David Kirkpatrick

August 18, 2010

Ratcheting up data storage density

Via KurzweilAI.net —  ratcheting data density up a lot!

World record data density for ferroelectric recordin

August 18, 2010 by Editor

Scientists at Tohoku University in Japan have recorded data at a density of 4 trillion bits per square inch,  a world record for the experimental ferroelectric data storage method, and about eight times the density of today’s most advanced magnetic hard-disk drives.

The data-recording device uses a tiny cantilever tip that rides in contact with the surface of a ferroelectric material. To write data, an electric pulse is sent through the tip, changing the electric polarization and nonlinear dielectric constant of a tiny circular spot in the substrate beneath. To read data, the same tip detects the variations in nonlinear dielectric constant in the altered regions.

“We expect this ferroelectric data storage system to be a candidate to succeed magnetic hard disk drives or flash memory, at least in applications for which extremely high data density and small physical volume is required,” said Tohoku University scientist Dr. Yasuo Cho.

Existing data storage technologies also continue to improve. Disk drive maker Seagate, for example, has said it can envision achieving a density of 50 trillion bits per square inch.

“Actual Information Storage with a Recording Density of 4 Tbit/inch^2 in a ferroelectric recording medium” by Kenkou Tanaka and Yasuo Cho will appear in the journal Applied Physics Letters.

More info: American Institute of Physics news

August 11, 2010

Improving displays

And display improvements are increasingly important given the rapid evolution in types of consumer electronics — e-readers, smartphones, more complex touch screens, tablet/pad computers, et.al. — and the different types of high-performance displays needed to maximize these technologies.

The release:

Better displays ahead

IMAGE: This is a prototype of the vertical stack multi-color electrowetting display device is shown in the photograph. Arrays of ~1,000-2,000 pixels were constructed with pixel sizes of 200 × 600…

Click here for more information.

This release is also available in Chinese.College Park, MD (August 10, 2010) — Sleek design and ease of use are just two of the main reasons consumers are increasingly attracted to tablets and e-readers. And these devices are only going to get better — display technology improvements are on the way.

Several e-reader products on the market today use electrophoretic displays, in which each pixel consists of microscopic capsules that contain black and white particles moving in opposite directions under the influence of an electric field. A serious drawback to this technology is that the screen image is closer to black-on-gray than black-on-white. Also, the slow switching speed (~1 second) due to the limited velocity of the particles prevents integration of other highly desirable features such as touch commands, animation, and video.

Researchers at the University of Cincinnati Nanoelectronics Laboratory are actively pursuing an alternative approach for low-power displays. Their assessment of the future of display technologies appears in the American Institute of Physics’ Applied Physics Letters.

“Our approach is based on the concept of vertically stacking electrowetting devices,” explains professor Andrew J. Steckl, director of the NanoLab at UC’s Department of Electrical and Computer Engineering. “The electric field controls the ‘wetting’ properties on a fluoropolymer surface, which results in rapid manipulation of liquid on a micrometer scale. Electrowetting displays can operate in both reflective and transmissive modes, broadening their range of display applications. And now, improvements of the hydrophobic insulator material and the working liquids enable EW operation at fairly low driving voltages (~15V).”

Steckl and Dr. Han You, a research associate in the NanoLab, have demonstrated that the vertical stack electrowetting structure can produce multi-color e-paper devices, with the potential for higher resolution than the conventional side-by-side pixel approach. Furthermore, their device has switching speeds that enable video content displays.

What does all of this mean for the consumer? Essentially, tablets and e-readers are about to become capable of even more and look even better doing it. Compared to other technologies, electrowetting reflective display screens boast many advantages. The electrowetting displays are very thin, have a switching speed capable of video display, a wide viewing angle and, just as important, Steckl says, they aren’t power hogs.

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The article, “Three-Color Electrowetting Display Device for Electronic Paper” by Han You and Andrew J. Steckl will appear in the journal Applied Physics Lettershttp://apl.aip.org/applab/v97/i2/p023514_s1

Image Caption: A prototype of the vertical stack multi-color electrowetting display device is shown in the photograph. Arrays of ~1,000-2,000 pixels were constructed with pixel sizes of 200 × 600 and 300 × 900 µm.

ABOUT APPLIED PHYSICS LETTERS

Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, Applied Physics Letters offers prompt publication of new experimental and theoretical papers bearing on applications of physics phenomena to all branches of science, engineering, and modern technology. Content is published online daily, collected into weekly online and printed issues (52 issues per year). See: http://apl.aip.org/

ABOUT AIP

The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world’s largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.

August 5, 2010

Selenium improves solar efficiency

I like the “anti-sunscreen” intro to this news on improving the efficiency of photovoltaic solar cells with selenium.

The release:

Selenium makes more efficient solar cells

This release is also available in Chinese.

IMAGE: This is a sunset over the Pacific Ocean as seen from Highway 1 south of Monterey, Calif. LBNL’s Marie Mayer, who took the photo, calls sunlight and water “two sustainable…

Click here for more information.

College Park, MD (August 3, 2010) — Call it the anti-sunscreen. That’s more or less the description of what many solar energy researchers would like to find — light-catching substances that could be added to photovoltaic materials in order to convert more of the sun’s energy into carbon-free electricity.

Research reported in the journal Applied Physics Letters, published by the American Institute of Physics (AIP), describes how solar power could potentially be harvested by using oxide materials that contain the element selenium. A team at the Lawrence Berkeley National Laboratory in Berkeley, California, embedded selenium in zinc oxide, a relatively inexpensive material that could be promising for solar power conversion if it could make more efficient use of the sun’s energy. The team found that even a relatively small amount of selenium, just 9 percent of the mostly zinc-oxide base, dramatically boosted the material’s efficiency in absorbing light.

“Researchers are exploring ways to make solar cells both less expensive and more efficient; this result potentially addresses both of those needs,” says author Marie Mayer, a fourth-year University of California, Berkeley doctoral student based out of LBNL’s Solar Materials Energy Research Group, which is working on novel materials for sustainable clean-energy sources.

Mayer says that photoelectrochemical water splitting, using energy from the sun to cleave water into hydrogen and oxygen gases, could potentially be the most exciting future application for her work. Harnessing this reaction is key to the eventual production of zero-emission hydrogen powered vehicles, which hypothetically will run only on water and sunlight. Like most researchers, Mayer isn’t predicting hydrogen cars on the roads in any meaningful numbers soon. Still, the great thing about solar power, she says, is that “if you can dream it, someone is trying to research it.”

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The article, “Band structure engineering of ZnO1-xSex alloys” by Marie A. Mayer, Derrick T. Speaks, Kin Man Yu, Samuel S. Mao, Eugene E. Haller, and Wladek Walukiewicz will appear in the journal Applied Physics Letters. See: http://apl.aip.org/applab/v97/i2/p022104_s1

ABOUT APPLIED PHYSICS LETTERS

Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, Applied Physics Letters offers prompt publication of new experimental and theoretical papers bearing on applications of physics phenomena to all branches of science, engineering, and modern technology. Content is published online daily, collected into weekly online and printed issues (52 issues per year). See: http://apl.aip.org/

ABOUT AIP

The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world’s largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.

August 4, 2010

Lower cost solar cells

Yesterday I blogged about a new solar energy process that might supplant photovoltaics, at least in large-scale desert installations because of dramatically increased efficiency. Today it’s a breakthrough with photovoltaic solar cells in regards to production cost. I like seeing all this innovation is the solar space, especially since it’s a bit all over the map. Incremental improvement is always nice, but anytime research is going after all sorts of targets the odds of a major breakthrough go up.

From the second link:

One of the most promising technologies for making inexpensive but reasonably efficient solar photovoltaic cells just got much cheaper. Scientists at the University of Toronto in Canada have shown that inexpensive nickel can work just as well as gold for one of the critical electrical contacts that gather the electrical current produced by their colloidal quantum dot solar cells.

The change to nickel can reduce the cell’s already low material costs by 40 to 80 percent, says Lukasz Brzozowski, the director of the Photovoltaics Research Program in Professor Ted Sargent’s group. They present their research in the July 12, 2010 issue of Applied Physics Letters.

May 12, 2010

Graphene transistor

Filed under: Science, Technology — Tags: , , , , , — David Kirkpatrick @ 12:23 am

One step toward nanoelectronics.

From the link:

For years, scientists and researchers have been looking into the properties of carbon nanotubes and graphene for use in nanoelectronics. “There is no real mass application of devices based on graphene and carbon nanotubes,” Zhenxing Wang tells PhysOrg.com. “This is really an opportunity for them to show their capabilities.”

Wang is part of a group at the Key Laboratory for the Physics and Chemistry of  at Peking University in Beijing. Along with Zhiyong Zhang, Huilong Xu, Li Ding, Sheng Wang, and Lian-Mao Peng, Wang tested a top-gate  field-effect transistor based frequency doubler in order to gauge its performance. They were able to show that a graphene based frequency doubler can provide more than 90% converting efficiency, while the corresponding value is not larger than 30% for conventional frequency doubler. Their work is published in : “A high-performance top-gate graphene field-effect transistor based frequency doubler.”

April 22, 2010

Nanotech improving computer memory

Through magnetic nanodots. As the article covers, this advancement is in RAM.

From the link:

Using magnetic nanodots in the vortex state, researchers have designed a new kind of non-volatile memory that could offer increased speed and density for next-generation non-volatile random access memories (RAM). The new design takes advantage of magnetic vortices’ ability to store binary information as positive or negative core polarities, which can be controlled by simply changing the frequency of the rotating vortex cores of the nanodots.

The new technique, called frequency-controlled magnetic vortex memory, was developed by a team of researchers, B. Pigeau, et al., from France, Germany, and the US. Their study is published in a recent issue of .

As the researchers explain, the concept of using magnetic nano-objects to store binary information for magnetic RAM has previously been investigated, but it’s been difficult to find a mechanism to reverse the magnetization inside individual nano-objects. Here, the researchers achieve this reversal by using microwave pulses in combination with a static magnetic field. In this scheme, large and small rotating core frequencies are associated with positive and negative core polarities, respectively. In a positive core polarity, the core is parallel to the applied magnetic field, while in a negative core polarity, the core is antiparallel to the applied magnetic field. An extremely sensitive magnetic resonance force microscope (MRFM) is used to address the  of magnetic nanodots’ vortex core rotations, allowing the researchers to control the polarity states of individual nanodots.

December 12, 2009

“Hot electrons” and solar cells

Filed under: Science — Tags: , , , , — David Kirkpatrick @ 4:29 pm

The latest solar breakthrough news.

The release:

Elusive ‘hot’ electrons captured in ultra-thin solar cells

Shrinking cells snares charges in less than one-trillionth of a second

CHESTNUT HILL, MA (12/11/2009) – Boston College researchers have observed the “hot electron” effect in a solar cell for the first time and successfully harvested the elusive charges using ultra-thin solar cells, opening a potential avenue to improved solar power efficiency, the authors report in the current online edition of Applied Physics Letters.

When light is captured in solar cells, it generates free electrons in a range of energy states. But in order to snare these charges, the electrons must reach the bottom of the conduction band. The problem has been that these highly energized “hot” electrons lose much of their energy to heat along the way.

Hot electrons have been observed in other devices, such as semiconductors. But their high kinetic energy can cause these electrons, also known as “hot carriers,” to degrade a device. Researchers have long theorized about the benefits of harnessing hot electrons for solar power through so-called “3rd generation” devices.

By using ultrathin solar cells – a film fewer than 30 nanometers thick – the team developed a mechanism able to extract hot electrons in the moments before they cool – effectively opening a new “escape hatch” through which they typically don’t travel, said co-author Michael J. Naughton, the Evelyn J. and Robert A. Ferris Professor of Physics at Boston College.

The team’s success centered on minimizing the environment within which the electrons are able to escape, said Professor of Physics Krzysztof Kempa, lead author of the paper.

Kempa compared the challenge to trying to heat a swimming pool with a pot of boiling water. Drop the pot into the center of the pool and there would be no change in temperature at the edge because the heat would dissipate en route. But drop the pot into a sink filled with cold water and the heat would likely raise the temperature in the smaller area.

“We have shrunk the size of the solar cell by making it thin,” Kempa said. “In doing so, we are bringing these hot electrons closer to the surface, so they can be collected more readily. These electrons have to be captured in less than a picosecond, which is less than one trillionth of a second.”

The ultrathin cells demonstrated overall power conversion efficiency of approximately 3 percent using absorbers one fiftieth as thick as conventional cells. The team attributed the gains to the capture of hot electrons and an accompanying reduction in voltage-sapping heat. The researchers acknowledged the film’s efficiency is limited by the negligible light collection of ultra-thin junctions. However, combining the film with better light-trapping technology – such as nanowire structures – could significantly increase efficiency in an ultra-thin hot electron solar cell technology.

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In addition to Naughton and Kempa, the research team included Professor of Physics Zhifeng Ren, Research Associate Professor and Laboratory Director Andrzej A. Herczynski, Research Scientist Yantao Gao, doctoral student Timothy Kirkpatrick, and Jakub Rybczynski of Solasta Corp., of Newton MA, which supported the research. Naughton, Kempa and Ren are principals in the clean energy firm as well.

November 21, 2009

Carbon nanotube supercapacitors

Flawed carbon nanotubes may lead to supercapacitors.

From the link:

Most people would like to be able to charge their cell phones and other personal electronics quickly and not too often. A recent discovery made by UC San Diego engineers could lead to carbon nanotube-based supercapacitors that could do just this.

In recent research, published in , Prabhakar Bandaru, a professor in the UCSD Department of Mechanical and Aerospace Engineering, along with graduate student Mark Hoefer, have found that artificially introduced defects in nanotubes can aid the development of supercapacitors.

“While batteries have large , they take a long time to charge; while electrostatic capacitors can charge quickly but typically have limited capacity. However, supercapacitors/electrochemical capacitors incorporate the advantages of both,” Bandaru said.

Of course I mostly ran this post just to add to the excuse for running this awesome image of a carbon nanotube. Earlier this week I featured an incredible image of graphene. We’re getting some just simply amazing looks into the atomic world right now. And it’ll only get better.

Carbon nanotubes could serve as supercapacitor electrodes with enhanced charge and energy storage capacity (inset: a magnified view of a single carbon nanotube).

Credit: UC San Diego

June 2, 2009

Making water run uphill …

… through lasers and nanostructures. Lots of possible apps here, plus it’s just freaking cool.

The release:

Scientists create metal that pumps liquid uphill

Ultra-fast laser makes metal that attracts, repels and guides liquids

IMAGE: Chunlei Guo uses the femtosecond laser (behind him) to create nanostructures in metal that can move liquid uphill.

Click here for more information. 

In nature, trees pull vast amounts of water from their roots up to their leaves hundreds of feet above the ground through capillary action, but now scientists at the University of Rochester have created a simple slab of metal that lifts liquid using the same principle—but does so at a speed that would make nature envious.

The metal, revealed in an upcoming issue of Applied Physics Letters, may prove invaluable in pumping microscopic amounts of liquid around a medical diagnostic chip, cooling a computer’s processor, or turning almost any simple metal into an anti-bacterial surface.

“We’re able to change the surface structure of almost any piece of metal so that we can control how liquid responds to it,” says Chunlei Guo, associate professor of optics at the University of Rochester. “We can even control the direction in which the liquid flows, or whether liquid flows at all.”

Guo and his assistant, Anatoliy Vorobyev, use an ultra-fast burst of laser light to change the surface of a metal, forming nanoscale and microscale pits, globules, and strands across the metal’s surface. The laser, called a femtosecond laser, produces pulses lasting only a few quadrillionths of a second—a femtosecond is to a second what a second is to about 32 million years. During its brief burst, Guo’s laser unleashes as much power as the entire electric grid of North America does, all focused onto a spot the size of a needlepoint, he says.

The wicking process, which on Guo’s metal moves at a quick one centimeter per second speed against gravity, is very similar to the phenomenon that pulls spilled milk into a paper towel or creates “tears of wine” in a wineglass—molecular attractions and evaporation combine to move a liquid against gravity, says Guo. Likewise, Guo’s nanostructures change the way molecules of a liquid interact with the molecules of the metal, allowing them to become more or less attracted to each other, depending on Guo’s settings. At a certain size, the metal nanostructures adhere more readily to the liquid’s molecules than the liquid’s molecules adhere to each other, causing the liquid to quickly spread out across the metal. Combined with the effects of evaporation as the liquid spreads, this molecular interaction creates the fast wicking effect in Guo’s metals.

Adding laser-etched channels into the metal further enhances Guo’s control of the liquid.

“Imagine a huge waterway system shrunk down onto a tiny chip, like the electronic circuit printed on a microprocessor, so we can perform chemical or biological work with a tiny bit of liquid,” says Guo. “Blood could precisely travel along a certain path to a sensor for disease diagnostics. With such a tiny system, a nurse wouldn’t need to draw a whole tube of blood for a test. A scratch on the skin might contain more than enough cells for a micro-analysis.”

Guo’s team has also created metal that reduces the attraction between water molecules and metal molecules, a phenomenon called hydrophobia. Since germs mostly consist of water, it’s all but impossible for them to grow on a hydrophobic surface, says Guo.

Currently, to alter an area of metal the size of a quarter takes 30 minutes or more, but Guo and Vorobyev are working on refining the technique to make it faster. Fortunately, despite the incredible intensity involved, the femtosecond laser can be powered by a simple wall outlet, meaning that when the process is refined, implementing it should be relatively simple.

Guo is also announcing this month in Physical Review Letters a femtosecond laser processing technique that can create incandescent light bulbs that use half as much energy, yet produce the same amount of light. In 2006, Guo’s team used the femtosecond laser to create metal with nanostructures that reflected almost no light at all, and in 2008 the team was able to tune the creation of nanostructures to reflect certain wavelengths of light—in effect turning almost any metal into almost any color.

 

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This research funded by the U.S. Air Force Office of Scientific Research and the National Science Foundation.

January 21, 2009

Latest on graphene — various substrate growth

Graphene is one of nanotech’s serious breakthroughs and here’s the latest on the single-atom thick carbon material.

The release:

Light-Speed Nanotech: Controlling the Nature of Graphene

Researchers at Rensselaer have developed a new method for controlling the conductive nature of graphene. Pictured is a rendering of two sheets of graphene, each with the thickness of just a single carbon atom, resting on top of a silicon dioxide substrate.

Researchers “tune” graphene’s properties by growing it on different surfaces

Researchers at Rensselaer Polytechnic Institute have discovered a new method for controlling the nature of graphene, bringing academia and industry potentially one step closer to realizing the mass production of graphene-based nanoelectronics.

Graphene, a one-atom-thick sheet of carbon, was discovered in 2004 and is considered a potential heir to copper and silicon as the fundamental building blocks of nanoelectronics. 

With help from an underlying substrate, researchers for the first time have demonstrated the ability to control the nature of graphene. Saroj Nayak, an associate professor in Rensselaer’s Department of Physics, Applied Physics, and Astronomy, along with Philip Shemella, a postdoctoral research associate in the same department, have determined that the chemistry of the surface on which graphene is deposited plays a key role in shaping the material’s conductive properties. The results are based on large-scale quantum mechanical simulations.

Results show that when deposited on a surface treated with oxygen, graphene exhibits semiconductor properties. When deposited on a material treated with hydrogen, however, graphene exhibits metallic properties.

“Depending on the chemistry of the surface, we can control the nature of the graphene to be metallic or semiconductor,” Nayak said. “Essentially, we are ‘tuning’ the electrical properties of material to suit our needs.” 

Conventionally, whenever a batch of graphene nanostructures is produced, some of the graphene is metallic, while the rest is semiconductor. It would be nearly impossible to separate the two on a large scale, Nayak said, yet realizing new graphene devices would require that they be comprised solely of metallic or semiconductor graphene. The new method for “tuning” the nature of graphene is a key step to making this possible, he said. 

Graphene’s excellent conductive properties make it attractive to researchers. Even at room temperature, electrons pass effortlessly, near the speed of light and with little resistance. This means a graphene interconnect would likely stay much cooler than a copper interconnect of the same size. Cooler is better, as heat produced by interconnects can have negative effects on both a computer chip’s speed and performance.

Results of the study were published this week in the paper “Electronic structure and band-gap modulation of graphene via substrate surface chemistry” in Applied Physics Letters, and are featured on the cover of the journal’s January 19 issue. 

Large-scale quantum simulations for the study were run on Rensselaer’s supercomputing system, the Computational Center for Nanotechnology Innovations (CCNI). 

Researchers received funding for the project from the New York State Interconnect Focus Center at Rensselaer.

Published January 20, 2009

October 3, 2008

Nanotech and better LCD displays

From the lededisplays could become brighter, lighter, and thinner.

And from the second link:

Scientists Zhibing Ge and Shin-Tson Wu from the University of Central Florida in Orlando have presented their improved LCD design in a recent issue of Applied Physics Letters. They used a nanowire grid polarizer (NWGP) for backlight recycling, which enhances the LCD’s optical efficiency and thereby reduces its power consumption.

“The method for fabricating large area wire-grid polarizers is advancing rapidly, benefiting from the huge research momentum of nano-imprinting technology,” Wu told PhysOrg.com. “Nowadays, it is possible to fabricate NWGPs with a pitch of 100 nanometers or smaller. Different from the reflective polarizers made from multilayer films, WGP is a grating structure which can exhibit a very high transmission contrast ratio. As a result, it holds potential for replacing the bottom sheet LP which is close to the backlight side in a LCD.”

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