The LED lightbulb has loads to recommend it. Compared to the compact fluorescent, it can be twice as efficient, lasts far longer, and is free of mercury. But high prices are holding back sales: A 40-watt-equivalent LED bulb with a good hue starts at around US $20, and 60-W versions retail for far more.

The good news is that this barrier to mass adoption should fall in the next two to three years, thanks to recent developments by the LED maker Bridgelux that should spur the launch of a $5 bulb. This California-based firm plans to slash the price of white emitting chips—which account for up to 70 percent of the cost of this type of bulb—by churning out millions of gallium nitride LEDs on 200-millimeter-diameter silicon wafers.

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3D-Stacked CMOS Takes Moore’s Law to New Heights

When transistors can’t get any smaller, the only direction is up

10 min read
An image of stacked squares with yellow flat bars through them.
Emily Cooper
Green

Perhaps the most far-reaching technological achievement over the last 50 years has been the steady march toward ever smaller transistors, fitting them more tightly together, and reducing their power consumption. And yet, ever since the two of us started our careers at Intel more than 20 years ago, we’ve been hearing the alarms that the descent into the infinitesimal was about to end. Yet year after year, brilliant new innovations continue to propel the semiconductor industry further.

Along this journey, we engineers had to change the transistor’s architecture as we continued to scale down area and power consumption while boosting performance. The “planar” transistor designs that took us through the last half of the 20th century gave way to 3D fin-shaped devices by the first half of the 2010s. Now, these too have an end date in sight, with a new gate-all-around (GAA) structure rolling into production soon. But we have to look even further ahead because our ability to scale down even this new transistor architecture, which we call RibbonFET, has its limits.

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