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Sunday, November 18, 2007

nanotube-based memory wafer using standard semiconductor fabrication processes.

Carbon nanotube memory coming.

Start-up Nantero has built a carbon nanotube-based memory wafer using standard semiconductor fabrication processes. This removes a significant hurdle in commercialising the seemingly exotic NRAM (non-volatile RAM) that could replace DRAM, SRAM and flash memory with a universal memory design.

A carbon nanotube has a wall just one atom wide and a diameter on one billionth of a metre. It is the building block for NRAM chips.
Production of NRAM has faced obstacles in the past, including an inability to position the nanotubes reliably across entire silicon wafers, and contamination of supplied nanotubes that made the material incompatible with hyper-clean CMOS semiconductor fabs.
Nantero has solved these problems and has demonstrated the precise alignment of 10 billion nanotubes on a single wafer manufactured in a standard semiconductor fabrication plant. The process treated the nanotube material as a fabric and used standard semiconductor fab techniques such as spincoating, lithography and etching.
It was started with OEM-sourced carbon nanotubes. These were cleansed of impurities, stray particles for example, and then layered onto a wafer with a foundation of flat tubes parallel to one another in a silicon glue, and a second upright tube layer above it, also with parallel tubes and also in silicon. The tubes can be individually bent by putting an electrical charge through them. A bent tube touching another completes a circuit by lowering electrical resistance and signals a binary one. Straighten the bent tube and you have a zero.
The aim is for Natero to licence its intellectual property to semiconductor fabrication suppliers which would then sell NRAM chips to server, PC, notebook and mobile intelligent device manufacturers.
Nantero has been doing NRAM manufacturing research work with LSI Logic, and this was switched to On Semiconductor in May this year when that firm bought the Gresham, Oregon-based fab from LSI.
In July Nantero and HP anounced they were working together on a printable memory application.
Greg Schmergel, CEO and co-founder of Nantero, said at the time: "A printable NRAM memory could be deposited on flexible substrates to enable very low cost RFID tags."
We might see the introduction of devices using NRAM chips in 2010, possibly earlier.

Oxygen makes nanotube memory
Carbon nanotubes have been used to make experimental transistors, chemical sensors and memory devices that are far smaller than anything available today. But moving from experimental prototypes to practical devices requires overcoming a large hurdle: controlling the way nanotubes grow.

Nanotubes tend to form as mixes of two types -- semiconducting and metallic -- with semiconducting the more technologically desirable. In April, 2001, IBM researchers announced they could weed out metallic nanotubes by sending enough current through a batch of nanotubes to burn up the metallic tubes but not enough to damage the semiconducting ones.

Researchers at the Max Planck Institute in Germany have come up with an alternative method of producing all-semiconducting bundles that, in addition, prepares the microscopic tubes for use in memory devices. The technique allows researchers to oxidize bundles of a few nanotubes or individual nanotubes that measure as small as 2 nanometers in diameter. A nanometer is one millionth of a millimeter, and a line of 20 hydrogen atoms spans two nanometers.

Oxidizing a bundle of nanotubes converts metallic ones to semiconducting, said Marko Burghard, a scientist at the Max Planck Institute for Solid State Research in Germany. Assemble the oxidized bundles into larger arrays and they could be "key building blocks for low-cost memories with ultra-high storage densities," he said.

The process could theoretically produce memory devices that hold one trillion bits per square centimeter, said Burghard. A trillion bits is about 31 DVDs worth of data.

The researchers hit on the process after finding that about half of nanotube bundles left in open air for several months had changed from metallic to semiconducting. This happened because oxygen atoms in the air combined with the carbon atoms in the metallic nanotubes to form a nonmetallic oxide.

The researchers were able to induce the effect by heating the nanotubes in air or treating them with oxygen plasma. A plasma is a gas whose atoms are ionized, meaning they have more or fewer electrons than normal and so can conduct electricity.

The researchers took advantage of a consequence of the oxidation process to make prototype memory devices from the oxidized tubes. The devices use a single oxidized nanotube or bundle of oxidized nanotubes as the semiconducting channel of a transistor. Data is represented by tiny electric charges of one or a few electrons stored in a defect on the surface of a nanotube produced by the oxidation. The defects are tiny clumps of amorphous, or jumbled, carbon attached to the otherwise orderly, crystalline nanotubes.

By sending three volts of electricity through the nanotubes, the researchers stored a charge in a surface defect. In electronic memory, the presence of a charge generally represents a 1 and the absence of a charge a 0. To read the 1s and 0s, the researchers sent a small current through the nanotubes to measure their conductivity. Nanotubes that harbor a stored charge are about 1,000 times more conductive than those without a charge.

Charge storage memory devices based on nanotubes were first developed several years ago; research teams at the University of Maryland and the University of Pennsylvania have recently developed experimental devices.

The Max Planck Institute memory device, however, is able to store charges longer than the other devices, said Burghard. The Maryland researchers reported a charge storage time of 1.4 hours, and the Pennsylvania researchers 16 hours. The Max Planck device is able to store charges for more than 12 days, Burghard said. Stored charge memory devices can be used as nonvolatile computer memory, which retains its data when the power is off.

The research is important work, said Vincent Crespi, an assistant professor of physics at Pennsylvania State University. "It enables a memory device to be implemented within a single nanotube plus three contacts," he said. "The charge trap seems to come along for free."

The researchers will need precise, reproducible control over the character of the charge trap before the device can be used in practical applications, Crespi added.

The researchers plan to study further the oxidation process and the nature of the charge storage defects, said Burghard. Another goal is to search for better, more controllable chemical modifications of the nanotubes, "for example, by electrochemically attaching appropriate chemical residues or small metal clusters, which could then be used for charge storage," he said.

The researchers' nanotube memory element could be used in practical applications in five to ten years, said Burghard.

Burghard's research colleagues were Jingbiao Cui, Roman Sordan and Klaus Kern. They published the research in the October 21, 2002 issue of the journal Applied Physics Letters. The research was funded by the Max Planck Society.

Some Entrepreneurs are Trying to Create an Affordable Renewable-Energy Vehicle

Could the Solar Bug Bring the Sun to the Car Market?
In the local airport parking lot, Steve Titus clicks shut the lightweight fiberglass door of his fireman-yellow "Solar Bug."

It looks like another bug -- a Volkswagen one -- that got sliced in half by a band saw, then pinched front to back by the Jolly Green Giant.

Titus straddles the saddle-style seat and revs the Hi-Torque Pancake motor. It whirs away quietly, reaching a top speed of 40 miles per hour in a few seconds.

On display at a recent alternative-car expo here, this is Titus's second and latest rendering of a solar-powered car concept. It gets up to a fourth of its 60-mile capacity from 200 watts of roof-mounted solar panels.

Titus is among those entrepreneurs trying to create and market an affordable, renewable-energy vehicle – a step beyond gas-electric hybrids.

The ranks of potential buyers for such cars are growing by leaps and bounds, say many car-industry analysts. But don't look for them on normal streets just yet, they add quickly. Limitations of batteries and solar panels -- though lessening -- are still issues, among others.

Yet "fringe markets" -- such as commuters within small towns, seniors in retirement villages, and users of industry fleets -- are in a position to drive the first sales boomlet for such cars, analysts say.

Until then, Titus and other inventor-tinkerer types are offering a peek into the future of transportation in America – well before the major car companies.

Garage tinkerers like Titus are the tip of an iceberg of innovation demonstrating the direction of the national, global trend," says Steven Letendre, professor of business, economics, and environment at Green Mountain College in Poultney, Vt., who lectures widely on the future of electric and hybrid cars and solar energy.

In fact, their ideas are increasingly showing up in the mass-market innovations of larger car companies, Letendre and others say. America's Ford Motor Co., Japan's Mazda, and Europe's Venturi Motors have all debuted prototypes at exhibitions with solar panels that boost electricity for internal lighting.

"Because of global warming, depletion of oil reserves, [and] the risks of a transportation system totally dependent on oil, there is a fundamental shift of attention towards electric and alternative power cars for more flexibility," says Letendre.

Particularly in the US, say other experts, the innovative drive is coming from places other than big companies.

"Americans are interested in innovation, and Detroit has not delivered," says Jack Hidary, chairman of, a nonprofit corporation that tries to increase the awareness and availability of clean technology. "It is people like Titus in their garages who are the ones making innovation happen."

Titus, who is based in Bozeman, Mont., has 25 years of experience bringing alternative-power products to market, working with more than a dozen businesses that range from medical equipment to lasers. About seven years ago, he got tired of driving to the gas pump, paying high prices, and watching the geopolitical clashes over oil in the Middle East.

He began working on designs for a car in his spare time, and 18 months ago, he quit his job at Big Sky Laser Technologies to work on his project full time. He has spent $100,000 -- "all the savings from my retirement account," he says -- experimenting with body design, braking, batteries, lighting, controls, and safety features.

After exhibiting his latest prototype, he has 53 orders, and seven dealers have signed up to sell his cars. Multiple-unit buyers such as the Walt Disney Co. and the government of Aruba have also expressed significant interest. The 900-pound two-seater is currently being offered for about $15,000.

"Last year, people told us they wanted a cooler body, sexier wheels, better seating, more mileage, and faster speeds," says Titus. "We gave it to them, and interest is exploding."

Of course, challenges remain in selling the cars to a broader audience. The distance that such a vehicle can travel in one trip is well under 100 miles. And although the top velocity for the cars has increased, they still don't reach highway speeds. In fact, for the solar power to work best, the vehicle needs to travel at a low or medium speed. Other hurdles include how to manufacture and mass-market the vehicles.

Still, of 150 exhibits at the Alternative Car and Transportation Expo last month in Santa Monica, Calif., the Solar Bug was the "highlight of the show," according to Ron Gompertz, founder of Eco Auto Inc., a car dealer.

Some industry experts see a growing potential for such entrepreneurial ventures. "The interest in photovoltaic use in cars is making great headway in other countries such as Japan and Germany, but is still somewhat behind in the US, where consumers still want quite a bit of power and size and comfort," says Denise Chiavetta, leader of the technology foresight program at Social Technologies, a global research firm.

But some US consumers can hardly wait for more innovation. Take Cara Lee, an architect in Santa Monica who has owned a gas-electric hybrid Toyota Prius for six years. She now wants something that uses no gas.

"I like that this [Solar Bug] costs very little to buy and run, parks easily, can take me back and forth to work, and do quick errands," she says. "But mostly, I like that it charges by the sun."

Ghostbusters" video game

Ghostbusters 3': Gamers to Get 'Slimed' in 2008.
Apparently the original three Ghostbusters -- Bill Murray, Dan Aykroyd and Harold Ramis -- "ain't afraid of no ghosts." The three are slated to join forces to create a "Ghostbusters" video game set for release in fall 2008.

Ghostbusters The Game," a collaboration between Sierra Entertainment and Sony Pictures, allows players to join the team as it ghost hunts its way across Manhattan.

In development for the past two years, the game's developer worked hard to bring the original film's cast to the table, according to Tom Stratton, a senior global public relations manager at Sierra.

The Game's Not Over for Ghostbusters

Maybe you thought that you would never hear Bill Murray say the words “He slimed me,” again but it looks like you will, at least if you play video games. Work has begun on another “Ghostbusters” but this time the story will happen on video game consoles and not at movie theaters.

Reuniting are the film’s stars including Bill Murray, Dan Ackroyd, Harold Ramis and Ernie Hudson as the four heroes. Also coming along for the digital ride are Annie Potts (the Ghostbusters’ secretary/receptionist), William Atherson (the health inspector that caused them grief in the first movie) and Brian Doyle Murray, Bill’s brother.

Unfortunately no Sigourney Weaver and Rick Moranis, but we’re guessing that there might be appearances by the team’s ghostly mascot Slimer and maybe even the Stay Puft Marshmallow Man.

Ackroyd and Ramis have been hired to write the video game storyline to ensure that it falls in step with the quality of the two movies. The action will take place sometime in the early 1990s, after the time of “Ghostbusters 2”, and find the supernatural squad the only line of defense against a plague of ghouls marauding New York City.

Vivendi Universal will release the game on the PS2, PS3, Wii, Xbox 360, Nintendo DS and for the PC in the fall of 2008. If the game is a hit (and everyone is hoping that people still want to get slimed) expect to see more “Ghostbusters” games.

Heck, it might even convince Murray to come back and don the brown jumpsuit one final time in a “Ghostbusters 3”. Ackroyd and Ramis have a movie script ready to go that would take the guys straight to Hell.

"From the beginning, it was very important that talent be involved with this. It was a goal for everybody [that] it was going to be as authentic to the original films," Stratton told

The original three will all lend their voices to the game, and Aykroyd and Ramis will resume the writing duties they shared in the 1984 megahit "Ghostbusters" and its 1989 sequel as they pen the game's events.

Ernie Hudson, who played Winston, and Annie Potts, who played the crew's receptionist, will also be featured in the game. As of now, Sigourney Weaver, who played the romantic lead in both films, isn't signed on to participate.

"We're doing our best to get everybody involved," Stratton said.

Sierra's foray into the video game version of movies, like "Scarface," prompted the game's development.

"We were looking at the portfolio of really hot iconic film properties. 'Ghostbusters' was in the top five -- up there with 'Scarface,'" Stratton said. "It made for a great opportunity for us."

The game will be released on all major platforms.

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