Body Fluids, Tissue, and Explants from Women Exposed to Silicone and Saline Breast Implants by IC?ICPMS

    Microsoft Academic Search

    E. D. Lykissa; S. V. M. Maharaj

    2006-01-01

    Ion chromatography-inductively coupled plasma-mass spectrometry was used to determine the total platinum concentration and platinum oxidation states in samples from women exposed to silicone and saline breast im- plants. Samples included the following: whole blood, urine, hair, nails, sweat, brain tissue, breast milk, and explants. Mean Pt concentration in samples from women exposed to silicone breast implants were as follows:

  12. Optical and electrical investigations of poly( p-phenylene vinylene)\\/silicon oxide and poly( p-phenylene vinylene)\\/titanium oxide nanocomposites

    Microsoft Academic Search

    S. H. Yang; T. P. Nguyen; P. Le Rendu; C. S. Hsu

    2005-01-01

    Composites made by incorporation of silicon oxide (SiO2) or titanium (TiO2) nanoparticles into poly(p-phenylene vinylene) (PPV) have been fabricated and their electrical and optical properties have been investigated. The UV-vis absorption and Raman spectra showed that SiO2 nanoparticles reduced the conjugation lengths of PPV chains, while TiO2 nanoparticles did not. In the case of SiO2 nanoparticles, the reduction of conjugation

  13. Role of surface oxides in the formation of solid-electrolyte interphases at silicon electrodes for lithium-ion batteries.

    PubMed

    Schroder, Kjell W; Dylla, Anthony G; Harris, Stephen J; Webb, Lauren J; Stevenson, Keith J

    2014-12-10

    Nonaqueous solvents in modern battery technologies undergo electroreduction at negative electrodes, leading to the formation of a solid-electrolyte interphase (SEI). The mechanisms and reactions leading to a stable SEI on silicon electrodes in lithium-ion batteries are still poorly understood. This lack of understanding inhibits the rational design of electrolyte additives, active material coatings, and the prediction of Li-ion battery life in general. We prepared SEI with a common nonaqueous solvent (LiPF6 in PC and in EC/DEC 1:1 by wt %) on silicon oxide and etched silicon (001) surfaces in various states of lithiation to understand the role of surface chemistry on the SEI formation mechanism and SEI structure. Anhydrous and anoxic techniques were used to prevent air and moisture contamination of prepared SEI films, allowing for more accurate characterization of SEI chemical stratification and composition by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) depth profiling. Additionally, multivariate statistical methods were used to better understand TOF-SIMS depth profiling studies. We conclude that the absence of native-oxide layer on silicon has a significant impact on the formation, composition, structure, and thickness of the SEI. PMID:25402271

  14. Porous silicon carbide and aluminum oxide with unidirectional open porosity as model target materials for radioisotope beam production

    NASA Astrophysics Data System (ADS)

    Czapski, M.; Stora, T.; Tardivat, C.; Deville, S.; Santos Augusto, R.; Leloup, J.; Bouville, F.; Fernandes Luis, R.

    2013-12-01

    New silicon carbide (SiC) and aluminum oxide (Al2O3) of a tailor-made microstructure were produced using the ice-templating technique, which permits controlled pore formation conditions within the material. These prototypes will serve to verify aging of the new advanced target materials under irradiation with proton beams. Before this, the evaluation of their mechanical integrity was made based on the energy deposition spectra produced by FLUKA codes.

  15. Mechanism of Potential Profile Formation in Silicon Single-Electron Transistors Fabricated Using Pattern-Dependent Oxidation

    Microsoft Academic Search

    Seiji Horiguchi; Masao Nagase; Kenji Shiraishi; Hiroyuki Kageshima; Yasuo Takahashi; Katsumi Murase

    2001-01-01

    The origin of the potential profile in silicon single-electron transistors (SETs) fabricated using pattern-dependent oxidation (PADOX) is investigated by making use of the geometric structure measured by atomic force microscope (AFM), the bandgap reduction due to compressive stress generated during PADOX obtained using the first-principles calculation, and the effective potential method. A probable mechanism for the formation of the potential

  16. Effect of Dual-Function Nano-Structured Silicon Oxide Thin Film on Multi-Junction Solar Cells

    Microsoft Academic Search

    B. Yan; L. Sivec; G. Yue; C. S. Jiang; J. Yang; S. Guha

    2011-01-01

    We present our recent study of using nano-structured hydrogenated silicon oxide films (nc-SiOâ:H) as a dual-function layer in multi-junction solar cells. The nc-SiOâ:H films were deposited using very high frequency glow discharge of a SiHâ (or SiâHâ), COâ, PHâ, and Hâ gas mixture. By optimizing deposition parameters, we obtained 'dual function' nc-SiOâ:H material characterized by a conductivity suitable for use

  17. Effect of dual-function nano-structured silicon oxide thin film on multi-junction solar cells

    Microsoft Academic Search

    Baojie Yan; Laura Sivec; Guozhen Yue; Chun-Sheng Jiang; Jeffrey Yang; Subhendu Guha

    2011-01-01

    We present our recent study of using nano-structured hydrogenated silicon oxide films (nc-SiOx:H) as a dual-function layer in multi-junction solar cells. The nc-SiOx:H films were deposited using very high frequency glow discharge of a SiH4 (or Si2H6), CO2, PH3, and H2 gas mixture. By optimizing deposition parameters, we obtained \\

  18. Mechanical properties of carbon-modified silicon oxide barrier films deposited by plasma enhanced chemical vapor deposition on polymer substrates

    Microsoft Academic Search

    A. Bieder; V. Gondoin; Y. Leterrier; G. Tornare; Ph. Rudolf von Rohr; J.-A. E. Månson

    2007-01-01

    Cohesive and adhesive properties of silicon oxide barrier coatings deposited from an oxygen\\/hexamethyldisiloxane gas mixture by plasma enhanced chemical vapor deposition, with controlled incorporation of carbon on 12 ?m thick polyethylene terephtalate films were investigated. The reactor was equipped with a 2.45 GHz slot antenna plasma source and a 13.56 MHz-biased substrate holder. The two plasma sources were operated separately or in a

  19. Properties of a Thin-Film Optical Waveguide Using Fluorinated Silicon Oxide and Organic Spin-on-Glass Films

    Microsoft Academic Search

    Tetsuya Homma; Hiroyasu Kondo; Msaya Sakamoto; Masahiro Nomoto; Kazuaki Inohara; Yuji Ariyama; Masahiro Itoh; Hideo Takahashi

    2000-01-01

    A thin-film optical waveguide using a fluorinated silicon oxide (SiOF) as a core layer was investigated. An organic spin-on-glass (SOG) film was used for a cladding layer. The SiOF films were formed at 23°C by a liquid-phase deposition (LPD) technique using a supersaturated hydrofluosilicic acid (H2SiF6) aqueous solution. A thin-film optical waveguide structure for single mode was designed and fabricated,

  20. Evaluation and Resolution for Nonideal Characteristics of Complementary MetalOxideSemiconductor Devices Fabricated on Silicon-on-Insulator

    Microsoft Academic Search

    Seongjae Cho; Il Han Park; Jung Hoon Lee; Jong Duk Lee; Byung-Gook Park

    2008-01-01

    By virtue of inherent advantages including higher controllability of gate over channel electrons, very low junction capacitance, and soft-error immunity of silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistors (MOSFETs), there have been increasing demands for implementation of devices on SOI. Operating the systems constructed on SOI calls for more accurate and tangible understanding of complementary MOS (CMOS) devices on SOI. From

  1. Fabrication of silicon nanowire/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-graphene oxide hybrid solar cells

    NASA Astrophysics Data System (ADS)

    Uma, Kasimayan; Subramani, Thiyagu; Syu, Hong-Jhang; Lin, Tzu-Ching; Lin, Ching-Fuh

    2015-03-01

    Silicon nanowire (SiNW)/Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) Schottky junctions have shown great promise as high efficiency, cost effective solar cells. Here, hybrid SiNWs/PEDOT:PSS blended graphene oxide (GO) solar cells are prepared and investigated. The SiNWs/PEDOT:PSS blended GO cells show enhanced light trapping and a large junction area when compared to pure PEDOT:PSS structures. SiNWs combined with GO solar cells show energy conversion efficiencies of up to 9.57% under the AM 1.5G condition, opening the possibility of using semiconductor/graphene oxide in photovoltaic applications.

  2. Strong anisotropy of ferroelectricity in lead-free bismuth silicate.

    PubMed

    Seol, Daehee; Taniguchi, Hiroki; Hwang, Jae-Yeol; Itoh, Mitsuru; Shin, Hyunjung; Kim, Sung Wng; Kim, Yunseok

    2015-07-21

    Bismuth silicate (Bi2SiO5) was recently suggested as a potential silicate based lead-free ferroelectric material. Here, we show the existence of ferroelectricity and explore the strong anisotropy of local ferroelectricity using piezoresponse force microscopy (PFM). Domain structures are reconstructed using angle-resolved PFM. Furthermore, piezoresponse hysteresis loops and piezoelectric coefficients are spatially investigated at the nanoscale. The obtained results confirm the existence of ferroelectricity with strong c-axis polarization. These results could provide basic information on the anisotropic ferroelectricity in Bi2SiO5 and furthermore suggest its considerable potential for lead-free ferroelectric applications with silicon technologies. PMID:26084633

  3. Effect of ion-irradiation induced defects on the nanocluster Si/Er{sup 3+} coupling in Er-doped silicon-rich silicon oxide

    SciTech Connect

    Seo, Se-Young; Jeong, Hoon; Shin, Jung H.; Choi, Han Woo; Woo, Hyung Joo; Kim, Joon Kon [Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Ion Beam Application Group, Korean Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of)

    2007-07-09

    The effect of ion-irradiation induced defects on the nanocluster Si/Er{sup 3+} coupling in Er-doped silicon-rich silicon oxide (SRSO) thin film is investigated. Er-doped SRSO, which consists of silicon nanoclusters (nc-Si) in a SiO{sub 2} matrix, was fabricated using electron-cyclotron resonance plasma enhanced chemical vapor deposition using SiH{sub 4} and O{sub 2} with concurrent sputtering of Er followed by a high temperature annealing. Defects were introduced into the film via irradiation with 3 MeV Si ions and subsequently removed by high temperature annealings. The authors find that ion irradiation reduces Er{sup 3+} luminescence from SRSO films, even when the excitation cross section and luminescence efficiency of Er{sup 3+} ions are completely restored. On the other hand, ion irradiation increases the intrinsic nc-Si luminescence and has little effect on the Er{sup 3+} luminescence from a similarly prepared, Er-doped SiO{sub 2} film, indicating that the presence of irradiation induced defects in the initial amorphous film can reduce the number of Er{sup 3+} ions available for nc-Si mediated luminescence by as much as a factor of 3.

  4. Low power zinc-oxide based charge trapping memory with embedded silicon nanoparticles via poole-frenkel hole emission

    SciTech Connect

    El-Atab, Nazek; Nayfeh, Ammar [Department of Electrical Engineering and Computer Science (EECS), Institute Center for Microsystems–iMicro, Masdar Institute of Science and Technology, Abu Dhabi (United Arab Emirates)] [Department of Electrical Engineering and Computer Science (EECS), Institute Center for Microsystems–iMicro, Masdar Institute of Science and Technology, Abu Dhabi (United Arab Emirates); Ozcan, Ayse; Alkis, Sabri [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey)] [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Okyay, Ali K. [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey) [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara (Turkey)

    2014-01-06

    A low power zinc-oxide (ZnO) charge trapping memory with embedded silicon (Si) nanoparticles is demonstrated. The charge trapping layer is formed by spin coating 2?nm silicon nanoparticles between Atomic Layer Deposited ZnO steps. The threshold voltage shift (?V{sub t}) vs. programming voltage is studied with and without the silicon nanoparticles. Applying ?1?V for 5?s at the gate of the memory with nanoparticles results in a ?V{sub t} of 3.4?V, and the memory window can be up to 8?V with an excellent retention characteristic (>10 yr). Without nanoparticles, at ?1?V programming voltage, the ?V{sub t} is negligible. In order to get ?V{sub t} of 3.4?V without nanoparticles, programming voltage in excess of 10?V is required. The negative voltage on the gate programs the memory indicating that holes are being trapped in the charge trapping layer. In addition, at 1?V the electric field across the 3.6?nm tunnel oxide is calculated to be 0.36 MV/cm, which is too small for significant tunneling. Moreover, the ?V{sub t} vs. electric field across the tunnel oxide shows square root dependence at low fields (E??2.7 MV/cm). This indicates that Poole-Frenkel Effect is the main mechanism for holes emission at low fields and Phonon Assisted Tunneling at higher fields.

  5. Crystallization of amorphous bismuth titanate

    Microsoft Academic Search

    Seiji Kojima; Anwar Hushur; Fuming Jiang; Sinichi Hamazaki; Masaaki Takashige; Min-Su Jang; Shiro Shimada

    2001-01-01

    We studied the transformation of amorphous bismuth titanate by heat treatments. After an as-quenched amorphous sample was annealed at 500 °C, the lowest Raman peak became intense like a boson peak for glass. This fact indicates the formation of intermediate range order. The medium range correlation length of 7 nm calculated from the boson peak frequency is in agreement with

  6. Structural and photoluminescence properties of ZnO nanoparticles on silicon oxide

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, K.; Boukos, N.; Travlos, A.; Monteiro, T.; Soares, M. J.; Peres, M.; Neves, A.; Carmo, M. C.

    2007-07-01

    Isolated, self assembled ZnO nanoparticles are grown in two steps: by the electron beam evaporation of Zn on oxidised silicon wafers, during which isolated Zn nanodots are grown, and a subsequent annealing in oxygen that results in the desired ZnO nanodots. Low temperature PL measurements of the ZnO nanodots show that the near band edge part of the spectra is dominated by a zero phonon line near 3.36 eV which is an overlap of two emitting lines near 3.363 eV and 3.367 eV. Characterization by TEM and EELS shows that the nanoparticles are zinc oxide single crystals grown with their c-axis perpendicular to the substrate; their distribution, size and crystallinity depend on the deposition parameters of zinc and the growth substrate. We discuss the effect of these parameters on the morphology of the resulting material. Our approach demonstrates a simple method for the growth of high purity isolated ZnO nanodots of similar sizes, distributed uniformly on a large surface.

  7. Performance enhancement of ITO/oxide/semiconductor MOS-structure silicon solar cells with voltage biasing

    NASA Astrophysics Data System (ADS)

    Ho, Wen-Jeng; Huang, Min-Chun; Lee, Yi-Yu; Hou, Zhong-Fu; Liao, Changn-Jyun

    2014-12-01

    In this study, we demonstrate the photovoltaic performance enhancement of a p-n junction silicon solar cell using a transparent-antireflective ITO/oxide film deposited on the spacing of the front-side finger electrodes and with a DC voltage applied on the ITO-electrode. The depletion width of the p-n junction under the ITO-electrode was induced and extended while the absorbed volume and built-in electric field were also increased when the biasing voltage was increased. The photocurrent and conversion efficiency were increased because more photo-carriers are generated in a larger absorbed volume and because the carriers transported and collected more effectively due to higher biasing voltage effects. Compared to a reference solar cell (which was biased at 0 V), a conversion efficiency enhancement of 26.57% (from 12.42% to 15.72%) and short-circuit current density enhancement of 42.43% (from 29.51 to 42.03 mA/cm2) were obtained as the proposed MOS-structure solar cell biased at 2.5 V. In addition, the capacitance-volt (C-V) measurement was also used to examine the mechanism of photovoltaic performance enhancement due to the depletion width being enlarged by applying a DC voltage on an ITO-electrode.

  8. Molecular printboards on silicon oxide: lithographic patterning of cyclodextrin monolayers with multivalent, fluorescent guest molecules.

    PubMed

    Mulder, Alart; Onclin, Steffen; Péter, Mária; Hoogenboom, Jacob P; Beijleveld, Hans; ter Maat, Jurjen; García-Parajó, María F; Ravoo, Bart Jan; Huskens, Jurriaan; van Hulst, Niek F; Reinhoudt, David N

    2005-02-01

    Three compounds bearing multiple adamantyl guest moieties and a fluorescent dye have been synthesized for the supramolecular patterning of beta-cyclodextrin (CD) host monolayers on silicon oxide using microcontact printing and dip-pen nanolithography. Patterns created on monolayers on glass were viewed by laser scanning confocal microscopy. Semi-quantitative analysis of the patterns showed that with microcontact printing approximately a single monolayer of guest molecules is transferred. Exposure to different rinsing procedures showed the stability of the patterns to be governed by specific supramolecular multivalent interactions. Patterns of the guest molecules created at CD monolayers were stable towards thorough rinsing with water, whereas similar patterns created on poly(ethylene glycol) (PEG) reference monolayers were instantly removed. The patterns on CD monolayers displayed long-term stability when stored under N(2), whereas patterns at PEG monolayers faded within a few weeks due to the diffusion of fluorescent molecules across the surface. Assemblies at CD monolayers could be mostly removed by rinsing with a concentrated CD solution, demonstrating the reversibility of the methodology. Patterns consisting of different guest molecules were produced by microcontact printing of one guest molecule and specific adsorption of a second guest molecule from solution to non-contacted areas, giving well-defined alternating assemblies. Fluorescent features of sub-micrometer dimensions were written using supramolecular dip-pen nanolithography. PMID:17193439

  9. Extraordinary elevation of the glass transition temperature of thin polymer films grafted to silicon oxide substrates

    NASA Astrophysics Data System (ADS)

    Tate, Ranjeet S.; Fryer, David S.; Pasqualini, Silvia; Montague, Martha F.; de Pablo, Juan J.; Nealey, Paul F.

    2001-12-01

    We used local thermal analysis and ellipsometry to measure the glass transition temperatures (Tg) of supported thin films of poly(4-hydroxystyrene) (PHS) and hydroxy terminated polystyrene (PS-OH). The films were spuncast from solution onto silicon oxide substrates and annealed under vacuum at elevated temperatures to graft the polymer to the substrate. Grafting was verified and characterized in terms of the thickness of and the advancing contact angle of water on the residual layer after solvent extraction. For PHS, each segment of the polymer chain was capable of grafting to the substrate. The thickness of the residual layer increased with increasing annealing temperature. For this polymer the critical thickness below which the Tg of the film deviated from the bulk value was nearly 200 nm after annealing at the highest temperature (190 °C); the Tg of films 100 nm thick or less were elevated by more than 50 °C above the bulk value. For PS-OH films the polymer was only capable of grafting at one chain end, forming a brush layer at the substrate interface. The critical thicknesses for PS-OH films and the Tg elevations were substantially higher than for ungrafted PS films, but were not as large as for PHS. The film thickness dependence of Tg for PHS and PS-OH were well described as piecewise linear, consistent with a "dual-mechanism" model.

  10. Organic-on-silicon complementary metal-oxide-semiconductor colour image sensors.

    PubMed

    Lim, Seon-Jeong; Leem, Dong-Seok; Park, Kyung-Bae; Kim, Kyu-Sik; Sul, Sangchul; Na, Kyoungwon; Lee, Gae Hwang; Heo, Chul-Joon; Lee, Kwang-Hee; Bulliard, Xavier; Satoh, Ryu-Ichi; Yagi, Tadao; Ro, Takkyun; Im, Dongmo; Jung, Jungkyu; Lee, Myungwon; Lee, Tae-Yon; Han, Moon Gyu; Jin, Yong Wan; Lee, Sangyoon

    2015-01-01

    Complementary metal-oxide-semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor. PMID:25578322

  11. Investigations of nanocomposite magnetic materials based on the oxides of iron, nickel, cobalt and silicon dioxide

    NASA Astrophysics Data System (ADS)

    Gracheva, Irina E.; Olchowik, Grazyna; Gareev, Kamil G.; Moshnikov, Vyatcheslav A.; Kuznetsov, Vladimir V.; Olchowik, Jan M.

    2013-05-01

    This paper is concerned with the study of magnetic nanocomposites containing silicon, iron, nickel, and cobalt oxides. These materials were produced in the form of thin films based on Fe-Si-O, Ni-Co-Si-O and Fe-Ni-Co-Si-O systems and powders based on Fe-Si-O, Ni-Si-O, Co-Si-O and Fe-Ni-Co-Si-O systems using sol-gel technology, through centrifugation, and deposition of ammonia solution. The morphology and magnetic properties of materials in the form of thin films were studied by using the atomic force microscopy. The phase composition, specific surface area and magnetic properties of materials in the form of powders were studied by using the X-ray phase analysis, thermal desorption, vibrational magnetometry and immittance measurements. The dependencies of the main parameters were derived for the magnetic materials from their structure and manufacturing conditions. Ways to optimise the technological processes were proposed, aimed at reducing the size of the magnetic particles in an amorphous lattice.

  12. Exothermic phenomena and hazardous gas release during thermal oxidation of mesoporous silicon powders

    NASA Astrophysics Data System (ADS)

    Loni, A.; Canham, L. T.

    2013-05-01

    We report on the occurrence of exothermic phenomena during the thermal ramping of mesoporous silicon powders in ambient air. For furnace set temperatures of up to 800 °C, discrete exotherms occur during the initial ramp-up stage from room temperature. With an onset around 200 °C, the powder temperature rapidly self-elevates to significantly beyond the concurrent furnace baseline value and cools thereafter, in most cases over a period of a few minutes. A number of periodically spaced exotherms can occur, depending on both the weight and layout of the powder batch. A broadening and amalgamation of exotherms are observed for large batch sizes, indicating a longer-term retention of induced thermal energy, in one case with the powder temperature rising well beyond 1000 °C and being maintained for up to 80 min. We associate these exotherms with dehydrogenation processes, some of which may involve N-H as well as Si-H bonds. Oxidation is accompanied by the release of silanes and hydrogen, care therefore being required to avoid combustion of these pyrophoric gases.

  13. Organic-on-silicon complementary metal-oxide-semiconductor colour image sensors

    NASA Astrophysics Data System (ADS)

    Lim, Seon-Jeong; Leem, Dong-Seok; Park, Kyung-Bae; Kim, Kyu-Sik; Sul, Sangchul; Na, Kyoungwon; Lee, Gae Hwang; Heo, Chul-Joon; Lee, Kwang-Hee; Bulliard, Xavier; Satoh, Ryu-Ichi; Yagi, Tadao; Ro, Takkyun; Im, Dongmo; Jung, Jungkyu; Lee, Myungwon; Lee, Tae-Yon; Han, Moon Gyu; Jin, Yong Wan; Lee, Sangyoon

    2015-01-01

    Complementary metal-oxide-semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor.

  14. Square wave anodic stripping voltammetric determination of Cd²? and Pb²? at bismuth-film electrode modified with electroreduced graphene oxide-supported thiolated thionine.

    PubMed

    Li, Zou; Chen, Li; He, Fang; Bu, Lijuan; Qin, Xiaoli; Xie, Qingji; Yao, Shouzhuo; Tu, Xinman; Luo, Xubiao; Luo, Shenglian

    2014-05-01

    Graphene oxide (GO)-thionine (TH) nanocomposite was prepared by ?-? stacking. The nanocomposite was cast-coated on a glassy carbon electrode (GCE) to prepare an electroreduced GO (ERGO)-TH/GCE, then 2-mercaptoethanesulfonate (MES) was covalently tethered to ERGO-TH by potentiostatic anodization to form an ERGO-TH-MES/GCE. The thiolation reaction was monitored by electrochemical quartz crystal microbalance (EQCM). Square wave anodic stripping voltammetry (SWASV) was used to determine Cd(2+) and Pb(2+) at the ERGO-TH-MES/GCE further modified with Nafion and Bi. Under the optimal conditions, the linear calibration curves for Cd(2+) and Pb(2+) are from 1 to 40 ?g L(-1), with limits of detection (S/N=3) of 0.1 ?g L(-1) for Cd(2+) and 0.05 ?g L(-1) for Pb(2+), respectively. The electrode was used for the simultaneous analysis of Cd(2+) and Pb(2+) in water samples with satisfactory recovery. PMID:24720997

  15. Auger and X-ray PhotoelectronSpectroscopy Study of the Density ofOxygen States in Bismuth, Aluminum, Silicon, and Uranium Oxides

    SciTech Connect

    Teterin, Yu A.; Ivanov, K.E.; Teterin, A. Yu; Lebedev, A.M.; Utkin, I.O.; Vukchevich, L.

    1998-08-03

    The correlation of relative partial electron density at the oxygen ions with the intensity of Auger O KLL lines in Bi2O3, Al2O3, SiO2 and UO2 has been determined by Auger and X-ray photoelectron spectroscopic methods. The dependence of the relative intensities of Auger O KL2-3L2-3 and O KL1L2-3-lines was characterized from the binding energy of O 1s electrons. The electron density of the outer valence levels of oxygen increases as the relative intensities of Anger OKL2-3L2-3 and O KL1L2-3-lines increase. The fine structure observed in the O KL1L2-3 Auger and the O 2s XPS spectra has been explained by the formation of inner valence molecular orbitals (IVMO) from the interaction of electrons of the O 2s and filled metal ns shells.

  16. An interface state mediated junction leakage mechanism induced by a single polyhedral oxide precipitate in silicon diode

    NASA Astrophysics Data System (ADS)

    Tsuchiaki, M.; Fujimori, H.; Iinuma, T.; Kawasaki, A.

    1999-06-01

    The impact of an oxide precipitate on the junction leakage of a silicon p/n diode was investigated. A 70-100 nm diam single polyhedral oxide precipitate was placed in the depletion region of a p+/n junction by hydrogen annealing and polishing a Czochralski grown silicon wafer. In the reverse-bias current-voltage (I-V) curve, an anomalous hump structure was observed. This excess leakage component exhibited a flicker-type low frequency noise. Functional decomposition of the I-V curves demonstrated that a single gap state regulates the leakage current and that two distinct physical processes are involved in the leakage mechanism. The temperature and electric field dependence of the processes revealed that the gap state was a shallow attractive Coulomb center and that electric carriers were supplied to the Coulomb center by phonon-assisted tunneling and emitted from the center by the Poole-Frenkel mechanism. The presence of excessive low frequency noise indicated spatial proximity between the Coulomb center and the oxide precipitate. Computer simulations of the electric field around the oxide precipitate suggested that the center is doubly charged. Based on these findings, a leakage model was proposed. In the vicinity of the oxide precipitate, a few interstitial oxygen atoms are thought to be clustered to form a shallow double donor. The electric field facilitates the hopping of electrons from the valence band into the oxygen donor via interface states on the exterior of the oxide precipitate. Electrons are then emitted onto the conduction band by the Poole-Frenkel mechanism. Charge state transitions of traps inside the oxide precipitate generate a low frequency electric field fluctuation. The field fluctuation is then amplified by the Poole-Frenkel mechanism into the excessive low frequency noise in the leakage current. Thus a clear case of the detrimental impact of a shallow Coulomb center associated with an extended defect is established.

  17. Corrosion inhibition of cobalt in some acid solutions by bismuth(III) chloride

    SciTech Connect

    Itoh, Miki; Ihara, Masaru; Nishihara, Hiroshi; Aramaki, Kunitsugu (Keio Univ., Yokohama (Japan). Dept. of Chemistry)

    1994-02-01

    Inhibition effects of bismuth(III) chloride on cobalt corrosion in 1N HClO[sub 4], 1N H[sub 2]SO[sub 4], and 1N HCl were investigated by polarization measurements and colorimetry of dissolved cobalt ion. More than 85% of the inhibition efficiency was obtained for cobalt in these acid solutions. X-ray photoelectron spectra showed the formation of a protective film which comprises an inner layer composed of metallic bismuth and an outer layer of cobalt(II), bismuth(III), chloride, oxide, and hydroxide ions. Because the cathodic bismuth deposition was stimulated and a uniform layer of bismuth was not formed on the surface, the corrosion reaction was accelerated in 1N HClO[sub 4] at a high concentration of the inhibitor. The inhibition efficiency of the compound for various metals in 1N HClO[sub 4] was confirmed as being associated with a difference in the standard electrode potential between bismuth and a metal.

  18. Solution combustion synthesis and characterization of nanosized bismuth ferrite

    NASA Astrophysics Data System (ADS)

    Sai Kumar, V. Sesha; Rao, K. Venkateswara; Krishnaveni, T.; Kishore Goud, A. Shiva; Reddy, P. Ranjith

    2012-06-01

    The present paper describes a simple method of nanosized BiFeO3 by the solution combustion synthesis using bismuth and iron nitrates as oxidizers and the combination fuel of citric acid and ammonium hydroxide, with fuel to oxidizer ratio (? = 1) one. The X-ray Diffraction results indicated rhombohedral phase (R3m) with JCPDS data card no: 72-2035. The ferroelectric transition of the sample at 8310C was detected by differential thermal analysis. Thermal analysis was done by Thermal gravimetric-Differential thermal analyzer and obtained results were presented in this paper.

  19. Pr doped bismuth ferrite ceramics with enhanced multiferroic properties.

    PubMed

    Uniyal, P; Yadav, K L

    2009-10-01

    Pr modified Bi(0.9-x)La(0.1)Pr(x)FeO(3) (BLPFO-x, x = 0, 0.1 and 0.2) ceramics were prepared by the conventional method based on the solid state reaction of mixed oxides and a detailed study of electrical and magnetic properties of Pr modified bismuth ferrite (BLPFO) is reported. X-ray analysis shows the formation of a bismuth ferrite rhombohedral phase. Pr doping significantly increases the resistivity and leads to a successful observation of electrical polarization hysteresis loops. All the samples have been found to possess a spontaneous magnetic moment at room temperature which increases further at low temperatures. The strong dependence of remnant polarization and dielectric constant on the strength of magnetic field is a direct evidence of magnetoelectric coupling in BLPFO-2 ceramics. PMID:21832425

  20. Aspects of the magmatic geochemistry of bismuth

    USGS Publications Warehouse

    Greenland, L.P.; Gottfried, D.; Campbell, E.Y.

    1973-01-01

    Bismuth has been determined in 74 rocks from a differentiated tholeiitic dolerite, two calc-alkaline batholith suites and in 66 mineral separates from one of the batholiths. Average bismuth contents, weighted for rock type, of the Great Lake (Tasmania) dolerite, the Southern California batholith and the Idaho batholith are, 32, 50 and 70 ppb respectively. All three bodies demonstrate an enrichment of bismuth in residual magmas with magmatic differentiation. Bismuth is greatly enriched (relative to the host rock) in the calcium-rich accessory minerals, apatite and sphene, but other mineral analyses show that a Bi-Ca association is of little significance to the magmatic geochemistry of bismuth. Most of the bismuth, in the Southern California batholith at least, occurs in a trace mineral phase (possibly sulfides) present as inclusions in the rock-forming minerals. ?? 1973.

  1. Potentiometric studies on bismuth ferrocyanide and the determination of bismuth

    Microsoft Academic Search

    Ram Sahai Saxena; C. S. Bhatnagar

    1959-01-01

    The reaction between bismuth nitrate and ferrocyanides of alkali metals such as sodium, potassium, lithium and ammonium, has been studied potentiometrically using platinum as an indicator electrode in conjunction with a saturated calomel electrode through KNO3 bridge. The equivalence point obtained from the maximum value of dE\\/dV corresponds to the formation and complete precipitation of a compound having molecular formula

  2. Photoreductive generation of amorphous bismuth nanoparticles using polysaccharides--bismuth-cellulose nanocomposites.

    PubMed

    Breitwieser, Doris; Kriechbaum, Margit; Ehmann, Heike M A; Monkowius, Uwe; Coseri, Sergiu; Sacarescu, Liviu; Spirk, Stefan

    2015-02-13

    A simple and highly reproducible synthesis of amorphous bismuth nanoparticles incorporated into a polysaccharide matrix using a photoreduction process is presented. As precursor for the generation of the Bi nanoparticles, organosoluble triphenylbismuth is used. The precursor is dissolved in toluene and mixed with a hydrophobic organosoluble polysaccharide, namely trimethylsilyl cellulose (TMSC) with high DSSi. The solution is subjected to UV exposure, which induces the homolytic cleavage of the bismuth-carbon bond in BiPh3 resulting in the formation of Bi(0) and phenyl radicals. The aggregation of the Bi atoms can be controlled in the TMSC matrix and yields nanoparticles of around 20 nm size as proven by TEM. The phenyl radicals undergo recombination to form small organic molecules like benzene and biphenyl, which can be removed from the nanocomposite after lyophilization and exposure to high vacuum. Finally, the TMSC matrix is converted to cellulose after exposure to HCl vapors, which remove the trimethylsilyl groups from the TMSC derivative. Although TMSC is converted to cellulose, the formed TMS-OH is not leaving the nanocomposite but reacts instead with surface oxide layer of the Bi nanoparticles to form silylated Bi nanoparticles as proven by TEM/EDX. PMID:25458299

  3. Electroanalytical detection of Pb, Cd and traces of Cr at micro\\/nano-structured bismuth film electrodes

    Microsoft Academic Search

    Jorge Saturno; Danny Valera; Hermes Carrero; Lenys Fernández

    2011-01-01

    A micro\\/nanoparticle (?-NP) bismuth film electrode (BiFE) has been developed for the determination of lead and cadmium by anodic stripping voltammetry (ASV) and trace levels of chromium by adsorptive stripping voltammetry (AdSV). Chromium was detected in a flow cell. Bismuth was electrodeposited on a hydrated aluminum oxide template, which was previously coated on a glassy-carbon (GC) electrode. Then, the template

  4. Effects of silicon nanostructure evolution on Er{sup 3+} luminescence in silicon-rich silicon oxide/Er-doped silica multilayers

    SciTech Connect

    Chang, Jee Soo; Jhe, Ji-Hong; Yang, Moon-Seung; Shin, Jung H.; Kim, Kyung Joong; Moon, Dae Won [Department of Physics, KAIST, 373-1 Guseong-dong, Yuseong-Gu, Daejon 305-701 (Korea, Republic of); Advanced Industrial Metrology Group, KRISS, Daejon 305-600 (Korea, Republic of)

    2006-10-30

    The effect of silicon nanostructure evolution on Er{sup 3+} luminescence is investigated by using multilayers of 2.5 nm thin SiO{sub x} (x<2) and 10 nm thin Er-doped silica (SiO{sub 2}:Er). By separating excess Si and Er atoms into separate, nanometer-thin layers, the effect of silicon nanostructure evolution on np-Si sensitized Er{sup 3+} luminescence could be investigated while keeping the microscopic Er{sup 3+} environment the same. The authors find that while the presence of np-Si is necessary for efficient sensitization, the overall quality of np-Si layer has little effect on the Er{sup 3+} luminescence. On the other hand, intrusion of np-Si into Er-doped silica layers leads to deactivation of np-Si/Er{sup 3+} interaction, suggesting that there is a limit to excess Si and Er contents that can be used.

  5. Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires

    PubMed Central

    2013-01-01

    Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO. PMID:23590803

  6. Electronic states at the interface between indium tin oxide and silicon

    SciTech Connect

    Malmbekk, H.; Vines, L.; Monakhov, E. V.; Svensson, B. G. [University of Oslo, Physics Department/Center for Materials Science and Nanotechnology, P.O. Box 1048, Blindern, Oslo N-0316 (Norway)

    2011-10-01

    Electronic properties and thermal stability of interfacial states between indium tin oxide (ITO) and monocrystalline silicon (Si) have been investigated. ITO films with thicknesses of about 300 nm were deposited by dc magnetron sputtering on n- and p-type (100) Si at room temperature. The samples were then annealed for 30 min at different temperatures in the range 100-600 deg. C, and the ITO-Si junction was found to exhibit rectifying behavior. Current-voltage (IV), capacitance-voltage (CV), and deep-level transient spectroscopy (DLTS) measurements have been used to electrically characterize the ITO-Si interface. DLTS measurements on p-type Si samples reveal a dominant hole trap at around 0.37 eV above the valence band edge. In the n-type samples, a broad band of electron traps occur in the range 0.1-0.2 eV below the conduction band edge. These electron traps display wide DLTS peaks, indicating a band of electronic energy levels rather than well-defined states originating from isolated point defects. All the traps in both the p- and n-type samples are found to be located near the ITO-Si interface. Investigations of the thermal stability of the observed electronic states show that the dominant hole trap anneal out after 30 min at 250 deg. C, while the dominant electron traps can be stable up to 500 deg. C. IV and DLTS measurements demonstrate a clear correlation between the annealing of the dominant electronic states and increase in the junction rectification.

  7. Statistical contact angle analyses; "slow moving" drops on a horizontal silicon-oxide surface.

    PubMed

    Schmitt, M; Grub, J; Heib, F

    2015-06-01

    Sessile drop experiments on horizontal surfaces are commonly used to characterise surface properties in science and in industry. The advancing angle and the receding angle are measurable on every solid. Specially on horizontal surfaces even the notions themselves are critically questioned by some authors. Building a standard, reproducible and valid method of measuring and defining specific (advancing/receding) contact angles is an important challenge of surface science. Recently we have developed two/three approaches, by sigmoid fitting, by independent and by dependent statistical analyses, which are practicable for the determination of specific angles/slopes if inclining the sample surface. These approaches lead to contact angle data which are independent on "user-skills" and subjectivity of the operator which is also of urgent need to evaluate dynamic measurements of contact angles. We will show in this contribution that the slightly modified procedures are also applicable to find specific angles for experiments on horizontal surfaces. As an example droplets on a flat freshly cleaned silicon-oxide surface (wafer) are dynamically measured by sessile drop technique while the volume of the liquid is increased/decreased. The triple points, the time, the contact angles during the advancing and the receding of the drop obtained by high-precision drop shape analysis are statistically analysed. As stated in the previous contribution the procedure is called "slow movement" analysis due to the small covered distance and the dominance of data points with low velocity. Even smallest variations in velocity such as the minimal advancing motion during the withdrawing of the liquid are identifiable which confirms the flatness and the chemical homogeneity of the sample surface and the high sensitivity of the presented approaches. PMID:25524007

  8. Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires.

    PubMed

    Chong, Su Kong; Dee, Chang Fu; Abdul Rahman, Saadah

    2013-01-01

    Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO. PMID:23590803

  9. New bismuth calcium oxysilicate with apatite structure: Synthesis and structural characterization

    SciTech Connect

    Uvarov, Vladimir, E-mail: vladimiru@savion.huji.ac.i [Unit for Nanoscopic Characterization, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Shenawi-Khalil, Sanaa [Casali Institute of Applied Chemistry, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Popov, Inna [Unit for Nanoscopic Characterization, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2010-07-15

    New bismuth calcium silicon oxide Ca{sub 4}Bi{sub 4.3}(SiO{sub 4})(HSiO{sub 4}){sub 5}O{sub 0.95}, with apatite structure has been synthesized. The structure was refined from powder X-ray diffraction data. The refinement revealed that the phase has P6{sub 3}/m (176) space group with unit cell parameters a=b=9.6090(7) A, c=7.0521(7) A, V=563.9 A{sup 3} and c/a=0.734. The R{sub wp} factor at Rietveld refinement was equal to 0.082. The synthesized phase has an unusual quantity of cation vacancies in a crystal lattice. Mechanisms of compensation of the excess charge of a lattice are considered and checked experimentally using the FT-IR spectroscopy, the thermal analysis and the XPS analysis. - Graphical abstract: The fragment Ca{sub 4}Bi{sub 4.3}(SiO{sub 4})(HSiO{sub 4}){sub 5}O{sub 0.95} structure along c-axis in polygonal mode.

  10. Deposition and Characterization of Silicon-Germanium Alloy Thin Films on Oxide.

    NASA Astrophysics Data System (ADS)

    Tsai, Julie Ann

    1995-01-01

    Polycrystalline silicon-germanium (rm Si_{1-it x}Ge_{it x}) alloy films are a novel class of electronic materials for use in thin-film transistors (TFTs) and other thin film applications. This thesis describes the development of a deposition technology for rm Si_ {1-it x}Ge_{it x} alloy thin films on oxide and the characterization of structural and electrical properties of the resulting polycrystalline rm Si_{1-it x}Ge_{it x} films. rm Si_{1-it x }Ge_{it x} alloy thin films have been formed on oxide-coated Si substrates by Plasma-Enhanced Very-Low-Pressure Chemical Vapor Deposition (PE-VLPCVD). The deposition of polycrystalline films by the pyrolysis of rm SiH_4 and rm GeH_4 gases at temperatures {<=}600^circrm C has been accomplished by two methods: thermal growth on a thin Si buffer layer (VLPCVD) and plasma-enhanced deposition on oxide (PE-VLPCVD). Plasma-enhanced deposition also results in direction deposition of poly-rm Si_{1-it x}Ge_{it x} onto oxide as well as improved structural film properties such as smoother surface morphology and a more columnar, { 220} -dominant grain texture. Deposition by PE-VLPCVD of amorphous rm Si_{1-it x}Ge_{ it x} followed by a crystallization anneal in rm N_2 at 600^ circrm C forms poly-rm Si_{1-it x}Ge_{it x} films having even smoother surface morphologies compared to plasma-deposited poly-rm Si_ {1-it x}Ge_{it x} films, with grain sizes enlarged by an order of magnitude and a weak { 111} grain texture typical of thermally-grown poly-Si films. Recrystallization of rm Si^+ implant-amorphized poly-rm Si_ {1-it x}Ge_{it x} films at 600^circrm C results in a modified polycrystalline rm Si_{1-it x}Ge_{ it x} film with surface morphologies not quite as smooth as amorphous-crystallized films but with the largest observed grain sizes, up to 1.3 murm m in 25% Ge films of 1000A thickness. The effects of Ge on the electrical properties of dopant-implanted poly-rm Si_{1 -it x}Ge_{it x} films were also studied. For n-type films, poly- rm Si_{1-it x}Ge_{ it x} resistivities are comparable to that of poly-Si, with similar grain boundary barrier heights; p-type poly-rm Si_{1-it x}Ge_{it x} films, on the other hand, have lower resistivities than p-type poly-Si with potential barrier heights that decrease dramatically with Ge content. At lower dopant concentrations, the improvements in poly-rm Si_{1-it x}Ge _{it x} resistivities become more pronounced; at higher dopant concentrations, conduction becomes limited by scattering within the grains. Top-gate self-aligned poly-rm Si _{0.82}Ge_{0.18} thin-film transistor devices (TFTs) were fabricated with a maximum process temperature of 620^circ rm C. The process of plasma hydrogenation is effective at improving device characteristics, with rm Si_{1-it x}Ge_ {it x} TFTs responding just as well if not better to hydrogenation compared to Si TFTs. Although device properties improve quite dramatically, estimated grain boundary trap state densities extracted from transfer characteristics remain higher in rm Si_ {1-it x}Ge_{x} than in Si and may be attributed to a high density of Ge dangling bonds at the gate dielectric interface. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.) (Abstract shortened by UMI.).

  11. Thermal expansion of bismuth telluride

    Microsoft Academic Search

    L. M. Pavlova; Yu. I. Shtern; R. E. Mironov

    2011-01-01

    The results of X-ray and dilatometric measurements of the thermal expansion of bismuth telluride in the temperature range\\u000a of 4.2–850 K have been critically analyzed. The joint statistical processing of the experimental data has been performed by\\u000a the least squares method and the most reliable temperature dependences of the linear thermal expansion coefficients along\\u000a the principal crystallographic axes ?\\u000a a

  12. Heated ion implantation for high-performance and highly reliable silicon-on-insulator complementary metal–oxide–silicon fin field-effect transistors

    NASA Astrophysics Data System (ADS)

    Mizubayashi, Wataru; Onoda, Hiroshi; Nakashima, Yoshiki; Ishikawa, Yuki; Matsukawa, Takashi; Endo, Kazuhiko; Liu, Yongxun; O’uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Migita, Shinji; Morita, Yukinori; Ota, Hiroyuki; Masahara, Meishoku

    2015-04-01

    We have investigated the impact of heated ion implantation (I/I) on the performance and reliability of silicon-on-insulator (SOI) complementary metal–oxide–silicon (CMOS) fin field-effect transistors (FinFETs). An implantation temperature equal to and higher than 400 °C is needed to maintain the crystallinity of the Si substrate during I/I within the experimental conditions of ion species, implantation energy, and ion dose in this study. By heated I/I at 500 °C, the 11-nm-thick SOI layer perfectly maintains the crystallinity even after I/I, and a defect-free crystal is obtained by activation annealing. It was clarified that the cap layer is essential for the suppression of the out-diffusion during heated I/I. Heated I/I on the source and drain improves the on-current–off-current (Ion–Ioff), threshold voltage (Vth) variability, and bias temperature instability (BTI) characteristics of nMOS and pMOS FinFETs as compared with those after room-temperature I/I.

  13. Controlling Er-Tm interaction in Er and Tm codoped silicon-rich silicon oxide using nanometer-scale spatial separation for efficient, broadband infrared luminescence

    SciTech Connect

    Seo, Se-Young; Shin, Jung H. [Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejon (Korea, Republic of)

    2004-11-01

    The effect of nanometer-scale spatial separation between Er{sup 3+} and Tm{sup 3+} ions in Er and Tm codoped silicon-rich silicon oxide (SRSO) films is investigated. Er and Tm codoped SRSO films, which consist of nanocluster Si (nc-Si) embedded inside SiO{sub 2} matrix, were fabricated with electron cyclotron resonance-plasma enhanced chemical vapor deposition of SiH{sub 4} and O{sub 2} with concurrent sputtering of Er and Tm metal targets. Spatial separation between Er{sup 3+} and Tm{sup 3+} ions was achieved by depositing alternating layers of Er- and Tm-doped layers of varying thickness while keeping the total film thickness the same. The films display broadband infrared photoluminescence (PL) from 1.5 to 2.0 {mu}m under a single source excitation due to simultaneous excitation of Er{sup 3+} and Tm{sup 3+} ions by nc-Si. Increasing the layer thickness from 0 to 72 nm increases the Er{sup 3+} PL intensity nearly 50-fold while the Tm{sup 3+} PL intensity is unaffected. The data are well-explained by a model assuming a dipole-dipole interaction between excited Er{sup 3+} and Tm{sup 3+} ions, and suggest that by nanoscale engineering, efficient, ultrabroadband infrared luminescence can be obtained in an optically homogeneous material using a single light source.

  14. Controlling the shape and gap width of silicon electrodes using local anodic oxidation and anisotropic TMAH wet etching

    NASA Astrophysics Data System (ADS)

    Rouhi, Jalal; Mahmud, Shahrom; Derita Hutagalung, Sabar; Naderi, Nima; Kakooei, Saeid; Johar Abdullah, Mat

    2012-06-01

    A simple method for fabricating silicon electrodes with various shapes and gap widths was designed using the special properties of anisotropic tetramethylammonium hydroxide (TMAH) wet etching and local anodic oxidation (LAO). A statistical system was used for the optimization of the parameters of the LAO process to facilitate a better understanding and precise analysis of the process. Analyses of the interaction effects among the significant factors of LAO showed that the relative humidity and applied voltage were interdependent. They had the strongest interaction effect on the dimensions of the oxide mask. TMAH with a concentration of 25% was used as an etchant solution in (1?0?0) silicon with a rectangular oxide mask. The observed undercutting at convex corners, tip shape of emitters and gap widths of electrodes were exactly consistent with theoretical studies. Combination of the LAO method and anisotropic TMAH wet etching was successfully used to fabricate Si nano-gap electrodes. This fabrication method of sharp and round tip emitters was simple, controllable and faster than common techniques. These results indicate that the method can be a new approach for studying the electrical properties of nano-gap electrodes.

  15. Thickness-dependent optimization of Er3+ light emission from silicon-rich silicon oxide thin films

    PubMed Central

    2011-01-01

    This study investigates the influence of the film thickness on the silicon-excess-mediated sensitization of Erbium ions in Si-rich silica. The Er3+ photoluminescence at 1.5 ?m, normalized to the film thickness, was found five times larger for films 1 ?m-thick than that from 50-nm-thick films intended for electrically driven devices. The origin of this difference is shared by changes in the local density of optical states and depth-dependent interferences, and by limited formation of Si-based sensitizers in "thin" films, probably because of the prevailing high stress. More Si excess has significantly increased the emission from "thin" films, up to ten times. This paves the way to the realization of highly efficient electrically excited devices. PMID:21711930

  16. Silicon heterojunction solar cells with high surface passivation quality realized using amorphous silicon oxide films with epitaxial phase

    NASA Astrophysics Data System (ADS)

    Nakada, Kazuyoshi; Irikawa, Junpei; Miyajima, Shinsuke; Konagai, Makoto

    2015-05-01

    The epitaxial growth of the i-layer of crystalline silicon heterojunction solar cells has been widely accepted as harmful to surface passivation. In our experiments, however, although a very rough epitaxial phase in the intrinsic a-Si1?xOx:H passivation layer was confirmed by transmission electron microscopy and spectroscopic ellipsometry, a high effective lifetime and an implied-VOC of over 720 mV were achieved with lifetime samples. The high passivation quality was confirmed by the obtained open circuit voltages of 728 and 721 mV for n- and p-type solar cells, respectively, with an a-Si1?xOx:H/p-µc-Si1?xOx:H stack rear structure. These results indicate that, contrary to the common knowledge, high surface passivation quality can be achieved even when the epitaxial phase is present.

  17. Structural, morphology and electrical studies on ferroelectric bismuth titanate thin films prepared by sol–gel technique

    Microsoft Academic Search

    N. V. Giridharan; S. Madeswaran; R. Jayavel

    2002-01-01

    Crystal structure, surface morphology, compositional homogeneity and electrical properties of layered perovskite bismuth titanate (BTO) thin films have been investigated. BTO thin films were deposited on silicon and platinum-coated silicon substrates by spin coating. X-ray diffraction analysis confirms that the crystallinity of the films increases with increasing annealing temperature and the optimum temperature is found to be 600°C. Morphology studies

  18. Wettability effect of graphene-based surfaces on silicon carbide and their influence on hydrophobicity of nanocrystalline cerium oxide films.

    PubMed

    Souza, Jean C; Neckel, Itamar T; Varalda, Jose; Ribeiro, Evaldo; Schreiner, Wido H; Mosca, Dante H; Sierakowski, Maria-Rita; Fernandes, Vilmar; Ouerghi, Abdelkarim

    2015-03-01

    We investigate the water-repellent ability of graphene-based surfaces stabilized on silicon carbide (SiC) and the nanocrystalline cerium oxide (CeO2) films electrodeposited on them. Water contact angle is revealed strongly dependent on the number of graphene monolayers on SiC, indicating partial permeability of graphene on SiC. Fluctuations in the roughness of textured surfaces as well as variations of oxygen vacancy content in CeO2 electrodeposits are determinant for the hydrophobicity of the interaction between water droplets and nanocrystalline CeO2 electrodeposits on monolayers graphene on SiC. PMID:25490565

  19. Nanoporous silicon prepared through air-oxidation demagnesiation of Mg2Si and properties of its lithium ion batteries.

    PubMed

    Liang, Jianwen; Li, Xiaona; Hou, Zhiguo; Guo, Cong; Zhu, Yongchun; Qian, Yitai

    2015-04-28

    Nanoporous silicon has been prepared through the air-oxidation demagnesiation of Mg2Si at 600 °C for 10 hours (Mg2Si + O2 ? Si + MgO), followed by HCl washing. Mg2Si was prepared from 200 mesh commercial Si at 500 °C for 5 h in an autoclave. The as-prepared Si exhibits a reversible capacity of 1000 mA h g(-1) at 36 A g(-1) and ?1200 mA h g(-1) at 1.8 A g(-1) over 400 cycles. PMID:25812916

  20. Study of the use of Metal-Oxide-Silicon (MOS) devices for particulate detection and monitoring in the earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Brooks, A. D.; Monteith, L. K.; Wortman, J. J.; Mulligan, J. C.

    1974-01-01

    A metal-oxide-silicon (MOS) capacitor-type particulate sensor was evaluated for use in atmospheric measurements. An accelerator system was designed and tested for the purpose of providing the necessary energy to trigger the MOS-type sensor. The accelerator system and the MOS sensor were characterized as a function of particle size and velocity. Diamond particles were used as particulate sources in laboratory tests. Preliminary tests were performed in which the detector was mounted on an aircraft and flown in the vicinity of coal-fired electric generating plants.

  1. Critical Oxide Thickness for Efficient Single-walled Carbon Nanotube Growth on Silicon Using Thin SiO2 Diffusion Barriers

    Microsoft Academic Search

    J. M. Simmons; B. M. Nichols; Matthew S. Marcus; O. M. Castellini; R. J. Hamers; M. A. Eriksson

    2007-01-01

    The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand the range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth of single-walled carbon nanotubes on bare silicon and on ultra-thin oxides is greatly inhibited due to the formation of a non-catalytic silicide. Using x-ray photoelectron spectroscopy, we

  2. Critical oxide thickness for efficient single-walled carbon nanotube growth on silicon using thin SiO2 diffusion barriers

    Microsoft Academic Search

    Robert J. Hamers

    2006-01-01

    The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand their range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth of single-walled carbon nanotubes on bare silicon and on ultrathin oxides is greatly inhibited due to the formation of a noncatalytic silicide. Using X-ray photoelectron spectroscopy, we

  3. Coprecipitation of polonium with bismuth phosphate

    Microsoft Academic Search

    Z. Hölgye

    2007-01-01

    It was found that Po(IV) coprecipitates to a high degree with bismuth phosphate from weakly acidic solutions. The degree of\\u000a coprecipitation of Po(II) under the same conditions is substantially lower. Coprecipitation with bismuth phosphate can be\\u000a utilized for the separation of polonium from inorganic salts present in urine.

  4. The photoluminescence and structural properties of (Ce, Yb) co-doped silicon oxides after high temperature annealing

    NASA Astrophysics Data System (ADS)

    Heng, C. L.; Li, J. T.; Su, W. Y.; Yin, P. G.; Finstad, T. G.

    2015-01-01

    We studied the photoluminescence (PL) and structural properties of Ce and Yb co-doped silicon oxide films after high temperature annealing. The PL spectra of Ce3+ and Yb3+ ions were sensitive to the structural variation of the films, and the Yb PL intensities were significantly enhanced especially upon 1200 °C annealing. X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, indicated that rare earth silicates and the CeO2 phase had formed in the oxides. The proportions of the phases varied with the "nominal Si-richness" of the films. Energy transfer from the excited Ce3+ to Yb3+ can be inferred from both PL excitation and decay spectra.

  5. Electron energy-loss spectroscopy analysis of interface structure of yttrium oxide gate dielectrics on silicon

    Microsoft Academic Search

    D. Niu; R. W. Ashcraft; G. N. Parsonsa

    Interface stability of high dielectric constant gate insulators on silicon is an important issue for advanced gate stack engineering. In this article, we analyze the silicon\\/dielectric interface structure for thin Y2O3 and Y silicate films deposited by chemical vapor deposition on clean and prenitrided Si~100! using high-resolution transmission electron microscopy, electron energy-loss spectroscopy, and x-ray photoelectron spectroscopy. The analysis shows

  6. In situ spectroscopic ellipsometry study of the oxide etching and surface damaging processes on silicon under hydrogen plasma

    SciTech Connect

    Vargas, I.M.; Manso, J.Y.; Guzman, J.R.; Weiner, B.R.; Morell, G.

    2000-07-01

    The authors employed in situ ellipsometry in the monitoring of surface damage to monocrystalline silicon (Si) substrates under hydrogen plasma conditions. These measurements were complemented with spectroscopic ellipsometry and Raman spectroscopy, in order to characterize the surface conditions. It was found that heating the Si substrate to 700 C in the presence of molecular hydrogen produces etching of the native oxide layer, which is typically 10 {angstrom} thick. When the already hot and bare silicon surface is submitted to hydrogen plasma, it deteriorates very fast, becoming rough and full of voids. Modeling of the spectroscopic ellipsometry data was used to obtain a quantitative physical picture of the surface damage, in terms of roughness layer thickness and void fraction. The results indicate that by the time a thin film starts to grow on these silicon surfaces, like in the chemical vapor deposition of diamond, the roughness produced by the hydrogen plasma has already determined to a large extent the rough nature of the film to be grown.

  7. VOLUME 82, NUMBER 2 P H Y S I C A L R E V I E W L E T T E R S 11 JANUARY 1999 Universal Mechanism for Gas Adsorption and Electron Trapping on Oxidized Silicon

    E-print Network

    Van Driel, Henry M.

    for Gas Adsorption and Electron Trapping on Oxidized Silicon N. Shamir,* J. G. Mihaychuk, and H. M. van gases (such as He, Ar, H2, O2, N2, CO) experience adsorption at oxidized silicon surfaces at 300 K via electrostatic coupling. This is deduced using contact potential measurements of the work function for gas

  8. Isotopic labeling studies of interactions of nitric oxide and nitrous oxide with ultrathin oxynitride layers on silicon

    E-print Network

    Gustafsson, Torgny

    Isotopic labeling studies of interactions of nitric oxide and nitrous oxide with ultrathin depth profiling using medium energy ion scattering and isotopic labeling methods. We observe that, after atoms are incorporated near the SiO2/Si interface.3,7,17,20­22 A recent isotopic labeling study using

  9. Structural and Oxidative Changes in the Kidney of Crucian Carp Induced by Silicon-Based Quantum Dots

    PubMed Central

    Petrache, Sorina Nicoleta; Stanca, Loredana; Serban, Andreea Iren; Sima, Cornelia; Staicu, Andreia Cristina; Munteanu, Maria Cristina; Costache, Marieta; Burlacu, Radu; Zarnescu, Otilia; Dinischiotu, Anca

    2012-01-01

    Silicon-based quantum dots were intraperitoneally injected in Carassius auratus gibelio specimens and, over one week, the effects on renal tissue were investigated by following their distribution and histological effects, as well as antioxidative system modifications. After three and seven days, detached epithelial cells from the basal lamina, dilated tubules and debris in the lumen of tubules were observed. At day 7, nephrogenesis was noticed. The reduced glutathione (GSH) concentration decreased in the first three days and started to rise later on. The superoxide dismutase (SOD) activity increased only after one week, whereas catalase (CAT) was up-regulated in a time-dependent manner. The activities of glutathione reductase (GR) and glutathione peroxidise (GPX) decreased dramatically by approximately 50% compared to control, whereas the glutathione-S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH) increased significantly after 3 and 7 days of treatment. Oxidative modifications of proteins and the time-dependent increase of Hsp70 expression were also registered. Our data suggest that silicon-based quantum dots induced oxidative stress followed by structural damages. However, renal tissue is capable of restoring its integrity by nephron development. PMID:22949855

  10. Fabrication of porous silicon membranes 

    E-print Network

    Yue, Wing Kong

    1988-01-01

    The Microstructure of Porous Silicon on Heavily Doped Substrates The Microstructure of Porous Silicon on Slightly Doped Substrates The FIPOS Process Si ? MBE on Porous Silicon The InsuRicient Oxidation The First Reaction Cell The Second Reaction Cell A... of Porous Silicon Film on P Type Wafers Thickness of Porous Silicon Film on P+ Wafers Current Density versus Voltage on N+ and P+ Silicon Wafers Current Density ? Voltage Characteristics on the P+ Silicon Wafer . The Reaction Cell for the Fabrication...

  11. Index of refraction versus oxygen partial pressure for tantalum oxide and silicon dioxide films produced by ion beam deposition

    SciTech Connect

    Goward, W.D.; Petersen, H.E.; Dijaili, S.P.; Walker, J.D.

    1998-04-30

    Tantalum oxide and silicon oxide films were made using an ion beam sputtering system. It was found that even though these films were deposited from oxide targets, additions of oxygen were necessary to achieve stoichiometry and hence index of refraction. It was observed that the tantalum oxide target changed color from white to gray, indicating that the oxygen was being depleted from the target. The addition of oxygen to the chamber during deposition replenished the target and improved film stoichiometry. The deposition rate decreased with increasing oxygen partial pressure. It was experimentally determined that by varying the oxygen partial pressure and keeping all other variables fixed, the index of refraction of the film changed in a predictable manner. That is, as the oxygen partial pressure was increased, the index decreased rapidly initially and then reached a saturation point where it stayed fixed with oxygen content. With this data a coating process can be set up using the minimum amount of oxygen (thus increasing filament lifetime) to produce a fully stoichiometric film that has a fixed index. This paper will present the details of these observations and results.

  12. Silicon carbide as an oxidation-resistant high-temperature material. 1: Oxidation and heat corrosion behavior

    NASA Technical Reports Server (NTRS)

    Schlichting, J.

    1981-01-01

    The oxidation and corrosion behavior of SiC (in the form of a SiC powder) and hot-pressed and reaction-bound material were studied. The excellent stability of SiC in an oxidizing atmosphere is due to the development of protective SiO2 coatings. Any changes in these protective layers (e.g., due to impurities, reaction with corrosive media, high porosity of SiC, etc.) lead in most cases to increased rates of oxidation and thus restrict the field of SiC application.

  13. Probing bismuth ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic bismuth

    SciTech Connect

    Chaturvedi, Smita; Rajendra, Ranguwar; Ballav, Nirmalya; Kulkarni, Sulabha, E-mail: s.kulkarni@iiserpune.ac.in [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008 (India); Sarkar, Indranil [DESY Photon Science, Deutsches Elektronen-Synchrotron, 22607 Hamburg (Germany); Shirolkar, Mandar M. [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Jeng, U-Ser; Yeh, Yi-Qi [National Synchrotron Radiation Research Center, 101, Hsin-Ann Road, Science Park, Hsinchu 3007-6, Taiwan (China)

    2014-09-08

    We have investigated bismuth ferrite nanoparticles (?75?nm and ?155?nm) synthesized by a chemical method, using soft X-ray (1253.6?eV) and hard X-ray (3500, 5500, and 7500?eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg K? (1253.6?eV) source showed that iron and bismuth were present in both Fe{sup 3+} and Bi{sup 3+} valence states as expected for bismuth ferrite. However, hard X-ray photoelectron spectroscopy analysis of the bismuth ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi{sup 0} valence state below the surface region, indicating that bismuth ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.

  14. Kinetics of enhanced thermal oxidation of silicon carbide using amorphization by ion implantation

    SciTech Connect

    Alok, D.; Baliga, B.J. [North Carolina State Univ., Raleigh, NC (United States). Power Semiconductor Research Center

    1997-03-01

    The kinetics of a thermal oxidation scheme with enhanced growth rate for 6H-SiC is reported in this paper. This scheme is based upon the formation of a thick amorphous layer created using high-dose ion implantation followed by thermal oxidation. The oxide thickness has been demonstrated to be larger in the amorphized region, when compared to the unimplanted (monocrystalline SiC) region, after dry oxidation. The oxide growth rate was parabolic in nature in the amorphized region, in contrast to a mixed linear-parabolic growth rate observed for the monocrystalline region.

  15. Comparison of rheological, thermal and electrical properties of poly(ethylene oxide) composites with micro and nano sized silicon dioxide filler

    Microsoft Academic Search

    Martin Reading; Alun S. Vaughan

    2010-01-01

    Polyethylene oxide (PEO) is a water-soluble polymer often used as a model system to observe filler effects. This paper details an investigation into the physical, thermal and electrical properties of polyethylene oxide composites containing micro-(SD) and nano-silicon dioxide (nSD) filler. Three molecular weight host PEOs were used - 100,000 g mol-1, 400,000 g mol-1 and 1,000,000 g mol-1 and the

  16. A novel in-situ method for inhibiting surface roughening during the thermal oxide desorption etching of silicon and gallium arsenide

    NASA Astrophysics Data System (ADS)

    Pun, Arthur Fong-Yuen

    A method inhibiting surface roughening of silicon and gallium arsenide wafers during the thermal desorption of their native oxide layers is proposed and tested experimentally, with silicon results indicating a 75% reduction in surface roughness from an averaged value of 2.20 nm to 0.56 nm, and gallium arsenide results indicating a 76% reduction from an averaged surface roughness of 1.6 nm to 0.4 nm. This method does not significantly alter the semiconductor crystalline surface, thus retaining suitability for subsequent epitaxial growth, as demonstrated experimentally. The method is readily implementable in currently utilized deposition systems, subject to the requirements of material growth, substrate heating, and producing a non-oxidizing environment, either inert atmosphere or reduced pressures. The technique involves depositing a thin sacrificial film directly onto the native oxide surface at lower temperatures, of which the thickness is dependent on both the native oxide thickness and the oxide stochiometry initially present within the oxide layer, but has been found experimentally to be on the order of 0.5 nm -- 4 nm for a 2 nm to 4 nm air-formed native oxide layer. Upon heating this structure to high temperatures, the native oxide preferentially reacts with the sacrificial deposited film instead of the bulk wafer, resulting in the chemical reduction to volatile components, which are evaporated at these temperatures. This method is developed for silicon and gallium arsenide and examined experimentally utilizing atomic force microscopy and reflection high-energy electron diffraction. Different native oxide preparation techniques are theorized to yield varying chemical stochiometries, with experimental results elucidating information regarding these differences. Further, a modified tri-layer implementation, in which the deposited film is re-oxidized, is tested for applicability as a novel wafer pacification technique.

  17. Use of sol-gels in the application of ceramic oxide thin films

    SciTech Connect

    Paulson, B.A.

    1987-01-01

    Metal oxide sol-gels were produced through a controlled hydrolysis-condensation reaction of the metal alkoxide in alcohol using nitric acid as a catalyst. In obtaining sols of niobia, tantala, and titania, increasing either the water content or the system concentration increased the rate of gelation. However, while a sufficient amount of nitric acid was required to promote the condensation of the metal oxide and inhibit the precipitation, increasing the amount of nitric acid beyond that point slowed the gelation rate. A sufficient excess of water also lead to precipitation. These systematic parameter investigations were used to obtain sols of bismuth oxide, germania, yttria, and zirconia. The single component sols were characterized and used to make thin films on silicon wafers. The single-component sols were used to make binary oxide sols - barium titanate, lithium niobate, and lithium tantalate. By altering the stoichiometric ratios of the constituent cations, different compounds were produced for dielectric characterization with an AC bridge circuit.

  18. Real-time observation of initial stages of copper film growth on silicon oxide using reflection high-energy electron diffraction

    E-print Network

    Wang, Gwo-Ching

    Real-time observation of initial stages of copper film growth on silicon oxide using reflection-3590 (Received 21 June 2004; accepted 8 September 2004) We have studied, in real time, the evolution of a thin high-energy electron diffraction (RHEED), the structural evolution was monitored in real time

  19. Integration of a stack of two fluorine doped silicon oxide thin films with interconnect metallization for a sub-0.35 ?m inter-metal dielectric application

    Microsoft Academic Search

    L. Baud; G. Passemard; Y. Gobil; H. M'Saad; A. Corte; F. Pires; P. Fugier; P. Noel; P. Rabinzohn; I. Beinglass

    1997-01-01

    Fluorine doped silicon oxide films were deposited on HDP-CVD system and on PECVD system to realize a stack to be integrated in metal lines' architecture. Resistance to moisture absorption of both films was investigated by film exposure in humid atmosphere for 1 week followed by an annealing. Physical properties of uncapped FSG films were measured before and after test in

  20. Detecting Hazardous Gas Analytes Using Porous Silicon Sensors Coated with Metal Oxide Nanoparticles Eddie Goude, University of Florida Georgia Tech SURF 2011

    E-print Network

    Li, Mo

    Detecting Hazardous Gas Analytes Using Porous Silicon Sensors Coated with Metal Oxide Nanoparticles platform with two probes connected to the gold contacts on the sensor and a gas pipe on top of the sensor Graduate Mentor: William Laminack Introduction Gas detectors are utilized to detect odorless and

  1. Light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst

    E-print Network

    Pijpers, Joep J. H.

    Integrating a silicon solar cell with a recently developed cobalt-based water-splitting catalyst (Co-Pi) yields a robust, monolithic, photo-assisted anode for the solar fuels process of water splitting to O2 at neutral pH. ...

  2. A scalable silicon microreactor for preferential CO oxidation: performance comparison with a tubular

    E-print Network

    Gulari, Erdogan

    technology for the development of compact fuel processing systems as compared to packed-bed reactor technology which does not scale down in a feasible manner. A microchannel reactor was fabricated in silicon encoun- tered in conventional power generation, while emitting only water as the exhaust. This technology

  3. Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface

    NASA Astrophysics Data System (ADS)

    Nichau, A.; Schnee, M.; Schubert, J.; Besmehn, A.; Rubio-Zuazo, J.; Breuer, U.; Bernardy, P.; Holländer, B.; Mücklich, A.; Castro, G. R.; von Borany, J.; Buca, D.; Mantl, S.

    2013-04-01

    Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important.

  4. Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface.

    PubMed

    Nichau, A; Schnee, M; Schubert, J; Besmehn, A; Rubio-Zuazo, J; Breuer, U; Bernardy, P; Holländer, B; Mücklich, A; Castro, G R; von Borany, J; Buca, D; Mantl, S

    2013-04-21

    Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important. PMID:23614438

  5. Oxidation kinetics of chemically vapor-deposited silicon carbide in wet oxygen

    Microsoft Academic Search

    Elizabeth J. Opila

    1994-01-01

    The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen at temperatures between 1,200 and 1,400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the

  6. Influence of alumina reaction tube impurities on the oxidation of chemically-vapor-deposited silicon carbide

    Microsoft Academic Search

    Elizabeth Opila

    1995-01-01

    Pure coupons of chemically vapor deposited (CVD) SiC oxidized for 100 h in dry flowing oxygen at 1,300 C. The oxidation kinetics were monitored using thermogravimetry (TGA). The experiments were first performed using high-purity alumina reaction tubes. The experiments were then repeated using fused quartz reaction tubes. Differences in oxidation kinetics, scale composition, and scale morphology were observed. These differences

  7. Modification of optical and electrical properties of zinc oxide-coated porous silicon nanostructures induced by swift heavy ion

    PubMed Central

    2012-01-01

    Morphological and optical characteristics of radio frequency-sputtered zinc aluminum oxide over porous silicon (PS) substrates were studied before and after irradiating composite films with 130?MeV of nickel ions at different fluences varying from 1?×?1012 to 3?×?1013 ions/cm2. The effect of irradiation on the composite structure was investigated by scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence spectroscopy. Current–voltage characteristics of ZnO-PS heterojunctions were also measured. As compared to the granular crystallites of zinc oxide layer, Al-doped zinc oxide (ZnO) layer showed a flaky structure. The PL spectrum of the pristine composite structure consists of the emission from the ZnO layer as well as the near-infrared emission from the PS substrate. Due to an increase in the number of deep-level defects, possibly oxygen vacancies after swift ion irradiation, PS-Al-doped ZnO nanocomposites formed with high-porosity PS are shown to demonstrate a broadening in the PL emission band, leading to the white light emission. The broadening effect is found to increase with an increase in the ion fluence and porosity. XRD study revealed the relative resistance of the film against the irradiation, i.e., the irradiation of the structure failed to completely amorphize the structure, suggesting its possible application in optoelectronics and sensing applications under harsh radiation conditions. PMID:22748164

  8. Influence of Alumina Reaction Tube Impurities on the Oxidation of Chemically-Vapor-Deposited Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth

    1995-01-01

    Pure coupons of chemically vapor deposited (CVD) SiC were oxidized for 100 h in dry flowing oxygen at 1300 C. The oxidation kinetics were monitored using thermogravimetry (TGA). The experiments were first performed using high-purity alumina reaction tubes. The experiments were then repeated using fused quartz reaction tubes. Differences in oxidation kinetics, scale composition, and scale morphology were observed. These differences were attributed to impurities in the alumina tubes. Investigators interested in high-temperature oxidation of silica formers should be aware that high-purity alumina can have significant effects on experiment results.

  9. Selective adsorption of bismuth telluride nanoplatelets through electrostatic attraction.

    PubMed

    Guo, Lingling; Aglan, Amira; Quan, Haiyu; Sun, Junjie; Tang, Chaolong; Song, Jinhui; Szulczewski, Greg; Wang, Hung-Ta

    2014-06-21

    We demonstrate a facile technique to assemble solution phase-synthesized bismuth telluride (Bi2Te3) nanoplatelets into arrays of micropatterns. Aminosilane self-assembled monolayers (SAMs) are printed on silicon dioxide (SiO2) substrates using microcontact printing (?CP). The SAM printed surfaces are terminated with amine-groups allowing Bi2Te3 nanoplatelet selective adsorption by electrostatic attraction. Using Kelvin probe force microscopy, the electrical potential difference between aminosilane SAM and Bi2Te3 nanoplatelet surfaces is found to be ?650 mV, which is larger than that (?400 mV) between the SiO2 substrate and Bi2Te3 nanoplatelet surfaces. The selective adsorption provides an opportunity for integrating solution phase-grown topological insulators toward several device-level applications. PMID:24789217

  10. Magnetoconductivity of Dirac electrons in bismuth

    NASA Astrophysics Data System (ADS)

    Owada, Mitsuaki; Fuseya, Yuki

    2015-04-01

    The magnetoconductivity of bismuth is theoretically investigated on the basis of the Kubo formula to interpret the longstanding mystery of linear magnetoresistance in bismuth. First, the magnetoconductivity for the isotropic Dirac model is studied. It is found that the inverse magnetoconductivity increases quadratically at low magnetic fields and is saturated at high fields. This high field property is in contrast to that obtained by the semiclassical theory, where the inverse magnetoconductivity keeps quadratic increase. Next, the magnetoconductivity for the extended Dirac model, which is a realistic model for bismuth, is studied. The inverse magnetoconductivity so obtained is not saturated, but is reduced at high fields. Implications of present results to the linear magnetoresistivity of bismuth are discussed.

  11. The 1200 C cyclic oxidation behavior of two nickel-aluminum alloys (Ni3AL and NiAl) with additions of chromium, silicon, and titanium

    NASA Technical Reports Server (NTRS)

    Lowell, C. E.; Santoro, G. J.

    1972-01-01

    The alloys Ni3Al and NiAl with and without 1 and 3 atomic percent chromium, silicon, and titanium replacing the aluminum were cyclically oxidized at 1200 C for times to 200 hours, and the results were compared with those obtained with the alloy B-1900 subjected to the same oxidation process. The evaluation was based on metal recession, specific weight change, metallography, electron microprobe analysis, and X-ray diffraction. The oxidation resistance of Ni3Al was improved by Si, unaffected by Ti, and degraded by Cr. The oxidation resistance of NiAl was slightly improved by Ti, unaffected by Si, and degraded by Cr. The oxidation resistance of Ni3Al with 1 atomic percent Si was nearly equal to that of NiAl. Alloy B-1900 exhibited oxidation resistance comparable to that of Ni3Al + Cr compositions.

  12. CORROSION OF REFRACTORIES BY TIN AND BISMUTH

    Microsoft Academic Search

    Coultas

    1952-01-01

    Static corrosion tests were made on several refractory materials in tin ; and bismuth at 1800 deg F. The materials tested in tin, listed in decreasing ; order of resistance to attack, were: graphite, AlâOâ, Vycor, W, MoSi\\/; sub 2\\/, TaC, Kennametal K-l38A, Haynes Metaruic LT-l, Ta, and Mo. The materials ; tested in bismuth, with those most resistant to

  13. Vitreous arsenic sulfide doped with bismuth bromide

    NASA Astrophysics Data System (ADS)

    Semencha, A. V.; Kurushkin, M. V.; Markov, V. A.; Shakhmin, A. L.

    2015-05-01

    Chalcogenide glasses of the As-S-Bi-Br system are synthesized, certain physicochemical properties (density, microhardness, glass transition temperature, and transparency range) of these glasses are determined, and the refraction index is calculated based on the principle of additivity of covalent refractions. The thermally activated mobility of bismuth cations in the glass lattice and the partial transition of bismuth into a subvalent state are revealed by X-ray photoelectron spectroscopy.

  14. Electroluminescence from metal-oxide-semiconductor devices with erbium-doped CeO2 films on silicon

    NASA Astrophysics Data System (ADS)

    Lv, Chunyan; Zhu, Chen; Wang, Canxing; Gao, Yuhan; Ma, Xiangyang; Yang, Deren

    2015-04-01

    We report on erbium (Er)-related electroluminescence (EL) in the visible and near-infrared (NIR) from metal-oxide-semiconductor (MOS) devices with Er-doped CeO2 (CeO2:Er) films on silicon. The onset voltage of such EL under either forward or reverse bias is smaller than 10 V. Moreover, the EL quenching can be avoidable for the CeO2:Er-based MOS devices. Analysis on the current-voltage characteristic of the device indicates that the electron transportation at the EL-enabling voltages under either forward or reverse bias is dominated by trap-assisted tunneling mechanism. Namely, electrons in n+-Si/ITO can tunnel into the conduction band of CeO2 host via defect states at sufficiently high forward/reverse bias voltages. Then, a fraction of such electrons are accelerated by electric field to become hot electrons, which impact-excite the Er3+ ions, thus leading to characteristic emissions. It is believed that this work has laid the foundation for developing viable silicon-based emitters using CeO2:Er films.

  15. Single-electron regime and Pauli spin blockade in a silicon metal-oxide-semiconductor double quantum dot

    NASA Astrophysics Data System (ADS)

    Rochette, Sophie; Ten Eyck, Gregory A.; Pluym, Tammy; Lilly, Michael P.; Carroll, Malcolm S.; Pioro-Ladrière, Michel

    2015-03-01

    Silicon quantum dots are promising candidates for quantum information processing as spin qubits with long coherence time. We present electrical transport measurements on a silicon metal-oxide-semiconductor (MOS) double quantum dot (DQD). First, Coulomb diamonds measurements demonstrate the one-electron regime at a relatively high temperature of 1.5 K. Then, the 8 mK stability diagram shows Pauli spin blockade with a large singlet-triplet separation of approximatively 0.40 meV, pointing towards a strong lifting of the valley degeneracy. Finally, numerical simulations indicate that by integrating a micro-magnet to those devices, we could achieve fast spin rotations of the order of 30 ns. Those results are part of the recent body of work demonstrating the potential of Si MOS DQD as reliable and long-lived spin qubits that could be ultimately integrated into modern electronic facilities. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  16. A silicon nanowire-reduced graphene oxide composite as a high-performance lithium ion battery anode material.

    PubMed

    Ren, Jian-Guo; Wang, Chundong; Wu, Qi-Hui; Liu, Xiang; Yang, Yang; He, Lifang; Zhang, Wenjun

    2014-03-21

    Toward the increasing demands of portable energy storage and electric vehicle applications, silicon has been emerging as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, serious pulverization of bulk silicon during cycling limits its cycle life. Herein, we report a novel hierarchical Si nanowire (Si NW)-reduced graphene oxide (rGO) composite fabricated using a solvothermal method followed by a chemical vapor deposition process. In the composite, the uniform-sized [111]-oriented Si NWs are well dispersed on the rGO surface and in between rGO sheets. The flexible rGO enables us to maintain the structural integrity and to provide a continuous conductive network of the electrode, which results in over 100 cycles serving as an anode in half cells at a high lithium storage capacity of 2300 mA h g(-1). Due to its [111] growth direction and the large contact area with rGO, the Si NWs in the composite show substantially enhanced reaction kinetics compared with other Si NWs or Si particles. PMID:24522297

  17. Characterization of Free and Porous Silicon-Encapsulated Superparamagnetic Iron Oxide Nanoparticles as Platforms for the Development of Theranostic Vaccines

    PubMed Central

    Lundquist, Charles M.; Loo, Christopher; Meraz, Ismail M.; Cerda, Jorge De La; Liu, Xuewu; Serda, Rita E.

    2014-01-01

    Tracking vaccine components from the site of injection to their destination in lymphatic tissue, and simultaneously monitoring immune effects, sheds light on the influence of vaccine components on particle and immune cell trafficking and therapeutic efficacy. In this study, we create a hybrid particle vaccine platform comprised of porous silicon (pSi) and superparamagnetic iron oxide nanoparticles (SPIONs). The impact of nanoparticle size and mode of presentation on magnetic resonance contrast enhancement are examined. SPION-enhanced relaxivity increased as the core diameter of the nanoparticle increased, while encapsulation of SPIONs within a pSi matrix had only minor effects on T2 and no significant effect on T2* relaxation. Following intravenous injection of single and hybrid particles, there was an increase in negative contrast in the spleen, with changes in contrast being slightly greater for free compared to silicon encapsulated SPIONs. Incubation of bone marrow-derived dendritic cells (BMDC) with pSi microparticles loaded with SPIONs, SIINFEKL peptide, and lipopolysaccharide stimulated immune cell interactions and interferon gamma production in OT-1 TCR transgenic CD8+ T cells. Overall, the hybrid particle platform enabled presentation of a complex payload that was traceable, stimulated functional T cell and BMDC interactions, and resolved in cellular activation of T cells in response to a specific antigen. PMID:24932409

  18. ESR study of vacancy clusters produced by radiation damage in silicon and barium oxide. [Neutrons; gamma radiation

    SciTech Connect

    Yousif, H.N.

    1983-01-01

    The results of a study of defect cluster formation in two totally different insulating crystals; purely covalent silicon and highly ionic barium oxide are reported here. Elementary models of radiation damage in silicon relate the net defect production only to the total energy deposited in the lattice (Kinchin-Pease hypothesis). This hypothesis has been tested by monitoring electron spin resonance (ESR) signals of several dominant cluster defects, in high purity and in oxygen contaminated samples irradiated with two very different reactor spectra. The hypothesis fails. In neutron irradiated BaO crystals, a new paramagnetic defect is introduced by a sequence of annealing and gamma irradiation. It has been identified as belonging to adjacent barium and oxygen vacancies with a single trapped electron. Analysis of the hyperfine interactions with the five near neighbor bariums gives rise to a detailed interpretation of the electron wave function as that of a weakly perturbed F/sup +/ center in the electric field of the barium vacancy. A defect model is proposed to account for the hyperfine interactions. The defect is shown to be formed by thermally activated migration of the barium vacancy, with an activation energy of 1.26 +/- 0.15 eV.

  19. Morphology of a blend of zinc neutralized sulfonated poly(phenylene oxide) or polystyrene and an amino silicone

    SciTech Connect

    Jones, A.A.; Inglefield, P.T.; Zhang, Changlai; Bergquist, P [Clark Univ., Worcester, MA (United States). Dept. of Chemistry] [and others

    1996-12-31

    A polymer blend of an ionomer based on zinc neutralized sulfonated poly(phenylene oxide) or polystyrene with a silicone copolymer containing 6.45% propylamine groups in place of one of the methyl groups on a backbone silicon was prepared. Carbon-13 magic angle spinning spectra show coordination of the amine, by the zinc ions. Morphological characterization was made by NMR spectroscopy based on proton spin diffusion, by small angle x-ray scattering and by energy filtered transmission electron microscopy. All experiments show domains in the range of 1 to 1000 nm and domain size can be controlled by the extent of coordination of the amine groups by the zinc ions and by thermal history. The different lead to an apparent hierarchy of domain sizes. The NMR domains, 2 to 10 nm, where contrast is produced by differences in chain mobility. Small angle x-ray scattering indicates domains of 16 nm while electron in the range of 100 to 1000 nm. The variation of the domain size between experiments may reflect the different sources of contrast in each cam.

  20. Quantitative Real-Time Measurements of DNA Hybridization with Alkylated Non-Oxidized Silicon Nanowires in Electrolyte Solution

    PubMed Central

    Bunimovich, Yuri L.; Shin, Young Shik; Yeo, Woon-Seok; Amori, Michael; Kwong, Gabriel

    2013-01-01

    The quantitative, real time detection of single stranded oligonucleotides with silicon nanowires (SiNWs) in physiologically relevant electrolyte solution is demonstrated. Debye screening of the hybridization event is minimized by utilizing electrostatically adsorbed primary DNA on an amine-terminated NW surface. Two surface functionalization chemistries are compared: an amine terminated siloxane monolayer on the native SiO2 surface of the SiNW, and an amine terminated alkyl monolayer grown directly on a hydrogen-terminated SiNW surface. The SiNWs without the native oxide exhibit improved solution-gated field-effect transistor characteristics and a significantly enhanced sensitivity to single stranded DNA detection, with an accompanying two orders of magnitude improvement in the dynamic range of sensing. A model for the detection of analyte by SiNW sensors is developed and utilized to extract DNA binding kinetic parameters. Those values are directly compared with values obtained by the standard method of surface plasmon resonance (SPR), and demonstrated to be similar. The nanowires, however, are characterized by higher detection sensitivity. The implication is that Si NWs can be utilized to quantitate the solution phase concentration of biomolecules at low concentrations. This work also demonstrates the importance of surface chemistry for optimizing biomolecular sensing with silicon nanowires. PMID:17165787

  1. Corrosion behavior of plasma sprayed hydroxyapatite and hydroxyapatite-silicon oxide coatings on AISI 304 for biomedical application

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Singh, Hazoor; Sidhu, Buta Singh

    2013-11-01

    The objective of this study is to evaluate corrosion resistance of plasma sprayed hydroxyapatite (HA) and HAsbnd silicon oxide (SiO2) coated AISI 304 substrates. In HAsbnd SiO2 coatings, 10 wt% SiO2 and 20 wt% SiO2 was mixed with HA. The feedstock and coatings were characterized by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy. The corrosion resistance was determined for the uncoated and coated samples. The corrosion resistance of the AISI 304 was found more after the deposition of the HAsbnd SiO2 coatings rather than HA coating and uncoated. All the coatings were crack free after 24 h dipping in Ringer's solution for electrochemical corrosion testing.

  2. Enhanced telecom wavelength single-photon detection with NbTiN superconducting nanowires on oxidized silicon

    NASA Astrophysics Data System (ADS)

    Tanner, M. G.; Natarajan, C. M.; Pottapenjara, V. K.; O'Connor, J. A.; Warburton, R. J.; Hadfield, R. H.; Baek, B.; Nam, S.; Dorenbos, S. N.; Ureña, E. Bermúdez; Zijlstra, T.; Klapwijk, T. M.; Zwiller, V.

    2010-05-01

    Superconducting nanowire single-photon detectors (SNSPDs) have emerged as a highly promising infrared single-photon detector technology. Next-generation devices are being developed with enhanced detection efficiency (DE) at key technological wavelengths via the use of optical cavities. Furthermore, new materials and substrates are being explored for improved fabrication versatility, higher DE, and lower dark counts. We report on the practical performance of packaged NbTiN SNSPDs fabricated on oxidized silicon substrates in the wavelength range from 830 to 1700 nm. We exploit constructive interference from the SiO2/Si interface in order to achieve enhanced front-side fiber-coupled DE of 23.2 % at 1310 nm, at 1 kHz dark count rate, with 60 ps full width half maximum timing jitter.

  3. Low-power embedded read-only memory using atom switch and silicon-on-thin-buried-oxide transistor

    NASA Astrophysics Data System (ADS)

    Sakamoto, Toshitsugu; Tada, Munehiro; Tsuji, Yukihide; Makiyama, Hideki; Hasegawa, Takumi; Yamamoto, Yoshiki; Okanishi, Shinobu; Banno, Naoki; Miyamura, Makoto; Okamoto, Koichiro; Iguchi, Noriyuki; Ogasahara, Yasuhiro; Oda, Hidekazu; Kamohara, Shiro; Yamagata, Yasushi; Sugii, Nobuyuki; Hada, Hiromitsu

    2015-04-01

    We developed an atom-switch read-only memory (ROM) fabricated on silicon-on-thin-buried-oxide (SOTB) for use in a low-power microcontroller for the first time. An atom switch with a low programming voltage and large ON/OFF conductance ratio is suitable for low-power nonvolatile memory. The atom-switch ROM using an SOTB transistor uses a 0.34–1.2 V operating voltage and 12 µA/MHz active current (or 4.5 µW/MHz active power). Furthermore, the sleep current is as low as 0.4 µA when a body bias voltage is applied to the SOTB.

  4. Energy transfer from luminescent centers to Er3+ in erbium-doped silicon-rich oxide films

    PubMed Central

    2013-01-01

    The energy transfer mechanism between luminescent centers (LCs) and Er3+ in erbium-doped silicon-rich oxide (SROEr) films prepared by electron beam evaporation is investigated. Intense photoluminescence of the LCs (weak oxygen bonds, neutral oxygen vacancies, and Si=O states) within the active matrixes is obtained. Fast energy transfer from Si=O states to Er3+ takes advantage in the SROEr film and enhances the light emission from Er3+. The introduction of Si nanoclusters, which induces the Si=O states and facilitates the photon absorption of the Si=O states, is essential to obtain intense photoluminescence from both Si=O states and Er3+. PMID:23981444

  5. Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide-semiconductor-compatible silicon nanowires

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Jun; Agarwal, Ajay; Buddharaju, Kavitha D.; Singh, Navab; Gao, Zhiqiang

    2007-06-01

    Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide- semiconductor-compatible silicon nanowires (SiNWs) with crown ethers covalently immobilized on their surface are presented. A densely packed organic monolayer terminated with amine groups is introduced to the SiNW surface via hydrosilylation. Amine-modified crown ethers, acting as sensing elements, are then immobilized onto the SiNWs through a cross-linking reaction with the monolayer. The crown ether-functionalized SiNWs recognize Na+ and K+ according to their complexation ability to the crown ethers. The SiNW sensors are highly selective and capable of achieving an ultralow detection limit down to 50nM, over three orders of magnitude lower than that of conventional crown ether-based ion-selective electrodes.

  6. Correlation of the structural and optical properties of luminescent, highly oxidized porous silicon

    Microsoft Academic Search

    A. G. Cullis; L. T. Canham; G. M. Williams; P. W. Smith; O. D. Dosser

    1994-01-01

    The light-emitting properties of rapid thermally oxidized porous Si are studied by both photoluminescence and cathodoluminescence methods. The structure of the material is examined by transmission electron microscopy, while its oxygen content is determined by x-ray microanalysis. These investigations show that crystalline Si nanostructures remain in the heavily oxidized porous material and account for its ?750 nm red photo- and

  7. The Effect of Silicon and Aluminum Additions on the Oxidation Resistance of Lean Chromium Stainless Steels

    SciTech Connect

    Dunning, J.S.; Alman, D.E.; Rawers, J.C.

    2001-09-01

    The effect of Si and Al additions on the oxidation of lean chromium austenitic stainless steels has been studied. A baseline composition of Fe-16Cr-16Ni-2Mn-1Mo was selected to allow combined Si and Al additions of up to 5 wt. pct. in a fully austenitic alloy. The baseline composition was selected using a net Cr equivalent equation to predict the onset of G-ferrite formation in austenite. Cyclic oxidation tests in air for 1000 hours were carried out on alloys with Si only or combined Si and Al additions in the temperature range 700 C to 800 C. Oxidation resistance of alloys with Si only additions were outstanding, particularly at 800 C. It was evident that different rate controlling mechanisms for oxidation were operative at 700 C and 800 C in the Si alloys. In addition, Si alloys pre-oxidized at 800 C, showed a zero weight gain in subsequent testing for 1000 hours at 700 C. The rate controlling mechanism in alloys with combined Si and Al addition for oxidation at 800 C was also different than alloys with Si only. SEM and ESCA analysis of the oxide films and base material at the oxide/base metal interface were conducted to study potential rate controlling mechanisms.

  8. Active silicon octagonal micropillar resonator modulators using metal-oxide-semiconductor capacitors

    E-print Network

    Poon, Andrew Wing On

    -oxide-semiconductor capacitors Chao Li and Andrew W. Poon Department of Electrical and Electronic Engineering, The Hong Kong resonator modulators using metal-oxide-semiconductor capacitors. Our initial electrical and optical simulations suggest a high-extinction ratio resonance modulation by selectively embedding capacitors along

  9. Infrared surface polaritons on bismuth

    NASA Astrophysics Data System (ADS)

    Khalilzadeh-Rezaie, Farnood; Smith, Christian W.; Nath, Janardan; Nader, Nima; Shahzad, Monas; Cleary, Justin W.; Avrutsky, Ivan; Peale, Robert E.

    2015-01-01

    Optical constants for evaporated bismuth (Bi) films were measured by ellipsometry and compared with those published for single crystal and melt-cast polycrystalline Bi in the wavelength range of 1 to 40 ?m. The bulk plasma frequency ?p and high-frequency limit to the permittivity ?? were determined from the long-wave portion of the permittivity spectrum, taking previously published values for the relaxation time ? and effective mass m*. This part of the complex permittivity spectrum was confirmed by comparing calculated and measured reflectivity spectra in the far-infrared. Properties of surface polaritons (SPs) in the long-wave infrared were calculated to evaluate the potential of Bi for applications in infrared plasmonics. Measured excitation resonances for SPs on Bi lamellar gratings agree well with calculated resonance spectra based on grating geometry and complex permittivity.

  10. Evaluation of bismuth germanate detectors

    SciTech Connect

    Swinth, K.L.; Eschbach, P.A.

    1993-12-01

    During International Atomic Energy Agency (IAEA) safeguards inspections, one of the activities is the verification of materials in the inventory through quantitative or qualitative measurements. Performance of these measurements requires an array of sophisticated detectors, electronics, shields, and stands. This requires the transport and handling of delicate systems that are both heavy and bulky. The increasing sophistication and miniaturization of electronic and computer systems have led to progressive reductions in both the weight and the bulk of such electronics. However, to take full advantage of these improvements, similar reductions must also occur in the size and weight of the detectors. The purpose of this study was to explore the usefulness of one type of new detector, the bismuth germinate (BGO) scintillator. The purpose was to test detectors for their performance at high (fission products) and low ({sup 235}U) photon energies. Information is also provided on other scintillators, including those using photodiode-coupled cesium iodide and germanium orthosilicate.

  11. Studies on Nanocrystalline Bismuth Telluride

    SciTech Connect

    Ghatak, Amitava [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Assam-781039 (India)

    2010-10-04

    Nanostructured thermoelectric bismuth telluride powders with various hydrothermal synthesis times were synthesised to give an experimental comprehension on the formation of the nanopowders. Nanoparticles were synthesised at 130 deg. C for 24 h and 72 h. Bi{sub 2}Te{sub 3} nanoparticles with grain sizes 120A and 170A exhibit n-type semiconducting behaviour with a decrease in Seebeck coefficient with increasing temperature range. The activation energy ({Delta}E{sub S}) calculated from S vs. 1000/T graphs decreases with increasing synthesis time. This variation in {Delta}E{sub S} with synthesis time of the Bi{sub 2}Te{sub 3} nanomaterial may be due to the small amount unreacted carrier content in the material.

  12. Hydrogen-terminated silicon nanowire photocatalysis: Benzene oxidation and methyl red decomposition

    SciTech Connect

    Lian, Suoyuan [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); School of Chemical Engineering and Materials, Dalian Polytechnic University, Dalian 116034 (China); Tsang, Chi Him A. [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)] [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)] [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Wong, Ningbew [Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China)] [Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Lee, Shuit-Tong [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China)

    2011-12-15

    Graphical abstract: H-SiNWs can catalyze hydroxylation of benzene and degradation of methyl red under visible light irradiation. Highlights: Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were active photocatalyst in the hydroxylation of benzene under light. Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were also effective in the decomposition of methyl red dye. Black-Right-Pointing-Pointer The Si/SiO{sub x} core-shell structure is the main reason of the obtained high selectivity during the hydroxylation. -- Abstract: Hydrogen-terminated silicon nanowires (H-SiNWs) were used as heterogeneous photocatalysts for the hydroxylation of benzene and for the decomposition of methyl red under visible light irradiation. The above reactions were monitored by GC-MS and UV-Vis spectrophotometry, respectively, which shows 100% selectivity for the transformation of benzene to phenol. A complete decomposition of a 2 Multiplication-Sign 10{sup -4} M methyl red solution was achieved within 30 min. The high selectivity for the hydroxylation of benzene and the photodecomposition demonstrate the catalytic activity of ultrafine H-SiNWs during nanocatalysis.

  13. Reactions of silicon-based ceramics in mixed oxidation chlorination environments

    NASA Technical Reports Server (NTRS)

    Marra, John E.; Kreidler, Eric R.; Jacobson, Nathan S.; Fox, Dennis S.

    1988-01-01

    The reaction of silicon-based ceramics with 2 percent Cl2/Ar and 1 percent Cl2/1 percent to 20 percent O2/Ar at 950 C was studied with thermogravimetric analysis and high-pressure mass spectrometry. Pure Si, SiO2, several types of SiC, and Si3N4 were examined. The primary corrosion products were SiCl4(g) and SiO2(s) with smaller amounts of volatile silicon oxychlorides. The reactions appear to occur by chlorine penetration of the SiO2 layer, and gas-phase diffusion of the silicon chlorides away from the sample appears to be rate limiting. Pure SiO2 shows very little reaction with Cl2, SiC with excess Si is more reactive than the other materials with Cl2, whereas SiC with excess carbon is more reactive than the other materials with Cl2/O2. Si3N4 shows very little reaction with Cl2. These differences are explained on the basis of thermodynamic and microstructural factors.

  14. Fatigue failure in thin-film polycrystalline silicon is due to subcritical cracking within the oxide layer

    E-print Network

    Ritchie, Robert

    Fatigue failure in thin-film polycrystalline silicon is due to subcritical cracking within polycrystalline silicon thin films are subject to cyclic fatigue. Prior work by the authors has suggested that although bulk silicon is not susceptible to fatigue failure in ambient air, fatigue in micron-scale silicon

  15. Effect of W and WC on the oxidation resistance of yttria-doped silicon nitride

    NASA Technical Reports Server (NTRS)

    Schuon, S.

    1980-01-01

    The effect of W and WC contamination on the oxidation and cracking in air of sintered Si3N4 - 8 w/o Y2O3 ceramics at 500, 750, and 1350 C is examined. A mixture of Si3N4 - 8Y2O3, milled with alumina balls, was divided into four portions. Three portions were doped with 2 w/o WC W, and 4 w/o W respectively, in order to simulate contamination during milling. The fourth portion was undoped and used on a control. The addition of W or WC did not affect the phase relationships in the system, as all bars with or without additions contained melilite as the major Si-Y-O-N phase after sintering. At 750 C, instability (rapid oxidation and cracking) of W-doped bars appears to have occurred as a result of oxidation of the tungsten containing melilite phase. No intermediate temperature instability was observed in bars containing 2 w/o WC or in bars with no additive. Specimens exposed at 1350 C had good oxidation resistance due to the formation of a protective siliceous oxide layer. A specimen containing 4 w/o W which was preoxidized at 1350 C had improved oxidation resistance at 750 C. The tendency towards oxidation and cracking of Si3N4 - 8 Y2O3 at 750 C is concluded to be related to tungsten content of the sintered bars.

  16. Tamao-Fleming Oxidations in Organic Synthesis: Carbon-Silicon Bonds as Functional Group Masks

    E-print Network

    Stoltz, Brian M.

    Tamao Oxidations can be carried out under a variety of pH's when H2O2 is the oxidant Acidic Conditions: R SiLn 30% H2O2, Ac2O, KHF2 DMF, r.t. R OH Neutral Conditions: 30% H2O2, KHF2 DMF, r.t. to 60°CR SiLn R OH Basic: R SiLn R OH30% H2O2 , KHCO3 MeOH / THF, 60°C -mCPBA is also a commonly employed oxidant

  17. Electrodeposition of molten silicon

    DOEpatents

    De Mattei, Robert C. (Sunnyvale, CA); Elwell, Dennis (Palo Alto, CA); Feigelson, Robert S. (Saratoga, CA)

    1981-01-01

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

  18. Critical Oxide Thickness for Efficient Single-walled Carbon Nanotube Growth on Silicon Using Thin SiO2 Diffusion Barriers

    Microsoft Academic Search

    J. M. Simmons; Beth M. Nichols; Matthew S. Marcus; O. M. Castellini; R. J. Hamers; M. A. Eriksson

    2007-01-01

    The ability to integrate carbon nanotubes, especially single-walled carbon\\u000ananotubes, seamlessly onto silicon would expand the range of applications\\u000aconsiderably. Though direct integration using chemical vapor deposition is the\\u000asimplest method, the growth of single-walled carbon nanotubes on bare silicon\\u000aand on ultra-thin oxides is greatly inhibited due to the formation of a\\u000anon-catalytic silicide. Using x-ray photoelectron spectroscopy, we

  19. Effect of target temperature on the reactive d.c.sputtering of silicon and niobium oxides

    Microsoft Academic Search

    Raymond Y. Chau; W-S Ho; J. C. Wolfe; Darian L. Licon

    1996-01-01

    We study the deposition of Si and Nb oxides by reactive d.c.-magnetron sputtering from high temperature metallic Si and Nb targets in Ar\\/O2 atmospheres. It is shown that the oxidess formed on Si targets above 1 500 K and on Nb above 2 310 K evaporate, leaving the target surface free of the solid oxide coatings which induce hysteresis, voltage

  20. Oxygen defects and Fermi level location in metal-hafnium oxide-silicon structures

    Microsoft Academic Search

    Daeyoung Lim; Richard Haight; Matthew Copel; Eduard Cartier

    2005-01-01

    We describe an in situ method for measuring the band bending of Si substrates in complex metal-oxide-semiconductor systems using femtosecond pump-probe photoelectron spectroscopy. Following deposition of metal layers (Pt, Re, or Re oxide) on the high-k dielectric HfO2, measurement of the band bending in the underlying Si provides a direct determination of the location of the Fermi level within the

  1. Enhanced lifetime in porous silicon light-emitting diodes with fluorine doped tin oxide electrodes

    Microsoft Academic Search

    Andréia G. Macedo; Elder A. de Vasconcelos; Rogério Valaski; Fábio Muchenski; Eronides F. da Silva; Antônio F. da Silva; Lucimara S. Roman

    2008-01-01

    We investigated the electrical and optical properties of porous Si (PS) light-emitting diodes using fluorinated tin oxide (FTO) as transparent electrodes. At high forward bias, the current–voltage characteristic is space charge limited. At low forward bias, it follows an exponential law. Whereas the electroluminescence (EL) in devices with non-fluorinated indium–tin oxide electrodes degrades in few minutes, EL intensity in devices

  2. Silicon nanocrystals based light emitting diodes integrated using all inorganic metal oxides as the charge transport layers

    NASA Astrophysics Data System (ADS)

    Cheng, A.-J.; Liptak, R. W.; Kortshagen, U.; Campbell, S. A.

    2010-02-01

    Air-stable luminescence silicon nanocrystals (Si-NCs) were synthesized using a novel in-flight system composed of a Si-NC synthesis SiH4/Ar plasma and an SF6 plasma which etches and passivates the NCs. The etch plasma can efficiently tailor the Si-NC size and the surface functionalities by tuning the gas flow rate, applied power, and pressure of the plasma. Si-NCs based light emitting diodes (LEDs) were fabricated by using the Si-NCs as the recombination center for injected electron-hole pairs. Si-NCs were deposited in between two inorganic metal oxide layers, nickel oxide (NiO) and zinc oxide (ZnO), which served as the hole transport layer (HTL) and electron transport layer (ETL), respectively. NiO and ZnO have been chosen by considering their energy band offsets with respect to Si-NCs, and their band offsets to the electrodes which should produce roughly comparable carrier concentrations once the contacts are forward biased, to get charge balance at the Si-NCs. The as-prepared metal oxides were confirmed to be stoichiometric using Auger Electron Spectroscopy (AES). Four-point probes measurements show the oxide sheet resistances in the range of 2-5×106 ?/(see manuscript). The as-prepared etched Si-NCs generate orange photoluminescence at a peak intensity of 650nm with a quantum efficiency of 23%. I-V characteristics and light intensities of the Si-NCs LED without depositing the ZnO ETL have been studied with respected to the Si-NCs thickness. LEDs made using a two minute deposition of Si-NCs (approximately 250nm thick) showed an easily visible air-stable light emission; however, the light intensity decreased by 50% for thicker (1.5?m) Si-NC films. The LED performance was improved by using an ITO/ZnO/SiNCs/NiO/Al device structure. The turned on voltage increased to 7V but the current saturated to 0.1A very rapidly. The Si-NCs LED EL spectrum was collected at a bias voltage of 8.5V. The emission peaked at 653 nm for the Si-NCs LED in good agreement with the PL results. At the highest current densities some degradation of the device was observed, otherwise device operation was consistent and yield was good. The I-V characteristics of the Si-NC LED made using all inorganic metal oxides showed Schottky behavior as well as good light intensity.

  3. Bismuth alloy potting seals aluminum connector in cryogenic application

    NASA Technical Reports Server (NTRS)

    Flower, J. F.; Stafford, R. L.

    1966-01-01

    Bismuth alloy potting seals feedthrough electrical connector for instrumentation within a pressurized vessel filled with cryogenic liquids. The seal combines the transformation of high-bismuth content alloys with the thermal contraction of an external aluminum tube.

  4. Bismuth nanowire and antidot array studies motivated by thermoelectricity

    E-print Network

    Rabin, Oded, 1974-

    2004-01-01

    Porous anodic alumina (PAA) films were utilized to template the fabrication of nanostructures of bismuth, antimony and bismuth-antimony alloys. The cylindrical template pores were used to synthesize nanowires by electrochemical ...

  5. Topological nature and the multiple Dirac cones hidden in Bismuth high-Tc superconductors

    PubMed Central

    Li, Gang; Yan, Binghai; Thomale, Ronny; Hanke, Werner

    2015-01-01

    Recent theoretical studies employing density-functional theory have predicted BaBiO3 (when doped with electrons) and YBiO3 to become a topological insulator (TI) with a large topological gap (~0.7?eV). This, together with the natural stability against surface oxidation, makes the Bismuth-Oxide family of special interest for possible applications in quantum information and spintronics. The central question, we study here, is whether the hole-doped Bismuth Oxides, i.e. Ba1-xKxBiO3 and BaPb1-xBixO3, which are “high-Tc” bulk superconducting near 30?K, additionally display in the further vicinity of their Fermi energy EF a topological gap with a Dirac-type of topological surface state. Our electronic structure calculations predict the K-doped family to emerge as a TI, with a topological gap above EF. Thus, these compounds can become superconductors with hole-doping and potential TIs with additional electron doping. Furthermore, we predict the Bismuth-Oxide family to contain an additional Dirac cone below EF for further hole doping, which manifests these systems to be candidates for both electron- and hole-doped topological insulators. PMID:26014056

  6. Topological nature and the multiple Dirac cones hidden in Bismuth high-Tc superconductors.

    PubMed

    Li, Gang; Yan, Binghai; Thomale, Ronny; Hanke, Werner

    2015-01-01

    Recent theoretical studies employing density-functional theory have predicted BaBiO3 (when doped with electrons) and YBiO3 to become a topological insulator (TI) with a large topological gap (~0.7?eV). This, together with the natural stability against surface oxidation, makes the Bismuth-Oxide family of special interest for possible applications in quantum information and spintronics. The central question, we study here, is whether the hole-doped Bismuth Oxides, i.e. Ba1-xKxBiO3 and BaPb1-xBixO3, which are "high-Tc" bulk superconducting near 30?K, additionally display in the further vicinity of their Fermi energy EF a topological gap with a Dirac-type of topological surface state. Our electronic structure calculations predict the K-doped family to emerge as a TI, with a topological gap above EF. Thus, these compounds can become superconductors with hole-doping and potential TIs with additional electron doping. Furthermore, we predict the Bismuth-Oxide family to contain an additional Dirac cone below EF for further hole doping, which manifests these systems to be candidates for both electron- and hole-doped topological insulators. PMID:26014056

  7. Metal oxide/silicon heterostructures: New solutions for different optoelectronic applications

    SciTech Connect

    Malik, A.; Martins, R. [FCT-UNL/CEMOP-UNINOVA, Monte de Caparica (Portugal)

    1998-12-31

    In this paper the authors report the success in fabricating FTO/Si surface-barrier photodiodes production by spray pyrolysis deposition technique, under ambient conditions. Three types of photodetectors for low-voltage-bias operation were developed based on high-resistivity silicon: (1) X-ray detectors with energy resolution of 16.5% at 661.5 keV ({sup 137}Cs source), consisting of surface-barrier PIN photodiode with an active area of 50 mm{sup 2} operating at 5V reverse bias, scintillator based on monocrystalline Bi{sub 4}Ge{sub 3}O{sub 12} and preamplifier (noise of 250 e{sup {minus}} RMS); (2) fast-response surface-barrier FTO/n{sup {minus}}-n{sup +} silicon epitaxial photodiodes, operating at 10 V bias with rise times of 2 ns at {lambda} = 0.85 {micro}m; (3) radiation-resistant drift epitaxial surface-barrier PIN photodiodes for unbiased operating conditions, with an exponential impurity distribution in a 8 {micro}m thick epitaxial layer. A built-in electrical field due to the carrier concentration distribution in the epitaxial layer provides a considerable improvement in the critical fluence value (3 {times} 10{sup 14} cm{sup {minus}2}) for neutron irradiation.

  8. Strain-induced transformation of amorphous spherical precipitates into platelets: Application to oxide particles in silicon

    SciTech Connect

    Voronkov, V. V.; Falster, R.

    2001-06-01

    The spherical shape of an amorphous precipitate becomes unstable if the combination P{sup 2}R of precipitate radius R and pressure P exceeds some critical value. This critical value was found to be about 4.44 G{sigma}, where G is the matrix shear modulus and {sigma} is the specific energy of the precipitate/matrix interface. Once this instability criterion is fulfilled, the initially spherical particle will reduce the total free energy (the sum of strain energy and the surface energy) by becoming a thin oblate spheroid (effectively, a platelet). The actual pressure P in the course of oxygen precipitation in silicon is controlled by a high self-interstitial supersaturation caused by emission of self-interstitials by growing precipitates. The duration of annealing necessary to reach the stage of collapse of spheres into platelets is calculated as a function of temperature and the precipitate density. Calculated results are compatible with the experimentally observed annealing conditions for platelet formation. Another important example of sphere to platelet transformation is microdefect formation in vacancy-type silicon. In this case a large negative value of P is sufficient to induce collapse. {copyright} 2001 American Institute of Physics.

  9. Bell Labs - Physical Sciences - Silicon Processing Introduction

    NSDL National Science Digital Library

    This website includes a description of silicon processing from Bell Laboratories. Silicon chips are prepared by an elaborate sequence of processing steps applied to a silicon wafer. Keywords: Patterning, implantation, oxidation, metallization, photoresist

  10. Lead-Bismuth Spallation Target Design Yousry Gohar

    E-print Network

    McDonald, Kirk

    Lead-Bismuth Spallation Target Design Yousry Gohar Nuclear Engineering Division Argonne National Driven System #12;Lead-Bismuth Spallation Target Design A study was carried out to analyze and design a Lead-Bismuth spallation target for driving a subcritical assembly. Performance Parameters: Produce

  11. Process for producing silicon

    DOEpatents

    Olson, Jerry M. (Lakewood, CO); Carleton, Karen L. (Boulder, CO)

    1984-01-01

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

  12. Hybridization effects and bond disproportionation in the bismuth perovskites

    NASA Astrophysics Data System (ADS)

    Foyevtsova, Kateryna; Khazraie, Arash; Elfimov, Ilya; Sawatzky, George A.

    2015-03-01

    We propose a microscopic description of the bond-disproportionated insulating state in the bismuth perovskites X BiO3 (X =Ba,Sr ) that recognizes the bismuth-oxygen hybridization as a dominant energy scale. It is demonstrated by using electronic structure methods that the breathing distortion is accompanied by spatial condensation of hole pairs into local, molecularlike orbitals of the A1 g symmetry composed of O-2 p? and Bi-6 s atomic orbitals of collapsed BiO6 octahedra. The primary importance of oxygen p states is thus revealed, in contrast to a popular picture of a purely ionic Bi3 +/Bi5 + charge disproportionation. Octahedra tilting is shown to enhance the breathing instability by means of a nonuniform band narrowing. We argue that the formation of localized states upon breathing distortion is, to a large extent, a property of the oxygen sublattice, and we expect similar hybridization effects in other perovskites involving formally high oxidation state cations.

  13. Silicon nanowires with high-k hafnium oxide dielectrics for sensitive detection of small nucleic acid oligomers.

    PubMed

    Dorvel, Brian R; Reddy, Bobby; Go, Jonghyun; Duarte Guevara, Carlos; Salm, Eric; Alam, Muhammad Ashraful; Bashir, Rashid

    2012-07-24

    Nanobiosensors based on silicon nanowire field effect transistors offer advantages of low cost, label-free detection, and potential for massive parallelization. As a result, these sensors have often been suggested as an attractive option for applications in point-of-care (POC) medical diagnostics. Unfortunately, a number of performance issues, such as gate leakage and current instability due to fluid contact, have prevented widespread adoption of the technology for routine use. High-k dielectrics, such as hafnium oxide (HfO(2)), have the known ability to address these challenges by passivating the exposed surfaces against destabilizing concerns of ion transport. With these fundamental stability issues addressed, a promising target for POC diagnostics and SiNWFETs has been small oligonucleotides, more specifically, microRNA (miRNA). MicroRNAs are small RNA oligonucleotides which bind to mRNAs, causing translational repression of proteins, gene silencing, and expressions are typically altered in several forms of cancer. In this paper, we describe a process for fabricating stable HfO(2) dielectric-based silicon nanowires for biosensing applications. Here we demonstrate sensing of single-stranded DNA analogues to their microRNA cousins using miR-10b and miR-21 as templates, both known to be upregulated in breast cancer. We characterize the effect of surface functionalization on device performance using the miR-10b DNA analogue as the target sequence and different molecular weight poly-l-lysine as the functionalization layer. By optimizing the surface functionalization and fabrication protocol, we were able to achieve <100 fM detection levels of the miR-10b DNA analogue, with a theoretical limit of detection of 1 fM. Moreover, the noncomplementary DNA target strand, based on miR-21, showed very little response, indicating a highly sensitive and highly selective biosensing platform. PMID:22695179

  14. The study of tribological performance and surface film characterization of bismuth dioctyldithiocarbamate

    SciTech Connect

    Chen Ligong; Dong Junxiu; Chen Guoxu [Logistical Engineering Coll., Chongqing (China)

    1997-05-01

    In this study, bismuth dioctyldithiocarbamate has been synthesized, and its tribological behaviors, such as friction-reducing ability, antiwear property and extreme pressure performance have been respectively evaluated with a ring-on-block test rig and a fourball machine. In addition to correlate its tribological behaviors with the film formed on the metallic rubbing surface under boundary lubrication conditions, surface analyses have been conducted to characterize the surface film by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and energy dispersion of X-ray (EDX). Test results show the additive compound can effectively improve the friction and wear of the rubbing couples. On the other hand, EDX confirmed the presence of carbon, oxygen, sulfur, nitrogen, bismuth and iron on the surface; AES revealed their depth distribution of atomic concentration percentages. Whereas XPS further disclosed that the composition of the surface film was composed of organic and inorganic species including iron sulfide and sulfate, metallic bismuth, bismuth oxide and sulfide, etc. which are conducive to the reduction of friction and wear.

  15. Determination of trace amounts of lead and cadmium using a bismuth/glassy carbon composite electrode.

    PubMed

    Hwang, Gil-Ho; Han, Won-Kyu; Hong, Seok-Jun; Park, Joon-Shik; Kang, Sung-Goon

    2009-02-15

    We examined the use of a bismuth-glassy carbon (Bi/C) composite electrode for the determination of trace amounts of lead and cadmium. Incorporated bismuth powder in the composite electrode was electrochemically dissolved in 0.1M acetate buffer (pH 4.5) where nanosized bismuth particles were deposited on the glassy carbon at the reduction potential. The anodic stripping voltammetry on the Bi/C composite electrode exhibited well-defined, sharp and undistorted peaks with a favorable resolution for lead and cadmium. Comparing a non-oxidized Bi/C composite electrode with an in-situ plated bismuth film electrode, the Bi/C composite electrode exhibited superior performance due to its much larger surface area. The limit of detection was 0.41 microg/L for lead and 0.49 microg/L for cadmium. Based on this study, we are able to conclude that various types of composite electrodes for electroanalytical applications can be developed with a prudent combination of electrode materials. PMID:19084661

  16. Laser-Surface Alloying of Nimonic 80 with Silicon and Aluminum and its Oxidation Behavior

    NASA Astrophysics Data System (ADS)

    Majumdar, Jyotsna Dutta; Manna, Indranil

    2012-10-01

    In the current study, laser-surface alloying (LSA) of Nimonic 80 (a Ni-based superalloy) was conducted using a high-power continuous wave (CW) CO2 laser by simultaneous feeding of predetermined proportion of elemental Si and Al powders with an Ar shroud. After LSA, the microstructure of the alloyed zone was carefully analyzed and found to consist of several intermetallic phases of Ni and Si. The microhardness of the alloyed zone was significantly increased to 500 VHN compared with 250 VHN of the as-received substrate. The high-temperature oxidation resistance of the laser-surface-alloyed specimens (under isothermal conditions) was improved (at temperature ranges between 1223 K and 1423 K [950 °C and 1150 °C]) compared with as-received Nimonic. Even though LSA enhanced resistance to oxidation up to a limited period, continued exposure to extended hours (at a given temperature) led to spallation of scale. It seems that a SiO2-rich adherent scale is responsible for enhanced protection against oxidation in the laser-surface-alloyed specimens. However, the presence of Al2O3 in the oxide film enhances the resistance to spallation by increasing the scale adherence at a higher temperature. The results are supported by a suitable thermodynamic calculation.

  17. Formation of silicon oxide nanowires in nanomaterial synthesis experiments based on the usage of tube furnace

    NASA Astrophysics Data System (ADS)

    Li, Chunfei; Solomon, Virgil; Moro, Marjan; Welsh, Chad; McCauley, Tyler; Bauer, Michael; Cupo, Joseph

    2013-08-01

    In an effort to synthesize doped ZnO nanowires, SiO x nanowires were obtained accidently. In the experiment, mixed powders containing chemicals such as ZnO, graphite, Ga2O3, and In2O3 were placed in the center of a tube furnace, where the temperature was set to 1200 °C and the vacuum was approximately 27 Pa. Silicon wafers were placed around the vicinity of the furnace exit to collect the expected nanomaterials. After prolonged heating, grey layers were found on top of one wafer located inside the furnace. The layer showed no adhesion to the substrate. Characterization by using Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and Energy Dispersive X-ray Spectroscopy (EDS) revealed that this layer consisted of SiO x nanowires. Formation of Si-containing liquid drop and the subsequent growth of SiO x nanowires out of it are suggested as the growth mechanism.

  18. Non-oxidized porous silicon-based power AC switch peripheries

    PubMed Central

    2012-01-01

    We present in this paper a novel application of porous silicon (PS) for low-power alternating current (AC) switches such as triode alternating current devices (TRIACs) frequently used to control small appliances (fridge, vacuum cleaner, washing machine, coffee makers, etc.). More precisely, it seems possible to benefit from the PS electrical insulation properties to ensure the OFF state of the device. Based on the technological aspects of the most commonly used AC switch peripheries physically responsible of the TRIAC blocking performances (leakage current and breakdown voltage), we suggest to isolate upper and lower junctions through the addition of a PS layer anodically etched from existing AC switch diffusion profiles. Then, we comment the voltage capability of practical samples emanating from the proposed architecture. Thanks to the characterization results of simple Al-PS-Si(P) structures, the experimental observations are interpreted, thus opening new outlooks in the field of AC switch peripheries. PMID:23057856

  19. Strengthening of oxidation resistant materials for gas turbine applications. [treatment of silicon ceramics for increased flexural strength and impact resistance

    NASA Technical Reports Server (NTRS)

    Kirchner, H. P.

    1974-01-01

    Silicon nitride and silicon carbide ceramics were treated to form compressive surface layers. On the silicon carbide, quenching and thermal exposure treatments were used, and on the silicon nitride, quenching, carburizing, and a combination of quenching and carburizing were used. In some cases substantial improvements in impact resistance and/or flexural strength were observed. The presence of compressive surface stresses was demonstrated by slotted rod tests.

  20. Effect of acidic pretreatment combined with a silane coupling agent on bonding durability to silicon oxide ceramic.

    PubMed

    Foxton, Richard M; Nakajima, Masatoshi; Tagami, Junji; Miura, Hiroyuki

    2005-04-01

    This study examined the effect of different acidic treatments and the role of a phosphate monomer in a silane coupling agent on the durability of the dual-cure resin cement/silicon oxide bond. Ceramic blocks (Vita Celay Blanks) were cut into multiple 3 mm-thick slices and polished using 600 grit SiC paper. Two pairs were left untreated [controls (CTRL)], two pairs were treated with 40% phosphoric acid and rinsed with water for 30 s (PA), and another two pairs treated with 20% hydrofluoric acid followed by 30 s water rinsing (HF). Half the specimens were silanated with Tokuso Ceramics Primer (TCP) (Tokuyama) and the other half with TCP formulated without phosphate monomer (TCP-NoPM). All the pairs were bonded with Bistite II dual-cure resin cement (Tokuyama) and light cured. After 24 h water storage at 37 degrees C, 0.7 mm-thick slabs were serially sectioned. Immediately, after 6 months and after 1 year of water storage, two slabs were randomly selected from each subgroup, and sliced into beams (6 x 0.7 x 0.7 mm) for the microtensile bond strength (muTBS) test. The muTBS data were statistically analyzed using multiple Wilcoxon Signed Rank tests (p < 0.05). Failure modes were determined using a confocal laser-scanning microscope. Ceramic surface morphology after the different acidic treatments was examined using an SEM. After 1 day, in the case of silane treatment with TCP, there were no significant differences in muTBS between the control and acid-treated groups (p > 0.05), whereas with TCP-NoPM, the muTBS of the control was significantly lower than the acid-treated groups (p < 0.05). All the TCP and acid-treated TCP-NoPM groups exhibited significant reductions in muTBS after 6 months (p < 0.05). After 1 year, the muTBS of the acid-treated TCP groups were not significantly different from the control TCP group (p > 0.05). There was also no significant difference between the HF-treated TCP and TCP-NoPM groups (p > 0.05) after 1 year, all exhibiting greater than 10 MPa tensile bond strength. It is suggested that acidic pretreatment of the ceramic surface does not improve the durability of the dual-cure resin cement/silicon oxide ceramic bond when an acidic phosphate monomer is present as an activator in a ceramic primer. PMID:15625674