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Light-Producing Nanotubes Could Mean Faster Chips 181

Posted by timothy
from the making-light-of-carbon dept.
CannibalBob writes "From PCWorld: Researchers at IBM have used carbon molecules to emit light, a breakthrough that could replace silicon as the foundation of chips and lead to faster computers and telecommunication equipment. This is the first time light has ever been generated from a molecule by applying electricity. Read the article."
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Light-Producing Nanotubes Could Mean Faster Chips

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  • by c_oflynn (649487) on Monday May 05, 2003 @04:35PM (#5885133)
    This is the first time light has ever been generated from a molecule by applying electricity

    I always assumed with enough power ANYTHING could emit light.. if only for a brief time
    • I always thought this was how an LED worked....
    • Not only that, I didn't see it mentioned in the article. What is our honoured submitter smokin'?

    • Re:First Time... (Score:5, Insightful)

      by aSiTiC (519647) on Monday May 05, 2003 @04:45PM (#5885237) Homepage
      I believe that the point is that a single molecule is emitting light. A light bulb utilizes billions of molecules of tungsten to emit light.

      The whole point being that a carbon molecule/nanotube could be the equivalent of a light transistor in the optics world.
      • Re:First Time... (Score:5, Informative)

        by L7_ (645377) on Monday May 05, 2003 @04:50PM (#5885278)
        a single molecule emits light whenever it makes a state transition... Its the phenomenon that caused the paradigm shift from classical to quantum mechanics.

        That can't be the point.
        • Re:First Time... (Score:5, Informative)

          by civilizedINTENSITY (45686) on Monday May 05, 2003 @05:07PM (#5885423)
          Yes, it is the point. Although it happens molecule by molecule when it happens in mass, there wasn't a way to control the applicatiion of a signal and stimulate emmision from a chosen molecule. Now there is. For the first time ever, *a* molecule is made to emit when electrically stimulated.
          • Single-crystal semiconductors don't count?
          • Hrmmm.... lets look at the name.
            OK, sorry, cheap shot. I work with this stuff... and carbon has been emitting light for a very long time. If the focus is a specific molecule, well, look at dopants- thats where the energy is released (hence the name)... and thats where the light comes from. Hosts provide the path.Kodak OLED information [kodak.com]
          • Re:First Time... (Score:3, Interesting)

            by L7_ (645377)
            No, its not.

            IIRC, one of the more recent topics in modern biochemistry/biophysics is isolating DNA 'molecules' (about the same size as some of the carbon tubes) and exciting them in different ways. Different ways that include photon and electron scattering (or 'passing electricity').

            I'm not too sure on the results, and was too lazy to find the correct terms through google, but i know that single molecule systems have been seen to produce light through electron scattering.
          • Re:First Time... (Score:3, Interesting)

            by Goldsmith (561202)
            What they're really claiming is the world's smallest solid state light emmitter. I guess if you define a nanotube as the smallest possible solid state structure, there you go.

            Dr. Wilson Ho [uci.edu] has been doing this for a while at UCI with individual atoms.

            You really should check that out. It's hard to believe, but true.
        • Re:First Time... (Score:1, Redundant)

          by homer_ca (144738)
          That's also how neon lights work at the atomic level. Electricity excites an electron to a higher orbit, electron gives off light when it drops down to its original orbit.
    • Re:First Time... (Score:2, Redundant)

      by magnum3065 (410727)
      Well, Black Body Radiation is the phenomenon where something emits light as it is heated up, and yes this means that you can make pretty much anything give off light by making it really hot. This is how incandescent light bulbs work, the tungsten filament has a high resistance, so when electricity passes through it heats up and gives off light. Though this article is slim on the details, I imagine this new discovery does not involve simply causing the molecules to heat up to the point where they emit ligh
    • by tellezj (612044) on Monday May 05, 2003 @04:53PM (#5885312)
      would constitute a single molecule. Applying electricity to it, as pointed out in the article, they were able to produce light (1.5 micron). An LED, tungsten wire, or burning lump of coal are not made up of a single molecule, no more so than an ice cube is a single molecule of water. What this constitutes is an engineering first. What is left to be seen is if they can find useful applications and mass produce it.
    • Re:First Time... (Score:4, Informative)

      by Hayzeus (596826) on Monday May 05, 2003 @04:58PM (#5885346) Homepage
      That would be from a SINGLE molecule; nanotubes are single molecules. More handy dandy info at IBMs nanonotube web site [ibm.com].
    • Re:First Time... (Score:1, Interesting)

      by Anonymous Coward
      ... with enough power ANYTHING could emit light.. if only for a brief time

      A classmate of mine managed to get an ordinary transistor to generate light. The case drew blood, where it hit his forehead. Yes, it was a very brief flash.

      Someone else already pointed out that getting light out of a single molecule really is new. Unless you count burning Buckyballs.

  • First time? (Score:4, Interesting)

    by Anonymous Coward on Monday May 05, 2003 @04:36PM (#5885144)
    How do light bulbs work? True, they burn as a side effect of being heated, but you apply electricity, and you [eventually] get light. Then there's the the whole laser thing... Florcent tubes?
    • Re:First time? (Score:2, Insightful)

      by Anonymous Coward
      I believe they mean that the electricity directly creates light. In a regular light bulb, the electricity heats the element (tungsten in most cases), which then produces light from the heat. In chips, heat is a Bad Thing(tm), and getting it directly from electricity, and producing very little heat, would be a Good Thing(tm).
    • Re:First time? (Score:5, Informative)

      by f97tosc (578893) on Monday May 05, 2003 @04:52PM (#5885301)
      How do light bulbs work? True, they burn as a side effect of being heated, but you apply electricity, and you [eventually] get light. Then there's the the whole laser thing... Florcent tubes?

      Well, any light form needs energy - and electricity is a common way of providing this.

      Light bulbs emit light because they are heated by electricity. Unfourtunately, about 95% of the light emitted is not visible to humans, and thus wasted (human eyes are tuned to best view light from a certain body at about 6000 degrees, and this is much hotter than the light bulb - thus the inefficiency).

      There are, however, ways to convert electricity to light without heating anything. LEDs do this - all energy is converted to light of a single certain frequency - which we can see. This is true for lasers also, but they go even further by not only having light of a single frequency but also aligning the light waves that compose the light.

      But both light bulbs and LEDs are made of big crystals of metal / silicon (as opposed to molecules). What is new here is the atomic structure of the of the light emitting material; it is nanotubes which technically are big molecules. This is a major discovery - although it is probably too early to tell exactly what it will be useful for in the future.

      Tor
    • No, they're not talking about heating up tungsten. A good analogy for how light is generated in that manner is that the resistance of the tungsten is similar to friction, and as the electrons pass through it, they heat it up, eventually resulting in light. This phenomenon involves interactions between positive and negative charges in a nanotube resulting the release of light - a bit different from the analogy of releasing mechanical energy needed to force the electrons through medal as heat. I never much
    • by jkauzlar (596349) on Monday May 05, 2003 @05:00PM (#5885364) Homepage
      Its very complicated for a layman to understand, but I'll do my best:

      The molecules in a light-bulb filament (called lightrodes) are ramp-shaped. When the electricity flows along the filament, some of the electrons hit this lightrodes and they fly out into the room. Hence, the light you see is simply dispersed electricity. It sounds crazy, I know, but, that's where static electricity comes from! How else would you explain electricity getting onto the carpet?

      I would explain florescent lights, but you would need an advanced degree in science (30+ yrs of school) to even understand the basic concepts.

    • I always hoped the intelligence of people who approve stories was higher than that of the average reader. Apparently this isn't the case.

      Put the brains back behind slashdot. Perhaps if we apply enough electricity their brains may shed some light....
  • by KCardoza (593977) on Monday May 05, 2003 @04:39PM (#5885172) Homepage
    Wouldn't ignorant jackholes who read too many bad sci-fi novels like Bill Joy worry about these "Nanotubes" going haywire and turning the planet to gray goo? Or would Apple sue them into oblivion for using "Carbon" in a computer without their express permission?
    • by Steffan (126616)
      I don't think Bill Joy's issue is with Nanotubes per se, but with self-replicating nanomachines that could, due to a 'programming' bug or something similar, not stop replicating even after their task is done, hence the 'gray-goo' you hear about. It's a legitimate concern, but IMO should not and does not justify the cessation for nanotechnology research.

  • by bearl (589272) on Monday May 05, 2003 @04:39PM (#5885177)
    >This is the first time light has ever been generated from a molecule by applying electricity.

    Heck, if you put too much lighter fuel on the charcoal and apply your electric grill lighter while standing too close you'll see PLENTY of light from those charcoal molecules!

    • Ah, but the challenge here is to spray your lighter fluid onto a single charcoal molecule, and then ignite it.

      Then the double challenge is to make a good barbeque out the result.
    • Am I the only one that remembers those guys from Purdue who would light their charcoal grills with LOX? Combustion gave off so much light you could barely see anything in the pictures...

      Oh man...

      They didn't have a barbeque so much as a hunk of melted metal with some carbon molecules left over.

      ...but "they" (whoever they are) pulled the site...*teardrop*
      Anybody know of a mirror?

      • Well, that frigging figures. Chalk up another victory for the terrorists. It was probably pulled because of the side caution to pour the LOX on after placing the lit match on top of the stack (if you were so inclined as to risk your life in such an obviously hazardous manner by imitating them). They went on to explain that if you let the LOX soak in first and then applied the match, each briquette would be equivalent to a stick of TNT...

        *sigh* Got halfway into a nice rant about the right to think before ba
  • by JUSTONEMORELATTE (584508) on Monday May 05, 2003 @04:39PM (#5885181) Homepage
    ...and lead to faster computers and telecommunication equipment.

    Doesn't it seem like this catch-phrase is tacked onto every new discovery? Couldn't these folks just be making nifty flashlight bulb replacements? Does EVERYTHING need to give us faster computers?

    --
  • by AlabamaMike (657318) on Monday May 05, 2003 @04:43PM (#5885218) Journal
    Self assembly, high tensile strength, readily available (at least for Carbon), and now light emitting! What is is that carbon nanotubes can't do? It seems everyday there's a new application for these things. I'm ready for the guys @ Highlift to buckle down and just get the space elevator done. Maybe while their at it, they could use the nanotube cable as some type of large transmission line for the Interplanetary Internet!

    -A.M.

  • Mass Production (Score:3, Insightful)

    by L7_ (645377) on Monday May 05, 2003 @04:46PM (#5885253)

    Pardon me for being skeptical (I am a theorist, not an experimentalist), but isn't there a revolutionary new 'Carbon Nano-tube Technology' every 2 months? I mean, how many of these technologies will be applicable with thier current specifications?

    And not only that, but it seems that nano-tubes are not currently being mass produced in any reasonable way. If they are, why aren't more small graduate materials labratories basing research on them?

    I'm not against plausible speculations to applied science, but it just seems that the carbon nano-tube technology is still in its beginning phases, and we won't see these 'small optical fibers' or any other applied devices anytime before 2020.
    • Re:Mass Production (Score:1, Informative)

      by Anonymous Coward
      That's the major problem they've had...the things are pretty damn hard to manufacture with any quality.

      Thankfully, some newish production methods are being put through, and a couple dedicated factories are being built. From what I read in new scientist, it should drop the price down to $5/kilogram instead of $500/milligram (or some similar outlandish figure)
    • I'm not against plausible speculations to applied science, but it just seems that the carbon nano-tube technology is still in its beginning phases, and we won't see these 'small optical fibers' or any other applied devices anytime before 2020.

      The first semiconductor transistor (the point-contact transistor) was produced in 1947. The junction field-effect transistor was invented a few weeks later, and the first working prototype was produced in 1949. By 1958 integrated circuits were being made with them.

    • by wass (72082) on Monday May 05, 2003 @05:30PM (#5885575)
      yes, nanotech is currently one of the 'sexy' topics, and so every two months (or more often, usually) someone gets to publish their new fabrication or measurement technique.

      I'm a graduate physics student (experimentalist), and I'll be working with nanotubes. But we're just building up our lab now (my advisor just arrived here only a few months ago). We'll be doing measurements with carbon nanotubes, initially continuing what we did last summer (at her old postdoc lab) by measuring superconducting nanowires. If you're curious, these nanowires are created by sputtering a superconducting alloy (MoGe) on top of a nanotube substrate. They're interesting because the system dimensions are small enough that the wires are effectively one-dimensional, which means they can't support long-range order and thus cannot allow Cooper-pair supercurrents to flow unimpeded through the wire.

      It's hard to create nanotubes, and harder to put them where you want them. One way to create them is to use chemical vapor deposition (CVD), where you basically try to create a controlled environment where some hydrocarbon (eg methane) is ignited (the environment is somewhat oxygen-deficient so CO2 isn't the only carbon species produced) The 'soot' that is subsequently deposited on your substrate should contain nanotubes if the right conditions are met.

      To get the tubes in certain places, sometimes little 'seeds' of iron particles are used, in hopes the nanotubes will grow/branch from them. It's hard to create good SWNT (Single-Walled Nanotubes), but easier to form 'ropes' of many nanotubes intertwined together.

      Another difficult factor to control is the 'chirality' of the tube. Basically, a carbon nanotube is a rolled graphite sheet, but when the sheet is rolled, it can have certain 'twist' to it. For example, if you rolled lined paper into a cylinder, you can have zero helicity, in which case your lines will form independent circles. Or you can shift the lines by an integer number, in which case the lines will form helices of varying pitch. This factor in nanotubes determines the electronic band structure, which mandates whether the tubes are metallic or semiconducting. It would be highly desirable to be able to produce consistently tubes of the same chirality.

      I hope this makes sense, I was up all night doing E&M homework (ya gotta love Jackson), so my brain is kinda fried right now.

      • It makes sense. :)

        And the reason that I bring up mass production of the stuff is because it is often overlooked. I mean, Kroto and Smaley (the scientists that discovered fullerenes and won the nobel prize for it) analyzed spectrums to determine that there was a new form of carbon, but they couldnt separate it from the 'soot' and noone could really do experiments on it.

        I know this because one of my undergrad profs at UofA Dr. Huffman talked about it quite a bit when he was able to use an enzyme to separate
      • Yeah, I can tell your brain is fried. But you still managed to give a clearer picture of the current state of nanotech than any of the gee-whiz stuff I've read recently. Lots of nanotech enthusiasts seem to think it's like building radio-controlled cars, only smaller. Please consider starting a blog or something!
  • Stability (Score:3, Interesting)

    by tijnbraun (226978) on Monday May 05, 2003 @04:47PM (#5885259)
    I'm a complete ignorant about these things. But how stable are these systems that work on nano levels? For instance if I would give my computer a hard kick, would it be affected in any way? The energy levels it works on are so low.
    • For instance if I would give my computer a hard kick, would it be affected in any way?

      You mean our non nano-level computers shouldn't be affected if I give it a hard kick? Dang!!! Shouldn't have trusted that guy when I tried to RMA my Dell...

  • Nano Nano (Score:2, Funny)

    by ackthpt (218170) *
    Light-Producing Nanotubes Could Mean Faster Chips

    Yeah, then kill you because nanostuff gets through your skin and the light give you malinoma from the inside.

  • Nanotube display? (Score:4, Interesting)

    by Tyrdium (670229) on Monday May 05, 2003 @04:52PM (#5885304) Homepage
    If they managed to refine this enough, could we be seeing nanotube displays some time in the future? And how would the power drain compare to that of an LCD or OLED display?
    • Re:Nanotube display? (Score:4, Interesting)

      by AttillaTheNun (618721) on Monday May 05, 2003 @05:53PM (#5885748)
      Exactly what I was thinking. Imagine the resolution you would get from a 21" nano-tube display. At 1.4 nm diameter, assuming you could align these in a perfect grid (and my math isn't totally screwed up), you would have a theoretical max resolution of 17.857 million dots/inch or 375,000,000 x 281,250,000 pixels in a 21" screen :) You'll need a mofo graphics card to drive it, of course :)
      • At 1.4 nm diameter ... you would have a theoretical max resolution of 17.857 million dots/inch or 375,000,000 x 281,250,000 pixels in a 21" screen ...

        And we'd find out how many applications all crash because they're using 16-bit integers to track the display resolution. Of course, some of us may have a bigger problem buying the 281,025 gigabytes of video RAM may be a bigger problem for you.

        You want how much memory capacity on the GeForce-5 chipset now???

  • Okay, we got electricity->light. but now we need something else to get it back to electricity iff light present.
    • Obviously, you use the light, run back through nanotubes, to turn into electricity. See also: LED's and Solar Panels (which are also essentially diodes) Every $%@ physical process is reversible.
  • After looking at the Babel-dy-gook of translations of the PPC 970 article, everything I read on slashdot had the appearance of broken English. Sigh. This too shall pass.

    Anyways, couldn't they get much better performance if they had a electrical signal that had a not so fast not so regular repeating pattern of pulses of light and then used a second out of phase signal to modify it to get the correct pattern. Both signals could run at a lower rate (leaving room for improvement and lowering costs of developm
  • Thursday's announcement won't translate into products for quite some time, Avouris said.

    Yes. The article doesn't mention much about how light will be recieved (though I suspect it will just happen in the reverse - light will generate electricity), and it also fails to point out that with the immense complexity of today's chips, it wouldn't be just an easy jump to convert existing designs to accept light pathways over silicon. This would require a new industry apart from the semiconductor sector, with ne

  • by Poeir (637508)
    Since this is carbon, would it be possible to begin development on an organic computer that grows? Or is that still a ways off? I mean, I know they have windshield that "heal," and I think that works on a similar idea, but how far away are machines that are grown, rather than built?
  • by OrbNobz (2505) on Monday May 05, 2003 @05:04PM (#5885397) Homepage
    Would it stand to reason that these devices would _generate_ electricity when bombarded by photons? Or would they be destroyed?
    I'm sure several orders of magnitude more of these nanotubes would fit in the space of a solar cell.
    Stephenson's aerostats just might work. :)
    Perhaps someone with a background could answer.

    - OrbNobz
    I don't care about the answer, the nano-machine operating my fingers is asking.
    • Would it stand to reason that these devices would _generate_ electricity when bombarded by photons?

      Nope, they explode [slashdot.org]
    • Would it stand to reason that these devices would _generate_ electricity when bombarded by photons? Or would they be destroyed?
      I'm sure several orders of magnitude more of these nanotubes would fit in the space of a solar cell.
      Stephenson's aerostats just might work. :)
      Perhaps someone with a background could answer.


      Well, I don't know about that, but you might be able to pull somebody who doesn't know jack about electricity, solar cells, or nanotubes, but is extremely opinionated, and they could say s
    • In principle, yes. That's how solar cells and photodiodes work. Now, just because something is efficient at converting electricity into light, however, doesn't mean that it will be similarly efficient at converting light to electricity. Generally, devices are usually specialized toward one function or the other. I suspect that nanotubes wouldn't be that great as photocells. For one, you can already make high efficiency semiconductor photocells with large surface areas (important for light collection!),
  • Now, not only can we build nanotube fiber cables to orbit, but we can light them up at night too!
  • by Anonymous Coward
    they're talking about making a MOSFET? I can't imagine them creating a light BJT...how would that work, anyway? Is beta then the ratio of the number of photons?
  • Hmmm.. I notice NanoGator is suspiciously missing from this discussion.

    Oh my god! They've killed NanoGator with their evil research! Those bastards!

    It's a joke - laugh.

  • by valmont (3573)
    imagine a blinding, sunshades-requiring, skin-melting, vampire-killing, burn-baby-burn, let-there-be-FUCKLOADS-of-light beowulf cluster of those.
  • Light (Score:1, Insightful)

    by 56ksucks (516942)
    I once saw some cheesy scientist on the tonight show or letterman or whatever get light from a pickle! He stuck two forks in each end and connected each fork to the AC and the pickle lit up! I'm not sure what this has to do with computers but it was pretty cool!
  • Posted on physicsweb (Score:5, Informative)

    by parkanoid (573952) on Monday May 05, 2003 @05:27PM (#5885560)
    Three days ago [physicsweb.org]
  • by back@slash (176564) on Monday May 05, 2003 @05:28PM (#5885564)
    Optical computers have been discovered? Superconducting fibre will soon follow and we will be able to build the dreaded gatling laser!
    After that it is only a matter of time before fusion power is harnessed and our units are twice as strong as the enemies!

    /discoveries according to Alpha Centauri
  • Couldn't we just apply electricity and make all the carbon's in our bodies glow?
    • Re:Make humans glow! (Score:3, Informative)

      by wass (72082)
      Couldn't we just apply electricity and make all the carbon's in our bodies glow?

      I don't know how facetious you're being, but I'll answer anyway. The carbon atoms in a carbon nanotube are in a highly ordered arrangement (a nanotube is essential a crystal with well-defined point symmetry groups), which means the potential energy (ignoring end-effects of the tube) is invariant under certain symmetry operations, namely translation and rotation. These symmetries will manifest themselves when you solve Schro

  • After they perfect whatever process they used to develop this; theoretically, chips should be cheaper since fairly pure sources of carbon are fairly abundant (graphite, coal, ...). Of course this is assuming that manufacturing cost of it isn't some astronomical figure.
  • In high-school physics/electronics class, I used to get the lead out of a Pacer (propelling pencil, not a car), put it between two alligator clips and run 12 volts DC through them. Just like a light bulb, it burns rather brightly. Just unlike a light bulb, I didn't have it encased in a glass-sealed vacuum. Not to be funny, but I got a LOT of molecules to emit light just by applying electricity to them.

    Having RTF(under-detail-laden)A, a couple of questions spring to mind:

    1) What's done to prevent the rapid
    • What's done to prevent the rapid over-oxidation, especially in something that astonishingly thin?

      In your experiment, the graphite glowed because it got hot. It also oxidized because it got hot. It's a simple case of resistive power dissipation.

      In this case, the carbon is emitting light through a quantum process, not thermal radiation. The graphite doesn't get hot and therefore doesn't oxidize.

    • Yeah, but lets see you light up ONLY 1 molecule.
  • At last, something strong enough to make a light saber out of!

  • - L.A.S.E.R. light
    - Light Emitting Diodes
    - electriluminecent films
    - Organic polymeric light (OLED)

    All of these and -more- emit light when an electrical voltage is applied. One molecule at a time, even though there are plenty of them in aggregation.

    So, the nanotube emitters are wonderful... but hardly the first. Just the _latest_. Still extremely interesting technology nonetheless.

  • by BigBadBri (595126) on Monday May 05, 2003 @07:12PM (#5886412)
    that these nanotubes happen to emit at around 1500nm, which is a good wavelength for fibre optics?

    Thinking about it, would it not be feasible to make them emit harmonics (375nm blue, anyone?) for use in optical storage too?

    I'm just a dumb old maths guy, not a physicist, but surely someone can enlighten us?

  • by VCAGuy (660954) on Monday May 05, 2003 @07:56PM (#5886716)
    In theatrical lighting, the power stage is separated from the signal side by an optocoupler--which basically ensures that if the power stage leaks 240VAC, it won't travel down the DMX wire and fry everything else.

    I wonder if they could use these "lighted" carbon nanotubes to put an optocoupler directly on the IGBT of the dimmer...that, as my coworkers would say, would be "freakin' awesome"!
  • nanoprinting? (Score:2, Interesting)

    by Dossy (130026)
    I'd like to know if these light-emitting nanotubes can be used for nanoprinting of ultra-dense transistor chips. Talk about entering into the next age of computing power ...

    -- Dossy
  • by Pooua (265915) on Monday May 05, 2003 @09:15PM (#5887191) Homepage
    Silicon, the main material used in semiconductors, does not emit light, and therefore can't be used in optoelectronic products, Avouris said.

    I beg to differ. Silicon has been made to emit light in various ways for over a decade.

    "Scientists at Surrey University, led by researcher Kevin Homewood, are showing off a prototype silicon-based light-emitting diode (LED) -- an invention that could be of significance to the whole electronics and communication industry.

    "By enabling silicon to emit light, the scientists say they may have found a way to use light to efficiently transfer data around microchips. This could lead to smaller, more powerful computers and improve data communications significantly."

    ZDNet UK: Light-emitting silicon boosts chip speeds: 8th March 2001 [zdnet.co.uk]

    "The photoluminescence emanating from a regular array of 1.2 m sized dots composed of Si nanocrystals was studied with spatial, spectral and temporal resolution."

    New Journal of Physics: Nanostructuration with visible-light-emitting silicon nanocrystals [iop.org]

    "GENEVA, Switzerland -- STMicrolectronics claims to have achieved a breakthrough in the creation of light-emitting silicon and said it would have engineering samples of monolithic silicon devices based on the technology, combining electrical isolation and optical communication, before the end of 2002.

    "The development allows silicon light emitters to match the efficiency of compound semiconductor materials such as gallium arsenide for the first time, the company said."

    EE Times: STMicro claims light-emitting silicon breakthrough: October 28, 2002 [eetimes.com]

    "The discovery of visible luminescence from porous silicon [1] has stimulated a large interest in this material. Numerous studies have demonstrated that it is possible to achieve efficient visible luminescence from porous silicon layers [2]. This material system has significant economic potential as efficient visible emitters could be fabricated on silicon wafers and incorporated with current microelectronic devices using existing silicon processing technologies."

    [1] L. T. Canham. "Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers." Appl. Phys.Lett., 1990, 57 1046 - 1048.

    [2] For a recent review of the work in porous silicon see : Thin Solid Films, 1995, 225 and "Porous Silicon", edited by Z. Chuan and R Tsu, World Scientific, Singapore, 1995.

    A Visible Large Area Light Emitting Diode Fabricated From Porous Silicon Using A Conducting Polyaniline Contact [dur.ac.uk]

    BTW, technically, photocells are optoelectronic devices, as are LEDs.

  • by jmichaelg (148257) on Monday May 05, 2003 @09:37PM (#5887280) Journal
    Doesn't anyone remember this? [rpi.edu] Nanotubes seem to catch fire when you take pictures of them with a flash camera. How is putting light inside the tube going to take care of this *small* problem?
  • why my computer lights up when it is running, doesn't it?

I bet the human brain is a kludge. -- Marvin Minsky

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