Carbon Nanotube Computers

Technology Review ^ | 05/25/06 | Kevin Bullis

[PeaceBeWithYou]

Researchers at IBM have overcome an important obstacle to building computers based on carbon nanotubes, by developing a way to selectively arrange transistors that were made using the carbon molecules. The achievement, described in the current issue of Nano Letters, could help make large-scale integrated circuits built out of carbon nanotubes possible, leading to ultrafast, low-power processors.

For decades, the size of silicon-based transistors has decreased steadily while their performance has improved. As the devices approach their physical limits, though, researchers have started looking to less conventional structures and materials. Single-walled carbon nanotubes are one prominent candidate -- already researchers have built carbon nanotube transistors that show promising performance (see The Nanotube Computer). According to estimates, carbon nanotubes have the potential to produce transistors that run 10 times faster than even anticipated future generations of silicon-based devices, while at the same time using less power.

But so far research in the field has hit a roadblock: not being able to control the placement of nanotube transistors, making it impossible to build complex integrated circuits. "The way most [nanotubes transistors] are made now, nanotubes are randomly dispersed on a surface in solution, then source and drain contacts are randomly printed using lithography, and then you search around until you find by chance a tube that goes between a source and a drain," says James Hannon, one of the researchers involved with the work at IBM's T.J. Watson Research Center in Yorktown Heights, NY.

To gain control over the arrangement of transistors, the IBM researchers coated the nanotubes with molecules that bind only to patterns of metal oxide lines on a surface, and not to the areas in-between.

To make working transistors, the researchers laid down lines of aluminum using a lithography technique. These wires serve as the gates that turn the transistors on and off. They then oxidized the aluminum to form a thin aluminum oxide layer on top of the wires, which acts as both a dielectric and the material to which the nanotubes will bind. After applying carbon nanotubes in solution and allowing them to bind to the aluminum oxide, the researchers deposited palladium leads perpendicular to the aluminum/aluminum oxide wires. These leads crossed over the nanotubes, becoming the source and drain of the transistor.

While developing this method of organizing nanotube transistors is an important step, much work remains to be done before commercial processors will be available. For one thing, exploiting the full potential of nanotube transistors will require improving the leads, possibly by using nanotubes in place of the palladium wires.

But perhaps a more pressing problem is finding reliable and inexpensive ways to isolate different types of carbon nanotubes. Current fabrication techniques produce a mix of nanotubes with different sizes and electronic properties, not all of which will work well in integrated circuits.

Because of these challenges, the first applications of carbon nanotube transistors will probably not be as high-performance processors, Hannon says, but highly sensitive sensors that work even with a mix of different nanotubes.

Meanwhile, others are developing devices that don't rely on nanotubes' high-end electrical properties, but rather on features such as their strength and flexibility. This skirts the need both to sort and to individually arrange the nanotubes. The Woburn, MA-based company Nantero, for example, takes advantage of nanotubes' strength and flexibility to make memory devices. "We use [nanotubes] as electromechanical devices, so we just bend them up and down to represent zeros and ones," says Nantero CEO Greg Schmergel. In this application, clusters of nanotubes rather than single tubes can be used, so they can be patterned using lithography.

Eventually, Schmergel says, nanotubes could replace every part of semiconductor devices by using all of the tubes' features. "Nanotubes have quite a number of unique properties all combined in one material. They can replace memory, logic, the interconnect, ultimately they can replace everything in the chip, so it definitely makes sense to pursue all of those angles," he says.

Selectively placing carbon nanotubes (thin green line in inset enlargement) for transistors could lead to ultrafast, low-power computers. In the larger image, the vertical line is an aluminum oxide wire and horizontal lines are sources and drains. (Courtesy of IBM.)

[PeaceBeWithYou]

Big step towards smaller, faster, more efficient, computers and more.

Enjoy.

[familyop]

...good post. Many other changes will accompany the new computers, when they are on the market.

[Echo Talon]

i'm still waiting for holographic drives(storage)... remember that?

[misterrob]

2010 is when current memory technology is supposed to hit its limit. Logic and processing chips not likely until 2015.

The manufacturing tool sets are coming to market and while CNTs are known to have quality issues the direction forward looks good.

[Lexinom]

What's a transistor? (just kidding)

Seriously, I've heard about many techtologies over the years: Germanium, gallium-arsenide. This particular one seems to imply a completely different manufacturing process.

One of the limitations of traditional N- and P- doped silicon is the atomic size difference between boron (+) and phosphorus (-). Even though CMOS stands for complimentary metal oxide semiconductor, the P-channel devices run at only about half the speed as their N- counterparts. This is why, in the early days before CMOS dominance, it was NMOS devices that were typically seen in early IC memory and microprocessor applications. Very few IC's employed PMOS, and all without exception that I can think of were linear, analog applications. I never quite understood why - cleaner signals maybe?

The key will be attaining a high yield rate with an inexpensive manufacturing process. The article hints at one of the upcoming challenges to this:

Current fabrication techniques produce a mix of nanotubes with different sizes and electronic properties, not all of which will work well in integrated circuits.

[Bommer]

i'm still waiting for holographic drives(storage)... remember that?

Getting close, Check this out

Fancy a Million-Gigabtye Hard Drive?
May 11th, 2006 | Posted in Misc Portable Technology by Leon Huang | Source

 HDD, Storage, Computer, Tech, Technology

Researchers have finally found a way to create storage devices that are capable of storing millions of gigabytes of data. With the use of ferroelectric, the researchers from Drexel University and University of Pennsylvania are able to squeeze 12.8 million gigabytes of information into a cubic centimeter. Very amazing indeed.

Until recently, researchers were not able to find a method of stabilizing ferroelectricity on the nano-scale. It was this group of talented researchers that found out that water is in fact the answer to their problem. It has to do with the hydroxyl (OH) ions molecules found in water, which are capable of screening the charges.

Imagine the possibility of million-gigabyte hard drives. The amount of disk space might seem excessively generous, but I trust that when these drives become a reality, applications that truly leverage the obscene amount of space will start to sprout.

However, several researchers have suggested that significant challenges still lie ahead, such as methods of assembling the nanowires densely and efficiently reading and writing data to and from the nanowires.

[Echo Talon]

WoW i'll take 4 in a RAID 0+1 configuration... :)

[Erasmus]

I always knew that transistors were a flash in the pan and that tubes would make a comeback some day.

[Erasmus]

Actually, the first calculators and similar devices were PMOS. I don't know the details, but I think the process was easier. Also, PMOS could run at higher voltages, allowing them to drive vacuum fluorescent and neon-discharge based displays directly, whereas NMOS or CMOS could not (easily).

[TexasTransplant]

Way too Cool.

I haven't even stressed the Pute I have and it's OLD

TT

[tophat9000]

Man I haven't dealt with this stuff since computer school learning semi conductor theory and "hole flow"...Good Stuff

(O God ! I am a geek !:O ;)

[SamAdams76]

Consider that the computer revolution is still in its infancy.

Remember how citizens of the 1820s made all that fuss over their steam engines and cotton gins? That was the infancy of the industrial revolution and yet people of the time marveled at the "modern" age they were living in some thought that either the human race had reached the limits of its potential or that the human race had gotten "too big for its britches" and was displeasing God.

I am old enough to remember when hand-held calculators were a big deal back in 1974. I was one of the first ones to take one into my 6th grade class and all the other kids (including my teacher) crowded around my desk to see this marvel for themselves. This calculator not only did the four basic math functions but it had a percentage and square root key as well. This was big stuff back then. My teacher had me input some "complicated" problems to try to fool it but it spit back the right answer, always. So long as the answer didn't consist of more than 8 digits. Also, this calculator had bright red LEDs and sucked up batteries faster than laptops do today.

Now flash forward about 20 years to the day I brought home my first home computer. This was only about 12 years ago. This computer costed nearly $3,000 and it sported 4MB of RAM, a 20MHz 486 processor and a whopping 129MB hard drive. It also had a 2400bps modem that I hooked up to Prodigy with (at $3.60 an hour). This was before most of us even knew what the Internet was.

This was only 12 years ago!

Today, I have many computers in the house including the one I am typing this out on. This computer has 2 gigabytes of RAM, two 300GB hard drives, a 3 gigahertz processor and a 21 inch LCD screen. With a Bose speaker system that would blow my 1993 era home stereo away. My entire record collection (some 1200 albums and 15,000 songs) takes up maybe a quarter of one of my two hard drives.

One can only guess what a typical computer of 12 years from now will be like. I'm guessing that storage space will be measured in terrabytes and it will be possible to store pretty much every book and piece of music ever written for starters.

[grey_whiskers]

However, several researchers have suggested that significant challenges still lie ahead, such as methods of assembling the nanowires densely and efficiently reading and writing data to and from the nanowires.

Or trying to sift through all that [bad word] data.

Cheers!

[indthkr]

"... much work remains to be done before commercial processors will be available."

An understatement to be sure.

Carbon nanotubes and bucky balls are interesting things, but as one nanotech researcher pointed out at a recent lecture, they have been around a long time.

It's basically soot! You can make your own nanotubes on Memorial Day when you get distracted and start incinerating those burgers on the grill. If you happen to have a Scanning Electron Microscope handy (someone I know has one in his garage), you can marvel at your creations. Maybe you'll get amazingly lucky and a few will land between the filaments of your wire grill brush & make carbon nanotube resistors!

[GEC]

bump to read.

[timer]

Our technology is exploding so fast we'll be ahead of some alien races soon. Is the movie INDEPENDENCE DAY a metaphor for US as the invading aliens? Seriously though, ever thought about color wavelengths as pixel "binary" storage vs the ancient 01100111 bit/bytes of morse code? It comes from the ENIAC days of high thermal noise in vacuum tubes : on/off as max signal. How many different colors can be expressed in a TV pixel, then 500 pixels/line and 500 lines = a BIG number expressed in a single TV picture. Then there's sound frequencies, odors; to wit, WE are still the premier general purpose computer walking around, why not copy a succesful model, instead of dit-dah-dit Q-bits, nanotubes?

[Bommer]

Yeah I remember thinking I was hot sh!t with my 486 and 16 megs of ram on my 30 meg hard drive!

[staytrue]

I don't understand why we need more computing power than we already have.

Just write better software and the computers will speed up by a factor of 3 or 4 and I don't need any more power than I have now.

[Xenophon450]

For complicated science calculations that can last days on end, or maybe better servers that can handle many more clients at once, games, games, games, HD video eats harddrive space like a skinny guy on a buffet (They can EAT!!).

[Prophet in the wilderness]

As Spock from Star Trek wold say " Hhhmmm ... Fascinating "

So ? what you are you saying.. is ? instead of using the binary code of 1s and 0s ( 0110011100011110000 ) as in used in computers today, use color wave or sound wave lenghts as some kind of pixel or pitch " Binary code " ?