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Purdue's Professor Sands and a graduate researcher man the reactor, which produces the first blue LEDs based on a silicon process. The new LEDs promise greater efficiency, longer lifetimes, and much lower costs.  (Source: Purdue University)
Purdue research have developed new production methods which will cut LED lighting costs to about a twentieth of current expenses

The U.S. Department of Energy recently announced a $20M USD "L Prize" for the first solid-state lighting meeting a strict standard of criteria.  While the prize sounded very intriguing, the fact of the matter is that solid-state lighting on the market today falls short of the requirements by a sizable margin.  Furthermore, it is far too expensive to see mass adoption.

However, a new breakthrough in processing from the Purdue University may change all of that.  Researchers at Purdue have developed a technique to manufacture LED solid-state lighting at low cost using metal-coated silicon wafers.

Traditionally, the light-emitting layer of an LED light is a gallium nitride crystal.  In sapphire based LEDs, used for green or blue lighting, mirror-like reflectors are need to reflect and resend emitted light, increasing the efficiency.  Typically, this layer is extremely expensive to produce, part of the reason the current generation of LED lighting costs so much, costing at least 20 times more than conventional incandescent and fluorescent bulbs.  Also, the LEDs are built on sapphire crystals, which provide the color, but are extremely expensive.  The method uses aluminum nitride to provide the tint.

The new LEDs use a layer of zirconium nitride to provide the mirror effect.  Normally, zirconium nitride reacts with silicon, making a silicon process difficult.  However, by isolating the zirconium nitride with a protective layer to prevent reaction, scientists are able to fully deposit the need layers, including the gallium nitride necessary to build a full LED.

Timothy D. Sands, the Basil S. Turner Professor of Materials Engineering and Electrical and Computer Engineering states, "When the LED emits light, some of it goes down and some goes up, and we want the light that goes down to bounce back up so we don't lose it.  One of the main achievements in this work was placing a barrier on the silicon substrate to keep the zirconium nitride from reacting."

With the advance, for the first time the LEDs will be able to be produced on standard silicon wafers.  The new wafers can be made using cheap existing processes.  To deposit the colored layer, reactive sputter deposition is used.  Aluminum is bombarded with positive Argon ions, which send it flying out into the air, reacting with nitrogen gas and being deposited on the silicon.  For the zirconium reflective layer, an identical process is used with zirconium metal in place of aluminum.  The final gallium layer is deposited using organometallic vapor phase epitaxy; a common deposition technique performed using high heat.

The new techniques yield a crystalline structure aligned to the crystalline silicon.  This means that the LEDs are less prone to defects and will perform more efficiently.  Further, by using common techniques costs are dramatically reduced from using more expensive alternative methods like crystal growth on glass using sapphire crystals.

Another advantage is that silicon dissipates heat more effectively than sapphires.  This will reduce damage during operation and lead to longer lifetimes and more reliability.

The new device is extremely promising as it may allow lighting to finally do primarily what it was intended -- make light.  Traditional incandescent bulbs are better heaters than lights, wasting 90 percent of energy as heat.  LEDs currently on the market have efficiencies from 47 to 64 percent of energy converted into light, with the Purdue design expected to fall on the high-end of this range.

With one third of U.S. electricity going to lighting and tremendous lighting-related consumption worldwide, widespread adoption of LED lighting could cut world electric usage by 10 percent.  Says Professor Sands, "If you replaced existing lighting with solid-state lighting, following some reasonable estimates for the penetration of that technology based on economics and other factors, it could reduce the amount of energy we consume for lighting by about one-third.  That represents a 10 percent reduction of electricity consumption and a comparable reduction of related carbon emissions."

Professor Sands expects the process to be commercially adopted and operating within two years.  A final hurdle for it to overcome is a problem with the gallium nitride layer cracking during cooling.  He believes this problem will soon be solved, though, with a bit more research.  He states, "These are engineering issues, not major show stoppers.  The major obstacle was coming up with a substrate based on silicon that also has a reflective surface underneath the epitaxial gallium nitride layer, and we have now solved this problem."

The researchers' findings are reported in this month's edition of the journal Applied Physics Letters, published by the American Institute of Physics. 

The other researchers contributing to the project led by Professor Sands were Jeremy L. Schroeder, David A. Ewoldt, Isaac H. Wildeson, Robert Colby, Patrick R. Cantwell and Vijay Rawat; Eric A. Stach, an associate professor of materials engineering.  The research was funded by the U.S. Department of Energy's solid-state lighting program, which the L Prize is based on.  The project is part of a broader effort by Purdue to perfect white LED lighting, and perhaps take home the L Prize.

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These will be successful if:
By 67STANG on 7/21/2008 12:29:42 PM , Rating: 3
1) They cost the less/the same/very close to CFL's.
2) They put out at least as much light as CFL's.

As they are LED's, they should definately kill CFL's in life and in power consumption. And my favorite: not having to wait 30-60 sec. for the the light to reach full brightness like current CFL's do.

RE: These will be successful if:
By Screwballl on 7/21/2008 1:10:26 PM , Rating: 4
Not sure what brand or type you are using but I have 20-30 of these around my house (equivalent from 40-100W) and they are at full brightness within 1-2 seconds.... these are the cheaper walmart off-brand ones too, not the more expensive sylvania or name brand types...

I wonder if you aren't talking about tube florescent and not the small CFL replacement lightbulbs? Or maybe using them in 20ºF temperatures???

RE: These will be successful if:
By SiliconJon on 7/21/2008 3:43:24 PM , Rating: 2
I have a large variety of CFL's as replacement for my standard bulbs. Many of them take upwards of 20 seconds to reach full brightness, and some of them have squeeling issues. About half work quite well. I would have to go home and take a survey to see which brands are working less than optimally. I probably won't remember to do that.

RE: These will be successful if:
By stromgald30 on 7/21/2008 4:25:54 PM , Rating: 3
I think there are different varieties of CFLs. Some, possibly newer ones, are designed to come on quicker.

I have both and some CFL recessed lighting bulbs. The spot/recessed lighting ones can take up to a minute to get to full brightness. The regular CFLs take 3-10 seconds depending on age, and the "quick-on" ones take like 1-2 seconds max.

RE: These will be successful if:
By daftrok on 7/22/2008 2:42:22 AM , Rating: 3
Dear God all these posts about CFL brightness timing. The only time I would find this annoying is with projectors and projector TVs but not with lights.

RE: These will be successful if:
By lumbergeek on 7/21/2008 11:43:02 PM , Rating: 2
Yes, they are the newer blue-label "Globe" brand they sell at wal-mart. I like them a lot, the light is much more white than the earlier generation yellowish types and they come on very quickly. I replaced all my CCFLs with them. They also come in up to 150w incandescent equivalent using only 40 watts.

RE: These will be successful if:
By FITCamaro on 7/21/08, Rating: -1
RE: These will be successful if:
By Natfly on 7/21/2008 2:19:32 PM , Rating: 4
Its a very common problem, even in brand new CFLs that I have bought I have noticed this.

RE: These will be successful if:
By FITCamaro on 7/21/08, Rating: 0
RE: These will be successful if:
By SiliconJon on 7/21/2008 3:47:08 PM , Rating: 2
I have a five-CFL-bulb lamp in the computer room that when used feels like a nuke effect out of a movie - the brightness goes from fair to sunlight over 10 seconds. It's quite noticeable, but I probably won't freak out from it unless I watch some crazy end of the world movie.

RE: These will be successful if:
By SiliconJon on 7/21/2008 3:53:22 PM , Rating: 2
Sorry, that's a bit of an's only about 3-4 seconds, though the first time it occurred time did slow to a crawl.

By Bruneauinfo on 7/21/2008 3:53:40 PM , Rating: 2
same issue here with all of mine. i have about 15. they all take a while to get to full brightness.

RE: These will be successful if:
By walk2k on 7/21/2008 3:18:33 PM , Rating: 2
CFL I have in my house all reach full brightness instantly, or within a few 1/10th of a second anyway. 3-5 seconds? are these outside in -20F temps??

RE: These will be successful if:
By Spuke on 7/21/2008 4:16:16 PM , Rating: 3
My office CFL takes a few seconds to warm up but my porch lights are at full brightness almost instantly.

RE: These will be successful if:
By kmmatney on 7/21/2008 4:06:41 PM , Rating: 2
A lot of my CFL bulbs can take up to 3 minutes to reach full brightness (and it also states this on the Ge website). I've had these bulbs for 4 years, so they may be older models and things might be better now.

RE: These will be successful if:
By mattclary on 7/21/2008 2:18:59 PM , Rating: 2
The temperature seems to have a big impact. I notice mine take a while to reach full brightness when the house is cold. When it is warm, they are pretty instant.

RE: These will be successful if:
By teldar on 7/22/2008 8:51:25 AM , Rating: 2
The ballast/starter has to warm up for CFL's to reach full brightness. It's normal for them to take some time.
I have a significant number of new ones (sylvania and nlight? as well as GE) and they all take some time to get as bright as they are going to get.

But I still like them quite a bit. I have 3 100watt replacements in a floor lamp in the living room and it puts out over 5000 lumens for 75 watts. To get that out of incandescent, it would be more like 400 watts.

White LEDS
By Curelom on 7/21/2008 1:03:49 PM , Rating: 2
Now if we can get White LEDS that are actually white, not blue-ish.

RE: White LEDS
By FITCamaro on 7/21/2008 1:26:15 PM , Rating: 2
I don't mind the blueish hue. The sky is blue.

RE: White LEDS
By deeznuts on 7/21/2008 1:43:11 PM , Rating: 2
The Sky is blue, but that's due to the atmosphere scattering blue wavelengths. So while the sky is blue, the light that actually reaches you, is short on blue. Unless you look up :)

RE: White LEDS
By FITCamaro on 7/21/2008 2:35:13 PM , Rating: 2
True. But to me the blue is a pleasant tint. But then, I like blue.

I like how my personal opinion on a shade of light gets rated down.

RE: White LEDS
By Spuke on 7/21/2008 4:43:55 PM , Rating: 1
There is no opinion. There is only Zuul.

RE: White LEDS
By glitchc on 7/22/2008 10:32:24 AM , Rating: 2
Human eyes have lower responsivity to higher frequencies in the visual spectrum. The eye has much fewer receptors for blue than it does for green and red.

RE: White LEDS
By Solandri on 7/21/2008 3:15:14 PM , Rating: 2
Sunlight by the time it reaches the Earth's surface has a color temperature of about 5500 K. The European standard for daylight is about 6500 K (bluer) because it factors in light from the blue sky. In shade, the color temperature can reach 7500-8500K (very blue) because the predominant lighting is from the blue sky.

The blue in the sky is mostly from oblique light. The only time you will encounter that light directly is during sunrise and sunset, which is why those are reddish.

RE: White LEDS
By Solandri on 7/21/2008 3:30:18 PM , Rating: 5
1. There is no single "white". Your eyes and brain automatically adjust to a wide variety of lighting conditions, effectively setting an automatic white balance. So a wide variety of light colors can be perceived as white. If there are two different colored lights, which one you perceive as white depends mostly on what you are used to, not which one is actually whiter.

2. Most white LEDs actually emit 6500 K, which is the color of light on a sunny day with blue skies. People just perceive it as bluish because most lights at night are incandescent (around 2000-3000 K). We're used to that dull orange/yellow color and our brains have been wired since childhood to perceive it as white at night. If you use the "bluish" LED in a remote area at night where it's the only visible light (aside from possibly the moon), it will look white. (Moonlight is about 4100K, which while yellower than sunlight, is bluer than incandescent lights.)

3. 2000-3000K incandescent lights are actually pretty bad from a color standpoint. You lose a lot of color detail under those lights. Paradoxically, this is one of the reasons it's popular - the loss of most of the greens and blues hides skin blemishes, giving people a "healthy" golden glow.

4. The effect of having incandescent light ingrained into us since childhood is so strong, that when I installed 5500K daylight spectrum CFLs in my room at work (and noticed a dramatic improvement in my color perception), visitors actually complained about the "unnatural" color of the light.

RE: White LEDS
By mindless1 on 7/21/2008 7:19:48 PM , Rating: 2
What are you implying, that you can't get the hue you want?

You can in fact, any reputable LED manufacturer clearly specs the hue, you can choose less blue if that is what you want.

However, the more blue(ish) it is, the more light it produces because the conversion from blue isn't 100% efficient (base LED die is entirely blue no matter the final resulting hue of a "white" LED).

By qrhetoric on 7/21/2008 12:41:00 PM , Rating: 2
This is fantastic news. Enough new technologies like this, and we may be able to get through another hundred years without running out of oil.

I have a question, if anyone happens to know the answer - is it a problem that all these new lighting technologies have gaps in the spectrum they produce? Our eyes are naturally adapted to sunlight, and I think incandescent comes very close to filling that spectrum naturally. I know that fluorescent bulbs have large gaps, and I don't really know how our brains respond to that. I'm not sure what the gaps are in LEDs.


RE: Fantastic
By foxtrot9 on 7/21/2008 12:46:19 PM , Rating: 2
Any gaps will just not be visible on that color object that the LED is reflecting off of. Otherwise it will not hurt and if there is another light source in the room you should not notice it

RE: Fantastic
By 4play on 7/21/2008 1:28:57 PM , Rating: 2
getting off oil really has nothing to do with lighting...

RE: Fantastic
By livelouddiefast on 7/21/2008 1:42:23 PM , Rating: 2
"enough new technologies"

i believe they were speaking of innovations in all fields, including energy production.

RE: Fantastic
By RandallMoore on 7/22/2008 10:54:25 AM , Rating: 2
Um, what planet do you live on?? The efficiency of lighting has a TREMENDOUS effect on total energy consumption of the world. Where do you think the electricity to power the lights in your house come from? The magical electricity fairy? haha, anyway that you look at it dude, oil controls this entire planet. Food, wages, EVERYTHING. So of course, a theoretical 10% drop in energy consumption for lighting would have a massive impact on the economy. Not calling you an idiot, but you must realize that everything revolves around oil. No exceptions.

RE: Fantastic
By Asbestos on 7/22/2008 1:41:10 PM , Rating: 2
Very little electricity is produced from oil. Nuclear, coal, and natural gas are the primary fuels for electric generation. Welcome to Earth.

RE: Fantastic
By RandallMoore on 7/22/08, Rating: 0
RE: Fantastic
By Solandri on 7/21/2008 3:40:28 PM , Rating: 2
Incandescent lights do a very poor job of mimicking sunlight. They're extraordinarily weak in green and blue. It's just that our eyes and brains are remarkably effective at accommodating for this shortfall.

The spiky nature of LED and balanced fluorescent can be bad, but if you have enough spikes it evens out. Most colored objects will reflect a range of frequencies that are near their color, not just a narrow band. The exceptions are iridescent colors, which rely on scattering a specific frequency of light to generate color.

RE: Fantastic
By MicahK on 7/22/2008 12:53:37 PM , Rating: 2
Sunlight itself has many gaps in its spectra due to absorption by elements in its atmosphere. Check it out:

Theres no way your brain could pick them out tho....

Also if anyone of you has ever picked up white paint from the store, you'd know that theres about 20 different shades of white that look completely white unless you hold a different shade up next to it and compare. Its the same for light, we've just gotten used to the color of incandescent bulbs so they seem like a "natural" white to us...

Actually studies have shown that whiter light (~6500 K) actually improve work performance, alertness, and concentration...

Las Vegas
By Fnoob on 7/21/2008 12:48:16 PM , Rating: 2
Might be interested. Maybe.

Then perhaps they could sell the extra energy they aren't using from the Hoover damn to California. Wonder if 'sin city' could still be seen from 500 miles away if they switch to all LEDs? ;)

RE: Las Vegas
By cubeless on 7/21/2008 1:05:19 PM , Rating: 1
i know every bit helps, but just turning off the lights when u leave a room would do more than this...

RE: Las Vegas
By srue on 7/21/2008 2:02:38 PM , Rating: 4
No reason you can't do both.

RE: Las Vegas
By Schrag4 on 7/22/2008 10:09:03 AM , Rating: 2
If the LED lights come to the market at a lower cost than CFL and produce light that's easy on the eyes, then you're right. If they're more expensive than CFL and (more importantly) if the light looks unnatural, then I find plenty of reason not to do both.

Anytime Now
By UppityMatt on 7/21/2008 1:48:50 PM , Rating: 2
I have a feeling Masher is going to jump in any moment now and calculate the actual savings based on cost. I can get us thinking in the right direction, ill let him do all the number crunching though. I would think that seems these currently cost 20 times more then current lighting, even reducing this cost by 1/20...its still WAY more expensive. Unless these have a lifespan that is at least 20 times longer then current methods (the article only briefly states that
This will reduce damage during operation and lead to longer lifetimes and more reliability.
, but never states what the current lifetime and reliability is). I have to agree seems like we could save >10% of the worlds energy by shutting the dang lights off when we leave the room or by putting more windows in a house.

RE: Anytime Now
By solah13 on 7/21/2008 2:13:16 PM , Rating: 3
I would think that seems these currently cost 20 times more then current lighting, even reducing this cost by 1/20...its still WAY more expensive.

Pretty big difference between "by 1/20" and "to one twentieth"

RE: Anytime Now
By UppityMatt on 7/21/2008 3:21:33 PM , Rating: 2
Yep you are correct, when i read it through the first time i thought it was just 1/20th. Thanks

RE: Anytime Now
By soloman02 on 7/22/2008 2:26:30 PM , Rating: 2
Here you go:
Cree projects XLamp LEDs to maintain an average of 70% lumen maintenance after 50,000 hours, provided the LED junction temperature is maintained at or below 80ºC.

After 50,000 hours of continuous operation, the Xlamp LED's will still provide 70% of the original light output. That translates to 5 years of never being turned off. Most people do not leave a light on for 24 hours at a time, so if you have the light on for 12 hours out of every day, you have effectively doubled the lifespan of the LED to 10 years.

And here is a link to the reliability data for Cree LED's.

Global Warming.
By Spectator on 7/21/08, Rating: 0
RE: Global Warming.
By Master Kenobi on 7/21/2008 2:07:34 PM , Rating: 4
Yes, it was always a running joke among the engineering crowd that if we were ever visited by aliens they would mistake our light bulbs for heating devices that accidently generated light as a byproduct of the process.

RE: Global Warming.
By FITCamaro on 7/21/2008 2:37:35 PM , Rating: 3
Tactical office: "Sir they're powering their heat based weapons!"

Captain: "Shields to full! Destroy their cities!"

RE: Global Warming.
By FITCamaro on 7/21/2008 2:37:57 PM , Rating: 1

By tastyratz on 7/21/2008 1:15:14 PM , Rating: 2
Traditional incandescent bulbs are better heaters than lights, wasting 90 percent of energy as heat. LEDs currently on the market have efficiencies from 47 to 64 percent of energy converted into light

Does anyone know what efficiency cfl bulbs fall under in comparison?
I did some math and came out to approx ~7 times more efficient watt/lumen compared to incandescent based on this chart:

If that's the case it would look like cfl lighting still edges out led efficiency by ~6%.
Major advancement for led lighting definitely - but still need improvement before solid state lighting replaces cfl bulbs or at least becomes financially competitive.

RE: data?
By Solandri on 7/21/2008 3:50:52 PM , Rating: 2
CFLs typically produce the same amount of light as incandescents at 1/4th the wattage.

RE: data?
By mindless1 on 7/21/2008 7:30:43 PM , Rating: 2
Not true, since which one is a single digit percent more efficient is one of the least important factors.

LEDs can have no flicker or less noticable (higher frequency) at a good price-point for the driving circuit.

LEDs last much longer

LEDs' driver circuit lasts much longer than a typical integrated CCFL bulb's circuit.

LEDs go (for all practical purposes) to full brightness instantly, no warm up at all.

LEDs can be used in cold climates.

LEDs are inherantly more rugged for mobile or other mechanically stressful applications.

LEDs can be smaller, but the real beauty of a whole lighting device using them is that since they last so long you don't need to think in terms of a lamp with a screw in bulb anymore, making way for new smaller form factor lighting fixtures where the LEDs are not replaced, rather the whole fixture is many years later when the LEDs or driver fails, or they just age enough that their light output isn't enough for the application any longer.

By HighTech4US on 7/22/2008 8:47:56 AM , Rating: 2
Professor Sands expects the process to be commercially adopted and operating within two years. A final hurdle for it to overcome is a problem with the gallium nitride layer cracking during cooling.

How many of times have we been told about these breakthroughs and told will be available in (pick a date) years have never come to be.

By Schrag4 on 7/22/2008 10:15:08 AM , Rating: 2
Would be fun to see research on all future-tech articles from 5-15 years ago that claimed we would be using a product cheaply by the year 2008 or earlier, and see what percent of them were right. My guess is that it's somewhat low.

But will they be disposable?
By daveG on 7/21/2008 1:51:44 PM , Rating: 3
Success has another caveat: Can we throw them out when broken/worn out? I understand they will last a lot longer but the current gen of cheap flourescents can't be tossed. Nice. Mercury maybe? So the new LEDs are standard silicon, does this mean we can safely throw them in landfills?

Obviously I am no chemist, just concerned.

Look Honey...
By Smartless on 7/21/2008 2:54:30 PM , Rating: 3
Your diamond ring I bought can also generate light too... Nothings too good for you.
(I know its not EXACTLY the same but wouldn't that be great.)

By William Gaatjes on 7/21/2008 3:03:38 PM , Rating: 2
With the advance, for the first time the LEDs will be able to be produced on standard silicon wafers. The new wafers can be made using cheap existing processes.

This is great news. Together with the technique from IBM to use discarded wafers from normal chip producting,this could swing the balance towards the led faster. These wafers are to be used for solar panels according to the article but maybe it is usefull for making leds this way too ?

LED Heat
By animekev on 7/22/2008 1:45:51 PM , Rating: 2
Sound like this should also help greatly with heat pollution; not only will these "bulbs" need less electricity to produce the equivelant lumens, they will make less heat as a by-product. I wouldn't be surprised if widespread adoption would reduce the global warming trend by a small but measurable factor.

By Oroka on 7/22/2008 11:31:29 PM , Rating: 2
So, what this translates to is LED lighting manufactures can make thier wares at a fraction of what they cost now, and sell them to us at twice they cost as traditional LEDs saying they are 'Green' and will last xx% longer.


CFLs are filled with mercury
By jrbloch on 7/23/2008 4:36:35 AM , Rating: 2
When a CFL breaks, mercury gas and powder will contaminate the area. Don't use CFLs for indoor use. Global warming is a hoax anyway. The south pole has record ice, and global 2008 temperatures are below the 100 yr mean. Al Gore is such a nut case. Don't poison your family with CFLs. Wait for affordable LED, it won't take that long to happen.

I had this
By Suntan on 7/23/2008 3:52:34 PM , Rating: 2
...organometallic vapor phase epitaxy

I’ve had this exact process happen to me when one particularly tasty Chipotle went horribly wrong after eating it.


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