Subscribe to our free daily newsletters
  Energy News  




Subscribe to our free daily newsletters



ENERGY TECH
Defects in LED diodes that lead to less efficient solid state lighting identified
by Staff Writers
Santa Barbara CA (SPX) Apr 13, 2016


A conceptual illustration of how defects in a crystal lattice might contribute to nonradiative recombination of electrons and holes in LEDs. Image courtesy Peter Allen/UCSB illustration. For a larger version of this image please go here.

Using state-of-the-art theoretical methods, UCSB researchers have identified a specific type of defect in the atomic structure of a light-emitting diode (LED) that results in less efficient performance. The characterization of these point defects could result in the fabrication of even more efficient, longer lasting LED lighting.

"Techniques are available to assess whether such defects are present in the LED materials and they can be used to improve the quality of the material," said materials professor Chris Van de Walle, whose research group carried out the work.

In the world of high-efficiency solid-state lighting, not all LEDs are alike. As the technology is utilized in a more diverse array of applications - including search and rescue, water purification and safety illumination, in addition to their many residential, industrial and decorative uses - reliability and efficiency are top priorities. Performance, in turn, is heavily reliant on the quality of the semiconductor material at the atomic level.

"In an LED, electrons are injected from one side, holes from the other," explained Van de Walle. As they travel across the crystal lattice of the semiconductor - in this case gallium-nitride-based material - the meeting of electrons and holes (the absence of electrons) is what is responsible for the light that is emitted by the diode: As electron meets hole, it transitions to a lower state of energy, releasing a photon along the way.

Occasionally, however, the charge carriers meet and do not emit light, resulting in the so-called Shockley-Read-Hall (SRH) recombination. According to the researchers, the charge carriers are captured at defects in the lattice where they combine, but without emitting light.

The defects identified involve complexes of gallium vacancies with oxygen and hydrogen. "These defects had been previously observed in nitride semiconductors, but until now, their detrimental effects were not understood," explained lead author Cyrus Dreyer, who performed many of the calculations on the paper.

"It was the combination of the intuition that we have developed over many years of studying point defects with these new theoretical capabilities that enabled this breakthrough," said Van de Walle, who credits co-author Audrius Alkauskas with the development of a theoretical formalism necessary to calculate the rate at which defects capture electrons and holes.

The method lends itself to future work identifying other defects and mechanisms by which SRH recombination occurs, said Van de Walle.

"These gallium vacancy complexes are surely not the only defects that are detrimental," he said. "Now that we have the methodology in place, we are actively investigating other potential defects to assess their impact on nonradiative recombination."

The paper has been published as a Featured Article in the April 4 issue of Applied Physics Letters [APL 108, 141101 (2016)], with an accompanying figure on the cover of the journal.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of California - Santa Barbara
Powering The World in the 21st Century at Energy-Daily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
ENERGY TECH
Back to basics with thermoelectric power
Washington DC (SPX) Apr 11, 2016
Many phenomena in physics, though well-known, are not necessarily widely understood. That's the case with thermoelectricity, which harnesses waste heat by coupling heat flux and electric current. However, understanding such phenomena is important in order to leave the door open for discovering novel manifestations of them. Thus, even today physicists working in the area of thermoelectricit ... read more


ENERGY TECH
Study shows best way to reduce energy consumption

US tech giants file brief in favor of Obama 'clean power' plan

Four killed at anti-China power plant protest in Bangladesh

Human impact forms 'striking new pattern' in Earth's global energy flow

ENERGY TECH
Transition of copper-oxide compound studied in fine detail

Back to basics with thermoelectric power

Creation of Jupiter interior, a step towards room temp superconductivity

For rechargeable batteries that crush the competition, crush this material

ENERGY TECH
Scotland generated most of its electricity in 2015 through renewables

RWE making bold moves in Scottish renewables

Wind energy growing, IEA report finds

Momentum building behind U.S. wind energy

ENERGY TECH
287MW Soda Mountain solar project approved in SoCal

Trina Solar supplies 40 MW of Solar Modules to Tegnatia in Turkey

NREL, SLAC scientists pinpoint solar cell manufacturing process

Perovskite solar-cell absorbers improved by giving them a squeeze

ENERGY TECH
Luxembourg offers cash to help close ageing French nuke plant

French nuclear plant could become electric car factory

Four of Japan's NPP operators seeking to reach deal on safety cooperation

Japan's only working nuclear reactors can stay online

ENERGY TECH
Penn chemists lay groundwork for countless new, cleaner uses of methane

Dung, offal make clean gas at Costa Rica slaughterhouse

ORNL invents tougher plastic with 50 percent renewable content

The flexible way to greater energy yield

ENERGY TECH
China launches SJ-10 retrievable space science probe

Has Tiangong 1 gone rogue

China's 1st space lab Tiangong-1 ends data service

China's aim to explore Mars

ENERGY TECH
Paris climate talks cut back on hot air: report

Drought threatens California despite El Nino

In drought-hit central Nicaragua, water 'is like looking for gold'

Climate forecasts may be flawed, says study




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement