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Stanford Report — Dec 18,`07 — Dan Stober writes an in-depth article on Stanford’s nanowire battery at Stanford news service.

Stanford researchers have found a way to use silicon nanowires to reinvent the rechargeable lithium-ion batteries that power laptops, iPods, video cameras, cell phones, and countless other devices.

The new version, developed through research led by Yi Cui, assistant professor of materials science and engineering, produces 10 times the amount of electricity of existing lithium-ion, known as Li-ion, batteries. A laptop that now runs on battery for two hours could operate for 20 hours, a boon to ocean-hopping business travelers.

“It’s not a small improvement,” Cui said. “It’s a revolutionary development.”

The breakthrough is described in a paper, “High-performance lithium battery anodes using silicon nanowires,” published online Dec. 16 in Nature Nanotechnology, written by Cui, his graduate chemistry student Candace Chan and five others.

The greatly expanded storage capacity could make Li-ion batteries attractive to electric car manufacturers. Cui suggested that they could also be used in homes or offices to store electricity generated by rooftop solar panels.

“Given the mature infrastructure behind silicon, this new technology can be pushed to real life quickly,” Cui said.

The electrical storage capacity of a Li-ion battery is limited by how much lithium can be held in the battery’s anode, which is typically made of carbon. Silicon has a much higher capacity than carbon, but also has a drawback.

Silicon placed in a battery swells as it absorbs positively charged lithium atoms during charging, then shrinks during use (i.e., when playing your iPod) as the lithium is drawn out of the silicon. This expand/shrink cycle typically causes the silicon (often in the form of particles or a thin film) to pulverize, degrading the performance of the battery.

Cui’s battery gets around this problem with nanotechnology. The lithium is stored in a forest of tiny silicon nanowires, each with a diameter one-thousandth the thickness of a sheet of paper. The nanowires inflate four times their normal size as they soak up lithium. But, unlike other silicon shapes, they do not fracture.

Research on silicon in batteries began three decades ago. Chan explained: “The people kind of gave up on it because the capacity wasn’t high enough and the cycle life wasn’t good enough. And it was just because of the shape they were using. It was just too big, and they couldn’t undergo the volume changes.”

Then, along came silicon nanowires. “We just kind of put them together,” Chan said.

For their experiments, Chan grew the nanowires on a stainless steel substrate, providing an excellent electrical connection. “It was a fantastic moment when Candace told me it was working,” Cui said.

Cui said that a patent application has been filed. He is considering formation of a company or an agreement with a battery manufacturer. Manufacturing the nanowire batteries would require “one or two different steps, but the process can certainly be scaled up,” he added. “It’s a well understood process.” More at Stanford.edu

East Fishkill, NY and TOKYO, Japan –December 18, `07 — IBM and Toshiba today announced that they have entered into a joint development agreement on 32nm bulk complementary metal oxide semiconductor (CMOS) process technology.

Since December 2005, IBM and Toshiba have collaborated on fundamental advanced research related to semiconductor process technologies at the 32nm technology generation and beyond at the research facilities in Yorktown and Albany, New York. Building on the success of this ongoing research collaboration, the two companies have agreed to extend the scope of the joint development work to now include 32nm bulk CMOS process technology.

Under the new agreement, Toshiba joins a six company IBM Alliance for 32nm bulk CMOS process technology development based in East Fishkill, New York.

Through this collaboration IBM and Toshiba plan to accelerate development of next-generation technology to achieve high-performance, energy-efficient chips at the 32nm process level, and to enhance the companies’ leadership in the global semiconductor industry.

“This agreement caps a year of extraordinary momentum for IBM and its semiconductor Alliance Partners,” said Gary Patton, vice president for IBM’s Semiconductor Research and Development Center. “In 2008 we’ll continue to strive to collectively deliver the industry breakthroughs and manufacturing milestones that come from talented engineers and semiconductor experts working in an open, collaborative environment with access to world class R&D facilities such as UAlbany NanoCollege’s Albany NanoTech complex.” More at Toshiba.

TOKYO, Japan — Dec 13, ‘07 — Toshiba today announced that it has achieved breakthroughs in three major basic technologies for 32nm generation system LSIs and beyond.

The advances are a major advance in metal gate electrode; a new structure and process technology for low resistance contacts that reduce contact resistance; and a technology for improving performance by changing the surface orientation of the silicon substrate. The new breakthrough will pave the way to 32nm LSIs and improve process efficiencies.

The three technologies were introduced at the IEDM (International Electron Devices Meeting) conference held at Washington DC, as major candidates for basic technologies for use in 32nm generation system LSIs and beyond. Toshiba will continue their development and optimization and aim for mass production in the first half of FY2010.

In developing the improved, new metal gate, Toshiba has realized a simplified manufacturing process technology that employs nickel silicide, a common material for both nMOS and pMOS transistors in a ratio of 1:3, respectively, and introduces an aluminum layer only in the nMOS gate.

For the low resistance contact, Toshiba employed a metal material in the source/ drain region, reducing contact resistance to a quarter in the nMOS side. The base electrode material is the same for both the nMOS and pMOS in pairs, and low-Schottky-barrier metal suitable for each type MOS transistor is segregated at interface of base material. The manufacturing process is simplified.

System LSI integrates CMOS elements, nMOS transistors and pMOS transistors. Therefore an optimized process is required. These new two technologies enhance performance and also contribute to an efficient manufacturing process. More at Toshiba.

Applied double tunneling layer to realize 100 gigabit density.

TOKYO, Japan — Toshiba Corporation on Wednesday, Dec 12, announced that it has developed a new double tunneling layer technology applicable to future 10nm generation flash memories. This elemental technology opens the way for memory devices with densities of over 100 gigabits in the 10nm generation, which lies four generations ahead. The technology was today announced at the IEDM (International Electron Devices Meeting) held at Washington DC.

Toshiba developed a tunnel layer, which controls in and out of electron, in the SONOS (Silicon Oxide Nitride Oxide Semiconductor) type device structure, a memory structure that holds electrons in the nitride layer in the gate insulator.

The new structure sandwiches a 1.2 nm silicon nanocrystals layer between the 1nm thickness oxide films, achieving long-time data retention and high speed writing and data deletion at the same time, using the natural characteristic that resistance changes with changes in gate voltage. As the new tunnel layers are thinner than early version SONOS element tunnel layers, it is easier to migrate to advanced devices with finer lithography.

Toshiba also increased the saved electrons amount by changing the nitride film from Si3N4 to Si9N10, a material that contains more silicon, and optimized such aspects of the element structure as channel impurity concentration. The prototype has realized and maintained equivalent to over 10 years performance.

Toshiba is investigating various technologies for future advanced memories, including 3D structures, and believes that realizing operation in the 10nm generation with its new double tunneling layer technology is a step forward to future practical devices. More at Toshiba.

Nanotubes may have high-tech applications, study involving UCR engineers reports.

RIVERSIDE, Calif — Dec 07, ‘07 — Two engineers at the University of California, Riverside are part of a binational team that has found semiconducting nanotubes produced by living bacteria – a discovery that could help in the creation of a new generation of nanoelectronic devices.

The research team believes this is the first time nanotubes have been shown to be produced by biological rather than chemical means. It opens the door to the possibility of cheaper and more environmentally friendly manufacture of electronic materials.

Study results appear in today’s issue of the early edition of the Proceedings of the National Academy of Sciences.

The team, including Nosang V. Myung, associate professor of chemical and environmental engineering in the Bourns College of Engineering, and his postdoctoral researcher Bongyoung Yoo, found the bacterium Shewanella facilitates the formation of arsenic-sulfide nanotubes that have unique physical and chemical properties not produced by chemical agents.

“We have shown that a jar with a bug in it can create potentially useful nanostructures,” Myung said. “Nanotubes are of particular interest in materials science because the useful properties of a substance can be finely tuned according to the diameter and the thickness of the tubes.”

The whole realm of electronic devices which power our world, from computers to solar cells, today depend on chemical manufacturing processes which use tremendous energy, and leave behind toxic metals and chemicals. Myung said a growing movement in science and engineering is looking for ways to produce semiconductors in more ecologically friendly ways.

Two members of the research team, Hor-Gil Hur and Ji-Hoon Lee from Gwangju Institute of Science and Technology (GIST), Korea, first discovered something unexpected happening when they attempted to remediate arsenic contamination using the metal-reducing bacterium Shewanella. Myung, who specializes in electro-chemical material synthesis and device fabrication, was able to characterize the resulting nano-material.

The photoactive arsenic-sulfide nanotubes produced by the bacteria behave as metals with electrical and photoconductive properties. The researchers report that these properties may also provide novel functionality for the next generation of semiconductors in nano- and opto-electronic devices.

In a process that is not yet fully understood, the Shewanella bacterium secretes polysacarides that seem to produce the template for the arsenic sulfide nanotubes, Myung explained. The practical significance of this technique would be much greater if a bacterial species were identified that could produce nanotubes of cadmium sulfide or other superior semiconductor materials, he added.

“This is just a first step that points the way to future investigation,” he said. “Each species of Shewanella might have individual implications for manufacturing properties.” More at University of California, Riverside.

YORKTOWN HEIGHTS, NY - Dec 06, 2007 — Supercomputers that consist of thousands of individual processor “brains” connected by miles of copper wires could one day fit into a laptop PC, thanks in part to a breakthrough by IBM scientists announced today.

And while today’s supercomputers can use the equivalent energy required to power hundreds of homes, these future tiny supercomputers-on-a-chip would expend the energy of a light bulb.

In a paper published in the journal Optics Express, the IBM researchers detailed a significant milestone in the quest to send information between multiple cores — or “brains” — on a chip using pulses of light through silicon, instead of electrical signals on wires.

The breakthrough — known in the industry as a silicon Mach-Zehnder electro-optic modulator — performs the function of converting electrical signals into pulses of light. The IBM modulator is 100 to 1,000 times smaller in size compared to previously demonstrated modulators of its kind, paving the way for many such devices and eventually complete optical routing networks to be integrated onto a single chip. This could significantly reduce cost, energy and heat while increasing communications bandwidth between the cores more than a hundred times over wired chips.

Today, one of the most advanced chips in the world — IBM’s Cell processor which powers the Sony Playstation 3 — contains nine cores on a single chip. The new technology aims to enable a power-efficient method to connect hundreds or thousands of cores together on a tiny chip by eliminating the wires required to connect them. Using light instead of wires to send information between the cores can be 100 times faster and use 10 times less power than wires.

IBM’s optical modulator performs the function of converting a digital electrical signal carried on a wire, into a series of light pulses, carried on a silicon nanophotonic waveguide. First, an input laser beam is delivered to the optical modulator, which acts as a very fast “shutter” which controls whether the input laser is blocked or transmitted to the output waveguide.

When a digital electrical pulse arrives from a computer core to the modulator, a short pulse of light is allowed to pass through at the optical output. In this way, the device “modulates” the intensity of the input laser beam, and the modulator converts a stream of digital bits (“1”s and “0”s) from electrical signals into light pulses.

The report on this work, entitled “Ultra-compact, low RF power, 10 Gb/s silicon Mach-Zehnder modulator” by William M. J. Green, Michael J. Rooks, Lidija Sekaric, and Yurii A. Vlasov of IBM’s T.J.WatsonResearch Center in Yorktown Heights, N.Y. is published in Volume 15 of the journal Optics Express. This work was partially supported by the Defense Advanced Research Projects Agency (DARPA) through the Defense Sciences Office program “Slowing, Storing and Processing Light”.More at IBM.

Single carbon nanotube is fully functional radio, receiving music over standard radio bandwidth. Oct 31, ’07 — National Science Foundation – 

Harnessing the electrical and mechanical properties of the carbon nanotube, a team of researchers has crafted a working radio from a single fiber of that material. 

Fixed between two electrodes, the vibrating tube successfully performed the four critical roles of a radio–antenna, tunable filter, amplifier and demodulator–to tune in a radio signal generated in the room and play it back through an attached speaker.  

Functional across a bandwidth widely used for commercial radio, the tiny device could have applications far beyond novelty, from radio-controlled devices that could flow in the human bloodstream to highly efficient, miniscule, cell phone devices.  

Developed at the National Science Foundation’s (NSF) Center of Integrated Nanomechanical Systems, a research team led by Alex Zettl of the University of California at Berkeley announced the findings online on Oct. 31, 2007 (http://pubs.acs.org/journals/nalefd/index.html). The findings are scheduled to be printed in Nano Letters in November.  

“This breakthrough is a perfect example of how the unique behavior of matter in the nanoworld enables startling new technologies,” says Bruce Kramer, a senior advisor for engineering at NSF and the officer overseeing the center’s work. “The key functions of a radio, the quintessential device that heralded the electronic age, have now been radically miniaturized using the mechanical vibration of a single carbon nanotube.” 

The source content for the first laboratory test of the radio was “Layla,” by Derek and the Dominos, followed soon after by “Good Vibrations” by the Beach Boys. 

The new device works in a manner more similar to the vacuum tubes from the 1930s than the transistors found in modern radios. In the new radio, a single carbon fiber a few hundred nanometers (billionths of a meter) long, and only a few molecules thick, stands glued to a negatively charged base of tungsten that acts as a cathode. Roughly one millionth of a meter directly across from the base lies a positively charged piece of copper that acts as an anode.  

Power in the form of streaming electrons travels from an attached battery through the cathode, into the nanotube, and across a vacuum to the anode via a field-emission tunneling process.  

The researchers believe it would be easy to produce such nanotube radios for receiving signals in the 40-400 megahertz range, a range within which most FM radio broadcasts fall.  

The researchers fine tune the nanoradio to a frequency, akin to a channel, by using the electrostatic field between the cathode and anode to tighten or loosen the nanotube, a process the researchers relate to the tightening or loosening of a string on a guitar. According to Zettl, the sensitivity of the nanotube radio can be enhanced by attaching an external antenna or by using an array of nanotubes that maintain the extremely small size. 

Adds Bruce Kramer, “The application of a fully functioning radio receiver less than 50 millionths of an inch in length and one millionth of an inch in diameter potentially allows the radio control of almost anything, from a single receiver in a living cell to a vast array embedded in an airplane wing. More at NSF.

SEOUL, South Korea (AP) — Samsung Electronics Co. said Tuesday it has developed a more advanced flash memory chip that will allow increased data storage in digital products such as music players.

Samsung, the world’s largest maker of computer memory chips, unveiled a 64-gigabit NAND flash memory chip based on finer process technology using circuit elements that are 30 nanometers wide. A nanometer is one-billionth of a meter; a human hair is about 80,000 nanometers across.

Samsung touted the development of the chip as a world first and said the new chip marks the eighth straight year that memory density has doubled and the seventh straight year that the nanometer scale has improved for NAND flash.The company said it plans to begin production of the chip in 2009.

More at AP

Experts at a Scottish university say they have paved the way for the creation of tiny supercomputers which could fit in the palm of the hand. Engineers at the University of Edinburgh studied the behaviour of wires which were 1,000 times thinner than human hair. This major scientific breakthrough in nanotechnology, particularly understanding the behavior of microscopic wires, could pave the way for the development of much smaller microchips using thinner wires, a requisite for building a tiny supercomputer.

They then created a tool which could help develop tiny microchips. German and Italian experts also worked on the project. Their findings will be published in the journal Science. The Edinburgh researchers teamed up with colleagues from the Karlsruhe Institute of Technology in Germany and the University of Rome, Italy, to look at how tiny wires behave when they are manipulated.

With the help of computers, they found that wires on a nanoscale, measured in millionths of a millimetre, behave quite differently from bigger wires. Dr Michael Zaiser, of Edinburgh’s school of engineering and electronics, said: “What we found is when we made these wires smaller and smaller they started to behave in a very funny way.”

The discovery should help ensure that wiring in electronic devices remains effective, even in a supercomputer the size of a matchbox. “Holding a supercomputer in the palm of your hand will one day be possible - and we are going to make sure all the wires are in the right place.”

More at BBCNews

The world’s tiniest radio is a step closer to reality. US scientists have unveiled a detector thousands of times smaller than the diameter of a human hair that can translate radio waves into sound.

According to a University of California team, the study marks the first time that a nano-sized detector has been demonstrated in a working radio system. Made of carbon nanotubes a few atoms across, it is almost 1,000 times smaller than current radio technology. Peter Burke and Chris Rutherglen incorporated the microscopic detector into a complete radio system.

They used it to transmit classical music wirelessly from an iPod to a speaker several metres away from the music player. Full details of their findings will be published next month in the American Chemical Society’s Nano Letters.

“Though we have only demonstrated the critical component of the entire radio system out of a nanotube (the demodulator), it is conceivable in the future that all components could be nanoscale, thus allowing a truly nanoscale wireless communications system,” they write.

More at BBC News