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IXYS Corporation (NASDAQ:IXYS), a global manufacturer of power semiconductors and integrated circuits (ICs) for energy efficiency, power management, transportation, medical, and motor control applications, today announced a new power semiconductor product line: 200V Ultra-Junction X3-Class HiPerFET Power MOSFETs. The current ratings range from 36A to 300A; a broad selection of devices are available in a number of international standard packages.

Fabricated using a charge compensation principle and IXYS’ own process technology, these new MOSFETs exhibit the lowest on-state resistances in the industry (3.5 milliohms in the SOT-227 package and 4 milliohms in the TO-264, for example). Along with gate charges as low as 21 nanocoulombs, these devices enable highest power densities and energy efficiencies in a wide variety of high-speed power conversion applications.

The fast body diodes of the devices are optimized and have low reverse recovery charge and time, thereby suppressing transients and enabling low-noise, high-efficiency power switching. Their low reverse recovery charge and time also boost efficiencies. In addition, these new MOSFETs are avalanche capable and exhibit a superior dv/dt performance (up to 20V/ns).

Targeted applications include synchronous rectification, battery chargers for light electric vehicles (LEVs), motor control (48V-110V systems), DC-DC converters, uninterruptible power supplies, electric forklifts, inverters, power solid state relays, and Class-D audio amplifiers.

The new 200V X3-Class Power MOSFETs with HiPerFET body diodes are available in the following international standard size packages: TO-3P, TO-220 (overmolded or standard), TO-247, PLUS247, TO-252, TO-263, TO-264, TO-268HV, SOT-227. Some example part numbers include IXFP36N20X3, IXFA72N20X3, IXFH90N20X3 and IXFN300N20X3, with current ratings of 36A, 72A, 90A and 300A, respectively.

Additional product information can be obtained by visiting the IXYS website at http://www.ixys.com or by contacting the company directly.

Leti, a research institute of CEA Tech, will demonstrate at CES 2018 its new wristband that measures physical indicators of a range of conditions, including sleep apnea, dehydration and dialysis-treatment response. 

APNEAband provides accurate, real-time detection of sleep-apnea events caused by pauses in breathing or shallow breaths during sleep. The wristband measures heart rate, variation in the time interval between heartbeats, oxygen saturation levels in the blood and stress level. The combination of these four indicators helps physicians make a complete and reliable medical diagnosis of sleep apnea.

“This small wristband eliminates the need to spend the night in a medical lab hooked up to sensors and equipment that measure these key indicators,” said Alexandre Thermet, Leti healthcare industrial partnership manager in the U.S. “APNEAband brings a safe, easy-to-use, affordable and non-invasive solution to detect sleep apnea at home.”

Working with Prof. Jean-Louis Pepin and his team at Grenoble Alpes University and INSERM from the Physiology Laboratory in Grenoble CHU’s hospital, Leti designed, developed and validated an advanced software technology that efficiently extracts and screens health parameters relevant to sleep apnea.  Pr. Pepin, a principal clinical-trial investigator at Grenoble CHU Hospital, and its team provided medical guidelines to support this sleep-apnea project.

APNEAband’s embedded technology can be applied to detect and track various other health conditions, such as acute mountain sickness, dehydration, dialysis treatment response, chronic pain, epileptic seizures, phobia and panic disorder. The wristband’s cardiac-coherence biofeedback also helps people who want to achieve total relaxation with simple breathing exercises. Possible applications also include detecting work-related stress or hot flashes and stress, while playing video games.

A new technique developed by researchers at Technische Universität München, Forschungszentrum Jülich, and RWTH Aachen University, published in Elsevier’s Materials Today, provides a unique insight into how the charging rate of lithium ion batteries can be a factor limiting their lifetime and safety.

State-of-the-art lithium ion batteries are powering a revolution in clean transport and high-end consumer electronics, but there is still plenty of scope for improving charging time. Currently, reducing charging time by increasing the charging current compromises battery lifetime and safety.

“The rate at which lithium ions can be reversibly intercalated into the graphite anode, just before lithium plating sets in, limits the charging current,” explains Johannes Wandt, PhD, of Technische Universität München (TUM).

Lithium ion batteries consist of a positively charged transition metal oxide cathode and a negatively charged graphite anode in a liquid electrolyte. During charging, lithium ions move from the cathode (deintercalate) to the anode (intercalate). However if the charging rate is too high, lithium ions deposit as a metallic layer on the surface of the anode rather than inserting themselves into the graphite. “This undesired lithium plating side reaction causes rapid cell degradation and poses a safety hazard,” Dr. Wandt added.

Dr. Wandt and Dr. Hubert A. Gasteiger, Chair of Technical Electrochemistry at TUM, along with colleagues from Forschungzentrum Jülich and RWTH Aachen University, set out to develop a new tool to detect the actual amount of lithium plating on a graphite anode in real-time. The result is a technique the researchers call operando electron paramagnetic resonance (EPR).

“The easiest way to observe lithium metal plating is by opening a cell at the end of its lifetime and checking visually by eye or microscope,” said Dr. Wandt. “There are also nondestructive electrochemical techniques that give information on whether lithium plating has occurred during battery charging.”

Neither approach, however, provides much if any information about the onset of lithium metal plating or the amount of lithium metal present during charging. EPR, by contrast, detects the magnetic moment associated with unpaired conduction electrons in metallic lithium with very high sensitivity and time resolution on the order of a few minutes or even seconds.

“In its present form, this technique is mainly limited to laboratory-scale cells, but there are a number of possible applications,” explains Dr. Josef Granwehr of Forschungzentrum Jülich and RWTH Aachen University. “So far, the development of advanced fast charging procedures has been based mainly on simulations but an analytical technique to experimentally validate these results has been missing. The technique will also be very interesting for testing battery materials and their influence on lithium metal plating. In particular, electrolyte additives that could suppress or reduce lithium metal plating.”

Dr. Wandt highlights that fast charging for electric vehicles could be a key application to benefit from further analysis of the work.

Until now, there has been no analytical technique available that can directly determine the maximum charging rate, which is a function of the state of charge, temperature, electrode geometry, and other factors, before lithium metal plating starts. The new technique could provide a much-needed experimental validation of frequently used computational models, as well as a means of investigating the effect of new battery materials and additives on lithium metal plating.

The researchers are now working with other collaborators to benchmark their experimental results against numerical simulations of the plating process in simple model systems.

“Our goal is to develop a toolset that facilitates a practical understanding of lithium metal plating for different battery designs and cycling protocols,” explains Dr. Rüdiger-A. Eichel of Forschungzentrum Jülich and RWTH Aachen University.

Researchers at Aalto University, Finland, have developed a biosensor that enables creating a range of new easy-to-use health tests similar to home pregnancy tests. The plasmonic biosensor can detect diseased exosomes even by the naked eye. Exosomes, important indicators of health conditions, are cell-derived vesicles that are present in blood and urine.

A rapid analysis by biosensors helps recognize inflammatory bowel diseases, cancer and other diseases rapidly and start relevant treatments in time. In addition to using discovery in biomedicine, industry may use advanced applications in energy.

Researchers created a new biosensor by depositing plasmonic metaparticles on a black, physical body that absorbs all incident electromagnetic radiation. A plasmon is a quantum of plasma oscillation. Plasmonic materials have been used for making objects invisible in scientific tests. They efficiently reflect and absorb light. Plasmonic materials are based on the effective polarizabilities of metallic nanostructures.

The carriers containing Ag nanoparticles are covered with various dielectrics of AlN, SiO2 and the composites thereof that are placed on a black background to enhance the reflectivity contrast of various colours at a normal angle of incidence. Credit: Aalto University

The carriers containing Ag nanoparticles are covered with various dielectrics of AlN, SiO2 and the composites thereof that are placed on a black background to enhance the reflectivity contrast of various colours at a normal angle of incidence. Credit: Aalto University

“It is extraordinary that we can detect diseased exosomes by the naked eye. The conventional plasmonic biosensors are able to detect analytes solely at a molecular level. So far, the naked-eye detection of biosamples has been either rarely considered or unsuccessful”, says Professor Mady Elbahri from Aalto University.

Plasmonic dipoles are famous for their strong scattering and absorption. Dr. Shahin Homaeigohar and Moheb Abdealziz from Aalto University explain that the research group has succeeded in demonstrating the as-yet unknown specular reflection and the Brewster effect of ultrafine plasmonic dipoles on a black body host.

“We exploited it as the basis of new design rules to differentiate diseased human serum exosomes from healthy ones in a simple manner with no need to any specialized equipment”, says Dr. Abdou Elsharawy from the University of Kiel.

The novel approach enables a simple and cost-effective design of a perfect colored absorber and creation of vivid interference plasmonic colors.

According to Elbahri, there is no need to use of sophisticated fabrication and patterning methods. It enables naked-eye environmental and bulk biodetection of samples with a very minor change of molecular polarizability of even 0.001%.

Think keeping your coffee warm is important? Try satellites. If a satellite’s temperature is not maintained within its optimal range, its performance can suffer which could mean it could be harder to track wildfires or other natural disasters, your Google maps might not work and your Netflix binge might be interrupted. This might be prevented with a new material recently developed by USC Viterbi School of Engineering engineers.

When satellites travel behind the Earth, the Earth can block the sun’s rays from reaching the satellites—cooling them down. In space, a satellite can face extreme temperature variation as much as 190 to 260 degrees Fahrenheit. It’s long been a challenge for engineers to keep satellite temperatures from fluctuating wildly. Satellites have conventionally used one of two mechanisms: physical “shutters” or heat pipes to regulate heat. Both solutions can deplete on-board power reserves. Even with solar power, the output is limited. Furthermore, both solutions add mass, weight and design complexity to satellites, which are already quite expensive to launch.

Taking cues from humans who have a self-contained system to manage internal temperature through homeostasis, a team of researchers including Michelle L. Povinelli, a Professor in the Ming Hsieh Department of Electrical Engineering at the USC Viterbi School of Engineering, and USC Viterbi students Shao-Hua Wu and Mingkun Chen, along with Michael T. Barako, Vladan Jankovic, Philip W.C. Hon and Luke A. Sweatlock of Northrop Grumman, developed a new material to self-regulate the temperature of the satellite. The team of engineers with expertise in optics, photonics, and thermal engineering developed a hybrid structure of silicon and vanadium dioxide with a conical design to better control the radiation from the body of the satellite. It’s like a textured skin or coating.

Vanadium dioxide functions as what is known as a “phase-change” material. It acts in two distinct ways: as an insulator at low temperatures and a conductor at high temperatures. This affects how it radiates heat. At over 134 degrees Fahrenheit (330 degrees Kelvin), it radiates as much heat as possible to cool the satellite down. At about two degrees below this, the material shuts off the heat radiation to warm the satellite up. The material’s conical structure (almost like a prickly skin) is invisible to the human eye at about less than half the thickness of a single human hair–but has a distinct purpose of helping the satellite to switch its radiation on and off very effectively.

Results

The hybrid material developed by USC and Northrop Grumman is twenty times better at maintaining temperature than silicon alone. Importantly, passively regulating heat and temperature of satellites could increase the life span of the satellites by reducing the need to expend on-board power.

Applications on Earth

Besides use on a satellite, the material could also be used on Earth for thermal management. It could be applied to a building over a large area to more efficiently maintain a building’s temperature.

The study, “Thermal homeostasis using microstructured phase-change materials,” is published in Optica. The research was funded by Northrop Grumman and the National Science Foundation. This development is part of a thematic research effort between Northrop Grumman, NG Next Basic Research and USC known as the Northrop Grumman Institute of Optical Nanomaterials and Nanophotonics (NG-ION2).

The researchers are now working on developing the material in the USC microfabrication facility and will likely benefit from the new capabilities in the recently-dedicated John D. O’Brien Nanofabrication Laboratory in the USC Michelson Center for Convergent Bioscience.

aveni S.A., developer and manufacturer of market-disrupting wet deposition technologies and chemistries for 2D interconnects and 3D through silicon via packaging, today announced it has obtained results that strongly support the continued use of copper in the back end of line (BEOL) for advanced interconnects, at and beyond the 5nm technology node.

“In this 20th-anniversary year of copper integration, our results validate the comments made by IBM Research Fellow Dan Edelstein in his keynote presentation at the recent IEEE Nanotechnology Symposium, discussing that copper integration is here to stay,” noted Bruno Morel, aveni CEO.

As devices inevitably continue to shrink to meet (and create) market demand, designers are exploring alternative integration schemes, not only for the front end of line, but also the BEOL. This includes, most notably, replacing the copper in dual-damascene interconnects, to compensate for the increased resistance-capacitance (RC) delay that accompanies the thinner copper wires and adversely affects device speed. Proposed replacement options for copper are cobalt, the most likely candidate, or more exotic materials like ruthenium, graphene or carbon nanotubes.

Advanced dual-damascene structures employ an atomic layer deposition tantalum nitride (TaN) copper diffusion barrier, a thin chemical vapor deposition (CVD) cobalt liner, and the electroplated copper fill layer, which makes up most of the wiring. Earlier generations (≥7nm node) also use a physical vapor deposition (PVD) copper seed layer between the cobalt and copper fill, but advanced devices are phasing out this film due to marginal seed coverage and integration hurdles.

Of particular interest is the thin TaN barrier, which prevents copper from diffusing into and poisoning the device. The integrity of the thin cobalt liner (on top of TaN) is critical to ensuring that the barrier functions properly. The reduced thickness of cobalt liners for the 5nm technology node is approaching 3nm, reducing process flexibility for conventional approaches to copper plating.

In a recent study, aveni compared its Sao™ alkaline-based copper electroplating chemistry performance with a conventional, commercially available acidic copper plating chemistry. The samples to be plated were 3nm CVD cobalt over TaN. The study results showed that the acidic copper chemistry attacked the cobalt liner, causing the plating chemistry to react with the underlying TaN film and form tantalum oxide (TaOx). TaOx formation is another failure mode of devices, because it creates an effective open circuit that prevents current flow.

With aveni’s Sao chemistry, the cobalt remained intact and TaOx was not formed, which enables the extension of copper interconnects to process nodes at 5nm and below.

Frédéric Raynal, chief technical officer at aveni, commented, “We were extremely excited about these results, because they substantiate our position that Sao alkaline-based chemistry for copper electroplating is superior to acidic chemistries, especially with the thinner cobalt liners used in advanced nodes.”

aveni will publish the complete findings in a report in early 2018.

 

In a major step toward making a quantum computer using everyday materials, a team led by researchers at Princeton University has constructed a key piece of silicon hardware capable of controlling quantum behavior between two electrons with extremely high precision. The study was published Dec. 7 in the journal Science.

The researchers demonstrated the ability to control with precision the behavior of two silicon-based quantum bits, or qubits, paving the way for making complex, multi-qubit devices using technology that is less expensive and easier to manufacture than other approaches. Credit: David Zajac, Princeton University

The researchers demonstrated the ability to control with precision the behavior of two silicon-based quantum bits, or qubits, paving the way for making complex, multi-qubit devices using technology that is less expensive and easier to manufacture than other approaches. Credit: David Zajac, Princeton University

The team constructed a gate that controls interactions between the electrons in a way that allows them to act as the quantum bits of information, or qubits, necessary for quantum computing. The demonstration of this nearly error-free, two-qubit gate is an important early step in building a more complex quantum computing device from silicon, the same material used in conventional computers and smartphones.

“We knew we needed to get this experiment to work if silicon-based technology was going to have a future in terms of scaling up and building a quantum computer,” said Jason Petta, a professor of physics at Princeton University. “The creation of this high-fidelity two-qubit gate opens the door to larger scale experiments.”

Silicon-based devices are likely to be less expensive and easier to manufacture than other technologies for achieving a quantum computer. Although other research groups and companies have announced quantum devices containing 50 or more qubits, those systems require exotic materials such as superconductors or charged atoms held in place by lasers.

Quantum computers can solve problems that are inaccessible with conventional computers. The devices may be able to factor extremely large numbers or find the optimal solutions for complex problems. They could also help researchers understand the physical properties of extremely small particles such as atoms and molecules, leading to advances in areas such as materials science and drug discovery.

Building a quantum computer requires researchers to create qubits and couple them to each other with high fidelity. Silicon-based quantum devices use a quantum property of electrons called “spin” to encode information. The spin can point either up or down in a manner analogous to the north and south poles of a magnet. In contrast, conventional computers work by manipulating the electron’s negative charge.

Achieving a high-performance, spin-based quantum device has been hampered by the fragility of spin states — they readily flip from up to down or vice versa unless they can be isolated in a very pure environment. By building the silicon quantum devices in Princeton’s Quantum Device Nanofabrication Laboratory, the researchers were able to keep the spins coherent — that is, in their quantum states — for relatively long periods of time.

To construct the two-qubit gate, the researchers layered tiny aluminum wires onto a highly ordered silicon crystal. The wires deliver voltages that trap two single electrons, separated by an energy barrier, in a well-like structure called a double quantum dot.

By temporarily lowering the energy barrier, the researchers allow the electrons to share quantum information, creating a special quantum state called entanglement. These trapped and entangled electrons are now ready for use as qubits, which are like conventional computer bits but with superpowers: while a conventional bit can represent a zero or a 1, each qubit can be simultaneously a zero and a 1, greatly expanding the number of possible permutations that can be compared instantaneously.

“The challenge is that it’s very difficult to build artificial structures small enough to trap and control single electrons without destroying their long storage times,” said David Zajac, a graduate student in physics at Princeton and first-author on the study. “This is the first demonstration of entanglement between two electron spins in silicon, a material known for providing one of the cleanest environments for electron spin states.”

The researchers demonstrated that they can use the first qubit to control the second qubit, signifying that the structure functioned as a controlled NOT (CNOT) gate, which is the quantum version of a commonly used computer circuit component. The researchers control the behavior of the first qubit by applying a magnetic field. The gate produces a result based on the state of the first qubit: If the first spin is pointed up, then the second qubit’s spin will flip, but if the first spin is down, the second one will not flip.

“The gate is basically saying it is only going to do something to one particle if the other particle is in a certain configuration,” Petta said. “What happens to one particle depends on the other particle.”

The researchers showed that they can maintain the electron spins in their quantum states with a fidelity exceeding 99 percent and that the gate works reliably to flip the spin of the second qubit about 75 percent of the time. The technology has the potential to scale to more qubits with even lower error rates, according to the researchers.

“This work stands out in a worldwide race to demonstrate the CNOT gate, a fundamental building block for quantum computation, in silicon-based qubits,” said HongWen Jiang, a professor of physics and astronomy at the University of California-Los Angeles. “The error rate for the two-qubit operation is unambiguously benchmarked. It is particularly impressive that this extraordinarily difficult experiment, which requires a sophisticated device fabrication and an exquisite control of quantum states, is done in a university lab consisting of only a few researchers.”

SUNY Polytechnic Institute (SUNY Poly) Professor of Nanoengineering Bin Yu has been named a Fellow of the National Academy of Inventors (NAI), the organization announced Tuesday. Election to NAI Fellow status is one of the highest professional accolades bestowed solely to academic inventors who have demonstrated a prolific spirit of innovation in creating or facilitating outstanding inventions that have made a tangible impact on quality of life, economic development, and the welfare of society.

“I am proud to congratulate Dr. Yu on his selection as Fellow of the NAI, which is a strong reflection of his research that has helped to advance cutting-edge nanotechnologies,” said SUNY Poly Interim President Dr. Bahgat Sammakia. “Dr. Yu’s numerous patents and continued SUNY Poly-based research in exciting areas such as nanomaterials and advanced nano-devices continues to hold promise for further developments that can enhance energy efficiency and boost computing speeds to improve the technologies that our society relies on each day.”

Those elected to the rank of NAI Fellow are named inventors on U.S. patents and were nominated by their peers for outstanding contributions to innovation, as well as for patents and licensing, innovative discovery and technology, and providing significant impact on society.

Dr. Yu has a number of significant accomplishments in the areas of nano electronic devices, nano-based sensors, nano-based energy harvesting, emerging data storage devices, next-generation interconnects, and smart nano-manufacturing, including work as the lead researcher for the world’s first 10 nm gate-length 3D transistor FinFET (IEEE-IEDM’2002), and for the world’s first THz silicon logic switch (IEEE-IEDM’2001).

Dr. Yu is the recipient of multiple awards and honors, including the NASA Innovation Award and IBM Faculty Award, and was ranked #3 by the National Science Foundation for Supported Investigators with Most Patents in 2011; as an inventor, he holds more than 300 awarded U.S. patents.

“I am honored that I have been selected to become a National Academy of Inventors Fellow, a powerful recognition of the work undertaken at SUNY Poly which can help to advance technology based on a wide variety of applied nanostrucutures,” said Dr. Yu. “I congratulate my fellow inductees and appreciate the acknowledgement of the importance of these research contributions that have led to more than 300 U.S. patents. I look forward to continuing to pursue efforts utilizing SUNY Poly’s state-of-the-art resources and capabilities for research related to nano-inspired technologies targeted for the next-generation of computing, sensing, and energy generation, as well as research related to emerging nanomaterials for smart nanomanufacturing.”

Dr. Yu has published books and book chapters on topics ranging from graphene-based electronics to 2D layered semiconductor-based emerging solar photovoltaics. He has also served as Editor of IEEE Electron Device Letters from 2001-2007, Associate Editor of IEEE Transactions on Nanotechnology from 2007-2010, and is currently an Editorial Board Member for Nano-Micro Letters and an Editorial Advisory Board Member for Nanoelectronics and Spintronics, among other leadership positions. Dr. Yu has been invited as a speaker to more than 100 highlight/invited talks, seminars, and tutorials to international conferences, universities, industry national labs, and professional societies. He is also an Institute of Electrical and Electronics Engineers (IEEE) Fellow and IEEE Electronic Device Society Distinguished Lecturer. More information about Dr. Yu’s background can be found here.

With the election of the 2017 class there are now 912 NAI Fellows, representing over 250 research universities and governmental and non-profit research institutes. The 2017 Fellows are named inventors on nearly 6,000 issued U.S. patents, bringing the collective patents held by all NAI Fellows to more than 32,000 issued U.S. patents.

Included among all NAI Fellows are more than 100 presidents and senior leaders of research universities and non-profit research institutes; 439 members of the National Academies of Sciences, Engineering, and Medicine; 36 inductees of the National Inventors Hall of Fame; 52 recipients of the U.S. National Medal of Technology and Innovation and U.S. National Medal of Science; 29 Nobel Laureates; 261 AAAS Fellows; 168 IEEE Fellows; and 142 Fellows of the American Academy of Arts & Sciences, among other awards and distinctions.

In April 2018 the 2017 NAI Fellows will be inducted as part of the Seventh Annual NAI Conference of the National Academy of Inventors at the Mayflower Hotel, Autograph Collection in Washington, D.C., and Andrew H. Hirshfeld, U.S. Commissioner for Patents, will provide the keynote address for the induction ceremony.

The 2017 class of NAI Fellows was evaluated by the 2017 Selection Committee, which included 18 members comprising NAI Fellows, U.S. National Medals recipients, National Inventors Hall of Fame inductees, members of the National Academies of Sciences, Engineering, and Medicine and senior officials from the USPTO, National Institute of Standards and Technology, Association of American Universities, American Association for the Advancement of Science, Association of Public and Land-grant Universities, Association of University Technology Managers, and National Inventors Hall of Fame, among other organizations.

A team of University of Alberta engineers developed a new way to produce electrical power that can charge handheld devices or sensors that monitor anything from pipelines to medical implants. The discovery sets a new world standard in devices called triboelectric nanogenerators by producing a high-density DC current–a vast improvement over low-quality AC currents produced by other research teams.

Jun Liu, a PhD student working under the supervision of chemical engineering professor Thomas Thundat, was conducting research unrelated to these tiny generators, using a device called an atomic force microscope. It provides images at the atomic level using a tiny cantilever to “feel” an object, the same way you might learn about an object by running a finger over it. Liu forgot to press a button that would apply electricity to the sample–but he still saw a current coming from the material.

“I didn’t know why I was seeing a current,” he recalled.

One theory was that it was an anomaly or a technical problem, or interference. But Liu wanted to get to the bottom of it. He eventually pinned the cause on the friction of the microscope’s probe on the material. It’s like shuffling across a carpet then touching someone and giving them a shock.

It turns out that the mechanical energy of the microscope’s cantilever moving across a surface can generate a flow of electricity. But instead of releasing all the energy in one burst, the U of A team generated a steady current.

“Many other researchers are trying to generate power at the prototype stages but their performances are limited by the current density they’re getting–that is the problem we solved,” said Liu.

“This is big,” said Thundat. “So far, what other teams have been able to do is to generate very high voltages, but not the current. What Jun has discovered is a new way to get continuous flow of high current.”

The discovery means that nanoscale generators have the potential to harvest power for electrical devices based on nanoscale movement and vibration: an engine, traffic on a roadway–even a heartbeat. It could lead to technology with applications in everything from sensors used to monitor the physical strength of structures such as bridges or pipelines, the performance of engines or wearable electronic devices.

Liu said the applications are limited only by imagination.

University of Alabama at Birmingham physicists have taken the first step in a five-year effort to create novel compounds that surpass diamonds in heat resistance and nearly rival them in hardness.

They are supported by a five-year, $20 million National Science Foundation award to create new materials and improve technologies using the fourth state of matter — plasma.

Plasma — unlike the other three states of matter, solid, liquid and gas — does not exist naturally on Earth. This ionized gaseous substance can be made by heating neutral gases. In the lab, Yogesh Vohra, a professor and university scholar in the UAB Department of Physics, uses plasma to create thin diamonds film. Such films have many potential uses, such as coatings to make artificial joints long-lasting or to maintain the sharpness of cutting tools, developing sensors for extreme environments or creating new super-hard materials.

To make a diamond film, Vohra and colleagues stream a mix of gases into a vacuum chamber, heating them with microwaves to create plasma. The low pressure in the chamber is equivalent to the atmosphere 14 miles above the Earth’s surface. After four hours, the vapor has deposited a thin diamond film on its target.

In a paper in the journal Materials, Vohra and colleagues in the UAB College of Arts and Sciences investigated how the addition of boron, while making a diamond film, changed properties of the diamond material.

It was already known that, if the gases are a mix of methane and hydrogen, the researchers get a microcrystalline diamond film made up of many tiny diamond crystals that average about 800 nanometers in size. If nitrogen is added to that gas mixture, the researchers get nanostructured diamond, made up of extremely tiny diamond crystals averaging just 60 nanometers in size.

In the present study, the Vohra team added boron, in the form of diborane, or B2H6, to the hydrogen/methane/nitrogen feed gas and found surprising results. The grain size in the diamond film abruptly increased from the 60-nanometer, nanostructured size seen with the hydrogen/methane/nitrogen feed gas to an 800-nanometer, microcrystalline size. Furthermore, this change occurred with just minute amounts of diborane, only 170 parts per million in the plasma.

Using optical emission spectroscopy and varying the amounts of diborane in the feed gas, Vohra’s group found that the diborane decreases the amounts of carbon-nitrogen radicals in the plasma. Thus, Vohra said, “our study has clearly identified the role of carbon-nitrogen species in the synthesis of nanostructured diamond and suppression of carbon-nitrogen species by addition of boron to the plasma.”

Since the addition of boron can also change the diamond film from a nonconductor into a semiconductor, the UAB results offer a new control of both diamond film grain size and electrical properties for various applications.

Over the next several years, Vohra and colleagues will probe the use of the microwave plasma chemical vapor deposition process to make thin films of boron carbides, boron nitrides and carbon-boron-nitrogen compounds, looking for compounds that survive heat better than diamonds and also have a diamond-like hardness. In the presence of oxygen, diamonds start to burn at about 1,100 degrees Fahrenheit.