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1

Grating competition for charge carriers in photorefractive bismuth silicon oxide  

NASA Astrophysics Data System (ADS)

Charge carrier competition between the gratings produced in degenerate four-wave mixing in bismuth silicon oxide reduces steady-state diffraction efficiency, suppresses several processes of transient diffraction efficiency, and changes the concavity of reflection grating development.

Khoury, Jehad; Cronin-Golomb, Mark; Woods, Charles

1995-01-01

2

Silicon-based bridge wire micro-chip initiators for bismuth oxide-aluminum nanothermite  

Microsoft Academic Search

We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 C melting point solder alloy bonding procedure and integrated with a bismuth oxide-aluminum nanothermite energetic

C. S. Staley; C. J. Morris; R. Thiruvengadathan; S. J. Apperson; K. Gangopadhyay; S. Gangopadhyay

2011-01-01

3

Silicon-based bridge wire micro-chip initiators for bismuth oxide-aluminum nanothermite  

NASA Astrophysics Data System (ADS)

We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 C melting point solder alloy bonding procedure and integrated with a bismuth oxide-aluminum nanothermite energetic composite. The electro-thermal conversion efficiency of the initiators is enhanced by the use of a nanoporous silicon bed which impedes thermal coupling between the bridge wire and bulk silicon substrate while maintaining the structural integrity of the device. Electrical behaviors of the ignition elements are investigated to extract minimum input power and energy requirements of 382.4 mW and 26.51 J, respectively, both in the absence and presence of an injected bismuth oxide-aluminum nanothermite composition. Programmed combustion of bismuth oxide-aluminum nanothermite housed within these initiators is demonstrated with a success rate of 100% over a 30 to 80 J range of firing energies and ignition response times of less than 2 s are achieved in the high input power operation regime. The micro-initiators reported here are intended for use in miniaturized actuation technologies.

Staley, C. S.; Morris, C. J.; Thiruvengadathan, R.; Apperson, S. J.; Gangopadhyay, K.; Gangopadhyay, S.

2011-11-01

4

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

5

Bismuth based oxide electrolytes structure and ionic conductivity  

Microsoft Academic Search

Bismuth oxide systems exhibit high oxide ion conductivity and have been proposed as good electrolyte materials for applications such as solid oxide fuel cells and oxygen sensors. However, due to their instability under conditions of low oxygen partial pressures there has been difficulty in developing these materials as alternative electrolyte materials compared to the state-of-the-art cubic stabilised zirconia electrolyte. Bismuth

N. M. Sammes; G. A. Tompsett; H. Nfe; F. Aldinger

1999-01-01

6

Anisotropic oxidation of bismuth nanostructures: Evidence for a thin film allotrope of bismuth  

NASA Astrophysics Data System (ADS)

We present evidence that ultra-thin Bi(110) nanostructures oxidise from the edges, and that their top surfaces remain unoxidised. Even after prolonged oxidation, clean (unoxidised) bismuth is present in nanostructures that are less than 5 monolayers thick. Since the (110) surface of bulk bismuth is known to be readily oxidised, this is strong evidence for a thin film allotrope of bismuth. We present a comparison with calculated structures and the structures of polymeric nitrogen, which suggests that the allotrope is one of several complex or hybrid paired-layer structures.

Kowalczyk, P. J.; Belic, D.; Mahapatra, O.; Brown, S. A.; Kadantsev, E. S.; Woo, T. K.; Ingham, B.; Kozlowski, W.

2012-04-01

7

Hydrogen implanted silicon oxidation  

Microsoft Academic Search

The oxidation rate and the oxide thickness of the hydrogen ion implanted silicon wafers were examined. It was observed that the native oxide thickness is higher for the H+ implanted Si(100) compared to the Si(111). Also the native oxide thickness depended on the implanted hydrogen distribution. The thickness increased with the hydrogen con-centration. The oxide thickness after wet oxidization of

S. Hava; B. M. Lacquet; P. L. Swart

1989-01-01

8

Buried oxide layer in silicon  

DOEpatents

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

Sadana, Devendra Kumar (Pleasantville, NY); Holland, Orin Wayne (Lenoir, TN)

2001-01-01

9

Nonlinearity of the photorefractive response upon two-beam interaction in a bismuth silicon oxide crystal in an alternating electric field  

SciTech Connect

Nonlinearity of the photorefractive response is studied experimentally and theoretically upon two-beam interaction of light waves in a bismuth silicate crystal placed in an external meander electric field. The experimental data are shown to be in good agreement with a model, taking into account the influence of the second harmonic of the space-charge field on a photorefractive grating. The concentration of acceptors in a crystal and a product of the mobility of charge carriers by their recombination time are estimated from a comparison of the experimental and calculated data. (nonlinear optical phenomena)

Kobozev, O V; Mandel', A E; Shandarov, S M; Petrov, S A [Division of Electronic Devices, Tomsk University of Control Systems and Radioelectronics, Tomsk (Russian Federation); Kargin, Yu F [N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation)

2000-06-30

10

Hydrogen implanted silicon oxidation  

Microsoft Academic Search

The oxidation rate and the oxide thickness of the hydrogen ion implanted silicon wafers were examined. It was observed that\\u000a the native oxide thickness is higher for the H+ implanted Si(100) compared to the Si(111). Also the native oxide thickness depended on the implanted hydrogen distribution.\\u000a The thickness increased with the hydrogen con-centration. The oxide thickness after wet oxidization of

S. Hava; B. M. Lacquet; P. L. Swart

1989-01-01

11

Tributylphosphate Extraction Behavior of Bismuthate-Oxidized Americium  

Microsoft Academic Search

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

Bruce J. Mincher; Leigh R. Martin; Nicholas C. Schmitt

2008-01-01

12

Spectroscopic and microscopic study of the corrosion of iron silicon steel by lead bismuth eutectic (LBE) at elevated temperatures  

NASA Astrophysics Data System (ADS)

The performance of iron silica alloys with different silicon composition was evaluated after exposure to an isothermal bath of lead bismuth eutectic (LBE). Four alloys were evaluated: pure iron, Fe 1.24%Si, Fe 2.55%Si and Fe 3.82%Si. The samples were exposed to LBE in a dynamic corrosion cell for periods from 700 to 1000 h at a temperature of 550 C. After exposure, the thickness and composition of the oxide layer were examined using optical microscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS), including sputter depth profiling. Particular attention was paid to the role, spatial distribution, and chemical speciation of silicon. Low-binding-energy silicon (probably silicates or SiO44-) was found in the oxide; while elemental silicon (Si) was found in the metal as expected, and silica (SiO2) was found at the bottom of the oxide layer, consistent with the formation of a layer between the oxide and the metal. Alloys with low concentrations of Si contained only silicate in the oxide. Alloys with higher concentrations of Si contained a layer of silica at the boundary between the oxide and the bulk metal. All of the alloys examined showed signs of oxide failure. This study has implications for the role of silicon in the stability of the oxide layer in the corrosion of steel by LBE.

Johnson, Allen L.; Loewen, Eric P.; Ho, Thao T.; Koury, Dan; Hosterman, Brian; Younas, Umar; Welch, Jenny; Farley, John W.

2006-05-01

13

Crystalline oxides on silicon.  

PubMed

This review outlines developments in the growth of crystalline oxides on the ubiquitous silicon semiconductor platform. The overall goal of this endeavor is the integration of multifunctional complex oxides with advanced semiconductor technology. Oxide epitaxy in materials systems achieved through conventional deposition techniques is described first, followed by a description of the science and technology of using atomic layer-by-layer deposition with molecular beam epitaxy (MBE) to systematically construct the oxide-silicon interface. An interdisciplinary approach involving MBE, advanced real-space structural characterization, and first-principles theory has led to a detailed understanding of the process by which the interface between crystalline oxides and silicon forms, the resulting structure of the interface, and the link between structure and functionality. Potential applications in electronics and photonics are also discussed. PMID:20432223

Reiner, James W; Kolpak, Alexie M; Segal, Yaron; Garrity, Kevin F; Ismail-Beigi, Sohrab; Ahn, Charles H; Walker, Fred J

2010-07-20

14

Spray pyrolysed bismuth oxide thin films and their characterization  

SciTech Connect

Uniform, adherent and reproducible bismuth oxide thin films have been deposited on glass substrates from aqueous Bi(NO{sub 3}){sub 3} solution, using the solution spray technique. Their structural, surface morphological, optical, and electrical properties were investigated by XRD, AFM, optical absorption, electrical resistivity and thermo-emf measurements. The structural analysis from XRD pattern showed the formation of mixed phases of monoclinic Bi{sub 2}O{sub 3} (predominant), tetragonal {beta}-Bi{sub 2}O{sub 3} and nonstiochiometric Bi{sub 2}O{sub 2.33}. The surface morphological studies on atomic force micrographs revealed round grain morphology of bismuth oxide crystallites. The optical studies showed a direct band gap of 2.90 eV for as-prepared bismuth oxide films. The electrical resistivity measurements of bismuth oxide films indicated a semiconducting behavior with the room temperature electrical resistivity of the order of 10{sup 7} {omega} cm. From thermo-emf measurements, the electrical conductivity was found to be of n-type.

Gujar, T.P. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur-416004 (M.S.) (India)]. E-mail: gujar_tp@yahoo.com; Shinde, V.R. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur-416004 (M.S.) (India); Lokhande, C.D. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur-416004 (M.S.) (India)]. E-mail: l_chandrakant@yahoo.com

2006-08-10

15

Bismuth-based oxide semiconductors: Mild synthesis and practical applications  

NASA Astrophysics Data System (ADS)

In this dissertation study, bismuth based oxide semiconductors were prepared using 'mild' synthesis techniques---electrodeposition and solution combustion synthesis. Potential environmental remediation and solar energy applications of the prepared oxides were evaluated. Bismuth vanadate (BiVO4) was prepared by electrodeposition and solution combustion synthesis. A two step electrosynthesis strategy was developed and demonstrated for the first time. In the first step, a Bi film was first electrodeposited on a Pt substrate from an acidic BiCl3 medium. Then, this film was anodically stripped in a medium containing hydrolyzed vanadium precursor, to generate Bi3+, and subsequent BiVO4 formation by in situ precipitation. The photoelectrochemical data were consistent with the in situ formation of n-type semiconductor films. In the solution combustion synthesis procedure, BiVO4 powders were prepared using bismuth nitrate pentahydrate as the bismuth precursor and either vanadium chloride or vanadium oxysulfate as the vanadium precursor. Urea, glycine, or citric acid was used as the fuel. The effect of the vanadium precursor on the photocatalytic activity of combustion synthesized BiVO 4 was evaluated in this study. Methyl orange was used as a probe to test the photocatalytic attributes of the combustion synthesized (CS) samples, and benchmarked against a commercial bismuth vanadate sample. The CS samples showed superior activity to the commercial benchmark sample, and samples derived from vanadium chloride were superior to vanadium oxysulfate counterparts. The photoelectrochemical properties of the various CS samples were also studied and these samples were shown to be useful both for environmental photocatalytic remediation and water photooxidation applications. Silver bismuth tungstate (AgBiW2O8) nanoparticles were prepared for the first time by solution combustion synthesis by using silver nitrate, bismuth nitrate, sodium tungstate as precursors for Ag, Bi, and W respectively and urea as the fuel. The photocatalytic activity of these nanoparticles was superior to a sample prepared by solid-state synthesis. The combustion-synthesized particles were subsequently modified with Pt catalyst islands using a photodeposition technique and then used for the photo-generation of syngas (CO + H2). Formic acid was used in these experiments for in situ generation of CO2 and its subsequent reduction to CO. In the absence of Pt modification, H2 was not obtained. These results were compared with those obtained with acetic acid in place of formic acid, and finally the mechanistic pathways for syngas and methane photogeneration are presented.

Timmaji, Hari Krishna

16

Functionalizable magnetic/luminous silicon/bismuth core/shell nanocrystalline particles  

NASA Astrophysics Data System (ADS)

Bismuth-covered silicon nanocrystalline quantum dots, depending on size and coverage, are predicted to exhibit characteristics of magnetic nanoparticles and luminescent semiconductor dots, accompanied by manifestations of metal-insulator transition. These properties, emerging from accurate time-dependent and standard density functional theory calculations can be critical for the development of nanoscale optoelectronic and opto-magnetic switches, and in quantum computing.

Zdetsis, Aristides D.

2011-05-01

17

METHOD OF PREPARING URANIUM, THORIUM, OR PLUTONIUM OXIDES IN LIQUID BISMUTH  

DOEpatents

A method is given for forming compositions, as well as the compositions themselves, employing uranium hydride in a liquid bismuth composition to increase the solubility of uranium, plutonium and thorium oxides in the liquid bismuth. The finely divided oxide of uranium, plutonium. or thorium is mixed with the liquid bismuth and uranium hydride, the hydride being present in an amount equal to about 3 at. %, heated to about 5OO deg C, agitated and thereafter cooled and excess resultant hydrogen removed therefrom.

Davidson, J.K.; Robb, W.L.; Salmon, O.N.

1960-11-22

18

EQCM study on the oxidation\\/reduction of bismuth sulfide thin films  

Microsoft Academic Search

The oxidation\\/reduction of bismuth sulfide thin films deposited on an Au electrode using the successive ionic layer adsorption and reaction method has been investigated by electrochemical quartz crystal microbalance combined with cyclic voltammetry and X-ray photoelectron spectroscopy. It has been shown that the oxidation\\/reduction of bismuth sulfide film depends on the nature of anion. In the acetate solution the bismuth

L. Tamaauskait?-Tamai?nait?; G. Valiulien?; A. ielien?; B. imk?nait?-Stanynien?; L. Narukevi?ius; A. Sudavi?ius

2010-01-01

19

Selective oxidation of hydrogen sulfide to ammonium thiosulfate and sulfur over vanadium-bismuth oxide catalysts  

Microsoft Academic Search

The selective oxidation of hydrogen sulfide containing excess water and ammonia was studied over vanadium-bismuth mixed oxide catalysts. The investigation was focused on understanding the complex reaction steps and the roles of each metal oxide. Therefore, supported V2O5\\/TiO2, V-Bi-O\\/TiO2 catalysts and a mechanical mixture of V2O5 + Bi2O3 were tested in the reaction. Ammonia reacted either with H2S or SO2,

Young-Gu Cho; Dae-Kwang Park; Dae-Won Park; Hee-Chul Woo; Jong-Shik Chung

2002-01-01

20

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

SciTech Connect

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.

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

21

Improved cycling performance of bismuth-modified amorphous manganese oxides as cathodes for rechargeable lithium batteries  

Microsoft Academic Search

Bismuth-modified amorphous manganese oxides were synthesized via a room temperature aqueous route. They were galvanostatically tested as intercalation cathodes for rechargeable lithium batteries at 1mAcm?2 between 1.5 and 4.3V. In sharp contrast to severe capacity fading of unmodified amorphous manganese oxide synthesized by the same route, a stable cycling performance of the bismuth-modified amorphous manganese oxide was observed. After an

Jingsi Yang; Terrill B Atwater; Jun John Xu

2005-01-01

22

Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides  

SciTech Connect

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.

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

23

Tributylphosphate Extraction Behavior of Bismuthate-Oxidized Americium  

SciTech Connect

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.

Mincher; Leigh R. Martin; Nicholas C. Schmitt

2008-08-01

24

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

PubMed Central

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.

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

2013-01-01

25

Mechanism of carrier transport through a silicon-oxide layer for ?indium-tin-oxide\\/silicon-oxide\\/silicon? solar cells  

Microsoft Academic Search

The mechanism of carrier transport through a thin silicon-oxide layer for ?spray-deposited indium-tin-oxide (ITO)\\/silicon-oxide\\/Si? solar cells has been studied by measurements of the dark current density as a function of the thickness of the silicon-oxide layer, together with the observation of transmission electron micrographs. Cross-sectional transmission electron micrography shows that a uniform silicon-oxide layer with the thickness of ?2 nm

H. Kobayashi; T. Ishida; Y. Nakato; H. Mori

1995-01-01

26

Oxidation of bismuth nanodroplets deposit on GaAs substrate  

NASA Astrophysics Data System (ADS)

Bismuth nanodroplets on GaAs substrate were obtained by metalorganic vapor phase epitaxy (MOVPE). New products have been synthesized when Bi nanodroplets are heated under oxygen atmosphere. The oxidation process of Bi nanodroplets consists of a heating from the room temperature to different oxidation temperatures (350, 500, 600 ?C) with a temperature rate of 14 ?C/min. The annealing duration was fixed to 30 min. The presence of oxygen in the products was confirmed by energy dispersive X-ray (EDX) measurements using a scanning electron microscope (SEM). SEM images show that Bi microcomposites density decrease and their size increases with increasing annealing temperature. After X-ray diffraction analysis of the products no obvious peaks could be observed. The reflectance spectra of the products were studied in spectral domains ranged from 200 nm to 1100 nm. By fitting the reflectivity signal, we extracted the thickness of the products and their refractive index variation versus wavelength. The results show that the thickness of the samples increases with increasing annealing temperature. The photoluminescence (PL) spectra under excitation at 325 nm shows a broad emission centered at around 1.92 eV.

Fitouri, H.; Boussaha, R.; Rebey, A.; El Jani, B.

2013-09-01

27

Morphology modulated growth of bismuth tungsten oxide nanocrystals  

SciTech Connect

Two kinds of bismuth tungsten oxide nanocrystals were prepared by microwave hydrothermal method. The morphology modulation of nanocrystals synthesized with precursor suspension's pH varied from 0.25 (strong acid) to 10.05 (base) was studied. The 3D flower like aggregation of Bi{sub 2}WO{sub 6} nanoflakes was synthesized in acid precursor suspension and the nanooctahedron crystals of Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were synthesized in alkalescent precursor. The dominant crystal is changed from Bi{sub 2}WO{sub 6} to Bi{sub 3.84}W{sub 0.16}O{sub 6.24} when the precursor suspension changes from acid to alkalescence. The growth mechanisms of Bi{sub 2}WO{sub 6} and Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were attributed to the different solubility of WO{sub 4}{sup 2-} and [Bi{sub 2}O{sub 2}]{sup 2+} in precursor suspensions with various pH. For the decomposition of Rhodamine B (RhB) under visible light irradiation ({lambda}>400 nm), different morphology of Bi{sub 2}WO{sub 6} crystal samples obtained by microwavesolvothermal process showed different photocatalytic activity. - Graphical abstract: The morphology modulation of bismuth tungsten oxide nanocrystals synthesized by microwave hydrothermal method with precursor suspension's pH varied from 0.25 (strong acid) to 10.05 (base) was studied. The 3D flower like aggregation of Bi{sub 2}WO{sub 6} nanoflakes and nanooctahedron crystals of Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were prepared. The growth mechanisms of Bi{sub 2}WO{sub 6} and Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were attributed to the different precipitation ability and solubility of H{sub 2}WO{sub 4} and Bi(OH){sub 3} in precursor suspensions with various pH. The photocatalytic evaluation, via the decomposition of Rhodamine B (RhB) under visible light irradiation ({lambda}>420 nm), reveals that nanocrystalline Bi{sub 2}WO{sub 6} samples obtained in different condition exhibit different photocatalytic activities which depend on pH value of the precursor suspensions.

Yao Shushan [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China); Wei, Jiyong [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China); Chemistry and Chemical Engineering College, Shandong University, Jinan 250100 (China); Huang Baibiao [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China)], E-mail: bbhuang@sdu.edu.cn; Feng Shengyu [Chemistry and Chemical Engineering College, Shandong University, Jinan 250100 (China); Zhang Xiaoyang; Qin Xiaoyan; Wang Peng; Wang Zeyan; Zhang Qi; Jing Xiangyang; Zhan Jie [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China)

2009-02-15

28

Epitaxial Growth of Strontium Bismuth Tantalate\\/Niobate of Buffered Magnesium Oxide Substrates  

Microsoft Academic Search

Epitaxial films of strontium bismuth tantalate (SrBiTaO, SBT) and strontium bismuth niobate (SrBiNbO, SBN) were grown using solution deposition techniques on magnesium oxide (MgO) substrates buffered with a 100 nm layer of lanthanum manganate (LaMnO, LMO). Film structure and texture analyses were carried out using x-ray diffraction. Theta-2theta diffraction patterns were consistent with a c-axis aligned structure for both the

George H Thomas; Johathan Morrell; Tolga Aytug; Ziling Xue; David B Beach

2006-01-01

29

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

NASA Astrophysics Data System (ADS)

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 ?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.

Gao, Zheng; Qin, Haiming; Yan, Tao; Liu, Hong; Wang, Jiyang

2011-12-01

30

Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides  

NASA Astrophysics Data System (ADS)

Heat capacity and enthalpy increments of ternary bismuth tantalum oxides Bi4Ta2O11, Bi7Ta3O18 and Bi3TaO7 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 Cpm=445.8+0.005451T-7.489106/T2 J K-1 mol-1, Cpm=699.0+0.05276T-9.956106/T2 J K-1 mol-1 and Cpm=251.6+0.06705T-3.237106/T2 J K-1 mol-1 for Bi3TaO7, Bi4Ta2O11 and for Bi7Ta3O18, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, Sm(298.15 K)=449.62.3 J K-1 mol-1 for Bi4Ta2O11, Sm(298.15 K)=743.03.8 J K-1 mol-1 for Bi7Ta3O18 and Sm(298.15 K)=304.31.6 J K-1 mol-1 for Bi3TaO7, were evaluated from the low-temperature heat capacity measurements.

Leitner, J.; Jake, V.; Sofer, Z.; Sedmidubsk, D.; R?i?ka, K.; Svoboda, P.

2011-02-01

31

Investigation on bismuth-oxide photonic crystal fiber for optical parametric amplification  

NASA Astrophysics Data System (ADS)

A hexagonal solid-core bismuth-oxide micro-structure fiber is developed to balance its dispersion and nonlinearity. This simulation and calculation results show that the bismuth-oxide photonic crystal fiber (Bi-PCF) has near zero dispersion around 1550 nm. Its dispersion slop in the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model field distribution are obtained. Compared with the experimental results by SiO2-PCF, it can be seen that the Bi-PCF shows excellent characteristics for the optical parametric amplification (OPA).

Jin, Cang; Rao, Lan; Yuan, Jin-hui; Shen, Xiang-wei; Yu, Chong-xiu

2011-05-01

32

Relative stability of multiple bonds between silicon and bismuth. A theoretical study  

NASA Astrophysics Data System (ADS)

Substituent effects on the potential energy surface of XSiBi (X = H, Li, Na, BeH, MgH, BH 2, AlH 2, CH 3, SiH 3, NH 2, PH 2, OH, SH, F, and Cl) were investigated by using B3LYP/Def2-TZVP, B3PW91/Def2-TZVPP, and CCSD(T) methods. The isomers include structures with formal double (Si dbnd BiX) and triple (XSi tbnd Bi) bonds to silicon-bismuth, so a direct comparison of these types of species is possible. Our model calculations indicate that electropositively substituted Si dbnd BiX species are thermodynamically and kinetically more stable than their isomeric XSi tbnd Bi molecules. Moreover, the theoretical findings suggest that F, OH, NH 2, and CH 3 substitution prefer to shift the double bond (Si dbnd BiX) by forming a triple bond (XSi tbnd Bi).

Ma, Jia-Ying; Su, Ming-Der

2011-08-01

33

Tailoring Silicon Oxycarbide Glasses for Oxidative Stability.  

National Technical Information Service (NTIS)

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...

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

1997-01-01

34

Ultrathin {001}-oriented bismuth tungsten oxide nanosheets as highly efficient photocatalysts.  

PubMed

Orient express: Ultrathin nanosheets of bismuth tungsten oxide (Bi2 WO6 ) with {001}-orientation are prepared by a pH-controlled synthesis. The sheets have aspect ratios as large as 30:1, and offer superior adsorption and hole oxidation properties as well as prolonged charge-carrier lifetimes.The ultrathin structures show enhanced photocatalytic activity towards organic contaminant degradation and water oxidation. PMID:24023041

Sun, Songmei; Wang, Wenzhong; Zhang, Ling; Gao, Erping; Jiang, Dong; Sun, Yongfu; Xie, Yi

2013-09-10

35

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

Microsoft Academic Search

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.

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

2004-01-01

36

AFM and MFM characterization of oxide layers grown on stainless steels in lead bismuth eutectic  

Microsoft Academic Search

Fast reactors and spallation neutron sources may use lead bismuth eutectic (LBE) as a coolant. Its thermal physical and neutronic properties make it a high performance nuclear coolant and spallation target. The main disadvantage of LBE is that it is corrosive to most steels and container materials. Active control of oxygen in LBE will allow the growth of protective oxides

P. Hosemann; M. Hawley; G. Mori; N. Li; S. A. Maloy

2008-01-01

37

Two Step Oxidation Processes in Silicon.  

National Technical Information Service (NTIS)

We have studied dielectric breakdown characteristics of this (approx. 10nm) silicon dioxide films grown on silicon under the following conditions: (A) Standard oxidation process with the oxides grown at 800C; (B) Annealing the oxides at 1000C in argon for...

N. M. Ravindra D. Fathy J. Narayan J. K. ivastava E. A. Irene

1986-01-01

38

Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement.  

PubMed

The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC) was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO), determined by weight. Mineral trioxide aggregate (MTA) was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ?E, ?a, ?b and ?L values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (p<0.05). The cements in which bismuth oxide was added showed radiopacity corresponding to the ISO recommendations (>3 mm equivalent of Al). The MTA group was statistically similar to the CSC/30% BO group (p>0.05). In regard to color, the increase of bismuth oxide resulted in a decrease in the ?E value of the calcium silicate cement. The CSC group presented statistically higher ?E values than the CSC/50% BO group (p<0.05). The comparison between 24 hours and 7 days showed higher ?E for the MTA group, with statistical differences for the CSC/15% BO and CSC/50% BO groups (p<0.05). After 30 days, CSC showed statistically higher ?E values than CSC/30% BO and CSC/50% BO (p<0.05). In conclusion, the increase in radiopacity provided by bismuth oxide has no relation to the color alteration of calcium silicate-based cements. PMID:23903861

Marciano, Marina Anglica; Estrela, Carlos; Mondelli, Rafael Francisco Lia; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro

39

Method of forming buried oxide layers in silicon  

DOEpatents

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

Sadana, Devendra Kumar (Pleasantville, NY); Holland, Orin Wayne (Lenoir City, TN)

2000-01-01

40

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

SciTech Connect

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.

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

2011-12-31

41

Thermal Oxidation of Antimony-Doped Silicon  

NASA Astrophysics Data System (ADS)

Thermal oxidation of silicon in which antimony was doped has been investigated. The oxidation rate increases with the increase of antimony concentration at oxidation temperatures of 950C, 1035C and 1100C. This tendency is similar to that of high-concentration phosphorus-doped silicon. The degree of enhancement of the oxidation rate by antimony doping is higher than that by phosphorus doping.

Ishikawa, Yutaka

2002-04-01

42

Deposition of barium potassium bismuth oxide (BKBO) thin films by laser ablation  

Microsoft Academic Search

High-transition-temperature barium potassium bismuth oxide (BKBO) thin films have been deposited by pulsed-laser ablation. The best results were obtained by ablating from a potassium-rich single target in a pure argon background onto ?100? SrTiO3 substrates. Films with superconducting onset and zero-resistance temperatures of 28.5 and 27.5 K, respectively, were routinely obtained, with room-temperature resistivity as low as 250 ??-cm. X-ray

R. C. Lacoe; J. P. Wendt; P. M. Adams

1993-01-01

43

Investigation of bismuth oxide α-BiO by the muon method  

Microsoft Academic Search

The muon method has been used for the first time to investigate bismuth oxide α-BiO. It was shown that the observed fast ( 10 μ s⁻¹) and slow ( 0.1 μs⁻¹) muon-spin relaxations are not successive stages of the same relaxation process, but rather they are associated with muons localized in two different sites of the crystal lattice. It is

V. G. Grebinnik; V. N. Duginov; V. A. Zhukov; T. N. Mamedov

1995-01-01

44

Wavelength tunable passively mode-locked bismuth oxide-based erbium-doped fiber laser  

Microsoft Academic Search

The broadband gain of bismuth oxide-based erbium-doped fiber has been used to obtain wavelength-tunable mode-locking over a 30 nm range from 1570 to 1600 nm. Passive mode-locking using a proton-bombarded semiconductor saturable absorber mirror produces 2.2-ps pulses at a repetition rate of 17 MHz. After external frequency chirp compensation, 288-fs pulses are obtained at 1600 nm.

Hideyuki Sotobayashi; Juliet T. Gopinath; Elisabeth M. Koontz; Leslie A. Kolodziejski; Erich P. Ippen

2004-01-01

45

Easy synthesis of bismuth iron oxide nanoparticles as photocatalyst for solar hydrogen generation from water  

Microsoft Academic Search

In this study, high purity bismuth iron oxide (BiFeO3\\/BFO) nanoparticles of size 50-80 nm have been successfully synthesized by a simple sol-gel method using urea and polyvinyl alcohol at low temperature. X-ray diffraction (XRD) measurement is used to optimize the synthetic process to get highly crystalline and pure phase material. Diffuse reflectance ultraviolet-visible (DRUV-Vis) spectrum indicates that the absorption cut-off

Jinyi Deng

2010-01-01

46

Nonpolar Bistable Resistive Switching Behaviors of Bismuth Titanate Oxide Thin Film  

Microsoft Academic Search

Nonpolar bistable resistive switching behaviors of sol-gel derived bismuth titanate oxide (BTO) thin film are investigated in this study. The BTO thin film memory device without thermal treatment shows higher resistance ratio (? 10) than the other annealed devices. The resistive switching behavior of the Pt\\/BTO\\/LNO\\/Pt device is reproducible and can be traced over 100 times. Both low resistance state

Meng-Han Lin; Ming-Chi Wu; Chun-Chieh Lin; Tseung-Yuen Tseng

2009-01-01

47

A ferroelectric oxide made directly on silicon.  

PubMed

Metal oxide semiconductor field-effect transistors, formed using silicon dioxide and silicon, have undergone four decades of staggering technological advancement. With fundamental limits to this technology close at hand, alternatives to silicon dioxide are being pursued to enable new functionality and device architectures. We achieved ferroelectric functionality in intimate contact with silicon by growing coherently strained strontium titanate (SrTiO3) films via oxide molecular beam epitaxy in direct contact with silicon, with no interfacial silicon dioxide. We observed ferroelectricity in these ultrathin SrTiO3 layers by means of piezoresponse force microscopy. Stable ferroelectric nanodomains created in SrTiO3 were observed at temperatures as high as 400 kelvin. PMID:19372426

Warusawithana, Maitri P; Cen, Cheng; Sleasman, Charles R; Woicik, Joseph C; Li, Yulan; Kourkoutis, Lena Fitting; Klug, Jeffrey A; Li, Hao; Ryan, Philip; Wang, Li-Peng; Bedzyk, Michael; Muller, David A; Chen, Long-Qing; Levy, Jeremy; Schlom, Darrell G

2009-04-17

48

Spin dependent recombination based magnetic resonance spectroscopy of bismuth donor spins in silicon at low magnetic fields  

NASA Astrophysics Data System (ADS)

Low-field (6-110 mT) magnetic resonance of bismuth (Bi) donors in silicon has been observed by monitoring the change in photoconductivity induced by spin dependent recombination. The spectra at various resonance frequencies show signal intensity distributions drastically different from that observed in conventional electron paramagnetic resonance, attributed to different recombination rates for the forty possible combinations of spin states of a pair of a Bi donor and a paramagnetic recombination center. An excellent tunability of Bi excitation energy for the future coupling with superconducting flux qubits at low fields has been demonstrated.

Mortemousque, P. A.; Sekiguchi, T.; Culan, C.; Vlasenko, M. P.; Elliman, R. G.; Vlasenko, L. S.; Itoh, K. M.

2012-08-01

49

Broadband dielectric spectroscopy of oxidized porous silicon  

Microsoft Academic Search

Dielectric measurements accompanied by infrared absorption and photoluminescence (PL) spectroscopy were used to investigate the electrical and optical properties of oxidized porous silicon (PS). As opposed to non-oxidized PS, only high temperature relaxation processes could be resolved for oxidized PS. Two relaxation processes have been observed. The first process is related to dc-conductivity that dominates at high temperatures and low

Ekaterina Axelrod; Benayahu Urbach; Amir Sa'ar; Yuri Feldman

2006-01-01

50

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

NASA Astrophysics Data System (ADS)

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 were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), optical absorption and dielectric measurement techniques. The results show that electrodeposition method allows to synthesis BFO films. The films are free from pinholes and cracks. The magnitudes of dielectric constant and loss tangent showed inverse frequency dependence.

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

2006-03-01

51

The effect and mechanism of bismuth doped lead oxide on the performance of lead-acid batteries  

Microsoft Academic Search

Flooded automotive and motorcycle lead-acid batteries were manufactured from three kinds of lead oxides including electrolyzed pure lead (99.99wt.% Pb) oxide, electrolyzed pure lead oxide doped with Bi2O3 (0.02wt.% Bi2O3) and bismuth-bearing refined lead (0.02wt.% Bi) oxide. The first cranking and cold cranking curves of the automotive batteries show that there is no obvious difference among the above lead oxides.

H. Y Chen; L Wu; C Ren; Q. Z Luo; Z. H Xie; X Jiang; S. P Zhu; Y. K Xia; Y. R Luo

2001-01-01

52

Oxidation of evaporated porous silicon rugate filters  

NASA Astrophysics Data System (ADS)

Rugate filters are thin-film optical interference coatings with sinusoidal variation of the refractive index. Several of these filters were fabricated with glancing angle deposition, which exploits atomic competition during growth to create nanoporous materials with controllable effective refractive index. This method enables the fabrication of devices with almost arbitrary refractive index profiles varying between the ambient, 1.0, and the index of the film material, in this case silicon with an index of 4.0 (at 600 nm). As these filters are inherently porous, oxidation of the silicon can occur throughout the device layer, and here we study the intentional oxidation of silicon filters by high-temperature reaction with gaseous oxygen. We find that a significant portion of the silicon filter oxidizes in approximately 10 min when heated to 600 C-650 C in an oxygen environment; oxidation then continues slowly over several hours. The presence of water vapor has little apparent effect on the oxidation reaction, and attempts to oxidize with ozone at room temperature were unsuccessful. As silicon filters oxidize to become silica, spectral blueshifts and increased short-wavelength transmittance are observed. Measured and calculated transmittance spectra generally agree, although the lack of absorption and dispersion in the theoretical model limits detailed comparison.

Robbie, Kevin; Cui, Yan; Elliott, Chelsea; Kaminska, Kate

2006-11-01

53

Chemical and Electrochemical Behavior of Carbonate Melts Containing Silicon Oxide  

Microsoft Academic Search

The optimal conditions of electrochemical synthesis of silicon carbide in carbonate melts containing silicon oxide were determined on the basis of thermodynamic calculations and data of cyclic voltammetry.

S. V. Devyatkin; A. D. Pisanenko; V. I. Shapoval

2002-01-01

54

Process for producing bismuth-based superconducting oxide  

US Patent & Trademark Office Database

The present process for producing a Bi-based superconducting oxide includes the steps of molding a material powder and subjecting the molded article to partial melting and then to crystallization in the presence of oxygen. In that case, the molded article is annealed, after the partial melting, to the crystallization temperature and subjected to crystallization at that temperature. Also, the article after the crystallization is cooled and the cooled article is heat-treated in an inert gas atmosphere. According to the above process, there can be obtained a Bi-based superconducting oxide having excellent superconducting properties.

1992-02-18

55

Tin oxide microsensors on thin silicon membranes  

Microsoft Academic Search

Tin oxide based microsensors with integrated polysilicon heaters were fabricated on thin silicon membranes generated by anisotropic wet chemical etching using ethylene diamine pyrocatechol as the etchant. Good thermal isolation and lower power consumption were achieved. The sensing elements, tin oxide thin films, were prepared either by sputter deposition or by metallo-organic deposition. The completed microsensors showed good response to

Shih-Chia Chang; David B. Hicks

1986-01-01

56

Deposition of barium potassium bismuth oxide (BKBO) thin films by laser ablation  

Microsoft Academic Search

High-transition-temperature barium potassium bismuth oxide (BKBO) thin films have been deposited by pulsed-laser ablation. The best results were obtained by ablating from a potassium-rich single target in a pure argon background onto 100-line SrTiO3 substrates. Films with superconducting onset and zero-resistance temperatures of 28.5 and 27.5 K, respectively, were routinely obtained, with room-temperature resistivity as low as 250 micro-ohms-cm. X-ray

R. C. Lacoe; J. P. Wendt; P. M. Adams

1993-01-01

57

Heat-reflecting windows using gold and bismuth oxide films  

Microsoft Academic Search

Thin gold films sandwiched between certain metal oxide layers possess a high electrical conductivity and high optical transparency. They also have a high infra-red reflectance, and may be used as transparent heat-reflecting coatings if their yellowish tinted colour in transmitted light can be tolerated. The observation window of an enclosure exposed to infra-red radiation was coated with different film combinations,

L. Holland; G. Siddall

1958-01-01

58

Comparisons of the Oxide Layer Between Static Liquid-Bismuth-Eutectic and Gas Environments  

SciTech Connect

The competition between corrosion and oxidation on a steel surface immersed in lead alloys with controlled oxygen leads to different oxide-layer characteristics as compared with those formed in gases. The presence of a liquid metal [liquid lead or lead-bismuth eutectic (LBE)] can either enhance or reduce the oxidation rate, resulting in different oxide growth rates and microstructures. Based on analysis of experimental results in static LBE/lead and gases under the same experimental conditions, we predict the oxide-layer structure and thickness as functions of immersion time and analyze the factors that play important roles in the oxidation process in LBE/lead. It is shown that there is a significant difference between the oxide formed in liquid lead alloys and in gases, including the oxide-layer structure. To generate a stable protective oxide layer on steel surfaces in LBE, the long-term corrosion effect, the supply of oxygen, and the penetration of the liquid metal into the structural materials or oxide layers must be taken into account. (authors)

Jinsuo Zhang; Ning Li [Los Alamos National Laboratory, 1619 Central Avenue, MS A117 Los Alamos NM 87545 (United States)

2006-07-01

59

Surface Passivation of Silicon Solar Cells Using Plasma Silicon Nitride Films and Thermal Silicon Oxide\\/Plasma Silicon Nitride Stacks  

Microsoft Academic Search

A comparison of the surface passivation achieved for PECVD silicon nitride films and thermal silicon oxide\\/silicon nitride stacks is presented in this work. It is demonstrated that both techniques give excellent surface passivation on: (i) low-resistivity (1?cm and 0.3?cm) p-silicon substrates and (ii) n+-diffused solar cell emitters for sheet resistances ranging from 30-430?\\/ . Both passivation schemes have been used

M. J. Kerr; J. Schmidt; A. Cuevas

60

Photoluminescence of silicon nanocrystals embedded in silicon oxide.  

PubMed

The bonding structure and the optical properties of silicon-rich silicon oxide films which were prepared using plasma-enhanced chemical vapor deposition (PECVD) with thermal oxidation were studied in detail. The composition and bonding structures were explored using X-ray photoelectron spectroscopy (XPS). The luminescent properties were studied using Raman spectroscopy and photoluminescence (PL) measurements. Results show that high-temperature (approximately 1000 degrees C) annealing of as-deposited Si-rich silicon oxide gives rise to phase separation and formation of crystalline Si phases in the oxide films. Upon high temperature annealing, the PL (550-900 nm) intensity was significantly reduced in stoichiometric oxide or in low Si-content (prepared with [N2O]/[SiH4] gas flow ratio > 2.5) films whereas an opposite trend was found in higher Si-rich samples. Particularly, for the red band (650 nm) and the infrared band (750 nm), the PL intensity was significantly enhanced by annealing slightly Si-rich samples ([N2O] / [SiH4] = 2.5) at 1100 degrees C. This observation was explained by the formation of Si nanocrystallites via phase separation reaction and the removal of defect-related absorption centers during annealing. PMID:19441504

Wong, C K; Wong, Hei; Filip, V

2009-02-01

61

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

PubMed

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

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

2011-01-01

62

Silicon nitride cantilevers with oxidation-sharpened silicon tips for atomic force microscopy  

Microsoft Academic Search

High-resolution atomic force microscopy (AFM) of soft or fragile samples requires a cantilever with a low spring constant and a sharp tip. We have developed a novel process for making such cantilevers from silicon nitride with oxidation-sharpened silicon tips. First, we made and sharpened silicon tips on a silicon wafer. Next, we deposited a thin film of silicon nitride over

Randal J. Grow; Stephen C. Minne; Scott R. Manalis; Calvin F. Quate

2002-01-01

63

Phase evolution of magnetite nanocrystals on oxide supports via template-free bismuth ferrite precursor approach  

NASA Astrophysics Data System (ADS)

This report investigates the phase evolution pathway of magnetite nanocrystal synthesis on oxide-supported substrates. A template-free phase separation approach, which exploits the thermodynamic instability of ternary perovskite BiFeO3 and inherent volatility of bismuth oxide in low oxygen pressure and high temperature is presented. The formation of an intermediate hematite nanocrystal phase is found as a key step that controls the eventual size and morphology of the magnetite nanocrystals. X-ray absorption spectra measurements and X-ray magnetic circular dichroism confirm that the spectral fingerprints of the magnetite nanocrystals match with that of bulk crystals. Magnetic measurements show that magnetic anisotropy is directly attributed to the nanocrystal morphology.

Cheung, Jeffrey; Bogle, Kashinath; Cheng, Xuan; Sullaphen, Jivika; Kuo, Chang-Yang; Chen, Ying-Jiun; Lin, Hong-Ji; Chen, Chien-Te; Yang, Jan-Chi; Chu, Ying-Hao; Valanoor, Nagarajan

2012-11-01

64

Two step oxidation processes in silicon  

NASA Astrophysics Data System (ADS)

We have studied dielectric breakdown characteristics of this (approx. 10nm) silicon dioxide films grown on silicon under the following conditions: (A) Standard oxidation process with the oxides grown at 800C; (B) Annealing the oxides at 1000C in argon for 30 minutes after going through step (A); (C) Two - Step oxidation, i.e., 800C - 4 nm followed by 1000C anneal for 30 minutes in argon and a final oxidation, at 8000C to grow a total of 9 nm; (D) Growth of oxide at 1000C. The results show that (B) and (C) have comparable dielectric breakdown strengths, indicating that high temperature annealing has the same advantage as the two-step oxidation in improving the dielectric strength of silicon dioxide. High resolution transmission electron micrographs show that the interface structures are fairly similar in all the cases indicating that the interface smoothness as observed in the transmission electron micrographs are not directly responsible for the dielectric breakdown. Our observations of the protrusions at the Si/SiO2 interface may also possibly explain the high values of the refractive index which has earlier been attributed to a monolayer of nonstoichiometric SIOX at the SI/SIO2 interface.

Ravindra, N. M.; Fathy, Dariush; Narayan, J.; Srivastava, J. K.; Irene, E. A.

1986-07-01

65

Thermodynamic stability of binary oxides in contact With silicon  

Microsoft Academic Search

Using tabulated thermodynamic data, a comprehensive investigation of the thermodynamic stability of binary oxides in contact with silicon at 1000 K was conducted. Reactions between silicon and each binary oxide at 1000 K, including those involving ternary phases, were considered. Sufficient data exists to conclude that all binary oxides except the following are thermodynamically unstable in contact with silicon at

K. J. Hubbard; D. G. Schlom

1996-01-01

66

Effect of oxygen sublattice ordering on interstitial transport mechanism and conductivity activation energies in phase-stabilized cubic bismuth oxides  

Microsoft Academic Search

Bismuth oxide doped with isovalent rare earth cations retains the high temperature defective fluorite structure upon cooling down to room temperature. However, these doped materials undergo an orderdisorder transition of the oxygen sublattice at about 600C. When annealed at temperatures less than the transition temperature, the oxygen sublattice continues to order, and consequently oxygen ion conductivity undergoes a decay. However,

Sai Boyapati; Eric D Wachsman; Naixiong Jiang

2001-01-01

67

Tin oxide microsensors on thin silicon membranes  

NASA Astrophysics Data System (ADS)

Tin oxide based microsensors with integrated polysilicon heaters were fabricated on thin silicon membranes generated by anisotropic wet chemical etching using ethylene diamine pyrocatechol as the etchant. Good thermal isolation and lower power consumption were achieved. The sensing elements, tin oxide thin films, were prepared either by sputter deposition or by metallo-organic deposition. The completed microsensors showed good response to alcohol vapor and good stability of the integrated polysilicon heaters.

Chang, Shih-Chia; Hicks, David B.

68

FTIR study of fluorinated silicon oxide film  

Microsoft Academic Search

Fluorinated silicon oxide (SiOF) films were prepared by plasma enhanced chemical vapour deposition (PECVD) and studied by FTIR spectroscopic measurements. As fluorination dosage increased, the band intensity of the Si - F stretching mode was observed to increase but the peak frequency and band width remained unchanged. The Si - O vibrational bands were found to increase in frequency and

Bog-Gi Kim; Seung-Youl Kang; Jong-Jean Kim

1997-01-01

69

Epitaxial Growth of Strontium Bismuth Tantalate/Niobate of Buffered Magnesium Oxide Substrates  

SciTech Connect

Epitaxial films of strontium bismuth tantalate (SrBi{sub 2}Ta{sub 2}O{sub 9}, SBT) and strontium bismuth niobate (SrBi{sub 2}Nb{sub 2}O{sub 9}, SBN) were grown using solution deposition techniques on magnesium oxide (MgO) substrates buffered with a 100 nm layer of lanthanum manganate (LaMnO{sub 3}, LMO). Film structure and texture analyses were carried out using x-ray diffraction. Theta-2theta diffraction patterns were consistent with a c-axis aligned structure for both the buffer layer and the solution deposited films. Theta-2 theta scans revealed (001){sub SBT, SBN}//(001) LMO epitaxial relationships between the solution deposited films and the buffer layer. A pole figure about the SBT, SBN (115) reflection indicated a single in-plane epitaxy. Film quality was assessed using {omega} and {phi} scans. Nuclear Magnetic Resonance ({sup 13}C) was used to characterized the methoxy-ethoxide solutions used for the deposition of the SBN and SBT films.

Thomas, George H [ORNL; Morrell, Johathan [University of Tennessee, Knoxville (UTK); Aytug, Tolga [ORNL; Xue, Ziling {nmn} [ORNL; Beach, David B [ORNL

2006-01-01

70

Study of humidity properties of Zinc Oxide modified Porous Silicon  

Microsoft Academic Search

In this paper, we discussed the humidity sensing behavior of Zinc Oxide modified porous silicon (ZnO\\/PS) composite structure. The porous silicon substrates were prepared by the electrochemical etching process first. Then, by sol-gel technique, it is possible to obtain a uniform Zinc Oxide films on the porous silicon substrates. The electrical conductivities of the porous silicon and Zinc Oxide modified

Tao Jiang; Xiaofeng Zhou; Jian Zhang; Jianzhong Zhu; Xinxin Li; Tie Li

2006-01-01

71

Genotoxic effects of Bismuth (III) oxide nanoparticles by Allium and Comet assay.  

PubMed

Genotoxic effects of Bismuth (III) oxide nanoparticles (BONPs) were investigated on the root cells of Allium cepa by Allium and Comet assay. A. cepa roots were treated with the aqueous dispersions of BONPs at five different concentrations (12.5, 25, 50, 75, and 100ppm) for 4h. Exposure of BONPs significantly increased mitotic index (MI) except 12.5ppm, total chromosomal aberrations (CAs) in Allium test. While stickiness chromosome laggards, disturbed anaphase-telophase and anaphase bridges were observed in anaphase-telophase cells, pro-metaphase and c-metaphase in other cells. A significant increase in DNA damage was also observed at all concentrations of BONPs except 12.5ppm by Comet assay. The results were also analyzed statistically by using SPSS for Windows; Duncan's multiple range test was performed. These results indicate that BONPs exhibit genotoxic activity in A. cepa root meristematic cells. PMID:23790828

Liman, Recep

2013-06-20

72

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

SciTech Connect

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).

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

1994-01-01

73

Spectroscopic and microscopic study of the corrosion of ironsilicon steel by leadbismuth eutectic (LBE) at elevated temperatures  

Microsoft Academic Search

The performance of ironsilica alloys with different silicon composition was evaluated after exposure to an isothermal bath of leadbismuth eutectic (LBE). Four alloys were evaluated: pure iron, Fe1.24%Si, Fe2.55%Si and Fe3.82%Si. The samples were exposed to LBE in a dynamic corrosion cell for periods from 700 to 1000h at a temperature of 550C. After exposure, the thickness and composition of

Allen L. Johnson; Eric P. Loewen; Thao T. Ho; Dan Koury; Brian Hosterman; Umar Younas; Jenny Welch; John W. Farley

2006-01-01

74

Electrically tailored resistance switching in silicon oxide  

NASA Astrophysics Data System (ADS)

Resistive switching in a metal-free silicon-based material offers a compelling alternative to existing metal oxide-based resistive RAM (ReRAM) devices, both in terms of ease of fabrication and of enhanced device performance. We report a study of resistive switching in devices consisting of non-stoichiometric silicon-rich silicon dioxide thin films. Our devices exhibit multi-level switching and analogue modulation of resistance as well as standard two-level switching. We demonstrate different operational modes that make it possible to dynamically adjust device properties, in particular two highly desirable properties: nonlinearity and self-rectification. This can potentially enable high levels of device integration in passive crossbar arrays without causing the problem of leakage currents in common line semi-selected devices. Aspects of conduction and switching mechanisms are discussed, and scanning tunnelling microscopy (STM) measurements provide a more detailed insight into both the location and the dimensions of the conductive filaments.

Mehonic, Adnan; Cueff, Sbastien; Wojdak, Maciej; Hudziak, Stephen; Labb, Christophe; Rizk, Richard; Kenyon, Anthony J.

2012-11-01

75

Bismuth Subsalicylate  

MedlinePLUS

Pink Bismuth ... Bismuth subsalicylate is used to treat diarrhea, heartburn, and upset stomach in adults and children 12 years of age and older. Bismuth subsalicylate is in a class of medications called ...

76

Effect of bismuth oxide on the phase composition and magnetic properties of the 12Fe 2 O 3 3BaO 2CoO system  

Microsoft Academic Search

A study was made of the effect of the addition of the low-melting-point bismuth oxide on the phase composition and magnetic properties of the 12Fe2O33BaOCoO system. The optimum Bi2O3 concentration, at which the key magnetic properties attain their maxima, is 1 wt.%. The influence exerted by bismuth oxide on the magnetic properties of the ferrite is associated with qualitative and

E. A. Kuchinskaya; A. G. Titenko; V. P. Pashchenko; Z. P. Morozova; I. F. Klochai; S. E. Shaporenko

1977-01-01

77

Non-oxide (Silicon Carbide) Fibers  

Microsoft Academic Search

Non-oxide ceramic fibers are being considered for many applications, but are currently being developed and produced primarily\\u000a as continuous-length structural reinforcement for ceramic matrix composites (CMC). Since only those fiber types with compositions\\u000a based on silicon carbide (SiC) have demonstrated their general applicability for this application, this chapter focuses on\\u000a commercially available SiC-based ceramic fiber types of current interest for

James A. DiCarlo; Hee-Mann Yun

78

Chemical and photochemical functionality of the first molecular bismuth vanadium oxide.  

PubMed

Anionic metal oxide clusters, so-called polyoxometalates, can be developed as molecular model compounds to mimic the chemical and photochemical reactivity of solid-state metal oxides on the molecular level. Inspired by the well-known visible-light photocatalyst BiVO(4), the first molecular bismuth vanadium oxide has been synthesized to investigate the chemical and photochemical similarities between the solid-state and molecular compounds. The cluster H(3)[(Bi(dmso)(3))(4)V(13)O(40)]ca. 4 DMSO was obtained from simple precursors in almost quantitative yield. Structural analysis showed that the cluster shell is based on the unusual all-vanadium ?-Keggin framework [?-V(12)O(40)](15-), which is stabilized by coordination of four Bi(III) centers. The acidic character of the three cluster protons was demonstrated by titration studies. The cluster shows promising photocatalytic properties in visible-light photooxidation reactions and has high activity (turnover number >1200), high quantum yield (?=7.6 %), and good recyclability, which make it a promising first example of a new class of heterometallic polyoxometalates. PMID:22829485

Tucher, Johannes; Nye, Leanne C; Ivanovic-Burmazovic, Ivana; Notarnicola, Antonio; Streb, Carsten

2012-07-24

79

Atomic and Electronic Structures of Traps in Silicon Oxide and Silicon Oxynitride  

Microsoft Academic Search

Silicon oxide (SiO2) and silicon oxynitride (SiOxNy) are two key dielectrics used in silicon devices. The excellent interface properties of these dielectrics with silicon have enabled the tremendous advancement of metal-oxide-semiconductor (MOS) technology. However, these dielectrics are still found to have pronounced amount of localized states which act as electron or hole traps and lead to the performance and reliability

Vladimir Gritsenko; Hei Wong

2011-01-01

80

Lateral epitaxial growth of germanium on silicon oxide  

SciTech Connect

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.

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

81

A Zinc Oxide modified Porous Silicon humidity sensor  

Microsoft Academic Search

In this paper, a relative humidity sensor based on zinc oxide modified porous silicon was discussed. The porous silicon was prepared by electrochemical etching process first. Then the sol-gel precursor of Zinc Oxide was applied to the PS substrates and annealed at 450 degC. By this technique, it is possible to obtain a uniform zinc oxide film on the porous

Tao Jiang; Xiaofeng Zhou; Jian Zhang; Yanling Shi; Tianxing Luo

2006-01-01

82

Effects of addition of bismuth oxide and glass on the properties of lithium ferrite for ferrimagnetic pastes  

Microsoft Academic Search

Lithium ferrite, Li0.5Fe2.5O4, has been prepared by decomposition of organometallic complexes at 800 C, and the optimization of heating schedule for conversion into ferrite has been studied. The effects of addition of glass, essential for adhesion of the ferrite film to alumina substrates, and bismuth oxide, as a sintering aid, on the properties and densification of lithium ferrite have been

Mangalkanti Paria; CHINMAY K. MAITIt; N. B. CHAKRABARTIt

1982-01-01

83

Fouling Study of Silicon Oxide Pores Exposed to Tap Water  

SciTech Connect

We report on the fouling of Focused Ion Beam (FIB)-fabricated silicon oxide nanopores after exposure to tap water for two weeks. Pore clogging was monitored by Scanning Electron Microscopy (SEM) on both bare silicon oxide and chemically functionalized nanopores. While fouling occurred on hydrophilic silicon oxide pore walls, the hydrophobic nature of alkane chains prevented clogging on the chemically functionalized pore walls. These results have implications for nanopore sensing platform design.

Nilsson, J.; Bourcier, W.L.; Lee, J.R.I.; Letant, S.E.; /LLNL, Livermore

2007-07-12

84

Surface chemistry dependence of native oxidation formation on silicon nanocrystals  

Microsoft Academic Search

The growth of silicon oxide on bare and SF6-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 CabreraMott mechanism, and the measured data are well fitted

R. W. Liptak; U. Kortshagen; S. A. Campbell

2009-01-01

85

Surface chemistry dependence of native oxidation formation on silicon nanocrystals  

Microsoft Academic Search

The growth of silicon oxide on bare and SF6-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

R. W. Liptak; U. Kortshagen; S. A. Campbell

2009-01-01

86

FTIR study of fluorinated silicon oxide film  

NASA Astrophysics Data System (ADS)

Fluorinated silicon oxide (SiOF) films were prepared by plasma enhanced chemical vapour deposition (PECVD) and studied by FTIR spectroscopic measurements. As fluorination dosage increased, the band intensity of the Si - F stretching mode was observed to increase but the peak frequency and band width remained unchanged. The Si - O vibrational bands were found to increase in frequency and decrease in band width. The Si - O asymmetric stretching band was analysed. It was found that the average bond angle of Si - O - Si bond increased but the distribution of the bond angles decreased in width as fluorination dosage was increased.

Kim, Bog-Gi; Kang, Seung-Youl; Kim, Jong-Jean

1997-06-01

87

ReaxFF SiO Reactive Force Field for Silicon and Silicon Oxide Systems  

Microsoft Academic Search

To predict the structures, properties, and chemistry of materials involving silicon and silicon oxides; interfaces between these materials; and hydrolysis of such systems, we have developed the ReaxFFSiO, reactive force field. The parameters for this force field were obtained from fitting to the results of quantum chemical (QC) calculations on the structures and energy barriers for a number of silicon

Adri C. T. van Duin; Alejandro Strachan; Shannon Stewman; Qingsong Zhang; Xin Xu; William A. Goddard

2003-01-01

88

Magnetic and electrical properties of nickel-zinc ferrites doped with bismuth oxide  

Microsoft Academic Search

Bismuth-substituted nickel-zinc ferrites have been synthesized by a solution route in the composition range Ni0.5Zn0.5BixFe2.0?xO4, with 0 ? x ? 0.2. X-ray diffraction data indicate that bismuth most likely exists in the Bi5+ state within the spinel structure. The saturation magnetization is found to decrease as the bismuth concentration is enhanced. This can be explained on the basis of two

M. Pal; P. Brahma; D. Chakravorty

1996-01-01

89

Progress in bismuth vanadate photoanodes for use in solar water oxidation.  

PubMed

Harvesting energy directly from sunlight as nature accomplishes through photosynthesis is a very attractive and desirable way to solve the energy challenge. Many efforts have been made to find appropriate materials and systems that can utilize solar energy to produce chemical fuels. One of the most viable options is the construction of a photoelectrochemical cell that can reduce water to H(2) or CO(2) to carbon-based molecules. Bismuth vanadate (BiVO(4)) has recently emerged as a promising material for use as a photoanode that oxidizes water to O(2) in these cells. Significant advancement in the understanding and construction of efficient BiVO(4)-based photoanode systems has been made within a short period of time owing to various newly developed ideas and approaches. In this review, the crystal and electronic structures that are closely related to the photoelectrochemical properties of BiVO(4) are described first, and the photoelectrochemical properties and limitations of BiVO(4) are examined. Subsequently, the latest efforts toward addressing these limitations in order to improve the performances of BiVO(4)-based photoanodes are discussed. These efforts include morphology control, formation of composite structures, composition tuning, and coupling oxygen evolution catalysts. The discussions and insights provided in this review reflect the most recent approaches and directions for general photoelectrode developments and they will be directly applicable for the understanding and improvement of other photoelectrode systems. PMID:23092995

Park, Yiseul; McDonald, Kenneth J; Choi, Kyoung-Shin

2012-10-23

90

Easy synthesis of bismuth iron oxide nanoparticles as photocatalyst for solar hydrogen generation from water  

NASA Astrophysics Data System (ADS)

In this study, high purity bismuth iron oxide (BiFeO3/BFO) nanoparticles of size 50-80 nm have been successfully synthesized by a simple sol-gel method using urea and polyvinyl alcohol at low temperature. X-ray diffraction (XRD) measurement is used to optimize the synthetic process to get highly crystalline and pure phase material. Diffuse reflectance ultraviolet-visible (DRUV-Vis) spectrum indicates that the absorption cut-off wavelength of the nanoparticles is about 620 nm, corresponding to an energy band gap of 2.1 eV. Compared to BaTiO3, BFO has a better degradation of methyl orange under light radiation. Also, photocatalytic tests prove this material to be efficient towards water splitting under simulated solar light to generate hydrogen. The simple synthetic methodology adopted in this paper will be useful in developing low-cost semiconductor materials as effective photocatalysts for hydrogen generation. Photocatalytic tests followed by gas chromatography (GC) analyses show that BiFeO3 generates three times more hydrogen than commercial titania P25 catalyst under the same experimental conditions.

Deng, Jinyi

91

Electrically tailored resistance switching in silicon oxide.  

PubMed

Resistive switching in a metal-free silicon-based material offers a compelling alternative to existing metal oxide-based resistive RAM (ReRAM) devices, both in terms of ease of fabrication and of enhanced device performance. We report a study of resistive switching in devices consisting of non-stoichiometric silicon-rich silicon dioxide thin films. Our devices exhibit multi-level switching and analogue modulation of resistance as well as standard two-level switching. We demonstrate different operational modes that make it possible to dynamically adjust device properties, in particular two highly desirable properties: nonlinearity and self-rectification. This can potentially enable high levels of device integration in passive crossbar arrays without causing the problem of leakage currents in common line semi-selected devices. Aspects of conduction and switching mechanisms are discussed, and scanning tunnelling microscopy (STM) measurements provide a more detailed insight into both the location and the dimensions of the conductive filaments. PMID:23064085

Mehonic, Adnan; Cueff, Sbastien; Wojdak, Maciej; Hudziak, Stephen; Labb, Christophe; Rizk, Richard; Kenyon, Anthony J

2012-10-12

92

Structural, electrical and magnetic measurements on oxide layers grown on 316L exposed to liquid lead-bismuth eutectic  

NASA Astrophysics Data System (ADS)

Fast reactors and spallation neutron sources may use lead-bismuth eutectic (LBE) as a coolant. Its physical, chemical, and irradiation properties make it a safe coolant compared to Na cooled designs. However, LBE is a corrosive medium for most steels and container materials. The present study was performed to evaluate the corrosion behavior of the austenitic steel 316L (in two different delivery states). Detailed atomic force microscopy, magnetic force microscopy, conductive atomic force microscopy, and scanning transmission electron microscopy analyses have been performed on the oxide layers to get a better understanding of the corrosion and oxidation mechanisms of austenitic and ferritic/martensitic stainless steel exposed to LBE. The oxide scale formed on the annealed 316L material consisted of multiple layers with different compositions, structures, and properties. The innermost oxide layer maintained the grain structure of what used to be the bulk steel material and shows two phases, while the outermost oxide layer possessed a columnar grain structure.

Hosemann, Peter; Hofer, Christian; Hlawacek, Gregor; Li, Ning; Maloy, Stuart A.; Teichert, Christian

2012-02-01

93

Local anodic oxidation on dodecyl terminated silicon(100)  

NASA Astrophysics Data System (ADS)

Nanolithography by local oxidation induced by scanning probe microscopy on dodecyl terminated silicon(100) has been carried out under ambient conditions and controlled humidity. A linear increase in the height of the formed oxide with the applied voltage and a logarithmic decrease with increasing writing velocity has been found. The amount of formed oxide could be described by a biexponential model indicating that a direct oxidation process dominates the oxidation while an indirect oxidation process is less pronounced compared to the oxidation of hydrogen terminated silicon [J.A. Dagata, F. Perez-Murano, C. Martin, H. Kuramochi, H. Yokoyama, J. Appl. Phys. 96 (2004) 2386].

Graaf, Harald; Baumgrtel, Thomas; Vieluf, Maik; von Borczyskowski, Christian

2008-10-01

94

Optimized amorphous silicon oxide buffer layers for silicon heterojunction solar cells with microcrystalline silicon oxide contact layers  

NASA Astrophysics Data System (ADS)

We report on the systematic optimization of the intrinsic amorphous silicon oxide buffer layer in interplay with doped microcrystalline silicon oxide contact layers for silicon heterojunction solar cells using all silicon oxide based functional layers on flat p-type float-zone wafers. While the surface passivation quality is comparably good within a wide range of low oxygen contents, the optical band gap increases and the dark conductivity decreases with increasing oxygen content, giving rise to an inevitable trade-off between optical transparency and electrical conductivity. On the cell level, fill factor FF and short circuit current density Jsc losses compete with the open circuit voltage Voc gains resulting from a thickness increase of the front buffer layers, whereas Jsc and Voc gains compete with FF losses resulting from increasing thickness of the rear buffer layers. We obtained the highest active area efficiency of ?act = 18.5% with Voc = 664 mV, Jsc = 35.7 mA/cm2, and FF = 78.0% using 4 nm front and 8 nm rear buffer layer with an oxygen content of 5%.

Ding, Kaining; Aeberhard, Urs; Finger, Friedhelm; Rau, Uwe

2013-04-01

95

Investigating the use of bismuth(V) for the oxidation and subsequent solvent extraction of americium(VI)  

SciTech Connect

The separation of Am from Cm and the lanthanides is still one of the most complex separations facing analytical chemistry, as well as any proposed advanced fuel cycle. Current research is focused on the oxidation of americium for its selective separation from the trivalent lanthanides and curium. We have already successfully demonstrated that Am oxidized to the hexavalent state using sodium bismuthate at room temperature can be extracted into 30% TBP/dodecane. Its behavior has been demonstrated to be analogous to that of hexavalent uranyl, neptunyl, and plutonyl ions. Using UV-visible spectrophotometry, the mechanism of the oxidation with sodium bismuthate has been probed to identify if it is a suitable reagent for deployment in solvent extraction systems. It has been identified that 97% of the Am is oxidized within the first 5 minutes. Significantly longer periods of time are required to obtain a solution containing greater than 50% Am(VI) limiting the use of Bi(V) for process applications. (authors)

Martin, L.R.; Mincher, B.J.; Schmitt, N.C. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415-2208 (United States)

2008-07-01

96

Far-infrared stimulated emission from optically excited bismuth donors in silicon  

NASA Astrophysics Data System (ADS)

Far-infrared stimulated emission from optically pumped neutral Bi donors in silicon has been obtained. Lasing with wavelengths of 52.2 and 48.6 mum from the intra-center 2pplus-or-minus[right arrow]1s(E:Gamma]8),1s(T2:[Gamma8) transitions has been realized under CO2 laser pumping. The population inversion mechanism is based on fast optical-phonon-assisted relaxation from the 2p0 and 2s excited states directly to the ground 1s(A) state leading to relatively small population in the intermediate 1s(E), 1s(T2) excited states.

Pavlov, S. G.; Hubers, H.-W.; Rummeli, M. H.; Zhukavin, R. Kh.; Orlova, E. E.; Shastin, V. N.; Riemann, H.

2002-06-01

97

The Study of Defects in Bismuth Germanium Oxide Using Phonon Echoes and Other Techniques  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Four different experimental techniques have been used to probe defect states in piezoelectric bismuth germanium oxide (BGO) in its nominally pure form and when it is doped with a range of chemical impurities. In particular a novel technique has been developed to determine the energy distribution of shallow traps (<=30meV) in piezoelectric semiconductors. The method is based upon electric field enhanced tunnelling from defect states by the application of a high power microwave pulse (9GHz) at low temperatures (~1.3K). An acoustic wave is piezoelectrically coupled to the tunnelling process, and the non-linearity of the tunnelling probability mixes the phonons with the microwave field. This produces a free carrier density containing a static Fourier component varying on the scale of the acoustic wavelength. Subsequent relaxation of the carriers into the traps produces a charge grating which can be maintained for long periods at low temperatures. The application of a third microwave pulse causes the grating to generate a backward acoustic wave with an amplitude that is a direct measure of the defect ionisation energy. Field induced decay and thermal decay of the charge grating yields information on the distribution of trapping states and thermal relaxation times. Energy distributions for both BGO:Zn and BGO:Bi have been obtained. Further information about the defect structures in these materials has been deduced from complementary experiments using photoconductive techniques, thermally stimulated currents and parametric phonon echo generation. There is some evidence to suggest that a common defect is responsible for the observations made with all of the techniques used.

Terry, Ian

98

Sensitized broadband near-infrared luminescence from bismuth-doped silicon-rich silica films.  

PubMed

Developing Si compatible optical sources has attracted a great deal of attention owing to the potential for forming inexpensive, monolithic Si-based integrated devices. In this Letter, we show that ultra broadband near-IR (NIR) luminescence in the optical telecommunication window of silica optical fibers was obtained for Bi-doped silicon-rich silica films prepared by a co-sputtering method. Without excess Si, i.e., Bi-doped pure silica films, no luminescence was observed in the NIR range. A broad Bi-related NIR photoluminescence appears when excess Si was doped in the Bi-doped silica. The luminescence properties depended strongly on the amount of excess Si and the annealing temperature. Photoluminescence results suggest that excess Si acts as an agent to activate Bi NIR luminescence centers and also as an energy donor to transfer excitation energy to the centers. It is believed that this peculiar structure might find some important applications in Si photonics. PMID:22048371

Miwa, Yuji; Sun, Hong-Tao; Imakita, Kenji; Fujii, Minoru; Teng, Yu; Qiu, Jianrong; Sakka, Yoshio; Hayashi, Shinji

2011-11-01

99

[Photoluminescence from Er-doped silicon-rich silicon oxide film and Er-doped silicon-rich silicon nitride film and its annealing behavior].  

PubMed

Room temperature photoluminescence (PL) with a peak at 1.54 microns was observed from silicon oxide, silicon-rich silicon oxide, silicon nitride and silicon-rich silicon nitride films, all doped with Er and grown by the magnetron sputtering technique. To determine the optimum annealing temperature for the 1.54 microns PL, these films were annealed in the range of 600-1,100 degrees C with an interval of 100 degrees C. Among these four types of films annealed at an identical temperature, the intensity of 1.54 microns PL peak of the Er-doped silicon-rich silicon oxide film was always the strongest one, which arrived at a maximum in 800 degrees C annealing. A 1.38 microns PL band was also observed in each of these four types of films, and which in the silicon-rich silicon oxide or silicon-rich silicon nitride films was found to be correlated with the 1.54 microns PL band in intensity. PMID:12958888

Yuan, F C; Ran, G Z; Chen, Y; Zhang, B R; Qiao, Y P; Fu, J S; Qin, G G; Ma, Z C; Zong, W H

2001-12-01

100

Magnetic isotope and magnetic field effects on the silicon oxidation  

NASA Astrophysics Data System (ADS)

Silicon oxidation by oxygen depends on the magnetic field and exhibits isotope effect: silicon atoms 29Si with magnetic nuclei are oxidized twice as fast as atoms 28Si and 30Si with nonmagnetic nuclei. Both effects certify that the oxidation is a spin selective reaction in which radical pairs participate. The dominating oxidizing species are oxygen molecules in triplet spin state which generate triplet radical pairs. Zeeman interaction and hyperfine coupling with 29Si nuclei in these pairs stimulate triplet-singlet spin conversion and transform triplet pairs into the reactive singlet ones. The subsequent spin allowed reactions in the latter result in the oxidation products.

Koplak, Oksana; Morgunov, Roman; Buchachenko, Anatoly

2013-02-01

101

Optical characterization of nanocrystals in silicon rich oxide superlattices and porous silicon  

Microsoft Academic Search

We propose to analyze ellipsometry data by using effective medium approximation (EMA) models. Thanks to EMA, having nanocrystalline reference dielectric functions and generalized critical point (GCP) model the physical parameters of two series of samples containing silicon nanocrystals, i.e. silicon rich oxide (SRO) superlattices and porous silicon layers (PSL), have been determined. The superlattices, consisting of ten SRO\\/SiO2 layer pairs,

E. Agocs; P. Petrik; S. Milita; L. Vanzetti; S. Gardelis; A. G. Nassiopoulou; G. Pucker; R. Balboni; M. Fried

2011-01-01

102

Nanoscale oxidation of silicon microring resonators  

Microsoft Academic Search

* Email: smookherjea@ucsd.edu Abstract: The resonance frequency of a silicon microring was permanently blue-shifted with 1.2 GHz resolution over more than 350 GHz, a full free-spectral-range, by electrochemically changing the waveguide core (silicon) to the cladding (silicon dioxide) material. ?2011 Optical Society of America Silicon microring devices are sensitively affected by nanoscale disorder, e.g., few nanometer variations in the width

Yiran Shen; Shayan Mookherjea

2011-01-01

103

Improved Retention Characteristic in Polycrystalline Silicon--Oxide--Hafnium Oxide--Oxide--Silicon-Type Nonvolatile Memory with Robust Tunnel Oxynitride  

NASA Astrophysics Data System (ADS)

In this paper, we present a simple novel process for forming a robust and reliable oxynitride dielectric with a high nitrogen content. It is highly suitable for n-channel metal--oxide--semiconductor field-effect transistor (nMOSFETs) and polycrystalline silicon--oxide--hafnium oxide--oxide--silicon (SOHOS)-type memory applications. The proposed approach is realized by using chemical oxide with ammonia (NH3) nitridation followed by reoxidation with oxygen (O2). The novel oxynitride process is not only compatible with the standard complementary metal--oxide--semiconductor (CMOS) process, but also can ensure the improvement of flash memory with low-cost manufacturing. The characteristics of nMOSFETs and SOHOS-type nonvolatile memories (NVMs) with a robust oxynitride as a gate oxide or tunnel oxide are studied to demonstrate their advantages such as the retardation of the stress-induced trap generation during constant-voltage stress (CVS), the program/erase behaviors, cycling endurance, and data retention. The results indicate that the proposed robust oxynitride is suitable for future nonvolatile flash memory technology application.

Hsieh, Chih Ren; Lai, Chiung Hui; Lin, Bo Chun; Zheng, Yuan Kai; Lou, Jen Chung; Lin, Gray

2011-03-01

104

Microstructural evolution in high oxygen fugacity processed bismuth strontium calcium copper oxide  

NASA Astrophysics Data System (ADS)

A decomposition/reformation process that uses a high oxygen fugacity (2 MPa) heat treatment followed by low oxygen fugacity (<1 MPa) annealing was applied to silver-sheathed Bisb2Srsb2CaCusb2Osb{8delta} (Bi-2212) tapes. The rate at which the Bi-2212 phase reforms was studied using X-ray diffractometry and image analyses. The kinetic data was fitted to an Avrami-type equation and was found to be consistent with that predicted for diffusion-controlled growth of plate-like grains. The effect of varying the oxygen fugacity during reformation annealing was also studied and the rate of Bi-2212 phase formation slowed considerably with increasing oxygen fugacity. The rate of oxygen exsolution from the core is a key parameter for the overall transformation kinetics. Two of the decomposition products produced by high-fOsb2 processing of the Bi-2212 compound are a copper-free alkaline-earth bismuthate (a Bisb9Srsb{11}Casb5Osb{x}-type) and CuO. Blended mixtures of these two compounds were used to form two-powder reaction couples used to study Bi-2212 phase formation. Samples were annealed in flowing oxygen at temperatures below the Bi-2212 solidus. The formation of apparent Bi-2212/Bi-2201 intergrowths along with some alkaline-earth cuprate phases were detected. The 14:24-type alkaline-earth cuprate phase was formed in fine CuO powder couples but not in couples containing large CuO particles. The reaction leading to Bi-2212 phase formation was confirmed to be solid-state at temperatures below 875spC. The development of c-axis grain alignment in high-fOsb2 decomposed Bi-2212 tapes that were reformed with low-fOsb2 annealing was studied. Such processing can produce enhanced 00l grain alignment and the evolution of this texture was examined in tapes at intermediate points in the reformation process. Some of the mechanisms associated with texture development in melt-processed tapes were found to be inadequate for describing the alignment in high-fOsb2 processed Bi-2212 grains. Microstructural texture was found to develop uniformly throughout the thickness of the oxide core and a number of factors that could contribute to this behavior were identified. Critical current density (Jsbc) measurements were made on a number of tapes and intermediate mechanical deformation (pressing) operations were found to be a possible approach for enhancing Jsbc in tapes processed with high-fOsb2 heat treatments.

Gannon, John J., Jr.

105

Effect of Silicon Wafer In Situ Cleaning on the Chemical Structure of Ultrathin Silicon Oxide Film  

NASA Astrophysics Data System (ADS)

The effect of silicon wafer in situ cleaning on the chemical structures of thermally grown silicon oxide films was studied by X-ray photoelectron spectroscopy and scanning tunneling microscopy. After the silicon wafer in situ cleaning was performed by the decomposition of native oxides in high vacuum, the nearly 1.6-nm-thick thermal oxides were formed in dry oxygen at 800C. If the heating time for the decomposition of native oxides was too short, intermediate states transformed from native oxides were found to remain on the surface of the oxide films. On the other hand, if the heating time was too long, the amount of intermediate states at the interface was found to increase as a result of the increase in interface roughness. The optimum condition for in situ cleaning is heating at 900C for 30 minutes in high vacuum.

Terada, Naozumi; Ogawa, Hiroki; Moriki, Kazunori; Teramoto, Akinobu; Makihara, Koji; Morita, Mizuho; Ohmi, Tadahiro; Hattori, Takeo

1991-12-01

106

The Electrochemical Oxidation of Silicon and Formation of Porous Silicon in Acetonitrile  

Microsoft Academic Search

The photoelectrochemical oxidation and dissolution of silicon has been investigated in the absence of water and oxygen. The etch rate and photocurrent for n-St in an anhydrous, HF-acetonitrile solution were directly proportional to light intensity. Four electrons were transferred per silicon oxidized, with a quantum yield greater than 3.3 due to electron 2 injection. The anodic dissolution of p-St, as

Eric K. Propst; Paul A. Kohl

1994-01-01

107

High-pressure deuterium annealing for improving the reliability characteristics of silicon-oxide-nitride-oxide-silicon nonvolatile memory devices  

Microsoft Academic Search

We report the effects of high-pressure deuterium postmetallization annealing on the reliability characteristics of silicon-oxide-nitride-oxide-silicon nonvolatile memory devices. Compared with the control samples annealed in a conventional forming gas ambient (H2\\/N2=4% \\/ 96%), the samples annealed in a high-pressure (10 atm) pure deuterium ambient show improved endurance and retention characteristics without the degradation of program\\/erase (P\\/E) speed. In addition, the

Sangmoo Choi; Man Jang; Hyunsang Hwang; Sanghun Jeon; Juhyung Kim; Chungwoo Kim

2004-01-01

108

An efficient bismuth tungstate visible-light-driven photocatalyst for breaking down nitric oxide.  

PubMed

This paper reports a photocatalytic removal of 400 ppb level of NO in air under visible light irradiation by utilizing three-dimensional (3D) hierarchical bismuth tungstate (Bi(2)WO(6)) microspheres. A facile microwave-assisted hydrothermal method involving bismuth nitrate and sodium wolframate was developed to synthesize the photocatalyst. The Bi(2)WO(6) samples were characterized by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Raman and ultraviolet-visible reflectance (UV-vis) spectroscopy. The relationship between the physicochemical property and the photocatalytic performance of the as prepared samples is discussed. The present work demonstrates that the 3D hierarchical Bi(2)WO(6) microspheres are effective visible-light-driven photocatalytic functional materials for air purification. PMID:20459055

Li, Guisheng; Zhang, Dieqing; Yu, Jimmy C; Leung, Michael K H

2010-06-01

109

Effect of Surface Roughness of Steels on Oxide Layer Formation in a Liquid Lead-Bismuth Flow  

SciTech Connect

Self-healed oxide layer formation on steel surfaces in liquid lead bismuth (Pb-Bi) may be effective to improve the compatibility problem for the development of the Pb-Bi cooled FBR and the ADS with a PB-Bi target. The growth, stability and property of the oxide layer may depend on the roughness of the substrate surface. The effect of convex part and dent part of the steel surfaces on the property of the oxide layer in a Pb-Bi flow was investigated for the steels which had the surface of smooth, rough and their middle roughness. The steels were exposed into a Pb- Bi flow at the temperature of 550 deg. C, the temperature difference of 150 deg. C, the flow velocity of 1 m/s and the oxygen concentration of 1.7x10{sup -8} wt% for 500 and 1,000 hours. The results showed that the initial surface roughness influenced on the oxide layer formation during the exposure. The oxide layer was cracked at the convex part of the surface. On the contrary, few cracks existed and the oxide layer remained at the dent part. That indicated thickened oxide layer caused stress due to the oxide growth, and the stress concentrated at the convex part. Few cracks appeared in a compact oxide layer which was formed on the rough surface of 9Cr steel and detached from the substrate. This was possibly caused by the stop of oxide layer growth since a metal element was not supplied from the substrate. (authors)

KONDO, Masatoshi [Tokyo Institute of Technology, Department of Nuclear Engineering 2-12-1, O-okayama, Meguro-ku, Tokyo, 152-8550 (Japan); TAKAHASHI, Minoru [Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, 2-12-1, O-okayama, Meguro-ku, Tokyo, 152-8550 (Japan); YOSHIDA, Susumu [Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, 2-12-1, O-okayama, Meguro-ku, Tokyo, 152-8550 (Japan); SAWADA, Naoki [Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, 2-12-1, O-okayama, Meguro-ku, Tokyo, 152-8550 (Japan)

2004-07-01

110

Enhancement of deposition rate of titanium silicon oxide films on silicon using hexafluorotitanic acid by nitric acid  

Microsoft Academic Search

The deposition of titanium silicon oxide films on silicon using hexafluorotitanic acid and boric acid as sources is much enhanced by nitric acid incorporation. The deposition delay time is almost zero. The structure of the films is titanium silicon oxide examined by Fourier transform infrared spectrometer. By current-voltage measurement, the leakage current of the as-deposited film with a thickness of

M. K. Lee; K. W. Tung; C. M. Yu

2005-01-01

111

Modeling of thermal oxidation of silicon: stochastic approach  

Microsoft Academic Search

It is essential that native oxide films be formed on silicon surface in manufacturing integrated circuits (ICs). Such films serve as protective masks against the diffusion of impurities, and thus, they are important components of photolithography. The formation of native oxide films is destined to proceed stochastically, especially in any nano-scale, i.e., mesoscopic, region. Herein, a stochastic model is developed

L. T. Fan; Y. Y. Chiu; A. Argoti; S. T. Chou; B. C. Shen; J. R. Schlup

2009-01-01

112

Ion beam fluorination of polysilicon coated thermal oxide on silicon  

Microsoft Academic Search

In a search for evidence of chemical interaction between fluorine and MOS interface states, F+ ions (160 keV) were implanted into polysilicon coated thermal oxides on (100) silicon wafers to a dose of 2 1015 cm-2. Chemically inert control implants were provided by the introduction into the oxide of 60 keV He+ to the same dose. The polysilicon and

J. Belson; I. H. Wilson

1984-01-01

113

Nitrogen implantation for local oxidation (NILO) of silicon  

Microsoft Academic Search

Complete physical and electrical characterisation of nitrogen implantation for local oxidation (NILO) of silicon technology is detailed. Nitrogen implantation is performed at 20 keV through 25 nm of thermal oxide with doses within the range of 5 1016-1.5 1017 cm-2. Physical characterisation of the sealed nitride films is performed using secondary ion mass spectroscopy, transmission electron microscopy, nuclear

P. Molle; C. Jaussaud; M. Bruel

1991-01-01

114

A review of oxide, silicon nitride, and silicon carbide brazing  

SciTech Connect

There is growing interest in using ceramics for structural applications, many of which require the fabrication of components with complicated shapes. Normal ceramic processing methods restrict the shapes into which these materials can be produced, but ceramic joining technology can be used to overcome many of these limitations, and also offers the possibility for improving the reliability of ceramic components. One method of joining ceramics is by brazing. The metallic alloys used for bonding must wet and adhere to the ceramic surfaces without excessive reaction. Alumina, partially stabilized zirconia, and silicon nitride have high ionic character to their chemical bonds and are difficult to wet. Alloys for brazing these materials must be formulated to overcome this problem. Silicon carbide, which has some metallic characteristics, reacts excessively with many alloys, and forms joints of low mechanical strength. The brazing characteristics of these three types of ceramics, and residual stresses in ceramic-to-metal joints are briefly discussed.

Santella, M.L.; Moorhead, A.J.

1987-01-01

115

Thermal oxidation-induced strain in silicon nanobeams  

NASA Astrophysics Data System (ADS)

The injection of self-interstitial atoms into bulk silicon during thermal oxidation has long been associated with atomic scale phenomena, such as oxidation-enhanced diffusion (OED) and the growth of oxidation-induced stacking faults (OISF). The current work suggests that interstitial injection may also be implicated in a nanoscale mechanical phenomenon. Previous researchers have found that the use sacrificial oxidation to fabricate suspended silicon nanowires results in an unexplained accumulation of permanent strain, which is manifested as buckling of the wires. We make use of suspended single-crystal silicon beams of sub-micron thickness to quantify this oxidation-induced strain (OIS) and its dependence on oxidation conditions. Dry oxidation followed by removal of the oxide via etching in HF reduces the thickness of the nanobeams, which are fixed at both ends. As a result of the oxidation, the nanobeams undergo an increase in length, which is quantified by measuring the profiles of the buckled beams. The microscale lateral dimensions of these beams facilitate their measurement by optical interferometry, allowing us to take advantage of the innate amplification of displacement that accompanies buckling. This allows us to measure very small strains, in the range of microstrain. A model for the oxidation-induced strain is developed based on the volumetric strain due to injection of Si atoms, and transition state theory is employed to express strain rate in terms of thermally activated processes. The influence of stress on these processes is also explored.

Pyzyna, Adam Michael

116

Compact and low-latency instantaneous frequency measurement using 38 cm bismuth-oxide fiber and fiber Bragg gratings.  

PubMed

We demonstrated a compact and low-latency photonic approach for broadband RF signal frequency measurement. The photonic approach does not require high-speed electronics for gigahertz RF signal measurement. Frequency-to-intensity mapping is achieved based on a two-tap finite-impulse-response filter architecture, where the time delay between signals is provided by fiber Bragg grating array. With four-wave mixing (FWM) as an optical broadband mixer, sinusoid frequency response is transferred to a DC output, where FWM is achieved in a 38 cm bismuth-oxide fiber. Thus, the resultant signal does not consist of any high-frequency component and no high-speed oscilloscope is needed for the measurement. PMID:23938415

Fok, Mable P

2013-08-10

117

Silicon oxide nanowires: facile and controlled large area fabrication of vertically oriented silicon oxide nanowires for photoluminescence and sensor applications.  

PubMed

We describe a technique for the fabrication of dense and patterned arrays of aligned silicon oxide nanowires for applications in surface modification, optoelectronic, and electromechanical based devices. Conventional techniques for the fabrication of silicon oxide nanowires based on the vapor-liquid-solid (VLS) chemical vapor deposition (CVD) processes involve the use of high temperatures and catalysts. We demonstrate a technique that extends the use of a plasma thermal reactive ion etching for the fabrication of aligned silicon oxide nanowires with aspect ratios extending up to 20 and lengths exceeding 1 ?m. The process incorporates phase separated PS-b-P4VP block copolymer loaded with an iron salt. The iron salt preferentially segregates into the P4VP layer and during an O2 etch is not removed but forms a hexagonally packed array on the silicon oxide substrate. Further etching with CHF3/O2 gas mixture over time can generate nanodots, to nanopillars, and then nanowires of silicon oxide. The photoluminescence property of the as-fabricated nanowire arrays as well as the parasitic ferromagnetic effect from the iron oxide-tipped section of the wires resulting in coalescence under an scanning electron microscope (SEM) are demonstrated. This technique is simpler compared to existing VLS fabrication approaches and can be used for the direct fabrication of patterned arrays of nanowires when a laser interference ablation step is incorporated into the fabrication procedure. PMID:23915216

Alabi, Taiwo R; Yuan, Dajun; Bucknall, David; Das, Suman

2013-09-03

118

First stages of silicon oxidation with the activation relaxation technique  

NASA Astrophysics Data System (ADS)

Using the art nouveau method, we study the initial stages of silicon oxide formation. After validating the method's parameters with the characterization of point defects diffusion mechanisms in pure Stillinger-Weber silicon, which allows us to recover some known results and to detail vacancy and self-interstitial diffusion paths, the method is applied onto a system composed of an oxygen layer deposited on a silicon substrate. We observe the oxygen atoms as they move rapidly into the substrate. From these art nouveau simulations, we extract the energy barriers of elementary mechanisms involving oxygen atoms and leading to the formation of an amorphouslike silicon oxide. We show that the kinetics of formation can be understood in terms of the energy barriers between various coordination environments.

Ganster, Patrick; Bland, Laurent Karim; Mousseau, Normand

2012-08-01

119

Numerical Modeling of Lead Oxidation in Controlled Lead Bismuth Eutectic Systems: Chemical Kinetics and Hydrodynamic Effects  

SciTech Connect

Using liquid Lead-Bismuth Eutectic (LBE) as coolant in nuclear systems has been studied for more than 50 years. And LBE has many unique nuclear, thermo physical and chemical attributes which are attractive for practical application. But, corrosion is one of the greatest concerns in using liquid Lead-Bismuth Eutectic (LBE) as spallation target in the Accelerator-driven Transmutation of Waste (ATW) program. Los Alamos National Laboratory has designed and built the Liquid Lead-Bismuth Materials Test Loop (MTL) to study the materials behavior in a flow of molten LBE. A difference of 100 deg. C was designed between the coldest and the hottest parts at a nominal flow rate of 8.84 GPM. Liquid LBE flow was activated by a mechanical sump pump or by natural convection. In order to maintain a self-healing protective film on the surface of the stainless steel pipe, a certain concentration of oxygen has to be maintained in the liquid metal. Therefore, it is of importance to understand what the oxygen concentrations are in the LBE loop related to the corrosion effects on the metal surface, the temperature profiles, the flow rates, and diffusion rates through the metal surface. The chemical kinetics also needs to be fully understood in the corrosion processes coupled with the hydrodynamics. The numerical simulation will be developed and used to analyze the system corrosion effects with different kind of oxygen concentrations, flow rates, chemical kinetics, and geometries. The hydrodynamics modeling of using computational fluid dynamics will provide the necessary the levels of oxygen and corrosion products close to the boundary or surface. This paper presents an approach towards the above explained tasks by analyzing the reactions between the Lead and oxygen at a couple of sections in the MTL. Attempt is also made to understand the surface chemistry by choosing an example model and estimating the near wall surface concentration values for propane and oxygen. (authors)

Wu, Chao; Kanthi Kiran Dasika; Chen, Yitung; Moujaes, Samir [Department of Mechanical Engineering, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas NV, 89154-4027 (United States)

2002-07-01

120

Cycling endurance of silicon-oxide-nitride-oxide-silicon nonvolatile memory stacks prepared with nitrided SiO2/Si(100) interfaces  

NASA Astrophysics Data System (ADS)

The effects of nitrided SiO2/Si(100) interfaces upon cycling endurance in silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory transistors are investigated. Analysis of metal-oxide-silicon field-effect transistor subthreshold characteristics indicate cycling degradation to be a manifestation of interface trap generation at the tunnel oxide/silicon interface. After 106 write/erase cycles, SONOS film stacks prepared with nitrided tunnel oxides exhibit enhanced cycling endurance over stacks prepared with non-nitrided tunnel oxides. If the capping oxide is formed by steam oxidation, rather than by deposition, SONOS stacks prepared with non-nitrided tunnel oxides exhibit endurance characteristics similar to stacks with nitrided tunnel oxides. For this case, a mechanism for latent nitridation of the tunnel oxide/silicon interface is proposed.

Habermehl, S.; Nasby, R. D.; Rightley, M. J.

1999-08-01

121

Zinc oxide thin-film random lasers on silicon substrate  

Microsoft Academic Search

Room-temperature ultraviolet lasing is demonstrated in mirrorless zinc oxide thin-film waveguides on (100) silicon substrate. Laser cavities, due to closed-loop optical scattering from the lateral facets of the irregular zinc oxide grains, are generated through the post-growth annealing of high-crystal-quality zinc oxide thin films obtained from the filtered cathodic vacuum arc technique. It is found that the lasing wavelength and

S. F. Yu; Clement Yuen; S. P. Lau; H. W. Lee

2004-01-01

122

Oxidation of silicon surface with atomic oxygen radical anions  

Microsoft Academic Search

The surface oxidation of silicon (Si) wafers by atomic oxygen radical anions (O- anions) and the preparation of metal-oxide-semiconductor (MOS) capacitors on the O- -oxidized Si substrates have been examined for the first time. The O- anions are generated from a recently developed O- storage-emission material of [Ca24Al28O64]4+.4O-(C12A7-O- for short). After it has been irradiated by an O- anion beam

Lian Wang; Chong-Fu Song; Jian-Qiu Sun; Ying Hou; Xiao-Guang Li; Quan-Xin Li

2008-01-01

123

Oxidation kinetics of low-oxygen silicon carbide fiber  

Microsoft Academic Search

The effect of partial pressure and temperature on the oxidation rate of low-oxygen silicon carbide fiber (Hi-Nicalon) has been investigated. The initial oxidation rate was described by a two-dimensional disc contracting formula for reaction control, and the activation energy was 155 kJ\\/mol. The rate at the later stage of oxidation obeyed the equation for diffusion control, and the activation energy

T. Shimoo; F. Toyoda; K. Okamura

2000-01-01

124

ALTERNATIVE OXIDANTS FOR SILICON FUEL IN TIME-DELAY COMPOSITIONS  

Microsoft Academic Search

Antimony trioxide, lead chromate, and copper antimonite are suitable oxidants for silicon metal in time-delay compositions ignitable by shock tubing. Measured burn rates for these systems vary from 6 to 30?mm\\/s. Lead chromate mixtures burned fastest under comparable conditions. The latter two systems show a bimodal burn rate versus silicon content dependence with a local minimum in burn rate at

I. M. M. RICCO; W. W. FOCKE; C. CONRADIE

2004-01-01

125

Dopant segregation at silicon-oxide interfaces  

NASA Astrophysics Data System (ADS)

With the fast scaling of MOSFET devices, interfaces between silicon and dielectric layers are becoming increasingly important. However, a physical understanding of dopant segregation at such interfaces using atomic resolution remains elusive in spite of intensive study. In this thesis, As and Sb are selected as dopants to achieve different levels of segregation in equilibrium conditions. This study utilizes a combination of theoretical and experimental concepts. Experimentally, three different methods (SIMS, GI-XRF and high resolution Z-contrast imaging/EELS) are used. Due to the fact that each method has its own artifacts, we use a combination of all of them to allow accurate determination of position and concentration of dopants. Additionally, ab initio calculations provide appropriate structure model by calculating the energy of different preferred segregation sites. After implanting As (1015 and 1016 cm -2) into Czochralski Si (100) wafer at 32keV, a SiO2 layer is thermally grown. Then Si/SiO2 samples are annealed at 900C for 360min in N2, with a final SiO2 thin film less than 15nm measured by ellipsometry. Combining the above three experimental methods, the segregation of As to the Si/SiO2 interface is observed. The As concentration profiles of both samples are analyzed close to the interface region by EELS, and compared with those measured by GI-XRF and SIMS. A maximum of 45x1021 cm-3 arsenic (10 16 cm-2) and 1.2x1021 cm -3 arsenic (1015 cm-2) are observed at the last monolayer of Si. The total dose loss at the interface of the 10 16 cm-2 As doped sample is 89%. With the incorporation of ab initio calculations, a physical explanation of the segregation mechanism is given based on both theoretical and experimental results. Due to the overlap of Sb, Si and O edges, neither EELS nor GI-XRF can be applied to Sb-concentration profiling in Sb (3x1015 cm-2) doped Si/SiO2 samples, which are annealed at 950C for 360min, 1000C for 20 or 60 min separately. However, Z-contrast imaging shows a segregation of Sb to the interface. Unlike the As doped samples, pentagon-shaped Sb precipitates are also detected 8nm from interface on the Si side. For the As doped Si/HfxSi1-xO samples, an unexpected silicate interfacial layer is observed between hafnium oxide thin film and silicon substrate. Therefore, As segregation at the novel interface turns out to be exactly same as As at Si/SiO2 interfaces. Combining Z-contrast imaging and EELS analysis, the interfacial layer is determined to be introduced by the kinetic problem in the MOCVD deposition of HfxSi1-x O thin film.

Pei, Lirong

126

High quality hydrogenated amorphous silicon oxide film and its application in thin film silicon solar cells  

Microsoft Academic Search

Wide gap, high quality hydrogenated intrinsic amorphous silicon oxide (i-a-SiO:H) films have been prepared by very high frequency plasma-enhanced chemical vapor deposition (60MHz VHF-PECVD) technique for using as an absorber layer for the single junction amorphous silicon solar cells. In this study, we mainly investigated the effect of plasma power density on the defect density of the films, since the

Jaran Sritharathikhun; Apichan Moollakorn; Songkiate Kittisontirak; Amornrat Limmanee; Kobsak Sriprapha

2011-01-01

127

Paramagnetic Centers in Hafnium Oxide Films on Silicon  

NASA Astrophysics Data System (ADS)

We have investigated paramagnetic defects in hafnium oxide films prepared under a fairly wide variety of processing parameters; most films were deposited with atomic layer deposition. Deposition took place on both hydrogen terminated silicon and on silicon substrates upon which a thin chemical oxide had previously been grown. In all samples, we observe Si/dielectric interface defects similar to the Si/SiO2 interface Pb centers. However, we note differences between the g tensors of defects observed in hydrogen terminated silicon substrate samples and those observed on the thin chemical oxide/silicon substrate samples. In hydrogen terminated substrate samples we consistently observe shifts in the g perpendicular component of the g tensor toward high values than those found in Si/SiO2 structures. This is not necessarily the case in hafnium oxides films deposited upon very thin SiO2 films on silicon. We also observe several paramagnetic centers in the dielectric themselves. As previously reported, we have observed a likely O2^- center. In addition, in some samples we observe a narrow ESR spectra with zero crossing g values very close to that of the free-electron g = 2.001 to 2.003. The density of these paramagnetic defects are strongly processing dependent. We speculate that these centers are within the dielectric, but very near the silicon substrate, and likely involve an unpaired electron on a silicon atom in the oxide. Work at Penn State was supported by the Semiconductor Research Corporation through Intel Corporation Funding.

Ryan, Jason; Conley, John; Tsai, Wilman

2005-03-01

128

Resonantly excited photoluminescence from porous silicon: Effects of surface oxidation on resonant luminescence spectra  

Microsoft Academic Search

We have studied the photoluminescence mechanism of freshly prepared and naturally oxidized porous silicon by fluorescence-line-narrowing spectroscopy. The surfaces of fresh and oxidized porous silicon are terminated by silicon hydrides and silicon dioxide, respectively. The TO-phonon-related structure in resonantly excited luminescence is clearly observed in H-terminated porous silicon. After surface oxidation, the luminescence intensity increases and a structure in the

Yoshihiko Kanemitsu; Shinji Okamoto

1997-01-01

129

Giant Raman gain in annealed silicon-rich silicon oxide films: Measurements at 785 nm  

NASA Astrophysics Data System (ADS)

Stimulated Raman scattering in silicon-rich silicon oxide (SiOx, x < 2) films annealed at 1200 C is measured with excitation at 785 nm. Our main objective is to confirm giant Raman gain, recently reported in annealed SiOx films for excitation at ~1500 nm. Another important aspect is the possibility of using SiOx films for the realization of a Raman laser in the visible region. The measurements were performed in the backscattering geometry in a Raman microscope. As a result, the observed Raman gain is orders of magnitude greater than in crystalline silicon.

Nikitin, Timur; Novikov, Sergei; Khriachtchev, Leonid

2013-10-01

130

Surface chemistry dependence of native oxidation formation on silicon nanocrystals  

SciTech Connect

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.

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

131

Surface chemistry dependence of native oxidation formation on silicon nanocrystals  

NASA Astrophysics Data System (ADS)

The growth of silicon oxide on bare and SF6-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 SF6 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.

Liptak, R. W.; Kortshagen, U.; Campbell, S. A.

2009-09-01

132

Correlation between transport, dielectric, and optical properties of oxidized and nonoxidized porous silicon  

Microsoft Academic Search

Using the correlation between transport, dielectric relaxation phenomena, and the state of oxidation of porous silicon, we have found that there are two major transport routes in the porous silicon medium. The first route of conduction via the disordered tissue that surrounds the silicon nanocrystals dominates for nonoxidized porous silicon and gradually disappears during the first stage of oxidation, where

B. Urbach; E. Axelrod; A. Sa'Ar

2007-01-01

133

The influence of bottom oxide thickness on the extraction ofthetrap energy distribution in SONOS (silicon-oxide-nitride-oxide-silicon) structures  

Microsoft Academic Search

The charge retention characteristics of SONOS (silicon-oxide-nitride-oxide-silicon) non-volatile memory cells at elevated\\u000a temperatures were investigated. Assuming thermal excitation to be the dominant charge loss mechanism, the trap energy distribution\\u000a in the nitride was determined. We present an improved model which includes the influence of subsequent tunneling of the charge\\u000a carriers through the bottom oxide after being thermally emitted into the

K. Bernert; C. Oestreich; J. Bollmann; T. Mikolajick

2010-01-01

134

Zinc oxide varistors and/or resistors  

DOEpatents

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.

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

1993-01-01

135

In-situ Neutron Diffraction Studies of the Reduction of a Model of an Oxidations Catalyst (ferric molybdate and bismuth molybdate)  

NASA Astrophysics Data System (ADS)

Three elements commonly found in metal oxide alkene oxidation catalysts are molybdenum, bismuth and iron. In the case of ammoxidation of propylene to acrylonitrile many catalyst have ferric molybdate and a mixture of bismuth molybdates present in the as-prepared formulations. It is generally recognized that during catalyst activation ferric molybdate is reduced to Fe^+2 phases, freeing molybdenum oxide for the formation of other phases. It is suspected, but has never been demonstrated, that this excess MoO3 then reacts with the bismuth containing phase(s) to form the active catalyst phase. Although this reaction is generally believed to occur in a number of catalytic processes the mechanism of the reaction has never been extensively studied. Due to the ease of in-situ measurements and the sensitivity to oxygen in the presence of heavy metals neutron diffraction is an ideal probe to study this reaction mechanism. We have developed a reaction cell that can be used in the General Purpose Powder Diffractometer at IPNS, ANL for time resolved in situ study. Recent upgrades to GPPD, which have increased data rates by a factor of 6, now make these measurements possible. Preliminary findings about the evolution of a model oxidation catalyst under reaction conditions will be presented in this talk.

Huq, Ashfia

2005-03-01

136

Nonlinear optical properties of low temperature annealed silicon-rich oxide and silicon-rich nitride materials for silicon photonics  

SciTech Connect

We investigate the nonlinear optical properties of Si-rich silicon oxide (SRO) and Si-rich silicon nitride (SRN) samples as a function of silicon content, annealing temperature, and excitation wavelength. Using the Z-scan technique, we measure the non-linear refractive index n{sub 2} and the nonlinear absorption coefficient {beta} for a large number of samples fabricated by reactive co-sputtering. Moreover, we characterize the nonlinear optical parameters of SRN in the broad spectral region 1100-1500 nm and show the strongest nonlinearity at 1500 nm. These results demonstrate the potential of the SRN matrix for the engineering of compact devices with enhanced Kerr nonlinearities for silicon photonics applications.

Minissale, S. [Photonics Center, Boston University, 8 Saint Mary's street, Boston, Massachusetts 02215-2421 (United States) and Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States); Yerci, S. [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States); Dal Negro, L. [Photonics Center, Boston University, 8 Saint Mary's street, Boston, Massachusetts 02215-2421 (United States) and Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States); Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States)

2012-01-09

137

Laser Induced Oxidation of Heavily Doped Silicon.  

National Technical Information Service (NTIS)

We have investigated the incorporation of oxygen into heavily doped silicon during uv excimer laser irradiation. For the case of repetitive laser irradiations in air, the amount of oxygen incorporated into Si depends markedly on the dopant. For As and Sb ...

E. Fogarassy C. W. White D. H. Lowndes J. Narayan

1985-01-01

138

Effect of Bismuth Oxide Radioopacifier Content on the Material Properties of an Endodontic Portland Cementbased (MTA-like) System  

Microsoft Academic Search

The effect of bismuth oxide (Bi2O3) radioopacifier addition on the material properties of an endodontic Portland cementbased system were investigated. Increasing Bi2O3 content from 0 to 10 wt % resulted in a deterioration of mechanical strength from 82 to 40 MPa, decreasing gradually on further addition to 29 MPa for 40 wt %. Bi2O3 content increase also gradually increased the

Kristian S. Coomaraswamy; Philip J. Lumley; Michael P. Hofmann

2007-01-01

139

Effect of Light Irradiation on Native Oxidation of Silicon Surface  

Microsoft Academic Search

We found that shielding wafers from visible light is effective to prevent native oxidation of silicon. Hydrogen terminated p-Si(100) (8-12 Omega{\\\\cdot}cm) wafers were stored in wafer boxes under various brightness levels. The oxidation rate in a dark box (0 lx) is less than 0.01 nm\\/12 h, while that in a light box (1000 lx) is approximately 0.1 nm\\/12 h.

Takenobu Yoshino; Shin Yokoyama; Toshiaki Fujii

2001-01-01

140

Sputtered tin silicon oxide films for durable solar control coatings  

Microsoft Academic Search

The optical, mechanical, and chemical properties of solar control coatings with a transparent tin silicon oxide (TSO) film were investigated. The TSO films were formed by reactive dc sputtering from alloy targets with the compositions of 90Sn10Si, 80Sn20Si, and 50Sn50Si (at.%). Hereafter, the 50TSO film denotes the oxide film prepared from the 50Sn-50Si target. Triple layer (50TSO\\/TiNx\\/50TSO\\/glass) and double layer

E. Ando; S. Suzuki; J. Shimizu; Y. Hayashi

1999-01-01

141

Oxygen diffusion in silicon oxide films produced by different methods  

Microsoft Academic Search

Thin films of silicon oxide were prepared on copper substrates using several techniques, such as DC sputtering, sol-gel and microwave decomposition of gases (SiH4 and O2). The sol-gel films were made using a conventional mixture of tetraethoxysilane (TEOS), water and ethanol, with various TEOS\\/water ratios. The oxygen diffusion coefficient is found from the thickness of the copper oxide layer formed

J. J Prez-Bueno; R Ram??rez-Bon; Y. V Vorobiev; F. Espinozabeltran; J. Gonzalezhernandez

2000-01-01

142

Correlation of gate oxide integrity with crystalline defects in silicon  

Microsoft Academic Search

This thesis is concerned with gate oxide integrity degradation due to crystal silicon grown-in and process-induced defects. Many tools have been invented to detect these defects, however, clear explanations for the gate oxide integrity degradation mechanism of these defects are still missing. One of the major difficulties of studying grown-in micro defects is their low density, below 10sp6\\\\ cmsp{-3}. Therefore,

Masaro Tamatsuka

1997-01-01

143

MOS Properties of Ultra Thin Oxides on Silicon  

Microsoft Academic Search

With some newly developed procedures it has become possible to grow ultra thin oxides on silicon in a series of steps operated at low temperature to achieve a good control of the interface properties. The growth mode is linear between 0.3nm and 10nm with a precision of one 3atomic layer (0.25nm) pr. step. This includes the thinnest possible oxide-like layer

Per Morgen; Thomas Jensen; Carsten Gundlach; Lars-Bo Tkker; Sren V. Hoffman; Zheshen S. Li; Kjeld Pedersen

2002-01-01

144

Model for the Oxidation of Carbon Silicon Carbide Composite Structures.  

National Technical Information Service (NTIS)

A mathematical theory and an accompanying numerical scheme have been developed for predicting the oxidation behavior of carbon silicon carbide (C/SiC) composite structures. The theory is derived from the mechanics of the flow of ideal gases through a poro...

R. M. Sullivan

2004-01-01

145

Properties of Silicon and Metal Oxide Electrowetting Systems  

Microsoft Academic Search

This paper is a review of our recent work on electrowetting properties of devices based on silicon (Si) and metal oxide (MO) electrodes. In particular, the electrowetting-on-dielectric (EWOD) properties of three- dimensional (3D) structured Si and MO electrodes are investigated and compared with those of planar ones. It is shown that the EWOD properties of these materials can be advantageously

Evie L. Papadopoulou; Vassilia Zorba; Emmanuel Stratakis; Costas Fotakis

2012-01-01

146

Sputter deposition of siliconoxide coatings  

Microsoft Academic Search

Fused silica and SiOx coatings are of interest for use under high flux conditions of laser light. SiOx coatings are sputter deposited from silicon and fused quartz targets using planar magnetrons operated in the r.f. mode with a variable working-gas mixture of ArgonOxygen. A series of coatings are prepared on optically flat, fused quartz substrates. Analysis of surface curvature reveals

A. F Jankowski; J. P Hayes; T. E Felter; C Evans; A. J Nelson

2002-01-01

147

Sub-50nm positioning of organic compounds onto silicon oxide patterns fabricated by local oxidation nanolithography.  

PubMed

We present a process to fabricate molecule-based nanostructures by merging a bottom-up interaction and a top-down nanolithography. Direct nanoscale positioning arises from the attractive electrostatic interactions between the molecules and silicon dioxide nanopatterns. Local oxidation nanolithography is used to fabricate silicon oxide domains with variable gap separations ranging from 40nm to several microns in length. We demonstrate that an ionic tetrathiafulvalene (TTF) semiconductor can be directed from a macroscopic liquid solution (1M) and selectively deposited onto predefined nanoscale regions of a 1cm(2) silicon chip withan accuracy of 40nm. PMID:21832773

Losilla, N S; Oxtoby, N S; Martinez, J; Garcia, F; Garcia, R; Mas-Torrent, M; Veciana, J; Rovira, C

2008-10-08

148

Origin of complex impact craters on native oxide coated silicon surfaces  

NASA Astrophysics Data System (ADS)

Crater structures induced by impact of keV-energy Arn+ cluster ions on silicon surfaces are measured with atomic force microscopy. Complex crater structures consisting of a central hillock and outer rim are observed more often on targets covered with a native silicon oxide layer than on targets without the oxide layer. To explain the formation of these complex crater structures, classical molecular dynamics simulations of Ar cluster impacts on oxide coated silicon surfaces, as well as on bulk amorphous silica, amorphous Si, and crystalline Si substrates, are carried out. The diameter of the simulated hillock structures in the silicon oxide layer is in agreement with the experimental results, but the simulations cannot directly explain the height of hillocks and the outer rim structures when the oxide coated silicon substrate is free of defects. However, in simulations of 5keV /atom Ar12 cluster impacts, transient displacements of the amorphous silicon or silicon oxide substrate surfaces are induced in an approximately 50nm wide area surrounding the impact point. In silicon oxide, the transient displacements induce small topographical changes on the surface in the vicinity of the central hillock. The comparison of cluster stopping mechanisms in the various silicon oxide and silicon structures shows that the largest lateral momentum is induced in the silicon oxide layer during the impact; thus, the transient displacements on the surface are stronger than in the other substrates. This can be a reason for the higher frequency of occurrence of the complex craters on oxide coated silicon.

Samela, Juha; Nordlund, Kai; Popok, Vladimir N.; Campbell, Eleanor E. B.

2008-02-01

149

Silicon nanowire circuits fabricated by AFM oxidation nanolithography.  

PubMed

We report a top-down process for the fabrication of single-crystalline silicon nanowire circuits and devices. Local oxidation nanolithography is applied to define very narrow oxide masks on top of a silicon-on-insulator substrate. In a plasma etching, the nano-oxide mask generates a nanowire with a rectangular section. The nanowire width coincides with the lateral size of the mask. In this way, uniform and well-defined transistors with channel widths in the 10-20 nm range have been fabricated. The nanowires can be positioned with sub-100 nm lateral accuracy. The transistors exhibit an on/off current ratio of 10(5). The atomic force microscope nanolithography offers full control of the nanowire's shape from straight to circular or a combination of them. It also enables the integration of several nanowires within the same circuit. The nanowire transistors have been applied to detect immunological processes. PMID:20484797

Martnez, Ramses V; Martnez, Javier; Garcia, Ricardo

2010-05-20

150

Influence of bismuth on the charging ability of negative plates in leadacid batteries  

Microsoft Academic Search

To examine the influence of bismuth on the charging ability of negative plates in leadacid batteries, plates are made from three types of oxides: (i) leady oxide of high quality which contains virtually no bismuth (termed control oxide); (ii) control oxide in which bismuth oxide is blended at bismuth levels from 0.01 to 0.12wt.%; (iii) leady oxide produced from Pasminco

L. T Lam; H Ceylan; N. P Haigh; J. E Manders

2002-01-01

151

Amorphous silicon thin-film transistor with fluorinated silicon oxide ion stopper  

Microsoft Academic Search

We propose fluorinated silicon oxide (SiOF) as the ion-stopper of bottom-gate amorphous silicon thin film transistors (a-Si:H TFTs). The low dielectric constant SiOF on both the back-channel of the TFT and the crossover regions of gate\\/data lines can contribute to reducing the RC delay of the gate pulse signal in active-matrix liquid-crystal displays. Besides, the a-Si:H TFT with a SiOF

Kyung Wook Kim; Kyu Sik Cho; Jai Il Ryu; Keon Ho Yoo; Jin Jang

2000-01-01

152

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)

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.

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

2013-06-01

153

Stable mode-locked fiber laser using 49 cm long bismuth oxide based erbium doped fiber and slow saturable absorber  

NASA Astrophysics Data System (ADS)

A stable mode-locked fiber laser employing a 49 cm long bismuth oxide based erbium doped fiber (Bi-EDF) by using a slow saturable absorber is demonstrated. Near transform limited short pulses with a repetition rate of 8.27 MHz are obtained at a wavelength of 1560 nm with a maximum spectral width of 15 nm. Results indicate that pulse characteristics are strongly dependent on pump power rather than spectral width. Moreover the Time-Bandwidth products (TBWP), pulse duration, the energy fluctuation and timing jitter decrease with increasing pump power. The pulse width is continuously varied from 1.2 ps to less than 300 fs. It produces stable mode locking with a maximum spectral width of 15 nm, minimum timing jitter of 4 ps and energy fluctuations of 2.5%. The pulse train was amplified using a two-stage amplifier up to 447 mW average power corresponding to peak powers of 177.3 kW.

Moghaddam, M. R. A.; Harun, S. W.; Akbari, R.; Ahmad, H.

2011-05-01

154

Nitrogen implantation for local oxidation (NILO) of silicon  

NASA Astrophysics Data System (ADS)

Complete physical and electrical characterisation of nitrogen implantation for local oxidation (NILO) of silicon technology is detailed. Nitrogen implantation is performed at 20 keV through 25 nm of thermal oxide with doses within the range of 5 1016-1.5 1017 cm-2. Physical characterisation of the sealed nitride films is performed using secondary ion mass spectroscopy, transmission electron microscopy, nuclear reaction analysis and X-ray photoelectron spectroscopy. Nitrogen implantation in silicon can provide sealed nitride films of thicknesses around 20-25 nm, capable of masking a 550 nm field oxidation. Physical characterisation shows that implanted nitride films are composed of elemental Si-Si4 bonds, silicon oxynitride and diffused oxygen. The nitrogen concentration in such films is lower than that of a stoichiometric nitride. ``Bird's beak'' lengths as short as 0.08 ?m can be obtained. For a 950 C field oxide temperature, dislocations are observed at the edge of the nitride mask. At a higher temperature (1050 C) no dislocations are observed; on the other hand, stacking faults with a density of 0.05 faults per ?m of mask length are observed at the edge of the nitride mask. Because of the presence of the stacking faults, high leakage currents are measured on n+ p diodes.

Molle, P.; Jaussaud, C.; Bruel, M.

1991-04-01

155

Structural and Chemical Investigations of Thin and Native Oxides on Silicon  

Microsoft Academic Search

Thin silicon dioxide layers on silicon serve critical needs in current microelectronic technology and will play a pivotal role in future advancements. The structural integrity and chemical characteristics of these oxides and their interface with single-crystal silicon substrates are therefore of great interest. In this work, high resolution transmission electron microscopy is used to directly examine thin oxide morphology at

Altaf Hyder Carim

1989-01-01

156

Nature of Ultra-thin oxides on silicon  

NASA Astrophysics Data System (ADS)

Infrared absorption and X-ray photoelectron spectroscopies are used to characterize 2-10thin silicon oxide films grown by wet chemistry (H_2O2 with H_2SO_4, HCl or HNO_3). Analysis of the SiOx TO and LO phonons in 900-1300 cm-1 range, the Si-H bends around 600 cm-1 and Si-H stretches in the 2100-2300 cm-1 range, as well as the Si_2p core level show that all these chemical oxides undergo structural and stoichiometric changes upon annealing in vacuum up to 800^oC at which point they desorb. While the stoichiometry evolved towards that of comparably thin thermal oxides, the chemical oxides exhibit upon annealing a high frequency LO mode at 1270 cm-1 that is linked to highly strained Si-O-Si bonds (linkage between tetrahedra as the oxides densify), and a a low frequency TO mode at 990 cm-1 that is associated with a monolayer of lower stoichiometry oxides on Si surfaces. In vacuum, all the oxides appear to roughen prior to desorption, although the sulfuric acid grown oxide is by far the most homogeneous and remains the most stable. Carbon and additional oxygen are incorporated into the oxide from the adsorbed hydrocarbon and hydroxyl molecules at the oxide upon annealing.

Chabal, Y. J.; Gurevich, Alejandra; Weldon, M. K.; Opila, R. L.

1998-03-01

157

Structure and lattice dynamics of heterostructures based on bismuth ferrite and barium strontium titanate on magnesium oxide substrates  

Microsoft Academic Search

Bismuth ferrite films doped with neodymium on MgO single-crystal substrates with an epitaxial barium strontium titanate thin (1-2 nm) sublayer have been prepared by rf sputtering of ceramic targets at an elevated oxygen partial pressure and at temperatures below the ferroelectric and magnetic transition temperatures. It has been revealed using X-ray diffraction and Raman scattering spectroscopy that, in these bismuth

Yu. I. Golovko; V. M. Mukhortov; O. A. Bunina; I. N. Zakharchenko; A. S. Anokhin; V. B. Shirokov; Yu. I. Yuzyuk

2010-01-01

158

Structure and lattice dynamics of heterostructures based on bismuth ferrite and barium strontium titanate on magnesium oxide substrates  

Microsoft Academic Search

Bismuth ferrite films doped with neodymium on MgO single-crystal substrates with an epitaxial barium strontium titanate thin\\u000a (12 nm) sublayer have been prepared by rf sputtering of ceramic targets at an elevated oxygen partial pressure and at temperatures\\u000a below the ferroelectric and magnetic transition temperatures. It has been revealed using X-ray diffraction and Raman scattering\\u000a spectroscopy that, in these bismuth

Yu. I. Golovko; V. M. Mukhortov; O. A. Bunina; I. N. Zakharchenko; A. S. Anokhin; V. B. Shirokov; Yu. I. Yuzyuk

2010-01-01

159

Crystalline zirconia oxide on silicon as alternative gate dielectrics  

NASA Astrophysics Data System (ADS)

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 , the leakage current is about 1.110-3 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 2.01011 eV-1 cm-2, respectively.

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

160

Interfacial Structure in Silicon Nitride Sintered with Lanthanide Oxide  

SciTech Connect

Three independent research groups present a comparison of their structural analyses of prismatic interfaces in silicon nitride densified with the aid of lanthanide oxide Ln{sub 2}O{sub 3}. All three groups obtained scanning transmission electron microscope images which clearly reveal the presence of well-defined Ln segregation sites at the interfaces, and, moreover, reveal that these segregation sites are element-specific. While some results differ across the three research groups, the vast majority exhibits good reproducibility.

Dwyer, C. [University of Oxford; Ziegler, A. [Lawrence Berkeley National Laboratory (LBNL); Shibata, Naoya [University of Tokyo, Tokyo, Japan; Winkelman, G. B. [University of Oxford; Satet, R. L. [Universituet Karlsruhe, Germany; Hoffmann, M. J. [Universituet Karlsruhe, Germany; Cinibulk, M. K. [Air Force Research Laboratory; Becher, Paul F [ORNL; Painter, Gayle S [ORNL; Browning, N. D. [University of California, Davis; Cockayne, D.J.H. [University of Oxford; Ritchie, R O [University of California, Berkeley; Pennycook, Stephen J [ORNL

2006-01-01

161

Low Dielectric Constant Interlayer Using Fluorine-Doped Silicon Oxide  

Microsoft Academic Search

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

Takashi Usami; Kimiaki Shimokawa; Masaki Yoshimaru

1994-01-01

162

Electron beam induced current analysis of metal oxide silicon structures  

Microsoft Academic Search

This thesis presents the history and the development of the scanning electron microscopy (SEM) of Metal-Oxide-Silicon structures by the Electron-Beam-Induced-Current technique (MOS\\/EBIC) through the year 1997. General experimental results are described which reveal the behavior of MOS capacitor structures under the influence of electron beam irradiation as well as the developments which led in a very natural way to a

Harry Robert Kirk

1998-01-01

163

Ceramic Bearing Development. Silicon Nitride Bearing Balls of Improved Reliability: Thermal Oxidation.  

National Technical Information Service (NTIS)

The major objective of this work was to improve the reliability of silicon nitride bearing balls by means of an optimized thermal oxidation treatment. Previous work had shown that the thermal fracture resistance of silicon nitride bearing balls increased ...

C. B. Burk

1996-01-01

164

Increases in photovoltage of ``indium tin oxide\\/silicon oxide\\/mat-textured n-silicon'' junction solar cells by silicon preoxidation and annealing processes  

Microsoft Academic Search

Indium-tin-oxide (ITO)\\/silicon oxide\\/mat-textured n-Si junction solar cells having an energy conversion efficiency of 15% are fabricated by the spray pyrolysis method. Their characteristics and the junction properties are compared with the same junction solar cells having a flat Si surface. In cases where the ITO film is deposited on a hydrofluoric acid-etched mat-textured Si surface, the open circuit photovoltage (Voc)

H. Kobayashi; Y. Kogetsu; T. Ishida; Y. Nakato

1993-01-01

165

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

SciTech Connect

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.

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

166

Luminescence of porous silicon derived nanocrystals dispersed in water: dependence on initial porous silicon oxidation  

Microsoft Academic Search

Aqueous solutions of silicon nanocrystals have been obtained, by sonication, from porous Si (p-Si) aged in air for various\\u000a times. The photoluminescence of these solutions changes with the aging time of p-Si. These changes correlate with nanocrystal\\u000a core dimensions, i.e. with the oxidation of the nanocrystals. Infrared spectra show that the reaction with water depends on\\u000a the age of the

Elena Froner; Roberta Adamo; Zeno Gaburro; Benno Margesin; Lorenzo Pavesi; Adelio Rigo; Marina Scarpa

2006-01-01

167

Surface Barrier Silicon Radiation Detectors Improved by Using a Tungsten Oxide for the Surface Stability  

Microsoft Academic Search

The improvements of surface barrier silicon radiation detectors have been accomplished by evaporating a tungsten oxide material on the surface of n-type silicon substrate as the surface stabilized film before gold electrode deposition, the structure of which is metal-metal oxide-semiconductor type. The stability and electrical characteristics of improved silicon detectors are better than those of the conventional surface barrier silicon

Y. Ishizuka; C. Kim; Y. Kim; S. Ohkawa; K. Husimi; S. Osada; M. Ishii

1986-01-01

168

Total oxidation of methane over Pd catalysts supported on silicon nitride  

Microsoft Academic Search

Non-oxide refractory materials such as silicon nitride showing high thermal stability and thermal conductivity can be used as catalytic supports. Silicon nitride with different specific area and crystallinity: amorphous silicon nitride (SiN-am), amorphous silicon nitride annealed at 1450C (120min) under nitrogen flow (SiN-annl) and ?-Si3N4 were chosen as supports for Pd catalysts. Commercial amorphous silicon nitride contains a small amount

I. Kurzina; F. J. Cadete Santos Aires; G. Bergeret; J. C. Bertolini

2005-01-01

169

Electric current generation in photorefractive bismuth silicon oxide without application of external electric field  

NASA Astrophysics Data System (ADS)

A holographic radial diffraction grating (HRDG) is an efficient optical element for splitting single laser beam on three 0, -1st, and +1st- diffraction order beams. The rotation of the grating at certain velocity allows a window for quality control over the frequency detuning between -1st, and +1st diffracted beams. The running interference fringes produced by the beams and projected on photorefractive crystal induce running holographic gratings in the crystal. This simple configuration is an effective tool for the study of such phenomena as space charge waves [1], domains motion [2], and electric current generation [3]. Specifics of photorefractive mechanism in cubic photorefractive crystals (BSO, BTO) normally require a use of external electric field to produce reasonable degree of refractive index modulation to observe associated with it phenomena. In this work we provide a direct experimental observation of the electric current generated in photorefractive BSO using running grating technique without an applied electric field. Moving interference fringes modulate a photoconductivity and an electric field in photorefractive crystal thus creating the photo electro-motive force (emf) and the current. The magnitude of the current varies between 1 and 10 nA depending on the rotation speed of HRDG. The peculiarities of the current behavior include a backward current flow, and current oscillations. The holographic current generated through this technique can find applications in non-destructive testing for ultra-sensitive vibrometry, materials characterization, and for motion sensors. References [1] S.F. Lyuksyutov, P. Buchhave, and M.V. Vasnetsov, Physical Review Letters, 79, No.1, 67-70 (1997) [2] P. Buchhave, S. Lyuksyutov, M. Vasnetsov, and C. Heyde, Journal Optical Society of America B, 13, No.11 2595-2602 (1996) [3] M. Vasnetsov, P. Buchhave, and S. Lyuksyutov Optics Communications, 137, 181-191 (1997)

Buchhave, Preben; Kukhtarev, Nickolai; Kukhtareva, Tatiana; Edwards, Matthew E.; Reagan, Michael A.; Lyuksyutov, Sergei F.

2003-10-01

170

Epitaxial growth of zinc oxide thin films on silicon (100) substrates with zirconia buffer layer  

Microsoft Academic Search

As an II-VI semiconductor, with wide bandgap and high exciton binding energy, zinc oxide has been favored for the new opto-electronic devices. One of the key issues for such applications is the integration of the zinc oxide onto silicon substrates. In this paper, we report a new integration methodology for depositing high quality zinc oxide thin films on silicon substrates.

Ravi Aggarwal; Chunming Jin; Wei Wei; Jagdish Narayan; Roger J. Narayan

2008-01-01

171

Integration of functional oxide thin film heterostructures with silicon (100) substrates  

Microsoft Academic Search

The novel functionalities of metal oxides provide the opportunity for the development of next generation optoelectronic, spintronic and a host of other multifunctional devices. A critical issue in the development of practical devices based on metal oxides is the integration of high quality epitaxial oxide thin films with the existing silicon technology which is based on silicon (100) substrates. However,

Ravi Aggarwal

2010-01-01

172

Spectromicroscopic study of plasma-treatment effect on InP-substrate-based silicon nitride and silicon oxide patterns  

Microsoft Academic Search

Oxygen-plasma treatment was applied to silicon nitride and silicon oxide patterns on an InP substrate, and the effect was investigated by using scanning photoelectron microscopy. After the plasma treatment, the relative intensity of the carbon content was noticeably reduced on the surfaces of the patterns and the substrate, which indicates that the plasma treatment effectively removed the remaining carbon and

M.-K. Lee; H.-J. Shin; J.-H. Choi; D.-S. Bang

2004-01-01

173

Single-wafer furnace RTCVD for silicon oxide, nitride, and oxynitride thin films  

Microsoft Academic Search

We have developed single-wafer RTP modules for LPCVD of silicon nitride, oxynitride, oxide, and oxide\\/nitride\\/oxide (ONO) composite films. All films were deposited from dichlorosilane (DCS) as a silicon source gas. The deposition of 20-40 silicon nitride films from DCS and NH3 showed excellent thickness uniformity. Continuous 10-wafer runs at 735C resulted in 40 Si3N4 films with within-wafer uniformity

Y. Senzaki; C. Barelli; D. Teasdale; J. Sisson; R. Herring

2001-01-01

174

Characterization of silicon nanowires grown on silicon, stainless steel and indium tin oxide substrates  

NASA Astrophysics Data System (ADS)

Silicon nanowires (SiNWs) have been grown on crystalline silicon (Si), indium tin oxide (ITO) and stainless steel (SS) substrates using a gold catalyst coating with a thickness of 200 nm via pulsed plasma-enhanced chemical vapor deposition (PPECVD). Their morphological, mineralogical and surface characteristics have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman analysis. SiNWs growth is accompanied by oxidation, thus yielding partially (SiO x ) and fully oxidized (SiO2) Si sheaths. The mean diameters of these SiNWs range from 140 to 185 nm. Si with (111) and (220) planes exists in SiNWs grown on all three substrates while Si with a (311) plane is detected only for Si and ITO substrates. Computational simulation using density functional theory (DFT) has also been conducted to supplement the experimental Raman analyses for crystalline Si and SiO2. XPS results reveal that ca. 30 % of the SiNWs have been oxidized for all substrates. The results presented in this paper can be used to aid selection of appropriate substrates for SiNW growth, depending on specific applications.

Jennings, Philip; Jiang, Zhong-Tao; Wyatt, Nicholas M. W.; Parlevliet, David; Creagh, Christine; Yin, Chun-Yang; Widjaja, Hantarto; Mondinos, Nick

2013-02-01

175

Oxide and interface characteristics of oxidized silicon oxynitride ceramics an investigation by electron microscopy  

Microsoft Academic Search

Hot-isostatically pressed silicon oxynitride (Si2N2O) ceramics free from sintering aids were oxidized in 1 atm dry oxygen at 1100 and 1300C. The structural and chemical characteristics of the oxide and the nature of the oxideSi2N2O interface were determined using cross-sectional transmission electron microscopy in conjunction with small-probe energy dispersive X-ray analysis and selected-area electron diffraction. Oxidation of Si2N2O resulted in

D. Manessis; Honghua Du; R. Larker

1998-01-01

176

Textured crystallization of ultrathin hafnium oxide films on silicon substrate  

NASA Astrophysics Data System (ADS)

The effects of rapid thermal annealing are reported here on the structure of 2 nm thick hafnium oxide films grown on silicon (100) substrates. The films grown by atomic layer deposition have a 1 nm SiO2 transition layer between silicon and the HfO2 layer. The amorphous structure of the as-deposited films is retained after annealing at 600 C. The HfO2 films crystallized into an orthorhombic phase with an out-of-plane texture after annealing at 800 C or higher. In contrast, films grown on thick amorphous SiO2 substrates crystallize without any texture. The authors attribute the texture of HfO2 on Si (100) to the role of interfacial SiO2 transition layer.

Bohra, Fakhruddin; Jiang, Bin; Zuo, Jian-Min

2007-04-01

177

Ab initio study on oxidized silicon clusters and silicon nanocrystals embedded in Si O2 : Beyond the quantum confinement effect  

Microsoft Academic Search

Density-functional theory calculations have been carried out in order to study the structural, electronic, and optical properties of oxidized silicon clusters and silicon nanocrystals embedded in SiO2 . For the isolated clusters, different Si\\/O bonding geometries and various levels of oxidation have been investigated, checking also the dependence of the results on the structure size. We provide strong evidences that

Marcello Luppi; Stefano Ossicini

2005-01-01

178

Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation  

Microsoft Academic Search

A leading approach for large-scale electrochemical energy production with minimal global-warming gas emission is to use a renewable source of electricity, such as solar energy, to oxidize water, providing the abundant source of electrons needed in fuel synthesis. We report corrosion-resistant, nanocomposite anodes for the oxidation of water required to produce renewable fuels. Silicon, an earth-abundant element and an efficient

Yi Wei Chen; Jonathan D. Prange; Simon Dhnen; Yohan Park; Marika Gunji; Christopher E. D. Chidsey; Paul C. McIntyre

2011-01-01

179

The Bismuth Telluride-Bismuth Selenide System.  

National Technical Information Service (NTIS)

These data sheets present a compilation of a wide range of electronic properties for the bismuth telluride-bismuth selenide system. Electrical properties include conductivity, dielectric constant, Hall coefficient, and mobility. Emission data were broken ...

M. Neuberger

1966-01-01

180

STM-induced surface aggregates on metals and oxidized silicon  

NASA Astrophysics Data System (ADS)

We have observed an aggregation of carbon or carbon derivatives on platinum and natively oxidized silicon surfaces during STM measurements in ultra-high vacuum on solvent-cleaned samples previously structured by e-beam lithography. We imaged the aggregated layer with scanning tunneling microscopy (STM) as well as scanning electron microscopy (SEM). The amount of the aggregated material increases with the number of STM scans and with the tunneling voltage. Film thicknesses of up to 10 nm with five successive STM measurements of the same area have been obtained.

Stffler, Dominik; Lhneysen, Hilbert V.; Hoffmann, Regina

2011-08-01

181

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

SciTech Connect

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.

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

182

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

183

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

SciTech Connect

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.

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

184

Silicon oxide based n-doped layer for improved performance of thin film silicon solar cells  

NASA Astrophysics Data System (ADS)

We propose the use of n-doped silicon oxide as alternative n-layer in thin film Si p-i-n solar cells. By varying input gas ratios, films with a wide range of optical and electrical properties are obtained. Applying these layers in solar cells, good electrical and optical properties are demonstrated. A relative efficiency increase up to 13.6% has been observed on the cells adopting a simple Ag back contact. A similar spectral response as with the cell with standard n-layer plus ZnO/Ag back contact is obtained. The deposition of a buffer layer at the back contact can therefore be avoided.

Delli Veneri, Paola; Mercaldo, Lucia V.; Usatii, Iurie

2010-07-01

185

Analysis of bi-layer oxide on austenitic stainless steel, 316L, exposed to Lead-Bismuth Eutectic (LBE) by X-ray Photoelectron Spectroscopy (XPS)  

NASA Astrophysics Data System (ADS)

Corrosion of the austenitic stainless steel alloy 316L by Lead-Bismuth Eutectic (LBE) was studied using X-ray Photoelectron Spectroscopy (XPS) with Sputter-Depth Profiling (SDP), and compared to data taken by Scanning Electron Microscopy (SEM) and Energy Dispersive X-rays (EDXs). Exposed and unexposed samples were compared. Annealed 316L samples, exposed to LBE for durations of 1000, 2000 and 3000 h, developed bi-layer oxides up to 30 ?m thick. Analysis of the charge-states of the 2p3/2 peaks of iron, chromium, and nickel in the oxide layers reveal an inner layer consisting of iron and chromium oxides (likely spinel-structured) and an outer layer consisting of iron oxides (Fe3O4). Cold-rolled 316L samples, exposed for the same durations, form a chromium-rich, thin (?1 ?m) oxide with some oxidized iron in the outermost 200 nm of the oxide layer. This is the first experiment to investigate what components of the 316L are oxidized by LBE exposure. It is shown here that nickel is metallic in the inner layer.

Koury, D.; Johnson, A. L.; Ho, T.; Farley, J. W.

2013-09-01

186

Correlation of gate oxide integrity with crystalline defects in silicon  

NASA Astrophysics Data System (ADS)

This thesis is concerned with gate oxide integrity degradation due to crystal silicon grown-in and process-induced defects. Many tools have been invented to detect these defects, however, clear explanations for the gate oxide integrity degradation mechanism of these defects are still missing. One of the major difficulties of studying grown-in micro defects is their low density, below 10sp6\\ cmsp{-3}. Therefore, precise defect localization techniques are needed. To solve this problem, we focused on the metal oxide semiconductor (MOS)/electron beam induced current (EBIC) technique which is the only method to achieve a direct one-to-one correlation of defects and degradation source. Finally, we have developed a novel failure analysis procedure using scanning electron microscopy (SEM)/EBIC image identification of individual breakdown sites under sub-nano ampere stress currents, followed by focused ion beam (FIB) marking for oxide defect localization using high resolution scanning electron microscopy (HRSEM), and transmission electron microscopy (TEM). By this technique, the damage strength associate with breakdown was evaluated with changing the breakdown stress current from micro to nano ampere for Poly-Si gate MOS capacitors which are fabricated on the boron doped substrate. The breakdown induced damage is strongly reduced below nano ampere. Under such a small damage regime, we observed the origin of the medium electric field breakdown for as-grown CZ wafers. It was an octahedral void, the same as that delineated by others using copper decoration method. To study for the failure mechanism of both grown-in and process-induced defects, we focused on the impact of Al or Poly-Si gate electrodes and oxide thickness on gate oxide integrity. Recent studies of the MOS capacitor gate oxide integrity B-mode failure ratios indicate a peak for an oxide thickness of either {}40 nm or from 70 to 100 nm. In present research, however, more precise analysis using commutative failure plots revealed that these peaks are artificial. It can be changed by the occurrence of self-healing. We found that grown-in defects have different degradation effect to Al and Poly-Si gate films, whereas oxygen precipitates have not. Finally we proposed the degradation model of grown-in voids and oxygen precipitates. Other fundamental topics are oxide defect annihilation and generation phenomena due to high temperature heat treatments. We have investigated B- and C-mode oxide defects and flow pattern (FP) and laser scattering tomography (LST) defects as a function of depth for hydrogen, argon, and dry oxygen ambient. The gate oxide strength depth profile of wafers after dry oxidation at 1200sp C was essentially homogeneous; whereas, for hydrogen and argon annealing ambient a variety of breakdown strength distributions were found. These oxide defect failure profiles were correlated with FPD and LSTD. The EBIC technique was used to delineate both B- and C-mode oxide failure sites. Subsequent one-to-one TEM observations of these EBIC defects marked by a focused ion beam revealed the origin of the B-mode oxide defect to be a residual void. Both qualitative and quantitative models based on point defect injection from the surface and the silicon bulk is proposed to explain the unique oxide defect distributions after hydrogen or argon annealing. In the summary, practical recommendation of suitable defect engineering options for the next ULSI era. is discussed.

Tamatsuka, Masaro

1997-12-01

187

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

National Technical Information Service (NTIS)

The authors examined the effect of oxidation on phosphorus-diffused crystalline-silicon p-type substrates. Oxidations subsequent to the phosphorus diffusion are of interest for passivating surfaces, and are commonly found in both high-efficiency laborator...

J. M. Gee R. R. King J. H. Reiss K. W. Mitchell S. Narayanan

1997-01-01

188

Silicon and tungsten oxide nanostructures for water splitting  

NASA Astrophysics Data System (ADS)

Inorganic semiconductors are promising materials for driving photoelectrochemical water-splitting reactions. However, there is not a single semiconductor material that can sustain the unassisted splitting of water into H2 and O2. Instead, we are developing a three part cell design where individual catalysts for water reduction and oxidation will be attached to the ends of a membrane. The job of splitting water is therefore divided into separate reduction and oxidation reactions, and each catalyst can be optimized independently for a single reaction. Silicon might be suitable to drive the water reduction. Inexpensive highly ordered Si wire arrays were grown on a single crystal wafer and transferred into a transparent, flexible polymer matrix. In this array, light would be absorbed along the longer axial dimension while the resulting electrons or holes would be collected along the much shorter radial dimension in a massively parallel array resembling carpet fibers on a microscale, hence the term "solar carpet". Tungsten oxide is a good candidate to drive the water oxidation. Self-organized porous tungsten oxide was successfully synthesized on the tungsten foil by anodization. This sponge-like structure absorbs light efficiently due to its high surface area; hence we called it "solar sponge".

Reyes Gil, Karla R.; Spurgeon, Joshua M.; Lewis, Nathan S.

2009-08-01

189

Atomic absorption spectroscopic measurements of silicon atom concentrations in electron cyclotron resonance silicon oxide deposition plasmas  

NASA Astrophysics Data System (ADS)

The silicon atom densities in both silane/oxygen and tetraethoxysilane (TEOS)/oxygen electron cyclotron resonance (ECR) plasmas were measured as functions of microwave power, pressure, and gas flow rates. An atomic absorption spectrometer with a Si hollow-cathode lamp was constructed for these measurements. Silicon atom densities in silane/oxygen ECR discharges increase with rising plasma density, and a strong correlation was found between the Si atom gas-phase abundance and the silicon oxide film deposition rate. The measured Si concentrations [(1-7)1010 cm-3] were high enough to account for a significant part of the film growth in the silane based chemistry. In TEOS/O2 discharges Si atom concentrations were lower by an order of magnitude, so Si is probably not a major contributor to the growth rate in that case. The internal temperature of Si atoms was found to vary from 380 to 720 K with increasing microwave power (200-650 W).

Augustyniak, Edward; Chew, Kok Heng; Shohet, J. Leon; Woods, R. Claude

1999-01-01

190

Vibrational spectroscopy characterization of magnetron sputtered silicon oxide and silicon oxynitride films  

NASA Astrophysics Data System (ADS)

Vibrational (infrared and Raman) spectroscopy has been used to characterize SiO xN y and SiO x films prepared by magnetron sputtering on steel and silicon substrates. Interference bands in the infrared reflectivity measurements provided the film thickness and the dielectric function of the films. Vibrational modes bands were obtained both from infrared and Raman spectra providing useful information on the bonding structure and the microstructure (formation of nano-voids in some coatings) for these amorphous (or nanocrystalline) coatings. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis have also been carried out to determine the composition and texture of the films, and to correlate these data with the vibrational spectroscopy studies. The angular dependence of the reflectivity spectra provides the dispersion of vibrational and interference polaritons modes, what allows to separate these two types of bands especially in the frequency regions where overlaps/resonances occurred. Finally the attenuated total reflection Fourier transform infrared measurements have been also carried out demonstrating the feasibility and high sensitivity of the technique. Comparison of the spectra of the SiO xN y films prepared in various conditions demonstrates how films can be prepared from pure silicon oxide to silicon oxynitride with reduced oxygen content.

Godinho, V.; Denisov, V. N.; Mavrin, B. N.; Novikova, N. N.; Vinogradov, E. A.; Yakovlev, V. A.; Fernndez-Ramos, C.; de Haro, M. C. Jimnez; Fernndez, A.

2009-10-01

191

Selective Growth of ?-Sexithiophene by Using Silicon Oxides Patterns  

PubMed Central

A process for fabricating ordered organic films on large area is presented. The process allows growing sexithiophene ultra-thin films at precise locations on patterned Si/SiOx substrates by driving the orientation of growth. This process combines the parallel local anodic oxidation of Si/SiOx substrates with the selective arrangement of molecular ultra-thin film. The former is used to fabricate silicon oxide arrays of parallel lines of 400 nm in width over an area of 1 cm2. Selective growth arises from the interplay between kinetic growth parameters and preferential interactions with the patterned surface. The result is an ultra-thin film of organic molecules that is conformal to the features of the fabricated motives.

Albonetti, Cristiano; Barbalinardo, Marianna; Milita, Silvia; Cavallini, Massimiliano; Liscio, Fabiola; Moulin, Jean-Francois; Biscarini, Fabio

2011-01-01

192

Comparative study between silicon-rich oxide films obtained by LPCVD and PECVD  

Microsoft Academic Search

A comparative study of compositional and optical properties of silicon-rich oxide (SRO) films deposited by low-pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD) is presented. Infrared spectra revealed the presence of hydrogen bonded to silicon atoms in the SROPECVD films, whereas in SROLPCVD films the IR spectra looked like the stoichiometric thermal silicon oxide. Moreover, X-ray photoelectron

A. Morales; J. Barreto; C. Domnguez; M. Riera; M. Aceves; J. Carrillo

2007-01-01

193

Dielectric function of annealed sub-stoichiometric silicon oxide layers  

NASA Astrophysics Data System (ADS)

We present an analytical methodology, based on electron energy loss spectroscopy and energy filtered transmission electron microscopy, which allow us to quantify the clustered silicon concentration and the complex dielectric function of annealed sub-stoichiometric silicon oxide layers, deposited by plasma enhanced chemical vapor deposition (PECVD). To put in evidence the Si clusters, formed as a consequence of the high temperature anneal and embedded in a SiO2 host, we used energy selected bright field imaging with an energy loss tuned to the value of the Si bulk plasmon. The dielectric function of the sample is determined by fitting the experimental spectrum using the theoretical description proposed by Barrera and Fuchs(1). The model solves the problem of calculating the energy loss rate for electrons passing through a system of spherical particles of equal radii, located at random in a host material. The dielectric function of the host was preliminarily determined by a Kramers-Kronig analysis of reference pure PECVD oxide spectrum. (1) R.G. Barrera and R. Fuchs, Phys. Rev. B52, 3256 (1995)

Rimini, Emanuele

2005-03-01

194

Isotopic fractionation effects under laser ablation of silicon from pure silicon and silicon oxide targets  

NASA Astrophysics Data System (ADS)

The isotopic and elemental composition of bodies in the solar system is of great interest due to the information it will yield as to the formation and evolution of the bodies and the solar system in general. One possible method to quickly measure isotopic ratios on airless bodies is to use laser ablation coupled with ion mass spectrometry at a stand off distance. Specifically a Nd:YAG laser operating at 1.064mum was used to ablate the target and the resulting plasma was measured with a time of flight mass spectrometer (TOFMS) placed >3m away from the target. The detector used was a Ceramic Channel Electron Multiplier (CCEM) with an Electro-Static Analyzer (ESA) for ion energy selection. This set up allowed the measurement of mass spectrums from a variety of targets with ion energies running from 25 eV to 1 KeV created by laser energy densities from 21 to 77 J/cm2. Because of a non-linear response of the CCEM, the relative amounts of the different isotopes could not be accurately compared, as the more abundant isotopes flux rate causes the CCEM to respond with a lower gain per particle then less abundant isotopes, yielding an apparent enhancement in the minor isotopes. This saturation effect was proven by comparing the ion flux measured by the CCEM to that measured by a faraday cup from an aluminum target. However, by making comparisons between the flux measured by the faraday cup and the changes in isotopic ratios observed in the CCEM data for silicon targets, a trend appears which is independent of ion energy or laser fluence, indicating that any fractionation is caused by a process which is independent of laser fluence and ion energy. Further, by making comparisons between the measured major isotope flux and the changes in isotopic ratios for both silicon and SiO2, another trend emerges, namely independence from materials. Finally, several changes must be made to the proposed instrument to make it viable for exploration purposes, most importantly a detector with a wider dynamic range in incident flux must be chosen to make accurate measurements of isotopic ratios.

Shappirio, Mark

195

Wet chemical surface functionalization of oxide-free silicon  

NASA Astrophysics Data System (ADS)

Silicon is by far the most important semiconductor material in the microelectronic industry mostly due to the high quality of the Si/SiO2 interface. Consequently, applications requiring chemical functionalization of Si substrates have focused on molecular grafting of SiO2 surfaces. Unfortunately, there are practical problems affecting homogeneity and stability of many organic layers grafted on SiO2, such as silanes and phosphonates, related to polymerization and hydrolysis of Si-O-Si and Si-O-P bonds. These issues have stimulated efforts in grafting functional molecules on oxide-free Si surfaces, mostly with wet chemical processes. This review focuses therefore directly on wet chemical surface functionalization of oxide-free Si surfaces, starting from H-terminated Si surfaces. The main preparation methods of oxide-free H-terminated Si and their stability are first summarized. Functionalization is then classified into indirect substitution of H-termination by functional organic molecules, such as hydrosilylation, and direct substitution by other atoms (e.g. halogens) or small functional groups (e.g. OH, NH2) that can be used for further reaction. An emphasis is placed on a recently discovered method to produce a nanopattern of functional groups on otherwise oxide-free, H-terminated and atomically flat Si(1 1 1) surfaces. Such model surfaces are particularly interesting because they make it possible to derive fundamental knowledge of surface chemical reactions.

Thissen, Peter; Seitz, Oliver; Chabal, Yves J.

2012-09-01

196

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

NASA Astrophysics Data System (ADS)

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.

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

2007-11-01

197

Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation  

NASA Astrophysics Data System (ADS)

A leading approach for large-scale electrochemical energy production with minimal global-warming gas emission is to use a renewable source of electricity, such as solar energy, to oxidize water, providing the abundant source of electrons needed in fuel synthesis. We report corrosion-resistant, nanocomposite anodes for the oxidation of water required to produce renewable fuels. Silicon, an earth-abundant element and an efficient photovoltaic material, is protected by atomic layer deposition (ALD) of a highly uniform, 2?nm thick layer of titanium dioxide (TiO2) and then coated with an optically transmitting layer of a known catalyst (3?nm iridium). Photoelectrochemical water oxidation was observed to occur below the reversible potential whereas dark electrochemical water oxidation was found to have low-to-moderate overpotentials at all pH values, resulting in an inferred photovoltage of ~550?mV. Water oxidation is sustained at these anodes for many hours in harsh pH and oxidative environments whereas comparable silicon anodes without the TiO2 coating quickly fail. The desirable electrochemical efficiency and corrosion resistance of these anodes is made possible by the low electron-tunnelling resistance (<0.006???cm2 for p+-Si) and uniform thickness of atomic-layer deposited TiO2.

Chen, Yi Wei; Prange, Jonathan D.; Dhnen, Simon; Park, Yohan; Gunji, Marika; Chidsey, Christopher E. D.; McIntyre, Paul C.

2011-07-01

198

Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation.  

PubMed

A leading approach for large-scale electrochemical energy production with minimal global-warming gas emission is to use a renewable source of electricity, such as solar energy, to oxidize water, providing the abundant source of electrons needed in fuel synthesis. We report corrosion-resistant, nanocomposite anodes for the oxidation of water required to produce renewable fuels. Silicon, an earth-abundant element and an efficient photovoltaic material, is protected by atomic layer deposition (ALD) of a highly uniform, 2 nm thick layer of titanium dioxide (TiO(2)) and then coated with an optically transmitting layer of a known catalyst (3 nm iridium). Photoelectrochemical water oxidation was observed to occur below the reversible potential whereas dark electrochemical water oxidation was found to have low-to-moderate overpotentials at all pH values, resulting in an inferred photovoltage of ~550 mV. Water oxidation is sustained at these anodes for many hours in harsh pH and oxidative environments whereas comparable silicon anodes without the TiO(2) coating quickly fail. The desirable electrochemical efficiency and corrosion resistance of these anodes is made possible by the low electron-tunnelling resistance (<0.006 ? cm(2) for p(+)-Si) and uniform thickness of atomic-layer deposited TiO(2). PMID:21685904

Chen, Yi Wei; Prange, Jonathan D; Dhnen, Simon; Park, Yohan; Gunji, Marika; Chidsey, Christopher E D; McIntyre, Paul C

2011-06-19

199

Silicon oxidation and Si--SiO/sub 2/ interface of thin oxides  

SciTech Connect

High-resolution transmission electron microscopy (HRTEM) and ellipsometry techniques have been employed to measure thicknesses of silicon oxide, grown at 800 /sup 0/C in dry oxygen, in the thickness range of 2--20 nm. While the oxide growth data measured from TEM obey a nearly linear behavior, those obtained from ellipsometry are seen to vary nonlinearly. The interface structure as function of the increasing oxide thickness was studied using HRTEM. At these oxidation temperatures, the earlier reported variations of roughness at the interface on the oxide thickness for oxides grown at 900 /sup 0/C are not seen. Attempts aimed at correlating the high-resolution transmission electron micrographs with some physical parameters like the refractive index and the dielectric breakdown lead to considerations of the importance of the effect of protrusions of silicon atoms of 1 mm size into SiO/sub 2/ layers on the interface properties. These findings lead to explanations of some key features concerning the refractive index and density of thin SiO/sub 2/.

Ravindra, N.M.; Narayan, J.; Fathy, D.; Srivastava, J.K.; Irene, E.A.

1987-03-01

200

Visible light photocatalytic degradation of dyes by bismuth oxide-reduced graphene oxide composites prepared via microwave-assisted method.  

PubMed

Bi2O3-reduced graphene oxide (RGO) composites were successfully synthesized via microwave-assisted reduction of graphite oxide in Bi2O3 precursor solution using a microwave system. Their morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) and methyl orange (MO) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, UV-vis absorption spectroscopy, and electrochemical impedance spectroscopy, respectively. The results show that the RGO addition can enhance the photocatalytic performance of Bi2O3-RGO composites. Bi2O3-RGO composite with 2 wt.% RGO achieves maximum MO and MB degradation rates of 93% and 96% at 240min under visible light irradiation, respectively, much higher than those for the pure Bi2O3 (78% and 76%). The enhanced photocatalytic performance is ascribed to the increased light adsorption and the reduction in electron-hole pair recombination in Bi2O3 with the introduction of RGO. PMID:23953652

Liu, Xinjuan; Pan, Likun; Lv, Tian; Sun, Zhuo; Sun, Chang Q

2013-07-27

201

Influence of interfacial copper on the room temperature oxidation of silicon  

SciTech Connect

Thick ({approximately}1.3 {mu}m) oxide films were grown by room-temperature oxidation of silicon after low-energy copper-ion implantation. The structural properties of the silicon dioxide layer and the implanted silicon were characterized by Rutherford backscattering spectrometry and transmission-electron microscopy. During the room temperature oxidation a portion of the implanted copper resided on the surface and a portion moved with the advancing Si/SiO{sub 2} interface. This study revealed that the oxide growth rate was dependent on the amount of Cu present at the moving interface. The surface copper is essential for the dissociation of oxygen at the surface, and it is this oxygen that participates in the oxidation process. The resulting oxide formed was approximately stoichiometric silicon dioxide. {copyright} {ital 1996 American Institute of Physics.}

Alford, T.L.; Jaquez, E.J.; Theodore, N.D.; Russell, S.W.; Diale, M.; Adams, D. [Chemical, Bio, and Materials Engineering, Arizona State University, Tempe, Arizona 85287-6006 (United States); Anders, S. [Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)

1996-02-01

202

Synthesis of Silicon and Zinc Oxide Nanowhiskers and Studies of Their Properties  

NASA Astrophysics Data System (ADS)

The conditions and mechanisms for purposeful pattern formation on the surface of single-crystal silicon wafers by building up silicon or zinc oxide by the vapor-liquid-crystal (VLC) mechanism were studied. For the polished silicon surface we developed a procedure for preparation of areas with randomly distributed nanosized gold metal particles - whisker growth initiators. The arrays of randomly distributed silicon and zinc oxide whiskers were grown. The emission cells with a pointed surface pattern were fabricated. The morphology, structure, and field electron emission properties of the fabricated structures were studied.

Gorbyk, P. P.; Dubrovin, I. V.; Dadykin, A. A.; Demchenko, Yu. A.

203

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

204

Low Dielectric Constant Interlayer Using Fluorine-Doped Silicon Oxide  

NASA Astrophysics Data System (ADS)

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 Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Low dielectric constants caused by Si F bond formation and good gap-filling ability due to in situ etching by C2F6 plasma are obtained. Therefore, SiOF film has very high applicability as an interlayer dielectric film for advanced VLSI devices.

Usami, Takashi; Shimokawa, Kimiaki; Yoshimaru, Masaki

1994-01-01

205

LPCVD Si3N4 growth retardation on silicon native oxide compared with in situ HF vapour-deglazed silicon substrates  

Microsoft Academic Search

The advantages offered by clustered tools, which eliminate parasitic oxidation of silicon as currently observed in classical open furnaces, allow for a more in-depth study of the influence of a complete native oxide deglaze on the silicon nitride deposition. In this study it is found that silicon wafers, kept under vacuum without native oxide etching, tend to show Si3N4 growth

F. Martin; F. Bertin; H. Sprey; E. Granneman

1991-01-01

206

Electron beam induced current analysis of metal oxide silicon structures  

NASA Astrophysics Data System (ADS)

This thesis presents the history and the development of the scanning electron microscopy (SEM) of Metal-Oxide-Silicon structures by the Electron-Beam-Induced-Current technique (MOS/EBIC) through the year 1997. General experimental results are described which reveal the behavior of MOS capacitor structures under the influence of electron beam irradiation as well as the developments which led in a very natural way to a merging of EBIC imaging techniques and the analytical work on irradiated MOS capacitors to create the field of MOS/EBIC diagnostic imaging. Also included is a review of circuit and electromagnetic field theory as it relates to materials systems. Specific new results and contributions of this research are also described. Although previous researchers have provided rather exhaustive lists of electrical inhomogeneities which might give rise to contrast in EBIC images of MOS capacitors, they did not provide a detailed methodology for separating the various contrast mechanisms. The conventions and techniques described herein, however, present a clear framework from which to decide the origin of MOS/EBIC contrast under accumulation, depletion/inversion and transition biasing conditions. The bias-dependent contrast behavior of breakdown sites are also described. In addition,novel applications for using MOS/EBIC to analyze and delineate defects in semiconductor silicon are presented herein. The major finding on as-grown wafers is that B-mode failures in MOS capacitors were primarily attributed to vacancy clusters or voids of 0.1 to 0.3 mum in size. It is also shown that shallow substrate and Si/SiOsb2 interfacial defects not. detectable by conventional EBIC could be detected by MOS/EBIC, using transition bias contrast. This contrast analysis technique is described in some detail in chapters five and six. In particular, damage associated with implantation in SIMOX wafers as well as that associated with the reactive-ion-etching of pre-oxidized Si substrates is analyzed, using transmission bias techniques.

Kirk, Harry Robert

1998-11-01

207

Optical radiative parameters and 1.3?m emission anticipation of Pr in two kinds of bismuth-containing oxide glasses with lower phonon energies  

NASA Astrophysics Data System (ADS)

Trivalent praseodymium ions were added in bismuth-containing tellurite (LKBBT) and gallate (LKBBG) glasses to develop potential oxide glass amplifier medium operating at 1.3?m. Based on optical absorptions, three phenomenological Judd-Ofelt parameters ?2, ?4 and ?6 of Pr have been derived to be 4.1410, 6.8810 and 4.7110cm in LKBBT system, and 3.8510, 7.2010 and 3.1010cm in LKBBG system, respectively. Large ?2 values indicate higher asymmetry and stronger covalent environment in them. The branching ratios for G41?H53 transition of Pr in the two glass systems arrive at 60.5% and 56.9%, respectively, and the predicted spontaneous-radiative transition rates are as high as 1188 and 1112s, which are beneficial in achieving efficient 1.3?m emission under the pumping of 1.03?m laser sources.

Zhang, Y. Y.; Chen, B. J.; Pun, E. Y. B.; Lin, H.

2009-05-01

208

Effects of natural and electrochemical oxidation processes on acoustic waves in porous silicon films  

NASA Astrophysics Data System (ADS)

Brillouin scattering has been performed to study the effects of natural and electrochemical oxidation on the surface and bulk acoustic mode properties of porous silicon films. The acoustic mode frequencies are observed to decrease with increasing oxidation time and this is attributed to the progressive transformation of silicon-silicon bonds on the inner pore walls into SiO2. The dependence of the surface and bulk acoustic mode frequencies on the natural oxidation time allows the evaluation of these wave frequencies for a porous-SiO2 glass film, and hence the estimation of its bulk modulus. Both Brillouin and Raman data confirm the expectation that oxidation leads to a reduction in silicon nanoparticle size, and provide a correlation between the redsifted acoustic mode frequency and the oxidation period.

Fan, H. J.; Kuok, M. H.; Ng, S. C.; Lim, H. S.; Liu, N. N.; Boukherroub, R.; Lockwood, D. J.

2003-07-01

209

Photoluminescence from OH-related radiative centres in silica, metal oxides and oxidized nanocrystalline and porous silicon  

Microsoft Academic Search

It is shown that the green\\/blue photoluminescence from oxidized nanocrystalline and porous silicon, which has been attributed to the blue shift of the band gap in small silicon nanocrystals, is due to silanol groups; ?Si?OH. Alanol groups, ? Al?OH and hydrated lead oxide, PbO2(OH) show the same photoluminescence in terms of spectral distribution and fast decay time of several nanoseconds.

M. Rckschloss; Th. Wirschem; H. Tamura; G. Ruhl; J. Oswald; S. Vep?ek

1995-01-01

210

Study of the effect of neutron damage on anodic oxidation of monocristalline silicon solar cells for the purpose of determining phosphorus concentration depth profile using neutron activation analysis  

Microsoft Academic Search

Neutron activation analysis for the determination of phosphorus concentration depth profile in monocristalline silicon solar cells, requires known thicknesses of silicon oxide grown on the irradiated silicon sample by anodic oxidation. These are then etched by an HF solution which is measured for the ? radioactivity of P32. The thickness of silicon oxide formed by anodic oxidation is known by

Z. Idiri; M. Belamri; A. Azbouche; A. Badredine; C. Lakhdar Chaouch; M. Imadalou; B. Palahouane; M. Boumaour; A. Maallemi; B. Guediura

2007-01-01

211

Raman scattering study on pristine and oxidized n-type porous silicon  

NASA Astrophysics Data System (ADS)

We have investigated the effects of oxidation on Raman spectra of porous silicon (PS). Many Si-H x bonds were indicated in as-anodized PS. Compared to crystalline silicon, the background in the spectrum was stronger which indicates that the PS surface was rough due to the presence of pores. When oxidation was performed, the Raman spectrum revealed the presence of nanocrystalline silicon in freshly prepared PS whose diameter was around 5.22 nm. The Raman analysis showed that the peak intensities sharply decrease after oxidation compared to the as-prepared because the bonds of Si-H x on the PS surface are greatly reduced after oxidation. The oxidation of PS by thermal oxidation is complete; therefore, thermal oxidation is very well suited for a passivation of PS films.

Zhong, Furu; JIA, Zhen-hong

2013-02-01

212

Brewster-angle analysis of native and photoelectrochemically grown silicon oxide nanotopographies  

Microsoft Academic Search

Brewster-angle reflectometry (BAR) is employed in-situ for the first time for investigation of the silicon oxide\\/silicon system during photocurrent oscillations in fluorine containing solution. Combining ex-situ Brewster-angle analysis (BAA) and atomic force microscopy (AFM) shows oxide thickness variations between 4.8 and 13.8nm. The anodic oxide etch rate amounts to 0.1nms?1 in contrast to 0.01nms?1 for native oxide. The ambient\\/anodic oxide

M. Lublow; H. J. Lewerenz

2007-01-01

213

X-ray reflectivity study of formation of multilayer porous anodic oxides of silicon.  

SciTech Connect

The paper reports data on the kinetics of anodic oxide films growth on silicon in aqueous solutions of phosphoric acids as well as a study of the morphology of the oxides grown in a special regime of the oscillating anodic potential. X-ray reflectivity measurements were performed on the samples of anodic oxides using an intense synchrotron radiation source. They have a multilayer structure as revealed by theoretical fitting of the reflectivity data. The oscillations of the anodic potential are explained in terms of synchronized oxidation/dissolution reactions at the silicon surface and accumulation of mechanic stress in the oxide film.

Chu, Y.; Fenollosa, R.; Parkhutik, V.; You, H.

1999-07-21

214

Oxidation of Germanium and Silicon surfaces (100): a comparative study through DFT methodology  

NASA Astrophysics Data System (ADS)

Density Functional Theory calculations are used to map out the preferential oxygen molecule adsorption sites and oxygen atom incorporation on germanium (100) surface. A comparison with primary oxidation mechanisms encountered in pure silicon and silicon germanium (100) surfaces is presented here. This study highlights opposite substrates behaviors facing oxygen molecule adsorption: 1/ surface germanium atoms move from their crystalline positions to adapt to the approaching oxygen molecule resulting in adsorbed peroxide bridge configuration, whereas oxygen molecule is fully dissociated in strand configuration on a silicon surface 2/ oxygen atoms tend to avoid each other on germanium surface whereas oxide nucleus can be observed on silicon surface even at the early steps of the oxidation process. Results show that germanium surface appears to be less reactive than the silicon substrate towards molecular oxygen species.

Mastail, C.; Bourennane, I.; Estve, A.; Landa, G.; Djafari Rouhani, M.; Richard, N.; Hmeryck, A.

2012-12-01

215

Mechanical properties of PECVD silicon oxide films suitable for integrated optics applications  

Microsoft Academic Search

Silicon oxide films are deposited on silicon wafers by PECVD from SiH4 and N2O at different values of the deposition parameters. The refractive index is found to vary with gas flow ratio (R), making these films suitable for a silicon-based integrated optics technology. The films are submitted to annealing processes on inert atmosphere in order to facilitate the impurity effusion,

Jose A. Rodriguez; Carlos Dominguez-Tagle; Francisco J. Munoz; Andreu Llobera

2000-01-01

216

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

Microsoft Academic Search

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.

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

1997-01-01

217

Characterization of the mechanism of bi-layer oxide growth on austenitic stainless steels 316L and D9 in oxygen-controlled Lead-Bismuth Eutectic (LBE)  

NASA Astrophysics Data System (ADS)

Lead Bismuth Eutectic (LBE) has been proposed for use in programs for accelerator-based and reactor-based transmutation of nuclear waste. LBE is a leading candidate material as a spallation target (in accelerator-based transmutation) and an option for the sub-critical blanket coolant. The corrosion by LBE of annealed and cold-rolled 316L stainless steels, and the modified austenitic stainless steel alloy D9, has been studied using Scanning Electron Microscopy (SEM), Electron Probe Micro Analysis (EPMA), and X-ray Photoelectron Spectroscopy (XPS). Exposed and unexposed samples have been compared and the differences studied. Small amounts of surface contamination are present on the samples and have been removed by ion-beam sputtering. The unexposed samples reveal typical stainless steel characteristics: a chromium oxide passivation surface layer and metallic iron and nickel. The exposed samples show protective iron oxide and chromium oxide growths on the surface. Oxygen takes many forms on the exposed samples, including oxides of iron and chromium, carbonates, and organic acids from subsequent handling after exposure to LBE. Different types of surface preparation have lead to considerably different modes of corrosion. The cold-rold samples were resistant to thick oxide growth, having only a thin (< 1 mum), dense chromium-rich oxide. The annealed 316L and D9 samples developed thick, bi-layered oxides, the inner layer consisting of chromium-rich oxides (likely spinel) and the outer layer consisting mostly of iron oxides. The cold-rolled samples were able to maintain a thin chromium oxide layer because of the surface work performed on it, as ample diffusion pathways provided an adequate supply of chromium atoms. The annealed samples grew thick oxides because iron was the primary diffusant, as there are fewer fast-diffusion pathways and therefore an amount of chromium insufficient to maintain a chromium based oxide. Even the thick oxide, however, can prolong the life of a steel in LBE, provided proper oxygen control. The mechanisms responsible for the differences in the oxidation behaviors are discussed.

Koury, Daniel

218

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

NASA Astrophysics Data System (ADS)

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.

Frey, Eric Charles

219

Role of oxidizing agent: thin film formation by photo-oxidizing silicone oil for vacuum UV rays transmittance and high hardness  

NASA Astrophysics Data System (ADS)

An oxidizing agent is needed for silicone oil to be photo-oxidized with Xe2 excimer-lamp. However, the lamp light did not reach the silicone oil on the surface of the substrate satisfactorily, and the photo-oxidation reaction of the silicone oil layer was hard to take place properly. In order to find the appropriate conditions for supplying the proper amount of an oxidizing agent to silicone oil, the vacuum ultraviolet light that passed the silicone oil layer was made fluoresce in the phosphor to monitor the progress of the photo-oxidation reaction. As the vitrification by photo-oxidation reaction of the silicone oil layer improved, the fluorescence intensity of the phosphor increased. While monitoring the change of the fluorescence intensity, the supply of the oxidizing agent and the irradiation time of the vacuum ultraviolet light were controlled; as a result, the new method to efficiently form a transparent, photo-oxidized thin film has been established.

Murahara, M.; Sato, Y.; Jitsuno, T.; Okamoto, Y.

2012-11-01

220

Native Oxide Growth on Silicon Surface in Ultrapure Water and Hydrogen Peroxide  

Microsoft Academic Search

The effects of n-type dopant (P, As) concentration in silicon (100), temperature, and oxidizing species on native oxide growth in liquid water are described. The oxide growth on phosphorus (P)- and arsenic (As)-doped n+-Si surfaces (1020 cm-3) in ultrapure water exhibits saturation of oxide thickness, suggesting a field-assisted mechanism. Oxide thickness saturation was also found on n-Si in hydrogen peroxide

Mizuho Morita; Tadahiro Ohmi; Eiji Hasegawa; Akinobu Teramoto

1990-01-01

221

Simultaneous achievement of high-quality oxide passivation of nc-Si and suppression of Er de-activation by silicon-rich silicon oxide \\/ Er-doped silicon nitride multilayers  

Microsoft Academic Search

The effect of nc-Si\\/Er environment is investigated. We find that by using a silicon-rich silicon-oxide\\/SiN:Er multilayers, high quality nc-Si passivation and suppression of Er de-activation can be achieved simultaneously for optimal Er luminescence.

In Yong Kim; J. H. Shin; Kyung Joon Kim; Moon-Seung Yang

2008-01-01

222

The Effect of Thermal Oxidation of Silicon on Boron Diffusion in Extrinsic Conditions  

NASA Astrophysics Data System (ADS)

Boron diffusion during extrinsic conditions in silicon has been investigated under both oxidizing and inert atmospheres for different temperatures (950-1100C) and times. Oxidation-enhanced diffusion (OED) was found. This result is opposite to the oxidation-retarded diffusion of arsenic case.

Ishikawa, Yutaka; Nakamichi, Ichiro; Matsumoto, Satoru; Niimi, Tatsuya

1987-09-01

223

Low temperature silicon direct bonding for application in micromechanics: bonding energies for different combinations of oxides  

Microsoft Academic Search

Plain or structured hydrophillic silicon wafers covered with native oxide or with thermally grown oxide layers have been directly bonded at room temperature; afterwards, the samples were annealed at 100C to 400C. There is a significant difference in the observed bonding energy depending on the wafer pairing chosen. If one or both wafers are covered with a native oxide layer,

Gertrud Kruter; Andreas Schumacher; Ulrich Gsele

1998-01-01

224

X-ray reflectivity study of formation of multilayer porous anodic oxides of silicon  

Microsoft Academic Search

The paper reports data on the kinetics of anodic oxide films growth on silicon in aqueous solutions of phosphoric acids as well as a study of the morphology of the oxides grown in a special regime of the oscillating anodic potential. X-ray reflectivity measurements were performed on the samples of anodic oxides using an intense synchrotron radiation source. They have

R Fenollosa; H You; Y Chu; V Parkhutik

2000-01-01

225

Silicon nanoprofiling with the use of a solid aluminum oxide mask and combined 'dry' etching  

SciTech Connect

Technological features of nanoprofiling of silicon protected by a solid mask based on porous aluminum oxide are considered. It is shown that, for a nanoprofiled silicon surface to be formed, it is advisable that combined dry etching be used including preliminary bombardment of structures with accelerated neutral atoms of an inert gas followed by reactive ion etching.

Belov, A. N.; Demidov, Yu. A.; Putrya, M. G. [Moscow Institute of Electronic Engineering (Technical University) (Russian Federation); Golishnikov, A. A., E-mail: A.Golishnikov@tcen.ru [Moscow Institute of Electronic Engineering, Technological Center for Research and Production Company (Russian Federation); Vasilyev, A. A. [Laboratory of Microdevices Limited Liability Company (Russian Federation)

2009-12-15

226

Initial stage of native oxide growth on hydrogen terminated silicon (111) surfaces  

Microsoft Academic Search

We investigated the initial stage of native oxide growth on an atomically flat hydrogen terminated silicon (Si) (111) surface by immersion in pure water using Fourier transformed infrared attenuated total reflection spectroscopy and reflection absorption spectroscopy. There is a sharp absorption peak at 2083 cm?1 arising from silicon monohydrides at surface terraces, this peak decreases and broadens with immersion time

Hiroki Ogawa; Kenji Ishikawa; Carlos Inomata; Shuzo Fujimura

1996-01-01

227

New effects in the kinetics of the electrochemical oxidation of silicon  

Microsoft Academic Search

The present work describes new effects in the kinetics of the electrochemical oxidation of silicon observed recently by the author. One is the observation of very large oscillations of anodic potential during anodization of silicon in H3PO4\\/HF electrolyte and another is the effect of externally applied mechanical stress onto the kinetics of the Si anodization in concentrated and diluted HF.

Vitali Parkhutik

2000-01-01

228

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

NASA Astrophysics Data System (ADS)

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 in the case of control hafnium oxide and SiO2 structures. It was believed that Si dissociation from the HfSiON layer was the main reason for the positive Vfb shift and the EOT decrease.

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

2005-05-01

229

Direct Observation of the Precession of Individual Paramagnetic Spins on Oxidized Silicon Surfaces.  

National Technical Information Service (NTIS)

The precession of individual spins on partially oxidized Si(111) (Silicon) surfaces has been detected using a scanning tunneling microscope. The spin precession in a constant magnetic field induces a modulation in the tunneling current at the Larmor frequ...

Y. Manassen R. J. Hamers J. E. Demuth A. J. Castellano

1990-01-01

230

Large area nanoscale patterning of silicon surfaces by parallel local oxidation.  

PubMed

The homogeneity and the reproducibility of parallel local oxidation have been improved by introducing a thin film of polymethylmethacrylate (PMMA) between the stamp and the silicon surface. The flexibility of the polymer film enables a homogeneous contact of the stamp with the silicon surface to be achieved. The oxides obtained yield better aspect ratios compared with the ones created with no PMMA layer. The pattern is formed when a bias voltage is applied between the stamp and the silicon surface for 1 min. The patterning can be done by a step and repeat technique and is reproducible across a centimetre length scale. Once the oxide nanostructures have been created, the polymer is removed by etching in acetone. Finally, parallel local oxidation is applied to fabricate silicon nanostructures and templates for the growth of organic molecules. PMID:19875876

Losilla, N S; Martnez, J; Garca, R

2009-10-29

231

Evolution of relief of asperited polycrystalline silicon surface in the process of thermal oxidation  

Microsoft Academic Search

A simple phenomenological model of changing asperity surface, in the process of thermal oxidation of polycrystalline silicon, is examined. This allows to prognosticate and consequently deliberately change electrical characteristics of the dielectric layer

G. V. Perov; E. G. Salman; A. N. Ignatov

2000-01-01

232

Synchrotron x-ray reflectivity study of oxidation/passivation of copper and silicon.  

National Technical Information Service (NTIS)

Synchrotron x-ray-scattering technique studies of copper and silicon electrochemical interfaces are reported. These two examples illustrate the application of synchrotron x-ray techniques for oxidation, passivation, and dissolution of metals and semicondu...

Y. Chu Z. Nagy V. Parkhutik H. You

1999-01-01

233

Maskless lithography using silicon oxide etch-stop layer induced by megahertz repetition femtosecond laser pulses.  

PubMed

In this study we report a new method for maskless lithography fabrication process by a combination of direct silicon oxide etch-stop layer patterning and wet alkaline etching. A thin layer of etch-stop silicon oxide of predetermined pattern was first generated by irradiation with high repetition (MHz) ultrafast (femtosecond) laser pulses in air and at atmospheric pressure. The induced thin layer of silicon oxide is used as an etch stop during etching process in alkaline etchants such as KOH. Our proposed method has the potential to enable low-cost, flexible, high quality patterning for a wide variety of application in the field of micro- and nanotechnology, this technique can be leading to a promising solution for maskless lithography technique. A Scanning Electron Microscope (SEM), optical microscopy, Micro-Raman, Energy Dispersive X-ray (EDX) and X-ray diffraction spectroscopy were used to analyze the silicon oxide layer induced by laser pulses. PMID:21643340

Kiani, Amirkianoosh; Venkatakrishnan, Krishnan; Tan, Bo; Venkataramanan, Venkat

2011-05-23

234

Structural And Optical Properties Of Silicon Nanocrystals Embedded In Silicon Oxide Films  

Microsoft Academic Search

\\u000a The photoluminescence properties of silicon nanostructured materials are strongly influenced by thermal treatments. To develop\\u000a silicon based room temperature light emitting materials in addition to porous silicon fabricated by anodization, other kinds\\u000a of films fabricated by sputtering, gas vaporization, and chemical vapor deposition were investigated [1]. Thermal treatments have different influences upon these structures: porous silicon is stabilized and its

M. Miu; A. Angelescu; I. Kleps; M. Simion; A. Bragaru

235

Auger parameter determination of bonding states on thinly oxidized silicon nitride  

SciTech Connect

Silicon nitride powders have been thermally oxidized between 700 and 1,200 C in a high purity N{sub 2}--20% O{sub 2} gas environment. The powders were subsequently analyzed by x-ray photoelectron and Auger electron spectroscopy for evidence of oxynitride surface states. Measurements were made on the Si 2p, O 1s, N 1s, C 1s, F 1s, and Si KLL transitions, the latter being obtained using bremsstrahlung radiation from the Mg x-ray source. As a function of increasing temperature the data show a clear progression of spectral binding energies and peak shapes that are indicative of more advanced surface oxidation. However, definitive analysis of these data rests on the combined use of both Auger and photoelectron data to define the oxidized surface states for a system that involves two electrically insulating end states, silicon nitride and silicon dioxide. Curve fitting the Si 2p and Si KLL transitions as a function of oxidation, coupled with use of Auger parameters for the starting silicon nitride and final silicon dioxide, reveals no measurable evidence for an interphase oxynitride in the thin oxide scales of this study, where the silicon nitride substrate is detectable. Possible incorrect assignment of oxynitride bonding, from shifted Si 2p states in the carbon referenced spectra, is attributable to band bending as the transition is made from incipient to fully formed silicon dioxide.

Taylor, T.N.; Butt, D.P. [Los Alamos National Lab., NM (United States); Pantano, C.G. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

1997-10-01

236

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

DOEpatents

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.

Natesan, Ken (Naperville, IL)

1994-01-01

237

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

DOEpatents

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.

Natesan, K.

1994-12-27

238

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

DOEpatents

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.

Natesan, K.

1992-01-01

239

Catalyzed-assisted growth of well-aligned silicon oxide nanowires  

Microsoft Academic Search

Bulk quantity and ultra-long silicon oxide nanowires on micrometer-sized solid tin balls have been synthesized by typical chemical vapor deposition via a vaporliquidsolid process. Low melting point tin droplets can be used as an effective catalyst for the large-scale growth of highly aligned silicon oxide nanowires. Observations using scanning electron microscopy indicate that numerous nanowires simultaneously nucleate, grow at nearly

Jun Zhang; Baolong Xu; Yongdong Yang; Feihong Jiang; Jianping Li; Xichang Wang; Shumei Wang

2006-01-01

240

Directional deposition of dielectric silicon oxide by plasma enhanced TEOS process  

Microsoft Academic Search

A description is given of the deposition of dielectric silicon oxide from TEOS in helium\\/oxygen mixtures in a parallel-plate RF plasma reactor. Under appropriate process conditions, highly directional deposition of low-stress stoichiometric silicon oxide is achieved. The step coverage profiles and the chemical and physical properties of these SiO2 films were studied to gain an understanding of the origin of

J. J. Hsieh; D. E. Ibbotson; J. A. Mucha; D. L. Flamm

1989-01-01

241

Thromboresistance characterization of extruded nitric oxide-releasing silicone catheters.  

PubMed

Intravascular catheters used in clinical practice can activate platelets, leading to thrombus formation and stagnation of blood flow. Nitric oxide (NO)-releasing polymers have been shown previously to reduce clot formation on a number of blood contacting devices. In this work, trilaminar NO-releasing silicone catheters were fabricated and tested for their thrombogenicity. All catheters had specifications of L = 6 cm, inner diameter = 21 gauge (0.0723 cm), outer diameter = 12 gauge (0.2052 cm), and NO-releasing layer thickness = 200 11 m. Control and NO-releasing catheters were characterized in vitro for their NO flux and NO release duration by gas phase chemiluminescence measurements. The catheters were then implanted in the right and left internal jugular veins of (N = 6 and average weight = 3 kg) adult male rabbits for 4 hours thrombogenicity testing. Platelet counts and function, methemoglobin (metHb), hemoglobin (Hb), and white cell counts and functional time (defined as patency time of catheter) were monitored as measured outcomes. Nitric oxide-releasing catheters (N = 6) maintained an average flux above (2 0.5) 10(-10) mol/min/cm for more than 24 hours, whereas controls showed no NO release. Methemoglobin, Hb, white cell, and platelet counts and platelet function at 4 hours were not significantly different from baseline (? = 0.05). However, clots on controls were visibly larger and prevented blood draws at a significantly (p < 0.05) earlier time (2.3 0.7 hours) into the experiment, whereas all NO-releasing catheters survived the entire 4 hours test period. Results indicate that catheter NO flux levels attenuated thrombus formation in a short-term animal model. PMID:22395119

Amoako, Kagya A; Archangeli, Christopher; Handa, Hitesh; Major, Terry; Meyerhoff, Mark E; Annich, Gail M; Bartlett, Robert H

242

Alternative method for steam generation for thermal oxidation of silicon  

NASA Astrophysics Data System (ADS)

Thermal oxidation of silicon is an important process step in MEMS device fabrication. Thicker oxide layers are often used as structural components and can take days or weeks to grow, causing high gas costs, maintenance issues, and a process bottleneck. Pyrolytic steam, which is generated from hydrogen and oxygen combustion, was the default process, but has serious drawbacks: cost, safety, particles, permitting, reduced growth rate, rapid hydrogen consumption, component breakdown and limited steam flow rates. Results from data collected over a 24 month period by a MEMS manufacturer supports replacement of pyrolytic torches with RASIRC Steamer technology to reduce process cycle time and enable expansion previously limited by local hydrogen permitting. Data was gathered to determine whether Steamers can meet or exceed pyrolytic torch performance. The RASIRC Steamer uses de-ionized water as its steam source, eliminating dependence on hydrogen and oxygen. A non-porous hydrophilic membrane selectively allows water vapor to pass. All other molecules are greatly restricted, so contaminants in water such as dissolved gases, ions, total organic compounds (TOC), particles, and metals can be removed in the steam phase. The MEMS manufacturer improved growth rate by 7% over the growth range from 1?m to 3.5?m. Over a four month period, wafer uniformity, refractive index, wafer stress, and etch rate were tracked with no significant difference found. The elimination of hydrogen generated a four-month return on investment (ROI). Mean time between failure (MTBF) was increased from 3 weeks to 32 weeks based on three Steamers operating over eight months.

Spiegelman, Jeffrey J.

2010-02-01

243

Cobalt silicon mixed oxide nanocomposites by modified sol gel method  

NASA Astrophysics Data System (ADS)

Cobalt silicon mixed oxide materials (Co/Si=0.111, 0.250 and 0.428) were synthesised starting from Co(NO3)26H2O and Si(OC2H5)4 using a modified sol gel method. Structural, textural and surface chemical properties were investigated by thermogravimetric/differential thermal analyses (TG/DTA), XRD, UV vis, FT-IR spectroscopy and N2 adsorption at -196 C. The nature of cobalt species and their interactions with the siloxane matrix were strongly depending on both the cobalt loading and the heat treatment. All dried gels were amorphous and contained Co2+ ions forming both tetrahedral and octahedral complexes with the siloxane matrix. After treatment at 400 C, the sample with lowest Co content appeared amorphous and contained only Co2+ tetrahedral complexes, while at higher cobalt loading Co3O4 was present as the only crystalline phase, besides Co2+ ions strongly interacting with siloxane matrix. At 850 C, in all samples crystalline Co2SiO4 was formed and was the only crystallising phase for the nanocomposite with the lowest cobalt content. All materials retained high surface areas also after treatments at 600 C and exhibited surface Lewis acidity, due to cationic sites. The presence of cobalt affected the textural properties of the siloxane matrix decreasing microporosity and increasing mesoporosity.

Esposito, Serena; Turco, Maria; Ramis, Gianguido; Bagnasco, Giovanni; Pernice, Pasquale; Pagliuca, Concetta; Bevilacqua, Maria; Aronne, Antonio

2007-12-01

244

Silicon oxide permeation barrier coating of PET bottles and foils  

NASA Astrophysics Data System (ADS)

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.

Steves, Simon; Deilmann, Michael; Awakowicz, Peter

2009-10-01

245

Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition  

SciTech Connect

We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiO{sub x}, 0oxidation. The SiO{sub x} films were deposited by plasma-enhanced chemical vapor deposition at different nitrous-oxide/silane flow ratios. The physical and optical properties of the SiO{sub x} films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 deg. C, the intermediate Si continuum in XPS spectra (referring to the suboxide) split to Si peaks corresponding to SiO{sub 2} and elemental Si. This change indicates the phase separation of the SiO{sub x} into more stable SiO{sub 2} and Si clusters. Raman, high-resolution transmission electron microscopy and optical absorption confirmed the phase separation and the formation of Si NCs in the films. The size of Si NCs increases with increasing Si concentration in the films and increasing annealing temperature. Two photoluminescence (PL) bands were observed in the films after annealing. The ultraviolet (UV)-range PL with a peak fixed at 370-380 nm is independent of Si concentration and annealing temperature, which is a characteristic of defect states. Strong PL in red range shows redshifts from {approx}600 to 900 nm with increasing Si concentration and annealing temperature, which supports the quantum confinement model. After oxidation of the high-temperature annealed films, the UV PL was almost quenched while the red PL shows continuous blueshifts with increasing oxidation time. The different oxidation behaviors further relate the UV PL to the defect states and the red PL to the recombination of quantum-confined excitions.

Chen, X.Y.; Lu, Y.F.; Tang, L.J.; Wu, Y.H.; Cho, B.J.; Xu, X.J.; Dong, J.R.; Song, W.D. [Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore); Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511 (United States); Institute of Microelectronics, 11 Science Park Road, Singapore 117685 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore); Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore); Data Storage Institute, 5 Engineering Drive 1, Singapore 117608 (Singapore)

2005-01-01

246

The modulation on luminescence of Er3+-doped silicon-rich oxide films by the structure evolution of silicon nanoclusters.  

PubMed

A series of silicon-rich oxide (SRO) and erbium-doped SRO (SROEr) films imbedded with structural tunable silicon nanoclusters (Si NCs) have been fabricated using sputtering followed by post-annealing. The coalescence of Si NCs is found in the films with large Si excess. The energy transfer rate between Si NCs and Er3+ is enhanced, but the luminescence efficiencies of both Si NCs and Er3+ are reduced by the coalescent microstructures. Optimization of the microstructures of Si NCs is performed, and the preferential optical performance for both Si NCs and Er3+ could be achieved when Si NCs were separated in microstructures. PMID:23331713

Jin, Lu; Li, Dongsheng; Xiang, Luelue; Wang, Feng; Yang, Deren; Que, Duanlin

2013-01-18

247

The modulation on luminescence of Er3+-doped silicon-rich oxide films by the structure evolution of silicon nanoclusters  

PubMed Central

A series of silicon-rich oxide (SRO) and erbium-doped SRO (SROEr) films imbedded with structural tunable silicon nanoclusters (Si NCs) have been fabricated using sputtering followed by post-annealing. The coalescence of Si NCs is found in the films with large Si excess. The energy transfer rate between Si NCs and Er3+ is enhanced, but the luminescence efficiencies of both Si NCs and Er3+ are reduced by the coalescent microstructures. Optimization of the microstructures of Si NCs is performed, and the preferential optical performance for both Si NCs and Er3+ could be achieved when Si NCs were separated in microstructures.

2013-01-01

248

In situ transmission infrared spectroscopy of high-kappa oxide atomic layer deposition onto silicon surfaces  

NASA Astrophysics Data System (ADS)

Ultra-thin aluminum oxide (Al2O3) and hafnium oxide (HfO2) layers have been grown by atomic layer deposition (ALD) using tri-methyl-aluminum (TMA) and tetrakis-ethyl-methyl-amino-hafnium (TEMAH) respectively with heavy water (D2O) as the oxidizing agent. Several different silicon surfaces were used as substrates such as hydrogen terminated silicon (H/Si), SC2 (or RCA 2) cleaned native silicon oxide (SiO 2/Si), and silicon (oxy)nitride. In-situ transmission Fourier transform infrared spectroscopy (FTIR) has been adopted for the study of the growth mechanisms during ALD of these films. The vibrational spectra of gas phase TEMAH and its reaction byproducts with oxidants have also been investigated. Density functional theory (DFT) normal mode calculations show a good agreement with the experimental data when it is combined with linear wave-number scaling method and Fermi resonance mechanism. Ether (-C-O-C-) and tertiary alkylamine (N(R1R 2R3)) compounds are the two most dominant products of TEMAH reacting with oxygen gas and water. When ozone is used as the oxidant, gas phase CH2O, CH3NO2, CH3-N=C=O and other compounds containing -(C=O)- and --C-O-C- (or --O-C-) segments are observed. With substrate temperatures less than 400C and 300C for TMA and TEMAH respectively, Al oxide and Hf oxide ALD can be appropriately performed on silicon surfaces. Thin silicon (oxy)nitride thermally grown in ammonia on silicon substrate can significantly reduce silicon oxide interlayer formation during ALD and post-deposition annealing. The crystallization temperature of amorphous ALD grown HfO2 on nitridized silicon is 600C, which is 100C higher than on the other silicon surfaces. When HfO2 is grown on H/Si(111) at 100C deposition temperature, minimum 5--10 ALD cycles are required for the full surface coverage. The steric effect can be seen by the evolution of the H-Si stretching mode at 2083 cm-1. The observed red shift of H-Si stretching to 2060 cm-1 can be caused by Si-H...Hf interactions or by the dielectric screening effect of as-grown high-kappa moiety. A summary of local bonding models with vibrational mode assignments of the adsorbed TMA and TEMAH on silicon surfaces is presented based on the analysis of the substructure of silicate interfacial band at 900--1100 cm-1.

Ho, Ming-Tsung

249

Hydrothermal synthesis of sodium bismuth titanate and titanate nanofibers  

Microsoft Academic Search

A hydrothermal processing method was developed for the synthesis of sodium bismuth titanate powders and thin films from suitable precursors at 150C. Oxide precursors were best suited for preparing pure phase materials. The sodium bismuth titanate powders consisted of cube shaped crystals. A modified solution-reprecitation model involving partial dissolution of the precursors was proposed to explain the growth of these

Animesh Kundu

2008-01-01

250

Reaction of Hydrogen Fluoride Gas at High Temperatures with Silicon Oxide Film and Silicon Surface  

NASA Astrophysics Data System (ADS)

The chemical nature of hydrogen fluoride gas at high temperatures, 523 1173 K, for etching silicon dioxide in hydrogen ambient at atmospheric pressure is studied, for the first time. Although only a slight decrease in the silicon dioxide film thickness can be observed below 1000 K, its surface is significantly etched above 1000 K. Hydrogen fluoride gas in the temperature range of 500-1000 K in hydrogen ambient is experimentally shown to be nonreactive with silicon dioxide. The existence of water molecules is necessary for hydrogen fluoride gas to etch silicon dioxide even at high temperatures.At temperatures above 873 K, hydrogen fluoride gas can react to roughen the surface of the silicon substrate. The corrosion of silicon carbide by hydrogen fluoride gas is also observed as the formation of pits at the surface.

Habuka, Hitoshi; Otsuka, Toru

1998-11-01

251

Effect of yttrium on the oxide scale adherence of pre-oxidized silicon-containing heat-resistant alloy  

Microsoft Academic Search

This paper investigates the effect of the rare earth element yttrium on the rupture behaviour of the oxide scale on the silicon-containing heat-resistant alloy during cooling. After 10h of oxidation, yttrium is found to facilitate the formation of internal oxides (silica) at the scalematrix interface. Due to the twinning observed by scanning transmission electron microscopy (STEM) in silica, the critical

Jingbo Yan; Yimin Gao; Yudi Shen; Fang Yang; Dawei Yi; Zhaozhong Ye; Long Liang; Yingqian Du

2011-01-01

252

Intense green-yellow electroluminescence from Tb+-implanted silicon-rich silicon nitride/oxide light emitting devices  

NASA Astrophysics Data System (ADS)

High optical power density of 0.5 mW/cm2, external quantum efficiency of 0.1%, and population inversion of 7% are reported from Tb+-implanted silicon-rich silicon nitride/oxide light emitting devices. Electrical and electroluminescence mechanisms in these devices were investigated. The excitation cross section for the 543 nm Tb3+ emission was estimated under electrical pumping, resulting in a value of 8.2 10-14 cm2, which is one order of magnitude larger than one reported for Tb3+:SiO2 light emitting devices. These results demonstrate the potentiality of Tb+-implanted silicon nitride material for the development of integrated light sources compatible with Si technology.

Berencn, Y.; Wutzler, R.; Rebohle, L.; Hiller, D.; Ramrez, J. M.; Rodrguez, J. A.; Skorupa, W.; Garrido, B.

2013-09-01

253

Clockwise C-V hysteresis phenomena of metal--tantalum-oxide--silicon-oxide--silicon ( p) capacitors due to leakage current through tantalum oxide  

SciTech Connect

Thermal tantalum oxide with a thickness of 620 A was studied. The dc leakage resistance and high-frequency (1-MHz) resistance of a metal--tantalum-oxide--silicon capacitor were found to be on the order of 10/sup 8/ and 1 ..cap omega.. cm/sup 2/, respectively. The C-V behavior of the capacitor, with its initial states being carefully treated, was reproduced and observed to be dependent on the return voltage and hold time (at return point) of the measurement conditions. And only negative charges were observed to be responsible for the conduction current through tantalum oxide. A model with the considerations of the ac equivalent circuit and low-frequency leakage characteristic of tantalum oxide was proposed for these observations. Theoretical examples, with their parameters being suitably given according to the measured data, were shown, and they explained the experimental observations quite well. It is found that the measurement conditions and effect of the ac resistance of tantalum oxide on the determination of flat-band capacitance are important and should be carefully considered when one is interpreting the interface charges from C-V curves.

Hwu, J.; Jeng, M.; Wang, W.; Tu, Y.

1987-11-15

254

Dimethyl sulfoxide as a mild oxidizing agent for porous silicon and its effect on photoluminescence  

SciTech Connect

Dimethyl sulfoxide acts as a mild room-temperature oxidant of luminescent porous silicon. The oxidation reaction is accompanied by a loss in photoluminescence intensity from the silicon nanocrystallites, indicating that the oxide formed under these conditions is electronically defective. The rate of oxidation is reduced if the reaction is carried out in the presence of the radical traps 2,6-di-tert-butyl-4-methylphenol (butylated hydroxytoluene, BHT) or cumene. In addition, photoluminescence intensity is preserved if the DMSO oxidation reaction is carried out in the presence of high concentrations of BHT. The BHT is proposed to form a more electronically passive oxide layer by hydrogenating the surface radicals (dangling bonds) generated during the oxidation reaction.

Song, J.H.; Sailor, M.J. [Univ. of California, San Diego, CA (United States). Dept. of Chemistry and Biochemistry

1998-06-29

255

RF Reactive Magnetron Sputter Deposition of Silicon Sub-Oxides  

NASA Astrophysics Data System (ADS)

RF reactive magnetron plasma sputter deposition of silicon sub oxide E.D. van Hattum Department of Physics and Astronomy, Faculty of Sciences, Utrecht University The work described in the thesis has been inspired and stimulated by the use of SiOx layers in the direct inductive printing technology, where the SiOx layer is used as the charge retention layer on the drums for copying and printing devices. The thesis describes investigations of the plasma and of processes taking place on the sputter target and on the SiOx growth surface in the room temperature, RF reactive magnetron plasma sputter deposition technology. The sputtering target consists of silicon and the reactive atmosphere consists of an Ar/O2 mixture. The composition of the grown SiOx layers has been varied between x=0 and x=2 by variation of the O2 partial pressure. The characteristics of the growth process have been related to the nanostructural properties of the grown films. The deposition system enables the characterisation of the plasma (Langmuir probe, energy resolved mass spectrometer) and of the growing film (Elastic Recoil Detection (ERD), Fourier transform infrared absorption spectroscopy) and is connected to a beamline of a 6MV tandem van de Graaff accelerator. Also Rutherford Backscattering Spectrometry and X-ray Photoelectron Spectroscopy have been applied. It is shown how ERD can be used as a real-time in-situ technique. The thesis presents spatially resolved values of the ion density, electron temperature and the quasi-electrostatic potential, determined using a Langmuir probe. The plasma potential has a maximum about 2 cm from the cathode erosion area, and decreases (more than 200 V typically) towards the floating sputter cathode. The potential decreases slightly in the direction towards the grounded growth surface and the positive, mainly Ar+, ions created in the large volume of the plasma closest to the substrate are accelerated towards the growth surface. These ions obtain a few eV of kinetic energy in the plasma and around 30-50 eV in the anode sheath, and bombard the growing film. Some of them are incorporated in the grown material. The flux of ions on the growth surface hardly depends on the power injected into the plasma. Since the growth rate increases strongly with increasing injected power, at the same time the relative ion bombardment (about 10-20 ions per deposited atom) decreases strongly. The hypothesis that the microstructure of the grown material depends on the ion bombardment is not supported by the results, as deduced from the infrared analysis. The oxygen, incorporated in the growing SiOx, originates for ~65 % from O2 and for about 30 % from atomic oxygen produced in the plasma. A minority contribution is from SiO sputtered from the cathode. The oxygen coverage in the sputter erosion area appears low for all oxygen partial pressures leading to x<2. This explains why the silicon growth rate does not depend on the O2 partial pressure in the range where x < 2 is grown. It is discussed how this observation relates to the details of the rf plasma deposition setup.

van Hattum, E. D.

2007-01-01

256

Parallel-local anodic oxidation of silicon surfaces by soft stamps  

NASA Astrophysics Data System (ADS)

We investigate the fabrication of nanometric patterns on silicon surfaces by using the parallel-local anodic oxidation technique with soft stamps. This method yields silicon oxide nanostructures 15 nm high, namely at least five times higher than the nanostructures made with local anodic oxidation using atomic force microscopy, and thanks to the size of the stamp enables one to pattern the surface across a centimetre length scale. To implement this technique, we built a machine to bring the metallized polydimethylsiloxane stamp in contact with the silicon surface, subsequently inserted in a sealed chamber with controlled relative humidity. The oxide nanostructures are fabricated when a bias voltage of 36 V is applied between the stamp and the silicon for 2 min, with a relative humidity of 90%. The flexibility of the stamp enables a homogeneous conformal contact with the silicon surface, resulting in an excellent reproducibility of the process. Moreover, by means of two subsequent oxidations with the same stamp and just rotating the sample, we are able to fabricate complex nanostructures. Finally, a detailed study of the oxidation mechanism, also using a finite element analysis, has been performed to understand the underlying mechanism.

Albonetti, Cristiano; Martinez, Javier; Losilla, Nuria S.; Greco, Pierpaolo; Cavallini, Massimiliano; Borgatti, Francesco; Montecchi, Monica; Pasquali, Luca; Garcia, Ricardo; Biscarini, Fabio

2008-10-01

257

Photoconductivity characterization of silicon wafer mirror-polishing subsurface damage related to gate oxide integrity  

Microsoft Academic Search

The correlation between gate oxide integrity, photoconductivity amplitude and surface microroughness was systematically measured with 9 SC1 cleanings to remove residual subsurface damage induced by mirror polishing on the subsurface of silicon wafers. The same measurements were also carried out for as-epitaxial wafers as a comparison. Measured gate oxide integrity and photoconductivity amplitude in polished wafers increased with increase in

Y. Ogita; K Kobayashi; H Daio

2000-01-01

258

Evidence that blue luminescence of oxidized porous silicon originates from SiO2  

Microsoft Academic Search

We have analyzed red and blue luminescence from porous silicon as a function of oxidation parameters and feature dimension determined with an atomic force microscope. We have found correlation between blue luminescence intensity and the increase in feature size caused by oxidation. We have further shown that blue luminescence, is identical, with respect to spectrum and fast decay, to that

A. J. Kontkiewicz; A. M. Kontkiewicz; J. Siejka; S. Sen; G. Nowak; A. M. Hoff; P. Sakthivel; K. Ahmed; P. Mukherjee; S. Witanachchi; J. Lagowski

1994-01-01

259

Oscillatory kinetics of anodic oxidation of silicon influence of the crystallographic orientation  

Microsoft Academic Search

This work describes the oscillatory kinetics of the anodic oxide growth on silicon with crystallographic orientations (111) and (100). Although the oscillations are observed for two orientations if the experimental variables are properly chosen, their shape, amplitude and period are essentially different. It is shown that the oscillations are caused by a continuous growth of thin oxide layers at the

V Parkhutik; F. Costa Gmez; L. Moya Tarazona; R. Fenollosa Esteve

2000-01-01

260

X-ray reflectivity study of formation of multilayer porous anodic oxides of silicon.  

National Technical Information Service (NTIS)

The paper reports data on the kinetics of anodic oxide films growth on silicon in aqueous solutions of phosphoric acids as well as a study of the morphology of the oxides grown in a special regime of the oscillating anodic potential. X-ray reflectivity me...

Y. Chu R. Fenollosa V. Parkhutik H. You

1999-01-01

261

Impact of dose and energy of argon ( 40Ar +) and fluorine ( 19F +) ion implantation on uniformity of silicon oxidation  

Microsoft Academic Search

Oxidation rate of silicon was altered by implanting argon (40Ar+) and fluorine (19F+) ions at doses ranging from 51013 to 11016ions\\/cm2 and energies ranging from 20 to 70keV. Silicon wafers were oxidized using a rapid thermal oxidation system to retain post-implant conditions of the wafers until onset of oxidation cycle. Dramatic change in the uniformity of grown oxide was observed

Raj Kumar; M. S. Yadav; Kamal Kishore; Kumar Sambhawam; Sachin Goyal; D. N. Singh; P. J. George

2006-01-01

262

Bismuth-doped germanosilicate fibre laser with 20-W output power at 1460 nm  

SciTech Connect

We report the first cw bismuth - germanium codoped silica fibre laser with an output power above 20 W at 1460 nm and 50% optical efficiency. The laser operates on a transition between energy levels of bismuth-related active centres associated with silicon. The incorporation of a small amount ({approx}5 mol %) of germanium into the core of bismuth-doped silica fibre has little effect on its luminescence spectrum but reduces optical losses, which limit the laser efficiency. (letters)

Firstov, Sergei V; Shubin, Aleksei V; Khopin, V F; Mel'kumov, Mikhail A; Bufetov, Igor' A; Medvedkov, O I; Gur'yanov, Aleksei N; Dianov, Evgenii M

2011-07-31

263

The chemical composition changes of silicon and phosphorus in the process of native oxide formation of heavily phosphorus doped silicon  

Microsoft Academic Search

The chemical composition changes of silicon and phosphorus in the process of native oxide formation of both heavily phosphorus-doped Si(100) and polycrystalline Si prepared by HF-treatment were monitored for a period of 1 year, using angle dependent X-ray photoelectron spectroscopy (XPS). Right after HF-treatment, significant amounts of unoxidized-P (P?) and a new chemical state of Si (Si?) having an unstable

W. B Ying; Y Mizokawa; Y Kamiura; K Kawamoto; W. Y Yang

2001-01-01

264

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

PubMed

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

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

2013-05-13

265

Annealing behavior of atomic layer deposited hafnium oxide on silicon: Changes at the interface  

NASA Astrophysics Data System (ADS)

Thin films of hafnium oxide are deposited on Si(100) substrates by means of atomic layer deposition using tetrakis(diethylamino)hafnium and water on Si(100) at 300 C. Detailed studies of temperature induced annealing effects on the HfO2/Si interface are done using angle resolved x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and time of flight secondary ion mass spectroscopy (ToF-SIMS). As-deposited films show mostly native silicon oxide at the interface. Crystallization of HfO2 film initiates at about 600 C. As the annealing temperature is increased, the hafnium silicate content in the film is found to increase and the mostly silicon oxide interlayer is found to grow thicker under Ar atmosphere. Also, the formation of hafnium silicide is found to take place at temperatures >=800 C. The XPS data shows decomposition of the interfacial hafnium silicate layer into hafnium oxide and silicon oxide at 1000 C along with increasing formation of hafnium silicide. The ToF-SIMS data suggest interdiffusion of the hafnium oxide film and the interfacial silicon oxide during the annealing process.

Deshpande, Anand; Inman, Ronald; Jursich, Gregory; Takoudis, Christos G.

2006-05-01

266

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

PubMed

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

Baumgrtel, Thomas; von Borczyskowski, Christian; Graaf, Harald

2013-03-25

267

Preparation of highly aligned silicon oxide nanowires with stable intensive photoluminescence  

NASA Astrophysics Data System (ADS)

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.

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

2010-02-01

268

Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes  

PubMed Central

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.

von Borczyskowski, Christian; Graaf, Harald

2013-01-01

269

Selective Etching of Silicon Native Oxide with Remote-Plasma-Excited Anhydrous Hydrogen Fluoride  

Microsoft Academic Search

We demonstrate to the acceleration of the moistureless etching reaction between the silicon native oxide and the anhydrous hydrogen fluoride (AHF) gas, using remote-plasma-excited Ar gas at room temperature. The etching reaction is significantly enhanced by the remote-plasma-excitation for both the chemically grown native oxide films and the dehydrated oxide films. Then, we attempt to improve the selectivity of the

Yutaka Nakazawa; Yoji Saito

1998-01-01

270

X-Ray Reflectivity Study of Formation of Multilayer Porous Anodic Oxides of Silicon  

Microsoft Academic Search

Present work reports a study of the morphology of thin (50600 ) porous oxides of silicon grown in a special regime of the oscillating anodic potential. X-ray reflectivity (in-situ and ex-situ) was applied to analyze the morphology of oxides. It has been established that there is a direct correlation between a number of oscillations of potential during the oxide growth

Vitali Parkhutik; Y. Chu; H. You; Z. Nagy; P. A. Montano

2000-01-01

271

Buried-oxide silicon-on-insulator structures. I - Optical waveguide characteristics  

Microsoft Academic Search

Buried-oxide silicon-on-insulator structures are analyzed using both a multilayer transfer matrix approach and a simple approximate method. Results show that these structures can support low-loss leaky modes with substrate leakage losses under 1 dB\\/cm. Even for a reasonably thick silicon film layer, adjacent modes of the same polarization can have loss discriminations as large as 100 dB\\/cm. Mode effective indexes

Robert M. Emmons; Bulent N. Kurdi; Dennis G. Hall

1992-01-01

272

Research on silicon microchannel array oxidation insulation technology and stress issues  

NASA Astrophysics Data System (ADS)

Microchannel plate is widely used in the field of low light level night vision, photomultiplier, tubes, X-ray enhancer and so on. In order to meet the requirement of microchannel plate electron multiplier, we used the method of thermal oxidation to produce a thin film of silicon dioxide which could play a role in electric insulation. Silicon dioxide film has a high breakdown voltage, it can satisfy the high breakdown voltage requirements of electron multiplier. We should find the reasonable parameter values and preparation process in the oxidation so that the thickness and uniformity of the silicon dioxide layer would meet requirement. This article has been focused on researching and analyzing of the problem of oxide insulation and thermal stress in the process of production of silicon dioxide film. In this experiment, dry oxygen and wet oxygen were carried out respectively for 8 hours. The thickness of dry oxygen silicon dioxide films was 458 nm and wet oxygen silicon dioxide films was 1.4 ?m. Under these conditions, the silicon microchannel is uniformity and neat, meanwhile the insulating layer's breakdown voltage was measured at 450 V after the wet oxygen oxidation. By using ANSYS finite element software, we analyze the thermal stress, which came from the microchannel oxygen processes, under the conditions of which ambient temperature was 27 ? and porosity was 64%, we simulated the thermal stress in the temperature of 1200 ? and 1000 ?, finally we got the maximum equivalent thermal stress of 472 MPa and 403 MPa respectively. The higher thermal stress area was spread over Si-SiO2 interface, by simulate conditions 50% porosity silicon microchannel sample was selected for simulation analysis at 1100 ?, we got the maximum equivalent thermal stress of 472 MPa, Thermal stress is the minimum value of 410 MPa.

Chai, Jin; Li, Mo; Liang, Yong-zhao; Yang, Ji-kai; Wang, Guo-zheng; Duanmu, Qing-duo

2013-08-01

273

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

Microsoft Academic Search

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

Jinman Yang

2002-01-01

274

Dry Cleaning Technology for Removal of Silicon Native Oxide Employing Hot NH3\\/NF3 Exposure  

Microsoft Academic Search

A new dry cleaning technology for removal of silicon (Si) native oxides from contact holes employing a hot ammonium (NH3)\\/nitrogen trifluoride (NF3) mixture has been studied. The NH3\\/NF3 mixture heated at a high temperature in a quartz tube enabled etching of the silicon dioxide (SiO2) film placed in the downstream region. The mechanism of the etching reaction which was investigated

Hiroki Ogawa; Tomoharu Arai; Michihiko Yanagisawa; Takanori Ichiki; Yasuhiro Horiike

2002-01-01

275

Effects of electric fields and oxygen ion beams on silicon oxidation kinetics  

Microsoft Academic Search

Results of an experimental investigation into the effects of electric fields and oxygen ion beams on silicon oxidation between 25°C and 950°C are presented. A beam of positive or negative oxygen ions, generated in a point-to-plane corona discharge, is directed to the front surface of a silicon wafer. The back surface, which is grounded, manifests the effects of electric fields

Modlin

1983-01-01

276

Hot-pressing behaviour of silicon carbide powders with additions of aluminium oxide  

Microsoft Academic Search

The hot-pressing behaviour of different silicon carbide powders (average particle sizes ranging from ~ 0.5 to 9 m) with aluminium oxide additions ranging from 0.01 to 0.15 volume fractions was investigated. Using powders with an average particle size -2 for volume fractions of AI2O3\\u000a$$\\\\bar > $$\\u000a 0.02. A liquid phase forms at high temperatures which dissolves the silicon carbide

F. F. Lange

1975-01-01

277

Bismuth-doped tin oxide-coated carbon nanotube network: improved anode stability and efficiency for flow-through organic electrooxidation.  

PubMed

In this study, a binder-free, porous, and conductive 3D carbon-nanotube (CNT) network uniformly coated with bismuth-doped tin oxide (BTO) nanoparticles was prepared via a simple electrosorption-hydrothermal method and utilized for the electrooxidative filtration of organics. The BTO-CNT nanocomposite was characterized by scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, linear sweep voltammetry, and Tafel analysis. The submonolayer BTO coating is composed of 3.9 1.5 nm diameter nanoparticles (NPs). The oxygen-evolution potential of the BTO-CNT nanocomposite was determined to be 1.71 V (vs Ag/AgCl), which is 440 mV higher than an uncoated CNT anode. Anodic stability, characterized by CNT oxidative corrosion to form dissolved species, indicated that the BTO-CNT incurred negligible corrosion up to Vanode = 2.2 V, whereas the uncoated CNT was compromised at Vanode ? 1.4 V. The effect of metal oxide-nanoparticle coating on anodic performance was initially studied by oxalate oxidation followed by total organic carbon (TOC) and chemical oxygen demand (COD) analysis. The BTO-CNT displayed the best performance, with ?98% oxalate oxidation (1.2 s filter residence time) and current efficiencies in the range of 32 to >99%. The BTO-CNT anode energy consumption was 25.7 kW h kgCOD(-1) at ?93% TOC removal and 8.6 kW h kgCOD(-1) at ?50% TOC removal, comparable to state-of-the-art oxalate oxidation processes (22.5-81.7 kW h kgCOD(-1)). The improved reactivity, current efficiency, and energy consumption are attributed to the increased conductivity, oxygen-evolution potential, and stability of the BTO-CNT anode. The effectiveness and efficiency of the BTO-CNT anode as compared to the uncoated CNT was further investigated by the electrooxidative filtration of ethanol, methanol, formaldehyde, and formate, and it was determined to have TOC removals 2 to 8 times greater, mineralization current efficiencies 1.5 to 3.5 times greater, and energy consumption 4 to 5 times less than the uncoated CNT anode. Electrooxidation and anode passivation mechanisms are discussed. PMID:24040859

Liu, Han; Vajpayee, Akshay; Vecitis, Chad D

2013-10-01

278

Analysis of flicker noise for improved data retention characteristics in silicon-oxide-high-k-oxide-silicon flash memory using N2 implantation.  

PubMed

In this paper, we fabricate planar-type Silicon-Oxide-High-k-Oxide-Silicon (SOHOS) and the planar-type SOHOS devices with N2 implantation of 3 x 10(15) dose in a tunneling oxide to determine the impact of N2 implantation in the tunneling oxide of a memory device. The N2 implantation device has better retention characteristics than the device with no implantation. In order establish the correlation between N2 implantation and retention characteristic improvement, the low frequency noise (1/f noise) characteristic is investigated. The normalized drain current noise (S(ID)/I(D)2) level of the N2 implantation device is higher than that of the device with no implantation, which means that N2 implantation causes more trap formation near the interface. Considering that N2 implantation does not affect the DC transfer characteristics, such as mobility and sub-threshold slope, this finding indicates that the increase in the 1/f noise level is due to oxide traps rather than to interface traps. Therefore, the retention characteristic improvement in the N2 implantation device can be explained by the generation of higher number of oxide traps and an increase in the potential barrier blocking the leakage path in the tunneling oxide. PMID:23858853

Yang, S D; Jeong, K S; Yun, H J; Kim, Y M; Lee, S Y; Oh, J S; Lee, H D; Lee, G W

2013-05-01

279

Effects of oxidation and creep damage mechanisms on creep behavior in HIPed silicon nitrides  

SciTech Connect

The creep resistance of hot-isostatically pressed (HIPed) silicon nitride materials is ultimately dictated by its susceptibility to creep enhanced damage (e.g. cavitation) and oxidation induced damage. The evolution of these simultaneously occurring events has been examined in several HIPed silicon nitrides which were tested in tension at elevated temperatures. The activity and extent of each have found to be functions of several variables. These parameters and their roles are discussed and include the following: initial {alpha}/{beta} ratio of silicon nitride grains, reaction of stable/unstable phases in the as-received material, percentage and type of sintering aid, and grain boundary crystallinity, impurity content, and viscosity.

Wereszczak, A.A.; Ferber, M.K.; Kirkland, T.P.

1994-02-01

280

Degradation studies of ultrathin silicon oxide under electrical stress using a scanning tunneling microscope  

NASA Astrophysics Data System (ADS)

The ability of thin silicon oxides to remain stable under electrical stress is critical in today's microelectronics industry. Silicon oxides less than 10 nm thick play an important role in field effect transistors, dynamic random access memories and flash memories in which they are subject to fields in excess of 1 MV/cm. Operation under even more severe stress will be required in the future as device dimensions are reduced. We subject ultrathin silicon oxide, a few atomic layers at most, to electrical stress and observe the damage with a scanning tunneling microscope (STM). With the aid of a model to map the electric field in our system we identify two mechanisms which lead to permanent oxide degradation. One, causing severe damage, is initiated when the oxide field surpasses a threshold, which we determine. The other is less severe and is caused by bombardment from field emitted electrons. We find that this technique complements standard stress tests that use the planar metal-oxide-semiconductor capacitor geometry in that it provides a surface map of the damaged oxide's conductance properties rather than simply a spatial average. We also present results on the use of these thin oxides as a surface on which to locally deposit material in a STM induced chemical vapor deposition process. We find that deposition is sensitive to surface conditions with regard to the damage described above.

Hetrick, James Michael

281

Effective passivation of the low resistivity silicon surface by a rapid thermal oxide/plasma silicon nitride stack  

SciTech Connect

A passivation scheme involving plasma silicon nitride (PECVD SiN) deposition on top of SiO{sub 2} grown by rapid thermal oxidation is developed to attain a low surface recombination velocity ({ital S}) of nearly 10 cm/s on the 1.25 {Omega}cm {ital p}-type (100) silicon surface. Such low {ital S} values are achieved by the stack structure even when the rapid thermal oxide (RTO) or PECVD SiN films {ital individually} yield poorer surface passivation. Critical to achieving low {ital S} by the RTO/PECVD SiN stack is the use of a short, moderate temperature anneal (in this study 730{degree}C for 30 seconds) after the stack formation. This thermal treatment is believed to enhance the release and delivery of atomic hydrogen from the SiN film to the Si{endash}SiO{sub 2} interface, thereby reducing the density of interface traps at the silicon surface. Compatibility with this post-deposition anneal makes the stack passivation scheme attractive for cost-effective solar cell production where a similar anneal is required to form screen-printed contacts. {copyright} {ital 1998 American Institute of Physics.}

Narasimha, S.; Rohatgi, A. [Department of Electrical and Computer Engineering, University Center of Excellence for Photovoltaics Research and Education, Georgia Institute of Technology, Atlanta, Georgia30332-0250 (United States)

1998-04-01

282

Highly reliable ultrathin silicon oxide film formation at low temperature by oxygen radical generated in high-density krypton plasma  

Microsoft Academic Search

This paper focuses attention on electrical properties of silicon oxide films grown by oxygen radical generated in Kr\\/O2 mixed high-density microwave-excited plasma at 400C. They represent high growth rate, low activation energy, high dielectric strength, high charge-to-breakdown, and low interface trap density and bulk charge enough to replace thermally grown silicon oxide

Katsuyuki Sekine; Yuji Saito; Masaki Hirayama; Tadahiro Ohmi

2001-01-01

283

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

Microsoft Academic Search

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

L. Mathivanan; A. K. Arof

2000-01-01

284

Corrosion of ODS steels in leadbismuth eutectic  

Microsoft Academic Search

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 leadbismuth eutectic cooled reactors and spallation sources. Corrosion tests on five different ODS alloys were performed in flowing liquid leadbismuth eutectic

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

2008-01-01

285

Solutions of Simultaneous Equations for Oxidation Enhanced and Retarded Diffusions and Oxidation Stacking Fault in Silicon  

NASA Astrophysics Data System (ADS)

Equations for oxidation enhanced and retarded diffusions (OED and ORD) and oxidation stacking faults (OSF) in silicon have been solved simultaneously, using experimental results at 1100C for 1.0 104--2.4 105 s. A simple relation between the concentrations of self-interstitials and vacancies was assumed in order to obtain the solutions. It is concluded that the product of the concentrations of the self-interstitials and vacancies, CICV, is nearly equal to the value for thermal equilibrium, CI0CV0, and that the fractional components of the interstitialcy mechanism for self-, Sb and P diffusions are smaller than 0.5, smaller than 0.5 and larger than 0.5, respectively. This shows that the growth of OSF is caused mainly by the undersaturation of a vacancy, and that the ORD of Sb and the OED of P occur. The time dependences of the supersaturation ratios of the self-interstitials and vacancies were also obtained.

Yoshida, Masayuki; Matsumoto, Satoru; Ishikawa, Yutaka

1986-07-01

286

Effects of silicon concentration in SOFC alloy interconnects on the formation of oxide scales in hydrocarbon fuels  

Microsoft Academic Search

Oxide scale formations on FeCr alloy interconnects were investigated in anode gas (mixtures of CH4 and H2O) atmospheres for solid oxide fuel cells. The silicon concentration in FeCr alloy changed the microstructures of oxide scales, elemental distribution and oxide scale growth rates. Oxide scale is composed of the following phases from surface to inner oxides: FeMn spinel, Cr2O3, oxide scale\\/alloy

Teruhisa Horita; Haruo Kishimoto; Katsuhiko Yamaji; Natsuko Sakai; Yueping Xiong; Manuel E. Brito; Harumi Yokokawa

2006-01-01

287

Optical waveguides in oxygen-implanted buried-oxide silicon-on-insulator structures  

SciTech Connect

There is continued interest in the use of silicon as a basic material for integrated optics. Compatibility with the technology used for the fabrication of silicon integrated circuits is clearly an important motivation. Several silicon-based integrated-optical systems-waveguide demultiplexers, spectrum analyzers, and others - have already been described in the literature. Newer applications such as the interconnection of electronic circuits and systems, many of which are fabricated in silicon, make the question of the potential role of silicon in integrated optics all the more interesting. The optical waveguide is perhaps the most fundamental component needed for any integrated-optical system. The waveguiding properties of the oxygen-implanted, buried-oxide, silicon-on-insulator structures currently being developed for use in microelectronics are analyzed. It was found that, in spite of the fact that the buried-oxide layer is only a few tenths of a micrometer thick, the single-crystal overlayer can support Te/sub O/ guided-wave propagation, at subbandgap wavelengths, with losses due to substrate radiation leakage at or below the benchmark level of 1 dB/cm.

Kurdi, B.N.; Hall, D.G.

1988-02-01

288

Ceramic bearing development. Silicon nitride bearing balls of improved reliability: Thermal oxidation. Final report, 1 January 1995-31 October 1996  

Microsoft Academic Search

The major objective of this work was to improve the reliability of silicon nitride bearing balls by means of an optimized thermal oxidation treatment. Previous work had shown that the thermal fracture resistance of silicon nitride bearing balls increased when the balls were heated and oxidized in air. An optimized oxidation treatment for NBD-200 silicon nitride balls was developed, using

Burk

1996-01-01

289

Oxidation of silicon nitride hot pressed with Y 2 O 3 +MgO  

Microsoft Academic Search

Oxidation tests of silicon nitride hot pressed with combined Y2O3 and MgO additions in the compatibility field Si3N4-Si2N2O-Y2Si2O7, performed at 1193 to 1658 K under 98 kPa air atmosphere for 30 h, result in parabolic oxidation kinetics and three different oxidation regimes. At T?H=120 kJ mol-1) oxygen diffusion is suggested to be the more probable limiting step for oxidation, whereas

G. N. Babini; A. Bellosi; P. Vincenzini

1983-01-01

290

Configurational statistical model for the damaged structure of silicon oxide after ion implantation  

NASA Astrophysics Data System (ADS)

A configurational model for silicon oxide damaged after a high-dose ion implantation of a nonreactive species is presented. Based on statistics of silicon-centered tetrahedra, the model takes into account not only the closest environment of a given silicon atom, but also the second neighborhood, so it is specified whether the oxygen attached to one given silicon is bridging two tetrahedra or not. The frequencies and intensities of infrared vibrational bands have been calculated by averaging over the distributions and these results are in agreement with the ones obtained from infrared experimental spectra. Likewise, the chemical shifts obtained from x-ray photoelectron spectroscopy (XPS) analysis are similar to the reported values for the charge-transfer model of SiOx compounds.

Garrido, B.; Samitier, J.; Morante, J. R.; Montserrat, J.; Domnguez, C.

1994-06-01

291

Mid-infrared optical properties of thin films of aluminum oxide, titanium dioxide, silicon dioxide, aluminum nitride, and silicon nitride.  

PubMed

The complex refractive index components, n and k, have been studied for thin films of several common dielectric materials with a low to medium refractive index as functions of wavelength and stoichiometry for mid-infrared (MIR) wavelengths within the range 1.54-14.29 ?m (700-6500 cm(-1)). The materials silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, and titanium oxide are prepared using room temperature reactive sputter deposition and are characterized using MIR variable angle spectroscopic ellipsometry. The investigation shows how sensitive the refractive index functions are to the O2 and N2 flow rates, and for which growth conditions the materials deposit homogeneously. It also allows conclusions to be drawn on the degree of amorphousness and roughness. To facilitate comparison of the materials deposited in this work with others, the index of refraction was also determined and provided for the near-IR and visible ranges of the spectrum. The results presented here should serve as a useful information base for designing optical coatings for the MIR part of the electromagnetic spectrum. The results are parameterized to allow them to be easily used for coating design. PMID:23033094

Kischkat, Jan; Peters, Sven; Gruska, Bernd; Semtsiv, Mykhaylo; Chashnikova, Mikaela; Klinkmller, Matthias; Fedosenko, Oliana; Machulik, Stephan; Aleksandrova, Anna; Monastyrskyi, Gregorii; Flores, Yuri; Masselink, W Ted

2012-10-01

292

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

PubMed Central

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.

2011-01-01

293

Judd-Ofelt analysis, frequency upconversion, and infrared photoluminescence of Ho3+-doped and Ho3+/Yb3+-codoped lead bismuth gallate oxide glasses  

NASA Astrophysics Data System (ADS)

Ho3+-doped and Ho3+/Yb3+-codoped lead bismuth gallate (PBG) oxide glasses were prepared and their spectroscopic properties were investigated. The derived Judd-Ofelt intensity parameters (?2=6.8110-20 cm2, ?4=2.3110-20 cm2, and ?6=0.6710-20 cm2) indicate a higher asymmetry and stronger covalent environment for Ho3+ sites in PBG glass compared with those in tellurite, fluoride (ZBLAN), and some other lead-contained glasses. Intense frequency upconversion emissions peaking at 547, 662, and 756 nm as well as infrared emissions at 1.20 and 2.05 ?m in Ho3+/Yb3+-codoped PBG glass were observed, confirming that energy transfer between Yb3+ and Ho3+ takes place, and a two-phonon-assisted energy transfer from Yb3+ to Ho3+ ions was determined by the calculation using phonon sideband theory. The 1.20 ?m emission observed was primarily due to the weak multiphonon deexcitation originated from the small phonon energy of PBG glass (~535 cm-1). A large product of emission cross-section and measured lifetime (9.9310-25 cm2 s) was obtained for the 1.20 ?m emission and the gain coefficient dependence on wavelength with population inversion rate (P) was performed. The peak emission cross-section for 2.05 ?m emission was calculated to be 4.7510-21 cm2. The relative mechanism of Ho3+-doped and Ho3+/Yb3+-codoped PBG glasses on their spectroscopic properties was also discussed. Our results suggest that Ho3+/Yb3+-doped PBG glasses are a good potential candidate for the frequency upconversion devices and infrared amplifiers/lasers.

Zhou, Bo; Pun, Edwin Yue-Bun; Lin, Hai; Yang, Dianlai; Huang, Lihui

2009-11-01

294

HRTEM Investigation of Silicon Nitride Powder Coated with Yttrium Oxide-Precursor  

Microsoft Academic Search

Ceramic matrix composites based on silicon nitride (Si3N4) are potential candidates for use as high-temperature structural materials. However, the high melting point and low self-diffusion coefficient of Si3N 4 makes fabrication difficult without the addition of a sintering aid such as yttrium oxide (Y203) or aluminium oxide (AI20 3). Addition of sintering aid through mechanical mixing does not produce homogeneous

I. J. Davies; B. Djuricic; S. Pickering; M. De Hosson

295

Influence of Fluorine on the Conductivity and Oxidation of Silicon Nanomembranes after Hydrofluoric Acid Treatment  

Microsoft Academic Search

After immersion in hydrofluoric acid, the sheet resistance of a 220-nm-thick silicon nanomembrane, measured in dry air by van der Pauw method, drops around two orders of magnitude initially, then increases and reaches the level of a sample with a native oxide surface in about one month. The surface component and oxidation rate are also characterized by x-ray photo electronic

Xiang-Fu Zhao; Ping Han; Rong Zhang; You-Dou Zheng

2011-01-01

296

Control factor of native oxide growth on silicon in air or in ultrapure water  

Microsoft Academic Search

Native silicon (Si) oxide growth on Si (100) wafers in air and in ultrapure water at room temperature requires coexistence of water and oxygen in the air and ultrapure water ambients. The growth rate data on n-, n+-, and p+-Si (100) in air indicate layer-by-layer growth of an oxide. The growth rate on n-Si (100) in ultrapure water may be

M. Morita; T. Ohmi; E. Hasegawa; M. Kawakami; K. Suma

1989-01-01

297

Mesoscopic Phenomena in Single Crystalline Bismuth Systems.  

National Technical Information Service (NTIS)

Contents: General Introduction; Material properties, band structure, and electrical transport properties of bismuth: theoretical background; Epitaxial growth of bismuth films and bismuth-antimony heterostructures; Resistance measurements on bismuth-antimo...

J. A. van Hulst

1995-01-01

298

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

NASA Astrophysics Data System (ADS)

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.

Dehoff, Ryan Richard

299

A high-density array of size-controlled silicon nanodots in a silicon oxide nanowire by electron-stimulated oxygen expulsion.  

PubMed

Methods of producing Si nanodots embedded in films of silicon oxide and silicon nitride abound, but fabrication of Si nanodots in a nanowire of these materials is very rare despite the fact that nanowire architecture enhances the charge collection and transport efficiencies for solar cells and field-effect transistors. We report a novel fabrication method for a high-density array of size-controlled sillicon nanodots from a silicon oxide nanowire using electron-beam irradiation. Our results demonstrate that a highly dense phase of Si nanodots with a narrow size distribution can be made from a silicon oxide nanowire with a core-shell structure of crystalline silicon-rich oxide (c-SRO)/amorphous silicon oxide (a-SiO(2)). This new nanomaterial shows the carrier transport characteristics of a semiconductor. The initially produced amorphous Si nanodots can be readily turned into crystalline Si (c-Si) nanodots by thermal annealing. Key characteristics of c-Si nanodots such as their size, number density, and rate of nucleation and growth are easily controlled by varying the electron radiation dose and annealing temperature. Nanodot formation is mechanistically initiated by electron trapping at the c-SRO core as well as at the core-shell interface, which leads to out-diffusion of the negatively charged oxygen through Coulomb repulsion, fostering the aggregation of Si atoms. PMID:19435375

Park, Gyeong-Su; Lee, Eun Kyung; Lee, Jun Ho; Park, Juyeon; Kim, Seong Keun; Li, Xiang Shu; Park, Ju Cheol; Chung, Jae Gwan; Jeon, Woo Sung; Heo, Sung; Lee, Jae Hak; Choi, Byoung Lyong; Kim, Jong Min

2009-05-01

300

Influence of silicon on growth process of plasma electrolytic oxidation coating on AlSi alloy  

Microsoft Academic Search

Ceramic coating was formed on the surface of AlSi alloy via plasma electrolytic oxidation (PEO) technique. The influence of silicon on the growth process, morphology and composition of the PEO coating was investigated. It was observed that the coating was simultaneously formed on the surface of primary ? phase and eutectic (?+?) in the initial stage of PEO process. No

J. He; Q. Z. Cai; H. H. Luo; L. Yu; B. K. Wei

2009-01-01

301

Advantage of Shallow Trench Isolation over Local Oxidation of Silicon on Alignment Tolerance  

Microsoft Academic Search

We investigate the differences between the breakdown characteristics against contact hole etching for shallow trench isolation (STI) and the local oxidation of silicon (LOCOS). Although the breakdown voltage of STI varied negligibly despite the large contact overlap, the isolation characteristics of the LOCOS were drastically degraded due to the slight overlapping with the contact hole. The cross-sectional scanning electron microscope

Katsuomi Shiozawa; Toshiyuki Oishi; Kohei Sugihara; Akihiko Furukawa; Yuji Abe; Yasunori Tokuda

1999-01-01

302

High-Resolution Electron-Microscopy Studies of Native Oxide on Silicon.  

National Technical Information Service (NTIS)

High-resolution electron microscopy (HREM) of cross-sectional specimens has shown that the thickness of the native oxide on silicon is 20 +- 3A, independent of surface orientation. This result has confirmed the value 21 +- 4A determined by ellipsometry as...

J. H. Mazur R. Gronsky J. Washburn

1983-01-01

303

Composition and structure of native oxide on silicon by high resolution analytical electron microscopy  

Microsoft Academic Search

Compositional analysis of thin nanoscale native oxide films formed on {l brace}001{r brace} silicon wafer surfaces at room temperature was done with an electron energy loss spectrometer coupled to an analytical electron microscope having a field emission source, with better than 4 nm spatial resolution. The electron energy loss spectra show a shift in the threshold onset energy of the

M. J. Kim; R. W. Carpenter

1990-01-01

304

Local etching of silicon using a solid mask from porous aluminum oxide  

SciTech Connect

Technological features of nanoprofiling of silicon protected by a solid mask made of porous aluminum oxide are considered. It is shown that the method based on bombarding structures with accelerated neutral atoms (in particular, argon atoms) is efficient for etching through this mask.

Belov, A. N. [Moscow State Institute of Electronic Engineering (Technical University) (Russian Federation)], E-mail: belov@dsd.miee.ru

2008-12-15

305

Silicon anodic oxides grown in the oscillatory anodisation regime kinetics of growth, composition and electrical properties  

Microsoft Academic Search

The work presents the results of studying the anodic oxide growth at silicon in a special regime when the values of the anodic current or potential are oscillating in time. The oscillatory kinetics is ranging from intermittent and damped oscillations to very regular and long-lasting ones. The critical experimental factors allowing to observe well-defined oscillations are the composition of electrolyte,

Vitali Parkhutik

2001-01-01

306

Nonideal behaviour of buried channel CCDs caused by oxide and bulk silicon traps  

Microsoft Academic Search

Analytical expressions are given for noise in FETs due to charge trapping at defects in the silicon and in the oxide. Conditions which lead to 1\\/f; and 1\\/f;2 spectra are described. A new physical model of the noise mechanisms in ideal depletion mode MOSFETS is fully described. Measurements on various MOSFETs in CCDs and other systems are compared with the

K. Kandiah; F. B. Whiting

1991-01-01

307

Optical properties of bismuth-doped silica fibres in the temperature range 300 - 1500 K  

SciTech Connect

The visible and near-IR absorption and luminescence bands of bismuth-doped silica and germanosilicate fibres have been measured for the first time as a function of temperature. The temperature-dependent IR luminescence lifetime of a bismuth-related active centre associated with silicon in the germanosilicate fibre has been determined. The Bi{sup 3+} profile across the silica fibre preform is shown to differ markedly from the distribution of IR-emitting bismuth centres associated with silicon. The present results strongly suggest that the IR-emitting bismuth centre comprises a lowvalence bismuth ion and an oxygen-deficient glass network defect. (optical fibres, lasers and amplifiers. properties and applications)

Dvoretskii, D A; Bufetov, Igor' A; Vel'miskin, V V; Zlenko, Alexander S; Khopin, V F; Semjonov, S L; Guryanov, Aleksei N; Denisov, L K; Dianov, Evgenii M

2012-09-30

308

Electron stimulated oxidation and rhenium electrical contacts on alpha-silicon carbide  

NASA Astrophysics Data System (ADS)

Electron stimulated oxidation (ESO) and rhenium (Re) metallizations on alpha-silicon carbide (6H-SiC) were studied. ESO was quantified versus electron beam exposure, total vacuum pressure, beam energy Ep (3 to 6 keV), and current Ip (25 to 500 nA), while monitoring chemical change using Auger electron spectroscopy (AES). Vacuum chamber pressures below 2.6 x 10 -8 Torr required beam irradiation to induce oxidation. A positive linear correlation between oxidation rate and total chamber pressure was observed. Rate did not correlate with concentration of a particular ambient species (H2O, CO, or CO2). Oxidation rate decreased with increased Ep suggesting surface secondary electrons stimulate oxidation. Dependence of oxidation rate on Ip indicated current limited dissociation below 200 nA. Rhenium contacts (1000 angstroms thick) were deposited on carbon-rich, stoichiometric, and silicon-rich 6H-SiC surfaces. Morphology (Dektak), texture (X-ray diffraction (XRD)), chemistry (AES), and electrical properties (current/voltage (I--V)) were characterized for as-deposited and annealed (120 minute, 1000C, <1 x 10-6 Torr) contacts. As-deposited films were non-ohmic with total contact resistances of 59, 1620 and 110 ohms for carbon-rich, stoichiometric, and silicon-rich surfaces, respectively. Films grown on carbon-rich surfaces were non-specular, granular, and often delaminated during characterization. Island-growth was observed on stoichiometric surfaces with thickness variations of 800 angstroms. Films remained specular for 3 hours, but then became hazy from oxidation. Textured (101) growth was observed on silicon-rich surfaces. Thickness varied by 250 angstroms and films resisted ex-situ oxidation for more than 24 hours. Annealed samples remained specular without visual signs of oxidation. Films were smoothed with thickness variance less than 100 angstroms. Phase separation was observed based on formation of interfacial Re clusters and 100 angstrom graphite surface layers. Auger confirmed as-deposited Si layers (50 to 100 angstroms) were consumed by reaction during annealing and Re/Si and Si/SiC interfaces were diffused 500 angstroms more compared to as-deposited interfaces. Annealed contacts were largely ohmic with averaged total contact resistances reduced to 11,3.2, and 1.4O for carbon-rich, stoichiometric, and silicon-rich samples, respectively. Average specific contact resistances of 7.0 x 10-5 Ocm2 for stoichiometric and 1.6 x 10-5 Ocm2 for silicon-rich samples were observed.

McDaniel, Gavin Young

309

Half-Metallicity in Europium Oxide Conductively Matched with Silicon  

SciTech Connect

EuO1-x--a remarkably versatile ferromagnetic semiconductor with variable transport properties--incorporated into a heterostructure with n+ doped silicon is shown to be {approx}90% spin polarized by Andreev reflection (AR) spin spectroscopy. The AR measurements were done in a planar geometry with an InSn superconducting film. A simple reactive growth technique was used to controllably introduce oxygen vacancies into EuO1-x to adjust its carrier concentration. We demonstrate by direct measurements of spin polarization that half-metallicity of EuO1-x can be achieved in the films conductively matched with Si, thus making EuO1-x one of the most attractive materials for silicon-based spintronics.

Panguluri,R.; Santos, T.; Negusse, E.; Dvorak, J.; Idzerda, Y.; Moodera, J.; Nadgorny, B.

2008-01-01

310

Film and interface layer properties of ultraviolet-ozone oxidized hafnia and zirconia gate dielectrics on silicon substrates  

Microsoft Academic Search

We report on the use of ultraviolet-ozone (UVO) oxidation of thin film hafnium and zirconium to fabricate high-dielectric constant (high-k) gate oxides with chemically modified silicon dioxide-based interface layers on silicon (100) substrates. Using x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy, the oxidation state and thickness of the interfacial layer are characterized before and after UVO exposure. Reduction of

David Chi; Paul C. McIntyre

2004-01-01

311

Oxidation of silicon implanted with high-dose aluminum  

SciTech Connect

Si(100) wafers were implanted with Al at 500 C to high doses at multi-energies and were oxidized in 1 atm flowing oxygen at 1000-1200 C. Morphology, structure, and oxidation behavior of the implanted and oxidized Si were studied using optical microscopy, atomic force microscopy, and cross-sectional transmission electron microscopy in conjunction with selected area electron diffraction and energy dispersive x-ray analysis. Large Al precipitates were formed and embedded near the surface region of the implanted Si. Oxidation rate of the Al-implanted Si wafers was lower than that of virgin Si. The unique morphology of the implanted Si results from rpaid Al diffusion and segregation promoted by hot implantation. Reduction of the oxidation rate of Si by Al implantation is attributed to preferential oxidation of Al and formation of a continuous diffusion barrier of Al{sub 2}O{sub 3}.

Yang, Zunde; Du, Honghua [Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering; Withrow, S.P. [Oak Ridge National Lab., TN (United States)

1994-12-31

312

Sputter Deposition of Silicon-Oxide Optical Coatings  

Microsoft Academic Search

Fused silica and Si-O coatings are of interest for use under high flux conditions of laser light. Si-O coatings are sputter deposited from silicon and fused quartz targets using planar magnetrons operated in the rf mode with a variable working-gas mixture of Argon-Oxygen. A series of coatings are prepared on optically flat, fused quartz substrates. Analysis of surface curvature reveals

A F Jankowski; J P Hayes; T E Felter; C Evans; A J Nelson

2002-01-01

313

Effects of oxidation on intergranular phases in silicon nitride ceramics  

Microsoft Academic Search

The effects of oxidation on changes in the secondary phases of two Si3N4 ceramics were investigated by transmission electron microscopy. The Si3N4 materials were oxidized at 1400 C for 168 h in laboratory air. One material, sintered with 5 vol% Yb2O3+0.5 vol% Al2O3, containing a Yb2Si2O7 crystalline secondary phase, displayed no gross changes following oxidation. However, the thickness of the

M. K. Cinibulk; H.-J. Kleebe

1993-01-01

314

Role of Strontium in Oxide Epitaxy on Silicon (001)  

SciTech Connect

Epitaxial oxide-Si heterostructures, which integrate the functionality of crystalline oxides with Si technology, are made possible by a submonolayer of Sr deposited on Si (001). We find by electron diffraction studies using single termination Si wafers that this Sr submonolayer replaces the top layer of Si when deposited at 650 deg. C. Supported by first-principles calculations, we propose a model for the reaction dynamics of Sr on the Si surface and its effect on oxide epitaxy. This model predicts, and we experimentally confirm, an unexplored 25 deg. C pathway to crystalline oxide epitaxy on Si.

Reiner, J. W.; Walker, F. J. [Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284 (United States); Garrity, K. F. [Department of Physics, Yale University, New Haven, Connecticut 06520-8120 (United States); Ismail-Beigi, S.; Ahn, C. H. [Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520-8120 (United States)

2008-09-05

315

Anisotropy and temperature dependence of small angle neutron scattering from silicon-oxide precipitates in silicon  

Microsoft Academic Search

Czochralski grown silicon crystals contain interstitially dissolved oxygen which diffuses on heating to form precipitates of silica. We have examined these precipitates by small angle neutron scattering (SANS) in the Q-range 0.05 -1Q-1. The obtained SANS patterns reveal pronounced anisotropic intensity distributions which resemble the symmetry of the host crystal. The SANS spectra show an anisotropic central peak at Q-1

D. Sieger; H. Tietze-Jaensch; R. Geick; W. Zulehner; A. F. Wright; A. Geyer

1991-01-01

316

Influence of interlayer trapping and detrapping mechanisms on the electrical characterization of hafnium oxide/silicon nitride stacks on silicon  

NASA Astrophysics Data System (ADS)

Al/HfO2/SiNx:H/n-Si metal-insulator-semiconductor capacitors have been studied by electrical characterization. Films of silicon nitride were directly grown on n-type silicon substrates by electron cyclotron resonance assisted chemical vapor deposition. Silicon nitride thickness was varied from 3 to 6.6 nm. Afterwards, 12 nm thick hafnium oxide films were deposited by the high-pressure sputtering approach. Interface quality was determined by using current-voltage, capacitance-voltage, deep-level transient spectroscopy (DLTS), conductance transients, and flatband voltage transient techniques. Leakage currents followed the Poole-Frenkel emission model in all cases. According to the simultaneous measurement of the high and low frequency capacitance voltage curves, the interface trap density obtained for all the samples is in the 1011 cm-2 eV-1 range. However, a significant increase in this density of about two orders of magnitude was obtained by DLTS for the thinnest silicon nitride interfacial layers. In this work we probe that this increase is an artifact that must be attributed to traps existing at the HfO2/SiNx:H intralayer interface. These traps are more easily charged or discharged as this interface comes near to the substrate, that is, as thinner the SiNx:H interface layer is. The trapping/detrapping mechanism increases the capacitance transient and, in consequence, the DLTS measurements have contributions not only from the insulator/substrate interface but also from the HfO2/SiNx:H intralayer interface.

Garca, H.; Dueas, S.; Castn, H.; Gmez, A.; Bailn, L.; Toledano-Luque, M.; Del Prado, A.; Mrtil, I.; Gonzlez-Daz, G.

2008-11-01

317

Influence of interlayer trapping and detrapping mechanisms on the electrical characterization of hafnium oxide/silicon nitride stacks on silicon  

SciTech Connect

Al/HfO{sub 2}/SiN{sub x}:H/n-Si metal-insulator-semiconductor capacitors have been studied by electrical characterization. Films of silicon nitride were directly grown on n-type silicon substrates by electron cyclotron resonance assisted chemical vapor deposition. Silicon nitride thickness was varied from 3 to 6.6 nm. Afterwards, 12 nm thick hafnium oxide films were deposited by the high-pressure sputtering approach. Interface quality was determined by using current-voltage, capacitance-voltage, deep-level transient spectroscopy (DLTS), conductance transients, and flatband voltage transient techniques. Leakage currents followed the Poole-Frenkel emission model in all cases. According to the simultaneous measurement of the high and low frequency capacitance voltage curves, the interface trap density obtained for all the samples is in the 10{sup 11} cm{sup -2} eV{sup -1} range. However, a significant increase in this density of about two orders of magnitude was obtained by DLTS for the thinnest silicon nitride interfacial layers. In this work we probe that this increase is an artifact that must be attributed to traps existing at the HfO{sub 2}/SiN{sub x}:H intralayer interface. These traps are more easily charged or discharged as this interface comes near to the substrate, that is, as thinner the SiN{sub x}:H interface layer is. The trapping/detrapping mechanism increases the capacitance transient and, in consequence, the DLTS measurements have contributions not only from the insulator/substrate interface but also from the HfO{sub 2}/SiN{sub x}:H intralayer interface.

Garcia, H.; Duenas, S.; Castan, H.; Gomez, A.; Bailon, L. [Departamento de Electricidad y Electronica, E.T.S.I. Telecomunicacion, Universidad de Valladolid, Campus 'Miguel Delibes', 47011 Valladolid (Spain); Toledano-Luque, M.; Prado, A. del; Martil, I.; Gonzalez-Diaz, G. [Departamento de Fisica Aplicada III (Electricidad y Electronica), Facultad de Ciencias Fisicas, Universidad Complutense, 28040 Madrid (Spain)

2008-11-01

318

Enhancement of oxidation resistance of NBD 200 silicon nitride ceramics by aluminum implantation  

NASA Astrophysics Data System (ADS)

Silicon nitride (Si3N4) ceramics are leading candidates for high temperature structural applications. They have already demonstrated functional capabilities well beyond the limits of conventional metals and alloys in advanced diesel and turbine engines. However, the practical exploitation of these benefits is limited by their oxidation and associated degradation processes in chemically aggressive environments. Additives and impurities in Si3N4 segregate to the surface of Si3N 4 and accelerate its high temperature oxidation process. This study aims to investigate the oxidation behavior of Norton NBD 200 silicon nitride (hot isostatically pressed with 1 wt.% MgO) and its modification by aluminum surface alloying. NBD 200 samples tribochemically polished to a mirror finish (10 nm) were implanted with 5, 10, 20 and 30 at.% aluminum at multienergies and multi-doses to achieve a uniform implant depth distribution to 200 nm. Unimplanted and aluminum-implanted samples were oxidized at 800--1100C in 1 atm O2 for 0.5--10 hours. Oxidation kinetics was determined using profilometry in conjunction with etch patterning. The morphological, structural and chemical characteristics of the oxide were characterized by various analytical techniques such as scanning electron microscope and energy dispersive x-ray analysis, secondary ion mass spectrometry and x-ray photoelectron spectroscopy. Oxidation of NBD 200 follows parabolic kinetics in the temperature range investigated and the process is diffusion-controlled. The oxide layers are enriched with sodium and magnesium from the bulk of the Si3N 4. The much higher oxidation rate for NBD 200 silicon nitride than for other silicon nitride ceramics with a similar amount of MgO is attributed to the presence of sodium. The rate-controlling mechanism is the outward diffusion of Mg2+ from the grain boundaries to the oxide scale. Aluminum implantation alleviates the detrimental effects of Na+ and Mg2+; not only is the rate of oxidation reduced by up to two orders of magnitude, the surface morphology and the phase characteristics of the oxides are enhanced as well. We have shown that aluminum implantation retards the outward diffusion of Mg2+ and lends a degree of protectiveness to the otherwise non-protective oxide layer. Diffusion studies using Mg-, Na- and Al-implanted silica model specimens have confirmed the effectiveness of Al in inhibiting the diffusion of Mg2+.

Mukundhan, Priya

319

Bismuth Subcitrate Nephrotoxicity  

Microsoft Academic Search

Bismuth subcitrate is a known nephrotoxic agent that may lead to acute oliguric renal failure when ingested in toxic doses. We report a 17-year-old girl who was admitted to the emergency room with complaints of nausea, vomiting, and anuria. She had taken 25 tablets containing 300 mg bismuth subcitrate (total 7.5 g). The patient was managed with hemodialysis started a

Metin Sarikaya; Alper Sevinc; Ramazan Ulu; Fehmi Ates; Fahri Ari

2002-01-01

320

The high-temperature oxidation, reduction, and volatilization reactions of silicon and silicon carbide  

Microsoft Academic Search

A thermochemical analysis was made of the oxidation, reduction, and volatilization reactions which occur in the Si-O-C system. One characteristic feature is the high SiO(g) and SiO(g) + CO(g) pressures at the Si(s)-SiO2 and SiC(s)-SiO2(s) interfaces. Active oxidation with weight losses and passive oxidation with weight gains were found on oxidizing Si(s) and SiC(s) in low oxygen pressures above 1000C.

Earl A. Gulbransen; Sven A. Jansson

1972-01-01

321

Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides.  

PubMed

Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K(3)[Fe(CN)(6)] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO(3) form. PMID:20886983

Salerno, Marco

2010-09-01

322

Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides  

NASA Astrophysics Data System (ADS)

Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K3[Fe(CN)6] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO3 form.

Salerno, Marco

2010-09-01

323

Cathodoluminescence microcharacterization of the radiation-sensitive defect microstructure of in situ buried oxide in silicon  

NASA Astrophysics Data System (ADS)

Cathodoluminescence (CL) spectroscopy in a scanning electron microscope has been used to investigate the radiation-sensitive defect structure of the buried amorphous oxide layer produced by oxygen ion implantation in silicon (Silang1 0 0rang) in comparison with bulk amorphous silicon dioxide (a-SiO2). CL microanalysis allows the defect structure of the buried oxide (BOX) layer to be investigated without removal of the silicon-on-insulator (SOI) top layer. CL emissions are observed at 1.63, 2.10, 2.31 and 2.66 eV and are associated with silicon clusters and nanoparticles that form in the BOX as a result of the post-implantation, high-temperature anneal. CL emission at ~3 eV may be associated with excess silicon and/or inclusions of high-pressure crystalline SiO2 polymorph (coesite) in the BOX near the SiO2-Si substrate. A partially resolved CL emission may also be observed at 1.88 eV and is possibly associated with a native non-bridging oxygen defect of SiO2. CL emission from the confined strained BOX is dominated by defects associated with large surface-to-volume ratio nanoscale silicon clusters and their interfaces. CL spectra from the in situ BOX are electron radiation sensitive. Electron irradiation results in localized trapped charge-induced electric fields which are enhanced within the strained confined BOX layer at nanoscale silicon cluster defects and interfaces. These enhanced electric fields and residual strain near the interfaces can contribute to breakdown of the BOX.

Stevens-Kalceff, Marion A.

2011-06-01

324

Multifunctional silicon-based light emitting device in standard complementary metaloxidesemiconductor technology  

NASA Astrophysics Data System (ADS)

A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 ?m complementary metaloxidesemiconductor technology. This device is capable of versatile working modes: it can emit visible to near infra-red (NIR) light (the spectrum ranges from 500 nm to 1000 nm) in reverse bias avalanche breakdown mode with working voltage between 8.35 V12 V and emit NIR light (the spectrum ranges from 900 nm to 1300 nm) in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.

Wang, Wei; Huang, Bei-Ju; Dong, Zan; Chen, Hong-Da

2011-01-01

325

The effects of oxidizing agents in non-contact synthesis of porous silicon  

NASA Astrophysics Data System (ADS)

A variety of different oxidizing agents have been studied for their ability to aid in the synthesis of porous silicon by noncontact photo-etching in a 40% HF solution. A single substrate, n-type Sb-doped silicon was used as the base material. The single crystal was cleaved into 1cm^2 pieces, which were then processed with a series of different oxidizing agents. The oxidizing agents were selected based upon potential H+ contribution during the etching reaction process. The resulting thin film regions on each sample were characterized using Raman spectroscopy to investigate crystallite size, photoluminescence spectroscopy to confirm light emission from the thin films and surface resistivity, with film thickness determines by spectroscopic ellipsometry measurements. A large range of pore size and structure was achieved, ranging from the nano- to the mesoporous regime.

Bennett, Lauren; Velasquez, Joe, III; Sauncy, Toni

2009-10-01

326

Integration of functional oxide thin film heterostructures with silicon (100) substrates  

NASA Astrophysics Data System (ADS)

The novel functionalities of metal oxides provide the opportunity for the development of next generation optoelectronic, spintronic and a host of other multifunctional devices. A critical issue in the development of practical devices based on metal oxides is the integration of high quality epitaxial oxide thin films with the existing silicon technology which is based on silicon (100) substrates. However, silicon is not suitable for epitaxial growth of oxides owing to its tendency to readily form an amorphous oxide layer at the film-substrate interface. The oxide films deposited directly on silicon exhibit poor crystallinity and are not suitable for device applications. To overcome this challenge, appropriate substrate templates must be developed for growth of oxide thin films on silicon substrates. The present work is focused on developing integration methodology of functional oxides with Si (100) substrates using an yttria-stabilized zirconia (YSZ) template layer. If the deposition conditions are controlled properly, YSZ can be grown epitaxially on silicon substrates even if the native oxide is not etched prior to deposition. This is believed to occur by reaction between zirconium and native silicon dioxide. These Si (100) substrates with epitaxial YSZ template layer can be used to grow functional oxide thin films. The above approach has been used to integrate zinc oxide (ZnO) thin films with Si (100) substrates. The wide band gap (3.4 eV), large exciton binding energy (60 meV) and room temperature ferromagnetism make ZnO a potential candidate for a host of next generation optoelectronic and spintronic devices. A thorough study on growth and properties of ZnO films on YSZ buffered Si (100) substrates was performed. The ZnO and YSZ films were deposited by pulsed laser deposition (PLD) technique. Detailed characterization of the deposited films was done using x-ray diffraction, transmission electron microscopy (TEM), electrical measurements and photoluminescence spectroscopy. Using YSZ buffer layer, we have been able to epitaxially integrate both non-polar (c-plane) and semi-polar (r-plane) ZnO films with Si (100) substrates. It was observed that, depending on the oxygen pressure during the deposition, ZnO can grow in two different crystallographic orientations (c-plane or r-plane) on YSZ buffered silicon. Experiments carried out to elucidate the role of oxygen pressure indicated that the crystallographic orientation of ZnO depends on the nature of atomic termination of YSZ layer. It has been proposed that crystallographic orientation of ZnO is controlled by chemical free energy associated with the ZnO/YSZ interface. In order to form p-n junction with n-type ZnO, another multifunctional oxide La0.67Sr0.33MnO3 (LSMO) was epitaxially integrated with Si (100) substrates. LSMO is a p-type materials and exhibits interesting properties such as semiconductor to metal transition (SMT), room temperature ferromagnetism and colossal magneto resistance (CMR). Junctions based on CMR materials are of special interest, because their electrical and magnetic properties can be modulated by external electric and magnetic fields. It has been demonstrated that epitaxial nonpolar a-plane ZnO films can be grown on LSMO integrated with Si (100) substrates.

Aggarwal, Ravi

327

Bias-stimulated nucleation of silver prepared by pulsed arc deposition on silicon oxide  

SciTech Connect

The nucleation and interface formation between Ag films and native silicon oxide have been studied with x-ray and ultraviolet photoelectron spectroscopies. Silver was deposited stepwise onto silicon native oxide by pulsed arc deposition technique onto grounded and biased substrates resulting in kinetic energy of incident silver ions of 95 and 720 eV, respectively. We show that an increase in the kinetic energy of silver ions leads to more homogeneous nucleation and earlier coalescence of Ag films due to surface defect generation and preferential sputtering of oxygen. In addition, deposition from high energy beam results in the formation of an extended transition layer containing a mixture of Ag and Si oxide that might be beneficial in improving adhesion of Ag films.

Romanyuk, Andriy; Steiner, Roland; Thommen, Verena; Oelhafen, Peter; Mathys, Daniel [Institute of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland); Microscopy Center, University of Basel, Klingelbergstrasse 50/70, 4056 Basel (Switzerland)

2006-10-01

328

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

SciTech Connect

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.

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

329

Tunable silicon photonic wires fabricated by contact lithography and thermal oxidation  

NASA Astrophysics Data System (ADS)

Contact lithography with i-line (365 nm) or DUV (248 nm) is widely used in laboratories for prototyping. The achievable line width of 300 nm is sufficient for photonic wires, but a process with larger line width is more controllable. The sidewall roughness induced by the lithography and by the following etching steps results in high optical losses. Thermal oxidation is known to smoothen the silicon surface. The oxidation also consumes silicon, so that the photonic wire will shrink and a wider lithography linewidth can be applied. The silicon dioxide is used as a low loss cladding, which further reduces the refractive index contrast, so that the remaining roughness causes less losses. Single mode silicon nanowires with 500nm by 200nm cross section and optical losses of 2dB/cm were produced. The index contrast is still high enough for small bending radii for highly integrated photonic devices. Sharp branches used in Y-couplers can not be fabricated by this oxidation technique, due to the waveguide shrinkage. 3dB-couplers are easily realized by multimode interference (MMI)-couplers, with the output branches sufficiently apart. Using such couplers, Mach-Zehnder interferometers were fabricated. For electric contacts, the SiO2-cladding is locally removed and ZnO and Al electrodes are applied. The c-axis of sputtered ZnO grows preferentially perpendicular to the surface, which allows to utilize the electro optic effect.

Horn, Oliver; Amthor, Julia; Lipka, Timo; Mller, Jrg

2009-05-01

330

Correlations between Self-Interstitials and Vacancies during Thermal Oxidation in Silicon  

NASA Astrophysics Data System (ADS)

It is generally accepted that there are four relations between self-interstitials and vacancies during thermal oxidation in silicon; local equilibrium between self-interstitials and vacancies, oxidation-enhanced and -retarded diffusions (OED and ORD) and oxidation stacking faults (OSF). From a mathematical point of view on these relations, a method for their analysis was established. The results of this study clearly indicate some OED, ORD and OSF to be governed by only an interstitialcy or vacancy mechanism. A method for obtaining analytical solutions is also discussed.

Okino, Takahisa

1991-05-01

331

Dependence of cryogenic strength of hydroxide catalysis bonded silicon on type of surface oxide  

NASA Astrophysics Data System (ADS)

Hydroxide catalysis bonding is a joining technique used in the construction of highly stable opto-mechanical systems including quasi-monolithic silica suspensions for first and second generation gravitational wave detectors. Future generations of detector are likely to operate at cryogenic temperatures necessitating a change in testmass/suspension material. A promising candidate material is silicon, which requires an oxide surface layer for hydroxide catalysis bonding to be reliable. Here, we present first results showing the influence of the type of oxide layer applied on bond strength, measured at room temperature and 77 K, and identify preferred oxide deposition methods.

Beveridge, N. L.; van Veggel, A. A.; Cunningham, L.; Hough, J.; Martin, I. W.; Nawrodt, R.; Reid, S.; Rowan, S.

2013-01-01

332

Influence of Fluorine on the Conductivity and Oxidation of Silicon Nanomembranes after Hydrofluoric Acid Treatment  

NASA Astrophysics Data System (ADS)

After immersion in hydrofluoric acid, the sheet resistance of a 220-nm-thick silicon nanomembrane, measured in dry air by van der Pauw method, drops around two orders of magnitude initially, then increases and reaches the level of a sample with a native oxide surface in about one month. The surface component and oxidation rate are also characterized by x-ray photo electronic spectroscopy measurement. Fluorine is found to play a significant role in improving conductivity and has no apparent influence on the oxidation rate after hydrofluoric acid treatment.

Zhao, Xiang-Fu; Han, Ping; Zhang, Rong; Zheng, You-Dou

2011-08-01

333

Subattoampere current induced by single ions in silicon oxide layers of nonvolatile memory cells  

SciTech Connect

A single ion impinging on a thin silicon dioxide layer generates a number of electron/hole pairs proportional to its linear energy transfer coefficient. Defects generated by recombination can act as a conductive path for electrons that cross the oxide barrier, thanks to a multitrap-assisted mechanism. We present data on the dependence of this phenomenon on the oxide thickness by using floating gate memory arrays. The tiny number of excess electrons stored in these devices allows for extremely high sensitivity, impossible with any direct measurement of oxide leakage current. Results are of particular interest for next generation devices.

Cellere, G.; Paccagnella, A.; Larcher, L.; Visconti, A.; Bonanomi, M. [Dipartimento di Ingegneria dell'Informazione (DEI), Universita di Padova, 35100 Padova (Italy); Dipartimento Scienze e Metodi dell'Ingegneria, Universita di Modena e Reggio Emilia, 42100 Reggio Emilia (Italy); STMicroelectronics, 20041 Agrate Brianza (Milan) (Italy)

2006-05-08

334

Tungsten oxide as a p-type window material in amorphous silicon solar cells  

Microsoft Academic Search

A p-type amorphous tungsten oxide (p-a-WO3) film was prepared using a vacuum thermal evaporator with a WO3 source. By replacing a 10 nm-thick p-type amorphous silicon carbide window layer of a pin-type amorphous silicon based solar cell with a 10 nm-thick p-a-WO3 film, the short circuit current density increased from 12.75 to 13.83 mA\\/cm2. Although the open circuit voltage was

Liang Fang; Seung Jae Baik; Jeong Won Kim; Seung Hyup Yoo; Jin-Wan Jeon; Sang Jung Kang; Yoon Hak Kim; Koeng Su Lim

2010-01-01

335

On the nature of point defects and the effect of oxidation on substitutional dopant diffusion in silicon  

NASA Astrophysics Data System (ADS)

An extensive analysis of the substitutional dopant diffusion phenomena in silicon during oxidation is presented. The analysis covers qualitative as well as quantitative aspects of the oxidation-enhanced and -retarded diffusion (OED and ORD) phenomena, and examines three different possible assumptions that can be made on the nature of the silicon thermal equilibrium point defect species: silicon self-interstitials (I) only, vacancies (V) only, coexistence of I and V. The only consistent way to interpret all properly documented OED/ORD data is to assume that I and V coexist under oxidation as well as under thermal equilibrium conditions at high temperatures.

Tan, T. Y.; Gsele, U.; Morehead, F. F.

1983-06-01

336

Oxidation and sulfidation resistant alloys with silicon additions  

SciTech Connect

The Albany Research Center (ARC) has considerable experience in developing lean chromium, austenitic stainless steels with improved high temperature oxidation resistance. Using basic alloy design principles, a baseline composition of Fe-16Cr-16Ni-2Mn-1Mo alloys with Si and Al addition at a maximum of 5 weight percent was selected for potential application at temperatures above 700C for supercritical and ultra-supercritical power plant application. The alloys were fully austenitic. 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 700C to 800C. Oxidation resistances of alloys with Si only additions were outstanding, particularly at 800C (i.e., these alloys possessed weight gains 4 times less than a standard type-304 alloy). In addition, Si alloys pre-oxidized at 800C, showed a zero weight gain in subsequent testing for 1000 hours at 700C. Similar improvements were observed for Si only alloy after H2S exposure at 700C compared with type 304 stainless steel. 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 at ARC. Depth profile analysis and element concentration profiles (argon ion etching/x-ray photoelectron spectroscopy) were conducted on oxidized specimens and base material at the National Energy Technology Laboratory.

Dunning, John S.; Alman, David E.; Poston, J.A., Jr. (NETL); Siriwardane, R. (NETL)

2003-01-01

337

Sintering of silicon nitride ceramics with magnesium silicon nitride and yttrium oxide as sintering aids  

Microsoft Academic Search

Silicon nitride (Si3N4) ceramics had been produced through pressureless sintering and hot-pressing sintering with MgSiN2-Y2O3 or only MgSiN2 as sintering aids. The influences of the amount of MgSiN2 and Y2O3 and sintering methods on the properties of Si3N4 ceramics were investigated. The results show that the bend strength of Si3N4 ceramic fabricated through pressureless sintering at 1820 C for 4

J. Jiang; J. Y. Xu; G. H. Peng; H. R. Zhuang; W. L. Li; S. Y. Xu; Y. J. Mao

2011-01-01

338

Silicon and chromium depletion during the long-term oxidation of thin-sectioned austenitic steel  

SciTech Connect

Electron-probe microanalysis (EPMA) measurements are reported of the residual silicon and chromium concentrations in thin sections (0.38 mm) of a 20Cr-25Ni-Nb-stabilized austenitic steel oxidized in a CO{sub 2}/1%CO environment for maximum periods of around 40,000 hr at temperatures in the range 900 to 950 C. The depletion profiles obtained have been analyzed using the theoretical treatment of Whittle and Cowen-Webster. It is found that silicon depletion occurs slowly because of the low rate of thickening of the silica interlayer formed below the much-thicker, chromia-surface layer. This, coupled with relatively rapid diffusion within the steel, leads to a flat depletion profile. By contrast, the more rapid oxidation of chromium develops large concentration gradients of that element in the alloy in the vicinity of the oxide-metal interface. In each case, the solute concentration at this interface was very much larger than that for equilibrium with the respective oxide, indicating that the oxidation kinetics were determined by transport within the oxide layer rather than in the steel. In all the examples studied, the theoretical analysis produced good agreement wit the depletion measurements using oxidation rate constants consistent with the metallographic measurements and diffusion coefficients of similar value to those reported in the literature.

Evans, H.E. [Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials; Donaldson, A.T. [BNFL-Magnox Generation, Berkeley (United Kingdom)

1998-12-01

339

Influence of Electrostatic Charge on Recombination Lifetime and Native Oxide Growth on HF-Treated Silicon Wafers  

Microsoft Academic Search

This paper reports on the influence of electrostatic charge on the time-dependent change in the hydrogen-terminated surface of HF-treated silicon wafers. The change in the hydrogen-terminated silicon surfaces were evaluated from the changes in recombination lifetime and the rate of native oxide growth. It is known that electrostatic charges are generated on silicon wafers by wet processing, such as HF

Nobue Araki

2009-01-01

340

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

Microsoft Academic Search

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 1100C, isolated Si-nanocrystals are formed. The thin film layers containing these crystals act as n-type or

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

341

Pr doped bismuth ferrite ceramics with enhanced multiferroic properties  

Microsoft Academic Search

Pr modified Bi0.9-xLa0.1PrxFeO3 (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

P. Uniyal; K. L. Yadav

2009-01-01

342

High temperature oxidation of Fe9Cr1Mo steel in stagnant liquid leadbismuth at several temperatures and for different lead contents in the liquid alloy  

Microsoft Academic Search

This research project deals with the feasibility studies concerning the construction of an hybrid reactor for the transmutation of long-lived radioactive wastes. In this context, the liquid leadbismuth eutectic (LBE) is considered to be a good candidate for the spallation target material needed for the neutrons production necessary to the transmutation. In this hybrid reactor, the LBE, which is enclosed

L. Martinelli; T. Dufrenoy; K. Jaakou; A. Rusanov; F. Balbaudcelerier

2008-01-01

343

Metal-oxide-high-k-oxide-silicon memory structure using an Yb2O3 charge trapping layer  

Microsoft Academic Search

In this letter, we proposed a metal-oxide-high-k-oxide-silicon (MOHOS)-type memory structure using a high-k Yb2O3 charge trapping layer for flash memory applications. When using Fowler-Nordheim for charging and discharging, the high-k Yb2O3 MOHOS-type memories that had been annealed at 800 C exhibited large threshold voltage shifting (memory window of ~2.2 V) and excellent data retention (charge loss of ~6% measured time

Tung-Ming Pan; Jing-Wei Chen

2008-01-01

344

REVIEWS OF TOPICAL PROBLEMS: Structure of silicon/oxide and nitride/oxide interfaces  

NASA Astrophysics Data System (ADS)

We systematize and generalize modern concepts on the atomic structure of silicon/insulator (Si/SiO2, Si/SiOxNy) and insulator/insulator (Si3N4/SiO2) interfaces in the structures underlying the operation of silicon devices.

Gritsenko, Vladimir A.

2009-09-01

345

Bismuth in the United States.  

National Technical Information Service (NTIS)

Domestic bismuth supply was projected from production figures for the ores in which it occurs--copper, lead, zinc, and tungsten. Published and unpublished data concerning host ores were examined to determine bismuth reserves and resources, and mine produc...

F. H. Persse

1970-01-01

346

Development of High Quality P-Type Hydrogenated Amorphous Silicon Oxide Film and Its Use in Improving the Performance of Single Junction Amorphous Silicon Solar Cells  

Microsoft Academic Search

By using radio frequency plasma enhanced chemical vapour deposition (RF-PECVD) method (13.56 MHz) we have developed high quality wide band gap p-type hydrogenated amorphous silicon oxide (p-a-SiO:H) films having characteristics suitable for use as the window layer for single and multijunction amorphous silicon (a-Si) solar cells. The films have been characterized in detail. The p-a-SiO:H films having thickness >=100

Arindam Sarker; Asok K. Barua

2002-01-01

347

Fabrication and functionalization of nanochannels by electron-beam-induced silicon oxide deposition.  

PubMed

We report on the fabrication and electrical characterization of functionalized solid-state nanopores in low stress silicon nitride membranes. First, a pore of approximately 50 nm diameter was drilled using a focused ion beam technique, followed by the local deposition of silicon dioxide. A low-energy electron beam induced the decomposition of adsorbed tetraethyl orthosilicate resulting in site-selective functionalization of the nanopore by the formation of highly insulating silicon oxide. The deposition occurs monolayer by monolayer, which allows for control of the final diameter with subnanometer accuracy. Changes in the pore diameter could be monitored in real time by scanning electron microscopy. Recorded ion currents flowing through a single nanopore revealed asymmetry in the ion conduction properties with the sign of the applied potential. The low-frequency excess noise observed at negative voltage originated from stepwise conductance fluctuations of the open pore. PMID:17129050

Danelon, Christophe; Santschi, Christian; Brugger, Jrgen; Vogel, Horst

2006-12-01

348

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

349

Biocompatible magnetofluorescent probes: luminescent silicon quantum dots coupled with superparamagnetic iron(III) oxide.  

PubMed

Luminescent silicon quantum dots (SiQDs) are gaining momentum in bioimaging applications, based on their unique combination of optical properties and biocompatibility. Here, we report the development of a multimodal probe that combines the optical properties of silicon quantum dots with the superparamagnetic properties of iron oxide nanoparticles to create biocompatible magnetofluorescent nanoprobes. Multiple nanoparticles of each type are coencapsulated within the hydrophobic core of biocompatible phospholipid-polyethyleneglycol (DSPE-PEG) micelles. The size distribution and composition of the magnetofluorescent nanoprobes were characterized by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Enhanced cellular uptake of these probes in the presence of a magnetic field was demonstrated in vitro. Their luminescence stability in a prostate cancer tumor model microenvironment was demonstrated in vivo. This paves the way for multimodal silicon quantum-dot-based nanoplatforms for a variety of imaging and delivery applications. PMID:20738120

Erogbogbo, Folarin; Yong, Ken-Tye; Hu, Rui; Law, Wing-Cheung; Ding, Hong; Chang, Ching-Wen; Prasad, Paras N; Swihart, Mark T

2010-09-28

350

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

PubMed

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

Pennelli, G; Totaro, M; Piotto, M

2012-01-26

351

Passivation-Induced Subthreshold Kink Effect of Ultrathin-Oxide Low-Temperature Polycrystalline Silicon Thin Film Transistors  

Microsoft Academic Search

Polycrystalline silicon thin-film transistors (poly-Si TFTs) with an ultrathin electron cyclotron resonance plasma- oxidized gate oxide have been fabricated. These ultrathin gate oxide poly-Si TFTs demonstrate better gate controllability and short-channel effect suppression, as compared with conventional thick-gate oxide poly-Si TFTs. A subthreshold kink effect has been observed in these ultrathin gate oxide poly-Si TFTs after NH3 plasma treatment for

Mon-Chin Tsai; Ta-Chuan Liao; I-Che Lee; Huang-Chung Cheng

2011-01-01

352

Kinetics of thermal oxidation of silicon nitride powders  

SciTech Connect

The kinetics of thermal oxidation of H.C. Starck M-11 and Ube SN-E10 Si{sub 3}N{sub 4} powders was evaluated in the temperature range 650--1,200 C using isothermal and nonisothermal thermogravimetric analysis, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Between 700 and 1,200 C, the isothermal kinetics was modeled equally well using the Ginstling-Brounshtein and Zuravlev-Lesokhin-Tempel`man equations. Despite their similar particle sizes and surface areas, the two powders exhibited different oxidation kinetics. The activation energies for oxidation of the M-11 and SN-E10 powders were determined to be 400 and 540 kJ/mol, respectively, between 1,000 and 1,200 C, and 230 and 260 kJ/mol, respectively, between 700 and 1,000 C. the parabolic rate constants for oxidation of the two powders were comparable to those reported in the literature for monolithic, chemically-vapor-deposited Si{sub 3}N{sub 4} at the higher temperatures. At lower temperatures, the oxidation kinetics of the M-11 powder was nearly linear, whereas the kinetics of the SN-E10 powder remained power-law dependent.

Butt, D.P.; Albert, D.; Taylor, T.N. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

1996-11-01

353

Quantum Conductance in Silicon Oxide Resistive Memory Devices  

PubMed Central

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.

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

2013-01-01

354

Microstructure and oxidation behaviour of HIPed silicon nitride  

SciTech Connect

Dense beta-Si3N4 based ceramics in the Y-Si-O-N have been fabricated using a commercial glass-encapsulated hot-isostatic pressing process. Compositions were tailored to lie within the Si3N4-Si2N2O-Y2Si2O7 compatibility triangle. Crystallization of the intergranular glassy phase, to Y2Si2O7, was found to occur during the cooling segment of the HIP cycle. HIPed ceramics demonstrated excellent resistance to oxidation at temperatures up to 1450 C, although surface contamination during HIPing resulted in a degradation of the oxidation resistance. 11 refs.

Plucknett, K.P.; Lewis, M.H.

1992-10-01

355

Indentation and oxidation studies on silicon nitride joints  

SciTech Connect

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.

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

356

Passive-oxidation kinetics of high-purity silicon carbide from 800 to 1100 C  

SciTech Connect

Highly textured chemically vapor-deposited silicon carbide (CVD-SiC) thick films were oxidized and compared to single-crystal SiC and single-crystal silicon. The oxidation rates of the (111) face of the cubic CVD-SiC were the same as those of the (0001) face of the single-crystal SiC. Similarly, the opposite faces of the two materials, ({bar 1}{bar 1}{bar 1}) and (000{bar 1}), also oxidized at nominally the same rates. The ({bar 1}{bar 1}{bar 1}) and (000{bar 1}) faces oxidized much faster than their opposite (111)/(0001) faces. Ellipsometry measurements and kinetic results implied that differences existed between the oxides that grew on the opposite faces. A regression method was developed to analyze the oxide thickness versus time versus temperature behavior of the specimens simultaneously. This technique was compared to typical methods for analyzing temperature-dependent processes and estimated temperature-dependent parameters (e.g., activation energy) and their errors more accurately.

Ramberg, C.E.; Cruciani, G.; Spear, K.E.; Tressler, R.E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering; Ramberg, C.F. Jr. [Univ. of Pennsylvania, Kennett Square, PA (United States)

1996-11-01

357

Locally oxidized silicon surface-plasmon Schottky detector for telecom regime.  

PubMed

We experimentally demonstrate an on-chip nanoscale silicon surface-plasmon Schottky photodetector based on internal photoemission process and operating at telecom wavelengths. The device is fabricated using a self-aligned approach of local-oxidation of silicon (LOCOS) on silicon on insulator substrate, which provides compatibility with standard complementary metal-oxide semiconductor technology and enables the realization of the photodetector and low-loss bus photonic waveguide at the same fabrication step. Additionally, LOCOS technique allows avoiding lateral misalignment between the silicon surface and the metal layer to form a nanoscale Schottky contact. The fabricated devices showed enhanced detection capability for shorter wavelengths that is attributed to increased probability of the internal photoemission process. We found the responsivity of the nanodetector to be 0.25 and 13.3 mA/W for incident optical wavelengths of 1.55 and 1.31 ?m, respectively. The presented device can be integrated with other nanophotonic and nanoplasmonic structures for the realization of monolithic opto-electronic circuitry on-chip. PMID:21604793

Goykhman, Ilya; Desiatov, Boris; Khurgin, Jacob; Shappir, Joseph; Levy, Uriel

2011-05-23

358

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof  

DOEpatents

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications is disclosed. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al[sub x]N[sub y]O[sub z] layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al[sub x]N[sub y]O[sub z] layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Sarin, V.K.

1990-08-21

359

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof  

SciTech Connect

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al.sub.x N.sub.y O.sub.z layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al.sub.x N.sub.y O.sub.z layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Sarin, Vinod K. (Lexington, MA)

1990-01-01

360

Thermal oxide growth on silicon: Intrinsic stress and silicon cleaning effects  

NASA Astrophysics Data System (ADS)

This paper summarizes the experimental results and discusses the implications of recent research on two topics related to Si oxidation: mechanical stress effects and the influence of impurities on the Si surface. For stress measurement, a double beam optical technique is used to measure the strain in the Si substrate due to the film stress. An intrinsic SiO2 stress is measured which increses with decreasing oxidation temperature. Controversy exists about whether the intrinsic stress affects transport of oxidant or the interface reaction; arguments for both views are presented. A combination of in-situ ellipsometry and contact angle measurements performed on a Si surface which is used to determine the role of HF in Si cleaning process. A fluorocarbon films was found to replace the removed SiO2, and the fluorocarbon renders the Si surface hydrophobic and amenable to the growth of a high quality SiO2 film for device applications.

Irene, E. A.

1988-09-01

361

Improved Structural Silicon Nitride Materials Containing Rare Earth Oxides.  

National Technical Information Service (NTIS)

A ceramic composition suitable for use as a high-temperature structural material in apparatus exposed to oxidizing atmospheres at temperatures of 400 to 1600 exp 0 C is described. It is found within the triangular area ABCA of the Si sub 3 N sub 4 -SiO su...

C. A. Anderson

1979-01-01

362

Silicon and tungsten oxide nanostructures for water splitting  

Microsoft Academic Search

Inorganic semiconductors are promising materials for driving photoelectrochemical water-splitting reactions. However, there is not a single semiconductor material that can sustain the unassisted splitting of water into H2 and O2. Instead, we are developing a three part cell design where individual catalysts for water reduction and oxidation will be attached to the ends of a membrane. The job of splitting

Karla R. Reyes Gil; Joshua M. Spurgeon; Nathan S. Lewis

2009-01-01

363

Topographic control on silicone surface using chemical oxidization method  

NASA Astrophysics Data System (ADS)

The paper describes a wet process for modifying the surface of polydimethylsiloxane (PDMS) using H2SO4/HNO3 solutions. The oxidation on the surface of PDMS was confirmed by the examinations of Fourier transform infrared spectrometry (FTIR), contact angle of water drop and X-ray photoelectron spectroscopy (XPS). The hydrophobic surface of pristine PDMS was not only changed to hydrophilic, but also formed wrinkles on it after chemical modification. Bilayer systems, stiff oxidized PDMS layers were capped on soft PDMS foundations, would generate easily compressive stresses due to the large difference in volumetric contraction rates and led to form wrinkles on the surface. Experimental results demonstrated the periodicity of wrinkles was controllable by controlling the duration of oxidation. Therefore, wrinkles could be arranged orderly by the guidance of external forces before oxidization. The potential technology for generating and ordering wrinkles on the PDMS surface is valuable in the applications of pressure sensors, biology, micro-optics and nano-/micro-fabrication in the future.

Shih, Teng-Kai; Ho, Jeng-Rong; Chen, Chia-Fu; Whang, Wha-Tzong; Chen, Chien-Chung

2007-10-01

364

Effect of hydrogen-related impurities on the thermal behavior of mechanical stress in silicon oxides suitable for integrated optics  

Microsoft Academic Search

Silicon oxide films were deposited by plasma enhanced chemical vapor deposition on crystalline silicon substrates from a mixture of silane and nitrous oxide. Substrate temperature and [N2O]\\/[SiH4] precursor gas flow ratio were varied between 200-350 C and 5.5-110, respectively. Rapid thermal annealing at 900 C to achieve impurity effusion led to significant changes in the dependence of the mechanical stress

C. Domnguez; J. A. Rodrguez; M. Riera; A. Llobera; B. Daz

2003-01-01

365

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

Microsoft Academic Search

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

Tetsuya Homma

1996-01-01

366

Infrared spectroscopy study of low-dielectric-constant fluorine-incorporated and carbon-incorporated silicon oxide films  

Microsoft Academic Search

Bonding characteristics of low-dielectric-constant (low-k) fluorine-incorporated silicon oxide (SiOF) and carbon-incorporated silicon oxide (SiOC) films prepared by plasma enhanced chemical vapor deposition were investigated by Fourier transform infrared spectroscopy (FTIR). The frequency of Si-O stretching vibration mode in SiOF film shifted to higher wave number (blueshift) with the increase of fluorine incorporation, while that in SiOC film shifted to lower

Yoon-Hae Kim; Moo Sung Hwang; Hyeong Joon Kim; Jin Yong Kim; Young Lee

2001-01-01

367

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

NASA Astrophysics Data System (ADS)

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.

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

368

Structure and luminescence evolution of annealed Europium-doped silicon oxides films.  

PubMed

Europium (Eu)-doped silicon oxide films with Eu concentrations from 2.1 to 4.7 at. % were deposited by electron beam evaporation. The Eu related luminescence from the films was found to be sensitive to the evolution of film microstructures at different annealing temperatures. Luminescence centers in the films changed from defects of silicon oxides to 4f(6)5d-4f(7)(8S(7/2)) transition of Eu2+ after the films annealed in N2 at temperature higher than 800 C. The evolution of luminescence centers was attributed to the formation of europium silicate (EuSiO3), which was confirmed by x-ray photoelectron spectroscopy, x-ray diffraction, time resolved photoluminescence, and transmission electron microscopy. PMID:21196996

Li, Dongsheng; Zhang, Xuwu; Jin, Lu; Yang, Deren

2010-12-20

369

Determination of Mean Thickness of an Oxide Layer on a Silicon Sphere by Spectroscopic Ellipsometry  

NASA Astrophysics Data System (ADS)

One of the biggest obstacles to reduce the uncertainty of the Avogadro constant NA is such that there will be an oxide layers on the surface of a silicon sphere. The thickness of this layer is measured by a modified spectroscopic ellipsometer, which can eliminate the influence of the curved surface, and the results are calibrated by x-ray reflectivity. Fifty positions distributed nearly uniformly on the surface of the silicon sphere are measured twice. The results show that the mean thickness of the overall oxide layer is 3.75 nm with the standard uncertainty of 0.21 nm, which means that the relative uncertainty component of NA owing to this layer can be reduced to 1.2 10-8.

Zhang, Ji-Tao; Li, Yan; Luo, Zhi-Yong; Wu, Xue-Jian

2010-05-01

370

Efficient self-assembly of transition metal oxide nanoclusters on silicon substrates  

Microsoft Academic Search

Self-assembled monolayers (SAMs) of nanoclusters (<10 nm) on silicon wafer have been prepared via simply immersing the substrate into a FeCl3\\/HCl solution. The clusters are hydrous iron oxide resulting from the hydrolysis of FeCl3, and their deposition is driven by the electrostatic attraction between the clusters and the substrate, the surface groups of which are oppositely charged at suitable pH

Linyou Cao; Yang Chai; Pingjian Li; Zhiyong Shen; Jinlei Wu

2005-01-01

371

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

Microsoft Academic Search

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,

Glenn M. Tom; James V. McManus

1991-01-01

372

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

Microsoft Academic Search

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,

Glenn M. Tom; James V. McManus

1992-01-01

373

Irradiation induced pulsations of reverse biased metal oxide/silicon structures  

SciTech Connect

Specific electronic features have been found in structures consisting of metal oxide layers on silicon substrates upon swift heavy ion irradiation. These features are linked to the appearance of radiation-induced negative differential resistances in the structures. In the reversed bias direction they show high frequency current pulsations at around {approx}10 kHz frequency. Their amplitude increases with increasing applied voltage. The pulsation frequency also shows a small increase. The current amplitude depends on the ion fluence and flux.

Fink, D.; Kiv, A.; Fuks, D.; Tabacnics, M.; Rizutto, M. de A; Silva, A. de O D; Chandra, A.; Golovanov, V.; Ivanovskaya, M.; Khirunenko, L. [Hahn-Meitner Institut, Glienicker Str. 100, 14109 Berlin (Germany); Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Universidade Federal de Sao Paulo, Cidade Universitaria, 05508090 Sao Paulo (Brazil); Department of Physics and Astrophysics, Delhi University, Delhi 110 007 (India); South-Ukrainian State University, 26 Staroportofrankovskaya Str., Odessa 65008 (Ukraine); Belarusian State University, 14 Leningradskaya, 22080 Minsk (Belarus); Institute of Physics, 122 Prospect Nauki, 03028 Kiev (Ukraine)

2007-08-20

374

Enhancement of oxidation resistance of NBD 200 silicon nitride ceramics by aluminum implantation  

Microsoft Academic Search

Silicon nitride (Si3N4) ceramics are leading candidates for high temperature structural applications. They have already demonstrated functional capabilities well beyond the limits of conventional metals and alloys in advanced diesel and turbine engines. However, the practical exploitation of these benefits is limited by their oxidation and associated degradation processes in chemically aggressive environments. Additives and impurities in Si3N4 segregate to

Priya Mukundhan

2000-01-01

375

Inelastic electron scattering in amorphous silicon nitride and aluminum oxide with multiple-scattering corrections  

Microsoft Academic Search

Electron-energy-loss measurements for an amorphous chemical-vapor-deposited silicon nitride film and evaporated sapphire in the broad energy range 1-200 eV are investigated. A method, not requiring the zero-loss peak, to remove the multiple scattering is discussed, applied, and the optical constants obtained. An Elliot-type model used with aluminum oxide gives a valence-exciton binding energy of 1.36+\\/-0.2 eV with a band gap

Peteris Livins; T. Aton; S. E. Schnatterly

1988-01-01

376

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

Microsoft Academic Search

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

Avi Shalav; Taehyun Kim; Robert G. Elliman

2011-01-01

377

Electrical characteristics of silicon-tin oxide heterojunctions prepared by chemical vapor deposition  

Microsoft Academic Search

It is pointed out that transparent conductors, such as tin oxide, belong to an unusual class of materials. In addition to being conducting and transparent, these materials have also the ability to form very high barriers on such semiconductors as silicon. The present investigation has mainly three objectives. One is related to the preparation of a set of reproducible n-Si\\/SnO2

S. Varma; K. V. Rao; S. Kar

1984-01-01

378

Nafion\\/silicon oxide\\/phosphotungstic acid nanocomposite membrane with enhanced proton conductivity  

Microsoft Academic Search

Nafion-silicon oxide (SiO2)-phosphotungstic acid (PWA) composite membrane has been synthesized to improve Nafion based proton exchange membrane fuel cell (PEMFC) performance. The objective of the study is to fabricate Nafion-SiO2-PWA nanocomposite membrane using solgel reaction. The composite is composed of the mixture of Nafion solution, tetra ethoxy orthosilane (TEOS) and PWA solution. The mixed solution was casted at certain temperature

A. Mahreni; A. B. Mohamad; A. A. H. Kadhum; W. R. W. Daud; S. E. Iyuke

2009-01-01

379

Optimization of indium tin oxide by pulsed DC power on single junction amorphous silicon solar cells  

Microsoft Academic Search

We investigated the optimal deposition conditions of a thin indium tin oxide (ITO) film on an amorphous silicon (a-Si) single-junction solar cell using pulsed DC magnetron sputtering. Thin ITO films were deposited while power, deposition time, pressure, gas flow and temperature were varied to find such conditions. The efficiency of a-Si solar cells with ITO films was 6.65% at the

Rebecca K. Carlson; Yunsic Shim; William B. Ingler

2011-01-01

380

Surface reactions of (sub)monolayers of small organic species on oxidized silicon  

Microsoft Academic Search

The preparation of (sub)monolayers of small and short-chain organic molecules on oxide-covered silicon is described. The molecular end groups and their chemical reactions were characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, spectroscopic ellipsometry (IR-UV), laserinduced desorption of monolayers (LIDOM), X-ray photoelectron spectroscopy (XPS), and contact-angle experiments. Surface species were identified and their reactions were monitored by FTIR

N. Salingue; D. Lingenfelser; P. Prunici; P. Hess

2009-01-01

381

Effects of plasma treatment on the precipitation of fluorine-doped silicon oxide  

Microsoft Academic Search

Precipitates were observed on the surface of fluorine-doped silicon oxide (SiOF) films. These precipitates are flake-type and hexagonal in shape, showing up rapidly after initiation, and clustered at the wafer center. Post-deposition N2O plasma treatment (post-plasma treatment) was found to be most effective in inhibiting the appearance of precipitates. In this paper, effects of post-deposition N2O plasma treatment on the

Jun Wu; Ying-Lang Wang; Cheng-Tzu Kuo

2008-01-01

382

Deposition damage evaluation of fluorine doped silicon oxide using simple damage monitoring system  

Microsoft Academic Search

An arcing defect, generated during inter-metallic dielectric (IMD) fluorine doped silicon oxide (SiOF) film deposition, is fatal damage which occurs during the plasma enhanced deposition process. After IMD SiOF film deposition on the metal patterned wafer of logic device structure, the arcing defect is monitored using the KLA defect detecting tool. From KLA tool, it can be seen that the

Dong-Hwan Kim; Beomjun Kim; Jeongyun Lee; Joon-Tae Song

2010-01-01

383

Trap Concentration Dependence on the Electrical Properties of Annealed Ultrathin Fluorinated Silicon Oxides  

Microsoft Academic Search

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 (Phit) of

Wai-Jyh Chang; Mau-Phon Houng; Yeong-Her Wang

2001-01-01

384

Precipitates formation and its impact on the structure of plasma-deposited fluorinated silicon oxide films  

Microsoft Academic Search

Fluorine-doped silicon oxide (SiOF) films prepared by plasma enhanced chemical vapor deposition would generate precipitates on the film surface during exposure to air. The chemical and structural changes of SiOF films during the precipitation process were investigated under various fluorine-doping concentrations in SiOF films. Film composition depth profiles characterized by secondary ion mass spectrometer (SIMS) indicate uneven fluorine distribution within

Jun Wu; Ying-Lang Wang; Cheng-Tzu Kuo

2006-01-01

385

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

Microsoft Academic Search

Optical properties of fluorinated silicon oxide (SiOF) films for optical waveguide in optoelectronic devices were investigated. The SiOF films are formed at 25C 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

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

1998-01-01

386

Effect of deposition temperature on the bonding configurations and properties of fluorine doped silicon oxide film  

Microsoft Academic Search

In our study, fluorine-doped silicon oxide (SiOF) films were prepared using a mixture of SiH4, N2O, and CF4 in a conventional plasma enhanced chemical vapor deposition system at various deposition temperatures. Deposition behaviors are determined by the deposition temperature. Our results show that for temperatures below 300C the process is surface-reaction-limited controlled, but becomes diffusion-limited when the deposition temperature exceeds

Wei-Lun Lu; Ting-Wei Kuo; Chun-Hsien Huang; Na-Fu Wang; Yu-Zen Tsai; Ming-Wei Wang; Chen-I. Hung; Mau-Phon Houng

2011-01-01

387

Heavy-ion induced adhesion of thin gold films to oxidized substrates of tantalum and silicon  

Microsoft Academic Search

Energetic heavy ion beams are capable of enhancing the adhesion of metallic films to a variety of substrates. Gold films (200-600 ) evaporated onto substrates of tantalum and silicon (with native oxides) were bombarded with ions of 12C, 16O, 28Si, 35Cl and 58Ni at 2.85 MeV\\/nucleon. The threshold dose required to produce a peel strength greater than the Scotch-tape peel

R. G. Stokstad; P. M. Jacobs; I. Tserruya; L. Sapir; G. Mamane

1986-01-01

388

High-performance planar inductor on thick oxidized porous silicon (OPS) substrate  

Microsoft Academic Search

To obtain a high-performance planar inductor, we used the oxidized porous silicon (OPS) layer with 25-?m-thick SiO2 as substrate. The measured radio frequency (RP) performances of the planar Inductor on the OPS layer are comparable to those on the semi-insulating GaAs substrate. For a 6.29 nH inductor, resonant frequency of 13.8 GHz and maximum quality factor (Q) of 13.3 are

Choong-Mo Nam; Young-Se Kwon

1997-01-01

389

Laser-microwave photoconductivity of thermally oxidized silicon wafers: Laser wavelength and power dependence  

Microsoft Academic Search

Laser-microwave photoconductivity measurements were performed on thermally oxidized silicon wafers. Using a 830 nm laser, an almost exponential decay profile and similar effective lifetime were observed for the range of laser powers (7.5-25 W) used while the decay profile using a 910 nm laser was found to be strongly dependent on the laser power used. The 910 nm laser gave

Y. L. Khong

1995-01-01

390

Thermal analysis of silicon carbide based micro hotplates for metal oxide gas sensors  

Microsoft Academic Search

This paper reports on the thermal analysis of a novel micro hotplate design for metal oxide gas sensors. The hotplate is a 500?m500?m square shaped membrane made of 2?m thick polycrystalline 3CSiC on a silicon substrate suspended by four legs. The membrane is heated by an on chip platinum thin film heater. For reasons of a short response time and

G. Wiche; A. Berns; H. Steffes; E. Obermeier

2005-01-01

391

The Application of Strained-Silicon Germanium Heterostructures to Metal-Oxide Field-Effect Transistors  

Microsoft Academic Search

The metal-oxide-semiconductor field-effect transistor (MOSFET) is currently the device of choice for state-of -the-art digital electronics. Advanced silicon (Si) processing technology has allowed MOSFETs to be scaled to sub-micron dimensions, realizing incredible gains in performance and integration. However, certain physical constraints are being reached that limit continued scaling and the expected performance improvements. Hence, it is important to look for

Jeffrey John Welser

1995-01-01

392

A quantitative investigation of hydrogen in the metal-oxide-silicon system using NRA  

Microsoft Academic Search

The present state of development in the application of resonant nuclear reaction analysis to the direct measurement of hydrogen concentration profiles throughout the metal-oxide-silicon system is presented. Detection limits of less than 1018 cm-3 (1012 cm-2) as well as a depth resolution of better than 10 nm are obtained. Limitations of the technique in the study of changes in the

Michael A. Briere; Dietrich Braeunig; Braunig

1990-01-01

393

Hydrothermal synthesis map of bismuth titanates  

SciTech Connect

The hydrothermal synthesis of four bismuth titanate materials from common bismuth and titanium precursors under hydrothermal conditions is described. Reaction of NaBiO{sub 3}{center_dot}2H{sub 2}O and anatase TiO{sub 2} in concentrated NaOH solution at 240 Degree-Sign C is shown to produce perovskite and sillenite phases Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} and Bi{sub 12}TiO{sub 20}, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi{sub 1.43}Ti{sub 2}O{sub 6}(OH){sub 0.29}(H{sub 2}O){sub 0.66} is formed. The use of a mixture of HNO{sub 3} and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi{sub 4}Ti{sub 3}O{sub 12}. The phases have been isolated separately as phase-pure powders and profile refinement of powder X-ray diffraction data allows comparisons with comparable materials reported in the literature. Analysis of Bi L{sub III}-edge X-ray absorption near edge structure (XANES) spectra of the materials shows the oxidation state of bismuth is +3 in all of the hydrothermally derived products. - Graphical abstract: Use of NaBiO{sub 3}{center_dot}2H{sub 2}O and TiO{sub 2} as reagents under hydrothermal conditions allows the phase-pure preparation of four crystalline bismuth titanate materials. Highlights: Black-Right-Pointing-Pointer NaBiO{sub 3} and TiO{sub 2} under hydrothermal conditions allow formation of bismuth titanates. Black-Right-Pointing-Pointer Synthesis of four distint phases has been mapped. Black-Right-Pointing-Pointer Bi LIII-edge XANES shows Bi is reduced to oxidation state +3 in all materials. Black-Right-Pointing-Pointer A new hydrated bismuth titanate pyrochlore has been isolated.

Sardar, Kripasindhu [Department of Chemistry, University of Warwick, Coventry, CV4 7AL (United Kingdom); Walton, Richard I., E-mail: r.i.walton@warwick.ac.uk [Department of Chemistry, University of Warwick, Coventry, CV4 7AL (United Kingdom)

2012-05-15

394

Room-temperature formation of low refractive index silicon oxide films using atmospheric-pressure plasma.  

PubMed

This study aims to apply atmospheric-pressure (AP) plasma to the fabrication of single-layer anti-reflection (AR) coatings with porous silicon oxide. 150 MHz very high-frequency (VHF) excitation of AP plasma permits to enhance the chemical reactions both in the gas phase and on the film-growing surface, increasing deposition rate significantly. Silicon oxide films were prepared from silane (SiH4) and carbon dioxide (CO2) dual sources diluted with helium. The microstructure and refractive index of the films were studied using infrared absorption and ellipsometry as a function of VHF power density. It was shown that significant increase in deposition rate at room temperature prevented the formation of a dense SiO2 network, decreasing refractive index of the resulting film effectively. As a result, a porous silicon oxide film, which had the lowest refractive index of 1.24 at 632.8 nm, was obtained with a very high deposition rate of 235 nm/s. The reflectance and transmittance spectra showed that the low refractive index film functioned as a quarter-wave AR coating of a glass plate. PMID:21776642

Nakamura, Kei; Yamaguchi, Yoshihito; Yokoyama, Keiji; Higashida, Kosuke; Ohmi, Hiromasa; Kakiuchi, Hiroaki; Yasutake, Kiyoshi

2011-04-01

395

Silicon-based thin film solid oxide fuel cell array  

NASA Astrophysics Data System (ADS)

Solid oxide fuel cells (SOFC) have been known for their clean and efficient energy conversion. SOFCs utilize a range of ceramic electrolyte materials, with yttria stabilized zirconia (YSZ) as the most common choice. Traditional SOFCs operate at relatively high temperatures (800-1000C) due to their low oxide ion conductivity and high activation energy. Reducing the operating temperature is important to expand the field of SOFC applications, such as power sources for portable electronics. Reducing the electrolyte thickness by means of thin film deposition techniques to the submicrometer range is one way to reduce the Ohmic loss in SOFCs at lower temperature. In this paper, a miniature thin film fuel cell array is designed and fabricated targeting at reduced operating temperature as a potential portable power source.

Su, Pei-Chen; Prinz, Fritz B.

2010-03-01

396

Silicon nitride oxidation behaviour at 1000 and 1200 C  

Microsoft Academic Search

The oxidation behaviour of Si3N4Y2Si2O7 ceramics was investigated at 1000 and 1200C. These temperatures were chosen because most of the applications of Si3N4 occur at these temperatures. The Si3N4 samples were sintered by liquid phase sintering using 7 and 14vol.% of Y2Si2O7 as a sintering additive. The density of the sintered samples reached 99%. The samples were heated under stationary

Simone Pereira Taguchi; Sebastio Ribeiro

2004-01-01

397

Phase equilibria in the oxidation of impure silicon nitride  

Microsoft Academic Search

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

R. O. Williams; V. J. Tennery

1979-01-01

398

Topographic control on silicone surface using chemical oxidization method  

Microsoft Academic Search

The paper describes a wet process for modifying the surface of polydimethylsiloxane (PDMS) using H2SO4\\/HNO3 solutions. The oxidation on the surface of PDMS was confirmed by the examinations of Fourier transform infrared spectrometry (FTIR), contact angle of water drop and X-ray photoelectron spectroscopy (XPS). The hydrophobic surface of pristine PDMS was not only changed to hydrophilic, but also formed wrinkles

Teng-Kai Shih; Jeng-Rong Ho; Chia-Fu Chen; Wha-Tzong Whang; Chien-Chung Chen

2007-01-01

399

Influence of oxidizing ambient to tetraethylorthosilicate thin films containing solid-state reaction silicon nanocrystals  

NASA Astrophysics Data System (ADS)

In this work, we present a systematic study on the oxidation of solid-state reaction silicon nanocrystals (Si nc) embedded in tetraethylorthosilicate (TEOS) thin films. The 12.8 nm Si nc are spun coated in TEOS thin film and hard baked in O2 ambient at 900 C with varying times. The resulting grain size is investigated using x-ray diffraction and transmission electron microscopy. Si nanoclusters are observed. Upon 900 C oxidation with varying times, three main regions of grain size transition are identified. With short oxidation time, sintering with oxidation at the rim of the agglomerate dominates; at medium oxidation time, full sintering in the agglomerate with pure oxidation retarded by interfacial stress and strain dominates; at long oxidation time, self-limiting effect prevails. Study has been carried out using a combination of classical sintering model and Kao's two dimensional oxidation model considering the decrease of reaction rate with increasing stress perpendicular to the Si surface. In our developed model, the critical stress for self-limiting oxidation is found to be 2.9109 Pa.

Lau, H. W.; Tan, O. K.

2006-03-01

400

Breakdown voltage in silicon carbide metal-oxide-semiconductor devices induced by ion beams  

NASA Astrophysics Data System (ADS)

Metal-Oxide-Semiconductor (MOS) capacitors fabricated on 4H silicon carbide (SiC) were irradiated with heavy ions at energies of up to 454 MeV. The currents observed through the gate oxide of the MOS capacitors were monitored under biased conditions during ion irradiation. Under ion irradiation, the dielectric breakdown was observed at lower electric fields compared to the case under non-irradiation condition. The value of the electric field, at which the dielectric breakdown was obtained, decreased with increasing linear energy transfer (LET) of the incident ions.

Ohshima, T.; Deki, M.; Makino, T.; Iwamoto, N.; Onoda, S.; Hirao, T.; Kojima, K.; Tomita, T.; Matsuo, S.; Hashimoto, S.

2013-04-01

401

Oxidation bonding of porous silicon nitride ceramics with high strength and low dielectric constant  

Microsoft Academic Search

Silica (SiO2) bonded porous silicon nitride (Si3N4) ceramics were fabricated from ?-Si3N4 powder in air at 12001500C by the oxidation bonding process. Si3N4 particles are bonded by the oxidation-derive SiO2 and the pores derived from the stack of Si3N4 particles and the release of N2 and SiO gas during sintering. The influence of the sintering temperature and holding time on

Shuqiang Ding; Yu-Ping Zeng; Dongliang Jiang

2007-01-01

402

Comparison of beryllium oxide and pyrolytic graphite crucibles for boron doped silicon epitaxy  

SciTech Connect

This article reports on the comparison of beryllium oxide and pyrolytic graphite as crucible liners in a high-temperature effusion cell used for boron doping in silicon grown by molecular beam epitaxy. Secondary ion mass spectroscopy analysis indicates decomposition of the beryllium oxide liner, leading to significant incorporation of beryllium and oxygen in the grown films. The resulting films are of poor crystal quality with rough surfaces and broad x-ray diffraction peaks. Alternatively, the use of pyrolytic graphite crucible liners results in higher quality films.

Ali, Dyan; Richardson, Christopher J. K. [Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740 (United States)

2012-11-15

403

Strain-induced effects on the dielectric constant for thin, crystalline rare earth oxides on silicon  

NASA Astrophysics Data System (ADS)

Thin epitaxial rare earth oxide layers on Si exhibit K values that are much larger than the known bulk values. We investigate the thickness dependence of that enhancement effect for epitaxial Gd2O3 on Si(111). Controlling the oxide composition in ternary (Gd1-xNdx)2O3 thin films enables us to tune the lattice mismatch to silicon and thus the K values of the dielectric layer from 13 (close to the bulk value) up to 20. We show that simple tetragonal distortion of the cubic lattice is not sufficient to explain the enhancement in K. Therefore, we propose more severe strain induced structural phase deformations.

Schwendt, D.; Osten, H. J.; Shekhter, P.; Eizenberg, M.

2012-06-01

404

Oxidation of hydrogen doped tantalum films on silicon  

SciTech Connect

Hydrogen doping of Ta films before thermal oxidation affects the dc leakage current in oxidized Ta films. Metal-insulator-semiconductor (MIS) capacitors of Al/Ta/sub 2/O/sub 5/ (40 nm thick)/Si-substrate structures have been prepared for the electrical measurements. The Ta films were reactively sputtered on p-type Si substrates in a mixture of Ar and H/sub 2/ gases suitable for hydrogen doping. The hydrogen doping was found to be effective in reducing the leakage current in the Ta/sub 2/O/sub 5/ films to be less than 10/sup -3/ times that of undoped films, especially after low temperature oxidation at 400 /sup 0/C. Secondary ion mass spectrometry (SIMS) analysis showed that the incorporation in the Ta/sub 2/O/sub 5/ films of Si from the substrate was decreased by the presence of hydrogen during sputtering. A possible explanation for the reduction of leakage current caused by hydrogen doping is that the prevention of Si entry into Ta/sub 2/O/sub 5/ films reduces the density of oxygen vacancies induced by unsaturated SiO/sub x/(x<2). This is thought to suppress the Poole--Frenkel-type conduction in the Ta/sub 2/O/sub 5/ films.

Ohfuji, S.; Hashimoto, C.

1986-05-01

405

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

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

Xiaofan Meng; Anupama Bhat; Theodore Van Duzer

1999-01-01

406

Bismuth vanadate process  

SciTech Connect

This patent describes the process for the preparation of bismuth vanadate and bismuth vanadate-containing compounds wherein the precursor materials are calcined in the solid state at temperatures sufficient to react the precursor materials to prepare the vanadate compounds. It comprises: wet grinding the calcined product, contacting the calcined product with sufficient alkaline material to provide a pH level of 7.0-13.0 and recovering the treated product, the wet grinding of the calcined product being conducted either in the presence of the alkaline material or prior to the contacting with the alkaline material.

Sullivan, R.M.

1990-06-26

407

Epitaxial growth of zinc oxide thin films on silicon (100) substrates with zirconia buffer layer  

NASA Astrophysics Data System (ADS)

As an II-VI semiconductor, with wide bandgap and high exciton binding energy, zinc oxide has been favored for the new opto-electronic devices. One of the key issues for such applications is the integration of the zinc oxide onto silicon substrates. In this paper, we report a new integration methodology for depositing high quality zinc oxide thin films on silicon substrates. We have developed a novel epitaxial system for this purpose. An yttria stabilized zirconia (YSZ) buffer layer was used for depositing high quality, single crystalline zinc oxide films on Si (100) substrates. The heterostructure was developed with a pulsed laser deposition system. The results show that ZnO films grow epitaxially on YSZ buffered Si (100) substrates, with c-axis perpendicular to the substrate surface. High resolution image demonstrated that the interface between YSZ and ZnO is atomically smooth without any evidence of reaction. These zinc oxide films on Si (100), with YSZ buffer, showed excellent photoluminescence, evidenced with an extremely high exciton emission centered at 377 nm, at room temperature.

Aggarwal, Ravi; Jin, Chunming; Wei, Wei; Narayan, Jagdish; Narayan, Roger J.

2008-10-01

408

Bismuth glass holey fibers with high nonlinearity  

Microsoft Academic Search

We report on the progress of bismuth oxide glass holey fibers for nonlinear device applications. The use of micron-scale core diameters has resulted in a very high nonlinearity of 1100 W-1 km-1 at 1550 nm. The nonlinear performance of the fibers is evaluated in terms of a newly introduced figure-of-merit for nonlinear device applications. Anomalous dispersion at 1550 nm has

Heike Ebendorff-Heidepriem; P. Petropoulos; S. Asimakis; V. Finazzi; R. C. Moore; K. Frampton; F. Koizumi; D. J. Richardson; T. M. Monro

2004-01-01

409

Characterization of the mechanism of bi-layer oxide growth on austenitic stainless steels 316L and D9 in oxygen-controlled Lead-Bismuth Eutectic (LBE)  

Microsoft Academic Search

Lead Bismuth Eutectic (LBE) has been proposed for use in programs for accelerator-based and reactor-based transmutation of nuclear waste. LBE is a leading candidate material as a spallation target (in accelerator-based transmutation) and an option for the sub-critical blanket coolant. The corrosion by LBE of annealed and cold-rolled 316L stainless steels, and the modified austenitic stainless steel alloy D9, has

Daniel Koury

2008-01-01

410

Effect of neutron irradiation on passive oxidation of silicon carbide  

NASA Astrophysics Data System (ADS)

Hot-pressed SiC and pressureless-sintered SiC polycrystalline specimens were neutron-irradiated in the Japan Materials Testing Reactor up to 4.5 1024 n/m2 (E ? 1.0 MeV). The bulk specimens were crushed into powders to increase surface area. Weight change of the specimen and released CO2 gas content were measured after isothermal annealing between 500 and 1300C in oxidizing atmosphere using an electric balance and a gas chromatograph, respectively. There was no significant difference between irradiated and unirradiated specimens, for both hot-pressed and pressureless-sintered specimens. All of the weight gain data and amount of evolved CO2 satisfied a parabolic rate law against oxidation time. Apparent activation energy of the reaction confirmed the diffusion of O2 molecules through amorphous SiO2 layer. However, apparent activation energy decreased by the irradiation only in pressureless-sintered SiC containing B, suggesting the effect of transmuted atoms, or Li.

Yano, T.; Suzuki, M.; Miyazaki, H.; Iseki, T.

1996-10-01

411

CW bismuth fibre laser  

Microsoft Academic Search

A new fibre laser based on a bismuth-doped aluminosilicate glass fibre is proposed and fabricated. CW lasing is obtained in the spectral region between 1150 and 1300 nm. The fibres are fabricated by the method of modified chemical vapour deposition. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text

Evgenii M. Dianov; V. V. Dvoyrin; V. M. Mashinsky; A. A. Umnikov; M. V. Yashkov; A. N. Gur'yanov

2005-01-01

412

Gold nanoparticles on oxide-free silicon-molecule interface for single electron transport.  

PubMed

Two different organic monolayers were prepared on silicon Si(111) and modified for attaching gold nanoparticles. The molecules are covalently bound to silicon and form very ordered monolayers sometimes improperly called self-assembled monolayers (SAM). They are designed to be electrically insulating and to have very few electrical interface states. By positioning the tip of an STM above a nanoparticle, a double barrier tunnel junction (DBTJ) is created, and Coulomb blockade is demonstrated at 40 K. This is the first time Coulomb blockade is observed with an organic monolayer on oxide-free silicon. This work focuses on the fabrication and initial electrical characterization of this double barrier tunnel junction. The organic layers were prepared by thermal hydrosilylation of two different alkene molecules with either a long carbon chain (C11) or a shorter one (C7), and both were modified to be amine-terminated. FTIR and XPS measurements confirm that the Si(111) substrate remains unoxidized during the whole chemical process. Colloidal gold nanoparticles were prepared using two methods: either with citrate molecules (Turkevich method) or with ascorbic acid as the surfactant. In both cases AFM and STM images show a well-controlled deposition on the grafted organic monolayer. I-V curves obtained by scanning tunneling spectroscopy (STS) are presented on 8 nm diameter nanoparticles and exhibit the well-known Coulomb staircases at low temperature. The curves are discussed as a function of the organic layer thickness and silicon substrate doping. PMID:23488728

Caillard, Louis; Seitz, Oliver; Campbell, Philip M; Doherty, Rachel P; Lamic-Humblot, Anne-Flicie; Lacaze, Emmanuelle; Chabal, Yves J; Pluchery, Olivier

2013-04-09

413

Effect of controlled oxidation processes on the emission and excitation of porous silicon  

NASA Astrophysics Data System (ADS)

The strong luminescence activity of porous silicon prepared by anodization of silicon in HF is a remarkable phenomenon, considering the fact that ordinary crystalline silicon is not at all an efficient light emitter due to the indirect character of its bandgap. In spite of the intense theoretical and experimental activity, the basic mechanism responsible for this efficient luminescence is still under debate. Nevertheless, there is a growing concensus that quantum confinement in nanocrystallites is an important element of this mechanism. However, there are two competing models, both based on quantum confinement, namely bulk-like radiative recombination and novel radiative surface state recombination. In small crystallites the number of surface atoms is a sizeable fraction of the total and therefore surface conditions (both type and quality) are expected to play an important role. We have performed time-resolved emission in the musec regime and excitation measurements of porous silicon and studied the quantum efficiency under various surface oxidation treatments. We have found that, although the overall quantum efficiency (and hence the brightness of the porous surface) can vary a lot as a function of surface conditions, the time behavior of the luminescence is only weakly affected by these conditions. This leads to the conclusion that the emitting states are pretty much unaffected by the various surface treatments and consequently we believe that most likely one or both of the radiatively recombining carriers are localized.

Rigakis, Nikolaos

414

The effect of thermal oxidation on the luminescence properties of nanostructured silicon.  

PubMed

Herein is reported a detailed study of the luminescence properties of nanostructured Si using X-ray excited optical luminescence (XEOL) in combination with X-ray absorption near-edge structures (XANES). P-type Si nanowires synthesized via electroless chemical etching from Si wafers of different doping levels and porous Si synthesized using electrochemical method are examined under X-ray excitation across the Si K-, L(3,2) -, and O K-edges. It is found that while as-prepared Si nanostructures are weak light emitters, intense visible luminescence is observed from thermally oxidized Si nanowires and porous Si. The luminescence mechanism of Si upon oxidation is investigated by oxidizing nanostructured Si at different temperatures. Interestingly, the two luminescence bands observed show different response with the variation of absorption coefficient upon Si and O core-electron excitation in elemental silicon and silicon oxide. A correlation between luminescence properties and electronic structures is thus established. The implications of the finding are discussed in terms of the behavior of the oxygen deficient center (OCD) and non-bridging oxygen hole center (NBOHC). PMID:22549930

Liu, Lijia; Sham, Tsun-Kong

2012-05-02

415

The role of oxide interlayers in back reflector configurations for amorphous silicon solar cells  

NASA Astrophysics Data System (ADS)

Thin oxide interlayers are commonly added to the back reflector of thin-film silicon solar cells to increase their current. To gain more insight in the enhancement mechanism, we tested different back reflector designs consisting of aluminium-doped zinc oxide (ZnO:Al) and/or hydrogenated silicon oxide (SiOx:H) interlayers with different metals (silver, aluminium, and chromium) in standard p-i-n a-Si:H solar cells. We use a unique inverse modeling approach to show that in most back reflectors the internal metal reflectance is lower than expected theoretically. However, the metal reflectance is increased by the addition of an oxide interlayer. Our experiments demonstrate that SiOx:H forms an interesting alternative interlayer because unlike the more commonly used ZnO:Al it can be deposited by plasma-enhanced chemical vapour deposition and it does not reduce the fill factor. The largest efficiency enhancement is obtained with a double interlayer of SiOx:H and ZnO:Al.

Demontis, V.; Sanna, C.; Melskens, J.; Santbergen, R.; Smets, A. H. M.; Damiano, A.; Zeman, M.

2013-02-01

416

A novel ellipsometer for measuring thickness of oxide layer on the surface of silicon sphere  

NASA Astrophysics Data System (ADS)

The Avogadro constant NA is used as one of the several possible routes to redefinition of the kilogram in metrology today. Usually in order to accurately determine NA, the volume of a perfect single crystal silicon sphere of nearly 1 kg mass should be measured with a high relative uncertainty, i.e. about 110-8. However, the oxide layer grown on the surface of the silicon sphere causes a remarkable systematic difference between the measured and real diameters. A novel ellipsometer has been developed to determine the thickness of the oxide layer accurately and automatically. The arrangement of this instrument is suitable for measuring the layer on the sphere surface. What's more, the measuring is faster by optimizing the parameters and developing the algorithm of calculating the thickness and refractive index of the oxide layer. The preliminary simulation result has present. Thus, the uncertainty of the diameter measurement caused by the oxide layer can be observably reduced. And the further improving of this ellipsometer is discussed in the end.

Zhang, Jitao; Li, Yan

2008-03-01

417

Oxide-free hybrid silicon nanowires: From fundamentals to applied nanotechnology  

NASA Astrophysics Data System (ADS)

The ability to control physical properties of silicon nanowires (Si NWs) by designing their surface bonds is important for their applicability in devices in the areas of nano-electronics, nano-photonics, including photovoltaics and sensing. In principle a wealth of different molecules can be attached to the bare Si NW surface atoms to create e.g. Si-O, Si-C, Si-N, etc. to mention just the most prominent ones. Si-O bond formation, i.e. oxidation usually takes place automatically as soon as Si NWs are exposed to ambient conditions and this is undesired is since a defective oxide layer (i.e. native silicon dioxide - SiO2) can cause uncontrolled trap states in the band gap of silicon. Surface functionalization of Si NW surfaces with the aim to avoid oxidation can be carried out by permitting e.g. Si-C bond formation when alkyl chains are covalently attached to the Si NW surfaces by employing a versatile two-step chlorination/alkylation process that does not affect the original length and diameter of the NWs. Termination of Si NWs with alkyl molecules through covalent Si-C bonds can provide long term stability against oxidation of the Si NW surfaces. The alkyl chain length determines the molecular coverage of Si NW surfaces and thus the surface energy and next to simple Si-C bonds even bond types such as CC and CC can be realized. When integrating differently functionalized Si NWs in functional devices such as field effect transistors (FETs) and solar cells, the physical properties of the resultant devices vary.

Bashouti, Muhammad Y.; Sardashti, Kasra; Schmitt, Sebastian W.; Pietsch, Matthias; Ristein, Jrgen; Haick, Hossam; Christiansen, Silke H.

2013-02-01

418

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bismuth oxychloride. 73.1162 Section 73...CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically...

2013-04-01

419

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bismuth citrate. 73.2110 Section 73.2110...CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared...

2013-04-01

420

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Bismuth citrate. 73.2110 Section 73.2110...CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared...

2009-04-01

421

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Bismuth citrate. 73.2110 Section 73.2110...CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (c) * * * (1) The amount of bismuth citrate in the cosmetic shall not be in...

2010-04-01

422

21 CFR 73.2162 - Bismuth oxychloride.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Bismuth oxychloride. 73.2162 Section 73...CERTIFICATION Cosmetics § 73.2162 Bismuth oxychloride. (a) Identity and specifications. (1) The color additive bismuth oxychloride shall conform in...

2010-04-01

423

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Bismuth citrate. 73.2110 Section 73.2110...CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared...

2010-04-01

424

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Bismuth oxychloride. 73.1162 Section 73...CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically...

2010-04-01

425

21 CFR 73.2162 - Bismuth oxychloride.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bismuth oxychloride. 73.2162 Section 73...CERTIFICATION Cosmetics § 73.2162 Bismuth oxychloride. (a) Identity and specifications. (1) The color additive bismuth oxychloride shall conform in...

2013-04-01

426

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Bismuth oxychloride. 73.1162 Section 73...CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically...

2009-04-01

427

Quantitative comparison of the doubly integrated KLL Auger spectra of magnesium, aluminum, and silicon with their oxides  

SciTech Connect

Integrals, over selected electron energies, E, of magnesium, aluminum, and silicon KLL Auger spectra of magnesium, aluminum, silicon, and their oxides have been measured directly using tailored modulation techniques. The ratios of Auger currents, I(E), measured in this way from the metals and their respective oxides have been determined and are compared with the corresponding atomic densities of magnesium, aluminum, and silicon in the metals and their oxides. It has been found that, if the I(E) are measured over only the quasi-elastic KL/sub 2/ /sub 3/L/sub 2/ /sub 3/ Auger peaks, the ratios obtained agree quite well with the atomic densities, whereas, if the I(E) are measured over larger energy ranges, thereby encompassing peaks due to plasmon losses, the agreement is rather poor. This poor agreement is probably due to the quite different inelastic loss mechanisms that occur for the metals and their oxides.

Springer, R.W. (Air Force Materials Lab., Wright-Patterson Air Force Base, OH); Haas, T.W.; Grant, J.T.

1978-01-01

428

Preparation of a silicon heterojunction photodetector from colloidal indium oxide nanoparticles  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

429

Reduction of mosaic spread using iridium interlayers: A route to improved oxide heteroepitaxy on silicon  

NASA Astrophysics Data System (ADS)

Using epitaxial SrTiO3 and yttria-stabilized zirconia (YSZ) buffer layers deposited on silicon as a starting point, epitaxial iridium layers were grown by electron-beam evaporation using a two-step growth process with an extremely low initial deposition rate. The iridium layers had in-plane (twist) and out-of-plane (tilt) full widths at half maximum as narrow as 0.08 and 0.15, respectively, up to an order of magnitude narrower than the underlying SrTiO3 and YSZ layers. SrTiO3 and ZnO films grown on the iridium showed significantly narrower twist and tilt values than without the iridium interlayer, demonstrating a route to improved oxide heteroepitaxy on silicon.

Gsell, S.; Fischer, M.; Brescia, R.; Schreck, M.; Huber, P.; Bayer, F.; Stritzker, B.; Schlom, D. G.

2007-08-01

430

Isotopic labeling studies of interactions of nitric oxide and nitrous oxide with ultrathin oxynitride layers on silicon  

NASA Astrophysics Data System (ADS)

The interaction of nitric (NO) and nitrous (N2O) oxide with ultrathin (~1.5-3.5 nm) oxide and oxynitride films on silicon has been studied by performing high resolution depth profiling using medium energy ion scattering and isotopic labeling methods. We observe that, after NO annealing at 850 C, both O and N incorporate near the SiO2/Si interface. There is no nitrogen and little newly incorporated oxygen observed at the surface, implying that NO diffuses through the oxide film and dissociates and reacts at the interface. For N2O annealing, atomic oxygen resulting from decomposition of the gas can replace oxygen atoms in both oxide and oxynitride films. This replacement is most important at the surface, but also, to a smaller extent, occurs in the middle of the film. For ultrathin oxynitride films, oxide growth during reoxidation is faster in N2O than in pure O2. Atomic oxygen also influences the nitrogen distribution, which moves further into the film and accumulate at the new interface. We discuss the roles of atomic oxygen and peroxyl bridging oxygen species in explaining the observed phenomena.

Lu, H. C.; Gusev, E. P.; Garfunkel, E.; Busch, B. W.; Gustafsson, T.; Sorsch, T. W.; Green, M. L.

2000-02-01

431

Photoelectron spectroscopic studies of bismuth-excess strontium bismuth tantalate thin films and their high-pressure-O2annealing effects  

Microsoft Academic Search

The electronic structure of strontium bismuth tantalate (SBT) thin films has been studied by x-ray photoelectron spectroscopy and ultraviolet-ray photoyield spectroscopy (UV-PYS). The SBT films were prepared by metalorganic decomposition (MOD) method using a chemical solution of Sr:Bi:Ta=0.8:2.3:2. The XPS spectra imply that pyrochlore-dominant MOD-SBT films include bismuth oxides other than oxidized bismuth [(Bi2O2)2+] layers after high-pressure-O2 annealing. The UV-PYS

M. Takahashi; M. Noda; M. Okuyama

2003-01-01

432

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

NASA Astrophysics Data System (ADS)

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.

Stanca, Loredana; Petrache, Sorina Nicoleta; Serban, Andreea Iren; Staicu, Andrea Cristina; Sima, Cornelia; Munteanu, Maria Cristina; Z?rnescu, Otilia; Dinu, Diana; Dinischiotu, Anca

2013-05-01

433

Metal-oxide-high-k-oxide-silicon memory structure using an Yb2O3 charge trapping layer  

NASA Astrophysics Data System (ADS)

In this letter, we proposed a metal-oxide-high-k-oxide-silicon (MOHOS)-type memory structure using a high-k Yb2O3 charge trapping layer for flash memory applications. When using Fowler-Nordheim for charging and discharging, the high-k Yb2O3 MOHOS-type memories that had been annealed at 800 C exhibited large threshold voltage shifting (memory window of ~2.2 V) and excellent data retention (charge loss of ~6% measured time up to 104 s and at room temperature) because of the higher probability for trapping the charge carrier due to the formation of the Yb-silicate layer and the smooth surface roughness.

Pan, Tung-Ming; Chen, Jing-Wei

2008-11-01

434

Nitric oxide-generating silicone as a blood-contacting biomaterial  

PubMed Central

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.

Amoako, Kagya A.; Cook, Keith E.

2011-01-01

435

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

PubMed

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-?m 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, J(NO) (mol cm(-2) min(-1)), as measured by chemiluminescence, increased with surface Cu expression according to the relationship J(NO) = (1.63%SA(Cu) - 0.81) 10(-11), R(2) = 0.98, where %SA(Cu) 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 13 seconds with pure silicone and 339 44 seconds when 10 wt% Cu(II) was added. Scanning electron microscopies (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

Amoako, Kagya A; Cook, Keith E

436

Erbium-doped potassium bismuth gallate glasses  

NASA Astrophysics Data System (ADS)

We demonstrate potassium bismuth gallate glasses as suitable hosts for rare-earth-ion erbium (Er3+) operating in the 1.55-mum-wavelength region. The absorption and luminescence spectra along with the luminescence decay time were measured. The emission peak of the 4I13/2[right arrow]4I15/2 transition is at the 1.53-mum wavelength, and the spectral bandwidth is 85 nm, which is one of the broadest. The lifetime of the 4I13/2 level is approx2.42 ms, and the quantum efficiency is approx100%. The emission cross section is estimated to be approx12.4 x10-21 cm2, which is one of the highest among different oxide glasses. The gain coefficient is also calculated, and our results show that potassium bismuth gallate glasses are excellent host materials for broadband-amplifier and high-power-laser applications.

Man, S. Q.; Wong, S. F.; Pun, E. Y. B.

2002-08-01

437

High-aspect-ratio, silicon oxide-enclosed pillar structures in microfluidic liquid chromatography.  

PubMed

The present paper discusses the ability to separate chemical species using high-aspect-ratio, silicon oxide-enclosed pillar arrays. These miniaturized chromatographic systems require smaller sample volumes, experience less flow resistance, and generate superior separation efficiency over traditional packed bed liquid chromatographic columns, improvements controlled by the increased order and decreased pore size of the systems. In our distinctive fabrication sequence, plasma-enhanced chemical vapor deposition (PECVD) of silicon oxide is used to alter the surface and structural properties of the pillars for facile surface modification while improving the pillar mechanical stability and increasing surface area. The separation behavior of model compounds within our pillar systems indicated an unexpected hydrophobic-like separation mechanism. The effects of organic modifier, ionic concentration, and pressure-driven flow rate were studied. A decrease in the organic content of the mobile phase increased peak resolution while detrimentally effecting peak shape. A resolution of 4.7 (RSD = 3.7%) was obtained for nearly perfect Gaussian shaped peaks, exhibiting plate heights as low as 1.1 and 1.8 ?m for fluorescein and sulforhodamine B, respectively. Contact angle measurements and DART mass spectrometry analysis indicate that our employed elastomeric soft bonding technique modifies pillar properties, creating a fortuitous stationary phase. This discovery provides evidence supporting the ability to easily functionalize PECVD oxide surfaces by gas-phase reactions. PMID:21028836

Taylor, Lisa C; Lavrik, Nickolay V; Sepaniak, Michael J

2010-10-28

438

Band offsets of a ruthenium gate on ultrathin high-{kappa} oxide films on silicon  

SciTech Connect

Valence-band and conduction-band edges of ultrathin oxides (SiO{sub 2}, HfO{sub 2}, Hf{sub 0.7}Si{sub 0.3}O{sub 2}, and Al{sub 2}O{sub 3} grown on silicon) and their shifts upon sequential metallization with ruthenium have been measured using synchrotron-radiation-excited x-ray, ultraviolet, and inverse photoemissions. From these techniques, the offsets between the valence-band and conduction-band edges of the oxides, and the ruthenium metal gate Fermi edge have been directly measured. In addition the core levels of the oxides and the ruthenium have been characterized. Upon deposition, Ru remains metallic and no chemical alteration of the underlying oxide gates, or interfacial SiO{sub 2} in the case of the high-{kappa} thin films, can be detected. However a clear shift of the band edges is measured for all samples due to the creation of an interface dipole at the ruthenium-oxide interface. Using the energy gap, the electron affinity of the oxides, and the ruthenium work function that have been directly measured on these samples, the experimental band offsets are compared to those predicted by the induced gap states model.

Rangan, Sylvie; Bersch, Eric; Bartynski, Robert Allen; Garfunkel, Eric; Vescovo, Elio [Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States); Department of Chemistry and Chemical Biology and Laboratory for Surface Modification, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854 (United States); National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2009-02-15

439

Pull-test adhesion measurements of diamondlike carbon films on silicon carbide, silicon nitride, aluminum oxide, and zirconium oxide  

SciTech Connect

Hydrogenated amorphous carbon or diamondlike carbon (DLC) films were formed by 400 eV methane (CH[sub 4]) ion bombardment of various smooth and rough ceramics, as well as ceramics coated with a layer of Si or Ti. Adhesion was measured by a bonded-pin method. Excellent adhesion was measured for smooth SiC and Si[sub 3]N[sub 4], but adhesion of DLC to smooth Al[sub 2]O[sub 3] and ZrO[sub 2] was negligible. The use of a Si bonding interlayer produced good adhesion to all the substrates, but a Ti layer was ineffective due to poor bonding between the DLC film and Ti. Bulk thermodynamic calculations are not directly applicable to bonding at the interface because the interface is two dimensional and the compositions of interfacial phases are generally not known. If the standard enthalpy [Delta][ital H][degree] for the reaction between CH[sub 4] and the substrate material is calculated under the assumption that a carbide phase is produced, a relationship is seen between the reaction enthalpy and the relative adhesion. Large positive enthalpies are associated with poor adhesion; negative or small positive enthalpies are associated with good adhesion. This relation between enthalpy and adhesion was also observed for DLC deposited on Si. The lack of adhesion to the Ti was attributed to inadvertent formation of a surface oxide layer that rendered the enthalpy for the reaction with CH[sub 4] positive.

Erck, R.A.; Nichols, F.A. (Energy Technology Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Dierks, J.F. (North Dakota State University, Fargo, North Dakota 58105 (United States))

1994-07-01

440

Microcrystalline single and double junction silicon based solar cells entirely prepared by HWCVD on textured zinc oxide substrate  

Microsoft Academic Search

Microcrystalline silicon based single junction pin and amorphous-microcrystalline double junction pinpin solar cells were fabricated entirely by hot-wire chemical vapor deposition on textured zinc oxide substrates. The short circuit current density for microcrystalline pin cells shows an increase of 2025% compared to unetched zinc oxide, indicating a better light trapping on textured zinc oxide substrate. The best initial conversion efficiency

P. Kumar; M. Kupich; W. Bock; R. O. Dusane; B. Schroeder

2006-01-01

441

Active ingredient: Bismuth Subcitrate Potassium ...  

Center for Biologics Evaluation and Research (CBER)

Text VersionPage 1. Contains Nonbinding Recommendations Draft Guidance on Bismuth Subcitrate Potassium; Metronidazole; Tetracycline Hydrochloride ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

442

Coaxial nanocables of p-type zinc telluride nanowires sheathed with silicon oxide: synthesis, characterization and properties  

Microsoft Academic Search

Coaxial nanocables with a single-crystalline zinc telluride (ZnTe) nanowire core and an amorphous silicon oxide (SiOx) shell have been synthesized via a simple one-step chemical vapor deposition (CVD) method on gold-decorated silicon substrates. The single-crystal ZnTe nanowire core is in zinc-blende structure along the [111] direction, while the uniform SiOx shell fully covers the core with no observable pin-hole or

Y. L. Cao; Y. B. Tang; Y. Liu; Z. T. Liu; L. B. Luo; Z. B. He; J. S. Jie; Roy Vellaisamy; W. J. Zhang; C. S. Lee; S. T. Lee

2009-01-01

443

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

SciTech Connect

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.

Yokota, S.H.

1992-12-01

444

Complementary metal-oxide-semiconductor compatible high efficiency subwavelength grating couplers for silicon integrated photonics  

NASA Astrophysics Data System (ADS)

We demonstrate a through-etched grating coupler based on subwavelength nanostructure. The grating consists of arrays of 80 nm 343 nm rectangular air holes, which can be patterned in a single lithography/etch. A peak coupling efficiency of 59% at 1551.6 nm and a 3 dB bandwidth of 60 nm are achieved utilizing the silicon-on-insulator platform with a 1 ?m thick buried-oxide layer for transverse electric mode. The performance is comparable to gratings requiring much more complicated fabrication processes.

Xu, Xiaochuan; Subbaraman, Harish; Covey, John; Kwong, David; Hosseini, Amir; Chen, Ray T.

2012-07-01

445

Single hole transport in a silicon metal-oxide-semiconductor quantum dot  

NASA Astrophysics Data System (ADS)

We describe a planar silicon metal-oxide-semiconductor (MOS) based single hole transistor, which is compatible with conventional Si complementary MOS fabrication. A multi-layer gate design gives independent control of the carrier density in the dot and reservoirs. Clear Coulomb blockade oscillations are observed, and source-drain biasing measurements show that it is possible to deplete the dot down to the few hole regime, with excited states clearly visible. The architecture is sufficiently versatile that a second hole dot could be induced adjacent to the first one.

Li, R.; Hudson, F. E.; Dzurak, A. S.; Hamilton, A. R.

2013-10-01

446

Chemical Etching of Zinc Oxide for Thin-Film Silicon Solar Cells  

PubMed Central

Abstract Chemical etching is widely applied to texture the surface of sputter-deposited zinc oxide for light scattering in thin-film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and etching agent. All grain boundaries are prone to be etched to a certain threshold, that is defined by the deposition conditions and etching solution. Additionally, several approaches to modify the etching behavior through special preparation and etching steps are provided.

Hupkes, Jurgen; Owen, Jorj I; Pust, Sascha E; Bunte, Eerke

2012-01-01

447

Solar water splitting with a composite silicon\\/metal oxide semiconductor electrode  

Microsoft Academic Search

We have studied solar water splitting with a composite semiconductor electrode, composed of an n-i-p junction amorphous silicon (a-Si, Eg≈ 1.7 eV) layer, an indium tin oxide (ITO) layer, and a tungsten trioxide (WO3, Eg 2.8 eV) particulate layer. The n-i-p a-Si layer, which had more accurately a structure of n-type microcrystalline ( c) 3C-SiC:H (25 nm)\\/i-type a-Si:H (400 nm)\\/p-type

Yoshihiro Nakato; Naoaki Kato; Akihito Imanishi; Takashi Sugiura; Shunsuke Ogawa; Norimitsu Yoshida; Shuichi Nonomura

2006-01-01

448

Using nanopillars of silicon oxide as a versatile platform for visualizing a selective immunosorbent  

NASA Astrophysics Data System (ADS)

In this study, we fabricated nanopillar arrays of silicon oxide for use as two-dimensional periodic relief gratings (2DPRGs) on Si surfaces. We deposited antibodies onto the pillar surfaces of 2DPRGs modified with protein G to obtain optical detectors that were specific for the targeted antigen; the antigen units that filled the spaces between the nanopillars of the 2DPRG lead to a dramatic change in the pillar scale. The effective refractive index (neff) of the 2DPRGs was related to the pillar scale of the 2DPRG; after coupling of the antigen, a color change from pure green to orange was observable.

Chen, Jem-Kun; Zhou, Gang-Yan; Huang, Chih-Feng; Ko, Fu-Hsiang

2013-06-01

449

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

Microsoft Academic Search

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

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

2001-01-01

450

Self-Healing Breakdown Measurements of Pyrolytic Aluminum Oxide Films on Silicon  

Microsoft Academic Search

Self-healing breakdown techniques are employed to study dielectric breakdown in pyrolytic aluminum oxide films on silicon substrates. The Al2O3 is prepared by chemical vapor deposition at low temperature (300600C) using Al isopropoxide as source material. Both weak-spot breakdown and intrinsic breakdown in the absence of weak spots using Au&sngbnd;Al2O3&sngbnd;Si test capacitors are investigated. Intrinsic breakdown field strengths of 7.5106 V?cm

J. E. Carnes; M. T. Duffy

1971-01-01

451

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

SciTech Connect

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.

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

452

Low voltage resistive switching devices based on chemically produced silicon oxide  

NASA Astrophysics Data System (ADS)

We developed nonvolatile metal/SiOx/Si memristive devices based on ultrathin (~1 nm) silicon oxide that was produced in a Piranha solution. The devices exhibited repeatable resistive switching behavior with low programming voltages (as low as 0.5 V) and high ON/OFF conductance ratio. Devices with active metals as top electrodes were bipolar switches, while those with inert metal electrodes were unipolar. We also studied the switching mechanisms for both types of devices based on the filament formation and rupture, and proposed conduction models for Pt/SiOx/Si devices.

Li, Can; Jiang, Hao; Xia, Qiangfei

2013-08-01

453

Influence of molybdenum silicide additions on high-temperature oxidation resistance of silicon nitride materials  

SciTech Connect

The influence of additions of molybdenum disilicide (MoSi{sub 2}) on the microstructure and the mechanical properties of a silicon nitride (Si{sub 3}N{sub 4}) material, with neodymium oxide (Nd{sub 2}O{sub 3}) and aluminum nitride (AlN) as sintering aids, was studied. The composites, containing 5, 10, and 17.6 wt% MoSi{sub 2}, were fabricated by hot pressing. All materials exhibited a similar phase composition, detected by X-ray diffractometry. Up to MoSi{sub 2} additions of 10 wt%, mechanical properties such as strength, fracture toughness, or creep at 1,400 C were not affected significantly, in comparison to that of monolithic Si{sub 3}N{sub 4}. The oxidation resistance of the composites, in terms of weight gain, degraded. After 1,000 h of oxidation at 1,400 and 1,450 C in air, a greater weight gain (by a factor of approximately three) was obtained, in comparison to that of the material without MoSi{sub 2}. Nevertheless, after 1,000 h of oxidation, the degradation in strength of the composites was considerably less severe than that of the material without MoSi{sub 2}. An additional layer was formed, caused by processes at the surface of the Si{sub 3}N{sub 4} material, preventing the formation of pores, cracks, or glassy-phase-rich areas, which are common features of oxidation damage in Si{sub 3}N{sub 4} materials. This surface layer, containing Mo{sub 5}Si{sub 3} and silicon oxynitride (Si{sub 2}ON{sub 2}), was the result of reactions between MoSi{sub 2}, Si{sub 3}N{sub 4}, and the oxygen penetrating by diffusion into the material during the high-temperature treatment.

Klemm, H.; Tangermann, K.; Schubert, C.; Hermel, W. [Fraunhofer-Inst. Ceramic Technologies and Sintered Materials, Dresden (Germany)

1996-09-01