Category Archives: Packaging Materials

Full(erene) potential


February 3, 2017

In what could be called a classic “Eureka” moment, UC Santa Barbara materials researchers have discovered a simple yet effective method for mastering the electrical properties of polymer semiconductors. The elegant technique allows for the efficient design and manufacture of organic circuitry (the type found in flexible displays and solar cells, for instance) of varying complexity while using the same semiconductor material throughout.

“It’s a different strategy by which you can take a material and change its properties,” said Guillermo Bazan, a professor of chemistry and materials at UCSB. With the addition of fullerene or copper tetrabenzoporphyrin (CuBP) molecules in strategic places, the charge carriers in semiconducting materials — negative electrons and positive “holes” — may be controlled and inverted for better device performance as well as economical manufacture. The discovery is published in a pair of papers that appear in the journals Advanced Functional Materials and Advanced Electronic Materials.

In the realm of polymer semiconductors, device functionality depends on the movement of the appropriate charge carriers across the material. There have been many advances in the synthesis of high-mobility, high-performance materials, said lead author Michael Ford, graduate student in materials, but the fine control of the electrons and holes is what will allow these sophisticated polymers to reach their full potential.

“There’s been a large effort to make new materials, but a lot of them may not be appropriate in conventional low-power devices,” said Ford. Many of these materials exhibit “ambipolar” conduction, meaning that they transport both negative and positive charges, he explained. So, in situations where only a certain charge is required, the opposite charge is also conducting, which diminishes the utility of the material.

“They’re always ‘on’ so you always have a current running through the device,” Ford said. Conventional means of controlling the movement of charge carriers often involves more complex measures, such as multiple metal evaporation steps or depositing additional layers that are difficult to manage. These actions often require more complicated processing or fabrication, which could in the end defeat the purpose of low-cost flexible electronics.

This new development was actually a classic accidental scientific discovery, according to Ford, who was investigating, simultaneously, the properties of two materials. He observed that the use of fullerene additives limited conduction of one charge carrier (negative electrons), while allowing the other (positive holes) to remain mobile.

“In one experiment, we were just trying to do some extra measurements for a poster, and while making a measurement I noticed it solved the problem that I was having with my other material, which was this problem of never turning off,” Ford said. He decided to employ the fullerene additive from one experiment to address issues in the other and found it could be used to allow only positive charges to move, while adding operational stability.

From there, he and his collaborators worked to control negative charge conduction in the same way. A different additive — one that “likes” holes, CuBP — was introduced and turned off ambipolar transport in the opposite way from the fullerene. Now negative electrons remain mobile and hole transport is limited.

“We had two devices, both using the same polymer semiconductor but with different additives,” Ford explained. “One was a switch for holes, and the other was a switch for electrons. This enabled us to develop a complementary inverter, which is just like the building blocks that make up circuits in modern cell phones and computers.”

“So we have for the first time this ability to take these ambipolar semiconductors and design through solution processing a circuit where in certain parts only the electrons are moving, or only the holes are moving,” Bazan said, “but keep the same semiconductor material.” The additives create “traps” that can be used to master the properties of the semiconductor in a straightforward way, he added.

The potential uses of this method are many, particularly in situations where low-cost, low-power flexible electronics would be helpful, such as printable packaging labels that function as temperature sensors for foods and other sensitive items being shipped long distances.

“It’s this idea where we can have an additive that can be a small fraction of the total and which will allow us to master the electronic properties of the semiconductor,” said Bazan. “Once you have that under control, you can do all sorts of cool things.”

Most batteries are composed of two solid, electrochemically active layers called electrodes, separated by a polymer membrane infused with a liquid or gel electrolyte. But recent research has explored the possibility of all-solid-state batteries, in which the liquid (and potentially flammable) electrolyte would be replaced by a solid electrolyte, which could enhance the batteries’ energy density and safety.

Now, for the first time, a team at MIT has probed the mechanical properties of a sulfide-based solid electrolyte material, to determine its mechanical performance when incorporated into batteries.

The new findings were published this week in the journal Advanced Energy Materials, in a paper by Frank McGrogan and Tushar Swamy, both MIT graduate students; Krystyn Van Vliet, the Michael (1949) and Sonja Koerner Professor of Materials Science and Engineering; Yet-Ming Chiang, a professor of materials science and engineering; and four others including an undergraduate participant in the National Science Foundation Research Experience for Undergraduate (REU) program administered by MIT’s Center for Materials Science and Engineering and its Materials Processing Center.

Lithium-ion batteries have provided a lightweight energy-storage solution that has enabled many of today’s high-tech devices, from smartphones to electric cars. But substituting the conventional liquid electrolyte with a solid electrolyte in such batteries could have significant advantages. Such all-solid-state lithium-ion batteries could provide even greater energy storage ability, pound for pound, at the battery pack level. They may also virtually eliminate the risk of tiny, fingerlike metallic projections called dendrites that can grow through the electrolyte layer and lead to short-circuits.

“Batteries with components that are all solid are attractive options for performance and safety, but several challenges remain,” Van Vliet says. In the lithium-ion batteries that dominate the market today, lithium ions pass through a liquid electrolyte to get from one electrode to the other while the battery is being charged, and then flow through in the opposite direction as it is being used. These batteries are very efficient, but “the liquid electrolytes tend to be chemically unstable, and can even be flammable,” she says. “So if the electrolyte was solid, it could be safer, as well as smaller and lighter.”

But the big question regarding the use of such all-solid batteries is what kinds of mechanical stresses might occur within the electrolyte material as the electrodes charge and discharge repeatedly. This cycling causes the electrodes to swell and contract as the lithium ions pass in and out of their crystal structure. In a stiff electrolyte, those dimensional changes can lead to high stresses. If the electrolyte is also brittle, that constant changing of dimensions can lead to cracks that rapidly degrade battery performance, and could even provide channels for damaging dendrites to form, as they do in liquid-electrolyte batteries. But if the material is resistant to fracture, those stresses could be accommodated without rapid cracking.

Until now, though, the sulfide’s extreme sensitivity to normal lab air has posed a challenge to measuring mechanical properties including its fracture toughness. To circumvent this problem, members of the research team conducted the mechanical testing in a bath of mineral oil, protecting the sample from any chemical interactions with air or moisture. Using that technique, they were able to obtain detailed measurements of the mechanical properties of the lithium-conducting sulfide, which is considered a promising candidate for electrolytes in all-solid-state batteries.

“There are a lot of different candidates for solid electrolytes out there,” McGrogan says. Other groups have studied the mechanical properties of lithium-ion conducting oxides, but there had been little work so far on sulfides, even though those are especially promising because of their ability to conduct lithium ions easily and quickly.

Previous researchers used acoustic measurement techniques, passing sound waves through the material to probe its mechanical behavior, but that method does not quantify the resistance to fracture. But the new study, which used a fine-tipped probe to poke into the material and monitor its responses, gives a more complete picture of the important properties, including hardness, fracture toughness, and Young’s modulus (a measure of a material’s capacity to stretch reversibly under an applied stress).

“Research groups have measured the elastic properties of the sulfide-based solid electrolytes, but not fracture properties,” Van Vliet says. The latter are crucial for predicting whether the material might crack or shatter when used in a battery application.

The researchers found that the material has a combination of properties somewhat similar to silly putty or salt water taffy: When subjected to stress, it can deform easily, but at sufficiently high stress it can crack like a brittle piece of glass.

By knowing those properties in detail, “you can calculate how much stress the material can tolerate before it fractures,” and design battery systems with that information in mind, Van Vliet says.

The material turns out to be more brittle than would be ideal for battery use, but as long as its properties are known and systems designed accordingly, it could still have potential for such uses, McGrogan says. “You have to design around that knowledge.”

Transparent window coatings that keep buildings and cars cool on sunny days. Devices that could more than triple solar cell efficiencies. Thin, lightweight shields that block thermal detection. These are potential applications for a thin, flexible, light-absorbing material developed by engineers at the University of California San Diego.

The material, called a near-perfect broadband absorber, absorbs more than 87 percent of near-infrared light (1,200 to 2,200 nanometer wavelengths), with 98 percent absorption at 1,550 nanometers, the wavelength for fiber optic communication. The material is capable of absorbing light from every angle. It also can theoretically be customized to absorb certain wavelengths of light while letting others pass through.

This is a near-perfect broadband absorber that's thin, flexible and transparent in visible light. Credit: UC San Diego Jacobs School of Engineering

This is a near-perfect broadband absorber that’s thin, flexible and transparent in visible light. Credit: UC San Diego Jacobs School of Engineering

Materials that “perfectly” absorb light already exist, but they are bulky and can break when bent. They also cannot be controlled to absorb only a selected range of wavelengths, which is a disadvantage for certain applications. Imagine if a window coating used for cooling not only blocked infrared radiation, but also normal light and radio waves that transmit television and radio programs.

By developing a novel nanoparticle-based design, a team led by professors Zhaowei Liu and Donald Sirbuly at the UC San Diego Jacobs School of Engineering has created a broadband absorber that’s thin, flexible and tunable. The work was published online on Jan. 24 in Proceedings of the National Academy of Sciences.

“This material offers broadband, yet selective absorption that could be tuned to distinct parts of the electromagnetic spectrum,” Liu said.

The absorber relies on optical phenomena known as surface plasmon resonances, which are collective movements of free electrons that occur on the surface of metal nanoparticles upon interaction with certain wavelengths of light. Metal nanoparticles can carry a lot of free electrons, so they exhibit strong surface plasmon resonance — but mainly in visible light, not in the infrared.

UC San Diego engineers reasoned that if they could change the number of free electron carriers, they could tune the material’s surface plasmon resonance to different wavelengths of light. “Make this number lower, and we can push the plasmon resonance to the infrared. Make the number higher, with more electrons, and we can push the plasmon resonance to the ultraviolet region,” Sirbuly said. The problem with this approach is that it is difficult to do in metals.

To address this challenge, engineers designed and built an absorber from materials that could be modified, or doped, to carry a different amount of free electrons: semiconductors. Researchers used a semiconductor called zinc oxide, which has a moderate number of free electrons, and combined it with its metallic version, aluminum-doped zinc oxide, which houses a high number of free electrons — not as much as an actual metal, but enough to give it plasmonic properties in the infrared.

The materials were combined and structured in a precise fashion using advanced nanofabrication technologies in the Nano3 cleanroom facility at the Qualcomm Institute at UC San Diego. The materials were deposited one atomic layer at a time on a silicon substrate to create an array of standing nanotubes, each made of alternating concentric rings of zinc oxide and aluminum-doped zinc oxide. The tubes are 1,730 nanometers tall, 650 to 770 nanometers in diameter, and spaced less than a hundred nanometers apart. The nanotube array was then transferred from the silicon substrate to a thin, elastic polymer. The result is a material that is thin, flexible and transparent in the visible.

“There are different parameters that we can alter in this design to tailor the material’s absorption band: the gap size between tubes, the ratio of the materials, the types of materials, and the electron carrier concentration. Our simulations show that this is possible,” said Conor Riley, a recent nanoengineering Ph.D. graduate from UC San Diego and the first author of this work. Riley is currently a postdoctoral researcher in Sirbuly’s group.

Those are just a few exciting features of this particle-based design, researchers said. It’s also potentially transferrable to any type of substrate and can be scaled up to make large surface area devices, like broadband absorbers for large windows. “Nanomaterials normally aren’t fabricated at scales larger than a couple centimeters, so this would be a big step in that direction,” Sirbuly said.

The technology is still at the developmental stage. Liu and Sirbuly’s teams are continuing to work together to explore different materials, geometries and designs to develop absorbers that work at different wavelengths of light for various applications.

FlexTech, a SEMI strategic association partner, today announced a contract with ITN Energy Systems of Littleton, CO to develop and produce a flexible, solid-state lithium battery reducing packaging bulk by integrating a thin, flexible ceramic substrate. The unique ceramic substrate material is produced by ENrG Inc. of Buffalo, NY and is technology licensed from Corning Incorporated. The project duration is 15 months with a total value of $1.5 million.

“This work will break new ground in flexible battery development and address the many challenges associated with this area,” notes Melissa Grupen-Shemansky, chief technology officer for FlexTech | SEMI.  “This technology is one of the most promising for multi-cell packages and infinitely-expandable battery components.”

“We look forward to working with FlexTech and the FlexTech Technical Council in developing this new approach to flexible power supplies which promises up to 10x the capacity with one-half the thickness of products currently in the market,” said Brian Berland, chief science officer for ITN Energy Systems. “Once completed, we believe that rapid market adoption of this product is highly likely, since power availability and management is a significant bottleneck to many innovative FHE products.”

This type of battery is widely sought by developers of flexible electronic printed devices, such as wearable and medical devices. Product goals include a size of no larger than 2″x 3″ x .01″ and up to a 500 mAh capacity.  This thin film approach to lithium batteries eliminates the liquid electrolytes which are part of the typical lithium-ion product, and has caused difficulties with heat dissipation and reliability of some products on the market. The benefits of placing these batteries on ceramic substrates include low water and oxygen transmission without adding packaging material, cost or thickness. An important part of the project is selecting a sealing material based on compatibility with the assembly process and the ultimate performance of the battery.

Each year, Solid State Technology turns to industry leaders to hear viewpoints on the technological and economic outlook for the upcoming year. Read through these expert opinions on what to expect in 2017.

Driving the industry forward with materials engineering

Raja_Prabu_fullPrabu Raja, vice president and general manager, Patterning and Packaging Group, Applied Materials, Inc.

Over the past few years, the industry has made remarkable progress in bringing 3D chip architectures to volume production. In 2017, we will continue to see exciting technology innovations for scaling 3D NAND devices to 64 layers, ramping the 10nm process node into volume manufacturing and increasing the adoption of highly integrated chip packages.

With the transition to the 3D and sub-10nm era, the semiconductor world is changing from lithography-based scaling to materials-enabled scaling. This shift requires multiple new materials and capabilities in selective processing.

The magnitude and pace of these changes are truly disruptive. For example, with 3D NAND materials innovations for hard mask deposition and hard mask etch are essential. The challenge is to build high aspect ratio vertical structures with uniform profiles from the top to the bottom as more layers are added. Selective removal processes can remove targeted materials in vertical and horizontal structures without damage or residue throughout the stack.

For logic/foundry, the introduction of the 10nm process node in volume manufacturing brings significant growth in the number of patterning steps. This trend will increase even more for 7nm and below designs. Patterning these advanced nodes requires innovative etch capabilities to deliver feature-scale uniformity with low line edge roughness. Selective processes and alternative manufacturing schemes will also be needed as the industry seeks solutions for layer-to-layer vertical alignment. We expect this to result in a two-fold increase in the number of materials to be deposited and removed.

Finally, the industry will continue to adopt new and improved packaging schemes for enabling increased device performance, lower power consumption and to deliver desired form factors. In 2016, we saw the volume adoption of Fan-Out packaging in mobile devices and this trend is expected to grow further in 2017. The high performance computing segment will pursue 2.5D interposer and/or 3D TSV packaging schemes for higher memory bandwidth, lower latency and better power efficiency.

Applied Materials is focused on delivering game-changing selective process technologies and materials innovations to help solve the industry’s toughest challenges.

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A team of researchers, affiliated with UNIST has recently announced that they have successfully developed a new way to increase energy efficiency of metal-air batteries which are next-generation energy devices by using a conducting polymer.

This breakthrough research, led by Professor Hyun-Kon Song and Professor Guntae Kim of Energy and Chemical Engineering is appeared in the January issue of Energy & Environmental Science (EES), a world renowned academic journal in the field of energy.

In the cathode of metal-air batteries or fuel cells, oxygen is reduced to metal oxide or water. At this time, catalysts are required to accelerate the reaction. As the well known catalyst, platinum has remaining economical issue to commercialize the metal-air betteries or fuel cell due to its high price.

In the study, they reported that catalytic activity of provskite which can be substitute to platinum was dramatically enhanced by simply adding a kind of conducting polymer, polypyrrole and its principle.

When the perovskite or polypyrrole are used alone, their activities can not be reached to that of platinum. However, as a result of physically mixing perovksite with polypyrrole, the activity was dramatically enhanced and it was reached to that of platinum. This is first synergistic effect in oxygen electrocatalysis even though there was any chemical interaction between pervskite and polypyrrole.

“The reaction which oxygen receive electron is oxygen reduction. The property of polypyrrole which is sensitive to oxygen contribute to accelerate this reaction,” says Professor Song.

“Because the oxide-polypyrrole complex is made by simple operation, the catalyst will be proper to apply next-generation energy devices,” says Dong-Gyu Lee, the first author of the research.

The results of this study has been supported by KEIT, KETEP, BK21Plus and MSIP.

A simple technique for producing oxide nanowires directly from bulk materials could dramatically lower the cost of producing the one-dimensional (1D) nanostructures. That could open the door for a broad range of uses in lightweight structural composites, advanced sensors, electronic devices – and thermally-stable and strong battery membranes able to withstand temperatures of more than 1,000 degrees Celsius.

The technique uses a solvent reaction with a bimetallic alloy – in which one of the metals is reactive – to form bundles of nanowires (nanofibers) upon reactive metal dissolution. The process is conducted at ambient temperature and pressure without the use of catalysts, toxic chemicals or costly processes such as chemical vapor deposition. The produced nanowires can be used to improve the electrical, thermal and mechanical properties of functional materials and composites.

The research, which is scheduled to be reported this week in the journal Science, was supported by the National Science Foundation and California-based Sila Nanotechnologies. The process is believed to be the first to convert bulk powders to nanowires at ambient conditions.

Researchers have developed a new low-cost technique for converting bulk powders directly to oxide nanowires. Shown is a crucible in which an alloy of lithium and aluminum is being formed. Credit: Rob Felt, Georgia Tech

Researchers have developed a new low-cost technique for converting bulk powders directly to oxide nanowires. Shown is a crucible in which an alloy of lithium and aluminum is being formed. Credit: Rob Felt, Georgia Tech

“This technique could open the door for a range of synthesis opportunities to produce low-cost 1D nanomaterials in large quantities,” said Gleb Yushin, a professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. “You can essentially put the bulk materials into a bucket, fill it with a suitable solvent and collect nanowires after a few hours, which is way simpler than how many of these structures are produced today.”

Yushin’s research team, which included former graduate students Danni Lei and James Benson, has produced oxide nanowires from lithium-magnesium and lithium-aluminum alloys using a variety of solvents, including simple alcohols. Production of nanowires from other materials is part of ongoing research that was not reported in the paper.

The dimensions of the nanowire structures can be controlled by varying the solvent and the processing conditions. The structures can be produced in diameters ranging from tens of nanometers up to microns.

“Minimization of the interfacial energy at the boundary of the chemical reaction front allows us to form small nuclei and then retain their diameter as the reaction proceeds, thus forming nanowires,” Yushin explained. “By controlling the volume changes, surface energy, reactivity and solubility of the reaction products, along with the temperature and pressure, we can tune conditions to produce nanowires of the dimensions we want.”

One of the attractive applications may be separator membranes for lithium-ion batteries, whose high power density has made them attractive for powering everything from consumer electronics to aircraft and motor vehicles. However, the polymer separation membranes used in these batteries cannot withstand the high temperatures generated by certain failure scenarios. As result, commercial batteries may induce fires and explosions, if not designed very carefully and it’s extremely hard to avoid defects and errors consistently in tens of millions of devices.

Using low-cost paper-like membranes made of ceramic nanowires could help address those concerns because the structures are strong and thermally stable, while also being flexible – unlike many bulk ceramics. The material is also polar, meaning it would more thoroughly wetted by various battery electrolyte solutions.

“Overall, this is a better technology for batteries, but until now, ceramic nanowires have been too expensive to consider seriously,” Yushin said. “In the future, we can improve mechanical properties further and scale up synthesis, making the low-cost ceramic separator technology very attractive to battery designers.”

Fabrication of the nanowires begins with formation of alloys composed of one reactive and one non-reactive metal, such as lithium and aluminum (or magnesium and lithium). The alloy is then placed in a suitable solvent, which could include a range of alcohols, such as ethanol. The reactive metal (lithium) dissolves from the surface into the solvent, initially producing nuclei (nanoparticles) comprising aluminum.

Though bulk aluminum is not reactive with alcohol due to the formation of the passivation layer, the continuous dissolution of lithium prevents the passivation and allows gradual formation of aluminum alkoxide nanowires, which grow perpendicular to the surface of the particles starting from the nuclei until the particles are completely converted. The alkoxide nanowires can then be heated in open air to form aluminum oxide nanowires and may be formed into paper-like sheets.

The dissolved lithium can be recovered and reused. The dissolution process generates hydrogen gas, which could be captured and used to help fuel the heating step.

Though the process was studied first to make magnesium and aluminum oxide nanowires, Yushin believes it has a broad potential for making other materials. Future work will explore synthesis of new materials and their applications, and develop improved fundamental understanding of the process and predictive models to streamline experimental work.

The researchers have so far produced laboratory amounts of the nanowires, but Yushin believes that the process could be scaled up to produce industrial quantities. Though the ultimate cost will depend on many variables, he expects to see fabrication costs cut by several orders of magnitude over existing techniques.

“With this technique, you could potentially produce nanowires for a cost not much more than that of the raw materials,” he said. Beyond battery membranes, the nanowires could be useful in energy harvesting, catalyst supports, sensors, flexible electronic devices, lightweight structural composites, building materials, electrical and thermal insulation and cutting tools.

The new technique was discovered accidentally while Yushin’s students were attempting to create a new porous membrane material. Instead of the membrane they had hoped to fabricate, the process generated powders composed of elongated particles.

“Though the experiment didn’t produce what we were looking for, I wanted to see if we could learn something from it anyway,” said Yushin. Efforts to understand what had happened ultimately led to the new synthesis technique.

In addition to those already named, the research included Alexandre Magaskinski of Georgia Tech and Gene Berdichevsky of Sila Nanotechnologies.

Research by scientists at Swansea University is helping to meet the challenge of incorporating nanoscale structures into future semiconductor devices that will create new technologies and impact on all aspects of everyday life.

Dr Alex Lord and Professor Steve Wilks from the Centre for Nanohealth led the collaborative research published in Nano Letters. The research team looked at ways to engineer electrical contact technology on minute scales with simple and effective modifications to nanowires that can be used to develop enhanced devices based on the nanomaterials. Well-defined electrical contacts are essential for any electrical circuit and electronic device because they control the flow of electricity that is fundamental to the operational capability.

Specialist research equipment and reseach images. Credit: Scienta Omicron

Specialist research equipment and reseach images. Credit: Scienta Omicron

Everyday materials that are being scaled down to the size of nanometres (one million times smaller than a millimetre on a standard ruler) by scientists on a global scale are seen as the future of electronic devices. The scientific and engineering advances are leading to new technologies such as energy producing clothing to power our personal gadgets and sensors to monitor our health and the surrounding environment.

Over the coming years this will make a massive contribution to the explosion that is the Internet of Things connecting everything from our homes to our cars into a web of communication. All of these new technologies require similar advances in electrical circuits and especially electrical contacts that allow the devices to work correctly with electricity.

Professor Steve Wilks said: “Nanotechnology has delivered new materials and new technologies and the applications of nanotechnology will continue to expand over the coming decades with much of its usefulness stemming from effects that occur at the atomic- or nano-scale. With the advent of nanotechnology, new technologies have emerged such as chemical and biological sensors, quantum computing, energy harvesting, lasers, and environmental and photon-detectors, but there is a pressing need to develop new electrical contact preparation techniques to ensure these devices become an everyday reality.”

“Traditional methods of engineering electrical contacts have been applied to nanomaterials but often neglect the nanoscale effects that nanoscientists have worked so hard to uncover. Currently, there isn’t a design toolbox to make electrical contacts of chosen properties to nanomaterials and in some respects the research is lagging behind our potential application of the enhanced materials.”

The Swansea research team1 used specialist experimental equipment and collaborated with Professor Quentin Ramasse of the SuperSTEM Laboratory, Science and Facilities Technology Council. The scientists were able to physically interact with the nanostructures and measure how the nanoscale modifications affected the electrical performance.2

Their experiments found for the first time, that simple changes to the catalyst edge can turn-on or turn-off the dominant electrical conduction and most importantly reveal a powerful technique that will allow nanoengineers to select the properties of manufacturable nanowire devices.

Dr Lord said: “The experiments had a simple premise but were challenging to optimise and allow atomic-scale imaging of the interfaces. However, it was essential to this study and will allow many more materials to be investigated in a similar way.”

“This research now gives us an understanding of these new effects and will allow engineers in the future to reliably produce electrical contacts to these nanomaterials which is essential for the materials to be used in the technologies of tomorrow.

“In the near future this work can help enhance current nanotechnology devices such as biosensors and also lead to new technologies such as Transient Electronics that are devices that diminish and vanish without a trace which is an essential property when they are applied as diagnostic tools inside the human body.”

Research managed by SUNY Polytechnic Institute (SUNY Poly) and conducted by a number of collaborating institutions has led to findings that have been named a top ten 2016 breakthrough in physics by Physics World. The publication recently named the SUNY Poly-led Institute for Nanoelectronics Discovery and Exploration’s (INDEX) “Theme I” work on the negative refraction of electrons in graphene p-n junctions as “a top ten breakthrough,” as it supports the physics for p-n junctions in graphene, which could lead to more powerful and energy efficient computing capabilities in the future.

“SUNY Poly’s position as a world class research institution is unmatched, and our faculty and students should be proud to be a part of that success,” said Dr. Bahgat Sammakia, Interim President of SUNY Polytechnic Institute. “It’s an incredible honor to have research managed by the talented people here at SUNY Poly recognized among the top ten physics breakthroughs of this past year, and I salute the SUNY Poly INDEX team and the researchers at partnering institutions who, collectively, enabled this fascinating research.”

As part of the research, scientists created a p-n junction, a building block of many modern day semiconductor-based electronic devices, in graphene, a two-dimensional honeycomb-shaped form of carbon that is incredibly strong and conductive. By ensuring that the p-n junction interface was smooth, the researchers minimized reflections, which enabled them to measure the negative refraction of electrons, an accomplishment that could one day form the basis of a new type of electronic switch, potentially replacing the transistor, which is currently the basis of computers worldwide. While this research shows that this new type of switch is possible, it could still take many years for any practical applications to result.

“We are excited that this great work of physics has been recognized by Physics World, and as part of the SUNY Poly team, we are thrilled to have solidified INDEX’s funding and look forward to continuing this important work, ” said SUNY Poly Vice President for Research Dr. Michael Liehr. “This acknowledgement is a testament not only to SUNY Poly’s ability to lead collaborations that can have significant research impact, but also to working collaboratively as research partners with other leading institutions such as Columbia University.”

The research that led to the notable findings was specifically conducted at Columbia University, the University of Virginia, and Harvard University, and was managed by SUNY Poly; Cornell University, the National Institute for Materials Science in Japan, and IBM were also recognized by Physics World for their teams’ contributions.

“This work is significant for proving the fundamental physics of the graphene p-n junction, and we are excited that the research of ‘Theme I’ of INDEX has resulted in this recognition,” SUNY Poly Interim Dean of the College of Nanoscale Science and Empire Innovation Professor of Nanoscale Science Dr. Alain Diebold said. “This is a credit to researchers Cory Dean and Jim Hone of Columbia University, who fabricated and measured the test structures using a method called magnetic steering, as well as Avik Ghosh of the University of Virginia, who modeled and simulated the data enabling the interpretation and helping to design new test structures. SUNY Poly was proud to play an enabling role.”

The research was conducted under the SUNY Poly-led umbrella of INDEX, which is one of three active centers in the Semiconductor Research Corporation’s Nanoelectronics Initiative leveraging faculty and students across ten universities. INDEX has three research areas, or themes: graphene p-n junction devices, spintronic devices, and fabrication – with a goal to develop a new switch to replace the transistor. Currently, Dr. Alain Diebold serves as INDEX’s Director, following the tenure of Dr. Michael Liehr, who had previously served as director at the Nanoelectronics Research Institute-funded center. In addition, INDEX is a Semiconductor Research Corporation (SRC) program sponsored by the Nano-Electronics Research Corporation (NERC) and the National Institute of Standards and Technology (NIST).

AGC Asahi Glass (AGC), a manufacturer of glass, chemicals and high-tech materials, today announced it has developed a diverse line of glass substrates specifically designed for semiconductor packaging applications and semiconductor manufacturing process support. The company is demonstrating the new substrates at NEPCON JAPAN 2017, opening today at Tokyo Big Sight and running through Friday, January 20. AGC’s exhibit can be found at booth W3-6 in the West Hall (1F).

Key advanced packaging technologies are poised to benefit from the AGC products. Wafer-level packaging (WLP) technology – in which the IC is packaged while still part of the wafer – has made remarkable progress with next-generation semiconductor and MEMS devices. This has resulted in a growing need for glass wafers – in particular, those that can match silicon’s coefficient of thermal expansion (CTE), thus eliminating the warping that occurs when attempting to directly laminate silicon and glass wafers whose CTE values differ.

Another target technology for the new substrates is fan-out wafer-level packaging (FOWLP), which enhances standard WLP technology to provide a smaller package footprint with improved thermal and electrical performance. It involves joining materials with different CTEs, including silicon wafers, rewiring layers and resin. As combinations and patterns vary from device to device, glass substrates that can provide the optimal CTE for each element are needed. Also, since the alkaline component of ordinary glass can cause contamination in production processes and devices, alkali-free glass is desirable in certain applications.

Designed to satisfy a wide range of customer needs, the new AGC glass substrates can be provided in rectangular and square shapes, as well as traditional round wafers, with thicknesses ranging from 0.2 mm to 2 mm. The lineup includes:

  • Glass without alkali
  • Glass products that maintain the exact same CTE as silicon through temperatures ranging from ambient air temperature to roughly 250°C
  • Glass products covering a wide range of CTE values from 3 ppm/°C to 8 ppm/°C
  • Glass with alkali
  • Glass products covering higher ranges of up to CTE 12 ppm/°C