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Light Emitting Silicon Steps It Up
h4mm3r writes "STMicroelectronics plans to announce a breakthrough on Monday in light-emitting silicon that could lead to a new generation of more powerful computing processors and more efficient automobile components as well as
potentially higher-speed optical data-transmission systems. (gotta register, free yadda yadda)"
I'm more curious about whether this could make photo-sensor diodes (read: solar cells) more efficient as well. That could lead to widely used poly-silicon being a reasonable alternative to Gallium Arsenide as far as power (whereas now, it's used solely due to cost).
This sounds like what they're going to be doing at first... The article points out that current opto-isolators need to be made with external components, whereas these would be made as a monolithic device. Still, opto-isolators are fairly cheap. I wonder how STMicroelectronics plans on selling these for cheaper. Eventually, I think the long term goals for this technology (if it proves to be really useful) is for use in high-performance logic chips. The problem with clocking large scale chips (such as CPUs) is that the clock signal has to arrive at all the gates at the exact same time. This is actually a very big challenge because resistance*capacitance slows things down. Trying to propagate a signal all the way across a chip to a large number of gates means that you need large driver transistors to supply the large current necessary. With optical clocking, you eliminate the RC time delay. You simply need to generate a pulsed optical signal and then make conduits across the chip to channel it to all the gates.
Of course, I'm guessing that is not as easy as it seems, which is why STMicroelectronics is making simple devices like opto-isolators. It could be several years before optical clocking is perfected.
Actually GaAs chips do emit light while they are running. (I always though it would be cool to have a glass case over the chip, like they do with EPROMs, so you could see it working).
Standard silicon does emit radiation, but it's all in the infrared. IBM actually invented a technique a few years ago that essentially looks at a chip under a microscope with a high-speed IR camera. You can actually see gates turning on because they appear as bright spots in the camera. This technology is useful for diagnosing problems with silicon. (For example, if you're getting too high a current draw, you can see transistors that are on when they're supposed to be off. Did that designer forget to draw a wire to ground?)