Doe Science news source
The DOE Science News Source is a Newswise initiative to promote research news from the Office of Science of the DOE to the public and news media.
  • 2017-11-20 16:30:27
  • Article ID: 685537

Quantum Dots Amplify Light with Electrical Pumping

Los Alamos achieves light amplification with electrically stimulated quantum dots, critical step towards solution-processible laser diodes

  • Credit: LANL

    A collage showing contains a transmission electron microscopy image of the improved quantum dot and its representation (left), the schematic of the device which nicely illustrates “current-focusing” idea (middle), and the device under operation (right).

LOS ALAMOS, N.M., November 20, 2017— In a breakthrough development, Los Alamos scientists have shown that they can successfully amplify light using electrically excited films of the chemically synthesized semiconductor nanocrystals known as quantum dots.  The quantum dot films are integrated into devices much like the now-ubiquitous light-emitting diodes (LEDs), but, in this case designed to sustain the high current densities required for achieving the optical-gain regime. One sees laser diodes every day in laser pointers, barcode readers and the like, and a  key element of such devices is an optical-gain medium, which instead of absorbing incident light, amplifies it.

“Optical gain with electrically excited quanum dots is now a reality,” said Victor Klimov, head of the quantum dot team at Los Alamos. “We have been working to develop new lasing media, using chemically synthesized quantum dots, although it had been widely believed that quantum dot lasing with electrical stimulation is simply impossible,” he said. “By using our specially designed dots, we can avoid energy losses created by Auger recombination.”

New lasers, made more efficiently

These results demonstrate the feasibility of a new generation of highly flexible, electrically pumped lasers processible from solutions that can complement or even eventually displace existing laser diodes fabricated using more complex and costly vacuum-based epitaxial techniques. These prospective devices can enable a variety of applications, from RGB laser modules for displays and projectors, to multi-wavelength micro-lasers for biological and chemical diagnostics.

Designer Dots With No Heat Loss

In the new report published today in Nature Materials, the Los Alamos team demonstrates that using their “designer” quantum dots, they can achieve light amplification in a nanocrystal solid with direct-current electrical pumping. The key property of the novel quantum dots, underlining the success of the conducted study, is a carefully engineered particle interior in which the material’s composition is continuously varied along a radial direction. This approach eliminates sharp steps in the atomic composition which would normally trigger Auger recombination. As a result, the engineered quantum dots feature nearly complete suppression of Auger effect’s heat loss, and this allows for redirecting the energy released by the electrical current into the light-emission channel instead of wasteful heat.

The Los Alamos nanotechnology team originally discovered the lasing effect in semiconductor nanocrystals in 2000. In these proof-of-principle experiments, reported in the journal Science (http://science.sciencemag.org/content/290/5490/314), the quantum dots were stimulated with very short (femtosecond) laser pulses used to outcompete optical gain decay caused by  the Auger process. Short optical gain lifetimes create an especially serious problem in the case of electrical pumping, which is an inherently slow process as electrons and holes are injected into the quantum dot one-by-one.

Staying focused

Another important element of this work is a special “current-focusing” device architecture which allows the high current densities necessary for achieving optical gain.  The method used by Los Alamos researchers was to taper one of the charge-injection electrodes, limitingthe size of the current-conducting area to less than 100 microns. Using this strategy, they were able to produce current concentration sufficient to reach the regime of light amplification without damaging either the dots or the injection layers.

Publication: Jaehoon Lim, Young-Shin Park, and Victor I. Klimov, Optical Gain in Colloidal Quantum Dots Achieved with Direct-Current Electrical Pumping, Nature Materials, https://www.nature.com/articles/nmat5011

Project members:  Jaehoon Lim (Postdoctoral Research Associate), Young-Shin Park (Guest Scientist, UNM), Victor I. Klimov (Laboratory Fellow, Project Leader)

Acknowledgements: Spectroscopic studies and optical-gain and lasing modelling were funded by the U.S Department of Energy Office of Science. The work on the quantum dot synthesis and device fabrication was supported by the Laboratory Directed Research and Development program at Los Alamos National Laboratory.

About Los Alamos National Laboratory (www.lanl.gov)

Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, BWX Technologies, Inc. and URSCorporation for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health and global security concerns.

 

 

X
X
X
  • Filters

  • × Clear Filters

Beta of Neurodata Without Borders Software Now Available

Neuroscientists can now explore a beta version of the new Neurodata Without Borders: Neurophysiology (NWB:N 2.0) software and offer input to developers before it is fully released next year.

Scientists Discover Path to Improving Game-Changing Battery Electrode

Researchers from Stanford University, two Department of Energy national labs and the battery manufacturer Samsung created a comprehensive picture of how the same chemical processes that give cathodes their high capacity are also linked to changes in atomic structure that sap performance.

ESnet's Petascale DTN Project Speeds up Data Transfers between Leading HPC Centers

A new Petascale Data Transfer Node project aims to to achieve regular disk-to-disk, end-to-end transfer rates of one petabyte per week between major supercomputing facilities, which translates to achievable throughput rates of about 15 Gbps on real world science data sets.

Underappreciated Microbes Now Get Credit for Holding Down Two Jobs in Soil

Soil microbes work as both decomposers and synthesizers of carbon compounds in soil, offering new answers with impacts to crops and eco-health.

Energy, Economy, and the Earth: The Benefits of Creating Feedback Loops

Scientists reduce uncertainties in future climate prediction by directly coupling an energy-economy model to an Earth system model.

How Grasslands Regulate Their Productivity in Response to Droughts

Scientists show that grasslands are more sensitive to changes in the amount of moisture in the air than to changes in precipitation.

Building Confidence in Hydrologic Models

Scientists evaluate seven hydrologic models to understand how each model agrees and differs.

New Research Shows Hydropower Dams Can Be Managed Without an All-or-Nothing Choice Between Energy and Food

Nearly 100 hydropower dams are planned for construction along tributaries off the Mekong River's 2,700-mile stretch. In Science Magazine, researchers present a mathematical formula to balance power generation needs with needs of fisheries downstream.

El Nino and Liquid Water Clouds Contribute to Antarctic Melt in 2015-2016

Atmospheric Radiation Measurement (ARM) observations provide clues on atmospheric contributions to an Antarctic melt event.

Designer Yeast Consumes Plant Matter and Spits Out Fatty Alcohols for Detergents and Biofuels

Highest concentration and yield of valuable chemicals reported in industrial yeast Saccharomyces cerevisiae.


  • Filters

  • × Clear Filters

Stewart Prager Honored with FPA Distinguished Career Award

Announcement of Fusion Power Associates career award for Stewart Prager

WVU Physicists Among Collaborators Granted $7 Million to Form U.S. Department of Energy Center of Excellence

Scientists pause each afternoon at Kirtland Air Force Base in Sandia National Laboratories in Albuquerque, New Mexico, awaiting the daily lightning flash and unmistakable floor jolt that accompanies a Z shot

US Dept. Of Energy Grant to Advance Combined Heat and Power Systems in the Midwest

The University of Illinois at Chicago has received a five-year, $4.2 million grant from the U.S. Department of Energy to help industrial, commercial, institutional and utility entities evaluate and install highly efficient combined heat and power (CHP) technologies.CHP, also known as cogeneration, is a single system that produces both thermal energy and electricity.

Applications Open: ECS Toyota Young Investigator Fellowship 2018-2019

ECS, in a continued partnership with the Toyota Research Institute of North America (TRINA), a division of Toyota Motor Engineering & Manufacturing North America, Inc. (TEMA), is requesting proposals from young professors and scholars pursuing innovative electrochemical research in green energy technology.

Successful Startup Founder to Lead Entrepreneurship Program at Argonne

John Carlisle has been named the director of Chain Reaction Innovations (CRI), a program aimed at accelerating job creation through innovation, based at the U.S. Department of Energy's Argonne National Laboratory.

Department of Energy Supports Argonne Nuclear Technologies

This fall, U.S. Department of Energy Secretary Rick Perry announced nearly $4.7 million in funding for the department's Argonne National Laboratory across 16 projects in three divisions. Four of those TCF awards, representing more than $1 million in funds, are slated for Argonne's Nuclear Engineering division.

Southern Research Develops Gasifier Technology to Unlock Coal's Potential

Southern Research has been selected to receive nearly $1.7 million in U.S. Department of Energy funding to develop a new, cost-efficient gasifier capable of converting low-grade coal into synthesis gas (syngas) that can be used in a number of applications.

CEBAF Begins Operations following Upgrade Completion

The world's most advanced particle accelerator for investigating the quark structure of matter is gearing up to begin its first experiments following official completion of an upgrade to triple its original design energy. The Continuous Electron Beam Accelerator Facility (CEBAF) at the Department of Energy's Thomas Jefferson National Accelerator Facility is now back online and ramping up for the start of experiments.

Chory and Walter Awarded Breakthrough Prizes

HHMI Investigators Joanne Chory and Peter Walter are among five scientists honored for transformative advances toward understanding living systems and extending human life.

Shantenu Jha Named Chair of Brookhaven Lab's Center for Data-Driven Discovery

Jha--a computational scientist who holds a joint appointment as an associate professor at Rutgers University--will lead a center that provides the focal point for data science research and development.


  • Filters

  • × Clear Filters

Underappreciated Microbes Now Get Credit for Holding Down Two Jobs in Soil

Soil microbes work as both decomposers and synthesizers of carbon compounds in soil, offering new answers with impacts to crops and eco-health.

Energy, Economy, and the Earth: The Benefits of Creating Feedback Loops

Scientists reduce uncertainties in future climate prediction by directly coupling an energy-economy model to an Earth system model.

How Grasslands Regulate Their Productivity in Response to Droughts

Scientists show that grasslands are more sensitive to changes in the amount of moisture in the air than to changes in precipitation.

Building Confidence in Hydrologic Models

Scientists evaluate seven hydrologic models to understand how each model agrees and differs.

El Nino and Liquid Water Clouds Contribute to Antarctic Melt in 2015-2016

Atmospheric Radiation Measurement (ARM) observations provide clues on atmospheric contributions to an Antarctic melt event.

Designer Yeast Consumes Plant Matter and Spits Out Fatty Alcohols for Detergents and Biofuels

Highest concentration and yield of valuable chemicals reported in industrial yeast Saccharomyces cerevisiae.

Making Polymer Chemistry Click

Scientists unlock the key to efficiently make a new class of engineering polymers.

Photosynthesis without Cells: Turning Light into Fuel

An entirely human-made architecture produces hydrogen fuel using light, shows promise for transmitting energy in numerous applications.

Craters on Graphene: Electrons Impact

Novel defect control in graphene enables direct imaging of trapped electrons that follow Einstein's rules.

A Molecular Zipper for Efficient Gas Separation

Metal-organic frameworks with chains of iron centers adsorb and release carbon monoxide with very little energy input.


Spotlight

Tuesday October 03, 2017, 01:05 PM

Stairway to Science

Argonne National Laboratory

Thursday September 28, 2017, 12:05 PM

After-School Energy Rush

Argonne National Laboratory

Thursday September 28, 2017, 10:05 AM

Bringing Diversity Into Computational Science Through Student Outreach

Brookhaven National Laboratory

Thursday September 21, 2017, 03:05 PM

From Science to Finance: SLAC Summer Interns Forge New Paths in STEM

SLAC National Accelerator Laboratory

Thursday September 07, 2017, 02:05 PM

Students Discuss 'Cosmic Opportunities' at 45th Annual SLAC Summer Institute

SLAC National Accelerator Laboratory

Thursday August 31, 2017, 05:05 PM

Binghamton University Opens $70 Million Smart Energy Building

Binghamton University, State University of New York

Wednesday August 23, 2017, 05:05 PM

Widening Horizons for High Schoolers with Code

Argonne National Laboratory

Saturday May 20, 2017, 12:05 PM

Rensselaer Polytechnic Institute Graduates Urged to Embrace Change at 211th Commencement

Rensselaer Polytechnic Institute (RPI)

Monday May 15, 2017, 01:05 PM

ORNL, University of Tennessee Launch New Doctoral Program in Data Science

Oak Ridge National Laboratory

Friday April 07, 2017, 11:05 AM

Champions in Science: Profile of Jonathan Kirzner

Department of Energy, Office of Science

Wednesday April 05, 2017, 12:05 PM

High-Schooler Solves College-Level Security Puzzle From Argonne, Sparks Interest in Career

Argonne National Laboratory

Tuesday March 28, 2017, 12:05 PM

Champions in Science: Profile of Jenica Jacobi

Department of Energy, Office of Science

Friday March 24, 2017, 10:40 AM

Great Neck South High School Wins Regional Science Bowl at Brookhaven Lab

Brookhaven National Laboratory

Wednesday February 15, 2017, 04:05 PM

Middle Schoolers Test Their Knowledge at Science Bowl Competition

Argonne National Laboratory

Friday January 27, 2017, 04:00 PM

Haslam Visits ORNL to Highlight State's Role in Discovering Tennessine

Oak Ridge National Laboratory

Tuesday November 08, 2016, 12:05 PM

Internship Program Helps Foster Development of Future Nuclear Scientists

Oak Ridge National Laboratory

Friday May 13, 2016, 04:05 PM

More Than 12,000 Explore Jefferson Lab During April 30 Open House

Thomas Jefferson National Accelerator Facility

Monday April 25, 2016, 05:05 PM

Giving Back to National Science Bowl

Ames Laboratory

Friday March 25, 2016, 12:05 PM

NMSU Undergrad Tackles 3D Particle Scattering Animations After Receiving JSA Research Assistantship

Thomas Jefferson National Accelerator Facility

Tuesday February 02, 2016, 10:05 AM

Shannon Greco: A Self-Described "STEM Education Zealot"

Princeton Plasma Physics Laboratory

Monday November 16, 2015, 04:05 PM

Rare Earths for Life: An 85th Birthday Visit with Mr. Rare Earth

Ames Laboratory

Tuesday October 20, 2015, 01:05 PM

Meet Robert Palomino: 'Give Everything a Shot!'

Brookhaven National Laboratory

Tuesday April 22, 2014, 11:30 AM

University of Utah Makes Solar Accessible

University of Utah

Wednesday March 06, 2013, 03:40 PM

Student Innovator at Rensselaer Polytechnic Institute Seeks Brighter, Smarter, and More Efficient LEDs

Rensselaer Polytechnic Institute (RPI)

Friday November 16, 2012, 10:00 AM

Texas Tech Energy Commerce Students, Community Light up Tent City

Texas Tech University

Wednesday November 23, 2011, 10:45 AM

Don't Get 'Frosted' Over Heating Your Home This Winter

Temple University

Wednesday July 06, 2011, 06:00 PM

New Research Center To Tackle Critical Challenges Related to Aircraft Design, Wind Energy, Smart Buildings

Rensselaer Polytechnic Institute (RPI)

Friday April 22, 2011, 09:00 AM

First Polymer Solar-Thermal Device Heats Home, Saves Money

Wake Forest University

Friday April 15, 2011, 12:25 PM

Like Superman, American University Will Get Its Energy from the Sun

American University

Thursday February 10, 2011, 05:00 PM

ARRA Grant to Help Fund Seminary Building Green Roof

University of Chicago

Tuesday December 07, 2010, 05:00 PM

UC San Diego Installing 2.8 Megawatt Fuel Cell to Anchor Energy Innovation Park

University of California San Diego

Monday November 01, 2010, 12:50 PM

Rensselaer Smart Lighting Engineering Research Center Announces First Deployment of New Technology on Campus

Rensselaer Polytechnic Institute (RPI)

Friday September 10, 2010, 12:40 PM

Ithaca College Will Host Regional Clean Energy Summit

Ithaca College

Tuesday July 27, 2010, 10:30 AM

Texas Governor Announces $8.4 Million Award to Create Renewable Energy Institute

Texas Tech University

Friday May 07, 2010, 04:20 PM

Creighton University to Offer New Alternative Energy Program

Creighton University

Wednesday May 05, 2010, 09:30 AM

National Engineering Program Seeks Subject Matter Experts in Energy

JETS Junior Engineering Technical Society

Wednesday April 21, 2010, 12:30 PM

Students Using Solar Power To Create Sustainable Solutions for Haiti, Peru

Rensselaer Polytechnic Institute (RPI)

Wednesday March 03, 2010, 07:00 PM

Helping Hydrogen: Student Inventor Tackles Challenge of Hydrogen Storage

Rensselaer Polytechnic Institute (RPI)

Thursday February 04, 2010, 02:00 PM

Turning Exercise into Electricity

Furman University

Thursday November 12, 2009, 12:45 PM

Campus Leaders Showing the Way to a Sustainable, Clean Energy Future

National Wildlife Federation (NWF)

Tuesday November 03, 2009, 04:20 PM

Furman University Receives $2.5 Million DOE Grant for Geothermal Project

Furman University

Thursday September 17, 2009, 02:45 PM

Could Sorghum Become a Significant Alternative Fuel Source?

Salisbury University

Wednesday September 16, 2009, 11:15 AM

Students Navigating the Hudson River With Hydrogen Fuel Cells

Rensselaer Polytechnic Institute (RPI)

Wednesday September 16, 2009, 10:00 AM

College Presidents Flock to D.C., Urge Senate to Pass Clean Energy Bill

National Wildlife Federation (NWF)

Wednesday July 01, 2009, 04:15 PM

Northeastern Announces New Professional Master's in Energy Systems

Northeastern University

Friday October 12, 2007, 09:35 AM

Kansas Rural Schools To Receive Wind Turbines

Kansas State University

Thursday August 17, 2006, 05:30 PM

High Gas Prices Here to Stay, Says Engineering Professor

Rowan University





Showing results

0-4 Of 2215