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Light Emitting Silicon Steps It Up

Posted by Hemos on from the move-that-data-faster dept.

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)"

10 of 94 comments (clear)

  1. Re:The coolest part of this story... by Daath · · Score: 5, Funny

    LIght Emitting Silicon? - LIES
    ;)

    --
    Any technology distinguishable from magic, is insufficiently advanced.
  2. The Other Way? by Anonymous Coward · · Score: 5, Interesting

    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).

  3. Light emitting silicion is easy. by Anonymous Coward · · Score: 5, Funny

    120V 20A will make almost any chip glow!

  4. Light Emitting Silicon?! by Zack · · Score: 5, Funny

    Great! Now strippers can do their own light shows! (Okay, it's silicon vs silicone, but shhhhh, it's funnier that way)

  5. Very challenging to do by Cutie+Pi · · Score: 5, Informative

    One of the things this article really doesn't elaborate on is just how difficult the road has been to make efficient light emitting silicon. I had a professor as an undergraduate at the University of Rochester who spent a significant amount of time trying to get it to work. The article doesn't go into the technology, but I'm guessing they're using porous silicon. Porous-Si has small nanometer scale pores in (etched via electochemistry). The pores effectively alter the band gap of the silicon, increasing it to that of the compound light-emitting semiconductors such as GaAs. While this technique works well at generating light, the problem is getting it to generate light efficiently. Hence the exotic rare-earth materials such as erbium. I'm impressed that STMicroelectronics was able to increase the light output 100-fold. Extravagent claims such as these make me want to take a wait-and-see attitude. The process might be so difficult that it wont be practicle on high-performance chips for some time. Also, the processing techniques of light emitting silicon is different than for standard logic. I'd like to see how well these two processes can be merged.

    1. Re:Very challenging to do by Drakula · · Score: 5, Insightful

      You have a very good point.

      However, the fact that Si has an indirect bandgap means it will never be as efficient as its direct gap brethren, such as GaAs.

      The addition of a rare earth element such as Erbium increase the light output substantially as you say. However, the emission spectrum is very broad and likely undesired. A rare earth dopant and a resonant cavity structure however would be a good candidate for efficient emission.

      --
      "It's comin' back around again..." -RATM
  6. I can see it already... by zozzi · · Score: 5, Funny
    "No Sir I wasn't staring at her breasts, I was just attracted by the light coming out of her shirt"

    "Case dismissed!"

    --
    ---
  7. Glow? by e8johan · · Score: 5, Funny

    Does this mean that part of the heat from the CPU will be light in the future? No more "monitor glow", more like "computer glow"... perhaps if different parts had different colours, e.g. floating point = green, integer = blue, cachemiss = red. Then you would know what part of your code to optimize without running a profiler: "It's all green and f**king slow, make your inner loops fixed point, dumbass!" :)

    1. Re:Glow? by Cutie+Pi · · Score: 5, Interesting

      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?)

  8. Re:Opto-Isolators? Duh. by Cutie+Pi · · Score: 5, Interesting

    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.