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1

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

Microsoft Academic Search

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

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

2011-01-01

2

Primary alkaline battery containing bismuth metal oxide  

US Patent & Trademark Office Database

A battery includes a cathode having an oxide containing one or more metals and pentavalent bismuth, an anode, a separator between the cathode and the anode, and an alkaline electrolyte. The metal(s) can be an alkali metal, an alkaline earth metal, a transition metal, and/or a main group metal. The separator can be ion-selective or capable of substantially preventing soluble bismuth ionic species from diffusing from the cathode to the anode.

2009-05-26

3

Thermoelectric Properties of Bismuth and Silicon Nanowires  

NASA Astrophysics Data System (ADS)

Thermoelectric materials convert temperature differences into electricity and vice versa. Such materials utilize the Seebeck effect for power generation and the Peltier effect for refrigeration. In the Seebeck effect, a temperature gradient across a material causes the diffusion of charged carriers across that gradient, thus creating a voltage difference between the hot and cold ends of the material. Conversely, the Peltier effect explains the fact that when current flows through a material a temperature gradient arises because the charged carriers exchange thermal energy at the contacts. Thermoelectrics perform these functions without moving parts and they do not pollute. This makes them highly reliable and more importantly attractive as renewable energy sources, especially at a time when global warming is a growing concern. However, thermoelectrics find only limited use because of their poor efficiency. The efficiency of a thermoelectric material is determined by the dimensionless figure of merit, ZT = S2k T, where S is the thermoelectric power, defined as the thermoelectric voltage, V, produced per degree temperature difference S = dVdT , sigma is the electrical conductivity, kappa is the thermal conductivity, and T is the temperature. To maximize ZT, S must be large so that a small temperature difference can create a large voltage, sigma must be large in order to minimize joule heating losses, and kappa must be small to reduce heat leakage and maintain a temperature difference. Maximizing ZT is challenging because optimizing one physical parameter often adversely affects another. The best commercially available thermoelectric devices are alloys of Bi2Te3 and have a ZT of 1 which corresponds to a cannot efficiency of ˜10%. My research has focused on achieving efficient thermoelectric performance from the single component systems of bismuth and silicon nanowires. Bismuth nanowires are predicted to undergo a semi-metal to semiconductor transition below a size of 50 nm which should increase the thermopower and thus ZT. Limited experimental evidence by other groups has been acquired to support this claim. Through electric field gating measurements and by tuning the nanowire size, we have shown that no such transition occurs. Instead, surface states dominate the electric transport at a size smaller than 50 nm and bismuth remains a semimetal. Bulk silicon is a poor thermoelectric due to its large thermal conductivity. However, silicon nanowires may have a dramatically reduced thermal conductivity. By varying the nanowire size and impurity doping levels, ZT values representing an approximately 100-fold improvement over bulk silicon are achieved over a broad temperature range, including a ZT ˜ 1 at 200K. Independent measurements of S, sigma, and kappa, combined with theory, indicate that the improved efficiency originates from phonon effects. The thermal conductivity is reduced and the thermopower is enhanced. These results are expected to apply to other classes of semiconductor nanomaterials.

Boukai, Akram Issam

4

Surface aspects of bismuth-metal oxide catalysts  

SciTech Connect

A series of conventional and model bismuth-metal oxide catalysts (vanadates, molybdates, tungstates, and niobates) were physically and chemically characterzied (Raman spectroscopy, BET, XPS, and methanol oxidation) to obtain additional insights into the structure-reactivity relationships of such catalytic materials. The reactivity for methanol oxidation over the conventional bismuth-metal oxide catalysts was found to be primarily related to the surface area of the oxide catalysts and was essentially independent of the near surface composition and the bulk structure. The selectivity for methanol oxidation over the conventional bismuth-metal oxide catalysts was essentially found not to be a function of the surface area, the near surface composition, and the bulk structure. A series of model bismuth-metal oxide catalysts was synthesized by depositing metal oxides on the surface of a bismuth oxide support. The model studies demonstrated that two-dimensional metal oxide overlayers are not stable on the bismuth oxide support and readily react to form bulk bismuth-metal oxide compounds upon heating. Furthermore, the model studies revealed that these bulk bismuth-metal oxide compounds are related to the active sites for the partial oxidation reaction. In situ Raman spectroscopy in methanol/oxygen, methanol, and oxygen reaction environments with helium as the diluent revealed no additional information regarding the nature of the active site. It was found that only highly crystalline bismuth-metal oxide phases are selective for the partial oxidation of methanol to formaldehyde. Thus, selective bismuth-metal oxide catalysts will always possess highly crystalline metal oxide phases containing extremely low surface areas which make it difficult to obtain fundamental surface information about the outermost layers. 48 refs., 11 figs., 9 tabs.

Arora, N.; Deo, G.; Wachs, I.E. [Lehigh Univ., Bethlehem, PA (United States)] [and others] [Lehigh Univ., Bethlehem, PA (United States); and others

1996-03-01

5

Bismuth based oxide electrolytes— structure and ionic conductivity  

Microsoft Academic Search

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

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

1999-01-01

6

Barium Titanate and Bismuth Oxide Nanocomposites Barium titanate, BaTiO3, and bismuth oxide Bi2O3 are transparent materials with  

E-print Network

(23), 5697 (2004). 22. "Comparative Study of Lead Borate and Bismuth Lead Borate Glass Systems as RadiationBarium Titanate and Bismuth Oxide Nanocomposites Barium titanate, BaTiO3, and bismuth oxide Bi2O3, Condensed Matter, Vol. 15, 8927 (2003). 21. "Highly Nonlinear Bismuth-Oxide Fiber for Smooth Supercontinuun

Harmon, Julie P.

7

Intrinsic stress of bismuth oxide thin films: effect of vapour chopping and air ageing  

Microsoft Academic Search

Bismuth oxide thin films of thickness 1000 A0 have been prepared by thermal oxidation (in air) of vacuum evaporated bismuth thin films (on glass substrate) at different oxidation temperatures and duration. Both the vapour chopped and nonchopped bismuth oxide thin films showed polycrystalline and polymorphic structure. The monoclinic bismuth oxide was found to be predominant in both the cases. The

R. B. Patil; R. K. Puri; V. Puri

2008-01-01

8

Aging phenomenon of stabilized bismuth oxides  

SciTech Connect

Stabilized bismuth oxides exhibit a decay in conductivity when annealed at temperatures below 600 C. The authors refer to this phenomenon as aging and it is distinct from a conventional crystallographic phase transformation. This phenomenon is revealed by an endotherm from DSC thermal analysis and results in the formation of a superstructure observable by TEM diffraction patterns, yet no change in structure is observable by XRD. Since oxygen vacancies are the mobile defects responsible for ionic conductivity, the authors attribute the aging process to the ordering of oxygen vacancies by an order-disorder transition below [approximately]600 C.

Jiang, N.; Buchanan, R.M.; Henn, F.E.G.; Marshall, A.F.; Stevenson, D.A. (Stanford Univ., CA (United States). Dept. of Materials Science and Engineering); Washsman, E.D. (SRI International, Menlo Park, CA (United States). Materials Research Center)

1994-03-01

9

Deposition and characterisation of bismuth oxide thin films  

Microsoft Academic Search

Owing to their peculiar characteristics, bismuth oxides are used in various domains, such as microelectronics, sensor technology, optical coatings, transparent ceramic glass manufacturing, etc. Bismuth oxide system exhibit high oxide ionic conductivity and have been proposed as good electrolyte materials for application, such as solid oxide fuel cell (SOFC) and oxygen sensor.Antimony doped and undoped Bi2O3 films were deposited onto

V. Fruth; M. Popa; D. Berger; R. Ramer; M. Gartner; A. Ciulei; M. Zaharescu

2005-01-01

10

Highly ytterbium-doped bismuth-oxide-based fiber.  

PubMed

Thermally stable highly ytterbium-doped bismuth-oxide-based glasses have been investigated. The absorbance increased linearly with Yb(2)O(3) concentration, reaching 7800 dB/m with 3 mol-% of Yb(2)O(3). An ytterbium-doped bismuth-oxide-based fiber has also been fabricated with a fiber loss of 0.24 dB/m. A fiber laser is also demonstrated, and it shows a slope efficiency of 36%. PMID:19654819

Ohara, Seiki; Kuroiwa, Yutaka

2009-08-01

11

Structural and optical characteristics of bismuth oxide thin films  

Microsoft Academic Search

The formation of different phases of Bi–O system during oxidizing process of Bi films from the viewpoint of structure characteristics and optical properties, is investigated. As revealed by structure and surface investigations, the thermal oxidation, in air, of Bi films on glass results in polycrystalline and multiphase bismuth oxide films. At substrate–film interface an amorphous oxide layer forms up, to

L. Leontie; M. Caraman; M. Alexe; C. Harnagea

2002-01-01

12

Degradation of organic dyes via bismuth silver oxide initiated direct oxidation coupled with sodium bismuthate based visible light photocatalysis.  

PubMed

Organic dye degradation was achieved via direct oxidation by bismuth silver oxide coupled with visible light photocatalysis by sodium bismuthate. Crystal violet dye decomposition by each reagent proceeded via two distinct pathways, each involving different active oxygen species. A comparison of each treatment method alone and in combination demonstrated that using the combined methods in sequence achieved a higher degree of degradation, and especially mineralization, than that obtained using either method alone. In the combined process direct oxidation acts as a pretreatment to rapidly bleach the dye solution which substantially facilitates subsequent visible light photocatalytic processes. The integrated sequential direct oxidation and visible light photocatalysis are complementary manifesting a > 100% increase in TOC removal, compared to either isolated method. The combined process is proposed as a novel and effective technology based on one primary material, sodium bismuthate, for treating wastewaters contaminated by high concentrations of organic dyes. PMID:22616904

Yu, Kai; Yang, Shaogui; Liu, Cun; Chen, Hongzhe; Li, Hui; Sun, Cheng; Boyd, Stephen A

2012-07-01

13

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

E-print Network

Bismuth Spheres Grown in Self-Nested Cavities in a Silicon Wafer Hong Liu, and Zhong Lin Wang-step, hydrofluoric acid-free hydrothermal etching method that not only produces bismuth nano/micrometer-sized spheres Bismuth is a semimetal with unusual electronic properties that results from its highly anisotropic Fermi

Wang, Zhong L.

14

Wettability Between Vehicle and Lead\\/Bismuth Oxide Glasses  

Microsoft Academic Search

Lead and bismuth glass systems have different wettability, which affects the mixture of the paste (vehicle and frits) and the burn-out of the vehicle within a thick film. This study examined the reaction between the vehicle (ethyl cellulose (EC) with ?-terpineol) and oxide glasses (PbO and Bi2O3 glasses). The contact angle with the vehicle on the Bi2O3 glass was found

Sangwook Lee; Dongsun Kim; Seongjin Hwang; Kyungjun Hong; Hyungsun Kim

2009-01-01

15

Silicon-bismuth and germanium-bismuth clusters of high stability.  

PubMed

Mixed metal-semiconductor clusters of the form Bi2Si(n-2) and Bi2Ge(n-2), n = 3-8, 12, are studied theoretically by ab initio methods including density functional theory with the hybrid B3LYP functional, second-order perturbation, and coupled cluster CCSD(T) theory using the doubly polarized TZV2P basis sets. These clusters are characterized by high stability and symmetry and relatively large highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps. It is shown that the lower energy structures of these clusters and their bonding and electronic characteristics are fully compatible with very powerful stability rules and structural laws similar to the ones for the corresponding isovalent boranes, carboranes, and bisboranes. This is particularly true for the Bi2Ge(n-2) clusters, the global minima of which are identical to the ones of the corresponding isovalent carboranes and bisboranes, obtained by proper substitutions from the corresponding dianions. The Bi2Si(n-2) clusters for n > 8, although isolobal to the homologous Si(n)(2-) clusters, are not fully isolobal with the corresponding boranes, carboranes, and bisboranes as the n = 3-8 clusters. For the Bi2Si(n-2) clusters with n < or = 8, a strange odd-even effect is observed. For the even-n Bi2Si(n-2) clusters, in contrast to those of odd-n, the structures obtained from the Si(n)(2-) dianions through the so-called "boron connection" compete with those obtained from substitutions on the corresponding neutral cluster structures. The even-n Bi2Si(n-2) clusters are fluxional or isomerizable. The Bi2Si4 cluster in particular is fluxional and structurally similar to the corresponding Si6 cluster. The differences between the Bi2Si(n-2) and Bi2Ge(n-2) clusters are attributed mainly to the inert pair effect in Bi2Ge(n-2). For this reason, although the lowest energy structure of the Bi2Si(10) cluster has relatively low (C(s)) symmetry derived from the corresponding Si(12)(2-) structure, the homologous Bi2Ge10 cluster is characterized by high D5d symmetry obtained from the Ge(12)(2-) dianion of full icosahedral symmetry, similar to the corresponding (B12H12)2- borane. The present rationalization of the silicon/germanium-bismuth clusters is very promising for deeper understanding and future functionalization toward useful chemical and technological applications. PMID:19799391

Zdetsis, Aristides D

2009-11-01

16

Mullite interaction with bismuth oxide from minerals and sol-gel processes F. Gridi-Bennadji *  

E-print Network

Mullite interaction with bismuth oxide from minerals and sol-gel processes F. Gridi-Bennadji * , J doped by bismuth oxide was studied by TGA and DTA, X ray diffraction, and electron microscopy (SEM and mullite, glass and Al- rich oxides are formed. Mullite exhibits an accentuated acicular morphology along 3

Paris-Sud XI, Université de

17

On the Refinement Mechanism of Silicon in Al-Si-Cu-Zn Alloy with Addition of Bismuth  

NASA Astrophysics Data System (ADS)

Obtained results of micro and nano studies reveal that bismuth refines the silicon in which the flake silicon changed to lamellar structure with reduction in twin spacing from 160 to 75 nm. Bismuth segregates towards the inter-dendritic regions and decreases the Al-Si contact angle resulting in suppression of the silicon growth causing refinement of the eutectic structure. Increased recalescence temperature and time confirmed that the refinement effect is attributed to the growth stage.

Farahany, Saeed; Ourdjini, Ali; Bakar, Tuty Asma Abu; Idris, Mohd Hasbullah

2014-01-01

18

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

2014-08-01

19

Initializing, manipulating and storing quantum information with bismuth dopants in silicon  

Microsoft Academic Search

A prerequisite for exploiting spins for quantum data storage and processing\\u000ais long spin coherence times. Phosphorus dopants in silicon (Si:P) have been\\u000afavoured as hosts for such spins because of measured electron spin coherence\\u000atimes (T2) longer than any other electron spin in the solid state: 14 ms at 7\\u000aK. Heavier impurities such as bismuth in silicon (Si:Bi)

Gavin W. Morley; Marc Warner; A. Marshall Stoneham; P. Thornton Greenland; Johan van Tol; Christopher W. M. Kay; Gabriel Aeppli

2010-01-01

20

Initializing, manipulating and storing quantum information with bismuth dopants in silicon  

Microsoft Academic Search

A prerequisite for exploiting spins for quantum data storage and processing is long spin coherence times. Phosphorus dopants in silicon (Si:P) have been favoured as hosts for such spins because of measured electron spin coherence times (T2) longer than any other electron spin in the solid state: 14 ms at 7 K. Heavier impurities such as bismuth in silicon (Si:Bi)

Gavin W. Morley; Marc Warner; A. Marshall Stoneham; P. Thornton Greenland; Johan van Tol; Christopher W. M. Kay; Gabriel Aeppli

2010-01-01

21

The initialization and manipulation of quantum information stored in silicon by bismuth dopants  

Microsoft Academic Search

A prerequisite for exploiting spins for quantum data storage and processing is long spin coherence times. Phosphorus dopants in silicon (Si:P) have been favoured as hosts for such spins because of measured electron spin coherence times (T2) longer than any other electron spin in the solid state: 14ms at 7K with isotopically purified silicon. Heavier impurities such as bismuth in

Gavin W. Morley; Marc Warner; A. Marshall Stoneham; P. Thornton Greenland; Johan van Tol; Christopher W. M. Kay; Gabriel Aeppli

2010-01-01

22

Auger electron spectroscopy and secondary-ion mass spectroscopy study of interdiffusion in gold-bismuth oxide and aluminium-bismuth oxide thin films  

Microsoft Academic Search

Thin-film bismuth oxide systems were prepared by depositing gold or aluminum on glass substrates, followed by deposition of bismuth over the gold or aluminium metal layer, after which thermal oxidation was carried out to yield a Bi2O3 layer. Auger electron spectroscopy (AES) and secondary-ion mass spectroscopy (SIMS) were performed on these thin-film systems. AES results show that the average stoichiometry

K. B. Sundaram; A. L. Grogan; S. S. Seshan

1992-01-01

23

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

24

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

25

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

Microsoft Academic Search

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

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

2002-01-01

26

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

Microsoft Academic Search

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

Jingsi Yang; Terrill B Atwater; Jun John Xu

2005-01-01

27

Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides  

SciTech Connect

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

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

2011-02-15

28

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

29

Mechanism of Selective Oxidation and Ammoxidation of Propene on Bismuth Molybdates from DFT Calculations on Model Clusters  

E-print Network

Mechanism of Selective Oxidation and Ammoxidation of Propene on Bismuth Molybdates from DFT catalysts for these reactions is based on bismuth molybdate.2-4 The mechanism has been proposed as follows:5,6 (1) Allylic H abstraction at a bismuth site resulting in an allyl intermediate adsorbing

Goddard III, William A.

30

Growth of silicon bump induced by swift heavy ion at the silicon oxide-silicon interface  

SciTech Connect

Thin silicon oxide layers on silicon substrates are investigated by scanning probe microscopy before and after irradiation with 210 MeV Au+ ions. After irradiation and complete chemical etching of the silicon oxide layer, silicon bumps grown on the silicon surface are observed. It is shown that each impinging ion induces one silicon bump at the interface. This observation is consistent with the thermal spike theory. Ion energy loss is transferred to the oxide and induces local melting. Silicon-bump formation is favored when the oxide and oxide-silicon interface are silicon rich.

Carlotti, J.-F.; Touboul, A.D.; Ramonda, M.; Caussanel, M.; Guasch, C.; Bonnet, J.; Gasiot, J. [CEM2, UMR-CNRS 5507, cc083, Universite de Montpellier 2, 34095 Montpellier cedex 5 (France); LMCP, cc082, Universite de Montpellier 2, 34095 Montpellier cedex 5 (France); Electrical Engineering and Computer Science Department, Vanderbuilt University, Sta. B, Box 351608, Nashville, Tennessee 37235-1608 (United States); LAIN, UMR 5011-CNRS, cc082, Universite de Montpellier 2, 34095 Montpellier cedex 5 (France); CEM2, UMR-CNRS 5507, cc083, Universite de Montpellier 2, 34095 Montpellier cedex 5 (France)

2006-01-23

31

Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.  

PubMed

A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2?% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell. PMID:25138735

Han, Lihao; Abdi, Fatwa F; van de Krol, Roel; Liu, Rui; Huang, Zhuangqun; Lewerenz, Hans-Joachim; Dam, Bernard; Zeman, Miro; Smets, Arno H M

2014-10-01

32

Oxidation mechanism of formic Acid on the bismuth adatom-modified pt(111) surface.  

PubMed

In order to improve catalytic processes, elucidation of reaction mechanisms is essential. Here, supported by a combination of experimental and computational results, the oxidation mechanism of formic acid on Pt(111) electrodes modified by the incorporation of bismuth adatoms is revealed. In the proposed model, formic acid is first physisorbed on bismuth and then deprotonated and chemisorbed in formate form, also on bismuth, from which configuration the C-H bond is cleaved, on a neighbor Pt site, yielding CO2. It was found computationally that the activation energy for the C-H bond cleavage step is negligible, which was also verified experimentally. PMID:25188779

Perales-Rondón, Juan Victor; Ferre-Vilaplana, Adolfo; Feliu, Juan M; Herrero, Enrique

2014-09-24

33

Bismuth Oxide: A New Lithium-Ion Battery Anode  

PubMed Central

Bismuth oxide directly grown on nickel foam (p-Bi2O3/Ni) was prepared by a facile polymer-assisted solution approach and was used directly as a lithium-ion battery anode for the first time. The Bi2O3 particles were covered with thin carbon layers, forming network-like sheets on the surface of the Ni foam. The binder-free p-Bi2O3/Ni shows superior electrochemical properties with a capacity of 668 mAh/g at a current density of 800 mA/g, which is much higher than that of commercial Bi2O3 powder (c-Bi2O3) and Bi2O3 powder prepared by the polymer-assisted solution method (p-Bi2O3). The good performance of p-Bi2O3/Ni can be attributed to higher volumetric utilization efficiency, better connection of active materials to the current collector, and shorter lithium ion diffusion path. PMID:24416506

Li, Yuling; Trujillo, Matthias A.; Fu, Engang; Patterson, Brian; Fei, Ling; Xu, Yun; Deng, Shuguang; Smirnov, Sergei; Luo, Hongmei

2013-01-01

34

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

35

Silicon membrane nanofilters from sacrificial oxide removal  

Microsoft Academic Search

Silicon micropore filter designs using a sacrificial oxide removal technique are described. These filters utilize surface and bulk micromachining for precise control of pore sizes in the tens of nanometers range. The semipermeable membrane of the sacrificial layer filters (SLFs) is typically composed of sandwiched p+ polysilicon\\/oxide\\/p+ silicon layers where the sacrificial oxide between the two silicon layers determines the

Wen-Hwa Chu; Ruby Chin; Tony Huen; Mauro Ferrari

1999-01-01

36

Memory switching in films of oxide glasses containing bismuth  

Microsoft Academic Search

Negative resistance and memory switching effects have been observed in Na2O-B2O3-Bi2O3-SiO2 glass films of thicknesses between 2 and 14 mu m. The off-state resistance could possibly arise due to electron hopping between conducting islands of bismuth. The on-state characteristics suggest that the memory action might be due to the formation of metallic filaments between the bismuth particles.

D. Chakravorty; C. S. Murthy

1975-01-01

37

Ultrafast nonlinear optical responses of bismuth doped silicon-rich silica films  

NASA Astrophysics Data System (ADS)

Nonlinear optical responses of bismuth (Bi) doped silicon-rich silicon dioxide (Si-rich SiO2) films were studied by a z-scan and an optical Kerr gate method under femtosecond excitation around 800 nm. It was found that the Bi-doping enhances the nonlinear optical response of Si-rich SiO2 films by several orders of magnitudes. The nonlinear refractive index was of the order of 10-11 cm2/W and the response time was shorter than our time resolution of 100 fs. The nonlinear refractive index was independent of the wavelength in the range from 750 to 835 nm, suggesting that virtual transitions are involved in the nonlinear optical processes.

Imakita, Kenji; Tsuchihashi, Yuya; Naruiwa, Ryo; Fujii, Minoru; Sun, Hong-Tao; Qiu, Jianrong; Hayashi, Shinji

2012-11-01

38

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

39

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

SciTech Connect

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

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

1980-03-01

40

Observation of Collective Strong Coupling between a Superconducting Resonator and Bismuth Dopants in Silicon  

NASA Astrophysics Data System (ADS)

All electrical readout and control of spin systems with superconducting circuitry is an attractive route for implementing hybrid quantum information processing. Isolated spins, in general, have much longer coherence times than present day superconducting qubits, and thus could be utilized as memory elements. Species with a zero-field splitting (ZFS), such as bismuth doped silicon or NV centers in diamond, are particularly attractive as the absence of a strong magnetic bias field facilitates compatibility with low loss superconducting circuitry. We present results on the interaction of a tunable superconducting resonator and an ensemble of Bi spins implanted in an epitaxial layer of 28Si. As the resonator tunes through the ZFS, we observe an avoided crossing indicative of collective strong coupling. We discuss coherence properties as a function of spin density as well as progress on the detection of a small number of spins using a dispersive nanoSQUID magnetometer.

Antler, Natania; Vijay, R.; Weis, Christoph; Levenson-Falk, Eli; Schenkel, Thomas; Siddiqi, Irfan

2011-03-01

41

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

SciTech Connect

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

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

2011-12-31

42

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

SciTech Connect

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

Du, W.; Su, D.; Wang, Q.; Frenkel, A.I.; Teng, X.

2011-01-11

43

Ion-exchange chromatographic separation of anions on hydrated bismuth oxide impregnated papers  

SciTech Connect

A comparative study of the chromatographic behavior of anions, iodide, sulfide, phosphate, arsenate, arsenite, vanadate, chromate, dichromate, thiosulfate, thiocyanate, ferricyanide and ferrocyanide on papers impregnated with hydrated bismuth oxide and untreated Whatman no.1 paper has been made by employing identical aqueous, non-aqueous and mixed solvent system. Sharp and compact spots were obtained with impregnated papers whereas the opposite applied to plain papers. Various analytically important binary and ternary separations are reported.

Dabral, S.K.; Muktawat, K.P.S.; Rawat, J.P.

1988-04-01

44

A Ferroelectric Oxide Made Directly on Silicon  

SciTech Connect

Metal oxide semiconductor field-effect transistors, formed using silicon dioxide and silicon, have undergone four decades of staggering technological advancement. With fundamental limits to this technology close at hand, alternatives to silicon dioxide are being pursued to enable new functionality and device architectures. We achieved ferroelectric functionality in intimate contact with silicon by growing coherently strained strontium titanate (SrTiO{sub 3}) films via oxide molecular beam epitaxy in direct contact with silicon, with no interfacial silicon dioxide. We observed ferroelectricity in these ultrathin SrTiO{sub 3} layers by means of piezoresponse force microscopy. Stable ferroelectric nanodomains created in SrTiO{sub 3} were observed at temperatures as high as 400 kelvin.

Warusawithana, M.; Cen, C; Sleasman, C; Woicik, J; Li, Y; Fitting Kourkoutis, L; Klug, J; Li, H; Ryan, P; et. al.

2009-01-01

45

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

46

Silicon oxide colloidal/polymer nanocomposite films Haifeng Wanga)  

E-print Network

Silicon oxide colloidal/polymer nanocomposite films Haifeng Wanga) and Wenwu Cao Materials Research 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

Cao, Wenwu

47

Heat-reflecting windows using gold and bismuth oxide films  

Microsoft Academic Search

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

L. Holland; G. Siddall

1958-01-01

48

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

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

2014-07-23

49

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

50

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

E-print Network

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

Lee, Jong Duk

51

Incorporation of thiosemicarbazide in Amberlite IRC-50 for separation of astatine from alpha-irradiated bismuth oxide.  

PubMed

A chelating resin was synthesized by incorporating thiosemicarbazide into Amberlite IRC-50, a weakly acidic polymer. Astatine radionuclides produced by alpha-irradiating bismuth oxide were separated using the newly synthesized chelating resin. The resin showed high selectivity for astatine. The adsorbed astatine was recovered using 0.1M EDTA at pH approximately 10. PMID:15110342

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

2004-06-01

52

Characterization of oxide layers grown on D9 austenitic stainless steel in lead bismuth eutectic  

NASA Astrophysics Data System (ADS)

Lead bismuth eutectic (LBE) is a possible coolant for fast reactors and targets in spallation neutron sources. Its low melting point, high evaporation point, good thermal conductivity, low reactivity, and good neutron yield make it a safe and high performance coolant in radiation environments. The disadvantage is that it is a corrosive medium for most steels and container materials. This study was performed to evaluate the corrosion behavior of the austenitic stainless steel D9 in oxygen controlled LBE. In order to predict the corrosion behavior of steel in this environment detailed analyses have to be performed on the oxide layers formed on these materials and various other relevant materials upon exposure to LBE. In this study the corrosion/oxidation of D9 stainless steel in LBE was investigated in great detail. The oxide layers formed were characterized using atomic force microscopy, magnetic force microscopy, nanoindentation, and scanning electron microscopy with wavelength-dispersive spectroscopy (WDS) to understand the corrosion and oxidation mechanisms of D9 stainless steel in contact with the LBE. What was previously believed to be a simple double oxide layer was identified here to consist of at least 4 different oxide layers. It was found that the inner most oxide layer takes over the grain structure of what used to be the bulk steel material while the outer oxide layer consists of freshly grown oxides with a columnar structure. These results lead to a descriptive model of how these oxide layers grow on this steel under the harsh environments encountered in these applications.

Hosemann, P.; Hawley, M.; Koury, D.; Swadener, J. G.; Welch, J.; Johnson, A. L.; Mori, G.; Li, N.

2008-04-01

53

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

54

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

55

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

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)

2002-01-01

56

Oxidative Deprotection Of Trimethylsilyl and Tetrahydropyranyl Ethers and Ethylene Acetals With Benzyltriphenylphosphonium Peroxomonosulfate in the Presence of Bismuth Chloride Under NonAqueous Conditions  

Microsoft Academic Search

Benzyltriphenylphosphonium peroxomonosulfate (BnPh3PHSO5 ) (1) is used as a new reagent for oxidative deprotection of trimethylsilyl and tetrahydropyranyl ethers and ethylene acetals to afford carbonyl compounds in refluxing acetonitrile in the presence of bismuth chloride.

A. R. Hajipour; S. E. Mallakpour; I. Mohammadpoor-baltork; H. Adibi

2000-01-01

57

Pattern-induced ripple structures at silicon-oxide\\/silicon interface by excimer laser irradiation  

Microsoft Academic Search

Ripple structures by KrF excimer laser irradiation have been observed on a silicon surface capped with a thin layer of patterned silicon oxide. The ripples are highly dependent on the patterns of the silicon oxide. They are centered and enhanced at the boundaries of the opened windows, forming a radial-wavelike structure. The formation of the ripples is attributed to the

X. Y. Chen; Y. F. Lu; B. J. Cho; Y. P. Zeng; J. N. Zeng; Y. H. Wu

2002-01-01

58

Iron-oxide catalyzed silicon photoanode for water splitting  

E-print Network

This thesis presents an integrated study of high efficiency photoanodes for water splitting using silicon and iron-oxide. The fundamental limitations of silicon to water splitting applications were overcome by an ultrathin ...

Jun, Kimin

2011-01-01

59

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

PubMed

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. PMID:24991508

Tucher, Johannes; Streb, Carsten

2014-01-01

60

Fabrication and testing of oxidized porous silicon field emitter strips  

E-print Network

) Vasanta Bhanu Madduri, B. E. , Osmania University Chair of Advisory Committee: Dr. Mark H. Weichold Field emitting cathode structures using a new material, oxidized porous silicon, are fabricated and characterized. The emission occurs from micro...-tips formed at the interface between the oxidized porous silicon and the bulk silicon. The density of the emission tips is proportional to the pore density. Porous silicon cathode strips are formed by anodic dissolution of photolithographically patterned p...

Madduri, Vasanta Bhanu

2012-06-07

61

Oxidation of silicon containing steel E. J. Song1  

E-print Network

Oxidation of silicon containing steel E. J. Song1 , D. W. Suh*1 and H. K. D. H. Bhadeshia1,2 Steels containing sufficient concentrations of silicon tend to form a low melting temperature oxide called fayalite, which then penetrates both the steel and any other oxide to form a mechanical key. As a consequence

Cambridge, University of

62

Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement  

PubMed Central

Objectives To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05). Results The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05). Conclusions The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated. PMID:25141197

MARCIANO, Marina Angelica; GARCIA, Roberto Brandao; CAVENAGO, Bruno Cavalini; MINOTTI, Paloma Gagliardi; MIDENA, Raquel Zanin; GUIMARAES, Bruno Martini; ORDINOLA-ZAPATA, Ronald; DUARTE, Marco Antonio Hungaro

2014-01-01

63

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

E-print Network

Silicon Oxide Etch Process To remove the areas of silicon dioxide unprotected by photoresist be started within 30 minutes of the completion of the hard bake of the photoresist. 2. Use Buffered Oxide for two minutes in running DI water. 8.2 Dry the wafer with an N2 gun. 8.3 Check the color of the oxide

Kim, Philip

64

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

65

Guided photoluminescence study of Nd-doped silicon rich silicon oxide and silicon rich silicon nitride waveguides  

NASA Astrophysics Data System (ADS)

Planar waveguides made of Nd3+-doped silicon rich silicon oxide (SRSO) and silicon rich silicon nitride (SRSN) have been fabricated by reactive magnetron sputtering and characterized with special emphasis on the comparison of the guided photoluminescence (PL) properties of these two matrices. Guided fluorescence excited by top surface pumping at 488 nm on planar waveguides was measured as a function of the distance between the excitation area and the output of the waveguide, as well as a function of the pump power density. The PL intensity increased linearly with pump power without any saturation even at high power. The linear intensity increase of the Nd3+ guided PL under a non-resonant excitation (488 nm) confirms the efficient coupling between either Si-np and rare-earth ions for SRSO or radiative defects and rare earth ions for SRSN. The guided fluorescences at 945 and 1100 nm were observed until 4 mm and 8 mm of the output of the waveguide for Nd3+ doped SRSO and SRSN waveguides, respectively. The guided fluorescence decays of Nd3+-doped-SRSO and -SRSN planar waveguides have been measured and found equal to 97 ?s ±7 and 5 ?s ± 2, respectively. These results show notably that the Nd3+-doped silicon rich silicon oxide is a very promising candidate on the way to achieve a laser cavity at 1.06 ?m.

Pirasteh, Parastesh; Charrier, Joël; Dumeige, Yannick; Doualan, Jean-Louis; Camy, Patrice; Debieu, Olivier; Liang, Chuan-hui; Khomenkova, Larysa; Lemaitre, Jonathan; Boucher, Yann G.; Gourbilleau, Fabrice

2013-07-01

66

Silicon surfaces : metallic character, oxidation and adhesion A. Cros (*)  

E-print Network

707 Silicon surfaces : metallic character, oxidation and adhesion A. Cros (*) IBM T.J. Watson on the growth mode ofmetal atoms and the oxidation ofthe silicon surface atoms. These phenomena are discussed long range order or not has a great importance. There are at least two cases where basic properties

Paris-Sud XI, Université de

67

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

68

Nitric oxide-releasing porous silicon nanoparticles  

PubMed Central

In this study, the ability of porous silicon nanoparticles (PSi NPs) to entrap and deliver nitric oxide (NO) as an effective antibacterial agent is tested against different Gram-positive and Gram-negative bacteria. NO was entrapped inside PSi NPs functionalized by means of the thermal hydrocarbonization (THC) process. Subsequent reduction of nitrite in the presence of d-glucose led to the production of large NO payloads without reducing the biocompatibility of the PSi NPs with mammalian cells. The resulting PSi NPs demonstrated sustained release of NO and showed remarkable antibacterial efficiency and anti-biofilm-forming properties. These results will set the stage to develop antimicrobial nanoparticle formulations for applications in chronic wound treatment. PMID:25114633

2014-01-01

69

Characterization of thin silicon oxide obtained by lamp heating  

Microsoft Academic Search

Ultrathin gate oxides (90–300 Å) have been grown on silicon under dry oxygen using a lamp light heater. The oxidation kinetics is quite different from that expected in conventional furnace oxidation since the process is shown to be diffusion limited.

A. Slaoui; J. P. Ponpon; P. Siffert

1987-01-01

70

A new nano bismuth(III) salophen catalyst for green and efficient catalytic oxidation of sulfides into the corresponding sulfoxides  

NASA Astrophysics Data System (ADS)

Bismuth(III) salophen as a new catalyst has been synthesized. Structural properties of this complex have been studied by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and thermal gravimetric analyses. The average crystalline size of Bi-salophen particles was 86 nm. Thermal analyses show that the complex is stable over 300°C. Catalytic activity of this catalyst has been investigated in oxidation of sulfides. Different kinds of sulfides have been oxidized to the corresponding sulfoxides efficiently in the presence of sodium periodate as oxidant in glacial acetic acid as solvent at room temperature. These sulfides were selectively and completely converted into their corresponding sulfoxides in very short reaction times. Selectivity of this method was excellent, which is another advantage of this method.

Tajgardoon, Mohammad Ghaem; Jafari, Marzieh; Rafiee, Ezzat; Feyzi, Mostafa; Joshaghani, Mohammad

2012-06-01

71

Growth of silicon quantum dots by oxidation of the silicon nanocrystals embedded within silicon carbide matrix  

NASA Astrophysics Data System (ADS)

A moderately low temperature (?800 °C) thermal processing technique has been described for the growth of the silicon quantum dots (Si-QD) within microcrystalline silicon carbide (?c-SiC:H) dielectric thin films deposited by plasma enhanced chemical vapour deposition (PECVD) process. The nanocrystalline silicon grains (nc-Si) present in the as deposited films were initially enhanced by aluminium induced crystallization (AIC) method in vacuum at a temperature of Tv = 525 °C. The samples were then stepwise annealed at different temperatures Ta in air ambient. Analysis of the films by FTIR and XPS reveal a rearrangement of the ?c-SiC:H network has taken place with a significant surface oxidation of the nc-Si domains upon annealing in air. The nc-Si grain size (DXRD) as calculated from the XRD peak widths using Scherrer formula was found to decrease from 7 nm to 4 nm with increase in Ta from 250 °C to 800 °C. A core shell like structure with the nc-Si as the core and the surface oxide layer as the shell can clearly describe the situation. The results indicate that with the increase of the annealing temperature in air the oxide shell layer becomes thicker and the nc-Si cores become smaller until their size reduced to the order of the Si-QDs. Quantum confinement effect due to the SiO covered nc-Si grains of size about 4 nm resulted in a photoluminescence peak due to the Si QDs with peak energy at 1.8 eV.

Kole, Arindam; Chaudhuri, Partha

2014-10-01

72

Porous silicon oxide anti-reflection coating for solar cells  

Microsoft Academic Search

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

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

1982-01-01

73

Silicon Oxide Etch Process This process removes silicon dioxide (SiO2) which will expose the silicon underneath; it  

E-print Network

the silicon underneath; it removes the areas of silicon dioxide unprotected by photoresist. Preparation of the hard bake of the photoresist. 1) Use Buffered Oxide Etch (BOE) solution [6 parts 40% NH4F and 1 part 49 is hydrophilic. If you find there is still color to the surface and there is still wetting or sheeting of DI

Kim, Philip

74

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

75

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

NASA Astrophysics Data System (ADS)

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

Agarwal, Khushboo; Mehta, B. R.

2014-08-01

76

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

NASA Astrophysics Data System (ADS)

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

Gannon, John J., Jr.

77

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

78

Supported bismuth oxide catalysts for the selective reduction of NO with propene in lean conditions  

Microsoft Academic Search

Bi2O3\\/Al2O3 materials were prepared by impregnation of a ?-Al2O3 support with bismuth citrate and tested as catalysts for the selective catalytic reduction of NO with propene. Under simulated diesel exhaust gas conditions (500ppm NO, 10% O2, 6% H2O) with 600ppm propene as reductant, a maximum in NO conversion of 56% was attained at 525°C and a GHSV of ca. 30,000h?1.

Dennis E. Sparks; Patricia M. Patterson; Gary Jacobs; Mark Crocker; John A. Chaney

2006-01-01

79

Growth control of tungsten oxide nanostructures on planar silicon substrates  

Microsoft Academic Search

Tungsten oxide nanostructures were deposited on silicon substrates by a thermal oxidation approach. The major factors influencing their phase structure and growth morphology were found to be the substrate temperature and the chamber pressure. By investigating the growth process of these nanostructures, a phase growth diagram was constructed, with which one can realize the phase selection and morphology control of

Floriane Galléa; Zhengcao Li; Zhengjun Zhang

2006-01-01

80

Development of an electrochemically reduced graphene oxide modified disposable bismuth film electrode and its application for stripping analysis of heavy metals in milk.  

PubMed

A novel electrochemical sensing platform based on electrochemically reduced graphene oxide film modified screen-printed electrode was developed. This disposable electrode shows excellent conductivity and fast electron transfer kinetics. By in situ plating bismuth film, the developed electrode exhibited well-defined and separate stripping peaks for cadmium and lead. Several parameters, including electrolytes environment and electrodeposition conditions, were carefully optimized to achieve best stripping performance. The linear range for both metal ions at the disposable bismuth film electrode was from 1.0 ?g L(-1) to 60.0 ?g L(-1). The detection limit was 0.5 ?g L(-1) for cadmium ion and 0.8 ?g L(-1) for lead ion. Milk sample analysis demonstrates that the developed electrode could be effectively used to detect low levels (?g L(-1)) of cadmium ion and lead ion. Graphene based disposable bismuth film electrode is a sensitive, stable, and reliable sensing platform for heavy metals determination. PMID:24423503

Ping, Jianfeng; Wang, Yixian; Wu, Jian; Ying, Yibin

2014-05-15

81

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

SciTech Connect

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

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

1993-08-01

82

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

83

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

84

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

PubMed

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

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

2014-12-18

85

Zinc oxide varistors and/or resistors  

DOEpatents

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

86

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

87

Oxygen permeation in bismuth-based materials part I: Sintering and oxygen permeation fluxes  

E-print Network

1 Oxygen permeation in bismuth-based materials part I: Sintering and oxygen permeation fluxes E;2 Abstract Oxygen permeation measurements were performed on two layered bismuth based oxide ceramics, 81.05M, 84.32F Keywords: bismuth erbium oxide, bismuth calcium oxide, BIMEVOX, oxygen permeation #12

Paris-Sud XI, Université de

88

Samarium- and ytterbium-promoted oxidation of silicon and gallium arsenide surfaces  

SciTech Connect

A method is described for promoting oxidation of a silicon or gallium arsenide surface comprising: depositing a ytterbium overlayer on the silicon or gallium arsenide surface prior to the oxidation of the surface.

Franciosi, A.

1989-02-21

89

Photo-oxidation of hydrogen passivated silicon surfaces  

NASA Astrophysics Data System (ADS)

Conventional and synchrotron photoelectron spectroscopy and a custom experimental setup are used to investigate how factors present in cleanrooms, including UV light, O2, and H2O, lead to contamination of the hydrogen passivated surface. Experimental results indicate that both the H-Si(111) and the Hx-Si(100) surfaces oxidize when exposed to UV light in the presence of O2 only, H2O only, or both O2 and H2O. We propose that UV light assists in the photo-oxidation of hydrogen terminated silicon surfaces by cleaving the H-Si bond. This process generates silicon surface radicals that can then be scavenged by either O2 to form Si-O-O· or by H2O to form Si-OH. Results also show that oxide contamination is most significant when the surface is exposed to both O2 and H2O (humid air) in the presence of UV light. In this humid air case, the water molecule is expected to more readily react with silicon surface radicals than the oxygen molecule. Polarization of the surface by the Si-OH bonding is thought to weaken the Si-Si backbond and make incorporation of oxygen, by O2, more energetically favorable. UV light also assist the oxidation process by providing the energy required for a successful electron transfer between the substrate and the O2 molecule. This electron transfer process creates reactive O2- species. This dissertation also shows that the extent of silicon surface photo-oxidation depends on the surface preparation condition which is determined by the concentration of HF used to hydrogen passivate the surface. Results show that the 250:1HF solution does not as effectively hydrogen passivate the Si(100) surface as does the 50:1HF solution. Comparison of the SR-PES Si(2p) spectra indicates that the 250:1HF prepared surface has a lower density of hydrides than the 50:1HF prepared surface. The study of how surface microstructure is affected by silicon processing conditions, obtained through XPS and SR-PES analysis, provides crucial information to the research community and to the silicon industry whose success depends on controlling the state of the silicon surface. Contrary to common understanding, the silicon surface can be kept oxidation-free for an extended period of time. Therefore, the need to clean silicon at the point-of-use has been eliminated.

Morse, Kathleen Anne

90

Nanostructured bismuth vanadate-based materials for solar-energy-driven water oxidation: a review on recent progress.  

PubMed

Water oxidation is the key step for both photocatalytic water splitting and CO2 reduction, but its efficiency is very low compared with the photocatalytic reduction of water. Bismuth vanadate (BiVO4) is the most promising photocatalyst for water oxidation and has become a hot topic for current research. However, the efficiency achieved with this material to date is far away from the theoretical solar-to-hydrogen conversion efficiency, mainly due to the poor photo-induced electron transportation and the slow kinetics of oxygen evolution. Fortunately, great breakthroughs have been made in the past five years in both improving the efficiency and understanding the related mechanism. This review is aimed at summarizing the recent experimental and computational breakthroughs in single crystals modified by element doping, facet engineering, and morphology control, as well as macro/mesoporous structure construction, and composites fabricated by homo/hetero-junction construction and co-catalyst loading. We aim to provide guidelines for the rational design and fabrication of highly efficient BiVO4-based materials for water oxidation. PMID:25325232

Huang, Zhen-Feng; Pan, Lun; Zou, Ji-Jun; Zhang, Xiangwen; Wang, Li

2014-11-01

91

Active oxidation: Silicon etching and oxide decomposition basic mechanisms using density functional theory  

Microsoft Academic Search

The etching of silicon atom from the Si(100)-p(2×2) surface, i.e. the desorption of SiO molecules from this surface, either clean or pre-oxidized, is investigated at the density functional theory level. The reaction paths for desorption are given as a function of the initial oxidation state of the extracted silicon atom. The associated activation energies and the atomic configurations are discussed.

A. Hemeryck; N. Richard; A. Estève; M. Djafari Rouhani

2007-01-01

92

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

SciTech Connect

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

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

2012-01-09

93

Correlation of gate oxide integrity with crystalline defects in silicon  

Microsoft Academic Search

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

Masaro Tamatsuka

1997-01-01

94

Effects of silicone pretreatment on oxidative hair damage  

Microsoft Academic Search

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

MARIANNE D. BERTHIAUME; JAMES H. MERRIFIELD

95

One dimensional silicon nanostructures prepared by oxidized porous silicon under heat treatment  

NASA Astrophysics Data System (ADS)

One dimensional high aspect ratio Si nanostructures were prepared by using oxidized sponge like nanostructured porous silicon (pSi) as a seed material. This can be considered as a complementary technique to synthesize silicon nanowires such as vapour-liquid-solid method (VLS). One dimensional silicon nanostructures were fabricated by subjecting pSi to heat treatment without metal assistance. It is shown that the aspect ratio can be tuned by controlling the concentration of oxygen (SiO2) and the porosity of the seed material (pSi). The atomic percentage of oxygen incorporated into pSi was estimated by Energy Dispersive X-ray Spectroscopy (EDS). Field Emission Scanning Electron Microscope (FESEM) confirms unambiguously the formation of silicon nanowires. The broad peak observed around 490 cm-1 in Raman spectra further confirms the formation of Si NWs. At higher oxygen concentration, narrower (?20 nm) and longer (?1 ?m) silicon nanowires have been achieved. The observed change in photoluminescence (PL) peak position towards lower wavelength as a function of the aspect ratio of Si NWs is in good agreement with quantum confinement effects. This work demonstrates a new oxide assisted method to prepare high aspect ratio silicon nanowires without using any metal catalysts.

Vendamani, V. S.; Pathak, A. P.; Rao, S. V. S. Nageswara

2014-11-01

96

Properties of Silicon and Metal Oxide Electrowetting Systems  

Microsoft Academic Search

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

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

2012-01-01

97

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

98

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

99

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

Microsoft Academic Search

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

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

2006-01-01

100

UNCORRECTEDPROOF 2 Optical properties of bismuth borate glasses  

E-print Network

UNCORRECTEDPROOF 2 Optical properties of bismuth borate glasses 3 Isabella-Ioana Oprea, Hartmut.70.Ce; 78.20.Ci 13 Keywords: Bismuth borate; Glass; Refractive index; Optical properties 14 1 environment, i.e., in glass. Combining 34 bismuth oxide with boric oxide thus allows to tune the 35 optical

Osnabrück, Universität

101

Tribological interaction between polytetrafluoroethylene and silicon oxide surfaces.  

PubMed

We investigated the tribological interaction between polytetrafluoroethylene (PTFE) and silicon oxide surfaces. A simple rig was designed to bring about a friction between the surfaces via sliding a piece of PTFE on a thermally oxidized silicon wafer specimen. A very mild inclination (?0.5°) along the sliding motion was also employed in order to monitor the tribological interaction in a gradual manner as a function of increasing contact force. Additionally, some patterns were sketched on the silicon oxide surface using the PTFE tip to investigate changes produced in the hydrophobicity of the surface, where the approximate water contact angle was 45° before the transfer. The nature of the transferred materials was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XPS results revealed that PTFE was faithfully transferred onto the silicon oxide surface upon even at the slightest contact and SEM images demonstrated that stable morphological changes could be imparted onto the surface. The minimum apparent contact pressure to realize the PTFE transfer is estimated as 5 kPa, much lower than reported previously. Stability of the patterns imparted towards many chemical washing processes lead us to postulate that the interaction is most likely to be chemical. Contact angle measurements, which were carried out to characterize and monitor the hydrophobicity of the silicon oxide surface, showed that upon PTFE transfer the hydrophobicity of the SiO2 surface could be significantly enhanced, which might also depend upon the pattern sketched onto the surface. Contact angle values above 100° were obtained. PMID:25362327

Uçar, A; Copuro?lu, M; Baykara, M Z; Ar?kan, O; Suzer, S

2014-10-28

102

Tribological interaction between polytetrafluoroethylene and silicon oxide surfaces  

NASA Astrophysics Data System (ADS)

We investigated the tribological interaction between polytetrafluoroethylene (PTFE) and silicon oxide surfaces. A simple rig was designed to bring about a friction between the surfaces via sliding a piece of PTFE on a thermally oxidized silicon wafer specimen. A very mild inclination (˜0.5°) along the sliding motion was also employed in order to monitor the tribological interaction in a gradual manner as a function of increasing contact force. Additionally, some patterns were sketched on the silicon oxide surface using the PTFE tip to investigate changes produced in the hydrophobicity of the surface, where the approximate water contact angle was 45° before the transfer. The nature of the transferred materials was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XPS results revealed that PTFE was faithfully transferred onto the silicon oxide surface upon even at the slightest contact and SEM images demonstrated that stable morphological changes could be imparted onto the surface. The minimum apparent contact pressure to realize the PTFE transfer is estimated as 5 kPa, much lower than reported previously. Stability of the patterns imparted towards many chemical washing processes lead us to postulate that the interaction is most likely to be chemical. Contact angle measurements, which were carried out to characterize and monitor the hydrophobicity of the silicon oxide surface, showed that upon PTFE transfer the hydrophobicity of the SiO2 surface could be significantly enhanced, which might also depend upon the pattern sketched onto the surface. Contact angle values above 100° were obtained.

Uçar, A.; ?opuro?lu, M.; Baykara, M. Z.; Ar?kan, O.; Suzer, S.

2014-10-01

103

Silicon nanowire circuits fabricated by AFM oxidation nanolithography.  

PubMed

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

Martínez, Ramses V; Martínez, Javier; Garcia, Ricardo

2010-06-18

104

Single layer of silicon quantum dots in silicon oxide matrix: Investigation of forming gas hydrogenation on photoluminescence properties and study of the composition of silicon rich oxide layers  

NASA Astrophysics Data System (ADS)

Structures consisting of a single layer of silicon quantum dots in a SiO 2 matrix show interesting optoelectronic properties and potential use as energy selective filters, which are a crucial component for the realization of the hot carrier solar cell. In this work single layer silicon quantum dots in SiO 2 have been realized using a magnetron sputtering technique. Quantum dots are formed by annealing of a silicon rich oxide layer deposited between a thermally grown SiO 2 layer and a sputtered SiO 2 layer. The effects of a forming gas post-hydrogenation process on the photoluminescence of the single layer of quantum dots have been investigated in order to understand the photoluminescence mechanism. It was found that for sputtered silicon quantum dots in SiO 2 matrix the photoemission mechanisms are primarily due to quantum confinement and does not strongly rely on matrix defects. In addition, physical and optical properties of several thick silicon rich oxide layers, with different chemical compositions, have been investigated in order to optimize the stoichiometry of silicon rich oxide in the single layers.

Aliberti, P.; Shrestha, S. K.; Li, Ruoyu; Green, M. A.; Conibeer, G. J.

2011-07-01

105

An oxide/silicon core/shell nanowire metal-oxide semiconductor field-effect transistor  

NASA Astrophysics Data System (ADS)

This paper studies an oxide/silicon core/shell nanowire MOSFET (OS-CSNM). Through three-dimensional device simulations, we have demonstrated that the OS-CSNM has a lower leakage current and higher Ion/Ioff ratio after introducing the oxide core into a traditional nanowire MOSFET (TNM). The oxide/silicon OS-CSNM structure suppresses threshold voltage roll-off, drain induced barrier lowering and subthreshold swing degradation. Smaller intrinsic device delay is also observed in OS-CSNM in comparison with that of TNM.

Zhang, Li-Ning; He, Jin; Zhou, Wang; Chen, Lin; Xu, Yi-Wen

2010-04-01

106

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

107

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

E-print Network

APS/xxxxx Silicon dry oxidation kinetics at low temperature in the nanometric range: modeling of silicon dry oxidation are investigated theoretically and experimentally at low tem- perature of the oxidation process conditions, experiments allow the investigation of the growth kinetics of nanometric oxide

Paris-Sud XI, Université de

108

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

E-print Network

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

Dunham, Scott

109

Low-Temperature Oxidation of silicon nitride by water in supercritical condition  

Microsoft Academic Search

Oxidation tests carried out in supercritical water (400–500 °C) revealed a noticeable corrosion attack on the silicon nitride surface in spite of the low temperatures. Increasing water pressure generally caused an increase in the oxidation phenomena. Oxidation scale evolution depended strictly on the silicon nitride sintering process, sintering aids, porosity and impurities, which influenced oxidation kinetics and surface morphology. In

Edoardo Proverbio; Fabio Carassiti

1996-01-01

110

Q-switched fibre laser using 21 cm Bismuth-erbium doped fibre and graphene oxide as saturable absorber  

NASA Astrophysics Data System (ADS)

A compact, Q-switched fibre laser is proposed and demonstrated using a compact Bismuth-based erbium doped fibre (Bi-EDF) together with a Graphene Oxide (GO) Saturable Absorber (SA). The 21 cm long Bi-EDF has an erbium dopant concentration of 6300 ppm with absorption rates of about 83 and 133 dB/m at 1480 and 1530 nm. The SA is fabricated from graphene flakes dissolved in water, forming a GO film that is sandwiched between two FC/PC connectors. The Q-switched Bi-EDF laser has an Amplified Spontaneous Emission (ASE) spectrum of 120 nm, stretching from 1490 to 1610 nm and a Q-switching threshold power of about 65 mW. At the maximum pump power of 118 mW, the pulses are generated with an average output power and pulse energy of 0.11 mW and 4.3 nJ, with a repetition rate and pulse width of 27.2 kHz and 7.7 ?s. The output can be tuned over the amplified spontaneous emission spectrum with an average peak power of about -16.8 dBm, and observation under a radio frequency spectrum analyser shows a highly stable output at 21.8 kHz. The proposed Bi-EDF laser will have substantial uses in applications requiring short and stable pulses such as rangefinding and sensing.

Ahmad, Harith; Zulkifli, Ahmad Zarif; Kiat, Yap Yuen; Harun, Sulaiman Wadi

2014-01-01

111

Fabrication of Optical Waveguide using Silicon Oxynitride Prepared by Thermal Oxidation of Silicon Rich Silicon Nitride  

Microsoft Academic Search

This work reports a method for reducing hydrogen content in silicon oxynitride film for integrated optical applications. The silicon oxynitride (SiON) films were grown by plasma enhanced chemical vapor deposition (PECVD) with N2O, NH3and SiH4as precursor gases. Using higher flow rate of SiH4and NH3, Si-rich oxynitride films with high refractive index were obtained. Detailed ellipsometry and Fourier transform infrared (FTIR)

C. K. Wong; H. Wong; M. Chan; C. W. Kok; H. P. Chan

2005-01-01

112

Nitrogen incorporation in thin oxides by constant current N2O plasma anodization of silicon and N2 plasma nitridation of silicon oxides  

Microsoft Academic Search

A helical resonator plasma source was used to perform constant current N2O plasma anodization of silicon and N2 plasma nitridation of silicon oxides. The nitrogen bonding structure and distribution in the oxides were studied using angle resolved x-ray photoelectron spectroscopy. Nitrogen corresponding to a N–Si3 bonding structure was detected at the silicon side of the interface, the Si–SiO2 interfacial region,

Sita R. Kaluri; Dennis W. Hess

1996-01-01

113

Effect of bismuth nanolayers on the oriented growth of fullerene C 60 on an amorphous substrate  

Microsoft Academic Search

The effect of a bismuth sublayer with an effective thickness of 0.5 to 4 nm on the structure of C60 fullerene films grown on amorphous substrates (silicon covered with a natural oxide layer; glass) using the quasi-closed-volume\\u000a method is studied. An x-ray diffraction study of fullerene films showed that the intensity ratio between the (220) and (111)\\u000a peaks depends nonmonotonically

V. E. Pukha; V. V. Varganov; I. F. Mikhailov; A. N. Drozdov

2004-01-01

114

Hydrogen passivation and ozone oxidation of silicon surface  

SciTech Connect

The oxidation of H/Si(100) and H/Si(111) with high concentration ozone gas was investigated with X-ray photoelectron spectroscopy (XPS). The ozone oxidation of partially hydride-covered surface was observed. The hydrogen termination reduced the rate of oxygen insertion into silicon backbond. The reduction of oxygen insertion rate by the H-termination for H/Si(100) was larger than that for H/Si(111). The dissociation rate of ozone molecule on H/Si was estimated to be {approx_equal}0.2 with a directional mass analyzer.

Kurokawa, Akira; Nakamura, Ken; Ichimura, Shingo [Electrotechnical Lab., Tsukuba (Japan)

1998-12-31

115

Optimization of Amorphous Silicon Oxide Buffer Layer for High-Efficiency p-Type Hydrogenated Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells  

NASA Astrophysics Data System (ADS)

Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) films deposited by very high frequency plasma-enhanced chemical vapor deposition (60 MHz VHF-PECVD) at a low substrate temperature of approximately 200 °C were used as a front buffer layer in p-type hydrogenated microcrystalline silicon oxide/n-type crystalline silicon (p-µc-SiO:H/n-c-Si) heterojunction solar cells. We found that the oxygen concentration in the i-a-SiO:H buffer layer strongly affected the solar cell performance and that the short wavelength response in quantum efficiency (QE) was improved by oxygen addition. Employing a p-µc-SiO:H/i-a-SiO:H/n-Si [Czochralski (CZ), 200 µm, (100)]/i-a-Si:H/n-a-Si:H/Ag/Al configuration, we achieved an efficiency of 17.9% with Voc of 671 mV.

Sritharathikhun, Jaran; Yamamoto, Hiroshi; Miyajima, Shinsuke; Yamada, Akira; Konagai, Makoto

2008-11-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

117

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

PubMed

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

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

2012-11-30

118

New perspectives on thermal and hyperthermal oxidation of silicon surfaces  

NASA Astrophysics Data System (ADS)

The growth of (ultra)thin silica (SiO2) layers on crystalline silicon (c-Si) and controlling the thickness of SiO2 is an important issue in the fabrication of microelectronics and photovoltaic devices (e.g., MOSFETs, solar cells, optical fibers etc.). Such ultrathin oxide can be grown and tuned even at low temperature (including room temperature), by hyperthermal oxidation or when performed on non-planar Si surfaces (e.g., Si nanowires or spheres). However, hyperthermal silica growth as well as small Si-NW oxidation in general and the initial stages in particular have not yet been investigated in full detail. This work is therefore devoted to controlling ultrathin silica thickness on planar and non-planar Si surfaces, which can open new perspectives in nanodevice fabrication. The simulation of hyperthermal (1-100 eV) Si oxidation demonstrate that at low impact energy (<10 eV), oxygen does not damage the Si surface and this energy region could thus beneficially be used for Si oxidation. In contrast to thermal oxidation, 10 eV species can directly oxidize Si subsurface layers. A transition temperature of about 700 K was found: below this temperature, the oxide thickness only depends on the impact energy of the impinging species. Above this temperature, the oxide thickness depends on the impact energy, type of oxidant and the surface temperature. The results show that control over the ultrathin oxide (a-SiO2) thickness is possible by hyperthermal oxidation of silicon surfaces at temperatures below the transition temperature. In small Si-NWs, oxidation is a self-limiting process that occurs at low temperature, resulting in small Si core - SiO2 shell (semiconductor + dielectric) or c-Si|SiOx| a-SiO2 nanowire, which has also being envisaged to be used as nanowire field-effect transistors and photovoltaic devices in near-future nanotechnology. Above the transition temperature such core-shell nanowires are completely converted to a-SiO2 nanowires. It can be concluded that an accurate control over the interfacial stress by choosing a suitable oxidation temperature and Si-NW diameter can lead to precise nanoscale control over the Si-core radius. All investigations were carried out by applying molecular dynamics calculations using the ReaxFF potential, allowing a accurately study of the underpinning physical and chemical processes.

Khalilov, Umedjon

119

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

120

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

E-print Network

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

Fossum, Eric R.

121

Photoluminescence from erbium incorporated in oxidized porous silicon  

NASA Astrophysics Data System (ADS)

In the present work, photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy were used to study oxidized porous silicon (OPS) doped with Er by electrochemical migration. Three types of OPS were investigated: (a) partially oxidized PS (POPS); (b) fully oxidized PS (FOPS); (c) oxidized PS co-doped with Fe (OPS:Fe). The OPS consists of oxide, Si nanoclusters and voids, and their composing fractions are dependent on the PS porosity and oxidation regime. The main result of this work is the assessment that the location of Er ions in composing fractions of OPS has a profound effect on the PL and PLE spectra. We show that for both POPS and FOPS, Er exhibits a broad 1530 nm PL spectrum similar to that observed in the Er-doped silica glasses. For POPS, the PLE spectrum of the 1530 nm Er PL band consists of a superposition of sharp peaks, which are attributed to the absorption transitions of Er ions incorporated into the oxide fraction, and a broad band, which is related to the absorption band of Si nanoclusters. For FOPS, the PLE spectrum consists just of sharp peaks. In contrast to POPS and FOPS, for OPS:Fe, Er PL spectrum consists of 21 highly resolved peaks. PLE spectrum of the strongest 1535 nm PL peak represents a wide band which is attributed to the absorption band of Fe:O nanoclusters formed inside OPS:Fe. Mechanism of excitation and luminescence of Er ions in OPS is presented.

Bondarenko, V.; Kazuchits, N.; Balucani, M.; Ferrari, A.

2005-02-01

122

Method for removing oxide contamination from silicon carbide powders  

DOEpatents

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

Brynestad, J.; Bamberger, C.E.

1984-08-01

123

Efficient photovoltaic heterojunctions of indium tin oxides on silicon  

NASA Technical Reports Server (NTRS)

Heterojunction diodes of indium tin oxide films sputtered on to p-silicon using ion-beam techniques display significant photovoltaic effects when exposed to sunlight. Galvanomagnetic and optical measurements confirm that the oxide films are highly degenerate transparent semiconductors. At a tin oxide concentration of 10%, an open-circuit voltage of 0.51 V was observed along with a short-circuit current of 32 mA/sq cm, a fill factor of 0.70, and a conversion efficiency of 12%. As the concentration was raised to 70%, the voltage remained steady, the current fell to 27 mA/sq cm, and the fill factor fell to 0.60

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

1976-01-01

124

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

125

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

Microsoft Academic Search

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

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

2011-01-01

126

Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor  

NASA Technical Reports Server (NTRS)

A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

2001-01-01

127

Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor  

NASA Technical Reports Server (NTRS)

A process for producing polycrystalline silicon carbide includes heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

2000-01-01

128

Method of fabricating conducting oxide-silicon solar cells utilizing electron beam sublimation and deposition of the oxide  

Microsoft Academic Search

In preparing tin oxide and indium tin oxide-silicon heterojunction solar cells by electron beam sublimation of the oxide and subsequent deposition thereof on the silicon, the engineering efficiency of the resultant cell is enhanced by depositing the oxide at a predetermined favorable angle of incidence. Typically the angle of incidence is between 40° and 70° and preferably between 55° and

T. Feng; A. K. Ghosh

1979-01-01

129

Method of fabricating conducting oxide-silicon solar cells utilizing electron beam sublimation and deposition of the oxide  

Microsoft Academic Search

In preparing tin oxide and indium tin oxide-silicon heterojunction solar cells by electron beam sublimation of the oxide and subsequent deposition thereof on the silicon, the engineering efficiency of the resultant cell is enhanced by depositing the oxide at a predetermined favorable angle of incidence. Typically the angle of incidence is between 40.degree. and 70.degree. and preferably between 55.degree. and

Tom Feng; Amal K. Ghosh

1979-01-01

130

The effect of bismuth on the selective oxidation of lactose on supported palladium catalysts.  

PubMed

The selective oxidation of lactose by molecular oxygen has been studied in a batch reactor containing an aqueous slurry of 0.5 kmol m-1 reactant and 1.0 kg m-3 catalyst. The in situ Bi promotion of a commercial Pd-C catalyst resulted in 100% selectivity to sodium lactobionate up to conversions of 95% in the pH range 7-10 and at temperatures up to 333 K. Performing the reaction under such conditions that the oxygen transfer to the liquid phase was rate-controlling allowed the production of sodium lactobionate in high yields in approximately 1 h. A maximum initial reaction-rate of 0.47 mol kg-1 s-1 was found at a molar Bi to Pd ratio of 0.50-0.67. Fifteen batches of lactose were oxidized with the same charge of catalyst without significant loss in initial activity or selectivity. Such other aldoses as maltose, glucose, and galactose could be oxidized analogously with similar selectivities. PMID:2279242

Hendriks, H E; Kuster, B F; Marin, G B

1990-09-01

131

Correlation of gate oxide integrity with crystalline defects in silicon  

NASA Astrophysics Data System (ADS)

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

Tamatsuka, Masaro

1997-12-01

132

Nonvolatile polycrystalline silicon thin-film-transistor memory with oxide/nitride/oxide stack gate dielectrics and nanowire channels  

NASA Astrophysics Data System (ADS)

In this work, the authors study a polycrystalline silicon thin-film transistor (poly-Si TFT) with oxide/nitride/oxide (ONO) stack gate dielectrics and multiple nanowire channels for the applications of both nonvolatile silicon-oxide-nitride-oxide-silicon (SONOS) memory and switch transistor. The proposed device named as nanowire SONOS-TFT has superior electrical characteristics of a transistor such as on/off current ratio, threshold voltage (Vth), and subthreshold slope due to the good gate control ability originated from fringing electrical field effects. Moreover, the proposed device under adequate operation scheme can exhibit high program/erase efficiency and good retention time characteristics at high temperature.

Chen, Shih-Ching; Chang, Ting-Chang; Liu, Po-Tsun; Wu, Yung-Chun; Yeh, Ping-Hung; Weng, Chi-Feng; Sze, S. M.; Chang, Chun-Yen; Lien, Chen-Hsin

2007-03-01

133

Physical and electrical properties of copper oxide doped bismuth borate glasses  

NASA Astrophysics Data System (ADS)

The role of CuO on the physical and electrical properties in x CuO.(25-x)Bi2O3.75B2O3;(5?x?20) glass system has been investigated. The glasses were prepared by normal melt quench technique. The density and molar volume of the glasses decreases with increase in CuO (mol %). The dc conductivity was measured in the temperature range 413-513 K. The conduction mechanism in these glasses was discussed in terms of small polaron hopping (SPH) theory proposed by Mott. The activation energy is found to decrease with increasing copper oxide content. The dc conductivity increases with increase in CuO content and ranging from 6.02×10-12 (?m)-1 to 1.096×10-10 (?m)-1 at 450K.

Dhiman, R. L.; Kundu, Virender Singh; Arora, Susheel; Maan, A. S.

2013-06-01

134

Assessment of cytotoxicity and oxidative effect of Bismuth Ferrite (BFO) harmonic nanoparticles for localized DNA photo-interaction  

NASA Astrophysics Data System (ADS)

Bismuth Ferrite nanoparticles have been recently used to selectively interact with malignant cell DNA via in situ generated second harmonic in a novel theranostics protocol [Nanoscale 6(5), pp. 2929, 2014]. In this report, we extend the screening of biocompatibility of BFO uncoated uncoated nanoparticles and assess the nanoparticle- mediated production of reactive oxygen species as a function of excitation wavelength.

Staedler, Davide; Magouroux, Thibaud; Passemard, Solène; Ciepielewski, Daniel; Gerber-Lemaire, Sandrine; Wolf, Jean-Pierre; Bonacina, Luigi

2014-09-01

135

Oxidized silicon nanoparticles for radiosensitization of cancer and tissue cells.  

PubMed

The applicability of ultrasmall uncapped and aminosilanized oxidized silicon nanoparticles (SiNPs and NH2-SiNPs) as radiosensitizer was studied by internalizing these nanoparticles into human breast cancer (MCF-7) and mouse fibroblast cells (3T3) that were exposed to X-rays at a single dose of 3 Gy. While SiNPs did not increase the production of reactive oxygen species (ROS) in X-ray treated cells, the NH2-SiNPs significantly enhanced the ROS formation. This is due to the amino functionality as providing positive surface charges in aqueous environment. The NH2-SiNPs were observed to penetrate into the mitochondrial membrane, wherein these nanoparticles provoked oxidative stress. The NH2-SiNPs induced mitochondrial ROS production was confirmed by the determination of an increased malondialdehyde level as representing a gauge for the extent of membrane lipid peroxidation. X-ray exposure of NH2-SiNPs incubated MCF-7 and 3T3 cells increased the ROS concentration for 180%, and 120%, respectively. Complementary cytotoxicity studies demonstrate that these silicon nanoparticles are more cytotoxic for MCF-7 than for 3T3 cells. PMID:23535374

Klein, Stefanie; Dell'Arciprete, Maria L; Wegmann, Marc; Distel, Luitpold V R; Neuhuber, Winfried; Gonzalez, Mónica C; Kryschi, Carola

2013-05-01

136

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

137

Oxidation of silicon nanoparticles produced by nanosecond laser ablation in liquids  

NASA Astrophysics Data System (ADS)

We investigated nanoparticles produced by laser ablation of silicon in water by the fundamental harmonic (1064 nm) of a ns pulsed Nd:YAG. The silicon oxidation is evidenced by IR absorption features characteristic of amorphous SiO2 (silica). This oxide is highly defective and manifests a luminescence activity under UV excitation: two emission bands at 2.7 eV and 4.4 eV are associated with the twofold coordinated silicon, =SiO••.

Vaccaro, L.; Camarda, P.; Messina, F.; Buscarino, G.; Agnello, S.; Gelardi, F. M.; Cannas, M.; Boscaino, R.

2014-10-01

138

Oxidation effects on graded porous silicon anti-reflection coatings  

E-print Network

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

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

2012-01-01

139

Cathodoluminescence and photoluminescence comparative study of erbium-doped silicon-rich silicon oxide  

NASA Astrophysics Data System (ADS)

We present a study on erbium (Er)-doped silicon (Si)-rich silicon oxide thin films grown by the magnetron cosputtering of three confocal cathodes according to the deposition temperature and the annealing treatment. It is shown that, through a careful tuning of both deposition and annealing temperatures, it is possible to engineer the fraction of agglomerated Si that may play the role of sensitizer toward Er ions. To investigate the different emitting centers present within the films according to the fraction of agglomerated Si, a cathodoluminescence experiment was made. We observe in all samples contributions from point-defect centers due to some oxygen vacancies and generally known as silicon-oxygen deficient centers (SiODC), at around 450-500 nm. The behavior of such contributions suggests the possible occurrence of an energy transfer from the SiODCs toward Er3+ ions. Photoluminescence experiments were carried out to characterize the energy transfer from Si nanoclusters toward Er3+ ions with a nonresonant wavelength (476 nm) that is unable to excite SiODCs and then exclude any role of these centers in the energy transfer process for the PL experiments. Accordingly, it is shown that structural differences have some effects on the optical properties that lead to better performance for high-temperature deposited material. This aspect is illustrated by the Er-PL efficiency that is found higher for 500°C-deposited, when compared to that for RT-deposited sample. Finally, it is shown that the Er-PL efficiency is gradually increasing as a function of the fraction of agglomerated silicon.

Cueff, Sébastien; Labbé, Christophe; Dierre, Benjamin; Cardin, Julien; Khomenkova, Larysa; Fabbri, Filippo; Sekiguchi, Takashi; Rizk, Richard

2011-01-01

140

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

141

Fundamental electrical properties of fluorinated and N2O plasma-annealed ultrathin silicon oxides grown by microwave plasma afterglow oxidation at low temperatures  

Microsoft Academic Search

A technique for growing ultrathin silicon oxides of superior quality at low temperatures is indispensable for future submicron device applications. Fundamental characteristics such as the oxide breakdown fields, oxide charges, and interface-state densities of various ultrathin silicon oxides (less than or equal to 8 nm) grown by microwave plasma afterglow oxidation at low temperatures (400 and 600 C) were investigated.

P. C. Chen; Klaus Y. J. Hsu; H. L. Hwang; J. Y. Lin

1994-01-01

142

Fundamental electrical properties of fluorinated and N2O plasma-annealed ultrathin silicon oxides grown by microwave plasma afterglow oxidation at low temperatures  

Microsoft Academic Search

A technique for growing ultrathin silicon oxides of superior quality at low temperatures is indispensable for future submicron device applications. Fundamental characteristics such as the oxide breakdown fields, oxide charges, and interface-state densities of various ultrathin silicon oxides (?8 nm) grown by microwave plasma afterglow oxidation at low temperatures (400 and 600 °C) were investigated. Fluorination (HF soaking) and low-temperature

P. C. Chen; Klaus Y. J. Hsu; H. L. Hwang; J. Y. Lin

1994-01-01

143

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

PubMed

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

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

2013-10-15

144

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

NASA Astrophysics Data System (ADS)

Bismuth ferrite films doped with neodymium on MgO single-crystal substrates with an epitaxial barium strontium titanate thin (1-2 nm) sublayer have been prepared by rf sputtering of ceramic targets at an elevated oxygen partial pressure and at temperatures below the ferroelectric and magnetic transition temperatures. It has been revealed using X-ray diffraction and Raman scattering spectroscopy that, in these bismuth ferrite films, a new phase (not observed in bulk samples) is formed. The symmetry of this phase is monoclinic, the unit cell contains two formula units, and the spontaneous polarization vector deviates from the [111]cub direction and can have different components along the x, y, and z axes.

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

2010-07-01

145

Stress dependence of paramagnetic point defects in amorphous silicon oxide.  

PubMed

Room-temperature red cathodoluminescence (CL) emission (R band) arising from the paramagnetic point-defect population present in amorphous silicon oxide (SiOx) has been characterized with respect to its shift upon applied stress, according to a piezo-spectroscopic (PS) approach. The R band (found at around 630 nm) originates from nonbridging oxygen hole centers (NBOHC; Si-O*) generated in the presence of oxygen-excess sites. It is shown that reliable stress assessments can be obtained in silica glass with a relatively high spatial resolution, provided that appropriate spectroscopic procedures are developed to precisely extract from the CL spectrum the shift upon stress of the R band, isolated from other partly overlapping bands. Macroscopic and microscopic PS calibration procedures are shown to lead to consistent results on silica materials with different chemical characteristics and, thus, with different intrinsic defect populations. In addition, quantitative calibrations of both electron probe size and luminescence emission distribution within the electron probe are given. As an application of the PS technique, the magnitude of the residual stress piled up (mainly due to a thermal expansion mismatch) at a sharp silica/silicon interface has been characterized by taking into account the gradient in defect population developed as a function of distance from the interface. In the Results and Discussion section, brief comments are offered regarding the possible impact of highly spatially resolved stress assessments in silica glass upon the development of new materials and advanced electronic devices. PMID:18380491

Leto, Andrea; Munisso, M Chiara; Porporati, A Alan; Zhu, Wenliang; Pezzotti, Giuseppe

2008-05-01

146

Laser direct writing of oxide structures on hydrogen-passivated silicon surfaces  

NASA Astrophysics Data System (ADS)

A focused laser beam has been used to induce oxidation of hydrogen-passivated silicon. The scanning laser beam removes the hydrogen passivation locally from the silicon surface, which immediately oxidizes in air. The process has been studied as a function of power density and excitation wavelength on amorphous and crystalline silicon surfaces in order to determine the depassivation mechanism. The minimum linewidth achieved is about 450 nm using writing speeds of up to 100 mm/s. The process is fully compatible with local oxidation of silicon by scanning probe lithography. Wafer-scale patterns can be generated by laser direct oxidation and complemented with nanometer resolution by scanning probe techniques. The combined micro- and nanoscale pattern can be transferred to the silicon in a single etching step by either wet or dry etching techniques.

Müllenborn, M.; Birkelund, K.; Grey, F.; Madsen, S.

1996-11-01

147

Hydrogen-Related Electrical Instabilities in MOS Capacitor of Lpcvd Silicon Oxides  

Microsoft Academic Search

Quantitative hydrogen concentration depth profiles in as-deposited and annealed LPCVD silicon oxides were determined using the nuclear reaction profiling technique with a 6.4 MeV ^{15}N ion beam. Deposited oxides of silicon with\\/without (2 -8%) phosphorus show a shift in the C-V characteristics after the oxide is annealed at temperatures >= 150^circC\\/350 ^circC. The shifts in the C-V plots are correlated

Simon Cimin Li

1992-01-01

148

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.

149

Studies of active Nd-doped silicon rich silicon oxide waveguides  

NASA Astrophysics Data System (ADS)

The Nd3+-doped Silicon Rich Silicon Oxide (SRSO) layers were elaborated by reactive magnetron cosputtering. We report on refractive index measurements of Nd3+-doped SRSO layers obtained by both m-lines method and reflectance spectroscopy. From these measurements, the Si volume fraction and also the Nd3+-doped SRSO index dispersion were deduced by using the Bruggeman model. At 1.06 ?m, work wavelength, Nd3+-doped SRSO refractive index was equal to 1.543 corresponding to a Si volume fraction of 6.5%. Optical losses measurements were performed on these waveguides at different wavelengths and were about 0.3 dB/cm at 1.55 ?m and 1 dB/cm at 1.06 ?m. Measurements are confirmed by theoretical models showing that the losses are essentially attributed to surface scattering. Guided fluorescence by top pumping at 488 nm on planar waveguides was studied as a function of the distance between the excitation area and the output of the waveguide and also as a function of the pump power. The guided fluorescence at 945 and 1100 nm was observed until 4mm of the output of the waveguide and, of course, decreased when the excitation area moved away from the output. The fluorescence intensity increased linearly for low pump power and this linear increasing of the guided fluorescence of Nd3+ excited by a non resonant excitation at 488 nm confirms the strong coupling between the Si- nanoparticles and rare earth ions.

Pirasteh, Parastesh; Charrier, Jo"l.; Dumeige, Yannick; Doualan, Jean-Louis; Camy, Patrice; Debieu, Olivier; Boucher, Yann G.; Gourbilleau, Fabrice

2012-02-01

150

Studies of active Nd-doped silicon rich silicon oxide waveguides  

NASA Astrophysics Data System (ADS)

The Nd3+-doped Silicon Rich Silicon Oxide (SRSO) layers were elaborated by reactive magnetron cosputtering. We report on refractive index measurements of Nd3+-doped SRSO layers obtained by both m-lines method and reflectance spectroscopy. From these measurements, the Si volume fraction and also the Nd3+-doped SRSO index dispersion were deduced by using the Bruggeman model. At 1.06 ?m, work wavelength, Nd3+-doped SRSO refractive index was equal to 1.543 corresponding to a Si volume fraction of 6.5%. Optical losses measurements were performed on these waveguides at different wavelengths and were about 0.3 dB/cm at 1.55 ?m and 1 dB/cm at 1.06 ?m. Measurements are confirmed by theoretical models showing that the losses are essentially attributed to surface scattering. Guided fluorescence by top pumping at 488 nm on planar waveguides was studied as a function of the distance between the excitation area and the output of the waveguide and also as a function of the pump power. The guided fluorescence at 945 and 1100 nm was observed until 4mm of the output of the waveguide and, of course, decreased when the excitation area moved away from the output. The fluorescence intensity increased linearly for low pump power and this linear increasing of the guided fluorescence of Nd3+ excited by a non resonant excitation at 488 nm confirms the strong coupling between the Si- nanoparticles and rare earth ions.

Pirasteh, Parastesh; Charrier, Joël; Dumeige, Yannick; Doualan, Jean-Louis; Camy, Patrice; Debieu, Olivier; Boucher, Yann G.; Gourbilleau, Fabrice

2011-09-01

151

Novel platinum-tin oxide-silicon nitride-silicon dioxide-silicon gas sensing component for oxygen and carbon monoxide gases at low temperature  

NASA Astrophysics Data System (ADS)

A novel gas sensing component based on a platinum-tin oxide-silicon nitride-silicon dioxide-silicon metal-insulator-semiconductor (MIS) capacitor has been developed. The new approach to integrate the catalytic properties of platinum (Pt) and the gas sensing properties of tin oxide (SnOx) with the surface-sensitive silicon MIS capacitor enhances the gas detection at lower temperature. The device is capable of detecting oxygen (O2) and carbon monoxide (CO) gases at room ambient and at temperature much lower than the operating temperature of the conventional solid state gas detectors. The gas sensing characteristics of the device and its detection mechanism for O2 and CO at 27-100 °C are presented.

Kang, W. P.; Kim, C. K.

1993-07-01

152

Oxidation behavior of green coke-based carbon–ceramic composites incorporating micro- and nano-silicon carbide  

Microsoft Academic Search

The oxidation resistance of the carbon–ceramic composites developed using green coke-based carbon and carbon black as carbon\\u000a source, boron carbide, and micro- and nano-silicon carbide was carried out in the temperature range of 800 to 1,200 °C. Silicon\\u000a carbide particulate as such and silicon carbide obtained by the reaction of green coke and silicon provided micro silicon\\u000a carbide while silicon and

Mandeep Kaur; Sandeep Kumar; P. R. Sengupta; V. Raman; G. Bhatia

2009-01-01

153

Preparation of silicon@silicon oxide core-shell nanowires from a silica precursor toward a high energy density Li-ion battery anode.  

PubMed

Bulk-quantity silicon@silicon oxide nanowires have been successfully synthesized via a facile high-temperature approach using environment-friendly silica mixed with titanium powders. It is confirmed that the obtained nanowires process a crystalline core and amorphous oxide sheath. The obtained nanowires grow along the [111] direction which catalyzed by spherical silicon@siilcon oxide nanoparticles. The unique one-dimensional structure and thin oxide sheath result in the favorable electrochemical performances, which may be beneficial to the high energy density silicon anode for lithium ion batteries. PMID:24229329

Zhang, Chuanjian; Gu, Lin; Kaskhedikar, Nitin; Cui, Guanglei; Maier, Joachim

2013-12-11

154

Photocurrent spectroscopy of Ge nanoclusters grown on oxidized silicon surface  

NASA Astrophysics Data System (ADS)

Germanium (Ge) nanoclusters are grown by a molecular-beam epitaxy technique on chemically oxidized Si(100) surface at 700ºC. Evidence for long-term photoinduced changes of surface conductivity in structures with Ge nanoclusters (NCs) grown on silicon oxide is presented. Photoexcitation NCs or Si by quanta with different energy allows observing two non-equilibrium steady-states with excess and shortage of conductivity values as compare to equilibrium one. The persistent photoconductivity (PPC) behaviour was observed after interband excitation of electron-hole pairs in Si(001) substrate. This effect may be attributed to spatial carrier separation of photoexcited electron-hole pairs by macroscopic fields in the depletion layer of near-surface Si. Photoquenching of surface conductivity, driven by optical recharging of Ge NC's and Si/SiO2 interface states, is observed. Conductivity decay is discussed in the terms of hole`s accumulation by Ge-NC states enhancing the local-potential variations and, therefore, decreasing the surface conductivity of p-Si.

Mykytiuk, A. A.; Kondratenko, S. V.; Lysenko, V. S.; Kozyrev, Yu. N.

2014-05-01

155

Emission of 1.38 microm and gain properties from Ho(3+)-doped low-phonon-energy gallate bismuth lead oxide glasses for fiber-optic amplifiers.  

PubMed

Efficient emission at 1.38 mum wavelength from holmium (Ho(3+))-doped low-phonon-energy gallate bismuth lead (GBL) oxide glasses, owing to the Ho(3+): ((5)S(2),(5)F(4))-->(5)I(5) transition, was observed, and the stimulated emission cross section was calculated to be 2.4x10(-21) cm(2). Population inversions between the ((5)S(2),(5)F(4)) and (5)I(5) levels have been achieved, and a broad gain bandwidth from 1350 to 1450 nm was obtained. The large product of emission cross section and measured lifetime also support this characteristic. The results indicate that a Ho(3+)-doped GBL glass system is a promising candidate for the development of E-band (1360-1460 nm) fiber-optic amplifiers. PMID:20081971

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

2010-01-15

156

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

157

Enhanced Growth of Thermal Oxide Due to Impurity Absorption from Adjoining Contaminated Silicon Wafers  

Microsoft Academic Search

Enhanced growth of thermal oxide at high temperature is investigated when a silicon wafer is situated behind an adjoining contaminated one. Impurities reside on the back surface of the wafer due to chucking with a stainless steel plate, depending on the surface roughness. During oxidation, the impurities spread to the adjoining wafers, causing enhanced oxide growth with the convex side

Hirofumi Shimizu; Masashi Yamamoto

1992-01-01

158

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

159

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

160

Nanophotonic devices on thin buried oxide Silicon-On-Insulator substrates  

E-print Network

. Paniccia, "A high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor," Nature hydrogen silsesquioxane electron-beam resist," Electron. Lett. 44(2), 115­116 (2008). 12. Y. Vlasov, and S

Afshari, Ehsan

161

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

E-print Network

of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235, USA Received­Si modes in the porous silicon samples. The radiation response depends strongly on initial native oxide processes wherein energetic photons are used to dissociate molecular oxygen and promote the formation

Weiss, Sharon

162

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

163

Preparation of low radioactivity spherical silicon oxide powders via chemical-flame spheroidizing process  

Microsoft Academic Search

In this work, a chemical-flame spheroidizing method was proposed to facilely prepare low radioactivity spherical silicon oxide powders. Firstly, the rice husks, composed of silicon oxide frame, were employed as the raw materials to prepare high-purity colloidal silica nanoparticles with the size 24nm via a simple “pyrolyzation–ashing–dissolvation” process. Then, the silica colloid was further treated by a spraying–drying process to

Hongyun Jin; Ning Song; Ning Wang; Yongqian Wang; Jun Zhou; Jieyu Chen; Shuen Hou

2011-01-01

164

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

DOEpatents

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

Natesan, Ken (Naperville, IL)

1994-01-01

165

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

166

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

167

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

168

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

169

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

170

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

171

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. PMID:23331713

2013-01-01

172

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

173

Characterization of microparticles and oxide layers generated by laser irradiation of diamond-machined silicon wafers  

NASA Astrophysics Data System (ADS)

Nanosecond-pulsed laser irradiation is a potential method for removing machining-induced subsurface damage from silicon wafers. In this study, the material compositions and microstructures of microparticles and oxide layers generated during laser irradiation were investigated by atomic force microscopy, energy-dispersive x-ray spectroscopy, cross-sectional transmission electron microscopy, electron energy-loss spectroscopy and Auger electron spectroscopy. The oxide layer was found to be approximately 5 nm thick, which is significantly thicker than the native oxide layer of silicon at room temperature in air (~1 nm). The microparticles have a low-density amorphous structure and are mainly composed of silicon oxide, while a few particles contain silicon. The particles are attached to the substrate, but are distinct from it. The results indicate that silicon boiled during the laser pulse and that the particles are recondensed and oxidized liquid silicon boiled away from the wafer surface. The microparticles can be completely removed from the wafer surface by hydrofluoric acid etching.

Yan, Jiwang; Sakai, Shin; Isogai, Hiromichi; Izunome, Koji

2011-02-01

174

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

175

468 IEEE ELECTRON DEVICE LETTERS, VOL. EDL-7, NO. 8, AUGUST 1986 Low-Energy Ion Beam Oxidation of Silicon  

E-print Network

468 IEEE ELECTRON DEVICE LETTERS, VOL. EDL-7, NO. 8, AUGUST 1986 Low-Energy Ion Beam Oxidation of Silicon Abstract-A low-energyoxygen ion beam with energy below 100 eV has been applied to the oxidation of unheated silicon substrates. Ultra- thin (- 45 A) FET-gate-quality oxides have been produced for the first

Fossum, Eric R.

176

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

177

Single-Longitudinal-Mode Lanthanum-Codoped Bismuth-Based Erbium Doped Fiber Ring Laser  

E-print Network

wave plates. La-codoped bismuth oxide glass is much more soluble to Er 3+ ions than silicate glass and thus high concentration of Er 3+ ions up to 13000 ppm can be doped in bismuth-based glass withoutSingle-Longitudinal-Mode Lanthanum-Codoped Bismuth-Based Erbium Doped Fiber Ring Laser K. K

Wai, Ping-kong Alexander

178

A promising biosensing-platform based on bismuth oxide polycrystalline-modified electrode: characterization and its application in development of amperometric glucose sensor.  

PubMed

Nano-structured bismuth oxide (nano-BiOx) is a suitable material for enzyme immobilization owing to its attractive properties, such as large specific surface area, suitable permeability of the resulting film, the high biocompatibility, and as well as photovoltaic effect from semiconductor nanoparticles. Thus, a new type of amperometric glucose biosensor based on nano-BiOx was constructed. The amperometric detection of glucose was assayed by potentiostating the GOD/nano-BiOx electrode at 0.5 V to oxidize the enzymatically generated hydrogen peroxide. The proposed biosensor provided a linear response to glucose over a concentration range of 1 x 10(-6) M to 1.5 x 10(-3) M with a sensitivity of 51.0+/-0.4 mA/(M cm(2)) and a detection limit of 4 x 10(-7) M based on S/N=3. The apparent Michaelis-Menten constant was calculated to be 2.9 x 10(-3) M. In addition, characterization of nano-BiOx and modified electrode was performed by FT-IR spectroscopy, Raman spectroscopy, scanning electron microscope (SEM) and rotating-disk electrode (RDE) voltammetry. PMID:20541478

Ding, Shou-Nian; Shan, Dan; Xue, Huai-Guo; Cosnier, Serge

2010-10-01

179

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

180

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

181

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

PubMed

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

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

2014-12-21

182

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

183

Silicon oxide\\/silicon nitride dual-layer films: a stacked gate dielectric for the 21st century  

Microsoft Academic Search

Incorporation of nitrogen atoms into ultra thin (<0.3 nm) gate dielectrics (i) reduces defect generation at the Si–SiO2 interface, (ii) allows use of physically thicker dielectrics when incorporated into oxide–nitride stacked gate dielectrics, and (iii) prevents boron atom transport out of heavily doped p+ polycrystalline silicon gate electrodes when nitrided layers are incorporated at the polycrystalline Si-dielectric interface. I demonstrate

Gerald Lucovsky

1999-01-01

184

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

PubMed

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

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

2013-01-01

185

Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes  

PubMed Central

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

von Borczyskowski, Christian; Graaf, Harald

2013-01-01

186

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

187

Oxidation of silicon nitride films in an oxygen plasma  

Microsoft Academic Search

The fabrication of oxynitrides using low thermal budget process technology is a key component in the production of advanced devices. This work focuses on the use of plasma anodization of low-pressure chemical vapor deposition (LPCVD) silicon nitride films to produce silicon oxynitride films, which are characterized structurally and electrically. The oxynitride dielectric films have a three layer structure, with ``SiO2''-like

G. P. Kennedy; O. Buiu; S. Taylor

1999-01-01

188

Properties of silicon oxide deposited by electron-cyclotron-resonance plasma-enhanced chemical vapor deposition  

Microsoft Academic Search

Electron cyclotron resonance plasma-enhanced chemical vapor deposition has been used to deposit silicon oxide for use as an inter-layer dielectric between high aspect ratio metal lines. The energy from a 2.45 GHz microwave field in the presence of a divergent magnetic field is absorbed by O2 and Ar gas to create a high density, low energy plasma. The silicon source

Burt W. Fowler; David R. Stark; J. Xie; P. McDonald; Ronald A. Carpio; Sha Akbar

1993-01-01

189

Indium-tin-oxide nanowhiskers crystalline silicon photovoltaics combining micro- and nano-scale surface textures  

Microsoft Academic Search

In this work, we present a solution that employs combined micro- and nano-scale surface textures to increase light harvesting in the near infrared for crystalline silicon photovoltaics, and discuss the associated antireflection and scattering mechanisms. The combined surface textures are achieved by uniformly depositing a layer of indium-tin-oxide nanowhiskers on passivated, micro-grooved silicon solar cells using electron-beam evaporation. The nanowhiskers

C. H. Chang; M. H. Hsu; W. L. Chang; W. C. Sun; Peichen Yu

2011-01-01

190

Fabrication and characterization of indium tin oxide \\/ITO\\/\\/polycrystalline silicon solar cells  

Microsoft Academic Search

Efficient indium tin oxide (ITO)\\/polycrystalline silicon heterojunction solar cells have been fabricated utilizing neutralized ion-beam sputtering techniques. These cells were fabricated on single-pass float-zone-refined silicon. Conversion efficiencies of 6.25% under AM1 illumination have been observed. Cells were analyzed by I-V characteristics and a scanning laser photoresponse technique. Qualitative minority-carrier lifetime has been mapped using the EBIC mode of a SEM.

G. Cheek; N. Inoue; S. Goodnick; A. Genis; C. Wilmsen; J. B. Dubow

1978-01-01

191

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

192

Electron and hole injection in metal-oxide-nitride-oxide-silicon structures  

SciTech Connect

The kinetics of electron and hole accumulation in metal-oxide-nitride-oxide-semiconductor structures is studied. Experimental data are compared with a theoretical model that takes into account tunnel injection, electron and hole capture by traps in amorphous silicon nitride SiN{sub x}, and trap ionization. Agreement between experimental and calculated data is obtained for the bandgap width E{sub g} = 8.0 eV of amorphous SiO{sub 2}, which corresponds to the barrier for holes {phi}{sub h} = 3.8 eV at the Si/SiO{sub 2} interface. The tunneling effective masses for holes in SiO{sub 2} and SiN{sub x} are estimated at m{sub h}{sup *} {approx} (0.4-0.5)m{sub 0}. The parameters of electron and hole traps in SiN{sub x} are determined within the phonon-coupled trap model: the optical energy W{sub opt} = 2.6 eV and the thermal energy W{sub T} = 1.3 eV.

Nasyrov, K. A. [Russian Academy of Sciences, Institute of Automatics and Electrometry, Siberian Division (Russian Federation); Shaimeev, S. S.; Gritsenko, V. A. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Division (Russian Federation)], E-mail: grits@isp.nsc.ru; Han, J. H.; Kim, C. W.; Lee, J.-W. [Samsung Advanced Institute of Technology (Korea, Republic of)

2006-05-15

193

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

SciTech Connect

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

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

2011-07-31

194

Nanostructurized Forms of Bismuth  

Microsoft Academic Search

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

Oxana V. Kharissova; Boris I. Kharisov

2008-01-01

195

High charge storage of poly-Si thin film nonvolatile memory devices with oxide–silicon–oxynitride stack structures  

Microsoft Academic Search

Polycrystalline silicon (poly-Si) thin film nonvolatile memory (NVM) devices with an oxide–silicon–oxynitride (OSOn) stack structure using an amorphous silicon (a-Si) as a storage layer on a glass panel were fabricated and investigated for high charge storage of memory applications in systems-on-panels (SOPs). Because the band gap of a-Si is lower than that of silicon nitride (SiNx) and a larger band

Sungwook Jung; Kyungsoo Jang; Youn-Jung Lee; Zhenghai Jin; Junsin Yi

2010-01-01

196

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

197

Resistance of silicon nitride turbine components to erosion and hot corrosion/oxidation attack  

NASA Technical Reports Server (NTRS)

Silicon nitride turbine components are under intensive development by AlliedSignal to enable a new generation of higher power density auxiliary power systems. In order to be viable in the intended applications, silicon nitride turbine airfoils must be designed for survival in aggressive oxidizing combustion gas environments. Erosive and corrosive damage to ceramic airfoils from ingested sand and sea salt must be avoided. Recent engine test experience demonstrated that NT154 silicon nitride turbine vanes have exceptional resistance to sand erosion, relative to superalloys used in production engines. Similarly, NT154 silicon nitride has excellent resistance to oxidation in the temperature range of interest - up to 1400 C. Hot corrosion attack of superalloy gas turbine components is well documented. While hot corrosion from ingested sea salt will attack silicon nitride substantially less than the superalloys being replaced in initial engine applications, this degradation has the potential to limit component lives in advanced engine applications. Hot corrosion adversely affects the strength of silicon nitride in the 850 to 1300 C range. Since unacceptable reductions in strength must be rapidly identified and avoided, AlliedSignal and the NASA Lewis Research Center have pioneered the development of an environmental life prediction model for silicon nitride turbine components. Strength retention in flexure specimens following 1 to 3300 hour exposures to high temperature oxidation and hot corrosion has been measured and used to calibrate the life prediction model. Predicted component life is dependent upon engine design (stress, temperature, pressure, fuel/air ratio, gas velocity, and inlet air filtration), mission usage (fuel sulfur content, location (salt in air), and times at duty cycle power points), and material parameters. Preliminary analyses indicate that the hot corrosion resistance of NT154 silicon nitride is adequate for AlliedSignal's initial engine applications. Protective coatings and/or inlet air filtration may be required to achieve required ceramic component lives in more aggressive environments.

Strangmen, Thomas E.; Fox, Dennis S.

1994-01-01

198

Oxide films for solar cells obtained by the extraction pyrolytic method  

Microsoft Academic Search

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

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

2009-01-01

199

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

200

a Study of the Synthesis, Structures and Superconductivity of BARIUM(1-X) Potassium (x) Bismuth Oxide System  

Microsoft Academic Search

Ba_{1-x}K _{x}BiO _3 compound is a superconducting system with Tc ~ 30K. This system plays a very important role between conventional BCS superconductors and high T_{c} Cu-oxide systems. It has the highest T_ {c} among all the non-Cu oxide superconductors. And it is much simpler, structurally and electronically, compared with high T_ {c} Cu-based systems. This system is 3-D isotropic--simple

Ying Zheng

1991-01-01

201

Effects of Water Adsorption and Surface Oxidation on the Electrical Conductivity of Silicon Nanocrystal Films  

NASA Astrophysics Data System (ADS)

Electrical conductivities of thin films of silicon nanocrystals (4-6 nm) exhibit high sensitivity to water vapor. Specifically, water adsorption on the surface of silicon nanocrystal (NC) films increases their electrical conductivity by a factor of four at room temperature and an order of magnitude at 175 K. The increase in conductivity is reversible and can manifest as peaks or hysteresis loops in temperature-dependent conductivity measurements even when the measurements are conducted under vacuum at 10-5 Torr and in the presence of only residual amounts of water vapor. Hydrogen-terminated silicon nanocrystals are easily oxidized to form submonolayer to monolayer of chemically bound oxygen on their surfaces when annealed at 300°C in a glovebox with 0.1 ppm of water vapor. Annealing under vacuum at 300°C retains H-passivation without oxidation. The electrical conductivity of films made from hydrogen-terminated silicon nanocrystals is 200 times higher than the electrical conductivity of films made from silicon nanocrystals with a monolayer of chemically bound oxygen. However, the conductivities of both types of films increase upon adsorption of water on the nanocrystal surfaces. These findings underscore the importance of controlling silicon nanocrystal surfaces in determining the electrical properties of their thin films.

Rastgar, Neema

202

Low-index nanopatterned barrier for hybrid oxide-free III-V silicon conductive bonding.  

PubMed

Oxide-free bonding of a III-V active stack emitting at 1300-1600 nm to a silicon-on-insulator wafer offers the capability to electrically inject lasers from the silicon side. However, a typical 500-nm-thick silicon layer notably attracts the fundamental guided mode of the silicon + III-V stack, a detrimental feature compared to established III-V Separate-Confinement Heterostructure (SCH) stacks. We experimentally probe with photoluminescence as an internal light source the guiding behavior for oxide-free bonding to a nanopatterned silicon wafer that acts as a low-index barrier. We use a sub-wavelength square array of small holes as an effective "low-index silicon" medium. It is weakly modulated along one dimension (superperiodic array) to outcouple the resulting guided modes to free space, where we use an angle-resolved spectroscopy study. Analysis of experimental branches confirms the capability to operate with a fundamental mode well localized in the III-V heterostructures. PMID:25321802

Bougot-Robin, Kristelle; Talneau, Anne; Benisty, Henri

2014-09-22

203

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. PMID:22067075

2011-01-01

204

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

205

Development of an oxidized porous silicon vacuum microtriode  

E-print Network

the requirements for a gigatron cathode. In the present work, a porous sihcon-based approach is evaluated. The use of porous silicon reduces the size of a single emitter to the manometer scale, and a true two-dimensional array geometry can be approached. A wide...

Smith, Don Deewayne

2012-06-07

206

Doped and Undoped Zinc Oxide Nanostructures on Silicon Wafers  

NASA Astrophysics Data System (ADS)

We present results of hydrothermal deposition of undoped and Al doped ZnO nanocrystals on nanocrystalline silicon. ZnO nanocrystals were deposited in an equimolar zinc nitride and hexamethylenetetramine solution. Aluminum nitride was used as Al precursor. The difference of the morphology of doped and undoped ZnO nanocrystals is discussed. Photoluminescence properties of the obtained nanocrystals are shown.

Chubenko, E.; Bondarenko, V.

2013-05-01

207

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

208

Adaptable silicon-carbon nanocables sandwiched between reduced graphene oxide sheets as lithium ion battery anodes.  

PubMed

Silicon has been touted as one of the most promising anode materials for next generation lithium ion batteries. Yet, how to build energetic silicon-based electrode architectures by addressing the structural and interfacial stability issues facing silicon anodes still remains a big challenge. Here, we develop a novel kind of self-supporting binder-free silicon-based anodes via the encapsulation of silicon nanowires (SiNWs) with dual adaptable apparels (overlapped graphene (G) sheaths and reduced graphene oxide (RGO) overcoats). In the resulted architecture (namely, SiNW@G@RGO), the overlapped graphene sheets, as adaptable but sealed sheaths, prevent the direct exposure of encapsulated silicon to the electrolyte and enable the structural and interfacial stabilization of silicon nanowires. Meanwhile, the flexible and conductive RGO overcoats accommodate the volume change of embedded SiNW@G nanocables and thus maintain the structural and electrical integrity of the SiNW@G@RGO. As a result, the SiNW@G@RGO electrodes exhibit high reversible specific capacity of 1600 mAh g?¹ at 2.1 A g?¹, 80% capacity retention after 100 cycles, and superior rate capability (500 mAh g?¹ at 8.4 A g?¹) on the basis of the total electrode weight. PMID:23281801

Wang, Bin; Li, Xianglong; Zhang, Xianfeng; Luo, Bin; Jin, Meihua; Liang, Minghui; Dayeh, Shadi A; Picraux, S T; Zhi, Linjie

2013-02-26

209

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

210

Inhibition of field crystallization of anodic niobium oxide by incorporation of silicon species  

Microsoft Academic Search

The present work demonstrates effective inhibition of field crystallization of amorphous anodic niobium oxide by incorporation of silicon species from substrate. The field crystallization, detrimental for capacitor application of niobium, occurs during anodizing of magnetron sputtered niobium at 100V in 0.1moldm?3 ammonium pentaborate electrolyte at 333K, while amorphous structure of the anodic oxide is totally retained during anodizing of magnetron

H. Habazaki; T. Ogasawara; K. Fushimi; K. Shimizu; S. Nagata; T. Izumi; P. Skeldon; G. E. Thompson

2008-01-01

211

Charge separation technique for metal–oxide–silicon capacitors in the presence of hydrogen deactivated dopants  

Microsoft Academic Search

An improved charge separation technique for metal–oxide–silicon (MOS) capacitors is presented which accounts for the deactivation of substrate dopants by hydrogen at elevated irradiation temperatures or small irradiation biases. Using high-frequency capacitance–voltage measurements, radiation-induced inversion voltage shifts are separated into components due to oxide trapped charge, interface traps, and deactivated dopants, where the latter is computed from a reduction in

Steven C. Witczak; Peter S. Winokur; Ronald C. Lacoe; Donald C. Mayer

2000-01-01

212

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

Microsoft Academic Search

An improved charge separation technique for metal-oxide-silicon (MOS) capacitors is presented which accounts for the deactivation of substrate dopants by hydrogen at elevated irradiation temperatures or small irradiation biases. Using high-frequency capacitance-voltage measurements, radiation-induced inversion voltage shifts are separated into components due to oxide trapped charge, interface traps, and deactivated dopants, where the latter is computed from a reduction in

Steven C. Witczak; Peter S. Winokur; Ronald C. Lacoe; Donald C. Mayer

2000-01-01

213

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

214

Labyrinth patterns of zinc oxide on porous silicon substrate  

NASA Astrophysics Data System (ADS)

The substrate treatment dependent formation of different micro-morphologies of zinc oxide over PS substrate has been reported. Effect of substrate oxidation and annealing has been studied. Changes in the structural properties were seen in the form of labyrinth patterns developed on the surface and were studied with the help of scanning electron microscope (SEM), atomic force microscope (AFM). X-ray diffraction (XRD) along with UV-visible absorption and photoluminescence (PL) spectroscopy were performed for characterizing the zinc oxide film and the hybrid structure. A relatively flat film of nanostructured zinc oxide particles is found to form on the oxidized substrate as compared to the nanostructured labyrinth patterns formed on the un-oxidized substrate with enhanced aspect ratio. Such micromorphologies can be very promising for fabricating highly sensitive gas sensors.

Martínez, L.; Kumar, Y.; Mayorga, D.; Goswami, N.; Agarwal, V.

2014-03-01

215

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

216

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

217

Influence of reaction conditions on sol-precipitation process producing silicon oxide particles  

Microsoft Academic Search

The influence of TEOS, water, and ammonia concentrations on the sol-precipitation process for producing silicon oxide particles was investigated. When the hydrolysis and condensation were assumed as simple first-order reactions, the hydrolysis and condensation reaction coefficients were enhanced with an increase in the ammonia concentration due to its catalytic role in the reactions. Likewise, the increased hydrolysis coefficient with increased

Kyung-Soo Kim; Jun-Kyung Kim; Woo-Sik Kim

2002-01-01

218

Characterization of highly hydrophobic coatings deposited onto pre-oxidized silicon from water dispersible organosilanes  

Microsoft Academic Search

The formation and quality of highly hydrophobic coatings deposited from water dispersible organosilanes onto pre-oxidized single crystal silicon were studied using atomic force microscopy, ellipsometry, dynamic contact angle measurements and electrochemical impedance spectroscopy (EIS). Highly hydrophobic films of a commercially available water dispersible silane and two different cationic alkoxysilanes were prepared by dip coating. It was found using atomic force

A. Marcia Almanza-Workman; Srini Raghavan; Slobodan Petrovic; Bishnu Gogoi; Pierre Deymier; David J. Monk; Ray Roop

2003-01-01

219

Strong green-yellow electroluminescence from oxidized amorphous silicon nitride light-emitting devices  

Microsoft Academic Search

High efficiency luminescent amorphous silicon nitride films grown at room temperature with subsequent plasma oxidation were used as the active layers in the electroluminescent devices. A strong uniform green-yellow light emission from the devices was realized under forward biased conditions. It was found that the turn-on voltage could be reduced to as low as 6 V while the electroluminescence (EL)

Rui Huang; Kunji Chen; Peigao Han; Hengping Dong; Xiang Wang; Deyuan Chen; Wei Li; Jun Xu; Zhongyuan Ma; Xinfan Huang

2007-01-01

220

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

221

Translocation of double-strand DNA through a silicon oxide nanopore A. J. Storm,1  

E-print Network

Translocation of double-strand DNA through a silicon oxide nanopore A. J. Storm,1 J. H. Chen,1,2 H. W. Zandbergen,1 and C. Dekker1 1 Kavli Institute of Nanoscience, Delft University of Technology of a voltage-biased pore, we detect molecules with a length ranging from 6557 to 48 500 base pairs. We find

Dekker, Cees

222

A Nanoindentation Study of Thermally-Grown-Oxide Films on Silicon Fatih Helvaci and Junghyun Cho  

E-print Network

A Nanoindentation Study of Thermally-Grown-Oxide Films on Silicon Fatih Helvaci and Junghyun Cho films using a depth- sensing indentation. For this purpose, nanoindentation has been performed `film- only' mechanical properties from the nanoindentation data by subtracting the substrate effect

Cho, Junghyun

223

Effect of Oxide on Trench Edge Defect Formation in Ion-Implanted Silicon  

E-print Network

during high-temperature pro- cessing but may also occur during solid-phase epitaxy SPE of amorphous Si is the mi- gration of point defects to regions of high stress generated by pat- terned structuresEffect of Oxide on Trench Edge Defect Formation in Ion-Implanted Silicon N. Burbure, N. G. Rudawski

Florida, University of

224

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

Microsoft Academic Search

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

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

1998-01-01

225

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

226

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. PMID:24948891

2014-01-01

227

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

228

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

229

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

SciTech Connect

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

Dominique Krzeminski, Christophe, E-mail: christophe.krzeminski@isen.fr [Départment ISEN, IEMN-UMR-8520, 41 Boulevard Vauban, 59046 Lille Cedex (France)

2013-12-14

230

Graphene oxide-immobilized NH?-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

231

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

232

The fabrication and preservation of nanostructures on silicon wafers with a native oxide layer.  

PubMed

This study used nano-oxidation lithography to create oxidized circular nanostructures on a silicon wafer with a native oxide layer (NOL). We also investigated the impact of wet etching on the size of circular oxidized nanostructures and examined how the method and duration of preservation affect them. Experimental results show that the height and width of oxidized circular nanostructures increase proportionally with applied voltage. After wet etching, an increase in applied voltage resulted in a marked increase in the width of the circular nanostructures, a decrease in the inner diameter, and little variation in height. We further demonstrated that in a moist environment, the oxidation process continues, resulting in a further increase in height and width. During the initial stages of preservation, these changes occurred rapidly; however, the increase was negligible after 30 days. We propose the concept of reaction area (RA) ratio to explain the above phenomenon and provide evidence to support these claims. Our results led us to a simple and yet effective method of preserving oxidized circular nanostructures, called the electrostatic patch preservation (EPP) method, to overcome problems associated with changes in size occurring during the preservation of silicon nanostructure molds. PMID:22331793

Huang, Jen-Ching; Wang, Jui-Yang

2012-01-01

233

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

SciTech Connect

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

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

2012-01-01

234

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

SciTech Connect

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

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

2012-09-30

235

Surface chemistry, reactivity, and pore structure of porous silicon oxidized by various methods.  

PubMed

Oxidation is the most commonly used method of passivating porous silicon (PSi) surfaces against unwanted reactions with guest molecules and temporal changes during storage or use. In the present study, several oxidation methods were compared in order to find optimal methods able to generate inert surfaces free of reactive hydrides but would cause minimal changes in the pore structure of PSi. The studied methods included thermal oxidations, liquid-phase oxidations, annealings, and their combinations. The surface-oxidized samples were studied by Fourier transform infrared spectroscopy, isothermal titration microcalorimetry, nitrogen sorption, ellipsometry, X-ray diffraction, electron paramagnetic resonance spectroscopy, and scanning electron microscopy imaging. Treatment at high temperature was found to have two advantages. First, it enables the generation of surfaces free of hydrides, which is not possible at low temperatures in a liquid or a gas phase. Second, it allows the silicon framework to partially accommodate a volume expansion because of oxidation, whereas at low temperature the volume expansion significantly consumes the free pore volume. The most promising methods were further optimized to minimize the negative effects on the pore structure. Simple thermal oxidation at 700 °C was found to be an effective oxidation method although it causes a large decrease in the pore volume. A novel combination of thermal oxidation, annealing, and liquid-phase oxidation was also effective and caused a smaller decrease in the pore volume with no significant change in the pore diameter but was more complicated to perform. Both methods produced surfaces that were not found to react with a model drug cinnarizine in isothermal titration microcalorimetry experiments. The study enables a reasonable choice of oxidation method for PSi applications. PMID:22671967

Riikonen, Joakim; Salomäki, Mikko; van Wonderen, Jessica; Kemell, Marianna; Xu, Wujun; Korhonen, Ossi; Ritala, Mikko; MacMillan, Fraser; Salonen, Jarno; Lehto, Vesa-Pekka

2012-07-17

236

Silicon-Steel Magnesium Oxide Fabricated from Light-Burned Magnesia  

NASA Astrophysics Data System (ADS)

In this work, silicon-steel magnesium oxide was fabricated from light-burned magnesia by several steps. Light-burned magnesia was first slaked and carbonated to afford magnesium bicarbonate liquor and then the impurities in the liquor were removed by activated carbon. The purified liquor was then pyrolyzed to obtain basic magnesium carbonate which was calcined to result in silicon-steel magnesium oxide. The effects of carbonization time and solid to liquid ratio on the leaching process were discussed, and the impacts of adsorption temperature and time on removing impurities were also investigated. An insight into pyrolytic temperature, time and temperature rise rate indicates that fast temperature rising and high temperature lead to magnesia powders with large particle size while pyrolytic time has little effect on the particle size of magnesium oxide. The results show that the mass fraction of MgO in silicon-steel magnesium oxide is more than 99.5%, the mass fractions of CaO and Fe are less than 0.09% and 0.05%, boron content between 30-1000 ppm and more than 72.3% of magnesia particles are less than 5 µ in size by means of this process.

Zhong, Jianchu; Wang, Yafang; Wang, Hongzhi; Hu, Desheng

237

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

PubMed

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

Pennelli, G; Totaro, M; Piotto, M

2012-02-01

238

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  

Microsoft Academic Search

This research project deals with the feasibility studies concerning the construction of an hybrid reactor for the transmutation of long-lived radioactive wastes. In this context, the liquid 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

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

2008-01-01

239

a Study of the Synthesis, Structures and Superconductivity of BARIUM(1-X) Potassium (x) Bismuth Oxide System  

NASA Astrophysics Data System (ADS)

Ba_{1-x}K _{x}BiO _3 compound is a superconducting system with Tc ~ 30K. This system plays a very important role between conventional BCS superconductors and high T_{c} Cu-oxide systems. It has the highest T_ {c} among all the non-Cu oxide superconductors. And it is much simpler, structurally and electronically, compared with high T_ {c} Cu-based systems. This system is 3-D isotropic--simple cubic perovskite; it has only s and p (no d) electrons at Fermi surface; and it has no magnetism. Understanding the nature of the superconductivity in this system will help us test the limitations of the conventional BCS-type superconductivity. 1. We successfully make a whole series of single phase Ba_{1-x}K _{x}BiO _3 samples with 0 <= x<= 0.5 using our 2-step synthesis method. A combination of x-ray, NPD, TGA, DTA, and SEM techniques has been used to study the chemistry behavior in this system. The results show that the superconducting phase of Ba _{1-x}K_{x}BiO_3 is a metastable phase. 2. Structural phase diagram of Ba_{1-x}K_{x}BiO_3 system is determined by neutron scattering experiment. There are five different phases observed in the regions of 0 <= x<= 0.5 and 10K <= T<= 473K. At room temperature, with potassium doping, system goes from monoclinic phase to orthorhombic phase at x ~ 0.1 and to cubic phase at x ~ 0.35. The superconducting phase is a cubic phase. 3. Susceptibility measurement shows that our Ba_{1-x}K _{x}BiO_3 samples with 0.325 <= x <= 0.5 are bulk superconducting materials and the superconductivity occurs (with the highest T _{c}) around the orthorhombic -cubic phase transition (x ~ 0.35), and the T_{c} of the system decreases with increase in potassium. Resistivity measurement also observes a semiconducting-metallic transition near the orthorhombic-cubic phase transition. 4. Oxygen isotope experiment shows that the mechanism of the superconductivity in Ba_{1-x}K_{x} BiO_3 system may be the oxygen phonon-mediated e-e interaction. When combined with the data from inelastic neutron scattering, IR spectroscopy, and tunneling, etc, we conclude that the high T _{c} behavior in this system may be due to the coupling of electrons to the high energy ( ~ 40meV) optical oxygen phonons and the superconductivity in this system can be explained well by the BCS-based theory.

Zheng, Ying

1991-02-01

240

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

241

Effects of hydrogen chloride on boron acceptor hydrogenation and trap generation-annealing in oxidized silicon irradiated by keV electrons  

Microsoft Academic Search

The effects of hydrogen chloride (HCl) during oxidation of silicon on the hydrogenation of boron acceptors and generation-annealing of interface and oxide traps are reported in 8-keV electron irradiated aluminum\\/polycrystalline-silicon\\/oxide\\/silicon capacitors. This paper shows (i) boron acceptor hydrogenation also occurs during HCl oxidation, a new finding, (ii) boron acceptor hydrogenation continues after the electron beam was turned off, (iii) interfacial

Wallace Wan-Li Lin; Chih-Tang Sah

1988-01-01

242

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. PMID:23536541

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

2013-01-01

243

Enhanced electroluminescence from nanoscale silicon p+ -n junctions made with an anodic aluminum oxide pattern.  

PubMed

An enhancement of the electroluminescence (EL) from nanoscale silicon p(+)-n junctions made with an anodic aluminum oxide (AAO) pattern was demonstrated. The nanoporous AAO pattern with a pore density of 1.4 x 10(10) cm(-2) and a pore diameter of 50 +/- 10 nm was fabricated by the two-step anodic oxidation method on a n-type silicon wafer. The nanoscale AAO patterned Si p(+)-n junctions achieved an EL enhancement factor up to about 5 compared to the unpatterned Si p(+)-n junctions. The enhancement may originate from a reduction of nonradiative recombination due to partial passivation of the Si surface by the AAO pattern and improvement of the light extraction due to surface nanotextures. PMID:19955614

Hong, T; Chen, T; Ran, G Z; Wen, J; Li, Y Z; Dai, T; Qin, G G

2010-01-15

244

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

245

Complete coverage of reduced graphene oxide on silicon dioxide substrates  

NASA Astrophysics Data System (ADS)

Reduced graphene oxide (RGO) has the advantage of an aqueous and industrial-scale production route. No other approaches can rival the RGO field effect transistor platform in terms of cost (oxide with ethanol, carbon islets are deposited preferentially at the edges of existing flakes. With a 2-h treatment, the standard deviation in electrical resistance of the treated chips can be reduced by 99.95%. Thus this process could enable RGO to be used in practical electronic devices.

Huang, Jingfeng; Melanie, Larisika; Chen, Hu; Steve, Faulkner; Myra, A. Nimmo; Christoph, Nowak; Alfred Tok Iing, Yoong

2014-08-01

246

Evolution of oxidation and creep damage mechanisms in HIPed silicon nitride materials  

Microsoft Academic Search

Several yttria-fluxed, hot-isostatically pressed (HIPed) silicon nitrides have been tensile creep tested at temperatures representative of gas turbine engines. Creep and oxidation assisted damage mechanisms concurrently evolve when these materials are tested at high temperatures and low stresses (i.e., long exposure times at temperature). Atmospheric creep testing results in creation of oxygen and yttrium gradients across the radial dimension. High

A. A. Wereszczak; M. K. Ferber; T. P. Kirkland; K. L. More

1994-01-01

247

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

248

Luminescence of the cadmium telluride quantum dots in the porous silicon oxide  

NASA Astrophysics Data System (ADS)

The luminescence of the CdTe quantum dots deposited on glass substrate and introduced into the porous silicon oxide matrix is investigated. The experimental results on the photoluminescence with one- and two-photon excitation and cathodoluminescence indicate that the quantum dots introduced into the matrix retain the luminescence properties. The coefficient of the two-photon absorption of the CdTe quantum dots on the glass substrate is determined.

Piskunov, N. A.; Maslennikov, E. D.; Golovan, L. A.; Kashkarov, P. K.; Ostapenko, I. A.; Rodt, S.; Bimberg, D.

2011-03-01

249

Gas barrier properties of silicon oxide films prepared by plasma-enhanced CVD using tetramethoxysilane  

Microsoft Academic Search

Silicon oxide films were deposited by means of capacitively coupled RF plasma-enhanced CVD using a mixture of tetramethoxysilane and oxygen as source. Chemical compositions and bonding states of the deposited films were analyzed by FTIR and XPS. The absorption bands due to Si–CH3, Si–H and Si–OH in the FTIR spectra became markedly smaller when the RF power and the fraction

K Teshima; Y Inoue; H Sugimura; O Takai

2002-01-01

250

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

251

Positron annihilation study of defects and Si nanoprecipitation in sputter-deposited silicon oxide films  

Microsoft Academic Search

Positron annihilation spectroscopy was conducted to study defects and Si nanoprecipitation in sputter-deposited silicon oxide films. For as-deposited SiO0.9 and SiO1.9 films, Doppler broadening spectra are strongly influenced by the type of paramagnetic defects (Pb or E?). However, the disappearance of these defects after annealing at 1050 °C in a vacuum cannot account for the corresponding change of the Doppler

R. S. Yu; K. Ito; K. Hirata; K. Sato; W. Zheng; Y. Kobayashi

2003-01-01

252

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

Microsoft Academic Search

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

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

2005-01-01

253

Patterns of discoloration and oxidation by direct and scattered fluxes, especially oxygen on silicon  

NASA Technical Reports Server (NTRS)

A number of interesting discoloration patterns are clearly evident on M0002-1 which resides on three faces of LDEF: front face, rear face, and earth face. Most interesting is the pattern of blue oxidation on polished single crystal silicon apparently produced by once-scattered ram oxygen atoms along the earth face. Most of the other patterns are seen in the Thermal Control Paint. Also, severe oxidation of CR-39 polycarbonate occurred on the front face of LDEF, as expected. A complete explanation for the patterns has not yet been obtained.

Frederickson, A. R.; Filz, R. C.; Rich, F. J.; Sagalyn, Paul L.

1991-01-01

254

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

NASA Technical Reports Server (NTRS)

An analysis is made of the waveguiding properties of the oxygen-implanted, buried-oxide, silicon-on-insulator structures currently being developed for use in microelectronics. It is found that in spite of the fact that the buried-oxide layer is only a few tenths of a micrometer thick, the single-crystal overlayer can support TEo guided-wave propagation, at subbandgap wavelengths, with losses due to substrate radiation leakage at or below the benchmark level of 1 dB/cm.

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

1988-01-01

255

Window layer with p doped silicon oxide for high Voc thin-film silicon n-i-p solar cells  

NASA Astrophysics Data System (ADS)

We investigate the influence of the oxygen content in boron-doped nanocrystalline silicon oxide films (p-nc-SiOx) and introduce this material as window layer in n-i-p solar cells. The dependence of both, optical and electrical properties on the oxygen content is consistent with a bi-phase model which describes the p-nc-SiOx material as a mixture of an oxygen-rich (O-rich) phase and a silicon-rich (Si-rich) phase. We observe that increasing the oxygen content enhances the optical gap E04 while deteriorating the activation energy and the planar conductivity. These trends are ascribed to a higher volume fraction of the O-rich phase. Incorporated into n-i-p a-Si:H cells, p-nc-SiOx layers with moderate oxygen content yield open circuit voltage (Voc) up to 945 mV, which corresponds to a relative gain of 11% compared to an oxygen-free p-layer. As a similar gain is obtained on planar and on textured substrates, we attribute the increase in Voc to the higher work function of the p-nc-SiOx layer made possible by its wider band gap. These results are attained without changing the dilution ratio of the 250 nm thick intrinsic layer. We also observe an enhancement of 0.6 mA cm-2 in short circuit current density in the short wavelengths due to the higher transparency of the p-nc-SiOx layer. Finally, an initial efficiency of 9.9% for a single junction 250 nm a-Si:H n-i-p solar cell on plastic foil is achieved with the optimization of the p layer thickness, the doping ratio of the front transparent conductive oxide, and the optical properties of the back reflector.

Biron, Rémi; Pahud, Celine; Haug, Franz-Josef; Escarré, Jordi; Söderström, Karin; Ballif, Christophe

2011-12-01

256

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

257

Competitive gettering of iron in silicon photovoltaics: Oxide precipitates versus phosphorus diffusion  

NASA Astrophysics Data System (ADS)

Experiments have been conducted to understand the behaviour of iron in silicon containing oxide precipitates and associated defects (dislocations and stacking faults), which is subjected to phosphorus diffusion gettering. Injection-dependent minority carrier lifetime measurements are analysed to provide quantitative information on the degree to which the precipitates and associated defects are decorated with iron impurities. These data are correlated with bulk iron measurements based on the photodissociation of FeB pairs. Iron in the vicinity of oxide precipitates in samples with relatively low levels of bulk iron contamination (< 5 × 1012 cm-3) can be gettered to some extent. Higher levels of bulk iron contamination (> 1.2 × 1013 cm-3) result in irreversible behaviour, suggesting iron precipitation in the vicinity of oxide precipitates. Bulk iron is preferentially gettered to the phosphorus diffused layer opposed to the oxide precipitates and associated defects.

Murphy, J. D.; McGuire, R. E.; Bothe, K.; Voronkov, V. V.; Falster, R. J.

2014-08-01

258

Enhanced reduction of silicon oxide thin films on silicon under electron beam annealing  

NASA Astrophysics Data System (ADS)

Electron beam annealing is an interesting alternative to other annealing methods as it can provide high temperature, rapid heating and cooling and low level of impurity as it operates under high vacuum environment. Furthermore swamping the materials with electrons can lead to dramatic changes in the component valence states with the mechanism involving oxido-reduction reactions. This is illustrated in the present case with the enhancement of the reduction of SiO2. Commercial thermally grown 100 and 400 nm SiO2 films on Si were annealed under three different environments: furnace annealing in open atmosphere with O2 flow, high vacuum furnace annealing and electron beam annealing. The reduction and oxidation of SiO2 films on Si are investigated using ion beam analysis. The validity of the measurement method was confirmed by measuring the oxidation rate through successive Rutherford backscattering spectrometry (RBS) measurements. The oxidation kinetics were observed to be in excellent agreement with literature values. At 1000 °C reduction of the SiO2 film is observed only with electron beam annealing. A model is proposed to explain the effect of the electron beam.

Kennedy, J.; Leveneur, J.; Fang, F.; Markwitz, A.

2014-08-01

259

Effect of annealing ambient on the removal of oxide precipitates in high-dose oxygen implanted silicon  

NASA Astrophysics Data System (ADS)

The effect of annealing ambient on the precipitate removal processes in high-dose oxygen implanted silicon [separation by implantation of oxygen (SIMOX)] has been studied with transmission electron microscopy, electron energy-loss spectroscopy, and secondary ion mass spectroscopy. The rate of removal of oxide precipitates from the top silicon layer in SIMOX is higher during annealing in argon than in nitrogen. The removal is reduced in nitrogen due to the formation of an oxynitride complex at the precipitate surfaces which inhibits oxygen diffusion across the interfaces. Similar effects have been observed for oxide precipitation during nitrogen ambient annealing in bulk silicon.

Seraphin, Supapan; Krause, Stephen J.; Roitman, Peter; Simons, David S.; Cordts, Bernhard F.

1991-12-01

260

Chemical stability of the magnetic oxide EuO directly on silicon observed by hard x-ray photoemission spectroscopy  

NASA Astrophysics Data System (ADS)

We present a detailed study of the electronic structure and chemical state of high-quality stoichiometric EuO and O-rich Eu1O1+x thin films grown directly on silicon without any buffer layer using hard x-ray photoemission spectroscopy (HAXPES). We determine the EuO oxidation state from a consistent quantitative peak analysis of 4f valence band and 3d core-level spectra. The results prove that nearly ideal, stoichiometric, and homogeneous EuO thin films can be grown on silicon, with a uniform depth distribution of divalent Eu cations. Furthermore, we identify the chemical stability of the EuO/silicon interface from Si 2p core-level photoemission. This work clearly demonstrates the successful integration of high-quality EuO thin films directly on silicon, opening up the pathway for the future incorporation of this functional magnetic oxide into silicon-based spintronic devices.

Caspers, C.; Müller, M.; Gray, A. X.; Kaiser, A. M.; Gloskovskii, A.; Fadley, C. S.; Drube, W.; Schneider, C. M.

2011-11-01

261

Influence of N2O oxidation of silicon on point defect injection kinetics in the high temperature regime  

Microsoft Academic Search

In this work we investigate the influence of N2O oxidation on the kinetics of point defects at high temperatures. The interstitials that are injected during the oxidation process are monitored by the growth of preexisting oxidation stacking faults. We show that at high temperatures (1050–1150 °C), the supersaturation of self-interstitials in the silicon substrate is enhanced when oxidation is performed

C. Tsamis; D. N. Kouvatsos; D. Tsoukalas

1996-01-01

262

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

263

Silicon surface deoxidation using strontium oxide deposited with the pulsed laser deposition technique.  

PubMed

The epitaxial growth of functional oxides on silicon substrates requires atomically defined surfaces, which are most effectively prepared using Sr-induced deoxidation. The manipulation of metallic Sr is nevertheless very delicate and requires alternative buffer materials. In the present study the applicability of the chemically much more stable SrO in the process of native-oxide removal and silicon-surface stabilization was investigated using the pulsed-laser deposition technique (PLD), while the as-derived surfaces were analyzed in situ using reflection high-energy electron diffraction and ex situ using X-ray photoelectron spectroscopy, X-ray reflectivity, and atomic force microscopy. After the deposition of the SrO over Si/SiO2, in a vacuum, different annealing conditions, with the temperature ranging up to 850 °C, were applied. Because the deposition took place in a vacuum, a multilayer composed of SrO, Sr-silicate, modified Si, and Si as a substrate was initially formed. During the subsequent annealing the topmost layer epitaxially orders in the form of islands, while a further increase in the annealing temperature induced rapid desorption and surface deoxidation, leading to a 2 × 1 Sr-reconstructed silicon surface. However, the process is accompanied by distinctive surface roughening, and therefore the experimental conditions must be carefully optimized to minimize the effect. The results of the study revealed, for the first time, an effective pathway for the preparation of a SrO-induced buffer layer on a silicon substrate using PLD, which can be subsequently utilized for the epitaxial growth of functional oxides. PMID:25249034

Jovanovi?, Zoran; Spreitzer, Matjaž; Kova?, Janez; Klement, Dejan; Suvorov, Danilo

2014-10-22

264

Oxidation of the porous silicon surface under the action of a pulsed ionic beam: XPS and XANES studies  

NASA Astrophysics Data System (ADS)

The changes in the electronic structure and phase composition of porous silicon under action of pulsed ionic beams have been studied by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) using synchrotron radiation. The Si 2 p and O 1 s core photoemission spectra for different photoelectron collection angles, valence band photoemission spectra, and X-ray absorption near-edge fine structure spectrain the region of Si L 2,3 edges of the initial and irradiated samples have been analyzed. It has been found that, as a result of the irradiation, a thin oxide film consisting predominantly of higher oxide SiO2 is formed on the porous silicon surface, which increases the energy gap of the silicon oxide. Such film exhibits passivation properties preventing the degradation of the composition and properties of porous silicon in contact with the environment.

Bolotov, V. V.; Ivlev, K. E.; Korusenko, P. M.; Nesov, S. N.; Povoroznyuk, S. N.

2014-06-01

265

Hydrothermal synthesis map of bismuth titanates  

NASA Astrophysics Data System (ADS)

The hydrothermal synthesis of four bismuth titanate materials from common bismuth and titanium precursors under hydrothermal conditions is described. Reaction of NaBiO3·2H2O and anatase TiO2 in concentrated NaOH solution at 240 °C is shown to produce perovskite and sillenite phases Na0.5Bi0.5TiO3 and Bi12TiO20, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi1.43Ti2O6(OH)0.29(H2O)0.66 is formed. The use of a mixture of HNO3 and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi4Ti3O12. 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 LIII-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.

Sardar, Kripasindhu; Walton, Richard I.

2012-05-01

266

Oxidation of silicon nitride sintered with rare-earth oxide additions  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

267

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

268

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

E-print Network

necessitate incorporation of membranes in current integrated systems.2b,3 In the absence of recirculation Furthermore, avoiding explosive product mixtures and reducing efficiency losses due to gas crossover photoanodes that operate in alkaline conditions is vital to achieve an efficient solar-to-fuel system. Silicon

Javey, Ali

269

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

270

Mechanism of low temperature nitridation of silicon oxide layers by nitrogen plasma generated by low energy electron impact  

Microsoft Academic Search

Thermal silicon oxide layers formed on the Si substrate can be nitrided at low temperatures ranging between 25 and 700 °C by nitrogen plasma generated by low energy electron impact. The nitrogen concentration is high near the oxide surface, and the nitrogen atomic concentration ratio [N\\/(Si+O+N)] at the surface ranges between ~10% and ~25%, depending on the nitridation conditions. For

Toshiko Mizokuro; Kenji Yoneda; Yoshihiro Todokoro; Hikaru Kobayashi

1999-01-01

271

Fabrication of piezodriven, free-standing, all-oxide heteroepitaxial cantilevers on silicon  

NASA Astrophysics Data System (ADS)

We report on the fabrication and mechanical properties of all-oxide, free-standing, heteroepitaxial, piezoelectric, microelectromechanical systems (MEMS) on silicon, using PbZr0.52Ti0.48O3 as the key functional material. The fabrication was enabled by the development of an epitaxial lift-off strategy for the patterning of multilayer oxide heterostructures grown on Si(001), employing a high temperature stable, sacrificial oxide template mask to obtain freestanding cantilever MEMS devices after substrate etching. All cantilevers, with lengths in the range 25-325 ?m, width 50 ?m, and total thickness of 300 nm, can be actuated by an external AC-bias. For lengths 50-125 ?m, the second order bending mode formed the dominant resonance, whereas for the other lengths different or multiple modes were present.

Banerjee, N.; Houwman, E. P.; Koster, G.; Rijnders, G.

2014-09-01

272

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

273

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. PMID:23718202

2013-01-01

274

Non-wettable, Oxidation-Stable, Brightly Luminescent, Perfluorodecyl-Capped Silicon Nanocrystal Film.  

PubMed

Here we describe for the first time the synthesis of colloidally stable, brightly luminescent perfluorodecyl-capped silicon nanocrystals and compare the properties of solutions and films made from them with those of their perhydrodecyl-capped relatives. The perfluorodecyl capping group compared to the perhydrodecyl capping group yields superior hydrophobicity and much greater resistance to air oxidation, the enhanced electron-withdrawing character induces blue shifts in the wavelength of photoluminescence, and the lower-frequency carbon-fluorine stretching modes disfavor non-radiative relaxation pathways and boost the absolute photoluminescence quantum yield. Together these attributes bode well for advanced materials and biomedical applications founded upon perfluorodecyl-protected silicon nanocrystals. PMID:25350268

Qian, Chenxi; Sun, Wei; Wang, Liwei; Chen, Changlong; Liao, Kristine; Wang, Wendong; Jia, Jia; Hatton, Benjamin D; Casillas, Gilberto; Kurylowicz, Marty; Yip, Christopher M; Mastronardi, Melanie L; Ozin, Geoffrey A

2014-11-12

275

Boehmite and yttrium oxide coatings on silicon nitride from aqueous sols  

SciTech Connect

To improve the processing of silicon nitride, boehmite and yttrium oxide were coated on silicon nitride particles by an aqueous sol-gel method. It is shown that boehmite and Y{sub 2}O{sub 3} can be coated on Si{sub 3}N{sub 4} particles from aqueous solutions. However, the Y{sub 2}O{sub 3} coating is not as complete as boehmite coating. The coating of a yttria coating followed by a boehmite coating was attempted and the TEM showed a coating twice as thick as the Y{sub 2}O{sub 3} or AlOOH coating. Hydrothermal treatment of yttrium nitrate hydrous hydroxide results in the formation and growth of Y(OH){sub 3} fibers which can be calcined and transformed into Y{sub 2}O{sub 3} fibers at 500 C.

Buchta, M.; Shih, W.H. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Engineering

1997-08-01

276

Electronic passivation of silicon surfaces by thin films of atomic layer deposited gallium oxide  

NASA Astrophysics Data System (ADS)

This paper proposes the application of gallium oxide (Ga2O3) thin films to crystalline silicon solar cells. Effective passivation of n- and p-type crystalline silicon surfaces has been achieved by the application of very thin Ga2O3 films prepared by atomic layer deposition using trimethylgallium (TMGa) and ozone (O3) as the reactants. Surface recombination velocities as low as 6.1 cm/s have been recorded with films less than 4.5 nm thick. A range of deposition parameters has been explored, with growth rates of approximately 0.2 Å/cycle providing optimum passivation. The thermal activation energy for passivation of the Si-Ga2O3 interface has been found to be approximately 0.5 eV. Depassivation of the interface was observed for prolonged annealing at increased temperatures. The activation energy for depassivation was measured to be 1.9 eV.

Allen, T. G.; Cuevas, A.

2014-07-01

277

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

278

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

E-print Network

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

Mailoa, Jonathan P

2012-01-01

279

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

PubMed

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

Amoako, Kagya A; Cook, Keith E

2011-01-01

280

Thermoelectric performance of films in the bismuth-tellurium and antimony-tellurium systems  

E-print Network

Thermoelectric performance of films in the bismuth-tellurium and antimony-tellurium systems Luciana Received 10 December 2004; accepted 23 March 2005; published online 24 May 2005 Coevaporated bismuth temperature ranged from 130 to 300 °C, and glass, mica, magnesium oxide, and sapphire substrates were used

Daly, Samantha

281

Width-tunable pulse generation using four-wave mixing in bismuth based highly nonlinear fiber  

E-print Network

Width-tunable pulse generation using four-wave mixing in bismuth based highly nonlinear fiber Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China d Asahi Glass Co. Ltd., 1150 Hazawa.9-m of bismuth oxide based highly nonlinear fiber (Bi-HNLF). The width- tunable pulses are generated

Wai, Ping-kong Alexander

282

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

283

In situ transmission electron microscopy probing of native oxide and artificial layers on silicon nanoparticles for lithium ion batteries.  

PubMed

Surface modification of silicon nanoparticles via molecular layer deposition (MLD) has been recently proved to be an effective way for dramatically enhancing the cyclic performance in lithium ion batteries. However, the fundamental mechanism of how this thin layer of coating functions is not known, which is complicated by the inevitable presence of native oxide of several nanometers on the silicon nanoparticle. Using in situ TEM, we probed in detail the structural and chemical evolution of both uncoated and coated silicon particles upon cyclic lithiation/delithation. We discovered that upon initial lithiation, the native oxide layer converts to crystalline Li2O islands, which essentially increases the impedance on the particle, resulting in ineffective lithiation/delithiation and therefore low Coulombic efficiency. In contrast, the alucone MLD-coated particles show extremely fast, thorough, and highly reversible lithiation behaviors, which are clarified to be associated with the mechanical flexibility and fast Li(+)/e(-) conductivity of the alucone coating. Surprisingly, the alucone MLD coating process chemically changes the silicon surface, essentially removing the native oxide layer, and therefore mitigates side reactions and detrimental effects of the native oxide. This study provides a vivid picture of how the MLD coating works to enhance the Coulombic efficiency, preserves capacity, and clarifies the role of the native oxide on silicon nanoparticles during cyclic lithiation and delithiation. More broadly, this work also demonstrates that the effect of the subtle chemical modification of the surface during the coating process may be of equal importance to the coating layer itself. PMID:25347792

He, Yang; Piper, Daniela Molina; Gu, Meng; Travis, Jonathan J; George, Steven M; Lee, Se-Hee; Genc, Arda; Pullan, Lee; Liu, Jun; Mao, Scott X; Zhang, Ji-Guang; Ban, Chunmei; Wang, Chongmin

2014-11-25

284

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

285

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

286

Performance and characteristics of double layer porous silicon oxide resistance random access memory  

NASA Astrophysics Data System (ADS)

A bilayer resistive switching memory device with an inserted porous silicon oxide layer is investigated in this letter. Compared with single Zr:SiOx layer structure, Zr:SiOx/porous SiOx structure outperforms from various aspects, including low operating voltages, tighter distributions of set voltage, higher stability of both low resistance state and high resistance state, and satisfactory endurance characteristics. Electric field simulation by comsolTM Multiphysics is applied, which corroborates that intensive electric field around the pore in porous SiOx layer guides the conduction of electrons. The constraint of conduction path leads to better stabilization and prominent performance of bilayer resistive switching devices.

Tsai, Tsung-Ming; Chang, Kuan-Chang; Zhang, Rui; Chang, Ting-Chang; Lou, J. C.; Chen, Jung-Hui; Young, Tai-Fa; Tseng, Bae-Heng; Shih, Chih-Cheng; Pan, Yin-Chih; Chen, Min-Chen; Pan, Jhih-Hong; Syu, Yong-En; Sze, Simon M.

2013-06-01

287

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

SciTech Connect

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

Yokota, S.H.

1992-12-01

288

Single hole transport in a silicon metal-oxide-semiconductor quantum dot  

NASA Astrophysics Data System (ADS)

We describe a planar silicon metal-oxide-semiconductor (MOS) based single hole transistor, which is compatible with conventional Si complementary MOS fabrication. A multi-layer gate design gives independent control of the carrier density in the dot and reservoirs. Clear Coulomb blockade oscillations are observed, and source-drain biasing measurements show that it is possible to deplete the dot down to the few hole regime, with excited states clearly visible. The architecture is sufficiently versatile that a second hole dot could be induced adjacent to the first one.

Li, R.; Hudson, F. E.; Dzurak, A. S.; Hamilton, A. R.

2013-10-01

289

Ultrasensitive food toxin biosensor using frequency based signals of silicon oxide nanoporous structure  

NASA Astrophysics Data System (ADS)

We report an electrochemically fabricated silicon oxide nanoporous structure for ultrasensitive detection of AfB1 in food by shift in peak frequency corresponding to maximum sensitivity. It has been observed that the impedance sensitivity changes from 19% to 40% (which is only twice) where as the peak frequency shifts from 500 Hz to 50 kHz, for a change in concentration from 1 fg/ml to 1 pg/ml. This has been attributed to the combined effect of the significant pore narrowing with increasing AfB1 concentration and the opposing nature of impedance change within the nanopores and the conducting substrate immediately below the nanoporous layer.

Ghosh, H.; RoyChaudhuri, C.

2013-06-01

290

Chemical Etching of Zinc Oxide for Thin-Film Silicon Solar Cells  

PubMed Central

Abstract Chemical etching is widely applied to texture the surface of sputter-deposited zinc oxide for light scattering in thin-film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and etching agent. All grain boundaries are prone to be etched to a certain threshold, that is defined by the deposition conditions and etching solution. Additionally, several approaches to modify the etching behavior through special preparation and etching steps are provided. PMID:22162035

Hüpkes, Jürgen; Owen, Jorj I; Pust, Sascha E; Bunte, Eerke

2012-01-01

291

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

2007-05-01

292

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

293

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

294

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

295

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

NASA Astrophysics Data System (ADS)

Silicon dioxide (SiO2) films formed by chemical vapor deposition (CVD) were treated with oxygen radical oxidation using Ar/O2 plasma excited by microwave. The mass density depth profiles, carrier trap densities, and current-voltage characteristics of the radical-oxidized CVD-SiO2 films were investigated. The mass density depth profiles were estimated with x ray reflectivity measurement using synchrotron radiation of SPring-8. The carrier trap densities were estimated with x ray photoelectron spectroscopy time-dependent measurement. The mass densities of the radical-oxidized CVD-SiO2 films were increased near the SiO2 surface. The densities of the carrier trap centers in these films were decreased. The leakage currents of the metal-oxide-semiconductor capacitors fabricated by using these films were reduced. It is probable that the insulation properties of the CVD-SiO2 film are improved by the increase in the mass density and the decrease in the carrier trap density caused by the restoration of the Si-O network with the radical oxidation.

Kawase, Kazumasa; Teramoto, Akinobu; Umeda, Hiroshi; Suwa, Tomoyuki; Uehara, Yasushi; Hattori, Takeo; Ohmi, Tadahiro

2012-02-01

296

Crystallographic plane-orientation dependent atomic force microscopy-based local oxidation of silicon carbide  

PubMed Central

The effect of crystalline plane orientations of Silicon carbide (SiC) (a-, m-, and c-planes) on the local oxidation on 4H-SiC using atomic force microscopy (AFM) was investigated. It has been found that the AFM-based local oxidation (AFM-LO) rate on SiC is closely correlated to the atomic planar density values of different crystalline planes (a-plane, 7.45 cm-2; c-plane, 12.17 cm-2; and m-plane, 6.44 cm-2). Specifically, at room temperature and under about 40% humidity with a scan speed of 0.5 ?m/s, the height of oxides on a- and m-planes 4H-SiC is 6.5 and 13 nm, respectively, whereas the height of oxides on the c-plane increased up to 30 nm. In addition, the results of AFM-LO with thermally grown oxides on the different plane orientations in SiC are compared. PMID:21711752

2011-01-01

297

Crystallographic plane-orientation dependent atomic force microscopy-based local oxidation of silicon carbide.  

PubMed

The effect of crystalline plane orientations of Silicon carbide (SiC) (a-, m-, and c-planes) on the local oxidation on 4H-SiC using atomic force microscopy (AFM) was investigated. It has been found that the AFM-based local oxidation (AFM-LO) rate on SiC is closely correlated to the atomic planar density values of different crystalline planes (a-plane, 7.45 cm-2; c-plane, 12.17 cm-2; and m-plane, 6.44 cm-2). Specifically, at room temperature and under about 40% humidity with a scan speed of 0.5 ?m/s, the height of oxides on a- and m-planes 4H-SiC is 6.5 and 13 nm, respectively, whereas the height of oxides on the c-plane increased up to 30 nm. In addition, the results of AFM-LO with thermally grown oxides on the different plane orientations in SiC are compared. PMID:21711752

Ahn, Jung-Joon; Jo, Yeong-Deuk; Kim, Sang-Cheol; Lee, Ji-Hoon; Koo, Sang-Mo

2011-01-01

298

Indium-tin-oxide nanowhiskers crystalline silicon photovoltaics combining micro- and nano-scale surface textures  

NASA Astrophysics Data System (ADS)

In this work, we present a solution that employs combined micro- and nano-scale surface textures to increase light harvesting in the near infrared for crystalline silicon photovoltaics, and discuss the associated antireflection and scattering mechanisms. The combined surface textures are achieved by uniformly depositing a layer of indium-tin-oxide nanowhiskers on passivated, micro-grooved silicon solar cells using electron-beam evaporation. The nanowhiskers facilitate optical transmission in the near-infrared, which is optically equivalent to a stack of two dielectric thin-films with step- and graded- refractive index profiles. The ITO nanowhiskers provide broadband anti-reflective properties (R<5%) in the wavelength range of 350-1100nm. In comparison with conventional Si solar cell, the combined surface texture solar cell shows higher external quantum efficiency (EQE) in the range of 700-1100nm. Moreover, the ITO nano-whisker coating Si solar cell shows a high total efficiency increase of 1.1% (from 16.08% to17.18%). Furthermore, the nano-whiskers also provide strong forward scattering for ultraviolet and visible light, favorable in thin-wafer silicon photovoltaics to increase the optical absorption path.

Chang, C. H.; Hsu, M. H.; Chang, W. L.; Sun, W. C.; Yu, Peichen

2011-02-01

299

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

SciTech Connect

An improved charge separation technique for metal-oxide-silicon (MOS) capacitors is presented which accounts for the deactivation of substrate dopants by hydrogen at elevated irradiation temperatures or small irradiation biases. Using high-frequency capacitance-voltage measurements, radiation-induced inversion voltage shifts are separated into components due to oxide trapped charge, interface traps, and deactivated dopants, where the latter is computed from a reduction in Si capacitance. In the limit of no radiation-induced dopant deactivation, this approach reduces to the standard midgap charge separation technique used widely for the analysis of room-temperature irradiations. The technique is demonstrated on a p-type MOS capacitor irradiated with {sup 60}Co {gamma} rays at 100 degree sign C and zero bias, where the dopant deactivation is significant.(c) 2000 American Institute of Physics.

Witczak, Steven C. [Sandia National Laboratories, P.O. Box 5800, MS-1083, Albuquerque, New Mexico 87185-1083 (United States)] [Sandia National Laboratories, P.O. Box 5800, MS-1083, Albuquerque, New Mexico 87185-1083 (United States); Winokur, Peter S. [Sandia National Laboratories, P.O. Box 5800, MS-1083, Albuquerque, New Mexico 87185-1083 (United States)] [Sandia National Laboratories, P.O. Box 5800, MS-1083, Albuquerque, New Mexico 87185-1083 (United States); Lacoe, Ronald C. [The Aerospace Corporation, P.O. Box 92957, M2-244, Los Angeles, California 90009-2957 (United States)] [The Aerospace Corporation, P.O. Box 92957, M2-244, Los Angeles, California 90009-2957 (United States); Mayer, Donald C. [The Aerospace Corporation, P.O. Box 92957, M2-244, Los Angeles, California 90009-2957 (United States)] [The Aerospace Corporation, P.O. Box 92957, M2-244, Los Angeles, California 90009-2957 (United States)

2000-06-01

300

Gadolinium oxide coated fully depleted silicon-on-insulator transistors for thermal neutron dosimetry  

NASA Astrophysics Data System (ADS)

Fully depleted silicon-on-insulator transistors coated with gadolinium oxide are shown to be effective thermal neutron dosimeters. The theoretical neutron detection efficiency is calculated to be higher for Gd2O3 than for other practical converter materials. Proof-of-concept dosimeter devices were fabricated and tested during thermal neutron irradiation. The transistor current changes linearly with neutron dose, consistent with increasing positive charge in the SOI buried oxide layer generated by ionization from high energy 157Gd(n,?)158Gd conversion electrons. The measured neutron sensitivity is approximately 1/6 the maximum theoretical value, possibly due to electron-hole recombination or conversion electron loss in interconnect wiring above the transistors.

Vitale, Steven A.; Gouker, Pascale M.

2013-09-01

301

Self-assisted GaAs nanowires with selectable number density on Silicon without oxide layer  

NASA Astrophysics Data System (ADS)

We present the growth of self-assisted GaAs nanowires (NWs) with selectable number density on bare Si(1?1?1), not covered by the silicon oxide. We determine the number density of the NWs by initially self-assembling GaAs islands on whose top a single NW is nucleated. The number density of the initial GaAs base islands can be tuned by droplet epitaxy and the same degree of control is then transferred to the NWs. This procedure is completely performed during a single growth in an ultra-high vacuum environment and requires neither an oxide layer covering the substrate, nor any pre-patterning technique.

Bietti, S.; Somaschini, C.; Frigeri, C.; Fedorov, A.; Esposito, L.; Geelhaar, L.; Sanguinetti, S.

2014-10-01

302

The fabrication of highly ordered block copolymer micellar arrays: control of the separation distances of silicon oxide dots  

NASA Astrophysics Data System (ADS)

We demonstrate the fabrication of highly ordered silicon oxide dotted arrays prepared from polydimethylsiloxane (PDMS) filled nanoporous block copolymer (BCP) films and the preparation of nanoporous, flexible Teflon or polyimide films. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) films were annealed in toluene vapor to enhance the lateral order of micellar arrays and were subsequently immersed in alcohol to produce nano-sized pores, which can be used as templates for filling a thin layer of PDMS. When a thin layer of PDMS was spin-coated onto nanoporous BCP films and thermally annealed at a certain temperature, the PDMS was drawn into the pores by capillary action. PDMS filled BCP templates were exposed to oxygen plasma environments in order to fabricate silicon oxide dotted arrays. By addition of PS homopolymer to PS-b-P2VP copolymer, the separation distances of micellar arrays were tuned. As-prepared silicon oxide dotted arrays were used as a hard master for fabricating nanoporous Teflon or polyimide films by spin-coating polymer precursor solutions onto silicon patterns and peeling off. This simple process enables us to fabricate highly ordered nanoporous BCP templates, silicon oxide dots, and flexible nanoporous polymer patterns with feature size of sub-20 nm over 5 cm × 5 cm.

Yoo, Hana; Park, Soojin

2010-06-01

303

Deuterium Process to Improve Gate Oxide Integrity in Metal-Oxide-Silicon (MOS) Structure  

NASA Astrophysics Data System (ADS)

We studied alternative process that deuterium can be delivered to the location we want by an implant process. In our processed MOS structure, deuterium ions were located over the top of gate oxide. A short anneal at forming gas was performed to remove the D-implantation damage. We have observed that deuterium ions at the gate oxide can definitely improve device's gate dielectric characteristics. Also, we have observed that the energy and dose of ion implantation need to be optimized, not to disturb the impurity distribution near channel area.

Seo, Young-Ho; Do, Seung-Woo; Lee, Yong-Hyun; Lee, Jae-Sung

2011-12-01

304

Improved gate oxide integrity of strained Si n-channel metal oxide silicon field effect transistors using thin virtual substrates  

NASA Astrophysics Data System (ADS)

This work presents a detailed study of ultrathin gate oxide integrity in strained Si metal oxide silicon field effect transistors (MOSFETs) fabricated on thin virtual substrates aimed at reducing device self-heating. The gate oxide quality and reliability of the devices are compared to those of simultaneously processed Si control devices and conventional thick virtual substrate devices that have the same Ge content (20%), strained Si channel thickness, and channel strain. The thin virtual substrates offer the same mobility enhancement as the thick virtual substrates (˜100% compared to universal mobility data) and are effective at reducing device self-heating. Up to 90% improvement in gate leakage current is demonstrated for the strained Si n-channel MOSFETs compared to that for the bulk Si controls. The lower leakage arises from the increased electron affinity in tensile strained Si and is significant due to the sizeable strain generated by using wafer-level stressors. The strain-induced leakage reductions also lead to major improvements in stress-induced leakage current (SILC) and oxide reliability. The lower leakage current of the thin and thick virtual substrate devices compares well to theoretical estimates based on the Wentzel-Kramers-Brillouin approximation. Breakdown characteristics also differ considerably between the devices, with the strained Si devices exhibiting a one order of magnitude increase in time to hard breakdown (THBD) compared to the Si control devices following high-field stressing at 17 MV cm-1. The strained Si devices are exempted from soft breakdown. Experimental based analytical leakage modeling has been carried out across the field range for the first time in thin oxides and demonstrates that Poole-Frenkel (PF) emissions followed by Fowler-Nordheim tunneling dominate gate leakage current at low fields in all of the devices. This contrasts to the frequently reported assumption that direct tunneling dominates gate leakage in ultrathin oxides. We also show that PF emissions are reduced in strained Si devices compared to bulk Si devices. The gate leakage, interface trap density, bulk oxide traps, breakdown characteristics, and SILC are further improved in the thin virtual substrate devices compared to the thick virtual substrate devices. The difference is attributed to surface roughness. The thick virtual substrates exhibit characteristic cross-hatching morphology, whereas the thin virtual substrates do not since they relax primarily through point defects rather than misfit dislocations. Virtual substrate growth techniques that minimize surface roughness will, therefore, benefit all state-of-the-art devices featuring strained Si, strained Si-on-insulator, and strained Ge that are generated by using relaxed SiGe platforms.

Yan, L.; Olsen, S. H.; Escobedo-Cousin, E.; O'Neill, A. G.

2008-05-01

305

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

306

Optical and structural characterization of thermal oxidation effects of erbium thin films deposited by electron beam on silicon  

NASA Astrophysics Data System (ADS)

Thermal oxidation effects on the structural, compositional, and optical properties of erbium films deposited on silicon via electron beam evaporation were analyzed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and spectroscopic ellipsometry. A gradual rise in oxidation temperature from 700 to 900 °C resulted in a transition from ErO- to Er2O3-rich phase. Additional increase in oxidation temperature above 1000°C led to the formation of erbium silicate due to further oxygen incorporation, as well as silicon out-diffusion from the substrate. A silicon oxide interfacial layer was also detected, with its thickness increasing with higher oxidation temperature. Additionally, film refractive index decreased, while its Tauc bandgap value increased from ˜5.2 eV to ˜6.4 eV, as the oxidation temperature was raised from 700 °C to above 900 °C. These transformations were accompanied by the appearance of an intense and broad absorption band below the optical gap. Thermal oxidation effects are discussed in the context of film structural characteristics and defect states.

Kamineni, Himani S.; Kamineni, Vimal K.; Moore, Richard L.; Gallis, Spyros; Diebold, Alain C.; Huang, Mengbing; Kaloyeros, Alain E.

2012-01-01

307

Optical and structural characterization of thermal oxidation effects of erbium thin films deposited by electron beam on silicon  

SciTech Connect

Thermal oxidation effects on the structural, compositional, and optical properties of erbium films deposited on silicon via electron beam evaporation were analyzed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and spectroscopic ellipsometry. A gradual rise in oxidation temperature from 700 to 900 deg. C resulted in a transition from ErO- to Er{sub 2}O{sub 3}-rich phase. Additional increase in oxidation temperature above 1000 deg. C led to the formation of erbium silicate due to further oxygen incorporation, as well as silicon out-diffusion from the substrate. A silicon oxide interfacial layer was also detected, with its thickness increasing with higher oxidation temperature. Additionally, film refractive index decreased, while its Tauc bandgap value increased from {approx}5.2 eV to {approx}6.4 eV, as the oxidation temperature was raised from 700 deg. C to above 900 deg. C. These transformations were accompanied by the appearance of an intense and broad absorption band below the optical gap. Thermal oxidation effects are discussed in the context of film structural characteristics and defect states.

Kamineni, Himani S.; Kamineni, Vimal K.; Moore, Richard L.; Gallis, Spyros; Diebold, Alain C.; Huang Mengbing; Kaloyeros, Alain E. [College of Nanoscale Science and Engineering, University at Albany, 255 Fuller Road, Albany, New York, 12203 (United States)

2012-01-01

308

Reliability and Memory Characteristics of Sequential Laterally Solidified Low Temperature Polycrystalline Silicon Thin Film Transistors with an Oxide-Nitride-Oxide Stack Gate Dielectric  

NASA Astrophysics Data System (ADS)

In this work, low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs) with sequential lateral solidification (SLS) laser annealing process were fabricated. The grain boundaries (GB) can be well-controlled to avoid the channel area, so that the device mobility is created enhanced. The device performance and reliability between oxide-nitride-oxide (ONO) stacked gate dielectric devices and conventional SiO2 devices have been measured and analyzed under AC stress conditions. These results indicate that LTPS TFTs with ONO structure exhibit better reliability characteristics than conventional ones. A TFT metal-oxide-nitride-oxide-silicon (MONOS) memory device is also investigated. This MONOS device is a promising embedded non-volatile memory candidate to reduce power consumption for mobile applications.

Hsieh, Szu?I; Chen, Hung?Tse; Chen, Yu?Cheng; Chen, Chi?Lin; Lin, Jia?Xing; King, Ya?Chin

2006-04-01

309

The Exotic Barium Bismuthates  

NASA Astrophysics Data System (ADS)

We review the remarkable properties, including superconductivity, charge-density-wave ordering and metal-insulator transitions, of lead- and potassium-doped barium bismuthate. We will discuss some of the early theoretical studies of these systems. Our recent theoretical work, on the negative-U, extended-Hubbard model for these systems, will also be described. Both the large- and intermediate-U regimes of this model were examined, using mean-field and random-phase approximations, particularly with a view to fitting various experimental properties of these bismuthates. On the basis of our studies, we point out possibilities for exotic physics in these systems. We also emphasize the different consequences of electronic and phonon-mediated mechanisms for the negative U. We show that, for an electronic mechanism, the semiconducting phases of these bismuthates must be unique, with their transport properties dominated by charge ±2e Cooperon bound states. This can explain the observed difference between the optical and transport gaps. We propose other experimental tests for this novel mechanism of charge transport and comment on the effects of disorder.

Taraphder, A.; Pandit, Rahul; Krishnamurthy, H. R.; Ramakrishnan, T. V.

310

986 IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 17, NO. 5, MAY 2005 Wavelength-Switchable La-Codoped Bismuth-Based  

E-print Network

polarization controller, and a 0.85-m-long La-codoped bis- muth-based Bi-EDF. La-codoped bismuth oxide glass ppm can be doped in Bismuth-based glass without significant ion quenching effect [6], [7-Codoped Bismuth-Based Erbium-Doped Fiber Ring Laser H. L. Liu, H. Y. Tam, Senior Member, IEEE, W. H. Chung, P. K

Wai, Ping-kong Alexander

311

Trap assisted leakage current conduction in thin silicon oxynitride films grown by rapid thermal oxidation combined microwave excited plasma nitridation  

Microsoft Academic Search

Thin films of silicon oxynitride (SiON) were grown on Si substrates by nitriding rapid thermally grown SiO2 layers in a microwave-excited nitrogen plasma and by subsequent re-oxidation. The enhanced leakage current in SiON at oxide fields 5–7 MV\\/cm is due to a trap assisted tunneling current. Trap assisted tunneling current analysis indicated a trap level of 1 eV below the

Rohana Perera; Akihiro Ikeda; Reiji Hattori; Yukinori Kuroki

2003-01-01

312

Simultaneous extraction of the silicon film and front oxide thicknesses on fully depleted SOI nMOSFETs  

NASA Astrophysics Data System (ADS)

This work presents a new method to extract the silicon film and front oxide thickness on fully depleted silicon-on-insulator nMOSFETs. The proposed method exploits the influence of the front/back gate voltages on the back/front channel current regime. To extract the silicon film thickness, the drain current curve is measured as a function of the back gate voltage VGB with the front interface inverted. When the back interface condition changes due to the back gate voltage, kinks occur in the front drain current for specific VGB biases and these are used by the method. Similarly, the back drain current as a function of the front gate voltage VGF with the back interface inverted shows some kinks at specific VGF, which are used by the method to extract the front oxide thickness. MEDICI simulations were used to support the analysis and the method was validated experimentally.

Nicolett, A. S.; Martino, J. A.; Simoen, E.; Claeys, C.

2000-11-01

313

Ion microprobe study of the scale formed during high temperature oxidation of high silicon EN-1.4301 stainless steel  

NASA Astrophysics Data System (ADS)

A study of the oxide layer formed on the surface of high silicon (0.8%) EN-1.4301 (AISI-304) stainless steel after 125 h oxidation in air at 1273 K has been performed by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), RBS and proton microprobe. Oxidation experiments in synthetic air were performed in a thermobalance and the kinetic curve is compared to that of a standard EN-1.4301 austenitic stainless steel. These results show that the high silicon steel presents an enhanced oxidation resistance. XRD experiments show that the only crystalline species present in the scale is Cr 2O 3. Nevertheless, transversal section studies of the scale using proton microprobe show the development of a multilayered scale formed by an amorphous silicon rich layer in the scale to alloy interface and a Cr 2O 3 oxide layer in the external scale. Those results are confirmed by SEM experiments. The formation of the silica layer can be the responsible of the increase in the resistance to high temperature oxidation in this steel.

Paúl, A.; Elmrabet, S.; Alves, L. C.; da Silva, M. F.; Soares, J. C.; Odriozola, J. A.

2001-07-01

314

Plasma-activated direct bonding of diamond-on-insulator wafers to thermal oxide grown silicon wafers  

E-print Network

Plasma-activated direct bonding of diamond-on-insulator wafers to thermal oxide grown silicon microscopy, profilometer and wafer bow measurements. Plasma-activated direct bonding of DOI wafers to thermal September 2010 Keywords: Diamond-on-insulator Plasma activation Ultrananocrystalline diamond Direct bonding

Akin, Tayfun

315

ATOMIC-LAYER-DEPOSITED ALUMINUM OXIDE FOR THE SURFACE PASSIVATION OF HIGH-EFFICIENCY SILICON SOLAR CELLS  

E-print Network

ATOMIC-LAYER-DEPOSITED ALUMINUM OXIDE FOR THE SURFACE PASSIVATION OF HIGH-EFFICIENCY SILICON SOLAR- contacted rear being either passivated by atomic-layer- deposited Al2O3 or by stacks consisting-Si passivation to thermal processes. ATOMIC-LAYER-DEPOSITED Al2O3 Recently, it was shown that thin films

316

High performance multilayered nano-crystalline silicon\\/silicon-oxide light-emitting diodes on glass substrates  

Microsoft Academic Search

A low-temperature hydrogenation-assisted sequential deposition and crystallization technique is reported for the preparation of nano-scale silicon quantum dots suitable for light-emitting applications. Radio-frequency plasma-enhanced deposition was used to realize multiple layers of nano-crystalline silicon while reactive ion etching was employed to create nano-scale features. The physical characteristics of the films prepared using different plasma conditions were investigated using scanning electron

S. Darbari; M. Shahmohammadi; M. Mortazavi; S. Mohajerzadeh; Y. Abdi; M. Robertson; T. Morrison

2011-01-01

317

The location and doping effect of boron in Si nanocrystals embedded silicon oxide film  

SciTech Connect

Electrically activated doping of boron (B) atoms into the Si-nanocrystals (Si-NCs) embedded silicon oxide film is achieved by co-sputtering technique following with the annealing treatment. The evolution of the size, the shape, and the density of Si-NCs with the doping of B atoms is investigated. The observation of x-ray photoelectron spectroscopy of Si 2p and B 1s and the decrease in lattice spacing of Si (111) plane suggest that B atoms are doped into Si-NCs. The activated doping is confirmed by the Fano effect of the micro-Raman spectra for Si-NCs and the drastic decrease of the sheet resistance.

Xie, Min; Li, Dongsheng; Chen, Le; Wang, Feng; Zhu, Xiaodong; Yang, Deren [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)] [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2013-03-25

318

Patterns of discoloration and oxidation by direct and scattered fluxes on LDEF, including oxygen on silicon  

NASA Technical Reports Server (NTRS)

A number of interesting discoloration patterns are clearly evident on MOOO2-1 which resides on the three faces of the Long Duration Exposure Facility (LDEF). Most interesting is the pattern of blue oxidation on polished single crystal silicon apparently produced by scattered or direct ram oxygen atoms along the earth face. A complete explanation for the patterns has not yet been obtained. All honeycomb outgassing holes have a small discoloration ring around them that varies in color. The shadow cast by a suspended wire on the earth face surface is not easily explained by either solar photons or by ram flux. The shadows and the dark/light regions cannot be explained consistently by the process of solar ultraviolet paint-darkening modulated by ram flux oxygen bleaching of the paint.

Frederickson, A. R.; Filz, R. C.; Rich, F. J.; Sagalyn, P. L.

1992-01-01

319

Paralinear Oxidation of Silicon Nitride in a Water Vapor/Oxygen Environment  

NASA Technical Reports Server (NTRS)

Three silicon nitride materials were exposed to dry oxygen flowing at 0.44 cm/s at temperatures between 1200 and 1400 C. Reaction kinetics were measured with a continuously recording microbalance. Parabolic kinetics were observed. When the same materials were exposed to a 50% H2O - 50% O2 gas mixture flowing at 4.4 cm/s, all three types exhibited paralinear kinetics. The material is oxidized by water vapor to form solid silica. The protective silica is in turn volatilized by water vapor to form primarily gaseous Si(OH)4. Nonlinear least squares analysis and a paralinear kinetic model were used to determine both parabolic and linear rate constants from the kinetic data. Volatilization of the protective silica scale can result in accelerated consumption of Si3N4. Recession rates under conditions more representative of actual combustors are compared to the furnace data.

Fox, Dennis S.; Opila, Elizabeth J.; Nguyen, QuynhGiao; Humphrey, Donald L.; Lewton, Susan M.; Gray, Hugh R. (Technical Monitor)

2002-01-01

320

Translocation of double-strand DNA through a silicon oxide nanopore  

NASA Astrophysics Data System (ADS)

We report double-strand DNA translocation experiments using silicon oxide nanopores with a diameter of about 10 nm . By monitoring the conductance of a voltage-biased pore, we detect molecules with a length ranging from 6557 to 48 500 base pairs. We find that the molecules can pass the pore both in a straight linear fashion and in a folded state. Experiments on circular DNA further support this picture. We sort the molecular events according to their folding state and estimate the folding position. As a proof-of-principle experiment, we show that a nanopore can be used to distinguish the lengths of DNA fragments present in a mixture. These experiments pave the way for quantitative analytical techniques with solid-state nanopores.

Storm, A. J.; Chen, J. H.; Zandbergen, H. W.; Dekker, C.

2005-05-01

321

Translocation of double-strand DNA through a silicon oxide nanopore.  

PubMed

We report double-strand DNA translocation experiments using silicon oxide nanopores with a diameter of about 10 nm . By monitoring the conductance of a voltage-biased pore, we detect molecules with a length ranging from 6557 to 48 500 base pairs. We find that the molecules can pass the pore both in a straight linear fashion and in a folded state. Experiments on circular DNA further support this picture. We sort the molecular events according to their folding state and estimate the folding position. As a proof-of-principle experiment, we show that a nanopore can be used to distinguish the lengths of DNA fragments present in a mixture. These experiments pave the way for quantitative analytical techniques with solid-state nanopores. PMID:16089567

Storm, A J; Chen, J H; Zandbergen, H W; Dekker, C

2005-05-01

322

Light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst  

PubMed Central

Integrating a silicon solar cell with a recently developed cobalt-based water-splitting catalyst (Co-Pi) yields a robust, monolithic, photo-assisted anode for the solar fuels process of water splitting to O2 at neutral pH. Deposition of the Co-Pi catalyst on the Indium Tin Oxide (ITO)-passivated p-side of a np-Si junction enables the majority of the voltage generated by the solar cell to be utilized for driving the water-splitting reaction. Operation under neutral pH conditions fosters enhanced stability of the anode as compared to operation under alkaline conditions (pH 14) for which long-term stability is much more problematic. This demonstration of a simple, robust construct for photo-assisted water splitting is an important step towards the development of inexpensive direct solar-to-fuel energy conversion technologies. PMID:21646536

Pijpers, Joep J. H.; Winkler, Mark T.; Surendranath, Yogesh; Buonassisi, Tonio; Nocera, Daniel G.

2011-01-01

323

Positron annihilation study of defects and Si nanoprecipitation in sputter-deposited silicon oxide films  

NASA Astrophysics Data System (ADS)

Positron annihilation spectroscopy was conducted to study defects and Si nanoprecipitation in sputter-deposited silicon oxide films. For as-deposited SiO 0.9 and SiO 1.9 films, Doppler broadening spectra are strongly influenced by the type of paramagnetic defects ( Pb or E'). However, the disappearance of these defects after annealing at 1050 °C in a vacuum cannot account for the corresponding change of the Doppler broadening. In annealed film of SiO 1.9, positronium formation is reduced from defect-free SiO 2 because of the presence of Si precipitates; meanwhile, in annealed film of SiO 0.9 with nanocrystalline Si (nc-Si), positron annihilation with high momentum electrons is enhanced as a result of efficient positron trapping at the nc-Si surface with oxygen.

Yu, R. S.; Ito, K.; Hirata, K.; Sato, K.; Zheng, W.; Kobayashi, Y.

2003-09-01

324

Plasma surface oxidation of 316L stainless steel for improving adhesion strength of silicone rubber coating to metal substrate  

NASA Astrophysics Data System (ADS)

Stainless steel 316L is one of the most widely used materials for fabricating of biomedical devices hence, improving its surface properties is still of great interest and challenging in biomaterial sciences. Plasma oxidation, in comparison to the conventional chemical or mechanical methods, is one of the most efficient methods recently used for surface treatment of biomaterials. Here, stainless steel specimens were surface oxidized by radio-frequency plasma irradiation operating at 34 MHz under pure oxygen atmosphere. Surface chemical composition of the samples was significantly changed after plasma oxidation by appearance of the chromium and iron oxides on the plasma-oxidized surface. A wettable surface, possessing high surface energy (83.19 mN m-1), was observed after plasma oxidation. Upon completion of the surface modification process, silicone rubber was spray coated on the plasma-treated stainless steel surface. Morphology of the silicone rubber coating was investigated by scanning electron microscopy (SEM). A uniform coating was formed on the oxidized surface with no delamination at polymer-metal interface. Pull-off tests showed the lowest adhesion strength of coating to substrate (0.12 MPa) for untreated specimens and the highest (0.89 MPa) for plasma-oxidized ones.

Latifi, Afrooz; Imani, Mohammad; Khorasani, Mohammad Taghi; Daliri Joupari, Morteza

2014-11-01

325

Bismuth nitrate pentahydrate-induced novel nitration of eugenol  

PubMed Central

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

2011-01-01

326

First-principle calculations of electronic structure of bismuth ferrate and manganate with the mullite structure  

NASA Astrophysics Data System (ADS)

We applied ab initio total-energy calculation to study the electronic structure of Bi2Fe4O9 and Bi2Mn4O10 single crystals. Both crystals are orthorhombic with the centro-symmetric structure and belong to the mullite-type material. Most of bismuth-based oxides exhibit good ferroelectricity, pyroelectricity and piezoelectricity. However, little researches of electronic structure and properties have been done on the bismuth ferrate and bismuth manganate. In this study, the band structure, density of state, partial density of state and magnetic moment of both bismuth ferrate and bismuth manganate at zero Kevin were calculated. The effect of Fe and Mn atom within the structure were discussed. The phase stability of these two crystals was also examined.

Chen, Jen-Chang; Wei, Ching-Ming

2008-03-01

327

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

328

Photothermal laser processing of thin silicon nanoparticle films: on the impact of oxide formation on film morphology  

NASA Astrophysics Data System (ADS)

Photothermal laser processing of thin films of H-terminated silicon nanoparticles (Si NPs) is investigated. Ethanolic dispersions of Si NPs with an average diameter of 45 nm are spin-coated on silicon substrates yielding films with thicknesses ?500 nm. Small-area laser processing is carried out using a microfocused scanning cw-laser setup operating at a wavelength of 532 nm and a 1/e laser spot size of 1.4 ?m. In conjunction with microscopic techniques, this provides a highly reproducible and convenient approach in order to study the dependence of the resulting film morphology and composition on the experimental parameters. Processing in air results in strongly oxidized granular structures with sizes between 100 and 200 nm. The formation of these structures is dominated by surface oxidation. In particular, changing the processing parameters (i.e., laser power, writing speed, and/or the background air pressure) has little effect on the morphology. Only in vacuum at pressures <1 mbar, oxygen adsorption, and hence oxide formation, is largely suppressed. Under these conditions, irradiation at low laser powers results in mesoporous surface layers, whereas compact silicon films are formed at high laser powers. In agreement with these results, comparative experiments with films of H-terminated and surface-oxidized Si NPs reveal a strong impact of the surface oxide layer on the film morphology. Mechanistic aspects and implications for photothermal processing techniques, e.g., targeting photovoltaic and thermoelectric applications, are discussed.

Behrenberg, Dennis; Franzka, Steffen; Petermann, Nils; Wiggers, Hartmut; Hartmann, Nils

2012-03-01

329

Low temperature direct bonding mechanisms of tetraethyl orthosilicate based silicon oxide films deposited by plasma enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Bonding behaviour and surface adhesion mechanisms of tetraethyl orthosilicate silicon oxide films are investigated. Prior to the bonding, infrared absorption spectroscopy was used to assess chemical composition of the bonding layers. The incorporation of -OH groups during the deposition process and the moisture absorption is shown and a specific effect of the applied RF power is highlighted. A strong correlation is found between trapped species and the evolution of the bonded layers during subsequent thermal annealing. The first observed phenomenon is an overall hardness reduction of the film deposited at low RF power which results in an increase of local adhesion area, hence an enhancement of the bonding energy. In the meantime, in this configuration water production is promoted in the volume of the film through silanol condensation and silicon oxidation occurs at the interface between the bonding layer and the silicon bulk. As a by-product of this reaction, hydrogen is released and it migrates towards the bonding interface. As a consequence, defects appear at the bonding interface. Thanks to the use of a stop barrier at the bulk interface, silicon oxidation is prevented, defect free bonding is obtained and the described scenario is confirmed.

Sabbione, C.; Di Cioccio, L.; Vandroux, L.; Nieto, J.-P.; Rieutord, F.

2012-09-01

330

The silicon/zinc oxide interface in amorphous silicon-based thin-film solar cells: Understanding an empirically optimized contact  

NASA Astrophysics Data System (ADS)

The electronic structure of the interface between the boron-doped oxygenated amorphous silicon "window layer" (a-SiOx:H(B)) and aluminum-doped zinc oxide (ZnO:Al) was investigated using hard x-ray photoelectron spectroscopy and compared to that of the boron-doped microcrystalline silicon (?c-Si:H(B))/ZnO:Al interface. The corresponding valence band offsets have been determined to be (-2.87 ± 0.27) eV and (-3.37 ± 0.27) eV, respectively. A lower tunnel junction barrier height at the ?c-Si:H(B)/ZnO:Al interface compared to that at the a-SiOx:H(B)/ZnO:Al interface is found and linked to the higher device performances in cells where a ?c-Si:H(B) buffer between the a-Si:H p-i-n absorber stack and the ZnO:Al contact is employed.

Gerlach, D.; Wilks, R. G.; Wippler, D.; Wimmer, M.; Lozac'h, M.; Félix, R.; Mück, A.; Meier, M.; Ueda, S.; Yoshikawa, H.; Gorgoi, M.; Lips, K.; Rech, B.; Sumiya, M.; Hüpkes, J.; Kobayashi, K.; Bär, M.

2013-07-01

331

Nickel Nanocrystals Embedded in Metal-Alumina-Nitride-Oxide-Silicon Type Low-Temperature Polycrystalline-Silicon Thin-Film Transistor for Low-Voltage Nonvolatile Memory Application  

NASA Astrophysics Data System (ADS)

In this work, a nickel nanocrystal (Ni-NC) assisted metal-alumina-nitride-oxide-silicon (MANOS) thin-film transistor (TFT) nonvolatile memory (NVM) was fabricated by a standard low temperature polycrystalline silicon (LTPS) TFT process. The size range and density of Ni-NCs were approximately 5-13 nm and 5 ×1011 cm-2, respectively. The programming/erasing (P/E) voltages are decreased down to -10 and +8 V, respectively, by the Fowler-Nordheim tunneling mechanism from gate injection. In this P/E voltage condition, a large memory window (˜4.2 V) was observed by current-voltage measurement. Then, the speed and voltages of P/E were measured and discussed completely. The data retention of the Ni-NC assisted MANOS-LTPS-TFT-NVM is extracted to be 1.62 V of memory window after 104 s.

Tai-Jui Wang, Terry; Liu, Yu-Cheng; Wu, Chien-Hung; Lu, Tien-Lin; Hsieh, Ing-Jar; Kuo, Cheng-Tzu

2011-06-01

332

Nickel Nanocrystals Embedded in Metal--Alumina--Nitride--Oxide--Silicon Type Low-Temperature Polycrystalline-Silicon Thin-Film Transistor for Low-Voltage Nonvolatile Memory Application  

NASA Astrophysics Data System (ADS)

In this work, a nickel nanocrystal (Ni-NC) assisted metal--alumina--nitride--oxide--silicon (MANOS) thin-film transistor (TFT) nonvolatile memory (NVM) was fabricated by a standard low temperature polycrystalline silicon (LTPS) TFT process. The size range and density of Ni-NCs were approximately 5--13 nm and 5 × 1011 cm-2, respectively. The programming/erasing (P/E) voltages are decreased down to -10 and +8 V, respectively, by the Fowler--Nordheim tunneling mechanism from gate injection. In this P/E voltage condition, a large memory window (˜4.2 V) was observed by current--voltage measurement. Then, the speed and voltages of P/E were measured and discussed completely. The data retention of the Ni-NC assisted MANOS-LTPS-TFT-NVM is extracted to be 1.62 V of memory window after 104 s.

Wang, Terry Tai-Jui; Liu, Yu-Cheng; Wu, Chien-Hung; Lu, Tien-Lin; Hsieh, Ing-Jar; Kuo, Cheng-Tzu

2011-06-01

333

On the partial oxidation of propane and propylene on mixed metal oxide catalysts  

Microsoft Academic Search

The present review analyses the literature data reported on the partial oxidation of propane to organic compounds (acrolein, acrylic acid and acrylonitrile) over mixed metal oxides, mainly magnesium vanadates, vanadia bismuth molybdates and vanadia antimony. The data were compared to those reported on the partial oxidation of propylene over bismuth molybdate and antimony—tin multicomponent oxides and over cuprous simple oxide.

M. M. Bettahar; G. Costentin; L. Savary; J. C. Lavalley

1996-01-01

334

Room temperature operation of Er-doped silicon-rich oxide microcavities supporting high-Q whispering-gallery modes  

NASA Astrophysics Data System (ADS)

In the past few years, many studies have been carried out to use the ability of light to transport information into silicon-based integrated photonic circuits. The realization of an efficient silicon-based light source is therefore necessary but however challenging. Lasing cannot be easily achieved from silicon emission because of its indirect bandgap. Therefore, one solution proposed is to use other efficient emitters, like rare earth, into silicon or Silicon On Insulator based microcavities. Silica microdisk has been demonstrated to support high-Q whispering-gallery modes, and can be upgraded to ultra-high-Q toroidal microcavities by a CO2 laser melting process. Microdisk high Q-factor balances the low gain generally obtained from the active medium. Thus, those microcavities may be good candidates for silicon-based laser. In this paper, the fabrication and room temperature operation of silica microdisk associated with Er-doped silicon rich oxide is presented. Er atoms are excited at the 351 nm wavelength via the silicon clusters, giving to the material a high photonic capture section, and therefore a good photoluminescence efficiency. We demonstrate efficient coupling of erbium atoms to high-Q whispering-gallery modes. The photoluminescence spectrum is then theoretically treated. The WGM resonances are thus identified. We also discuss the contribution of the spot excitation and the weak coupling to the higher radial order modes. Finally, the polarization dependence of the observed modes is investigated, and the experimental results are compared to our analytical model of disk-shape cavities. Those results give us to think that an integrated laser should be soon achieved.

Phan Huy, Kien; Verbert, Jeremy; Orucevic, Fedja; Mazen, Frederic; Noe, Pierre; Hare, Jean; Lefevre-Seguin, Valerie; Morand, Alain; Benech, Pierre; Gerard, Jean-Michel; Hadji, Emmanuel

2005-08-01

335

Stress control of plasma enhanced chemical vapor deposited silicon oxide film from tetraethoxysilane  

NASA Astrophysics Data System (ADS)

Thin silicon dioxide films have been studied as a function of deposition parameters and annealing temperatures. Films were deposited by tetraethoxysilane (TEOS) dual-frequency plasma enhanced chemical vapor deposition with different time interval fractions of high-frequency and low-frequency plasma depositions. The samples were subsequently annealed up to 930 °C to investigate their stress behavior. Films that were deposited in high-frequency dominated plasma were found to have tensile residual stress after annealing at temperatures higher than 800 °C. The residual stress can be controlled to slightly tensile by changing the annealing temperature. High tensile stress was observed during the annealing of high-frequency plasma-deposited films, leading to film cracks that limit the film thickness, as predicted by the strain energy release rate equation. Thick films without cracks were obtained by iterating deposition and annealing to stack multiple layers. A series of wet cleaning experiments were conducted, and we discovered that water absorption in high-frequency plasma-deposited films causes the residual stress to decrease. A ?40 nm thick low-frequency deposited oxide cap is sufficient to prevent water from diffusing through the film. Large-area free-standing tensile stressed oxide membranes without risk of buckling were successfully fabricated.

Guan, D.; Bruccoleri, A. R.; Heilmann, R. K.; Schattenburg, M. L.

2014-02-01

336

Surface reactions of (sub)monolayers of small organic species on oxidized silicon  

NASA Astrophysics Data System (ADS)

The preparation of (sub)monolayers of small and short-chain organic molecules on oxide-covered silicon is described. The molecular end groups and their chemical reactions were characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, spectroscopic ellipsometry (IR-UV), laserinduced desorption of monolayers (LIDOM), X-ray photoelectron spectroscopy (XPS), and contact-angle experiments. Surface species were identified and their reactions were monitored by FTIR analysis of characteristic vibrational modes. This includes bottom-up synthesis of siloxane chains, diverse reactions of double bonds, and specific molecular transformations such as the Diels-Alder reaction. Layer thicknesses could be estimated with a sensitivity of ~0.02 nm and accuracy of ~0.05 nm by oxidation of the hydrocarbons. This was achieved by in situ real-time detection of the corresponding thickness changes by spectroscopic ellipsometry. From time-of-flight (TOF) experiments, which provided the desorption temperature and mass of the emitted species, the thermal stability, chemical transformation, and fragmentation pattern of chemisorbed species could be extracted. To analyze the hydrophilic or hydrophobic nature of functionalized surfaces the surface energy and wettability were determined.

Salingue, N.; Lingenfelser, D.; Prunici, P.; Hess, P.

2009-05-01

337

Low-loss photonic wires defined by local oxidation of silicon (LOCOS)  

NASA Astrophysics Data System (ADS)

We demonstrate low-loss photonic wire waveguides, in both the straight and bent waveguide configurations, fabricated by the LOCal Oxidation of Silicon (LOCOS) process, using the standard optical lithography. The oxidation in the LOCOS process produces waveguides in submicron dimensions with ultra-smooth sidewalls. The Full-Width Half- Maximum (FWHM) of the fabricated LOCOS wire waveguide is approximately 650 nm and the height is 280 nm. We used the cut-back method to measure the propagation loss of the TE (x-polarized) mode. The average propagation loss measured by the cut-back method was 8.78 dB/cm, while the minimum measured propagation loss achieved was 7.18 dB/cm for simple straight waveguides. The propagation loss is expected to be lower, as we include the scattering loss in the measurements. The measured bending loss of the LOCOS wire waveguide with a bending radius of 5 um is as low as 0.0089 dB/90° bend for the TE mode. To the best of knowledge, this is the first direct measurement in propagation loss and bending loss for LOCOS wire waveguides.

Xiong, Yule; Ibrahim, Marc; Ye, Winnie N.

2012-01-01

338

Transparent conducting oxide contacts and textured metal back reflectors for thin film silicon solar cells  

NASA Astrophysics Data System (ADS)

With the growing population and the increasing environmental problems of the 'common' fossil and nuclear energy production, the need for clean and sustainable energy sources is evident. Solar energy conversion, such as in photovoltaic (PV) systems, can play a major role in the urgently needed energy transition in electricity production. At the present time PV module production is dominated by the crystalline wafer technology. Thin film silicon technology is an alternative solar energy technology that operates at lower efficiencies, however, it has several significant advantages, such as the possibility of deposition on cheap (flexible) substrates and the much smaller silicon material consumption. Because of the small thickness of the solar cells, light trapping schemes are needed in order to obtain enough light absorption and current generation. This thesis describes the research on thin film silicon solar cells with the focus on the optimization of the transparent conducting oxide (TCO) layers and textured metal Ag substrate layers for the use as enhanced light scattering back reflectors in n-i-p type of solar cells. First we analyzed ZnO:Al (TCO) layers deposited in an radio frequent (rf) magnetron deposition system equipped with a 7 inch target. We have focused on the improvement of the electrical properties without sacrificing the optical properties by increasing the mobility and decreasing the grain boundary density. Furthermore, we described some of the effects on light trapping of ZnO:Al enhanced back reflectors. The described effects are able to explain the observed experimental data. Furthermore, we present a relation between the surface morphology of the Ag back contact and the current enhancement in microcrystalline (muc-Si:H) solar cells. We show the importance of the lateral feature sizes of the Ag surface on the light scattering and introduce a method to characterize the quality of the back reflector by combining the vertical and lateral feature sizes at this surface. Additionally, we show that we can control the lateral feature sizes and obtain an optimized roughness for light scattering. With this new knowledge we were able to indicate the influence of the surface plasmon absorption of the textured Ag layers on the current enhancement and recognize this effect as one of the limiting factors to the current increase in thin film solar cells. Finally we present the dark and light current voltage (J-V) parameters of muc-Si:H solar cells as a function of the rms roughness of the substrate. We show that increased roughness can result in an increased defect density of the absorbing silicon layer (i layer), which limits the current collection in the solar cell. The presented research gives better understanding of the effect of TCOs and textured interfaces on light trapping and current enhancement in thin film silicon solar cells. The thesis explains some fundamental insights in light scattering and reveals some material and morphology features that are dominantly limiting the current generation in muc-Si:H solar cells deposited on light scattering back reflectors. Furthermore, it presents a method to obtain optimized back scattering contacts at deposition temperatures below 300 oC, which opens the possibility for the use of heat resistant plastic substrates. We improved the muc-Si:H solar cell efficiency with flat back reflectors from 4.5 % and 14.6 mA/cm2 to 8.5 % and 23.4 mA/cm2 with the use of optimized back reflectors.

Franken, R. H.-J.

2006-09-01

339

Electrosurface Properties of Hydr(oxides) and Oxide Nanostructures in 1 : 1 Electrolyte Solutions: 1. Adsorption Characteristics of Boehmite, Goethite, and Silicon Dioxide  

Microsoft Academic Search

The adsorption of potential-determining ions on aluminum and iron hydroxides and silicon dioxide was measured in KCl and NaCl background solutions. It was shown that dependences of the adsorption on pH and the concentration of a background 1 : 1 electrolyte (NaCl) have the shape characteristic of oxide surfaces; the of values pHPZCwere determined. Results of adsorption measurements were used

A. V. Klebanov; N. F. Bogdanova; L. E. Ermakova; M. P. Sidorova; M. G. Osmolovskii

2001-01-01

340

On the photoluminescence of as-deposited Tb-doped silicon oxides and oxynitrides fabricated by ECR-PECVD  

NASA Astrophysics Data System (ADS)

In-situ doping of Tb3+ ions in silicon oxides and oxynitrides deposited by electron-cyclotron-resonance plasma enhanced chemical-vapour (ECR-PECVD) has been performed. Oxygen and nitrogen gas flow rates were changed to produce a gradual substitution of oxygen by nitrogen in the host matrix. Bright green luminescence from as-deposited layers is observed by the naked eye under daylight conditions. Tbdoped nitrogen-rich samples showed a considerable photoluminescence (PL) enhancement compared to Tb-doped silicon oxides. An optimum layer composition for efficient Tb3+ excitation under non-resonant optical pumping is obtained. The combination of a low temperature treatment with bright luminescence could be instrumental for the development of light emitting devices in other platforms with more restrictive temperature requirements.

Ramírez, J. M.; Wojcik, J.; Berencén, Y.; Mascher, P.; Garrido, B.

2014-05-01

341

Corrosion by liquid lead and lead-bismuth: experimental results review and analysis  

SciTech Connect

Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews corrosion by liquid lead and lead bismuth, including the corrosion mechanisms, corrosion inhibitor and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviors of steels in liquid lead and lead-bismuth are predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead bismuth as heat transfer media.

Zhang, Jinsuo [Los Alamos National Laboratory

2008-01-01

342

Watching bismuth nanowires grow  

SciTech Connect

We report real-time high temperature scanning electron microscopy observations of the growth of bismuth nanowires via the on-film formation of nanowires (OFF-ON) method. These observations provide experimental evidence that thermally induced-stress on a Bi film is the driving force for the growth of Bi nanowires with high aspect ratios, uniform diameter, and high-quality crystallinity. Our results show that immobile grain boundaries in the Bi film are required for the growth of nanowires so that grain broadening resulting in hillock formation can be prevented. This study not only provides an understanding of the underlying mechanism, but also affords a strategy for facilitating nanowire growth by OFF-ON.

Ham, Jinhee; Lee, Wooyoung [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon, Seoul 120-749 (Korea, Republic of); Shim, Wooyoung [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon, Seoul 120-749 (Korea, Republic of); Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Kim, Do Hyun; Oh, Kyu Hwan [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Voorhees, Peter W. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

2011-01-24

343

Comparison between transient and frequency modulated excitation: application to silicon nitride and aluminum oxide coatings of silicon.  

PubMed

Contactless measurements of the lifetime of charge carriers are presented with varying ways of photo excitation: with and without bias light and pulsed and frequency modulated. These methods are applied to the study of the surface passivation of single crystalline silicon by a-SiN(x):H and Al2O3 coatings. The properties of these coatings are investigated under consideration of the merits of the different methods. PMID:24985850

Klein, D; Ohm, W; Fengler, S; Kunst, M

2014-06-01

344

Thick film silver metallizations for silicon solar cells  

Microsoft Academic Search

Thick film conductor compositions containing silver powder and lead bismuthate glass frit powder and an organic vehicle\\/solvent system are presented for use as grid metallizations to the n-type layers of n- on p- silicon solar cells.

Needes

1980-01-01

345

Gold-bismuth clusters.  

PubMed

Metal clusters have interesting characteristics, such as the relationship between properties and size of the cluster. This is not always apparent, so theoretical studies can provide relevant information. In this report, optimized structures and electron donor-acceptor properties of AunBim clusters are reported (n + m = 2-7, 20). Density functional theory calculations were performed to obtain optimized structures. The ground states of gold clusters formed with up to seven atoms are planar. The presence of Bi modifies the structure, and the clusters become 3-D. Several optimized geometries have at least one Bi atom bonded to gold or bismuth atoms and form structures similar to NH3. This fragment is also present in clusters with 20 atoms, where the formation of Au3Bi stabilizes the structures. Bismuth clusters are better electron donors and worse electron acceptors than gold clusters. Mixed clusters fall in between these two extremes. The presence of Bi atoms in gold clusters modifies the electron donor-acceptor properties of the clusters, but there is no correlation between the number of Bi atoms present in the cluster and the capacity for donating electrons. The effect of planarity in Au19Bi clusters is the same as that in Au20 clusters. The properties of pure gold clusters are certainly interesting, but clusters formed by Bi and Au are more important because the introduction of different atoms modifies the geometry, the stability, and consequently the physical and chemical properties. Apparently, the presence of Bi may increase the reactivity of gold clusters, but further studies are necessary to corroborate this hypothesis. PMID:24963953

Martínez, Ana

2014-08-01

346

Properties of silicon oxide films deposited by plasma-enhanced CVD using organosilicon reactants and mass analysis in plasma  

Microsoft Academic Search

Silicon oxide films were deposited at room temperature on Si substrates by remote-type plasma enhanced chemical vapor deposition using tetramethoxysilane and oxygen. Fourier transform infrared spectroscopy revealed that the carbon contamination in the deposited films are in the state of Si-CH3. Quantitative analysis by X-ray photoelectron spectroscopy elucidated that the oxygen partial pressure ratio is needed to be <40% in

Yasushi Inoue; Osamu Takai

1999-01-01

347

Role of fluorine atoms in the oxidation-hydrolysis process of plasma assisted chemical vapor deposition fluorinated silicon nitride film  

Microsoft Academic Search

The oxidation and\\/or hydrolysis of a plasma assisted chemical vapor deposition fluorinated silicon nitride film in a moisture atmosphere has been studied. The film presents fluorine atoms incorporated as -SiF, -SiF[sub 2], -SiF[sub 3], and [-SiF[sub 2]-][sub n] groups. The open structure of the film, due to the high fluorine content as [-SiF[sub 2]-][sub n], favors the penetration of oxygen

O. Sanchez; C. Gomez-Aleixandre; C. Palacio

2009-01-01

348

Porous silicon carbide and aluminum oxide with unidirectional open porosity as model target materials for radioisotope beam production  

NASA Astrophysics Data System (ADS)

New silicon carbide (SiC) and aluminum oxide (Al2O3) of a tailor-made microstructure were produced using the ice-templating technique, which permits controlled pore formation conditions within the material. These prototypes will serve to verify aging of the new advanced target materials under irradiation with proton beams. Before this, the evaluation of their mechanical integrity was made based on the energy deposition spectra produced by FLUKA codes.

Czapski, M.; Stora, T.; Tardivat, C.; Deville, S.; Santos Augusto, R.; Leloup, J.; Bouville, F.; Fernandes Luis, R.

2013-12-01

349

Development of an emitter for industrial silicon solar cells using the doped oxide solid source diffusion technique  

Microsoft Academic Search

The aim of this paper is to demonstrate for the first time the feasibility of fabricating large-area screen-printed monocrystalline silicon solar cells using the Doped Oxide Solid Source (DOSS) diffusion technique. This process was applied to form the n+p emitter junction from highly doped sources prepared in a POCl3 ambient. The diffusions were performed under a pure nitrogen flow in

R. Chaoui; A. Messaoud; M. L. Zitouni; M. R. Charif

2001-01-01

350

Enhanced Light Emission of Light-Emitting Diodes with Silicon Oxide Nanobowls Photonic Crystal without Electrical Performance Damages  

NASA Astrophysics Data System (ADS)

Unencapsulated GaN-based light-emitting diodes (LEDs) with two-dimensional (2D) hexagonal closely-packed silicon oxide nanobowls photonic crystal (PhC) on the indium tin oxide (ITO) transparent conductive layer were fabricated by using polystyrene spheres and sol-gel process. Compared to conventional LEDs with planar ITO layers, the light output power of 600-nm-lattice PhC LEDs was improved by 25.6% at an injection current of 20 mA. Furthermore, electrical performance of the PhC LEDs was damage-free via this chemical technique.

Du, Chengxiao; Geng, Chong; Zheng, Haiyang; Wei, Tongbo; Chen, Yu; Zhang, Yiyun; Wu, Kui; Yan, Qingfeng; Wang, Junxi; Li, Jinmin

2013-04-01

351

Solar water splitting with a composite silicon/metal oxide semiconductor electrode  

NASA Astrophysics Data System (ADS)

We have studied solar water splitting with a composite semiconductor electrode, composed of an n-i-p junction amorphous silicon (a-Si, E g~ 1.7 eV) layer, an indium tin oxide (ITO) layer, and a tungsten trioxide (WO 3, E g 2.8 eV) particulate layer. The n-i-p a-Si layer, which had more accurately a structure of n-type microcrystalline ( c) 3C-SiC:H (25 nm)/i-type a-Si:H (400 nm)/p-type a-SiC x:H (25 nm), was prepared on a TiO II-covered F-doped SnO II (FTO)/glass plate by a Hot-Wire CVD method. The ITO layer (100 nm thick) was deposited on the p-type a-Si by the DC magnetron sputtering method, and the WO3 particulate layer was formed by a doctor-blade method, using a colloidal solution of commercial WO 3 powder of 10-30 nm in diameter. The composite electrode thus prepared was finally heat-treated at 300°C for 1 h. The anodic (water oxidation) photocurrent for the composite electrode in 0.1 M Na IISO 4 yielded an IPCE (incident photon to current efficiency) of about 6 % at 400 nm and was stable for more than 24 h. Besides, the onset potential lay a little (by about 0.05 V) more negative than the equilibrium hydrogen evolution potential, indicating a possibility of solar water splitting with no external bias. A preliminary result for the water photooxidation with an "n- GaP/p-Si/Pt dot" electrode is also reported briefly.

Nakato, Yoshihiro; Kato, Naoaki; Imanishi, Akihito; Sugiura, Takashi; Ogawa, Shunsuke; Yoshida, Norimitsu; Nonomura, Shuichi

2006-08-01

352

Homopolyatomic Bismuth Ions, Part 2= Electronic Excitations in Homopolyatomic Bismuth Cations: Spectroscopic  

E-print Network

Homopolyatomic Bismuth Ions, Part 2= Electronic Excitations in Homopolyatomic Bismuth Cations of the low-valence bismuth cluster cations Bi5 3 , Bi8 2 , and Bi9 5 have been studied with experimental and theoretical tech- niques. The UV-visible spectra of the bismuth ions were measured in acidic chloroaluminate

Glaser, Rainer

353

Oxidation of nanopores in a silicon membrane: self-limiting formation of sub-10 nm circular openings.  

PubMed

We describe a simple but reliable approach to shrink silicon nanopores with nanometer precision for potential high throughput biomolecular sensing and parallel DNA sequencing. Here, nanopore arrays on silicon membranes were fabricated by a self-limiting shrinkage of inverted pyramidal pores using dry thermal oxidation at 850 °C. The shrinkage rate of the pores with various initial sizes saturated after 4 h of oxidation. In the saturation regime, the shrinkage rate is within ± 2 nm h(-1). Oxidized pores with an average diameter of 32 nm were obtained with perfect circular shape. By careful design of the initial pore size, nanopores with diameters as small as 8 nm have been observed. Statistics of the pore width show that the shrinkage process did not broaden the pore size distribution; in most cases the distribution even decreased slightly. The progression of the oxidation and the deformation of the oxide around the pores were characterized by focused ion beam and electron microscopy. Cross-sectional imaging of the pores suggests that the initial inverted pyramidal geometry is most likely the determining factor for the self-limiting shrinkage. PMID:25116147

Zhang, Miao; Schmidt, Torsten; Sangghaleh, Fatemeh; Roxhed, Niclas; Sychugov, Ilya; Linnros, Jan

2014-09-01

354

Investigations of nanocomposite magnetic materials based on the oxides of iron, nickel, cobalt and silicon dioxide  

NASA Astrophysics Data System (ADS)

This paper is concerned with the study of magnetic nanocomposites containing silicon, iron, nickel, and cobalt oxides. These materials were produced in the form of thin films based on Fe-Si-O, Ni-Co-Si-O and Fe-Ni-Co-Si-O systems and powders based on Fe-Si-O, Ni-Si-O, Co-Si-O and Fe-Ni-Co-Si-O systems using sol-gel technology, through centrifugation, and deposition of ammonia solution. The morphology and magnetic properties of materials in the form of thin films were studied by using the atomic force microscopy. The phase composition, specific surface area and magnetic properties of materials in the form of powders were studied by using the X-ray phase analysis, thermal desorption, vibrational magnetometry and immittance measurements. The dependencies of the main parameters were derived for the magnetic materials from their structure and manufacturing conditions. Ways to optimise the technological processes were proposed, aimed at reducing the size of the magnetic particles in an amorphous lattice.

Gracheva, Irina E.; Olchowik, Grazyna; Gareev, Kamil G.; Moshnikov, Vyatcheslav A.; Kuznetsov, Vladimir V.; Olchowik, Jan M.

2013-05-01

355

Simple coupling chemistry linking carboxyl-containing organic molecules to silicon oxide surfaces under acidic conditions.  

PubMed

The coupling chemistry of carboxymethylated amylose with organo-silanized silicon oxide surfaces at pH 7.4 and 2.0 was investigated using atomic force microscopy (AFM) based single-molecule force spectroscopy. At close to neutral pH, carbodiimide activation of a carboxylic acid affords formation of an amide bond with an amino surface linker. At pH 2.0, no activation with carbodiimide was required to anchor carboxymethylated amylose between an AFM tip and a glass substrate. At the same time, the mean bond rupture force f(r) dropped from 1.65 ± 0.37 nN at pH 7.4 to 1.39 ± 0.30 nN at pH 2.0 without carbodiimide, indicating that a different link to the surface can be formed at low pH. The coupling mechanism at pH 2.0 was elucidated by a series of experiments, in which the surface was functionalized with four different organosilanes, each containing characteristic functional groups. The results are rationalized with an acid-catalyzed ester condensation between a carboxyl group and a free, unreacted silanol group in the surface anchor or on the surface. PMID:20822126

Schmidt, Sebastian W; Christ, Timo; Glockner, Christian; Beyer, Martin K; Clausen-Schaumann, Hauke

2010-10-01

356

Aluminum oxide passivated radial junction sub-micrometre pillar array textured silicon solar cells  

NASA Astrophysics Data System (ADS)

We report radial, p-n junction, sub-micrometre, pillar array textured solar cells, fabricated on an n-type Czochralski silicon wafer. Relatively simple processing schemes such as metal-assisted chemical etching and spin on dopant techniques were employed for the fabrication of the proposed solar cells. Atomic layer deposition (ALD) grown aluminum oxide (Al2O3) was employed as a surface passivation layer on the B-doped emitter surface. In spite of the fact that the sub-micrometre pillar array textured surface has a relatively high surface-to-volume ratio, we observed an open circuit voltage (VOC) and a short circuit current density (JSC) as high as 572 mV and 29.9 mA cm-2, respectively, which leads to a power conversion efficiency in excess of 11.30%, for the optimized structure of the solar cell described herein. Broadband omnidirectional antireflection effects along with the light trapping property of the sub-micrometre, pillar array textured surface and the excellent passivation quality of the ALD-grown Al2O3 on the B-doped emitter surface were responsible for the enhanced electrical performance of the proposed solar cells.

Pudasaini, Pushpa Raj; Elam, David; Ayon, Arturo A.

2013-06-01

357

Plasma enhanced chemical vapor deposition of silicon oxide films with divinyldimethylsilane and tetravinylsilane  

SciTech Connect

Carbon-doped silicon oxide (SiCOH) low-k films were deposited with plasma enhanced chemical vapor deposition (PECVD) using divinyldimethylsilane (DVDMS) with two vinyl groups and tetravinylsilane (TVS) with four vinyl groups compared with vinyltrimethylsilane (VTMS) with one vinyl group. With more vinyl groups in the precursor, due to the crosslinking of the vinyl groups, the film contains more of an organic phase and organic phase became less volatile. It was confirmed that the deposition rate, refractive index, and k value increase with more vinyl groups in the precursor molecule. After annealing, the SiCOH films deposited with DVDMS and TVS showed a low dielectric constant of 2.2 and 2.4 at optimum conditions, respectively. In both cases, the annealed film had low leakage current density (J=6.7x10{sup -7} A/cm{sup 2} for SiCOH film of DVDMS and J=1.18x10{sup -8} A/cm{sup 2} for SiCOH film of TVS at 1 MV/cm) and relatively high breakdown field strength (E>4.0 MV/cm at 1 mA/cm{sup 2}), which is comparable to those of PECVD SiO{sub 2}.

Park, Sung-Gyu; Rhee, Shi-Woo [Department of Chemical Engineering, Laboratory for Advanced Molecular Processing, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2006-03-15

358

Size-tunable silicon/iron oxide hybrid nanoparticles with fluorescence, superparamagnetism, and biocompatibility.  

PubMed

Magnetic/fluorescent composite materials have become one of the most important tools in the imaging modality in vivo using magnetic resonance imaging (MRI) monitoring and fluorescence optical imaging. We report herein on a simplified procedure to synthesize hybrid nanoparticles (HNPs) that combine silicon and magnetic iron oxides consisting of magnetite (Fe(3)O(4)) and maghemite (?-Fe(2)O(3)). Intriguingly, our unique synthetic approach can control magnetic and optical behaviors by reducing the particle size, demonstrating that the HNPs with the mean diameter of 3.0 nm exhibit superparamagnetic behavior and green fluorescence in an aqueous solution, ambient air, and a cellular environment, whereas the HNPs with the mean diameter more than 5.0 nm indicate ferromagnetic behavior without fluorescence. Additionally, both HNPs with different diameters possess excellent magnetic responsivity for external applied magnetic field and good biocompatibility due to the low cytotoxicity. Our biocompatible HNPs with the superparamagnetism can provide an attractive approach for diagnostic imaging system in vivo. PMID:21991945

Sato, Keisuke; Yokosuka, Shinobu; Takigami, Yasunori; Hirakuri, Kenji; Fujioka, Kouki; Manome, Yoshinobu; Sukegawa, Hiroaki; Iwai, Hideo; Fukata, Naoki

2011-11-23

359

Island growth in the atomic layer deposition of zirconium oxide and aluminum oxide on hydrogen-terminated silicon: Growth mode modeling and transmission electron microscopy  

NASA Astrophysics Data System (ADS)

Atomic layer deposition (ALD) is used in applications where inorganic material layers with uniform thickness down to the nanometer range are required. For such thicknesses, the growth mode, defining how the material is arranged on the surface during the growth, is of critical importance. In this work, the growth mode of the zirconium tetrachloride/water and the trimethyl aluminum/water ALD process on hydrogen-terminated silicon was investigated by combining information on the total amount of material deposited with information on the surface fraction of the material. The total amount of material deposited was measured by Rutherford backscattering, x-ray fluorescence, and inductively coupled plasma-optical emission spectroscopy, and the surface fractions by low-energy ion scattering. Growth mode modeling was made assuming two-dimensional growth or random deposition (RD), with a "shower model" of RD recently developed for ALD. Experimental surface fractions of the ALD-grown zirconium oxide and aluminum oxide films were lower than the surface fractions calculated assuming RD, suggesting the occurrence of island growth. Island growth was confirmed with transmission electron microscopy (TEM) measurements, from which the island size and number of islands per unit surface area could also be estimated. The conclusion of island growth for the aluminum oxide deposition on hydrogen-terminated silicon contradicts earlier observations. In this work, physical aluminum oxide islands were observed in TEM after 15 ALD reaction cycles. Earlier, thicker aluminum oxide layers have been analyzed, where islands have not been observed because they have already coalesced to form a continuous film. The unreactivity of hydrogen-terminated silicon surface towards the ALD reactants, except for reactive defect areas, is proposed as the origin of island growth. Consequently, island growth can be regarded as "undesired surface-selective ALD."

Puurunen, Riikka L.; Vandervorst, Wilfried; Besling, Wim F. A.; Richard, Olivier; Bender, Hugo; Conard, Thierry; Zhao, Chao; Delabie, Annelies; Caymax, Matty; De Gendt, Stefan; Heyns, Marc; Viitanen, Minna M.; de Ridder, Marco; Brongersma, Hidde H.; Tamminga, Yde; Dao, Thuy; de Win, Toon; Verheijen, Marcel; Kaiser, Monja; Tuominen, Marko

2004-11-01

360

The optical properties of bismuth nanowires  

E-print Network

The optical absorption of bismuth nanowires in the energy (wavenumber) range of 600 - 4000cm-1 is studied. Optical reflection and transmission spectra reveal that bismuth nanowires have a large and intense absorption peak ...

Black, Marcie R. (Marcie Rochelle)

2003-01-01

361

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2012 CFR

...Specifications. The color additive bismuth oxychloride...be avoided by good manufacturing practice: Volatile...restrictions. The color additive bismuth oxychloride...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2012-04-01

362

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2013 CFR

...Specifications. The color additive bismuth oxychloride...be avoided by good manufacturing practice: Volatile...restrictions. The color additive bismuth oxychloride...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2013-04-01

363

Behaviour of Antimony and Bismuth in Copper Electrorefining Circuits  

SciTech Connect

Antimony- and bismuth-rich copper anodes, anode slimes and decopperized anode slimes from industrial copper electrorefineries were studied mineralogically. Antimony in the anodes occurs mainly as Cu-Pb-As-Sb-Bi oxide inclusions along the copper grain boundaries; bismuth is mainly present as Cu-Pb-As-Sb-Bi oxide, Cu-Bi-As oxide, Cu-Pb-As-Bi oxide and Cu-Bi oxide inclusions. Sb and Bi partly dissolve during electrorefining, but extensively reprecipitate as As-Sb oxide, As-Sb-Bi oxide and SbAsO4. The presence of As results in the precipitation of essentially all the Bi as BiAsO4. The decopperizing process dissolves much of the Sb and Bi, although the majority of the BiAsO4 phase remains unaffected. Subsequently, some of the dissolved Sb and Bi reprecipitates as various oxide, sulphate and arsenate species. X-ray absorption near-edge structure (XANES) analyses suggest about 70% of the antimony in the anode slimes is present in the pentavalent oxidation state. The XANES analyses indicate that most of the Bi in all the slimes samples is present in the trivalent oxidation state.

Beauchemin,S.; Chen, T.; Dutrizac, J.

2008-01-01

364

Excitation mechanism and thermal emission quenching of Tb ions in silicon rich silicon oxide thin films grown by plasma-enhanced chemical vapour deposition—Do we need silicon nanoclusters?  

NASA Astrophysics Data System (ADS)

In this work, we will discuss the excitation and emission properties of Tb ions in a Silicon Rich Silicon Oxide (SRSO) matrix obtained at different technological conditions. By means of electron cyclotron resonance plasma-enhanced chemical vapour deposition, undoped and doped SRSO films have been obtained with different Si content (33, 35, 39, 50 at. %) and were annealed at different temperatures (600, 900, 1100 °C). The samples were characterized optically and structurally using photoluminescence (PL), PL excitation, time resolved PL, absorption, cathodoluminescence, temperature dependent PL, Rutherford backscattering spectrometry, Fourier transform infrared spectroscopy and positron annihilation lifetime spectroscopy. Based on the obtained results, we discuss how the matrix modifications influence excitation and emission properties of Tb ions.

Podhorodecki, A.; Golacki, L. W.; Zatryb, G.; Misiewicz, J.; Wang, J.; Jadwisienczak, W.; Fedus, K.; Wojcik, J.; Wilson, P. R. J.; Mascher, P.

2014-04-01

365

Mineral resource of the month: bismuth  

USGS Publications Warehouse

Bismuth compounds are most known for their soothing effects on the stomach, wounds and sores. These properties make the compounds an essential part of many medicinal and cosmetic preparations, which until 1930 accounted for about 90 percent of the bismuth used. The subsequent development of low-melting alloys and chemical catalysts containing bismuth, as well as its use as an additive to casting alloys, has resulted in a wider variety of industrial applications for bismuth.

Carlin, James F.

2006-01-01

366

Nano sized bismuth oxy chloride by metal organic chemical vapour deposition  

NASA Astrophysics Data System (ADS)

Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl3) in acetone (CH3sbnd COsbnd CH3). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18-250 nm thick and a few micrometres wide.

Jagdale, Pravin; Castellino, Micaela; Marrec, Françoise; Rodil, Sandra E.; Tagliaferro, Alberto

2014-06-01

367

A high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor  

Microsoft Academic Search

Silicon has long been the optimal material for electronics, but it is only relatively recently that it has been considered as a material option for photonics. One of the key limitations for using silicon as a photonic material has been the relatively low speed of silicon optical modulators compared to those fabricated from III-V semiconductor compounds and\\/or electro-optic materials such

Ansheng Liu; Richard Jones; Ling Liao; Dean Samara-Rubio; Doron Rubin; Oded Cohen; Remus Nicolaescu; Mario Paniccia

2004-01-01

368

Bismuth Passivation Technique for High-Resolution X-Ray Detectors  

NASA Technical Reports Server (NTRS)

The Athena-plus team requires X-ray sensors with energy resolution of better than one part in 3,000 at 6 keV X-rays. While bismuth is an excellent material for high X-ray stopping power and low heat capacity (for large signal when an X-ray is stopped by the absorber), oxidation of the bismuth surface can lead to electron traps and other effects that degrade the energy resolution. Bismuth oxide reduction and nitride passivation techniques analogous to those used in indium passivation are being applied in a new technique. The technique will enable improved energy resolution and resistance to aging in bismuth-absorber-coupled X-ray sensors. Elemental bismuth is lithographically integrated into X-ray detector circuits. It encounters several steps where the Bi oxidizes. The technology discussed here will remove oxide from the surface of the Bi and replace it with nitridized surface. Removal of the native oxide and passivating to prevent the growth of the oxide will improve detector performance and insulate the detector against future degradation from oxide growth. Placing the Bi coated sensor in a vacuum system, a reduction chemistry in a plasma (nitrogen/hydrogen (N2/H2) + argon) is used to remove the oxide and promote nitridization of the cleaned Bi surface. Once passivated, the Bi will perform as a better X-ray thermalizer since energy will not be trapped in the bismuth oxides on the surface. A simple additional step, which can be added at various stages of the current fabrication process, can then be applied to encapsulate the Bi film. After plasma passivation, the Bi can be capped with a non-diffusive layer of metal or dielectric. A non-superconducting layer is required such as tungsten or tungsten nitride (WNx).

Chervenak, James; Hess, Larry

2013-01-01

369

Evaluation of Seebeck coefficients in n- and p-type silicon nanowires fabricated by complementary metal-oxide-semiconductor technology.  

PubMed

Silicon-based thermoelectric nanowires were fabricated by using complementary metal-oxide-semiconductor (CMOS) technology. 50 nm width n- and p-type silicon nanowires (SiNWs) were manufactured using a conventional photolithography method on 8 inch silicon wafer. For the evaluation of the Seebeck coefficients of the silicon nanowires, heater and temperature sensor embedded test patterns were fabricated. Moreover, for the elimination of electrical and thermal contact resistance issues, the SiNWs, heater and temperature sensors were fabricated monolithically using a CMOS process. For validation of the temperature measurement by an electrical method, scanning thermal microscopy analysis was carried out. The highest Seebeck coefficients were - 169.97 ?V K(-1) and 152.82 ?V K(-1) and the highest power factors were 2.77 mW m(-1) K(-2) and 0.65 mW m(-1) K(-2) for n- and p-type SiNWs, respectively, in the temperature range from 200 to 300 K. The larger power factor value for n-type SiNW was due to the higher electrical conductivity. The total Seebeck coefficient and total power factor for the n- and p-leg unit device were 157.66 ?V K(-1) and 9.30 mW m(-1) K(-2) at 300 K, respectively. PMID:22995969

Hyun, Younghoon; Park, Youngsam; Choi, Wonchul; Kim, Jaehyeon; Zyung, Taehyoung; Jang, Moongyu

2012-10-12

370

Third order nonlinear optical properties of bismuth zinc borate glasses  

SciTech Connect

Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi{sub 2}O{sub 3}-30ZnO-(70-x) B{sub 2}O{sub 3} (where x?=?30, 35, 40, and 45?mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (?) and the absorption cross section due to free carriers (?{sub e}) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

Shanmugavelu, B.; Ravi Kanth Kumar, V. V., E-mail: ravi.phy@pondiuni.edu.in [Department of Physics, Pondicherry University, Puducherry 605 014 (India); Kuladeep, R.; Narayana Rao, D. [School of Physics, University of Hyderabad, Hyderabad 500046, Andhra Pradesh (India)

2013-12-28

371

Third order nonlinear optical properties of bismuth zinc borate glasses  

NASA Astrophysics Data System (ADS)

Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi2O3-30ZnO-(70-x) B2O3 (where x = 30, 35, 40, and 45 mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (?) and the absorption cross section due to free carriers (?e) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

Shanmugavelu, B.; Ravi Kanth Kumar, V. V.; Kuladeep, R.; Narayana Rao, D.

2013-12-01

372

Thickness-dependent optimization of Er3+ light emission from silicon-rich silicon oxide thin films  

PubMed Central

This study investigates the influence of the film thickness on the silicon-excess-mediated sensitization of Erbium ions in Si-rich silica. The Er3+ photoluminescence at 1.5 ?m, normalized to the film thickness, was found five times larger for films 1 ?m-thick than that from 50-nm-thick films intended for electrically driven devices. The origin of this difference is shared by changes in the local density of optical states and depth-dependent interferences, and by limited formation of Si-based sensitizers in "thin" films, probably because of the prevailing high stress. More Si excess has significantly increased the emission from "thin" films, up to ten times. This paves the way to the realization of highly efficient electrically excited devices. PMID:21711930

2011-01-01

373

Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires  

PubMed Central

Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO. PMID:23590803

2013-01-01

374

Porous silicon oxide-PLGA composite microspheres for sustained ocular delivery of daunorubicin.  

PubMed

A water-soluble anthracycline antibiotic drug (daunorubicin, DNR) was loaded into oxidized porous silicon (pSiO2) microparticles and then encapsulated with a layer of polymer (poly lactide-co-glycolide, PLGA) to investigate their synergistic effects in control of DNR release. Similarly fabricated PLGA-DNR microspheres without pSiO2, and pSiO2 microparticles without PLGA were used as control particles. The composite microparticles synthesized by a solid-in-oil-in-water emulsion method have mean diameters of 52.33±16.37?m for PLGA-pSiO2_21/40-DNR and the mean diameter of 49.31±8.87?m for PLGA-pSiO2_6/20-DNR. The mean size, 26.00±8?m, of PLGA-DNR was significantly smaller, compared with the other two (P<0.0001). Optical microscopy revealed that PLGA-pSiO2-DNR microspheres contained multiple pSiO2 particles. In vitro release experiments determined that control PLGA-DNR microspheres completely released DNR within 38days and control pSiO2-DNR microparticles (with no PLGA coating) released DNR within 14days, while the PLGA-pSiO2-DNR microspheres released DNR for 74days. Temporal release profiles of DNR from PLGA-pSiO2 composite particles indicated that both PLGA and pSiO2 contribute to the sustained release of the payload. The PLGA-pSiO2 composite displayed a more constant rate of DNR release than the pSiO2 control formulation, and displayed a significantly slower release of DNR than either the PLGA or pSiO2 formulations. We conclude that this system may be useful in managing unwanted ocular proliferation when formulated with antiproliferation compounds such as DNR. PMID:24793657

Nan, Kaihui; Ma, Feiyan; Hou, Huiyuan; Freeman, William R; Sailor, Michael J; Cheng, Lingyun

2014-08-01

375

Auger and X-ray PhotoelectronSpectroscopy Study of the Density ofOxygen States in Bismuth, Aluminum, Silicon, and Uranium Oxides  

SciTech Connect

The correlation of relative partial electron density at the oxygen ions with the intensity of Auger O KLL lines in Bi2O3, Al2O3, SiO2 and UO2 has been determined by Auger and X-ray photoelectron spectroscopic methods. The dependence of the relative intensities of Auger O KL2-3L2-3 and O KL1L2-3-lines was characterized from the binding energy of O 1s electrons. The electron density of the outer valence levels of oxygen increases as the relative intensities of Anger OKL2-3L2-3 and O KL1L2-3-lines increase. The fine structure observed in the O KL1L2-3 Auger and the O 2s XPS spectra has been explained by the formation of inner valence molecular orbitals (IVMO) from the interaction of electrons of the O 2s and filled metal ns shells.

Teterin, Yu A.; Ivanov, K.E.; Teterin, A. Yu; Lebedev, A.M.; Utkin, I.O.; Vukchevich, L.

1998-08-03

376

Silicon/hematite core/shell nanowire array decorated with gold nanoparticles for unbiased solar water oxidation.  

PubMed

We report the facile fabrication of three-dimensional (3D) silicon/hematite core/shell nanowire arrays decorated with gold nanoparticles (AuNPs) and their potential application for sunlight-driven solar water splitting. The hematite and AuNPs respectively play crucial catalytic and plasmonic photosensitization roles, while silicon absorbs visible light and generates high photocurrent. Under simulated solar light illumination, solar water splitting with remarkable efficiency is achieved with no external bias applied. Such a nanocomposite photoanode design offers great promise for unassisted sunlight-driven water oxidation, and further stability and efficiency improvements to the device will lead to exciting prospects for practical solar water splitting and artificial photosynthesis. PMID:24341833

Wang, Xin; Peng, Kui-Qing; Hu, Ya; Zhang, Fu-Qiang; Hu, Bo; Li, Li; Wang, Meng; Meng, Xiang-Min; Lee, Shuit-Tong

2014-01-01

377

Corrosion behavior of Si-enriched steels for nuclear applications in liquid lead-bismuth  

NASA Astrophysics Data System (ADS)

The corrosion behavior of Si-enriched steels in liquid lead-bismuth was studied in order to develop accelerator driven systems for transmutation of long-lived radioactive wastes and lead-bismuth cooled fast reactors. The corrosion tests of 316SS, Si-enriched 316SS, Mod.9Cr-1Mo steel (T91) and Si-enriched T91 were conducted at 550 °C in liquid lead-bismuth at the two controlled oxygen levels. Both the additions of 2.5 wt.% Si to 316SS and 1.5 wt.% Si to T91 had the effect of reducing the thickness of oxide layer in liquid lead-bismuth at the high oxygen concentration (2.5 × 10-5 wt.%). Although the Si addition to 316SS reduced the depth of ferritization caused by Ni dissolution in liquid lead-bismuth at the low oxygen concentration (4.4 × 10-8 wt.%), it could not suppress the ferritization and the penetration of Pb and Bi completely. The Si addition to T91 did not have the effect of preventing the penetration of Pb and Bi in the liquid lead-bismuth at the low oxygen concentration. The oxide scales formed on both Si-enriched steels did not have sufficient corrosion resistance under the low oxygen condition.

Kurata, Yuji

2013-06-01

378

Strong and reversible modulation of carbon nanotube-silicon heterojunction solar cells by an interfacial oxide layer.  

PubMed

Deposition of nanostructures such as carbon nanotubes on Si wafers to make heterojunction structures is a promising route toward high efficiency solar cells with reduced cost. Here, we show a significant enhancement in the cell characteristics and power conversion efficiency by growing a silicon oxide layer at the interface between the nanotube film and Si substrate. The cell efficiency increases steadily from 0.5% without interfacial oxide to 8.8% with an optimal oxide thickness of about 1 nm. This systematic study reveals that formation of an oxide layer switches charge transport from thermionic emission to a mixture of thermionic emission and tunneling and improves overall diode properties, which are critical factors for tailoring the cell behavior. By controlled formation and removal of interfacial oxide, we demonstrate oscillation of the cell parameters between two extreme states, where the cell efficiency can be reversibly altered by a factor of 500. Our results suggest that the oxide layer plays an important role in Si-based photovoltaics, and it might be utilized to tune the cell performance in various nanostructure-Si heterojunction structures. PMID:22573091

Jia, Yi; Cao, Anyuan; Kang, Feiyu; Li, Peixu; Gui, Xuchun; Zhang, Luhui; Shi, Enzheng; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai

2012-06-21

379

Controlling the shape and gap width of silicon electrodes using local anodic oxidation and anisotropic TMAH wet etching  

NASA Astrophysics Data System (ADS)

A simple method for fabricating silicon electrodes with various shapes and gap widths was designed using the special properties of anisotropic tetramethylammonium hydroxide (TMAH) wet etching and local anodic oxidation (LAO). A statistical system was used for the optimization of the parameters of the LAO process to facilitate a better understanding and precise analysis of the process. Analyses of the interaction effects among the significant factors of LAO showed that the relative humidity and applied voltage were interdependent. They had the strongest interaction effect on the dimensions of the oxide mask. TMAH with a concentration of 25% was used as an etchant solution in (1?0?0) silicon with a rectangular oxide mask. The observed undercutting at convex corners, tip shape of emitters and gap widths of electrodes were exactly consistent with theoretical studies. Combination of the LAO method and anisotropic TMAH wet etching was successfully used to fabricate Si nano-gap electrodes. This fabrication method of sharp and round tip emitters was simple, controllable and faster than common techniques. These results indicate that the method can be a new approach for studying the electrical properties of nano-gap electrodes.

Rouhi, Jalal; Mahmud, Shahrom; Derita Hutagalung, Sabar; Naderi, Nima; Kakooei, Saeid; Johar Abdullah, Mat

2012-06-01

380

An Oxygen Control Strategy for Corrosion Minimization in Direct-Contact Lead- Bismuth/Water Systems  

SciTech Connect

The selection of structural materials suitable for fuel cladding and primary system purposes is key to the development of all lead and lead-bismuth cooled nuclear systems. Traditional austenitic stainless steels cannot be used at the temperatures of interest (>450 deg. C), because of the large solubility of nickel in bismuth. The possibility of employing low nickel martensitic/ferritic stainless steels is currently being studied. Corrosion control for these alloys is based on the formation of a stable iron oxide film on the surfaces exposed to the liquid-metal coolant. This requires maintenance of at least a minimum concentration of oxygen in the liquid metal. On the other hand, excessive oxygen can cause precipitation of lead- and bismuth-oxide slag. Excessive oxidation of the coolant is particularly challenging in the case of a direct-contact system where lead-bismuth and water are mixed to generate steam. In this paper it is demonstrated that an oxygen control strategy based on injection of minute amounts of hydrogen in the feedwater can ensure formation of the stable iron film, while preventing precipitation of the liquid-metal oxides. This corrosion-control approach is quantified in the context of a conceptual lead-bismuth-cooled fast reactor of recent development, which makes use of in-vessel direct-contact generation of the working steam. (authors)

Buongiorno, Jacopo [Idaho National Engineering and Environmental Laboratory, Nuclear Engineering Department, P.O. Box 1625, Idaho Falls, ID 83415-3860 (United States); Todreas, Neil E.; Kazimi, Mujid S. [Massachusetts Institute of Technology, Nuclear Engineering Department, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States)

2002-07-01

381

Characterization of lead-bismuth eutectic nanowires  

NASA Astrophysics Data System (ADS)

In this work, lead-bismuth eutectic alloy nanowires were fabricated by a novel vacuum melting method and centrifugal process. An anodic aluminum oxide (AAO) template was used to produce an array of ordered, dense, and continuous Pb-Bi nanowires. Scanning electron microscopy and transmission electron microscopy investigations reveal that nanowires with a diameter of 80 nm are composed of Pb7Bi3 and Bi phases, and have a single orientation of growth. Magnetic susceptibility and hysteresis measurements have been used to characterize the superconductive and magnetic properties of the nanowires. The results show that Pb-Bi nanowires have a slightly lower superconducting transition temperature than Pb-Bi eutectic alloy bulk, and only about 1% superconductivity volume fraction in magnetic fields both perpendicular and parallel to the plate. In magnetization curves, a fairly large hysteresis is observed for both field orientations.

Kuo, C. G.; Hsu, Y. Y.; Wu, M. K.; Chao, C. G.

2005-04-01

382

Atomic Layer Deposition and Properties of Silicon Oxide Thin Films Using Alternating Exposures to SiH2Cl2 and O3  

NASA Astrophysics Data System (ADS)

We report the process for the atomic layer deposition (ALD) of silicon dioxide thin films on a silicon wafer by alternating exposures to SiH2Cl2 and O3. The growth kinetics of silicon oxide films was examined by varying reactant exposures at various deposition temperatures ranging from 250 to 450 °C. The deposition was governed by a self-limiting surface reaction, and the growth rate at 350 °C was saturated at 0.25 nm/cycle for SiH2Cl2 exposures of over 5× 109 L (10-6 Torr\\cdots). The chlorine content and the wet-etching rate in a diluted HF solution were reduced by increasing the deposition temperature. The films deposited at temperatures ranging from 350 to 450 °C exhibited excellent physical and electrical properties that were equivalent to those of silicon oxide films deposited at 760 °C by low-pressure chemical vapor deposition.

Won-Jun Lee,; Chang-Hee Han,; Jae-Kyun Park,; Youn-Seoung Lee,; Sa-Kyun Rha,

2010-07-01

383

Atomic Layer Deposition and Properties of Silicon Oxide Thin Films Using Alternating Exposures to SiH2Cl2 and O3  

NASA Astrophysics Data System (ADS)

We report the process for the atomic layer deposition (ALD) of silicon dioxide thin films on a silicon wafer by alternating exposures to SiH2Cl2 and O3. The growth kinetics of silicon oxide films was examined by varying reactant exposures at various deposition temperatures ranging from 250 to 450 °C. The deposition was governed by a self-limiting surface reaction, and the growth rate at 350 °C was saturated at 0.25 nm/cycle for SiH2Cl2 exposures of over 5×109 L (10-6 Torr·s). The chlorine content and the wet-etching rate in a diluted HF solution were reduced by increasing the deposition temperature. The films deposited at temperatures ranging from 350 to 450 °C exhibited excellent physical and electrical properties that were equivalent to those of silicon oxide films deposited at 760 °C by low-pressure chemical vapor deposition.

Lee, Won-Jun; Han, Chang-Hee; Park, Jae-Kyun; Lee, Youn-Seoung; Rha, Sa-Kyun

2010-07-01

384

Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry  

NASA Astrophysics Data System (ADS)

We present transport measurements of a tunable silicon metal-oxide semiconductor double quantum dot device with lateral geometry. The experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. A comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling.

Tracy, L. A.; Nordberg, E. P.; Young, R. W.; Borrás Pinilla, C.; Stalford, H. L.; Ten Eyck, G. A.; Eng, K.; Childs, K. D.; Wendt, J. R.; Grubbs, R. K.; Stevens, J.; Lilly, M. P.; Eriksson, M. A.; Carroll, M. S.

2010-11-01

385

Deterministic assembly of releasable single crystal silicon-metal oxide field-effect devices formed from bulk wafers  

NASA Astrophysics Data System (ADS)

Deterministic assembly of ultrathin metal oxide-semiconductor field-effect transistors released from the surfaces of bulk wafers with (111) orientation provides a route to high quality electronics on nearly any type of substrate. Device parameters and bias stability characteristics from transistors on sheets of plastic confirm the effectiveness of the approach and the critical roles of thermally grown layers of silicon dioxide for the gate dielectrics and passivation layers. Systematic studies of the anisotropic etching processes used to release the devices illustrate capabilities into the sub-micron thickness regime, with beneficial effects on the bending stiffness and degree of bendability.

Kim, Tae-il; Hwan Jung, Yei; Chung, Hyun-Joong; Jun Yu, Ki; Ahmed, Numair; Corcoran, Christopher J.; Suk Park, Jae; Hun Jin, Sung; Rogers, John A.

2013-05-01

386

Novel processing of bioglass ceramics from silicone resins containing micro- and nano-sized oxide particle fillers.  

PubMed

Highly porous scaffolds with composition similar to those of 45S5 and 58S bioglasses were successfully produced by an innovative processing method based on preceramic polymers containing micro- and nano-sized fillers. Silica from the decomposition of the silicone resins reacted with the oxides deriving from the fillers, yielding glass ceramic components after heating at 1000°C. Despite the limited mechanical strength, the obtained samples possessed suitable porous architecture and promising biocompatibility and bioactivity characteristics, as testified by preliminary in vitro tests. PMID:23946157

Fiocco, L; Bernardo, E; Colombo, P; Cacciotti, I; Bianco, A; Bellucci, D; Sola, A; Cannillo, V

2014-08-01

387

Improved memory performance of metal—oxide—nitride—oxide—silicon by annealing the SiO2 tunnel layer in different nitridation atmospheres  

NASA Astrophysics Data System (ADS)

Metal—oxide—nitride—oxide—silicon (MONOS) capacitors with thermally grown SiO2 as the tunnel layer are fabricated, and the effects of different ambient nitridation (NH3, NO and N2O) on the characteristics of the memory capacitors are investigated. The experimental results indicate that the device with tunnel oxide annealed in NO ambient exhibits excellent memory characteristics, i.e. a large memory window, high program/erase speed, and good endurance and retention performance (the charge loss rate is 14.5% after 10 years). The mechanism involved is that much more nitrogen is incorporated into the tunnel oxide during NO annealing, resulting in a lower tunneling barrier height and smaller interface state density. Thus, there is a higher tunneling rate under a high electric field and a lower probability of trap-assisted tunneling during retention, as compared to N2O annealing. Furthermore, compared with the NH3-annealed device, no weak Si—H bonds and electron traps related to the hydrogen are introduced for the NO-annealed devices, giving a high-quality and high-reliability SiON tunneling layer and SiON/Si interface due to the suitable nitridation and oxidation roles of NO.

Meilin, He; Jingping, Xu; Jianxiong, Chen; Lu, Liu

2013-11-01

388

Effects of Applied Mechanical Uniaxial and Biaxial Tensile Strain on the Flatband Voltage of (001), (110), and (111) Metal–Oxide–Silicon Capacitors  

Microsoft Academic Search

The flatband-voltage shift of metal-oxide-silicon capacitors is investigated under the application of low-level stress (up to 220 MPa of biaxial stress and 380 MPa of uniaxial stress) to different substrate orientations. We propose that the flatband-voltage shift be modeled as the net effect of silicon-band-edge shifts and modulation of the separation between the band edge and the Fermi level under

Cheng-Yi Peng; Ying-Jhe Yang; Yen-Chun Fu; Ching-Fang Huang; Shu-Tong Chang; Chee Wee Liu

2009-01-01

389

Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts  

NASA Technical Reports Server (NTRS)

Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

Bhatt, R. T.; Palczer, A. R.

1998-01-01

390

Transport properties of bismuth films  

Microsoft Academic Search

Glass-coated bismuth films were deposited onto a glass substrate at room temperature and their Hall coefficients and electrical resistivities were measured between 77 and 300°K. Scanning electron micrographs revealed that the films prepared in this way were more polycrystalline than those deposited onto a heated mica substrate. Interesting features were found in the temperature dependence of the Hall coefficient: the

Masasi Inoue; Yukio Tamaki; Hisao Yagi

1974-01-01

391

Materials Science and Engineering A259 (1999) 6572 Mechanical properties of oxidized silicon nitride ceramics  

E-print Network

decreases upon oxidation at 1000°C. A reduction of the elastic modulus of the materials oxidized at 1400°C strength and elastic modulus of the whole oxidized material and of hardness, the fracture toughness and elastic modulus of the internal region (without the strongly oxidized surface layer) are determined

Gubicza, Jenõ

392

Oxygen impurity effects at metal/silicide interfaces - Formation of silicon oxide and suboxides in the Ni/Si system  

NASA Technical Reports Server (NTRS)

The effect of implanted oxygen impurities on the Ni/Ni2Si interface is investigated using X-ray photoelectron spectroscopy, He-4(+) backscattering and O(d, alpha)-16 N-14 nuclear reactions. Oxygen dosages corresponding to concentrations of 1, 2, and 3 atomic percent were implanted into Ni films evaporated on Si substrates. The oxygen, nickel, and silicon core lines were monitored as a function of time during in situ growth of the Ni silicide to determine the chemical nature of the diffusion barrier which forms in the presence of oxygen impurities. Analysis of the Ni, Si, and O core levels demonstrates that the formation of SiO2 is responsible for the Ni diffusion barrier rather than Ni oxide or mixed oxides, such as Ni2SiO4. It is determined that 2.2 x 10 to the 16th O/qu cm is sufficient to prevent Ni diffusion under UHV annealing conditions.

Grunthaner, P. J.; Grunthaner, F. J.; Scott, D. M.; Nicolet, M.-A.; Mayer, J. W.

1981-01-01

393

Effect of substrate crystalline morphology on the adhesion of plasma enhanced chemical vapor deposited thin silicon oxide coatings on polyamide  

NASA Astrophysics Data System (ADS)

The influence of the surface morphology of semicrystalline polyamide 12 (PA12) on the adhesion of thin silicon oxide coatings is analyzed by means of uniaxial fragmentation tests and scanning local-acceleration microscopy (SLAM). Two types of PA12 substrates are investigated, namely, as-received PA12, which contains large spherulites, and quenched PA12, which has a relatively smooth, homogeneous surface structure. The adhesion of the coating is found to be identical for the two types of PA12. This indicates that plasma deposition of the oxide leads to an equivalent functionalization of the two types of surfaces. Nonetheless, localized delamination is observed at spherulite boundaries, and is argued to result from strain concentrations in the corresponding soft zones, revealed by SLAM measurements.

Rochat, G.; Leterrier, Y.; Plummer, C. J. G.; Mânson, J.-A. E.; Szoszkiewicz, R.; Kulik, A. J.; Fayet, P.

2004-05-01

394

Formation and characterization of porous silicon-samarium/gadolinium nanocomposites: effect of substrate oxidation and biosynthesis process  

NASA Astrophysics Data System (ADS)

Samarium and gadolinium nanoparticles synthesized by bioreduction process have been incorporated into nanostructured porous silicon template to form a nanocomposite. The structural and optical properties of PS-Gd and PS-Sm nanocomposites have been studied through TEM, SEM and UV-Vis spectroscopy. Extent of infiltration has been verified through reflectance interference Fourier transform spectroscopy as a function of substrate oxidation conditions. The substrates oxidized at 600 °C showed the maximum infiltration and the corresponding change of optical thickness due to nanoparticles. Such biodegradable nanocomposites in the form of particles can have potential applications in localized drug delivery and enhancement of the image contrast and optoelectronic devices. The results here reported open an energy-cheap procedure to take advantages of small rare earth nanoparticles and produced nanocomposites with their immersion in SiO2 substrates, with the perspective to be replied in other similar substrates under controlled conditions.

Perdigon-Lagunes, P.; Ascencio, J. A.; Agarwal, V.

2014-08-01

395

21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Kanamycin, bismuth subcarbonate, activated attapulgite...ANIMAL DRUGS § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite...kanamycin (as the sulfate), 250 mg bismuth subcarbonate, and 500 mg activated...

2010-04-01

396

Biamperometric neutralisation titrations using the bismuth-bismuth pair of electrodes  

Microsoft Academic Search

Summary  It has been shown that the simple biamperometric technique using a bismuth-bismuth pair of electrodes, can be applied to titrimetric\\u000a determinations of either strong or weak acids, when alone or in mixture.

Momir S. Jovanovi?; Dubravka Bakale

1969-01-01

397

The origin of visible photoluminescence from silicon oxide thin films prepared by dual-plasma chemical vapor deposition  

NASA Astrophysics Data System (ADS)

In order to understand the radiative recombination mechanisms in silicon oxides, photoluminescence properties (PL) of H-rich amorphous silicon oxide thin films grown in a dual-plasma chemical vapor deposition reactor have been related to a number of stoichiometry and structure characterizations (x-ray photoelectron spectroscopy, vibrational spectroscopy, and gas evolution studies). The visible photoluminescence at room temperature from a-SiOx:H matrixes with different compositions, including different bonding environments for H atoms, has been studied in the as-deposited and annealed states up to 900 °C. Three commonly reported PL bands centered around 1.7, 2.1, and 2.9 eV have been detected from the same type of a-SiOx:H material, only by varying the oxygen content (x = 1.35, 1.65, and 2). Temperature quenching experiments are crucial to distinguish the 1.7 eV band, fully consistent with bandtail-to-bandtail recombination, from the radiative defect luminescence mechanisms attributed either to defects related to Si-OH groups (2.9 eV) or to oxygen-vacancy defects (2.1 eV). In the latter case, a red-shift of the PL peak energy as a function of annealing temperature is probably attributed to some matrix-induced strain effect.

Zhu, M.; Han, Y.; Wehrspohn, R. B.; Godet, C.; Etemadi, R.; Ballutaud, D.

1998-05-01

398

Attenuated total reflectance infrared spectroscopy study of hysteresis of water and n-alcohol coadsorption on silicon oxide.  

PubMed

The structure and thickness of the binary adsorbate layers formed on silicon oxide exposed in n-propanol/water and n-pentanol/water vapor mixtures under atmospheric pressure and room temperature conditions were investigated using attenuated total reflectance infrared spectroscopy (ATR-IR). The ATR-IR spectra of the adsorbate layers were analyzed while the vapor composition was varied stepwise by changing the mixing ratios of (a) n-propanol vapor stream with a 94% relative partial pressure (P/P(sat)) and 94% P/P(sat) water stream and (b) 83% P/P(sat)n-pentanol and 85% P/P(sat) water streams. The amount of the adsorbed water with solid-like structure in the binary adsorbate layer was larger in successive cycles of the water/alcohol vapor composition change, while n-alcohol showed negligible hysteresis in the amount adsorbed. The hysteresis behavior of the solid-like water structure was amplified in the coadsorption cycles of alcohol and water as compared to the water-only case. The origin of this behavior must be attributed to the structure of the alcohol/water binary adsorbate layer. The n-alcohol molecules present at the adsorbate/vapor interface can lower the surface energy of the system and stabilize the solid-like water structure in the alcohol-water binary adsorbate layer on silicon oxide. PMID:23098071

Barnette, Anna L; Kim, Seong H

2012-11-01

399

Structural and Oxidative Changes in the Kidney of Crucian Carp Induced by Silicon-Based Quantum Dots  

PubMed Central

Silicon-based quantum dots were intraperitoneally injected in Carassius auratus gibelio specimens and, over one week, the effects on renal tissue were investigated by following their distribution and histological effects, as well as antioxidative system modifications. After three and seven days, detached epithelial cells from the basal lamina, dilated tubules and debris in the lumen of tubules were observed. At day 7, nephrogenesis was noticed. The reduced glutathione (GSH) concentration decreased in the first three days and started to rise later on. The superoxide dismutase (SOD) activity increased only after one week, whereas catalase (CAT) was up-regulated in a time-dependent manner. The activities of glutathione reductase (GR) and glutathione peroxidise (GPX) decreased dramatically by approximately 50% compared to control, whereas the glutathione-S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH) increased significantly after 3 and 7 days of treatment. Oxidative modifications of proteins and the time-dependent increase of Hsp70 expression were also registered. Our data suggest that silicon-based quantum dots induced oxidative stress followed by structural damages. However, renal tissue is capable of restoring its integrity by nephron development. PMID:22949855

Petrache, Sorina Nicoleta; Stanca, Loredana; Serban, Andreea Iren; Sima, Cornelia; Staicu, Andreia Cristina; Munteanu, Maria Cristina; Costache, Marieta; Burlacu, Radu; Zarnescu, Otilia; Dinischiotu, Anca

2012-01-01

400

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

DOEpatents

A process for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900.degree.-1500.degree. C. and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

Sarin, Vinod K. (Lexington, MA)

1991-01-01

401

Aspects of the magmatic geochemistry of bismuth  

USGS Publications Warehouse

Bismuth has been determined in 74 rocks from a differentiated tholeiitic dolerite, two calc-alkaline batholith suites and in 66 mineral separates from one of the batholiths. Average bismuth contents, weighted for rock type, of the Great Lake (Tasmania) dolerite, the Southern California batholith and the Idaho batholith are, 32, 50 and 70 ppb respectively. All three bodies demonstrate an enrichment of bismuth in residual magmas with magmatic differentiation. Bismuth is greatly enriched (relative to the host rock) in the calcium-rich accessory minerals, apatite and sphene, but other mineral analyses show that a Bi-Ca association is of little significance to the magmatic geochemistry of bismuth. Most of the bismuth, in the Southern California batholith at least, occurs in a trace mineral phase (possibly sulfides) present as inclusions in the rock-forming minerals. ?? 1973.

Greenland, L.P.; Gottfried, D.; Campbell, E.Y.

1973-01-01

402

Loss measurement of oxidized porous silicon optical waveguides by nondestructive end-fire coupling  

NASA Astrophysics Data System (ADS)

The oxidised porous silicon channel waveguides were fabricated by controlling the illumination intensities and anodisation time during anodisation process is reported in this paper. By the technique combined the optimisation end-fire coupling and cut-back methods, the relatively exact results of measured propagation loss, endface' s scattering loss and the mode mismatching loss of oxidised porous silicon channel waveguides were 12.5.2dB/cm, 4.6dB and 3.1dB respectively.

Jia, Zhenhong

2002-08-01

403

Light scattering tomography study of lattice defects in high quality as-grown CZ silicon wafers and their evolution during gate oxidation  

SciTech Connect

Wafers from silicon ingots grown in the vacancy rich regime with different crystal cooling rates have been used for investigations by infrared light scattering tomography (IR-LST), preferential defect etching and gate oxide integrity (GOI) tests. GOI evaluation was done for 6.4 mn and 15 nm gate oxides. A clear correlation is obtained between substrate defects observed by LST and Secco etching after gate oxidation and GOI. In a second experiment the effect of intentional contamination with 10{sup 12} Fe cm{sup -2} before gate oxidation is evaluated.

Vanhellemont, J.; Kenis, K.; Depas, M.; Mertens, P. [IMEC, Leuven (Belgium)] [and others

1996-12-01

404

A scalable silicon microreactor for preferential CO oxidation: performance comparison with a tubular  

E-print Network

technology for the development of compact fuel processing systems as compared to packed-bed reactor with a tubular packed-bed microreactor Sujit Srinivasa , Amit Dhingrab , Hong Imb , Erdogan Gularia obtained from a conventional packed-bed microreactor. The silicon microreactor performs very well, while

Gulari, Erdogan

405

Light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst  

E-print Network

Integrating a silicon solar cell with a recently developed cobalt-based water-splitting catalyst (Co-Pi) yields a robust, monolithic, photo-assisted anode for the solar fuels process of water splitting to O2 at neutral pH. ...

Pijpers, Joep J. H.

406

Oxidation behaviour of Carbon\\/Carbon Composites impregnated with silica and silicon oxycarbide  

Microsoft Academic Search

Carbon\\/Carbon Composites made with high strength carbon fibers as reinforcement and pitch as matrix precursor have been impregnated with silica sol and silicon oxycarbide precursor (in sol form). On subsequent heat treatment to 1000°C and 1600°C, these composites have been found to exhibit slag and glassy coatings. Apparent density of the composites at different stages has been measured by water

L. M. Manocha; S. Manocha; Ketan B. Patel; P. Glogar

2000-01-01

407

Undercooling of bulk liquid silicon in an oxide flux Y. Shao and F. Spaepen  

E-print Network

so far for bulk silicon. To account for this result as well as the nucleation data from laser laser melting7 based on homoge- neous crystal nucleation.8 EXPERIMENTS A suitable flux for undercooling above 1300 °C. The experiments were carried out in a stainless steel chamber. A small Ta box heater

Spaepen, Frans A.

408

A silicon nanowire-reduced graphene oxide composite as a high-performance lithium ion battery anode material  

NASA Astrophysics Data System (ADS)

Toward the increasing demands of portable energy storage and electric vehicle applications, silicon has been emerging as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, serious pulverization of bulk silicon during cycling limits its cycle life. Herein, we report a novel hierarchical Si nanowire (Si NW)-reduced graphene oxide (rGO) composite fabricated using a solvothermal method followed by a chemical vapor deposition process. In the composite, the uniform-sized [111]-oriented Si NWs are well dispersed on the rGO surface and in between rGO sheets. The flexible rGO enables us to maintain the structural integrity and to provide a continuous conductive network of the electrode, which results in over 100 cycles serving as an anode in half cells at a high lithium storage capacity of 2300 mA h g-1. Due to its [111] growth direction and the large contact area with rGO, the Si NWs in the composite show substantially enhanced reaction kinetics compared with other Si NWs or Si particles.Toward the increasing demands of portable energy storage and electric vehicle applications, silicon has been emerging as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, serious pulverization of bulk silicon during cycling limits its cycle life. Herein, we report a novel hierarchical Si nanowire (Si NW)-reduced graphene oxide (rGO) composite fabricated using a solvothermal method followed by a chemical vapor deposition process. In the composite, the uniform-sized [111]-oriented Si NWs are well dispersed on the rGO surface and in between rGO sheets. The flexible rGO enables us to maintain the structural integrity and to provide a continuous conductive network of the electrode, which results in over 100 cycles serving as an anode in half cells at a high lithium storage capacity of 2300 mA h g-1. Due to its [111] growth direction and the large contact area with rGO, the Si NWs in the composite show substantially enhanced reaction kinetics compared with other Si NWs or Si particles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05093a

Ren, Jian-Guo; Wang, Chundong; Wu, Qi-Hui; Liu, Xiang; Yang, Yang; He, Lifang; Zhang, Wenjun

2014-02-01

409

Magnetic resonance observations of defects involved in bias temperature instabilities and stress induced leakage currents in hafnium dioxide and silicon dioxide based metal-oxide-silicon structures  

NASA Astrophysics Data System (ADS)

This study examines underlying physical mechanisms involved in two very important reliability problems in SiO2 based and HfO2 based metal-oxide-silicon technology: the negative bias temperature instability (NBTI) and an important aspect of low-voltage stress induced leakage currents (LV-SILC). A combination of conventional electron spin resonance (ESR), electrically-detected magnetic resonance including spin dependent recombination (SDR) and spin dependent tunneling (SDT), and electrical measurements have been utilized to study variously processed samples in an attempt to understand the specific defects and the roles that they play in these reliability problems. After a brief introduction and background, chapter 3 discusses a newly developed means to perform SDT on ultra-thin oxides which we call energy-resolved spin dependent tunneling and is used to directly determine the energy levels of K centers involved in LV-SILC in nitrided SiO2 devices. In chapter 4, a newly developed ESR technique which we call on-the-fly ESR is utilized to study the triggering mechanisms of NBTI in pure SiO2 devices. Chapter 5 utilizes SDR measurements on SiO2 based structures and attempts to examine the role that fluorine plays in suppressing NBTI in pure SiO2 devices while doing little to suppress NBTI in nitrided SiO 2 devices. Chapter 6 presents a conventional ESR and SDR study which attempts to identify the electronic and physical nature of pre-existing trapping centers in the SiO2 like interfacial layer region of HfO2 based devices which are thought to play important roles in limiting the performance and reliability of these structures.

Ryan, Jason Thomas

410

Critical oxide thickness for efficient single-walled carbon nanotube growth on silicon using thin SiO2 diffusion barriers.  

PubMed

The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand their range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth of single-walled carbon nanotubes on bare silicon and on ultrathin oxides is greatly inhibited due to the formation of a noncatalytic silicide. Using X-ray photoelectron spectroscopy, we show that silicide formation occurs on ultrathin oxides due to thermally activated metal diffusion through the oxide. Silicides affect the growth of single-walled nanotubes more than multi-walled nanotubes due to the increased kinetics at the higher single-walled nanotube growth temperature. We demonstrate that nickel and iron catalysts, when deposited on clean silicon or ultrathin silicon dioxide layers, begin to form silicides at relatively low temperatures, and that by 900 degrees C, all of the catalyst has been incorporated into the silicide, rendering it inactive for subsequent single-walled nanotube growth. We further show that a 4-nm silicon dioxide layer is the minimum diffusion barrier thickness that allows for efficient single-walled nanotube growth. PMID:17193143

Simmons, Jason M; Nichols, Beth M; Marcus, Matthew S; Castellini, Olivia M; Hamers, Robert J; Eriksson, Mark A

2006-07-01

411

Comparison of electric properties of ultra-thin thermal and plasma nitrided silicon oxides with different post-deposition treatments using C-AFM  

Microsoft Academic Search

The electrical quality of ultra-thin (?1nm) Plasma and Thermal nitrided silicon oxide layers was investigated with Conductive AFM and a macroscopic I-V measurement setup. PN layers were found to be superior to TN layers. A longer nitridation time resulted in a better quality of the layer. Annealing in N2 was not beneficial and re-oxidation resulted in a lower leakage due

W. Polspoel; W. Vandervorst; J. Pétry; T. Conard; A. Benedetti

2005-01-01

412

Generation-annealing of interface traps and hydrogenation of boron acceptors in metal-oxide-silicon capacitors irradiated by kilo-volt electrons  

Microsoft Academic Search

Generation and annealing of interface traps and deactivation of boron acceptors in silicon are investigated in Al\\/SiOâ\\/Si capacitors exposed to 8-keV electrons. Post-oxidation conditions are varied. Interface and oxide traps are separated using a repeated stress-anneal technique with the time-dependent high-frequency capacitance-voltage measurements. Two interface trap species were detected in all capacitors. Boron hydrogenation proceeds rapidly during irradiation but continues

Lin; W. W. L

1987-01-01

413

Bis(tri-n-hexylsilyl oxide) silicon phthalocyanine: a unique additive in ternary bulk heterojunction organic photovoltaic devices.  

PubMed

Previous studies have shown that the use of bis(tri-n-hexylsilyl oxide) silicon phthalocyanine ((3HS)2-SiPc) as an additive in a P3HT:PC61BM cascade ternary bulk heterojunction organic photovoltaic (BHJ OPV) device results in an increase in the short circuit current (J(SC)) and efficiency (?(eff)) of up to 25% and 20%, respectively. The previous studies have attributed the increase in performance to the presence of (3HS)2-SiPc at the BHJ interface. In this study, we explored the molecular characteristics of (3HS)2-SiPc which makes it so effective in increasing the OPV device J(SC) and ?(eff. Initially, we synthesized phthalocyanine-based additives using different core elements such as germanium and boron instead of silicon, each having similar frontier orbital energies compared to (3HS)2-SiPc and tested their effect on BHJ OPV device performance. We observed that addition of bis(tri-n-hexylsilyl oxide) germanium phthalocyanine ((3HS)2-GePc) or tri-n-hexylsilyl oxide boron subphthalocyanine (3HS-BsubPc) resulted in a nonstatistically significant increase in JSC and ?(eff). Secondly, we kept the silicon phthalocyanine core and substituted the tri-n-hexylsilyl solubilizing groups with pentadecyl phenoxy groups and tested the resulting dye in a BHJ OPV. While an increase in JSC and ?(eff) was observed at low (PDP)2-SiPc loadings, the increase was not as significant as (3HS)2-SiPc; therefore, (3HS)2-SiPc is a unique additive. During our study, we observed that (3HS)2-SiPc had an extraordinary tendency to crystallize compared to the other compounds in this study and our general experience. On the basis of this observation, we have offered a hypothesis that when (3HS)2-SiPc migrates to the P3HT:PC61BM interface the reason for its unique performance is not solely due to its frontier orbital energies but also might be due to a high driving force for crystallization. PMID:25105425

Lessard, Benoît H; Dang, Jeremy D; Grant, Trevor M; Gao, Dong; Seferos, Dwight S; Bender, Timothy P

2014-09-10

414

Pharmacokinetics of bismuth and ranitidine following multiple doses of ranitidine bismuth citrate  

PubMed Central

The pharmacokinetics of bismuth and ranitidine derived from oral doses of ranitidine bismuth citrate 800 mg given twice daily for 28 days were examined in this double-blind, placebo-controlled, parallel-group study in 27 healthy subjects. Bismuth accumulation in plasma reflected its multicompartmental disposition, achieving the majority of predicted steady state within 14–28 days. Bismuth absorption from ranitidine bismuth citrate is limited (<0.5% of the dose), and bismuth elimination is predominantly renal secretion. Peak plasma concentrations did not exceed 19 ng ml?1, remaining well below those associated with bismuth toxicity. Bismuth was measurable at low concentrations in plasma and urine for up to 5 months after the last dose. Plasma bismuth concentration-time data and urinary excretion data were best described by separate multicompartmental models, with terminal half-lives averaging 21 days and 45 days, respectively. The pharmacokinetics of ranitidine derived from ranitidine bismuth citrate were similar to those of ranitidine administered alone. Ranitidine did not appreciably accumulate in plasma. Ranitidine bismuth citrate was well-tolerated during 28 days of repeated dosing. PMID:8864319

KOCH, K M; KERR, B M; GOODING, A E; DAVIS, I M

1996-01-01

415

Substitution effects on bismuth based multifunctional materials  

NASA Astrophysics Data System (ADS)

Described are our targeted experiments to improve understanding of some key aspects of the mechanisms contributing to intrinsic effects such as the magnetoelectric coupling in oxides. The magnetoelectric materials have long been of interest because of useful combinations of electrical, magnetic, optical and catalytic properties. Particularly spectacular are the manganites(M=Mn) for which apart from the strong magnetoresistance (MR) effect another striking feature is the occurrence of charge and orbital ordering (CO-OO) effects connected with the specific orbital orientation and the spatial arrangement of the eg orbitals. The MR and CO-OO effects are a manifestation of the strong interplay between the orbital, charge, and spin degrees of freedom in these systems and in some cases gives rise to multiferroicity. In this regard, some of our research is on new ABO3, AB2O5 and double perovskites A2BB'O6 containing p elements with lone pair electrons such as Bi3+. Bismuth creates irregular oxygen coordination environment and to stabilize its valence state often requires the use of high pressure or specific soft chemistry. Studied are the effects of cationic substitution on the structural parameters of the perovskites (Bi1-yRy)1-xAxMnO3 (R = rare earth; A= Ca2+, Sr2+; x,y=0.5), BiFexMn2-xO5, La1-xBiXMn2O5 etc. Ab-initio density functional theory calculations were performed to study the structure, magnetic and optical properties of multiferroic BiFeO3, also modified with La3+ and Mn3+. Synthesized and characterized is a new bismuth oxide - multiferroic BiFe2O5-? A number of studies continue to address this class of materials and related-type materials such as cobaltites, chromites and ferrites, much of the work being driven by the potential applications as electrode materials in solid oxide fuel cells, exhaust gas sensors, membranes for separation processes or as catalysts but lately new functionalities emerge and are in the focus for use in electronics and information storage capabilities.

Krezhov, Kiril; Kovachev, Stefan; Svab, Erzsebet

416

Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface  

SciTech Connect

Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important.

Nichau, A.; Schnee, M.; Schubert, J.; Bernardy, P.; Hollaender, B.; Buca, D.; Mantl, S. [Peter Gruenberg Institute 9 (PGI9-IT), Forschungszentrum Juelich, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technologies, 52425 Juelich (Germany); Besmehn, A.; Breuer, U. [Central Division for Chemical Analysis (ZCH), Forschungszentrum Juelich, 52425 Juelich (Germany); Rubio-Zuazo, J.; Castro, G. R. [Spanish CRG BM25 Beamline-SpLine, European Synchrotron Radiation Facility (ESRF), Rue Jules Horowitz BP 220, F-38043 Grenoble, Cedex 09 (France); Muecklich, A.; Borany, J. von [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum' Dresden-Rossendorf e.V., 01314 Dresden (Germany)

2013-04-21

417

The absorption of bismuth and salicylate from oral doses of Pepto-Bismol (bismuth salicylate).  

PubMed

Plasma bismuth and plasma salicylate concentrations were measured before and after three 30-ml oral doses of bismuth salicylate (Pepto-Bismol liquid) in 10 fasting healthy subjects. From 0 to 120 min following the first dose of bismuth salicylate, the plasma bismuth concentration was less than 1 ng/ml. The peak median plasma bismuth concentration was at +240 min (1.7 ng/ml; range 0.8-5.3 ng/ml). Salicylate appeared in the plasma of all subjects at +30 min, and it reached a peak at +120 min (median 61 mg/L; range 46-104 mg/L). The study demonstrates that, despite rapid and substantial absorption of salicylate, there is negligible absorption of bismuth into the bloodstream from standard oral doses of bismuth salicylate. PMID:2104082

Nwokolo, C U; Mistry, P; Pounder, R E

1990-04-01

418

Coulomb oscillations based on band-to-band tunneling in a degenerately doped silicon metal-oxide-semiconductor field-effect transistor  

E-print Network

an impurity potential, such as local- ized electron states or trapped charge,5,6 were reported in moderately or silicon film,9 and pattern deformation and band-profile modification due to oxide-induced stress.10 These mechanisms were based on un- doped Si in order to prevent the unintentional characteristics due to impurity

Lee, Jong Duk

419

Investigating the addition of silicon oxide to carbon: Effects of amount and heat treatment on anti-aggregation and electrochemical performance of Pt catalysts  

Microsoft Academic Search

Small nanoparticles offer high surface areas and are certainly desirable for electrocatalytic reactions and fuel cells. However, the drawback of using small nanoparticles is their tendency towards particle aggregation. This paper aims to inhibit platinum agglomeration by adding silicon oxide to a carbon support for enhanced catalytic activity in low-temperature fuel cells. The catalysts are characterized by X-ray diffraction and

Yan-Ni Wu; Shi-Jun Liao; Jian-Huang Zeng

2011-01-01

420

Influence of Alumina Reaction Tube Impurities on the Oxidation of Chemically-Vapor-Deposited Silicon Carbide  

NASA Technical Reports Server (NTRS)

Pure coupons of chemically vapor deposited (CVD) SiC were oxidized for 100 h in dry flowing oxygen at 1300 C. The oxidation kinetics were monitored using thermogravimetry (TGA). The experiments were first performed using high-purity alumina reaction tubes. The experiments were then repeated using fused quartz reaction tubes. Differences in oxidation kinetics, scale composition, and scale morphology were observed. These differences were attributed to impurities in the alumina tubes. Investigators interested in high-temperature oxidation of silica formers should be aware that high-purity alumina can have significant effects on experiment results.

Opila, Elizabeth

1995-01-01

421

Statistical Analysis of Subthreshold Swing in Fully Depleted Silicon-on-Thin-Buried-Oxide and Bulk Metal-Oxide-Semiconductor Field Effect Transistors  

NASA Astrophysics Data System (ADS)

The variability of subthreshold swing (SS) in fully depleted (FD) silicon-on-thin-buried-oxide (SOTB) MOSFETs is statistically analyzed and compared with that of conventional bulk MOSFETs. It is newly found that SS variability is small enough in deep subthreshold region (small drain current Ids) while it increases as increasing Ids. The mechanisms of this behavior is intensively investigated and it is found that the increase in SS variability is caused by current-onset voltage (COV) variability that is due to random dopant fluctuation (RDF). Since SOTB FETs have small COV variability thanks to an intrinsic channel, SS variability is much smaller than bulk FETs, which is a great advantage of FD SOTB in terms of Ion/Ioff ratio.

Mizutani, Tomoko; Yamamoto, Yoshiki; Makiyama, Hideki; Iwamatsu, Toshiaki; Oda, Hidekazu; Sugii, Nobuyuki; Hiramoto, Toshiro

2013-04-01

422

Modification of optical and electrical properties of zinc oxide-coated porous silicon nanostructures induced by swift heavy ion  

PubMed Central

Morphological and optical characteristics of radio frequency-sputtered zinc aluminum oxide over porous silicon (PS) substrates were studied before and after irradiating composite films with 130?MeV of nickel ions at different fluences varying from 1?×?1012 to 3?×?1013 ions/cm2. The effect of irradiation on the composite structure was investigated by scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence spectroscopy. Current–voltage characteristics of ZnO-PS heterojunctions were also measured. As compared to the granular crystallites of zinc oxide layer, Al-doped zinc oxide (ZnO) layer showed a flaky structure. The PL spectrum of the pristine composite structure consists of the emission from the ZnO layer as well as the near-infrared emission from the PS substrate. Due to an increase in the number of deep-level defects, possibly oxygen vacancies after swift ion irradiation, PS-Al-doped ZnO nanocomposites formed with high-porosity PS are shown to demonstrate a broadening in the PL emission band, leading to the white light emission. The broadening effect is found to increase with an increase in the ion fluence and porosity. XRD study revealed the relative resistance of the film against the irradiation, i.e., the irradiation of the structure failed to completely amorphize the structure, suggesting its possible application in optoelectronics and sensing applications under harsh radiation conditions. PMID:22748164

2012-01-01

423

Hydrogen-terminated silicon nanowire photocatalysis: Benzene oxidation and methyl red decomposition  

SciTech Connect

Graphical abstract: H-SiNWs can catalyze hydroxylation of benzene and degradation of methyl red under visible light irradiation. Highlights: Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were active photocatalyst in the hydroxylation of benzene under light. Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were also effective in the decomposition of methyl red dye. Black-Right-Pointing-Pointer The Si/SiO{sub x} core-shell structure is the main reason of the obtained high selectivity during the hydroxylation. -- Abstract: Hydrogen-terminated silicon nanowires (H-SiNWs) were used as heterogeneous photocatalysts for the hydroxylation of benzene and for the decomposition of methyl red under visible light irradiation. The above reactions were monitored by GC-MS and UV-Vis spectrophotometry, respectively, which shows 100% selectivity for the transformation of benzene to phenol. A complete decomposition of a 2 Multiplication-Sign 10{sup -4} M methyl red solution was achieved within 30 min. The high selectivity for the hydroxylation of benzene and the photodecomposition demonstrate the catalytic activity of ultrafine H-SiNWs during nanocatalysis.

Lian, Suoyuan [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); School of Chemical Engineering and Materials, Dalian Polytechnic University, Dalian 116034 (China); Tsang, Chi Him A. [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)] [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)] [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Wong, Ningbew [Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China)] [Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Lee, Shuit-Tong [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China)

2011-12-15

424

Sintered-reaction Bonded Silicon Nitride Densified by a Gas Pressure Sintering Process Effects of Rare Earth Oxide Sintering Additives  

SciTech Connect

Reaction-bonded silicon nitrides containing rare-earth oxide sintering additives were densified by gas pressure sintering. The sintering behavior, microstructure and mechanical properties of the resultant specimens were analyzed. For that purpose, Lu2O3-SiO2 (US), La2O3-MgO (AM) and Y2O3-Al2O3 (YA) additive systems were selected. Among the tested compositions, densification of silicon nitride occurred at the lowest temperature when using the La2O3-MgO system. Since the Lu2O3-SiO2 system has the highest melting temperature, full densification could not be achieved after sintering at 1950oC. However, the system had a reasonably high bending strength of 527 MPa at 1200oC in air and a high fracture toughness of 9.2 MPa m1/2. The Y2O3-Al2O3 system had the highest room temperature bending strength of 1.2 GPa

Lee, S. H. [Korea Institute of Materials Science; Ko, J. W. [Korea Institute of Materials Science; Park, Y. J. [Korea Institute of Materials Science; Kim, H. D. [Korea Institute of Materials Science; Lin, Hua-Tay [ORNL; Becher, Paul F [ORNL

2012-01-01

425

The feasibility of using molten carbonate corrosion for separating a nuclear surrogate for plutonium oxide from silicon carbide inert matrix  

NASA Astrophysics Data System (ADS)

Silicon carbide is one of the prime candidates as a matrix material in inert matrix fuels (IMF) being designed to reduce the plutonium inventories. Since complete fission and transmutation is not practical in a single in-core run, it is necessary to separate the non-transmuted actinide materials from the silicon carbide matrix for recycling. In this work, SiC was corroded in sodium carbonate (Na 2CO 3) and potassium carbonate (K 2CO 3), to form water soluble sodium or potassium silicate. Separation of the transuranics was achieved by dissolving the SiC corrosion product in boiling water. Ceria (CeO 2), which was used as a surrogate for plutonium oxide (PuO 2), was not corroded in these molten salt environments. The molten salt depth, which is a distance between the salt/air interface to the upper surface of SiC pellets, significantly affected the rate of corrosion. The corrosion was faster in K 2CO 3 than in Na 2CO 3 molten salt at 1050 °C, when the initial molten salt depths were kept the same for both salts.

Cheng, Ting; Baney, Ronald H.; Tulenko, James

2010-10-01

426

Quantitative Real-Time Measurements of DNA Hybridization with Alkylated Non-Oxidized Silicon Nanowires in Electrolyte Solution  

PubMed Central

The quantitative, real time detection of single stranded oligonucleotides with silicon nanowires (SiNWs) in physiologically relevant electrolyte solution is demonstrated. Debye screening of the hybridization event is minimized by utilizing electrostatically adsorbed primary DNA on an amine-terminated NW surface. Two surface functionalization chemistries are compared: an amine terminated siloxane monolayer on the native SiO2 surface of the SiNW, and an amine terminated alkyl monolayer grown directly on a hydrogen-terminated SiNW surface. The SiNWs without the native oxide exhibit improved solution-gated field-effect transistor characteristics and a significantly enhanced sensitivity to single stranded DNA detection, with an accompanying two orders of magnitude improvement in the dynamic range of sensing. A model for the detection of analyte by SiNW sensors is developed and utilized to extract DNA binding kinetic parameters. Those values are directly compared with values obtained by the standard method of surface plasmon resonance (SPR), and demonstrated to be similar. The nanowires, however, are characterized by higher detection sensitivity. The implication is that Si NWs can be utilized to quantitate the solution phase concentration of biomolecules at low concentrations. This work also demonstrates the importance of surface chemistry for optimizing biomolecular sensing with silicon nanowires. PMID:17165787

Bunimovich, Yuri L.; Shin, Young Shik; Yeo, Woon-Seok; Amori, Michael; Kwong, Gabriel

2013-01-01

427

Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide-semiconductor-compatible silicon nanowires  

NASA Astrophysics Data System (ADS)

Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide- semiconductor-compatible silicon nanowires (SiNWs) with crown ethers covalently immobilized on their surface are presented. A densely packed organic monolayer terminated with amine groups is introduced to the SiNW surface via hydrosilylation. Amine-modified crown ethers, acting as sensing elements, are then immobilized onto the SiNWs through a cross-linking reaction with the monolayer. The crown ether-functionalized SiNWs recognize Na+ and K+ according to their complexation ability to the crown ethers. The SiNW sensors are highly selective and capable of achieving an ultralow detection limit down to 50nM, over three orders of magnitude lower than that of conventional crown ether-based ion-selective electrodes.

Zhang, Guo-Jun; Agarwal, Ajay; Buddharaju, Kavitha D.; Singh, Navab; Gao, Zhiqiang

2007-06-01

428

Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry  

NASA Astrophysics Data System (ADS)

We present transport measurements of a tunable silicon metal- oxide-semiconductor double quantum dot device with lateral geometry. Experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. Comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling. This work was supported by the LDRD program at Sandia National Laboratories, a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary Lockheed-Martin Company, for the U. S. DOE NNSA under Contract No. DE-AC04-94AL85000

Tracy, L. A.; Young, R. W.; Ten Eyck, G. A.; Eng, K.; Childs, K. D.; Wendt, J. R.; Grubbs, R. K.; Stevens, J.; Lilly, M. P.; Carroll, M. S.; Nordberg, E. P.; Borras Pinilla, C.; Stalford, H. L.; Eriksson, M. A.

2011-03-01

429

Schottky barrier height reduction for holes by Fermi level depinning using metal/nickel oxide/silicon contacts  

NASA Astrophysics Data System (ADS)

We report the experimental demonstration of Fermi level depinning using nickel oxide (NiO) as the insulator material in metal-insulator-semiconductor (M-I-S) contacts. Using this contact, we show less than 0.1 eV barrier height for holes in platinum/NiO/silicon (Pt/NiO/p-Si) contact. Overall, the pinning factor was improved from 0.08 (metal/Si) to 0.26 (metal/NiO/Si). The experimental results show good agreement with that obtained from theoretical calculation. NiO offers high conduction band offset and low valence band offset with Si. By reducing Schottky barrier height, this contact can be used as a carrier selective contact allowing hole transport but blocking electron transport, which is important for high efficiency in photonic applications such as photovoltaics and optical detectors.

Islam, Raisul; Shine, Gautam; Saraswat, Krishna C.

2014-11-01

430

Metal Schottky Source/Drain Technology for Ultrathin Silicon-on-Thin-Box Metal Oxide Semiconductor Field Effect Transistors  

NASA Astrophysics Data System (ADS)

This paper reports novel, non-epitaxial raised source/drain (S/D) approaches to decrease the parasitic external resistance in complementary metal-oxide-semiconductor field-effect transistors (CMOSFETs) fabricated on ultrathin silicon on insulator (UTSOI). This technique utilizes a metal Schottky S/D process with dopant segregation. Selectively formed NiSi2 with dopant segregation fabricated by laser-spike annealing (LSA) significantly lowered effective Shottky-barrier height and, thereby, lowered contact resistance (?c). Satisfying the requirements of UTSOI MOSFETs in the 32-nm node for low stand-by power (LSTP) application, external parasitic resistance was reduced to 140 (NMOS) and 350 (PMOS) ? µm. Our results show that ?c is an important component of parasitic resistance in terms of improving device performance of UTSOI MOSFETs.

Shima, Akio; Sugii, Nobuyuki; Mise, Nobuyuki; Hisamoto, Digh; Takeda, Ken-ichi; Torii, Kazuyoshi

2011-04-01

431

Energy transfer from luminescent centers to Er3+ in erbium-doped silicon-rich oxide films  

PubMed Central

The energy transfer mechanism between luminescent centers (LCs) and Er3+ in erbium-doped silicon-rich oxide (SROEr) films prepared by electron beam evaporation is investigated. Intense photoluminescence of the LCs (weak oxygen bonds, neutral oxygen vacancies, and Si=O states) within the active matrixes is obtained. Fast energy transfer from Si=O states to Er3+ takes advantage in the SROEr film and enhances the light emission from Er3+. The introduction of Si nanoclusters, which induces the Si=O states and facilitates the photon absorption of the Si=O states, is essential to obtain intense photoluminescence from both Si=O states and Er3+. PMID:23981444

2013-01-01

432

Elastoresistance Effects in Evaporated Bismuth Films  

Microsoft Academic Search

For the purpose to use bismuth films as strain gauges or strain transducers, about one hundred bismuth films were evaporated onto glass substrates in an ultra-high vacuum under various conditions, and their characteristics were measured. In carrying out measurements of the change in resistance with mechanical stress or strain (piezo- or elasto-resistance effect), the glass substrate was supported in the

Ryutaro Koike; Hiroyuki Kurokawa

1966-01-01

433

Trends in the Usage of Bismuth.  

National Technical Information Service (NTIS)

Bismuth is obtained largely as a by-product from the ores of other metals, principally copper and lead. Its availability is greatly dependent on demand for the ores of metals with which it is associated. The principal uses for bismuth are in low melting a...

1970-01-01

434

OXIDATION-INDUCED CHANGES IN MECHANICAL PROPERTIES OF SILICON NITRIDE CERAMICS  

E-print Network

that the fracture toughness decreases during oxidation at 1000°C. Reduction of the elastic modulus of the materials nitride ceramics is investigated. The strength and the elastic modulus of the whole material and the hardness, the fracture toughness and the elastic modulus of the internal region (without surface oxide

Gubicza, Jenõ

435

Epitaxial liftoff of thin oxide layers: Yttrium iron garnets onto GaAs  

NASA Astrophysics Data System (ADS)

We report on the implementation of epitaxial liftoff in magnetic garnets. Deep-ion implantation is used to create a buried sacrificial layer in single-crystal yttrium iron garnet (YIG) and bismuth-substituted YIG epilayers grown on gadolinium gallium garnet. The damage generated by the implantation induces a large etch selectivity between the sacrificial layer and the rest of the garnet. 10-?m-thick films of excellent quality are lifted off and bonded to silicon and GaAs substrates. No noticeable degradation in magnetic coercivity due to domain pinning is observed. Stress-induced microfracturing in the thin oxide layers is also addressed.

Levy, M.; Osgood, R. M., Jr.; Kumar, A.; Bakhru, H.

1997-11-01

436

Electrodeposition of molten silicon  

DOEpatents

Silicon dioxide is dissolved in a molten electrolytic bath, preferably comprising barium oxide and barium fluoride. A direct current is passed between an anode and a cathode in the bath to reduce the dissolved silicon dioxide to non-alloyed silicon in molten form, which is removed from the bath.

De Mattei, Robert C. (Sunnyvale, CA); Elwell, Dennis (Palo Alto, CA); Feigelson, Robert S. (Saratoga, CA)

1981-01-01

437

Thickness of surface thin oxide layers determined by impedance spectroscopy using silicon/oxide/electrolyte (SOE) structures  

NASA Astrophysics Data System (ADS)

The differential capacitance of SiO 2 ultra-thin layers on Si substrate is greatly sensitive to the space charge generated within the semiconductor. In the potential scan, the determination of the capacitance/voltage characteristics in MOS devices is hindered by the high value of the tunneling leakage current. In this work, the difficulty was overcome by careful measurement of the impedance diagrams using a semiconductor/oxide/electrolyte (SOE) structure, under zero current flow. Depending on the bias potential we obtained RC equivalent circuits corresponding either to the depletion layer or to the oxide dielectric film. A novel aspect of the work is that both R and C components were derived from the data processing. In a previous work the investigation was focussed on the depletion layer, and lead to values of the resistance term in the range of a few k? to a few M? cm 2, while the capacitance value was a few 10 -2 ?F cm -2. These results were consistent with a theoretical treatment of the bias voltage dependence of the charge distribution near the flatband potential, and constitute a new technique for the determination of the fb potential versus a reference electrode. The present work is devoted to the electrical properties of the Si surface oxide layer. The leakage resistance term of the thermal oxide layer, a few nm thick, was found equal to several 10 8 ? cm 2. But, the electric field within the semiconductor is not effective for the full charge of the oxide capacitance even when the polarization creates an accumulation layer. In accordance with the computed electric field within the semiconductor, the right value of the capacitance can be reached easily when the wafer is submitted to light radiation and provided the polarization of the substrate is such as to generate an inversion layer. This property leads to an accurate method for ultra-thin insulators characterization excluding tunnel leakage current.

Chemla, M.; Bertagna, V.; Erre, R.; Rouelle, F.; Petitdidier, S.; Levy, D.

2004-04-01

438

Electrical and elastoresistance properties of evaporated thin films of bismuth  

E-print Network

405 Electrical and elastoresistance properties of evaporated thin films of bismuth M. Saleh, J pour rendre les couches de bismuth utilisables en tant que jauges de contrainte n'apporte aucune modification majeure des propriétés électriques du bismuth si on les compare à celles des couches de bismuth

Boyer, Edmond

439

Intersubband transitions in bismuth nanowires M. R. Blacka)  

E-print Network

Intersubband transitions in bismuth nanowires M. R. Blacka) Department of Electrical Engineering of an intersubband transition in bismuth nanowires is reported. The previously observed strong absorption in bismuth transitions in bismuth nanowires as a way of building this understanding. When the sample size is smaller than

Cronin, Steve

440

A complex study of the fast blue luminescence of oxidized silicon nanocrystals: the role of the core  

NASA Astrophysics Data System (ADS)

Silicon nanocrystals (SiNCs) smaller than 5 nm are a material with strong visible photoluminescence (PL). However, the physical origin of the PL, which, in the case of oxide-passivated SiNCs, is typically composed of a slow-decaying red-orange band (S-band) and of a fast-decaying blue-green band (F-band), is still not fully understood. Here we present a physical interpretation of the F-band origin based on the results of an experimental study, in which we combine temperature (4-296 K), temporally (picosecond resolution) and spectrally resolved luminescence spectroscopy of free-standing oxide-passivated SiNCs. Our complex study shows that the F-band red-shifts only by 35 meV with increasing temperature, which is almost 6 times less than the red-shift of the S-band in a similar temperature range. In addition, the F-band characteristic decay time obtained from a stretched-exponential fit decreases only slightly with increasing temperature. These data strongly suggest that the F-band arises from the core-related quasi-direct radiative recombination governed by slowly thermalizing photoholes.Silicon nanocrystals (SiNCs) smaller than 5 nm are a material with strong visible photoluminescence (PL). However, the physical origin of the PL, which, in the case of oxide-passivated SiNCs, is typically composed of a slow-decaying red-orange band (S-band) and of a fast-decaying blue-green band (F-band), is still not fully understood. Here we present a physical interpretation of the F-band origin based on the results of an experimental study, in which we combine temperature (4-296 K), temporally (picosecond resolution) and spectrally resolved luminescence spectroscopy of free-standing oxide-passivated SiNCs. Our complex study shows that the F-band red-shifts only by 35 meV with increasing temperature, which is almost 6 times less than the red-shift of the S-band in a similar temperature range. In addition, the F-band characteristic decay time obtained from a stretched-exponential fit decreases only slightly with increasing temperature. These data strongly suggest that the F-band arises from the core-related quasi-direct radiative recombination governed by slowly thermalizing photoholes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06454a

Ondi?, Lukáš; K?sová, Kate?ina; Ziegler, Marc; Fekete, Ladislav; Gärtnerová, Viera; Cháb, Vladimír; Holý, Václav; Cibulka, Ond?ej; Herynková, Kate?ina; Gallart, Mathieu; Gilliot, Pierre; Hönerlage, Bernd; Pelant, Ivan

2014-03-01