Immagine
 Trilingual World Observatory: italiano, english, română. GLOBAL NEWS & more... di Redazione
   
 
\\ Home Page : Articolo
Researchers at the University of California, Santa Barbara, say they've figured out the cause of a problem that's made light-emitting diodes (LEDs) impractical for general lighting purposes.
By Admin (from 16/07/2011 @ 11:00:21, in en - Global Observatory, read 1893 times)

Their work will help engineers develop a new generation of high-performance, energy-efficient lighting that could replace incandescent and fluorescent bulbs.

"Identifying the root cause of the problem is an indispensable first step toward devising solutions," says Chris Van de Walle, a professor in the Materials Department at UC Santa Barbara who heads the research group that carried out the work.

Van de Walle and his colleagues are working to improve the performance of nitride-based LEDs, which are efficient, non-toxic and long-lasting light sources. They investigated a phenomenon referred to as "droop"?the drop in efficiency that occurs in these LEDs when they're operating at the high powers required to illuminate a room. The cause of this decline has been the subject of considerable debate, but the UC Santa Barbara researchers say they've figured out the mechanism responsible for the effect by performing quantum-mechanical calculations.

LED droop, they conclude, can be attributed to Auger recombination, a process that occurs in semiconductors, in which three charge-carriers interact without giving off light. The researchers also discovered that indirect Auger effects, which involve a scattering mechanism, are significant?a finding that accounts for the discrepancy between the observed degree of droop and that predicted by other theoretical studies, which only accounted for direct Auger processes.

In nitride LEDs, "These indirect processes form the dominant contribution to the Auger recombination rate," says Emmanouil Kioupakis, a postdoctoral researcher at UC Santa Barbara and lead author of a paper published online April 19 in Applied Physics Letters. The other authors are Van de Walle, Patrick Rinke, now with the Fritz Haber Institute in Germany, and Kris Delaney, a project scientist at UC Santa Barbara.

LED droop can't be eliminated because Auger effects are intrinsic, but it could be minimized, the researchers say, by using thicker quantum wells in LEDs or growing devices along non-polar or semi-polar growth directions in order to keep carrier density low.

"With Auger recombination now established as the culprit, we can focus on creative approaches to suppress or circumvent this loss mechanism," Van de Walle says.
 
Source: PhysOrg

Articolo Articolo  Storico Storico Stampa Stampa  Share
Cannabis seeds, Autoflowering seeds, Greenhouse, Sweet Seeds, Dutch Passion
comments powered by Disqus
 
Nessun commento trovato. No comments found. Nici un comentariu găsit.

Anti-Spam: dial the numbers CAPTCHA
Text (max 5000 characters)
Nome - Name - Nume
Link ( OPTIONAL - visible on the site - NOT a must )


Disclaimer
Tuo commento sarŕ visibile dopo la moderazione. - Your comment will be visible after the moderation. - Comentariul tău va fi vizibil după moderare.
Ci sono 1476 persone collegate

< novembre 2019 >
L
M
M
G
V
S
D
    
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
 
             

Titolo
en - Global Observatory (605)
en - Science and Society (594)
en - Video Alert (346)
it - Osservatorio Globale (503)
it - Scienze e Societa (555)
it - Video Alerta (132)
ro - Observator Global (399)
ro - Stiinta si Societate (467)
ro - TV Network (149)
z - Games Giochi Jocuri (68)

Catalogati per mese - Filed by month - Arhivate pe luni:

Gli interventi piů cliccati

Ultimi commenti - Last comments - Ultimele comentarii:
Hi, it's Nathan!Pretty much everyone is using voice search with their Siri/Google/Alexa to ask for services and products now, and next year, it'll be EVERYONE of your customers. Imagine what you are ...
15/01/2019 @ 17:58:25
By Nathan
Now Colorado is one love, I'm already packing suitcases;)
14/01/2018 @ 16:07:36
By Napasechnik
Nice read, I just passed this onto a friend who was doing some research on that. And he just bought me lunch since I found it for him smile So let me rephrase that Thank you for lunch! Whenever you ha...
21/11/2016 @ 09:41:39
By Anonimo


Titolo

Latest NEWS @
www.TurismoAssociati.it

Non-Hodgkin lymphoma cured by CANNABIS. The video of Stan and Barb Rutner.

Dr. Joycelyn Elders, U.S. surgeon general: Myths About Medical Marijuana in The Providence Journal, 2004.

Marihuana vindeca CANCERUL: marturii despre uleiul de cocos si canabis.

Yahoo Incorporated Mail. My account recovery information is incorrect. The Password Helper says my password can't be reset online. "First time signing in here?" message.

All information in a video about Donatio Mortis Causa and The Venus Project

What is TOR browser?

Trade deal hopes, surging health stocks power Wall Street to highs

Bolivia blames Cubans for stirring unrest, ousts Venezuelan officials

Trump ex-aide Gates faces December 17 sentencing after being star witness

Trump grants pardons to Army officers in war crimes cases

U.S. FAA regulator head tells team to 'take whatever time needed' on 737 MAX

Twitter tightens bans on political ads and causes ahead of 2020 U.S. election

Ultimele articole - Antena3.roHOROSCOP. Sfatul Arhanghelului Mihail pentru zodii 15 noiembrie. Leii primesc raspunsuri, Scorpionii trebuie sa se simta în siguran?a

HOROSCOP 16 NOIEMBRIE. Racii trebuie sa faca un pas în spate, Varsatorii petrec timp cu familia

CALENDAR ORTODOX 16 NOIEMBRIE. Ce sfânt este sarbatorit astazi?

Oamenii dintr-un apartament din zona Pipera auzeau zi ?i noapte zgomote ciudate din spatele aparatului de aer condi?ionat de afara. Într-o zi, au decis sa se uite sa vada ce e ?i au încremenit: Erau peste 50! (VIDEO)

Monica era în troleul 69, când a auzit o femeie vorbind lânga ea. Când ?i-a dat seama cine este aceasta, a crezut ca le?ina: O Doamne, cum sa vezi a?a ceva mereu într-un troleu?

Doi poli?i?ti, rani?i într-un accident rutier în timp ce urmareau o ma?ina





16/11/2019 @ 02:04:47
script eseguito in 919 ms