Sample records for addthis dot harris

  1. Women @ Energy: Dot Harris | Department of Energy

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your DensityEnergy U.S.-China Electric VehicleCenters | Department ofoftoMayWisingJoanne Bard Women @DebraDot

  2. Fossil Energy Acting Assistant Secretary Recognized at Black...

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

    the Year Awards February 19, 2013 - 8:54am Addthis Director Dot Harris presents Chris Smith, Principal Deputy Assistant Secretary and Acting Assistant Secretary of Fossil Energy,...

  3. Women @ Energy: Dot Harris | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742Energy China 2015ofDepartment of EnergyThe U.S.Department ofWomen @Women @AsDr.WomenAsLaDoris

  4. North Carolina Nuclear Profile - Harris

    U.S. Energy Information Administration (EIA) Indexed Site

    Harris" "Unit","Summer capacity (mw)","Net generation (thousand mwh)","Summer capacity factor (percent)","Type","Commercial operation date","License expiration date"...

  5. Mr. Harry S. Cohen

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7 August 2008 Office7-TACi+J-UN 2 0a50b Mr. Harry

  6. Harry S. Truman - Hanford Site

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHallNot Logged3 HanfordHarry S. Truman Hanford

  7. Harris Walker | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742Energy ChinaofSchaefer To:Department of Energy Completing the OfficeHarris Walker -

  8. Harry J. Holzer John M. Quigley

    E-Print Network [OSTI]

    Sekhon, Jasjeet S.

    Harry J. Holzer John M. Quigley Steven Raphael Public Transit and the Spatial Distribution, with particularly large effects for minority workers and individuals on public assistance (O'Regan and Quigley, 1999

  9. Harris County- LEED Requirement for County Buildings

    Broader source: Energy.gov [DOE]

    In 2009, the Harris County Commissioners Court approved a measure that requires all new county buildings to meet minimum LEED certification standards. Buildings do not have to register with the the...

  10. Carbon nanotube composites P. J. F. Harris*

    E-Print Network [OSTI]

    Harris, Peter J F

    Carbon nanotube composites P. J. F. Harris* Carbon nanotubes are molecular-scale tubes of graphitic carbon with outstanding properties. They are among the stiffest and strongest fibres known, with Young. There is currently great interest in exploiting these properties by incorporating carbon nanotubes into some form

  11. anim par harri: Topics by E-print Network

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

    Management and Restoration Websites Summary: Ma, Harris, Gao and Ding QUARTERLY PROGRESS REPORT October 012009 - December312009 Recycling its proper management and recycling...

  12. User:Harris | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to:Ezfeedflag JumpID-fTri Global Energy LLCEnergy) RedirectCwebber JumpUser page Edit withHarris

  13. Harry E Mynick | Princeton Plasma Physics Lab

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cn SunnybankD.jpgHanford LEED&soil HanfordHappyHarold PaulHarry E Mynick

  14. Harry Frank | Photosynthetic Antenna Research Center

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cn SunnybankD.jpgHanford LEED&soil HanfordHappyHarold PaulHarry E

  15. Timeline: A Harry and Johnny Collection

    E-Print Network [OSTI]

    Multiple Contributors

    AD NAUSEUM PRESS 3613 West Park Road . Cleveland, Ohio 44111 " 154 FIRST MORNING By Jean Chabot (June 197 3) That ~t moment at my doo~, ta.6t rU.g ht, You w~e ~omehow lih.e a. ba.by bhr.d., Lo~t, a.6~d not only o6 c~ but o 6 ~ ha.dow.6....d wome.n. Ca.n you cha.nge. ;the. ha.bm o~ a. U6e.ti.me.? How long be.6o1Le. 4ome. l.a.dy come.& along a.nd 4.te.al4 you 61Lom me.? "This is home now," Harry said again, stubbornly. "You're all the home I want. You and your blue eyes and your golden...

  16. Quantum Dots: Theory

    E-Print Network [OSTI]

    Vukmirovic, Nenad

    2010-01-01T23:59:59.000Z

    Petersilka, Density Functional Theory (Springer, New York,Quantum Dots: Theory Nenad Vukmirovi´ and Lin-Wang Wang cdensity functional theory; electronic structure; empirical

  17. Development of an ozone climatology for Harris County, Texas

    SciTech Connect (OSTI)

    Balentine, H.W.; Carter, J.C. (Radian Corp., Austin, TX (USA)); Preston, J. (Tenneco Polymers, Houston, TX (US))

    1987-01-01T23:59:59.000Z

    The Houston Regional Monitoring Corporation (HRM) has performed continuous ambient air quality and meteorological monitoring in the Ship Channel area of east Harris County since August 1981. The HRM monitoring network is one of the largest Environmental Protection Agency (EPA) approved Prevention of Significant Deterioration (PSD) monitoring network in the United States operated by an industrial group. As an adjunct to its monitoring. HRM has funded extensive meteorological and statistical analyses of ozone monitoring data in Harris County. One of the goals of these studies was to determine those meteorological conditions responsible for the formation of elevated ozone concentrations in Harris County. The analyses performed included the use of principal component analysis and cluster analysis. These analysis techniques have individually been applied to ozone and air quality research problems. The combined use of these techniques in this analysis, however, is a unique application of these statistical tools to an ozone air quality analysis. As a result of these analyses, a climatology of those episodes conducive to elevated ozone formation in Harris County was developed.

  18. PREFETCHING RESULTS OF WEB SEARCHES Harry Foxwell Daniel A. Menasc

    E-Print Network [OSTI]

    Menascé, Daniel A.

    services. A user wishes to locate Web sites that match query keywords. A query term or phrase is entered advertising images and text. A search for a common term such as "dinosaur" may return tens of thousandsPREFETCHING RESULTS OF WEB SEARCHES Harry Foxwell Daniel A. Menascé Sun Microsystems Dept

  19. A Taxonomy of Parallel Prefix Networks David Harris

    E-Print Network [OSTI]

    Harris, David Money

    A Taxonomy of Parallel Prefix Networks David Harris Harvey Mudd College / Sun Microsystems of logic levels, fanout, and wiring tracks. This paper presents a three-dimensional taxonomy that not only for wide adders. This paper develops a taxonomy of parallel prefix networks based on stages, fanout

  20. Hierarchical k-Means for Unsupervised Learning Harry Gifford

    E-Print Network [OSTI]

    Treuille, Adrien

    Hierarchical k-Means for Unsupervised Learning Harry Gifford Carnegie Mellon University Abstract In this paper we investigate how to accelerate k-means based unsupervised learning algorithms with hierar- chical k-means. We show that hierarchical k-means significantly speeds up k-means based learning

  1. Director Dot Harris Inspires Girls at DigiGirlz Day Event | Department of

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33Frequently20,000 Russian NuclearandJunetrack graphics4Dimitri Kusnezov - Chief Scientist

  2. Department of Energy's Dot Harris Honored for Blazing Path for Women |

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directed off Energy.gov. Are you0andEnergyGlobal Nuclearof aDepartment oftheAL 2010-5 Rev1Department of

  3. A quantum dot heterojunction photodetector

    E-Print Network [OSTI]

    Arango, Alexi Cosmos, 1975-

    2005-01-01T23:59:59.000Z

    This thesis presents a new device architecture for photodetectors utilizing colloidally grown quantum dots as the principle photo-active component. We implement a thin film of cadmium selenide (CdSe) quantum dot sensitizers, ...

  4. Modeling Harry's Brook Watershed Alexandra Konings, REU 2006 Tracing the Water

    E-Print Network [OSTI]

    Petta, Jason

    for Undergraduates, 2006 #12;Modeling Harry's Brook Watershed Alexandra Konings, REU 2006 Urban Hydrology Water's Storm Water Management Model (SWMM) Solves differential and algebraic equations involved in calculatingModeling Harry's Brook Watershed Alexandra Konings, REU 2006 Tracing the Water: Detailed Modeling

  5. Harris County, Texas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, search OpenEI ReferenceJumpEnergyStrategy | OpenHalfWind JumpHarfordHarris

  6. DOT WEB PAGES (plain text) 1 DOT WWW Pages --Plain Text Copy June 15, 2014

    E-Print Network [OSTI]

    Rutten, Rob

    ://www.staff.science.uu.nl/ rutte101/dot Plain version: no images, photographs or figures Contents 1 DOT news 1 2 DOT at a glance 2. The DOT website is now at http://www.staff.science.uu.nl/~rutte101/dot. The DOT database is now at ftp

  7. Nontoxic quantum dot research improves solar cells

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

    Nontoxic quantum dot research improves solar cells Nontoxic quantum dot research improves solar cells Solar cells made with low-cost, nontoxic copper-based quantum dots can achieve...

  8. Harris County- Green Building Tax Abatement for New Commercial Construction (Texas)

    Broader source: Energy.gov [DOE]

    In 2008, the Harris County Commissioners Court adopted guidelines for partial tax abatements for new construction of commercial LEED-certified buildings. The tax abatement was renewed in 2009, and...

  9. Department of XXXX Engineering Fall 2011 Harris2-Harnessing Human Energy

    E-Print Network [OSTI]

    Demirel, Melik C.

    conferences and site visit to gather data. · Collect customer needs and engineering requirements. · MakePENNSTATE Department of XXXX Engineering Fall 2011 Harris2- Harnessing Human Energy Overview

  10. A review of "Transformations of Love: The Friendship of Evelyn and Godolphin." by Frances Harris

    E-Print Network [OSTI]

    Joanne Van Der Woude

    2004-01-01T23:59:59.000Z

    in the history, the politics, or even, indeed, the literature of the time. Frances Harris. Transformations of Love: The Friendship of John Evelyn and Margaret Godolphin. Oxford: Oxford University Press, 2002. x + 330 pp. + 8 illus. $35.00. Review by JOANNE... VAN DER WOUDE, UNIVERSITY OF VIRGINIA. In Transformations of Love, Frances Harris reconsiders the notorious friendship between John Evelyn and Margaret Godolphin ?in the context of the post-Reformation debate concerning marriage and the much longer...

  11. Petrology and diagenesis of the Lower Wilcox sandstones, North Milton field area, Harris County, Texas

    E-Print Network [OSTI]

    Miller, Gregory Radford

    1982-01-01T23:59:59.000Z

    PETROLOGY AND DIAGENESIS OF THE LOWER WILCOX SANDSTONES, NORTH MILTON FIELD AREA, HARRIS COUNTY, TEXAS A Thesis by GREGORY RADFORD MILLER Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE December 198Z Major Subject: Geology PETROLOGY AND DIAGENESIS OF THE LOWER WILCOX SANDSTONES, NORTH MILTON FIELD AREA, HARRIS COUNTY, TEXAS A Thesis by GREGORY RADFORD MILLER Approved as to style and content by...

  12. A comparison study of gravid and under house CO2 mosquito traps in Harris County, Texas

    E-Print Network [OSTI]

    White, Stephanie Lyn

    2008-10-10T23:59:59.000Z

    outweighs the additional materials or labor required for their use in a successful surveillance program. v DEDICATION I dedicate this project to my husband, Mike and my family for all their love, and unwavering support and patience. Without... Traps in Harris County, Texas. (May 2008) Stephanie Lyn White, B.S.; B.S., Texas A&M University Chair of Advisory Committee: Dr. Michael P. Ward Harris County Mosquito Control Division (HCMCD) is responsible for surveillance of mosquito species...

  13. Global Warming: Connecting the Dots

    E-Print Network [OSTI]

    Hansen, James E.

    Global Warming: Connecting the Dots from Causes to Solutions* Jim Hansen 26 February 2007 National://www.columbia.edu/~jeh1/worldwatch_nov2006.pdf) 5. Communicating dangers and opportunities in global warming, Amer-16, 2006. (http://pubs.giss.nasa.gov/docs/2006/2006_Hansen.pdf) 8. Global warming: Connecting the dots from

  14. Nanoscale engineering boosts performance of quantum dot light...

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

    Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission...

  15. DOT`s perspective on in-line inspection

    SciTech Connect (OSTI)

    Ulrich, L.W. [Dept. of Transportation, Washington, DC (United States). Office of Pipeline Safety

    1996-12-01T23:59:59.000Z

    The US Department of Transportation (DOT) and its Office of Pipeline Safety (OPS) have been involved with in-line inspection (ILI) pigs since the construction of the Alaska crude oil pipeline. Congressionally mandated reports concerning ILI pigs, and a regulation requiring new and replaced pipe and components be designed and constructed to accommodate ILI pigs, were issued by DOT. DOT also may mandate ILI pigs to be run on some pipelines. There is no current federal requirement to run ILI pigs. They are required by OPS in selected compliance cases. DOT supports future ILI pig research. The use of ILI pig surveys, incorporated in pipeline operators` future risk management plans developed as safety alternatives to the established pipeline safety regulations, will be supported.

  16. Nanophotonic design principles for ultrahigh efficiency photovoltaics Harry Atwater, Albert Polman, Emily Kosten, Dennis Callahan, Pierpaolo Spinelli, Carissa Eisler, Matthew

    E-Print Network [OSTI]

    Atwater, Harry

    Nanophotonic design principles for ultrahigh efficiency photovoltaics Harry Atwater, Albert Polman for ultrahigh efficiency photovoltaics Harry Atwater, 1,2 Albert Polman,2,1 , Emily Kosten, Dennis Callahan1 can enable ultrahigh efficiencies previously considered to be out of reach. Photovoltaic technology

  17. Read: Entrancing Enchantment: How Harry Cast a Spell Over Hip Nepali Readers

    E-Print Network [OSTI]

    Fineprint Bookclub

    2007-01-01T23:59:59.000Z

    bookstores were probably sekuwa pasals. Today, if a kid cannot find the Harry Potter edition that he wants at one bookstore, he can scoot around town and try his luck elsewhere. Harry Potter books also probably do well in Nepal because the books fill a... hundred seventy-fi ve students from different schools in the region, 1026 households, and offi cers from ten offi ces have become members of the library Each household, depending on its economic status, is charged from a minimum of 25 rupees to a...

  18. Hollow structures with bilayer graphene walls Peter J.F. Harris *

    E-Print Network [OSTI]

    Harris, Peter J F

    Hollow structures with bilayer graphene walls Peter J.F. Harris * Centre for Advanced Microscopy, J-discharge [7,8]. This new carbon apparently consists of hollow graphitic shells bounded by curved and faceted with nano-scale carbon particles, or short nanotubes; in some cases, nanotubes are found to be seamlessly

  19. Tissue-specific gene delivery via nanoparticle coating Todd J. Harris a,1

    E-Print Network [OSTI]

    Bhatia, Sangeeta

    Tissue-specific gene delivery via nanoparticle coating Todd J. Harris a,1 , Jordan J. Green b,1 delivery to the spleen and bone marrow. Thus, vari- ations in nanoparticle peptide coating density can Accepted 5 October 2009 Available online 21 October 2009 Keywords: Nanoparticle Targeting Gene delivery

  20. Fractal dimension unscreened angles measured for radial viscous fingering Olivier Praud Harry Swinney

    E-Print Network [OSTI]

    Texas at Austin. University of

    Fractal dimension unscreened angles measured for radial viscous fingering Olivier Praud Harry, USA #Received November 2004; published July 2005# have examined fractal patterns formed injection experiments. fractal dimension D 0 of pattern large r / 1.70±0.02. Further, generalized dimensions D pattern

  1. Grant Title: HARRY FRANK GUGGENHEIM FOUNDATION DISSERTATION FELLOWSHIP Funding Opportunity Number: N/A

    E-Print Network [OSTI]

    Farritor, Shane

    Grant Title: HARRY FRANK GUGGENHEIM FOUNDATION DISSERTATION FELLOWSHIP Funding Opportunity Number are entering the dissertation stage of graduate school. Summary: Ten or more dissertation fellowships are awarded each year to graduate students who would complete the writing of a dissertation within the award

  2. Water Conservation in the Home Janie L. Harris, M.Ed., CRS

    E-Print Network [OSTI]

    Water Conservation in the Home Janie L. Harris, M.Ed., CRS Extension Housing and Environment't Let the Faucet Run Dry Water Conservation in the Home Page 1Family and Consumer Sciences · Texas A&M AgriLife Extension Service A typical family uses 60­80 gallons of water per person per day. That's 240

  3. The transition to turbulence Harry L. Swinney and Jerry P. Gollub

    E-Print Network [OSTI]

    Texas at Austin. University of

    The transition to turbulence Harry L. Swinney and Jerry P. Gollub Citation: Phys. Today 31(8), 41://www.physicstoday.org/about_us/terms #12;The transition to turbulence Modern optical and computer techniques and new concepts in the theory- ically for more than a century and their equations of motion are well known, yet the transition from

  4. A dynamical definition of quasibound molecular clusters Sarah A. Harris and Ian J. Forda)

    E-Print Network [OSTI]

    Ford, Ian

    A dynamical definition of quasibound molecular clusters Sarah A. Harris and Ian J. Forda of a quasibound cluster are identified through a retrospective dynamical definition. The trajectory of a molecular is satisfied, however, at the instant that the energy of the departing molecule in the center of mass frame

  5. The Harris Foundation Student Application Form 1 Informacin de Aplicacin de estudiante 2013

    E-Print Network [OSTI]

    Rohs, Remo

    Acampe Información: El campamento de ciencia de ExxonMobil Bernard Harris (EMBHSSC) en el verano es que entran al 6, 7, o 8 grado en el Otoño de 2013. El campamento promueve la ciencia, la tecnología 7 grado que tienen interés en la ciencia y matemáticas y por lo menos un promedio "B" en la ciencia

  6. The Harris Foundation Estudiante Formulario de Solicitud 1 Informacin de Aplicacin de estudiante 2014

    E-Print Network [OSTI]

    Zhou, Chongwu

    2014 Acampe Información: El campamento de ciencia de ExxonMobil Bernard Harris (EMBHSSC) en el verano, o 8 grado en el Otoño de 2014. El campamento promueve la ciencia, la tecnología, la ingeniería, y tienen interés en la ciencia y matemáticas y por lo menos un promedio "B" en la ciencia y matemáticas son

  7. Pollution Prevention Through Productivity Improvement Harry W. Edwards, Michael F. Kostrzewa, and Cynthia K. Ketzenberger

    E-Print Network [OSTI]

    1 Pollution Prevention Through Productivity Improvement 99-151 Harry W. Edwards, Michael F that recommended productivity improvement practices can also prevent formation of wastes and polluting emissions. A total of 61 productivity improvement recommendations were made, 14 of which provide pollution prevention

  8. THE HOMOLOGOUS TEMPERATURE DEPENDENCE OF CREEP Harry W. Green, II and Robert S. Borch

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    709 THE HOMOLOGOUS TEMPERATURE DEPENDENCE OF CREEP Harry W. Green, II and Robert S. Borch of usually less than 10K. This apparatus has allowed us to test experimentally the prevailing philosophy that the pressure dependence of power law creep can be expressed by an activation volume, QV*, that approximates

  9. N E W S R E L E A S E Melissa Harris-Perry

    E-Print Network [OSTI]

    Akhmedov, Azer

    . Not a traditional political science work concerned with office-seeking, voting, or ideology, Sister Citizen insteadN E W S R E L E A S E Melissa Harris-Perry Sister Citizen: Shame, Stereotypes, and Black Women Pavilion · Courtesy of The Book Den, copies of Sister Citizen will be available for purchase and signing

  10. August 31, 2000 1 EE371: Advanced VLSI Circuit Design David Harris

    E-Print Network [OSTI]

    Harris, David Money

    August 31, 2000 1 EE371: Advanced VLSI Circuit Design David Harris Interconnect Delay Modeling delay (ps/µm) as a function of process parameters at the optimal sizing. First order analysis We begin is negligible · Inverters are sized for equal rise and fall times (faster results may be possible with unequal

  11. Aircraft Accident Prevention: Loss-of-Control Analysis Harry G. Kwatny

    E-Print Network [OSTI]

    Kwatny, Harry G.

    Aircraft Accident Prevention: Loss-of-Control Analysis Harry G. Kwatny , Jean-Etienne T. Dongmo NASA Langley Research Center, MS 161, Hampton, VA, 23681. The majority of fatal aircraft accidents that during the ten year period 1997-2006, 59% of fatal aircraft accidents were associated with Loss

  12. Double superexchange in quantum dot mesomaterials

    E-Print Network [OSTI]

    Wu, Zhigang

    of defects,2 and resist oxidation better.3 In addition, these small dots use their slice of the solar. An idea that has been explored for larger dots is to encapsulate them within an inorganic amorphous matrix yet to be achieved. A second approach is to encapsulate the dots within an organic polymer blend.12

  13. Modeling of the quantum dot filling and the dark current of quantum dot infrared photodetectors

    SciTech Connect (OSTI)

    Ameen, Tarek A.; El-Batawy, Yasser M.; Abouelsaood, A. A. [Department of Engineering Mathematics and Physics, Faculty of Engineering, Cairo University, Giza (Egypt)

    2014-02-14T23:59:59.000Z

    A generalized drift-diffusion model for the calculation of both the quantum dot filling profile and the dark current of quantum dot infrared photodetectors is proposed. The confined electrons inside the quantum dots produce a space-charge potential barrier between the two contacts, which controls the quantum dot filling and limits the dark current in the device. The results of the model reasonably agree with a published experimental work. It is found that increasing either the doping level or the temperature results in an exponential increase of the dark current. The quantum dot filling turns out to be nonuniform, with a dot near the contacts containing more electrons than one in the middle of the device where the dot occupation approximately equals the number of doping atoms per dot, which means that quantum dots away from contacts will be nearly unoccupied if the active region is undoped.

  14. Ionbombardmentenhanced grain growth in germanium, silicon, and gold Harry A. Atwater, Carl V. Thompson, and Henry I. Smith

    E-Print Network [OSTI]

    Atwater, Harry

    , Carl V. Thompson, and Henry I. Smith Citation: J. Appl. Phys. 64, 2337 (1988); doi: 10..bombardment..enhanced grain growth in germanium, silicon, and gold thin films Harry A. Atwater,a) Carl V. Thompson

  15. The status of resistance in Culex quinquefasciatus say (Diptera: culicidae) populations in Brazos and Harris Counties, Texas

    E-Print Network [OSTI]

    Johnsen, Mark Miller

    2009-05-15T23:59:59.000Z

    , and pyrethrum) used most frequently in adult mosquito control programs. The resistance ratios acquired from the vial bioassay tests were mapped onto shapefiles for Harris and Brazos counties, which revealed clustering of areas with pyrethroid resistance mosquito...

  16. A Week in LA, or, Dirty Harry Meets Starsky and Hutch

    E-Print Network [OSTI]

    Arenas, M.

    1980-01-01T23:59:59.000Z

    ? Looks more like mangling." A grin mellowed the words. "I was pretending it was Bressler* s face/' snapped Callahan, twisting an undershirt in his hands for emphasis. The young man's smile faded, his blue eyes looking huge behind wire-frame glasses... as two young men in faded blue jeans strolled up before him. "Inspector Harry Callahan," the captain was saying. "Detective Sergeants David Starsky and Kenneth Hutchinson." Starsky, the dark-haired man closest to him, extended his hand, but Callahan...

  17. Pervious Pavement A Strategic Plan For NYC DOT

    E-Print Network [OSTI]

    Qian, Ning

    Pervious Pavement A Strategic Plan For NYC DOT Presented By: Rene Brana Spring 2012 Capstone: Pervious Pavement - A Strategic Plan for NYC DOT 2 Capstone: Pervious Pavement - A Strategic Plan for NYC DOT 3 Image courtesy of

  18. Dynamics of Quantum Dot Photonic Crystal Lasers

    E-Print Network [OSTI]

    Bryan Ellis; Ilya Fushman; Dirk Englund; Bingyang Zhang; Yoshihisa Yamamoto; Jelena Vuckovic

    2007-03-07T23:59:59.000Z

    Quantum dot photonic crystal membrane lasers were fabricated and the large signal modulation characteristics were studied. We find that the modulation characteristics of quantum dot lasers can be significantly improved using cavities with large spontaneous emission coupling factor. Our experiments show, and simulations confirm, that the modulation rate is limited by the rate of carrier capture into the dots to around 30GHz in our present system.

  19. Quantum Dot Light Emitting Diode

    SciTech Connect (OSTI)

    Kahen, Keith

    2008-07-31T23:59:59.000Z

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  20. Quantum Dot Light Emitting Diode

    SciTech Connect (OSTI)

    Keith Kahen

    2008-07-31T23:59:59.000Z

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  1. Electron counting in quantum dots

    E-Print Network [OSTI]

    Fominov, Yakov

    source drain pg M. Sigrist Ciorga et al., PRB 61, R16315 (2000) Elzerman et al. PRB 67, 161308 (2003) #12 extreme near field optics #12;Photons or phonons? GaAs InAs Gustavsson et al., PRB 78, 035324 (2008) #12S. Schnez et al. PRB 78 (2008) 140 nm circular dot 1000-100-200 Energy (meV) 0 2 4 6 8 B(T) 0 100 200

  2. Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics

    E-Print Network [OSTI]

    Padilla, Derek

    2013-01-01T23:59:59.000Z

    4.4 Photovoltaics in Practice . . . . . . . . . . . . . .milestones. Quantum dot photovoltaics is in the bottom-rightIN QUANTUM DOT PHOTOVOLTAICS A dissertation submitted in

  3. Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics

    E-Print Network [OSTI]

    Padilla, Derek

    2013-01-01T23:59:59.000Z

    cell efficiency milestones. Quantum dot photovoltaics is inphotovoltaics provide the potential to create high-efficiencycell efficiency milestones. Quantum dot photovoltaics is in

  4. Single-dot optical emission from ultralow density well-isolated InP quantum dots

    SciTech Connect (OSTI)

    Ugur, A.; Hatami, F.; Masselink, W. T. [Department of Physics, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany); Vamivakas, A. N.; Lombez, L.; Atatuere, M. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2008-10-06T23:59:59.000Z

    We demonstrate a straightforward way to obtain single well-isolated quantum dots emitting in the visible part of the spectrum and characterize the optical emission from single quantum dots using this method. Self-assembled InP quantum dots are grown using gas-source molecular-beam epitaxy over a wide range of InP deposition rates, using an ultralow growth rate of about 0.01 atomic monolayers/s, a quantum-dot density of 1 dot/{mu}m{sup 2} is realized. The resulting isolated InP quantum dots embedded in an InGaP matrix are individually characterized without the need for lithographical patterning and masks on the substrate. Such low-density quantum dots show excitonic emission at around 670 nm with a linewidth limited by instrument resolution. This system is applicable as a single-photon source for applications such as quantum cryptography.

  5. Toolbox Safety Talk DOT Materials of Trade

    E-Print Network [OSTI]

    Pawlowski, Wojtek

    Toolbox Safety Talk DOT ­ Materials of Trade Environmental Health & Safety Facilities Safety by Trades personnel that meet the definition of hazardous materials even though they may be sold as consumer commodities. The DOT regulations have exceptions for Materials of Trade (MOT). The MOT exception provides

  6. Thick-shell nanocrystal quantum dots

    DOE Patents [OSTI]

    Hollingsworth, Jennifer A. (Los Alamos, NM); Chen, Yongfen (Eugene, OR); Klimov, Victor I. (Los Alamos, NM); Htoon, Han (Los Alamos, NM); Vela, Javier (Los Alamos, NM)

    2011-05-03T23:59:59.000Z

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  7. Lovell, J. E. J. 1997, PhD thesis, University of Tasmania Marshall, H. L., Harris, D. E., Grimes, J. P., Drake, J. J., Frus-

    E-Print Network [OSTI]

    Gelbord, Jonathan

    References Lovell, J. E. J. 1997, PhD thesis, University of Tasmania Marshall, H. L., Harris, D. EJ, 549, L167 Marshall, H. L., Miller, B. P., Davis, D. S., Perlman, E. S., Wise, M., Canizares, C. R., & Harris, D. E. 2002, ApJ, 564, 683 Marshall, H. L., Schwartz, D. A., Worrall, D. M., Birkinshaw, M

  8. Towards an ISO standard for dialogue act annotation Harry Bunt*, Jan Alexandersson, Jean Carletta, Jae-Woong Choe, Alex Chengyu Fang,

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Towards an ISO standard for dialogue act annotation Harry Bunt*, Jan Alexandersson, Jean Carletta University, The Netherlands harry.bunt@uvt.nl Abstract This paper describes an ISO project developing to what was said and done earlier in the dialogue. The project, registered as ISO 24617-2 Semantic

  9. The Chemical Composition of Soils of Cameron, Coleman, Dallas, Erath, Harris, Reeves, Rockwall and Tarrant Counties.

    E-Print Network [OSTI]

    Fraps, G. S. (George Stronach)

    1931-01-01T23:59:59.000Z

    the relative deficiencies of plant food in the soil. The corn possibility is also a convenient way of comparing amounts of various plant foods in the same soil. For example, with the Lake Charles clay loam of Harris county, the corn possibility for total... nitrogen is 28, for active phos- phoric acid is 12, and for the active potash 50. The soil is probably deficient both in phosphoric acid and in nitrogen. This may he com- pared with the Victoria clay loam of Cameron countv, which has a corn possibility...

  10. Phonon Mediated Off-Resonant Quantum Dot-Cavity Coupling

    E-Print Network [OSTI]

    Arka Majumdar; Yiyang Gong; Erik D. Kim; Jelena Vuckovic

    2010-12-14T23:59:59.000Z

    A theoretical model for the phonon-mediated off-resonant coupling between a quantum dot and a cavity, under resonant excitation of the quantum dot, is presented. We show that the coupling is caused by electron-phonon interaction in the quantum dot and is enhanced by the cavity. We analyze recently observed resonant quantum dot spectroscopic data by our theoretical model.

  11. Walking the Walk: Making DOE Management and Operations More Efficient...

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

    July 2, 2012 - 3:03pm Addthis Beth Tomasoni was part of a team from the Office of Management that included Richard Leotta and John Harris who improved diversity and...

  12. Semiconductor Quantum Dots and Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells

    E-Print Network [OSTI]

    George, Steven C.

    to Third-Generation Photovoltaic Solar Cells A. J. Nozik,*,, M. C. Beard, J. M. Luther, M. Law,§ R. J. Applications: Quantum Dot Solar Cells 6884 6.1. Quantum Dot Solar Cell Configurations 6885 6.1.1. Photoelectrodes Composed of Quantum Dot Arrays 6885 6.1.2. Quantum Dot-Sensitized Nanocrystalline TiO2 Solar Cells

  13. An Analysis of Facebook Photo Caching Qi Huang, Ken Birman, Robbert van Renesse, Wyatt Lloyd, Sanjeev Kumar, Harry C. Li

    E-Print Network [OSTI]

    Keinan, Alon

    An Analysis of Facebook Photo Caching Qi Huang, Ken Birman, Robbert van Renesse, Wyatt Lloyd, Sanjeev Kumar, Harry C. Li Cornell University, Princeton University, Facebook Inc. Abstract This paper examines the workload of Facebook's photo- serving stack and the effectiveness of the many layers

  14. came to the museum after his death.The Galapagos finches,collected on the Beagle voyage by Harry Fuller,

    E-Print Network [OSTI]

    came to the museum after his death.The Galapagos finches,collected on the Beagle voyage by Harry Fuller, came to the museum by a convoluted route,the eight birds he collected first being given or sold to Dr Armstrong of the Haslar Museum, part of the Royal Naval Hospital in Portsmouth. On the closure

  15. The Role of Climatic and Environmental Variability on West Nile Virus in Harris County, Texas, 2006-2007

    E-Print Network [OSTI]

    Berhane, Stephen

    2010-07-14T23:59:59.000Z

    Between the years 2006-2007, Harris County, located at the heart of the Houston metropolitan area, experienced a nearly 90% decline in the number of female mosquitoes which tested positive for the West Nile virus. Different theories exist as to why...

  16. Light-Induced Frequency Shift in Chemical Spirals Valery Petrov, Qi Ouyang, Ge Li, and Harry L. Swinney*

    E-Print Network [OSTI]

    Texas at Austin. University of

    Light-Induced Frequency Shift in Chemical Spirals Valery Petrov, Qi Ouyang, Ge Li, and Harry L-Tyson relation for the spirals, D /3k2 , is independent of light intensity (D ) 2.5 × 10-6 cm2 /s). Introduction The light-sensitive Belousov-Zhabotinsky (BZ) reaction with a ruthenium-based catalyst is a convenient

  17. Harmonic generation by reflecting internal waves Bruce Rodenborn, D. Kiefer, H. P. Zhang, and Harry L. Swinney

    E-Print Network [OSTI]

    Texas at Austin. University of

    Harmonic generation by reflecting internal waves Bruce Rodenborn, D. Kiefer, H. P. Zhang, and Harry harmonics and mixing. We use laboratory experiments and two-dimensional numerical simulations of the Navier harmonic waves in the reflection process. The results from our experiments and simulations agree well

  18. Photodetectors based on colloidal quantum dots

    E-Print Network [OSTI]

    Oertel, David C. (David Charles)

    2007-01-01T23:59:59.000Z

    Inspired by recent work demonstrating photocurrent enhancement in quantum-dot (QD) solids via post-deposition chemical annealing and by recent successes incorporating single monolayers of QDs in light-emitting devices ...

  19. Synthesis and characterization of infrared quantum dots

    E-Print Network [OSTI]

    Harris, Daniel Kelly

    2014-01-01T23:59:59.000Z

    This thesis focuses on the development of synthetic methods to create application ready quantum dots (QDs) in the infrared for biological imaging and optoelectronic devices. I concentrated primarily on controlling the size ...

  20. Thermoelectric transport through strongly correlated quantum dots

    E-Print Network [OSTI]

    T. A. Costi; V. Zlatic

    2010-07-08T23:59:59.000Z

    The thermoelectric properties of strongly correlated quantum dots, described by a single level Anderson model coupled to conduction electron leads, is investigated using Wilson's numerical renormalization group method. We calculate the electronic contribution, $K_{\\rm e}$, to the thermal conductance, the thermopower, $S$, and the electrical conductance, $G$, of a quantum dot as a function of both temperature, $T$, and gate voltage, ${\\rm v}_g$, for strong, intermediate and weak Coulomb correlations, $U$, on the dot. For strong correlations and in the Kondo regime, we find that the thermopower exhibits two sign changes, at temperatures $T_{1}({\\rm v}_g)$ and $T_{2}({\\rm v}_g)$ with $T_{1}< T_{2}$. Such sign changes in $S(T)$ are particularly sensitive signatures of strong correlations and Kondo physics. The relevance of this to recent thermopower measurements of Kondo correlated quantum dots is discussed. We discuss the figure of merit, power factor and the degree of violation of the Wiedemann-Franz law in quantum dots. The extent of temperature scaling in the thermopower and thermal conductance of quantum dots in the Kondo regime is also assessed.

  1. Nanostructured architectures for colloidal quantum dot solar cells

    E-Print Network [OSTI]

    Jean, Joel, S.M. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    This thesis introduces a novel ordered bulk heterojunction architecture for colloidal quantum dot (QD) solar cells. Quantum dots are solution-processed nanocrystals whose tunable bandgap energies make them a promising ...

  2. Electron tunneling and spin relaxation in a lateral quantum dot

    E-Print Network [OSTI]

    Amasha, Sami

    2008-01-01T23:59:59.000Z

    We report measurements that use real-time charge sensing to probe a single-electron lateral quantum dot. The charge sensor is a quantum point contact (QPC) adjacent to the dot and the sensitivity is comparable to other ...

  3. Fast quantum dot single photon source triggered at telecommunications wavelength

    E-Print Network [OSTI]

    Kelley Rivoire; Sonia Buckley; Arka Majumdar; Hyochul Kim; Pierre Petroff; Jelena Vuckovic

    2010-12-20T23:59:59.000Z

    We demonstrate a quantum dot single photon source at 900 nm triggered at 300 MHz by a continuous wave telecommunications wavelength laser followed by an electro-optic modulator. The quantum dot is excited by on-chip-generated second harmonic radiation, resonantly enhanced by a GaAs photonic crystal cavity surrounding the InAs quantum dot. Our result suggests a path toward the realization of telecommunications-wavelength-compatible quantum dot single photon sources with speeds exceeding 1 GHz.

  4. Mini Review Water-soluble quantum dots for biomedical applications

    E-Print Network [OSTI]

    ­emission matrix (EEM) reveals that quantum dots always emit the same lights no matter what excita- tion wavelength

  5. Thermoelectric transport through strongly correlated quantum dots

    E-Print Network [OSTI]

    Costi, T A; 10.1103/PhysRevB.81.235127

    2010-01-01T23:59:59.000Z

    The thermoelectric properties of strongly correlated quantum dots, described by a single level Anderson model coupled to conduction electron leads, is investigated using Wilson's numerical renormalization group method. We calculate the electronic contribution, $K_{\\rm e}$, to the thermal conductance, the thermopower, $S$, and the electrical conductance, $G$, of a quantum dot as a function of both temperature, $T$, and gate voltage, ${\\rm v}_g$, for strong, intermediate and weak Coulomb correlations, $U$, on the dot. For strong correlations and in the Kondo regime, we find that the thermopower exhibits two sign changes, at temperatures $T_{1}({\\rm v}_g)$ and $T_{2}({\\rm v}_g)$ with $T_{1}law in ...

  6. Electron Transfer to SF6 and Oriented CH3Br Sean A. Harris, Susan D. Wiediger, and Philip R. Brooks*

    E-Print Network [OSTI]

    Brooks, Philip R.

    ARTICLES Electron Transfer to SF6 and Oriented CH3Br Sean A. Harris, Susan D. Wiediger, and Philip in collisions of unoriented SF6 and oriented CH3Br. For lab energies 5-30 eV, Br- is the only ion observed from the same energetic threshold for forming Br- . SF5 - , SF6 - , and F- ions are observed from SF6 and O2

  7. Engineered Quantum Dot Single Photon Sources

    E-Print Network [OSTI]

    Sonia Buckley; Kelley Rivoire; Jelena Vuckovic

    2012-10-03T23:59:59.000Z

    Fast, high efficiency, and low error single photon sources are required for implementation of a number of quantum information processing applications. The fastest triggered single photon sources to date have been demonstrated using epitaxially grown semiconductor quantum dots (QDs), which can be conveniently integrated with optical microcavities. Recent advances in QD technology, including demonstrations of high temperature and telecommunications wavelength single photon emission, have made QD single photon sources more practical. Here we discuss the applications of single photon sources and their various requirements, before reviewing the progress made on a quantum dot platform in meeting these requirements.

  8. Bilayer graphene quantum dot defined by topgates

    SciTech Connect (OSTI)

    Müller, André; Kaestner, Bernd; Hohls, Frank; Weimann, Thomas; Pierz, Klaus; Schumacher, Hans W., E-mail: hans.w.schumacher@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)

    2014-06-21T23:59:59.000Z

    We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK, the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.

  9. Synthesis of CdSe quantum dots for quantum dot sensitized solar cell

    SciTech Connect (OSTI)

    Singh, Neetu, E-mail: singh.neetu1985@gmail.com; Kapoor, Avinashi [Department of Electronic Science, University of Delhi South Campus, New Delhi-110 021 (India); Kumar, Vinod [Department of Physics, University of the Free State, Bloemfontein, ZA9300 (South Africa); Mehra, R. M. [School of Engineering and Technology, Sharda University, Greater Noida-201 306, U.P. (India)

    2014-04-24T23:59:59.000Z

    CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5.

  10. Mn/DOT's Project Peer Review

    E-Print Network [OSTI]

    Minnesota, University of

    and sustain this culture #12;Project Management #12;Recent National Work in Transportation Project ManagementMn/DOT's Project Management Peer Review Creating a Project Management Culture 2010 CTS Research a Peer Review? Why Project Management? ·Improve project delivery performance ­ on time, on budget (an

  11. Spin dynamics characterization in magnetic dots

    E-Print Network [OSTI]

    Mozaffari, Mohammad Reza; Esfarjani, Keivan

    2007-01-01T23:59:59.000Z

    J= 0.1 meV Frequency (JS) SDF J=0.6 meV Fig. 2. (Colorfrom diagonalization (SDF: J=1 eV) Frequency spectrum fromMagnon DOS for a circular dot SDF: J=0.6 meV N=1600 N=400 N=

  12. Watch for the red dot indicating

    E-Print Network [OSTI]

    > http:// > Watch for the red dot indicating expanded stories online sdm.mit.edu/pulse continued its facilities by constructing the European Extremely Large Telescope (E-ELT) on a mountain in Chile isolated from the grid. The planned construction of the E-ELT and the challenges faced by the current

  13. Enhanced Joule Heating in Umbral Dots

    E-Print Network [OSTI]

    Chandan Joshi; Lokesh Bharti; S. N. A. Jaaffrey

    2007-05-10T23:59:59.000Z

    We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.

  14. Deposition of colloidal quantum dots by microcontact printing for LED display technology

    E-Print Network [OSTI]

    Kim, LeeAnn

    2006-01-01T23:59:59.000Z

    This thesis demonstrates a new deposition method of colloidal quantum dots within a quantum dot organic light-emitting diode (QD-LED). A monolayer of quantum dots is microcontact printed as small as 20 ,Lm lines as well ...

  15. An environmental impact assessment of quantum dot photovoltaics (QDPV) from raw material acquisition through use

    E-Print Network [OSTI]

    Illinois at Chicago, University of

    An environmental impact assessment of quantum dot photovoltaics (QDPV) from raw material of Environmental Engineering, Beytepe, Ankara, Turkey b Institute for Environmental Science and Policy, University: Life cycle assessment Quantum dots Nanophotovoltaics Quantum dot photovoltaic modules Solar energy

  16. Elastic fields of quantum dots in subsurface layers A. E. Romanov

    E-Print Network [OSTI]

    Beltz, Glenn E.

    to vertical stacking of dots provided that the thickness of the intervening layer ``spacer layer'' is in the order or thinner than the lateral dimensions of the dot.4 It is now clear that dot ordering is driven

  17. Controlling quantum dot energies using submonolayer bandstructure engineering

    SciTech Connect (OSTI)

    Yu, L.; Law, S.; Wasserman, D. [Department of Electrical and Computer Engineering, University of Illinois Urbana Champaign, Urbana, Illinois 61801 (United States); Jung, D.; Lee, M. L. [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520 (United States); Shen, J.; Cha, J. J. [Department of Mechanical Engineering and Materials Science and Energy Science Institute, Yale University, New Haven, Connecticut 06520 (United States)

    2014-08-25T23:59:59.000Z

    We demonstrate control of energy states in epitaxially-grown quantum dot structures formed by stacked submonolayer InAs depositions via engineering of the internal bandstructure of the dots. Transmission electron microscopy of the stacked sub-monolayer regions shows compositional inhomogeneity, indicative of the presence of quantum dots. The quantum dot ground state is manipulated not only by the number of deposited InAs layers, but also by control of the thickness and material composition of the spacing layers between submonolayer InAs depositions. In this manner, we demonstrate the ability to shift the quantum dot ground state energy at 77?K from 1.38?eV to 1.88?eV. The results presented offer a potential avenue towards enhanced control of dot energies for a variety of optoelectronic applications.

  18. Local Quantum Dot Tuning on Photonic Crystal Chips

    E-Print Network [OSTI]

    Andrei Faraon; Dirk Englund; Ilya Fushman; Nick Stoltz; Pierre Petroff; Jelena Vuckovic

    2007-03-28T23:59:59.000Z

    Quantum networks based on InGaAs quantum dots embedded in photonic crystal devices rely on QDs being in resonance with each other and with the cavities they are embedded in. We developed a new technique based on temperature tuning to spectrally align different quantum dots located on the same chip. The technique allows for up to 1.8nm reversible on-chip quantum dot tuning.

  19. Steering of a Bosonic Mode with a Double Quantum Dot

    E-Print Network [OSTI]

    T. Brandes; N. Lambert

    2003-02-13T23:59:59.000Z

    We investigate the transport and coherence properties of a double quantum dot coupled to a single damped boson mode. Our numerically results reveal how the properties of the boson distribution can be steered by altering parameters of the electronic system such as the energy difference between the dots. Quadrature amplitude variances and the Wigner function are employed to illustrate how the state of the boson mode can be controlled by a stationary electron current through the dots.

  20. Separability and dynamical symmetry of Quantum Dots

    SciTech Connect (OSTI)

    Zhang, P.-M., E-mail: zhpm@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou (China); Zou, L.-P., E-mail: zoulp@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou (China); Horvathy, P.A., E-mail: horvathy@lmpt.univ-tours.fr [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou (China); Laboratoire de Mathématiques et de Physique Théorique, Tours University (France); Gibbons, G.W., E-mail: G.W.Gibbons@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, Cambridge University, Cambridge (United Kingdom)

    2014-02-15T23:59:59.000Z

    The separability and Runge–Lenz-type dynamical symmetry of the internal dynamics of certain two-electron Quantum Dots, found by Simonovi? et al. (2003), are traced back to that of the perturbed Kepler problem. A large class of axially symmetric perturbing potentials which allow for separation in parabolic coordinates can easily be found. Apart from the 2:1 anisotropic harmonic trapping potential considered in Simonovi? and Nazmitdinov (2013), they include a constant electric field parallel to the magnetic field (Stark effect), the ring-shaped Hartmann potential, etc. The harmonic case is studied in detail. -- Highlights: • The separability of Quantum Dots is derived from that of the perturbed Kepler problem. • Harmonic perturbation with 2:1 anisotropy is separable in parabolic coordinates. • The system has a conserved Runge–Lenz type quantity.

  1. Mastermind Session: Connecting the Dots Between the Real Estate...

    Energy Savers [EERE]

    and Residential Energy Efficiency Better Buildings Residential Network Program Sustainability Series Mastermind Call: Connecting the Dots Between the Real Estate Market and...

  2. alloy quantum dots: Topics by E-print Network

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

    Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells Biology and Medicine Websites Summary: to Third-Generation...

  3. assembled quantum dots: Topics by E-print Network

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

    Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells Biology and Medicine Websites Summary: to Third-Generation...

  4. anisn format dot: Topics by E-print Network

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

    Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells Biology and Medicine Websites Summary: to Third-Generation...

  5. asymmetry quantum dots: Topics by E-print Network

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

    Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells Biology and Medicine Websites Summary: to Third-Generation...

  6. How Analysts Cognitively “Connect the Dots

    SciTech Connect (OSTI)

    Bradel, Lauren; Self, Jessica S.; Endert, Alexander; Hossain, Shahriar M.; North, Chris; Ramakrishnan, Naren

    2013-06-04T23:59:59.000Z

    As analysts attempt to make sense of a collection of documents, such as intelligence analysis reports, they may wish to “connect the dots” between pieces of information that may initially seem unrelated. This process of synthesizing information between information requires users to make connections between pairs of documents, creating a conceptual story. We conducted a user study to analyze the process by which users connect pairs of documents and how they spatially arrange information. Users created conceptual stories that connected the dots using organizational strategies that ranged in complexity. We propose taxonomies for cognitive connections and physical structures used when trying to “connect the dots” between two documents. We compared the user-created stories with a data-mining algorithm that constructs chains of documents using co-occurrence metrics. Using the insight gained into the storytelling process, we offer design considerations for the existing data mining algorithm and corresponding tools to combine the power of data mining and the complex cognitive processing of analysts.

  7. Photovoltaic performance of ultra-small PbSe quantum dots

    E-Print Network [OSTI]

    Ma, Wanli

    2014-01-01T23:59:59.000Z

    Colloidal Quantum Dots for Photovoltaics: Fundamentals andSchottky-Quantum Dot Photovoltaics for Efficient InfraredDJ; Klimov, VI, Hybrid Photovoltaics Based on Semiconductor

  8. State DOT: PENNSYLVANIA State Report Questions on NDT Testing

    E-Print Network [OSTI]

    capacity surveys, management of load restrictions, fatigue tests and compaction control. On concreteState DOT: PENNSYLVANIA State Report Questions on NDT Testing 1. What NDT testing methods for concrete materials, concrete pavements, and overlays are you trying? PennDOT performs Falling Weight

  9. State DOT: Missouri State Report Questions on NDT Testing

    E-Print Network [OSTI]

    State DOT: Missouri State Report Questions on NDT Testing 1. What NDT testing methods for concrete maturity meter MoDOT has utilized the rebound hammer to evaluate in-place concrete when cylinder testing materials, concrete pavements, and overlays are you trying? a) Maturity Method b) Rebound Hammer c) Cover

  10. Manipulating Quantum Dots to Nanometer Precision by Control of Flow

    E-Print Network [OSTI]

    Waks, Edo

    Manipulating Quantum Dots to Nanometer Precision by Control of Flow Chad Ropp, Roland Probst on the dynamically manipulated QD. KEYWORDS Quantum dots, control, electroosmotic flow, subpixel averaging, photon of Standards and Technology, Gaithersburg, Maryland 20899 ABSTRACT We present a method for manipulating

  11. Minnesota Guidestar www.dot.state.mn.us/guidestar

    E-Print Network [OSTI]

    Minnesota, University of

    .dot.state.mn.us/guidestar What is ITS? · Application of technology to improve the safety and efficiency of the transportation system. #12;Minnesota Guidestar www.dot.state.mn.us/guidestar What is ITS? · Traffic Management ­ Signal Systems ­ Ramp Meters · Emergency Response ­ Mobile Data Terminals ­ 911 Dispatch ­ RF Data Networks

  12. State DOT: Michigan State Report Questions on MEPDG Implementation

    E-Print Network [OSTI]

    State DOT: Michigan State Report Questions on MEPDG Implementation 1. Summarize your state's status as far as MEPDG Implementation. Michigan DOT has purchased a single copy of DARWin-ME for the statewide, a research project will begin with Michigan State University involving local calibration and validation

  13. How to make dried blood dots for genetic studies

    E-Print Network [OSTI]

    Schall, Joseph J.

    How to make dried blood dots for genetic studies If a vertebrate is in-hand, and blood being taken, it is easy to make both a blood smear and dried blood dots. Modern research on malaria parasites demands that BOTH a blood smear and blood samples be taken. Blood can be stored in lysis buffers of various kinds

  14. Two-plasmon quantum interference James S. Fakonas1,2, Hyunseok Lee2, Yousif A. Kelaita2 and Harry A. Atwater1,2

    E-Print Network [OSTI]

    Atwater, Harry

    Two-plasmon quantum interference James S. Fakonas1,2, Hyunseok Lee2, Yousif A. Kelaita2 and Harry A­3 , with the surface plasmon, the quantum of the surface plasma wave, playing the same role as the photon. It follows that surface plasmons should exhibit all the same quantum phenomena that photons do. Here, we report a plas

  15. Modified Hard Magnets V. G. Harris and Christina Chen, Co-Chairmen Mossbauer spectroscopy study of the rhombohedral phase Y2Fe17Nx

    E-Print Network [OSTI]

    Yang, De-Ping

    Modified Hard Magnets V. G. Harris and Christina Chen, Co-Chairmen Mo¨ssbauer spectroscopy study 06269 Mo¨ssbauer spectra were obtained at 15 K from samples of rhombohedral Y2Fe17 and its nitrides Y2Fe there have been several previous reports of Mo¨ssbauer effect ME studies on Y2Fe17Nx , their main focus has

  16. Ge/SiGe Quantum Confined Stark Effect Modulators on Silicon James S. Harris, Yu-Hsuan Kuo, and David A. B. Miller

    E-Print Network [OSTI]

    Miller, David A. B.

    Ge/SiGe Quantum Confined Stark Effect Modulators on Silicon James S. Harris, Yu-Hsuan Kuo bandwidth have been demonstrated [4]. 2. Quantum well design Ge is an indirect band gap material, but it has. In order to have good quantum confinement, SiGe barriers are used since Si and Ge have a very high direct

  17. Magnetic Exchange Coupling in Actinide-Containing Molecules Jeffrey D. Rinehart, T. David Harris, Stosh A. Kozimor, Bart M. Bartlett, and Jeffrey R. Long*

    E-Print Network [OSTI]

    Harris, Stosh A. Kozimor, Bart M. Bartlett, and Jeffrey R. Long* Department of Chemistry, Uni magnetic exchange interactions, including multiuranium, uranium-lanthanide, uranium-transition metal, and uranium-radical species. Interpretation of the magnetic susceptibility data for compounds of this type

  18. Nontoxic quantum dot research improves solar cells

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated CodesTransparencyDOE Project Taps HPCNew4OrganicNontoxic quantum dot

  19. Temperature Dependence of Single CdSe/ZnS Quantum Dots Luminescence Lifetime

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    , such as quantum dots (QDs), has grown dramatically. These semiconductor QDs bridge the gap between single

  20. Competing interactions in semiconductor quantum dots

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

    van den Berg, R.; Brandino, G. P.; El Araby, O.; Konik, R. M.; Gritsev, V.; Caux, J. -S.

    2014-10-01T23:59:59.000Z

    We introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free induction decay and spin echo simulations we characterize the combined effect of both types of interactions on the decoherence of the electron spin, for external fields ranging from low to high values. We show that for spin echo simulations the hyperfine interaction is the dominant source of decoherence at short times for low fields, and competes with the dipole-dipole interactions at longer times. Onmore »the contrary, at high fields the main source of decay is due to the dipole-dipole interactions. In the latter regime an asymmetry in the echo is observed. Furthermore, the non-decaying fraction previously observed for zero field free induction decay simulations in quantum dots with only hyperfine interactions, is destroyed for longer times by the mean-field treatment of the dipolar interactions.« less

  1. Competing interactions in semiconductor quantum dots

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

    van den Berg, R. [Univ. of Amsterdam (Netherlands). Inst. for Theoretical Physics; Brandino, G. P. [Univ. of Amsterdam (Netherlands). Inst. for Theoretical Physics; El Araby, O. [Univ. of Amsterdam (Netherlands). Inst. for Theoretical Physics; Konik, R. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gritsev, V. [Univ. of Amsterdam (Netherlands). Inst. for Theoretical Physics; Caux, J. -S. [Univ. of Amsterdam (Netherlands). Inst. for Theoretical Physics

    2014-10-01T23:59:59.000Z

    We introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free induction decay and spin echo simulations we characterize the combined effect of both types of interactions on the decoherence of the electron spin, for external fields ranging from low to high values. We show that for spin echo simulations the hyperfine interaction is the dominant source of decoherence at short times for low fields, and competes with the dipole-dipole interactions at longer times. On the contrary, at high fields the main source of decay is due to the dipole-dipole interactions. In the latter regime an asymmetry in the echo is observed. Furthermore, the non-decaying fraction previously observed for zero field free induction decay simulations in quantum dots with only hyperfine interactions, is destroyed for longer times by the mean-field treatment of the dipolar interactions.

  2. Linewidth broadening of a quantum dot coupled to an off-resonant cavity

    E-Print Network [OSTI]

    Arka Majumdar; Andrei Faraon; Erik Kim; Dirk Englund; Hyochul Kim; Pierre Petroff; Jelena Vuckovic

    2010-03-11T23:59:59.000Z

    We study the coupling between a photonic crystal cavity and an off-resonant quantum dot under resonant excitation of the cavity or the quantum dot. Linewidths of the quantum dot and the cavity as a function of the excitation laser power are measured. We show that the linewidth of the quantum dot, measured by observing the cavity emission, is significantly broadened compared to the theoretical estimate. This indicates additional incoherent coupling between the quantum dot and the cavity.

  3. Federal Efficiency Program Wins GreenGov Dream Team Award | Department...

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

    - 11:53am Addthis Partnered with the Department of Transportation (DOT), EERE's Federal Energy Management Program (FEMP) won the GreenGov Presidential Green Dream Team Award. The...

  4. Coherent excitation of a strongly coupled quantum dot - cavity system

    E-Print Network [OSTI]

    Dirk Englund; Arka Majumdar; Andrei Faraon; Mitsuru Toishi; Nick Stoltz; Pierre Petroff; Jelena Vuckovic

    2009-02-19T23:59:59.000Z

    We have studied the coherent excitation of a strongly coupled QD/photonic crystal cavity system. Time-resolved reflectivity measurements show the vacuum Rabi oscillation of the dot in the cavity. Next, we considered the resonant driving of a cavity-detuned dot, which efficiently populates the cavity mode. This cavity-controlled read-out channel allows high-resolution single quantum dot spectroscopy. Autocorrelation measurements on the cavity mode show antibunching and suggest the use of the resonantly driven QD/cavity system as an on-demand source of single photons with potentially near-unity indistinguishability.

  5. Designing Small Silicon Quantum Dots with Low Reorganization Energy

    E-Print Network [OSTI]

    Zang, Xiaoning

    2015-01-01T23:59:59.000Z

    A first principles, excited state analysis is carried out to identify ways of producing silicon quantum dots with low excitonic reorganization energy. These focus on the general strategy of either reducing or constraining exciton-phonon coupling, and four approaches are explored. The results can be implemented in quantum dot solids to mitigate polaronic effects and increase the lifetime of coherent excitonic superpositions. It is demonstrated that such designs can also be used to alter the shape of the spectral density for reorganization so as to reduce the rates of both decoherence and dissipation. The results suggest that it may be possible to design quantum dot solids that support partially coherent exciton transport.

  6. Factorization of Dirac Equation and Graphene Quantum Dot

    E-Print Network [OSTI]

    Youness Zahidi; Ahmed Jellal; Hocine Bahlouli; Mohammed El Bouziani

    2014-05-14T23:59:59.000Z

    We consider a quantum dot described by a cylindrically symmetric 2D Dirac equation. The potentials representing the quantum dot are taken to be of different types of potential configuration, scalar, vector and pseudo-scalar to enable us to enrich our study. Using various potential configurations, we found that in the presence of a mass term an electrostatically confined quantum dot can accommodate true bound states, which is in agreement with previous work. The differential cross section associated with one specific potential configuration has been computed and discussed as function of the various potential parameters.

  7. The relevance of the effective school correlates, to alternative education settings, for student in a correctional system, as identified by the teachers and adminstrators in selected charter schools, in Harris County, Texas

    E-Print Network [OSTI]

    Cortez-Rucker, Vance

    2009-05-15T23:59:59.000Z

    was to assess the relevance of the Effective School Correlates to alternative educational settings for students in a correctional system as identified by the teachers and administrators in selected charter schools in Harris County, Texas. Secondly, the study...

  8. Application of Mn/DOT Utility Coordination Process to Local Agencies Based on national best practices, the Minnesota Department of Transportation (Mn/DOT) Utility

    E-Print Network [OSTI]

    Minnesota, University of

    Application of Mn/DOT Utility Coordination Process to Local Agencies Based on national best practices, the Minnesota Department of Transportation (Mn/DOT) Utility Coordination Process incorporates Processes There are projects where the full process is not necessary. The Mn/DOT Utilities Manual provides

  9. Temperature-Dependent Electron Transport in Quantum Dot Photovoltaics

    E-Print Network [OSTI]

    Padilla, Derek

    2013-01-01T23:59:59.000Z

    to enhanced photovoltaic device efficiency. ACS nano, 2(11):Photovoltaic Devices Introduction Thin-film quantum dot (QD) photovoltaics provide the potential to create high-efficiencyefficiency under such illumina- tion. A non-ideal model of a photovoltaic

  10. Cumulative Effects Guidance 2007 MnDOT Environmental

    E-Print Network [OSTI]

    Minnesota, University of

    relevant for actions requiring an environmental impact statement § Analysis for projects processed as EACumulative Effects Guidance 2007 MnDOT Environmental Stewardship & Streamlining Workshop Presented by Dave Gamble Federal Highway Administration Resource Center Environmental Technical Service Team #12

  11. Engineering a Robust Photovoltaic Device with Quantum Dots and Bacteriorhodopsin

    E-Print Network [OSTI]

    Renugopalakrishnan, Venkatesan

    We present a route toward a radical improvement in solar cell efficiency using resonant energy transfer and sensitization of semiconductor metal oxides with a light-harvesting quantum dot (QD)/bacteriorhodopsin (bR) layer ...

  12. Quantum Dot Tracers for Use in Engineered Geothermal Systems

    Broader source: Energy.gov [DOE]

    DOE Geothermal Peer Review 2010 - Presentation. Project objective: To develop and demonstrate a new class of tracers?semiconductor nanoparticles(quantum dots)?that offer great promise for use in characterizing fracture networks in EGS reservoirs.

  13. Quantum dot conjugates in a sub-micrometer fluidic channel

    DOE Patents [OSTI]

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2010-04-13T23:59:59.000Z

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  14. Self-Sustaining Dynamical Nuclear Polarization Oscillations in Quantum Dots

    E-Print Network [OSTI]

    Rudner, M. S.

    Early experiments on spin-blockaded double quantum dots revealed robust, large-amplitude current oscillations in the presence of a static (dc) source-drain bias. Despite experimental evidence implicating dynamical nuclear ...

  15. Study of field driven electroluminescence in colloidal quantum dot solids

    E-Print Network [OSTI]

    Bozyigit, Deniz

    Semiconductor nanocrystals, or quantum dots(QDs), promise to drive advances in electronic light generation. It was recently shown that long range transport of charge, which is typically required for electric excitation and ...

  16. Hybrid organic/quantum dot thin film structures and devices

    E-Print Network [OSTI]

    Coe-Sullivan, Seth (Seth Alexander)

    2005-01-01T23:59:59.000Z

    Organic light emitting diodes have undergone rapid advancement over the course of the past decade. Similarly, quantum dot synthesis has progressed to the point that room temperature highly efficient photoluminescence can ...

  17. Design and fabrication of quantum-dot lasers

    E-Print Network [OSTI]

    Nabanja, Sheila

    2008-01-01T23:59:59.000Z

    Semiconductor lasers using quantum-dots in their active regions have been reported to exhibit significant performance advantages over their bulk semiconductor and quantum-well counterparts namely: low threshold current, ...

  18. Scalable quantum computer architecture with coupled donor-quantum dot qubits

    DOE Patents [OSTI]

    Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey

    2014-08-26T23:59:59.000Z

    A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.

  19. Fluorescence from a quantum dot and metallic nanosphere hybrid system

    SciTech Connect (OSTI)

    Schindel, Daniel G. [Department of Mathematics and Statistics, University of Winnipeg, 515 Portage Avenue, Winnipeg, MB, R3B 2E9 (Canada); Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7 (Canada)

    2014-03-31T23:59:59.000Z

    We present energy absorption and interference in a quantum dot-metallic nanosphere system embedded on a dielectric substrate. A control field is applied to induce dipole moments in the nanosphere and the quantum dot, and a probe field is applied to monitor absorption. Dipole moments in the quantum dot or the metal nanosphere are induced, both by the external fields and by each other's dipole fields. Thus, in addition to direct polarization, the metal nanosphere and the quantum dot will sense one another via the dipole-dipole interaction. The density matrix method was used to show that the absorption spectrum can be split from one peak to two peaks by the control field, and this can also be done by placing the metal sphere close to the quantum dot. When the two are extremely close together, a self-interaction in the quantum dot produces an asymmetry in the absorption peaks. In addition, the fluorescence efficiency can be quenched by the addition of a metal nanosphere. This hybrid system could be used to create ultra-fast switching and sensing nanodevices.

  20. Fabrication and optimization of light emitting devices with core-shell quantum dots

    E-Print Network [OSTI]

    Song, Katherine Wei

    2013-01-01T23:59:59.000Z

    Quantum dot light emitting devices (QD-LEDs) are promising options for the next generation of solid state lighting, color displays, and other optoelectronic applications. Overcoating quantum dots (QDs) -- semiconducting ...

  1. Low-Cost Photovoltaics: Luminescent Solar Concentrators And Colloidal Quantum Dot Solar Cells

    E-Print Network [OSTI]

    Leow, Shin Woei

    2014-01-01T23:59:59.000Z

    enhancing the efficiency of solar cells and extending theirA. J. Nozik, “Quantum dot solar cells,” Phys. E Low-Dimens.oxide PbS quantum dot solar cells at low temperature,” Appl.

  2. An Investigation on Gel Electrophoresis with Quantum Dots End-labeled DNA

    E-Print Network [OSTI]

    Chen, Xiaojia

    2009-05-15T23:59:59.000Z

    explored manipulating DNA fragments by end labeling DNA molecules with quantum dot nanocrystals. The quantum dot-DNA conjugates can be further modified through binding interactions with biotinylated single-stranded DNA primers. Single molecule visualization...

  3. Fluorescent of C-dot composite thin films and its properties

    SciTech Connect (OSTI)

    Mahen, Ea Cahya Septia, E-mail: ferry@fi.itb.ac.id; Nuryadin, Bebeh W., E-mail: ferry@fi.itb.ac.id; Iskandar, Ferry, E-mail: ferry@fi.itb.ac.id; Abdullah, Mikrajuddin, E-mail: ferry@fi.itb.ac.id; Khairurrijal, E-mail: ferry@fi.itb.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung, 40132 (Indonesia)

    2014-02-24T23:59:59.000Z

    In the present work, we report the preparation of a fluorescent carbon nanodots (C-dots) epoxy composite thin films on a glass substrate. C-dots were prepared directly by a simple hydrothermal method using citric acid as a carbon source. The C-dots solutions were mixed with a transparent epoxy resin to form C-dot epoxy composite. Furthermore, the composite precursor was deposited on the glass substrate using a spin coating method in order to fabricate C-dot epoxy composite thin film. The transmittance intensity of C-dot composite film reached up to 90% in the visible light spectra. Using Swanopoel method, the film thickness of fabricated C-dot composite film was determined at about 1.45 ?m, a value lies in a typical range needed for a wide range application. Thus, the C-dot composite film is promising in broadening applications in various fields such as energy conversion, optoelectronics, and display technology.

  4. Postdoctoral Positions: Si/SiGe Quantum Dots and Quantum Computing Eriksson Group

    E-Print Network [OSTI]

    Saffman, Mark

    Postdoctoral Positions: Si/SiGe Quantum Dots and Quantum Computing Eriksson Group Department in the area of Si/SiGe quantum dots and quantum computing. Recent advances in our group include single

  5. Manipulating surface diffusion and elastic interactions to obtain quantum dot multilayer arrangements over different length scales

    SciTech Connect (OSTI)

    Placidi, E., E-mail: ernesto.placidi@ism.cnr.it; Arciprete, F. [Istituto di Struttura della Materia, CNR, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Università di Roma “Tor Vergata”, Dipartimento di Fisica, via della Ricerca Scientifica 1, 00133 Rome (Italy); Latini, V.; Latini, S.; Patella, F. [Università di Roma “Tor Vergata”, Dipartimento di Fisica, via della Ricerca Scientifica 1, 00133 Rome (Italy); Magri, R. [Dipartimento di Scienze Fisiche, Informatiche e Matematiche (FIM), Università di Modena e Reggio Emilia, and Centro S3 CNR-Istituto Nanoscienze, Via Campi 213/A, 4100 Modena (Italy); Scuderi, M.; Nicotra, G. [CNR-IMM, Strada VIII, 5, 95121 Catania (Italy)

    2014-09-15T23:59:59.000Z

    An innovative multilayer growth of InAs quantum dots on GaAs(100) is demonstrated to lead to self-aggregation of correlated quantum dot chains over mesoscopic distances. The fundamental idea is that at critical growth conditions is possible to drive the dot nucleation only at precise locations corresponding to the local minima of the Indium chemical potential. Differently from the known dot multilayers, where nucleation of new dots on top of the buried ones is driven by the surface strain originating from the dots below, here the spatial correlations and nucleation of additional dots are mostly dictated by a self-engineering of the surface occurring during the growth, close to the critical conditions for dot formation under the fixed oblique direction of the incoming As flux, that drives the In surface diffusion.

  6. FISH and Chips: Automation of Fluorescent Dot Counting in Interphase Cell Nuclei

    E-Print Network [OSTI]

    van Vliet, Lucas J.

    ) in each cell nucleus. This system works with two fluorescent dyes, one for the DNA hybridization dotsFISH and Chips: Automation of Fluorescent Dot Counting in Interphase Cell Nuclei Hans Netten,1 Ian abnormalities in inter- phase cell nuclei. This process is called dot counting. To estimate the distribution

  7. Self-organized formation of quantum dots of a material on a substrate

    DOE Patents [OSTI]

    Zhang, Zhenyu (232 Long Bow Rd., Knoxville, TN 37922); Wendelken, John F. (925 Suwanee Rd., Knoxville, TN 37923); Chang, Ming-Che (F4-2, No. 178 Sec 5 Minsheng East Rd., Taipei, TW); Pai, Woei Wu (1F, No. 17, Alley 11, Lane 202, Ming Chyuan Rd., Pan Chou City, Taipei County, TW)

    2001-01-01T23:59:59.000Z

    Systems and methods are described for fabricating arrays of quantum dots. A method for making a quantum dot device, includes: forming clusters of atoms on a substrate; and charging the clusters of atoms such that the clusters of atoms repel one another. The systems and methods provide advantages because the quantum dots can be ordered with regard to spacing and/or size.

  8. A highly efficient (>6%) Cd1xMnxSe quantum dot sensitized solar cell

    E-Print Network [OSTI]

    Cao, Guozhong

    A highly efficient (>6%) Cd1ÀxMnxSe quantum dot sensitized solar cell Jianjun Tian,*a Lili Lv,a Chengbin Fei,b Yajie Wang,b Xiaoguang Liua and Guozhong Cao*bc Quantum dot sensitized solar cells (QDSCs-effective solar cell. The design and synthesis of quantum dots (QDs) for achieving high photoelectric performance

  9. Properties of GaN and ZnO Quantum Dots

    E-Print Network [OSTI]

    CHAPTER 3 Properties of GaN and ZnO Quantum Dots Vladimir A. Fonoberov, Alexander A. Balandin Nano. GaN Quantum Dots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 2.1. Electron and Hole States in Strained Wurtzite and Zincblende GaN Quantum Dots

  10. Temperature-Tuning of Near-Infrared Monodisperse Quantum Dot Solids at

    E-Print Network [OSTI]

    Hone, James

    include solar energy conversion as well as quantum communication. In quantum dot systems, the dot sizes photovoltaics, capturing the infrared spectrum, and also exhibiting possible multi- exciton generation.4. Incoherent Fo¨rster resonance energy transfer (FRET) 8­11 can occur between different-sized quantum dots

  11. Quantum dots and etch-induced depletion of a silicon two-dimensional electron gas

    E-Print Network [OSTI]

    Coppersmith, Susan N.

    Quantum dots and etch-induced depletion of a silicon two-dimensional electron gas L. J. Klein, K. L coupled quantum dots containing individual electrons whose spins act as qubits.4 We have made recent in a silicon quantum dot can be held constant for up to 11 hours. This fulfills an important milestone towards

  12. DOT-7A Type A packaging design guide

    SciTech Connect (OSTI)

    Kelly, D.L.

    1995-01-23T23:59:59.000Z

    The purpose of this Design Guide is to provide instruction for designing a U.S. Department of Transportation Specification 7A (DOT-7A) Type A packaging. Another purpose for this Design Guide is to support the evaluation and testing activities that are performed on new designs by a U.S. Department of Energy (DOE) test facility. This evaluation and testing program is called the DOT-7A Program. When an applicant has determined that a DOT-7A packaging is needed and not commercially available, a design may be created according to this document. The design should include a packaging drawing, specifications, analysis report, operating instructions, and a Packaging Qualification Checklist; all of which should be forwarded to a DOE/HQ approved test facility for evaluation and testing. This report is being submitted through the Engineering Documentation System so that it may be used for reference and information purposes.

  13. Isotopic and internal CX{sub 3} (X=D,H) rotational motion effects in the Ba{center_dot}{center_dot}{center_dot}FCX{sub 3}+h{nu}{yields}BaF+CX{sub 3} intracluster reactions

    SciTech Connect (OSTI)

    Rinaldi, C. A.; Gasmi, K.; Skowronek, S.; Gonzalez Urena, A. [Unidad de Laseres y Haces Moleculares, Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo Juan XXIII-1, 28040 Madrid (Spain)

    2006-06-28T23:59:59.000Z

    Photodepletion and action spectra of the laser-induced Ba{center_dot}{center_dot}{center_dot}FCD{sub 3} fragmentation have been measured over the 16 075-16 380 cm{sup -1} range. The observed band and peak structures allowed us to estimate the vibrational and rotational structures of the excited complex at the transition state configuration. The relative reaction probability P{sub R}(E) for the intracluster Ba{center_dot}{center_dot}{center_dot}FCD{sub 3}+h{nu}{yields}BaF+CD{sub 3} reaction has been determined over the cited energy range. P{sub R}(E) shows a peak structure with an energy spacing of 8.9 cm{sup -1} which was attributed to an internal rotation of the CD{sub 3} group in the intermediate state. A comparison with previous Ba{center_dot}{center_dot}{center_dot}FCH{sub 3} photofragmentation spectra reveals the dynamical role of the internal CX{sub 3} (X=H,D) motion which is manifested by the presence of rotational resonances in the laser-induced intracluster reaction.

  14. Electrically-protected resonant exchange qubits in triple quantum dots

    E-Print Network [OSTI]

    J. M. Taylor; V. Srinivasa; J. Medford

    2013-04-12T23:59:59.000Z

    We present a modulated microwave approach for quantum computing with qubits comprising three spins in a triple quantum dot. This approach includes single- and two-qubit gates that are protected against low-frequency electrical noise, due to an operating point with a narrowband response to high frequency electric fields. Furthermore, existing double quantum dot advances, including robust preparation and measurement via spin-to-charge conversion, are immediately applicable to the new qubit. Finally, the electric dipole terms implicit in the high frequency coupling enable strong coupling with superconducting microwave resonators, leading to more robust two-qubit gates.

  15. DOT-7A Type A packaging test and evaluation procedure

    SciTech Connect (OSTI)

    Kelly, D.L., Westinghouse Hanford

    1996-06-13T23:59:59.000Z

    The purpose of this document is to provide guidance for qualifying a DOT-7A Type A packaging for use. WHC qualifies DOT-7A packaging for two purposes. The first is to provide packages for use by WHC (manufacturer-qualified). The second is to provide a contracted service in support of DOE/EM-76 (DOE-qualified). This document includes descriptions of the performance tests, the personnel involved and their qualifications, appropriate safety and quality assurance considerations, and the procedures to be followed when WHC performs the tests (either as the manufacturer, or on behalf of the DOE`s certification program).

  16. Cooling an electron gas using quantum dot based electronic refrigeration

    E-Print Network [OSTI]

    Prance, Jonathan Robert

    2009-10-13T23:59:59.000Z

    Cooling an electron gas using quantum dot based electronic refrigeration Jonathan Robert Prance August 28, 2009 Downing College, University of Cambridge A thesis submitted for the degree of Doctor of Philosophy Preface The work presented... dots. Conventionally, low temperature measurements of 2DEGs are made by cooling the sample to 1.5 K with liquid Helium-4, to 300 mK with liquid Helium-3, or even down to a few mK using a dilution refrigerator. However, at lower temperatures the electron...

  17. Simulations of the spontaneous emission of a quantum dot near a gap plasmon waveguide

    SciTech Connect (OSTI)

    Perera, Chamanei S., E-mail: cp.hettiarachchige@qut.edu.au; Vernon, Kristy C.; Mcleod, Angus [Plasmonic Device Group, Queensland University of Technology, GPO box 2434, Brisbane, Queensland (Australia)

    2014-02-07T23:59:59.000Z

    In this paper, we modeled a quantum dot at near proximity to a gap plasmon waveguide to study the quantum dot-plasmon interactions. Assuming that the waveguide is single mode, this paper is concerned about the dependence of spontaneous emission rate of the quantum dot on waveguide dimensions such as width and height. We compare coupling efficiency of a gap waveguide with symmetric configuration and asymmetric configuration illustrating that symmetric waveguide has a better coupling efficiency to the quantum dot. We also demonstrate that optimally placed quantum dot near a symmetric waveguide with 50?nm?×?50?nm cross section can capture 80% of the spontaneous emission into a guided plasmon mode.

  18. Intermediate-band photosensitive device with quantum dots having tunneling barrier embedded in organic matrix

    DOE Patents [OSTI]

    Forrest, Stephen R. (Ann Arbor, MI)

    2008-08-19T23:59:59.000Z

    A plurality of quantum dots each have a shell. The quantum dots are embedded in an organic matrix. At least the quantum dots and the organic matrix are photoconductive semiconductors. The shell of each quantum dot is arranged as a tunneling barrier to require a charge carrier (an electron or a hole) at a base of the tunneling barrier in the organic matrix to perform quantum mechanical tunneling to reach the respective quantum dot. A first quantum state in each quantum dot is between a lowest unoccupied molecular orbital (LUMO) and a highest occupied molecular orbital (HOMO) of the organic matrix. Wave functions of the first quantum state of the plurality of quantum dots may overlap to form an intermediate band.

  19. Farewell to a water resources legend: B.L. Harris retires after more than 10 years with the Texas Water Resources Institute

    E-Print Network [OSTI]

    Kalisek, Danielle

    2011-01-01T23:59:59.000Z

    on this legacy. Bill has made an exceptional impact on TWRI and the water programs in Texas and the United States.? From developing state and federal initiatives to providing input on strategic planning, Harris has positioned priority water issues within..., TWRI developed and submi#14;ed #27;#21;#26; individual proposals for water projects, most with TWRI as lead and some that TWRI facilitated. Of those submi#14;ed proposals, #25;#27;#25; were funded, amounting to #22;#21;#21; million. In conjunction...

  20. Photon-Assisted Tunneling in a Carbon Nanotube Quantum Dot

    E-Print Network [OSTI]

    not use highly doped Si to avoid leakage of the high- frequency signal to the back gate. The quantum dot is formed between aluminum source/drain contacts, and the potential can be tuned using an aluminum side to source and drain contacts. To transport the microwave signal to the device, we use semirigid coaxial

  1. Portland Cement Concrete Pavement Shannon Golden, Alabama DOT

    E-Print Network [OSTI]

    Portland Cement Concrete Pavement Shannon Golden, Alabama DOT PORTLAND CEMENT CONCRETE PAVEMENT may be substituted for part of the required Portland cement. Substitution of mineral admixtures shall Cement shall not exceed the percentages shown in the following table: MAXIMUM ALLOWABLE SUBSTITUTION

  2. TRICOLOR LIGHT EMITTING DIODE DOT MATRIX DISPLAY SYSTEM WITHAUDIO OUTPUT

    E-Print Network [OSTI]

    Pang, Grantham

    1 TRICOLOR LIGHT EMITTING DIODE DOT MATRIX DISPLAY SYSTEM WITHAUDIO OUTPUT Grantham Pang, Chi emitting diodes; tricolor display; audio communication. I. Introduction This paper relates to a tricolor broadcasting through the visible light rays transmitted by the display panel or assembly. Keywords: light

  3. Alabama DOT: Alabama Report Questions on NDT Testing

    E-Print Network [OSTI]

    Alabama DOT: Alabama Report Questions on NDT Testing 1. What NDT testing methods for concrete materials, concrete pavements, and overlays are you trying? · We perform pavement smoothness testing, pavement friction testing and FWD testing · We are currently using GPR on the I-59 project to locate voids

  4. State DOT: California State Report Questions on NDT Testing

    E-Print Network [OSTI]

    test for this purpose. For concrete pavement, California has used falling weight deflectometer (FWD locations within concrete pavement. 2. In your experience, how does the reliability of NDT testing methodsState DOT: California State Report Questions on NDT Testing 1. What NDT testing methods

  5. State DOT: Louisiana State Report Questions on NDT Testing

    E-Print Network [OSTI]

    State DOT: Louisiana State Report Questions on NDT Testing 1. What NDT testing methods for concrete materials, concrete pavements, and overlays are you trying? LADOTD does not test concrete pavements or overlays non-destructively. We do use the surface resistivity meter for non-destructive testing

  6. Nonclassical Radiation from a Single Quantum Dot P. Michler1

    E-Print Network [OSTI]

    Buratto, Steve

    Nonclassical Radiation from a Single Quantum Dot P. Michler1 ) (a, b), A. Imamoglu (a), A. Kiraz (a nature of radiation and provides direct evi- dence that the emission source is a single two-level quantum of a single atom in an atomic beam [1] and from a single ion which has been stored in a radiofrequency trap [2

  7. Quantum Dot-Aptamer Conjugates for Synchronous Cancer Imaging, Therapy,

    E-Print Network [OSTI]

    Zhang, Liangfang

    a novel quantum dot (QD)-aptamer(Apt)-doxorubicin (Dox) conjugate [QD-Apt(Dox)] as a targeted cancer of prostate cancer cells that express the PSMA protein. The intercalation of Dox, a widely used antineoplastic in a targeted QD-Apt(Dox) conjugate with reversible self- quenching properties based on a Bi-FRET mechanism

  8. Wisconsin DOT 1. Briefly summarize your current pavement smoothness requirements.

    E-Print Network [OSTI]

    Wisconsin DOT 1. Briefly summarize your current pavement smoothness requirements. We currently-contact profiling equipment. Most PCC pavements are profiled using lightweight profilers when the project is still closed to traffic. Most HMA pavements are profiled using high speed profilers (with the same measuring

  9. California DOT 1. Briefly summarize your current pavement smoothness requirements.

    E-Print Network [OSTI]

    California DOT 1. Briefly summarize your current pavement smoothness requirements. For HMA pavement to OGFC placed on existing pavement not constructed under the same project. If concrete pavement is placed ordered. 39-1.12B Straightedge The top layer of HMA pavement must not vary from the lower edge of a12-foot

  10. Quantum dot-based nanomaterials for biological imaging

    E-Print Network [OSTI]

    Zimmer, John P. (John Philip)

    2006-01-01T23:59:59.000Z

    Quantum dot-based fluorescent probes were synthesized and applied to biological imaging in two distinct size regimes: (1) 100-1000 nm and (2) < 10 nm in diameter. The larger diameter range was accessed by doping CdSe/ZnS ...

  11. Supplementary Document CdSe quantum dot synthesis

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    , TOP (Sigma Aldrich) have been used as pure as supplied from the companies without further purification solar cell The reflection measurements have been carried out for the nanopillar solar cells before that the reflection of Si nanopillar solar cells drops off with the integration of quantum dots by 9-14%, which shows

  12. Mn/DOT's Ombudsman Program Collaboration and Process

    E-Print Network [OSTI]

    Minnesota, University of

    Mn/DOT's Ombudsman Program Collaboration and Process #12;Overview Ombudsman exists to rebuild trust on the environmental and municipal consent processes can be critical #12;A Large Organization #12;Tragedy;Ombudsman Does Not... ·! Advocate for one party or point of view ·! Own any formal process or policy

  13. Simulation of quantum dots size and spacing effect for intermediate band solar cell application based on InAs quantum dots arrangement in GaAs

    SciTech Connect (OSTI)

    Hendra, P. I. B., E-mail: ib.hendra@gmail.com; Rahayu, F., E-mail: ib.hendra@gmail.com; Darma, Y., E-mail: ib.hendra@gmail.com [Physical Vapor Deposition Laboratory, Physics of Material Electronics Research, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2014-03-24T23:59:59.000Z

    Intermediate band solar cell (IBSC) has become a promising technology in increasing solar cell efficiency. In this work we compare absorption coefficient profile between InAs quantum dots with GaAs bulk. We calculate the efficiency of GaAs bulk and GaAs doped with 2, 5, and 10 nm InAs quantum dot. Effective distances in quantum dot arrangement based on electron tunneling consideration were also calculated. We presented a simple calculation method with low computing power demand. Results showed that arrangement of quantum dot InAs in GaAs can increase solar cell efficiency from 23.9 % initially up to 60.4%. The effective distance between two quantum dots was found 2 nm in order to give adequate distance to prevent electron tunneling and wave functions overlap.

  14. Ordered quantum dot molecules and single quantum dots formed by self-organized anisotropic strain engineering

    SciTech Connect (OSTI)

    Lippen, T. van; Noetzel, R.; Hamhuis, G.J.; Wolter, J.H. [European Institute of Telecommunication Technologies/Communication Technology, Basic Research and Applications (eiTT/COBRA) Inter-University Research Institute, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)

    2005-02-15T23:59:59.000Z

    An ordered lattice of lateral InAs quantum dot (QD) molecules is created by self-organized anisotropic strain engineering of an (In,Ga)As/GaAs superlattice (SL) template on GaAs(311)B by molecular-beam epitaxy, constituting a Turing pattern in solid state. The SL template and InAs QD growth conditions, such as the number of SL periods, growth temperatures, amount and composition of deposited (In,Ga)As, and insertion of Al-containing layers, are studied in detail for an optimized QD ordering within and among the InAs QD molecules on the SL template nodes, which is evaluated by atomic force microscopy. The average number of InAs QDs within the molecules is controlled by the thickness of the upper GaAs separation layer on the SL template and the (In,Ga)As growth temperature in the SL. The strain-correlated growth in SL template formation and QD ordering is directly confirmed by high-resolution x-ray diffraction. Ordered arrays of single InAs QDs on the SL template nodes are realized for elevated SL template and InAs QD growth temperatures together with the insertion of a second InAs QD layer. The InAs QD molecules exhibit strong photoluminescence (PL) emission up to room temperature. Temperature-dependent PL measurements exhibit an unusual behavior of the full width at half maximum, indicating carrier redistribution solely within the QD molecules.

  15. Impact of nanostructure configuration on the photovoltaic performance of quantum dot arrays

    E-Print Network [OSTI]

    Berbezier, Aude

    2014-01-01T23:59:59.000Z

    In this work, an effective quantum model based on the non-equilibrium Green's function formalism is used to investigate a selectively contacted high density quantum dot array in an wide band gap host matrix for operation as a quantum dot-enhanced single junction solar cell. By establishing a direct relation between nanostructure configuration and optoelectronic properties, the investigation reveals the influence of inter-dot and dot-contact coupling strength on the radiative rates and consequently on the ultimate performance of photovoltaic devices with finite quantum dot arrays as the active medium. The dominant effects originate in the dependence of the Joint Density of States on the inter-dot coupling in terms of band width and effective band gap.

  16. Antimony mediated growth of high-density InAs quantum dots for photovoltaic cells

    SciTech Connect (OSTI)

    Tutu, F. K.; Wu, J.; Lam, P.; Tang, M.; Liu, H. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)] [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Miyashita, N.; Okada, Y. [Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-Ku, Tokyo 153-8904 (Japan)] [Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-Ku, Tokyo 153-8904 (Japan); Wilson, J.; Allison, R. [Defence Science and Technology Laboratory, Portsdown West, Portsdown Hill Road, Fareham Hants PO17 6AD (United Kingdom)] [Defence Science and Technology Laboratory, Portsdown West, Portsdown Hill Road, Fareham Hants PO17 6AD (United Kingdom)

    2013-07-22T23:59:59.000Z

    We report enhanced solar cell performance using high-density InAs quantum dots. The high-density quantum dot was grown by antimony mediated molecular beam epitaxy. In-plane quantum dot density over 1 × 10{sup 11} cm{sup ?2} was achieved by applying a few monolayers of antimony on the GaAs surface prior to quantum dot growth. The formation of defective large clusters was reduced by optimization of the growth temperature and InAs coverage. Comparing with a standard quantum dot solar cell without the incorporation of antimony, the high-density quantum dot solar cell demonstrates a distinct improvement in short-circuit current from 7.4 mA/cm{sup 2} to 8.3 mA/cm{sup 2}.

  17. Entanglement distribution for a practical quantum-dot-based quantum processor architecture

    E-Print Network [OSTI]

    Timothy P. Spiller; Irene D'Amico; Brendon W. Lovett

    2007-04-13T23:59:59.000Z

    We propose a quantum dot architecture for enabling universal quantum information processing. Quantum registers, consisting of arrays of vertically stacked self-assembled semiconductor quantum dots, are connected by chains of in-plane self-assembled dots. We propose an entanglement distributor, a device for producing and distributing maximally entangled qubits on demand, communicated through in-plane dot chains. This enables the transmission of entanglement to spatially separated register stacks, providing a resource for the realisation of a sizeable quantum processor built from coupled register stacks of practical size. Our entanglement distributor could be integrated into many of the present proposals for self-assembled quantum dot-based quantum computation. Our device exploits the properties of simple, relatively short, spin-chains and does not require microcavities. Utilizing the properties of self-assembled quantum dots, after distribution the entanglement can be mapped into relatively long lived spin qubits and purified, providing a flexible, distributed, off-line resource.

  18. A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots

    E-Print Network [OSTI]

    D. M. Zajac; T. M. Hazard; X. Mi; K. Wang; J. R. Petta

    2015-02-05T23:59:59.000Z

    We demonstrate a reconfigurable quantum dot gate architecture that incorporates two interchangeable transport channels. One channel is used to form quantum dots and the other is used for charge sensing. The quantum dot transport channel can support either a single or a double quantum dot. We demonstrate few-electron occupation in a single quantum dot and extract charging energies as large as 6.6 meV. Magnetospectroscopy is used to measure valley splittings in the range of 35-70 microeV. By energizing two additional gates we form a few-electron double quantum dot and demonstrate tunable tunnel coupling at the (1,0) to (0,1) interdot charge transition.

  19. The UniversiTy of ChiCago harris sChool of PubliC PoliCy harrissChool.uChiCago.edu 1 Federal spending.

    E-Print Network [OSTI]

    Butler, Laurie J.

    Cy harrissChool.uChiCago.edu 1 Federal spending. International development. Crime and corruption. Economics: elizabeth Pearson, MPP'10, presents research on u.S. economic development; Cristal thomas, MPP'01, deputy for the public good and backed by research and evidence. At the University of Chicago Irving B. Harris School

  20. Formation of long-range ordered quantum dots arrays in amorphous matrix by ion beam irradiation

    SciTech Connect (OSTI)

    Buljan, M. [Charles University in Prague, Prague 12116 (Czech Republic); Ruder Boskovic Institute, Zagreb 10000 (Croatia); Bogdanovic-Radovic, I.; Karlusic, M.; Desnica, U. V.; Radic, N.; Dubcek, P. [Ruder Boskovic Institute, Zagreb 10000 (Croatia); Drazic, G. [Jozef Stefan Institute, Ljubljana 1000 (Slovenia); Salamon, K. [Institute of Physics, Zagreb 10000 (Croatia); Bernstorff, S. [Sincrotrone Trieste, Basovizza 34012 (Italy); Holy, V. [Charles University in Prague, Prague 12116 (Czech Republic)

    2009-08-10T23:59:59.000Z

    We demonstrate the production of a well ordered three-dimensional array of Ge quantum dots in amorphous silica matrix. The ordering is achieved by ion beam irradiation and annealing of a multilayer film. Structural analysis shows that quantum dots nucleate along the direction of the ion beam used for irradiation, while the mutual distance of the quantum dots is determined by the diffusion properties of the multilayer material rather than the distances between traces of ions that are used for irradiation.

  1. Phonon-mediated coupling between quantum dots through an off-resonant microcavity

    E-Print Network [OSTI]

    Arka Majumdar; Michal Bajcsy; Armand Rundquist; Erik Kim; Jelena Vuckovic

    2011-11-30T23:59:59.000Z

    We present experimental results showing phonon-mediated coupling between two quantum dots embedded inside a photonic crystal microcavity. With only one of the dots being spectrally close to the cavity, we observe both frequency up-conversion and down-conversion of the pump light via a $\\sim1.2$ THz phonon. We demonstrate this process for both weak and strong regimes of dot-cavity coupling, and provide a simple theoretical model explaining our observations.

  2. Quantum optics and cavity QED with quantum dots in photonic crystals

    E-Print Network [OSTI]

    Jelena Vuckovic

    2014-02-11T23:59:59.000Z

    This chapter will primarily focus on the studies of quantum optics with semiconductor, epitaxially grown quantum dots embedded in photonic crystal cavities. We will start by giving brief introductions into photonic crystals and quantum dots, then proceed with the introduction to cavity quantum electrodynamics (QED) effects, with a particular emphasis on the demonstration of these effects on the quantum dot-photonic crystal platform. Finally, we will focus on the applications of such cavity QED effects.

  3. Features of the electronic spectrum in a type-I core - shell quantum dot

    SciTech Connect (OSTI)

    Igoshina, S E; Karmanov, A A [Penza State University, Penza (Russian Federation)

    2013-01-31T23:59:59.000Z

    The model is proposed, which allows one to solve the problem of finding the energy spectrum and the wave function of an electron in a type-I core - shell quantum dot. It is shown that the size of the core and shell can serve as control parameters for the optimisation of the energy structure of the quantum dot in order to obtain the real structures with desired electrophysical and optical properties. (quantum dots)

  4. Whispering gallery modes in quantum dot-embedded dielectric microspheres for tagless remote refractometric sensing

    E-Print Network [OSTI]

    Pang, Shuo

    2008-10-10T23:59:59.000Z

    S coating. The CdSe/Zns core/shell quantum dots are prepared colloidally via organometallic synthesis. In these experiments, green quantum dots with an emission peak at 530nm are used. The absorption and emission spectra are shown in Figure 9. 23... WHISPERING GALLERY MODES IN QUANTUM DOT-EMBEDDED DIELECTRIC MICROSPHERES FOR TAGLESS REMOTE REFRACTOMETRIC SENSING A Thesis by SHUO PANG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment...

  5. NREL Certifies First All-Quantum-Dot Photovoltaic Cell; Demonstrates Stability, Performance (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2011-02-01T23:59:59.000Z

    Researchers at the National Renewable Energy Laboratory (NREL) have certified the first all-quantum-dot photovoltaic cell, which was based on lead sulfide and demonstrated reasonable quantum dot solar cell performance for an initial efficiency measurement along with good stability. The certified open-circuit voltage of the quantum dot cell is greater than that possible from bulk lead sulfide because of quantum confinement.

  6. Single-electron shuttle based on a silicon quantum dot

    E-Print Network [OSTI]

    K. W. Chan; M. Mottonen; A. Kemppinen; N. S. Lai; K. Y. Tan; W. H. Lim; A. S. Dzurak

    2011-10-05T23:59:59.000Z

    We report on single-electron shuttling experiments with a silicon metal-oxide-semiconductor quantum dot at 300 mK. Our system consists of an accumulated electron layer at the Si/SiO_2 interface below an aluminum top gate with two additional barrier gates used to deplete the electron gas locally and to define a quantum dot. Directional single-electron shuttling from the source and to the drain lead is achieved by applying a dc source-drain bias while driving the barrier gates with an ac voltage of frequency f_p. Current plateaus at integer levels of ef_p are observed up to f_p = 240 MHz operation frequencies. The observed results are explained by a sequential tunneling model which suggests that the electron gas may be heated substantially by the ac driving voltage.

  7. Resonant scattering of surface plasmon polaritons by dressed quantum dots

    SciTech Connect (OSTI)

    Huang, Danhong; Cardimona, Dave [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Easter, Michelle [Department of Mechanical Engineering, Stevens Institute of Technology, 1 Castle Point Terrace, Hoboken, New Jersey 07030 (United States); Gumbs, Godfrey [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Maradudin, A. A. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Lin, Shawn-Yu [Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Zhang, Xiang [Department of Mechanical Engineering, 3112 Etcheverry Hall, University of California at Berkeley, Berkeley, California 94720 (United States)

    2014-06-23T23:59:59.000Z

    The resonant scattering of surface plasmon-polariton waves (SPP) by embedded semiconductor quantum dots above the dielectric/metal interface is explored in the strong-coupling regime. In contrast to non-resonant scattering by a localized dielectric surface defect, a strong resonant peak in the spectrum of the scattered field is predicted that is accompanied by two side valleys. The peak height depends nonlinearly on the amplitude of SPP waves, reflecting the feedback dynamics from a photon-dressed electron-hole plasma inside the quantum dots. This unique behavior in the scattered field peak strength is correlated with the occurrence of a resonant dip in the absorption spectrum of SPP waves due to the interband photon-dressing effect. Our result on the scattering of SPP waves may be experimentally observable and applied to spatially selective illumination and imaging of individual molecules.

  8. Computational models for the berry phase in semiconductor quantum dots

    SciTech Connect (OSTI)

    Prabhakar, S., E-mail: rmelnik@wlu.ca; Melnik, R. V. N., E-mail: rmelnik@wlu.ca [M2NeT Lab, Wilfrid Laurier University, 75 University Ave W, Waterloo, ON N2L 3C5 (Canada); Sebetci, A. [Department of Mechanical Engineering, Mevlana University, 42003, Konya (Turkey)

    2014-10-06T23:59:59.000Z

    By developing a new model and its finite element implementation, we analyze the Berry phase low-dimensional semiconductor nanostructures, focusing on quantum dots (QDs). In particular, we solve the Schrödinger equation and investigate the evolution of the spin dynamics during the adiabatic transport of the QDs in the 2D plane along circular trajectory. Based on this study, we reveal that the Berry phase is highly sensitive to the Rashba and Dresselhaus spin-orbit lengths.

  9. Overview of DOE ? DOT December 2009 CNG and Hydrogen Fuels Workshop

    Broader source: Energy.gov (indexed) [DOE]

    (Ambrish Mishra, Oil Industry Safety Directorate, Ministry of Petroleum and Natural Gas) China (Jinyang Zheng, Zhejiang University) United States (Barbara Hennessey, DOT...

  10. Photoconductivity of Si/Ge multilayer structures with Ge quantum dots pseudomorphic to the Si matrix

    SciTech Connect (OSTI)

    Talochkin, A. B., E-mail: tal@thermo.isp.nsc.ru; Chistokhin, I. B. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2011-07-15T23:59:59.000Z

    Longitudinal photoconductivity spectra of Si/Ge multilayer structures with Ge quantum dots grown pseudomorphically to the Si matrix are studied. Lines of optical transitions between hole levels of quantum dots and Si electronic states are observed. This allowed us to construct a detailed energy-level diagram of electron-hole levels of the structure. It is shown that hole levels of pseudomorphic Ge quantum dots are well described by the simplest 'quantum box' model using actual sizes of Ge islands. The possibility of controlling the position of the long-wavelength photosensitivity edge by varying the growth parameters of Si/Ge structures with Ge quantum dots is determined.

  11. artificial quantum-dot helium: Topics by E-print Network

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

    Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells Biology and Medicine Websites Summary: to Third-Generation...

  12. acid-capped cdse quantum-dot: Topics by E-print Network

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

    Quantum Dot Arrays and Applications of Multiple Exciton Generation to Third-Generation Photovoltaic Solar Cells Biology and Medicine Websites Summary: to Third-Generation...

  13. Comment on "Analysis of quantum coherent semiconductor quantum dot p-i-n junction photovoltaic cells"

    E-Print Network [OSTI]

    Scully, Marlan O

    2010-01-01T23:59:59.000Z

    This is a comment on PRL paper by A.P. Kirk "Analysis of quantum coherent semiconductor quantum dot p-i-n junction photovoltaic cells"

  14. A Graphene Quantum Dot with a Single Electron Transistor as Integrated Charge Sensor

    E-Print Network [OSTI]

    Ling-Jun Wang; Gang Cao; Tao Tu; Hai-Ou Li; Cheng Zhou; Xiao-Jie Hao; Zhan Su; Guang-Can Guo; Guo-Ping Guo; Hong-Wen Jiang

    2010-08-28T23:59:59.000Z

    We have developed an etching process to fabricate a quantum dot and a nearby single electron transistor as a charge detector in a single layer graphene. The high charge sensitivity of the detector is used to probe Coulomb diamonds as well as excited spectrum in the dot, even in the regime where the current through the quantum dot is too small to be measured by conventional transport means. The graphene based quantum dot and integrated charge sensor serve as an essential building block to form a solid-state qubit in a nuclear-spin-free quantum world.

  15. Photovoltaic performance of ultra-small PbSe quantum dots

    E-Print Network [OSTI]

    Ma, Wanli

    2014-01-01T23:59:59.000Z

    Y; Alivisatos, AP, Photovoltaic Devices Employing TernaryPhotovoltaic performance of ultra-small PbSe quantum dotsquantum dot, solar cell, photovoltaic, quantum size effect

  16. Size and spatial homogeneity of SiGe quantum dots in amorphous silica matrix

    SciTech Connect (OSTI)

    Buljan, Maja [Faculty of Mathematics and Physics, Charles University in Prague, Prague 12116 (Czech Republic); Ruder Boskovic Institute, P.O. Box 180, 10002 Zagreb (Croatia); Pinto, Sara R. C.; Rolo, Anabela G.; Levichev, Sergey; Gomes, Maria J. M. [Physics Department, University of Minho, 4710-057 Braga (Portugal); Kashtiban, Reza J.; Bangert, Ursel [Nanostructured Materials Research Group, School of Materials, University of Manchester, P.O. Box 88, Manchester, M1 7HS (United Kingdom); Chahboun, Adil [Physics Department, University of Minho, 4710-057 Braga (Portugal); Department of Physics, Dhar Mehraz Sciences Faculty, BP 1796, Fes (Morocco); Holy, Vaclav [Faculty of Mathematics and Physics, Charles University in Prague, Prague 12116 (Czech Republic)

    2009-10-15T23:59:59.000Z

    In this paper, we present a study of structural properties of SiGe quantum dots formed in amorphous silica matrix by magnetron sputtering technique. We investigate deposition conditions leading to the formation of dense and uniformly sized quantum dots, distributed homogeneously in the matrix. X-ray and Raman spectroscopy were used to estimate the Si content. A detailed analysis based on grazing incidence small angle x-ray scattering revealed the influence of the deposition conditions on quantum dot sizes, size distributions, spatial arrangement, and concentration of quantum dots in the matrix, as well as the Si:Ge content.

  17. Biexciton recombination rates in self-assembled quantum dots Michael Wimmer,1, 2,

    E-Print Network [OSTI]

    Shumway, John

    GaAs/GaAs, CdSe/ZnSe, and InP/InGaP dots are evaluated, including anisotropic effective masses. Depending

  18. Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Quantum Dots

    SciTech Connect (OSTI)

    Klimov, V.; McBranch, D.; Schwarz, C.

    1998-08-10T23:59:59.000Z

    Low-dimensional semiconductors have attracted great interest due to the potential for tailoring their linear and nonlinear optical properties over a wide-range. Semiconductor nanocrystals (NC's) represent a class of quasi-zero-dimensional objects or quantum dots. Due to quantum cordhement and a large surface-to-volume ratio, the linear and nonlinear optical properties, and the carrier dynamics in NC's are significantly different horn those in bulk materials. napping at surface states can lead to a fast depopulation of quantized states, accompanied by charge separation and generation of local fields which significantly modifies the nonlinear optical response in NC's. 3D carrier confinement also has a drastic effect on the energy relaxation dynamics. In strongly confined NC's, the energy-level spacing can greatly exceed typical phonon energies. This has been expected to significantly inhibit phonon-related mechanisms for energy losses, an effect referred to as a phonon bottleneck. It has been suggested recently that the phonon bottleneck in 3D-confined systems can be removed due to enhanced role of Auger-type interactions. In this paper we report femtosecond (fs) studies of ultrafast optical nonlinearities, and energy relaxation and trap ping dynamics in three types of quantum-dot systems: semiconductor NC/glass composites made by high temperature precipitation, ion-implanted NC's, and colloidal NC'S. Comparison of ultrafast data for different samples allows us to separate effects being intrinsic to quantum dots from those related to lattice imperfections and interface properties.

  19. Sandia Energy - Harry Atwater

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

    devices for solar fuel production. He is a early pioneer in surface plasmon photonics; he gave the name to the field of plasmonics in 2001; developments in this...

  20. Utah_k_harris

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsing Maps to Predict SolarJohn Keeler, Manti Site -

  1. Dear Mr. Harris,

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny:Revised Finding of No53197 This workDayton: ENERGY8 Deaerators inOctober

  2. TO : W. B. Harris

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7 AugustAFRICAN3uj: ;;I : T' j-jE:, , - :./:'

  3. The solubility of selenate-AFt (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSeO{sub 4}{center_dot}37.5H{sub 2}O) and selenate-AFm (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaSeO{sub 4}{center_dot}xH{sub 2}O)

    SciTech Connect (OSTI)

    Baur, Isabel; Johnson, C. Annette

    2003-11-01T23:59:59.000Z

    The Se(VI)-analogues of ettringite and monosulfate, selenate-AFt (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSeO{sub 4}{center_dot}37.5H{sub 2}O), and selenate-AFm (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaSeO{sub 4}{center_dot}xH{sub 2}O) were synthesised and characterised by bulk chemical analysis and X-ray diffraction. Their solubility products were determined from a series of batch and resuspension experiments conducted at 25 deg. C. For selenate-AFt suspensions, the pH varied between 11.37 and 11.61, and a solubility product, log K{sub so}=61.29{+-}0.60 (I=0 M), was determined for the reaction 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSeO{sub 4}{center_dot}37.5H{sub 2}O+12 H{sup +} implies 6Ca{sup 2+}+2Al{sup 3+}+3SeO{sub 4}{sup 2-}+43.5H{sub 2}O. Selenate-AFm synthesis resulted in the uptake of Na, which was leached during equilibration and resuspension. For the pH range of 11.75 to 11.90, a solubility product, log K{sub so}=73.40{+-}0.22 (I=0 M), was determined for the reaction 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaSeO{sub 4}{center_dot}xH{sub 2}O+12 H{sup +} implies 4Ca{sup 2+}+2Al{sup 3+}+SeO{sub 4}{sup 2-}+(x+6)H{sub 2}O. Thermodynamic modelling suggested that both selenate-AFt and selenate-AFm are stable in the cementitious matrix; and that in a cement limited in sulfate, selenate concentration may be limited by selenate-AFm to below the millimolar range above pH 12.

  4. Coupled electromechanical effects in wurtzite quantum dots with wetting layers in gate controlled electric fields: The multiband case

    E-Print Network [OSTI]

    Melnik, Roderick

    Coupled electromechanical effects in wurtzite quantum dots with wetting layers in gate controlled quantifies the electromechanical effects on the band structure of wurtzite quantum dots. c Systematic study on the band structure calculations of wurtzite AlN/GaN quantum dots with wetting layers (WLs). Based

  5. Water-soluble luminescent quantum dots and biomolecular conjugates thereof and related compositions and method of use

    DOE Patents [OSTI]

    Nie, Shuming (Bloomington, IN); Chan, Warren C. W. (Bloomington, IN); Emory, Steven R. (Los Alamos, NM)

    2002-01-01T23:59:59.000Z

    The present invention provides a water-soluble luminescent quantum dot, a biomolecular conjugate thereof and a composition comprising such a quantum dot or conjugate. Additionally, the present invention provides a method of obtaining a luminescent quantum dot, a method of making a biomolecular conjugate thereof, and methods of using a biomolecular conjugate for ultrasensitive nonisotopic detection in vitro and in vivo.

  6. Water-soluble luminescent quantum dots and biomolecular conjugates thereof and related compositions and methods of use

    DOE Patents [OSTI]

    Nie, Shuming; Chan, Warren C. W.; Emory, Stephen

    2007-03-20T23:59:59.000Z

    The present invention provides a water-soluble luminescent quantum dot, a biomolecular conjugate thereof and a composition comprising such a quantum dot or conjugate. Additionally, the present invention provides a method of obtaining a luminescent quantum dot, a method of making a biomolecular conjugate thereof, and methods of using a biomolecular conjugate for ultrasensitive nonisotopic detection in vitro and in vivo.

  7. Title: Development of Plasmon Assisted Quantum DOT Sensors Multispectral and Polarization Selective Imaging

    E-Print Network [OSTI]

    Johnson, Eric E.

    Title: Development of Plasmon Assisted Quantum DOT Sensors for Multispectral and Polarization in plasmonic nanostructures. Spectral and polarization sensitive EO sensors provide unique remote sensing of subwavelength plasmon-polariton assisted quantum dot (QD) photodetectors (PDs) for pixel-level spectral

  8. Mid Infrared Focal Plane Arrays With Nanoscale Quantum Dots and Superlattices

    E-Print Network [OSTI]

    Krishna, Sanjay

    Mid Infrared Focal Plane Arrays With Nanoscale Quantum Dots and Superlattices S. Krishna Center- Molecular beam epitaxy, Nanoscale, Quantum Dots Superlattices, Antimonides, Mid-infrared photodetector. I. INTRODUCTION Presently, the state of the art photon detectors for the mid wave infrared (MWIR, 3-5 µm) and long

  9. Enlarged symmetry and coherence in arrays of quantum dots A. V. Onufriev and J. B. Marston

    E-Print Network [OSTI]

    Onufriev, Alexey

    . A Hubbard model then describes a pillar array of coupled dots, and at half-filling the system can be mapped materials. Recent advances in nanofabrication tech- niques offer the possibility of constructing artificial- teractions that lift the degeneracy. However, as Stafford and Das Sarma noticed,3 semiconducting quantum dots

  10. Photovoltaic quantum dot quantum cascade infrared photodetector A. V. Barve and S. Krishna

    E-Print Network [OSTI]

    Krishna, Sanjay

    Photovoltaic quantum dot quantum cascade infrared photodetector A. V. Barve and S. Krishna Citation subject to AIP license or copyright; see http://apl.aip.org/about/rights_and_permissions #12;Photovoltaic) Design and characterization of a quantum dot quantum cascade detector for photovoltaic midwave infrared

  11. Bioimaging 4 (1996) 93106. Printed in the UK Fluorescent dot counting in

    E-Print Network [OSTI]

    van Vliet, Lucas J.

    Bioimaging 4 (1996) 93­106. Printed in the UK Fluorescent dot counting in interphase cell nuclei allows the enumeration of chromosomal abnormalities in interphase cell nuclei. This process is called dot counting. To estimate the distribution of chromosomes per cell, a large number of cells have to be analysed

  12. Double-dot charge transport in Si single-electronhole transistors L. P. Rokhinson,a)

    E-Print Network [OSTI]

    Rokhinson, Leonid

    ­oxide­ semiconductor field-effect transistors MOSFETs brought to light several issues related to the electrical beneath the dot transforming it into a free-standing bridge. Subsequently, 40 or 50 nm of oxide are thermally grown which further reduce the size of the dot. Polysilicon gate is deposited over the bridge

  13. Light extraction analysis and enhancement in a quantum dot light emitting diode

    E-Print Network [OSTI]

    Wu, Shin-Tson

    Light extraction analysis and enhancement in a quantum dot light emitting diode Ruidong Zhu outcoupling and angular performance of quantum dot light emitting diode (QLED). To illustrate the design principles, we use a red QLED as an example and compare its performance with an organic light emitting diode

  14. How common are dot-like distributions? Taxonomical oversplitting in western European Agrodiaetus

    E-Print Network [OSTI]

    Pierce, Naomi E.

    How common are dot-like distributions? Taxonomical oversplitting in western European Agrodiaetusbij_1481 130..154 Approximately 50 taxa of butterflies in Western Europe have been described as new, the Balkan Peninsula and Crimea, or to small Mediterranean islands (Kudrna, 2002). Usually, these dot

  15. Are you shipping a DOT Hazardous Material? Is your material listed

    E-Print Network [OSTI]

    Pawlowski, Wojtek

    Are you shipping a DOT Hazardous Material? Is your material listed on the DOT Hazmat Table? http://www.myregs.com/dotrspa/ (select Hazmat Table upper left) Your material is a Hazardous Material and must be shipped following the full regulations. Follow the instructions on the linked page, select the hazard of the material

  16. Minimal Self-Contained Quantum Refrigeration Machine Based on Four Quantum Dots

    E-Print Network [OSTI]

    Davide Venturelli; Rosario Fazio; Vittorio Giovannetti

    2013-06-22T23:59:59.000Z

    We present a theoretical study of an electronic quantum refrigerator based on four quantum dots arranged in a square configuration, in contact with as many thermal reservoirs. We show that the system implements the basic minimal mechanism for acting as a self-contained quantum refrigerator, by demonstrating heat extraction from the coldest reservoir and the cooling of the nearby quantum-dot.

  17. GeSi intermixing in Ge quantum dots on Si,,001... and Si,,111... F. Boscherinia)

    E-Print Network [OSTI]

    Ge­Si intermixing in Ge quantum dots on Si,,001... and Si,,111... F. Boscherinia) Laboratori December 1999 Exploiting Ge K-edge x-ray absorption spectroscopy we provide direct evidence of Si­Ge intermixing in self-organized strained and unstrained Ge quantum dots on Si, and provide a quantitative

  18. Rapid degradation of CdSe/ZnS colloidal quantum dots exposed to gamma irradiation

    E-Print Network [OSTI]

    New Mexico, University of

    Rapid degradation of CdSe/ZnS colloidal quantum dots exposed to gamma irradiation Nathan J. Withers are reported. Optical degradation is evaluated by tracking the dependence of photoluminescence intensity on irradiation dose. CdSe/ZnS quantum dots show poor radiation hardness, and severely degrade after less than 20

  19. Commensurability effects induced by a periodic array of nanoscale anti-dots in Nb superconductor

    E-Print Network [OSTI]

    Metlushko, Vitali

    Commensurability effects induced by a periodic array of nanoscale anti-dots in Nb superconductor A. PACS: 74.25.Ha; 74.76.)w Keywords: Nanostructures; Anti-dots; Commensurability 1. Introduction atomic layers on periodical substrate [5], magnetic bubble arrays [6] and the magnetically induced Wigner

  20. Large open telescope: size-upscaling from DOT to LOT Robert H. Hammerschlaga

    E-Print Network [OSTI]

    Rutten, Rob

    Large open telescope: size-upscaling from DOT to LOT Robert H. Hammerschlaga , Aswin P. L. Jägersb, telescope drives 1. INTRODUCTION The Dutch Open Telescope (DOT) on the Canary island La Palma consists temperature homogeneous. No warm air bubbles are forced upwards against the closed wall of a tower and no heat

  1. Mechanism for thermoelectric figure-of-merit enhancement in regimented quantum dot superlattices

    E-Print Network [OSTI]

    Mechanism for thermoelectric figure-of-merit enhancement in regimented quantum dot superlattices propose a mechanism for enhancement of the thermoelectric figure-of-merit in regimented quantum dot, as a result, to the thermoelectric figure-of-merit enhancement. To maximize the improvement, one has to tune

  2. Evidence for formation of multi-quantum dots in hydrogenated graphene

    E-Print Network [OSTI]

    Chuang, Chiashain; Puddy, Reuben K; Connolly, Malcolm R; Lo, Shun-Tsung; Lin, Huang-De; Chen, Tse-Ming; Smith, Charles G; Liang, Chi-Te

    2012-08-16T23:59:59.000Z

    Abstract We report the experimental evidence for the formation of multi-quantum dots in a hydrogenated single-layer graphene flake. The existence of multi-quantum dots is supported by the low-temperature measurements on a field effect transistor...

  3. Review paper: Toward highly efficient quantum-dot-and dye-sensitized solar cells

    E-Print Network [OSTI]

    Park, Byungwoo

    Review paper: Toward highly efficient quantum-dot- and dye-sensitized solar cells Hongsik Choi Interface control Light harvesting Tandem solar cell a b s t r a c t Dye- and quantum-dot-sensitized solar technologies of silicon-based solar cells should be resolved [7]. Dye-sensitized solar cells (DSSCs) have been

  4. Arrays of nanoscale magnetic dots: Fabrication by x-ray interference lithography and characterization

    SciTech Connect (OSTI)

    Heyderman, L.J.; Solak, H.H.; David, C.; Atkinson, D.; Cowburn, R.P.; Nolting, F. [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Nanomagnetism Group, Department of Physics, University of Durham, Rochester Building, Science Laboratories, South Road, Durham DH1 3LE (United Kingdom); Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2004-11-22T23:59:59.000Z

    X-ray interference lithography (XIL) was employed in combination with electrodeposition to fabricate arrays of nanoscale nickel dots which are uniform over 40 {mu}m and have periods down to 71 nm. Using extreme-ultraviolet light, XIL has the potential to produce magnetic dot arrays over large areas with periods well below 50 nm, and down to a theoretical limit of 6.5 nm for a 13 nm x-ray wavelength. In the nickel dot arrays, we observed the effect of interdot magnetic stray field interactions. Measuring the hysteresis loops using the magneto-optical Kerr effect, a double switching via the vortex state was observed in the nickel dots with diameters down to 44 nm and large dot separations. As the dot separations are reduced to below around 50 nm a single switching, occurring by collective rotation of the magnetic spins, is favored due to interdot magnetic stray field interactions. This results in magnetic flux closure through several dots which could be visualized with micromagnetic simulations. Further evidence of the stray field interactions was seen in photoemission electron microscopy images, where bands of contrast corresponding to chains of coupled dots were observed.

  5. Characterization of a microwave frequency resonator via a nearby quantum dot

    E-Print Network [OSTI]

    Wallraff, Andreas

    and superconducting qubits. The study of the inter- action between the electromagnetic field of such a resonator of a hybrid system consisting of a microwave transmission-line resonator and a lateral quantum dot defined is studied by monitoring the electrical conductance through the quantum dot. The presence of a strong

  6. Ambient-Processed Colloidal Quantum Dot Solar Cells via Individual Pre-Encapsulation of Nanoparticles

    E-Print Network [OSTI]

    Ambient-Processed Colloidal Quantum Dot Solar Cells via Individual Pre-Encapsulation, 2010; E-mail: ted.sargent@utoronto.ca Solution-processed solar cells employing colloidal quantum dots-junction and tandem solar cells both rely on IR-band-gap semiconductors, there has been much recent emphasis

  7. Coupling of PbS Quantum Dots to Photonic Crystal Cavities at Room Temperature

    E-Print Network [OSTI]

    Ilya Fushman; Dirk Englund; Jelena Vuckovic

    2005-05-14T23:59:59.000Z

    We demonstrate the coupling of PbS quantum dot emission to photonic crystal cavities at room temperature. The cavities are defined in 33% Al, AlGaAs membranes on top of oxidized AlAs. Quantum dots were dissolved in Poly-methyl-methacrylate (PMMA) and spun on top of the cavities. Quantum dot emission is shown to map out the structure resonances, and may prove to be viable sources for room temperature cavity coupled single photon generation for quantum information processing applications. These results also indicate that such commercially available quantum dots can be used for passive structure characterization. The deposition technique is versatile and allows layers with different dot densities and emission wavelengths to be re-deposited on the same chip.

  8. Intermediate-band photosensitive device with quantum dots embedded in energy fence barrier

    DOE Patents [OSTI]

    Forrest, Stephen R. (Ann Arbor, MI); Wei, Guodan (Ann Arbor, MI)

    2010-07-06T23:59:59.000Z

    A plurality of layers of a first semiconductor material and a plurality of dots-in-a-fence barriers disposed in a stack between a first electrode and a second electrode. Each dots-in-a-fence barrier consists essentially of a plurality of quantum dots of a second semiconductor material embedded between and in direct contact with two layers of a third semiconductor material. Wave functions of the quantum dots overlap as at least one intermediate band. The layers of the third semiconductor material are arranged as tunneling barriers to require a first electron and/or a first hole in a layer of the first material to perform quantum mechanical tunneling to reach the second material within a respective quantum dot, and to require a second electron and/or a second hole in a layer of the first semiconductor material to perform quantum mechanical tunneling to reach another layer of the first semiconductor material.

  9. Single photon emission from site-controlled InGaN/GaN quantum dots

    SciTech Connect (OSTI)

    Zhang, Lei; Hill, Tyler A.; Deng, Hui, E-mail: dengh@umich.edu [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109 (United States)] [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109 (United States); Teng, Chu-Hsiang; Lee, Leung-Kway; Ku, Pei-Cheng, E-mail: peicheng@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)] [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)

    2013-11-04T23:59:59.000Z

    Single photon emission was observed from site-controlled InGaN/GaN quantum dots. The single-photon nature of the emission was verified by the second-order correlation function up to 90?K, the highest temperature to date for site-controlled quantum dots. Micro-photoluminescence study on individual quantum dots showed linearly polarized single exciton emission with a lifetime of a few nanoseconds. The dimensions of these quantum dots were well controlled to the precision of state-of-the-art fabrication technologies, as reflected in the uniformity of their optical properties. The yield of optically active quantum dots was greater than 90%, among which 13%–25% exhibited single photon emission at 10?K.

  10. Single photon absorption and dynamic control of a coupled quantum dot-cavity system

    E-Print Network [OSTI]

    Robert Johne; Andrea Fiore

    2011-10-11T23:59:59.000Z

    We theoretically investigate the dynamic interaction of a quantum dot in a nanocavity with timesymmetric single photon pulses. The simulations, based on a wavefunction approach, reveal that almost perfect single photon absorption occurs for quantum dot-cavity systems operating on the edge between strong and weak coupling regime. The computed maximum absorptions probability is close to unity for pulses with a typical length comparable to the half of the Rabi period. Furthermore, the dynamic control of the quantum dot energy via electric fields allows the freezing of the light-matter interaction leaving the quantum dot in its excited state. Shaping of single photon wavepackets by the electric field control is limited by the occurrence of chirping of the single photon pulse. This understanding of the interaction of single photon pulses with the quantum dot-cavity system provides the basis for the development of advanced protocols for quantum information processing in the solid state.

  11. A quantum dot implementation of the quantum NAND algorithm

    E-Print Network [OSTI]

    J. M. Taylor

    2007-08-10T23:59:59.000Z

    We propose a physical implementation of the quantum NAND tree evaluation algorithm. Our approach, based on continuous time quantum walks, uses the wave interference of a single electron in a heirarchical set of tunnel coupled quantum dots. We find that the query complexity of the NAND tree evaluation does not suffer strongly from disorder and dephasing, nor is it directly limited by temperature or restricted dimensionality for 2-d structures. Finally, we suggest a potential application of this algorithm to the efficient determination of high-order correlation functions of complex quantum systems.

  12. Computational modeling of electrophotonics nanomaterials: Tunneling in double quantum dots

    SciTech Connect (OSTI)

    Vlahovic, Branislav, E-mail: vlahovic@nccu.edu; Filikhin, Igor, E-mail: vlahovic@nccu.edu [Department of Physics, North Carolina Central University, 1801 Fayetteville Street, Durham, North Carolina 27707 (United States)

    2014-10-06T23:59:59.000Z

    Single electron localization and tunneling in double quantum dots (DQD) and rings (DQR) and in particular the localized-delocalized states and their spectral distributions are considered in dependence on the geometry of the DQDs (DQRs). The effect of violation of symmetry of DQDs geometry on the tunneling is studied in details. The cases of regular and chaotic geometries are considered. It will be shown that a small violation of symmetry drastically affects localization of electron and that anti-crossing of the levels is the mechanism of tunneling between the localized and delocalized states in DQRs.

  13. Photocurrent extraction efficiency in colloidal quantum dot photovoltaics

    SciTech Connect (OSTI)

    Kemp, K. W.; Wong, C. T. O.; Hoogland, S. H.; Sargent, E. H. [Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4 (Canada)] [Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4 (Canada)

    2013-11-18T23:59:59.000Z

    The efficiency of photocurrent extraction was studied directly inside operating Colloidal Quantum Dot (CQD) photovoltaic devices. A model was derived from first principles for a thin film p-n junction with a linearly spatially dependent electric field. Using this model, we were able to clarify the origins of recent improvement in CQD solar cell performance. From current-voltage diode characteristics under 1 sun conditions, we extracted transport lengths ranging from 39 nm to 86 nm for these materials. Characterization of the intensity dependence of photocurrent extraction revealed that the dominant loss mechanism limiting the transport length is trap-mediated recombination.

  14. Photoluminescence-enhanced biocompatible quantum dots by phospholipid functionalization

    SciTech Connect (OSTI)

    Shi Yunfeng [School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); He Peng [Department of Chemistry, North Carolina State University, Raleigh, NC 27695 (United States)], E-mail: phe@ncsu.edu; Zhu Xinyuan [School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Instrumental Analysis Center, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030 (China)], E-mail: xyzhu@sjtu.edu.cn

    2008-10-02T23:59:59.000Z

    A simple two-step strategy using phospholipid (PPL) to functionalize core/shell CdSe/ZnS quantum dots (QDs) has been described. The experimental data show that the use of S-H terminated PPL results not only in the high colloidal stability of core/shell CdSe/ZnS QDs in the aqueous phase, but also in the significant enhancement of photoluminescence. The degree of the enhancement is a function of the PPL-CdSe/ZnS QDs sample concentration. These results might be promising for future biological platform in new devices ranging from photovoltaic cells to biosensors and other devices.

  15. Resonant excitation and photon entanglement from semiconductor quantum dots

    E-Print Network [OSTI]

    Ana Predojevi?

    2015-03-01T23:59:59.000Z

    In this chapter we review the use of semiconductor quantum dots as sources of quantum light. Principally, we focus on resonant two-photon excitation, which is a method that allows for on-demand generation of photon pairs. We explore the advantages of resonant excitation and present a number of measurements that were made in this excitation regime. In particular, we cover the following topics: photon statistics, coherent manipulation of the ground-excited state superposition, and generation of time-bin entangled photon pairs.

  16. Nanoscale engineering boosts performance of quantum dot light emitting

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated CodesTransparency VisitSilver Toyota PriusNSRdiodes Quantum dot light

  17. Activation of molecular catalysts using semiconductor quantum dots

    DOE Patents [OSTI]

    Meyer, Thomas J. (Chapel Hill, NC); Sykora, Milan (Los Alamos, NM); Klimov, Victor I. (Los Alamos, NM)

    2011-10-04T23:59:59.000Z

    Photocatalytic materials based on coupling of semiconductor nanocrystalline quantum dots (NQD) and molecular catalysts. These materials have capability to drive or catalyze non-spontaneous chemical reactions in the presence of visible radiation, ultraviolet radiation, or both. The NQD functions in these materials as a light absorber and charge generator. Following light absorption, the NQD activates a molecular catalyst adsorbed on the surface of the NQD via transfer of one or more charges (either electrons or electron-holes) from the NQD to the molecular catalyst. The activated molecular catalyst can then drive a chemical reaction. A photoelectrolytic device that includes such photocatalytic materials is also described.

  18. Shiny quantum dots brighten future of solar cells

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebookScholarship Fund scholarshipsShedding LightShiny quantum dots

  19. Sandia Energy - InAs Quantum Dot Transitions

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Scienceand RequirementsCoatingsUltra-High-VoltagePower Company'sInAs Quantum Dot Transitions Home

  20. TxDOT - Certification for Utility Accommodation | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro IndustriesTown of Ladoga, IndianaTurtle Airships Jump to:TwiggsJemezwells. (SINDA-3GTxDOT -

  1. Theory of dynamic nuclear polarization and feedback in quantum dots

    E-Print Network [OSTI]

    Sophia E. Economou; Edwin Barnes

    2014-04-06T23:59:59.000Z

    An electron confined in a quantum dot interacts with its local nuclear spin environment through the hyperfine contact interaction. This interaction combined with external control and relaxation or measurement of the electron spin allows for the generation of dynamic nuclear polarization. The quantum nature of the nuclear bath, along with the interplay of coherent external fields and incoherent dynamics in these systems renders a wealth of intriguing phenomena seen in recent experiments such as electron Zeeman frequency focusing, hysteresis, and line dragging. We develop in detail a fully quantum, self-consistent theory that can be applied to such experiments and that moreover has predictive power. Our theory uses the operator sum representation formalism in order to incorporate the incoherent dynamics caused by the additional, Markovian bath, which in self-assembled dots is the vacuum field responsible for electron-hole optical recombination. The beauty of this formalism is that it reduces the complexity of the problem by encoding the joint dynamics of the external coherent and incoherent driving in an effective dynamical map that only acts on the electron spin subspace. This together with the separation of timescales in the problem allows for a tractable and analytically solvable formalism. The key role of entanglement between the electron spin and the nuclear spins in the formation of dynamic nuclear polarization naturally follows from our solution. We demonstrate the theory in detail for an optical pulsed experiment and present an in-depth discussion and physical explanation of our results.

  2. Quantum Dots-based Reverse Phase Protein Microarray

    SciTech Connect (OSTI)

    Shingyoji, Masato; Gerion, Daniele; Pinkel, Dan; Gray, Joe W.; Chen, Fanqing

    2005-07-15T23:59:59.000Z

    CdSe nanocrystals, also called quantum dots (Qdots) are a novel class of fluorophores, which have a diameter of a few nanometers and possess high quantum yield, tunable emission wavelength and photostability. They are an attractive alternative to conventional fluorescent dyes. Quantum dots can be silanized to be soluble in aqueous solution under biological conditions, and thus be used in bio-detection. In this study, we established a novel Qdot-based technology platform that can perform accurate and reproducible quantification of protein concentration in a crude cell lysate background. Protein lysates have been spiked with a target protein, and a dilution series of the cell lysate with a dynamic range of three orders of magnitude has been used for this proof-of-concept study. The dilution series has been spotted in microarray format, and protein detection has been achieved with a sensitivity that is at least comparable to standard commercial assays, which are based on horseradish peroxidase (HRP) catalyzed diaminobenzidine (DAB) chromogenesis. The data obtained through the Qdot method has shown a close linear correlation between relative fluorescence unit and relative protein concentration. The Qdot results are in almost complete agreement with data we obtained with the well-established HRP-DAB colorimetric array (R{sup 2} = 0.986). This suggests that Qdots can be used for protein quantification in microarray format, using the platform presented here.

  3. Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions

    SciTech Connect (OSTI)

    Pinto, S. R. C.; Ramos, M. M. D.; Gomes, M. J. M. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Buljan, M. [Ruder Boskovic Institute, Bijenicka cesta 54, Zagreb 10000 (Croatia); Chahboun, A. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Physics Department, FST Tanger, Tanger BP 416 (Morocco); Roldan, M. A.; Molina, S. I. [Departamento de Ciencia de los Materiales e Ing. Metalurgica y Q. I., Universidad de Cadiz, Cadiz (Spain); Bernstorff, S. [Sincrotrone Trieste, SS 14 km163, 5, Basovizza 34012 (Italy); Varela, M.; Pennycook, S. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Barradas, N. P.; Alves, E. [Instituto Superior Tecnico e Instituto Tecnologico e Nuclear-, EN10, Sacavem 2686-953 (Portugal)

    2012-04-01T23:59:59.000Z

    In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (Ge+SiO{sub 2})/SiO{sub 2} multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (Ge + SiO{sub 2}) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation along the growth direction can be tuned by changing the Ge-rich layer thickness. The average value of the quantum dots size along the lateral (in-plane) direction along with their lateral separation is not affected by the thickness of the Ge-rich layer. However, the thickness of the Ge-rich layer significantly affects the quantum dot ordering. In addition, we investigate the dependence of the multilayer average atomic composition and also the quantum dot crystalline quality on the deposition parameters.

  4. Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions

    SciTech Connect (OSTI)

    Pinto, S. [University of Minho, Portugal; Roldan Gutierrez, Manuel A [ORNL; Ramos, M. M.D. [University of Minho, Portugal; Gomes, M.J.M. [University of Minho, Portugal; Molina, S. I. [Universidad de Cadiz, Spain; Pennycook, Stephen J [ORNL; Varela del Arco, Maria [ORNL; Buljan, M. [R. Boskovic Institute, Zagreb, Croatia; Barradas, N. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Alves, E. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Chahboun, A. [FST Tanger, Morocco; Bernstorff, S. [Sincrotrone Trieste, Basovizza, Italy

    2012-01-01T23:59:59.000Z

    In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (Ge+SiO{sub 2})/SiO{sub 2} multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (Ge + SiO{sub 2}) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation along the growth direction can be tuned by changing the Ge-rich layer thickness. The average value of the quantum dots size along the lateral (in-plane) direction along with their lateral separation is not affected by the thickness of the Ge-rich layer. However, the thickness of the Ge-rich layer significantly affects the quantum dot ordering. In addition, we investigate the dependence of the multilayer average atomic composition and also the quantum dot crystalline quality on the deposition parameters.

  5. Green synthesis of highly efficient CdSe quantum dots for quantum-dots-sensitized solar cells

    SciTech Connect (OSTI)

    Gao, Bing; Shen, Chao; Zhang, Mengya; Yuan, Shuanglong; Yang, Yunxia, E-mail: yangyunxia@ecust.edu.cn, E-mail: grchen@ecust.edu.cn; Chen, Guorong, E-mail: yangyunxia@ecust.edu.cn, E-mail: grchen@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Bo [Department of Physics, East China University of Science and Technology, Shanghai 200237 (China)

    2014-05-21T23:59:59.000Z

    Green synthesis of CdSe quantum dots for application in the quantum-dots-sensitized solar cells (QDSCs) is investigated in this work. The CdSe QDs were prepared with glycerol as the solvent, with sharp emission peak, full width at half maximum around 30?nm, and absorption peak from 475?nm to 510?nm. The reaction is environmental friendly and energy saving. What's more, the green synthesized CdSe QDs are coherence to the maximum remittance region of the solar spectrum and suitable as sensitizers to assemble onto TiO{sub 2} electrodes for cell devices application. What's more, the dynamic procedure of the carriers' excitation, transportation, and recombination in the QDSCs are discussed. Because the recombination of the electrons from the conduction band of TiO{sub 2}'s to the electrolyte affects the efficiency of the solar cells greatly, 3-Mercaptopropionic acid capped water-dispersible QDs were used to cover the surface of TiO{sub 2}. The resulting green synthesized CdSe QDSCs with Cu{sub 2}S as the electrode show a photovoltaic performance with a conversion efficiency of 3.39%.

  6. Theory of Electro-optic Modulation via a Quantum Dot Coupled to a Nano-resonator

    E-Print Network [OSTI]

    Arka Majumdar; Nicolas Manquest; Andrei Faraon; Jelena Vuckovic

    2009-11-27T23:59:59.000Z

    In this paper, we analyze the performance of an electro-optic modulator based on a single quantum dot strongly coupled to a nano-resonator, where electrical control of the quantum dot frequency is achieved via quantum confined Stark effect. Using realistic system parameters, we show that modulation speeds of a few tens of GHz are achievable with this system, while the energy per switching operation can be as small as 0.5 fJ. In addition, we study the non-linear distortion, and the effect of pure quantum dot dephasing on the performance of the modulator.

  7. Real-time effective-action approach to the Anderson quantum dot

    E-Print Network [OSTI]

    Sexty, Denes; Pawlowski, Jan

    2010-01-01T23:59:59.000Z

    The non-equilibrium time evolution of an Anderson quantum dot is investigated. The quantum dot is coupled between two leads forming a chemical-potential gradient. We use Kadanoff-Baym dynamic equations within a non-perturbative resummation of the s-channel bubble chains. The effect of the resummation leads to the introduction of a frequency-dependent 4-point vertex. The tunneling to the leads is taken into account exactly. The method allows the determination of the transient as well as stationary transport through the quantum dot, and results are compared with different schemes discussed in the literature (fRG, ISPI, tDMRG and QMC).

  8. Real-time effective-action approach to the Anderson quantum dot

    E-Print Network [OSTI]

    Denes Sexty; Thomas Gasenzer; Jan Pawlowski

    2010-12-20T23:59:59.000Z

    The non-equilibrium time evolution of an Anderson quantum dot is investigated. The quantum dot is coupled between two leads forming a chemical-potential gradient. We use Kadanoff-Baym dynamic equations within a non-perturbative resummation of the s-channel bubble chains. The effect of the resummation leads to the introduction of a frequency-dependent 4-point vertex. The tunneling to the leads is taken into account exactly. The method allows the determination of the transient as well as stationary transport through the quantum dot, and results are compared with different schemes discussed in the literature (fRG, ISPI, tDMRG and QMC).

  9. Strain-induced fundamental optical transition in (In,Ga)As/GaP quantum dots

    SciTech Connect (OSTI)

    Robert, C., E-mail: cedric.robert@insa-rennes.fr, E-mail: cedric.robert@tyndall.ie; Pedesseau, L.; Cornet, C.; Jancu, J.-M.; Even, J.; Durand, O. [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France)] [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France); Nestoklon, M. O. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)] [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Pereira da Silva, K. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain) [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Departamento de Física, Universidade Federal do Ceará, P.O. Box 6030, Fortaleza–CE, 60455-970 (Brazil); Alonso, M. I. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain)] [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Goñi, A. R. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain) [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); ICREA, Passeig Lluís Companys 23, 08010 Barcelona (Spain); Turban, P. [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)] [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)

    2014-01-06T23:59:59.000Z

    The nature of the ground optical transition in an (In,Ga)As/GaP quantum dot is thoroughly investigated through a million atoms supercell tight-binding simulation. Precise quantum dot morphology is deduced from previously reported scanning-tunneling-microscopy images. The strain field is calculated with the valence force field method and has a strong influence on the confinement potentials, principally, for the conduction band states. Indeed, the wavefunction of the ground electron state is spatially confined in the GaP matrix, close to the dot apex, in a large tensile strain region, having mainly Xz character. Photoluminescence experiments under hydrostatic pressure strongly support the theoretical conclusions.

  10. Gates controlled parallel-coupled double quantum dot on both single layer and bilayer graphene

    E-Print Network [OSTI]

    Lin-Jun Wang; Guo-Ping Guo; Da Wei; Gang Cao; Tao Tu; Ming Xiao; Guang-Can Guo; A. M. Chang

    2011-04-22T23:59:59.000Z

    Here we report the fabrication and quantum transport measurements of gates controlled parallel-coupled double quantum dot on both bilayer and single layer graphene. It is shown that the interdot coupling strength of the parallel double dots can be effectively tuned from weak to strong regime by both the in-plane plunger gates and back gate. All the relevant energy scales and parameters of the graphene parallel-coupled double dot can be extracted from the honeycomb charge stability diagrams revealed through the transport measurements.

  11. Optical spectra and intensities of graphene magnetic dot bound to a negatively charged Coulomb impurity

    SciTech Connect (OSTI)

    Lee, C. M., E-mail: mesimon-hk@yahoo.com.hk, E-mail: apkschan@cityu.edu.hk; Chan, K. S., E-mail: mesimon-hk@yahoo.com.hk, E-mail: apkschan@cityu.edu.hk [Department of Physics and Materials Science and Center for Functional Photonics, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Shenzhen Research Institute, City University of Hong Kong, Shenzhen (China)

    2014-07-28T23:59:59.000Z

    Employing numerical diagonalization, we study the optical properties of an electron in a monolayer-graphene magnetic dot bound to an off-center negatively charged Coulomb impurity based on the massless Dirac-Weyl model. Numerical results show that, since the electron-hole symmetry is broken by the Coulomb potential, the optical absorption spectra of the magnetic dot in the presence of a Coulomb impurity are different between the electron states and the hole states. Effects of both the magnetic field and the dot size on the absorption coefficient are presented as functions of the incident photon energies.

  12. National Air & Space Intelligence Center Holds Program About...

    Broader source: Energy.gov (indexed) [DOE]

    Intelligence Agency Support Team in September 2013. Photo by National Air and Space Intelligence Center. Dot Harris, Director of the Office of Economic Impact and...

  13. High performance tunnel injection quantum dot comb laser

    SciTech Connect (OSTI)

    Lee, C.-S.; Guo Wei; Basu, Debashish; Bhattacharya, Pallab [Department of Electrical Engineering and Computer Science, Solid State Electronics Laboratory, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

    2010-03-08T23:59:59.000Z

    A high-speed multiwavelength quantum dot comb laser, grown by molecular beam epitaxy, is demonstrated. The device is characterized with a 75.9 nm (full width at half maximum) and a 91.4 nm (DELTA{sub -15dB}) wide lasing spectrum. There are 105 and 185 simultaneously emitted longitudinal modes with a maximum channel intensity nonuniformity of less than 3 dB in the spectral range of 1231-1252 nm and 1274-1311 nm, respectively, for a laser with 1040 mum cavity length. The channel spacing can be tuned with cavity length and remains invariant in the temperature range of 300-323 K. The small signal modulation bandwidth is 7.5 GHz.

  14. Valley pair qubits in double quantum dots of gapped graphene

    E-Print Network [OSTI]

    G. Y. Wu; N. -Y. Lue; L. Chang

    2011-07-03T23:59:59.000Z

    The rise of graphene opens a new door to qubit implementation, as discussed in the recent proposal of valley pair qubits in double quantum dots of gapped graphene (Wu et al., arXiv: 1104.0443 [cond-mat.mes-hall]). The work here presents the comprehensive theory underlying the proposal. It discusses the interaction of electrons with external magnetic and electric fields in such structures. Specifically, it examines a strong, unique mechanism, i.e., the analogue of the 1st-order relativistic effect in gapped graphene. This mechanism is state mixing free and allows, together with the electrically tunable exchange coupling, a fast, all-electric manipulation of qubits via electric gates, in the time scale of ns. The work also looks into the issue of fault tolerance in a typical case, yielding at 10oK a long qubit coherence time (~O(ms)).

  15. Fluorescence quenching of CdSe quantum dots on graphene

    SciTech Connect (OSTI)

    Guo, Xi Tao; Hua Ni, Zhen, E-mail: zhni@seu.edu.cn; Yan Nan, Hai; Hui Wang, Wen [Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189 (China)] [Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189 (China); Yan Liao, Chun [Physics Department, National Photoelectric Technology and Functional Materials and Application of Science and Technology International Cooperation Base, Northwest University, Xi'an 710069 (China)] [Physics Department, National Photoelectric Technology and Functional Materials and Application of Science and Technology International Cooperation Base, Northwest University, Xi'an 710069 (China); Zhang, Yan; Wei Zhao, Wei [Jiangsu Key Laboratory for Design and Fabrication of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189 (China)] [Jiangsu Key Laboratory for Design and Fabrication of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189 (China)

    2013-11-11T23:59:59.000Z

    We studied systematically the fluorescence quenching of CdSe quantum dots (QDs) on graphene and its multilayers, as well as graphene oxide (GO) and reduced graphene oxide (rGO). Raman intensity of QDs was used as a quantitatively measurement of its concentration in order to achieve a reliable quenching factor (QF). It was found that the QF of graphene (?13.1) and its multilayers is much larger than rGO (?4.4), while GO (?1.5) has the lowest quenching efficiency, which suggests that the graphitic structure is an important factor for quenching the fluorescence of QDs. It was also revealed that the QF of graphene is not strongly dependent on its thicknesses.

  16. Gate-Tunable Graphene Quantum Dot and Dirac Oscillator

    E-Print Network [OSTI]

    Abdelhadi Belouad; Ahmed Jellal; Youness Zahidi

    2015-05-29T23:59:59.000Z

    We obtain the solution of the Dirac equation in (2+1) dimensions in the presence of a constant magnetic field normal to the plane together with a two-dimensional Dirac-oscillator potential coupling. We study the energy spectrum of graphene quantum dot (QD) defined by electrostatic gates. We give discussions of our results based on different physical settings, whether the cyclotron frequency is similar or larger/smaller compared to the oscillator frequency. This defines an effective magnetic field that produces the effective quantized Landau levels. We study analytically such field in gate-tunable graphene QD and show that our structure allow us to control the valley degeneracy. Finally, we compare our results with already published work and also discuss the possible applications of such QD.

  17. Gate-Tunable Graphene Quantum Dot and Dirac Oscillator

    E-Print Network [OSTI]

    Belouad, Abdelhadi; Zahidi, Youness

    2015-01-01T23:59:59.000Z

    We obtain the solution of the Dirac equation in (2+1) dimensions in the presence of a constant magnetic field normal to the plane together with a two-dimensional Dirac-oscillator potential coupling. We study the energy spectrum of graphene quantum dot (QD) defined by electrostatic gates. We give discussions of our results based on different physical settings, whether the cyclotron frequency is similar or larger/smaller compared to the oscillator frequency. This defines an effective magnetic field that produces the effective quantized Landau levels. We study analytically such field in gate-tunable graphene QD and show that our structure allow us to control the valley degeneracy. Finally, we compare our results with already published work and also discuss the possible applications of such QD.

  18. Energy spectra of two electrons in a circular quantum dot

    E-Print Network [OSTI]

    Anjana Sinha; Y. P. Varshni

    2002-08-27T23:59:59.000Z

    The electron interaction energy of two interacting electrons in a circular quantum dot (with hard wall confinement) is investigated in the framework of the semi-classical Wentzel-Kramers-Brillouin (WKB) approximation. The two electrons are assumed to be in an infinitely deep well of radius $r_0$, in a simple configuration with one electron fixed at the origin. The corresponding Schrodinger equation, with hard wall boundary conditions, is also solved exactly by numerical integration. It is observed that the agreement between the two energy values is quite good, suggesting that the WKB approximation works well for such a confined quantum system as well. This may provide motivation to extend this to more realistic confined potentials.

  19. Location deterministic biosensing from quantum-dot-nanowire assemblies

    SciTech Connect (OSTI)

    Liu, Chao [Materials Science and Engineering Program, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States); Kim, Kwanoh [Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States); Fan, D. L., E-mail: dfan@austin.utexas.edu [Materials Science and Engineering Program, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States); Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States)

    2014-08-25T23:59:59.000Z

    Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10?nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively understood as the synergetic effects of dielectrophoretic (DEP) and alternating current electroosmosis (ACEO) due to AC electric fields. The QD-nanowire hybrid sensors operate uniquely by concentrating bioanalytes to QDs on the tips of nanowires before detection, offering much enhanced efficiency and sensitivity, in addition to the position-predictable rationality. This research could result in advances in QD-based biomedical detection and inspires an innovative approach for fabricating various QD-based nanodevices.

  20. Optimal tunneling enhances the quantum photovoltaic effect in double quantum dots

    E-Print Network [OSTI]

    Wang, Chen

    We investigate the quantum photovoltaic effect in double quantum dots by applying the nonequilibrium quantum master equation. A drastic suppression of the photovoltaic current is observed near the open circuit voltage, ...

  1. Luminescent, quantum dot-based anti-reflective coatings for crystalline silicon photovoltaics

    E-Print Network [OSTI]

    Bruer, Garrett (Garrett A.)

    2010-01-01T23:59:59.000Z

    This thesis demonstrates and evaluates the potential application of luminescent quantum dot/polymer solutions on crystalline silicon photovoltaics. After spin coating the QD/polymer onto silicon photodiodes, an increase ...

  2. Physica E 32 (2006) 1416 Tuning the cross-gap transition energy of a quantum dot

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    2006-01-01T23:59:59.000Z

    ; Spectroscopy; Energy tuning Self-assembled semiconductor quantum dots (QDs) are of great interest for quantum resistance bridge circuit in combination with a lock in amplifier is used to measure the change in resistance

  3. Optimization of a microwave resonator cavity to perform electron spin resonance measurements on quantum dots

    E-Print Network [OSTI]

    Burger, Anat

    2006-01-01T23:59:59.000Z

    This thesis attempts to improve on an ongoing experiment of detecting electron spin resonance (ESR) on AlGaAs/GaAs lateral quantum dots. The experiment is performed in a 2.5 Tesla magnetic field at temperatures around ...

  4. Quantum Dots Promise to Significantly Boost Solar Cell Efficiencies (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2013-08-01T23:59:59.000Z

    In the search for a third generation of solar-cell technologies, a leading candidate is the use of 'quantum dots' -- tiny spheres of semiconductor material measuring only about 2-10 billionths of a meter in diameter. Quantum dots have the potential to dramatically increase the efficiency of converting sunlight into energy -- perhaps even doubling it in some devices -- because of their ability to generate more than one bound electron-hole pair, or exciton, per incoming photon. NREL has produced quantum dots using colloidal suspensions; then, using molecular self-assembly, they have been fabricated into the first-ever quantum-dot solar cells. While these devices operate with only 4.4% efficiency, they demonstrate the capability for low-cost manufacturing.

  5. Efficiency loss mechanisms in colloidal quantum-dot light-emitting diodes

    E-Print Network [OSTI]

    Shirasaki, Yasuhiro

    2013-01-01T23:59:59.000Z

    Saturated and tunable emission colors make colloidal quantum-dot light-emitting diodes (QD-LEDs) interesting for the next generation of display and lighting technologies. However, there still remain various hurdles to the ...

  6. Multispectral imaging via luminescent down-shifting with colloidal quantum dots

    E-Print Network [OSTI]

    Jaworski, Frank B.

    The high infrared quantum yield, continuous absorption spectrum, and band edge tunability of colloidal quantum dots (QD) has opened up new opportunities to use luminescent down shifting for multispectral imaging in the ...

  7. Development of low-temperature solution-processed colloidal quantum dot-based solar cells

    E-Print Network [OSTI]

    Chang, Liang-Yi, Ph. D. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    Solution-processed solar cells incorporating organic semiconductors and inorganic colloidal quantum dots (QDs) are potential alternatives to conventional solar cells fabricated via vacuum or high-temperature sintering ...

  8. The physics and chemistry of transport in CdSe quantum dot solids

    E-Print Network [OSTI]

    Jarosz, Mirna, 1981-

    2004-01-01T23:59:59.000Z

    Semiconductor quantum dots (QDs) have tunable opto-electronic properties and can be chemically synthesized and manipulated with ease, making them a promising novel material for many diverse applications. An understanding ...

  9. Exchange Control of Nuclear Spin Diffusion in a Double Quantum Dot

    E-Print Network [OSTI]

    Reilly, D. J.

    The influence of gate-controlled two-electron exchange on the relaxation of nuclear polarization in small ensembles (N?10[superscript 6]) of nuclear spins is examined in a GaAs double quantum dot system. Waiting in the ...

  10. Electrical excitation of colloidally synthesized quantum dots in metal oxide structures

    E-Print Network [OSTI]

    Wood, Vanessa Claire

    2010-01-01T23:59:59.000Z

    This thesis develops methods for integrating colloidally synthesized quantum dots (QDs) and metal oxides in optoelectronic devices, presents three distinct light emitting devices (LEDs) with metal oxides surrounding a QD ...

  11. Nuclear spin dynamics in double quantum dots: Fixed points, transients, and intermittency

    E-Print Network [OSTI]

    Rudner, M. S.

    Transport through spin-blockaded quantum dots provides a means for electrical control and detection of nuclear spin dynamics in the host material. Although such experiments have become increasingly popular in recent years, ...

  12. Lateral heterojunction photodetector consisting of molecular organic and colloidal quantum dot thin films

    E-Print Network [OSTI]

    exception being the dye- sensitized solar cell.3 Owing to its unique geometry, the present device also and that is sensitized across visible wavelengths by a thin film of colloidal CdSe nanocrystal quantum dots QDs . High

  13. Gain dynamics of quantum dot devices for dual-state operation

    SciTech Connect (OSTI)

    Kaptan, Y., E-mail: yuecel.kaptan@physik.tu-berlin.de; Herzog, B.; Kolarczik, M.; Owschimikow, N.; Woggon, U. [Institut für Optik und Atomare Physik, Technische Universität Berlin, Berlin (Germany); Schmeckebier, H.; Arsenijevi?, D.; Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin (Germany); Mikhelashvili, V.; Eisenstein, G. [Technion Institute of Technology, Faculty of Electrical Engineering, Haifa (Israel)

    2014-06-30T23:59:59.000Z

    Ground state gain dynamics of In(Ga)As-quantum dot excited state lasers are investigated via single-color ultrafast pump-probe spectroscopy below and above lasing threshold. Two-color pump-probe experiments are used to localize lasing and non-lasing quantum dots within the inhomogeneously broadened ground state. Single-color results yield similar gain recovery rates of the ground state for lasing and non-lasing quantum dots decreasing from 6 ps to 2 ps with increasing injection current. We find that ground state gain dynamics are influenced solely by the injection current and unaffected by laser operation of the excited state. This independence is promising for dual-state operation schemes in quantum dot based optoelectronic devices.

  14. InGaAs Quantum Dots Coupled to a Reservoir of Nonequilibrium Free Carriers

    E-Print Network [OSTI]

    Laemmlin, Matthias

    We discuss the impact of a 2D-charged carrier reservoir for high-speed optical amplification and modulated lasing in quantum dot (QD)-based devices by testing the amplification of short trains of high power, femtosecond ...

  15. Solar Hydrogen Production Using Carbon Quantum Dots and a Molecular Nickel Catalyst

    E-Print Network [OSTI]

    Martindale, Benjamin C. M.; Hutton, Georgina A. M.; Caputo, Christine A.; Reisner, Erwin

    2015-04-13T23:59:59.000Z

    Solar Hydrogen Production Using Carbon Quantum Dots and a Molecular Nickel Catalyst Benjamin C. M. Martindale,† Georgina A. M. Hutton,† Christine A. Caputo, and Erwin Reisner* Christian Doppler Laboratory for Sustainable SynGas Chemistry, Department...

  16. Mechanism of lateral ordering of InP dots grown on InGaP layers

    SciTech Connect (OSTI)

    Bortoleto, J.R.R.; Gutierrez, H.R.; Cotta, M.A.; Bettini, J. [Instituto de Fisica Gleb Wataghin, DFA, UNICAMP, CP 6165, 13081-970 Campinas-SP (Brazil); Laboratorio Nacional de Luz Sincrotron, CP 6192, 13084-971, Campinas-SP (Brazil)

    2005-07-04T23:59:59.000Z

    The mechanisms leading to the spontaneous formation of a two-dimensional array of InP/InGaP dots grown by chemical-beam epitaxy are discussed. Samples where the InGaP buffer layer was grown at different conditions were characterized by transmission electron microscopy. Our results indicate that a periodic strain field related to lateral two-dimensional compositional modulation in the InGaP buffer layer determines the dot nucleation positions during InP growth. Although the periodic strain field in the InGaP is large enough to align the InP dots, both their shape and optical properties are effectively unaltered. This result shows that compositional modulation can be used as a tool for in situ dot positioning.

  17. Narrow-Band Absorption-Enhanced Quantum Dot/J-Aggregate Conjugates

    E-Print Network [OSTI]

    Walker, Brian J.

    We report narrow-band absorption enhancement of semiconductor nanocrystals via Förster resonance energy transfer from cyanine J-aggregates. These J-aggregated dyes associate electrostatically with short quantum-dot (QD) ...

  18. Theoretical study of intraband optical transitions in conduction band of dot-in-a-well system

    SciTech Connect (OSTI)

    Chaganti, Venkata R.; Apalkov, Vadym [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30302 USA. (Georgia)] [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30302 USA. (Georgia)

    2014-02-15T23:59:59.000Z

    We study numerically absorption optical spectra of n-doped InAs/In{sub 015}Ga{sub 085}As/GaAs quantum dot-in-a-well systems. The absorption spectra are mainly determined by the size of a quantum dot and have weak dependence on the thickness of quantum well and position of the dot in a well. The dot-in-a-well system is sensitive to both in-plane and out-of-plane polarizations of the incident light with much stronger absorption intensities for the in-plane-polarized light. The absorption spectrum of in-plane-polarized light has also a multi-peak structure with two or three peaks of comparable intensities, while the absorption spectrum of out-of-plane polarized light has a single well-pronounced peak.

  19. Two photon luminescence from quantum dots using broad and narrowband ultrafast laser pulses

    E-Print Network [OSTI]

    Balasubramanian, Haribhaskar

    2008-10-10T23:59:59.000Z

    TWO PHOTON LUMINESCENCE FROM QUANTUM DOTS USING BROAD AND NARROWBAND ULTRAFAST LASER PULSES A Thesis by HARIBHASKAR BALASUBRAMANIAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 2007 Major Subject: Biomedical Engineering TWO PHOTON LUMINESCENCE FROM QUANTUM DOTS USING BROAD AND NARROWBAND ULTRAFAST LASER PULSES A Thesis by HARIBHASKAR...

  20. Off-resonant coupling between a single quantum dot and a nanobeam photonic crystal cavity

    E-Print Network [OSTI]

    Armand Rundquist; Arka Majumdar; Jelena Vuckovic

    2011-10-05T23:59:59.000Z

    We demonstrate off-resonant coupling between a single quantum dot and a nanobeam photonic crystal cavity, under resonant excitation of the quantum dot or the cavity. These results are consistent with previous descriptions of off-resonant coupling as an incoherent phonon-mediated process. The extension of this phenomenon to a nanobeam photonic crystal cavity presents interesting possibilities for coherent control of this interaction by tailoring the phonon density of states.

  1. Ultrafast photon-photon interaction in a strongly coupled quantum dot-cavity system

    E-Print Network [OSTI]

    Dirk Englund; Arka Majumdar; Michal Bajcsy; Andrei Faraon; Pierre Petroff; Jelena vuckovic

    2011-07-14T23:59:59.000Z

    We study dynamics of the interaction between two weak light beams mediated by a strongly coupled quantum dot-photonic crystal cavity system. First, we perform all optical switching of a weak continuous-wave signal with a pulsed control beam, and then perform switching between two pulsed beams (40ps pulses) at the single photon level. Our results show that the quantum dot-nanocavity system creates strong, controllable interactions at the single photon level.

  2. Control of excitation transfer in coupled quantum dots by a nonresonant laser pulse

    E-Print Network [OSTI]

    P. A. Golovinski; V. A. Astapenko; A. V. Yakovets

    2014-08-06T23:59:59.000Z

    We study theoretically fast transfer of excitons between pairs of coupled quantum dots driven by the optical Stark effect that is produced by a short nonresonant laser pulse. The Schr\\"odinger equation, in which the relative position of energy levels of quantum dot subsystems is time-dependent, is solved numerically. Computer simulation shows a way to achieve efficient excitation transfer by the action of a picosecond laser pulse with a rectangular envelope function.

  3. Regulatory compliance guide for DOT-7A type A packaging design

    SciTech Connect (OSTI)

    Kelly, D.L.

    1996-06-04T23:59:59.000Z

    The purpose of this guide is to provide instruction for assuring that the regulatory design requirements for a DOT-7A Type A packaging are met. This guide also supports the testing and evaluation activities that are performed on new packaging designs by a DOE-approved test facility through the DOE`s DOT-7A Test Program. This Guide was updated to incorporate regulatory changes implemented by HM-169A (49 CFR, `Transportation`).

  4. SU(4) Kondo Effect in Carbon Nanotube Quantum Dots: Kondo Effect without Charge Quantization

    E-Print Network [OSTI]

    Finkelstein, Gleb

    for 1 electron: Double dots, dots with symmetries: D. Boese et al., PRB (2002) L. Borda et al., PRL (2003) K. Le Hur and P. Simon, PRB (2003) G. Zarand et al., SSC (2003) W. Izumida et al., J.R. Krishnamurthy, PRL (2005) C.A. Busser and G.B. Martins, PRB (2007) 2-e Kondo in nanotubes ­ triplet or SU(4) W

  5. SUNY/Buffalo Developing High-Efficiency Colloidal Quantum Dot Phosphors

    Broader source: Energy.gov [DOE]

    The State University of New York at Buffalo is working to reduce the cost and increase the performance of LEDs for general illumination by developing high-efficiency colloidal quantum dot phosphors to replace conventional phosphors (i.e., those placed directly on the chip). Colloidal quantum dot phosphors are nanocrystal emitters and contain no rare-earth elements. What's more, it's possible to tune the emission wavelength merely by changing their size.

  6. Electronic waiting-time distribution of a quantum-dot spin valve

    E-Print Network [OSTI]

    Björn Sothmann

    2014-10-27T23:59:59.000Z

    We discuss the electronic waiting-time distribution of a quantum-dot spin valve, i.e. a single-level quantum dot coupled to two ferromagnetic electrodes with magnetizations that can point in arbitrary directions. We demonstrate that the rich transport physics of this setup such as dynamical channel blockade and spin precession in an interaction-driven exchange field shows up in the waiting-time distribution and analyze the conditions necessary to observe the various effects.

  7. The effect of Coulomb interactions on thermoelectric properties of quantum dots

    SciTech Connect (OSTI)

    Zimbovskaya, Natalya A. [Department of Physics and Electronics, University of Puerto Rico-Humacao, CUH Station, Humacao, Puerto Rico 00791, USA and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Ruco 00931 (United States)] [Department of Physics and Electronics, University of Puerto Rico-Humacao, CUH Station, Humacao, Puerto Rico 00791, USA and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Ruco 00931 (United States)

    2014-03-14T23:59:59.000Z

    Thermoelectric effects in a quantum dot coupled to the source and drain charge reservoirs are explored using a nonequilibrium Green's functions formalism beyond the Hartree-Fock approximation. Thermal transport is analyzed within a linear response regime. A transition from Coulomb blockade regime to Kondo regime in thermoelectric transport through a single-level quantum dot is traced using unified approximations for the relevant Green's functions.

  8. (In,Mn)As quantum dots: Molecular-beam epitaxy and optical properties

    SciTech Connect (OSTI)

    Bouravleuv, A. D., E-mail: bour@mail.ioffe.ru; Nevedomskii, V. N. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Ubyivovk, E. V. [St. Petersburg State University (Russian Federation)] [St. Petersburg State University (Russian Federation); Sapega, V. F. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Khrebtov, A. I. [St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation)] [St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation); Samsonenko, Yu. B.; Cirlin, G. E.; Ustinov, V. M. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-08-15T23:59:59.000Z

    Self-assembled (In,Mn)As quantum dots are synthesized by molecular-beam epitaxy on GaAs (001) substrates. The experimental results obtained by transmission electron microscopy show that doping of the central part of the quantum dots with Mn does not bring about the formation of structural defects. The optical properties of the samples, including those in external magnetic fields, are studied.

  9. GaN/AlN Quantum Dots for Single Qubit Emitters M. Winkelnkemper

    E-Print Network [OSTI]

    Nabben, Reinhard

    GaN/AlN Quantum Dots for Single Qubit Emitters M. Winkelnkemper , R. Seguin, S. Rodt, A. Hoffmann-plane GaN/AlN quantum dots (QDs) with focus on their potential as sources of single polarized photons emission lines from single InGaN/GaN [4­11] and GaN/AlN QDs grown on the c-plane [12­16] and a-plane [17

  10. A comparison between semi-spheroid- and dome-shaped quantum dots coupled to wetting layer

    SciTech Connect (OSTI)

    Shahzadeh, Mohammadreza; Sabaeian, Mohammad, E-mail: Sabaeian@scu.ac.ir [Physics Department, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, 61357-43135 (Iran, Islamic Republic of)

    2014-06-15T23:59:59.000Z

    During the epitaxial growth method, self-assembled semi-spheroid-shaped quantum dots (QDs) are formed on the wetting layer (WL). However for sake of simplicity, researchers sometimes assume semi-spheroid-shaped QDs to be dome-shaped (hemisphere). In this work, a detailed and comprehensive study on the difference between electronic and transition properties of dome- and semi-spheroid-shaped quantum dots is presented. We will explain why the P-to-S intersubband transition behaves the way it does. The calculated results for intersubband P-to-S transition properties of quantum dots show two different trends for dome-shaped and semi-spheroid-shaped quantum dots. The results are interpreted using the probability of finding electron inside the dome/spheroid region, with emphasis on the effects of wetting layer. It is shown that dome-shaped and semi-spheroid-shaped quantum dots feature different electronic and transition properties, arising from the difference in lateral dimensions between dome- and semi-spheroid-shaped QDs. Moreover, an analogy is presented between the bound S-states in the quantum dots and a simple 3D quantum mechanical particle in a box, and effective sizes are calculated. The results of this work will benefit researchers to present more realistic models of coupled QD/WL systems and explain their properties more precisely.

  11. Engineering of quantum dot photon sources via electro-elastic fields

    E-Print Network [OSTI]

    Rinaldo Trotta; Armando Rastelli

    2015-03-01T23:59:59.000Z

    The possibility to generate and manipulate non-classical light using the tools of mature semiconductor technology carries great promise for the implementation of quantum communication science. This is indeed one of the main driving forces behind ongoing research on the study of semiconductor quantum dots. Often referred to as artificial atoms, quantum dots can generate single and entangled photons on demand and, unlike their natural counterpart, can be easily integrated into well-established optoelectronic devices. However, the inherent random nature of the quantum dot growth processes results in a lack of control of their emission properties. This represents a major roadblock towards the exploitation of these quantum emitters in the foreseen applications. This chapter describes a novel class of quantum dot devices that uses the combined action of strain and electric fields to reshape the emission properties of single quantum dots. The resulting electro-elastic fields allow for control of emission and binding energies, charge states, and energy level splittings and are suitable to correct for the quantum dot structural asymmetries that usually prevent these semiconductor nanostructures from emitting polarization-entangled photons. Key experiments in this field are presented and future directions are discussed.

  12. Effect of quantum dot position and background doping on the performance of quantum dot enhanced GaAs solar cells

    SciTech Connect (OSTI)

    Driscoll, Kristina, E-mail: kmdsps@rit.edu; Bennett, Mitchell F.; Polly, Stephen J.; Forbes, David V.; Hubbard, Seth M., E-mail: smhsps@rit.edu [NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, New York (United States)

    2014-01-13T23:59:59.000Z

    The effect of the position of InAs quantum dots (QD) within the intrinsic region of pin-GaAs solar cells is reported. Simulations suggest placing the QDs in regions of reduced recombination enables a recovery of open-circuit voltage (V{sub OC}). Devices with the QDs placed in the center and near the doped regions of a pin-GaAs solar cell were experimentally investigated. While the V{sub OC} of the emitter-shifted device was degraded, the center and base-shifted devices exhibited V{sub OC} comparable to the baseline structure. This asymmetry is attributed to background doping which modifies the recombination profile and must be considered when optimizing QD placement.

  13. Enhanced Two-Photon Processes in Quantum Dots inside Photonic Crystal Nanocavities and Quantum Information Processing Applications

    E-Print Network [OSTI]

    Ziliang Lin; Jelena Vuckovic

    2009-07-02T23:59:59.000Z

    We show that the two-photon transition rates of quantum dots coupled to nanocavities are enhanced by up to 8 orders of magnitude relative to quantum dots in bulk host. We then propose how to take advantage of this enhancement to implement coherent quantum dot excitation by two-photon absorption, entangled photon pair generation by two-photon spontaneous emission, and single-photon generation at telecommunication wavelengths by two-photon stimulated and spontaneous emission.

  14. Quasiresonant excitation of InP/InGaP quantum dots using second harmonic generated in a photonic crystal cavity

    E-Print Network [OSTI]

    Vuckovic, Jelena

    Quasiresonant excitation of InP/InGaP quantum dots using second harmonic generated in a photonic://apl.aip.org/about/rights_and_permissions #12;Quasiresonant excitation of InP/InGaP quantum dots using second harmonic generated in a photonic signal to noise quasiresonant excitation of InP/InGaP quantum dots. The excitation is provided via second

  15. Optical Properties of Wurtzite GaN and ZnO Quantum Dots Vladimir A. Fonoberov and Alexander A. Balandin

    E-Print Network [OSTI]

    Fonoberov, Vladimir

    Optical Properties of Wurtzite GaN and ZnO Quantum Dots Vladimir A. Fonoberov and Alexander A-Riverside, Riverside, California 92521, U.S.A. ABSTRACT We have investigated exciton states in wurtzite GaN/AlN and ZnO quantum dots. A strong piezoelectric field in GaN/AlN quantum dots is found to tilt conduction and valence

  16. Investigations of segregation phenomena in highly strained Mn-doped Ge wetting layers and Ge quantum dots embedded in silicon

    SciTech Connect (OSTI)

    Prestat, E., E-mail: eric.prestat@gmail.com; Porret, C.; Favre-Nicolin, V.; Tainoff, D.; Boukhari, M.; Bayle-Guillemaud, P.; Jamet, M.; Barski, A., E-mail: andre.barski@cea.com [INAC, SP2M, CEA and Université Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

    2014-03-10T23:59:59.000Z

    In this Letter, we investigate manganese diffusion and the formation of Mn precipitates in highly strained, few monolayer thick, Mn-doped Ge wetting layers and nanometric size Ge quantum dot heterostructures embedded in silicon. We show that in this Ge(Mn)/Si system manganese always precipitates and that the size and the position of Mn clusters (precipitates) depend on the growth temperature. At high growth temperature, manganese strongly diffuses from germanium to silicon, whereas decreasing the growth temperature reduces the manganese diffusion. In the germanium quantum dots layers, Mn precipitates are detected, not only in partially relaxed quantum dots but also in fully strained germanium wetting layers between the dots.

  17. Impact of heavy hole-light hole coupling on optical selection rules in GaAs quantum dots

    SciTech Connect (OSTI)

    Belhadj, T.; Amand, T.; Kunz, S.; Marie, X.; Urbaszek, B. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Kunold, A. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Departamento de Ciencias Basicas, UAM-A, Col. Reynosa Tamaulipas, 02200 Mexico D.F. (Mexico); Simon, C.-M. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); CNRS-UPS, LCAR, IRSAMC, Universite de Toulouse, 31062 Toulouse (France); Kuroda, T.; Abbarchi, M.; Mano, T.; Sakoda, K. [National Institute for Material Science, Namiki 1-1, Tsukuba 305-0044 (Japan)

    2010-08-02T23:59:59.000Z

    We report strong heavy hole-light hole mixing in GaAs quantum dots grown by droplet epitaxy. Using the neutral and charged exciton emission as a monitor we observe the direct consequence of quantum dot symmetry reduction in this strain free system. By fitting the polar diagram of the emission with simple analytical expressions obtained from k{center_dot}p theory we are able to extract the mixing that arises from the heavy-light hole coupling due to the geometrical asymmetry of the quantum dot.

  18. Electrically driven single photon emission from a CdSe/ZnSSe single quantum dot at 200?K

    SciTech Connect (OSTI)

    Quitsch, Wolf; Kümmell, Tilmar; Bacher, Gerd [Werkstoffe der Elektrotechnik and CENIDE, Universität Duisburg-Essen, Bismarckstraße 81, 47057 Duisburg (Germany); Gust, Arne; Kruse, Carsten; Hommel, Detlef [Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28334 Bremen (Germany)

    2014-09-01T23:59:59.000Z

    High temperature operation of an electrically driven single photon emitter based on a single epitaxial quantum dot is reported. CdSe/ZnSSe/MgS quantum dots are embedded into a p-i-n diode architecture providing almost background free excitonic and biexcitonic electroluminescence from individual quantum dots through apertures in the top contacts. Clear antibunching with g{sup 2}(??=?0)?=?0.28?±?0.20 can be tracked up to T?=?200?K, representing the highest temperature for electrically triggered single photon emission from a single quantum dot device.

  19. Using quantum dots to tag subsurface damage in lapped and polished glass samples

    SciTech Connect (OSTI)

    Williams, Wesley B.; Mullany, Brigid A.; Parker, Wesley C.; Moyer, Patrick J.; Randles, Mark H.

    2009-09-20T23:59:59.000Z

    Grinding, lapping, and polishing are finishing processes used to achieve critical surface parameters in a variety of precision optical and electronic components. As these processes remove material from the surface through mechanical and chemical interactions, they may induce a damaged layer of cracks, voids, and stressed material below the surface. This subsurface damage (SSD) can degrade the performance of a final product by creating optical aberrations due to diffraction, premature failure in oscillating components, and a reduction in the laser induced damage threshold of high energy optics. As these defects lie beneath the surface, they are difficult to detect, and while many methods are available to detect SSD, they can have notable limitations regarding sample size and type, preparation time, or can be destructive in nature. The authors tested a nondestructive method for assessing SSD that consisted of tagging the abrasive slurries used in lapping and polishing with quantum dots (nano-sized fluorescent particles). Subsequent detection of fluorescence on the processed surface is hypothesized to indicate SSD. Quantum dots that were introduced to glass surfaces during the lapping process were retained through subsequent polishing and cleaning processes. The quantum dots were successfully imaged by both wide field and confocal fluorescence microscopy techniques. The detected fluorescence highlighted features that were not observable with optical or interferometric microscopy. Atomic force microscopy and additional confocal microscope analysis indicate that the dots are firmly embedded in the surface but do not appear to travel deep into fractures beneath the surface. Etching of the samples exhibiting fluorescence confirmed that SSD existed. SSD-free samples exposed to quantum dots did not retain the dots in their surfaces, even when polished in the presence of quantum dots.

  20. Ultrafast dynamics of strongly coupled quantum dot-nanocavity systems

    E-Print Network [OSTI]

    Kai Müller; Kevin A. Fischer; Armand Rundquist; Constantin Dory; Konstantinos G. Lagoudakis; Tomas Sarmiento; Victoria Borish; Yousif A. Kelaita; Jelena Vu?kovi?

    2015-03-18T23:59:59.000Z

    We investigate the influence of exciton-phonon coupling on the dynamics of a strongly coupled quantum dot-photonic crystal cavity system and explore the effects of this interaction on different schemes for non-classical light generation. By performing time-resolved measurements, we map out the detuning-dependent polariton lifetime and extract the spectrum of the polariton-to-phonon coupling. Photon-blockade experiments are presented for different pulse-length and detuning conditions that are in very good agreement with quantum-optical simulations; we demonstrate that achieving high-fidelity photon blockade requires an intricate understanding of this parameter space. Furthermore, we show that detuned photon blockade, which is more efficient than resonant photon blockade, is also more dramatically affected by phonons. Finally, we achieve coherent control of the polariton states of a strongly coupled system and demonstrate that their efficient coupling to phonons can be exploited for novel concepts in high-fidelity single photon generation.

  1. PROPERTIES OF UMBRAL DOTS FROM STRAY LIGHT CORRECTED HINODE FILTERGRAMS

    SciTech Connect (OSTI)

    Louis, Rohan E.; Mathew, Shibu K.; Bayanna, A. Raja [Udaipur Solar Observatory, Physical Research Laboratory, Dewali, Badi Road, Udaipur, Rajasthan 313004 (India); Rubio, Luis R. Bellot [Instituto de Astrofisica de Andalucia (CSIC), Apartado de Correos 3004, 18080 Granada (Spain); Ichimoto, Kiyoshi [Kwasan and Hida Observatories, Kyoto University, Yamashina-ku, Kyoto 607-8417 (Japan); Ravindra, B., E-mail: eugene@prl.res.in [Indian Institute of Astrophysics, II Block, Koramangla, Bangalore 560034 (India)

    2012-06-20T23:59:59.000Z

    High-resolution blue continuum filtergrams from Hinode are employed to study the umbral fine structure of a regular unipolar sunspot. The removal of scattered light from the images increases the rms contrast by a factor of 1.45 on average. Improvement in image contrast renders identification of short filamentary structures resembling penumbrae that are well separated from the umbra-penumbra boundary and comprise bright filaments/grains flanking dark filaments. Such fine structures were recently detected from ground-based telescopes and have now been observed with Hinode. A multi-level tracking algorithm was used to identify umbral dots (UDs) in both the uncorrected and corrected images and to track them in time. The distribution of the values describing the photometric and geometric properties of UDs is more easily affected by the presence of stray light while it is less severe in the case of kinematic properties. Statistically, UDs exhibit a peak intensity, effective diameter, lifetime, horizontal speed, and a trajectory length of 0.29I{sub QS}, 272 km, 8.4 minutes, 0.45 km s{sup -1}, and 221 km, respectively. The 2 hr 20 minute time sequence depicts several locations where UDs tend to appear and disappear repeatedly with various time intervals. The correction for scattered light in the Hinode filtergrams facilitates photometry of umbral fine structure, which can be related to results obtained from larger telescopes and numerical simulations.

  2. Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes

    SciTech Connect (OSTI)

    Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)] [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

    2013-01-28T23:59:59.000Z

    We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

  3. Inhibition of plasmonically enhanced interdot energy transfer in quantum dot solids via photo-oxidation

    SciTech Connect (OSTI)

    Sadeghi, S. M. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Nano and Micro Device Center, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Nejat, A.; West, R. G. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States)

    2012-11-15T23:59:59.000Z

    We studied the impact of photophysical and photochemical processes on the interdot Forster energy transfer in monodisperse CdSe/ZnS quantum dot solids. For this, we investigated emission spectra of CdSe/ZnS quantum dot solids in the vicinity of gold metallic nanoparticles coated with chromium oxide. The metallic nanoparticles were used to enhance the rate of the energy transfer between the quantum dots, while the chromium oxide coating led to significant increase of their photo-oxidation rates. Our results showed that irradiation of such solids with a laser beam can lead to unique spectral changes, including narrowing and blue shift. We investigate these effects in terms of inhibition of the plasmonically enhanced interdot energy transfer between quantum dots via the chromium-oxide accelerated photo-oxidation process. We demonstrate this considering energy-dependent rate of the interdot energy transfer process, plasmonic effects, and the way photo-oxidation enhances non-radiative decay rates of quantum dots with different sizes.

  4. Preparation of Non-equilibrium Nuclear Spin States in Double Quantum Dots

    E-Print Network [OSTI]

    M. Gullans; J. J. Krich; J. M. Taylor; B. I. Halperin; M. D. Lukin

    2014-07-25T23:59:59.000Z

    We theoretically study the dynamic polarization of lattice nuclear spins in GaAs double quantum dots containing two electrons. In our prior work [Phys. Rev. Lett. 104, 226807 (2010)] we identified three regimes of long-term dynamics, including the build up of a large difference in the Overhauser fields across the dots, the saturation of the nuclear polarization process associated with formation of so-called "dark states," and the elimination of the difference field. In particular, when the dots are different sizes we found that the Overhauser field becomes larger in the smaller dot. Here we present a detailed theoretical analysis of these problems including a model of the polarization dynamics and the development of a new numerical method to efficiently simulate semiclassical central-spin problems. When nuclear spin noise is included, the results agree with our prior work indicating that large difference fields and dark states are stable configurations, while the elimination of the difference field is unstable; however, in the absence of noise we find all three steady states are achieved depending on parameters. These results are in good agreement with dynamic nuclear polarization experiments in double quantum dots.

  5. The impact of disorder on charge transport in three dimensional quantum dot resonant tunneling structures

    SciTech Connect (OSTI)

    Puthen-Veettil, B., E-mail: b.puthen-veettil@unsw.edu.au; Patterson, R.; König, D.; Conibeer, G.; Green, M. A. [Australian Centre for Advanced Photovoltaics, UNSW, Sydney 2052 (Australia)

    2014-10-28T23:59:59.000Z

    Efficient iso-entropic energy filtering of electronic waves can be realized through nanostructures with three dimensional confinement, such as quantum dot resonant tunneling structures. Large-area deployment of such structures is useful for energy selective contacts but such configuration is susceptible to structural disorders. In this work, the transport properties of quantum-dot-based wide-area resonant tunneling structures, subject to realistic disorder mechanisms, are studied. Positional variations of the quantum dots are shown to reduce the resonant transmission peaks while size variations in the device are shown to reduce as well as broaden the peaks. Increased quantum dot size distribution also results in a peak shift to lower energy which is attributed to large dots dominating transmission. A decrease in barrier thickness reduces the relative peak height while the overall transmission increases dramatically due to lower “series resistance.” While any shift away from ideality can be intuitively expected to reduce the resonance peak, quantification allows better understanding of the tolerances required for fabricating structures based on resonant tunneling phenomena/.

  6. Showcasing the research of quantum dot sensitized solar cells from Prof. J.J.Tian's and Prof. G.Z.Cao's lab,

    E-Print Network [OSTI]

    Cao, Guozhong

    . Introduction Quantum dot sensitized solar cells (QDSCs) can be regarded as a derivative of dye-sensitized solarShowcasing the research of quantum dot sensitized solar cells from Prof. J.J.Tian's and Prof. G cells A hierarchical structure of ZnO/TiO2 nanocable photoanode for quantum dot sensitized solar cells

  7. Large internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko, Gerald Hnig, Christian Kindel, Sven Rodt, Andr Strittmatter et al.

    E-Print Network [OSTI]

    Nabben, Reinhard

    Large internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko, Gerald Hönig, Christian transitions in wurtzite InGaN/GaN coupled quantum dot nanowire heterostructures with polarization internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko,a Gerald Hönig, Christian Kindel, Sven

  8. Absorption spectra of CdSe-ZnS core-shell quantum dots at high photon energies : experiment and modeling

    E-Print Network [OSTI]

    Ghosh, Sandip

    Absorption spectra of CdSe-ZnS core-shell quantum dots at high photon energies : experiment spectra of CdSe-ZnS core-shell quantum dot (QD) ensembles, with average core diameters ranging from 2.6 nm. In agreement with previous reports, the absorption coefficient at energies 1 eV above the effective bandgap

  9. Excitonic properties of strained wurtzite and zinc-blende GaNAlxGa1xN quantum dots

    E-Print Network [OSTI]

    Fonoberov, Vladimir

    Excitonic properties of strained wurtzite and zinc-blende GaNÕAlxGa1ÀxN quantum dots Vladimir A 2003 We investigate exciton states theoretically in strained GaN/AlN quantum dots with wurtzite WZ of GaN QDs.1­8 Molecu- lar beam epitaxial growth in the Stranski­Krastanov mode of wurtzite WZ Ga

  10. Optical properties of wurtzite and zinc-blende GaNAlN quantum dots Vladimir A. Fonoberova)

    E-Print Network [OSTI]

    Fonoberov, Vladimir

    Optical properties of wurtzite and zinc-blende GaNÕAlN quantum dots Vladimir A. Fonoberova; published 20 August 2004 We investigate theoretically and compare optical properties of wurtzite and zincN/AlN interface governs optical properties of wurtzite quantum dots while having a small effect on zinc

  11. Getting Informations of Wavefunctions in Quantum Dots from the Fano Effect Shingo KATSUMOTO, Hisashi AIKAWA, Kensuke KOBAYASHI and Yasuhiro IYE

    E-Print Network [OSTI]

    Iye, Yasuhiro

    by around Coulomb (resonant) peaks obeying the Breit-Wigner law. On the other hand, there appeared-phase Coulomb peaks" in quantum dots. KEYWORDS: quantum dot, Fano effect, phase shift, AB effect 1. Introduction of the phase shift just at the Coulomb peaks. This was soon turned out to be a kind of artifact due to the two

  12. Double-Dot Quantum Ratchet Driven by an Independently Biased Quantum Point Contact V. S. Khrapai,1,2

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    Double-Dot Quantum Ratchet Driven by an Independently Biased Quantum Point Contact V. S. Khrapai,1 of the two quantum dots. The results are interpreted in terms of a quantum ratchet phenomenon in a DQD possessing current be- cause of broken spatial symmetry, so-called ratchets, ap- pear in a variety

  13. Microsphere Light-Scattering Layer Assembled by ZnO Nanosheets for the Construction of High Efficiency (>5%) Quantum Dots

    E-Print Network [OSTI]

    Cao, Guozhong

    performance solar cells for sustainable energy sources to replace fossil fuels has become an urgent subject for CdS/CdSe quantum dot cosensitized solar cells (QDSCs) with a power conversion efficiency (PCE Efficiency (>5%) Quantum Dots Sensitized Solar Cells Jianjun Tian,*, Lili Lv, Xuyang Wang, Chengbin Fei

  14. SiGe quantum dot single-hole transistor fabricated by atomic force microscope nanolithography and silicon epitaxial-regrowth

    E-Print Network [OSTI]

    Rokhinson, Leonid

    SiGe quantum dot single-hole transistor fabricated by atomic force microscope nanolithography; published online 10 November 2006 A SiGe quantum dot single-hole transistor passivated by silicon epitaxial are reproducible, in sharp contrast with the noisy and irreproducible I-V characteristics of unpassivated SiGe

  15. Single-electron quantum dot in Si/SiGe with integrated charge sensing C. B. Simmons,a

    E-Print Network [OSTI]

    Coppersmith, Susan N.

    Single-electron quantum dot in Si/SiGe with integrated charge sensing C. B. Simmons,a Madhu that are important for quantum information processing. Si/SiGe is of interest for semiconductor spin qubits and measurement of a top-gated quantum dot occupied by a single electron in a Si/SiGe heterostructure. Transport

  16. Monolithic phosphor-free InGaN/GaN quantum dot wavelength converter white light emitting diodes

    SciTech Connect (OSTI)

    Jahangir, Shafat; Bhattacharya, Pallab, E-mail: pkb@eecs.umich.edu [Center for Photonics and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States); Pietzonka, Ines; Strassburg, Martin [OSRAM Opto Semiconductors GmbH, Leibnizstrasse 4, Regensburg (Germany)

    2014-09-15T23:59:59.000Z

    We report the characteristics of phosphor-free self-organized InGaN/GaN quantum dot wavelength converter white light emitting diodes grown by plasma assisted molecular beam epitaxy. The exciting quantum dots, in which electrically injected carriers recombine, are blue-emitting and the converter dots are red-emitting. We have studied the effect of tuning the number of dot layers and the peak emission wavelength of the exciting and converter dots on the nature of the emitted white light, in terms of the chromaticity coordinates and correlated color temperature. Depending on the values of these wavelengths, color temperatures in the range of 4420–6700?K have been derived at a current density of 45?A/cm{sup 2} across multiple devices. The variation of the color temperature with change in injection current is found to be very small.

  17. Investigation of steady-state and time-dependent luminescence properties of colloidal InGaP quantum dots

    E-Print Network [OSTI]

    Chatterjee, Subhasish; Menon, Vinod M

    2012-01-01T23:59:59.000Z

    Quantum dots play a promising role in the development of novel optical and biosensing devices. In this study, we investigated steady-state and time-dependent luminescence properties of InGaP/ZnS core/shell colloidal quantum dots in a solution phase at room temperature. The steady state experiments exhibited an emission maximum at 650 nm with full width at half maximum of ~ 85 nm, and strong first-excitonic absorption peak at 600 nm. The time-resolved luminescence measurements depicted a bi-exponential decay profile with lifetimes of {\\tau}1\\sim 47 ns and {\\tau} 2\\sim 142 ns at the emission maximum. Additionally, luminescence quenching and lifetime reduction due to resonance energy transfer between the quantum dot and an absorber are demonstrated. Our results support the plausibility of using these InGaP quantum dots as an effective alternative to highly toxic conventional Cd or Pb based colloidal quantum dots for biological applications.

  18. Mn solid solutions in self-assembled Ge/Si (001) quantum dot heterostructures

    SciTech Connect (OSTI)

    Kassim, J.; Nolph, C.; Reinke, P.; Floro, J. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Jamet, M. [Institut Nanosciences et Cryogenie/SP2M, CEA-UJF, F-38054 Grenoble (France)

    2012-12-10T23:59:59.000Z

    Heteroepitaxial Ge{sub 0.98}Mn{sub 0.02} quantum dots (QDs) on Si (001) were grown by molecular beam epitaxy. The standard Ge wetting layer-hut-dome-superdome sequence was observed, with no indicators of second phase formation in the surface morphology. We show that Mn forms a dilute solid solution in the Ge quantum dot layer, and a significant fraction of the Mn partitions into a sparse array of buried, Mn-enriched silicide precipitates directly underneath a fraction of the Ge superdomes. The magnetic response from the ultra-thin film indicates the absence of robust room temperature ferromagnetism, perhaps due to anomalous intermixing of Si into the Ge quantum dots.

  19. Design of quantum dot lattices in amorphous matrices by ion beam irradiation

    SciTech Connect (OSTI)

    Buljan, M.; Bogdanovic-Radovic, I.; Karlusic, M.; Desnica, U. V.; Radic, N.; Jaksic, M.; Salamon, K.; Drazic, G.; Bernstorff, S.; Holy, V. [Rudjer Boskovic Institute, Bijenicka cesta 54, HR-10000 Zagreb (Croatia); Institute of Physics, Bijenicka cesta 46, HR-10000 Zagreb (Croatia); Jozef Stefan Institute, Jamova 39, SLO-1000 Ljubljana (Slovenia); Sincrotrone Trieste, I-34149 Basovizza (Italy); Charles University in Prague, CZ-12116 Prague (Czech Republic)

    2011-10-15T23:59:59.000Z

    We report on the highly controllable self-assembly of semiconductor quantum dots and metallic nanoparticles in a solid amorphous matrix, induced by ion beam irradiation of an amorphous multilayer. We demonstrate experimentally and theoretically a possibility to tune the basic structural properties of the quantum dots in a wide range. Furthermore, the sizes, distances, and arrangement type of the quantum dots follow simple equations dependent on the irradiation and the multilayer properties. We present a Monte Carlo model for the simulation and prediction of the structural properties of the materials formed by this method. The presented results enable engineering and simple production of functional materials or simple devices interesting for applications in nanotechnology.

  20. High-brightness single photon source from a quantum dot in a directional-emission nanocavity

    E-Print Network [OSTI]

    Mitsuru Toishi; Dirk Englund; Andrei Faraon; Jelena Vuckovic

    2009-04-08T23:59:59.000Z

    We analyze a single photon source consisting of an InAs quantum dot coupled to a directional-emission photonic crystal (PC) cavity implemented in GaAs. On resonance, the dot's lifetime is reduced by more than 10 times, to 45ps. Compared to the standard three-hole defect cavity, the perturbed PC cavity design improves the collection efficiency into an objective lens (NA=0.75) by factor 6, and improves the coupling efficiency of the collected light into a single mode fiber by factor 1.9. The emission frequency is determined by the cavity mode, which is antibunched to g(2)=0.05. The cavity design also enables efficient coupling to a higher-order cavity mode for local optical excitation of cavity-coupled quantum dots.

  1. Nuclear Spin Dynamics in Double Quantum Dots: Multi-Stability, Dynamical Polarization, Criticality and Entanglement

    E-Print Network [OSTI]

    Martin J. A. Schuetz; Eric M. Kessler; Lieven M. K. Vandersypen; J. Ignacio Cirac; Geza Giedke

    2014-05-30T23:59:59.000Z

    We theoretically study the nuclear spin dynamics driven by electron transport and hyperfine interaction in an electrically-defined double quantum dot (DQD) in the Pauli-blockade regime. We derive a master-equation-based framework and show that the coupled electron-nuclear system displays an instability towards the buildup of large nuclear spin polarization gradients in the two quantum dots. In the presence of such inhomogeneous magnetic fields, a quantum interference effect in the collective hyperfine coupling results in sizable nuclear spin entanglement between the two quantum dots in the steady state of the evolution. We investigate this effect using analytical and numerical techniques, and demonstrate its robustness under various types of imperfections.

  2. Photoinduced band filling in strongly confined colloidal PbS quantum dots

    SciTech Connect (OSTI)

    Ullrich, B., E-mail: bruno@fis.unam.mx [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210 (Mexico); Ullrich Photonics LLC, Wayne, Ohio 43466 (United States); Xi, H. [Department of Physics and Astronomy, Bowling Green State University, Bowling Green, Ohio 43403-0209 (United States); Wang, J. S. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson AFB, Ohio 45433-7707 (United States)

    2014-06-21T23:59:59.000Z

    Increase in continuous wave laser excitation (6?W/cm{sup 2} to 120?W/cm{sup 2}) of colloidal PbS quantum dots in the strongly quantized regime (diameters 2.0?nm and 4.7?nm) deposited on semi-insulating GaAs and glass causes a clear blue shift (0.019?eV and 0.080?eV) of the emission spectra. Proof of the applicability of a dynamic three-dimensional band filling model is the significance of the presented results and demonstrates the effective electronic coupling in quantum dot arrays similar to superlattices. The work also reveals the influence of quantum dot sizes on photo-doping effects.

  3. Distinctive Signature of Indium Gallium Nitride Quantum Dot Lasing in Microdisks Cavities

    E-Print Network [OSTI]

    Woolf, Alexander; Aharanovich, Igor; Zhu, Tongtong; Niu, Nan; Wang, Danqing; Oliver, Rachel A; Hu, Evelyn L

    2014-01-01T23:59:59.000Z

    Low threshold lasers realized within compact, high quality optical cavities enable a variety of nanophotonics applications. Gallium nitride (GaN) materials containing indium gallium nitride (InGaN) quantum dots and quantum wells offer an outstanding platform to study light matter interactions and realize practical devices such as efficient light emitting diodes and nanolasers. Despite progress in the growth and characterization of InGaN quantum dots, their advantages as the gain medium in low threshold lasers have not been clearly demonstrated. This work seeks to better understand the reasons for these limitations by focusing on the simpler, limited-mode microdisk cavities, and by carrying out comparisons of lasing dynamics in those cavities using varying gain media including InGaN quantum wells, fragmented quantum wells, and a combination of fragmented quantum wells with quantum dots. For each gain medium, we utilize the distinctive, high quality (Q~5500) modes of the cavities, and the change in the highest ...

  4. AUTHORIZING THE DOT SPECIFICATION 6M PACKAGING FOR CONTINUED USE AT THE SAVANNAH RIVER SITE

    SciTech Connect (OSTI)

    Watkins, R.; Loftin, B.; Hoang, D.

    2010-03-04T23:59:59.000Z

    The U.S. Department of Transportation (DOT) Specification 6M packaging was in extensive use for more than 40 years for in-commerce shipments of Type B quantities of fissile and radioactive material (RAM) across the USA, among the Department of Energy (DOE) laboratories, and between facilities in the DOE production complex. In January 2004, the DOT Research and Special Programs Administration (RSPA) Agency issued a final rule in the Federal Register to ammend requirements in the Hazardous Materials Regulations (HMR) pertaining to the transportation of radioactive materials. The final rule became effective on October 1, 2004. One of those changes discontinued the use of the DOT specification 6M, along with other DOT specification packagings, on October 1, 2008. A main driver for the change was due to the fact that 6M specification packagings were not supported by a Safety Analysis Report for Packagings (SARP) that was compliant with Title 10 of the Code of Federal Regulations (CFR) Part 71 (10 CFR 71). The regulatory rules for the discontinued use have been edited in Title 49 of the CFR Parts 100-185, 2004 edition and thereafter. Prior to October 1, 2008, the use of the 6M within the boundaries of the Savannah River Site (SRS), called an onsite transfer, was governed by an onsite transportation document that referenced 49 CFR Parts 100-185. SRS had to develop an Onsite Safety Assessment (OSA) which was independent of 49 CFR in order to justify the continued use of the DOT Specification 6M for the transfer of radioactive material (RAM) at the SRS after October 1, 2008. This paper will discuss the methodology for and difficulties associated with authorizing the DOT Specification 6M Packaging for continued use at the Savannah River Site.

  5. Energy levels of double triangular graphene quantum dots

    SciTech Connect (OSTI)

    Liang, F. X.; Jiang, Z. T., E-mail: ztjiang616@hotmail.com; Zhang, H. Y.; Li, S. [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Lv, Z. T. [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); School of Physical Science and Information Engineering, Liaocheng University, Liaocheng 252059 (China)

    2014-09-28T23:59:59.000Z

    We investigate theoretically the energy levels of the coupled double triangular graphene quantum dots (GQDs) based on the tight-binding Hamiltonian model. The double GQDs including the ZZ-type, ZA-type, and AA-type GQDs with the two GQDs having the zigzag or armchair boundaries can be coupled together via different interdot connections, such as the direct coupling, the chains of benzene rings, and those of carbon atoms. It is shown that the energy spectrum of the coupled double GQDs is the amalgamation of those spectra of the corresponding two isolated GQDs with the modification triggered by the interdot connections. The interdot connection is inclined to lift up the degeneracies of the energy levels in different degree, and as the connection changes from the direct coupling to the long chains, the removal of energy degeneracies is suppressed in ZZ-type and AA-type double GQDs, which indicates that the two coupled GQDs are inclined to become decoupled. Then we consider the influences on the spectra of the coupled double GQDs induced by the electric fields applied on the GQDs or the connection, which manifests as the global spectrum redistribution or the local energy level shift. Finally, we study the symmetrical and asymmetrical energy spectra of the double GQDs caused by the substrates supporting the two GQDs, clearly demonstrating how the substrates affect the double GQDs' spectrum. This research elucidates the energy spectra of the coupled double GQDs, as well as the mechanics of manipulating them by the electric field and the substrates, which would be a significant reference for designing GQD-based devices.

  6. Test and evaluation document for DOT Specification 7A Type A Packaging. Revision 3

    SciTech Connect (OSTI)

    NONE

    1996-01-30T23:59:59.000Z

    The US Department of Energy (DOE) has been conducting, through several of its operating contractors, an evaluation and testing program to qualify Type A radioactive material packagings per US Department of Transportation (DOT) Specification 7A (DOT-7A) of the Code of Federal Regulations (CFR), Title 49, Part 178 (49 CFR 178). The program is currently administered by the DOE, Office of Facility Safety Analysis, DOE/EH-32, at DOE-Headquarters (DOE-HQ) in Germantown, Maryland. This document summarizes the evaluation and testing performed for all of the packagings successfully qualified in this program.

  7. Growth and optical characterization of multilayers of InGaN quantum dots

    E-Print Network [OSTI]

    Zhu, Tontong; El-Ella, Haitham; Reid, Benjamin; Holmes, Mark; Taylor, Robert; Kappers, Menno; Oliver, Rachel

    2012-01-01T23:59:59.000Z

    carried out using a two photon excitation technique employing a picosecond mode-locked Ti-sapphire laser emitting at 790 nm. Samples were mounted in a cold -finger cryostat that could be cooled down to 4.2 K and the laser was focused through a microscope... GaN quantum dots Article Type: Research Paper Section/Category: General subjects Keywords: B2. InGaN quantum dots; A1. Photoluminescence; B1. Nitrides; A3. Metal-organic vapour phase epitaxy Corresponding Author: Dr Tongtong Zhu, Ph...

  8. Sub-microsecond correlations in photoluminescence from InAs quantum dots

    E-Print Network [OSTI]

    Charles Santori; David Fattal; Jelena Vuckovic; Glenn S. Solomon; Edo Waks; Yoshihisa Yamamoto

    2003-08-16T23:59:59.000Z

    Photon correlation measurements reveal memory effects in the optical emission of single InAs quantum dots with timescales from 10 to 800 ns. With above-band optical excitation, a long-timescale negative correlation (antibunching) is observed, while with quasi-resonant excitation, a positive correlation (blinking) is observed. A simple model based on long-lived charged states is presented that approximately explains the observed behavior, providing insight into the excitation process. Such memory effects can limit the internal efficiency of light emitters based on single quantum dots, and could also be problematic for proposed quantum-computation schemes.

  9. An Efficient Source of Single Photons: A Single Quantum Dot in a Micropost Microcavity

    E-Print Network [OSTI]

    Matthew Pelton; Charles Santori; Jelena Vuckovic; Bingyang Zhang; Glenn S. Solomon; Jocelyn Plant; Yoshihisa Yamamoto

    2002-08-08T23:59:59.000Z

    We have demonstrated efficient production of triggered single photons by coupling a single semiconductor quantum dot to a three-dimensionally confined optical mode in a micropost microcavity. The efficiency of emitting single photons into a single-mode travelling wave is approximately 38%, which is nearly two orders of magnitude higher than for a quantum dot in bulk semiconductor material. At the same time, the probability of having more than one photon in a given pulse is reduced by a factor of seven as compared to light with Poissonian photon statistics.

  10. Cavity Quantum Electrodynamics with a Single Quantum Dot Coupled to a Photonic Molecule

    E-Print Network [OSTI]

    Arka Majumdar; Armand Rundquist; Michal Bajcsy; Jelena Vu?kovi?

    2012-01-30T23:59:59.000Z

    We demonstrate the effects of cavity quantum electrodynamics for a quantum dot coupled to a photonic molecule, consisting of a pair of coupled photonic crystal cavities. We show anti-crossing between the quantum dot and the two super-modes of the photonic molecule, signifying achievement of the strong coupling regime. From the anti-crossing data, we estimate the contributions of both mode-coupling and intrinsic detuning to the total detuning between the super-modes. Finally, we also show signatures of off-resonant cavity-cavity interaction in the photonic molecule.

  11. Fast Electrical Control of a Quantum Dot Strongly Coupled to a Nano-resonator

    E-Print Network [OSTI]

    Andrei Faraon; Arka Majumdar; Hyochul Kim; Pierre Petroff; Jelena Vuckovic

    2009-06-03T23:59:59.000Z

    The resonance frequency of an InAs quantum dot strongly coupled to a GaAs photonic crystal cavity was electrically controlled via quantum confined Stark effect. Stark shifts up to 0.3meV were achieved using a lateral Schottky electrode that created a local depletion region at the location of the quantum dot. We report switching of a probe laser coherently coupled to the cavity up to speeds as high as 150MHz, limited by the RC constant of the transmission line. The coupling rate and the magnitude of the Stark shift with electric field were investigated while coherently probing the system.

  12. Temperature dependency of the emission properties from positioned In(Ga)As/GaAs quantum dots

    SciTech Connect (OSTI)

    Braun, T.; Schneider, C.; Maier, S.; Forchel, A.; Höfling, S.; Kamp, M. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074, Würzburg (Germany); Igusa, R.; Iwamoto, S.; Arakawa, Y. [University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2014-09-15T23:59:59.000Z

    In this letter we study the influence of temperature and excitation power on the emission linewidth from site-controlled InGaAs/GaAs quantum dots grown on nanoholes defined by electron beam lithography and wet chemical etching. We identify thermal electron activation as well as direct exciton loss as the dominant intensity quenching channels. Additionally, we carefully analyze the effects of optical and acoustic phonons as well as close-by defects on the emission linewidth by means of temperature and power dependent micro-photoluminescence on single quantum dots with large pitches.

  13. Noise-Protected Gate for Six-Electron Double-Dot Qubits

    E-Print Network [OSTI]

    Sebastian Mehl; David P. DiVincenzo

    2014-08-05T23:59:59.000Z

    Singlet-triplet spin qubits in six-electron double quantum dots, in moderate magnetic fields, can show superior immunity to charge noise. This immunity results from the symmetry of orbitals in the second energy shell of circular quantum dots: singlet and triplet states in this shell have identical charge distributions. Our phase-gate simulations, which include $1/f$ charge noise from fluctuating traps, show that this symmetry is most effectively exploited if the gate operation switches rapidly between sweet spots deep in the (3,3) and (4,2) charge stability regions; fidelities very close to one are predicted if subnanosecond switching can be performed.

  14. Controlling the nuclear polarization in quantum dots using optical pulses with a modest bandwidth

    E-Print Network [OSTI]

    S. G. Carter; Sophia E. Economou; A. Shabaev; A. S. Bracker

    2011-02-02T23:59:59.000Z

    We show that detuned optical pulse trains with a modest spectral width can polarize nuclear spins in InAs quantum dots. The pulse bandwidth is large enough to excite a coherent superposition of both electron spin eigenstates in these negatively charged dots but narrow enough to give partial spectral selectivity between the eigenstates. The coherent precession of electron spin states and periodic excitation focuses the nuclear spin distribution, producing a discrete set of precession modes. The spectral selectivity generates a net nuclear polarization, through a mechanism that relies on optical spin rotations rather than electron spin relaxation.

  15. Investigation of quantum confinement behavior of zinc sulphide quantum dots synthesized via various chemical methods

    SciTech Connect (OSTI)

    Jose, Meera, E-mail: gunasekaran@karunya.edu; Sakthivel, T., E-mail: gunasekaran@karunya.edu; Chandran, Hrisheekesh T., E-mail: gunasekaran@karunya.edu; Nivea, R., E-mail: gunasekaran@karunya.edu; Gunasekaran, V., E-mail: gunasekaran@karunya.edu [Nanomaterials Research Lab, Department of Nanoscience and Technology, Karunya University, Coimbatore - 641 114, Tamil Nadu (India)

    2014-10-15T23:59:59.000Z

    In this work, undoped and Ag-doped ZnS quantum dots were synthesized using various chemical methods. The products were characterized using X-ray diffraction (XRD), UV-visible spectroscopy and Photoluminescence spectroscopy. Our results revealed that the size of the as-prepared samples range from 1–6 nm in diameter and have a cubic zinc-blende structure. Also, we observed the emission of different wavelength of light from different sized quantum dots of the same material due to quantum confinement effect. The results will be presented in detail and ZnS can be a potential candidate for optical device development and applications.

  16. Photo-induced conductance fluctuations in mesoscopic Ge/Si systems with quantum dots

    SciTech Connect (OSTI)

    Stepina, N. P.; Dvurechenskii, A. V.; Nikiforov, A. I. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation); Moers, J.; Gruetzmacher, D. [Institute of Bio- and Nanosystems, Forschungszentrum Julich GmbH 52425 Julich (Germany)

    2014-08-20T23:59:59.000Z

    We study the evolution of electron transport in strongly localized mesoscopic system with quantum dots under small photon flux. Exploring devices with narrow transport channels lead to the observation of giant fluctuations of the photoconductance, which is attributed to the strong dependence of hopping current on the filling of dots by holes. In our experiments, single-photon mode operation is indicated by the linear dependence of the frequency of photo-induced fluctuations on the light intensity and the step-like response of conductance on the pulse excitation. The effect of the light wavelength, measurement temperature, size of the conductive channel on the device efficiency are considered.

  17. A finite element analysis of a silicon based double quantum dot structure

    E-Print Network [OSTI]

    S. Rahman; J. Gorman; C. H. W. Barnes; D. A. Williams; H. P. Langtangen

    2006-04-06T23:59:59.000Z

    We present the results of a finite-element solution of the Laplace equation for the silicon-based trench-isolated double quantum-dot and the capacitively-coupled single-electron transistor device architecture. This system is a candidate for charge and spin-based quantum computation in the solid state, as demonstrated by recent coherent-charge oscillation experiments. Our key findings demonstrate control of the electric potential and electric field in the vicinity of the double quantum-dot by the electric potential applied to the in-plane gates. This constitutes a useful theoretical analysis of the silicon-based architecture for quantum information processing applications.

  18. Photoluminescence from In0.5Ga0.5As/GaP quantum dots coupled to photonic crystal cavities

    E-Print Network [OSTI]

    Kelley Rivoire; Sonia Buckley; Yuncheng Song; Minjoo Larry Lee; Jelena Vuckovic

    2012-01-05T23:59:59.000Z

    We demonstrate room temperature visible wavelength photoluminescence from In0.5Ga0.5As quantum dots embedded in a GaP membrane. Time-resolved above band photoluminescence measurements of quantum dot emission show a biexpontential decay with lifetimes of ~200 ps. We fabricate photonic crystal cavities which provide enhanced outcoupling of quantum dot emission, allowing the observation of narrow lines indicative of single quantum dot emission. This materials system is compatible with monolithic integration on Si, and is promising for high efficiency detection of single quantum dot emission as well as optoelectronic devices emitting at visible wavelengths.

  19. Cryogenic spectroscopy of ultra-low density colloidal lead chalcogenide quantum dots on chip-scale optical cavities towards single quantum dot near-infrared cavity QED

    E-Print Network [OSTI]

    Ranojoy Bose; Jie Gao; James F. McMillan; Alex D. Williams; Chee Wei Wong

    2009-11-09T23:59:59.000Z

    We present evidence of cavity quantum electrodynamics from a sparse density of strongly quantum-confined Pb-chalcogenide nanocrystals (between 1 and 10) approaching single-dot levels on moderately high-Q mesoscopic silicon optical cavities. Operating at important near-infrared (1500-nm) wavelengths, large enhancements are observed from devices and strong modifications of the QD emission are achieved. Saturation spectroscopy of coupled QDs is observed at 77K, highlighting the modified nanocrystal dynamics for quantum information processing.

  20. Intermediate-band solar cells based on quantum dot supracrystals Q. Shao and A. A. Balandina

    E-Print Network [OSTI]

    parameter in the photovoltaic PV solar cell technology. It is defined as = FFVocJsc Pin , 1 where FFIntermediate-band solar cells based on quantum dot supracrystals Q. Shao and A. A. Balandina Nano to implement the intermediate-band solar cell with the efficiency exceeding the Shockley-Queisser limit

  1. A Surface Plasmon Enhanced Infrared Photodetector Based on InAs Quantum Dots

    E-Print Network [OSTI]

    Krishna, Sanjay

    A Surface Plasmon Enhanced Infrared Photodetector Based on InAs Quantum Dots Chun-Chieh Chang-QD photodetector can facilitate a strong plasmonic-QD interaction, leading to a 130% absolute enhancement of infrared photoresponse at the plasmonic resonance. Our study indicates two key mechanisms

  2. Distance-Engineered Plasmon-Enhanced Light Harvesting in CdSe Quantum Dots

    E-Print Network [OSTI]

    Distance-Engineered Plasmon-Enhanced Light Harvesting in CdSe Quantum Dots Shengye Jin,,§, Erica De) is essential for the development of efficient QD-based solar energy conversion systems. In this study, plasmon as a function of interparticle (QD to Ag NP) distance. Up to 24-fold plasmonic enhancement of fluorescence from

  3. Infrared and photoluminescence spectroscopy of p-doped self-assembled Ge dots on Si

    E-Print Network [OSTI]

    Rokhinson, Leonid

    Infrared and photoluminescence spectroscopy of p-doped self-assembled Ge dots on Si L. P Received 14 June 1999; accepted for publication 17 August 1999 We report infrared photocurrent PC-8 Quantum well infrared photodetector QWIP technol- ogy has matured rapidly in the last several years.1

  4. Growth of a single freestanding multiwall carbon nanotube on each nanonickel dot

    E-Print Network [OSTI]

    Reed, Mark

    that the structures are indeed hollow nanotubes. The diameter and height depend on the nickel dot size and growth time displays FEDs . Attempts to manipulate nano- tubes for these applications have been made by postgrowth deposition CVD on mesopo- rous silica with imbedded iron particles.9 The growth of large arrays of well

  5. Spin States in Graphene Quantum Dots J. Guttinger,* T. Frey, C. Stampfer,

    E-Print Network [OSTI]

    Ihn, Thomas

    is connected via tunneling constrictions to source (s) and drain (d) contacts. It is tunable by the back gate with a base tempera- ture of 90 mK. The source-drain conductance of the device measured over a large back gate) Quantum dot source-drain con- ductance for varying back gate voltage (Vb ¼ 100 V). (b) Coulomb diamond

  6. Fine Structure of Highly Charged Excitons in Semiconductor Quantum Dots B. Urbaszek,1

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    quantum dots (QDs) are artificial atoms whose properties can be individually measured in their solid, the degeneracy of the excitonic ground state is lifted by the electron-hole (EH) exchange interaction, resultingV, they can be much larger in semiconductor nanocrystals [3] or polymers [4]. In all these systems

  7. Targeting quantum dots to surface proteins in living cells with biotin ligase

    E-Print Network [OSTI]

    coli biotin ligase site-specifically biotinylates a lysine side chain within a 15-amino acid acceptor molecule Quantum dots (QDs) are semiconductor nanoparticles that greatly expand the possibilities target the functional groups of one protein amidst all of the other expressed proteins containing

  8. Theoretical performance of solar cell based on mini-bands quantum dots

    SciTech Connect (OSTI)

    Aly, Abou El-Maaty M., E-mail: drabouelmaaty@hotmail.com, E-mail: ashraf.nasr@gmail.com [Power Electronics and Energy Conversion Department, ERI, NRCB (Egypt); College of Computer, Qassim University, P.O.B. 6688, Buryadah 51453 (Saudi Arabia); Nasr, A., E-mail: drabouelmaaty@hotmail.com, E-mail: ashraf.nasr@gmail.com [Radiation Engineering Department, NCRRT, Atomic Energy Authority (Egypt); College of Computer, Qassim University, P.O.B. 6688, Buryadah 51453 (Saudi Arabia)

    2014-03-21T23:59:59.000Z

    The tremendous amount of research in solar energy is directed toward intermediate band solar cell for its advantages compared with the conventional solar cell. The latter has lower efficiency because the photons have lower energy than the bandgap energy and cannot excite mobile carriers from the valence band to the conduction band. On the other hand, if mini intermediate band is introduced between the valence and conduction bands, then the smaller energy photons can be used to promote charge carriers transfer to the conduction band and thereby the total current increases while maintaining a large open circuit voltage. In this article, the influence of the new band on the power conversion efficiency for structure of quantum dots intermediate band solar cell is theoretically investigated and studied. The time-independent Schrödinger equation is used to determine the optimum width and location of the intermediate band. Accordingly, achievement of a maximum efficiency by changing the width of quantum dots and barrier distances is studied. Theoretical determination of the power conversion efficiency under the two different ranges of QD width is presented. From the obtained results, the maximum power conversion efficiency is about 70.42%. It is carried out for simple cubic quantum dot crystal under fully concentrated light. It is strongly dependent on the width of quantum dots and barrier distances.

  9. Photovoltaic nanopillar radial junction diode architecture enhanced by integrating semiconductor quantum dot nanocrystals as light harvesters

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    Photovoltaic nanopillar radial junction diode architecture enhanced by integrating semiconductor hybridized, radial p-n junction based, nanopillar solar cells with photovoltaic performance enhanced. By furnishing Si based nanopillar photovoltaic diodes with CdSe quantum dots, we experimentally showed up

  10. Cu2ZnSnS4 nanocrystals and graphene quantum dots for photovoltaics Xukai Xinab

    E-Print Network [OSTI]

    Lin, Zhiqun

    Cu2ZnSnS4 nanocrystals and graphene quantum dots for photovoltaics Jun Wang,a Xukai Xinab advances in the synthesis and utilization of CZTS nanocrystals and colloidal GQDs for photovoltaics emerged to achieve low cost, high perfor- mance photovoltaics, including organic solar cells,2­6 dye

  11. Single pulse ultrafast laser imprinting of axial dot arrays in bulk glasses C. Mauclair,1,

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Single pulse ultrafast laser imprinting of axial dot arrays in bulk glasses C. Mauclair,1, A sam- ples were irradiated with 160 fs pulses from an 800 nm Ti:Sapphire amplified ultrafast laser.mauclair@univ-st-etienne.fr Compiled December 20, 2010 Ultrafast laser processing of bulk transparent materials can significantly gain

  12. Synthesis and optical properties of cadmium selenide quantum dots for white light-emitting diode application

    SciTech Connect (OSTI)

    Xu, Xianmei; Wang, Yilin; Gule, Teri; Luo, Qiang [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Zhou, Liya, E-mail: zhouliyatf@163.com [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Gong, Fuzhong [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China)

    2013-03-15T23:59:59.000Z

    Highlights: ? Stable CdSe QDs were synthesized by the one-step and two-level process respectively. ? The fabricated white LEDs show good white balance. ? CdSe QDs present well green to yellow band luminescence. ? CdSe QDs displayed a broad excitation band. - Abstract: Yellow light-emitting cadmium selenide quantum dots were synthesized using one-step and two-step methods in an aqueous medium. The structural luminescent properties of these quantum dots were investigated. The obtained cadmium selenide quantum dots displayed a broad excitation band suitable for blue or near-ultraviolet light-emitting diode applications. White light-emitting diodes were fabricated by coating the cadmium selenide samples onto a 460 nm-emitting indium gallium nitrite chip. Both samples exhibited good white balance. Under a 20 mA working current, the white light-emitting diode fabricated via the one-step and two-step methods showed Commission Internationale de l’Éclairage coordinates at (0.27, 0.23) and (0.27, 0.33), respectively, and a color rendering index equal to 41 and 37, respectively. The one-step approach was simpler, greener, and more effective than the two-step approach. The one-step approach can be enhanced by combining cadmium selenide quantum dots with proper phosphors.

  13. Coupling an electron spin in a semiconductor quantum dot to an optical nano-cavity

    E-Print Network [OSTI]

    Arka Majumdar; Per Kaer; Michal Bajcsy; Erik D. Kim; Konstantinos G. Lagoudakis; Armand Rundquist; Jelena Vuckovic

    2013-04-07T23:59:59.000Z

    We propose a scheme to efficiently couple a single quantum dot electron spin to an optical nano-cavity, which enables us to simultaneously benefit from a cavity as an efficient photonic interface, as well as to perform high fidelity (nearly 100%) spin initialization and manipulation achievable in bulk semiconductors. Moreover, the presence of the cavity speeds up the spin initialization process beyond GHz.

  14. Influence of pair coherence on charge tunneling through a quantum dot connected to a superconducting lead

    E-Print Network [OSTI]

    Domanski, Tadeusz

    Influence of pair coherence on charge tunneling through a quantum dot connected the temperature below T* larger than Tc the single particle states become gradually depleted over a certain energy to a close neighborhood to the Mott insulating state, or because of competition with some other types

  15. Magnetic domain structure and magnetization reversal in submicron-scale Co dots

    SciTech Connect (OSTI)

    Fernandez, A., LLNL

    1998-02-17T23:59:59.000Z

    We present a magnetic force microscopy (MFM) analysis of arrays of submicron-scale Co dots fabricated by interference lithography. The dots are thin (180-300 A) and are elliptical in shape. MFM of these structures reveals that they relax into highly ordered remanent states whose symmetry and configuration are governed by their shape anisotropy. In particular, when the dots are saturated along the easy-axis, a uniformly magnetized state persists at remanence. However, when the dots are saturated in hard-axis, they relax into a single-vortex state in which the circulation can have either sign. Both remanent states are characterized by smoothly varying magnetization patterns and a high degree of uniformity across the array. We attribute the ordered behavior of these structures to the film microstructure, which allows the shape anisotropy to dominate over magnetocrystalline anisotropy. By imaging a series of minor-loop remanent states, we show that magnetization reversal in these structures occurs via the nucleation and annihilation of a single vortex. Magnetic hysteresis loop measurements are consistent with these observations and provide additional details. Furthermore, we present the results of micromagnetic simulations, which are in excellent agreement with both the MFM images and the hysteresis loop measurements.

  16. Effect of the (OH) Surface Capping on ZnO Quantum Dots

    E-Print Network [OSTI]

    Nabben, Reinhard

    in air at different temperatures from 150­500 C for 30 min. In comparison, highly purified bulk Zn is related to oxygen deficiency [1]; the other is a much narrower ultraviolet (UV) emission band at around, compared with good quality ZnO single crystals or ZnO powders, the UV bandgap luminescence in quantum dots

  17. Enhanced quantum dot optical down-conversion using asymmetric 2D photonic crystals

    E-Print Network [OSTI]

    Cunningham, Brian

    -performance crosslinked colloidal quantum-dot light-emitting diodes," Nat. Photonics 3(6), 341­345 (2009). 10. D. Englund. Medvedev, M. Kazes, S. H. Kan, and U. Banin, "Efficient near-infrared polymer nanocrystal light- emitting diodes," Science 295(5559), 1506­1508 (2002). 8. V. Wood, M. J. Panzer, J. L. Chen, M. S. Bradley, J. E

  18. Electronic structure of wurtzite quantum dots with cylindrical symmetry L. C. Lew Yan Voona

    E-Print Network [OSTI]

    Melnik, Roderick

    Electronic structure of wurtzite quantum dots with cylindrical symmetry L. C. Lew Yan Voona July 2005 This paper presents a six-band k·p theory for wurtzite semiconductor nanostructures to the Rashba-Sheka-Pikus Hamiltonian for wurtzite semiconductors, without the need for the axial approximation

  19. Single hole quantum dot transistors in silicon Effendi Leobandung, Lingjie Guo, and Stephen Y. Choua)

    E-Print Network [OSTI]

    of the gate voltage have been observed at temperatures over 81 K and drain biases over 66 mV. The oscillations to the drain. As the gate voltage was scanned, the drain current i.e., the hole current oscil- lated Fig. 3-dot transistors were fabricated in silicon-on-insulator. Strong oscillations in the drain current as a function

  20. Wave-Function Mapping of Graphene Quantum Dots with Soft Confinement D. Subramaniam,1

    E-Print Network [OSTI]

    Florian, Libisch

    Wave-Function Mapping of Graphene Quantum Dots with Soft Confinement D. Subramaniam,1 F. Libisch,2) Using low-temperature scanning tunneling spectroscopy, we map the local density of states of graphene the graphene K point, the electronic properties of the QDs are dominantly graphenelike. Indeed, we compare

  1. Whispering-Gallery Modes in Quantum Dot Embedded Microspheres for Sensing Applications

    E-Print Network [OSTI]

    Beier, Hope T.

    2011-02-22T23:59:59.000Z

    that shift position with variations in the local index of refraction sampled by the evanescent tail of the WGMs. To excite these WGMs, we embed quantum dots (QDs) in the periphery of polystyrene microspheres to serve as local light sources. By coupling...

  2. Role of Symmetry Breaking on the Optical Transitions in Lead-Salt Quantum Dots

    E-Print Network [OSTI]

    Van Stryland, Eric

    Role of Symmetry Breaking on the Optical Transitions in Lead-Salt Quantum Dots Gero Nootz to explain optical transitions in lead-salt QDs. Thus, while the band anisotropy of the bulk semiconductor functions. These studies clarify the controversy of the origin of spectral features in lead-salt QDs

  3. Towards a feasible implementation of quantum neural networks using quantum dots

    E-Print Network [OSTI]

    M. V. Altaisky; N. N. Zolnikova; N. E. Kaputkina; V. A. Krylov; Yu. E. Lozovik; N. S. Dattani

    2015-03-17T23:59:59.000Z

    We propose an implementation of quantum neural networks using an array of single-electron quantum dots with dipole-dipole interactions. We demonstrate that this implementation is both feasible and versatile by studying it within the framework of GaAs based quantum dot qubits coupled to a reservoir of acoustic phonons; a system whose decoherence properties have been experimentally and theoretically characterized with meticulous detail, and is considered one of the most accurately understood open quantum systems. Using numerically exact Feynman integral calculations, we have found that the quantum coherence in our neural networks survive for several ns even at liquid nitrogen temperatures (77 K), which is three orders of magnitude higher than current implementations which are based on SQUIDs operating at temperatures in the mK range. Furthermore, the previous quantum dot based proposals required control via manipulating the phonon bath, which is extremely difficult in real experiments. An advantage of our implementation is that it can be easily controlled, since dipole-dipole interaction strengths can be changed via the spacing between the dots and applying external fields.

  4. Warm-white light-emitting diodes integrated with colloidal quantum dots for high luminous

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    Warm-white light-emitting diodes integrated with colloidal quantum dots for high luminous efficacy NQD-LED design with both high luminous efficacy of optical radiation and CRI is presented to have luminous efficacy of optical ra- diation (LER), which is challenging using conventional phosphors

  5. Accurate determination of energy scales in few-electron double quantum dots D. Taubert,1

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    methods to determine the gate voltage to energy conversion accurately in the different regimes of dot-lead tunnel couplings and demonstrate strong variations of the conversion factors. Our concepts can easily involves a conversion of the applied gate voltages to energy differences between the electronic states

  6. Depleted-heterojunction colloidal quantum dot photovoltaics employing low-cost electrical contacts

    E-Print Network [OSTI]

    Department of Materials Science and Engineering, 184 College Street, Toronto, Ontario M5S 3E4, Canada 3 of depleted-heterojunction colloidal quantum dot solar cells, we describe herein a strategy that replaces. © 2010 American Institute of Physics. doi:10.1063/1.3463037 Solar energy harvesting requires

  7. Prospective Article Materials processing strategies for colloidal quantum dot solar cells

    E-Print Network [OSTI]

    energy sources, particularly with cheap and plentiful natural gas, solar photovoltaic systems must cost of the solar panels themselves. Third-generation photovoltaic systems, including organic, dye-sensitized, and colloidal quantum dot (CQD) solar cells, offer a path to low-weight, low-cost, and prospectively high

  8. PHYSICAL REVIEW B 85, 085117 (2012) Spin thermopower in interacting quantum dots

    E-Print Network [OSTI]

    Ramsak, Anton

    2012-01-01T23:59:59.000Z

    renormalization group method, we investigate the spin thermopower of a quantum dot in a magnetic field, the dependence of the spin-Seebeck coefficient on the temperature and the magnetic field is explained in terms applications, including power generation, refrigeration, and temperature measurement.1 Thermoelectric phenomena

  9. GaN/AlN Quantum Wells and Quantum Dots for Unipolar Devices at Telecommunication Wavelengths

    SciTech Connect (OSTI)

    Julien, Francois H.; Tchernycheva, Maria; Doyennette, Laetitia; Nevou, Laurent; Lupu, Anatole; Warde, Elias [Institut d'Electronique Fondamentale, Universite Paris Sud, UMR 8622 CNRS, 91405 Orsay (France); Guillot, Fabien; Monroy, Eva; Bellet-Amalric, Edith [Equipe mixte CEACNRS-UJF, DRFMC/SP2M/PSC, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble (France); Vardi, Alon; Bahir, Gad [Departement of Electrical Engineering, Technion-Israel Institute of Technology, Haifa 3200 (Israel)

    2007-04-10T23:59:59.000Z

    We report on the latest achievements in terms of growth and optical investigation of ultrathin GaN/AlN isolated and coupled quantum wells grown by plasma-assisted molecular-beam epitaxy. We also present the observation of intraband absorption in self-organized GaN quantum dots and on the application to infrared photodetection at telecommunication wavelengths.

  10. Study of the self-organization processes in lead sulfide quantum dots

    SciTech Connect (OSTI)

    Tarasov, S. A., E-mail: SATarasov@mail.ru; Aleksandrova, O. A.; Maksimov, A. I.; Maraeva, E. V.; Matyushkin, L. B.; Men’kovich, E. A.; Moshnikov, V. A. [St. Petersburg Electrotechnical University LETI (Russian Federation); Musikhin, S. F. [St. Petersburg State Polytechnic University (Russian Federation)

    2014-12-15T23:59:59.000Z

    A procedure is described for the synthesis of nanoparticles based on lead chalcogenides. The procedure combines the synthesis of colloidal quantum dots (QDs) in aqueous solutions with simultaneous organization of the QDs into ordered arrays. The processes of the self-organization of QDs are analyzed at the nano- and microscopic levels by the photoluminescence method, atomic-force microscopy, and optical microscopy.

  11. Detecting quantum-coherent nanomechanical oscillations using the current-noise spectrum of a double quantum dot

    E-Print Network [OSTI]

    Neill Lambert; Franco Nori

    2008-12-17T23:59:59.000Z

    We consider a nanomechanical resonator coupled to a double quantum dot. We demonstrate how the finite-frequency current noise spectrum through the double quantum dot can be used to distinguish classical and quantum behaviour in the nearby nano-electromechanical resonator. We also show how the full frequency current noise spectrum gives important information on the combined double quantum dot-resonator energy spectrum. Finally, we point out regimes where the quantum state of the resonator becomes squeezed, and also examine the cross-correlated electron-phonon current noise.

  12. Single charge sensing and transport in double quantum dots fabricated from commercially grown Si/SiGe heterostructures

    E-Print Network [OSTI]

    Payette, C; Koppinen, P J; Dovzhenko, Y; Sturm, J C; Petta, J R

    2011-01-01T23:59:59.000Z

    We perform quantum Hall measurements on three types of commercially available modulation doped Si/SiGe heterostructures to determine their suitability for depletion gate defined quantum dot devices. By adjusting the growth parameters, we are able to achieve electron gases with charge densities 1-3 X 10^{11}/cm^2 and mobilities in excess of 100,000 cm^2/Vs. Double quantum dot devices fabricated on these heterostructures show clear evidence of single charge transitions as measured in dc transport and charge sensing and exhibit electron temperatures of 100 mK in the single quantum dot regime.

  13. Single charge sensing and transport in double quantum dots fabricated from commercially grown Si/SiGe heterostructures

    E-Print Network [OSTI]

    C. Payette; K. Wang; P. J. Koppinen; Y. Dovzhenko; J. C. Sturm; J. R. Petta

    2012-03-21T23:59:59.000Z

    We perform quantum Hall measurements on three types of commercially available modulation doped Si/SiGe heterostructures to determine their suitability for depletion gate defined quantum dot devices. By adjusting the growth parameters, we are able to achieve electron gases with charge densities 1-3 X 10^{11}/cm^2 and mobilities in excess of 100,000 cm^2/Vs. Double quantum dot devices fabricated on these heterostructures show clear evidence of single charge transitions as measured in dc transport and charge sensing and exhibit electron temperatures of 100 mK in the single quantum dot regime.

  14. Quasiresonant Excitation of InP/InGaP Quantum Dots Using Second Harmonic Generated in a Photonic Crystal Cavity

    E-Print Network [OSTI]

    Buckley, Sonia; Hatami, Fariba; Vuckovic, Jelena

    2012-01-01T23:59:59.000Z

    Indistinguishable single photons are necessary for quantum information processing applications. Resonant or quasiresonant excitation of single quantum dots provides greater single photon indistinguishability than incoherent pumping, but is also more challenging experimentally. Here, we demonstrate high signal to noise quasiresonant excitation of InP/InGaP quantum dots. The excitation is provided via second harmonic generated from a telecommunications wavelength laser resonant with the fundamental mode of a photonic crystal cavity, fabricated at twice the quantum dot transition wavelength. The second harmonic is generated using the \\chi(2) nonlinearity of the InGaP material matrix.

  15. Quasiresonant Excitation of InP/InGaP Quantum Dots Using Second Harmonic Generated in a Photonic Crystal Cavity

    E-Print Network [OSTI]

    Sonia Buckley; Kelley Rivoire; Fariba Hatami; Jelena Vuckovic

    2012-10-03T23:59:59.000Z

    Indistinguishable single photons are necessary for quantum information processing applications. Resonant or quasiresonant excitation of single quantum dots provides greater single photon indistinguishability than incoherent pumping, but is also more challenging experimentally. Here, we demonstrate high signal to noise quasiresonant excitation of InP/InGaP quantum dots. The excitation is provided via second harmonic generated from a telecommunications wavelength laser resonant with the fundamental mode of a photonic crystal cavity, fabricated at twice the quantum dot transition wavelength. The second harmonic is generated using the \\chi(2) nonlinearity of the InGaP material matrix.

  16. Harry Weerts | Argonne National Laboratory

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

    where he was the spokesman for the Dzero experiment for six years. Weerts has worked in neutrino physics at CERN and hadron collider physics at the Tevatron with the Dzero...

  17. Reflections of Harry J. Longwell

    E-Print Network [OSTI]

    Stephens, Jacqueline

    skills, has remained with me throughout my career. My first mentor at Exxon, then Humble Oil and Refining very similar to that found in the petroleum industry. Consequently, after graduation, I was well technical education and the excellent reputation in the petroleum industry which its graduates have produced

  18. North Carolina Nuclear Profile - Harris

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5 Tables July 1996 Energy Information Administration Office ofthrough 1996)

  19. Arno Harris | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to:Ezfeedflag JumpID-fTriWildcatAntrimArkansas County, Arkansas:ArlingtonArmonk,Iowa:Enhanced

  20. Role of surface states and defects in the ultrafast nonlinear optical properties of CuS quantum dots

    SciTech Connect (OSTI)

    Mary, K. A. Ann; Unnikrishnan, N. V., E-mail: nvu100@yahoo.com [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Philip, Reji [Light and Matter Physics Group, Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India)

    2014-07-01T23:59:59.000Z

    We report facile preparation of water dispersible CuS quantum dots (2–4 nm) and nanoparticles (5–11 nm) through a nontoxic, green, one-pot synthesis method. Optical and microstructural studies indicate the presence of surface states and defects (dislocations, stacking faults, and twins) in the quantum dots. The smaller crystallite size and quantum dot formation have significant effects on the high energy excitonic and low energy plasmonic absorption bands. Effective two-photon absorption coefficients measured using 100 fs laser pulses employing open-aperture Z-scan in the plasmonic region of 800 nm reveal that CuS quantum dots are better ultrafast optical limiters compared to CuS nanoparticles.

  1. Spin and Conductance-Peak-Spacing Distributions in Large Quantum Dots: A Density-Functional Theory Study

    E-Print Network [OSTI]

    Baranger, Harold U.

    of solid-state physics. A semiconductor quantum dot (QD) [1,2]--a nanodevice in which electron motion was regu- lar in shape [24]. Our aim here is to bridge the gap between the two theoretical approaches

  2. High Throughput Synthesis of Uniform Biocompatible Polymer Beads with High Quantum Dot Loading Using Microfluidic Jet-Mode Breakup

    E-Print Network [OSTI]

    Lee, Seung-Kon

    Uniform polymer microbeads with highly loaded quantum dots (QDs) are produced using high-throughput coherent jet breakup of a biocompatible poly(ethylene glycol) diacrylate (PEGDA) prepolymer resin, followed by in-line ...

  3. Nanoscale optical positioning of single quantum dots for bright, pure, and on-demand single-photon emission

    E-Print Network [OSTI]

    Sapienza, Luca; Badolato, Antonio; Srinivasan, Kartik

    2015-01-01T23:59:59.000Z

    Self-assembled, epitaxially-grown InAs/GaAs quantum dots are promising semiconductor quantum emitters that can be integrated on a chip for a variety of photonic quantum information science applications. However, self-assembled growth results in an essentially random in-plane spatial distribution of quantum dots, presenting a challenge in creating devices that exploit the strong interaction of single quantum dots with highly confined optical modes. Here, we present a photoluminescence imaging approach for locating single quantum dots with respect to alignment features with an average (minimum) position uncertainty efficiency (48 % +/- 5 % into a 0.4 numerical aperture lens, close to the theoretically predicted value of 50 %), low multiphoton prob...

  4. Hole Spin Pumping and Re-pumping in a p-type ?-doped InAs Quantum Dot

    E-Print Network [OSTI]

    Konstantinos G. Lagoudakis; Kevin A. Fischer; Tomas Sarmiento; Kai Mueller; Jelena Vu?kovi?

    2014-08-29T23:59:59.000Z

    We have grown high quality p-type {\\delta}-doped InAs quantum dots and have demonstrated coherent spin pumping and repumping of a hole spin in a positively charged quantum dot by means of a single-laser driving scheme under a high magnetic field in the Voigt configuration. Modeling of our system shows excellent qualitative agreement with the experimental findings and further explores the performance of the single-laser scheme for spin pumping and re-pumping.

  5. Chains of quantum dot molecules grown on Si surface pre-patterned by ion-assisted nanoimprint lithography

    SciTech Connect (OSTI)

    Smagina, Zh. V.; Stepina, N. P., E-mail: stepina@isp.nsc.ru; Zinovyev, V. A.; Kuchinskaya, P. A. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Lavrenteva 13, 630090 Novosibirsk (Russian Federation); Novikov, P. L.; Dvurechenskii, A. V. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Lavrenteva 13, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova, 2, 630090 Novosibirsk (Russian Federation)

    2014-10-13T23:59:59.000Z

    An original approach based on the combination of nanoimprint lithography and ion irradiation through mask has been developed for fabrication of large-area periodical pattern on Si(100). Using the selective etching of regions amorphized by ion irradiation ordered structures with grooves and ridges were obtained. The shape and depth of the relief were governed by ion energy and by the number of etching stages as well. Laterally ordered chains of Ge quantum dots were fabricated by molecular beam epitaxy of Ge on the pre-patterned Si substrates. For small amount of Ge deposited chains contain separate quantum dot molecules. The increase of deposition amount leads to overlapping of quantum dot molecules with formation of dense homogeneous chains of quantum dots. It was shown that the residual irradiation-induced bulk defects underneath the grooves suppress nucleation of Ge islands at the bottom of grooves. On pre-patterned substrates with whole defect regions, etched quantum dots grow at the bottom of grooves. The observed location of Ge quantum dots is interpreted in terms of local strain-mediated surface chemical potential which controls the sites of islands nucleation. The local chemical potential is affected by additional strain formed by the residual defects. It was shown by molecular dynamics calculations that these defects form the compressive strain at the bottom of grooves.

  6. Probing the structural dependency of photoinduced properties of colloidal quantum dots using metal-oxide photo-active substrates

    SciTech Connect (OSTI)

    Patty, Kira; Campbell, Quinn; Hamilton, Nathan; West, Robert G. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Sadeghi, Seyed M., E-mail: seyed.sadeghi@uah.edu [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Nano and Micro Device Center, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Mao, Chuanbin [Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2014-09-21T23:59:59.000Z

    We used photoactive substrates consisting of about 1 nm coating of a metal oxide on glass substrates to investigate the impact of the structures of colloidal quantum dots on their photophysical and photochemical properties. We showed during irradiation these substrates can interact uniquely with such quantum dots, inducing distinct forms of photo-induced processes when they have different cores, shells, or ligands. In particular, our results showed that for certain types of core-shell quantum dot structures an ultrathin layer of a metal oxide can reduce suppression of quantum efficiency of the quantum dots happening when they undergo extensive photo-oxidation. This suggests the possibility of shrinking the sizes of quantum dots without significant enhancement of their non-radiative decay rates. We show that such quantum dots are not influenced significantly by Coulomb blockade or photoionization, while those without a shell can undergo a large amount of photo-induced fluorescence enhancement via such blockade when they are in touch with the metal oxide.

  7. Carrier transfer from InAs quantum dots to ErAs metal nanoparticles

    SciTech Connect (OSTI)

    Haughn, C. R.; Chen, E. Y.; Zide, J. M. O.; Doty, M. F., E-mail: doty@udel.edu [Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716 (United States); Steenbergen, E. H.; Bissell, L. J.; Eyink, K. G. [AFRL/RXAN, Wright Patterson AFB, Ohio 45433 (United States)

    2014-09-08T23:59:59.000Z

    Erbium arsenide (ErAs) is a semi-metallic material that self-assembles into nanoparticles when grown in GaAs via molecular beam epitaxy. We use steady-state and time-resolved photoluminescence to examine the mechanism of carrier transfer between indium arsenide (InAs) quantum dots and ErAs nanoparticles in a GaAs host. We probe the electronic structure of the ErAs metal nanoparticles (MNPs) and the optoelectronic properties of the nanocomposite and show that the carrier transfer rates are independent of pump intensity. This result suggests that the ErAs MNPs have a continuous density of states and effectively act as traps. The absence of a temperature dependence tells us that carrier transfer from the InAs quantum dots to ErAs MNPs is not phonon assisted. We show that the measured photoluminescence decay rates are consistent with a carrier tunneling model.

  8. Coherent Optical Spectroscopy of a Single Quantum Dot Via an Off-Resonant Cavity

    E-Print Network [OSTI]

    Arka Majumda; Alexander Papageorge; Erik D. Kim; Michal Bajscy; Hyochul Kim; Pierre Petroff; Jelena Vuckovic

    2011-03-14T23:59:59.000Z

    In recent experiments on coupled quantum dot (QD) optical cavity systems a pronounced interaction between the dot and the cavity has been observed even for detunings of many cavity linewidths. This interaction has been attributed to an incoherent phonon-mediated scattering process and is absent in atomic systems. Here, we demonstrate that despite its incoherent nature, this process preserves the signatures of coherent interaction between a QD and a strong driving laser, which may be observed via the optical emission from the off-resonant cavity. Under bichromatic driving of the QD, the cavity emission exhibits spectral features consistent with optical dressing of the QD transition. In addition to revealing new aspects of the off-resonant QD-cavity interaction, this result provides a new, simpler means of coherently probing QDs than traditional approaches and opens the possibility of employing off-resonant cavities to optically interface QD-nodes in quantum networks.

  9. Enhanced single-photon emission from a quantum dot in a micropost microcavity

    E-Print Network [OSTI]

    Jelena Vuckovic; David Fattal; Charles Santori; Glenn Solomon; Yoshihisa Yamamoto

    2003-07-03T23:59:59.000Z

    We demonstrate a single-photon source based on a quantum dot in a micropost microcavity that exhibits a large Purcell factor together with a small multi-photon probability. For a quantum dot on resonance with the cavity, the spontaneous emission rate is increased by a factor of five, while the probability to emit two or more photons in the same pulse is reduced to 2% compared to a Poisson-distributed source of the same intensity. In addition to the small multi-photon probability, such a strong Purcell effect is important in a single-photon source for improving the photon outcoupling efficiency and the single-photon generation rate, and for bringing the emitted photon pulses closer to the Fourier transform limit.

  10. Reducing charge trapping in PbS colloidal quantum dot solids

    SciTech Connect (OSTI)

    Balazs, D. M.; Nugraha, M. I.; Bisri, S. Z.; Loi, M. A., E-mail: m.a.loi@rug.nl [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747AG (Netherlands); Sytnyk, M.; Heiss, W. [Institute for Semiconductor and Solid State Physics, University of Linz, Altenbergerstr. 69, Linz 4040 (Austria)

    2014-03-17T23:59:59.000Z

    Understanding and improving charge transport in colloidal quantum dot solids is crucial for the development of efficient solar cells based on these materials. In this paper, we report high performance field-effect transistors based on lead-sulfide colloidal quantum dots (PbS CQDs) crosslinked with 3-mercaptopropionic acid (MPA). Electron mobility up to 0.03 cm{sup 2}/Vs and on/off ratio above 10{sup 5} was measured; the later value is the highest in the literature for CQD Field effect transistors with silicon-oxide gating. This was achieved by using high quality material and preventing trap generation during fabrication and measurement. We show that air exposure has a reversible p-type doping effect on the devices, and that intrinsically MPA is an n-type dopant for PbS CQDs.

  11. All-electrical single-electron shuttle in a silicon quantum dot

    E-Print Network [OSTI]

    Chan, K W; Kemppinen, A; Lai, N S; Tan, K Y; Lim, W H; Dzurak, A S

    2011-01-01T23:59:59.000Z

    We report on single-electron shuttling experiments with a silicon metal-oxide-semiconductor quantum dot at 300 mK. Our system consists of an accumulated electron layer at the Si/SiO2 interface below an aluminum top gate with two additional barrier gates used to deplete the electron gas locally and to define a quantum dot. Directional single-electron shuttling from the source and to the drain lead is achieved by applying a dc source-drain bias while driving the barrier gates with an ac voltage of frequency fp. Current plateaus at integer levels of efp are observed up to fp = 240 MHz operation frequencies. The observed results are explained by a sequential tunneling model which suggests that the electron gas may be heated substantially by the ac driving voltage.

  12. Synthesis of Non-blinking Semiconductor Quantum Dots Emitting in the Near-Infrared

    SciTech Connect (OSTI)

    Dennis, Allison M. [Los Alamos National Laboratory; Mangum, Benjamin D. [Los Alamos National Laboratory; Piryatinski, Andrei [Los Alamos National Laboratory; Park, Young-Shin [Los Alamos National Laboratory; Htoon, Han [Los Alamos National Laboratory; Hollingsworth, Jennifer A. [Los Alamos National Laboratory

    2012-06-21T23:59:59.000Z

    Our previous work demonstrates that Quasi-Type II CdSe/CdS core-shell quantum dots with thick shells (3-5 nm) exhibit unique photophysical characteristics, including improved chemical robustness over typical thin-shelled core/shell systems and the elimination of blinking through suppression of nonradiative Auger recombination. Here we describe a new thick-shelled heterostructure, InP/CdS, which exhibits a Type II bandgap alignment producing near-infrared (NIR) emission. Samples with a range of shell thicknesses were synthesized, enabling shell-thickness-dependent study of the absorbance and emission spectra, fluorescence lifetimes, and quantum yields. InP/CdS/ZnS core/shell/shell structures were also synthesized to reduce cadmium exposure for applications in the biological environment. Single particle spectroscopy indicates reduced blinking and improved photostability with increasing shell thickness, resulting in thick-shelled dots that are appropriate for single-particle tracking measurements with NIR emission.

  13. Quantum dot nonlinearity through cavity-enhanced feedback with a charge memory

    E-Print Network [OSTI]

    Morten P. Bakker; Thomas Ruytenberg; Wolfgang Loffler; Ajit V. Barve; Larry Coldren; Martin P. van Exter; Dirk Bouwmeester

    2015-03-27T23:59:59.000Z

    In an oxide apertured quantum dot (QD) micropillar cavity-QED system, we found strong QD hysteresis effects and lineshape modifications even at very low intensities corresponding to less than 0.001 intracavity photons. We attribute this to the excitation of charges by the intracavity field; charges that get trapped at the oxide aperture, where they screen the internal electric field and blueshift the QD transition. This in turn strongly modulates light absorption by cavity QED effects, eventually leading to the observed hysteresis and lineshape modifications. The cavity also enables us to observe the QD dynamics in real time, and all experimental data agrees well with a power-law charging model. This effect can serve as a novel tuning mechanism for quantum dots.

  14. Single photoelectron spin detection and angular momentum transfer in a gate defined quantum dot

    E-Print Network [OSTI]

    Takafumi Fujita; Kazuhiro Morimoto; Haruki Kiyama; Giles Allison; Marcus Larsson; Arne Ludwig; Sascha R. Valentin; Andreas D. Wieck; Akira Oiwa; Seigo Tarucha

    2015-04-14T23:59:59.000Z

    Recent innovations in fabricating nanoscale confined spin systems have enabled investigation of fundamental quantum correlations between single quanta of photons and matter states. Realization of quantum state transfer from photon polarization to electron spin using gate defined quantum dots (QDs) may give evidence of preserved coherence of angular momentum basis states at the photon-spin interface. The interface would enlarge the concept of quantum information technology, in which single photogenerated electron spins are manipulated with the dots, but this remains a serious challenge. Here, we report the detection of single electron spins generated by polarized single photons via a double QD (DQD) to verify the angular momentum transfer from single photons to single electrons. Pauli spin blockade (PSB) is used to project the photoelectron spin state onto the up or down spin state. Our result promises the realization of coherent quantum state transfer and development of hybrid photon and spin quantum technology.

  15. Green's functions technique for calculating the emission spectrum in a quantum dot-cavity system

    E-Print Network [OSTI]

    Edgar A. Gomez; J. D. Hernandez-Rivero; Herbert Vinck-Posada

    2015-02-01T23:59:59.000Z

    We introduce the Green's functions technique as an alternative theory to the quantum regression theorem formalism for calculating the two-time correlation functions in open quantum systems. In particular, we investigate the potential of this theoretical approach by its application to compute the emission spectrum of a dissipative system composed by a single quantum dot inside of a semiconductor cavity. We also describe a simple algorithm based on the Green's functions technique for calculating the emission spectrum of the quantum dot as well as of the cavity which can easily be implemented in any numerical linear algebra package. We find that the Green's functions technique demonstrates a better accuracy and efficiency in the calculation of the emission spectrum and it allows to overcome the inherent theoretical difficulties associated to the direct application of the quantum regression theorem approach.

  16. Phonon-assisted robust and deterministic two-photon biexciton preparation in a quantum dot

    E-Print Network [OSTI]

    S. Bounouar; M. Müller; A. M. Barth; M. Glässl; V. M. Axt; P. Michler

    2014-08-29T23:59:59.000Z

    We investigate both experimentally and theoretically a simple yet more robust and flexible alternative to Rabi oscillation-type biexciton preparation protocols traditionally used for semiconductor quantum dots. The quantum dot is excited by a strong laser pulse positively detuned from the two-photon resonance yielding an on demand initialization of the biexciton state by making use of the phonon-induced thermalization of the photon dressed states. It is shown that for excitation pulses in the picosecond range, a stable and high fidelity of up to $f_{XX}=0.98\\pm 0.01$ is reached. Notably, the generated photons show similar coherence properties as measured in the resonant two-photon scheme. This protocol is a powerful tool for the control of complex solid state systems combining radiative cascades, entanglement and resonant cavity modes.

  17. Height stabilization of GaSb/GaAs quantum dots by Al-rich capping

    SciTech Connect (OSTI)

    Smakman, E. P., E-mail: e.p.smakman@tue.nl; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven (Netherlands); DeJarld, M.; Martin, A. J.; Millunchick, J. [Department of Material Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Luengo-Kovac, M.; Sih, V. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-09-01T23:59:59.000Z

    GaSb quantum dots (QDs) in a GaAs matrix are investigated with cross-sectional scanning tunneling microscopy (X-STM) and photoluminescence (PL). We observe that Al-rich capping materials prevent destabilization of the nanostructures during the capping stage of the molecular beam epitaxy (MBE) growth process and thus preserves the QD height. However, the strain induced by the absence of destabilization causes many structural defects to appear around the preserved QDs. These defects originate from misfit dislocations near the GaSb/GaAs interface and extend into the capping layer as stacking faults. The lack of a red shift in the QD PL suggests that the preserved dots do not contribute to the emission spectra. We suggest that a better control over the emission wavelength and an increase of the PL intensity is attainable by growing smaller QDs with an Al-rich overgrowth.

  18. SiGe/sSi quantum dot electron spin decoherence dependence on $^{73}$Ge

    E-Print Network [OSTI]

    Witzel, Wayne M; Carroll, Malcolm S

    2011-01-01T23:59:59.000Z

    We theoretically study the nuclear spin induced decoherence of a quantum dot in Si that is confined at a SiGe interface. We calculate decoherence time dependence on $^{73}$Ge in the barrier layer to evaluate the importance of Ge as well as Si enrichment for long decoherence times. We use atomistic tight-binding modeling for an accurate account of the electron wavefunction which is particularly important for determining the contact hyperfine interactions with the Ge nuclear spins. We find decoherence times due to Ge spins at natural concentrations to be milliseconds. This suggests SiGe/sSi quantum dot devices employing enriched Si will require enriched Ge as well in order to benefit from long coherence times. We provide a comparison of $T_2$ times for various fractions of nonzero spin isotopes of Si and Ge.

  19. SiGe/Si quantum dot electron spin decoherence dependence on $^{73}$Ge

    E-Print Network [OSTI]

    Wayne M. Witzel; Rajib Rahman; Malcolm S. Carroll

    2012-05-14T23:59:59.000Z

    We theoretically study the nuclear spin induced decoherence of a quantum dot in Si that is confined at a SiGe interface. We calculate decoherence time dependence on $^{73}$Ge in the barrier layer to evaluate the importance of Ge as well as Si enrichment for long decoherence times. We use atomistic tight-binding modeling for an accurate account of the electron wavefunction which is particularly important for determining the contact hyperfine interactions with the Ge nuclear spins. We find decoherence times due to Ge spins at natural concentrations to be milliseconds. This suggests SiGe/Si quantum dot devices employing enriched Si will require enriched Ge as well in order to benefit from long coherence times. We provide a comparison of $T_2$ times for various fractions of nonzero spin isotopes of Si and Ge.

  20. Final LDRD report : infrared detection and power generation using self-assembled quantum dots.

    SciTech Connect (OSTI)

    Cederberg, Jeffrey George; Ellis, Robert; Shaner, Eric Arthur

    2008-02-01T23:59:59.000Z

    Alternative solutions are desired for mid-wavelength and long-wavelength infrared radiation detection and imaging arrays. We have investigated quantum dot infrared photodetectors (QDIPs) as a possible solution for long-wavelength infrared (8 to 12 {mu}m) radiation sensing. This document provides a summary for work done under the LDRD 'Infrared Detection and Power Generation Using Self-Assembled Quantum Dots'. Under this LDRD, we have developed QDIP sensors and made efforts to improve these devices. While the sensors fabricated show good responsivity at 80 K, their detectivity is limited by high noise current. Following efforts concentrated on how to reduce or eliminate this problem, but with no clear path was identified to the desired performance improvements.

  1. Decision making based on optical excitation transfer via near-field interactions between quantum dots

    SciTech Connect (OSTI)

    Naruse, Makoto, E-mail: naruse@nict.go.jp [Photonic Network Research Institute, National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo 184-8795 (Japan); Nomura, Wataru; Ohtsu, Motoichi [Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Aono, Masashi [Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguru-ku, Tokyo 152-8550 (Japan); PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi-shi, Saitama 332-0012 (Japan); Sonnefraud, Yannick; Drezet, Aurélien; Huant, Serge [Université Grenoble Alpes, Inst. NEEL, F-38000 Grenoble (France); CNRS, Inst. NEEL, F-38042 Grenoble (France); Kim, Song-Ju [WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-10-21T23:59:59.000Z

    Optical near-field interactions between nanostructured matters, such as quantum dots, result in unidirectional optical excitation transfer when energy dissipation is induced. This results in versatile spatiotemporal dynamics of the optical excitation, which can be controlled by engineering the dissipation processes and exploited to realize intelligent capabilities such as solution searching and decision making. Here, we experimentally demonstrate the ability to solve a decision making problem on the basis of optical excitation transfer via near-field interactions by using colloidal quantum dots of different sizes, formed on a geometry-controlled substrate. We characterize the energy transfer behavior due to multiple control light patterns and experimentally demonstrate the ability to solve the multi-armed bandit problem. Our work makes a decisive step towards the practical design of nanophotonic systems capable of efficient decision making, one of the most important intellectual attributes of the human brain.

  2. FUNCTIONAL AND MECHANISTIC STUDY OF DOT1L IN MOUSE EMBRYONIC HEMATOPOIESIS

    E-Print Network [OSTI]

    Feng, Yi

    2012-12-31T23:59:59.000Z

    both starved and restimulated MEF ………..………… 51 2.8 Whole-mount immunolabeling for fluorescence …………..……………………... 51 2.9 Analysis of primitive and definitive hematopoiesis by colony forming unit assay ………………………………………………………… 52 2... and KO primitive and definitive erythroid colonies ………….……………………………………………….. 79 Figure 3.8 C-kit/CD41 staining of E10.5 yolk sacs from WT and Dot1L KO embryos ……….……………………………………………………….. 80 Figure 3.9 c-kit+/CD45...

  3. Tuning photoluminescence of reduced graphene oxide quantum dots from blue to purple

    SciTech Connect (OSTI)

    Liu, Fuchi [Physics Department and Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China); College of Physics and Technology, Guangxi Normal University, Guilin 541004 (China); Tang, Tao; Feng, Qian; Li, Ming; Liu, Yuan; Tang, Nujiang, E-mail: tangnujiang@nju.edu.cn; Zhong, Wei; Du, Youwei [Physics Department and Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-04-28T23:59:59.000Z

    Reduced graphene oxide quantum dots (rGOQDs) were synthesized by annealing GOQDs in H{sub 2} atmosphere. The photoluminescence (PL) properties of GOQDs and the rGOQDs samples were investigated. The results showed that compared to GOQDs, a blue to purple tunable PL of rGOQDs can be obtained by regulating the annealing temperature. The increase fraction of the newly formed isolated sp{sup 2} clusters may be responsible for the observed tunable PL.

  4. Probing the ladder of dressed states and nonclassical light generation in quantum dot-cavity QED

    E-Print Network [OSTI]

    Arka Majumdar; Michal Bajcsy; Jelena Vuckovic

    2011-10-21T23:59:59.000Z

    We investigate the photon induced tunneling phenomena in a photonic crystal cavity containing a strongly coupled quantum dot and describe how this tunneling can be used to generate photon states consisting mainly of a particular Fock state. Additionally, we study experimentally the photon-induced tunneling as a function of excitation laser power and frequency and show the signature of second rung of the Jaynes-Cummings Hamiltonian in the observed photon-statistics.

  5. Local droplet etching – Nanoholes, quantum dots, and air-gap heterostructures

    SciTech Connect (OSTI)

    Heyn, Ch.; Sonnenberg, D.; Graf, A.; Kerbst, J.; Stemmann, A.; Hansen, W. [Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany)

    2014-05-15T23:59:59.000Z

    Local droplet etching (LDE) allows the self-organized generation of nanoholes in semiconductor surfaces and is fully compatible with molecular beam epitaxy (MBE). The influence of the process parameters as well as of droplet and substrate materials on the LDE nanohole morphology is discussed. Furthermore, recent applications of LDE, the fabrication of quantum dots by hole filling and the creation of air-gap heterostructures are addressed.

  6. Observations of Rabi oscillations in a non-polar InGaN quantum dot

    SciTech Connect (OSTI)

    Reid, Benjamin P. L., E-mail: benjamin.reid@physics.ox.ac.uk; Chan, Christopher C. S.; Taylor, Robert A. [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Kocher, Claudius [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Konstanz University, Konstanz (Germany); Zhu, Tongtong; Oehler, Fabrice; Emery, Robert; Oliver, Rachel A. [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-06-30T23:59:59.000Z

    Experimental observation of Rabi rotations between an exciton excited state and the crystal ground state in a single non-polar InGaN quantum dot is presented. The exciton excited state energy is determined by photoluminescence excitation spectroscopy using two-photon excitation from a pulsed laser. The population of the exciton excited state is seen to undergo power dependent damped Rabi oscillations.

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

    E-Print Network [OSTI]

    Cao, Guozhong

    .-J. Cheng, Y. Tian, M. S. Liu, J. Zhao, J. A. Bardecker, I. J.-L. Plante, D. S. Ginger, and A. K.-Y. Jen for display backlights," Adv. Mater. (Deerfield Beach Fla.) 22(28), 3076­3080 (2010). 9. Z. Ding, B. M. Quinn quantum dot-organic light-emitting diodes," Appl. Phys. Lett. 98(21), 213102 (2011). 11. K.-Y. Cheng, R

  8. Establishment of correlated states in a quantum dot interacting with an acoustic phonon reservoir

    E-Print Network [OSTI]

    Hui Huang; Gao-xiang Li; Wen-ju Gu; Zbigniew Ficek

    2014-08-20T23:59:59.000Z

    We investigate the effects of a low frequency (acoustic) phonon bath on the dynamics of a quantum dot modelled as a cascade three-level system. We show that the phonon bath appears to the upper transition of the cascade system as a broadband reservoir of inverted rather than conventional harmonic oscillators. The action of the annihilation and creation operators of the inverted oscillator are interchanges relative to those of the usual harmonic oscillator that it serves as a linear amplifier to the system, and thereby gives rise to unusual features in the dynamics of the quantum dot. We find that the phonon bath, although being in a thermal state, affects the quantum dot as a correlated-type reservoir which results in the decay of the system to a correlated two-photon state with the population distribution no longer obeying a Boltzmann distribution. It is particularly interesting that even for a zero temperature phonon reservoir the steady state is a correlated state which under appropriate conditions on the Rabi frequencies and the damping rates can reduce to a strongly correlated pure state. It is shown that the two-photon correlations result in a significant squeezing and strong two-photon correlations in the radiation field emitted by the quantum dot. The presence of the correlations in the system is manifest in the presence of quantum beats in the time evolution of the populations and the radiation intensity. The effect of the ordinary spontaneous emission on the features induced by the phonon bath is also discussed.

  9. Second harmonic generation from direct band gap quantum dots pumped by femtosecond laser pulses

    SciTech Connect (OSTI)

    Liu, Liwei, E-mail: liulw@cust.edu.cn; Wang, Yue; Hu, Siyi; Ren, Yu; Huang, Chen [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022, People's Republic of China and International Joint Research Center for Nanophotonics and Biophotonics, Changchun University of Science and Technology, Changchun, Jilin 130022 (China)

    2014-02-21T23:59:59.000Z

    We report on nonlinear optical experiments performed on Cu{sub 2}S quantum dots (QDs) pumped by femtosecond laser pulses. We conduct a theoretical simulation and experiments to determine their second harmonic generation characteristics. Furthermore, we demonstrate that the QDs have a second harmonic generation conversion efficiency of up to 76%. Our studies suggest that these Cu{sub 2}S QDs can be used for solar cells, bioimaging, biosensing, and electric detection.

  10. Valley splitting in Si quantum dots embedded in SiGe S. Srinivasan,1,2

    E-Print Network [OSTI]

    Rokhinson, Leonid

    Valley splitting in Si quantum dots embedded in SiGe S. Srinivasan,1,2 G. Klimeck,1,2 and L. P subband.4 Recently, calculations predicted that valley splitting in nar- row few nanometers SiGe/Si/SiGe that prediction, which has been explained12 by the disorders of the Si/SiGe interface and in the SiGe buffer

  11. Financial and Technical Resources for Completing Energy Efficiency Projects - The DOT/FTA Perspective

    E-Print Network [OSTI]

    Koski, D.

    2011-01-01T23:59:59.000Z

    ://www.ctod.org/portal/ ? National Transit Institute ? Courses on Land Use/Transportation and Transit Oriented Development ? www.ntionline.com FTA Livability Resource Examples Transportation Planning Capacity Building Program http://planning.dot.gov/ Tools for Regional... Planning for Transit- oriented Development : 1. The Transportation Planning Capacity Building (TPCB) Peer Program is a resource for agencies in need of planning assistance 2. Scenario planning webinars and workshops Additional Resources http://www.sustainablecommunities.gov ...

  12. Photoconductivity of structures based on the SnO{sub 2} porous matrix coupled with core-shell CdSe/CdS quantum dots

    SciTech Connect (OSTI)

    Drozdov, K. A.; Kochnev, V. I.; Dobrovolsky, A. A.; Khokhlov, D. R. [Department of Physics, Moscow State University, 119991 Moscow (Russian Federation)] [Department of Physics, Moscow State University, 119991 Moscow (Russian Federation); Popelo, A. V. [Department of Materials Science, Moscow State University, 119991 Moscow (Russian Federation)] [Department of Materials Science, Moscow State University, 119991 Moscow (Russian Federation); Rumyantseva, M. N.; Gaskov, A. M.; Ryabova, L. I. [Department of Chemistry, Moscow State University, 119991 Moscow (Russian Federation)] [Department of Chemistry, Moscow State University, 119991 Moscow (Russian Federation); Vasiliev, R. B. [Department of Materials Science, Moscow State University, 119991 Moscow (Russian Federation) [Department of Materials Science, Moscow State University, 119991 Moscow (Russian Federation); Department of Chemistry, Moscow State University, 119991 Moscow (Russian Federation)

    2013-09-23T23:59:59.000Z

    Embedding of quantum dots into porous oxide matrixes is a perspective technique for photosensitization of a structure. We show that the sensitization efficiency may be increased by the use of core-shell quantum dots. It is demonstrated that the photoresponse amplitude in a SnO{sub 2} porous matrix with CdSe/CdS quantum dots depends non-monotonously on the number of atomic layers in a shell. The best results are obtained for SnO{sub 2} matrixes coupled with the quantum dots with three atomic layers of a shell. Mechanisms responsible for the structure sensitization are discussed.

  13. Spectral properties of a hybrid-qubit model based on a two-dimensional quantum dot

    E-Print Network [OSTI]

    Alba Y. Ramos; Omar Osenda

    2015-03-27T23:59:59.000Z

    The design and study of hybrid qubits is driven by their ability to get along the best of charge qubits and of spin qubits, {\\em i.e.} the speed of operation of the former and the very slow decoherence rates of the latter ones. There are several proposals to implement hybrid qubits, this works focuses on the spectral properties of an one-electron hybrid qubit. By design, the information would be stored in the electronic spin and the switching between the qubit basis states would be achieved using an external ac electric field. The electron is confined in a two-dimensional quantum dot, whose confining potential is given by a quartic potential, features that are typical of GaAS quantum dots. Besides the confining potential that characterizes the quantum dot there are two static magnetic fields applied to the system, one is a large constant Zeeman field and the other one has a constant gradient. We study the spectral properties of the model Hamiltonian, a Scr\\"odinger-Pauli Hamiltonian with realistic parameters, using the Ritz method. In particular, we look for regions of the parameter space where the lowest eigenenergies and their eigenfunctions allow to define a qubit which is stable under perturbations to the design parameters. We put special attention to the constraints that the design imposes over the magnetic fields, the tuning of the energy gap between the qubit states and the expectation value of the spin operator where the information would be stored.

  14. Heat induced nanoforms of zinc oxide quantum dots and their characterization

    SciTech Connect (OSTI)

    Dey, Anindita [Jadavpur University, Physics Department (India); Basu, Ruma [Jogamaya Devi College, Physics department (India); Das, Sukhen, E-mail: sukhendasju@gmail.com; Nandy, Papiya [Jadavpur University, Physics Department (India)

    2012-02-15T23:59:59.000Z

    In our studies we observed heat induced phase transitions of Zinc oxide quantum dots at 60, 200, 360 and 400 Degree-Sign C, where all the transitions were irreversible except the transition at 60 Degree-Sign C which wasa reversible one. The phase transition at 60 Degree-Sign C indicated a heat induced conformational change which was supported here by studying polarizing micrographs of ZnO quantum dots thin film. The X-ray diffraction studies of the sample fired at different temperatures as indicated by the thermal analysis were performed in order to understand the changes occurred due to transitions. The study also indicated a new and simple approach to develop ZnO nanorods by just thermal decomposition of the ZnO quantum dots firing in furnace at 200 Degree-Sign C with 2h soaking. In order to have a proper insight of the structural changes we performed scanning electron microscopy. Optical characterization was done by UV-Vis and fluorescence spectrophotometer.

  15. Evaluating charge noise acting on semiconductor quantum dots in the circuit quantum electrodynamics architecture

    SciTech Connect (OSTI)

    Basset, J.; Stockklauser, A.; Jarausch, D.-D.; Frey, T.; Reichl, C.; Wegscheider, W.; Wallraff, A.; Ensslin, K.; Ihn, T. [Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich (Switzerland)

    2014-08-11T23:59:59.000Z

    We evaluate the charge noise acting on a GaAs/GaAlAs based semiconductor double quantum dot dipole-coupled to the voltage oscillations of a superconducting transmission line resonator. The in-phase (I) and the quadrature (Q) components of the microwave tone transmitted through the resonator are sensitive to charging events in the surrounding environment of the double dot with an optimum sensitivity of 8.5×10{sup ?5}?e/?(Hz). A low frequency 1/f type noise spectrum combined with a white noise level of 6.6×10{sup ?6} e{sup 2}/Hz above 1?Hz is extracted, consistent with previous results obtained with quantum point contact charge detectors on similar heterostructures. The slope of the 1/f noise allows to extract a lower bound for the double-dot charge qubit dephasing rate which we compare to the one extracted from a Jaynes-Cummings Hamiltonian approach. The two rates are found to be similar emphasizing that charge noise is the main source of dephasing in our system.

  16. Efficient photon extraction from a quantum dot in a broad-band planar cavity antenna

    SciTech Connect (OSTI)

    Ma, Yong, E-mail: y.ma@hw.ac.uk; Kremer, Peter E.; Gerardot, Brian D., E-mail: B.D.Gerardot@hw.ac.uk [Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2014-01-14T23:59:59.000Z

    We analyse the extraction of photons emitted from single InAs quantum dots embedded in planar microcavities. The structures are designed to achieve broad-band operation and high-collection efficiency from a device requiring straightforward fabrication, even with electrical contacts. The designs consist of a quantum dot in a GaAs membrane with asymmetric top and bottom mirrors and a top-side solid immersion lens (SIL). Four separate cases are considered in our design: a GaAs membrane only (case 1), GaAs membrane with a glass SIL on top (case 2), a GaAs membrane with a glass SIL on top and a back mirror consisting of Au (case 3), a GaAs membrane with a glass SIL on top of a distribute Bragg reflector mirror and Au back mirror (case 4). Both finite difference time domain and analytical simulations are used to calculate the electric field, power density, and far-field radiation pattern. For optimized structures (case 4), we obtain significant extraction efficiencies (>50%) with modest Purcell enhancements (?20%) and a large spectral full-width-half-maximum (>100?nm). The high-extraction efficiency, broad-band operation, and facile fabrication make the proposed structures promising for realistic quantum dot devices.

  17. Strain-induced vertical self-organization of semiconductor quantum dots: A computational study

    SciTech Connect (OSTI)

    Shtinkov, N., E-mail: nshtinkov@uottawa.ca [Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa (Ontario) K1N 6N5 (Canada)

    2013-12-28T23:59:59.000Z

    Atomistic strain simulations based on the valence force field method are employed to study the vertical arrangements of semiconductor quantum dot (QD) multilayers. The effects of the QD shape, dimensions, and materials parameters are systematically investigated, varying independently the following parameters: spacer width H, QD lateral spacing D, base b, and height h, slope of the side facets, elastic properties of the dot and the substrate materials, and lattice mismatch between the dot and the substrate. The transition between vertically aligned and anti-aligned structures is found to be determined mainly by the ratios H/D and b/D, as well as by the strain anisotropy of the substrate and to a lesser extent of the QD. The dependence on the QD height h is significant only for steep side facets and large aspect ratios h/b, and the effects of the lattice mismatch strain and the bulk elastic moduli are found to be negligible. The comparison with experimental data shows an excellent agreement with the results from the simulations, demonstrating that the presented analysis results in precise theoretical predictions for the vertical self-organization regime in a wide range of QD materials systems.

  18. Semiconductor quantum dots used in so-called"third-generation"solar cells have the potential to dramatically increase--in some cases even double--the efficiency of converting sunlight

    E-Print Network [OSTI]

    innovati n Semiconductor quantum dots used in so-called"third-generation"solar cells have quantum dots (QDs). These semiconductor nanocrystals typically have diameters from about 2 to 10

  19. Fast and efficient single electron transfer between distant quantum dots S. Hermelin, S. Takada, M. Yamamoto, S. Tarucha, A. D. Wieck et al.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Cooperative Research Project) Quantum Spin Information Project, Atsugi-shi, Kanagawa 243-0198, Japan 5 to manipulate a single electron or its spin quantum coherently.1­5 In addition, double dots--i.e., two dots thanks to surface-acoustic-wave assisted transport. In the context of quantum computing, displaced

  20. Transition to Landau levels in graphene quantum dots F. Libisch, 1, * S. Rotter, 1 J. Gttinger, 2 C. Stampfer, 2,3 and J. Burgdrfer 1

    E-Print Network [OSTI]

    Florian, Libisch

    Transition to Landau levels in graphene quantum dots F. Libisch, 1, * S. Rotter, 1 J. Güttinger, 2 investigate the electronic eigenstates of graphene quantum dots of realistic size #up to 80 nm diameter graphene lattice structure, bulk defects, and localization effects at the edges. Key to the understanding

  1. Transition to Landau levels in graphene quantum dots F. Libisch,1,* S. Rotter,1 J. Gttinger,2 C. Stampfer,2,3 and J. Burgdrfer1

    E-Print Network [OSTI]

    Florian, Libisch

    Transition to Landau levels in graphene quantum dots F. Libisch,1,* S. Rotter,1 J. Güttinger,2 C the electronic eigenstates of graphene quantum dots of realistic size up to 80 nm diameter in the presence-level regime at high fields. Details of this transition sensitively depend on the underlying graphene lattice

  2. Influence of Cationic Precursors on CdS Quantum-Dot-Sensitized Solar Cell Prepared by Successive Ionic Layer Adsorption and

    E-Print Network [OSTI]

    Cao, Guozhong

    as 15% was achieved for perovskite-sensitized solar cells.7 As a derivative of dye-sensitized solarInfluence of Cationic Precursors on CdS Quantum-Dot-Sensitized Solar Cell Prepared by Successive (QDs) onto porous oxide films for quantum-dot-sensitized solar cell (QDSC) applications. In this work

  3. Electrostatically defined quantum dots in a Si/SiGe heterostructure This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    Electrostatically defined quantum dots in a Si/SiGe heterostructure This article has been of Physics Electrostatically defined quantum dots in a Si/SiGe heterostructure A Wild1 , J Sailer1 , J Nützel epitaxially grown Si/SiGe heterostructure. Transport and charge spectroscopy with an additional QD as well

  4. Local optical spectroscopy of self-assembled quantum dots using a near-field optical fiber probe to induce a localized strain field

    E-Print Network [OSTI]

    . The dot density is 2 1010 cm 2 , the average lateral dot size is 18 nm, and the sample has a peak emission limit to the stresses: 1 the finite compressive strength of glass and 2 buckling of the tip for the buckling of a beam holds that the maximum axial force before any possibility of buckling is given by Fmax

  5. Fluorescence relaxation dynamics of CdSe and CdSe/CdS core/shell quantum dots

    SciTech Connect (OSTI)

    Kaur, Gurvir; Kaur, Harmandeep [Centre of Advanced Study in Physics, Department of Physics, Panjab University, Chandigarh-160014 (India); Tripathi, S. K., E-mail: surya@pu.ac.in [Centre of Advanced Study in Physics, Panjab University, Chandigarh- 160014 (India)

    2014-04-24T23:59:59.000Z

    Time-resolved fluorescence spectra for colloidal CdSe and CdSe/CdS core/shell quantum dots have been investigated to know their electron relaxation dynamics at the maximum steady state fluorescence intensity. CdSe core and CdSe/CdS type I core-shell materials with different shell (CdS) thicknesses have been synthesized using mercaptoacetic acid as a capping agent. Steady state absorption and emission studies confirmed successful synthesis of CdSe and CdSe/CdS core-shell quantum dots. The fluorescence shows a tri-exponential decay with lifetimes 57.39, 7.82 and 0.96 ns for CdSe quantum dots. The lifetime of each recombination decreased with growth of CdS shell over the CdSe core, with maximum contribution to fluorescence by the fastest transition.

  6. An electrically driven quantum dot-in-nanowire visible single photon source operating up to 150 K

    SciTech Connect (OSTI)

    Deshpande, Saniya; Bhattacharya, Pallab [Center for Photonics and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)] [Center for Photonics and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

    2013-12-09T23:59:59.000Z

    We demonstrate electrically pumped single photon emission up to 150 K from a single InGaN quantum dot embedded in a GaN nanowire junction diode. The InGaN dot-in-nanowire p-n junctions were grown on silicon by molecular beam epitaxy. The exciton electroluminescence from individual dot-in-nanowires is in the green spectral range (? ? 520 nm) and is detectable up to 150 K. Second order autocorrelation measurements performed at the exciton energy at an ambient temperature of 125 K show a background corrected g{sup (2)}(0) equal to 0.35, indicating dominant single photon emission. The steady state nanowire temperature under these conditions is estimated to be 150 K due to Joule heating induced by the large nanowire series resistance. Time resolved photoluminescence measurements yield an exciton radiative lifetime of 1.1 ns.

  7. Highly uniform, multi-stacked InGaAs/GaAs quantum dots embedded in a GaAs nanowire

    SciTech Connect (OSTI)

    Tatebayashi, J., E-mail: tatebaya@iis.u-tokyo.ac.jp; Ota, Y. [NanoQUINE, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Ishida, S.; Nishioka, M.; Iwamoto, S.; Arakawa, Y. [NanoQUINE, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2014-09-08T23:59:59.000Z

    We demonstrate a highly uniform, dense stack of In{sub 0.22}Ga{sub 0.78}As/GaAs quantum dot (QD) structures in a single GaAs nanowire (NW). The size (and hence emission energy) of individual QD is tuned by careful control of the growth conditions based on a diffusion model of morphological evolution of NWs and optical characterization. By carefully tailoring the emission energies of individual QD, dot-to-dot inhomogeneous broadening of QD stacks in a single NW can be as narrow as 9.3?meV. This method provides huge advantages over traditional QD stack using a strain-induced Stranski-Krastanow growth scheme. We show that it is possible to fabricate up to 200 uniform QDs in single GaAs NWs using this growth technique without degradation of the photoluminescence intensity.

  8. Solution-processed high-performance colloidal quantum dot tandem photodetectors on flexible substrates

    SciTech Connect (OSTI)

    Jiang, Zhenyu; You, Guanjun; Wang, Li; Liu, Jie; Xu, Jian, E-mail: jianxu@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Hu, Wenjia [China Tianchen Engineering Corporation, Tianjin 300400 (China); Zhang, Yu [State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2014-08-28T23:59:59.000Z

    We report a high-performance colloidal quantum dot (CQD)-based near-infrared tandem photodetector fabricated on flexible substrates via solution-processed method. The tandem photodetector on poly(ethylene terephthalate) substrates exhibited low dark current and high detectivities over ?8.8?×?10{sup 11} Jones at near infrared range at ?0.5?V bias and over ?10{sup 13} Jones near 0 bias. The critical bend radii of ?8?mm and ?3?mm have been demonstrated for tensile and compressive bending, respectively. The performance of photodetectors remains stable under mechanical stress, making PbSe CQD material a promise candidate for flexible infrared sensing applications.

  9. On-chip single photon sources based on quantum dots in photonic crystal structures

    E-Print Network [OSTI]

    Schwagmann, Andre

    2013-02-05T23:59:59.000Z

    of this dissertation have appeared or will appear in form of the following journal articles and contributed talks at international conferences. Articles A. Schwagmann, S. Kalliakos, I. Farrer, J. P. Griffiths, G. A. C. Jones, D. A. Ritchie, and A. J. Shields. “On... -chip single photon emission from an integrated semiconductor quantum dot into a photonic crystal waveguide.” Applied Physics Letters 99, 261108 (2011). A. Schwagmann, S. Kalliakos, D. J. P. Ellis, I. Farrer, J. P. Griffiths, G. A. C. Jones, D. A. Ritchie...

  10. High performance continuous wave 1.3??m quantum dot lasers on silicon

    SciTech Connect (OSTI)

    Liu, Alan Y., E-mail: ayliu01@engineering.ucsb.edu; Norman, Justin [Materials Department, University of California Santa Barbara, California 93106 (United States); Zhang, Chong [Department of Electrical and Computer Engineering, University of California Santa Barbara, California 93106 (United States); Snyder, Andrew; Lubyshev, Dmitri; Fastenau, Joel M.; Liu, Amy W. K. [IQE, Inc., Bethlehem, Pennsylvania 18015 (United States); Gossard, Arthur C.; Bowers, John E. [Materials Department, University of California Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California Santa Barbara, California 93106 (United States)

    2014-01-27T23:59:59.000Z

    We demonstrate record performance 1.3??m InAs quantum dot lasers grown on silicon by molecular beam epitaxy. Ridge waveguide lasers fabricated from the as-grown material achieve room temperature continuous wave thresholds as low as 16?mA, output powers exceeding 176 mW, and lasing up to 119?°C. P-modulation doping of the active region improves T{sub 0} to the range of 100–200?K while maintaining low thresholds and high output powers. Device yield is presented showing repeatable performance across different dies and wafers.

  11. An intentionally positioned (In,Ga)As quantum dot in a micron sized light emitting diode

    SciTech Connect (OSTI)

    Mehta, M.; Michaelis de Vasconcellos, S.; Zrenner, A.; Meier, C. [Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), University of Paderborn, Warburger Street 100, 33098 Paderborn (Germany); Reuter, D.; Wieck, A. D. [Applied Solid State Physics, Ruhr-University of Bochum, Universitaetsstr. 150, 44780 Bochum (Germany)

    2010-10-04T23:59:59.000Z

    We have integrated individual (In,Ga)As quantum dots (QDs) using site-controlled molecular beam epitaxial growth into the intrinsic region of a p-i-n junction diode. This is achieved using an in situ combination of focused ion beam prepatterning, annealing, and overgrowth, resulting in arrays of individually electrically addressable (In,Ga)As QDs with full control on the lateral position. Using microelectroluminescence spectroscopy we demonstrate that these QDs have the same optical quality as optically pumped Stranski-Krastanov QDs with random nucleation located in proximity to a doped interface. The results suggest that this technique is scalable and highly interesting for different applications in quantum devices.

  12. Nonlinear Temporal Dynamics of Strongly Coupled Quantum Dot-Cavity System

    E-Print Network [OSTI]

    Arka Majumdar; Dirk Englund; Michal Bajcsy; Jelena Vuckovic

    2011-10-20T23:59:59.000Z

    We theoretically analyze and simulate the temporal dynamics of strongly coupled quantum dot-cavity system driven by a resonant laser pulse. We observe the signature of Rabi oscillation in the time resolved response of the system (i.e., in the numerically calculated cavity output), derive simplified linear and non-linear semi-classical models that approximate well the system's behavior in the limits of high and low power drive pulse, and describe the role of quantum coherence in the exact dynamics of the system. Finally, we also present experimental data showing the signature of the Rabi oscillation in time domain.

  13. SiGe quantum dots for fast hole spin Rabi oscillations

    SciTech Connect (OSTI)

    Ares, N.; Prager, A.; De Franceschi, S. [SPSMS/LaTEQS, CEA-INAC/UJF-Grenoble 1, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France)] [SPSMS/LaTEQS, CEA-INAC/UJF-Grenoble 1, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Katsaros, G. [SPSMS/LaTEQS, CEA-INAC/UJF-Grenoble 1, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France) [SPSMS/LaTEQS, CEA-INAC/UJF-Grenoble 1, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Johannes Kepler University, Institute of Semiconductor and Solid State Physics, Altenbergerstr. 69, 4040 Linz (Austria); Golovach, V. N. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany) [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU) and Donostia International Physics Center DIPC, E-20018 San Sebastián (Spain); IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao (Spain); Zhang, J. J. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)] [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Glazman, L. I. [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States)] [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Schmidt, O. G. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany) [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Center for Advancing Electronics Dresden, TU Dresden (Germany)

    2013-12-23T23:59:59.000Z

    We report on hole g-factor measurements in three terminal SiGe self-assembled quantum dot devices with a top gate electrode positioned very close to the nanostructure. Measurements of both the perpendicular as well as the parallel g-factor reveal significant changes for a small modulation of the top gate voltage. From the observed modulations, we estimate that, for realistic experimental conditions, hole spins can be electrically manipulated with Rabi frequencies in the order of 100?MHz. This work emphasises the potential of hole-based nano-devices for efficient spin manipulation by means of the g-tensor modulation technique.

  14. Strain-induced self-assembly of Ge nanodashes, nanodumbbells, and dot chains on Si(001)

    SciTech Connect (OSTI)

    Zhang, J. J. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany) [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany); Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Schmidt, O. G. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany) [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany); Center for Advancing Electronics Dresden, TU Dresden (Germany)

    2013-09-30T23:59:59.000Z

    We investigate the growth of self-assembled Ge nanostructures on top of embedded Ge nanowires on Si(001) substrates. Ge nanostructures, such as nanodashes, nanodumbbells, and dot chains are observed simply by tuning the growth temperature and thickness of the Si spacer between the Ge layers. The self-assembly process is governed by the surface strain fields generated by the embedded Ge nanowires and is well-described by our theoretical calculations. The catalyst-free and horizontal growth of such Ge nanostructures directly on Si(001) is attractive for investigating exotic transport properties through Si/Ge-based quantum devices.

  15. Site control technique for quantum dots using electron beam induced deposition

    SciTech Connect (OSTI)

    Iizuka, Kanji; Jung, JaeHun; Yokota, Hiroshi [Nippon Institute of Technology, 4-1 Gakuendai, Miyashiro, Minami-saitama, Saitama 3458501 (Japan)

    2014-05-15T23:59:59.000Z

    To develop simple and high throughput sit definition technique for quantum dots (QDs), the electron beam induced deposition (EBID) method was used as desorption guide of phosphorus atoms form InP substrate. As the results one or a few indium (In) droplets (DLs) were created in the carbon grid pattern by thermal annealing at a temperature of 450°C for 10 min in the ultra high vacuum condition. The size of In DLs was larger than QDs, but arsenide DLs by molecular beam in growth chamber emitted wavelength of 1.028?m at 50K by photoluminescence measurement.

  16. High excitation power photoluminescence studies of ultra-low density GaAs quantum dots

    SciTech Connect (OSTI)

    Sonnenberg, D.; Graf, A.; Paulava, V.; Heyn, Ch.; Hansen, W. [Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany)

    2013-12-04T23:59:59.000Z

    We fabricate GaAs epitaxial quantum dots (QDs) by filling of self-organized nanoholes in AlGaAs. The QDs are fabricated under optimized process conditions and have ultra-low density in the 10{sup 6} cm{sup ?2} regime. At low excitation power the optical emission of single QDs exhibit sharp excitonic lines, which are attributed to the recombination of excitonic and biexcitonic states. High excitation power measurements reveal surprisingly broad emission lines from at least six QD shell states.

  17. Slow-light propagation using mode locking of spin precession in quantum dots

    SciTech Connect (OSTI)

    Shabaev, A. [George Mason University, Fairfax Virginia 22030 (United States); Dutton, Z. [Raytheon BBN Technologies, 10 Moulton Street, Cambridge, Massachusetts 02138 (United States); Naval Research Laboratory, Washington, D.C. 20375 (United States); Kennedy, T. A.; Efros, Al. L. [Naval Research Laboratory, Washington, D.C. 20375 (United States)

    2010-11-15T23:59:59.000Z

    We propose using mode locking to enable coherent nonlinear optical effects in inhomogenously broadened spin ensembles. We carry out detailed calculations for quantum dot systems in which increased spin coherence via mode locking has been recently observed [A. Greilich et al., Science 313, 341 (2006); 317, 1896 (2007)]. We show how, in the presence of spin locking, a strong pulse-matching effect occurs, providing a powerful tool for high-bandwidth linear optical processing. We then go on to study 'slow light' in this system and show that high-bandwidth pulses can be controllably delayed by a time comparable to the pulse width.

  18. Semiconductor quantum dots enhanced graphene/CdTe heterostructure solar cells by photo-induced doping

    E-Print Network [OSTI]

    Li, Xiaoqiang; Wang, Peng; Xu, Zhijuan; Zhong, Huikai; Wu, Zhiqian; Lin, Shisheng

    2015-01-01T23:59:59.000Z

    Photo-induced doping is employed into graphene based solar cell through designing of a novel type of solar cell based on graphene/CdTe Schottky heterostructure. By coating a layer of ultrathin CdSe quantum dots onto graphene/CdTe heterostructure, the performance of the graphene/CdTe solar cell is improved by about 50%. Photo-induced doping is mainly accounted for this enhancement, as evidenced by resistance, photoluminescence and quantum efficiency measurements. This work demonstrates a general and feasible way of designing novel type of solar cells based on two dimensional materials/semiconductor heterostructures.

  19. Spectral dependence of the linewidth enhancement factor in quantum dot lasers

    SciTech Connect (OSTI)

    Zubov, F. I., E-mail: fedyazu@mail.ru [Russian Academy of Sciences, St. Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation); Shernyakov, Yu. M.; Maximov, M. V. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Zhukov, A. E. [Russian Academy of Sciences, St. Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation); Livshits, D. A. [Innolume GmbH (Germany); Payusov, A. S.; Nadtochiy, A. M. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Savelyev, A. V.; Kryzhanovskaya, N. V. [Russian Academy of Sciences, St. Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation); Gordeev, N. Yu. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-12-15T23:59:59.000Z

    The spectral analysis of amplified spontaneous emission is used to determine the linewidth enhancement factor (?-factor) in lasers based on InAs/InGaAs quantum dots (QDs) in a wide spectral range near the ground-state optical transition energy. The effect of the pump current and number of QDs on the spectral dependences of the ?-factor is examined. The temperature dependence of the spectra of the ?-factor is experimentally determined for the first time for lasers with InAs/InGaAs QDs. An explanation is suggested for the observed anomalous decrease in the ?-factor with increasing temperature.

  20. Maximal tripartite entanglement between singlet-triplet qubits in quantum dots

    E-Print Network [OSTI]

    Tuukka Hiltunen; Ari Harju

    2013-10-24T23:59:59.000Z

    Singlet-triplet states in double quantum dots are promising realizations of qubits, and capacitive coupling can be used to create entanglement between these qubits. We propose an entangling three-qubit gate of singlet-triplet qubits in a triangular setup. Our simulations using a realistic microscopic model show that a maximally entangled Greenberger-Horne-Zeilinger state can be generated as the qubits are evolved under exchange. Furthermore, our analysis for the gate operation can be used to extract the actual experimental pulse sequence needed to realize this.

  1. Analysis of InAs/GaAs quantum dot solar cells using Suns-Voc measurements

    E-Print Network [OSTI]

    Beattie, N. S.; Zoppi, G.; See, P.; Farrer, I.; Duchamp, M.; Morrison, D. J.; Miles, R. W.; Ritchie, D. A.

    2014-08-06T23:59:59.000Z

    . Appl. Phys. 32 (1961) 510. [10] G. Wei, K. Shiu, N.C. Giebink, S.R. Forrest, Thermodynamic limits of quantum photovoltaic cell efficiency, Appl. Phys. Lett. 91 (2007) 223507. [11] A. Martí, A. Luque, Comment on Thermodynamics limits of quantum photo... /GaAs quantum dot solar cells and the influence on the open circuit voltage, Appl. Phys. Lett. 97 (2010) 123505. [26] A. Martí, A. Luque, Next Generation Photovoltaics: High Efficiency Through Full Spectrum Utilization, IOP Publishing, Bristol, UK, 2004. [27] H...

  2. Nonlocal biphoton generation in Werner state from a single semiconductor quantum dot

    E-Print Network [OSTI]

    H. Kumano; H. Nakajima; T. Kuroda; T. Mano; K. Sakoda; I. Suemune

    2014-08-01T23:59:59.000Z

    We demonstrate Werner-like polarization-entangled state generation disapproving local hidden variable theory from a single semiconductor quantum dot. By exploiting tomographic analysis with temporal gating, we find biphoton states are mapped on the Werner state, which is crucial for quantum information applications due to its versatile ramifications such as usefulness to teleportation. Observed time evolution of the biphoton state brings us systematic understanding on a relationship between tomographically reconstructed biphoton state and a set of parameters characterizing exciton state including fine-structure splitting and cross-dephasing time.

  3. Shaping the composition profiles in heteroepitaxial quantum dots: Interplay of thermodynamic and kinetic effects

    SciTech Connect (OSTI)

    Georgiou, C. [Research Unit for Nanostructured Materials Systems, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus); Leontiou, T. [Research Unit for Nanostructured Materials Systems, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus); General Department, Frederich University, 1036 Nicosia (Cyprus); Kelires, P. C., E-mail: pantelis.kelires@cut.ac.cy [Research Unit for Nanostructured Materials Systems, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus); Department of Mechanical and Materials Science Engineering, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol (Cyprus)

    2014-07-15T23:59:59.000Z

    Atomistic Monte Carlo simulations, coupling thermodynamic and kinetic effects, resolve a longstanding controversy regarding the origin of composition profiles in heteroepitaxial SiGe quantum dots. It is shown that profiles with cores rich in the unstrained (Si) component derive from near-equilibrium processes and intraisland diffusion. Profiles with cores rich in the strained (Ge) component are of nonequilibrium nature, i.e., they are strain driven but kinetically limited. They are shaped by the distribution of kinetic barriers of atomic diffusion in the islands. The diffusion pathways are clearly revealed for the first time. Geometrical kinetics play a minor role.

  4. Fabrication and characterization of p-channel Si double quantum dots

    SciTech Connect (OSTI)

    Yamada, Ko; Kambara, Tomohiro; Oda, Shunri [Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Kodera, Tetsuo, E-mail: kodera.t.ac@m.titech.ac.jp [Department of Physical Electronics, Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan)

    2014-09-15T23:59:59.000Z

    Lithographically defined p-channel Si single hole transistors (SHTs) and double quantum dot (DQD) devices are fabricated and characterized. Coulomb oscillations are clearly evident at a temperature of 4.2?K. The charging energy and the diameter of the SHT are estimated from the Coulomb diamonds. Honeycomb-like charge stability diagrams are observed from measurements of the DQD devices. Single hole transitions through the DQD are detected using an integrated SHT as a charge sensor, and a few-hole regime of the DQD is observed.

  5. Secondary treatment of films of colloidal quantum dots for optoelectronics and devices produced thereby

    DOE Patents [OSTI]

    Semonin, Octavi Escala; Luther, Joseph M; Beard, Matthew C; Chen, Hsiang-Yu

    2014-04-01T23:59:59.000Z

    A method of forming an optoelectronic device. The method includes providing a deposition surface and contacting the deposition surface with a ligand exchange chemical and contacting the deposition surface with a quantum dot (QD) colloid. This initial process is repeated over one or more cycles to form an initial QD film on the deposition surface. The method further includes subsequently contacting the QD film with a secondary treatment chemical and optionally contacting the surface with additional QDs to form an enhanced QD layer exhibiting multiple exciton generation (MEG) upon absorption of high energy photons by the QD active layer. Devices having an enhanced QD active layer as described above are also disclosed.

  6. Statistical distributions of level widths and conductance peaks in irregularly shaped quantum dots

    SciTech Connect (OSTI)

    Alhassid, Y.; Lewenkopf, C.H. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520 (United States)] [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520 (United States); [Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States)

    1995-11-20T23:59:59.000Z

    Analytical expressions for width and conductance peak distributions for quantum dots with multichannel leads in the Coulomb blockade regime are presented for both limits of conserved and broken time-reversal symmetry. The results are valid for any number of nonequivalent and correlated channels, and the distributions are expressed in terms of the channel correlation matrix {ital M} in each lead. The matrix {ital M} is also given in closed form. A chaotic billiard is used as a model to test numerically the theoretical predictions. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

  7. Mid infrared optical properties of Ge/Si quantum dots with different doping level

    SciTech Connect (OSTI)

    Sofronov, A. N.; Firsov, D. A.; Vorobjev, L. E.; Shalygin, V. A.; Panevin, V. Yu.; Vinnichenko, M. Ya. [St. Petersburg State Polytechnic University, Polytechnicheskaya str. 29, St. Petersburg (Russian Federation); Tonkikh, A. A. [Max Planck Institute of Microstructure Physics, Weinberg 2 D-06120, Halle (Saale) (Germany); Danilov, S. N. [University of Regensburg, Regensburg (Germany)

    2013-12-04T23:59:59.000Z

    Optical characterization of the Ge/Si quantum dots using equilibrium and photo-induced absorption spectroscopy in the mid-infrared spectral range was performed in this work. Equilibrium absorption spectra were measured in structures with various doping levels for different light polarizations. Photo-induced absorption spectra measured in undoped structure under interband optical excitation of non-equilibrium charge carriers demonstrate the same features as doped sample in equilibrium conditions. Hole energy spectrum was determined from the analysis of experimental data.

  8. TxDOT - Right of Way Forms webpage | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro IndustriesTown of Ladoga, IndianaTurtle Airships Jump to:TwiggsJemezwells. (SINDA-3GTxDOT

  9. Quantum Dot Tracers for Use in Engineered Geothermal | Department of Energy

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn'tOrigin of ContaminationHubs+18, 2012 Qualified Energy ConservationDepartmentQuantum Dot Tracers

  10. Liquid-phase plasma synthesis of silicon quantum dots embedded in carbon matrix for lithium battery anodes

    SciTech Connect (OSTI)

    Wei, Ying [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); College of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121000 (China); Yu, Hang; Li, Haitao; Ming, Hai; Pan, Keming; Huang, Hui [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China)

    2013-10-15T23:59:59.000Z

    Graphical abstract: - Highlights: • Silicon quantum dots embedded in carbon matrix (SiQDs/C) were fabricated. • SiQDs/C exhibits excellent battery performance as anode materials with high specific capacity. • The good performance was attributed to the marriage of small sized SiQDs and carbon. - Abstract: Silicon quantum dots embedded in carbon matrix (SiQDs/C) nanocomposites were prepared by a novel liquid-phase plasma assisted synthetic process. The SiQDs/C nanocomposites were demonstrated to show high specific capacity, good cycling life and high coulmbic efficiency as anode materials for lithium-ion battery.

  11. Room temperature infrared photoresponse of self assembled Ge/Si (001) quantum dots grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Singha, R. K.; Manna, S.; Das, S.; Dhar, A.; Ray, S. K. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2010-06-07T23:59:59.000Z

    We report on the observation of intraband near infrared (approx3.1 mum) and mid infrared (approx6.2 mum) photocurrent response at room temperature using Ge/Si self-assembled quantum dots grown by molecular beam epitaxy. Due to the bimodal size distribution and SiGe intermixing, distinguishable photoluminescence transitions are observed at 10 K, below and above the optical band gap of bulk Ge. The observed redshift in photocurrent with increasing temperature has been explained by the excitonic electric field originated due to infrared excitation at low temperatures. A good correlation between the spectral photocurrent response and photoluminescence of the quantum dots has been established.

  12. Theoretical simulation of carrier capture and relaxation rates in quantum-dot semiconductor optical amplifiers

    SciTech Connect (OSTI)

    Wu, Yunhu [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); Department of Physics, Kashi Normal College, Kashi 844006 (China); Zhang, Guoping, E-mail: gpzhang@phy.ccnu.edu.cn [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); Guo, Ling; Qi, Guoqun [Department of Physics, Kashi Normal College, Kashi 844006 (China); Li, Xiaoming [Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-06-14T23:59:59.000Z

    Based on Auger scattering mechanism, carrier-carrier scattering dynamics between the two-dimensional carrier reservoir (also called wetting layer, i.e., WL) and the confined quantum dot ground and first excited state in quantum-dot semiconductor optical amplifiers (QD-SOAs) are investigated theoretically in this paper. The scattering rates for independent electron and hole densities are calculated. The results show an ultra-fast carrier capture (relaxation) rate up to 1 ps{sup ?1}, and there is a complex dependence of the Coulomb scattering rates on the WL electron and hole densities. In addition, due to the different effective mass and the level distribution, the scattering rates for electron and hole are very different. Finally, in order to provide a direction to control (increase or decrease) the input current in realistic QD-SOA systems, a simple method is proposed to determine the trends of the carrier recovery rates with the WL carrier densities in the vicinity of the steady-state.

  13. Quantum-dot all-optical logic in a structured vacuum

    SciTech Connect (OSTI)

    Ma Xun; John, Sajeev [Department of Physics, University of Toronto, Toronto, M5S 1A7 (Canada)

    2011-07-15T23:59:59.000Z

    We demonstrate multiwavelength channel optical logic operations on the Bloch vector of a quantum two-level system in the structured electromagnetic vacuum of a bimodal photonic crystal waveguide. This arises through a bichromatic strong-coupling effect that enables unprecedented control over single quantum-dot (QD) excitation through two beams of ultrashort femtojoule pulses. The second driving pulse (signal) with slightly different frequency and weaker strength than the first (holding) pulse leads to controllable strong modulation of the QD Bloch vector evolution path. This occurs through resonant coupling of the signal pulse with the Mollow sideband transitions created by the holding pulse. The movement of the Mollow sidebands during the passage of the holding pulse leads to an effective chirping in transition frequency seen by the signal. Bloch vector dynamics in the rotating frame of the signal pulse and within the dressed-state basis created by the holding pulse reveals that this chirped coupling between the signal pulse and the Mollow sidebands leads to either augmentation or negation of the final quantum-dot population (after pulse passage) compared to the outcome of the holding pulse alone and depending on the relative frequencies of the pulses. By making use of this extra degree of freedom for ultrafast control of QD excitations, applications in ultrafast all-optical logic and, or, and not gates are proposed in the presence of significant (0.1) THz nonradiative dephasing and (about 1%) inhomogeneous broadening.

  14. Revolutionary Method for Increasing the Efficiency of White Light Quantum Dot LEDs

    SciTech Connect (OSTI)

    Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

    2011-01-01T23:59:59.000Z

    Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which respec-tively diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal proc-essing (PTP), reduces the number of point defects while main-taining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of the quantum dot nanoparticles. The cur-rent research uses a thermal model to predict annealing tempera-tures during PTP and demonstrates up to a 300% increase in pho-toluminescence for QDs on passive substrates

  15. Effect of Ligands on Characteristics of (CdSe)13 Quantum Dot

    SciTech Connect (OSTI)

    Gao, Yang; Zhou, Bo; Kang, Seung-gu; Xin, Minsi; Yang, Ping; Dai, Xing; Wang, Zhigang; Zhou, Ruhong

    2014-01-01T23:59:59.000Z

    The widespread applications of quantum dots (QDs) have spurred an increasing interest in the study of their coating ligands, which can not only protect the electronic structures of the central QDs, but also control their permeability through biological membranes with both size and shape. In this work, we have used density functional theory (DFT) to investigate the electronic structures of (CdSe)13 passivated by OPMe2(CH2)nMe ligands with different lengths and various numbers of branches (Me=methyl group, n = 0, 1-3). Our results show that the absorption peak in the ultraviolet-visible (UV-vis) spectra displays a clear blue-shift, on the scale of ~100 nm, upon the binding of ligands. Once the total number of ligands bound with (CdSe)13 reached a saturated number (9 or 10), no more blue-shift occurred in the absorption peak in the UV-vis spectra. On the other hand, the aliphatic chain length of ligands has a negligible effect on the optical properties of the QD core. Analyses of the bonding characteristics confirm that optical transitions are dominantly governed by the central QD core rather than the organic passivation. Interestingly, the density of states (DOS) share similar characteristics as vibrational spectra, even though there is no coordination vibration mode between the ligands and the central QD. These findings might provide insights on the material design for the passivation of quantum dots for biomedical applications.

  16. Theory of Linear Optical Absorption in Diamond Shaped Graphene Quantum Dots

    E-Print Network [OSTI]

    Basak, Tista; Shukla, Alok

    2015-01-01T23:59:59.000Z

    In this paper, optical and electronic properties of diamond shaped graphene quantum dots (DQDs) have been studied by employing large-scale electron-correlated calculations. The computations have been performed using the $\\pi$-electron Pariser-Parr-Pople model Hamiltonian, which incorporates long-range Coulomb interactions. The influence of electron-correlation effects on the ground and excited states has been included by means of the configuration-interaction approach, used at various levels. Our calculations have revealed that the absorption spectra are red-shifted with the increasing sizes of quantum dots. It has been observed that the first peak of the linear optical absorption, which represents the optical gap, is not the most intense peak. This result is in excellent agreement with the experimental data, but in stark contrast to the predictions of the tight-binding model, according to which the first peak is the most intense peak, pointing to the importance of electron-correlation effects. Furthermore, a...

  17. TEST & EVALUATION REPORT FOR THE HEDGEHOG-II PACKAGING SYSTEMS DOT-7A TYPE A CONTAINER

    SciTech Connect (OSTI)

    KELLY, D.L.

    2003-12-29T23:59:59.000Z

    This report documents the US. Department of Transportation Specification 7A (DOT-7A) Type A compliance test and evaluation results for the Hedgehog-II packaging systems. The approved Hedgehog-II packaging configurations provide primary and secondary containment. The approved packaging configurations described within this report are designed to ship Type A quantities of radioactive materials, normal form. Contents may be in solid or liquid form. Liquids transported in the approved 1 L glass bottle assembly shall have a specific gravity of less than or equal to 1.6. Liquids transported in all other approved configurations shall have a specific gravity of less than or equal to 2.0. The solid contents, including packaging, are limited in weight to the gross weight of the as-tested liquids and bottles. The approved Hedgehog-II packaging configurations described in this report may be transported by air, and have been evaluated as meeting the applicable International Air Transport Association/International Civil Aviation Organization (IATA/ICAO) Dangerous Goods Regulations in addition to the DOT requirements.

  18. Quantum Dot Light Enhancement Substrate for OLED Solid-State Lighting

    SciTech Connect (OSTI)

    James Perkins; Matthew Stevenson; Gagan Mahan; Seth Coe-Sullivan; Peter Kazlas

    2011-01-21T23:59:59.000Z

    With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitive solution for increasing the light extraction efficiency of OLEDs with efficient and stable color rendering index (CRI) for solid state lighting (SSL). Solution processable quantum dot (QD) films were integrated into OLED ITO-glass substrates to generate tunable white emission from blue emitting OLED) devices as well as outcouple light from the ITO film. This QD light-enhancement substrate (QD-LED) technology demonstrated a 60% increase in OLED forward light out-coupling, a value which increases to 76% when considering total increase in multi-directional light output. The objective for the first year was an 80% increase in light output. This project seeks to develop and demonstrate a cost-competitive solution for realizing increased extraction efficiency organic light emitting devices (OLEDs) with efficient and stable color rendering index (CRI) for SSL. Solution processible quantum dot (QD) films will be utilized to generate tunable white emission from blue emitting phosphorescent OLED (Ph-OLED) devices.

  19. Near-Infrared Localized Surface Plasmon Resonances Arising from Free Carriers in Doped Quantum Dots

    SciTech Connect (OSTI)

    Jain, Prashant K.; Luther, Joey; Ewers, Trevor; Alivisatos, A. Paul

    2010-10-12T23:59:59.000Z

    Quantum confinement of electronic wavefunctions in semiconductor quantum dots (QDs) yields discrete atom-like and tunable electronic levels, thereby allowing the engineering of excitation and emission spectra. Metal nanoparticles, on the other hand, display strong resonant interactions with light from localized surface plasmon resonance (LSPR) oscillations of free carriers, resulting in enhanced and geometrically tunable absorption and scattering resonances. The complementary attributes of these nanostructures lends strong interest toward integration into hybrid nanostructures to explore enhanced properties or the emergence of unique attributes arising from their interaction. However, the physicochemical interface between the two components can be limiting for energy transfer and synergistic coupling within such a hybrid nanostructure. Therefore, it is advantageous to realize both attributes, i.e., LSPRs and quantum confinement within the same nanostructure. Here, we describe well-defined LSPRs arising from p-type carriers in vacancy-doped semiconductor quantum dots. This opens up possibilities for light harvesting, non-linear optics, optical sensing and manipulation of solid-state processes in single nanocrystals.

  20. Engineering the quantum point contact response to single-electron charging in a few-electron quantum-dot circuit

    E-Print Network [OSTI]

    -electron quantum-dot circuit L.-X. Zhang and J. P. Leburtona) Beckman Institute for Advanced Science & Technology Project, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands (Received 3 May =e2 /h (which is halfway between pinch off and the first con- ductance plateau G0=2e2 /h) gives

  1. The dynamics of tunneling into self-assembled InAs dots R. J. Luyken, A. Lorke,a)

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    -defined, nanometer-size quantum dots with sizes in the 10 nm range.1 These systems are of great interest, not only for studying the basic properties of man-made ``artificial atoms,'' but also because of possible device, this degeneracy is lifted by electron­electron interactions, so that groups of charging peaks appear, which

  2. A level set simulation for ordering of quantum dots via cleaved-edge X. B. Niu,1,2

    E-Print Network [OSTI]

    Ratsch, Christian

    applications such as next generation optoelectronic devices.1 For optimal performance of arrays of QDs it is ideal if the size distribution of the dots is rather uniform. Moreover, the exact properties of QDs can energy Etrans is sketched in Fig. 2. Within the method, island boundaries are described by a level set

  3. Modeling Spike Trains from Area This chapter describes the application of a motion energy model to the dynamic dot

    E-Print Network [OSTI]

    Bair, Wyeth

    74 Chapter 6 Modeling Spike Trains from Area MT This chapter describes the application of a motion energy model to the dynamic dot stimulus. We wanted to know whether the precise temporal modulation widely compared to electrophysiological data from both area MT and its V1 inputs (Heeger, 1987; Grzywacz

  4. Green route synthesis of high quality CdSe quantum dots for applications in light emitting devices

    SciTech Connect (OSTI)

    Bera, Susnata, E-mail: susnata.bera@gmail.com [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Singh, Shashi B. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Ray, S.K., E-mail: physkr@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2012-05-15T23:59:59.000Z

    Investigation was made on light emitting diodes fabricated using CdSe quantum dots. CdSe quantum dots were synthesized chemically using olive oil as the capping agent, instead of toxic phosphine. Room temperature photoluminescence investigation showed sharp 1st excitonic emission peak at 568 nm. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting devices were fabricated by solution process. The electroluminescence study showed low turn on voltage ({approx}2.2 V) .The EL peak intensity was found to increase by increasing the operating current. - Graphical abstract: Light emitting diode was fabricated using CdSe quantum dots using olive oil as the capping agent, instead of toxic phosphine. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting device shows strong electroluminescence in the range 630-661 nm. Highlights: Black-Right-Pointing-Pointer CdSe Quantum dots were synthesized using olive oil as the capping agent. Black-Right-Pointing-Pointer Light emitting device was fabricated using CdSe QDs/P3HT polymer heterojunction. Black-Right-Pointing-Pointer The I-V characteristics study showed low turn on voltage at {approx}2.2 V. Black-Right-Pointing-Pointer The EL peak intensity increases with increasing the operating current.

  5. IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 11, NO. 4, JULY 2007 443 Segmentation and Classification of Dot

    E-Print Network [OSTI]

    Lerner, Boaz

    Yeshaya Abstract--Signal segmentation and classification of fluorescence in situ hybridization (FISH classifier (NBC) or a multilayer perceptron is accomplished. When applied to a FISH image database, dot hybridization (FISH), image segmentation, multilayer perceptron (MLP), naive Bayesian classifier (NBC). I

  6. THE JOURNAL OF CHEMICAL PHYSICS 136, 194106 (2012) Trapping photon-dressed Dirac electrons in a quantum dot studied

    E-Print Network [OSTI]

    Mukamel, Shaul

    2012-01-01T23:59:59.000Z

    and bilayer graphene by spatially different potential profiles. Short lived exci- tonic states which are too unique band structure, the charge carriers in graphene are massless Dirac fermions which can cross high to be localized within graphene based quantum dots (QDs). Within a finite spatial region defined by sharp

  7. MODELLING OF THE PERC STRUCTURE WITH STRIPE AND DOT BACK K.R. Catchpole and A.W. Blakers

    E-Print Network [OSTI]

    MODELLING OF THE PERC STRUCTURE WITH STRIPE AND DOT BACK CONTACTS K.R. Catchpole and A.W. Blakers Centre for Sustainable Energy Systems Engineering Department, FEIT, The Australian National University commercial cell designs with only a small increase in process complexity. Optimisation of the PERC structure

  8. Pavement Smoothness for Illinois DOT -Doug Dirks 1. Briefly summarize your current pavement smoothness requirements. See below.

    E-Print Network [OSTI]

    Pavement Smoothness for Illinois DOT - Doug Dirks 1. Briefly summarize your current pavement? N/A Illinois has both standard specifications and a special provision for pavement smoothness-Depth HMA pavements, and PCC Pavements are all included in this special provision. http

  9. Long-time electron spin storage via dynamical suppression of hyperfine-induced decoherence in a quantum dot

    E-Print Network [OSTI]

    by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron and characterized. The impact of system and control nonidealities is also assessed, including the effect.125336 PACS number s : 03.67.Pp, 03.65.Yz, 75.10.Jm, 02.60.Cb I. INTRODUCTION Electron and nuclear spin

  10. The Architecture of Colloidal Quantum Dot Solar Cells: Materials to Illan J. Kramer and Edward H. Sargent*

    E-Print Network [OSTI]

    The Architecture of Colloidal Quantum Dot Solar Cells: Materials to Devices Illan J. Kramer of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada CONTENTS 1. Introduction 863 2. Measuring and Modeling CQD Solar Cells 863 2.1. Solar Cell Characterization Considerations 864 2.2. Drift

  11. Determination of energy scales in few-electron double quantum dots D. Taubert, D. Schuh, W. Wegscheider, and S. Ludwig

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    gate volt- ages to energy differences between the electronic states. The conversion factors devices. We have developed methods to determine the gate voltage to energy conversion accurately in the different regimes of dot-lead tunnel couplings and demonstrate strong variations of the conversion factors

  12. Visualizing and Quantifying Molecular Goodness-of-Fit: Small-probe Contact Dots with Explicit Hydrogen Atoms

    E-Print Network [OSTI]

    Richardson, David

    Visualizing and Quantifying Molecular Goodness-of-Fit: Small-probe Contact Dots with Explicit) for analyzing interaction patterns in the molecules themselves. # 1999 Academic Press Keywords: protein internal, 1711±1733 0022-2836/99/041711±23 $30.00/0 # 1999 Academic Press #12;Introduction Remarkably ordered

  13. Direct observation of superconducting vortex clusters pinned by a periodic array of magnetic dots in ferromagnetic/superconducting hybrid structures

    E-Print Network [OSTI]

    Metlushko, Vitali

    Direct observation of superconducting vortex clusters pinned by a periodic array of magnetic dots in ferromagnetic/superconducting hybrid structures T. Shapoval,1,* V. Metlushko,2 M. Wolf,1 B. Holzapfel,1 V. Neu,1, Illinois 60612, USA Received 13 November 2009; published 11 March 2010 Strong pinning of superconducting

  14. PHYSICAL REVIEW E 85, 031117 (2012) Stochastically driven single-level quantum dot: A nanoscale finite-time thermodynamic

    E-Print Network [OSTI]

    Lindenberg, Katja

    2012-01-01T23:59:59.000Z

    as a nanoscale finite-time thermodynamic machine. The dot is driven by an external stochastic force that switches that extracts heat from the cold reservoir via the work input of the stochastic driving. The efficiency coupling conditions, familiar features are recovered in appropriate limits: Carnot efficiency

  15. Hybrid molecular assemblies composed of hydrogenase enzymes and quantum dots helps to pave the way for the

    E-Print Network [OSTI]

    % wastepaper, including 10% post consumer waste. Lighting Up Enzymes for Solar Hydrogen Production NREL. Scientists at the National Renewable Energy Laboratory (NREL) have combined quan- tum dots, which selectivity and fast turnover of hydrogenase enzymes to achieve light-driven hydrogen (H2) production

  16. Study of the growth mechanisms of GaN/(Al, Ga)N quantum dots: Correlation between structural and optical properties

    SciTech Connect (OSTI)

    Sergent, S. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Universite de Nice Sophia Antipolis, Parc Valrose, F-06102 Nice Cedex 2 (France); Damilano, B.; Huault, T.; Brault, J.; Tottereau, O.; Vennegues, P.; Leroux, M.; Semond, F.; Massies, J. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Korytov, M.

    2011-03-01T23:59:59.000Z

    The ammonia-based molecular beam epitaxy of GaN/(Al, Ga)N quantum dots is investigated using reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy and photoluminescence. The main steps of the formation kinetics are identified and the influence of diffusion and evaporation processes on both the quantum dot and the wetting layer morphology is addressed. The correlation between the optical and structural properties of such structures finally allows for the analysis of matter exchanges between the quantum dots and the wetting layer during capping.

  17. Empowering the Next Generation: Connecting the U.S. and African...

    Broader source: Energy.gov (indexed) [DOE]

    Director Dot Harris meets with Subramania I. Sritharan PhD, P.E., Central State University, and John J. Qu, Ph.D., George Mason University, fellow participants at the May 2014...

  18. The $\\dot{M} - M$ relationship in pre-main sequence stars

    E-Print Network [OSTI]

    C. J. Clarke; J. E. Pringle

    2006-05-15T23:59:59.000Z

    We examine the recent data and analysis of Natta et al. concerning the accretion rate on to young stars as a function of stellar mass, and conclude that the apparently steep dependence of accretion rate on mass is strongly driven by selection/detection thresholds. We argue that a convincing demonstration of a physical relationship between accretion and stellar mass requires further studies which, as is the case for Natta et al., include information on upper limits, and which quantify the possible incompleteness of the sample, at both low and high accretion rates. We point out that the distribution of detections in the ($M, \\dot{M}$)-plane can in principle be used to test conventional accretion disc evolutionary models, and that higher sensitivity observations might be able to test the hypothesis of accelerated disc clearing at late times.

  19. Wavelength-tunable colloidal quantum dot laser on ultra-thin flexible glass

    SciTech Connect (OSTI)

    Foucher, C.; Guilhabert, B.; Laurand, N.; Dawson, M. D. [Institute of Photonics, SUPA, University of Strathclyde, Glasgow (United Kingdom)

    2014-04-07T23:59:59.000Z

    A mechanically flexible and wavelength-tunable laser with an ultra-thin glass membrane as substrate is demonstrated. The optically pumped hybrid device has a distributed feedback cavity that combines a colloidal quantum dot gain film with a grating-patterned polymeric underlayer, all on a 30-?m thick glass sheet. The total thickness of the structure is only 75??m. The hybrid laser has an average threshold fluence of 450?±?80??J/cm{sup 2} (for 5-ns excitation pulses) at an emitting wavelength of 607?nm. Mechanically bending the thin-glass substrate enables continuous tuning of the laser emission wavelength over an 18-nm range, from 600?nm to 618?nm. The correlation between the wavelength tunability and the mechanical properties of the thin laser structure is verified theoretically and experimentally.

  20. Optical and Electrical Measurement of Energy Transfer between Nanocrystalline Quantum Dots and Photosystem I

    SciTech Connect (OSTI)

    Jung, H.; Gulis, G.; Gupta, S.; Redding, K.; Gosztola, D. J.; Wiederrecht, Gary P; Stroscio, M. A.; Dutta, M.

    2010-01-01T23:59:59.000Z

    In the natural photosynthesis process, light harvesting complexes (LHCs) absorb light and pass excitation energy to photosystem I (PSI) and photosystem II (PSII). In this study, we have used nanocrystalline quantum dots (NQDs) as an artificial LHC by integrating them with PSI to extend their spectral range. We have performed photoluminescence (PL) and ultrafast time-resolved absorption measurements to investigate this process. Our PL experiments showed that emission from the NQDs is quenched, and the fluorescence from PSI is enhanced. Transient absorption and bleaching results can be explained by fluorescence resonance energy transfer (FRET) from the NQDs to the PSI. This nonradiative energy transfer occurs in ?6 ps. Current?voltage (I?V) measurements on the composite NQD-PSI samples demonstrate a clear photoresponse.

  1. Ge{sub 1-x}Mn{sub x} heteroepitaxial quantum dots: Growth, morphology, and magnetism

    SciTech Connect (OSTI)

    Kassim, J.; Nolph, C.; Reinke, P.; Floro, J. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Jamet, M. [Institut Nanosciences et Cryogenie/SP2M, CEA-UJF, F-38054 Grenoble (France)

    2013-02-21T23:59:59.000Z

    Heteroepitaxial Ge{sub 1-x}Mn{sub x} quantum dots (QDs) were grown on Si (001) by molecular beam epitaxial co-deposition, with x = 0 to 0.10, in order to explore the interaction between Mn content, surface morphological evolution, and magnetism. Morphological evolution typical of the Ge/Si (001) system was observed, where the effect of Mn on surface morphology is surprisingly minimal at low Mn content, with no obvious surface morphological indicators of second phase formation. As the Mn content increases, secondary phase formation becomes evident, appearing to heterogeneously nucleate on or within Ge QDs. Still higher Mn concentrations lead to extensive second phase formation interspersed with an array of Ge QDs. Although ferromagnetism up to 220 K is observed, likely arising from intermetallic precipitates, there is no clear evidence for room-temperature ferromagnetism associated with a dilute magnetic solution phase.

  2. A scheme comparison of Autler-Townes based slow light in inhomogeneously broadened quantum dot media

    E-Print Network [OSTI]

    Per Lunnemann; Jesper Mørk

    2010-08-23T23:59:59.000Z

    We propose a method to achieve significant optical signal delays exploiting the effect of Autler-Townes splitting in an inhomogeneously broadened quantum dot medium. The absorption and slow-down effects are compared for three schemes i.e. $\\Xi$, V and $\\Lambda$, corresponding to different excitation configurations. Qualitative differences of the V-scheme compared to the $\\Xi$- and $\\Lambda$-scheme are found, which show that features of Autler-Townes splitting are only revealed in the V-scheme. The underlying physical mechanisms causing this discrepancy are analyzed and discussed. Finally we compare field propagation calculations of the schemes showing significantly larger achievable signal delays for the V-scheme despite finite absorption of the coupling field. This opens the possibility for using waveguide structures for both coupling and probe fields, thus significantly increasing the achievable signal delays.

  3. Advanced method for increasing the efficiency of white light quantum dot LEDs

    SciTech Connect (OSTI)

    Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

    2011-01-01T23:59:59.000Z

    Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which, respectively, diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal processing (PTP), reduces the number of point defects while maintaining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of theQD nanoparticles. The current research uses a thermal model to predict annealing temperatures during PTP and demonstrates up to a 300% increase in photoluminescence for QDs on passive substrates.

  4. Controlling the Spontaneous Emission Rate of Single Quantum Dots in a 2D Photonic Crystal

    E-Print Network [OSTI]

    Dirk Englund; David Fattal; Edo Waks; Glenn Solomon; Bingyang Zhang; Toshihiro Nakaoka; Yasuhiko Arakawa; Yoshihisa Yamamoto; Jelena Vuckovic

    2005-04-20T23:59:59.000Z

    We observe large spontaneous emission rate modification of individual InAs Quantum Dots (QDs) in 2D a photonic crystal with a modified, high-Q single defect cavity. Compared to QDs in bulk semiconductor, QDs that are resonant with the cavity show an emission rate increase by up to a factor of 8. In contrast, off-resonant QDs indicate up to five-fold rate quenching as the local density of optical states (LDOS) is diminished in the photonic crystal. In both cases we demonstrate photon antibunching, showing that the structure represents an on-demand single photon source with pulse duration from 210 ps to 8 ns. We explain the suppression of QD emission rate using Finite Difference Time Domain (FDTD) simulations and find good agreement with experiment.

  5. Multiple time scale blinking in InAs quantum dot single-photon sources

    E-Print Network [OSTI]

    Marcelo Davanco; C. Stephen Hellberg; Serkan Ates; Antonio Badolato; Kartik Srinivasan

    2014-04-21T23:59:59.000Z

    We use photon correlation measurements to study blinking in single, epitaxially-grown self-assembled InAs quantum dots situated in circular Bragg grating and microdisk cavities. The normalized second-order correlation function g(2)(\\tau) is studied across eleven orders of magnitude in time, and shows signatures of blinking over timescales ranging from tens of nanoseconds to tens of milliseconds. The g(2)(\\tau) data is fit to a multi-level system rate equation model that includes multiple non-radiating (dark) states, from which radiative quantum yields significantly less than 1 are obtained. This behavior is observed even in situations for which a direct histogramming analysis of the emission time-trace data produces inconclusive results.

  6. Strongly modified four-wave mixing in a coupled semiconductor quantum dot-metal nanoparticle system

    SciTech Connect (OSTI)

    Paspalakis, Emmanuel, E-mail: paspalak@upatras.gr [Materials Science Department, School of Natural Sciences, University of Patras, 265 04 Patras (Greece); Evangelou, Sofia [Materials Science Department, School of Natural Sciences, University of Patras, 265 04 Patras (Greece); Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110 (Greece); Kosionis, Spyridon G.; Terzis, Andreas F. [Department of Physics, School of Natural Sciences, University of Patras, 265 04 Patras (Greece)

    2014-02-28T23:59:59.000Z

    We study the four-wave mixing effect in a coupled semiconductor quantum dot-spherical metal nanoparticle structure. Depending on the values of the pump field intensity and frequency, we find that there is a critical distance that changes the form of the spectrum. Above this distance, the four-wave mixing spectrum shows an ordinary three-peaked form and the effect of controlling its magnitude by changing the interparticle distance can be obtained. Below this critical distance, the four-wave mixing spectrum becomes single-peaked; and as the interparticle distance decreases, the spectrum is strongly suppressed. The behavior of the system is explained using the effective Rabi frequency that creates plasmonic metaresonances in the hybrid structure. In addition, the behavior of the effective Rabi frequency is explained via an analytical solution of the density matrix equations.

  7. Suspending Effect on Low-Frequency Charge Noise in Graphene Quantum Dot

    E-Print Network [OSTI]

    Xiang-Xiang Song; Hai-Ou Li; Jie You; Tian-Yi Han; Gang Cao; Tao Tu; Ming Xiao; Guang-Can Guo; Hong-Wen Jiang; Guo-Ping Guo

    2014-06-16T23:59:59.000Z

    Charge noise is critical in the performance of gate-controlled quantum dots (QDs). Here we show the 1/f noise for a microscopic graphene QD is substantially larger than that for a macroscopic graphene field-effect transistor (FET), increasing linearly with temperature. To understand its origin, we suspended the graphene QD above the substrate. In contrast to large area graphene FETs, we find that a suspended graphene QD has an almost-identical noise level as an unsuspended one. Tracking noise levels around the Coulomb blockade peak as a function of gate voltage yields potential fluctuations of order 1 "{\\mu}eV", almost one order larger than in GaAs/GaAlAs QDs. Edge states rather than substrate-induced disorders, appear to dominate the 1/f noise, thus affecting the coherency of graphene nano-devices.

  8. Light-assisted recharging of graphene quantum dots in fluorographene matrix

    SciTech Connect (OSTI)

    Antonova, I. V. [A.V. Rzhanov Institute of Semiconductor Physics, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Avenue 13, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogov Street 2, Novosibirsk 630090 (Russian Federation); Nebogatikova, N. A.; Prinz, V. Ya. [A.V. Rzhanov Institute of Semiconductor Physics, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Avenue 13, Novosibirsk 630090 (Russian Federation); Popov, V. I.; Smagulova, S. A. [North - East Federal University, Yakutsk (Russian Federation)

    2014-10-07T23:59:59.000Z

    In the present study, the charge transient spectroscopy was used to analyze the transient relaxation of charges in graphene and bilayer-graphene quantum dot (QD) systems formed by chemical functionalization of graphene and few-layer graphene layers. A set of activation energies (one to three different values) for the emission of charges from QDs sized 50 to 70 nm, most likely proceeding via the thermal activation of charge carriers from QD quantum confinement levels, were deduced from measurements performed in the dark. Daylight illumination of samples during measurements was found to result in a strong decrease of the activation energies and in an involvement of an athermal process in the charge relaxation phenomenon. The time of the light-assisted emission of charge carriers from QDs proved to be two to four orders of magnitude shorter than the time of their emission from QDs under no-illumination conditions.

  9. Charge tuning in [111] grown GaAs droplet quantum dots

    SciTech Connect (OSTI)

    Bouet, L.; Vidal, M.; Marie, X.; Amand, T.; Wang, G.; Urbaszek, B. [INSA-CNRS-UPS, LPCNO, Université de Toulouse, 135 Ave. Rangueil, 31077 Toulouse (France); Mano, T.; Ha, N.; Kuroda, T.; Sakoda, K. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Durnev, M. V.; Glazov, M. M.; Ivchenko, E. L. [Ioffe Physical-Technical Institute RAS, 194021 St.-Petersburg (Russian Federation)

    2014-08-25T23:59:59.000Z

    We demonstrate charge tuning in strain free GaAs/AlGaAs quantum dots (QDs) grown by droplet epitaxy on a GaAs(111)A substrate. Application of a bias voltage allows the controlled charging of the QDs from ?3|e| to +2|e|. The resulting changes in QD emission energy and exciton fine-structure are recorded in micro-photoluminescence experiments at T?=?4?K. We uncover the existence of excited valence and conduction states, in addition to the s-shell-like ground state. We record a second series of emission lines about 25?meV above the charged exciton emission coming from excited charged excitons. For these excited interband transitions, a negative diamagnetic shift of large amplitude is uncovered in longitudinal magnetic fields.

  10. Quantum dot Ge/TiO{sub 2} heterojunction photoconductor fabrication and performance

    SciTech Connect (OSTI)

    Church, Carena P.; Carter, Sue A., E-mail: sacarter@ucsc.edu [Department of Physics, University of California Santa Cruz, Santa Cruz, California 95064 (United States); Muthuswamy, Elayaraja; Kauzlarich, Susan M. [Department of Chemistry, University of California Davis, Davis, California 95616 (United States)] [Department of Chemistry, University of California Davis, Davis, California 95616 (United States); Zhai, Guangmei [Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education, Taiyuan University of Science and Technology, Taiyuan, Shanxi 030024 (China)] [Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education, Taiyuan University of Science and Technology, Taiyuan, Shanxi 030024 (China)

    2013-11-25T23:59:59.000Z

    Spun cast TiO{sub 2}-Ge quantum dot (QD) heterojunction type photodetectors have been fabricated and characterized, with interest paid to photocurrent enhancements related to device design. Performance as a function of absorber layer thickness, QD size, and back contact is investigated. We have achieved ultra-thin (?200?nm) devices with photocurrents at 0.5?V of 10{sup ?4} A cm{sup ?2} while the thickest devices have photocurrents at 0.5?V of 10{sup ?2} A cm{sup ?2} with on-off ratios >100, which represents 5 orders of magnitude increase in photocurrents over previously fabricated Ge QD devices. At 0.5?V bias, the currents in our devices are competitive with thin-film Ge photovoltaics.

  11. Morphological evolution of seeded self-limiting quantum dots on patterned substrates

    SciTech Connect (OSTI)

    Dimastrodonato, Valeria; Pelucchi, Emanuele [Tyndall National Institute, University College Cork, Dyke Parade, Cork (Ireland); Vvedensky, Dimitri D. [The Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom)

    2013-12-04T23:59:59.000Z

    We present experimental data and a comprehensive theoretical model for the self-limiting growth during metalorganic vaporphase epitaxy of Al{sub x}Ga{sub 1?x}As within tetrahedral recesses etched in GaAs(111)B substrates. A self-limiting profile develops during growth, accompanied by Ga segregation, and leads to the formation of quantum dots and vertical quantum wires along the base and central axis of the recesses, respectively. A theoretical model based on reaction-diffusion equations for the precursor kinetics, adatom diffusion and incorporation, on each crystallographic facet composing the template, is formulated: our theory explains, and reproduces with good agreement, all the experimental trends of the self-limiting profile and alloy segregation dependence on material composition and growth temperature. These results represent a promising route toward a reproducible on-demand design of seeded lowdimensional nanostructures grown on any patterned surface.

  12. Small quantum dots of diluted magnetic III-V semiconductor compound

    E-Print Network [OSTI]

    Pozhar, Liudmila A

    2012-01-01T23:59:59.000Z

    In this chapter quantum many body theoretical methods have been used to study properties of GaAs - and InAs - based, small semiconductor compound quantum dots (QDs) containing manganese or vanadium atoms. Interest to such systems has grown since experimental synthesis of nanoscale magnetic semiconductors, that is, nanoscale semiconductor compounds with enhanced magnetic properties. This enhancement is achieved by several methods, and in particular by doping common semiconductor compounds with some atoms, such as Mn or V. Experimental studies indicate that the electron spin density in the case of thin nanoscale magnetic semiconductor films and QDs may be delocalized. As described in this chapter, quantum many body theory-based, computational synthesis (i.e., virtual synthesis) of tetrahedral symmetry GaAs and InAs small pyramidal QDs doped with sabstitutional Mn or V atoms proves that such QDs are small magnetic molecules that indeed, possess delocalized and polarized electron spin density. Such delocalization...

  13. Decoherence and Quantum Interference assisted electron trapping in a quantum dot

    E-Print Network [OSTI]

    Ahmed El Halawany; Michael N. Leuenberger

    2013-08-08T23:59:59.000Z

    We present a theoretical model for the dynamics of an electron that gets trapped by means of decoherence and quantum interference in the central quantum dot (QD) of a semiconductor nanoring (NR) made of five QDs, between 100 K and 300 K. The electron's dynamics is described by a master equation with a Hamiltonian based on the tight-binding model, taking into account electron-LO phonon interaction (ELOPI). Based on this configuration, the probability to trap an electron with no decoherence is almost 27%. In contrast, the probability to trap an electron with decoherence is 70% at 100 K, 63% at 200 K and 58% at 300 K. Our model provides a novel method of trapping an electron at room temperature.

  14. Polarization Response in InAs Quantum Dots: Theoretical Correlation between Composition and Electronic Properties

    E-Print Network [OSTI]

    Usman, Muhammad; Todaro, Maria Teresa; De Giorgi, Milena; O'Reilly, Eoin P; Klimeck, Gerhard; Passaseo, Adriana

    2012-01-01T23:59:59.000Z

    III-V growth and surface conditions strongly influence the physical structure and resulting optical properties of self-assembled quantum dots (QDs). Beyond the design of a desired active optical wavelength, the polarization response of QDs is of particular interest for optical communications and quantum information science. Previous theoretical studies based on a pure InAs QD model failed to reproduce experimentally observed polarization properties. In this work, multi-million atom simulations are performed to understand the correlation between chemical composition and polarization properties of QDs. A systematic analysis of QD structural parameters leads us to propose a two layer composition model, mimicking In segregation and In-Ga intermixing effects. This model, consistent with mostly accepted compositional findings, allows to accurately fit the experimental PL spectra. The detailed study of QD morphology parameters presented here serves as a tool for using growth dynamics to engineer the strain field ins...

  15. Magnetic relaxation of superconducting quantum dot: two-dimensional false vacuum decay

    E-Print Network [OSTI]

    D. R. Gulevich; F. V. Kusmartsev

    2006-09-11T23:59:59.000Z

    Quantum tunneling of vortices has been found to be an important novel phenomena for description of low temperature creep in high temperature superconductors (HTSCs). We speculate that quantum tunneling may be also exhibited in mesoscopic superconductors due to vortices trapped by the Bean-Livingston barrier. The London approximation and method of images is used to estimate the shape of the potential well in superconducting HTSC quantum dot. To calculate the escape rate we use the instanton technique. We model the vortex by a quantum particle tunneling from a two-dimensional ground state under magnetic field applied in the transverse direction. The resulting decay rates obtained by the instanton approach and conventional WKB are compared revealing complete coincidence with each other.

  16. Tuning the external optical feedback-sensitivity of a passively mode-locked quantum dot laser

    SciTech Connect (OSTI)

    Raghunathan, R., E-mail: raghunat@vt.edu; Kovanis, V.; Lester, L. F. [Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, 302 Whittemore Hall, Blacksburg, Virginia 24061 (United States); Grillot, F. [Télécom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 46 rue Barrault, 75634 Paris Cedex 13 (France); Mee, J. K.; Murrell, D. [Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States)

    2014-07-28T23:59:59.000Z

    The external optical feedback-sensitivity of a two-section, passively mode-locked quantum dot laser operating at elevated temperature is experimentally investigated as a function of absorber bias voltage. Results show that the reverse-bias voltage on the absorber has a direct impact on the damping rate of the free-running relaxation oscillations of the optical signal output, thereby enabling interactive external control over the feedback-response of the device, even under the nearly resonant cavity configuration. The combination of high temperature operation and tunable feedback-sensitivity is highly promising from a technological standpoint, in particular, for applications requiring monolithic integration of multi-component architectures on a single chip in order to accomplish, for instance, the dual-objectives of stable pulse quality and isolation from parasitic reflections.

  17. Epitaxial lift-off of quantum dot enhanced GaAs single junction solar cells

    SciTech Connect (OSTI)

    Bennett, Mitchell F.; Bittner, Zachary S.; Forbes, David V.; Hubbard, Seth M., E-mail: smhsps@rit.edu [Rochester Institute of Technology, Rochester, New York 14623 (United States); Rao Tatavarti, Sudersena; Wibowo, Andree; Pan, Noren; Chern, Kevin [MicroLink Devices, Inc., Niles, Illinois 60714 (United States)] [MicroLink Devices, Inc., Niles, Illinois 60714 (United States); Phillip Ahrenkiel, S. [South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States)] [South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States)

    2013-11-18T23:59:59.000Z

    InAs/GaAs strain-balanced quantum dot (QD) n-i-p solar cells were fabricated by epitaxial lift-off (ELO), creating thin and flexible devices that exhibit an enhanced sub-GaAs bandgap current collection extending into the near infrared. Materials and optical analysis indicates that QD quality after ELO processing is preserved, which is supported by transmission electron microscopy images of the QD superlattice post-ELO. Spectral responsivity measurements depict a broadband resonant cavity enhancement past the GaAs bandedge, which is due to the thinning of the device. Integrated external quantum efficiency shows a QD contribution to the short circuit current density of 0.23?mA/cm{sup 2}.

  18. Electrostatically defined Quantum Dots in a Si/SiGe Heterostructure

    E-Print Network [OSTI]

    A. Wild; J. Sailer; J. Nützel; G. Abstreiter; S. Ludwig; D. Bougeard

    2010-07-14T23:59:59.000Z

    We present an electrostatically defined few-electron double quantum dot (QD) realized in a molecular beam epitaxy grown Si/SiGe heterostructure. Transport and charge spectroscopy with an additional QD as well as pulsed-gate measurements are demonstrated. We discuss technological challenges specific for silicon-based heterostructures and the effect of a comparably large effective electron mass on transport properties and tunability of the double QD. Charge noise, which might be intrinsically induced due to strain-engineering is proven not to affect the stable operation of our device as a spin qubit. Our results promise the suitability of electrostatically defined QDs in Si/SiGe heterostructures for quantum information processing.

  19. Electrostatically defined Quantum Dots in a Si/SiGe Heterostructure

    E-Print Network [OSTI]

    Wild, A; Nützel, J; Abstreiter, G; Ludwig, S; Bougeard, D

    2010-01-01T23:59:59.000Z

    We present an electrostatically defined few-electron double quantum dot (QD) realized in a molecular beam epitaxy grown Si/SiGe heterostructure. Transport and charge spectroscopy with an additional QD as well as pulsed-gate measurements are demonstrated. We discuss technological challenges specific for silicon-based heterostructures and the effect of a comparably large effective electron mass on transport properties and tunability of the double QD. Charge noise, which might be intrinsically induced due to strain-engineering is proven not to affect the stable operation of our device as a spin qubit. Our results promise the suitability of electrostatically defined QDs in Si/SiGe heterostructures for quantum information processing.

  20. Charge Relaxation in a Single Electron Si/SiGe Double Quantum Dot

    E-Print Network [OSTI]

    K. Wang; C. Payette; Y. Dovzhenko; P. W. Deelman; J. R. Petta

    2013-04-15T23:59:59.000Z

    We measure the interdot charge relaxation time T_1 of a single electron trapped in an accumulation mode Si/SiGe double quantum dot. The energy level structure of the charge qubit is determined using photon assisted tunneling, which reveals the presence of a low lying excited state. We systematically measure T_1 as a function of detuning and interdot tunnel coupling and show that it is tunable over four orders of magnitude, with a maximum of 45 microseconds for our device configuration. Measured relaxation times are consistent with a phonon mediated energy relaxation process and indicate that low lying excited states may have important implications in the development of silicon spin qubits.