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We encourage you to perform a real-time search of NLEBeta
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1

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

Bilayer Graphene Gets a Bandgap Bilayer Graphene Gets a Bandgap Bilayer Graphene Gets a Bandgap Print Wednesday, 26 August 2009 00:00 Graphene is the two-dimensional crystalline form of carbon whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But without a bandgap, graphene's promise can't be realized. As with monolayer graphene, bilayer graphene also has a zero bandgap and thus behaves like a metal. But a bandgap can be introduced if an electric displacement field is applied to the two layers; the material then behaves like a semiconductor. A team of researchers from Berkeley has engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 meV. With precision control of its bandgap over a wide range, plus independent manipulation of its electronic states through electrical doping, dual-gated bilayer graphene becomes a remarkably flexible tool for nanoscale electronic devices.

2

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

Bilayer Graphene Gets a Bandgap Bilayer Graphene Gets a Bandgap Bilayer Graphene Gets a Bandgap Print Wednesday, 26 August 2009 00:00 Graphene is the two-dimensional crystalline form of carbon whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But without a bandgap, graphene's promise can't be realized. As with monolayer graphene, bilayer graphene also has a zero bandgap and thus behaves like a metal. But a bandgap can be introduced if an electric displacement field is applied to the two layers; the material then behaves like a semiconductor. A team of researchers from Berkeley has engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 meV. With precision control of its bandgap over a wide range, plus independent manipulation of its electronic states through electrical doping, dual-gated bilayer graphene becomes a remarkably flexible tool for nanoscale electronic devices.

3

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

Bilayer Graphene Gets a Bandgap Print Bilayer Graphene Gets a Bandgap Print Graphene is the two-dimensional crystalline form of carbon whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But without a bandgap, graphene's promise can't be realized. As with monolayer graphene, bilayer graphene also has a zero bandgap and thus behaves like a metal. But a bandgap can be introduced if an electric displacement field is applied to the two layers; the material then behaves like a semiconductor. A team of researchers from Berkeley has engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 meV. With precision control of its bandgap over a wide range, plus independent manipulation of its electronic states through electrical doping, dual-gated bilayer graphene becomes a remarkably flexible tool for nanoscale electronic devices.

4

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

Bilayer Graphene Gets a Bandgap Print Bilayer Graphene Gets a Bandgap Print Graphene is the two-dimensional crystalline form of carbon whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But without a bandgap, graphene's promise can't be realized. As with monolayer graphene, bilayer graphene also has a zero bandgap and thus behaves like a metal. But a bandgap can be introduced if an electric displacement field is applied to the two layers; the material then behaves like a semiconductor. A team of researchers from Berkeley has engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 meV. With precision control of its bandgap over a wide range, plus independent manipulation of its electronic states through electrical doping, dual-gated bilayer graphene becomes a remarkably flexible tool for nanoscale electronic devices.

5

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

Bilayer Graphene Gets a Bandgap Print Bilayer Graphene Gets a Bandgap Print Graphene is the two-dimensional crystalline form of carbon whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But without a bandgap, graphene's promise can't be realized. As with monolayer graphene, bilayer graphene also has a zero bandgap and thus behaves like a metal. But a bandgap can be introduced if an electric displacement field is applied to the two layers; the material then behaves like a semiconductor. A team of researchers from Berkeley has engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 meV. With precision control of its bandgap over a wide range, plus independent manipulation of its electronic states through electrical doping, dual-gated bilayer graphene becomes a remarkably flexible tool for nanoscale electronic devices.

6

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

Bilayer Graphene Gets a Bandgap Print Bilayer Graphene Gets a Bandgap Print Graphene is the two-dimensional crystalline form of carbon whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. But without a bandgap, graphene's promise can't be realized. As with monolayer graphene, bilayer graphene also has a zero bandgap and thus behaves like a metal. But a bandgap can be introduced if an electric displacement field is applied to the two layers; the material then behaves like a semiconductor. A team of researchers from Berkeley has engineered a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 meV. With precision control of its bandgap over a wide range, plus independent manipulation of its electronic states through electrical doping, dual-gated bilayer graphene becomes a remarkably flexible tool for nanoscale electronic devices.

7

Origin of ferromagnetism enhancement in bi-layer chromium-doped indium zinc oxides  

SciTech Connect

This work demonstrates that by controlling the rapid thermal annealing temperature, amorphous chromium-doped indium zinc oxide films develop an amorphous-crystalline bi-layer structure and show magnetization up to {approx}30 emu/cm{sup 3}. The crystalline layer arises from significant out-diffusion of Zn from surfaces, leading to a large difference in the Zn:In ratio in amorphous and crystalline layers. Doped Cr ions in amorphous and crystalline layers form different valence configurations, creating a charge reservoir which transfers electrons through amorphous-crystalline interfaces and in turn enhances ferromagnetism.

Hsu, C. Y. [Physics Department, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China)

2012-08-06T23:59:59.000Z

8

Optical Determination of Gate--Tunable Bandgap in Bilayer Graphene  

Science Conference Proceedings (OSTI)

The electronic bandgap is an intrinsic property of semiconductors and insulators that largely determines their transport and optical properties. As such, it has a central role in modern device physics and technology and governs the operation of semiconductor devices such as p-n junctions, transistors, photodiodes and lasers. A tunable bandgap would be highly desirable because it would allow great flexibility in design and optimization of such devices, in particular if it could be tuned by applying a variable external electric field. However, in conventional materials, the bandgap is fixed by their crystalline structure, preventing such bandgap control. Here we demonstrate the realization of a widely tunable electronic bandgap in electrically gated bilayer graphene. Using a dual-gate bilayer graphene field-effect transistor (FET) and infrared microspectroscopy, we demonstrate a gate-controlled, continuously tunable bandgap of up to 250 meV. Our technique avoids uncontrolled chemical doping and provides direct evidence of a widely tunable bandgap -- spanning a spectral range from zero to mid-infrared -- that has eluded previous attempts. Combined with the remarkable electrical transport properties of such systems, this electrostatic bandgap control suggests novel nanoelectronic and nanophotonic device applications based on graphene.

Zhang, Yuanbo; Tang, Tsung-Ta; Girit, Caglar; Hao, Zhao; Martin, Michael C.; Zettl, Alex; Crommie, Michael F.; Shen, Y. Ron; Wang, Feng

2009-08-11T23:59:59.000Z

9

Lipid bilayers on nano-templates  

DOE Patents (OSTI)

A lipid bilayer on a nano-template comprising a nanotube or nanowire and a lipid bilayer around the nanotube or nanowire. One embodiment provides a method of fabricating a lipid bilayer on a nano-template comprising the steps of providing a nanotube or nanowire and forming a lipid bilayer around the polymer cushion. One embodiment provides a protein pore in the lipid bilayer. In one embodiment the protein pore is sensitive to specific agents

Noy, Aleksandr (Belmont, CA); Artyukhin, Alexander B. (Menlo Park, CA); Bakajin, Olgica (San Leandro, CA); Stoeve, Pieter (Davis, CA)

2009-08-04T23:59:59.000Z

10

Band Structure Asymmetry of Bilayer Graphene Revealed by Infrared Spectroscopy  

Science Conference Proceedings (OSTI)

We report on infrared spectroscopy of bilayer graphene integrated in gated structures. We observe a significant asymmetry in the optical conductivity upon electrostatic doping of electrons and holes. We show that this finding arises from a marked asymmetry between the valence and conduction bands, which is mainly due to the inequivalence of the two sublattices within the graphene layer and the next-nearest-neighbor interlayer coupling. From the conductivity data, the energy difference of the two sublattices and the interlayer coupling energy are directly determined.

Li, Z.Q.; Henriksen, E.A.; Jiang, Z.; Hao, Zhao; Martin, Michael C.; Kim, P.; Stormer, H.L.; Basov, Dimitri N.

2008-12-10T23:59:59.000Z

11

Transverse electric plasmons in bilayer graphene  

E-Print Network (OSTI)

We predict the existence of transverse electric (TE) plasmons in bilayer graphene. We find that their plasmonic properties are much more pronounced in bilayer than in monolayer graphene, in a sense that they can get more ...

Jablan, Marinko

12

STABLE HIGH CONDUCTIVITY BILAYERED ELECTROLYTES FOR LOW TEMPERATURE SOLID OXIDE FUEL CELLS  

DOE Green Energy (OSTI)

A bilayer electrolyte consisting of acceptor-doped ceria (on the fuel/reducing side) and cubic-stabilized bismuth oxide (on the oxidizing side) was developed. The bilayer electrolyte that was developed showed significant improvement in open-circuit potential versus a typical ceria based SOFC. Moreover, the OCP of the bilayer cells increased as the thickness of the bismuth oxide layer increased relative to the ceria layer. Thereby, verifying the bilayer concept. Although, because of the absence of a suitable cathode (a problem we are still working assiduously to solve), we were unable to obtain power density curves, our modeling work predicts a reduction in electrolyte area specific resistance of two orders of magnitude over cubic-stabilized zirconia and projects a maximum power density of 9 W/m{sup 2} at 800 C and 0.09 W/m{sup 2} at 500 C. Towards the development of the bilayer electrolyte other significant strides were made. Among these were, first, the development of a, bismuth oxide based, oxide ion conductor with the highest conductivity (0.56 S/cm at 800 C and 0.043 S/cm at 500 C) known to date. Second, a physical model of the defect transport mechanisms and the driving forces for the ordering phenomena in bismuth oxide and other fluorite systems was developed. Third, a model for point defect transport in oxide mixed ionic-electronic conductors was developed, without the typical assumption of a uniform distribution of ions and including the effect of variable loads on the transport properties of an SOFC (with either a single or bilayer electrolyte).

Eric D. Wachsman; Keith L. Duncan

2002-09-30T23:59:59.000Z

13

"Nanocrystal bilayer for tandem catalysis"  

DOE Green Energy (OSTI)

Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

2011-01-24T23:59:59.000Z

14

Probing Membrane Protein Dimerization in the Native Bilayer ...  

Science Conference Proceedings (OSTI)

... Native Bilayer Environment. Kalina Hristova, Department of Materials Science and Engineering Johns Hopkins University. ...

15

Structure and Orientational Texture of Self-Organizing Lipid Bilayers  

Science Conference Proceedings (OSTI)

The structure of single supported dipalmitoyl-phosphatidylcholine bilayers prepared by vesicle fusion or Langmuir-Blodgett-Schaeffer (LBS) deposition techniques was characterized by x-ray reflectivity and grazing incidence diffraction in bulk water. LBS bilayers display symmetric leaflets similar to monolayer structures, while vesicle fusion yields more inhomogeneous bilayers. Diffraction establishes that lipids are always coupled across the bilayer even when leaflets are deposited independently and suggests the existence of orientational texture.

Watkins, E. B. [Biophysics Graduate Group, University of California, Davis, California 95616 (United States); Manuel Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States); Miller, C. E.; Majewski, J. [Manuel Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States); Mulder, D. J. [Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616 (United States); Kuhl, T. L. [Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616 (United States); Department of Biomedical Engineering, University of California, Davis, California 95616 (United States)

2009-06-12T23:59:59.000Z

16

Magnetic properties of TM/RE bilayer thin films  

Science Conference Proceedings (OSTI)

... Magnetic properties of TM/RE bilayer thin films. I. Zoto University of Alabama. The magnetic recording technology badly ...

17

Spin precession modulation in a magnetic bilayer  

Science Conference Proceedings (OSTI)

We report on modulation of the spin precession in a Co/garnet bilayer by femtosecond laser excitation using time-resolved magneto-optical tools. Damped oscillations in the Faraday rotation transients representing precessional motion of the magnetization vector are observed in both the 2 nm Co layer and 1.8 {mu}m garnet of the bilayer with distinct frequencies differing by about a factor of two. The excitation efficiency of these precessions strongly depends on the out-of-plane magnetic field. The modulation effect with the coupling in a magnetic bilayer can be useful for non-thermally controlling the magnetization of nanomagnets and ultrafast switching in magnetic nanodevices.

Stupakiewicz, A.; Maziewski, A. [Laboratory of Magnetism, Faculty of Physics, University of Bialystok, Lipowa 41, Bialystok (Poland); Pashkevich, M. [Laboratory of Magnetism, Faculty of Physics, University of Bialystok, Lipowa 41, Bialystok (Poland); Scientific-Practical Materials Research Centre of the NASB, P. Brovki 19, Minsk (Belarus); Stognij, A.; Novitskii, N. [Scientific-Practical Materials Research Centre of the NASB, P. Brovki 19, Minsk (Belarus)

2012-12-24T23:59:59.000Z

18

Collective Excitations in Electron-Hole Bilayers  

Science Conference Proceedings (OSTI)

We report a combined analytic and molecular dynamics analysis of the collective mode spectrum of a bipolar (electron-hole) bilayer in the strong coupling classical limit. A robust, isotropic energy gap is identified in the out-of-phase spectra, generated by the combined effect of correlations and of the excitation of the bound dipoles. In the in-phase spectra we identify longitudinal and transverse acoustic modes wholly maintained by correlations. Strong nonlinear generation of higher harmonics of the fundamental dipole oscillation frequency and the transfer of harmonics between different modes is observed.

Kalman, G. J. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Hartmann, P.; Donko, Z. [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Golden, K. I. [Department of Mathematics and Statistics and Department of Physics, University of Vermont, Burlington, Vermont 05401 (United States)

2007-06-08T23:59:59.000Z

19

Performance of Anode-Supported Solid Oxide Fuel Cell with Thin Bi-Layer Electrolyte by Pulsed Laser Deposition  

Science Conference Proceedings (OSTI)

Anode-supported yttria stabilized zirconia (YSZ)/samaria doped ceria (SDC) bi-layer electrolytes with uniform thickness and high density were fabricated by pulsed laser deposition at 1000 degrees C. Fuel cells with such bi-layer electrolytes were fabricated and tested, yielding open circuit voltages from 0.94 to 1.0 V at 600-700 degrees C. Power densities from 0.4 to 1.0 W cm{sup -2} at 0.7 V were achieved in air at temperatures of 600-700 degrees C. Cell performance was improved in flowing oxygen, with an estimated peak power density of over 2 W cm{sup -2} at 650 degrees C, assuming the same overall resistance over the entire range of current density. The high cell performance was attributed to the very low ohmic resistance of the fuel cell, owing to the small thickness of the electrolyte. Stable performance was also demonstrated in that the voltage of the fuel cell showed very little change at a constant current density of 1 A cm{sup -2} during more than 400 hours of operation at 650 degrees C in flowing oxygen. SEM analysis of the fuel cell after testing showed that the bi-layer electrolyte had retained its chemical and mechanical integrity.

Lu, Zigui; Hardy, John S.; Templeton, Jared W.; Stevenson, Jeffry W.; Fisher, Daniel; Wu, Naijuan; Ignatiev, Alex

2012-07-15T23:59:59.000Z

20

Collective Dynamics of Complex Plasma Bilayers  

Science Conference Proceedings (OSTI)

A classical dusty plasma experiment was performed using two different dust grain sizes to form a strongly coupled asymmetric bilayer (two closely spaced interacting monolayers) of two species of charged dust particles. The observation and analysis of the thermally excited particle oscillations revealed the collective mode structure and dispersion (wave propagation) in this system; in particular, the existence of the theoretically predicted k=0 energy (frequency) gap was verified. Equilibrium molecular-dynamics simulations were performed to emulate the experiment, assuming Yukawa-type interparticle interaction. The simulations and analytic calculations based both on lattice summation and on the quasilocalized charge approximation approach are in good agreement with the experimental findings and help in identifying and characterizing the observed phenomena.

Hartmann, P.; Donko, Z. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts 02467 (United States); Kalman, G. J. [Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts 02467 (United States); Kyrkos, S. [Department of Chemistry and Physics, Le Moyne College, 1419 Salt Springs Road, Syracuse, New York 13214 (United States); Golden, K. I. [Department of Mathematics and Statistics, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont 05401-1455 (United States); Rosenberg, M. [Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California, 92093 (United States)

2009-12-11T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

STABLE HIGH CONDUCTIVITY BILAYERED ELECTROLYTES FOR LOW TEMPERATURE SOLID OXIDE FUEL CELLS  

DOE Green Energy (OSTI)

Solid oxide fuel cells (SOFCs) are the future of energy production in America. They offer great promise as a clean and efficient process for directly converting chemical energy to electricity while providing significant environmental benefits (they produce negligible CO, HC, or NOx and, as a result of their high efficiency, produce about one-third less CO{sub 2} per kilowatt hour than internal combustion engines). Unfortunately, the current SOFC technology, based on a stabilized zirconia electrolyte, must operate in the region of 1000 C to avoid unacceptably high ohmic losses. These high temperatures demand (a) specialized (expensive) materials for the fuel cell interconnects and insulation, (b) time to heat up to the operating temperature and (c) energy input to arrive at the operating temperature. Therefore, if fuel cells could be designed to give a reasonable power output at lower temperatures tremendous benefits may be accrued, not the least of which is reduced cost. The problem is, at lower temperatures the conductivity of the conventional stabilized zirconia electrolyte decreases to the point where it cannot supply electrical current efficiently to an external load. The primary objectives of the proposed research is to develop a stable high conductivity (>0.05 S cm{sup -1} at 550 C) electrolyte for lower temperature SOFCs. This objective is specifically directed toward meeting the lowest (and most difficult) temperature criteria for the 21st Century Fuel Cell Program. Meeting this objective provides a potential for future transportation applications of SOFCs, where their ability to directly use hydrocarbon fuels could permit refueling within the existing transportation infrastructure. In order to meet this objective we are developing a functionally gradient bilayer electrolyte comprised of bismuth oxide on the air side and ceria on the fuel side. Bismuth oxide and doped ceria are among the highest ionic conducting electrolytes and in fact bismuth oxide based electrolytes are the only known solid oxide electrolytes to have an ionic conductivity that meets the program conductivity goal. We have previously demonstrated that this concept works, that a bismuth oxide/ceria bilayer electrolyte provides near theoretical open circuit potential (OCP) and is stable for 1400 h of fuel cell operation under both open circuit and maximum power conditions. More recently, we developed a computer model to determine the defect transport in this bilayer and have found that a bilayer comprised primarily of the more conductive component (bismuth oxide) is stable for 500 C operation. In this first year of the project we are obtaining necessary thermochemical data to complete the computer model as well as initial SOFC results based on thick 1-2 mm single and bilayer ceria/bismuth oxide electrolytes. We will use the computer model to obtain the optimum relative layer thickness as a function of temperature and air/fuel conditions. SOFCs will be fabricated with 1-2 mm single and bilayer electrolytes based on the modeling results, tested for OCP, conductivity, and stability and compared against the predictions. The computer modeling is a continuation of previous work under support from GRI and the student was available at the inception of the contract. However, the experimental effort was delayed until the beginning of the Spring Semester because the contract was started in October, 2 months after the start of our Fall Semester, and after all of the graduate students were committed to other projects. The results from both of these efforts are described in the following two sections: (1) Experimental; and (2) Computer Modeling.

Eric D. Wachsman

2000-10-01T23:59:59.000Z

22

Water permeation through stratum corneum lipid bilayers from atomistic simulations  

E-Print Network (OSTI)

Stratum corneum, the outermost layer of skin, consists of keratin filled rigid non-viable corneocyte cells surrounded by multilayers of lipids. The lipid layer is responsible for the barrier properties of the skin. We calculate the excess chemical potential and diffusivity of water as a function of depth in lipid bilayers with compositions representative of the stratum corneum using atomistic molecular dynamics simulations. The maximum in the excess free energy of water inside the lipid bilayers is found to be twice that of water in phospholipid bilayers at the same temperature. Permeability, which decreases exponentially with the free energy barrier, is reduced by several orders of magnitude as compared to with phospholipid bilayers. The average time it takes for a water molecule to cross the bilayer is calculated by solving the Smoluchowski equation in presence of the free energy barrier. For a bilayer composed of a 2:2:1 molar ratio of ceramide NS 24:0, cholesterol and free fatty acid 24:0 at 300K, we estimate the permeability P=3.7e-9 cm/s and the average crossing time \\tau_{av}=0.69 ms. The permeability is about 30 times smaller than existing experimental results on mammalian skin sections.

Chinmay Das; Peter D. Olmsted; Massimo G. Noro

2009-07-09T23:59:59.000Z

23

Properties of double-layered Ga-doped Al-zinc-oxide/titanium-doped indium-tin-oxide thin films prepared by dc magnetron sputtering applied for Si-based thin film solar cells  

Science Conference Proceedings (OSTI)

In this article, Ga-doped Al-zinc-oxide (GAZO)/titanium-doped indium-tin-oxide (ITIO) bi-layer films were deposited onto glass substrates by direct current (dc) magnetron sputtering. The bottom ITIO film, with a thickness of 200 nm, was sputtered onto the glass substrate. The ITIO film was post-annealed at 350 deg. C for 10-120 min as a seed layer. The effect of post-annealing conditions on the morphologies, electrical, and optical properties of ITIO films was investigated. A GAZO layer with a thickness of 1200 nm was continuously sputtered onto the ITIO bottom layer. The results show that the properties of the GAZO/ITIO films were strongly dependent on the post-annealed conditions. The spectral haze (T{sub diffuse}/T{sub total}) of the GAZO/ITIO bi-layer films increases upon increasing the post-annealing time. The haze and resistivity of the GAZO/ITIO bi-layer films were improved with the post-annealed process. After optimizing the deposition and annealing parameters, the GAZO/ITIO bi-layer film has an average transmittance of 83.20% at the 400-800 nm wavelengths, a maximum haze of 16%, and the lowest resistivity of 1.04 x 10{sup -3}{Omega} cm. Finally, the GAZO/ITIO bi-layer films, as a front electrode for silicon-based thin film solar cells, obtained a maximum efficiency of 7.10%. These encouraging experimental results have potential applications in GAZO/ITIO bi-layer film deposition by in-line sputtering without the wet-etching process and enable the production of highly efficient, low-cost thin film solar cells.

Wang, Chao-Chun; Wuu, Dong-Sing; Lin, Yang-Shih; Lien, Shui-Yang; Huang, Yung-Chuan; Liu, Chueh-Yang; Chen, Chia-Fu; Nautiyal, Asheesh; Lee, Shuo-Jen [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan (China); Department of Materials Science and Engineering, MingDao University, Changhua 52345, Taiwan (China); Department of Mechanical Engineering, Yuan Ze University, Taoyuan 320, Taiwan (China)

2011-11-15T23:59:59.000Z

24

Can a Carbon Nanotube Pierce through a Phospholipid Bilayer?  

E-Print Network (OSTI)

Great efficiency to penetrate into living cells is attributed to carbon nanotubes due to a number of direct and indirect observations of carbon nanotubes inside the cells. However, a direct evidence of physical translocation of nanotubes through phospholipid bilayers and the exact microscopic mechanism of their penetration into cells are still lacking. In order to test one of the inferred translocation mechanisms, namely the spontaneous piercing through the membrane induced only by thermal motion, we calculate the energy cost associated with the insertion of a carbon nanotube into a model phospholipid bilayer using the Single Chain Mean Field theory which is particularly suitable for the accurate measurements of equilibrium free energies. We find that the energy cost of the bilayer rupture is quite high compared to the energy of thermal motion. This conclusion may indirectly support other energy dependent translocation mechanisms such as, for example, endocytosis.

Sergey Pogodin; Vladimir A. Baulin

2010-10-07T23:59:59.000Z

25

AC/AB Stacking Boundaries in Bilayer Graphene  

Science Conference Proceedings (OSTI)

Boundaries, including phase boundaries, grain boundaries, and domain boundaries, are known to have an important influence on material properties. Here, dark-field (DF) transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) imaging are combined to provide a full view of boundaries between AB and AC stacking domains in bilayer graphene across length scales from discrete atoms to the macroscopic continuum. Combining the images with results obtained by density functional theory (DFT) and classical molecular dynamics calculations, we demonstrate that the AB/AC stacking boundaries in bilayer graphene are nanometer-wide strained channels, mostly in the form of ripples, producing smooth low-energy transitions between the two different stackings. Our results provide a new understanding of the novel stacking boundaries in bilayer graphene, which may be applied to other layered two-dimensional materials as well.

Lin, Junhao [ORNL; Fang, Wenjing [Massachusetts Institute of Technology (MIT); Zhou, Wu [ORNL; Lupini, Andrew R [ORNL; Idrobo Tapia, Juan C [ORNL; Kong, Jing [Massachusetts Institute of Technology (MIT); Pennycook, Stephen J [ORNL; Pantelides, Sokrates T [ORNL

2013-01-01T23:59:59.000Z

26

Graphene Monolayer Rotation on Ni(111) Facilities Bilayer Graphene Growth  

Science Conference Proceedings (OSTI)

Synthesis of bilayer graphene by chemical vapor deposition is of importance for graphene-based field effect devices. Here, we demonstrate that bilayer graphene preferentially grows by carbon-segregation under graphene sheets that are rotated relative to a Ni(111) substrate. Rotated graphene monolayer films can be synthesized at growth temperatures above 650 C on a Ni(111) thin-film. The segregated second graphene layer is in registry with the Ni(111) substrate and this suppresses further C-segregation, effectively self-limiting graphene formation to two layers.

Batzill M.; Sutter P.; Dahal, A.; Addou, R.

2012-06-11T23:59:59.000Z

27

Kinetics of the opening and closing of individual excitability-inducing material channels in a lipid bilayer  

E-Print Network (OSTI)

ABSTRACT The kinetics of the opening and closing of individual ion-conducting channels in lipid bilayers doped with small amounts of excitability-inducing material (EIM) are determined from discrete fluctuations in ionic current. The kinetics for the approach to steady-state conductance during voltage clamp are determined for lipid bilayers containing many EIM channels. The two sets of measurements are found to be consistent, verifying that the voltage-dependent conductance of the many-channel EIM system arises from the opening and closing of individual EIM channels. The opening and closing of the channels are Poisson processes. Transition rates for these processes vary exponentially with applied potential, implying that the energy difference between the open and closed states of an EIM channel is linearly proportional to the transmembrane electric field. A model incorporating the above properties of the EIM channels predicts the observed voltage dependence of ionic conductance and conductance relaxation time, which are also characteristic of natural electrically excitable membranes.

Gerald Ehrenstein; Robert Blumenthal; Ramon Latorre; Harold Lecar

1974-01-01T23:59:59.000Z

28

Topological insulating phases in mono and bilayer graphene  

E-Print Network (OSTI)

We analyze the influence of different quadratic interactions giving rise to time reversal invariant topological insulating phases in mono and bilayer graphene. We make use of the effective action formalism to determine the dependence of the Chern Simons coefficient on the different interactions.

Alberto Cortijo; Adolfo G. Grushin; Maria A. H. Vozmediano

2010-07-21T23:59:59.000Z

29

Evaporation-Induced Buckling and Fission of Microscale Droplet Interface Bilayers  

Science Conference Proceedings (OSTI)

Droplet interface bilayers (DIBs) are a robust platform for studying synthetic cellular membranes; however, to date no DIBs have been produced at cellular length scales. Here, we create microscale droplet interface bilayers ( DIBs) at the interface between aqueous femtoliter-volume droplets within an oil-filled microfluidic channel. The uniquely large area-to-volume ratio of the droplets results in strong evaporation effects, causing the system to transition through three distinct regimes. First, the two adjacent droplets shrink into the shape of a single spherical droplet, where an augmented lipid bilayer partitions two hemi-spherical volumes. In the second regime, the combined effects of the shrinking monolayers and growing bilayer force the confined bilayer to buckle to conserve its mass. Finally, at a bending moment corresponding to a critical shear stress, the buckling bilayer fissions a vesicle to regulate its shape and stress. The DIBs produced here enable evaporation-induced bilayer dynamics reminiscent of endo- and exocytosis in cells.

Boreyko, Jonathan B [ORNL; Mruetusatorn, Prachya [ORNL; Sarles, Stephen A [ORNL; Retterer, Scott T [ORNL; Collier, Pat [ORNL

2013-01-01T23:59:59.000Z

30

Final Technical Report: Grain Boundary Complexions and Transitions in Doped Silicon  

SciTech Connect

This four-year research project has advanced the fundamental knowledge of grain boundary (GB) complexions (i.e., "two-dimensional interfacial phases") and associated GB "phase" transitions in several grounds. First, a bilayer interfacial phase, which had been directly observed by microscopy only in complex ceramic systems in prior studies, has been identified in simpler systems such as Au-doped Si and Bi-doped Ni in this study, where the interpretations of the their formation mechanisms and microscopic images are less equivocal. Second, convincing evidence for the existence of a first-order GB transition from a nominally "clean" GB to a bilayer adsorption interfacial phase has been revealed for Au-doped Si; the confirmation of the first-order nature of interfacial transitions at GBs, which was rare in prior studies, is scientifically significant and technologically important. Third, the bilayer interfacial phase discovered in Bi-doped Ni has been found to be the cause of the mysterious liquid metal embrittlement phenomenon in this system; the exact atomic level mechanism of this phenomenon has puzzled the materials and physics communities for over a century. Finally, significant advancements have been made to establish phenomenological thermodynamic models for GB complexions and transitions. Since GB complexions can control the transport, mechanical and physical properties of a broad range of metallic and ceramic materials, the fundamental knowledge generated by this project can have broad impacts on materials design in general. In this regard, understanding and controlling GB phase behaviors (complexions and transitions) can be an important component for the "Materials Genome" project.

Jian Luo

2012-10-15T23:59:59.000Z

31

Seeded Growth of Single Crystal Bilayer Graphene Arrays  

Science Conference Proceedings (OSTI)

Atomic -Scale Characterization of Nb-Doped SrTiO?3 Nanostructures for .... Metal Oxide Nanofibers Produced by a ForceSpinning Method for Battery Electrodes.

32

Label-Free Sensing on Supported Lipid Bilayers  

E-Print Network (OSTI)

Cell membranes are integral for many biological processes. In addition to containing and protecting cellular contents and maintaining the chemical integrity of the cell, these interfaces host a variety of ligand-receptor interactions. These ligand-receptor interactions are important for cell signaling and transport and the ability to monitor them is key to understanding these processes. In addition, therapeutics and drug discovery is also aided by membrane-specific study, as the majority of drugs target receptors associated with the cell surface. The cell membrane can be effectively mimicked by the use of supported lipid bilayers, which provide a robust platform exhibiting the lateral fluidity and composition associated with cell membranes. The ability to study both ligand-receptor interactions as well as small molecule-membrane interactions on these model membranes is aided by the fact that these assays can be multiplexed and are amenable to use with low sample volumes with high throughput. Our laboratory has recently developed a strategy for fluorescent microscopy studies of ligand-receptor interactions on supported lipid bilayers without the use of fluorescently-labeled analytes. This technique involves the incorporation of pH-sensitive fluorophores into the composition of the supported lipid bilayer as embedded reporter dyes. It was determined that this assay can operate as either a “turn-on” or a “turn-off” sensor depending on the analyte to be detected. It was additionally found that modulating the ionic strength of the operating buffer allows for tuning the operating pH and sensitivity of the assay. This label-free technique can be utilized to monitor small peptide interactions with bilayers containing specific phospholipids. Basic amino acid sequences which are associated with transporting contents across membranes or anti-microbial activity can be monitored binding to negatively charged bilayers without the use of labels. Not only is this a sensitive technique for detecting small peptides, but thermodynamic data can be extracted as well. In a final set of experiments, the interaction of proteins with phosphatidylserine (PS) in supported lipid bilayers is observed by utilizing PS-Cu2+-induced quenching of fluorophores. Disruption of this metal-phospholipid, specifically by Ca2+-dependent protein kinases, results in a turn-on fluorescent assay, which can be used to monitor the binding of the protein to PS and the effects of other metal interference.

Robison, Aaron 1982-

2012-12-01T23:59:59.000Z

33

Bilayer Thickness Mismatch Controls Domain Size in Model Membranes  

Science Conference Proceedings (OSTI)

The observation of lateral phase separation in lipid bilayers has received considerable attention, especially in connection to lipid raft phenomena in cells. It is widely accepted that rafts play a central role in cellular processes, notably signal transduction. While micrometer-sized domains are observed with some model membrane mixtures, rafts much smaller than 100 nm beyond the reach of optical microscopy are now thought to exist, both in vitro and in vivo. We have used small-angle neutron scattering, a probe free technique, to measure the size of nanoscopic membrane domains in unilamellar vesicles with unprecedented accuracy. These experiments were performed using a four-component model system containing fixed proportions of cholesterol and the saturated phospholipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), mixed with varying amounts of the unsaturated phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dioleoylsn- glycero-3-phosphocholine (DOPC). We find that liquid domain size increases with the extent of acyl chain unsaturation (DOPC:POPC ratio). Furthermore, we find a direct correlation between domain size and the mismatch in bilayer thickness of the coexisting liquid-ordered and liquid-disordered phases, suggesting a dominant role for line tension in controlling domain size. While this result is expected from line tension theories, we provide the first experimental verification in free-floating bilayers. Importantly, we also find that changes in bilayer thickness, which accompany changes in the degree of lipid chain unsaturation, are entirely confined to the disordered phase. Together, these results suggest how the size of functional domains in homeothermic cells may be regulated through changes in lipid composition.

Heberle, Frederick A [ORNL; Petruzielo, Robin S [ORNL; Pan, Jianjun [ORNL; Drazba, Paul [ORNL; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Feigenson, Gerald [Cornell University; Katsaras, John [ORNL

2013-01-01T23:59:59.000Z

34

Effect of an electric field on a floating lipid bilayer: a neutron reflectivity study  

E-Print Network (OSTI)

We present here a neutron reflectivity study of the influence of an alternative electric field on a supported phospholipid double bilayer. We report for the first time a reproducible increase of the fluctuation amplitude leading to the complete unbinding of the floating bilayer. Results are in good agreement with a semi-quantitative interpretation in terms of negative electrostatic surface tension.

Sigolène Lecuyer; Giovanna Fragneto; Thierry Charitat

2006-11-06T23:59:59.000Z

35

Synthesis of high-quality monolayer and bilayer graphene on copper using chemical vapor deposition  

E-Print Network (OSTI)

/IG of the Raman spectra (red line in Fig. 6a) taken from the graphene grown on high purity Cu (99.999%) is above 3Synthesis of high-quality monolayer and bilayer graphene on copper using chemical vapor deposition determining the growth of high-quality monolayer and bilayer graphene on Cu using chemical vapor deposition

36

Dual Gate Thin Film Transistors Based on Indium Oxide Active Layers  

SciTech Connect

Polycrystalline Indium Oxide (In{sub 2}O{sub 3}) thin films were employed as an active channel layer for the fabrication of bottom and top gate thin film transistors. While conventional SiO{sub 2} served as a bottom gate dielectric, cross-linked poly-4-vinylphenol (PVP) was used a top gate dielectric. These nano-crystalline TFTs exhibited n-channel behavior with their transport behavior highly dependent on the thickness of the channel. The correlation between the thickness of the active layer and TFT parameters such as on/off ratio, field-effect mobility, threshold voltage were carried out. The optical spectra revealed a high transmittance in the entire visible region, thus making them promising candidates for the display technology.

Kekuda, Dhananjaya; Rao, K. Mohan; Tolpadi, Amita [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal 576 104 (India); Chu, C. W. [Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan (China)

2011-07-15T23:59:59.000Z

37

Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces  

Science Conference Proceedings (OSTI)

Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.

Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L

2008-10-30T23:59:59.000Z

38

Bilayer superfluidity of fermionic polar molecules: Many-body effects  

Science Conference Proceedings (OSTI)

We study the BCS superfluid transition in a single-component fermionic gas of dipolar particles loaded in a tight bilayer trap, with the electric dipole moments polarized perpendicular to the layers. Based on the detailed analysis of the interlayer scattering, we calculate the critical temperature of the interlayer superfluid pairing transition when the layer separation is both smaller (dilute regime) and on the order or larger (dense regime) than the mean interparticle separation in each layer. Our calculations go beyond the standard BCS approach and include the many-body contributions resulting in the mass renormalization, as well as additional contributions to the pairing interaction. We find that the many-body effects have a pronounced effect on the critical temperature and can either decrease (in the very dilute limit) or increase (in the dense and moderately dilute limits) the transition temperature as compared to the BCS approach.

Baranov, M. A. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck (Austria); RRC 'Kurchatov Institute', Kurchatov Square 1, 123182 Moscow (Russian Federation); Micheli, A.; Ronen, S.; Zoller, P. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck (Austria)

2011-04-15T23:59:59.000Z

39

Doped zinc oxide microspheres  

DOE Patents (OSTI)

A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

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

1993-12-14T23:59:59.000Z

40

pH-sensitive resist materials for combined photolithographic patterning of proteins and fluid lipid bilayers  

E-Print Network (OSTI)

Photolithography of a pH-sensitive photoresist polymer was performed to pattern both lipid bilayers and proteins onto the same surface. The motivation behind this was to create a substrate mimicking an array of antigen- ...

Shah, Mirat

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

STABLE HIGH CONDUCTIVITY BILAYERED ELECTROLYTES FOR LOW TEMPERATURE SOLID OXIDE FUEL CELLS  

DOE Green Energy (OSTI)

Solid oxide fuel cells (SOFCs) are the future of energy production in America. They offer great promise as a clean and efficient process for directly converting chemical energy to electricity while providing significant environmental benefits (they produce negligible hydrocarbons, CO, or NO{sub x} and, as a result of their high efficiency, produce about one-third less CO{sub 2} per kilowatt hour than internal combustion engines). Unfortunately, the current SOFC technology, based on a stabilized zirconia electrolyte, must operate in the region of 1000 C to avoid unacceptably high ohmic losses. These high temperatures demand (a) specialized (expensive) materials for the fuel cell interconnects and insulation, (b) time to heat up to the operating temperature and (c) energy input to arrive at the operating temperature. Therefore, if fuel cells could be designed to give a reasonable power output at low to intermediate1 temperatures tremendous benefits may be accrued. At low temperatures, in particular, it becomes feasible to use ferritic steel for interconnects instead of expensive and brittle ceramic materials such as those based on LaCrO{sub 3}. In addition, sealing the fuel cell becomes easier and more reliable; rapid start-up is facilitated; thermal stresses (e.g., those caused by thermal expansion mismatches) are reduced; radiative losses ({approx}T{sup 4}) become minimal; electrode sintering becomes negligible and (due to a smaller thermodynamic penalty) the SOFC operating cycle (heating from ambient) would be more efficient. Combined, all these improvements further result in reduced initial and operating costs. The problem is, at lower temperatures the conductivity of the conventional stabilized zirconia electrolyte decreases to the point where it cannot supply electrical current efficiently to an external load. The primary objectives of the proposed research are to develop a stable high conductivity (> 0.05 S cm{sup -1} at {le} 550 C) electrolyte for lower temperature SOFCs. This objective is specifically directed toward meeting the lowest (and most difficult) temperature criteria for the 21st Century Fuel Cell Program. Meeting this objective provides a potential for future transportation applications of SOFCs, where their ability to directly use hydrocarbon fuels could permit refueling within the existing transportation infrastructure. In order to meet this objective we are developing a functionally gradient bilayer electrolyte comprised of bismuth oxide on the air side and ceria on the fuel side. Bismuth oxide and doped ceria are among the highest ionic conducting electrolytes and in fact bismuth oxide based electrolytes are the only known solid oxide electrolytes to have an ionic conductivity that meets the program conductivity goal.

Eric D. Wachsman; Keith L. Duncan

2001-09-30T23:59:59.000Z

42

Electron-doping  

NLE Websites -- All DOE Office Websites (Extended Search)

Electron-doping Electron-doping evolution of the low-energy spin excitations in the iron arsenide superconductor BaFe 2-x Ni x As 2 Miaoyin Wang, 1 Huiqian Luo, 2 Jun Zhao, 1 Chenglin Zhang, 1 Meng Wang, 2,1 Karol Marty, 3 Songxue Chi, 4 Jeffrey W. Lynn, 4 Astrid Schneidewind, 5,6 Shiliang Li, 2, * and Pengcheng Dai 1,2,3,† 1 Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA 2 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China 3 Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA 4 NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA 5 Gemeinsame Forschergruppe HZB, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109

43

Bilayer self-assembly on a hydrophilic, deterministically nano-patterned surface  

Science Conference Proceedings (OSTI)

We present measurements of the in-situ, microscopic architecture of a self-assembled bilayer at the interface between a regularly nano-patterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nano-scaled holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this study, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion (VF) or by the Langmuir Schaefer (L-S) technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nano-patterned features.

Smith, Gregory Scott [ORNL] [ORNL; Jung, Seung-Yong [ORNL] [ORNL; Browning, Jim [ORNL] [ORNL; Keum, Jong Kahk [ORNL] [ORNL; Lavrik, Nickolay V [ORNL] [ORNL; Alemseghed, Mussie G [ORNL] [ORNL; Collier, Pat [ORNL] [ORNL

2013-01-01T23:59:59.000Z

44

Bilayer Polymer Solar Cells with Improved Power Conversion Efficiency and Enhanced Spectrum Coverage  

SciTech Connect

We demonstrate the construction of an efficient bilayer polymer solar cell comprising of Poly(3-hexylthiophene)(P3HT) as a p-type semiconductor and asymmetric fullerene (C{sub 70}) as n-type counterparts. The bilayer configuration was very efficient compared to the individual layer performance and it behaved like a regular p-n junction device. The photovoltaic characteristic of the bilayers were studied under AM 1.5 solar radiation and the optimized device parameters are the following: Voc = 0.5V, Jsc = 10.1 mA/cm{sup 2}, FF = 0.60 and power conversion efficiency of 3.6 %. A high fill factor of {approx}0.6 was achieved, which is only slightly reduced at very intense illumination. Balanced mobility between p-and n-layers is achieved which is essential for achieving high device performance. Correlation between the crystallinity, morphology and the transport properties of the active layers is established. The External quantum efficiency (EQE) spectral distribution of the bilayer devices with different processing solvents correlates well with the trends of short circuit current densities (J{sub sc}) measured under illumination. Efficiency of the bilayer devices with rough P3HT layer was found to be about 3 times higher than those with a planar P3HT surface. Hence it is desirable to have a larger grains with a rough surface of P3HT layer for providing larger interfacial area for the exciton dissociation.

Kekuda, Dhananjaya [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal, India 576 104 (India); Chu, Chih-Wei [Research Center for Applied Science, Academia Sinica, Taipei, Taiwan 300 13 (China)

2011-10-20T23:59:59.000Z

45

Doping of gallium nitride using disilane  

Science Conference Proceedings (OSTI)

Keywords: disilane, gallium nitride, metalorganic chemical vapor deposition, organometallic vapor phase epitaxy, silicon doping

A. E. Wickenden; L. B. Rowland; K. Doverspike; D. K. Gaskill; J. A. Freitas, Jr.; D. S. Simons; P. H. Chi

1995-11-01T23:59:59.000Z

46

Superhard behaviour, low residual stress, and unique structure in diamond-like carbon films by simple bilayer approach  

Science Conference Proceedings (OSTI)

Simple bilayer approach is proposed for synthesizing hard and superhard diamond-like carbon (DLC) coatings with reduced residual stress. For this, M/DLC bilayer (M = Ti and Cu) structures are grown using hybrid system involving radio frequency (RF)-sputtering and RF-plasma enhanced chemical vapor deposition techniques. Ti/DLC bilayer deposited at negative self bias of 100 V shows superhard behaviour with hardness (H) as 49 GPa. Cu/DLC bilayer grown at self bias of 100 V exhibits hard behaviour with H as 22.8 GPa. The hardness of Ti/DLC (Cu/DLC) bilayer gets changed from superhard (hard) to hard (moderate hard) regime, when the self bias is raised to 300 V. Residual stress in Ti/DLC (Cu/DLC) bilayer is found to be significantly low that varies in the range of 1 GPa-1.65 GPa (0.8 GPa-1.6 GPa). The microstructure and morphology are studied by Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). SEM and AFM pictures reveal the creation of nanostructured features in the deposited bilayers. Raman, SEM, and AFM analyses are correlated with the nano-mechanical properties. Owing to excellent nano-mechanical properties, these bilayers can find their direct industrial applications as hard and protective coatings.

Dwivedi, Neeraj [Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), KS Krishnan Road, New Delhi 110 012 (India); Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India); Kumar, Sushil [Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), KS Krishnan Road, New Delhi 110 012 (India); Malik, Hitendra K. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)

2012-07-15T23:59:59.000Z

47

Dynamics of lipid bilayers from comparative analysis of 2 nuclear magnetic resonance relaxation data as a function  

E-Print Network (OSTI)

to the predominant mechanisms of nuclear spin relax- ation in lipid bilayers. To critically test various dDynamics of lipid bilayers from comparative analysis of 2 H and 13 C nuclear magnetic resonance September 1997 Analysis of the nuclear spin relaxation rates of lipid membranes provides a powerful means

Brown, Michael F.

48

Determination of the electronic structure of bilayer graphene from infrared spectroscopy results  

Science Conference Proceedings (OSTI)

We present an experimental study of the infrared conductivity, transmission, and reflection of a gated bilayer graphene and their theoretical analysis within the Slonczewski-Weiss-McClure (SWMc) model. The infrared response is shown to be governed by the interplay of the interband and the intraband transitions among the four bands of the bilayer. The position of the main conductivity peak at thecharge-neutrality point is determined by the interlayer tunneling frequency. The shift of this peak as a function of the gate voltage gives information about less known parameters of the SWMc model such as those responsible for the electron-hole and sublattice asymmetries. These parameter values are shown to be consistent with recent electronic structure calculations for the bilayer graphene and the SWMc parameters commonly used for the bulk graphite.

Zhang, L. M.; Li, Z. Q.; Basov, D. N.; Fogler, M. M.; Hao, Z.; Martin, Michael C.

2008-11-12T23:59:59.000Z

49

Nanocrystal doped matrixes  

DOE Patents (OSTI)

Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

Parce, J. Wallace (Palo Alto, CA); Bernatis, Paul (Sunnyvale, CA); Dubrow, Robert (San Carlos, CA); Freeman, William P. (San Mateo, CA); Gamoras, Joel (Vallejo, CA); Kan, Shihai (San Jose, CA); Meisel, Andreas (Redwood City, CA); Qian, Baixin (Sunnyvale, CA); Whiteford, Jeffery A. (Belmont, CA); Ziebarth, Jonathan (Palo Alto, CA)

2010-01-12T23:59:59.000Z

50

Temperature dependence of the diffusive conductivity of bilayer graphene Shaffique Adam and M. D. Stiles  

E-Print Network (OSTI)

for linear dispersion upper curve and parabolic dis- persion lower curve graphene. Dashed lines show the high to be linear in gate voltage so it is unclear what the dominant scattering mechanism in bi- layer graphene. Color online Bilayer graphene mobility as a function of backgate voltage Vg, normalized by the mobility

Adam, Shaffique

51

Atomic Force Microscopy Studies of Lipophosphoglycan (LPG) Molecules in Lipid Bilayers  

SciTech Connect

Lipophosphoglycan (LPG) is a lypopolysaccharide found on the surface of the parasite Leishmania donovani that is thought to play an essential role in the infection of humans with leishamniasis. LPG acts as an adhesion point for the parasite to the gut of the sand fly, whose bite is responsible for transmitting the disease. In addition, LPG acts to inhibit protein kinase C (PKC) in the human macrophage, possibly by structural changes in the membrane. The Ca{sup 2+} ion is believed to play a role in the infection cycle, acting both as a crosslinker between LPG molecules and by playing a part in modulating PKC activity. To gain insight into the structure of LPG within a supported lipid membrane and into the structural changes that occur due to Ca{sup 2+} ions, we have employed the atomic force microscope (AFM). We have observed that the LPG molecules inhibit bilayer fusion, resulting in bilayer islands on the mica surface. One experiment suggests that the LPG molecules are parallel to the mica surface and that the structure of the LPG changes upon addition of Ca{sup 2+}, with an increase in the height of the LPG molecules from the bilayer surface and an almost complete coverage of LPG on the bilayer island.

LAST, JULIE A.; HUBER, TINA; SASAKI, DARRYL Y.; SALVATORE, BRIAN; TURCO, SALVATORE J.

2003-03-01T23:59:59.000Z

52

Electrical tuning of valley magnetic moment through symmetry control in bilayer MoS2  

SciTech Connect

Crystal symmetry governs the nature of electronic Bloch states. For example, in the presence of time-reversal symmetry, the orbital magnetic moment and Berry curvature of the Bloch states must vanish unless inversion symmetry is broken1. In certain two-dimensional electron systems such as bilayer graphene, the intrinsic inversion symmetry can be broken simply by applying a perpendicular electric field2,3. In principle, this offers the possibility of switching on/off and continuously tuning the magnetic moment and Berry curvature near the Dirac valleys by reversible electrical control4,5. Here we investigate this possibility using polarization-resolved photoluminescence of bilayer MoS2, which has the same symmetry as bilayer graphene but has a bandgap in the visible spectrum6,7 allowing direct optical probing5,8 12. We find that in bilayer MoS2 the circularly polarized photoluminescence can be continuously tuned from 15% to 15% as a function of gate voltage, whereas in structurally non-centrosymmetric monolayer MoS2 the photoluminescence polarization is gate independent. The observations are well explained as resulting from the continuous variation of orbital magnetic moments between positive and negative values through symmetry control.

Wu, Sanfeng [University of Washington, Seattle; Ross, Jason [University of Washington, Seattle; Liu, G. B. [University of Hong Kong, The; Aivazian, Grant [University of Washington, Seattle; Jones, Aaron [University of Washington, Seattle; Fei, Zaiyao [University of Washington, Dept Phys, Seattle, WA; Zhu, Wenguang [University of Tennessee, Knoxville (UTK); Xiao, Di [ORNL; Yao, Wang [University of Hong Kong, The; Cobden, David [University of Washington, Dept Phys, Seattle, WA; Xu, Xiaodong [University of Washington

2013-01-01T23:59:59.000Z

53

Raman spectra of out-of-plane phonons in bilayer graphene  

E-Print Network (OSTI)

The double resonance Raman spectra of the overtone of the out-of-plane tangential optical (oTO) phonon and of combinations of the LO, ZO, and ZA phonons with one another are calculated for bilayer graphene. In the case of ...

Sato, Kentaro

54

Spatial Mapping of the Dirac Point in Monolayer and Bilayer Graphene  

Science Conference Proceedings (OSTI)

We have mapped the Dirac point in exfoliated monolayer and bilayer graphene using spatially resolved scanning tunneling spectroscopy measurements at low temperature. The Dirac-point shifts in energy at different locations in graphene. However, a cross ... Keywords: Dirac point, graphene, scanning tunneling microscope (STM), spectroscopy

A. Deshpande; Wenzhong Bao; Zeng Zhao; Chun Ning Lau; B. LeRoy

2011-01-01T23:59:59.000Z

55

Combustion Synthesis of Doped Calcium Cobaltate Thermoelectric ...  

Science Conference Proceedings (OSTI)

Symposium, Innovative Processing and Synthesis of Ceramics, Glasses and Composites. Presentation Title, Combustion Synthesis of Doped Calcium Cobaltate ...

56

Microstructural Characteristics of Nano Calcium Phosphates Doped ...  

Science Conference Proceedings (OSTI)

Presentation Title, Microstructural Characteristics of Nano Calcium Phosphates Doped with Fluoride and Titanium Ions. Author(s), Serap Gungor Geridonmez, ...

57

Boron doping a semiconductor particle  

DOE Patents (OSTI)

A method (10,30) of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried (16), with the boron film then being driven (18) into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out (38) into piles and melted/fused (40) with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements.

Stevens, Gary Don (18912 Ravenglen Ct., Dallas, TX 75287); Reynolds, Jeffrey Scott (703 Horizon, Murphy, TX 75094); Brown, Louanne Kay (2530 Poplar Tr., Garland, TX 75042)

1998-06-09T23:59:59.000Z

58

Potential commercial application of a bi-layer bone-ligament regeneration scaffold to anterior cruciate ligament replacement  

E-Print Network (OSTI)

A business model was created in order to explore the commercial application of a bi-layer bone-ligament scaffold to the treatment of torn anterior cruciate ligaments (ACL) requiring replacement. The two main keys in producing ...

Li, Jessica C. (Jessica Ching-Yi)

2006-01-01T23:59:59.000Z

59

Method of doping a semiconductor  

DOE Patents (OSTI)

A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

Yang, Chiang Y. (Miller Place, NY); Rapp, Robert A. (Columbus, OH)

1983-01-01T23:59:59.000Z

60

Under the influence of alcohol: The effect of ethanol and methanol on lipid bilayers  

E-Print Network (OSTI)

Extensive microscopic molecular dynamics simulations have been performed to study the effects of short-chain alcohols, methanol and ethanol, on two different fully hydrated lipid bilayer systems in the fluid phase at 323 K. It is found that ethanol has a stronger effect on the structural properties of the membranes. In particular, the bilayers become more fluid and permeable: Ethanol molecules are able to penetrate through the membrane in typical time scales of about 200 ns whereas for methanol that time scale is considerably longer, at least of the order of microseconds. We find good agreement with NMR and micropipette studies. We have also measured partitioning coefficients and the rate of crossing events for alcohols, i.e., typical time scale it takes for a molecule to cross the lipid bilayer and to move from one leaflet to the other. For structural properties, two-dimensional centre of mass radial-distribution functions indicate the possibility for quasi long-range order for ethanol-ethanol correlations in contrast to liquid-like behaviour for all other combinations.

Michael Patra; Emppu Salonen; Emma Terama; Roland Faller; Bryan W. Lee; Juha Holopainen; Mikko Karttunen

2004-08-05T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Micro/nano-patterning of supported lipid bilayers: biophysical studies and membrane-associated species separation  

E-Print Network (OSTI)

Micro/nano-patterning of supported lipid bilayers (SLBs) has shown considerable potential for addressing fundamental biophysical questions about cell membrane behavior and the creation of a new generation of biosensors. Herein are presented several novel lithographic methods for the size-controlled patterning of SLBs from the microscale to the nanoscale. Using these methods, chemically distinct types of phospholipid bilayers and/or Escherichia Coli (E. Coli) membranes can be spatially addressed on a single microchip. These arrays can, in turn, be employed in the studies of multivalent ligand-receptor interactions, enzyme kinetics, SLBs size limitation, and membrane-associated species separation. The investigations performed in the Laboratory for Biological Surface Science include the following projects. Chapters II and III describe the creation of lab-on-a-chip based platforms by patterning SLBs in microfluidic devices, which were employed in high throughput binding assays for multivalent ligand-receptor interactions between cholera toxin B subunits (CTB) and ganglioside GM1. The studies on the effect of ligand density for multivalent CTB-GM1 interactions revealed that the CTB-GM1 binding weakened with increasing GM1 density. Such a result can be explained by the clustering of GM1 on the supported phospholipid membranes, which in turn inhibits the binding of CTB. Chapter IV characterizes the enzymatic activity of phosphatase tethered to SLBs in a microfluidic device. Higher turnover rate and catalytic efficiency were observed at low enzyme surface densities, ascribing to the low steric crowding hindrance and high enzyme fluidity, as well as the resulting improvement of substrate accessibility and affinity of enzyme catalytic sites. Chapter V presents sub-100 nm patterning of supported biomembranes by atomic force microscopy (AFM) based nanoshaving lithography. Stable SLBs formed by this method have a lower size limit of ~ 55 nm in width. This size limit stems from a balance between a favorable bilayer adhesion energy and an unfavorable bilayer edge energy. Finally, chapter VI demonstrates the electrophoretic separation of membrane-associated fluorophores in polymer-cushioned lipid bilayers. This electrophoretic method was applied to the separation of membrane proteins in E. Coli ghost membranes.

Shi, Jinjun

2008-05-01T23:59:59.000Z

62

Phosphorus doping a semiconductor particle  

DOE Patents (OSTI)

A method of phosphorus doping a semiconductor particle using ammonium phosphate is disclosed. A p-doped silicon sphere is mixed with a diluted solution of ammonium phosphate having a predetermined concentration. These spheres are dried with the phosphorus then being diffused into the sphere to create either a shallow or deep p-n junction. A good PSG glass layer is formed on the surface of the sphere during the diffusion process. A subsequent segregation anneal process is utilized to strip metal impurities from near the p-n junction into the glass layer. A subsequent HF strip procedure is then utilized to removed the PSG layer. Ammonium phosphate is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirement. 1 fig.

Stevens, G.D.; Reynolds, J.S.

1999-07-20T23:59:59.000Z

63

Lanthanide doped barium phosphorous oxide scintillators  

DOE Patents (OSTI)

The present invention provides for a composition comprising an inorganic scintillator comprising a lanthanide-doped barium phosphorous oxide useful for detecting nuclear material.

Borade, Ramesh B; Bourret-Courchesne, Edith; Denzo, Stephen E

2013-02-26T23:59:59.000Z

64

Lanthanide doped strontium barium mixed halide scintillators  

DOE Patents (OSTI)

The present invention provides for a composition comprising an inorganic scintillator comprising a lanthanide-doped strontium barium mixed halide useful for detecting nuclear material.

Gundiah, Gautam; Bizarri, Gregory; Hanrahan, Stephen M; Bourret-Courchesne, Edith; Derenzo, Stephen E

2013-07-16T23:59:59.000Z

65

Co-doped La - Programmaster.org  

Science Conference Proceedings (OSTI)

Author(s), Sapna Gupta, Manoj K Mahapatra, Prabhakar Singh. On-Site Speaker (Planned), Sapna Gupta. Abstract Scope, Nickel and titanium co-doped mixed ...

66

Effect of radical fluorination on mono- and bi-layer graphene in Ar/F{sub 2} plasma  

SciTech Connect

Fluorinated graphene has the possibility to achieve unique properties and functions in graphene. We propose a highly controlled fluorination method utilizing fluorine radicals in Ar/F{sub 2} plasma. To suppress ion bombardments and improve the reaction with fluorine radicals on graphene, the substrate was placed 'face down' in the plasma chamber. Although monolayer graphene was more reactive than bilayer, fluorination of bilayer reached the level of I{sub D}/I{sub G} {approx} 0.5 in Raman D peak intensity at 532 nm excitation. Annealing fluorinated samples proved reversibility of radical fluorination for both mono- and bi-layer graphenes. X-ray photoelectron spectroscopy showed the existence of carbon-fluorine bonding.

Tahara, K.; Iwasaki, T.; Hatano, M. [Department of Physical Electronics, Tokyo Institute of Technology, Tokyo 152-8552 (Japan); Matsutani, A. [Semiconductor and MEMS Processing Center, Technical Department, Tokyo Institute of Technology, Tokyo 226-8503 (Japan)

2012-10-15T23:59:59.000Z

67

Neutron transmutation doping of polycrystalline silicon  

DOE Green Energy (OSTI)

Chemical vapor deposition (CVD) of doped silane has been used by others to deposit a polycrytalline silicon film (polysil) on metal or graphite substrates, but dopant migration to grain boundaries during deposition apparently prohibits attaining a uniform or desired dopant concentration. In contrast, we have used neutron transmutation doping to introduce a uniform phosphorus dopant concentration in commercially available undoped CVD polysil at doping concentrations greater than or equal to 2 x 10/sup 15/ cm/sup -3/. Radiation damage annealing to 800/sup 0/C did not indicate dopant migration. Carrier mobility increased with doping concentration and the minority carrier lifetime (MCL) appears to be comparable to that of neutron transmutation doped (NTD) single crystal Si. Application of this technique to photovoltaic solar cell fabrication is discussed.

Cleland, J.W.; Westbrook, R.D.; Wood, R.F.; Young, R.T.

1976-04-01T23:59:59.000Z

68

A Novel Phase of Compressed Bilayers That Models the Prestalk Transition  

Science Conference Proceedings (OSTI)

The force model of protein-mediated membrane fusion hypothesizes that fusion is driven by mechanical forces exerted on the membranes, but many details are unknown. Here, we investigated by x-ray diffraction the consequence of applying compressive force on a stack of membranes against the hydration barrier. We found that as the osmotic pressure increased, the lamellar phase transformed first to a new phase of tetragonal lattice (T-phase) over a narrow range of relative humidity, and then to a phase of rhombohedral lattice. The unit cell structure changed from parallel bilayers to a bent configuration with a point contact between adjacent bilayers and then to the stalk hemifusion configuration. The T-phase is discussed as a possible transition state in the membrane merging pathway of fusion. We estimate the work required to form the T-phase and the subsequent hemifusion-stalk-resembling R-phase. The work for the formation of a stalk is compatible with the energy estimated to be released by several SNARE complexes.

Qian, Shuo [ORNL

2012-01-01T23:59:59.000Z

69

Bilayer Structure and Lipid Dynamics in a Model Stratum Corneum with Oleic Acid  

DOE Green Energy (OSTI)

The stratum corneum is the uppermost layer of the skin and acts as a barrier to keep out contaminants and retain moisture. Understanding the molecular structure and behavior of this layer will provide guidance for optimizing its biological function. In this study we use a model mixture comprised of equimolar portions of ceramide NS (24:0), lignoceric acid, and cholesterol to model the effect of the addition of small amounts of oleic acid to the bilayer at 300 and 340 K. Five systems at each temperature have been simulated with concentrations between 0 and 0.1 mol % oleic acid. Our major finding is that subdiffusive behavior over the 200 ns time scale is evident in systems at 340 K, with cholesterol diffusion being enhanced with increased oleic acid. Importantly, cholesterol and other species diffuse faster when radial densities indicate nearest neighbors include more cholesterol. We also find that, with the addition of oleic acid, the bilayer midplane and interfacial densities are reduced and there is a 3% decrease in total thickness occurring mostly near the hydrophilic interface at 300 K with reduced overall density at 340 K. Increased interdigitation occurs independent of oleic acid with a temperature increase. Slight ordering of the long non-hydroxy fatty acid of the ceramide occurs near the hydrophilic interface as a function of the oleic acid concentration, but no significant impact on hydrogen bonding is seen in the chosen oleic acid concentrations.

Hoopes, Matthew I.; Noro, Massimo G.; Longo, Marjorie L.; Faller, Roland

2011-03-31T23:59:59.000Z

70

PEN/Si3N4 bilayer film for dc bus capacitors in power converters in hybrid electric vehicles  

Science Conference Proceedings (OSTI)

High performance hybrid bilayer capacitorfilm has been developed by controlled deposition of silicon nitride (Si3N4) on polyethylene naphthalate (PEN). It was found that silicon nitride prepared with plasma-enhanced chemical vapor deposition can significantly increase the dielectric constant (K) and energy density of PEN by more than 20% and 50%

Chen Zou; Qiming Zhang; Shihai Zhang; Douglas Kushner; Xin Zhou; Richard Bernard; Raymond J. Orchard Jr.

2011-01-01T23:59:59.000Z

71

Bond Orientational Order Parameters in the Crystalline Phases of the Classical Yukawa-Wigner Bilayers  

E-Print Network (OSTI)

We present a study of the structural properties of the crystalline phases for a planar bilayer of particles interacting via repulsive Yukawa potentials in the weak screening region. The study is done with Monte Carlo computations and the long ranged contributions to energy are taken into account with the Ewald method for quasi-two dimensional systems. Two first order phase transitions (fluid-solid and solid-solid) and one second order transition (solid-solid) are found when the surface density is varied at constant temperature. A particular attention is pay to the characteristics of the crystalline phases by the analysis of bond orientational order parameters and center-to-center correlations functions.

Martial Mazars

2008-10-24T23:59:59.000Z

72

Domain Growth, Budding, and Fission in Phase Separating Self-Assembled Fluid Bilayers  

E-Print Network (OSTI)

A systematic investigation of the phase separation dynamics in self-assembled multi-component bilayer fluid vesicles and open membranes is presented. We use large-scale dissipative particle dynamics to explicitly account for solvent, thereby allowing for numerical investigation of the effects of hydrodynamics and area-to-volume constraints. In the case of asymmetric lipid composition, we observed regimes corresponding to coalescence of flat patches, budding, vesiculation and coalescence of caps. The area-to-volume constraint and hydrodynamics have a strong influence on these regimes and the crossovers between them. In the case of symmetric mixtures, irrespective of the area-to-volume ratio, we observed a growth regime with an exponent of 1/2. The same exponent is also found in the case of open membranes with symmetric composition.

Mohamed Laradji; P. B. Sunil Kumar

2006-02-02T23:59:59.000Z

73

Raman spectra of bilayer graphene covered with Poly(methyl methacrylate) thin film  

SciTech Connect

The Raman spectra of bilayer graphene covered with poly(methyl methacrylate) (PMMA) were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely caused by graphene compression induced by the circular bubble of the thin PMMA film generated by laser irradiation. Our findings may contribute to the application of PMMA in the strain engineering of graphene nanodevices.

Xia Minggang [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, 710049 (China); Center on Experimental Physics, School of Science, Xi'an Jiaotong University, 710049 (China); Su Zhidan; Zhang Shengli [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, 710049 (China); Department of Applied Physics, School of Science, Xi'an Jiaotong University, 710049 (China)

2012-09-15T23:59:59.000Z

74

Bilayer membranes in micro-fluidics: from gel emulsions to soft functional devices  

E-Print Network (OSTI)

We outline a concept of self-assembled soft matter devices based on micro-fluidics, which use surfactant bilayer membranes as their main building blocks, arrested in geometric structures provided by top-down lithography. Membranes form spontaneously when suitable water-in-oil emulsions are forced into micro-fluidic channels at high dispersed-phase volume fractions. They turn out to be remarkably stable even when pumped through the micro-fluidic channel system. Their geometric arrangement is self-assembling, driven by interfacial energy and wetting forces. The ordered membrane arrays thus emerging can be loaded with amphiphilic functional molecules, ion channels, or just be used as they are, exploiting their peculiar physical properties. For wet electronic circuitry, the aqueous droplets then serve as the 'solder points'. Furthermore, the membranes can serve as well-controlled coupling media between chemical processes taking place in adjacent droplets. This is shown for the well-known Belousov-Zhabotinski reac...

Thutupalli, Shashi; Seemann, Ralf; 10.1039/C0SM00312C

2010-01-01T23:59:59.000Z

75

Materials - Transient doping success | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Materials - Transient doping success . . . Materials - Transient doping success . . . Using a scanning tunneling microscope tip, scientists at the University of Rostock, Germany, and Oak Ridge National Laboratory have accomplished something thought to be virtually impossible. "We devised an approach to change electronic properties of one-dimensional systems without introducing dopant atoms that effectively cut the chain into smaller pieces," said Paul Snijders of ORNL's Materials Science and Technology Division. This discovery, known as transient doping and detailed in a paper published in Physical Review Letters, was accomplished using only electrons. That makes it especially intriguing to co-author Snijders and colleagues who note that the doping of materials, which changes the number of electrons, has led to

76

Elements of Doping Engineering in Semiconductors  

DOE Green Energy (OSTI)

Using defect thermodynamics, we discuss physical factors that affect doping limits in semiconductors. The dependencies of the defect formation enthalpy on the atomic chemical potentials and on the electron Fermi energy are demonstrated. These dependencies, in particular on the Fermi energy, lead to spontaneous formation of charge-compensating defects that can limit doping. Experimental data compiled for III-V, II-VI, and I-III-VI2 compounds support this view and further provide insight into the connections among different host materials. We argue that what matters is not the magnitude of the band gap that determines the dopability of a material, but rather, the relative position of the conduction-band minimum (in the case of n-doping) and the valence-band maximum (in the case of p-doping) with respect to vacuum.

Zhang, S. B.; Wei, S.; Zunger, A.

1998-11-09T23:59:59.000Z

77

Doped colloidal ZnO nanocrystals  

Science Conference Proceedings (OSTI)

Colloidal ZnO nanocrystals are promising for a wide range of applications due to the combination of unique multifunctional nature and remarkable solution processability. Doping is an effective approach of enhancing the properties of colloidal ZnO nanocrystals ...

Yizheng Jin; Yuping Ren; MoTao Cao; Zhizhen Ye

2012-01-01T23:59:59.000Z

78

Controlled doping of graphene using ultraviolet irradiation  

SciTech Connect

The electronic properties of graphene are tunable via doping, making it attractive in low dimensional organic electronics. Common methods of doping graphene, however, adversely affect charge mobility and degrade device performance. We demonstrate a facile shadow mask technique of defining electrodes on graphene grown by chemical vapor deposition (CVD) thereby eliminating the use of detrimental chemicals needed in the corresponding lithographic process. Further, we report on the controlled, effective, and reversible doping of graphene via ultraviolet (UV) irradiation with minimal impact on charge mobility. The change in charge concentration saturates at {approx}2 Multiplication-Sign 10{sup 12} cm{sup -2} and the quantum yield is {approx}10{sup -5} e/photon upon initial UV exposure. This simple and controlled strategy opens the possibility of doping wafer-size CVD graphene for diverse applications.

Luo Zhengtang [Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay (Hong Kong); Pinto, Nicholas J.; Davila, Yarely [Department of Physics and Electronics, University of Puerto Rico at Humacao, Humacao, 00792 (Puerto Rico); Charlie Johnson, A. T. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396 (United States)

2012-06-18T23:59:59.000Z

79

Crystallization mechanisms and recording characteristics of Si/CuSi bilayer for write-once blu-ray disc  

SciTech Connect

The crystallization mechanisms of Si/CuSi bilayer and its recording characteristics for write-once blu-ray disc (BD-R) were investigated. It was found that Cu{sub 3}Si phase appeared during the room temperature sputtered deposition. Then, the Si atoms in CuSi layer segregated and crystallized to cubic Si in Cu{sub 3}Si nucleation sites as the film was annealed at 270 deg. C. After heating to 500 deg. C, the grains size of cubic Si phase grew and the hexagonal Si phase was observed. The dynamic tests show that the Si/CuSi bilayer has great feasibility for 1-4x BD-R with the bottom jitter values below 6.5%.

Ou, Sin-Liang; Kuo, Po-Cheng; Tsai, Tsung-Lin [Departmant of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Sheng-Chi [Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, Taipei 243, Taiwan (China); Yeh, Chin-Yen; Chang, Han-Feng [CMC Magnetics Corporation, Taoyuan 333, Taiwan (China); Lee, Chao-Te; Chiang, Donyau [Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu 300, Taiwan (China)

2011-09-19T23:59:59.000Z

80

Metal-doped organic gels and method thereof  

DOE Patents (OSTI)

Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

Satcher, Jr., Joe H. (Patterson, CA); Baumann, Theodore F. (Tracy, CA)

2007-10-23T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Eribium Doped Y2O3  

NLE Websites -- All DOE Office Websites (Extended Search)

Effect of Local Coordination on the Photoluminescence Properties of Er-doped Effect of Local Coordination on the Photoluminescence Properties of Er-doped Y2O3 Thin Films Miniaturizing the erbium-doped optical fiber amplifier (~20 m in length) into a small, compact amplifier that can be integrated with other optical and electronic devices on a single chip (optoelectronics) offers great promise in optical communication as an alternative to the electronic technology.1,2, The gain of these miniaturized devices is limited by the solubility, concentration, and distribution of optically-active Er3+ in a host material. 3 While incorporation of a high concentration of erbium is possible by ion implantation, the method does not allow for the control of spatial distribution or the activation of the ions in the host. This is critical at high Er concentrations, since non-radiative processes resulting from ion-ion interactions become dominant and significantly reduce the photoluminescence (PL) yield.

82

Spectroscopic investigation of nitrogen doped graphene  

Science Conference Proceedings (OSTI)

Current research efforts are aimed at controlling the electronic properties via doping graphene. Previously, dopant-induced changes in the Fermi velocity were observed to result in an effectively downshifted Raman peak below the G Prime -band for n-doped carbon nanotubes. However, in the case of N-doped graphene, we find that several Raman features vary depending upon both dopant concentration and its bonding environment. For instance, only pyridinic/pyrrolic dopants were observed to result in intense D/D Prime -bands with a concomitant downshift in the G Prime -band. Here, we correlate x-ray photoelectron measurements with Raman spectra to elucidate effects of dopant bonding configuration on vibrational properties of graphene.

Podila, R.; Spear, J. T. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Chacon-Torres, J.; Pichler, T.; Ayala, P. [Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna (Austria); Rao, A. M. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Center for Optical Materials Science and Technology, Clemson University, Clemson, South Carolina 29634 (United States)

2012-09-17T23:59:59.000Z

83

Molecular doping of graphene with ammonium groups  

SciTech Connect

Successful doping of an electronic material entails the existence of stable dopant configurations that cause a shift in the Fermi level without altering significantly the electronic states of the host system. The selection of chemical groups that satisfy these conditions when adsorbed on graphene is still an open challenge. Here we show with first-principles calculations that ammonium groups meet the criteria of stable physisorption and efficient doping of graphene. We also describe processes of deactivation of ammonium dopants through their dissociation over graphene impurities or nanoribbon edges. Finally, we show that carbon nanotubes can be used to spatially confine the dopants and avert their edge-related de-activation.

Tsetseris, L. [Vanderbilt University; Pantelides, Sokrates T [ORNL

2012-01-01T23:59:59.000Z

84

Coexistence and competition of nematic and gapped states in bilayer graphene  

E-Print Network (OSTI)

In bilayer graphene, the phase diagram in the plane of a strain-induced bare nematic term, ${\\cal N}_{0}$, and a top-bottom gates voltage imbalance, $U_{0}$, is obtained by solving the gap equation in the random-phase approximation. At nonzero ${\\cal N}_0$ and $U_0$, the phase diagram consists of two hybrid spin-valley symmetry-broken phases with both nontrivial nematic and mass-type order parameters. The corresponding phases are separated by a critical line of first- and second-order phase transitions at small and large values of ${\\cal N}_0$, respectively. The existence of a critical end point, where the line of first-order phase transitions terminates, is predicted. For ${\\cal N}_0=0$, a pure gapped state with a broken spin-valley symmetry is the ground state of the system. As ${\\cal N}_{0}$ increases, the nematic order parameter increases, and the gap weakens in the hybrid state. For $U_{0}=0$, a quantum second-order phase transition from the hybrid state into a pure gapless nematic state occurs when the strain reaches a critical value. A nonzero $U_{0}$ suppresses the critical value of the strain. The relevance of these results to recent experiments is briefly discussed.

E. V. Gorbar; V. P. Gusynin; V. A. Miransky; I. A. Shovkovy

2012-04-10T23:59:59.000Z

85

Bilayer membranes in micro-fluidics: from gel emulsions to soft functional devices  

E-Print Network (OSTI)

We outline a concept of self-assembled soft matter devices based on micro-fluidics, which use surfactant bilayer membranes as their main building blocks, arrested in geometric structures provided by top-down lithography. Membranes form spontaneously when suitable water-in-oil emulsions are forced into micro-fluidic channels at high dispersed-phase volume fractions. They turn out to be remarkably stable even when pumped through the micro-fluidic channel system. Their geometric arrangement is self-assembling, driven by interfacial energy and wetting forces. The ordered membrane arrays thus emerging can be loaded with amphiphilic functional molecules, ion channels, or just be used as they are, exploiting their peculiar physical properties. For wet electronic circuitry, the aqueous droplets then serve as the 'solder points'. Furthermore, the membranes can serve as well-controlled coupling media between chemical processes taking place in adjacent droplets. This is shown for the well-known Belousov-Zhabotinski reaction. Suitable channel geometries can be used to (re-) arrange the droplets, and thereby their contents, in a controlled way by just moving the emulsion through the device. It thereby appears feasible to construct complex devices out of molecular-size components in a self-assembled, but well controlled manner.

Shashi Thutupalli; Stephan Herminghaus; Ralf Seemann

2010-08-11T23:59:59.000Z

86

Kinetics of an Inverse Temperature Transition Process and Its Application on Supported Lipid Bilayer  

E-Print Network (OSTI)

This dissertation focuses on the study of inverse temperature transition processes of the poly(N-isopropylacrylamide) (PNIPAM) and the elastin-like polypeptides (ELPs). A novel temperature jump microfluidic system is introduced and this system shows the ability to measure the kinetics of the PNIPAM and the ELPs collapse without a heat transfer problem. The conformational change of the ELPs during the phase transition process is utilized as a nanoscale protein filter to modulate ligandreceptor binding events on supported lipid bilayers (SLBs). This research study is divided into three main parts. The first part is the development of the temperature jump microfluidics. The kinetics of PNIPAM collapse is used as a model system to show the capability of this new device to measure millisecond time scale phase transition processes. The effects of salts on the kinetics of PNIPAM collapse are also shown in this part. To our knowledge, this is the first study which shows the effects of salts on PNIPAM collapse kinetics. The second part of this research is the application of the novel temperature jump microfluidics. The hydrophobic collapse of ELPs composed of identical sequence but different chain length is investigated. By controlling the molecular weight of the ELPs, the thermodynamic contributions from intermolecular hydrophobic interactions, and intramolecular hydrophobic interactions could be calculated individually for this unique system. The third part is the application of the phase transition property of ELPs. The ELPs are conjugated on the surface of the SLBs as a nanoscale protein filter. The conformation of the ELPs can be modulated by ionic strength of the buffer solution or ambient temperature. The ELPs conjugated SLBs platform showed the ability to block IgG binding to biotin conjugated on the SLBs when the ELPs were in the extended coil state and open the access for protein to bind to biotin in compact globule conformation.

Chang, Chin-Yuan

2010-08-01T23:59:59.000Z

87

Origins of the Doping Asymmetry in Oxides: Hole Doping in NiO versus Electron Doping in ZnO  

Science Conference Proceedings (OSTI)

The doping response of the prototypical transparent oxides NiO (p-type), ZnO (n-type), and MgO (insulating) is caused by spontaneous formation of compensating centers, leading to Fermi-level pinning at critical Fermi energies. We study the doping principles in these oxides by first-principles calculations of carrier-producing or -compensating defects and of the natural band offsets, and identify the dopability trends with the ionization potentials and electron affinities of the oxides. We find that the room-temperature free-hole density of cation-deficient NiO is limited by a too large ionization energy of the Ni vacancy, but it can be strongly increased by extrinsic dopants with shallower acceptor levels.

Lany, S.; Osorio-Guillen, J.; Zunger, A.

2007-01-01T23:59:59.000Z

88

Time-of-Flight Bragg Scattering from Aligned Stacks of Lipid Bilayers using the Liquids Reflectometer at the Spallation Neutron Source  

Science Conference Proceedings (OSTI)

Time-of-flight (TOF) neutron diffraction experiments on aligned stacks of lipid bilayers using the horizontal Liquids Reflectometer at the Spallation Neutron Source are reported. Specific details are given regarding the instrumental setup, data collection and reduction, phase determination of the structure factors, and reconstruction of the one-dimensional neutron scattering length density (NSLD) profile. The validity of using TOF measurements to determine the one-dimensional NSLD profile is demonstrated by reproducing the results of two well known lipid bilayer structures. The method is then applied to show how an antimicrobial peptide affects membranes with and without cholesterol.

Pan, Jianjun [ORNL; Heberle, Frederick A [ORNL; Carmichael, Justin R [ORNL; Ankner, John Francis [ORNL; Katsaras, John [ORNL

2012-01-01T23:59:59.000Z

89

Combustion Synthesis of Doped Thermoelectric Oxides  

Science Conference Proceedings (OSTI)

Self-propagating high-temperature synthesis (SHS) was used to prepare silver doped calcium cobaltates (Ca1.24- xAgxCo1.62O3.86, x = 0.03 - 0.12) powders. SHS is a simple and economic process to synthesize ceramic materials with minimum energy requirements. The heat generated by the SHS reaction can sustain the propagation of the reaction front and convert reactants to desired products. The effect of doping level on thermoelectric properties was investigated in this study. Results show the substitution of calcium by silver decreases the thermal conductivity significantly. XRD and surface area measurements show synthesized powders are phase pure and have large specific surface areas.

Selig, Jiri [Lamar University; Lin, Sidney [Lamar University; Lin, Hua-Tay [ORNL; Johnson, D Ray [ORNL

2012-01-01T23:59:59.000Z

90

Aluminum doped zinc oxide for organic photovoltaics  

Science Conference Proceedings (OSTI)

Aluminum doped zinc oxide (AZO) was grown via magnetron sputtering as a low-cost alternative to indium tin oxide (ITO) for organic photovoltaics (OPVs). Postdeposition ozone treatment resulted in devices with lower series resistance, increased open-circuit voltage, and power conversion efficiency double that of devices fabricated on untreated AZO. Furthermore, cells fabricated using ozone treated AZO and standard ITO displayed comparable performance.

Murdoch, G. B.; Hinds, S.; Sargent, E. H.; Tsang, S. W.; Mordoukhovski, L.; Lu, Z. H. [Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario M5S 3E4 (Canada)

2009-05-25T23:59:59.000Z

91

High active carrier concentration in n-type, thin film Ge using delta-doping  

E-Print Network (OSTI)

We demonstrate CVD in situ doping of Ge by utilizing phosphorus delta-doping for the creation of a high dopant diffusion source. Multiple monolayer delta doping creates source phosphorous concentrations above 1 × 10[superscript ...

Cai, Yan

92

Substrate and method for the formation of continuous magnesium diboride and doped magnesium diboride wire  

DOE Patents (OSTI)

A chemically doped boron coating is applied by chemical vapor deposition to a silicon carbide fiber and the coated fiber then is exposed to magnesium vapor to convert the doped boron to doped magnesium diboride and a resultant superconductor.

Suplinskas, Raymond J. (Haverhill, MA); Finnemore, Douglas (Ames, IA); Bud' ko, Serquei (Ames, IA); Canfield, Paul (Ames, IA)

2007-11-13T23:59:59.000Z

93

Influence of Si Co-doping on electrical transport properties of magnesium-doped boron nanoswords  

Science Conference Proceedings (OSTI)

Magnesium-doped boron nanoswords were synthesized via a thermoreduction method. The as-prepared nanoswords are single crystalline and {beta}-rhombohedral ({beta}-rh) phase. Electrical transport measurements show that variable range hopping conductivity increases with temperature, and carrier mobility has a greater influence than carrier concentration. These results are consistent with the three dimensional Mott's model (M. Cutler and N. F. Mott, Phys. Rev. 181, 1336 (1969)) besides a high density of localized states at the Fermi level compared with bulk {beta}-rh boron. Conductivity of Mg-doped boron nanoswords is significantly lower than that of ''pure'' (free of magnesium) boron nanoswords. Electron energy loss spectroscopy studies confirm that the poorer conductivity arises from silicon against magnesium doping.

Tian Yuan; Lu Hongliang; Tian Jifa; Li Chen; Hui Chao; Shi Xuezhao; Huang Yuan; Shen Chengmin; Gao Hongjun [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2012-03-05T23:59:59.000Z

94

More Efficient Polymer Solar Cells by Doping with Ferroelectric ...  

Science Conference Proceedings (OSTI)

Presentation Title, More Efficient Polymer Solar Cells by Doping with ... Mixture for Predicting the Ideal Solubility of Thermally Stable and Unstable Compounds.

95

Aluminum-doped Zinc Oxide Nanoink - Energy Innovation Portal  

Scientists at Berkeley Lab have developed a method for fabricating conductive aluminum-doped zinc oxide (AZO) nanocrystals that provide a lower cost, less toxic ...

96

Development of Economically Doped Heat-Resistant Nickel Single ...  

Science Conference Proceedings (OSTI)

Presentation Title, Development of Economically Doped Heat-Resistant Nickel Single-Crystal Superalloys for Blades of Perspective Gas Turbine Engines.

97

Plasma process optimization for N-type doping applications  

SciTech Connect

Plasma doping (PLAD) has been adopted across the implant technology space and into high volume production for both conventional DRAM and NAND doping applications. PLAD has established itself as an alternative to traditional ion implantation by beamline implantation. The push for high doping concentration, shallow doping depth, and conformal doping capability expand the need for a PLAD solution to meet such requirements. The unique doping profile and doping characteristics at high dose rates allow for PLAD to deliver a high throughput, differentiated solution to meet the demand of evolving transistor technology. In the PLAD process, ions are accelerated to the wafer as with a negative wafer bias applied to the wafer. Competing mechanisms, such as deposition, sputtering, and etching inherent in plasma doping require unique control and process optimization. In this work, we look at the distinctive process tool control and characterization features which enable an optimized doping process using n-type (PH{sub 3} or AsH{sub 3}) chemistries. The data in this paper will draw the relationship between process optimization through plasma chemistry study to the wafer level result.

Raj, Deven; Persing, Harold; Salimian, Siamak; Lacey, Kerry; Qin Shu; Hu, Jeff Y.; McTeer, Allen [Applied Materials, Inc., Varian Semiconductor Business Unit, 35 Dory Road, Gloucester, MA 01930 (United States); Micron Technology, Inc., 8000 S. Federal Way, Boise, ID 83707 (United States)

2012-11-06T23:59:59.000Z

98

CNST Collaboration Models Ionic Conductivity in Doped Ceria ...  

Science Conference Proceedings (OSTI)

... K to 1073 K) that are practical for fuel cell operation. Compared with the electrolytes that are commonly used in solid oxide fuel cells, doped ceria ...

2013-05-15T23:59:59.000Z

99

Rare Earth and Plutonium Doping of Apatite - Programmaster.org  

Science Conference Proceedings (OSTI)

Presentation Title, Rare Earth and Plutonium Doping of Apatite ... Influence of Cation Composition and Temperature on the Solubility and Oxidation State of Ce  ...

100

Lithium/Sulfur Batteries Based on Doped Mesoporous Carbon ...  

A sulfur/carbon composite material was prepared by heat treatment of doped mesoporous carbon and elemental sulfur at a temperature inside a stainless steel vessel ...

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Microstructural Investigation of Nano-Calcium Phosphates Doped ...  

Science Conference Proceedings (OSTI)

Presentation Title, Microstructural Investigation of Nano-Calcium Phosphates Doped with Fluoride Ions. Author(s), Aydin Tahmasebifar, Zafer Evis, Serap ...

102

Ultrafast thin-film laser-induced breakdown spectroscopy of doped...  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast thin-film laser-induced breakdown spectroscopy of doped oxides Title Ultrafast thin-film laser-induced breakdown spectroscopy of doped oxides Publication Type Journal...

103

Silicon-containing copolymers of MMA tested for a positive-tone high-resolution bi-layer e-beam resist system  

Science Conference Proceedings (OSTI)

Copolymers of methylmethacrylate (MMA) and trimethylsilyl-methylmethacrylate (SiMMA) in various molar ratios have been synthesised and characterised for use as a resist in electron beam lithography. The development procedure has been optimised in terms ... Keywords: Bi-layer system, Electron beam lithography, Resist, Silicon-loaded PMMA

J. Maessen; S. van den Boogaart; E. J. K. Verstegen; J. G. Kloosterboer; F. C. M. J. M. van Delft; W. Catsburg; F. H. P. M. Habraken

2005-03-01T23:59:59.000Z

104

Molecular dynamics simulation of complex molecules at interfaces: dendritic surfactants in clay and amyloid peptides near lipid bilayers  

E-Print Network (OSTI)

We apply a molecular dynamics (MD) simulation technique to complex molecules at interfaces. Partitioning of dendritic surfactants into clay gallery and Ab protein behavior near hydrated lipids are chosen for the purpose. Using a full atomistic model of dendritic surfactants, the confinement force profiles featuring oscillatory fashion at moderate layer separation of 10 to 25 Å were observed. Integration of the confinement forces led to free energy profiles, which, in turn, were used to determine the final morphology of the nanocomposite. From the free energy profiles, smaller and linear surfactants (G1 and G2L) are expected to intercalate into the clay comfortably, while larger surfactants (G2 and G3) are expected to form frustrated intercalated structures due to the location and depth of the free energy minima. This would agree with the previous observations. As primary steps to understand the Ab protein behavior under biological conditions, simulations of bulk water and hydrated lipids were performed and the results were compared with the literature. Hydrated lipids were simulated using a full atomistic model of lipids (dipalmitoylphosphatidylcholine) and water with a cvff force-field and it was found that structural properties such as the molecular head group area and membrane thickness were accurately produced with MD simulation. Systems of the protein Ab(1-42) in bulk water were simulated and some secondary structural change, with loss of part of the a-helical structure, occurred during the 1 ns of simulation time at 323K. The fragment Ab(31-42) with b-sheet conformation was also simulated in bulk water, and the extended b-sheet structure became a bent structure. Simulations of Ab(1- 42) or Ab(31-42) near lipid bilayers have been performed to investigate the structural property changes under biological conditions. The different nature of structural change was observed from the simulations of the protein or fragment in water and near lipid bilayers due to the different solvent environment. The protein has close contacts with the membrane surface. It was impossible to observe the conformational change to b-sheet and protein entrance into the lipid bilayer within 1 ns simulations.

Han, Kunwoo

2006-08-01T23:59:59.000Z

105

Superlattice doped layers for amorphous silicon photovoltaic cells  

DOE Patents (OSTI)

Superlattice doped layers for amorphous silicon photovoltaic cells comprise a plurality of first and second lattices of amorphous silicon alternatingly formed on one another. Each of the first lattices has a first optical bandgap and each of the second lattices has a second optical bandgap different from the first optical bandgap. A method of fabricating the superlattice doped layers also is disclosed.

Arya, Rajeewa R. (Doylestown, PA)

1988-01-12T23:59:59.000Z

106

Optical Properties and Potential Applications of Doped Semiconductor Nanoparticles  

SciTech Connect

Recent studies on the optical properties, in particular luminescence, of a variety of doped semiconductor nanoparticles are reviewed. The effects of quantum confinement, temperature, and pressure on luminescent properties are discussed. In addition, electroluminescence, cathodoluminescence, magnetoluminescence and related applications involving doped semiconductor nanoparticles are presented. A new phenomenon, upconversion luminescence of doped nanoparticles, is reviewed and its potential applications are discussed. While more research efforts are necessary in order to fully understand the fundamentals and explore the great technological potential behind doped nanoparticles, recent results already show that this is a new and exciting field with applications in many fields. In particular, the emerging field of ''spintronics'', where spin states are exploited in analogy to conventional electronic states, is discussed and the advantages of using doped semiconductor nanoparticles are elucidated.

Chen, Wei; Zhang, Jin Z.; Joly, Alan G.

2004-11-08T23:59:59.000Z

107

Scintillation of rare earth doped fluoride nanoparticles  

SciTech Connect

The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

2011-09-12T23:59:59.000Z

108

Transition-metal-doped chalcogenide lasers  

Science Conference Proceedings (OSTI)

Broadly tunable mid-infrared lasers are desirable for a number of scientific, remote-sensing, and military applications. Recently, Cr2+-doped chalcogenide lasers have emerged as an attractive source of tunable laser radiation in the 2-3.4-µm ... Keywords: Cr:CdMnTe, Cr:CdSe, Cr:ZnS, Cr:ZnSe, Fe:ZnSe, chalcogenide, continuous-wave laser, diode-pumped solid-state laser, mode-locked laser, solid-state laser, transition-metal ion

Timothy J. Carrig

2002-07-01T23:59:59.000Z

109

Transformation-optics generalization of tunnelling effects in bi-layers made of paired epsilon-negative/mu-negative media  

E-Print Network (OSTI)

Transformation-media designed by standard transformation-optics (TO) approaches, based on real-valued coordinate-mapping, cannot exhibit single-negative (SNG) character unless such character is already possessed by the domain that is being transformed. In this paper, we show that SNG transformation media can be obtained by transforming a domain featuring double positive (or double-negative) character, via complex analytic continuation of the coordinate transformation rules. Moreover, we apply this concept to the TO-based interpretation of phenomena analogous to the tunnelling effects observable in bilayers made of complementary epsilon-negative (ENG) and mu-negative (MNG) media, and explore their possible TO-inspired extensions and generalizations.

Castaldi, Giuseppe; Galdi, Vincenzo; Alu', Andrea; Engheta, Nader

2010-01-01T23:59:59.000Z

110

Color stable manganese-doped phosphors  

DOE Patents (OSTI)

A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

Lyons, Robert Joseph (Burnt Hills, NY); Setlur, Anant Achyut (Niskayuna, NY); Deshpande, Anirudha Rajendra (Twinsburg, OH); Grigorov, Ljudmil Slavchev (Sofia, BG)

2012-08-28T23:59:59.000Z

111

Surface doping of nitrogen atoms on graphene via molecular precursor  

SciTech Connect

Surface doping can be a powerful way to modify the electronic properties of graphene with the unique potential to retain the excellent pristine properties of graphene. Here, we report an atomic surface doping method for graphene via dissociation of adsorbed precursor molecules of tetrafluorotetracyanoquinodimethane (F{sub 4}-TCNQ) induced by hydrogen plasma treatment. Significantly, the location of the dopant N atoms can be pre-determined by the location and orientation of the F{sub 4}-TCNQ molecule precursor on graphene, leading in principle to site-selective doping. Furthermore, the molecular precursor is stable under ambient conditions, satisfying an important consideration for patterning processes.

Hong, Guo; Wu, Qi-Hui; Ren, Jianguo; Xu, Tingting [Institution of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory of Carbon-based Functional Materials and Devices, Soochow University, Jiangsu (China) [Institution of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory of Carbon-based Functional Materials and Devices, Soochow University, Jiangsu (China); Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong (China); Wang, Chundong; Zhang, Wenjun [Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong (China)] [Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong (China); Lee, Shuit-Tong [Institution of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory of Carbon-based Functional Materials and Devices, Soochow University, Jiangsu (China)] [Institution of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory of Carbon-based Functional Materials and Devices, Soochow University, Jiangsu (China)

2013-02-04T23:59:59.000Z

112

A Drift-Diffusion-Reaction Model for Excitonic Photovoltaic Bilayers: Asymptotic Analysis and A 2-D HDG Finite-Element Scheme  

E-Print Network (OSTI)

We present and discuss a mathematical model for the operation of bilayer organic photovoltaic devices. Our model couples drift-diffusion-recombination equations for the charge carriers (specifically, electrons and holes) with a reaction-diffusion equation for the excitons/ polaron pairs and Poisson's equation for the self-consistent electrostatic potential. The material difference (i.e. the HOMO/LUMO gap) of the two organic substrates forming the bilayer device are included as a work-function potential. Firstly, we perform an asymptotic analysis of the scaled one-dimensional stationary state system i) with focus on the dynamics on the interface and ii) with the goal of simplifying the bulk dynamics away for the interface. Secondly, we present a twodimensional Hybrid Discontinuous Galerkin Finite Element numerical scheme which is very well suited to resolve i) the material changes ii) the resulting strong variation over the interface and iii) the necessary upwinding in the discretization of drift-diffusion equ...

Brinkman, Daniel; Markowich, Peter A; Wolfram, Marie-Therese

2012-01-01T23:59:59.000Z

113

Molecular beam epitaxy growth of exchange-biased PtMn/NiFe bilayers with a spontaneously ordered PtMn layer  

Science Conference Proceedings (OSTI)

We report the direct epitaxial growth of equiatomic ordered antiferromagnetic PtMn layers by molecular beam epitaxy. Such layers are used in giant magnetoresistance spin valve sensors as the antiferromagnetic pinning layer. Structural characterization and phase identification confirmed the spontaneous formation of the chemically ordered face-centered-tetragonal (L1{sub 0}) phase of PtMn with about 87.4% ordering. Based on the antiferromagnetic PtMn layer, we prepared exchange-biased PtMn/NiFe bilayers with various PtMn thicknesses. The exchange anisotropy field of the bilayer with NiFe grown on PtMn stabilizes at about 50 Oe beyond a PtMn thickness of 15 nm. Although the exchange anisotropy field is small compared to that of the polycrystalline system, the antiferromagnetic domain structure is stable over repetitive external magnetic field cycling and no training effect is observed.

Choi, Y. S.; Petford-Long, A. K.; Ward, R. C. C.; Fan, R.; Goff, J. P.; Hase, T. P. A. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Department of Physics, University of Durham, Durham DH1 3LE (United Kingdom)

2006-04-15T23:59:59.000Z

114

Muon spin depolarization in nonmagnetic metals doped with paramagnetic impurities  

Science Conference Proceedings (OSTI)

The diffusion of muons and their magnetic interactions are treated by describing the physics to be learned from experiments which measure muon depolarization in metallic hosts doped with dilute concentrations of magnetic impurities. (GHT)

Heffner, R.H.

1980-01-01T23:59:59.000Z

115

Electrical Properties and Sintering Characteristics of Bi-Doped ...  

Science Conference Proceedings (OSTI)

... Properties and Sintering Characteristics of Bi-Doped Gd2Zr2O7 Powders. Author(s), Jose A. Diaz-Guillen, Esmeralda Mendoza-Mendoza, Antonio F. Fuentes.

116

Fluorine compounds for doping conductive oxide thin films  

DOE Patents (OSTI)

Methods of forming a conductive fluorine-doped metal oxide layer on a substrate by chemical vapor deposition are described. The methods may include heating the substrate in a processing chamber, and introducing a metal-containing precursor and a fluorine-containing precursor to the processing chamber. The methods may also include adding an oxygen-containing precursor to the processing chamber. The precursors are reacted to deposit the fluorine-doped metal oxide layer on the substrate. Methods may also include forming the conductive fluorine-doped metal oxide layer by plasma-assisted chemical vapor deposition. These methods may include providing the substrate in a processing chamber, and introducing a metal-containing precursor, and a fluorine-containing precursor to the processing chamber. A plasma may be formed that includes species from the metal-containing precursor and the fluorine-containing precursor. The species may react to deposit the fluorine-doped metal oxide layer on the substrate.

Gessert, Tim; Li, Xiaonan; Barnes, Teresa M; Torres, Jr., Robert; Wyse, Carrie L

2013-04-23T23:59:59.000Z

117

Chiral superconductivity from repulsive interactions in doped graphene  

E-Print Network (OSTI)

Chiral superconductivity, which breaks time-reversal symmetry, can exhibit a wealth of fascinating properties that are highly sought after for nanoscience applications. We identify doped graphene monolayer as a system where ...

Chubukov, A. V.

118

Phase transformation and crystallization kinetics of a-Ge/Cu bilayer for blue-ray recording under thermal annealing and pulsed laser irradiation  

SciTech Connect

Similar phase formation and crystallization behaviors have been observed in the a-Ge/Cu bilayer under thermal annealing and pulsed laser irradiation. The Cu{sub 3}Ge phase would form prior to the crystallization of a-Ge. The crystallization temperature and activation energy for crystallization of a-Ge were reduced to 310 deg. C and 2.75 eV, respectively, due to the fast Ge diffusion in the already formed germanide phases. The reaction exponent m of {approx}2.0 for the a-Ge/Cu bilayer corresponds to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of the grain growth process. Under pulsed laser irradiation, the maximum data-transfer-rates of 44, 56, 74, and 112 Mbit/s can be achieved in the write-once blue-ray disk at the recording powers of 3, 4, 5, and 6 mW, respectively. The a-Ge/Cu bilayer also demonstrated sufficient optical contrast and adequate absorptance for low power and high speed write-once blue-ray recording.

Her, Yung-Chiun; Tu, Wei-Ting; Tsai, Ming-Hsin [Department of Materials Science and Engineering, National Chung Hsing University, Taichung, Taiwan 40254 (China)

2012-02-15T23:59:59.000Z

119

Trench process and structure for backside contact solar cells with polysilicon doped regions  

DOE Patents (OSTI)

A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. An interrupted trench structure separates the P-type doped region from the N-type doped region in some locations but allows the P-type doped region and the N-type doped region to touch in other locations. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. Among other advantages, the resulting solar cell structure allows for increased efficiency while having a relatively low reverse breakdown voltage.

De Ceuster, Denis; Cousins, Peter John; Smith, David D

2013-05-28T23:59:59.000Z

120

Trench process and structure for backside contact solar cells with polysilicon doped regions  

SciTech Connect

A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. An interrupted trench structure separates the P-type doped region from the N-type doped region in some locations but allows the P-type doped region and the N-type doped region to touch in other locations. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. Among other advantages, the resulting solar cell structure allows for increased efficiency while having a relatively low reverse breakdown voltage.

De Ceuster, Denis (Woodside, CA); Cousins, Peter John (Menlo Park, CA); Smith, David D. (Campbell, CA)

2010-12-14T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Monte Carlo Study of Strongly-Interacting Degenerate Fermions: a Model for Voltage-Biased Bilayer Graphene  

E-Print Network (OSTI)

We formulate a model of N_f=4 flavors of relativistic fermion in 2+1d in the presence of a chemical potential mu coupled to two flavor doublets with opposite sign, akin to isopsin chemical potential in QCD. This is argued to be an effective theory for low energy electronic excitations in bilayer graphene, in which an applied voltage between the layers ensures equal populations of particles on one layer and holes on the other. The model is then reformulated on a spacetime lattice using staggered fermions, and in the absence of a sign problem, simulated using an orthodox hybrid Monte Carlo algorithm. With the coupling strength chosen to be close to a quantum critical point believed to exist for N_f

Wes Armour; Simon Hands; Costas Strouthos

2013-02-01T23:59:59.000Z

122

Sonochemical synthesis of Er3+-doped ZnO nanospheres with enhanced upconversion photoluminescence  

Science Conference Proceedings (OSTI)

Er3+-doped ZnO nanospheres have been synthesized via a sonochemical conversion process. The formation mechanism of these nanocrystals is connected with the sonochemical effect of ultrasound irradiation. The as-prepared Er3+ doped ...

Jun Geng, Guang-Hui Song, Jun-Jie Zhu

2012-01-01T23:59:59.000Z

123

Iron (III) Chloride doping of large-area chemical vapor deposition graphene  

E-Print Network (OSTI)

Chemical doping is an effective method of reducing the sheet resistance of graphene. This thesis aims to develop an effective method of doping large area Chemical Vapor Deposition (CVD) graphene using Iron (III) Chloride ...

Song, Yi, S.M. Massachusetts Institute of Technology

2013-01-01T23:59:59.000Z

124

Fe-doped InN layers grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Iron(Fe)-doped InN (InN:Fe) layers have been grown by molecular beam epitaxy. It is found that Fe-doping leads to drastic increase of residual electron concentration, which is different from the semi-insulating property of Fe-doped GaN. However, this heavy n-type doping cannot be fully explained by doped Fe-concentration ([Fe]). Further analysis shows that more unintentionally doped impurities such as hydrogen and oxygen are incorporated with increasing [Fe] and the surface is degraded with high density pits, which probably are the main reasons for electron generation and mobility reduction. Photoluminescence of InN is gradually quenched by Fe-doping. This work shows that Fe-doping is one of good choices to control electron density in InN.

Wang Xinqiang; Liu Shitao; Ma Dingyu; Zheng Xiantong; Chen Guang; Xu Fujun; Tang Ning; Shen Bo [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Zhang Peng; Cao Xingzhong; Wang Baoyi [State Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Huang Sen; Chen, Kevin J. [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology (Hong Kong); Zhou Shengqiang [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01314 Dresden (Germany); Yoshikawa, Akihiko [Center for SMART Green Innovation Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

2012-10-22T23:59:59.000Z

125

Structural and electrical properties of trimethylboron-doped silicon nanowires  

SciTech Connect

Trimethylboron (TMB) was investigated as a p-type dopant source for the vapor-liquid-solid growth of boron-doped silicon nanowires (SiNWs). The boron concentration in the nanowires was measured using secondary ion mass spectrometry and results were compared for boron-doping using TMB and diborane (B{sub 2}H{sub 6}) sources. Boron concentrations ranging from 1x10{sup 18} to 4x10{sup 19} cm{sup -3} were obtained by varying the inlet dopant/SiH{sub 4} gas ratio. TEM characterization revealed that the B{sub 2}H{sub 6}-doped SiNWs consisted of a crystalline core with a thick amorphous Si coating, while the TMB-doped SiNWs were predominantly single crystal even at high boron concentrations. The difference in structural properties was attributed to the higher thermal stability and reduced reactivity of TMB compared to B{sub 2}H{sub 6}. Four-point resistivity and gate-dependent conductance measurements were used to confirm p-type conductivity in the TMB-doped nanowires and to investigate the effect of dopant concentration on nanowire resistivity.

Lew, K.-K.; Pan Ling; Bogart, Timothy E.; Dilts, Sarah M.; Dickey, Elizabeth C.; Redwing, Joan M.; Wang Yanfeng; Cabassi, Marco; Mayer, Theresa S.; Novak, Steven W. [Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Evans East, East Windsor, New Jersey 08520 (United States)

2004-10-11T23:59:59.000Z

126

Optimal doping control of magnetic semiconductors via subsurfactant epitaxy  

SciTech Connect

Dilute magnetic semiconductors (DMS) with high ferromagnetic ordering temperatures (T{sub c}) have vast potential for advancing spin-based electronics or 'spintronics'. To date, achieving high-T{sub c} DMS typically required doping levels of order 5%. Such high doping levels inevitably compromise the structural homogeneity and carrier mobility of the DMS. Here, we establish 'subsurfactant epitaxy' as a novel kinetic pathway for synthesizing Mn-doped germanium with T{sub c} much higher than room temperature, at dramatically reduced doping levels. This is accomplished by optimal control of the diffusion kinetics of the dopant atoms near the growth front in two separate deposition steps. The first involves a submonolayer dose of Mn on Ge(100) at low temperature, which populates subsurface interstitial sites with Mn while suppressing lateral Mn diffusion and clustering. The second step involves epitaxial growth of Ge at elevated temperature, taking advantage of the strong floating ability of the interstitial Mn dopants towards the newly defined subsurface sites at the growth front. Most remarkably, the Mn dopants trapped inside the film are uniformly distributed at substitutional sites, and the resulting film exhibits ferromagnetism above 400 K at the nominal doping level of only 0.2%.

Zeng, Changgan [ORNL; Zhang, Zhenyu [ORNL; van Benthem, Klaus [ORNL; Chisholm, Matthew F [ORNL; Weitering, Harm H [ORNL

2008-01-01T23:59:59.000Z

127

Young's modulus evaluation by SAWs for porous silica low-k film with cesium doping  

Science Conference Proceedings (OSTI)

Young's moduli of porous silica low-k films with cesium (Cs) doping are determined by surface acoustic waves (SAWs) in this study. Four low-k samples doped with 0-30ppmwt% Cs in the precursor solution are investigated to check the mechanical promotion ... Keywords: Cesium doping, Low-k film, Porous silica, Surface acoustic waves, Young's modulus

X. Xiao; X. M. Shan; Y. Kayaba; K. Kohmura; H. Tanaka; T. Kikkawa

2011-05-01T23:59:59.000Z

128

Interplay of superconductivity and spin-density-wave order in doped graphene  

E-Print Network (OSTI)

We study the interplay between superconductivity and spin-density-wave order in graphene doped to 3/8 or 5/8 filling (a van Hove doping). At this doping level, the system is known to exhibit weak-coupling instabilities to ...

Chubukov, Andrey V.

129

Study of the P-type doping properties of ZnS nanocrystals  

Science Conference Proceedings (OSTI)

The paper presents the study of p-type doping properties of ZnS nanocrystals (Ncs) using the local density approximation theory (LDA). Doping with single species of N, P, or As, ZnS nanocrystals are found to have a low-doping concentration and efficiency, ...

Xiying Ma

2011-01-01T23:59:59.000Z

130

Photorefractive effect at 775 nm in doped lithium niobate crystals  

SciTech Connect

The photorefractive effect induced by 775-nm laser light on doped lithium niobate crystals is investigated by the direct observation in the far field of the transmitted-beam distortion as a function of time. Measurements performed at various Zr-doping concentrations and different light intensities show that the 775-nm light beam induces a steady-state photorefractive effect comparable to that of 532-nm light, but the observed build-up time of the photovoltaic field is longer by three-orders of magnitude. The 775-nm photorefractivity of lithium niobate crystals doped with 3 mol. % ZrO{sub 2} or with 5.5 mol. % MgO is found to be negligible.

Nava, G.; Minzioni, P.; Cristiani, I.; Degiorgio, V. [Department of Electrical, Computer, and Biomedical Engineering, and CNISM, University of Pavia, 27100 Pavia (Italy); Argiolas, N.; Bazzan, M.; Ciampolillo, M. V.; Pozza, G.; Sada, C. [Physics and Astronomy Departement, University of Padova, 35131 Padova (Italy)

2013-07-15T23:59:59.000Z

131

Magic Doping Fractions in High-Temperature Superconductors  

Science Conference Proceedings (OSTI)

We report hole-doping dependence of the in-plane resistivity {rho}{sub ab} in a cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4}, carefully examined using a series of high-quality single crystals. Our detailed measurements find a tendency towards charge ordering at particular rational hole doping fractions of 1/16, 3/32, 1/8, and 3/16. This observation appears to suggest a specific form of charge order and is most consistent with the recent theoretical prediction of the checkerboard-type ordering of the Cooper pairs at rational doping fractions x = (2m + 1)/2{sup n}, with integers m and n.

Komiya, Seiki; /CRIEPI, Tokyo; Chen, Han-Dong; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.; Ando, Yoichi; /CRIEPI, Tokyo

2010-01-15T23:59:59.000Z

132

Engineering shallow spins in diamond with nitrogen delta-doping  

SciTech Connect

We demonstrate nanometer-precision depth control of nitrogen-vacancy (NV) center creation near the surface of synthetic diamond using an in situ nitrogen delta-doping technique during plasma-enhanced chemical vapor deposition. Despite their proximity to the surface, doped NV centers with depths (d) ranging from 5 to 100 nm display long spin coherence times, T{sub 2} > 100 {mu}s at d = 5 nm and T{sub 2} > 600 {mu}s at d {>=} 50 nm. The consistently long spin coherence observed in such shallow NV centers enables applications such as atomic-scale external spin sensing and hybrid quantum architectures.

Ohno, Kenichi; Joseph Heremans, F.; Bassett, Lee C.; Myers, Bryan A.; Toyli, David M.; Bleszynski Jayich, Ania C.; Palmstrom, Christopher J.; Awschalom, David D. [Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106 (United States)

2012-08-20T23:59:59.000Z

133

Atomic hydrogen adsorption on lithium-doped graphite surfaces  

SciTech Connect

The effects of lithium doping of pristine and defective graphite surfaces on hydrogen adsorption are studied by the first-principles Plane-Wave Density Functional Theory. The surface defects are simulated by a single atomic vacancy. The DFT calculation is corrected for long-range effects through semi-empirical London terms for each constituent of the system. The lithium doping of the graphite surfaces notably reinforces hydrogen atom binding. Qualitative comparison with experimental results is given using the lithium 1s energy level shifts induced by the atomic vacancy and/or hydrogen trapping.

Allouche, Alain [CNRS/Univ. de Provence (France); Krstic, Predrag S [ORNL

2012-01-01T23:59:59.000Z

134

Doping of carbon foams for use in energy storage devices  

DOE Patents (OSTI)

A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located there between. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery. 3 figs.

Mayer, S.T.; Pekala, R.W.; Morrison, R.L.; Kaschmitter, J.L.

1994-10-25T23:59:59.000Z

135

Doping of carbon foams for use in energy storage devices  

SciTech Connect

A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located therebetween. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery.

Mayer, Steven T. (San Leandro, CA); Pekala, Richard W. (Pleasant Hill, CA); Morrison, Robert L. (Modesto, CA); Kaschmitter, James L. (Pleasanton, CA)

1994-01-01T23:59:59.000Z

136

Single-poly EEPROM cell with lightly doped MOS capacitors  

DOE Patents (OSTI)

An Electrically Erasable Programmable Read Only Memory (EEPROM) memory cell and a method of operation are disclosed for creating an EEPROM memory cell in a standard CMOS process. A single polysilicon layer is used in combination with lightly doped MOS capacitors. The lightly doped capacitors employed in the EEPROM memory cell can be asymmetrical in design. Asymmetrical capacitors reduce area. Further capacitance variation caused by inversion can also be reduced by using multiple control capacitors. In addition, the use of multiple tunneling capacitors provides the benefit of customized tunneling paths.

Riekels, James E. (New Hope, MN); Lucking, Thomas B. (Maple Grove, MN); Larsen, Bradley J. (Mound, MN); Gardner, Gary R. (Golden Valley, MN)

2008-05-27T23:59:59.000Z

137

Excellent Passivation and Low Reflectivity Al2O3/TiO2 Bilayer Coatings for n-Wafer Silicon Solar Cells: Preprint  

DOE Green Energy (OSTI)

A bilayer coating of Al2O3 and TiO2 is used to simultaneously achieve excellent passivation and low reflectivity on p-type silicon. This coating is targeted for achieving high efficiency n-wafer Si solar cells, where both passivation and anti-reflection (AR) are needed at the front-side p-type emitter. It could also be valuable for front-side passivation and AR of rear-emitter and interdigitated back contact p-wafer cells. We achieve high minority carrier lifetimes {approx}1 ms, as well as a nearly 2% decrease in absolute reflectivity, as compared to a standard silicon nitride AR coating.

Lee, B. G.; Skarp, J.; Malinen, V.; Li, S.; Choi, S.; Branz, H. M.

2012-06-01T23:59:59.000Z

138

Boron-doped back-surface fields using an aluminum-alloy process  

DOE Green Energy (OSTI)

Boron-doped back-surface fields (BSF`s) have potentially superior performance compared to aluminum-doped BSF`s due to the higher solid solubility of boron compared to aluminum. However, conventional boron diffusions require a long, high temperature step that is both costly and incompatible with many photovoltaic-grade crystalline-silicon materials. We examined a process that uses a relatively low-temperature aluminum-alloy process to obtain a boron-doped BSF by doping the aluminum with boron. In agreement with theoretical expectations, we found that thicker aluminum layers and higher boron doping levels improved the performance of aluminum-alloyed BSF`s.

Gee, J.M.; Bode, M.D.; Silva, B.L.

1997-10-01T23:59:59.000Z

139

Ce-doped EuO: Magnetic properties and the indirect band gap  

Science Conference Proceedings (OSTI)

We have prepared and investigated thin films of EuO doped with the rare-earth element cerium. X-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectroscopy were used to determine the quality of these films prepared by pulsed laser deposition. Ce doping leads to an enhanced Curie temperature near 150 K, close to that seen for oxygen-deficient EuO{sub 1-x}. However, the magnetization of Ce-doped EuO exhibits differences from that observed for Gd-doped and oxygen-deficient samples. The high-resolution angular-resolved photoemission from Ce-doped EuO reveals filling of conduction-band states near the X point. This indicates that the band gap in EuO is indirect, and that at 2% doping Ce-doped EuO{sub 1-x} is at least semimetallic.

Liu Pan; Tang Jinke [Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071 (United States); Colon Santana, Juan A.; Belashchenko, Kirill D.; Dowben, Peter A. [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299 (United States)

2011-04-01T23:59:59.000Z

140

Process for fabricating doped zinc oxide microsphere gel  

DOE Patents (OSTI)

Disclosed are a new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

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

1991-11-05T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Hydrogen Storage on Metal-Doped Ordered Mesoporous Carbons  

E-Print Network (OSTI)

Hydrogen Storage on Metal-Doped Ordered Mesoporous Carbons Shuguang Deng New Mexico State Meeting, May 18, 2010 #12;Outline · Research group · Hydrogen storage: background and status · Synthesis Adsorption in Ordered Mesoporous Carbon through Clathrate Formation" Int. J. Hydrogen Energy, 34, 8583

Nishiguchi, Michele

142

High capacity nickel battery material doped with alkali metal cations  

SciTech Connect

A high capacity battery material is made, consisting essentially of hydrated Ni(II) hydroxide, and about 5 wt. % to about 40 wt. % of Ni(IV) hydrated oxide interlayer doped with alkali metal cations selected from potassium, sodium and lithium cations.

Jackovitz, John F. (Monroeville, PA); Pantier, Earl A. (Penn Hills, PA)

1982-05-18T23:59:59.000Z

143

Suppression of the spin pumping in Pd/Ni{sub 81}Fe{sub 19} bilayers with nano-oxide layer  

SciTech Connect

We demonstrate that the spin pumping effect can be effectively suppressed with a nano-oxide layer. Spin pumping effect manifests itself by an enhancement of the Gilbert damping parameter in normal metal/ferromagnetic hetero-structures, while many spintronics devices prefer smaller damping parameter. Since the spin pumping effect is directly related with the spin dependent interface conductance, we can modify the spin pumping by altering the interface conductance with the nano-oxide layer. We prepared series of Pd/Ni{sub 81}Fe{sub 19} bilayers with different pausing time between Pd and Ni{sub 81}Fe{sub 19} depositions in order to control the interface conductance. The Gilbert damping parameters are determined from the line-width measurements in the ferromagnetic resonance spectra for each pausing time sample. They are 0.0490, 0.0296, 0.0278, and 0.0251 for 0, 6, 30, and 60 s pausing time, respectively. We find that the damping parameter of Pd/Ni{sub 81}Fe{sub 19} is almost recovered to one of the Cu/Ni{sub 81}Fe{sub 19} bilayer with 60 s pausing time, while the static magnetic properties are not noticeably changed.

Kim, Duck-Ho; Kim, Hong-Hyoun; You, Chun-Yeol [Department of Physics, Inha University, Namgu Incheon 402-751 (Korea, Republic of)

2011-08-15T23:59:59.000Z

144

Process for fabricating device structures for real-time process control of silicon doping  

DOE Patents (OSTI)

Silicon device structures designed to allow measurement of important doping process parameters immediately after the doping step has occurred. The test structures are processed through contact formation using standard semiconductor fabrication techniques. After the contacts have been formed, the structures are covered by an oxide layer and an aluminum layer. The aluminum layer is then patterned to expose the contact pads and selected regions of the silicon to be doped. Doping is then performed, and the whole structure is annealed with a pulsed excimer laser. But laser annealing, unlike standard annealing techniques, does not effect the aluminum contacts because the laser light is reflected by the aluminum. Once the annealing process is complete, the structures can be probed, using standard techniques, to ascertain data about the doping step. Analysis of the data can be used to determine probable yield reductions due to improper execution of the doping step and thus provide real-time feedback during integrated circuit fabrication.

Weiner, Kurt H. (San Jose, CA)

2001-01-01T23:59:59.000Z

145

High gain photoconductive semiconductor switch having tailored doping profile zones  

SciTech Connect

A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions into the substrate, then conducting epitaxial regrowth in the depressions with material of the desired doping profile. They may be formed by surface epitaxy. They may also be formed by deep diffusion processes. The zones act to reduce the energy density at the contacts by suppressing collective impact ionization and formation of filaments near the contact and by reducing current intensity at the contact through enhanced current spreading within the zones.

Baca, Albert G. (Albuquerque, NM); Loubriel, Guillermo M. (Albuquerque, NM); Mar, Alan (Albuquerque, NM); Zutavern, Fred J (Albuquerque, NM); Hjalmarson, Harold P. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM); Zipperian, Thomas E. (Edgewood, NM); O' Malley, Martin W. (Edgewood, NM); Helgeson, Wesley D. (Albuquerque, NM); Denison, Gary J. (Sandia Park, NM); Brown, Darwin J. (Albuquerque, NM); Sullivan, Charles T. (Albuquerque, NM); Hou, Hong Q. (Albuquerque, NM)

2001-01-01T23:59:59.000Z

146

Ytterbium-doped borate fluoride laser crystals and lasers  

DOE Patents (OSTI)

A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM'(BO.sub.3)F, where M, M' are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO.sub.3 F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator.

Schaffers, Kathleen I. (Pleasanton, CA); DeLoach, Laura D. (Manteca, CA); Payne, Stephen A. (Castro Valley, CA); Keszler, Douglas A. (Corvallis, OK)

1997-01-01T23:59:59.000Z

147

Imaging doped silicon test structures using low energy electron microscopy.  

SciTech Connect

This document is the final SAND Report for the LDRD Project 105877 - 'Novel Diagnostic for Advanced Measurements of Semiconductor Devices Exposed to Adverse Environments' - funded through the Nanoscience to Microsystems investment area. Along with the continuous decrease in the feature size of semiconductor device structures comes a growing need for inspection tools with high spatial resolution and high sample throughput. Ideally, such tools should be able to characterize both the surface morphology and local conductivity associated with the structures. The imaging capabilities and wide availability of scanning electron microscopes (SEMs) make them an obvious choice for imaging device structures. Dopant contrast from pn junctions using secondary electrons in the SEM was first reported in 1967 and more recently starting in the mid-1990s. However, the serial acquisition process associated with scanning techniques places limits on the sample throughput. Significantly improved throughput is possible with the use of a parallel imaging scheme such as that found in photoelectron emission microscopy (PEEM) and low energy electron microscopy (LEEM). The application of PEEM and LEEM to device structures relies on contrast mechanisms that distinguish differences in dopant type and concentration. Interestingly, one of the first applications of PEEM was a study of the doping of semiconductors, which showed that the PEEM contrast was very sensitive to the doping level and that dopant concentrations as low as 10{sup 16} cm{sup -3} could be detected. More recent PEEM investigations of Schottky contacts were reported in the late 1990s by Giesen et al., followed by a series of papers in the early 2000s addressing doping contrast in PEEM by Ballarotto and co-workers and Frank and co-workers. In contrast to PEEM, comparatively little has been done to identify contrast mechanisms and assess the capabilities of LEEM for imaging semiconductor device strictures. The one exception is the work of Mankos et al., who evaluated the impact of high-throughput requirements on the LEEM designs and demonstrated new applications of imaging modes with a tilted electron beam. To assess its potential as a semiconductor device imaging tool and to identify contrast mechanisms, we used LEEM to investigate doped Si test structures. In section 2, Imaging Oxide-Covered Doped Si Structures Using LEEM, we show that the LEEM technique is able to provide reasonably high contrast images across lateral pn junctions. The observed contrast is attributed to a work function difference ({Delta}{phi}) between the p- and n-type regions. However, because the doped regions were buried under a thermal oxide ({approx}3.5 nm thick), e-beam charging during imaging prevented quantitative measurements of {Delta}{phi}. As part of this project, we also investigated a series of similar test structures in which the thermal oxide was removed by a chemical etch. With the oxide removed, we obtained intensity-versus-voltage (I-V) curves through the transition from mirror to LEEM mode and determined the relative positions of the vacuum cutoffs for the differently doped regions. Although the details are not discussed in this report, the relative position in voltage of the vacuum cutoffs are a direct measure of the work function difference ({Delta}{phi}) between the p- and n-doped regions.

Nakakura, Craig Yoshimi; Anderson, Meredith Lynn; Kellogg, Gary Lee

2010-01-01T23:59:59.000Z

148

Method of fabricating optical waveguides by ion implantation doping  

DOE Patents (OSTI)

A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO/sub 3/ crystals are implanted with high concentrations of Ti dopant at ion energies of about 360 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000/degree/C produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguiding properties.

Appleton, B.R.; Ashley, P.R.; Buchal, C.J.

1987-03-24T23:59:59.000Z

149

OPTICAL AND DYNAMIC PROPERTIES OF UNDOPED AND DOPED SEMICONDUCTOR NANOSTRUCTURES  

Science Conference Proceedings (OSTI)

This chapter provides an overview of some recent research activities on the study of optical and dynamic properties of semiconductor nanomaterials. The emphasis is on unique aspects of these properties in nanostructures as compared to bulk materials. Linear, including absorption and luminescence, and nonlinear optical as well as dynamic properties of semiconductor nanoparticles are discussed with focus on their dependence on particle size, shape, and surface characteristics. Both doped and undoped semiconductor nanomaterials are highlighted and contrasted to illustrate the use of doping to effectively alter and probe nanomaterial properties. Some emerging applications of optical nanomaterials are discussed towards the end of the chapter, including solar energy conversion, optical sensing of chemicals and biochemicals, solid state lighting, photocatalysis, and photoelectrochemistry.

Grant, C D; Zhang, J Z

2007-09-28T23:59:59.000Z

150

Method for measuring the drift mobility in doped semiconductors  

DOE Patents (OSTI)

A method for measuring the drift mobility of majority carriers in semiconductors consists of measuring the current transient in a Schottky-barrier device following the termination of a forward bias pulse. An example is given using an amorphous silicon hydrogenated material doped with 0.2% phosphorous. The method is particularly useful with material in which the dielectric relaxation time is shorter than the carrier transit time. It is particularly useful in material useful in solar cells.

Crandall, Richard S. (Princeton, NJ)

1982-01-01T23:59:59.000Z

151

Enhancement In Charge Carrier Mobility Under Transition To Heavy Doping  

SciTech Connect

New experimental data confirming our suggestion about the universal character of critical phenomena accompanying the transition from 'an impurity gas' to 'an impurity condensate' with impurity concentration increasing are presented. The existence of the range of anomalous growth in the charge carrier mobility under transition to heavy doping is established for PbTe-PbSe solid solutions. The experimental results are analyzed on the basis of percolation theory taking into account alloy scattering and spatial correlations of impurity centers.

Rogacheva, E. I.; Nashchekina, O. N.; Vodorez, O. S. [National technical university 'Kharkov polytechnic institute', 21 Frunze St., Kharkov, 61002 (Ukraine)

2010-01-04T23:59:59.000Z

152

Method for measuring the drift mobility in doped semiconductors  

DOE Patents (OSTI)

A method for measuring the drift mobility of majority carriers in semiconductors consists of measuring the current transient in a Schottky-barrier device following the termination of a forward bias pulse. An example is given using an amorphous silicon hydrogenated material doped with 0.2% phosphorus. The method is particularly useful with material in which the dielectric relaxation time is shorter than the carrier transit time. It is particularly useful in material useful in solar cells. 10 figs.

Crandall, R.S.

1982-03-09T23:59:59.000Z

153

Non-aqueous solution preparation of doped and undoped lixmnyoz  

DOE Patents (OSTI)

A method for generation of phase-pure doped and undoped Li.sub.x Mn.sub.y O.sub.z precursors. The method of this invention uses organic solutions instead of aqueous solutions or nonsolution ball milling of dry powders to produce phase-pure precursors. These precursors can be used as cathodes for lithium-polymer electrolyte batteries. Dopants may be homogeneously incorporated to alter the characteristics of the powder.

Boyle, Timothy J. (5801 Eubank, N.E., Apt. #97, Albuquerque, NM 87111); Voigt, James A. (187 Aaramar La., Corrales, NM 87048)

1997-01-01T23:59:59.000Z

154

Synthesis of mesoporous NiO doped TiO{sub 2} submicrosphere via spray hydrolysis  

Science Conference Proceedings (OSTI)

NiO doped TiO{sub 2} submicrosphere have been prepared via spray hydrolysis. The doping concentration has been varied form 2 wt% to 15 wt%. Morphology of the submicrospheres has been investigated using small-angle neutron scattering and scanning electron microscopy. Elemental analysis has been carried out by energy dispersive X-ray analysis which confirms the doping concentrations. The mesopores in submicrospheres possess cylindrical morphology.

Bahadur, J.; Sen, D.; Prakash, J.; Singh, Ripandeep; Paul, B.; Mazumder, S.; Sathiyamoorthy, D. [Solid State Physics Division Bhabha Atomic Research Centre, Mumbai, 400085, India (India); Powder Metallurgy Division Bhabha Atomic Research Centre, Mumbai, 400085 (India); Solid State Physics, Division Bhabha Atomic Research Centre, Mumbai, 400085 (India); Materials Processing Division Bhabha Atomic Research Centre, Mumbai, 400085 (India); Solid State Physics Division Bhabha Atomic Research Centre, Mumbai, 400085 (India); Powder Metallurgy Division Bhabha Atomic Research Centre, Mumbai, 400085 (India)

2012-06-05T23:59:59.000Z

155

Global phase diagram of a doped Kitaev-Heisenberg model  

SciTech Connect

The global phase diagram of a doped Kitaev-Heisenberg model is studied using an $SU(2)$ slave-boson mean-field method. Near the Kitaev limit, $p$-wave superconducting states which break the time-reversal symmetry are stabilized as reported by You {\\it et al.} [Phys. Rev. B {\\bf 86}, 085145 (2012)] irrespective of the sign of the Kitaev interaction. By further doping, a $d$-wave superconducting state appears when the Kitaev interaction is antiferromagnetic, while another $p$-wave superconducting state appears when the Kitaev interaction is ferromagnetic. This $p$-wave superconducting state does not break the time-reversal symmetry as reported by Hyart {\\it et al.} [Phys. Rev. B {\\bf 85}, 140510 (2012)], and such a superconducting state also appears when the antiferromagnetic Kitaev interaction and the ferromagnetic Heisenberg interaction compete. This work, thus, demonstrates the clear difference between the antiferromagnetic Kitaev model and the ferromagnetic Kitaev model when carriers are doped while these models are equivalent in the undoped limit, and how novel superconducting states emerge when the Kitaev interaction and the Heisenberg interaction compete.

Okamoto, Satoshi [ORNL

2013-01-01T23:59:59.000Z

156

Altering the equilibrium condition in Sr-doped lanthanum manganite.  

DOE Green Energy (OSTI)

The material of choice for a solid oxide fuel cell cathode based on a yttria-stabilized zirconia (YSZ) electrolyte is doped lanthanum manganite, (La, Sr)MnO{sub 3}. It excels at many of the attributes necessary for a system to work at the required operating temperature and is flexible enough to allow for materials optimization. Although strontium-doping increases the electronic conductivity of the material, the ionic conductivity of the material remains negligible under operating conditions. Studies have shown that the internal equilibrium of the material heavily favors oxidation of the manganese and rather than the loss of lattice oxygen as a charge compensation mechanism. This lack of oxygen vacancies in the structure retards the ability of the material to conduct oxygen ions; thus the optimized system requires a large number of engineered triple point boundary locations to work efficiently. We have successfully doped the host LSM lattice to alter the interred equilibrium of the material to increase its ionic conductivity and thus lower the cathodic overpotential of the system. Our presentation will discuss these new materials, the results of cell tests, and a number of characterization experiments performed.

Carter, J. D.; Krumpelt, M.; Vaughey, J.; Wang, X.

1999-05-28T23:59:59.000Z

157

Nitrogen-Doped Graphitic Nanoribbons: Synthesis, Characterization and Transport  

SciTech Connect

Nitrogen-doped graphitic nanoribbons (Nx-GNRs), synthesized by chemical vapor deposition (CVD) using pyrazine as a nitrogen precursor, are reported for the first time. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) reveal that the synthesized materials are formed by multi-layered corrugated graphitic nanoribbons (GNRs) which in most cases exhibit the formation of curved graphene edges (loops). This suggests that during growth, nitrogen atoms promote loop formation; undoped GNRs do not form loops at their edges. Transport measurements on individual pure carbon GNRs exhibit a linear I-V (current-voltage) behavior, whereas Nx-GNRs show reduced current responses following a semiconducting-like behavior, which becomes more prominent for high nitrogen concentrations. To better understand the experimental findings, electron density of states (DOS), quantum conductance for nitrogen doped zigzag and armchair single-layer GNRs are calculated for different N doping concentrations using Density Functional Theory (DFT) and non-equilibrium Green functions. These calculations confirm the crucial role of nitrogen atoms in the transport properties, confirming that the nonlinear I-V curves are due to the presence of nitrogen atoms within the Nx-GNRs lattice that act as scattering sites. These characteristic Nx-GNRs transport could be advantageous in the fabrication of electronic devices including sensors in which metal-like undoped GNRs are unsuitable.

Jia, Xiaoting [Massachusetts Institute of Technology (MIT); Dresselhaus, M [Massachusetts Institute of Technology (MIT); Cruz Silva, Eduardo [ORNL; Munoz-Sandoval, E [Instituto de Microelectronica de Madrid (CNM, CSIC); Sumpter, Bobby G [ORNL; Terrones Maldonado, Humberto [ORNL; Terrones Maldonado, Humberto [ORNL; Lopez, Florentino [IPICyT

2013-01-01T23:59:59.000Z

158

Clarification of enhanced ferromagnetism in Be-codoped InMnP fabricated using Mn/InP:Be bilayers grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

The p-type InMnP:Be epilayers were prepared by the sequential growth of Mn/InP:Be bilayers using molecular-beam-epitaxy and the subsequent in-situ annealing at 200-300 deg. C. In triple-axis x-ray diffraction patterns, the samples revealed a shoulder peak indicative of intrinsic InMnP. The ferromagnetic transition in InMnP:Be was observed to occur at the elevated temperature of {approx}140 K, and the ferromagnetic spin-domains clearly appeared in magnetic force microscopy images. The improved ferromagnetic properties are attributed to the increased p-d hybridation due to high p-type conductivity of InMnP:Be (p {approx} 10{sup 20 }cm{sup -3}). The results suggest that enhanced ferromagnetism can be effectively obtained from Be-codoped InMnP.

Shon, Yoon; Lee, Sejoon; Taek Yoon, Im; Jeon, H. C.; Lee, D. J.; Kang, T. W. [Quantum-functional Semiconductor Research Center, Dongguk University-Seoul, Seoul 100-715 (Korea, Republic of); Song, J. D. [Center for Spintronics Research, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Yoon, Chong S. [Department of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, D. Y. [Department of Semiconductor Science, Dongguk University-Seoul, Seoul 100-715 (Korea, Republic of); Park, C. S. [School of Electrical Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of)

2011-11-07T23:59:59.000Z

159

Doping of germanium and silicon crystals with non-hydrogenic acceptors for far infrared lasers  

DOE Patents (OSTI)

A method for doping semiconductors used for far infrared lasers with non-hydrogenic acceptors having binding energies larger than the energy of the laser photons. Doping of germanium or silicon crystals with beryllium, zinc or copper. A far infrared laser comprising germanium crystals doped with double or triple acceptor dopants permitting the doped laser to be tuned continuously from 1 to 4 terahertz and to operate in continuous mode. A method for operating semiconductor hole population inversion lasers with a closed cycle refrigerator.

Haller, Eugene E. (Berkeley, CA); Brundermann, Erik (Berlin, DE)

2000-01-01T23:59:59.000Z

160

Bismuth-doped optical fibres: A new breakthrough in near-IR lasing media  

SciTech Connect

Recent results demonstrate that bismuth-doped optical fibres have considerable potential as near-IR active lasing media. This paper examines bismuth-doped fibres intended for the fabrication of fibre lasers and optical amplifiers and reviews recent results on the luminescence properties of various types of bismuth-doped fibres and the performance of bismuth-doped fibre lasers and optical amplifiers for the spectral range 1150 - 1550 nm. Problems are discussed that have yet to be solved in order to improve the efficiency of the bismuth lasers and optical amplifiers. (optical fibres, lasers and amplifiers. properties and applications)

Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2012-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Highly Transparent and Conducting ALD of Doped ZnO Thin Films ...  

Science Conference Proceedings (OSTI)

... and Conducting ALD of Doped ZnO Thin Films for TCO Applications · Hybrid Aerogel/Nanorod Functional Materials for Energy and Sensing Applications.

162

Synthesis and characterization of chloride doped polyaniline by bulk oxidative chemical polymerization.Doping effect on electrical conductivity  

E-Print Network (OSTI)

Conductive polymers or "organic metals" are highly engineered nanostructured materials made from organic building blocks. They are candidates as molecular wires for nanotechnology applications in molecular electronics. The conduction in these polymers is due to the presence of delocalized molecular orbitals. In this work, we present the synthesis of chloride doped polyaniline by bulk oxidative chemical polymerization using a solid aniline salt as a monomer instead of liquid aniline to diminish toxic hazards. The FTIR and UV-visible spectra confirmed the expected structure of the polymer. The electrical conductivity measured using a four-probe method was 1.7 S/cm. The dependence of impedance modulus on frequency was measured using an HP impedance analyzer in the range 10 kHz-13 MHz. The influence of doping and the preparation temperature on the electrical conductivity were also investigated.

Yomen Atassi; Mohammad Tally; Mazen Ismail

2008-09-21T23:59:59.000Z

163

The Electric and Optical Properties of Doped Small Molecular Organic Light-Emitting Devices  

SciTech Connect

Organic light-emitting devices (OLEDs) constitute a new and exciting emissive display technology. In general, the basic OLED structure consists of a stack of fluorescent organic layers sandwiched between a transparent conducting-anode and metallic cathode. When an appropriate bias is applied to the device, holes are injected from the anode and electrons from the cathode; some of the recombination events between the holes and electrons result in electroluminescence (EL). Until now, most of the efforts in developing OLEDs have focused on display applications, hence on devices within the visible range. However some organic devices have been developed for ultraviolet or infrared emission. Various aspects of the device physics of doped small molecular OLEDs were described and discussed. The doping layer thickness and concentration were varied systematically to study their effects on device performances, energy transfer, and turn-off dynamics. Low-energy-gap DCM2 guest molecules, in either {alpha}-NPD or DPVBi host layers, are optically efficient fluorophores but also generate deep carrier trap-sites. Since their traps reduce the carrier mobility, the current density decreases with increased doping concentration. At the same time, due to efficient energy transfer, the quantum efficiency of the devices is improved by light doping or thin doping thickness, in comparison with the undoped neat devices. However, heavy doping induces concentration quenching effects. Thus, the doping concentration and doping thickness may be optimized for best performance.

Kwang-Ohk Cheon

2003-08-05T23:59:59.000Z

164

Expansion on reduction of calcium doped lanthanum chromite  

DOE Green Energy (OSTI)

Doped lanthanum chromites have been considered as interconnect materials for the solid oxide fuel cell (SOFC) because of their favorable chemical and electrical properties under both oxidizing and reducing environments. Several investigators have studied the materials properties of the doped lanthanum chromites to optimize their overall performance as an interconnect material. These properties include electrical conductivity, thermal expansion, sinterability, and chemical compatibility with other cell components. These properties are optimized by the amount of dopants substituted into chromite which are usually Ca or Sr. Figure 1 shows the range of values for these properties. Another important characteristic becoming more of a concern as investigators are building SOFC stacks is that doped lanthanum chromite expands when reduced in a low oxygen partial pressure (pO{sub 2}) (<10{sup -12} atm). Plates used to separate oxidizing and fuel gases can deform because of the pO{sub 2} gradient across the interconnect material. This presentation is a summary of work which will be presented at the Fourth International Symposium on Solid Oxide Fuel Cells. In this article, the possible causes of expansion on reduction of the interconnect will be discussed by using a two-dimensional crystal model. The biaxial strain of the stack is calculated under the assumption that the cell components are forced to remain planar. From this, the maximum stress buildup in the interconnect and electrolyte is estimated. In addition, the effects of thermal expansion mismatch and expansion on reduction of the interconnect are compared, and the optimum interconnect composition from a mechanical standpoint is reported.

Carter, J.D.; Hendriksen, P.V.; Mogensen, M. [Riso National Lab., Roskilde (Denmark). Materials Dept.

1995-07-01T23:59:59.000Z

165

Electronic and Magnetic Properties of Metal-Doped BN Sheet: A First-Principles Study  

SciTech Connect

Electronic and magnetic properties of BN sheet doped with 3d transition metals (Fe, Co and Ni) have been investigated using ab initio calculations. Our calculations show many interesting physical properties in metal-doped BN sheet. Fe-doped BN sheet is a half-metal with the magnetic moment of 2.0 ?B, and Co-doped BN sheet becomes a narrow-gap semiconductor with the magnetic moment of 1.0 ?B. However, no magnetic moment is induced on Ni-doped BN sheet, which has the same band gap as pristine BN sheet. Furthermore, Fe atom is easy to form isolated particle on BN sheet, while Ni and Co atoms are likely to form sheet-supported metal nanotemplate. These results are useful for spintronics application and could help in the development of magnetic nanotructures and metallic nanotemplate at room temperature.

Zhou, Yungang; Xiao-Dong, J.; Wang, Zhiguo; Xiao, Haiyan Y.; Gao, Fei; Zu, Xiaotao T.

2010-07-21T23:59:59.000Z

166

Investigation of structure, magnetic, and transport properties of Mn-doped SiC films  

SciTech Connect

Mn-doped SiC films were fabricated by radio frequency magnetron sputtering technique. The structure, composition, and magnetic and transport properties of the films were investigated. The results show the films have the 3C-SiC crystal structure and the doped Mn atoms in the form of Mn{sup 2+} ions substitute for C sites in SiC lattice. All the films are ferromagnetic at 300 K, and the ferromagnetism in films arises from the doped Mn atoms and some extended defects. In addition, the saturation magnetization increases with the Mn-doped concentration increasing. The Mn doping does not change the semiconductor characteristics of the SiC films.

Sun Xianke [School of Material Science and Engineering, Tianjin University, Tianjin 300172 (China); Tianjin Key Laboratory for Photoelectric Materials and Devices, Tianjin University of Technology, Tianjin 300384 (China); Guo Ruisong [School of Material Science and Engineering, Tianjin University, Tianjin 300172 (China); An Yukai [Tianjin Key Laboratory for Photoelectric Materials and Devices, Tianjin University of Technology, Tianjin 300384 (China); School of Material Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Liu Jiwen [School of Material Science and Engineering, Tianjin University, Tianjin 300172 (China); Tianjin Key Laboratory for Photoelectric Materials and Devices, Tianjin University of Technology, Tianjin 300384 (China); School of Material Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2013-07-15T23:59:59.000Z

167

Electrically conductive doped block copolymer of polyacetylene and polyisoprene  

SciTech Connect

An electrically conductive block copolymer of polyisoprene and polyacetyl and a method of making the same are disclosed. The polymer is prepared by first polymerizing isoprene with n-butyllithium in a toluene solution to form an active isoprenyllithium polymer. The active polymer is reacted with an equimolar amount of titanium butoxide and subsequently exposed to gaseous acetylene. A block copolymer of polyisoprene and polyacetylene is formed. The copolymer is soluble in common solvents and may be doped with I.sub.2 to give it an electrical conductivity in the metallic regime.

Aldissi, Mahmoud (Los Alamos, NM)

1985-01-01T23:59:59.000Z

168

Doped H(2)-Filled RF Cavities for Muon Beam Cooling  

DOE Green Energy (OSTI)

RF cavities pressurized with hydrogen gas may provide effective muon beam ionization cooling needed for muon colliders. Recent 805 MHz test cell studies reported below include the first use of SF{sub 6} dopant to reduce the effects of the electrons that will be produced by the ionization cooling process in hydrogen or helium. Measurements of maximum gradient in the Paschen region are compared to a simulation model for a 0.01% SF{sub 6} doping of hydrogen. The observed good agreement of the model with the measurements is a prerequisite to the investigation of other dopants.

Yonehara, K.; Chung, M.; Jansson, A.; Hu, M.; Moretti, A.; Popovic, M.; /Fermilab; Alsharo'a, M.; Johnson, R.P.; Neubauer, M.; Sah, R.; /Muons Inc., Batavia; Rose, D.V.; /Voss Sci., Albuquerque

2009-05-01T23:59:59.000Z

169

Variable temperature electrochemical strain microscopy of Sm-doped ceria  

Science Conference Proceedings (OSTI)

Variable temperature electrochemical strain microscopy has been used to study the electrochemical activity of Sm-doped ceria as a function of temperature and bias. The electrochemical strain microscopy hysteresis loops have been collected across the surface at different temperatures and the relative activity at different temperatures has been compared. The relaxation behavior of the signal at different temperatures has been also evaluated to relate kinetic process during bias induced electrochemical reactions with temperature and two different kinetic regimes have been identified. The strongly non-monotonic dependence of relaxation behavior on temperature is interpreted as evidence for water-mediated mechanisms.

Jesse, Stephen [ORNL; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Kalinin, Sergei V [ORNL; Eliseev, E. A. [National Academy of Science of Ukraine, Kiev, Ukraine; Yang, Nan [ORNL; Doria, Sandra [ORNL; Tebano, Antonello [ORNL

2013-01-01T23:59:59.000Z

170

Nitrogen-doped Graphene and Its Electrochemical Applications  

SciTech Connect

Nitrogen-doped graphene (N-graphene) is obtained by exposing graphene to nitrogen plasma. N-graphene exhibits much higher electrocatalytic activity toward oxygen reduction and H2O2 reduction than graphene, and much higher durability and selectivity than the widely-used expensive Pt. The excellent electrochemical performance of N-graphene is attributed to nitrogen functional groups and the specific properties of graphene. This indicates that N-graphene is promising for applications in electrochemical energy devices (fuel cells, metal-air batteries) and biosensors.

Shao, Yuyan; Zhang, Sheng; Engelhard, Mark H.; Li, Guosheng; Shao, Guocheng; Wang, Yong; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

2010-06-04T23:59:59.000Z

171

Depression of the superconducting critical temperature and finite-size scaling relation in YBa2Cu3O7-?/La2/3Ca1/3MnO3 bilayers  

Science Conference Proceedings (OSTI)

High-quality YBa2Cu3O7-?/La2/3Ca 1/3MnO3 (YBCO/LCMO) bilayers were fabricated on (001)-oriented SrTiO3 (STO) substrates by dc-sputtering technique. Bottom layer was ... Keywords: 74.45.+c, 74.62.-c, 74.72.-h, 74.78.Fk, 75.47.Lx, 75.70.-i, Cuprate superconductors, Manganites, Superconductor/ferromagnet proximity effect

O. Morán; E. Baca; F. A. Pérez

2008-03-01T23:59:59.000Z

172

Crystallization and doping of amorphous silicon on low temperature plastic  

DOE Patents (OSTI)

A method or process of crystallizing and doping amorphous silicon (a-Si) on a low-temperature plastic substrate using a short pulsed high energy source in a selected environment, without heat propagation and build-up in the substrate is disclosed. The pulsed energy processing of the a-Si in a selected environment, such as BF3 and PF5, will form a doped micro-crystalline or poly-crystalline silicon (pc-Si) region or junction point with improved mobilities, lifetimes and drift and diffusion lengths and with reduced resistivity. The advantage of this method or process is that it provides for high energy materials processing on low cost, low temperature, transparent plastic substrates. Using pulsed laser processing a high (>900 C), localized processing temperature can be achieved in thin films, with little accompanying temperature rise in the substrate, since substrate temperatures do not exceed 180 C for more than a few microseconds. This method enables use of plastics incapable of withstanding sustained processing temperatures (higher than 180 C) but which are much lower cost, have high tolerance to ultraviolet light, have high strength and good transparency, compared to higher temperature plastics such as polyimide. 5 figs.

Kaschmitter, J.L.; Truher, J.B.; Weiner, K.H.; Sigmon, T.W.

1994-09-13T23:59:59.000Z

173

Crystallization and doping of amorphous silicon on low temperature plastic  

DOE Patents (OSTI)

A method or process of crystallizing and doping amorphous silicon (a-Si) on a low-temperature plastic substrate using a short pulsed high energy source in a selected environment, without heat propagation and build-up in the substrate. The pulsed energy processing of the a-Si in a selected environment, such as BF3 and PF5, will form a doped micro-crystalline or poly-crystalline silicon (pc-Si) region or junction point with improved mobilities, lifetimes and drift and diffusion lengths and with reduced resistivity. The advantage of this method or process is that it provides for high energy materials processing on low cost, low temperature, transparent plastic substrates. Using pulsed laser processing a high (>900.degree. C.), localized processing temperature can be achieved in thin films, with little accompanying temperature rise in the substrate, since substrate temperatures do not exceed 180.degree. C. for more than a few microseconds. This method enables use of plastics incapable of withstanding sustained processing temperatures (higher than 180.degree. C.) but which are much lower cost, have high tolerance to ultraviolet light, have high strength and good transparency, compared to higher temperature plastics such as polyimide.

Kaschmitter, James L. (Pleasanton, CA); Truher, Joel B. (Palo Alto, CA); Weiner, Kurt H. (Campbell, CA); Sigmon, Thomas W. (Beaverton, OR)

1994-01-01T23:59:59.000Z

174

The influence of oscillating electromagnetic fields on membrane structure and function: Synthetic liposome and natural membrane bilayer systems with direct application to the controlled delivery of chemical agents  

Science Conference Proceedings (OSTI)

Investigations have been conducted to determine if an imposed electromagnetic field can influence membrane transport, and ion and drug permeability in both synthetic and natural cell membrane systems. Microwave fields enhance accumulation of sodium in the lymphocyte and induce protein shedding at Tc. Microwaves also trigger membrane permeability of liposome systems under specific field exposure conditions. Sensitivity varies in a defined way in bilayers displaying a membrane structural phase transition temperature, Tc; maximal release was observed at or near Tc. Significantly, liposome systems without a membrane phase transition were also found to experience permeability increases but, in contrast, this response was temperature independent. The above results indicate that field-enhanced drug release occurs in liposome vesicles that possess a Tc as well as non-Tc liposomes. Additional studies extend non-Tc liposome responses to the in vivo case in which microwaves trigger Gentamicin release from a liposome depot'' placed subcutaneously in the rat hind leg. In addition, evidence is provided that cell surface sequestered liposomes can be triggered by microwave fields to release drugs directly into target cells. 24 refs., 6 figs.

Liburdy, R.P.; de Manincor, D.; Fingado, B.

1989-09-01T23:59:59.000Z

175

Thermophotovoltaic energy conversion system having a heavily doped n-type region  

DOE Patents (OSTI)

A thermophotovoltaic (TPV) energy conversion semiconductor device is provided which incorporates a heavily doped n-type region and which, as a consequence, has improved TPV conversion efficiency. The thermophotovoltaic energy conversion device includes an emitter layer having first and second opposed sides and a base layer in contact with the first side of the emitter layer. A highly doped n-type cap layer is formed on the second side of the emitter layer or, in another embodiment, a heavily doped n-type emitter layer takes the place of the cap layer.

DePoy, David M. (Clifton Park, NY); Charache, Greg W. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY)

2000-01-01T23:59:59.000Z

176

Generation of high peak power pulse using 2 stage erbium-doped fiber amplifier  

E-Print Network (OSTI)

This thesis presents the results obtained from generation of high repetition rate, high power output pulse using an erbium-doped fiber amplifier (EDFA). Two stage amplification was employed. The first stage setup used 980nm pump laser to pump erbium-doped fiber. For the second stage, two 1480nm pump lasers were used to pump erbium-doped fiber in both forward and backward propagating direction. The signal laser was modulated to produce pulses with high repetition rate high peak power. The first stage produced pulse peak power of 2.52W. The overall output peak power, which is produced by the first and second stage, is 16W.

Lee, Kyung-Woo

2000-01-01T23:59:59.000Z

177

Resonant absorption of a short-pulse laser in a doped dielectric  

SciTech Connect

A simple model is used to calculate the energy absorption efficiency when a laser of short pulse length impinges on a dielectric slab that is doped with an impurity with a resonant line at the laser frequency. It is found that the energy absorption efficiency is maximized for a certain degree of doping concentration (at a given pulse length) and also for a certain pulselength (at a given doping concentration). Dimensionless parameters are constructed, allowing calculations with one set of parameters be used to infer the results expected for other sets of parameters. {copyright} {ital 1999 American Institute of Physics.}

Ang, L.K.; Lau, Y.Y.; Gilgenbach, R.M. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States)

1999-05-01T23:59:59.000Z

178

Enhancing the Electron Mobility via Delta-Doping in SrTiO3  

Science Conference Proceedings (OSTI)

We fabricated high-mobility {delta}-doped structures in SrTiO{sub 3} thin films in order to investigate the low temperature electronic transport properties of confined carriers in this system. An enhancement of the electron mobility above the bulk value was observed as the doped layer thickness decreased. High-field Hall measurements revealed that this mobility enhancement originates from higher-mobility electrons in the undoped clean regions, which have quantum-mechanically broadened from the doped layer. Because of the absence of apparent lattice misfit between the layers, this structure is highly suitable for investigating two-dimensional electron gases in SrTiO{sub 3}

Kozuka, Y.

2011-08-11T23:59:59.000Z

179

Lattice vibrations of pure and doped GaSe  

Science Conference Proceedings (OSTI)

The Bridgman method is used to grow especially undoped and doped single crystals of GaSe. Composition and impurity content of the grown crystals were determined using X-ray fluorescence (XRF) method. X-ray diffraction, Raman scattering, photoluminescence (PL), and IR transmission measurements were performed at room temperature. The long wavelength lattice vibrations of four modifications of GaSe were described in the framework of modified one-layer linear-chain model which also takes into consideration the interaction of the selenium (Se) atom with the second nearest neighbor gallium (Ga) atom in the same layer. The existence of an eight-layer modification of GaSe is suggested and the vibrational frequencies of this modification are explained in the framework of a lattice dynamical model considered in the present work. Frequencies and the type of vibrations (gap, local, or resonance) for the impurity atoms were calculated and compared with the experimental results.

Allakhverdiev, K. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey) and Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan)]. E-mail: kerim.allahverdi@mam.gov.tr; Baykara, T. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Ellialtioglu, S. [Department of Physics, Middle East Technical University, Ankara 06531 (Turkey); Hashimzade, F. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Huseinova, D. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Kawamura, K. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan); Kaya, A.A. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Kulibekov, A.M. [Department of Physics, Mugla University, Mugla 48000 (Turkey); Onari, S. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan)

2006-04-13T23:59:59.000Z

180

Cr/sup 3 +/-doped colquiriite solid state laser material  

DOE Patents (OSTI)

Chromium doped colquiriite, LiCaAlF/sub 6/:Cr/sup 3 +/, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr/sup 3 +/ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slope efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd/sup 3 +/ or Tm/sup 3 +/ for use in a multimegajoule single shot fusion research facility. 4 figs.

Payne, S.A.; Chase, L.L.; Newkirk, H.W.; Krupke, W.F.

1988-03-31T23:59:59.000Z

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181

Welding and Weldability of Thorium-Doped Iridium Alloys  

SciTech Connect

Ir-0.3%W alloys doped with thorium are currently used as post-impact containment material for radioactive fuel in thermoelectric generators that provide stable electrical power for a variety of outer planetary space exploration missions. Welding and weldability of a series of alloys was investigated using arc and laser welding processes. Some of these alloys are prone to severe hot-cracking during welding. Weldability of these alloys was characterized using Sigmajig weldability test. Hot-cracking is influenced to a great extent by the fusion zone microstructure and composition. Thorium content and welding atmosphere were found to be very critical. The weld cracking behavior in these alloys can be controlled by modifying the fusion zone microstructure. Fusion zone microstructure was found to be controlled by welding process, process parameters, and the weld pool shape.

David, S.A.; Ohriner, E.K.; King, J.F.

2000-03-12T23:59:59.000Z

182

Highly Conductive Textured Molybdenum Doped Indium Oxide Thin Films  

DOE Green Energy (OSTI)

We report on the pulsed laser deposition (PLD) of Mo-doped indium oxide (IMO) films with mobilities of up to 125 cm2/Vsec. Films have been grown from targets with 1-4 wt.% molybdenum. The optimum electrical and optical properties were obtained with the 2% target and yielded a maximum conductivity of 3717 S/cm with mobilities of 99 cm2/V-sec on (100) yttria stabilized zirconia (YSZ) single crystal substrates. Films also exhibit greater than 90% transparency in the visible range. Compared to commercial indium tin oxide (ITO) films, these PLD-grown IMO films have similar conductivity but since they have substantially higher mobility they have a correspondingly lower carrier concentration. The lower carrier concentration should extend the infrared window of the transparency for films of the same conductivity. This may lead to improved performance in a number of applications requiring improved performance TCOs.

Warmsingh, C.; Yoshida, Y.; Readey, D.; Perkins, J.; Parilla, P.; Teplin, C.; Kaydanova, T.; Alleman, J.; Gedvilas, L.; Keyes, B.; Gessert, T.; Coutts, T.; Ginley, D.

2003-05-01T23:59:59.000Z

183

Cr.sup.3+ -doped colquiriite solid state laser material  

DOE Patents (OSTI)

Chromium doped colquiriite, LiCaAlF.sub.6 :Cr.sup.3+, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr.sup.3+ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slop efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd.sup.3+ or Tm.sup.3+ for use in a multimegajoule single shot fusion research facility.

Payne, Stephen A. (Castro Valley, CA); Chase, Lloyd L. (Livermore, CA); Newkirk, Herbert W. (Livermore, CA); Krupke, William F. (Pleasanton, CA)

1989-01-01T23:59:59.000Z

184

Pulsed energy synthesis and doping of silicon carbide  

DOE Patents (OSTI)

A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate is disclosed, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27--730 C is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including HETEROJUNCTION-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

Truher, J.B.; Kaschmitter, J.L.; Thompson, J.B.; Sigmon, T.W.

1995-06-20T23:59:59.000Z

185

Pulsed energy synthesis and doping of silicon carbide  

DOE Patents (OSTI)

A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27.degree.-730.degree. C. is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including hetero-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

Truher, Joel B. (San Rafael, CA); Kaschmitter, James L. (Pleasanton, CA); Thompson, Jesse B. (Brentwood, CA); Sigmon, Thomas W. (Beaverton, OR)

1995-01-01T23:59:59.000Z

186

Crystallizing hard-sphere glasses by doping with active particles  

E-Print Network (OSTI)

Crystallization and vitrification are two different routes to form a solid. Normally these two processes suppress each other, with the glass transition preventing crystallization at high density (or low temperature). This is even true for systems of colloidal hard spheres, which are commonly used as building blocks for fabricating photonic crystals [1-3]. Here, by performing Brownian dynamics simulations of glass systems consisting of mixtures of active and passive hard spheres, we show that the crystallization of such hard-sphere glasses can be dramatically promoted by doping the system with small amounts of active particles. Surprisingly, even hard-sphere glasses of packing fraction up to $\\phi = 0.635$ crystallize, which is around 0.5% below the random close packing ~ 0.64. Our results suggest a novel way of fabricating crystalline materials from (colloidal) glasses. This is particularly important for materials that get easily kinetically trapped in glassy states, and crystal nucleation hardly occurs.

Ran Ni; Martien A. Cohen Stuart; Marjolein Dijkstra; Peter G. Bolhuis

2013-10-28T23:59:59.000Z

187

Systematics of Pure and Doped He-4 Clusters  

E-Print Network (OSTI)

Optimized variational calculations have been carried out for pure and doped clusters of He-4 atoms up to a cluster size of N=1000 particles. For small cluster sizes with less than or equal to 112 particles, where comparisons with existing diffusion Monte Carlo results are possible, we find excellent agreement for the ground-state energy, correlation, and structure functions. For larger clusters, our ground-state energies extrapolate smoothly toward a bulk limit of -7.2 K with a surface energy of 0.272 K Angstrom(-2). The resulting ground-state densities show unmistakable oscillations, confirming our earlier conclusions based on diffusion Monte Carlo studies. The present study of large clusters allows us to bridge the gap between finite systems and the bulk limit. Specifically, we show how the bulk limit of collective energies is reached as well as how the bulk Feynman spectrum is reproduced in the S-wave component of the dynamic structure function in large droplets. By plotting the collective excitation energy of higher multiple modes as a function of an effective wave number K = root l(l+1)/R, we show that the resulting spectrum can be directly compared with experimental excitation energies determined for plane liquid surfaces and films. By summing up to l = 50 partial wave components, we show that the full dynamic structure function simultaneously displays the phonon-roton and the ripplon excitation spectrum. In the case of helium droplets doped with impurities such as rare gas atoms or the SF6 molecule, we show that the dipole collective mode becomes unstable with increased droplet size, strongly indicating that these impurities are delocalizled inside large droplets. The microscopic character of the instability is revealed in the excitation functions and transition densities of the dipole mode. The introduction of impurities also profoundly alters the dynamic structure function, severely ''fragments'' the Feynman spectrum, and obliterates landmark structures such as the maxon and the roton.

Chin, Siu A.; KROTSCHECK, E.

1995-01-01T23:59:59.000Z

188

Dielectric and electromechanical properties of barium and zirconium co-doped sodium bismuth titanate  

E-Print Network (OSTI)

Compositional exploration was conducted within the alkaline bismuth titanate system by doping on the A- and B- sites with Ba?² and Zr??, respectively. Results on the phase, dielectric and electromechanical properties of ...

Sheets, Sossity A. (Sossity Amber), 1973-

2000-01-01T23:59:59.000Z

189

Structural properties of fluorozirconate-based glass ceramics doped with multivalent europium  

SciTech Connect

The structure/property relationships of fluorochlorozirconate glass ceramics as a function of divalent and trivalent europium (Eu) co-doping and thermal processing have been investigated; the influence of doping ratio on the formation of barium chloride (BaCl2) nanocrystals therein was elucidated. X-ray absorption near-edge structure spectroscopy shows that the post-thermal annealing changes the Eu valence of the as-poured glass slightly, but during the melting process Eu3+ is more strongly reduced to Eu2+, in particular, when doped as a chloride instead of fluoride compound. The Eu2+-to-Eu3+ doping ratio also plays a significant role in chemical equilibrium in the melt. X-ray diffraction measurements indicate that a higher Eu2+ fraction leads to a BaCl2 phase transition from hexagonal to orthorhombic structure at a lower temperature.

PaBlick, C.; Müller, O.; Lützenkirchen-Hecht, D.; Frahm, R.; Johnson, J.A.; Schweizer, S. (U. Halle); (Bergische); (Tennessee-C)

2012-10-10T23:59:59.000Z

190

Chemical Expansion and Frozen-In Oxygen Vacancies in Pr-Doped Ceria  

E-Print Network (OSTI)

Doped CeO2 is a promising candidate for solid oxide fuel cell electrolyte and electrode applications because of its high ionic conductivity and reduction/oxidation behavior at intermediate temperatures. Its electronic and ...

Kuru, Yener

2011-01-01T23:59:59.000Z

191

Physical Insight Into Substitutional N-Doped Graphene Nanoribbons With Armchair Edges  

Science Conference Proceedings (OSTI)

Electronic structures of graphene nanoribbons with armchair edges (AGNRs) containing N-substitutional impurity have been investigated, using ab initio density functional theory. It is shown that the electronic structures of the doped AGNRs are different ...

Shan Sheng Yu; Wei Tao Zheng; Qing Jiang

2011-09-01T23:59:59.000Z

192

Adsorption sites of hydrogen atom on pure and Mg-doped multi-walled carbon nanotubes  

Science Conference Proceedings (OSTI)

Hydrogen adsorption sites on pure multiwalled carbon nanotube (MWCNT) and Mg-doped MWCNTs material system have been investigated using molecular dynamics (MD) simulations as well as quantum chemical calculations. Through combining MWCNTs with Mg, the ...

A. A. Al-Ghamdi, E. Shalaan, F. S. Al-Hazmi, Adel S. Faidah, S. Al-Heniti, M. Husain

2012-01-01T23:59:59.000Z

193

Thermoelectric performance of electron and hole doped PtSb2  

Science Conference Proceedings (OSTI)

We investigate the thermoelectric properties of electron and hole doped PtSb2. Our results show that for doping of 0.04 holes per unit cell (1:5 1020 cm 3) PtSb2 shows a high Seebeck coefficient at room temperature, which can also be achieved at other temperatures by controlling the carrier concentration (both electron and hole). The electrical conductivity becomes temperature independent when the doping exceeds some 0.2 electrons/holes per unit cell. The figure of merit at 800 K in electron and hole doped PtSb2 is comparatively low at 0.13 and 0.21, respectively, but may increase significantly with As alloying due to the likely opening of a band gap and reduction of the lattice thermal conductivity

Saeed, Yasir [King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia; Singh, Nirprenda [King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia; Schwingenschlogl, Udo [King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia; Parker, David S [ORNL

2013-01-01T23:59:59.000Z

194

Growth and Magnetic Properties of Mn-doped Germanium near the Kinetic Solubility Limit  

Science Conference Proceedings (OSTI)

Growth of high-quality dilute magnetic semiconductor (DMS) material is often compromised by the low solubility of magnetic dopants, leading to formation of precipitates. Here, we explore the feasibility of growing precipitate-free Mn-doped Ge at doping levels near the kinetic solubility limit. Ge:Mn DMS films were grown at low temperature so as to minimize precipitate formation. Meanwhile, epitaxial quality was maintained by employing a very low growth rate. The magnetic properties of these lightly doped films exhibit both interesting contrasts and similarities with those of heavily-doped DMS reported in the literature, indicating that the substitutional Mn contents are very similar. Films grown at 95 degree C are free of intermetallic precipitates, offering useful opportunities for studying the fundamentals of carrier mediated exchange and metal insulator transitions without complications arising from precipitate formation.

Ozer, Mustafa M [University of Tennessee, Knoxville (UTK); Thompson, James R [ORNL; Weitering, Harm H [ORNL

2012-01-01T23:59:59.000Z

195

Raman spectroscopy study of heat-treated and boron-doped double wall carbon nanotubes  

E-Print Network (OSTI)

We performed Raman spectroscopy experiments on undoped and boron-doped double walled carbon nanotubes (DWNTs) that exhibit the “coalescence inducing mode” as these DWNTs are heat treated to temperatures between 1200 °C ...

Villalpando Paez, Federico

196

Coaxially aligned polyaniline nanofibers doped with 3-thiopheneacetic acid through interfacial polymerization  

Science Conference Proceedings (OSTI)

Coaxially aligned polyaniline (PANI) nanofibers doped with 3-thiopheneacetic acid (TAA) were chemically synthesized by the interfacial polymerization of aniline in the presence of TAA, using iron (III) chloride hexahydrate (FeCl3?6H2O) ...

Lixia Zhang; Geoffrey I. N. Waterhouse; Lijuan Zhang

2011-01-01T23:59:59.000Z

197

Free volumes associated with sintering in gadolinium doped ceria solid solutions  

Science Conference Proceedings (OSTI)

Gadolinium-doped ceria (GDC) solid solution prepared by the oxalate coprecipitation method is investigated by X-ray diffraction (XRD), complex impedance analysis, and positron lifetime spectroscopy. XRD reveals an expansion of GDC lattice constant by ...

Tomomi Kosaka; Kiminori Sato

2010-01-01T23:59:59.000Z

198

Efficient multi?keV x?ray sources from Ti?doped aerogel targets  

Science Conference Proceedings (OSTI)

We have measured the production of hv ? 4.7 keV x?rays from low?density Ti?doped aerogel (? ? 3 mg/cc) targets at the OMEGA laser facility (University of Rochester)

K. B. Fournier; C. Constantin; G. Gregori; M. C. Miller; C. A. Back; L. J. Suter; J. Davis; J. Grun

2004-01-01T23:59:59.000Z

199

Engineering broadband and anisotropic photoluminescence emission from rare earth doped tellurite thin film photonic crystals  

E-Print Network (OSTI)

Broadband and anisotropic light emission from rare-earth doped tellurite thin films is demonstrated using Er[superscript 3+]-TeO[subscript 2] photonic crystals (PhCs). By adjusting the PhC parameters, photoluminescent light ...

Vanhoutte, Michiel

200

Electronic Properties of Nitrogen-/Boron-Doped Graphene Nanoribbons With Armchair Edges  

Science Conference Proceedings (OSTI)

Calculation of electronic structures has been performed for graphene nanoribbons with eight-armchair edges containing nitrogen or boron substitutional impurity by using ab initio density functional theory. It is found that the electronic structures ... Keywords: Doping, graphene, nanotechnology, nitrogen

Shan Sheng Yu; Wei Tao Zheng; Qing Jiang

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Understanding the viability of impurity-band photovoltaics : a case study of S-doped Si  

E-Print Network (OSTI)

This thesis explores the electronic structure, optical properties, and carrier lifetimes in silicon that is doped with sulfur beyond the equilibrium solid solubility limit, with a focus on applications as an absorber layer ...

Sullivan, Joseph Timothy, Ph. D. Massachusetts Institute of Technology

2013-01-01T23:59:59.000Z

202

Ultra High p-doping Material Research for GaN Based Light Emitters  

Science Conference Proceedings (OSTI)

The main goal of the Project is to investigate doping mechanisms in p-type GaN and AlGaN and controllably fabricate ultra high doped p-GaN materials and epitaxial structures. Highly doped p-type GaN-based materials with low electrical resistivity and abrupt doping profiles are of great importance for efficient light emitters for solid state lighting (SSL) applications. Cost-effective hydride vapor phase epitaxial (HVPE) technology was proposed to investigate and develop p-GaN materials for SSL. High p-type doping is required to improve (i) carrier injection efficiency in light emitting p-n junctions that will result in increasing of light emitting efficiency, (ii) current spreading in light emitting structures that will improve external quantum efficiency, and (iii) parameters of Ohmic contacts to reduce operating voltage and tolerate higher forward currents needed for the high output power operation of light emitters. Highly doped p-type GaN layers and AlGaN/GaN heterostructures with low electrical resistivity will lead to novel device and contact metallization designs for high-power high efficiency GaN-based light emitters. Overall, highly doped p-GaN is a key element to develop light emitting devices for the DOE SSL program. The project was focused on material research for highly doped p-type GaN materials and device structures for applications in high performance light emitters for general illumination P-GaN and p-AlGaN layers and multi-layer structures were grown by HVPE and investigated in terms of surface morphology and structure, doping concentrations and profiles, optical, electrical, and structural properties. Tasks of the project were successfully accomplished. Highly doped GaN materials with p-type conductivity were fabricated. As-grown GaN layers had concentration N{sub a}-N{sub d} as high as 3 x 10{sup 19} cm{sup -3}. Mechanisms of doping were investigated and results of material studies were reported at several International conferences providing better understanding of p-type GaN formation for Solid State Lighting community. Grown p-type GaN layers were used as substrates for blue and green InGaN-based LEDs made by HVPE technology at TDI. These results proved proposed technical approach and facilitate fabrication of highly conductive p-GaN materials by low-cost HVPE technology for solid state lighting applications. TDI has started the commercialization of p-GaN epitaxial materials.

Vladimir Dmitriev

2007-06-30T23:59:59.000Z

203

Effect of co-doped SnO{sub 2} nanoparticles on photoluminescence of cu-doped potassium lithium borate glass  

Science Conference Proceedings (OSTI)

The SnO{sub 2} co-doped lithium potassium borate glasses doped with 0.05, 0.10, 0.25 and 0.50 mol% of Cu were synthesized by the melt quenching technique. The SnO{sub 2} co-dope was added to the compounds in the amounts of 0.05, 0.10, and 0.20 mol%. The photoluminescent spectrum for different concentrations of copper was studied. It was observed that the intensity of blue emission (450, 490 nm) varies with concentration mol%. In addition, with different concentration of SnO{sub 2} to 0.10 mol% Cu, the influence of the luminescence has been observed to enhance intensity and shifted to blue and red (490, 535 nm) emissions.

Namma, Haydar Aboud; Wagiran, H.; Hussin, R.; Ariwahjoedi, B. [Department of Physics, Universiti Teknologi Malaysia, Skudai 81310, Malaysia and Baghdad College of Economic Sciences University (Iraq); Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, 31750 Tronoh (Malaysia)

2012-09-26T23:59:59.000Z

204

Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes  

Science Conference Proceedings (OSTI)

We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S

2007-02-15T23:59:59.000Z

205

Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes  

DOE R&D Accomplishments (OSTI)

We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

2007-02-20T23:59:59.000Z

206

Doping Cu{sub 2}O in Electrolyte Solution: Dopant Incorporation, Atomic Structures and Electrical Properties  

Science Conference Proceedings (OSTI)

We have pursued a number of research activities between April 2010 and April 2011: ? A detailed study on n-type doping in Cu2O by Br; ? An analysis of natural resource limitations to terawatt-scale solar cells; ? Attempt to achieve a 1.4-eV direct band gap in Ni sulfides (NiSx); ? First-principles studies of doping in Cu2O and electronic structures of NiSx.

Tao, Meng; Zhang, Qiming

2013-11-24T23:59:59.000Z

207

Defects in Photovoltaic Materials and the Origins of Failure to Dope Them: Preprint  

DOE Green Energy (OSTI)

I will review the basic physical principles underlying the formation energy of various intrinsic defects in common photovoltaic materials. I then use the above principles to explain why doping of semiconductors is, in general, limited and which design principles can be used to circumvent such limits. This work can help design strategies of doping absorber materials as well as explain how TCOs work. Recent results on the surprising stability of polar (112)+ surfaces of CIS will also be described in this context.

Zunger, A.; Kilic, C.; Wang, L.

2002-05-01T23:59:59.000Z

208

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer  

DOE Patents (OSTI)

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO{sub 3} particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO{sub 3} particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr{sub 2}O{sub 3} on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO{sub 3} layer coated with CaO and Cr{sub 2}O{sub 3} surface deposit at from about 1,000 C to 1,200 C to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO{sub 3} layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power. 5 figs.

Singh, P.; Ruka, R.J.

1995-02-14T23:59:59.000Z

209

Temperature Dependence of Aliovalent-vanadium Doping in LiFePO4 Cathodes  

Science Conference Proceedings (OSTI)

Vanadium-doped olivine LiFePO4 cathode materials have been synthesized by a novel low-temperature microwave-assisted solvothermal (MW-ST) method at 300 oC. Based on chemical and powder neutron/X-ray diffraction analysis, the compositions of the synthesized materials were found to be LiFe1-3x/2Vx x/2PO4 (0 x 0.2) with the presence of a small number of lithium vacancies charge-compensated by V4+, not Fe3+, leading to an average oxidation state of ~ 3.2+ for vanadium. Heating the pristine 15 % V-doped sample in inert or reducing atmospheres led to a loss of vanadium from the olivine lattice with the concomitant formation of a Li3V2(PO4)3 impurity phase; after phase segregation, a partially V-doped olivine phase remained. For comparison, V-doped samples were also synthesized by conventional ball milling and heating, but only ~ 10 % V could be accommodated in the olivine lattice in agreement with previous studies. The higher degree of doping realized with the MW-ST samples demonstrates the temperature dependence of the aliovalent-vanadium doping in LiFePO4.

Harrison, Katharine L [University of Texas at Austin; Bridges, Craig A [ORNL; Paranthaman, Mariappan Parans [ORNL; Idrobo Tapia, Juan C [ORNL; Manthiram, Arumugam [University of Texas at Austin; Goodenough, J. B. [University of Texas at Austin; Segre, C [Illinois Institute of Technology; Katsoudas, John [Illinois Institute of Technology; Maroni, V. A. [Argonne National Laboratory (ANL)

2013-01-01T23:59:59.000Z

210

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer  

SciTech Connect

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO.sub.3 particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr.sub.2 O.sub.3 on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO.sub.3 layer coated with CaO and Cr.sub.2 O.sub.3 surface deposit at from about 1000.degree. C. to 1200.degree. C. to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO.sub.3 layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power.

Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Pittsburgh, PA)

1995-01-01T23:59:59.000Z

211

Usage of antimony segregation for selective doping of Si in molecular beam epitaxy  

SciTech Connect

An original approach to selective doping of Si by antimony (Sb) in molecular beam epitaxy (MBE) is proposed and verified experimentally. This approach is based on controllable utilization of the effect of Sb segregation. In particular, the sharp dependence of Sb segregation on growth temperature in the range of 300-550 deg. C is exploited. The growth temperature variations between the kinetically limited and maximum segregation regimes are suggested to be utilized in order to obtain selectively doped structures with abrupt doping profiles. It is demonstrated that the proposed technique allows formation of selectively doped Si:Sb layers, including delta ({delta}-)doped layers in which Sb concentrations can be varied from 5 x 10{sup 15} to 10{sup 20} cm{sup -3}. The obtained doped structures are shown to have a high crystalline quality and the short-term growth interruptions, which are needed to change the substrate temperature, do not lead to any significant accumulation of background impurities in grown samples. Realization of the proposed approach requires neither too low (<300 deg. C), nor too high (>600 deg. C) growth temperatures or any special equipment for the MBE machines.

Yurasov, D. V.; Drozdov, M. N.; Murel, A. V.; Shaleev, M. V.; Novikov, A. V. [Institute for Physics of Microstructures Russian Academy of Sciences, 603950, Nizhny Novgorod, GSP-105 (Russian Federation); Zakharov, N. D. [Max-Planck-Institut fur Mikrostrukturphysik, Weinberg 2, 06120 Halle/Saale (Germany)

2011-06-01T23:59:59.000Z

212

Photoluminescence of samarium-doped TiO{sub 2} nanotubes  

SciTech Connect

Samarium (Sm)-modified TiO{sub 2} nanotubes (TNTs) were synthesized by low-temperature soft chemical processing. X-ray powder diffraction analyses of the synthesized Sm-doped and non-doped TNTs show a broad peak near 2{theta}=10{sup o}, which is typical of TNTs. The binding energy of Sm {sup 3}d{sub 5/2} for 10 mol% Sm-doped TNT (1088.3 eV) was chemically shifted from that of Sm{sub 2}O{sub 3} (1087.5 eV), showing that Sm existed in the TiO{sub 2} lattice. Sm-doped TNTs clearly exhibited red fluorescence, corresponding to the doped Sm{sup 3+} ion in the TNT lattice. The Sm-doped TNT excitation spectrum exhibited a broad curve, which was similar to the UV-vis optical absorption spectrum. Thus, it was considered that the photoluminescence emission of Sm{sup 3+}-doped TNT with UV-light irradiation was caused by the energy transfer from the TNT matrix via the band-to-band excitation of TiO{sub 2} to the Sm{sup 3+} ion. - Graphical Abstract: Samarium-doped TiO{sub 2} nanotubes (TNTs) having a nanotubular structure were synthesized by soft chemical route. It was revealed that the energy associated by the band-to-band excitation of TNT matrix transferred to the doped Sm{sup 3+} ions in the lattice, resulting in emission of strong and visible red fluorescence. Highlights: > Sm-doped TiO{sub 2} nanotubes synthesized by low-temperature soft chemical processing. > Sm{sup 3+} substitutes Ti{sup 4+} ions in the nanotube lattice. > Clear fluorescent emission due to the f-f transition at the Sm{sup 3+} in a crystal field environment. > Band-to-band excitation of TiO{sub 2} and followed energy transfer to Sm{sup 3+} causes the luminescence.

Park, Dong Jin [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Sekino, Tohru, E-mail: sekino@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Tsukuda, Satoshi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Hayashi, Asuka [Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kusunose, Takafumi [Faculty of Engineering, Kagawa University, Hayashi 2217-20, Takamatsu, Kagawa 761-0396 (Japan); Tanaka, Shun-Ichiro [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

2011-10-15T23:59:59.000Z

213

Characterization of B2H6 Plasma Doping for Converted p+ Poly-Si Gate  

SciTech Connect

We have investigated the characteristics of B2H6 plasma doping (PLAD) process used to convert the n+ doped poly-Si gate to the p+ poly-Si gate for pMOS. The throughput of the PLAD process is much higher than a conventional beam line implantation process at low energy and high dose ranges. The B2H6 plasma counter-doping on the n+ poly-Si were performed in the energy range of 5kV {approx} 9kV and dose of {approx}E16 number sign /cm2. The B2H6 Plasma doped poly-Si layers were characterized by TDS, SIMS, AFM, and TEM.The TDS analysis showed hydrogen desorption from the B2H6 plasma doped p+ poly-Si layer at a low temperature. The surface concentration of PLAD doped boron was much higher compared to the conventional beam line implantation. However, a serious loss of surface dopant was also observed during photoresist strip and post cleaning. The surface dopant loss could be suppressed by 10% with optimization of the cleaning condition, leading to improve characteristics of PLAD doped p+ poly-Si pMOS, compared to the beam line implantation. Moreover, flat band voltage (VFB) shift was not observed in the C-V curves and there was no significant difference in I-V characteristics between PLAD and the conventional ion implantation. Deeper and higher dopant profile will be helpful to decrease required dose gap between PLAD and beam line implantation.

Oh, Jae-Geun; Lee, J. K.; Hwang, S. H.; Cho, H. J.; Sohn, Y. S.; Sheen, D. S.; Pyi, S. H. [Hynix Semiconductor Inc., San 136-1 Ami-ri, Bubal-eub, Ichon-si, Kyoungki-do, 467-701 (Korea, Republic of); Lee, S. W.; Hahn, S. H. [Varian Korea Ltd., 433-1 Mogok-dong Pyeongtaek-si Kyoungki-do 459-040 (Korea, Republic of); Jeon, Y. B.; Fang, Z.; Singh, V. [Varian Semiconductor Equipment Associates Incorporate, 35 Dory Road, Gloucester, MA 01930 (United States)

2006-11-13T23:59:59.000Z

214

Impurity-doped optical shock, detonation and damage location sensor  

DOE Patents (OSTI)

A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack.

Weiss, Jonathan D. (Albuquerque, NM)

1995-01-01T23:59:59.000Z

215

Impurity-doped optical shock, detonation and damage location sensor  

DOE Patents (OSTI)

A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack. 8 figs.

Weiss, J.D.

1995-02-07T23:59:59.000Z

216

DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE  

DOE Green Energy (OSTI)

Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed.

Angela D. Lueking; Qixiu Li; John V. Badding; Dania Fonseca; Humerto Gutierrez; Apurba Sakti; Kofi Adu; Michael Schimmel

2010-03-31T23:59:59.000Z

217

Nonlinear optical coupler using a doped optical waveguide  

DOE Patents (OSTI)

An optical mode coupling apparatus includes an Erbium-doped optical waveguide in which an optical signal at a signal wavelength propagates in a first spatial propagation mode and a second spatial propagation mode of the waveguide. The optical signal propagating in the waveguide has a beat length. The coupling apparatus includes a pump source of perturbational light signal at a perturbational wavelength that propagates in the waveguide in the first spatial propagation mode. The perturbational signal has a sufficient intensity distribution in the waveguide that it causes a perturbation of the effective refractive index of the first spatial propagation mode of the waveguide in accordance with the optical Kerr effect. The perturbation of the effective refractive index of the first spatial propagation mode of the optical waveguide causes a change in the differential phase delay in the optical signal propagating in the first and second spatial propagation modes. The change in the differential phase delay is detected as a change in the intensity distribution between two lobes of the optical intensity distribution pattern of an output signal. The perturbational light signal can be selectively enabled and disabled to selectively change the intensity distribution in the two lobes of the optical intensity distribution pattern.

Pantell, Richard H. (Menlo Park, CA); Sadowski, Robert W. (Stanford, CA); Digonnet, Michel J. F. (Palo Alto, CA); Shaw, Herbert J. (Stanford, CA)

1994-01-01T23:59:59.000Z

218

Hafnium-doped tantalum oxide high-k gate dielectric films for future CMOS technology  

E-Print Network (OSTI)

A novel high-k gate dielectric material, i.e., hafnium-doped tantalum oxide (Hf-doped TaOx), has been studied for the application of the future generation metal-oxidesemiconductor field effect transistor (MOSFET). The film's electrical, chemical, and structural properties were investigated experimentally. The incorporation of Hf into TaOx impacted the electrical properties. The doping process improved the effective dielectric constant, reduced the fixed charge density, and increased the dielectric strength. The leakage current density also decreased with the Hf doping concentration. MOS capacitors with sub-2.0 nm equivalent oxide thickness (EOT) have been achieved with the lightly Hf-doped TaOx. The low leakage currents and high dielectric constants of the doped films were explained by their compositions and bond structures. The Hf-doped TaOx film is a potential high-k gate dielectric for future MOS transistors. A 5 �� tantalum nitride (TaNx) interface layer has been inserted between the Hf-doped TaOx films and the Si substrate to engineer the high-k/Si interface layer formation and properties. The electrical characterization result shows that the insertion of a 5 �� TaNx between the doped TaOx films and the Si substrate decreased the film's leakage current density and improved the effective dielectric constant (keffective) value. The improvement of these dielectric properties can be attributed to the formation of the TaOxNy interfacial layer after high temperature O2 annealing. The main drawback of the TaNx interface layer is the high interface density of states and hysteresis, which needs to be decreased. Advanced metal nitride gate electrodes, e.g., tantalum nitride, molybdenum nitride, and tungsten nitride, were investigated as the gate electrodes for atomic layer deposition (ALD) HfO2 high-k dielectric material. Their physical and electrical properties were affected by the post metallization annealing (PMA) treatment conditions. Work functions of these three gate electrodes are suitable for NMOS applications after 800�°C PMA. Metal nitrides can be used as the gate electrode materials for the HfO2 high-k film. The novel high-k gate stack structures studied in this study are promising candidates to replace the traditional poly-Si-SiO2 gate stack structure for the future CMOS technology node.

Lu, Jiang

2005-12-01T23:59:59.000Z

219

Properties of In-Doped ZnO Films Grown by Metalorganic Chemical Vapor Deposition on GaN(0001) Templates  

E-Print Network (OSTI)

TCO is amor- phous indium tin oxide (ITO), most commonlythe properties of indium-doped zinc oxide layers grown byoxide, doping, n-type, MOCVD, metalorganic chemical vapor deposition, ZnO: In, indium

Ben-Yaacov, Tammy; Ive, Tommy; Walle, Chris G.; Mishra, Umesh K.; Speck, James S.; Denbaars, Steven P.

2010-01-01T23:59:59.000Z

220

Phase stabilization and characterization of nanocrystalline Fe-doped Cu{sub 2}O  

SciTech Connect

Oxide-based ferromagnetic semiconductors are currently being explored for spin-based electronics (Spintronics) applications. Specimens of 1 and 2% Fe-doped Cu{sub 2}O were prepared by varying the parameters of chemical co-precipitation technique. XRD analysis confirmed the cubic structure of Cu{sub 2}O. Single-phase structure was obtained for the 1% Fe-doped Cu{sub 2}O, whereas for the 2% Fe-doped Cu{sub 2}O material, secondary phases were present (either CuO or Fe{sub 3}O{sub 4}). The morphology and composition were characterized by SEM and EDAX. Measurements made by vibrating sample magnetometry (VSM) indicated paramagnetic behavior at 300 K and diamagnetic behavior at 77 K for the 1% Fe-doped Cu{sub 2}O. Diffuse reflectance (DRS) measurements indicated that a red shift in the band gap of Cu{sub 2}O occurs on doping with Fe.

Joseph, D. Paul; David, T. Premkumar; Raja, S. Philip [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600 025 (India); Venkateswaran, C. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600 025 (India)], E-mail: cvunom@hotmail.com

2008-08-15T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Effect of neodymium doping on structure, electrical and optical properties of nanocrystalline ZnO  

SciTech Connect

In this paper, we report effect of Nd doping on structure, electrical and optical properties of nanocrystalline ZnO prepared through a modified ceramic route. The X-ray diffraction and transmission electron microscopy studies reveal that annealed samples are single phase, pure nanocrystalline ZnO. The optical band gap for different compositions, estimated from ultraviolet-visible spectroscopy study, shows a little increasing tendency while doped with Nd for the samples annealed at lower temperature. The dc electrical conductivity of the samples decreases with the increase in Nd concentration. The ac electrical measurements prove the hopping conduction as the dominant mechanism. The results are being explained on the basis of band structural change due to Nd doping in the host lattice and by Correlated Barrier Hopping model. - Highlights: Black-Right-Pointing-Pointer Particle size increases when it is doped (from XRD). Black-Right-Pointing-Pointer XRD peak shifted to lower angle when doped. Black-Right-Pointing-Pointer The dc conductivity decreases with the increase of Nd dopant concentrations. Black-Right-Pointing-Pointer The temperature dependent ac conductivity follows the universal power law.

Roy, B.; Chakrabarty, S. [Department of Physics, University of Burdwan, Burdwan-713 104 (India); Mondal, O., E-mail: oindrila.rng@gmail.com [Department of Physics, University of Burdwan, Burdwan-713 104 (India); Pal, M., E-mail: m_pal@cmeri.res.in [CSIR-Central Mechanical Engineering Research Institute, Durgapur-713 209 (India); Dutta, A., E-mail: dutta_abhigyan@yahoo.co.in [Department of Physics, University of Burdwan, Burdwan-713 104 (India)

2012-08-15T23:59:59.000Z

222

Specific features of photoluminescence properties of copper-doped cadmium selenide quantum dots  

SciTech Connect

The effect of doping with copper on the photoluminescence properties of cadmium selenide quantum dots 4 nm in dimension is studied. The quenching of the excitonic photoluminescence band related to the quantum dots and the appearance of an impurity photoluminescence band in the near-infrared region are observed after doping of the quantum dots with copper. It is established that, on doping of the quantum dots, the photoluminescence kinetics undergoes substantial changes. The photoluminescence kinetics of the undoped quantum dots is adequately described by a sum of exponential relaxation relations, whereas the photoluminescence kinetics experimentally observed in the region of the impurity band of the copper-doped samples follows stretched exponential decay, with the average lifetimes 0.3-0.6 {mu}s at the photon energies in the range of 1.47-1.82 eV. The experimentally observed changes in the photoluminescence properties are attributed to transformation of radiative centers in the quantum dots when doped with copper atoms.

Tselikov, G. I., E-mail: gleb@vega.phys.msu.ru [Moscow State University, Faculty of Physics (Russian Federation); Dorofeev, S. G.; Tananaev, P. N. [Moscow State University, Faculty of Chemistry (Russian Federation); Timoshenko, V. Yu. [Moscow State University, Faculty of Physics (Russian Federation)

2011-09-15T23:59:59.000Z

223

Structural Environment of Nitrogen in N-doped Rutile TiO2(110)  

DOE Green Energy (OSTI)

We employ x-ray photoelectron spectroscopy (XPS), reflection high-energy electron diffraction (RHEED) and nuclear reaction analysis (NRA) to characterize the concentration-dependent structural properties of nitrogen doping into rutile TiO2. High quality N-doped TiO2 were prepared on rutile single crystal TiO2(110) substrates using plasma-assisted molecular beam epitaxy with an electron cyclotron resonance (ECR) plasma and Ti effusive sources. Films with N dopant concentrations at or below 2 at.% exhibited predominately substitutional doping based on NRA data, whereas films with concentrations above this limit resulted in little or no substitutional N and surfaces rich in Ti3+. The binding energy of the N 1s feature in XPS did not readily distinguish between these two extremes in N-doping, rendering features within 0.4 eV of each other and similar peak profiles. Although widely used to characterize the state of N in anion-doped TiO2 materials, we find that XPS is unsuitable for this task.

Henderson, Michael A.; Shutthanandan, V.; Ohsawa, Takeo; Chambers, Scott A.

2010-12-31T23:59:59.000Z

224

Nitrogen-Doped Mesoporous Carbon for Carbon Capture A Molecular Simulation Study  

Science Conference Proceedings (OSTI)

Using molecular simulation, we investigate the effect of nitrogen doping on adsorption capacity and selectivity of CO{sub 2} versus N{sub 2} in model mesoporous carbon. We show that nitrogen doping greatly enhances CO{sub 2} adsorption capacity; with a 7 wt % dopant concentration, the adsorption capacity at 1 bar and 298 K increases from 3 to 12 mmol/g (or 48% uptake by weight). This great enhancement is due to the preferred interaction between CO{sub 2} and the electronegative nitrogen. The nitrogen doping coupled with the mesoporosity also leads to a much higher working capacity for adsorption of the CO{sub 2}/N{sub 2} mixture in nitrogen-doped mesoporous carbon. In addition, the CO{sub 2}/N{sub 2} selectivity is almost 5 times greater than in nondoped carbon at ambient conditions. This work indicates that nitrogen doping is a promising strategy to create mesoporous carbons for high-capacity, selective carbon capture.

Babarao, Ravichandar [ORNL; Dai, Sheng [ORNL; Jiang, Deen [ORNL

2012-01-01T23:59:59.000Z

225

H.sub.2O doped WO.sub.3, ultra-fast, high-sensitivity hydrogen sensors  

DOE Patents (OSTI)

An ultra-fast response, high sensitivity structure for optical detection of low concentrations of hydrogen gas, comprising: a substrate; a water-doped WO.sub.3 layer coated on the substrate; and a palladium layer coated on the water-doped WO.sub.3 layer.

Liu, Ping (Denver, CO); Tracy, C. Edwin (Golden, CO); Pitts, J. Roland (Lakewood, CO); Lee, Se-Hee (Lakewood, CO)

2011-03-22T23:59:59.000Z

226

Effect of carbazoleoxadiazole excited-state complexes on the efficiency of dye-doped light-emitting diodes  

E-Print Network (OSTI)

a profound effect on the external quantum efficiency of dye-doped organic light-emitting diodes employing Institute of Physics. DOI: 10.1063/1.1469692 I. INTRODUCTION Thin-film organic light-emitting diodes LEDsEffect of carbazole­oxadiazole excited-state complexes on the efficiency of dye-doped light-emitting

227

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells  

E-Print Network (OSTI)

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells. de Bariloche, Argentina 3 ECN Solar Energy, High Tech Campus, Building 5, 5656 AE Eindhoven energy-loss spectroscopy (EELS) is used to study p-doped layers in n-i-p amorphous thin film Si solar

Dunin-Borkowski, Rafal E.

228

Schottky barrier amorphous silicon solar cell with thin doped region adjacent metal Schottky barrier  

DOE Patents (OSTI)

A Schottky barrier amorphous silicon solar cell incorporating a thin highly doped p-type region of hydrogenated amorphous silicon disposed between a Schottky barrier high work function metal and the intrinsic region of hydrogenated amorphous silicon wherein said high work function metal and said thin highly doped p-type region forms a surface barrier junction with the intrinsic amorphous silicon layer. The thickness and concentration of p-type dopants in said p-type region are selected so that said p-type region is fully ionized by the Schottky barrier high work function metal. The thin highly doped p-type region has been found to increase the open circuit voltage and current of the photovoltaic device.

Carlson, David E. (Yardley, PA); Wronski, Christopher R. (Princeton, NJ)

1979-01-01T23:59:59.000Z

229

Method for making defect-free zone by laser-annealing of doped silicon  

DOE Patents (OSTI)

This invention is a method for improving the electrical properties of silicon semiconductor material. The method comprises irradiating a selected surface layer of the semiconductor material with high-power laser pulses characterized by a special combination of wavelength, energy level, and duration. The combination effects melting of the layer without degrading electrical properties, such as minority-carrier diffusion length. The method is applicable to improving the electrical properties of n- and p-type silicon which is to be doped to form an electrical junction therein. Another important application of the method is the virtually complete removal of doping-induced defects from ion-implanted or diffusion-doped silicon substrates.

Narayan, Jagdish (Knoxville, TN); White, Clark W. (Oak Ridge, TN); Young, Rosa T. (Knoxville, TN)

1980-01-01T23:59:59.000Z

230

Transition-Metal Strings Templated on Boron-Doped Carbon Nanotubes: A DFT Investigation  

SciTech Connect

The binding nature, magnetic, and electronic properties of transition-metal (TM) monatomic chains anchored on boron-doped single-walled carbon nanotubes (B-SWCNTs) are studied using density-functional theory. The TM systems studied here include Au, Pt, Ru, Pd, Ag, Co, Ni, Cu, W, and Ti, which are well-known for their technical importance. In conjunction, prototype semiconducting SWCNT(8,0) and metallic SWCNT(6,6) were chosen to model the general features of B-doped SWCNTs. It is found that the TM-strings exhibit well-defined covalent bonds with the boron-doped SWCNTs, in contrast to the pristine SWCNTs. The TMstring/ B-SWCNT composites exhibit high stability and unexpected electronic properties, which are relevant to applications in nanoelectronics, spintronics, nanocatalysis, and sensor devices.

An, Wei; Turner, C. H.

2009-08-27T23:59:59.000Z

231

Cation dopant distributions in nanostructures of transition-metal doped ZnO:Monte Carlo simulations  

SciTech Connect

The path from trace doping to solid solution formation involves an intermediate regime in which the doping level is a few to several atomic percent. In this regime, dopant-dopant interactions, which are driven by the spatial arrangement of dopants, are critical factors in determining the resulting properties. Conventional wisdom counts on simple probabilistic methods for predicting dopant distributions. Here, we use Monte Carlo simulations to show that widely used, straightforward statistical models, such as that of Behringer1, are accurate only in the limit of infinitesimally small surface–to-volume ratio. For epitaxial films and nanoparticles, where much of the current interest resides, dopant distributions depend strongly on the surface-to-volume ratio. We present empirical expressions that accurately predict dopant bonding configurations as a function of film or particle size, shape and dopant concentration for doped ZnO, a material of particular interest in semiconductor spintronics.

Droubay, Timothy; Kaspar, Tiffany C.; Kaspar, Bryce P.; Chambers, Scott A.

2009-02-01T23:59:59.000Z

232

Electrochemical impedance spectroscopy studies of lithium diffusion in doped manganese oxide  

DOE Green Energy (OSTI)

Cathode performance is critical to lithium ion rechargeable battery performance; effects of doping lithium manganese oxide cathode materials on cathode performance are being investigated. In this paper, Li diffusion in Al-doped LiMn{sub 2}O{sub 4} was studied and found to be controlled by the quantity of Al dopant. Electrochemical cycling was conducted at 0.5mA/cm{sub 2}; electrochemical impedance spectra were taken at open circuit potential, with impedance being measured at 65 kHz-0.01 Hz. As the Al dopant level was increased, the Li diffusion rate decreased; this was attributed to the decreased lattice parameter of the doped oxide.

Johnson, B.J.; Doughty, D.H.; Voigt, J.A.; Boyle, T.J.

1996-06-01T23:59:59.000Z

233

OPTIMUM ENERGY ABSORPTION OF A SHORT-PULSE LASER IN A DOPED DIELECTRIC SLAB  

SciTech Connect

A model is used to calculate energy absorption efficiency when a short-pulse laser impinges on a dielectric slab doped with an impurity for which the electrons have a resonant line at the laser wavelength. The amount of the energy resonant absorption is due to the overlapping between laser spectrum and resonance spectrum. The energy absorption efficiency can be maximized for a certain degree of doping concentration (at a given pulselength) and also for a certain pulselength (at a given doping concentration). For a modest amount of impurity, the resonant absorption may increase the fraction of energy absorption up to tens of percent of laser energy at 100s optical cycles when the laser wavelength is tuned within 1% of the resonant line. Dimensionless parameters are constructed so that the scaling to various parameters: laser wavelength, laser pulselength, dielectric constant, slab thickness, impurity concentration, resonant linewidth, and separation between the laser wavelength and the line resonance, could easily be obtained.

L. ANG

2001-05-01T23:59:59.000Z

234

Synthesis and characterization of discrete luminescent erbium-doped silicon nanocrystals  

SciTech Connect

The preparation of discrete erbium-doped silicon nanoparticles prepared by the co-pyrolysis of disilane and the volatile complex Er(tmhd){sub 3} (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionato) is described. The nanoparticles were characterized by transmission electron microscopy, selected area electron diffraction, X-ray dispersive spectroscopy, photoluminescence, and UV-visible absorption spectroscopies. Erbium-doped silicon nanoparticles possess a distinctive dark contrast in the transmission electron microscope, and the presence of erbium is confirmed by X-ray energy dispersive spectroscopy. The mean diameter of the nanoparticle aggregates can be shifted by altering the length of the pyrolysis oven employed. Characteristic Er{sup 3+} near-infrared photoluminescence at 1,540 nm is detected in these doped nanoparticles; preliminary excitation and power dependence measurements of this luminescence suggest a carrier-mediated emission mechanism.

John, J.S.; Coffer, J.L.; Chen, Y.; Pinizzotto, R.F.

1999-03-10T23:59:59.000Z

235

Processing and Characterization of P-Type Doped Zinc Oxide Thin Films  

E-Print Network (OSTI)

Applications of zinc oxide (ZnO) for optoelectronic devices, including light emitting diodes, semiconductor lasers, and solar cells have not yet been realized due to the lack of high-quality p-type ZnO. In the research presented herein, pulsed laser deposition is employed to grow Ag-doped ZnO thin films, which are characterized in an attempt to understand the ability of Ag to act as a p-type dopant. By correlating the effects of the substrate temperature, oxygen pressure, and laser energy on the electrical and microstructural properties of Ag-doped ZnO films grown on c-cut sapphire substrates, p-type conductivity is achieved under elevated substrate temperatures. Characteristic stacking fault features have been continuously observed by transmission electron microscopy in all of the p-type films. Photoluminescence studies on n-type and p-type Ag-doped ZnO thin films demonstrate the role of stacking faults in determining the conductivity of the films. Exciton emission attributed to basal plane stacking faults suggests that the acceptor impurities are localized nearby the stacking faults in the n-type films. The photoluminescence investigation provides a correlation between microstructural characteristics and electrical properties of Ag- doped ZnO thin films; a link that enables further understanding of the doping nature of Ag impurities in ZnO. Under optimized deposition conditions, various substrates are investigated as potential candidates for ZnO thin film growth, including r -cut sapphire, quartz, and amorphous glass. Electrical results indicated that despite narrow conditions for obtaining p-type conductivity at a given substrate temperature, flexibility in substrate choice enables improved electrical properties. In parallel, N+-ion implantation at elevated temperatures is explored as an alternative approach to achieve p-type ZnO. The ion implantation fluence and temperature have been optimized to achieve p-type conductivity. Transmission electron microscopy reveals that characteristic stacking fault features are present throughout the p-type films, however in n-type N-doped films high-density defect clusters are observed. These results suggest that the temperature under which ion implantation is performed plays a critical role in determining the amount of dynamic defect re- combination that can take place, as well as defect cluster formation processes. Ion implantation at elevated temperatures is shown to be an effective method to introduce increased concentrations of p-type N dopants while reducing the amount of stable post-implantation disorder. Finally, the fabrication and properties of p-type Ag-doped ZnO/n-type ZnO and p-type N-doped ZnO/n-type ZnO thin film junctions were reported. For the N-doped sample, a rectifying behavior was observed in the I-V curve, consistent with N-doped ZnO being p-type and forming a p-n junction. The turn-on voltage of the device was ?2.3 V under forward bias. The Ag-doped samples did not result in rectifying behavior as a result of conversion of the p-type layer to n-type behavior under the n- type layer deposition conditions. The systematic studies in this dissertation provide possible routes to grow p-type Ag-doped ZnO films and in-situ thermal activation of N-implanted dopant ions, to overcome the growth temperature limits, and to push one step closer to the future integration of ZnO-based devices.

Myers, Michelle Anne

2013-05-01T23:59:59.000Z

236

Evolution of Magnetic Oxygen States in Sr-Doped LaCoO3  

SciTech Connect

Magnetism in La1-xSrxCoO3 as a function of doping is investigated with x-ray absorption spectroscopy and x-ray magnetic circular dicrhoism at the O K edge, and corresponding first principles electronic structure calculations. For small x, the spectra are consistent with the formation of ferromagnetic clusters occurring within a nonmagnetic insulating matrix. Sr-induced, magnetic O-hole states form just above EF and grow with increasing Sr doping. Density functional calculations for x=0 yield a nonmagnetic ground state with the observed rhombohedral distortion and indicates that doping introduces holes at the Fermi level in magnetic states with significant O 2p and Co t2g character for the undistorted pseudocubic structure. Supercell calculations show stronger magnetism on oxygen atoms having more Sr neighbors.

Medling, S.; Lee, Yuen; Zheng, H.; Mitchell, J.F.; Freeland, J.W.; Harmon, Bruce N.; Bridges, F.

2012-10-12T23:59:59.000Z

237

Mg doping of GaN grown by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions  

SciTech Connect

Acceptor doping of GaN with Mg during plasma-assisted molecular beam epitaxy, under N-rich conditions and a relatively high growth temperature of 740 deg. C, was investigated. The p-doping level steadily increases with increasing Mg flux. The highest doping level achieved, determined from Hall measurements, is 2.1x10{sup 18} cm{sup -3}. The corresponding doping efficiency and hole mobility are approx4.9% and 3.7 cm{sup 2}/V s at room temperature. Cross-sectional transmission electron microscopy and photoluminescence measurements confirm good crystalline and optical quality of the Mg-doped layers. An InGaN/GaN quantum dot light emitting diode (lambda{sub peak}=529 nm) with p-GaN contact layers grown under N-rich condition exhibits a low series resistance of 9.8 OMEGA.

Zhang Meng; Bhattacharya, Pallab; Guo Wei; Banerjee, Animesh [Department of Electrical Engineering and Computer Science, Solid-State Electronics Laboratory, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2010-03-29T23:59:59.000Z

238

Room-Temperature Ferromagnetism in Ion-Implanted Co-Doped TiO?(110) Rutile  

SciTech Connect

Interest in diluted magnetic semiconductros (DMS) is growing rapidly within the emerging field of spintronics. For example, the ability to efficiently inject spin-polarized carriers into nonmagnetic semiconductor heterostructures creates new and exciting possibilities for utilizing DMS materials in spin-based devices. Several III-V and II-VI semiconductor materials doped with magnetic transition metal elements have been explored. Although these materials show promising behavior in some cases, most exhibit Curie temperatures of ~170 K or less. It has recently been shown that certain oxide semiconductors doped with magnetic transition elements show room-temperature ferromagnetism.

Shutthanandan, V.; Thevuthasan, Suntharampillai; Heald, Steve M.; Droubay, Timothy; Engelhard, Mark H.; Kaspar, Tiffany C.; McCready, David E.; Saraf, Laxmikant V.; Chambers, Scott A.; Mun, B. S.; Hamdan, N. M.; Nachimuthu, Ponnusamy; Taylor, B.; Sears, R.; Sinkovic, Boris

2004-05-31T23:59:59.000Z

239

Lattice location of deuterium in plasma and gas charged Mg doped GaN  

SciTech Connect

The authors have used ion channeling to examine the lattice configuration of deuterium in Mg doped GaN grown by MOCVD. The deuterium is introduced both by exposure to deuterium gas and to ECR plasmas. A density functional approach including lattice relaxation, was used to calculate total energies for various locations and charge states of hydrogen in the wurtzite Mg doped GaN lattice. Computer simulations of channeling yields were used to compare results of channeling measurements with calculated yields for various predicted deuterium lattice configurations.

Wampler, W.R.; Barbour, J.C.; Seager, C.H.; Myers, S.M. Jr.; Wright, A.F.; Han, J.

1999-12-02T23:59:59.000Z

240

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

mobility and other unique features hold great promise for nanoscale electronics and photonics. But without a bandgap, graphene's promise can't be realized. As with monolayer...

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

"Nanocrystal bilayer for tandem catalysis"  

E-Print Network (OSTI)

Part VI. Hydrogenolysis of Ethane, Propane, n-Butane andiso-Butane over Supported Platinum Catalysts. J. Catal. 176,

Yamada, Yusuke

2012-01-01T23:59:59.000Z

242

Bilayer Graphene Gets a Bandgap  

NLE Websites -- All DOE Office Websites (Extended Search)

2009 00:00 Graphene is the two-dimensional crystalline form of carbon whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics...

243

Studies on the properties of sputter-deposited Ag-doped ZnO films  

Science Conference Proceedings (OSTI)

Ag-doped ZnO films were prepared by simultaneous rf magnetron sputtering of ZnO and dc magnetron sputtering of Ag on glass substrate. The influences of dopant content and substrate temperature on the properties of the as-grown films were investigated. ... Keywords: Ag, Electrical and optical properties, Thin films, ZnO

D. R. Sahu

2007-12-01T23:59:59.000Z

244

Magnetic characterizations of sol-gel-produced mn-doped ZnO  

Science Conference Proceedings (OSTI)

Nanoparticles of ZnO doped with 6 at.% Mn were produced by a sol-gel method. X-ray diffraction confirms the hexagonal structure as that of the parent compound ZnO, and high-resolution electron transmission microscopy reveals a single-crystallite lattice. ...

R. Asmatulu; H. Haynes; M. Shinde; Y. H. Lin; Y. Y. Chen; J. C. Ho

2010-01-01T23:59:59.000Z

245

Conductivity anisotropy in the doped Bi{sub 2}Te{sub 3} single crystals  

Science Conference Proceedings (OSTI)

Temperature dependences (temperature range T = 0.5-300 K) of resistivity in the plane of layers and in the direction perpendicular to the layers, and the galvanomagnetic effects in undoped and doped Bi{sub 2}Te{sub 3} single crystals are studied (magnetic field H < 80 kOe, T = 0.5-4.2 K). It is shown that upon doping of Bi{sub 2}Te{sub 3} with the Group III atoms (In and B), conductivity anisotropy increases mainly due to an increase in resistivity in the direction perpendicular to the layers. This fact makes it possible to assume that the atoms of these impurities are incorporated mainly into the van der Waal gaps between the layers upon doping. It is also revealed that, upon doping of Bi{sub 2}Te{sub 3} with In and B, the temperature dependence of conductivity becomes weaker, which indicates an increase in the role of scattering by defects in scattering mechanisms. The concentrations and mobilities of charge carriers, values of the Hall factor conditioned by the anisotropy of effective masses and orientation of ellipsoids with respect to crystallographic axes, areas of the extreme section of the Fermi surface by the plane perpendicular to the direction of the magnetic field, and the Fermi energy are evaluated.

Abdullaev, N. A., E-mail: anadir@azintex.com; Kakhramanov, S. Sh.; Kerimova, T. G.; Mustafayeva, K. M. [Azerbaijan National Academy of Sciences, Institute of Physics (Azerbaijan); Nemov, S. A. [St. Petersburg State Polytechnical University (Russian Federation)

2009-02-15T23:59:59.000Z

246

Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer  

SciTech Connect

Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

Carlson, David E. (Yardley, PA)

1980-01-01T23:59:59.000Z

247

Manganese Doping of Magnetic Iron Oxide Nanoparticles: Tailoring Surface Reactivity for a Regenerable Heavy Metal Sorbent  

SciTech Connect

A method for tuning the analyte affinity of magnetic, inorganic nanostructured sorbents for heavy metal contaminants is described. The manganese-doped iron oxide nanoparticle sorbents have a remarkably high affinity compared to the precursor material. Sorbent affinity can be tuned toward an analyte of interest simply by adjustment of the dopant quantity. The results show that following the Mn doping process there is a large increase in affinity and capacity for heavy metals (i.e., Co, Ni, Zn, As, Ag, Cd, Hg, and Tl). Capacity measurements were carried out for the removal of cadmium from river water and showed significantly higher loading than the relevant commercial sorbents tested for comparison. The reduction in Cd concentration from 100 ppb spiked river water to 1 ppb (less than the EPA drinking water limit of 5 ppb for Cd) was achieved following treatment with the Mn-doped iron oxide nanoparticles. The Mn-doped iron oxide nanoparticles were able to load 1 ppm of Cd followed by complete stripping and recovery of the Cd with a mild acid wash. The Cd loading and stripping is shown to be consistent through multiple cycles with no loss of sorbent performance.

Warner, Cynthia L.; Chouyyok, Wilaiwan; Mackie, Katherine E.; Neiner, Doinita; Saraf, Laxmikant; Droubay, Timothy C.; Warner, Marvin G.; Addleman, Raymond S.

2012-02-28T23:59:59.000Z

248

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites  

SciTech Connect

A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

2002-01-01T23:59:59.000Z

249

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites  

SciTech Connect

A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

1999-01-01T23:59:59.000Z

250

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites  

SciTech Connect

A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

Corman, G.S.; Luthra, K.L.

1999-09-14T23:59:59.000Z

251

B8: Monitoring Oxygen Diffusion in Gd-Doped Ceria by Null ...  

Science Conference Proceedings (OSTI)

A16: Analysis of Surface Physic-Chemical Properties of Titanium Heat Treated · A17: Morphology Variations of GaN Nanowires and Devices ... A21: Synthesis and Characterization of ?-Tricalcium Phosphate / Glutamic acid ... B13: Ionic Conductivity of Doped Ceria Thin Films Using Different Electrode Configurations.

252

Four-wave mixing, quantum control and compensating losses in doped negative-index photonic metamaterials  

E-Print Network (OSTI)

The possibility of compensating absorption in negative-index metatamterials (NIMs) doped by resonant nonlinear-optical centers is shown. The role of quantum interference and extraordinary properties of four-wave parametric amplification of counter-propagating electromagnetic waves in NIMs are discussed.

Popov, Alexander K; George, Thomas F; Shalaev, Vladimir M

2007-01-01T23:59:59.000Z

253

Four-wave mixing, quantum control and compensating losses in doped negative-index photonic metamaterials  

E-Print Network (OSTI)

The possibility of compensating absorption in negative-index metatamterials (NIMs) doped by resonant nonlinear-optical centers is shown. The role of quantum interference and extraordinary properties of four-wave parametric amplification of counter-propagating electromagnetic waves in NIMs are discussed.

Alexander K. Popov; Sergey A. Myslivets; Thomas F. George; Vladimir M. Shalaev

2007-08-01T23:59:59.000Z

254

Work function control of hole-selective polymer/ITO anode contacts: an electrochemical doping study  

Science Conference Proceedings (OSTI)

We present a novel method for electrodeposition of ultra-thin films of poly-3-hexylthiophene (e-P3HT) on chemically modified indium-tin oxide (ITO) electrodes, to produce a hole-selective contact with an easily tuned work function (?), as demonstrated by a combination of spectroelectrochemistry and ultraviolet photoemission spectroscopy (UPS). Selective contacts for optimized charge injection have become essential components for both thin film organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs). Electrochemically doped e-P3HT thin films, using counter ions such as PF{sub 6}{sup ?} do not suffer from stability issues associated with more “acidic” polymer layers (e.g. PEDOT:PSS). By controlling the oxidation state of the e-P3HT film via electrochemical doping we control the charge density within the film, resulting in an increase in work function with an increase in degree of oxidation. The method of electrochemical formation and doping of the e-P3HT film, using either constant potential step (CA) versus pulsed-potential step (PPS) protocols, has a significant secondary impact on the work function, as a result of the interface dipole effects from entrapment of these counter ions in the near-surface region of the polymer film. These results have significance for the performance of both OLEDs and OPVs built on these doped e-P3HT layers.

Ratcliff, Erin L.; Lee, Paul A.; Armstrong, Neal R.

2010-01-01T23:59:59.000Z

255

Electrical and gas sensing properties of self-aligned copper-doped zinc oxide nanoparticles  

Science Conference Proceedings (OSTI)

Electrical and gas sensing properties of nanocrystalline ZnO:Cu, having Cu X wt% (X = 0.0, 0.5, 1.0, and 1.5) in ZnO, in the form of pellet were investigated. Copper chloride and zinc acetate were used as precursors along with oxalic acid as a precipitating reagent in methanol. Material characterization was done by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and inductive coupled plasma with optical emission spectrometry (ICP-OES). FE-SEM showed the self-aligned Cu-doped ZnO nano-clusters with particles in the range of 40-45 nm. The doping of 0.5% of copper changes the electrical conductivity by an order of magnitude whereas the temperature coefficient of resistance (TCR) reduces with increase in copper wt% in ZnO. The material has shown an excellent sensitivity for the H{sub 2}, LPG and CO gases with limited temperature selectivity through the optimized operating temperature of 130, 190 and 220 deg. C for H{sub 2}, LPG and CO gases, respectively at 625 ppm gas concentration. The %SF was observed to be 1460 for H{sub 2} at 1% Cu doping whereas the 0.5% Cu doping offered %SF of 950 and 520 for CO and LPG, respectively. The response and recovery time was found to be 6 to 8 s and 16 s, respectively.

Sonawane, Yogesh S. [Thin Film Laboratory, Department of Physics, University of Pune, Pune 411007 (India); Kanade, K.G. [Department of Chemistry, Mahatma Phule College, Pimpari, Pune 411017 (India); Kale, B.B. [Nanocrystalline Materials Laboratory, Center for Materials for Electronics Technology (CMET), Pune 411008 (India)], E-mail: kbbb1@yahoo.co.in; Aiyer, R.C. [Center for Sensor Studies, Department of Physics, University of Pune, Pune 411007 (India)], E-mail: rca@physics.unipune.ernet.in

2008-10-02T23:59:59.000Z

256

A first-principle study of B- and P-doped silicon quantum dots  

Science Conference Proceedings (OSTI)

Doping of silicon quantum dots (Si QDs) is important for realizing the potential applications of Si QDs in the fields of Si QDsbased all-Si tandem solar cells, thin-film transistors, and optoelectronic devices. Based on the first-principle calculations, ...

Jieqiong Zeng; Hong Yu

2012-01-01T23:59:59.000Z

257

Thickness Dependency of Thin Film Samaria Doped Ceria for Oxygen Sensing  

DOE Green Energy (OSTI)

High temperature oxygen sensors are widely used for exhaust gas monitoring in automobiles. This particular study explores the use of thin film single crystalline samaria doped ceria as the oxygen sensing material. Desired signal to noise ratio can be achieved in a material system with high conductivity. From previous studies it is established that 6 atomic percent samarium doping is the optimum concentration for thin film samaria doped ceria to achieve high ionic conductivity. In this study, the conductivity of the 6 atomic percent samaria doped ceria thin film is measured as a function of the sensing film thickness. Hysteresis and dynamic response of this sensing platform is tested for a range of oxygen pressures from 0.001 Torr to 100 Torr for temperatures above 673 K. An attempt has been made to understand the physics behind the thickness dependent conductivity behavior of this sensing platform by developing a hypothetical operating model and through COMSOL simulations. This study can be used to identify the parameters required to construct a fast, reliable and compact high temperature oxygen sensor.

Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Jiang, Weilin; Varga, Tamas; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

2010-11-23T23:59:59.000Z

258

Hydrogen storage material and process using graphite additive with metal-doped complex hydrides  

DOE Patents (OSTI)

A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

Zidan, Ragaiy (Aiken, SC); Ritter, James A. (Lexington, SC); Ebner, Armin D. (Lexington, SC); Wang, Jun (Columbia, SC); Holland, Charles E. (Cayce, SC)

2008-06-10T23:59:59.000Z

259

Refractive index and density in F- and Cl-doped silica glasses  

Science Conference Proceedings (OSTI)

The refractive index and density of fluorine- and chlorine-doped silica glasses were measured as functions of fictive temperature. The halogen concentrations were observed to have a refractive index or density that is independent of the fictive temperature were found. This implies that these properties are not affected by any heat-treatment conditions.

Kakiuchida, Hiroshi; Shimodaira, Noriaki; Sekiya, Edson H.; Saito, Kazuya; Ikushima, Akira J. [Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511 (Japan); Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511, Japan and Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa, Yokohama, Kanagawa 221-8755 (Japan); Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511 (Japan)

2005-04-18T23:59:59.000Z

260

Li-doped (Ba,Sr)TiO3 thick film interdigital capacitors for microwave applications  

Science Conference Proceedings (OSTI)

Microwave properties of Li-doped (Ba,Sr)TiO"3 thick film interdigital capacitors have been investigated. According to the reported papers, BaSrTiO"3 materials, paraelectric state at the room temperature, have high dielectric permittivity (>500 @ 1MHz) ... Keywords: BST, Microwave properties, Screen printing, Thick film, Tunability

Se-Ho Kim; Jung-Hyuk Koh

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Dye-doped cholesteric-liquid-crystal room-temperature single-photon source*  

E-Print Network (OSTI)

Dye-doped cholesteric-liquid-crystal room-temperature single-photon source* SVETLANA G. LUKISHOVAy, 250 East River Road, Rochester, New York 14623-1299, USA (Received 30 June 2003) Abstract. Fluorescence antibunching from single terrylene molecules embedded in a cholesteric-liquid-crystal host is used

Stroud, Carlos R.

262

Solid State Theory of Photovoltaic Materials: Nanoscale Grain Boundaries and Doping CIGS  

DOE Green Energy (OSTI)

We use modern first-principles electronic structure theory to investigate (1) why are grain boundaries in chalcopyrites passive; (2) can chalcopyrites be doped by transition metals, and; (3) can hot electrons and carrier multiplication be efficient in quantum-dot solar cells.

Zunger, A

2005-01-01T23:59:59.000Z

263

Optical Properties of p-type ZnO Doped by As Ion Implantation  

Science Conference Proceedings (OSTI)

As-doped p-type ZnO has been achieved by ion implantation. The As-related optical properties were analyzed by using secondary ion mass spectrometry, the Raman scattering, and the photoluminescence experiments. From the I-V measurement, the behavior of rectifying on these samples is confirmed.

Jeong, T.S.; Youn, C.J.; Han, M.S. [Semiconductor Physics Research Center (SPRC), Jeonbuk National University, Jeonju 561-756 (Korea, Republic of); Park, Y. S. [Korea Photonics Technolgy Institute (KOPTI), Gwangju 500-210 (Korea, Republic of); Lee, W.S. [Department of Electrical Engineering, Chosun University, Gangju 501-759 (Korea, Republic of)

2005-06-30T23:59:59.000Z

264

Aluminum-doped lithium nickel cobalt oxide electrodes for high-power lithium-ion batteries.  

DOE Green Energy (OSTI)

Non-doped and aluminum-doped LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cathodes from three industrial developers coupled with graphite anodes were made into lithium-ion cells for high-power applications. The powder morphology of the active cathode materials was examined by a scanning electron microscope. The electrochemical performance of these cells was investigated by hybrid pulse power characterization (HPPC) testing, accelerated aging, and AC impedance measurement of symmetric cells. Although all of the fresh cells are found to meet and exceed the power requirements set by PNGV, the power capability of those cells with non-doped LiNi {sub 0.8}Co{sub 0.2}O{sub 2} cathodes fades rapidly due to the rise of the cell impedance. Al-doping is found very effective to suppress the cell impedance rise by stabilizing the charge-transfer impedance on the cathode side. The stabilization mechanism may be related to the low average oxidation state of nickel ions in the cathode. The powder morphology also plays a secondary role in determining the impedance stabilization.

Chen, C. H.; Liu, J.; Stoll, M. E.; Henriksen, G.; Vissers, D. R.; Amine, K.; Chemical Engineering; Univ. of Science and Technology of China

2004-04-05T23:59:59.000Z

265

Selectively Erbium Doped Titanium Diffused Optical Waveguide Amplifiers in Lithium Niobate  

E-Print Network (OSTI)

Selectively erbium (Er) doped titanium (Ti) in-diffused optical waveguide amplifiers on lithium niobate (LiNbO3) substrate have been fabricated and characterized in the wavelength regime around ? = 1.53?m using counter-directional pumping at ?P = 1.48?m. LiNbO3 waveguide amplifiers are desirable for providing gain in optical circuit chips through integration with other optical elements on a single substrate. A prerequisite for achieving useful gain rests on the optimization of overlap between the incident guided optical signal mode distribution and the evolving emission from excited Er ions. The extent of overlap can be controlled by adjusting fabrication parameters. Fabrication parameters for Er-doped Ti in-diffused waveguide amplifiers of useful optical gain have been optimized by diffusing selective patterns of vacuum-deposited 17nm-thick erbium film at 1100?C for 100 hours into LiNbO3, and integrating with 7?m-wide single mode straight channel waveguides formed by diffusing 1070Å thick titanium film into the LiNbO3. Small-signal gain characterization was carried out with a -30 dBm of transmitted input signal power at ?S=1531nm with counter-directionally launched pump power ranging between 0 to 119mW at ?P=1488nm, using TM polarization for both the signal and pump beams. At a maximum launched pump power of 119mW, a signal enhancement of 8.8dBm for 25mm-long erbium doped region, and 11.6dBm for 35mm-long erbium doped region were obtained. The corresponding calculated net gain values are 1.8dB and 2.8dB, for the 25mm-long and 35mm-long Er-doped regions, respectively.

Suh, Jae Woo

2010-12-01T23:59:59.000Z

266

The Effect of Grain Size and Phosphorous-doping of Polycrystalline 3C-SiC on Infrared Reflectance Spectra  

SciTech Connect

The effect of P-doping and grain size of polycrystalline 3C-SiC on the infrared reflectance spectra is reported. The relationship between grain size and full width at half maximum (FWHM) suggest that the behaviour of the 3C-SiC with the highest phosphorous doping level (of 1.2 x 10{sup 19} at. cm{sup -3}) is different from those with lower doping levels (< 6.6 x 10{sup 18} at. cm{sup -3}). It is also further demonstrated that the plasma resonance frequency (w{sub p}) is not influenced by the grain size.

I. J. van Rooyen; J. A. A. Engelbrecht; A. Henry; E. Janzen; J. H. Neethling; P. M. van Rooyen

2012-03-01T23:59:59.000Z

267

Very heavily electron-doped CrSi2 as a high performance high temperature thermoelectric material  

SciTech Connect

We analyze the thermoelectric behavior, using first principles and Boltzmann transport calculations, of very heavily electron-doped CrSi2 and find that at temperatures of 1250 K and electron dopings of $1-4 \\times10^{21}$ cm$^{-3}$, thermopowers as large or larger in magnitude than 200 $\\mathrm{\\mu}$V/K may be found. Such high thermopowers at such high carrier concentrations are extremely rare, and suggest that good thermolectric performance (i.e. ZT) may be found in these ranges of temperature and doping.

Parker, David S [ORNL; Singh, David J [ORNL

2012-01-01T23:59:59.000Z

268

Interstitial BiO molecule as a center of broadband IR luminescence in bismuth-doped silica glass  

E-Print Network (OSTI)

IR luminescence and absorption in bismuth-doped silica glass-core fibers observed recently (see [arXiv:1106.2969v1 [physics.optics]) are argued to be caused by transitions in interstitial BiO molecules

Sokolov, V O; Dianov, E M

2011-01-01T23:59:59.000Z

269

Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water  

DOE Patents (OSTI)

Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

Moore, Robert C; Holt-Larese, Kathleen C; Bontchev, Ranko

2013-08-13T23:59:59.000Z

270

Characterization of solution processed, p-doped films using hole-only devices and organic field-effect transistors  

Science Conference Proceedings (OSTI)

We report a solution-processed approach for a p-type doped hole transport layer in organic light emitting devices (OLEDs). UV-vis-NIR absorption spectra identified the charge transfer between the donor and acceptor in the solution processed doped films. Single carrier device and field-effect transistor were utilized as test vehicles to study the charge transport property and extract important parameters such as bulk mobile carrier concentration and mobility. OLEDs with p-type doped hole transport layer showed significant improvement in power efficiency up to 30% at the optimal doping ratio. This approach has the great potential to reduce the power consumption for OLED solid state lighting while lowering the cost and boosting the throughput of its manufacturing.

Swensen, James S.; Wang, Liang (Frank); Rainbolt, James E.; Koech, Phillip K.; Polikarpov, Evgueni; Gaspar, Daniel J.; Padmaperuma, Asanga B.

2012-12-01T23:59:59.000Z

271

Structural studies and optical and electrical properties of novel Gd3+-doped Sb2Se3 nanorods  

Science Conference Proceedings (OSTI)

Gd3+-doped Sb2Se3 nanorods were synthesized by coreduction method at 180°C and pH = 12 for 48 h. Powder XRD patterns indicate that the GdxSb2-xSe3 crystals (x ...

Abdolali Alemi; Younes Hanifehpour; Sang Woo Joo; Bong-Ki Min; Tae Hwan Oh

2012-01-01T23:59:59.000Z

272

Characteristics of InGaP/InGaAs pseudomorphic high electron mobility transistors with triple delta-doped sheets  

Science Conference Proceedings (OSTI)

Fundamental and insightful characteristics of InGaP/InGaAs double channel pseudomorphic high electron mobility transistors (DCPHEMTs) with graded and uniform triple {delta}-doped sheets are coomprehensively studied and demonstrated. To gain physical insight, band diagrams, carrier densities, and direct current characteristics of devices are compared and investigated based on the 2D semiconductor simulator, Atlas. Due to uniform carrier distribution and high electron density in the double InGaAs channel, the DCPHEMT with graded triple {delta}-doped sheets exhibits better transport properties, higher and linear transconductance, and better drain current capability as compared with the uniformly triple {delta}-doped counterpart. The DCPHEMT with graded triple {delta}-doped structure is fabricated and tested, and the experimental data are found to be in good agreement with simulated results.

Chu, Kuei-Yi [National Cheng-Kung University, Institute of Microelectronics, Department of Electrical Engineering (China); Chiang, Meng-Hsueh, E-mail: mhchiang@niu.edu.tw; Cheng, Shiou-Ying, E-mail: sycheng@niu.edu.tw [National II an University, Department of Electronic Engineering (China); Liu, Wen-Chau [National Cheng-Kung University, Institute of Microelectronics, Department of Electrical Engineering (China)

2012-02-15T23:59:59.000Z

273

Interplay between intrinsic defects, doping, and free carrier concentration in SrTiO[subscript 3] thin films  

E-Print Network (OSTI)

Using both computational and experimental analysis, we demonstrate a rich point-defect phase diagram in doped strontium titanate as a function of thermodynamic variables such as oxygen partial pressure and electronic ...

Ertekin, Elif

274

Ultra-low resistance ohmic contacts to GaN with high Si doping concentrations grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Ti/Al/Ni/Au ohmic contacts were formed on heavily doped n{sup +} metal-polar GaN samples with various Si doping concentrations grown by molecular beam epitaxy. The contact resistivity (R{sub C}) and sheet resistance (R{sub sh}) as a function of corresponding GaN free carrier concentration (n) were measured. Very low R{sub C} values (electron mobility transistors.

Afroz Faria, Faiza; Guo Jia; Zhao Pei; Li Guowang; Kumar Kandaswamy, Prem; Wistey, Mark; Xing Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

2012-07-16T23:59:59.000Z

275

Modification of the optical and photorefractive properties of Ce-doped strontium--barium niobate by co-doping with a nonphotorefractive La impurity  

Science Conference Proceedings (OSTI)

We demonstrate a possibility to modify photorefractive properties of a ferroelectric crystal by means of controlling the ferroelectric phase transition. This is shown by an example of co-doping a photorefractive SBN-0.61:Ce crystal with a nonphotorefractive La impurity, which strongly lowers the ferroelectric phase transition and in turn drastically enhances the linear electrooptic coefficients. The observed low coercive fields enable us to build in SBN:(Ce+La) a reproducible fast switching of the energy transfer direction. This is done by an electric field switching which changes the sign of the two-beam coupling gain factor {Gamma}. {copyright} 2001 American Institute of Physics.

Volk, T.; Ivleva, L.; Lykov, P.; Isakov, D.; Osiko, V.; Woehlecke, M.

2001-08-06T23:59:59.000Z

276

Electronic structure of delta-doped La:SrTiO{sub 3} layers by hard x-ray photoelectron spectroscopy  

Science Conference Proceedings (OSTI)

We have employed hard x-ray photoemission (HAXPES) to study a delta-doped SrTiO{sub 3} layer that consisted of a 3-nm thickness of La-doped SrTiO{sub 3} with 6% La embedded in a SrTiO{sub 3} film. Results are compared to a thick, uniformily doped La:SrTiO{sub 3} layer. We find no indication of a band offset for the delta-doped layer, but evidence of the presence of Ti{sup 3+} in both the thick sample and the delta-layer, and indications of a density of states increase near the Fermi energy in the delta-doped layer. These results further demonstrate that HAXPES is a powerful tool for the non-destructive investigation of deeply buried doped layers.

Kaiser, A. M. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Peter-Gruenberg-Institut PGI-6, Forschungszentrum Juelich, 52425 Juelich (Germany); Gray, A. X. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Conti, G.; Fadley, C. S. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Jalan, B. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minnesota 55455 (United States); Kajdos, A. P.; Stemmer, S. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Gloskovskii, A. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Ueda, S.; Yamashita, Y.; Kobayashi, K. [NIMS Beamline Station at SPring-8, National Institute for Materials Science, Hyogo 679-5148 (Japan); Drube, W. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg (Germany)

2012-06-25T23:59:59.000Z

277

Scattering and electron mobility in combination-doped HFET-structures AlGaAs/InGaAs/AlGaAs with high electron density  

Science Conference Proceedings (OSTI)

Molecular-beam epitaxy is used for growing structures differing in doping technique and doping level and having a high two-dimensional-electron concentration n{sub s} in the quantum well. The effect of doping combining uniform and {delta} doping on the electron-transport properties of heterostructures is investigated. A new type of structure with a two-sided silicon {delta} doping of GaAs transition layers located on the quantum-well boundaries is proposed. The largest value of electron mobility {mu}{sub H} = 1520 cm{sup 2}/(V s) is obtained simultaneously with a high electron density n{sub s} = 1.37 Multiplication-Sign 10{sup 13} cm{sup -2} at 300 K with such a doping. It is associated with decreasing electron scattering by an ionized impurity, which is confirmed by the carried out calculations.

Khabibullin, R. A., E-mail: khabibullin_r@mail.ru; Vasil'evskii, I. S. [MEPHI National Research Nuclear University (Russian Federation); Galiev, G. B.; Klimov, E. A. [Russian Academy of Sciences, Institute of Ultrahigh-Frequency Semiconductor Electronics (Russian Federation); Ponomarev, D. S. [MEPHI National Research Nuclear University (Russian Federation); Lunin, R. A.; Kulbachinskii, V. A. [Moscow State University (Russian Federation)

2011-10-15T23:59:59.000Z

278

Anodic oxygen-transfer electrocatalysis at iron-doped lead dioxide electrodes  

SciTech Connect

The research illustrated in this thesis was performed under the guidance of Professor Dennis C. Johnson beginning in March 1987. Chapter 2 concentrates on the development and electrocatalytic properties of iron-doped {beta}-PbO{sub 2} films on noble-metal substrates. Chapter 3 focuses attention on the preparation and characterization of iron-doped {beta}-PbO{sub 2} films on titanium substrates (Fe-PbO{sub 2}/Ti). Chapter 4 discusses anodic evolution of ozone at Fe-PbO{sub 2}/Ti electrodes. Chapter 5 describes electrochemical incineration of p-benzoquinone (BQ) at Fe-PbO{sub 2}/Ti electrodes. In addition, the Appendix includes another published paper which is a detailed study of {alpha}-PbO{sub 2} films deposited on various types of stainless steel substrates.

Feng, Jianren

1994-10-01T23:59:59.000Z

279

Unusual Room Temperature Ferromagnetism in Bulk Sintered GaP Doped with Copper  

Science Conference Proceedings (OSTI)

Robust room temperature ferromagnetism is obtained in single phase Gallium Phosphide doped with Cu{sup 2+} prepared by simple solid state reaction route. The saturation magnetization at 300 K is 1.5 times 10{sup -2} emu/g and the coercivity was found to be 125 Oe. A strong ferromagnetic resonance signal confirms the long range magnetic order which persists to temperatures as high as 739 K. X-ray absorption spectroscopy (XAS) indicate that Cu is in a +2 state. Ab initio calculations also show that the ferromagnetic ordering is energetically favorable in Cu doped GaP. When the spin-orbit coupling is included we get an enhanced total magnetic moment of 0.31 muB with a local moment on Cu 0.082 and on P 0.204 mu{sub B}. per atom.

Owens, F. J.; Gupta, A.; Rao, K. V.; Iqbal, Z.; Osorio Guillen, J. M.; Ahuja, R.; Guo, J.-H.

2007-06-01T23:59:59.000Z

280

Relative Humidity Sensing Properties Of Cu{sub 2}O Doped ZnO Nanocomposite  

Science Conference Proceedings (OSTI)

In this paper we report application of Cu{sub 2}O doped ZnO composite prepared by solid state reaction route as humidity sensor. Pellet samples of ZnO-Cu{sub 2}O nanocrystalline powders with 2, 5 and 10 weight% of Cu{sub 2}O in ZnO have been prepared. Pellets have been annealed at temperatures of 200-500 deg. C and exposed to humidity. It is observed that as relative humidity increases, resistance of the pellet decreases for the humidity from 10% to 90%. Sample with 5% of Cu{sub 2}O doped in ZnO and annealed at 500 deg. C shows best results with sensitivity of 1.50 M{omega}/%RH. In this case the hysteresis is low and the reproducibility high, making it the suitable candidate for humidity sensing.

Pandey, N. K.; Tiwari, K.; Tripathi, A.; Roy, A.; Rai, A.; Awasthi, P. [Sensors and Materials Research Laboratory, Department of Physics, University Of Lucknow, U.P., Pin-226007 (India)

2009-06-29T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Study of gadolinia-doped ceria solid electrolyte surface by XPS  

Science Conference Proceedings (OSTI)

Gadolinia-doped ceria (CGO) is an important material to be used as electrolyte for solid oxide fuel cell for intermediate temperature operation. Ceria doped with 10 mol% gadolinia (Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95}) was prepared by conventional solid state synthesis and found to be single phase by room temperature X-ray diffraction (XRD). The chemical states of the surface of the prepared sample were analyzed by X-ray photoelectron spectroscopy (XPS). Though Gd was present in its characteristic chemical state, Ce was found in both Ce{sup 4+} and Ce{sup 3+} states. Presence of Ce{sup 3+} state was ascribed to the differential yield of oxygen atoms in the sputtering process.

Datta, Pradyot [Technische Universitaet Clausthal, Institut fuer Metallurgie, 42 Robert-Koch Strasse, 38678, Clausthal-Zellerfeld (Germany); Max-Planck-Institut fuer Metallforschung and Institut fuer Nichtmetallische and Anorganische Materialien, Universitaet Stuttgart, Pulvermetallurgisches Laboratorium, Heisenbergstrasse 3, Stuttgart 70569 (Germany)], E-mail: pdatta@rediffmail.com; Majewski, Peter [University of South Australia, School of Advanced Manufacturing and Mechanical Engineering, Mawson Institute, Mawson Lakes, SA 5095 (Australia); Aldinger, Fritz [Max-Planck-Institut fuer Metallforschung and Institut fuer Nichtmetallische and Anorganische Materialien, Universitaet Stuttgart, Pulvermetallurgisches Laboratorium, Heisenbergstrasse 3, Stuttgart 70569 (Germany)

2009-02-15T23:59:59.000Z

282

Spectroscopy of Charge Carriers and Traps in Field-Doped Organic Semiconductors  

SciTech Connect

This research project aims to achieve quantitative and molecular level understanding of charge carriers and traps in field-doped organic semiconductors via in situ optical absorption spectroscopy, in conjunction with time-resolved electrical measurements. During the funding period, we have made major progress in three general areas: (1) probed charge injection at the interface between a polymeric semiconductor and a polymer electrolyte dielectric and developed a thermodynamic model to quantitatively describe the transition from electrostatic to electrochemical doping; (2) developed vibrational Stark effect to probe electric field at buried organic semiconductor interfaces; (3) used displacement current measurement (DCM) to study charge transport at organic/dielectric interfaces and charge injection at metal/organic interfaces.

Zhu, Xiaoyang; Frisbie, C Daniel

2012-08-13T23:59:59.000Z

283

Growth and electrical characterisation of {delta}-doped boron layers on (111) diamond surfaces  

SciTech Connect

A plasma enhanced chemical vapor deposition protocol for the growth of {delta}-doping of boron in diamond is presented, using the (111) diamond plane as a substrate for diamond growth. AC Hall effect measurements have been performed on oxygen terminated {delta}-layers and desirable sheet carrier densities ({approx}10{sup 13} cm{sup -2}) for field-effect transistor application are reported with mobilities in excess of what would expected for equivalent but thicker heavily boron-doped diamond films. Temperature-dependent impedance spectroscopy and secondary ion mass spectroscopy measurements show that the grown layers have metallic-like electrical properties with high cut-off frequencies and low thermal impedance activation energies with estimated boron concentrations of approximately 10{sup 20} cm{sup -3}.

Edgington, Robert; Jackman, Richard B. [London Centre for Nanotechnology, and Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom); Sato, Syunsuke; Ishiyama, Yuichiro; Kawarada, Hiroshi [Department of Electronic and Photonic Systems, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Morris, Richard [Advanced SIMS Projects, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2012-02-01T23:59:59.000Z

284

Defect reaction network in Si-doped InP : numerical predictions.  

Science Conference Proceedings (OSTI)

This Report characterizes the defects in the defect reaction network in silicon-doped, n-type InP deduced from first principles density functional theory. The reaction network is deduced by following exothermic defect reactions starting with the initially mobile interstitial defects reacting with common displacement damage defects in Si-doped InP until culminating in immobile reaction products. The defect reactions and reaction energies are tabulated, along with the properties of all the silicon-related defects in the reaction network. This Report serves to extend the results for intrinsic defects in SAND 2012-3313: %E2%80%9CSimple intrinsic defects in InP: Numerical predictions%E2%80%9D to include Si-containing simple defects likely to be present in a radiation-induced defect reaction sequence.

Schultz, Peter Andrew

2013-10-01T23:59:59.000Z

285

Carrier Localization, Metal-Insulator Transitions and Stripe Formation in Inhomogeneous Hole-Doped Cuprates  

E-Print Network (OSTI)

We propose a unified approach for describing the carrier localization, metal-insulator transitions (MITs) and stripe formation in high-$T_c$ cuprates. The ground-state energy of a carrier interacting with a defect and with lattice vibrations is calculated within the continuum model and adiabatic approximation. At low doping levels, hole carriers in $\\rm{La}$-based systems with large-radius dopants are localized near the dopants with the formation of hydrogenic impurity centers.

S. Dzhumanov; O. K. Ganiev; Z. S. Khudayberdiev

2010-08-13T23:59:59.000Z

286

Phosphorus doping of 4H SiC by liquid immersion excimer laser irradiation  

SciTech Connect

Phosphorus doping of 4H SiC is performed by KrF excimer laser irradiation of 4H SiC immersed in phosphoric acid. Phosphorus is incorporated to a depth of a few tens of nanometers at a concentration of over 10{sup 20}/cm{sup 3} without generating significant crystal defects. Formation of a pn junction diode with an ideality factor of 1.06 is demonstrated.

Ikeda, Akihiro; Nishi, Koji; Ikenoue, Hiroshi; Asano, Tanemasa [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan)] [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan)

2013-02-04T23:59:59.000Z

287

Ion-assisted doping of 2-6 compounds during physical vapor deposition  

DOE Green Energy (OSTI)

This report describes a research program to (1) investigate ion-assisted doping during chemical vapor deposition of CdTe and (2) determine the influence of co-depositing ionized dopant atoms in the growth and structural and photoelectronic properties of the deposited films. In p-CdTe homo-epitaxial films, we controlled doping up to about 6 {times} 10{sup 16} cm{sup {minus}3} and 2 {times} 10{sup 17} cm{sub {minus}3} or ion-assisted depositions with As and P ions, respectively. At a growth rate of approximately 0.1 {mu}m/min, a substrate temperature of 400{degree}C, and ion energy of 60 eV, a maximum doping density was found near an ion current of 0.6{mu}A/cm{sup 2}. Related studies included elucidating the role of low-energy ion damage in the ion-assisted doping process, and investigating the decrease in carrier density near the surface of p-CdTe upon heating in vacuum, H{sub 2}, or Ar. We demonstrate the ability to make carrier density profiles and to grade junctions, and we present preliminary results from polycrystalline p-CdTe films grown on graphite and alumina substrates. We also present solar cells prepared using the p-CdTe as the collector area and n-CdS as the window layer, and we examine their photovoltaic parameters for different carrier densities and configurations in p-CdTe. 91 refs., 44 figs., 5 tabs.

Bube, R H [Stanford Univ., CA (USA). Dept. of Materials Science and Engineering

1990-07-01T23:59:59.000Z

288

Interaction of ? radiation with iron-doped n-type silicon  

Science Conference Proceedings (OSTI)

Deep-level transient spectroscopy (DLTS) measurements were carried out on low-doped n-silicon before and after irradiation with 5.48MeV @a particles at room temperature with a fluence of ~10^1^0@a particles/cm^2. The DLTS measurements on the samples ... Keywords: ?-Radiation, Deep-level defects, Deep-levels transient spectroscopy, Defects concentration

Khizar-ul-Haq; M. A. Khan; U. S. Qurashi; Abdul Majid

2008-05-01T23:59:59.000Z

289

Effect of organic salt doping on the performance of single layer bulk heterojunction organic solar cell  

Science Conference Proceedings (OSTI)

The effect of organic salt, tetrabutylammonium hexafluorophosphate (TBAPF{sub 6}) doping on the performance of single layer bulk heterojunction organic solar cell with ITO/MEHPPV:PCBM/Al structure was investigated where indium tin oxide (ITO) was used as anode, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) as donor, (6,6)-phenyl-C61 butyric acid methyl ester (PCBM) as acceptor and aluminium (Al) as cathode. In contrast to the undoped device, the electric field-treated device doped with TBAPF{sub 6} exhibited better solar cell performance under illumination with a halogen projector lamp at 100 mW/cm{sup 2}. The short circuit current density and the open circuit voltage of the doped device increased from 0.54 {mu}A/cm{sup 2} to 6.41 {mu}A/cm{sup 2} and from 0.24 V to 0.50 V, respectively as compared to those of the undoped device. The significant improvement was attributed to the increase of built-in electric field caused by accumulation of ionic species at the active layer/electrode interfaces. (author)

Yap, C.C.; Yahaya, M. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Salleh, M.M. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

2011-01-15T23:59:59.000Z

290

Formation of manganese {delta}-doped atomic layer in wurtzite GaN  

Science Conference Proceedings (OSTI)

We describe the formation of a {delta}-doped manganese layer embedded within c-plane wurtzite gallium nitride using a special molecular beam epitaxy growth process. Manganese is first deposited on the gallium-poor GaN (0001) surface, forming a {radical}(3) Multiplication-Sign {radical}(3)-R30 Degree-Sign reconstructed phase. This well-defined surface reconstruction is then nitrided using plasma nitridation, and gallium nitride is overgrown. The manganese content of the {radical}(3) Multiplication-Sign {radical}(3)-R30 Degree-Sign phase, namely one Mn per each {radical}(3) Multiplication-Sign {radical}(3)-R30 Degree-Sign unit cell, implies that the MnGaN alloy layer has a Mn concentration of up to 33%. The structure and chemical content of the surface are monitored beginning from the initial growth stage up through the overgrowth of 20 additional monolayers (MLs) of GaN. An exponential-like drop-off of the Mn signal with increasing GaN monolayers, as measured by Auger electron spectroscopy, indicates that the highly concentrated Mn layer remains at the {delta}-doped interface. A model of the resultant {delta}-doped structure is formulated based on the experimental data, and implications for possible spintronic applications are discussed.

Shi Meng; Chinchore, Abhijit; Wang Kangkang; Mandru, Andrada-Oana; Liu Yinghao; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States)

2012-09-01T23:59:59.000Z

291

Photo-degradation of methylene blue using Ta-doped ZnO nanoparticle  

SciTech Connect

A photocatalyst of Ta-doped ZnO was prepared by a modified Pechini-type method. The structural, morphological properties and photocatalytic activity of 1 mol % Ta-doped ZnO samples annealed at different temperatures were characterized. The photo-oxidation of methylene blue under the visible-light irradiation followed the pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. It is found that the photocatalysis of 1% Ta-doped ZnO annealed at 700 {sup o}C showed excellent performance of the photodegradation of methylene blue, which was attributed to a competitive trade-off among the crystallinity, surface hydroxyl groups, and specific surface area. The processing parameter such as the pH value also played an important role in tuning the photocatalytic activity. The maximum photodecomposed rate was achieved at pH=8, and an novel model about the absorption of methylene blue on the surface of the catalysts was proposed. - Graphical abstract: This model describes the adsorption between the amphoteric behavior of the metal oxide and the cationic dye methylene blue (MB) on the surface of the catalyst at the acidic and alkaline condition.

Kong Jizhou [National Laboratory of Solid State Microstructures, Materials Science and Engineering Department, Nanjing University, Nanjing 210093 (China); Li Aidong, E-mail: adli@nju.edu.c [National Laboratory of Solid State Microstructures, Materials Science and Engineering Department, Nanjing University, Nanjing 210093 (China); Li Xiangyu; Zhai Haifa; Zhang Wenqi; Gong Youpin; Li Hui; Wu Di [National Laboratory of Solid State Microstructures, Materials Science and Engineering Department, Nanjing University, Nanjing 210093 (China)

2010-06-15T23:59:59.000Z

292

Room temperature ferromagnetism in Mn, Ni and Co ions doped Cu{sub 2}O nanorods  

SciTech Connect

Here we report the synthesis and characterization of Cu{sub 2}O nanorods doped with Mn, Ni and Co transition metal ions and the study of their magnetic properties. Synthesis of the nanorods was carried out by the modified polyol method. Powder X-ray diffraction patterns clearly showed them to be polycrystalline single phase material. They exhibited ferromagnetic behavior at room temperature, however no such behavior was observed for the reference undoped sample, which indicated that unintentionally introduced magnetic impurities were not responsible for the observed phenomenon. Ferromagnetic behavior was found to be dependent on the dopant concentration and increased consistently with its increment in the material. The total magnetic moments contribution was calculated for the dopant concentration and was found to be insignificant to account for the observed ferromagnetism, therefore it was suggested that ferromagnetism could have conjured up from the induced magnetic moment in the defects created as cation vacancies in the material. The presence of the defects was supported by the room temperature photoluminescence study which showed that intensity of the peaks was dependent on the dopant concentration and increased consistently with it. There was strong correlation between the magnitude of the photoluminescence peak and the observed ferromagnetic property in the doped samples. -- Graphical Abstract: Room temperature ferromagnetism was observed in the Cu{sub 2}O nanorods doped with Mn, Ni and Co ions. The origin seems to be the defects of cation vacancies created by the dopant ions. Display Omitted

Ahmed, Asar [Department of Chemistry, SL-214, Southern Lab, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh (India); Gajbhiye, Namdeo S., E-mail: nsg@iitk.ac.i [Department of Chemistry, SL-214, Southern Lab, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh (India)

2010-12-15T23:59:59.000Z

293

Metallurgical and mechanical properties of thorium-doped Ir-0. 3% W alloys  

DOE Green Energy (OSTI)

Metallurgical and mechanical properties of Ir-0.3% W alloys have been studied as a function of thorium concentration in the range 0 to 1000 ppM by weight. The solubility limit of thorium in Ir-0.3% W is below 30 ppM. Above this limit, the excess thorium reacts with iridium to form second-phase particles. Thorium additions raise the recrystallization temperature and effectively retard grain growth at high temperatures. Tensile tests at 650/sup 0/C show that the alloy without thorium additions (undoped alloy) fractured by grainboundary (GB) separation, while the alloys doped with less than 500 ppM thorium failed mainly by transgranular fracture at 650/sup 0/C. Intergranular fracture in the doped alloys is suppressed by GB segregation of thorium, which improves the mechanical properties of the boundary. The impact properties of the alloys were correlated with test temperature, grain size, and heat treatment. The impact ductility increases with test temperature and decreases with grain size. For a given grain size, particularly in the fine-grain size range, the thorium-doped alloys are much more ductile and resistant to GB fracture. All of these results can be correlated on the basis of stress concentration on GBs by using a dislocation pileup model.

Liu, C.T.; Inouye, H.; Schaffhauser, A.C.

1980-04-01T23:59:59.000Z

294

Observation of green emission from Ce3+ doped gadolinium oxide nanoparticles  

SciTech Connect

Green emission at around 500 nm is observed in Gd2O3:Ce3+ nanoparticles and the intensity is highly dependent on the concentration of Ce3+ in the nanoparticles. The luminescence of this emission displays both picosecond and millisecond lifetimes. The msec lifetime is over four orders of magnitude longer than typical luminescence lifetimes (10-40 ns) of Ce3+ in traditional Ce3+ doped phosphors and therefore likely originates from defect states. The picosecond lifetime is shorter than the typical Ce3+ value and is also likely due to defect or surface states. When the samples are annealed at 700 oC, this emission disappears possibly due to changes in the defect moieties or concentration. In addition, a blue emission at around 430 nm is observed in freshly-prepared Gd2O3 undoped nanoparticles which is attributed to the stabilizer, polyethylene glycol biscarboxymethyl ether. Upon aging, the undoped particles show similar emission to the doped particles with similar luminescence lifetimes. When Eu3+ ions are co-doped in Gd2O3:Ce nanoparticles, both the green emission and the emission at 612 nm from Eu3+ are observed.

Woo, Boon K.; Joly, Alan G.; Chen, Wei

2011-01-01T23:59:59.000Z

295

Sodium-Doped Molybdenum Targets for Controllable Sodium Incorporation in CIGS Solar Cells: Preprint  

DOE Green Energy (OSTI)

The efficiency of Cu(In,Ga)Se2 (CIGS) solar cells is enhanced when Na is incorporated in the CIGS absorber layer. This work examines Na incorporation in CIGS utilizing Na-doped Mo sputtered from targets made with sodium molybdate-doped (MONA) powder. Mo:Na films with varying thicknesses were sputtered onto Mo-coated borosilicate glass (BSG) or stainless steel substrates for CIGS solar cells. By use of this technique, the Na content of CIGS can be varied from near-zero to higher than that obtained from a soda-lime glass (SLG) substrate. Targets and deposition conditions are described. The doped Mo films are analyzed, and the resulting devices are compared to devices fabricated on Mo-coated SLG as well as Mo-coated BSG with NaF. Completed devices utilizing MONA exceeded 15.7% efficiency without anti-reflective coating, which was consistently higher than devices prepared with the NaF precursor. Strategies for minimizing adhesion difficulties are presented.

Mansfield, L. M.; Repins, I. L.; Glynn, S.; Carducci, M. D.; Honecker, D. M.; Pankow, J.; Young, M.; DeHart, C.; Sundaramoorthy, R.; Beall, C. L.; To, B.

2011-07-01T23:59:59.000Z

296

Defect Levels of Indium-doped CdMnTe Crystals  

Science Conference Proceedings (OSTI)

Using photoluminescence (PL) and current deep-level transient spectroscopy (I-DLTS), we investigated the electronic defects of indium-doped detector-grade CdMnTe:In (CMT:In) crystals grown by the vertical Bridgman method. We similarly analyzed CdZnTe:In (CZT:In) and undoped CdMnTe (CMT) crystals grown under the amount of same level of excess Te and/or indium doping level to detail the fundamental properties of the electronic defect structure more readily. Extended defects, existing in all the samples, were revealed by synchrotron white beam x-ray diffraction topography and scanning electron microscopy. The electronic structure of CMT is very similar to that of CZT, with shallow traps, A-centers, Cd vacancies, deep levels, and Te antisites. The 1.1-eV deep level, revealed by PL in earlier studies of CZT and CdTe, were attributed to dislocation-induced defects. In our I-DLTS measurements, the 1.1-eV traps showed different activation energies with applied bias voltage and an exponential dependence on the trap-filling time, which are typical characteristics of dislocation-induced defects. We propose a new defect-trap model for indium-doped CMT crystals.

K Kim; A Bolotinikov; G Camarda; R Gul; A Hossain; G Yang; Y Cui; R James

2011-12-31T23:59:59.000Z

297

High-pressure structural phase transitions in chromium-doped BaFe2As2  

SciTech Connect

We report on the results from high pressure x-ray powder diffraction and electrical resistance measurements for hole doped BaFe{sub 2-x}Cr{sub x}As{sub 2} (x = 0, 0.05, 0.15, 0.4, 0.61) up to 81 GPa and down to 10 K using a synchrotron source and diamond anvil cell (DAC). At ambient temperature, an isostructural phase transition from a tetragonal (T) phase (I4/mmm) to a collapsed tetragonal (CT) phase is observed at 17 GPa. This transition is found to be dependent on ambient pressure unit cell volume and is slightly shifted to higher pressure upon increase in the Cr-doping. Unlike BaFe{sub 2}As{sub 2} which superconduct under high pressure, we have not detected any evidence of pressure induced superconductivity in chromium doped samples in the pressure and temperature range of this study. The measured equation of state parameters are presented for both the tetragonal and collapsed tetragonal phases for x = 0.05, 0.15, 0.40 and 0.61.

Uhoya, Walter [University of Alabama, Birmingham; Brill, Joseph W. [University of Kentucky; Montgomery, Jeffrey M [University of Alabama, Birmingham; Samudrala, G K [University of Alabama, Birmingham; Tsoi, Georgiy [University of Alabama, Birmingham; Vohra, Y. K. [University of Alabama, Birmingham; Weir, S. T. [Lawrence Livermore National Laboratory (LLNL); Safa-Sefat, Athena [ORNL

2012-01-01T23:59:59.000Z

298

Coulomb-oscillator origin of superconductivity in p-doped copper oxides  

E-Print Network (OSTI)

Emergence, development and cessation of superconductivity in three representative compounds of copper oxide families---cation doped Ca_2-xNa_xCuO2Cl2 and La_2-xAe_xCuO4 (Ae = Ba, Sr), as well as oxygen enriched YBa2Cu3O_6+x ---are explained with the Coulomb-oscillator model of superconductivity. By the model, non-resistive current is carried by axial Coulomb oscillations of s electrons through neighbor nuclei---here excited 3s electrons from O^2- ions through next-nearest neighbor oxygen nuclei---if their accompanying lateral oscillation is sufficiently confined to prevent lateral overswing. Cation doping gives rise to a superlattice in the layers that sandwich each CuO2 plane. In Ca_2-xNa_xCuO2Cl2, having one CuO2 plane per unit cell, superconductivity emerges when laterally confined Coulomb oscillators start connecting along 6 x 6 superlattice domains (in units of planar lattice constants) and it peaks at 4 x 4 domains when, at doping x = 1/8, the superlattice is completed. With further doping a new, off-set superlattice grows. Its frustrating effect gradually reduces superconductivity to cessation. The same mechanism holds for La_2-xAe_xCuO4 which has two, staggered CuO2 planes per unit cell. The staggering causes superconducting frustration or boost between adjacent layer sandwiches. This results in a double hump of the transition temperature Tc(x), instead of a dome, with a deep furrow or dip at x = 1/8 for Ae = Ba or Sr, respectively. Oxygen enrichment of YBa2Cu3O_6+x indirectly leads to effective doping in the CuO2 planes themselves (Cu^2+ --> Cu^3+). The ionization of copper ions at the corners of planar unit cells determines whether lateral oscillations between next-nearest neighbor O^2- ions overswing (Tc = 0) or are confined to wide or narrow electron tracks. Their percolating connectivity gives rise to respective plateaus of Tc = 57 K and Tc = 90 K, and intermediate ramps.

Manfred Bucher

2013-06-27T23:59:59.000Z

299

Electrical transport properties of the Si-doped cubic boron nitride thin films prepared by in situ cosputtering  

SciTech Connect

Si-doped cubic boron nitride (c-BN) films with various Si concentrations were achieved by in situ cosputtering during ion beam assisted deposition. Effects of the Si concentration and rapid thermal annealing (RTA) conditions on the electrical transport properties of Si-doped c-BN thin films were investigated systematically. The results suggest that the optimum RTA condition is at the temperature of 1000 deg. C for 3 min. The resistance of Si-doped c-BN films gradually decreases as the Si concentration increases, indicating an electrical doping effect of the Si impurity. The temperature dependent electrical conductivity of the Si-doped c-BN films suggests that different conduction mechanisms are dominant over the different temperature ranges. Based on the Davis-Mott model, we propose that the extended-state conduction, band tail-state conduction and short-range hopping conduction are responsible for the respective temperature ranges. In addition, the reduction in activation energy of Si impurities is observed as the Si concentration increases.

Ying, J.; Zhang, X. W.; Yin, Z. G.; Tan, H. R.; Zhang, S. G.; Fan, Y. M. [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2011-01-15T23:59:59.000Z

300

Infrared Measurement of the Pseudogap of P-Doped and Co-Doped High-Temperature BaFe2As2 Superconductors  

SciTech Connect

We report on infrared studies of charge dynamics in a prototypical pnictide system: the BaFe2As2 family. Our experiments have identified hallmarks of the pseudogap state in the BaFe2As2 system that mirror the spectroscopic manifestations of the pseudogap in the cuprates. The magnitude of the infrared pseudogap is in accord with that of the spin-density-wave gap of the parent compound. By monitoring the superconducting gap of both P- and Co-doped compounds, we find that the infrared pseudogap is unrelated to superconductivity. The appearance of the pseudogap is found to correlate with the evolution of the antiferromagnetic fluctuations associated with the spin-density-wave instability. The strong-coupling analysis of infrared data further reveals the interdependence between the magnetism and the pseudogap in the iron pnictides.

Moon, S.J.; Schafgans, A.A.; Kasahara, S.; Shibauchi, T.; Terashima, T.; Matsuda, Y.; Tanatar, Makariy A.; Prozorov, Ruslan; Thaler, Alexander; Canfield, Paul C.; Sefat, A.S.; Mandrus, D.; Basov, D.N.

2012-07-13T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


301

Lithium Doping of Single-Walled Carbon Nanotubes for Battery and Semiconductor Applications Kevin Donaher, Columbia University, Georgia Institute of Technology SURF 2010 Fellow  

E-Print Network (OSTI)

Lithium Doping of Single-Walled Carbon Nanotubes for Battery and Semiconductor Applications Kevin Jang, Mentor: Wonsang Koh Abstract The properties of lithium doped (5,5) metallic and (8 lithium binds to carbon nanotubes and how this affects the band structure of the semiconducting carbon

Li, Mo

302

Synthesis of Zr Doped NiO Layers on NiSi2 Linling Gu/Si-MCP Structures for Supercapacitors  

Science Conference Proceedings (OSTI)

Three-dimensional super capacitors consisting of NiSi2/silicon micro channel plates (MCPs) with Zr doped NiO layers have been fabricated. The silicon MCPs produced by electrochemical etching is utilized as a backbone of the 3D structure. Nickle layer ... Keywords: Zr doped NiO, Electrochemical properties, Silicon microchannel plate

Linling Gu; Tao Liu; Fei Wang; Shaohui Xu; Lianwei Wang; Paul K. Chu

2012-04-01T23:59:59.000Z

303

Ferromagnetism in Co-doped (La,Sr)TiO3  

SciTech Connect

The origin of ferromagnetism in Co-doped (La,Sr)TiO{sub 3} epitaxial thin films is discussed. While the as-grown samples are not ferromagnetic at room temperature or at 10 K, ferromagnetism at room temperature appears after annealing the films in reducing conditions and disappears after annealing in oxidizing conditions. Magnetic measurements, x-ray absorption spectroscopy, x-ray photoemission spectroscopy and transmission electron microscopy experiments indicate that within the resolution of the instruments the activation of the ferromagnetism is not due to the presence of pure Co.

Fix, T.; Liberati, M.; Aubriet, H.; Sahonta, S.-L.; Bali, R.; Becker, C.; Ruch, D.; MacManus-Driscoll, J.L.; Arenholz, E.; Blamire, M.G.

2009-04-21T23:59:59.000Z

304

Orbitronics: the Intrinsic Orbital Hall Effect in p-Doped Silicon  

SciTech Connect

The spin Hall effect depends crucially on the intrinsic spin-orbit coupling of the energy band. Because of the smaller spin-orbit coupling in silicon, the spin Hall effect is expected to be much reduced. We show that the electric field in p-doped silicon can induce a dissipationless orbital current in a fashion reminiscent of the spin Hall effect. The vertex correction due to impurity scattering vanishes and the effect is therefore robust against disorder. The orbital Hall effect can lead to the accumulation of local orbital momentum at the edge of the sample, and can be detected by the Kerr effect.

Bernevig, B.Andrei; Hughes, Taylor L.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-01-15T23:59:59.000Z

305

Doped, porous iron oxide films and their optical functions and anodic photocurrents for solar water splitting  

SciTech Connect

The fabrication and morphological, optical, and photoelectrochemical characterization of doped iron oxide films is presented. The complex index of refraction and absorption coefficient of polycrystalline films are determined through measurement and modeling of spectral transmission and reflection data using appropriate dispersion relations. Photoelectrochemical characterization for water photo-oxidation reveals that the conversion efficiencies of electrodes are strongly influenced by substrate temperature during their oblique-angle physical vapor deposition. These results are discussed in terms of the films' morphological features and the known optoelectronic limitations of iron oxide films for application in solar water splitting devices.

Kronawitter, Coleman X.; Mao, Samuel S. [Department of Mechanical Engineering, University of California at Berkeley, Berkeley, California 94720, USA and Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Antoun, Bonnie R. [Sandia National Laboratories, Livermore, California 94551 (United States)

2011-02-28T23:59:59.000Z

306

Electrically conductive doped block copolymer of polyacetylene and polyisoprene. [Soluble in organic solvents  

DOE Patents (OSTI)

An electrically conductive block copolymer of polyisoprene and polyacetylene and a method of making the same are disclosed. The polymer is prepared by first polymerizing isoprene with n-butyllithium in a toluene solution to form an active isoprenyllithium polymer. The active polymer is reacted with an equimolar amount of titanium butoxide and subsequently exposed to gaseous acetylene. A block copolymer of polyisoprene and polyacetylene is formed. The copolymer is soluble in common solvents and may be doped with I/sub 2/ to give it an electrical conductivity in the metallic regime.

Aldissi, M.

1984-06-27T23:59:59.000Z

307

Photovoltaic Device Including A Boron Doping Profile In An I-Type Layer  

DOE Patents (OSTI)

A photovoltaic cell for use in a single junction or multijunction photovoltaic device, which includes a p-type layer of a semiconductor compound including silicon, an i-type layer of an amorphous semiconductor compound including silicon, and an n-type layer of a semiconductor compound including silicon formed on the i-type layer. The i-type layer including an undoped first sublayer formed on the p-type layer, and a boron-doped second sublayer formed on the first sublayer.

Yang, Liyou (Lawrenceville, NJ)

1993-10-26T23:59:59.000Z

308

Manganese-doped indium oxide and its application in organic light-emitting diodes  

SciTech Connect

Thin films of manganese-doped indium oxide (IMO) deposited by electron beam evaporation have been investigated as anodes in organic light-emitting diodes (OLEDs). The IMO films have a high work function of 5.35 eV, a desirable surface morphology with an average roughness of 1.1 nm, a high average optical transmittance of 87.2% in the visible region, and a maximum optical transmittance of 92% at 460 nm. It is demonstrated that an IMO anode can effectively improve hole injection at the anode/organic interface, resulting in OLEDs with an increased electroluminescent efficiency.

Liao Yaqin [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Graduate School of Chinese Academy of Sciences, Beijing 100080 (China); Lu Qipeng; Fan Yi; Liu Xingyuan [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2011-07-11T23:59:59.000Z

309

Synthesis and characterization of Bi-doped Mg{sub 2}Si thermoelectric materials  

Science Conference Proceedings (OSTI)

The Mg{sub 2}Si-based alloys are promising candidates for thermoelectric energy conversion for the middle high range of temperature. They are very attractive as they could replace lead-based compounds due to their low cost and non toxicity. They could also result in thermoelectric generator weight reduction (a key feature for the automotive application field). The high value of thermal conductivity of the silicide-based materials could be reduced by increasing the phonon scattering in the presence of nanosized crystalline grains without heavily interfering with the electrical conductivity of the thermoelectric material. Nanostructured materials were obtained under inert atmosphere through ball milling, thermal treatment and spark plasma sintering processes. In particular, the role of several bismuth doping amounts in Mg{sub 2}Si were investigated (Mg{sub 2}Si:Bi=1:x for x=0.01, 0.02 and 0.04 M ratio). The morphology, the composition and the structure of the samples were characterized by FE-SEM, EDS and XRD analyses after each process step. Moreover, the Seebeck coefficient analyses at high temperature and the electrical and thermal conductivity of the samples are presented in this work. The nanostructuring processes were affect by the MgO amount increase which influenced the thermoelectric properties of the samples mainly by reducing the electrical conductivity. With the aim of further increasing the scattering phenomena by interface or boundary effect, carbon nanostructures named Single Wall Carbon Nanohorns were added to the Mg{sub 2}Si in order to produce a nanocomposite material. The influence of the nanostructured filler on the thermoelectric material properties is also discussed. - Graphical abstract: Figure of merit (ZT) of Bi-doped samples and undoped Mg{sub 2}Si. A maximum ZT value of 0.39 at 600 Degree-Sign C was obtained for the nanocomposite material obtained adding Single Wall Carbon Nanohorns to the Bi 0.02 at% doped silicide. Highlights: Black-Right-Pointing-Pointer Role of Bi doping amounts in Mg{sub 2}Si and thermoelectric characterization up to 600 Degree-Sign C Black-Right-Pointing-Pointer Nanocomposite materials synthesized by ball milling and Spark Plasma Sintering Black-Right-Pointing-Pointer Effect on scattering phenomena of Single Wall Carbon Nanohorns added to Mg{sub 2}Si Black-Right-Pointing-Pointer Importance of oxidation phenomena in nanostructured materials.

Fiameni, S., E-mail: s.fiameni@ieni.cnr.it [CNR - IENI, Corso Stati Uniti 4, 35127 Padova (Italy); Battiston, S.; Boldrini, S.; Famengo, A.; Agresti, F.; Barison, S.; Fabrizio, M. [CNR - IENI, Corso Stati Uniti 4, 35127 Padova (Italy)] [CNR - IENI, Corso Stati Uniti 4, 35127 Padova (Italy)

2012-09-15T23:59:59.000Z

310

Intrinsic Spin-Orbit Coupling in Superconducting Delta-Doped SrTiO3 Heterostructures  

SciTech Connect

We report the violation of the Pauli limit due to intrinsic spin-orbit coupling in SrTiO{sub 3} heterostructures. Via selective doping down to a few nanometers, a two-dimensional superconductor is formed, geometrically suppressing orbital pair-breaking. The spin-orbit scattering is exposed by the robust in-plane superconducting upper critical field, exceeding the Pauli limit by a factor of 4. Transport scattering times several orders of magnitude higher than for conventional thin film superconductors enables a new regime to be entered, where spin-orbit coupling effects arise non-perturbatively.

Bell, Christopher

2011-08-19T23:59:59.000Z

311

Free Volume Related Fluorescence Properties of Electron Irradiated Chalcone Doped PMMA Films  

Science Conference Proceedings (OSTI)

Effect of electron irradiation on free volume related fluorescence properties of chalcone doped Poly(methyl methacrylate)(PMMA) composite films have been studied using Positron Annihilation and Fluorescence spectroscopic techniques. In this polymer composite, enhancement of fluorescence at lower doses and reduction at higher doses has been observed under electron irradiation. From Positron annihilation studies suggests that at lower doses of irradiation induced crosslinking which affect the free volume properties and inturn hinders the chalcone molecular rotation. At higher doses chain scission process affect matrix relaxation. Under the restricted condition the chromophore molecules likely to emit enhanced fluorescence and its mobility is directly related to the free volume around it.

Ravindrachary, Ismayil V.; Bhajantri, R. F.; Harisha, A. [Department of Physics, Mangalore University, Mangalagangotri - 574 199 (India); Praveena, S. D. [Department of Physics, K.V.G College of Engineering, Kurunjibhag, Sullia, Karnataka - 574 327 (India)

2011-07-15T23:59:59.000Z

312

Iron-ceria Aerogels Doped with Palladium as Water-gas Shift Catalysts for the Production of Hydrogen  

Science Conference Proceedings (OSTI)

Mixed 4.5% iron oxide-95.5% cerium oxide aerogels doped with 1% and 2% palladium (Pd) by weight have been synthesized, and their activities for the catalysis of water-gas shift (WGS) reaction have been determined. The aerogels were synthesized using propylene oxide as the proton scavenger for the initiation of hydrolysis and polycondensation of a homogeneous alcoholic solution of cerium(III) chloride heptahydrate and iron(III) chloride hexahydrate precursor. Palladium was doped onto some of these materials by gas-phase incorporation (GPI) using ({eta}{sup 3}-allyl)({eta}{sup 5}-cyclopentadienyl)palladium as the volatile Pd precursor. Water-gas shift catalytic activities were evaluated in a six-channel fixed-bed reactor at atmospheric pressure and reaction temperatures ranging from 150 to 350 C. Both 1% and 2% Pd-doped 4.5% iron oxide-95.5% cerium oxide aerogels showed WGS activities that increased significantly from 150 to 350 C. The activities of 1% Pd-doped 4.5% iron oxide-95.5% cerium oxide aerogels were also compared with that of the 1% Pd-doped ceria aerogel without iron. The WGS activity of 1% Pd on 4.5% iron oxide-95.5% cerium oxide aerogels is substantially higher (5 times) than the activity of 1% Pd-doped ceria aerogel without iron. The gas-phase incorporation results in a better Pd dispersion. Ceria aerogel provides a nonrigid structure wherein iron is not significantly incorporated inside the matrix, thereby resulting in better contact between the Fe and Pd and thus enhancing the WGS activity. Further, neither Fe nor Pd is reduced during the ceria-aerogel-catalyzed WGS reaction. This behavior contrasts with that noted for other Fe-based WGS catalysts, in which the original ferric oxide is typically reduced to a nonstoichiometric magnetite form.

Bali, S.; Huggins, F; Ernst, R; Pugmire, R; Huffman, G; Eyring, E

2010-01-01T23:59:59.000Z

313

Zn-Doping Dependence of Stripe Order in La1.905Ba0.095CuO4  

Science Conference Proceedings (OSTI)

The effect of Zn-doping on the stripe order in La{sub 1.905}Ba{sub 0.095}CuO{sub 4} has been studied by means of x-ray and neutron diffraction as well as magnetization measurements. While 1% Zn leads to an increase of the spin stripe order, it unexpectedly causes a wipe out of the visibility of the charge stripe order. A magnetic field of 10 Tesla applied along the c-axis has no reversing effect on the charge order. We compare this observation with the Zn-doping dependence of the crystal structure, superconductivity, and normal state magnetism.

Hucker, M.; Zimmermann, M.v.; Xu, Z.J.; Wen, J.S.; Gu, G.D.; Tian, W.; Zarestky, J.; Tranquada, J.M.

2011-04-01T23:59:59.000Z

314

Energy Transfer Dynamics and Dopant Luminescence in Mn-Doped CdS/ZnS Core/Shell Nanocrystals  

E-Print Network (OSTI)

Mn-doped II-VI semiconductor nanocrystals exhibit bright dopant photoluminescence that has potential usefulness for light emitting devices, temperature sensing, and biological imaging. The bright luminescence comes from the 4T1?6A1 transition of the Mn2+ d electrons after the exciton-dopant energy transfer, which reroutes the exciton relaxation through trapping processes. The driving force of the energy transfer is the strong exchange coupling between the exciton and Mn2+ due to the confinement of exciton in the nanocrystal. The exciton-Mn spatial overlap affecting the exchange coupling strength is an important parameter that varies the energy transfer rate and the quantum yield of Mn luminescence. In this dissertation, this correlation is studied in radial doping location-controlled Mn-doped CdS/ZnS nanocrystals. Energy transfer rate was found decreasing when increasing the doping radius in the nanocrystals at the same core size and shell thickness and when increasing the size of the nanocrystals at a fixed doping radius. In addition to the exciton-Mn energy transfer discussed above, two consecutive exciton-Mn energy transfers can also occur if multiple excitons are generated before the relaxation of Mn (lifetime ~10^-4 - 10^-2 s). The consecutive exciton-Mn energy transfer can further excite the Mn2+ d electrons high in conduction band and results in the quenching of Mn luminescence. The highly excited electrons show higher photocatalytic efficiency than the electrons in undoped nanocrystals. Finally, the effect of local lattice strain on the local vibrational frequency and local thermal expansion was observed via the temperature-dependent Mn luminescence spectral linewidth and peak position in Mn-doped CdS/ZnS nanocrystals. The local lattice strain on the Mn2+ ions is varied using the large core/shell lattice mismatch (~7%) that creates a gradient of lattice strain at various radial locations. When doping the Mn2+ closer to the core/shell interface, the stronger lattice strain softens the vibrational frequency coupled to the 4T1?6A1 transition of Mn2+ (Mn luminescence) by ~50%. In addition, the lattice strain also increases the anharmonicity, resulting in larger local thermal expansion observed from the nearly an order larger thermal shift of the Mn luminescence compared to the Mn-doped ZnS nanocrystals without the core/shell lattice mismatch.

Chen, Hsiang-Yun

2012-12-01T23:59:59.000Z

315

Thermal stability of proton conducting acid doped polybenzimidazole in simulated fuel cell environments  

Science Conference Proceedings (OSTI)

Recently, polybenzimidazole membrane doped with phosphoric acid (PBI) was found to have promising properties for use as a polymer electrolyte in a high temperature (ca. 150 to 200 C) proton exchange membrane direct methanol fuel cell. However, operation at 200 C in strongly reducing and oxidizing environments introduces concerns of the thermal stability of the polymer electrolyte. To simulate the conditions in a high temperature fuel cell, PBI samples were loaded with fuel cell grade platinum black, doped with ca. 480 mole percent phosphoric acid (i.e., 4.8 H{sub 3}PO{sub 4} molecules per PBI repeat unit) and heated under atmospheres of either nitrogen, 5% hydrogen, or air in a thermal gravimetric analyzer. The products of decomposition were taken directly into a mass spectrometer for identification. In all cases weight loss below 400 C was found to be due to loss of water. Judging from the results of these tests, the thermal stability of PBI is more than adequate for use as a polymer electrolyte in a high temperature fuel cell.

Samms, S.R.; Wasmus, S.; Savinell, R.F. [Case Western Reserve Univ., Cleveland, OH (United States)

1996-04-01T23:59:59.000Z

316

Ferromagnetism in Doped Thin-Film Oxide and Nitride Semiconductors and Dielectrics  

SciTech Connect

The principal goal in the field of high-Tc ferromagnetic semiconductors is the synthesis, characterization and utilization of semiconductors which exhibit substantial carrier spin polarization at and above room temperature. Such materials are of critical importance in the emerging field of semiconductor spintronics. The interaction leading to carrier spin polarization, exchange coupling between the dopant spins and the valence or conduction band, is known to be sufficiently weak in conventional semiconductors, such as GaAs and Si, that magnetic ordering above cryogenic temperatures is essentially impossible. Since the provocative theoretical predictions of Tc above ambient in p-Mn:ZnO and p-Mn:GaN (T. Dietl et al., Science 287 1019 (2000)), and the observation of room-temperature ferromagnetism in Co:TiO2 anatase (Y. Matsumoto et al., Science 291 854 (2001)), there has been a flurry of work in oxides and nitrides doped with transition metals with unpaired d electrons. It has even been claimed that room-temperature ferromagnetism can be obtained in certain d0 transition metals oxides without a dopant. In this Report, the field of transition metal doped oxides and nitrides is critically reviewed and assessed from a materials science perspective. Since much of the field centers around thin film growth, this Report focuses on films prepared not only by conventional vacuum deposition methods, but also by spin coating colloidal nanoparticles.

Chambers, Scott A.

2006-10-01T23:59:59.000Z

317

One-Step Growth of Ge doped ZnO Tubes by Thermal Evaporation  

Science Conference Proceedings (OSTI)

In this paper we report a simple thermal evaporation technique (horizontal tube furnace) to grow the bulk-quantity of germanium (Ge) doped zinc oxide (ZnO) tubes on the Si substrate by using one-step thermal evaporation of a mixed powder of Ge and ZnO. The microstructure and optical properties of the Ge doped ZnO tubes have been investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction, photoluminescence (PL) spectrometer and Raman spectrometer. The investigation of structural properties indicated that the structures consist of bulk quantities of cylindrical rod and tube with diameter around 1micron. EDX reveals that the tube structures have Ge, Zn and O{sub 2} compositions and XRD analysis indicated the product is mainly composed of Ge, zinc germanium oxide (Zn{sub 2}GeO{sub 4}) and small proportion of ZnO. Room temperature photoluminescence (PL) spectrum shows broad emission peaks around 400 nm, opening up a route to potential applications in future optoelectronic devices. Raman measurement also measured at room temperature for these tubes.

Jumidali, M. M. [School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Penang (Malaysia); Faculty of Applied Science, Universiti Teknologi MARA, 13500 Penang (Malaysia); Hashim, M. R. [School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Penang (Malaysia); Sulieman, K. M. [Faculty of Applied Science, Universiti Teknologi MARA, 13500 Penang (Malaysia)

2011-03-30T23:59:59.000Z

318

Rapid Removal of Mercury from Aqueous Solutions Using Thiol Functionalized Zn-doped Biomagnetite Nanoparticles  

SciTech Connect

The surfaces of Zn-doped biomagnetite nanostructured particles were functionalized with (3-mercaptopropyl)trimethoxysilane (MPTMS) and used as a high-capacity and collectable adsorbent for the removal of Hg(II) from water. Fourier transform infrared spectroscopy (FTIR) confirmed the attachment of MPTMS on the particle surface. The crystallite size of the Zn-doped biomagnetite was {approx}17 nm, and the thickness of the MPTMS coating was {approx}5 nm. Scanning transmission electron microscopy and dynamic light scattering analyses revealed that the particles formed aggregates in aqueous solution with an average hydrodynamic size of 826 {+-} 32 nm. Elemental analyses indicate that the chemical composition of the biomagnetite is Zn{sub 0.46}Fe{sub 2.54}O{sub 4}, and the loading of sulfur is 3.6 mmol/g. The MPTMS-modified biomagnetite has a calculated saturation magnetization of 37.9 emu/g and can be separated from water within a minute using a magnet. Sorption of Hg(II) to the nanostructured particles was much faster than other commercial sorbents, and the Hg(II) sorption isotherm in an industrial wastewater follows the Langmuir model with a maximum capacity of {approx}416 mg/g, indicating two -SH groups bonded to one Hg. This new Hg(II) sorbent was stable in a range of solutions, from contaminated water to 0.5 M acid solutions, with low leaching of Fe, Zn, Si, and S (<10%).

He, Feng [ORNL; Wang, Wei [ORNL; Moon, Ji Won [ORNL; Howe, Jane Y [ORNL; Liang, Liyuan [ORNL; Pierce, Eric M [ORNL

2012-01-01T23:59:59.000Z

319

Jahn-Teller Effect and Superexchange in Half-Doped Manganites  

E-Print Network (OSTI)

We investigate the stability of the charge exchange (CE) phase within a microscopic model which describes a single plane as in La0.5Sr1.5MnO4. The model includes Coulomb interactions (on-site and intersite), the Jahn-Teller term and the superexchange interactions due to eg and t2g electrons. By investigating the phase diagram at T = 0 in mean-field approximation we conclude that the superexchange interactions can stabilize the CE phase, but only if they are stronger than estimated from spectroscopy. Journal reference: O. Sikora and A. M. Ole´s, Phys. Stat. Sol. (b) 236, 380 (2003). The doped manganites belong to a very interesting class of transition metal oxides, with orbital degrees of freedom and several magnetic phases stable in various doping regimes. The so-called charge exchange (CE) phase, composed of one-dimensional (1D) ferromagnetic (FM) zigzag chains with an antiferromagnetic (AF) coupling between them, has attracted a lot of attension recently, and the origin of its stability is still under debate [1]. The charge and orbital ordering sets in La0.5Ca0.5MnO3 at TCO ? 225 K, and is followed by a magnetic transition at TN ? 155 K [2]. The CE-phase was also observed in one-plane La0.5Sr1.5MnO4

Olga Sikora; Andrzej M. Ole´s

2002-01-01T23:59:59.000Z

320

Investigation of zinc oxide doped with metal impurities for use as thin film conductive phosphors  

E-Print Network (OSTI)

Various technologies for manufacturing flat panel displays are currently being pursued world-wide. These include active matrix LCD, passive matrix LCD, and LED technologies, as well as several field emission approaches. To facilitate the development of a viable flat panel display, low voltage, conductive phosphors which emit blue, red, and green light will be required for the field emission technology. This thesis examines zinc oxide (ZnO) based thin ( ) phosphors for such an application. ZnO is a 11-VI wide bandgap semiconductor which exhibits green luminescence and has been shown to produce red luminescence as well. However, no blue light emission from ZnO thin film phosphors has been reported. An experimental survey has been conducted in which metal dopants were introduced in ZnO. This survey has revealed tungsten doped ZnO to be a previously unreported brilliant blue phosphor with high resistivity. Additional experiments indicated aluminum could be introduced in conjunction with the tungsten to increase the conductivity of the new blue ZnO phosphors. ZnO doped samples with varying amounts of tungsten and aluminum were subsequently prepared and tested. Optimization of the annealing conditions was then studied. The survey results are contained herein. Finally, it should be noted these phosphors have produced light when used as the anode material in vacuum field emission diodes.

Evatt, Steven R.

1994-01-01T23:59:59.000Z

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321

Carriers-mediated ferromagnetic enhancement in Al-doped ZnMnO dilute magnetic semiconductors  

SciTech Connect

Nano-crystalline Zn{sub 0.95-x}Mn{sub 0.05}Al{sub x}O (x = 0, 0.05, 0.10) dilute magnetic semiconductors (DMS) were synthesized by sol-gel derived auto-combustion. X-ray diffraction (XRD) analysis shows that the samples have pure wurtzite structure typical of ZnO without the formation of secondary phases or impurity. Crystallite sizes were approximated by Scherrer formula while surface morphology and grain sizes were measured by field emission scanning electron microscopy. Incorporation of Mn and Al into the ZnO structure was confirmed by energy-dispersive X-ray analysis. Temperature dependent electrical resistivity measurements showed a decreasing trend with the doping of Al in ZnMnO, which is attributable to the enhancement of free carriers. Vibrating sample magnetometer studies confirmed the presence of ferromagnetic behavior at room temperature. The results indicate that Al doping results in significant variation in the concentration of free carriers and correspondingly the carrier-mediated magnetization and room temperature ferromagnetic behavior, showing promise for practical applications. We attribute the enhanced saturation magnetization and electrical conductivity to the exchange interaction mediated by free electrons.

Saleem, Murtaza [Centre of Excellence in Solid State Physics, University of the Punjab, Lahore-54590 (Pakistan); Siddiqi, Saadat A. [Centre of Excellence in Solid State Physics, University of the Punjab, Lahore-54590 (Pakistan); Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, Defence Road, Off Raiwind Road, Lahore (Pakistan); Atiq, Shahid, E-mail: shahidatiqpasrur@yahoo.com [Centre of Excellence in Solid State Physics, University of the Punjab, Lahore-54590 (Pakistan); Anwar, M. Sabieh; Hussain, Irshad [School of Science and Engineering (SSE), Lahore University of Management Sciences (LUMS), Opposite Sector U, D.H.A. Lahore Cantt-54792 (Pakistan); Alam, Shahzad [Pakistan Council for Scientific and Industrial Research (PCSIR) Laboratories Complex, Lahore (Pakistan)

2011-11-15T23:59:59.000Z

322

Lithium-sulfur batteries based on nitrogen-doped carbon and ionic liquid electrolyte  

Science Conference Proceedings (OSTI)

Nitrogen-doped mesoporous carbon (NC) and sulfur were used to prepare an NC/S composite cathode, which was evaluated in an ionic liquid electrolyte of 0.5 M lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in methylpropylpyrrolidinium bis(trifluoromethane sulfonyl)imide (MPPY.TFSI) by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cycle testing. To facilitate the comparison, a C/S composite based on activated carbon (AC) without nitrogen doping was also fabricated under the same conditions as those for the NC/S composite. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the early onset sulfur reduction potential, higher redox current density in the CV test, and faster charge transfer kinetics as indicated by EIS measurement. At room temperature under a current density of 84 mA g-1 (C/20), the battery based on the NC/S composite exhibited higher discharge potential and an initial capacity of 1420 mAh g-1 whereas that based on the AC/S composite showed lower discharge potential and an initial capacity of 1120 mAh g-1. Both batteries showed similar capacity fading with cycling due to the intrinsic polysulfide solubility and the polysulfide shuttle mechanism; the capacity fading can be improved by further modification of the cathode.

Sun, Xiao-Guang [ORNL; Wang, Xiqing [ORNL; Mayes, Richard T [ORNL; Dai, Sheng [ORNL

2012-01-01T23:59:59.000Z

323

Synthesis and optical properties of CsC1-doped gallium-sodium-sulfide glasses  

SciTech Connect

Ga{sub 2}S{sub 3}-Na{sub 2}S (GNS) glasses doped with CsCl were synthesized in open crucibles under inert atmosphere. The evaporative loss of CsCl during glass melting was measured by energy dispersive X-ray spectroscopy and corrected for by biasing the CsCl concentration in the mixture of starting materials to obtain glasses with accurately controlled stoichiometry. Glass transition temperatures, refractive index dispersions, and band edge energies were measured for four GNS:CsCl glasses, and the respective values were found to significantly improve over earlier studies that did not mitigate CsCl evaporative losses. The refractive index dispersion measurements indicate that the Cs{sup +} and Cl{sup -} radii are 16% larger in GNS:CsCl glass than in bulk crystalline CsCl. The band edge energy increases from 2.97 eV in GNS glass to 3.32 eV in GNS glass doped with 20 mol% CsCl as a result of introducing Cl{sup -} ions having a large optical electronegativity. The large bandgap of 3.32 eV and the low (450 cm{sup -1}) phonon energy make GNS:20%CsCl an attractive host material for rare-earth ions with radiative transitions in the near ultra-violet, visible, and near-infrared spectral regions.

Hehlen, Markus P [Los Alamos National Laboratory; Bennett, Bryan L [Los Alamos National Laboratory; Williams, Darrick J [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Castro, Alonso [Los Alamos National Laboratory; Tornga, Stephanie C [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

324

Evidence for a Lifshitz transition in electron-doped iron arsenic superconductors at the onset of superconductivity  

Science Conference Proceedings (OSTI)

The iron arsenic high-temperature superconductors exhibit particularly rich phase diagrams. In the AE(Fe{sub 1-x}T{sub x}){sub 2}As{sub 2} family (known as '122', with AE being Ca, Sr or Ba and T being a transition metal), the simultaneous structural/magnetic phase transition that occurs at elevated temperature in the undoped material splits and is suppressed by carrier doping. A superconducting region appears as likely in the orthorhombic/antiferromagnetic (AFM) state as in the tetragonal/paramagnetic state. An important question then is what determines the critical doping at which superconductivity emerges, as the AFM order is fully suppressed only close to optimal doping. Here we report evidence from angle-resolved photoemission spectroscopy that marked changes in the Fermi surface coincide with the onset of superconductivity in electron-doped Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2}. The presence of the AFM order leads to a reconstruction of the electronic structure, most significantly the appearance of the petal-like hole pockets at the Fermi level. These hole pockets vanish - that is, undergo a Lifshitz transition - as the cobalt concentration is increased sufficiently to support superconductivity. Superconductivity and magnetism are competing states in this system: when petal-like hole pockets are present, superconductivity is fully suppressed, whereas in their absence the two states can coexist.

Liu, Chang; Kondo, T.; Fernandes, R.M.; Palczewski, Ari D.; Mun, Eun Deok; Ni, Ni; Thaler, Alexander N.; Bostwick, Aaron; Rotenberg, Eli; Schmalian, Jorg; Bud-ko, Sergey L.; Canfield, Paul C.; and Kaminski, A.

2010-05-02T23:59:59.000Z

325

Transport in chemically doped graphene in the presence of adsorbed molecules E. H. Hwang, S. Adam, and S. Das Sarma  

E-Print Network (OSTI)

could be extremely high even at room temperature. The increase in graphene carrier mobility induced impurities.18 At high densities i.e., high gate voltages , one expects9 the competing effects of short Shown solid lines are the calculated graphene conductivity for both doped and undoped cases for ni =1

Adam, Shaffique

326

Absolute light yield measurements on SrF$_{2}$ and BaF$_{2}$ doped with rare earth ions  

E-Print Network (OSTI)

Results of absolute light output measurements on strontium and barium fluoride doped with PrF$_3$ and CeF$_3$ are presented and compared with scintillators having well-known light output (NaI-Tl, CsI-Tl, BGO). For pure SrF$_2$ crystal we obtain a value of about 28600 photons/MeV.

Shendrik, Roman

2013-01-01T23:59:59.000Z

327

Synthesis and characterization of sodium Bis(2-ethylhexyl) sulfonsuccinate (AOT) capped pure and Mn-doped CdS nanoparticles  

Science Conference Proceedings (OSTI)

CdS nanoparticles and thin films are well known for their excellent semiconducting properties. When transition metal ions are doped into the CdS, it exhibits magnetic properties in addition to semiconducting properties and they are termed as dilute magnetic ...

D. Venkatesan; D. Deepan; J. Ramkumar; S. Moorthy Babu; R. Dhanasekaran

2012-01-01T23:59:59.000Z

328

Octave-spanning supercontinuum generation for an er-doped fiber laser frequency comb at a 1 ghz repetition rate  

E-Print Network (OSTI)

We developed a 1 GHz Er-doped femtosecond fiber laser system providing 2nJ pulses at [equivalence relation symbol]100fs durations and demonstrated octave-spanning supercontinuum generation from 1µm - 2.4µm that is suitable ...

Chao, David

329

Doping Dependence of the $(\\pi,\\pi)$ Shadow Band in La-Based Cuprates Studied by Angle-Resolved Photoemission Spectroscopy  

SciTech Connect

The ({pi},{pi}) shadow band (SB) in La-based cuprate family (La214) was studied by angle-resolved photoemission spectroscopy (ARPES) over a wide doping range from x = 0.01 to x = 0.25. Unlike the well-studied case of the Bi-based cuprate family, an overall strong, monotonic doping dependence of the SB intensity at the Fermi level (E{sub F}) was observed. In contrast to a previous report for the presence of the SB only close to x = 1/8, we found it exists in a wide doping range, associated with a doping-independent ({pi},{pi}) wave vector but strongly doping-dependent intensity: It is the strongest at x {approx} 0.03 and systematically diminishes as the doping increases until it becomes negligible in the overdoped regime. This SB with the observed doping dependence of intensity can in principle be caused by the antiferromagnetic fluctuations or a particular form of low-temperature orthorhombic lattice distortion known to persist up to x {approx} 0.21 in the system, with both being weakened with increasing doping. However, a detailed binding energy dependent analysis of the SB at x = 0.07 does not appear to support the former interpretation, leaving the latter as a more plausible candidate, despite a challenge in quantitatively linking the doping dependences of the SB intensity and the magnitude of the lattice distortion. Our finding highlights the necessity of a careful and global consideration of the inherent structural complications for correctly understanding the cuprate Fermiology and its microscopic implication.

Shen, Z. X.

2011-08-15T23:59:59.000Z

330

Obtaining Mixed Ionic/Electronic Conductivity in Perovskite Oxides in a Reducing Environment: A Computational Prediction for Doped SrTiO3  

Science Conference Proceedings (OSTI)

The electronic conductivity and thermodynamic stability of mixed p- and n-doped SrTiO3 perovskites have been investigated under anodic solid oxide fuel cell conditions using density functional theory (DFT). In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability of various Ga- and La-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to determine the number of charge carriers and the degree of electronic conductivity. We find that a mixed ionic/electronic conductor can be obtained when doping SrTiO3 perovskite oxide with both p-type and n-type dopants. Calculations show that 10% Ga- and 20% La-doped SrTiO3 exhibit mixed ionic/electronic conductivity at high temperature and low oxygen partial pressure whereas doping with higher concentrations of Ga, e.g., 20%, diminishes the electronic conductivity of the material. Furthermore, changing the n-dopant from La (A-site) to Nb (B-site) does not significantly affect the reducibility and number of charge carriers in p- and n-doped SrTiO3. However, a higher degree of oxygen vacancy clustering is observed for the La-doped material which reduces the oxygen ion diffusion rate and traps electrons. Nevertheless, our findings suggest that independent of doping site, mixed ionic/ electronic conductivity can be obtained in SrTiO3 perovskite oxides under reducing conditions and high temperatures when using a mixed p- and n-type doping strategy that uses a p-dopant concentration smaller than the n-dopant concentration.

Suthirakun, Suwit; Ammal, Salai Cheettu; Xiao, Guoliang; Chen, Fanglin; Huang, Kevin; zur Loye, Hans-Conrad; Heyden, Andreas

2012-11-30T23:59:59.000Z

331

High Performance Ceramic Interconnect Material for Solid Oxide Fuel Cells (SOFCs): Ca- and Transition Metal-doped Yttrium Chromite  

Science Conference Proceedings (OSTI)

The effect of transition metal substitution on thermal and electrical properties of Ca-doped yttrium chromite was investigated in relation to use as a ceramic interconnect in high temperature solid oxide fuel cells (SOFCs). 10 at% Co, 4 at% Ni, and 1 at% Cu substitution on B-site of 20 at% Ca-doped yttrium chromite led to a close match of thermal expansion coefficient (TEC) with that of 8 mol% yttria-stabilized zirconia (YSZ), and a single phase Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 remained stable between 25 and 1100 degree C over a wide oxygen partial pressure range. Doping with Cu significantly facilitated densification of yttrium chromite. Ni dopant improved both electrical conductivity and dimensional stability in reducing environments, likely through diminishing the oxygen vacancy formation. Substitution with Co substantially enhanced electrical conductivity in oxidizing atmosphere, which was attributed to an increase in charge carrier density and hopping mobility. Electrical conductivity of Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 at 900 degree C is 57 S/cm in air and 11 S/cm in fuel (pO2=5×10^-17 atm) environments. Chemical compatibility of doped yttrium chromite with other cell components was verified at the processing temperatures. Based on the chemical and dimensional stability, sinterability, and thermal and electrical properties, Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 is suggested as a promising SOFC ceramic interconnect to potentially overcome technical limitations of conventional acceptor-doped lanthanum chromites.

Yoon, Kyung J.; Stevenson, Jeffry W.; Marina, Olga A.

2011-10-15T23:59:59.000Z

332

MA Doping Analysis on Breeding Capability and Protected Plutonium Production of Large FBR  

Science Conference Proceedings (OSTI)

Spent fuel from LWR can be seen as long-live waste if it is not recycled or as a 'new fuel' resource if it is recycled into the reactors. Uranium and plutonium have been used for 'new fuel' resources from LWR spent fuel as MOX fuel type which is loaded into thermal reactor or fast reactor types. Other actinides from the spent fuel such as neptunium, americium and curium as minor actinide (MA) are considered to be loaded into the reactors for specific purposes, recently. Those purposes such as for increasing protected plutonium production and breeding capability for protected plutonium as well as in the same time those amount of MA can be reduced to a small quantity as a burner or transmutation purpose. Some investigations and scientific approaches are performed in order to increase a material ''barrier'' in plutonium isotope composition by increasing the even mass number of plutonium isotope such as Pu-238, Pu-240 and Pu-242 as plutonium protected composition. Higher material barrier which related to intrinsic properties of plutonium isotopes with even mass number (Pu-238, Pu-240 and Pu-242), are recognized because of their intense decay heat (DH) and high spontaneous fission neutron (SFN) rates. Those even number mass of plutonium isotope contribute to some criteria of plutonium characterization which will be adopted for present study such as IAEA, Pellaud and Kessler criteria (IAEA, 1972; Pellaud, 2002; and Kessler, 2007). The present paper intends to evaluate the breeding capability as a fuel sustainability index of the reactors and to analyze the composition of protected plutonium production of large power reactor based on the FaCT FBR as reference (Ohki, et al., 2008). Three dimensional FBR core configuration has been adopted which is based on the core optimization calculation of SRAC-CITATION code as reactor core analysis and JENDL-3.3 is adopted for nuclear data library. Some MA doping materials are loaded into the blanket regions which can be considered as breeding region for protected plutonium production. Breeding capability of the reactor can be increased effectively by increasing MA doping rate while criticality condition of the reactor is reduced by doping MA. Adopting MA cycle is also effective to increase the isotopic Pu-238 production in plutonium vector composition for denaturing purpose of plutonium.

Permana, Sidik; Suzuki, Mitsutoshi; Kuno, Yusuke [Japan Atomic Energy Agency, Nuclear Non-proliferation Science and Technology Center, 2-4 Shirane Shirakata, Tokai-mura, Ibaraki, 319-1195 (Japan)

2010-06-22T23:59:59.000Z

333

Grain Growth Behavior, Tensile Impact Ductility, and Weldability of Cerium-Doped Iridium Alloys  

DOE Green Energy (OSTI)

An iridium alloy doped with small amounts of cerium and thorium is being developed as a potential replacement for the iridium-based DOP-26 alloy (doped with thorium only) that is currently used by the National Aeronautics and Space Administration (NASA) for cladding and post-impact containment of the radioactive fuel in radioisotope thermoelectric generator (RTG) heat sources which provide electric power for interplanetary spacecraft. This report summarizes results of studies conducted to date under the Iridium Alloy Characterization and Development subtask of the Radioisotope Power System Materials Production and Technology Program to characterize the properties of the iridium-based alloy (designated as DOP-40) containing both cerium and thorium. Included within this report are data on grain growth of sheet material in vacuum and low-pressure oxygen environments, grain growth in vacuum of the clad vent set cup material, weldability, and the effect of grain size and test temperature on tensile properties. Where applicable, data for the DOP-26 alloy are included for comparison. Both grain size and grain-boundary cohesion affect the ductility of iridium alloys. In this study it was found that cerium and thorium, when added together, refine grain size more effectively than when thorium is added by itself (especially at high temperatures). In addition, the effect of cerium additions on grain-boundary cohesion is similar to that of thorium. Mechanical testing at both low ({approx} 10{sup -3}s{sup -1}) and high ({approx} 10{sup -3}s{sup -1}) strain rates showed that the Ce/Th-doped alloys have tensile ductilities that are as good or better than the DOP-26 alloy. The general conclusion from these studies is that cerium can be used to replace some of the radioactive thorium currently used in DOP-26 while maintaining or improving its metallurgical properties. The current DOP-26 alloy meets all requirements for cladding the radioactive fuel in the RTG heat source, but the new DOP-40 alloy could serve as a back-up alloy to be used if the costs of refining, handling, and transporting DOP-26 become prohibitively high.

McKamey, C.G.

2002-05-28T23:59:59.000Z

334

Influence of encapsulation temperature on Ge:P {delta}-doped layers  

Science Conference Proceedings (OSTI)

We present a systematic study of the influence of the encapsulation temperature on dopant confinement and electrical properties of Ge:P {delta}-doped layers. For increasing growth temperature we observe an enhancement of the electrical properties accompanied by an increased segregation of the phosphorous donors, resulting in a slight broadening of the {delta} layer. We demonstrate that a step-flow growth achieved at {approx}530 deg. C provides the best compromise between high crystal quality and minimal dopant redistribution, with an electron mobility {approx}128 cm{sup 2}/Vs at a carrier density 1.3x10{sup 14} cm{sup -2}, and a 4.2 K phase coherence length of {approx}180 nm.

Scappucci, G.; Simmons, M. Y. [School of Physics and Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Capellini, G. [Dipartimento di Fisica, Universita di Roma Tre, Via della Vasca Navale 84, 00146 Roma (Italy)

2009-12-15T23:59:59.000Z

335

Extraction of the surface recombination velocity of passivated phosphorus-doped silicon emitters  

DOE Green Energy (OSTI)

An analytical procedure to extract the surface recombination velocity of the SiO{sub 2}/n type silicon interface, S{sub p}, from PCD measurements of emitter recombination currents is described. The analysis shows that the extracted values of S{sub p} are significantly affected by the assumed material parameters for highly doped silicon, t{sub p}, {mu}{sub p} and {Delta}E{sub g}{sup app}. Updated values for these parameters are used to obtain the dependence of S{sub p} on the phosphorus concentration, N{sub D}, using both previous and new experimental data. The new evidence supports the finding that S{sub p} increases strongly with N{sub D}.

Cuevas, A. [Australian National Univ., Canberra, CT (United States). Faculty of Engineering] [Australian National Univ., Canberra, CT (United States). Faculty of Engineering; Giroult-Matlakowski, G.; DuBols, C. [CNRS, Villeurbanne (France). Laboratoire de Physique de la Matiere] [CNRS, Villeurbanne (France). Laboratoire de Physique de la Matiere; Basore, P.A. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States); King, R.R. [Siemens Solar Industries, Camarillo, CA (United States)] [Siemens Solar Industries, Camarillo, CA (United States)

1995-01-01T23:59:59.000Z

336

Massive Dirac Fermion on the Surface of a Magnetically Doped Topological Insulator  

SciTech Connect

Topological insulators are characterized by a massless Dirac surface state and a bulk energy gap. An insulating massive Dirac fermion state is predicted to occur if the breaking of the time reversal symmetry opens an energy gap at the Dirac point, provided that the Fermi-energy resides inside both the surface and bulk gaps. By introducing magnetic dopants into the three dimensional topological insulator Bi{sub 2}Se{sub 3} to break the time reversal symmetry, we observed the formation of a massive Dirac fermion on the surface; simultaneous magnetic and charge doping furthermore positioned the Fermi-energy inside the Dirac gap. The insulating massive Dirac Fermion state thus obtained may provide a tool for studying a range of topological phenomena relevant to both condensed matter and particle physics.

Chen, Yulin

2011-05-20T23:59:59.000Z

337

Hf-Doped Ni-Al2O3 Interfaces at Equilibrium  

SciTech Connect

In this study, a series of dewetting experiments of pure and Hf-doped Ni films on sapphire and HfO2 substrates were conducted in order to measure the change in interface energy of the Ni-Al2O3 interface in the presence of Hf, and to study Hf interfacial segregation. It was found that Hf oxidizes under the conditions of the experiment (P(O2)=10-20atm.), and that the presence of HfO2 at the Ni-Al2O3 interface increases the interface energy from 2.16 0.2 to 2.7 0.4 [J/m2]. This result contradicts several theoretical studies that predict that Hf segregates to the interface to stabilize it thermodynamically. The solubility of Hf in bulk Ni was found to be significantly lower than the value reported in the equilibrium phase diagram.

Meltzman, Hila [Technion, Israel Institute of Technology; Besmann, Theodore M [ORNL; Kaplan, Prof. Wayne D. [Technion, Israel Institute of Technology

2012-01-01T23:59:59.000Z

338

Electric control of collective atomic coherence in an Erbium doped solid  

E-Print Network (OSTI)

We demonstrate fast and accurate control of the evolution of collective atomic coherences in an Erbium doped solid using external electric fields. This is achieved by controlling the inhomogeneous broadening of Erbium ions emitting at 1536 nm using an electric field gradient and the linear Stark effect. The manipulation of atomic coherence is characterized with the collective spontaneous emission (optical free induction decay) emitted by the sample after an optical excitation, which does not require any previous preparation of the atoms. We show that controlled dephasing and rephasing of the atoms by the electric field result in collapses and revivals of the optical free induction decay. Our results show that the use of external electric fields does not introduce any substantial additional decoherence and enables the manipulation of collective atomic coherence with a very high degree of precision on the time scale of tens of ns. This provides an interesting resource for photonic quantum state storage and quantum state manipulation.

Ji?í Miná?; Björn Lauritzen; Hugues de Riedmatten; Mikael Afzelius; Christoph Simon; Nicolas Gisin

2009-07-14T23:59:59.000Z

339

Inhomogeneous magnetism in the doped kagome lattice of LaCuO2.66  

Science Conference Proceedings (OSTI)

The hole-doped kagome lattice of Cu2+ ions in LaCuO2.66 was investigated by nuclear quadrupole resonance (NQR), electron spin resonance (ESR), electrical resistivity, bulk magnetization and specific heat measurements. For temperatures above 180 K, the spin and charge properties show an activated behavior suggestive of a narrow-gap semiconductor. At lower temperatures, the results indicate an insulating ground state which may or may not be charge ordered. While the frustrated spins in remaining patches of the original kagome lattice might not be directly detected here, the observation of coexisting non-magnetic sites, free spins and frozen moments reveals an intrinsically inhomogeneous magnetism. Numerical simulations of a 1/3-diluted kagome lattice rationalize this magnetic state in terms of a heterogeneous distribution of cluster sizes and morphologies near the site-percolation threshold.

Julien, M.-H. [Laboratoire National des Champs Magn´etiques Intenses; Simonet, V [Institut Neel, CNRS-UJF; Canals, B. [Institut Neel, CNRS-UJF; Garlea, Vasile O [ORNL; Bordet, Pierre [Laboratoire of Cristallographie, Grenoble; Darie, Celine [Laboratoire of Cristallographie, Grenoble

2013-01-01T23:59:59.000Z

340

Doping-Dependent Nodal Fermi Velocity in Bi-2212 Revealed by High-Resolution ARPES  

Science Conference Proceedings (OSTI)

The improved resolution of laser-based angle-resolved photoemission spectroscopy (ARPES) allows reliable access to fine structures in the spectrum. We present a systematic, doping-dependent study of a recently discovered low-energy kink in the nodal dispersion of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi-2212), which demonstrates the ubiquity and robustness of this kink in underdoped Bi-2212. The renormalization of the nodal velocity due to this kink becomes stronger with underdoping, revealing that the nodal Fermi velocity is non-universal, in contrast to assumed phenomenology. This is used together with laser-ARPES measurements of the gap velocity, v{sub 2}, to resolve discrepancies with thermal conductivity measurements.

Vishik, I. M.

2011-08-19T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


341

Evidence for charge Kondo effect in superconducting Tl-doped PbTe  

SciTech Connect

We report results of low-temperature thermodynamic and transport measurements of Pb{sub 1-x}Tl{sub x}Te single crystals for Tl concentrations up to the solubility limit of approximately x = 1.5%. For all doped samples, we observe a low-temperature resistivity upturn that scales in magnitude with the Tl concentration. The temperature and field dependence of this upturn are consistent with a charge Kondo effect involving degenerate Tl valence states differing by two electrons, with a characteristic Kondo temperature T{sub K} {approx} 6 K. The observation of such an effect supports an electronic pairing mechanism for superconductivity in this material and may account for the anomalously high T{sub c} values.

Fisher, I

2010-01-11T23:59:59.000Z

342

Strain effects on the ionic conductivity of Y-doped ceria: A simulation study  

E-Print Network (OSTI)

In this paper we report a computational study of the effects of strain on the conductivity of Y-doped ceria (YDC). This material was chosen as it is of technological interest in the field of Solid Oxide Fuel Cells (SOFCs). The simulations were performed under realistic operational temperatures and strain (\\epsilon) levels. For bulk and thin film YDC, the results show that tensile strain leads to conductivity enhancements of up to 3.5x and 1.44x, respectively. The magnitude of these enhancements is in agreement with recent experimental and computational evidence. In addition, the methods presented herein allowed us to identify enhanced ionic conductivity in the surface regions of YDC slabs and its anisotropic character.

Burbano, Mario; Watson, Graeme W

2013-01-01T23:59:59.000Z

343

Fabrication and Characterization of Dual Phase Magnesia-Zirconia Ceramics Doped with Plutonia  

Science Conference Proceedings (OSTI)

Dual phase magnesia-zirconia ceramics doped with plutonia are being studied as an inert matrix fuel (IMF) for light water reactors. The motivation of this work is to develop an IMF with a thermal conductivity superior to that of the fuels based on yttria stabilized zirconia. The concept uses the MgO phase as an efficient heat conductor to increase thermal conductivity of the composite. In this paper ceramic fabrication and characterization by scanning electron microscopy, energy and wavelength dispersive xray spectroscopy is discussed. Characterization shows that the ceramics consist of the two-phase matrix and PuO2-rich inclusions. The matrix is comprised of pure MgO phase and MgO-ZrO2-PuO2 solid solution. The PuO2-rich inclusion contained dissolved MgO and ZrO2.

P. G. Medvedev; J. F. Jue; S. M. Frank; M.K. Meyer

2005-05-01T23:59:59.000Z

344

Investigation of plasma-doped fin structure and characterization of dopants by atom probe tomography  

Science Conference Proceedings (OSTI)

As and P dopants in a plasma-doped Si-based fin structure were analyzed using atom probe tomography. The distributions and concentrations of As and P atoms in various regions of the fin structure and the oxidation levels for different dopants were determined. Most dopants were segregated at the fin boundary, and the As and P concentrations exceeded 9 Multiplication-Sign 10{sup 20} atoms/cm{sup 3} and 2 Multiplication-Sign 10{sup 20} atoms/cm{sup 3}, respectively. The atomic oxygen and SiO{sub 2} concentrations depended on the dopant type. The larger and heavier As dopant severely damaged the surface of the fin structure and could cause more severe oxidation.

Kim, B. H.; Park, S. M. [Department of Materials Science and Engineering, POSTECH, Pohang (Korea, Republic of); Park, S. W.; Park, Y. B.; Kim, H. J. [Research and Development Division, SK Hynix, 2091, Gyeongchung-daero, Bubal-eub, Ichon-si, Gyeonggi-do (Korea, Republic of); Park, C. G. [Department of Materials Science and Engineering, POSTECH, Pohang (Korea, Republic of); National Center for Nanomaterials Technology (NCNT), Pohang 790-784 (Korea, Republic of)

2012-11-19T23:59:59.000Z

345

Transport properties of InGaAs/GaAs Heterostructures with {delta}-doped quantum wells  

Science Conference Proceedings (OSTI)

The lateral transport of electrons in single- and double-well pseudomorphic GaAs/n-InGaAs/GaAs heterostructures with quantum wells 50-100 meV deep and impurity {delta}-layers in the wells, with concentrations in the range 10{sup 11} electron mobility with an increase in the impurity concentration. The results obtained indicate that the impurity-band electron states play an important role in the conductivity of these structures. Involvement of the impurity band also allows to explain adequately the characteristics of the conductivity of double-well structures; in contrast to single-well structures, band bending caused by asymmetric doping is of great importance. The numerical calculations of conductivity within the model under consideration confirm these suggestions.

Baidus, N. V. [Nizhni Novgorod State University, Physical-Technical Research Institute (Russian Federation); Vainberg, V. V. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine); Zvonkov, B. N. [Nizhni Novgorod State University, Physical-Technical Research Institute (Russian Federation); Pylypchuk, A. S., E-mail: pylypchuk@iop.kiev.ua; Poroshin, V. N.; Sarbey, O. G. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2012-05-15T23:59:59.000Z

346

Electronic Structure and Doping of P-Type Transparent Conducting Oxides: Preprint  

DOE Green Energy (OSTI)

Transparent conducting oxides (TCOs) are a group of materials that are widely used in solar cells and other optoelectronic devices. Recently, Cu-containing p-type TCOs such as MII Cu2 O2 (MIII=Mg, Ca, Sr, Ba) and CuMIII O2 (MIII=Al, Ga, In) have been proposed. Using first-principles band structure methods, we have systematically studied the electronic and optical properties of these p-type transparent oxides. For MII Cu2 O2 , we predict that adding a small amount of Ca into Sr Cu2 O2 can increase the transparency and conductivity. For CuMIII O2 , we explained the doping and band gap anomalies in this system and proposed a new approach to search for bipolar dopable wide-gap materials.

Wei, S.-H.; Nie, X.; Zhang, S. B.

2002-05-01T23:59:59.000Z

347

Transcription of domain patterns in near-stoichiometric magnesium-doped lithium niobate  

SciTech Connect

Recently, light-induced domain reversal has been developed to a promising method for domain engineering, but the depth of reversed domain is only of several tens of microns, which greatly limits its practical applications. In this Letter, we fabricated domain patterns on the -z face of 1.0 mol % Mg doped near-stoichiometric lithium niobate with the assistance of a focal 532 nm laser, and then succeeded to transcribe these domain patterns from the -z to the +z face by applying external field without laser illumination. The transcribed domains have much larger depths, can sustain more than 100 times of the transcription cycles without large deformation, and can be erased by one transcription cycle with illumination of 532 nm laser. Finally, a light-induced ferroelectric domain transcription model was proposed.

Zeng Hao; Tian Tian; Sun Tongqing [School of Physics, Nankai University, Tianjin 300071 (China); Kong Yongfa; Chen Shaolin; Zhang Ling; Rupp, Romano [MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Xu Jingjun [School of Physics, Nankai University, Tianjin 300071 (China); MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China)

2010-11-15T23:59:59.000Z

348

Direct Observation of sp-d Exchange Interactions in Colloidal Mn2+- and Co2+-Doped CdSe Quantum Dots  

SciTech Connect

The defining attribute of a diluted magnetic semiconductor (DMS) is the existence of dopant-carrier magnetic exchange interactions. In this letter, we report the first direct observation of such exchange interactions in colloidal doped CdSe nanocrystals. Doped CdSe quantum dots were synthesized by thermal decomposition of (Me4N)2[Cd4(SePh)10] in the presence of TMCl2 (TM2+ ) Mn2+ or Co2+) in hexadecylamine and were characterized by several analytical and spectroscopic techniques. Using magnetic circular dichroism spectroscopy, successful doping and the existence of giant excitonic Zeeman splittings in both Mn2+- and Co2+-doped wurtzite CdSe quantum dots are demonstrated unambiguously.

Archer, Paul I.; Santangelo, Steven A.; Gamelin, Daniel R.

2007-03-23T23:59:59.000Z

349

Comparative study of InGaP/GaAs high electron mobility transistors with upper and lower delta-doped supplied layers  

Science Conference Proceedings (OSTI)

Influence corresponding to the position of {delta}-doped supplied layer on InGaP/GaAs high electron mobility transistors is comparatively studied by two-dimensional simulation analysis. The simulated results exhibit that the device with lower {delta}-doped supplied layer shows a higher gate potential barrier height, a higher saturation output current, a larger magnitude of negative threshold voltage, and broader gate voltage swing, as compared to the device with upper {delta}-doped supplied layer. Nevertheless, it has smaller transconductance and inferior high-frequency characteristics in the device with lower {delta}-doped supplied layer. Furthermore, a knee effect in current-voltage curves is observed at low drain-to-source voltage in the two devices, which is investigated in this article.

Tsai, Jung-Hui, E-mail: jhtsai@nknucc.nknu.edu.tw; Ye, Sheng-Shiun [National Kaohsiung Normal University, Department of Electronic Engineering, Taiwan (China); Guo, Der-Feng [Air Force Academy, Kaohsiung, Department of Electronic Engineering, Taiwan (China); Lour, Wen-Shiung [National Taiwan Ocean University, Department of Electrical Engineering, Taiwan (China)

2012-04-15T23:59:59.000Z

350

Examination of Na-Doped Mo Sputtering for CIGS Devices: Cooperative Research and Development Final Report, CRADA Number CRD-10-375  

DOE Green Energy (OSTI)

This work has investigated the use of Na doped Mo (MONA) sputtering targets for use in preparing CIGS devices. The Mo:Na material is doped to about 3% Na by weight, implying that a 40 nm layer on top of the standard Mo contact contains sufficient Na to dope a 2.5 ..mu..m CIGS film. The ability to control Na doping independent of both CIGS processing conditions and adhesion is an important gain for industry and research. Manufacturers gain a route to increased manufacturability and performance, while NREL researchers gain a tightened performance distribution of devices and increased process flexibility. Our immediate partner in this work, the Climax Molybdenum Technology Center, gains validation of their product.

Repins, I.

2012-01-01T23:59:59.000Z

351

Normal-state transport in electron-doped La2-xCexCuO4 thin films in magnetic fields up to 40 Tesla  

E-Print Network (OSTI)

Normal-state transport in electron-doped La2-xCexCuO4 thin films in magnetic fields up to 40 Tesla.17 are studied in magnetic fields up to 40 Tesla. For the whole doping region investigated, the negative, the upper critical mag- netic field Bc2 order of 100 Tesla 8 is too high to be achieved. The n-type HTSCs

Moshchalkov, Victor V.

352

Theoretical prediction of the plasma frequency and Moss-Burstein shifts for degenerately doped In{sub x}Ga{sub 1{minus}x}As  

DOE Green Energy (OSTI)

Theoretical predictions for the plasma frequency and Moss-Burstein shift (optical band gap) of degenerately doped (n > 10{sup 19} cm{sup {minus}3}) In{sub x}Ga{sub 1{minus}x} As are presented. This system is of interest because it possesses desirable optical properties for thermophotovoltaic (TPV) applications. The studies presented are based on electronic band structures calculated using the Full Potential Linearized Augmented Plane Wave (FLAPW) method which includes non-local screened exchange (sX-LDA) and spin-orbit effects. The plasma frequency and Moss-Burstein shift are calculated vs. doping assuming a rigid band approximation (i.e. conduction band filling of the undoped bands). The doping dependence of the effective mass (band non-parabolicity) plays an important role at the high dopings considered here. This effect leads to a maximum in the plasma frequency vs. doping (2--3 {times} 10{sup 14}/s) and a significant departure from the constant effective mass prediction for the optical band gap vs. doping. These calculations are in good agreement with measurements.

Raynolds, J.E.; Charache, G.W. [Lockheed Martin Corp., Schenectady, NY (United States); Geller, C.B. [Bettis Atomic Power Lab., West Mifflin, PA (United States); Holden, T.; Pollak, F.H. [City Univ. of New York, Brooklyn, NY (United States)

1998-10-01T23:59:59.000Z

353

Defect processes involving oxygen-compensated sites in CaF/sub 2/ precipitates doped with lanthanides and actinides  

Science Conference Proceedings (OSTI)

Oxygen incorporation into calcium fluoride precipitates doped with lanthanides and actinides is investigated by use of the technique of site-selective spectroscopy. Fluorescence from erbium in specific fluoride- and oxygen-compensated sites is monitored as a function of the ignition temperature of the precipitate to study the conversion from fluoride to oxygen compensation. Another process, thermal annealing of a disordered precipitate to give a well-defined lattice, is also followed. Changes in both oxygen compensation formation and lattice annealing are found to occur upon the addition of other trivalent and monovalent ions. The results provide a better understanding of the solid-state chemistry involved in new methods of chemical analysis using rare-earth doped CaF/sub 2/ precipitates, and how certain interference effects can arise. Also included is a study of the temperature dependence of fluorescent sites in CaF/sub 2/:U/sup 6 +/.

Johnston, M.V.; Wright, J.C.

1981-10-15T23:59:59.000Z

354

ASNOM mapping of SiC epi-layer doping profile and of surface phonon polariton waveguiding  

E-Print Network (OSTI)

The apertureless SNOM mapping of the slightly-doped 4H-SiC epitaxial layer grown on a heavily-doped 4H-SiC substrate was performed with a cleaved edge geometry. ASNOM images taken at the light frequencies of a $C^{13}O_{2}^{16}$ laser show a clear contrast between the substrate and the epitaxial layer. The contrast vanishes at the laser frequency of $884cm^{-1}$, and gets clearer at higher frequencies $(923cm^{-1})$. This can be explained by changes in the local polarizability of SiC caused by the carrier concentration, which are more pronounced at higher frequencies. Since the light frequency is tuned up further ($935cm^{-1}$), a transversal mode structure appears in the ASNOM map, indicating a waveguide-like confinement of a surface phonon polariton wave inside the strip of an epi-layer outcrop.

Kazantsev, Dmitry

2013-01-01T23:59:59.000Z

355

N-polar III-nitride quantum well light-emitting diodes with polarization-induced doping  

Science Conference Proceedings (OSTI)

Nitrogen-polar III-nitride heterostructures present unexplored advantages over Ga(metal)-polar crystals for optoelectronic devices. This work reports N-polar III-nitride quantum-well ultraviolet light-emitting diodes grown by plasma-assisted molecular beam epitaxy that integrate polarization-induced p-type doping by compositional grading from GaN to AlGaN along N-face. The graded AlGaN layer simultaneously acts as an electron blocking layer while facilitating smooth injection of holes into the active region, while the built-in electric field in the barriers improves carrier injection into quantum wells. The enhanced doping, carrier injection, and light extraction indicate that N-polar structures have the potential to exceed the performance of metal-polar ultraviolet light-emitting diodes.

Verma, Jai; Simon, John; Protasenko, Vladimir; Kosel, Thomas; Xing, Huili Grace; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

2011-10-24T23:59:59.000Z

356

Luminescence Spectroscopy of Eu-doped (Ca,Sr)TiO{sub 3} Nanocrystals Prepared by Using Sonochemical Method  

Science Conference Proceedings (OSTI)

Perovskite-type compounds (ABO{sub 3}) of (Ca,Sr)TiO{sub 3} doped with trivalent europium (Eu{sup 3+}) were synthesized by sonochemical techniques. Powder X-ray diffraction measurement on (Ca,Sr)TiO{sub 3} were used to identify the perovskite crystal structure. The photoluminescence property in (Ca,Sr)TiO{sub 3} with europium substitution several atoms in the host lattice was also studied. Further, the photoluminescence spectra were taken at room temperature. The structural difference between fourth kinds of doped samples with different heating temperatures accounts for the intensification of the luminescence intensity. The presented measurements monitor the emission wavelengths of the Eu{sup 3+} with emission peaks at 593, 615 and 700 nm. The obtained results were discussed with respect to developed preparation method.

Kurniawan, C. [Chemistry Department of Semarang State University, Jl. Raya Sekaran Semarang (Indonesia); Prijamboedi, B. [Chemistry Department of Bandung Institute of Technology, Jl. Ganesha 10 Bandung (Indonesia)

2010-10-24T23:59:59.000Z

357

X-ray photoelectron spectroscopy studies on Pd doped SnO{sub 2} liquid petroleum gas sensor  

Science Conference Proceedings (OSTI)

The present investigation deals with the electrical response of palladium doped tin oxide, as a means of improving the selectivity for liquid petroleum gas (LPG) in the presence of CO, CH{sub 4}. The sensor element with the composition of Pd(1.5 wt{percent}) in the base material SnO{sub 2} sintered at 800{degree}C, has shown a high sensitivity towards LPG with a negligible cross interference of CO and CH{sub 4} at an operating temperature of 350{degree}C. This greatly suggests the possibility of utilizing the sensor for the detection of LPG. X-ray photoelectron spectroscopy studies have been carried out to determine the possible chemical species involved in the gas-solid interaction and the enhancing mechanism of the Pd doped SnO{sub 2} sensor element, towards LPG sensitivity. {copyright} {ital 1997 American Institute of Physics.}

Phani, A.R. [Department of Physics, University of LAquila, 67040, LAquila (Italy)

1997-10-01T23:59:59.000Z

358

p-type conduction induced by N-doping in {alpha}-Fe{sub 2}O{sub 3}  

Science Conference Proceedings (OSTI)

A p-type N-doped {alpha}-Fe{sub 2}O{sub 3} was developed by magnetron sputtering of a Fe{sub 2}O{sub 3} target in a plasma containing N{sub 2} and Ar followed by postannealing. Photoelectrochemical measurement under visible light irradiation (>410 nm) showed that N-Fe{sub 2}O{sub 3} exhibits a typical cathodic photocurrent originated from the p-type conduction. X-ray photoemission spectroscopy indicated that the atomic N incorporated substitutionally at O sites was responsible for the p-type conduction. The concentration of acceptors was very close to that for Zn-doped Fe{sub 2}O{sub 3}, a typical p-type {alpha}-Fe{sub 2}O{sub 3}. This finding would stimulate further research on p-type Fe{sub 2}O{sub 3} for solar fuel generation, etc.

Morikawa, Takeshi; Kitazumi, Kousuke; Takahashi, Naoko; Arai, Takeo; Kajino, Tsutomu [Toyota Central Research and Development Laboratories, Inc., Nagakute, Aichi 480-1192 (Japan)

2011-06-13T23:59:59.000Z

359

Thermal lens study of thermo-optical properties and concentration quenching of Er3+-doped lead pyrophosphate based glasses  

Science Conference Proceedings (OSTI)

In this work, we have used the thermal lens technique combined with conventional spectroscopy to characterize the thermo-optical properties of Er3+-doped lead pyrophosphate-based glasses. More precisely, we have investigated and quantified experimentally the fluorescence quantum efficiencies of the Er3+ levels, and we describe the role of concentration quenching effects. The fluorescence quantum efficiency of the 4I13/2 level is very high when compared to other phosphate glasses, while that of the green-coupled levels is very small. Other important photonic materials parameters, such as the thermal diffusivity and temperature coefficient of the optical path length change, were obtained and compared with those of other glass systems. The cumulative results obtained here for the Er-doped lead pyrophosphate glass show that this material is a good candidate for photonic applications with a characteristic Er3+ infrared emission around 1550 nm.

Santos, C. C. [Universidade Federal do Ceara, Ceara, Brazil; Rocha, U. [Grupo de Fotônica e Fluidos Complexos, Instituto de Física, Brazil; Guedes, Ilde [Universidade Federal do Ceara, Ceara, Brazil; Vermelho, M. V. D. [Instituto de Fisica, Universidade Federal de Alagoas, Brazil; Boatner, Lynn A [ORNL; Jacinto, C. [Instituto de Fisica, Universidade Federal de Alagoas, Brazil

2012-01-01T23:59:59.000Z

360

Performance improvement of Ge-Sb-Te material by GaSb doping for phase change memory  

SciTech Connect

Effects of GaSb doping on phase change characteristics of Ge-Sb-Te material are investigated by in situ resistance and x-ray diffraction measurement, optical spectroscopy, and x-ray photoelectron spectroscopy. The crystallization temperature and data retention of Ge-Sb-Te material increase significantly by the addition of GaSb, which results from the high thermal stability of amorphous GaSb. In addition, GaSb-doped Ge-Sb-Te material exhibits faster crystallization speed due to the change in electronic states as a result of the formation of chemical bonds with Ga element. Incorporation of GaSb is highly effective way to enhance the comprehensive performance of Ge-Sb-Te material for phase change memory.

Lu, Yegang [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China) [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Zhonghua; Song, Sannian; Cheng, Limin; Song, Zhitang [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)] [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Shen, Xiang; Wang, Guoxiang; Dai, Shixun [Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211 (China)] [Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211 (China)

2013-06-17T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Double pulse doped InGaAs/AlGaAs/GaAs pseudomorphic high-electron-mobility transistor heterostructures  

Science Conference Proceedings (OSTI)

Double pulse doped ({delta}-doped) InGaAs/AlGaAs/GaAs pseudomorphic high-electron-mobility transistor (HEMT) heterostructures were grown by molecular-beam epitaxy using a multiwafer technological system. The room-temperature electron mobility was determined by the Hall method as 6550 and 6000 cm{sup 2}/(V s) at sheet electron densities of 3.00 x 10{sup 12} and 3.36 x 10{sup 12} cm{sup -2}, respectively. HEMT heterostructures fabricated in a single process feature high uniformity of structural and electrical characteristics over the entire area of wafers 76.2 mm in diameter and high reproducibility of characteristics from process to process.

Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Gladyshev, A. G.; Nikitina, E. V.; Denisov, D. V.; Polyakov, N. K.; Pirogov, E. V.; Gorbazevich, A. A. [Russian Academy of Sciences, St. Petersburg Physics and Technology Center for Research and Education (Russian Federation)

2010-07-15T23:59:59.000Z

362

Transparent conducting impurity-doped ZnO thin films prepared using oxide targets sintered by millimeter-wave heating  

Science Conference Proceedings (OSTI)

The preparation of transparent conducting impurity-doped ZnO thin films by both pulsed laser deposition (PLD) and magnetron sputtering deposition (MSD) using impurity-doped ZnO targets sintered with a newly developed energy saving millimeter-wave (28 GHz) heating technique is described. Al-doped ZnO (AZO) and V-co-doped AZO (AZO:V) targets were prepared by sintering with various impurity contents for 30 min at a temperature of approximately 1250 degree sign C in an air or Ar gas atmosphere using the millimeter-wave heating technique. The resulting resistivity and its thickness dependence obtainable in thin films prepared by PLD using millimeter-wave-sintered AZO targets were comparable to those obtained in thin films prepared by PLD using conventional furnace-sintered AZO targets; a low resistivity on the order of 3x10{sup -4} {Omega} cm was obtained in AZO thin films prepared with an Al content [Al/(Al+Zn) atomic ratio] of 3.2 at. % and a thickness of 100 nm. In addition, the resulting resistivity and its spatial distribution on the substrate surface obtainable in thin films prepared by rf-MSD using a millimeter-wave-sintered AZO target were almost the same as those obtained in thin films prepared by rf-MSD using a conventional powder AZO target. Thin films prepared by PLD using millimeter-wave-sintered AZO:V targets exhibited an improved resistivity stability in a high humidity environment. Thin films deposited with a thickness of approximately 100 nm using an AZO:V target codoped with an Al content of 4 at. % and a V content [V/(V+Zn) atomic ratio] of 0.2 at. % were sufficiently stable when long-term tested in air at 90% relative humidity and 60 degree sign C.

Minami, Tadatsugu; Okada, Kenji; Miyata, Toshihiro; Nomoto, Juni-chi; Hara, Youhei; Abe, Hiroshi [Optoelectronic Device System R and D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501 (Japan); Fuji Dempa Kogyo Co. Ltd., 26 Kasuminosato, Ami, Inashiki, Ibaragi 300-0315 (Japan)

2009-07-15T23:59:59.000Z

363

The effects of silicon doping on the performance of PMAN carbon anodes in Li-ion cells  

DOE Green Energy (OSTI)

Carbons derived from polymethylacrylonitrile (PMAN) have been studied for use as intercalation anodes in Li-ion cells. The effect of Si doping upon the electrochemical performance of PMAN carbons was studied using tetravinylsilane (TVS) and tetramethysilane (TMS) as sources of Si during the formation of the PMAN precursors. The carbons were characterized by galvanostatic cycling, cyclic voltammetry, and complex impedance. The presence of 9 to 11 w/o Si in the PMAN lattice greatly increased the irreversible capacity of these materials.

Guidotti, R.A.; Johnson, B.J. [Sandia National Labs., Albuquerque, NM (United States); Even, W. Jr. [Sandia National Labs., Livermore, CA (United States)

1996-05-01T23:59:59.000Z

364

Effective hole-injection layer for non-doped inverted top-emitting organic light-emitting devices  

Science Conference Proceedings (OSTI)

Non-doped inverted top-emitting organic light-emitting diode with high efficiency is demonstrated through employing an effective hole-injection layer composed of MoO"x. One reason for high efficiency lies on the energy-level matching between MoO"x and ... Keywords: 78.60.Fi, 82.45.Mp, 85.60.Jb, Hole-injection, ITEOLEDs, MoOx

Yanlong Meng; Wenfa Xie; Ning Zhang; Shufen Chen; Jiang Li; Wei Hu; Yi Zhao; Jingying Hou; Shiyong Liu

2008-05-01T23:59:59.000Z

365

Electron-donor dopant, method of improving conductivity of polymers by doping therewith, and a polymer so treated  

DOE Patents (OSTI)

Polymers with conjugated backbones, both polyacetylene and polyaromatic heterocyclic types, are doped with electron-donor agents to increase their electrical conductivity. The electron-donor agents are either electride dopants made in the presence of lithium or dopants derived from alkalides made in the presence of lithium. The dopants also contain a metal such as cesium and a trapping agent such as a crown ether.

Liepins, R.; Aldissi, M.

1984-07-27T23:59:59.000Z

366

Specific Heat Measurements and Post-Test Characterization of Irradiated and Unirradiated Urania and Gadolinia Doped Fuel  

Science Conference Proceedings (OSTI)

In pursuit of higher burnups at nuclear plants, fuel designers have introduced the use of 'advanced' fuel types, including doped fuels. Completing a systematic program to acquire data on the basic properties of these fuels, this project measured the specific heat and density of high burn-up UO2 and (U, Gd)O2 using irradiated materials of the same origin as those on which thermal diffusivity measurements had previously been made and thermal recovery phenomena investigated.

2000-12-31T23:59:59.000Z

367

Electron-donor dopant, method of improving conductivity of polymers by doping therewith, and a polymer so treated  

SciTech Connect

Polymers with conjugated backbones, both polyacetylene and polyaromatic heterocyclic types, are doped with electron-donor agents to increase their electrical conductivity. The electron-donor agents are either electride dopants made in the presence of lithium or dopants derived from alkalides made in the presence of lithium. The dopants also contain a metal such as cesium and a trapping agent such as a crown ether.

Liepins, Raimond (Los Alamos, NM); Aldissi, Mahmoud (Los Alamos, NM)

1988-01-01T23:59:59.000Z

368

Enhancement of thermopower of TAGS-85 high-performance thermoelectric materials by doping with the rare earth Dy  

SciTech Connect

Enhancement of thermopower is achieved by doping the narrow-band semiconductor Ag{sub 6.52}Sb{sub 6.52}Ge{sub 36.96}Te{sub 50} (acronym TAGS-85), one of the best p-type thermoelectric materials, with 1 or 2% of the rare earth dysprosium (Dy). Evidence for the incorporation of Dy into the lattice is provided by X-ray diffraction and increased orientation-dependent local fields detected by {sup 125}Te NMR spectroscopy. Since Dy has a stable electronic configuration, the enhancement cannot be attributed to 4f-electron states formed near the Fermi level. It is likely that the enhancement is due to a small reduction in the carrier concentration, detected by {sup 125}Te NMR spectroscopy, but mostly due to energy filtering of the carriers by potential barriers formed in the lattice by Dy, which has large both atomic size and localized magnetic moment. The interplay between the thermopower, the electrical resistivity, and the thermal conductivity of TAGS-85 doped with Dy results in an enhancement of the power factor (PF) and the thermoelectric figure of merit (ZT) at 730 K, from PF = 28 ?W cm{sup ?1} K{sup ?2} and ZT ? 1.3 in TAGS-85 to PF = 35 ?W cm{sup ?1} K{sup ?2} and ZT ? 1.5 in TAGS-85 doped with 1 or 2% Dy for Ge. This makes TAGS-85 doped with Dy a promising material for thermoelectric power generation.

Levin, Evgenii; Budko, Serfuei; Schmidt-Rohr, Klaus

2012-04-10T23:59:59.000Z

369

Growth of undoped and chromium-doped CdSxSe1-x crystals by the physical vapor transport method  

Science Conference Proceedings (OSTI)

Chromium-doped CdSe is one of the host materials being considered for solid-state tunable mid-infrared (IR) lasers. Alloying CdSe with CdS allows the increase of the thermal conductivity of the crystal (for CdS the thermal conductivity is a factor of ... Keywords: Cr2+:CdSSe, photoluminescence, physical vapor transport, tunable mid-IR solid-state lasers

U. N. Roy; Y. Cui; C. Barnett; K.-T. Chen; A. Burger; Jonathan T. Goldstein

2002-07-01T23:59:59.000Z

370

Growth of Cr- and Co-doped CdSe crystals from high-temperature selenium solutions  

Science Conference Proceedings (OSTI)

Transition metals in the group II-VI semiconductors have attracted considerable attention for their application as tunable mid-infrared (IR) lasers at room temperature. Very recently, Co-doped II-VI hosts have been considered as saturable absorber materials. ... Keywords: Beer-Lambert law, II-VI semiconductor, electrical resistivity, glow discharge mass spectrometric (GDMS), mid-infrared solid-state laser, optical transmission

O. O. Adetunji; N. Roy; Y. Cui; G. Wright; J.-O. Ndap; A. Burger

2002-07-01T23:59:59.000Z

371

Three orders of magnitude cavity-linewidth narrowing by slow light in a rare-earth-ion-doped crystal cavity  

E-Print Network (OSTI)

Three orders of magnitude cavity-linewidth narrowing in a rare-earth-ion-doped crystal cavity, induced by strong intra-cavity dispersion caused by off-resonant interaction with dopant ions is demonstrated. The strong dispersion is created by semi-permanent but rapidly reprogrammable changes of the rare earth absorption profiles using optical pumping techniques. Several cavity modes are shown within the spectral transmission window. Potential applications are discussed.

Sabooni, Mahmood; Rippe, Lars; Kröll, Stefan

2013-01-01T23:59:59.000Z

372

Preparation, characterization of the Ta-doped ZnO nanoparticles and their photocatalytic activity under visible-light illumination  

SciTech Connect

This paper describes a novel catalyst of the Ta-doped ZnO nanocrystals prepared by a modified polymerizable complex method using the water-soluble tantalum precursor as the sources of Ta. The catalysts were characterized by means of various analytical techniques as a function of Ta content (x=0-4 mol%) systematically. A remarkable advantage of the results was confirmed that dopant Ta enhanced the visible-light absorption of ZnO and the low-solubility tantalum doping could restrain the growth of crystal and minish the particle size. The relationship between the physicochemical property and the photocatalytic performance was discussed, and it was found that the photocatalytic activity in the photochemical degradation of methylene blue under visible-light irradiation (lambda>=420 nm) was dependent on the contents of the dopant, which could affect the particle size, concentration of surface hydroxyl groups and active hydrogen-related defect sites, and the visible-light absorption. The highest photocatalytic activity was obtained for the 1.0 mol% Ta-doped ZnO sample. - Graphical abstract: The addition of the tantalum into ZnO prepared by a modified polymerizable complex method not only restrains the growth of crystal, minish the particle size, but also changes the nanocrystal morphology.

Kong Jizhou [National Laboratory of Solid State Microstructures, Materials Science and Engineering Department, Nanjing University, Nanjing 210093 (China); Li Aidong, E-mail: adli@nju.edu.c [National Laboratory of Solid State Microstructures, Materials Science and Engineering Department, Nanjing University, Nanjing 210093 (China); Zhai Haifa; Gong Youpin; Li Hui; Wu Di [National Laboratory of Solid State Microstructures, Materials Science and Engineering Department, Nanjing University, Nanjing 210093 (China)

2009-08-15T23:59:59.000Z

373

High-pressure structural phase transitions in chromium-doped BaFe[subscript 2]As[subscript 2  

Science Conference Proceedings (OSTI)

We report on the results from high pressure x-ray powder diffraction and electrical resistance measurements for hole doped BaFe{sub 2-x}Cr{sub x}As{sub 2} (x = 0, 0.05, 0.15, 0.4, 0.61) up to 81 GPa and down to 10 K using a synchrotron source and diamond anvil cell (DAC). At ambient temperature, an isostructural phase transition from a tetragonal (T) phase (I4/mmm) to a collapsed tetragonal (CT) phase is observed at 17 GPa. This transition is found to be dependent on ambient pressure unit cell volume and is slightly shifted to higher pressure upon increase in the Cr-doping. Unlike BaFe{sub 2}As{sub 2} which superconduct under high pressure, we have not detected any evidence of pressure induced superconductivity in chromium doped samples in the pressure and temperature range of this study. The measured equation of state parameters are presented for both the tetragonal and collapsed tetragonal phases for x = 0.05, 0.15, 0.40 and 0.61.

Uhoya, W.O.; Montgomery, J.M.; Samudrala, G.K.; Tsoi, G.M.; Vohra, Y.K.; Weir, S.T.; Sefat, A.S. (UAB); (LLNL); (ORNL)

2012-10-23T23:59:59.000Z

374

Light-induced structural changes in Eu-doped (Pb,La)(Zr,Ti)O{sub 3} ceramics  

SciTech Connect

Fluorescence spectra of poled and unpoled Eu-doped (Pb,La)(Zr,Ti)O{sub 3} ceramics with various compositions were measured using 580 nm excitation. The ratio of the intensities of the Eu{sup 3+} {sup 5}D{sub 0}{yields}{sup 7}F{sub 2}/{sup 5}D{sub 0}{yields}{sup 7}F{sub 1} fluorescence transitions was used as an indicator for the symmetry of the Eu{sup 3+} site. As the symmetry decreases, the ratio increases. Increasing the Zr content in (Pb,La)(Zr,Ti)O{sub 3} increases the ratio, indicating that the symmetry of the Eu{sup 3+} site decreases. Exposure of the Eu-doped (Pb,La)(Zr,Ti)O{sub 3} samples to UV light also increases the intensity ratio, indicating that UV light exposure leads to structural distortions in Eu-doped (Pb,La)(Zr,Ti)O{sub 3} samples, lowering the Eu{sup 3+} site symmetry.

Myint, Thandar; Gunawidjaja, Ray; Eilers, Hergen [Applied Sciences Laboratory, Institute for Shock Physics, Washington State University, Spokane, Washington 99210-1495 (United States)

2011-04-25T23:59:59.000Z

375

ZnO:Al Doping Level and Hydrogen Growth Ambient Effects on CIGS Solar Cell Performance: Preprint  

DOE Green Energy (OSTI)

Cu(In,Ga)Se2 (CIGS) photovoltaic (PV) cells require a highly conducting and transparent electrode for optimum device performance. ZnO:Al films grown from targets containing 2.0 wt.% Al2O3 are commonly used for this purpose. Maximum carrier mobilities of these films grown at room temperature are ~20-25 cm2V-1s-1. Therefore, relatively high carrier concentrations are required to achieve the desired conductivity, which leads to free carrier absorption in the near infrared (IR). Lightly doped films (0.05 - 0.2 wt.% Al2O3), which show less IR absorption, reach mobility values greater than 50 cm2V-1s-1 when deposited in H2 partial pressure. We incorporate these lightly doped ZnO:Al layers into CIGS PV cells produced at the National Renewable Energy Laboratory (NREL). Preliminary results show quantum efficiency values of these cells rival those of a past world-record cell produced at NREL that used 2.0 wt.% Al-doped ZnO films. The highest cell efficiency obtained in this trial was 18.1%.

Duenow, J. N.; Gessert, T. A.; Wood, D. M.; Egaas, B.; Noufi, R.; Coutts,T. J.

2008-05-01T23:59:59.000Z

376

Structural Properties of Eu-Doped GaN Investigated by Raman Spectroscopy  

DOE Green Energy (OSTI)

Rare-earth (RE) impurities doped GaN are highly promising candidates for light emitting device applications due to their efficient electroluminescence properties at room temperature. Among those, Eu doped GaN has been identified as an excellent material for the red spectral region due to its strong emission at 620 nm. As a transition internal to the Eu doping atom (4f-4f), light emission originates in a much smaller complex than the more flexibly controllable quantum structures of wells, wires, and dots. This is thought to make the center less susceptible to structural defects and in particular radiation damage in the lattice host. Nevertheless, the lattice host is crucial for providing the excitation in from of free electrons and holes. In this respect, the actual lattice site Eu occupies in the host lattice, i.e. in GaN, is important. A large fraction of Eu atoms are typically inactive which must be attributed to their lattice site and local environment. GaN films implanted with Eu to concentrations of {approx}10{sup 18} cm{sup -3} were subjected to a highly directed beam of 500 keV He{sup +} at a dose of 5 x 10{sup 14} cm{sup -2}. By means of a shadow mask, irradiated and unexposed regions lie very close to each other on the same sample. We used optical and structural analysis to identify the exerted radiation damage. At the full radiation dose, photoluminescence intensity has decayed to {approx}0.01 of its initial value. From the dose dependence of the radiation decay we previously concluded, that this decay is in part due to the destruction of radiative Eu sites [J.W. Tringe, unpublished (2006)]. Along the transition from virgin to irradiated material we analyze the accumulated damage in terms of surface morphology (atomic force microscopy), crystallinity (x-ray diffraction), and phonon dispersion using micro-Raman spectroscopy. In addition to the well-studied E{sub 2}(high) mode, two new vibrational modes at 659 cm{sup -1} and 201 cm{sup -1} were observed in the Eu implanted and annealed sample, prior to He{sup +} irradiation. These modes are either remnants of the implantation damage or related to the Eu impurity. As such they can be indicative of the actual lattice site the Eu atom resides on. After irradiation, broad Raman modes at 300 cm-1 are being observed. This band indicates disorder activated Raman scattering (DARS) due to the radiation damage. An additional narrow mode appears at 672 cm{sup -1}, which can possibly be due to a nitrogen vacancy related vibrational mode. The continuous transition from irradiated to un-irradiated sample allows the direct evolution of radiation damage and its coordinated effects in structural, optical and vibrational properties. By its systematic correlation we anticipate to be able to elucidate the Eu lattice interaction and the processes of radiation damage.

Senawiratne, J; Xia, Y; Detchprohm, T; Tringe, J W; Stevens, C G; Wetzel, C

2006-06-20T23:59:59.000Z

377

Plasma Synthesized Doped Boron Nanopowder for MgB2 Superconductors  

DOE Green Energy (OSTI)

Under this program, a process to synthesize nano-sized doped boron powder by a plasma synthesis process was developed and scaled up from 20 gram batches at program start to over 200 grams by program end. Over 75 batches of boron nanopowder were made by RF plasma synthesis. Particle sizes were typically in the 20-200 nm range. The powder was synthesized by the reductive pyrolysis of BCl{sub 3} in hydrogen in an RF plasma. A wide range of process parameters were investigated including plasma power, torch geometry, gas flow rates, and process pressure. The powder-in-tube technique was used to make monofilament and multifilament superconducting wires. MgB{sub 2} wire made with Specialty Materials plasma synthesized boron nanopowder exhibited superconducting properties that significantly exceeded the program goals. Superconducting critical currents, J{sub c}, in excess of 10{sup 5} A cm{sup -2} at magnetic fields of 8 tesla were reproducibly achieved. The upper critical magnetic field in wires fabricated with program boron powder were H{sub c2}(0) = 37 tesla, demonstrating the potential of these materials for high field magnet applications. T{sub c} in carbon-doped MgB{sub 2} powder showed a systematic decrease with increasing carbon precursor gas flows, indicating the plasma synthesis process can give precise control over dopant concentrations. Synthesis rates increased by a factor of 400% over the course of the program, demonstrating the scalability of the powder synthesis process. The plasma synthesis equipment at Specialty Materials has successfully and reproducibly made high quality boron nanopowder for MgB{sub 2} superconductors. Research and development from this program enabled Specialty Materials to successfully scale up the powder synthesis process by a factor of ten and to double the size of its powder pilot plant. Thus far the program has been a technical success. It is anticipated that continued systematic development of plasma processing parameters, dopant chemistry and concentration, wire processing technology, and collection technology will lead to the commercialization of boron nanopowder as a precursor for MgB{sub 2} superconductors. Potential commercial applications include magnets for magnetic resonance imaging (MRI), fault current limiters, wind turbine generators.

James V. Marzik

2012-03-26T23:59:59.000Z

378

Topological defects from doping and quenched disorder in artificial ice systems  

SciTech Connect

We examine the ice-rule obeying and ice-rule breaking vertices in an artificial spin ice system created using magnetic vortices in type-II superconductors with nanostructured pinning arrays. We show that this system can be doped by changing the external field to move the number of vortices away from commensurability and create sites that contain two or zero vortices. For a square ice, the doping leads to the formation of a grain boundary of vertices that do not obey the ice rules. In commensurate systems where the ice rules are obeyed, we can introduce random disorder at the individual pinning sites to create regions where vortices may not be able to flip from one side of the trap to another. For weak disorder, all of the vertices still obey the ice rules, while at intermediate levels of disorder we find grain boundaries of vertices which do not obey the ice rules. For strong disorder it is possible to create isolated paired vertices that do not obey the ice rules. In summary, we have shown that an artificial square ice can be created using vortices in a type-II superconductor interacting with a periodic array of pinning sites where each site has a double well potential. By defining the direction of the effective spin according to the side of the double well occupied by the vortex, we find that this system obeys the ice rules for square ice. We add disorder to the system in the form of randomness of the height of the potential barrier at the center of the well, and obtain vertex configurations using a rotating drive protocol which is similar to the shaking ac magnetic field used in nanomagnetic systems. For weak disorder the entire system still obeys the square ice rules. For intermediate disorder, ice-rule breaking vertices appear and form grain boundaries, while for strong disorder there are both gain boundaries and isolated paired defects. In a system with uniform potential barrier heights, we introduce disorder by moving away from commensurability and creating Home pinning sites that contain two or zero vortices. In this case we find grain boundaries that emanate from the defect site and span the sample.

Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory; Libal, A [BABES-BOLYAI UNIV

2010-01-01T23:59:59.000Z

379

Investigation of Ti-doped NaAlH4 by solid-state NMR  

DOE Green Energy (OSTI)

In recent years, the development of Ti-doped NaAlH{sub 4} as a hydrogen storage material has gained attention because of its large weight percentage of hydrogen ({approx}5%) compared to traditional interstitial hydrides. The addition of transition-metal dopants, in the form of Ti-halides, such as TiCl{sub 3}, dramatically improves the kinetics of the absorption and desorption of hydrogen from NaAlH{sub 4}. However, the role that Ti plays in enhancing the absorption and desorption of H{sub 2} is still unknown. In the present study, {sup 27}Al, {sup 23}Na, and {sup 1}H MAS (Magic Angle Spinning) NMR (Nuclear Magnetic Resonance) has been performed to understand the titanium speciation in Ti-doped NaAlH{sub 4}. All experiments were performed on a sample of crushed single crystals exposed to Ti during growth, a sample of solvent-mixed 4TiCl{sub 3} + 112NaAlH{sub 4}, a reacted sample of solvent-mixed TiCl{sub 3} + {sup 3}NaAlH{sub 4} with THF, and a reacted sample of ball-milled TiCl3 + 3NaAlH{sub 4}. The {sup 27}Al MAS NMR has shown differences in compound formation between solvent-mixed TiCl{sub 3} + 3NaAlH{sub 4} with THF and the mechanically ball-milled TiCl{sub 3} + 3NaAlH{sub 4}. {sup 27}Al MAS NMR of the mechanically ball-milled mixture of fully-reacted TiCl{sub 3} + 3NaAlH{sub 4} showed spectral signatures of TiAl{sub 3} while, the solvent-mixed 4TiCl{sub 3} + 112NaAlH{sub 4}, which is totally reacted, does not show the presences of TiAl{sub 3}, but shows the existence of Al{sub 2}O{sub 3}.

Maxwell, R; Majzoub, E; Herberg, J

2003-11-24T23:59:59.000Z

380

Transport Properties of Bilayer Graphene Nanoribbons  

E-Print Network (OSTI)

1997; pp 105-214. 115. Volk, C. ; Fringes, S. ; Terreés,3586. 116. Fringes, S. ; Volk, C. ; Norda, C. ; Terrés, B. ;

Wang, Minsheng

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Transport Properties of Bilayer Graphene Nanoribbons  

E-Print Network (OSTI)

Electrical spin injection and transport in germanium”. Phys.P. , Temperature- Dependent Transport in Suspended Graphene.Y. M. , Quantum Transport: Introduction to Nanoscience.

Wang, Minsheng

2013-01-01T23:59:59.000Z

382

Investigation of Hybrid Bilayer Membranes with Neutron ...  

Science Conference Proceedings (OSTI)

... The wafer was then etched in a solution of 57% nitric acid, 18% hydro- fluoric acid, and 25% acetic acid for an experimentally determined amount of ...

2003-01-16T23:59:59.000Z

383

Functionally Graded Piezomagnetic and Piezoelectric Bilayers for ...  

Science Conference Proceedings (OSTI)

Optical Properties of Bifeo3: Polar Oxides for Fundamental Science and Solar Energy Applications · Piezoelectric Fiber Fabrication for Magnetoelectric Sensors

384

Transport Properties of Bilayer Graphene Nanoribbons  

E-Print Network (OSTI)

operation in single-layer graphene ferroelectric memory”.Mobility in Suspended Graphene. Solid State Commun. 2008,Transport in Suspended Graphene. Phys. Rev. Lett. 2008,

Wang, Minsheng

2013-01-01T23:59:59.000Z

385

Electron Doping by Charge Transfer at LaFeO 3 /Sm 2 CuO 4 Epitaxial Interfaces  

SciTech Connect

The breakdown of the lattice translational invariance symmetry that occurs at complex oxide interfaces may profoundly modify their electronic structure, leading to interfacial states with properties drastically different from those of the superlattice individual components. The appearance of a conducting two dimensional (2D) electron gas at the interface between two insulating oxides and induced magnetism in a non-magnetic material are just two among many fascinating examples. [ 1 8 ] One of the key factors underlying novel properties is the modifi cation of the doping and orbital occupancy near those interfaces, which may result from charge transfer processes. [ 3 , 9 11 ] If materials used in heterostructures have different work functions, a non-equilibrium situation will be created at the interface and charge will be transferred until the chemical potential levels off. [ 12 ] The use of such phenomena to modify doping in heterostructures has been proposed theoretically as a new route to avoid the quenched disorder that inevitably accompanies the chemical doping. At the interface between a Mott insulating parent compound of the high critical temperature superconductor (HTSC) family and a suitable material that would act as the charge donor, electron doped phases could be stabilized which would eventually turn metallic and perhaps superconducting. [ 12 , 13 ] Such charge transfer processes have been observed at interfaces involving copper oxides such as La 0.7 Ca 0.3 MnO 3 / YBa 2 Cu 3 O 7 , [ 14 ] La 2 x Sr x CuO 4 /La 2 CuO 4 [ 15 ] and SrTi 1 x Nb x O 3 / Sm 2 CuO 4 . [ 16 ] While a novel 2D superconducting state was found at the La 2-x Sr x CuO 4 /La 2 CuO 4 interface, [ 17 ] the effect of doping by charge transfer could not be examined in the other two cases due to the detrimental effect on the YBa 2 Cu 3 O 7 superconductivity of the spin polarized electrons from La 0.7 Ca 0.3 MnO 3 in one case and due to the conducting nature of the SrTi 1 x Nb x O 3 in the other case, which obscures changes in the conducting properties of the interface layer. In this paper, the structural and

Bruno, Flavio Y. [Universidad Complutense, Spain; Schmidt, R [Universidad Complutense de Madrid, Spain; Varela, Maria [UCM, Dept Fis Aplicada 3, Madrid, Spain; Garcia-Barriocanal, Javier [Universidad Complutense, Spain; Rivera-Calzada, Alberto [Universidad Complutense, Spain; Cuellar, F. [Universidad Complutense de Madrid, Spain; Leon, Carlos [Universidad Complutense de Madrid, Spain; Thakur, P. [European Synchrotron Radiation Facility (ESRF); Cezar, J. C. [European Synchrotron Radiation Facility (ESRF); Brookes, N. B. [European Synchrotron Radiation Facility (ESRF); Garcia-Hernandez, M [Instituto de Ciencia de Materiales de Madrid (ICMM); Dagotto, Elbio R [ORNL; Pennycook, Stephen J [ORNL; Santamaria, J. [Universidad Complutense, Spain

2013-01-01T23:59:59.000Z

386

XRD and IR Studies of Yb{sup 3+} Doped Tellurite Glass  

Science Conference Proceedings (OSTI)

Ytterbium doped sodium-tellurite glasses having composition of (80-x) TeO{sub 2}-20Na{sub 2}O-(x)Yb{sub 2}O{sub 3}(where x = 0.0-2.0 mol%) are prepared by melt quenching technique. The crystallinity of the glass has been examined using X-ray diffraction technique. All glass are found to be amorphous in nature. Meanwhile the transmission spectroscopy is determine by using Infrared Spectroscopy. It is found that the absorption vibrational spectra occurs at range 3405-3423 cm{sup -1}, 1632-1643 cm{sup -1}, 1377-1382 cm{sup -1}, 721-732 cm{sup -1} and 589-606 cm{sup -1} peaks. The predominant peaks around 700 cm{sup -1} is due to the Te-O-Te vibration while peak at 600 cm{sup -1} is due to the vibration of Yb{sup 3+} ions.

Sahar, M. R.; Isa, H. Noor [Advanced Optical Material Reseach Group, Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai Johor Bahru (Malaysia)

2011-03-30T23:59:59.000Z

387

Lifetime and diffusion length measurements on silicon material and solar cells. [Intentionally doped with impurities  

DOE Green Energy (OSTI)

Experimental methods were evaluated for the determination of lifetime and diffusion length in silicon intentionally doped with potentially lifetime-degrading impurities found in metallurgical grade silicon, impurities which may be residual in low-cost silicon intended for use in terrestrial flat-plat arrays. Results obtained by these methods were compared for mutual consistency. Lifetime measurements were made using a steady-state photoconductivity method, which was compared with a photoconductivity decay technique. Diffusion length determinations were made using short-circuit current measurements under penetrating illumination. This method was compared with a direct measurement of diffusion length using a scanning electron microscope. Mutual consistency among all experimental methods was verified, but steady-state photoconductivity was found preferable to photoconductivity decay at short lifetimes and in the presence of traps. The effects of a number of impurities on lifetime in bulk material, and on diffusion length in cells fabricated from this material, were determined. Results were compared with those obtained by others on the same material and devices using different techniques. General agreement was found in terms of the hierarchy of impurities which degrade the lifetime.

Othmer, S.; Chen, S.C.

1977-01-01T23:59:59.000Z

388

Highly ordered Zn-doped mesoporous silica: An efficient catalyst for transesterification reaction  

Science Conference Proceedings (OSTI)

Designing highly ordered material with nanoscale periodicity is of great significance in the field of solid state chemistry. Herein, we report the synthesis of highly ordered 2D-hexagonal mesoporous zinc-doped silica using a mixture of anionic and cationic surfactants under hydrothermal conditions. Powder XRD, N{sub 2} sorption, TEM analysis revealed highly ordered 2D-hexagonal arrangements of the pores with very good surface area (762 m{sup 2} g{sup -1}) in this Zn-rich mesoporous material. Chemical analysis shows very high loading of zinc (ca. 12.0 wt%) in the material together with retention of hexagonal pore structure. Interestingly, high temperature calcination resulted into zinc silicate phase, unlike any ZnO phase, which otherwise is expected under heat treatments. High surface area together with Zn loading in this mesoporous material has been found useful for the catalytic activity of the materials in the acid-catalyzed transesterification reactions of various esters under mild liquid phase conditions. - Graphical abstract: Zn-rich 2D-hexagonal mesoporous materials are synthesized hydrothermally, which show very good catalytic activity in the transesterification reaction under mild liquid phase reaction conditions. Highlights: > Zn-rich 2D-hexagonal mesoporous silica. > High surface area material. > Efficient catalyst in liquid phase transesterification reaction. > Biodiesel production.

Pal, Nabanita; Paul, Manidipa [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Bhaumik, Asim, E-mail: msab@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

2011-07-15T23:59:59.000Z

389

Threshold concentrations in zinc-doped lithium niobate crystals and their structural conditionality  

SciTech Connect

On the basis of precise X-ray diffraction study of lithium niobate single crystals of congruent composition and four zinc-doped (at 2.8, 5.2, 7.6, and 8.2 mol %) crystals, structural conditionality of the threshold concentrations of the dopant has been established. At these concentrations, the mechanism of zinc incorporation into crystal changes. As the zinc concentration increases, this element first substitutes excess niobium, localized in lithium positions, with a simultaneous decrease in the number of vacancies in these positions. Then zinc substitutes lithium with formation of new lithium vacancies. When a certain limit on the number of vacancies is reached, zinc begins to substitute niobium in its main positions. This process is naturally accompanied by a decrease in the number of vacancies to their complete disappearance and formation of a self-compensating crystal. The character of the dependence of the crystal physical properties on the dopant concentration changes specifically when the impurity concentration passes through the threshold values.

Chernaya, T. S.; Volk, T. R.; Verin, I. A.; Simonov, V. I., E-mail: simonov@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2008-07-15T23:59:59.000Z

390

Surface Composition, Work Function, and Electrochemical Characteristics of Gallium-Doped Zinc Oxide  

Science Conference Proceedings (OSTI)

Gallium-doped zinc oxide (GZO) possesses the electric conductivity, thermal stability, and earth abundance to be a promising transparent conductive oxide replacement for indium tin oxide electrodes in a number of molecular electronic devices, including organic solar cells and organic light emitting diodes. The surface chemistry of GZO is complex and dominated by the hydrolysis chemistry of ZnO, which influences the work function via charge transfer and band bending caused by adsorbates. A comprehensive characterization of the surface chemical composition and electrochemical properties of GZO electrodes is presented, using both solution and surface adsorbed redox probe molecules. The GZO surface is characterized using monochromatic X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy after the following pretreatments: (i) hydriodic acid etch, (ii) potassium hydroxide etch, (iii) RF oxygen plasma etching, and (iv) high-vacuum argon-ion sputtering. The O 1s spectra for the GZO electrodes have contributions from the stoichiometric oxide lattice, defects within the lattice, hydroxylated species, and carbonaceous impurities, with relative near-surface compositions varying with pretreatment. Solution etching procedures result in an increase of the work function and ionization potential of the GZO electrode, but yield different near surface Zn:Ga atomic ratios, which significantly influence charge transfer rates for a chemisorbed probe molecule. The near surface chemical composition is shown to be the dominant factor in controlling surface work function and significantly influences the rate of electron transfer to both solution and tethered probe molecules.

Ratcliff, E. L.; Sigdel, A. K.; Macech, M. R.; Nebesny, K.; Lee, P. A.; Ginley, D. S.; Armstrong, N. R.; Berry, J. J.

2012-06-30T23:59:59.000Z

391

Grain boundary structure and solute segregation in titanium-doped sapphire bicrystals  

SciTech Connect

Solute segregation to ceramic grain boundaries governs material processing and microstructure evolution, and can strongly influence material properties critical to engineering performance. Understanding the evolution and implications of grain boundary chemistry is a vital component in the greater effort to engineer ceramics with controlled microstructures. This study examines solute segregation to engineered grain boundaries in titanium-doped sapphire (Al2O3) bicrystals, and explores relationships between grain boundary structure and chemistry at the nanometer scale using spectroscopic and imaging techniques in the transmission electron microscope (TEM). Results demonstrate dramatic changes in solute segregation stemming from small fluctuations in grain boundary plane and structure. Titanium and silicon solute species exhibit strong tendencies to segregate to non-basal and basal grain boundary planes, respectively. Evidence suggests that grain boundary faceting occurs in low-angle twis t boundaries to accommodate nonequilibrium solute segregation related to slow specimen cooling rates, while faceting of tilt grain boundaries often occurs to expose special planes of the coincidence site lattice (CSL). Moreover, quantitative analysis of grain boundary chemistry indicates preferential segregation of charged defects to grain boundary dislocations. These results offer direct proof that static dislocations in ionic materials can assume a net charge, and emphasize the importance of interactions between charged point, line, and planar defects in ionic materials. Efforts to understand grain boundary chemistry in terms of space charge theory, elastic misfit and nonequilibrium segregation are discussed for the Al2O3 system.

Taylor, Seth T.

2002-05-17T23:59:59.000Z

392

Synthesis, properties and applications of pure and covalently doped DLC films prepared by energetic condensation  

Science Conference Proceedings (OSTI)

Hyper-thermal species have been used to produce carbon-based films with mechanical and tribological properties that have greatly expanded the applications of amorphous carbon coatings. Tetragonally bonded amorphous carbon films have properties that approach that of diamond in several ways. The major drawback, namely intrinsic stresses, preventing the production of thick ta-C films has been overcome by heat treating these films, and presently several micrometer-thick films of ta-C are regularly produced. Yet another area where superhard coatings are of great interest is for wear applications at elevated temperatures, namely around 500 degrees C and above. Such temperatures may be environment temperatures, or localized (flash) temperatures resulting for instance from wear. For this applications, doping the ta-C with elements that are covalently bonded to C (such as Si and B) offers a promising alternative. In this article, I will discuss some treatments that have allowed expanding the applications of pure ta-C, and the incorporation of Si and B on ta-C films. Film properties are presented and discussed.

Monteiro, Othon R.

2001-12-04T23:59:59.000Z

393

Synthesis and characterization of ZnO and Ni doped ZnO nanorods by thermal decomposition method for spintronics application  

SciTech Connect

Zinc oxide nanorods and diluted magnetic semiconducting Ni doped ZnO nanorods were prepared by thermal decomposition method. This method is simple and cost effective. The decomposition temperature of acetate and formation of oxide were determined by TGA before the actual synthesis process. The X-ray diffraction result indicates the single phase hexagonal structure of zinc oxide. The transmission electron microscopy and scanning electron microscopy images show rod like structure of ZnO and Ni doped ZnO samples with the diameter {approx} 35 nm and the length in few micrometers. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The Ni doped ZnO exhibits room temperature ferromagnetism. This diluted magnetic semiconducting Ni doped ZnO nanorods finds its application in spintronics. - Highlights: Black-Right-Pointing-Pointer The method used is very simple and cost effective compared to all other methods for the preparation DMS materials. Black-Right-Pointing-Pointer ZnO and Ni doped ZnO nanorods Black-Right-Pointing-Pointer Ferromagnetism at room temperature.

Saravanan, R.; Santhi, Kalavathy [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600 025 (India); Sivakumar, N. [Amrita Center for Nanosciences, Amrita Research Institute, Kochi-682 041 (India); Narayanan, V. [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai-600 025 (India); Stephen, A., E-mail: stephen_arum@hotmail.com [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600 025 (India)

2012-05-15T23:59:59.000Z

394

Electron and hole gas in modulation-doped GaAs/Al{sub 1-x}Ga{sub x}As radial heterojunctions  

Science Conference Proceedings (OSTI)

We perform self-consistent Schroedinger-Poisson calculations with exchange and correlation corrections to determine the electron and hole gas in a radial heterojunction formed in a GaAs/AlGaAs core-multi-shell nanowire, which is either n- or p-doped. We show that the electron and hole gases can be tuned to different localizations and symmetries inside the core as a function of the doping density/gate potential. Contrary to planar heterojunctions, conduction electrons do not form a uniform 2D electron gas (2DEG) localized at the GaAs/AlGaAs interface, but rather show a transition between an isotropic, cylindrical distribution deep in the GaAs core (low doping) and a set of six tunnel-coupled quasi-1D channels at the edges of the interface (high doping). Holes, on the other hand, are much more localized at the GaAs/AlGaAs interface. At low doping, they present an additional localization pattern with six separated 2DEGs strips. The field generated by a back-gate may easily deform the electron or hole gas, breaking the sixfold symmetry. Single 2DEGs at one interface or multiple quasi-1D channels are shown to form as a function of voltage intensity, polarity, and carrier type.

Bertoni, Andrea; Royo, Miquel; Mahawish, Farah; Goldoni, Guido [CNR-NANO S3, Istituto Nanoscienze, Via Campi 213/a, 41125 Modena (Italy); Department of Physics, University of Modena and Reggio Emilia and CNR-NANO S3, Istituto Nanoscienze, Via Campi 213/a, 41125 Modena (Italy)

2011-11-15T23:59:59.000Z

395

Dielectric and ferroelectric response of compositionally graded bilayer and trilayer composites of BaTiO{sub 3} and 0.975BaTiO{sub 3}-0.025Ba(Cu{sub 1/3}Nb{sub 2/3})O{sub 3}  

Science Conference Proceedings (OSTI)

In this paper, we report the dielectric and ferroelectric response of compositionally graded bilayer and trilayer composites consisting of BaTiO{sub 3} (BT) and 0.975BaTiO{sub 3}-0.025Ba(Cu{sub 1/3}Nb{sub 2/3})O{sub 3} (BTBCN). Two types of graded bilayer samples were synthesized, one with same thickness of BT and BTBCN while other with different layer thicknesses. The graded trilayer sample consisted of BT layer sandwiched between two BTBCN layers of equal thickness. Scanning electron microscopy and transmission electron microscopy images showed a sharp interface with needle-shape domains across the interface. The domain size on BT side was found to be larger than that on BTBCN side. The temperature dependence of dielectric response for all composite systems was found to exhibit shifting in characteristic Curie peak compared to constituent material which was associated to coupling between layers. Moreover, the differences in grain size, tetragonality, domain mobility of each layer was found to perturb the electrical response of composite. The polarization mismatch between uncoupled BT and BTBCN established internal electric field in composite specimen and defined new polarization states in each layer by perturbing free energy functional of the composite specimen. Dynamic hysteresis behaviors and power-law scaling relations of all specimens were determined from polarization-electric field hysteresis loop measurements as a function of frequency. All systems were found to exhibit similar dynamic scaling relationships. Hysteresis area , P{sub r}, and E{sub C} decreased with increasing frequency due to delayed response but increased with increasing applied electric field due to enhancement of driving force. Trilayer system was found to exhibit strong internal-bias field and double hysteresis behavior. The coupling effect resulting due to polarization mismatch between layers had substantial influence on the dynamic hysteresis behavior and power-law scaling relations.

Maurya, Deepam; Priya, Shashank [CEHMS, Department of Materials Science and Engineering, Virginia Tech, Virginia 24061 (United States); Wongdamnern, Natthapong [Department of Physics and Materials Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yimnirun, Rattikorn [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand)

2010-12-15T23:59:59.000Z

396

Stable hole doping of graphene for low electrical resistance and high optical transparency This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-Print Network (OSTI)

Stable hole doping of graphene for low electrical resistance and high optical transparency.1088/0957-4484/22/42/425701 Stable hole doping of graphene for low electrical resistance and high optical transparency S Tongay1 display high transmittance in the visible and near-infrared spectrum, preserving graphene's optical

Tanner, David B.

397

Physicochemical characterization of point defects in fluorine doped tin oxide films  

SciTech Connect

The physical and chemical properties of spray deposited FTO films are studied using FESEM, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electrical and optical measurements. The results of XRD measurements showed that the films are polycrystalline (grain size 20-50 nm) with Rutile structure and mixed preferred orientation along the (200) and (110) planes. An angular shift of the XRD peaks after F-doping is observed and interpreted as being due to the formation of substitutional fluorine defects (F{sub O}) in presence of high concentration of oxygen vacancies (V{sub O}) that are electrically neutral. The electrical neutrality of oxygen vacancies is supported by the observation that the electron concentration n is two orders of magnitude lower than the V{sub O} concentration calculated from chemical analyses using XPS measurements. It is shown that an agreement between XPS, XRD, and Hall effect results is possible provided that the degree of deviation from stoichiometry is calculated with the assumption that the major part of the bulk carbon content is involved in O-C bonds. High temperature thermal annealing is found to cause an increase in the F{sub O} concentration and a decrease in both n and V{sub O} concentrations with the increase of the annealing temperature. These results could be interpreted in terms of a high temperature chemical exchange reaction between the SnO{sub 2} matrix and a precipitated fluoride phase. In this reaction, fluorine is released to the matrix and Sn is trapped by the fluoride phase, thus creating substitutional fluorine F{sub O} and tin vacancy V{sub Sn} defects. The enthalpy of this reaction is determined to be approximately 2.4 eV while the energy of formation of a V{sub Sn} through the migration of Sn{sub Sn} host atom to the fluoride phase is approximately 0.45 eV.

El Akkad, Fikry; Joseph, Sudeep [Physics Department, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait)

2012-07-15T23:59:59.000Z

398

Thermoelectric material including a multiple transition metal-doped type I clathrate crystal structure  

DOE Patents (OSTI)

A thermoelectric material includes a multiple transition metal-doped type I clathrate crystal structure having the formula A.sub.8TM.sub.y.sub.1.sup.1TM.sub.y.sub.2.sup.2 . . . TM.sub.y.sub.n.sup.nM.sub.zX.sub.46-y.sub.1.sub.-y.sub.2.sub.- . . . -y.sub.n.sub.-z. In the formula, A is selected from the group consisting of barium, strontium, and europium; X is selected from the group consisting of silicon, germanium, and tin; M is selected from the group consisting of aluminum, gallium, and indium; TM.sup.1, TM.sup.2, and TM.sup.n are independently selected from the group consisting of 3d, 4d, and 5d transition metals; and y.sub.1, y.sub.2, y.sub.n and Z are actual compositions of TM.sup.1, TM.sup.2, TM.sup.n, and M, respectively. The actual compositions are based upon nominal compositions derived from the following equation: z=8q.sub.A-|.DELTA.q.sub.1|y.sub.1-|.DELTA.q.sub.2|y.sub.2- . . . -|.DELTA.q.sub.n|y.sub.n, wherein q.sub.A is a charge state of A, and wherein .DELTA.q.sub.1, .DELTA.q.sub.2, .DELTA.q.sub.n are, respectively, the nominal charge state of the first, second, and n-th TM.

Yang, Jihui (Lakeshore, CA); Shi, Xun (Troy, MI); Bai, Shengqiang (Shanghai, CN); Zhang, Wenqing (Shanghai, CN); Chen, Lidong (Shanghai, CN); Yang, Jiong (Shanghai, CN)

2012-01-17T23:59:59.000Z

399

Polarization dependence of two-photon transition intensities in rare-earth doped crystals  

SciTech Connect

A polarization dependence technique has been developed as a tool to investigate phonon scattering (PS), electronic Raman scattering (ERS), and two-photon absorption (TPA) transition intensities in vanadate and phosphate crystals. A general theory for the polarization dependence (PD) of two-photon transition intensities has been given. Expressions for the polarization dependent behavior of two-photon transition intensities have been tabulated for the 32 crystallographic point groups. When the wavefunctions for the initial and final states of a rare-earth doped in crystals are known, explicit PD expressions with no unknown parameters can be obtained. A spectroscopic method for measuring and interpreting phonon and ERS intensities has been developed to study PrVO{sub 4}, NdVO{sub 4}, ErVO{sub 4}, and TmVO{sub 4} crystals. Relative phonon intensities with the polarization of the incident and scattered light arbitrarily varied were accurately predicted and subsequently used for alignment and calibration in ERS measurements in these systems for the first time. Since ERS and PS intensities generally follow different polarization curves as a function of polar angles, the two can be uniquely identified by comparing their respective polarization behavior. The most crucial application of the technique in ERS spectroscopy is the establishment of a stringent test for the Axe theory. For the first time, the F{sub 1}/F{sub 2} ratio extracted from the experimental fits of the ERS intensities were compared with those predicted by theories which include both the second- and third-order contributions. Relatively good agreement between the fitted values of F{sub 1}/F{sub 2} and the predicted values using the second-order theory has been found.

Le Nguyen, An-Dien

1996-05-01T23:59:59.000Z

400

Improvement of near-infrared absorption linewidth in AlGaN/GaN superlattices by optimization of delta-doping location  

Science Conference Proceedings (OSTI)

We report a systematic study of the near-infrared intersubband absorption in AlGaN/GaN superlattices grown by plasma-assisted molecular-beam epitaxy as a function of Si-doping profile with and without {delta}-doping. The transition energies are in agreement with theoretical calculations including many-body effects. A dramatic reduction of the intersubband absorption linewidth is observed when the {delta}-doping is placed at the end of the quantum well. This reduction is attributed to the improvement of interface roughness. The linewidth dependence on interface roughness is well reproduced by a model that considers the distribution of well widths measured with transmission electron microscopy.

Edmunds, C.; Cervantes, M.; Malis, O. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Tang, L.; Shao, J.; Li, D. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, West Lafayette, Indiana 47907 (United States); Gardner, G. [Birck Nanotechnology Center, West Lafayette, Indiana 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Zakharov, D. N. [Birck Nanotechnology Center, West Lafayette, Indiana 47907 (United States); Manfra, M. J. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, West Lafayette, Indiana 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2012-09-03T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


401

Phase control of group velocity in a dielectric slab doped with three-level ladder-type atoms  

Science Conference Proceedings (OSTI)

Propagation of an electromagnetic pulse through a dielectric slab doped with three-level ladder-type atomic systems is discussed. It is shown that the group velocity of the reflected and transmitted pulses can be switched from subluminal to superluminal light propagation by the thickness of the slab or the intensity of the coupling field. Furthermore, it is found that, in the presence of quantum interference, the reflected and transmitted pulses are completely phase dependent. So, the group velocity of the reflected and transmitted pulses can only be switched from subluminal to superluminal by adjusting the relative phase of the applied fields.

Jafari, D. [Department of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of); Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of); Sahrai, M. [Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of); Motavalli, H. [Department of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of); Mahmoudi, M. [Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan (Iran, Islamic Republic of)

2011-12-15T23:59:59.000Z

402

Synthesis of LiNiO2 cathode materials with homogeneous Al doping at the atomic level  

Science Conference Proceedings (OSTI)

Aluminum doped LiNiO2 cathode materials are synthesized by using Raney nickel as the starting material. The structure and composition are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with elemental mapping. The lithium deficiency is analyzed by Rieveld refinement. The initial capacity and retention of capacity are correlated to the lithium deficiency of the resulting cathode material. Using strong oxidant of Li2O2 in the synthesis results in materials with improved electrochemical cyclability. The improvement is related to the diminishing of lithium deficiency in strong oxidizing synthesis conditions.

Liu, Zengcai [ORNL; Zhen, Honghe [Soochow University, Suzhou, People's Republic of China; Kim, Yoongu [ORNL; Liang, Chengdu [ORNL

2011-01-01T23:59:59.000Z

403

Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system  

Science Conference Proceedings (OSTI)

A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

2013-02-12T23:59:59.000Z

404

Spectroscopy and decay kinetics of Pr{sup 3+}-doped chloride crystals for 1300-nm optical amplifiers  

Science Conference Proceedings (OSTI)

Several Pr{sup 3+}-doped chloride crystals have been tested spectroscopically for suitability as 1300-nm optical amplifiers operating on the {sup 1}G{sub 4} - {sup 3}H{sub 5} transition. {sup 1}G{sub 4} lifetimes are much longer than in fluoride hosts, ranging up to 1300 {mu}sec and suggesting a near-unity luminescence quantum yield. Emission spectra are typically broad (FWHM {approximately} 70 nm) and include the 1310-nm zero-dispersion wavelength of standard telecommunications fiber.

Page, R.H.; Schaffers, K.I.; Wilke, G.D. [and others

1995-03-09T23:59:59.000Z

405

Effects of low-temperature postannealing on a n{sup +}-p shallow junction fabricated by plasma doping  

SciTech Connect

A low-temperature activation annealing process following plasma doping (PLAD) was investigated. A dramatic reduction of sheet resistance R{sub s} occurred in the postactivation annealing temperature range of 400 deg. C-480 deg. C after PLAD. The R{sub s} of 30 {omega}/sq. and the junction depth X{sub j} of 30 nm was obtained without the additional diffusion of a dopant from the postactivation annealing in the fabricated junction. The electrical characteristics of a n{sup +}-p junction diode fabricated by PLAD were also improved after low-temperature postannealing.

Im, Kiju; Baek, Sungkweon; Hwang, Hyunsang; Ahn, Chang-Geun; Yang, Jong-Heon; Baek, In-Bok; Lee, Seongjae; Cho, Won-ju [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, 1 Oryongdong, Buk-gu, Gwangju, 500-712 (Korea, Republic of); Nanoelectric Devices Team, Future Technology Research Division, ETRI, 161 Gajeong-dong, Yuseong, Daejeon, 305-350 (Korea, Republic of); Department of Semiconductors and New Materials, College of Electronics and Information, Kwangwoon University, 447-1 Wolgye-Dong, Nowon-Gu, 139-701 (Korea, Republic of)

2005-05-09T23:59:59.000Z

406

Strong room-temperature ferromagnetism of high-quality lightly Mn-doped ZnO grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Strong room-temperature ferromagnetism is demonstrated in single crystalline Mn-doped ZnO grown by molecular beam epitaxy. With a low Mn concentration of 2 Multiplication-Sign 10{sup 19} cm{sup -3}, Mn-doped ZnO films exhibited room-temperature ferromagnetism with a coercivity field larger than 200 Oe, a large saturation moment of 6 {mu}{sub B}/ion, and a large residue moment that is {approx}70% of the saturation magnetization. Isolated ions with long range carrier mediated spin-spin coupling may be responsible for the intrinsic ferromagnetism.

Zuo Zheng; Zhou Huimei; Olmedo, Mario J.; Kong Jieying; Liu Jianlin [Quantum Structures Laboratory, Department of Electrical Engineering, University of California - Riverside, Riverside, California 92521 (United States); Beyermann, Ward P. [Department of Physics and Astronomy, University of California - Riverside, Riverside, California 92521 (United States); Zheng Jianguo [Laboratory for Electron and X-ray Instrumentation, California Institute for Telecommunications and Information Technology, University of California - Irvine, Irvine, California 92697 (United States); Xin Yan [NHMFL, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310-3706 (United States)

2012-09-01T23:59:59.000Z

407

Electrical current suppression in Pd-doped vanadium pentoxide nanowires caused by reduction in PdO due to hydrogen exposure  

SciTech Connect

Pd nanoparticle-doped vanadium pentoxide nanowires (Pd-VONs) were synthesized. Electrical current suppression was observed when the Pd-VON was exposed to hydrogen gas, which cannot be explained by the work function changes mentioned in previous report such as Pd-doped carbon nanotubes and SnO{sub 2} nanowires. Using the x-ray photoelectron spectroscopy, we found that the reduction in PdO due to hydrogen exposure plays an important role in the current suppression of the Pd-VON.

Kim, Byung Hoon; Oh, Soon-Young; Yu, Han Young; Yun, Yong Ju; Kim, Yark Yeon; Hong, Won G. [Electronics and Telecommunications Research Institute (ETRI), Daejeon 305-700 (Korea, Republic of); Jeong, Hu Young; Lee, Jeong Yong [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Kim, Hae Jin [Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of)

2010-04-19T23:59:59.000Z

408

THE EFFECTS OF FLAME TEMPERATURE, PARTICLE SIZE AND EUROPIUM DOPING CONCENTRATION ON THE PROPERTIES OF Y2O3:EU PARTICLES FORMED IN A FLAME AEROSOL PROCESS  

E-Print Network (OSTI)

Y2O3:Eu particles are phosphors that have found wide applications. Flamesynthesized Y2O3:Eu particles may have either the cubic or the monoclinic structure. The effects of particle size and Eu doping concentration on crystal structure and the surface elemental composition of the flame-synthesized Y2O3:Eu particles had not been previously reported. In this study, a flame aerosol process was used to generate polydisperse Y2O3:Eu particle. H2 was used as the fuel gas, with either air or O2 gas as the oxidizer. The precursor was aqueous solutions of the metal nitrates, atomized using a 1.7-MHz ultrasonic atomizer. The product particles were analyzed by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), fluorescence spectrophotometer, and inductively coupled plasma mass spectrometer (ICP-MS). The Y2O3:Eu particles generated in H2/O2 flames were spherical and fully dense, with diameters in the range of 10~3000 nm. In particle samples with lower Eu doping concentrations, a critical particle diameter was found, whose value increased with increasing Eu doping concentration. Particles well below the critical diameter had the monoclinic structure; those well above the critical diameter had the cubic structure. At sufficiently high Eu doping concentrations, all Y2O3:Eu generated in H2/O2 flames had the monoclinic structure. On the other hand, all particles generated in the H2/air flames had the cubic structure. For the Y2O3:Eu particles generated in H2/O2 flames, XPS results showed that the surface Eu concentration was several times higher than the doping concentration. For Y2O3:Eu particles generated in H2/air flames, the surface Eu concentration was equal to the doping concentration. For both types of particles, the photoluminescence intensity reached a maximum corresponding to a surface Eu concentration 40~50%. The photoluminescence intensity then decreased rapidly with higher Eu doping concentration. The effect of particle size and Eu doping concentration on crystal structure may be explained by the interplay between surface energy and polymorphism. A mechanism for this surface enrichment phenomenon was proposed based on the binary Eu2O3-Y2O3 phase diagram.

Yim, Hoon

2009-05-01T23:59:59.000Z

409

Development of Nano-crystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases  

SciTech Connect

This is a final technical report for the first project year from July 1, 2005 to Jan 31, 2012 for DoE/NETL funded project â??DE-FC26-05NT42439: Development of Nanocrystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases.â? This report summarizes the technical progresses and achievements towards the development of novel nanocrystalline doped ceramic material-enabled optical fiber sensors for in situ and real time monitoring the gas composition of flue or hot gas streams involved in fossil-fuel based power generation and hydrogen production.

Hai Xiao; Junhang Dong; Jerry Lin; Van Romero

2011-12-31T23:59:59.000Z

410

Strong Room-Temperature Ferromagnetism in Co2+-Doped TiO2 Made from Colloidal Nanocrystals  

SciTech Connect

Colloidal cobalt-doped TiO{sub 2} (anatase) nanocrystals were synthesized and studied by electronic absorption, magnetic circular dichroism, transmission electron microscopy, magnetic susceptibility, cobalt K-shell X-ray absorption spectroscopy, and extended X-ray absorption fine structure measurements. The nanocrystals were paramagnetic when isolated by surface-passivating ligands, weakly ferromagnetic (M{sub s} {approx} 1.5 x 10{sup -3} {micro}{sub B}/Co{sup 2+} at 300 K) when aggregated, and strongly ferromagnetic (up to M{sub s} = 1.9 {micro}{sub B}/Co{sup 2+} at 300 K) when spin-coated into nanocrystalline films. X-ray absorption data reveal that cobalt is in the Co{sup 2+} oxidation state in all samples. In addition to providing strong experimental support for the existence of intrinsic ferromagnetism in cobalt-doped TiO{sub 2}, these results demonstrate the possibility of using colloidal TiO{sub 2} diluted magnetic semiconductor nanocrystals as building blocks for assembly of ferromagnetic semiconductor nanostructures with potential spintronics applications.

Bryan, John D.; Heald, Steve M.; Chambers, Scott A.; Gamelin, Daniel R.

2004-09-22T23:59:59.000Z

411

Competition between stripe and checkerboard magnetic instabilities in Mn-doped BaFe2As2  

Science Conference Proceedings (OSTI)

The appearance of unconventional superconductivity often requires the suppression of an antiferromagnetic (AFM) ordered state by tuning the chemical composition. In BaFe2As2, the AFM ordered state is driven by Fermi surface nesting, resulting in stripe magnetic ordering with propagation vector Qstripe = (; 0) (in Fe square lattice notation). Co substitution acts as an electron donor that destabilizes the nesting condition,1 leading to suppression of the stripe AFM ordering2 and the appearance of superconductivity.3,4 Mn is nominally the hole-doping counterpart of Co which should also detune the Fermi surface nesting, but it is not a superconductor.5 Here we report that Mn doping does not act solely as a hole donor, but instead introduces strong spin uctuations at a wavevector (; ) that is unrelated to the Fermi surface topology of BaFe2As2. Spin uctuations at (; ) and (; 0) coexist, suggesting the Mn dopants act as local magnetic impurities that polarize neighbouring Fe/Mn spins, potentially disrupting superconductivity.

Pratt, Daniel [Ames Laboratory and Iowa State University; Kim, M. G. [Ames Laboratory and Iowa State University; Ran, S. [Ames Laboratory and Iowa State University; Thaler, A. [Ames Laboratory and Iowa State University; Granroth, Garrett E [ORNL; Marty, Karol J [ORNL; Tian, W. [University of Tennessee, Knoxville (UTK); Zarestky, J. L. [Ames Laboratory and Iowa State University; Lumsden, Mark D [ORNL; Budko, S L [Ames Laboratory and Iowa State University; Canfield, P. C. [Ames Laboratory; Goldman, A. I. [Ames Laboratory and Iowa State University; Mcqueeney, R J [Ames Laboratory and Iowa State University; Tucker, G. S. [Ames Laboratory and Iowa State University

2012-01-01T23:59:59.000Z

412

Post-Deposition Induced Conductivity in Pulsed Laser Irradiated Metal Doped Zinc Oxide Films  

DOE Green Energy (OSTI)

The optical and electrical properties of doped solution-deposited and rf sputter-deposited thin metal oxide films were investigated following post deposition pulsed laser irradiation. Solution deposited films were annealed at 450 ºC. Following the heating regiment, the transparent metal oxide films were subjected to 355 nm pulsed Nd:YAG laser irradiation (4 nsec pulsewidth) at fluences between 5 and 150 mJ/cm2. Irradiation times at pulse frequencies of 30 Hz ranged from seconds to tens of minutes. Film densification, index change and a marked increase in conductivity were observed following irradiation in air and under vacuum of Al:ZnO (AZO), Ga:ZnO (GZO), and In:ZnO (IZO) films deposited on silica substrates. Despite the measured increase in conductivity, all films continued to show high transparency on the order of 90% at wavelengths from the band edge well into the near infrared region of the spectrum. Laser energies required for turning on the conductivity of these films varied depending upon the dopant. Irradiations in air yielded resistivity measurements on the order of 16 ?.cm. Resistivities of films irradiated under vacuum were on the order of 0.1 ?.cm. The increase in conductivity can be attributed to the formation of oxygen vacancies and subsequent promotion of free carriers into the conduction band. All irradiated films become insulating after around 24 hours. Oxygen atoms in air become reduced by electrons in the metal conduction band and diffuse into the vacancies in the lattice. The rate of this reduction process depends on the type of dopant. This work also sheds light on the damage threshold, correlating the optical properties with the presence of free carriers that have been introduced into the conduction band. All films were characterized by means of UV-VIS-NIR transmission spectroscopy, visible and UV Raman spectroscopy and Hall measurements. Analysis of interference fringes in measured transmission spectra allowed film density and refractive index to be evaluated while the Raman measurements showed an increase in LO mode intensity with respect to the TO mode intensity as the films became more conducting. Results of this study are not only important for the continued development of transparent conducting oxide films that find use in photovoltaic cells and solid state lighting modules, but also provide evidence for the role of free carriers in initiating the laser damage process in these wide bandgap metal oxide films.

Wang, Lisa J.; Exarhos, Gregory J.

2009-12-03T23:59:59.000Z

413

Features of the charge-transport mechanism in layered Bi{sub 2}Te{sub 3} single crystals doped with chlorine and terbium  

Science Conference Proceedings (OSTI)

The temperature dependences (T = 5-300 K) of the resistivity in the plane of layers and in the direction perpendicular to the layers, as well as the Hall effect and the magnetoresistance (H < 80 kOe, T = 0.5-4.2 K) in Bi{sub 2}Te{sub 3} single crystals doped with chlorine and terbium, are investigated. It is shown that the doping of Bi{sub 2}Te{sub 3} with terbium atoms results in p-type conductivity and in increasing hole concentration. The doping of Bi{sub 2}Te{sub 3} with chlorine atoms modifies also the character of its conductivity instead of changing only the type from p to n. In the temperature dependence of the resistivity in the direction perpendicular to layers, a portion arises with the activation conductivity caused by the hopping between localized states. The charge-transport mechanism in Bi{sub 2}Te{sub 3} single crystals doped with chlorine is proposed.

Abdullaev, N. A., E-mail: anadir@azintex.com; Abdullaev, N. M.; Aliguliyeva, H. V.; Kerimova, T. G.; Mehdiyev, G. S. [National Academy of Sciences of Azerbaijan, Abdullaev Institute of Physics (Azerbaijan); Nemov, S. A. [St. Petersburg State Polytechnic University (Russian Federation)

2011-01-15T23:59:59.000Z

414

Method for sputtering a PIN microcrystalline/amorphous silicon semiconductor device with the P and N-layers sputtered from boron and phosphorous heavily doped targets  

DOE Patents (OSTI)

A silicon PIN microcrystalline/amorphous silicon semiconductor device is constructed by the sputtering of N, and P layers of silicon from silicon doped targets and the I layer from an undoped target, and at least one semi-transparent ohmic electrode.

Moustakas, Theodore D. (Annandale, NJ); Maruska, H. Paul (Annandale, NJ)

1985-04-02T23:59:59.000Z

415

PROCEEDINGS O F THE IEEE, VOL.56, NO. 1, JANUARY196837 [`I J. J. Wysocki,"Lithium-doped radiation-resistant silicon solar  

E-Print Network (OSTI)

,"Lithium-doped radiation-resistant silicon solar cells," IEEE Trans. Nuclear Science. vol.NS-13, pp. 168-173, December 1966 damagein semiconductorsXI1: Effects ofhighenergy electrons in silicon and silicon solar cells," Contract NAS 5-3805, May 25, 1966. 14] R. V. Tauke, "Thermal annealing of irradiated n-on-p silicon solar cells

Teich, Malvin C.

416

Effect of Nickel Substitution on Defect Chemistry, Electrical Properties, and Dimensional Stability of Calcium-Doped Yttrium Chromite  

SciTech Connect

The effect of nickel substitution on defect chemistry, electrical properties, and dimensional stability of calcium-doped yttrium chromite was studied for use as an interconnect material in high temperature solid oxide fuel cells (SOFCs). The compositions of Y0.8Ca0.2Cr1-xNixO3±? (x=0-0.15), prepared using the glycine nitrate process, showed single phase orthorhombic perovskite structures over a wide range of oxygen partial pressures (10^-17 atm ? pO2 ? 0.21 atm). X-ray diffraction (XRD) analysis indicated that most of the nickel ions replacing chromium ions are divalent and act as acceptor dopants, leading to a substantial increase in conductivity. In particular, the conductivity at 900 degree C in air increased from 10 S/cm to 34 S/cm with 15% nickel substitution, and an increase in charge carrier density was confirmed by Seebeck measurements. A point defect model was derived, and the relationship between electrical conductivity and oxygen partial pressure was successfully fitted into the proposed model. The defect modeling results indicated that nickel substitution improves the stability of calcium-doped yttrium chromite toward reduction and suppresses the oxygen vacancy formation, which results in significantly increased electrical conductivity in reducing environment. The electrical conductivity of Y0.8Ca0.2Cr0.85Ni0.15O3±? at 900 degree C in reducing atmosphere (pO2=10^-17 atm) was 5.8 S/cm, which was more than an order of magnitude higher than that of Y0.8Ca0.2CrO3±? (0.2 S/cm). Improved stability in reducing atmosphere was further confirmed by dilatometry measurements showing reduced isothermal "chemical" expansion, and the isothermal expansion in reducing atmosphere (pO2=10^-17 atm) at 900 degree C decreased from 0.07% for Y0.8Ca0.2CrO3±? to 0.03% for Y0.8Ca0.2Cr0.85Ni0.15O3±?. Based on these results, enhanced electrical performance and mechanical integrity is expected with nickel substitution on calcium-doped yttrium chromite in SOFC operating conditions.

Yoon, Kyung J.; Stevenson, Jeffry W.; Marina, Olga A.

2011-06-30T23:59:59.000Z

417

Nanocrystals Embedded Zirconium-doped Hafnium Oxide High-k Gate Dielectric Films  

E-Print Network (OSTI)

Nanocrystals embedded zirconium-doped hafnium oxide (ZrHfO) high-k gate dielectric films have been studied for the applications of the future metal oxide semiconductor field effect transistor (MOSFET) and nonvolatile memory. ZrHfO has excellent gate dielectric properties and can be prepared into MOS structure with a low equivalent oxide thickness (EOT). Ruthenium (Ru) modification effects on the ZrHfO high-k MOS capacitor have been investigated. The bulk and interfacial properties changed with the inclusion of Ru nanoparticles. The permittivity of the ZrHfO film was increased while the energy depth of traps involved in the current transport was lowered. However, the barrier height of titanium nitride (TiN)/ZrHfO was not affected by the Ru nanoparticles. These results can be important to the novel metal gate/high-k/Si MOS structure. The Ru-modified ZrHfO gate dielectric film showed a large breakdown voltage and a long lifetime. The conventional polycrystalline Si (poly-Si) charge trapping layer can be replaced by the novel floating gate structure composed of discrete nanodots embedded in the high-k film. By replacing the SiO2 layer with the ZrHfO film, promising memory functions, e.g., low programming voltage and long charge retention time, can be expected. In this study, the ZrHfO high-k MOS capacitors that separately contain nanocrystalline ruthenium oxide (nc-RuO), indium tin oxide (nc-ITO), and zinc oxide (nc-ZnO) have been successfully fabricated by the sputtering deposition method followed with the rapid thermal annealing process. Material and electrical properties of these kinds of memory devices have been investigated using analysis tools such as XPS, XRD, and HRTEM; electrical characterizations such as C-V, J-V, CVS, and frequency-dependent measurements. All capacitors showed an obvious memory window contributed by the charge trapping effect. The formation of the interface at the nc-RuO/ZrHfO and nc-ITO/ZrHfO contact regions was confirmed by the XPS spectra. Charges were deeply trapped to the bulk nanocrystal sites. However, a portion of holes were loosely trapped at the nanocrystal/ZrHfO interface. Charges trapped to the different sites lead to different detrapping characteristics. For further improving the memory functions, the dual-layer nc-ITO and -ZnO embedded ZrHfO gate dielectric stacks have been fabricated. The dual-layer embedded structure contains two vertically-separated nanocrystal layers with a higher density than the single-layer embedded structure. The critical memory functions, e.g., memory window, programming efficiency, and charge retention can be improved by using the dual-layer nanocrystals embedded floating gate structure. This kind of gate dielectric stack is vital for the next-generation nonvolatile memory applications.

Lin, Chen-Han

2011-08-01T23:59:59.000Z

418

Synthesis of Room-Temperature Ferromagnetic Cr-doped TiO?(110) Rutile Single Crystals using Ion Implantation  

SciTech Connect

Ferromagnetic Cr-doped rutile TiO? single crystals were synthesized by high-temperature ion implantation. The associated structural, compositional and magnetic properties were studied by x-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, proton induced x-ray emission, x-ray diffraction, Cr K- and L-shell near-edge x-ray absorption spectroscopy, and vibrating sample magnetometry. Cr was distributed uniformly to the depth of about 300 nm with an average concentration of ~1 at. %. The samples are semiconducting and ferromagnetic as implanted, with a saturation magnetization of 0.29???B/Cr atom at room temperature. Cr is in a formal oxidation state of +3 throughout the implanted region, and no CrO? is detected.

Shutthanandan, V.; Thevuthasan, Suntharampillai; Droubay, Timothy; Heald, Steve M.; Engelhard, Mark H.; McCready, David E.; Chambers, Scott A.; Nachimuthu, Ponnusamy; Mun, B. S.

2006-01-01T23:59:59.000Z

419

Detection of charge transfer processes in Cr-doped SrTiO{sub 3} single crystals  

SciTech Connect

An insulator-to-metal transition is observed in Cr-doped SrTiO{sub 3} single crystals upon extended exposure to a high electric field, namely, electroconditioning (EC). Electron paramagnetic resonance (EPR) and transport measurements under laser irradiation show anticorrelation between the Cr{sup 3+} EPR signal and the electrical current. This proves that the Cr{sup 3+} ions are responsible for the photocurrent that initiates the EC process. We observe the presence of Cr{sup 3+}/Cr{sup 4+} mixed valencies in the bulk in the conducting state. The EPR characterization of the spectra in the conducting state excludes the possibility of a Cr{sup 3+}-oxygen vacancy complex in the bulk as a result of the EC.

La Mattina, F. [Physik-Institut der Universitaet Zuerich, Winterthurerstr. 190, CH-8057 Zuerich (Switzerland); IBM Research, Zurich Research Laboratory, Saeumerstr. 4, CH-8803 Rueschlikon (Switzerland); Bednorz, J. G.; Alvarado, S. F. [IBM Research, Zurich Research Laboratory, Saeumerstr. 4, CH-8803 Rueschlikon (Switzerland); Shengelaya, A. [Physics Institute of Tbilisi State University, Chavchavadze 3, GE-0128, Tbilisi (Georgia); Keller, H. [Physik-Institut der Universitaet Zuerich, Winterthurerstr. 190, CH-8057 Zuerich (Switzerland)

2008-07-14T23:59:59.000Z

420

One-photon band gap engineering of borate glass doped with ZnO for photonics applications  

SciTech Connect

Lithium tungsten borate glass of the composition (0.56-x)B{sub 2}O{sub 3}-0.4Li{sub 2}O-xZnO-0.04WO{sub 3} (0 {<=}x{<=} 0.1 mol. %) is prepared for photonics applications. The glass is doped with ZnO to tune the glass absorption characteristics in a wide spectrum range (200-2500 nm). Chemical bond approach, including chemical structure, electronegativity, bond ionicity, nearest-neighbor coordination, and other chemical bonding aspect, is used to analyze and to explain the obtained glass properties such as: transmittance, absorption, electronic structure parameters (bandgap, Fermi level, and Urbach exciton-phonon coupling), Wannier free excitons excitation (applying Elliott's model), and two-photon absorption coefficient as a result of replacement of B{sub 2}O{sub 3} by ZnO.

Abdel-Baki, Manal [Glass Department, National Research Centre, Dokki 12311 Giza (Egypt); Abdel-Wahab, Fathy A.; El-Diasty, Fouad [Physics Department, Faculty of Science, Ain Shams University, Abbasia, 11566 Cairo (Egypt)

2012-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "doping dual-gated bilayer" from the National Library of EnergyBeta (NLEBeta).
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421

Fluorescence properties and electron paramagnetic resonance studies of {gamma}-irradiated Sm{sup 3+}-doped oxyfluoroborate glasses  

Science Conference Proceedings (OSTI)

The permanent photoinduced valence manipulation of samarium doped oxyfluoroborate glasses as a function of {gamma}-ray irradiation has been investigated using a steady-state fluorescence and electron paramagnetic resonance techniques. An increase in SrF{sub 2} content in the glass led to the red shift of the peaks in as prepared glass, while in irradiated glasses this led to the decrease in defect formation as well as increase in photoreduction of Sm{sup 3+} to Sm{sup 2+} ion. The energy transfer mechanism of induced permanent photoreduction of Sm{sup 3+} to Sm{sup 2+} ions in oxyfluoroborate glasses has been discussed. The decay analysis shows exponential behavior before irradiation and non-exponential behavior after irradiation. The energy transfer in irradiated glasses increases with the increase in SrF{sub 2} content in the glass and also with the irradiation dose.

Babu, B. Hari; Ravi Kanth Kumar, V. V. [Department of Physics, Pondicherry University, Kalapet, Puducherry-605 014 (India)

2012-11-01T23:59:59.000Z

422

Mg acceptor doping of In{sub 2}O{sub 3} and overcompensation by oxygen vacancies  

Science Conference Proceedings (OSTI)

Mg-doped indium oxide (In{sub 2}O{sub 3}) thin films were grown by plasma-assisted molecular beam epitaxy with Mg-concentrations ranging from 10{sup 17} to 6 Multiplication-Sign 10{sup 20} cm{sup -3}. In this concentration range Mg was incorporated into In{sub 2}O{sub 3} without discernable impediment nor formation of secondary phases. Despite the role of Mg as acceptor, the films were n-type conductive in the as-grown state or after annealing in vacuum. For Mg-concentrations well in excess of the unintentional donor concentration annealing in oxygen resulted in semi-insulating films without detectable p-type conductivity. These results strongly suggest oxygen vacancies to act as shallow donors in In{sub 2}O{sub 3} that can overcompensate the Mg acceptors.

Bierwagen, Oliver; Speck, James S. [Department of Materials, University of California, Santa Barbara, California 93106 (United States)

2012-09-03T23:59:59.000Z

423

A Large Blue Shift of the Biexciton State in Tellurium Doped CdSe Colloidal Quantum Dots  

E-Print Network (OSTI)

The exciton-exciton interaction energy of Tellurium doped CdSe colloidal quantum dots is experimentally investigated. The dots exhibit a strong Coulomb repulsion between the two excitons, which results in a huge measured biexciton blue shift of up to 300 meV. Such a strong Coulomb repulsion implies a very narrow hole wave function localized around the defect, which is manifested by a large Stokes shift. Moreover, we show that the biexciton blue shift increases linearly with the Stokes shift. This result is highly relevant for the use of colloidal QDs as optical gain media, where a large biexciton blue shift is required to obtain gain in the single exciton regime. The progress in chemical synthesis of colloidal quantum dots, provides a way to produce high quantum yield nanocrystals out of a variety of substances, and allows control over their size, shape and composition. Because of the strong charge confinement within the dots, their electronic excitation

Assaf Avidan; Dan Oron

2008-01-01T23:59:59.000Z

424

Electrochemical studies of Mg-doped Li{sub 4}Ti{sub 5}O{sub 12} anodes.  

DOE Green Energy (OSTI)

Commercial lithium-ion batteries use carbon as the material of choice for the anode. However, because lithiated carbon has a voltage very close to the potential of metallic lithium, there are concerns about the safety of fully-charged carbon electrodes. The safety issue can be addressed by using a material that intercalates lithium at a higher voltage. A promising material is the lithium-titanium-oxide spinel material Li{sub 4}Ti{sub 5}O{sub 12} which can accommodate 3 Li{sup +} ions per formula unit (corresponding to 175 mAh/g) in a two-phase reaction at approximately 1.5 V versus lithium. One of the drawbacks of this system is that the end-member Li{sub 4}Ti{sub 5}O{sub 12} is electronically insulating, which limits electron transfer at the electrode surface. By doping this material with magnesium, Li{sub 4{minus}x}Mg{sub x}Ti{sub 5}O{sub 12}, we introduced mixed-valent Ti{sup 4+}/Ti{sup 3+} into the stoichiometric spinel structure and thereby increased the electronic conductivity by several orders of magnitude without sacrificing electrochemical performance. In this presentation we will provide data on the extent of the solid solution in Li{sub 4{minus}x}Mg{sub x}Ti{sub 5}O{sub 12}, the variation of electronic conductivity as a function of dopant concentration and the rate capability of the doped material.

Chen, C. H.; Jansen, A. N.; Vaughey, J.

1999-07-19T23:59:59.000Z

425

Irradiation-induced reduction and luminescence properties of Sm{sup 2+} doped in BaBPO{sub 5}  

SciTech Connect

Usually, Sm{sup 2+} ions could be reduced by heating the materials in reducing atmospheres. Exposure to ionizing radiations is also known to cause Sm{sup 3+}{yields}Sm{sup 2+} conversion. In this work, BaBPO{sub 5} doped with the samarium ion was prepared by high temperature solid-state reaction. Sm{sup 2+} ions were obtained by two different reduction methods, i.e., heating in H{sub 2} reduced atmosphere and X-ray irradiation. The measurements of X-ray diffraction (XRD), and scanning electron microscope (SEM) were investigated. It is found that the conversion of Sm{sup 3+}{yields}Sm{sup 2+} is very efficient in BaBPO{sub 5} hosts after X-ray irradiation. Sm{sup 2+} ions under these two reduction methods exhibit different characteristics that were studied by measurements of luminescence and decay. The results showed that the luminescence properties of Sm{sup 2+} ions in BaBPO{sub 5} were highly dependent on the sample preparation conditions. - Graphical abstract: The Sm doped in BaBPO{sub 5} as-prepared in air contains only Sm{sup 3+} ions and shows its fluorescence bands due to the {sup 4}G{sub 5/2} to {sup 6}H{sub 5/2}, {sup 6}H{sub 7/2}, {sup 6}H{sub 9/2}, and {sup 6}H{sub 11/2} transitions (a) under the excitation of 488 nm Ar{sup +}-ion laser. The emission spectra of the samples after X-ray subsequentially irradiations are characteristic of Sm{sup 2+} transitions between the energy levels of 4f{sup 6} electronic configurations (b). It is found that the conversion of Sm{sup 3+}{yields}Sm{sup 2+} is very efficient in BaBPO{sub 5} hosts after X-ray irradiation.

Huang Yanlin [School of Material Engineering, Soochow University, 178 GanJiang East Road, Suzhou 215021 (China)], E-mail: huangyanlin@hotmail.com; Jang, Kiwan [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of)], E-mail: kwjang@changwon.ac.kr; Zhao Wanxue [School of Material Engineering, Soochow University, 178 GanJiang East Road, Suzhou 215021 (China); Cho, Eunjin; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Wang Xigang; Qin Dake; Zhang Ying; Jiang Chanfang [School of Material Engineering, Soochow University, 178 GanJiang East Road, Suzhou 215021 (China); Seo, Hyo Jin [Department of Physics, Pukyong National University, Daeyeon 3-Dong 599-1, Pusan 608-737 (Korea, Republic of)

2007-12-15T23:59:59.000Z

426

Electron mobility and drift velocity in selectively doped InAlAs/InGaAs/InAlAs heterostructures  

Science Conference Proceedings (OSTI)

An increase in the electron mobility and drift velocity in high electric fields in quantum wells of selectively doped InAlAs/InGaAs/InAsAs heterostructures is obtained experimentally via controlling the composition of semiconductors forming the interface. The electron mobility at the interface in the In{sub 0.8}Ga{sub 0.2}As/In{sub 0.7}Al{sub 0.3}As metamorphic structure with a high molar fraction of In (0.7-0.8) is as high as 12.3 Multiplication-Sign 10{sup 3} cm{sup 2} V{sup -1} s{sup -1} at room temperature. An increase in the electron mobility by a factor of 1.1-1.4 is attained upon the introduction of thin (1-3 nm) InAs layers into a quantum well of selectively doped In{sub 0.53}Ga{sub 0.47}As/In{sub 0.52}Al{sub 0.48}As heterostructures. A maximal drift velocity attains 2.5 Multiplication-Sign 10{sup 7} cm/s in electric fields of 2-5 kV/cm. The threshold field F{sub th} for the intervalley {Gamma}-L electron transfer (the Gunn effect) in the InGaAs quantum well is higher than in the bulk material by a factor of 2.5-3. The effect of two- to threefold decrease in the threshold field F{sub th} in the InGaAs quantum well is established upon increasing the molar fraction of In in the InAlAs barrier, as well as upon the introduction of thin InAs inserts into the InGaAs quantum well.

Vasil'evskii, I. S., E-mail: pozela@pfi.lt; Galiev, G. B.; Klimov, E. A. [MEPHI National Nuclear Research University (Russian Federation); Pozela, K.; Pozela, J.; Juciene, V.; Suziedelis, A.; Zurauskiene, N.; Kersulis, S.; Stankevic, V. [Center for Physical Sciences and Technology, Semiconductor Physics Institute (Lithuania)

2011-09-15T23:59:59.000Z

427

Defect energetics and electronic structures of As-doped p-type ZnO crystals: A first-principles study  

E-Print Network (OSTI)

First-principles calculations based on density functional theory have been carried out to understand the mechanism of fabricating As-doped p-type ZnO semiconductors. It has been confirmed that AsZn-2VZn complex is the most plausible acceptor among several candidates for p-type doping by computing the formation and ionization energies. The electronic band structures and atomic-projected density of states of AsZn-2VZn defect complex-contained ZnO bulks have been computed. The acceptor level in AsZn-2VZn band structure has found to be 0.12 eV, which is in good agreement with the experimental ionization energy (0.12 ~ 0.18 eV). The hybridization among O 2p, Zn 3d and As 4s states has been observed around the valence band maximum.

Yu, Chol-Jun; Ri, Son-Guk; Kim, Myong-Il; Im, Song-Jin

2013-01-01T23:59:59.000Z

428

Improvement of Vertical Diode Properties by N-type Plasma Doping for Low-Power Phase Change Non-Volatile Memory (NVM)  

SciTech Connect

Using PH{sub 3} N-type plasma doing (PLAD), the device characteristics of high performance vertical switch diode for 50 nm phase-change NVM have been studied. Compared to the conventional beam line ion implantation, there are improvements of diode breakdown voltage (B.V.) and isolation B.V., respectively 20% and 41% by N-type PLAD doping due to the higher doping level and shallower profile in N+ region. It also shows excellent off-leakage properties less than 10 pA/cell without decreasing the Ion. From the results of this study, N-type PLAD has been demonstrated to be effective for vertical diode electrical properties as well as for high productivity.

Lee, Min Yong; Lee, H. S.; Ki, Y. J.; Sohn, Y. S.; Kang, H. S. [R and D Division, Hynix Semiconductor Inc., San 136-1, Ami-ri, Bubal-eub, Ichon-si, kyoungki-do 467-701 (Korea, Republic of); Oh, C. Y.; Park, J. W. [Varian Korea Ltd., 433-1 Mogok-dong Pyeongtaek-si Kyoungki-do 459-040 (Korea, Republic of); Jo, S. H. [Varian Semiconductor Equipment Associates Inc., 35 Dory Road, Gloucester, MA 01930 (United States)

2011-01-07T23:59:59.000Z

429

Observation of Orbital Ordering and Jahn-Teller Distortions Supporting the Wigner-crystal Model in Highly Dopes Bi{1-x}Ca{x}MnO{3}  

SciTech Connect

We report on the experimental characterization of orbital ordering and the associated lattice distortions in highly doped Bi{sub 1-x}Ca{sub x}MnO{sub 3}. Resonant x-ray diffraction was used at the Mn L-edge for the direct observation of the ordered localized states, and at the Mn K-edge for the sensitivity to the distortions of the manganese-oxygen octahedra. The orbital ordering on Mn atoms was directly observed at x=0.69; the analysis and the numerical simulations of the K-edge spectra allow us to characterize the pattern of the distorted octahedra at x = 4/5. These observations support the Wigner-crystal-type model at both dopings; the bi-stripe model is ruled out at x = 0.69.

Grenier,S.; Kiryukhin, V.; Cheong, S.; Kim, B.; Hill, J.; Thomas, K.; Tonnerre, J.; Joly, Y.; Staub, U.; Scagnoli, V.

2007-01-01T23:59:59.000Z

430

Doped Yttrium Chromite-Ceria Composite as a Redox-Stable and Sulfur-Tolerant Anode for Solid Oxide Fuel Cells  

Science Conference Proceedings (OSTI)

A Ca- and Co-doped yttrium chromite (YCCC) - samaria-doped ceria (SDC) composite was studied in relation to a potential use as a solid oxide fuel cell (SOFC) anode material. Tests performed using the yttria-stabilized zirconia (YSZ) electrolyte-supported cells revealed that the electrocatalytic activity of the YCCC-SDC anode towards hydrogen oxidation at 800 C was comparable to that of the Ni-YSZ anode. In addition, the YCCC-SDC anode exhibited superior sulfur tolerant characteristics showing less than 10% increase in a polarization resistance, fully reversible, upon exposure to 20 ppm H2S at 800 C. No performance degradation was observed during multiple reduction-oxidation (redox) cycles when the anode was intentionally exposed to the air environment followed by the reduction in hydrogen. The redox tolerance of the YCCC-SDC anode was attributed to the dimensional and chemical stability of the YCCC exhibiting minimal isothermal chemical expansion upon redox cycling.

Yoon, Kyung J.; Coyle, Christopher A.; Marina, Olga A.

2011-12-11T23:59:59.000Z