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Light Emitting Silicon Steps It Up 94

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)"
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Light Emitting Silicon Steps It Up

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  • by Anonymous Coward
    ... is the new acronym for Light Emitting Silicon.
  • Saab (Score:3, Informative)

    by AssFace ( 118098 ) <{stenz77} {at} {}> on Monday October 28, 2002 @08:59AM (#4546874) Homepage Journal
    Saab's newest 9-3 sport sedan has all of its electronics talking to each other over a fibre optic line - supposedly allowing more crap to be added later with greater bandwidth for cooler new features and stuff.
    I don't really see how it will have an effect on me, but I think it is a cool idea in general.

    Saab is owned by GM, soi I don't know if it is a trend that all of GM is heading towards, or if Saab is somehow special.
    • Re:Saab (Score:1, Funny)

      by Anonymous Coward
      Yeah, fiber optic also makes it easier to shield against emp attacks. Mmmmm. Hardened car. (I'm posting this anonymously so I can come back and mod myself down for OT)
    • Re:Saab (Score:2, Interesting)

      by Dread_ed ( 260158 )
      The new BMW 7 series and the new Z4 use fiber in the airbag deployment system. This has a real world effect on the safety of the automobile.

      Due to the fact that most collisions are over in a matter os miliseconds, electrically controlled airbag systems are kind of like cap-guns. In other words, as soon as they detect that one of their deployment parameters has been breached they must immediately go off. If they don't they will be too late to be effective.

      The fiber in the BMW's ISIS system allows the car to gather data from many sensors around the vehicle that help it to get a "picture" of the way the accident is developing. Not only what direction the collison is coming from, but how fast it is propigating through the crumple-zones, etc. The system then calculates the optimal deployment timing for the airbags and sets them off according to the plan it has developed. Without fiber there would not be enough time for the car to design and implement the deployment plan. Now consider, the new 7 series BMW has two front airbags, side airbags for all four outboard seats, head airbags for all four outboard seats, and knee airbags for the front occupants. Furthermore, the front airbags have multiple deployment types depending on the severity of the collision and whether the front occupants have their belts on or not. There are also pre-tensioners on the seatbelts that help make sure the driver and passenger are properly situated in the seat to recieve the front airbag deployment. ALL of this is controlled by the ISIS system.

      In addition, the 7 series has an optical entertainment bus that cotrols the stereo components, phone system, navigation system, and the DVD system. It is upgradable and expandable.

      Fiber is great for cars, no emf problems, dosen't corrode, more reliable than electrical components (no shorts), but the neatest thing that may be coming for BMW is the possible addition of Blue Tooth technology for the phone system. This would allow ANYONE in the car with a compatible phone system to use the boosted transmitter/antenna system in the car along with voice activated/handsfree operation.

      It is completely impossible to say anything intelligent or enlightening in a space this size, excep
    • and therefore the last real Saab left the assembly line sometime in '94. After that they're just another domestic abortion with domestic quality control.

      Like Jag... Volvo....ect...

      • yeah, they don't sell enough of them to make certain things feasible, so I'm just as happy that GM owns them now (I own a Saab).
        Ford owns Aston Martin, Jaguar, and Volvo. BMW briefly owned Land Rover and now Ford owns that too.
        BMW is pretty much the only luxury company left that is all by itself.
        the rest all share parts and labor to drive down costs and increase reliability.

        I personally don't like nor trust Ford, so I won't be in anything they touch, but Saab still has a great deal of freedom and control in what they do while still under GM, but now they have a larger bankroll with which to do things like the new engine that a poster above noted.
    • The only worrying thing about this is that fibre is significantly more fragile than wire. Wonder how much of a fender-bender it'll take to shatter it?


  • Google partner link (Score:3, Informative)

    by pacc ( 163090 ) on Monday October 28, 2002 @09:02AM (#4546896) Homepage
    Light-Emitting Silicon Shines Much Brighter in New Invention []
    Why can't slashdot become a partner to NYT?

    If you don't want to give google false page hits there's always majcher []
  • Integration (Score:4, Informative)

    by Drakula ( 222725 ) <tolliver@i[ ].org ['eee' in gap]> on Monday October 28, 2002 @09:03AM (#4546914) Homepage Journal
    Being able to integrate light emitting semiconductor devices together with electronic circuits is one of the holy grails of the semiconductor industry. Not only would the benefit come to increasing the speed of processors, optoelectronic devices would benefit greatly from this technology through integration. The cost savings and increased functionality would be incredible. Can't wait for it to become a reality.
    • Umm- I thought that was exactly what was said in the artical.. Did you read and quote it? Or being a slashdotter did you automatically ignore it and go to straight to the forum?
      • Re:Integration (Score:1, Offtopic)

        by Drakula ( 222725 )
        The latter. Totally Karma whored...although I wasn't the one that moderated the post up...

        My statement was also meant as more of an agreement with the article. I didn't need to read the article to know this was true because I work in the industry. I do agree that the moderation is undeserved however.

        • I disagree with your reply being modded as offtopic given that you were making a perferctly reasonable responce t justify your karma whoring... We all do it sometimes... ;-)
          I find it fairly interesting that you work in the industry- maybe you could fill in a bit more on the usual "Disneyfied" versions of the truth. Saying that- NDA and all - I know I could give industry responses to gaming topics but nothing to specific....
          • Thanks, I agree.

            I try to add value when I can. I can't contribute too much to the computer related articles beause that is not my area, I come here to learn about that. So when these semiconductor related articles pop up, I try to join in and compare my understanding to others. But alas, things get misinterpreted which is fine. It's part of the system here and I have more to worry about (like finishing my degree). Anyway, thanks for your support!

  • The Other Way? (Score:5, Interesting)

    by Anonymous Coward on Monday October 28, 2002 @09:05AM (#4546929)
    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).
    • Nitpicking... (Score:3, Informative)

      by mmol_6453 ( 231450 )
      Solar Cells == Photovoltaic Cells
      Solar Cells != Photo-Diodes

      While both are PN junctions, insofar as the construction is concerned, photovoltaic cells actually produce a voltage, while photodiodes behave...differently.

      When you have a photovoltaic cell, you need only connect a load to it to use EM energy for whatever work you need done.

      With diodes, you have one PN junction (meaning P-type material on one side, and N-type material on the other.). To forward-bias the diode, you attach your positive voltage source to the P region, and your negative voltage source to the N region. This causes your electrons (called current carriers) to be pushed across the PN junction toward your positive voltage supply.

      If you reverse-bias the diode, your current carriers will be drawn away from the PN junction, and almost no current, called leakage current, can cross.

      All PN junctions are sensitive to light in that light striking silicon will produce current carriers(disclaimer: I'm only telling half the can get confusion if you start considering "electron holes"...but if generation of free electrons bothers you, feel free.), wherever they strike. If they're particularly near the PN junction, they will serve to cause an increase in the leakage current, the external measurement of which is how the information is retrieved.

      A rudimentary photodiode is simply a PN junction with a glass window.

      There are all sorts of things you can do with semiconductors, doped or not. I keep seeing discussion proclaiming the downfall of semiconductors, but I wouldn't count on, say, quantum computing, to be able to function without supporting circuitry for the next twenty to thirty years. I hope to retire about then. :)
  • by Anonymous Coward on Monday October 28, 2002 @09:06AM (#4546941)
    120V 20A will make almost any chip glow!
  • Can someone in the know please explain what this is all about and the advantages? As usual, this article is aimed at dummies and features an indistinguishable mix of buzzwords interspersed with appropriate amounts of techie lingo, for effect. Why does a Sun designer describe it as "the holy grail" and what will it buy us? Thanks in advance...
    • by Anonymous Coward on Monday October 28, 2002 @09:24AM (#4547076)
      Here's something else (only slightly different): G20021028S001 4

      Basically, LEDs use Gallium and some other material because Silicon is horribly inefficient at photo-applications (its a electron band-gap thing, ask a physicist), but because its so cheap and GaAs is very not cheap, they still use polycrystalline Si for large solar cells.
      Unfortunately, Leds are just too dim when silicon is used, so Gallium and whatever else (depends on wavelength) is still necessary there. By getting efficient light emitting Silicon, a whole pantload of money gets saved by avoiding Gallium.

      End note: Why is Si cheaper than Ga? Refinement is more complex for Ga, Si is much more plentiful, and it hard to make large wafers of GaAs. Plus GaAs oxide (don't know the formula) is liquid at room temperature, so the only demand is photo applications (and stressed Si) because making IC with just GaAs means you can't use a liquid GaAs-oxide as a mask/gate/whatever.
      • by gus2000 ( 177737 ) on Monday October 28, 2002 @10:16AM (#4547564)
        Wow, sorry but I need to correct you on a bunch of points.

        Gallium Arsenide (not gallium) is used to make a variety of LED and semiconductor lasers. Silicon is unattractive for light-emitting applications because it has an indirect bandgap, making emission of photons much less efficient than in direct bandgap materials.

        Making large wafer of GaAs is not so much a processing issue as a cost issue (i.e. how much would one wafer end up having to sell for, and would anyone at all even think of dropping that much money on one). HOWEVER, neither GaAs nor its native oxide(s) are liquid or even water-soluble at room temperature. You were perhaps thinking of Germanium. The problem with GaAs oxides is that they do not form into such nice layers as SiO2, and that they do not effectively passivate the GaAs surface such that MOSFETs cannot be fabricated. GaAs (and InP) and still widely used (in your cellphone for example), but in different ways than silicon and not nearly as widely as silicon.
        • Augmentation (Score:2, Informative)

          by EEgopher ( 527984 )
          On the receiving end, GaAs is sensitive (A/W) to a much wider range of wavelengths than Si. Silicon is sensitive perhaps up to 1100nm whereas GaAs is sensitive in the 1500nm range. The fiber optic media exhibit minimal loss in the 1500nm range, so GaAs is the appropriate choice for receiving signals.
          I'm working on a GaAs project now, if you want to keep me company -- WRITE!
          • No, the bandgap of GaAs is larger than that of Si, meaning its absorption coefficient falls off at shorter wavelengths than that of Si (roughly 900nm for GaAs, 1100 for Si). You are thinking of InGaAs, which is the material used to detect 1.55um signals...but that is grown lattice-matched to InP, not GaAs.

            Of course direct vs. indirect bandgap also plays an important role in determining efficiency.
            • I stand corrected.
              Thanks very much.
              InGaAs it is indeed that corresponds to the 1550nm optic fibers I'm working with.

              Ever done any work with Erbium-doped waveguides, acting as optical amplifiers?
    • by bpowell423 ( 208542 ) on Monday October 28, 2002 @10:06AM (#4547458)
      The AC that replied to you pointed out the possible benefits for solar cells, but...

      The reason the Sun designer described it as "the holy grail" is timing circuitry on CPU's. What's the figure, something like 75-80% of a CPU is dedicated to timing circuitry? Think about what happens when you replace all that timing circuitry with a light pulse, and just pick it up wherever you need it. Eliminate all the wiring currently used to distribute the timing, and you get lower power, tons more silicon to devote to other things, and probably the potential for speed gains.
    • Me too! I was hoping to hear about new LED light bulbs and they start talking about, y'know, geek stuff. What a bummer.

    • by Anonymous Coward
      Several have commented on how inefficient a silicon-based integrated device is at producing light as compared to other more optimal devices long perfected in the solid state physics world.

      I find this quite entertaining for the simple reason that this same situation of efficiency mismatch was at the heart of the invention of the integrated circuit (invented independently by Jack Kilby at Texas Instruments and Robert Noyce (then at Fairchild, prior to starting Intel)). Jack Kilby in particular was struggling with the "tyranny of numbers problem." This was because,basically, prior to the coming of integration, trying to build useful circuits out of full-sized components and wire them all together was simply too complex to actually do in a practical way. Kilby needed to convince his boss to let him do an experiment where he would put more than one device together in a solid state material and he knew that TI had put a ton of effort into how to work with Silicon. He realized that even though Silicon was a "horrible" choice for making resistors and capacitors, that in fact it *could* be done and that combined with the fact that Silicon made great transistors, which are by far the most prevalent device in logic circuits, an efficient overall process might be reached. The electronics world of the time gave a collective laugh, thinking the use of non-optimal materials for the non-transistor components of this "ugly chunk of rock" was silly and that the process of making these "integrated chip things" would be way too expensive to compete with traditional circuits. We all know how things turned out. -TitaniumTurtle
  • Opto-Isolators? Duh. (Score:1, Interesting)

    by dannycim ( 442761 )
    I like this bit in the article:

    "The first applications of the new technology will be to build power control devices in which the control circuitry is electrically isolated from the power switching devices, the company said. Currently such isolation can only be achieved by using external components, adding bulk and cost to designs."

    Are they trying to re-invent opto-isolators?
    • by Cutie Pi ( 588366 ) on Monday October 28, 2002 @09:25AM (#4547087)
      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.

      • They don't have to sell their opto-isolators cheaper. They can just manufacture them cheaper, claim they're better in some way or other, and sell them at the same price. People will buy the "new better" technology and they'll turn more profit than the existing opto-isolator manufacturers.
      • They won't be making individual opto-isolators. They can use this LES to integrate isolators onto the chip. They'll have a single chip with power devices and logic devices completely electrically isolated.

    • Are they trying to re-invent opto-isolators?

      Yep. They did. See their web site. (Sorry, don't have time to copy the link from another posting...)

      But when THEY make an opto-isolator they put the emitter(s) and the detector(s) on the same chip, getting the alignment between them by using the same set of masks. Then they convert the region between the two sides into silicon Dioxide (also known as "glass") to form a VERY GOOD transparent insulator without disturbing the alignment.
  • Sounds like yet another PR job - the article speaks of nothing that is really new. Just shows whether you're an academic struggling for funding or a technocrat, the battle's about the benjamins.. How many of these have we seen? C'mon let's get real.
  • by Zack ( 44 ) <`moc.liamg' `ta' `hairodez'> on Monday October 28, 2002 @09:11AM (#4546981) Journal
    Great! Now strippers can do their own light shows! (Okay, it's silicon vs silicone, but shhhhh, it's funnier that way)
  • by Cutie Pi ( 588366 ) on Monday October 28, 2002 @09:12AM (#4546988)
    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.
    • by Drakula ( 222725 ) <tolliver@i[ ].org ['eee' in gap]> on Monday October 28, 2002 @09:32AM (#4547139) Homepage Journal
      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.

      • I have made these kind of devices for my master's thesis and the way how native silicon emits light is called nanocrystalline theory. Si is confined into a host material as sio2. When these silicon nanoclusters are small enough they act more as direct band gap materials due uncertainty pricniple. The real process is of course more complex but don't be too quick to say that si can't emit light as efficiently as GaAs based structures. Btw GaAs is optically poorer light emitter because of its hihger refractive index than sio2. This affect for example to critical angle.

        • I was speaking of single crystal Si.

          The extraction efficiency of GaAs is limited by the critical angle, you are correct in this. However, this can be overcome to some degree by microcavity structures ot photonic bandgap structures. Still the material must have a high internal quantum efficiency to produce a large amount of light, single crystal Si alone does not have this. Doped Si may be better but it is still going to be much lower than the near 100% acheivable in GaAs.

          • True signle crystal Si is very poor light emitter, this is because it needs phonons to emit (or is indirect band gap material), but it is a different thing than silicon nanocrystal structures where si is confined in silicon dioxide matrix. There is many ways to alter bulk silicon properties. Silicon nanocrystals are produced into a silicon dioxide layer by ion implantation. After implantation the wafer is heated in inert nitrogen atmosphere where silicon clusters form. This is still new technology. Light emission from amorphous silicon was invented 1991. Light emitting silicon dioxide layers havent been even in laboratories for more than five to six years. Of course the optimal process is not invented yet. There wouldn't be much to research in that case. I believe that in future silicon based led devices will be as efficient as GaAs devices are today. Simply because there is a demand for Si based optoelectronics.

      • Oh and few more things. In Si doped sio2 devices the emitted wavelengt can be directly altered by altering the size of the si nanocrystal if we assume that the light is emitted due to straight recombination in nanocrystal. Also different rare earth elements emit light in different wavelengths. If the light spectrum is too wide, it could be modified for example with photonic band gap structures, a subject I'm also studying. These kind of structures could provide even a single mode aka laser operation in conventional LED devices. phew. never say never.

        • This is what I was refering to. Photonic crystals are resonant structures that can enhance the emission or propagation of certain wavelengths in a structure.

          Even with this help, single crystal Si will never be able to produce ligth as efficiently as GaAs.

    • by Anonymous Coward
      light-emitting semiconductors such as GaAs

      When I have GaAs, my emissions would not be considered "light".
  • by zozzi ( 576178 ) on Monday October 28, 2002 @09:14AM (#4547003)
    "No Sir I wasn't staring at her breasts, I was just attracted by the light coming out of her shirt"

    "Case dismissed!"

  • These processors are going to be useless to photographers that develop their own film using computers. The film has to be processed in a dark environment, and a light-emitting processor could damage or even totally ruin delicate undeveloped photographs. However, with film photography going the way of the dinosaur due to the advances in digital photography, it probably won't matter too much.
    • you have obviously never developed film before. it requires chemicals (developer, stop, water, etc.), graduated cylindars, a reel to put the film on, a tank to put the film in, a dark room to do it in and a clock to time it.

      this is how film is processed, no computers at all, unless you consider teh clock a computer.

      please clear your ignorance cache before posting again.

    • I would give the benefit of the doubt to the author and assume that they realize the "film" developed on a computer is digital media and not photosensitive.

      Instead, a more reasonable assumption is that it is intended as humor. Now while various people might disagree as to how funny it might actually be, I think your troll moderation is, well, immoderate. Evidently, I am not alone, Quill_28, also raises the question, "How is this a troll". Subsequently someone has demonstrated for him, by marking the inquiry itself troll.

      I have been getting moderater points fairly frequently. I try to use them with more care than this.

  • Glow? (Score:5, Funny)

    by e8johan ( 605347 ) on Monday October 28, 2002 @09:17AM (#4547032) Homepage Journal
    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!" :)
    • By then, most processors will use a few kW of electricity, so this would be great for discotheques. No more disco lights would be required.
    • Re:Glow? (Score:5, Interesting)

      by Cutie Pi ( 588366 ) on Monday October 28, 2002 @09:34AM (#4547158)
      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?)
      • The light that GaAs emits is in the infrared. So unless you have some heat detection goggles there wouldn't be much to see.

  • by athlon02 ( 201713 ) on Monday October 28, 2002 @09:39AM (#4547221)
    No more need to buy cases with neon lights in them... just grab the latest motherboard from your favorite mobo manufacturer and voila :)

    But in all seriousness, after I saw the article a while back (on slashdot) with something about optical traces on a motherboard in about 5 years from now, it had me very intrigued. I mean if you can shave a few nanoseconds from every bus cycle that's gotta be worth 10% increase in performance eventually. Especially on a clawhammer/sledgehammer where you've eliminated the north bridge part of the chipset.
  • by e.m.rainey ( 91553 ) <> on Monday October 28, 2002 @09:41AM (#4547243) Homepage
    For those of you who don't like to register...

    Google News (Beta) Link []
  • new math (Score:4, Funny)

    by the_pooh_experience ( 596177 ) on Monday October 28, 2002 @09:41AM (#4547246)
    "...researchers have succeeded in increasing the efficiency of light- emitting silicon 100-fold..."

    well now, let us see.. 100 times ZERO. Maybe that "new math" [] we all learned can help us with this.

    Please forgive this post, I am a bitter III/V (read GaAs et al) guy

  • LES Hardware (Score:2, Insightful)

    by MadocGwyn ( 620886 )
    People keep saying it'd be cool to see the 'flashing' of LES CPU's etc, or the blue green codeing guys comment. You do relize, they would be flipping so fast that you would not be able to see the change, just a glow.
  • by Anonymous Coward
    Ok, should read the story first...
  • Skip the NYTimes reg crap and read it here: STMicro claims light-emitting silicon breakthrough []
  • I've had light emitting silicon for years, though I admit it is not quite as flexible as this newer technology.
    Most of you probably do and don't even know it. Simply remove your Athlon heatsink, and for a brief period, the chip will emit a reddish glow.
    It is pretty, but DO NOT touch.
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