Note: This page contains sample records for the topic bismuth silicon oxide from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

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 µJ, 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 µJ range of firing energies and ignition response times of less than 2 µs 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

2

Electrooptic measurement of the volume resistivity of bismuth silicon oxide (Bi 12SiO 20)  

NASA Astrophysics Data System (ADS)

Single crystals of bismuth silicon oxide (Bi 12SiO 20) and its isomorphs (including, for example, bismuth germanium oxide (Bi 12GeO 20)) have been utilized in a wide range of active electrooptic and acoustoopic devices, including the Pockels Readout Optical Modulator (PROM), the PRIZ, the Photorefractive Incoherent-to-Coherent Optical Converter (PICOC), volume holographic storage devices, and surface acoustic wave devices. A key material parameter that influences device performance characteristics is the volume resistivity, which is difficult to measure accurately using standard techniques in refractory oxides like Bi 12SiO 20 due to its large magnitude (typically 10 13? cm). We present here a technique for the measurement of such very high resistivities in electrooptic materials; this method utilizes the electrooptic modulation induced by a voltage placed across the (crystallographically oriented) sample as a probe of temporal voltage transients that are in turn directly related to the sample volume resistivity. In our experiments, a very weak optical probe is frequency modulated, phase detected, and employed at low duty cycle to avoid ambiguities due to photoconductive voltage decay. The technique is described in detail, and experimental results are presented on a number of undoped and doped samples of bismuth silicon oxide grown by the Czochralski technique.

Seery, David A.; Garrett, Mark H.; Tanguay, Armand R.

1987-11-01

3

Raman spectroscopy of bismuth silicon oxide single crystals grown by the Czochralski technique  

NASA Astrophysics Data System (ADS)

In this work, single crystals of bismuth silicon oxide (BSO; Bi12SiO20) have been grown by the Czochralski method. The growth conditions were studied. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. The structure of the Bi12SiO20 has been investigated by x-ray diffraction (XRD), and Raman and Fourier transform infrared spectroscopy (FTIR) spectroscopy. The results obtained are discussed and compared with the published data. The pale yellow Bi12SiO20 single crystals prepared were without cores. Using spectroscopic measurements 19 Raman and 5 IR modes were observed.

Lazarevi?, Z.; Kosti?, S.; Radojevi?, V.; Rom?evi?, M.; Gili?, M.; Petrovi?-Damjanovi?, M.; Rom?evi?, N.

2013-11-01

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

Opto-electric particle manipulation on a bismuth silicon oxide crystal  

NASA Astrophysics Data System (ADS)

High-throughput manipulation of microparticles can be efficiently accomplished using electrokinetic effects. In this contribution, we demonstrate the two-dimensional investigation of internal space-charge fields inside a bismuth silicon oxide (BSO) crystal and their use for optically mediated particle trapping. The magnitude of the internal fields as well as the time constant for its build-up are measured by Zernike phase contrast and digital holography. The fast response time of a BSO crystal at very low light powers enables real-time generation of high electric field gradients. We demonstrate that this photoconductive material facilitates both electrophoretic and dielectrophoretic trapping of particles on an accessible surface.

Esseling, Michael; Glasener, Stefan; Volonteri, Federico; Denz, Cornelia

2012-04-01

6

Dynamic spatial structure of spontaneous beams in photorefractive bismuth silicon oxide  

NASA Astrophysics Data System (ADS)

We report the domain structure of spontaneously occurring beams (subharmonics) in photorefractive bismuth silicon oxide with an applied electric field from 1 to 6 kV/cm and a running grating. The subharmonic beams are generated in a pattern of domains that evolve dynamically as they move through the crystal. We find that the domains move as a whole with a speed approximately equal to that of the primary grating, but in the opposite direction. The domains are separated by narrow boundary regions, where the phase of the subharmonic waves changes by pi . The domain motion is consistent with the group velocity for running space-charge waves. .

Buchhave, Preben; Lyuksyutov, Sergei; Vasnetsov, Mikhail; Heyde, Carsten

1996-11-01

7

Effects of optical bias on moving gratings in bismuth silicon oxide at large fringe modulation  

NASA Astrophysics Data System (ADS)

Optical bias has been applied in the formation of moving gratings in bismuth silicon oxide at large fringe modulations. It is shown that optical bias is an effective method of overcoming the problems associated with the sudden drop in the optimum fringe velocity when the fringe modulation is close to unity. It is experimentally found that within a certain range of optical bias the absolute diffraction efficiency can be higher than that without optical bias, which is not the case when a stationary grating is used.

Wang, Z. Q.; Cartwright, C. M.; Gillespie, W. A.; Cook, N. J.

1996-07-01

8

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. Näfe; F. Aldinger

1999-01-01

9

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

10

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

11

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

12

Radiopacity and histological assessment of Portland cement plus bismuth oxide  

Microsoft Academic Search

Objective. The present study evaluated the subcutaneous connective tissue reactions and the radiopacity of MTA, Portland cement (PC), and Portland cement plus bismuth oxide (BO). Study design. Forty rats were divided into 5 groups (n 8 per group): A1: Control (empty capsule); A2: Pro-Root MTA; A3: PC; A4: PC BO 1:1; and A5: PC BO 2:1. Polyethylene tubes were filled

Tauby Coutinho-Filho; Leila Klein; Gisele Manera; Eduardo Diogo; RIO DE JANEIRO

13

Bismuth oxide nanotubes-graphene fiber-based flexible supercapacitors.  

PubMed

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

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

2014-07-10

14

Barium bismuth oxides with ?-, ?-, and ?-Bi 2 O 3 structures  

Microsoft Academic Search

Three new barium bismuth oxides have been synthesized containing 2.15–2.72 mol % BaO with the integer composition BaBi39O59.5, BaBi46O70, and BaBi40O61 and a monoclinic, cubic, and triclinic structure, respectively. These double oxides are, likely, derivatives of ?-, ?-, and\\u000a ?-Bi2O3 phases. The effects of the crucible material and surrounding atmosphere on the course of the synthesis of these new barium

L. A. Klinkova; V. I. Nikolaichik; N. V. Barkovskii; V. K. Fedotov

2007-01-01

15

Bismuth Oxide Nanoparticles in the Stratosphere  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

16

Tributylphosphate extraction behavior of bismuthate-oxidized americium.  

PubMed

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 Am (3+) in acidic solution. Room-temperature oxidation produced AmO 2 (2+) quantitatively, whereas oxidation at 80 degrees C produced AmO 2 (+) 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 Am (3+) at 503 nm, AmO 2 (+) at 514 nm, and AmO 2 (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 AmO 2 (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. PMID:18597416

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

2008-08-01

17

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

18

Silicon oxidation in fluoride solutions  

NASA Technical Reports Server (NTRS)

Silicon is produced in a NaF, Na2SiF6, and Na matrix when SiF4 is reduced by metallic sodium. Hydrogen is evolved during acid leaching to separate the silicon from the accompanying reaction products, NaF and Na2SiF6. The hydrogen evolution reaction was studied under conditions simulating leaching conditions by making suspensions of the dry silicon powder in aqueous fluoride solutions. The mechanism for the hydrogen evolution is discussed in terms of spontaneous oxidation of silicon resulting from the cooperative effects of (1) elemental sodium in the silicon that reacts with water to remove a protective silica layer, leaving clean reactive silicon, and (2) fluoride in solution that complexes with the oxidized silicon in solution and retards formation of a protective hydrous oxide gel.

Sancier, K. M.; Kapur, V.

1980-01-01

19

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

20

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

PubMed

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

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

2013-01-01

21

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

22

Transmission electron microscopy investigation of the crystal-amorphous-polycrystal transition in silicon during bismuth room temperature ion implantation  

Microsoft Academic Search

Transmission electron microscopy and related diffraction techniques are applied to characterize the structural modifications induced in a (1 0 0) silicon substrate by a bismuth ion implantation at room temperature. Calculations were performed to provide a theoretical support to the observations. It is shown that a 50 keV?10 ?A cm?2 Bi+ implantation successively induces: a complete silicon substrate amorphization —

J. Fauré; Ch. Angelov; M. Kalitzova; S. Simov

1997-01-01

23

Multifunctional multilayer films containing polyoxometalates and bismuth oxide nanoparticles.  

PubMed

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

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

2009-06-11

24

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

25

Formation of Bismuth Strontium Calcium Copper Oxide Superconducting Films by Chemical Vapor Deposition  

Microsoft Academic Search

Superconducting films of bismuth strontium calcium copper oxides were prepared by chemical vapor deposition at 910°C and 1 Torr on MgO substrate using a bismuth alkoxide and beta-diketonate chelates of Sr, Ca and Cu as source materials. In the film with Tc(zero) of 78 K, the predominant phase was Bi2(Sr, Ca)3 Cu2Ox with the c-axis perpendicular to the substrate.

Hisanori Yamane; Hideyuki Kurosawa; Toshio Hirai; Hideo Iwasaki; Norio Kobayashi; Yoshio Muto

1988-01-01

26

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 Bi 4Ta 2O 11, Bi 7Ta 3O 18 and Bi 3TaO 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 Cpm =445.8+0.005451 T-7.489×10 6/ T2 J K -1 mol -1, Cpm =699.0+0.05276 T-9.956×10 6/ T2 J K -1 mol -1 and Cpm =251.6+0.06705 T-3.237×10 6/ T2 J K -1 mol -1 for Bi 3TaO 7, Bi 4Ta 2O 11 and for Bi 7Ta 3O 18, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S° m(298.15 K)=449.6±2.3 J K -1 mol -1 for Bi 4Ta 2O 11, S° m(298.15 K)=743.0±3.8 J K -1 mol -1 for Bi 7Ta 3O 18 and S° m(298.15 K)=304.3±1.6 J K -1 mol -1 for Bi 3TaO 7, were evaluated from the low-temperature heat capacity measurements.

Leitner, J.; Jakeš, V.; Sofer, Z.; Sedmidubský, D.; R?ži?ka, K.; Svoboda, P.

2011-02-01

27

Redox-induced enhancement in interfacial capacitance of the titania nanotube/bismuth oxide composite electrode.  

PubMed

Bismuth oxide (Bi2O3) decorated titania nanotube array (T-NT) composite materials were synthesized by a simple, yet versatile electrodeposition method. The effects of deposition current density and time on morphology evolution of the bismuth oxide phase were analyzed. It was found that an optimum deposition condition in terms of current density and time could be reached to achieve uniform and equiaxed crystal morphology of the deposited oxide phase. The morphology, shape, size distribution, and crystal structure of the bismuth oxide phase were evaluated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic techniques. The electrochemical capacitance of the T-NT/Bi2O3 composites was studied by conducting cyclic voltammetry and galvanostatic charge-discharge experiments. These studies indicated that the capacitance behavior of the composite material was dependent on the morphology and distribution of the bismuth oxide phase. The capacitance was greatly enhanced for the composite having equiaxed and uniformly distributed bismuth oxide particles. The maximum interfacial capacitance achieved in this study was approximately 430 mF cm(-2). Galvanostatic charge-discharge experiments conducted on the composite materials suggested stable capacitance behavior together with excellent capacitance retention even after 500 cycles of continuous charge-discharge operation. PMID:23414084

Sarma, Biplab; Jurovitzki, Abraham L; Smith, York R; Mohanty, Swomitra K; Misra, Mano

2013-03-13

28

Structure, defects, and strain in silicon-silicon oxide interfaces  

NASA Astrophysics Data System (ADS)

The structure of the interfaces between silicon and silicon-oxide is responsible for proper functioning of MOSFET devices while defects in the interface can deteriorate this function and lead to their failure. In this paper we modeled this interface and characterized its defects and strain. MD simulations were used for reconstructing interfaces into a thermodynamically stable configuration. In all modeled interfaces, defects were found in the form of three-coordinated silicon atom, five coordinated silicon atom, threefold-coordinated oxygen atom, or displaced oxygen atom. Three-coordinated oxygen atom can be created if dangling bonds on silicon are close enough. The structure and stability of three-coordinated silicon atoms (Pb defect) depend on the charge as well as on the electric field across the interface. The negatively charged Pb defect is the most stable one, but the electric field resulting from the interface reduces that stability. Interfaces with large differences in periodic constants of silicon and silicon oxide can be stabilized by buckling of silicon layer. The mechanical stress resulted from the interface between silicon and silicon oxide is greater in the silicon oxide layer. Ab initio modeling of clusters representing silicon and silicon oxide shows about three time larger susceptibility to strain in silicon oxide than in silicon if exposed to the same deformation.

Kova?evi?, Goran; Pivac, Branko

2014-01-01

29

Schottky barrier heights of tantalum oxide, barium strontium titanate, lead titanate, and strontium bismuth tantalate  

Microsoft Academic Search

The Schottky barrier heights of various metals on the high permitivity oxides tantalum pentoxide, barium strontium titanate, lead zirconate titanate, and strontium bismuth tantalate have been calculated as a function of the metal work function. It is found that these oxides have a dimensionless Schottky barrier pinning factor S of 0.28-0.4 and not close to 1 because S is controlled

J. Robertson; C. W. Chen

1999-01-01

30

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

31

A new study on bismuth doped oxide glasses.  

PubMed

Spectroscopic properties of bismuth doped borate, silicate and phosphate glasses have been reinvestigated in this work. It shows the typical decay time of Bi(3+) is around 500ns rather than 2.7-to-3.9 ?s reported by Parke and Webb at room temperature. Introduction of higher content either alkali or alkali earth into borate glasses favors the Bi(3+) emission. As the contents increase excitation peak shifts regularly red while emission peak shows reverse trend. This, as revealed by Huang-Rhys factor, is due to the weakening of coupling between bismuth and glass host, and it can be interpreted within the frame of configurational coordinate diagrams. Differently, as bismuth concentration increases, both the excitation and emission shift red. The unknown origin of red emission from bismuth doped calcium or magnesium phosphate glass has been identified as Bi(2+) species on the basis of excitation spectrum and emission lifetime particularly after comparing with Bi(2+) doped materials. No near infrared (NIR) emission can be detected in these glasses within instrument limit. PMID:22772261

Xu, Wenbin; Peng, Mingying; Ma, Zhijun; Dong, Guoping; Qiu, Jianrong

2012-07-01

32

Reduction of thermal conductivity of bulk nanostructured bismuth telluride composites embedded with silicon nano-inclusions  

NASA Astrophysics Data System (ADS)

Bulk nanostructured bismuth telluride (Bi2Te3) composite with silicon nano-crystallite inclusions was synthesized via sintering approach. The effect of the composite structure formed by the addition of miniscule quantity (5 at. %) of silicon on the thermoelectric properties of bulk nanostructured Bi2Te3 is shown via a 50% drop in thermal conductivity accompanied with a simultaneous enhancement in the Seebeck coefficient. We demonstrate that the addition of silicon nano-inclusions to the nanostructured compound combined with a systematic thermal treatment beneficially reduces the thermal conductivity to less than 1.0 W/mK over the entire temperature range of 300 K to 525 K. It is shown that the combinatorial techniques of nanostructuring, nano-inclusions, and annealing are effective in reducing thermal conductivity by a significant magnitude. This low thermal conductivity is comparable to that of Bi2Te3 based superlattices and significantly lower than that of bulk Bi2Te3. The technique is extendable to (Bi,Se)2(Sb,Te)3 based thermoelectric alloys for enhancing the figure-of-merit.

Satyala, Nikhil; Tahmasbi Rad, Armin; Zamanipour, Zahra; Norouzzadeh, Payam; Krasinski, Jerzy S.; Tayebi, Lobat; Vashaee, Daryoosh

2014-01-01

33

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

2013-01-01

34

New Approach to Chemically Induced Silicon Oxidation.  

National Technical Information Service (NTIS)

The project New Approach to Chemically Induced Silicon Oxidation suggested a new and different approach to oxidation by the addition of small concentrations of a fluorine compound to the oxidation strain. This novel approach was successfully carried out w...

D. R. Young R. J. Jaccodine

1991-01-01

35

Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode.  

PubMed

Metal oxides are generally very stable in aqueous solutions and cheap, but their photochemical activity is usually limited by poor charge carrier separation. Here we show that this problem can be solved by introducing a gradient dopant concentration in the metal oxide film, thereby creating a distributed n(+)-n homojunction. This concept is demonstrated with a low-cost, spray-deposited and non-porous tungsten-doped bismuth vanadate photoanode in which carrier-separation efficiencies of up to 80% are achieved. By combining this state-of-the-art photoanode with an earth-abundant cobalt phosphate water-oxidation catalyst and a double- or single-junction amorphous Si solar cell in a tandem configuration, stable short-circuit water-splitting photocurrents of ~4 and 3 mA cm(-2), respectively, are achieved under 1 sun illumination. The 4 mA cm(-2) photocurrent corresponds to a solar-to-hydrogen efficiency of 4.9%, which is the highest efficiency yet reported for a stand-alone water-splitting device based on a metal oxide photoanode. PMID:23893238

Abdi, Fatwa F; Han, Lihao; Smets, Arno H M; Zeman, Miro; Dam, Bernard; van de Krol, Roel

2013-01-01

36

Hyperfine clock transitions of bismuth donors in silicon detected by spin-dependent recombination  

NASA Astrophysics Data System (ADS)

Bismuth donors ion-implanted in 28Si and natSi are studied using magnetic resonance spectroscopy based on spin-dependent recombination. The hyperfine clock transition, at which the linewidth is significantly narrowed, is observed for the bismuth donors. The experimental results are modeled quantitatively by molecular orbital theory for a coupled pair consisting of a bismuth donor and a spin-dependent recombination readout center, including the effect of hyperfine and Zeeman interactions.

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

2014-04-01

37

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

38

Microwave studies of thermally oxidized vacuum evaporated bismuth thin films on alumina  

Microsoft Academic Search

The bismuth thin films of various thicknesses (100nm-550nm) were deposited on alumina substrate by vacuum evaporation technique. These films were thermally oxidized in air at three different temperatures (125°C, 150°C, and 175°C). The films were characterized by XRD and SEM. X-ray diffraction studies shows dominant square-Bi2O3 crystal structure. Surface morphology shows granular shaped particles of Bi2O3 on alumina substrate. Microwave

S. Patil; D. Kulkarni; V. Puri

2008-01-01

39

Simulation of wet oxidation of silicon based on the interfacial silicon emission model and comparison with dry oxidation  

Microsoft Academic Search

Silicon oxidation in wet ambients is simulated based on the interfacial silicon emission model and is compared with dry oxidation in terms of the silicon-atom emission. The silicon emission model enables the simulation of wet oxidation to be done using the oxidant self-diffusivity in the oxide with a single activation energy. The amount of silicon emission from the interface during

Masashi Uematsu; Hiroyuki Kageshima; Kenji Shiraishi

2001-01-01

40

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

41

Rapid thermal oxidation of silicon nanowires  

NASA Astrophysics Data System (ADS)

Oxidation kinetics of silicon nanowires (SiNWs) subjected to rapid thermal oxidation (RTO) at 900 °C and 1000 °C in dry oxygen for exposure times ranging from 1 to 7.5 min is reported. For 1 min, SiNWs exhibit an enhanced oxidation rate compared to planar silicon, but for longer exposures the oxidation rates of SiNWs and planar Si are similar. Compared to furnace oxidation of SiNWs, RTO provides faster average oxidation rates and a weaker dependence of oxide shell thickness on the NW diameter. Our results demonstrate that RTO is an efficient approach for controlled oxidation of SiNWs.

Krylyuk, Sergiy; Davydov, Albert V.; Levin, Igor; Motayed, Abhishek; Vaudin, Mark D.

2009-02-01

42

Silicon filaments in silicon oxide for next-generation photovoltaics.  

PubMed

Nanometer wide silicon filaments embedded in an amorphous silicon oxide matrix are grown at low temperatures over a large area. The optical and electrical properties of these mixed-phase nanomaterials can be tuned independently, allowing for advanced light management in high efficiency thin-film silicon solar cells and for band-gap tuning via quantum confinement in third-generation photovoltaics. PMID:22290779

Cuony, Peter; Alexander, Duncan T L; Perez-Wurfl, Ivan; Despeisse, Matthieu; Bugnon, Gregory; Boccard, Mathieu; Söderström, Thomas; Hessler-Wyser, Aïcha; Hébert, Cécile; Ballif, Christophe

2012-03-01

43

Oxidation of Silicon Electrochemically Etched Microchannels Arrays  

Microsoft Academic Search

Macroporous silicon technology is an important method to fabricate microchannels on silicon. The formation of insulator layer on the sidewall of the channels is necessary for electrical isolation or passivation of the surface. Oxidation is one of the preferred options. In this paper we investigate the effect of various oxidation processes on the smoothness of the sidewalls of the high

Junxu Wu; Lianwei Wang; Xiaoming Chen; Mingjie Zheng; Weili Liu; Zhitang Song; P. M. Sarro

2006-01-01

44

The photoluminescence in electrochemically oxidized porous silicon  

Microsoft Academic Search

Some oxidized porous silicon samples exhibit an amorphous phase with the approximate composition SiO1.6. The particular features of the photoluminescence spectra were tentatively ascribed to the contribution of the interface between silicon and the non-stoichiometric oxide

M. Popescu; V. Chumash; I. Cojocaru; S. Zamfira; V. K. Jain; A. Gupta

1995-01-01

45

Capacity and cycle-life of batteries using bismuth-bearing oxide  

NASA Astrophysics Data System (ADS)

An examination is made of the capacity performance of lead-acid positive electrodes which are prepared from bismuth (Bi)-bearing oxide. This oxide is produced from Pasminco VRLA Refined™ lead which contains 0.05 wt.% Bi. For comparison, benchmark tests are performed on electrodes made from oxide with virtually no bismuth (<0.005 wt.%). The change in capacity is investigated by means of a purpose-built `compression cell'. With this design, the positive active-material is constrained under the action of a desirable, constant force during charge-discharge cycling. In general, the capacity increases with the compressive force. Importantly, the use of Bi-bearing oxide yields higher initial capacity and then a significantly faster rise in capacity to the full value with subsequent cycling. Commercial VRLA batteries made with Bi-bearing oxide exhibit a lower rate of self-discharge than those fabricated with conventional factory oxide. In addition, Bi-bearing batteries provide good cycle-life under the International Electrotechnical Commission (IEC) test.

Lam, L. T.; Haigh, N. P.; Lim, O. V.; Rand, D. A. J.; Manders, J. E.

46

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

47

Oxidation of liquid ternary bismuth-based alloys  

NASA Astrophysics Data System (ADS)

The oxidation of liquid alloys Bi-Ag-Cu, Bi-Ag-Ge, Bi-Ag-Sn, Bi-Ag-Pb, Bi-Cu-Sn, Bi-Sn-Pb, and Bi-In-Pb in air is studied as a function of the alloy composition by high-temperature gravimetry. The compositions of the oxide layers that form on these alloys are determined.

Denisova, L. T.; Denisov, V. M.; Istomin, S. A.; Pastukhov, E. A.; Korchemkina, N. V.

2013-08-01

48

Retention Reliability Improvement of Silicon-Oxide-Nitride-Oxide-Silicon Nonvolatile Memory with N2O Oxidation Tunnel Oxide  

Microsoft Academic Search

The reliability characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) devices with different thin tunnel oxides are studied. The device with the tunnel oxynitride grown in pure N2O ambient at a high temperature has better performance, including better leakage current, programming speed, read-disturb, and retention characteristics, than that with a tunnel oxide layer grown by dry oxidation with N2 annealing treatment. Moreover, the properties

Jia-Lin Wu; Chin-Hsing Kao; Hua-Ching Chien; Tzung-Kuen Tsai; Chien-Wei Liao

2007-01-01

49

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

50

Production of 1,3Butadiene From C 4 Raffinate3 Through Oxidative Dehydrogenation of n Butene Over Bismuth Molybdate Catalysts  

Microsoft Academic Search

Recent progress on the bismuth molybdate catalysts for oxidative dehydrogenation of n-butene to 1,3-butadiene was reported in this review. A number of bismuth molybdate catalysts, including pure bismuth molybdates\\u000a (?-Bi2Mo3O12, ?-Bi2Mo2O9, and ?-Bi2MoO6) and multicomponent bismuth molybdates, were prepared by a co-precipitation method for use in the production of 1,3-butadiene\\u000a from C4 raffinate-3 through oxidative dehydrogenation of n-butene. It was

Ji Chul Jung; Howon Lee; In Kyu Song

2009-01-01

51

2R regenerator based on a 2-m-long highly nonlinear bismuth oxide fiber.  

PubMed

We report the use of a 2-m-long Bismuth Oxide fiber with an ultra-high nonlinearity of ~1100 W(-1)km(-1) in a simple 2R regeneration experiment based on self phase modulation and offset filtering. Numerical simulations and experimental results confirm the suitability of this kind of fiber for 2R regeneration. An improvement in receiver sensitivity of more than 5 dB at 10 Gb/s and 2 dB at 40 Gb/s is achieved. PMID:19516664

Parmigiani, Francesca; Asimakis, Symeon; Sugimoto, Naoki; Koizumi, Fumihito; Petropoulos, Periklis; Richardson, David J

2006-06-12

52

Si nanowires grown from silicon oxide  

Microsoft Academic Search

Bulk-quantity Si nanowires have been synthesized by thermal evaporation of a powder mixture of silicon and SiO2. Transmission electron microscopy showed that, at the initial nucleation stage, silicon monoxide vapor was generated from the powder mixture and condensed on the substrate. Si nanoparticles were precipitated and surrounded by shells of silicon oxide. The Si nanowire nucleus consisted of a polycrystalline

N. Wang; Y. H. Tang; Y. F. Zhang; C. S. Lee; I. Bello; S. T. Lee

1999-01-01

53

Pulse electron spin resonance investigation of bismuth-doped silicon: Relaxation and electron spin echo envelope modulation  

NASA Astrophysics Data System (ADS)

Donors in silicon represent good candidates for the realization of several innovative devices exploiting classical as well as quantum information processing functionalities. Although most of the current work in the field is focused on the technological donors (P, As), the more exotic Bi offers interesting properties due to its nuclear spin and electronic structure. We present a detailed pulsed electron paramagnetic resonance study of the spin-spin and spin-lattice relaxation rates along with a full angular analysis of electron spin echo envelope modulation (ESEEM) spectra in bismuth-doped silicon samples having two different donor concentrations. The measurements were performed up to 40 K. ESEEM spectra provide information on the donor wave function via the leading superhyperfine interactions between donor nuclei and nearby Si29 coordination shells. The assignment of the most intense contributions was made on the basis of the angular variation of ESEEM resonances and elementary considerations on the deep donor states.

Belli, M.; Fanciulli, M.; Abrosimov, N. V.

2011-06-01

54

Crystal growth of bismuth(V) oxides from hydroxide fluxes  

Microsoft Academic Search

The first example of a 2 H-perovskite related A3A?BiO6 oxide, (Sr2.59Ba0.41)NaBiO6, with two different divalent cations on the A site, was synthesized in a reactive, mixed strontium-, barium-, sodium-hydroxide flux. (Sr2.59Ba0.41)NaBiO6 crystallizes in the space group R3¯c, with a=9.9839(2)Å and c=11.8008(4)Å. Crystals of isostructural oxides, Sr3NaBiO6 and Sr3LiBiO6, were also obtained from reactive Sr(OH)2, NaOH and LiOH fluxes. Sr3NaBiO6 and

M. Bharathy; Hargobind S. Khalsa; Mark D. Smith; H.-C. zur Loye

2009-01-01

55

One-dimensional single-crystalline bismuth oxide micro/nanoribbons: morphology-controlled synthesis and luminescent properties.  

PubMed

Based on a facile vapor-phase transport method without any catalyst and template, one-dimensional single-crystalline bismuth oxide (Bi2O3) micro/nanoribbons were fabricated on silicon substrates in large quantities and morphology-controlled fabrication of Bi2O3 was achieved from a single precursor. The widths of Bi2O3 ribbons varied from 0.2 to 20 microm depending on the deposition temperatures. The thickness was in the range of 0.1-2 microm and the length reached several hundred micrometers and even millimeter range. The detailed composition and structural analysis confirmed the single-crystalline nature of alpha-Bi2O3 micro/nanoribbons with monoclinic structure. The photoluminescence spectrum of a single Bi2O3 ribbon showed a broadband emission from 450 to 750 nm in the visible region, consisting two peaks located at 589 and 697 nm which were primarily originated from the impurity ions and crystal defects. A self-catalyzed vapor-solid model was proposed to account for the growth mechanism of Bi2O3 ribbons with different morphologies. PMID:21121334

Ling, B; Sun, X W; Zhao, J L; Shen, Y Q; Dong, Z L; Sun, L D; Li, S F; Zhang, S

2010-12-01

56

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

PubMed

Bismuth is doped to lanthanum strontium ferrite to produce ferrite-based perovskites with a composition of La0.8-xBixSr0.2FeO3-? (0 ? x ? 0.8) as novel cathode material for intermediate-temperature solid oxide fuel cells. The perovskite properties including oxygen nonstoichiometry coefficient (?), average valence of Fe, sinterability, thermal expansion coefficient, electrical conductivity (?), oxygen chemical surface exchange coefficient (Kchem), and chemical diffusion coefficient (Dchem) are explored as a function of bismuth content. While ? decreases with x due to the reduced Fe(4+) content, Dchem and Kchem increase since the oxygen vacancy concentration is increased by Bi doping. Consequently, the electrochemical performance is substantially improved and the interfacial polarization resistance is reduced from 1.0 to 0.10 ? cm(2) at 700 °C with Bi doping. The perovskite with x = 0.4 is suggested as the most promising composition as solid oxide fuel cell cathode material since it has demonstrated high electrical conductivity and low interfacial polarization resistance. PMID:24971668

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

2014-07-23

57

Oxidation of evaporated porous silicon rugate filters.  

PubMed

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 degrees C-650 degrees 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. PMID:17068573

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

2006-11-10

58

Characteristics of electrode overpotential over doped bismuth oxide solid electrolyte  

SciTech Connect

This paper reports the behavior of Ag, Pt, and La{sub 1 {minus} x}Sr{sub x}CoO{sub 3}(x = 0-0.7) electrodes over (Bi{sub 2}O{sub 3}){sub 1 {minus} y}(Er{sub 2}O{sub 3}){sub y}(y = 0.15, 0.2) studied by means of a current interruption method in the temperature range of 900- 1073 K and in the oxygen pressure range of 10-10{sup 5} Pa. An analysis model considering that the charge transfer process is affected by the mass-transfer process through the change of oxygen concentration was proposed and utilized for the analysis of electrode behavior. The electrode resistance of noble metals was approximately proportional to P{sub 0 2}{sup {minus} 1/2}, suggesting that the rate-determining step is the diffusion process of dissociatively adsorbed oxygen. The electrode resistance of Ag paste was dependent on the electric conductivity of the electrolyte. As for the oxide electrodes, the dependence of the resistance on the oxygen pressure was varied from -1/4th order at lower temperatures to -1/2th at higher temperatures. It was analyzed that both the charge transfer and diffusion processes are rate controlling, and that the degree of contribution of each process changes with temperature. The resistance due to the diffusion process decreased with Sr concentration. The simulation based on the proposed model agreed well with experimental results in the wide range of current density.

Nagamoto, H.; Inoue, H. (Univ. of Tokyo, Dept. of Chemical Engineering, Tokyo (JP))

1989-07-01

59

Effect of Oxygen Capacity and Oxygen Mobility of Pure Bismuth Molybdate and Multicomponent Bismuth Molybdate on their Catalytic Performance in the Oxidative Dehydrogenation of n Butene to 1,3Butadiene  

Microsoft Academic Search

Pure bismuth molybdate (?-Bi2MoO6) and multicomponent bismuth molybdate (Co9Fe3Bi1Mo12O51) catalysts were prepared by a co-precipitation method, and were applied to the oxidative dehydrogenation of n-butene to 1,3-butadiene. The Co9Fe3Bi1Mo12O51 catalyst showed a better catalytic performance than the ?-Bi2MoO6 catalyst in terms of conversion of n-butene and yield for 1,3-butadiene, indicating that the multicomponent bismuth molybdate was more efficient than the

Ji Chul Jung; Howon Lee; Heesoo Kim; Young-Min Chung; Tae Jin Kim; Seong Jun Lee; Seung-Hoon Oh; Yong Seung Kim; In Kyu Song

2008-01-01

60

Characterization of the aluminum-tantalum oxide-silicon dioxide-silicon charge storage (MTOS) device  

Microsoft Academic Search

A charge storage transistor is described which has several advantages as a non-volatile memory element over the MNOS (metal-silicon nitride-silicon dioxide-silicon) transistor. This device uses tantalum dioxide to replace silicon nitride as the second dielectric, resulting in an MTOS (metal-tantalum oxide-silicon dioxide-silicon) transistor. The obvious advantages of tantalum oxide are that its dielectric constant is larger than that of silicon

R. L. Angle; H. E. Talley

1975-01-01

61

Oxidation Resistance of Silicon Ceramics.  

National Technical Information Service (NTIS)

Oxidation resistance, and examples of oxidation of SiC, Si3N4 and sialon are reviewed. A description is given of the oxidation mechanism, including the oxidation product, oxidation reaction and the bubble size. The oxidation reactions are represented grap...

H. Yasutoshi K. Hirota

1984-01-01

62

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

63

Electrical conduction of silicon oxide containing silicon quantum dots  

Microsoft Academic Search

Current–voltage measurements have been made at room temperature on a Si-rich silicon oxide film deposited via electron-cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD) and annealed at 750–1000 C. The thickness of the oxide between Si quantum dots embedded in the film increases with increasing annealing temperature. This leads to a decreasing current density as the annealing temperature is increased.

X. D. Pi; O. H. Y. Zalloum; A. P. Knights; P. Mascher; P. J. Simpson

2006-01-01

64

Electrical conduction of silicon oxide containing silicon quantum dots  

Microsoft Academic Search

Current-voltage measurements have been made at room temperature on a Si-rich silicon oxide film deposited via electron-cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD) and annealed at 750-1000 °C. The thickness of the oxide between Si quantum dots embedded in the film increases with increasing annealing temperature. This leads to a decreasing current density as the annealing temperature is increased.

X. D. Pi; O. H. Y. Zalloum; A. P. Knights; P. Mascher; P. J. Simpson

2006-01-01

65

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

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

66

Phase equilibria of the bismuth oxide-calcium oxide-copper oxide system in oxygen at 1 atm  

SciTech Connect

Phase equilibria in the bismuth oxide-calcium oxide-copper oxide system have been determined at 1 atm pressure in oxygen over the temperature range of 750--1,000 C. The phases found to be stable at 750 C are Bi{sub 2}CuO{sub 4}, CuO, Ca{sub 2}CuO{sub 3}, CaO, Bi{sub 2}Ca{sub 2}O{sub 5}, Bi{sub 6}Ca{sub 4}O{sub 13}, Bi{sub 14}Ca{sub 5}O{sub 26}, a rhombohedral Bi-Ca oxide solid solution (Rh{sub ss}), and a face-centered cubic Bi-Ca oxide solid solution (Fcc{sub ss}) that includes Bi{sub 2}O{sub 3}. At 800 C, the stable phases are Bi{sub 2}CuO{sub 4}, CuO, Ca{sub 2}CuO{sub 3}, CaO, Bi{sub 2}Ca{sub 2}O{sub 5}, Bi{sub 6}Ca{sub 4}O{sub 13}, a hexagonal Bi-Ca oxide solid solution ({delta}{sub ss}), Rh{sub ss}, Fcc{sub ss}, and liquid. The phases found to be stable at 850 C are CuO, Ca{sub 2}CuO{sub 3}, CaO, Bi{sub 2}Ca{sub 2}O{sub 5}, Bi{sub 6}Ca{sub 4}O{sub 13}, Fcc{sub ss}, and liquid. The phases found to be stable at 900 C are CuO, Ca{sub 2}CuO{sub 3}, CaO, Bi{sub 2}Ca{sub 2}O{sub 5}, a body-centered cubic Bi-Ca oxide solid solution (Bcc{sub ss}), and liquid. The stable phases at 950 C are CuO, Ca{sub 2}CuO{sub 3}, CaO, and liquid. At 1,000 C, the stable phases are CuO, Ca{sub 3}Cu{sub 7}O{sub 10}, Ca{sub 2}CuO{sub 3}, CaO, and liquid.

Tsang, C.F.; Meen, J.K.; Elthon, D. [Univ. of Houston, TX (United States)

1997-06-01

67

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

68

Two-Dimensional Thermal Oxidation of Silicon. 1. Experiments.  

National Technical Information Service (NTIS)

This paper introduces a unique experimental approach in which extensive data were obtained concerning the oxidation of cylindrical silicon structures of controlled radii of curvature. It is quantitatively demonstrated that the oxidation of curved silicon ...

D. B. Kao J. P. McVittie W. D. Nix K. C. Saraswat

1979-01-01

69

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 ...

70

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

71

Silicon oxide colloidal/polymer nanocomposite films  

SciTech Connect

The quarter-wavelength ({lambda}/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50 MHz), the {lambda}/4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

Wang Haifeng; Cao Wenwu; Zhou, Q.F.; Shung, K. Kirk; Huang, Y.H. [Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Biomedical Engineering and NIH Transducer Resource Centre, University of Southern California, Los Angeles, California 90089 (United States); Chemat Technology Inc., Northridge, California 91324 (United States)

2004-12-13

72

A SIMPLE SILICON BASED NITRIC OXIDE SENSOR  

Microsoft Academic Search

Nitric oxide (NO) is known to mediate many beneficial physiology processes, motivating its detection in vivo as well as in vitro. Electrochemical detection provides the required cellular level determination of NO among several other techniques. In this work, electrochemical micro-sensors for both types of detection, in vivo and in vitro, were developed, exploring the silicon planar technology, which presents high

Rogerio Furlan; Koiti Arakai; Jorge J. Santiago-Aviles

73

Visible light photooxidative performance of a high-nuclearity molecular bismuth vanadium oxide cluster  

PubMed Central

Summary The visible light photooxidative performance of a new high-nuclearity molecular bismuth vanadium oxide cluster, H3[{Bi(dmso)3}4V13O40], is reported. Photocatalytic activity studies show faster reaction kinetics under anaerobic conditions, suggesting an oxygen-dependent quenching of the photoexcited cluster species. Further mechanistic analysis shows that the reaction proceeds via the intermediate formation of hydroxyl radicals which act as oxidant. Trapping experiments using ethanol as a hydroxyl radical scavenger show significantly decreased photocatalytic substrate oxidation in the presence of EtOH. Photocatalytic performance analyses using monochromatic visible light irradiation show that the quantum efficiency ? for indigo photooxidation is strongly dependent on the irradiation wavelength, with higher quantum efficiencies being observed at shorter wavelengths (?395nm ca. 15%). Recycling tests show that the compound can be employed as homogeneous photooxidation catalyst multiple times without loss of catalytic activity. High turnover numbers (TON ca. 1200) and turnover frequencies up to TOF ca. 3.44 min?1 are observed, illustrating the practical applicability of the cluster species.

Tucher, Johannes

2014-01-01

74

Effects of oxide formation around core circumference of silicon-on-oxidized-porous-silicon strip waveguides.  

PubMed

We have studied the effect of oxidation on the propagation loss and surface roughness of silicon-on-oxidized-porous-silicon strip waveguides fabricated using proton-beam irradiation and electrochemical etching. A thin thermal oxide is formed around the core of the waveguide, enabling the symmetric reduction of core size and roughness on all sides. Significant loss reduction from about 10 dB/cm to 1 dB/cm has been obtained in TE and TM polarizations after oxidation smoothening of both the bottom and the sidewalls by 20 nm. This corresponds well with simulations using the beam-propagation method that show significant contributions from both surfaces. PMID:19838253

Teo, E J; Xiong, B Q; Ow, Y S; Breese, M B H; Bettiol, A A

2009-10-15

75

Tailoring Silicon Oxycarbide Glasses for Oxidative Stability  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

76

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

77

Study on control of oxygen concentration in lead bismuth flow using lead oxide particles  

NASA Astrophysics Data System (ADS)

Performance of mass exchanger type oxygen control system for the control of oxygen concentration in a flowing lead-bismuth (Pb-Bi) was investigated in a low temperature region of a Pb-Bi circulation loop. Oxygen dissolved and diffused from lead oxide (PbO) particles into the melt or oxide precipitated in the mass exchanger. The electromotive force (EMF) of an oxygen sensor installed in a high temperature region of the loop indicated the changes of oxygen concentration in the loop with the temperature changes of the PbO particles reasonably. The measured EMF agreed well with theoretical result obtained using ?GPb-Bi-O equation 0 in the Nernst equation. The expression of oxygen solubility in the melt in the mass exchanger, Cs, was derived from the data as log Cs = A + B/ T, where the constant A ranged from -4000 to -4600, and the constant B ranged from 1 to 3.5 depending on the temperature of the melt.

Kondo, Masatoshi; Takahashi, Minoru; Miura, Kuniaki; Onizawa, Tatsuya

2006-10-01

78

Preparation of bismuth oxyiodides and oxides and their photooxidation characteristic under visible/UV light irradiation  

SciTech Connect

Bismuth oxyiodides and oxides were prepared by a solution combination with thermal treatment method. The prepared samples were characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectra, and Brunauer-Emmett-Teller surface areas. The photooxidation activity of the samples was evaluated by photocatalytic decolorization of acid orange II under both visible light ({lambda} > 420 nm) and UV light ({lambda} = 365 nm) irradiation. Results show that a series of changes in the compounds take place during the course of calcination, described as: BiOI {yields} Bi{sub 5}O{sub 7}I {yields} {alpha}-Bi{sub 2}O{sub 3}. Under visible light irradiation, the photocatalytic activities follow the order: BiOI > Bi{sub 5}O{sub 7}I > Bi{sub 5}O{sub 7}I/Bi{sub 2}O{sub 3} mixture > Bi{sub 2}O{sub 3}, which is mainly attributed to the different absorption ability to visible light due to the different band gap energy; the activities are in the order: BiOI < Bi{sub 2}O{sub 3} < Bi{sub 5}O{sub 7}I/Bi{sub 2}O{sub 3} mixture < Bi{sub 5}O{sub 7}I under UV light irradiation, which is mainly caused by the different oxidability.

Yu, Changlin, E-mail: yuchanglinjx@163.com [School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China)] [School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China); Fan, Caifeng [School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China)] [School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China); Yu, Jimmy C. [Department of Chemistry, The Center of Novel Functional Molecules, and Environmental Science Programme, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China)] [Department of Chemistry, The Center of Novel Functional Molecules, and Environmental Science Programme, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China); Zhou, Wanqin [School of Information Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China)] [School of Information Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China); Yang, Kai [School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China)] [School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, Jiangxi (China)

2011-01-15

79

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

80

Emission of visible light from porous silicon during anodic oxidation  

Microsoft Academic Search

The electrochemical oxidation of p-type porous silicon prepared under different conditions is investigated. During the oxidation process, bright visible light is emitted from the surface. The time evolution of integrated electroluminescence signals obtained from a silicon photodiode are shown. The signal duration and relative intensity as a function of process parameters during the formation of the porous silicon and during

Beatrys M. Lacquet; D. F. Malan

1994-01-01

81

Effect of silicon oxide, silicon nitride and polysilicon layers on the electrostatic pressure during anodic bonding  

Microsoft Academic Search

The quality of the anodic bonding between glass and silicon wafers coated with silicon oxide, silicon nitride and polysilicon layers has been investigated. We have used an electrostatic test to study the effect of these layers on the quality of the bond. The electrostatic test shows how the electrostatic pressure decreases with the increase of the thickness of the silicon

J. A. Plaza; J. Esteve; E. Lora-Tamayo

1998-01-01

82

Characteristics of Silica-on-Silicon Platform with Silicon Oxide Treatment for Hybrid Integrated Optical Module  

NASA Astrophysics Data System (ADS)

To investigate the effects of the silicon oxide process on the characteristics of the silica planar lightwave circuit (PLC) platform, we have compared two silicon oxide formation processes, thermal oxidation and plasma-enhanced chemical vapor deposition (PECVD). The thermal oxidation process for forming a silicon oxide layer on the silica platform generates surface defects and a crystobalite crystal phase, resulting in the deterioration of optical waveguide characteristics. However, the silica platform with a silicon oxide layer formed by PECVD has a transparent planar optical waveguide by suppressing the crystal growth of silica due to low processing temperatures.

Kim, Tae-Hong; Yoon, Ki-Hyun

2003-06-01

83

Determination of bismuth by electrochemical stripping analysis; elimination of interferences by using a mercury film electrode modified with tri-n-octylphosphine oxide, and application to copper alloys.  

PubMed

A mercury film electrode modified with a film consisting of tri-n-octylphosphinc oxide in a poly(vinyl chloride) matrix is used for a galvanostatic stripping determination of bismuth in copper and copper alloys. The method can be used to determine from 0.002 to 0.5% of bismuth. It is very selective, simple and rapid. The precision and accuracy are good and the only serious interference is caused by tin(IV). PMID:18964027

Lexa, J; Stulík, K

1986-01-01

84

Edge states and topological properties of electrons on the bismuth on silicon surface with giant spin-orbit coupling  

NASA Astrophysics Data System (ADS)

We derive a model of localized edge states in a finite-width strip for the two-dimensional electron gas formed in the hybrid system of a bismuth monolayer deposited on the silicon interface and described by the nearly free electron model with giant spin-orbit splitting. The edge states have the energy dispersion in the bulk energy gap with a Dirac-like linear dependence on the quasimomentum and the spin polarization coupled to the direction of propagation, demonstrating the properties of a topological insulator. The topological stability of edge states is confirmed by the calculations of the Z 2 invariant taken from the structure of the Pfaffian for the time reversal operator for the filled bulk bands in the surface Brillouin zone, which is shown to have a stable number of zeros with the variations of material parameters. The proposed properties of the edge states may support future advances in experimental and technological applications of this new material in nanoelectronics and spintronics.

Khomitsky, D. V.; Chubanov, A. A.

2014-03-01

85

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

86

Packet clock recovery using a bismuth oxide fiber-based optical power limiter.  

PubMed

We demonstrate an optical clock recovery circuit that extracts the line rate component on a per packet basis from short data packets at 40Gb/s. The circuit comprises a Fabry-Perot filter followed by a novel power limiting configuration, which in turn consists of a 5m highly nonlinear bismuth oxide fiber in cascade with an optical bandpass filter. Both experimental and simulation-based results are in close agreement and reveal that the proposed circuit acquires the timing information within only a small number of bits, yielding a packet clock for every respective data packet. Moreover, we investigate theoretically the scaling laws for the parameters of the circuit for operation beyond 40 Gb/s and present simulation results showing successful packet clock extraction for 160 Gb/s data packets. Finally, the circuit's potential for operation at 320 Gb/s is discussed, indicating that ultrafast packet clock recovery should be in principle feasible by exploiting the passive structure of the device and the fsec-scale nonlinear response of the optical fiber. PMID:19547344

Kouloumentas, Ch; Pleros, N; Zakynthinos, P; Petrantonakis, D; Apostolopoulos, D; Zouraraki, O; Tzanakaki, A; Avramopoulos, H; Tomkos, I

2007-08-01

87

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

2013-03-21

88

The study of optical band edge property of bismuth oxide nanowires ?-Bi2O3.  

PubMed

The ?-phase Bi(2)O(3) (?-Bi(2)O(3)) is a crucial and potential visiblelight photocatalyst material needless of intentional doping on accommodating band gap. The understanding on fundamental optical property of ?-Bi(2)O(3) is important for its extended applications. In this study, bismuth oxide nanowires with diameters from tens to hundreds nm have been grown by vapor transport method driven with vapor-liquid-solid mechanism on Si substrate. High-resolution transmission electron microscopy and Raman measurement confirm ? phase of monoclinic structure for the as-grown nanowires. The axial direction for the as-grown nanowires was along < 122 >. The band-edge structure of ?-Bi(2)O(3) has been probed experimentally by thermoreflectance (TR) spectroscopy. The direct band gap was determined accurately to be 2.91 eV at 300 K. Temperaturedependent TR measurements of 30-300 K were carried out to evaluate temperature-energy shift and line-width broadening effect for the band edge of ?-Bi(2)O(3) thin-film nanowires. Photoluminescence (PL) experiments at 30 and 300 K were carried out to identify band-edge emission as well as defect luminescence for the ?-Bi(2)O(3) nanowires. On the basis of experimental analyses of TR and PL, optical characteristics of direct band edge of ?-Bi(2)O(3) nanowires have thus been realized. PMID:23736418

Ho, Ching-Hwa; Chan, Ching-Hsiang; Huang, Ying-Sheng; Tien, Li-Chia; Chao, Liang-Chiun

2013-05-20

89

Charge storage properties of the metal tantalum oxide-silicon dioxide-silicon (MTOS)  

Microsoft Academic Search

The characteristics of tantalum oxide and the tantalum oxide\\/silicon dioxide system as they apply to charge storage devices were investigated. Both anodic and thermally grown Ta2O5 were studied. The conduction properties of both are shown to follow a Poole Frenkel mechanism. Capacitance voltage measurements show a negative Qss with values smaller than those in comparable metal-silicon nitride-silicon dioxide-silicon (MNOS) devices.

R. L. Angle

1976-01-01

90

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

91

Dry Pressure Local Oxidation of Silicon for IC Isolation.  

National Technical Information Service (NTIS)

This communication reports the use of dry pressure-oxidation (P-OX) for obtaining oxide-isolated device structures in both bulk silicon and epitaxial silicon on sapphire (SOS). Dry P-OX is a new low temperature oxidation technique which, compared with con...

S. Marshall R. J. Zeto C. G. Thornton

1975-01-01

92

Producing bismuth trioxide and its application in fire assaying  

NASA Astrophysics Data System (ADS)

Bismuth trioxide (Bi2O3) is the prevalent commercial oxide of bismuth. A precursor to the preparation of other compounds of bismuth, including the chemical reagents, bismuth trioxide has specialized uses in optical glass, flame-retardant paper, and, increasingly, in glaze formulations where it substitutes for lead oxides. In the last decade, bismuth trioxide has also become a key ingredient in flux formulations used by mineral analysts in fire assaying. The production of bismuth trioxide generally begins with the minor metal bismuth. This paper describes bismuth trioxide production and the properties and basis for its use in environmentally sound fire assaying.

Kelly, Zack; Ojebuoboh, Funsho

2002-04-01

93

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

94

Structural environments and oxidation states of metal cations in bismuth cerium molybdate solid solutions by x-ray spectroscopy  

SciTech Connect

Bismuth and cerium L/sub 3/-edge and molybdenum K-edge X-ray absorption investigations of silica-supported bismuth cerium molybdates were undertaken to probe the local structural environments and oxidation states of the metal cations. A total of 10 single-phase compositions in the bimodal Bi/sub 2-x/Ce/sub x/(MoO/sub 4/)/sub 3/ solid solution (for 0 less than or equal to x less than or equal to 0.25 and 1 less than or equal to x less than or equal to 1.5) were examined; namely, x = 0, 0.025, 0.075, 0.125, 0.2, 0.25, 1, 1.125, 1.25, and 1.5. For low cerium concentrations (x less than or equal to 0.25), the Bi/sub 2-x/Ce/sub x/(MeO/sub 4/)/sub 3/ materials possess severely distorted defect-scheelite structure with cerium cations dissolved in the Bi/sub 2/(MoO/sub 4/)/sub 3/ (x = 0) lattice, whereas for high cerium concentrations (x greater than or equal to 1), they possess undistorted defect-scheelite structures with bismuth cations dissolved in the Ce/sub 2/(MoO/sub 4/)/sub 3/ (x = 2) lattice. The EXAFS results provide the first quantitative structural information about the individual Bi/sup 3 +/ and Ce/sup 3 +/ sites in the Bi/sub 2-x/Ce/sub x/(MoO/sub 4/)/sub 3/ compositions for 0.025 less than or equal to x less than or equal to 1.5; only site-averaged metrical parameters for an admixture of bismuth and cerium cation positions are available from X-ray and neutron diffraction measurements.

Antonio, M.R.; Brazdil, J.F.; Glaeser, L.C.; Mehicic, M.; Teller, R.G.

1988-04-21

95

Composition, Chemical Structure and Electrical Properties of Thin Silicon Oxides Prepared by Oxidation of Silicon in Nitrous Oxide  

Microsoft Academic Search

In the continuing effort to scale down metal-oxide -semiconductor (MOS) devices, there is a need for high quality thin dielectrics. Growth of silicon oxides in nitrous oxide (N_2O) incorporates a small amount of nitrogen in the SiO_2 , and improves the electrical properties compared to conventional oxides grown in oxygen. This thesis describes correlations between the composition, chemical structure, and

Elizabeth Corinne Carr

1994-01-01

96

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

97

Distribution and Impact of Local Trapped Charges in Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) Memory  

NASA Astrophysics Data System (ADS)

In this paper we propose a two-transistor model with an RPT for the punch-through resistor in the silicon-oxide-nitride-oxide-silicon (SONOS) memory cell. With this model, the subthreshold leakage current induced by the local trapped charges in silicon nitride and the impact on the cell's read characteristics are studied. Some solutions to decrease this leakage current and change the distribution of the trapped charges are proposed and analyzed, including programming condition optimization, the channel initiated secondary electron (CHISEL) programming, and cell structure optimization. Moreover, using the CHISEL or channel hot electron (CHE) programming, the influences on the programming and the erase characteristics of different charge distributions are investigated.

Sun, Lei; Pan, Liyang; Zeng, Ying; Pang, Huiqing; Wang, Jimin; Zhang, Zhaojian; Li, Xiyou; Zhu, Jun

2005-04-01

98

Temperature dependence of metal-nitride-oxide-silicon currents at constant oxide fields  

Microsoft Academic Search

The steady-state current through the double dielectric of metal-nitride-oxide-silicon capacitors on p-silicon substrate was measured as a function of temperature for several fixed fields in the silicon oxide of a polarity-promoting hole flow from the silicon. It is shown that the availability of empty recipient trap states for holes tunneling from the silicon into the nitride controls the current. The

A. Fedotowsky; K. Lehovec; Y. K. Park

1980-01-01

99

Sputtered iron oxide/silicon heterostructures  

NASA Astrophysics Data System (ADS)

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

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

1981-03-01

100

The Active Oxidation of Silicon Carbide  

NASA Technical Reports Server (NTRS)

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

Jacobson, Nathan S.; Myers, Dwight L.

2009-01-01

101

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

102

Hydrothermal deposition and characterization of silicon oxide nanospheres  

SciTech Connect

Silicon oxide nanospheres with the average diameter of about 100 nm have been synthesized by hydrothermal deposition process using silicon and silica as the starting materials. The silicon oxide nanospheres were characterized by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) spectrum, respectively. The results show that large scale silicon oxide nanospheres with the uniform size are composed of Si and O showing the amorphous structure. Strong PL peak at 435 nm is observed demonstrating the good blue light emission property.

Pei, L.Z. [School of Materials Science and Engineering, Key Lab of Materials Science and Processing of Anhui Province, Anhui University of Technology, Maanshan 243002 (China)], E-mail: lzpei1977@163.com

2008-05-15

103

Study of thermophysical properties of crystalline silicon and silicon-rich silicon oxide layers  

NASA Astrophysics Data System (ADS)

The interaction of laser irradiation with SiOx films and process of decomposition SiOx on SiO2 and Si nanocrystals under the action of laser irradiation are investigated. Using the Comsol Multiphysics software package, the mathematical modeling of temperature distribution in a c-Si wafer and also on it's surface are carried out. It is shown that laser pulses can efficiently warm the samples of crystalline silicon. During the laser pulse of 10 ns with intensity of 52 MW/cm2 the temperature up to 2100 K can be reached on the sample surface. The experimental investigation of IR spectra of the initial and laser annealed silicon wafer coated with SiOx film confirmed the phase transformation of silicon oxide films. The changing electrical conductivity of films after laser irradiation points at changing of electron traps as a result of the film structure transformation.

Gavrylyuk, O. O.; Semchyk, O. Yu.; Bratus, O. L.; Evtukh, A. A.; Steblova, O. V.; Fedorenko, L. L.

2014-05-01

104

Ceramic oxide coatings for the corrosion protection of silicon carbide  

Microsoft Academic Search

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

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

1993-01-01

105

Formation of bottom oxides in porous silicon films by anodic oxidation  

Microsoft Academic Search

The formation of bottom oxide by electrochemical oxidation in porous silicon layers is studied. A technique of controlling the oxide layer thickness is developed. It is shown that the design of the anodization current level and of the porous silicon texture is an effective method for oxide formation control.

C. H. Lee; C. C. Yeh; K. Y. J. Hsu

1996-01-01

106

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; Baumgärtel, Thomas; Vieluf, Maik; von Borczyskowski, Christian

2008-10-01

107

Twin-bit silicon-oxide-nitride-oxide-silicon (SONOS) memory by inverted sidewall patterning (TSM-ISP)  

Microsoft Academic Search

We have proposed a new twin-bit silicon-oxide-nitride-oxide-silicon memory (TSM)-inverted sidewall patterning (ISP) cell which has twin oxide-nitride-oxides (ONOs) physically separated by the ISP method under one control gate. This TSM-ISP can control the trapped charge distribution and make diffusion barrier of charges, so that program\\/erase (P\\/E) endurance and retention can be increased. The trapping nitride is narrow enough to reduce

Yong Kyu Lee; Tae-Hun Kim; Sang Hoon Lee; Jong Duk Lee; Byung-Gook Park

2003-01-01

108

Extraction of nitride trap density from stress induced leakage current in silicon-oxide-nitride-oxide-silicon flash memory  

Microsoft Academic Search

The authors propose a technique to extract a silicon nitride trap density from stress induced leakage current in a polycrystalline silicon-oxide-nitride-oxide-silicon flash memory cell. An analytical model based on the Frenkel-Poole emission is developed to correlate a nitride trap density with stress induced leakage current. The extracted nitride trap density is 7.0×1012 cm-2 eV-1. They find that nitride trapped charges

Shaw-Hung Gu; Tahui Wang; Wen-Pin Lu; Yen-Hui Joseph Ku; Chih-Yuan Lu

2006-01-01

109

Bismuth-tin-indium alloy  

SciTech Connect

A substantially lead free low melting point, sealing alloy of bismuth, tin and indium consists essentially of 53 to 76 weight percent bismuth, 22 to 35 weight percent tin and 2 to 12 weight percent indium, said alloy being substantially resistant to atmospheric oxidation at temperatures up to 150/sup 0/C.

Kawakita, K.; Kobatake, S.; Murabayashi, H.; Nakamura, K.

1980-07-29

110

Deposition-Temperature Effect on Nitride Trapping Layer of Silicon-Oxide-Nitride-Oxide-Silicon Memory  

NASA Astrophysics Data System (ADS)

A silicon nitride film is one of the most important factors for determining the trapping efficiency of nonvolatile silicon-oxide-nitride-oxide-silicon (SONOS) memory devices. In this work, we focus on the nitride-layer deposition at different temperatures by low-pressure chemical vapor deposition (LPCVD) and examine the trap levels through photoluminescence (PL) measurement. Moreover, using DC current-voltage (I-V) and capacitance-voltage (C-V) measurements, we investigate the electrical characteristics, breakdown characteristics, and the relationship between performance and trap-level depth. Our results show that the silicon nitride deposited by LPCVD at 830 °C has better performance and reliability. However, the charge-to-breakdown (QBD) quality of the nitride film deposited at 600 °C is better due to the suppression of the influence of the transition layer near the interface at the lower deposition temperature. In summary, this study can help researchers to understand the temperature effect on nitride-film deposition and the analysis of its electrical characteristics.

Wu, Jia-Lin; Kao, Chin-Hsing; Chien, Hua-Ching; Wu, Cheng-Yen; Wang, Je-Chuang

2007-05-01

111

Four-fold reduction in the speed of light at practical power levels using Brillouin scattering in a 2-m Bismuth-oxide fiber  

Microsoft Academic Search

A 2-m long Bismuth-oxide-based highly-nonlinear fiber is used to generate Brillouin-assisted slow-light. Time delays of 46-ns and a four-fold reduction in the speed of light are achieved for 180-ns pulses with a CW pump power of just ~400-mW.

C. Jaauregui; H. Ono; P. Petropoulos; D. J. Richardson

2006-01-01

112

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

113

High temperature oxidation of Fe 9Cr 1Mo steel in stagnant liquid lead bismuth at several temperatures and for different lead contents in the liquid alloy  

NASA Astrophysics Data System (ADS)

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 lead-bismuth 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 in a T91 (Fe-9%Cr) steel container, can induce corrosion concerns. If the oxygen content dissolved in Pb-Bi is higher than the needed content for magnetite formation, corrosion proceeds by oxidation of the steel. Previously, specific results were reported, obtained in stagnant liquid LBE at 470 °C. An analytical model taking into account the oxide layer structure has been carried out. It involves iron, oxygen and chromium bulk diffusion and diffusion via preferential paths such as liquid lead-bismuth nano-channels incorporated in the oxide layer structure and grain boundaries. In this paper, experimental results on corrosion kinetics, obtained at different temperatures with different percentages of lead in the lead-bismuth alloy, are presented. The model, adapted to the different experimental conditions, is compared to these kinetics and to experimental points coming from the literature at different temperatures in LBE, in pure lead and in pure bismuth.

Martinelli, L.; Dufrenoy, T.; Jaakou, K.; Rusanov, A.; Balbaud-Célérier, F.

2008-06-01

114

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

115

Spectroscopic and microscopic investigation of the corrosion of D-9 stainless steel by lead–bismuth eutectic (LBE) at elevated temperatures. Initiation of thick oxide formation  

Microsoft Academic Search

Corrosion of 316\\/316L stainless steel by lead–bismuth eutectic (LBE) at elevated temperature was investigated by examination of samples after 1000, 2000, and 3000h of exposure at 550°C, using SEM, XPS with sputter depth profiling, and TEM. The process by which localized oxide failure becomes extensive thick oxide formation was investigated. Under our experimental conditions, iron was observed to migrate outward

Allen L. Johnson; Dan Koury; Jenny Welch; Thao Ho; Stacy Sidle; Chris Harland; Brian Hosterman; Umar Younas; Longzhou Ma; John W. Farley

2008-01-01

116

Silicon Oxide Thin Films Prepared by Vacuum Evaporation and Sputtering Using Silicon Monoxide  

NASA Astrophysics Data System (ADS)

Dependency of structural properties of silicon oxide thin films prepared using silicon monoxide source material on preparation method has been studied. The structural properties of the silicon oxide films prepared by three methods, vacuum evaporation using e-beam, rf-sputtering, and vacuum evaporation employing resistive heating are studied by IR absorption and Raman spectra. Due to the results, it is found that the structure of the films depends significantly on preparation methods. The films prepared by e-beam evaporation exhibits similar structural properties of SiO2. The film by rf-sputtering shows Raman spectrum corresponds to significantly random amorphous silicon oxide structure. The film by evaporation employing resistive heating exhibits Raman spectrum that has been explained by silicon-oxygen ring structure.

Sasaki, M.; Ehara, T.

2013-03-01

117

Indium oxide/n-silicon heterojunction solar cells  

DOEpatents

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

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

1982-12-28

118

High Temperature Oxidation and Mechanical properties of Silicon Nitride.  

National Technical Information Service (NTIS)

A summary is presented of the progress made during the four years of an investigation into the high-temperature oxidation and mechanical properties of hot-pressed silicon nitride. Progress during the fourth year of the program is emphasized.

D. Cubicciotti K. H. Lau D. J. Rowcliffe R. H. Lamoreaux

1980-01-01

119

The interface between silicon and a high-k oxide  

Microsoft Academic Search

The ability to follow Moore's Law has been the basis of the tremendous\\u000asuccess of the semiconductor industry in the past decades. To date, the\\u000agreatest challenge for device scaling is the required replacement of silicon\\u000adioxide-based gate oxides by high-k oxides in transistors. Around 2010 high-k\\u000aoxides are required to have an atomically defined interface with silicon\\u000awithout any

Clemens J. Först; Christopher R. Ashman; Karlheinz Schwarz; Peter E. Blöchl

2004-01-01

120

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

121

Oxygen depletion of bismuth molybdates  

Microsoft Academic Search

Pure ..cap alpha..-phase bismuth molybdate (BiâMoâOââ), which is known to be weakly active for selective oxidation, and pure ..gamma..-phase bismuth molybdate (BiâMoOâ), which has good activity, were subjected to oxidation-reduction cycles with known amounts of hydrogen and oxygen, at 300°⁻⁵⁷°sup 0\\/C and with evacuation steps between treatments. The volume of oxygen consumed during reoxidation was equal to half the hydrogen

L. K. Yong; R. F. Howe; G. W. Keulks; W. K. Hall

1978-01-01

122

Temperature dependence of metal-nitride-oxide-silicon currents at constant oxide fields  

NASA Astrophysics Data System (ADS)

The steady-state current through the double dielectric of metal-nitride-oxide-silicon capacitors on p-silicon substrate was measured as a function of temperature for several fixed fields in the silicon oxide of a polarity-promoting hole flow from the silicon. It is shown that the availability of empty recipient trap states for holes tunneling from the silicon into the nitride controls the current. The occupancy of these trap states is governed by Frenkel-Poole detrapping at elevated temperatures and by Fowler-Nordheim tunnel emission from the traps at low temperature. Transient charging measurements support this interpretation.

Fedotowsky, A.; Lehovec, K.; Park, Y. K.

1980-11-01

123

Analytical solutions to the one-dimensional oxide-silicon-oxide system  

Microsoft Academic Search

Analytical solutions to the one-dimensional (1-D) double-side gated oxide-silicon-oxide (OSO) system are derived. The solution space, parameterized by the gate bias conditions, is divided into two separate regions, admitting either a \\

Xuejie Shi; Man Wong

2003-01-01

124

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

125

Single-layer graphene oxide films on a silicon surface  

NASA Astrophysics Data System (ADS)

A method is proposed to produce large-area single-layer graphene oxide films on the surface of semiconductor silicon wafers by precipitation from aqueous suspensions. Graphene oxide is synthesized from natural crystalline graphite during chemical oxidation and represents a wide-gap insulator. Single-layer graphene with a homogeneous-fragment size up to 50 ?m can be formed by the reduction of graphene oxide films, and this size is significantly larger than those achieved to date.

Aleksenskii, A. E.; Brunkov, P. N.; Dideikin, A. T.; Kirilenko, D. A.; Kudashova, Yu. V.; Sakseev, D. A.; Sevryuk, V. A.; Shestakov, M. S.

2013-11-01

126

The role of strontium in oxide epitaxy on silicon (001).  

NASA Astrophysics Data System (ADS)

The integration of crystalline oxides and semiconductors has been made possible by the development of techniques that allow crystalline SrTiO3 to be grown on the silicon (001) surface. The most successful approach to realizing these epitaxial oxide-silicon (001) heterostructures requires manipulating substrate temperature and oxygen pressure on a layer-by-layer basis during the deposition of the metal oxide layers. The transition layer between the semiconductor and crystalline oxide is an alkaline earth metal, most often strontium, that is deposited on the silicon surface at around 650 C. Motivated by the desire to develop a fundamental understanding of this important transition layer, we have studied the surface structures formed by strontium on miscut silicon wafers, which, unlike regular silicon wafers, have a unique surface termination. At high temperatures, this reaction rearranges the top layer of silicon to replace the original top layer with strontium. At low temperatures, this reaction is suppressed, leading to a different, but symmetry related, ordered surface structure. We find that complex oxides can be grown on either surface with comparable crystallinity.

Reiner, James; Garrity, Kevin; Walker, Fred; Ismail-Beigi, Sohraib; Ahn, Charles

2009-03-01

127

Extraction of nitride trap density from stress induced leakage current in silicon-oxide-nitride-oxide-silicon flash memory  

NASA Astrophysics Data System (ADS)

The authors propose a technique to extract a silicon nitride trap density from stress induced leakage current in a polycrystalline silicon-oxide-nitride-oxide-silicon flash memory cell. An analytical model based on the Frenkel-Poole emission is developed to correlate a nitride trap density with stress induced leakage current. The extracted nitride trap density is 7.0×1012 cm-2 eV-1. They find that nitride trapped charges have a rather uniform distribution in an energy range of measurement (~0.2 eV).

Gu, Shaw-Hung; Wang, Tahui; Lu, Wen-Pin; Ku, Yen-Hui Joseph; Lu, Chih-Yuan

2006-10-01

128

The induction of heme oxygenase-1 modulates bismuth oxide-induced cytotoxicity in human dental pulp cells.  

PubMed

The aim of this study was to investigate the cytotoxic and nitric oxide (NO)-inducing effects of bismuth oxide (Bi(2)O(3))-containing Portland cement (BPC) on human dental pulp cells. We also assessed whether heme oxygenase-1 (HO-1) is involved in BPC-induced cytotoxicity in dental pulp cells. Cytotoxicity and NO production induced by BPC were higher than those induced by Portland cement at 12 and 24 hours, and the former gradually decreased to the level observed for PC. HO-1 and inducible nitric oxide synthase messenger RNA expressions in the BPC group showed maximal increase at 24 hours, and it gradually decreased with increasing cultivation time. Hemin treatment reversed the BPC-induced cytotoxicity, whereas zinc protoporphyrin IX treatment increased the cytotoxicity. These results suggested that NO production by BPC correlates with HO-1 expression in dental pulp cells. Moreover, BPC-induced HO-1 expression in dental pulp cells plays a protective role against the cytotoxic effects of BPC. PMID:17963960

Min, Kyung-San; Chang, Hoon-Sang; Bae, Ji-Myung; Park, Sang-Hyuk; Hong, Chan-Ui; Kim, Eun-Cheol

2007-11-01

129

Synthesis and characterization of iron oxide nanoparticles dispersed in mesoporous aluminum oxide or silicon oxide  

Microsoft Academic Search

Iron oxide nanoparticles dispersed in aluminum (Al) or silicon (Si) oxides were prepared via a polymeric precursor derived\\u000a from the Pechini method. The samples were characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy,\\u000a X-ray diffraction, N2 adsorption\\/desorption isotherms (Brunauer–Emmett–Teller, BET), Mössbauer spectroscopy, and vibrating sample magnetometry\\u000a (VSM). BET analysis shows that the samples are mesoporous materials and have a high surface

Tiago Pinheiro Braga; Antônio Narcísio Pinheiro; W. T. Herrera; Y. T. Xing; E. Baggio-Saitovitch; Antoninho Valentini

2011-01-01

130

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

Microsoft Academic Search

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

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

2004-01-01

131

Amorphous phase in electrochemically oxidized porous silicon  

Microsoft Academic Search

An amorphous phase has been demonstrated in porous silicon prepared by anodization of silicon wafers. The radial distribution function has been calculated on the basis of the X-ray diffraction pattern recorded from a typical sample. There was revealed an amorphous phase of composition SiO1–6.

Mihai A. Popescu; Valentin N. Chumash; Ion Cojocaru; Vinod K. Jain; Amita Gupta

1996-01-01

132

Reactions of silicon carbide with oxidizing atmospheres  

Microsoft Academic Search

During the operation of silicon carbide materials in thermally stressed elements of electrothermal, metallurgical, and power plants (various types of lining, heat exchangers, electric heating elements, etc.) heterogeneous reactions take place between the solid silicon carbide and chemically active gaseous media (air, organic fuel combustion products, and the like). Air and combustion products consist mainly of nitrogen, oxygen, water vapor,

I. A. Yavorskii; V. I. Elchin; G. G. Gnesin

1978-01-01

133

Engineering silicon oxide surfaces using self-assembled monolayers  

Microsoft Academic Search

Although a molecular monolayer is only a few nanometers thick it can completely change the properties of a surface. Molecular monolayers can be readily prepared using the Langmuir-Blodgett methodology or by chemisorption on metal and oxide surfaces. This Review focuses on the use of chemisorbed self-assembled monolayers (SAMs) as a platform for the functionalization of silicon oxide surfaces. The controlled

Steffen Onclin; Bart Jan Ravoo; David N. Reinhoudt

2005-01-01

134

An atomistic insight into the corrosion of the oxide film in liquid lead-bismuth eutectic.  

PubMed

When used as a protective scale, the Fe3O4 layer covering the stainless steel surface in accelerator driven subcritical systems (ADS) is corroded by liquid lead-bismuth eutectics (LBE). By performing theoretical calculations, we reveal that both Pb and Bi at the interface between the LBE and the Fe3O4 scale, favorably adsorb onto the Fe3O4 surfaces, weakening the strength of Fe-O bonds nearby significantly. This facilitates the movement of iron atoms toward the deposited Pb(Bi) and away from the Fe3O4 surface, thus causing corrosion. Such corrosion behavior becomes severe if oxygen vacancies exist in the surface region. PMID:24626636

Li, Dongdong; Song, Chi; He, H Y; Liu, C S; Pan, B C

2014-04-28

135

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

136

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

137

Zinc oxide varistors and/or resistors  

SciTech Connect

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

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

1993-07-27

138

Novel lead-free piezoelectric ceramics in the solid solution (1-x) bismuth iron oxide-barium titanate  

NASA Astrophysics Data System (ADS)

Piezoelectric materials are widely used in many areas of science and technology due to their electromechanical properties. The transformation of mechanical energy into electrical signals and vice versa based on the piezoelectric effect has led to the development of sensor devices and piezoelectric actuators used in accelerometers, pressure and vibration meters, micropositioning devices, ultrasound generators, motors etc. The most technologically important piezoelectric material is lead zirconate titanate PbZrO3-PbTiO3 (PZT), however, the commercial manufacture and application of PZT as a lead-based material represent serious health hazards. The need to reduce environmental contamination by lead-based substances has created the current drive to develop alternative lead-free piezoelectric materials. The present work describes a detailed investigation of the novel multifunctional ceramic material in a solid solution of bismuth iron oxide and barium titanate (1-x)BiFeO 3-xBaTiO3 (BFBT) with an emphasis on the room temperature piezoelectric properties and structural study. BFBT ceramics were prepared via the metal oxide solid-state preparation route. Addition of manganese oxide MnO2 increased the DC resistance by one to five orders of magnitude allowing high-field poling and piezoelectric strain measurements in Mn-modified BFBT ceramics. Piezoelectric d33 coefficients of 116 pC/N (low-field, Berlincourt) and 326 pC/N (effective, high-field) are reported for the compositions with x=0.25 and 0.33 respectively. Piezoelectric measurements using the Rayleigh law under applied large DC electric field indicated an increased low-field piezoelectric d33 coefficient to 150 pC/N (x=0.33). The DC bias is believed to stabilize the ferroclectric domain structure leading to stronger intrinsic and extrinsic contributions to the piezoelectric response in BFBT. Bright field TEM imaging confirmed formation of macroscopic domains following high field poling from initially frustrated domain state indicating the ability to induce long-range polarization order in BFBT ceramics. It is believed that the results of this work will contribute to the development of a family of lead-free piezoelectric materials based on BiFeO3-BaTiO3 system. KEYWORDS: Bismuth ferrite, Barium titanate, Lead-free, Piezoelectric ceramics, Crystal Structure

Leontsev, Serhiy

139

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

2013-09-25

140

Bipolar stressing, breakdown, and trap generation in thin silicon oxides  

Microsoft Academic Search

Thin silicon oxide films were stressed with bipolar pulses in which the magnitudes of both the positive and negative pulses were independently varied, The time-to-breakdown, the charge-to-breakdown, and the number of traps generated inside of the oxides during the stresses were measured and compared with oxides that had been stressed with unipolar pulses or stressed with constant dc voltages. For

D. J. Dumin; S. Vanchinathan

1994-01-01

141

Oxidation of mullite-zirconia-alumina-silicon carbide composites  

SciTech Connect

This paper reports the isothermal oxidation of mullite-alumina-zirconia-silicon carbide composites obtained by reaction sintering studied in the temperature interval 800{degrees} to 1400{degrees}C. The kinetics of the oxidation process was related to the viscosity of the surface glassy layer as well as to the crystallization of the surface film. The oxidation kinetics was halted to T {le} 1300{degrees}C, presumably because of crystallization.

Baudin, C.; Moya, J.S. (Instituto de Ceramica y Vidrio, Consejo Superior de Investigaciones Cientificas, 28500 Arganda del Rey, Madrid (ES))

1990-05-01

142

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

143

HUMIDITY DEGRADATION OF OXIDE-PASSIVATED DIFFUSED SILICON  

Microsoft Academic Search

The effect of humidity on diffused oxide-passivated silicon was investigated. High resistivity p-type silicon wafers were diffused with either phosphorus or boron and then passivated with 1000 Å of SiO2 before being submitted to 85% relative humidity at 85 ºC. The emitter saturation current density J0E of the samples was measured as a function of humidity exposure time and surface

Joan Cabanas Bellet; Keith R. McIntosh

144

Reduction of Silicon Vidicon Dark Current by HCl Oxidation  

Microsoft Academic Search

The silicon vidicon dark current was markedly reduced by forming the target oxide layer in a mixture of dry O2 and a small amount of HCl. Dark current of less than 0.6 nA, which is about ten times smaller than has ever been reported, was realized in a standard 1'' silicon vidicon. It was found that this dark current reduction

Hiromitsu Shiraki

1975-01-01

145

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

146

Demonstration of slot-waveguide structures on silicon nitride \\/ silicon oxide platform  

Microsoft Academic Search

We report on the first demonstration of guiding light in vertical slot-waveguides on silicon nitride\\/silicon oxide material system. Integrated ring resonators and Fabry-Perot cavities have been fabricated and characterized in order to determine optical features of the slot-waveguides. Group index behavior evidences guiding and confinement in the low-index slot region at O-band (1260-1370nm) telecommunication wavelengths. Propagation losses of <20 dB\\/cm

C. A. Barrios; B. Sánchez; K. B. Gylfason; A. Griol; H. Sohlström; M. Holgado; R. Casquel

2007-01-01

147

Oxidation kinetics of CVD silicon carbide and silicon nitride  

NASA Technical Reports Server (NTRS)

The long-term oxidation behavior of pure, monolithic CVD SiC and Si3N4 is studied, and the isothermal oxidation kinetics of these two materials are obtained for the case of 100 hrs at 1200-1500 C in flowing oxygen. Estimates are made of lifetimes at the various temperatures investigated. Parabolic rate constants for SiC are within an order of magnitude of shorter exposure time values reported in the literature. The resulting silica scales are in the form of cristobalite, with cracks visible after exposure. The oxidation protection afforded by silica for these materials is adequate for long service times under isothermal conditions in 1-atm dry oxygen.

Fox, Dennis S.

1992-01-01

148

Catalytic synthesis and photoluminescence of silicon oxide nanowires and nanotubes  

NASA Astrophysics Data System (ADS)

A large quantity of nanowires and nanotubes of silicon oxide are produced by using Fe Co Ni alloy nanoparticles as catalyst. The products have a uniform diameter of around 100 nm. The nanowires have a smooth surface and the lengths are up to 100 ?m or more. A new morphology called a serrated joint nanotube was found. The alloy catalyst plays a key role in the synthesis process. Room-temperature photoluminescence measurement under excitation at 360 nm showed that the silicon oxide had a strong blue-green emission at 525 nm (about 2.36 eV), which may be related to oxygen defects.

Jiang, Z.; Xie, T.; Yuan, X. Y.; Geng, B. Y.; Wu, G. S.; Wang, G. Z.; Meng, G. W.; Zhang, L. D.

2005-08-01

149

Ion implantation reduces radiation sensitivity of metal oxide silicon /MOS/ devices  

NASA Technical Reports Server (NTRS)

Implanting nitrogen ions improves hardening of silicon oxides 30 percent to 60 percent against ionizing radiation effects. Process reduces sensitivity, but retains stability normally shown by interfaces between silicon and thermally grown oxides.

1971-01-01

150

Spectroscopic and microscopic investigation of the corrosion of D-9 stainless steel by lead bismuth eutectic (LBE) at elevated temperatures. Initiation of thick oxide formation  

NASA Astrophysics Data System (ADS)

Corrosion of 316/316L stainless steel by lead-bismuth eutectic (LBE) at elevated temperature was investigated by examination of samples after 1000, 2000, and 3000 h of exposure at 550 °C, using SEM, XPS with sputter depth profiling, and TEM. The process by which localized oxide failure becomes extensive thick oxide formation was investigated. Under our experimental conditions, iron was observed to migrate outward while chromium did not migrate above the original metal surface. The thin oxide layer on the D-9 sample resembled 316L cold-rolled samples, while the thick oxide on D-9 resembled annealed 316L oxide. With continued exposure, thick oxide grew to cover the entire surface.

Johnson, Allen L.; Koury, Dan; Welch, Jenny; Ho, Thao; Sidle, Stacy; Harland, Chris; Hosterman, Brian; Younas, Umar; Ma, Longzhou; Farley, John W.

2008-06-01

151

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

152

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

153

The Oxidation of CVD Silicon Carbide in Carbon Dioxide  

NASA Technical Reports Server (NTRS)

Chemically-vapor-deposited silicon carbide (CVD SiC) was oxidized in carbon dioxide (CO2) at temperatures of 1200-1400 C for times between 100 and 500 hours at several gas flow rates. Oxidation weight gains were monitored by thermogravimetric analysis (TGA) and were found to be very small and independent of temperature. Possible rate limiting kinetic laws are discussed. Oxidation of SiC by CO2 is negligible compared to the rates measured for other oxidants typically found in combustion environments: oxygen and water vapor.

Opila, Elizabeth J.; Nguyen, QuynchGiao N.

1997-01-01

154

Dopant segregation at silicon-oxide interfaces  

Microsoft Academic Search

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

Lirong Pei

2006-01-01

155

Crystallographic Symmetry of Surface State Density in Thermally Oxidized Silicon  

Microsoft Academic Search

The detailed dependence of surface state density on crystallographic orientation was determined by measuring the ac metal-oxide-semiconductor conductance on the surface of a thermally oxidized single-crystal silicon hemisphere. It was found that the ?111? poles are located at maxima, the ?100? poles at minima, and the ?110? poles at saddle points in the surface state density distribution. The symmetry of

Emil Arnold; Joshua Ladell; Gerald Abowitz

1968-01-01

156

Non uniformities of silicon oxide films grown in peroxide mixtures  

Microsoft Academic Search

The growth kinetics of silicon chemical oxides in H2O2-containing solutions at various pH values and temperatures was studied by electrochemical impedance spectroscopy (EIS), ellipsometry and X-ray photoelectron spectroscopy (XPS). Infrared (IR) spectroscopy was also used to investigate the evolution of the surface chemistry from the initial Si–H hydrogen coverage to the subsequent oxidation states by analysing the Si–O–Si stretching vibration

V. Bertagna; S. Petitdidier; N. Rochat; D. Rouchon; P. Besson; R. Erre; M. Chemla

2005-01-01

157

Polymeric waveguides using oxidized porous silicon cladding for optical amplification  

NASA Astrophysics Data System (ADS)

We report on a new hybrid approach to realize optical slab waveguides for optical amplification purposes. The structure consists of a dye-doped polymer core (PMMA) deposited over an oxidized porous silicon (PS) cladding layer formed on a silicon wafer. The very low refractive index ( n = 1.16) achievable in the cladding allows obtaining monomodal behavior with high confinement factors ( ?TE = 96%) even for very thin cores (400 nm). Optically excited guided luminescence shows stimulated emission, strong line narrowing and a clear threshold and superlinear behavior with pump energy. By means of the variable stripe length (VSL) technique, values of net optical gain up to 113 dB/cm (constant over 3 mm) and absolute amplification values up to 34 dB have been measured at 694 nm when pumping with 80 mJ/cm 2 energy pulses. These results validate the use of oxidized PS as a cladding layer in silicon photonics.

Navarro-Urrios, D.; Ghulinyan, M.; Bettotti, P.; Rigo, E.; Oton, C. J.; Capuj, N. E.; Lahoz, F.; Martín, I. R.; Pavesi, L.

2009-08-01

158

Characterization of porous silicon-on-insulator films prepared by anodic oxidation  

Microsoft Academic Search

In this paper, techniques for controlling the growth of the bottom oxide formed by simple electrochemical oxidation of porous Si films were explored and the resulting porous silicon-on-oxide structures were characterized. The thickness, uniformity, and density of the bottom oxide layer can be adjusted by selecting the porous silicon morphology and controlling the conditions of oxide formation. In particular, very

C. H Lee; C. C Yeh; H. L Hwang; Klaus Y. J Hsu

1996-01-01

159

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

SciTech Connect

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

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

1988-06-06

160

Redistribution of Diffused Boron in Silicon by Thermal Oxidation  

Microsoft Academic Search

Redistribution phenomena of diffused boron due thermal oxidation of silicon have been studied. Mathematical formulation of the redistribution phenomena is proposed and analytical solution of the problem is given approximately by the method of Green's function. Numerical calculations are carried out for several combinations of physical constants and compared with experiment. The redistribution phenomena are well described by the model

Taketoshi Kato; Yoshio Nishi

1964-01-01

161

Visible light emission from electro-oxidized porous silicon  

Microsoft Academic Search

The luminescent properties of porous silicon films are reviewed and discussed in relation with the mechanisms proposed for light emission. It is shown that a good control of the light emission is obtained by the use of electrochemically oxidized porous layers. The transient behavior of the photoluminescence is characterized, leading to propose a model for the recombination mechanisms involved in

R. Herino; S. Billat; A. Bsiesy; F. Gaspard; M. Ligeon; I. Mihalcescu; F. Muller; R. Romestain; J. C. Vial

1992-01-01

162

Effect of reaction mechanism on precursor exposure time in atomic layer deposition of silicon oxide and silicon nitride.  

PubMed

Atomic layer deposition (ALD) of highly conformal, silicon-based dielectric thin films has become necessary because of the continuing decrease in feature size in microelectronic devices. The ALD of oxides and nitrides is usually thought to be mechanistically similar, but plasma-enhanced ALD of silicon nitride is found to be problematic, while that of silicon oxide is straightforward. To find why, the ALD of silicon nitride and silicon oxide dielectric films was studied by applying ab initio methods to theoretical models for proposed surface reaction mechanisms. The thermodynamic energies for the elimination of functional groups from different silicon precursors reacting with simple model molecules were calculated using density functional theory (DFT), explaining the lower reactivity of precursors toward the deposition of silicon nitride relative to silicon oxide seen in experiments, but not explaining the trends between precursors. Using more realistic cluster models of amine and hydroxyl covered surfaces, the structures and energies were calculated of reaction pathways for chemisorption of different silicon precursors via functional group elimination, with more success. DFT calculations identified the initial physisorption step as crucial toward deposition and this step was thus used to predict the ALD reactivity of a range of amino-silane precursors, yielding good agreement with experiment. The retention of hydrogen within silicon nitride films but not in silicon oxide observed in FTIR spectra was accounted for by the theoretical calculations and helped verify the application of the model. PMID:24915469

Murray, Ciaran A; Elliott, Simon D; Hausmann, Dennis; Henri, Jon; LaVoie, Adrien

2014-07-01

163

Sub-50 nm 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 40 nm to several microns in length. We demonstrate that an ionic tetrathiafulvalene (TTF) semiconductor can be directed from a macroscopic liquid solution (1 µM) and selectively deposited onto predefined nanoscale regions of a 1 cm(2) silicon chip with an accuracy of 40 nm. PMID:21832773

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

2008-11-12

164

BISMUTH BINDS…  

Microsoft Academic Search

ABSTRACTMicroscopic colitis (MC), is a chronic diarrheal syndrome with mild mucosal inflammation detected only by mucosal biopsy. In this study, they combine “lymphocytic” colitis and collagenous colitis (see below). The etiology and pathogenesis are unknown. The diarrhea can be debilitating and there is no uniformly effective therapy. This open trial of 13 patients with MC tested chewable bismuth subsalicylate tablets

Christina Surawicz

1999-01-01

165

Optimization of amorphous silicon double junction solar cells for an efficient photoelectrochemical water splitting device based on a bismuth vanadate photoanode.  

PubMed

A photoelectrochemical water splitting device (PEC-WSD) was designed and fabricated based on cobalt-phosphate-catalysed and tungsten-gradient-doped bismuth vanadate (W:BiVO4) as the photoanode. A simple and cheap hydrogenated amorphous silicon (a-Si:H) double junction solar cell has been used to provide additional bias. The advantage of using thin film silicon (TF-Si) based solar cells is that this photovoltaic (PV) technology meets the crucial requirements for the PV component in PEC-WSDs based on W:BiVO4 photoanodes. TF-Si PV devices are stable in aqueous solutions, are manufactured by simple and cheap fabrication processes and their spectral response, voltage and current density show an excellent match with the photoanode. This paper is mainly focused on the optimization of the TF-Si solar cell with respect to the remaining solar spectrum transmitted through the W:BiVO4 photoanode. The current matching between the top and bottom cells is studied and optimized by varying the thickness of the a-Si:H top cell. We support the experimental optimization of the current balance between the two sub-cells with simulations of the PV devices. In addition, the impact of the light induced degradation of the a-Si:H double junction, the so-called Staebler-Wronski Effect (SWE), on the performance of the PEC-WSD has been studied. The light soaking experiments on the a-Si:H/a-Si:H double junctions over 1000 hours show that the efficiency of a stand-alone a-Si:H/a-Si:H double junction cell is significantly reduced due to the SWE. Nevertheless, the SWE has a significantly smaller effect on the performance of the PEC-WSD. PMID:24452785

Han, Lihao; Abdi, Fatwa F; Perez Rodriguez, Paula; Dam, Bernard; van de Krol, Roel; Zeman, Miro; Smets, Arno H M

2014-03-01

166

Density difference related to humidity during dry oxidation for ultrathin silicon oxide films  

Microsoft Academic Search

The densities of 3.5-6.5-nm-thick silicon oxide films grown on p-type Si(100) at humidities during dry oxidation of 0.5-1.0, 10-100 ppb and 200-500 ppm were determined by charged-particle activation analysis. It was confirmed that the density increases with decreasing humidity and its level is separated into two groups: an ultradry oxidation group that includes the films oxidized at a humidity of

Hiroshi Yamada

1999-01-01

167

Coverage of palladium by silicon oxide during reduction in H 2 and complete oxidation of methane  

Microsoft Academic Search

The interaction between silica and palladium following complete oxidation of methane or following reduction in H2 was investigated on a polycrystalline palladium foil and on supported Pd\\/SiO2 catalysts. During methane oxidation, oxidized silicon covered the palladium oxide surface as observed by TEM on Pd\\/SiO2 catalysts and by XPS on palladium foil. On the Pd foil, the source of silica was

Guanghui Zhu; Ken-ichiro Fujimoto; Dmitri Yu. Zemlyanov; Abhaya K. Datye; Fabio H. Ribeiro

2004-01-01

168

An investigation of instability and charge motion in metal-silicon oxide-silicon structures  

Microsoft Academic Search

The results of a detailed study of the charge motion and instability in thermally grown, undoped silicon dioxide films at high electric fields and elevated temperatures are presented. The transient behavior of the charge motion in the oxide is analyzed and a model proposed to explain the observations. It is shown that the instability consists of the motion of positively

S. R. Hofstein

1966-01-01

169

Photon-induced formation of silicon oxide thin films  

NASA Astrophysics Data System (ADS)

Silicon oxide thin films are widely used in numerous technologies such as microelectronics, coatings, and food packaging. The conventional techniques to deposit silicon oxide thin films have drawbacks such as high temperature, unsuitable for planarization, and unstable precursors. In this thesis, it is shown that uv photons can be used to induce conversion of spin-coated thin films of beta-chloroethyl silsesquioxane (beta-cesq) on a substrate to silicon oxide. This method not only overcomes the above mentioned drawbacks, but has the added advantage of spatially selective deposition. The photo-induced oxide is found to be superior to the thermally induced oxide regarding the impurity concentration of carbon. A variety of techniques are utilized in investigating the mechanism of the photochemical conversion of beta-cesq to silicon oxide: Infra-red, UV absorption spectroscopy, Ellipsometry, Rutherford backscattering spectrometry, Atomic force microscopy, Mass spectrometry, and Time-of-flight mass spectrometry. The photo-induced conversion is initiated by the direct excitation of the RSiO chromophore of the beta-cesq molecules, resulting in the breaking of the Si-C bond. The primary photo-fragment was found to be ethyl chloride radical, while ethylene and vinyl chloride were determined to be secondary photo-fragments. The majority of the secondary photo-fragments are formed deep inside the thin film, due to further reactions of primary photo-fragments as they diffuse out of the film. A diffusion-reaction model was proposed to explain the observations of: one reaction rate for thin film (400 A) while two for thick films (2000 A) in the thickness measurements versus integrated fluence; different time behavior of different photofragments as a function of integrated fluence; and the difference in the time-of-flight signal (arrival time and decay constant) for various masses for thin and thick films. It was also found that a source of oxygen is crucial to the photochemical and thermally-induced conversion of beta-cesq to silicon oxide. This study of a novel photochemical method for the deposition of silicon oxide thin films reveals some important aspects of solid state photo-chemistry in thin films: the importance of environment and the diffusion of small molecules and photo-fragments through the solid matrix.

Sharma, Jaya

170

Electrical and charge storage characteristics of the tantalum oxide-silicon dioxide device  

Microsoft Academic Search

The electrical characteristics of the tantalum oxide-silicon dioxide double-dielectric structure are described. The MTOS structure (metal-tantalum oxide-silicon dioxide-silicon) is similar to the MNOS double dielectric which is used as a nonvolatile memory element except tantalum oxide (Ta2O5) is used to replace the silicon nitride as the second dielectric. Capacitance voltage measurements show a negative QSSwith magnitudes smaller than those in

R. L. Angle; H. E. Talley

1978-01-01

171

Surface oxidation effects on the optical properties of silicon nanocrystals  

NASA Astrophysics Data System (ADS)

We report first-principles calculations for optical absorption spectra of hydrogenated silicon clusters in the presence of oxygen on the surface. Our computational technique is based on linear-response theory within the time-dependent local-density approximation (TDLDA). The calculated spectra show that oxidation substantially reduces the size of optical gaps in silicon nanocrystals. This result may explain a seeming disagreement between the measured photoluminescence and theoretical predictions based on a quantum confinement model in the limit of small clusters.

Vasiliev, Igor; Chelikowsky, James R.; Martin, Richard M.

2002-03-01

172

Synergy effects between ? and ? phases of bismuth molybdates in the selective catalytic oxidation of 1-butene  

Microsoft Academic Search

?+? mixed Bi–Mo–O phases with a large range of composition were prepared by coprecipitation for investigating the existence of synergetic effects between ? and ? phases for the oxidative dehydrogenation of 1-butene.Results from surface characterization show that the surface of the catalysts always has a composition similar to the ? phase but the ? phase grows around ? phase. Mixed

Ana Paula Vieira Soares; Lubjmir Dimitrov Dimitrov; Margarida Corte-Real André de Oliveira; Leonel Hilaire; Manuel Farinha Portela; Robert Karl Grasselli

2003-01-01

173

Coaxial nanocable: silicon carbide and silicon oxide sheathed with boron nitride and carbon  

PubMed

Multielement nanotubes comprising multiple phases, with diameters of a few tens of nanometers and lengths up to 50 micrometers, were successfully synthesized by means of reactive laser ablation. The experimentally determined structure consists of a beta-phase silicon carbide core, an amorphous silicon oxide intermediate layer, and graphitic outer shells made of boron nitride and carbon layers separated in the radial direction. The structure resembles a coaxial nanocable with a semiconductor-insulator-metal (or semiconductor-insulator-semiconductor) geometry and suggests applications in nanoscale electronic devices that take advantage of this self-organization mechanism for multielement nanotube formation. PMID:9703508

Zhang; Suenaga; Colliex; Iijima

1998-08-14

174

The surprising oxidation state of fumed silica and the nature of water binding to silicon oxides and hydroxides  

NASA Astrophysics Data System (ADS)

X-ray photoelectron spectroscopy (XPS) data demonstrate that the average formal oxidation state of silicon in fumed silica (CAB-O-SIL®) is +1 as opposed to the usual +4. Electronic structure calculations on model molecular clusters and comparison with XPS data for silicon compounds in known oxidation states suggest less hydrophilic character for CAB-O-SIL® than the oxides of silicon with Si in an average formal +3 or +4 oxidation state. Once the +3 oxidation state is formed, water on the fumed silica surface facilitates the ready conversion of the Si in an average +3 oxidation state to an average +4 oxidation state.

Wang, Tsang-Hsiu; Gole, James L.; White, Mark G.; Watkins, Clifton; Street, Shane C.; Fang, Zongtang; Dixon, David A.

2011-01-01

175

High-resolution electron microscopy and scanning tunneling microscopy of native oxides on silicon  

Microsoft Academic Search

High-resolution transmission electron microscopy and scanning tunneling microscopy have been combined to examine the structure of the thin 'native' oxide that forms on silicon surfaces at room temperature. Differences in the cleaning procedures for silicon wafers may affect the morphology of this oxide and critically influence further processing on the silicon substrates. An etch that ended with a dip in

A. H. Carim; M. M. Dovek; C. F. Quate; R. Sinclair; C. Vorst

1987-01-01

176

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

177

Silicon Surface Potential Modified by Titanium Oxide.  

National Technical Information Service (NTIS)

Chemically vapor deposited (CVD) titanium oxide offers some utility in insulated-gate devices. Films 2000A thick show breakdown voltages as large as 10 volts. The capacitance-voltage curves have very low values of off-set from zero bias because of the hig...

D. R. Harbison H. L. Taylor

1969-01-01

178

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

179

Initial oxidation of silicon (100): A unified chemical model for thin and thick oxide growth rates and interfacial structure  

Microsoft Academic Search

A model for silicon oxidation that, invokes dissociative chemisorption of molecular oxygen at the interface between silicon dioxide and silicon is described. The model accounts for a self-limiting oxide film thickness of 0.5-0.6 nm (for oxidations performed at temperatures sufficient to dissociate surface dimers and permit oxygen penetration of the substrate beyond a single monolayer of suboxide). Detailed examination of

T. K. Whidden; P. Thanikasalam; M. J. Rack

1995-01-01

180

Athermal silicon microring resonators with titanium oxide cladding.  

PubMed

We describe a novel approach for CMOS-compatible passively temperature insensitive silicon based optical devices using titanium oxide cladding which has a negative thermo-optic (TO) effect. We engineer the mode confinement in Si and TiO2 such that positive TO of Si is exactly cancelled out by negative TO of TiO2. We demonstrate robust operation of the resulting device over 35 degrees. PMID:24216877

Guha, Biswajeet; Cardenas, Jaime; Lipson, Michal

2013-11-01

181

High frequency methods for characterization of oxidized porous silicon  

Microsoft Academic Search

This paper compares insertion loss and T-resonator methods to characterize the electrical properties of oxidized porous silicon. The insertion method provided consistent dielectric and attenuation data on a range of conductive substrates, while the T-method was limited to low loss substrates. The estimated effective dielectric constant is 3.3 for a dielectric constant value of 5.6 and attenuation data at 4

R. L. Peterson; I. Itotia; R. F. Drayton

2001-01-01

182

Progress in silicon-based non-oxide structural ceramics  

Microsoft Academic Search

The progress in monolithic Si3N4 and SiC as well as in Si3N4\\/SiC-composites for structural applications is reviewed. The conventional processing including the powder synthesis, densification and microstructural design is discussed. The mechanical properties of the resulting silicon based non-oxide ceramics and their industrial applications as structural components are summarized. As an alternative route to fabricate Si3N4\\/SiC composites the hybrid processing

Wolfgang Dressler; Ralf Riedel

1997-01-01

183

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

184

The maximum dielectric strength of thin silicon oxide films  

Microsoft Academic Search

Thin film silicon oxide capacitors with nonshorting breakdowns were investigated. Breakdowns appear in three forms: single hole, self-propagating, and maximum voltage breakdowns. Single hole and self-propagating breakdowns occur at flaws, and self-propagating breakdowns develop only when the resistor to the source is relatively small, less than 10 k? in these experiments. After flaws are burned out by single hole breakdowns,

N. Klein; H. Gafni

1966-01-01

185

Thermal processing and native oxidation of silicon nanoparticles  

Microsoft Academic Search

In this study, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and electron energy\\u000a loss spectroscopy (EELS) were used to investigate in-air oxidation of silicon nanoparticles ca. 11 nm in diameter. Particle\\u000a samples were prepared first by extracting them from an RF plasma synthesis reactor, and then heating them in an inert carrier\\u000a gas stream. The resulting particles had varying

Brandon J. Winters; Jason Holm; Jeffrey T. Roberts

186

Computed light scattering cross sections of oxide particles in silicon  

Microsoft Academic Search

We have used the discrete-dipole approximation (DDA) method, implemented as a modified version of the DDSCAT program of Draine and Flatau, to calculate 3D light scattering intensity diagrams for individual oxide particles present in Czochralski silicon wafers. The particles were either octahedra or plates with normalized sizes x=0.01–5. The signals that would be measured for light scattered through 90° or

Z. Laczik; G. R. Booker

1996-01-01

187

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

188

Investigation of oxidation resistance of magnetic power coated with silicone  

NASA Astrophysics Data System (ADS)

In this work the oxidation resistance of a magnetic material of the neodymium—iron—boron (NdFeB)-type coated with silicone has been investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques. A special spin-coating technique has been used to coat the surface of the magnetic powder NdFeB. The results of TGA and DTA indicate that the oxidation resistance of the surface-treated NdFeB powder is markedly improved, while its magnetic properties do not change much compared to those of untreated material.

Zhang, Yinglan

1997-07-01

189

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

190

HAXPES study of CeOx thin film-silicon oxide interface  

NASA Astrophysics Data System (ADS)

Investigation of cerium oxide thin film deposition on silicon and silicon oxide is important due to many possible applications of cerium oxide based micro-systems in electronics and catalysis. rf-Magnetron sputtering is technologically the most suitable method of preparation of such systems. Mechanism of film growth is strongly influenced by interaction of Ce atoms with the substrate and their oxidation by oxygen containing rf plasma. We show using hard X-ray photoelectron spectroscopy with high information depth that cerium is reducing silicon oxide by forming complex silicate phase at the interface with Ce in the 3+ state. For this reason composition of very thin films of cerium oxide is strongly influenced by thin film-substrate interaction. A coating of the silicon oxide substrate by an intermediate thin carbon film provides conductive substrate for electrocatalytic applications and decreases the silicon oxide substrates-cerium oxide interaction essentially.

Vorokhta, M.; Matolínová, I.; Dubau, M.; Haviar, S.; Khalakhan, I.; Šev?íková, K.; Mori, T.; Yoshikawa, H.; Matolín, V.

2014-06-01

191

Biocompatible silicon surfaces through orthogonal click chemistries and a high affinity silicon oxide binding peptide.  

PubMed

Multifunctionality is gaining more and more importance in the field of improved biomaterials. Especially peptides feature a broad chemical variability and are versatile mediators between inorganic surfaces and living cells. Here, we synthesized a unique peptide that binds to SiO(2) with nM affinity. We equipped the peptide with the bioactive integrin binding c[RGDfK]-ligand and a fluorescent probe by stepwise Diels-Alder reaction with inverse electron demand and copper(I) catalyzed azide-alkyne cycloaddition. For the first time, we report the generation of a multifunctional peptide by combining these innovative coupling reactions. The resulting peptide displayed an outstanding binding to silicon oxide and induced a significant increase in cell spreading and cell viability of osteoblasts on the oxidized silicon surface. PMID:22989005

Hassert, Rayk; Pagel, Mareen; Ming, Zhou; Häupl, Tilmann; Abel, Bernd; Braun, Klaus; Wiessler, Manfred; Beck-Sickinger, Annette G

2012-10-17

192

Silver oxide nanostructure prepared on porous silicon for optoelectronic application  

NASA Astrophysics Data System (ADS)

The thermal evaporation system type (Edwards) has been used to evaporate high purity (99.9 %) silver on glass, n- and p-type silicon and porous silicon substrates at room temperature under low pressure (about 10-6 torr) for different thickness (50, 75, 100, 125 and 150 nm). Using a rapid thermal oxidation of Ag film at oxidation temperature 350 °C and different oxidation times, Ag2O thin film was prepared. The structural properties of Ag2O film were investigated and compared with other published results. The structural investigation showed that the films formed at thickness 100 nm showed (111) strong reflection along with weak reflections of (101) corresponding to the growth of single phase Ag2O with cubic structure. Dark and illuminated I-V of p-Ag2O/ p-Si, p-Ag2O/ n-Si, Al/ p-PSi/Al, Al/ n-PSi/Al, p-Ag2O/ p-PSi/c-Si and p-Ag2O/ n-PSi/c-Si heterojunction were investigated, discussed and prepared at optimum condition (oxidation temperature 350 °C and 90 s oxidation time with thickness 100 nm). Ohmic contacts were fabricated by evaporating 99.999 purity silver wires for back and aluminum wires for front contact, respectively.

Hassan, Marwa Abdul Muhsien; Agool, Ibrahim Ramdan; Raoof, Lamyaa Mohammed

2014-04-01

193

Electron trap density distribution of Si-rich silicon nitride extracted using the modified negative charge decay model of silicon-oxide-nitride- oxide-silicon structure at elevated temperatures  

Microsoft Academic Search

The authors modified the charge decay model of silicon-oxide-nitride-oxide-silicon-type memory at the temperatures above 150 °C. The modified model includes the effect of the internal electric field induced by the charges trapped in silicon nitride layer. The authors extracted the trap density distributions in energy level of the Si-rich silicon nitride using the model and compared them with those of

Tae Hun Kim; Jong Duk Lee; Hyung Cheol Shin; Byung-Gook Park

2006-01-01

194

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 1450°C (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

195

Oxidation of silicon surface with atomic oxygen radical anions  

NASA Astrophysics Data System (ADS)

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 (0.5 ?A/cm2) at 300°C for 1-10 hours, the Si wafer achieves an oxide layer with a thickness ranging from 8 to 32 nm. X-ray photoelectron spectroscopy (XPS) results reveal that the oxide layer is of a mixture of SiO2, Si2O3, and Si2O distributed in different oxidation depths. The features of the MOS capacitor of < Al electrode/SiOx/SI > are investigated by measuring capacitance-voltage (C — V) and current-voltage (I — V) curves. The oxide charge density is about 6.0 × 1011 cm-2 derived from the C — V curves. The leakage current density is in the order of 10-6A/cm2 below 4MV/cm, obtained from the I — V curves. The O- anions formed by present method would have potential applications to the oxidation and the surface-modification of materials together with the preparation of semiconductor devices.

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

2008-06-01

196

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

Microsoft Academic Search

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,

H. García; S. Dueñas; H. Castán; A. Gómez; L. Bailón; M. Toledano-Luque; A. Del Prado; I. Mártil; G. González-Díaz

2008-01-01

197

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

198

New Through-Wafer Via Interconnections with Thick Oxidized Porous Silicon Sidewall Via  

Microsoft Academic Search

In this paper, we present the detailed fabrication process and high-frequency characterization of a new silicon through-wafer via interconnection and a low pass filter module flip-chip bonded to these via interconnections. An oxide liner of 18 mum thick for the via was fabricated on a complementary metal-oxide-semiconductor (CMOS)-grade low-resistivity 5 Omega\\\\cdotcm silicon wafer using the oxidized porous silicon (OPS) process.

Bun-Joong Kim; Man-Lyun Ha; Young-Se Kwon

2006-01-01

199

Investigation of PEMFC operation above 100 °C employing perfluorosulfonic acid silicon oxide composite membranes  

Microsoft Academic Search

Various perfluorosulfonic acid membranes (PFSAs) were studied as pure and silicon oxide composite membranes for operation in hydrogen\\/oxygen proton-exchange membrane fuel cells (PEMFCs) from 80 to 140°C. The composite membranes were prepared either by impregnation of pre-formed PFSAs via sol–gel processing of a polymeric silicon oxide, recasting a film using solubilized PFSAs and a silicon oxide polymer\\/gel. All composite membranes

K. T Adjemian; S Srinivasan; J Benziger; A. B Bocarsly

2002-01-01

200

In situ imaging of the conducting filament in a silicon oxide resistive switch  

PubMed Central

The nature of the conducting filaments in many resistive switching systems has been elusive. Through in situ transmission electron microscopy, we image the real-time formation and evolution of the filament in a silicon oxide resistive switch. The electroforming process is revealed to involve the local enrichment of silicon from the silicon oxide matrix. Semi-metallic silicon nanocrystals with structural variations from the conventional diamond cubic form of silicon are observed, which likely accounts for the conduction in the filament. The growth and shrinkage of the silicon nanocrystals in response to different electrical stimuli show energetically viable transition processes in the silicon forms, offering evidence for the switching mechanism. The study here also provides insights into the electrical breakdown process in silicon oxide layers, which are ubiquitous in a host of electronic devices.

Yao, Jun; Zhong, Lin; Natelson, Douglas; Tour, James M.

2012-01-01

201

Transparent conducting oxides (TCO's) for amorphous silicon solar cells  

NASA Astrophysics Data System (ADS)

The stability of various textured tin oxide and zinc oxide transparent conductors was evaluated against annealing in air, in vacuum or exposed to hydrogen plasma. Only fluorine-doped zinc oxide deposited by atmospheric pressure chemical vapor deposition (APCVD) had stable electrical and optical properties under all conditions. Thin layers of ZnO or TiO2 greatly improved the plasma resistance of SnO2. A new TCO material, niobium-doped titanium dioxide (TiO2:Nb) was able to withstand hydrogen plasmas with only slight increases in its optical absorption and conductivity. Composite TCO's consisting of glass/SnO2:F/TiO2:Nb were shown to provide good electrical contact to amorphous silicon solar cells.

Hegedus, Steven; Liang, Haifan; Gordon, Roy G.

1996-01-01

202

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

2013-11-01

203

Boron diffusion through pure silicon oxide and oxynitride used for metal-oxide-semiconductor devices  

Microsoft Academic Search

We studied boron diffusion in thin silicon oxides including pure SiO2 and oxynitride that are used for metal-oxide semiconductor transistors. We measured the boron penetration using secondary ion mass spectroscopy. By comparing simulated and experimental results, we found that the boron diffusivity in pure SiO2, D(sub PO), is 3.96 x 10(exp -2)exp (-3.65 eV\\/kT) cm(exp 2)\\/s, and that in oxynitride

Takayuki Aoyama; Kunihiro Suzuki; Hiroko Tashiro; Yaka Tada; Tatsuya Yamazaki; Yoshihiro Armoto; Takashi Ito

1993-01-01

204

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

Microsoft Academic Search

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

Ming-Tsung Ho

2008-01-01

205

Mobile-Ion-Induced Charge Loss Failure in Silicon-Oxide-Nitride-Oxide-Silicon Two-Bit Storage Flash Memory  

NASA Astrophysics Data System (ADS)

In silicon-oxide-nitride-oxide-silicon (SONOS) 2-bit storage flash memory, we discovered deterioration of data retention (DR) in the form of charge loss, which is dependent on the distance between contact windows and word lines (WLs) and also on the thermal treatment performed after the formation of contact windows. We hypothesized that the unique structure of the SONOS flash memory leads to susceptibility to mobile ion contamination. We concluded that Na mobile ion contamination originates in the tungsten chemical-mechanical polishing (W-CMP) process, and that the ions diffuse through the boundaries of the boron phosphosilicate glass (BPSG) and stacked oxide-nitride-oxide (ONO) films into the cell area. We successfully reduced the charge loss by cleaning of the contamination source and by the stable control of phosphorus concentration at the bottom of the BPSG. As a permanent countermeasure, we proposed the complete isolation of contact windows from the adjacent ONO layer, and we were able to demonstrate the effectiveness of this proposal.

Imaoka, Kazunori; Higashi, Masahiko; Shiraiwa, Hidehiko; Inoue, Fumihiko; Kajita, Tatsuya; Sugawa, Shigetoshi

2009-06-01

206

Fast Shrinkage of Oxidation Stacking Faults during O2/NF3 Oxidation of Silicon. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

The behavior of oxidation-induced stacking faults (OSF's) during the O2/NF3 oxidation of silicon has been investigated in the temperature range of 850-1100 C. A very fast shrinkage rate of pregrown OSF in silicon and a nonlinear shrinkage rate with time h...

U.S. Kim R. J. Jaccodine

1986-01-01

207

Anodic oxidation during MEMS processing of silicon and polysilicon: native oxides can be thicker than you think  

Microsoft Academic Search

The thickness and surface roughness of the native oxide on undoped and P-doped single crystal silicon and polycrystalline silicon (polysilicon) were measured after exposure to aqueous hydrofluoric acid (HF) in the presence of localized metallization of sputtered Au or Pd. Both P-doping and the presence of metallization led to an increase in the thickness of the native surface oxide and

Harold Kahn; Chris Deeb; Ioannis Chasiotis; Arthur H. Heuer

2005-01-01

208

Cost efficient synthesis of bismuth aminoalkoxides from bismuth oxide: Molecular structure of [Bi 2(mdea) 2(mdeaH) 2](mdeaH 2) 2  

Microsoft Academic Search

Functional Bi alkoxides were prepared by reaction between the oxide and diols such as N-methyldiethanolamine (mdeaH2), diethanolamine (deaH2) and triethanolamine (teaH3) in refluxing toluene in high yields. Similar reactions with polyols without N-donor site lead to oxo species. The derivative obtained with N-methyldiethanolamine was characterised by X-ray diffraction as a dimer [Bi2(mdea)2(mdeaH)2] associated as chains through H-bonding with neutral diol

Jérome Le Bris; Liliane G. Hubert-Pfalzgraf; Stéphane Daniele; Jacqueline Vaissermann

2007-01-01

209

Origin of complex impact craters on native oxide coated silicon surfaces  

SciTech Connect

Crater structures induced by impact of keV-energy Ar{sub n}{sup +} 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 5 keV/atom Ar{sub 12} cluster impacts, transient displacements of the amorphous silicon or silicon oxide substrate surfaces are induced in an approximately 50 nm 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. [Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Espoo (Finland); Department of Physics, Gothenburg University, 41296 Gothenburg (Sweden); Department of Physics, Gothenburg University, 41296 Gothenburg, Sweden and School of Chemistry, Edinburgh University, West Mains Road, Edinburgh EH9 3JJ, Scotland (United Kingdom)

2008-02-15

210

Observation of natural oxide growth on silicon facets using an atomic force microscope with current measurement  

Microsoft Academic Search

Natural oxide growth on silicon facets is observed through an atomic force microscope (AFM) with current measurement. The sample is prepared by means of cleaning and heating a silicon (111) surface with direct electric heating in an ultrahigh vacuum, which creates various facets formed by step bunching. The silicon facets and steps can be observed with the AFM in air.

Sumio Hosaka; Hajime Koyanagi; Tsuyoshi Hasegawa; Shigeyuki Hosoki; Atsushi Hiraiwa

1992-01-01

211

Oxidation of silicon and germanium by atomic and molecular oxygen  

NASA Astrophysics Data System (ADS)

Space vehicles residing in the low Earth orbit (LEO) are exposed to a harsh environment that rapidly degrades their materials. The LEO ranges from 200-700km in altitude from the Earth's surface, and the temperature varies between 200 and 400K. The most hazardous species in LEO is atomic oxygen (AO) containing 5eV kinetic energy due to the high velocity of the spacecrafts (8km/s). The goal of this research is the elucidation of the fundamental mechanisms of semiconductor degradation and passivation in LEO conditions by comparing the structural differences in the oxide films created by exposure to AO and molecular oxygen (MO). Silicon is the base material for solar cells used in LEO whereas Ge and SiOx films are common coatings to protect polymer materials that are used as structural materials in spacecrafts. Hyperthermal AO was created by the laser detonation of MO within a high vacuum (HV) chamber, that produces a high flux of AO. A variety of nano-characterization techniques, including high resolution transmission electron microscopy (HREM), and electron energy loss spectroscopy (EELS) were used to determine the microstructure and local chemistry of the oxide and the oxide/semiconductor interface. For Si, the amorphous silica formed by AO was nearly twice as thick, more ordered, and more homogeneous in composition, than the oxide formed by MO. The Si/SiOx interface formed by AO was atomically abrupt, with no suboxides detected near the interface or throughout the oxide. The oxide scale formed by MO on Si(100) consisted of transitional oxidation states. The oxide film formed on Ge(100) due to exposure to 5eV AO, is 2-3 times thicker and similarly to the Si/SiOx interfaces, the Ge/GeOx interface was found to be atomically abrupt. The oxidation kinetics of Si and Ge were monitored in situ using a research quartz crystal microbalance (RQCM) that was incorporated into the AO source. The oxidation kinetics in hyperthermal AO did not follow the standard linear to parabolic Deal-Grove kinetics. A novel oxidation model, based on the oxide structure continually changing during AO exposure, is proposed to explain the unusual power law oxidation kinetics.

Kisa, Maja

212

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

213

Fluorine-Enhanced Oxidation of Silicon. Effects of Fluorine on Oxide Stress and Growth Kinetics. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

The influence of fluorine on film stress as well as on oxide growth kinetics for oxide films grown by fluorine-enhanced thermal oxidation of silicon using NF3 as fluorine source is reported. The effect of NF3 concentration and oxidation temperature on the...

D. Kouvatsos J. G. Huang R. J. Jaccodine

1991-01-01

214

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

215

Oxidative coupling of methane on oxygen-semipermeable yttria-doped bismuth oxide ceramics in a reducing atmosphere  

SciTech Connect

Oxidative coupling of methane (OCM) on oxygen-semipermeable {delta}-phase 25 mol % Y{sub 2}O{sub 3}/Bi{sub 2}O{sub 3} (BY25) in a reducing (methane) atmosphere was studied by measuring transient catalytic properties and weight change of the ceramics when exposed to a methane stream at high temperatures (>800 C). Compared to the results obtained in a fixed-bed reactor operated in the cofeed mode, BY25 ceramics in a pellet form exhibit extremely high C{sub 2} selectivity (94%) and appreciable reactivity (C{sub 2} formation rate of 0.7 {micro}mol/g{center_dot}s) for OCM in a highly reducing methane atmosphere. Experimental results are also reported to show the effects of temperature, flow rate, methane exposure time, helium purge time, and helium to methane ratio on catalytic properties of BY25 pellets in a methane atmosphere. The results indicate that BY25 ceramic membrane materials possess desired catalytic properties for OCM membrane reactor applications.

Zeng, Y.; Lin, Y.S. [Univ. of Cincinnati, OH (United States). Dept. of Chemical Engineering] [Univ. of Cincinnati, OH (United States). Dept. of Chemical Engineering

1997-02-01

216

Study of the redox properties of bismuth-molybdate and uranium-antimonate catalysts  

Microsoft Academic Search

The oxidation\\/reduction properties of various bismuth molybdates, molybdenum trioxide, bismuth oxide, uranium antimonate, and iron antimonate have been studied in an effort to correlate them to their catalytic properties. The temperature at which ..gamma..-phase bismuth molybdate is prereduced plays an important role in the behavior the catalyst exhibits under reoxidation conditions. The overall behavior of ..gamma..-phase bismuth molybdate under catalytic

Paz-Pujalt

1985-01-01

217

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

218

Photoluminescence stabilization of anodically-oxidized porous silicon layers by chemical functionalization  

Microsoft Academic Search

Electrochemical oxidation of porous silicon (PSi) produces a surface that is covered with native silicon–hydrogen (Si–Hx) bonds and regions with oxidized Si–Si back-bonds (OSi–Hx). Such anodically oxidized PSi layers were chemically modified using 1-decene under thermal conditions. The hydrosilylation reaction consumes mainly the nonoxidized Si–Hx bonds and yields a surface with oxidized and alkylated regions that were characterized using transmission

Rabah Boukherroub; Danial D. M. Wayner; David J. Lockwood

2002-01-01

219

Photoluminescence stabilization of anodically-oxidized porous silicon layers by chemical functionalization  

Microsoft Academic Search

Electrochemical oxidation of porous silicon (PSi) produces a surface that is covered with native silicon-hydrogen (Si-Hx) bonds and regions with oxidized Si-Si back-bonds (OSi-Hx). Such anodically oxidized PSi layers were chemically modified using 1-decene under thermal conditions. The hydrosilylation reaction consumes mainly the nonoxidized Si-Hx bonds and yields a surface with oxidized and alkylated regions that were characterized using transmission

Rabah Boukherroub; Danial D. M. Wayner; David J. Lockwood

2002-01-01

220

Transparent conductive oxides for thin-film silicon solar cells  

NASA Astrophysics Data System (ADS)

This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses, the front TCO plays an important role for the light enhancement of thin-film silicon pin type solar cells. If the TCO is rough, light scattering at rough interfaces in the solar cell in combination with a highly reflective back contact leads to an increase in optical path length of the light. Multiple (total) internal reflectance leads to virtual 'trapping' of the light in the solar cell structure, allowing a further decrease in absorber thickness and thus thin-film silicon solar cell devices with higher and more stable efficiency. Here, the optical mechanisms involved in the light trapping in thin-film silicon solar cells have been studied, and two types of front TCO materials have been investigated with respect to their suitability as front TCO in thin-film silicon pin type solar cells. Undoped and aluminum doped zinc oxide layers have been fabricated for the first time by the expanding thermal plasma chemical vapour deposition (ETP CVD) technique at substrate temperatures between 150 º C and 350 º C, and successfully implemented as a front electrode material for amorphous silicon pin superstrate type solar cells. Solar cells with efficiencies comparable to cells on Asahi U-type reference TCO have been reproducibly obtained. A higher haze is needed for the ZnO samples studied here than for Asahi U-type TCO in order to achieve comparable long wavelength response of the solar cells. This is attributed to the different angular distribution of the scattered light, showing higher scattering intensities at large angles for the Asahi U-type TCO. A barrier at the TCO/p interface and minor collection problems may explain the slightly lower fill factors obtained for the cells on ETP ZnO. The solar cells deposited on the first doped ZnO:Al layers suffered from collection problems reducing the fill factor, and from shunting. This is attributed to the steep trenches, sharp features and vertical steps that have been identified at the TCO surface. ZnO:Al layers with granular structure, deposited at higher argon flow through the cascaded arc plasma source, allowed for fill factors of the solar cells up to 0.70, comparable to cells on undoped ZnO. The best solar cell on doped ZnO:Al deposited by ETP CVD achieved an efficiency of 9.3 % which is comparable to the 9.4 % obtained on Asahi U-type SnO2:F. Fluorinated tin oxide has been deposited by Atmospheric Chemical Vapor Deposition (APCVD) on glass from three different tin precursors, tetramethyltin, monobutyltin trichloride, and tin tetrachloride (TTC). TTC is the Sn precursor which resulted in the TCO with the best performance of a-Si:H pin solar cells. In accordance with the conclusions from our experiments with solar cells on undoped and aluminum doped zinc oxide, a high surface roughness and haze do not necessarily lead to a lower diode quality, and vice versa.

Löffler, J.

2005-04-01

221

Structural changes of oxide films during anodization of P doped silicon in aqueous ammonium fluoride  

Microsoft Academic Search

The growth and structural changes of the silicon dioxide film on boron doped silicon have been investigated during electrochemical oxidation in acidic ammonium fluoride solution. A high-speed spectroscopic ellipsometer was employed to obtain in-situ measurements while the silicon was subjected to anodic potential steps. These observations indicate that silicon dioxide does not dissolve in 0.10 M ammonium fluoride solution as

R. W. Crocker; R. H. Muller

1988-01-01

222

Effects of humidity on nano-oxidation of silicon nitride thin film  

Microsoft Academic Search

Effects of humidity on nanometer-scale oxidation of silicon nitride thin film using atomic force microscope in contact mode are studied at various values of relative humidity (RH) (30–70%). The shape of oxide protrusion is determined by the concentration of oxyanions under the tip apex and oxyanions diffusion laterally on the surface. At low RH (?60%), the kinetics of silicon nitride

Hsun-Feng Hsu; Chien-Wei Lee

2008-01-01

223

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 SRO–PECVD films, whereas in SRO–LPCVD films the IR spectra looked like the stoichiometric thermal silicon oxide. Moreover, X-ray photoelectron

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

2007-01-01

224

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

Microsoft Academic Search

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

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

2003-01-01

225

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

Microsoft Academic Search

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

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

2003-01-01

226

An oxidized porous silicon (OPS) microlens implemented on thick OPS membrane for a silicon-based optoelectronic-multichip module (OE-MCM)  

Microsoft Academic Search

Using the silicon bulk micromachining and selectively oxidized porous silicon (SOPS) technology, a silicon dioxide microlens was implemented on thick oxidized porous silicon (OPS) membrane. Because the surface of microlens was the interface of OPS-Si, the surface roughness of lens was directly affected by the anodization current density, substrate resistivity, and high-frequency percent in ethanol-contained electrolyte. In the SOPS technology,

Man-Lyun Ha; Jae-Ho Kim; Sung-Ku Yeo; Young-Se Kwon

2004-01-01

227

Conduction mechanism of oxide-nitride-oxide film formed on the rough polycrystalline silicon surface  

NASA Astrophysics Data System (ADS)

The conduction mechanism of oxide-nitride-oxide film formed on the rough polycrystalline silicon surface, which has non-uniform grain sizes, is studied. At the positive bias, Poole-Frenkel (PF) conduction of holes dominates in the total leakage current. At the negative bias, although the PF conduction of holes is dominant in the nitride, Fowler-Nordheim tunneling conduction of electrons also occurs at a higher electric field. This phenomenon is discussed with a model assuming an electric field concentration at the convex edge of the plate electrode, which is formed between neighboring grains.

Matsuo, Naoto; Sasaki, Akio

1996-03-01

228

Molecular Structure of Bismuth  

NSDL National Science Digital Library

Bismuth has been known since the early fifteenth century, but was often confused with lead and tin until Claude Geoffrey the Younger clearly proved its distinctiveness in 1753. Bismuth can be found as crystals of the native metal, but is most often obtained from metallurgical byproducts such as lead bullion from smelting of lead, silver, copper, or gold. Bismuth has the lowest thermal conductivity of all metals. Because bismuth melts at 545 degrees kelvin, it is used in low-melting alloys with tin and cadmium for such products as electric fuses, solder, and fire detectors. Bismuth is also used in pharmaceuticals, medicine, and cosmetics such as lipstick and eye polish.

2003-04-10

229

Efficient and sustained photoelectrochemical water oxidation by cobalt oxide/silicon photoanodes with nanotextured interfaces.  

PubMed

Plasma-enhanced atomic layer deposition of cobalt oxide onto nanotextured p(+)n-Si devices enables efficient photoelectrochemical water oxidation and effective protection of Si from corrosion at high pH (pH 13.6). A photocurrent density of 17 mA/cm(2) at 1.23 V vs RHE, saturation current density of 30 mA/cm(2), and photovoltage greater than 600 mV were achieved under simulated solar illumination. Sustained photoelectrochemical water oxidation was observed with no detectable degradation after 24 h. Enhanced performance of the nanotextured structure, compared to planar Si, is attributed to a reduced silicon oxide thickness that provides more intimate interfacial contact between the light absorber and catalyst. This work highlights a general approach to improve the performance and stability of Si photoelectrodes by engineering the catalyst/semiconductor interface. PMID:24720554

Yang, Jinhui; Walczak, Karl; Anzenberg, Eitan; Toma, Francesca M; Yuan, Guangbi; Beeman, Jeffrey; Schwartzberg, Adam; Lin, Yongjing; Hettick, Mark; Javey, Ali; Ager, Joel W; Yano, Junko; Frei, Heinz; Sharp, Ian D

2014-04-30

230

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.

231

Investigation of PEMFC operation above 100 °C employing perfluorosulfonic acid silicon oxide composite membranes  

NASA Astrophysics Data System (ADS)

Various perfluorosulfonic acid membranes (PFSAs) were studied as pure and silicon oxide composite membranes for operation in hydrogen/oxygen proton-exchange membrane fuel cells (PEMFCs) from 80 to 140 °C. The composite membranes were prepared either by impregnation of pre-formed PFSAs via sol-gel processing of a polymeric silicon oxide, recasting a film using solubilized PFSAs and a silicon oxide polymer/gel. All composite membranes had a silicon oxide content of less than or equal to 10% by weight. Decreasing the equivalent weight and thickness of the PFSAs, in addition to the incorporation of silicon oxide helped improve water management in a PEMFC at elevated temperatures. Fourier transform-infrared spectroscopy-attenuated total reflectance (FT-IR-ATR), and scanning electron microscopy (SEM) experiments indicated an evenly distributed siloxane polymer in all of the composite membranes. At a potential of 0.4 V the Aciplex 1004/silicon oxide composite membrane in a humidified H 2/O 2 PEMFC at 130 °C and a pressure of 3 atm delivered six times higher current density than unmodified Nafion 115 under the same conditions, and 1.73 times the current density when unmodified Nafion 115 was operated with humidified gases at 80 °C and 1 atm of pressure. Furthermore, the PEMFC performances with the PFSA/silicon oxide composite membranes were physically more robust than the control membranes (unmodified PFSAs), which degraded after high operation temperature and thermal cycling.

Adjemian, K. T.; Srinivasan, S.; Benziger, J.; Bocarsly, A. B.

232

Microbridge testing of plasma-enhanced chemical-vapor deposited silicon oxide films on silicon wafers  

NASA Astrophysics Data System (ADS)

Plasma-enhanced chemical-vapor deposited (PECVD) silane-based oxides (SiOx) have been widely used in both microelectronics and microelectromechanical systems (MEMS) to form electrical and/or mechanical components. In this paper, a nanoindentation-based microbridge testing method is developed to measure both the residual stresses and Young's modulus of PECVD SiOx films on silicon wafers. Theoretically, we considered both the substrate deformation and residual stress in the thin film and derived a closed formula of deflection versus load. The formula fitted the experimental curves almost perfectly, from which the residual stresses and Young's modulus of the film were determined. Experimentally, freestanding microbridges made of PECVD SiOx films were fabricated using the silicon undercut bulk micromachining technique. Some microbridges were subjected to rapid thermal annealing (RTA) at a temperature of 400 °C, 600 °C, or 800 °C to simulate the thermal process in the device fabrication. The results showed that the as-deposited PECVD SiOx films had a residual stress of -155+/-17 MPa and a Young's modulus of 74.8+/-3.3 GPa. After the RTA, Young's modulus remained relatively unchanged at around 75 GPa, however, significant residual stress hysteresis was found in all the films. A microstructure-based mechanism was then applied to explain the experimental results of the residual stress changes in the PECVD SiOx films after the thermal annealing.

Cao, Zhiqiang; Zhang, Tong-Yi; Zhang, Xin

2005-05-01

233

Internal charge distribution of iodine adatoms on silicon and silicon oxide investigated with alkali ion scattering  

NASA Astrophysics Data System (ADS)

Time-of-flight spectra were collected for low energy 7Li + and 23Na + ions backscattered from Si(1 1 1) surfaces covered with sub-monolayers of iodine. Li ions singly scattered from the iodine adatoms have consistently larger neutralization probabilities than those scattered from the silicon substrate, and the neutralization decreases with off-normal emission. This indicates that the internal charge distribution of the iodine adatoms is not uniform, presumably due to attraction of electron density to the positively charged bonding Si atom. Photoelectron spectroscopy shows that iodine adsorbed on pre-oxidized Si bonds through the oxygen atom, forming hypoiodite (-OI) moieties. The neutralization of 23Na + backscattered from such iodine adatoms is independent of the emission angle, indicating that there is less charge rearrangement than for iodine bonded directly to Si.

Yang, Ye; Yarmoff, Jory A.

2004-12-01

234

Synthesis conductivity, and X-ray photoelectron spectrum of Bi sub 2 Sr sub 2 Cu sub 7+X. A new ternary bismuth-oxide system exhibiting metallic conductivity  

SciTech Connect

The preparation and some of the properties relating to the superconductive state of the newly discovered ternary bismuth oxides, Bi{sub 2}Sr{sub 2}Cu{sub 2}O{sub 7+x}, are described. Conductivity behavior ranging from semiconductive to metallic is observed when four-probe. AC resistivity measurements are carried out on pressed pellet specimens that have been annealed under different conditions. From a determination of the total oxygen present by an iodometric titration, it was found that metallic conductivity was associated with a higher oxygen content. An X-ray photoelectron experiment was carried out in order to determine whether bismuth or copper was present as the mixed-valent species. The XPS spectrum of the Bi 4f orbital electrons in the oxides was nearly identical to that observed in Bi{sub 2}O{sub 3}, with no evidence of any Bi{sup 5+}. 8 refs., 3 figs.

Porter, L.C.; Appleman, E.; Beno, M.A.; Cariss, C.S.; Carlson, K.D.; Cohen, H.; Geiser, U.; Thorn, R.J.; Williams, J.M.

1989-01-01

235

Bismuth + metronidazole + tetracycline. Why risk adding bismuth?  

PubMed

The standard treatment for peptic ulcer associated with Helicobacter pylori is a combination of omeprazole, amoxicillin and clarithromycin, which renders the bacterium undetectable in about 70% of cases. A fixed-dose combination of bismuth subcitrate potassium + metronidazole + tetracycline has been authorised in some European countries for use in this setting, combined with high-dose omeprazole. In a European trial with 440 patients, the 4-drug combination of omeprazole + bismuth subcitrate + metronidazole + tetracycline was significantly more active than the standard 3-drug regimen in terms of H. pylori eradication, as measured with the urea breath test (79.8% with bismuth, 55.4% without bismuth). In a North American trial with 275 patients the success rate was similar with the two treatments, again based on the urea breath test. There are no comparative trials of the 4-drug regimen in patients in whom standard treatment has failed. The main adverse effects of the 4-drug regimen observed in clinical trials were black stools, nausea, headache and dizziness. However, the trials were too small to detect infrequent but serious adverse effects such as bismuth encephalopathy. Safety during pregnancy is not known. Some patients included in clinical trials had detectable plasma bismuth concentrations. Omeprazole increases the absorption of bismuth subcitrate potassium. In practice, the 4-drug regimen combining omeprazole + bismuth subcitrate potassium + metronidazole + tetracycline is probably more effective than standard 3-drug therapy against H. pylori, at least in Europe, but this combination should be avoided due to uncertainties on the possible neurotoxicity of bismuth. Other antibiotic combinations are preferable, and there are too many questions surrounding the adverse effects of this combination for it to replace the standard 3-drug regimen in France. PMID:23662315

2013-04-01

236

Heteroepitaxy and dry oxidation of silicon-germanium and silicon-germanium-carbon alloy thin films on silicon(100)  

NASA Astrophysics Data System (ADS)

Heteroepitaxial silicon-germanium (Si1-xGex) alloys have found applications in Si-based technology. However, a good quality dielectric on Si1-xGex cannot be obtained by thermal oxidation. The goal of this study is to investigate the effect of carbon incorporation upon epitaxial growth and thermal oxidation of Si1-xGex alloys and its role on strain compensation in Si1-xGex alloys. Both binary silicon-germanium (Si1-xGex) and ternary silicon-germanium-carbon (Si1-x-yGexCy) alloys with similar Si/Ge ratio are grown by Combined Ion and Molecular beam Deposition (CIMD) on P-type Si (100) substrate and compared. Prior to the epitaxial growth, a unique passivation technique is used to provide an ultra-clean and ultra-smooth Si (100) surface at low temperature. It involves a "modified RCA-type" pre-cleaning followed by HF/Methanol passivation and in situ thermal cleaning at a low temperature. As-deposited epitaxial films are then oxidized at three different temperatures by rapid thermal oxidation and furnace dry oxygen. The composition, structure, crystalline quality and surface morphology of binary and ternary alloys before and after oxidation are compared using a combination of Rutherford Backscattering Spectrometry (RBS) and ion channeling at 2.0 MeV, carbon Nuclear Resonance Analysis (NRA) at 4.3 MeV with 4He++ ions, Secondary Ion-Mass Spectrscopy (SIMS), Tapping Mode Atomic Force Microscopy (TMAFM), High-Resolution Transmission Electron Microscopy (HRTEM), and Fourier Transformation Infrared (FTIR) spectroscopy. The study demonstrates that the hydroxide passivated Si (100) surface obtained by our passivation technique yields exceptionally smooth and ordered (1x1) Si (100) surfaces at room temperature, and ultra-smooth (2x1) ordering after in situ low temperature desorption. We show that it is difficult to grow Si1-x-yGexC y films with quality comparable to binary Si1-xGex. Instead our results indicate a lower barrier to defect formation in Si 1-x-yGexCy than in Si1-xGex. We find that a growth temperature lower than 560°C is necessary to avoid the precipitation of a precursor phase to SiC in Si and in Si1-xGe x matrix, akin to Guinier Preston zones in the growth conditions used. The Si1-x-yGexCy films are considerably rougher than the Si1-xGex films of similar Si/Ge fractions. Roughness increases with increasing C fraction, indicating that the introduction of C lowers the barrier for the onset of Stranski-Krastanov type growth. The importance of an independent and accurate measurement of the total and substitutional C fraction within the films is shown. This study also demonstrates the importance of using a combination of different analysis techniques for film characterization. Dry oxidation of (Si1-xGex) and Si1-x-yGe xCy thin films leads to the formation of a conformal SiO 2 layer on the top surface, while Ge segregates towards the top surface and at the SiO2/Si1-xGex and SiO2/Si 1-x-yGexCy interfaces, in agreement with previous findings. However, we report the first time observation that dry oxidation rates in (Si1-xGex) decrease with increasing Ge fraction x for x > 0.20 and with increasing film minimum yield. Ion channeling analysis and strain measurements indicate that the incorporation of C rather than the amount of C itself affects the dry oxidation mechanism. Dry oxidation relaxes the previously strained (Si1-xGex) making the films more defective with a rougher surface. This is in contrast to the oxidation of Si (100) where oxidation always has a planarization effect. For relaxed Si1-xGex and defective Si1-x-yGexC y, dry oxidation does not have significant effect on the film crystalline quality and on the surface morphology.

Xiang, Jiong

2000-10-01

237

Effect of antimony and bismuth on the electrochemical corrosion of cast aluminum–silicon alloys in 3% NaCl solution  

Microsoft Academic Search

The corrosion behavior of Al–Si–Bi (to 0.5 wt.% Bi) and Al–Si–Sb (to 0.5 wt.% Sb) ternary alloys is studied with polarization\\u000a curves and scanning electron microscopy in 3% NaCl solution. The current density decreases with doping content to 0.05 wt.%\\u000a and, thus, the corrosion rate slows down. With greater contents of antimony and bismuth, the current density of initial passivation

M. O. Krasovskii; V. O. Lavrenko

2011-01-01

238

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

239

Improved electrical and reliability characteristics in metal/oxide/nitride/oxide/silicon capacitors with blocking oxide layers formed under the radical oxidation process.  

PubMed

We propose a Metal-Oxide-Nitride-Oxide-Silicon (MONOS) structure whose blocking oxide is formed by radical oxidation on the silicon nitride (Si3N4) layer to improve the electrical and reliability characteristics. We directly compare the electrical and reliability properties of the MONOS capacitors with two different blocking oxide (SiO2) layers, which are called a "radical oxide" grown by the radical oxidation and a "CVD oxide" deposited by chemical vapor deposition (CVD) respectively. The MONOS capacitor with a radical oxide shows a larger C-V memory window of 3.6 V at sweep voltages from 9 V to -9 V, faster program/erase speeds of 1 micros/1 ms at bias voltages of -6 V and 8 V, a lower leakage current of 7 pA and a longer data retention, compared to those of the MONOS capacitor with a CVD oxide. These improvements have been attributed to both high densification of blocking oxide film and increased nitride-related memory traps at the interface between the blocking oxide and Si3N4 layer by radical oxidation. PMID:21128482

An, Ho-Myoung; Kim, Hee Dong; Seo, Yu Jeong; Kim, Kyoung Chan; Sung, Yun Mo; Koo, Sang-Mo; Koh, Jung-Hyuk; Kim, Tae Geun

2010-07-01

240

High-temperature oxidation behavior of reaction-formed silicon carbide ceramics  

NASA Technical Reports Server (NTRS)

The oxidation behavior of reaction-formed silicon carbide (RFSC) ceramics was investigated in the temperature range of 1100 to 1400 C. The oxidation weight change was recorded by TGA; the oxidized materials were examined by light and electron microscopy, and the oxidation product by x-ray diffraction analysis (XRD). The materials exhibited initial weight loss, followed by passive weight gain (with enhanced parabolic rates, k(sub p)), and ending with a negative (logarithmic) deviation from the parabolic law. The weight loss arose from the oxidation of residual carbon, and the enhanced k(sub p) values from internal oxidation and the oxidation of residual silicon, while the logarithmic kinetics is thought to have resulted from crystallization of the oxide. The presence of a small amount of MoSi, in the RFSC material caused a further increase in the oxidation rate. The only solid oxidation product for all temperatures studied was silica.

Ogbuji, Linus U. J. T.; Singh, M.

1995-01-01

241

Microstructure evolution during silicon oxidation at room temperature under composite ion beam irradiation  

NASA Astrophysics Data System (ADS)

In this work, we studied the silicon microstructure evolution during its oxidation under composite beam ion irradiation at room temperature. It was found that when the composite ion beam was formed by hydrogen and dry oxygen mixture at low doses (˜1018 cm?2), a porous silicon layer was formed. During irradiation, the pore size gradually reduced and at a dose of ˜1020 cm?2 pores disappear completely, and an uniform layer of silicon oxide was formed. If residual gases and hydrogen are used to generate a composite ion beam, the formation of porous silicon is not found. The final thickness of irradiation-induced silicon oxide corresponded to the projected range of protons at a given energy in both cases.

Prikhodko, K. E.; Gurovich, B. A.; Komarov, D. A.; Goncharova, D. A.; Kutuzov, L. V.

2014-05-01

242

Chemical properties of oxidized silicon carbide surfaces upon etching in hydrofluoric acid.  

PubMed

Hydrogen termination of oxidized silicon in hydrofluoric acid results from an etching process that is now well understood and accepted. This surface has become a standard for studies of surface science and an important component in silicon device processing for microelectronics, energy, and sensor applications. The present work shows that HF etching of oxidized silicon carbide (SiC) leads to a very different surface termination, whether the surface is carbon or silicon terminated. Specifically, the silicon carbide surfaces are hydrophilic with hydroxyl termination, resulting from the inability of HF to remove the last oxygen layer at the oxide/SiC interface. The final surface chemistry and stability critically depend on the crystal face and surface stoichiometry. These surface properties affect the ability to chemically functionalize the surface and therefore impact how SiC can be used for biomedical applications. PMID:19919146

Dhar, Sarit; Seitz, Oliver; Halls, Mathew D; Choi, Sungho; Chabal, Yves J; Feldman, Leonard C

2009-11-25

243

Hybrid organic light emitting device with silicon-rich oxide as hole transporting layer  

Microsoft Academic Search

In order to combine both advantages of organic and inorganic materials and to solve the problem of mobility mismatch between hole transport layer (e.g. NPB) and electron transport layer (e.g. AlQ) of organic light emitting diodes, a mobility-tunable HTL of silicon-rich silicon oxide (Si1+xO2) is proposed. By changing the degree of excess silicon x, the mobility of Si1+xO2 can be

G. Z. Ran; D. F. Jiang; Y. Yin; W. J. Xu

2011-01-01

244

Organic Matter and Silicon in Relation to the Crystallinity of Soil Iron Oxides  

Microsoft Academic Search

The contents of pyrophosphate-extractable carbon and iron, EDTA-extractable iron, dithionite-EDTA-extractable iron and silicon, total carbon, and sodium hydroxide-extractable silicon were determined in thirty soil samples from Denmark and Tanzania in order to investigate the general influence of organic matter and silicon on the crystallinity of soil iron oxides. The ratio between the contents of EDTA-extractable iron and dithionite-EDTA-extractable iron, both

Ole K. Borggaard

1985-01-01

245

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

246

Characteristics of polycrystalline silicon thin-film transistors with thin oxide/nitride gate structures  

NASA Astrophysics Data System (ADS)

Polycrystalline silicon (poly-Si) thin-film transistors (TFTs) with thin oxide/nitride (O/N) structures as gate dielectrics are fabricated. Various gate dielectrics, i.e., high-temperature thermal oxides with different thicknesses, low-pressure chemical-vapor-deposited silicon nitrides, and different combinations of O/N structures with various thicknesses, are performed to study their effects on poly-Si TFTs. The effective carrier mobility of devices with thin gate oxides is several times larger than of those with thick gate oxides. However, the breakdown voltages of thin gate oxides are too low to satisfy the requirements of TFT applications. Silicon nitrides can be substituted because of the high breakdown voltage and the smooth dielectric/poly-Si interfaces. A problem in adopting silicon nitride is the large interface stress between the silicon nitride and the poly-Si. A thin thermal pad oxide beneath the silicon nitride is therefore grown to reduce the high interface stress. Finally, the equivalent oxide thickness effect of the O/N gate structures on the electrical characteristics of TFTs is systematically investigated.

Cheng, Huang-Chung; Tai, Ya-Hsiang; Feng, Ming-Shiann; Wang, Jau-Jey

1993-08-01

247

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

248

High-temperature oxidation behavior of hot-dipped aluminide mild steel with various silicon contents  

NASA Astrophysics Data System (ADS)

Mild steel was coated by hot-dipping into molten baths containing pure aluminum, Al-2.5Si, Al-5Si and Al-10Si (wt.%) at 700 °C for 180 s. Isothermal and cyclic oxidations were carried out at 750 °C in static air to study the oxidation behavior of the hot-dipped aluminide steel with various silicon contents. The results of isothermal oxidation show the weight gains of the aluminide steel followed a parabolic law. The isothermal oxidation rates of the aluminide steel specimens were directly proportional to the silicon content in the aluminide layers. The reason for the aluminide steel with high silicon possessing a high isothermal oxidation rate is that the silicon addition in the molten bath caused a reduction in the aluminide layer thickness and the formation of phase transformation induced voids in the aluminide layer. The results, after cyclic oxidation, show the weight gains of the aluminide steel specimens were larger than those after isothermal oxidation. Because the aluminide layer with low silicon was mainly composed of a thick brittle Fe2Al5 phase, thermal stress was easily generated in the aluminide layer and caused the formation of vertical cracks when the aluminide steel underwent cyclic oxidation. Once cracks appeared, the weight gains of the aluminide steel specimens were accelerated. Thus, mild steel after hot-dipping in pure aluminum, which had the thickest Fe2Al5 layer, possessed the worst resistance to cyclic oxidation.

Cheng, Wei-Jen; Wang, Chaur-Jeng

2013-06-01

249

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

250

Modeling and experimental validation of sharpening mechanism based on thermal oxidation for fabrication of ultra-sharp silicon nanotips  

Microsoft Academic Search

This paper aims at modeling the thermal oxidation of silicon pillars leading to the formation of very sharp silicon tips. The model is used to determine optimum process parameters with respect to the initial shape of the silicon pillars and the geometry of the desired tip. The modeling concept is to extend a previous approach, which predicts the oxidation mechanism

Vincent Agache; Roger Ringot; Patrice Bigotte; Vincent Senez; Bernard Legrand; Lionel Buchaillot; Dominique Collard

2005-01-01

251

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

252

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

SciTech Connect

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 semiconductors.

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

1999-07-21

253

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; Martínez, J; García, R

2009-11-25

254

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

Microsoft Academic Search

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 semiconductors.

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

1999-01-01

255

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

DOEpatents

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

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

1984-03-13

256

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

NASA Astrophysics Data System (ADS)

In this paper, the simple pre-oxidization process is firstly used to treat the starting silicon wafer, and then MPSiNWs are successfully fabricated from the moderately doped wafer by one-step MACE technology in HF/AgNO3 system. The PL spectrum of MPSiNWs obtained from the oxidized silicon wafers show a large blue-shift, which can be attributed to the deep Q. C. effect induced by numerous mesoporous structures. The effects of HF and AgNO3 concentration on formation of SiNWs were carefully investigated. The results indicate that the higher HF concentration is favorable to the growth of SiNWs, and the density of SiNWs is significantly reduced when Ag+ ions concentrations are too high. The deposition behaviors of Ag+ ions on oxidized and unoxidized silicon surface were studied. According to the experimental results, a model was proposed to explain the formation mechanism of porous SiNWs by etching the oxidized starting silicon.

Li, Shaoyuan; Ma, Wenhui; Zhou, Yang; Chen, Xiuhua; Xiao, Yongyin; Ma, Mingyu; Wei, Feng; Yang, Xi

2014-05-01

257

High aspect ratio silicon pillars fabricated by electrochemical etching and oxidation of macroporous silicon  

Microsoft Academic Search

A technique for fabricating sub-micron free-standing silicon pillars has been developed. The silicon pillars have a high packing density, and aspect ratios over 50:1 can easily be achieved. Silicon wafers of 3–5 ? cm resistivity is patterned with regular windows on a silicon nitride layer by conventional photolithography. Inverted pyramids are formed within the windows after orientation-dependent KOH etching. During

H. W Lau; G. J Parker; R Greef

1996-01-01

258

Dielectric properties of oxidized porous silicon in a low resistivity substrate  

Microsoft Academic Search

Oxidized porous silicon (OPS) is characterized for its high frequency electrical properties up to 50 GHz. Transmission line properties are determined from measurement data and are compared with high and low resistivity silicon benchmark designs. Best OPS performance of 50 Ohm lines is observed on oxide-capped OPS, having attenuation of approximately 2.93 dB\\/cm at 4 GHz with an effective dielectric

Rebecca L. Peterson; Rhonda F. Drayton

2001-01-01

259

Reversible photochromic effects in doped single crystals of bismuth germanium (Bi12GeO20) and bismuth silicon oxide (Bi12SiO20)  

Microsoft Academic Search

Absorption of Bi12GeO20 and Bi12SiO20 single crystals doped with Mn and Cr were investigated before and after illumination with visible light. Pronounced photochromic effects were found. The effects are explained in terms of light induced charge transfer Mn4+-->Mn5+ and Cr3+-->Cr2+.

W. Wardzynski; T. Lukasiewicz; J. Zmija

1979-01-01

260

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

261

The influence of natural and stimulated oxidation on luminescent properties of silicon-cellulose nanocomposites  

NASA Astrophysics Data System (ADS)

A composite has been developed on the basis of nanocrystalline cellulose and silicon nanoparticles, which exhibited more intense photoluminescence in the visible range of the spectrum than did nanoporous silicon. This may be related to the spatial separation of silicon nanoparticles and migration of excitation from their vicinity. The effect of temperature and gas-phase oxidation on the luminescent properties of the material indicates a high stability of the luminescent properties of the composite. Investigation of the charging effect of the nanocomposite allows silicon nanoparticles to be considered as centers of accumulation of the bulk electricity charge.

Pikulev, V. B.; Loginova, S. V.; Gurtov, V. A.

2012-08-01

262

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

Microsoft Academic Search

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

Jinling Yang; João Gaspar; Oliver Paul

2008-01-01

263

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

264

Thromboresistance Characterization of Extruded Nitric Oxide-Releasing Silicone Catheters  

PubMed Central

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/cm2 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.

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

2013-01-01

265

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

266

Process for depositing an oxide epitaxially onto a silicon substrate and structures prepared with the process  

DOEpatents

A process and structure involving a silicon substrate utilizes an ultra high vacuum and molecular beam epitaxy (MBE) methods to grow an epitaxial oxide film upon a surface of the substrate. As the film is grown, the lattice of the compound formed at the silicon interface becomes stabilized, and a base layer comprised of an oxide having a sodium chloride-type lattice structure grows epitaxially upon the compound so as to cover the substrate surface. A perovskite may then be grown epitaxially upon the base layer to render a product which incorporates silicon, with its electronic capabilities, with a perovskite having technologically-significant properties of its own.

McKee, Rodney A. (Kingston, TN); Walker, Frederick J. (Oak Ridge, TN)

1993-01-01

267

Electrical conduction and dielectric breakdown in aluminum oxide insulators on silicon  

Microsoft Academic Search

Leakage currents and dielectric breakdown were studied in MIS capacitors of metal-aluminum oxide-silicon. The aluminum oxide was produced by thermally oxidizing AlN at 800-1160°C under dry O2 conditions. The AlN films were deposited by RF magnetron sputtering on p-type Si (100) substrates. Thermal oxidation produced Al 2O3 with a thickness and structure that depended on the process time and temperature.

James Kolodzey; Enam Ahmed Chowdhury; Thomas N. Adam; Guohua Qui; I. Rau; J. O. Olowolafe; J. S. Suehle; Yuan Chen

2000-01-01

268

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 400°C and 300°C 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 600°C, which is 100°C higher than on the other silicon surfaces. When HfO2 is grown on H/Si(111) at 100°C 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

269

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

270

Surface morphology and structure of ultra-thin magnesium oxide grown on (100) silicon by atomic layer deposition oxidation  

Microsoft Academic Search

Ultra-thin magnesium oxide layers were elaborated by atomic layer deposition and oxidation process on silicon (100) starting from (2×1) thermally-reconstructed or hydrogen-terminated Si surfaces. Low-energy electron diffraction experiments show (2×3) and (3×3) reconstructions while depositing a magnesium monolayer on Si clean surfaces, and a 3-dimentional growth of the oxide as confirmed by ex-situ atomic force microscopy. For hydrogen-terminated or clean

N. Rochdi; K. Liudvikouskaya; M. Descoins; M. Raïssi; C. Coudreau; J.-L. Lazzari; H. Oughaddou; F. Arnaud D'Avitaya

2011-01-01

271

Enhanced photoresponse of a metal-oxide-semiconductor photodetector with silicon nanocrystals embedded in the oxide layer  

Microsoft Academic Search

The authors report a two-terminal metal-oxide-semiconductor photodetector for which light is absorbed in a capping layer of silicon nanocrystals embedded in a mesoporous silica matrix on p-type silicon substrates. Operated at reverse bias, enhanced photoresponse from 300 to 700 nm was observed. The highest optoelectronic conversion efficiency is as high as 200%. The enhancements were explained by a transistorlike mechanism,

Jia-Min Shieh; Yi-Fan Lai; Wei-Xin Ni; Hao-Chung Kuo; Chih-Yao Fang; Jung Y. Huang; Ci-Ling Pan

2007-01-01

272

Characterization of polycrystalline silicon-oxide-nitride-oxide-silicon devices on a SiO2 or Si3N4 buffer layer  

NASA Astrophysics Data System (ADS)

Silicon-oxide-nitride-oxide-silicon (SONOS) memory devices were fabricated from polycrystalline silicon (poly-Si) using the solid phase crystallization (SPC) method for use in a low-power system-on-panel (SOP) display. In these poly-Si SONOS memories, oxide or nitride was used as a buffer layer. The electrical characteristics, such as the threshold voltage ( V T ), subthreshold slope ( SS) and transconductance ( g m ), were determined for each SONOS device. To interpret the characteristics of both poly-Si devices, x-ray diffraction (XRD) measurements and flicker noise analysis were conducted. The results show that the poly-Si SONOS on the oxide layer has better electrical, memory characteristics, such as turn-on speed and g m , program/erase, endurance and data retention than that on the nitride layer. From the XRD measurements, it is shown that the grain size of the poly-Si on the oxide layer is larger than that on the nitride layer. From the flicker noise analysis, the poly-Si device on oxide was shown to have less traps or defects in the channel layer than that on nitride.

Lee, Sang-Youl; Oh, Jae-Sub; Yang, Seung-Dong; Yun, Ho-Jin; Jeong, Kwang-Seok; Kim, Yu-Mi; Lee, Hi-Deok; Lee, Ga-Won

2013-10-01

273

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] [Univ. of California, San Diego, CA (United States). Dept. of Chemistry and Biochemistry

1998-06-29

274

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

275

Gas-phase formation of silicon carbides, oxides, and sulphides from atomic silicon ions  

NASA Technical Reports Server (NTRS)

A systematic experimental study of the kinetics and mechanisms of the chemical reactions in the gas phase between ground-state Si(+)2p and a variety of astrophysical molecules. The aim of this study is to identify the reactions which trigger the formation of chemical bonds between silicon and carbon, oxygen and sulphur, and the chemical pathways which lead to further molecular growth. Such knowledge is valuable in the identification of new extraterrestrial silicon-bearing molecules and for an assessment of the gas-phase transition from atomic silicon to silicon carbide and silicate grain particles in carbon-rich and oxygen-rich astrophysical environments.

Bohme, Diethard K.; Wlodek, Stanislaw; Fox, Arnold

1989-01-01

276

Fabrication of low-loss silicon-on-oxidized-porous-silicon strip waveguide using focused proton-beam irradiation.  

PubMed

We have successfully fabricated low-loss silicon-on-oxidized-porous-silicon (SOPS) strip waveguides with high-index contrast using focused proton-beam irradiation and electrochemical etching. Smooth surface quality with rms roughness of 3.1 nm is achieved for a fluence of 1x10(15)/cm(2) after postoxidation treatment. Optical characterization at a wavelength of 1550 nm shows a loss of 1.1+/-0.4 dB/cm and 1.2+/-0.4 dB/cm in TE and TM polarization respectively, which we believe is the lowest reported loss for SOPS waveguides. This opens up new opportunities for all-silicon-based optoelectronics applications. PMID:19252584

Teo, E J; Bettiol, A A; Yang, P; Breese, M B H; Xiong, B Q; Mashanovich, G Z; Headley, W R; Reed, G T

2009-03-01

277

High density and large area arrays of silicon oxide pillars with tunable domain size for mask etch applications.  

PubMed

Silicon oxide pillars with tunable feature sizes and pitches are fabricated based on a block copolymer self-assembly template. By using reactive ion etching (RIE), the feature size of the silicon oxide pillars can be tuned without affecting the pitch. Using BCP with a different molecular weight can change the pitch size of the silicon oxide pillars. An area density of up to 2 teradots/inch(2) is achieved. PMID:22887113

Gu, Xiaodan; Dorsey, Paul; Russell, Thomas P

2012-10-23

278

Efficient indium tin oxide\\/polycrystalline silicon solar cells  

Microsoft Academic Search

ITO\\/Si-N solar cells have been fabricated by a spraying process at 500 C on polycrystalline silicon. Electroless nickel plating was used for the back Ohmic contact deposition. Electrical characteristics and spectra response of these heterojunctions are compared to those obtained on monocrystalline silicon. AM1 efficiency of approximately 9 percent (based on active area) is achieved for polycrystalline material. Temperature dependence

J. P. Schunck; A. Coche

1979-01-01

279

The Impact Of Organic Contamination On The Oxide-Silicon Interface  

NASA Astrophysics Data System (ADS)

This paper collects the results of a study aimed to investigate the impact of organic contamination on the electrical properties of the silicon oxide and of the silicon oxide-silicon interface. Some wafers were contaminated by immersion in solution of diethylphthalate (DEP) in solvent. The wafers were then oxidized to perform surface recombination velocity measurements by Elymat, and capacitors were fabricated for capacitance vs. voltage and capacitance vs time measurements. In addition, the interface state density was measured by the MOS-DLTS technique and the gate oxide integrity was evaluated by constant current stress. Elymat measurements of surface recombination velocity show that surface recombination velocity is increased by organic contamination. From the point-of-view of the intrinsic properties of the silicon oxide-silicon interface, MOS-DLTS showed the most significant effects. These measurements allowed identifying a band of interface states located around Ev +0.1 eV as related to organic contamination. However, the most relevant effects of organic contamination were observed by electrical stress of the oxide. Indeed, the fraction of capacitors with degraded breakdown voltage increased dramatically in contaminated wafers.

Codegoni, D.; Polignano, M. L.; Castellano, L.; Borionetti, G.; Bonoli, F.; Nutsch, A.; Leibold, A.; Otto, M.

2011-11-01

280

MOS junction based nanostructures by thermal oxidation of silicon wires for hydrogen detection  

Microsoft Academic Search

Heavily p-doped monocrystalline silicon wires have been fabricated by employing wet etch and thermal oxidation steps to achieve a nanometric cross-section; a gate oxide growth and a final palladium evaporation made up the MOS junction able to detect hydrogen concentrations in air.

A. Tibuzzi; M. Decarli; G. Soncini; C. Di Natale; A. D'Amico; B. Margesin; M. Zen

2003-01-01

281

Silicon-based microfabricated tin oxide gas sensor incorporating use of Hall effect measurement  

Microsoft Academic Search

Characterization of a microfabricated sol-gel derived nano-particle tin oxide thin film on a silicon substrate, through simultaneous measurement of conductivity, Hall mobility and electron density, had not been accomplished before this study. Conductivity is a function of carrier density and Hall mobility. Therefore, a full understanding of the sensing mechanism of tin oxide requires knowledge of the sensor conductivity, electron

Joseph Wilson Hammond

2000-01-01

282

A Note on the High-Temperature Oxidation of Chlorophenylmethyl Silicone Fluids.  

National Technical Information Service (NTIS)

The results of oxidation tests at a temperature of 250 C are described for two chlorophenylmethyl silicones intended for use as high temperature aircraft hydraulic fluids. It is shown that the extent and mode of oxidation may be significantly affected by ...

G. H. Kinner

1966-01-01

283

Nano-Scale Features in and on Silicon Formed using Anodic Alumina Oxide Templates  

Microsoft Academic Search

Nano-scale trenches and dots have been fabricated in and on silicon using masks based on anodic alumina oxide (AAO) templates formed by electrochemically oxidizing aluminum. Under the appropriate anodizing conditions, the AAO templates can form ordered hexagonal arrays of pores with tunable diameters and pore spacings. Typical parameters for an ordered porous alumina film formed in an oxalic acid electrolyte

P. R. Larson; A. M. Elliott; M. B. Johnson; M. Keil

2001-01-01

284

Optical absorption enhancement in 3D silicon oxide nano-sandwich type solar cell.  

PubMed

Recent research in the field of photovoltaic and solar cell fabrication has shown the potential to significantly enhance light absorption in thin-film solar cells by using surface texturing and nanostructure coating techniques. In this paper, for the first time, we propose a new method for nano sandwich type thin-film solar cell fabrication by combining the laser amorphization (2nd solar cell generation) and laser nanofibers generation (3rd solar cell generation) techniques. In this novel technique, the crystalline silicon is irradiated by megahertz frequency femtosecond laser pulses under ambient conditions and the multi-layer of amorphorized silicon and nano fibrous layer are generated in the single-step on top of the silicon substrate. Light spectroscopy results show significant enhancement of light absorption in the generated multi layers solar cells (Silicon Oxide nanofibers / thin-film amorphorized silicon). This method is single step and no additional materials are added and both layers of the amorphorized thin-film silicon and three-dimensional (3D) silicon oxide nanofibrous structures are grown on top of the silicon substrate after laser irradiation. Finally, we suggest how to maximize the light trapping and optical absorption of the generated nanofibers/thin-film cells by optimizing the laser pulse duration. PMID:24921988

Kiani, Amirkianoosh; Venkatakrishnan, Krishnan; Tan, Bo

2014-01-13

285

First-principles study of the mechanical and optical properties of amorphous hydrogenated silicon and silicon-rich silicon oxide  

NASA Astrophysics Data System (ADS)

We use first-principles density-functional theory (DFT) calculations to predict mechanical and optical property variation with composition for hydrogenated amorphous Si (a-Si:H) ( at.%H=0 , 5.9, 11.1, and 15.8) and a-SiOx ( x=0 , 0.5, 1.0, 1.5, and 2.0). A better understanding of the properties of a-Si:H and amorphous silicon oxide (a-SiOx) is technologically important, particularly for photovoltaic and optoelectronic device applications, respectively. However, relatively little reliable property information is available for these amorphous materials except for the well-studied end-point cases of a-Si and a-SiO2 . Our DFT calculations within the generalized gradient approximation predict that addition of H to a-Si monotonically reduces the elastic modulus (Y) by 18% and bulk modulus (B) by 16% as H incorporation increases to 15.8at.% in a-Si:H. Similarly, addition of O to a-Si monotonically reduces Y by 35% and B by 38% as x increases to 2.0 in a-SiOx . Our optical spectra for the complex dielectric function, ?(?) , exhibit intensity reduction in the E2 transition peak of Im[?(?)] and reduction in the low-frequency dielectric constant {?o=lim??0Re[?(?)]} as either H or O are added to a-Si while the a-SiOx spectra additionally resolve a vivid blueshift of both the fundamental absorption edge and E2 transition energy as O content increases. Considering the large variation in reported experimental measurements and the limited availability of previous computational results, our property predictions provide valuable insight into the mechanical and optical behavior of a-Si:H and a-SiOx materials.

Bondi, Robert J.; Lee, Sangheon; Hwang, Gyeong S.

2010-05-01

286

Silicon oxide structures measured at the surfaces of silicon and silicate glass: a reflectivity study  

Microsoft Academic Search

Using a newly developed reflectometer we have measured the reflectivity of crystalline silicon and SiOx coated float glass at the silicon K absorption edge. The reflectometer can be used without the need for ultra high vacuum. The critical angle of total reflection was determined and the reflection as function of the energy was measured below the critical angle. EXAFS analysis

G. E. van Dorssen; G. Derst; G. N. Greaves; A. D. Smith; M. Roper

1995-01-01

287

RESEARCH NOTES: Conduction in silicon nitride and silicon nitride-oxide films  

Microsoft Academic Search

The room-temperature current-voltage characterstics of vapour-deposited silicon nitride films and silicon dioxide-nitride composite structures have been investigated. It is observed that conduction is bulk-limited and conforms to the Poole-Frenkel electronic transport mechanism. However, in the composite structures, the current-limiting mechanism appears to be due to nitride layers only.

B. Swaroop; P. S. Schaffer

1970-01-01

288

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

2013-05-28

289

Crack healing behavior of hot pressed silicon nitride due to oxidation  

NASA Technical Reports Server (NTRS)

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

Choi, S. R.; Tikare, V.

1992-01-01

290

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

NASA Technical Reports Server (NTRS)

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

Call, R. L.

1976-01-01

291

Small-angle x-ray scattering study of anodically oxidized porous silicon layers  

Microsoft Academic Search

Small-angle x-ray scattering was used to investigate the microstructural change induced by electrochemical oxidation of porous silicon (PS) layers. It is shown that when the oxidation level increases, the size of the crystalline Si domains, which constitute the PS layer, decreases. This size reduction is correlated to the blue-shift observed in the photoluminescence spectra when the oxidation level is increased.

A. Naudon; P. Goudeau; A. Halimaoui; B. Lambert; G. Bomchil

1994-01-01

292

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

293

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

294

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

SciTech Connect

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

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

1993-05-01

295

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

PubMed

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

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

2013-11-01

296

Deep-level dominated current-voltage characteristics of buried implanted oxide silicon-on-insulator  

Microsoft Academic Search

Current-voltage characteristics of Au contacts formed on buried implanted oxide silicon-on-insulator (SOI) structures are discussed, which indicate that the dominant transport mechanism is space-charge-limited current (SCLC) conduction in the presence of deep-level states. The deep-level parameters, determined using a simple analysis, appear to be sensitive to anneal conditions used and subsequent processing. Silicon implanted with 1.7×1018 cm-2 oxygen ions at

K. Das; J. W. Palmour; J. B. Posthill; T. P. Humphreys; J. O'Sullivan-French; N. J. Byrd; D. Lu; J. J. Wortman; N. H. Parikh

1989-01-01

297

Silicon alleviates oxidative damage of wheat plants in pots under drought  

Microsoft Academic Search

Drought-induced changes in oxidative damage to photosynthetic pigments, proteins and lipids, some enzyme activities and photosynthesis were investigated in wheat (Triticum aestivum L.) plants grown in pots applied with or without silicon under drought stress. Three treatments with three replicates were composed of “CK” (control, 2.11mmol of sodium sulfate Kg?1soil), “DR” (drought, 2.11mmol of sodium sulfate Kg?1soil) and “DSi” (drought+silicon,

Haijun Gong; Xueyi Zhu; Kunming Chen; Suomin Wang; Chenglie Zhang

2005-01-01

298

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

Microsoft Academic Search

For pt.II, see ibid., vol.28, no.1, p.164-75 (1992). 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

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

1992-01-01

299

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 µm) 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

300

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

301

Transparent conducting oxide layers for thin film silicon solar cells  

Microsoft Academic Search

Texture etching of ZnO:1%Al layers using diluted HCl solution provides excellent TCOs with crater type surface features for the front contact of superstrate type of thin film silicon solar cells. The texture etched ZnO:Al definitely gives superior performance than Asahi SnO2:F TCO in case of nanocrystalline silicon (nc-Si) type of solar cells. The stress of the ZnO:Al film changes from

J. K. Rath; Y. Liu; M. M. de Jong; J. de Wild; J. A. Schuttauf; M. Brinza; R. E. I. Schropp

2010-01-01

302

Molecular dynamics studies of friction between bare and oxidized silicon surfaces  

NASA Astrophysics Data System (ADS)

Using molecular dynamics simulation we examine the friction between a bare silicon tip and a silicon surface under perfect vacuum conditions. The simulations utilize a Stillinger-Weber model for the Si-Si interactions. In the case of bare silicon (100) the proper surface reconstructed is verified. Silicon-silicon sliding leads to high friction and significant wear due to the strong adhesive force between tip and surface. Repeated adhesion and shearing produces a stick-slip motion. The quantity of material lost during sliding depends on the relative orientation of the dimer rows between the reconstructed surfaces of the tip and substrate. Little dependence on the temperature or the normal force is observed in this case. The frictional force does not change significantly even when an upward normal force is applied to the tip force, although the quantity of lost material depends on the magnitude of upward normal force. The geometry and elasticity dependence of the stick-slip motion has also been analyzed. We have also begun investigations of a similar geometry in which the silicon is coated with a thin oxide layer. A charge transfer potential having 3-body terms as well as pair-wise interactions is being used to model the amorphous silica interactions. These simulation results will be compared to the recent AFM experiments by Schirmeisen et al. measuring the frictional forces between an oxidized silicon tip and substrate.

Kim, Woo Kyun; Falk, Michael

2007-03-01

303

Silicon Oxide Deposition into a Hole Using a Focused Ion Beam  

NASA Astrophysics Data System (ADS)

Focused ion beam (FIB)-induced deposition of silicon oxide in terms of filling a hole is reported. It was found that a vacant space was formed when an ion beam was simply scanned through the hole area. To investigate the mechanism to form the vacancy, deposition on the sample, which has a step with a height of 0.8 ?m, was carried out by using a Si2+ and a Be2+ ion beam. An extruded deposit resembling a pent roof was observed from the step ridge. The mechanism of the pent roof growth on the steplike sample was considered and the vacancy formation in the hole can be explained by the same mechanism. For silicon oxide, the high growth rate of the extruded deposit is thought to be the key to the vacancy formation. A useful way is proposed to fill the hole with silicon oxide with almost no vacancy.

Nakamura, Hiroko; Komano, Haruki; Norimatu, Kenji; Gomei, Yoshio

1991-11-01

304

New Through-Wafer Via Interconnections with Thick Oxidized Porous Silicon Sidewall Via  

NASA Astrophysics Data System (ADS)

In this paper, we present the detailed fabrication process and high-frequency characterization of a new silicon through-wafer via interconnection and a low pass filter module flip-chip bonded to these via interconnections. An oxide liner of 18 ?m thick for the via was fabricated on a complementary metal-oxide-semiconductor (CMOS)-grade low-resistivity 5 ?\\cdotcm silicon wafer using the oxidized porous silicon (OPS) process. The through-wafer vias were filled with copper by electroplating. For a via interconnection of 240 ?m length and 70 ?m diameter, the series inductance and resistance are 0.079 nH and 0.059 ? each. A coplanar waveguide (CPW) and a RF low pass filter (LPF) module were assembled on this through-wafer via interconnection substrate.

Kim, Bun?Joong; Ha, Man?Lyun; Kwon, Young?Se

2006-08-01

305

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

PubMed Central

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

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

2010-01-01

306

Optical properties of bismuth borate glasses  

Microsoft Academic Search

Optical properties of glasses in the binary system bismuth oxide (Bi2O3)–boric oxide (B2O3) are measured for the composition range 25–65 mol% Bi2O3. Both, refractive indices and ultraviolet absorption edge, show an expressed dependence on composition. A generalized Sellmeier formula is derived to describe the refractive indices for the whole composition range and a wide wavelength range.

Isabella-Ioana Oprea; Hartmut Hesse; Klaus Betzler

2004-01-01

307

Raman scattering and infrared absorption of silicon nanocrystals in silicon oxide matrix  

Microsoft Academic Search

Structural dependence on annealing of a-SiOx:H was studied by using infrared absorption and Raman scattering. The appearance of Raman peaks in the range of 513 - 519 cm-1 after 1170 degree(s)C annealing was interpreted as the formation nanocrystalline silicon with the sizes from 3 - 10 nm. The Raman spectra also show the existence of amorphous-like silicon phase, which is

Zhixun Ma; Xianbo Liao; Weimin Zheng; Jian Yu; Junhao Chu

2000-01-01

308

Combustion of Binary and Ternary Silicon\\/Oxidant Pyrotechnic Systems, Part I: Binary Systems with Fe203 and Sn02 as Oxidants  

Microsoft Academic Search

Abstract– The results of a detailed study of the combustion of several binary silicon\\/oxidant pyrotechnic systems are reported in this and three immediately following papers. The overall aim of the study was to investigate the role of different oxidants in binary combination with silicon as the common fuel.Temperature profiles of the burning pyrotechnic compositions have been recorded. simultaneously with measurements

R. Anil Rugunanan; Michael E. Brown

1993-01-01

309

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

NASA Technical Reports Server (NTRS)

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

Connor, D.; Holmryd, S.

1969-01-01

310

Properties of Thermal Gadolinium Oxide Films on Silicon  

NASA Astrophysics Data System (ADS)

The formation and electrical characteristics of thermal gadolinium (Gd) oxide films were investigated. A good uniform interface formed by proper treatment was observed by transmission electron microscopy (TEM) examination. The dielectric constant of the thermal Gd oxide films was approximately 10 from capacitance-voltage measurements. The X-ray diffraction (XRD) pattern of the thermal Gd oxide (Gd2O3) films showed that they had a cubic structure. The Gd oxides that were oxidized at higher temperatures exhibited smaller grain boundaries than those oxidized at lower temperatures. The grain boundary size of the Gd oxides significantly affects the leakage property. A good Gd oxide quality can be obtained when the thermal oxidation temperature is above 900°C.

Ko, Hong-Hsi; Chang, Liann-Be; Jeng, Ming-Jer; Kuei, Ping-Yu; Horng, Kuo-Yang

2005-05-01

311

Fabrication of OSOS cells by neutral ion beam sputtering. [Oxide Semiconductor On Silicon solar cells  

NASA Technical Reports Server (NTRS)

Oxide semiconductor on silicon (OSOS) solar cells have been fabricated from various indium tin oxide (In2O3)x(SnO2)1-x compositions sputtered onto p-type single crystal silicon substrates with a neutralized argon ion beam. High temperature processing or annealing was not required. The highest efficiency was achieved with x = 0.91 and was 12 percent. The cells are environmentally rugged, chemically stable, and show promise for still higher efficiencies. Moreover, the ion beam sputtering fabrication technique is amenable to low cost, continuous processing.

Burk, D. E.; Dubow, J. B.; Sites, J. R.

1976-01-01

312

Combustion of Binary and Ternary Silicon\\/Oxidant Pyrotechnic Systems, Part III: Ternary Systems  

Microsoft Academic Search

Abstract–studies of tbe combustion of several binary silicon\\/oxidant pyrotechnic systems (Si\\/Fe2o3, Si\\/SnO2, Si\\/Sb2O3 and Si\\/KNO3) have been extended to examine the behaviour of ternary systems with silicon as fuel and binary combinations of the above oxidants. The effects of substituting ferrosilicon, FeSi7, or calcium silicide, CaSi2, for some or all of the Si in the above systems have also been

R. Anil Rugunanan; Michael E. Brown

1993-01-01

313

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 400°C. 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

314

Selective electrochemical oxidation of heteroatom compounds having both silicon and tin on the same carbon as electroauxiliaries  

Microsoft Academic Search

The selective electrochemical oxidation of heteroatom compounds having two different electroauxiliaries, i.e. silicon and tin, on the same ?-carbon was examined. The oxidation potentials of such compounds were found to be similar to those of the corresponding compounds having only tin, indicating the predominant role of tin over that of silicon. The HOMO levels obtained by the molecular orbital calculations

Jun-ichi Yoshida; Mitsuru Watanabe; Hideaki Toshioka; Masayuki Imagawa; Seiji Suga

2001-01-01

315

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)] [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

316

Laser Fired Aluminum Emitter for High Efficiency Silicon Photovoltaics Using Hydrogenated Amorphous Silicon and Silicon Oxide Dielectric Passivation  

NASA Astrophysics Data System (ADS)

This thesis proposes and demonstrates a hydrogenated amorphous silicon passivated, inverted photovoltaic device on n-type silicon, utilizing a Laser Fired Emitter on a rear i-a- Si:H/SiO x dielectric stack. This novel low-temperature-fabricated device architecture constitutes the first demonstration of an LFE on a dielectric passivation stack. The optimization of the device is explored through Sentaurus computational modeling, predicting a potential efficiency of >20%. Proof of concept devices are fabricated using the DC Saddle Field PECVD system for the deposition of hydrogenated amorphous silicon passivation layers. Laser parameters are explored highlighting pulse energy density as a key performance determining factor. Annealing of devices in nitrogen atmosphere shows performance improvements albeit that the maximum annealing temperature is limited by the thermal stability of the passivation. A proof of concept device efficiency of 11.1% is realized forming the basis for further device optimization.

Fischer, Anton

317

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

NASA Astrophysics Data System (ADS)

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

Haney, Sarah Kay

318

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

NASA Technical Reports Server (NTRS)

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

Opila, Elizabeth J.; Nguyen, QuynhGiao N.

1998-01-01

319

Surface and Interface Structures of Crystalline Oxides on Silicon (COS)  

NASA Astrophysics Data System (ADS)

The structure of the Sr-covered Si(001) surface (the precursor to COS heteroepitaxy) is a matter of on-going scientific debate with experiment and theory casting opposing views. Real space Z-contrast imaging shows that half of the silicon atoms on the (001) surface are absent, and this has presented us with the intriguing question -- ``Where does the silicon go?''. A metallic surface termination of silicon was required in the layer-sequenced heteroepitaxy of COS. What has been common to all experimental realizations of the layer-sequenced COS structure, is the presence of hydrogen evolving from the metal sources during the film growth. We report here that this hydrogen has inadvertently played a pivotal role in defining the silicon termination and thus the evolution of the interface structure for COS. We will describe the thermodynamic basis for this hydrogen effect along with experimental and theoretical characterization of the structural details. Research sponsored jointly by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy at Oak Ridge National Laboratory under contract DE-AC05-00OR22725 with UT-Battelle, LLC and at the University of Tennessee under contract DE-FG02-01ER45937. Calculations have been performed on CCS supercomputers at Oak Ridge National Laboratory.

Walker, Fred; Buongiorno-Nardelli, Marco; McKee, Rodney

2006-03-01

320

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

321

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

NASA Astrophysics Data System (ADS)

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.

Zhang, Qiaohong; Chen, Chen; Wang, Min; Cai, Jiaying; Xu, Jie; Xia, Chungu

2011-11-01

322

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

323

Enhanced photoresponse of a metal-oxide-semiconductor photodetector with silicon nanocrystals embedded in the oxide layer  

NASA Astrophysics Data System (ADS)

The authors report a two-terminal metal-oxide-semiconductor photodetector for which light is absorbed in a capping layer of silicon nanocrystals embedded in a mesoporous silica matrix on p-type silicon substrates. Operated at reverse bias, enhanced photoresponse from 300 to 700 nm was observed. The highest optoelectronic conversion efficiency is as high as 200%. The enhancements were explained by a transistorlike mechanism, in which the inversion layer acts as the emitter and trapped positive charges in the mesoporous dielectric layer assist carrier injection from the inversion layer to the contact, such that the primary photocurrent could be amplified.

Shieh, Jia-Min; Lai, Yi-Fan; Ni, Wei-Xin; Kuo, Hao-Chung; Fang, Chih-Yao; Huang, Jung Y.; Pan, Ci-Ling

2007-01-01

324

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

PubMed

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

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

2012-01-01

325

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; Klinkmüller, Matthias; Fedosenko, Oliana; Machulik, Stephan; Aleksandrova, Anna; Monastyrskyi, Gregorii; Flores, Yuri; Masselink, W Ted

2012-10-01

326

Anodic oxidation of polycrystalline 3C-silicon carbide thin films during MEMS operation  

NASA Astrophysics Data System (ADS)

In this paper, we provide the first report of corrosion occurring at the anode of polycrystalline 3C-silicon carbide MEMS electrodes under high relative humidity and applied voltage. This unusual phenomenon is determined to be electrochemical in nature. Electrode pair and canary wire corrosion behavior are investigated to yield a detailed evaluation of the stability and oxidation rate during corrosion. The effects of film stress on anodic oxidation are discussed, and suggestions to prevent damage due to corrosion are presented.

Liu, F; Roper, C S; Laboriante, I; Bush, B; Chu, J R; Carraro, C; Maboudian, R

2009-03-01

327

MOS-junction-based nanostructures by thermal oxidation of silicon wires for hydrogen detection  

Microsoft Academic Search

Heavily p-doped monocrystalline silicon wires have been fabricated by employing isotropic Si wet etch and thermal oxidation to achieve a nanometric cross section-a gate-oxide growth and a final palladium evaporation made up the MOS junction able to detect hydrogen concentration in air. Several types of wire dimensions have been designed and fabricated: length ranges from 5 to 70 ?m; the

Arianna Tibuzzi; Benno Margesin; Massimiliano Decarli; C. Di Natale; M. Zen; A. D'Amico; G. Soncini

2004-01-01

328

Zinc oxide nanowire arrays for silicon core/shell solar cells.  

PubMed

The optics of core / shell nanowire solar cells was investigated. The optical wave propagation was studied by finite difference time domain simulations using realistic interface morphologies. The interface morphologies were determined by a 3D surface coverage algorithm, which provides a realistic film formation of amorphous silicon films on zinc oxide nanowire arrays. The influence of the nanowire dimensions on the interface morphology and light trapping was investigated and optimal dimensions of the zinc oxide nanowire were derived. PMID:24922370

Tamang, Asman; Pathirane, Minoli; Parsons, Rion; Schwarz, Miriam M; Iheanacho, Bright; Jovanov, Vladislav; Wagner, Veit; Wong, William S; Knipp, Dietmar

2014-05-01

329

Silicon metal-semiconductor–metal photodetector with zinc oxide transparent conducting electrodes  

Microsoft Academic Search

Transparent conducting oxides thin layers, due to their optical and electrical properties, can be used as transparent electrodes in various optoelectronic devices. We present a metal-semiconductor–metal photodiode (MSM-PD) on silicon as optically active layer with zinc oxide (ZnO) thin layer as interdigitated Schottky transparent electrodes. The advantage of using a ZnO thin layer as Schottky electrodes consists in the improvement

E. Budianu; M. Purica; F. Iacomi; C. Baban; P. Prepelita; E. Manea

2008-01-01

330

Early Stage of Silicon Oxidation Studied by in situ X-Ray Photoelectron Spectroscopy  

Microsoft Academic Search

In this study, a clean silicon surface is oxidized in a UHV chamber and the surface suboxide compositions are analyzed using in situ X-ray photoelectron spectroscopy. It is found that the predominant suboxides are Si2O3 and SiO irrespective of crystallographic orientations in the early stages of oxidation. This is interpreted in terms of a significant number of atomic steps existing

Masaru Takakura; Tsuyoshi Ogura; Tsukasa Hayashi; Masataka Hirose

1988-01-01

331

Interface structure between silicon and its oxide by first-principles molecular dynamics  

Microsoft Academic Search

The requirement for increasingly thin (<50Å) insulating oxide layers in silicon-based electronic devices highlights the importance of characterizing the Si-SiO2 interface structure at the atomic scale. Such a characterization relies to a large extent on an understanding of the atomic-scale mechanisms that govern the oxidation process. The widely used Deal-Grove model invokes a two-step process in which oxygen first diffuses

Alfredo Pasquarello; Mark S. Hybertsen; Roberto Car

1998-01-01

332

Fabrication and characterisation of thin low-temperature MBE-compatible silicon oxides of different stoichiometry  

Microsoft Academic Search

We developed and tested three MBE-compatible processes for the deposition of high-quality low-temperature silicon oxides and oxynitrides in the ultra high vacuum at substrate temperatures between room temperature and 500°C: gas enhanced evaporation (GEE), plasma enhanced evaporation (PEE) and plasma enhanced oxidation (PEO). The deposited layers were thoroughly investigated and compared with respect to their electrical, optical and stoichiometrical properties

A. Strass; P. Bieringer; W. Hansch; V. Fuenzalida; A. Alvarez; J. Luna; I. Martil; F. L. Martinez; I. Eisele

1999-01-01

333

A Model for the Oxidation of Carbon Silicon Carbide Composite Structures  

NASA Technical Reports Server (NTRS)

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 porous solid. The result of the theoretical formulation is a set of two coupled nonlinear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The nonlinear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual method, allowing for the solution of the differential equations numerically. The numerical method is demonstrated by utilizing the method to model the carbon oxidation and weight loss behavior of C/SiC specimens during thermogravimetric experiments. The numerical method is used to study the physics of carbon oxidation in carbon silicon carbide composites.

Sullivan, Roy M.

2004-01-01

334

Magnetometer uses bismuth-selenide  

NASA Technical Reports Server (NTRS)

Characteristics of bismuth-selenide magnetometer are described. Advantages of bismuth-selenide magnetometer over standard magnetometers are stressed. Thermal stability of bismuth-selenide magnetometer is analyzed. Linearity of output versus magnetic field over wide range of temperatures is reported.

Woollman, J. A.; Spain, I. L.; Beale, H.

1972-01-01

335

Metal Oxide Silicon /MOS/ transistors protected from destructive damage by wire  

NASA Technical Reports Server (NTRS)

Loop of flexible, small diameter, nickel wire protects metal oxide silicon /MOS/ transistors from a damaging electrostatic potential. The wire is attached to a music-wire spring, slipped over the MOS transistor case, and released so the spring tensions the wire loop around all the transistor leads, shorting them together. This allows handling without danger of damage.

Deboo, G. J.; Devine, E. J.

1966-01-01

336

Silicon-on-insulator technology for high temperature metal oxide semiconductor devices and circuits  

Microsoft Academic Search

The high temperature characteristics of devices and circuits realized in complementary metal oxide semiconductor (CMOS) technology on silicon-on-insulator (SOI) substrates are compared with other materials, and it is demonstrated that CMOS on SOI is presently the most suitable process for the realization of electronic circuits operating at up to more than 300 °C.

Denis Flandre

1995-01-01

337

Improved reaction sintered silicon nitride. [protective coatings to improve oxidation resistance  

NASA Technical Reports Server (NTRS)

Processing treatments were applied to as-nitrided reaction sintered silicon nitride (RSSN) with the purposes of improving strength after processing to above 350 MN/m2 and improving strength after oxidation exposure. The experimental approaches are divided into three broad classifications: sintering of surface-applied powders; impregnation of solution followed by further thermal processing; and infiltration of molten silicon and subsequent carburization or nitridation of the silicon. The impregnation of RSSN with solutions of aluminum nitrate and zirconyl chloride, followed by heating at 1400-1500 C in a nitrogen atmosphere containing silicon monoxide, improved RSSN strength and oxidation resistance. The room temperature bend strength of RSSN was increased nearly fifty percent above the untreated strength with mean absolute strengths up to 420 MN/m2. Strengths of treated samples that were measured after a 12 hour oxidation exposure in air were up to 90 percent of the original as-nitrided strength, as compared to retained strengths in the range of 35 to 60 percent for untreated RSSN after the same oxidation exposure.

Baumgartner, H. R.

1978-01-01

338

Thermally excited silicon oxide beam and bridge resonators in CMOS technology  

Microsoft Academic Search

The design, fabrication, and characterization of thermally excited silicon oxide beam and bridge resonators by a modern industrial CMOS process combined with one additional maskless etching step is reported. The resonant frequencies, vibration amplitudes, and mode shapes of the devices are measured using a laser heterodyne interferometer. The acoustic transmitting and receiving sensitivities of the resonant structures in air are

Oliver Brand; Henry Baltes; Urs Baldenweg

1993-01-01

339

A CMOS compatible thermally excited silicon oxide beam resonator with aluminum mirror  

Microsoft Academic Search

The authors designed, manufactured, and characterized a thermally excited silicon oxide beam resonator based on CMOS technology with subsequent micromachining. Besides optical measurements of the resonance frequencies and vibration amplitudes, the acoustic transmission efficiency of the device in air was investigated. At a fundamental resonance of 10.35 kHz, a vibration amplitude of 2 ?m at the tip of the beam

D. Moser; O. Brand; H. Baltes

1991-01-01

340

Ordered networks of rat hippocampal neurons attached to silicon oxide surfaces  

Microsoft Academic Search

The control of neuronal cell position and outgrowth is of fundamental interest in the development of applications ranging from cellular biosensors to tissue engineering. We have produced rectangular networks of functional rat hippocampal neurons on silicon oxide surfaces. Attachment and network formation of neurons was guided by a geometrical grid pattern of the adhesion peptide PA22-2 which matches in sequence

M. Scholl; C. Sprossler; M. Denyer; M. Krause; K. Nakajima; A. Maelicke; W. Knoll; A. Offenhausser

2000-01-01

341

Topography of obliquely evaporated silicon oxide films and its effect on liquid-crystal orientation  

Microsoft Academic Search

The topography of silicon oxide films deposited at an angle of incidence of either 60° or 83° has been investigated using transmission electron microscopy. Columnar-growth structure arrayed in rowlike order has been detected for films deposited at both angles of incidence. The columns lie in the plane of incidence in both cases. The column angle of inclination from the normal

L. A. Goodman; J. T. McGinn; CHARLES H. ANDERSON; FRANK DIGERONIMO

1977-01-01

342

Electroluminescence of heavily doped p-type porous silicon under electrochemical oxidation in galvanostatic regime  

Microsoft Academic Search

Visible light emission is obtained during anodic oxidation of heavily doped p-type (P{sup +}) porous silicon layers. Similar characteristics are observed for the electroluminescence (EL) on lightly doped substrates (P⁻). This indicates that the coarser structure of the heavily doped samples also presents a thin structure, with crystallites of quantum sizes responsible for the emission. For the first time the

S. Billat

1996-01-01

343

Mechanisms of visible-light emission from electro-oxidized porous silicon  

Microsoft Academic Search

High-porosity porous silicon, after electrochemical oxidation, is a stable and highly reproducible luminescent material with a luminescence quantum efficiency as high as 3% at room temperature. Luminescence decay rates as long as several hundreds of microseconds show that radiative and nonradiative processes both have low efficiencies even at room temperature. This shows that confinement of carriers inside nanometer-sized crystallites does

J. C. Vial; A. Bsiesy; F. Gaspard; R. Hérino; M. Ligeon; F. Muller; R. Romestain; R. M. Macfarlane

1992-01-01

344

Electroluminescence of heavily doped p-type porous silicon under electrochemical oxidation in the potentiostatic regime  

Microsoft Academic Search

Visible light emission is obtained during the anodic oxidation of heavily doped p-type porous silicon layers, with similar characteristics to the electroluminescence observed on lightly doped substrates. This indicates that the coarser structure of the heavily doped layers also presents a thinner structure, with crystallites of quantum sizes responsible for the emission. In this paper, the electroluminescence is studied in

S. Billat; F. Gaspard; R. Hérino; M. Ligeon; F. Muller; F. Romestain; J. C. Vial

1995-01-01

345

Gadolinium Oxide / Silicon Thin Film Heterojunction Solid-State Neutron Detector.  

National Technical Information Service (NTIS)

The internal conversion electron emission from the de-excitation of the Gd-158m nucleus was explored as a means for neutron detection. Thin film gadolinium oxide (Gd2O3) and p-type silicon heterojunction diodes were produced using a supercritical water de...

C. M. Young

2010-01-01

346

Ion implanted boron emitter N-silicon solar cells with wet oxide passivation  

Microsoft Academic Search

An ion implanted boron emitter silicon solar cell is demonstrated. By using appropriate annealing condition, the implanted dopants and damage introduced by the implantation can be activated and repaired, respectively. Both the rapid thermal annealing (RTA) and furnace annealing were investigated within this work. For the surface passivation and the antireflection coating, the wet oxide (SiO2) was grown during the

W. S. Ho; Y.-H. Huang; W.-W. Hsu; Y.-Y. Chen; C. W. Liu

2011-01-01

347

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

348

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, 1000°C, <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

349

Properties of Thermal Gadolinium Oxide Films on Silicon  

Microsoft Academic Search

The formation and electrical characteristics of thermal gadolinium (Gd) oxide films were investigated. A good uniform interface formed by proper treatment was observed by transmission electron microscopy (TEM) examination. The dielectric constant of the thermal Gd oxide films was approximately 10 from capacitance-voltage measurements. The X-ray diffraction (XRD) pattern of the thermal Gd oxide (Gd2O3) films showed that they had

Hong-Hsi Ko; Liann-Be Chang; Ming-Jer Jeng; Ping-Yu Kuei; Kuo-Yang Horng

2005-01-01

350

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

351

Electroluminescence with high and stable quantum efficiency and low threshold voltage from anodically oxidized thin porous silicon diode  

Microsoft Academic Search

Highly efficient electroluminescence (EL) is obtained at low operating voltage (<5 V) from n+-type silicon-electrochemically oxidized thin porous silicon-indium-tin-oxide junctions. Continuous wave external quantum efficiency greater than 1% and power efficiency of 0.37% have been achieved. Considerable reduction of leakage current accounts for the enhancement of EL efficiency upon oxidation. The EL time response (~30 mus) is slower than the

Bernard Gelloz; Nobuyoshi Koshida

2000-01-01

352

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

PubMed Central

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

2014-01-01

353

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

PubMed

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

Miyake, Shojiro; Yamazaki, Shohei

2014-01-01

354

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

355

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 1000°C.

Earl A. Gulbransen; Sven A. Jansson

1972-01-01

356

Protein-repellent silicon nitride surfaces: UV-induced formation of oligoethylene oxide monolayers.  

PubMed

The grafting of polymers and oligomers of ethylene oxide onto surfaces is widely used to prevent nonspecific adsorption of biological material on sensors and membrane surfaces. In this report, we show for the first time the robust covalent attachment of short oligoethylene oxide-terminated alkenes (CH(3)O(CH(2)CH(2)O)(3)(CH(2))(11)-(CH?CH(2)) [EO(3)] and CH(3)O(CH(2)CH(2)O)(6)(CH(2))(11)-(CH?CH(2)) [EO(6)]) from the reaction of alkenes onto silicon-rich silicon nitride surfaces at room temperature using UV light. Reflectometry is used to monitor in situ the nonspecific adsorption of bovine serum albumin (BSA) and fibrinogen (FIB) onto oligoethylene oxide coated silicon-rich silicon nitride surfaces (EO(n)-Si(x)N(4), x > 3) in comparison with plasma-oxidized silicon-rich silicon nitride surfaces (SiO(y)-Si(x)N(4)) and hexadecane-coated Si(x)N(4) surfaces (C(16)-Si(x)N(4)). A significant reduction in protein adsorption on EO(n)-Si(x)N(4) surfaces was achieved, adsorption onto EO(3)-Si(x)N(4) and EO(6)-Si(x)N(4) were 0.22 mg m(-2) and 0.08 mg m(-2), respectively. The performance of the obtained EO(3) and EO(6) layers is comparable to those of similar, highly protein-repellent monolayers formed on gold and silver surfaces. EO(6)-Si(x)N(4) surfaces prevented significantly the adsorption of BSA (0.08 mg m(-2)). Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray reflectivity and static water contact angle measurements were employed to characterize the modified surfaces. In addition, the stability of EO(6)-Si(x)N(4) surfaces in phosphate-buffered saline solution (PBS) and alkaline condition (pH 10) was studied. Prolonged exposure of the surfaces to PBS solution for 1 week or alkaline condition for 2 h resulted in only minor degradation of the ethylene oxide moieties and no oxidation of the Si(x)N(4) substrates was observed. Highly stable antifouling coatings on Si(x)N(4) surfaces significantly broaden the application potential of silicon nitride-coated microdevices, and in particular of microfabricated filtration membranes. PMID:21309535

Rosso, Michel; Nguyen, Ai T; de Jong, Ed; Baggerman, Jacob; Paulusse, Jos M J; Giesbers, Marcel; Fokkink, Remko G; Norde, Willem; Schroën, Karin; van Rijn, Cees J M; Zuilhof, Han

2011-03-01

357

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

NASA Technical Reports Server (NTRS)

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

Opila, Elizabeth J.

1994-01-01

358

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.

García, H.; Dueñas, S.; Castán, H.; Gómez, A.; Bailón, L.; Toledano-Luque, M.; Del Prado, A.; Mártil, I.; González-Díaz, G.

2008-11-01

359

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 700ºC 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 700ºC to 800ºC. Oxidation resistances of alloys with Si only additions were outstanding, particularly at 800ºC (i.e., these alloys possessed weight gains 4 times less than a standard type-304 alloy). In addition, Si alloys pre-oxidized at 800ºC, showed a zero weight gain in subsequent testing for 1000 hours at 700ºC. Similar improvements were observed for Si only alloy after H2S exposure at 700ºC 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

360

Multifunctional silicon-based light emitting device in standard complementary metal—oxide—semiconductor technology  

NASA Astrophysics Data System (ADS)

A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 ?m complementary metal—oxide—semiconductor 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 V—12 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

361

Fundamental steps towards interface amorphization during silicon oxidation: Density functional theory calculations  

NASA Astrophysics Data System (ADS)

Density functional theory calculations reveal a two-step scenario for silicon oxidation nucleation. We detail a quasibarrierless semihexagonal oxide nucleus, involving an unexpected adjacent dimer oxygen bridging bond. It is formed upon O2 chemisorption at 0.5 monolayer on Si(100)-(2×1) . This structure arises from the difficulty to systematically insert oxygen atoms into first neighbor Si-Si bonds. While silanone structures, characterized by a Si=O strand, effectively accommodate oxygen at lower coverages, the stabilization of this hexagonal-like pattern on a cubic substrate at low temperatures and at higher coverages demonstrates the ability of oxygen atoms to deeply modify the arrangement of silicon atoms on the surface and to impose a specific structure. It is believed to offer a key natural pathway toward the formation of an abrupt crystalline semiconductor/amorphous oxide transition.

Hemeryck, A.; Estève, A.; Richard, N.; Djafari Rouhani, M.; Chabal, Y. J.

2009-01-01

362

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

363

Graphene Oxide-Immobilized NH2-Terminated Silicon Nanoparticles by Cross-Linked Interactions for Highly Stable Silicon Negative Electrodes.  

PubMed

There is a great interest in the utilization of silicon-based anodes for lithium-ion batteries. However, its poor cycling stability, which is caused by a dramatic volume change during lithium-ion intercalation, and intrinsic low electric conductivity hamper its industrial applications. A facile strategy is reported here to fabricate graphene oxide-immobilized NH2-terminated silicon nanoparticles (NPs) negative electrode (Si@NH2/GO) directed by hydrogen bonding and cross-linked interactions to enhance the capacity retention of the anode. The NH2-modified Si NPs first form strong hydrogen bonds and covalent bonds with GO. The Si@NH2/GO composite further forms hydrogen bonds and covalent bonds with sodium alginate, which acts as a binder, to yield a stable composite negative electrode. These two chemical cross-linked/hydrogen bonding interactions-one between NH2-modified Si NPs and GO, and another between the GO and sodium alginate-along with highly mechanically flexible graphene oxide, produced a robust network in the negative electrode system to stabilize the electrode during discharge and charge cycles. The as-prepared Si@NH2/GO electrode exhibits an outstanding capacity retention capability and good rate performance, delivering a reversible capacity of 1000 mAh g(-1) after 400 cycles at a current of 420 mA g(-1) with almost 100% capacity retention. The results indicated the importance of system-level strategy for fabricating stable electrodes with improved electrochemical performance. PMID:24922522

Sun, Cheng; Deng, Yuanfu; Wan, Lina; Qin, Xusong; Chen, Guohua

2014-07-23

364

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

365

Crack healing in silicon nitride due to oxidation  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

366

Laser spectroscopy of nanocrystals of aluminum and silicon oxides  

Microsoft Academic Search

The specific features of the spectra of secondary radiation (photoluminescence and Raman scattering) in nanocrystalline samples\\u000a of aluminum oxide and fused silica are reported. The photoluminescence (PL) spectrum of nanocrystalline aluminum oxide was\\u000a found to be strongly modified with the wavelength of exciting radiation. Spectra of secondary radiation were excited using\\u000a a xenon lamp, a pulsed nitrogen laser (with a

V. S. Gorelik; A. E. Kozhevin; S. N. Mikov; P. P. Sverbil’; M. M. Stepanov

2007-01-01

367

Anisotropy in the anodic oxidation of silicon in KOH solution  

Microsoft Academic Search

The electrochemical oxidation and passivation of Si(100) and Si(111) electrodes in KOH solution was studied\\u000aby potentiodynamic and potential-step measurements. Striking differences were observed between the surfaces.\\u000aA comparison of the results for n- and p-type electrodes led us to conclude that electrochemical oxidation of\\u000asilicon in alkaline solution must be triggered by a chemical reaction. The strong influence of

Harold G. G. Philipsen; John J. Kelly

2005-01-01

368

Observation of interfacial atomic steps during silicon oxidation  

Microsoft Academic Search

The Si\\/SiO2 interface has excellent electrical properties which are employed in field-effect devices and surface passivation. As device dimensions shrink, the need for high-quality oxides grown at increasingly lower thicknesses and temperatures has demanded ever more perfect, extremely flat Si\\/SiO2 interfaces. Here, TEM is used to image exposed and buried monatomic interfacial steps at Si\\/SiO2 interface during oxidation. The results

J. M. Gibson; M. Y. Lanzerotti

1989-01-01

369

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

370

Oxidation-enhanced diffusion of boron in very low-energy N2+-implanted silicon  

NASA Astrophysics Data System (ADS)

In this article we study the interstitial injection during oxidation of very low-energy nitrogen-implanted silicon. Buried boron ? layers are used to monitor the interstitial supersaturation during the oxidation of nitrogen-implanted silicon. No difference in boron diffusivity enhancement was observed compared to dry oxidation of nonimplanted samples. This result is different from our experience from N2O oxynitridation study, during which a boron diffusivity enhancement of the order of 20% was observed, revealing the influence of interfacial nitrogen on interstitial kinetics. A possible explanation may be that implanted nitrogen acts as an excess interstitial sink in order to diffuse towards the surface via a non-Fickian mechanism. This work completes a wide study of oxidation of very low-energy nitrogen-implanted silicon related phenomena we performed within the last two years [D. Skarlatos, C. Tsamis, and D. Tsoukalas, J. Appl. Phys. 93, 1832 (2003); D. Skarlatos, E. Kapetanakis, P. Normand, C. Tsamis, M. Perego, S. Ferrari, M. Fanciulli, and D. Tsoukalas, J. Appl. Phys. 96, 300 (2004)].

Skarlatos, D.; Tsamis, C.; Perego, M.; Fanciulli, M.

2005-06-01

371

Abnormal room-temperature oxidation of silicon in the presence of copper  

NASA Astrophysics Data System (ADS)

The room-temperature reaction between copper (Cu) and silicon (Si) was investigated. The areas of an Si substrate covered with very thin or island-like Cu oxidized formed thick (>100 nm) oxide (SiO2). The areas covered with thick and nonisland-like Cu film did not. These unoxidized areas transformed into SiO2 when the side surfaces of the sample were exposed to air after sectioning for transmission electron microscope observation. The supply of oxygen was found to control this oxidation process. The presence of a Cu silicide, such as Cu3Si, was found to not necessarily be needed for oxidation. The oxidation rate estimated from observation was about 150 nm/month. Copper atoms were detected at the SiO2/Si interface and identified not as silicides but as body-center-cubic-structured Cu several atom layers thick. copyright 2002 American Vacuum Society.

Hinode, Kenji; Takeda, Ken'ichi; Kondo, Seiichi

2002-09-01

372

Synthesis of zinc oxide varistors with a breakdown voltage of three volts using an intergranular glass phase in the bismuth-boron-oxide system  

Microsoft Academic Search

Zinc oxide (ZnO) crystals joined by using an intergranular glass phase were investigated in order to develop surge filters for low-voltage applications and to clarify the current transport mechanism through the junction. The junctions having a ZnO\\/glass\\/ZnO sandwich structure were synthesized by using an interfacial glass phase of the Bi-B-O system. A highly nonlinear current-voltage curve was obtained for the

Naoki Ohashi; Ken Kataoka; Takeshi Ohgaki; Takahira Miyagi; Hajime Haneda; Kenji Morinaga

2003-01-01

373

Controlling the formation of luminescent Si nanocrystals in plasma-enhanced chemical vapor deposited silicon-rich silicon oxide through ion irradiation  

Microsoft Academic Search

The effect of ion irradiation on the formation of luminescent Si nanocrystals from silicon-rich silicon oxide (SRSO) films deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition (PECVD) whose Si content ranged from 33 to 50 at. % is investigated. As-deposited SRSO films contained a high density of irregular-shaped Si nanocrystals. Irradiating these films with 380 keV Si at room

T. G. Kim; C. N. Whang; Yohan Sun; Se-Young Seo; Jung H. Shin; J. H. Song

2002-01-01

374

Application of total reflection X-ray fluorescence in angle scan mode to establish the location of arsenic contamination in silicon and silicon oxide, respectively  

Microsoft Academic Search

Experiments have been carried out using total reflection X-ray fluorescence (TXRF) to determine the location of arsenic cross-contamination on or in silicon and silicon oxide, respectively, caused during argon-implantation. TXRF has been applied at varying angles of incidence — the so-called angle scan mode. By comparing the angle scan curves of implanted samples with those of a wafer, spin-coated with

Ingrid Rink; Harry Thewissen

1999-01-01

375

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

NASA Technical Reports Server (NTRS)

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

Zheng, Y.; Witt, A. F.

1999-01-01

376

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 H 2SO 4/HNO 3 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

377

Addition of silicon improves oxidation resistance of nickel based superalloys  

NASA Technical Reports Server (NTRS)

Specific weight changes of nickel-base superalloy B-1900 and B-1900 + 1% Si specimens were tested at 1273 K. B-1900 was losing weight at an increasing rate due to spalling of oxide scale while B-1900 + 1% Si was still gaining weight at low, nearly constant rate. Similar comparison in weight change was observed for specimens tested at 1373 K.

Lowell, C. E.; Miner, R. V., Jr.

1974-01-01

378

Bismuth film electrodes for heavy metals determination  

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

379

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

380

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. 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

381

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2013 CFR

... (a) Identity. The color additive bismuth citrate is the synthetically prepared crystalline salt of bismuth and citric acid, consisting principally of BiC6 H5 O7 . (b) Specifications. The color additive bismuth citrate...

2013-04-01

382

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

383

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

384

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

385

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

386

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

387

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

388

Effect of Alcohol-Assisted Annealing on the Quality of Silicon Oxide Thin Film  

NASA Astrophysics Data System (ADS)

Silicon oxide thin films have been formed by use of the reaction between spin-coated silicone oil and ozone gas at atmospheric pressure and low temperature (250°C). Films formed at this temperature contained Si-OH bonds, owing to inadequate dehydration. To remove the Si-OH bonds at low temperature, the sample was dipped in ethanol at room temperature for 15 min then annealed on a hot plate at 250°C in methanol gas for 30 min. This treatment effectively dissociated the Si-OH bonds. It is believed the Si-OH bonds are replaced by Si-OCH3 bonds during the alcohol-assisted annealing. The leakage current of the metal-oxide-semiconductor after alcohol-assisted annealing was improved and the hysteresis width was reduced. This indicated that the number of trap sites owing to Si-OH bonds was reduced.

Ito, Takuya; Ota, Yasuyuki; Shiomori, Koichiro; Nishioka, Kensuke

2014-07-01

389

Aminosilane functionalizations of mesoporous oxidized silicon for oligonucleotide synthesis and detection.  

PubMed

Direct solid phase synthesis of peptides and oligonucleotides (ONs) requires high chemical stability of the support material. In this work, we have investigated the passivation ability of porous oxidized silicon multilayered structures by two aminosilane compounds, 3-aminopropyltriethoxysilane and 3-aminopropyldimethylethoxysilane (APDMES), for optical label-free ON biosensor fabrication. We have also studied by spectroscopic reflectometry the hybridization between a 13 bases ON, directly grown on the aminosilane modified porous oxidized silicon by in situ synthesis, and its complementary sequence. Even if the results show that both devices are stable to the chemicals (carbonate/methanol) used, the porous silica structure passivated by APDMES reveals higher functionalization degree due to less steric hindrance of pores. PMID:23536541

De Stefano, Luca; Oliviero, Giorgia; Amato, Jussara; Borbone, Nicola; Piccialli, Gennaro; Mayol, Luciano; Rendina, Ivo; Terracciano, Monica; Rea, Ilaria

2013-06-01

390

Aminosilane functionalizations of mesoporous oxidized silicon for oligonucleotide synthesis and detection  

PubMed Central

Direct solid phase synthesis of peptides and oligonucleotides (ONs) requires high chemical stability of the support material. In this work, we have investigated the passivation ability of porous oxidized silicon multilayered structures by two aminosilane compounds, 3-aminopropyltriethoxysilane and 3-aminopropyldimethylethoxysilane (APDMES), for optical label-free ON biosensor fabrication. We have also studied by spectroscopic reflectometry the hybridization between a 13 bases ON, directly grown on the aminosilane modified porous oxidized silicon by in situ synthesis, and its complementary sequence. Even if the results show that both devices are stable to the chemicals (carbonate/methanol) used, the porous silica structure passivated by APDMES reveals higher functionalization degree due to less steric hindrance of pores.

De Stefano, Luca; Oliviero, Giorgia; Amato, Jussara; Borbone, Nicola; Piccialli, Gennaro; Mayol, Luciano; Rendina, Ivo; Terracciano, Monica; Rea, Ilaria

2013-01-01

391

Effect of Alcohol-Assisted Annealing on the Quality of Silicon Oxide Thin Film  

NASA Astrophysics Data System (ADS)

Silicon oxide thin films have been formed by use of the reaction between spin-coated silicone oil and ozone gas at atmospheric pressure and low temperature (250°C). Films formed at this temperature contained Si-OH bonds, owing to inadequate dehydration. To remove the Si-OH bonds at low temperature, the sample was dipped in ethanol at room temperature for 15 min then annealed on a hot plate at 250°C in methanol gas for 30 min. This treatment effectively dissociated the Si-OH bonds. It is believed the Si-OH bonds are replaced by Si-OCH3 bonds during the alcohol-assisted annealing. The leakage current of the metal-oxide-semiconductor after alcohol-assisted annealing was improved and the hysteresis width was reduced. This indicated that the number of trap sites owing to Si-OH bonds was reduced.

Ito, Takuya; Ota, Yasuyuki; Shiomori, Koichiro; Nishioka, Kensuke

2014-04-01

392

Glucose oxidation in a dual hollow fiber bioreactor with a silicone tube oxygenator.  

PubMed

A dual hollow fiber bioreactor, consisting of an outer silicone membrane for oxygen supply and an inner polyamide membrane for substrate permeation, was used as an immobilized enzyme reactor to carry out enzymatic glucose oxidation. Attaching a silicone tube oxygenator to provide an additional oxygen supply improved the conversion in glucose oxidation when the oxygen supply was rate-limiting. The reactor was operated in both diffusion and ultrafiltration modes. In the latter case, the conversion was much higher, but the stability of the immobilized enzyme was better maintained in the diffusion mode. As the inlet glucose concentration increased from 10mM to 500mM, the conversion decreased from 70 to 20%. PMID:18576485

Chang, H N; Kyung, Y S; Chung, B H

1987-04-01

393

Three-dimensional design and replication of silicon oxide nanostructures using an atomic force microscope  

NASA Astrophysics Data System (ADS)

Atomic force microscope (AFM) based local anodic oxidation of metallic and semiconducting layers has emerged as a powerful tool for nanoscale fabrication. A unique nanoscale patterning technique has been created that couples computer aided design (CAD) with the lithographic capabilities of the AFM. Target nanostructures to be deposited on a silicon substrate are rendered as a three-dimensional model. Using AFM based local anodic oxidation on a silicon substrate, the features are duplicated at the nanoscale using voltage bias, probe speed, and humidity modulation, as prescribed by the model. The work presented herein highlights the advantages when three-dimensional modeling is linked with nanolithography; nanoscale features can be precisely replicated from a design plan.

Johannes, Matthew S.; Cole, Daniel G.; Clark, Robert L.

2007-08-01

394

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

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 (800-1000°C) 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

Boron and silicon adsorption on an aluminum oxide  

Microsoft Academic Search

Boron and Si adsorption on the Al oxide, alon (delta-AlâOâ), were investigated under changing conditions of pH, total solution anion concentration, reaction time, and order of anion addition. Boron adsorption increased at low pH, exhibited a peak near pH 8, and decreased at high pH. The constant capacitance model was successfully used to describe B adsorption over the pH range

S. Goldberg; R. A. Glaudbig

2009-01-01

397

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

398

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

399

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

400

${\\\\bf SiO}_{\\\\bm x}$ 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

401

Model and Observations of Dielectric Charge in Thermally Oxidized Silicon Resonators  

Microsoft Academic Search

This paper investigates the effects of dielectric charge on resonant frequency in thermally oxidized silicon resonators hermetically encapsulated using ??epi-seal.?? SiO2 coatings are effective for passive temperature compensation of resonators but make the devices more susceptible to charging-related issues. We present a theoretical model for the electromechanical effects of charge trapped in the dielectrics within the transduction gap of a

Gaurav Bahl; Renata Melamud; Bongsang Kim; Saurabh A. Chandorkar; James C. Salvia; Matthew A. Hopcroft; David Elata; Robert G. Hennessy; Rob N. Candler; Roger T. Howe; Thomas W. Kenny

2010-01-01

402

Microcontact printed poly(amidoamine) dendrimer monolayers on silicon oxide surface  

Microsoft Academic Search

Patterning of silicon substrates with poly(amidoamine) generation 5 (PAMAM-G5) dendrimers using soft lithographic microcontact printing (?CP) is presented. ?CP is shown to yield monolayers of dendrimers patterned with high level of definition over ?m2 to mm2 areas. The patterns are stable over a period of weeks, which is attributed to the suppressed diffusion of partially charged G5 PAMAM on oxidized

Nikodem Tomczak; G. Julius Vancso

2007-01-01

403

Fabrication and characterization of a silicon metal-oxide-semiconductor based triple quantum dot  

NASA Astrophysics Data System (ADS)

We fabricate electrostatically defined, few-electron triple quantum dot (TQD) devices in a silicon metal-oxide-semiconductor structure and obtain stability diagrams in the few-electron regime through charge detection by a nearby quantum point contact. We demonstrate the tunability of the TQD by achieving the quadruple points where all three dots are on resonance. The tuning evolutions are shown to be consistent with a constant interaction model. We identify quantum cellular automata phenomena near the quadruple point.

Pan, H.; House, M. G.; Hao, X.; Jiang, H. W.

2012-06-01

404

Structural property of polycrystalline silicon films on aluminum-doped zinc oxide-coated glass  

Microsoft Academic Search

The structural properties of crystalline silicon (Si) films on bare and aluminum-doped zinc oxide (AZO)-coated glass substrates were comparatively investigated by X-ray diffractometer, Raman spectroscopy, and transmission electron microscope. It was observed that for the amorphous Si (a-Si) films on bare and AZO-coated glass substrates subjected to five-step rapid thermal annealing (RTA) at 750°C\\/60s, they were both polycrystalline in nature

Weiyan Wang; Jinhua Huang; Xianpeng Zhang; Ye Yang; Ruiqin Tan; Weijie Song

2011-01-01

405

Kinetics of chromium oxide reduction from a basic steelmaking slag by silicon dissolved in liquid iron  

Microsoft Academic Search

The reduction of chromium oxide from a basic steelmaking slag (45 wt pct CaO, 35 wt pct SiO2, 10 wt pct MgO, 10 wt pct A12O3) by silicon dissolved in liquid iron at steelmaking temperatures was studied to determine the rate-limiting steps. The reduction\\u000a is described by the reactions: (Cr2O3) + Si = (SiO2) + (CrO) + Cr [1] and

James W. Robison; Robert D. Pehlke

1974-01-01

406

Optimized silicon-rich oxide (SRO) deposition process for 5 V only flash EEPROM applications  

Microsoft Academic Search

A process for depositing in-situ very-thin (<10 nm) SiO2 films on top of a silicon-rich oxide (SRO) layer in a standard low-pressure chemical vapor deposition (LPCVD) reactor has been optimized. Polysilicon-gate MOS capacitors using this stacked dielectric have shown high tunneling current at low voltages and an extraordinary endurance to electrical stress. Capacitors with 7 nm LPCVD SiO2 on top

Leonello Dori; Alexandre Acovic; Donelli J. DiMaria; Ching-Hsiang Hsu

1993-01-01

407

Performance evaluation of a Nafion\\/silicon oxide hybrid membrane for direct methanol fuel cell  

Microsoft Academic Search

Nafion\\/silicon oxide composite membranes were produced via the in situ acid-catalyzed sol–gel reaction of tetraethylorthosilicate (TEOS) in Nafion perfluorosulfonic acid films. The TEOS uptake content of a composite membrane was varied according to the sol–gel reaction time. The physicochemical properties of the composite membranes were investigated by FT-IR. The water uptake contents and the thermal properties of the composite membrane

D. H. Jung; S. Y. Cho; D. H. Peck; D. R. Shin; J. S. Kim

2002-01-01

408

The charging and discharging of high-voltage stress-generated traps in thin silicon oxide  

Microsoft Academic Search

Excess high-voltage stress-generated low-level leakage currents through 10 nm silicon oxides, previously described as DC currents, are shown to decay to the limit of detection given adequate observation time and, thus, have no discernible component. A physical model is presented which describes the majority of the excess low-level leakage currents in terms of the charging and discharging of traps previously

R. S. Scott; D. J. Dumin

1996-01-01

409

The Electrochemical Oxidation and Dissolution of Silicon in AN Acetonitrile-Hydrogen Fluoride Electrolyte  

Microsoft Academic Search

The electrochemical characteristics of both n -Si and p-Si were investigated. The etch rate and photocurrent for n-Si in an anhydrous, HF-acetonitrile solution were directly proportional to light intensity. Four electrons were transferred per silicon oxidized with a quantum yield (the number of electrons measured in the external circuit per photon absorbed) greater than 3.3 due to electron injection. The

Eric Keith Propst

1994-01-01

410

Electric isolation of porous silicon by electro generated polyethyleneimine film, comparison to thermal oxide  

Microsoft Academic Search

Electrochemical oxidation of diethylenetriamine (DETA) charged with 0.1 M LiSO3CF3, leads to a polymeric coating (polyethyleneimine film: PEI) on the porous silicon (PS) surface. The obtained passivated electrode is characterized through IRTF spectrometry and through C(V) curves on PS\\/PEI structures showing good insulating properties of the PEI film. The passivated electrode presents a linear pH sensitivity close to 62 mV

Omrani Meskini; Ridha M'ghaieth; Guillaume Herlem; Bernard Fahys; Adnane Abdelghani; Nicole Jaffrezic-Renault; Laurence Ponsonnet

2006-01-01

411

Internal stresses and adhesion of thin silicon oxide coatings on poly(ethylene terephthalate)  

Microsoft Academic Search

The effect of internal stresses on the cohesion and adhesion of a thin silicon oxide (SiOx) oxygen-barrier coating, evaporated on a poly(ethylene terephthalate) (PET) film substrate was studied. Internal stresses were generated during annealing in the temperature range for recrystallization of the PET,during calendering in a multilayer structure where two SiOx \\/PET films were laminated together with a polypropylene film,

Y. Leterrier; J.-A. E. Månson; Y. Wyser

2001-01-01

412

High quality plasma enhanced chemical vapour deposited silicon oxide gas barrier coatings on polyester films  

Microsoft Academic Search

Silicon oxide barrier coatings fabricated by a plasma enhanced chemical vapour deposition roll-to-roll process on polyester film have demonstrated impressive properties as a barrier to water vapour permeation. This study highlights the influence of the substrate on these coatings as we find that heat stabilised poly(ethylene terephthalate) (PET), with or without an additional acrylate primer layer, and poly(ethylene naphthalate) (PEN)

D. G. Howells; B. M. Henry; J. Madocks; H. E. Assender

2008-01-01

413

Plasma-deposited silicon oxide barrier films on polyethersulfone substrates: temperature and thickness effects  

Microsoft Academic Search

Silicon oxide (SiOx) films deposited on flexible polyethersulfone (PES) substrates by plasma-enhanced chemical vapor deposition (PEVCD) have been investigated for transparent barrier applications. Although the water vapor transmission rate (WVTR) of PES (?28 g\\/m2\\/day; thickness: 200 ?m) is higher than that of the polyethylene terephthalate (PET; ?16 g\\/m2\\/day; thickness: 188 ?m), the PES substrate can withstand process temperatures of up

D. S. Wuu; W. C. Lo; C. C. Chiang; H. B. Lin; L. S. Chang; R. H. Horng; C. L. Huang; Y. J. Gao

2005-01-01

414

Insitu investigation of the optoelectronic properties of transparent conducting oxide\\/amorphous silicon interfaces  

Microsoft Academic Search

Transparent conducting oxide (TCO)\\/hydrogenated amorphous silicon (a-Si:H) interfaces are investigated combining kinetic ellipsometry and Kelvin probe measurements. It is shown that the correlation between both insitu techniques allows a detailed description of the optoelectronic behavior of these interfaces. The Schottky barrier at the TCO\\/a\\/Si:H interfaces, as revealed by Kelvin probe measurements, is correlated with the chemical reduction of the TCO

B. Drevillon; Satyendra Kumar; P. Roca i Cabarrocas; J. M. Siefert

1989-01-01

415

Memory effects in metal-oxide-semiconductor capacitors incorporating dispensed highly monodisperse 1 nm silicon nanoparticles  

Microsoft Academic Search

Metal-oxide-semiconductor capacitors containing various densities of ex situ produced, colloidal, highly monodisperse, spherical, 1 nm silicon nanoparticles were fabricated and evaluated for potential use as charge storage elements in future nonvolatile memory devices. The capacitance-voltage characteristics are well behaved and agree with similarly fabricated zero-nanoparticle control samples and with an ideal simulation. Unlike larger particle systems, the demonstrated memory effect

Osama M. Nayfeh; Dimitri A. Antoniadis; Kevin Mantey; Munir H. Nayfeh

2007-01-01

416

Microstructural changes in silicon thermal oxide induced by high-flux copper negative-ion implantation  

Microsoft Academic Search

Silicon-thermal-oxide (a-SiO2) films of 115 nm thick on Si wafers are implanted by high-flux Cu negative-ions of 60 keV. Optical reflectivity measurements show that the Si substrates are transformed into an amorphous-like state after the implantation. The “amorphization” is ascribed to recoil atoms, not directly to the incident Cu ions. The crystallinity is recovered after a heat treatment at 900°C

H. Amekura; N. Umeda; N. Okubo; C. G Lee; Y. Takeda; N. Kishimoto

2001-01-01

417

Mechanical anomaly impact on metal-oxide-semiconductor capacitors on flexible silicon fabric  

NASA Astrophysics Data System (ADS)

We report the impact of mechanical anomaly on high-?/metal-oxide-semiconductor capacitors built on flexible silicon (100) fabric. The mechanical tests include studying the effect of bending radius up to 5 mm minimum bending radius with respect to breakdown voltage and leakage current of the devices. We also report the effect of continuous mechanical stress on the breakdown voltage over extended periods of times.

Ghoneim, M. T.; Kutbee, A.; Ghodsi Nasseri, F.; Bersuker, G.; Hussain, M. M.

2014-06-01

418

Notch Root Oxide Formation During Fatigue of Polycrystalline Silicon Structural Films  

Microsoft Academic Search

This paper investigates the fatigue behavior of n+-type 2-mum- thick polycrystalline silicon films that exhibit an initially thin (~2-3 nm) native oxide layer. The testing of kilohertz-frequency resonators provided accurate stress-life fatigue data at 30 and 50% relative humidity (RH) in the low (< 106)and high (up to 1011) cycle regimes. Long fatigue life specimens were associated with larger decreases

Olivier N. Pierron; Christopher L. Muhlstein

2007-01-01

419

Combustion of Binary and Ternary Silicon\\/Oxidant Pyrotechnic Systems, Part IV: Kinetic Aspects  

Microsoft Academic Search

Abstract–Kinetic parameters for the processes occurring during controlled heating and during combustion of the binary silicon-fuelled pyrotechnic systems. Si\\/Fe2O3, Si\\/SnO2. Si\\/Sb203 and SilKN03 have been estimated,where possible, from the results of both thermal analysis and temperature profile measurements. The values obtained from the two very different techniques are compared and discussed, and the role of the oxidant, in a series

R. ANIL RUGUNANAN; MICHAEL E. BROWN

1993-01-01

420

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 2.9×109 Pa.

Lau, H. W.; Tan, O. K.

2006-03-01

421

Performance of a biomimetic oxidation catalyst immobilized on silicon wafers: comparison with its gold congener.  

PubMed

With the aim of extending the usefulness of an existing biomimetic catalytic system, cobalt porphyrin catalytic units with thiol linkers were heterogenized via chemical grafting to silicon wafers and utilized for the catalytic oxidation of hydroquinone to p-benzoquinone. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the morphology and composition of the heterogeneous catalyst. The results of the catalytic oxidation of hydroquinone obtained with porphyrins grafted on silicon were compared with those obtained earlier with the same catalyst in homogeneous phase and immobilized on gold. It was found that the catalysis could run over 400 h, without showing any sign of deactivation. The measured catalytic activity is at least 10 times higher than that measured under homogeneous conditions, but also 10 times lower than that observed with the catalytic unit immobilized on gold. The reasons of this discrepancy are discussed in term of substrate influence and overlayer organization. The silicon-immobilized catalyst has potential as an advanced functional material with applications in oxidative heterogeneous catalysis of organic reactions, as it combines long-term relatively high activity with low cost. PMID:20973581

Eriksson, Kristofer L E; Chow, Winnie W Y; Puglia, Carla; Bäckvall, Jan-Erling; Göthelid, Emmanuelle; Oscarsson, Sven

2010-11-01

422

Near-infrared silicon quantum dots metal-oxide-semiconductor field-effect transistor photodetector  

Microsoft Academic Search

A fully silicon-based metal-oxide-semiconductor field-effect transistor is demonstrated for the detection of near-infrared light. Si nanocrystals (nc-Si) are synthesized in the nanopore channels of mesoporous silica (MS) inserted between two oxide layers to form a complete gate structure of polycrystalline Si\\/SiO2\\/nc-Si-in-MS\\/SiO2 with a polycrystalline Si electrode. Illuminating the gate with near-infrared light, a photoresponsivity as high as 2.8 A\\/W at

Jia-Min Shieh; Wen-Chien Yu; Jung Y. Huang; Chao-Kei Wang; Bau-Tong Dai; Huang-Yan Jhan; Chih-Wei Hsu; Hao-Chung Kuo; Fu-Liang Yang; Ci-Ling Pan

2009-01-01

423

Effect of ion-plated films of germanium and silicon on friction, wear, and oxidation of 52100 bearing steel  

NASA Technical Reports Server (NTRS)

Friction and wear experiments were conducted with ion plated films of germanium and silicon on the surface of 52100 bearing steel both dry and in the presence of mineral oil. Both silicon and germanium were found to reduce wear, with germanium being more effective than silicon. An optimum film thickness of germanium for minimum wear without surface crack formation was found to be approximately 400 nanometers (4000 A). The presence of silicon and germanium on the 52100 bearing steel surface improved resistance to oxidation.

Buckley, D. H.; Spalvins, T.

1977-01-01

424

Novel electrode for electrochemical stripping analysis based on carbon paste modified with bismuth powder  

Microsoft Academic Search

Bismuth-powder modified carbon paste electrode (Bi-CPE) is presented as an attractive “mercury-free” sensor applicable in electrochemical striping analysis of selected heavy metals. The electrode paste was prepared as a mixture of finely powdered metallic bismuth together with graphite powder and silicon oil. The Bi-CPE was characterized in nondeaerated solutions containing Cd(II) and Pb(II) at the ?g\\/L level in conjunction with

Samo B. Ho?evar; Ivan Švancara; Karel Vyt?as; Božidar Ogorevc

2005-01-01

425

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

426

Kinetics of oxidation of carbon in liquid iron-carbon-silicon-manganese-sulfur alloys by carbon dioxide in nitrogen  

Microsoft Academic Search

The oxidation of carbon with the simultaneous oxidation of silicon, manganese, and iron of liquid alloys by carbon dioxide\\u000a in nitrogen and the absorption of oxygen by the alloys from the gas were studied using 1-g liquid iron droplets levitated\\u000a in a stream of the gas at 1575 C to 1715 C. Oxidation of carbon was favored over oxidation of

Haiping Sun; Robert D. Pehlke

1995-01-01

427

Alternating current surface photovoltage in thermally oxidized chromium-contaminated n-type silicon wafers  

NASA Astrophysics Data System (ADS)

We investigated a variation of frequency-dependent alternating current (AC) surface photovoltages (SPVs) in thermally oxidized, chromium-contaminated, n-type silicon (Si) wafers. As previously reported, immediately after rinsing in Cr-contaminated solution, a Cr(OH)3-Si contact causes a Schottky-barrier-type AC SPV on n-type Si. Upon oxidation at 373 K for 10 min, the Schottky barrier collapses and, with further oxidation, a metal-induced negative oxide charge, due to atomic bridging of (CrOSi)- and/or CrO2- networks, definitely grows over time in SiO2. For samples oxidized at temperatures between 823 and 1023 K for 30 min, the observed AC SPV gives evidence that the metal-induced negative oxide charge causes a strongly inverted state of the Si surface. At oxidation temperatures higher than 1023 K and /or for an oxidation time longer than 60 min, the level height of the AC SPV is reduced, implying that the strongly inverted state changes into a less depleted state, whilst, finally, the AC SPV disappears. In this case, the collapse of the (CrOSi)- and/or CrO2- networks is anticipated, with a possible change into Cr2O3. The existence of the (CrOSi)- and/or CrO2- networks has also been confirmed in p-type Si wafers.

Shimizu, Hirofumi; Nagase, Shintarou; Ikeda, Masanori

2011-09-01

428

Valley polarization in bismuth  

NASA Astrophysics Data System (ADS)

The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth [1], a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.[4pt] [1] Zengwei Zhu, Aurélie Collaudin, Benoît Fauqué, Woun Kang and Kamran Behnia Nature Physics 8, 89-94 (2011)

Fauque, Benoit

2013-03-01

429

Scalable 2-bit silicon?oxide?nitride?oxide?silicon (SONOS) memory with physically separated local nitrides under a merged gate  

NASA Astrophysics Data System (ADS)

A physically separated 2-bit SONOS memory with a single gate is fabricated for the first time. By forming physically separated 30-nm twin ONOs with an inverted sidewall spacer patterning method and damascene process under a merged-triple gate, the decrease of charge distribution and diffusion during and after CHEI (channel hot electron injection) program in 2-bit operation of the localized trap memory is observed in devices with the gate length of 90 nm. The inverted amorphous silicon spacer and the damascene gate process does not suffer from unit-cell size increase, lithographic resolution limit, and miss-alignment between gate and ONOs. Comparing with a conventional single SONOS memory (SSM), this novel twin SONOS memory (TSM) cell can maintain the better control of trapped charge distribution due to the strong diffusion barrier of charges. As a result, better 2-bit operation, endurance and retention than SSM, and absence of disturbance can be obtained in the short (sub 90 nm) gate length devices.

Lee, Yong Kyu; Sung, Suk Kang; Sim, Jae Sung; Song, Ki Whan; Lee, Jong Duk; Park, Byung-Gook; Kang, Sung Taeg; Chung, Chilhee; Park, Donggun; Kim, Kinam

2004-11-01

430

Structural silicon nitride materials containing rare earth oxides  

DOEpatents

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

Andersson, Clarence A. (Pittsburgh, PA)

1980-01-01

431

Enhanced silicon oxidation on titanium-covered Si(001).  

PubMed

We report on a core level photoemission study of the formation of an ultrathin SiO(x) layer grown at the interface of a titanium-covered Si(001) surface. Oxygen exposure at room temperature induces a large chemical shift of the Si 2p state, predominantly assigned to Si(4+). The results indicate that a SiO(2 - ?) layer, close to the stoichiometry of SiO(2), is formed below the TiO(x) film. The thickness of the SiO(2 - ?) layer is estimated to be ? 0.9 nm, corresponding to three to four oxide layers. Further chemical shift caused by annealing is attributed to the formation of titanium silicate (TiSi(x)O(y)). PMID:21709355

Ohno, S; Shudo, K; Nakayama, F; Yamazaki, K; Ichikawa, Y; Tanaka, M; Okuda, T; Harasawa, A; Matsuda, I; Kakizaki, A

2011-08-01

432

A proteomic approach for the identification of bismuth-binding proteins in Helicobacter pylori.  

PubMed

Helicobacter pylori is a major human pathogen that can cause peptic ulcers and chronic gastritis. Bismuth-based triple or quadruple therapies are commonly recommended for the treatment of H. pylori infections. However, the molecular mechanisms underlying treatment with bismuth are currently not fully understood. We have conducted a detailed comparative proteomic analysis of H. pylori cells both before and after treatment with colloidal bismuth subcitrate (CBS). Eight proteins were found to be significantly upregulated or downregulated in the presence of CBS (20 microg mL(-1)). Bismuth-induced oxidative stress was confirmed by detecting higher levels of lipid hydroperoxide (approximately 1.8 times) and hemin (approximately 3.4 times), in whole cell extracts of bismuth-treated H. pylori cells, compared with those from untreated cells. The presence of bismuth also led to an approximately eightfold decrease in cellular protease activities. Using immobilized-bismuth affinity chromatography, we isolated and subsequently identified seven bismuth-binding proteins from H. pylori cell extracts. The intracellular levels of four of these proteins (HspA, HspB, NapA and TsaA) were influenced by the addition of CBS, which strongly suggests that they interact directly with bismuth. The other bismuth-interacting proteins identified were two enzymes (fumarase and the urease subunit UreB), and a translational factor (Ef-Tu). Our data suggest that the inhibition of proteases, modulation of cellular oxidative stress and interference with nickel homeostasis may be key processes underlying the molecular mechanism of bismuth's actions against H. pylori. PMID:17503094

Ge, Ruiguang; Sun, Xuesong; Gu, Qing; Watt, Rory M; Tanner, Julian A; Wong, Benjamin Chun Yu; Xia, Harry Huaxiang; Huang, Jian-Dong; He, Qing-Yu; Sun, Hongzhe

2007-08-01

433

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-Félicie; Lacaze, Emmanuelle; Chabal, Yves J; Pluchery, Olivier

2013-04-23

434

A kinetic Monte Carlo study of the initial stage of silicon oxidation: Basic mechanisms-induced partial ordering of the oxide interfacial layer  

Microsoft Academic Search

A kinetic Monte Carlo study of the early stage of silicon oxidation is presented. The model assembles the most recently published dedicated surface mechanisms: oxygen incorporations, migrations, charge transfer effects. Simulations of the thermal oxidation at typical manufacturing temperature and pressure conditions are discussed. As revealed recently through Density Functional Theory investigations, we observe hexagonal patterns that can be here

Anne Hémeryck; Alain Estève; Nicolas Richard; Mehdi Djafari Rouhani; Georges Landa

2009-01-01

435

From germanium nanowires to germanium-silicon oxide nanotubes: influence of germanium tetraiodide precursor.  

PubMed

Growth of semiconductor nanowires has attracted immense attention in the field of nanotechnology as nanowires are viewed as the potential basic building blocks of future electronics. The recent renewed interest in germanium as a material for nanostructures can be attributed to its higher carrier mobility and larger Bohr radius as compared to silicon. Self-assembly synthesis of germanium nanowires (GeNWs) is often obtained through a vapor-liquid-solid mechanism, which is essentially a catalytic tip-growth process. Here we demonstrate that by introducing an additional precursor, germanium tetraiodide (GeI(4)), in a conventional furnace system that produces GeNWs on silicon, tubular structures of germanium-silicon (GeSi) oxide can be obtained instead. Incorporation of GeI(4) results in passivation of the metal catalyst, preventing the occurrence of supersaturation, a prerequisite for the catalytic tip growth. We infer that passivation of the metal catalyst impedes Ge incorporation into the catalyst, leaving the catalyst rim as the only active sites for nucleation of both Si and Ge and thus resulting in the growth of GeSi oxide nanotubes via a root-growth process. PMID:19146456

Huang, Jinquan; Chim, Wai Kin; Wang, Shijie; Chiam, Sing Yang; Wong, Lai Mun

2009-02-01

436

Optical gain in dye-doped polymer waveguides using oxidized porous silicon cladding  

NASA Astrophysics Data System (ADS)

We report on a novel organic/inorganic hybrid waveguide approach, which is composed of a cladding of extremely low refractive index oxidized porous silicon formed on a bulk silicon substrate and of it, a polymeric (polymethylmethacrylate) core doped with a visible laser dye (Nile-Blue) was deposited by spin coating. The waveguiding properties of the structures have been characterised by means of the m-line technique, demonstrating that the use of oxidized porous silicon as a cladding can considerably improve the mode confinement factor of single-mode waveguides. The low refractive index achievable in the cladding (n=1.16) allows forming waveguides with a low index polymer cores. Variable stripe length (VSL) measurements have been also performed in order to characterise the amplification properties of the waveguides. We demonstrate a clear transition from losses to gain at 694nm with a pump threshold of 28mJ/cm2. Values of net optical gain up to 104dB/cm have been measured at this wavelength.

Navarro-Urrios, Daniel; Ghulinyan, Mher; Bettotti, Paolo; Capuj, Néstor; Oton, Claudio J.; Lahoz, Fernando; Martin, Inocencio R.; Pavesi, Lorenzo

2007-05-01

437

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 Cdbnd C and Ctbnd C 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, Jürgen; Haick, Hossam; Christiansen, Silke H.

2013-02-01

438

Thick oxidized porous silicon layer as thermo-insulating material for high temperature operating thin and thick film gas sensors  

Microsoft Academic Search

Thick oxidized porous silicon layers (OPS), with thickness ranging from 5 to 35 ?m, have been realized on p+ Si substrates using Si anodization followed by thermal oxidation. A mesoporous Si structure with a 55% porosity has been selected as starting material. Phosphorus implantation of a patterned p+ Si substrate has been performed to take advantage of the selective anodization

P. Maccagnani; R. Angelucci; P. Pozzi; A. Poggi; L. Dori; G. C. Cardinali; P. Negrini

1997-01-01

439

Transparent conducting oxides (TCO{close_quote}s) for amorphous silicon solar cells  

SciTech Connect

The stability of various textured tin oxide and zinc oxide transparent conductors was evaluated against annealing in air, in vacuum or exposed to hydrogen plasma. Only fluorine-doped zinc oxide deposited by atmospheric pressure chemical vapor deposition (APCVD) had stable electrical and optical properties under all conditions. Thin layers of ZnO or TiO{sub 2} greatly improved the plasma resistance of SnO{sub 2}. A new TCO material, niobium-doped titanium dioxide (TiO{sub 2}:Nb) was able to withstand hydrogen plasmas with only slight increases in its optical absorption and conductivity. Composite TCO{close_quote}s consisting of glass/SnO{sub 2}:F/TiO{sub 2}:Nb were shown to provide good electrical contact to amorphous silicon solar cells. {copyright} {ital 1996 American Institute of Physics.}

Hegedus, S. [Institute of Energy Conversion, University of Delaware, Newark, Delaware 19716 (United States); Liang, H.; Gordon, R.G. [Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138 (United States)

1996-01-01

440

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

441

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

PubMed Central

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.

2013-01-01

442

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

443

Hydrogen passivation of silicon(100) used as templates for low-temperature epitaxy and oxidation  

NASA Astrophysics Data System (ADS)

Epitaxial growth, oxidation and ohmic contacts require surfaces as free as possible of physical defects and chemical contaminants, especially, oxygen and hydrocarbons. Wet chemical cleaning typically involves a RCA clean to remove contaminants by stripping the native oxide and regrowing a chemical oxide with only trace levels of carbon and metallic impurities. Low temperature epitaxy, T<800sp° C, limits the thermal budget for the desorption of impurities and surface oxides, and can be performed on processed structures. But, silicon dioxide cannot be desorbed at temperatures lower than 800sp°C. Recently, hydrogen passivation of Si(111) has been reported to produce stable and ordered surfaces at low temperatures. Hydrogen can then be desorbed between 200sp°C and 600sp°C prior to deposition. In this work, Si(100) is passivated via a solution of hydrofluoric acid in alcohol (methanol, ethanol, or isopropyl alcohol) with HF concentrations between 0.5 to 10%. A rinse in water or alcohol is performed after etching to remove excess fluorine. This work investigates wet chemical cleaning of Si(100) to produce ordered, hydrogen-terminated, oxygen- and carbon-free surfaces to be used as templates for low temperature epitaxial growth and rapid thermal oxidation. Ion beam analysis, Tapping mode atomic force microscopy, Fourier transform infrared spectroscopy, Secondary ion mass spectroscopy, Chemical etching, Capacitance-voltage measurements and Ellipsometry are used to measure, at the surface and interface, impurities concentration, residual disorder, crystalline order, surface topography, roughness, chemical composition, defects density, electrical characteristics, thickness, and refractive index as a function of cleaning conditions for homoepitaxial silicon growth and oxidation. The wetting characteristics of the Si(100) surfaces are measured with a tilting plate technique. Different materials are analyzed by ion beam analysis for use as hydrogen standards in elastic recoil detection of hydrogen on sample surfaces. The results obtained in this study provide a quantitative optimization of passivation of Si(100) surfaces and their use as templates for low temperature epitaxy and rapid thermal oxidation. Ion beam analysis shows that the total coverage of H increases during passivation of Si(100) via HF in alcohol, while Fourier transform infrared spectroscopy indicates that more complex termination than the formation of simple silicon hydrides occurs.

Atluri, Vasudeva Prasad

444

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

445

Performance analysis of silicon nanowire transistors considering effective oxide thickness of high-k gate dielectric  

NASA Astrophysics Data System (ADS)

We have analyzed the effective oxide thickness (EOT) of the dielectric material for which we have optimum performance and the output characteristics of the silicon nanowire transistors by replacing the traditional SiO2 gate insulator with a material that has a much higher dielectric constant (high-k) gate, materials like Si3N4, Al2O3, Y2O3 and HfO2. We have also analyzed the channel conductance, the effect of a change in thickness, the average velocity of the charge carrier and the conductance efficiency in order to study the performance of silicon nanowire transistors in the nanometer region. The analysis was performed using the Fettoy, a numerical simulator for ballistic nanowire transistors using a simple top of the barrier (Natori) approach, which is composed of several matlab scripts. Our results show that hafnium oxide (HfO2) gate insulator material provides good thermal stability, a high recrystallization temperature and better interface qualities when compared with other gate insulator materials; also the effective oxide thickness of HfO2 is found to be 0.4 nm.

Chandra, S. Theodore; Balamurugan, N. B.

2014-04-01

446

High-performance silicon photoanodes passivated with ultrathin nickel films for water oxidation.  

PubMed

Silicon's sensitivity to corrosion has hindered its use in photoanode applications. We found that deposition of a ~2-nanometer nickel film on n-type silicon (n-Si) with its native oxide affords a high-performance metal-insulator-semiconductor photoanode for photoelectrochemical (PEC) water oxidation in both aqueous potassium hydroxide (KOH, pH = 14) and aqueous borate buffer (pH = 9.5) solutions. The Ni film acted as a surface protection layer against corrosion and as a nonprecious metal electrocatalyst for oxygen evolution. In 1 M aqueous KOH, the Ni/n-Si photoanodes exhibited high PEC activity with a low onset potential (~1.07 volts versus reversible hydrogen electrode), high photocurrent density, and durability. The electrode showed no sign of decay after ~80 hours of continuous PEC water oxidation in a mixed lithium borate-potassium borate electrolyte. The high photovoltage was attributed to a high built-in potential in a metal-insulator-semiconductor-like device with an ultrathin, incomplete screening Ni/NiO(x) layer from the electrolyte. PMID:24233719

Kenney, Michael J; Gong, Ming; Li, Yanguang; Wu, Justin Z; Feng, Ju; Lanza, Mario; Dai, Hongjie

2013-11-15

447

Development of silicon electrode enhanced by carbon nanotube and gold nanoparticle composites on silicon neural probe fabricated with complementary metal-oxide-semiconductor process  

NASA Astrophysics Data System (ADS)

We present the fabrication of highly P-doped single crystal silicon electrodes on a silicon probe through complementary metal-oxide-semiconductor (CMOS)-compatible processes. The electrode with diameter of 50 ?m and a separation of 200 ?m is designed for recording/stimulating purposes. Electrochemical impedance spectroscopy indicates that the interfacial impedance of silicon electrodes at 1 KHz is 2.5 ± 0.4 M?, which is equivalent to the result reported from the gold (Au) electrode. To further enhance the charge storage capacity, composites of multi-wall carbon nanotubes (MWCNTs) and Au nanoparticles are electroplated onto the highly P-doped silicon electrode after surface roughness treatments. With optimized electroplating processes, MWCNTs and Au nanoparticles are selectively coated onto the electrode site with only a minimum enlargement in physical diameter of electrode (<10%). However, the typical impedance is reduced to 21 ± 3 k?. Such improvement can be explained by a boost in double-layer capacitance (Cdl) and the reduction in faradic resistances. The measurement of cyclic voltammetry (CV) shows that the cathodal charge storage capacity is up to 35 mC cm-2, which proves the superior performance of composite coatings on silicon electrodes and validates the functionality of reported CMOS-compatible silicon probe.

Zhang, Songsong; Tsang, Wei Mong; Srinivas, Merugu; Sun, Tao; Singh, Navab; Kwong, Dim-Lee; Lee, Chengkuo

2014-05-01

448

Pull-test adhesion measurements of diamondlike carbon films on silicon carbide, silicon nitride, aluminum oxide, and zirconium oxide  

SciTech Connect

Hydrogenated amorphous carbon films or diamondlike carbon (DLC) films were formed by ion-beam deposition of 400 eV methane (CH{sub 4}) ions on several smooth and rough ceramics, as well as on ceramics coated with a layer of Si and Ti. Adhesion was measured by the pin-pull method. Excellent adhesion was measured for smooth SiC and Si{sub 3}N{sub 4}, but adhesion of DLC to 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 because bonding between the DLC film and Ti was poor. The presence of surface roughness appeared to greatly increase the measured adhesion in all cases. Bulk thermodynamic calculations are not directly applicable to bonding at the interface. If the standard enthalpy of formation for reaction between CH{sub 4} and substrate is calculated assumpting a carbide or carbon phase is produced, a relation is seen between reaction enthalpy and 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. Lack of adhesion to Ti was attributed to inadvertent formation of a surface oxide layer that rendered the enthalpy for reaction with CH{sub 4} strongly positive and similar in magnitude to that for Al{sub 2}O{sub 3} and ZrO{sub 2}.

Erck, R.A.; Nichols, F.A. [Argonne National Lab., IL (United States); Dierks, J.F. [North Dakota State Univ., Fargo, ND (United States)

1993-10-01

449

Silicon oxide-planarized single-mode 850-nm VCSELs with TO package for 10 Gb\\/s data transmission  

Microsoft Academic Search

In this letter, we report on an alternative method to fabricate a high-efficiency planar-type oxide-confined 850-nm vertical-cavity surface-emitting lasers (VCSELs). The planarized process of VCSELs was to use the silicon oxide as the buried layer. As a result, these devices with an oxidized aperture of 3 ?m in diameter exhibit a single-transverse mode behavior throughout the operation current range. In

Chia-Lung Tsai; Feng-Ming Lee; Fu-Yi Cheng; Meng-Chyi Wu; Sum-Chien Ko; Hai-Lin Wang; Wen-Jeng Ho

2005-01-01

450

Bismuth ochers from San Diego Co., California  

USGS Publications Warehouse

The chief points brought out in this paper may be briefly summarized as follows: (1) The existence of natural Bi2O3 has not been established. (2) Natural bismite or bismuth ocher, when pure, is more probably a bismuth hydroxide. (3) The bismuth ochers from San Diego County, California, are either a bismuth hydroxide or bismuth vanadate, pucherite, or mixtures of these two. (4) Pucherite has been found noncrystallin and determined for the first time in the United States.

Schaller, W. T.

1911-01-01

451

Sinterability of magnesium silicon nitride powder with yttrium oxide addition coated using the homogeneous precipitation method  

Microsoft Academic Search

The sinterability of magnesium silicon nitride (MgSiN2) powder with yttrium oxide (Y2O3) addition was examined using the hot-pressing technique (31 MPa and N2 atmosphere) at 1550°C for 90 min; the MgSiN2 powder had been coated with 0–4 mass% of Y2O3 addition by a (urea-based) homogeneous precipitation method. Relative densities of the hot-pressed MgSiN2 compacts (ceramics) with and without Y2O3 addition

KIYOSHI ITATANI; IAN J. DAVIES; HIROAKI KUWANO; MAMORU AIZAWA

2002-01-01

452

Degradation of Gate Oxide Reliability due to Plasma-Deposited Silicon Nitride  

NASA Astrophysics Data System (ADS)

The effects of plasma-enhanced chemical vapor deposition (PE-CVD) silicon nitride (p-SiN) passivation films on time dependent dielectric breakdown (TDDB) of gate oxide were studied. It was found that degradation of TDDB characteristics with p-SiN films was suppressed by the change in p-SiN deposition conditions. The correlation between trapped electron density and TDDB characteristics varied, depending on the p-SiN films. The degradation of TDDB characteristics was also enhanced with phosphosilicate glass (PSG) under the p-SiN passivation film.

Ogino, Masaaki; Sugahara, Yoshiyuki; Kuribayashi, Hitoshi; Yamabe, Kikuo

2004-03-01

453

Impact of thermal oxidation, surface chemistry and porous silicon morphology for sensing applications  

NASA Astrophysics Data System (ADS)

An ideal diagnostic device should be inexpensive, easy-to-use, rapid and reliable. Nanostructured porous silicon (PSi) satisfies these criterions including label-free optical detection and high throughput detection. Pore morphology (size, porosity) must be tailored for each specific application, and for immunosensing applications PSi morphology has been optimized for maximal pore infiltration of larger proteins as immuno gamma globlulin (IgG). Sensor degradation by high salt concentration induces a baseline drift. Different thermal oxidation procedures have been studied in order to obtain a stable sensor in the 3 hour incubation period of the immunoassay with negligible drift

Kolmychek, I. A.; Kopylov, D. A.; Murzina, T. V.; Baldini, F.; Berneschi, S.; Farnesi, D.; Giannetti, A.; Tombelli, S.; Nunzi Conti, G.; Soria, S.

2013-03-01