Featured Research

from universities, journals, and other organizations

Voiding defects: New technique makes LED lighting more efficient

Date:
January 25, 2011
Source:
North Carolina State University
Summary:
Light-emitting diodes (LEDs) are an increasingly popular technology for use in energy-efficient lighting. Researchers have now developed a new technique that reduces defects in the gallium nitride (GaN) films used to create LEDs, making them more efficient.

The new technique reduces the number of defects in those films by two to three orders of magnitude -- increasing the output of light by a factor of two for a given amount of power.
Credit: Image courtesy of Lukasz Tylec

Light-emitting diodes (LEDs) are an increasingly popular technology for use in energy-efficient lighting. Researchers from North Carolina State University have now developed a new technique that reduces defects in the gallium nitride (GaN) films used to create LEDs, making them more efficient.

Related Articles


LED lighting relies on GaN thin films to create the diode structure that produces light. The new technique reduces the number of defects in those films by two to three orders of magnitude. "This improves the quality of the material that emits light," says Dr. Salah Bedair, a professor of electrical and computer engineering at NC State and co-author, with NC State materials science professor Nadia El-Masry, of a paper describing the research. "So, for a given input of electrical power, the output of light can be increased by a factor of two - which is very big." This is particularly true for low electrical power input and for LEDs emitting in the ultraviolet range.

The researchers started with a GaN film that was two microns, or two millionths of a meter, thick and embedded half of that thickness with large voids - empty spaces that were one to two microns long and 0.25 microns in diameter. The researchers found that defects in the film were drawn to the voids and became trapped - leaving the portions of the film above the voids with far fewer defects.

Defects are slight dislocations in the crystalline structure of the GaN films. These dislocations run through the material until they reach the surface. By placing voids in the film, the researchers effectively placed a "surface" in the middle of the material, preventing the defects from traveling through the rest of the film.

The voids make an impressive difference.

"Without voids, the GaN films have approximately 10[to the 10th power] defects per square centimeter," Bedair says. "With the voids, they have 10[to the 7th power] defects. This technique would add an extra step to the manufacturing process for LEDs, but it would result in higher quality, more efficient LEDs."

The paper, "Embedded voids approach for low defect density in epitaxial GaN films," was published online Jan. 17 by Applied Physics Letters. The paper was co-authored by Bedair; Pavel Frajtag, a Ph.D. student at NC State; Dr. Nadia El-Masry, a professor of material science and engineering at NC State; and Dr. N. Nepal, a former post-doctoral researcher at NC State now working at the Naval Research Laboratory. The research was funded by the U.S. Army Research Office.


Story Source:

The above story is based on materials provided by North Carolina State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. P. Frajtag, N. A. El-Masry, N. Nepal, S. M. Bedair. Embedded voids approach for low defect density in epitaxial GaN films. Applied Physics Letters, 2011; 98 (2): 023115 DOI: 10.1063/1.3540680

Cite This Page:

North Carolina State University. "Voiding defects: New technique makes LED lighting more efficient." ScienceDaily. ScienceDaily, 25 January 2011. <www.sciencedaily.com/releases/2011/01/110125123237.htm>.
North Carolina State University. (2011, January 25). Voiding defects: New technique makes LED lighting more efficient. ScienceDaily. Retrieved January 30, 2015 from www.sciencedaily.com/releases/2011/01/110125123237.htm
North Carolina State University. "Voiding defects: New technique makes LED lighting more efficient." ScienceDaily. www.sciencedaily.com/releases/2011/01/110125123237.htm (accessed January 30, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, January 30, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Tesla 'Insane Mode' Gives Unsuspecting Passengers the Ride of Their Life

Tesla 'Insane Mode' Gives Unsuspecting Passengers the Ride of Their Life

RightThisMinute (Jan. 29, 2015) — If your car has an "Insane Mode" then you know it&apos;s fast. Well, these unsuspecting passengers were in for one insane ride when they hit the button. Tesla cars are awesome. Video provided by RightThisMinute
Powered by NewsLook.com
Now Bill Gates Is 'Concerned' About Artificial Intelligence

Now Bill Gates Is 'Concerned' About Artificial Intelligence

Newsy (Jan. 29, 2015) — Bill Gates joins the list of tech moguls scared of super-intelligent machines. He says more people should be concerned, but why? Video provided by Newsy
Powered by NewsLook.com
Senate Passes Bill for Keystone XL Pipeline

Senate Passes Bill for Keystone XL Pipeline

AP (Jan. 29, 2015) — The Republican-controlled Senate has passed a bipartisan bill approving construction of the Keystone XL oil pipeline. (Jan. 29) Video provided by AP
Powered by NewsLook.com
Two Stunt Pilots Perform Incredibly Close Flyby

Two Stunt Pilots Perform Incredibly Close Flyby

Rumble (Jan. 29, 2015) — Two pilots from &apos;Escuadrilla Argentina de Acrobacia Aιrea&apos; perform an incredibly low altitude flyby stunt during a recent show exhibition in Argentina. Check it out! Video provided by Rumble
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins