National Library of Energy BETA

Sample records for tran si tion

  1. The SpallaTion

    Energy Savers [EERE]

    SpallaTion neuTron Source projecT When the Department of Energy (DOE) set out in the 1990s to develop a neutron scattering research facility that was ten times more powerful than the state of the art, the concept for the project that it chose was as ambitious as the scientific capability it sought to deliver. The Spallation Neutron Source (SNS) Project called for unprecedented collaboration among six national laboratories as well as significant research and development that would push the

  2. CUSSSFIC4TION CMUXLLq

    Office of Legacy Management (LM)

    CUSSSFIC4TION CMUXLLq RITE AUG 1 7 1962 Fcx the Atomic. Energy Commisaion~ Chief. Declaseifle@tlon Brar\qh F-mm A. B. Grsaingsr (Other ends tifmtioel) The die wae foutq3 to workvery satiafactorilywiti thlanew Qpeof incert, andncm,of tbepmvLouedsfeotaofeoo+tH&' iOitYwaslmd. D&e& ._: . . ..YG ~Kl.3. i>ro;rid3 -&I:: clcsuro on bct.k.mds of the .plece m & Die #l, is also to be tried outoo 4zgust22. Barr~l~or~~~Die~~hadalaobeenawlLfiedta' plwidesd~do~-

  3. CLASSIFICdTION CAWXL~ DAm

    Office of Legacy Management (LM)

    CLASSIFICdTION CAWXL~ DAm NAR 6 1969 For the Atomic EhergY hDh=+= ,' ROBERT L JACKSON /(\' t' for the Chief, Declassification B~Jx~

  4. Transformation of cis- and trans-2,3-dimethyloxiranes on a Pd/SiO{sub 2} catalyst

    SciTech Connect (OSTI)

    Fasi, A.; Notheisz, F.; Bartok, M.

    1997-04-01

    The transformation of cis- and trans-2,3-dimethyloxiranes on a Pd/SiO{sub 2} catalyst, leading to the formation of 2-butanone and 2-butanol, was studied in hydrogen and deuterium atmosphere. The effect of hydrogen and deuterium atmosphere. The effect of hydrogen pressure (1.3-100 kPa) and temperature (323-423 K) on the reaction rate was also measured. The transformation of the two stereoisomers involves different mechanisms. In the case of the cis-isomer, hydrogen participates in the cleavage of the C-O bond and different surface species belong to the two products. In the case of the trans-isomer, ring opening by hydrogen (the formation of 2-butanol) is less significant and the main reaction is intramolecular migration leading to the formation of 2-butanone. Considering the geometry of the adsorbed species, cis-2,3-dimethyloxirane is most probably adsorbed on the surface of the Pd catalyst in a planar manner, while the adsorption of the trans-isomer is intermediate between edgewise and planar adsorption model. 18 refs., 3 figs., 3 tabs.

  5. UTICA 4, NEW YORK COFIPOR~TION

    Office of Legacy Management (LM)

    DROf fORGE & TOOL UTICA 4, NEW YORK COFIPOR~TION PHONE 3- 2331 July 5, 1955 ?:r. E. J. Block Director of Production Division United Staton Atomic ::norgy Commission Yiashington, D. C. Dear Xr. 1310~1~: Xe had a visit last Thursday from Kr. R. C. Sale11 of the: Atomic Energy Commission who inspected our vacuum melting facilities. EIz suggested that we should get in touch with you and that you r+ht be interested in the use of our facilities for the i>roduction of uranium fuel elements. Xe

  6. SANDIA COKPOK4TION SANDIA BASE, .QLDUQUERQUE. N. M.

    Office of Legacy Management (LM)

    SANDIA COKPOK4TION SANDIA BASE, .QLDUQUERQUE. N. M. To : DISTRIBUTION Re: Disposition of t h e Shoal S i t e Attached herewith i s a study which has been made s w g e s t i n g p o s s i b l e f u r t h e r uses of t h e Shoal S i t e . I - ! e have a l s o b r i e f l y described how permanent d i s p o s i t i o n might be made. The study has been made with t h e hope t h a t it w i l l evolce f u r t h e r considerc~tion of t h e s i t e and l e a d t o a plan f o r continued use and eventual

  7. si

    Office of Legacy Management (LM)

    si :ri; .-.- ..~ -- The Orrk R&e Ins@@& for Science aud EduWion (ORISE) was established by the U.S. Department of Energy to undertake national aud international programs in science and engineering education, training and management systems, energy and environment systems, and medical sciences. ORISE and its programs are operated by Oak Ridge Associated Universities (ORAU) through a management and operating contract with the U.S. Department of Energy. Established in 1946, ORAU is a

  8. Trans Tech Green Power | Open Energy Information

    Open Energy Info (EERE)

    Trans Tech Green Power Jump to: navigation, search Name: Trans Tech Green Power Place: India Sector: Biomass Product: Plans to develop biomass projects in Rajasthan. References:...

  9. WebTrans Update - August 31, 2015

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Notices Rates Standards of Conduct Tariff TF Web Based Training Notice: WebTrans Update Posted Date: 8312015 BPAT is deploying a minor change to Production webTrans in...

  10. WebTrans Update - September 9, 2015

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Notices Rates Standards of Conduct Tariff TF Web Based Training Notice: WebTrans Update Posted Date: 992015 BPAT is deploying a change to Production webTrans today...

  11. Trans India Acquisition Corporation | Open Energy Information

    Open Energy Info (EERE)

    India Acquisition Corporation Jump to: navigation, search Name: Trans-India Acquisition Corporation Place: Delaware Sector: Solar Product: Blank check company to be merged with...

  12. TransWest Old | Open Energy Information

    Open Energy Info (EERE)

    Old Jump to: navigation, search NEPA Document Collection for: TransWest Old EIS NEPA name unknown General NEPA Document Info Environmental Analysis Type EIS Applicant Not Provided...

  13. IRAK4 Dimerization and Trans-Autophosphorylation Are Induced...

    Office of Scientific and Technical Information (OSTI)

    IRAK4 Dimerization and Trans-Autophosphorylation Are Induced by Myddosome Assembly Citation Details In-Document Search Title: IRAK4 Dimerization and Trans-Autophosphorylation Are ...

  14. EIS-0139: Trans-Alaska Gas System

    Broader source: Energy.gov [DOE]

    This EIS analyzes the Yukon Pacific Corporation's proposed construction of the Trans-Alaska Gas System (TAGS), a 796.5-mile long, 36-inch diameter pipeline to transport high-pressured natural gas between Prudhoe Bay and a tidewater terminal and liquefied natural gas plant near Anderson Bay, Alaska.

  15. New England Hydro-Trans Corp | Open Energy Information

    Open Energy Info (EERE)

    Hydro-Trans Corp Jump to: navigation, search Name: New England Hydro-Trans Corp Place: New Hampshire Phone Number: 1.800.661.3805 Website: www.transcanada.comindex.html Twitter:...

  16. New England Hydro-Tran Elec Co | Open Energy Information

    Open Energy Info (EERE)

    New England Hydro-Tran Elec Co Jump to: navigation, search Name: New England Hydro-Tran Elec Co Place: Massachusetts Phone Number: 860 729 9767 Website: www.nehydropower.com...

  17. Infrared absorption of trans-1-chloromethylallyl and trans-1-methylallyl radicals produced in photochemical reactions of trans-1,3-butadiene and C Script-Small-L {sub 2} in solid para-hydrogen

    SciTech Connect (OSTI)

    Bahou, Mohammed; Wu, Jen-Yu; Tanaka, Keiichi; Lee, Yuan-Pern

    2012-08-28

    The reactions of chlorine and hydrogen atoms with trans-1,3-butadiene in solid para-hydrogen (p-H{sub 2}) were investigated with infrared (IR) absorption spectra. When a p-H{sub 2} matrix containing C Script-Small-L {sub 2} and trans-1,3-butadiene was irradiated with ultraviolet light at 365 nm, intense lines at 650.3, 809.0, 962.2, 1240.6 cm{sup -1}, and several weaker ones due to the trans-1-chloromethylallyl radical, Bullet (CH{sub 2}CHCH)CH{sub 2}C Script-Small-L , appeared. Observed wavenumbers and relative intensities agree with the anharmonic vibrational wavenumbers and IR intensities predicted with the B3PW91/6-311++g(2d, 2p) method. That the C Script-Small-L atom adds primarily to the terminal carbon atom of trans-1,3-butadiene is in agreement with the path of minimum energy predicted theoretically, but in contrast to the reaction of C Script-Small-L + propene in solid p-H{sub 2}[J. Amicangelo and Y.-P. Lee, J. Phys. Chem. Lett. 1, 2956 (2010)] in which the addition of C Script-Small-L to the central C atom is favored, likely through steric effects in a p-H{sub 2} matrix. A second set of lines, intense at 781.6, 957.9, 1433.6, 2968.8, 3023.5, 3107.3 cm{sup -1}, were observed when the UV-irradiated C Script-Small-L {sub 2}/trans-1,3-butadiene/p-H{sub 2} matrix was further irradiated with IR light from a SiC source. These lines are assigned to the trans-1-methylallyl radical, Bullet (CH{sub 2}CHCH)CH{sub 3}, produced from reaction of 1,3-butadiene with a H atom resulted from the reaction of C Script-Small-L atoms with solid p-H{sub 2} exposed to IR radiation.

  18. EA-262 TransCanada Power Marketing Ltd | Department of Energy

    Energy Savers [EERE]

    TransCanada Power Marketing Ltd EA-262 TransCanada Power Marketing Ltd Order authorizing TransCanada Power Marketing Ltd to export electric energy to Canada. PDF icon EA-262 TransCanada Power Marketing Ltd More Documents & Publications EA-262-A TransCanada Power Marketing Ltd EA-262-C TransCanada Power Marketing Ltd EA-262-B

  19. Deseret Generation & Tran Coop (Colorado) | Open Energy Information

    Open Energy Info (EERE)

    Coop (Colorado) Jump to: navigation, search Name: Deseret Generation & Tran Coop Place: Colorado Website: www.deseretpower.com Outage Hotline: (801) 619-6500 References: EIA Form...

  20. Coway International TechTrans Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    company with experience in technology transfer in China, specialising in biotech, chemical, energy environment and CDM areas. References: Coway International TechTrans Co...

  1. VTA, SamTrans Look into Future with Bus Demo

    Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (EERE)]

    induction motor for propulsion. Although there are several fuel cell chemistries and configura- tions, PEM is generally recog- nized as the best combination of electrochemistry, operating temperature, and weight for transportation applications. The fuel cell supplies electric current via an inverter to the propulsion motor, which is a proprietary design. This chassis- mounted, three-phase, induction motor is rated at 225 kW (369 horsepower). Hydrogen is stored onboard in eleven 5,000-psi

  2. EA-262-A TransCanada Power Marketing Ltd | Department of Energy

    Energy Savers [EERE]

    A TransCanada Power Marketing Ltd EA-262-A TransCanada Power Marketing Ltd Order authorizing TransCanada Power Marketing Ltd to export electric energy to Canada. PDF icon EA-262-A TransCanada Power Marketing Ltd More Documents & Publications EA-262-C TransCanada Power Marketing Ltd EA-262-B TransCanada Power Marketing Ltd EA-262

  3. EA-262-B TransCanada Power Marketing Ltd | Department of Energy

    Energy Savers [EERE]

    B TransCanada Power Marketing Ltd EA-262-B TransCanada Power Marketing Ltd Order authorizing TransCanada Power Marketing Ltd to export electric energy to Canada. PDF icon EA-262-B TransCanada Power Marketing Ltd More Documents & Publications EA-262-A TransCanada Power Marketing Ltd EA-262-C TransCanada Power Marketing Ltd EA-262

  4. EA-262-C TransCanada Power Marketing Ltd | Department of Energy

    Energy Savers [EERE]

    C TransCanada Power Marketing Ltd EA-262-C TransCanada Power Marketing Ltd Order authorizing TransCanada Power Marketing Ltd to export electric energy to Canada. PDF icon EA-262-C TransCanada Power Marketing Ltd More Documents & Publications Application to export electric energy OE docket No. EA-262-C TransCanada Power Marketing Ltd EA-262-A TransCanada Power Marketing Ltd EA-262-B

  5. TransCanada Power Mktg Ltd (Connecticut) | Open Energy Information

    Open Energy Info (EERE)

    Connecticut Phone Number: 1.800.661.3805 Website: www.transcanada.compowermarke Twitter: @TransCanada Outage Hotline: 1-800-447-8066 References: EIA Form EIA-861 Final Data...

  6. TransCanada Energy Marketing ULC | Open Energy Information

    Open Energy Info (EERE)

    Marketing ULC Jump to: navigation, search Name: TransCanada Energy Marketing ULC Place: California References: EIA Form EIA-861 Final Data File for 2010 - File1a1 EIA Form 861...

  7. Uncertainty quantification methodologies development for storage and trans-

    Office of Scientific and Technical Information (OSTI)

    portation of used nuclear fuel: Pilot study on stress corrosion cracking of canister welds (Technical Report) | SciTech Connect Technical Report: Uncertainty quantification methodologies development for storage and trans- portation of used nuclear fuel: Pilot study on stress corrosion cracking of canister welds Citation Details In-Document Search Title: Uncertainty quantification methodologies development for storage and trans- portation of used nuclear fuel: Pilot study on stress corrosion

  8. EA-216-C TransAlta Energy Marketing (U.S.)Inc. | Department of Energy

    Energy Savers [EERE]

    C TransAlta Energy Marketing (U.S.)Inc. EA-216-C TransAlta Energy Marketing (U.S.)Inc. Order authorizing TransAlta Energy Marketing (U.S.) Inc to export electric energy to Canada. PDF icon EA-216-C TEMUS CN.pdf More Documents & Publications EA-216-B TransAlta Energy Marketing (U.S) Inc

  9. EA-216-B TransAlta Energy Marketing (U.S) Inc | Department of Energy

    Energy Savers [EERE]

    B TransAlta Energy Marketing (U.S) Inc EA-216-B TransAlta Energy Marketing (U.S) Inc Order authorizing TransAlta Energy Marketing (U.S) Inc to export electric energy to Canada. PDF icon EA-216-B TransAlta Energy Marketing (U.S) Inc More Documents & Publications EA-216-C TransAlta Energy Marketing (U.S.)Inc.

  10. Using HyTrans to Study H2 Transition Scenarios

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Using HyTrans to Study H2 Transition Scenarios David Greene & Paul Leiby Oak Ridge National Laboratory Elzbieta Tworek Univ. of Tennessee & StrataG David Bowman Consultant DOE Hydrogen Transition Analysis Workshop January 26, 2006 Washington, DC OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY We will try to cover 4 topics in ½ hour because what we want is your input. 1. What is HyTrans? 2. What can it do? 1. Previous

  11. Application to export electric energy OE docket No. EA-262-C TransCanada

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Power Marketing Ltd | Department of Energy docket No. EA-262-C TransCanada Power Marketing Ltd Application to export electric energy OE docket No. EA-262-C TransCanada Power Marketing Ltd Application from TransCanada Power Marketing Ltd to export electric energy to Canada. PDF icon Application to export electric energy OE docket No. EA-262-C TransCanada Power Marketing Ltd More Documents & Publications EA-262-C TransCanada Power Marketing Ltd EA-262-A TransCanada Power Marketing Ltd

  12. Regulatory Interactions in ProKaryotes from RegTransBase () | Data Explorer

    Office of Scientific and Technical Information (OSTI)

    Regulatory Interactions in ProKaryotes from RegTransBase Title: Regulatory Interactions in ProKaryotes from RegTransBase RegTransBase, a manually curated database of regulatory interactions in prokaryotes, captures the knowledge in published scientific literature using a controlled vocabulary. RegTransBase describes a large number of regulatory interactions reported in many organisms and contains various types of experimental data, in particular: the activation or repression of transcription by

  13. EA-216 TransAlta Energy Marketing (U.S) Inc | Department of Energy

    Energy Savers [EERE]

    TransAlta Energy Marketing (U.S) Inc EA-216 TransAlta Energy Marketing (U.S) Inc Order authorizing TransAlta Energy Marketing (U.S) Inc to export electric energy to Canada. PDF icon EA-216 TransAlta Energy Marketing (U.S) Inc More Documents & Publications EA-232 OGE Energy Resources Inc EA-249 Exelon Generation Company LLC EA-122-A Dynegy Power Marketing, Inc

  14. Trans-Atlantic Workshop on Rare Earth Elements and Other Critical Materials

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    for a Clean Energy Future | Department of Energy Trans-Atlantic Workshop on Rare Earth Elements and Other Critical Materials for a Clean Energy Future Trans-Atlantic Workshop on Rare Earth Elements and Other Critical Materials for a Clean Energy Future Trans-Atlantic Workshop on Rare Earth Elements and Other Critical Materials for a Clean Energy Future PDF icon Trans-Atlantic Workshopon Rare Earth Elements andOther Critical Materials for a Clean Energy Future More Documents &

  15. Application to export electric energy OE Docket No. EA-216-C TransAlta

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy Marketing (U.S) Inc | Department of Energy Inc Application to export electric energy OE Docket No. EA-216-C TransAlta Energy Marketing (U.S) Inc Application from TransAlta Energy Marketing (U.S) Inc to export electric energy to Canada. PDF icon Application to export electric energy OE Docket No. EA-216-C TransAlta Energy Marketing (U.S) Inc More Documents & Publications EA-216-B TransAlta Energy Marketing (U.S) Inc EA-216-C TransAlta Energy Marketing (U.S.)Inc. Application to

  16. SiNode Systems

    Broader source: Energy.gov [DOE]

    SiNode Systems is a battery materials venture developing silicon-graphene anodes for the next generation of lithium-ion batteries. SiNode anodes offer higher battery capacity and faster charging rates, all while being produced via a low cost solution chemistry-based manufacturing process.

  17. Analyzing the Impacts of Policies and Technological Change Using HyTrans |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Analyzing the Impacts of Policies and Technological Change Using HyTrans Analyzing the Impacts of Policies and Technological Change Using HyTrans Presentation by ORNL's David Greene at the 2010 - 2025 Scenario Analysis for Hydrogen Fuel Cell Vehicles and Infrastructure Meeting on August 9 - 10, 2006 in Washington, D.C. PDF icon greene_scenarios_hytrans.pdf More Documents & Publications Integrated Market Modeling of Hydrogen Transition Scenarios with HyTrans Cost and

  18. EIS-0450: TransWest Express Transmission Project; Wyoming, Colorado, Utah,

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Nevada | Department of Energy 0: TransWest Express Transmission Project; Wyoming, Colorado, Utah, and Nevada EIS-0450: TransWest Express Transmission Project; Wyoming, Colorado, Utah, and Nevada Summary This EIS, prepared jointly by DOE's Western Area Power Administration and the Department of the Interior's Bureau of Land Management (Wyoming State Office), evaluates the potential environmental impacts of granting a right-of-way for the TransWest Express Transmission Project and amending

  19. The benzene metabolite trans,trans-muconaldehyde blocks gap junction intercellular communication by cross-linking connexin43

    SciTech Connect (OSTI)

    Rivedal, Edgar Leithe, Edward

    2008-11-01

    Benzene is used at large volumes in many different human activities. Hematotoxicity and cancer-causation as a result of benzene exposure was recognized many years ago, but the mechanisms involved remain unclear. Aberrant regulation of gap junction intercellular communication (GJIC) has been linked to both cancer induction and interference with normal hematopoietic development. We have previously suggested that inhibition of GJIC may play a role in benzene toxicity since benzene metabolites were found to block GJIC, the ring-opened trans,trans-muconaldehyde (MUC) being the most potent metabolite. In the present work we have studied the molecular mechanisms underlying the MUC-induced inhibition of gap junctional communication. We show that MUC induces cross-linking of the gap junction protein connexin43 and that this is likely to be responsible for the induced inhibition of GJIC, as well as the loss of connexin43 observed in Western blots. We also show that glutaraldehyde possesses similar effects as MUC, and we compare the effects to that of formaldehyde. The fact that glutaraldehyde and formaldehyde have been associated with induction of leukemia as well as disturbance of hematopoiesis, strengthens the possible link between the effect of MUC on gap junctions, and the toxic effects of benzene.

  20. Trans beta substituted chlorins and methods of making and using the same

    DOE Patents [OSTI]

    Lindsey, Jonathan S.; Balasubramanian, Thiagarajan

    2003-05-06

    Trans beta substituted chlorins and methods of making the same are disclosed, along with polymers formed from or containing such trans beta substituted chlorins as one or more monomeric units therein, light harvesting rods formed from such polymers, and electrodes carrying such polymers.

  1. A note on trans-Planckian tail effects

    SciTech Connect (OSTI)

    Graef, L.L.; Brandenberger, R.

    2015-09-09

    We study the proposal by Mersini et al. http://dx.doi.org/10.1103/PhysRevD.64.043508 that the observed dark energy might be explained by the back-reaction of the set of tail modes in a theory with a dispersion relation in which the mode frequency decays exponentially in the trans-Planckian regime. The matter tail modes are frozen out, however they induce metric fluctuations. The energy-momentum tensor with which the tail modes effect the background geometry obtains contributions from both metric and matter fluctuations. We calculate the equation of state induced by the tail modes taking into account the gravitational contribution. We find that, in contrast to the case of frozen super-Hubble cosmological fluctuations, in this case the matter perturbations dominate, and they yield an equation of state which to leading order takes the form of a positive cosmological constant.

  2. Application to export electric energy OE Docket No. EA-216-C TransAlta

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy Marketing (U.S) Inc: Federal Register Notice Volume 76, No. 14 - Jan. 21, 2011 | Department of Energy Inc: Federal Register Notice Volume 76, No. 14 - Jan. 21, 2011 Application to export electric energy OE Docket No. EA-216-C TransAlta Energy Marketing (U.S) Inc: Federal Register Notice Volume 76, No. 14 - Jan. 21, 2011 Application from TransAlta Energy Marketing (U.S) Inc to export electric energy to Canada. Federal Register Notice Vol 76 No 14 PDF icon EA-16-C TransAlta Energy

  3. Regulatory Interactions in ProKaryotes from RegTransBase

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Dubchak, Inna; Gelfand, Mikhail

    RegTransBase, a manually curated database of regulatory interactions in prokaryotes, captures the knowledge in published scientific literature using a controlled vocabulary. RegTransBase describes a large number of regulatory interactions reported in many organisms and contains various types of experimental data, in particular: the activation or repression of transcription by an identified direct regulator determining the transcriptional regulatory function of a protein (or RNA) directly binding to DNA or RNA mapping or prediction of binding sites for a regulatory protein characterization of regulatory mutations Currently, the RegTransBase content is derived from about 3000 relevant articles describing over 7000 experiments in relation to 128 microbes. It contains data on the regulation of about 7500 genes and evidence for 6500 interactions with 650 regulators. RegTransBase also contains manually created position weight matrices (PWM) that can be used to identify candidate regulatory sites in over 60 species. (Specialized Interface)

  4. TransCanada Power Mktg Ltd (New Hampshire) | Open Energy Information

    Open Energy Info (EERE)

    Place: New Hampshire Phone Number: 1.800.661.3805 Website: www.transcanada.comindex.html Twitter: @TransCanada Outage Hotline: 1-800-447-8066 References: EIA Form EIA-861 Final...

  5. BPAT webTrans Update to CDE Shared Path Summary - October 9,...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Notices Rates Standards of Conduct Tariff TF Web Based Training Notice: BPAT webTrans Update to CDE Shared Path Summary Posted Date: 1092015 BPAT is deploying a change to...

  6. BPAT webTrans Update to CDE Shared Path Summary - November 5...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Notices Rates Standards of Conduct Tariff TF Web Based Training Notice: BPAT webTrans Update to CDE Shared Path Summary Posted Date: 1152015 BPAT is deploying a change to...

  7. Integrated Market Modeling of Hydrogen Transition Scenarios with HyTrans |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Integrated Market Modeling of Hydrogen Transition Scenarios with HyTrans Integrated Market Modeling of Hydrogen Transition Scenarios with HyTrans Presentation by Paul Leiby of Oak Ridge National Laboratory at the Joint Meeting on Hydrogen Delivery Modeling and Analysis, May 8-9, 2007 PDF icon deliv_analysis_leiby.pdf More Documents & Publications DOE Hydrogen Transition Analysis Workshop Hydrogen Policy and Analyzing the Transition Hydrogen Transition Study

  8. Trans-Atlantic Workshop on Rare Earth Elements and Other Critical Materials

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    for a Clean Energy Future | Department of Energy Trans-Atlantic Workshop on Rare Earth Elements and Other Critical Materials for a Clean Energy Future Trans-Atlantic Workshop on Rare Earth Elements and Other Critical Materials for a Clean Energy Future December 3, 2010 Session A: Setting the Scene - Critical Materials for a Clean Energy Future Diana Bauer, Office of Policy and International Affairs, U.S. Department of Energy, Highlights of the DOE Critical Materials Strategy Antje

  9. Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions...

    Office of Scientific and Technical Information (OSTI)

    Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions Citation Details In-Document Search Title: Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions ...

  10. Si Brilliant Technology Ltd | Open Energy Information

    Open Energy Info (EERE)

    Si Brilliant Technology Ltd Jump to: navigation, search Name: Si-Brilliant Technology Ltd Place: Zhejiang Province, China Sector: Solar Product: Chinese solar-grade polysilicon...

  11. A=17Si (1993TI07)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Si (1993TI07) (Not observed) See (1983ANZQ, 1988WA18, 1992AV03).

  12. SiC Power Module

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    R&D 100 Entry SiC Power Module 2 R&D 100 Entry SiC Power Module Submitting OrganizatiOn Sandia National Laboratories PO Box 5800, MS 1033 Albuquerque, NM 87185-1033 USA Stanley Atcitty Phone: 505-284-2701 Fax: 505-844-2890 satcitt@sandia.gov AFFIRMATION: I affirm that all information submitted as a part of, or supplemental to, this entry is a fair and accurate representation of this product. _____________________________________ Stanley Atcitty JOint Entry Arkansas Power Electronics

  13. Low Activation Joining of SiC/SiC Composites for Fusion Applications: Tape Casting TiC+Si Powders

    SciTech Connect (OSTI)

    Henager, Charles H.; Kurtz, Richard J.; Canfield, Nathan L.; Shin, Yongsoon; Luscher, Walter G.; Mansurov, Jirgal; Roosendaal, Timothy J.; Borlaug, Brennan A.

    2014-03-03

    This work discusses the latest developments in TiC + Si displacement reaction joining at PNNL based on new work to produce tape-cast powders for improved SiC-joints.

  14. TRANS4: a computer code calculation of solid fuel penetration of a concrete barrier. [LMFBR; GCFR

    SciTech Connect (OSTI)

    Ono, C. M.; Kumar, R.; Fink, J. K.

    1980-07-01

    The computer code, TRANS4, models the melting and penetration of a solid barrier by a solid disc of fuel following a core disruptive accident. This computer code has been used to model fuel debris penetration of basalt, limestone concrete, basaltic concrete, and magnetite concrete. Sensitivity studies were performed to assess the importance of various properties on the rate of penetration. Comparisons were made with results from the GROWS II code.

  15. EIS-0450: TransWest Express Transmission Project; Wyoming, Colorado, Utah, and Nevada

    Broader source: Energy.gov [DOE]

    This EIS, prepared jointly by DOE's Western Area Power Administration and the Department of the Interior's Bureau of Land Management (Wyoming State Office), evaluates the potential environmental impacts of granting a right-of-way for the TransWest Express Transmission Project and amending a land use plan. The project consists of an overhead transmission line that would extend approximately 725 miles from south-central Wyoming, through Colorado and Utah. Western proposes to be a joint owner of the project.

  16. Application to Export Electric Energy OE Docket No. EA-216-C TransAlta

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy Marketing (U.S) Inc . Canadian Electrical Association Comments | Department of Energy . Canadian Electrical Association Comments Application to Export Electric Energy OE Docket No. EA-216-C TransAlta Energy Marketing (U.S) Inc . Canadian Electrical Association Comments Protest of the Canadian Electricity Association and the Electric Power Supply Association to Sierra Club's Notice of Intervention and Motion to Intervene in favor of the application to export electric energy OE Docket

  17. Centrotherm SiQ | Open Energy Information

    Open Energy Info (EERE)

    SiQ Jump to: navigation, search Name: Centrotherm SiQ Place: Germany Product: JV company by SolMic and Centrotherm to design and manufacture 'Siemens type' CVD reactors and STC-TCS...

  18. Vehicle Technologies Office Merit Review 2014: Transportation Energy Transition Modeling and Analysis: the LAVE-Trans Model

    Broader source: Energy.gov [DOE]

    Presentation given by Oak Ridge National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about the LAVE-Trans...

  19. Effect of Si substrate on interfacial SiO{sub 2} scavenging in HfO{sub 2}/SiO{sub 2}/Si stacks

    SciTech Connect (OSTI)

    Li, Xiuyan, E-mail: xiuyan@adam.t.u-tokyo.ac.jp; Yajima, Takeaki; Nishimura, Tomonori; Nagashio, Kosuke; Toriumi, Akira [Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656 (Japan)

    2014-11-03

    The scavenging kinetics of an ultra-thin SiO{sub 2} interface layer (SiO{sub 2}-IL) in an HfO{sub 2}/SiO{sub 2}/Si stack is discussed by focusing on the substrate effect in addition to oxygen diffusion. {sup 18}O tracing experiments demonstrate that the O-atom moves from the SiO{sub 2}-IL to the HfO{sub 2} layer during scavenging. SiO{sub 2}-IL scavenging with various substrates (Si, SiC, and sapphire) has been found to be significantly different, which suggests that the Si in the substrate is also necessary to continuously cause the scavenging. Based on these findings and thermodynamic considerations, a kinetic model where oxygen vacancy (V{sub O}) transferred from the HfO{sub 2} reacts with the SiO{sub 2}, which is in contact with the Si-substrate, is proposed for the SiO{sub 2}-IL scavenging.

  20. Propagation of misfit dislocations from buffer/Si interface into Si

    DOE Patents [OSTI]

    Liliental-Weber, Zuzanna; Maltez, Rogerio Luis; Morkoc, Hadis; Xie, Jinqiao

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  1. Low Activation Joining of SiC/SiC Composites for Fusion Applications: Tape Casting TiC+Si Powders

    SciTech Connect (OSTI)

    Henager, Charles H.; Kurtz, Richard J.; Canfield, Nathan L.; Shin, Yongsoon; Luscher, Walter G.; Mansurov, Jirgal; Roosendaal, Timothy J.; Borlaug, Brennan A.

    2013-08-06

    The use of SiC composites in fusion environments likely requires joining of plates using reactive joining or brazing. One promising reactive joining method uses solid-state displacement reactions between Si and TiC to produce Ti3SiC2 + SiC. We continue to explore the processing envelope for this joint for the TITAN collaboration in order to produce optimal joints to undergo irradiation studies in HFIR. One noted feature of the joints produced using tape-calendared powders of TiC+Si has been the large void regions that have been apparently unavoidable. Although the produced joints are very strong, these voids are undesirable. In addition, the tapes that were made for this joining were produced about 20 years ago and were aging. Therefore, we embarked on an effort to produce some new tape cast powders of TiC and Si that could replace our aging tape calendared materials.

  2. Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiN{sub x}/SiN{sub y} multilayers

    SciTech Connect (OSTI)

    Jiang, Xiaofan; Ma, Zhongyuan Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan

    2014-09-28

    Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiN{sub x}/SiN{sub y} multilayers with high on/off ratio of 10{sup 9}. High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.

  3. Chemical compatibility issues associated with use of SiC/SiC in advanced reactor concepts

    SciTech Connect (OSTI)

    Wilson, Dane F.

    2015-09-01

    Silicon carbide/silicon carbide (SiC/SiC) composites are of interest for components that will experience high radiation fields in the High Temperature Gas Cooled Reactor (HTGR), the Very High Temperature Reactor (VHTR), the Sodium Fast Reactor (SFR), or the Fluoride-cooled High-temperature Reactor (FHR). In all of the reactor systems considered, reactions of SiC/SiC composites with the constituents of the coolant determine suitability of materials of construction. The material of interest is nuclear grade SiC/SiC composites, which consist of a SiC matrix [high-purity, chemical vapor deposition (CVD) SiC or liquid phase-sintered SiC that is crystalline beta-phase SiC containing small amounts of alumina-yttria impurity], a pyrolytic carbon interphase, and somewhat impure yet crystalline beta-phase SiC fibers. The interphase and fiber components may or may not be exposed, at least initially, to the reactor coolant. The chemical compatibility of SiC/SiC composites in the three reactor environments is highly dependent on thermodynamic stability with the pure coolant, and on reactions with impurities present in the environment including any ingress of oxygen and moisture. In general, there is a dearth of information on the performance of SiC in these environments. While there is little to no excess Si present in the new SiC/SiC composites, the reaction of Si with O2 cannot be ignored, especially for the FHR, in which environment the product, SiO2, can be readily removed by the fluoride salt. In all systems, reaction of the carbon interphase layer with oxygen is possible especially under abnormal conditions such as loss of coolant (resulting in increased temperature), and air and/ or steam ingress. A global outline of an approach to resolving SiC/SiC chemical compatibility concerns with the environments of the three reactors is presented along with ideas to quickly determine the baseline compatibility performance of SiC/SiC.

  4. SiD Letter of Intent

    SciTech Connect (OSTI)

    Aihara, H.,; Burrows, P.,; Oreglia, M.,; Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; Zhang, Q.; Srivastava, A.; Butler, J.M.; Goldstein, Joel; Velthuis, J.; Radeka, V.; Zhu, R.-Y.; Lutz, P.; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; /CERN /Cornell U., LNS /Ewha Women's U., Seoul /Fermilab /Gent U. /Darmstadt, GSI /Imperial Coll., London /Barcelona, Inst. Microelectron. /KLTE-ATOMKI /Valencia U., IFIC /Cantabria Inst. of Phys. /Louis Pasteur U., Strasbourg I /Durham U., IPPP /Kansas State U. /Kyungpook Natl. U. /Annecy, LAPP /LLNL, Livermore /Louisiana Tech. U. /Paris U., VI-VII /Paris U., VI-VII /Munich, Max Planck Inst. /MIT, LNS /Chicago, CBC /Moscow State U. /Nanjing U. /Northern Illinois U. /Obninsk State Nucl. Eng. U. /Paris U., VI-VII /Strasbourg, IPHC /Prague, Inst. Phys. /Princeton U. /Purdue U. /Rutherford /SLAC /SUNY, Stony Brook /Barcelona U. /Bonn U. /UC, Davis /UC, Santa Cruz /Chicago U. /Colorado U. /Delhi U. /Hawaii U. /Helsinki U. /Indiana U. /Iowa U. /Massachusetts U., Amherst /Melbourne U. /Michigan U. /Minnesota U. /Mississippi U. /Montenegro U. /New Mexico U. /Notre Dame U. /Oregon U. /Oxford U. /Ramon Llull U., Barcelona /Rochester U. /Santiago de Compostela U., IGFAE /Hefei, CUST /Texas U., Arlington /Texas U., Dallas /Tokyo U. /Washington U., Seattle /Wisconsin U., Madison /Wayne State U. /Yale U. /Yonsei U.

    2012-04-11

    This document presents the current status of the Silicon Detector (SiD) effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R and D needed to provide the technical basis for an optimised SiD.

  5. HIGH-ENERGY NEUTRINO AND GAMMA-RAY TRANSIENTS FROM TRANS-RELATIVISTIC SUPERNOVA SHOCK BREAKOUTS

    SciTech Connect (OSTI)

    Kashiyama, Kazumi; Gao, Shan; Meszaros, Peter [Center for Particle and Gravitational Astrophysics, Department of Astronomy and Astrophysics, Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Murase, Kohta; Horiuchi, Shunsaku, E-mail: kzk15@psu.edu [CCAPP and Department of Physics, Ohio State University, 191 W. Woodruff Avenue, Columbus, OH 43210 (United States)

    2013-05-20

    Trans-relativistic shocks that accompany some supernovae (SNe) produce X-ray burst emissions as they break out in the dense circumstellar medium around the progenitors. This phenomenon is sometimes associated with peculiar low-luminosity gamma-ray bursts (LL GRBs). Here, we investigate the high-energy neutrino and gamma-ray counterparts of such a class of SNe. Just beyond the shock breakout radius, particle acceleration in the collisionless shock starts to operate in the presence of breakout photons. We show that protons may be accelerated to sufficiently high energies and produce high-energy neutrinos and gamma rays via the photomeson interaction. These neutrinos and gamma rays may be detectable from {approx}< 10 Mpc away by IceCube/KM3Net as multi-TeV transients almost simultaneously with the X-ray breakout, and even from {approx}< 100 Mpc away with follow-up observations by the Cherenkov Telescope Array using a wide-field sky monitor like Swift as a trigger. A statistical technique using a stacking approach could also be possible for the detection, with the aid of the SN optical/infrared counterparts. Such multi-messenger observations offer the possibility to probe the transition of trans-relativistic shocks from radiation-mediated to collisionless ones, and would also constrain the mechanisms of particle acceleration and emission in LL GRBs.

  6. Structure of Si-capped Ge/SiC/Si (001) epitaxial nanodots: Implications for quantum dot patterning

    SciTech Connect (OSTI)

    Petz, C. W.; Floro, J. A.; Yang, D.; Levy, J.

    2012-04-02

    Artificially ordered quantum dot (QD) arrays, where confined carriers can interact via direct exchange coupling, may create unique functionalities such as cluster qubits and spintronic bandgap systems. Development of such arrays for quantum computing requires fine control over QD size and spatial arrangement on the sub-35 nm length scale. We employ electron-beam irradiation to locally decompose ambient hydrocarbons onto a bare Si (001) surface. These carbonaceous patterns are annealed in ultra-high vacuum (UHV), forming ordered arrays of nanoscale SiC precipitates that have been suggested to template subsequent epitaxial Ge growth to form ordered QD arrays. We show that 3C-SiC nanodots form, in cube-on-cube epitaxial registry with the Si substrate. The SiC nanodots are fully relaxed by misfit dislocations and exhibit small lattice rotations with respect to the substrate. Ge overgrowth at elevated deposition temperatures, followed by Si capping, results in expulsion of the Ge from SiC template sites due to the large chemical and lattice mismatch between Ge and C. Maintaining an epitaxial, low-defectivity Si matrix around the quantum dots is important for creating reproducible electronic and spintronic coupling of states localized at the QDs.

  7. Monolayer-induced band shifts at Si(100) and Si(111) surfaces

    SciTech Connect (OSTI)

    Mkinen, A. J. Kim, Chul-Soo; Kushto, G. P.

    2014-01-27

    We report our study of the interfacial electronic structure of Si(100) and Si(111) surfaces that have been chemically modified with various organic monolayers, including octadecene and two para-substituted benzene derivatives. X-ray photoelectron spectroscopy reveals an upward band shift, associated with the assembly of these organic monolayers on the Si substrates, that does not correlate with either the dipole moment or the electron withdrawing/donating character of the molecular moieties. This suggests that the nature and quality of the self-assembled monolayer and the intrinsic electronic structure of the semiconductor material define the interfacial electronic structure of the functionalized Si(100) and Si(111) surfaces.

  8. The Dy-Ni-Si system as a representative of the rare earth-Ni-Si

    Office of Scientific and Technical Information (OSTI)

    family: Its isothermal section and new rare-earth nickel silicides (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: The Dy-Ni-Si system as a representative of the rare earth-Ni-Si family: Its isothermal section and new rare-earth nickel silicides Citation Details In-Document Search Title: The Dy-Ni-Si system as a representative of the rare earth-Ni-Si family: Its isothermal section and new rare-earth nickel silicides The Dy-Ni-Si system has been

  9. Synthesis of 4-substituted-trans-1, 2-diaminocyclohexyl polyaminocarboxylate metal chelating agents for the preparation of stable radiometal antibody immunoconjugates for therapy and spect and pet imaging

    DOE Patents [OSTI]

    Mease, Ronnie C. (Coram, NY); Mausner, Leonard F. (Stony Brook, NY); Srivastava, Suresh C. (Setauket, NY)

    1994-01-01

    Cyclo agents useful in forming antibody-metal conjugates useful for diagnostic and therapeutic purposes. New compounds and processes of forming these compounds are disclosed including 4-haloacetamido-trans-1,2-diaminocyclohexyl polyaminocarboxylate and 4-isothiocyanato-trans-1,2-diamino cyclohexane-N,N,N',N'-tetra acetic acid.

  10. Synthesis of 4-substituted-trans-1, 2-diaminocyclohexyl polyaminocarboxylate metal chelating agents for the preparation of stable radiometal antibody immunoconjugates for therapy and SPECT and PET imaging

    DOE Patents [OSTI]

    Mease, R.C.; Mausner, L.F.; Srivastava, S.C.

    1994-03-08

    Cyclo agents are described which are useful in forming antibody-metal conjugates which are used for diagnostic and therapeutic purposes. New compounds and processes of forming these compounds are disclosed including 4-haloacetamido-trans-1,2diaminocyclohexyl polyaminocarboxylate and 4-isothiocyanato-trans-1,2diamino cyclohexane-N,N,N',N'-tetra acetic acid. No Drawings

  11. POTENTIAL EVIDENCE FOR THE ONSET OF ALFVNIC TURBULENCE IN TRANS-EQUATORIAL CORONAL LOOPS

    SciTech Connect (OSTI)

    De Moortel, I.; Threlfall, J.; McIntosh, S. W.; Bethge, C.; Liu, J. E-mail: mscott@ucar.edu

    2014-02-20

    This study investigates Coronal Multi-channel Polarimeter Doppler-shift observations of a large, off-limb, trans-equatorial loop system observed on 2012 April 10-11. Doppler-shift oscillations with a broad range of frequencies are found to propagate along the loop with a speed of about 500kms{sup 1}. The power spectrum of perturbations travelling up from both loop footpoints is remarkably symmetric, probably due to the almost perfect north-south alignment of the loop system. Compared to the power spectrum at the footpoints of the loop, the Fourier power at the apex appears to be higher in the high-frequency part of the spectrum than expected from theoretical models. We suggest this excess high-frequency power could be tentative evidence for the onset of a cascade of the low-to-mid frequency waves into (Alfvnic) turbulence.

  12. SiXtron Advanced Materials | Open Energy Information

    Open Energy Info (EERE)

    Materials Jump to: navigation, search Name: SiXtron Advanced Materials Place: Quebec, Canada Website: www.sixtronadvancedmaterials.c References: SiXtron Advanced Materials1...

  13. Enhancement and Suppression of Photocurrent in Si Photodiodes...

    Office of Scientific and Technical Information (OSTI)

    Si Photodiodes by Nanoparticles and Nonlinear Terahertz Superconducting Metamaterials Citation Details In-Document Search Title: Enhancement and Suppression of Photocurrent in Si ...

  14. Synthesis and Characterization of Structured Si-Carbon Nanocomposite...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Characterization of Structured Si-Carbon Nanocomposite Anodes and Functional Polymer Binders Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes and ...

  15. HD Applications of Significantly Downsized SI Engines Using Alcohol...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Applications of Significantly Downsized SI Engines Using Alcohol DI for Knock Avoidance HD Applications of Significantly Downsized SI Engines Using Alcohol DI for Knock Avoidance ...

  16. Theoretical investigations of two Si-based spintronic materials...

    Office of Scientific and Technical Information (OSTI)

    Conference: Theoretical investigations of two Si-based spintronic materials Citation Details In-Document Search Title: Theoretical investigations of two Si-based spintronic ...

  17. Sustainable Investments Capital SI Capital | Open Energy Information

    Open Energy Info (EERE)

    Investments Capital SI Capital Jump to: navigation, search Name: Sustainable Investments Capital (SI Capital) Place: Barcelona, Spain Zip: 8021 Sector: Renewable Energy, Services...

  18. Solute embrittlement of SiC

    SciTech Connect (OSTI)

    Enrique, Ral A., E-mail: enriquer@umich.edu [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48103 (United States); Van der Ven, Anton, E-mail: avdv@engineering.ucsb.edu [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2014-09-21

    The energies and stresses associated with the decohesion of ?-SiC in the presence of mobile Pd and Ag impurities are studied from first principles. Density functional theory calculations are parameterized with a generalized cohesive zone model and are analyzed within a thermodynamic framework that accounts for realistic boundary conditions in the presence of mobile impurities. We find that Pd impurities will embrittle SiC when Pd is in equilibrium with metallic Pd precipitates. Our thermodynamic analysis predicts that Pd embrittles SiC by substantially reducing the maximum stress of decohesion as a result of a phase transition between decohering planes involving an influx of Pd atoms. The methods presented in this work can be applied to study the thermodynamics of decohesion of SiC in other aggressive environments containing oxygen and water, for example, and yield environment dependent cohesive zone models for use in continuum approaches to study crack propagation and fracture.

  19. High-performance Si microwire photovoltaics

    SciTech Connect (OSTI)

    Kelzenberg, Michael D.; Turner-Evans, Daniel B.; Putnam, Morgan C.; Boettcher, Shannon W.; Briggs, Ryan M.; Baek, Jae Y.; Lewis, Nathan S.; Atwater, Harry A.

    2011-01-07

    Crystalline Si wires, grown by the vaporliquidsolid (VLS) process, have emerged as promising candidate materials for low-cost, thin-film photovoltaics. Here, we demonstrate VLS-grown Si microwires that have suitable electrical properties for high-performance photovoltaic applications, including long minority-carrier diffusion lengths (Ln>> 30 m) and low surface recombination velocities (S << 70 cms-1). Single-wire radial pn junction solar cells were fabricated with amorphous silicon and silicon nitride surface coatings, achieving up to 9.0% apparent photovoltaic efficiency, and exhibiting up to ~600 mV open-circuit voltage with over 80% fill factor. Projective single-wire measurements and optoelectronic simulations suggest that large-area Si wire-array solar cells have the potential to exceed 17% energy-conversion efficiency, offering a promising route toward cost-effective crystalline Si photovoltaics.

  20. Si Pro AS | Open Energy Information

    Open Energy Info (EERE)

    Pro AS Jump to: navigation, search Name: Si Pro AS Place: Glomfjord, Norway Zip: 8161 Product: Silicon recycler with facility in Singapore. Coordinates: 66.807991, 13.97315...

  1. Transparent conductor-Si pillars heterojunction photodetector

    SciTech Connect (OSTI)

    Yun, Ju-Hyung; Kim, Joondong; Park, Yun Chang

    2014-08-14

    We report a high-performing heterojunction photodetector by enhanced surface effects. Periodically, patterned Si substrates were used to enlarge the photo-reactive regions and yield proportionally improved photo-responses. An optically transparent indium-tin-oxide (ITO) was deposited on a Si substrate and spontaneously formed an ITO/Si heterojunction. Due to an electrical conductive ITO film, ITO/Si heterojunction device can be operated at zero-bias, which effectively suppresses the dark current, resulting in better performances than those by a positive or a negative bias operation. This zero-bias operating heterojunction device exhibits a short response time (? 22.5?ms) due to the physical reaction to the incident light. We revealed that the location of the space charge region (SCR) is crucial for a specific photon-wavelength response. The SCR space has the highest collection efficiency of the photo-generated carriers. The photo-response can be maximized when we design the photodetector by superposing the SCR space over a corresponding photon-absorption length. The surface enhanced Si pillar devices significantly improved the photo-responses ratios from that of a planar Si device. According to this design scheme, a high photo-response ratio of 5560% was achieved at a wavelength of 600?nm. This surfaced-enhanced heterojunction design scheme would be a promising approach for various photoelectric applications.

  2. Roll Casting of Al-25%Si

    SciTech Connect (OSTI)

    Haga, Toshio [Osaka Institute of Technology, Omiya Asahiku Osaka city 535-8585 (Japan); Harada, Hideto [Graduate School of Osaka Institute of Technology, Omiya Asahiku Osaka city 535-8585 (Japan); Watari, Hisaki [Gunma University, Kiryu city, 376-8515 (Japan)

    2011-05-04

    Strip casting of Al-25%Si strip was tried using an unequal diameter twin roll caster. The diameter of the lower roll (large roll) was 1000 mm and the diameter of the upper roll (small roll) was 250 mm. Roll material was mild steel. The sound strip could be cast at the speeds ranging from 8 m/min to 12 m/min. The strip did not stick to the roll without the parting material. The primary Si, which existed at centre area of the thickness direction, was larger than that which existed at other area. The size of the primary Si was smaller than 0.2 mm. Eutectic Si was smaller 5 {mu}m. The as-cast strip was ranging from 2 mm to 3 mm thick and its width was 100 mm. The as-cast strip could be hot rolled down to 1 mm. The hot rolled strip was cold rolled. The primary Si became smaller and the pore occurred around the primary Si after the rolling.

  3. Characterization of SiGe/Si multi-quantum wells for infrared sensing

    SciTech Connect (OSTI)

    Moeen, M.; Salemi, A.; stling, M.; Radamson, H. H., E-mail: rad@kth.se [School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, 16640 Kista (Sweden); Kolahdouz, M. [School of Electrical and Computer Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)] [School of Electrical and Computer Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2013-12-16

    SiGe epitaxial layers are integrated as an active part in thermal detectors. To improve their performance, deeper understanding of design parameters, such as thickness, well periodicity, quality, and strain amount, of the layers/interfaces is required. Oxygen (22500??10{sup ?9}?Torr) was exposed prior or during epitaxy of SiGe/Si multilayers. In this range, samples with 10?nTorr oxygen were processed to investigate layer quality and noise measurements. Temperature coefficient of resistance was also measured to evaluate the thermal response. These results demonstrate sensitivity of SiGe-based devices to size and location of defects in the structure.

  4. ZnO/porous-Si and TiO{sub 2}/porous-Si nanocomposite nanopillars

    SciTech Connect (OSTI)

    Wang, Dong, E-mail: dong.wang@tu-ilmenau.de; Yan, Yong; Schaaf, Peter [Chair Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano, TU Ilmenau, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany); Sharp, Thomas [Oxford Instruments Plasma Technology Ltd., Yatton, Bristol BS49 4AP (United Kingdom); Schnherr, Sven; Ronning, Carsten [Institute for Solid State Physics, Friedrich Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Ji, Ran [SUSS MicroTec Lithography GmbH, Schleissheimer Str. 90, 85748 Garching (Germany)

    2015-01-01

    Porous Si nanopillar arrays are used as templates for atomic layer deposition of ZnO and TiO{sub 2}, and thus, ZnO/porous-Si and TiO{sub 2}/porous-Si nanocomposite nanopillars are fabricated. The diffusion of the precursor molecules into the inside of the porous structure occurs via Knudsen diffusion and is strongly limited by the small pore size. The luminescence of the ZnO/porous-Si nanocomposite nanopillars is also investigated, and the optical emission can be changed and even quenched after a strong plasma treatment. Such nanocomposite nanopillars are interesting for photocatalysis and sensors.

  5. Application of the Hartmann-Tran profile to precise experimental data sets of C?H?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Forthomme, D.; Cich, M. J.; Twagirayezu, S.; Hall, G. E.; Sears, T. J.

    2015-06-25

    Self- and nitrogen-broadened line shape data for the Pe(11) line of the ?? + ?? band of acetylene, recorded using a frequency comb-stabilized laser spectrometer, have been analyzed using the HartmannTran profile (HTP) line shape model in a multispectrum fitting. In total, the data included measurements recorded at temperatures between 125 K and 296 K and at pressures between 4 and 760 Torr. New, sub-Doppler, frequency comb-referenced measurements of the positions of multiple underlying hot band lines have also been made. These underlying lines significantly affect the Pe(11) line profile at temperatures above 240 K and poorly known frequencies previouslymoreintroduced errors into the line shape analyses. The behavior of the HTP model was compared to the quadratic speed dependent Voigt profile (QSDVP) expressed in the frequency and time domains. A parameter uncertainty analysis was carried out using a Monte Carlo method based on the estimated pressure, transmittance and frequency measurement errors. From the analyses, the Pe(11) line strength was estimated to be 1.2014(50) 10-20 in cm.molecules? units at 296 K with the standard deviation in parenthesis. For analyzing these data, we found that a reduced form of the HTP, equivalent to the QSDVP, was most appropriate because the additional parameters included in the full HTP were not well determined. As a supplement to this work, expressions for analytic derivatives and a lineshape fitting code written in Matlab for the HTP are available.less

  6. Small-Angle Neutron Scattering Studies of a-Si:H and a-Si:D

    SciTech Connect (OSTI)

    Williamson, D. L.; Marr, D. W. M.; Nelson, B. P.; Iwaniczko, E.; Yang, J.; Yan, B.; Guha, S.

    2000-01-01

    The heterogeneity of hydrogen and deuterium on the nanometer scale has been probed by samll-angle neutron scattering (SANS) from a-Si:H and a-Si:D films. Films were depsoited by two techniques, plasma-enhanced chemical vapor deposition (PECVD) and hot-wire chemical vapor deposition (HWCVD) using conditions that yield high quality films and devices.

  7. Synthesis of micro-sized interconnected Si-C composites

    DOE Patents [OSTI]

    Wang, Donghai; Yi, Ran; Dai, Fang

    2016-02-23

    Embodiments provide a method of producing micro-sized Si--C composites or doped Si--C and Si alloy-C with interconnected nanoscle Si and C building blocks through converting commercially available SiO.sub.x (0

  8. UNITED STATES ATOMIC ENERGY COMMISSION SAC200063~~0oooo Frank K. Pittman, Director, /Division of Waste Management and Trans-

    Office of Legacy Management (LM)

    SAC200063~~0oooo .- Frank K. Pittman, Director, /Division of Waste Management and Trans- portation, Headquarters CONTAMIWATRD EE-AEC-OWNED OR IEASED FACILITIES This memorandum responds to your TWX dated October 30, 1973, requesting certain information on the above subject. Unfortunately, some of the documentation necessary to answer your queries is no Longer available due to the records disposal program or the agreements pre- vailing at the time of release or transfer of the facilities. From

  9. Investigation of structural and electrical properties of flat a-Si/c-Si heterostructure fabricated by EBPVD technique

    SciTech Connect (OSTI)

    Demiro?lu, D.; Tatar, B.; Kazmanli, K.; Urgen, M.

    2013-12-16

    Flat amorphous silicon - crystal silicon (a-Si/c-Si) heterostructure were prepared by ultra-high vacuum electron beam evaporation technique on p-Si (111) and n-Si (100) single crystal substrates. Structural analyses were investigated by XRD, Raman and FEG-SEM analysis. With these analyses we determined that at the least amorphous structure shows modification but amorphous structure just protected. The electrical and photovoltaic properties of flat a-Si/c-Si heterojunction devices were investigated with current-voltage characteristics under dark and illumination conditions. Electrical properties of flat a-Si/c-Si heterorojunction; such as barrier height ?{sub B}, diode ideality factor ? were determined from current-voltage characteristics in dark conditions. These a-Si/c-Si heterostructure have good rectification behavior as a diode and exhibit high photovoltaic sensitivity.

  10. Application to Export Electric Energy OE Docket No. EA-216-C TransAlta Energy Marketing (U.S) Inc Sierra Club Withdrawal Motion

    Broader source: Energy.gov [DOE]

    Withdrawal of Sierra Club motion to intervene on the application to export electric energy OE Docket No. EA-216-C made by TransAlta Energy Marketing (U.S) Inc.

  11. Direct growth of graphene on Si(111)

    SciTech Connect (OSTI)

    Thanh Trung, Pham Joucken, Frdric; Colomer, Jean-Franois; Robert, Sporken; Campos-Delgado, Jessica; Raskin, Jean-Pierre; Hackens, Benot; Santos, Cristiane N.

    2014-06-14

    Due to the need of integrated circuit in the current silicon technology, the formation of graphene on Si wafer is highly desirable, but is still a challenge for the scientific community. In this context, we report the direct growth of graphene on Si(111) wafer under appropriate conditions using an electron beam evaporator. The structural quality of the material is investigated in detail by reflection high energy electron diffraction, Auger electron spectroscopy, X-ray photoemission spectroscopy, Raman spectroscopy, high resolution scanning electron microscopy, atomic force microscopy, and scanning tunneling microscopy. Our experimental results confirm that the quality of graphene is strongly dependent on the growth time during carbon atoms deposition.

  12. Ag on Si(111) from basic science to application

    SciTech Connect (OSTI)

    Belianinov, Aleksey

    2012-04-04

    In our work we revisit Ag and Au adsorbates on Si(111)-7x7, as well as experiment with a ternary system of Pentacene, Ag and Si(111). Of particular interest to us is the Si(111)-({radical}3x{radical}3)R30{degree}Ag (Ag-Si-{radical}3 hereafter). In this thesis I systematically e plore effects of Ag deposition on the Ag-Si-{radical}3 at different temperatures, film thicknesses and deposition fluxes. The generated insight of the Ag system on the Si(111) is then applied to generate novel methods of nanostructuring and nanowire growth. I then extend our expertise to the Au system on the Ag-Si(111) to gain insight into Au-Si eutectic silicide formation. Finally we explore behavior and growth modes of an organic molecule on the Ag-Si interface.

  13. Operational Challenges in Gas-To-Liquid (GTL) Transportation Through Trans Alaska Pipeline System (TAPS)

    SciTech Connect (OSTI)

    Godwin A. Chukwu; Santanu Khataniar; Shirish Patil; Abhijit Dandekar

    2006-06-30

    Oil production from Alaskan North Slope oil fields has steadily declined. In the near future, ANS crude oil production will decline to such a level (200,000 to 400,000 bbl/day) that maintaining economic operation of the Trans-Alaska Pipeline System (TAPS) will require pumping alternative products through the system. Heavy oil deposits in the West Sak and Ugnu formations are a potential resource, although transporting these products involves addressing important sedimentation issues. One possibility is the use of Gas-to-Liquid (GTL) technology. Estimated recoverable gas reserves of 38 trillion cubic feet (TCF) on the North Slope of Alaska can be converted to liquid with GTL technology and combined with the heavy oils for a product suitable for pipeline transport. Issues that could affect transport of this such products through TAPS include pumpability of GTL and crude oil blends, cold restart of the pipeline following a prolonged winter shutdown, and solids deposition inside the pipeline. This study examined several key fluid properties of GTL, crude oil and four selected blends under TAPS operating conditions. Key measurements included Reid Vapor Pressure, density and viscosity, PVT properties, and solids deposition. Results showed that gel strength is not a significant factor for the ratios of GTL-crude oil blend mixtures (1:1; 1:2; 1:3; 1:4) tested under TAPS cold re-start conditions at temperatures above - 20 F, although Bingham fluid flow characteristics exhibited by the blends at low temperatures indicate high pumping power requirements following prolonged shutdown. Solids deposition is a major concern for all studied blends. For the commingled flow profile studied, decreased throughput can result in increased and more rapid solid deposition along the pipe wall, resulting in more frequent pigging of the pipeline or, if left unchecked, pipeline corrosion.

  14. Comparison of the vacuum-ultraviolet radiation response of HfO{sub 2}/SiO{sub 2}/Si dielectric stacks with SiO{sub 2}/Si

    SciTech Connect (OSTI)

    Upadhyaya, G. S.; Shohet, J. L.

    2007-02-12

    Vacuum ultraviolet (vuv) emitted during plasma processing degrades dielectrics by generating electron-hole pairs. VUV-induced charging of SiO{sub 2}/p-Si and HfO{sub 2}/SiO{sub 2}/p-Si dielectric stacks are compared. For SiO{sub 2}/p-Si, charging is observed for photon energies >15 eV by ionization of dielectric atoms from photoinjected electrons. In HfO{sub 2}/SiO{sub 2}/p-Si, charging is observed for photon >10 eV and is due to ionization by photoinjected electrons and by H{sup +} trapping in the HfO{sub 2}/SiO{sub 2} bulk. Hydrogen appears during annealing at the Si-SiO{sub 2} interface forming Si-H, which, during irradiation, is depassivated by photoinjected electrons. The authors conclude that dielectric charging in thin oxides (<10 nm) occurs more easily in HfO{sub 2}/SiO{sub 2} than in SiO{sub 2}.

  15. Theoretical investigations of two Si-based spintronic materials

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Conference: Theoretical investigations of two Si-based spintronic materials Citation Details In-Document Search Title: Theoretical investigations of two Si-based spintronic materials Two Si-based spintronic materials, a Mn-Si digital ferromagnetic heterostructure ({delta}-layer of Mn doped in Si) with defects and dilutely doped Mn{sub x}Si{sub 1-x} alloy are investigated using a density-functional based approach. We model the heterostructure and alloy with a

  16. Current Status and Recent Research Achievements in SiC/SiC Composites

    SciTech Connect (OSTI)

    Katoh, Yutai; Snead, Lance L.; Henager, Charles H.; Nozawa, T.; Hinoki, Tetsuya; Ivekovic, Aljaz; Novak, Sasa; Gonzalez de Vicente, Sehila M.

    2014-12-01

    The development and maturation of the silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC) composite system for fusion applications has seen the evolution from fundamental development and understanding of the material system and its behavior in a hostile irradiation environment to the current effort which essentially is a broad-based program of technology, directed at moving this material class from a laboratory curiosity to an engineering material. This paper lays out the recent international scientific and technological achievements in the development of SiC/SiC composite material technologies for fusion application and will discuss future research directions. It also reviews the materials system in the larger context of progress to maturity as an engineering material for both the larger nuclear community and for general engineering applications.

  17. Ni-Si Alloys for the S-I Reactor-Hydrogen Production Process Interface

    SciTech Connect (OSTI)

    Joseph W. Newkirk; Richard K. Brow

    2010-01-21

    The overall goal of this project was to develop Ni-Si alloys for use in vessels to contain hot, pressurized sulfuric acid. The application was to be in the decomposition loop of the thermochemical cycle for production of hydrogen.

  18. SiN-SiC nanofilm: A nano-functional ceramic with bipolar magnetic semiconducting character

    SciTech Connect (OSTI)

    Zhang, Jiahui; Li, Xingxing; Yang, Jinlong

    2014-04-28

    Nowadays, functional ceramics have been largely explored for application in various fields. However, magnetic functional ceramics for spintronics remain little studied. Here, we propose a nano-functional ceramic of sphalerite SiN-SiC nanofilm with intrinsic ferromagnetic order. Based on first principles calculations, the SiN-SiC nanofilm is found to be a ferromagnetic semiconductor with an indirect band gap of 1.71 eV. By mean field theory, the Curie temperature is estimated to be 304 K, close to room temperature. Furthermore, the valence band and conduction band states of the nanofilm exhibit inverse spin-polarization around the Fermi level. Thus, the SiN-SiC nanofilm is a typical bipolar magnetic semiconductor in which completely spin-polarized currents with reversible spin polarization can be created and controlled by applying a gate voltage. Such a nano-functional ceramic provides a possible route for electrical manipulation of carrier's spin orientation.

  19. SiC Processing AG | Open Energy Information

    Open Energy Info (EERE)

    SiC Processing AG Jump to: navigation, search Name: SiC Processing AG Place: Hirschau, Germany Zip: 92242 Sector: Solar Product: Offers management and recycling of slurry for solar...

  20. Silicon Genesis Corp SiGen | Open Energy Information

    Open Energy Info (EERE)

    Corp SiGen Jump to: navigation, search Name: Silicon Genesis Corp (SiGen) Place: San Jose, California Zip: 95134 Product: US-based manufacturer of proton-shooting wafer slicing...

  1. SiG Solar GmbH | Open Energy Information

    Open Energy Info (EERE)

    SiG Solar GmbH Jump to: navigation, search Name: SiG Solar GmbH Place: Stuhr-Brinkum, Germany Zip: 28816 Sector: Solar Product: Supplier of mounting systems, and trade name in...

  2. FRV SI Transport Solar LP | Open Energy Information

    Open Energy Info (EERE)

    SI Transport Solar LP Jump to: navigation, search Name: FRV SI Transport Solar LP Place: Arizona References: EIA Form EIA-861 Final Data File for 2010 - File220101 EIA Form 861...

  3. Special Inquiry: SI-11-27 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Inquiry: SI-11-27 Special Inquiry: SI-11-27 November 27, 2006 Selected Controls over Classified Information at the Los Alamos National Laboratory PDF icon Special Inquiry: SI-11-27 More Documents & Publications Special Inquiry: OAS-SR-07-01 Special Inquiry: IG-0584 Inspection Report: IG-0656

  4. Characterization of SiO{sub 2}/SiN{sub x} gate insulators for graphene based nanoelectromechanical systems

    SciTech Connect (OSTI)

    Tvri, E.; Csontos, M., E-mail: csontos@dept.phy.bme.hu; Krivchy, T.; Csonka, S. [Department of Physics, Budapest University of Technology and Economics and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki t 8, H-1111 Budapest (Hungary); Frjes, P. [MEMS Lab, Institute for Technical Physics and Materials Science, RCNS, HAS, Konkoly-Thege t 29-33, H-1121 Budapest (Hungary)

    2014-09-22

    The structural and magnetotransport characterization of graphene nanodevices exfoliated onto Si/SiO{sub 2}/SiN{sub x} heterostructures are presented. Improved visibility of the deposited flakes is achieved by optimal tuning of the dielectric film thicknesses. The conductance of single layer graphene Hall-bar nanostructures utilizing SiO{sub 2}/SiN{sub x} gate dielectrics were characterized in the quantum Hall regime. Our results highlight that, while exhibiting better mechanical and chemical stability, the effect of non-stoichiometric SiN{sub x} on the charge carrier mobility of graphene is comparable to that of SiO{sub 2}, demonstrating the merits of SiN{sub x} as an ideal material platform for graphene based nanoelectromechanical applications.

  5. Si-based RF MEMS components.

    SciTech Connect (OSTI)

    Stevens, James E.; Nordquist, Christopher Daniel; Baker, Michael Sean; Fleming, James Grant; Stewart, Harold D.; Dyck, Christopher William

    2005-01-01

    Radio frequency microelectromechanical systems (RF MEMS) are an enabling technology for next-generation communications and radar systems in both military and commercial sectors. RF MEMS-based reconfigurable circuits outperform solid-state circuits in terms of insertion loss, linearity, and static power consumption and are advantageous in applications where high signal power and nanosecond switching speeds are not required. We have demonstrated a number of RF MEMS switches on high-resistivity silicon (high-R Si) that were fabricated by leveraging the volume manufacturing processes available in the Microelectronics Development Laboratory (MDL), a Class-1, radiation-hardened CMOS manufacturing facility. We describe novel tungsten and aluminum-based processes, and present results of switches developed in each of these processes. Series and shunt ohmic switches and shunt capacitive switches were successfully demonstrated. The implications of fabricating on high-R Si and suggested future directions for developing low-loss RF MEMS-based circuits are also discussed.

  6. Method for enhancing growth of SiO.sub.2 in Si by the implantation of germanium

    DOE Patents [OSTI]

    Holland, Orin W.; Fathy, Dariush; White, Clark W.

    1990-04-24

    A method for enhancing the conversion of Si to SiO.sub.2 in a directional fashion wherein steam or wet oxidation of Si is enhanced by the prior implantation of Ge into the Si. The unique advantages of the Ge impurity include the directional enhancement of oxidation and the reduction in thermal budget, while at the same time, Ge is an electrically inactive impurity.

  7. Thermodynamic and kinetic control of the lateral Si wire growth

    SciTech Connect (OSTI)

    Dedyulin, Sergey N. Goncharova, Lyudmila V.

    2014-03-24

    Reproducible lateral Si wire growth has been realized on the Si (100) surface. In this paper, we present experimental evidence showing the unique role that carbon plays in initiating lateral growth of Si wires on a Si (100) substrate. Once initiated in the presence of ?5 ML of C, lateral growth can be achieved in the range of temperatures, T?=?450650?C, and further controlled by the interplay of the flux of incoming Si atoms with the size and areal density of Au droplets. Critical thermodynamic and kinetic aspects of the growth are discussed in detail.

  8. Interfacing the Ab initio multiple spawning method with electronic structure methods in GAMESS: Photodecay of trans-Azomethane

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gaenko, Alexander; DeFusco, Albert; Varganov, Sergey A.; Martínez, Todd J.; Gordon, Mark S.

    2014-10-20

    This work presents a nonadiabatic molecular dynamics study of the nonradiative decay of photoexcited trans-azomethane, using the ab initio multiple spawning (AIMS) program that has been interfaced with the General Atomic and Molecular Electronic Structure System (GAMESS) quantum chemistry package for on-the-fly electronic structure evaluation. The interface strategy is discussed, and the capabilities of the combined programs are demonstrated with a nonadiabatic molecular dynamics study of the nonradiative decay of photoexcited trans-azomethane. Energies, gradients, and nonadiabatic coupling matrix elements were obtained with the state-averaged complete active space self-consistent field method, as implemented in GAMESS. The influence of initial vibrational excitationmore » on the outcome of the photoinduced isomerization is explored. Increased vibrational excitation in the CNNC torsional mode shortens the excited state lifetime. Depending on the degree of vibrational excitation, the excited state lifetime varies from ~60–200 fs. As a result, these short lifetimes are in agreement with time-resolved photoionization mass spectroscopy experiments.« less

  9. Strain and stability of ultrathin Ge layers in Si/Ge/Si axial heterojunction nanowires

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ross, Frances M.; Stach, Eric A.; Wen, Cheng -Yen; Reuter, Mark C.; Su, Dong

    2015-02-05

    The abrupt heterointerfaces in the Si/Ge materials system presents useful possibilities for electronic device engineering because the band structure can be affected by strain induced by the lattice mismatch. In planar layers, heterointerfaces with abrupt composition changes are difficult to realize without introducing misfit dislocations. However, in catalytically grown nanowires, abrupt heterointerfaces can be fabricated by appropriate choice of the catalyst. Here we grow nanowires containing Si/Ge and Si/Ge/Si structures respectively with sub-1nm thick Ge "quantum wells" and we measure the interfacial strain fields using geometric phase analysis. Narrow Ge layers show radial strains of several percent, with a correspondingmore » dilation in the axial direction. Si/Ge interfaces show lattice rotation and curvature of the lattice planes. We conclude that high strains can be achieved, compared to what is possible in planar layers. In addition, we study the stability of these heterostructures under heating and electron beam irradiation. The strain and composition gradients are supposed to the cause of the instability for interdiffusion.« less

  10. Light emission from Si nanoclusters formed at low temperatures

    SciTech Connect (OSTI)

    Pi, X.D.; Zalloum, O.H.Y.; Roschuk, T.; Wojcik, J.; Knights, A.P.; Mascher, P.; Simpson, P.J.

    2006-03-06

    Photoluminescence (PL) from amorphous Si nanoclusters (Si-ncls) formed by thin-film deposition via electron-cyclotron resonance plasma-enhanced chemical vapor deposition followed by annealing at temperatures {<=}875 deg. C has been investigated. We find that Si-ncls grow very slowly after their initial nucleation at low temperatures. An increase in the size of Si-ncls, which can be controlled by the annealing temperature, induces a redshift in the Si-ncl PL peak. While the emitted optical power is more than 100 times smaller than that of Si nanocrystals formed in an identically deposited film, it is increased by a factor of up to approximately four times following hydrogen passivation. The incorporation of hydrogen causes a redshift in the PL peak position, suggesting a partial hydrogenation induced bond distortion of the Si-ncls. This redshift decreases with increasing hydrogen ambient annealing temperature.

  11. Prediction of Thermal Conductivity for Irradiated SiC/SiC Composites by Informing Continuum Models with Molecular Dynamics Data

    SciTech Connect (OSTI)

    Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.

    2014-05-01

    This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal ?-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.

  12. Evaluate Si Layers: Cooperative Research and Development Final Report, CRADA Number CRD-07-255

    SciTech Connect (OSTI)

    Teplin, C.

    2013-04-01

    Evaluate Si layers based on heteroepitaxial Si growth on RABITS textured metal substrates coated with textured buffer layers.

  13. Tin induced a-Si crystallization in thin films of Si-Sn alloys

    SciTech Connect (OSTI)

    Neimash, V. E-mail: oleks.goushcha@nuportsoft.com; Poroshin, V.; Goushcha, A. O. E-mail: oleks.goushcha@nuportsoft.com; Shepeliavyi, P.; Yukhymchuk, V.; Melnyk, V.; Kuzmich, A.; Makara, V.

    2013-12-07

    Effects of tin doping on crystallization of amorphous silicon were studied using Raman scattering, Auger spectroscopy, scanning electron microscopy, and X-ray fluorescence techniques. Formation of silicon nanocrystals (24?nm in size) in the amorphous matrix of Si{sub 1?x}Sn{sub x}, obtained by physical vapor deposition of the components in vacuum, was observed at temperatures around 300?C. The aggregate volume of nanocrystals in the deposited film of Si{sub 1?x}Sn{sub x} exceeded 60% of the total film volume and correlated well with the tin content. Formation of structures with ?80% partial volume of the nanocrystalline phase was also demonstrated. Tin-induced crystallization of amorphous silicon occurred only around the clusters of metallic tin, which suggested the crystallization mechanism involving an interfacial molten Si:Sn layer.

  14. Si/SiGe electron resonant tunneling diodes with graded spacer wells

    SciTech Connect (OSTI)

    Paul, D. J.; See, P.; Bates, R.; Griffin, N.; Coonan, B. P.; Redmond, G.; Crean, G. M.; Zozoulenko, I. V.; Berggren, K.-F.; Hollander, B.

    2001-06-25

    Resonant tunneling diodes have been fabricated using graded Si{sub 1{minus}x}Ge{sub x} (x=0.3{r_arrow}0.0) spacer wells and strained Si{sub 0.4}Ge{sub 0.6} barriers on a relaxed Si{sub 0.7}Ge{sub 0.3} n-type substrate which demonstrates negative differential resistance at up to 100 K. This design is aimed at reducing the voltage at which the peak current density is achieved. Peak current densities of 0.08A/cm{sup 2} with peak-to-valley current ratios of 1.67 have been achieved for a low peak voltage of 40 mV at 77 K. This represents an improvement of over an order of magnitude compared to previous work. {copyright} 2001 American Institute of Physics.

  15. Scattering mechanisms in shallow undoped Si/SiGe quantum wells

    SciTech Connect (OSTI)

    Laroche, Dominique; Huang, S. -H.; Nielsen, Erik; Chuang, Y.; Li, J. -Y.; Liu, C. W.; Lu, Tzu -Ming

    2015-10-07

    We report the magneto-transport study and scattering mechanism analysis of a series of increasingly shallow Si/SiGe quantum wells with depth ranging from ~ 100 nm to ~ 10 nm away from the heterostructure surface. The peak mobility increases with depth, suggesting that charge centers near the oxide/semiconductor interface are the dominant scattering source. The power-law exponent of the electron mobility versus density curve, ? ? n?, is extracted as a function of the depth of the Si quantum well. At intermediate densities, the power-law dependence is characterized by ? ~ 2.3. At the highest achievable densities in the quantum wells buried at intermediate depth, an exponent ? ~ 5 is observed. Lastly, we propose and show by simulations that this increase in the mobility dependence on the density can be explained by a non-equilibrium model where trapped electrons smooth out the potential landscape seen by the two-dimensional electron gas.

  16. Thermal conductivity in nanocrystalline-SiC/C superlattices

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Habermehl, S.; Serrano, J. R.

    2015-11-17

    We reported the formation of thin film superlattices consisting of alternating layers of nitrogen-doped SiC (SiC:N) and C. Periodically terminating the SiC:N surface with a graphitic C boundary layer and controlling the SiC:N/C thickness ratio yield nanocrystalline SiC grains ranging in size from 365 to 23 nm. Frequency domain thermo-reflectance is employed to determine the thermal conductivity, which is found to vary from 35.5 W m-1 K-1 for monolithic undoped α-SiC films to 1.6 W m-1 K-1 for a SiC:N/C superlattice with a 47 nm period and a SiC:N/C thickness ratio of 11. A series conductance model is employed tomore » explain the dependence of the thermal conductivity on the superlatticestructure. Our results indicate that the thermal conductivity is more dependent on the SiC:N/C thickness ratio than the SiC:N grain size, indicative of strong boundary layerphonon scattering.« less

  17. Synthesis, electronic and optical properties of Si nanostructures

    SciTech Connect (OSTI)

    Dinh, L.N.

    1996-09-01

    Silicon and silicon oxide nanostructures have been deposited on solid substrates, in an ultra high vacuum (UHV) chamber, by laser ablation or thermal vaporization. Laser ablation followed by substrate post annealing produced Si clusters with average size of a few nanometers, on highly oriented pyrolytic graphite (HOPG) surfaces. This technique, which is based on surface diffusion, is limited to the production of less than one layer of clusters on a given surface. The low coverage of Si clusters and the possibility of nonradiative decay of excitation in the Si cores to the HOPG substrates in these samples rendered them unsuitable for many optical measurements. Thermal vaporization of Si in an Ar buffer gas, on the contrary, yielded multilayer coverage of Si nanoclusters with a fairly narrow size distribution of about 2 nm, full width at half maximum (FWHM). As a result, further study was performed only on Si nanoclusters synthesized by thermal vaporization in a buffer gas. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) revealed that these nanoclusters were crystalline. However, during synthesis, if oxygen was the buffer gas, a network of amorphous Si oxide nanostructures (an-SiO{sub x}) with occasional embedded Si dots was formed. All samples showed strong infrared and/or visible photoluminescence (PL) with varying decay times from nanoseconds to microseconds depending on synthesis conditions. There were differences in PL spectra for hydrogen and oxygen passivated nc-Si, while many common PL properties between oxygen passivated nc-Si and an SiO{sub x} were observed. The observed experimental results can be best explained by a model involving absorption between quantum confined states in the Si cores and emission for which the decay times are very sensitive to surface and/or interface states.

  18. Phonon-assisted transient electroluminescence in Si

    SciTech Connect (OSTI)

    Cheng, Tzu-Huan, E-mail: f94943139@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan (China); Chu-Su, Yu [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan and Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan (China); Liu, Chien-Sheng [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, Chii-Wann [Institute of Biomedical Engineering and Institute of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China)

    2014-06-30

    The phonon-replica infrared emission is observed at room temperature from indirect band gap Si light-emitting diode under forward bias. With increasing injection current density, the broadened electroluminescence spectrum and band gap reduction are observed due to joule heating. The spectral-resolved temporal response of electroluminescence reveals the competitiveness between single (TO) and dual (TO?+?TA) phonon-assisted indirect band gap transitions. As compared to infrared emission with TO phonon-replica, the retarder of radiative recombination at long wavelength region (?1.2??m) indicates lower transition probability of dual phonon-replica before thermal equivalent.

  19. OTY NO S:i

    Office of Scientific and Technical Information (OSTI)

    OTY NO S:i Sí A major purpose of the Techni- cal Information Center is to provide the broadest dissemination possi- ble of information contained in DOE's Research and Development Reports to business, industry, the academic community, and federal, state and local governments. Although a small portion of this report is not reproducible, it is being made available to expedite the availability of information on the research discussed herein. ORNL/FBDC-83/9 DE85 010208 ORNL Fusion Program ^ MFTF-a+T

  20. T O FRI SI' NAI CI'

    Office of Legacy Management (LM)

    O FRI SI' NAI CI' aqr! I I TYI --, B CA.7 MEHORCiNDUM fr -!!h&-$-G-y------- _____ -i=Tf-:-%!-.s *ner contacted 0 yes ji&yc; ,"~--c&.--~.--~~~ = OF OPERATION =------------- m---4 iesearch & Devrlopment R Facility Type ! Production scale testing 0 Manufacturing Pilot Scale [ Bench Scale Process t--J Univereity 3 Theoretical Studies x Research Organization fl Qovernment Sponeored F a c i l i t y Sample & Analysis 0 Other --------------------- ??$?oduction 0 Diapoeal

  1. Direct growth of few-layer graphene on 6H-SiC and 3C-SiC/Si via propane chemical vapor deposition

    SciTech Connect (OSTI)

    Michon, A.; Vezian, S.; Portail, M.; Ouerghi, A.; Zielinski, M.; Chassagne, T.

    2010-10-25

    We propose to grow graphene on SiC by a direct carbon feeding through propane flow in a chemical vapor deposition reactor. X-ray photoemission and low energy electron diffraction show that propane allows to grow few-layer graphene (FLG) on 6H-SiC(0001). Surprisingly, FLG grown on (0001) face presents a rotational disorder similar to that observed for FLG obtained by annealing on (000-1) face. Thanks to a reduced growth temperature with respect to the classical SiC annealing method, we have also grown FLG/3C-SiC/Si(111) in a single growth sequence. This opens the way for large-scale production of graphene-based devices on silicon substrate.

  2. Synthesis of 4-substituted-trans-1,2-diaminocyclohexyl polyaminocarboxylate metal chelating agents for the preparation of stable radiometal antibody immunoconjugates for therapy and spect and pet imaging

    DOE Patents [OSTI]

    Mease, Ronnie C.; Kolsky, Kathryn L.; Mausner, Leonard F.; Srivastava, Suresh C.

    1997-06-03

    Cyclohexyl chelating agents useful in forming antibody-metal conjugates useful for diagnostic and therapeutic purposes. New compounds and processes of forming these compounds are disclosed including 4-haloacetamido-trans-1,2-diaminocyclohexyl polyaminocarboxylate and 4-isothiocyanato-trans-1,2-diamino cyclohexane-N, N, N', N'-tetra acetic acid.

  3. Synthesis of 4-substituted-trans-1,2-diaminocyclohexyl polyaminocarboxylate metal chelating agents for the preparation of stable radiometal antibody immunoconjugates for therapy and SPECT and PET imaging

    DOE Patents [OSTI]

    Mease, R.C.; Kolsky, K.L.; Mausner, L.F.; Srivastava, S.C.

    1997-06-03

    Cyclohexyl chelating agents useful in forming antibody-metal conjugates which are used for diagnostic and therapeutic purposes are synthesized. New compounds and processes of forming these compounds are disclosed including 4-haloacetamido-trans-1,2-diaminocyclohexyl polyaminocarboxylate and 4-isothiocyanato-trans-1,2-diamino cyclohexane-N,N,N{prime},N{prime}-tetra acetic acid.

  4. First-principles study of the Pd–Si system and Pd(001)/SiC(001) hetero-structure

    SciTech Connect (OSTI)

    Turchi, P.E.A.; Ivashchenko, V.I.

    2014-11-01

    First-principles molecular dynamics simulations of the Pd(001)/3C–SiC(001) nano-layered structure were carried out at different temperatures ranging from 300 to 2100 K. Various PdSi (Pnma, Fm3m, P6m2, Pm3m), Pd2Si (P6⁻2m, P63/mmc, P3m1, P3⁻1m) and Pd3Si (Pnma, P6322, Pm3m, I4/mmm) structures under pressure were studied to identify the structure of the Pd/Si and Pd/C interfaces in the Pd/SiC systems at high temperatures. It was found that a large atomic mixing at the Pd/Si interface occurred at 1500–1800 K, whereas the Pd/C interface remained sharp even at the highest temperature of 2100 K. At the Pd/C interface, voids and a graphite-like clustering were detected. Palladium and silicon atoms interact at the Pd/Si interface to mostly form C22-Pd2Si and D011-Pd3Si fragments, in agreement with experiment.

  5. Ultra-high current density thin-film Si diode

    DOE Patents [OSTI]

    Wang, Qi

    2008-04-22

    A combination of a thin-film .mu.c-Si and a-Si:H containing diode structure characterized by an ultra-high current density that exceeds 1000 A/cm.sup.2, comprising: a substrate; a bottom metal layer disposed on the substrate; an n-layer of .mu.c-Si deposited the bottom metal layer; an i-layer of .mu.c-Si deposited on the n-layer; a buffer layer of a-Si:H deposited on the i-layer, a p-layer of .mu.c-Si deposited on the buffer layer; and a top metal layer deposited on the p-layer.

  6. Epitaxial CoSi2 on MOS devices

    DOE Patents [OSTI]

    Lim, Chong Wee (Urbana, IL); Shin, Chan Soo (Daejeon, KR); Petrov, Ivan Georgiev (Champaign, IL); Greene, Joseph E. (Champaign, IL)

    2005-01-25

    An Si.sub.x N.sub.y or SiO.sub.x N.sub.y liner is formed on a MOS device. Cobalt is then deposited and reacts to form an epitaxial CoSi.sub.2 layer underneath the liner. The CoSi.sub.2 layer may be formed through a solid phase epitaxy or reactive deposition epitaxy salicide process. In addition to high quality epitaxial CoSi.sub.2 layers, the liner formed during the invention can protect device portions during etching processes used to form device contacts. The liner can act as an etch stop layer to prevent excessive removal of the shallow trench isolation, and protect against excessive loss of the CoSi.sub.2 layer.

  7. West Texas geothermal resource assessment. Part II. Preliminary utilization assessment of the Trans-Pecos geothermal resource. Final report

    SciTech Connect (OSTI)

    Gilliland, M.W.; Fenner, L.B.

    1980-01-01

    The utilization potential of geothermal resources in Trans-Pecos, Texas was assessed. The potential for both direct use and electric power generation were examined. As with the resource assessment work, the focus was on the Hueco Tanks area in northeastern El Paso County and the Presidio Bolson area in Presidio County. Suitable users of the Hueco Tanks and Presidio Bolson resource areas were identified by matching postulated temperature characteristics of the geothermal resource to the need characteristics of existing users in each resource area. The amount of geothermal energy required and the amount of fossil fuel that geothermal energy would replace were calculated for each of the users identified as suitable. Current data indicate that temperatures in the Hueco Tanks resource area are not high enough for electric power generation, but in at least part of the Presidio Bolson resource area, they may be high enough for electric power generation.

  8. Steel-SiC Metal Matrix Composite Development

    SciTech Connect (OSTI)

    Smith, Don D.

    2005-07-17

    The goal of this project is to develop a method for fabricating SiC-reinforced high-strength steel. We are developing a metal-matrix composite (MMC) in which SiC fibers are be embedded within a metal matrix of steel, with adequate interfacial bonding to deliver the full benefit of the tensile strength of the SiC fibers in the composite.

  9. Intrinsic carrier multiplication efficiency in bulk Si crystals evaluated

    Office of Scientific and Technical Information (OSTI)

    by optical-pump/terahertz-probe spectroscopy (Journal Article) | SciTech Connect Intrinsic carrier multiplication efficiency in bulk Si crystals evaluated by optical-pump/terahertz-probe spectroscopy Citation Details In-Document Search Title: Intrinsic carrier multiplication efficiency in bulk Si crystals evaluated by optical-pump/terahertz-probe spectroscopy We estimated the carrier multiplication efficiency in the most common solar-cell material, Si, by using optical-pump/terahertz-probe

  10. Hail Impact Testing on Crystalline Si Modules with Flexible Packaging |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Hail Impact Testing on Crystalline Si Modules with Flexible Packaging Hail Impact Testing on Crystalline Si Modules with Flexible Packaging Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PDF icon pvmrw13_ps2_westpak_brown.pdf More Documents & Publications Test Procedure for UV Weathering Resistance of Backsheet The Acceleration of Degradation by HAST and Air-HAST in c-Si PV Modules Improved Reliability of PV Modules with

  11. Centrotherm SiTec GmbH | Open Energy Information

    Open Energy Info (EERE)

    Germany Product: Germany-based subsidiary of Centrotherm. The unit provides turnkey manufacturing equipment for polysilicon factory. References: Centrotherm SiTec GmbH1 This...

  12. Synthesis and Characterization of Structured Si-Carbon Nanocomposite...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Novel Lithium Ion Anode Structures: Overview of New DOE BATT Anode Projects Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes and Functional Polymer ...

  13. Method for the hydrogenation of poly-si

    DOE Patents [OSTI]

    Wang, Qi

    2013-11-12

    A method for hydrogenating poly-si. Poly-si is placed into the interior of a chamber. A filament is placed into the interior of a chamber. The base pressure of the interior of the chamber is evacuated, preferably to 10.sup.-6 Torr or less. The poly-si is heated for a predetermined poly-si heating time. The filament is heated by providing an electrical power to the filament. Hydrogen is supplied into the pressurized interior of the chamber comprising the heated poly-si and the heated filament. Atomic hydrogen is produced by the filament at a rate whereby the atomic hydrogen surface density at the poly-si is less than the poly-si surface density. Preferably, the poly-si is covered from the atomic hydrogen produced by the heated filament for a first predetermined covering time. Preferably, the poly-si is then uncovered from the atomic hydrogen produced by the heated filament for a first hydrogenation time.

  14. Buckeye Silicon BeSi | Open Energy Information

    Open Energy Info (EERE)

    Name: Buckeye Silicon (BeSi) Place: Toledo, Ohio Product: Ohio-based polysilicon startup focusing on modular production. Coordinates: 46.440613, -122.847838 Show Map...

  15. Hydrogen Evolution at Si-based Metal-Insulator-Semiconductor...

    Office of Scientific and Technical Information (OSTI)

    Hydrogen Evolution at Si-based Metal-Insulator-Semiconductor Photoelectrodes Enhanced by Inversion Channel Charge Collection and Hydrogen Spillover Citation Details In-Document...

  16. Nanocrystalline SiC and Ti3SiC2 Alloys for Reactor Materials: Diffusion of Fission Product Surrogates

    SciTech Connect (OSTI)

    Henager, Charles H.; Jiang, Weilin

    2014-11-01

    MAX phases, such as titanium silicon carbide (Ti3SiC2), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti3SiC2 has been suggested in the literature as a possible fuel cladding material. Prior to the application, it is necessary to investigate diffusivities of fission products in the ternary compound at elevated temperatures. This study attempts to obtain relevant data and make an initial assessment for Ti3SiC2. Ion implantation was used to introduce fission product surrogates (Ag and Cs) and a noble metal (Au) in Ti3SiC2, SiC, and a dual-phase nanocomposite of Ti3SiC2/SiC synthesized at PNNL. Thermal annealing and in-situ Rutherford backscattering spectrometry (RBS) were employed to study the diffusivity of the various implanted species in the materials. In-situ RBS study of Ti3SiC2 implanted with Au ions at various temperatures was also performed. The experimental results indicate that the implanted Ag in SiC is immobile up to the highest temperature (1273 K) applied in this study; in contrast, significant out-diffusion of both Ag and Au in MAX phase Ti3SiC2 occurs during ion implantation at 873 K. Cs in Ti3SiC2 is found to diffuse during post-irradiation annealing at 973 K, and noticeable Cs release from the sample is observed. This study may suggest caution in using Ti3SiC2 as a fuel cladding material for advanced nuclear reactors operating at very high temperatures. Further studies of the related materials are recommended.

  17. Ceramic Technology Project database: September 1990 summary report. [SiC, SiN, whisker-reinforced SiN, ZrO-toughened aluminas, zirconias, joints

    SciTech Connect (OSTI)

    Keyes, B.L.P.

    1992-06-01

    Data generated within the Ceramic Technology Project (CTP) represent a valuable resource for both research and industry. The CTP database was created to provide easy access to this information in electronic and hardcopy forms by using a computerized database and by issuing periodic hardcopy reports on the database contents. This report is the sixth in a series of semiannual database summaries and covers recent additions to the database, including joined brazed specimen test data. It covers 1 SiC, 34 SiN, 10 whisker-reinforced SiN, 2 zirconia-toughened aluminas, 8 zirconias, and 34 joints.

  18. Nanocrystalline SiC and Ti3SiC2 Alloys for Reactor Materials: Thermal and Mechanical Properties

    SciTech Connect (OSTI)

    Henager, Charles H.; Alvine, Kyle J.; Roosendaal, Timothy J.; Shin, Yongsoon; Nguyen, Ba Nghiep; Borlaug, Brennan A.; Jiang, Weilin

    2014-04-01

    SiC-polymers (pure polycarbosilane and polycarbosilane filled with SiC-particles) are being combined with Si and TiC powders to create a new class of polymer-derived ceramics for consideration as advanced nuclear materials in a variety of applications. Compared to pure SiC these materials have increased fracture toughness with only slightly reduced thermal conductivity. Future work with carbon nanotube (CNT) mats will be introduced with the potential to increase the thermal conductivity and the fracture toughness. At present, this report documents the fabrication of a new class of monolithic polymer derived ceramics, SiC + SiC/Ti3SiC2 dual phase materials. The fracture toughness of the dual phase material was measured to be significantly greater than Hexoloy SiC using indentation fracture toughness testing. However, thermal conductivity of the dual phase material was reduced compared to Hexoloy SiC, but was still appreciable, with conductivities in the range of 40 to 60 W/(m K). This report includes synthesis details, optical and scanning electron microscopy images, compositional data, fracture toughness, and thermal conductivity data.

  19. Photoluminescence of as-grown and thermal annealed SiO{sub x}/Si-nanocrystals heterolayers grown by reactive rf sputtering

    SciTech Connect (OSTI)

    Mota-Pineda, E.; Melendez-Lira, M.; Zapata-Torres, M.; Angel, P. del; Perez-Centeno, A.; Santana-Aranda, M. A.; Jimenez-Sandoval, S.

    2010-11-15

    SiO{sub x}/Si-nanocrystals (Si NCs) heterolayers were fabricated employing a rf magnetron sputtering system. The synthesis process, through modification of the oxygen partial pressure of the plasma, promotes the synthesis of stoichiometric SiO{sub 2} layers and affect the Si NCs layer giving place to SiO{sub x}/Si NCs (1.64Si NCs. Thermal annealing at 1100 deg. C promoted the SiO{sub 2} stoichiometry in the interface and the crystallization of more Si NCs. The results allow us to clearly identify the origin of the PL bands; indicating that the near-infrared emission is related to the nonstoichiometric oxide while the red and green bands are originated in Si NCs.

  20. Improvement of magnetic and structural stabilities in high-quality Co{sub 2}FeSi{sub 1−x}Al{sub x}/Si heterointerfaces

    SciTech Connect (OSTI)

    Yamada, S.; Tanikawa, K.; Oki, S.; Kawano, M.; Miyao, M.; Hamaya, K.

    2014-08-18

    We study high-quality Co{sub 2}FeSi{sub 1−x}Al{sub x} Heusler compound/Si (0 ≤ x ≤ 1) heterointerfaces for silicon (Si)-based spintronic applications. In thermal treatment conditions, the magnetic and structural stabilities of the Co{sub 2}FeSi{sub 1−x}Al{sub x}/Si heterointerfaces are improved with increasing x in Co{sub 2}FeSi{sub 1−x}Al{sub x}. Compared with L2{sub 1}-ordered Co{sub 2}FeSi/Si, B2-ordered Co{sub 2}FeAl/Si can suppress the diffusion of Si atoms into the Heusler-compound structure. This experimental study will provide an important knowledge for applications in Si-based spin transistors with metallic source/drain contacts.

  1. Flex Fuel Optimized SI and HCCI Engine

    SciTech Connect (OSTI)

    Zhu, Guoming; Schock, Harold; Yang, Xiaojian; Huisjen, Andrew; Stuecken, Tom; Moran, Kevin; Zhen, Ron; Zhang, Shupeng

    2013-09-30

    The central objective of the proposed work is to demonstrate an HCCI (homogeneous charge compression ignition) capable SI (spark ignited) engine that is capable of fast and smooth mode transition between SI and HCCI combustion modes. The model-based control technique was used to develop and validate the proposed control strategy for the fast and smooth combustion mode transition based upon the developed control-oriented engine; and an HCCI capable SI engine was designed and constructed using production ready two-step valve-train with electrical variable valve timing actuating system. Finally, smooth combustion mode transition was demonstrated on a metal engine within eight engine cycles. The Chrysler turbocharged 2.0L I4 direct injection engine was selected as the base engine for the project and the engine was modified to fit the two-step valve with electrical variable valve timing actuating system. To develop the model-based control strategy for stable HCCI combustion and smooth combustion mode transition between SI and HCCI combustion, a control-oriented real-time engine model was developed and implemented into the MSU HIL (hardware-in-the-loop) simulation environment. The developed model was used to study the engine actuating system requirement for the smooth and fast combustion mode transition and to develop the proposed mode transition control strategy. Finally, a single cylinder optical engine was designed and fabricated for studying the HCCI combustion characteristics. Optical engine combustion tests were conducted in both SI and HCCI combustion modes and the test results were used to calibrate the developed control-oriented engine model. Intensive GT-Power simulations were conducted to determine the optimal valve lift (high and low) and the cam phasing range. Delphi was selected to be the supplier for the two-step valve-train and Denso to be the electrical variable valve timing system supplier. A test bench was constructed to develop control strategies for the electrical variable valve timing (VVT) actuating system and satisfactory electrical VVT responses were obtained. Target engine control system was designed and fabricated at MSU for both single-cylinder optical and multi-cylinder metal engines. Finally, the developed control-oriented engine model was successfully implemented into the HIL simulation environment. The Chrysler 2.0L I4 DI engine was modified to fit the two-step vale with electrical variable valve timing actuating system. A used prototype engine was used as the base engine and the cylinder head was modified for the two-step valve with electrical VVT actuating system. Engine validation tests indicated that cylinder #3 has very high blow-by and it cannot be reduced with new pistons and rings. Due to the time constraint, it was decided to convert the four-cylinder engine into a single cylinder engine by blocking both intake and exhaust ports of the unused cylinders. The model-based combustion mode transition control algorithm was developed in the MSU HIL simulation environment and the Simulink based control strategy was implemented into the target engine controller. With both single-cylinder metal engine and control strategy ready, stable HCCI combustion was achived with COV of 2.1% Motoring tests were conducted to validate the actuator transient operations including valve lift, electrical variable valve timing, electronic throttle, multiple spark and injection controls. After the actuator operations were confirmed, 15-cycle smooth combustion mode transition from SI to HCCI combustion was achieved; and fast 8-cycle smooth combustion mode transition followed. With a fast electrical variable valve timing actuator, the number of engine cycles required for mode transition can be reduced down to five. It was also found that the combustion mode transition is sensitive to the charge air and engine coolant temperatures and regulating the corresponding temperatures to the target levels during the combustion mode transition is the key for a smooth combustion mode transition. As a summary, the proposed combust

  2. Si?-implanted Si-wire waveguide photodetectors for the mid-infrared

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Souhan, Brian; Lu, Ming; Grote, Richard R.; Chen, Christine P.; Huang, Hsu-Cheng; Driscoll, Jeffrey B.; Stein, Aaron; Bakhru, Hassaram; Bergman, Keren; Green, William M. J.; et al

    2014-10-28

    CMOS-compatible Si?-implanted Si-waveguide p-i-n photodetectors operating at room temperature and at mid-infrared wavelengths from 2.2 to 2.3 m are demonstrated. Responsivities of 9.9 2.0 mA/W are measured at a 5 V reverse bias with an estimated internal quantum efficiency of 2.7 4.5%. The dark current is found to vary from a few microamps down to less than a nanoamp after a post-implantation annealing of 350C. The measured photocurrent dependence on input power shows a linear correspondence over more than three decades, and the frequency response of a 250 m-length p-i-n device is measured to be ~1.7 GHz formorea wavelength of ? = 2.2 m, thus potentially opening up new communication bands for photonic integrated circuits.less

  3. Electronic structures of GeSi nanoislands grown on pit-patterned Si(001) substrate

    SciTech Connect (OSTI)

    Ye, Han Yu, Zhongyuan

    2014-11-15

    Patterning pit on Si(001) substrate prior to Ge deposition is an important approach to achieve GeSi nanoislands with high ordering and size uniformity. In present work, the electronic structures of realistic uncapped pyramid, dome, barn and cupola nanoislands grown in (105) pits are systematically investigated by solving Schrdinger equation for heavy-hole, which resorts to inhomogeneous strain distribution and nonlinear composition-dependent band parameters. Uniform, partitioned and equilibrium composition profile (CP) in nanoisland and inverted pyramid structure are simulated separately. We demonstrate the huge impact of composition profile on localization of heavy-hole: wave function of ground state is confined near pit facets for uniform CP, at bottom of nanoisland for partitioned CP and at top of nanoisland for equilibrium CP. Moreover, such localization is gradually compromised by the size effect as pit filling ratio or pit size decreases. The results pave the fundamental guideline of designing nanoislands on pit-patterned substrates for desired applications.

  4. Formation and incorporation of SiF{sub 4} molecules in F-implanted preamorphized Si

    SciTech Connect (OSTI)

    De Salvador, D.; Bisognin, G.; Napolitani, E.; Mastromatteo, M.; Baggio, N.; Carnera, A.; Boscherini, F.; Cristiano, F.

    2009-09-07

    The local structure of fluorine incorporated in crystalline silicon following solid phase epitaxial regrowth was investigated by means of x-ray absorption spectroscopy at the F K-edge. We clearly demonstrate that most F is found in SiF{sub 4} molecules in the crystalline matrix. A kinetic pathway, which explains our observation and which is also able to rationalize previous results in a common and coherent framework, is proposed.

  5. Enhancement and Suppression of Photocurrent in Si Photodiodes by

    Office of Scientific and Technical Information (OSTI)

    Nanoparticles and Nonlinear Terahertz Superconducting Metamaterials (Technical Report) | SciTech Connect Enhancement and Suppression of Photocurrent in Si Photodiodes by Nanoparticles and Nonlinear Terahertz Superconducting Metamaterials Citation Details In-Document Search Title: Enhancement and Suppression of Photocurrent in Si Photodiodes by Nanoparticles and Nonlinear Terahertz Superconducting Metamaterials Authors: Grady, Nathaniel [1] + Show Author Affiliations Los Alamos National

  6. Scattering mechanisms in shallow undoped Si/SiGe quantum wells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Laroche, Dominique; Huang, S. -H.; Nielsen, Erik; Chuang, Y.; Li, J. -Y.; Liu, C. W.; Lu, Tzu -Ming

    2015-10-07

    We report the magneto-transport study and scattering mechanism analysis of a series of increasingly shallow Si/SiGe quantum wells with depth ranging from ~ 100 nm to ~ 10 nm away from the heterostructure surface. The peak mobility increases with depth, suggesting that charge centers near the oxide/semiconductor interface are the dominant scattering source. The power-law exponent of the electron mobility versus density curve, μ ∝ nα, is extracted as a function of the depth of the Si quantum well. At intermediate densities, the power-law dependence is characterized by α ~ 2.3. At the highest achievable densities in the quantum wellsmore » buried at intermediate depth, an exponent α ~ 5 is observed. Lastly, we propose and show by simulations that this increase in the mobility dependence on the density can be explained by a non-equilibrium model where trapped electrons smooth out the potential landscape seen by the two-dimensional electron gas.« less

  7. Mechanistic Selection and Growth of Twinned Bicrystalline Primary Si in Near Eutectic Al-Si Alloys

    SciTech Connect (OSTI)

    Choonho Jung

    2006-12-12

    Morphological evolution and selection of angular primary silicon is investigated in near-eutectic Al-Si alloys. Angular silicon arrays are grown directionally in a Bridgman furnace at velocities in the regime of 10{sup -3} m/sec and with a temperature gradient of 7.5 x 10{sup 3} K/m. Under these conditions, the primary Si phase grows as an array of twinned bicrystalline dendrites, where the twinning gives rise to a characteristic 8-pointed star-shaped primary morphology. While this primary Si remains largely faceted at the growth front, a complex structure of coherent symmetric twin boundaries enables various adjustment mechanisms which operate to optimize the characteristic spacings within the primary array. In the work presented here, this primary silicon growth morphology is examined in detail. In particular, this thesis describes the investigation of: (1) morphological selection of the twinned bicrystalline primary starshape morphology; (2) primary array behavior, including the lateral propagation of the starshape grains and the associated evolution of a strong <100> texture; (3) the detailed structure of the 8-pointed star-shaped primary morphology, including the twin boundary configuration within the central core; (4) the mechanisms of lateral propagation and spacing adjustment during array evolution; and (5) the thermosolutal conditions (i.e. operating state) at the primary growth front, including composition and phase fraction in the vicinity of the primary tip.

  8. Hot metal Si control at Kwangyang blast furnaces

    SciTech Connect (OSTI)

    Hur, N.S.; Cho, B.R.; Kim, G.Y.; Choi, J.S.; Kim, B.H.

    1995-12-01

    Studies of Si transfer in blast furnaces have shown that the Si level in pig iron is influenced more by the reaction of silicon oxide gas generation in the raceway than the chemical reaction between hot metal and slag at the drop zone. Specifications require a Si content of pig iron below 0.15% at the Kwangyang Works, but the use of soft coking coal in the blend for coke ovens, high pulverized coal injection rate into the blast furnace, and the application of lower grade iron ore has resulted in the need to develop methods to control Si in hot metal. In this paper, the results of in furnace Si control and the desiliconization skills at the casthouse floor are described.

  9. Resonant tunneling with high peak to valley current ratio in SiO{sub 2}/nc-Si/SiO{sub 2} multi-layers at room temperature

    SciTech Connect (OSTI)

    Chen, D. Y.; Sun, Y.; He, Y. J.; Xu, L.; Xu, J.

    2014-01-28

    We have investigated carrier transport in SiO{sub 2}/nc-Si/SiO{sub 2} multi-layers by room temperature current-voltage measurements. Resonant tunneling signatures accompanied by current peaks are observed. Carrier transport in the multi-layers were analyzed by plots of ln(I/V{sup 2}) as a function of 1/V and ln(I) as a function of V{sup 1/2}. Results suggest that besides films quality, nc-Si and barrier sub-layer thicknesses are important parameters that restrict carrier transport. When thicknesses are both small, direct tunneling dominates carrier transport, resonant tunneling occurs only at certain voltages and multi-resonant tunneling related current peaks can be observed but with peak to valley current ratio (PVCR) values smaller than 1.5. When barrier thickness is increased, trap-related and even high field related tunneling is excited, causing that multi-current peaks cannot be observed clearly, only one current peak with higher PVCR value of 7.7 can be observed. While if the thickness of nc-Si is large enough, quantum confinement is not so strong, a broad current peak with PVCR value as high as 60 can be measured, which may be due to small energy difference between the splitting energy levels in the quantum dots of nc-Si. Size distribution in a wide range may cause un-controllability of the peak voltages.

  10. Scale Up of Si/Si0.8GE0.2 and B4C/B9C Superlattices for Harvesting...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Scale Up of SiSi0.8GE0.2 and B4CB9C Superlattices for Harvesting of Waste Heat in Diesel Engines Scale Up of SiSi0.8GE0.2 and B4CB9C Superlattices for Harvesting of Waste Heat ...

  11. Water absorption in thermally grown oxides on SiC and Si: Bulk oxide and interface properties

    SciTech Connect (OSTI)

    Liu, Gang; Xu, Can; Feldman, Leonard C.; Yakshinskiy, Boris; Wielunski, Leszek; Gustafsson, Torgny; Bloch, Joseph; Dhar, Sarit

    2014-11-10

    We combine nuclear reaction analysis and electrical measurements to study the effect of water exposure (D{sub 2}O) on the n-type 4H-SiC carbon face (0001{sup }) MOS system and to compare to standard silicon based structures. We find that: (1) The bulk of the oxides on Si and SiC behave essentially the same with respect to deuterium accumulation; (2) there is a significant difference in accumulation of deuterium at the semiconductor/dielectric interface, the SiC C-face structure absorbs an order of magnitude more D than pure Si; (3) standard interface passivation schemes such as NO annealing greatly reduce the interfacial D accumulation; and (4) the effective interfacial charge after D{sub 2}O exposure is proportional to the total D amount at the interface.

  12. Ultrathin nanosheets of CrSiTe3: A semiconducting two-dimensional...

    Office of Scientific and Technical Information (OSTI)

    In this work we for the first time exfoliate the CrSiTe3, a bulk ferromagnetic semiconductor, to mono- and few-layer 2D crystals onto a SiSiO2 substrate. The Raman spectra show ...

  13. Reaction of Si(111) Surface with Saturated Hydrocarbon

    SciTech Connect (OSTI)

    Suryana, Risa; Nakahara, Hitoshi; Saito, Yahachi; Ichimiya, Ayahiko

    2011-12-10

    Reaction of Si(111) surface with saturated hydrocarbon such as methane (CH{sub 4}) and ethane (C{sub 2}H{sub 6}) was carried out in a gas source molecular beam epitaxy (GSMBE). After carbonization, structures formed on the surface were observed by in situ reflection high-energy electron diffraction (RHEED). Structures transition formed on the surface were 7x7, {delta}-7x7, 1x1, and SiC structures. In the case of CH{sub 4}, the Si surfaces were carbonized at 800 deg. C for 120 min (7.2x10{sup 4} L) with a W-filament of 2800 deg. C, and SiC layers were obtained. In the case of C{sub 2}H{sub 6}, the mixture of 7x7 and SiC structure was observed. Decomposition of hydrocarbon was characterized in quadrupole mass spectroscopy (QMS) measurements. An atomic force microscopy (AFM) image of the mixture of 7x7 and SiC shows a wandering shape. Whereas, the SiC layer shows a regular step. This result seems to be related to the different in the amount of CH{sub 3} molecules on the surface.

  14. Magnetic order and crystal structure study of YNi{sub 4}Si-type NdNi{sub 4}Si

    SciTech Connect (OSTI)

    Yao, Jinlei; Isnard, O.; Morozkin, A.V.; Ivanova, T.I.; Koshkid'ko, Yu.S.; Bogdanov, A.E.; Nikitin, S.A.; Suski, W.

    2015-02-15

    Magnetic measurements and neutron powder diffraction investigation of the magnetic structure of the orthorhombic YNi{sub 4}Si-type (space group Cmmm) NdNi{sub 4}Si compound are presented. The magnetocaloric effect of NdNi{sub 4}Si is calculated in terms of the isothermal magnetic entropy change and it reaches the maximum value of –3.3 J/kg K for a field change of 50 kOe near T{sub C}=12 K. Below ∼12 K, NdNi{sub 4}Si exhibits a commensurate b-axis collinear ferromagnetic ordering with the Cmm′m magnetic space group in a zero magnetic field. At 1.5 K, the neodymium atoms have the magnetic moment of 2.37(5) μ{sub B}. The orthorhombic crystal structure and its thermal evolution are discussed in comparison with the CaCu{sub 5}-type compound. - Graphical abstract: The NdNi{sub 4}Si supplement the series of the orthorhombic derivative of the CaCu{sub 5}-type, namely the YNi{sub 4}Si-type, RNi{sub 4}Si compounds (R=Y, La, Ce, Sm, Gd–Ho). Below ∼12 K in a zero applied magnetic field, NdNi{sub 4}Si exhibits a commensurate b-axis collinear ferromagnetic ordering with the Cmm′m magnetic space group. Compared to the CaCu{sub 5}-type NdNi{sub 4}Si compound, the YNi{sub 4}Si-type counterpart has the relatively high ferromagnetic ordering temperature (9.2 K vs. 12 K), the small magnetocaloric effect (–7.3 J/kg K vs. –3.3 J/kg K for ∆H=50 kOe), and the large magnetic anisotropy at low temperatures. In contrast with CaCu{sub 5}-type NdNi{sub 4}Si, YNi{sub 4}Si-type NdNi{sub 4}Si shows distinct hysteresis loop at 2 K.We suggest that orthorhombic distortion may be used as a prospective route for optimization of permanent magnetic properties in the family of CaCu{sub 5}-type rare earth materials. - Highlights: • Below ∼12 K the YNi{sub 4}Si-type NdNi{sub 4}Si shows a ferromagnetic ordering. • MCE of NdNi{sub 4}Si reaches value of –3.3 J/kg K in 0–50 kOe near Curie point. • NdNi{sub 4}Si exhibits b-axis ferromagnetic order with the Cmm′m magnetic space group. • Contrary to CaCu{sub 5}-type, YNi{sub 4}Si-type NdNi{sub 4}Si shows hysteresis loop at 2 K.

  15. Magnetic and magnetothermodynamic properties of Ho5Si4 (Conference) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect and magnetothermodynamic properties of Ho5Si4 Citation Details In-Document Search Title: Magnetic and magnetothermodynamic properties of Ho5Si4 The magnetic and magnetocaloric properties of Ho{sub 5}Si{sub 4} have been investigated. The compound undergoes a second order ferromagnetic transition at 76 K (T{sub c}) and a spin reorientation transition at about 15 K. The temperature dependencies of heat capacity data measured in various magnetic fields corroborate the second

  16. 14.11.05 RH Stabilized Si Microwire - JCAP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Stabilized Si Microwire Arrays for Solar-Driven H2O Oxidation Shaner, M. R., Hu, S., Sun, K. & Lewis, N. S. Stabilization of Si microwire arrays for solar-driven H2O oxidation to O2(g) in 1.0 M KOH(aq) using conformal coatings of amorphous TiO2. Energy & Environmental Science 8, 203-207, DOI: 10.1039/c4ee03012e (2015). Scientific Achievement Atomic-layer deposition of TiO2combined with sputtering of NiCrOxoxygen-evolution catalyst on Si microwires yields robust microwire-array

  17. Theoretical investigations of defects in a Si-based digital ferromagne...

    Office of Scientific and Technical Information (OSTI)

    in a Si-based digital ferromagnetic heterostructure - a spintronic material Citation Details In-Document Search Title: Theoretical investigations of defects in a Si-based ...

  18. Asia Silicon Qinghai Co Ltd aka Asia Si Material | Open Energy...

    Open Energy Info (EERE)

    Silicon Qinghai Co Ltd aka Asia Si Material Jump to: navigation, search Name: Asia Silicon (Qinghai) Co Ltd (aka Asia Si Material) Place: Xining, Qinghai Province, China Zip:...

  19. A low thermal impact annealing process for SiO{sub 2}-embedded Si nanocrystals with optimized interface quality

    SciTech Connect (OSTI)

    Hiller, Daniel Gutsch, Sebastian; Hartel, Andreas M.; Zacharias, Margit; Lper, Philipp; Gebel, Thoralf

    2014-04-07

    Silicon nanocrystals (Si NCs) for 3rd generation photovoltaics or optoelectronic applications can be produced by several industrially compatible physical or chemical vapor deposition technologies. A major obstacle for the integration into a fabrication process is the typical annealing to form and crystallize these Si quantum dots (QDs) which involves temperatures ?1100??C for 1?h. This standard annealing procedure allows for interface qualities that correspond to more than 95% dangling bond defect free Si NCs. We study the possibilities to use rapid thermal annealing (RTA) and flash lamp annealing to crystallize the Si QDs within seconds or milliseconds at high temperatures. The Si NC interface of such samples exhibits huge dangling bond defect densities which makes them inapplicable for photovoltaics or optoelectronics. However, if the RTA high temperature annealing is combined with a medium temperature inert gas post-annealing and a H{sub 2} passivation, luminescent Si NC fractions of up to 90% can be achieved with a significantly reduced thermal load. A new figure or merit, the relative dopant diffusion length, is introduced as a measure for the impact of a Si NC annealing procedure on doping profiles of device structures.

  20. Stereochemical effects in the gas-phase pinacol rearrangement. 2. Ring contraction versus methyl migration in cis- and trans-1,2-dimethylcyclohexane-1,2-diol

    SciTech Connect (OSTI)

    de Petris, G.; Giacomello, P.; Pizzabiocca, A.; Renzi, G.; Speranza, M.

    1988-02-17

    The gas-phase pinacol rearrangement of cis- and trans-1,2-dimethylcyclohexane-1,2-diols, promoted by D/sub 3//sup +/, CH/sub 5//sup +//C/sub 2/H/sub 5//sup +/ and t-C/sub 4/H/sub 9//sup +/ ions, was studied by mass spectrometric and radiolytic methods in the pressure range 0.5-760 Torr. When product isomerization is inhibited, by using N(CH/sub 3/)/sub 3/ as a trapping reagent at high pressure, mixtures of 2,2-dimethylcyclohexanone and 1-acetyl-1-methylcyclopentane were recovered from the reaction. In methane, the trend of the measured relative rates for ring contraction (k/sub 5/), methyl or hydroxyl group migration (k/sub 6/) versus the rearrangement rate of pincaol itself (k/sub p/), is k/sub 6/(trans) approx. k/sub 5/(trans) greater than or equal to k/sub 5/(cis) > k/sub 6/(cis) greater than or equal to k/sub p/. No evidence for the formation of an intermediate carbenium ion was found. Stereochemical aspects of the mechanism are discussed and compared with solution data.

  1. SiXtron Advanced Materials Inc | Open Energy Information

    Open Energy Info (EERE)

    to: navigation, search Name: SiXtron Advanced Materials Inc Place: Dorval, Quebec, Canada Zip: H9P 1J1 Product: Canadian manufacturer of anti-reflective coating capital...

  2. Crystallization from high temperature solutions of Si in copper

    DOE Patents [OSTI]

    Ciszek, Theodore F.

    1994-01-01

    A liquid phase epitaxy method for forming thin crystalline layers of device quality silicon having less than 5X10.sup.16 Cu atoms/cc impurity, comprising: preparing a saturated liquid solution melt of Si in Cu at about 16% to about 90% wt. Si at a temperature range of about 800.degree. C. to about 1400.degree. C. in an inert gas; immersing a substrate in the saturated solution melt; supersaturating the solution by lowering the temperature of the saturated solution melt and holding the substrate immersed in the solution melt for a period of time sufficient to cause growing Si to precipitate out of the solution to form a crystalline layer of Si on the substrate; and withdrawing the substrate from the solution.

  3. Theoretical investigations of two Si-based spintronic materials

    SciTech Connect (OSTI)

    Fong, C Y; Snow, R; Shaughnessy, M; Pask, J E; Yang, L H

    2007-08-03

    Two Si-based spintronic materials, a Mn-Si digital ferromagnetic heterostructure ({delta}-layer of Mn doped in Si) with defects and dilutely doped Mn{sub x}Si{sub 1-x} alloy are investigated using a density-functional based approach. We model the heterostructure and alloy with a supercell of 64 atoms and examine several configurations of the Mn atoms. We find that 25% substitutional defects without vacancies in the {delta} layer diminishes half metallicity of the DFH substantially. For the alloy, the magnetic moment M ranges from 1.0-9.0 {mu}{sub B}/unit-cell depending on impurity configuration and concentration. Mn impurities introduce a narrow band of localized states near E{sub F}. These alloys are not half metals though their moments are integer. We explain the substantially different magnetic moments.

  4. SiLas GmbH | Open Energy Information

    Open Energy Info (EERE)

    Product: Laser technology development enterprise specialising in the processing of thin-film silicon coating. References: SiLas GmbH1 This article is a stub. You can help...

  5. Silicon Carbide (SiC) MOSFET | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    months to fabricate a SiC power device, so cracking the MOSFET code was far from straightforward. They had to break the process down step by step and ingredient by ingredient to...

  6. Thermal decomposition of silane to form hydrogenated amorphous Si film

    DOE Patents [OSTI]

    Strongin, Myron; Ghosh, Arup K.; Wiesmann, Harold J.; Rock, Edward B.; Lutz, III, Harry A.

    1980-01-01

    This invention relates to hydrogenated amorphous silicon produced by thermally decomposing silano (SiH.sub.4) or other gases comprising H and Si, at elevated temperatures of about 1700.degree.-2300.degree. C., and preferably in a vacuum of about 10.sup.-8 to 10.sup.-4 torr, to form a gaseous mixture of atomic hydrogen and atomic silicon, and depositing said gaseous mixture onto a substrate outside said source of thermal decomposition to form hydrogenated amorphous silicon.

  7. Thermal decomposition of silane to form hydrogenated amorphous Si

    DOE Patents [OSTI]

    Strongin, M.; Ghosh, A.K.; Wiesmann, H.J.; Rock, E.B.; Lutz, H.A. III

    Hydrogenated amorphous silicon is produced by thermally decomposing silane (SiH/sub 4/) or other gases comprising H and Si, at elevated temperatures of about 1700 to 2300/sup 0/C, in a vacuum of about 10/sup -8/ to 10/sup -4/ torr. A gaseous mixture is formed of atomic hydrogen and atomic silicon. The gaseous mixture is deposited onto a substrate to form hydrogenated amorphous silicon.

  8. Low Reactivity SI Engine Lubricant Program | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Reactivity SI Engine Lubricant Program Low Reactivity SI Engine Lubricant Program Results showed that lubricant improvement allowed up to 4 degree improvement in spark advance at knock limited conditions resulting in potentially over 3 percent indicated efficiency improvement PDF icon deer11_alger.pdf More Documents & Publications Fuel & Lubricant Technologies Ionic Liquids as Novel Engine Lubricants or Lubricant Additives Fuel & Lubricant Technologies R&D

  9. Enhancement and Suppression of Photocurrent in Si Photodiodes by

    Office of Scientific and Technical Information (OSTI)

    Nanoparticles and Nonlinear Terahertz Superconducting Metamaterials (Technical Report) | SciTech Connect Enhancement and Suppression of Photocurrent in Si Photodiodes by Nanoparticles and Nonlinear Terahertz Superconducting Metamaterials Citation Details In-Document Search Title: Enhancement and Suppression of Photocurrent in Si Photodiodes by Nanoparticles and Nonlinear Terahertz Superconducting Metamaterials × You are accessing a document from the Department of Energy's (DOE) SciTech

  10. Scanning Photocurrent Microscopy of Si and Ge nanowires (Conference) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Conference: Scanning Photocurrent Microscopy of Si and Ge nanowires Citation Details In-Document Search Title: Scanning Photocurrent Microscopy of Si and Ge nanowires × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and technology. A paper copy

  11. Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Functional Polymer Binders | Department of Energy 3 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting PDF icon es147_wang_2013_o.pdf More Documents & Publications Vehicle Technologies Office Merit Review 2014: Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes and Functional Polymer Binders Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes and Functional Polymer

  12. SiAlON ceramic compositions and methods of fabrication

    DOE Patents [OSTI]

    O'Brien, M.H.; Park, B.H.

    1994-05-31

    A method of fabricating a SiAlON ceramic body includes: (a) combining quantities of Si[sub 3]N[sub 4], Al[sub 2]O[sub 3] and CeO[sub 2] to produce a mixture; (b) forming the mixture into a desired body shape; (c) heating the body to a densification temperature of from about 1,550 C to about 1,850 C; (d) maintaining the body at the densification temperature for a period of time effective to densify the body; (e) cooling the densified body to a devitrification temperature of from about 1,200 C to about 1,400 C; and (f) maintaining the densified body at the devitrification temperature for a period of time effective to produce a [beta][prime]-SiAlON crystalline phase in the body having elemental or compound form Ce incorporated in the [beta][prime]-SiAlON crystalline phase. Further, a SiAlON ceramic body comprises: (a) an amorphous phase; and (b) a crystalline phase, the crystalline phase comprising [beta][prime]-SiAlON having lattice substituted elemental or compound form Ce.

  13. Quantum confinement in Si and Ge nanostructures: Theory and experiment

    SciTech Connect (OSTI)

    Barbagiovanni, Eric G.; Lockwood, David J.; Simpson, Peter J.; Goncharova, Lyudmila V.

    2014-03-15

    The role of quantum confinement (QC) in Si and Ge nanostructures (NSs) including quantum dots, quantum wires, and quantum wells is assessed under a wide variety of fabrication methods in terms of both their structural and optical properties. Structural properties include interface states, defect states in a matrix material, and stress, all of which alter the electronic states and hence the measured optical properties. We demonstrate how variations in the fabrication method lead to differences in the NS properties, where the most relevant parameters for each type of fabrication method are highlighted. Si embedded in, or layered between, SiO{sub 2}, and the role of the sub-oxide interface states embodies much of the discussion. Other matrix materials include Si{sub 3}N{sub 4} and Al{sub 2}O{sub 3}. Si NSs exhibit a complicated optical spectrum, because the coupling between the interface states and the confined carriers manifests with varying magnitude depending on the dimension of confinement. Ge NSs do not produce well-defined luminescence due to confined carriers, because of the strong influence from oxygen vacancy defect states. Variations in Si and Ge NS properties are considered in terms of different theoretical models of QC (effective mass approximation, tight binding method, and pseudopotential method). For each theoretical model, we discuss the treatment of the relevant experimental parameters.

  14. Application of the Hartmann–Tran profile to precise experimental data sets of 12C2H2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Forthomme, D.; Cich, M. J.; Twagirayezu, S.; Hall, G. E.; Sears, T. J.

    2015-06-25

    Self- and nitrogen-broadened line shape data for the Pe(11) line of the ν₁ + ν₃ band of acetylene, recorded using a frequency comb-stabilized laser spectrometer, have been analyzed using the Hartmann–Tran profile (HTP) line shape model in a multispectrum fitting. In total, the data included measurements recorded at temperatures between 125 K and 296 K and at pressures between 4 and 760 Torr. New, sub-Doppler, frequency comb-referenced measurements of the positions of multiple underlying hot band lines have also been made. These underlying lines significantly affect the Pe(11) line profile at temperatures above 240 K and poorly known frequencies previouslymore » introduced errors into the line shape analyses. Thus, the behavior of the HTP model was compared to the quadratic speed dependent Voigt profile (QSDVP) expressed in the frequency and time domains. A parameter uncertainty analysis was carried out using a Monte Carlo method based on the estimated pressure, transmittance and frequency measurement errors. From the analyses, the Pe(11) line strength was estimated to be 1.2014(50) × 10-20 in cm.molecules⁻¹ units at 296 K with the standard deviation in parenthesis. For analyzing these data, we found that a reduced form of the HTP, equivalent to the QSDVP, was most appropriate because the additional parameters included in the full HTP were not well determined. As a supplement to this work, expressions for analytic derivatives and a lineshape fitting code written in Matlab for the HTP are available.« less

  15. Structural and photovoltaic properties of a-Si (SNc)/c-Si heterojunction fabricated by EBPVD technique

    SciTech Connect (OSTI)

    Demiro?lu, D.; Kazmanli, K.; Urgen, M.; Tatar, B.

    2013-12-16

    In last two decades sculptured thin films are very attractive for researches. Some properties of these thin films, like high porosity correspondingly high large surface area, controlled morphology; bring into prominence on them. Sculptured thin films have wide application areas as electronics, optics, mechanics, magnetic and chemistry. Slanted nano-columnar (SnC) thin films are a type of sculptured thin films. In this investigation SnC thin films were growth on n-type crystalline Si(100) and p-type crystalline Si(111) via ultra-high vacuum electron beam evaporation technique. The structural and morphological properties of the amorphous silicon thin films were investigated by XRD, Raman and FE-SEM analysis. According to the XRD and Raman analysis the structure of thin film was amorphous and FE-SEM analysis indicated slanted nano-columns were formed smoothly. Slanted nano-columns a-Si/c-Si heterojunction were prepared as using a photovoltaic device. In this regard we were researched photovoltaic properties of these heterojunction with current-voltage characterization under dark and illumination conditions. Electrical parameters were determined from the current-voltage characteristic in the dark conditions zero-bias barrier height ?{sub B0}?=?0.83?1.00eV; diode ideality factor ??=?11.71?10.73; series resistance R{sub s}?=?260?31.1 k? and shunt resistance R{sub sh}?=?25.71?63.5 M? SnC a-Si/n-Si and SnC a-Si/p-Si heterojunctions shows a pretty good photovoltaic behavior about 10{sup 3}- 10{sup 4} times. The obtained photovoltaic parameters are such as short circuit current density J{sub sc} 83-40 mA/m{sup 2}, open circuit voltage V{sub oc} 900-831 mV.

  16. Properties of Si{sub n}, Ge{sub n}, and Si{sub n}Ge{sub n} clusters

    SciTech Connect (OSTI)

    Dong, Yi; Rehman, Habib ur; Springborg, Michael

    2015-01-22

    The structures of Si{sub n}, Ge{sub n}, and Si{sub n}Ge{sub n} clusters with up to 44 atoms have been determined theoretically using an unbiased structure-optimization method in combination with a parametrized, density-functional description of the total energy for a given structure. By analyzing the total energy in detail, particularly stable clusters are identified. Moreover, general trends in the structures are identified with the help of specifically constructed descriptors.

  17. Hydrogen intercalation of single and multiple layer graphene synthesized on Si-terminated SiC(0001) surface

    SciTech Connect (OSTI)

    So?tys, Jakub; Piechota, Jacek; Ptasinska, Maria; Krukowski, Stanis?aw

    2014-08-28

    Ab initio density functional theory simulations were used to investigate the influence of hydrogen intercalation on the electronic properties of single and multiple graphene layers deposited on the SiC(0001) surface (Si-face). It is shown that single carbon layer, known as a buffer layer, covalently bound to the SiC substrate, is liberated after hydrogen intercalation, showing characteristic Dirac cones in the band structure. This is in agreement with the results of angle resolved photoelectron spectroscopy measurements of hydrogen intercalation of SiC-graphene samples. In contrast to that hydrogen intercalation has limited impact on the multiple sheet graphene, deposited on Si-terminated SiC surface. The covalently bound buffer layer is liberated attaining its graphene like structure and dispersion relation typical for multilayer graphene. Nevertheless, before and after intercalation, the four layer graphene preserved the following dispersion relations in the vicinity of K point: linear for (AAAA) stacking, direct parabolic for Bernal (ABAB) stacking and wizard hat parabolic for rhombohedral (ABCA) stacking.

  18. Effect of rapid thermal annealing temperature on the dispersion of Si nanocrystals in SiO{sub 2} matrix

    SciTech Connect (OSTI)

    Saxena, Nupur Kumar, Pragati; Gupta, Vinay

    2015-05-15

    Effect of rapid thermal annealing temperature on the dispersion of silicon nanocrystals (Si-NCs) embedded in SiO{sub 2} matrix grown by atom beam sputtering (ABS) method is reported. The dispersion of Si NCs in SiO{sub 2} is an important issue to fabricate high efficiency devices based on Si-NCs. The transmission electron microscopy studies reveal that the precipitation of excess silicon is almost uniform and the particles grow in almost uniform size upto 850 C. The size distribution of the particles broadens and becomes bimodal as the temperature is increased to 950 C. This suggests that by controlling the annealing temperature, the dispersion of Si-NCs can be controlled. The results are supported by selected area diffraction (SAED) studies and micro photoluminescence (PL) spectroscopy. The discussion of effect of particle size distribution on PL spectrum is presented based on tight binding approximation (TBA) method using Gaussian and log-normal distribution of particles. The study suggests that the dispersion and consequently emission energy varies as a function of particle size distribution and that can be controlled by annealing parameters.

  19. Composites of Upgraded Metallurgical Grade (UMG) Si with Photovoltaic (PV) Grade Si

    SciTech Connect (OSTI)

    Hovel, Harold; Prettyman, Kevin; Krause, Rainer; Dipankar, Roy

    2015-03-27

    At the beginning of this project 125 wafers of UMG material blended with non-UMG were obtained in the various blends; 50/50,70/30,80/20. 90/10 and 100% UMG. Solar grade , non-UMG material was used for comparison. Many techniques for starting substrate evaluation were used including lifetime, resitivity, SEM, IPCMS. Some degree of gettering was implemented by lengthening the time of phosphorous diffusion. The UMG/solar blends resulted in 14.5% -15% efficiencies, and even 100% UMG showed 14.5% values, not less than standard cells manufactured at the time and an encouraging result for the prospects of using UMG material due to the lower $/watt. A later decline in the cost of Si and an emphasis on reaching higher efficiencies in general led to a vanishing interest in the use of UMG.

  20. Absence of quantum confinement effects in the photoluminescence of Si{sub 3}N{sub 4}–embedded Si nanocrystals

    SciTech Connect (OSTI)

    Hiller, D. Zelenina, A.; Gutsch, S.; Zacharias, M.; Dyakov, S. A.; López-Conesa, L.; López-Vidrier, J.; Peiró, F.; Garrido, B.; Estradé, S.; Schnabel, M.; Weiss, C.; Janz, S.

    2014-05-28

    Superlattices of Si-rich silicon nitride and Si{sub 3}N{sub 4} are prepared by plasma-enhanced chemical vapor deposition and, subsequently, annealed at 1150 °C to form size-controlled Si nanocrystals (Si NCs) embedded in amorphous Si{sub 3}N{sub 4}. Despite well defined structural properties, photoluminescence spectroscopy (PL) reveals inconsistencies with the typically applied model of quantum confined excitons in nitride-embedded Si NCs. Time-resolved PL measurements demonstrate 10{sup 5} times faster time-constants than typical for the indirect band structure of Si NCs. Furthermore, a pure Si{sub 3}N{sub 4} reference sample exhibits a similar PL peak as the Si NC samples. The origin of this luminescence is discussed in detail on the basis of radiative defects and Si{sub 3}N{sub 4} band tail states in combination with optical absorption measurements. The apparent absence of PL from the Si NCs is explained conclusively using electron spin resonance data from the Si/Si{sub 3}N{sub 4} interface defect literature. In addition, the role of Si{sub 3}N{sub 4} valence band tail states as potential hole traps is discussed. Most strikingly, the PL peak blueshift with decreasing NC size, which is often observed in literature and typically attributed to quantum confinement (QC), is identified as optical artifact by transfer matrix method simulations of the PL spectra. Finally, criteria for a critical examination of a potential QC-related origin of the PL from Si{sub 3}N{sub 4}-embedded Si NCs are suggested.

  1. Nanocrystalline SiC and Ti3SiC2 Alloys for Reactor Materials: Annual Report

    SciTech Connect (OSTI)

    Henager, Charles H.; Alvine, Kyle J.; Roosendaal, Timothy J.; Shin, Yongsoon; Nguyen, Ba Nghiep; Borlaug, Brennan A.; Jiang, Weilin; Arreguin, Shelly A.

    2015-01-15

    A new dual-phase nanocomposite of Ti?SiC?/SiC is being synthesized using preceramic polymers, ceramic powders, and carbon nanotubes (CNTs) designed to be suitable for advanced nuclear reactors and perhaps as fuel cladding. The material is being designed to have superior fracture toughness compared to SiC, adequate thermal conductivity, and higher density than SiC/SiC composites. This annual report summarizes the progress towards this goal and reports progress in understanding certain aspects of the material behavior but some shortcomings in achieving full density or in achieving adequate incorporation of CNTs. The measured thermal conductivity is adequate and falls into an expected range based on SiC and Ti?SiC?. Part of this study makes an initial assessment for Ti?SiC? as a barrier to fission product transport. Ion implantation was used to introduce fission product surrogates (Ag and Cs) and a noble metal (Au) in Ti?SiC?, SiC, and a synthesized at PNNL. The experimental results indicate that the implanted Ag in SiC is immobile up to the highest temperature (1273 K) applied in this study; in contrast, significant out-diffusion of both Ag and Au in MAX phase Ti?SiC? occurs during ion implantation at 873 K. Cs in Ti?SiC? is found to diffuse during post-irradiation annealing at 973 K, and noticeable Cs release from the sample is observed. This study may suggest caution in using Ti?SiC? as a fuel cladding material for advanced nuclear reactors operating at very high temperatures. Progress is reported in thermal conductivity modeling of SiC-based materials that is relevant to this research, as is progress in modeling the effects of CNTs on fracture strength of SiC-based materials.

  2. Quantum wells on 3C-SiC/NH-SiC heterojunctions. Calculation of spontaneous polarization and electric field strength in experiments

    SciTech Connect (OSTI)

    Sbruev, I. S.; Sbruev, S. B.

    2010-10-15

    The results of experiments with quantum wells on 3C-SiC/4H-SiC and 3C-SiC/6H-SiC heterojunctions obtained by various methods are reconsidered. Spontaneous polarizations, field strengths, and energies of local levels in quantum wells on 3C-SiC/NH-SiC heterojunctions were calculated within a unified model. The values obtained are in agreement with the results of all considered experiments. Heterojunction types are determined. Approximations for valence band offsets on heterojunctions between silicon carbide polytypes and the expression for calculating local levels in quantum wells on the 3C-SiC/NH-SiC heterojunction are presented. The spontaneous polarizations and field strengths induced by spontaneous polarization on 3C-SiC/4H-SiC and 3C-SiC/6H-SiC heterojunctions were calculated as 0.71 and 0.47 C/m{sup 2} and 0.825 and 0.55 MV/cm, respectively.

  3. Temperature dependent transport characteristics of graphene/n-Si diodes

    SciTech Connect (OSTI)

    Parui, S.; Ruiter, R.; Zomer, P. J.; Wojtaszek, M.; Wees, B. J. van; Banerjee, T.

    2014-12-28

    Realizing an optimal Schottky interface of graphene on Si is challenging, as the electrical transport strongly depends on the graphene quality and the fabrication processes. Such interfaces are of increasing research interest for integration in diverse electronic devices as they are thermally and chemically stable in all environments, unlike standard metal/semiconductor interfaces. We fabricate such interfaces with n-type Si at ambient conditions and find their electrical characteristics to be highly rectifying, with minimal reverse leakage current (<10{sup ?10}?A) and rectification of more than 10{sup 6}. We extract Schottky barrier height of 0.69?eV for the exfoliated graphene and 0.83?eV for the CVD graphene devices at room temperature. The temperature dependent electrical characteristics suggest the influence of inhomogeneities at the graphene/n-Si interface. A quantitative analysis of the inhomogeneity in Schottky barrier heights is presented using the potential fluctuation model proposed by Werner and Gttler.

  4. Joining of beta-SiC by spark plasma sintering

    SciTech Connect (OSTI)

    Grasso, Salvatore; Tatarko, Peter; Rizzo, S.; Porwal, Harshit; Hu, Chunfeng; Katoh, Yutai; Salvo, M; Reece, Michael John; Ferraris, Monica

    2014-01-01

    Spark plasma sintering (SPS) was employed to join monolithic -SiC with or without titanium as intermediate joining material. Both the localizedand rapid heating contributed to the inherent energy saving of electric current assisted joining technique. The effects of uniaxial pressure and surfacepreparation were analyzed independently with respect to the flexural strength and the morphology of the joints. In particular samples polisheddown to 1 m and joined at 1900 C for 5 min achieved the strength of the as received material. The failure occurred outside the joining interface,confirming the optimum quality of the joint. Pressure in combination with surface preparation was necessary to achieve perfect adhesion and porefree direct joining of SiC. The use of Ti foil as a joining material and pressure allowed joining of unpolished SiC.

  5. Electronic and magnetic properties of Si substituted Fe3Ge

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shanavas, Kavungal Veedu; McGuire, Michael A.; Parker, David S.

    2015-09-23

    Using first principles calculations we studied the effect of Si substitution in the hexagonal Fe3Ge. We find the low temperature magnetic anisotropy in this system to be planar and originating mostly from the spin-orbit coupling in Fe-d states. Reduction of the unitcell volume reduces the in-plane magnetic anisotropy, eventually turning it positive which reorients the magnetic moments to the axial direction. We find that substituting Ge with the smaller Si ions also reduces the anisotropy, potentially enhancing the region of stability of the axial magnetization, which is beneficial for magnetic applications. Thus our experimental measurements on samples of Fe3Ge1–xSix confirmmore » these predictions and show that substitution of about 6% of the Ge with Si increases by approximately 35 K the temperature range over which anisotropy is uniaxial.« less

  6. N-V{sub Si}-related center in non-irradiated 6H SiC nanostructure

    SciTech Connect (OSTI)

    Bagraev, Nikolay; Danilovskii, Eduard; Gets, Dmitrii; Klyachkin, Leonid; Malyarenko, Anna; Kalabukhova, Ekaterina; Shanina, Bella; Savchenko, Dariya

    2014-02-21

    We present the first findings of the vacancy-related centers identified by the electron spin resonance (ESR) and electrically-detected (ED) ESR method in the non-irradiated 6H-SiC nanostructure. This planar 6H-SiC nanostructure represents the ultra-narrow p-type quantum well confined by the ?-barriers heavily doped with boron on the surface of the n-type 6H-SiC (0001) wafer. The EDESR method by measuring the only magnetoresistance of the 6H SiC nanostructure under the high frequency generation from the ?-barriers appears to allow the identification of the silicon vacancy centers as well as the triplet center with spin state S=1. The same triplet center that is characterized by the larger value of the zero-field splitting constant D and anisotropic g-factor is revealed by the ESR (X-band) method. The hyperfine (hf) lines in the ESR and EDESR spectra originating from the hf interaction with the {sup 14}N nucleus allow us to attribute this triplet center to the N-V{sub Si} defect.

  7. Heteroepitaxial Ge-on-Si by DC magnetron sputtering

    SciTech Connect (OSTI)

    Steglich, Martin; Schrempel, Frank; Fchsel, Kevin; Kley, Ernst-Bernhard; Patzig, Christian; Berthold, Lutz; Hche, Thomas; Tnnermann, Andreas; Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Albert-Einstein-Str. 7, 07745 Jena

    2013-07-15

    The growth of Ge on Si(100) by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380C. Typical Stransky-Krastanov growth is observed at 410C. At lower temperatures (320C), films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed.

  8. Recovery of Mo/Si multilayer coated optical substrates

    DOE Patents [OSTI]

    Baker, S.L.; Vernon, S.P.; Stearns, D.G.

    1997-12-16

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO{sub 2} overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates. 5 figs.

  9. Recovery of Mo/Si multilayer coated optical substrates

    DOE Patents [OSTI]

    Baker, Sherry L.; Vernon, Stephen P.; Stearns, Daniel G.

    1997-12-16

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO.sub.2 overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates.

  10. 15.08.07 RH Si Microwire Photoanode - JCAP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A High-Performance Si Microwire Photocathode Coupled with Ni-Mo Catalyst Shaner, M. R., McKone, J. R., Gray, H. B. & Lewis, N. S. Functional integration of Ni-Mo electrocatalysts with i microwire array photocathodes to simultaneously achieve high fill factors and light-limited photocurrent densities for solar-driven hydrogen evolution. Energy & Environmental Science, DOI: 10.1039/C5EE01076D (2015). Scientific Achievement We have designed and demonstrated a H2-evolving Si microwire

  11. Photoluminescence from Si nanocrystals exposed to a hydrogen plasma

    SciTech Connect (OSTI)

    Jung, Yoon-Jin; Yoon, Jong-Hwan; Elliman, R. G.; Wilkinson, A. R.

    2008-10-15

    Si nanocrystals embedded in SiO{sub 2} films were exposed to an atomic H plasma at different temperatures. Photoluminescence intensity from the nanocrystals increases with increasing exposure time, followed by saturation that depends on the exposure temperature. The saturation level depends on the final exposure temperature and shows no dependence on the thermal history of exposure. This behavior is shown to be consistent with a model in which the steady-state passivation level is determined by a balance between defect passivation and depassivation by H, with the activation energy for the passivation reaction being larger than that for the depassivation reaction.

  12. Synthesis of SiO{sub 2}/?-SiC/graphite hybrid composite by low temperature hot filament chemical vapor deposition

    SciTech Connect (OSTI)

    Zhang, Zhikun; Bi, Kaifeng; Liu, Yanhong; Qin, Fuwen; Liu, Hongzhu; Bian, Jiming; Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 ; Zhang, Dong; Miao, Lihua; Department of Computer and Mathematical Basic Teaching, Shenyang Medical College, Shenyan 110034

    2013-11-18

    ?-SiC thin films were synthesized directly on graphite by hot filament chemical vapor deposition at low temperature. SiH{sub 4} diluted in hydrogen was employed as the silicon source, while graphite was functioned as both substrate and carbon source for the as-grown ?-SiC films. X-ray diffraction and Fourier transform infrared analysis indicate that SiO{sub 2}/?-SiC/graphite hybrid composite was formed after post annealing treatment, and its crystalline quality can be remarkably improved under optimized annealing conditions. The possible growth mechanism was proposed based on in situ etching of graphite by reactive hydrogen radicals at the atomic level.

  13. Charge noise analysis of metal oxide semiconductor dual-gate Si/SiGe quantum point contacts

    SciTech Connect (OSTI)

    Kamioka, J.; Oda, S.; Kodera, T.; Takeda, K.; Obata, T.; Tarucha, S.

    2014-05-28

    The frequency dependence of conductance noise through a gate-defined quantum point contact fabricated on a Si/SiGe modulation doped wafer is characterized. The 1/f{sup 2} noise, which is characteristic of random telegraph noise, is reduced by application of a negative bias on the global top gate to reduce the local gate voltage. Direct leakage from the large global gate voltage also causes random telegraph noise, and therefore, there is a suitable point to operate quantum dot measurement.

  14. Light harvesting with Ge quantum dots embedded in SiO{sub 2} or Si{sub 3}N{sub 4}

    SciTech Connect (OSTI)

    Cosentino, Salvatore Raciti, Rosario; Simone, Francesca; Crupi, Isodiana; Terrasi, Antonio; Mirabella, Salvo; Sungur Ozen, Emel; Aydinli, Atilla; Mio, Antonio M.; Nicotra, Giuseppe; Turan, Rasit

    2014-01-28

    Germanium quantum dots (QDs) embedded in SiO{sub 2} or in Si{sub 3}N{sub 4} have been studied for light harvesting purposes. SiGeO or SiGeN thin films, produced by plasma enhanced chemical vapor deposition, have been annealed up to 850?C to induce Ge QD precipitation in Si based matrices. By varying the Ge content, the QD diameter can be tuned in the 39?nm range in the SiO{sub 2} matrix, or in the 12?nm range in the Si{sub 3}N{sub 4} matrix, as measured by transmission electron microscopy. Thus, Si{sub 3}N{sub 4} matrix hosts Ge QDs at higher density and more closely spaced than SiO{sub 2} matrix. Raman spectroscopy revealed a higher threshold for amorphous-to-crystalline transition for Ge QDs embedded in Si{sub 3}N{sub 4} matrix in comparison with those in the SiO{sub 2} host. Light absorption by Ge QDs is shown to be more effective in Si{sub 3}N{sub 4} matrix, due to the optical bandgap (0.91.6?eV) being lower than in SiO{sub 2} matrix (1.22.2?eV). Significant photoresponse with a large measured internal quantum efficiency has been observed for Ge QDs in Si{sub 3}N{sub 4} matrix when they are used as a sensitive layer in a photodetector device. These data will be presented and discussed, opening new routes for application of Ge QDs in light harvesting devices.

  15. Lithium diffusion at Si-C interfaces in silicon-graphene composites

    SciTech Connect (OSTI)

    Odbadrakh, Khorgolkhuu [Joint Institute for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); McNutt, N. W. [Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Nicholson, D. M. [Computational Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Department of Physics, University of North Carolina, Asheville, North Carolina 28804 (United States); Rios, O. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Keffer, D. J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)

    2014-08-04

    Models of intercalated Li and its diffusion in Si-Graphene interfaces are investigated using density functional theory. Results suggest that the presence of interfaces alters the energetics of Li binding and diffusion significantly compared to bare Si or Graphene surfaces. Our results show that cavities along reconstructed Si surface provide diffusion paths for Li. Diffusion barriers calculated along these cavities are significantly lower than penetration barriers to bulk Si. Interaction with Si surface results in graphene defects, creating Li diffusion paths that are confined along the cavities but have still lower barrier than in bulk Si.

  16. Interfacing the Ab initio multiple spawning method with electronic structure methods in GAMESS: Photodecay of trans-Azomethane

    SciTech Connect (OSTI)

    Gaenko, Alexander; DeFusco, Albert; Varganov, Sergey A.; Martnez, Todd J.; Gordon, Mark S.

    2014-10-20

    This work presents a nonadiabatic molecular dynamics study of the nonradiative decay of photoexcited trans-azomethane, using the ab initio multiple spawning (AIMS) program that has been interfaced with the General Atomic and Molecular Electronic Structure System (GAMESS) quantum chemistry package for on-the-fly electronic structure evaluation. The interface strategy is discussed, and the capabilities of the combined programs are demonstrated with a nonadiabatic molecular dynamics study of the nonradiative decay of photoexcited trans-azomethane. Energies, gradients, and nonadiabatic coupling matrix elements were obtained with the state-averaged complete active space self-consistent field method, as implemented in GAMESS. The influence of initial vibrational excitation on the outcome of the photoinduced isomerization is explored. Increased vibrational excitation in the CNNC torsional mode shortens the excited state lifetime. Depending on the degree of vibrational excitation, the excited state lifetime varies from ~60200 fs. As a result, these short lifetimes are in agreement with time-resolved photoionization mass spectroscopy experiments.

  17. Local structure order in Pd??Cu?Si?? liquid

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yue, G. Q.; Iowa State Univ., Ames, IA; Zhang, Y.; Sun, Y.; Shen, B.; Dong, F.; Wang, Z. Y.; Zhang, R. J.; Zheng, Y. X.; Kramer, M. J.; et al

    2015-02-05

    The short-range order (SRO) in Pd??Cu?Si?? liquid was studied by high energy x-ray diffraction and ab initio molecular dynamics (MD) simulations. The calculated pair correlation functions at different temperatures agree well with the experimental results. The partial pair correlation functions from ab intio MD simulations indicate that Si atoms prefer to be uniformly distributed while Cu atoms tend to aggregate. By performing structure analysis using Honeycutt-Andersen index, Voronoi tessellation, and atomic cluster alignment method, we show that the icosahedron and face-centered cubic SRO increase upon cooling. The dominant SRO is the Pd-centered Pd?Si? motif, namely the structure of which motifmoreis similar to the structure of Pd-centered clusters in the Pd?Si? crystal. The study further confirms the existence of trigonal prism capped with three half-octahedra that is reported as a structural unit in Pd-based amorphous alloys. The majority of Cu-centered clusters are icosahedra, suggesting that the presence of Cu is benefit to promote the glass forming ability.less

  18. Electrical properties of ternary Si-C-N ceramics

    SciTech Connect (OSTI)

    Haluschka, C.; Engel, C.; Riedel, R.

    1996-12-31

    Ternary Si-C-N ceramics were derived from silicon containing polymers by thermally induced hybrid processing. These silicon carbonitrides were investigated by impedance spectroscopy depending on the synthesis conditions. The electrical behavior correlates with the solid state reactions and phase transformations, which take place during the processing. It has also been shown that the electrical properties can be controlled in a wide range.

  19. Elastic scattering of /sup 16/O by /sup 28/Si

    SciTech Connect (OSTI)

    Shkolnik, V.; Dehnhard, D.; Franey, M.A.

    1983-08-01

    Differential cross sections were measured in small angular steps at forward angles for the elastic scattering of /sup 16/O from /sup 28/Si, /sup 29/Si, and /sup 30/Si at E/sub lab/ = 60 MeV and from /sup 28/Si at six other incident energies between 45 and 63 MeV. The angular position of a peak in the diffraction pattern at theta/sub c.m./approx. =75/sup 0/ was measured as a function of the incident energy between 55 and 63 MeV in 0.5 MeV steps. Close fits to these angular distributions and those of other authors at energies between 41 and 81 MeV, some spanning the whole angular range up to 180/sup 0/, and the excitation functions at 90/sup 0/ and 180/sup 0/, were obtained in an optical model analysis. A consistent description of the data was found by the use of a surface-transparent and parity-dependent potential with a real part able to generate a pocket in the total potential. The real and imaginary strengths depend quite strongly and smoothly on the incident energy. This potential shows a transition from surface transparency to strong absorption as E/sub lab/ approaches 81 MeV. The ambiguities in the strengths of the potential are discussed. The broad dispersive potential resonances which are present in several partial waves at every energy are also discussed and their relative importance is examined.

  20. Development of Solar Grade Silicon (SoG-Si) Feedstock by Recycling SoG-Si Wastes

    SciTech Connect (OSTI)

    Lifeng Zhang; Anping Dong; Lucas Nana Wiredu Damoah

    2013-01-24

    Experiment results of EM separation show that the non-metallic inclusions were successfully pushed to the boundary layer of the crucible under EM force. Larger frequency and smaller current generate smaller thickness of accumulated inclusions. More detailed EM separation experiments are undergoing to investigate the factors that affect the removal efficient of inclusions from SoG-Si

  1. Light-emitting Si nanostructures formed in SiO{sub 2} on irradiation with swift heavy ions

    SciTech Connect (OSTI)

    Kachurin, G. A. Cherkova, S. G.; Skuratov, V. A.; Marin, D. V.; Cherkov, A. G.

    2010-04-15

    SiO{sub 2} layers containing implanted excess Si are irradiated with Xe ions with an energy of 130 MeV and doses of 3 x 10{sup 12}-10{sup 14} cm{sup -2}. In the samples irradiated with a dose of 3 x 10{sup 12} cm{sup -2}, {approx}10{sup 12} cm{sup -2} segregated clusters 3-4 nm in dimension are detected by transmission electron microscopy. With increasing dose, the dimensions and number of these clusters increase. In the photoluminescence spectrum, a 660- to 680-nm band is observed, with the intensity dependent on the dose. After passivation of the sample with hydrogen at 500 deg. C, the band disappears, but a new {approx}780-nm band typical of Si nanocrystals becomes evident. On the basis of the entire set of data, it is concluded that the 660- to 680-nm band is associated with imperfect Si nanocrystals grown in the tracks of Xe ions due to high ionization losses. The nonmonotonic dependence of the photoluminescence intensity on the dose is attributed to the difference between the diameters of tracks and the diameters of the displacements' cascades responsible for defect formation.

  2. Ag Out-surface Diffusion In Crystalline SiC With An Effective SiO2 Diffusion Barrier

    SciTech Connect (OSTI)

    Xue, H.; Xiao, Haiyan Y.; Zhu, Zihua; Shutthanandan, V.; Snead, Lance L.; Boatner, Lynn A.; Weber, William J.; Zhang, Y.

    2015-09-01

    For applications of tristructural isotropic (TRISO) fuel particles in high temperature reactors, release of radioactive Ag isotope (110mAg) through the SiC coating layer is a safety concern. To understand the diffusion mechanism, Ag ion implantations near the surface and in the bulk were performed by utilizing different ion energies and energy-degrader foils. High temperature annealing was carried out on the as-irradiated samples to study the possible out-surface diffusion. Before and after annealing, Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) measurements were employed to obtain the elemental profiles of the implanted samples. The results suggest little migration of buried Ag in the bulk, and an out-diffusion of the implanted Ag in the near-surface region of single crystal SiC. It is also found that a SiO2 layer, which was formed during annealing, may serve as an effective barrier to reduce or prevent Ag out diffusion through the SiC coating layer.

  3. Research on the Hydrogen Passivation of Defects and Impurities in Si Relevant to Crystalline Si Solar Cell Materials: Final Report, 16 February 2000 -- 15 April 2003

    SciTech Connect (OSTI)

    Stavola, M.

    2003-09-01

    The goal of this experimental research program is to increase the understanding, at a microscopic level, of hydrogenation processes and passivation mechanisms for crystalline-Si photovoltaics. In our experiments, vibrational spectroscopy was used to study the properties of the interstitial H2 molecule in Si and the transition-metal-hydrogen complexes in Si. The interstitial H2 molecule is formed readily in Si when hydrogen is introduced. Our studies establish that interstitial H2 in Si behaves as a nearly free rotator, solving puzzles about the behavior of this defect that have persisted since the discovery of its vibrational spectrum. The transition metals are common impurities in Si that decrease the minority-carrier lifetime and degrade the efficiencies of solar cells. Therefore, the possibility that transition-metal impurities in Si might be passivated by hydrogen has long been of interest. Our studies of transition-metal-H complexes in Si help to establish the structural and electrical properties of a family of Pt-H complexes in Si, and have made the Pt-H complexes a model system for understanding the interaction of hydrogen with transition-metal impurities in Si.

  4. Comparative life-cycle energy payback analysis of multi-junction a-SiGe and nanocrystalline/a-Si modules

    SciTech Connect (OSTI)

    Fthenakis, V.; Kim, H.

    2010-07-15

    Despite the publicity of nanotechnologies in high tech industries including the photovoltaic sector, their life-cycle energy use and related environmental impacts are understood only to a limited degree as their production is mostly immature. We investigated the life-cycle energy implications of amorphous silicon (a-Si) PV designs using a nanocrystalline silicon (nc-Si) bottom layer in the context of a comparative, prospective life-cycle analysis framework. Three R and D options using nc-Si bottom layer were evaluated and compared to the current triple-junction a-Si design, i.e., a-Si/a-SiGe/a-SiGe. The life-cycle energy demand to deposit nc-Si was estimated from parametric analyses of film thickness, deposition rate, precursor gas usage, and power for generating gas plasma. We found that extended deposition time and increased gas usages associated to the relatively high thickness of nc-Si lead to a larger primary energy demand for the nc-Si bottom layer designs, than the current triple-junction a-Si. Assuming an 8% conversion efficiency, the energy payback time of those R and D designs will be 0.7-0.9 years, close to that of currently commercial triple-junction a-Si design, 0.8 years. Future scenario analyses show that if nc-Si film is deposited at a higher rate (i.e., 2-3 nm/s), and at the same time the conversion efficiency reaches 10%, the energy-payback time could drop by 30%.

  5. Valence electronenergy-lossspectroscopystudyofZrSiO4 and ZrO2...

    Office of Scientific and Technical Information (OSTI)

    electronenergy-lossspectroscopystudyofZrSiO4 and ZrO2 ZrSiO4 (zircon) and m-ZrO2 (zirconia) are fundamental and industrially important materials.This work reports the detailed...

  6. Fuel Consumption and NOx Trade-offs on a Port-Fuel-Injected SI...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    NOx Trade-offs on a Port-Fuel-Injected SI Gasoline Engine Equipped with a Lean-NOx Trap Fuel Consumption and NOx Trade-offs on a Port-Fuel-Injected SI Gasoline Engine Equipped with ...

  7. Direct Visualization of Spray and Combustion Inside a DI-SI Engine...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Visualization of Spray and Combustion Inside a DI-SI Engine and Its Implications to Flex-Fuel VVT Operations Direct Visualization of Spray and Combustion Inside a DI-SI Engine and ...

  8. PID Failure of c-Si and Thin-Film Modules and Possible Correlation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    PID Failure of c-Si and Thin-Film Modules and Possible Correlation with Leakage Currents PID Failure of c-Si and Thin-Film Modules and Possible Correlation with Leakage Currents ...

  9. Sensitivities of I-V Parameters in C-Si PV Modules of Hygrothermal...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Sensitivities of I-V Parameters in C-Si PV Modules of Hygrothermal Stress Sensitivities of I-V Parameters in C-Si PV Modules of Hygrothermal Stress Presented at the PV Module ...

  10. Phase relations in the Fe-FeSi system at high pressures and temperatur...

    Office of Scientific and Technical Information (OSTI)

    We determined melting temperatures and subsolidus phase relations of Fe-9 wt% Si and ... We find the B2 crystal structure in Fe-9Si where previous studies reported the less ...

  11. Microstructural Contol of the Porous Si3N4 Ceramics Consisted...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Contol of the Porous Si3N4 Ceramics Consisted of 3-Dimensionally Intermingled Rod-like Grains Microstructural Contol of the Porous Si3N4 Ceramics Consisted of 3-Dimensionally...

  12. Chemical reactivity of CVC and CVD SiC with UO2 at high temperatures

    SciTech Connect (OSTI)

    Silva, Chinthaka M; Katoh, Yutai; Voit, Stewart L; Snead, Lance Lewis

    2015-01-01

    Two types of silicon carbide (SiC) synthesized using two different vapor deposition processes were embedded in UO2 pellets and evaluated for their potential chemical reaction with UO2. While minor reactivity between chemical-vapor-composited (CVC) SiC and UO2 was observed at comparatively low temperatures of 1100 and 1300 C, chemical-vapor-deposited (CVD) SiC did not show any such reactivity, according to microstructural investigations. However, both CVD and CVC SiCs showed some reaction with UO2 at a higher temperature (1500 C). Elemental maps supported by phase maps obtained using electron backscatter diffraction indicated that CVC SiC was more reactive than CVD SiC at 1500 C. Furthermore, this investigation indicated the formation of uranium carbides and uranium silicide chemical phases such as UC, USi2, and U3Si2 as a result of SiC reaction with UO2.

  13. Optical characterizations of doped silicon nanocrystals grown by co-implantation of Si and dopants in SiO₂

    SciTech Connect (OSTI)

    Frégnaux, M.; Khelifi, R.; Muller, D.; Mathiot, D.

    2014-10-14

    Co-implantation, with overlapping implantation projected ranges, of Si and doping species (P, As, and B) followed by a thermal annealing step is a viable route to form doped Si nanocrystals (NCs) embedded in silica (SiO₂). In this paper, we investigate optical characterizations of both doped and un-doped Si-NCs prepared by this method. The effective NC presence in the oxide layer and their crystallinity is verified by Raman spectrometry. Photoluminescence (PL) and PL excitation measurements reveal quantum confinement effects and a gradual PL quenching with increasing dopant concentrations. In un-doped NC, the measured Stokes shift remains constant and its value ~0.2 eV is almost twice the Si–O vibration energy. This suggests that a possible radiative recombination path is a fundamental transition assisted by a local phonon. PL lifetime investigations show that PL time-decays follow a stretched exponential. Using a statistical model for luminescence quenching, a typical NC diameter close to 2 nm is obtained for As- and P-doped samples, consistent with our previous atomic probe tomography (APT) analyses. APT also demonstrated that n-type dopant (P and As) are efficiently introduced in the NC core, whereas p-type dopant (B) are located at the NC/SiO₂ interface. This last observation could explain the failure of the luminescence-quenching model to determine NC size in B-doped samples. All together, these experimental observations question on possible different carrier recombination paths in P or As doped NC compared to B one's.

  14. Development of Si-based High Capacity Anodes | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Si-based High Capacity Anodes Development of Si-based High Capacity Anodes 2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting PDF icon es144_zhang_2012_p.pdf More Documents & Publications Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes and Functional Polymer Binders Development of Si-based High Capacity Anodes Vehicle Technologies Office Merit Review 2014: Synthesis and Characterization of

  15. Low Cost SiOx-Graphite and High Voltage Spinel Cathode | Department of

    Office of Environmental Management (EM)

    Energy Low Cost SiOx-Graphite and High Voltage Spinel Cathode Low Cost SiOx-Graphite and High Voltage Spinel Cathode 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation PDF icon es048_zaghib_2011_o.pdf More Documents & Publications Low Cost SiOx-Graphite and Olivine Materials Low Cost SiOx-Graphite and Olivine Materials BATT Program- Summary and Future Plans

  16. Modeling and Testing Miniature Torsion Specimens for SiC Joining Development Studies for Fusion

    SciTech Connect (OSTI)

    Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.; Roosendaal, Timothy J.; Borlaug, Brennan A.; Ferraris, Monica; Ventrella, Andrea; Katoh, Yutai

    2015-08-19

    The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. Miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti3SiC2 + SiC joints with CVD-SiC and tested in torsion-shear prior to and after neutron irradiation. However, many of these miniature torsion specimens fail out-of-plane within the CVD-SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated joint strengths to determine the effects of the irradiation. Finite element elastic damage and elastic-plastic damage models of miniature torsion joints are developed that indicate shear fracture is likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated joint test data for a variety of joint materials. The unirradiated data includes Ti3SiC2 + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. The implications for joint data based on this sample design are discussed.

  17. Near-infrared light absorption by polycrystalline SiSn alloys grown on insulating layers

    SciTech Connect (OSTI)

    Kurosawa, Masashi; Kato, Motohiro; Yamaha, Takashi; Taoka, Noriyuki; Nakatsuka, Osamu; Zaima, Shigeaki

    2015-04-27

    High-Sn-content SiSn alloys are strongly desired for the next-generation near-infrared optoelectronics. A polycrystalline growth study has been conducted on amorphous SiSn layers with a Sn-content of 2%30% deposited on either a substrate of SiO{sub 2} or SiN. Incorporating 30% Sn into Si permits the crystallization of the amorphous layers at annealing temperatures below the melting point of Sn (231.9?C). Composition analyses indicate that approximately 20% of the Sn atoms are substituted into the Si lattice after solid-phase crystallization at 150220?C for 5?h. Correspondingly, the optical absorption edge is red-shifted from 1.12?eV (Si) to 0.83?eV (Si{sub 1?x}Sn{sub x} (x???0.18??0.04)), and the difference between the indirect and direct band gap is significantly reduced from 3.1?eV (Si) to 0.22?eV (Si{sub 1?x}Sn{sub x} (x???0.18??0.04)). These results suggest that with higher substitutional Sn content the SiSn alloys could become a direct band-gap material, which would provide benefits for Si photonics.

  18. Forsterite film formation and grain growth in 3% Si steel

    SciTech Connect (OSTI)

    Cunha, M.A.; Cesar, M.G.M.M. )

    1994-11-01

    The forsterite film in 3% Si steel is formed by a solid state reaction of the annealing separator, MgO, with SiO[sub 2] that results from the reduction of the fayalite layer in the hydrogen atmosphere in the high temperature anneal. In this work, secondary recrystallization was about complete at 1,000 C. After that temperature tertiary recrystallization can occur if the boundary drag of the second phase particles can be overcome. Addition of phosphates to the annealing separator affects the morphology of the forsterite film and can have an important effect on tertiary recrystallization by affecting the rate of decrease of the boundary-drag and/or the surface energy relationship.

  19. On the state of Mn impurity implanted in Si

    SciTech Connect (OSTI)

    Orlov, A. F.; Bublik, V. T.; Vdovin, V. I.; Agafonov, Yu. A.; Balagurov, L. A.; Zinenko, V. I.; Kulemanov, I. V.; Shcherbachev, K. D.

    2009-07-15

    The state of manganese impurity in implanted silicon at implantation doses of up to 5 x 10{sup 16} cm{sup -2} has been investigated by X-ray diffraction and transmission electron microscopy. It is established that, after short-term vacuum annealing at 850{sup o}C, most of the implanted manganese impurities are in microinclusions up to 20 nm in size formed by a tetragonal silicide phase of the Mn{sub 15}Si{sub 26} type.

  20. Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Functional Polymer Binders | Department of Energy 2 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting PDF icon es147_wang_2012_p.pdf More Documents & Publications Novel Lithium Ion Anode Structures: Overview of New DOE BATT Anode Projects Synthesis and Characterization of Structured Si-Carbon Nanocomposite Anodes and Functional Polymer Binders Development of High Capacity Anode for Li-ion Batteries

  1. SiO{sub 2}/SiC structures annealed in D{sub 2}{sup 18}O: Compositional and electrical effects

    SciTech Connect (OSTI)

    Pitthan, E. Corra, S. A.; Soares, G. V.; Boudinov, H. I.; Stedile, F. C.

    2014-03-17

    Effects of water vapor annealing on SiO{sub 2}/4H-SiC structures formed following different routes were investigated using water isotopically enriched in {sup 18}O and {sup 2}H (D). Isotopic exchange between oxygen from the water vapor and oxygen from SiO{sub 2} films deposited on 4H-SiC was observed in the whole depth of the films, differently from the behavior of SiO{sub 2} films thermally grown on 4H-SiC. The highest amount of D was obtained in the sample with the highest negative fixed charge concentration, suggesting that the D incorporation occurs in defects in the structure that exist prior to the annealing. As a consequence of the water annealing, a significant reduction in the negative effective charge in metal-oxide-semiconductor capacitors and the removal of the SiO{sub 2}/SiC interfacial region was observed, attributed to the reduction of the amount of SiO{sub x}C{sub y} compounds in the interfacial region.

  2. Fe-implanted 6H-SiC: Direct evidence of Fe{sub 3}Si nanoparticles observed by atom probe tomography and {sup 57}Fe Mssbauer spectroscopy

    SciTech Connect (OSTI)

    Diallo, M. L.; Fnidiki, A. Lard, R.; Cuvilly, F.; Blum, I.; Lechevallier, L.; Debelle, A.; Thom, L.; Viret, M.; Marteau, M.; Eyidi, D.; Declmy, A.

    2015-05-14

    In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, {sup 57}Fe Mssbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe{sub 3}Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

  3. Scale Up of Si/Si0.8GE0.2 and B4C/B9C Superlattices for Harvesting of Waste

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Heat in Diesel Engines | Department of Energy Scale Up of Si/Si0.8GE0.2 and B4C/B9C Superlattices for Harvesting of Waste Heat in Diesel Engines Scale Up of Si/Si0.8GE0.2 and B4C/B9C Superlattices for Harvesting of Waste Heat in Diesel Engines 2003 DEER Conference Presentation: Pacific Northwest National Laboratory PDF icon 2003_deer_martin.pdf More Documents & Publications Quantum Well Thermoelectrics and Waste Heat Recovery Multilayer Thin-Film Thermoelectric Materials for Vehicle

  4. Electronic properties of III-nitride semiconductors: A first-principles investigation using the Tran-Blaha modified Becke-Johnson potential

    SciTech Connect (OSTI)

    Araujo, Rafael B. Almeida, J. S. de Ferreira da Silva, A.

    2013-11-14

    In this work, we use density functional theory to investigate the influence of semilocal exchange and correlation effects on the electronic properties of III-nitride semiconductors considering zinc-blende and wurtzite crystal structures. We find that the inclusion of such effects through the use of the Tran-Blaha modified Becke-Johnson potential yields an excellent description of the electronic structures of these materials giving energy band gaps which are systematically larger than the ones obtained with standard functionals such as the generalized gradient approximation. The discrepancy between the experimental and theoretical band gaps is then significantly reduced with semilocal exchange and correlation effects. However, the effective masses are overestimated in the zinc-blende nitrides, but no systematic trend is found in the wurtzite compounds. New results for energy band gaps and effective masses of zinc-blende and wurtzite indium nitrides are presented.

  5. Dy-Mn-Si as a representative of family of 'Dy-Transition

    Office of Scientific and Technical Information (OSTI)

    Metal-Si' systems: Its isothermal sections, empirical rProd. Type: FTPules and new rare-earth manganese silicides (Journal Article) | SciTech Connect Dy-Mn-Si as a representative of family of 'Dy-Transition Metal-Si' systems: Its isothermal sections, empirical rProd. Type: FTPules and new rare-earth manganese silicides Citation Details In-Document Search Title: Dy-Mn-Si as a representative of family of 'Dy-Transition Metal-Si' systems: Its isothermal sections, empirical rProd. Type: FTPules

  6. High quality SiC microdisk resonators fabricated from monolithic epilayer wafers

    SciTech Connect (OSTI)

    Magyar, Andrew P.; Bracher, David; Lee, Jonathan C.; Hu, Evelyn L.; Aharonovich, Igor

    2014-02-03

    The exquisite mechanical properties of SiC have made it an important industrial material with applications in microelectromechanical devices and high power electronics. Recently, the optical properties of SiC have garnered attention for applications in photonics, quantum information, and spintronics. This work demonstrates the fabrication of microdisks formed from a p-N SiC epilayer material. The microdisk cavities fabricated from the SiC epilayer material exhibit quality factors of as high as 9200 and the approach is easily adaptable to the fabrication of SiC-based photonic crystals and other photonic and optomechanical devices.

  7. Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

    SciTech Connect (OSTI)

    Ciurea, Magdalena Lidia Lazanu, Sorina

    2014-10-06

    Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increase of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.

  8. Ion beam synthesis of SiGe alloy layers

    SciTech Connect (OSTI)

    Im, Seongil

    1994-05-01

    Procedures required for minimizing structural defects generated during ion beam synthesis of SiGe alloy layers were studied. Synthesis of 200 mm SiGe alloy layers by implantation of 120-keV Ge ions into <100> oriented Si wafers yielded various Ge peak concentrations after the following doses, 2{times}10{sup 16}cm{sup {minus}2}, 3{times}10{sup 16}cm{sup {minus}2} (mid), and 5{times}10{sup 16}cm{sup {minus}2} (high). Following implantation, solid phase epitaxial (SPE) annealing in ambient N2 at 800C for 1 hr. resulted in only slight redistribution of the Ge. Two kinds of extended defects were observed in alloy layers over 3{times}l0{sup 16}cm{sup {minus}2}cm dose at room temperature (RT): end-of-range (EOR) dislocation loops and strain-induced stacking faults. Density of EOR dislocation loops was much lower in alloys produced by 77K implantation than by RT implantation. Decreasing the dose to obtain 5 at% peak Ge concentration prevents strain relaxation, while those SPE layers with more than 7 at% Ge peak show high densities of misfit- induced stacking faults. Sequential implantation of C following high dose Ge implantation (12 at% Ge peak concentration in layer) brought about a remarkable decrease in density of misfit-induced stacking faults. For peak implanted C > 0.55 at%, stacking fault generation in the epitaxial layer was suppressed, owing to strain compensation by C atoms in the SiGe lattice. A SiGe alloy layer with 0.9 at% C peak concentration under a 12 at% Ge peak exhibited the best microstructure. Results indicate that optimum Ge/C ratio for strain compensation is between 11 and 22. The interface between amorphous and regrown phases (a/c interface) had a dramatic morphology change during its migration to the surface. Initial <100> planar interface decomposes into a <111> faceted interface, changing the growth kinetics; this is associated with strain relaxation by stacking fault formation on (111) planes in the a/c interface.

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

    SciTech Connect (OSTI)

    Xie, Min; Li, Dongsheng; Chen, Le; Wang, Feng; Zhu, Xiaodong; Yang, Deren

    2013-03-25

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

  10. Si Passivation and Chemical Vapor Deposition of Silicon Nitride: Final Technical Report, March 18, 2007

    SciTech Connect (OSTI)

    Atwater, H. A.

    2007-11-01

    This report investigated chemical and physical methods for Si surface passivation for application in crystalline Si and thin Si film photovoltaic devices. Overall, our efforts during the project were focused in three areas: i) synthesis of silicon nitride thin films with high hydrogen content by hot-wire chemical vapor deposition; ii) investigation of the role of hydrogen passivation of defects in crystalline Si and Si solar cells by out diffusion from hydrogenated silicon nitride films; iii) investigation of the growth kinetics and passivation of hydrogenated polycrystalline. Silicon nitride films were grown by hot-wire chemical vapor deposition and film properties have been characterized as a function of SiH4/NH3 flow ratio. It was demonstrated that hot-wire chemical vapor deposition leads to growth of SiNx films with controllable stoichiometry and hydrogen.

  11. Development of ASTM Standard for SiC-SiC Joint Testing Final Scientific/Technical Report

    SciTech Connect (OSTI)

    Jacobsen, George; Back, Christina

    2015-10-30

    As the nuclear industry moves to advanced ceramic based materials for cladding and core structural materials for a variety of advanced reactors, new standards and test methods are required for material development and licensing purposes. For example, General Atomics (GA) is actively developing silicon carbide (SiC) based composite cladding (SiC-SiC) for its Energy Multiplier Module (EM2), a high efficiency gas cooled fast reactor. Through DOE funding via the advanced reactor concept program, GA developed a new test method for the nominal joint strength of an endplug sealed to advanced ceramic tubes, Fig. 1-1, at ambient and elevated temperatures called the endplug pushout (EPPO) test. This test utilizes widely available universal mechanical testers coupled with clam shell heaters, and specimen size is relatively small, making it a viable post irradiation test method. The culmination of this effort was a draft of an ASTM test standard that will be submitted for approval to the ASTM C28 ceramic committee. Once the standard has been vetted by the ceramics test community, an industry wide standard methodology to test joined tubular ceramic components will be available for the entire nuclear materials community.

  12. SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE

    SciTech Connect (OSTI)

    Xu, Yuchen; Zinner, Ernst; Gallino, Roberto; Heger, Alexander; Pignatari, Marco; Lin, Yangting

    2015-02-01

    We report C, Si, N, S, Mg-Al, and Ca-Ti isotopic compositions of presolar silicon carbide (SiC) grains from the SiC-rich KJE size fraction (0.5-0.8 μm) of the Murchison meteorite. One thousand one hundred thirteen SiC grains were identified based on their C and Si isotopic ratios. Mainstream, AB, C, X, Y, and Z subtypes of SiC, and X-type silicon nitride (Si{sub 3}N{sub 4}) account for 81.4%, 5.7%, 0.1%, 1.5%, 5.8%, 4.9%, and 0.4%, respectively. Twenty-five grains with unusual Si isotopic ratios, including one C grain, 16 X grains, 1 Y grain, 5 Z grains, and 2 X-type Si{sub 3}N{sub 4} grains were selected for N, S, Mg-Al, and Ca-Ti isotopic analysis. The C grain is highly enriched in {sup 29}Si and {sup 30}Si (δ{sup 29}Si = 1345‰ ± 19‰, δ{sup 30}Si = 1272‰ ± 19‰). It has a huge {sup 32}S excess, larger than any seen before, and larger than that predicted for the Si/S supernova (SN) zone, providing evidence against the elemental fractionation model by Hoppe et al. Two SN models investigated here present a more satisfying explanation in terms of a radiogenic origin of {sup 32}S from the decay of short-lived {sup 32}Si (τ{sub 1/2} = 153 yr). Silicon-32 as well as {sup 29}Si and {sup 30}Si can be produced in SNe by short neutron bursts; evidence for initial {sup 44}Ti (τ{sub 1/2} = 60 yr) in the C grain is additional evidence for an SN origin. The X grains have marginal {sup 32}S excesses, much smaller than expected from their large {sup 28}Si excesses. Similarly, the Y and Z grains do not show the S-isotopic anomalies expected from their large Si isotopic anomalies. Low intrinsic S contents and contamination with isotopically normal S are the most likely explanations.

  13. Top-emission Si-based phosphor organic light emitting diode with Au doped ultrathin n-Si film anode and bottom Al mirror

    SciTech Connect (OSTI)

    Li, Y. Z.; Xu, W. J.; Ran, G. Z. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Qin, G. G. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Key Lab of Semiconductor Materials, CAS, Beijing 100083 (China)

    2009-07-20

    We report a highly efficient top-emission Si-based phosphor organic light emitting diode (PhOLED) with an ultrathin polycrystalline n-Si:Au film anode and a bottom Al mirror. This anode is formed by magnetron sputtering followed by Ni induced crystallization and then Au diffusion. By optimizing the thickness of the n-Si:Au film anode, the Au diffusion temperature, and the other parameters of the PhOLED, the highest current and power efficiencies of the n-Si:Au film anode PhOLED reached 85{+-}9 cd/A and 80{+-}8 lm/W, respectively, corresponding to an external quantum efficiency of 21{+-}2% and a power conversion efficiency of 15{+-}2%, respectively, which are about 60% and 110% higher than those of the indium tin oxide anode counterpart and 70% and 50% higher than those of the bulk n{sup +}-Si:Au anode counterpart, respectively.

  14. Porous SiC nanowire arrays as stable photocatalyst for water splitting under UV irradiation

    SciTech Connect (OSTI)

    Liu, Hailong; She, Guangwei; Mu, Lixuan; Shi, Wensheng

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Arrays of porous SiC nanowires prepared by a facile in situ carbonizing method. Black-Right-Pointing-Pointer Utilizing the SiC nanowire arrays as photocatalysis for water splitting. Black-Right-Pointing-Pointer Excellent photocatalytic performance under the UV irradiation. Black-Right-Pointing-Pointer Very high stability of the SiC nanowire photocatalyst. -- Abstract: In this study, we report the fabrication and photocatalytic properties of the oriented arrays of SiC nanowires on the Si substrate. The SiC nanowire arrays were prepared by carbonizing the Si nanowire arrays with the graphite powder at 1250 Degree-Sign C. The as-prepared SiC nanowires are highly porous, which endows them with a high surface-to-volume ratio. Considering the large surface areas and the high stability, the porous SiC nanowire arrays were used as photocatalyst for water splitting under UV irradiation. It was found that such porous SiC structure exhibited an enhanced and extremely stable photocatalytic performance.

  15. Light absorption and electrical transport in Si:O alloys for photovoltaics

    SciTech Connect (OSTI)

    Mirabella, S.; Crupi, I.; Miritello, M.; Simone, F.; Di Martino, G.; Di Stefano, M. A.; Di Marco, S.; Priolo, F.

    2010-11-15

    Thin films (100-500 nm) of the Si:O alloy have been systematically characterized in the optical absorption and electrical transport behavior, by varying the Si content from 43 up to 100 at. %. Magnetron sputtering or plasma enhanced chemical vapor deposition have been used for the Si:O alloy deposition, followed by annealing up to 1250 deg. C. Boron implantation (30 keV, 3-30x10{sup 14} B/cm{sup 2}) on selected samples was performed to vary the electrical sheet resistance measured by the four-point collinear probe method. Transmittance and reflectance spectra have been extracted and combined to estimate the absorption spectra and the optical band gap, by means of the Tauc analysis. Raman spectroscopy was also employed to follow the amorphous-crystalline (a-c) transition of the Si domains contained in the Si:O films. The optical absorption and the electrical transport of Si:O films can be continuously and independently modulated by acting on different parameters. The light absorption increases (by one decade) with the Si content in the 43-100 at. % range, determining an optical band gap which can be continuously modulated into the 2.6-1.6 eV range, respectively. The a-c phase transition in Si:O films, causing a significant reduction in the absorption coefficient, occurs at increasing temperatures (from 600 to 1100 deg. C) as the Si content decreases. The electrical resistivity of Si:O films can be varied among five decades, being essentially dominated by the number of Si grains and by the doping. Si:O alloys with Si content in the 60-90 at. % range (named oxygen rich silicon films), are proved to join an appealing optical gap with a viable conductivity, being a good candidate for increasing the conversion efficiency of thin-film photovoltaic cell.

  16. Diamond turning of Si and Ge single crystals

    SciTech Connect (OSTI)

    Blake, P.; Scattergood, R.O.

    1988-12-01

    Single-point diamond turning studies have been completed on Si and Ge crystals. A new process model was developed for diamond turning which is based on a critical depth of cut for plastic flow-to-brittle fracture transitions. This concept, when combined with the actual machining geometry for single-point turning, predicts that {open_quotes}ductile{close_quotes} machining is a combined action of plasticity and fracture. Interrupted cutting experiments also provide a meant to directly measure the critical depth parameter for given machining conditions.

  17. Application of RTG (SiGe) technology to MESUR

    SciTech Connect (OSTI)

    Vicente, F.A. )

    1993-01-15

    This paper discusses providing electrical power for the Mars Environmental Survey (MESUR) mission. The use of radioisotope thermoelectric generator (RTG) technology using SiGe enables total satisfaction of the mission requirements. This technology permits placing the survey landers at any location on Mars, with the capability of transmitting data directly to Earth. If a relay satellite is deployed, the modular construction of the RTG permits tailoring the power to match that mission configuration. Presented are various configurations and trades directed toward achieving operational status, first with a pathfinder'' mission and subsequently with the full complement of landers.

  18. Single-mode deformation via nanoindentation in dc-Si

    SciTech Connect (OSTI)

    Wong, Sherman; Haberl, Bianca; Williams, James S.; Bradby, Jodie E.

    2015-01-01

    The mixture of the metastable body-centered cubic (bc8) and rhombohedral (r8) phases of silicon that is formed via nanoindentation of diamond cubic (dc) silicon exhibits properties that are of scientifc and technological interest. This letter demonstrates that large regions of this mixed phase can be formed in crystalline Si via nanoindentation without signifcant damage to the surrounding crystal. Cross-sectional transmission electron microscopy is used to show that volumes 6 um wide and up to 650 nm deep can be generated in this way using a spherical tip of 21.5 um diameter. The phase transformed region is characterised using both Raman microspectroscopy and transmission electron microscopy. It is found that uniform loading using large spherical indenters can favor phase transformation as the sole deformation mechanism as long as the maximum load is below a critical level. We suggest that the sluggish nature of the transformation from the dc-Si phase to the metallic (b-Sn) phase normally results in competing deformation mechanisms such as slip and cracking but these can be suppressed by controlled loading conditions.

  19. Microstructural Development in Al-Si Powder During Rapid Solidification

    SciTech Connect (OSTI)

    Amber Lynn Genau

    2004-12-19

    Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to further exploit the potential of rapid solidification processing. Aluminum-silicon, an alloy of significant industrial importance, was chosen as a model for simple eutectic systems displaying an unfaceted/faceted interface and skewed coupled eutectic growth zone, Al-Si powder produced by high pressure gas atomization was studied to determine the relationship between microstructure and alloy composition as a function of powder size and atomization gas. Critical experimental measurements of hypereutectic (Si-rich) compositions were used to determine undercooling and interface velocity, based on the theoretical models which are available. Solidification conditions were analyzed as a function of particle diameter and distance from nucleation site. A revised microstructural map is proposed which allows the prediction of particle morphology based on temperature and composition. It is hoped that this work, by providing enhanced understanding of the processes which govern the development of the solidification morphology of gas atomized powder, will eventually allow for better control of processing conditions so that particle microstructures can be optimized for specific applications.

  20. Method of using a germanium layer transfer to Si for photovoltaic applications and heterostructure made thereby

    DOE Patents [OSTI]

    Atwater, Jr., Harry A.; Zahler, James M.

    2006-11-28

    Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.

  1. Light Trapping for High Efficiency Heterojunction Crystalline Si Solar Cells: Preprint

    SciTech Connect (OSTI)

    Wang, Q.; Xu, Y.; Iwaniczko, E.; Page, M.

    2011-04-01

    Light trapping plays an important role to achieve high short circuit current density (Jsc) and high efficiency for amorphous/crystalline Si heterojunction solar cells. Si heterojunction uses hydrogenated amorphous Si for emitter and back contact. This structure of solar cell posses highest open circuit voltage of 0.747 V at one sun for c-Si based solar cells. It also suggests that over 25% record-high efficiency is possible with further improvement of Jsc. Light trapping has two important tasks. The first one is to reduce the surface reflectance of light to zero for the solar spectrum that Si has a response. The second one is to increase the effective absorption length to capture all the photon. For Si heterojunction solar cell, surface texturing, anti-reflectance indium tin oxides (ITO) layer at the front and back are the key area to improve the light trapping.

  2. Oxidation of SiC cladding under Loss of Coolant Accident (LOCA) conditions in LWRs

    SciTech Connect (OSTI)

    Lee, Y.; Yue, C.; Arnold, R. P.; McKrell, T. J.; Kazimi, M. S. [Dept. of Nuclear Science and Engineering, Massachusetts Inst. of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States)

    2012-07-01

    An experimental assessment of Silicon Carbide (SiC) cladding oxidation rate in steam under conditions representative of Loss of Coolant Accidents (LOCA) in light water reactors (LWRs) was conducted. SiC oxidation tests were performed with monolithic alpha phase tubular samples in a vertical quartz tube at a steam temperature of 1140 deg. C and steam velocity range of 1 to 10 m/sec, at atmospheric pressure. Linear weight loss of SiC samples due to boundary layer controlled reaction of silica scale (SiO{sub 2} volatilization) was experimentally observed. The weight loss rate increased with increasing steam flow rate. Over the range of test conditions, SiC oxidation rates were shown to be about 3 orders of magnitude lower than the oxidation rates of zircaloy 4. A SiC volatilization correlation for developing laminar flow in a vertical channel is formulated. (authors)

  3. The reliability studies of nano-engineered SiGe HBTs using Pelletron accelerator

    SciTech Connect (OSTI)

    Prakash, A. P. Gnana Praveen, K. C.; Pushpa, N.; Cressler, John D.

    2015-05-15

    The effects of high energy ions on the electrical characteristics of silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were studied in the total dose of ranging from 600 krad to 100 Mrad (Si). The two generations (50 GHz and 200 GHz) of SiGe HBTs were exposed to 50 MeV lithium, 75 MeV boron and 100 MeV oxygen ions. The electrical characteristics of SiGe HBTs were studied before and after irradiation. The SiGe HBTs were exposed to {sup 60}Co gamma radiation in the same total dose. The results are systematically compared in order to understand the interaction of ions and ionizing radiation with SiGe HBTs.

  4. Annealed Si/SiGeC Superlattices Studied by Dark-Field Electron Holography, ToF-SIMS and Infrared Spectroscopy

    SciTech Connect (OSTI)

    Denneulin, T.; Py, M.; Barnes, J. P.; Rochat, N.; Hartmann, J. M.; Cooper, D.; Rouviere, J. L.

    2011-11-10

    Si/SiGeC superlattices are used in the construction of new generation devices such as multichannel transistors. The incorporation of C in the SiGe layers allows for a better control of the strain and the Ge content. However the formation of {beta}-SiC clusters during annealing at high temperature limits the thermal stability of the alloy. It leads to a strong modification of the strain due to the reduction of the substitutional carbon content. Here, we investigated the behavior of Si/SiGeC superlattices that have been annealed using different characterization techniques: dark-field electron holography for the evaluation of strain; infrared spectroscopy and ToF-SIMS for the determination of the composition. It was found that after annealing at 1050 deg. C, the reduction of the substitutional C proportion leads to a recovery of the perpendicular strain in the superlattice. It was also proposed that the local arrangement of C atoms in a third nearest neighbor configuration is an intermediary step during the formation of the SiC clusters.

  5. Arrays of SiO(2) Substrate-Free Micromechanical Uncooled THz and Infrared

    Office of Scientific and Technical Information (OSTI)

    Detectors (Journal Article) | SciTech Connect Journal Article: Arrays of SiO(2) Substrate-Free Micromechanical Uncooled THz and Infrared Detectors Citation Details In-Document Search Title: Arrays of SiO(2) Substrate-Free Micromechanical Uncooled THz and Infrared Detectors We describe the design, fabrication, and characterization of arrays of uncooled infrared and terahertz micromechanical detectors that utilize SiO2 as a main structural material. Materials with highly dissimilar

  6. Chemical Bonding In Amorphous Si Coated-carbon Nanotube As Anodes...

    Office of Scientific and Technical Information (OSTI)

    Title: Chemical Bonding In Amorphous Si Coated-carbon Nanotube As Anodes For Li ion Batteries: A XANES Study The chemical bonding nature and its evolution upon electrochemical ...

  7. A New SiC-based DPF for the Automotive Industry | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    A New SiC-based DPF for the Automotive Industry A New SiC-based DPF for the Automotive Industry Evaluation and example of performance of a new SiC-based diesel particulate filter made using unique industrial sintering process. PDF icon deer08_tsuneyoshi.pdf More Documents & Publications Diesel Particulate Filters: Market Introducution in Europe Hot Gas Filtration of Fine and Ultra fine Particles with Liquid Phase Sintered SiC Ceramic DPF Development of Acicular Mullite Materials for Diesel

  8. The thermal equation of state of (Mg, Fe)SiO[subscript 3] bridgmanite...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: The thermal equation of state of (Mg, Fe)SiOsubscript 3 bridgmanite (perovskite) and implications for lower mantle structures ...

  9. Balance of optical, structural, and electrical properties of textured liquid phase crystallized Si solar cells

    SciTech Connect (OSTI)

    Preidel, V. Amkreutz, D.; Haschke, J.; Wollgarten, M.; Rech, B.; Becker, C.

    2015-06-14

    Liquid phase crystallized Si thin-film solar cells on nanoimprint textured glass substrates exhibiting two characteristic, but distinct different surface structures are presented. The impact of the substrate texture on light absorption, the structural Si material properties, and the resulting solar cell performance is analyzed. A pronounced periodic substrate texture with a vertical feature size of about 1 μm enables excellent light scattering and light trapping. However, it also gives rise to an enhanced Si crystal defect formation deteriorating the solar cell performance. In contrast, a random pattern with a low surface roughness of 45 nm allows for the growth of Si thin films being comparable to Si layers on planar reference substrates. Amorphous Si/crystalline Si heterojunction solar cells fabricated on the low-roughness texture exhibit a maximum open circuit voltage of 616 mV and internal quantum efficiency peak values exceeding 90%, resulting in an efficiency potential of 13.2%. This demonstrates that high quality crystalline Si thin films can be realized on nanoimprint patterned glass substrates by liquid phase crystallization inspiring the implementation of tailor-made nanophotonic light harvesting concepts into future liquid phase crystallized Si thin film solar cells on glass.

  10. Direct thermal-neutron capture by {sup 30}Si (Journal Article) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Direct thermal-neutron capture by {sup 30}Si Citation Details In-Document Search Title: Direct thermal-neutron capture by {sup 30}Si Five primary electric-dipole transitions in {sup 31}Si account for the bulk ({approx}98%) of the total thermal-neutron capture cross section (107{+-}3 mb) of {sup 30}Si. We have recalculated the partial cross sections for these transitions using direct-capture theory and reliable spectroscopic factors for the (d,p) reaction, which have become available

  11. Effect of high temperature deposition on CoSi{sub 2} phase formation

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Effect of high temperature deposition on CoSi{sub 2} phase formation Citation Details In-Document Search Title: Effect of high temperature deposition on CoSi{sub 2} phase formation This paper discusses the nucleation behaviour of the CoSi to CoSi{sub 2} transformation from cobalt silicide thin films grown by deposition at elevated substrate temperatures ranging from 375 Degree-Sign C to 600 Degree-Sign C. A combination of channelling, real-time Rutherford

  12. Chemical Bonding In Amorphous Si Coated-carbon Nanotube As Anodes For Li

    Office of Scientific and Technical Information (OSTI)

    ion Batteries: A XANES Study (Journal Article) | SciTech Connect Chemical Bonding In Amorphous Si Coated-carbon Nanotube As Anodes For Li ion Batteries: A XANES Study Citation Details In-Document Search Title: Chemical Bonding In Amorphous Si Coated-carbon Nanotube As Anodes For Li ion Batteries: A XANES Study The chemical bonding nature and its evolution upon electrochemical cycling in amorphous Si coated-carbon nanotube (Si-CNT) anode has been investigated using comprehensive X-ray

  13. Sandia Energy - Sandia, DOE Energy Storage Program, GeneSiCSemiconduc...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    DOE Energy Storage Program, GeneSiC Semiconductor, U.S. Army ARDEC: Ultra-High-Voltage Silicon Carbide Thyristors Home Infrastructure Security Energy Grid Integration Partnership...

  14. Identification of luminescent surface defect in SiC quantum dots

    SciTech Connect (OSTI)

    Dai, Dejian; Guo, Xiaoxiao; Fan, Jiyang

    2015-02-02

    The surface defect that results in the usually observed blue luminescence in the SiC quantum dots (QDs) remains unclear. We experimentally identify that the surface defect C=O (in COO) is responsible for this constant blue luminescence. The HOC=O [n{sub (OH)} ? ?*{sub (CO)}] interaction between the hydroxyl and carbonyl groups changes the energy levels of C=O and makes the light absorption/emission arise at around 326/438?nm. Another surface defect (SiSi) is identified and its light absorption contributes to both C=O-related luminescence and quantum-confinement luminescence of the SiC QDs.

  15. White-blue electroluminescence from a Si quantum dot hybrid light-emitting diode

    SciTech Connect (OSTI)

    Xin, Yunzi; Nishio, Kazuyuki; Saitow, Ken-ichi

    2015-05-18

    A silicon (Si) quantum dot (QD)-based hybrid inorganic/organic light-emitting diode (LED) was fabricated via solution processing. This device exhibited white-blue electroluminescence at a low applied voltage of 6?V, with 78% of the effective emission obtained from the Si QDs. This hybrid LED produced current and optical power densities 280 and 350 times greater than those previously reported for such device. The superior performance of this hybrid device was obtained by both the prepared Si QDs and the optimized layer structure and thereby improving carrier migration through the hybrid LED and carrier recombination in the homogeneous Si QD layer.

  16. Theoretical investigations of defects in a Si-based digital ferromagne...

    Office of Scientific and Technical Information (OSTI)

    Theoretical investigations of defects in a Si-based digital ferromagnetic heterostructure - a spintronic material Citation Details In-Document Search Title: Theoretical...

  17. Porous Si spheres encapsulated in carbon shells with enhanced anodic performance in lithium-ion batteries

    SciTech Connect (OSTI)

    Wang, Hui; Wu, Ping, E-mail: zjuwuping@njnu.edu.cn; Shi, Huimin; Lou, Feijian; Tang, Yawen; Zhou, Tongge; Zhou, Yiming, E-mail: zhouyiming@njnu.edu.cn; Lu, Tianhong

    2014-07-01

    Highlights: In situ magnesiothermic reduction route for the formation of porous Si@C spheres. Unique microstructural characteristics of both porous sphere and carbon matrix. Enhanced anodic performance in term of cycling stability for lithium-ion batteries. - Abstract: A novel type of porous SiC micro/nano-hybrids, i.e., porous Si spheres encapsulated in carbon shells (porous Si@C spheres), has been constructed through the pyrolysis of polyvinylidene fluoride (PVDF) and subsequent magnesiothermic reduction methodology by using SiO{sub 2} spheres as precursors. The as-synthesized porous Si@C spheres have been applied as anode materials for lithium-ion batteries (LIBs), and exhibit enhanced anodic performance in term of cycling stability compared with bare Si spheres. For example, the porous Si@C spheres are able to exhibit a high reversible capacity of 900.0 mA h g{sup ?1} after 20 cycles at a current density of 0.05 C (1 C = 4200 mA g{sup ?1}), which is much higher than that of bare Si spheres (430.7 mA h g{sup ?1})

  18. Controlled fabrication of Si nanocrystal delta-layers in thin SiO{sub 2} layers by plasma immersion ion implantation for nonvolatile memories

    SciTech Connect (OSTI)

    Bonafos, C.; Ben-Assayag, G.; Groenen, J.; Carrada, M.; Spiegel, Y.; Torregrosa, F.; Normand, P.; Dimitrakis, P.; Kapetanakis, E.; Sahu, B. S.; Slaoui, A.

    2013-12-16

    Plasma Immersion Ion Implantation (PIII) is a promising alternative to beam line implantation to produce a single layer of nanocrystals (NCs) in the gate insulator of metal-oxide semiconductor devices. We report herein the fabrication of two-dimensional Si-NCs arrays in thin SiO{sub 2} films using PIII and rapid thermal annealing. The effect of plasma and implantation conditions on the structural properties of the NC layers is examined by transmission electron microscopy. A fine tuning of the NCs characteristics is possible by optimizing the oxide thickness, implantation energy, and dose. Electrical characterization revealed that the PIII-produced-Si NC structures are appealing for nonvolatile memories.

  19. Phase Stability for the Pd-Si System. First-Principles, Experiments, and Solution-Based Modeling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhou, S. H.; Huo, Y.; Napolitano, Ralph E.

    2015-11-05

    Relative stabilities of the compounds in the binary Pd-Si system were assessed using first-principles calculations and experimental methods. Calculations of lattice parameters and enthalpy of formation indicate that Pd5Si-μ, Pd9Si2-α, Pd3 Si-β, Pd2 Si-γ, and PdSi-δ are the stable phases at 0 K (-273 °C). X-ray diffraction analyses (XRD) and electron probe microanalysis (EPMA) of the as-solidified and heat-treated samples support the computational findings, except that the PdSi-δ phase was not observed at low temperature. Considering both experimental data and first-principles results, the compounds Pd 5 Si-μ, Pd9 Si2-α, Pd3Si-β, and Pd2Si-γ are treated as stable phases down to 0more » K (-273 °C), while the PdSi-δ is treated as being stable over a limited range, exhibiting a lower bound. Using these findings, a comprehensive solution-based thermodynamic model is formulated for the Pd-Si system, permitting phase diagram calculation. Moreover, the liquid phase is described using a three-species association model and other phases are treated as solid solutions, where a random substitutional model is adopted for Pd-fcc and Si-dia, and a two-sublattice model is employed for Pd5Si-μ, Pd9Si2-α, Pd3Si-β, Pd2Si-γ, and PdSi-δ. Model parameters are fitted using available experimental data and first-principles data, and the resulting phase diagram is reported over the full range of compositions.« less

  20. Magneto-transport of an electron bilayer system in an undoped Si/SiGe double-quantum-well heterostructure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Laroche, Dominique; Huang, ShiHsien; Nielsen, Erik; Liu, Chee Wee; Li, Jiun -Yun; Lu, Tzu -Ming

    2015-04-08

    We report the design, the fabrication, and the magneto-transport study of an electron bilayer system embedded in an undoped Si/SiGe double-quantum-well heterostructure. Additionally, the combined Hall densities (n Hall ) ranging from 2.6 × 1010 cm-2 to 2.7 × 1011 cm-2 were achieved, yielding a maximal combined Hall mobility (μHall ) of 7.7 × 105 cm2/(V • s) at the highest density. Simultaneous electron population of both quantum wells is clearly observed through a Hall mobility drop as the Hall density is increased to nHall > 3.3 × 1010 cm-2, consistent with Schrödinger-Poisson simulations. Furthermore, the integer and fractional quantummore » Hall effects are observed in the device, and single-layer behavior is observed when both layers have comparable densities, either due to spontaneous interlayer coherence or to the symmetric-antisymmetric gap.« less

  1. Cycling Endurance of SONOS Non-Volatile Memory Stacks Prepared with Nitrided SiO(2)/Si(100) Intefaces

    SciTech Connect (OSTI)

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

    1999-01-11

    The effects of nitrided SiO{sub 2}/Si(100) interfaces upon cycling endurance in silicon-oxide-nitride-oxide-silicon (SONOS) non-volatile memory transistors are investigated. Analysis of MOSFET sub-threshold characteristics indicate cycling degradation to be a manifestation of interface state (D{sub it}) generation at the tunnel oxide/silicon interface. After 10{sup 6} write/erase cycles, SONOS film stacks prepared with nitrided tunnel oxides exhibit enhanced cycling endurance with {Delta}D{sub it}=3x10{sup 12} V{sup -1}cm{sup -2}, compared to {Delta}D{sub it}=2x10{sup 13} V{sup -l}cm{sup -2} for non-nitrided tunnel oxides. Additionally, if the capping oxide is formed by steam oxidation, rather than by deposition, SONOS stacks prepared with non-nitrided tunnel oxides exhibit endurance characteristics similar to stacks with nitrided tunnel oxides. From this observation it is concluded that latent nitridation of the tunnel oxidehilicon interface occurs during steam oxide cap formation.

  2. Analysis of the rotational structure in the high-resolution infrared spectra of trans-hexatriene-2-d1 and -3-d1

    SciTech Connect (OSTI)

    Craig, Norman C.; Chen, Yihui; van Besien, Herman; Blake, Thomas A.

    2014-09-01

    The 2-d1 and 3-d1 isotopologues of trans-hexatriene have been synthesized, and their high-resolution (0.0015 cm-1) IR spectra have been recorded. For each of the isotopologues the rotational structure in four C-type bands for out-of-plane vibrational modes has been analyzed, and the ground state combination differences (GSCDs) have been pooled. Ground state rotational constants have been fitted to the GSCDs. For the 2-d species, A0, B0, and C0 values of 0.7837254(5), 0.0442806(3), and 0.0419299(2) cm-1 were fitted to 2450 GSCDs. For the 3-d species, A0, B0, and C0 values of 0.7952226(8), 0.0446149(7), and 0.0422661(4) cm-1 were fitted to 2234 GSCDs. For the eleven out-of-plane modes of the two isotopologues, predictions of anharmonic wavenumbers and harmonic intensities have been computed and compared with experiment where possible.

  3. Resonances above the proton threshold in 26Si

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chipps, Kelly A.

    2016-03-06

    26Al remains an intriguing target for observational gamma-ray astronomy, thanks to its characteristic decay. The 25Al(p, )26Si reaction is part of a chain that bypasses the production of the observable 26Alg in favor of the isomeric state; its rate at novae temperatures is dominated by a resonance around 400 keV, the precise location and J assignment of which has been hotly debated. Considerable confusion in this regard has arisen from the use of outdated excitation energies and masses. Here, a reanalysis of previous work is completed to first, elucidate the confusion regarding the level structure just above the proton threshold,more »and second, provide focus to future studies.« less

  4. EA-1440-S-I: Mitigation Action Plan Completion Report

    Broader source: Energy.gov [DOE]

    This report presents the U.S. Department of Energy’s completion of the May 2008 Mitigation Action Plan (MAP) for the Supplement to the Final Site-Wide Environmental Assessment of the National Renewable Energy Laboratory’s South Table Mountain Complex (DOE/EA-1440-S-I) . Since May 2008, DOE and the National Renewable Energy Laboratory (NREL) have implemented various traffic mitigation measures and routinely monitored traffic at the NREL South Table Mountain (STM) campus in Golden, Colorado in accordance with the MAP. With the completion and occupancy of the new Research Support Facility (RSF) and Energy Systems Integration Facility (ESIF) and with offsite traffic impacts maintained below threshold levels, implementation of the MAP is hereby complete. NREL and DOE will continue to implement current traffic control measures and conduct informal traffic monitoring as part of standard operations and sustainability initiatives.

  5. Ab-initio modeling of electromechanical coupling at Si surfaces

    SciTech Connect (OSTI)

    Hoppe, Sandra; Mller, Stefan; Michl, Anja; Weissmller, Jrg

    2014-08-21

    The electromechanical coupling at the silicon (100) and (111) surfaces was studied via density functional theory by calculating the response of the ionization potential and the electron affinity to different types of strain. We find a branched strain response of those two quantities with different coupling coefficients for negative and positive strain values. This can be attributed to the reduced crystal symmetry due to anisotropic strain, which partially lifts the degeneracy of the valence and conduction bands. Only the Si(111) electron affinity exhibits a monotonously linear strain response, as the conduction band valleys remain degenerate under strain. The strain response of the surface dipole is linear and seems to be dominated by volume changes. Our results may help to understand the mechanisms behind electromechanical coupling at an atomic level in greater detail and for different electronic and atomic structures.

  6. Mechanically Activated Combustion Synthesis of MoSi2-Based Composites

    SciTech Connect (OSTI)

    Shafirovich, Evgeny

    2015-09-30

    The thermal efficiency of gas-turbine power plants could be dramatically increased by the development of new structural materials based on molybdenum silicides and borosilicides, which can operate at temperatures higher than 1300 °C with no need for cooling. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. One approach is based on the fabrication of MoSi2-Mo5Si3 composites that combine high oxidation resistance of MoSi2 and good mechanical properties of Mo5Si3. Another approach involves the addition of boron to Mo-rich silicides for improving their oxidation resistance through the formation of a borosilicate surface layer. In particular, materials based on Mo5SiB2 phase are promising materials that offer favorable combinations of high temperature mechanical properties and oxidation resistance. However, the synthesis of Mo-Si-B multi-phase alloys is difficult because of their extremely high melting temperatures. Mechanical alloying has been considered as a promising method, but it requires long milling times, leading to large energy consumption and contamination of the product by grinding media. In the reported work, MoSi2-Mo5Si3 composites and several materials based on Mo5SiB2 phase have been obtained by mechanically activated self-propagating high-temperature synthesis (MASHS). Short-term milling of Mo/Si mixture in a planetary mill has enabled a self-sustained propagation of the combustion front over the mixture pellet, leading to the formation of MoSi2-T1 composites. Combustion of Mo/Si/B mixtures for the formation of T2 phase becomes possible if the composition is designed for the addition of more exothermic reactions leading to the formation of MoB, TiC, or TiB2. Upon ignition, Mo/Si/B and Mo/Si/B/Ti mixtures exhibited spin combustion, but the products were porous, contained undesired secondary phases, and had low oxidation resistance. It has been shown that use of SHS compaction (quasi-isostatic pressing after combustion) significantly improves oxidation resistance of the obtained MoSi2-Mo5Si3 composites. The “chemical oven” technique has been successfully employed to fabricate low-porous Mo5SiB2–TiC, Mo5SiB2–TiB2, and Mo–Mo5SiB2–Mo3Si materials. Among them, Mo5SiB2–TiB2 material possesses good mechanical properties and simultaneously exhibits excellent oxidation resistance at temperatures up to 1500 °C.

  7. Facile fabrication of three-dimensional mesoporous Si/SiC composites via one-step magnesiothermic reduction at relative low temperature

    SciTech Connect (OSTI)

    Jiang, Zhihang; Ma, Yongjun; Zhou, Yong; Hu, Shanglian; Han, Chaojiang; Pei, Chonghua

    2013-10-15

    Graphical abstract: - Highlights: The Si/SiC composites were synthesized by one-step magnesiothermic reduction. The mesoporous composites have a high specific surface area (655.7 m{sup 2} g{sup ?1}). The composites exhibited a strong photoluminescence and better biocompatibility. The mechanisms of formation and photoluminescence of sample were discussed. - Abstract: By converting modified silica aerogels to the corresponding silicon/silicon carbide (Si/SiC) without losing its nanostructure, three-dimensional mesoporous (3DM) Si/SiC composites are successfully synthesized via one-step magnesothermic reduction at relative low temperature (650 C). The phase composition and microstructure of the resulting samples are measured by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). N{sub 2}-sorption isotherms results show that the products have high BrunauerEmmettTeller (BET) specific surface areas (up to 656 m{sup 2} g{sup ?1}) and narrow pore-size distributions (1.530 nm). The composites exhibit a strong photoluminescence (PL) in blue-green light region (peak centered at 533 nm). We have set out work on the biocompatibility and enhancing PL of samples. As a result of excellent performances of the composites, it can be expected to have significant application in optoelectronics, biosensors, biological tracer and so on.

  8. Method of preparing (CH.sub.3).sub.3 SiNSO and byproducts thereof

    DOE Patents [OSTI]

    Spicer, Leonard D.; Bennett, Dennis W.; Davis, Jon F.

    1984-01-01

    (CH.sub.3).sub.3 SiNSO is produced by the reaction of ((CH.sub.3).sub.3 Si).sub.2 NH with SO.sub.2. Also produced in the reaction are ((CH.sub.3).sub.3 Si).sub.2 O and a new solid compound [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ]. Both (CH.sub.3).sub.3 SiNSO and [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ] have fluorescent properties. The reaction of the subject invention is used in a method of measuring the concentration of SO.sub.2 pollutants in gases. By the method, a sample of gas is bubbled through a solution of ((CH.sub.3).sub.3 Si).sub.2 NH, whereby any SO.sub.2 present in the gas will react to produce the two fluorescent products. The measured fluorescence of these products can then be used to calculate the concentration of SO.sub.2 in the original gas sample. The solid product [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ] may be used as a standard in solid state NMR spectroscopy.

  9. Chemical reactivity of CVC and CVD SiC with UO2 at high temperatures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Silva, Chinthaka M; Katoh, Yutai; Voit, Stewart L; Snead, Lance Lewis

    2015-01-01

    Two types of silicon carbide (SiC) synthesized using two different vapor deposition processes were embedded in UO2 pellets and evaluated for their potential chemical reaction with UO2. While minor reactivity between chemical-vapor-composited (CVC) SiC and UO2 was observed at comparatively low temperatures of 1100 and 1300 C, chemical-vapor-deposited (CVD) SiC did not show any such reactivity, according to microstructural investigations. However, both CVD and CVC SiCs showed some reaction with UO2 at a higher temperature (1500 C). Elemental maps supported by phase maps obtained using electron backscatter diffraction indicated that CVC SiC was more reactive than CVD SiC at 1500more » C. Furthermore, this investigation indicated the formation of uranium carbides and uranium silicide chemical phases such as UC, USi2, and U3Si2 as a result of SiC reaction with UO2.« less

  10. Low Cost SiOx-Graphite and Olivine Materials | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    09 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. PDF icon es_19_zaghib.pdf More Documents & Publications Low Cost SiOx-Graphite and Olivine Materials Phase Behavior and Solid State Chemistry in Olivines Low Cost SiOx-Graphite and High Voltage Spinel Cathode

  11. Ultrathin nanosheets of CrSiTe3: A semiconducting two-dimensional ferromagnetic material

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lin, Ming -Wei; Zhung, Houlong L.; Yan, Jiaqiang; Ward, Thomas Zac; Puretzky, Alexander A.; Rouleau, Christopher M.; Gai, Zheng; Liang, Liangbo; Meunier, Vincent; Ganesh, Panchapakesan; et al

    2015-11-27

    Finite range ferromagnetism and antiferromagnetism in two-dimensional (2D) systems within an isotropic Heisenberg model at non-zero temperature were originally proposed to be impossible. However, recent theoretical studies using an Ising model have recently shown that 2D magnetic crystals can exhibit magnetism. Experimental verification of existing 2D magnetic crystals in this system has remained elusive. In this work we for the first time exfoliate the CrSiTe3, a bulk ferromagnetic semiconductor, to mono- and few-layer 2D crystals onto a Si/SiO2 substrate. The Raman spectra show the good stability and high quality of the exfoliated flakes, consistent with the computed phonon spectra ofmore » 2D CrSiTe3, giving a strong evidence for the existence of 2D CrSiTe3 crystals. When the thickness of the CrSiTe3 crystals is reduced to few-layers, we observed a clear change in resistivity at 80~120 K, consistent with the theoretical calculations on the Curie temperature (Tc) of ~80 K for the magnetic ordering of 2D CrSiTe3 crystals. As a result, the ferromagnetic mono- and few-layer 2D CrSiTe3 indicated here should enable numerous applications in nano-spintronics.« less

  12. Numerical analysis for high-efficiency GaAs solar cells fabricated on Si substrates

    SciTech Connect (OSTI)

    Yamaguchi, M.; Amano, C.; Itoh, Y.

    1989-07-15

    This paper describes some recent developments in GaAs thin-film solar cells fabricated on Si substrates by metalorganic chemical vapor deposition and numerically analyzes them.GaAs solar cells with efficiency of more than 18% are successfully fabricated on Si substrates by reducing the dislocation density. Photovoltaic properties of GaAs/Si cells are analyzed by considering the effect of nonuniform dislocation distribution on recombination properties of GaAs thin films on Si substrates. Numerical analysis shows that the effect of majority-carrier trapping must be considered. High efficiency GaAs solar cells with total-area efficiency of over 20% on Si substrates can be realized if dislocation density can be reduced to less than 5/times/10/sup 5/ cm/sup /minus/2/.

  13. Effects of aluminum on epitaxial graphene grown on C-face SiC

    SciTech Connect (OSTI)

    Xia, Chao Johansson, Leif I.; Hultman, Lars; Virojanadara, Chariya; Niu, Yuran

    2015-05-21

    The effects of Al layers deposited on graphene grown on C-face SiC substrates are investigated before and after subsequent annealing using low energy electron diffraction (LEED), photoelectron spectroscopy, and angle resolved photoemission. As-deposited layers appear inert. Annealing at a temperature of about 400?C initiates migration of Al through the graphene into the graphene/SiC interface. Further annealing at temperatures from 500?C to 700?C induces formation of an ordered compound, producing a two domain ?7??7R19 LEED pattern and significant changes in the core level spectra that suggest formation of an Al-Si-C compound. Decomposition of this compound starts after annealing at 800?C, and at 1000?C, Al is no longer possible to detect at the surface. On Si-face graphene, deposited Al layers did not form such an Al-Si-C compound, and Al was still detectable after annealing above 1000?C.

  14. Model of U3Si2 Fuel System using BISON Fuel Code

    SciTech Connect (OSTI)

    K. E. Metzger; T. W. Knight; R. L. Williamson

    2014-04-01

    This research considers the proposed advanced fuel system: U3Si2 combined with an advanced cladding. U3Si2 has a number of advantageous thermophysical properties, which motivate its use as an accident tolerant fuel. This preliminary model evaluates the behavior of U3Si2 using available thermophysical data to predict the cladding-fuel pellet temperature and stress using the fuel performance code: BISON. The preliminary results obtained from the U3Si2 fuel model describe the mechanism of Pellet-Clad Mechanical Interaction for this system while more extensive testing including creep testing of U3Si2 is planned for improved understanding of thermophysical properties for predicting fuel performance.

  15. Heat Pipe Embedded AlSiC Plates for High Conductivity - Low CTE Heat Spreaders

    SciTech Connect (OSTI)

    Johnson, Matthew ); Weyant, J.; Garner, S. ); Occhionero, M. )

    2010-01-07

    Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal conductivities ranging between 50,000 and 200,000 W/m-K, depending on the heat pipe length. Installing heat pipes into an AlSiC plate dramatically increases the plates effective thermal conductivity. AlSiC plates alone have a thermal conductivity of roughly 200 W/m-K and a CTE ranging from 7-12 ppm/ deg C, similar to that of silicon. An equivalent sized heat pipe embedded AlSiC plate has effective thermal conductivity ranging from 400 to 500 W/m-K and retains the CTE of AlSiC.

  16. Towards III-V solar cells on Si: Improvement in the crystalline quality of Ge-on-Si virtual substrates through low porosity porous silicon buffer layer and annealing

    SciTech Connect (OSTI)

    Calabrese, Gabriele; Baricordi, Stefano; Bernardoni, Paolo; Fin, Samuele; Guidi, Vincenzo; Vincenzi, Donato

    2014-09-26

    A comparison between the crystalline quality of Ge grown on bulk Si and on a low porosity porous Si (pSi) buffer layer using low energy plasma enhanced chemical vapor deposition is reported. Omega/2Theta coupled scans around the Ge and Si (004) diffraction peaks show a reduction of the Ge full-width at half maximum (FWHM) of 22.4% in presence of the pSi buffer layer, indicating it is effective in improving the epilayer crystalline quality. At the same time atomic force microscopy analysis shows an increase in root means square roughness for Ge grown on pSi from 38.5 nm to 48.0 nm, as a consequence of the larger surface roughness of pSi compared to bulk Si. The effect of 20 minutes vacuum annealing at 580C is also investigated. The annealing leads to a FWHM reduction of 23% for Ge grown on Si and of 36.5% for Ge on pSi, resulting in a FWHM of 101 arcsec in the latter case. At the same time, the RMS roughness is reduced of 8.8% and of 46.5% for Ge grown on bulk Si and on pSi, respectively. The biggest improvement in the crystalline quality of Ge grown on pSi with respect to Ge grown on bulk Si observed after annealing is a consequence of the simultaneous reorganization of the Ge epilayer and the buffer layer driven by energy minimization. A low porosity buffer layer can thus be used for the growth of low defect density Ge on Si virtual substrates for the successive integration of III-V multijunction solar cells on Si. The suggested approach is simple and fast thus allowing for high throughput-, moreover is cost effective and fully compatible with subsequent wafer processing. Finally it does not introduce new chemicals in the solar cell fabrication process and can be scaled to large area silicon wafers.

  17. Role of Si on the Diffusional Interactions between U-Mo and Al-Si Alloys at 823 K (550 degrees C)

    SciTech Connect (OSTI)

    E. Perez; Y.H. Sohn; D.D. Keiser, Jr.

    2013-01-01

    U-Mo dispersions in Al-alloy matrix and monolithic fuels encased in Al-alloy are under development to fulfill the requirements for research and test reactors to use low-enriched molybdenum stabilized uranium alloys fuels. Significant interaction takes place between the U-Mo fuel and Al during manufacturing and in-reactor irradiation. The interactions products are Al-rich phases with physical and thermal characteristics that adversely affect fuel performance and lead to premature failure. Detailed analysis of the interdiffusion and microstructural development of this system was carried through diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo in contact with pure Al, Al-2wt.%Si, and Al-5wt.%Si, annealed at 823K for 1, 5 and 20 hours. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed for the analysis. Diffusion couples consisting of U-Mo vs. pure Al contained UAl3, UAl4, U6Mo4Al43, and UMo2Al20 phases. The addition of Si to the Al significantly reduced the thickness of the interdiffusion zone. The interdiffusion zones developed Al and Si enriched regions, whose locations and size depended on the Si and Mo concentrations in the terminal alloys. In the couples, the (U,Mo)(Al,Si)3 phase was observed throughout interdiffusion zone, and the U6Mo4Al43 and UMo2Al20 phases were observed only where the Si concentrations were low.

  18. Low-Defect Heteroepitaxy on Porous Si Substrates: Cooperative Research and Development Final Report, CRADA Number CRD-13-534

    SciTech Connect (OSTI)

    Lee, B.

    2014-12-01

    In this collaboration, NREL will grow Ge, SiGe, and III-V layers on porous Si (pSi) substrates prepared either by Crystal Solar or at NREL. The intent is to grow low-defect epitaxial III-V alloys using the porous Si layer to prevent defect formation. Finally, we aim to fabricate solar cells from the III-V layers to prove the electronic quality.

  19. Potential improvements in SiGe radioisotope thermoelectric generator performance

    SciTech Connect (OSTI)

    Mowery, A.L.

    1999-01-01

    In accordance with NASA{close_quote}s slogan: {open_quotes}Better, Cheaper, Faster,{close_quotes} this paper will address potential improvements to SiGe RTG technology to make them Better. RTGs are doubtless cheaper than {open_quotes}paper designs{close_quotes} which are better and cheaper until development, performance and safety test costs are considered. RTGs have the advantage of being fully developed and tested in the rigors of space for over twenty years. Further, unless a new system can be accelerated tested, as were the RTGs, they cannot be deployed reliably unless a number of systems have succeeded for test periods exceeding the mission lifetime. Two potential developments are discussed that can improve the basic RTG performance by 10 to 40{sup +}{percent} depending on the mission profile. These improvements could be demonstrated in years. Accelerated testing could also be performed in this period to preserve existing RTG reliability. Data from a qualification tested RTG will be displayed, while not definitive, to support the conclusions. Finally, it is anticipated that other investigators will be encouraged to suggest further modifications to the basic RTG design to improve its performance. {copyright} {ital 1999 American Institute of Physics.}

  20. Indium Growth and Island Height Control on Si Submonolayer Phases

    SciTech Connect (OSTI)

    Chen, Jizhou

    2009-05-09

    Nanotechnology refers any technique that involves about object with nanoscale (10{sup -9} m) or even smaller. It has become more and more important in recently years and has changed our world dramatically. Most of modern electronic devices today should thanks to the miniaturizing driven by development of nanotechnology. Recent years, more and more governments are investing huge amount of money in research related to nanotechnology. There are two major reasons that nanostructure is so fascinate. The first one is the miniaturizing. It is obvious that if we can make products smaller without losing the features, we can save the cost and increase the performance dramatically. For an example, the first computer in the world, ENIAC, which occupied several rooms, is less powerful than the cheapest calculator today. Today's chips with sizes of less than half an inch contain millions of basic units. All these should thank to the development of nanotechnology. The other reason is that when we come to nanoscale, there are many new effects due to the quantum effect which can't be found in large systems. For an example, quantum dots (QDs) are systems which sizes are below 1{micro}m(10{sup -6}m) and restricted in three dimensions. There are many interesting quantum effects in QDs, including discrete energy levels, and interdot coupling. Due to these properties and their small sizes, QDs have varies potential applications such as quantum computing, probe, light emitting device, solar cells, and laser. To meet the requirement of the nanoelectrical applications, the QDs must be grown highly uniformly because their property is highly dependent on their sizes. The major methods to grow uniform QDs include epitaxial, and lithograph. Lithography is a process to make patterns on a thin film by selectively removing certain parts of the film. Using this method, people have good control over size, location and spacing of QDs. For an example, the Extreme ultraviolet lithography (EUVL) have a wave length of 13.4nm so it can curve on the surface of an sample to make structure as small as the order of 10nm. however, lithograph usually causes permanent damages to the surface and in many cases the QDs are damaged during the lithograph and therefore result in high percentage of defects. Quantum size effect has attracted more and more interests in surface science due to many of its effects. One of its effects is the height preference in film growing and the resulting possibility of uniformly sized self-assemble nanostructure. The experiment of Pb islands on In 4x1 phase shows that both the height and the width can be controlled by proper growth conditions, which expands the growth dimensions from 1 to 2. This discover leads us to study the In/Pb interface. In Ch.3, we found that the Pb islands growing on In 4x1-Si(111) surface which have uniform height due to QSE and uniform width due to the constriction of In 4x1 lattice have unexpected stability. These islands are stable in even RT, unlike usual nanostructures on Pb/Si surface which are stable only at low temperature. Since similar structures are usually grown at low temperature, this discovery makes the grown structures closer to technological applications. It also shows the unusual of In/Pb interface. Then we studied the In islands grown on Pb-{alpha}-{radical}3x{radical}3-Si(111) phase in Ch.4. These islands have fcc structure in the first few layers, and then convert to bct structure. The In fcc islands have sharp height preference due to QSE like Pb islands. However, the preferred height is different (7 layer for Pb on Si 7x7 and 4 layer for Pb on In 4x1), due to the difference of interface. The In islands structure prefers to be bct than fcc with coverage increase. It is quantitatively supported by first-principle calculation. Unexpectedly, the In islands grown on various of In interfaces didn't show QSE effects and phase transition from fcc and bct structures as on the Pb-{alpha} interface (Ch.6). In g(s) curve there is no clear oscillations in the g(s) curve as the In on Pb-{alpha} phase. This

  1. Combustion control technologies for direct injection SI engine

    SciTech Connect (OSTI)

    Kume, T.; Iwamoto, Y.; Iida, K.; Murakami, M.; Akishino, K.; Ando, H.

    1996-09-01

    Novel combustion control technologies for the direct injection SI engine have been developed. By adopting upright straight intake ports to generate air tumble, an electromagnetic swirl injector to realize optimized spray dispersion and atomization and a compact piston cavity to maintain charge stratification, it has become possible to achieve super-lean stratified combustion for higher thermal efficiency under partial loads as well as homogeneous combustion to realize higher performance at full loads. At partial loads, fuel is injected into the piston cavity during the later stage of the compression stroke. Any fuel spray impinging on the cavity wall is directed to the spark plug. Tumbling air flow in the cavity also assists the conservation of the rich mixture zone around the spark plug. Stable combustion can be realized under a air fuel ratio exceeding 40. At higher loads, fuel is injected during the early stage of the intake stroke. Since air cooling by the latent heat of vaporization increases volumetric efficiency and reduces the octane number requirement, a high compression ratio of 12 to 1 can be adopted. As a result, engines utilizing these types of control technologies show a 10% increase in improved performance over conventional port injection engines.

  2. Pt silicide/poly-Si Schottky diodes as temperature sensors for bolometers

    SciTech Connect (OSTI)

    Yuryev, V. A. Chizh, K. V.; Chapnin, V. A.; Mironov, S. A.; Dubkov, V. P.; Uvarov, O. V.; Kalinushkin, V. P.; Senkov, V. M.; Nalivaiko, O. Y.; Novikau, A. G.; Gaiduk, P. I.

    2015-05-28

    Platinum silicide Schottky diodes formed on films of polycrystalline Si doped by phosphorus are demonstrated to be efficient and manufacturable CMOS-compatible temperature sensors for microbolometer detectors of radiation. Thin-film platinum silicide/poly-Si diodes have been produced by a CMOS-compatible process on artificial Si{sub 3}N{sub 4}/SiO{sub 2}/Si(001) substrates simulating the bolometer cells. Layer structure and phase composition of the original Pt/poly-Si films and the Pt silicide/poly-Si films synthesized by a low-temperature process have been studied by means of the scanning transmission electron microscopy; they have also been explored by means of the two-wavelength X-ray structural phase analysis and the X-ray photoelectron spectroscopy. Temperature coefficient of voltage for the forward current of a single diode is shown to reach the value of about ?2%/?C in the temperature interval from 25 to 50?C.

  3. GaAs buffer layer technique for vertical nanowire growth on Si substrate

    SciTech Connect (OSTI)

    Xu, Xiaoqing Parizi, Kokab B.; Huo, Yijie; Kang, Yangsen; Philip Wong, H.-S.; Li, Yang

    2014-02-24

    Gold catalyzed vapor-liquid-solid method is widely applied to IIIV nanowire (NW) growth on Si substrate. However, the easy oxidation of Si, possible Si contamination in the NWs, high defect density in the NWs, and high sensitivity of the NW morphology to growth conditions largely limit its controllability. In this work, we developed a buffer layer technique by introducing a GaAs thin film with predefined polarity as a template. It is found that samples grown on these buffer layers all have high vertical NW yields in general, due to the single-orientation of the buffer layers. Low temperature buffer with smoother surface leads to highest yield of vertical NWs, while high temperature (HT) buffer with better crystallinity results in perfect NW quality. The defect-free property we observed here is very promising for optoelectronic device applications based on GaAs NW. Moreover, the buffer layers can eliminate Si contamination by preventing Si-Au alloy formation and by increasing the thickness of the Si diffusion barrier, thus providing more flexibility to vertical NW growth. The buffer layer technique we demonstrated here could be easily extended to other III-V on Si system for electronic and photonic applications.

  4. Thermal stability of photovoltaic a-Si:H determined by neutron reflectometry

    SciTech Connect (OSTI)

    Qviller, A. J. Haug, H.; You, C. C.; Hasle, I. M.; Marstein, E. S.; Frommen, C.; Hauback, B. C.; Dennison, A. J. C.; Vorobiev, A.; streng, E.; Fjellvg, H.; Hjrvarsson, B.

    2014-12-08

    Neutron and X-ray reflectometry were used to determine the layer structure and hydrogen content of thin films of amorphous silicon (a-Si:H) deposited onto crystalline silicon (Si) wafers for surface passivation in solar cells. The combination of these two reflectometry techniques is well suited for non-destructive probing of the structure of a-Si:H due to being able to probe buried interfaces and having sub-nanometer resolution. Neutron reflectometry is also unique in its ability to allow determination of density gradients of light elements such as hydrogen (H). The neutron scattering contrast between Si and H is strong, making it possible to determine the H concentration in the deposited a-Si:H. In order to correlate the surface passivation properties supplied by the a-Si:H thin films, as quantified by obtainable effective minority carrier lifetime, photoconductance measurements were also performed. It is shown that the minority carrier lifetime falls sharply when H has been desorbed from a-Si:H by annealing.

  5. Optoelectronic properties of Mg{sub 2}Si semiconducting layers with high absorption coefficients

    SciTech Connect (OSTI)

    Kato, Takashi; Sago, Yuichiro; Fujiwara, Hiroyuki

    2011-09-15

    In an attempt to develop a low-cost material for solar cell devices, polycrystalline magnesium silicide (poly-Mg{sub 2}Si) semiconducting layers have been prepared by applying rf magnetron sputtering using a Mg{sub 2}Si target. The optimum substrate temperature for the poly-Mg{sub 2}Si growth was found to be T{sub s} = 200 deg. C; the film deposition at higher temperatures leads to desorption of Mg atoms from the growing surface, while the amorphous phase formation occurs at room temperature. The poly-Mg{sub 2}Si layer deposited at T{sub s} = 200 deg. C shows the (111) preferential orientation with a uniform grain size of {approx}50 nm. The dielectric function of the poly-Mg{sub 2}Si layer has been determined accurately by spectroscopic ellipsometry. From the analysis, quite high absorption coefficients and an indirect gap of 0.77 eV in the poly-Mg{sub 2}Si layer have been confirmed. The above poly-Mg{sub 2}Si layer shows clear photoconductivity and can be applied as a narrow-gap bottom layer in multi-junction solar cell devices.

  6. Influence of annealing atmosphere on the magnetic properties of SiO{sub 2}/Fe/SiO{sub 2} sandwiched nanocomposite films

    SciTech Connect (OSTI)

    Zhu, P. L.; Liu, Z.; Fan, Y. L.; Jiang, Z. M.; Yang, X. J.; Xue, F.

    2009-08-15

    The magnetic properties of SiO{sub 2}/Fe/SiO{sub 2} nanocomposite films are studied by magnetic force microscopy and vibrating sample magnetometer. The films were fabricated by alternately depositing SiO{sub 2}, Fe, and SiO{sub 2} on Si substrates with magnetron sputtering followed by thermal annealing. It is found that the annealing atmosphere significantly influences the sample structure, composition, and magnetic properties. The samples annealed in forming gas show much better magnetic properties than those annealed in vacuum and in N{sub 2}. The saturation magnetization can reach 200 emu/g, fairly close to the value of bulk Fe, and the coercivity can reach 400 Oe, much higher than 10 Oe of the bulk Fe. X-ray photoelectron spectroscopic depth profile measurement was carried out to study the mechanism of the strong influence of annealing atmosphere. For the samples annealed in forming gas, Fe nanoparticles are mildly oxidized, forming thin shells of Fe{sub 2}O{sub 3} surrounding them, which is beneficial for maintaining the ferromagnetic behavior and enhancing the coercivity of nanoparticles.

  7. Potential variation around grain boundaries in BaSi{sub 2} films grown on multicrystalline silicon evaluated using Kelvin probe force microscopy

    SciTech Connect (OSTI)

    Baba, Masakazu; Tsukahara, Daichi; Toko, Kaoru; Hara, Kosuke O.; Usami, Noritaka; Sekiguchi, Takashi; Suemasu, Takashi

    2014-12-21

    Potential variations across the grain boundaries (GBs) in a 100?nm thick undoped n-BaSi{sub 2} film on a cast-grown multicrystalline Si (mc-Si) substrate are evaluated using Kelvin probe force microscopy (KFM). The ?-2? X-ray diffraction pattern reveals diffraction peaks, such as (201), (301), (410), and (411) of BaSi{sub 2}. Local-area electron backscatter diffraction reveals that the a-axis of BaSi{sub 2} is tilted slightly from the surface normal, depending on the local crystal plane of the mc-Si. KFM measurements show that the potentials are not significantly disordered in the grown BaSi{sub 2}, even around the GBs of mc-Si. The potentials are higher at GBs of BaSi{sub 2} around Si GBs that are formed by grains with a Si(111) face and those with faces that deviate slightly from Si(111). Thus, downward band bending occurs at these BaSi{sub 2} GBs. Minority carriers (holes) undergo a repelling force near the GBs, which may suppress recombination as in the case of undoped n-BaSi{sub 2} epitaxial films on a single crystal Si(111) substrate. The barrier height for hole transport across the GBs varies in the range from 10 to 55?meV. The potentials are also higher at the BaSi{sub 2} GBs grown around Si GBs composed of grains with Si(001) and Si(111) faces. The barrier height for hole transport ranges from 5 to 55?meV. These results indicate that BaSi{sub 2} GBs formed on (111)-dominant Si surfaces do not have a negative influence on the minority-carrier properties, and thus BaSi{sub 2} formed on underlayers, such as (111)-oriented Si or Ge and on (111)-oriented mc-Si, can be utilized as a solar cell active layer.

  8. Dimensional isotropy of 6H and 3C SiC under neutron irradiation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki; Terrani, Kurt A.; Specht, Eliot D.

    2016-01-16

    This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.02–20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstrated equivalent swelling behavior.more » Moreover the 6H–SiC expanded isotropically. The magnitude of the swelling followed a ~0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ~7.8% volume expansion in SiC was observed prior to amorphization. Above ~0.9 × 1025 n/m2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm3. As a result, the as-amorphized density was the same at the 2 × 1025 and 2 × 1026 n/m2 (E > 0.1 MeV) dose levels.« less

  9. Oxidation of step edges on vicinal 4H-SiC(0001) surfaces

    SciTech Connect (OSTI)

    Li, Wenbo; Zhu, Qiaozhi; Wang, Dejun, E-mail: dwang121@dlut.edu.cn [School of Electronic Science and Technology, Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)] [School of Electronic Science and Technology, Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Zhao, Jijun [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), College of Advanced Science and Technology, Ministry of Education, Dalian 116024 (China)] [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), College of Advanced Science and Technology, Ministry of Education, Dalian 116024 (China)

    2013-11-18

    The oxidation processes of stepped SiC(0001) surfaces are studied within the ab initio atomistic thermodynamics approach. Our calculations show that a one-dimensional -Si-O- chain structure as a precursor for oxide growth on stepped SiC surfaces is formed along the step edge, promoting further oxidation of the step edges. Following the modified Deal-Grove oxidation model, we also find that the oxidation rate at steps is higher than that at terraces by three orders of magnitude. These findings give a reasonable explanation for the oxide thickness fluctuation between the step and the terrace observed in the previous experiments.

  10. Moment enhancement in dilute magnetic semiconductors: MnxSi1-x with x =

    Office of Scientific and Technical Information (OSTI)

    0.1% (Journal Article) | SciTech Connect Moment enhancement in dilute magnetic semiconductors: MnxSi1-x with x = 0.1% Citation Details In-Document Search Title: Moment enhancement in dilute magnetic semiconductors: MnxSi1-x with x = 0.1% The experimentally determined magnetic moments/Mn, M, in Mn{sub x}Si{sub 1-x} are considered, with particular attention to the case with 5.0 {micro}{sub B}/Mn, obtained for x = 0.1%. The existing theoretical M values for neutral Mn range from 2.83 to 3.78

  11. PID-free C-Si PV Module Using Novel Chemically-Tempered Glass | Department

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of Energy PID-free C-Si PV Module Using Novel Chemically-Tempered Glass PID-free C-Si PV Module Using Novel Chemically-Tempered Glass Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PDF icon pvmrw13_ps4_aist_kambe.pdf More Documents & Publications EXPERIENCES ON PID TESTING OF PV MODULES IN 2012 Agenda for the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PID Failure of c-Si and Thin-Film Modules and Possible Correlation

  12. Unexpected formal insertion of CO2 into the C-Si bonds of a zinc compound

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kemp, Richard A.; McGrew, Genette I.; Khatri, Pathik A.; Geiger, William E.; Waterman, Rory

    2015-09-08

    Reaction of [κ2-PR2C(SiMe3)Py]2Zn (R = Ph, 2a; iPr, 2b) with CO2 affords the products of formal insertion at the C–Si bond, [κ2-PR2CC(O)O(SiMe3)Py]2Zn (R = Ph, 3a; iPr, 3b). Insertion product 3b was structurally characterized. As a result, the reaction appears to be a stepwise insertion and rearrangement of CO2 based on kinetic data.

  13. Barocaloric effect in the magnetocaloric prototype Gd5Si2Ge2 (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Barocaloric effect in the magnetocaloric prototype Gd5Si2Ge2 Citation Details In-Document Search Title: Barocaloric effect in the magnetocaloric prototype Gd5Si2Ge2 We report on calorimetric measurements under hydrostatic pressure that enabled us to determine the barocaloric effect in Gd5Si2Ge2. The values for the entropy change for moderate pressures compare favourably to those corresponding to the magnetocaloric effect in this compound. Entropy data are

  14. Microporous SiO{sub 2} with huge electric-double-layer capacitance for

    Office of Scientific and Technical Information (OSTI)

    low-voltage indium tin oxide thin-film transistors (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Microporous SiO{sub 2} with huge electric-double-layer capacitance for low-voltage indium tin oxide thin-film transistors Citation Details In-Document Search Title: Microporous SiO{sub 2} with huge electric-double-layer capacitance for low-voltage indium tin oxide thin-film transistors Electric-double-layer (EDL) effect is observed in microporous SiO{sub 2}

  15. PID Failure of c-Si and Thin-Film Modules and Possible Correlation with

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Leakage Currents | Department of Energy PID Failure of c-Si and Thin-Film Modules and Possible Correlation with Leakage Currents PID Failure of c-Si and Thin-Film Modules and Possible Correlation with Leakage Currents This PowerPoint presentation was originally presented at the NREL 2013 PV Module Reliability Workshop on Feb. 26-27, 2013 in Golden, CO. Presented by ZSW, it discussed PID failure of c-Si and thin-film modules, power degredation, the evaluation of leakage currents from the lab

  16. Sensitivities of I-V Parameters in C-Si PV Modules of Hygrothermal Stress |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Sensitivities of I-V Parameters in C-Si PV Modules of Hygrothermal Stress Sensitivities of I-V Parameters in C-Si PV Modules of Hygrothermal Stress Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PDF icon pvmrw13_ps4_espec_suzuki.pdf More Documents & Publications The Acceleration of Degradation by HAST and Air-HAST in c-Si PV Modules Agenda for the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado Thermal

  17. Atomic configuration of irradiation-induced planar defects in 3C-SiC

    SciTech Connect (OSTI)

    Lin, Y. R. [Department of Engineering and System Science, National Tsing-Hua University, Hsinchu 30013, Taiwan (China); National Synchrotron Radiation Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Ho, C. Y. [Institute of Nuclear Engineering and Science, National Tsing-Hua University, Hsinchu 30013, Taiwan (China); Hsieh, C. Y.; Chang, M. T.; Lo, S. C. [Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan (China); Chen, F. R. [Department of Engineering and System Science, National Tsing-Hua University, Hsinchu 30013, Taiwan (China); Kai, J. J., E-mail: ceer0001@gmail.com [Department of Engineering and System Science, National Tsing-Hua University, Hsinchu 30013, Taiwan (China); Institute of Nuclear Engineering and Science, National Tsing-Hua University, Hsinchu 30013, Taiwan (China)

    2014-03-24

    The atomic configuration of irradiation-induced planar defects in single crystal 3C-SiC at high irradiation temperatures was shown in this research. A spherical aberration corrected scanning transmission electron microscope provided images of individual silicon and carbon atoms by the annular bright-field (ABF) method. Two types of irradiation-induced planar defects were observed in the ABF images including the extrinsic stacking fault loop with two offset Si-C bilayers and the intrinsic stacking fault loop with one offset Si-C bilayer. The results are in good agreement with images simulated under identical conditions.

  18. The Acceleration of Degradation by HAST and Air-HAST in c-Si PV Modules |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy The Acceleration of Degradation by HAST and Air-HAST in c-Si PV Modules The Acceleration of Degradation by HAST and Air-HAST in c-Si PV Modules Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PDF icon pvmrw13_ps4_espc_suzuki.pdf More Documents & Publications Sensitivities of I-V Parameters in C-Si PV Modules of Hygrothermal Stress Agenda for the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado

  19. Magnetic structure of the antiferromagnetic Kondo lattice compounds CeRhAl4Si2 and CeIrAl4Si2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ghimire, N. J.; Calder, S.; Janoschek, M.; Bauer, E. D.

    2015-06-01

    In this article, we have investigated the magnetic ground state of the antiferromagnetic Kondo-lattice compounds CeMAl4Si2(M = Rh, Ir) using neutron powder diffraction. Although both of these compounds show two magnetic transitions TN1 and TN2 in the bulk properties measurements, evidence for magnetic long-range order was only found below the lower transition TN2. Analysis of the diffraction profiles reveals a commensurate antiferromagnetic structure with a propagation vector k = (0, 0, 1/2). The magnetic moment in the ordered state of CeRhAl4Si2 and CeIrAl4Si2 were determined to be 1.14(2) and 1.41(3) μB/Ce, respectively, and are parallel to the crystallographic c-axis inmore » agreement with magnetic susceptibility measurements.« less

  20. Elastic tunneling charge transport mechanisms in silicon quantum dots /SiO{sub 2} thin films and superlattices

    SciTech Connect (OSTI)

    Illera, S. Prades, J. D.; Cirera, A.

    2015-05-07

    The role of different charge transport mechanisms in Si/SiO{sub 2} structures has been studied. A theoretical model based on the Transfer Hamiltonian Formalism has been developed to explain experimental current trends in terms of three different elastic tunneling processes: (1) trap assisted tunneling; (2) transport through an intermediate quantum dot; and (3) direct tunneling between leads. In general, at low fields carrier transport is dominated by the quantum dots whereas, for moderate and high fields, transport through deep traps inherent to the SiO{sub 2} is the most relevant process. Besides, current trends in Si/SiO{sub 2} superlattice structure have been properly reproduced.

  1. Temperature dependence of contact resistance for Au-Ti-Pd{sub 2}Si-n{sup +}-Si ohmic contacts subjected to microwave irradiation

    SciTech Connect (OSTI)

    Belyaev, A. E.; Boltovets, N. S.; Konakova, R. V. Kudryk, Ya. Ya.; Sachenko, A. V.; Sheremet, V. N.; Vinogradov, A. O.

    2012-03-15

    Based on a theoretical analysis of the temperature dependence of the contact resistance R{sub c} for an Au-Ti-Pd{sub 2}Si-n{sup +}-Si ohmic contact, a current-transfer mechanism explaining the experimentally observed increase in R{sub c} in the temperature range 100-380 K is proposed. It is shown that microwave treatment of such contacts results in a decrease in the spread of R{sub c} over the wafer and a decrease in the value of R{sub c} whilst retaining an increase in R{sub c} in the temperatures range 100-380 K.

  2. Selective growth of Pb islands on graphene/SiC buffer layers

    SciTech Connect (OSTI)

    Liu, X. T.; Miao, Y. P.; Ma, D. Y.; Hu, T. W.; Ma, F. E-mail: kwxu@mail.xjtu.edu.cn; Chu, Paul K.; Xu, K. W. E-mail: kwxu@mail.xjtu.edu.cn

    2015-02-14

    Graphene is fabricated by thermal decomposition of silicon carbide (SiC) and Pb islands are deposited by Pb flux in molecular beam epitaxy chamber. It is found that graphene domains and SiC buffer layer coexist. Selective growth of Pb islands on SiC buffer layer rather than on graphene domains is observed. It can be ascribed to the higher adsorption energy of Pb atoms on the 6?(3) reconstruction of SiC. However, once Pb islands nucleate on graphene domains, they will grow very large owing to the lower diffusion barrier of Pb atoms on graphene. The results are consistent with first-principle calculations. Since Pb atoms on graphene are nearly free-standing, Pb islands grow in even-number mode.

  3. SbSI nanocrystal formation in AsSbSI glass under laser beam

    SciTech Connect (OSTI)

    Azhniuk, Yu.M.; Stoyka, V.; Petryshynets, I.; Rubish, V.M.; Guranich, O.G.; Gomonnai, A.V.; Zahn, D.R.T.

    2012-06-15

    Highlights: ? AsSbSI glasses are obtained by co-melting of As{sub 2}S{sub 3} and SbSI. ? The glass structure and composition are confirmed by SEM, EDX, and Raman studies. ? Laser-induced crystallization of SbSI from the glass is observed by Raman spectroscopy. -- Abstract: AsSbSI glasses are obtained by co-melting of As{sub 2}S{sub 3} and SbSI in a broad compositional interval. Their structure and composition are confirmed by the studies of scanning electron microscopy, energy dispersive X-ray spectroscopy, and micro-Raman scattering. Laser-induced crystallization of SbSI crystallites from the glass matrix is observed in the course of the micro-Raman measurement as a result of local laser beam heating.

  4. Reducing c-Si Module Operating Temperature via PV Packaging Components...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Agenda for the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PID Failure of c-Si and Thin-Film Modules and Possible Correlation with Leakage Currents ...

  5. Crystallization from high temperature solutions of Si in Cu/Al solvent

    DOE Patents [OSTI]

    Ciszek, Theodore F.; Wang, Tihu

    1996-01-01

    A liquid phase epitaxy method for forming thin crystalline layers of device quality silicon having less than 3.times.10.sup.16 Cu atoms/cc impurity, comprising: preparing a saturated liquid solution of Si in a Cu/Al solvent at about 20 to about 40 at. % Si at a temperature range of about 850.degree. to about 1100.degree. C. in an inert gas; immersing or partially immersing a substrate in the saturated liquid solution; super saturating the solution by lowering the temperature of the saturated solution; holding the substrate in the saturated solution for a period of time sufficient to cause Si to precipitate out of solution and form a crystalline layer of Si on the substrate; and withdrawing the substrate from the solution.

  6. Crystallization from high temperature solutions of Si in Cu/Al solvent

    DOE Patents [OSTI]

    Ciszek, T.F.; Wang, T.

    1996-08-13

    A liquid phase epitaxy method is disclosed for forming thin crystalline layers of device quality silicon having less than 3{times}10{sup 16} Cu atoms/cc impurity, comprising: preparing a saturated liquid solution of Si in a Cu/Al solvent at about 20 to about 40 at. % Si at a temperature range of about 850 to about 1100 C in an inert gas; immersing or partially immersing a substrate in the saturated liquid solution; super saturating the solution by lowering the temperature of the saturated solution; holding the substrate in the saturated solution for a period of time sufficient to cause Si to precipitate out of solution and form a crystalline layer of Si on the substrate; and withdrawing the substrate from the solution. 3 figs.

  7. Breakthrough in Power Electronics from SiC: May 25, 2004 - May 31, 2005

    SciTech Connect (OSTI)

    Marckx, D. A.

    2006-03-01

    This report explores the premise that silicon carbide (SiC) devices would reduce substantially the cost of energy of large wind turbines that need power electronics for variable speed generation systems.

  8. Low-cost, high-efficiency solar cells utilizing GaAs-on-Si technology

    SciTech Connect (OSTI)

    Vernon, S.M. )

    1993-04-01

    This report describes work to develop technology to deposit GaAs on Si using a nucleation layer of atomic-layer-epitaxy-grown GaAs or AlAs on Si. This ensures two-dimensional nucleation and should lead to fewer defects in the final GaAs layer. As an alternative, we also developed technology for depositing GaAs on sawtooth-patterned Si. Preliminary studies showed that this material can have a very low defect density, [approximately] 1 [times] 10[sup 5] cm[sup [minus]5], as opposed to our conventionally grown GaAs on SL which has a typical defect density of over 1 [times]10[sup 7] cm[sup [minus]2]. Using these two now methods of GaAs-on-Si material growth, we made solar cells that are expected to show higher efficiencies than those of previous cells.

  9. Equation of state and phase diagram of Fe-16Si alloy as a candidate...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Equation of state and phase diagram of Fe-16Si alloy as a candidate component of Earths core Citation Details In-Document Search ...

  10. Local environment of Mn in Mn delta-doped Si layers

    SciTech Connect (OSTI)

    Xiao, Q.F.; Kahwaji, S.; Monchesky, T.L.; Gordon, R.A.; Crozier, E.D.

    2009-11-09

    Dilute magnetic semiconductors combine both magnetic ordering and semiconducting behaviour, leading to potential spintronic applications. Silicon containing dilute Mn impurities is a potential dilute magnetic semiconductor. We have grown Mn delta-doped films by deposition of 0.7 of a monolayer of Mn on Si(001) by molecular beam epitaxy and capping the film with Si. The magnetic properties are likely sensitive to the distribution of Mn on substitutional or interstitial sites and the formation of metallic precipitates. We have used polarization-dependent XAFS to examine the local structure. We compare to a thicker MnSi film grown on Si(111) and also examine the influence of lead on the manganese environment when used as a surfactant in the growth process.

  11. Equations of state in the Fe-FeSi system at high pressures and...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Equations of state in the Fe-FeSi system at high pressures and temperatures Citation Details In-Document Search Title: Equations of ...

  12. Vehicle Technologies Office Merit Review 2015: Si Alloy Anode: Sudden Fade Challenge

    Broader source: Energy.gov [DOE]

    Presentation given by 3M at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about Si alloy anode: sudden fade challenge.

  13. U.S. Department of Energy Accident Resistant SiC Clad Nuclear Fuel Development

    Broader source: Energy.gov [DOE]

    A significant effort is being placed on silicon carbide ceramic matrix composite (SiC CMC) nuclear fuel cladding by Light Water Reactor Sustainability (LWRS) Advanced Light Water Reactor Nuclear...

  14. Microporous SiO{sub 2} with huge electric-double-layer capacitance...

    Office of Scientific and Technical Information (OSTI)

    Room-temperature deposited microporous SiOsub 2 dielectric is promising for low-power field-effect transistors on temperature sensitive substrates. Authors: Lu Aixia ; Sun Jia ; ...

  15. Blue photoluminescence enhancement in laser-irradiated 6H-SiC at room temperature

    SciTech Connect (OSTI)

    Wu, Yan; Ji, Lingfei Lin, Zhenyuan; Jiang, Yijian; Zhai, Tianrui

    2014-01-27

    Blue photoluminescence (PL) of 6H-SiC irradiated by an ultraviolet laser can be observed at room temperature in dark condition. PL spectra with Gaussian fitting curve of the irradiated SiC show that blue luminescence band (?440?nm) is more pronounced than other bands. The blue PL enhancement is the combined result of the improved shallow N-donor energy level and the unique surface state with Si nanocrystals and graphene/Si composite due to the effect of photon energy input by the short-wavelength laser irradiation. The study can provide a promising route towards the preparation of well-controlled blue photoluminescence material for light-emitting devices.

  16. Incorporation of Catalytic Compounds in the Porosity of SiC Wall...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Incorporation of Catalytic Compounds in the Porosity of SiC Wall Flow Filters - 4 Way Catalyst and DeNOx Application examples Incorporation of Catalytic Compounds in the Porosity...

  17. GeSi strained nanostructure self-assembly for nano- and opto...

    Office of Scientific and Technical Information (OSTI)

    nanostructure self-assembly for nano- and opto-electronics. Citation Details In-Document Search Title: GeSi strained nanostructure self-assembly for nano- and opto-electronics. ...

  18. Numerical design of SiC bulk crystal growth for electronic applications

    SciTech Connect (OSTI)

    Wejrzanowski, T.; Grybczuk, M.; Kurzydlowski, K. J.; Tymicki, E.

    2014-10-06

    Presented study concerns numerical simulation of Physical Vapor Transport (PVT) growth of bulk Silicon Carbide (SiC) crystals. Silicon Carbide is a wide band gap semiconductor, with numerous applications due to its unique properties. Wider application of SiC is limited by high price and insufficient quality of the product. Those problems can be overcame by optimizing SiC production methods. Experimental optimization of SiC production is expensive because it is time consuming and requires large amounts of energy. Numerical modeling allows to learn more about conditions inside the reactor and helps to optimize the process at much lower cost. In this study several simulations of processes with different reactor geometries were presented along with discussion of reactor geometry influence on obtained monocrystal shape and size.

  19. Tailoring of a metastable material: alfa-FeSi2 thin film

    SciTech Connect (OSTI)

    Cao, Guixin; Singh, David J; Zhang, Xiaoguang; Samolyuk, German D; Qiao, Liang; Parish, Chad M; Ke, Jin; Zhang, Yanwen; Guo, Hangwen; Tang, Siwei; Wang, Wenbin; Yi, Jieyu; Cantoni, Claudia; Siemons, Wolter; Payzant, E Andrew; Biegalski, Michael D; Ward, Thomas Zac; Sales, Brian C; Mandrus, D.; Stocks, George Malcolm; Gai, Zheng

    2015-01-01

    The epitaxially stabilized metallic -FeSi2 thin films on Si(001) were grown using pulsed laser deposition. While the bulk material of -FeSi2 is a high temperature metastable phase and nonmagnetic, the thin film is stabilized at room temperature and shows unusual electronic transport and magnetic properties due to strain modification. The transport renders two different conducting states with a strong crossover at 50 K accompanied by an onset of ferromagnetism as well as a substantial magnetocaloric effect and magnetoresistance. These experimental results are discussed in terms of the unusual electronic structure of -FeSi2 obtained within density functional calculations and Boltzmann transport calculations with and without strain. Our findings provide an example of a tailored material with interesting physics properties for practical applications.

  20. Vehicle Technologies Office Merit Review 2014: Development of SiC Large Tapered Crystal Growth

    Broader source: Energy.gov [DOE]

    Presentation given by NASA at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about development of SiC large tapered crystal...

  1. Formation of quantum spin Hall state on Si surface and energy...

    Office of Scientific and Technical Information (OSTI)

    Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling Citation Details In-Document Search Title: Formation of quantum spin ...

  2. Doped silicon nanocrystals from organic dopant precursor by a SiCl{sub 4}-based high frequency nonthermal plasma

    SciTech Connect (OSTI)

    Zhou, Shu; Ding, Yi; Nozaki, Tomohiro; Pi, Xiaodong

    2014-11-03

    Doped silicon nanocrystals (Si NCs) are of great interest in demanding low-cost nanodevices because of the abundance and nontoxicity of Si. Here, we demonstrate a cost-effective gas phase approach to synthesize phosphorous (P)-doped Si NCs in which the precursors used, i.e., SiCl{sub 4}, trimethyl phosphite (TMP), are both safe and economical. It is found that the TMP-enabled P-doping does not change the crystalline structure of Si NCs. The surface of P-doped Si NCs is terminated by both Cl and H. The Si–H bond density at the surface of P-doped Si NCs is found to be much higher than that of undoped Si NCs. The X-ray photoelectron spectroscopy and electron spin resonance results indicate that P atoms are doped into the substitutional sites of the Si-NC core and electrically active in Si NCs. Unintentional impurities, such as carbon contained in TMP, are not introduced into Si NCs.

  3. Metalorganic chemical vapor deposition and characterization of (Al,Si)O dielectrics for GaN–based devices

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chan, Silvia; Mishra, Umesh K.; Tahhan, Maher; Liu, Xiang; Bisi, David; Gupta, Chirag; Koksaldi, Onur; Li, Haoran; Mates, Tom; DenBaars, Steven P.; et al

    2016-01-20

    In this study, we report on the growth and electrical characterization of (Al,Si)O dielectrics grown by metalorganic chemical vapor deposition (MOCVD) using trimethylaluminum, oxygen, and silane as precursors. The growth rates, refractive indices, and composition of (Al,Si)O films grown on Si(001) were determined from ellipsometry and XPS measurements. Crystallinity and electrical properties of (Al,Si)O films grown in situ on c-plane GaN were characterized using grazing incidence X-ray diffraction and capacitance–voltage with current–voltage measurements, respectively. Si concentration in the films was found to be tunable by varying the trimethylaluminum and/or oxygen precursor flows. The Si incorporation suppressed the formation of crystallinemore » domains, leading to amorphous films that resulted in reduced interfacial trap density, low gate leakage and ultra-low hysteresis in (Al,Si)O/n-GaN MOS-capacitors.« less

  4. Microstructure and Thermoelectric Properties of Mechanically Robust PbTe-Si

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Eutectic Composites | Energy Frontier Research Centers Microstructure and Thermoelectric Properties of Mechanically Robust PbTe-Si Eutectic Composites Home Author: J. R. Sootsman, J. He, V. P. Dravid, S. Ballikaya, D. Vermeulen, C. Uher, M. G. Kanatzidis Year: 2010 Abstract: The microstructure and thermoelectric properties of the PbTe-Si eutectic system are presented in detail. When rapidly quenched from the melt this system yields materials with thermoelectric properties similar to PbTe

  5. Molecular dynamics modeling of atomic displacement cascades in 3C-SiC:

    Office of Scientific and Technical Information (OSTI)

    Comparison of interatomic potentials (Journal Article) | DOE PAGES Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials This content will become publicly available on June 3, 2016 « Prev Next » Title: Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in

  6. GeSi strained nanostructure self-assembly for nano- and opto-electronics.

    Office of Scientific and Technical Information (OSTI)

    (Technical Report) | SciTech Connect GeSi strained nanostructure self-assembly for nano- and opto-electronics. Citation Details In-Document Search Title: GeSi strained nanostructure self-assembly for nano- and opto-electronics. Strain-induced self-assembly during semiconductor heteroepitaxy offers a promising approach to produce quantum nanostructures for nanologic and optoelectronics applications. Our current research direction aims to move beyond self-assembly of the basic quantum dot

  7. Hydrothermal corrosion of SiC in LWR coolant environments in the absence of

    Office of Scientific and Technical Information (OSTI)

    irradiation (Journal Article) | SciTech Connect Journal Article: Hydrothermal corrosion of SiC in LWR coolant environments in the absence of irradiation Citation Details In-Document Search Title: Hydrothermal corrosion of SiC in LWR coolant environments in the absence of irradiation Authors: Terrani, Kurt A [1] ; Yang, Ying [1] ; Kim, Young-Jin [2] ; Rebak, Raul [2] ; Meyer III, Harry M [1] ; Gerczak, Tyler J [1] + Show Author Affiliations ORNL General Electric (GE) Publication Date:

  8. PROJECT PROFILE: Overcoming Bottlenecks to Low-Cost, High-Efficiency Si PV

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Industrially Relevant, Ion Implanted, Interdigitated Back Passivated Contact Cell Development | Department of Energy Overcoming Bottlenecks to Low-Cost, High-Efficiency Si PV and Industrially Relevant, Ion Implanted, Interdigitated Back Passivated Contact Cell Development PROJECT PROFILE: Overcoming Bottlenecks to Low-Cost, High-Efficiency Si PV and Industrially Relevant, Ion Implanted, Interdigitated Back Passivated Contact Cell Development Funding Opportunity: SuNLaMP SunShot

  9. Low Cost SiOx-Graphite and Olivine Materials | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    10 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C. PDF icon es048_zaghib_2010_p.pdf More Documents & Publications Low Cost SiOx-Graphite and High Voltage Spinel Cathode Low Cost SiOx-Graphite and Olivine Materials FY 2012 Annual Progress Report for Energy Storage R&D

  10. Manufacturing Metrology for c-Si Module Reliability/Durabiltiy | Department

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of Energy Manufacturing Metrology for c-Si Module Reliability/Durabiltiy Manufacturing Metrology for c-Si Module Reliability/Durabiltiy Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PDF icon pvmrw13_ps1_fsec_rogers.pdf More Documents & Publications Agenda for the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado SunShot Vision Study: February 2012 (Book), SunShot, Energy Efficiency & Renewable Energy (EERE) EXPERIENCES

  11. HD Applications of Significantly Downsized SI Engines Using Alcohol DI for

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Knock Avoidance | Department of Energy Applications of Significantly Downsized SI Engines Using Alcohol DI for Knock Avoidance HD Applications of Significantly Downsized SI Engines Using Alcohol DI for Knock Avoidance Direct injection of a second fuel (ethanol or methanol) is explored as a means of avoiding knock in turbocharged, high-compression ratio spark-ignited engines that could replace diesels in certain vocational applications. PDF icon deer08_blumberg.pdf More Documents &

  12. Phase relations in the Fe–FeSi system at high pressures and temperatures

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Journal Article: Phase relations in the Fe–FeSi system at high pressures and temperatures Citation Details In-Document Search Title: Phase relations in the Fe–FeSi system at high pressures and temperatures Authors: Fischer, Rebecca A. ; Campbell, Andrew J. ; Reaman, Daniel M. ; Miller, Noah A. ; Heinz, Dion L. ; Dera, Przymyslaw ; Prakapenka, Vitali B. [1] ; UC) [2] + Show Author Affiliations (Maryland) ( Publication Date: 2013-06-12 OSTI Identifier:

  13. Effect of dynamics on the elastic softening of vacancies in Si (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Effect of dynamics on the elastic softening of vacancies in Si Citation Details In-Document Search Title: Effect of dynamics on the elastic softening of vacancies in Si Recently, elastic softening at temperatures below 20 K has been observed in nondoped floating zone silicon. From the experimental analysis, it has been suggested that this softening is caused by an intrinsic vacancy defect through the Jahn-Teller (JT) effect. We have theoretically studied the

  14. Electrostatic Transfor of Patterned Epitaxial Graphene from SiC (001) to

    Office of Scientific and Technical Information (OSTI)

    Glass. (Journal Article) | SciTech Connect Electrostatic Transfor of Patterned Epitaxial Graphene from SiC (001) to Glass. Citation Details In-Document Search Title: Electrostatic Transfor of Patterned Epitaxial Graphene from SiC (001) to Glass. Abstract not provided. Authors: Biedermann, Laura ; Beechem Iii, Thomas Edwin ; Ohta, Taisuke ; Howell, Stephen Wayne ; Ross, Anthony J. III Publication Date: 2010-06-01 OSTI Identifier: 1142067 Report Number(s): SAND2010-4200J Journal ID: ISSN

  15. Fabrication and Hydrothermal Corrosion of NITE-SiC with Various Sintering

    Office of Scientific and Technical Information (OSTI)

    Additives (Conference) | SciTech Connect Conference: Fabrication and Hydrothermal Corrosion of NITE-SiC with Various Sintering Additives Citation Details In-Document Search Title: Fabrication and Hydrothermal Corrosion of NITE-SiC with Various Sintering Additives Authors: Terrani, Kurt A [1] ; Katoh, Yutai [1] ; Parish, Chad M [1] ; Kim, Young-Jin [2] + Show Author Affiliations ORNL General Electric (GE) Publication Date: 2016-01-01 OSTI Identifier: 1237151 DOE Contract Number:

  16. Equations of state in the Fe-FeSi system at high pressures and temperatures

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Equations of state in the Fe-FeSi system at high pressures and temperatures Citation Details In-Document Search Title: Equations of state in the Fe-FeSi system at high pressures and temperatures Authors: Fischer, Rebecca A. ; Campbell, Andrew J. ; Caracas, Razvan ; Reaman, Daniel M. ; Heinz, Dion L. ; Dera, Przemyslaw ; Prakapenka, Vitali B. [1] ; UC) [2] ; Claude-Bernard) [2] + Show Author Affiliations

  17. Formation of quantum spin Hall state on Si surface and energy gap scaling

    Office of Scientific and Technical Information (OSTI)

    with strength of spin orbit coupling (Journal Article) | DOE PAGES DOE PAGES Search Results Accepted Manuscript: Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling Title: Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling For potential applications in spintronics and quantum computing, it is desirable to place a quantum spin Hall insulator [i.e., a 2D topological insulator

  18. The thermal equation of state of (Mg, Fe)SiO[subscript 3] bridgmanite

    Office of Scientific and Technical Information (OSTI)

    (perovskite) and implications for lower mantle structures (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: The thermal equation of state of (Mg, Fe)SiO[subscript 3] bridgmanite (perovskite) and implications for lower mantle structures Citation Details In-Document Search Title: The thermal equation of state of (Mg, Fe)SiO[subscript 3] bridgmanite (perovskite) and implications for lower mantle structures Authors: Wolf, Aaron S. ; Jackson, Jennifer M. ; Dera,

  19. Ultrathin nanosheets of CrSiTe3: A semiconducting two-dimensional

    Office of Scientific and Technical Information (OSTI)

    ferromagnetic material (Journal Article) | SciTech Connect Ultrathin nanosheets of CrSiTe3: A semiconducting two-dimensional ferromagnetic material Citation Details In-Document Search This content will become publicly available on November 27, 2016 Title: Ultrathin nanosheets of CrSiTe3: A semiconducting two-dimensional ferromagnetic material Finite range ferromagnetism and antiferromagnetism in two-dimensional (2D) systems within an isotropic Heisenberg model at non-zero temperature were

  20. Nano-/micro metallic wire synthesis on Si substrate and their characterization

    SciTech Connect (OSTI)

    Kaur, Jaskiran Kaur, Harmanmeet Singh, Surinder; Kanjilal, Dinakar; Chakarvarti, Shiv Kumar

    2014-04-24

    Nano-/micro wires of copper are grown on semiconducting Si substrate using the template method. It involves the irradiation of 8 um thick polymeric layer coated on Si with150 MeV Ni ion beam at a fluence of 2E8. Later, by using the simple technique of electrodeposition, copper nano-/micro wires were grown via template synthesis. Synthesized wires were morphologically characterized using SEM and electrical characterization was carried out by finding I-V plot.

  1. Development of High-Efficiency Clean Combustion Engines Designs for SI and

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    CI Engines | Department of Energy High-Efficiency Clean Combustion Engines Designs for SI and CI Engines Development of High-Efficiency Clean Combustion Engines Designs for SI and CI Engines 2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C. PDF icon ace036_patton_2010_o.pdf More Documents & Publications High Efficiency Clean Combustion Engine Designs for Gasoline and Diesel Engines High Efficiency Clean

  2. Development of an SI DI Ethanol Optimized Flex Fuel Engine Using Advanced

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Valvetrain | Department of Energy an SI DI Ethanol Optimized Flex Fuel Engine Using Advanced Valvetrain Development of an SI DI Ethanol Optimized Flex Fuel Engine Using Advanced Valvetrain Presentation given at the 16th Directions in Engine-Efficiency and Emissions Research (DEER) Conference in Detroit, MI, September 27-30, 2010. PDF icon deer10_moore.pdf More Documents & Publications E85 Optimized Engine through Boosting, Spray Optimized GDi, VCR and Variable Valvetrain Flex Fuel

  3. Spillover-Assisted Hydrogen Evolution at Si-based Metal-Oxide-Semiconductor

    Office of Scientific and Technical Information (OSTI)

    Photoelectrodes. (Journal Article) | SciTech Connect Spillover-Assisted Hydrogen Evolution at Si-based Metal-Oxide-Semiconductor Photoelectrodes. Citation Details In-Document Search Title: Spillover-Assisted Hydrogen Evolution at Si-based Metal-Oxide-Semiconductor Photoelectrodes. Authors: Talin, Albert Alec ; Esposito, Daniel V. ; Levin, Igor ; Moffat, Thomas P. Publication Date: 2012-12-01 OSTI Identifier: 1063415 Report Number(s): SAND2012-10868J DOE Contract Number: AC04-94AL85000

  4. Strain and lattice orientation distribution in SiN/Ge complementary

    Office of Scientific and Technical Information (OSTI)

    metal-oxide-semiconductor compatible light emitting microstructures by quick x-ray nano-diffraction microscopy (Journal Article) | SciTech Connect Strain and lattice orientation distribution in SiN/Ge complementary metal-oxide-semiconductor compatible light emitting microstructures by quick x-ray nano-diffraction microscopy Citation Details In-Document Search Title: Strain and lattice orientation distribution in SiN/Ge complementary metal-oxide-semiconductor compatible light emitting

  5. Theoretical investigations of defects in a Si-based digital ferromagnetic

    Office of Scientific and Technical Information (OSTI)

    heterostructure - a spintronic material (Journal Article) | SciTech Connect Journal Article: Theoretical investigations of defects in a Si-based digital ferromagnetic heterostructure - a spintronic material Citation Details In-Document Search Title: Theoretical investigations of defects in a Si-based digital ferromagnetic heterostructure - a spintronic material Authors: Fong, C Y ; Shauhgnessy, M ; Snow, R ; Yang, L H Publication Date: 2010-09-17 OSTI Identifier: 1124958 Report Number(s):

  6. Radiation damage of GaAs thin-film solar cells on Si substrates

    SciTech Connect (OSTI)

    Itoh, Y.; Yamaguchi, M.; Nishioka, T.; Yamamoto, A.

    1987-01-15

    1-MeV electron irradiation damages in GaAs thin-film solar cells on Si substrates are examined for the first time. Damage constant for minority-carrier diffusion length in GaAs heteroepitaxial films on Si substrates is found to be the same as that in GaAs homoepitaxial films on GaAs substrates. This agreement suggests that GaAs/Si has the same defect introduction rate with radiation as GaAs/GaAs. The degradation of GaAs solar cells on Si with electron irradiation is less than that of GaAs solar cells on GaAs, because in the present, GaAs films on Si substrates have lower minority-carrier diffusion length compared to GaAs films on GaAs and these films are insensitive to radiation. The p/sup +/-p/sup +/-n AlGaAs-GaAs heteroface solar cell with junction depth of about 0.3 ..mu..m is concluded to be useful for a high-efficiency and radiation-resistant solar cell fabricated on a Si substrate.

  7. Electronic band structure and Kondo coupling in YbRh2Si2

    SciTech Connect (OSTI)

    Wigger, G.A.

    2010-04-15

    The electronic band structure of YbRh2Si2 is calculated in a relativistic framework including correlation corrections and magnetization of the Yb ion and compared to detailed angle-resolved photoemission spectra. The photoemission spectra for LuRh2Si2 are used as reference to identify electronic bands with no f symmetry. The calculated band structure manifests a 4f13 spin-polarized configuration leaving the unoccupied state at 1.4eV above the Fermi energy. At the band theory level, the 4f bands are located far below the Fermi level and the anisotropic Coulomb interaction within the 4f shell spreads the multilevel into broader 4f complexes below -2.5eV . The photoemission spectra obtained on YbRh2Si2 show a clear f -multilevel splitting into j=7/2 and 5/2 excitations. The interaction of the 4f7/2 levels close to the Fermi energy with two conduction bands shows visible hybridization gaps of 45 and 80meV, respectively. We discuss the origin of these excitations and provide an analysis according to Anderson's single-impurity model with parameters suggested by the band-structure calculation and the photoemission spectra. Both experiment and theory indicate nearly identical Fermi surfaces for LuRh2Si2 and YbRh2Si2 . The valency of Yb in YbRh2Si2 is estimated to be close to +3.

  8. Deep levels generated by thermal oxidation in p-type 4H-SiC

    SciTech Connect (OSTI)

    Kawahara, Koutarou; Suda, Jun; Kimoto, Tsunenobu

    2013-01-21

    Thermal oxidation is an effective method to reduce deep levels, especially the Z{sub 1/2}-center (E{sub C}-0.67 eV), which strongly suppresses carrier lifetimes in n-type 4H-SiC epilayers. The oxidation, however, simultaneously generates other deep levels, HK0 (E{sub V}+0.79 eV) and HK2 (E{sub V}+0.98 eV) centers, within the lower half of the bandgap of SiC, where the HK0 center is a dominant deep level with a concentration of about 1 Multiplication-Sign 10{sup 13} cm{sup -3} after oxidation. By comparing deep levels observed in three sets of p-type 4H-SiC: oxidized, electron-irradiated, and C{sup +}- or Si{sup +}-implanted samples, we find that the HK0 and HK2 centers are complexes including carbon interstitials such as the di-carbon interstitial or di-carbon antisite. Other defects observed in p-type 4H-SiC after electron irradiation or after C{sup +}/Si{sup +} implantation are also studied.

  9. A SiC MOSFET Based Inverter for Wireless Power Transfer Applications

    SciTech Connect (OSTI)

    Onar, Omer C; Chinthavali, Madhu Sudhan; Campbell, Steven L; Ning, Puqi; White, Cliff P; Miller , John M.

    2014-01-01

    In a wireless power transfer (WPT) system, efficiency of the power conversion stages is crucial so that the WPT technology can compete with the conventional conductive charging systems. Since there are 5 or 6 power conversion stages, each stage needs to be as efficient as possible. SiC inverters are crucial in this case; they can handle high frequency operation and they can operate at relatively higher temperatures resulting in reduces cost and size for the cooling components. This study presents the detailed power module design, development, and fabrication of a SiC inverter. The proposed inverter has been tested at three center frequencies that are considered for the WPT standardization. Performance of the inverter at the same target power transfer level is analyzed along with the other system components. In addition, another SiC inverter has been built in authors laboratory by using the ORNL designed and developed SiC modules. It is shown that the inverter with ORNL packaged SiC modules performs simular to that of the inverter having commercially available SiC modules.

  10. U.S. Department of Energy Accident Resistant SiC Clad Nuclear Fuel Development

    SciTech Connect (OSTI)

    George W. Griffith

    2011-10-01

    A significant effort is being placed on silicon carbide ceramic matrix composite (SiC CMC) nuclear fuel cladding by Light Water Reactor Sustainability (LWRS) Advanced Light Water Reactor Nuclear Fuels Pathway. The intent of this work is to invest in a high-risk, high-reward technology that can be introduced in a relatively short time. The LWRS goal is to demonstrate successful advanced fuels technology that suitable for commercial development to support nuclear relicensing. Ceramic matrix composites are an established non-nuclear technology that utilizes ceramic fibers embedded in a ceramic matrix. A thin interfacial layer between the fibers and the matrix allows for ductile behavior. The SiC CMC has relatively high strength at high reactor accident temperatures when compared to metallic cladding. SiC also has a very low chemical reactivity and doesn't react exothermically with the reactor cooling water. The radiation behavior of SiC has also been studied extensively as structural fusion system components. The SiC CMC technology is in the early stages of development and will need to mature before confidence in the developed designs can created. The advanced SiC CMC materials do offer the potential for greatly improved safety because of their high temperature strength, chemical stability and reduced hydrogen generation.

  11. Real time synchrotron X-ray observations of solidification in hypoeutectic AlSi alloys

    SciTech Connect (OSTI)

    Nogita, Kazuhiro [Nihon Superior Centre for the Manufacture of Electronic Materials, The University of Queensland, Brisbane, QLD 4072 (Australia); School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia); Yasuda, Hideyuki [Department of Adaptive Machine Systems, Osaka University, Suita, Osaka, 565-0871 (Japan); Prasad, Arvind [School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia); McDonald, Stuart D., E-mail: s.mcdonald1@uq.edu.au [Nihon Superior Centre for the Manufacture of Electronic Materials, The University of Queensland, Brisbane, QLD 4072 (Australia); School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia); Nagira, Tomoya; Nakatsuka, Noriaki [Department of Adaptive Machine Systems, Osaka University, Suita, Osaka, 565-0871 (Japan); Uesugi, Kentaro [Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo, 679-5198 (Japan); StJohn, David H. [School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia)

    2013-11-15

    This paper demonstrates how recent advances in synchrotron technology have allowed for the real-time X-ray imaging of solidification in AlSi alloys, despite the small difference in atomic number of these elements. The experiments performed at the SPring-8 synchrotron, involved imaging the solidification of Al1wt.%Si and Al4wt.%Si alloys under a low-temperature gradient and a cooling rate of around 0.3 C/s. The nucleation and growth of the primary aluminum grains as well as the onset of eutectic solidification were clearly observed. In the alloys containing Al4wt.%Si, contrast was sufficient to characterize the nucleation rate and growth velocity of the aluminum grains. The importance of improving observation of solidification in the AlSi system by increasing the time resolution during critical events is discussed. - Highlights: A synchrotron technique was used to observe solidification of Al-Si alloys. Nucleation, coarsening, and the onset of eutectic solidification were observed. Images captured are suitable for quantitative analysis. The resolution that was obtained should be possible for most aluminum alloys.

  12. Manufacturing of SiCp Reinforced Magnesium Composite Tubes by Hot Extrusion Processes

    SciTech Connect (OSTI)

    Hwang, Yeong-Maw [National Sun Yat-Sen University-Department of Mechanical and Electro-mechanical Engineering, No.70, Lien-Hai Rd., Kaohsiung, Taiwan (China); Huang, Song-Jeng; Huang, Yu-San [National Chung Cheng University-Department of Mechanical Engineering, 168 University Rd. Ming-Hsiung, ChiaYi, Taiwan (China)

    2011-05-04

    Magnesium alloys have higher specific strength compared with other metals, such as aluminum, copper and steel. Nevertheless, their ductility is still not good for further metal forming and their strength is not large enough for real structure applications. The aim of this paper is to develop magnesium alloy composite tubes reinforced with SiC particulates by the stir-casting method and hot extrusion processes. At first, AZ61/SiCp composite ingots reinforced with 5 wt% SiC particulates are fabricated by the melt-stirring technique. Then, finite element simulations are conducted to analyze the plastic flow of magnesium alloy AZ61 within the die and the temperature distribution of the products. AZ61/SiCp composite tubes are manufactured by hot extrusion using a specially designed die-set for obtaining uniform thickness distribution tubes. Finally, the mechanical properties of the reinforced AZ61/SiCp composite and Mg alloy AZ61 tubes are compared with those of the billets to manifest the advantages of extrusion processes and reinforcement of SiC particulates. The microstructures of the billet and extruded tubes are also observed. Through the improvement of the strength of the tube product, its life cycle can be extended and the energy consumption can be reduced, and eventually the environmental sustainability is achieved.

  13. Formation of PtSi Schottky barrier MOSFETs using plasma etching

    SciTech Connect (OSTI)

    Woo, Young Min; Hwang, Wan Sik; Yoo, Won Jong

    2015-03-15

    PtSi Schottky barrier (SB) MOSFETs were fabricated and their device performance was characterized. PtSi was selected instead of NiSi to form the p-type SB junction since such a configuration would be easy to fabricate through SF{sub 6} based plasma etching. The addition of He-O{sub 2} in SF{sub 6} decreases the etching rate of PtSi while the etching rate of Pt remains unchanged. The retardation in the etching rate of PtSi in He-O{sub 2}/SF{sub 6} is attributed to the formation of a metal oxide on the etched PtSi surface, as evidenced by the x-ray photoelectron spectroscopy results. Optical emission spectroscopy was conducted to establish the endpoint where the wavelength from the feed gas was traced instead of tracing the etching by-products since the by-products have little association with the plasma reaction. The I{sub DS}V{sub DS} curves at various V{sub G}V{sub TH} indicate that plasma etching resulted in the successful removal of the Pt on the sidewall region, with negligible damage to the S/D area.

  14. Chemical pressure tuning of URu?Si? via isoelectronic substitution of Ru with Fe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Das, Pinaki; Kanchanavatee, N.; Helton, J. S.; Huang, K.; Baumbach, R. E.; Bauer, E. D.; White, B. D.; Burnett, V. W.; Maple, M. B.; Lynn, J. W.; et al

    2015-02-01

    We have used specific heat and neutron diffraction measurements on single crystals of URu2xFexSi? for Fe concentrations x ? 0.7 to establish that chemical substitution of Ru with Fe acts as chemical pressure Pch as previously proposed by Kanchanavatee et al. [Phys. Rev. B 84, 245122 (2011)] based on bulk measurements on polycrystalline samples. Notably, neutron diffraction reveals a sharp increase of the uranium magnetic moment at x = 0.1, reminiscent of the behavior at the hidden order to large moment antiferromagnetic (LMAFM) phase transition observed at a pressure Px ? 0.5-0.7 GPa in URu?Si?. Using the unit cell volumemoredetermined from our measurements and an isothermal compressibility ?T = 5.210? GPa? for URu?Si?, we determine the chemical pressure Pch in URu2?xFexSi? as a function of x. The resulting temperature T-chemical pressure Pch phase diagram for URu2?xFexSi? is in agreement with the established temperature T-external pressure P phase diagram of URu?Si?.less

  15. Oxidation-resistant, solution-processed plasmonic Ni nanochain-SiO{sub x} (x?

    SciTech Connect (OSTI)

    Yu, Xiaobai; Wang, Xiaoxin; Liu, Jifeng; Zhang, Qinglin; Li, Juchuan

    2014-08-21

    Metal oxidation at high temperatures has long been a challenge in cermet solar thermal absorbers, which impedes the development of atmospherically stable, high-temperature, high-performance concentrated solar power (CSP) systems. In this work, we demonstrate solution-processed Ni nanochain-SiO{sub x} (x?SiO{sub 2} selective solar thermal absorbers that exhibit a strong anti-oxidation behavior up to 600?C in air. The thermal stability is far superior to previously reported Ni nanoparticle-Al{sub 2}O{sub 3} selective solar thermal absorbers, which readily oxidize at 450?C. The SiO{sub x} (x?SiO{sub 2} matrices are derived from hydrogen silsesquioxane and tetraethyl orthosilicate precursors, respectively, which comprise Si-O cage-like structures and Si-O networks. Fourier transform infrared spectroscopy shows that the dissociation of Si-O cage-like structures and Si-O networks at high temperatures have enabled the formation of new bonds at the Ni/SiO{sub x} interface to passivate the surface of Ni nanoparticles and prevent oxidation. X-ray photoelectron spectroscopy and Raman spectroscopy demonstrate that the excess Si in the SiO{sub x} (x?SiO{sub x} (x?SiO{sub 2} systems. This oxidation-resistant Ni nanochain-SiO{sub x} (x?

  16. K*(892)⁰ and K̄*(892)⁰ production in central Pb + Pb, Si + Si, C + C, and inelastic p + p collisions at 158A GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Anticic, T.; Baatar, B.; Barna, D.; Bartke, J.; Beck, H.; Betev, L.; Białkowska, H.; Blume, C.; Bogusz, M.; Boimska, B.; et al

    2011-12-13

    Production of the K*(892)0 and K̄*(892)⁰ resonances was studied via their K⁺π⁻ and K⁻π⁺ decay modes in central Pb+Pb, Si+Si, C+C, and inelastic p+p collisions at 158A GeV(√(sNN)=17.3 GeV) with the NA49 detector at the CERN SPS. Transverse momentum and rapidity distributions were measured and total yields were estimated. The yield of K* exceeds that of K̄* by about a factor of two in nucleus-nucleus reactions. The total yield ratios ⟨K*⟩/⟨K+⟩ and ⟨K̄*⟩/⟨K-⟩ are strongly suppressed in central Pb+Pb compared to p+p, C+C, and Si+Si collisions, in agreement with the expected attenuation of these short-lived resonance states in the hadronicmore » phase of the expanding fireball. The UrQMD model, although incorporating such a scenario, does not provide a quantitative description of the experimental results. The statistical hadron gas model assuming the same freeze-out parameters for stable hadrons and resonances overestimates the ⟨K*⟩/⟨K⟩ ratios in central Pb+Pb collisions by about a factor of 2.5.« less

  17. Synthesis, structure and chemical bonding of CaFe{sub 2?x}Rh{sub x}Si{sub 2} (x=0, 1.32, and 2) and SrCo{sub 2}Si{sub 2}

    SciTech Connect (OSTI)

    Hlukhyy, Viktor Hoffmann, Andrea V.; Fssler, Thomas F.

    2013-07-15

    The finding of superconductivity in Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2} put the attention on the investigation of compounds that crystallize with ThCr{sub 2}Si{sub 2} structure type such as AT{sub 2}X{sub 2} (A=alkali/alkaline earth/rare earth element; T=transition metal and X=element of the 1315th group). In this context the silicides CaFe{sub 2}Si{sub 2}, CaFe{sub 0.68(6)}Rh{sub 1.32(6)}Si{sub 2}, CaRh{sub 2}Si{sub 2} and SrCo{sub 2}Si{sub 2} have been synthesized by reaction of the elements under an argon atmosphere. Single crystals were obtained by special heat treatment in welded niobium/tantalum ampoules. The compounds were investigated by means of powder and single crystal X-ray diffraction. All compounds crystallize in the ThCr{sub 2}Si{sub 2}-type structure with space group I4/mmm (No. 139): a=3.939(1) , c=10.185(1) , R{sub 1}=0.045, 85 F{sup 2} values, 8 variable parameters for CaFe{sub 2}Si{sub 2}; a=4.0590(2) , c=9.9390(8) , R{sub 1}=0.030, 90 F{sup 2} values, 10 variable parameters for CaFe{sub 0.68(6)}Rh{sub 1.32(6)}Si{sub 2}; a=4.0695(1) , c=9.9841(3) , R{sub 1}=0.031, 114 F{sup 2} values, 9 variable parameters for CaRh{sub 2}Si{sub 2}; and a=3.974(1) , c=10.395(1) , R{sub 1}=0.036, 95 F{sup 2} values, 8 variable parameters for SrCo{sub 2}Si{sub 2}. The structure of SrCo{sub 2}Si{sub 2} contains isolated [Co{sub 2}Si{sub 2}]{sup 2?} 2D-layers in the ab-plane whereas in CaFe{sub 2?x}Rh{sub x}Si{sub 2} the [T{sub 2}Si{sub 2}] layers (T=Fe and Rh) are interconnected along the c-axis via Si3Si bonds resulting in a three-dimentional (3D) [T{sub 2}Si{sub 2}]{sup 2?} polyanions and therefore belong to the so-called collapsed form of the ThCr{sub 2}Si{sub 2}-type structure. The SrCo{sub 2}Si{sub 2} and CaRh{sub 2}Si{sub 2} are isoelectronic to the parent 122 ironpnictide superconductors AeFe{sub 2}As{sub 2} (Ae=alkaline earth elements), whereas CaFe{sub 2}Si{sub 2} is a full substituted variant (As/Si) of CaFe{sub 2}As{sub 2}. The crystal chemistry and chemical bonding in the title compounds are discussed in terms of LMTO band structure calculations and a topological analysis using the Electron Localization Function (ELF). - Graphical abstract: The SrCo{sub 2}Si{sub 2} and CaFe{sub 2?x}Rh{sub x}Si{sub 2} (x==0, 1.32, and 2) crystallize in the ThCr{sub 2}Si{sub 2}-type. The structure of SrCo{sub 2}Si{sub 2} contains isolated [Co{sub 2}Si{sub 2}]{sup 2?} layers in the ab-plane, whereas the [T{sub 2}Si{sub 2}] layers in CaFe{sub 2?x}Rh{sub x}Si{sub 2} are interconnected along the c-axis via Si3Si bonds resulting in a [T{sub 2}Si{sub 2}]{sup 2?} network. - Highlights: Synthesis and structure of ternary silicides SrCo{sub 2}Si{sub 2} and CaFe{sub 2?x}Rh{sub x}Si{sub 2} (x=0, 1.32, and 2). The SrCo{sub 2}Si{sub 2} and CaRh{sub 2}Si{sub 2} are isoelectronic to the parent 122 ironpnictide superconductors AeFe{sub 2}As{sub 2}. CaFe{sub 2}Si{sub 2} is a full substituted variant (As/Si) of superconductor CaFe{sub 2}As{sub 2}. The title compounds demonstrate the tunable Si3Si distances.

  18. Computer Aided Multi-scale Design of SiC-Si3N4 Nanoceramic Composites for High-Temperature Structural Applications

    SciTech Connect (OSTI)

    Vikas Tomer; John Renaud

    2010-08-31

    It is estimated that by using better and improved high temperature structural materials, the power generation efficiency of the power plants can be increased by 15% resulting in significant cost savings. One such promising material system for future high-temperature structural applications in power plants is Silicon Carbide-Silicon Nitride (SiC-Si{sub 3}N{sub 4}) nanoceramic matrix composites. The described research work focuses on multiscale simulation-based design of these SiC-Si{sub 3}N{sub 4} nanoceramic matrix composites. There were two primary objectives of the research: (1) Development of a multiscale simulation tool and corresponding multiscale analyses of the high-temperature creep and fracture resistance properties of the SiC-Si{sub 3}N{sub 4} nanocomposites at nano-, meso- and continuum length- and timescales; and (2) Development of a simulation-based robust design optimization methodology for application to the multiscale simulations to predict the range of the most suitable phase morphologies for the desired high-temperature properties of the SiC-Si{sub 3}N{sub 4} nanocomposites. The multiscale simulation tool is based on a combination of molecular dynamics (MD), cohesive finite element method (CFEM), and continuum level modeling for characterizing time-dependent material deformation behavior. The material simulation tool is incorporated in a variable fidelity model management based design optimization framework. Material modeling includes development of an experimental verification framework. Using material models based on multiscaling, it was found using molecular simulations that clustering of the SiC particles near Si{sub 3}N{sub 4} grain boundaries leads to significant nanocomposite strengthening and significant rise in fracture resistance. It was found that a control of grain boundary thicknesses by dispersing non-stoichiometric carbide or nitride phases can lead to reduction in strength however significant rise in fracture strength. The temperature dependent strength and microstructural stability was also significantly depended upon the dispersion of new phases at grain boundaries. The material design framework incorporates high temperature creep and mechanical strength data in order to develop a collaborative multiscale framework of morphology optimization. The work also incorporates a computer aided material design dataset development procedure where a systematic dataset on material properties and morphology correlation could be obtained depending upon a material processing scientist's requirements. Two different aspects covered under this requirement are: (1) performing morphology related analyses at the nanoscale and at the microscale to develop a multiscale material design and analyses capability; (2) linking material behavior analyses with the developed design tool to form a set of material design problems that illustrate the range of material design dataset development that could be performed. Overall, a software based methodology to design microstructure of particle based ceramic nanocomposites has been developed. This methodology has been shown to predict changes in phase morphologies required for achieving optimal balance of conflicting properties such as minimal creep strain rate and high fracture strength at high temperatures. The methodology incorporates complex material models including atomistic approaches. The methodology will be useful to design materials for high temperature applications including those of interest to DoE while significantly reducing cost of expensive experiments.

  19. Hydrogen interaction kinetics of Ge dangling bonds at the Si{sub 0.25}Ge{sub 0.75}/SiO{sub 2} interface

    SciTech Connect (OSTI)

    Stesmans, A. Nguyen Hoang, T.; Afanas'ev, V. V.

    2014-07-28

    The hydrogen interaction kinetics of the GeP{sub b1} defect, previously identified by electron spin resonance (ESR) as an interfacial Ge dangling bond (DB) defect occurring in densities ?7??10{sup 12}?cm{sup ?2} at the SiGe/SiO{sub 2} interfaces of condensation grown (100)Si/a-SiO{sub 2}/Ge{sub 0.75}Si{sub 0.25}/a-SiO{sub 2} structures, has been studied as function of temperature. This has been carried out, both in the isothermal and isochronal mode, through defect monitoring by capacitance-voltage measurements in conjunction with ESR probing, where it has previously been demonstrated the defects to operate as negative charge traps. The work entails a full interaction cycle study, comprised of analysis of both defect passivation (pictured as GeP{sub b1}-H formation) in molecular hydrogen (?1?atm) and reactivation (GeP{sub b1}-H dissociation) in vacuum. It is found that both processes can be suitably described separately by the generalized simple thermal (GST) model, embodying a first order interaction kinetics description based on the basic chemical reactions GeP{sub b1}?+?H{sub 2}???GeP{sub b1}H?+?H and GeP{sub b1}H???GeP{sub b1}?+?H, which are found to be characterized by the average activation energies E{sub f}?=?1.44??0.04?eV and E{sub d}?=?2.23??0.04?eV, and attendant, assumedly Gaussian, spreads ?E{sub f}?=?0.20??0.02?eV and ?E{sub d}?=?0.15??0.02?eV, respectively. The substantial spreads refer to enhanced interfacial disorder. Combination of the separately inferred kinetic parameters for passivation and dissociation results in the unified realistic GST description that incorporates the simultaneous competing action of passivation and dissociation, and which is found to excellently account for the full cycle data. For process times t{sub a}???35?min, it is found that even for the optimum treatment temperature ?380?C, only ?60% of the GeP{sub b1} system can be electrically silenced, still far remote from device grade level. This ineffectiveness is concluded, for the major part, to be a direct consequence of the excessive spreads in the activation energies, ?23 times larger than for the Si DB P{sub b} defects at the standard thermal (111)Si/SiO{sub 2} interface which may be easily passivated to device grade levels, strengthened by the reduced difference between the average E{sub f} and E{sub d} values. Exploring the guidelines of the GST model indicates that passivation can be improved by decreasing T{sub an} and attendant enlarging of t{sub a}, however, at best still leaving ?2% defects unpassivated even for unrealistically extended anneal times. The average dissociation energy E{sub d}???2.23?eV, concluded as representing the GeP{sub b1}-H bond strength, is found to be smaller than the SiP{sub b}-H one, characterized by E{sub d}???2.83?eV. An energy deficiency is encountered regarding the energy sum rule inherent to the GST-model, the origin of which is substantiated to lie with a more complex nature of the forward passivation process than basically depicted in the GST model. The results are discussed within the context of theoretical considerations on the passivation of interfacial Ge DBs by hydrogen.

  20. Charge transfer of single laser crystallized intrinsic and phosphorus-doped Si-nanocrystals visualized by Kelvin probe force microscopy

    SciTech Connect (OSTI)

    Xu, Jie; Xu, Jun Lu, Peng; Shan, Dan; Li, Wei; Chen, Kunji

    2014-10-07

    Isolated intrinsic and phosphorus doped (P-doped) Si-nanocrystals (Si-NCs) on n- and p-Si substrates are fabricated by excimer laser crystallization techniques. The formation of Si-NCs is confirmed by atomic force microscopy (AFM) and conductive AFM measurements. Kelvin probe force microscopy (KPFM) is then carried out to visualize the trapped charges in a single Si-NC dot which derives from the charge transfer between Si-NCs and Si substrates due to their different Fermi levels. The laser crystallized P-doped Si-NCs have a similar Fermi level around the mid-gap to the intrinsic counterparts, which might be caused by the inactivated impurity atoms or the surface states-related Fermi level pinning. A clear rise of the Fermi level in P-doped Si-NCs is observed after a short time thermal annealing treatment, indicating the activation of dopants in Si-NCs. Moreover, the surface charge quantity can be estimated using a simple parallel plate capacitor model for a quantitative understanding of the KPFM results at the nanoscale.

  1. Stability of SiC-Matrix Microencapsulated Fuel Constituents at Relevant LWR Conditions

    SciTech Connect (OSTI)

    Terrani, Kurt A; Katoh, Yutai; Leonard, Keith J; Perez-Bergquist, Alex G; Silva, Chinthaka M; Snead, Lance Lewis

    2014-01-01

    This paper addresses certain key feasibility issues facing the application of SiC-matrix microencapsulated fuels for light water reactor application. Issues addressed are the irradiation stability of the SiC-based nano-powder ceramic matrix under LWR-relevant irradiation conditions, the presence or extent of reaction of the SiC matrix with zirconium-based cladding, the stability of the inner and outer pyrolytic graphite layers of the microencapsulated (TRISO) particle at this uncharacteristically low irradiation temperature, and the state of the particle-matrix interface following irradiation which could possibly effect thermal transport. In the process of determining these feasibility issues microstructural evolution and change in dimension and thermal conductivity was studied. As a general finding the SiC matrix was found to be quite stable with behavior similar to that of CVD SiC. In magnitude the irradiation-induced swelling of the matrix material was slightly higher and irradiation-degraded thermal conductivity was slightly lower as compared to CVD SiC. No significant reaction of this SiC-based nano-powder ceramic matrix material with Zircaloy was observed. Irradiation of the TRISO in the 320-360 C range to a maximum dose of 7.7 1025 n/m2 (E > 0.1 MeV) did not have significant negative impact on the constituent layers of the TRISO fuel. At the highest dose studied layer structure and interface integrity remained essentially unchanged with good apparent thermal transport through the microsphere to the surrounding matrix.

  2. The Effects of Nitrogen on the Interface State Density Near the Conduction Band Edge in 4H and 6H-SiC

    SciTech Connect (OSTI)

    Chung, G.Y.; Tin, C.C.; Isaacs-Smith, T.; Williams, J.R.; McDonald, K.; DiVentra, M.; Pantelides, S.T.; Feldman, L.C.; Weller, R.A.; Holland, O.W.

    2000-06-12

    Results are reported for the passivation of interface states near the conduction band edge in SiO{sub 2}/SiC MOS capacitors using post-oxidation anneals in nitric oxide, ammonia and forming gas (N{sub 2}5%H{sub 2}). Anneals in nitric oxide and ammonia reduce the interface state density significantly for 4H-SiC, while forming gas anneals are largely ineffective. Results suggest that interface states in SiO{sub 2}/SiC and SiO{sub 2}/SiC have different origins, and a model is described for interface state passivation by nitrogen in the SiO{sub 2}/SiC system. The peak inversion channel mobility measured for lateral 4H-SiC MOSFETs increases following NO passivation.

  3. Percolation mechanism through trapping/de-trapping process at defect states for resistive switching devices with structure of Ag/Si{sub x}C{sub 1?x}/p-Si

    SciTech Connect (OSTI)

    Liu, Yanhong; Gao, Ping; Li, La; Peng, Wei [School of Physics and Optoelectronic Engineering, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China); Jiang, Xuening; Zhang, Jialiang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China)

    2014-08-14

    Pure Si{sub x}C{sub 1?x} (x?>?0.5) and B-containing Si{sub x}C{sub 1?x} (x?>?0.5) based resistive switching devices (RSD) with the structure of Ag/Si{sub x}C{sub 1?x}/p-Si were fabricated and their switching characteristics and mechanism were investigated systematically. Percolation mechanism through trapping/ de-trapping at defect states was suggested for the switching process. Through the introduction of B atoms into Si{sub x}C{sub 1?x}, the density of defect states was reduced, then, the SET and RESET voltages were also decreased. Based on the percolation theory, the dependence of SET/RESET voltage on the density of defect states was analyzed. These results supply a deep understanding for the SiC-based RSD, which have a potential application in extreme ambient conditions.

  4. Simultaneous presence of (Si{sub 3}O{sub 10}){sup 8?} and (Si{sub 2}O{sub 7}){sup 6?} groups in new synthetic mixed sorosilicates: BaY{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}) and isotypic compounds, studied by single-crystal X-ray diffraction, Raman spectroscopy and DFT calculations

    SciTech Connect (OSTI)

    Wierzbicka-Wieczorek, Maria; Tbbens, Daniel M.; Kolitsch, Uwe; Tillmanns, Ekkehart

    2013-11-15

    Three new, isotypic silicate compounds, BaY{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}), SrYb{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}) and SrSc{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}), were synthesized using high-temperature flux growth techniques, and their crystal structures were solved from single-crystal X-ray intensity data: monoclinic, P2{sub 1}/m, with a=5.532(1)/5.469(1)/5.278(1), b=19.734(4)/19.447(4)/19.221(4), c=6.868(1)/6.785(1)/6.562(1) , ?=106.53(3)/106.20(3)/106.50(3), V=718.8(2)/693.0(2)/638.3(2) {sup 3}, R(F)=0.0225/0.0204/0.0270, respectively. The topology of the novel structure type contains isolated horseshoe-shaped Si{sub 3}O{sub 10} groups (SiSiSi=93.1595.98), Si{sub 2}O{sub 7} groups (SiO{sub bridge}Si=180, symmetry-restricted) and edge-sharing M(1)O{sub 6} and M(2)O{sub 6} octahedra. Single-crystal Raman spectra of the title compounds were measured and compared with Raman spectroscopic data of chemically and topologically related disilicates and trisilicates, including BaY{sub 2}(Si{sub 3}O{sub 10}) and SrY{sub 2}(Si{sub 3}O{sub 10}). The band assignments are supported by additional theoretical calculation of Raman vibrations by DFT methods. - Graphical abstract: View of BaY{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}) along [100], showing zigzag chains and the tri- and disilicate groups. The unit cell is outlined. Display Omitted - Highlights: We report a novel interesting crystal structure type for mixed sorosilicates containing Y, Yb, and Sc. Synthesis of such mixed sorosilicates is possible by a high-temperature flux-growth technique. Calculation of Raman vibrations by advanced DFT methods allows a considerably improved interpretation of measured Raman spectra.

  5. Disorder dependent half-metallicity in Mn{sub 2}CoSi inverse Heusler alloy

    SciTech Connect (OSTI)

    Singh, Mukhtiyar; Saini, Hardev S.; Thakur, Jyoti; Reshak, Ali H.; Kashyap, Manish K.

    2013-12-15

    Heusler alloys based thin-films often exhibit a degree of atomic disorder which leads to the lowering of spin polarization in spintronic devices. We present ab-initio calculations of atomic disorder effects on spin polarization and half-metallicity of Mn{sub 2}CoSi inverse Heusler alloy. The five types of disorder in Mn{sub 2}CoSi have been proposed and investigated in detail. The A2{sub a}-type and B2-type disorders destroy the half-metallicity whereas it sustains for all disorders concentrations in DO{sub 3a}- and A2{sub b}-type disorder and for smallest disorder concentration studied in DO{sub 3b}-type disorder. Lower formation energy/atom for A2{sub b}-type disorder than other four disorders in Mn{sub 2}CoSi advocates the stability of this disorder. The total magnetic moment shows a strong dependence on the disorder and the change in chemical environment. The 100% spin polarization even in the presence of disorders explicitly supports that these disorders shall not hinder the use of Mn{sub 2}CoSi inverse Heusler alloy in device applications. - Graphical abstract: Minority-spin gap (E{sub g↓}) and HM gap (E{sub sf}) as a function of concentrations of various possible disorder in Mn{sub 2}CoSi inverse Heusler alloy. The squares with solid line (black color)/dotted line (blue color)/dashed line (red color) reperesents E{sub g↓} for DO{sub 3a}-/DO{sub 3b}-/A2{sub b}-type disorder in Mn{sub 2}CoSi and the spheres with solid line (black color)/dottedline (blue color)/dashed line (red color) represents E{sub sf} for DO{sub 3a}-/DO{sub 3b}-/A2{sub b}-type disorder in Mn{sub 2}CoSi. - Highlights: • The DO{sub 3}- and A2-type disorders do not affect the half-metallicity in Mn{sub 2}CoSi. • The B2-type disorder solely destroys half-metallicity in Mn{sub 2}CoSi. • The A2-type disorder most probable to occur out of all three types. • The total spin magnetic moment strongly depends on the disorder concentrations.

  6. Understanding Light-Induced Degradation of c-Si Solar Cells: Preprint

    SciTech Connect (OSTI)

    Sopori, B.; Basnyat, P.; Devayajanam, S.; Shet, S.; Mehta, V.; Binns, J.; Appel, J.

    2012-06-01

    We discuss results of our investigations toward understanding bulk and surface components of light-induced degradation (LID) in low-Fe c-Si solar cells. The bulk effects, arising from boron-oxygen defects, are determined by comparing degradation of cell parameters and their thermal recovery, with that of the minority-carrier lifetime (964;) in sister wafers. We found that the recovery of 964; in wafers takes a much longer annealing time compared to that of the cell. We also show that cells having SiN:H coating experience a surface degradation (ascribed to surface recombination). The surface LID is seen as an increase in the q/2kT component of the dark saturation current (J02). The surface LID does not recover fully upon annealing and is attributed to degradation of the SiN:H-Si interface. This behavior is also exhibited by mc-Si cells that have very low oxygen content and do not show any bulk degradation.

  7. Tuning From Half-Metallic to Semiconducting Behavior in SiC Nanoribbons

    SciTech Connect (OSTI)

    Lopez-Benzanilla, Alejandro; Huang, Jingsong; Kent, Paul R; Sumpter, Bobby G

    2013-01-01

    Half-metallic nanoscale conductors, highly sought after for spintronic applications, are usually realized through metal elements, chemical doping, or external electric fields. By means of local and hybrid density functional theory calculations, we identify pristine zigzag silicon carbide nanoribbons (zSiC-NRs) with bare edges as a metal-free monolayered material that exhibits intrinsic half-metallic behavior without chemical doping or external electric field. Ab initio molecular dynamics simulations indicate that the half-metallicity is robust at room temperature. We also demonstrate that edge termination with O and S atoms transforms the zSiC-NRs into a full metal or a semiconducting material, respectively, due to the presence of O dimerization only on the Si edge and of S trimerization on both Si and C edges, the latter being driven by an unusual Peierls-like distortion along the functionalizing S atoms. The rich electronic properties displayed by zSiC-NRs may open new perspectives for spintronic applications using layered, metal-free, and light atom material.

  8. The correlation of epitaxial graphene properties and morphology of SiC (0001)

    SciTech Connect (OSTI)

    Guo, Y.; Guo, L. W., E-mail: lwguo@iphy.ac.cn, E-mail: xlchen@iphy.ac.cn; Huang, J.; Jia, Y. P.; Lin, J. J.; Lu, W.; Li, Z. L. [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, R. [Nanoscale Physics and Devices Laboratory, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Chen, X. L., E-mail: lwguo@iphy.ac.cn, E-mail: xlchen@iphy.ac.cn [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

    2014-01-28

    The electronic properties of epitaxial graphene (EG) on SiC (0001) depend sensitively on the surface morphology of SiC substrate. Here, 23 layers of graphene were grown on on-axis 6H-SiC with different step densities realized through controlling growth temperature and ambient pressure. We show that epitaxial graphene on SiC (0001) with low step density and straight step edge possesses fewer point defects laying mostly on step edges and higher carrier mobility. A relationship between step density and EG mobility is established. The linear scan of Raman spectra combined with the atomic force microscopy morphology images revealed that the Raman fingerprint peaks are nearly the same on terraces, but shift significantly while cross step edges, suggesting the graphene is not homogeneous in strain and carrier concentration over terraces and step edges of substrates. Thus, control morphology of epitaxial graphene on SiC (0001) is a simple and effective method to pursue optimal route for high quality graphene and will be helpful to prepare wafer sized graphene for device applications.

  9. Effects of temperature and pressure on phonons in FeSi1–xAlx

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Delaire, O.; Al-Qasir, I. I.; Ma, J.; dos Santos, A. M.; Sales, B. C.; Mauger, L.; Stone, M. B.; Abernathy, D. L.; Xiao, Y.; Somayazulu, M.

    2013-05-31

    The effects of temperature and pressure on phonons in B20 compounds FeSi1–xAlx were measured using inelastic neutron scattering and nuclear-resonant inelastic x-ray scattering. The effect of hole doping through Al substitution is compared to results of alloying with Co (electron doping) in Fe₁₋xCoxSi. While the temperature dependence of phonons in FeSi is highly anomalous, doping with either type of carriers leads to a recovery of the normal quasiharmonic behavior. Density functional theory (DFT) computations of the electronic band structure and phonons were performed. The anomaly in the temperature dependence of the phonons in undoped FeSi was related to the narrowmore » band gap, and its sensitivity to the effect of thermal disordering by phonons. On the other hand, the pressure dependence of phonons at room temperature in undoped FeSi follows the quasiharmonic behavior and is well reproduced by the DFT calculations.« less

  10. Epitaxial growth of highly conductive RuO{sub 2} thin films on (100) Si

    SciTech Connect (OSTI)

    Jia, Q.X.; Song, S.G.; Wu, X.D.; Cho, J.H.; Foltyn, S.R.; Findikoglu, A.T.; Smith, J.L.

    1996-02-01

    Conductive RuO{sub 2} thin films have been heteroepitaxially grown by pulsed laser deposition on Si substrates with yttria-stabilized zirconia (YSZ) buffer layers. The RuO{sub 2} thin films deposited under optimized processing conditions are {ital a}-axis oriented normal to the Si substrate surface with a high degree of in-plane alignment with the major axes of the (100) Si substrate. Cross-sectional transmission electron microscopy analysis on the RuO{sub 2}/YSZ/Si multilayer shows an atomically sharp interface between the RuO{sub 2} and the YSZ. Electrical measurements show that the crystalline RuO{sub 2} thin films are metallic over a temperature range from 4.2 to 300 K and are highly conductive with a room-temperature resistivity of 37{plus_minus}2 {mu}{Omega}cm. The residual resistance ratio ({ital R}{sub 300K}/{ital R}{sub 4.2K}) above 5 for our RuO{sub 2} thin films is the highest ever reported for such films on Si substrates. {copyright} {ital 1996 American Institute of Physics.}

  11. Early implementation of SiC cladding fuel performance models in BISON

    SciTech Connect (OSTI)

    Powers, Jeffrey J.

    2015-09-18

    SiC-based ceramic matrix composites (CMCs) [5–8] are being developed and evaluated internationally as potential LWR cladding options. These development activities include interests within both the DOE-NE LWR Sustainability (LWRS) Program and the DOE-NE Advanced Fuels Campaign. The LWRS Program considers SiC ceramic matrix composites (CMCs) as offering potentially revolutionary gains as a cladding material, with possible benefits including more efficient normal operating conditions and higher safety margins under accident conditions [9]. Within the Advanced Fuels Campaign, SiC-based composites are a candidate ATF cladding material that could achieve several goals, such as reducing the rates of heat and hydrogen generation due to lower cladding oxidation rates in HT steam [10]. This work focuses on the application of SiC cladding as an ATF cladding material in PWRs, but these work efforts also support the general development and assessment of SiC as an LWR cladding material in a much broader sense.

  12. Corrosion protection of SiC-based ceramics with CVD mullite coatings

    SciTech Connect (OSTI)

    Sarin, V.; Mulpuri, R.; Auger, M.

    1996-04-20

    SiC based ceramics have been identified as the leading candidate materials for elevated temperature applications in harsh oxidation/corrosion environments. It has been established that a protective coating can be effectively used to avoid problems with excessive oxidation and hot corrosion. However, to date, no coating configuration has been developed that can withstand the rigorous requirements imposed by such applications. Chemical vapor deposited (CVD) mullite coatings due to their desirable properties of toughness, corrosion resistance, and good coefficient of thermal expansion match with SiC are being developed as a potential solution. Formation of mullite on ceramic substrates via chemical vapor deposition was investigated. Thermodynamic calculations performed on the AlCl{sub 3}- SiCl{sub 4}-CO{sub 2}-H{sub 2} system were used to construct equilibrium CVD phase diagrams. Through process optimization, crystalline CVD mullite coatings have been successfully grown on SiC and Si{sub 3}N{sub 4} substrates. Results from the thermodynamic analysis, process optimization, and effect of various process parameters on deposition rate and coating morphology are discussed.

  13. High-quality epitaxial CoFe/Si(111) heterostructures fabricated by low-temperature molecular beam epitaxy

    SciTech Connect (OSTI)

    Maeda, Y.; Yamada, S.; Ando, Y.; Yamane, K.; Miyao, M.; Hamaya, K.

    2010-11-08

    We demonstrate atomically controlled heterojunctions consisting of ferromagnetic CoFe alloys and silicon (Si) using low-temperature molecular beam epitaxy with a good atomic matching at the (111) plane. The saturation magnetization of the CoFe layers grown reaches {approx}85% of the value of bulk samples reported so far, and can be systematically controlled by tuning the ratio of Co to Fe, indicating that the silicidation reactions between CoFe and Si are suppressed and the heterojunctions are very high quality. We find that the Schottky barrier height of the high-quality CoFe/Si(111) junctions is unexpectedly low compared to the previous data for other metal/Si ones, implying the reduction in the Fermi-level-pinning effect. We can expand the available high-quality ferromagnet/Si heterostructures in the field of Si-based spintronics.

  14. Hydrogenation Methods and Passivation Mechanisms for c-Si Photovoltaics: Final Technical Report, 2 January 2002 - 15 January 2008

    SciTech Connect (OSTI)

    Estreicher, S. K.

    2008-11-01

    Joint experimental and theortetical research program to improve processes used to eliminate or passivate lifetime-reducing defects in the Si bulk.

  15. Characterization of plasma chemistry and ion energy in cathodic arc plasma from Ti-Si cathodes of different compositions

    SciTech Connect (OSTI)

    Eriksson, A. O.; Zhirkov, I.; Dahlqvist, M.; Jensen, J.; Hultman, L.; Rosen, J.

    2013-04-28

    Arc plasma from Ti-Si compound cathodes with up to 25 at. % Si was characterized in a DC arc system with respect to chemistry and charge-state-resolved ion energy. The plasma ion composition showed a lower Si content, diverging up to 12 at. % compared to the cathode composition, yet concurrently deposited films were in accordance with the cathode stoichiometry. Significant contribution to film growth from neutrals is inferred besides ions, since the contribution from macroparticles, estimated by scanning electron microscopy, cannot alone account for the compositional difference between cathode, plasma, and film. The average ion charge states for Ti and Si were higher than reference data for elemental cathodes. This result is likely related to TiSi{sub x} phases of higher cohesive energies in the compound cathodes and higher effective electron temperature in plasma formation. The ion energy distributions extended up to {approx}200 and {approx}130 eV for Ti and Si, respectively, with corresponding average energies of {approx}60 and {approx}30 eV. These averages were, however, not dependent on Si content in the cathode, except for 25 at. % Si where the average energies were increased up to 72 eV for Ti and 47 eV for Si.

  16. X-ray nano-diffraction study of Sr intermetallic phase during solidification of Al-Si hypoeutectic alloy

    SciTech Connect (OSTI)

    Manickaraj, Jeyakumar; Gorny, Anton; Shankar, Sumanth, E-mail: shankar@mcmaster.ca [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S 4L7 (Canada); Cai, Zhonghou [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2014-02-17

    The evolution of strontium (Sr) containing intermetallic phase in the eutectic reaction of Sr-modified Al-Si hypoeutectic alloy was studied with high energy synchrotron beam source for nano-diffraction experiments and x-ray fluorescence elemental mapping. Contrary to popular belief, Sr does not seem to interfere with the Twin Plane Re-entrant Edge (TPRE) growth mechanism of eutectic Si, but evolves as the Al{sub 2}Si{sub 2}Sr phase during the eutectic reaction at the boundary between the eutectic Si and Al grains.

  17. Thin Film Si Bottom Cells for Tandem Device Structures: Final Technical Report, 15 December 2003 - 15 October 2007

    SciTech Connect (OSTI)

    Yelundur, V.; Hegedus, S.; Rohatgi, A.; Birkmire, R.

    2008-11-01

    GIT and IEC developed thin-film Si bottom cell and showed that deposition of top cell in tandem device did not reduce bottom cell performance.

  18. Spectroscopic ellipsometry on Si/SiO{sub 2}/graphene tri-layer system exposed to downstream hydrogen plasma: Effects of hydrogenation and chemical sputtering

    SciTech Connect (OSTI)

    Eren, Baran; Fu, Wangyang; Marot, Laurent Calame, Michel; Steiner, Roland; Meyer, Ernst

    2015-01-05

    In this work, the optical response of graphene to hydrogen plasma treatment is investigated with spectroscopic ellipsometry measurements. Although the electronic transport properties and Raman spectrum of graphene change after plasma hydrogenation, ellipsometric parameters of the Si/SiO2/graphene tri-layer system do not change. This is attributed to plasma hydrogenated graphene still being electrically conductive, since the light absorption of conducting 2D materials does not depend on the electronic band structure. A change in the light transmission can only be observed when higher energy hydrogen ions (30?eV) are employed, which chemically sputter the graphene layer. An optical contrast is still apparent after sputtering due to the remaining traces of graphene and hydrocarbons on the surface. In brief, plasma treatment does not change the light transmission of graphene; and when it does, this is actually due to plasma damage rather than plasma hydrogenation.

  19. Progress towards a 30% efficient GaInP/Si tandem solar cells

    SciTech Connect (OSTI)

    Essig, Stephanie; Ward, Scott; Steiner, Myles A.; Friedman, Daniel J.; Geisz, John F.; Stradins, Paul; Young, David L.

    2015-08-28

    The performance of dual-junction solar cells with a Si bottom cell has been investigated both theoretically and experimentally. Simulations show that adding a top junction with an energy bandgap of 1.6 -1.9 eV to a standard silicon solar cell enables efficiencies over 38%. Currently, top junctions of GaInP (1.8 eV) are the most promising as they can achieve 1-sun efficiencies of 20.8% [1]. We fabricated mechanically stacked, four terminal GaInP/Si tandem solar cells using a transparent adhesive between the subcells. These tandem devices achieved an efficiency of 27% under AM1.5 g spectral conditions. Furthermore, higher efficiencies can be achieved by using an improved Si-bottom cell and by optimizing the dual-junction device for long-wavelength light and luminescent coupling between the two junctions.

  20. Progress towards a 30% efficient GaInP/Si tandem solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Essig, Stephanie; Ward, Scott; Steiner, Myles A.; Friedman, Daniel J.; Geisz, John F.; Stradins, Paul; Young, David L.

    2015-08-28

    The performance of dual-junction solar cells with a Si bottom cell has been investigated both theoretically and experimentally. Simulations show that adding a top junction with an energy bandgap of 1.6 -1.9 eV to a standard silicon solar cell enables efficiencies over 38%. Currently, top junctions of GaInP (1.8 eV) are the most promising as they can achieve 1-sun efficiencies of 20.8% [1]. We fabricated mechanically stacked, four terminal GaInP/Si tandem solar cells using a transparent adhesive between the subcells. These tandem devices achieved an efficiency of 27% under AM1.5 g spectral conditions. Furthermore, higher efficiencies can be achieved bymore » using an improved Si-bottom cell and by optimizing the dual-junction device for long-wavelength light and luminescent coupling between the two junctions.« less

  1. Enhancing optical gains in Si nanocrystals via hydrogenation and cerium ion doping

    SciTech Connect (OSTI)

    Wang, Dong-Chen; Li, Yan-Li; Song, Sheng-Chi; Guo, Wen-Ping; Lu, Ming; Chen, Jia-Rong

    2014-07-28

    We report optical gain enhancements in Si nanocrystals (Si-NCs) via hydrogenation and Ce{sup 3+} ion doping. Variable stripe length technique was used to obtain gains. At 0.3 W/cm{sup 2} pumping power density of pulsed laser, net gains were observed together with gain enhancements after hydrogenation and/or Ce{sup 3+} ion doping; gains after loss corrections were between 89.52 and 341.95 cm{sup −1}; and the photoluminescence (PL) lifetime was found to decrease with the increasing gain enhancement. At 0.04 W/cm{sup 2} power density, however, no net gain was found and the PL lifetime increased with the increasing PL enhancement. The results were discussed according to stimulated and spontaneous excitation and de-excitation mechanisms of Si-NCs.

  2. Non-Contact Printed Aluminum Metallization of Si Photovoltaic Devices: Preprint

    SciTech Connect (OSTI)

    Platt, H. A. S.; van Hest, M. F. A. M.; Li, Y.; Novak, J. P.

    2012-06-01

    Alternative solution-based techniques such as aerosol jet printing offer the dual benefits of contactless pattern deposition and high material utilization. We have used aerosol jet printing to investigate non-contact printed Al metal ink as a replacement for screen printed Al back contacts on wafer Si solar cells. This particle-based ink can be prepared at high loadings of 60 weight % metal, which enables rapid deposition of 1 - 10 um thick lines. Al lines printed on Si wafers and heated between 550 and 800 degrees C form low resistance contacts suitable for current extraction. The effectiveness of these printed Al back contacts has further been demonstrated by incorporating them into a series of 21 cm2 crystalline Si solar cells that produced a champion power conversion efficiency of 13%.

  3. Emission Properties from ZnO Quantum Dots Dispersed in SiO{sub 2} Matrix

    SciTech Connect (OSTI)

    Panigrahi, Shrabani; Basak, Durga

    2011-07-15

    Dispersion of ZnO quantum dots in SiO{sub 2} matrix has been achieved in two techniques based on StOeber method to form ZnO QDs-SiO{sub 2} nanocomposites. Sample A is formed with random dispersion by adding tetraethyl orthosilicate (TEOS) to an ethanolic solution of ZnO nanoparticles and sample B is formed with a chain-like ordered dispersion by adding ZnO nanoparticles to an already hydrolyzed ethanolic TEOS solution. The photoluminescence spectra of the as-grown nanocomposites show strong emission in the ultraviolet region. When annealed at higher temperature, depending on the sample type, these show strong red or white emission. Interestingly, when the excitation is removed, the orderly dispersed ZnO QDs-SiO{sub 2} composite shows a very bright blue fluorescence visible by naked eyes for few seconds indicating their promise for display applications.

  4. Band alignment and interfacial structure of ZnO/Si heterojunction with

    Office of Scientific and Technical Information (OSTI)

    Al{sub 2}O{sub 3} and HfO{sub 2} as interlayers (Journal Article) | SciTech Connect Band alignment and interfacial structure of ZnO/Si heterojunction with Al{sub 2}O{sub 3} and HfO{sub 2} as interlayers Citation Details In-Document Search Title: Band alignment and interfacial structure of ZnO/Si heterojunction with Al{sub 2}O{sub 3} and HfO{sub 2} as interlayers Energy band alignment of ZnO/Si heterojunction with thin interlayers Al{sub 2}O{sub 3} and HfO{sub 2} grown by atomic layer

  5. Elasticity and magnetocaloric effect in MnFe4Si3

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Herlitschke, Marcus; Klobes, B.; Sergueev, I.; Hering, Paul; Persson, Joerg; Hermann, Raphael P.

    2016-03-16

    The room temperature magnetocaloric material MnFe4Si3 was investigated with nuclear inelastic scattering (NIS) and resonant ultrasound spectroscopy (RUS) at different temperatures and applied magnetic fields in order to assess the infuence of the magnetic transition and the magnetocaloric effect on the lattice dynamics. The NIS data give access to phonons with energies above 3 meV, whereas RUS probes the elasticity of the material in the MHz frequency range and thus low energy, ~5 neV, phonon modes. A significant infuence of the magnetic transition on the lattice dynamics is observed only in the low energy region. Here, MnFe4Si3 and other compoundsmore » in the Mn5-xFexSi3 series were also investigated with vibrating sample magnetometry, resistivity measurements and Moessbauer spectroscopy in order to study the magnetic transitions and to complement the obtained results on the lattice dynamics.« less

  6. Manipulating hybrid structures of polymer/a-Si for thin film solar cells

    SciTech Connect (OSTI)

    Peng, Ying; He, Zhiqun, E-mail: zhqhe@bjtu.edu.cn, E-mail: J.I.B.Wilson@hw.ac.uk; Zhang, Zhi; Liang, Chunjun [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Diyaf, Adel; Ivaturi, Aruna; Wilson, John I. B., E-mail: zhqhe@bjtu.edu.cn, E-mail: J.I.B.Wilson@hw.ac.uk [SUPA, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2014-03-10

    A series of uniform polymer/amorphous silicon hybrid structures have been fabricated by means of solution-casting for polymer and radio frequency excited plasma enhanced chemical vapour deposition for amorphous silicon (a-Si:H). Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) functioned as a photoactive donor, while the silicon layer acted as an acceptor. It is found that matching the hole mobility of the polymer to the electron mobility of amorphous silicon is critical to improve the photovoltaic performance from hybrid cells. A three-layer p-i-n structure of ITO/PEDOT:PSS(200?nm)/i-Si(450?nm)/n-Si(200?nm)/Al with a power conversion efficiency of 4.78% under a standard test condition was achieved.

  7. Effects of Contact Resistance on Electrical Conductivity Measurements of SiC-Based Materials

    SciTech Connect (OSTI)

    Youngblood, Gerald E.; Thomsen, Edwin C.; Henager, Charles H.

    2012-04-17

    A combination 2/4-probe method was used to measure electrical resistances across a pure, monolithic CVD-SiC disc sample with contact resistance at the SiC/metallic electrode interfaces. By comparison of the almost simultaneous 2/4-probe measurements, the specific contact resistance and its temperature dependence were determined for two types (sputtered gold and porous nickel) electrodes from RT to ~700C. The specific contact resistance values (Rc) behaved similarly for each type of metallic electrode: Rc >~1000 ?-cm2 at RT, decreasing continuously to ~1-10 ?-cm2 at 700C. The temperature dependence of the inverse Rc indicated thermally activated electrical conduction across the SiC/metallic interface with an apparent activation energy of ~0.3 eV. For the flow channel insert application in a fusion reactor blanket, contact resistance potentially could reduce the transverse electrical conductivity by ~1/2.

  8. Effects of contact resistance on electrical conductivity measurements of SiC-based materials

    SciTech Connect (OSTI)

    Youngblood, Gerald E.; Thomsen, Edwin C.; Henager, Charles H.

    2013-06-30

    A combination 2/4-probe method was used to measure electrical resistances across a pure, monolithic CVD-SiC disc sample with contact resistance at the SiC/metallic electrode interfaces. By comparison of the almost simultaneous 2/4-probe measurements, the specific contact resistance (Rc) and its temperature dependence were determined for two types (sputtered gold and porous nickel) electrodes from room temperature (RT) to ?973 K. The Rc-values behaved similarly for each type of metallic electrode: Rc > ?1000 ? cm2 at RT, decreasing continuously to ?110 ? cm2 at 973 K. The temperature dependence of the inverse Rc indicated thermally activated electrical conduction across the SiC/metallic interface with an apparent activation energy of ?0.3 eV. For the flow channel insert application in a fusion reactor blanket, contact resistance potentially could reduce the transverse electrical conductivity by about 50%.

  9. Effect of growth temperature on ballistic electron transport through the Au/Si(001) interface

    SciTech Connect (OSTI)

    Eckes, M. W.; Friend, B. E.; Stollenwerk, A. J.

    2014-04-28

    Ballistic electron emission spectroscopy was used to investigate electron transport through Au/Si(001) Schottky diodes grown at 35?C and 22?C. Aside from a decreased Schottky height, this small increase in temperature introduced an energy dependent scattering component, which was absent in the samples grown at 22?C. These differences may be attributed to the increased amount of Au-Si intermixing at the interface. Despite the non-epitaxial nature of the growth technique, strong evidence was found in both sets of samples that indicated the presence of a forward-focused current subject to some degree of parallel momentum conservation at the interface. This evidence was present in all samples grown at 35?C, but was only observed in those samples grown at 22?C when the Au films were 10?nm or thicker. This sensitivity to growth temperature could account for discrepancies in previous studies on Au/Si(001)

  10. Electronic Band Structure And Kondo Coupling in YbRh(2)Si(2)

    SciTech Connect (OSTI)

    Wigger, G.A.; Baumberger, F.; Shen, Z.X.; Yin, Z.P.; Pickett, W.E.; Maquilon, S.; Fisk, Z.; /UC, Davis

    2007-09-26

    The electronic band structure of YbRh{sub 2}Si{sub 2} is calculated in a relativistic framework including correlation corrections and magnetization of the Yb ion and compared to detailed angle-resolved photoemission spectra. The photoemission spectra for LuRh{sub 2}Si{sub 2} are used as reference to identify electronic bands with no f symmetry. The calculated band structure manifests a 4f{sup 13} spin-polarized configuration leaving the unoccupied state at 1.4 eV above the Fermi energy. At the band theory level, the 4f bands are located far below the Fermi level and the anisotropic Coulomb interaction within the 4f shell spreads the multilevel into broader 4f complexes below -2.5 eV. The photoemission spectra obtained on YbRh2Si2 show a clear f-multilevel splitting into j=7/2 and 5/2 excitations. The interaction of the 4f{sub 7/2} levels close to the Fermi energy with two conduction bands shows visible hybridization gaps of 45 and 80 meV, respectively. We discuss the origin of these excitations and provide an analysis according to Anderson's single-impurity model with parameters suggested by the band-structure calculation and the photoemission spectra. Both experiment and theory indicate nearly identical Fermi surfaces for LuRh{sub 2}Si{sub 2} and YbRh{sub 2}Si{sub 2}. The valency of Yb in YbRh{sub 2}Si{sub 2} is estimated to be close to +3.

  11. Fluorocarbon assisted atomic layer etching of SiO2 and Si using cyclic Ar/C4F8 and Ar/CHF3 plasma

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-11

    The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C4F8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C4F8 injection and synchronized plasma-based low energy Ar+ ion bombardment has been established for SiO2.1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF3 as a precursor is examined and compared to C4F8. CHF3 is shown to enable selective SiO2/Si etching using a fluorocarbon (FC) film build up. Othermore » critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

  12. Structure of 5-hydroxymethylcytosine-specific restriction enzyme, AbaSI, in complex with DNA

    SciTech Connect (OSTI)

    Horton, John R.; Borgaro, Janine G.; Griggs, Rose M.; Quimby, Aine; Guan, Shengxi; Zhang, Xing; Wilson, Geoffrey G.; Zheng, Yu; Zhu, Zhenyu; Cheng, Xiaodong

    2014-07-03

    AbaSI, a member of the PvuRts1I-family of modification-dependent restriction endonucleases, cleaves DNA containing 5-hydroxymethylctosine (5hmC) and glucosylated 5hmC (g5hmC), but not DNA containing unmodified cytosine. AbaSI has been used as a tool for mapping the genomic locations of 5hmC, an important epigenetic modification in the DNA of higher organisms. Here we report the crystal structures of AbaSI in the presence and absence of DNA. These structures provide considerable, although incomplete, insight into how this enzyme acts. AbaSI appears to be mainly a homodimer in solution, but interacts with DNA in our structures as a homotetramer. Each AbaSI subunit comprises an N-terminal, Vsr-like, cleavage domain containing a single catalytic site, and a C-terminal, SRA-like, 5hmC-binding domain. Two N-terminal helices mediate most of the homodimer interface. Dimerization brings together the two catalytic sites required for double-strand cleavage, and separates the 5hmC binding-domains by ~ 70 , consistent with the known activity of AbaSI which cleaves DNA optimally between symmetrically modified cytosines ~ 22 bp apart. The eukaryotic SET and RING-associated (SRA) domains bind to DNA containing 5-methylcytosine (5mC) in the hemi-methylated CpG sequence. They make contacts in both the major and minor DNA grooves, and flip the modified cytosine out of the helix into a conserved binding pocket. In contrast, the SRA-like domain of AbaSI, which has no sequence specificity, contacts only the minor DNA groove, and in our current structures the 5hmC remains intra-helical. A conserved, binding pocket is nevertheless present in this domain, suitable for accommodating 5hmC and g5hmC. We consider it likely, therefore, that base-flipping is part of the recognition and cleavage mechanism of AbaSI, but that our structures represent an earlier, pre-flipped stage, prior to actual recognition.

  13. High efficiency thin film CdTe and a-Si based solar cells

    SciTech Connect (OSTI)

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10{sup {minus}5} torr) was beneficial for growing high-quality films from ITO targets.

  14. Momentum-space structure of quasielastic spin fluctuations in Ce 3 Pd 20 Si

    Office of Scientific and Technical Information (OSTI)

    6 (Journal Article) | SciTech Connect Momentum-space structure of quasielastic spin fluctuations in Ce 3 Pd 20 Si 6 Citation Details In-Document Search Title: Momentum-space structure of quasielastic spin fluctuations in Ce 3 Pd 20 Si 6 Authors: Portnichenko, P. Y. ; Cameron, A. S. ; Surmach, M. A. ; Deen, P. P. ; Paschen, S. ; Prokofiev, A. ; Mignot, J.-M. ; Strydom, A. M. ; Telling, M. T. F. ; Podlesnyak, A. ; Inosov, D. S. Publication Date: 2015-03-13 OSTI Identifier: 1179978 Type:

  15. Oxidation-resistant, solution-processed plasmonic Ni nanochain-SiO{sub x}

    Office of Scientific and Technical Information (OSTI)

    (x < 2) selective solar thermal absorbers (Journal Article) | SciTech Connect Oxidation-resistant, solution-processed plasmonic Ni nanochain-SiO{sub x} (x < 2) selective solar thermal absorbers Citation Details In-Document Search Title: Oxidation-resistant, solution-processed plasmonic Ni nanochain-SiO{sub x} (x < 2) selective solar thermal absorbers Metal oxidation at high temperatures has long been a challenge in cermet solar thermal absorbers, which impedes the development of

  16. Incorporation of Catalytic Compounds in the Porosity of SiC Wall Flow

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Filters - 4 Way Catalyst and DeNOx Application examples | Department of Energy Incorporation of Catalytic Compounds in the Porosity of SiC Wall Flow Filters - 4 Way Catalyst and DeNOx Application examples Incorporation of Catalytic Compounds in the Porosity of SiC Wall Flow Filters - 4 Way Catalyst and DeNOx Application examples 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 August, 2007, Detroit, Michigan. Sponsored by the U.S. Department of Energy's

  17. Depth Profiling of SiC Lattice Damage Using Micro-Raman Spectroscopy

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Depth Profiling of SiC Lattice Damage Using Micro-Raman Spectroscopy Citation Details In-Document Search Title: Depth Profiling of SiC Lattice Damage Using Micro-Raman Spectroscopy Depth profiling for the amount of lattice damage using a Confocal Micro-Raman (CMR) spectrometer is demonstrated in this paper. Samples of n-type silicon carbide were implanted with 2 MeV He and O ions at both room temperature and 500 C, and fluences between 10{sup 15} and 10{sup 17}

  18. Electronic Structure and Morphology of Graphene Films on SiC. (Conference)

    Office of Scientific and Technical Information (OSTI)

    | SciTech Connect Conference: Electronic Structure and Morphology of Graphene Films on SiC. Citation Details In-Document Search Title: Electronic Structure and Morphology of Graphene Films on SiC. Abstract not provided. Authors: Ohta, Taisuke Publication Date: 2008-02-01 OSTI Identifier: 1146028 Report Number(s): SAND2008-1363C 519195 DOE Contract Number: DE-AC04-94AL85000 Resource Type: Conference Resource Relation: Conference: APS March Meeting held March 9-14, 2008 in New Orleans, LA.;

  19. Equation of state and phase diagram of Fe-16Si alloy as a candidate

    Office of Scientific and Technical Information (OSTI)

    component of Earth's core (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Equation of state and phase diagram of Fe-16Si alloy as a candidate component of Earth's core Citation Details In-Document Search Title: Equation of state and phase diagram of Fe-16Si alloy as a candidate component of Earth's core The outer core of the Earth contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is critical to

  20. Formation of quantum spin Hall state on Si surface and energy gap scaling

    Office of Scientific and Technical Information (OSTI)

    with strength of spin orbit coupling (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling Citation Details In-Document Search Title: Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling For potential applications in spintronics and quantum computing, it is desirable to place a quantum spin Hall

  1. Formation of quantum spin Hall state on Si surface and energy gap scaling

    Office of Scientific and Technical Information (OSTI)

    with strength of spin orbit coupling (Journal Article) | SciTech Connect Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling Citation Details In-Document Search Title: Formation of quantum spin Hall state on Si surface and energy gap scaling with strength of spin orbit coupling × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical

  2. Proposed Route to Thin Film Crystal Si Using Biaxially Textured Foreign Template Layers

    SciTech Connect (OSTI)

    Teplin, C. W.; Ginley, D. S.; van Hest, M.F.A.M.; Perkins, J. D.; Young, D. L.; Stradins, P.; Wang, Q.; Al-Jassim, M.; Iwaniczko, E.; Leenheer, A.; Jones, K. M.; Branz, H. M.

    2005-11-01

    We have developed a new approach to growing photovoltaic-quality crystal silicon (c-Si) films on glass. Other approaches to film c-Si focus on increasing grain size in order to reduce the deleterious effects of grain boundaries. Instead, we have developed an approach to align the silicon grains biaxially (both in and out of plane) so that 1) grain boundaries are "low-angle" and have less effect on the electronic properties of the material and 2) subsequent epitaxial thickening is simplified. They key to our approach is the use of a foreign template layer that can be grown with biaxial texture directly on glass.

  3. Microstructural Contol of the Porous Si3N4 Ceramics Consisted of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    3-Dimensionally Intermingled Rod-like Grains | Department of Energy Contol of the Porous Si3N4 Ceramics Consisted of 3-Dimensionally Intermingled Rod-like Grains Microstructural Contol of the Porous Si3N4 Ceramics Consisted of 3-Dimensionally Intermingled Rod-like Grains Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 August, 2007, Detroit, Michigan. Sponsored by the U.S. Department of Energy's (DOE) Office of FreedomCAR and

  4. Fuel Consumption and NOx Trade-offs on a Port-Fuel-Injected SI Gasoline

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Engine Equipped with a Lean-NOx Trap | Department of Energy NOx Trade-offs on a Port-Fuel-Injected SI Gasoline Engine Equipped with a Lean-NOx Trap Fuel Consumption and NOx Trade-offs on a Port-Fuel-Injected SI Gasoline Engine Equipped with a Lean-NOx Trap Lean-burn improves PFI fuel economy by ~3% relative to best stoichiometric VCT/EGR conditions, when used in combination with VCT & EGR. PDF icon deer09_lymburner.pdf More Documents & Publications Vehicle Technologies Office Merit

  5. Direct Visualization of Spray and Combustion Inside a DI-SI Engine and Its

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Implications to Flex-Fuel VVT Operations | Department of Energy Visualization of Spray and Combustion Inside a DI-SI Engine and Its Implications to Flex-Fuel VVT Operations Direct Visualization of Spray and Combustion Inside a DI-SI Engine and Its Implications to Flex-Fuel VVT Operations Fuel, injection timing, and valve deactivation in a DI optical accessible engine with side-mounted, multi-hole injector are investigated using CFD and high-speed imaging of sprays and combustion. PDF icon

  6. Structure determination of (*3x*3)R30{sup o} boron phase on the Si(111)

    Office of Scientific and Technical Information (OSTI)

    surface using photoelectron diffraction (Journal Article) | SciTech Connect Structure determination of (*3x*3)R30{sup o} boron phase on the Si(111) surface using photoelectron diffraction Citation Details In-Document Search Title: Structure determination of (*3x*3)R30{sup o} boron phase on the Si(111) surface using photoelectron diffraction No abstract prepared. Authors: Baumgartel, P. ; Paggel, J.J. ; Hasselblatt, M. ; Horn, K. ; Fernandez, V. ; Schaff, O. ; Weaver, J.H. ; Bradshaw, A.M. ;

  7. Effects of irradiation on the mechanical behavior of twined SiC nanowires

    SciTech Connect (OSTI)

    Jin Enze; Niu Lisha; Lin Enqiang; Duan Zheng [AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China)

    2013-03-14

    Irradiation is known to bring new features in one-dimensional nano materials. In this study, we used molecular dynamics simulations to investigate the irradiation effects on twined SiC nanowires. Defects tend to accumulate from outside toward inside of the twined SiC nanowires with increasing irradiation dose, leading to a transition from brittle to ductile failure under tensile load. Atomic chains are formed in the ductile failure process. The first-principles calculations show that most of the atomic chains are metallic.

  8. Photochemical switching behavior of azofunctionalized polymer liquid crystal/SiO{sub 2} composite photonic crystal

    SciTech Connect (OSTI)

    Moritsugu, M.; Kim, S. N.; Ogata, T.; Nonaka, T.; Kurihara, S.; Kubo, S.; Segawa, H.; Sato, O.

    2006-10-09

    A photochemically tunable photonic crystal was prepared by infiltrating azopolymer liquid crystal in a SiO{sub 2} inverse opal structure. The SiO{sub 2} inverse opal film obtained reflected a light corresponding to the periodicity as well as the refractive indices of the inverse opal structure. Linearly polarized light irradiation shifted the reflection band to longer wavelength more than 15 nm. This is caused by the formation of anisotropic molecular orientation of the azopolymer. The switched state was stable in the dark, and the reversible switching of the reflection band can be achieved by the linearly and circularly polarized light irradiations.

  9. SiC-CMC-Zircaloy-4 Nuclear Fuel Cladding Performance during 4-Point Tubular Bend Testing

    SciTech Connect (OSTI)

    IJ van Rooyen; WR Lloyd; TL Trowbridge; SR Novascone; KM Wendt; SM Bragg-Sitton

    2013-09-01

    The U.S. Department of Energy Office of Nuclear Energy (DOE NE) established the Light Water Reactor Sustainability (LWRS) program to develop technologies and other solutions to improve the reliability, sustain the safety, and extend the life of current reactors. The Advanced LWR Nuclear Fuel Development Pathway in the LWRS program encompasses strategic research focused on improving reactor core economics and safety margins through the development of an advanced fuel cladding system. Recent investigations of potential options for accident tolerant nuclear fuel systems point to the potential benefits of silicon carbide (SiC) cladding. One of the proposed SiC-based fuel cladding designs being investigated incorporates a SiC ceramic matrix composite (CMC) as a structural material supplementing an internal Zircaloy-4 (Zr-4) liner tube, referred to as the hybrid clad design. Characterization of the advanced cladding designs will include a number of out-of-pile (nonnuclear) tests, followed by in-pile irradiation testing of the most promising designs. One of the out-of-pile characterization tests provides measurement of the mechanical properties of the cladding tube using four point bend testing. Although the material properties of the different subsystems (materials) will be determined separately, in this paper we present results of 4-point bending tests performed on fully assembled hybrid cladding tube mock-ups, an assembled Zr-4 cladding tube mock-up as a standard and initial testing results on bare SiC-CMC sleeves to assist in defining design parameters. The hybrid mock-up samples incorporated SiC-CMC sleeves fabricated with 7 polymer impregnation and pyrolysis (PIP) cycles. To provide comparative information; both 1- and 2-ply braided SiC-CMC sleeves were used in this development study. Preliminary stress simulations were performed using the BISON nuclear fuel performance code to show the stress distribution differences for varying lengths between loading points and clad configurations. The 2-ply sleeve samples show a higher bend momentum compared to those of the 1-ply sleeve samples. This is applicable to both the hybrid mock-up and bare SiC-CMC sleeve samples. Comparatively both the 1- and 2-ply hybrid mock-up samples showed a higher bend stiffness and strength compared with the standard Zr-4 mock-up sample. The characterization of the hybrid mock-up samples showed signs of distress and preliminary signs of fraying at the protective Zr-4 sleeve areas for the 1-ply SiC-CMC sleeve. In addition, the microstructure of the SiC matrix near the cracks at the region of highest compressive bending strain shows significant cracking and flaking. The 2-ply SiC-CMC sleeve samples showed a more bonded, cohesive SiC matrix structure. This cracking and fraying causes concern for increased fretting during the actual use of the design. Tomography was proven as a successful tool to identify open porosity during pre-test characterization. Although there is currently insufficient data to make conclusive statements regarding the overall merit of the hybrid cladding design, preliminary characterization of this novel design has been demonstrated.

  10. Effects of nano-SiO{sub 2} particles on surface tracking characteristics of silicone rubber composites

    SciTech Connect (OSTI)

    Liu, Yong Li, Zhonglei; Du, Boxue

    2014-09-08

    Compared with neat silicone rubber composites (SiRCs), SiRCs filled with nano-sized SiO{sub 2} particles at weight ratios from 0.1 to 1.0?wt.?% exhibit a higher surface flashover voltage and a greater resistance to surface tracking. Scanning electron microscopy images of tracking morphologies indicate that the SiO{sub 2} particles are situated in close proximity to the polymeric chains and act as bridges to stabilize the chains and maintain the structure of the composite. Higher concentrations of nano-sized SiO{sub 2} particles, however, (above 0.3?wt.?%) produce defects in the molecular network which lead to reductions in both the surface flashover voltage and the resistance to surface tracking, although these reduced values are still superior to those of neat SiRCs. Therefore, SiRCs filled with nano-sized SiO{sub 2} particles, especially at an optimal weight ratio (0.1 to 0.3?wt.?%), may have significant potential applications as outdoor insulators for power systems.

  11. Ultrathin nanosheets of CrSiTe3: A semiconducting two-dimensional ferromagnetic material

    SciTech Connect (OSTI)

    Lin, Ming -Wei; Zhung, Houlong L.; Yan, Jiaqiang; Ward, Thomas Zac; Puretzky, Alexander A.; Rouleau, Christopher M.; Gai, Zheng; Liang, Liangbo; Meunier, Vincent; Ganesh, Panchapakesan; Kent, Paul R. C.; Sumpter, Bobby G.; Mandrus, David G.; Geohegan, David B.; Xiao, Kai

    2015-11-27

    Finite range ferromagnetism and antiferromagnetism in two-dimensional (2D) systems within an isotropic Heisenberg model at non-zero temperature were originally proposed to be impossible. However, recent theoretical studies using an Ising model have recently shown that 2D magnetic crystals can exhibit magnetism. Experimental verification of existing 2D magnetic crystals in this system has remained elusive. In this work we for the first time exfoliate the CrSiTe3, a bulk ferromagnetic semiconductor, to mono- and few-layer 2D crystals onto a Si/SiO2 substrate. The Raman spectra show the good stability and high quality of the exfoliated flakes, consistent with the computed phonon spectra of 2D CrSiTe3, giving a strong evidence for the existence of 2D CrSiTe3 crystals. When the thickness of the CrSiTe3 crystals is reduced to few-layers, we observed a clear change in resistivity at 80~120 K, consistent with the theoretical calculations on the Curie temperature (Tc) of ~80 K for the magnetic ordering of 2D CrSiTe3 crystals. As a result, the ferromagnetic mono- and few-layer 2D CrSiTe3 indicated here should enable numerous applications in nano-spintronics.

  12. Imaging the Fano Lattice to Hidden Order Transition in URu2Si2

    SciTech Connect (OSTI)

    Davis, J.C.; Schmidt, A.R.; Hamidian, M.H.; Wahl, P.; Meier, F.; Balatsky, A.V.; Garrett, J.D.; Williams, T.J.; Luke, G.M.

    2010-06-03

    Within a Kondo lattice, the strong hybridization between electrons localized in real space (r-space) and those delocalized in momentum-space (k-space) generates exotic electronic states called 'heavy fermions'. In URu{sub 2}Si{sub 2} these effects begin at temperatures around 55 K but they are suddenly altered by an unidentified electronic phase transition at T{sub o} = 17.5 K. Whether this is conventional ordering of the k-space states, or a change in the hybridization of the r-space states at each U atom, is unknown. Here we use spectroscopic imaging scanning tunnelling microscopy (SI-STM) to image the evolution of URu{sub 2}Si{sub 2} electronic structure simultaneously in r-space and k-space. Above T{sub o}, the 'Fano lattice' electronic structure predicted for Kondo screening of a magnetic lattice is revealed. Below T{sub o}, a partial energy gap without any associated density-wave signatures emerges from this Fano lattice. Heavy-quasiparticle interference imaging within this gap reveals its cause as the rapid splitting below T{sub o} of a light k-space band into two new heavy fermion bands. Thus, the URu{sub 2}Si{sub 2} 'hidden order' state emerges directly from the Fano lattice electronic structure and exhibits characteristics, not of a conventional density wave, but of sudden alterations in both the hybridization at each U atom and the associated heavy fermion states.

  13. Strain-engineered band parameters of graphene-like SiC monolayer

    SciTech Connect (OSTI)

    Behera, Harihar; Mukhopadhyay, Gautam

    2014-10-06

    Using full-potential density functional theory (DFT) calculations we show that the band gap and effective masses of charge carriers in SiC monolayer (ML-SiC) in graphene-like two-dimensional honeycomb structure are tunable by strain engineering. ML-SiC was found to preserve its flat 2D graphene-like structure under compressive strain up to 7%. A transition from indirect-to-direct gap-phase is predicted to occur for a strain value lying within the interval (1.11 %, 1.76%). In both gap-phases band gap decreases with increasing strain, although the rate of decrease is different in the two gap-phases. Effective mass of electrons show a non-linearly decreasing trend with increasing tensile strain in the direct gap-phase. The strain-sensitive properties of ML-SiC, may find applications in future strain-sensors, nanoelectromechanical systems (NEMS) and nano-optomechanical systems (NOMS) and other nano-devices.

  14. Structural consequences of hydrogen intercalation of epitaxial graphene on SiC(0001)

    SciTech Connect (OSTI)

    Emery, Jonathan D. E-mail: bedzyk@northwestern.edu; Johns, James E.; McBriarty, Martin E.; Hersam, Mark C.; Wheeler, Virginia H.; Kurt Gaskill, D.; Detlefs, Blanka; Bedzyk, Michael J. E-mail: bedzyk@northwestern.edu

    2014-10-20

    The intercalation of various atomic species, such as hydrogen, to the interface between epitaxial graphene (EG) and its SiC substrate is known to significantly influence the electronic properties of the graphene overlayers. Here, we use high-resolution X-ray reflectivity to investigate the structural consequences of the hydrogen intercalation process used in the formation of quasi-free-standing (QFS) EG/SiC(0001). We confirm that the interfacial layer is converted to a layer structurally indistinguishable from that of the overlying graphene layers. This newly formed graphene layer becomes decoupled from the SiC substrate and, along with the other graphene layers within the film, is vertically displaced by ?2.1?. The number of total carbon layers is conserved during the process, and we observe no other structural changes such as interlayer intercalation or expansion of the graphene d-spacing. These results clarify the under-determined structure of hydrogen intercalated QFS-EG/SiC(0001) and provide a precise model to inform further fundamental and practical understanding of the system.

  15. Chemical vapor deposition of W-Si-N and W-B-N

    DOE Patents [OSTI]

    Fleming, J.G.; Roherty-Osmun, E.L.; Smith, P.M.; Custer, J.S.; Jones, R.V.; Nicolet, M.; Madar, R.; Bernard, C.

    1999-06-29

    A method of depositing a ternary, refractory based thin film on a substrate by chemical vapor deposition employing precursor sources of tungsten comprising WF[sub 6], either silicon or boron, and nitrogen. The result is a W-Si-N or W-B-N thin film useful for diffusion barrier and micromachining applications. 10 figs.

  16. Local structure order in Pd78Cu6Si16 liquid

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yue, G. Q.; Zhang, Y.; Sun, Y.; Shen, B.; Dong, F.; Wang, Z. Y.; Zhang, R. J.; Zheng, Y. X.; Kramer, M. J.; Wang, S. Y.; et al

    2015-02-05

    The short-range order (SRO) in Pd78Cu6Si16 liquid was studied by high energy x-ray diffraction and ab initio molecular dynamics (MD) simulations. The calculated pair correlation functions at different temperatures agree well with the experimental results. The partial pair correlation functions from ab intio MD simulations indicate that Si atoms prefer to be uniformly distributed while Cu atoms tend to aggregate. By performing structure analysis using Honeycutt-Andersen index, Voronoi tessellation, and atomic cluster alignment method, we show that the icosahedron and face-centered cubic SRO increase upon cooling. The dominant SRO is the Pd-centered Pd9Si2 motif, namely the structure of which motifmore » is similar to the structure of Pd-centered clusters in the Pd9Si2 crystal. The study further confirms the existence of trigonal prism capped with three half-octahedra that is reported as a structural unit in Pd-based amorphous alloys. The majority of Cu-centered clusters are icosahedra, suggesting that the presence of Cu is benefit to promote the glass forming ability.« less

  17. Chemical vapor deposition of W-Si-N and W-B-N

    DOE Patents [OSTI]

    Fleming, James G.; Roherty-Osmun, Elizabeth Lynn; Smith, Paul M.; Custer, Jonathan S.; Jones, Ronald V.; Nicolet, Marc-A.; Madar, Roland; Bernard, Claude

    1999-01-01

    A method of depositing a ternary, refractory based thin film on a substrate by chemical vapor deposition employing precursor sources of tungsten comprising WF.sub.6, either silicon or boron, and nitrogen. The result is a W--Si--N or W--B--N thin film useful for diffusion barrier and micromachining applications.

  18. Investigation of nanocrystalline CdS/Si diode using complex impedance spectroscopy

    SciTech Connect (OSTI)

    El-Gendy, Y.A.; Umm Al-Qura University, University college, Physics Department, Alqunfoza ; Yahia, I.S.; Yakuphanoglu, F.

    2012-11-15

    Highlights: ? CdS/n-Si device was fabricated as a heterostructure. ? AFM was used to examine the structure of CdS/n-Si. ? Complex impedance Z?and Z?were calculated. ? AC conductivity was explained by the power law relation. ? CBH model was used to describe the AC conduction mechanism. -- Abstract: CdS/n-Si device was fabricated via depositing CdS thin film onto pre-cleaned n-silicon substrates. The atomic force microscope was used to examine the crystal size of the deposited films and its roughness. The AC conductivity and the real part of complex impedance Z?as a function of frequency at different temperatures were studied. The AC conductivity dependence of the applied frequency was explained on the basis of the power law relation. The bulk resistance has been calculated at different temperatures from the complex impedance Z?. The temperature dependence of capacitance for CdS/n-Si device at different frequencies was also investigated.

  19. Barocaloric effect in the magnetocaloric prototype Gd5Si2Ge2

    SciTech Connect (OSTI)

    Yuce, Suheyla; Barrio, Maria; Emre, Baris; Stern-Taulats, Enric; Planes, Antoni; Tamarit, Josep-Lluis; Mudryk, Yaroslav; Gschneidner, Karl A.; Pecharsky, Vitalij K.; Manosa, Lluis

    2012-08-16

    We report on calorimetric measurements under hydrostatic pressure that enabled us to determine the barocaloric effect in Gd5Si2Ge2. The values for the entropy change for moderate pressures compare favourably to those corresponding to the magnetocaloric effect in this compound. Entropy data are complemented with direct measurements of the adiabatic pressure-induced temperature change.

  20. Performance of Hydrogenated a-Si:H Solar Cells with Downshifting Coating: Preprint

    SciTech Connect (OSTI)

    Nemeth, B.; Xu, Y.; Wang, H.; Sun, T.; Lee, B. G.; Duda, A.; Wang, Q.

    2011-05-01

    We apply a thin luminescent downshifting (LDS) coating to a hydrogenated amorphous Si (a-Si:H) solar cell and study the mechanism of possible current enhancement. The conversion material used in this study converts wavelengths below 400 nm to a narrow line around 615 nm. This material is coated on the front of the glass of the a-Si:H solar cell with a glass/TCO/p/i/n/Ag superstrate configuration. The initial efficiency of the solar cell without the LDS coating is above 9.0 % with open circuit voltage of 0.84 V. Typically, the spectral response below 400 nm of an a-Si:H solar cell is weaker than that at 615 nm. By converting ultraviolet (UV) light to red light, the solar cell will receive more red photons; therefore, solar cell performance is expected to improve. We observe evidence of downshifting in reflectance spectra. The cell Jsc decreases by 0.13 mA/cm2, and loss mechanisms are identified.

  1. SiC MODIFICATIONS TO MELCOR FOR SEVERE ACCIDENT ANALYSIS APPLICATIONS

    SciTech Connect (OSTI)

    Brad J. Merrill; Shannon M Bragg-Sitton

    2013-09-01

    The Department of Energy (DOE) Office of Nuclear Energy (NE) Light Water Reactor (LWR) Sustainability Program encompasses strategic research focused on improving reactor core economics and safety margins through the development of an advanced fuel cladding system. The Fuels Pathway within this program focuses on fuel system components outside of the fuel pellet, allowing for alteration of the existing zirconium-based clad system through coatings, addition of ceramic sleeves, or complete replacement (e.g. fully ceramic cladding). The DOE-NE Fuel Cycle Research & Development (FCRD) Advanced Fuels Campaign (AFC) is also conducting research on materials for advanced, accident tolerant fuels and cladding for application in operating LWRs. To aide in this assessment, a silicon carbide (SiC) version of the MELCOR code was developed by substituting SiC in place of Zircaloy in MELCORs reactor core oxidation and material property routines. The purpose of this development effort is to provide a numerical capability for estimating the safety advantages of replacing Zr-alloy components in LWRs with SiC components. This modified version of the MELCOR code was applied to the Three Mile Island (TMI-2) plant accident. While the results are considered preliminary, SiC cladding showed a dramatic safety advantage over Zircaloy cladding during this accident.

  2. Intruder negative-parity states of neutron-rich {sup 33}Si

    SciTech Connect (OSTI)

    Wang, Z. M.; Chapman, R.; Liang, X.; Burns, M.; Hodsdon, A.; Keyes, K.; Kumar, V.; Papenberg, A.; Smith, J. F.; Spohr, K. M.; Haas, F.; Bouhelal, M.; Caurier, E.; Curien, D.; Nowacki, F.; Azaiez, F.; Ibrahim, F.; Verney, D.; Behera, B. R.; Corradi, L.

    2010-06-15

    Yrast states in the neutron-rich {sub 14}{sup 33}Si{sub 19} nucleus have been studied using binary grazing reactions produced by the interaction of a 215-MeV beam of {sup 36}S ions with a thin {sup 208}Pb target. An experimental setup that combines the large-acceptance magnetic spectrometer PRISMA and the high-efficiency gamma-ray detection array CLARA was used in the experiment. Four new gamma-ray photopeaks at energies of 971, 1724, 1772, and 2655 keV were observed and assigned to the {sup 33}Si level scheme. The experimental level scheme is compared with the results of 1(Planck constant/2pi)omega p-sd-pf large-scale shell-model calculations using the recently developed PSDPFB effective interaction; good agreement is obtained. The structure of the populated states of {sup 33}Si is discussed within the context of an odd neutron coupled to states of the {sup 32}Si core.

  3. FeAl and Mo-Si-B Intermetallic Coatings Prepared by Thermal Spraying

    SciTech Connect (OSTI)

    Totemeier, T.C.; Wright, R.N.; Swank, W.D.

    2003-04-22

    FeAl and Mo-Si-B intermetallic coatings for elevated temperature environmental resistance were prepared using high-velocity oxy-fuel (HVOF) and air plasma spray (APS) techniques. For both coating types, the effect of coating parameters (spray particle velocity and temperature) on the microstructure and physical properties of the coatings was assessed. Fe-24Al (wt.%) coatings were prepared using HVOF thermal spraying at spray particle velocities varying from 540 m/s to 700 m/s. Mo-13.4Si-2.6B coatings were prepared using APS at particle velocities of 180 and 350 m/s. Residual stresses in the HVOF FeAl coatings were compressive, while stresses in the APS Mo-Si-B coatings were tensile. In both cases, residual stresses became more compressive with increasing spray particle velocity due to increased peening imparted by the spray particles. The hardness and elastic moduli of FeAl coatings also increased with increasing particle velocity, again due to an increased peening effect. For Mo-Si-B coatings, plasma spraying at 180 m/s resulted in significant oxidation of the spray particles and conversion of the T1 phase into amorphous silica and {alpha}-Mo. The T1 phase was retained after spraying at 350 m/s.

  4. Lattice-registered growth of GaSb on Si (211) with molecular beam epitaxy

    SciTech Connect (OSTI)

    Hosseini Vajargah, S.; Botton, G. A.; Ghanad-Tavakoli, S.; Preston, J. S.; Kleiman, R. N.

    2012-11-01

    A GaSb film was grown on a Si(211) substrate using molecular beam epitaxy indicating full lattice relaxation as well as full lattice registration and dislocation-free growth in the plane perpendicular to the [01 - 1]-direction. Heteroepitaxy of GaSb on a Si(211) substrate is dominated by numerous first order and multiple higher order micro-twins. The atomic-resolved structural study of GaSb films by high-angle annular dark-field scanning transmission electron microscopy reveals that slight tilt, along with twinning, favors the lattice registry to Si(211) substrates. Preferential bonding of impinging Ga and Sb atoms at the interface due to two distinctive bonding sites on the Si(211) surface enables growth that is sublattice-ordered and free of anti-phase boundaries. The role of the substrate orientation on the strain distribution of GaSb epilayers is further elucidated by investigating the local change in the lattice parameter using the geometric phase analysis method and hence effectiveness of the lattice tilting in reducing the interfacial strain was confirmed further.

  5. Report on status of execution of SiC step document

    SciTech Connect (OSTI)

    Katoh, Yutai; Terrani, Kurt A.

    2015-02-01

    Advanced fuel claddings made entirely or mainly of silicon carbide (SiC) ceramics and/or composites are considered very attractive elements of the accident-tolerant fuels for the light water reactors. In order to translate the promise of SiC composite materials into a reliable fuel cladding, a coordinated program of component level design and materials development must be carried out with many key feasibility issues addressed a-priori to inform the process. With the primary objective of developing a draft blueprint of a technical program that addresses the critical feasibility issues; assesses design and performance issues related with manufacturing, operating, and off-normal events; and advances the technological readiness levels in essential technology elements, a draft plan for the Systematic Technology Evaluation Program for SiC/SiC Composite Accident-Tolerant LWR Fuel Cladding and Core Structures was developed in the FY-14 Advanced Fuels Campaign of the U.S. Department of Energys Fuel Cycles Research and Development Program. This document summarizes the status of execution of the technical plan within the activities at the Oak Ridge National Laboratory.

  6. Evaluation of Li2MnSiO4 Cathode | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    11 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation PDF icon es018_belharouak_2011_p.pdf More Documents & Publications Search for High Energy Density Cathode Materials Evaluation of Li2MnSiO4 Cathode Design of Safer High-Energy Density Materials for Lithium-Ion Cells

  7. Evaluation of Li2MnSiO4 Cathode | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    09 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. PDF icon esp_18_belharouak.pdf More Documents & Publications Search for High Energy Density Cathode Materials Evaluation of Li2MnSiO4 Cathode Vehicle Technologies Office Merit Review 2014: High-Capacity Polyanion Cathodes

  8. Development of SiC Large Tapered Crystal Growth | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    2 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting PDF icon ape027_neudeck_2012_o.pdf More Documents & Publications Vehicle Technologies Office Merit Review 2014: Development of SiC Large Tapered

  9. Facet-selective nucleation and conformal epitaxy of Ge shells on Si nanowires

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nguyen, Binh -Minh; Swartzentruber, Brian; Ro, Yun Goo; Dayeh, Shadi A.

    2015-10-08

    Knowledge of nanoscale heteroepitaxy is continually evolving as advances in material synthesis reveal new mechanisms that have not been theoretically predicted and are different than what is known about planar structures. In addition to a wide range of potential applications, core/shell nanowire structures offer a useful template to investigate heteroepitaxy at the atomistic scale. We show that the growth of a Ge shell on a Si core can be tuned from the theoretically predicted island growth mode to a conformal, crystalline, and smooth shell by careful adjustment of growth parameters in a narrow growth window that has not been exploredmore » before. In the latter growth mode, Ge adatoms preferentially nucleate islands on the {113} facets of the Si core, which outgrow over the {220} facets. Islands on the low-energy {111} facets appear to have a nucleation delay compared to the {113} islands; however, they eventually coalesce to form a crystalline conformal shell. As a result, synthesis of epitaxial and conformal Si/Ge/Si core/multishell structures enables us to fabricate unique cylindrical ring nanowire field-effect transistors, which we demonstrate to have steeper on/off characteristics than conventional core/shell nanowire transistors.« less

  10. Improvement of thermal stability of amorphous CoFeSiB thin films

    SciTech Connect (OSTI)

    Jimbo, M. Shimizu, T.; Fujiwara, Y.

    2015-05-07

    The excellent soft magnetic properties of amorphous (a-) CoFeSiB films make it suited for use in the yoke of granular-in-gap sensors, but only if their thermal stability can be improved. To this end, this study investigated the effects of adding small amounts of other metals on the magnetic and structural properties of a-CoFeSiB films. It was found that adding metals with relatively large atomic radii is an effective way to increase thermal stability, with both Ta and Hf showing good thermal stability after annealing at temperatures of 473 to 573?K. Indeed, a -(CoFeSiB){sub 96.2}Hf{sub 3.8} film was found to maintain its initial coercivity of 0.2?Oe without very little decrease in magnetization after annealing at 623?K. Furthermore, even after annealing at 673?K a -(CoFeSiB){sub 93.0}Hf{sub 7.0} film still had a relatively low coercivity of approximately 0.5?Oe.

  11. Microstructure and tribological performance of nanocomposite Ti-Si-C-N coatings deposited using hexamethyldisilazane precursor

    SciTech Connect (OSTI)

    Wei Ronghua; Rincon, Christopher; Langa, Edward; Yang Qi

    2010-09-15

    Thick nanocomposite Ti-Si-C-N coatings (20-30 {mu}m) were deposited on Ti-6Al-4V substrate by magnetron sputtering of Ti in a gas mixture of Ar, N{sub 2}, and hexamethyldisilazane (HMDSN) under various deposition conditions. Microstructure and composition of the coatings were studied using scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy, while the mechanical and tribological properties of these coatings were studied using Rc indentation, and micro- and nanoindentations, solid particle erosion testing, and ball-on-disk wear testing. It has been observed that the Si concentration of these coatings is varied from 0% (TiN) to 15% (Ti-Si-C-N), while the structure of these coatings is similar to the nanocomposite Ti-Si-N coatings and consists of nanocrystalline B1 structured Ti(C,N) in an amorphous matrix of SiC{sub x}N{sub y} with the grain size of 5->100 nm, depending on the coating preparation process. These coatings exhibit excellent adhesion when subjected to Rc indentation tests. The microhardness of these coatings varies from 1200 to 3400 HV25, while the nanohardness varies from 10 to 26 GPa. Both the microhardness and nanohardness are slightly lower than those of similar coatings prepared using trimethylsilane. However, the erosion test using a microsand erosion tester at both 30 deg. and 90 deg. incident angles shows that these coatings have very high erosion resistance and up to a few hundred times of improvement has been observed. These coatings also exhibit very high resistance to sliding wear with a low coefficient of friction of about 0.2 in dry sliding. There are a few advantages of using the HMDSN precursor to prepare the Ti-Si-C-N coatings over conventional magnetron sputtered deposition of Ti-Si-N coatings including composition uniformity, precursor handling safety, and high deposition rate. The coatings can be applied to protect gas turbine compressor blades from solid particle erosion and steam turbine blades from liquid droplet erosion, as well as other mechanical components that experience severe abrasion. These coatings may also be used in areas where both high wear resistance and low friction are required.

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

    SciTech Connect (OSTI)

    Fiameni, S.; Battiston, S.; Boldrini, S.; Famengo, A.; Agresti, F.; Barison, S.; Fabrizio, M.

    2012-09-15

    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.

  13. Annealing temperature and barrier thickness effect on the structural and optical properties of silicon nanocrystals/SiO₂ superlattices

    SciTech Connect (OSTI)

    López-Vidrier, J. Hernández, S.; López-Conesa, L.; Peiró, F.; Garrido, B.; Hiller, D.; Gutsch, S.; Zacharias, M.; Estradé, S.

    2014-10-07

    The effect of the annealing temperature and the SiO₂ barrier thickness of silicon nanocrystal (NC)/SiO₂ superlattices (SLs) on their structural and optical properties is investigated. Energy-filtered transmission electron microscopy (TEM) revealed that the SL structure is maintained for annealing temperatures up to 1150 °C, with no variation on the nanostructure morphology for different SiO₂ barrier thicknesses. Nevertheless, annealing temperatures as high as 1250 °C promote diffusion of Si atoms into the SiO₂ barrier layers, which produces larger Si NCs and the loss of the NC size control expected from the SL approach. Complementary Raman scattering measurements corroborated these results for all the SiO₂ and Si-rich oxynitride layer thicknesses. In addition, we observed an increasing crystalline fraction up to 1250 °C, which is related to a decreasing contribution of the suboxide transition layer between Si NCs and the SiO₂ matrix due to the formation of larger NCs. Finally, photoluminescence measurements revealed that the emission of the superlattices exhibits a Gaussian-like lineshape with a maximum intensity after annealing at 1150 °C, indicating a high crystalline degree in good agreement with Raman results. Samples submitted to higher annealing temperatures display a progressive emission broadening, together with an increase in the central emission wavelength. Both effects are related to a progressive broadening of the size distribution with a larger mean size, in agreement with TEM observations. On the other hand, whereas the morphology of the Si NCs is unaffected by the SiO₂ barrier thickness, the emission properties are slightly modified. These observed modifications in the emission lineshape allow monitoring the precipitation process of Si NCs in a direct non-destructive way. All these experimental results evidence that an annealing temperature of 1150 °C and 1-nm SiO₂ barrier can be reached whilst preserving the SL structure, being thus the optimal structural SL parameters for their use in optoelectronics.

  14. Morphology and chemical termination of HF-etched Si{sub 3}N{sub 4} surfaces

    SciTech Connect (OSTI)

    Liu, Li-Hong; Debenedetti, William J. I.; Peixoto, Tatiana; Gokalp, Sumeyra; Shafiq, Natis; Veyan, Jean-François; Chabal, Yves J.; Michalak, David J.; Hourani, Rami

    2014-12-29

    Several reports on the chemical termination of silicon nitride films after HF etching, an important process in the microelectronics industry, are inconsistent claiming N-H{sub x}, Si-H, or fluorine termination. An investigation combining infrared and x-ray photoelectron spectroscopies with atomic force and scanning electron microscopy imaging reveals that under some processing conditions, salt microcrystals are formed and stabilized on the surface, resulting from products of Si{sub 3}N{sub 4} etching. Rinsing in deionized water immediately after HF etching for at least 30 s avoids such deposition and yields a smooth surface without evidence of Si-H termination. Instead, fluorine and oxygen are found to terminate a sizeable fraction of the surface in the form of Si-F and possibly Si-OH bonds. The relatively unique fluorine termination is remarkably stable in both air and water and could lead to further chemical functionalization pathways.

  15. The First-cycle Electrochemical Lithiation of Crystalline Ge Dopant and Orientation Dependence, and Comparison with Si

    SciTech Connect (OSTI)

    Chan, Maria K.Y.; Long, Brandon R.; Gewirth, Andrew A.; Greeley, Jeffrey P.

    2011-12-15

    We use first principles Density Functional Theory (DFT), cyclic voltammetry (CV), and Raman spectroscopy to investigate the first-cycle electrochemical lithiation of Ge in comparison with Si both high-capacity anode materials for Li ion batteries. DFT shows a significant difference in the dilute solubility of Li in Si and Ge, despite similarities in their chemical and physical properties. We attribute this difference to electronic, as opposed to elastic, effects. CV and Raman data reveal little dopant dependence in the lithiation onset voltages in Ge, unlike in Si, due to a smaller energy difference between dilute Li insertion in p-type Ge and bulk germanide formation than the corresponding difference in Si. Finally, we show that there is no orientation dependence in lithiation onset voltages in Ge. We conclude that approaches other than microstructuring are needed to fabricate effective electrodes able to take advantage of the higher rate capability of Ge compared to that of Si.

  16. Single-Crystalline B12As2 on m-plane (1100) 15R-SiC

    SciTech Connect (OSTI)

    Chen,H.; Wang, G.; Dudley, M.; Xu, Z.; Edgar, J.; Batten, T.; Kuball, M.; Zhang, L.; Zhu, Y.

    2008-01-01

    Single crystal, heteroepitaxial growth of icosahedral B12As2 (IBA, a boride semiconductor) on m-plane 15R-SiC is demonstrated. Previous studies of IBA on other substrates, i.e., (111)Si and (0001)6H-SiC, produced polycrystalline and twinned epilayers. In contrast, single-crystalline and untwinned IBA was achieved on m-plane 15R-SiC. Synchrotron white beam x-ray topography, Raman spectroscopy, and high resolution transmission electron microscopy confirm the high quality of the films. High quality growth is shown to be mediated by ordered nucleation of IBA on (474) substrate facets. This work demonstrates that m-plane 15R-SiC is a good substrate choice to grow high-quality untwinned IBA epilayers for future device applications.

  17. Mesoscale Origin of the Enhanced Cycling-Stability of the Si-Conductive Polymer Anode for Li-ion Batteries

    SciTech Connect (OSTI)

    Gu, Meng; Xiao, Xingcheng; Liu, Gao; Thevuthasan, Suntharampillai; Baer, Donald R.; Zhang, Jiguang; Liu, Jun; Browning, Nigel D.; Wang, Chong M.

    2014-01-14

    Electrode used in lithium-ion battery is invariably a composite of multifunctional components. The performance of the electrode is controlled by the interactive function of all components at mesoscale. Fundamental understanding of mesoscale phenomenon sets the basis for innovative designing of new materials. Here we report the achievement and origin of a significant performance enhancement of electrode for lithium ion batteries based on Si nanoparticles wrapped with conductive polymer. This new material is in marked contrast with conventional material, which exhibit fast capacity fade. In-situ TEM unveils that the enhanced cycling stability of the conductive polymer-Si composite is associated with mesoscale concordant function of Si nanoparticles and the conductive polymer. Reversible accommodation of the volume changes of Si by the conductive polymer allows good electrical contact between all the particles during the cycling process. In contrast, the failure of the conventional Si-electrode is probed to be the inadequate electrical contact.

  18. SiD Linear Collider Detector R&D, DOE Final Report

    SciTech Connect (OSTI)

    Brau, James E.; Demarteau, Marcel

    2015-05-15

    The Department of Energy’s Office of High Energy Physics supported the SiD university detector R&D projects in FY10, FY11, and FY12 with no-cost extensions through February, 2015. The R&D projects were designed to advance the SiD capabilities to address the fundamental questions of particle physics at the International Linear Collider (ILC): • What is the mechanism responsible for electroweak symmetry breaking and the generation of mass? • How do the forces unify? • Does the structure of space-time at small distances show evidence for extra dimensions? • What are the connections between the fundamental particles and forces and cosmology? Silicon detectors are used extensively in SiD and are well-matched to the challenges presented by ILC physics and the ILC machine environment. They are fast, robust against machine-induced background, and capable of very fine segmentation. SiD is based on silicon tracking and silicon-tungsten sampling calorimetry, complemented by powerful pixel vertex detection, and outer hadronic calorimetry and muon detection. Radiation hard forward detectors which can be read out pulse by pulse are required. Advanced calorimetry based on a particle flow algorithm (PFA) provides excellent jet energy resolution. The 5 Tesla solenoid is outside the calorimeter to improve energy resolution. PFA calorimetry requires fine granularity for both electromagnetic and hadronic calorimeters, leading naturally to finely segmented silicon-tungsten electromagnetic calorimetry. Since silicon-tungsten calorimetry is expensive, the detector architecture is compact. Precise tracking is achieved with the large magnetic field and high precision silicon microstrips. An ancillary benefit of the large magnetic field is better control of the e⁺e⁻ pair backgrounds, permitting a smaller radius beampipe and improved impact parameter resolution. Finally, SiD is designed with a cost constraint in mind. Significant advances and new capabilities have been made and are described in this report.

  19. Self-organization during growth of ZrN/SiN{sub x} multilayers by epitaxial lateral overgrowth

    SciTech Connect (OSTI)

    Fallqvist, A.; Fager, H.; Hultman, L.; Persson, P. O. .; Ghafoor, N.

    2013-12-14

    ZrN/SiN{sub x} nanoscale multilayers were deposited on ZrN seed layers grown on top of MgO(001) substrates by dc magnetron sputtering with a constant ZrN thickness of 40 and with an intended SiN{sub x} thickness of 2, 4, 6, 8, and 15 at a substrate temperature of 800 C and 6 at 500 C. The films were investigated by X-ray diffraction, high-resolution scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy. The investigations show that the SiN{sub x} is amorphous and that the ZrN layers are crystalline. Growth of epitaxial cubic SiN{sub x}known to take place on TiN(001)on ZrN(001) is excluded to the monolayer resolution of this study. During the course of SiN{sub x} deposition, the material segregates to form surface precipitates in discontinuous layers for SiN{sub x} thicknesses ?6 that coalesce into continuous layers for 8 and 15 thickness at 800 C, and for 6 at 500 C. The SiN{sub x} precipitates are aligned vertically. The ZrN layers in turn grow by epitaxial lateral overgrowth on the discontinuous SiN{sub x} in samples deposited at 800 C with up to 6 thick SiN{sub x} layers. Effectively a self-organized nanostructure can be grown consisting of strings of 13 nm large SiN{sub x} precipitates along apparent column boundaries in the epitaxial ZrN.

  20. Electron density distribution and disordered crystal structure of 15R-SiAlON, SiAl{sub 4}O{sub 2}N{sub 4}

    SciTech Connect (OSTI)

    Banno, Hiroki; Hanai, Takaaki; Asaka, Toru; Kimoto, Koji; Fukuda, Koichiro

    2014-03-15

    The crystal structure of SiAl{sub 4}O{sub 2}N{sub 4} was characterized by laboratory X-ray powder diffraction (CuK?{sub 1}). The title compound is trigonal with space group R3-bar m. The hexagonal unit-cell dimensions (Z=3) are a=0.301332(3) nm, c=4.18616(4) nm and V=0.3291825(5) nm{sup 3}. The initial structural model was successfully derived by the charge-flipping method and further refined by the Rietveld method. The final structural model showed the positional disordering of one of the three (Si,Al) sites. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were R{sub wp}=5.05%, S (=R{sub wp}/R{sub e})=1.21, R{sub p}=3.77%, R{sub B}=1.29% and R{sub F}=1.01%. The disordered crystal structure was successfully described by overlapping three types of domains with ordered atom arrangements. The distribution of atomic positions in one of the three types of domains can be achieved in the space group R3-bar m. The atom arrangements in the other two types of domains are noncentrosymmetrical with the space group R3m. These two structural configurations are related by the pseudo-symmetry inversion. -- Graphical abstract: A bird's eye view of electron densities up to 75.3% (0.133 nm{sup ?3}) of the maximum on the plane parallel to (110) with the corresponding atomic arrangements of SiAl{sub 4}O{sub 2}N{sub 4}. Highlights: Crystal structure of SiAl{sub 4}O{sub 2}N{sub 4} is determined by laboratory X-ray powder diffraction. The atom arrangements are represented by the split-atom model. The maximum-entropy method-based pattern fitting method is used to confirm the validity of the model. The disordered structure is described by overlapping three types of domains with ordered atom arrangements.

  1. Composite Synthesis Methodology Development: Nanocrvstalline SiC and Ti3SiC2 Alloys for Reactory Materials Outline of initial synthesis capabilities M4CT-13PN0405034

    SciTech Connect (OSTI)

    Henager, Charles H.; Alvine, Kyle J.; Shin, Yongsoon; Jiang, Weilin; Nguyen, Ba Nghiep

    2013-03-29

    We have identified three initial preceramic polymers to help produce the SiC-based alloys for this project and have developed simple processing steps to make SiC-based alloy ceramics. The use of unfilled SMP-10 (Polycarbosilane) or SMP-877 (Methyl-Polycarbosilane) is not feasible due to the large mass losses that occur during pyrolysis. The pre-gelling steps below save time when those two polymers are filled with powders. The use of SL-MS30 provides us with a SiC-filled polymer that can be used to test out the CNT mats without further complications due to other powders.

  2. Fabrication of Sr silicate buffer layer on Si(100) substrate by pulsed laser deposition using a SrO target

    SciTech Connect (OSTI)

    Imanaka, Atsuhiro; Sasaki, Tsubasa; Hotta, Yasushi Satoh, Shin-ichi

    2014-09-01

    The authors fabricated 2??1 Sr-reconstructed Si(100) substrates using thin SrO layers, and used them to direct growth of crystalline perovskite oxide on Si. The SrO layers used to reconstruct the Si(100) substrates were grown by pulsed laser deposition from a SrO single crystal target, followed by postdeposition-annealing (PDA) of the SrO/Si(100) structure. In situ observations of reflective high-energy electron diffraction during PDA confirmed a 2??1 reconstruction of the Si surface and x-ray photoemission spectroscopy of the annealed samples confirmed the existence of Sr atoms in a silicate phase, which indicated that a 2??1 Sr-reconstructed Si surface was achieved. The optimal fabrication conditions were annealing at 720?C for 1?min and an equivalent SrO layer thickness (ML{sub eq}) of 2.5 ML{sub eq}. The temperature condition was very narrow, at 720??20?C, for an acceptable product. Subsequently, the authors demonstrated the growth of crystalline SrTiO{sub 3} films on the 2??1 Sr-reconstructed Si(100) surfaces.

  3. Passivation of Oxide Layers on 4H-SiC Using Sequential Anneals in Nitric Oxide and Hydrogen

    SciTech Connect (OSTI)

    Williams, J. R.; Isaacs-Smith, T.; Wang, S.; Ahyi, C.; Lawless, R. M.; Tin, C. C.; Dhar, S.; Franceschetti, Alberto G; Pantelides, Sokrates T; Feldman, Leonard C; Chung, G.; Chisholm, Matthew F

    2004-01-01

    The interface passivation process based on post-oxidation, high temperature anneals in nitric oxide (NO) is well established for SiO{sub 2} on (0001) 4H-SiC. The NO process results in an order of magnitude or more reduction in the interface state density near the 4H conduction band edge. However, trap densities are still high compared to those measured for Si/SiO{sub 2} passivated with post-oxidation anneals in hydrogen. Herein, we report the results of studies for 4H-SiC/SiO{sub 2} undertaken to determine the effects of additional passivation anneals in hydrogen when these anneals are carried out following a standard NO anneal. After NO passivation and Pt deposition to form gate contacts, post-metallization anneals in hydrogen further reduced the trap density from approximately 1.5 x 10{sup 12} cm{sup -2}eV{sup -1} to about 6 x 10{sup 11} cm{sup -2}eV{sup -1} at a trap energy of 0.1 eV below the band edge for dry thermal oxides on both (0001) and (11-20) 4H-SiC.

  4. Low dark current and high speed ZnO metalsemiconductormetal photodetector on SiO{sub 2}/Si substrate

    SciTech Connect (OSTI)

    al??kan, Deniz; Btn, Bayram; ak?r, M. Cihan; zcan, ?adan; zbay, Ekmel

    2014-10-20

    ZnO thin films are deposited by radio-frequency magnetron sputtering on thermally grown SiO{sub 2} on Si substrates. Pt/Au contacts are fabricated by standard photolithography and lift-off in order to form a metal-semiconductor-metal (MSM) photodetector. The dark current of the photodetector is measured as 1?pA at 100?V bias, corresponding to 100?pA/cm{sup 2} current density. Spectral photoresponse measurement showed the usual spectral behavior and 0.35?A/W responsivity at a 100?V bias. The rise and fall times for the photocurrent are measured as 22 ps and 8?ns, respectively, which are the lowest values to date. Scanning electron microscope image shows high aspect ratio and dense grains indicating high surface area. Low dark current density and high speed response are attributed to high number of recombination centers due to film morphology, deducing from photoluminescence measurements. These results show that as deposited ZnO thin film MSM photodetectors can be used for the applications needed for low light level detection and fast operation.

  5. Simultaneous catalyst deposition and growth of aligned carbon nanotubes on SiO{sub 2}/Si substrates by radio frequency magnetron sputtering

    SciTech Connect (OSTI)

    Scalese, S.; Scuderi, V.; Privitera, V.; Pennisi, A.; Simone, F.

    2007-12-01

    Radio frequency magnetron sputtering has been used for the synthesis of aligned carbon nanotubes (CNTs) on a SiO{sub 2}/Si substrate, with simultaneous in situ catalyst deposition. This method allows the use of substrates without the need of a surface predeposition of catalytic particles. In particular, among the metals considered, we observed the formation of CNTs using W or Ni as catalysts. Only in the case of Ni did we find that the CNTs are aligned along the target-substrate direction, unlike the randomly oriented CNTs observed when W was used as catalyst. Scanning and transmission electron microscopies show that the catalytic Ni nanoparticle is found mostly on the tip of the obtained bamboolike CNTs, while W nanoparticles are encapsulated inside hollow nanotubes, at different points along their length. We ascribe not only the observed structural differences to the size of the W and Ni particles but also to a different diffusion behavior of C in the two kinds of metallic clusters.

  6. Radiation induced cavity formation and gold precipitation at the interfaces of a ZrO2/SiO2/Si heterostructure

    SciTech Connect (OSTI)

    Edmondson, Philip D; Wang, Chongmin; Zhu, Zihua; Namavar, Fereydoon; Weber, William J; Zhang, Yanwen

    2011-01-01

    Thin films nano-crystalline zirconia of ~ 300 nm thick were deposited on Si substrate, and the samples were irradiated with 2 MeV Au+ ions at temperatures of 160 and 400 K, up to fluences of 35 displacements per atom. The films were then studied using glancing incidence x-ray diffraction, Rutherford backscattering, secondary ion mass spectroscopy and transmission electron microscopy. During the irradiation, cavities were observed to form at the zirconia/silicon interface. The morphology of the cavities was found to be related to the damage state of the underlying Si substrate. Elongated cavities were observed when the substrate is heavily damaged but not amorphized; however, when the substrate is rendered amorphous, the cavities become spherical. As the ion dose increases, the cavities then act as efficient gettering sites for the Au. The concentration of oxygen within the cavities determines the order in which the cavities getter. Following complete filling of the cavities, the interface acts as the secondary gettering site for the Au. The Au precipitates are determined to be elemental in nature due to the high binding free energy for the formation of Au-silicides.

  7. In-situ high resolution transmission electron microscopy observation of silicon nanocrystal nucleation in a SiO{sub 2} bilayered matrix

    SciTech Connect (OSTI)

    Yang, T. C.-J. Wu, L.; Lin, Z.; Jia, X.; Puthen-Veettil, B.; Zhang, T.; Conibeer, G.; Perez-Wurfl, I.; Kauffmann, Y.; Rothschild, A.

    2014-08-04

    Solid-state nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix was observed at temperatures as low as 450?C. This was achieved by aberration corrected high-resolution transmission electron microscopy (HRTEM) with real-time in-situ heating up to 600?C. This technique is a valuable characterization tool especially with the recent interest in Si nanostructures for light emitting devices, non-volatile memories, and third-generation photovoltaics which all typically require a heating step in their fabrication. The control of size, shape, and distribution of the Si nanocrystals are critical for these applications. This experimental study involves in-situ observation of the nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix fabricated through radio frequency co-sputtering. The results show that the shapes of Si nanocrystals in amorphous SiO{sub 2} bilayered matrices are irregular and not spherical, in contrast to many claims in the literature. Furthermore, the Si nanocrystals are well confined within their layers by the amorphous SiO{sub 2}. This study demonstrates the potential of in-situ HRTEM as a tool to observe the real time nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix. Furthermore, ideas for improvements on this in-situ heating HRTEM technique are discussed.

  8. High-Rate Fabrication of a-Si-Based Thin-Film Solar Cells Using Large-Area VHF PECVD Processes

    SciTech Connect (OSTI)

    Deng, Xunming; Fan, Qi Hua

    2011-12-31

    The University of Toledo (UT), working in concert with its a-Si-based PV industry partner Xunlight Corporation (Xunlight), has conducted a comprehensive study to develop a large-area (3ft x 3ft) VHF PECVD system for high rate uniform fabrication of silicon absorber layers, and the large-area VHF PECVD processes to achieve high performance a-Si/a-SiGe or a-Si/nc-Si tandem junction solar cells during the period of July 1, 2008 to Dec. 31, 2011, under DOE Award No. DE-FG36-08GO18073. The project had two primary goals: (i) to develop and improve a large area (3 ft 3 ft) VHF PECVD system for high rate fabrication of > = 8 /s a-Si and >= 20 /s nc-Si or 4 /s a-SiGe absorber layers with high uniformity in film thicknesses and in material structures. (ii) to develop and optimize the large-area VHF PECVD processes to achieve high-performance a-Si/nc-Si or a-Si/a-SiGe tandem-junction solar cells with >= 10% stable efficiency. Our work has met the goals and is summarized in Accomplishments versus goals and objectives.

  9. The electronic and optical properties of Eu/Si-codoped anatase TiO{sub 2} photocatalyst

    SciTech Connect (OSTI)

    Lin Yanming; Jiang Zhenyi; Zhang Xiaodong; Hu Xiaoyun; Fan Jun

    2012-03-05

    The electronic and optical properties of Eu/Si-codoped anatase TiO{sub 2} are investigated using the density functional theory. The calculated results show that the synergistic effects of Eu/Si codoping can effectively extend the optical absorption edge, which can lead to higher visible-light photocatalytic activities than pure anatase TiO{sub 2}. To verify the reliability of our calculated results, nanocrystalline Eu/Si-codoped TiO{sub 2} is prepared by a sol-gel-solvothermal method, and the experimental results also indicate that the codoping sample exhibits better absorption performance and higher photocatalytic activities than pure TiO{sub 2}.

  10. Facile synthesis of highly stable a-Si by ion implantation of low-keV H isotopes

    SciTech Connect (OSTI)

    Moutanabbir, O.; Scholz, R.; Goesele, U.; Terreault, B.

    2009-06-15

    It is experimentally shown that silicon is 'easily' amorphized by low-keV H ions at the relatively high temperature of 150 K and for an ion fluence equivalent to <1 DPA (displacement per atom). The a-Si layer is much more stable against recrystallization than a-Si produced by other ions and more stable against chemical modification than c-Si that is H-implanted at room temperature. These results are unexplained by the current atomic collision theory, including molecular-dynamics simulations, but they demonstrate the stabilizing effect of dangling bond passivation by H atoms in postulated, metastable, amorphous droplets.

  11. Efficiency calculations of thin-film GaAs solar cells on Si substrates

    SciTech Connect (OSTI)

    Yamaguchi, M.; Amano, C.

    1985-11-01

    Dislocation effect upon the efficiency of single-crystal thin-film AlGaAs-GaAs heteroface solar cells on Si substrates is analyzed. Solar-cell properties are calculated based on a simple model; in the model, dislocations act as recombination centers to reduce the minority-carrier diffusion length in each layer and increase the space-charge layer recombination current. Numerical analysis is also carried out to optimize thin-film AlGaAs-GaAs heteroface solar-cell structures. The fabrication of thin-film AlGaAs-GaAs heteroface solar cells with a practical efficiency larger than 18% on Si substrates appears possible if the dislocation density in the thin-film GaAs layer is less than 10/sup 6/ cm/sup -2/.

  12. Analysis of soft x-ray/VUV transmission characteristics of Si and Al filters

    SciTech Connect (OSTI)

    Joseph, Aby; Modi, Mohammed H.; Singh, Amol; Gupta, R. K.; Lodha, G. S.

    2013-02-05

    Ultrathin filters of Al (1500A) and Si (1200A) should exhibit more than 65% transmission above their Labsorption edges in the soft x-ray/vacuum ultra violet region(Si L-edge: 124 A and Al L-edge: 170 A). However, the measured transmission characteristics of these filters showed {approx}40% transmission. The transmission measurements of these filters were carried at the reflectivity beamline of Indus-1 synchrotron source out over a large wavelength range of 120-360A. In order to understand the measured transmission performance a detailed model fitting is performed using the Paratt formalism. It is found that the oxidation of the surface region of the filters is responsible for the reduced transmission performance. Effects of higher harmonics of the toroidal grating monochromator are also considered in the data analysis.

  13. Role of thermal processes in dewetting of epitaxial Ag(111) film on Si(111)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sanders, Charlotte E.; Zhang, Chendong D.; Kellogg, Gary L.; Shih, Chih-Kang

    2014-08-01

    Epitaxially grown silver (Ag) film on silicon (Si) is an optimal plasmonic device platform, but its technological utility has been limited by its tendency to dewet rapidly under ambient conditions (standard temperature and pressure). The mechanisms driving this dewetting have not heretofore been determined. In our study, scanning probe microscopy and low-energy electron microscopy are used to compare the morphological evolution of epitaxial Ag(111)/Si(111) under ambient conditions with that of similarly prepared films heated under ultra-high vacuum (UHV) conditions. Furthermore, dewetting is seen to be initiated with the formation of pinholes, which might function to relieve strain in the film.more » We find that in the UHV environment, dewetting is determined by thermal processes, and while under ambient conditions, thermal processes are not required. Finally, we conclude that dewetting in ambient conditions is triggered by some chemical process, most likely oxidation.« less

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

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2013-10-01

    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.

  15. Defect-Band Emission Photoluminescence Imaging on Multi-Crystalline Si Solar Cells: Preprint

    SciTech Connect (OSTI)

    Yan, F.; Johnston, S.; Zaunbrecher, K.; Al-Jassim, M.; Sidelkheir, O.; Blosse, A.

    2011-07-01

    Defect-band photoluminescence (PL) imaging with an InGaAs camera was applied to multicrystalline silicon (mc-Si) wafers, which were taken from different heights of different Si bricks. Neighboring wafers were picked at six different processing steps, from as-cut to post-metallization. By using different cut-off filters, we were able to separate the band-to-band emission images from the defect-band emission images. On the defect-band emission images, the bright regions that originate from the grain boundaries and defect clusters were extracted from the PL images. The area fraction percentage of these regions at various processing stages shows a correlation with the final cell electrical parameters.

  16. Fabrication and Evaluation of a High Performance SiC Inverter for Wireless Power Transfer Applications

    SciTech Connect (OSTI)

    Onar, Omer C; Campbell, Steven L; Ning, Puqi; Miller, John M; Liang, Zhenxian

    2013-01-01

    In this study, a high power density SiC high efficiency wireless power transfer converter system via inductive coupling has been designed and developed. The detailed power module design, cooling system design and power stage development are presented. The successful operation of rated power converter system demonstrates the feasible wireless charging plan. One of the most important part of this study is the wind bandgap devices packaged at the Oak Ridge National Laboratory (ORNL) using the in-house packaging technologies by employing the bare SiC dies acquired from CREE, which are rated at 50 A / 1200 V each. These packaged devices are also inhouse tested and characterized using ORNL s Device Characterization Facility. The successful operation of the proposed inverter is experimentally verified and the efficiency and operational characteristics of the inverter are also revealed.

  17. The spin-dependent transport of Co-encapsulated Si nanotubes contacted with Cu electrodes

    SciTech Connect (OSTI)

    Guo, Yan-Dong; Yan, Xiao-Hong; Xiao, Yang

    2014-02-10

    Unlike carbon nanotubes, silicon ones are hard to form. However, they could be stabilized by metal-encapsulation. Using first-principles calculations, we investigate the spin-dependent electronic transport of Co-encapsulated Si nanotubes, which are contacted with Cu electrodes. For the finite tubes, as the tube-length increases, the transmission changes from spin-unpolarized to spin-polarized. Further analysis shows that, not only the screening of electrodes on Co's magnetism but also the spin-asymmetric Co-Co interactions are the physical mechanisms. As Cu and Si are the fundamental elements in semiconductor industry, our results may throw light on the development of silicon-based spintronic devices.

  18. Defect reaction network in Si-doped InAs. Numerical predictions.

    SciTech Connect (OSTI)

    Schultz, Peter A.

    2015-05-01

    This Report characterizes the defects in the def ect reaction network in silicon - doped, n - type InAs predicted with 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 InAs , until culminating in immobile reaction p roducts. 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 the properties of intrinsic defects in bulk InAs as colla ted in SAND 2013 - 2477 : Simple intrinsic defects in InAs : Numerical predictions to include Si - containing simple defects likely to be present in a radiation - induced defect reaction sequence . This page intentionally left blank

  19. GaN/Fe core/shell nanowires for nonvolatile spintronics on Si

    SciTech Connect (OSTI)

    Gao Cunxu; Farshchi, Rouin; Roder, Claudia; Dogan, Pinar; Brandt, Oliver

    2011-06-15

    We explore the relationship between the structural and magnetic properties of GaN/Fe core/shell nanowires grown epitaxially on Si substrates. The magnetic properties are consistent with the coexistence of two magnetic contributions: a ferromagnetic response from the single-crystalline Fe particles formed at the nanowire tips, and a superparamagnetic response originating from the granular Fe clusters grown on the nanowire sidewalls, giving them a corncob-like morphology. We show that our interpretation of the origin of the magnetic behavior can be confirmed by the viscous decay of magnetic remanence in the nanowires. Ferromagnetic remanence is observed both parallel and perpendicular to the nanowire axis, making such structures appealing as high-density nonvolatile spintronic components on Si.

  20. Molecular dynamics simulations of 30 and 2 keV Ga in Si

    SciTech Connect (OSTI)

    Giannuzzi, Lucille A.; Garrison, Barbara J.

    2007-09-15

    Focused Ga{sup +} ion beams are routinely used at high incident angles for specimen preparation. Molecular dynamics simulations of 2 and 30 keV Ga bombardment of Si(011) at a grazing angle of 88 deg. were conducted to assess sputtering characteristics and damage depth. The bombardment of atomically flat surfaces and surfaces with vacancies shows little energy transfer yielding ion reflection. The bombardment of surfaces with adatoms allows for the coupling of the energy of motion parallel to the surface into the substrate resulting in sputtering. The adatom and one other Si atom eject, and motion in the substrate occurs down to a depth of 13 A. Experimental evidence shows that sputtering is a reality, suggesting that an atomically flat surface is never achieved.

  1. The effect of microscopic texture on the direct plasma surface passivation of Si solar cells

    SciTech Connect (OSTI)

    Mehrabian, S.; Xu, S.; Qaemi, A. A.; Shokri, B.; Chan, C. S.; Ostrikov, K.

    2013-04-15

    Textured silicon surfaces are widely used in manufacturing of solar cells due to increasing the light absorption probability and also the antireflection properties. However, these Si surfaces have a high density of surface defects that need to be passivated. In this study, the effect of the microscopic surface texture on the plasma surface passivation of solar cells is investigated. The movement of 10{sup 5} H{sup +} ions in the texture-modified plasma sheath is studied by Monte Carlo numerical simulation. The hydrogen ions are driven by the combined electric field of the plasma sheath and the textured surface. The ion dynamics is simulated, and the relative ion distribution over the textured substrate is presented. This distribution can be used to interpret the quality of the Si dangling bonds saturation and consequently, the direct plasma surface passivation.

  2. Growth and stability of oxidation resistant Si nanocrystals formed by decomposition of alkyl silanes

    SciTech Connect (OSTI)

    Zaitseva, N; Hamel, S; Dai, Z R; Saw, C; Williamson, A J; Galli, G

    2007-01-12

    The synthesis and characterization of 1-10 nm Si nanocrystals highly resistant to oxidation is described. The nanocrystals were prepared by thermal decomposition of tetramethylsilane at 680 C, or in a gold- induced catalytic process at lower temperatures down to 400-450 C using trioctylamine as an initial solvent. Transmission electron microscopic analysis of samples obtained in the presence of gold show that the nanocrystals form via solid-phase epitaxial attachment of Si to the gold crystal lattice. The results of computational modeling performed using first principles density functional theory (DFT) calculations predict that the enhanced stability of nanocrystals to oxidation is due to the presence of N or N-containing groups on the surface of nanocrystals.

  3. Fabrication of a single layer graphene by copper intercalation on a SiC(0001) surface

    SciTech Connect (OSTI)

    Yagyu, Kazuma; Tochihara, Hiroshi; Tomokage, Hajime; Suzuki, Takayuki; Tajiri, Takayuki; Kohno, Atsushi; Takahashi, Kazutoshi

    2014-02-03

    Cu atoms deposited on a zero layer graphene grown on a SiC(0001) substrate, intercalate between the zero layer graphene and the SiC substrate after the thermal annealing above 600?C, forming a Cu-intercalated single layer graphene. On the Cu-intercalated single layer graphene, a graphene lattice with superstructure due to moir pattern is observed by scanning tunneling microscopy, and specific linear dispersion at the K{sup } point as well as a characteristic peak in a C{sub 1s} core level spectrum, which is originated from a free-standing graphene, is confirmed by photoemission spectroscopy. The Cu-intercalated single layer graphene is found to be n-doped.

  4. Radiation tolerance of the FOXFET biasing scheme for AC-coupled Si microstrip detectors

    SciTech Connect (OSTI)

    Bacchetta, N.; Gotra, Yu. ); Bisello, D.; Da Ros, R.; Giraldo, A. Univ. di Padova . Dipt. di Fisica); Canali, C. Univ. di Modena . Facolta di Ingegneria); Fuochi, P.G. ); Fusaro, G. . Dept. di Elettronica e Informatica); Paccagnella, A. Univ. di Cagliari . Instituto di Elettrotecnica); Verzellesi, G. Univ. di Padova . Dept. di Elettronica e Informatica)

    1993-12-01

    The radiation response of FOXFETs has been studied for proton, gamma and neutron exposures. The punch-through behavior, which represents the normal FET operating conditions in Si microstrip detectors, has been found to be much less sensitive to radiation damage than threshold voltage. The device performance has been elucidated by means of two-dimensional simulations. The main radiation effects have been also taken into account in the numerical analysis and separately examined.

  5. Electrical and photovoltaic characteristics of MoS{sub 2}/Si p-n junctions

    SciTech Connect (OSTI)

    Hao, Lanzhong Liu, Yunjie Gao, Wei; Han, Zhide; Xue, Qingzhong; Zeng, Huizhong; Wu, Zhipeng; Zhu, Jun; Zhang, Wanli

    2015-03-21

    Bulk-like molybdenum disulfide (MoS{sub 2}) thin films were deposited on the surface of p-type Si substrates using dc magnetron sputtering technique and MoS{sub 2}/Si p-n junctions were formed. The vibrating modes of E{sup 1}{sub 2g} and A{sub 1g} were observed from the Raman spectrum of the MoS{sub 2} films. The current density versus voltage (J-V) characteristics of the junction were investigated. A typical J-V rectifying effect with a turn-on voltage of 0.2?V was shown. In different voltage range, the electrical transporting of the junction was dominated by diffusion current and recombination current, respectively. Under the light illumination of 15?mW?cm{sup ?2}, the p-n junction exhibited obvious photovoltaic characteristics with a short-circuit current density of 3.2?mA?cm{sup ?2} and open-circuit voltage of 0.14?V. The fill factor and energy conversion efficiency were 42.4% and 1.3%, respectively. According to the determination of the Fermi-energy level (?4.65?eV) and energy-band gap (?1.45?eV) of the MoS{sub 2} films by capacitance-voltage curve and ultraviolet-visible transmission spectra, the mechanisms of the electrical and photovoltaic characteristics were discussed in terms of the energy-band structure of the MoS{sub 2}/Si p-n junctions. The results hold the promise for the integration of MoS{sub 2} thin films with commercially available Si-based electronics in high-efficient photovoltaic devices.

  6. High Performance Silicon Monoxide (SiO) Electrode for Next Generation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Lithium Ion Batteries - Energy Innovation Portal High Performance Silicon Monoxide (SiO) Electrode for Next Generation Lithium Ion Batteries Lawrence Berkeley National Laboratory Contact LBL About This Technology Publications: PDF Document Publication Park, S.-J., Zhao, H., Ai, G., Wang, C., Song, X., Yuca, N., Battaglia, V. S., Yang, W., Liu, G. "Side Chain Conducting and Phase Separated Polymeric Binders for High Performance Silicon Anodes in Lithium Ion Batteries," Journal of

  7. Controlled synthesis and decoupling of monolayer graphene on SiC(0001)

    SciTech Connect (OSTI)

    Oida, S.; Hannon, J. B.; Tromp, R. M. [IBM Research Division, T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

    2014-04-21

    We describe a process for the growth of a single, electronically decoupled graphene layer on SiC(0001). The method involves annealing in disilane to (1) prepare flat, clean substrates, (2) grow a single graphene layer, and (3) electronically decouple the graphene from the substrate. This approach uses a single process gas, at ?Torr pressures, with modest substrate temperatures, thus affecting a drastic simplification over other processes described in the literature.

  8. Using SiO Anodes for High Capacity, High Rate Electrodes for Lithium Ion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Batteries - Energy Innovation Portal Using SiO Anodes for High Capacity, High Rate Electrodes for Lithium Ion Batteries Lawrence Berkeley National Laboratory Contact LBL About This Technology Technology Marketing Summary Berkeley Lab developed an elegant and inexpensive fabrication method for high performance electrodes with unmatched specific / areal capacities and good capacity retention for application in lithium ion batteries. Description A team of Berkeley Lab researchers led by Gao Liu

  9. Novel Processing of mo-si-b Intermetallics for improved efficiency of power systems

    SciTech Connect (OSTI)

    M.J. Kramer; O. Degirmen; A.J. Thom; M. Akinc

    2004-09-30

    Multiphase composite alloys based on the Mo-Si-B system are candidate materials for ultra-high temperature applications. In non load-bearing applications such as thermal barrier coatings or heat exchangers in fossil fuel burners, these materials may be ideally suited. Alloys based on the Mo{sub 5}Si{sub 3}B{sub x} phase (Tl phase) possess excellent oxidation resistance to at least 1600 C in synthetic air atmospheres. However, the ability of Tl-based alloys to resist aggressive combustion environments has not yet been determined. The present work seeks to investigate the resistance of these Mo-Si-B alloys to simulated combustion atmospheres. Material was pre-alloyed by combustion synthesis, and samples for testing were prepared by classic powder metallurgical processing techniques. Precursor material synthesized by self-heating-synthesis was sintered to densities exceeding 98% in an argon atmosphere at 1800 C. The approximate phase assemblage of the material was 57% Tl, 29% MoB, 14% MoSi{sub 2} (wt%). The alloy was oxidized from 1000-1100 C in flowing air containing water vapor at 18 Torr. At 1000 C the material achieved a steady state mass loss, and at 1100 C the material undergoes a steady state mass gain. The oxidation rate of these alloys in this temperature regime was accelerated by the presence of water vapor compared to oxidation in dry air. The results of microstructural analysis of the tested alloys will be discussed. Techniques and preliminary results for fabricating near-net-shaped parts will also be presented.

  10. Reducing c-Si Module Operating Temperature via PV Packaging Components |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PDF icon pvmrw13_ps5_honeywell_bratcher.pdf More Documents & Publications Agenda for the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado PID Failure of c-Si and Thin-Film Modules and Possible Correlation with Leakage Currents Retrospective Benefit-Cost Evaluation of DOE Investment in Photovoltaic Energy Systems

  11. MEMORANDUM FOR HUMAN RESOURCE DIRECTORS FROM: S~~'I~ OFFICE OF

    Office of Environmental Management (EM)

    December 16, 2010 MEMORANDUM FOR HUMAN RESOURCE DIRECTORS FROM: S~~'I~ OFFICE OF ~MAN CAPITAL MANAGEMENT SUBJECT: POLICY GUIDANCE MEMORANDUM #15 PROCESSING PERSONNEL ACTIONS FOR DETAILS Update 53 to The Guide to Processing Personnel Actions issued by the Office of Personnel Management (OPM), effective September 12, 2010, requires agencies to offiCially document detail actions. As a result, all Servicing Human Resources Offices (SHROs) are now required to document, process, and file certain

  12. Effects of inter-nanocrystal distance on luminescence quantum yield in ensembles of Si nanocrystals

    SciTech Connect (OSTI)

    Valenta, J. Greben, M.; Gutsch, S.; Hiller, D.; Zacharias, M.

    2014-12-15

    The absolute photoluminescence (PL) quantum yield (QY) of multilayers of Silicon nanocrystals (SiNCs) separated by SiO{sub 2} barriers were thoroughly studied as function of the barrier thickness, excitation wavelength, and temperature. By mastering the plasma-enhanced chemical vapor deposition growth, we produce a series of samples with the same size-distribution of SiNCs but variable interlayer barrier distance. These samples enable us to clearly demonstrate that the increase of barrier thickness from ∼1 to larger than 2 nm induces doubling of the PL QY value, which corresponds to the change of number of close neighbors in the hcp structure. The temperature dependence of PL QY suggests that the PL QY changes are due to a thermally activated transport of excitation into non-radiative centers in dark NCs or in the matrix. We estimate that dark NCs represent about 68% of the ensemble of NCs. The PL QY excitation spectra show no significant changes upon changing the barrier thickness and no clear carrier multiplication effects. The dominant effect is the gradual decrease of the PL QY with increasing excitation photon energy.

  13. A direct measurement of the electronic structure of Si nanocrystals and its effect on optoelectronic properties

    SciTech Connect (OSTI)

    Mustafeez, Waqas; Salleo, Alberto; Majumdar, Arka; Vučković, Jelena

    2014-03-14

    Since reports that silicon nanocrystals (Si-NCs) can exhibit direct transition emission, the silicon laser field is at a juncture where the importance of this discovery needs to be evaluated. Most theoretical models predicted a monotonic increase in the bandgap and experimental information currently available on the electronic structure at the Γ valley of these promising materials is circumstantial as it is obtained from emission measurements where competing non-radiative relaxation and recombination processes only provide an incomplete picture of the electronic structure of Si-NCs. Optical absorption, the most immediate probe of the electronic structure beyond the band-edges, showing the evolution of the Γ valley states with nanocrystal size has not been measured. Here, we show such measurements, performed with high dynamic range, allowing us to observe directly the effect of crystal size on the Γ valley splitting far above the band-edges. We show that the splitting is 100 s of meV more pronounced than predicted by pseudo potential calculations and Luttinger-Kohn model. We also show that ultrafast red-shifting emission can be observed in plasma enhanced chemical vapor deposition prepared Si-NCs.

  14. Chemistry of Tantalum Clusters in Solution And on SiO(2) Supports: Analogies And Contrasts

    SciTech Connect (OSTI)

    Nemana, S.; Okamoto, N.L.; Browning, N.D.; Gates, B.C.

    2009-06-03

    Tantalum clusters have been synthesized from Ta(CH{sub 2}Ph){sub 5} on the surface of porous fumed SiO{sub 2}. When these clusters are small, incorporating, on average, several Ta atoms, their chemistry is similar to that of molecular tantalum clusters (and other early transition-metal) clusters. For example, The Ta-Ta bonds in these small supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS), IR, and UV-vis spectroscopy, being similar to those in molecular analogues. The redox reactions of the supported clusters, characterized by X-ray absorption near-edge structure, are analogous to those of early transition-metal clusters in solution. In contrast to the largest of these clusters in solution and in the solid state, those supported on SiO{sub 2} are raftlike, facilitating the substantial metal-support-oxygen bonding that is evident in the EXAFS spectra. Samples consisting of tantalum clusters on SiO{sub 2} catalyze alkane disproportionation and the conversion of methane with n-butane to give other alkanes, but catalytic properties of analogous clusters in solution have barely been explored.

  15. Detailed Chemical Kinetic Modeling of Iso-octane SI-HCCI Transition

    SciTech Connect (OSTI)

    Havstad, Mark A; Aceves, Salvador M; McNenly, Matthew J; Piggott, William T; Edwards, Kevin Dean; Wagner, Robert M; Daw, C Stuart; FINNEY, Charles E A

    2010-01-01

    We describe a CHEMKIN-based multi-zone model that simulates the expected combustion variations in a single-cylinder engine fueled with iso-octane as the engine transitions from spark-ignited (SI) combustion to homogenous charge compression ignition (HCCI) combustion. The model includes a 63-species reaction mechanism and mass and energy balances for the cylinder and the exhaust flow. For this study we assumed that the SI-to-HCCI transition is implemented by means of increasing the internal exhaust gas recirculation (EGR) at constant engine speed. This transition scenario is consistent with that implemented in previously reported experimental measurements on an experimental engine equipped with variable valve actuation. We find that the model captures many of the important experimental trends, including stable SI combustion at low EGR (-0.10), a transition to highly unstable combustion at intermediate EGR, and finally stable HCCI combustion at very high EGR (-0.75). Remaining differences between the predicted and experimental instability patterns indicate that there is further room for model improvement.

  16. Excellent c-Si surface passivation by low-temperature atomic layer deposited titanium oxide

    SciTech Connect (OSTI)

    Liao, Baochen; Hoex, Bram; Aberle, Armin G.; Bhatia, Charanjit S.; Chi, Dongzhi

    2014-06-23

    In this work, we demonstrate that thermal atomic layer deposited (ALD) titanium oxide (TiO{sub x}) films are able to provide a—up to now unprecedented—level of surface passivation on undiffused low-resistivity crystalline silicon (c-Si). The surface passivation provided by the ALD TiO{sub x} films is activated by a post-deposition anneal and subsequent light soaking treatment. Ultralow effective surface recombination velocities down to 2.8 cm/s and 8.3 cm/s, respectively, are achieved on n-type and p-type float-zone c-Si wafers. Detailed analysis confirms that the TiO{sub x} films are nearly stoichiometric, have no significant level of contaminants, and are of amorphous nature. The passivation is found to be stable after storage in the dark for eight months. These results demonstrate that TiO{sub x} films are also capable of providing excellent passivation of undiffused c-Si surfaces on a comparable level to thermal silicon oxide, silicon nitride, and aluminum oxide. In addition, it is well known that TiO{sub x} has an optimal refractive index of 2.4 in the visible range for glass encapsulated solar cells, as well as a low extinction coefficient. Thus, the results presented in this work could facilitate the re-emergence of TiO{sub x} in the field of high-efficiency silicon wafer solar cells.

  17. Disease mapping based on stochastic SIR-SI model for Dengue and Chikungunya in Malaysia

    SciTech Connect (OSTI)

    Samat, N. A.; Ma'arof, S. H. Mohd Imam

    2014-12-04

    This paper describes and demonstrates a method for relative risk estimation which is based on the stochastic SIR-SI vector-borne infectious disease transmission model specifically for Dengue and Chikungunya diseases in Malaysia. Firstly, the common compartmental model for vector-borne infectious disease transmission called the SIR-SI model (susceptible-infective-recovered for human populations; susceptible-infective for vector populations) is presented. This is followed by the explanations on the stochastic SIR-SI model which involve the Bayesian description. This stochastic model then is used in the relative risk formulation in order to obtain the posterior relative risk estimation. Then, this relative estimation model is demonstrated using Dengue and Chikungunya data of Malaysia. The viruses of these diseases are transmitted by the same type of female vector mosquito named Aedes Aegypti and Aedes Albopictus. Finally, the findings of the analysis of relative risk estimation for both Dengue and Chikungunya diseases are presented, compared and displayed in graphs and maps. The distribution from risk maps show the high and low risk area of Dengue and Chikungunya diseases occurrence. This map can be used as a tool for the prevention and control strategies for both diseases.

  18. Effect of graphene on photoluminescence properties of graphene/GeSi quantum dot hybrid structures

    SciTech Connect (OSTI)

    Chen, Y. L.; Ma, Y. J.; Wang, W. Q.; Ding, K.; Wu, Q.; Fan, Y. L.; Yang, X. J.; Zhong, Z. Y.; Jiang, Z. M., E-mail: zmjiang@fudan.edu.cn [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, Shanghai 200433 (China); Chen, D. D.; Xu, F. [SHU-SolarE R and D Lab, Department of Physics, College of Science, Shanghai University, Shanghai 200444 (China)

    2014-07-14

    Graphene has been discovered to have two effects on the photoluminescence (PL) properties of graphene/GeSi quantum dot (QD) hybrid structures, which were formed by covering monolayer graphene sheet on the multilayer ordered GeSi QDs sample surfaces. At the excitation of 488?nm laser line, the hybrid structure had a reduced PL intensity, while at the excitation of 325?nm, it had an enhanced PL intensity. The attenuation in PL intensity can be attributed to the transferring of electrons from the conducting band of GeSi QDs to the graphene sheet. The electron transfer mechanism was confirmed by the time resolved PL measurements. For the PL enhancement, a mechanism called surface-plasmon-polariton (SPP) enhanced absorption mechanism is proposed, in which the excitation of SPP in the graphene is suggested. Due to the resonant excitation of SPP by incident light, the absorption of incident light is much enhanced at the surface region, thus leading to more exciton generation and a PL enhancement in the region. The results may be helpful to provide us a way to improve optical properties of low dimensional surface structures.

  19. Characterization of V-shaped defects in 4H-SiC homoepitaxial layers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Lihua; Su, Dong; Kisslinger, Kim; Stach, Eric; Chung, Gil; Zhang, Jie; Thomas, Bernd; Sanchez, Edward K; Mueller, Stephan G.; Hansen, Darren; et al

    2014-12-04

    Synchrotron white beam x-ray topography images show that faint needle-like surface morphological features observed on the Si-face of 4H-SiC homoepitaxial layers using Nomarski optical microscopy are associated with V shaped stacking faults in the epilayer. KOH etching of the V shaped defect reveals small oval pits connected by a shallow line which corresponding to the surface intersections of two partial dislocations and the stacking fault connecting them. Transmission electron microscopy (TEM) specimens from regions containing the V shaped defects were prepared using focused ion beam milling, and stacking sequences of (85), (50) and (63) are observed at the faulted regionmore » with high resolution TEM. In order to study the formation mechanism of V shaped defect, low dislocation density 4H-SiC substrates were chosen for epitaxial growth, and the corresponding regions before and after epitaxy growth are compared in SWBXT images. It is found that no defects in the substrate are directly associated with the formation of the V shaped defect. Simulation results of the contrast from the two partial dislocations associated with V shaped defect in synchrotron monochromatic beam x-ray topography reveals the opposite sign nature of their Burgers vectors. Therefore, a mechanism of 2D nucleation during epitaxy growth is postulated for the formation of the V shaped defect, which requires elimination of non-sequential 1/4[0001] bilayers from the original structure to create the observed faulted stacking sequence.« less

  20. C60 -induced Devil's Staircase transformation on a Pb/Si(111) wetting layer

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Lin -Lin; Johnson, Duane D.; Tringides, Michael C.

    2015-12-03

    Density functional theory is used to study structural energetics of Pb vacancy cluster formation on C60/Pb/Si(111) to explain the unusually fast and error-free transformations between the “Devil's Staircase” (DS) phases on the Pb/Si(111) wetting layer at low temperature (~110K). The formation energies of vacancy clusters are calculated in C60/Pb/Si(111) as Pb atoms are progressively ejected from the initial dense Pb wetting layer. Vacancy clusters larger than five Pb atoms are found to be stable with seven being the most stable, while vacancy clusters smaller than five are highly unstable, which agrees well with the observed ejection rate of ~5 Pbmore » atoms per C60. Furthermore, the high energy cost (~0.8 eV) for the small vacancy clusters to form indicates convincingly that the unusually fast transformation observed experimentally between the DS phases, upon C60 adsorption at low temperature, cannot be the result of single-atom random walk diffusion but of correlated multi-atom processes.« less

  1. Valence electronenergy-lossspectroscopystudyofZrSiO4 and ZrO2

    SciTech Connect (OSTI)

    Spence, John; Jiang, Nan

    2013-07-01

    ZrSiO4 (zircon) and m-ZrO2 (zirconia) are fundamental and industrially important materials.This work reports the detailed valence electron energy-loss spectroscopy (VEELS) studies of these compounds. The dielectric response functions, as well as single-electron interband transition spectra,are derived from VEELS data for both ZrSiO4 and m-ZrO2, in the rang e550 eV using the KramersKronig analysis method. Our interpretation of the interband transitions is given with the aid of ab initio calculations of density of states. The bandgap energies for both materials are also measured using VEELS.The surface and bulk plasmons are identified: the surface plasmon peaks locate at around 12 eV,and two bulk plasmon peaks are ~1516 eV and ~2527 eV,respectively.Although similarities in the VEELS exist between ZrSiO4 and m-ZrO2, two majo rdifferences are als onoticed and explained in terms of composition and structure differences.

  2. Characterization of V-shaped defects in 4H-SiC homoepitaxial layers

    SciTech Connect (OSTI)

    Zhang, Lihua; Su, Dong; Kisslinger, Kim; Stach, Eric; Chung, Gil; Zhang, Jie; Thomas, Bernd; Sanchez, Edward K; Mueller, Stephan G.; Hansen, Darren; Loboda, Mark J.; Wu, Fangzhen; Wang, Huanhuan; Raghothamachar, Balaji; Dudley, Michael

    2014-12-04

    Synchrotron white beam x-ray topography images show that faint needle-like surface morphological features observed on the Si-face of 4H-SiC homoepitaxial layers using Nomarski optical microscopy are associated with V shaped stacking faults in the epilayer. KOH etching of the V shaped defect reveals small oval pits connected by a shallow line which corresponding to the surface intersections of two partial dislocations and the stacking fault connecting them. Transmission electron microscopy (TEM) specimens from regions containing the V shaped defects were prepared using focused ion beam milling, and stacking sequences of (85), (50) and (63) are observed at the faulted region with high resolution TEM. In order to study the formation mechanism of V shaped defect, low dislocation density 4H-SiC substrates were chosen for epitaxial growth, and the corresponding regions before and after epitaxy growth are compared in SWBXT images. It is found that no defects in the substrate are directly associated with the formation of the V shaped defect. Simulation results of the contrast from the two partial dislocations associated with V shaped defect in synchrotron monochromatic beam x-ray topography reveals the opposite sign nature of their Burgers vectors. Therefore, a mechanism of 2D nucleation during epitaxy growth is postulated for the formation of the V shaped defect, which requires elimination of non-sequential 1/4[0001] bilayers from the original structure to create the observed faulted stacking sequence.

  3. Enhanced Ge/Si(001) island areal density and self-organization due to P predeposition

    SciTech Connect (OSTI)

    Cho, B.; Bareno, J.; Petrov, I.; Greene, J. E.

    2011-05-01

    The predeposition of P, with coverages {theta}{sub P} ranging from 0 to 1 ML, on Si(001) significantly increases both the areal density and spatial self-organization of Ge islands grown by gas-source molecular beam epitaxy from hydride precursors. The Ge island density {rho}{sub Ge} initially increases with {theta}{sub P}, reaching a maximum of 1.4 x 10{sup 10} cm{sup -2} at {theta}{sub P} = 0.7 ML, a factor of four times higher than on bare Si(001) under the same deposition conditions, before decreasing at higher P coverages. The increase in {rho}{sub Ge}({theta}{sub P}) is due to a corresponding decrease in Ge adatom mean free paths resulting from passivation of surface dangling bonds by adsorbed pentavalent P atoms which, in addition, leads to surface roughening and, therefore, higher Ge coverages at constant Ge{sub 2}H{sub 6} dose. As {theta}{sub P} (and hence, {rho}{sub Ge}) increases, so does the degree of Ge island ordering along <100> directions due to the anisotropic strain field surrounding individual islands. Similar results are obtained for Ge island growth on P-doped Si(001) layers where strong P surface segregation provides partial monolayer coverage prior to Ge deposition.

  4. Reversible Electrochemical Insertion of Lithium into Type I Ba8AlySi46-y Clathrate

    SciTech Connect (OSTI)

    Li, Ying; Raghavan, Rahul; Wagner, Nicholas; Davidowski, Stephen; Baggetto, Loic; Zhao, Ran; Cheng, Qian; Holland, Gregory p; Yarger, Jeffery L; Veith, Gabriel M; Ellis-Terrell, Carol; Miller, Michael A; Chan, Kwai; Chan, Candace

    2015-01-01

    Silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on Ba8AlySi46-y for the anode material in lithium-ion batteries. Post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from larger volume changes. The lithiation/delithiation processes are proposed to occur in single phase reactions at approximately 0.2 and 0.4 V vs. Li/Li+, respectively, distinct from other diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g-1 at a 5 mA g-1 rate were observed for silicon clathrate with composition Ba8Al8.54Si37.46, corresponding to Li:Si of 1.18:1. The results show that silicon clathrates could be promising durable anodes for lithium-ion batteries.

  5. Magnetic domain structure and domain-wall energy in UFe{sub 8}Ni{sub 2}Si{sub 2} and UFe{sub 6}Ni{sub 4}Si{sub 2} intermetallic compounds

    SciTech Connect (OSTI)

    Wyslocki, J.J.; Suski, W.; Wochowski, K.

    1994-03-01

    Magnetic domain structures in the UFe{sub 8}Ni{sub 2}Si{sub 2} and UFe{sub 6}Ni{sub 4}Si{sub 2} compounds were studied using the powder pattern method. The domain structure observed is typical for uniaxial materials. The domain-wall energy density {gamma} was determined from the average surface domain width D{sub s} observed on surfaces perpendicular to the easy axis as equal to 16 erg/cm{sup 2} for UFe{sub 8}Ni{sub 2}Si{sub 2} and 10 erg/cm{sup 2} for UFe{sub 6}Ni{sub 4}Si{sub 2}. Moreover, the critical diameter for single domain particle D{sub c} was calculated for the studied compounds.

  6. Distribution of Pd, Ag & U in the SiC Layer of an Irradiated TRISO Fuel Particle

    SciTech Connect (OSTI)

    Thomas M. Lillo; Isabella J. van Rooyen

    2014-08-01

    The distribution of silver, uranium and palladium in the silicon carbide (SiC) layer of an irradiated TRISO fuel particle was studied using samples extracted from the SiC layer using focused ion beam (FIB) techniques. Transmission electron microscopy in conjunction with energy dispersive x-ray spectroscopy was used to identify the presence of the specific elements of interest at grain boundaries, triple junctions and precipitates in the interior of SiC grains. Details on sample fabrication, errors associated with measurements of elemental migration distances and the distances migrated by silver, palladium and uranium in the SiC layer of an irradiated TRISO particle from the AGR-1 program are reported.

  7. Multi-mode interference revealed by two photon absorption in silicon rich SiO{sub 2} waveguides

    SciTech Connect (OSTI)

    Manna, S. E-mail: mattia.mancinelli@unitn.it; Ramiro-Manzano, F.; Mancinelli, M. E-mail: mattia.mancinelli@unitn.it; Turri, F.; Pavesi, L.; Ghulinyan, M.; Pucker, G.

    2015-02-16

    Photoluminescence (PL) from Si nanocrystals (NCs) excited by two-photon absorption (TPA) has been observed in Si nanocrystal-based waveguides fabricated by plasma enhanced chemical vapor deposition. The TPA excited photoluminescence emission resembles the one-photon excited photoluminescence arising from inter-band transitions in the quantum confined Si nanocrystals. By measuring the non-linear transmission of waveguides, a large TPA coefficient of β up to 10{sup −8 }cm/W has been measured at 1550 nm. These values of β depend on the Si NCs size and are two orders of magnitude larger than the bulk silicon value. Here, we propose to use the TPA excited visible PL emission as a tool to map the spatial intensity profile of the 1550 nm propagating optical modes in multimode waveguides. In this way, multimode interference has been revealed experimentally and confirmed through a finite element simulation.

  8. Vehicle Technologies Office Merit Review 2015: Low-cost, High Energy Si/Graphene Anodes for Li-ion Batteries

    Broader source: Energy.gov [DOE]

    Presentation given by XG Sciences at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about low-cost, high energy Si/graphene...

  9. Electrical properties of diluted n- and p-Si{sub 1?x}Ge{sub x} at small x

    SciTech Connect (OSTI)

    Emtsev, V. V., E-mail: emtsev@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Abrosimov, N. V. [Leibniz Institute for Crystal Growth (Germany); Kozlovskii, V. V. [St. Petersburg Polytechnical State University (Russian Federation); Oganesyan, G. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

    2014-12-15

    Hall effect and conductivity measurements are taken on Si{sub 1?x}Ge{sub x} of n- and p-type at x ? 0.05. Much attention is given to electrical measurements over a temperature interval of 25 to 40 K where the mobility of charged carriers is strongly affected by alloy scattering. The partial mobility of electrons and holes due to this scattering mechanism is estimated for n-Si{sub 1?x}Ge{sub x} and p-Si{sub 1?x}Ge{sub x} at small x. Together with this, an effect of the presence of Ge atoms upon the ionization energy of phosphorus and boron impurities is investigated. Some points related to an inhomogeneous distribution of Ge atoms in Si{sub 1?x}Ge{sub x} are discussed.

  10. Highly dispersed SiOx/Al2O3 catalysts illuminate the reactivity of isolated silanol sites

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mouat, Aidan R.; George, Cassandra; Kobayashi, Takeshi; Pruski, Marek; van Duyne, Richard P.; Marks, Tobin J.; Stair, Peter C.

    2015-09-23

    The reaction of γ-alumina with tetraethylorthosilicate (TEOS) vapor at low temperatures selectively yields monomeric SiOx species on the alumina surface. These isolated (-AlO)3Si(OH) sites are characterized by PXRD, XPS, DRIFTS of adsorbed NH3, CO, and pyridine, and 29Si and 27Al DNP-enhanced solid-state NMR spectroscopy. The formation of isolated sites suggests that TEOS reacts preferentially at strong Lewis acid sites on the γ-Al2O3 surface, functionalizing the surface with “mild” Brønsted acid sites. As a result, for liquid-phase catalytic cyclohexanol dehydration, these SiOx sites exhibit up to 3.5-fold higher specific activity than the parent alumina with identical selectivity.

  11. Tunable photoluminescence of self-assembled GeSi quantum dots by B{sup +} implantation and rapid thermal annealing

    SciTech Connect (OSTI)

    Chen, Yulu; Wu, Shan; Ma, Yinjie; Fan, Yongliang; Yang, Xinju; Zhong, Zhenyang; Jiang, Zuimin

    2014-06-21

    The layered GeSi quantum dots (QDs) are grown on (001) Si substrate by molecular beam epitaxy. The photoluminescence (PL) peak of the as-grown GeSi quantum dots has obvious blue shift and enhancement after processed by ion implantation and rapid thermal annealing. It is indicated that the blue shift is originated from the interdiffusion of Ge and Si at the interface between QDs and the surrounding matrix. The dependence of PL intensity on the excitation power shows that there are the nonradiative centers of shallow local energy levels from the point defects caused by the ion implantation, but not removed by the rapid thermal annealing. The tunable blue shift of the PL position from the 1300?nm to 1500?nm region may have significant application value in the optical communication.

  12. Effect of annealing temperature on the contact properties of Ni/V/4H-SiC structure

    SciTech Connect (OSTI)

    Dai, Chong-Chong; Zhou, Tian-Yu; University of Chinese Academy of Sciences, Beijing 100049 ; Liu, Xue-Chao Zhuo, Shi-Yi; Kong, Hai-Kuan; Yang, Jian-Hua; Shi, Er-Wei

    2014-04-15

    A sandwich structure of Ni/V/4H-SiC was prepared and annealed at different temperatures from 650?C to 1050?C. The electrical properties and microstructures were characterized by transmission line method, X-ray diffraction, Raman spectroscopy and transmission electron microscopy. A low specific contact resistance of 3.3 10{sup -5} ?cm{sup 2} was obtained when the Ni/V contact was annealed at 1050?C for 2 min. It was found that the silicide changed from Ni{sub 3}Si to Ni{sub 2}Si with increasing annealing temperature, while the vanadium compounds appeared at 950?C and their concentration increased at higher annealing temperature. A schematic diagram was proposed to explain the ohmic contact mechanism of Ni/V/4H-SiC structure.

  13. Low resistance Ti Ohmic contacts to 4H-SiC by reducing barrier heights without high temperature annealing

    SciTech Connect (OSTI)

    Huang Lingqin; Liu Bingbing; Zhu Qiaozhi; Chen Suhua; Gao Mingchao; Wang Dejun; Qin Fuwen

    2012-06-25

    Ti Ohmic contacts to relatively highly doped (1 Multiplication-Sign 10{sup 18} cm{sup -3}) n-type 4H-SiC have been produced, without high temperature annealing, by means of low temperature electronic cyclotron resonance microwave hydrogen plasma pre-treatment (HPT) of the SiC surface. The as-deposited Ti/4H-SiC contacts show Ohmic properties, and the specific contact resistance obtained is as low as 2.07 Multiplication-Sign 10{sup -4}{Omega}{center_dot}cm{sup 2} after annealing at low temperatures (400 Degree-Sign C). This is achieved by low barrier height at Ti/SiC interface, which could be attributed to decrease of surface states density by the HPT releasing Fermi level pinning, and to band-gap narrowing, image-force, and thermionic-field emission at high doping.

  14. Chemical and electronic passivation of 4H-SiC surface by hydrogen-nitrogen mixed plasma

    SciTech Connect (OSTI)

    Liu, Bingbing; Huang, Lingqin; Zhu, Qiaozhi; Wang, Dejun; Qin, Fuwen

    2014-05-19

    We propose a low-temperature electron cyclotron resonance microwave hydrogen-nitrogen mixed plasma treatment method for passivating 4H-SiC surface and investigate the effects of treatment on the structural, chemical, and electronic properties of the surface. The results indicate that the method is highly controllable and could result in an atomically ordered, unreconstructed, smooth, and clean SiC surface. The absence of surface band bending is indicative of an electronically passivated SiC surface with a surface state density as low as 5.47??10{sup 10}?cm{sup ?2}. This effect could be attributed to the simultaneous effects of H and N passivating on SiC surface.

  15. Inhomogeneous broadening and peak shift of the 7.6 eV optical absorption band of oxygen vacancies in SiO{sub 2}

    SciTech Connect (OSTI)

    Kajihara, Koichi, E-mail: kkaji@tmu.ac.jp [Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji 192-0397 (Japan); Skuja, Linards [Institute of Solid State Physics, University of Latvia, Kengaraga iela 8, LV1063 Riga (Latvia); Hosono, Hideo [Materials and Structures Laboratory and Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2014-10-21

    The peak parameters of radiation-induced 7.6 eV optical absorption band of oxygen vacancies (Si-Si bonds) were examined for high-purity synthetic ?-quartz and amorphous SiO{sub 2} (a?SiO{sub 2}) exposed to {sup 60}Co ?-rays. The peak shape is asymmetric with the steeper edge at the lower energy side both in ?-quartz and a?SiO{sub 2}, and the peak energy is larger for ?-quartz than that for a?SiO{sub 2}. The full width at half maximum for a?SiO{sub 2} is larger by ?40-60% than that for ?-quartz, and it increases with an increase in the disorder of the a?SiO{sub 2} network, which is enhanced by raising the temperature of preannealing before irradiation, i.e., fictive temperature. These data are interpreted from the viewpoint of the site-to-site distribution of the Si-Si bond length in a?SiO{sub 2}.

  16. Study of the I-V characteristics of nanostructured Pd films on a Si substrate after vacuum annealing

    SciTech Connect (OSTI)

    Tomilin, S. V., E-mail: tomilin_znu@mail.ru; Yanovsky, A. S.; Tomilina, O. A.; Mikaelyan, G. R. [Zaporozhye National University, Department of Semiconductor Physics (Ukraine)

    2013-06-15

    The I-V characteristics of nanostructured Pd films on a Si substrate are investigated. The nanostructures (nanoislands) are formed by the vacuum annealing of continuous ultrathin Pd films sputtered onto a substrate. The shape of the I-V characteristics of the investigated Si substrate-Pd film system is shown to be heavily dependent on the degree of film nanostructuring. The surface morphology of the films is studied using scanning electron microscopy.

  17. X-rays structural analysis and thermal stability studies of the ternary compound {alpha}-AlFeSi

    SciTech Connect (OSTI)

    Roger, J.; Bosselet, F.; Viala, J.C.

    2011-05-15

    From literature data presently available, the decomposition temperature and the nature of the decomposition reaction of the ternary compound {alpha}-AlFeSi (also designated as {alpha}{sub H} or {tau}{sub 5}) are not clearly identified. Moreover, some uncertainties remain concerning its crystal structure. The crystallographic structure and thermochemical behaviour of the ternary compound {alpha}-AlFeSi were meticulously studied. The crystal structure of {alpha}-AlFeSi was examined at room temperature from X-ray single crystal intensity data. It presents hexagonal symmetry, space group P6{sub 3}/mmc with unit cell parameters (293 K) a=12.345(2) A and c=26.210(3) A (V=3459 A{sup 3}). The average chemical formula obtained from refinement is Al{sub 7.1}Fe{sub 2}Si. From isothermal reaction-diffusion experiments and Differential Thermal Analysis, the title compound decomposes peritectically upon heating into {theta}-Fe{sub 4}Al{sub 13}(Si), {gamma}-Al{sub 3}FeSi and a ternary Al-rich liquid. Under atmospheric pressure, the temperature of this reversible transformation has been determined to be 772{+-}12 {sup o}C. -- Graphical abstract: Partial representation of the crystal structure of the {alpha}-Al{sub 7.1}Fe{sub 2}Si compound. Display Omitted Highlights: The main findings of our work are: {yields} a detailed X-rays crystal structure determination of the ternary compound {alpha}-AlFeSi. {yields} The precision of the silicon atoms positions in the crystal structure. {yields} A precised determination of the decomposition temperature of this compound.

  18. Impedance spectroscopy study of SiO2-Li2O:Nd2O3 glasses

    SciTech Connect (OSTI)

    Pereia, R.; Gozzo, C B; Guedes, I.; Boatner, Lynn A; Terezo, A J; Costa, M M

    2014-01-01

    In the present study, neodymium-doped lithium silicate glasses have been prepared by the conventional melt-quenching technique. The dielectric properties, electric modulus and electrical conductivity of SiO2-Li2O (SiLi-0Nd) and SiO2-Li2O:Nd2O3 (SiLi-1.35Nd) have been studied from 1 Hz to 1 MHz in the 333 423 K temperature range. At a given temperature and frequency, we observe that the resistivity increases while the conductivity accordingly decreases when neodymium ions are added to the glass matrix. The activation energy of two distinct regions was evaluated from the ln( dc)=f(1/T) plot and was found to be E1(T<363K)=0.61(0.66)eV and E2(T>363K)=1.26(1.09)eV for SiLi-0Nd (SiLi-1,35Nd). The dielectric constant ( Re) decreases while the dielectric loss (tan ( )) increases under Nd2O3 doping. We also observe that for both glasses, Re and tan ( ) tend to increase with increasing temperature and decrease with increasing frequency.

  19. Angular distribution and recoil effect for 1 MeV Au+ ions through a Si3N4 thin foil

    SciTech Connect (OSTI)

    Jin, Ke; Zhu, Zihua; Manandhar, Sandeep; Liu, Jia; Chen, Chien-Hung; Shutthanandan, Vaithiyalingam; Thevuthasan, Suntharampillai; Weber, William J; Zhang, Yanwen

    2014-01-01

    The Stopping and Range of Ions in Matter (SRIM) code has been widely used to predict nuclear stopping power and angular distribution of ion-solid collisions. However, experimental validation of the predictions is insufficient for slow heavy ions in nonmetallic compounds. In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) is applied to determine the angular distribution of 1 MeV Au ions after penetrating a Si3N4 foil with a thickness of ~100 nm. The exiting Au ions are collected by a Si wafer located ~14 mm behind the Si3N4 foil, and the resulting 2-dimensional distribution of Au ions on the Si wafer is measured by ToF-SIMS. The SRIM-predicted angular distribution of Au ions through the Si3N4 thin foil is compared with the measured results, indicating that SRIM slightly overestimates the nuclear stopping power by up to 10%. In addition, thickness reduction of the suspended Si3N4 foils induced by 1 MeV Au ion irradiation is observed with an average loss rate of ~107 atom/ion.

  20. Preparation and characterization of SiO?:Sm? nanotube arrays with 1.06 ?m laser antireflective property

    SciTech Connect (OSTI)

    Tan, Wei-min; Huang, Ning; Wang, Li-jun; Song, Tian-shun; Lu, Chun-hua; Wang, Liu-fang; Zhang, Jun-zhi

    2013-05-01

    SiO?: Sm? nanotube arrays with excellent antireflective property at 1.06 ?m were synthesized by a template-assisted solgel process. The molecular structure, morphology and optical properties of the fabricated SiO?:Sm? nanotube arrays were investigated by a Fourier transform infrared spectroscope (FTIR), a Scanning electron microscope (SEM), and a spectro-fluorometer, respectively. The experimental results demonstrate that the SiO?:Sm? nanotube arrays were formed via the AAO membrane during the solgel process. The remarkable antireflective characteristic of about 0.166% at 1.06 ?m was attributed to the drastic decrease of effective refraction index which enhances the matching effect between air and substrate. As well as the absorption performance of Sm? at 1.06 ?m which consumes the energies of incident light. - Graphical abstract: Directional aligned SiO?:Sm? nanotube arrays were synthesized in AAO template by solgel process, and the antiflective performance of arrays is prominent comparing to the blank AAO template. Highlights: SiO?:Sm? nanotube arrays are synthesized by a template-assisted solgel process. SiO?:Sm? nanotube arrays have remarkable antireflective properties at 1.06 ?m. The subwavelength structure results in a decrease of effective refraction index. The absorption performance of Sm? at 1.06 ?m consume the energies of incident light.