Let There Be LED Light

The common incandescent light bulb is a more efficient heater than it is a light source. They convert 90% of electricity into heat, and only 10% into light. Sorry Mr. Edison, but that sucks.

LED lights are much more efficient - ranging from 47% to 64% efficiency, but they have been too expensive to use for general lighting. That is, until some clever folks at Purdue University made a major advance in LED development.

Until now, LED lights for in-home use were 20 times more expensive to produce than conventional or even compact fluorescent light bulbs. LED lights are based on a sapphire-based substrate. Plus, sapphire-based LEDs needed a separate collector to reflect light that would normally be lost.

What's this new advance that could change the way we light our homes?

Sandsleds The Purdue researchers are developing a new technique that uses low-cost silicon wafers to replace the sapphire layer. The metallized silicon substrate has a built-in reflective layer of zirconium nitride that bounces light back out of the LED.

From the Purdue news report:
"Ordinarily, zirconium nitride is unstable in the presence of silicon, meaning it undergoes a chemical reaction that changes its properties. The Purdue researchers solved this problem by placing an insulating layer of aluminum nitride between the silicon substrate and the zirconium nitride. One of the main achievements in this work was placing a barrier on the silicon substrate to keep the zirconium nitride from reacting. Until the advance, engineers had been unable to produce an efficient LED created directly on a silicon substrate with a metallic reflective layer."

I don't know about you, but I'm beginning to see the light. -Leslie Shapiro

Via Purdue University News

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