A team of scientists at the University of Cambridge has found a production method that could lead to cheaper LEDs within a few years.
LED lights are a technology that most EcoGeeks are hoping to see in widespread distribution. LED lights can be even more efficient than compact fluorescent lights, and they don't contain mercury like CFLs do. LEDs also have a much longer lifespan, and can operate for 10 times longer than fluorescents and 100 times longer than incandescents. They're just still a little expensive, up to $100 / bulb.
One problem with producing LEDs is that the substrate typically used for LEDs is sapphire, rather than silicon, which can be used for many other semiconductors. Many LEDs are made from gallium nitride which is grown into crystals at a temperature of around 1000 C (1832 degrees F). Unlike other electronic components, which can be fabricated on a silicon base, gallium nitride shrinks faster than silicon when it cools, which leads to cracking and failure. Sapphire has a rate of shrinkage and cooling that closely matches the LED compounds, which makes it a suitable substrate.
The University of Cambridge team's development is a method to make LEDs incorporating aluminum gallium nitride, which shrinks much more slowly as it cools, and allows the production of LEDs on silicon wafers like other components. "A 15-centimetre silicon wafer costs just $15 and can accommodate 150,000 LEDs making the cost per unit tiny."
With the commercialization of this process, inexpensive LEDs may become available, and a superior alternative for lighting can help save billions of kilowatt hours of electrical demand.
via: New Scientist
written by Chris, February 02, 2009
written by Tim, February 02, 2009
written by Robin Green, February 03, 2009
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