Bridgelux demonstrates silicon substrate LED that produces 135 lumens per watt

March 9, 2011 by Katie Gatto

(PhysOrg.com) -- Silicon substrate LED's are cool, but you won't find them in your TV, or in the headlights of your car. They simply do not throw off enough light to be used in commercial applications. Or, at least they did not used to be able to.

Bridgelux Inc., a California-based developer of semiconductor technology and solid-state lighting, has demonstrated a silicon substrate LED with a light output of 135 lumens per watt. The company believes that this is the first time that anyone has created "commercial grade" performance from a silicon substrate LED.

The performance of 135 lumen per watt came to fruition by using a single 1.5-mm diameter LED that is operated at 350-mA. The LED's have a color correlated temperature (CCT) of 4730K. In order to function the LEDs require a 2.9-V at 350-mA and less than 3.25-V at 1-A.

Instead of using the more commonly found sapphire or silicon carbide substrates to create the epitaxial wafers that are used to create the LED, Bridgelux decided to use the less expensive to produce, by growing, gallium nitride on low-cost silicon wafers. These grown wafers come in 150-, 200- and 300-mm diameters that can, according to Bridgelux, deliver a 75 percent improvement in cost.

Products based on this technology are at least two to three years to come to market. Some of the potential applications for this technology include commercial and office lighting, residential lighting applications, and retrofit lamps that the company hopes will convert to the solid state lighting. No word as to any specifics as to when you can expect to buy a GaN-on-Silicon based LED lamp.

- Tweet
- PHYSorg.com on Twitter

- Reddit
- Delicious
- Yahoo! bookmarks
- RSS
- QR code

view popular send feedback to editors

4.8 /5 (16 votes)

Move the slider to adjust rank threshold, so that you can hide some of the comments.

Display comments: newest first

apex01
Mar 09, 2011

Rank: 1.7 / 5 (6)

This is great but i though LED lights contained lead. They're too dangerous!

http://www.physor...-of.html

jscroft
Mar 09, 2011

Rank: 4.2 / 5 (6)

Not as dangerous as CFLs.

that_guy
Mar 09, 2011

Rank: not rated yet

This is great but i though LED lights contained lead. They're too dangerous!

http://www.physor...-of.html

Not as dangerous as CFLs.

ahhh you beat me to the punch line.

jscroft
Mar 09, 2011

Rank: 1 / 5 (1)

Yah well Congress is beating all of us. Right. Down.

TheQuietMan
Mar 09, 2011

Rank: 5 / 5 (4)

LEDs are encapsulated, which removes any risk. Otherwise the gallium arsenide (as in arsenic) used in most modern LEDs would be in our ground water by now.

A little ignorance goes a long ways.

ormondotvos
Mar 09, 2011

Rank: 5 / 5 (6)

We are being trained to ask fearful stupid questions about everything, but with no intent to learn the answer or the context.

mrwolfe
Mar 09, 2011

Rank: 3.7 / 5 (3)

@apex01
The article you referenced should never have been published by physorg. It is sensationalist rubbish. LED's are made of silicon carbide, aluminium and gallium with trace amounts of arsenic, indium and phosphorus as dopants, but no lead (Pb). The pins are made of copper with tin plating, and the whole thing is encapsulated in polyester or epoxy resin. Electronic manufacturers have been working for over a decade to remove Pb from electronic components in order to comply with RoHS (Restriction of Hazardous Substances)legislation in the European Union. Today, most electronic components are RoHS compliant and therefore contain less han 1000ppm of Pb.

robbor
Mar 09, 2011

Rank: not rated yet

135 lumens, how does this compare to the brightness of a 60 watt incandescent bulb?

apex01
Mar 09, 2011

Rank: not rated yet

Sorry everybody, i was being sarcastic.

mrwolfe
Mar 09, 2011

Rank: not rated yet

Yeah, just realised that.

@robbor, It's not so much brightness as efficiency, or more accurately, efficacy. A 60W tungsten bulb has an efficacy of about 13 lm/W, a halogen has about 25 lm/w and a spiral fluorescent comes in at around 115 lm/W. Brightness will depend onthe number of watts you put in! So, at 1A this LED uses 3.25W and puts out about the same amount of light as a 35W bulb.

antialias
Mar 10, 2011

Rank: 1 / 5 (1)

Minor niggle: Put 1A through a LED and it'll burn out. That's why the LED lights you can buy for home use are always clusters of LEDs

Eikka
Mar 10, 2011

Rank: 5 / 5 (1)

Of course, no mention of the CRI or anything related to the quality of light it produces.

Which is the major problem of LEDs. Non-continuous spectrum that is even worse than CFL's.

antialias
Mar 10, 2011

Rank: 5 / 5 (2)

Depends on where you use it. E.g. headlights for cars don't need a continuous spectrum. Mixing various types of LEDs can give you a (near) continuous spectrum fof applications in your home.

electric
Mar 10, 2011

Rank: 5 / 5 (2)

@antialias

1W LEDs are commonly rated at 700mA. 5W LEDs are rated at even more. There are certainly LEDs that will easily handle 1A continuous. Check out Luxeons or Cree Xlamps

Eikka
Mar 10, 2011

Rank: not rated yet

Depends on where you use it. E.g. headlights for cars don't need a continuous spectrum. Mixing various types of LEDs can give you a (near) continuous spectrum fof applications in your home.

Problem is, will the luminous efficacy remain at 135 lm/W when you introduce more colors?

There's a certain relation between lumious efficacy and color quality. If you have 1 Watt of light, and you have to make the most lumens out of it, you have to center the output at around 490 and 570 nanometers, or monochromatic blue and yellow light. Yellow light is picked up by both red and green sensitive cells in the eye, so you get red green and blue sensations which makes the light look white, but the CRI will be absolutely horrible. Anything viewed under that light will look strange.

So, there's two ways of getting more lumens out of a LED. Either you make it more efficient, or you make the quality of light worse. Guess which one is easier to do?

antialias
Mar 10, 2011

Rank: not rated yet

There's several options of changing the frequency spectrum (varying from the costly to the inefficient). Any such transformation will detract from the 135 lm/W figure. However any other light source has the same problems (except old-school filament bulbs, but their efficiency is so low that they are still MUCH worse)

Upping the lm/W just tells you that even after employing any of these filter/frequency shifts you'll still have more lm/W as before. Certainly more than 13m/W

Moebius
Mar 10, 2011

Rank: not rated yet

The figure of 135 lumens per watt is meaningless without comparison and I am too lazy to look it up, it should have been in the article's next sentence. The article is near worthless without this info and/or research. Another poorly written article.

3432682
Mar 10, 2011

Rank: not rated yet

An incandescent 100w bulb produces 1750 lumens, or 17.5 lumens per watt. It would take 13 watts' worth of this 135-lumens-per-watt device to duplicate a standard 100w incandescent. That's about 8 times more efficient. That's about equal to other LEDs. What we need is a nice cheap price. LEDs are terribly expensive compared to incandescent.

Eikka
Mar 14, 2011

Rank: not rated yet

I use halogen bulbs. They're about twice as efficient as regular bulbs, last twice as long, and produce a continuous spectrum of light by nature.

If you want to check out the spectrum of light your lamps produce, take a pressed DVD, split it in half and carefully peel the silver layer off. The track pattern embedded in the clear plastic works as a diffraction grating that allows you to split the spectrum of light into bands. With a digital camera and a roll of toilet paper, you can then build a spectrograph.

For example, the so called daylight CFLs give you a spectrum that is exactly the same as regular soft whites, but they have a second bright blue spike. It's nowhere near daylight, it's simply more blue.

EWH
May 07, 2011

Rank: not rated yet

White LEDs do not use RGB components, they use a blue, violet or UV LED to excite a mix of phosphors. White LEDs' color accuracy is similar to fluorescents, with a strong peak in the blue and varying quality in the rest of the spectrum depending on the quality of the phosphors used.

Specifying a color temperature for phosphor lighting is misleading since not it does not emit a thermal spectrum. CRI is a more important measure of the quality of the light, with anything much less than 95 being noticeably inferior to incandescent lights.

lengould100
May 09, 2011

Rank: not rated yet

Can anyone say what the theoretical limit of "Visible Lumens per Watt" is irrespecitive of technology, assuming colour were not important. e.g. what's the pure energy content of 100 Lumens of light?

lengould100
May 09, 2011

Rank: not rated yet

Ok found it.

http://en.wikiped...efficacy

As I thought I knew, wasn't quite sure. See from chart 2/3rd way down, no LED's have ever gotten close the the "wall plug efficiency" of common flourecents or sodium lamps.

8.7 W LED screw base lamp (120 V) - 10.1 to 13.6%
Compact Flourescent - 15 to 18%
High pressure sodium lamp - 12 to 22%
Low pressure sodium lamp - 15 to 29%

Agreed, Sodium lamps' colour (orange) is a problem indors, but even flourescents are presently far more efficient than any LED's presently available.

Present references to dispute.

Rank

4.8 /5 (16 votes)

more news

Bridgelux demonstrates silicon substrate LED that produces 135 lumens per watt

Filter

IMEC, AIXTRON set important step towards low-cost GaN power devices

Imec reports record efficiencies for large-area epitaxial thin-film silicon solar cells

Low-cost LEDs to slash household electric bills

Cree Launches XLamp LED Product Line

More news stories

SpotterRF debuts Radar Backpack Kit (w/ Video)

Probability of contamination from severe nuclear reactor accidents is higher than expected: study

Delphi gasoline-injection engine technique rivals hybrid's edge

HyperSolar shows dirty water no barrier to power world

Tesla to launch electric sedan in US on June 22

Dell tablet leak: 10.1-inch display, two-battery choice

Scientist: Evolution debate will soon be history

SpaceX capsule has 'new car' smell, astronauts say (Update)

Thousands of shellfish found dead in Peru

Keep food safety in mind this memorial day weekend

Astronomers seize last chance in lifetime for Venus Transit