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Last year at Arm TechCon, SoftBank Chairman and President Masayoshi Son laid out an ambitious vision of a trillion connected devices. It’s a vision ARM is aggressively pursuing by working with their ecosystem to invisibly enable those trillion devices to connect securely.

Connecting a trillion devices is no easy task of course but doing it securely is key. Especially when the tools and techniques used by attackers are rapidly evolving to go after every piece of system hardware from foundational SoCs to peripheral components. All are seen as an opportunity to access privileged data. With daily occurrences of cyber-attacks, it’s clear security across the entire device needs to be considered at the design stage, not as an afterthought.

At the SoC level, there are many classes of threats including those where attackers try to take advantage of the physical characteristics of the silicon implementation manifested during algorithmic execution. Today, ARM is announcing the availability of highly-efficient on-die threat mitigation technology designed to protect against threats including:

  • Simple and Differential Power Analysis (SPA/DPA), where an attacker is trying to compromise confidential information (e.g. a secret cryptographic key) through various analysis methods of the power consumed by an integrated circuit (IC) during operation
  • Simple and Differential Electromagnetic Analysis (SEMA/DEMA), where an attacker is trying to compromise confidential information (e.g. a secret cryptographic key) through various analysis methods of the electromagnetic field created during IC operation

The power and electromagnetic analysis mitigation technology relieves designers of the need to worry about this category of non-invasive attacks, while providing a solution that is easily scalable to cover changes in the protected logic. The resulting system benefit is addressing the leakage source directly and preventing sensitive data leakage through the IC power consumption and electromagnetic emission. From an implementation perspective, the mitigation technology is applicable across the full spectrum of silicon processes used in the semiconductor industry.

Trust between connected devices and their users is a critical factor in the continued growth of the IoT, particularly in applications making use of highly sensitive data, such as autonomous vehicles, mobile payment systems and connected health. Adding this technology to our security IP portfolio will enable the deployment of more secure devices as we drive toward our vision of a truly connected world.

To learn more about ARM security solutions, attend the security track at Arm TechCon, (Oct. 24-26 in Santa Clara, CA.)

Scientists at the University of Sussex may have found a solution to the long-standing problem of brittle smart phone screens.

Professor Alan Dalton and his team have developed a new way to make smart phone touch screens that are cheaper, less brittle, and more environmentally friendly. On top of that, the new approach also promises devices that use less energy, are more responsive, and do not tarnish in the air.

Dr. Matthew Large, University of Sussex, flexes a screen made from acrylic plastic coated in silver nanowires and grapheme to illustrate the kind of touch screens that can potentially be produced using the new approach Credit: Dr. Matthew Large

Dr. Matthew Large, University of Sussex, flexes a screen made from acrylic plastic coated in silver nanowires and grapheme to illustrate the kind of touch screens that can potentially be produced using the new approach Credit: Dr. Matthew Large

The problem has been that indium tin oxide, which is currently used to make smart phone screens, is brittle and expensive. The primary constituent, indium, is also a rare metal and is ecologically damaging to extract. Silver, which has been shown to be the best alternative to indium tin oxide, is also expensive. The breakthrough from physicists at the University of Sussex has been to combine silver nanowires with graphene – a two dimensional carbon material. The new hybrid material matches the performance of the existing technologies at a fraction of the cost.

In particular, the way in which these materials are assembled is new. Graphene is a single layer of atoms, and can float on water. By creating a stamp – a bit like a potato stamp a child might make – the scientists can pick up the layer of atoms and lay it on top of the silver nanowire film in a pattern. The stamp itself is made from poly(dimethyl siloxane); the same kind of silicone rubber used in kitchen utensils and medical implants.

Professor Alan Dalton from the school of Maths and Physical Science at the University of Sussex, says:

“While silver nanowires have been used in touch screens before, no one has tried to combine them with graphene. What’s exciting about what we’re doing is the way we put the graphene layer down. We float the graphene particles on the surface of water, then pick them up with a rubber stamp, a bit like a potato stamp, and lay it on top of the silver nanowire film in whatever pattern we like. “And this breakthrough technique is inherently scalable. It would be relatively simple to combine silver nanowires and graphene in this way on a large scale using spraying machines and patterned rollers. This means that brittle mobile phone screens might soon be a thing of the past.

“The addition of graphene to the silver nanowire network also increases its ability to conduct electricity by around a factor of ten thousand. This means we can use a fraction of the amount of silver to get the same, or better, performance. As a result screens will be more responsive and use less power.”

Dr Matthew Large, lead researcher on the project within the school of Maths and Physical Science at the University of Sussex, says:

“Although silver is also a rare metal, like indium, the amount we need to coat a given area is very small when combined with graphene. Since graphene is produced from natural graphite – which is relatively abundant – the cost for making a touch sensor drops dramatically.

“One of the issues with using silver is that it tarnishes in air. What we’ve found is that the graphene layer prevents this from happening by stopping contaminants in the air from attacking the silver. “What we’ve also seen is that when we bend the hybrid films repeatedly the electrical properties don’t change, whereas you see a drift in the films without graphene that people have developed previously. This paves the way towards one day developing completely flexible devices.”

Piezoelectric materials are used for applications ranging from the spark igniter in barbeque grills to the transducers needed by medical ultrasound imaging. Thin-film piezoelectrics, with dimensions on the scale of micrometers or smaller, offer potential for new applications where smaller dimensions or a lower voltage operation are required.

Researchers at Pennsylvania State University have demonstrated a new technique for making piezoelectric microelectromechanical systems (MEMS) by connecting a sample of lead zirconate titanate (PZT) piezoelectric thin films to flexible polymer substrates. Doctoral candidate Tianning Liu and her co-authors report their results this week in the Journal of Applied Physics, from AIP Publishing.

Electroded thin-film PZT on a flexible polyimide substrate of relatively large area. Credit: Tianning Liu

Electroded thin-film PZT on a flexible polyimide substrate of relatively large area. Credit: Tianning Liu

“There’s a rich history of work on piezoelectric thin films, but films on rigid substrates have limitations that come from the substrate,” said Thomas N. Jackson, a professor at Penn State and one of the paper’s authors. “This work opens up new areas for thin-film piezoelectrics that reduce the dependence on the substrate.”

The researchers grew polycrystalline PZT thin films on a silicon substrate with a zinc oxide release layer, to which they added a thin layer of polyimide. They then used acetic acid to etch away the zinc oxide, releasing the 1-micrometer thick PZT film with the polyimide layer from the silicon substrate. The PZT film on polyimide is flexible while possessing enhanced material properties compared to the films grown on rigid substrates.

Piezoelectric devices rely on the ability of some substances like PZT to generate electric charges when physically deformed, or inversely to deform when an electric field is applied to them. Growing high-quality PZT films, however, typically requires temperatures in excess of 650 degrees Celsius, almost 300 degrees hotter than what polyimide is able to withstand without degrading.

Most current piezoelectric device applications use bulk materials, which hampers miniaturization, precludes significant flexibility, and necessitates high-voltage operation.

“For example, if you’re looking at putting an ultrasound transducer in a catheter, a PZT film on a polymer substrate would allow you to wrap the transducer around the circumference of the catheter,” Liu said. “This could allow for significant miniaturization, and should provide more information for the clinician.”

The performance of many piezoelectric thin films has been limited by substrate clamping, a phenomenon in which the rigid substrate constrains the movement of the piezoelectric material’s domain walls and degrades its properties. Some work has been done crystallizing PZT at temperatures that are compatible with polymeric materials, for example using laser crystallization, but results thus far have led to porous thin films and inferior material properties.

The released thin films on polyimide that the researchers developed had a 45 percent increase in remanent polarization over silicon substrate controls, indicating a substantial mitigation in substrate clamping and improved performance. Even then, Liu said, much work remains before thin-film MEMS devices can compete with bulk piezoelectric systems.

“There’s still a big gap between putting PZT on thin film and bulk,” she said. “It’s not as big as between bulk and substrate, but there are also things like more defects that contribute to the lower response of the thin-film materials.”

STMicroelectronics (NYSE: STM) has taken underwater accuracy to new heights with its latest miniature pressure sensor, which is featured in the new Samsung Gear Fit 2 Pro.

As smart watches and wearable fitness trackers permeate the fabric of everyday life, owners want to go further with their devices and track performance across extra activities like swimming. Samsung’s Gear Fit 2 Pro, the next generation of sports band, supports these trends with features like built-in GPS, continuous heart rate monitoring, and larger on-board memory to do more even when not connected to a smartphone. ST’s new waterproof pressure sensor, the LPS33HW, is part of the mix: resistant to chemicals like chlorine, bromine, and salt water, it is ideal for pool or sea swimming, and will also resist soaps or detergents used when showering or cleaning.

Wearables are only just beginning to swim, and waterproofing pressure sensors creates challenges beyond just protecting the electronics. The LPS33HW is not only the most accurate, but also helps OEMs get their products to the store-shelves more quickly by recovering sooner after the stresses of manufacturing. Other sensors can require up to seven days to regain maximum accuracy after coming off the production line, but devices containing the LPS33HW are ready for action in less than half that time. This is due to the sensor’s high-performance built-in processor and the advanced formula of its water-resistant gel filling.

“Wearable trackers enhance smart living, and can now deliver an important extra boost with the go-anywhere ruggedness aided by our water-resistant LPS33HW sensor,” said Andrea Onetti, MEMS Sensor Division General Manager, STMicroelectronics. “Samsung takes advantage of the pressure sensor’s best-in-class performance for the new Gear Fit 2 Pro range and users will appreciate both its accuracy and toughness.”

In addition to smart consumer devices like wearables, other equipment including industrial sensors and utility meters can also benefit from the robustness and high measurement accuracy of the LPS33HW. The 10bar pressure sensor can withstand being submerged up to 90 meters, and the very low RMS pressure noise of 0.008mbar allows apps like an altimeter, depth gauge, or weather monitor to deliver consistent and stable results. The sensor accuracy drifts by less than ±1mbar per year.

When soldered to a circuit board during product manufacture, the accuracy is affected by less than ±2mbar, and returns to normal after less than 72 hours – significantly quicker than similar water-resistant pressure sensors.

The LPS33HW is in production now, in a 3.3mm x 3.3mm x 2.9mm cylindrical metal package suitable for use with O-ring seals, priced from $4.50 for orders of 1000 pieces.

Seoul Semiconductor, a developer of LED products and technology recently introduced its Horticultural Series LEDs in COB, mid-power, and high-power packages, making Seoul the only LED manufacturer to provide lighting designers with the complete spectrum of light used for growing plants – spanning the spectrum from ultraviolet (UV-C) to far-red. The new product family also includes Seoul’s SunLike Series natural spectrum LEDs, which produce light that closely matches the spectrum of natural sunlight.

Seoul Semiconductor introduced the new Horticultural Series LEDs at the 2017 Horticultural Lighting Conference in Denver, CO, on October 17. One of the invited speakers for the conference will be Dr. Peter Barber, product marketing manager for Seoul VioSys, on “The Myriad Ways That UV LEDs Will Impact Society Through Horticultural Lighting.”

Delivering a full spectrum of possibilities for horticultural applications
While many conventional LED manufacturers have developed horticultural-optimized LEDs in the visible light spectrum from violet (~390nm) to red (~700nm) wavelengths, the new Horticultural Series LEDs from Seoul Semiconductor extend this spectrum to include multiple ultraviolet bands (UV-A, UV-B & UV-C), as well as into far-red bands (~700nm to 800nm). The extension of this new LED product series beyond the ends of the visible spectrum provides horticultural lighting designers with the capability to develop the widest range of light sources beneficial for growing and propagating different types of vegetables and plants in indoor settings.

Also playing a critical role in the new Horticultural Series LED family is Seoul Semiconductor’s recently-introduced SunLike LED technology, the first LED to closely match the spectrum of natural sunlight, providing a light source more like natural light than conventional “white light” LEDs, providing lighting designers with a wider range of options as they develop horticultural-specific lighting systems.

“By extending the spectrum of LEDs to include both ultraviolet and far-red light sources, Seoul Semiconductor provides horticultural lighting designers an entirely new spectrum of possibilities in developing lighting systems for specific plant growth and propagation,” explained Mark McClear, Vice President, Americas, of Seoul Semiconductor. “Our Horticultural Series LEDs include high-power, mid-power and COB devices, enabling the design of a wide range of lighting fixtures – from high-bay and directional lights to rack-mounted fixtures for vertical farming systems – all from a single LED manufacturer.”

SunLike Series Chip-on-Board (COB) LEDs
For lighting fixtures designed to produce light that closely matches the spectrum of natural sunlight, Seoul offers a range of standard COB LED modules ranging from 6W to 25W.

High Power Horticultural Series LEDs include UV, white, and color devices
For high-bay and other lighting fixtures, Seoul’s Horticultural Series LEDs include the following options:
Ultraviolet
UV-C – Producing dominant wavelength of 275nm, these un-lensed UV LEDs can be used for sterilization.
UV-B – Producing dominant wavelength between 280 – 310nm, these un-lensed UV LEDs are rated at 10mW with a photosynthetic photon flux (PPF) value of 0.25µmols/s.
UV-A – Producing dominant wavelength between 360 – 400nm, these lensed UV LEDs are rated at 636mW with a PPF value of 2.2µmols/s.
Deep Blue – Featuring a dominant wavelength of 449 – 461nm, these deep blue dome-lensed LEDs are rated at 650mW with a PPF of 2.6µmols/s.
Deep Red – With a dominant wavelength of 646 – 665nm, these visible red LEDs are rated at 345mW with a PPF of 2.32µmols/s.
Far-Red – Producing a dominant wavelength of ~730nm (peak), these near-infrared LEDs are rated at 260mW with a PPF of 1.64µmols/s.
White – These high-power white LEDs feature a light output of 168lm with a PPF of 2.4µmols/s.

Mid Power Horticultural Series LEDs include SunLike natural spectrum LEDs & color devices
For vertical rack systems and other close-up lighting fixtures, Seoul’s Horticultural Series LEDs include the following mid-power options in standard 3030 packages:
SunLike 5000K – With a color temperature ranging from 2700K – 5000K, these LEDs produce light that closely matches the spectrum of natural sunlight, and feature a light output of 22.3lm with a PPF of 0.38µmols/s.
Deep Blue – Featuring a dominant wavelength of 449 – 461nm, these blue mid-power LEDs are rated at 155mW with a PPF of 0.62µmols/s.
Deep-Red – With a dominant wavelength of 646 – 665nm, these visible red LEDs have a PPF of 0.43µmols/s, and a light output of 77lm/mW.
Far-Red – Producing a dominant wavelength of ~730nm (peak), these near-infrared mid-power LEDs are rated at 50mW with a PPF of 0.38µmols/s.

Fibers made of carbon nanotubes configured as wireless antennas can be as good as copper antennas but 20 times lighter, according to Rice University researchers. The antennas may offer practical advantages for aerospace applications and wearable electronics where weight and flexibility are factors.

The research appears in Applied Physics Letters.

The discovery offers more potential applications for the strong, lightweight nanotube fibers developed by the Rice lab of chemist and chemical engineer Matteo Pasquali. The lab introduced the first practical method for making high-conductivity carbon nanotube fibers in 2013 and has since tested them for use as brain implants and in heart surgeries, among other applications.

The research could help engineers who seek to streamline materials for airplanes and spacecraft where weight equals cost. Increased interest in wearables like wrist-worn health monitors and clothing with embedded electronics could benefit from strong, flexible and conductive fiber antennas that send and receive signals, Pasquali said.

The Rice team and colleagues at the National Institute of Standards and Technology (NIST) developed a metric they called “specific radiation efficiency” to judge how well nanotube fibers radiated signals at the common wireless communication frequencies of 1 and 2.4 gigahertz and compared their results with standard copper antennas. They made thread comprising from eight to 128 fibers that are about as thin as a human hair and cut to the same length to test on a custom rig that made straightforward comparisons with copper practical.

“Antennas typically have a specific shape, and you have to design them very carefully,” said Rice graduate student Amram Bengio, the paper’s lead author. “Once they’re in that shape, you want them to stay that way. So one of the first experimental challenges was getting our flexible material to stay put.”

Contrary to earlier results by other labs (which used different carbon nanotube fiber sources), the Rice researchers found the fiber antennas matched copper for radiation efficiency at the same frequencies and diameters. Their results support theories that predicted the performance of nanotube antennas would scale with the density and conductivity of the fiber.

“Not only did we find that we got the same performance as copper for the same diameter and cross-sectional area, but once we took the weight into account, we found we’re basically doing this for 1/20th the weight of copper wire,” Bengio said.

“Applications for this material are a big selling point, but from a scientific perspective, at these frequencies carbon nanotube macro-materials behave like a typical conductor,” he said. Even fibers considered “moderately conductive” showed superior performance, he said. Although manufacturers could simply use thinner copper wires instead of the 30-gauge wires they currently use, those wires would be very fragile and difficult to handle, Pasquali said.

“Amram showed that if you do three things right — make the right fibers, fabricate the antenna correctly and design the antenna according to telecommunication protocols — then you get antennas that work fine,” he said. “As you go to very thin antennas at high frequencies, you get less of a disadvantage compared with copper because copper becomes difficult to handle at thin gauges, whereas nanotubes, with their textile-like behavior, hold up pretty well.”

The huge increase in computing performance in recent decades has been achieved by squeezing ever more transistors into a tighter space on microchips.

However, this downsizing has also meant packing the wiring within microprocessors ever more tightly together, leading to effects such as signal leakage between components, which can slow down communication between different parts of the chip. This delay, known as the “interconnect bottleneck,” is becoming an increasing problem in high-speed computing systems.

One way to tackle the interconnect bottleneck is to use light rather than wires to communicate between different parts of a microchip. This is no easy task, however, as silicon, the material used to build chips, does not emit light easily, according to Pablo Jarillo-Herrero, an associate professor of physics at MIT.

Now, in a paper published today in the journal Nature Nanotechnology, researchers describe a light emitter and detector that can be integrated into silicon CMOS chips. The paper’s first author is MIT postdoc Ya-Qing Bie, who is joined by Jarillo-Herrero and an interdisciplinary team including Dirk Englund, an associate professor of electrical engineering and computer science at MIT.

The device is built from a semiconductor material called molybdenum ditelluride. This ultrathin semiconductor belongs to an emerging group of materials known as two-dimensional transition-metal dichalcogenides.

Unlike conventional semiconductors, the material can be stacked on top of silicon wafers, Jarillo-Herrero says.

“Researchers have been trying to find materials that are compatible with silicon, in order to bring optoelectronics and optical communication on-chip, but so far this has proven very difficult,” Jarillo-Herrero says. “For example, gallium arsenide is very good for optics, but it cannot be grown on silicon very easily because the two semiconductors are incompatible.”

In contrast, the 2-D molybdenum ditelluride can be mechanically attached to any material, Jarillo-Herrero says.

Another difficulty with integrating other semiconductors with silicon is that the materials typically emit light in the visible range, but light at these wavelengths is simply absorbed by silicon.

Molybdenum ditelluride emits light in the infrared range, which is not absorbed by silicon, meaning it can be used for on-chip communication.

To use the material as a light emitter, the researchers first had to convert it into a P-N junction diode, a device in which one side, the P side, is positively charged, while the other, N side, is negatively charged.

In conventional semiconductors, this is typically done by introducing chemical impurities into the material. With the new class of 2-D materials, however, it can be done by simply applying a voltage across metallic gate electrodes placed side-by-side on top of the material.

“That is a significant breakthrough, because it means we do not need to introduce chemical impurities into the material [to create the diode]. We can do it electrically,” Jarillo-Herrero says.

Once the diode is produced, the researchers run a current through the device, causing it to emit light.

“So by using diodes made of molybdenum ditelluride, we are able to fabricate light-emitting diodes (LEDs) compatible with silicon chips,” Jarillo-Herrero says.

The device can also be switched to operate as a photodetector, by reversing the polarity of the voltage applied to the device. This causes it to stop conducting electricity until a light shines on it, when the current restarts.

In this way, the devices are able to both transmit and receive optical signals.

The device is a proof of concept, and a great deal of work still needs to be done before the technology can be developed into a commercial product, Jarillo-Herrero says.

The researchers are now investigating other materials that could be used for on-chip optical communication.

Most telecommunication systems, for example, operate using light with a wavelength of 1.3 or 1.5 micrometers, Jarillo-Herrero says.

However, molybdenum ditelluride emits light at 1.1 micrometers. This makes it suitable for use in the silicon chips found in computers, but unsuitable for telecommunications systems.

“It would be highly desirable if we could develop a similar material, which could emit and detect light at 1.3 or 1.5 micrometers in wavelength, where telecommunication through optical fiber operates,” he says.

To this end, the researchers are exploring another ultrathin material called black phosphorus, which can be tuned to emit light at different wavelengths by altering the number of layers used. They hope to develop devices with the necessary number of layers to allow them to emit light at the two wavelengths while remaining compatible with silicon.

“The hope is that if we are able to communicate on-chip via optical signals instead of electronic signals, we will be able to do so more quickly, and while consuming less power,” Jarillo-Herrero says.

Graphene – a one-atom-thick layer of the stuff in pencils – is a better conductor than copper and is very promising for electronic devices, but with one catch: Electrons that move through it can’t be stopped.

Until now, that is. Scientists at Rutgers University-New Brunswick have learned how to tame the unruly electrons in graphene, paving the way for the ultra-fast transport of electrons with low loss of energy in novel systems. Their study was published online in Nature Nanotechnology.

“This shows we can electrically control the electrons in graphene,” said Eva Y. Andrei, Board of Governors professor in Rutgers’ Department of Physics and Astronomy in the School of Arts and Sciences and the study’s senior author. “In the past, we couldn’t do it. This is the reason people thought that one could not make devices like transistors that require switching with graphene, because their electrons run wild.”

Now it may become possible to realize a graphene nano-scale transistor, Andrei said. Thus far, graphene electronics components include ultra-fast amplifiers, supercapacitors and ultra-low resistivity wires. The addition of a graphene transistor would be an important step towards an all-graphene electronics platform. Other graphene-based applications include ultra-sensitive chemical and biological sensors, filters for desalination and water purification. Graphene is also being developed in flat flexible screens, and paintable and printable electronic circuits.

Graphene is a nano-thin layer of the carbon-based graphite that pencils write with. It is far stronger than steel and a great conductor. But when electrons move through it, they do so in straight lines and their high velocity does not change. “If they hit a barrier, they can’t turn back, so they have to go through it,” Andrei said. “People have been looking at how to control or tame these electrons.”

Her team managed to tame these wild electrons by sending voltage through a high-tech microscope with an extremely sharp tip, also the size of one atom. They created what resembles an optical system by sending voltage through a scanning tunneling microscope, which offers 3-D views of surfaces at the atomic scale. The microscope’s sharp tip creates a force field that traps electrons in graphene or modifies their trajectories, similar to the effect a lens has on light rays. Electrons can easily be trapped and released, providing an efficient on-off switching mechanism, according to Andrei.

“You can trap electrons without making holes in the graphene,” she said. “If you change the voltage, you can release the electrons. So you can catch them and let them go at will.”

The next step would be to scale up by putting extremely thin wires, called nanowires, on top of graphene and controlling the electrons with voltages, she said.

An interdisciplinary team of scientists at the U.S. Naval Research Laboratory (NRL) has uncovered a direct link between sample quality and the degree of valley polarization in monolayer transition metal dichalcogenides (TMDs). In contrast with graphene, many monolayer TMDs are semiconductors and show promise for future applications in electronic and optoelectronic technologies.

In this sense, a ‘valley’ refers to the region in an electronic band structure where both electrons and holes are localized, and ‘valley polarization’ refers to the ratio of valley populations — an important metric applied in valleytronics research.

Upper Panel: schematic of optical excitation in the K valley of WS2 monolayers. Lower Panel: Photoluminescence (PL) intensity map of a triangular monolayer island of WS2 and the associated valley polarization map demonstrate the clear inverse relationship. Each map covers a 46 x 43 micron area. The regions exhibiting smallest PL intensity and lowest quality are found at the center of the flake and radiate outward toward the three corners. These regions correspond to the highest valley polarization. Credit: US Naval Research Laboratory

Upper Panel: schematic of optical excitation in the K valley of WS2 monolayers. Lower Panel: Photoluminescence (PL) intensity map of a triangular monolayer island of WS2 and the associated valley polarization map demonstrate the clear inverse relationship. Each map covers a 46 x 43 micron area. The regions exhibiting smallest PL intensity and lowest quality are found at the center of the flake and radiate outward toward the three corners. These regions correspond to the highest valley polarization. Credit: US Naval Research Laboratory

“A high degree of valley polarization has been theoretically predicted in TMDs yet experimental values are often low and vary widely,” said Kathleen McCreary, Ph.D., lead author of the study. “It is extremely important to determine the origin of these variations in order to further our basic understanding of TMDs as well as advance the field of valleytronics.”

Many of today’s technologies (i.e. solid state lighting, transistors in computer chips, and batteries in cell phones) rely simply on the charge of the electron and how it moves through the material. However, in certain materials such as the monolayer TMDs, electrons can be selectively placed into a chosen electronic valley using optical excitation.

“The development of TMD materials and hybrid 2D/3D heterostructures promises enhanced functionality relevant to future Department of Defense missions,” said Berend Jonker, Ph.D., principal investigator of the program. “These include ultra-low power electronics, non-volatile optical memory, and quantum computation applications in information processing and sensing.”

The growing fields of spintronics and valleytronics aim to use the spin or valley population, rather than only charge, to store information and perform logic operations. Progress in these developing fields has attracted the attention of industry leaders, and has already resulted in products such as magnetic random access memory that improve upon the existing charge-based technologies.

The team focused on TMD monolayers such as WS2 and WSe2, which have high optical responsivity, and found that samples exhibiting low photoluminescence (PL) intensity exhibited a high degree of valley polarization. These findings suggest a means to engineer valley polarization via controlled introduction of defects and nonradiative recombination sites

“Truly understanding the reason for sample-to-sample variation is the first step towards valleytronic control,” McCreary said. “In the near future, we may be able to accurately increase polarization by adding defect sites or reduce polarization by passivation of defects.”

Results of this research are reported in the August 2017 edition of the American Chemical Society’s Nano, The research team is comprised of Dr. Kathleen McCreary, Dr. Aubrey Hanbicki, and Dr. Berend Jonker from the NRL Materials Science and Technology Division; Dr. Marc Currie from the NRL Optical Sciences Division; and Dr. Hsun-Jen Chuang who holds an American Society for Engineering Education (ASEE) fellowship at NRL.

Leti, a research institute of CEA Tech, today announced a new European Horizon 2020 project to develop innovative electric drivetrains for third-generation electric vehicles.

Bringing together 10 European research institutes, key members of the automotive-industry value chain and universities, the ModulED project will focus on boosting drivetrain performance to meet vehicle-owner requirements, making manufacturing more efficient and reducing environmental impact and vehicle cost. The project team will leverage recent innovations from diverse industries. These include integrating the frequency, voltage and high-temperature benefits of wide-bandgap semiconductors fabricated with gallium nitride. These devices allow the electronic circuitry that changes direct current to alternating current (DC-AC) to be integrated directly into the motor.

Other recent innovations the project will develop for the new drivetrains include:

  • Processes for manufacturing magnetic materials for the magnetic part of the motor, lowering the density of the rare-earth element
  • Motor architecture that allows modularity in production
  • Transmission and cooling systems that are compatible with hybrid vehicles
  • Optimization of braking systems to recover energy in the braking phase.

“Electric vehicles are a key component of the EU’s commitment to limit climate change, but current electric vehicles face challenges preventing large market acceptance, including consumer resistance due to cost and limited driving ranges,” said Bernard Strée, project coordinator at Leti. “ModulED will target these challenges via the manufacturing process, including the mass-production context, increased value-chain involvement and lifecycle analysis for optimized duration and minimized environmental impact.”

Coordinated by Leti, the three-year, €7.2 million project includes the companies BRUSA Elektronik AG (Switzerland), Punch Powertrain NV (Belgium), ZG GmbH (Germany), Siemens (France), Efficient Innovation (France); universities RTWH Aachen University, Chalmers University and Eindhoven University of Technology, and Leti’s sister institute, Liten.

The ModulED project, which leverages Leti’s expertise in wide-bandgap semiconductors along with Liten’s knowhow in magnetic materials and simulation, launches this month in Grenoble.