The Carbon Nanotube Transistor and why you should care...

Watching the dawn of a new technology is sure exciting. When I was a student at UMASS I remember hearing about the invention of the blue/violet LED, which was followed by the white LED, which is just a blue/violet LED painted in phosphors. That was well less than two decades ago. I knew it would be widespread technology back then, and it has been amazing to see how fast it went from lab to mass production.

LEDs have started to change the whole way the world looks, and will continue to do so. Watch an old movie wherever they show lighting -- all those neon signs in shop windows, the bulb-behind-plastic-button control panels in the old scifi movies -- you can instantly tell the footage is old before you even see an actor on the screen. It just feels old.

Here's another technology that will change the way the world looks, even though you'll probably never actually see one face to face.

http://www.eetasia.com/ART_8800561469_480200_NT_b2dceaa5.HTM



What they are saying is they have figured out how to make a neat row of carbon nanotubes -- lots of them lined up side by side. While a few of them lined up side by side can help make much smaller, more powerful, and less power hungry computers, lots of them lined up in a row can make a high current device called a FET.

So what is a "high current FET?"

Let's put it this way. Every computer, compact fluorescent bulb, uninterruptible power supply, audio-visual gadget -- just about everything that has advanced electronics in it, has to convert the power from the plug into a more digestible form. Even in a laptop powered on a battery, still, the power has to be smoothed and chewed, many times, because different parts of the computer have different needs. Inevitably, some of it gets wasted in the process.

These days we use a hybrid transistor called and IBGT for that. These days, in off the shelf equipment, we waste 10 to 15% of the power we use every time we have to convert it.

Before that we had the plain old FET. Back then we used to waste 15 to 25% of the power we used.

Back in what seems like ancient times, we used very simple transformer and rectifier circuits, and many times something called linear regulators. Well let's just say we wasted a whole lot of electricity back then.

These new FETs will not be just a nudge up to 5-10%, but two steps up from where we are now. We'll be under 5% wasted power when these hit the market. This one invention will shave a few percent of the total U.S. residential energy consumption.

Before you say "meh, just a few percent?" consider this:

If we are going to have a "smart grid" to allow distributed power generation from individually and community owned renewable resources, we're going to be doing a whole lot more power converting -- back and forth as power is moved up and down power lines instead of just going down. Somewhere in some board room, some bean counter is deciding how fast a power company can smarten up their grid. Among the numbers he is crunching is the amount of energy that is wasted if a power company borrows electricity for ten minutes from a plug-in hybrid car parked in joe six pack's garage. It will actually be a pretty important number in the equation...

By the way. Here's a word you'll be hearing a lot as carbon nanotubes become more and more important -- "chirality." Here's what that is. Take a two cans of soda and a sheet of bubble wrap. Cut a strip 3 bubbles wide from the bubble wrap. Cut another strip 4 bubbles wide. Now wrap one strip around each soda can snugly in a spiral, lining up the bubbles at the edges. See how the rows of bubbles line up differently? That's chirality.

As it turns out you can grow carbon nanotubes with a lot of different chiralities. Some of them will behave like a metal wire, and others will behave like a glass wire. Within those two groups there are other more subtle differences in the properties of nanotubes -- all just because they spiral around in different ways from one another. Figuring out how to manipulate and exploit these differences is one of the fascinating things scientists are up to these days.

And even though you can't even see the stuff they are working on with visible light, no matter how powerful a microscope you have, it's that work that enables the stuff you use today, and what tomorrow's skylines, streets, sidewalks, and rooftops will look like.

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just thot you might want to know

I might not be the only one that it bugs . . .

I've been sort of following the development of them from the beginning. I love hearing about them, and what can be done with them, but I'm impatient to actually see them in everyday use in various capacities. If I can last, what, 5? 10? 15? more years, I want to just because of nanotubes. If I were young and science-oriented, that's the field I'd go into. The possibilities are endless.

Thanks for the information.

This is going to be very interesting. And I mean the conversations I expect to have with my old electronics dad. He grew up with tubes. Watched Shockley and Bardeen. Worked in the chip manufacturing business. And is a diode nut.

This goes beyond science. The world is maturing in a way that will enable us to move to the next level of consciousness. And the transistor is what made the internet possible. Argh, it's late and I'm off to bed.

When we refused to go back into a Silicon Valley building after a major earthquake there.

He kept hollering "The earthquake is over. It's done. Get back to work!"

We were all like, "Well, hasn't he ever heard about after shocks?"

Besides which, our jobs depended on having a working phone lines, and the quake had brought the phones to a halt.

We're all human. A lot of nutjobs have benefited society in great ways. I've always said that everyone has something genius and something evil within them. This is why I believe in forgiveness and non judgment.

Shockley did something rotten to some black students in his class at Stanford. It's probably on his Wiki page.

That's funny hearing your story.

Earthquake aftershocks. Or some dimension of the human psyche. We had all just been under our desks, watching the giant 4 ton air conditioners over our desks swinging precariously back and forth, wondering when they would free fall onto our desks. (Morgan Hill earthquake, 1984)

That summer I moved away from Silicon Valley. For good.

with something that's 20% more efficient - and the car goes 20% farther. And is 20% more practical.

I like it :thumbsup:

k&r

Making the controller 20% more efficient will have very little effect on electric car distance. The overall efficiency is something like 90%. So 20% improvement of 10% would yield 92% efficiency.

I love learning new things :)

From technology that's made by taking a larger item and removing bits to a technology that's grown. Chemistry and engineering.

http://michaelgr.com/2009/01/31/is-graphenegraphane-the-future-of-cpus/

A hypothetical example for this is graphane (7), a wide-gap semiconductor, in which hydrogen is bonded to each carbon site of graphene. Here we show that by exposing graphene to atomic hydrogen, it is possible to transform this highly-conductive semimetal into an insulator.

and also
http://physicsworld.com/cws/article/news/37600

“The modern semiconductor industry makes use of the whole periodic table, from insulators to semiconductors to metals. But what if a single material could be modified so that it covers the entire spectrum needed for electronic applications?” added Geim. “Imagine a graphene wafer with all interconnects made from highly conductive, pristine graphene whereas other parts are modified chemically to become semiconductors — and work as transistors — or become insulators.”

I didn't see any reference to the properties improvement in a Carbon Nanotube FET. Or perhaps a much improved transition?
And without significant reduction in rectifier diode drop, I don't think you will see anything close to what is implied. At least not in power conversion. Now if the fet charge current could is significantly lower this could be a boom for IC density to levels we have yet to dream of.

It's a new field, so by the time someone publishes a paper assessing limits on them, someone else has broken through the barriers that that person was taking as given.

These guys seem pretty optimistic:

http://www.azonano.com/details.asp?ArticleID=543

Of course in reality we already have 95% efficient power supplies using current technology, just not manufacturers willing to integrate the additional cost involved into their sticker prices :-) Hopefully someday we'll reach a point where both patent holders and device builders can charge/pay reasonable prices instead of all the bridge trolling and fare skipping that pervades the market, and where the first question out of a consumer's mouth is "yeah that's how much it costs to buy, now what does it cost to run?"

As far as diode drop goes, it's really in low voltage supplies where that is most important, and there you can do a syncronous rectification bypass.

Of course the best way to figure out where the "waste bottlenecks" are in current state of the art is to break open a brand new energystar-approved power supply or laptop and look where the biggest heat sinks are :evilgrin: but I don't have anything built after about 2002 that I'm willing to crack open at the moment.

when you take the product of serial losses? As you say, these things happen at various levels, from the grid on down sub-components in an electronic device. So, a hypothetical improvement at all levels from 15% to 5% becomes the difference between (0.85)^n, and (0.95)^n. I don't know what (n) is, but even for n=2, the difference is pretty substantial.