ASU researchers give memory a boost


October 23, 2007

ASU’s Center for Applied Nanoionics (CANi) has a new take on old memory, one that promises to boost the performance, capacity and battery life of consumer electronics from digital cameras to laptops. Best of all, it is cheap, made from common materials and compatible with just about anything currently on the market.

“In using readily available materials, we’ve provided a way for this memory to be made at essentially zero extra cost, because the materials you need are already used in the chips – all you have to do is mix them in a slightly different way,” says Michael Kozicki, director of CANi.

The research was conducted in collaboration with Research Center Jülich in Germany. It was published in the October 2007 issue of the journal IEEE Transactions on Electron Devices in the article “Bipolar and Unipolar Resistive Switching in Cu-doped SiO2.” The team included Christina Schindler, on loan from Germany to CANi, Sarath Chandran Puthen Thermadam of CANi, Kozicki, and Rainer Waser of the Institute for Solid State Research and Center for Nanoelectronics Systems and Information Technology in Jülich.

For some time now, conventional computer memory has been heading toward a crunch – a physical limit of how much storage can be crammed into a given space. Traditional electronics begins to break down at the nanoscale – the scale of individual molecules – because pushing electronics closer together creates more heat and greater power dissipation. As consumer electronics such as MP3 players and digital cameras shrink, the need for more memory in a smaller space grows.

Researchers have been approaching the problem from two directions, either trying to leapfrog to the next generation of memory, or refining current memory. CANi took both approaches, amping up performance via special materials while also switching from charge-based storage to resistance-based storage.

“We’ve developed a new type of old memory, but really it is the perfect memory for what’s going to be required in future generations,” Kozicki says. “It’s very low-energy. You can scale it down to the nanoscale. You can pack a lot of it into a small space.”

CANi was also able to overcome the limitations of conventional electronics by using nanoionics, a technique for moving tiny bits of matter around on a chip. Instead of moving electrons among charged particles, called ions, as in traditional electronics, nanoionics moves the ions themselves.

“We’ve actually been able to move something the size of a virus between electrodes to switch them from a high resistance to a low resistance, which is great for memory,” Kozicki says.

Most memory today stores information as charge; in the binary language of computers, this means that an abundance of charge at a particular site on a chip translated as a “one,” and a lack of charge is translated as a “zero.” The problem with such memory is that the smaller its physical size, the less charge it can reliably store.

Resistance-based memory, on the other hand, does not suffer from this problem and can even store multiple bits on one site. Moreover, once the resistance is set, it does not change, even when the power is switched off.

CANi’s previous high-performance resistance-change memory has been licensed to three companies, including Micron Technology and Qimonda, and has attracted the attention of Samsung, Sony and IBM. However, it used some materials, specifically silver and germanium sulfide, previously unused by industry and therefore required new processes to be developed.

The real advancement of CANi’s newest memory is that researchers discovered a way to use materials already common in chip manufacturing. Although “doping” – mixing silicon with small amounts of conductive materials such as boron, arsenic or phosphorus – has been common practice for years, copper in silicon dioxide was largely unheard of. In fact, it was strictly avoided.

“People have actually gone to great lengths to keep the silicon oxide and the copper apart,” Kozicki says. “But in our case, we are very interested in mixing the copper with the oxide – basically, so that it would become mobile and move around in the material.”

“Because it can move in there, we can make a sort of nanoscale switch,” he adds. “This very, very small switch can be used in memory applications, storing information via a range of resistance values.”

Industry has already shown interest in the new memory and, if all goes well, consumers could see it on the market within a few years.

“What it means is we could replace all of the memory in all sorts of applications – from laptops to iPods to cell phones to whatever – with this one type of memory,” Kozicki says. “Because it is so low energy, we can pack a lot of memory and not drain battery power; and it’s not volatile – you can switch everything off and retain information. What makes this significant is that we are using materials that are already in use in the semiconductor industry to create a component that’s never been thought of before.”

Nicholas Gerbis, ngerbis@asu.edu">ngerbis@asu.edu
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Lisa Robbins

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Homecoming game tickets selling fast


October 23, 2007

Less than 5,000 tickets remain for the college football matchup between the No. 18 California Golden Bears and the No. 7 ASU Sun Devils, on Saturday, Oct. 27 at 7:15 p.m. at Sun Devil Stadium.

Single-game tickets for the California game are priced between $25 and $40 each. Download Full Image

The Sun Devils, now 7-0 and 3-0 after a 44-20 win over Washington, have made school history reaching the #4 slot in the BCS rankings and moving to #7 on the AP Top 25 and USA Today Coaches Poll this week. Cal enters the contest 5-2, 2-2 in the Pac-10. The Golden Bears fell 30-21 to UCLA at the Rose Bowl last weekend.

ASU football Head Coach Dennis Erickson downplayed the recent standings and worries more about how injuries to key players will affect the university’s next five games.

“I like where we're at. Anytime you play seven games and win them, it's a pretty good position to be in,” says Erickson. “Obviously, injury-wise, we've had some serious injuries that have affected us a little bit, although we've played well. Ryan [Torain], of course, missing him for the year hurts us, but he's been gone in a couple other games, and Keegan has stepped up and done a nice job. With Brent Miller, hopefully we'll have him back in the next week or two.”

The Homecoming match will put great pressure on the Sun Devils on their own turf, facing Golden Bears wide receiver DeSean Jackson and quarterback Nate Longhorn, who had an ankle injury. Erickson describes the Golden Bears’ defense as “very physical.”

“They're going to play eight-man front a lot of the time to take the running game. That's just a principle of their defense. They're going to come up and stop the run, and then force you to throw it, and they're good in the secondary. So, it's going to be a real challenge for us offensively,” says Erickson. “Obviously, we've got to be able to run. Hopefully, we can make some plays in the passing game. That's going to be a real key to having some success against them.”

Saturday will be the 27th meeting between the Sun Devils and the Golden Bears. The all-time series is tied at 13 wins apiece, with ASU holding a 9-6 lead at Sun Devil Stadium. Cal has beaten Arizona State four straight times, including last season's 49-21 win in Berkeley.

Dennis Erickson is one of two first-year coaches with an unbeaten team. Coach Erickson joins Boston College's Jeff Jagodzinski as coaches who are 7-0 in their first season at their respective schools. The 7-0 start for Erickson is the best start for an ASU coach in his first season in school history.

Tickets are on sale for ASU's two other remaining home football games with USC (Nov. 22, 6 p.m.) and arch-rival Arizona (Dec. 1, 6 p.m.).

Only 700 tickets remain for the USC contest on Thanksgiving at Sun Devil Stadium.

Remaining tickets for the ASU/UA game are priced between $40 and $50 each.

Tickets can be obtained by calling the Sun Devil Athletics Ticket Office at 480-727-0000 or online at www.thesundevils.com.

Chakris">http://www.thesundevils.com">www.thesundevils.com.

Chakris Kussalanant, Chakris.Kussalanant">mailto:Chakris.Kussalanant@asu.edu">Chakris.Kussalanant@asu.edu
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