Strange Bedfellows

Marriage of silicon and previously incompatible semiconductors is consummated

3 min read

SILICON IS THE STUFF OF MEMORIES and microprocessors. III-V semiconductors—compounds made of elements inhabiting the third and fifth columns of the periodic table, like gallium arsenide—are the stuff of high-frequency communications chips, LEDs, and solid-state lasers. But these two types of materials have never been able to live together on the same chip. Now, researchers in Europe have found that at the nanometer scale, they can get along just fine. The researchers grew indium-phosphide and gallium-phosphide nanowires on a silicon substrate, clearing the path for the manufacture of cheaper high-frequency chips and silicon devices embedding LEDs and lasers.

A typical chip integrating these materials might consist of a silicon substrate with a large number of vertical nanowires, says Jorden van Dam of the Kavli Institute of Nanoscience at Delft University of Technology, in the Netherlands. The nano-wires could contain p-n junctions and could be embedded in an insulating polymer layer. Then, passing a current through the nanowires would cause emission of light from close to the junctions, making the device function as a tiny LED. Such nanowires could form a pixel in a display.

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A Circuit to Boost Battery Life

Digital low-dropout voltage regulators will save time, money, and power

11 min read
Image of a battery held sideways by pliers on each side.
Edmon de Haro

YOU'VE PROBABLY PLAYED hundreds, maybe thousands, of videos on your smartphone. But have you ever thought about what happens when you press “play”?

The instant you touch that little triangle, many things happen at once. In microseconds, idle compute cores on your phone's processor spring to life. As they do so, their voltages and clock frequencies shoot up to ensure that the video decompresses and displays without delay. Meanwhile, other cores, running tasks in the background, throttle down. Charge surges into the active cores' millions of transistors and slows to a trickle in the newly idled ones.

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