Don't worry, you needn't fear seeing your neighborhood turned into a tricked out light display with gimmicky LEDs (the same can't be said about your neighbors' PCs), but inside those homes, incandescent and compact fluorescent lightbulbs might be on their way to becoming extinct. Helping put them on the endangered tech list are researchers at Purdue University who claim to have found a way to create low-cost LEDs.

Light-emitting diodes are said to be about four times more efficient than your standard lightbulb, they're easier on the environment, and with a lifespan perhaps as long as 15 years, LEDs seem destined to light up your living room. One thing preventing them from doing that are the high manufacturing costs, driven in large part by a costly sapphire substrate used to make LEDs. Compared to conventional incandescent and fluorescent lightbulbs, LED replacements would be at least 20 times more expensive.

It would take a major breakthrough in reducing the cost of "solid state lighting" to make LEDs a viable alternative to traditional lighting, and an engineering team at Purdue think they've made one. Instead of using a sapphire substrate, the Purdue researchers have developed a technique to create LEDs on low-cost, metal-coated silicon wafers. While sapphire-based LEDs require a separate mirror-like collector to reflect light, this new silicon substrate comes with a built-in reflective layer of zirconium nitride.

"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," said Timothy D. Sands, the Basil S. Turner Professor of Materials Engineering and Electrical and Computer Engineering.

A news release posted on Purdue's website breaks the process down into greater detail, the final result of which means that LED lights could be on the market within two years. But first, researchers will have to find a way to reduce defects in the devices and prevent the gallium nitride layer from cracking as the silicon wafer cools down. When they do, get ready to toss out your old bulbs.

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