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Exploring LED Efficiency at BNL's CFN

Kim Kisslinger

CFN's Kim Kisslinger, seen here with a focused-ion beam instrument, reduced the InGaN samples to a thickness of just 20 nanometers to prepare them for electron microscopy.

From the high-resolution glow of flat screen televisions to light bulbs that last for years, light-emitting diodes (LEDs) continue to transform technology. The celebrated efficiency and versatility of LEDs and other solid-state technologies including laser diodes and solar photovoltaics make them increasingly popular. Their full potential, however, remains untapped, in part because the semiconductor alloys that make these devices work continue to puzzle scientists.

A contentious controversy has surrounded the high intensity of one leading LED semiconductor – indium gallium nitride (InGaN) – with experts split on how the material is able to provide the LED’s remarkable efficiency. Using state-of-the-art instruments at the Center for Functional Nanomaterials (CFN), researchers recently established a foolproof method for investigating InGaN materials. These non-destructive imaging techniques can now be used to help unlock the secrets of this amazing alloy.

The InGaN alloy is of extreme interest to scientists and inventors in the semiconductor and solid-state lighting fields. It has the ability to emit light over a wide range of wavelengths – manifesting as different colors simply by changing the relative amounts of indium and gallium in the material. Scientists are exploring the fundamentals of light emission in this material, as well as pushing the frontiers of the exciting field of excitonics, where light and electrons interact both to store energy and mediate its transfer in a wide range of materials. A deeper understanding of excitonics could impact many real-world devices including: blue and green LEDs, ultra-high-efficiency solar photovoltaics, laser pointers and Blu-ray writers, and ultraviolet LEDs for medical and industrial applications.

To learn more about this exciting research read the full article.

2013-4164  |  INT/EXT  |  Media & Communications Office

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Study to Measure Impacts from Biomass Burning

global fire activity

Global fire activity for 10 days, April 30-May 9, 2012. Illustration taken from Art Sedlacek's presentation at the Atmospheric System Research Annual Meeting, 2013. (Courtesy: C. Ichoku and R. Kahn)

This summer and fall, a team of researchers led by BNL scientists will conduct a field campaign in the skies over the Pacific Northwest and Tennessee to measure the evolution of aerosols in wildfires and prescribed agriculture burns. 

Sponsored by the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility, the Biomass Burning Observation Project (BBOP) will study the properties of aerosols generated in biomass burning events.  Bio-burning releases soot, organic aerosols and heat-trapping gases that are recognized to perturb Earth's climate both directly, through scattering and absorption of incoming shortwave radiation, and indirectly, by influencing cloud formation and precipitation.

"Biomass burns are important because they contribute large fractions of organic aerosols, generate a very rich suite of chemicals, and produce soot and tarballs," BNL’s Arthur Sedlacek said. "We want to understand how these burning events impact aerosol emissions and how these emissions impact climate."

The researchers will conduct measurements near active fires, where limited observations indicate rapid changes in aerosol properties, and in biomass burning plumes more than five hours old. Aerosol properties and their evolution will be determined as a function of fire type, defined according to fuel and the mix of flaming and smoldering combustion at the source.

Wildfires produce approximately 40 percent of all soot, which has been shown to contribute to global warming, and different stages of burns emit different types of aerosols. In addition, aerosols released from natural fires are different from manmade ones.

Scientists believe that aerosol effects on clouds may change the regional and global circulation systems that constitute Earth's climate. The BBOP researchers hope that their field study will contribute to a better understanding of how aerosols emitted by different types of fires may contribute to climate change.

To learn more visit: http://www.bnl.gov/newsroom/news.php?a=11558 and http://www.arm.gov/news/features/post/21692 

2013-4165  |  INT/EXT  |  Media & Communications Office

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BNL's Newest Science Facility Wins Multiple Construction Awards

NSLS-II

As it nears completion, BNL’s state-of-the-art National Synchrotron Light Source II (NSLS-II) and the firms that designed and built it – HDR Architecture, Inc. and general contractor TORCON, Inc. – have received several awards recognizing its design and construction. 

In addition to receiving Leadership in Energy and Environmental Design (LEED) Gold certification by the U.S. Green Building Council in March, NSLS-II has been awarded with: 

Grand Award, 2013
National Chapter of the American Council of Engineering Companies 

Diamond Award, 2013
American Council of Engineering Companies of New York

Building of the Year Award, 2013
American Society of Civil Engineers, Long Island Branch

Owner-Managed Project of the Year, 2013
Construction Management Association of America, New York/New Jersey Chapter

NSLS-II, under construction since 2009, is the largest domestic capital project for the U.S. Department of Energy’s Office of Science. The project created nearly 1,250 construction jobs and the completed facility will provide some 450 scientific, engineering, and support jobs. Purchases totaled $130 million in labor and $135 million in materials. NSLS-II is scheduled to begin operating in 2015.

2013-4166  |  INT/EXT  |  Media & Communications Office

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Happenings

  • July and August — Community Advisory Council summer break. Next meeting will be September 12, 2013.
  • August 4 — Our last Summer Sunday – visit the Relativistic Heavy Ion Collider (RHIC), where physicists re-create the conditions of the universe as they believe it existed microseconds after the Big Bang! 10 AM to 3 PM.
  • August 14 — Noon recital. The Attacca Quartet, the Juilliard Graduate Resident String Quartet, will perform. Noon, Berkner Hall Auditorium.

*The events above are free and open to the public. Visitors 16 and older must bring a photo ID for access to BNL events.

2013-4167  |  INT/EXT  |  Media & Communications Office