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Electric Stress-Induced Threshold Voltage Instability of Multilayer MoS2 Field Effect Transistors

Electric Stress-Induced Threshold Voltage Instability of Multilayer MoS2 Field Effect Transistors | Research | Scoop.it

The gate bias stress effects of multilayered MoS2 field effect transistors (FETs) with a back-gated configuration is investigated. The electrical stability of the MoS2 FETs can be significantly influenced by the electrical stress type, relative sweep rate, and stress time in an ambient environment. Specifically, when a positive gate bias stress was applied to the MoS2 FET, the current of the device decreased and its threshold shifted in the positive gate bias direction. In contrast, with a negative gate bias stress, the current of the device increased and the threshold shifted in the negative gate bias direction. The gate bias stress effects were enhanced when a gate bias was applied for a longer time or when a slower sweep rate was used. These phenomena can be explained by the charge trapping due to the adsorption or desorption of oxygen and/or water on the MoS2 surface with a positive or negative gate bias, respectively, under an ambient environment. This study will be helpful in understanding the electrical-stress-induced instability of the MoS2-based electronic devices and will also give insight into the design of desirable devices for electronics applications.

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New simple setup for X-ray phase contrast

New simple setup for X-ray phase contrast | Research | Scoop.it

X-ray phase-contrast imaging is a method that uses the refraction of X-rays through a specimen instead of attenuation resulting from absorption. The images produced with this method are often of much higher quality than those based on absorption. The scientists in the team of Prof. Franz Pfeiffer are particularly interested in developing new approaches for biomedical X-ray imaging and therapy – including X-ray phase-contrast imaging. One main goal is to make this method available for clinical applications such as diagnosis of cancer or osteoporosis in the future.

In their new study, the scientists have now developed an extremely simple setup to produce X-ray phase-contrast images. The solution to many of their difficulties may seem counter-intuitive: Scramble the X-rays to give them a random structure. These speckles, as they are called in the field, encode a wealth of information on the sample as they travel through it. The scrambled X-rays are collected with a high-resolution X-ray camera, and the information is then extracted in a post-measurement analysis step.

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Work on 'singlet fission' can increase solar cell efficiency by as much as 30 percent

Work on 'singlet fission' can increase solar cell efficiency by as much as 30 percent | Research | Scoop.it

A perspective article published last month by University of California, Riverside chemists in the Journal of Physical Chemistry Letters was selected as an Editors Choice—an honor only a handful of research papers receive. The perspective reviews the chemists' work on "singlet fission," a process in which a single photon generates a pair of excited states. This 1->2 conversion process, as it is known, has the potential to boost solar cell efficiency by as much as 30 percent.

Applications of the research include more energy-efficient lighting and photodetectors with 200 percent efficiency that can be used for night vision. Biology may use singlet fission to deal with high-energy solar photons without generating excess heat, as a protective mechanism.

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Novel Materials Could Provide the Next Generation of Low-Power, Color Displays

Novel Materials Could Provide the Next Generation of Low-Power, Color Displays | Research | Scoop.it

Researchers at Oxford University have used a type of phase-change material to make devices whose color changes instantly in response to a small jolt of power.  The materials, which are used in some types of DVDs, could lead to ultra-low-power, full-color displays, according to an article describing the work in the journal Nature.

Displays made using the approach might overcome some of the drawbacks of other, low-energy display technologies, such as the E-ink used in Kindle e-readers. For example, pixels can switch on and off much faster than in the E-reader, which could make it useful for displaying video.

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Sand-based lithium ion batteries that outperform standard by three times

Sand-based lithium ion batteries that outperform standard by three times | Research | Scoop.it

Researchers at the University of California, Riverside's Bourns College of Engineering have created a lithium ion battery that outperforms the current industry standard by three times. The key material: sand. Yes, sand.

"This is the holy grail – a low cost, non-toxic, environmentally friendly way to produce high performance lithium ion battery anodes," said Zachary Favors, a graduate student working with Cengiz and Mihri Ozkan, both engineering professors at UC Riverside.

The idea came to Favors six months ago. He was relaxing on the beach after surfing in San Clemente, Calif. when he picked up some sand, took a close look at it and saw it was made up primarily of quartz, or silicon dioxide.

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The new atomic age: building smaller, greener electronics

The new atomic age: building smaller, greener electronics | Research | Scoop.it

The digital age has resulted in a succession of smaller, cleaner and less power-hungry technologies since the days the personal computer fit atop a desk, replacing mainframe models that once filled entire rooms. Desktop PCs have since given way to smaller and smaller laptops, smartphones and devices that most of us carry around in our pockets.

But as Wolkow points out, this technological shrinkage can only go so far when using traditional transistor-based integrated circuits. That’s why he and his research team are aiming to build entirely new technologies at the atomic scale.

“Our ultimate goal is to make ultra-low-power electronics because that’s what is most demanded by the world right now,” said Wolkow, the iCORE Chair in Nanoscale Information and Communications Technology in the Faculty of Science. “We are approaching some fundamental limits that will stop the 30-year-long drive to make things faster, cheaper, better and smaller; this will come to an end soon.

“An entirely new method of computing will be necessary.”

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More pores for more power

More pores for more power | Research | Scoop.it

Whether or not the future of automotive traffic belongs to the softly purring electric car depends largely on the development of its batteries. The industry is currently placing most of its hopes in lithium-sulfur batteries, which have a very high storage capacity. Moreover, thanks to the inclusion of sulfur atoms, they are cheaper to make and less toxic than conventional lithium-ion power packs.

However, the lithium-sulfur battery still presents several major challenges that need to be resolved until it can be integrated into cars. For example, both the rate and the number of possible charge-discharge cycles need to be increased before the lithium-sulfur battery can become a realistic alternative to lithium-ion batteries.

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Bionic particles self-assemble to capture light

Bionic particles self-assemble to capture light | Research | Scoop.it

Inspired by fictional cyborgs like Terminator, a team of researchers at the University of Michigan and the University of Pittsburgh has made the first bionic particles from semiconductors and proteins.

These particles recreate the heart of the process that allows plants to turn sunlight into fuel.

"Human endeavors to transform the energy of sunlight into biofuels using either artificial materials or whole organisms have low efficiency," said Nicholas Kotov, the Florence B. Cejka Professor of Engineering at the University of Michigan, who led the experiment.

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Scientists use nanoparticles to control growth of materials

Scientists use nanoparticles to control growth of materials | Research | Scoop.it

Growth is a ubiquitous phenomenon in plants and animals. But it also occurs naturally in chemicals, metals and other inorganic materials. That fact has, for decades, posed a major challenge for scientists and engineers, because controlling the growth within materials is critical for creating products with uniform physical properties so that they can be used as components of machinery and electronic devices. The challenge has been particularly vexing when the materials' molecular building blocks grow rapidly or are processed under harsh conditions such as high temperatures.

 Now, a team led by researchers from the UCLA Henry Samueli School of Engineering and Applied Science has developed a new process to control molecular growth within the "building block" components of inorganic materials. The method, which uses nanoparticles to organize the components during a critical phase of the manufacturing process, could lead to innovative new materials, such as self-lubricating bearings for engines, and it could make it feasible for them to be mass-produced.

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Dual carbon battery that charges 20 times faster than current lithium ion batteries

Dual carbon battery that charges 20 times faster than current lithium ion batteries | Research | Scoop.it

Japanese power company, Power Japan Plus has announced the development of a new type of battery intended for use in automobiles and other applications, the Ryden or dual carbon battery. The company claims the battery charges 20 times faster than current lithium ion batteries, doesn't heat up, so it doesn't require cooling and is cost competitive with other current batteries used in cars and trucks. They believe the battery will be a game-changer, leading to a surge in sales of hybrid and all electric vehicles.

Representatives for Power Japan say the battery is actually something completely new—it's made of carbon instead of nickel, cobalt or manganese. Not only does that make it cheaper to make but it does away with the thermal change that exists with current batteries that necessitate the installation of cooling systems (and does away with the associated fire hazard in crashes). They add that the carbon they use is new as well—it's an organic compound grown from cotton fibers. That means that when the battery is no longer useful, it can be easily recycled. Due to its structure, it's also able to be fully discharged without damage, which means more power can be used before recharging, slightly increasing distance capabilities. The new battery can also be configured to fit in a standard 18650 cell and the unique design also lends itself to higher than average reliability, with a lifespan of 3,000 charge/discharge cycles.

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Discovery of Rare Form of Iron Oxide in Ancient Chinese Pottery

Discovery of Rare Form of Iron Oxide in Ancient Chinese Pottery | Research | Scoop.it

New analysis of ancient Jian wares reveals the distinctive pottery contains an unexpected and highly unusual form of iron oxide. This rare compound, called epsilon-phase iron oxide, was only recently discovered and characterized by scientists and so far has been extremely difficult to create with modern techniques.

“What is amazing is that the ‘perfect synthesis conditions’ for epsilon-phase iron oxide were encountered 1000 years ago by Chinese potters,” says Catherine Dejoie, scientist at Berkley Lab’s Advanced Light Source and ETH Zurich. The study, published May 13 in Scientific Reports, could lead to an easier, more reliable synthesis of epsilon-phase iron oxide, enabling better, cheaper magnetic materials including those used for data storage.

The study was performed by an international team of researchers from China, France, Switzerland, and the United States, using a variety of analysis techniques at Berkeley Lab’s Advanced Light Source, the Stanford Synchrotron Radiation Lightsource at SLAC National Accelerator Laboratory, and the Centre d’Elaboration de Matériaux et d’Etudes Structruales in France. In addition to Dejoie, Berkeley Lab scientists Kai Chen, Martin Kunz, Nobumichi Tamura and Zhi Liu were also authors on the paper.

 

 

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Environmentally friendly solar cell pushes forward the 'next big thing in photovoltaics'

Environmentally friendly solar cell pushes forward the 'next big thing in photovoltaics' | Research | Scoop.it

Northwestern University researchers are the first to develop a new solar cell with good efficiency that uses tin instead of lead perovskite as the harvester of light. The low-cost, environmentally friendly solar cell can be made easily using "bench" chemistry—no fancy equipment or hazardous materials.

"This is a breakthrough in taking the lead out of a very promising type of solar cell, called a perovskite," said Mercouri G. Kanatzidis, an inorganic chemist with expertise in dealing with tin. "Tin is a very viable material, and we have shown the material does work as an efficient solar cell."

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Edgy Look at 2D Molybdenum Disulfide

Edgy Look at 2D Molybdenum Disulfide | Research | Scoop.it

The drive to develop ultrasmall and ultrafast electronic devices using a single atomic layer of semiconductors, such as transition metal dichalcogenides, has received a significant boost. Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have recorded the first observations of a strong nonlinear optical resonance along the edges of a single layer of molybdenum disulfide. The existence of these edge states is key to the use of molybdenum disulfide in nanoelectronics, as well as a catalyst for the hydrogen evolution reaction in fuel cells, desulfurization and other chemical reactions.

“We observed strong nonlinear optical resonances at the edges of a two-dimensional crystal of molybdenum disulfide” says Xiang Zhang, a faculty scientist with Berkeley Lab’s Materials Sciences Division who led this study. “These one-dimensional edge states are the result of electronic structure changes and may enable novel nanoelectronics and photonic devices. These edges have also long been suspected to be the active sites for the electrocatalytic hydrogen evolution reaction in energy applications. We also discovered extraordinary second harmonic light generation properties that may be used for the in situ monitoring of electronic changes and chemical reactions that occur at the one-dimensional atomic edges.”

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Nanoparticle based coating for aircraft engines may triple service life and reduce fuel consumption

Nanoparticle based coating for aircraft engines may triple service life and reduce fuel consumption | Research | Scoop.it

Researchers at University West in Sweden have started using nanoparticles in the heat-insulating surface layer that protects aircraft engines from heat. In tests, this increased the service life of the coating by 300%. This is something that interests the aircraft industry to a very great degree, and the hope is that motors with the new layers will be in production within two years. 

To increase the service life of aircraft engines, a heat-insulating surface layer is sprayed on top of the metal components. Thanks to this extra layer, the engine is shielded from heat. The temperature can also be raised, which leads to increased efficiency, reduced emissions, and decreased fuel consumption.

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Arrays of electrons could form the basis for future scalable quantum computers

Arrays of electrons could form the basis for future scalable quantum computers | Research | Scoop.it

A single electron trapped in a semiconductor nanostructure can form the most basic of building blocks for a quantum computer. Before practical quantum computers can be realized, however, scientists need to develop a scalable architecture that allows full control over individual electrons in computational arrays.

Matthieu Delbecq and colleagues from the RIKEN Center for Emergent Matter Science, in collaboration with researchers from Purdue University in the United States, have now demonstrated the scalability of quantum dot architectures by trapping and controlling four electrons in a single device1.

Electrons have a property known as spin that can be either 'up' or 'down'. This is the same binary coding as used in conventional computing, but electrons can also be linked at the quantum level to form quantum bits, or 'qubits', that can have many more usable states, providing dramatic improvements in computational performance.

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Rice's silicon oxide memories catch manufacturers' eye

Rice's silicon oxide memories catch manufacturers' eye | Research | Scoop.it

Rice University's breakthrough silicon oxide technology for high-density, next-generation computer memory is one step closer to mass production, thanks to a refinement that will allow manufacturers to fabricate devices at room temperature with conventional production methods.

First discovered five years ago, Rice's silicon oxide memories are a type of two-terminal, "resistive random-access memory" (RRAM) technology. In a new paper available online in the American Chemical Society journal Nano Letters, a Rice team led by chemist James Tour compared its RRAM technology to more than a dozen competing versions.

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IBM bets $3 billion on the death of silicon chips

IBM bets $3 billion on the death of silicon chips | Research | Scoop.it

IBM is worried that the age of silicon may be drawing to a close. So it's going to spend $3 billion (£1.75 billion) over the next half-decade to try and find new ways to power the future generations of microprocessors.

"We really do see the clock ticking on silicon," says Tom Rosamilia, Senior Vice President of IBM Systems & Technology Group.

Today's state-of-the-art IBM chips use silicon components that are already tiny -- just 22 nanometers in width. But looking about five years into the future, parts become so small that it becomes extremely difficult to maintain a reliable on or off state. "As we get into the 7 nanometer timeframe, things really begin to taper off," Rosamilia says.

So the first step of IBM's $3 billion (£1.75 billion) quest will fund research into ways of making these smaller chip components work -- even if they don't use silicon. IBM has high hopes for a silicon alternative, called carbon nanotubes, but the concept still needs work if it's going to become as easy to crank out carbon nanotube chips as their silicon alternatives. Another promising area is silicon nanophotonics: a way of using light instead of electrical signals to send data around the chip.

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Silicon sponge improves lithium-ion battery performance

Silicon sponge improves lithium-ion battery performance | Research | Scoop.it

The lithium-ion batteries that power our laptops and electric vehicles could store more energy and run longer on a single charge with the help of a sponge-like silicon material.

Researchers developed the porous material to replace the graphite traditionally used in one of the battery's electrodes, as silicon has more than 10 times the energy storage capacity of graphite. A paper describing the material's performance as a lithium-ion battery electrode was published today in Nature Communications.

"Silicon has long been sought as a way to improve the performance of lithium-ion batteries, but silicon swells so much when it is charged that it can break apart, making a silicon electrode inoperable," said Pacific Northwest National Laboratory Fellow Ji-Guang "Jason" Zhang. "The porous, sponge-like material we've developed gives silicon the room it needs to expand without breaking."

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Harvesting energy from devices

Harvesting energy from devices | Research | Scoop.it

If there's one thing nearly all modern technology has in common, it's heat. Whether it's your car, computer, television, or even refrigerator, they all generate large amounts of heat. And nearly all of it goes to waste.

In an effort to recapture some of that energy and transform it into electricity, a team of researchers has developed computer simulations for a new type of meta-material that would have the ability to control heat and electrical current independently. Their work is described in a recently published paper in Physical Review X.

The team included Yuki Sato, a fellow at the Rowland Institute at Harvard, and Salvatore Savo, a postdoctoral fellow at the institute, along with Massimo Moccia, Giuseppe Castaldi, and Vincenzo Galdi at the University of Sannio in Italy.

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The Greek Mythical Hero of Storage Class Memory

The Greek Mythical Hero of Storage Class Memory | Research | Scoop.it

Theseus was a great hero in Greek mythology known for qualities such as strength, courage and wisdom. Therefore it’s no surprise that a team of Greek IBM scientists in Zurich and a professor from the University of Patras, Greece, borrowed his name as a codeword for a groundbreaking new memory technology, which combines flash with phase change memory (PCM) on a PCI-e card. Initial tests have clocked 12x and 275x improvements — and that’s no myth.

While flash is ubiquitous in everything from USB sticks to data centers, PCM is still relatively unknown.

First proposed for memory in the 1970s, phase-change materials, the premise of the technology, exhibit two metastable states which can store data when placed between two electrically conducting electrodes. When a high or medium current is applied to the material, it can be programmed to write a ‘0’ in the amorphous phase or a ‘1’ in the crystalline phase. A low current is then applied to read out the cells to access the data. Blue ray discs are an example of a phase change material.

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Improved supercapacitors for super batteries, electric vehicles

Improved supercapacitors for super batteries, electric vehicles | Research | Scoop.it

Researchers at the University of California, Riverside have developed a novel nanometer scale ruthenium oxide anchored nanocarbon graphene foam architecture that improves the performance of supercapacitors, a development that could mean faster acceleration in electric vehicles and longer battery life in portable electronics.

The researchers found that supercapacitors, an energy storage device like batteries and fuel cells, based on transition metal oxide modified nanocarbon graphene foam electrode could work safely in aqueous electrolyte and deliver two times more energyand power compared to supercapacitors commercially available today.

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New lithium battery

New lithium battery | Research | Scoop.it

The long life of lithium ion batteries makes them the rechargeable of choice for everything from implantable medical devices to wearable consumer electronics. But lithium ion batteries rely on liquid chemistries involving lithium salts dissolved in organic solvents, creating flame risks that would be avoided if the cells were completely solid-state.

Now a team of researchers at Tohoku University in Japan has created a new type of lithium ion conductor for future batteries that could be the basis for a whole new generation of solid-state batteries. It uses rock salt Lithium Borohydride (LiBH4), a well-known agent in organic chemistry laboratories that has been considered for batteries before, but up to now has only worked at high temperatures or pressures.

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Nanotubes and Graphene Foam Make Hybrid Energy Storage Device

Nanotubes and Graphene Foam Make Hybrid Energy Storage Device | Research | Scoop.it

A paper in the journal Science earlier this year suggested that the problem of nomenclature for energy storage devices—specifically, defining the difference between what is a supercapacitor and what is a pseudocapacitor—is beginning to hold back development in the field.

To confuse matters further, researchers out of University of California Riverside have now developed an energy storage device that they define as a hybrid between a supercapacitor and a pseudocapacitor, but they prefer to term simply a supercapacitor.

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Bottom-Up Manufacturing of Nanowires on Silicon Expands Its Capabilities

Bottom-Up Manufacturing of Nanowires on Silicon Expands Its Capabilities | Research | Scoop.it
Researchers develop a way to grow nanowires on silicon that is adaptable to today's manufacturing processes
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Atomic mechanism for historic materials transformation

Atomic mechanism for historic materials transformation | Research | Scoop.it

SLAC-led researchers have made the first direct measurements of a small and extremely rapid atomic rearrangement, associated with a class called martensitic transformations, that dramatically changes the properties of many important materials, such as doubling the hardness of steel and causing shape-memory alloys to revert to a previous shape.

Using high-pressure shock waves and ultrashort X-ray pulses at the Linac Coherent Light Source (LCLS), the researchers observed the details of how this transformation changed the internal atomic structure of a model system, perfect nanocrystals of cadmium sulfide. In the process, they saw for the first time that the nanocrystals pass through a theoretically-predicted intermediate state when undergoing this change.

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Semiconductor Manipulates IR Light

Semiconductor Manipulates IR Light | Research | Scoop.it

Developed by a team from the University of California, Santa Barbara, the technology uses erbium, a rare-earth metal that has the ability to absorb light in the visible as well as infrared wavelengths. 
Pairing it with antimony (Sb), the researchers embedded the resulting compound — erbium antimonide (ErSb) — as semimetallic nanostructures within the semiconducting matrix of gallium antimonide (GaSb). “The nanostructures are coherently embedded, without introducing noticeable defects, through the growth process by molecular beam epitaxy,” said Dr. Hong Lu, a researcher in UCSB’s materials and electrical and computer engineering departments, and a lead author of the study. “Secondly, we can control the size, the shape and the orientation of the nanostructures.” 

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