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Posts Tagged ‘carbon nanotubes’

GlobalFoundries CTO Calls for Innovation in Chip Materials

Thursday, September 24th, 2015
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GlobalFoundries CTO Gary Patton

By Jeff Dorsch, Contributing Editor

“It’s really all about materials innovation,” said Gary Patton, chief technology officer of GlobalFoundries and head of the company’s worldwide research and development, in his keynote address on Tuesday at SEMI’s Strategic Materials Conference in Mountain View, Calif.

The semiconductor technology landscape looks challenging and even daunting at the moment. “We always figure out how to keep going,” Patton told the overflow audience.

The industry has reached “the end of the planar device era,” he added, and entered into “the 3D era,” with 3D chips and 3D stacking of chips in packaging.

Ahead in the not-too-distant future lies “the atomic era” of carbon nanotubes and other materials to replace silicon, Patton said, a theme that was reinforced over the conference’s two days, surrounded by information technology artifacts in the Computer History Museum.

Extreme-ultraviolet lithography is “a key challenging technology,” Patton observed. “We need to make it happen. EUV will take us into the 2020s.”

Double-patterning with immersion lithography will usher the industry into the 10-nanometer process node, according to the GlobalFoundries technologist. Implementing EUV will simplify a number of aspects of lithography, such as the multiple photomasks involved. “EUV will take us back to the 45-nanometer era,” Patton said.

He reviewed several areas of semiconductor manufacturing that will be changing in the near future, from the front end to the back end.

It was nearly three months ago that GlobalFoundries completed its acquisition of IBM Microelectronics. Patton served as vice president of IBM’s Semiconductor Research and Development Center for eight years prior to joining GlobalFoundries in July.

In his keynote, he touted the network of New York’s “Tech Valley,” taking in GlobalFoundries’ facilities in Malta, N.Y.; the Albany NanoTech Complex; and the former IBM chip facilities in East Fishkill, N.Y., and Burlington, Vt. “What we develop in Albany, we run in Malta,” Patton said.

GlobalFoundries, with its academic and industry partners, has 23 joint development projects in Albany, Patton noted, and is open to even more.

In an interview on Wednesday, Patton emphasized the development of “differentiated technologies” with the integration of IBM’s chip manufacturing operations. In addition to supplying processors for IBM’s server business over the next decade, GlobalFoundries also has IBM’s radio-frequency chip business, silicon germanium-based devices, power amplifiers, RF silicon-on-insulator technology, ASICs, and chips for wired communications, Patton noted.

The foundry is “ramping 14-nanometer technology” and working with Samsung Electronics on FinFET processes, Patton said. While the 14nm FinFET process covers advanced semiconductors, GlobalFoundries can also make lower-power parts with its 22nm fully-depleted SOI process, using the 22FDX platform.

GlobalFoundries was able to maintain the Trusted Foundry relationship with the U.S. Department of Defense with the IBM Microelectronics acquisition, according to Patton, and one business unit is devoted to aerospace and defense customers.

Asked about the delayed Fab 8.2 expansion in Malta, Patton said resumption of the project would depend on business conditions in the industry. “We’ll invest at a better time,” he said.

And what about the report concerning a Chinese financial entity approaching GlobalFoundries about a possible acquisition? “I have no knowledge of that,” Patton said.

Research Alert: January 26, 2015

Monday, January 26th, 2015

Solving an organic semiconductor mystery

Organic semiconductors are prized for light emitting diodes (LEDs), field effect transistors (FETs) and photovoltaic cells. As they can be printed from solution, they provide a highly scalable, cost-effective alternative to silicon-based devices. Uneven performances, however, have been a persistent problem. Scientists have known that the performance issues originate in the domain interfaces within organic semiconductor thin films, but have not known the cause. This mystery now appears to have been solved.

Naomi Ginsberg, a faculty chemist with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory and the University of California (UC) Berkeley, led a team that used a unique form of microscopy to study the domain interfaces within an especially high-performing solution-processed organic semiconductor called TIPS-pentacene. She and her team discovered a cluttered jumble of randomly oriented nanocrystallites that become kinetically trapped in the interfaces during solution casting. Like debris on a highway, these nanocrystallites impede the flow of charge-carriers.

“If the interfaces were neat and clean, they wouldn’t have such a large impact on performance, but the presence of the nanocrystallites reduces charge-carrier mobility,” Ginsberg says. “Our nanocrystallite model for the interface, which is consistent with observations, provides critical information that can be used to correlate solution-processing methods to optimal device performances.”

Ginsberg, who holds appointments with Berkeley Lab’s Physical Biosciences Division and its Materials Sciences Division, as well as UC Berkeley’s departments of chemistry and physics, is the corresponding author of a paper describing this research in Nature Communications. The paper is titled “Exciton dynamics reveals aggregates with intermolecular order at hidden interfaces in solution-cast organic semiconducting films.” Co-authors are Cathy Wong, Benjamin Cotts and Hao Wu.

Ginsberg and her group overcame the challenges by using transient absorption (TA) microscopy, a technique in which femtosecond laser pulses excite transient energy states and detectors measure the changes in the absorption spectra. The Berkeley researchers carried out TA microscopy on an optical microscope they constructed themselves that enabled them to generate focal volumes that are a thousand times smaller than is typical for conventional TA microscopes. They also deployed multiple different light polarizations that allowed them to isolate interface signals not seen in either of the adjacent domains.

“Instrumentation, including very good detectors, the painstaking collection of data to ensure good signal-to-noise ratios, and the way we crafted the experiment and analysis were all critical to our success,” Ginsberg says. “Our spatial resolution and light polarization sensitivity were also essential to be able to unequivocally see a signature of the interface that was not swamped by the bulk, which contributes much more to the raw signal by volume.”

The methology developed by Ginsberg and her team to uncover structural motifs at hidden interfaces in organic semiconductor thin films should add a predictive factor to scalable and affordable solution-processing of these materials. This predictive capability should help minimize discontinuities and maximize charge-carrier mobility. Currently, researchers use what is essentially a trial-and-error approach, in which different solution casting conditions are tested to see how well the resulting devices perform.

“Our methodology provides an important intermediary in the feedback loop of device optimization by characterizing the microscopic details of the films that go into the devices, and by inferring how the solution casting could have created the structures at the interfaces,” Ginsberg says. “As a result, we can suggest how to alter the delicate balance of solution casting parameters to make more functional films.”

Rice-sized laser, powered one electron at a time, bodes well for quantum computing

Princeton University researchers have built a rice grain-sized laser powered by single electrons tunneling through artificial atoms known as quantum dots. The tiny microwave laser, or “maser,” is a demonstration of the fundamental interactions between light and moving electrons.

The researchers built the device — which uses about one-billionth the electric current needed to power a hair dryer — while exploring how to use quantum dots, which are bits of semiconductor material that act like single atoms, as components for quantum computers.

“It is basically as small as you can go with these single-electron devices,” said Jason Petta, an associate professor of physics at Princeton who led the study, which was published in the journal Science.

The device demonstrates a major step forward for efforts to build quantum-computing systems out of semiconductor materials, according to co-author and collaborator Jacob Taylor, an adjunct assistant professor at the Joint Quantum Institute, University of Maryland-National Institute of Standards and Technology.

“I consider this to be a really important result for our long-term goal, which is entanglement between quantum bits in semiconductor-based devices,” Taylor said.

The original aim of the project was not to build a maser, but to explore how to use double quantum dots — which are two quantum dots joined together — as quantum bits, or qubits, the basic units of information in quantum computers.

“The goal was to get the double quantum dots to communicate with each other,” said Yinyu Liu, a physics graduate student in Petta’s lab. The team also included graduate student Jiri Stehlik and associate research scholar Christopher Eichler in Princeton’s Department of Physics, as well as postdoctoral researcher Michael Gullans of the Joint Quantum Institute.

Because quantum dots can communicate through the entanglement of light particles, or photons, the researchers designed dots that emit photons when single electrons leap from a higher energy level to a lower energy level to cross the double dot.

Each double quantum dot can only transfer one electron at a time, Petta explained. “It is like a line of people crossing a wide stream by leaping onto a rock so small that it can only hold one person,” he said. “They are forced to cross the stream one at a time. These double quantum dots are zero-dimensional as far as the electrons are concerned — they are trapped in all three spatial dimensions.”

The researchers fabricated the double quantum dots from extremely thin nanowires (about 50 nanometers, or a billionth of a meter, in diameter) made of a semiconductor material called indium arsenide. They patterned the indium arsenide wires over other even smaller metal wires that act as gate electrodes, which control the energy levels in the dots.

To construct the maser, they placed the two double dots about 6 millimeters apart in a cavity made of a superconducting material, niobium, which requires a temperature near absolute zero, around minus 459 degrees Fahrenheit. “This is the first time that the team at Princeton has demonstrated that there is a connection between two double quantum dots separated by nearly a centimeter, a substantial distance,” Taylor said.

When the device was switched on, electrons flowed single-file through each double quantum dot, causing them to emit photons in the microwave region of the spectrum. These photons then bounced off mirrors at each end of the cavity to build into a coherent beam of microwave light.

One advantage of the new maser is that the energy levels inside the dots can be fine-tuned to produce light at other frequencies, which cannot be done with other semiconductor lasers in which the frequency is fixed during manufacturing, Petta said. The larger the energy difference between the two levels, the higher the frequency of light emitted.

Claire Gmachl, who was not involved in the research and is Princeton’s Eugene Higgins Professor of Electrical Engineering and a pioneer in the field of semiconductor lasers, said that because lasers, masers and other forms of coherent light sources are used in communications, sensing, medicine and many other aspects of modern life, the study is an important one.

“In this paper the researchers dig down deep into the fundamental interaction between light and the moving electron,” Gmachl said. “The double quantum dot allows them full control over the motion of even a single electron, and in return they show how the coherent microwave field is created and amplified. Learning to control these fundamental light-matter interaction processes will help in the future development of light sources.”

Carbon nanotube finding could lead to flexible electronics with longer battery life

University of Wisconsin-Madison materials engineers have made a significant leap toward creating higher-performance electronics with improved battery life — and the ability to flex and stretch.

Led by materials science Associate Professor Michael Arnold and Professor Padma Gopalan, the team has reported the highest-performing carbon nanotube transistors ever demonstrated. In addition to paving the way for improved consumer electronics, this technology could also have specific uses in industrial and military applications.

In a paper published recently in the journal ACS Nano, Arnold, Gopalan and their students reported transistors with an on-off ratio that’s 1,000 times better and a conductance that’s 100 times better than previous state-of-the-art carbon nanotube transistors.

“Carbon nanotubes are very strong and very flexible, so they could also be used to make flexible displays and electronics that can stretch and bend, allowing you to integrate electronics into new places like clothing,” says Arnold. “The advance enables new types of electronics that aren’t possible with the more brittle materials manufacturers are currently using.”

Carbon nanotubes are single atomic sheets of carbon rolled up into a tube. As some of the best electrical conductors ever discovered, carbon nanotubes have long been recognized as a promising material for next-generation transistors, which are semiconductor devices that can act like an on-off switch for current or amplify current. This forms the foundation of an electronic device.

However, researchers have struggled to isolate purely semiconducting carbon nanotubes, which are crucial, because metallic nanotube impurities act like copper wires and “short” the device. Researchers have also struggled to control the placement and alignment of nanotubes. Until now, these two challenges have limited the development of high-performance carbon nanotube transistors.

Building on more than two decades of carbon nanotube research in the field, the UW-Madison team drew on cutting-edge technologies that use polymers to selectively sort out the semiconducting nanotubes, achieving a solution of ultra-high-purity semiconducting carbon nanotubes.

Previous techniques to align the nanotubes resulted in less-than-desirable packing density, or how close the nanotubes are to one another when they are assembled in a film. However, the UW-Madison researchers pioneered a new technique, called floating evaporative self-assembly, or FESA, which they described earlier in 2014 in the ACS journal Langmuir. In that technique, researchers exploited a self-assembly phenomenon triggered by rapidly evaporating a carbon nanotube solution.

The team’s most recent advance also brings the field closer to realizing carbon nanotube transistors as a feasible replacement for silicon transistors in computer chips and in high-frequency communication devices, which are rapidly approaching their physical scaling and performance limits.

“This is not an incremental improvement in performance,” Arnold says. “With these results, we’ve really made a leap in carbon nanotube transistors. Our carbon nanotube transistors are an order of magnitude better in conductance than the best thin film transistor technologies currently being used commercially while still switching on and off like a transistor is supposed to function.”

The researchers have patented their technology through the Wisconsin Alumni Research Foundation and have begun working with companies to accelerate the technology transfer to industry.

Research Alert: June 24, 2014

Tuesday, June 24th, 2014

imec joins Graphene Flagship

To coincide with Graphene Week 2014, the Graphene Flagship announced that today one of the largest-ever European research initiatives is doubling in size. Sixty-six new partners are being invited to join the consortium following the results of a €9 million competitive call. While most partners are universities and research institutes, the share of companies, mainly SMEs, involved is increasing. This shows the growing interest of economic actors in graphene. The partnership now includes more than 140 organizations from 23 countries. It is fully set to take “wonder material” graphene and related layered materials from academic laboratories to everyday use.

“Imec aims to show that graphene can form the basis of practical optoelectronic devices, such as high speed modulators and detectors, for use in low power optical interconnects,” said Cedric Huyghebaert, team leader of imec’s graphene group. “During the past five years, we have built a strong knowledge in graphene device making, focused on the generic building blocks like contacting, doping and gate engineering, which are essential to progress in any graphene application. This knowledge, combined with our unique experience in integrating novel materials into CMOS-processes, and our optoelectronic silicon waveguide platform, makes imec a very suitable place to develop hybrid-silicon-graphene optoelectronic devices compatible with CMOS.”

Collecting light with artificial “moth eyes”

All over the world researchers are investigating solar cells which imitate plant photosynthesis, using sunlight and water to create synthetic fuels such as hydrogen. Empa researchers have developed such a photoelectrochemical cell, recreating a moth’s eye to drastically increase its light collecting efficiency. The cell is made of cheap raw materials – iron and tungsten oxide.

Rust – iron oxide – could revolutionize solar cell technology. This usually unwanted substance can be used to make photoelectrodes which split water and generate hydrogen.  Sunlight is thereby directly converted into valuable fuel rather than first being used to generate electricity. Unfortunately, as a raw material iron oxide has its limitations. Although it is unbelievably cheap and absorbs light in exactly the wavelength region where the sun emits the most energy, it conducts electricity very poorly and must therefore be used in the form of an extremely thin film in order for the water splitting technique to work. The disadvantage of this is that these thin-films absorb too little of the sunlight shining on the cell.

Empa researchers Florent Boudoire and Artur Braun have now succeeded in solving this problem. A special microstructure on the photoelectrode surface literally gathers in sunlight and does not let it out again. The basis for this innovative structure are tiny particles of tungsten oxide which, because of their saturated yellow colour, can also be used for photoelectrodes. The yellow microspheres are applied to an electrode and then covered with an extremely thin nanoscale layer of iron oxide. When external light falls on the particle it is internally reflected back and forth, till finally all the light is absorbed. All the entire energy in the beam is now available to use for splitting the water molecules.

In principle the newly conceived microstructure functions like the eye of a moth, explains Florent Boudoire. The eyes of these night active creatures need to collect as much light as possible to see in the dark, and also must reflect as little as possible to avoid detection and being eaten by their enemies. The microstructure of their eyes especially adapted to the appropriate wavelength of light. Empa’s photocells take advantage of the same effect.

In order to recreate artificial moth eyes from metal oxide microspheres, Florent Boudoire sprays a sheet of glass with a suspension of plastic particles, each of which contains at its center a drop of tungsten salt solution. The particles lie on the glass like a layer of marbles packed close to each other. The sheet is placed in an oven and heated, the plastic material burns away and each drop of salt solution is transformed into the required tungsten oxide microsphere. The next step is to spray the new structure with an iron salt solution and once again heat it in an oven.

A silicon replacement? USC Viterbi School of Engineering overcomes major issue in carbon nanotube tech

When it comes to electronics, silicon may one day have to share the spotlight. In a paper recently published in Nature Communications, researchers from the USC Viterbi School of Engineering describe how they have overcome a major issue in carbon nanotube technology by developing a flexible, energy-efficient hybrid circuit combining carbon nanotube thin film transistors with other thin film transistors. This hybrid could take the place of silicon as the traditional transistor material used in electronic chips, since carbon nanotubes are more transparent, flexible, and can be processed at a lower cost.

Electrical engineering professor Dr. Chongwu Zhou and USC Viterbi graduate students Haitian Chen, Yu Cao, and Jialu Zhang developed this energy-efficient circuit by integrating carbon nanotube (CNT) thin film transistors (TFT) with thin film transistors comprised of indium, gallium and zinc oxide (IGZO).

“I came up with this concept in January 2013,” said Dr. Chongwu Zhou, professor in USC Viterbi’s Ming Hsieh Department of Electrical Engineering. “Before then, we were working hard to try to turn carbon nanotubes into n-type transistors and then one day, the idea came to me. Instead of working so hard to force nanotubes to do something that they are not good for, why don’t we just find another material which would be ideal for n-type transistors—in this case, IGZO—so we can achieve complementary circuits?”

Carbon nanotubes are so small that they can only be viewed through a scanning electron microscope. This hybridization of carbon nanotube thin films and IGZO thin films was achieved by combining their types, p-type and n-type, respectively, to create circuits that can operate complimentarily, reducing power loss and increasing efficiency. The inclusion of IGZO thin film transistors was necessary to provide power efficiency to increase battery life. If only carbon nanotubes had been used, then the circuits would not be power-efficient. By combining the two materials, their strengths have been joined and their weaknesses hidden.

Zhou likened the coupling of carbon nanotube TFTs and IGZO TFTs to the Chinese philosophy of yin and yang.

“It’s like a perfect marriage,” said Zhou. “We are very excited about this idea of hybrid integration and we believe there is a lot of potential for it.”

Research Alert: April 22, 2014

Tuesday, April 22nd, 2014

High performance, low-cost ultracapacitors built with graphene and carbon nanotubes

By combining the powers of two single-atom-thick carbon structures, researchers at the George Washington University’s Micro-propulsion and Nanotechnology Laboratory have created a new ultracapacitor that is both high performance and low cost.

The device capitalizes on the synergy brought by mixing graphene flakes with single-walled carbon nanotubes, two carbon nanostructures with complementary properties.

Ultracapacitors are souped-up energy storage devices that hold high amounts of energy and can also quickly release that energy in a surge of power. By combining the high energy-density properties of batteries with the high power-density properties of conventional capacitors, ultracapacitors can boost the performance of electric vehicles, handheld electronics, audio systems and more.

Single-walled carbon nanotubes and graphene both have unique and excellent electronic, thermal, and mechanical properties that make them attractive materials for designing new ultracapacitors, said Jian Li, first author on the paper. Many groups had explored the use of the two materials separately, but few had looked at combining them, he said.

“In our lab we developed an approach by which we can obtain both single-walled carbon nanotubes and graphene, so we came up with the idea to take advantage of the two promising carbon nanomaterials together,” added Michael Keidar, a professor in the Department of Mechanical and Aerospace Engineering in the School of Engineering and Applied Science at GW, and director of the Micro-propulsion and Nanotechnology Laboratory.

“Exotic” material is like a switch when super thin

Researchers from Cornell University and Brookhaven National Laboratory have shown how to switch a particular transition metal oxide, a lanthanum nickelate (LaNiO3), from a metal to an insulator by making the material less than a nanometer thick.

Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance and other exotic properties. These possibilities have scientists excited to understand everything about these materials, and to find new ways to control their properties at the most fundamental levels.

The team of researchers includes lead researcher Kyle Shen, associate professor of physics; first author Phil King, a recent Kavli postdoctoral fellow at Cornell now on the faculty at the University of St. Andrews; Darrell Schlom, the Herbert Fisk Johnson Professor of Industrial Chemistry; and co-authors Haofei Wei, Yuefeng Nie, Masaki Uchida, Carolina Adamo, and Shabo Zhu, and Xi He and Ivan Božović.

Using an extremely precise growth technique called molecular-beam epitaxy (MBE), King synthesized atomically thin samples of the lanthanum nickelate and discovered that the material changes abruptly from a metal to an insulator when its thickness is reduced to below 1 nanometer. When that threshold is crossed, its conductivity – the ability for electrons to flow through the material – switches off like a light, a characteristic that could prove useful in nanoscale switches or transistors, Shen said.

Using a one-of-a-kind system at Cornell, which integrates MBE film growth with a technique called angle-resolved photoemission spectroscopy (ARPES), King and colleagues mapped out how the motions and interactions of the electrons in the material changed across this threshold, varying the thickness of their oxide films atom by atom. They discovered that when the films were less than 3 nickel atoms thick, the electrons formed an unusual nanoscale order, akin to a checkerboard.

LG-Swiss researchers announce graphene membrane breakthrough

Researchers from LG Electronics (LG) and Swiss university ETH Zurich (Swiss Federal Institute of Technology Zurich) have developed a method to greatly increase the speed and efficient transmission of gas, liquid and water vapor through perforated graphene, a material that has seen an explosion of scientific interest in recent years. The findings open up the possibility in the future to develop highly efficient filters to treat air and water.

Graphene, a versatile material composed of a one-atom thick layer of graphite, is the thinnest, lightest and strongest compound currently known to man. It was first successfully isolated in 2004 and since then much research has been conducted with sheets of graphene, which have the unique property of being the only material where each single atom is exposed to a chemical reaction from both sides due to its 2D structure. Reliability and consistency when working with extremely delicate graphene has been a constant challenge for researchers.

Scientists from ETH Zurich and LG developed a reliable method for creating 2D membranes using chemical vapor deposition (CVD) optimized to grow graphene with minimal defects and cracks to form graphene layers thinner than 1nm (nanometer). Using a focused ion beam (FIB), the researchers then drilled nanopores in double layers of graphene to produce porous membranes with aperture diameters between less than 10nm and 1µm (micrometer).

Testing various sized perforations, the researchers found that their graphene membrane resulted in water permeance five- to sevenfold faster than conventional filtration membranes and transmission of water vapor several hundred times higher compared to today’s most advanced breathable textiles such as Gore-Tex. The findings of the LG-ETH Zurich team could lead to the development in the future of highly breathable materials that are also waterproof and more effective filters to separate dangerous gases from the air.

The Week in Review: Jan. 31, 2014

Friday, January 31st, 2014

The Obama Administration this week announced the selection of North Carolina State University to lead a public-private manufacturing innovation institute for next generation power electronics. Called the Next Generation Power Electronics Institute, the new consortium will provide shared facilities, equipment and testing to companies from the power electronics industry, focusing on small and medium-sized companies. The 18 companies already committed to the consortium include: ABB, APEI, Avogy, Cree, Delphi, Delta Products, DfR Solutions, Gridbridge, Hesse Mechantronics, II-VI, IQE, John Deere, Monolith Semiconductor, RF Micro Devices, Toshiba International, Transphorm, USCi and Vacon. The institute, backed by a $70 million investment from the Department of Energy, will focus on power electronics using wide bandgap (WBG) semiconductors, bringing together over 25 companies, universities and state and federal organizations.

Semiconductor Manufacturing International Corporation, China’s largest and most advanced semiconductor foundry, announced today that its 28nm technology has been process frozen and the company has successfully entered Multi Project Wafer (MPW) stage to support customer’s requirements on both 28nm PolySiON (PS) and 28nm high-k dielectrics metal gate (HKMG) processes. Over 100 IPs from multiple third party IP partners as well as SMIC’s internal IP team are prepared to serve various projects from worldwide design houses that have been showing interest in SMIC 28nm processes.

Researchers with the Lawrence Berkeley National Laboratory have developed a process-friendly technique that would enable the cooling of microprocessor chips through carbon nanotubes. Frank Ogletree, a physicist with Berkeley Lab’s Materials Sciences Division, led a study in which organic molecules were used to form strong covalent bonds between carbon nanotubes and metal surfaces. This improved by six-fold the flow of heat from the metal to the carbon nanotubes, paving the way for faster, more efficient cooling of computer chips. The technique is done through gas vapor or liquid chemistry at low temperatures, making it suitable for the manufacturing of computer chips.

With Korea expected to be the second largest region for fab construction spending in 2014, industry leaders will convene at SEMICON Korea 2014 in Seoul on February 12-14 to discuss the latest trends and technologies shaping the future of microelectronics manufacturing. Fab construction spending is expected to grow from about US$ 1.1billion in 2013 to $1.4 to 1.8 billion in 2014.  The 27th annual SEMICON Korea, the leading semiconductor technology event serving the region, will be held at COEX in Seoul. The event opens with a keynote speech by Dr. Roawen Chen from Qualcomm on “Mobile Innovation: Leading the Semiconductor Industry to a Smart, Connected World.”

Element Six, a developer of synthetic diamond supermaterials, today announced that the University of Strathclyde has successfully demonstrated two notable high-power laser research developments—the first ever tunable diamond Raman laser and the first continuous-wave (CW) laser—both using Element Six’s synthetic diamond material. These two achievements prove diamond’s viability as a material for solid-state laser engineering, even in the most demanding intracavity applications.

Novoset, LLC and Lonza introduced the Primaset ULL-950 and Primaset HTL-300 ultra-low loss and high temperature thermoset materials for the telecommunication and advanced semiconductor packaging industries. These thermoset resins are based on Cyanate ester (CE) chemistry.

Research Alert: Jan. 28, 2014

Tuesday, January 28th, 2014

New quantum dots herald a new era of electronics operating on a single-atom level

Physicists from the Institute of Experimental Physics at the Faculty of Physics at the University of Warsaw (FUW) have successfully created and studied two completely new types of the structures. The materials and elements used in the process make it wholly likely that solotronic devices may come into widespread use in the future.

The results, the Warsaw physicists have just published in Nature Communications, pave the way for developing the field of solotronics.

The researchers have presented two new systems with single magnetic ions: CdTe quantum dots with a cobalt atom, and cadmium selenide (CdSe) dots with a manganese atom.

The discovery made by physicists at the University of Warsaw demonstrates that other magnetic elements – such as chromium, iron and nickel – can be used in place of manganese. These elements do not have nuclear spin, which should make quantum dots that contain them easier to manipulate.

In quantum dots where tellurium is replaced by the lighter selenium, researchers observed that the duration for which information was remembered increased by an order of magnitude. This finding suggests that using lighter elements should prolong the time quantum dots containing single magnetic ions store information, perhaps even by several orders of magnitude.

“We have demonstrated that two quantum systems that were believed not to be viable in fact worked very effectively. This opens up a broad field in our search for other, previously rejected combinations of materials for quantum dots and magnetic ions,” concludes Dr. Wojciech Pacuski (FUW).

Cooling microprocessors with carbon nanotubes

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a “process friendly” technique that would enable the cooling of microprocessor chips through carbon nanotubes.

Frank Ogletree, a physicist with Berkeley Lab’s Materials Sciences Division, led a study in which organic molecules were used to form strong covalent bonds between carbon nanotubes and metal surfaces. This improved by six-fold the flow of heat from the metal to the carbon nanotubes, paving the way for faster, more efficient cooling of computer chips. The technique is done through gas vapor or liquid chemistry at low temperatures, making it suitable for the manufacturing of computer chips.

“We’ve developed covalent bond pathways that work for oxide-forming metals, such as aluminum and silicon, and for more noble metals, such as gold and copper,” says Ogletree, who serves as a staff engineer for the Imaging Facility at the Molecular Foundry, a DOE nanoscience center hosted by Berkeley Lab. “In both cases the mechanical adhesion improved so that surface bonds were strong enough to pull a carbon nanotube array off of its growth substrate and significantly improve the transport of heat across the interface.”

Although the approach used by Ogletree, Kaur and their colleagues substantially strengthened the contact between a metal and individual carbon nanotubes within an array, a majority of the nanotubes within the array may still fail to connect with the metal. The Berkeley team is now developing a way to improve the density of carbon nanotube/metal contacts. Their technique should also be applicable to single and multi-layer graphene devices, which face the same cooling issues.

“Part of our mission at the Molecular Foundry is to help develop solutions for technology problems posed to us by industrial users that also raise fundamental science questions,” Ogletree says. “In developing this technique to address a real-world technology problem, we also created tools that yield new information on fundamental chemistry.”

This work was supported by the DOE Office of Science and the Intel Corporation.

Research Alert: Nov. 26, 2013

Tuesday, November 26th, 2013

What can happen when graphene meets a semiconductor

For all the promise of graphene as a material for next-generation electronics and quantum computing, scientists still don’t know enough about this high-performance conductor to effectively control an electric current. Graphene, a one-atom-thick layer of carbon, conducts electricity so efficiently that the electrons are difficult to control. And control will be necessary before this wonder material can be used to make nanoscale transistors or other devices. A new study by a research group at the University of Wisconsin-Milwaukee (UWM) will help.

The researchers demonstrated that when electrons are rerouted at the interface of the graphene and its semiconducting substrate, they encounter what’s known as a Schottky barrier. If it’s deep enough, electrons don’t pass, unless rectified by applying an electric field – a promising mechanism for turning a graphene-based device on and off.

The group also found, however, another feature of graphene that affects the height of the barrier. Intrinsic ripples form on graphene when it is placed on top of a semiconductor.

Nanotubes can solder themselves

University of Illinois researchers have developed a way to heal gaps in wires too small for even the world’s tiniest soldering iron. Led by electrical and computer engineering professor Joseph Lyding and graduate student Jae Won Do, the Illinois team published its results in the journal Nano Letters.

Carbon nanotubes themselves are high-quality conductors, but creating single tubes suitable to serve as transistors is very difficult. Arrays of nanotubes are much easier to make, but the current has to hop through junctions from one nanotube to the next, slowing it down. In standard electrical wires, such junctions would be soldered, but how could the gaps be bridged on such a small scale?

“It occurred to me that these nanotube junctions will get hot when you pass current through them,” said Lyding, “kind of like faulty wiring in a home can create hot spots. In our case, we use these hot spots to trigger a local chemical reaction that deposits metal that nano-solders the junctions.”

The nano-soldering process is simple and self-regulating. A carbon nanotube array is placed in a chamber pumped full of the metal-containing gas molecules. When a current passes through the transistor, the junctions heat because of resistance as electrons flow from one nanotube to the next. The molecules react to the heat, depositing the metal at the hot spots and effectively “soldering” the junctions. Then the resistance drops, as well as the temperature, so the reaction stops.

U.S. government awards AMD contract to research interconnect architectures

AMD today announced that it was selected for an award of $3.1 million for a research project associated with the U.S. Department of Energy (DOE) Extreme-Scale Computing Research and Development Program, known as “DesignForward.” The DOE award is an expansion of work started as part of another two-year award AMD received in 2012 called “FastForward.” The FastForward award aims to accelerate the research and development of processor and memory technologies needed to support extreme-scale computing. The DesignForward award supports the research of the interconnect architectures and technologies needed to support the data transfer capabilities in extreme-scale computing environments.

DesignForward is a jointly funded collaboration between the DOE Office of Science and the U.S. National Nuclear Security Administration (NNSA) to accelerate the research and development of critical technologies needed for extreme-scale computing, on the path toward Exascale computing. Exascale supercomputers are expected to be capable of performing computation hundreds of times faster than today’s fastest computers, with only slightly higher power utilization. Exascale supercomputers are designed to break through the current limitations of today’s supercomputers by dramatically reducing the length of run time required to perform calculations and improving the capability to perform detailed simulations, modeling, and analyses of complex systems.

In order to achieve this dramatic increase in computing capability while maintaining low power consumption, leaps in research and development need to be advanced in all aspects of computing.

Research Alert: Nov. 19, 2013

Tuesday, November 19th, 2013

Graphene nanoribbons for ‘reading’ DNA

If we wanted to count the number of people in a crowd, we could make on the fly estimates, very likely to be imprecise, or we could ask each person to pass through a turnstile. The latter resembles the model that EPFL researchers have used for creating a “DNA reader” that is able to detect the passage of individual DNA molecules through a tiny hole: a nanopore with integrated graphene transistor.

Direct electrical readout from the graphene transistors is used to detect DNA translocation events. Nanopore, DNA and the graphene nanoribbon are shown in this schematic (which is not to scale).

The DNA molecules are diluted in a solution containing ions and are driven by an electric field through a membrane with a nanopore. When the molecule goes through the orifice, it provokes a slight perturbation to the field, detectable not only by the modulations in ionic current but also by concomitant modulation in the graphene transistor current. Based on this information, it is possible to determine whether a DNA molecule has passed through the membrane or not.

This system is based on a method that has been known for over a dozen years. The original technique was not as reliable since it presented a number of shortcomings such as clogging pores and lack of precision, among others. “We thought that we would be able to solve these problems by creating a membrane as thin as possible while maintaining the orifice’s strength,” said Aleksandra Radenovic from the Laboratory of Nanoscale Biology at EPFL. Together with Floriano Traversi, postdoctoral student, and colleagues from the Laboratory of Nanoscale Electronics and Structures, she came across the material that turned out to be both the strongest and most resilient: graphene, which consists of a single layer of carbon molecules. The strips of graphene or nanoribbons used in the experiment were produced at EPFL, thanks to the work carried out at the Center for Micro Nanotechnology (CMI) and the Center for Electron Microscopy (CIME).

“Through an amazing coincidence, continued the researcher, the graphene layer’s thickness measures 0.335 nm, which exactly fits the gap existing between two DNA bases, whereas in the materials used so far there was a 15 nm thickness.” As a result, while previously it was not possible to individually analyze the passage of DNA bases through these “long” tunnels – at a molecular scale –, the new method is likely to provide a much higher precision. Eventually, it could be used for DNA sequencing.

However they are not there yet. In only five milliseconds, up to 50,000 DNA bases can pass through the pores. The electric output signal is not clear enough for “reading” the live sequence of the DNA strand passage. “However, the possibility of detecting the passage of DNA with graphene nanoribbons is a breakthrough as well as a significant opportunity”, said Aleksandra Radenovic. She noted that, for example, the device is also able to detect the passage of other kinds of proteins and provide information on their size and/or shape.

Taking a new look at carbon nanotubes

Despite their almost incomprehensibly small size – a diameter about one ten-thousandth the thickness of a human hair – single-walled carbon nanotubes come in a plethora of different “species,” each with its own structure and unique combination of electronic and optical properties. Characterizing the structure and properties of an individual carbon nanotube has involved a lot of guesswork – until now.

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have developed a technique that can be used to identify the structure of an individual carbon nanotube and characterize its electronic and optical properties in a functional device.

New way to dissolve semiconductors holds promise for future of electronics

Semiconductors could become even more versatile as researchers make headway on a novel, inexpensive way to turn them into thin films. Their report on a new liquid that can quickly dissolve nine types of key semiconductors appears in the Journal of the American Chemical Society.

Richard L. Brutchey and David H. Webber note that making low-cost, semiconducting thin films on a large scale holds promise for improving a number of electronic applications, including solar cells. The problem has been finding a liquid that can dissolve semiconductors so that they can be subsequently solution-processed using inexpensive methods. Hydrazine can do the trick for many of these materials, but as a compound that is sometimes used in rocket fuel, it is explosive and highly toxic. It’s also a poor option for making semiconducting thin films en masse. Brutchey and his team decided to search for a safer solution.

They found an answer in a mixture of two compounds that could dissolve a set of important semiconducting materials called chalcogenides at room temperature and normal air pressure. The researchers state, “We believe these initial results indicate that the chemistry can be further extended to other families of chalcogenide materials and may hold promise for applications that would benefit from solution deposition of semiconductor thin films.”

Research News: Nov. 5, 2013

Tuesday, November 5th, 2013

Imec, a nanoelectronics research center, announced today that it has successfully demonstrated the first III-V compound semiconductor FinFET devices integrated epitaxially on 300mm silicon wafers, through a unique silicon fin replacement process. The achievement illustrates progress toward 300mm and future 450mm high-volume wafer manufacturing of advanced heterogeneous CMOS devices, monolithically integrating high-density compound semiconductors on silicon. The breakthrough not only enables continual CMOS scaling down to 7nm and below, but also enables new heterogeneous system opportunities in hybrid CMOS-RF and CMOS-optoelectronics. “To our knowledge, this is the world’s first functioning CMOS compatible IIIV FinFET device processed on 300mm wafers,” stated An Steegen, senior vice president core CMOS at imec. “This is an exciting accomplishment, demonstrating the technology as a viable next-generation alternative for the current state-of-the-art Si-based FinFET technology in high volume production.”

Columbia Engineering researchers have experimentally demonstrated for the first time that it is possible to electrically contact an atomically thin two-dimensional (2D) material only along its one-dimensional (1D) edge, rather than contacting it from the top, which has been the conventional approach. With this new contact architecture, they have developed a new assembly technique for layered materials that prevents contamination at the interfaces, and, using graphene as the model 2D material, show that these two methods in combination result in the cleanest graphene yet realized. The study is published in Science on November 1, 2013. The researchers fully encapsulated the 2D graphene layer in a sandwich of thin insulating boron nitride crystals, employing a new technique in which crystal layers are stacked one-by-one. Once they created the stack, they etched it to expose the edge of the graphene layer, and then evaporated metal onto the edge to create the electrical contact. By making contact along the edge, the team realized a 1D interface between the 2D active layer and 3D metal electrode. And, even though electrons entered only at the 1D atomic edge of the graphene sheet, the contact resistance was remarkably low, reaching 100 Ohms per micron of contact width—a value smaller than what can be achieved for contacts at the graphene top surface.

UPV/EHU-University of the Basque Country researchers have developed and patented a new source of light emitter based on boron nitride nanotubes and suitable for developing high-efficiency optoelectronic devices. Scientists are usually after defect-free nano-structures. Yet in this case the UPV/EHU researcher Angel Rubio and his collaborators have put the structural defects in boron nitride nanotubes to maximum use. The outcome of his research is a new light-emitting source that can easily be incorporated into current microelectronics technology. The research has also resulted in a patent.


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