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  1. Jamie King

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

    jamie king Jamie King Keeping an Eye on Laser Safety Jamie King Jamie King When opportunity knocks, Jamie King jumps up to answer the door. King has parlayed a number of timely job offers into a career at what he considers the "center of the (laser) universe": serving as laser safety officer (LSO) for NIF, and later for all of LLNL. Overseeing laser safety at the world's largest and highest-energy laser facility has required dedicated effort to meet the expectations created by the

  2. King Salmon, Alaska: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. King Salmon is a census-designated place in Bristol Bay Borough, Alaska. It falls under...

  3. Bristol Bay Borough, Alaska: Energy Resources | Open Energy Informatio...

    Open Energy Info (EERE)

    as an ASHRAE 169-2006 Climate Zone Number 7. Places in Bristol Bay Borough, Alaska King Salmon, Alaska Naknek, Alaska South Naknek, Alaska Retrieved from "http:...

  4. Jeremy King | Photosynthetic Antenna Research Center

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

    Jeremy King Jeremy King Jeremy King Graduate Student E-mail: jdking@wustl.edu Website: Washington University Graduate

  5. SOUTHEASTERN FEDERAL POWER ALLIANCE Martin Luther King, Jr. Federal...

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

    Martin Luther King, Jr. Federal Building 77 Forsyth Street SW, Atlanta, GA 30303 November 6, 2014 November 5, 2014: Meet at the Glenn Hotel lobby at 6:00 p.m. to walk to...

  6. King Mountain | Open Energy Information

    Open Energy Info (EERE)

    Mountain Jump to: navigation, search Name King Mountain Facility King Mountain Sector Wind energy Facility Type Commercial Scale Wind Facility Status In Service Owner NextEra...

  7. King_1983.pdf

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

    King County Metro Transit Hybrid Articulated Buses: Interim Evaluation Results K. Chandler Battelle K. Walkowicz National Renewable Energy Laboratory Technical Report NREL/TP-540-39742 April 2006 King County Metro Transit Hybrid Articulated Buses: Interim Evaluation Results K. Chandler Battelle K. Walkowicz National Renewable Energy Laboratory Prepared under Task No. FC06.3000 Technical Report NREL/TP-540-39742 April 2006 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado

  8. Christopher King | Department of Energy

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

    Christopher King About Us Christopher King - Principal Deputy Assistant Secretary Christopher King Christopher King is the Principal Deputy Assistant Secretary for the Office of Congressional and Intergovernmental Affairs at the U.S. Department of Energy. Here he provides strategic advice to the Secretary and Departmental leadership on engagement with the U.S. Congress, state, tribal, city and county governments, other Federal agencies, and key external stakeholders, enhancing the Department's

  9. Alexander H. King, Director

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

    Alexander H. King, Director 134 Wilhelm Hall The Ames Laboratory Ames, IA 50011-3020 alexking@ameslab.gov (515) 296-4500 The Critical Materials Institute, an Energy Innovation Hub created by the U.S. Department of Energy, has a big problem to solve - what would we do without rare earths? Rare earths are a big part of our modern world. They are in clean energy technologies like wind turbines and solar cells, and in many things we use every day - cars, cell phones, computers and televisions. We

  10. Kings River Conservation Dist | Open Energy Information

    Open Energy Info (EERE)

    Kings River Conservation Dist Jump to: navigation, search Name: Kings River Conservation Dist Place: California Phone Number: 559-237-5567 Website: www.krcd.org Facebook: https:...

  11. Polar King: Order (2013-CE-5328)

    Broader source: Energy.gov [DOE]

    DOE ordered Polar King International Inc. to pay a $8,000 civil penalty after finding Polar King had failed to certify that certain models of walk-in cooler and freezer components comply with the applicable energy conservation standards.

  12. Daya Bay

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

    Bay Daya Bay Basics The basics of Daya Bay computing at PDSF. Read More » Data Management All Daya Bay raw data is transferred to PDSF. Read More » File Systems Daya Bay has space on 2 elizas: 6TB on /eliza7 and 35TB on /eliza16. Read More » Running on Carver The Daya Bay software is installed on PDSF on /common so is therefore unavailable on Carver. At this point there has been no effort to port the code to /project for use on... Read More » Last edited: 2016-04-29 11:35:01

  13. NREL Wins Martin Luther King Award

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

    Wins Martin Luther King Award For more information contact: e:mail: Public Affairs Golden, Colo., January 10, 1996 -- The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) has won the Martin Luther King, Jr. Business Social Responsibility Award for its support of minority and women-owned small businesses in Colorado. The annual award recognizes businesses and individuals who best exemplify the life and spirit of Martin Luther King, Jr. and who demonstrate ongoing community

  14. Rev. Martin Luther King, Jr. Commemorative Program

    Broader source: Energy.gov [DOE]

    All employees are invited to the Department’s 2014 Commemorative Program honoring the late Rev. Dr. Martin Luther King, Jr. on January 22, 2014 at 11 am.

  15. City of Kings Mountain, North Carolina (Utility Company) | Open...

    Open Energy Info (EERE)

    Kings Mountain, North Carolina (Utility Company) Jump to: navigation, search Name: City of Kings Mountain Place: North Carolina Phone Number: 704.730.2125 Website:...

  16. Xiamien King Long United Automotive Industry Suzhou | Open Energy...

    Open Energy Info (EERE)

    Xiamien King Long United Automotive Industry Suzhou Jump to: navigation, search Name: Xiamien King Long United Automotive Industry (Suzhou) Place: Suzhou, Fujian Province, China...

  17. King Mountain Wind Ranch I | Open Energy Information

    Open Energy Info (EERE)

    Mountain Wind Ranch I Jump to: navigation, search Name King Mountain Wind Ranch I Facility King Mountain Wind Ranch Sector Wind energy Facility Type Commercial Scale Wind Facility...

  18. City of King Cove, Alaska (Utility Company) | Open Energy Information

    Open Energy Info (EERE)

    King Cove, Alaska (Utility Company) Jump to: navigation, search Name: City of King Cove Place: Alaska Phone Number: (907) 497-2340 Website: www.cityofkingcove.comfinance Outage...

  19. Dr. Martin Luther King Jr. Birthday Celebration

    Broader source: Energy.gov [DOE]

    Today, Dr. King is memorialized on the National Mall where he once spoke, a symbol of how far our Nation has come and a testament to the quiet heroes whose names may never appear in history books,...

  20. Charging Up in King County, Washington

    ScienceCinema (OSTI)

    Constantine, Dow; Oliver, LeAnn; Inslee, Jay; Sahandy, Sheida; Posthuma, Ron; Morrison, David;

    2013-05-29

    King County, Washington is spearheading a regional effort to develop a network of electric vehicle charging stations. It is also improving its vehicle fleet and made significant improvements to a low-income senior housing development.

  1. Charging Up in King County, Washington

    Broader source: Energy.gov [DOE]

    King County, Washington is spearheading a regional effort to develop a network of electric vehicle charging stations. It is also improving its vehicle fleet and made significant improvements to a...

  2. Charging Up in King County, Washington

    SciTech Connect (OSTI)

    Constantine, Dow; Oliver, LeAnn; Inslee, Jay; Sahandy, Sheida; Posthuma, Ron; Morrison, David

    2011-01-01

    King County, Washington is spearheading a regional effort to develop a network of electric vehicle charging stations. It is also improving its vehicle fleet and made significant improvements to a low-income senior housing development.

  3. Polar King: Proposed Penalty (2013-CE-5328)

    Broader source: Energy.gov [DOE]

    DOE alleged in a Notice of Proposed Civil Penalty that Polar King International Inc. failed to certify a variety of walk-in cooler or freezer components as compliant with the applicable energy conservation standards.

  4. DR. MARTIN L. KING, JR. BIRTHDAY CELEBRATION

    Broader source: Energy.gov [DOE]

    The MLK Day of Service is a way to transform Rev. Dr. Martin Luther King, Jr.’s life and teachings into community action that helps solve social problems. Rev. Dr. Martin Luther King, Jr. was a vital figure of the modern era and a pivotal figure in the Civil Rights Movement. His lectures and dialogues stirred the concern and sparked the conscience of a generation.

  5. Paul W. King, Ph.D., M.S. | Bioenergy | NREL

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

    Paul W. King Paul W. King, Ph.D., M.S. Scientist VI - Supervisor, Photobiology Group Paul.King@nrel.gov | 303-384-6277 Research Interests Paul King's research interests are broadly ...

  6. CMI Webinar: Alex King and Stacy Joiner, December 2015 | Critical...

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

    Alex King and Stacy Joiner, December 2015 The CMI webinar on December 9, 2015, featured Alex King and Stacy Joiner discussing the updates to the CMI Affiliate Membership Program...

  7. USDOE's Dr. Martin Luther King, Jr. Commemorative Program

    ScienceCinema (OSTI)

    Secretary Steven Chu; Deputy Secretary Daniel Poneman; Dot Harris; Congressman John Lewis; Clay Middleton; Neile Miller

    2013-02-14

    Video presentation of the Department of Energy?s 2013 commemorative program honoring Dr. Martin Luther King, Jr.

  8. Kings River Conservation District (KRCD) Solar Farm Solar Power...

    Open Energy Info (EERE)

    River Conservation District (KRCD) Solar Farm Solar Power Plant Jump to: navigation, search Name Kings River Conservation District (KRCD) Solar Farm Solar Power Plant Facility...

  9. Kings County, California: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Kings County, California: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 36.0988489, -119.8815203 Show Map Loading map... "minzoom":false,"map...

  10. King Abdulaziz City for Science and Technology | Open Energy...

    Open Energy Info (EERE)

    Abdulaziz City for Science and Technology Jump to: navigation, search Name: King Abdulaziz City for Science and Technology Place: Riyadh, Saudi Arabia Zip: 11442 Sector: Solar...

  11. Hooper Bay Efficiency Feasibility Study

    Office of Environmental Management (EM)

    (OUR PEOPLE) Hooper Bay Energy Efficiency Feasibility ... The name Hooper Bay came into common usage after a post ... BAY IS MARITIME. THE MEAN ANNUAL SNOWFALL IS 75 INCHES ...

  12. DOE - NNSA/NFO -- News & Views Huron King

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

    Huron King Photo - The 'Huron King' six seconds after test detonation. A rare type of Vertical Line of Sight (VLOS) underground test was conducted by the Defense Nuclear Agency on June 24, 1980. The "Huron King" test used a nuclear device of less than 20 kilotons. The VLOS design involved placing the nuclear device at the bottom of the shaft with a communications satellite and other experiments in an above-ground test chamber to simulate a space environment. At zero time, the radiation

  13. Meet CMI Director Alex King | Critical Materials Institute

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

    Director Alex King CMI Director Alex King CMI Director Alex King was born and raised in London. He attended the University of Sheffield as an undergraduate and earned his doctorate from Oxford. He was a postdoc at Oxford and then M.I.T. before joining the faculty at the State University of New York at Stony Brook, where he also served as the Vice Provost for Graduate Studies (Dean of the Graduate School). He was appointed as Professor and Head of the School of Materials Engineering at Purdue in

  14. Beep Beep! King County, Washington Is Charging Up Savings

    Broader source: Energy.gov [DOE]

    King County uses $6.1 million to make investments that dramatically reduce energy waste, improve the quality of life for the residents of an area senior housing community, and lead regional efforts to install electric vehicle charging stations.

  15. Sandia National Laboratories: Dr. King's dream continues to motivate...

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

    grouped together either vertically or horizontally and were velvet hangings or framed art. Most of the cities near me had a Martin Luther King Drive in the black community....

  16. King County Metro Transit Hybrid Articulated Buses: Final Evaluation Results

    SciTech Connect (OSTI)

    Chandler, K.; Walkowicz, K.

    2006-12-01

    Final technical report compares and evaluates new diesel and diesel hybrid-electric articulated buses operated as part of the King County Metro Transit (KC Metro) fleet in Seattle, Washington. The evaluation lasted 12 months.

  17. King of Prussia, Pennsylvania: Energy Resources | Open Energy...

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. King of Prussia is a census-designated place in Montgomery County, Pennsylvania.1...

  18. King and Queen County, Virginia: Energy Resources | Open Energy...

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. King and Queen County is a county in Virginia. Its FIPS County Code is 097. It is classified...

  19. King William County, Virginia: Energy Resources | Open Energy...

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. King William County is a county in Virginia. Its FIPS County Code is 101. It is classified...

  20. King City, Oregon: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. King City is a city in Washington County, Oregon. It falls under Oregon's 1st congressional...

  1. King County, Texas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. King County is a county in Texas. Its FIPS County Code is 269. It is classified as ASHRAE...

  2. King George County, Virginia: Energy Resources | Open Energy...

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. King George County is a county in Virginia. Its FIPS County Code is 099. It is classified as...

  3. Aljazeera story on rare earths features Alex King | The Ames...

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

    Aljazeera story on rare earths features Alex King Aljazeera America recently did a story on the demand and scarcity of rare-earth metals and spoke to Ames Laboratory scientist and...

  4. NREL'S Morgan-Smith Honored by Martin Luther King Commission

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

    ...Smith Honored by Martin Luther King Commission For more information contact: Sarah Holmes Barba, 303-275-3023 email: Sarah Barba Golden, Colo., Jan. 9, 2001 - Syl Morgan-Smith, ...

  5. Honoring the Legacy of Martin Luther King Jr. | Department of Energy

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

    the Legacy of Martin Luther King Jr. Honoring the Legacy of Martin Luther King Jr. January 19, 2012 - 1:32pm Addthis Honoring the Legacy of Martin Luther King Jr. Karissa Marcum Public Affairs Specialist, Office of Public Affairs Employees across the Department honored Dr. Martin Luther King Jr. on Tuesday, saluting the civil rights legend during a lively ceremony at Department headquarters. Secretary Chu joined Lynn Cothren, former personal assistant to Coretta Scott King, and Reverend C.T.

  6. King County Metro Transit Hybrid Articulated Buses: Interim Evaluation Results

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

    King County Metro Transit Hybrid Articulated Buses: Interim Evaluation Results K. Chandler Battelle K. Walkowicz National Renewable Energy Laboratory Technical Report NREL/TP-540-39742 April 2006 King County Metro Transit Hybrid Articulated Buses: Interim Evaluation Results K. Chandler Battelle K. Walkowicz National Renewable Energy Laboratory Prepared under Task No. FC06.3000 Technical Report NREL/TP-540-39742 April 2006 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado

  7. King County Metro Transit Hybrid Articulated Buses: Final Evaluation Results

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

    King County Metro Transit Hybrid Articulated Buses: Final Evaluation Results K. Chandler Battelle K. Walkowicz National Renewable Energy Laboratory Technical Report NREL/TP-540-40585 December 2006 NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 King County Metro Transit Hybrid Articulated Buses: Final Evaluation Results K. Chandler Battelle K. Walkowicz National Renewable Energy Laboratory Prepared under Task No. FC07.3000 Technical Report

  8. Bay Area | Open Energy Information

    Open Energy Info (EERE)

    Page Edit History Bay Area Jump to: navigation, search Contents 1 Clean Energy Clusters in the Bay Area 1.1 Products and Services in the Bay Area 1.2 Research and Development...

  9. Upholding Dr. King's Dream and Inspiring the Next Generation Through STEM

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

    Education | Department of Energy Upholding Dr. King's Dream and Inspiring the Next Generation Through STEM Education Upholding Dr. King's Dream and Inspiring the Next Generation Through STEM Education January 27, 2015 - 12:56pm Addthis Upholding Dr. King’s Dream and Inspiring the Next Generation Through STEM Education Joshua Sneideman Joshua Sneideman Albert Einstein Distinguished Educator Fellow According to the Reverend Dr. Martin Luther King, Jr., "The function of education is

  10. Chesapeake Bay Test Site | Open Energy Information

    Open Energy Info (EERE)

    Chesapeake Bay Test Site Jump to: navigation, search Name Chesapeake Bay Test Site Facility Chesapeake Bay Test Site Sector Wind energy Facility Type Offshore Wind Facility Status...

  11. Module bay with directed flow

    DOE Patents [OSTI]

    Torczynski, John R.

    2001-02-27

    A module bay requires less cleanroom airflow. A shaped gas inlet passage can allow cleanroom air into the module bay with flow velocity preferentially directed toward contaminant rich portions of a processing module in the module bay. Preferential gas flow direction can more efficiently purge contaminants from appropriate portions of the module bay, allowing a reduced cleanroom air flow rate for contaminant removal. A shelf extending from an air inlet slit in one wall of a module bay can direct air flowing therethrough toward contaminant-rich portions of the module bay, such as a junction between a lid and base of a processing module.

  12. Microsoft Word - CPV10 King HCPV Characterization-final.docx

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

    HCPV Characterization: Analysis of Fielded System Data Bruce King 1 , Dan Riley 1 , Clifford Hansen 1 , Matt Erdman 1 , John Gabriel 2 and Kanchan Ghosal 2 1 Sandia National Laboratories, Albuquerque, NM 81785, USA 2 Semprius, Inc., 4915 Prospectus Drive, Suite C, Durham, NC 27713, USA Abstract. Sandia and Semprius have partnered to evaluate the operational performance of a 3.5 kW (nominal) R&D system using 40 Semprius modules. Eight months of operational data has been collected and

  13. J. R. King, C. R. Sovinec, and V. V. Mirnov

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

    fluid modeling of tearing and relaxation in a plasma pinch J. R. King, C. R. Sovinec, and V. V. Mirnov Citation: Phys. Plasmas 19, 055905 (2012); doi: 10.1063/1.3695346 View online: http://dx.doi.org/10.1063/1.3695346 View Table of Contents: http://pop.aip.org/resource/1/PHPAEN/v19/i5 Published by the American Institute of Physics. Additional information on Phys. Plasmas Journal Homepage: http://pop.aip.org/ Journal Information: http://pop.aip.org/about/about_the_journal Top downloads:

  14. J. R. King, C. R. Sovinec, and V. V. Mirnov

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

    effects on magnetic tearing in pinch configurations J. R. King, C. R. Sovinec, and V. V. Mirnov Citation: Phys. Plasmas 18, 042303 (2011); doi: 10.1063/1.3571599 View online: http://dx.doi.org/10.1063/1.3571599 View Table of Contents: http://pop.aip.org/resource/1/PHPAEN/v18/i4 Published by the American Institute of Physics. Additional information on Phys. Plasmas Journal Homepage: http://pop.aip.org/ Journal Information: http://pop.aip.org/about/about_the_journal Top downloads:

  15. EECBG Success Story: Beep Beep! King County, Washington Is Charging Up Savings

    Broader source: Energy.gov [DOE]

    Residents of King County, Washington, are seeing several improvements in their community thanks to a $6.1 million Energy Efficiency and Conservation Block Grant (EECBG). The grant has allowed King County to conduct a variety of public and commercial energy efficiency upgrades, including the installation of electric vehicle charging stations, county vehicle fleet upgrades and senior housing energy improvements. Learn more.

  16. Field's Point Wastewater Treatment Facility (Narragansett Bay...

    Open Energy Info (EERE)

    Field's Point Wastewater Treatment Facility (Narragansett Bay Commission) Jump to: navigation, search Name Field's Point Wastewater Treatment Facility (Narragansett Bay Commission)...

  17. Bay Biodiesel LLC | Open Energy Information

    Open Energy Info (EERE)

    Biodiesel LLC Jump to: navigation, search Name: Bay Biodiesel LLC Place: Martinez, California Zip: 94553 Product: Biodiesel producers in Martinez, California. References: Bay...

  18. Bay Solar Power Design | Open Energy Information

    Open Energy Info (EERE)

    Solar Power Design Jump to: navigation, search Name: Bay Solar Power Design Place: California Product: US-based PV system installer. References: Bay Solar Power Design1 This...

  19. Synchronization and an application of a novel fractional order King Cobra chaotic system

    SciTech Connect (OSTI)

    Muthukumar, P. Balasubramaniam, P.; Ratnavelu, K.

    2014-09-01

    In this paper, we design a new three dimensional King Cobra face shaped fractional order chaotic system. The multi-scale synchronization scheme of two fractional order chaotic systems is described. The necessary conditions for the multi-scale synchronization of two identical fractional order King Cobra chaotic systems are derived through feedback control. A new cryptosystem is proposed for an image encryption and decryption by using synchronized fractional order King Cobra chaotic systems with the supports of multiple cryptographic assumptions. The security of the proposed cryptosystem is analyzed by the well known algebraic attacks. Numerical simulations are given to show the effectiveness of the proposed theoretical results.

  20. King County Metro Transit Hybrid Articulated Transit Buses: Interim Evaluation Results

    SciTech Connect (OSTI)

    Chandler, K.; Walkowicz, K.

    2006-04-01

    Interim technical report compares and evaluates new diesel and diesel hybrid-electric articulated buses operated as part of the King County Metro Transit (KC Metro) fleet in Seattle, Washington.

  1. Radiological Risk Assessment for King County Wastewater Treatment Division

    SciTech Connect (OSTI)

    Strom, Daniel J.

    2005-08-05

    Staff of the King County Wastewater Treatment Division (WTD) have concern about the aftermath of a radiological dispersion event (RDE) leading to the introduction of significant quantities of radioactive material into the combined sanitary and storm sewer system in King County, Washington. Radioactive material could come from the use of a radiological dispersion device (RDD). RDDs include "dirty bombs" that are not nuclear detonations but are explosives designed to spread radioactive material (National Council on Radiation Protection and Measurements (NCRP) 2001). Radioactive material also could come from deliberate introduction or dispersion of radioactive material into the environment, including waterways and water supply systems. This document develops plausible and/or likely scenarios, including the identification of likely radioactive materials and quantities of those radioactive materials to be involved. These include 60Co, 90Sr, 137Cs, 192Ir, 226Ra, plutonium, and 241Am. Two broad categories of scenarios are considered. The first category includes events that may be suspected from the outset, such as an explosion of a "dirty bomb" in downtown Seattle. The explosion would most likely be heard, but the type of explosion (e.g., sewer methane gas or RDD) may not be immediately known. Emergency first responders must be able to quickly detect the radioisotopes previously listed, assess the situation, and deploy a response to contain and mitigate (if possible) detrimental effects resulting from the incident. In such scenarios, advance notice of about an hour or two might be available before any contaminated wastewater reaches a treatment plant. The second category includes events that could go initially undetected by emergency personnel. Examples of such a scenario would be the inadvertent or surreptitious introduction of radioactive material into the sewer system. Intact rogue radioactive sources from industrial radiography devices, well-logging apparatus, or

  2. Tular Lake Field, Kings County, California - a significant onshore development

    SciTech Connect (OSTI)

    Lindblom, R.G.; Waldron, J.M.

    1985-04-01

    The Tulare Lake field is located in Kings County, California, on the west side of the San Joaquin Valley and 10 mi east of the Kettleman Hills (North Dome) field and 30 mi souuheast of the city of Coalinga. The field was discovered by Husky Oil Co. (Marathon) in October 1981 with the completion of the Boswell 22-16, Sec. 16, T22S, R20E from sands in the Burbank formation of Oligocene geologic age. Chevron USA offset the Husky discovery well with the completion of the Salyer 678X, Sec. 8, T22S, R20E, in May 1983. Both Chevron and Husky have continued an orderly development of the field, and to date Chevron has 9 producing wells and Husky 10 producing wells. Production is found in the Burbank formation at a vertical depth below 12,800 ft. The entrapment of hydrocarbons is caused by a low amplitude, seismically subtle, anticlinal fold trending northwest/southeast. Isochore maps of the Burbank formation show that stratigraphy is important in the distribution of the four producing sand intervals. Oil gravities form the sands vary 39/sup 0/ API to 51/sup 0/ API and the GOR ranges from 1050 to over 5500. As of January 1, 1984, the field has a cumulative production of 1.7 million bbl of oil and 3.5 billion ft/sup 3/ of gas.

  3. EA-389 Greay Bay Energy VI, LLC | Department of Energy

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

    Order authorizing Great Bay Energy to export electric energy to Canada. EA-389 Great Bay ... Great Bay Energy VI, LLC EA-389-A Great Bay Energy VI, LLC EA-342-A Royal Bank of Canada

  4. Felton Bay Logistics, LLC | Open Energy Information

    Open Energy Info (EERE)

    Logistics, LLC1 This article is a stub. You can help OpenEI by expanding it. Felton Bay Logistics, LLC is a company based in San Diego, California. Felton Bay offers training,...

  5. BayWa Group | Open Energy Information

    Open Energy Info (EERE)

    BayWa Group Jump to: navigation, search Name: BayWa Group Place: Munich, Germany Zip: 81925 Sector: Services, Solar Product: Germany-based company with international operations...

  6. Tuscola Bay Wind | Open Energy Information

    Open Energy Info (EERE)

    Jump to: navigation, search Name Tuscola Bay Wind Facility Tuscola Bay Wind Sector Wind energy Facility Type Commercial Scale Wind Facility Status In Service Owner NextEra Energy...

  7. CMI Webinar: Alex King, August 2016, part 1 | Critical Materials Institute

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

    CMI Webinar: Alex King, August 2016, part 1 CMI Director Alex King presented on "CMI Director's Perspective" on August 23, 2016. The full webinar ran more than an hour; the archive is available in five files of 8 to 14 minutes each. This first part runs 12:05. Here are links to the second part, third part, fourth part, fifth part, and the sixth part. The CMI Webinar series is organized by the CMI education and outreach team at Colorado School of Mines. Additional information about CMI

  8. bayesPicture.jpg | OSTI, US Dept of Energy Office of Scientific and

    Office of Scientific and Technical Information (OSTI)

    Technical Information bayesPicture

  9. Radiological Instrumentation Assessment for King County Wastewater Treatment Division

    SciTech Connect (OSTI)

    Strom, Daniel J.; McConn, Ronald J.; Brodzinski, Ronald L.

    2005-05-19

    The King County Wastewater Treatment Division (WTD) have concern about the aftermath of a radiological dispersion event (RDE) leading to the introduction of significant quantities of radioactive material into its combined sanitary and storm sewer system. Radioactive material could come from the use of a radiological dispersion device (RDD). RDDs include "dirty bombs" that are not nuclear detonations but are explosives designed to spread radioactive material. Radioactive material also could come from deliberate introduction or dispersion of radioactive material into the environment, including waterways and water supply systems. Volume 2 of PNNL-15163 assesses the radiological instrumentation needs for detection of radiological or nuclear terrorism, in support of decisions to treat contaminated wastewater or to bypass the West Point Treatment Plant (WPTP), and in support of radiation protection of the workforce, the public, and the infrastructure of the WPTP. Fixed radiation detection instrumentation should be deployed in a defense-in-depth system that provides 1) early warning of significant radioactive material on the way to the WPTP, including identification of the radionuclide(s) and estimates of the soluble concentrations, with a floating detector located in the wet well at the Interbay Pump Station and telemetered via the internet to all authorized locations; 2) monitoring at strategic locations within the plant, including 2a) the pipe beyond the hydraulic ram in the bar screen room; 2b) above the collection funnels in the fine grit facility; 2c) in the sampling tank in the raw sewage pump room; and 2d) downstream of the concentration facilities that produce 6% blended and concentrated biosolids. Engineering challenges exist for these applications. It is necessary to deploy both ultra-sensitive detectors to provide early warning and identification and detectors capable of functioning in high-dose rate environments that are likely under some scenarios, capable

  10. CMI Webinar: Alex King, August 2016, part 2 | Critical Materials Institute

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

    2 CMI Director Alex King presented on "CMI Director's Perspective" on August 23, 2016. The full webinar ran more than an hour; the archive is available in five files of 8 to 14 minutes each. This second part runs 10:36. Here are links to the first part, third

  11. CMI Webinar: Alex King, August 2016, part 3 | Critical Materials Institute

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

    3 CMI Director Alex King presented on "CMI Director's Perspective" on August 23, 2016. The full webinar ran more than an hour; the archive is available in five files of 8 to 14 minutes each. This third part runs 8:30. Here are links to the first part, second

  12. CMI Webinar: Alex King, August 2016, part 4 | Critical Materials Institute

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

    4 CMI Director Alex King presented on "CMI Director's Perspective" on August 23, 2016. The full webinar ran more than an hour; the archive is available in five files of 8 to 14 minutes each. This fourth part runs 14:08. Here are links to the first part, second part, third

  13. CMI Webinar: Alex King, August 2016, part 5 | Critical Materials Institute

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

    5 CMI Director Alex King presented on "CMI Director's Perspective" on August 23, 2016. The full webinar ran more than an hour; the archive is available in five files of 8 to 14 minutes each. This fifth part runs 9:19. Here are links to the first part, second part, third part, fourth

  14. CMI Webinar: Alex King, August 2016, part 6 | Critical Materials Institute

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

    6 CMI Director Alex King presented on "CMI Director's Perspective" on August 23, 2016. The full webinar ran more than an hour; the archive is available in five files of 8 to 14 minutes each. This sixth part runs 9:50. Here are links to the first part, second part, third part, fourth part, and the fifth

  15. Keweenaw Bay Indian Community Presentation

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

    - Keweenaw Bay Indian Community PRESENTATION Assessing the Feasibility of Renewable Energy Development and Energy Efficiency Deployment on Tribal Lands DOE Tribal Energy Program Review October 25 29, 2010 Gregg Nominelli, J.D. Economic Developer BACKGROUND INFORMATION  U.S. Department of Justice - Community Capacity Development Office  Alternative & Renewable Energy Committee Established by Tribal Council  Council for Energy Resource Tribes (CERT) - Developed Strategic Energy Plan

  16. Bay Area | National Nuclear Security Administration

    National Nuclear Security Administration (NNSA)

    Bay Area San Francisco Bay Area Aerial Radiation Assessment Survey (SAN JOSE and SAN FRANCISCO, California) - A helicopter may be seen flying at low altitudes over portions of the San Francisco Bay Area from January 29 through February 6, 2016. The purpose of the flyovers is to measure naturally occurring background radiation. Officials from the National Nuclear... NNSA to Conduct Aerial Radiological Surveys Over San Francisco, Pacifica, Berkeley, And Oakland, CA Areas A U.S. Department of

  17. Hooper Bay Wind Farm | Open Energy Information

    Open Energy Info (EERE)

    Alaska Village Electric Coop (AVEC) Developer Alaska Village Electric Coop (AVEC) Energy Purchaser Alaska Village Electric Coop (AVEC) Location Hooper Bay AK Coordinates...

  18. Bay Front Biomass Facility | Open Energy Information

    Open Energy Info (EERE)

    NEEDS 2006 Database Retrieved from "http:en.openei.orgwindex.php?titleBayFrontBiomassFacility&oldid397174" Feedback Contact needs updating Image needs updating...

  19. Glacier Bay Inc | Open Energy Information

    Open Energy Info (EERE)

    search Name: Glacier Bay Inc Place: Oakland, California Zip: 94601 Product: US-based, advanced thermal control, sound reduction, and DC power management technologies...

  20. Massachusetts Bay Transportation Authority | Open Energy Information

    Open Energy Info (EERE)

    Authority Name: Massachusetts Bay Transportation Authority Address: 10 Park Plaza, Suite 3910 Boston, MA 02116 Zip: 02116 Website: www.mbta.com Coordinates:...

  1. Near Fish Bay Geothermal Area | Open Energy Information

    Open Energy Info (EERE)

    Near Fish Bay Geothermal Area Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Near Fish Bay Geothermal Area Contents 1 Area Overview 2 History and Infrastructure 3...

  2. Tampa Bay Area Ethanol Consortium | Open Energy Information

    Open Energy Info (EERE)

    Bay Area Ethanol Consortium Jump to: navigation, search Name: Tampa Bay Area Ethanol Consortium Place: Tampa, Florida Sector: Biomass Product: Consortium researching ethanol from...

  3. San Francisco Bay Conservation and Development Commission | Open...

    Open Energy Info (EERE)

    Conservation and Development Commission Jump to: navigation, search Logo: San Francisco Bay Conservation and Development Commission Name: San Francisco Bay Conservation and...

  4. Pedro Bay Village Council (Utility Company) | Open Energy Information

    Open Energy Info (EERE)

    Pedro Bay Village Council (Utility Company) Jump to: navigation, search Name: Pedro Bay Village Council Place: Alaska Phone Number: (907) 850-2225 Website: www.swamc.orghtml...

  5. Bay Resource Management Center Biomass Facility | Open Energy...

    Open Energy Info (EERE)

    Resource Management Center Biomass Facility Jump to: navigation, search Name Bay Resource Management Center Biomass Facility Facility Bay Resource Management Center Sector Biomass...

  6. Doe Bay Village Resort Pool & Spa Low Temperature Geothermal...

    Open Energy Info (EERE)

    Doe Bay Village Resort Pool & Spa Low Temperature Geothermal Facility Jump to: navigation, search Name Doe Bay Village Resort Pool & Spa Low Temperature Geothermal Facility...

  7. Cold Bay Hot Spring Geothermal Area | Open Energy Information

    Open Energy Info (EERE)

    Cold Bay Hot Spring Geothermal Area Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Cold Bay Hot Spring Geothermal Area Contents 1 Area Overview 2 History and...

  8. San Luis Bay Estates Pool & Spa Low Temperature Geothermal Facility...

    Open Energy Info (EERE)

    Estates Pool & Spa Low Temperature Geothermal Facility Jump to: navigation, search Name San Luis Bay Estates Pool & Spa Low Temperature Geothermal Facility Facility San Luis Bay...

  9. Microsoft Word - Chemetall Foote_Kings Mountain and Silver Peak Final EA 9-15-10-1 _3_

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

    5 Final Environmental Assessment For Chemetall Foote Corporation Electric Drive Vehicle Battery and Component Manufacturing Initiative Kings Mountain, NC and Silver Peak, NV September 2010 Prepared for: Department of Energy National Energy Technology Laboratory This page intentionally left blank. Electric Drive Vehicle Battery and DOE/EA-1715 Component Manufacturing Initiative Project Environmental Assessment Chemetall Foote Corporation, Kings Mountain, NC and Silver Peak, NV September 2010

  10. Contacts: Alex King, Director, Critical Materials Institute, (515) 296-4505

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

    Five Critical Materials Institute researchers named Most Influential Scientific Minds of 2014 Contacts: Alex King, Director, Critical Materials Institute, (515) 296-4505 Laura Millsaps, Public Affairs, Ames Laboratory, (515) 294-3474 Five physicists who conduct research for the Critical Materials Institute, a U.S. Department of Energy Innovation Hub, have been named to the Thomson Reuters Most Influential Scientific Minds of 2014. They are:  Sergey Bud'ko, Ames Laboratory and Iowa State

  11. New and Underutilized Technology: High Bay LED Lighting

    Broader source: Energy.gov [DOE]

    The following information outlines key deployment considerations for high bay LED lighting within the Federal sector.

  12. General Atomics (GA) | Princeton Plasma Physics Lab

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

    General Atomics (GA) Subscribe to RSS - General Atomics (GA) General Atomics Image: General Atomics (GA) The Scorpion's Strategy: "Catch and Subdue" Read more about The Scorpion's...

  13. Keweenaw Bay Indian Community- 2010 Wind Project

    Office of Energy Efficiency and Renewable Energy (EERE)

    The Keweenaw Bay Indian Community (KBIC) is committed to preserving our natural environment and reducing the amount of fossil fuels consumed while developing "green" business manufacturing jobs on tribal lands.

  14. Keweenaw Bay Indian Community- 2010 Project

    Broader source: Energy.gov [DOE]

    The Keweenaw Bay Indian Community (KBIC) is committed to preserving our natural environment and reducing the amount of fossil fuels consumed while developing "green" business manufacturing jobs on tribal lands.

  15. SCHEDULE: Bay Area Maker Faire 2016

    Broader source: Energy.gov [DOE]

    Find out where and when to meet some of our top innovators and explore the technologies on display from the Department of Energy at the 11th annual Bay Area Maker Faire.

  16. Really Off the Grid: Hooper Bay, AK

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

    Really Off the Grid - Hooper Bay, AK Old Housing - Energy Efficiency Vintage Hooper Bay Renewable Energy - Before & After DOE Tribal Energy Grant * $200,000 - Energy Efficiency Feasibility Study * Hire & train 2-5 local energy assessors * Energy audits of 24 homes with blower doors, etc. - Reduce energy consumption from air leakage - Moisture/mold issues - Reduce drafts * $7/gallon heating fuel * ~ $0.55/kWh - electricity (over half of households behind on utility payments) Is your house

  17. Keeping comets and asteroids at bay

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

    Keeping Comets And Asteroids At Bay Community Connections: Your link to news and opportunities from Los Alamos National Laboratory Latest Issue: September 1, 2016 all issues All Issues » submit Keeping comets and asteroids at bay Every two years, experts from around the globe convene at the Planetary Defense Conference. August 1, 2012 dummy image Read our archives Contacts Editor Linda Anderman Email Community Programs Office Kurt Steinhaus Email Every two years, experts from around the globe

  18. Gradient Analysis and Classification of Carolina Bay Vegetation: A Framework for Bay Wetlands Conservation and Restoration

    SciTech Connect (OSTI)

    Diane De Steven,Ph.D.; Maureen Tone,PhD.

    1997-10-01

    This report address four project objectives: (1) Gradient model of Carolina bay vegetation on the SRS--The authors use ordination analyses to identify environmental and landscape factors that are correlated with vegetation composition. Significant factors can provide a framework for site-based conservation of existing diversity, and they may also be useful site predictors for potential vegetation in bay restorations. (2) Regional analysis of Carolina bay vegetation diversity--They expand the ordination analyses to assess the degree to which SRS bays encompass the range of vegetation diversity found in the regional landscape of South Carolina's western Upper Coastal Plain. Such comparisons can indicate floristic status relative to regional potentials and identify missing species or community elements that might be re-introduced or restored. (3) Classification of vegetation communities in Upper Coastal Plain bays--They use cluster analysis to identify plant community-types at the regional scale, and explore how this classification may be functional with respect to significant environmental and landscape factors. An environmentally-based classification at the whole-bay level can provide a system of templates for managing bays as individual units and for restoring bays to desired plant communities. (4) Qualitative model for bay vegetation dynamics--They analyze present-day vegetation in relation to historic land uses and disturbances. The distinctive history of SRS bays provides the possibility of assessing pathways of post-disturbance succession. They attempt to develop a coarse-scale model of vegetation shifts in response to changing site factors; such qualitative models can provide a basis for suggesting management interventions that may be needed to maintain desired vegetation in protected or restored bays.

  19. Summary of Test Results for Daya Bay Rock Samples (Technical...

    Office of Scientific and Technical Information (OSTI)

    Summary of Test Results for Daya Bay Rock Samples Citation Details In-Document Search Title: Summary of Test Results for Daya Bay Rock Samples You are accessing a document from ...

  20. Summary of Test Results for Daya Bay Rock Samples (Technical...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Summary of Test Results for Daya Bay Rock Samples Citation Details In-Document Search Title: Summary of Test Results for Daya Bay Rock Samples A series of ...

  1. Galveston Bay Biodiesel LP GBB | Open Energy Information

    Open Energy Info (EERE)

    Galveston Bay Biodiesel LP GBB Jump to: navigation, search Name: Galveston Bay Biodiesel LP (GBB) Place: Houston, Texas Product: Developer of a 75.8m litre per year biodiesel...

  2. Bay County, Michigan: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    is classified as ASHRAE 169-2006 Climate Zone Number 5 Climate Zone Subtype A. Registered Energy Companies in Bay County, Michigan Dow Chemical Co Dow Kokam Places in Bay County,...

  3. Bristol Bay Native Corporation- 2003 Project

    Broader source: Energy.gov [DOE]

    Bristol Bay Native Corporation (BBNC), through its subsidiary, Bristol Environmental and Engineering Services Corporation, will assess renewable energy opportunities within the BBNC region of southwest Alaska. The goals of this initiative are to encourage tribal self-sufficiency, create jobs, improve environmental quality, and help make our nation more secure through the development of clean, affordable, and reliable renewable energy technologies. The study will identify technologies or systems that could potentially reduce the cost or improve the sustainability of electricity within the Bristol Bay region.

  4. Salmon Supplementation Studies in Idaho Rivers; Field Activities Conducted on Clear and Pete King Creeks, 2001 Annual Report.

    SciTech Connect (OSTI)

    Gass, Carrie; Olson, Jim M.

    2004-11-01

    In 2001 the Idaho Fisheries Resource Office continued as a cooperator on the Salmon Supplementation Studies in Idaho Rivers (ISS) project on Pete King and Clear creeks. Data relating to supplementation treatment releases, juvenile sampling, juvenile PIT tagging, brood stock spawning and rearing, spawning ground surveys, and snorkel surveys were used to evaluate project data points and augment past data. Due to low adult spring Chinook returns to Kooskia National Fish Hatchery (KNFH) in brood year 1999 there was no smolt supplementation treatment release into Clear Creek in 2001. A 17,014 spring Chinook parr supplementation treatment (containing 1000 PIT tags) was released into Pete King Creek on July 24, 2001. On Clear Creek, there were 412 naturally produced spring Chinook parr PIT tagged and released. Using juvenile collection methods, Idaho Fisheries Resource Office staff PIT tagged and released 320 naturally produced spring Chinook pre-smolts on Clear Creek, and 16 natural pre-smolts on Pete King Creek, for minimum survival estimates to Lower Granite Dam. There were no PIT tag detections of brood year 1999 smolts from Clear or Pete King creeks. A total of 2261 adult spring Chinook were collected at KNFH. Forty-three females were used for supplementation brood stock, and 45 supplementation (ventral fin-clip), and 45 natural (unmarked) adults were released upstream of KNFH to spawn naturally. Spatial and temporal distribution of 37 adults released above the KNFH weir was determined through the use of radio telemetry. On Clear Creek, a total of 166 redds (8.2 redds/km) were observed and data was collected from 195 carcasses. Seventeen completed redds (2.1 redds/km) were found, and data was collected data from six carcasses on Pete King Creek.

  5. Investigation of the GaN-on-GaAs interface for vertical power device applications

    SciTech Connect (OSTI)

    Mreke, Janina Uren, Michael J.; Kuball, Martin; Novikov, Sergei V.; Foxon, C. Thomas; Hosseini Vajargah, Shahrzad; Wallis, David J.; Humphreys, Colin J.; Haigh, Sarah J.; Al-Khalidi, Abdullah; Wasige, Edward; Thayne, Iain

    2014-07-07

    GaN layers were grown onto (111) GaAs by molecular beam epitaxy. Minimal band offset between the conduction bands for GaN and GaAs materials has been suggested in the literature raising the possibility of using GaN-on-GaAs for vertical power device applications. I-V and C-V measurements of the GaN/GaAs heterostructures however yielded a rectifying junction, even when both sides of the junction were heavily doped with an n-type dopant. Transmission electron microscopy analysis further confirmed the challenge in creating a GaN/GaAs Ohmic interface by showing a large density of dislocations in the GaN layer and suggesting roughening of the GaN/GaAs interface due to etching of the GaAs by the nitrogen plasma, diffusion of nitrogen or melting of Ga into the GaAs substrate.

  6. Responses of upland herpetofauna to the restoration of Carolina Bays and thinning of forested Bay Margins.

    SciTech Connect (OSTI)

    Ledvina, Joseph A.

    2008-05-01

    Research on the effects of wetland restoration on reptiles and amphibians is becoming more common, but almost all of these studies have observed the colonization of recently disturbed habitats that were completely dry at the time of restoration. In a similar manner, investigations herpetofaunal responses to forest management have focused on clearcuts, and less intensive stand manipulations are not as well studied. To evaluate community and population responses of reptiles and amphibians to hydrology restoration and canopy removal in the interior of previously degraded Carolina bays, I monitored herpetofauna in the uplands adjacent to six historically degraded Carolina bays at the Savannah River Site (SRS) in South Carolina for four years after restoration. To evaluate the effects of forest thinning on upland herpetofauna, forests were thinned in the margins of three of these bays. I used repeated measures ANOVA to compare species richness and diversity and the abundance of selected species and guilds between these bays and with those at three reference bays that were not historically drained and three control bays that remained degraded. I also used Non-metric Multidimensional Scaling (NMDS) to look for community-level patterns based treatments.

  7. Reconnaissance survey of eight bays in Puget Sound

    SciTech Connect (OSTI)

    Strand, J.A.; Crecelius, E.A.; Pearson, W.H.; Fellingham, G.W.; Elston, R.E.

    1988-03-01

    From 1983 to 1985, Battelle/Marine Research Laboratory conducted reconnaissance-level field and laboratory studies to better characterize toxic contamination problems occurring in selected urban-industrialized bays (Bellingham Bay, Port Gardner - Everett Harbor, Fourmile Rock - Elliot Bay dump site vicinity, Sinclair Inlet) of Puget Sound. It was envisioned that this goal was best achieved by simultaneously determining levels of contamination in selected baseline or 'reference bays' (Samish Bay, Case Inlet, Dabob Bay, Sequim Bay). Two major tasks composed this effort. The first was conducted in 1983 and consisted of preliminary or screening surveys to collect and analyze sediment samples from 101 stations distributed in the four urban-industrialized bays (Figure 1), and at 80 stations distributed in the four baseline bays (Figure 2). The second task was undertaken in 1984 and involved detailed surveys and analyses of the same bays, but at a limited number of stations (32 in urban embayments, 16 in baseline bays). The stations to be resampled in 1984 were the ''cleanest'' of the clean and the ''dirtiest'' of the dirty as determined by the 1983 sediment chemical analyses, and within restrictions imposed by sediment type.

  8. GA SNC Solar | Open Energy Information

    Open Energy Info (EERE)

    GA-SNC Solar Place: Nevada Sector: Solar Product: Nevada-based PV project developer and joint venture of GA-Solar North America and Sierra Nevada Corp. References: GA-SNC...

  9. GaInNAs laser gain

    SciTech Connect (OSTI)

    CHOW,WENG W.; JONES,ERIC D.; MODINE,NORMAND A.; KURTZ,STEVEN R.; ALLERMAN,ANDREW A.

    2000-05-23

    The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of the lasing threshold current density of GaInNAs/GaAs quantum well structures.

  10. Covered Product Category: Industrial Luminaires (High/Low Bay) | Department

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

    of Energy Industrial Luminaires (High/Low Bay) Covered Product Category: Industrial Luminaires (High/Low Bay) The Federal Energy Management Program (FEMP) provides acquisition guidance and Federal efficiency requirements for Industrial Luminaires (High/Low Bay). Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law. Meeting Energy Efficiency Requirements for Industrial

  11. San Francisco Bay Area Aerial Radiation Assessment Survey | National...

    National Nuclear Security Administration (NNSA)

    Visit www.nnsa.energy.gov for more information. Related Topics Bay Area California ... business leaders dedicate Livermore Solar Center Sandia's California site invites ...

  12. MHK Projects/Kachemak Bay Tidal Energy Project | Open Energy...

    Open Energy Info (EERE)

    Kachemak Bay Tidal Energy Project < MHK Projects Jump to: navigation, search << Return to the MHK database homepage Loading map... "minzoom":false,"mappingservice":"googlemaps3","...

  13. Ecological Forecasting in Chesapeake Bay: Using a Mechanistic...

    Office of Scientific and Technical Information (OSTI)

    oxygen, and the likelihood of encountering several noxious species, including harmful algal blooms and water-borne pathogens, for the purpose of monitoring the Bay's ecosystem. ...

  14. 9 Cool Technologies at the Bay Area Maker Faire

    Broader source: Energy.gov [DOE]

    Get a glimpse of some of the technologies from our National Labs in the Make | ENERGY Pavilion at the Bay Area Maker Faire. You can look AND touch.

  15. Bay Harbor Islands, Florida: Energy Resources | Open Energy Informatio...

    Open Energy Info (EERE)

    Bay Harbor Islands is a town in Miami-Dade County, Florida. It falls under Florida's 20th congressional district.12 References US Census Bureau Incorporated place and...

  16. McKay Bay Facility Biomass Facility | Open Energy Information

    Open Energy Info (EERE)

    Biomass Facility Facility McKay Bay Facility Sector Biomass Facility Type Municipal Solid Waste Location Hillsborough County, Florida Coordinates 27.9903597, -82.3017728...

  17. EIS-0494: Excelerate Liquefaction Solutions Lavaca Bay LNG Project...

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

    gas from existing pipeline systems to the LNG terminal facilities. EIS-0494: Excelerate Liquefaction Solutions Lavaca Bay LNG Project Public Comment Opportunities No public ...

  18. Bay Mills Indian Community Energy Reduction Feasibility Study

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

    Tribal Council of Michigan, Inc. Environmental Services Division Chris Kushman Bay Mills Indian Community Energy Reduction Feasibility Study *DOE Tribal Energy Program *Tribal ...

  19. Kawela Bay, Hawaii: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Kawela Bay, Hawaii: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 21.7033333, -158.01 Show Map Loading map... "minzoom":false,"mappingservice...

  20. Promising Technology: High Bay Light-Emitting Diodes

    Broader source: Energy.gov [DOE]

    High bay LEDs offer several advantages over conventional high intensity discharge (HID) luminaires including longer lifetimes, reduced maintenance costs, and lower energy consumption.

  1. Keweenaw Bay Indian Community: 'First Steps' Toward Tribal Weatherizat...

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

    Keweenaw Bay Indian Community 'First Steps' Toward Tribal Weatherization Human Capacity Building Denver, CO - October 29 th , 2010 Debra L. Picciano . CAP Administrator Federally ...

  2. Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii...

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

    Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii: Assessment and Recommendations Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii: Assessment...

  3. CX-007090: Categorical Exclusion Determination

    Office of Energy Efficiency and Renewable Energy (EERE)

    United States Navy Security System UpgradesCX(s) Applied: B1.15, B2.2Date: 05/24/2011Location(s): Albuquerque, NM; Kings Bay, GA; Bangor, WA, Georgia, New Mexico, WashingtonOffice(s): NNSA-Headquarters, Sandia Site Office

  4. GaAs, AlGaAs and InGaP Tunnel Junctions for Multi-Junction Solar Cells Under Concentration: Resistance Study

    SciTech Connect (OSTI)

    Wheeldon, Jeffrey F.; Valdivia, Christopher E.; Walker, Alex; Kolhatkar, Gitanja; Hall, Trevor J.; Hinzer, Karin; Masson, Denis; Riel, Bruno; Fafard, Simon; Jaouad, Abdelatif; Turala, Artur; Ares, Richard; Aimez, Vincent

    2010-10-14

    The following four TJ designs, AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs are studied to determine minimum doping concentration to achieve a resistance of <10{sup -4} {omega}{center_dot}cm{sup 2} and a peak tunneling current suitable for MJ solar cells up to 1500-suns concentration (operating current of 21 A/cm{sup 2}). Experimentally calibrated numerical models are used to determine how the resistance changes as a function of doping concentration. The AlGaAs/GaAs TJ design is determined to require the least doping concentration to achieve the specified resistance and peak tunneling current, followed by the GaAs/GaAs, and AlGaAs/AlGaAs TJ designs. The AlGaAs/InGaP TJ design can only achieve resistances >5x10{sup -4} {omega}cm{sup 2}.

  5. Neutron calibration sources in the Daya Bay experiment

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

    Liu, J.; Carr, R.; Dwyer, D. A.; Gu, W. Q.; Li, G. S.; McKeown, R. D.; Qian, X.; Tsang, R. H. M.; Wu, F. F.; Zhang, C.

    2015-07-09

    We describe the design and construction of the low rate neutron calibration sources used in the Daya Bay Reactor Anti-neutrino Experiment. Such sources are free of correlated gamma-neutron emission, which is essential in minimizing induced background in the anti-neutrino detector. Thus, the design characteristics have been validated in the Daya Bay anti-neutrino detector.

  6. Low-bay Lighting Energy Conservation Measures

    Energy Science and Technology Software Center (OSTI)

    2010-12-31

    This software requires inputs of simple low-bay lighting system inventory information and calculates the energy and cost benefits of various retrofit opportunities. This tool includes energy conservation measures for: Low-wattage T8 lighting retrofit, T12 to T8 lighting retrofit, LED Exit signs retrofit, Occupancy sensors, Screw-in lighting retrofit, and central lighting controls. This tool calculates energy savings, demand reduction, cooling load reduction, heating load increases, cost savings, building life cycle costs including: Simple payback, discounted payback,more » net-present value, and savings to investment ratio. In addition this tool also displays the environmental benefits of a project.« less

  7. Temperature coefficients for GaInP/GaAs/GaInNAsSb solar cells

    SciTech Connect (OSTI)

    Aho, Arto; Isoaho, Riku; Tukiainen, Antti; Polojärvi, Ville; Aho, Timo; Raappana, Marianna; Guina, Mircea

    2015-09-28

    We report the temperature coefficients for MBE-grown GaInP/GaAs/GaInNAsSb multijunction solar cells and the corresponding single junction sub-cells. Temperature-dependent current-voltage measurements were carried out using a solar simulator equipped with a 1000 W Xenon lamp and a three-band AM1.5D simulator. The triple-junction cell exhibited an efficiency of 31% at AM1.5G illumination and an efficiency of 37–39% at 70x real sun concentration. The external quantum efficiency was also measured at different temperatures. The temperature coefficients up to 80°C, for the open circuit voltage, the short circuit current density, and the conversion efficiency were determined to be −7.5 mV/°C, 0.040 mA/cm{sup 2}/°C, and −0.09%/°C, respectively.

  8. Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)

    SciTech Connect (OSTI)

    Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel; Que, Christopher T.; Yamamoto, Kohji; Tani, Masahiko

    2012-12-15

    Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.

  9. New GaInP/GaAs/GaInAs, Triple-Bandgap, Tandem Solar Cell for High-Efficiency Terrestrial Concentrator Systems

    SciTech Connect (OSTI)

    Kurtz, S.; Wanlass, M.; Kramer, C.; Young, M.; Geisz, J.; Ward, S.; Duda, A.; Moriarty, T.; Carapella, J.; Ahrenkiel, P.; Emery. K.; Jones, K.; Romero, M.; Kibbler, A.; Olson, J.; Friedman, D.; McMahon, W.; Ptak, A.

    2005-11-01

    GaInP/GaAs/GaInAs three-junction cells are grown in an inverted configuration on GaAs, allowing high quality growth of the lattice matched GaInP and GaAs layers before a grade is used for the 1-eV GaInAs layer. Using this approach an efficiency of 37.9% was demonstrated.

  10. Muon Simulation at the Daya Bay SIte

    SciTech Connect (OSTI)

    Mengyun, Guan; Jun, Cao; Changgen, Yang; Yaxuan, Sun; Luk, Kam-Biu

    2006-05-23

    With a pretty good-resolution mountain profile, we simulated the underground muon background at the Daya Bay site. To get the sea-level muon flux parameterization, a modification to the standard Gaisser's formula was introduced according to the world muon data. MUSIC code was used to transport muon through the mountain rock. To deploy the simulation, first we generate a statistic sample of sea-level muon events according to the sea-level muon flux distribution formula; then calculate the slant depth of muon passing through the mountain using an interpolation method based on the digitized data of the mountain; finally transport muons through rock to get underground muon sample, from which we can get results of muon flux, mean energy, energy distribution and angular distribution.

  11. High-bay Lighting Energy Conservation Measures

    Energy Science and Technology Software Center (OSTI)

    2010-12-31

    This software requires inputs of simple high-bay lighting system inventory information and calculates the energy and cost benefits of various retrofit opportunities. This tool includes energy conservation measures for: 1000 Watt to 750 Watt High-pressure Sodium lighting retrofit, 400 Watt to 360 Watt High Pressure Sodium lighting retrofit, High Intensity Discharge to T5 lighting retrofit, High Intensity Discharge to T8 lighting retrofit, and Daylighting. This tool calculates energy savings, demand reduction, cost savings, building lifemore » cycle costs including: simple payback, discounted payback, net-present value, and savings to investment ratio. In addition this tool also displays the environmental benefits of a project.« less

  12. Project Reports for Keweenaw Bay Indian Community- 2010 Project

    Office of Energy Efficiency and Renewable Energy (EERE)

    The Keweenaw Bay Indian Community (KBIC) is committed to preserving our natural environment and reducing the amount of fossil fuels consumed while developing "green" business manufacturing jobs on tribal lands.

  13. Searching for θ13 at Daya Bay

    SciTech Connect (OSTI)

    Giedt, Joel; Napolitano, James

    2015-06-08

    An experiment has been carried out by the Daya Bay Collaboration to measure the neutrino mixing angle θ13. In addition, the grant has supported research into lattice field theory beyond the standard model.

  14. Cross-media approach to saving the Chesapeake Bay

    SciTech Connect (OSTI)

    Appleton, E.L.

    1995-12-01

    A project EPA began in August will investigate the possibility of cross-media emissions trading as a new approach to reducing nitrogen loadings to the Chesapeake Bay. Working with the Environmental Defense Fund (EDF), the Agency hopes to device a NO{sub x} trading framework along the lines of existing sulfur dioxide trading plans to control acid rain. The Chesapeake Air Project will examine the feasibility of using emissions trading between and water sources, including trading credits between power plants and mobile sources, to reduce the atmospheric deposition of nitrogen to the bay. The progress of the Bay Program nutrient reduction goals is up for reevaluation in 1997, and Knopes and EDF economist Brian Morton have high hopes that the trading plan, which would place a cap on the mass of emissions and rate of deposition allowed by all sources, will become the atmospheric deposition portion of the Chesapeake Bay Program`s Nutrient Reduction Strategy. 6 refs.

  15. Huntington Bay, New York: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. Huntington Bay is a village in Suffolk County, New York. It falls under New York's 2nd...

  16. City of Larsen Bay, Alaska (Utility Company) | Open Energy Information

    Open Energy Info (EERE)

    City of Larsen Bay Place: Alaska Phone Number: (907)847-2211 Website: www.swamc.orghtmlsouthwest-a Outage Hotline: (907)847-2211 References: EIA Form EIA-861 Final Data File...

  17. West Bay Shore, New York: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Hide Map This article is a stub. You can help OpenEI by expanding it. West Bay Shore is a census-designated place in Suffolk County, New York.1 References ...

  18. Keweenaw Bay Indian Community- 2010 Energy Efficiency Project

    Broader source: Energy.gov [DOE]

    The goal of the project is to build the staff capacity to enable the Keweenaw Bay Indian Community (KBIC) to establish a tribal weatherization program that promotes energy sufficiency throughout the tribal community.

  19. The ecology of Tampa Bay, Florida: An estuarine profile

    SciTech Connect (OSTI)

    Lewis, R.R. III; Estevez, E.D.

    1988-09-01

    Tampa Bay is Florida's largest open-water estuary and one of the most highly urbanized. This report summarizes and synthesizes many years of scientific investigation into Tampa Bay's geology, hydrology and hydrography, water chemistry, and biotic components. The estuary is a phytoplankton-based system, with mangroves being the second most important primary producer. Benthic organisms are abundant and diverse, although in parts of the bay the benthos consists of a relatively few opportunistic and pollution indicator species. The estuary provides habitat for the juveniles and adults of a number of commercial and recreational fishery species. Significant changes occurring as a result of urbanization and industrialization include significant declines in intertidal wetlands and seagrass meadows, changes in circulation and flushing, and degradation of water quality. Important management issues include dredge and fill operations, restoration of fisheries, increasing freshwater flow to the bay, and eutrophication. 257 refs., 85 figs., 27 tabs.

  20. LISBURNE LISBURNE KUPARUK RIVER PRUDHOE BAY MILNE POINT ALPINE

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

    Gas Reserve Class Prudhoe Bay Area Barrow Area Index Map Northern Alaska Oil and Gas Fields 2004 Onshore Area Gas Reserve Class No 2004 Gas Reserves 0.1 - 10 MMCF 10.1 - 100 MMCF ...

  1. LISBURNE LISBURNE KUPARUK RIVER PRUDHOE BAY MILNE POINT ALPINE

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

    BOE Reserve Class Prudhoe Bay Area Barrow Area Index Map Northern Alaska Oil and Gas Fields 2004 Onshore Area BOE Reserve Class No 2004 Reserves 0.1 - 10 MBOE 10.1 - 100 MBOE 100.1 ...

  2. LISBURNE LISBURNE KUPARUK RIVER PRUDHOE BAY MILNE POINT ALPINE

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

    Liquids Reserve Class Prudhoe Bay Area Barrow Area Index Map Northern Alaska Oil and Gas Fields 2004 Onshore Area Liquids Reserve Class No 2004 Liquids Reserves 0.1 - 10 Mbbl 10.1 ...

  3. Project Reports for Keweenaw Bay Indian Community- 2010 Project

    Broader source: Energy.gov [DOE]

    The goal of the project is to build the staff capacity to enable the Keweenaw Bay Indian Community (KBIC) to establish a tribal weatherization program that promotes energy sufficiency throughout the tribal community.

  4. North Bay Village, Florida: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    it. North Bay Village is a city in Miami-Dade County, Florida. It falls under Florida's 20th congressional district.12 References US Census Bureau Incorporated place and...

  5. The Daya Bay Reactor Neutrino Experiment Sees Evidence that Electron...

    Office of Science (SC) Website

    The two antineutrino detectors in Daya Bay Hall 1, shown here prior to the pool being filled with ultrapure water. The pool is lined with photomultiplier tubes to track any ...

  6. Nassau Bay, Texas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    This article is a stub. You can help OpenEI by expanding it. Nassau Bay is a city in Harris County, Texas. It falls under Texas's 22nd congressional district.12 References...

  7. BayWa Sunways JV | Open Energy Information

    Open Energy Info (EERE)

    JV that specialises in developing, planning and realizing medium-sized to large photovoltaic systems and solar plants. References: BayWa & Sunways JV1 This article is a stub....

  8. Morro Bay, California: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Map This article is a stub. You can help OpenEI by expanding it. Morro Bay is a city in San Luis Obispo County, California. It falls under California's 23rd congressional...

  9. NREL: Wind Research - Building 251 and High Bay

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

    Building 251 and High Bay Photo of an aerial shot of a large blue and grey building with parking lot and cars in the foreground. Building 251 at the NWTC houses administrative and...

  10. Covered Product Category: Industrial Luminaires (High/Low Bay...

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

    2' x 4' 85 1' x 8' 88 High Bay, Non-Linear, Metal Halide Distribution Pattern Input ... ballasts, which should be considered in the comparison of the two system types. ...

  11. InGaAsN/GaAs heterojunction for multi-junction solar cells

    DOE Patents [OSTI]

    Kurtz, Steven R.; Allerman, Andrew A.; Klem, John F.; Jones, Eric D.

    2001-01-01

    An InGaAsN/GaAs semiconductor p-n heterojunction is disclosed for use in forming a 0.95-1.2 eV bandgap photodetector with application for use in high-efficiency multi-junction solar cells. The InGaAsN/GaAs p-n heterojunction is formed by epitaxially growing on a gallium arsenide (GaAs) or germanium (Ge) substrate an n-type indium gallium arsenide nitride (InGaAsN) layer having a semiconductor alloy composition In.sub.x Ga.sub.1-x As.sub.1-y N.sub.y with 0GaAs layer, with the InGaAsN and GaAs layers being lattice-matched to the substrate. The InGaAsN/GaAs p-n heterojunction can be epitaxially grown by either molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD). The InGaAsN/GaAs p-n heterojunction provides a high open-circuit voltage of up to 0.62 volts and an internal quantum efficiency of >70%.

  12. San Francisco Bay Area Aerial Radiation Assessment Survey | National

    National Nuclear Security Administration (NNSA)

    Nuclear Security Administration | (NNSA) San Francisco Bay Area Aerial Radiation Assessment Survey January 27, 2016 (SAN JOSE and SAN FRANCISCO, California) - A helicopter may be seen flying at low altitudes over portions of the San Francisco Bay Area from January 29 through February 6, 2016. The purpose of the flyovers is to measure naturally occurring background radiation. Officials from the National Nuclear Security Administration (NNSA) announced that the radiation assessment will cover

  13. Anderson Bay Shallow Geophysics Report (Other) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Anderson Bay Shallow Geophysics Report Citation Details In-Document Search Title: Anderson Bay Shallow Geophysics Report Conf Paper Authors: Louie, John [1] ; Colton, Dudley ; Marlon, Ramos ; Dustin, Naphan + Show Author Affiliations UNR Publication Date: 2013-09-30 OSTI Identifier: 1111654 Report Number(s): DOE-Pyramid-2842-jl10 DOE Contract Number: EE0002842 Resource Type: Other Research Org: Regents of the Nevada System of Higher Education Sponsoring Org: USDOE Contributing Orgs: PLPT,

  14. Magnetism and transport properties of epitaxial Fe-Ga thin films on GaAs(001)

    SciTech Connect (OSTI)

    Duong Anh Tuan; Shin, Yooleemi; Cho, Sunglae; Dang Duc Dung; Vo Thanh Son

    2012-04-01

    Epitaxial Fe-Ga thin films in disordered bcc {alpha}-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The saturated magnetization (M{sub S}) decreased from 1371 to 1105 kA/m with increasing Ga concentration from 10.5 to 24.3 % at room temperature. The lattice parameter increased with the increase in Ga content because of the larger atomic radius of Ga atom than that of Fe. The increase in carrier density with Ga content caused in lower resistivity.

  15. Graphene induced remote surface scattering in graphene/AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Liu, Xiwen; Li, Dan; Wang, Bobo; Liu, Bin; Chen, Famin; Jin, Guangri; Lu, Yanwu

    2014-10-20

    The mobilities of single-layer graphene combined with AlGaN/GaN heterostructures on two-dimensional electron gases in graphene/AlGaN/GaN double heterojunction are calculated. The impact of electron density in single-layer graphene is also studied. Remote surface roughness (RSR) and remote interfacial charge (RIC) scatterings are introduced into this heterostructure. The mobilities limited by RSR and RIC are an order of magnitude higher than that of interface roughness and misfit dislocation. This study contributes to designing structures for generation of higher electron mobility in graphene/AlGaN/GaN double heterojunction.

  16. Band Structure of Strain-Balanced GaAsBi/GaAsN Super-lattices on GaAs

    SciTech Connect (OSTI)

    Hwang, J.; Phillips, J. D.

    2011-05-31

    GaAs alloys with dilute content of Bi and N provide a large reduction in band-gap energy with increasing alloy composition. GaAsBi/GaAsN heterojunctions have a type-II band alignment, where superlattices based on these materials offer a wide range for designing effective band-gap energy by varying superlattice period and alloy composition. The miniband structure and effective band gap for strain-balanced GaAsBi/GaAsN superlattices with effective lattice match to GaAs are calculated for alloy compositions up to 5% Bi and N using the kp method. The effective band gap for these superlattices is found to vary between 0.89 and 1.32 eV for period thickness ranging from 10 to 100 . The joint density of states and optical absorption of a 40/40 GaAs0.96Bi0.04/GaAs0.98N0.02 superlattice are reported demonstrating a ground-state transition at 1.005 eV and first excited transition at 1.074 eV. The joint density of states is similar in magnitude to GaAs, while the optical absorption is approximately one order of magnitude lower due to the spatially indirect optical transition in the type-II structure. The GaAsBi/GaAsN system may provide a new material system with lattice match to GaAs in a spectral range of high importance for optoelectronic devices including solar cells, photodetectors, and light emitters.

  17. Optical and magnetotransport properties of InGaAs/GaAsSb/GaAs structures doped with a magnetic impurity

    SciTech Connect (OSTI)

    Kalentyeva, I. L. Zvonkov, B. N.; Vikhrova, O. V.; Danilov, Yu. A.; Demina, P. B.; Dorokhin, M. V.; Zdoroveyshchev, A. V.

    2015-11-15

    InGaAs/GaAsSb/GaAs bilayer quantum-well structures containing a magnetic-impurity δ-layer (Mn) at the GaAs/InGaAs interface are experimentally studied for the first time. The structures are fabricated by metal organic chemical-vapor deposition (MOCVD) and laser deposition on substrates of conducting (n{sup +}) and semi-insulating GaAs in a single growth cycle. The InGaAs-layer thickness is varied from 1.5 to 5 nm. The significant effect of a decrease in the InGaAs quantum-well thickness on the optical and magnetotransport properties of the structures under study is detected. Nonlinear magnetic-field dependence of the Hall resistance and negative magnetoresistance at temperatures of ≤30–40 K, circular polarization of the electroluminescence in a magnetic field, opposite behaviors of the photoluminescence and electroluminescence emission intensities in the structures, and an increase in the contribution of indirect transitions with decreasing InGaAs thickness are observed. Simulation shows that these effects can be caused by the influence of the δ-layer of acceptor impurity (Mn) on the band structure and the hole concentration distribution in the bilayer quantum well.

  18. Application to Export Electric Energy OE Docket No. EA-389 Great Bay Energy

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

    VI, LLC | Department of Energy 89 Great Bay Energy VI, LLC Application to Export Electric Energy OE Docket No. EA-389 Great Bay Energy VI, LLC Application from Great Bay Energy to export electric energy to Canada. EA-389 Great Bay Energy VI, (CN).pdf (579.86 KB) More Documents & Publications EA-389 Greay Bay Energy VI, LLC EA-389-A Great Bay Energy VI, LLC Application to Export Electric Energy OE Docket No. EA-327-A DC Energy,

  19. Degradation mechanisms of 2 MeV proton irradiated AlGaN/GaN HEMTs...

    Office of Scientific and Technical Information (OSTI)

    irradiated AlGaNGaN HEMTs This content will become publicly available on August 26, 2016 Title: Degradation mechanisms of 2 MeV proton irradiated AlGaNGaN HEMTs Authors: ...

  20. AlGaAsSb/GaSb Distributed Bragg Reflectors Grown by Organometallic Vapor Phase Epitaxy

    SciTech Connect (OSTI)

    C.A. Wang; C.J. Vineis; D.R. Calawa

    2002-02-13

    The first AlGaAsSb/GaSb quarter-wave distributed Bragg reflectors grown by metallic vapor phase epitaxy are reported. The peak reflectance is 96% for a 10-period structure.

  1. Cathodic Protection of the Yaquina Bay Bridge

    SciTech Connect (OSTI)

    Bullard, Sophie J.; Cramer, Stephen D.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Laylor, H.M.; Cryer, C.B.

    2001-02-01

    The Yaquina Bay Bridge in Newport, Oregon, was designed by Conde B. McCullough and built in 1936. The 3,223-foot (982 m) structure is a combination of concrete arch approach spans and a steel through arch over the shipping channel. Cathodic protection is used to prevent corrosion damage to the concrete arches. The Oregon Department of Transportation (Oregon DOT) installed a carbon anode coating (DAC-85) on two of the north approach spans in 1985. This anode was operated at a current density of 6.6 mA/m2(0.6 mA/ft2). No failure of the conductive anode was observed in 1990, five years after application, or in 2000, 15 years after application. Thermal-sprayed zinc anodes 20 mils (0.5 mm) thick were applied to half the south approach spans beginning in 1990. Thermal-sprayed zinc anodes 15 mils (0.4 mm) thick were applied to the remaining spans in 1996. These anodes were operated at a current density of 2.2 mA/m2(0.2 mA/ft2). In 1999, four zones on the approach spans were included in a two-year field trial of humectants to improve zinc anode performance. The humectants LiNO3 and LiBr were applied to two zones; the two adjacent zones were left untreated as controls. The humectants substantially reduced circuit resistance compared to the controls.

  2. (In,Ga)As/GaP electrical injection quantum dot laser

    SciTech Connect (OSTI)

    Heidemann, M. Höfling, S.; Kamp, M.

    2014-01-06

    The paper reports on the realization of multilayer (In,Ga)As/GaP quantum dot (QD) lasers grown by gas source molecular beam epitaxy. The QDs have been embedded in (Al,Ga)P/GaP waveguide structures. Laser operation at 710 nm is obtained for broad area laser devices with a threshold current density of 4.4 kA/cm{sup 2} at a heat-sink temperature of 80 K.

  3. GaInP/GaAs/GaInAs Monolithic Tandem Cells for High-Performance Solar Concentrators

    SciTech Connect (OSTI)

    Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

    2005-08-01

    We present a new approach for ultra-high-performance tandem solar cells that involves inverted epitaxial growth and ultra-thin device processing. The additional degree of freedom afforded by the inverted design allows the monolithic integration of high-, and medium-bandgap, lattice-matched (LM) subcell materials with lower-bandgap, lattice-mismatched (LMM) materials in a tandem structure through the use of transparent compositionally graded layers. The current work concerns an inverted, series-connected, triple-bandgap, GaInP (LM, 1.87 eV)/GaAs (LM, 1.42 eV)/GaInAs (LMM, {approx}1 eV) device structure grown on a GaAs substrate. Ultra-thin tandem devices are fabricated by mounting the epiwafers to pre-metallized Si wafer handles and selectively removing the parent GaAs substrate. The resulting handle-mounted, ultra-thin tandem cells have a number of important advantages, including improved performance and potential reclamation/reuse of the parent substrate for epitaxial growth. Additionally, realistic performance modeling calculations suggest that terrestrial concentrator efficiencies in the range of 40-45% are possible with this new tandem cell approach. A laboratory-scale (0.24 cm2), prototype GaInP/GaAs/GaInAs tandem cell with a terrestrial concentrator efficiency of 37.9% at a low concentration ratio (10.1 suns) is described, which surpasses the previous world efficiency record of 37.3%.

  4. Replacement of tritiated water from irradiated fuel storage bay

    SciTech Connect (OSTI)

    Castillo, I.; Boniface, H.; Suppiah, S.; Kennedy, B.; Minichilli, A.; Mitchell, T.

    2015-03-15

    Recently, AECL developed a novel method to reduce tritium emissions (to groundwater) and personnel doses at the NRU (National Research Universal) reactor irradiated fuel storage bay (also known as rod or spent fuel bay) through a water swap process. The light water in the fuel bay had built up tritium that had been transferred from the heavy water moderator through normal fuel transfers. The major advantage of the thermal stratification method was that a very effective tritium reduction could be achieved by swapping a minimal volume of bay water and warm tritiated water would be skimmed off the bay surface. A demonstration of the method was done that involved Computational Fluid Dynamics (CFD) modeling of the swap process and a test program that showed excellent agreement with model prediction for the effective removal of almost all the tritium with a minimal water volume. Building on the successful demonstration, AECL fabricated, installed, commissioned and operated a full-scale system to perform a water swap. This full-scale water swap operation achieved a tritium removal efficiency of about 96%.

  5. Metal-interconnection-free integration of InGaN/GaN light emitting diodes with AlGaN/GaN high electron mobility transistors

    SciTech Connect (OSTI)

    Liu, Chao; Cai, Yuefei; Liu, Zhaojun; Ma, Jun; Lau, Kei May

    2015-05-04

    We report a metal-interconnection-free integration scheme for InGaN/GaN light emitting diodes (LEDs) and AlGaN/GaN high electron mobility transistors (HEMTs) by combining selective epi removal (SER) and selective epitaxial growth (SEG) techniques. SER of HEMT epi was carried out first to expose the bottom unintentionally doped GaN buffer and the sidewall GaN channel. A LED structure was regrown in the SER region with the bottom n-type GaN layer (n-electrode of the LED) connected to the HEMTs laterally, enabling monolithic integration of the HEMTs and LEDs (HEMT-LED) without metal-interconnection. In addition to saving substrate real estate, minimal interface resistance between the regrown n-type GaN and the HEMT channel is a significant improvement over metal-interconnection. Furthermore, excellent off-state leakage characteristics of the driving transistor can also be guaranteed in such an integration scheme.

  6. EA-389-A Great Bay Energy VI, LLC | Department of Energy

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

    Rescission of export authorization to export electric energy to Canada. EA-389-A Great Bay ... Energy OE Docket No. EA-389 Great Bay Energy VI, LLC EA-342-A Royal Bank of Canada

  7. Tampa Bay Designated as the Newest Clean Cities Coalition | Department of

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

    Energy Tampa Bay Designated as the Newest Clean Cities Coalition Tampa Bay Designated as the Newest Clean Cities Coalition November 21, 2014 - 1:36pm Addthis Dr. Judy Genshaft, the University of South Florida's president, welcomes attendees to the Tampa Bay Clean Cities Ceremony. | Photo courtesy of the Clean Cities Coalition. Dr. Judy Genshaft, the University of South Florida's president, welcomes attendees to the Tampa Bay Clean Cities Ceremony. | Photo courtesy of the Clean Cities

  8. U.S. Naval Station, Guantanamo Bay, Cuba | Department of Energy

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

    Naval Station, Guantanamo Bay, Cuba U.S. Naval Station, Guantanamo Bay, Cuba Fact sheet describes the Energy Savings Performance Contract (ESPC) success story on environmental stewardship and cost savings at the U.S. Naval Station at Guantanamo Bay, Cuba. Download the U.S. Naval Station at Guantanamo Bay, Cuba fact sheet. (316.37 KB) More Documents & Publications Idaho Operations AMWTP Fact Sheet Heating Ventilation and Air Conditioning Efficiency Greenpower Trap Mufflerl System

  9. Load test of the 272W Building high bay roof deck and support structure

    SciTech Connect (OSTI)

    McCoy, R.M.

    1994-09-28

    This reports the results of the Load Test of the 272W Building High Bay Roof Deck and Support Structure.

  10. A hole modulator for InGaN/GaN light-emitting diodes

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Kyaw, Zabu; Liu, Wei; Ji, Yun; Wang, Liancheng; Tan, Swee Tiam; Sun, Xiao Wei E-mail: VOLKAN@stanfordalumni.org; Demir, Hilmi Volkan E-mail: VOLKAN@stanfordalumni.org

    2015-02-09

    The low p-type doping efficiency of the p-GaN layer has severely limited the performance of InGaN/GaN light-emitting diodes (LEDs) due to the ineffective hole injection into the InGaN/GaN multiple quantum well (MQW) active region. The essence of improving the hole injection efficiency is to increase the hole concentration in the p-GaN layer. Therefore, in this work, we have proposed a hole modulator and studied it both theoretically and experimentally. In the hole modulator, the holes in a remote p-type doped layer are depleted by the built-in electric field and stored in the p-GaN layer. By this means, the overall hole concentration in the p-GaN layer can be enhanced. Furthermore, the hole modulator is adopted in the InGaN/GaN LEDs, which reduces the effective valance band barrier height for the p-type electron blocking layer from ?332?meV to ?294?meV at 80?A/cm{sup 2} and demonstrates an improved optical performance, thanks to the increased hole concentration in the p-GaN layer and thus the improved hole injection into the MQWs.

  11. AlGaN/GaN heterostructure prepared on a Si (110) substrate via pulsed sputtering

    SciTech Connect (OSTI)

    Watanabe, T.; Ohta, J.; Kondo, T.; Ohashi, M.; Ueno, K.; Kobayashi, A.; Fujioka, H.

    2014-05-05

    GaN films were grown on Si (110) substrates using a low-temperature growth technique based on pulsed sputtering. Reduction of the growth temperature suppressed the strain in the GaN films, leading to an increase in the critical thickness for crack formation. In addition, an AlGaN/GaN heterostructure with a flat heterointerface was prepared using this technique. Furthermore, the existence of a two dimensional electron gas at the heterointerface with a mobility of 1360 cm{sup 2}/Vs and a sheet carrier density of 1.3??10{sup 13}?cm{sup ?2} was confirmed. Finally, the use of the AlGaN/GaN heterostructure in a high electron mobility transistor was demonstrated. These results indicate that low-temperature growth via pulsed sputtering is quite promising for the fabrication of GaN-based electronic devices.

  12. Bay State announces growth strategies to cope with changes

    SciTech Connect (OSTI)

    1996-07-01

    A top executive for New England`s biggest independent gas distributor says deregulation of the utility industry offers unprecedented opportunities for growth, but getting there will radically change the way it does business. To achieve dramatic growth, Bay State Gas Co. needs to base their strategies on anticipating the changes in the industry and aggressively positioning themselves to capture the new opportunities that the new business environment is creating. This includes: accelerating the unbundling of transportation service all the way to the residential customer level; forging strategic relationships with retail energy product and service companies as a means of increasing throughput on Bay State`s system; implementing performance-based rates that provide financial incentives for lowering costs and improving customer service; accelerating the implementation of sophisticated information systems to streamline key business processes; and aggressively expanding Bay State`s nonregulated Energy Products and Services business. These steps are discussed.

  13. Project Reports for Bristol Bay Native Corporation- 2003 Project

    Office of Energy Efficiency and Renewable Energy (EERE)

    Bristol Bay Native Corporation (BBNC), through its subsidiary, Bristol Environmental and Engineering Services Corporation, will assess renewable energy opportunities within the BBNC region of southwest Alaska. The goals of this initiative are to encourage tribal self-sufficiency, create jobs, improve environmental quality, and help make our nation more secure through the development of clean, affordable, and reliable renewable energy technologies. The study will identify technologies or systems that could potentially reduce the cost or improve the sustainability of electricity within the Bristol Bay region.

  14. Energy @ Bay Area Maker Faire | Department of Energy

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

    Energy @ Bay Area Maker Faire Energy @ Bay Area Maker Faire It's dubbed the "Greatest Show (and Tell) on Earth." Of course we'll be there! From satellites to a 3D-printed Jeep to remote controlled robots to carbon capture microbeads, we'll be displaying some of the coolest technologies from across the Energy Department. We also want to meet innovators like you! Representatives from the Department of Energy's National Labs, the Office of Energy Efficiency and Renewable Energy (EERE),

  15. EIS-0476: Vogtle Electric Generating Plant in Burke County, GA...

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

    6: Vogtle Electric Generating Plant in Burke County, GA EIS-0476: Vogtle Electric Generating Plant in Burke County, GA EIS-0476: Final Environmental Impact Statement EIS-0476: ...

  16. Carrier quenching in InGaP/GaAs double heterostructures

    SciTech Connect (OSTI)

    Wells, Nathan P. Driskell, Travis U.; Hudson, Andrew I.; LaLumondiere, Stephen D.; Lotshaw, William T.; Forbes, David V.; Hubbard, Seth M.

    2015-08-14

    Photoluminescence measurements on a series of GaAs double heterostructures demonstrate a rapid quenching of carriers in the GaAs layer at irradiance levels below 0.1 W/cm{sup 2} in samples with a GaAs-on-InGaP interface. These results indicate the existence of non-radiative defect centers at or near the GaAs-on-InGaP interface, consistent with previous reports showing the intermixing of In and P when free As impinges on the InGaP surface during growth. At low irradiance, these defect centers can lead to sub-ns carrier lifetimes. The defect centers involved in the rapid carrier quenching can be saturated at higher irradiance levels and allow carrier lifetimes to reach hundreds of nanoseconds. To our knowledge, this is the first report of a nearly three orders of magnitude decrease in carrier lifetime at low irradiance in a simple double heterostructure. Carrier quenching occurs at irradiance levels near the integrated Air Mass Zero (AM0) and Air Mass 1.5 (AM1.5) solar irradiance. Additionally, a lower energy photoluminescence band is observed both at room and cryogenic temperatures. The temperature and time dependence of the lower energy luminescence is consistent with the presence of an unintentional InGaAs or InGaAsP quantum well that forms due to compositional mixing at the GaAs-on-InGaP interface. Our results are of general interest to the photovoltaic community as InGaP is commonly used as a window layer in GaAs based solar cells.

  17. Highly uniform, multi-stacked InGaAs/GaAs quantum dots embedded in a GaAs nanowire

    SciTech Connect (OSTI)

    Tatebayashi, J. Ota, Y.; Ishida, S.; Nishioka, M.; Iwamoto, S.; Arakawa, Y.

    2014-09-08

    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.

  18. Oxidation of ultrathin GaSe

    SciTech Connect (OSTI)

    Thomas Edwin Beechem; McDonald, Anthony E.; Ohta, Taisuke; Howell, Stephen W.; Kalugin, Nikolai G.; Kowalski, Brian M.; Brumbach, Michael T.; Spataru, Catalin D.; Pask, Jesse A.

    2015-10-26

    Oxidation of exfoliated gallium selenide (GaSe) is investigated through Raman, photoluminescence, Auger, and X-ray photoelectron spectroscopies. Photoluminescence and Raman intensity reductions associated with spectral features of GaSe are shown to coincide with the emergence of signatures emanating from the by-products of the oxidation reaction, namely, Ga2Se3 and amorphous Se. Furthermore, photoinduced oxidation is initiated over a portion of a flake highlighting the potential for laser based patterning of two-dimensional heterostructures via selective oxidation.

  19. Oxidation of ultrathin GaSe

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

    Thomas Edwin Beechem; McDonald, Anthony E.; Ohta, Taisuke; Howell, Stephen W.; Kalugin, Nikolai G.; Kowalski, Brian M.; Brumbach, Michael T.; Spataru, Catalin D.; Pask, Jesse A.

    2015-10-26

    Oxidation of exfoliated gallium selenide (GaSe) is investigated through Raman, photoluminescence, Auger, and X-ray photoelectron spectroscopies. Photoluminescence and Raman intensity reductions associated with spectral features of GaSe are shown to coincide with the emergence of signatures emanating from the by-products of the oxidation reaction, namely, Ga2Se3 and amorphous Se. Furthermore, photoinduced oxidation is initiated over a portion of a flake highlighting the potential for laser based patterning of two-dimensional heterostructures via selective oxidation.

  20. OSTIblog Articles in the Thomas Bayes Topic | OSTI, US Dept of Energy

    Office of Scientific and Technical Information (OSTI)

    Office of Scientific and Technical Information Bayes Topic The Reverend Thomas Bayes by Kathy Chambers 06 Nov, 2013 in Products and Content 13432 bayesPicture.jpg The Reverend Thomas Bayes Read more about 13432 During the 1700's, the Reverend Thomas Bayes was a nonconformist minister at the Mount Sion Chapel in Tunbridge Wells, UK, about 40 miles southeast of central London. Having studied both theology and logic at the University of Edinburgh, he was also a mathematician and developed a

  1. EA-1995: Trestle Bay Ecosystem Restoration Project, Clatsop County, Oregon

    Broader source: Energy.gov [DOE]

    The U.S. Army Corps of Engineers prepared, with DOE’s Bonneville Power Administration (BPA) as a cooperating agency, an EA that evaluates the potential environmental impacts of a proposal to improve estuary habitat in Trestle Bay. BPA’s proposed action is to partially fund the proposal.

  2. Covered Product Category: Industrial Luminaires (High/Low Bay)

    Broader source: Energy.gov [DOE]

    The Federal Energy Management Program (FEMP) provides acquisition guidance and Federal efficiency requirements for Industrial Luminaires (High/Low Bay). Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.

  3. Risk assessment for produced water discharges to Louisiana Open Bays

    SciTech Connect (OSTI)

    Meinhold, A.F.; DePhillips, M.P.; Holtzman, S.

    1995-06-23

    Data were collected prior to termination of discharge at three sites (including two open bay sites at Delacroix Island and Bay De Chene) for the risk assessments. The Delacroix Island Oil and Gas Field has been in production since the first well drilling in 1940; the Bay De Chene Field, since 1942. Concentrations of 226Ra, 228Ra, 210Po, and 228Th were measured in discharges. Radium conc. were measured in fish and shellfish tissues. Sediment PAH and metal conc. were also available. Benthos sampling was conducted. A survey of fishermen was conducted. The tiered risk assessment showed that human health risks from radium in produced water appear to be small; ecological risk from radium and other radionuclides in produced water also appear small. Many of the chemical contaminants discharged to open Louisiana bays appear to present little human health or ecological risk. A conservative screening analysis suggested potential risks to human health from Hg and Pb and a potential risk to ecological receptors from total effluent, Sb, Cd, Cu, Pb, Ni, Ag, Zn, and phenol in the water column and PAHs in sediment; quantitiative risk assessments are being done for these contaminants.

  4. JLab Scientist Discusses Higgs Announcement (Tampa Bay Online) | Jefferson

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

    Lab Scientist Discusses Higgs Announcement (Tampa Bay Online) External Link: http://www2.tbo.com/news/opinion/2012/jul/16/naopino1-no-cause-for-envy-in-higgs... By jlab_admin on Mon, 2012-07-16

  5. LISBURNE LISBURNE KUPARUK RIVER PRUDHOE BAY MILNE POINT ALPINE

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

    BOE Reserve Class Prudhoe Bay Area Barrow Area Index Map Northern Alaska Oil and Gas Fields 2004 Onshore Area BOE Reserve Class No 2004 Reserves 0.1 - 10 MBOE 10.1 - 100 MBOE 100.1 - 1,000 MBOE 1,000.1 - 10,000 MBOE 10,000.1 - 100,000 MBOE > 100,000 MBOE

  6. LISBURNE LISBURNE KUPARUK RIVER PRUDHOE BAY MILNE POINT ALPINE

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

    Gas Reserve Class Prudhoe Bay Area Barrow Area Index Map Northern Alaska Oil and Gas Fields 2004 Onshore Area Gas Reserve Class No 2004 Gas Reserves 0.1 - 10 MMCF 10.1 - 100 MMCF 100.1 - 1,000 MMCF 1,000 - 10,000 MMCF 10,000 - 100,000 MMCF > 100,000 MMCF

  7. LISBURNE LISBURNE KUPARUK RIVER PRUDHOE BAY MILNE POINT ALPINE

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

    Liquids Reserve Class Prudhoe Bay Area Barrow Area Index Map Northern Alaska Oil and Gas Fields 2004 Onshore Area Liquids Reserve Class No 2004 Liquids Reserves 0.1 - 10 Mbbl 10.1 - 100 Mbbl 100.1 - 1,000 Mbbl 1,000.1 - 10,000 Mbbl > 10,000 Mbbl

  8. Zinc blende GaAs films grown on wurtzite GaN/sapphire templates

    SciTech Connect (OSTI)

    Chaldyshev, V.V.; Nielsen, B.; Mendez, E.E.; Musikhin, Yu.G.; Bert, N.A.; Ma, Zh.; Holden, Todd

    2005-03-28

    1-{mu}m-thick zinc-blende GaAs (111) films were grown by molecular-beam epitaxy on wurtzite GaN/sapphire (0001) templates. In spite of a {approx}20% lattice mismatch, epitaxial growth was realized, so that the GaAs films showed good adhesion and their surface had a larger mirror-like area with an average surface roughness of 10 nm. Transmission electron microscopy revealed a flat and abrupt epitaxial GaAs/GaN interface with some nanocavities and a large number of dislocations. Reasonably good crystalline quality of the GaAs films was confirmed by Raman characterization. Spectroscopic ellipsometry showed sharp interference fringes and characteristic parameters in the range of 0.75-5.3 eV. Photoluminescence study revealed extended band tails and dominance of non-radiative carrier recombination.

  9. High-performance InGaP/GaAs pnp {delta}-doped heterojunction bipolar transistor

    SciTech Connect (OSTI)

    Tsai, J.-H. Chiu, S.-Y.; Lour, W.-S.; Guo, D.-F.

    2009-07-15

    In this article, a novel InGaP/GaAs pnp {delta}-doped heterojunction bipolar transistor is first demonstrated. Though the valence band discontinuity at InGaP/GaAs heterojunction is relatively large, the addition of a {delta}-doped sheet between two spacer layers at the emitter-base (E-B) junction effectively eliminates the potential spike and increases the confined barrier for electrons, simultaneously. Experimentally, a high current gain of 25 and a relatively low E-B offset voltage of 60 mV are achieved. The offset voltage is much smaller than the conventional InGaP/GaAs pnp HBT. The proposed device could be used for linear amplifiers and low-power complementary integrated circuit applications.

  10. Synthesis, morphology and optical properties of GaN and AlGaN semiconductor nanostructures

    SciTech Connect (OSTI)

    Kuppulingam, B. Singh, Shubra Baskar, K.

    2014-04-24

    Hexagonal Gallium Nitride (GaN) and Aluminum Gallium Nitride (AlGaN) nanoparticles were synthesized by sol-gel method using Ethylene Diamine Tetra Acetic acid (EDTA) complex route. Powder X-ray diffraction (PXRD) analysis confirms the hexagonal wurtzite structure of GaN and Al{sub 0.25}Ga{sub 0.75}N nanoparticles. Surface morphology and elemental analysis were carried out by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX). The room temperature Photoluminescence (PL) study shows the near band edge emission for GaN at 3.35 eV and at 3.59 eV for AlGaN nanoparticles. The Aluminum (Al) composition of 20% has been obtained from PL emission around 345 nm.

  11. Princeton Plasma Physics Lab - General Atomics (GA)

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

    general-atomics-ga General Atomics en The Scorpion's Strategy: "Catch and Subdue" http:www.pppl.govnode1132

  12. Simplified 2DEG carrier concentration model for composite barrier AlGaN/GaN HEMT

    SciTech Connect (OSTI)

    Das, Palash Biswas, Dhrubes

    2014-04-24

    The self consistent solution of Schrodinger and Poisson equations is used along with the total charge depletion model and applied with a novel approach of composite AlGaN barrier based HEMT heterostructure. The solution leaded to a completely new analytical model for Fermi energy level vs. 2DEG carrier concentration. This was eventually used to demonstrate a new analytical model for the temperature dependent 2DEG carrier concentration in AlGaN/GaN HEMT.

  13. GaTe semiconductor for radiation detection

    DOE Patents [OSTI]

    Payne, Stephen A.; Burger, Arnold; Mandal, Krishna C.

    2009-06-23

    GaTe semiconductor is used as a room-temperature radiation detector. GaTe has useful properties for radiation detectors: ideal bandgap, favorable mobilities, low melting point (no evaporation), non-hygroscopic nature, and availability of high-purity starting materials. The detector can be used, e.g., for detection of illicit nuclear weapons and radiological dispersed devices at ports of entry, in cities, and off shore and for determination of medical isotopes present in a patient.

  14. Magnetic coupling in ferromagnetic semiconductor (Ga,Mn)As/(Al,Ga,Mn)As bilayers

    SciTech Connect (OSTI)

    Wang, M.; Wadley, P.; Campion, R. P.; Rushforth, A. W.; Edmonds, K. W.; Gallagher, B. L.; Charlton, T. R.; Kinane, C. J.; Langridge, S.

    2015-08-07

    We report on a study of ferromagnetic semiconductor (Ga,Mn)As/(Al,Ga,Mn)As bilayers using magnetometry and polarized neutron reflectivity (PNR). From depth-resolved characterization of the magnetic structure obtained by PNR, we concluded that the (Ga,Mn)As and (Al,Ga,Mn)As layers have in-plane and perpendicular-to-plane magnetic easy axes, respectively, with weak interlayer coupling. Therefore, the layer magnetizations align perpendicular to each other under low magnetic fields and parallel at high fields.

  15. Accelerated aging of GaAs concentrator solar cells

    SciTech Connect (OSTI)

    Gregory, P.E.

    1982-04-01

    An accelerated aging study of AlGaAs/GaAs solar cells has been completed. The purpose of the study was to identify the possible degradation mechanisms of AlGaAs/GaAs solar cells in terrestrial applications. Thermal storage tests and accelerated AlGaAs corrosion studies were performed to provide an experimental basis for a statistical analysis of the estimated lifetime. Results of this study suggest that a properly designed and fabricated AlGaAs/GaAs solar cell can be mechanically rugged and environmentally stable with projected lifetimes exceeding 100 years.

  16. SODAR DATA FROM OYSTER BAY AT WINYAH BAY NATIONAL ESTUARINE RESEARCH RESERVE

    SciTech Connect (OSTI)

    Nichols, R.; Kohn, J.; Rigas, N.; Boessneck, E.; Kress, E.; Gayes, P.

    2013-04-29

    The SecondWind Triton® is a SODAR (SOnic Detection And Ranging) sonic wind profiler (Triton® sodar) system capable of profiling the wind characteristics up to 200m above the instrument. SODAR systems transmit acoustic chirps into the atmosphere and measure the backscattered signal returned to the device. The primary source of acoustic scattering is variations in air temperature, which cause changes in the refractive index of sound. By measuring the Doppler-shifted frequency of these returned signals, the Triton® can calculate the wind’s speed and direction for the volume of air above the instrument, measured at ten fixed heights, known as station heights. The Triton® is specifically designed for the purpose of wind energy resource assessment as it can remotely capture wind data at heights above ground where wind turbine rotors operate. The measurements made include horizontal wind speed and direction, vertical wind speed, and turbulence. Other integrated sensors provide time and location via GPS, barometric pressure, humidity, and the tilt of the instrument. The study area is located east of Georgetown, South Carolina in North Inlet - Winyah Bay National Estuarine Research Reserve. The monitoring period for data in this report begins 5/14/2009 9:30:00 AM EST and ends 8/2/2010 11:40:00 AM EST.

  17. InGaN/GaN tunnel junctions for hole injection in GaN light emitting diodes

    SciTech Connect (OSTI)

    Krishnamoorthy, Sriram E-mail: rajan@ece.osu.edu; Akyol, Fatih; Rajan, Siddharth E-mail: rajan@ece.osu.edu

    2014-10-06

    InGaN/GaN tunnel junction contacts were grown using plasma assisted molecular beam epitaxy (MBE) on top of a metal-organic chemical vapor deposition (MOCVD)-grown InGaN/GaN blue (450?nm) light emitting diode. A voltage drop of 5.3?V at 100?mA, forward resistance of 2 10{sup ?2} ? cm{sup 2}, and a higher light output power compared to the reference light emitting diodes (LED) with semi-transparent p-contacts were measured in the tunnel junction LED (TJLED). A forward resistance of 5??10{sup ?4} ? cm{sup 2} was measured in a GaN PN junction with the identical tunnel junction contact as the TJLED, grown completely by MBE. The depletion region due to the impurities at the regrowth interface between the MBE tunnel junction and the MOCVD-grown LED was hence found to limit the forward resistance measured in the TJLED.

  18. GaP ring-like nanostructures on GaAs (100) with In{sub 0.15}Ga{sub 0.85}As compensation layers

    SciTech Connect (OSTI)

    Prongjit, Patchareewan Pankaow, Naraporn Boonpeng, Poonyasiri Thainoi, Supachok Panyakeow, Somsak Ratanathammaphan, Somchai

    2013-12-04

    We present the fabrication of GaP ring-like nanostructures on GaAs (100) substrates with inserted In{sub 0.15}Ga{sub 0.85}As compensation layers. The samples are grown by droplet epitaxy using solid-source molecular beam epitaxy. The dependency of nanostructural and optical properties of GaP nanostructures on In{sub 0.15}Ga{sub 0.85}As layer thickness is investigated by ex-situ atomic force microscope (AFM) and photoluminescence (PL). It is found that the characteristics of GaP ring-like structures on GaAs strongly depend on the In{sub 0.15}Ga{sub 0.85}As layer thickness.

  19. Lattice-matched epitaxial GaInAsSb/GaSb thermophotovoltaic devices

    SciTech Connect (OSTI)

    Wang, C.A.; Choi, H.K.; Turner, G.W.; Spears, D.L.; Manfra, M.J.; Charache, G.W.

    1997-05-01

    The materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for lattice-matched thermophotovoltaic (TPV) devices is reported. Epilayers with cutoff wavelength 2--2.4 {micro}m at room temperature and lattice-matched to GaSb substrates were grown by both low-pressure organometallic vapor phase epitaxy and molecular beam epitaxy. These layers exhibit high optical and structural quality. For demonstrating lattice-matched thermophotovoltaic devices, p- and n-type doping studies were performed. Several TPV device structures were investigated, with variations in the base/emitter thicknesses and the incorporation of a high bandgap GaSb or AlGaAsSb window layer. Significant improvement in the external quantum efficiency is observed for devices with an AlGaAsSb window layer compared to those without one.

  20. Green cubic GaInN/GaN light-emitting diode on microstructured silicon (100)

    SciTech Connect (OSTI)

    Stark, Christoph J. M.; Detchprohm, Theeradetch; Wetzel, Christian, E-mail: wetzel@ieee.org [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States) [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Future Chips Constellation, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Lee, S. C.; Brueck, S. R. J. [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States)] [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States); Jiang, Y.-B. [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2013-12-02

    GaInN/GaN light-emitting diodes free of piezoelectric polarization were prepared on standard electronic-grade Si(100) substrates. Micro-stripes of GaN and GaInN/GaN quantum wells in the cubic crystal structure were grown on intersecting (111) planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. Crystal phases were identified in electron back-scattering diffraction. A cross-sectional analysis reveals a cubic structure virtually free of line defects. Electroluminescence over 20 to 100??A is found fixed at 487?nm (peak), 516?nm (dominant). Such structures therefore should allow higher efficiency, wavelength-stable light emitters throughout the visible spectrum.

  1. The detector system of the Daya Bay reactor neutrino experiment

    SciTech Connect (OSTI)

    An, F. P.

    2015-12-15

    The Daya Bay experiment was the first to report simultaneous measurements of reactor antineutrinos at multiple baselines leading to the discovery of ν¯e oscillations over km-baselines. Subsequent data has provided the world's most precise measurement of sin 213 and the effective mass splitting Δm2ee. The experiment is located in Daya Bay, China where the cluster of six nuclear reactors is among the world's most prolific sources of electron antineutrinos. Multiple antineutrino detectors are deployed in three underground water pools at different distances from the reactor cores to search for deviations in the antineutrino rate and energy spectrum due to neutrino mixing. Instrumented with photomultiplier tubes, the water pools serve as shielding against natural radioactivity from the surrounding rock and provide efficient muon tagging. Arrays of resistive plate chambers over the top of each pool provide additional muon detection. The antineutrino detectors were specifically designed for measurements of the antineutrino flux with minimal systematic uncertainty. Relative detector efficiencies between the near and far detectors are known to better than 0.2%. With the unblinding of the final two detectors’ baselines and target masses, a complete description and comparison of the eight antineutrino detectors can now be presented. This study describes the Daya Bay detector systems, consisting of eight antineutrino detectors in three instrumented water pools in three underground halls, and their operation through the first year of eight detector data-taking.

  2. Microbial diversity in restored wetlands of San Francisco Bay

    SciTech Connect (OSTI)

    Theroux, Susanna; Hartman, Wyatt; He, Shaomei; Tringe, Susannah

    2013-12-09

    Wetland ecosystems may serve as either a source or a sink for atmospheric carbon and greenhouse gases. This delicate carbon balance is influenced by the activity of belowground microbial communities that return carbon dioxide and methane to the atmosphere. Wetland restoration efforts in the San Francisco Bay-Delta region may help to reverse land subsidence and possibly increase carbon storage in soils. However, the effects of wetland restoration on microbial communities, which mediate soil metabolic activity and carbon cycling, are poorly studied. In an effort to better understand the underlying factors which shape the balance of carbon flux in wetland soils, we targeted the microbial communities in a suite of restored and historic wetlands in the San Francisco Bay-Delta region. Using DNA and RNA sequencing, coupled with greenhouse gas monitoring, we profiled the diversity and metabolic potential of the wetland soil microbial communities along biogeochemical and wetland age gradients. Our results show relationships among geochemical gradients, availability of electron acceptors, and microbial community composition. Our study provides the first genomic glimpse into microbial populations in natural and restored wetlands of the San Francisco Bay-Delta region and provides a valuable benchmark for future studies.

  3. The detector system of the Daya Bay reactor neutrino experiment

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

    An, F. P.

    2015-12-15

    The Daya Bay experiment was the first to report simultaneous measurements of reactor antineutrinos at multiple baselines leading to the discovery of ν¯e oscillations over km-baselines. Subsequent data has provided the world's most precise measurement of sin 22θ13 and the effective mass splitting Δm2ee. The experiment is located in Daya Bay, China where the cluster of six nuclear reactors is among the world's most prolific sources of electron antineutrinos. Multiple antineutrino detectors are deployed in three underground water pools at different distances from the reactor cores to search for deviations in the antineutrino rate and energy spectrum due to neutrinomore » mixing. Instrumented with photomultiplier tubes, the water pools serve as shielding against natural radioactivity from the surrounding rock and provide efficient muon tagging. Arrays of resistive plate chambers over the top of each pool provide additional muon detection. The antineutrino detectors were specifically designed for measurements of the antineutrino flux with minimal systematic uncertainty. Relative detector efficiencies between the near and far detectors are known to better than 0.2%. With the unblinding of the final two detectors’ baselines and target masses, a complete description and comparison of the eight antineutrino detectors can now be presented. This study describes the Daya Bay detector systems, consisting of eight antineutrino detectors in three instrumented water pools in three underground halls, and their operation through the first year of eight detector data-taking.« less

  4. Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii:

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

    Assessment and Recommendations | Department of Energy Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii: Assessment and Recommendations Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii: Assessment and Recommendations NREL performed a comprehensive assessment to appraise the potential of MCBH Kaneohe Bay to achieve net zero energy status through energy efficiency, renewable energy, and electric vehicle integration. This report summarizes the results of the

  5. Computing Sciences Staff Help East Bay High Schoolers Upgrade their Summer

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

    Computing Sciences Staff Help East Bay High Schoolers Upgrade their Summer Computing Sciences Staff Help East Bay High Schoolers Upgrade their Summer August 6, 2015 Jon Bashor, jbashor@lbl.gov, +1 510 486 5849 To help prepare students from underrepresented groups learn about careers in a variety of IT fields, the Laney College Computer Information Systems Department offered its Upgrade: Computer Science Program. Thirty-eight students from 10 East Bay high schools registered for the eight-week

  6. Inter-Tribal Council of Michigan, Inc. - Bay Mills Indian Community Energy Reduction Feasibility Study

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

    --Tribal Council of Michigan, Inc. Environmental Services Division Bay Mills Indian Community Energy Reduc<on Feasibility Study Chris K ushman Thank You *DOE Tribal Energy Program *Tribal Energy Program Review presenters *Bay Mills Indian Community Bay Mills Indian Community * Upper Peninsula of Michigan - Cold temperatures - Prolonged exposure to strong north winds off Lake Superior - Short winter daylight * Fishing and fish consuming community * Electricity largely supplied by coal fired

  7. GaAs photoconductive semiconductor switch

    DOE Patents [OSTI]

    Loubriel, G.M.; Baca, A.G.; Zutavern, F.J.

    1998-09-08

    A high gain, optically triggered, photoconductive semiconductor switch (PCSS) implemented in GaAs as a reverse-biased pin structure with a passivation layer above the intrinsic GaAs substrate in the gap between the two electrodes of the device is disclosed. The reverse-biased configuration in combination with the addition of the passivation layer greatly reduces surface current leakage that has been a problem for prior PCSS devices and enables employment of the much less expensive and more reliable DC charging systems instead of the pulsed charging systems that needed to be used with prior PCSS devices. 5 figs.

  8. GaAs photoconductive semiconductor switch

    DOE Patents [OSTI]

    Loubriel, Guillermo M.; Baca, Albert G.; Zutavern, Fred J.

    1998-01-01

    A high gain, optically triggered, photoconductive semiconductor switch (PCSS) implemented in GaAs as a reverse-biased pin structure with a passivation layer above the intrinsic GaAs substrate in the gap between the two electrodes of the device. The reverse-biased configuration in combination with the addition of the passivation layer greatly reduces surface current leakage that has been a problem for prior PCSS devices and enables employment of the much less expensive and more reliable DC charging systems instead of the pulsed charging systems that needed to be used with prior PCSS devices.

  9. GaN: Defect and Device Issues

    SciTech Connect (OSTI)

    Pearton, S.J.; Ren, F.; Shul, R.J.; Zolper, J.C.

    1998-11-09

    The role of extended and point defects, and key impurities such as C, O and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

  10. Make Energy at the Bay Area Maker Faire | Department of Energy

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

    Make Energy at the Bay Area Maker Faire Make Energy at the Bay Area Maker Faire June 20, 2016 - 12:10pm Addthis Make Energy at the Bay Area Maker Faire Video from the Department of Energy, published June 17, 2016. This past May, nine Department of Energy (DOE) national labs and three DOE program offices hosted the first Make|ENERGY Pavilion at the Bay Area Maker Faire in San Mateo, California. It featured a number of smart and exciting hands-on displays for kids and adults to explore, and

  11. MHK Projects/San Francisco Bay Tidal Energy Project | Open Energy...

    Open Energy Info (EERE)

    Francisco Bay Tidal Energy Project < MHK Projects Jump to: navigation, search << Return to the MHK database homepage Loading map... "minzoom":false,"mappingservice":"googlemaps3",...

  12. Bay Area national labs team to tackle long-standing automotive...

    National Nuclear Security Administration (NNSA)

    Bay Area national labs team to tackle long-standing automotive hydrogen storage challenge ... Light Source facility, is leading the Hydrogen Materials - Advanced Research Consortium ...

  13. Design of a basinwide monitoring program for the Tampa Bay estuary. Final technical pub

    SciTech Connect (OSTI)

    Hochberg, R.J.; Weisberg, S.B.; Frithsen, J.B.

    1992-10-30

    The Tampa Bay National Estuary Program (TBNEP) is developing a Comprehensive Conservation and Management Plan (CCMP) to recommend management actions for protecting the Tampa Bay estuary. The purpose of the document is to facilitate development of the monitoring program by assisting the TBNEP to define the objectives of a monitoring program for Tampa Bay identifying indicators and a sampling design that are appropriate to those objectives, and identifying how existing Tampa Bay monitoring programs can be incorporated and modified (if necessary) to meet the monitoring objectives.

  14. Building America Whole-House Solutions for Existing HomesBay...

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

    HomesBay Ridge Gardens - Mixed Humid Affordable Multifamily Housing Deep Energy Retrofit, ... Ridge Gardens - Mixed Humid Affordable Multifamily Housing Deep Energy Retrofit, ...

  15. Enhanced thermoelectric transport in modulation-doped GaN/AlGaN core/shell nanowires

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

    Song, Erdong; Li, Qiming; Swartzentruber, Brian; Pan, Wei; Wang, George T.; Martinez, Julio A.

    2015-11-25

    The thermoelectric properties of unintentionally n-doped core GaN/AlGaN core/shell N-face nanowires are reported. We found that the temperature dependence of the electrical conductivity is consistent with thermally activated carriers with two distinctive donor energies. The Seebeck coefficient of GaN/AlGaN nanowires is more than twice as large as that for the GaN nanowires alone. However, an outer layer of GaN deposited onto the GaN/AlGaN core/shell nanowires decreases the Seebeck coefficient at room temperature, while the temperature dependence of the electrical conductivity remains the same. We attribute these observations to the formation of an electron gas channel within the heavily-doped GaN coremore » of the GaN/AlGaN nanowires. The room-temperature thermoelectric power factor for the GaN/AlGaN nanowires can be four times higher than the GaN nanowires. As a result, selective doping in bandgap engineered core/shell nanowires is proposed for enhancing the thermoelectric power.« less

  16. Enhanced thermoelectric transport in modulation-doped GaN/AlGaN core/shell nanowires

    SciTech Connect (OSTI)

    Song, Erdong; Li, Qiming; Swartzentruber, Brian; Pan, Wei; Wang, George T.; Martinez, Julio A.

    2015-11-25

    The thermoelectric properties of unintentionally n-doped core GaN/AlGaN core/shell N-face nanowires are reported. We found that the temperature dependence of the electrical conductivity is consistent with thermally activated carriers with two distinctive donor energies. The Seebeck coefficient of GaN/AlGaN nanowires is more than twice as large as that for the GaN nanowires alone. However, an outer layer of GaN deposited onto the GaN/AlGaN core/shell nanowires decreases the Seebeck coefficient at room temperature, while the temperature dependence of the electrical conductivity remains the same. We attribute these observations to the formation of an electron gas channel within the heavily-doped GaN core of the GaN/AlGaN nanowires. The room-temperature thermoelectric power factor for the GaN/AlGaN nanowires can be four times higher than the GaN nanowires. As a result, selective doping in bandgap engineered core/shell nanowires is proposed for enhancing the thermoelectric power.

  17. Optical spectroscopy of quantum confined states in GaAs/AlGaAs quantum well tubes

    SciTech Connect (OSTI)

    Shi, Teng; Fickenscher, Melodie; Smith, Leigh; Jackson, Howard; Yarrison-Rice, Jan; Gao, Qiang; Tan, Hoe; Jagadish, Chennupati; Etheridge, Joanne; Wong, Bryan M.

    2013-12-04

    We have investigated the quantum confinement of electronic states in GaAs/Al{sub x}Ga{sub 1?x}As nanowire heterostructures which contain radial GaAs quantum wells of either 4nm or 8nm. Photoluminescence and photoluminescence excitation spectroscopy are performed on single nanowires. We observed emission and excitation of electron and hole confined states. Numerical calculations of the quantum confined states using the detailed structural information on the quantum well tubes show excellent agreement with these optical results.

  18. InGaAs/GaAs quantum dot interdiffiusion induced by cap layer overgrowth

    SciTech Connect (OSTI)

    Jasinski, J.; Babinski, A.; Czeczott, M.; Bozek, R.

    2000-06-28

    The effect of thermal treatment during and after growth of InGaAs/GaAs quantum dot (QD) structures was studied. Transmission electron microscopy and atomic force microscopy confirmed the presence of interacting QDs, as was expected from analysis of temperature dependence of QD photoluminescence (PL) peak. The results indicate that the effect of post-growth annealing can be similar to the effect of elevated temperature of capping layer growth. Both, these thermal treatments can lead to a similar In and Ga interdiffiusion resulting in a similar blue-shift of QD PL peak.

  19. Structural and optical properties of InGaN--GaN nanowire heterostructures grown by molecular beam epitaxy

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

    Limbach, F.; Gotschke, T.; Stoica, T.; Calarco, R.; Sutter, E.; Ciston, J.; Cusco, R.; Artus, L.; Kremling, S.; Hofling, S.; et al

    2011-01-01

    InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaNmore » to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, μ-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.« less

  20. Structural and optical properties of InGaN--GaN nanowire heterostructures grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Limbach, F.; Gotschke, T.; Stoica, T.; Calarco, R.; Sutter, E.; Ciston, J.; Cusco, R.; Artus, L.; Kremling, S.; Hofling, S.; Worschech, L.; Grutzmacher, D.

    2011-01-01

    InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaN to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, μ-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.

  1. Structural and optical properties of InGaNGaN nanowire heterostructures grown by molecular beam epitaxy

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

    Limbach, F.; Gotschke, T.; Stoica, T.; Calarco, R.; Sutter, E.; Ciston, J.; Cusco, R.; Artus, L.; Kremling, S.; Ho?fling, S.; et al

    2011-01-01

    InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaNmoreto higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, ?-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.less

  2. Investigation of surface-plasmon coupled red light emitting InGaN/GaN multi-quantum well with Ag nanostructures coated on GaN surface

    SciTech Connect (OSTI)

    Li, Yi; Liu, Bin E-mail: rzhang@nju.edu.cn; Zhang, Rong E-mail: rzhang@nju.edu.cn; Xie, Zili; Zhuang, Zhe; Dai, JiangPing; Tao, Tao; Zhi, Ting; Zhang, Guogang; Chen, Peng; Ren, Fangfang; Zhao, Hong; Zheng, Youdou

    2015-04-21

    Surface-plasmon (SP) coupled red light emitting InGaN/GaN multiple quantum well (MQW) structure is fabricated and investigated. The centre wavelength of 5-period InGaN/GaN MQW structure is about 620?nm. The intensity of photoluminescence (PL) for InGaN QW with naked Ag nano-structures (NS) is only slightly increased due to the oxidation of Ag NS as compared to that for the InGaN QW. However, InGaN QW with Ag NS/SiO{sub 2} structure can evidently enhance the emission efficiency due to the elimination of surface oxide layer of Ag NS. With increasing the laser excitation power, the PL intensity is enhanced by 25%53% as compared to that for the SiO{sub 2} coating InGaN QW. The steady-state electric field distribution obtained by the three-dimensional finite-difference time-domain method is different for both structures. The proportion of the field distributed in the Ag NS for the GaN/Ag NS/SiO{sub 2} structure is smaller as compared to that for the GaN/naked Ag NS structure. As a result, the energy loss of localized SP modes for the GaN/naked Ag NS structure will be larger due to the absorption of Ag layer.

  3. Strain-compensated (Ga,In)N/(Al,Ga)N/GaN multiple quantum wells for improved yellow/amber light emission

    SciTech Connect (OSTI)

    Lekhal, K.; Damilano, B. De Mierry, P.; Venngus, P.; Ngo, H. T.; Rosales, D.; Gil, B.; Hussain, S.

    2015-04-06

    Yellow/amber (570600?nm) emitting In{sub x}Ga{sub 1?x}N/Al{sub y}Ga{sub 1?y}N/GaN multiple quantum wells (QWs) have been grown by metal organic chemical vapor deposition on GaN-on- sapphire templates. When the (Al,Ga)N thickness of the barrier increases, the room temperature photoluminescence is red-shifted while its yield increases. This is attributed to an increase of the QW internal electric field and an improvement of the material quality due to the compensation of the compressive strain of the In{sub x}Ga{sub 1?x}N QWs by the Al{sub y}Ga{sub 1?y}N layers, respectively.

  4. Chedabucto Bay 1992 shoreline oil conditions survey: Long-term fate of bunker C oil from the arrow spill in Chedabucto Bay, Nova Scotia

    SciTech Connect (OSTI)

    Owens, E.H.; McGuire, B.E.; Humphrey, B.

    1994-03-01

    The report presents a description of the activities related to and a summary of the information generated by a field survey carried out in Chedabucto Bay, Nova Scotia, for Environment Canada from June to September 1992. The objective of the survey was to locate and document any residual oil on the shores of Chedabucto Bay. The grounding of the tanker Arrow in February 1970 resulted in the release of more than 11 million liters of Bunker C fuel oil. This oil was stranded over an estimated 305 km of shoreline in the Chedabucto Bay area.

  5. Composition profiling of GaAs/AlGaAs quantum dots grown by droplet epitaxy

    SciTech Connect (OSTI)

    Bocquel, J.; Koenraad, P. M.; Giddings, A. D.; Prosa, T. J.; Larson, D. J.; Mano, T.

    2014-10-13

    Droplet epitaxy (DE) is a growth method which can create III-V quantum dots (QDs) whose optoelectronic properties can be accurately controlled through the crystallisation conditions. In this work, GaAs/AlGaAs DE-QDs have been analyzed with the complimentary techniques of cross-sectional scanning tunneling microscopy and atom probe tomography. Structural details and a quantitative chemical analysis of QDs of different sizes are obtained. Most QDs were found to be pure GaAs, while a small proportion exhibited high intermixing caused by a local etching process. Large QDs with a high aspect ratio were observed to have an Al-rich crown above the GaAs QD. This structure is attributed to differences in mobility of the cations during the capping phase of the DE growth.

  6. High-field quasi-ballistic transport in AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Danilchenko, B. A.; Tripachko, N. A.; Belyaev, A. E.; Vitusevich, S. A. Hardtdegen, H.; Lth, H.

    2014-02-17

    Mechanisms of electron transport formation in 2D conducting channels of AlGaN/GaN heterostructures in extremely high electric fields at 4.2?K have been studied. Devices with a narrow constriction for the current flow demonstrate high-speed electron transport with an electron velocity of 6.8??10{sup 7}?cm/s. Such a velocity is more than two times higher than values reported for conventional semiconductors and about 15% smaller than the limit value predicted for GaN. Superior velocity is attained in the channel with considerable carrier reduction. The effect is related to a carrier runaway phenomenon. The results are in good agreement with theoretical predictions for GaN-based materials.

  7. On strongly GA-convex functions and stochastic processes

    SciTech Connect (OSTI)

    Bekar, Nurgl Okur; Akdemir, Hande Gnay; ??can, ?mdat

    2014-08-20

    In this study, we introduce strongly GA-convex functions and stochastic processes. We provide related well-known Kuhn type results and Hermite-Hadamard type inequality for strongly GA-convex functions and stochastic processes.

  8. Sheet resistance under Ohmic contacts to AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Hajłasz, M.; Donkers, J. J. T. M.; Sque, S. J.; Heil, S. B. S.; Gravesteijn, D. J.; Rietveld, F. J. R.; Schmitz, J.

    2014-06-16

    For the determination of specific contact resistance in semiconductor devices, it is usually assumed that the sheet resistance under the contact is identical to that between the contacts. This generally does not hold for contacts to AlGaN/GaN structures, where an effective doping under the contact is thought to come from reactions between the contact metals and the AlGaN/GaN. As a consequence, conventional extraction of the specific contact resistance and transfer length leads to erroneous results. In this Letter, the sheet resistance under gold-free Ti/Al-based Ohmic contacts to AlGaN/GaN heterostructures on Si substrates has been investigated by means of electrical measurements, transmission electron microscopy, and technology computer-aided design simulations. It was found to be significantly lower than that outside of the contact area; temperature-dependent electrical characterization showed that it exhibits semiconductor-like behavior. The increase in conduction is attributed to n-type activity of nitrogen vacancies in the AlGaN. They are thought to form during rapid thermal annealing of the metal stack when Ti extracts nitrogen from the underlying semiconductor. The high n-type doping in the region between the metal and the 2-dimensional electron gas pulls the conduction band towards the Fermi level and enhances horizontal electron transport in the AlGaN. Using this improved understanding of the properties of the material underneath the contact, accurate values of transfer length and specific contact resistance have been extracted.

  9. On-sun concentrator performance of GaInP/GaAs tandem cells

    SciTech Connect (OSTI)

    Friedman, D.J.; Kurtz, S.R.; Sinha, K.; McMahon, W.E.; Olson, J.M.

    1996-05-01

    The GaInP/GaAs concentrator device has been adapted for and tested in a prototype {open_quotes}real-world{close_quotes} concentrator power system. The device achieved an on-sun efficiency of 28% {+-} 1% in the range of approximately 200-260 suns with device operating temperatures of 38{degrees}C to 42{degrees}C. The authors discuss ways of further improving this performance for future devices.

  10. InGaAs/GaAs (110) quantum dot formation via step meandering

    SciTech Connect (OSTI)

    Diez-Merino, Laura; Tejedor, Paloma

    2011-07-01

    InGaAs (110) semiconductor quantum dots (QDs) offer very promising prospects as a material base for a new generation of high-speed spintronic devices, such as single electron transistors for quantum computing. However, the spontaneous formation of InGaAs QDs is prevented by two-dimensional (2D) layer-by-layer growth on singular GaAs (110) substrates. In this work we have studied, by using atomic force microscopy and photoluminescence spectroscopy (PL), the growth of InGaAs/GaAs QDs on GaAs (110) stepped substrates by molecular beam epitaxy (MBE), and the modification of the adatom incorporation kinetics to surface steps in the presence of chemisorbed atomic hydrogen. The as-grown QDs exhibit lateral dimensions below 100 nm and emission peaks in the 1.35-1.37 eV range. It has been found that a step meandering instability derived from the preferential attachment of In adatoms to [110]-step edges relative to [11n]-type steps plays a key role in the destabilization of 2D growth that leads to 3D mound formation on both conventional and H-terminated vicinal substrates. In the latter case, the driving force for 3D growth via step meandering is enhanced by H-induced upward mass transport in addition to the lower energy cost associated with island formation on H-terminated substrates, which results in a high density array of InGaAs/GaAs dots selectively nucleated on the terrace apices with reduced lateral dimensions and improved PL efficiency relative to those of conventional MBE-grown samples.

  11. AlGaAs/GaAs photovoltaic converters for high power narrowband radiation

    SciTech Connect (OSTI)

    Khvostikov, Vladimir; Kalyuzhnyy, Nikolay; Mintairov, Sergey; Potapovich, Nataliia; Shvarts, Maxim; Sorokina, Svetlana; Andreev, Viacheslav; Luque, Antonio

    2014-09-26

    AlGaAs/GaAs-based laser power PV converters intended for operation with high-power (up to 100 W/cm{sup 2}) radiation were fabricated by LPE and MOCVD techniques. Monochromatic (? = 809 nm) conversion efficiency up to 60% was measured at cells with back surface field and low (x = 0.2) Al concentration 'window'. Modules with a voltage of 4 V and the efficiency of 56% were designed and fabricated.

  12. Lateral and Vertical Transistors Using the AlGaN/GaN Heterostructure

    SciTech Connect (OSTI)

    Chowdhury, S; Mishra, UK

    2013-10-01

    Power conversion losses are endemic in all areas of electricity consumption, including motion control, lighting, air conditioning, and information technology. Si, the workhorse of the industry, has reached its material limits. Increasingly, the lateral AlGaN/GaN HEMT based on gallium nitride (GaN-on-Si) is becoming the device of choice for medium power electronics as it enables high-power conversion efficiency and reduced form factor at attractive pricing for wide market penetration. The reduced form factor enabled by high-efficiency operation at high frequency further enables significant system price reduction because of savings in bulky extensive passive elements and heat sink costs. The high-power market, however, still remains unaddressed by lateral GaN devices. The current and voltage demand for high power conversion application makes the chip area in a lateral topology so large that it becomes more difficult to manufacture. Vertical GaN devices would play a big role alongside of silicon carbide (SiC) to address the high power conversion needs. In this paper, the development, performance, and status of lateral and vertical GaN devices are discussed.

  13. GaNPAs Solar Cells Lattice-Matched To GaP: Preprint

    SciTech Connect (OSTI)

    Geisz, J. F.; Friedman, D. J.; Kurtz, S.

    2002-05-01

    This conference paper describes the III-V semiconductors grown on silicon substrates are very attractive for lower-cost, high-efficiency multijunction solar cells, but lattice-mismatched alloys that result in high dislocation densities have been unable to achieve satisfactory performance. GaNxP1-x-yAsy is a direct-gap III-V alloy that can be grown lattice-matched to Si when y= 4.7x - 0.1. We propose the use of lattice-matched GaNPAs on silicon for high-efficiency multijunction solar cells. We have grown GaNxP1-x-yAsy on GaP (with a similar lattice constant to silicon) by metal-organic chemical vapor phase epitaxy with direct band-gaps in the range of 1.5 to 2.0 eV. We demonstrate the performance of single-junction GaNxP1-x-yAsy solar cells grown on GaP substrates and discuss the prospects for the development of monolithic high-efficiency multijunction solar cells based on silicon substrates.

  14. Key Neutrino behavior observed at Daya Bay (The College of William and

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

    Mary) | Jefferson Lab Key Neutrino behavior observed at Daya Bay (The College of William and Mary) External Link: http://www.wm.edu/news/stories/2012/key-neutrino-behavior-observed-at-daya-bay-1... By jlab_admin on Thu, 2012-03-08

  15. The Muon System of the Daya Bay Reactor Antineutrino Experiment

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

    An, F. P.; Hackenburg, R. W.; Brown, R. E.; Chasman, C.; Dale, E.; Diwan, M. V.; Gill, R.; Hans, S.; Isvan, Z.; Jaffe, D. E.; et al

    2014-10-05

    The Daya Bay experiment consists of functionally identical antineutrino detectors immersed in pools of ultrapure water in three well-separated underground experimental halls near two nuclear reactor complexes. These pools serve both as shields against natural, low-energy radiation, and as water Cherenkov detectors that efficiently detect cosmic muons using arrays of photomultiplier tubes. Each pool is covered by a plane of resistive plate chambers as an additional means of detecting muons. Design, construction, operation, and performance of these muon detectors are described. (auth)

  16. ESnet, Orange Silicon Valley, and Bay Microsystems Demonstrate the

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

    World's First Long Distance 40Gbps RDMA Data Transfer ESnet, Orange Silicon Valley, and Bay Microsystems Demonstrate the World's First Long Distance 40Gbps RDMA Data Transfer News & Publications ESnet News Media & Press Publications and Presentations Galleries ESnet Awards and Honors Contact Us Media Jon Bashor, jbashor@lbl.gov, +1 510 486 5849 or Media@es.net Technical Assistance: 1 800-33-ESnet (Inside the US) 1 800-333-7638 (Inside the US) 1 510-486-7600 (Globally) 1 510-486-7607

  17. Lattice-Mismatched GaAs/InGaAs Two-Junction Solar Cells by Direct Wafer Bonding

    SciTech Connect (OSTI)

    Tanabe, K.; Aiken, D. J.; Wanlass, M. W.; Morral, A. F.; Atwater, H. A.

    2006-01-01

    Direct bonded interconnect between subcells of a lattice-mismatched III-V compound multijunction cell would enable dislocation-free active regions by confining the defect network needed for lattice mismatch accommodation to tunnel junction interfaces, while metamorphic growth inevitably results in less design flexibility and lower material quality than is desirable. The first direct-bond interconnected multijunction solar cell, a two-terminal monolithic GaAs/InGaAs two-junction solar cell, is reported and demonstrates viability of direct wafer bonding for solar cell applications. The tandem cell open-circuit voltage was approximately the sum of the subcell open-circuit voltages. This achievement shows direct bonding enables us to construct lattice-mismatched III-V multijunction solar cells and is extensible to an ultrahigh efficiency InGaP/GaAs/InGaAsP/InGaAs four-junction cell by bonding a GaAs-based lattice-matched InGaP/GaAs subcell and an InP-based lattice-matched InGaAsP/InGaAs subcell. The interfacial resistance experimentally obtained for bonded GaAs/InP smaller than 0.10 Ohm-cm{sup 2} would result in a negligible decrease in overall cell efficiency of {approx}0.02%, under 1-sun illumination.

  18. Hybrid type-I InAs/GaAs and type-II GaSb/GaAs quantum dot structure with enhanced photoluminescence

    SciTech Connect (OSTI)

    Ji, Hai-Ming; Liang, Baolai Simmonds, Paul J.; Juang, Bor-Chau; Yang, Tao; Young, Robert J.; Huffaker, Diana L.

    2015-03-09

    We investigate the photoluminescence (PL) properties of a hybrid type-I InAs/GaAs and type-II GaSb/GaAs quantum dot (QD) structure grown in a GaAs matrix by molecular beam epitaxy. This hybrid QD structure exhibits more intense PL with a broader spectral range, compared with control samples that contain only InAs or GaSb QDs. This enhanced PL performance is attributed to additional electron and hole injection from the type-I InAs QDs into the adjacent type-II GaSb QDs. We confirm this mechanism using time-resolved and power-dependent PL. These hybrid QD structures show potential for high efficiency QD solar cell applications.

  19. Properties of (Ga,Mn)As codoped with Li

    SciTech Connect (OSTI)

    Miyakozawa, Shohei; Chen, Lin; Matsukura, Fumihiro; Ohno, Hideo

    2014-06-02

    We grow Li codoped (Ga,Mn)As layers with nominal Mn composition up to 0.15 by molecular beam epitaxy. The layers before and after annealing are characterized by x-ray diffraction, transport, magnetization, and ferromagnetic resonance measurements. The codoping with Li reduces the lattice constant and electrical resistivity of (Ga,Mn)As after annealing. We find that (Ga,Mn)As:Li takes similar Curie temperature to that of (Ga,Mn)As, but with pronounced magnetic moments and in-plane magnetic anisotropy, indicating that the Li codoping has nontrivial effects on the magnetic properties of (Ga,Mn)As.

  20. Study of the effects of GaN buffer layer quality on the dc characteristics of AlGaN/GaN high electron mobility transistors

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

    Ahn, Shihyun; Zhu, Weidi; Dong, Chen; Le, Lingcong; Hwang, Ya-Hsi; Kim, Byung-Jae; Ren, Fan; Pearton, Stephen J.; Lind, Aaron G.; Jones, Kevin S.; et al

    2015-04-21

    Here we studied the effect of buffer layer quality on dc characteristics of AlGaN/GaN high electron mobility (HEMTs). AlGaN/GaN HEMT structures with 2 and 5 μm GaN buffer layers on sapphire substrates from two different vendors with the same Al concentration of AlGaN were used. The defect densities of HEMT structures with 2 and 5 μm GaN buffer layer were 7 × 109 and 5 × 108 cm₋2, respectively, as measured by transmission electron microscopy. There was little difference in drain saturation current or in transfer characteristics in HEMTs on these two types of buffer. However, there was no dispersionmore » observed on the nonpassivated HEMTs with 5 μm GaN buffer layer for gate-lag pulsed measurement at 100 kHz, which was in sharp contrast to the 71% drain current reduction for the HEMT with 2 μm GaN buffer layer.« less

  1. Reactive codoping of GaAlInP compound semiconductors

    DOE Patents [OSTI]

    Hanna, Mark Cooper; Reedy, Robert

    2008-02-12

    A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

  2. Three-junction solar cells comprised of a thin-film GaInP/GaAs tandem cell mechanically stacked on a Si cell

    SciTech Connect (OSTI)

    Yazawa, Y.; Tamura, K.; Watahiki, S.; Kitatani, T.; Ohtsuka, H.; Warabisako, T.

    1997-12-31

    Three-junction tandem solar cells were fabricated by mechanical stacking of a thin-film GaInP/GaAs monolithic tandem cell and a Si cell. The epitaxial lift-off (ELO) technique was used for the thinning of GaInP/GaAs tandem cells. Both spectral responses of the GaInP top cell and the GaAs middle cell in the thin-film GaInP/GaAs monolithic tandem cell were conserved. The Si cell performance has been improved by reducing the absorption loss in the GaAs substrate.

  3. Microbial diversity and carbon cycling in San Francisco Bay wetlands

    SciTech Connect (OSTI)

    Theroux, Susanna; Hartman, Wyatt; He, Shaomei; Tringe, Susannah

    2014-03-21

    Wetland restoration efforts in San Francisco Bay aim to rebuild habitat for endangered species and provide an effective carbon storage solution, reversing land subsidence caused by a century of industrial and agricultural development. However, the benefits of carbon sequestration may be negated by increased methane production in newly constructed wetlands, making these wetlands net greenhouse gas (GHG) sources to the atmosphere. We investigated the effects of wetland restoration on below-ground microbial communities responsible for GHG cycling in a suite of historic and restored wetlands in SF Bay. Using DNA and RNA sequencing, coupled with real-time GHG monitoring, we profiled the diversity and metabolic potential of wetland soil microbial communities. The wetland soils harbor diverse communities of bacteria and archaea whose membership varies with sampling location, proximity to plant roots and sampling depth. Our results also highlight the dramatic differences in GHG production between historic and restored wetlands and allow us to link microbial community composition and GHG cycling with key environmental variables including salinity, soil carbon and plant species.

  4. Chemical beam epitaxy growth of AlGaAs/GaAs tunnel junctions using trimethyl aluminium for multijunction solar cells

    SciTech Connect (OSTI)

    Paquette, B.; DeVita, M.; Turala, A.; Kolhatkar, G.; Boucherif, A.; Jaouad, A.; Aimez, V.; Ars, R.; Wilkins, M.; Wheeldon, J. F.; Walker, A. W.; Hinzer, K.; Fafard, S.

    2013-09-27

    AlGaAs/GaAs tunnel junctions for use in high concentration multijunction solar cells were designed and grown by chemical beam epitaxy (CBE) using trimethyl aluminium (TMA) as the p-dopant source for the AlGaAs active layer. Controlled hole concentration up to 4?10{sup 20} cm{sup ?3} was achieved through variation in growth parameters. Fabricated tunnel junctions have a peak tunneling current up to 6140 A/cm{sup 2}. These are suitable for high concentration use and outperform GaAs/GaAs tunnel junctions.

  5. 0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1eV)/GaInAs(0.7eV) Four-Junction Solar Cell

    SciTech Connect (OSTI)

    Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W.; Kurtz, S. R.

    2006-01-01

    We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga{sub 0.5}In{sub 0.5} P/GaAs/Ga{sub 0.75}In{sub 0.25}As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga{sub 0.75}In{sub 0.25}As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap Ga{sub x}In{sub 1-x}As fourth junction could be added to the three-junction structure for a four-junction cell whose efficiency could exceed 45% under concentration. Here, we present the initial development of the Ga{sub x}In{sub 1-x}As fourth junction. Junctions of various bandgaps ranging from 0.88 to 0.73 eV were grown, in order to study the effect of the different amounts of lattice mismatch. At a bandgap of 0.88 eV, junctions were obtained with very encouraging {approx}80% quantum efficiency, 57% fill factor, and 0.36 eV open-circuit voltage. The device performance degrades with decreasing bandgap (i.e., increasing lattice mismatch). We model the four-junction device efficiency vs. fourth junction bandgap to show that an 0.7-eV fourth-junction bandgap, while optimal if it could be achieved in practice, is not necessary; an 0.9-eV bandgap would still permit significant gains in multijunction cell efficiency while being easier to achieve than the lower-bandgap junction.

  6. Integrating AlGaN/GaN high electron mobility transistor with Si: A comparative study of integration schemes

    SciTech Connect (OSTI)

    Mohan, Nagaboopathy; Raghavan, Srinivasan; Manikant,; Soman, Rohith

    2015-10-07

    AlGaN/GaN high electron mobility transistor stacks deposited on a single growth platform are used to compare the most common transition, AlN to GaN, schemes used for integrating GaN with Si. The efficiency of these transitions based on linearly graded, step graded, interlayer, and superlattice schemes on dislocation density reduction, stress management, surface roughness, and eventually mobility of the 2D-gas are evaluated. In a 500 nm GaN probe layer deposited, all of these transitions result in total transmission electron microscopy measured dislocations densities of 1 to 3 × 10{sup 9}/cm{sup 2} and <1 nm surface roughness. The 2-D electron gas channels formed at an AlGaN-1 nm AlN/GaN interface deposited on this GaN probe layer all have mobilities of 1600–1900 cm{sup 2}/V s at a carrier concentration of 0.7–0.9 × 10{sup 13}/cm{sup 2}. Compressive stress and changes in composition in GaN rich regions of the AlN-GaN transition are the most effective at reducing dislocation density. Amongst all the transitions studied the step graded transition is the one that helps to implement this feature of GaN integration in the simplest and most consistent manner.

  7. Electron tunneling spectroscopy study of electrically active traps in AlGaN/GaN high electron mobility transistors

    SciTech Connect (OSTI)

    Yang, Jie Cui, Sharon; Ma, T. P.; Hung, Ting-Hsiang; Nath, Digbijoy; Krishnamoorthy, Sriram; Rajan, Siddharth

    2013-11-25

    We investigate the energy levels of electron traps in AlGaN/GaN high electron mobility transistors by the use of electron tunneling spectroscopy. Detailed analysis of a typical spectrum, obtained in a wide gate bias range and with both bias polarities, suggests the existence of electron traps both in the bulk of AlGaN and at the AlGaN/GaN interface. The energy levels of the electron traps have been determined to lie within a 0.5?eV band below the conduction band minimum of AlGaN, and there is strong evidence suggesting that these traps contribute to Frenkel-Poole conduction through the AlGaN barrier.

  8. Raman spectroscopy of InGaAs/GaAs nanoheterostructures δ-doped with Mn

    SciTech Connect (OSTI)

    Plankina, S. M.; Vikhrova, O. V.; Danilov, Yu. A.; Zvonkov, B. N.; Kalentyeva, I. L.; Nezhdanov, A. V.; Chunin, I. I.; Yunin, P. A.

    2015-01-15

    The results of complex studies of InGaAs/GaAs nanoheterostructures δ-doped with Mn are reported. The structures are grown by metal-organic vapor-phase epitaxy in combination with laser deposition. By confocal Raman spectroscopy, it is shown that the low-temperature δ-doped GaAs cap layers are of higher crystal quality compared to uniformly doped layers. Scattering of light in the coupled phonon-plasmon mode is observed. The appearance of this mode is conditioned by the diffusion of manganese from the δ-layer. The thickness of the cap layer is found to be d{sub c} ≈ 9–20 nm, optimal for attainment of the highest photoluminescence intensity of the quantum well and the highest layer concentration of holes by doping with manganese.

  9. Efficiency enhancement of InGaN/GaN solar cells with nanostructures

    SciTech Connect (OSTI)

    Bai, J.; Yang, C. C.; Athanasiou, M.; Wang, T.

    2014-02-03

    We demonstrate InGaN/GaN multi-quantum-well solar cells with nanostructures operating at a wavelength of 520?nm. Nanostructures with a periodic nanorod or nanohole array are fabricated by means of modified nanosphere lithography. Under 1 sun air-mass 1.5 global spectrum illumination, a fill factor of 50 and an open circuit voltage of 1.9?V are achieved in spite of very high indium content in InGaN alloys usually causing degradation of crystal quality. Both the nanorod array and the nanohole array significantly improve the performance of solar cells, while a larger enhancement is observed for the nanohole array, where the conversion efficiency is enhanced by 51%.

  10. Electrical compensation by Ga vacancies in Ga{sub 2}O{sub 3} thin films

    SciTech Connect (OSTI)

    Korhonen, E.; Tuomisto, F.; Gogova, D.; Wagner, G.; Baldini, M.; Galazka, Z.; Schewski, R.; Albrecht, M.

    2015-06-15

    The authors have applied positron annihilation spectroscopy to study the vacancy defects in undoped and Si-doped Ga{sub 2}O{sub 3} thin films. The results show that Ga vacancies are formed efficiently during metal-organic vapor phase epitaxy growth of Ga{sub 2}O{sub 3} thin films. Their concentrations are high enough to fully account for the electrical compensation of Si doping. This is in clear contrast to another n-type transparent semiconducting oxide In{sub 2}O{sub 3}, where recent results show that n-type conductivity is not limited by cation vacancies but by other intrinsic defects such as O{sub i}.

  11. Graphene in ohmic contact for both n-GaN and p-GaN

    SciTech Connect (OSTI)

    Zhong, Haijian; Liu, Zhenghui; Shi, Lin; Xu, Gengzhao; Fan, Yingmin; Huang, Zengli; Wang, Jianfeng; Ren, Guoqiang; Xu, Ke

    2014-05-26

    The wrinkles of single layer graphene contacted with either n-GaN or p-GaN were found both forming ohmic contacts investigated by conductive atomic force microscopy. The local IV results show that some of the graphene wrinkles act as high-conductive channels and exhibiting ohmic behaviors compared with the flat regions with Schottky characteristics. We have studied the effects of the graphene wrinkles using density-functional-theory calculations. It is found that the standing and folded wrinkles with zigzag or armchair directions have a tendency to decrease or increase the local work function, respectively, pushing the local Fermi level towards n- or p-type GaN and thus improving the transport properties. These results can benefit recent topical researches and applications for graphene as electrode material integrated in various semiconductor devices.

  12. Photocapacitance study of type-II GaSb/GaAs quantum ring solar cells

    SciTech Connect (OSTI)

    Wagener, M. C.; Botha, J. R.; Carrington, P. J.; Krier, A.

    2014-01-07

    In this study, the density of states associated with the localization of holes in GaSb/GaAs quantum rings are determined by the energy selective charging of the quantum ring distribution. The authors show, using conventional photocapacitance measurements, that the excess charge accumulated within the type-II nanostructures increases with increasing excitation energies for photon energies above 0.9?eV. Optical excitation between the localized hole states and the conduction band is therefore not limited to the ?(k?=?0) point, with pseudo-monochromatic light charging all states lying within the photon energy selected. The energy distribution of the quantum ring states could consequently be accurately related from the excitation dependence of the integrated photocapacitance. The resulting band of localized hole states is shown to be well described by a narrow distribution centered 407?meV above the GaAs valence band maximum.

  13. A InGaN/GaN quantum dot green ({lambda}=524 nm) laser

    SciTech Connect (OSTI)

    Zhang Meng; Banerjee, Animesh; Lee, Chi-Sen; Hinckley, John M.; Bhattacharya, Pallab

    2011-05-30

    The characteristics of self-organized InGaN/GaN quantum dot lasers are reported. The laser heterostructures were grown on c-plane GaN substrates by plasma-assisted molecular beam epitaxy and the laser facets were formed by focused ion beam etching with gallium. Emission above threshold is characterized by a peak at 524 nm (green) and linewidth of 0.7 nm. The lowest measured threshold current density is 1.2 kA/cm{sup 2} at 278 K. The slope and wall plug efficiencies are 0.74 W/A and {approx}1.1%, respectively, at 1.3 kA/cm{sup 2}. The value of T{sub 0}=233 K in the temperature range of 260-300 K.

  14. Analysis of defects in GaAsN grown by chemical beam epitaxy on high index GaAs substrates

    SciTech Connect (OSTI)

    Bouzazi, Boussairi; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi

    2013-09-27

    The lattice defects in GaAsN grown by chemical beam epitaxy on GaAs 311B and GaAs 10A toward [110] were characterized and discussed by using deep level transient spectroscopy (DLTS) and on the basis of temperature dependence of the junction capacitances (C{sub J}). In one hand, GaAsN films grown on GaAs 311B and GaAs 10A showed n-type and p-type conductivities, respectively although the similar and simultaneous growth conditions. This result is indeed in contrast to the common known effect of N concentration on the type of conductivity, since the surface 311B showed a significant improvement in the incorporation of N. Furthermore, the temperature dependence of C{sub J} has shown that GaAs 311B limits the formation of N-H defects. In the other hand, the energy states in the forbidden gap of GaAsN were obtained. Six electron traps, E1 to E6, were observed in the DLTS spectrum of GaAsN grown on GaAs 311B, with apparent activation energies of 0.02, 0.14, 0.16, 0.33, 0.48, and 0.74 eV below the bottom edge of the conduction band, respectively. In addition, four hole traps, H1 to H4, were observed in the DLTS spectrum of GaAsN grown on GaAs 10A, with energy depths of 0.13, 0.20, 0.39, and 0.52 eV above the valence band maximum of the alloy, respectively. Hence, the surface morphology of the GaAs substrate was found to play a key factor role in clarifying the electrical properties of GaAsN grown by CBE.

  15. Refractive index of erbium doped GaN thin films

    SciTech Connect (OSTI)

    Alajlouni, S.; Sun, Z. Y.; Li, J.; Lin, J. Y.; Jiang, H. X.; Zavada, J. M.

    2014-08-25

    GaN is an excellent host for erbium (Er) to provide optical emission in the technologically important as well as eye-safe 1540 nm wavelength window. Er doped GaN (GaN:Er) epilayers were synthesized on c-plane sapphire substrates using metal organic chemical vapor deposition. By employing a pulsed growth scheme, the crystalline quality of GaN:Er epilayers was significantly improved over those obtained by conventional growth method of continuous flow of reaction precursors. X-ray diffraction rocking curve linewidths of less than 300 arc sec were achieved for the GaN (0002) diffraction peak, which is comparable to the typical results of undoped high quality GaN epilayers and represents a major improvement over previously reported results for GaN:Er. Spectroscopic ellipsometry was used to determine the refractive index of the GaN:Er epilayers in the 1540 nm wavelength window and a linear dependence on Er concentration was found. The observed refractive index increase with Er incorporation and the improved crystalline quality of the GaN:Er epilayers indicate that low loss GaN:Er optical waveguiding structures are feasible.

  16. Application of the ASME code in the design of the GA-4 and GA-9 casks

    SciTech Connect (OSTI)

    Mings, W.J. ); Koploy, M.A. )

    1992-01-01

    General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

  17. Application of the ASME code in the design of the GA-4 and GA-9 casks

    SciTech Connect (OSTI)

    Mings, W.J.; Koploy, M.A.

    1992-08-01

    General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

  18. Photoluminescence studies of individual and few GaSb/GaAs quantum rings

    SciTech Connect (OSTI)

    Young, M. P.; Woodhead, C. S.; Roberts, J.; Noori, Y. J.; Noble, M. T.; Krier, A.; Hayne, M.; Young, R. J.; Smakman, E. P.; Koenraad, P. M.

    2014-11-15

    We present optical studies of individual and few GaSb quantum rings embedded in a GaAs matrix. Contrary to expectation for type-II confinement, we measure rich spectra containing sharp lines. These lines originate from excitonic recombination and are observed to have resolution-limited full-width at half maximum of 200 ?eV. The detail provided by these measurements allows the characteristic type-II blueshift, observed with increasing excitation power, to be studied at the level of individual nanostructures. These findings are in agreement with hole-charging being the origin of the observed blueshift.

  19. 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.; Igusa, R.; Iwamoto, S.; Arakawa, Y.

    2014-09-15

    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.

  20. Origins of ion irradiation-induced Ga nanoparticle motion on GaAs surfaces

    SciTech Connect (OSTI)

    Kang, M.; Wu, J. H.; Chen, H. Y.; Thornton, K.; Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Beskin, I. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

    2013-08-12

    We have examined the origins of ion irradiation-induced nanoparticle (NP) motion. Focused-ion-beam irradiation of GaAs surfaces induces random walks of Ga NPs, which are biased in the direction opposite to that of ion beam scanning. Although the instantaneous NP velocities are constant, the NP drift velocities are dependent on the off-normal irradiation angle, likely due to a difference in surface non-stoichiometry induced by the irradiation angle dependence of the sputtering yield. It is hypothesized that the random walks are initiated by ion irradiation-induced thermal fluctuations, with biasing driven by anisotropic mass transport.

  1. Make Energy at The Bay Area Maker Faire | Department of Energy

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

    Make Energy at The Bay Area Maker Faire Make Energy at The Bay Area Maker Faire Addthis Representatives from the Department of Energy's National Labs, the Office of Energy Efficiency and Renewable Energy (EERE), the Advanced Research Projects Agency (ARPA-E) and the Office of Technology Transitions (OTT) were on hand at the first-ever Make | ENERGY Pavilion at the Bay Area Maker Faire May 20-22, 2016, at the San Mateo County Event Center. Watch this video to learn more

  2. DOE - Office of Legacy Management -- W R Grace Co - Curtis Bay - MD 01

    Office of Legacy Management (LM)

    Co - Curtis Bay - MD 01 FUSRAP Considered Sites W.R. Grace Co., MD Alternate Name(s): W.R. Grace Rare Earths, Inc. Davison Chemical Division Curtis Bay Plant MD.01-2 MD.01-3 Location: Curtis Bay, Baltimore, Maryland MD.01-2 Historical Operations: Conducted developmental research and thorium extraction from monazite ore for AEC. MD.01-6 Eligibility Determination: Eligible MD.01-2 Radiological Survey(s): Assessment Surveys MD.01-3 MD.01-4 MD.01-5 MD.01-6 Site Status: Cleanup in progress by U.S.

  3. GaP/Si heterojunction Solar Cells

    SciTech Connect (OSTI)

    Saive, R.; Chen, C.; Emmer, H.; Atwater, H.

    2015-05-11

    Improving the efficiency of solar cells requires the introduction of novel device concepts. Recent developments have shown that in Si solar cell technology there is still room for tremendous improvement. Using the heterojunction with intrinsic thin layer (HIT) approach 25.6 % power conversion efficiency was achieved. However, a-Si as a window and passivation layer comes with disadvantages as a-Si shows low conductivity and high parasitic absorption. Therefore, it is likely that using a crystalline material as window layer with high band gab and high mobility can further improve efficiency. We have studied GaP grown by MOCVD on Si with (001) and (112) orientation. We obtained crystalline layers with carrier mobility around 100 cm2/Vs and which passivate Si as confirmed by carrier lifetime measurements. We performed band alignment studies by X-ray photoelectron spectroscopy yielding a valence band offset of 0.3 eV. Comparing this value with the Schottky-model leads to an interface dipole of 0.59 eV. The open circuit voltage increases with increasing doping and is consistent with the theoretical open circuit voltage deduced from work function difference and interface dipole. We obtain an open circuit voltage of 0.38 V for n-doped GaP with doping levels in the order of 10^17 1/cm^3. In our next steps we will increase the doping level further in order to gain higher open circuit voltage. We will discuss the implications of these findings for GaP/Si heterojunction solar cells.

  4. Development of a Hydrodynamic and Transport model of Bellingham Bay in Support of Nearshore Habitat Restoration

    SciTech Connect (OSTI)

    Wang, Taiping; Yang, Zhaoqing; Khangaonkar, Tarang

    2010-04-22

    In this study, a hydrodynamic model based on the unstructured-grid finite volume coastal ocean model (FVCOM) was developed for Bellingham Bay, Washington. The model simulates water surface elevation, velocity, temperature, and salinity in a three-dimensional domain that covers the entire Bellingham Bay and adjacent water bodies, including Lummi Bay, Samish Bay, Padilla Bay, and Rosario Strait. The model was developed using Pacific Northwest National Laboratorys high-resolution Puget Sound and Northwest Straits circulation and transport model. A sub-model grid for Bellingham Bay and adjacent coastal waters was extracted from the Puget Sound model and refined in Bellingham Bay using bathymetric light detection and ranging (LIDAR) and river channel cross-section data. The model uses tides, river inflows, and meteorological inputs to predict water surface elevations, currents, salinity, and temperature. A tidal open boundary condition was specified using standard National Oceanic and Atmospheric Administration (NOAA) predictions. Temperature and salinity open boundary conditions were specified based on observed data. Meteorological forcing (wind, solar radiation, and net surface heat flux) was obtained from NOAA real observations and National Center for Environmental Prediction North American Regional Analysis outputs. The model was run in parallel with 48 cores using a time step of 2.5 seconds. It took 18 hours of cpu time to complete 26 days of simulation. The model was calibrated with oceanographic field data for the period of 6/1/2009 to 6/26/2009. These data were collected specifically for the purpose of model development and calibration. They include time series of water-surface elevation, currents, temperature, and salinity as well as temperature and salinity profiles during instrument deployment and retrieval. Comparisons between model predictions and field observations show an overall reasonable agreement in both temporal and spatial scales. Comparisons of

  5. Little Traverse Bay Bands of Odawa Indians- 2005 Project

    Broader source: Energy.gov [DOE]

    The Little Traverse Bay Bands of Odawa Indians is located in the northern part of lower Michigan on approximately 590 acres of land. The tribe originally had no consistent vision or strategic plan concerning its energy use. This project had three objectives. The first objective was to produce a comprehensive energy plan for the tribe. The second objective was to create an energy organization and tribal energy code. The third objective was to increase the capacity of the tribe for better understanding (through active tribal participation), capability, knowledge and awareness of energy issues through bimonthly articles in the tribal newsletter and two energy workshops. The vision, strategic plan, and code will provide the focus, direction and guidelines as the tribe seeks to develop renewable energy and energy efficiency.

  6. Distributed bragg reflector using AIGaN/GaN

    DOE Patents [OSTI]

    Waldrip, Karen E.; Lee, Stephen R.; Han, Jung

    2004-08-10

    A supported distributed Bragg reflector or superlattice structure formed from a substrate, a nucleation layer deposited on the substrate, and an interlayer deposited on the nucleation layer, followed by deposition of (Al,Ga,B)N layers or multiple pairs of (Al,Ga,B)N/(Al,Ga,B)N layers, where the interlayer is a material selected from AlN, Al.sub.x Ga.sub.1-x N, and AlBN with a thickness of approximately 20 to 1000 angstroms. The interlayer functions to reduce or eliminate the initial tensile growth stress, thereby reducing cracking in the structure. Multiple interlayers utilized in an AlGaN/GaN DBR structure can eliminate cracking and produce a structure with a reflectivity value greater than 0.99.

  7. High-Efficiency GaInP/GaAs Tandem Solar Cells

    SciTech Connect (OSTI)

    Bertness, K. A.; Friedman, D. J.; Kurtz, S. R.; Kibbler, A. E.; Cramer, C.; Olson, J. M.

    1996-09-01

    GaInP/GaAs tandem solar cells have achieved efficiencies between 25.7-30.2%, depending on illumination conditions. The efficiencies are the highest confirmed two-terminal values measured for any solar cell within each standard illumination category. The monolithic, series-connected design of the tandem cells allows them to be substituted for silicon or gallium arsenide cells in photovoltaic panel systems with minimal design changes. The advantages of using GaInP/GaAs tandem solar cells in space and terrestrial applications are discussed primarily in terms of the reduction in balance-of-system costs that accrues when using a higher efficiency cell. The new efficiency values represent a significant improvement over previous efficiencies for this materials system, and we identify grid design, back interface passivation, and top interface passivation as the three key factors leading to this improvement. In producing the high-efficiency cells, we have addressed nondestructive diagnostics and materials growth reproducibility as well as peak cell performance.

  8. High-efficiency GaInP/GaAs tandem solar cells

    SciTech Connect (OSTI)

    Bertness, K.A.; Friedman, D.J.; Kurtz, S.R.; Kibbler, A.E.; Kramer, C.; Olson, J.M.

    1994-12-01

    GaInP/GaAs tandem solar cells have achieved new record efficiencies, specifically 25.7% under air-mass 0 (AM0) illumination, 29.5% under AM 1.5 global (AM1.5G) illumination, and 30.2% at 140-180x concentration under AM 1.5 direct (AM1.5D) illumination. These values are the highest two-terminal efficiencies achieved by any solar cell under these illumination conditions. The monolithic, series-connected design of the tandem cells allows them to be substituted for silicon or gallium arsenide cells in photovoltaic panel systems with minimal design changes. The advantages of using GaInP/GaAs tandem solar cells in space and terrestrial applications are discussed primarily in terms of the reduction in balance-of-system costs that accrues when using a higher efficiency cell. The new efficiency values represent a significant improvement over previous efficiencies for this materials system, and we identify grid design, back interface passivation, and top interface passivation as the three key factors leading to this improvement. In producing the high-efficiency cells, we have addressed nondestructive diagnostics and materials growth reproducibility as well as peak cell performance. 31 refs.

  9. AlGaAs/InGaAlP tunnel junctions for multijunction solar cells

    SciTech Connect (OSTI)

    SHARPS,P.R.; LI,N.Y.; HILLS,J.S.; HOU,H.; CHANG,PING-CHIH; BACA,ALBERT G.

    2000-05-16

    Optimization of GaInP{sub 2}/GaAs dual and GaInP{sub 2}/GaAs/Ge triple junction cells, and development of future generation monolithic multi-junction cells will involve the development of suitable high bandgap tunnel junctions. There are three criteria that a tunnel junction must meet. First, the resistance of the junction must be kept low enough so that the series resistance of the overall device is not increased. For AMO, 1 sun operation, the tunnel junction resistance should be below 5 x 10{sup {minus}2} {Omega}-cm. Secondly, the peak current density for the tunnel junction must also be larger than the J{sub sc} of the cell so that the tunnel junction I-V curve does not have a deleterious effect on the I-V curve of the multi-junction device. Finally, the tunnel junction must be optically transparent, i.e., there must be a minimum of optical absorption of photons that will be collected by the underlying subcells. The paper reports the investigation of four high bandgap tunnel junctions grown by metal-organic chemical vapor deposition.

  10. TJ Solar Cell (GaInP/GaAs/Ge Ultrahigh-Efficiency Solar Cells

    SciTech Connect (OSTI)

    Friedman, Daniel

    2002-04-17

    This talk will discuss recent developments in III-V multijunction photovoltaic technology which have led to the highest-efficiency solar cells ever demonstrated. The relationship between the materials science of III-V semiconductors and the achievement of record solar cell efficiencies will be emphasized. For instance, epitaxially-grown GAInP has been found to form a spontaneously-ordered GaP/InP (111) superlattice. This ordering affects the band gap of the material, which in turn affects the design of solar cells which incorporate GaInP. For the next generation of ultrahigh-efficiency III-V solar cells, we need a new semiconductor which is lattice-matched to GaAs, has a band gap of 1 eV, and has long minority-carrier diffusion lengths. Out of a number of candidate materials, the recently-discovered alloy GaInNAs appears to have the greatest promise. This material satisfies the first two criteria, but has to date shown very low diffusion lengths, a problem which is our current focus in the development of these next-generation cells.

  11. Multijunction GaInP/GaInAs/Ge solar cells with Bragg reflectors

    SciTech Connect (OSTI)

    Emelyanov, V. M. Kalyuzhniy, N. A.; Mintairov, S. A.; Shvarts, M. Z.; Lantratov, V. M.

    2010-12-15

    Effect of subcell parameters on the efficiency of GaInP/Ga(In)As/Ge tandem solar cells irradiated with 1-MeV electrons at fluences of up to 3 x 10{sup 15} cm{sup -2} has been theoretically studied. The optimal thicknesses of GaInP and GaInAs subcells, which provide the best photocurrent matching at various irradiation doses in solar cells with and without built-in Bragg reflectors, were determined. The dependences of the photoconverter efficiency on the fluence of 1-MeV electrons and on the time of residence in the geostationary orbit were calculated for structures optimized to the beginning and end of their service lives. It is shown that the optimization of the subcell heterostructures for a rated irradiation dose and the introduction of Bragg reflectors into the structure provide a 5% overall increase in efficiency for solar cells operating in the orbit compared with unoptimized cells having no Bragg reflector.

  12. Localized corrosion of GaAs surfaces and formation of porous GaAs

    SciTech Connect (OSTI)

    Schmuki, P.; Vitus, C.M.; Isaacs, H.S.; Fraser, J.; Graham, M.J.

    1995-12-01

    The present work deals with pitting corrosion of p- and n-type GaAs (100). Pit growth can be electrochemically initiated on both conduction types in chloride-containing solutions and leads after extended periods of time to the formation of a porous GaAs structure. In the case of p-type material, localized corrosion is only observed if a passivating film is present on the surface, otherwise -- e.g. in acidic solutions -- the material suffers from a uniform attack (electropolishing) which is independent of the anion present. In contrast, pitting corrosion of n-type material can be triggered independent of the presence of an oxide film. This is explained in terms of the different current limiting factor for the differently doped materials (oxide film in the case of the p- and a space charge layer in the case of the n-GaAs). The porous structure was characterized by SEM, EDX and AES, and consists mainly of GaAs. From scratch experiments it is clear that the pit initiation process is strongly influenced by surface defects. For n-type material, AFM investigations show that light induced roughening of the order of several hundred nm occurs under non-passivating conditions. This nm- scale roughening however does not affect the pitting process.

  13. fe0013961-GaTech | netl.doe.gov

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

    Performer Georgia Tech Research Corporation, Atlanta GA 30332 Background While earlier research focused on the properties of the hydrate mass per se (Sloan Jr and Koh 2007), ...

  14. Photoluminescence from GaAs nanodisks fabricated by using combination...

    Office of Scientific and Technical Information (OSTI)

    GaAs nanodisks fabricated by using combination of neutral beam etching and atomic hydrogen-assisted molecular beam epitaxy regrowth Citation Details In-Document Search Title:...

  15. Inverse spin Hall effect in Pt/(Ga,Mn)As

    SciTech Connect (OSTI)

    Nakayama, H.; Chen, L.; Chang, H. W.; Ohno, H.; Matsukura, F.

    2015-06-01

    We investigate dc voltages under ferromagnetic resonance in a Pt/(Ga,Mn)As bilayer structure. A part of the observed dc voltage is shown to originate from the inverse spin Hall effect. The sign of the inverse spin Hall voltage is the same as that in Py/Pt bilayer structure, even though the stacking order of ferromagnetic and nonmagnetic layers is opposite to each other. The spin mixing conductance at the Pt/(Ga,Mn)As interface is determined to be of the order of 10{sup 19 }m{sup −2}, which is about ten times greater than that of (Ga,Mn)As/p-GaAs.

  16. Atomic structure of defects in GaN:Mg grown with Ga polarity

    SciTech Connect (OSTI)

    Liliental-Weber, Z.; Tomaszewicz, T.; Zakharov, D.; Jasinski, J.; O'Keefe, M.A.; Hautakangas, S.; Laakso, A.; Saarinen, K.

    2003-11-25

    Electron microscope phase images, produced by direct reconstruction of the scattered electron wave from a focal series of high-resolution images, were used to determine the nature of defects formed in GaN:Mg crystals. We studied bulk crystals grown from dilute solutions of atomic nitrogen in liquid gallium at high pressure and thin films grown by the MOCVD method. All the crystals were grown with Ga-polarity. In both types of samples the majority of defects were three dimensional Mg-rich hexagonal pyramids with bases on the (0001) plane and six walls on {l_brace}11{und 2}3{r_brace} planes seen in cross-section as triangulars. Some other defects appear in cross-section as trapezoidal (rectangular) defects as a result of presence of truncated pyramids. Both type of defects have hollow centers. They are decorated by Mg on all six side walls and a base. The GaN which grows inside on the defect walls shows polarity inversion. It is shown that change of polarity starts from the defect tip and propagates to the base, and that the stacking sequence changes from ab in the matrix to bc inside the defect. Exchange of the Ga sublattice with the N sublattice within the defect leads to 0.6 {+-} 0.2{angstrom} displacement between Ga sublattices outside and inside the defects. It is proposed that lateral overgrowth of the cavities formed within the defect takes place to restore matrix polarity on the defect base.

  17. Deep level defects in n-type GaAsBi and GaAs grown at low temperatures

    SciTech Connect (OSTI)

    Mooney, P. M.; Watkins, K. P.; Jiang, Zenan; Basile, A. F.; Lewis, R. B.; Bahrami-Yekta, V.; Masnadi-Shirazi, M.; Beaton, D. A.; Tiedje, T.

    2013-04-07

    Deep level defects in n-type GaAs{sub 1-x}Bi{sub x} having 0 < x < 0.012 and GaAs grown by molecular beam epitaxy (MBE) at substrate temperatures between 300 and 400 Degree-Sign C have been investigated by Deep Level Capacitance Spectroscopy. Incorporating Bi suppresses the formation of an electron trap with activation energy 0.40 eV, thus reducing the total trap concentration in dilute GaAsBi layers by more than a factor of 20 compared to GaAs grown under the same conditions. We find that the dominant traps in dilute GaAsBi layers are defect complexes involving As{sub Ga}, as expected for MBE growth at these temperatures.

  18. Au impact on GaAs epitaxial growth on GaAs (111){sub B} substrates in molecular beam epitaxy

    SciTech Connect (OSTI)

    Liao, Zhi-Ming; Chen, Zhi-Gang; Xu, Hong-Yi; Guo, Ya-Nan; Sun, Wen; Zhang, Zhi; Yang, Lei; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin; Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Queensland 4072

    2013-02-11

    GaAs growth behaviour under the presence of Au nanoparticles on GaAs {l_brace}111{r_brace}{sub B} substrate is investigated using electron microscopy. It has been found that, during annealing, enhanced Ga surface diffusion towards Au nanoparticles leads to the GaAs epitaxial growth into {l_brace}113{r_brace}{sub B} faceted triangular pyramids under Au nanoparticles, governed by the thermodynamic growth, while during conventional GaAs growth, growth kinetics dominates, resulting in the flatted triangular pyramids at high temperature and the epitaxial nanowires growth at relatively low temperature. This study provides an insight of Au nanoparticle impact on GaAs growth, which is critical for understanding the formation mechanisms of semiconductor nanowires.

  19. Deep level centers and their role in photoconductivity transients of InGaAs/GaAs quantum dot chains

    SciTech Connect (OSTI)

    Kondratenko, S. V. Vakulenko, O. V.; Mazur, Yu. I. Dorogan, V. G.; Marega, E.; Benamara, M.; Ware, M. E.; Salamo, G. J.

    2014-11-21

    The in-plane photoconductivity and photoluminescence are investigated in quantum dot-chain InGaAs/GaAs heterostructures. Different photoconductivity transients resulting from spectrally selecting photoexcitation of InGaAs QDs, GaAs spacers, or EL2 centers were observed. Persistent photoconductivity was observed at 80?K after excitation of electron-hole pairs due to interband transitions in both the InGaAs QDs and the GaAs matrix. Giant optically induced quenching of in-plane conductivity driven by recharging of EL2 centers is observed in the spectral range from 0.83?eV to 1.0?eV. Conductivity loss under photoexcitation is discussed in terms of carrier localization by analogy with carrier distribution in disordered media.

  20. MHK Projects/OpenHydro Bay of Fundy Nova Scotia CA | Open Energy...

    Open Energy Info (EERE)

    Phase Phase 1 Project Details OpenHydro is working with Canadian utility Nova Scotia Power to create a tidal demonstration project in the Bay of Fundy. Following successful...

  1. Self-catalyzed growth of dilute nitride GaAs/GaAsSbN/GaAs core-shell nanowires by molecular beam epitaxy

    SciTech Connect (OSTI)

    Kasanaboina, Pavan Kumar; Ahmad, Estiak; Li, Jia; Iyer, Shanthi; Reynolds, C. Lewis; Liu, Yang

    2015-09-07

    Bandgap tuning up to 1.3 μm in GaAsSb based nanowires by incorporation of dilute amount of N is reported. Highly vertical GaAs/GaAsSbN/GaAs core-shell configured nanowires were grown for different N contents on Si (111) substrates using plasma assisted molecular beam epitaxy. X-ray diffraction analysis revealed close lattice matching of GaAsSbN with GaAs. Micro-photoluminescence (μ-PL) revealed red shift as well as broadening of the spectra attesting to N incorporation in the nanowires. Replication of the 4K PL spectra for several different single nanowires compared to the corresponding nanowire array suggests good compositional homogeneity amongst the nanowires. A large red shift of the Raman spectrum and associated symmetric line shape in these nanowires have been attributed to phonon localization at point defects. Transmission electron microscopy reveals the dominance of stacking faults and twins in these nanowires. The lower strain present in these dilute nitride nanowires, as opposed to GaAsSb nanowires having the same PL emission wavelength, and the observation of room temperature PL demonstrate the advantage of the dilute nitride system offers in the nanowire configuration, providing a pathway for realizing nanoscale optoelectronic devices in the telecommunication wavelength region.

  2. An inverted AlGaAs/GaAs patterned-Ge tunnel junction cascade concentrator solar cell

    SciTech Connect (OSTI)

    Venkatasubramanian, R. )

    1993-01-01

    This report describes work to develop inverted-grown Al[sub 0.34]Ga[sub 0.66]As/GaAs cascades. Several significant developments are reported on as follows: (1) The AM1.5 1-sun total-area efficiency of the top Al[sub 0.34]Ga[sub 0.66]As cell for the cascade was improved from 11.3% to 13.2% (NREL measurement [total-area]). (2) The cycled'' organometallic vapor phase epitaxy growth (OMVPE) was studied in detail utilizing a combination of characterization techniques including Hall-data, photoluminescence, and secondary ion mass spectroscopy. (3) A technique called eutectic-metal-bonding (EMB) was developed by strain-free mounting of thin GaAs-AlGaAs films (based on lattice-matched growth on Ge substrates and selective plasma etching of Ge substrates) onto Si carrier substrates. Minority-carrier lifetime in an EMB GaAs double-heterostructure was measured as high as 103 nsec, the highest lifetime report for a freestanding GaAs thin film. (4) A thin-film, inverted-grown GaAs cell with a 1-sun AM1.5 active-area efficiency of 20.3% was obtained. This cell was eutectic-metal-bonded onto Si. (5) A thin-film inverted-grown, Al[sub 0.34]Ga[sub 0.66]As/GaAs cascade with AM1.5 efficiency of 19.9% and 21% at 1-sun and 7-suns, respectively, was obtained. This represents an important milestone in the development of an AlGaAs/GaAs cascade by OMVPE utilizing a tunnel interconnect and demonstrates a proof-of-concept for the inverted-growth approach.

  3. Energy Secretary Steven Chu to Travel to Bay Area to Highlight State of the

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

    Union Address, Commitment to Clean Energy | Department of Energy Bay Area to Highlight State of the Union Address, Commitment to Clean Energy Energy Secretary Steven Chu to Travel to Bay Area to Highlight State of the Union Address, Commitment to Clean Energy January 31, 2012 - 7:38pm Addthis Washington, D.C. - As part of the Energy Department's ongoing efforts to highlight President Obama's State of the Union address and discuss the Obama Administration's commitment to American energy

  4. Importance of Carolina Bays to the Avifauna of Pinelands in the Southeastern United States.

    SciTech Connect (OSTI)

    Czapka, Stephen, J.; Kilgo, John, C.

    2011-07-01

    Abstract - Past anthropogenic activity has led to the destruction or alteration of Carolina bay wetlands throughout the southeastern United States. Presently, urban development, combined with a 2001 ruling by the US Supreme Court relaxing protection of isolated wetlands, poses an increasing threat to these and other isolated wetland systems; however, little information exists on the importance of these wetland systems to birds. We compared breeding and wintering bird communities of upland pine (Pinus spp.) forests with and without Carolina bays. Estimated species richness was greater in pine forests with Carolina bays than without during the winter (31.7 ± 1.3 [mean ± SE] vs. 26.9 ± 1.2; P = 0.027), but not in the breeding season (27.9 ± 2.2 vs. 26.3 ± 2.2; P = 0.644). Total relative abundance did not differ between pine forests with Carolina bays and those without in either the breeding (148.0 ± 16.0 vs. 129.4 ± 10.4 birds/40 ha; P = 0.675) or winter (253.0 ± 36.4 vs. 148.8 ± 15.1 birds/40 ha; P = 0.100) seasons. However, 23 species, 43% of which were wetland-dependent, were observed only in pine forests with bays during the breeding season, and 20 species, 30% of which were wetland-dependent, were observed only in such sites during winter. In contrast, only 6 and 1 species were observed only in pine forests without bays during the breeding and winter seasons, respectively, indicating that few species were negatively affected by the presence of bays. Thus, Carolina bays appear to enrich the avifauna of pine forests in the southeastern United States.

  5. Comprehensive characterization report on Winter Quarters Bay, McMurdo Station, Antarctica

    SciTech Connect (OSTI)

    Crockett, A.B.; White, G.J.

    1997-01-01

    Winter Quarters Bay is a small embayment located adjacent to the United States largest base in Antarctica, McMurdo Station. McMurdo Station, which is managed by the National Science Foundation`s Office of Polar Programs, was constructed in 1955, has been in constant use since that time, and has a population of about 1,000 persons during the summer and about 250 people for the winter. The bay offers shelter for ships and an ice dock is used during January and February to off load fuel and cargo. During earlier times, trash from the McMurdo Station was piled on the steep shoreline of the bay, doused with several thousand gallons of fuel and ignited. That practice has ceased and the site has been regraded to cover the waste. The bottom of the bay is littered with drums, equipment, tanks, tires, all sorts of metal objects, cables, etc., especially the southeastern side where dumping took place. The sediments are gravel in some places yet fine and fluid at other sites with coarse particles intermixed. The original benthic community is not well recorded but significant ecological changes have occurred. Sediments are contaminated with PCBs, metals, and hydrocarbon fuels. This report summarizes available information on Winter Quarters Bay and was originally intended to be used by workshop participants to become familiar with the bay prior to becoming updated with unpublished data by various Antarctic investigators. The proposed workshop was to assist the National Science Foundation in determining whether and how the bay should be remediated and to develop an integrated research plan if additional data were needed. However, plans changed, the workshop was never conducted, but the briefing report was prepared. Most of this report reviews and summarizes other published data. The only new data are those from the Idaho National Engineering and Environmental Laboratory`s investigation into the distribution of organic contaminants in the bay and sediment toxicity testing.

  6. BayeSED: A GENERAL APPROACH TO FITTING THE SPECTRAL ENERGY DISTRIBUTION OF GALAXIES

    SciTech Connect (OSTI)

    Han, Yunkun; Han, Zhanwen E-mail: zhanwenhan@ynao.ac.cn

    2014-11-01

    We present a newly developed version of BayeSED, a general Bayesian approach to the spectral energy distribution (SED) fitting of galaxies. The new BayeSED code has been systematically tested on a mock sample of galaxies. The comparison between the estimated and input values of the parameters shows that BayeSED can recover the physical parameters of galaxies reasonably well. We then applied BayeSED to interpret the SEDs of a large K{sub s} -selected sample of galaxies in the COSMOS/UltraVISTA field with stellar population synthesis models. Using the new BayeSED code, a Bayesian model comparison of stellar population synthesis models has been performed for the first time. We found that the 2003 model by Bruzual and Charlot, statistically speaking, has greater Bayesian evidence than the 2005 model by Maraston for the K{sub s} -selected sample. In addition, while setting the stellar metallicity as a free parameter obviously increases the Bayesian evidence of both models, varying the initial mass function has a notable effect only on the Maraston model. Meanwhile, the physical parameters estimated with BayeSED are found to be generally consistent with those obtained using the popular grid-based FAST code, while the former parameters exhibit more natural distributions. Based on the estimated physical parameters of the galaxies in the sample, we qualitatively classified the galaxies in the sample into five populations that may represent galaxies at different evolution stages or in different environments. We conclude that BayeSED could be a reliable and powerful tool for investigating the formation and evolution of galaxies from the rich multi-wavelength observations currently available. A binary version of the BayeSED code parallelized with Message Passing Interface is publicly available at https://bitbucket.org/hanyk/bayesed.

  7. Building America Whole-House Solutions for Existing HomesBay Ridge Gardens

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

    - Mixed Humid Affordable Multifamily Housing Deep Energy Retrofit, Annapolis, Maryland (Fact Sheet) | Department of Energy HomesBay Ridge Gardens - Mixed Humid Affordable Multifamily Housing Deep Energy Retrofit, Annapolis, Maryland (Fact Sheet) Building America Whole-House Solutions for Existing HomesBay Ridge Gardens - Mixed Humid Affordable Multifamily Housing Deep Energy Retrofit, Annapolis, Maryland (Fact Sheet) Approximately 43% energy savings are achieved in a 1970s multifamily

  8. DC characteristics of OMVPE-grown N-p-n InGaP/InGaAsN DHBTs

    SciTech Connect (OSTI)

    Li, N.Y.; Chang, P.C.; Baca, A.G.; Xie, X.M.; Sharps, P.R.; Hou, H.Q.

    2000-01-04

    The authors demonstrate, for the first time, a functional N-p-n heterojunction bipolar transistor using a novel material, InGaAsN, with a bandgap energy of 1.2eV as the p-type base layer. A 300{angstrom}-thick In{sub x}Ga{sub 1-x}As graded layer was introduced to reduce the conduction band offset at the p-type InGaAsN base and n-type GaAs collector junction. For an emitter size of 500 {mu}m{sup 2}, a peak current gain of 5.3 has been achieved.

  9. Evaluation of 1991-1992 Brood Overwinter-Reared Coho Released from Net Pens in Youngs Bay, Oregon : Final Completion Report Youngs Bay Terminal Fishery Project.

    SciTech Connect (OSTI)

    Hirose, Paul S.

    1997-01-01

    Funding from Bonneville Power Administration was provided to the Oregon Department of Fish and Wildlife and the Clatsop County Economic Development Council`s Fisheries Project to identify and develop terminal fishing opportunities. The 1991 and 1992 brood fingerling coho from Oregon Department of Fish and Wildlife hatcheries were successfully reared during the winter period to smolt stage in Youngs Bay utilizing floating net pens. Based on coded-wire-tag recoveries during 1991--93 from 2-week net-pen acclimation releases, total accountability of coho adults averaged 40,540 fish, with the Youngs Bay commercial harvest accounting for 39%. With reduced ocean harvest impacts during 1994 and 1995, 92% of 51,640 coho in 1994 and 68% of 23,599 coho in 1995 (based on coded-wire-tag recoveries) were accounted for in the Youngs Bay commercial fishery for combined 2-week and overwinter acclimation net-pen releases. Overwinter net-pen acclimation coho accounted for 35,063 and 15,775 coho adults in 1994 and 1995 with 93% and 68% accountable in the Youngs Bay commercial harvest. Based on coded-wire-tag recoveries, less than 1% of the adults resulting from releases at Youngs Bay net pens strayed to hatcheries, while none were recovered on spawning ground surveys during 1991--95. The highest survival rates were observed for 1991 and 1992 brood overwinter coho released in early May. Time of release, not rearing strategy, appears to be the determining factor affecting survival in Youngs Bay.

  10. Reliability of AlGaN/GaN high electron mobility transistors on low dislocation density bulk GaN substrate: Implications of surface step edges

    SciTech Connect (OSTI)

    Killat, N. E-mail: Martin.Kuball@bristol.ac.uk; Montes Bajo, M.; Kuball, M. E-mail: Martin.Kuball@bristol.ac.uk; Paskova, T.; Materials Science and Engineering Department, North Carolina State University, Raleigh, North Carolina 27695 ; Evans, K. R.; Leach, J.; Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 ; Li, X.; Özgür, Ü.; Morkoç, H.; Chabak, K. D.; Crespo, A.; Gillespie, J. K.; Fitch, R.; Kossler, M.; Walker, D. E.; Trejo, M.; Via, G. D.; Blevins, J. D.

    2013-11-04

    To enable gaining insight into degradation mechanisms of AlGaN/GaN high electron mobility transistors, devices grown on a low-dislocation-density bulk-GaN substrate were studied. Gate leakage current and electroluminescence (EL) monitoring revealed a progressive appearance of EL spots during off-state stress which signify the generation of gate current leakage paths. Atomic force microscopy evidenced the formation of semiconductor surface pits at the failure location, which corresponds to the interaction region of the gate contact edge and the edges of surface steps.

  11. A monolithic white LED with an active region based on InGaN QWs separated by short-period InGaN/GaN superlattices

    SciTech Connect (OSTI)

    Tsatsulnikov, A. F. Lundin, W. V.; Sakharov, A. V.; Zavarin, E. E.; Usov, S. O.; Nikolaev, A. E.; Kryzhanovskaya, N. V.; Synitsin, M. A.; Sizov, V. S.; Zakgeim, A. L.; Mizerov, M. N.

    2010-06-15

    A new approach to development of effective monolithic white-light emitters is described based on using a short-period InGaN/GaN superlattice as a barrier layer in the active region of LED structures between InGaN quantum wells emitting in the blue and yellow-green spectral ranges. The optical properties of structures of this kind have been studied, and it is demonstrated that the use of such a superlattice makes it possible to obtain effective emission from the active region.

  12. Hardwood re-sprout control in hydrologically restored Carolina Bay depression wetlands.

    SciTech Connect (OSTI)

    Moser, Lee, Justin

    2009-06-01

    Carolina bays are isolated depression wetlands located in the upper coastal plain region of the eastern Unites States. Disturbance of this wetland type has been widespread, and many sites contain one or more drainage ditches as a result of agricultural conversion. Restoration of bays is of interest because they are important habitats for rare flora and fauna species. Previous bay restoration projects have identified woody competitors in the seedbank and re-sprouting as impediments to the establishment of herbaceous wetland vegetation communities. Three bays were hydrologically restored on the Savannah River Site, SC, by plugging drainage ditches. Residual pine/hardwood stands within the bays were harvested and the vegetative response of the seedbank to the hydrologic change was monitored. A foliar herbicide approved for use in wetlands (Habitat® (Isopropylamine salt of Imazapyr)) was applied on one-half of each bay to control red maple (Acer rubrum L.), sweet gum (Liquidambar styraciflua L.), and water oak (Quercus nigra L.) sprouting. The effectiveness of the foliar herbicide was tested across a hydrologic gradient in an effort to better understand the relationship between depth and duration of flooding, the intensity of hardwood re-sprout pressure, and the need for hardwood management practices such as herbicide application.

  13. Photoeffects in WO{sub 3}/GaAs electrode

    SciTech Connect (OSTI)

    Yoon, K.H.; Lee, J.W.; Cho, Y.S.; Kang, D.H.

    1996-12-01

    Photoeffects of a {ital p}-type GaAs coated with WO{sub 3} thin film have been investigated as a function of film thickness and photoresponse transients of the WO{sub 3}/GaAs electrode were studied. Also, these results were compared to those for a single {ital p}-type GaAs electrode. The photocurrent of the WO{sub 3}/GaAs electrode depended on the film thickness of the WO{sub 3}, showing an optimum photon efficiency for specimens of 800 A thickness. This is due to the existence of an effective interface state within the band gap which reduces trapping of carriers and facilitates carrier movement. For an 800-A-thick WO{sub 3} thin film deposited {ital p}-GaAs photoelectrode, the photogenerated electrons were found to move to an electrolyte at a higher positive onset potential compared with that of single {ital p}-type GaAs, which was confirmed as a result of transient behavior. {ital I}{endash}{ital V} and {ital C}{endash}{ital V} characteristics of the WO{sub 3}/GaAs electrode were also compared with those of a single {ital p}-type GaAs electrode. {copyright} {ital 1996 American Institute of Physics.}

  14. Long-wavelength shift and enhanced room temperature photoluminescence efficiency in GaAsSb/InGaAs/GaAs-based heterostructures emitting in the spectral range of 1.01.2??m due to increased charge carrier's localization

    SciTech Connect (OSTI)

    Kryzhkov, D. I. Yablonsky, A. N.; Morozov, S. V.; Aleshkin, V. Ya.; Krasilnik, Z. F.; Zvonkov, B. N.; Vikhrova, O. V.

    2014-11-28

    In this work, a study of the photoluminescence (PL) temperature dependence in quantum well GaAs/GaAsSb and double quantum well InGaAs/GaAsSb/GaAs heterostructures grown by metalorganic chemical vapor deposition with different parameters of GaAsSb and InGaAs layers has been performed. It has been demonstrated that in double quantum well InGaAs/GaAsSb/GaAs heterostructures, a significant shift of the PL peak to a longer-wavelength region (up to 1.2??m) and a considerable reduction in the PL thermal quenching in comparison with GaAs/GaAsSb structures can be obtained due to better localization of charge carriers in the double quantum well. For InGaAs/GaAsSb/GaAs heterostructures, an additional channel of radiative recombination with participation of the excited energy states in the quantum well, competing with the main ground-state radiative transition, has been revealed.

  15. Growth of GaN@InGaN Core-Shell and Au-GaN Hybrid Nanostructures for Energy Applications

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

    Kuykendall, Tevye; Aloni, Shaul; Jen-La Plante, Ilan; Mokari, Taleb

    2009-01-01

    We demonstrated a method to control the bandgap energy of GaN nanowires by forming GaN@InGaN core-shell hybrid structures using metal organic chemical vapor deposition (MOCVD). Furthermore, we show the growth of Au nanoparticles on the surface of GaN nanowires in solution at room temperature. The work shown here is a first step toward engineering properties that are crucial for the rational design and synthesis of a new class of photocatalytic materials. The hybrid structures were characterized by various techniques, including photoluminescence (PL), energy dispersive x-ray spectroscopy (EDS), transmission and scanning electron microscopy (TEM and SEM), and x-ray diffraction (XRD).

  16. Raman spectroscopy of GaP/GaNP core/shell nanowires

    SciTech Connect (OSTI)

    Dobrovolsky, A.; Chen, W. M.; Buyanova, I. A.; Sukrittanon, S.; Kuang, Y. J.; Tu, C. W.

    2014-11-10

    Raman spectroscopy is employed to characterize structural and phonon properties of GaP/GaNP core/shell nanowires (NWs) grown by molecular beam epitaxy on Si substrates. According to polarization-dependent measurements performed on single NWs, the dominant Raman modes associated with zone-center optical phonons obey selection rules in a zinc-blende lattice, confirming high crystalline quality of the NWs. Two additional modes at 360 and 397 cm{sup −1} that are specific to the NW architecture are also detected in resonant Raman spectra and are attributed to defect-activated scattering involving zone-edge transverse optical phonons and surface optical phonons, respectively. It is concluded that the formation of the involved defect states are mainly promoted during the NW growth with a high V/III ratio.

  17. Room temperature spin transport in undoped (110) GaAs/AlGaAs quantum wells

    SciTech Connect (OSTI)

    Yokota, Nobuhide Aoshima, Yohei; Ikeda, Kazuhiro; Kawaguchi, Hitoshi

    2014-02-17

    We are reporting on our first observation of a micrometer-order electron spin transport in a (110) GaAs/AlGaAs multiple quantum well (QW) at room temperature using a space- and time-resolved Kerr rotation technique. A 37-μm transport was observed within an electron spin lifetime of 1.2 ns at room temperature when using an in-plane electric field of 1.75 kV/cm. The spatio-temporal profiles of electron spins were well reproduced by the spin drift-diffusion equations coupled with the Poisson equation, supporting the validity of the measurement. The results suggest that (110) QWs are useful as a spin transport layer for semiconductor spintronic devices operating at room temperature.

  18. Large linear magnetoresistance in a GaAs/AlGaAs heterostructure

    SciTech Connect (OSTI)

    Aamir, Mohammed Ali Goswami, Srijit Ghosh, Arindam; Baenninger, Matthias; Farrer, Ian; Ritchie, David A.; Tripathi, Vikram; Pepper, Michael

    2013-12-04

    We report non-saturating linear magnetoresistance (MR) in a two-dimensional electron system (2DES) at a GaAs/AlGaAs heterointerface in the strongly insulating regime. We achieve this by driving the gate voltage below the pinch-off point of the device and operating it in the non-equilibrium regime with high source-drain bias. Remarkably, the magnitude of MR is as large as 500% per Tesla with respect to resistance at zero magnetic field, thus dwarfing most non-magnetic materials which exhibit this linearity. Its primary advantage over most other materials is that both linearity and the enormous magnitude are retained over a broad temperature range (0.3 K to 10 K), thus making it an attractive candidate for cryogenic sensor applications.

  19. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    SciTech Connect (OSTI)

    Wagener, M. C.; Botha, J. R.; Carrington, P. J.; Krier, A.

    2014-07-28

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  20. Sidewall passivation for InGaN/GaN nanopillar light emitting diodes

    SciTech Connect (OSTI)

    Choi, Won Hyuck; Abraham, Michael; Yu, Shih-Ying [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); You, Guanjun; Liu, Jie; Wang, Li; Xu, Jian, E-mail: jianxu@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mohney, Suzanne E., E-mail: mohney@ems.psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-07-07

    We studied the effect of sidewall passivation on InGaN/GaN multiquantum well-based nanopillar light emitting diode (LED) performance. In this research, the effects of varying etch rate, KOH treatment, and sulfur passivation were studied for reducing nanopillar sidewall damage and improving device efficiency. Nanopillars prepared under optimal etching conditions showed higher photoluminescence intensity compared with starting planar epilayers. Furthermore, nanopillar LEDs with and without sulfur passivation were compared through electrical and optical characterization. Suppressed leakage current under reverse bias and four times higher electroluminescence (EL) intensity were observed for passivated nanopillar LEDs compared with unpassivated nanopillar LEDs. The suppressed leakage current and EL intensity enhancement reflect the reduction of non-radiative recombination at the nanopillar sidewalls. In addition, the effect of sulfur passivation was found to be very stable, and further insight into its mechanism was gained through transmission electron microscopy.

  1. Ultrafast dynamics of type-II GaSb/GaAs quantum dots

    SciTech Connect (OSTI)

    Komolibus, K.; Piwonski, T.; Gradkowski, K.; Reyner, C. J.; Liang, B.; Huffaker, D. L.; Huyet, G.; Houlihan, J.

    2015-01-19

    In this paper, room temperature two-colour pump-probe spectroscopy is employed to study ultrafast carrier dynamics in type-II GaSb/GaAs quantum dots. Our results demonstrate a strong dependency of carrier capture/escape processes on applied reverse bias voltage, probing wavelength and number of injected carriers. The extracted timescales as a function of both forward and reverse bias may provide important information for the design of efficient solar cells and quantum dot memories based on this material. The first few picoseconds of the dynamics reveal a complex behaviour with an interesting feature, which does not appear in devices based on type-I materials, and hence is linked to the unique carrier capture/escape processes possible in type-II structures.

  2. Elastic properties of Pu metal and Pu-Ga alloys

    SciTech Connect (OSTI)

    Soderlind, P; Landa, A; Klepeis, J E; Suzuki, Y; Migliori, A

    2010-01-05

    We present elastic properties, theoretical and experimental, of Pu metal and Pu-Ga ({delta}) alloys together with ab initio equilibrium equation-of-state for these systems. For the theoretical treatment we employ density-functional theory in conjunction with spin-orbit coupling and orbital polarization for the metal and coherent-potential approximation for the alloys. Pu and Pu-Ga alloys are also investigated experimentally using resonant ultrasound spectroscopy. We show that orbital correlations become more important proceeding from {alpha} {yields} {beta} {yields} {gamma} plutonium, thus suggesting increasing f-electron correlation (localization). For the {delta}-Pu-Ga alloys we find a softening with larger Ga content, i.e., atomic volume, bulk modulus, and elastic constants, suggest a weakened chemical bonding with addition of Ga. Our measurements confirm qualitatively the theory but uncertainties remain when comparing the model with experiments.

  3. Germanium subcells for multijunction GaInP/GaInAs/Ge solar cells

    SciTech Connect (OSTI)

    Kalyuzhnyy, N. A.; Gudovskikh, A. S.; Evstropov, V. V.; Lantratov, V. M.; Mintairov, S. A.; Timoshina, N. Kh.; Shvarts, M. Z.; Andreev, V. M.

    2010-11-15

    Photovoltaic converters based on n-GaInP/n-p-Ge heterostructures grown by the OMVPE under different conditions of formation of the p-n junction are studied. The heterostructures are intended for use as narrow-gap subcells of the GaInP/GaInAs/Ge three-junction solar cells. It is shown that, in Ge p-tn junctions, along with the diffusion mechanism, the tunneling mechanism of the current flow exists; therefore, the two-diode electrical equivalent circuit of the Ge p-n junction is used. The diode parameters are determined for both mechanisms from the analysis of both dark and 'light' current-voltage dependences. It is shown that the elimination of the component of the tunneling current allows one to increase the efficiency of the Ge subcell by {approx}1% with conversion of nonconcentrated solar radiation. The influence of the tunneling current on the efficiency of the Ge-based devices can be in practice reduced to zero at photogenerated current density of {approx}1.5 A/cm{sup 2} due to the use of the concentrated solar radiation.

  4. Thermal Design and Characterization of Heterogeneously Integrated InGaP/GaAs HBTs

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

    Choi, Sukwon; Peake, Gregory M.; Keeler, Gordon A.; Geib, Kent M.; Briggs, Ronald D.; Beechem, Thomas E.; Shaffer, Ryan A.; Clevenger, Jascinda; Patrizi, Gary A.; Klem, John F.; et al

    2016-04-21

    Flip-chip heterogeneously integrated n-p-n InGaP/GaAs heterojunction bipolar transistors (HBTs) with integrated thermal management on wide-bandgap AlN substrates followed by GaAs substrate removal are demonstrated. Without thermal management, substrate removal after integration significantly aggravates self-heating effects, causing poor I–V characteristics due to excessive device self-heating. An electrothermal codesign scheme is demonstrated that involves simulation (design), thermal characterization, fabrication, and evaluation. Thermoreflectance thermal imaging, electrical-temperature sensitive parameter-based thermometry, and infrared thermography were utilized to assess the junction temperature rise in HBTs under diverse configurations. In order to reduce the thermal resistance of integrated devices, passive cooling schemes assisted by structural modification, i.e.,more » positioning indium bump heat sinks between the devices and the carrier, were employed. By implementing thermal heat sinks in close proximity to the active region of flip-chip integrated HBTs, the junction-to-baseplate thermal resistance was reduced over a factor of two, as revealed by junction temperature measurements and improvement of electrical performance. In conclusion, the suggested heterogeneous integration method accounts for not only electrical but also thermal requirements providing insight into realization of advanced and robust III–V/Si heterogeneously integrated electronics.« less

  5. Transport properties of InGaAs/GaAs Heterostructures with {delta}-doped quantum wells

    SciTech Connect (OSTI)

    Baidus, N. V.; Vainberg, V. V.; Zvonkov, B. N.; Pylypchuk, A. S. Poroshin, V. N.; Sarbey, O. G.

    2012-05-15

    The lateral transport of electrons in single- and double-well pseudomorphic GaAs/n-InGaAs/GaAs heterostructures with quantum wells 50-100 meV deep and impurity {delta}-layers in the wells, with concentrations in the range 10{sup 11} < N{sub s} < 10{sup 12} cm{sup -2}, has been investigated. Single-well structures with a doped well at the center exhibit a nonmonotonic temperature dependence of the Hall coefficient and an increase in low-temperature electron mobility with an increase in the impurity concentration. The results obtained indicate that the impurity-band electron states play an important role in the conductivity of these structures. Involvement of the impurity band also allows to explain adequately the characteristics of the conductivity of double-well structures; in contrast to single-well structures, band bending caused by asymmetric doping is of great importance. The numerical calculations of conductivity within the model under consideration confirm these suggestions.

  6. Optical properties of multi-stacked InGaAs/GaNAs quantum dot solar cell fabricated on GaAs (311)B substrate

    SciTech Connect (OSTI)

    Shoji, Yasushi; Akimoto, Katsuhiro; Okada, Yoshitaka

    2012-09-15

    Quantum dot solar cells (QDSCs) comprised of 10 stacked pairs of strain-compensated InGaAs/GaNAs QD structure have been fabricated by atomic hydrogen-assisted molecular beam epitaxy. A homogeneous and high-density QD array structure with improved in-plane ordering and total density of {approx}10{sup 12} cm{sup -2} has been achieved on GaAs (311)B grown at 460 Degree-Sign C after stacking. The external quantum efficiency (EQE) of InGaAs/GaNAs QDSC increases in the longer wavelength range due to additive contribution from QD layers inserted in the intrinsic region. The short-circuit current density measured for QDSC is 17.2 mA/cm{sup 2} compared to 14.8 mA/cm{sup 2} of GaAs reference cell. Further, an increase in EQE due to photocurrent production by 2-step photon absorption has been observed at room temperature though it is still small at around 0.1%.

  7. Reactive codoping of GaAlInP compound semiconductors (Patent...

    Office of Scientific and Technical Information (OSTI)

    Patent: Reactive codoping of GaAlInP compound semiconductors Citation Details In-Document Search Title: Reactive codoping of GaAlInP compound semiconductors A GaAlInP compound ...

  8. Growth and Band Offsets of Epitaxial Lanthanide Oxides on GaN...

    Office of Scientific and Technical Information (OSTI)

    M.T.T., 60 (6) (2012) 3 Jon Ihlefeld, Sandia National Laboratories Electronic Materials ... Undoped GaN Undoped AlGaN Doped AlGaN 2D Electron Gas Enhancement Mode (nominally ...

  9. General Atomics (GA) Fusion News: A New Spin on Understanding Plasma

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

    Confinement | Princeton Plasma Physics Lab General Atomics (GA) Fusion News: A New Spin on Understanding Plasma Confinement American Fusion News Category: General Atomics (GA) Link: General Atomics (GA) Fusion News: A New Spin on Understanding Plasma Confinement

  10. Deep porosity preservation in the Norphlet Formation, Mobil Bay, Alabama

    SciTech Connect (OSTI)

    Ajdukiewicz, J.M.; Paxton, S.T.; Szabvo, J.O. )

    1991-03-01

    Compaction and pressure solution have commonly been assumed to destroy primary intergranular porosity in deeply buried sandstones. However, primary porosities of up to 20% are preserved at depths greater than 20,000 feet in the Norphlet Formation of Mobile Bay. Previous workers have called upon a number of mechanisms to preserve these high porosities in the Norphlet, specifically chlorite rim cements, gas emplacement, overpressuring, and decementation. In contrast, our study of data from 23 Norphlet wells, including 450 thin sections, indicates that these suggested mechanisms are not the primary cause of porosity preservation in the Norphlet. The authors propose an alternative interpretation: that in the Norphlet, as in other well-sorted, ductile-grain-poor sandstones, porosity loss from compaction did not go to completion under reservoir (premetamorphic) conditions, but stabilized at depths of about 5,000-8,000 feet and porosity values of about 26%. Porosity loss below these values is due to cementation. For cementation to occur, both an adequate source of cement and geochemical conditions favoring cement precipitation must be present. Computer simulations of Norphlet burial history, including post-depositional fluid-flow patterns, suggest that conditions favorable to quartz cementation never occurred in the bulk of the Norphlet because of the formation's stratigraphic position and isolation from a basinward source of silica-saturated fluids.

  11. HOOPER BAY HOUSING ANALYSIS AND ENERGY FEASIBILITY REPORT

    SciTech Connect (OSTI)

    SEA LION CORPORATION; COLD CLIMATE HOUSING RESEARCH CENTER; SOLUTIONS FOR HEALTHY BREATHING; WHITNEY CONSTRUCTION

    2012-12-30

    Sea Lion applied for and received a grant from the Department of Energy (DOE) towards this end titled “Energy Efficiency Development and Deployment in Indian Country”. The initial objectives of the Hooper Bay Energy Efficiency Feasibility Study were to demonstrate a 30% reduction in residential/commercial energy usage and identify the economic benefits of implementing energy efficiency measures to the Tribe through: (1) partnering with Whitney Construction and Solutions for Healthy Breathing in the training and hire of 2 local energy assessors to conduct energy audits of 9 representative housing models and 2 commercial units in the community. These homes are representative of 52 homes constructed across different eras. (2) partnering with Cold Climate Housing Research Center to document current electrical and heating energy consumption and analyze data for a final feasibility report (3) assessing the economics of electricity & heating fuel usage; (4) projecting energy savings or fossil fuel reduction by modeling of improvement scenarios and cost feasibility The following two objectives will be completed after the publication of this report: (5) the development of materials lists for energy efficiency improvements (6) identifying financing options for the follow-up energy efficiency implementation phase.

  12. Defect reduction in epitaxial GaSb grown on nanopatterned GaAs substrates using full wafer block copolymer lithography

    SciTech Connect (OSTI)

    Jha, Smita; Liu, C.-C.; Nealey, P. F.; Kuech, T. F.; Kuan, T. S.; Babcock, S. E.; Park, J. H.; Mawst, L. J.

    2009-08-10

    Defect reduction in the large lattice mismatched system of GaSb on GaAs, {approx}7%, was accomplished using full wafer block copolymer (BCP) lithography. A self-assembled BCP mask layer was used to generate a hexagonal pattern of {approx}20 nm holes on {approx}40 nm centers in a 20 nm SiO{sub 2} layer. GaSb growth initially takes place selectively within these holes leading to a dense array of small, strain-relaxed epitaxial GaSb islands. The GaSb grown on the patterned SiO{sub 2} layer exhibits a reduction in the x-ray linewidth attributed to a decrease in the threading dislocation density when compared to blanket pseudomorphic film growth.

  13. Structural and emission properties of InGaAs/GaAs quantum dots emitting at 1.3??m

    SciTech Connect (OSTI)

    Goldmann, Elias Jahnke, Frank; Paul, Matthias; Kettler, Jan; Jetter, Michael; Michler, Peter; Krause, Florian F.; Mller, Knut; Mehrtens, Thorsten; Rosenauer, Andreas

    2014-10-13

    A combined experimental and theoretical study of InGaAs/GaAs quantum dots (QDs) emitting at 1.3??m under the influence of a strain-reducing InGaAs quantum well is presented. We demonstrate a red shift of 2040?nm observed in photoluminescence spectra due to the quantum well. The InGaAs/GaAs QDs grown by metal organic vapor phase epitaxy show a bimodal height distribution (1?nm and 5?nm) and indium concentrations up to 90%. The emission properties are explained with combined tight-binding and configuration-interaction calculations of the emission wavelengths in conjunction with high-resolution scanning transmission electron microscopy investigations of QD geometry and indium concentrations in the QDs, which directly enter the calculations. QD geometries and concentration gradients representative for the ensemble are identified.

  14. Progress toward technology transition of GaInP{sub 2}/GaAs/Ge multijunction solar cells

    SciTech Connect (OSTI)

    Keener, D.N.; Marvin, D.C.; Brinker, D.J.; Curtis, H.B.; Price, P.M.

    1997-12-31

    The objective of the joint WL/PL/NASA Multijunction Solar Cell Manufacturing Technology (ManTech) Program is to scale up high efficiency GaInP{sub 2}/GaAs/Ge multijunction solar cells to production size, quantity, and yield while limiting the production cost/Watt ($/W) to 15% over GaAs cells. Progress made by the program contractors, Spectrolab and TECSTAR, include, respectively, best cell efficiencies of 25.76% and 24.7% and establishment of 24.2% and 23.8% lot average efficiency baseline designs. The paper also presents side-by-side testing results collected by Phillips Laboratory and NASA Lewis on Phase 1 deliverable cells, which shows compliance with program objectives. Cell performance, pre- and post-radiation, and temperature coefficient results on initial production GaInP{sub 2}/GaAs/Ge solar cells will be presented.

  15. Time series monitoring of water quality and microalgal diversity in a tropical bay under intense anthropogenic interference (SW coast of the Bay of Bengal, India)

    SciTech Connect (OSTI)

    Shaik, Aziz ur Rahman; Biswas, Haimanti; Reddy, N.P.C.; Srinivasa Rao, V.; Bharathi, M.D.; Subbaiah, Ch.V.

    2015-11-15

    In recent decades, material fluxes to coastal waters from various land based anthropogenic activities have significantly been enhanced around the globe which can considerably impact the coastal water quality and ecosystem health. Hence, there is a critical need to understand the links between anthropogenic activities in watersheds and its health. Kakinada Bay is situated at the SW part of the Bay of Bengal, near to the second largest mangrove cover in India with several fertilizer industries along its bank and could be highly vulnerable to different types of pollutants. However, virtually, no data is available so far reporting its physicochemical status and microalgal diversity at this bay. In order to fill this gap, we conducted three time series observations at a fixed station during January, December and June 2012, at this bay measuring more than 15 physical, chemical and biological parameters in every 3 h over a period of 36 h in both surface (0 m) and subsurface (4.5 m) waters. Our results clearly depict a strong seasonality between three sampling months; however, any abnormal values of nutrients, biological oxygen demand or dissolved oxygen level was not observed. A Skeletonema costatum bloom was observed in December which was probably influenced by low saline, high turbid and high Si input through the river discharge. Otherwise, smaller diatoms like Thalassiosira decipiens, Thalassiothrix frauenfeldii, and Thalassionema nitzschioides dominated the bay. It is likely that the material loading can be high at the point sources due to intense anthropogenic activities, however, gets diluted with biological, chemical and physical processes in the offshore waters. - Highlights: • No signature of enormous nutrient loading was observed over the diel cycle • Dissolved oxygen and BOD concentrations did not show any exceptional trend • Diatoms dominated more than 90% of the total phytoplankton communities • A Skeletonema Costatum (a centric diatom) bloom was

  16. Effect of InGaAs interlayer on the properties of GaAs grown on Si (111) substrate by molecular beam epitaxy

    SciTech Connect (OSTI)

    Wen, Lei; Gao, Fangliang; Li, Jingling; Guan, Yunfang; Wang, Wenliang; Zhou, Shizhong; Lin, Zhiting; Zhang, Xiaona; Zhang, Shuguang E-mail: mssgzhang@scut.edu.cn; Li, Guoqiang E-mail: mssgzhang@scut.edu.cn

    2014-11-21

    High-quality GaAs films have been epitaxially grown on Si (111) substrates by inserting an In{sub x}Ga{sub 1−x}As interlayer with proper In composition by molecular beam epitaxy (MBE). The effect of In{sub x}Ga{sub 1−x}As (0 < x < 0.2) interlayers on the properties of GaAs films grown on Si (111) substrates by MBE has been studied in detailed. Due to the high compressive strain between InGaAs and Si, InGaAs undergoes partial strain relaxation. Unstrained InGaAs has a larger lattice constant than GaAs. Therefore, a thin InGaAs layer with proper In composition may adopt a close lattice constant with that of GaAs, which is beneficial to the growth of high-quality GaAs epilayer on top. It is found that the proper In composition in In{sub x}Ga{sub 1−x}As interlayer of 10% is beneficial to obtaining high-quality GaAs films, which, on the one hand, greatly compensates the misfit stress between GaAs film and Si substrate, and on the other hand, suppresses the formation of multiple twin during the heteroepitaxial growth of GaAs film. However, when the In composition does not reach the proper value (∼10%), the In{sub x}Ga{sub 1−x}As adopts a lower strain relaxation and undergoes a lattice constant smaller than unstrained GaAs, and therefore introduces compressive stress to GaAs grown on top. When In composition exceeds the proper value, the In{sub x}Ga{sub 1−x}As will adopt a higher strain relaxation and undergoes a lattice constant larger than unstrained GaAs, and therefore introduces tensile stress to GaAs grown on top. As a result, In{sub x}Ga{sub 1−x}As interlayers with improper In composition introduces enlarged misfit stress to GaAs epilayers grown on top, and deteriorates the quality of GaAs epilayers. This work demonstrates a simple but effective method to grow high-quality GaAs epilayers and brings up a broad prospect for the application of GaAs-based optoelectronic devices on Si substrates.

  17. Ferromagnetism in undoped One-dimensional GaN Nanowires

    SciTech Connect (OSTI)

    Jeganathan, K. E-mail: jagan@physics.bdu.ac.in; Purushothaman, V.; Debnath, R.; Arumugam, S.

    2014-05-15

    We report an intrinsic ferromagnetism in vertical aligned GaN nanowires (NW) fabricated by molecular beam epitaxy without any external catalyst. The magnetization saturates at ?0.75 emu/gm with the applied field of 3000 Oe for the NWs grown under the low-Gallium flux of 2.4 10{sup ?8} mbar. Despite a drop in saturation magnetization, narrow hysteresis loop remains intact regardless of Gallium flux. Magnetization in vertical standing GaN NWs is consistent with the spectral analysis of low-temperature photoluminescence pertaining to Ga-vacancies associated structural defects at the nanoscale.

  18. Characterization of Zns-GaP Naon-composites

    SciTech Connect (OSTI)

    Todd, V.

    1993-12-09

    It proved possible to produce consistent, high-quality nanocrystalline ZnS powders with grain sizes as small as 8 nm. These powders are nano-porous and are readily impregnated with GaP precursor, although inconsistently. Both crystal structure and small grain size of the ZnS can be maintained through the use of GaP. Heat treatment of the impregnated powders results in a ZnS-GaP composite structure where the grain sizes of the phases are on the order of 10--20 nm. Conventional powder processing should be able to produce optically dense ceramic compacts with improved mechanical properties and suitable IR transmission.

  19. Understanding the Flushing Capability of Bellingham Bay and Its Implication on Bottom Water Hypoxia

    SciTech Connect (OSTI)

    Wang, Taiping; Yang, Zhaoqing

    2015-05-05

    In this study, an unstructured-grid finite-volume coastal ocean model (FVCOM) was used to simulate hydrodynamic circulation and assess the flushing capability in Bellingham Bay, Washington, USA. The model was reasonably calibrated against field observations for water level, velocity and salinity, and was further used to calculate residence time distributions in the study site. The model results suggest that, despite the large tidal ranges (~4 m during spring tide), tidal currents are relatively weak in Bellingham Bay with surface currents generally below 0.5 m/s. The local residence time in Bellingham Bay varies from to near zero to as long as 15 days, depending on the location and river flow condition. In general, Bellingham Bay is a well-flushed coastal embayment affected by freshwater discharge, tides, wind, and density-driven circulation. The basin-wide global residence time ranges from 5-7 days. The model results also provide useful information on possible causes of the emerging summertime hypoxia problem in the north central region of Bellingham Bay. It was concluded that the formation of the bottom hypoxic water should result from the increased consumption rate of oxygen in the bottom oceanic inflow with low dissolved oxygen by organic matters accumulated at the regions characterized with relatively long residence time in summer months.

  20. High Voltage GaN Schottky Rectifiers

    SciTech Connect (OSTI)

    CAO,X.A.; CHO,H.; CHU,S.N.G.; CHUO,C.-C.; CHYI,J.-I.; DANG,G.T.; HAN,JUNG; LEE,C.-M.; PEARTON,S.J.; REN,F.; WILSON,R.G.; ZHANG,A.P.

    1999-10-25

    Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and {ge}15 for the 2kV diodes. Reverse recovery times were <0.2{micro}sec for devices switched from a forward current density of {approx}500A{center_dot}cm{sup -2} to a reverse bias of 100V.

  1. Making it pay in Athens, GA

    SciTech Connect (OSTI)

    Malloy, M.G.

    1997-04-01

    The materials recovery facility (MRF) in Athens, GA, is a well-fed recycling facility. But, if the local government has its way, it will be even better fed in the near future. The Athens-Clarke County (ACC) regional municipality in which the facility resides has a put-or-pay contract with the plant`s owner/operator, under which the more it feeds the MRF, the more money it receives in return, through the sale of recycled end products. The ACC Solid Waste Department uses a volume-based waste collection system that encourages residents to recycle--the more they recycle, the less trash they have to put out, and the less they pay each month. The Athens facility, which will be a featured site tour at next month`s WasteExpo `97 in nearby Atlanta, had its ground-breaking two years ago, in April 1995. ACC is responsible for delivering material--or seeing that recyclables are delivered--to the MRF, which is owned and operated by Resource Recovery Systems (RRS, Centerbrook, Conn.). Over the past year, ACC has stepped up various incentives for businesses to recycle and send their recyclables to the facility, including instituting pilot programs for commercial interests that offer them versions of volume-based collection similar to that done by residents.

  2. Outdoor Testing of GaInP2/GaAs Tandem Cells with Top Cell Thickness Varied

    SciTech Connect (OSTI)

    McMahon, W. E.; Emergy, K. E.; Friedman, D. J.; Ottoson, L.; Young, M. S.; Ward, J. S.; Kramer, C. M.; Duda, A.; Kurtz, S.

    2005-08-01

    In this study, we measure the performance of GaInP2/GaAs tandem cells under direct beam sunlight outdoors in order to quantify their sensitivity to both spectral variation and GaInP2 top-cell thickness. A set of cells with five different top-cell thicknesses was mounted on a two-axis tracker with the incident sunlight collimated to exclude all except the direct beam. Current-voltage (I-V) curves were taken throughout the course of several days, along with measurements of the direct solar spectrum. Our two major conclusions are: (1) GaInP2/GaAs tandem cells designed for either the ASTM G-173 direct (G-173D) spectrum or the "air mass 1.5 global" (AM1.5G) spectrum perform the best, and (2) cells can be characterized indoors and modeled using outdoor spectra with the same result. These results are equally valid for GaInP2/GaAs/Ge triple-junction cells.

  3. Local Structures and Interface Morphology of InGaAsN Thin Films Grown on GaAs

    SciTech Connect (OSTI)

    Allerman, A.A.; Chen, J.G.; Geisz, J.F.; Huang, S.; Hulbert, S.L.; Jones, E.D.; Kao, Y.H.; Kurtz, S.; Kurtz, S.R.; Olson, J.M.; Soo, Y.L.

    1999-02-23

    The compound semiconductor system InGaAsN exhibits many intriguing properties which are particularly useful for the development of innovative high efficiency thin film solar cells and long wavelength lasers. The bandgap in these semiconductors can be varied by controlling the content of N and In and the thin films can yet be lattice-matched to GaAs. In the present work, x-ray absorption fine structure (XAFS) and grazing incidence x-ray scattering (GIXS) techniques have been employed to probe the local environment surrounding both N and In atoms as well as the interface morphology of InGaAsN thin films epitaxially grown on GaAs. The soft x-ray XAFS results around nitrogen K-edge reveal that N is in the sp{sup 3} hybridized bonding configuration in InGaAsN and GaAsN, suggesting that N impurities most likely substitute for As sites in these two compounds. The results of In K-edge XAFS suggest a possible trend of a slightly larger coordination number of As nearest neighbors around In atoms in InGaAsN samples with a narrower bandgap whereas the In-As interatomic distance remains practically the same as in InAs within the experimental uncertainties. These results combined suggest that N-substitution of the As sites plays an important role of bandgap-narrowing while in the meantime counteracting the compressive strain caused by In-doping. Grazing incidence x-ray scattering (GIXS) experiments verify that InGaAsN thin films can indeed form very smooth interfaces with GaAs yielding an average interfacial roughness of 5-20{angstrom}.

  4. Electrical spin injection using GaCrN in a GaN based spin light emitting diode

    SciTech Connect (OSTI)

    Banerjee, D.; Ganguly, S.; Saha, D.; Adari, R.; Sankaranarayan, S.; Kumar, A.; Aldhaheri, R. W.; Hussain, M. A.; Balamesh, A. S.

    2013-12-09

    We have demonstrated electrical spin-injection from GaCrN dilute magnetic semiconductor (DMS) in a GaN-based spin light emitting diode (spin-LED). The remanent in-plane magnetization of the thin-film semiconducting ferromagnet has been used for introducing the spin polarized electrons into the non-magnetic InGaN quantum well. The output circular polarization obtained from the spin-LED closely follows the normalized in-plane magnetization curve of the DMS. A saturation circular polarization of ?2.5% is obtained at 200?K.

  5. Microscopic, electrical and optical studies on InGaN/GaN quantum wells based LED devices

    SciTech Connect (OSTI)

    Mutta, Geeta Rani; Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna

    2014-02-21

    We report here on the micro structural, electronic and optical properties of a GaN-based InGaN/GaN MQW LED grown by the MOVPE method. The present study shows that the threading dislocations present in these LED structures are terminated as V pits at the surface and have an impact on the electrical and optical activity of these devices. It has been pointed that these dislocations were of edge, screw and mixed types. EBIC maps suggest that the electrically active defects are screw and mixed dislocations and behave as nonradiative recombinant centres.

  6. Effects of light illumination on electron velocity of AlGaN/GaN heterostructures under high electric field

    SciTech Connect (OSTI)

    Guo, Lei; Yang, Xuelin Cheng, Jianpeng; Sang, Ling; Xu, Fujun; Tang, Ning; Feng, Zhihong; Lv, Yuanjie; Wang, Xinqiang; Shen, B.; Ge, Weikun

    2014-12-15

    We have investigated the variation of electron velocity in AlGaN/GaN heterostructures depending on illuminating light intensity and wavelength. It is shown that the electron velocity at high electric field increases under above-band light illumination. This electron velocity enhancement is found to be related to the photo-generated cold holes which interact with hot electrons and thus accelerate the energy relaxation at high electric field. The results suggest an alternative way to improve the electron energy relaxation rate and hence the electron velocity in GaN based heterostructures.

  7. High-power InGaAs/GaAs quantum-well laser with enhanced broad spectrum of stimulated emission

    SciTech Connect (OSTI)

    Wang, Huolei; Yu, Hongyan; Zhou, Xuliang; Kan, Qiang; Yuan, Lijun; Wang, Wei; Pan, Jiaoqing; Chen, Weixi; Ding, Ying

    2014-10-06

    We report the demonstration of an InGaAs/GaAs quantum well (QW) broadband stimulated emission laser with a structure that integrated a GaAs tunnel junction with two QW active regions. The laser exhibits ultrabroad lasing spectral coverage of ?51?nm at a center wavelength of 1060?nm with a total emission power of 790 mW, corresponding to a high average spectral power density of 15.5 mW/nm, under pulsed current conditions. Compared to traditional lasers, this laser with an asymmetric separate-confinement heterostructure shows broader lasing bandwidth and higher spectral power density.

  8. EA-1992: Funding for Principle Power, Inc., for the WindFloat Pacific Offshore Wind Demonstration Project, offshore of Coos Bay, Oregon

    Broader source: Energy.gov [DOE]

    Funding for Principle Power, Inc., for the WindFloat Pacific Offshore Wind Demonstration Project, offshore of Coos Bay, Oregon

  9. Elba Island, GA Liquefied Natural Gas Imports from Qatar (Million...

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

    Liquefied Natural Gas Imports from Qatar (Million Cubic Feet) Elba Island, GA Liquefied Natural Gas Imports from Qatar (Million Cubic Feet) Year Jan Feb Mar Apr May Jun Jul Aug Sep...

  10. Elba Island, GA Natural Gas Liquefied Natural Gas Imports from...

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

    Egypt (Million Cubic Feet) Elba Island, GA Natural Gas Liquefied Natural Gas Imports from Egypt (Million Cubic Feet) Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2011 5,780 ...

  11. Linear and nonlinear optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell spherical quantum dot

    SciTech Connect (OSTI)

    Emre Kavruk, Ahmet E-mail: aekavruk@gmail.com; Koc, Fatih; Sahin, Mehmet E-mail: mehsahin@gmail.com

    2013-11-14

    In this work, the optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell quantum dot heterostructure have been studied as a function of Al doping concentrations for cases with and without a hydrogenic donor atom. It has been observed that the absorption coefficient strength and/or resonant absorption wavelength can be adjusted by changing the Al content of inner-barrier and/or outer-barrier regions. Besides, it has been shown that the donor atom has an important effect on the control of the electronic and optical properties of the structure. The results have been presented as a function of the Al contents of the inner-barrier x and outer-barrier y regions and probable physical reasons have been discussed.

  12. Evaporation-based Ge/.sup.68 Ga Separation

    DOE Patents [OSTI]

    Mirzadeh, Saed; Whipple, Richard E.; Grant, Patrick M.; O'Brien, Jr., Harold A.

    1981-01-01

    Micro concentrations of .sup.68 Ga in secular equilibrium with .sup.68 Ge in strong aqueous HCl solution may readily be separated in ionic form from the .sup.68 Ge for biomedical use by evaporating the solution to dryness and then leaching the .sup.68 Ga from the container walls with dilute aqueous solutions of HCl or NaCl. The chloro-germanide produced during the evaporation may be quantitatively recovered to be used again as a source of .sup.68 Ga. If the solution is distilled to remove any oxidizing agents which may be present as impurities, the separation factor may easily exceed 10.sup.5. The separation is easily completed and the .sup.68 Ga made available in ionic form in 30 minutes or less.

  13. High Quantum Efficiency AlGaN/InGaN Photodetectors

    SciTech Connect (OSTI)

    Buckley, James H; Leopold, Daniel

    2009-11-24

    High efficiency photon counting detectors in use today for high energy particle detection applications have a significant spectral mismatch with typical sources and have a number of practical problems compared with conventional bialkali photomultiplier tubes. Numerous high energy physics experiments that employ scintillation light detectors or Cherenkov detectors would benefit greatly from photomultipliers with higher quantum efficiencies. The need for extending the sensitivity of photon detectors to the blue and UV wavebands comes from the fact that both Cherenkov light and some scintillators have an emission spectrum which is peaked at short wavelengths. This research involves the development of high quantum efficiency, high gain, UV/blue photon counting detectors based on AlGaN/InGaN photocathode heterostructures grown by molecular beam epitaxy (MBE). The work could eventually lead to nearly ideal light detectors with a number of distinct advantages over existing technologies for numerous applications in high-energy physics and particle astrophysics. Potential advantages include much lower noise detection, better stability and radiation resistance than other cathode structures, very low radioactive background levels for deep underground experiments and high detection efficiency of individual UV-visible photons. We are also working on the development of photocathodes with intrinsic gain, initially improving the detection efficiency of hybrid semiconductor-vacuum tube devices, and eventually leading to an all-solid-state photomultiplier device.

  14. Enhanced optical property in quaternary GaInAsSb/AlGaAsSb quantum wells

    SciTech Connect (OSTI)

    Lin, Chien-Hung Lee, Chien-Ping

    2014-10-21

    High quality GaInAsSb/AlGaAsSb quantum wells (QWs) have been grown by molecular beam epitaxy using proper interface treatments. By controlling the group-V elements at interfaces, we obtained excellent optical quality QWs, which were free from undesired localized trap states, which may otherwise severely affect the exciton recombination. Strong and highly efficient exciton emissions up to room temperature with a wavelength of 2.2 μm were observed. A comprehensive investigation on the QW quality was carried out using temperature dependent and power dependent photoluminescence (PL) measurements. The PL emission intensity remains nearly constant at low temperatures and is free from the PL quenching from the defect induced localized states. The temperature dependent emission energy had a bulk-like behavior, indicating high quality well/barrier interfaces. Because of the uniformity of the QWs and smooth interfaces, the low temperature limit of inhomogeneous line width broadening is as small as 5 meV.

  15. Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii: Assessment and Recommendations

    SciTech Connect (OSTI)

    Burman, K.; Kandt, A.; Lisell, L.; Booth, S.; Walker, A.; Roberts, J.; Falcey, J.

    2011-11-01

    DOD's U.S. Pacific Command has partnered with the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) to assess opportunities for increasing energy security through renewable energy and energy efficiency in Hawaii installations. NREL selected Marine Corps Base Hawaii (MCBH), Kaneohe Bay to receive technical support for net zero energy assessment and planning funded through the Hawaii Clean Energy Initiative (HCEI). NREL performed a comprehensive assessment to appraise the potential of MCBH Kaneohe Bay to achieve net zero energy status through energy efficiency, renewable energy, and electric vehicle integration. This report summarizes the results of the assessment and provides energy recommendations.

  16. 9 Cool Technologies at the Bay Area Maker Faire | Department of Energy

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

    9 Cool Technologies at the Bay Area Maker Faire 9 Cool Technologies at the Bay Area Maker Faire May 12, 2016 - 10:14am Addthis PARTS FROM THE WORLD’S LARGEST LASER 1 of 9 PARTS FROM THE WORLD'S LARGEST LASER You're looking at the inside of the world's largest and most powerful laser. It focuses the intense energy of 192 giant laser beams on a BB-sized target in experiments to create nuclear fusion. Examples of the optics that focus the lasers and targets at which they're aimed will be on

  17. Mismatch relaxation by stacking fault formation of AlN islands in AlGaN/GaN structures on m-plane GaN substrates

    SciTech Connect (OSTI)

    Smalc-Koziorowska, Julita; Sawicka, Marta; Skierbiszewski, Czeslaw; Grzegory, Izabella

    2011-08-08

    We study the mismatch relaxation of 2-5 nm thin elongated AlN islands formed during growth of AlGaN on bulk m-plane GaN by molecular beam epitaxy. The relaxation of these m-plane AlN layers is anisotropic and occurs through the introduction of stacking faults in [0001] planes during island coalescence, while no relaxation is observed along the perpendicular [1120] direction. This anisotropy in the mismatch relaxation and the formation of stacking faults in the AlN islands are explained by the growth mode of the AlN platelets and their coalescence along the [0001] direction.

  18. A new InGaP/GaAs tunneling heterostructure-emitter bipolar transistor (T-HEBT)

    SciTech Connect (OSTI)

    Tsai, Jung-Hui; Lee, Ching-Sung; Lour, Wen-Shiung; Ma, Yung-Chun; Ye, Sheng-Shiun

    2011-05-15

    Excellent characteristics of an InGaP/GaAs tunneling heterostructure-emitter bipolar transistor (T-HEBT) are first demonstrated. The insertion of a thin n-GaAs emitter layer between tynneling confinement and base layers effectivelty eliminates the potential spike at base-emitter junction and reduces the collector-emitter offset voltage, while the thin InGaP tunneling confinement layer is employed to reduce the transporting time across emitter region for electrons and maintain the good confinement effect for holes. Experimentally, the studied T-HEBN exhibits a maximum current gain of 285, a relatively low offset voltage of 40 mW, and a current-gain cutoff frequency of 26.4 GHz.

  19. Characterization of Cu(In,Ga)Se2 (CIGS) films with varying gallium ratios

    SciTech Connect (OSTI)

    Claypoole, Jesse; Peace, Bernadette; Sun, Neville; Dwyer, Dan; Eisaman, Matthew D.; Haldar, Pradeep; Efstathiadis, Harry

    2015-09-05

    Cu(In1-x,Gax)Se2 (CIGS) absorber layers were deposited on molybdenum (Mo) coated soda-lime glass substrates with varying Ga content (described as Ga/(In+Ga) ratios) with respect to depth. As the responsible mechanisms for the limitation of the performance of the CIGS solar cells with high Ga contents are not well understood, the goal of this work was to investigate different properties of CIGS absorber films with Ga/(In+Ga) ratios varied between 0.29 and 0.41 (as determined by X-ray florescence spectroscopy (XRF)) in order to better understand the role that the Ga content has on film quality. The Ga grading in the CIGS layer has the effect causing a higher bandgap toward the surface and Mo contact while the band gap in the middle of the CIGS layer is lower. Also, a wider and larger Ga/(In+Ga) grading dip located deeper in the CIGS absorber layers tend to produce larger grains in the regions of the films that have lower Ga/(In+Ga) ratios. It was found that surface roughness decreases from 51.2 nm to 41.0 nm with increasing Ga/(In+Ga) ratios. However, the surface roughness generally decreases if the Ga grading occurs deeper in the absorber layer.

  20. Quaternary AlInGaN/InGaN quantum well on vicinal c-plane substrate for high emission intensity of green wavelengths

    SciTech Connect (OSTI)

    Park, Seoung-Hwan; Pak, Y. Eugene; Park, Chang Young; Mishra, Dhaneshwar; Yoo, Seung-Hyun; Cho, Yong-Hee Shim, Mun-Bo; Kim, Sungjin

    2015-05-14

    Electronic and optical properties of non-trivial semipolar AlInGaN/InGaN quantum well (QW) structures are investigated by using the multiband effective-mass theory and non-Markovian optical model. On vicinal c-plane GaN substrate miscut by a small angle (??GaN/InGaN system is shown to have ?3 times larger spontaneous emission peak intensity than the conventional InGaN/GaN system at green wavelength. It is attributed to much larger optical matrix element of the quaternary AlInGaN/InGaN system, derived from the reduction of internal electric field induced by polarizations. This effect exceeds the performance-degrading factor of smaller quasi-Fermi-level separation for the quaternary AlInGaN/InGaN system than that for the conventional InGaN/GaN system. Results indicate that the use of quaternary III-nitride QWs on vicinal substrates may be beneficial in improving the performance of optical devices emitting green light.

  1. The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

    SciTech Connect (OSTI)

    zduran, Mustafa; Turgut, Kemal; Arikan, Nihat; ?yigr, Ahmet; Candan, Abdullah

    2014-10-06

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.

  2. Efficient carrier relaxation and fast carrier recombination of N-polar InGaN/GaN light emitting diodes

    SciTech Connect (OSTI)

    Feng, Shih-Wei Liao, Po-Hsun; Leung, Benjamin; Han, Jung; Yang, Fann-Wei; Wang, Hsiang-Chen

    2015-07-28

    Based on quantum efficiency and time-resolved electroluminescence measurements, the effects of carrier localization and quantum-confined Stark effect (QCSE) on carrier transport and recombination dynamics of Ga- and N-polar InGaN/GaN light-emitting diodes (LEDs) are reported. The N-polar LED exhibits shorter ns-scale response, rising, delay, and recombination times than the Ga-polar one does. Stronger carrier localization and the combined effects of suppressed QCSE and electric field and lower potential barrier acting upon the forward bias in an N-polar LED provide the advantages of more efficient carrier relaxation and faster carrier recombination. By optimizing growth conditions to enhance the radiative recombination, the advantages of more efficient carrier relaxation and faster carrier recombination in a competitive performance N-polar LED can be realized for applications of high-speed flash LEDs. The research results provide important information for carrier transport and recombination dynamics of an N-polar InGaN/GaN LED.

  3. Effects of high-temperature AIN buffer on the microstructure of AlGaN/GaN HEMTs

    SciTech Connect (OSTI)

    Coerekci, S.; Oeztuerk, M. K.; Yu, Hongbo; Cakmak, M.; Oezcelik, S.; Oezbay, E.

    2013-06-15

    Effects on AlGaN/GaN high-electron-mobility transistor structure of a high-temperature AlN buffer on sapphire substrate have been studied by high-resolution x-ray diffraction and atomic force microscopy techniques. The buffer improves the microstructural quality of GaN epilayer and reduces approximately one order of magnitude the edge-type threading dislocation density. As expected, the buffer also leads an atomically flat surface with a low root-mean-square of 0.25 nm and a step termination density in the range of 10{sup 8} cm{sup -2}. Due to the high-temperature buffer layer, no change on the strain character of the GaN and AlGaN epitaxial layers has been observed. Both epilayers exhibit compressive strain in parallel to the growth direction and tensile strain in perpendicular to the growth direction. However, an high-temperature AlN buffer layer on sapphire substrate in the HEMT structure reduces the tensile stress in the AlGaN layer.

  4. p-doping-free InGaN/GaN light-emitting diode driven by three-dimensional hole gas

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Tiam Tan, Swee; Kyaw, Zabu; Liu, Wei; Ji, Yun; Ju, Zhengang; Zhang, Xueliang [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore) [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Wei Sun, Xiao, E-mail: EXWSUN@ntu.edu.sg [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electronics and Electrical Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Volkan Demir, Hilmi, E-mail: VOLKAN@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electrical and Electronics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey); Department of Physics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey)

    2013-12-23

    Here, GaN/Al{sub x}Ga{sub 1-x}N heterostructures with a graded AlN composition, completely lacking external p-doping, are designed and grown using metal-organic-chemical-vapour deposition (MOCVD) system to realize three-dimensional hole gas (3DHG). The existence of the 3DHG is confirmed by capacitance-voltage measurements. Based on this design, a p-doping-free InGaN/GaN light-emitting diode (LED) driven by the 3DHG is proposed and grown using MOCVD. The electroluminescence, which is attributed to the radiative recombination of injected electrons and holes in InGaN/GaN quantum wells, is observed from the fabricated p-doping-free devices. These results suggest that the 3DHG can be an alternative hole source for InGaN/GaN LEDs besides common Mg dopants.

  5. Evaluation Project 4492

    National Nuclear Security Administration (NNSA)

    Sandia National LaboratoriesNew Mexico (SNLNM) proposes to design, test, and install security system upgrades, at the Kings Bay, Georgia, and Bangor, Washington, Naval Submarine ...

  6. Aleutians East Borough, Alaska: Energy Resources | Open Energy...

    Open Energy Info (EERE)

    in Aleutians East Borough, Alaska Akutan, Alaska Cold Bay, Alaska False Pass, Alaska King Cove, Alaska Nelson Lagoon, Alaska Sand Point, Alaska Retrieved from "http:...

  7. 1,"Salt River Proj Ag I & P Dist",16572,1999,"Coronado","Silver King",525,"1,3",180,0,"ACSR 2156",1

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

    DESTFROM","DESTTO","VOLTAGE","STRUCTYPE","LINEDESIG","LINEOTH","MATERIAL","CIRCUITS" 1,"Salt River Proj Ag I & P Dist",16572,1999,"Coronado","Silver King",525,"1,3",180,0,"ACSR 2156",1 2,"Salt River Proj Ag I & P Dist",16572,1999,"Cholla","Coronado",525,"1,3",73,0,"ACSR 2156",1 3,"Salt River Proj Ag I & P

  8. Intermixing of InGaAs/GaAs Quantum Well Using Multiple Cycles Annealing Cu-doped SiO2

    SciTech Connect (OSTI)

    Hongpinyo, V; Ding, Y H; Dimas, C E; Wang, Y; Ooi, B S; Qiu, W; Goddard, L L; Behymer, E M; Cole, G D; Bond, T C

    2008-06-11

    The authors investigate the effect of intermixing in InGaAs/GaAs quantum well structure using Cu-doped SiO{sub 2}. The incorporation of Cu into the silica film yields larger bandgap shift than typical impurity-free vacancy diffusion (IFVD) method at a lower activation temperature. We also observe enhancement of the photoluminescence (PL) signal from the intermixed InGaAs/GaAs quantum well structure after being cycle-annealed at 850 C.

  9. Characterization of Cu(In,Ga)Se2 (CIGS) films with varying gallium ratios

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

    Claypoole, Jesse; Peace, Bernadette; Sun, Neville; Dwyer, Dan; Eisaman, Matthew D.; Haldar, Pradeep; Efstathiadis, Harry

    2015-09-05

    Cu(In1-x,Gax)Se2 (CIGS) absorber layers were deposited on molybdenum (Mo) coated soda-lime glass substrates with varying Ga content (described as Ga/(In+Ga) ratios) with respect to depth. As the responsible mechanisms for the limitation of the performance of the CIGS solar cells with high Ga contents are not well understood, the goal of this work was to investigate different properties of CIGS absorber films with Ga/(In+Ga) ratios varied between 0.29 and 0.41 (as determined by X-ray florescence spectroscopy (XRF)) in order to better understand the role that the Ga content has on film quality. The Ga grading in the CIGS layer hasmore » the effect causing a higher bandgap toward the surface and Mo contact while the band gap in the middle of the CIGS layer is lower. Also, a wider and larger Ga/(In+Ga) grading dip located deeper in the CIGS absorber layers tend to produce larger grains in the regions of the films that have lower Ga/(In+Ga) ratios. It was found that surface roughness decreases from 51.2 nm to 41.0 nm with increasing Ga/(In+Ga) ratios. However, the surface roughness generally decreases if the Ga grading occurs deeper in the absorber layer.« less

  10. Radiation damage of GaAs thin-film solar cells on Si substrates

    SciTech Connect (OSTI)

    Itoh, Y.; Yamaguchi, M.; Nishioka, T.; Yamamoto, A.

    1987-01-15

    1-MeV electron irradiation damages in GaAs thin-film solar cells on Si substrates are examined for the first time. Damage constant for minority-carrier diffusion length in GaAs heteroepitaxial films on Si substrates is found to be the same as that in GaAs homoepitaxial films on GaAs substrates. This agreement suggests that GaAs/Si has the same defect introduction rate with radiation as GaAs/GaAs. The degradation of GaAs solar cells on Si with electron irradiation is less than that of GaAs solar cells on GaAs, because in the present, GaAs films on Si substrates have lower minority-carrier diffusion length compared to GaAs films on GaAs and these films are insensitive to radiation. The p/sup +/-p/sup +/-n AlGaAs-GaAs heteroface solar cell with junction depth of about 0.3 ..mu..m is concluded to be useful for a high-efficiency and radiation-resistant solar cell fabricated on a Si substrate.

  11. Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence

    SciTech Connect (OSTI)

    Pozina, Galia; Ciechonski, Rafal; Bi, Zhaoxia; Samuelson, Lars; Monemar, Bo

    2015-12-21

    Today's energy saving solutions for general illumination rely on efficient white light emitting diodes (LEDs). However, the output efficiency droop experienced in InGaN based LEDs with increasing current injection is a serious limitation factor for future development of bright white LEDs. We show using cathodoluminescence (CL) spatial mapping at different electron beam currents that threading dislocations are active as nonradiative recombination centers only at high injection conditions. At low current, the dislocations are inactive in carrier recombination due to local potentials, but these potentials are screened by carriers at higher injection levels. In CL images, this corresponds to the increase of the dark contrast around dislocations with the injection (excitation) density and can be linked with droop related to the threading dislocations. Our data indicate that reduction of droop in the future efficient white LED can be achieved via a drastic reduction of the dislocation density by using, for example, bulk native substrates.

  12. Radiation resistance of GaAs-GaAlAs vertical cavity surface emitting lasers

    SciTech Connect (OSTI)

    Jabbour, J.; Zazoui, M.; Sun, G.C.; Bourgoin, J.C.; Gilard, O.

    2005-02-15

    The variations of the optical and electrical characteristics of a vertical cavity surface emitting laser based on GaAs quantum wells have been monitored versus irradiation with 1 MeV electrons. The results are understood by the introduction of nonradiative recombination centers in the wells whose characteristics, capture cross section for minority carriers times their introduction rate, can be determined. A similar study performed for proton irradiation shows that the results can be explained in the same way when the introduction rate of the defects is replaced by the proton energy loss into atomic collisions. These results allow us to deduce the equivalence between electron and proton irradiations: A flux of 1 proton cm{sup -2} which loses an energy E{sub nl} (eV) into atomic collisions is equivalent to a fluence of about 9x10{sup -2} E{sub nl} cm{sup -2}, 1 MeV electrons.

  13. EIS-0296: South Oregon Coast Reinforcement Project, Coos Bay/North Bend, Oregon

    Broader source: Energy.gov [DOE]

    Bonneville Power Administration proposes to build a 500- kilovolt (kV) transmission line and new substation to reinforce electrical service to the southern coast of the state of Oregon. Nucor Steel, a division of Nucor Corporation, may build a new steel mill in the Coos Bay/North Bend, Oregon, area.

  14. EIS-0296: South Oregon Coast Reinforcement Project, Coos Bay/North Bend, Oregon

    Broader source: Energy.gov [DOE]

    This EIS analyzes BPA's proposed action to build a 500- kilovolt (kV) transmission line and new substation to reinforce electrical service to the southern coast of the state of Oregon. Nucor Steel, a division of Nucor Corporation, may build a new steel mill in the Coos Bay/North Bend, Oregon, area.

  15. Systems Performance Analyses of Alaska Wind-Diesel Projects; Toksook Bay, Alaska (Fact Sheet)

    SciTech Connect (OSTI)

    Baring-Gould, I.

    2009-04-01

    This fact sheet summarizes a systems performance analysis of the wind-diesel project in Toksook Bay, Alaska. Data provided for this project include community load data, average wind turbine output, average diesel plant output, thermal load data, average net capacity factor, optimal net capacity factor based on Alaska Energy Authority wind data, average net wind penetration, estimated fuel savings, and wind system availability.

  16. Laser Gain and Threshold Properties in Compressive-Strained and Lattice-Matched GaInNAs/GaAs Quantum Wells

    SciTech Connect (OSTI)

    Chow, W.W.; Jones, E.D.; Modine, N.A.; Allerman, A.A.; Kurtz, S.R.

    1999-08-04

    The optical gain spectra for compressive-strained and lattice-matched GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of lasing threshold current density for different GAInNAs/GaAs laser structures.

  17. Energy Efficiency Feasibility Study and Resulting Plan for the Bay Mills Indian Community

    SciTech Connect (OSTI)

    Kushman, Chris

    2014-02-03

    In 2011 the Inter-Tribal Council of Michigan, Inc. was awarded an Energy Efficiency Development and Deployment in Indian Country grant from the U.S. Department of Energy’s Tribal Energy Program. This grant aimed to study select Bay Mills Indian Community community/government buildings to determine what is required to reduce each building’s energy consumption by 30%. The Bay Mills Indian Community (BMIC) buildings with the largest expected energy use were selected for this study and included the Bay Mills Ellen Marshall Health Center building, Bay Mills Indian Community Administration Building, Bay Mills Community College main campus, Bay Mills Charter School and the Waishkey Community Center buildings. These five sites are the largest energy consuming Community buildings and comprised the study area of this project titled “Energy Efficiency Feasibility Study and Resulting Plan for the Bay Mills Indian Community”. The end objective of this study, plan and the Tribe is to reduce the energy consumption at the Community’s most energy intensive buildings that will, in turn, reduce emissions at the source of energy production, reduce energy expenditures, create long lasting energy conscious practices and positively affect the quality of the natural environment. This project’s feasibility study and resulting plan is intended to act as a guide to the Community’s first step towards planned energy management within its buildings/facilities. It aims to reduce energy consumption by 30% or greater within the subject facilities with an emphasis on energy conservation and efficiency. The energy audits and related power consumption analyses conducted for this study revealed numerous significant energy conservation and efficiency opportunities for all of the subject sites/buildings. In addition, many of the energy conservation measures require no cost and serve to help balance other measures requiring capital investment. Reoccurring deficiencies relating to heating

  18. Vertical zone melt growth of GaAs

    SciTech Connect (OSTI)

    Henry, R.L.; Nordquist, P.E.R.; Gorman, R.J.

    1993-12-31

    A Vertical Zone Melt (VZM) technique has been applied to the single crystal growth of GaAs. A pyrolytic boron nitride crucible and a (100) oriented seed were used along with liquid encapsulation by boric oxide. In the case of GaAs, the ampoule was pressurized with either argon or argensic vapor from elemental arsenic at pressures ranging from 1 to 2 atmospheres. A molten zone length of 22 mm gave a growth interface which is nearly flat and resulted in routine single crystal growth. Temperature gradients of 4{degrees}C/cm. and 9{degrees}C/cm. have produced dislocation densities of <1000/cm{sup 2} and 2000-5000/cm{sup 2} respectively for 34 mm diameter crystals of GaAs. Post growth cooling rates for GaAs have been 35, 160 and 500{degrees}C/hr. The cooling rate has been found to affect the number and size of arsenic precipitates and the EL2 concentration in the GaAs crystal. The effects of these and other growth parameters on the crystalline perfection and electrical properties of the crystals will be discussed.

  19. Targeting Net Zero Energy at Marine Corps Base Hawaii, Kaneohe Bay: Preprint

    SciTech Connect (OSTI)

    Burman, K.; Kandt, A.; Lisell, L.; Booth, S.

    2012-05-01

    This paper summarizes the results of an NREL assessment of Marine Corps Base Hawaii (MCBH), Kaneohe Bay to appraise the potential of achieving net zero energy status through energy efficiency, renewable energy, and hydrogen vehicle integration. In 2008, the U.S. Department of Defense's U.S. Pacific Command partnered with the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) to assess opportunities for increasing energy security through renewable energy and energy efficiency at Hawaii military installations. DOE selected Marine Corps Base Hawaii (MCBH), Kaneohe Bay, to receive technical support for net zero energy assessment and planning funded through the Hawaii Clean Energy Initiative (HCEI). NREL performed a comprehensive assessment to appraise the potential of MCBH Kaneohe Bay to achieve net zero energy status through energy efficiency, renewable energy, and hydrogen vehicle integration. This paper summarizes the results of the assessment and provides energy recommendations. The analysis shows that MCBH Kaneohe Bay has the potential to make significant progress toward becoming a net zero installation. Wind, solar photovoltaics, solar hot water, and hydrogen production were assessed, as well as energy efficiency technologies. Deploying wind turbines is the most cost-effective energy production measure. If the identified energy projects and savings measures are implemented, the base will achieve a 96% site Btu reduction and a 99% source Btu reduction. Using excess wind and solar energy to produce hydrogen for a fleet and fuel cells could significantly reduce energy use and potentially bring MCBH Kaneohe Bay to net zero. Further analysis with an environmental impact and interconnection study will need to be completed. By achieving net zero status, the base will set an example for other military installations, provide environmental benefits, reduce costs, increase energy security, and exceed its energy goals and mandates.

  20. Quaternary InGaAsSb Thermophotovoltaic Diode Technology

    SciTech Connect (OSTI)

    M Dashiell; J Beausang; H Ehsani; G Nichols; D DePoy; L Danielson; P Talamo; K Rahner; E Brown; S Burger; P Fourspring; W Topper; P Baldasaro; C Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; Jizhong Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryl

    2005-01-26

    Thermophotovoltaic (TPV) diodes fabricated from InGaAsSb alloys lattice-matched to GaSb substrates are grown by Metal Organic Vapor Phase Epitaxy (MOVPE). 0.53eV InGaAsSb TPV diodes utilizing front-surface spectral control filters have been tested in a vacuum cavity and a TPV thermal-to-electric conversion efficiency ({eta}{sub TPV}) and a power density (PD) of {eta}{sub TPV} = 19% and PD=0.58 W/cm{sup 2} were measured for T{sub radiator} = 950 C and T{sub diode} = 27 C. Recombination coefficients deduced from minority carrier measurements and the theory reviewed in this article predict a practical limit to the maximum achievable conversion efficiency and power density for 0.53eV InGaAsSb TPV. The limits for the above operating temperatures are projected to be {eta}{sub TPV} = 26% and PD = 0.75 W/cm{sup 2}. These limits are extended to {eta}{sub TPV} = 30% and PD = 0.85W/cm{sup 2} if the diode active region is bounded by a reflective back surface to enable photon recycling and a two-pass optical path length. The internal quantum efficiency of the InGaAsSb TPV diode is close to the theoretically predicted limits, with the exception of short wavelength absorption in GaSb contact layers. Experiments show that the open circuit voltage of the 0.53eV InGaAsSb TPV diodes is not strongly dependent on the device architectures studied in this work where both N/P and P/N double heterostructure diodes have been grown with various acceptor and donor doping levels, having GaSb and AlGaAsSb confinement, and also partial back surface reflectors. Lattice matched InGaAsSb TPV diodes were fabricated with bandgaps ranging from 0.6 to 0.5eV without significant degradation of the open circuit voltage factor, quantum efficiency, or fill factor as the composition approached the miscibility gap. The key diode performance parameter which is limiting efficiency and power density below the theoretical limits in InGaAsSb TPV devices is the open circuit voltage. The open circuit voltages of

  1. Richard King | Department of Energy

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

    Starting with the Solar Decathlon 2007 the competition began including international teams, and in 2010 the first Solar Decathlon Europe was held in Madrid, Spain. The success of ...

  2. King County- Green Building Initiative

    Broader source: Energy.gov [DOE]

    The 2013 Ordinance establishes criteria for energy use, emissions, stormwater management, and construction and demolition materials diversion. The 2010 Ordinance 16769 previously stipulated effic...

  3. Structural transformations in amorphous ↔ crystalline phase change of Ga-Sb alloys

    SciTech Connect (OSTI)

    Edwards, T. G.; Sen, S.; Hung, I.; Gan, Z.; Kalkan, B.; Raoux, S.

    2013-12-21

    Ga-Sb alloys with compositions ranging between ∼12 and 50 at. % Ga are promising materials for phase change random access memory applications. The short-range structures of two such alloys with compositions Ga{sub 14}Sb{sub 86} and Ga{sub 46}Sb{sub 54} are investigated, in their amorphous and crystalline states, using {sup 71}Ga and {sup 121}Sb nuclear magnetic resonance spectroscopy and synchrotron x-ray diffraction. The Ga and Sb atoms are fourfold coordinated in the as-deposited amorphous Ga{sub 46}Sb{sub 54} with nearly 40% of the constituent atoms being involved in Ga-Ga and Sb-Sb homopolar bonding. This necessitates extensive bond switching and elimination of homopolar bonds during crystallization. On the other hand, Ga and Sb atoms are all threefold coordinated in the as-deposited amorphous Ga{sub 14}Sb{sub 86}. Crystallization of this material involves phase separation of GaSb domains in Sb matrix and a concomitant increase in the Ga coordination number from 3 to 4. Results from crystallization kinetics experiments suggest that the melt-quenching results in the elimination of structural “defects” such as the homopolar bonds and threefold coordinated Ga atoms in the amorphous phases of these alloys, thereby rendering them structurally more similar to the corresponding crystalline states compared to the as-deposited amorphous phases.

  4. Nano-scale luminescence characterization of individual InGaN/GaN quantum wells stacked in a microcavity using scanning transmission electron microscope cathodoluminescence

    SciTech Connect (OSTI)

    Schmidt, Gordon Mller, Marcus; Veit, Peter; Bertram, Frank; Christen, Jrgen; Glauser, Marlene; Carlin, Jean-Franois; Cosendey, Gatien; Butt, Raphal; Grandjean, Nicolas

    2014-07-21

    Using cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope at liquid helium temperatures, the optical and structural properties of a 62 InGaN/GaN multiple quantum well embedded in an AlInN/GaN based microcavity are investigated at the nanometer scale. We are able to spatially resolve a spectral redshift between the individual quantum wells towards the surface. Cathodoluminescence spectral linescans allow directly visualizing the critical layer thickness in the quantum well stack resulting in the onset of plastic relaxation of the strained InGaN/GaN system.

  5. Highly transparent ammonothermal bulk GaN substrates

    SciTech Connect (OSTI)

    Jiang, WK; Ehrentraut, D; Downey, BC; Kamber, DS; Pakalapati, RT; Do Yoo, H; D'Evelyn, MP

    2014-10-01

    A novel apparatus has been employed to grow ammonothermal (0001) gallium nitride (GaN) with diameters up to 2 in The crystals have been characterized by x-ray diffraction rocking-curve (XRC) analysis, optical and scanning electron microscopy (SEM), cathodoluminescence (CL), and optical spectroscopy. High crystallinity GaN with FWHM values about 20-50 arcsec and dislocation densities below 1 x 10(5) cm(-2) have been obtained. High optical transmission was achieved with an optical absorption coefficient below 1 cm(-1) at a wavelength of 450 nm. (C) 2014 Elsevier B.V. All rights reserved.

  6. Graphene/GaN diodes for ultraviolet and visible photodetectors

    SciTech Connect (OSTI)

    Lin, Fang; Chen, Shao-Wen; Meng, Jie; Tse, Geoffrey; Fu, Xue-Wen; Xu, Fu-Jun [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Shen, Bo; Liao, Zhi-Min, E-mail: liaozm@pku.edu.cn, E-mail: yudp@pku.edu.cn; Yu, Da-Peng, E-mail: liaozm@pku.edu.cn, E-mail: yudp@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

    2014-08-18

    The Schottky diodes based on graphene/GaN interface are fabricated and demonstrated for the dual-wavelength photodetection of ultraviolet (UV) and green lights. The physical mechanisms of the photoelectric response of the diodes with different light wavelengths are different. For UV illumination, the photo-generated carriers lower the Schottky barrier and increase the photocurrent. For green light illumination, as the photon energy is smaller than the bandgap of GaN, the hot electrons excited in graphene via internal photoemission are responsible for the photoelectric response. Using graphene as a transparent electrode, the diodes show a ?mS photoresponse, providing an alternative route toward multi-wavelength photodetectors.

  7. Simple intrinsic defects in GaAs : numerical supplement.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2012-04-01

    This Report presents numerical tables summarizing properties of intrinsic defects in gallium arsenide, GaAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz and O.A. von Lilienfeld, 'Simple intrinsic defects in GaAs', Modelling Simul. Mater. Sci Eng., Vol. 17, 084007 (2009), and intended for use as reference tables for a defect physics package in device models. The numerical results for density functional theory calculations of properties of simple intrinsic defects in gallium arsenide are presented.

  8. Electronic contribution to friction on GaAs

    SciTech Connect (OSTI)

    Applied Science and Technology Graduate Group, UC Berkeley; Dept. of Materials Sciences and Engineering, UC Berkeley; Salmeron, Miquel; Qi, Yabing; Park, J.Y.; Hendriksen, B.L.M.; Ogletree, D.F.; Salmeron, Miquel

    2008-04-15

    The electronic contribution to friction at semiconductor surfaces was investigated by using a Pt-coated tip with 50nm radius in an atomic force microscope sliding against an n-type GaAs(100) substrate. The GaAs surface was covered by an approximately 1 nm thick oxide layer. Charge accumulation or depletion was induced by the application of forward or reverse bias voltages. We observed a substantial increase in friction force in accumulation (forward bias) with respect to depletion (reverse bias). We propose a model based on the force exerted by the trapped charges that quantitatively explains the experimental observations of excess friction.

  9. Polycrystalline MBE-grown GaAs for solar cells

    SciTech Connect (OSTI)

    Friedman, D.J.; Kurtz, S.R.; Kibbler, A.E.; Al-Jassim, M.; Jones, K.; Keyes, B.; Matson, R.

    1997-02-01

    This paper will discuss initial studies of thin-film GaAs grown by molecular-beam epitaxy for use in developing a thin-film GaAs solar cell. Photocurrent and photoluminescence intensity are related to the material morphology as a function of growth conditions. Growth temperature and V/III ratio have a dramatic effect on the photocurrent. However, it seems likely that even after optimizing such growth parameters, it will be necessary to provide substrates that can provide templates to enhance grain size from the start of thin-film growth. {copyright} {ital 1997 American Institute of Physics.}

  10. Polycrystalline MBE-grown GaAs for solar cells

    SciTech Connect (OSTI)

    Friedman, D. J.; Kurtz, Sarah R.; Kibbler, A. E.; Al-Jassim, M.; Jones, K.; Keyes, B.; Matson, R.

    1997-02-15

    This paper will discuss initial studies of thin-film GaAs grown by molecular-beam epitaxy for use in developing a thin-film GaAs solar cell. Photocurrent and photoluminescence intensity are related to the material morphology as a function of growth conditions. Growth temperature and V/III ratio have a dramatic effect on the photocurrent. However, it seems likely that even after optimizing such growth parameters, it will be necessary to provide substrates that can provide templates to enhance grain size from the start of thin-film growth.

  11. Enhanced sheet carrier densities in polarization controlled AlInN/AlN/GaN/InGaN field-effect transistor on Si (111)

    SciTech Connect (OSTI)

    Hennig, J. Dadgar, A.; Witte, H.; Bläsing, J.; Lesnik, A.; Strittmatter, A.; Krost, A.

    2015-07-15

    We report on GaN based field-effect transistor (FET) structures exhibiting sheet carrier densities of n = 2.9 10{sup 13} cm{sup −2} for high-power transistor applications. By grading the indium-content of InGaN layers grown prior to a conventional GaN/AlN/AlInN FET structure control of the channel width at the GaN/AlN interface is obtained. The composition of the InGaN layer was graded from nominally x{sub In} = 30 % to pure GaN just below the AlN/AlInN interface. Simulations reveal the impact of the additional InGaN layer on the potential well width which controls the sheet carrier density within the channel region of the devices. Benchmarking the In{sub x}Ga{sub 1−x}N/GaN/AlN/Al{sub 0.87}In{sub 0.13}N based FETs against GaN/AlN/AlInN FET reference structures we found increased maximum current densities of I{sub SD} = 1300 mA/mm (560 mA/mm). In addition, the InGaN layer helps to achieve broader transconductance profiles as well as reduced leakage currents.

  12. Strain relaxation in GaN/Al{sub x}Ga{sub 1-x}N superlattices grown by plasma-assisted molecular-beam epitaxy

    SciTech Connect (OSTI)

    Kotsar, Y.; Bellet-Amalric, E.; Das, A.; Monroy, E.; Sarigiannidou, E.

    2011-08-01

    We have investigated the misfit relaxation process in GaN/Al{sub x}Ga{sub 1-x}N (x = 0.1, 0.3, 0.44) superlattices (SL) deposited by plasma-assisted molecular beam epitaxy. The SLs under consideration were designed to achieve intersubband absorption in the mid-infrared spectral range. We have considered the case of growth on GaN (tensile stress) and on AlGaN (compressive stress) buffer layers, both deposited on GaN-on-sapphire templates. Using GaN buffer layers, the SL remains almost pseudomorphic for x = 0.1, 0.3, with edge-type threading dislocation densities below 9 x 10{sup 8} cm{sup -2} to 2 x 10{sup 9} cm{sup -2}. Increasing the Al mole fraction to 0.44, we observe an enhancement of misfit relaxation resulting in dislocation densities above 10{sup 10} cm{sup -2}. In the case of growth on AlGaN, strain relaxation is systematically stronger, with the corresponding increase in the dislocation density. In addition to the average relaxation trend of the SL, in situ measurements indicate a periodic fluctuation of the in-plane lattice parameter, which is explained by the different elastic response of the GaN and AlGaN surfaces to the Ga excess at the growth front. The results are compared with GaN/AlN SLs designed for near-infrared intersubband absorption.

  13. Alloy inhomogeneity and carrier localization in AlGaN sections and AlGaN/AlN nanodisks in nanowires with 240350?nm emission

    SciTech Connect (OSTI)

    Himwas, C.; Hertog, M. den; Dang, Le Si; Songmuang, R.; Monroy, E.

    2014-12-15

    We present structural and optical studies of AlGaN sections and AlGaN/AlN nanodisks (NDs) in nanowires grown by plasma-assisted molecular beam epitaxy. The Al-Ga intermixing at Al(Ga)N/GaN interfaces and the chemical inhomogeneity in AlGaN NDs evidenced by scanning transmission electron microscopy are attributed to the strain relaxation process. This interpretation is supported by the three-dimensional strain distribution calculated by minimizing the elastic energy in the structure. The alloy inhomogeneity increases with the Al content, leading to enhanced carrier localization signatures in the luminescence characteristics, i.e., red shift of the emission, s-shaped temperature dependence, and linewidth broadening. Despite these effects, the emission energy of AlGaN/AlN NDs can be tuned in the 240350?nm range with internal quantum efficiencies around 30%.

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

    SciTech Connect (OSTI)

    Chu, Kuei-Yi; Chiang, Meng-Hsueh Cheng, Shiou-Ying; Liu, Wen-Chau

    2012-02-15

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

  15. High-performance broadband optical coatings on InGaN/GaN solar cells for multijunction device integration

    SciTech Connect (OSTI)

    Young, N. G. Farrell, R. M.; Iza, M.; Speck, J. S.; Perl, E. E.; Keller, S.; Bowers, J. E.; Nakamura, S.; DenBaars, S. P.

    2014-04-21

    We demonstrate InGaN/GaN multiple quantum well solar cells grown by metalorganic chemical vapor deposition on a bulk (0001) substrate with high-performance broadband optical coatings to improve light absorption. A front-side anti-reflective coating and a back-side dichroic mirror were designed to minimize front surface reflections across a broad spectral range and maximize rear surface reflections only in the spectral range absorbed by the InGaN, making the cells suitable for multijunction solar cell integration. Application of optical coatings increased the peak external quantum efficiency by 56% (relative) and conversion efficiency by 37.5% (relative) under 1 sun AM0 equivalent illumination.

  16. Fabrication and Characterization of a Single Hole Transistor in p-type GaAs/AlGaAs Heterostructures

    SciTech Connect (OSTI)

    Tracy, Lisa A; Reno, John L.; Hargett, Terry W.

    2015-09-01

    Most spin qubit research to date has focused on manipulating single electron spins in quantum dots. However, hole spins are predicted to have some advantages over electron spins, such as reduced coupling to host semiconductor nuclear spins and the ability to control hole spins electrically using the large spin-orbit interaction. Building on recent advances in fabricating high-mobility 2D hole systems in GaAs/AlGaAs heterostructures at Sandia, we fabricate and characterize single hole transistors in GaAs. We demonstrate p-type double quantum dot devices with few-hole occupation, which could be used to study the physics of individual hole spins and control over coupling between hole spins, looking towards eventual applications in quantum computing. Intentionally left blank

  17. Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

    SciTech Connect (OSTI)

    Edmunds, C.; Malis, O.; Shao, J.; Shirazi-HD, M.; Manfra, M. J.

    2014-07-14

    We demonstrate THz intersubband absorption (15.6–26.1 meV) in m-plane AlGaN/GaN quantum wells. We find a trend of decreasing peak energy with increasing quantum well width, in agreement with theoretical expectations. However, a blue-shift of the transition energy of up to 14 meV was observed relative to the calculated values. This blue-shift is shown to decrease with decreasing charge density and is, therefore, attributed to many-body effects. Furthermore, a ∼40% reduction in the linewidth (from roughly 8 to 5 meV) was obtained by reducing the total sheet density and inserting undoped AlGaN layers that separate the wavefunctions from the ionized impurities in the barriers.

  18. Inversion-mode GaAs wave-shaped field-effect transistor on GaAs (100) substrate

    SciTech Connect (OSTI)

    Zhang, Jingyun; Si, Mengwei; Wu, Heng; Ye, Peide D.; Lou, Xiabing; Gordon, Roy G.; Shao, Jiayi; Manfra, Michael J.

    2015-02-16

    Inversion-mode GaAs wave-shaped metal-oxide-semiconductor field-effect transistors (WaveFETs) are demonstrated using atomic-layer epitaxy of La{sub 2}O{sub 3} as gate dielectric on (111)A nano-facets formed on a GaAs (100) substrate. The wave-shaped nano-facets, which are desirable for the device on-state and off-state performance, are realized by lithographic patterning and anisotropic wet etching with optimized geometry. A well-behaved 1 μm gate length GaAs WaveFET shows a maximum drain current of 64 mA/mm, a subthreshold swing of 135 mV/dec, and an I{sub ON}/I{sub OFF} ratio of greater than 10{sup 7}.

  19. Degradation of InGaN/GaN laser diodes investigated by micro-cathodoluminescence and micro-photoluminescence

    SciTech Connect (OSTI)

    Meneghini, M. Carraro, S.; Meneghesso, G.; Trivellin, N.; Zanoni, E.; Rossi, F.; Salviati, G.; Schade, L.; Karunakaran, M. A.; Schwarz, U. T.

    2013-12-02

    We present an investigation of the degradation of InGaN/GaN laser diodes grown on a GaN substrate. The results indicate that: (i) Ageing induces a significant increase in the threshold current (Ith) of the lasers, which is attributed to an increase in non-radiative recombination; (ii) Ith increase is correlated to a decrease in the micro-cathodoluminescence signal measured (after the removal of the top metallization) in the region under the ridge; (iii) micro-photoluminescence measurements indicate that constant current stress increases non-radiative recombination within the quantum wells (and not only within the barriers), and induces an increase in the emission wavelength of the degraded region.

  20. Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures

    SciTech Connect (OSTI)

    Estacio, Elmer; Pham, Minh Hong; Takatori, Satoru; Cadatal-Raduban, Marilou; Nakazato, Tomoharu; Shimizu, Toshihiko; Sarukura, Nobuhiko; Somintac, Armando; Defensor, Michael; Awitan, Fritz Christian B.; Jaculbia, Rafael B.; Salvador, Arnel; Garcia, Alipio

    2009-06-08

    We report on the intense terahertz emission from InAs/GaAs quantum dot (QD) structures grown by molecular beam epitaxy. Results reveal that the QD sample emission was as high as 70% of that of a p-type InAs wafer, the most intense semiconductor emitter to date. Excitation wavelength studies showed that the emission was due to absorption in strained undoped GaAs, and corresponds to a two order-of-magnitude enhancement. Moreover, it was found that multilayer QDs emit more strongly compared with a single layer QD sample. At present, we ascribe the intense radiation to huge strain fields at the InAs/GaAs interface.

  1. Current transient spectroscopy for trapping analysis on Au-free AlGaN/GaN Schottky barrier diode

    SciTech Connect (OSTI)

    Hu, J. Groeseneken, G.; Stoffels, S.; Lenci, S.; Venegas, R.; Decoutere, S.; Bakeroot, B.

    2015-02-23

    This paper presents a combined technique of high voltage off-state stress and current transient measurements to investigate the trapping/de-trapping characteristics of Au-free AlGaN/GaN Schottky barrier diodes. The device features a symmetric three-terminal structure with a central anode contact surrounded by two separate cathodes. Under the diode off-state stress conditions, the two separate cathodes were electrically shorted. The de-trapping dynamics was studied by monitoring the recovery of the two-dimensional electron gas (2DEG) current at different temperatures by applying 0.5?V at cathode 2 while grounding cathode 1. During the recovery, the anode contact acts as a sensor of changes in diode leakage current. This leakage variation was found to be mainly due to the barrier height variation. With this method, the energy level and capture cross section of different traps in the AlGaN/GaN Schottky barrier diode can be extracted. Furthermore, the physical location of different trapping phenomena is indicated by studying the variation of the diode leakage current during the recovery. We have identified two distinct trapping mechanisms: (i) electron trapping at the AlGaN surface in the vicinity of the Schottky contact which results in the leakage reduction (barrier height ?{sub B} increase) together with R{sub ON} degradation; (ii) the electron trapping in the GaN channel layer which partially depletes the 2DEG. The physical origin of the two different traps is discussed in the text.

  2. Emission spectra of a laser based on an In(Ga)As/GaAs quantum-dot superlattice

    SciTech Connect (OSTI)

    Sobolev, M. M. Buyalo, M. S.; Nevedomskiy, V. N.; Zadiranov, Yu. M.; Zolotareva, R. V.; Vasil’ev, A. P.; Ustinov, V. M.; Portnoi, E. L.

    2015-10-15

    The spectral characteristics of a laser with an active region based on a ten-layer system of In(Ga)As/GaAs vertically correlated quantum dots with 4.5-nm GaAs spacer layers between InAs quantum dots are studied under the conditions of spontaneous and stimulated emission, depending on the current and the duration of pump pulses. Data obtained by transmission electron microscopy and electroluminescence and absorption polarization anisotropy measurements make it possible to demonstrate that the investigated system of tunnel-coupled InAs quantum dots separated by thin GaAs barriers represents a quantum-dot superlattice. With an increase in the laser pump current, the electroluminescence intensity increases linearly and the spectral position of the electroluminescence maximum shifts to higher energies, which is caused by the dependence of the miniband density-of-states distribution on the pump current. Upon exceeding the threshold current, multimode lasing via the miniband ground state is observed. One of the lasing modes can be attributed to the zero-phonon line, and the other is determined by the longitudinal-optical phonon replica of quantum-dot emission. The results obtained give evidence that, under conditions of the laser pumping of an In(Ga)As/GaAs quantum-dot superlattice, strong coupling between the discrete electron states in the miniband and optical phonons takes place. This leads to the formation of quantum-dot polarons, resulting from the resonant mixing of electronic states whose energy separation is comparable to the optical-phonon energy.

  3. InGaAs/GaAsP strain balanced multi-quantum wires grown on misoriented GaAs substrates for high efficiency solar cells

    SciTech Connect (OSTI)

    Alonso-lvarez, D.; Thomas, T.; Fhrer, M.; Hylton, N. P.; Ekins-Daukes, N. J.; Lackner, D.; Philipps, S. P.; Bett, A. W.; Sodabanlu, H.; Fujii, H.; Watanabe, K.; Sugiyama, M.; Nasi, L.; Campanini, M.

    2014-08-25

    Quantum wires (QWRs) form naturally when growing strain balanced InGaAs/GaAsP multi-quantum wells (MQW) on GaAs [100] 6 misoriented substrates under the usual growth conditions. The presence of wires instead of wells could have several unexpected consequences for the performance of the MQW solar cells, both positive and negative, that need to be assessed to achieve high conversion efficiencies. In this letter, we study QWR properties from the point of view of their performance as solar cells by means of transmission electron microscopy, time resolved photoluminescence and external quantum efficiency (EQE) using polarised light. We find that these QWRs have longer lifetimes than nominally identical QWs grown on exact [100] GaAs substrates, of up to 1??s, at any level of illumination. We attribute this effect to an asymmetric carrier escape from the nanostructures leading to a strong 1D-photo-charging, keeping electrons confined along the wire and holes in the barriers. In principle, these extended lifetimes could be exploited to enhance carrier collection and reduce dark current losses. Light absorption by these QWRs is 1.6 times weaker than QWs, as revealed by EQE measurements, which emphasises the need for more layers of nanostructures or the use light trapping techniques. Contrary to what we expected, QWR show very low absorption anisotropy, only 3.5%, which was the main drawback a priori of this nanostructure. We attribute this to a reduced lateral confinement inside the wires. These results encourage further study and optimization of QWRs for high efficiency solar cells.

  4. Defect-Reduction Mechanism for Improving Radiative Efficiency in InGaN/GaN Light-Emitting Diodes using InGaN Underlayers

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

    Armstrong, Andrew M.; Bryant, Benjamin N.; Crawford, Mary H.; Koleske, Daniel D.; Lee, Stephen R.; Wierer, Jr., Jonathan J.

    2015-04-01

    The influence of a dilute InxGa1-xN (x~0.03) underlayer (UL) grown below a single In0.16Ga0.84N quantum well (SQW), within a light-emitting diode(LED), on the radiative efficiency and deep level defect properties was studied using differential carrier lifetime (DCL) measurements and deep level optical spectroscopy (DLOS). DCL measurements found that inclusion of the UL significantly improved LED radiative efficiency. At low current densities, the non-radiative recombination rate of the LED with an UL was found to be 3.9 times lower than theLED without an UL, while the radiative recombination rates were nearly identical. This, then, suggests that the improved radiative efficiency resultedmore » from reduced non-radiative defect concentration within the SQW. DLOS measurement found the same type of defects in the InGaN SQWs with and without ULs. However, lighted capacitance-voltage measurements of the LEDs revealed a 3.4 times reduction in a SQW-related near-mid-gap defect state for the LED with an UL. Furthermore, quantitative agreement in the reduction of both the non-radiative recombination rate (3.9×) and deep level density (3.4×) upon insertion of an UL corroborates deep level defect reduction as the mechanism for improved LED efficiency.« less

  5. Excitonic transitions in highly efficient (GaIn)As/Ga(AsSb) type-II quantum-well structures

    SciTech Connect (OSTI)

    Gies, S.; Kruska, C.; Berger, C.; Hens, P.; Fuchs, C.; Rosemann, N. W.; Veletas, J.; Stolz, W.; Koch, S. W.; Heimbrodt, W.; Ruiz Perez, A.; Hader, J.; Moloney, J. V.

    2015-11-02

    The excitonic transitions of the type-II (GaIn)As/Ga(AsSb) gain medium of a “W”-laser structure are characterized experimentally by modulation spectroscopy and analyzed using microscopic quantum theory. On the basis of the very good agreement between the measured and calculated photoreflectivity, the type-I or type-II character of the observable excitonic transitions is identified. Whereas the energetically lowest three transitions exhibit type-II character, the subsequent energetically higher transitions possess type-I character with much stronger dipole moments. Despite the type-II character, the quantum-well structure exhibits a bright luminescence.

  6. Properties of H, O and C in GaN

    SciTech Connect (OSTI)

    Pearton, S.J.; Abernathy, C.R.; Lee, J.W.

    1996-04-01

    The electrical properties of the light ion impurities H, O and C in GaN have been examined in both as-grown and implanted material. H is found to efficiently passivate acceptors such as Mg, Ca and C. Reactivation occurs at {ge} 450 C and is enhanced by minority carrier injection. The hydrogen does not leave the GaN crystal until > 800 C, and its diffusivity is relatively high ({approximately} 10{sup {minus}11} cm{sup 2}/s) even at low temperatures (< 200 C) during injection by wet etching, boiling in water or plasma exposure. Oxygen shows a low donor activation efficiency when implanted into GaN, with an ionization level of 30--40 meV. It is essentially immobile up to 1,100 C. Carbon can produce low p-type levels (3 {times} 10{sup 17} cm{sup {minus}3}) in GaN during MOMBE, although there is some evidence it may also create n-type conduction in other nitrides.

  7. Testing a GaAs cathode in SRF gun

    SciTech Connect (OSTI)

    Wang, E.; Kewisch, J.; Ben-Zvi, I.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

    2011-03-28

    RF electron guns with a strained superlattice GaAs cathode are expected to generate polarized electron beams of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface and lower cathode temperature. We plan to install a bulk GaAs:Cs in a SRF gun to evaluate the performance of both the gun and the cathode in this environment. The status of this project is: In our 1.3 GHz 1/2 cell SRF gun, the vacuum can be maintained at nearly 10{sup -12} Torr because of cryo-pumping at 2K. With conventional activation of bulk GaAs, we obtained a QE of 10% at 532 nm, with lifetime of more than 3 days in the preparation chamber and have shown that it can survive in transport from the preparation chamber to the gun. The beam line has been assembled and we are exploring the best conditions for baking the cathode under vacuum. We report here the progress of our test of the GaAs cathode in the SRF gun. Future particle accelerators, such as eRHIC and the ILC require high-brightness, high-current polarized electrons. Strained superlattice GaAs:Cs has been shown to be an efficient cathode for producing polarized electrons. Activation of GaAs with Cs,O(F) lowers the electron affinity and makes it energetically possible for all the electrons, excited into the conduction band that drift or diffuse to the emission surface, to escape into the vacuum. Presently, all operating polarized electron sources, such as the CEBAF, are DC guns. In these devices, the excellent ultra-high vacuum extends the lifetime of the cathode. However, the low field gradient on the photocathode's emission surface of the DC guns limits the beam quality. The higher accelerating gradients, possible in the RF guns, generate a far better beam. Until recently, most RF guns operated at room temperature, limiting the vacuum to {approx}10{sup -9} Torr. This destroys the GaAs's NEA surface. The SRF guns combine the excellent vacuum conditions of DC guns and the high

  8. Quaternary InGaAsSb Thermophotovoltaic Diodes

    SciTech Connect (OSTI)

    MW Dashiell; JF Beausang; H Ehsani; GJ Nichols; DM Depoy; LR Danielson; P Talamo; KD Rahner; EJ Brown; SR Burger; PM Foruspring; WF Topper; PF Baldasaro; CA Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; J Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryi

    2006-03-09

    In{sub x}Ga{sub 1-x}As{sub y}Sb{sub 1-y} thermophotovoltaic (TPV) diodes were grown lattice-matched to GaSb substrates by Metal Organic Vapor Phase Epitaxy (MOVPE) in the bandgap range of E{sub G} = 0.5 to 0.6eV. InGaAsSb TPV diodes, utilizing front-surface spectral control filters, are measured with thermal-to-electric conversion efficiency and power density of {eta}{sub TPV} = 19.7% and PD =0.58 W/cm{sup 2} respectively for a radiator temperature of T{sub radiator} = 950 C, diode temperature of T{sub diode} = 27 C, and diode bandgap of E{sub G} = 0.53eV. Practical limits to TPV energy conversion efficiency are established using measured recombination coefficients and optical properties of front surface spectral control filters, which for 0.53eV InGaAsSb TPV energy conversion is {eta}{sub TPV} = 28% and PD = 0.85W/cm{sup 2} at the above operating temperatures. The most severe performance limits are imposed by (1) diode open-circuit voltage (VOC) limits due to intrinsic Auger recombination and (2) parasitic photon absorption in the inactive regions of the module. Experimentally, the diode V{sub OC} is 15% below the practical limit imposed by intrinsic Auger recombination processes. Analysis of InGaAsSb diode electrical performance vs. diode architecture indicate that the V{sub OC} and thus efficiency is limited by extrinsic recombination processes such as through bulk defects.

  9. Ge doped GaN with controllable high carrier concentration for...

    Office of Scientific and Technical Information (OSTI)

    Ge doped GaN with controllable high carrier concentration for plasmonic applications Citation Details In-Document Search Title: Ge doped GaN with controllable high carrier...

  10. Correlation of DLTS and Performance of GaInNAs Cells

    SciTech Connect (OSTI)

    Kurtz, S.; Johnston, S.; Friedman, D.; Ptak, A.; Geisz, J.; McMahon, W.; Olson, J.; Kibbler, A.; Crandall, R.; Ahrenkiel, R.; Kramer, C.; Young, M.

    2005-01-01

    A four-junction GaInP/GaAs/GaInAsN/Ge solar cell should be able to reach 40% efficiency if each of the junctions can be made with a quality similar to that demonstrated for GaAs. However, the GaInAsN subcell has shown poor performance. Deep-level transient spectroscopy (DLTS) can elucidate recombination centers in a material and could help identify the problem with the GaInAsN. So far, DLTS studies of GaInAsN have shown many peaks. In this paper we compare the performance of the GaInAsN solar cells with the DLTS spectra to identify which DLTS peak is correlated with the device performance.

  11. Bismuth-induced phase control of GaAs nanowires grown by molecular...

    Office of Scientific and Technical Information (OSTI)

    Bismuth-induced phase control of GaAs nanowires grown by molecular beam epitaxy Citation Details In-Document Search Title: Bismuth-induced phase control of GaAs nanowires grown by ...

  12. Site-controlled fabrication of Ga nanodroplets by focused ion beam

    SciTech Connect (OSTI)

    Xu, Xingliang; Wang, Zhiming M.; Wu, Jiang; Li, Handong; Zhou, Zhihua; Wang, Xiaodong

    2014-03-31

    Ga droplets are created by focused ion beam irradiation of GaAs surface. We report that ordered Ga droplets can be formed on the GaAs surface without any implantation damage. The droplets are characterized with bigger sizes than those droplets formed on damaged area. These aligned Ga droplets are formed via the migration of Ga atoms from ion irradiation area to the edge of undamaged GaAs surface and further nucleation into droplets. The morphological evolution and size distribution of these nanodroplets are investigated systematically with different beam irradiation time and incident angles. Based on this method, well positioned Ga nanodroplets, such as chains, are achieved by using focus ion beam patterning. The controllable assembly of droplets on undamaged semiconductor surface can be used to fabricate templates, to fabricate quantum structures and quantum devices by droplet epitaxy technique.

  13. Surface Chemistry of GaP(001) and InP(001) in Contact with Water...

    Office of Scientific and Technical Information (OSTI)

    Surface Chemistry of GaP(001) and InP(001) in Contact with Water Citation Details In-Document Search Title: Surface Chemistry of GaP(001) and InP(001) in Contact with Water ...

  14. Reactive codoping of GaAlInP compound semiconductors (Patent...

    Office of Scientific and Technical Information (OSTI)

    This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and ... A GaAlInP compound semiconductor and a method of producing a GaAlInP compound ...

  15. High-Efficiency GaAs Thin-Film Solar Cell Reliability | Department...

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

    GaAs Thin-Film Solar Cell Reliability High-Efficiency GaAs Thin-Film Solar Cell Reliability Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado ...

  16. Contrasting Behavior of GaP(001) and InP(001) at the Interface...

    Office of Scientific and Technical Information (OSTI)

    Contrasting Behavior of GaP(001) and InP(001) at the Interface with Water Citation Details In-Document Search Title: Contrasting Behavior of GaP(001) and InP(001) at the Interface ...

  17. Structure and magnetic properties of Ce₃(Ni/Al/Ga)₁₁-A...

    Office of Scientific and Technical Information (OSTI)

    ...AlGa)-A new phase with the LaAl structure type Prev Next Title: Structure and magnetic properties of Ce(NiAlGa)-A new phase with the ...

  18. Dislocation confinement in the growth of Na flux GaN on metalorganic...

    Office of Scientific and Technical Information (OSTI)

    Dislocation confinement in the growth of Na flux GaN on metalorganic chemical vapor deposition-GaN Citation Details In-Document Search Title: Dislocation confinement in the growth ...

  19. Electron-limiting defect complex in hyperdoped GaAs: The D D...

    Office of Scientific and Technical Information (OSTI)

    Electron-limiting defect complex in hyperdoped GaAs: The D D X center Prev Next Title: Electron-limiting defect complex in hyperdoped GaAs: The D D X center Authors: Ma, Jie ...

  20. Coexistence of charge-density wave and ferromagnetism in Ni2MnGa...

    Office of Scientific and Technical Information (OSTI)

    Coexistence of charge-density wave and ferromagnetism in Ni2MnGa Citation Details In-Document Search Title: Coexistence of charge-density wave and ferromagnetism in Ni2MnGa ...

  1. Evaluation of CALPUFF nitrogen deposition modeling in the Chesapeake Bay Watershed Area using NADP data

    SciTech Connect (OSTI)

    Garrison, M.; Mayes, P.; Sherwell, J.

    1998-12-31

    The CALMET/CALPUFF modeling system has been used to estimate nitrogen deposition in an area surrounding Baltimore and the northern portion of the Chesapeake Bay. Comprehensive NO{sub x} emissions inventories and meteorological data bases have been developed to conduct the modeling. This paper discusses the results of an evaluation of predicted nitrogen wet deposition rates compared to measured rates at two NADP/NTN sites in Maryland, Wye and White Rock. Underprediction of wet deposition rates is investigated through the use of sensitivity and diagnostic evaluations of model performance. A suggested change to the calculation of NO{sub x} transformation rates involving an alternative specification of minimum NO{sub x} concentrations was made to CALPUFF and the performance evaluation was re-done. Results of the new evaluation show significantly improved model performance, and therefore the modification is tentatively proposed for use in further applications of CALPUFF to the assessment of nitrogen deposition in the Chesapeake Bay watershed.

  2. Recent applications of coiled tubing in remedial wellwork at Prudhoe Bay

    SciTech Connect (OSTI)

    Loveland, K.R.; Bond, A.J.

    1996-12-31

    The vast number of wells and unique operating conditions in Alaska`s Prudhoe Bay field have presented many opportunities for those involved in remedial wellwork. Among the technologies that have either been pioneered, tested, or applied there, coiled tubing (CT) ranks as one of the most long lasting and widely used. This paper highlights the more recent applications of CT in the field. The paper begins with a brief overview of the Prudhoe Bay Unit`s (PBU) CT wellwork program and then follows with discussions on eight CT applications that have been developed or expanded in the last two years. Some are new technology and others are old techniques with a new design. Descriptions and procedures are given for each in addition to performance results thus far.

  3. Influence of Ga content on the structure and anomalous Hall effect of Fe{sub 1−x}Ga{sub x} thin films on GaSb(100)

    SciTech Connect (OSTI)

    Anh Tuan, Duong; Shin, Yooleemi; Viet Cuong, Tran; Cho, Sunglae; Phan, The-Long

    2014-05-07

    The Fe{sub 1−x}Ga{sub x} thin films (x = 0.4, 0.5) have been grown on GaSb(100) substrate using molecular beam epitaxy. An epitaxial film with bcc α-Fe crystal structure (A2) is observed in Fe{sub 0.6}Ga{sub 0.4} film, while an impure Fe{sub 3}Ga phase with DO{sub 3} structure is appeared in Fe{sub 0.5}Ga{sub 0.5} film. The saturated magnetizations at room temperature are observed to be 570 emu/cm{sup 3} and 180 emu/cm{sup 3} and the coercivities to be 170 and 364 Oe for Fe{sub 0.6}Ga{sub 0.4} and Fe{sub 0.5}Ga{sub 0.5}, respectively. A hysteresis trend in Hall resistance vs. magnetic field is observed for Fe{sub 0.5}Ga{sub 0.5} film. However, there is a weak hysteresis noticed in Fe{sub 0.4}Ga{sub 0.6} thin film.

  4. Plasmonic terahertz detectors based on a high-electron mobility GaAs/AlGaAs heterostructure

    SciTech Connect (OSTI)

    Bia?ek, M. Witowski, A. M.; Grynberg, M.; ?usakowski, J.; Orlita, M.; Potemski, M.; Czapkiewicz, M.; Umansky, V.

    2014-06-07

    In order to characterize magnetic field (B) tunable THz plasmonic detectors, spectroscopy experiments were carried out at liquid helium temperatures and high magnetic fields on devices fabricated on a high electron mobility GaAs/AlGaAs heterostructure. The samples were either gated (the gate of a meander shape) or ungated. Spectra of a photovoltage generated by THz radiation were obtained as a function of B at a fixed THz excitation from a THz laser or as a function of THz photon frequency at a fixed B with a Fourier spectrometer. In the first type of measurements, the wave vector of magnetoplasmons excited was defined by geometrical features of samples. It was also found that the magnetoplasmon spectrum depended on the gate geometry which gives an additional parameter to control plasma excitations in THz detectors. Fourier spectra showed a strong dependence of the magnetoplasmon resonance amplitude on the conduction-band electron filling factor which was explained within a model of the electron gas heating with THz radiation. The study allows to define both the advantages and limitations of plasmonic devices based on high-mobility GaAs/AlGaAs heterostructures for THz detection at low temperatures and high magnetic fields.

  5. On the redox origin of surface trapping in AlGaN/GaN high electron mobility transistors

    SciTech Connect (OSTI)

    Gao, Feng; Chen, Di; Tuller, Harry L.; Thompson, Carl V.; Palacios, Toms

    2014-03-28

    Water-related redox couples in ambient air are identified as an important source of the surface trapping states, dynamic on-resistance, and drain current collapse in AlGaN/GaN high electron mobility transistors (HEMTs). Through in-situ X-ray photoelectron spectroscopy (XPS), direct signature of the water-related specieshydroxyl groups (OH) was found at the AlGaN surface at room temperature. It was also found that these species, as well as the current collapse, can be thermally removed above 200?C in vacuum conditions. An electron trapping mechanism based on the H{sub 2}O/H{sub 2} and H{sub 2}O/O{sub 2} redox couples is proposed to explain the 0.5?eV energy level commonly attributed to the surface trapping states. Finally, the role of silicon nitride passivation in successfully removing current collapse in these devices is explained by blocking the water molecules away from the AlGaN surface.

  6. High 400?C operation temperature blue spectrum concentration solar junction in GaInN/GaN

    SciTech Connect (OSTI)

    Zhao, Liang; Detchprohm, Theeradetch; Wetzel, Christian

    2014-12-15

    Transparent wide gap junctions suitable as high temperature, high flux topping cells have been achieved in GaInN/GaN by metal-organic vapor phase epitaxy. In structures of 25 quantum wells (QWs) under AM1.5G illumination, an open circuit voltage of 2.1?V is achieved. Of the photons absorbed in the limited spectral range of <450?nm, 64.2% are converted to electrons collected at the contacts under zero bias. At a fill factor of 45%, they account for a power conversion efficiency of38.6%. Under concentration, the maximum output power density per sun increases from 0.49?mW/cm{sup 2} to 0.51?mW/cm{sup 2} at 40?suns and then falls 0.42?mW/cm{sup 2} at 150?suns. Under external heating, a maximum of 0.59?mW/cm{sup 2} is reached at 250?C. Even at 400?C, the device is fully operational and exceeds room temperature performance. A defect analysis suggests that significantly higher fill factors and extension into longer wavelength ranges are possible with further development. The results prove GaInN/GaN QW solar junctions a viable and rugged topping cell for concentrator photovoltaics with minimal cooling requirements. By capturing the short range spectrum, they reduce the thermal load to any conventional cells stacked behind.

  7. Degradation mechanisms of 2 MeV proton irradiated AlGaN/GaN HEMTs

    SciTech Connect (OSTI)

    Greenlee, Jordan D. Anderson, Travis J.; Koehler, Andrew D.; Weaver, Bradley D.; Kub, Francis J.; Hobart, Karl D.; Specht, Petra; Dubon, Oscar D.; Luysberg, Martina; Weatherford, Todd R.

    2015-08-24

    Proton-induced damage in AlGaN/GaN HEMTs was investigated using energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM), and simulated using a Monte Carlo technique. The results were correlated to electrical degradation using Hall measurements. It was determined by EDS that the interface between GaN and AlGaN in the irradiated HEMT was broadened by 2.2 nm, as estimated by the width of the Al EDS signal compared to the as-grown interface. The simulation results show a similar Al broadening effect. The extent of interfacial roughening was examined using high resolution TEM. At a 2 MeV proton fluence of 6 × 10{sup 14} H{sup +}/cm{sup 2}, the electrical effects associated with the Al broadening and surface roughening include a degradation of the ON-resistance and a decrease in the electron mobility and 2DEG sheet carrier density by 28.9% and 12.1%, respectively.

  8. Effect of proton irradiation energy on AlGaN/GaN metal-oxide semiconductor high electron mobility transistors

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

    Ahn, S.; Dong, C.; Zhu, W.; Kim, B. -j.; Hwang, Ya-Hsi; Ren, F.; Pearton, S. J.; Yang, Gwangseok; Kim, J.; Patrick, Erin; et al

    2015-08-18

    The effects of proton irradiation energy on dc characteristics of AlGaN/GaN metal-oxide semiconductor high electron mobility transistors (MOSHEMTs) using Al2O3 as the gate dielectric were studied. Al2O3/AlGaN/GaN MOSHEMTs were irradiated with a fixed proton dose of 5 × 1015 cm-2 at different energies of 5, 10, or 15 MeV. More degradation of the device dc characteristics was observed for lower irradiation energy due to the larger amount of nonionizing energy loss in the active region of the MOSHEMTs under these conditions. The reductions in saturation current were 95.3%, 68.3%, and 59.8% and reductions in maximum transconductance were 88%, 54.4%, andmore » 40.7% after 5, 10, and 15 MeV proton irradiation, respectively. Both forward and reverse gate leakage current were reduced more than one order of magnitude after irradiation. The carrier removal rates for the irradiation energies employed in this study were in the range of 127–289 cm-1. These are similar to the values reported for conventional metal-gate high-electron mobility transistors under the same conditions and show that the gate dielectric does not affect the response to proton irradiation for these energies.« less

  9. California South/West Bay Area Regional Middle School Science Bowl

    Office of Science (SC) Website

    California South/West Bay Area Regional Middle School Science Bowl National Science Bowl® (NSB) NSB Home About Regional Competitions Rules, Forms, and Resources High School Regionals Middle School Regionals National Finals Volunteers Key Dates Frequently Asked Questions News Media Contact Us WDTS Home Contact Information National Science Bowl® U.S. Department of Energy SC-27/ Forrestal Building 1000 Independence Ave., SW Washington, DC 20585 E: Email Us Middle School Regionals California

  10. EIS-0515: Bay Delta Conservation Plan; Sacramento-San Joaquin Delta, California

    Office of Energy Efficiency and Renewable Energy (EERE)

    The Bureau of Reclamation, U.S. Fish and Wildlife Service, National Marine Fisheries Service, and California Department of Water Resources are jointly preparing an EIS/Environmental Impact Report that analyzes the potential environmental impacts of the proposed Bay Delta Conservation Plan for restoring and protecting water supply reliability, water quality, and ecosystem health. DOE’s Western Area Power Administration is a cooperating agency.

  11. Bay-Area National Labs Team to Tackle Long-Standing Automotive

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

    Hydrogen-Storage Challenge Bay-Area National Labs Team to Tackle Long-Standing Automotive Hydrogen-Storage Challenge - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering

  12. Final Report: Energy Efficiency and Feasibility Study and Resulting Plan for the Bay Mills Indian Community

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

    Report Energy Efficiency Feasibility Study and Resulting Plan for the Bay Mills Indian Community U.S. Department of Energy Tribal Energy Program Award # DE-EE0005173 Project Officer: Lizana K. Pierce lizana.pierce@go.doe.gov Prepared by: Inter-Tribal Council of Michigan, Inc. Environmental Services Division Sault Ste. Marie, MI 49783 Technical Contact: Chris Kushman ckushman@itcmi.org March 2014 1 Executive Summary In 2011 the Inter-Tribal Council of Michigan, Inc. was awarded an Energy

  13. Improved coiled-tubing squeeze-cementing techniques at Prudhoe Bay

    SciTech Connect (OSTI)

    Hornbrook, P.R.; Mason, C.M. )

    1991-04-01

    This paper presents major changes in coiled-tubing squeeze-cementing techniques used in the Prudhoe Bay Unit Western Operating Area (PBUWOA). Changes include introduction of a polymer diluent to replace borax contamination, increased differential pressures placed on squeeze and coil, reduced cement volumes, and incorporation of an inflow test and resqueeze procedure. These changes resulted in increased squeeze effectiveness by reducing equipment and engineering time requirements and by shortening well shut-in time after the workover.

  14. Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii: Assessment and Recommendations

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

    Targeting Net Zero Energy at Marine Corps Base Kaneohe Bay, Hawaii: Assessment and Recommendations K. Burman, A. Kandt, L. Lisell, S. Booth, A. Walker, J. Roberts and J. Falcey Technical Report NREL/ TP-7A40-52897 November 2011 NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401 303-275-3000 *

  15. Bay Area national labs team to tackle long-standing automotive hydrogen

    National Nuclear Security Administration (NNSA)

    storage challenge | National Nuclear Security Administration | (NNSA) Bay Area national labs team to tackle long-standing automotive hydrogen storage challenge Thursday, October 15, 2015 - 1:34pm Sandia National Laboratories chemist Mark Allendorf Sandia National Laboratories chemist Mark Allendorf, shown here at Berkeley Lab's Advanced Light Source facility, is leading the Hydrogen Materials - Advanced Research Consortium (HyMARC) to advance solid-state materials for onboard hydrogen

  16. EIS-0476: Vogtle Electric Generating Plant in Burke County, GA | Department

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

    of Energy 6: Vogtle Electric Generating Plant in Burke County, GA EIS-0476: Vogtle Electric Generating Plant in Burke County, GA February 8, 2012 EIS-0476: Final Environmental Impact Statement Department of Energy Loan Guarantees for Proposed Units 3 and 4 at the Vogtle Electric Generating Plant, Burke County, GA February 25, 2014 EIS-0476: Record of Decision Department of Energy Loan Guarantees for Proposed Units 3 and 4 at the Vogtle Electric Generating Plant, Burke County, GA

  17. Bay Ridge Gardens - Mixed-Humid Affordable Multifamily Housing Deep Energy Retrofit

    SciTech Connect (OSTI)

    Lyons, J.; Moore, M.; Thompson, M.

    2013-08-01

    Under this project, Newport Partners (as part of the BA-PIRC research team) evaluated the installation, measured performance, and cost-effectiveness of efficiency upgrade measures for a tenant-in-place DER at the Bay Ridge multifamily (MF) development in Annapolis, Maryland. The design and construction phase of the Bay Ridge project was completed in August 2012. This report summarizes system commissioning, short-term test results, utility bill data analysis, and analysis of real-time data collected over a one-year period after the retrofit was complete. The Bay Ridge project is comprised of a 'base scope' retrofit which was estimated to achieve a 30%+ savings (relative to pre-retrofit) on 186 apartments, and a 'DER scope' which was estimated to achieve 50% savings (relative to pre-retrofit) on a 12-unit building. The base scope was applied to the entire apartment complex, except for one 12-unit building which underwent the DER scope. A wide range of efficiency measures was applied to pursue this savings target for the DER building, including improvements/replacements of mechanical equipment and distribution systems, appliances, lighting and lighting controls, the building envelope, hot water conservation measures, and resident education. The results of this research build upon the current body of knowledge of multifamily retrofits. Towards this end, the research team has collected and generated data on the selection of measures, their estimated performance, their measured performance, and risk factors and their impact on potential measures.

  18. Manilla Bay 1, 1A, 1A sidetrack; success against all odds

    SciTech Connect (OSTI)

    Durkee, E.F.; Rillera, F.G. )

    1996-01-01

    The discovery of gas in Manila Bay is one of the more significant exploration discoveries in the Western Pacific in recent years. Within the Philippine Archipelago there is no better geographic or economic location to discover gas than at Manila Bay. Geologically, the well has proven that new concepts applied to old areas, in opposition to past beliefs and dogmas is still a valid way to find hydrocarbons. This is especially true re the western margin of the Central Valley of Luzon. New Venture reviewers (more than 100) were generally negative about the possibility of limestone objectives at this setting. The operators eventually drilled the prospect by themselves. The Manila Bay discovery well is on a large basement uplift with more than 2000 feet of vertical closure and 8,000 acres of areal closure at Miocene levels. The geological surprise was that the well drilled through a Pliocene Limestone (700 feet) charged with gas. An estimated in place resource of up to 2 TCF is possible. This is economically very significant for the Philippines as it is only 30 km from downtown Manila, a city of some 10 million people without any indigenous energy supply. Over-pressured fresh water sands induced drilling problems in the initial well MB-1AST and the deeper primary objectives in Middle to Lower Miocene, also predicted to be carbonates, were not reached. A second well to appraise the Pliocene and explore the deep zones will be drilled in early 1996.

  19. Manilla Bay 1, 1A, 1A sidetrack; success against all odds

    SciTech Connect (OSTI)

    Durkee, E.F.; Rillera, F.G.

    1996-12-31

    The discovery of gas in Manila Bay is one of the more significant exploration discoveries in the Western Pacific in recent years. Within the Philippine Archipelago there is no better geographic or economic location to discover gas than at Manila Bay. Geologically, the well has proven that new concepts applied to old areas, in opposition to past beliefs and dogmas is still a valid way to find hydrocarbons. This is especially true re the western margin of the Central Valley of Luzon. New Venture reviewers (more than 100) were generally negative about the possibility of limestone objectives at this setting. The operators eventually drilled the prospect by themselves. The Manila Bay discovery well is on a large basement uplift with more than 2000 feet of vertical closure and 8,000 acres of areal closure at Miocene levels. The geological surprise was that the well drilled through a Pliocene Limestone (700 feet) charged with gas. An estimated in place resource of up to 2 TCF is possible. This is economically very significant for the Philippines as it is only 30 km from downtown Manila, a city of some 10 million people without any indigenous energy supply. Over-pressured fresh water sands induced drilling problems in the initial well MB-1AST and the deeper primary objectives in Middle to Lower Miocene, also predicted to be carbonates, were not reached. A second well to appraise the Pliocene and explore the deep zones will be drilled in early 1996.

  20. Ecological Forecasting in Chesapeake Bay: Using a Mechanistic-Empirical Modelling Approach

    SciTech Connect (OSTI)

    Brown, C. W.; Hood, Raleigh R.; Long, Wen; Jacobs, John M.; Ramers, D. L.; Wazniak, C.; Wiggert, J. D.; Wood, R.; Xu, J.

    2013-09-01

    The Chesapeake Bay Ecological Prediction System (CBEPS) automatically generates daily nowcasts and three-day forecasts of several environmental variables, such as sea-surface temperature and salinity, the concentrations of chlorophyll, nitrate, and dissolved oxygen, and the likelihood of encountering several noxious species, including harmful algal blooms and water-borne pathogens, for the purpose of monitoring the Bay's ecosystem. While the physical and biogeochemical variables are forecast mechanistically using the Regional Ocean Modeling System configured for the Chesapeake Bay, the species predictions are generated using a novel mechanistic empirical approach, whereby real-time output from the coupled physical biogeochemical model drives multivariate empirical habitat models of the target species. The predictions, in the form of digital images, are available via the World Wide Web to interested groups to guide recreational, management, and research activities. Though full validation of the integrated forecasts for all species is still a work in progress, we argue that the mechanisticempirical approach can be used to generate a wide variety of short-term ecological forecasts, and that it can be applied in any marine system where sufficient data exist to develop empirical habitat models. This paper provides an overview of this system, its predictions, and the approach taken.

  1. GaN Initiative for Grid Applications (GIGA)

    SciTech Connect (OSTI)

    Turner, George

    2015-07-03

    For nearly 4 ½ years, MIT Lincoln Laboratory (MIT/LL) led a very successful, DoE-funded team effort to develop GaN-on-Si materials and devices, targeting high-voltage (>1 kV), high-power, cost-effective electronics for grid applications. This effort, called the GaN Initiative for Grid Applications (GIGA) program, was initially made up of MIT/LL, the MIT campus group of Prof. Tomas Palacios (MIT), and the industrial partner M/A Com Technology Solutions (MTS). Later in the program a 4th team member was added (IQE MA) to provide commercial-scale GaN-on-Si epitaxial materials. A basic premise of the GIGA program was that power electronics, for ubiquitous utilization -even for grid applications - should be closer in cost structure to more conventional Si-based power electronics. For a number of reasons, more established GaN-on-SiC or even SiC-based power electronics are not likely to reach theses cost structures, even in higher manufacturing volumes. An additional premise of the GIGA program was that the technical focus would be on materials and devices suitable for operating at voltages > 1 kV, even though there is also significant commercial interest in developing lower voltage (< 1 kV), cost effective GaN-on-Si devices for higher volume applications, like consumer products. Remarkable technical progress was made during the course of this program. Advances in materials included the growth of high-quality, crack-free epitaxial GaN layers on large-diameter Si substrates with thicknesses up to ~5 μm, overcoming significant challenges in lattice mismatch and thermal expansion differences between Si and GaN in the actual epitaxial growth process. Such thick epilayers are crucial for high voltage operation of lateral geometry devices such as Schottky barrier (SB) diodes and high electron mobility transistors (HEMTs). New “Normally-Off” device architectures were demonstrated – for safe operation of power electronics circuits. The trade-offs between lateral and

  2. Ultrasensitive detection of Hg{sup 2+} using oligonucleotide-functionalized AlGaN/GaN high electron mobility transistor

    SciTech Connect (OSTI)

    Cheng, Junjie; Li, Jiadong; Miao, Bin; Wu, Dongmin; Wang, Jine; Pei, Renjun; Wu, Zhengyan

    2014-08-25

    An oligonucleotide-functionalized ion sensitive AlGaN/GaN high electron mobility transistor (HEMT) was fabricated to detect trace amounts of Hg{sup 2+}. The advantages of ion sensitive AlGaN/GaN HEMT and highly specific binding interaction between Hg{sup 2+} and thymines were combined. The current response of this Hg{sup 2+} ultrasensitive transistor was characterized. The current increased due to the accumulation of Hg{sup 2+} ions on the surface by the highly specific thymine-Hg{sup 2+}-thymine recognition. The dynamic linear range for Hg{sup 2+} detection has been determined in the concentrations from 10{sup −14} to 10{sup −8} M and a detection limit below 10{sup −14} M level was estimated, which is the best result of AlGaN/GaN HEMT biosensors for Hg{sup 2+} detection till now.

  3. An inverted AlGaAs/GaAs patterned-Ge tunnel junction cascade concentrator solar cell. Final subcontract report, 1 January 1991--31 August 1992

    SciTech Connect (OSTI)

    Venkatasubramanian, R.

    1993-01-01

    This report describes work to develop inverted-grown Al{sub 0.34}Ga{sub 0.66}As/GaAs cascades. Several significant developments are reported on as follows: (1) The AM1.5 1-sun total-area efficiency of the top Al{sub 0.34}Ga{sub 0.66}As cell for the cascade was improved from 11.3% to 13.2% (NREL measurement [total-area]). (2) The ``cycled`` organometallic vapor phase epitaxy growth (OMVPE) was studied in detail utilizing a combination of characterization techniques including Hall-data, photoluminescence, and secondary ion mass spectroscopy. (3) A technique called eutectic-metal-bonding (EMB) was developed by strain-free mounting of thin GaAs-AlGaAs films (based on lattice-matched growth on Ge substrates and selective plasma etching of Ge substrates) onto Si carrier substrates. Minority-carrier lifetime in an EMB GaAs double-heterostructure was measured as high as 103 nsec, the highest lifetime report for a freestanding GaAs thin film. (4) A thin-film, inverted-grown GaAs cell with a 1-sun AM1.5 active-area efficiency of 20.3% was obtained. This cell was eutectic-metal-bonded onto Si. (5) A thin-film inverted-grown, Al{sub 0.34}Ga{sub 0.66}As/GaAs cascade with AM1.5 efficiency of 19.9% and 21% at 1-sun and 7-suns, respectively, was obtained. This represents an important milestone in the development of an AlGaAs/GaAs cascade by OMVPE utilizing a tunnel interconnect and demonstrates a proof-of-concept for the inverted-growth approach.

  4. Influence of strain induced by AlN nucleation layer on the electrical properties of AlGaN/GaN heterostructures on Si(111) substrate

    SciTech Connect (OSTI)

    Christy, Dennis; Watanabe, Arata; Egawa, Takashi

    2014-10-15

    The crack-free metal-organic chemical vapor deposition (MOCVD) grown AlGaN/GaN heterostructures on Si substrate with modified growth conditions of AlN nucleation layer (NL) and its influence on the electrical and structural properties of conductive GaN layer are presented. From the Hall electrical measurements, a gradual decrease of two-dimensional electron gas (2DEG) concentration near heterointerface as the function of NL thickness is observed possibly due to the reduction in difference of piezoelectric polarization charge densities between AlGaN and GaN layers. It also indicates that the minimum tensile stress and a relatively less total dislocation density for high pressure grown NL can ensure a 20 % increment in mobility at room temperature irrespective of the interface roughness. The thickness and pressure variations in NL and the subsequent changes in growth mode of AlN contributing to the post growth residual tensile stress are investigated using X-ray diffraction and Raman scattering experiments, respectively. The post growth intrinsic residual stress in top layers of heterostructures arises from lattice mismatches, NL parameters and defect densities in GaN. Hence, efforts to reduce the intrinsic residual stress in current conducting GaN layer give an opportunity to further improve the electrical characteristics of AlGaN/GaN device structures on Si.

  5. Absorption enhancement through Fabry-Prot resonant modes in a 430?nm thick InGaAs/GaAsP multiple quantum wells solar cell

    SciTech Connect (OSTI)

    Behaghel, B.; Tamaki, R.; Watanabe, K.; Sodabanlu, H.; Vandamme, N.; Dupuis, C.; Bardou, N.; Cattoni, A.; Okada, Y.; Sugiyama, M.; Collin, S.; Guillemoles, J.-F.

    2015-02-23

    We study light management in a 430?nm-thick GaAs p-i-n single junction solar cell with 10 pairs of InGaAs/GaAsP multiple quantum wells (MQWs). The epitaxial layer transfer on a gold mirror improves light absorption and increases the external quantum efficiency below GaAs bandgap by a factor of four through the excitation of Fabry-Perot resonances. We show a good agreement with optical simulation and achieve around 10% conversion efficiency. We demonstrate numerically that this promising result can be further improved by anti-reflection layers. This study paves the way to very thin MQWs solar cells.

  6. In-plane tunneling anisotropic magnetoresistance in (Ga,Mn)As/GaAs Esaki diodes in the regime of the excess current

    SciTech Connect (OSTI)

    Shiogai, J.; Ciorga, M. Utz, M.; Schuh, D.; Bougeard, D.; Weiss, D.; Kohda, M.; Nitta, J.; Nojima, T.

    2015-06-29

    We investigate the angular dependence of the tunneling anisotropic magnetoresistance in (Ga,Mn)As/n-GaAs spin Esaki diodes in the regime where the tunneling process is dominated by the excess current through midgap states in (Ga,Mn)As. We compare it to similar measurements performed in the regime of band-to-band tunneling. Whereas the latter show biaxial symmetry typical for magnetic anisotropy observed in (Ga,Mn)As samples, the former is dominated by uniaxial anisotropy along the 〈110〉 axes.

  7. Selective saturation of paramagnetic defects in electron- and neutron-irradiated GaAs

    SciTech Connect (OSTI)

    Goltzene, A.; Meyer, B.; Schwab, C.; Beall, R.B.; Newman, R.C.; Whitehouse, J.E.; Woodhead, J.

    1985-06-15

    A comparison of the electron paramagnetic resonance spectra obtained in fast neutron- and electron-irradiated GaAs crystals has confirmed the simultaneous presence of the quadruplet and singlet spectra, ascribed previously to As/sup 4 +//sub Ga/ and V/sup 2 -//sub Ga/ centers. Only in electron-irradiated material, however, are both signals separated by the selective microwave power saturation of the quadruplet. This apparent disparity is ascribed to a difference in the coupling between the two partners in the As/sup 4 +//sub Ga/-V/sup 2 -//sub Ga/ associated complexes.

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

    SciTech Connect (OSTI)

    Vladimir Dmitriev

    2007-06-30

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

  9. Conductivity based on selective etch for GaN devices and applications thereof

    DOE Patents [OSTI]

    Zhang, Yu; Sun, Qian; Han, Jung

    2015-12-08

    This invention relates to methods of generating NP gallium nitride (GaN) across large areas (>1 cm.sup.2) with controlled pore diameters, pore density, and porosity. Also disclosed are methods of generating novel optoelectronic devices based on porous GaN. Additionally a layer transfer scheme to separate and create free-standing crystalline GaN thin layers is disclosed that enables a new device manufacturing paradigm involving substrate recycling. Other disclosed embodiments of this invention relate to fabrication of GaN based nanocrystals and the use of NP GaN electrodes for electrolysis, water splitting, or photosynthetic process applications.

  10. Method of plasma etching Ga-based compound semiconductors

    SciTech Connect (OSTI)

    Qiu, Weibin; Goddard, Lynford L.

    2012-12-25

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

  11. Method of plasma etching GA-based compound semiconductors

    DOE Patents [OSTI]

    Qiu, Weibin; Goddard, Lynford L.

    2013-01-01

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

  12. AlGaAs diode pumped tunable chromium lasers

    DOE Patents [OSTI]

    Krupke, William F.; Payne, Stephen A.

    1992-01-01

    An all-solid-state laser system is disclosed wherein the laser is pumped in the longwave wing of the pump absorption band. By utilizing a laser material that will accept unusually high dopant concentrations without deleterious effects on the crystal lattice one is able to compensate for the decreased cross section in the wing of the absorption band, and the number of pump sources which can be used with such a material increases correspondingly. In a particular embodiment a chromium doped colquiriite-structure crystal such as Cr:LiSrAlF.sub.6 is the laser material. The invention avoids the problems associated with using AlGaInP diodes by doping the Cr:LiSrAlF.sub.6 heavily to enable efficient pumping in the longwave wing of the absorption band with more practical AlGaAs diodes.

  13. Average Structure Evolution of ?-phase Pu-Ga Alloys

    SciTech Connect (OSTI)

    Smith, Alice Iulia; Page, Katharine L.; Gourdon, Olivier; Siewenie, Joan E.; Richmond, Scott; Saleh, Tarik A.; Ramos, Michael; Schwartz, Daniel S.

    2015-03-30

    [Full Text] Plutonium metal is a highly unusual element, exhibiting six allotropes at ambient pressure, from room temperature to its melting point. Many phases of plutonium metal are unstable with temperature, pressure, chemical additions, and time. This strongly affects structure and properties, and becomes of high importance, particularly when considering effects on structural integrity over long time periods. The fcc ?-phase deserves additional attention, not only in the context of understanding the electronic structure of Pu, but also as one of the few high-symmetry actinide phases that can be stabilized down to ambient pressure and room temperature by alloying it with trivalent elements. We will present results on recent work on aging of Pu-2at.%Ga and Pu-7at.%Ga alloys

  14. Photosensitivity of the Ni-n-GaAs Schottky barriers

    SciTech Connect (OSTI)

    Melebaev, D.; Melebaeva, G. D.; Rud', V. Yu. Rud', Yu. V.

    2009-01-15

    The method of chemical deposition is used to form the structures with the Ni-n-GaAs Schottky barrier. The thickness of the Ni layers with a specular outer surface was varied within the range of 150-220 A. It was experimentally observed for the first time that photosensitivity of the obtained barriers with the semitransparent Ni layers illuminated is practically absent in the Fowler region of the spectrum at hv = 0.9-1.5 eV. This circumstance is related mainly to the fact that, in this case, the Ni layer side of the structure was illuminated, and radiation with the photon energy hv < 1.3 eV was effectively reflected from the nickel surface. It is established that the developed Ni-n-GaAs structures can be used as high-efficiency wide-band photoconverters of both visible and ultraviolet radiation.

  15. Formation and properties of porous GaAs

    SciTech Connect (OSTI)

    Schmuki, P.; Lockwood, D.J.; Fraser, J.W.; Graham, M.J.; Isaacs, H.S.

    1996-06-01

    Porous structures on n-type GaAs (100) can be grown electrochemically in chloride-containing solutions. Crystallographic etching of the sample is a precursor stage of the attack. Polarization curves reveal the existanece of a critical onset potential for por formation (PFP). PFP is strongly dependent on the doping level of the sample and presence of surface defects. Good agreement between PFP and breakdown voltage of the space charge layer is found. Surface analysis by EDX, AES, and XPS show that the porous structure consists mainly of GaAs and that anion uptake in the structure can only observed after attackhas been initiated. Photoluminescence measurements reveal (under certain conditions) visible light emission from the porous structure.

  16. The transputer based GA. SP data acquisition system

    SciTech Connect (OSTI)

    Colombo, D.; Avano, B.; DePoli, M.; Maron, G. ); Negro, A.; Parlati, G. )

    1992-04-01

    In this paper, the new data acquisition for the GA.SP detector is presented. It is a distributed system based on a network of 40 T800 and T222 transputers linked to a VME system used for histogram storage. A 100 MBit/s FDDI ring connects the system to UNIX workstations used for the experiment control, histogram display and second level data analysis.

  17. Gallium hole traps in irradiated KTiOPO{sub 4}:Ga crystals

    SciTech Connect (OSTI)

    Grachev, V.; Meyer, M.; Malovichko, G.; Hunt, A. W.

    2014-12-07

    Nominally pure and gallium doped single crystals of potassium titanyl phosphate (KTiOPO{sub 4}) have been studied by Electron Paramagnetic Resonance at low temperatures before and after irradiation. Irradiation with 20?MeV electrons performed at room temperature and liquid nitrogen temperature caused an appearance of electrons and holes. Gallium impurities act as hole traps in KTiOPO{sub 4} creating Ga{sup 4+} centers. Two different Ga{sup 4+} centers were observed, Ga1 and Ga2. The Ga1 centers are dominant in Ga-doped samples. For the Ga1 center, a superhyperfine structure with one nucleus with nuclear spin was registered and attributed to the interaction of gallium electrons with a phosphorus nucleus or proton in its surrounding. In both Ga1 and Ga2 centers, Ga{sup 4+} ions substitute for Ti{sup 4+} ions, but with a preference to one of two electrically distinct crystallographic positions (site selective substitution). The Ga doping eliminates one of the shortcomings of KTP crystalsionic conductivity of bulk crystals. However, this does not improve significantly the resistance of the crystals to electron and ?-radiation.

  18. Characterization and device performance of (AgCu)(InGa)Se2 absorber layers

    SciTech Connect (OSTI)

    Hanket, Gregory; Boyle, Jonathan H.; Shafarman, William N.

    2009-06-08

    The study of (AgCu)(InGa)Se2 absorber layers is of interest in that Ag-chalcopyrites exhibit both wider bandgaps and lower melting points than their Cu counterparts. (AgCu)(InGa)Se2 absorber layers were deposited over the composition range 0 < Ag/(Ag+Cu) < 1 and 0.3 < Ga/(In+Ga) < 1.0 using a variety of elemental co-evaporation processes. Films were found to be singlephase over the entire composition range, in contrast to prior studies. Devices with Ga content 0.3 < Ga/(In+Ga) <0.5 tolerated Ag incorporation up to Ag/(Ag+Cu) = 0.5 without appreciable performance loss. Ag-containing films with Ga/(In+Ga) = 0.8 showed improved device characteristics over Cu-only control samples, in particular a 30-40% increase in short-circuit current. An absorber layer with composition Ag/(Ag+Cu) = 0.75 and Ga/(In+Ga) = 0.8 yielded a device with VOC = 890 mV, JSC = 20.5mA/cm2, fill factor = 71.3%, and ? = 13.0%.

  19. Ga Lithography in Sputtered Niobium for Superconductive Micro and Nanowires.

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

    Henry, Michael David; Lewis, Rupert M.; Wolfley, Steven L.; Monson, Todd C.

    2014-08-18

    This work demonstrates the use of FIB implanted Ga as a lithographic mask for plasma etching of Nb films. Using a highly collimated Ga beam of a FIB, Nb is implanted 12 nm deep with a 14 nm thick Ga layer providing etch selectivity better than 15:1 with fluorine based etch chemistry. Implanted square test patterns, both 10 um by and 10 um and 100 um by 100 um, demonstrate that doses above than 7.5 x 1015 cm-2 at 30 kV provide adequate mask protection for a 205 nm thick, sputtered Nb film. The resolution of this dry lithographic techniquemore » is demonstrated by fabrication of nanowires 75 nm wide by 10 um long connected to 50 um wide contact pads. The residual resistance ratio of patterned Nb films was 3. The superconducting transition temperature, Tc =7.7 K, was measured using MPMS. This nanoscale, dry lithographic technique was extended to sputtered TiN and Ta here and could be used on other fluorine etched superconductors such as NbN, NbSi, and NbTi.« less

  20. Ga lithography in sputtered niobium for superconductive micro and nanowires

    SciTech Connect (OSTI)

    Henry, M. David; Wolfley, Steve; Monson, Todd; Lewis, Rupert

    2014-08-18

    This work demonstrates the use of focused ion beam (FIB) implanted Ga as a lithographic mask for plasma etching of Nb films. Using a highly collimated Ga beam of a FIB, Nb is implanted 12?nm deep with a 14?nm thick Ga layer providing etch selectivity better than 15:1 with fluorine based etch chemistry. Implanted square test patterns, both 10??m by 10??m and 100??m by 100??m, demonstrate that doses above than 7.5??10{sup 15?}cm{sup ?2} at 30?kV provide adequate mask protection for a 205?nm thick, sputtered Nb film. The resolution of this dry lithographic technique is demonstrated by fabrication of nanowires 75?nm wide by 10??m long connected to 50??m wide contact pads. The residual resistance ratio of patterned Nb films was 3. The superconducting transition temperature (T{sub c})?=?7.7?K was measured using a magnetic properties measurement system. This nanoscale, dry lithographic technique was extended to sputtered TiN and Ta here and could be used on other fluorine etched superconductors such as NbN, NbSi, and NbTi.

  1. Crystallographically uniform arrays of ordered (In)GaN nanocolumns

    SciTech Connect (OSTI)

    Gačević, Ž. Bengoechea-Encabo, A.; Albert, S.; Calleja, E.

    2015-01-21

    In this work, through a comparative study of self-assembled (SA) and selective area grown (SAG) (In)GaN nanocolumn (NC) ensembles, we first give a detailed insight into improved crystallographic uniformity (homogeneity of crystallographic tilts and twists) of the latter ones. The study, performed making use of: reflective high energy electron diffraction, X-ray diffraction and scanning electron microscopy, reveals that unlike their SA counterparts, the ensembles of SAG NCs show single epitaxial relationship to both sapphire(0001) and Si(111) underlying substrates. In the second part of the article, making use of X-ray diffraction, we directly show that the selective area growth leads to improved compositional uniformity of InGaN NC ensembles. This further leads to improved spectral purity of their luminescence, as confirmed by comparative macro-photoluminescence measurements performed on SA and SAG InGaN NC ensembles. An improved crystallographic uniformity of NC ensembles facilitates their integration into optoelectronic devices, whereas their improved compositional uniformity allows for their employment in single-color optoelectronic applications.

  2. Optical and quantum efficiency analysis of (Ag,Cu)(In,Ga)Se2 absorber layers

    SciTech Connect (OSTI)

    Boyle, Jonathan; Hanket, Gregory; Shafarman, William

    2009-06-09

    (Ag,Cu)(In,Ga)Se2 thin films have been deposited by elemental co-evaporation over a wide range of compositions and their optical properties characterized by transmission and reflection measurements and by relative shift analysis of quantum efficiency device measurements. The optical bandgaps were determined by performing linear fits of (?h?)2 vs. h?, and the quantum efficiency bandgaps were determined by relative shift analysis of device curves with fixed Ga/(In+Ga) composition, but varying Ag/(Cu+Ag) composition. The determined experimental optical bandgap ranges of the Ga/(In+Ga) = 0.31, 0.52, and 0.82 groups, with Ag/(Cu+Ag) ranging from 0 to 1, were 1.19-1.45 eV, 1.32-1.56 eV, and 1.52-1.76 eV, respectively. The optical bowing parameter of the different Ga/(In+Ga) groups was also determined.

  3. Efficiency calculations of thin-film GaAs solar cells on Si substrates

    SciTech Connect (OSTI)

    Yamaguchi, M.; Amano, C.

    1985-11-01

    Dislocation effect upon the efficiency of single-crystal thin-film AlGaAs-GaAs heteroface solar cells on Si substrates is analyzed. Solar-cell properties are calculated based on a simple model; in the model, dislocations act as recombination centers to reduce the minority-carrier diffusion length in each layer and increase the space-charge layer recombination current. Numerical analysis is also carried out to optimize thin-film AlGaAs-GaAs heteroface solar-cell structures. The fabrication of thin-film AlGaAs-GaAs heteroface solar cells with a practical efficiency larger than 18% on Si substrates appears possible if the dislocation density in the thin-film GaAs layer is less than 10/sup 6/ cm/sup -2/.

  4. Comparative investigation of InGaP/GaAs pseudomorphic field-effect transistors with triple doped-channel profiles

    SciTech Connect (OSTI)

    Tsai, Jung-Hui; Guo, Der-Feng; Lour, Wen-Shiung

    2011-09-15

    In this article, the comparison of DC performance on InGaP/GaAs pseudomorphic field-effect transistors with tripe doped-channel profiles is demonstrated. As compared to the uniform and high-medium-low doped-channel devices, the low-medium-high doped-channel device exhibits the broadest gate voltage swing and the best device linearity because more twodimensional electron gases are formed in the heaviest doped channel to enhance the magnitude of negative threshold voltage. Experimentally, the transconductance within 50% of its maximum value for gate voltage swing is 4.62 V in the low-medium-high doped-channel device, which is greater than 3.58 (3.30) V in the uniform (high-medium-low) doped-channel device.

  5. 1.9 kV AlGaN/GaN Lateral Schottky Barrier Diodes on Silicon

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

    Zhu, Mingda; Song, Bo; Qi, Meng; Hu, Zongyang; Nomoto, Kazuki; Yan, Xiaodong; Cao, Yu; Johnson, Wayne; Kohn, Erhard; Jena, Debdeep; et al

    2015-02-16

    In this letter, we present AlGaN/GaN lateral Schottky barrier diodes on silicon with recessed anodes and dual field plates. A low specific on-resistance RON,SP (5.12 mΩ · cm2), a low turn-on voltage (<0.7 V) and a high reverse breakdown voltage BV (>1.9 kV), were simultaneously achieved in devices with a 25 μm anode/cathode separation, resulting in a power figure-of-merit (FOM) BV2/RON,SP of 727 MW·cm2. The record high breakdown voltage of 1.9 kV is attributed to the dual field plate structure.

  6. Electron heating due to microwave photoexcitation in the high mobility GaAs/AlGaAs two dimensional electron system

    SciTech Connect (OSTI)

    Ramanayaka, A. N.; Mani, R. G.; Wegscheider, W.

    2013-12-04

    We extract the electron temperature in the microwave photo-excited high mobility GaAs/AlGaAs two dimensional electron system (2DES) by studying the influence of microwave radiation on the amplitude of Shubnikov-de Haas oscillations (SdHOs) in a regime where the cyclotron frequency, ?{sub c}, and the microwave angular frequency, ?, satisfy 2? ? ?{sub c} ? 3.5? The results indicate that increasing the incident microwave power has a weak effect on the amplitude of the SdHOs and therefore the electron temperature, in comparison to the influence of modest temperature changes on the dark-specimen SdH effect. The results indicate negligible electron heating under modest microwave photo-excitation, in good agreement with theoretical predictions.

  7. Origin of radiative recombination and manifestations of localization effects in GaAs/GaNAs core/shell nanowires

    SciTech Connect (OSTI)

    Chen, S. L.; Filippov, S.; Chen, W. M.; Buyanova, I. A.; Ishikawa, Fumitaro

    2014-12-22

    Radiative carrier recombination processes in GaAs/GaNAs core/shell nanowires grown by molecular beam epitaxy on a Si substrate are systematically investigated by employing micro-photoluminescence (?-PL) and ?-PL excitation (?-PLE) measurements complemented by time-resolved PL spectroscopy. At low temperatures, alloy disorder is found to cause localization of photo-excited carriers leading to predominance of optical transitions from localized excitons (LE). Some of the local fluctuations in N composition are suggested to lead to strongly localized three-dimensional confining potential equivalent to that for quantum dots, based on the observation of sharp and discrete PL lines within the LE contour. The localization effects are found to have minor influence on PL spectra at room temperature due to thermal activation of the localized excitons to extended states. Under these conditions, photo-excited carrier lifetime is found to be governed by non-radiative recombination via surface states which is somewhat suppressed upon N incorporation.

  8. Terrestrial Concentrator PV Modules Based on GaInP/GaAs/Ge TJ Cells and Minilens Panels

    SciTech Connect (OSTI)

    Rumyantsev, V. D.; Sadchikov, N. A.; Chalov, A. E.; Ionova, E. A.; Friedman, D. J.; Glenn, G.

    2006-01-01

    This paper is a description of research activity in the field of cost-effective modules realizing the concept of very high solar concentration with small-aperture area Fresnel lenses and multijunction III-V cells. Structural simplicity and 'all-glass' design are the guiding principles of the corresponding development. The advanced concentrator modules are made with silicone Fresnel lens panels (from 8 up to 144 lenses, each lens is 4 times 4 cm{sup 2} in aperture area) with composite structure. GaInP/GaAs/Ge triple-junction cells with average efficiencies of 31.1 and 34.7% at 1000 suns were used for the modules. Conversion efficiency as high as 26.3% has been measured indoors in a test module using a newly developed large-area solar simulator.

  9. Short-wave infrared barriode detectors using InGaAsSb absorption material lattice matched to GaSb

    SciTech Connect (OSTI)

    Craig, A. P.; Percy, B.; Marshall, A. R. J.; Jain, M.; Wicks, G.; Hossain, K.; Golding, T.; McEwan, K.; Howle, C.

    2015-05-18

    Short-wave infrared barriode detectors were grown by molecular beam epitaxy. An absorption layer composition of In{sub 0.28}Ga{sub 0.72}As{sub 0.25}Sb{sub 0.75} allowed for lattice matching to GaSb and cut-off wavelengths of 2.9 μm at 250 K and 3.0 μm at room temperature. Arrhenius plots of the dark current density showed diffusion limited dark currents approaching those expected for optimized HgCdTe-based detectors. Specific detectivity figures of around 7×10{sup 10} Jones and 1×10{sup 10} Jones were calculated, for 240 K and room temperature, respectively. Significantly, these devices could support focal plane arrays working at higher operating temperatures.

  10. Degradation mechanisms of Ti/Al/Ni/Au-based Ohmic contacts on AlGaN/GaN HEMTs

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

    Hwang, Ya-Hsi; Ahn, Shihyun; Dong, Chen; Zhu, Weidi; Kim, Byung-Jae; Le, Lingcong; Ren, Fan; Lind, Aaron G.; Dahl, James; Jones, Kevin S.; et al

    2015-04-27

    We investigated the degradation mechanism of Ti/Al/Ni/Au-based Ohmic metallization on AlGaN/GaN high electron mobility transistors upon exposure to buffer oxide etchant (BOE). The major effect of BOE on the Ohmic metal was an increase of sheet resistance from 2.89 to 3.69 Ω/ₜafter 3 min BOE treatment. The alloyed Ohmic metallization consisted 3–5 μm Ni-Al alloy islands surrounded by Au-Al alloy-rings. The morphology of both the islands and ring areas became flatter after BOE etching. Lastly, we used energy dispersive x-ray analysis and Auger electron microscopy to analyze the compositions and metal distributions in the metal alloys prior to and aftermore » BOE exposure.« less

  11. Passivation of deep level states caused by misfit dislocations in InGaAs on patterned GaAs

    SciTech Connect (OSTI)

    Matragrano, M.J.; Watson, G.P.; Ast, D.G. ); Anderson, T.J.; Pathangey, B. )

    1993-03-22

    Deep level transient spectroscopy (DLTS) and cathodoluminescence (CL) were used to study the hydrogen passivation of misfit dislocations in In[sub 0.06]Ga[sub 0.94]As/GaAs heterostructures. The CL observations indicate that hydrogen plasma exposure passivates most, but not all, of the dark line defects existing in the specimen prior to hydrogenation. The concentration of deep level defect states that cannot be passivated is below the detection limit of the DLTS instrument (approximately 4[times]10[sup 12] cm[sup [minus]3]). We find the passivation is stable after anneals at temperatures as high as 600 [degree]C, indicating that hydrogen passivation of misfit dislocations is at least as stable as that of the isolated point defect studied previously with DLTS [W. C. Dautremont-Smith, J. C. Nabity, V. Swaminathan, M. Stavola, J. Chevalier, C. W. Tu, and S. J. Pearton, Appl. Phys. Lett. [bold 49] 1098 (1986)].

  12. Compositionally graded relaxed AlGaN buffers on semipolar GaN for mid-ultraviolet emission

    SciTech Connect (OSTI)

    Young, Erin C.; Wu Feng; Haeger, Daniel A.; Nakamura, Shuji; Denbaars, Steven P.; Cohen, Daniel A.; Speck, James S.; Romanov, Alexey E.

    2012-10-01

    In this Letter, we report on the growth and properties of relaxed, compositionally graded Al{sub x}Ga{sub 1-x}N buffer layers on freestanding semipolar (2021) GaN substrates. Continuous and step compositional grades with Al concentrations up to x = 0.61 have been achieved, with emission wavelengths in the mid-ultraviolet region as low as 265 nm. Coherency stresses were relaxed progressively throughout the grades by misfit dislocation generation via primary (basal) slip and secondary (non-basal) slip systems. Threading dislocation densities in the final layers of the grades were less than 10{sup 6}/cm{sup 2} as confirmed by plan-view transmission electron microscopy and cathodoluminescence studies.

  13. Study of the one dimensional electron gas arrays confined by steps in vicinal GaN/AlGaN heterointerfaces

    SciTech Connect (OSTI)

    Li, Huijie E-mail: sh-yyang@semi.ac.cn; Zhao, Guijuan; Liu, Guipeng; Wei, Hongyuan; Jiao, Chunmei; Yang, Shaoyan E-mail: sh-yyang@semi.ac.cn; Wang, Lianshan; Zhu, Qinsheng

    2014-05-21

    One dimensional electron gas (1DEG) arrays in vicinal GaN/AlGaN heterostructures have been studied. The steps at the interface would lead to the lateral barriers and limit the electron movement perpendicular to such steps. Through a self-consistent Schrdinger-Poisson approach, the electron energy levels and wave functions were calculated. It was found that when the total electron density was increased, the lateral barriers were lowered due to the screening effects by the electrons, and the electron gas became more two-dimension like. The calculated 1DEG densities were compared to the experimental values and good agreements were found. Moreover, we found that a higher doping density is more beneficial to form 1-D like electron gas arrays.

  14. Microstructure of V-based ohmic contacts to AlGaN/GaN heterostructures at a reduced annealing temperature

    SciTech Connect (OSTI)

    Schmid, A. Schroeter, Ch.; Otto, R.; Heitmann, J.; Schuster, M.; Klemm, V.; Rafaja, D.

    2015-02-02

    Ohmic contacts with V/Al/Ni/Au and V/Ni/Au metalization schemes were deposited on AlGaN/GaN heterostructures. The dependence of the specific contact resistance on the annealing conditions and the V:Al thickness ratio was shown. For an optimized electrode stack, a low specific contact resistance of 8.9??10{sup ?6} ? cm{sup 2} was achieved at an annealing temperature of 650?C. Compared to the conventional Ti/Al/Ni/Au contact, this is a reduction of 150?K. The microstructure and contact formation at the AlGaN/metal interface were investigated by transmission electron microscopy including high-resolution micrographs and energy dispersive X-ray analysis. It was shown that for low-resistive contacts, the resistivity of the metalization has to be taken into account. The V:Al thickness ratio has an impact on the formation of different intermetallic phases and thus is crucial for establishing ohmic contacts at reduced annealing temperatures.

  15. Demonstration of isotype GaN/AlN/GaN heterobarrier diodes by NH{sub 3}-molecular beam epitaxy

    SciTech Connect (OSTI)

    Fireman, Micha N.; Browne, David A.; Mazumder, Baishakhi; Speck, James S.; Mishra, Umesh K.

    2015-05-18

    The results of vertical transport through nitride heterobarrier structures grown by ammonia molecular beam epitaxy are presented. Structures are designed with binary layers to avoid the effects of random alloy fluctuations in ternary nitride barriers. The unintentional incorporation of Ga in the AlN growth is investigated by atom probe tomography and is shown to be strongly dependent on both the NH{sub 3} flowrate and substrate temperature growth parameters. Once nominally pure AlN layer growth conditions are achieved, structures consisting of unintentionally doped (UID) GaN spacer layers adjacent to a nominally pure AlN are grown between two layers of n+ GaN, from which isotype diodes are fabricated. Varying the design parameters of AlN layer thickness, UID spacer layer thickness, and threading dislocation density show marked effects on the vertical transport characteristics of these structures. The lack of significant temperature dependence, coupled with Fowler-Nordheim and/or Milliken-Lauritsen analysis, point to a prevalently tunneling field emission mechanism through the AlN barrier. Once flatband conditions in the UID layer are achieved, electrons leave the barrier with significant energy. This transport mechanism is of great interest for applications in hot electron structures.

  16. Enhanced internal quantum efficiency and light extraction efficiency from textured GaN/AlGaN quantum wells grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Cabalu, J.S.; Thomidis, C.; Moustakas, T.D.; Riyopoulos, S.; Zhou Lin; Smith, David J.

    2006-03-15

    GaN/Al{sub 0.2}Ga{sub 0.8}N multiple quantum wells (MQWs) were grown by molecular beam epitaxy on randomly textured and atomically smooth (0001) GaN templates. Smooth and textured GaN templates were deposited on (0001) sapphire substrates by varying the III/V ratio and the substrate temperature during growth by the hydride vapor-phase epitaxy method. We find that the MQWs replicate the texture of the GaN template, which was found to have a Gaussian distribution. The peak photoluminescence intensity from the textured MQWs is always higher than from the smooth MQWs and for GaN (7 nm)/Al{sub 0.2}Ga{sub 0.8}N (8 nm) MQWs, it is 700 times higher than that from similarly produced MQWs on smooth GaN templates. This result is attributed partly to the enhancement in light extraction efficiency and partly to the enhancement in internal quantum efficiency. The origin of the increase in internal quantum efficiency is partly due to the reduction of the quantum-confined Stark effect, since the polarization vector intersects the quantum well (QW) planes at angles smaller than 90 deg. , and partly due to the charge redistribution in the QWs caused by the polarization component parallel to the planes of the QWs.

  17. Selective area epitaxy of monolithic white-light InGaN/GaN quantum well microstripes with dual color emission

    SciTech Connect (OSTI)

    Li, Yuejing; Tong, Yuying; Yang, Guofeng Yao, Chujun; Sun, Rui; Cai, Lesheng; Xu, Guiting; Wang, Jin; Zhang, Qing; Ye, Xuanchao; Wu, Mengting; Wen, Zhiqin

    2015-09-15

    Monolithic color synthesis is demonstrated using InGaN/GaN multiple quantum wells (QWs) grown on GaN microstripes formed by selective area epitaxy on SiO{sub 2} mask patterns. The striped microfacet structure is composed of (0001) and (11-22) planes, attributed to favorable surface polarity and surface energy. InGaN/GaN QWs on different microfacets contain spatially inhomogeneous compositions owing to the diffusion of adatoms among the facets. This unique property allows the microfacet QWs to emit blue light from the (11-22) plane and yellow light from the top (0001) plane, the mixing of which leads to the perception of white light emission.

  18. Temporally and spatially resolved photoluminescence investigation of (112{sup }2) semi-polar InGaN/GaN multiple quantum wells grown on nanorod templates

    SciTech Connect (OSTI)

    Liu, B.; Smith, R.; Athanasiou, M.; Yu, X.; Bai, J.; Wang, T.

    2014-12-29

    By means of time-resolved photoluminescence (PL) and confocal PL measurements, temporally and spatially resolved optical properties have been investigated on a number of In{sub x}Ga{sub 1?x}N/GaN multiple-quantum-well (MQW) structures with a wide range of indium content alloys from 13% to 35% on (112{sup }2) semi-polar GaN with high crystal quality, obtained through overgrowth on nanorod templates. With increasing indium content, the radiative recombination lifetime initially increases as expected, but decreases if the indium content further increases to 35%, corresponding to emission in the green spectral region. The reduced radiative recombination lifetime leads to enhanced optical performance for the high indium content MQWs as a result of strong exciton localization, which is different from the behaviour of c-plane InGaN/GaN MQWs, where quantum confined Stark effect plays a dominating role in emission process.

  19. Final Project Report, Bristol Bay Native Corporation Wind and Hydroelectric Feasibility Study

    SciTech Connect (OSTI)

    Vaught, Douglas J.

    2007-03-31

    The Bristol Bay Native Corporation (BBNC) grant project focused on conducting nine wind resource studies in eight communities in the Bristol Bay region of southwest Alaska and was administered as a collaborative effort between BBNC, the Alaska Energy Authority, Alaska Village Electric Cooperative, Nushagak Electric Cooperative (NEC), Naknek Electric Association (NEA), and several individual village utilities in the region. BBNCs technical contact and the project manager for this study was Douglas Vaught, P.E., of V3 Energy, LLC, in Eagle River, Alaska. The Bristol Bay region of Alaska is comprised of 29 communities ranging in size from the hub community of Dillingham with a population of approximately 3,000 people, to a few Native Alaska villages that have a few tens of residents. Communities chosen for inclusion in this project were Dillingham, Naknek, Togiak, New Stuyahok, Kokhanok, Perryville, Clarks Point, and Koliganek. Selection criteria for conduction of wind resource assessments in these communities included population and commercial activity, utility interest, predicted Class 3 or better wind resource, absence of other sources of renewable energy, and geographical coverage of the region. Beginning with the first meteorological tower installation in October 2003, wind resource studies were completed at all sites with at least one year, and as much as two and a half years, of data. In general, the study results are very promising for wind power development in the region with Class 6 winds measured in Kokhanok; Class 4 winds in New Stuyahok, Clarks Point, and Koliganek; Class 3 winds in Dillingham, Naknek, and Togiak; and Class 2 winds in Perryville. Measured annual average wind speeds and wind power densities at the 30 meter level varied from a high of 7.87 meters per second and 702 watts per square meter in Kokhanok (Class 6 winds), to a low of 4.60 meters per second and 185 watts per square meter in Perryville (Class 2 winds).

  20. H irradiation effects on the GaAs-like Raman modes in GaAs{sub 1-x}N{sub x}/GaAs{sub 1-x}N{sub x}:H planar heterostructures

    SciTech Connect (OSTI)

    Giulotto, E. Geddo, M.; Patrini, M.; Guizzetti, G.; Felici, M.; Capizzi, M.; Polimeni, A.; Martelli, F.; Rubini, S.

    2014-12-28

    The GaAs-like longitudinal optical phonon frequency in two hydrogenated GaAs{sub 1-x}N{sub x}/GaAs{sub 1-x}N{sub x}:H microwire heterostructureswith similar N concentration, but different H dose and implantation conditionshas been investigated by micro-Raman mapping. In the case of GaAs{sub 0.991}N{sub 0.009} wires embedded in barriers where GaAs-like properties are recovered through H irradiation, the phonon frequency in the barriers undergoes a blue shift with respect to the wires. In GaAs{sub 0.992}N{sub 0.008} wires embedded in less hydrogenated barriers, the phonon frequency exhibits an opposite behavior (red shift). Strain, disorder, phonon localization effects induced by H-irradiation on the GaAs-like phonon frequency are discussed and related to different types of N-H complexes formed in the hydrogenated barriers. It is shown that the red (blue) character of the frequency shift is related to the dominant N-2H (N-3H) type of complexes. Moreover, for specific experimental conditions, an all-optical determination of the uniaxial strain field is obtained. This may improve the design of recently presented devices that exploit the correlation between uniaxial stress and the degree of polarization of photoluminescence.

  1. User's guide for SAMMY: a computer model for multilevel r-matrix fits to neutron data using Bayes' equations

    SciTech Connect (OSTI)

    Larson, N. M.; Perey, F. G.

    1980-11-01

    A method is described for determining the parameters of a model from experimental data based upon the utilization of Bayes' theorem. This method has several advantages over the least-squares method as it is commonly used; one important advantage is that the assumptions under which the parameter values have been determined are more clearly evident than in many results based upon least squares. Bayes' method has been used to develop a computer code which can be utilized to analyze neutron cross-section data by means of the R-matrix theory. The required formulae from the R-matrix theory are presented, and the computer implementation of both Bayes' equations and R-matrix theory is described. Details about the computer code and compelte input/output information are given.

  2. GaSb substrates with extended IR wavelength for advanced space based applications

    SciTech Connect (OSTI)

    Allen, Lisa P.; Flint, Patrick; Dallas, Gordon; Bakken, Daniel; Blanchat, Kevin; Brown, Gail J.; Vangala, Shivashankar R.; Goodhue, William D.; Krishnaswami, Kannan

    2009-05-01

    GaSb substrates have advantages that make them attractive for implementation of a wide range of infrared (IR) detectors with higher operating temperatures for stealth and space based applications. A significant aspect that would enable widespread commercial application of GaSb wafers for very long wavelength IR (VLWIR) applications is the capability for transmissivity beyond 15 m. Due largely to the GaSb (antisite) defect and other point defects in undoped GaSb substrates, intrinsic GaSb is still slightly p-type and strongly absorbs in the VLWIR. This requires backside thinning of the GaSb substrate for IR transmissivity. An extremely low n-type GaSb substrate is preferred to eliminate thinning and provide a substrate solution for backside illuminated VLWIR devices. By providing a more homogeneous radial distribution of the melt solute to suppress GaSb formation and controlling the cooling rate, ultra low doped n:GaSb has been achieved. This study examines the surface properties and IR transmission spectra of ultra low doped GaSb substrates at both room and low temperatures. Atomic force microscopy (AFM), homoepitaxy by MBE, and infrared Fourier transform (FTIR) analysis was implemented to examine material quality. As compared with standard low doped GaSb, the ultra low doped substrates show over 50% transmission and consistent wavelength transparency past 23 m with improved %T at low temperature. Homoepitaxy and AFM results indicate the ultra low doped GaSb has a low thermal desorbtion character and qualified morphology. In summary, improvements in room temperature IR transmission and extended wavelength characteristics have been shown consistently for ultra low doped n:GaSb substrates.

  3. Ecological evaluation of proposed dredged material from Winyah Bay, South Carolina

    SciTech Connect (OSTI)

    Ward, J.A.; Gardiner, W.W.; Pinza, M.R.; Word, J.Q.

    1993-10-01

    The navigational channels of Winyah Bay, Georgetown Harbor, South Carolina require dredging to enable normal shipping traffic to use these areas. Before dredging, environmental assessments must be conducted to determine the suitability of this dredged sediment for unconfined, open-water disposal. The Charleston, South Carolina District Office of the US Army Corps of Engineers (USACE) requested that the Battelle/Marine Science Laboratory (MSL) collect sediment samples and conduct the required physical/chemical, toxicological, and bioaccumulation evaluations as required in the 1991 Implementation Manual. This report is intended to provide information required to address potential ecological effects of the Entrance Channel and Inner Harbor sediments proposed disposal in the ocean.

  4. A fuel-based motor vehicle emission inventory for the San Francisco Bay area

    SciTech Connect (OSTI)

    Black, D.R.; Singer, B.C.; Harley, R.A.; Martien, P.T.; Fanai, A.K.

    1997-12-31

    Traditionally, regional motor vehicle emission inventories (MVEI) have been estimated by combining travel demand model and emission factor model predictions. The accuracy of traditional MVEIs is frequently challenged, and development of independent methods for estimating vehicle emissions has been identified as a high priority for air quality research. In this study, an alternative fuel-based MVEI was developed for the San Francisco Bay Area using data from 1990--1992. To estimate CO emissions from motor vehicles in the Bay Area, estimates of gasoline sales were combined with infrared remote sensing measurements of CO and CO{sub 2} exhaust concentrations from over 10,000 light-duty vehicles in summer 1991. Once absolute estimates of CO emissions have been computed, it is possible to use ambient NO{sub x}/CO and NMOC/CO ratios from high traffic areas to estimate emissions for NO{sub x} and NMOC (excluding some resting loss and diurnal evaporative emissions). Ambient ratios were generated from special-study measurements of NMOC and CO in 1990 and 1992, and from routine sampling of NO{sub x} and CO in 1991. All pollutant concentrations were measured on summer mornings at Bay Area monitoring sites in areas with high levels of vehicle traffic and no other significant sources nearby. Stabilized CO emissions calculated by the fuel-based method for cars and light-duty trucks were 1720{+-}420 tons/day. This value is close to California`s MVEI 7G model estimates. Total on-road vehicle emissions of CO in the Bay Area were estimated to be 2900{+-}800 tons/day. Emissions of NMOC were estimated to be 570{+-}200 tons/day, which is 1.6{+-}0.6 times the value predicted by MVEI 7G. In the present study, emissions of NO{sub x} from on-road vehicles were estimated to be 250{+-}90 tons/day, which is 0.6{+-}0.2 times the value predicted by MVEI 7G.

  5. Zero Emission Bay Area (ZEBA) Fuel Cell Bus Demonstration: First Results Report

    SciTech Connect (OSTI)

    Chandler, K.; Eudy, L.

    2011-08-01

    This report documents the early implementation experience for the Zero Emission Bay Area (ZEBA) Demonstration, the largest fleet of fuel cell buses in the United States. The ZEBA Demonstration group includes five participating transit agencies: AC Transit (lead transit agency), Santa Clara Valley Transportation Authority (VTA), Golden Gate Transit (GGT), San Mateo County Transit District (SamTrans), and San Francisco Municipal Railway (Muni). The ZEBA partners are collaborating with the U.S. Department of Energy (DOE) and DOE's National Renewable Energy Laboratory (NREL) to evaluate the buses in revenue service.

  6. Zero Emission Bay Area (ZEBA) Fuel Cell Bus Demonstration Results. Fourth Report

    SciTech Connect (OSTI)

    Eudy, Leslie; Post, Matthew

    2015-07-02

    This report presents results of a demonstration of fuel cell electric buses (FCEB) operating in Oakland, California. Alameda-Contra Costa Transit District (AC Transit) leads the Zero Emission Bay Area (ZEBA) demonstration, which includes 12 advanced-design fuel cell buses and two hydrogen fueling stations. The FCEBs in service at AC Transit are 40-foot, low-floor buses built by Van Hool with a hybrid electric propulsion system that includes a US Hybrid fuel cell power system and EnerDel lithium-based energy storage system. The buses began revenue service in May 2010.

  7. Systematic vegetation change analysis of mangrove dieoff in Florida Bay and southern Everglades National Park

    SciTech Connect (OSTI)

    Colby, M.M.; Sargent, F.J.; Sargent, W.B.

    1997-06-01

    A very brief summary is provided of a project to link hydrological and ecological relationships of the Florida Everglades watershed and the Florida Bay estuary. The creation of vegetation maps and systematic spatial analysis of vegetation and hydrological features will provide information about the interaction between these two ecosystems. The distribution of mangroves, salt marshes, and related vegetative communities are being mapped using existing aerial photography. Historical photographic records are being used to create geographic information system data layers. Changes in the composition of wetlands and vegetative patterns will be compared over a 45-year period.

  8. Preparation for the Recovery of Spent Nuclear Fuel (SNF) at Andreeva Bay, North West Russia - 13309

    SciTech Connect (OSTI)

    Field, D.; McAtamney, N.

    2013-07-01

    Andreeva Bay is located near Murmansk in the Russian Federation close to the Norwegian border. The ex-naval site was used to de-fuel nuclear-powered submarines and icebreakers during the Cold War. Approximately 22,000 fuel assemblies remain in three Dry Storage Units (DSUs) which means that Andreeva Bay has one of the largest stockpiles of highly enriched spent nuclear fuel (SNF) in the world. The high contamination and deteriorating condition of the SNF canisters has made improvements to the management of the SNF a high priority for the international community for safety, security and environmental reasons. International Donors have, since 2002, provided support to projects at Andreeva concerned with improving the management of the SNF. This long-term programme of work has been coordinated between the International Donors and responsible bodies within the Russian Federation. Options for the safe and secure management of SNF at Andreeva Bay were considered in 2004 and developed by a number of Russian Institutes with international participation. This consisted of site investigations, surveys and studies to understand the technical challenges. A principal agreement was reached that the SNF would be removed from the site altogether and transported to Russia's reprocessing facility at Mayak in the Urals. The analytical studies provided the information necessary to develop the construction plan for the site. Following design and regulatory processes, stakeholders endorsed the technical solution in April 2007. This detailed the processes, facilities and equipment required to safely remove the SNF and identified other site services and support facilities required on the site. Implementation of this strategy is now well underway with the facilities in various states of construction. Physical works have been performed to address the most urgent tasks including weather protection over one of the DSUs, installation of shielding over the cells, provision of radiation

  9. Atmospheric nitrogen deposition loadings to the Chesapeake Bay: An initial analysis of the cost effectiveness of control options

    SciTech Connect (OSTI)

    1996-12-31

    The purpose of this project was to examine whether programs to control regional airborne oxides of nitrogen (NOx) are cost-effective ways to reduce nitrogen loads to the Bay compared with other management scenarios. Regional control programs considered in this analysis include: the Low Emission Vehicle (LEV) program of the Ozone Transport Commission (OTC), and a 0.15 pounds (lbs) per million British thermal unit (MMBtu) NOx emission limit applied to large fuel combustors in the Northeast Ozone Transport Region (OTC) States. The effect of extending the OTR programs to wider areas of the country - whose emissions also influence the Bay - was also examined.

  10. Existing Whole-House Solutions Case Study: Bay Ridge Gardens - Mixed Humid Affordable Multifamily Housing Deep Energy Retrofit, Annapolis, Maryland

    SciTech Connect (OSTI)

    2013-10-01

    Under this project, the BA-PIRC research team evaluated the installation, measured performance, and cost-effectiveness of efficiency upgrade measures for a tenant-in-place deep energy retrofit at the Bay Ridge multifamily development in Annapolis, Maryland. The design and construction phase of the Bay Ridge project was completed in August 2012. This case study summarizes system commissioning, short-term test results, utility bill data analysis, and analysis of real-time data collected over a one-year period after the retrofit was complete.

  11. Comparison of single junction AlGaInP and GaInP solar cells grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Masuda, T; Tomasulo, S; Lang, JR; Lee, ML

    2015-03-07

    We have investigated similar to 2.0 eV (AlxGa1-x)(0.51)In0.49P and similar to 1.9 eV Ga0.51In0.49P single junction solar cells grown on both on-axis and misoriented GaAs substrates by molecular beam epitaxy (MBE). Although lattice-matched (AlxGa1-x)(0.51)In0.49P solar cells are highly attractive for space and concentrator photovoltaics, there have been few reports on the MBE growth of such cells. In this work, we demonstrate open circuit voltages (V-oc) ranging from 1.29 to 1.30 V for Ga0.51In0.49P cells, and 1.35-1.37 V for (AlxGa1-x)(0.51)In0.49P cells. Growth on misoriented substrates enabled the bandgap-voltage offset (W-oc = E-g/q - V-oc) of Ga0.51In0.49P cells to decrease from similar to 575 mV to similar to 565 mV, while that of (AlxGa1-x)(0.51)In0.49P cells remained nearly constant at 620 mV. The constant Woc as a function of substrate offcut for (AlxGa1-x)(0.51)In0.49P implies greater losses from non-radiative recombination compared with the Ga0.51In0.49P devices. In addition to larger Woc values, the (AlxGa1-x)(0.51)In0.49P cells exhibited significantly lower internal quantum efficiency (IQE) values than Ga0.51In0.49P cells due to recombination at the emitter/window layer interface. A thin emitter design is experimentally shown to be highly effective in improving IQE, particularly at short wavelengths. Our work shows that with further optimization of both cell structure and growth conditions, MBE-grown (AlxGa1-x)(0.51)In0.49P will be a promising wide-bandgap candidate material for high-efficiency, lattice-matched multi-junction solar cells. (C) 2015 AIP Publishing LLC.

  12. Method of making V.sub.3 Ga superconductors

    DOE Patents [OSTI]

    Dew-Hughes, David

    1980-01-01

    An improved method for producing a vanadium-gallium superconductor wire having aluminum as a component thereof is disclosed, said wire being encased in a gallium bearing copper sheath. The superconductors disclosed herein may be fabricated under normal atmospheres and room temperatures by forming a tubular shaped billet having a core composed of an alloy of vanadium and aluminum and an outer sheath composed of an alloy of copper, gallium and aluminum. Thereafter the entire billet is swage reduced to form a wire therefrom and heat treated to form a layer of V.sub.3 Ga in the interior of the wire.

  13. Structure, transport and thermal properties of UCoGa

    SciTech Connect (OSTI)

    Purwanto, A.; Robinson, R.A.; Prokes, K.

    1994-04-01

    By means of neutron powder diffraction, we find that UCoGa crystallizes in the hexagonal ZrNiAl structure and orders ferromagnetically at low temperatures with magnetic moments stacked along the c axis. The magnetic-ordering temperature is reflected in anomalies in the temperature dependencies of the electrical resistivity and the specific heat at Tc = 47 K. Furthermore, the strong anisotropy in the electrical resistivity for i {parallel} c and i {perpendicular} c indicates a significant contribution of the magnetic anisotropy to the electrical resistivity.

  14. Quantum effects in electron beam pumped GaAs

    SciTech Connect (OSTI)

    Yahia, M. E.; National Institute of Laser Enhanced Sciences , Cairo University ; Azzouz, I. M.; Moslem, W. M.

    2013-08-19

    Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.

  15. Low dimensional GaAs/air vertical microcavity lasers

    SciTech Connect (OSTI)

    Gessler, J.; Steinl, T.; Fischer, J.; Hfling, S.; Schneider, C.; Kamp, M.; Mika, A.; S?k, G.; Misiewicz, J.

    2014-02-24

    We report on the fabrication of gallium arsenide (GaAs)/air distributed Bragg reflector microresonators with indium gallium arsenide quantum wells. The structures are studied via momentum resolved photoluminescence spectroscopy which allows us to investigate a pronounced optical mode quantization of the photonic dispersion. We can extract a length parameter from these quantized states whose upper limit can be connected to the lateral physical extension of the microcavity via analytical calculations. Laser emission from our microcavity under optical pumping is observed in power dependent investigations.

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

    SciTech Connect (OSTI)

    Vernon, S.M. )

    1993-04-01

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

  17. GaInP semiconductor compounds doped with the Sb isovalent impurity

    SciTech Connect (OSTI)

    Skachkov, A. F.

    2015-05-15

    GaInP{sub 1−x}Sb{sub x} layers containing different Sb fractions are produced by metal-organic vaporphase epitaxy on GaAs and Ge substrates. The charge-carrier mobilities in the GaInP{sub 1−x}Sb{sub x} layers are measured at room temperature and 77 K. The room-temperature charge-carrier mobilities in the GaInP{sub 1−x}Sb{sub x} layers additionally doped with donor and acceptor impurities are measured. The photoluminescence peaks of GaInP{sub 1−x}Sb{sub x} are detected. The influence of the Sb impurity on the band gap and charge-carrier mobility in GaInP is determined.

  18. Bay Ridge Gardens - Mixed Humid Affordable Multifamily Housing Deep Energy Retrofit

    SciTech Connect (OSTI)

    Lyons, James; Moore, Mike; Thompson, Margo

    2013-08-01

    Under this project, Newport Partners (as part of the BA-PIRC research team) evaluated the installation, measured performance, and cost effectiveness of efficiency upgrade measures for a tenant-in-place deep energy retrofit (DER) at the Bay Ridge multifamily development in Annapolis, Maryland. This report summarizes system commissioning, short-term test results, utility bill data analysis, and analysis of real-time data collected over a one-year period after the retrofit was complete. The Bay Ridge project is comprised of a "base scope" retrofit which was estimated to achieve a 30%+ savings (relative to pre-retrofit) on 186 apartments, and a "DER scope" which was estimated to achieve 50% savings (relative to pre-retrofit) on a 12-unit building. A wide range of efficiency measures was applied to pursue this savings target for the DER building, including improvements/replacements of mechanical equipment and distribution systems, appliances, lighting and lighting controls, the building envelope, hot water conservation measures, and resident education. The results of this research build upon the current body of knowledge of multifamily retrofits. Towards this end, the research team has collected and generated data on the selection of measures, their estimated performance, their measured performance, and risk factors and their impact on potential measures.

  19. Authorization Basis Safety Classification of Transfer Bay Bridge Crane at the 105-K Basins

    SciTech Connect (OSTI)

    CHAFFEE, G.A.

    2000-04-06

    This supporting document provides the bases for the safety classification for the K Basin transfer bay bridge crane and the bases for the Structures, Systems, and Components (SSC) safety classification. A table is presented that delineates the safety significant components. This safety classification is based on a review of the Authorization Basis (AB). This Authorization Basis review was performed regarding AB and design baseline issues. The primary issues are: (1) What is the AB for the safety classification of the transfer bay bridge crane? (2) What does the SSC safety classification ''Safety Significant'' or ''Safety Significant for Design Only'' mean for design requirements and quality requirements for procurement, installation and maintenance (including replacement of parts) activities for the crane during its expected life time? The AB information on the crane was identified based on review of Department of Energy--Richland Office (RL) and Spent Nuclear Fuel (SNF) Project correspondence, K Basin Safety Analysis Report (SAR) and RL Safety Evaluation Reports (SERs) of SNF Project SAR submittals. The relevant correspondence, actions and activities taken and substantive directions or conclusions of these documents are provided in Appendix A.

  20. Improving p-type doping efficiency in Al{sub 0.83}Ga{sub 0.17}N alloy substituted by nanoscale (AlN){sub 5}/(GaN){sub 1} superlattice with Mg{sub Ga}-O{sub N} δ-codoping: Role of O-atom in GaN monolayer

    SciTech Connect (OSTI)

    Zhong, Hong-xia; Shi, Jun-jie Jiang, Xin-he; Huang, Pu; Ding, Yi-min; Zhang, Min

    2015-01-15

    We calculate Mg-acceptor activation energy E{sub A} and investigate the influence of O-atom, occupied the Mg nearest-neighbor, on E{sub A} in nanoscale (AlN){sub 5}/(GaN){sub 1} superlattice (SL), a substitution for Al{sub 0.83}Ga{sub 0.17}N disorder alloy, using first-principles calculations. We find that the N-atom bonded with Ga-atom is more easily substituted by O-atom and nMg{sub Ga}-O{sub N} (n = 1-3) complexes are favorable and stable in the SL. The O-atom plays a dominant role in reducing E{sub A}. The shorter the Mg-O bond is, the smaller the E{sub A} is. The Mg-acceptor activation energy can be reduced significantly by nMg{sub Ga}-O{sub N} δ-codoping. Our calculated E{sub A} for 2Mg{sub Ga}-O{sub N} is 0.21 eV, and can be further reduced to 0.13 eV for 3Mg{sub Ga}-O{sub N}, which results in a high hole concentration in the order of 10{sup 20} cm{sup −3} at room temperature in (AlN){sub 5}/(GaN){sub 1} SL. Our results prove that nMg{sub Ga}-O{sub N} (n = 2,3) δ-codoping in AlN/GaN SL with ultrathin GaN-layer is an effective way to improve p-type doping efficiency in Al-rich AlGaN.

  1. GaN-on-diamond electronic device reliability: Mechanical and thermo-mechanical integrity

    SciTech Connect (OSTI)

    Liu, Dong; Sun, Huarui; Pomeroy, James W.; Kuball, Martin; Francis, Daniel; Faili, Firooz; Twitchen, Daniel J.

    2015-12-21

    The mechanical and thermo-mechanical integrity of GaN-on-diamond wafers used for ultra-high power microwave electronic devices was studied using a micro-pillar based in situ mechanical testing approach combined with an optical investigation of the stress and heat transfer across interfaces. We find the GaN/diamond interface to be thermo-mechanically stable, illustrating the potential for this material for reliable GaN electronic devices.

  2. GaAsSb/GaAsN short-period superlattices as a capping layer for improved InAs quantum dot-based optoelectronics

    SciTech Connect (OSTI)

    Utrilla, A. D.; Ulloa, J. M. Guzman, A.; Hierro, A.

    2014-07-28

    The application of a GaAsSb/GaAsN short-period superlattice capping layer (CL) on InAs/GaAs quantum dots (QDs) is shown to be an option for providing improved luminescence properties to this system. Separating both GaAsSb and GaAsN ternaries during the growth in 2 monolayer-thick phases solves the GaAsSbN immiscibility-related problems. Strong fluctuations in the CL composition and strain field as well as in the QD size distribution are significantly reduced, and a more regular CL interface is also obtained. Room-temperature (RT) photoluminescence (PL) is obtained for overall N contents as high as 3%, yielding PL peak wavelengths beyond 1.4 μm in samples with a type-II band alignment. High external quantum efficiency electroluminescence and photocurrent from the QD ground state are also demonstrated at RT in a single QD-layer p-i-n device. Thus, it becomes possible to combine and transfer the complementary benefits of Sb- and N-containing GaAs alloys to InAs QD-based optoelectronics.

  3. Electron and hole gas in modulation-doped GaAs/Al{sub 1-x}Ga{sub x}As radial heterojunctions

    SciTech Connect (OSTI)

    Bertoni, Andrea; Royo, Miquel; Mahawish, Farah; Goldoni, Guido

    2011-11-15

    We perform self-consistent Schroedinger-Poisson calculations with exchange and correlation corrections to determine the electron and hole gas in a radial heterojunction formed in a GaAs/AlGaAs core-multi-shell nanowire, which is either n- or p-doped. We show that the electron and hole gases can be tuned to different localizations and symmetries inside the core as a function of the doping density/gate potential. Contrary to planar heterojunctions, conduction electrons do not form a uniform 2D electron gas (2DEG) localized at the GaAs/AlGaAs interface, but rather show a transition between an isotropic, cylindrical distribution deep in the GaAs core (low doping) and a set of six tunnel-coupled quasi-1D channels at the edges of the interface (high doping). Holes, on the other hand, are much more localized at the GaAs/AlGaAs interface. At low doping, they present an additional localization pattern with six separated 2DEGs strips. The field generated by a back-gate may easily deform the electron or hole gas, breaking the sixfold symmetry. Single 2DEGs at one interface or multiple quasi-1D channels are shown to form as a function of voltage intensity, polarity, and carrier type.

  4. Analysis of the GaInP/GaAs/1-eV/Ge Cell and Related Structures for Terrestrial Concentrator Application: Preprint

    SciTech Connect (OSTI)

    Friedman, D. J.; Kurtz, S. R.; Geisz, J. F.

    2002-05-01

    This conference paper describes the analysis of the potential of GaInP/GaAs/1-eV/Ge four-junction solar cell to improve on the efficiency of the state-of-the-art GaInP/GaAs/Ge benchmark. We emphasize three factors: (1) The newly proposed terrestrial concentrator spectrum has a lower ratio of red to blue light than does the old AM1.5 direct standard spectrum. (2) Standard two-layer antireflection coatings do not provide near-zero reflectance over the full spectral range of interest for these devices. (3) GaInNAs junctions used to date for the 1-eV junction have quantum efficiencies less than {approx}75%. These factors all limit the device current, adversely affecting the four-junction efficiency. We discuss strategies for ameliorating this problem, including going to alternate structures such as a GaInP/GaAs/0.9-eV three-junction device.

  5. Relaxation and critical strain for maximum In incorporation in AlInGaN on GaN grown by metal organic vapour phase epitaxy

    SciTech Connect (OSTI)

    Reuters, Benjamin; Finken, M.; Wille, A.; Kalisch, H.; Vescan, A.; Hollaender, B.; Heuken, M.

    2012-11-01

    Quaternary AlInGaN layers were grown on conventional GaN buffer layers on sapphire by metal organic vapour phase epitaxy at different surface temperatures and different reactor pressures with constant precursor flow conditions. A wide range in compositions within 30-62% Al, 5-29% In, and 23-53% Ga was covered, which leads to different strain states from high tensile to high compressive. From high-resolution x-ray diffraction and Rutherford backscattering spectrometry, we determined the compositions, strain states, and crystal quality of the AlInGaN layers. Atomic force microscopy measurements were performed to characterize the surface morphology. A critical strain value for maximum In incorporation near the AlInGaN/GaN interface is presented. For compressively strained layers, In incorporation is limited at the interface as residual strain cannot exceed an empirical critical value of about 1.1%. Relaxation occurs at about 15 nm thickness accompanied by strong In pulling. Tensile strained layers can be grown pseudomorphically up to 70 nm at a strain state of 0.96%. A model for relaxation in compressively strained AlInGaN with virtual discrete sub-layers, which illustrates the gradually changing lattice constant during stress reduction is presented.

  6. ALD TiO2-Al2O3 Stack: An Improved Gate Dielectrics on Ga-polar GaN MOSCAPs

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

    Wei, Daming; Edgar, James H.; Briggs, Dayrl P.; Srijanto, Bernadeta R.; Retterer, Scott T.; Meyer, III, Harry M.

    2014-10-15

    This research focuses on the benefits and properties of TiO2-Al2O3 nano-stack thin films deposited on Ga2O3/GaN by plasma-assisted atomic layer deposition (PA-ALD) for gate dielectric development. This combination of materials achieved a high dielectric constant, a low leakage current, and a low interface trap density. Correlations were sought between the films’ structure, composition, and electrical properties. The gate dielectrics were approximately 15 nm thick and contained 5.1 nm TiO2, 7.1 nm Al2O3 and 2 nm Ga2O3 as determined by spectroscopic ellipsometry. The interface carbon concentration, as measured by x-ray photoelectron spectroscopy (XPS) depth profile, was negligible for GaN pretreated bymore » thermal oxidation in O2 for 30 minutes at 850°C. The RMS roughness slightly increased after thermal oxidation and remained the same after ALD of the nano-stack, as determined by atomic force microscopy. The dielectric constant of TiO2-Al2O3 on Ga2O3/GaN was increased to 12.5 compared to that of pure Al2O3 (8~9) on GaN. In addition, the nano-stack's capacitance-voltage (C-V) hysteresis was small, with a total trap density of 8.74 × 1011 cm-2. The gate leakage current density (J=2.81× 10-8 A/cm2) was low at +1 V gate bias. These results demonstrate the promising potential of plasma ALD deposited TiO2/Al2O3 for serving as the gate oxide on Ga2O3/GaN based MOS devices.« less

  7. Internal quantum efficiency enhancement of GaInN/GaN quantum-well structures using Ag nanoparticles

    SciTech Connect (OSTI)

    Iida, Daisuke; Fadil, Ahmed Ou, Yiyu; Kopylov, Oleksii; Ou, Haiyan; Chen, Yuntian; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi; Akasaki, Isamu

    2015-09-15

    We report internal quantum efficiency enhancement of thin p-GaN green quantum-well structure using self-assembled Ag nanoparticles. Temperature dependent photoluminescence measurements are conducted to determine the internal quantum efficiency. The impact of excitation power density on the enhancement factor is investigated. We obtain an internal quantum efficiency enhancement by a factor of 2.3 at 756 W/cm{sup 2}, and a factor of 8.1 at 1 W/cm{sup 2}. A Purcell enhancement up to a factor of 26 is estimated by fitting the experimental results to a theoretical model for the efficiency enhancement factor.

  8. Enhanced conversion efficiency in wide-bandgap GaNP solar cells

    SciTech Connect (OSTI)

    Sukrittanon, Supanee; Liu, Ren; Ro, Yun Goo; Pan, Janet L.; Jungjohann, Katherine Leigh; Tu, Charles W.; Dayeh, Shadi A.

    2015-10-12

    In this study, we demonstrate –2.05 eV dilute nitride GaNP solar cells on GaP substrates for potential use as the top junction in dual-junction integrated cells on Si. By adding a small amount of N into indirect-bandgap GaP, GaNP has several extremely important attributes: a direct-bandgap that is also tunable, and easily attained lattice-match with Si. Our best GaNP solar cell ([N] –1.8%, Eg –2.05 eV) achieves an efficiency of 7.9%, even in the absence of a window layer. This GaNP solar cell's efficiency is 3× higher than the most efficient GaP solar cell to date and higher than other solar cells with similar direct bandgap (InGaP, GaAsP). Through a systematic study of the structural, electrical, and optical properties of the device, efficient broadband optical absorption and enhanced solar cell performance are demonstrated.

  9. Antimonide-Based Long-Wavelength Lasers on GaAs Substrates

    SciTech Connect (OSTI)

    KLEM,JOHN F.; Blum, O.

    2000-08-17

    We have investigated the use of GaAsSb in edge-emitting laser active regions, in order to obtain lasing near 1.3 {micro}m. Single quantum well GaAsSb devices display electroluminescence at wavelengths as long as 1.34 {micro}m, but substantial blueshifts occur under high injection conditions. GaAsSb single quantum well edge emitters have been obtained which lase at 1.275 {micro}m with a room-temperature threshold current density as low as 535 A/cm{sup 2}. Modification of the basic GaAsSb/GaAs structure with the addition of InGaAs layers results in a strongly type-II band alignment which can be used to further extend the emission wavelength of these devices. Using GaAsSb/InGaAs active regions, lasers emitting at 1.17 {micro}m have been obtained with room-temperature threshold current densities of 120 A/cm{sup 2}, and devices operating at 1.29 {micro}m have displayed thresholds as low as 375 A/cm{sup 2}. Characteristic temperatures for devices employing various GaAsSb-based active regions have been measured to be 60-73 K.

  10. In-situ crystallization of GeTe\\GaSb phase change memory stacked films

    SciTech Connect (OSTI)

    Velea, A.; Borca, C. N.; Grolimund, D.; Socol, G.; Galca, A. C.; Popescu, M.; Bokhoven, J. A. van

    2014-12-21

    Single and double layer phase change memory structures based on GeTe and GaSb thin films were deposited by pulsed laser deposition (PLD). Their crystallization behavior was studied using in-situ synchrotron techniques. Electrical resistance vs. temperature investigations, using the four points probe method, showed transition temperatures of 138 °C and 198 °C for GeTe and GaSb single films, respectively. It was found that after GeTe crystallization in the stacked films, Ga atoms from the GaSb layer diffused in the vacancies of the GeTe crystalline structure. Therefore, the crystallization temperature of the Sb-rich GaSb layer is decreased by more than 30 °C. Furthermore, at 210 °C, the antimony excess from GaSb films crystallizes as a secondary phase. At higher annealing temperatures, the crystalline Sb phase increased on the expense of GaSb crystalline phase which was reduced. Extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges revealed changes in their local atomic environments as a function of the annealing temperature. Simulations unveil a tetrahedral configuration in the amorphous state and octahedral configuration in the crystalline state for Ge atoms, while Ga is four-fold coordinated in both as-deposited and annealed samples.

  11. Interface Reactions and Electrical Characteristics of Au/GaSb Contacts

    SciTech Connect (OSTI)

    H. Ehsani; R.J. Gutmann; G.W. Charache

    2000-07-07

    The reaction of Au with GaSb occurs at a relatively low temperature (100 C). Upon annealing, a AuSb{sub 2} compound and several Au-Ga phases are produced. Phase transitions occur toward higher Ga concentration with increasing annealing temperatures. Furthermore, the depth of the contact also increases with increased annealing temperature. They found that the AuSb{sub 2} compound forms on the GaSb surface, with the compound crystal partially ordered with respect to the substrate. The transition of Schottky- to ohmic-contact behavior in Au/n-type GaSb occurs simultaneously with the formation of the AuGa compound at about a 250 C annealing temperature. This ohmic contact forms without the segregation of dopants at the metallic compound/GaSb interface. Therefore it is postulated that transition from Schottky- to ohmic-contact behavior is obtained through a series of tunneling transitions of electrons through defects in the depletion region in the Au/n-type GaSb contacts. Contact resistivities of 6-7 x 10{sup -6} {Omega}-cm{sup 2} were obtained with the annealing temperature between 300 and 350 C for 30 seconds. In Au/p-type GaSb contacts, the resistivity was independent of the annealing temperature. This suggested that the carrier transport in p-type contact dominated by thermionic emission.

  12. Structural defects in GaN revealed by Transmission Electron Microscopy

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

    Liliental-Weber, Zuzanna

    2014-09-08

    This paper reviews the various types of structural defects observed by Transmission Electron Microscopy in GaN heteroepitaxial layers grown on foreign substrates and homoepitaxial layers grown on bulk GaN substrates. The structural perfection of these layers is compared to the platelet self-standing crystals grown by High Nitrogen Pressure Solution. Defects in undoped and Mg doped GaN are discussed. Lastly, some models explaining the formation of inversion domains in heavily Mg doped layers that are possible defects responsible for the difficulties of p-doping in GaN are also reviewed.

  13. Double Power Output for GaAs Solar Cells Embedded in Luminescent...

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

    Double power output of bifacial thin-film GaAs microscale solar cells is achieved by embedding in luminescent waveguides (LSCs) with light- trapping backside reflectors (BSRs). ...

  14. Vacancy defects in as-grown and neutron irradiated GaP studied by positrons

    SciTech Connect (OSTI)

    Dlubek, G.; Bruemmer, O.; Polity, A.

    1986-08-18

    Positron lifetime and Doppler-broadening measurements have been used to study vacancy defects in n-italic-type GaP. Vacancies in the P sublattice with a concentration of some 10/sup 17/ cm/sup -3/ were observed in as-grwon GaP. The vacancies disappear during annealing at 500--800 /sup 0/C. In neutron-irradiated GaP positrons are trapped by Ga vacancies which anneal out in two stages situated at 300--550 /sup 0/C and 550--700 /sup 0/C.

  15. Influence of Growth Temperature on AlGaN Multi-Quantum Well Point...

    Office of Scientific and Technical Information (OSTI)

    Influence of Growth Temperature on AlGaN Multi-Quantum Well Point Defect Incorporation and Photoluminescence Efficiency. Citation Details In-Document Search Title: Influence of ...

  16. Enhanced conversion efficiency in wide-bandgap GaNP solar cells

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

    Sukrittanon, Supanee; Liu, Ren; Ro, Yun Goo; Pan, Janet L.; Jungjohann, Katherine Leigh; Tu, Charles W.; Dayeh, Shadi A.

    2015-10-12

    In this study, we demonstrate –2.05 eV dilute nitride GaNP solar cells on GaP substrates for potential use as the top junction in dual-junction integrated cells on Si. By adding a small amount of N into indirect-bandgap GaP, GaNP has several extremely important attributes: a direct-bandgap that is also tunable, and easily attained lattice-match with Si. Our best GaNP solar cell ([N] –1.8%, Eg –2.05 eV) achieves an efficiency of 7.9%, even in the absence of a window layer. This GaNP solar cell's efficiency is 3× higher than the most efficient GaP solar cell to date and higher than othermore » solar cells with similar direct bandgap (InGaP, GaAsP). Through a systematic study of the structural, electrical, and optical properties of the device, efficient broadband optical absorption and enhanced solar cell performance are demonstrated.« less

  17. Structural defects in GaN revealed by Transmission Electron Microscopy

    SciTech Connect (OSTI)

    Liliental-Weber, Zuzanna

    2014-04-18

    This paper reviews the various types of structural defects observed by Transmission Electron Microscopy in GaN heteroepitaxial layers grown on foreign substrates and homoepitaxial layers grown on bulk GaN substrates. The structural perfection of these layers is compared to the platelet self-standing crystals grown by High Nitrogen Pressure Solution. Defects in undoped and Mg doped GaN are discussed. Some models explaining the formation of inversion domains in heavily Mg doped layers that are possible defects responsible for the difficulties of p-doping in GaN are also reviewed.

  18. Investigation of new approaches for InGaN growth with high indium...

    Office of Scientific and Technical Information (OSTI)

    issues of phase separation and high dislocation density in InGaN-based PIN solar cells. ... Language: English Subject: 36 MATERIALS SCIENCE; 14 SOLAR ENERGY; COMPARATIVE EVALUATIONS; ...

  19. Relaxation of compressively strained AlGaN by inclined threading...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Relaxation of compressively strained AlGaN by inclined threading dislocations. Citation Details ... Publication Date: 2005-06-01 OSTI Identifier: 973648 Report ...

  20. High-temperature luminescence in an n-GaSb/n-InGaAsSb/p-AlGaAsSb light-emitting heterostructure with a high potential barrier

    SciTech Connect (OSTI)

    Petukhov, A. A., E-mail: andrey-rus29@rambler.ru; Zhurtanov, B. E.; Kalinina, K. V.; Stoyanov, N. D.; Salikhov, H. M.; Mikhailova, M. P.; Yakovlev, Yu. P. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-09-15

    The electroluminescent properties of an n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with a high potential barrier in the conduction band (large conduction-band offset) at the n-GaSb/n-InGaAsSb type-II heterointerface ({Delta}E{sub c} = 0.79 eV) are studied. Two bands with peaks at 0.28 and 0.64 eV at 300 K, associated with radiative recombination in n-InGaAsSb and n-GaSb, respectively, are observed in the electroluminescence (EL) spectrum. In the entire temperature range under study, T = 290-480 K, additional electron-hole pairs are formed in the n-InGaAsSb active region by impact ionization with hot electrons heated as a result of the conduction-band offset. These pairs contribute to radiative recombination, which leads to a nonlinear increase in the EL intensity and output optical power with increasing pump current. A superlinear increase in the emission power of the long-wavelength band is observed upon heating in the temperature range T = 290-345 K, and a linear increase is observed at T > 345 K. This work for the first time reports an increase in the emission power of a light-emitting diode structure with increasing temperature. It is shown that this rise is caused by a decrease in the threshold energy of the impact ionization due to narrowing of the band gap of the active region.