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Community => Bar Sport => Topic started by: Big Oil on May 04, 2011, 11:45 pm

Title: The humble LED still a hot area of physics research
Post by: Big Oil on May 04, 2011, 11:45 pm
http://newweb.nersc.gov/news-publications/science-news/2011/led-lighting-comes-out-of-the-dark (http://newweb.nersc.gov/news-publications/science-news/2011/led-lighting-comes-out-of-the-dark)

Today I learned: Physicists are still discovering new things about the LED, and are trying to build better ones. 

There are ongoing debates about its properties: 

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The exact cause of drooping photon production in nitride-based LEDs has been hotly debated between two main camps: One thinks the electrons become so energized that they overflow the quantum well and escape. The other camp, to which Van de Walle's group belongs, thinks that the energy created by an electron/hole combination -- physicists call it "recombination" -- is being quietly swallowed by another charge carrier (a hole or an electron) inside the quantum well. This phenomenon is called Auger recombination.


The results of a recent experiment show that neither group was exactly right, but 'recombination' was the main culprit.
Title: Re: The humble LED still a hot area of physics research
Post by: westfw on May 05, 2011, 03:22 am
LEDs are a VERY hot topic these days, as high-power LEDs bid to replace more conventional forms of lighting (incandescent, fluorescent, etc.)  There are magazines and technical conferences dedicated to LEDs...
(I would say that most of the activity is "above" the level of physics, though.)

Title: Re: The humble LED still a hot area of physics research
Post by: liuzengqiang on May 06, 2011, 09:04 pm
Not to mention organic LEDs :)

Auger recombination. En, I'll read up.

http://en.wikipedia.org/wiki/Carrier_generation_and_recombination#Auger_recombination
Title: Re: The humble LED still a hot area of physics research
Post by: Magician on May 06, 2011, 09:48 pm
I surprised, :
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In the case of blue and green LEDs, the base semiconductor material is gallium nitride, so the entire family is called nitride-based LEDs.


Since when green led became nitride-based instead of Al-Ga-As?
Title: Re: The humble LED still a hot area of physics research
Post by: westfw on May 07, 2011, 12:33 am
http://members.misty.com/don/ledc.html
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Ultrabright Orange-Red, Orange, Yellow, and Green, InGaAlP
Green LEDs, GaP
High Efficiency Green LEDs, GaAlP
"Pure Green" LEDs, GaP
InGaN (indium gallium nitride) ultrabright blue and green LEDs