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Gallium: The White Light LED Revolution

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  • Phil Zarrow: This video is for people interested in gallium arsenide. It will cover applications and future uses.
    Dr. Ronald C. Lasky: Phil, here's some gallium. Check it out.
    Phil Zarrow: Hey, it's liquid.
    Dr. Ronald C. Lasky: Gallium melts at about 90 degrees Fahrenheit. We put this in a little hot water to help it speed along the way. It's one of the few elements that, when you mix it with indium and tin, forms an alloy that melts at -2 Fahrenheit. That's about -19 Celsius. It's in competition with mercury as melting below room temperature, and yet it isn't toxic, so it can be used in applications where you need it as liquid.
    What do you know about gallium in the white light LED revolution?
    Phil Zarrow: Not much. Tell me more.
    Dr. Ronald C. Lasky: Quite a long time ago, gallium, and indium, also, by the way, are used to make little integrated circuits that produce light in lasers and LEDs, and we're all familiar with the very common red LED or laser, which came out quite a few years ago now. It took scientists a bit more time to come up with a green laser or LED, and this is actually best for laser pointers, because eyes are most sensitive to green light.
    Some scientists said we would never be able to make a blue LED or a blue laser, and this actually has a little bit of ultraviolet in it. You see it's not very strong until you come over and shine it on my shirt. For my shirt to be attractive to buy, the manufacturers of the cloth like the cloth to be very, very bright. They actually put things in the cloth, fillers, that sunlight will fluoresce, like my laser pointer is. I'm showing this because the blue light is the essence of why white light is possible – white light LED – because red cannot fluoresce colors toward the blue spectrum, and green cannot fluoresce anything also toward the blue. You really need a blue light, which can fluoresce all of the light of the solar spectrum all the way up to red.
    If I have a blue LED, and I coat it with a fluorescing material, it has the power to fluoresce all of the light in the solar spectrum from where it is to red. All of those lights together, of course, give us white.
    Phil Zarrow: I suppose then that the blue LED was the breakthrough that we really needed…
    Dr. Ronald C. Lasky: The blue LED was the breakthrough. Many scientists thought it couldn't be done, and it was done not too long – about 20 years – ago, and the scientists that did it got a Nobel Prize.
    Phil Zarrow: Ron, do you really think white light LEDs are the way of the future? I frankly don't care for the harsh light, and they're expensive.
    Dr. Ronald C. Lasky: It is true. The light is harsh, but they're getting better at it every day, and I think we're going to find, that as time goes on, that they'll get better and better. You know, one of the reasons we like incandescent light, like this incandescent light bulb, is it produces light in the same process the sun does, which is what we're used to. It produces it by heat, but it's very inefficient. This 60-watt light bulb requires 60 watts to produce the 850 lumens.
    Most of us have seen now that fluorescent lights have come on the scene, and they produce 850 lumens for something about 20 watts, but an LED, even the ones today, can produce the same amount of light as a 60-watt bulb with only 9 watts of power, and, I think, with future developments, that will be down in the 6 range. About 1/10 the energy of an incandescent light in an LED, and when you think that 15% of the electricity used in the United States is used for lighting, this is a tremendous improvement that can't be ignored.
    I think we're going to find in 20 years or so that essentially all lights will be LED's.
    Phil Zarrow: That's a major driver. Yeah, I can see that.
    Dr. Ronald C. Lasky: For those interested in more information about gallium and the white light LED revolution, they can go to
    Phil Zarrow: Ron, thank you very much.