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Grain boundaries in graphene do not affect spin transport

Posted By Graphene Council, The Graphene Council, Wednesday, December 4, 2019
Graphene is a material that has been gaining fame in recent years due to its magnificent properties. In particular, for spintronics, graphene is a valuable material because the spins of the electrons used remain unaltered for a relatively long time. However, graphene needs to be produced on a large scale in order to be used in future devices. With that respect, chemical vapour deposition (CVD) is the most promising fabrication method.

CVD involves growing graphene on a metallic substrate at high temperatures. In this process, the generation of graphene starts at different points of the substrate simultaneously. This produces different single-crystal domains of graphene separated from one another through grain boundaries, consisting of arrays of five-, seven- or even eight-member carbon rings. The final product is, thus, polycrystalline graphene.

Is polycrystalline graphene as good as single-crystal graphene for spintronics? Grain boundaries are a significant source of charge scattering, increasing the electric resistance of the material. How do they affect spin transport?

Some experiments suggest that grain boundaries do not play a major role on spin transport. In this context, Dr Aron W. Cummings, from the ICN2 Theoretical and Computational Nanoscience Group, led by ICREA Prof. Stephan Roche, together with researchers from the Université catholique de Louvain (Belgium), have used first-principles simulations to study the impact of grain boundaries on spin transport in polycrystalline graphene. The study is published in Nano Letters.

The researchers have considered two different mechanisms by which spins could lose their original orientation (spin relaxation). One accounts for the randomisation of spins within the grains due to spin-orbit coupling, the other considers the possibility of the spins to flip due to scattering in a grain boundary. However, the researchers found that the latter case did not happen. Grain boundaries do not have any adverse effect on spin transport.

Therefore, spin diffusion length in polycrystalline graphene is independent of grain size and depends only on the strength of the substrate-induced spin-orbit coupling. Moreover, this is valid not only for the diffusive regime of transport, but also for the weakly localized one, in which quantum phenomena begin to prevail. This is the first quantum mechanical simulation confirming that the same expression for spin diffusion length holds in both regimes.

The research highlights the fact that single-domain graphene may not be a requirement for spintronics applications, and that polycrystalline CVD-grown graphene may work just as well. This puts the focus on other aspects to enhance in graphene production, such as the elimination of magnetic impurities.

Tags:  Aron W. Cummings  chemical vapour deposition  CVD  Graphene  Nano Letters  Nanoscience  polycrystalline  Stephan Roche  Universite catholique de Louvain 

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Industrial scale production of layer 2D materials via intermediate-assisted grinding

Posted By Graphene Council, The Graphene Council, Tuesday, November 26, 2019
The large number of 2D materials, including graphene, hexagonal boron nitride (h-BN), transition metal dichalcogenides (TMDCs) like MoS2 and WSe2, metal oxides (MxOy), black phosphorene (b-P), etc, provide a wide range of properties and numerous potential applications.

In order to realize their commercial use, the prerequisite is large-scale production. Bottom-up strategies like chemical vapor deposition (CVD) and chemical synthesis have been extensively explored but only small quantities of 2D materials have been produced so far.

Another important strategy to obtain 2D materials is from a top-down path by exfoliating bulk layer materials to monolayer or few layer 2D materials, such as ball milling, liquid phase exfoliation, etc. It seems that top-down strategies are most likely to be scaled-up, however, they are only suitable for specific materials.

So far, only graphene and graphene oxide can be prepared at the tons level, while for other 2D materials, they still remain in the laboratory state because of the low yield.

Therefore, it is necessary to develop a high-efficiency and low-cost preparation method of 2D materials to progress from the laboratory to our daily life.

The failure of solid lubricants is caused by the slip between layers of bulk materials, and the result of the slip is that the bulk materials will be peeled off into fewer layers. Based on this understanding, in a new research article published in the Beijing-based National Science Review ("Mass Production of Two-Dimensional Materials by Intermediate-Assisted Grinding Exfoliation"), the Low-Dimensional Materials and Devices lab led by Professor Hui-Ming Cheng and Professor Bilu Liu from Tsinghua University proposed an exfoliation technology which is named as interMediate-Assisted Grinding Exfoliation (iMAGE).

The key to this exfoliation technology is to use intermediate materials that increase the coefficient of friction of the mixture and effectively apply sliding frictional forces to the layer material, resulting in a dramatically increased exfoliation efficiency.

Considering the case of 2D h-BN, the production rate and energy consumption can reach 0.3 g h-1 and 3.01×106 J g-1, respectively, both of which are one to two orders of magnitude better than previous results.

The resulting exfoliated 2D h-BN flakes have an average thickness of 4 nm and an average lateral size of 1.2 µm. Besides, this iMAGE method has been extended to exfoliate a series of layer materials with different properties, including graphite, Bi2Te3, b-P, MoS2, TiOx, h-BN, and mica, covering 2D metals, semiconductors with different bandgaps, and insulators.

It is worth mentioning that, with the cooperation with the Luoyang Shenyu Molybdenum Co. Ltd., molybdenite concentrate, a naturally existing cheap and earth abundant mineral, was used as a demo for the industrial scale exfoliation production of 2D MoS2 flakes.

"This is the very first time that 2D materials other than graphene have been produced with a yield of more than 50% and a production rate of over 0.1g h-1. And an annual production capability of 2D h-BN is expected to be exceeding 10 tons by our iMAGE technology." Prof. Bilu Liu, one of the leading authors of this study, said, "Our iMAGE technology overcomes a main challenge in 2D materials, i.e., their mass production, and is expected to accelerate their commercialization in a wide range of applications in electronics, energy, and others."

Tags:  2D materials  Bilu Liu  CVD  Graphene  Hui-Ming Cheng  Tsinghua University 

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The Graphene Flagship Means Business

Posted By Graphene Council, The Graphene Council, Saturday, October 19, 2019

Leiden University spin-off, Crucell, is a world-famous biotechnology company. Johnson & Johnson acquired the business for close to $2.4 billion back in 2011. This mammoth sum of money highlights the potential of university or corporate spin-offs and their investment attraction.

There is a growing appetite for spin-offs and SMEs that have grown out of research. Here are four SMEs that are setting the pace in graphene and related materials (GRM) commercialisation in the Graphene Flagship.

EMBERION

Emberion develops and produces graphene photonics and electronics that revolutionise infrared photodetectors and thermal sensors. Applications include hyperspectral and thermal imaging, night vision and X-ray detection.

The business was a spin off company from Nokia. Following a long history of graphene research inside Nokia’s research organisation, the team joined the Graphene Flagship to take the work carried out on optoelectronics to the commercial market.

“Emberion was established in quite an early phase of product development,” explained Tapani Ryhänen, CEO of Emberion. “We had promising results and functional prototypes from our research and above all, we were able to get an agreement with venture capital investors.

"Emberion is focusing on various spectrometer and machine vision applications by producing novel image sensors. We provide products with broad wavelength range and low noise. Our image sensors can be used for example in agriculture, food processing and pharma industries."

During the next year, Emberion will start delivering its first imager products. The business will also commence with the Graphene Flagship GBIRCAM spearhead project, together with its partners, to bolster the readiness of graphene-enabled optoelectronics in industry.

GRAPHENEA

World leading graphene producer Graphenea, founded in 2010, was one of the first industrial partners to join the Graphene Flagship program. Graphenea participated in the proposal stages of the Graphene Flagship, collaborating closely since the inception of the EU-funded program.Business is booming for Graphenea. In 2018, the business generated €1.6 million, and is on track to grow by 25% in 2019.

Graphenea’s facilities are located in San Sebastián, Spain and Boston, USA. The 25 employees at Graphenea contribute to the successful development of graphene applications, including supplying CVD Graphene films, Graphene Field-Effect-Transistors chips (GFETs), Graphene Foundry Services (GFAB) and Graphene Oxides. Graphenea’s operation spans across more than 60 countries and a wide range of sectors.

“The collaboration between Graphenea and the Graphene Flagship has evolved over the last six years,” explained Iñigo Charola, business development director at Graphenea. “Our work has become incredibly industry-orientated, with focused spearhead projects to bring applications to market quickly and effectively.”

“Today, we are focusing not only on the production of graphene, but also developing our processing capabilities of the material. Our partnership with the Graphene Flagship provides the support to help reach this goal.” 

BEDIMENSIONAL

BeDimensional produces and develops graphene and 2D crystals for the manufacturing and energy industries. Its main target applications relate to coatings and paints and material production for energy applications.

As a start-up, BeDimensional was created as a spin-off company of the Istituto Italiano di Tecnologica (IIT).

The research group started out their research in fundamental studies of electronic properties of two-dimensional semiconductor systems. They were also investigating some possibilities to tune the interaction of hydrogen and carbon by curving a graphene sheet. For this latter study, the team were approached in the initial stages of the Graphene Flagship project to set-up a work package on hydrogen storage.

After a two-year incubation period within the institute itself, BeDimensional moved onto the market after the acquisition of 51% of its shares by the Camponovo. The definitive push towards the path of industrialisation came at the end of 2018, after the €18 million investment from Pellan Group.

So, what’s next for BeDimensional?
After closing this round of investment, BeDimensional is now fully immersed in implementing its industrial and commercial strategies. The first production line of two-dimensional crystals is already operational and the business is in the process of setting up more laboratories for research and development.

“We need to strategically position ourselves at the right level of the industrial value chains linked to each specific application,” explained Vittorio Pellegrini, founder and scientific advisor for BeDimensional. “We believe it is crucial to establish partnerships and joint ventures with appropriate global players. At the same time, we will reinforce our investment in R&D by attracting the best people on board.”

BeDimensional has a clear mission and knows how it’s going to reach its business goals. Watch this space. 

VERSARIEN

Versarien, headquartered in Cheltenham, UK, is an engineering solutions company that delivers novel technologies for industrial applications. Through subsidiary companies, Versarien delivers targeted solutions as well as research and development into new, complementary technologies.

Versarien was founded in 2010 and has been an associate member of the Graphene Flagship since 2018, collaborating closely with researchers in the project.

The company has acquired multiple businesses under the Versarien group, including two spin-offs from high-profile universities carrying out graphene research.

In 2014, 2-DTech joined the group. 2-DTech was originally formed by the University of Manchester to manufacture and supply high quality graphene for research and development. It has now grown into a commercial operation not only supplying high grade graphene and other 2-D materials, but also working on the application of graphene in product development projects.

In 2017, Versarien acquired Cambridge Graphene Ltd. from the University of Cambridge. Cambridge Graphene develops inks, composites and supercapacitors based on graphene and related materials, using processes developed at the Cambridge Graphene Centre.

The Cambridge Graphene Centre’s mission is to investigate the science and technology of graphene and other carbon allotropes, layered crystals and hybrid nanomaterials. The spin-out company has commercialised graphene inks for novel technology applications.

These two Graphene Flagship spin-offs join the numerous other companies in the Versarien group, creating a real force to be reckoned with for graphene commercialisation and business growth.

Tags:  BeDimensional  Cambridge Graphene Centre  CVD  Emberion  Graphene  Graphene Flagship  graphene oxide  Graphenea  Iñigo Charola  Leiden University  Tapani Ryhänen  Versarien  Vittorio Pellegrini 

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Grolltex Graphene Closes Oversubscribed Private Placement Financing Round

Posted By Graphene Council, The Graphene Council, Wednesday, September 11, 2019
Updated: Tuesday, September 10, 2019

Grolltex (named for ‘graphene-rolling-technologies’) is the largest commercial producer of single layer, ‘electronics grade’ graphene and graphene sensing materials in the U.S. They have announced that it has closed a non-brokered, oversubscribed private placement financing, in the form of a convertible note, with local area private investors. 

The gross proceeds of the private placement will be used for general working capital purposes and for increasing the capacity and quality testing capabilities of the company’s production facility in San Diego, California.


The company is focused on delivering inexpensive and enabling solutions to advanced nano-device and graphene sensor makers by fabricating the highest quality single layer graphene attainable, via chemical vapor deposition (or ‘CVD’).

The company is now capable of producing monolayer graphene sensors on large area plastic sheets at a cost of pennies per unit, in a high throughput and sustainable way.  Further, Grolltex is helping customers that currently produce their graphene sensors on silicon wafers, to transition that production capacity to making their sensors on large area sheets of biodegradable plastic instead, at a >100X cost savings. 

Monolayer graphene films are today seen as the most promising futuristic sensing materials for their combination of surface to volume ratio (the film is only one atom thick) and conductivity (the most conductive substance known at room temperature). Markets that are commercializing advanced sensors made of graphene include DNA sensing and editing, new drug discovery and wearable bio-monitors for glucose sensing and autonomous blood pressure monitoring via patches or watch-like wearable bracelet devices.

No securities were issued and no cash was paid as bonuses, finders’ fees, compensation or commissions in connection with the private placement.

Tags:  Biosensor  CVD  Graphene  Groltex  Sensors 

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Synthesizing single-crystalline hexagonal graphene quantum dots

Posted By Graphene Council, The Graphene Council, Monday, August 5, 2019
A KAIST team has designed a novel strategy for synthesizing single-crystalline graphene quantum dots, which emit stable blue light. The research team confirmed that a display made of their synthesized graphene quantum dots successfully emitted blue light with stable electric pressure, reportedly resolving the long-standing challenges of blue light emission in manufactured displays. The study, led by Professor O Ok Park in the Department of Chemical and Biological Engineering.

Graphene has gained increased attention as a next-generation material for its heat and electrical conductivity as well as its transparency. However, single and multi-layered graphene have characteristics of a conductor so that it is difficult to apply into semiconductor. Only when downsized to the nanoscale, semiconductor's distinct feature of bandgap will be exhibited to emit the light in the graphene. This illuminating featuring of dot is referred to as a graphene quantum dot.

Conventionally, single-crystalline graphene has been fabricated by chemical vapor deposition (CVD) on copper or nickel thin films, or by peeling graphite physically and chemically. However, graphene made via chemical vapor deposition is mainly used for large-surface transparent electrodes. Meanwhile, graphene made by chemical and physical peeling carries uneven size defects.

The research team explained that their graphene quantum dots exhibited a very stable single-phase reaction when they mixed amine and acetic acid with an aqueous solution of glucose. Then, they synthesized single-crystalline graphene quantum dots from the self-assembly of the reaction intermediate. In the course of fabrication, the team developed a new separation method at a low-temperature precipitation, which led to successfully creating a homogeneous nucleation of graphene quantum dots via a single-phase reaction.

Professor Park and his colleagues have developed solution phase synthesis technology that allows for the creation of the desired crystal size for single nanocrystals down to 100 nano meters. It is reportedly the first synthesis of the homogeneous nucleation of graphene through a single-phase reaction.

Professor Park said, "This solution method will significantly contribute to the grafting of graphene in various fields. The application of this new graphene will expand the scope of its applications such as for flexible displays and varistors."

This research was a joint project with a team from Korea University under Professor Sang Hyuk Im from the Department of Chemical and Biological Engineering, and was supported by the National Research Foundation of Korea, the Nano-Material Technology Development Program from the Electronics and Telecommunications Research Institute (ETRI), KAIST EEWS, and the BK21+ project from the Korean government.

Tags:  CVD  Graphene  KAIST  O Ok Park  quantum dots  Sang Hyuk Im 

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Graphene in Electronic Circuits

Posted By Graphene Council, The Graphene Council, Wednesday, July 31, 2019
Updated: Tuesday, July 30, 2019
Ever since graphene was discovered in 2004, researchers around the world have been working to develop commercially scalable applications for this high-performance material.

Graphene is 100 to 300 times stronger than steel at the atomic level and has a maximum electrical current density orders of magnitude greater than that of copper, making it the strongest, thinnest and, by far, the most reliable electrically conductive material on the planet. It is, therefore, an extremely promising material for interconnects, the fundamental components that connect billions of transistors on microchips in computers and other electronic devices in the modern world.

For over two decades, interconnects have been made of copper, but that metal encounters fundamental physical limitations as electrical components that incorporate it shrink to the nanoscale. “As you reduce the dimensions of copper wires, their resistivity shoots up,” said Kaustav Banerjee, a professor in the Department of Electrical and Computer Engineering. “Resistivity is a material property that is not supposed to change, but at the nanoscale, all properties change.”

As the resistivity increases, copper wires generate more heat, reducing their current-carrying capacity. It’s a problem that poses a fundamental threat to the $500 billion semiconductor industry. Graphene has the potential to solve that and other issues. One major obstacle, though, is designing graphene micro-components that can be manufactured on-chip, on a large scale, in a commercial foundry.

“Whatever the component, be it inductors, interconnects, antennas or anything else you want to do with graphene, industry will move forward with it only if you find a way to synthesize graphene directly onto silicon wafers,” Banerjee said. He explained that all manufacturing processes related to the transistors, which are made first, are referred to as the ‘front end.’ To synthesize something at the back-end — that is, after the transistors are fabricated — you face a tight thermal budget that cannot exceed a temperature of about 500 degrees Celsius. If the silicon wafer gets too hot during the back-end processes employed to fabricate the interconnects, other elements that are already on the chip may get damaged, or some impurities may start diffusing, changing the characteristics of the transistors.

Now, after a decade-long quest to achieve graphene interconnects, Banerjee’s lab has developed a method to implement high-conductivity, nanometer-scale doped multilayer graphene (DMG) interconnects that are compatible with high-volume manufacturing of integrated circuits. A paper describing the novel process was named one of the top papers at the 2018 IEEE International Electron Devices Meeting (IEDM),  from more than 230 that were accepted for oral presentations. It also was one of only two papers included in the first annual “IEDM Highlights” section of an issue of the journal Nature Electronics.

Banerjee first proposed the idea of using doped multi-layer graphene at the 2008 IEDM conference and has been working on it ever since. In February 2017 he led the experimental realization of the idea by Chemical Vapor Deposition (CVD) of multilayer graphene at a high temperature, subsequently transferring it to a silicon chip, then patterning the multilayer graphene, followed by doping. Electrical characterization of the conductivity of DMG interconnects down to a width of 20 nanometers established the efficacy of the idea that was proposed in 2008. However, the process was not “CMOS-compatible” (the standard industrial-scale process for making integrated circuits), since the temperature of CVD processes far exceed the thermal budget of back-end processes.

To overcome this bottleneck, Banerjee’s team developed a unique pressure-assisted solid-phase diffusion method for directly synthesizing a large area of high-quality multilayer graphene on a typical dielectric substrate used in the back-end CMOS process. Solid-phase diffusion, well known in the field of metallurgy and often used to form alloys, involves applying pressure and temperature to two different materials that are in close contact so that they diffuse into each other.

Banerjee’s group employed the technique in a novel way. They began by depositing solid-phase carbon in the form of graphite powder onto a deposited layer of nickel metal of optimized thickness. Then they applied heat (300 degrees Celsius) and nominal pressure to the graphite powder to help break down the graphite. The high diffusivity of carbon in nickel allows it to pass rapidly through the metal film.

How much carbon flows through the nickel depends on its thickness and the number of grains it holds. “Grains” refer to the fact that deposited nickel is not a single-crystal metal, but rather a polycrystalline metal, meaning it has areas where two single-crystalline regions meet each other without being perfectly aligned. These areas are called grain boundaries, and external particles — in this case, the carbon atoms — easily diffuse through them. The carbon atoms then recombine on the other surface of the nickel closer to the dielectric substrate, forming multiple graphene layers.

Banerjee’s group is able to control the process conditions to produce graphene of optimal thickness. “For interconnect applications, we know how many layers of graphene are needed,” said Junkai Jiang, a Ph.D. candidate in Banerjee’s lab and lead author of the 2018 IEDM paper. “So we optimized the nickel thickness and other process parameters to obtain precisely the number of graphene layers we want at the dielectric surface. “Subsequently, we simply remove the nickel by etching so that what’s left is only very high-quality graphene — virtually the same quality as graphene grown by CVD at very high temperatures,” he continued. “Because our process involves relatively low temperatures that pose no threat to the other fabricated elements on the chip, including the transistors, we can make the interconnects right on top of them.”

UCSB has filed a provisional patent on the process, which overcomes the obstacles that, until now, have prevented graphene from replacing copper. Bottom line: graphene interconnects help to create faster, smaller, lighter, more flexible, more reliable and more cost-effective integrated circuits. Banerjee is currently in talks with industry partners interested in potentially licensing this CMOS-compatible graphene synthesis technology, which could pave the way for what would be the first 2D material to enter the mainstream semiconductor industry.

Tags:  2D materials  CVD  Graphene  Graphite  Junkai Jiang  Kaustav Banerjee  Semiconductor  UC Santa Barbara 

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Step right up for bigger 2D sheets

Posted By Graphene Council, The Graphene Council, Thursday, March 7, 2019
Rice University researchers determined complementarity between growing hexagonal boron nitride crystals and a stepped substrate mimics the complementarity found in strands of DNA. The Rice theory supports experiments that have produced large, oriented wafers.

Very small steps make a big difference to researchers who want to create large wafers of two-dimensional material. Atom-sized steps in a substrate provide the means for 2D crystals growing in a chemical vapor furnace to come together in perfect rank. Scientists have recently observed this phenomenon, and now a Rice University group has an idea why it works.

Rice materials theorist Boris Yakobson and researcher Ksenia Bets led the construction of simulations that show atom-sized steps on a growth surface, or substrate, have the remarkable ability to keep monolayer crystal islands in alignment as they grow. If the conditions are right, the islands join into a larger crystal without the grain boundaries so characteristic of 2D materials like graphene grown via chemical vapor deposition (CVD). That preserves their electronic perfection and characteristics, which differ depending on the material.

Atom-sized steps in a substrate provide the means for 2D crystals growing in a chemical vapor furnace to come together in perfect rank. Scientists have recently observed this phenomenon, and now a Rice University group has an idea why it works.

Rice materials theorist Boris Yakobson and researcher Ksenia Bets led the construction of simulations that show atom-sized steps on a growth surface, or substrate, have the remarkable ability to keep monolayer crystal islands in alignment as they grow.

If the conditions are right, the islands join into a larger crystal without the grain boundaries so characteristic of 2D materials like graphene grown via chemical vapor deposition (CVD). That preserves their electronic perfection and characteristics, which differ depending on the material.

The Rice theory appears in the American Chemical Society journal Nano Letters.The investigation focused on hexagonal boron nitride (h-BN), aka white graphene, a crystal often grown via CVD. Crystals nucleate at various places on a perfectly flat substrate material and not necessarily in alignment with each other.

However, recent experiments have demonstrated that growth on vicinal substrates -- surfaces that appear flat but actually have sparse, atomically small steps -- can align the crystals and help them merge into a single, uniform structure, as reported on arXiv. A co-author of that report and leader of the Korean team, Feng Ding, is an alumnus of the Yakobson lab and a current adjunct professor at Rice.

But the experimentalists do not show how it works as, Yakobson said, the steps are known to meander and be somewhat misaligned.

"I like to compare the mechanism to a 'digital filter,' here offered by the discrete nature of atomic lattices," he said. "The analog curve that, with its slopes, describes a meandering step is 'sampled and digitized' by the very grid of constituent atomic rows, breaking the curve into straight 1D-terrace segments. The slope doesn't help, but it doesn't hurt. Surprisingly, the match can be good; like a well-designed house on a hill, it stands straight.

"The theory is simple, though it took a lot of hard work to calculate and confirm the complementarity matching between the metal template and the h-BN, almost like for A-G-T-C pairs in strands of DNA," Yakobson said.

It was unclear why the crystals merged into one so well until simulations by Bets, with the help of co-author and Rice graduate student Nitant Gupta, showed how h-BN "islands" remain aligned while nucleating along visibly curved steps.

"A vicinal surface has steps that are slightly misaligned within the flat area," Bets said. "It has large terraces, but on occasion there will be one-atom-high steps. The trick by the experimentalists was to align these vicinal steps in one direction."

In chemical vapor deposition, a hot gas of the atoms that will form the material are flowed into the chamber, where they settle on the substrate and nucleate crystals. h-BN atoms on a vicinal surface prefer to settle in the crook of the steps.

"They have this nice corner where the atoms will have more neighbors, which makes them happier," Bets said. "They try to align to the steps and grow from there.

"But from a physics point of view, it's impossible to have a perfect, atomically flat step," she said. "Sooner or later, there will be small indentations, or kinks. We found that at the atomic scale, these kinks in the steps don't prevent h-BN from aligning if their dimensions are complementary to the h-BN structure. In fact, they help to ensure co-orientation of the islands."

Because the steps the Rice lab modeled are 1.27 angstroms deep (an angstrom is one-billionth of a meter), the growing crystals have little trouble surmounting the boundary. "Those steps are smaller than the bond distance between the atoms," Bets said. "If they were larger, like two angstroms or higher, it would be more of a natural barrier, so the parameters have to be adjusted carefully."

Two growing islands that approach each other zip together seamlessly, according to the simulations. Similarly, cracks that appear along steps easily heal because the bonds between the atoms are strong enough to overcome the small distance.

Any path toward large-scale growth of 2D materials is worth pursuing for an army of applications, according to the researchers. 2D materials like conductive graphene, insulating h-BN and semiconducting transition metal dichalcogenides are all the focus of intense scrutiny by researchers around the world. The Rice researchers hope their theoretical models will point the way toward large crystals of many kinds.

The U.S. Department of Energy (DOE) supported the research. Computer resources were provided by the National Energy Research Scientific Computing Center, supported by the DOE Office of Science, and the National Science Foundation-supported DAVinCI cluster at Rice, administered by the Center for Research Computing and procured in partnership with Rice's Ken Kennedy Institute for Information Technology.

Tags:  Boris Yakobson  CVD  Graphene  Ksenia Bets  Rice University  U.S. Department of Energy (DOE) 

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Grolltex Drives Dramatic Increase of Single Layer CVD Graphene Production

Posted By Graphene Council, The Graphene Council, Monday, February 25, 2019
Updated: Monday, February 25, 2019

Graphene and 2D materials producer,Grolltex has completed its recent capacity expansion and released production for 30,000 eight-inch wafer equivalents per year at its CVD monolayer fabrication facility in San Diego, California. This ‘single atomic layer’ type of graphene is used in advanced electronics and other nano-devices and supports many use cases in wearables, IoT, photonics, semiconductors, biosensing and other next generation devices.

“This is the only commercial CVD monolayergraphene production facility in California and in fact it is the largest capacity plant of its kind in the U.S.”, said CEO, Jeff Draa. “Demand for our electronics grade graphene has never been better.  Our production lines are capable of producing single layer graphene or single layer hexagonal Boron Nitride”.
Otherwise known as ‘white graphene’, hexagonal Boron Nitride (or ‘hBN’) is the single atom thick insulator complement to graphene, which is a conductor.  The material hBN also has many other interesting characteristics, including being highly transparent, very strong, possesses anti-microbial and flame-retardantproperties and is additionally a performance accelerator for graphene.  The Grolltex factory expansion supports the growth, production and transfer of both of thesesingle layer materials.

“Maybe even more exciting, we currently have four active evaluations where our customers’advanced nano-factories are testing our graphene for use as the basis for their final devices and each factory eval is going very well”, said Draa.  “The biosensing area is an early adopter for our graphene, as evidenced by customers using our material to detect DNA, find diseases in blood, monitor glucose in sweat in the form of a wearable patch and validating the safety and efficacy of new drugs in previously unthinkably short times and low costs.”

Grolltex, short for ‘graphene-rolling-technologies’, makes large area, single atom thick graphene sheets using chemical vapor deposition or ‘CVD’; essentially the process is depositing gas in a chamber, then allowing it to cool, which leaves a continuous one atom thick layer of carbon on a target substrate.  This type of graphene is highly valued for its electrical characteristics, strength and flexibility and some see it as‘next generation silicon’.

The company uses patented research and techniques initially developed at the University of California, San Diego, to produce high quality, single layer graphene, hexagonal Boron Nitride and other 2D materials and products.  The company is a practitioner of, and specializes in, exclusively sustainable graphene production methods and is committed to advancing the field of graphene to improve the future of leading-edge materials science and product design through the optimization of single atom thick materials.

Tags:  Biosensor  CVD  Graphene  Grolltex  Jeff Draa  Sensors 

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Graphene Commercialization Conference in Berlin

Posted By Graphene Council, The Graphene Council, Thursday, February 21, 2019

Like many advanced materials, there is a significant learning curve to advance promising lab results into real commercial products. This includes a learning experience from the manufacturer, for cost-effective high-volume production, and a learning experience for the end-user, to establish the value and utilization of this novel material.   

IDTechEx have been following the graphene market throughout this learning experience, and the 13th edition of their commercially focussed B2B graphene conference, Graphene & 2D Materials, will be held from 10 - 11 April 2019 in Berlin, Germany. 

Once again, The Graphene Council will be there to help educate stakeholders on the value that graphene enhanced materials deliver, as well as to publicly announce the launch of the Verified Graphene Producer program. 



During the previous 12 conferences, the attendees have heard from all the main market players and end-users, with key market announcements made and technical insights provided. As the market reaches a turning point, this becomes more significant as the headlines have greater global impact.   

This combined conference and exhibition stands at a crucial point in the history of the graphene market. As laid out in a previous article, attendees will hear many relevant talks including those from: BASF, Sixth Element, NanoXplore, Avanzare, Sixonia Tech, Mitsubishi Electric, Samsung, First Graphene, and many more.   

Below are some selected indicators that the hype is turning to commercial reality for graphene. This includes the breaking of the scale vs orders dilemma, notable use-cases as a heat spreader, polymer additive, corrosion resistant coating, or enhanced battery electrode, and the upturn in investment and acquisitions. The specific news and outcomes for these indicators have all been seen at this world leading conference series and will continue to be added into the 2019 events.

2D materials are a diverse family, the event will include presentations on graphene nanoplatelets, graphene oxide (GO), reduced graphene oxide (rGO), and CVD graphene films. This includes perspectives and advancements multiple sections of the current and future supply chain: 

Material manufacturing: Attendees will hear from both established manufacturers looking to scale-up proceedings and new entries. For example, this includes NanoXplore and their 10,000 tpa plant announcement and Sixonia Tech a German university spin-out company working on electrochemical exfoliation. 

Intermediary formation: suspensions, polymer masterbatches and more are the most useful form of graphene-based products for many end-users. Attendees will hear more about this important step throughout the presentations. For example, Avanzare will discuss masterbatches for the polymer composite industry and Sixth Element provide suspensions to form heat spreaders and coatings. 

Integration and end-use application: How the materials are used, and the potential applications are very diverse. The conference will cover this in many applications from the use in energy storage, to polymer additives, electronic devices, thermal interface materials, and more all in discussion. 

Material sourcing and market opportunities: Many graphite mining companies are moving downstream and investing heavily to make this market a success. First Graphene are one such example of a vertically integrated company that will be presenting. Similarly, large materials companies are partnering or positioning themselves to utilise graphene products. Delegates will hear detailed analysis and perspectives of this industry from numerous speakers including from the likes of BASF.

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Tags:  Avanzare  BASF  CVD  First Graphene  Graphene  Mitsubishi Electric  NanoXplore  rGO  Samsung  Sixonia Tech  Sixth Element 

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Open-source automated chemical vapor deposition system for the production of two-dimensional nanomaterials

Posted By Graphene Council, The Graphene Council, Wednesday, January 30, 2019
Updated: Tuesday, January 29, 2019
A research group at Boise State University led by Assistant Professor David Estrada of the Micron School of Materials Science and Engineering has released the open-source design of a chemical vapor deposition (CVD) system for two-dimensional (2D) materials growth, an advance which could lower the barrier of entry into 2D materials research and expedite 2D materials discovery and translation from the benchtop to the market.

2-dimensional materials are a class of materials that are one to a few atoms thick. The pioneering work of Nobel Laureates Andre Geim and Konstantin Novoselov in isolating and measuring the physical properties of graphene – a 2D form of carbon arranged in a hexagonal crystal structure - ignited the field of 2D materials research

While 2D materials can be obtained from bulk van der Waals crystals (e.g. graphite and MoS2) using a micromechanical cleavage approach enabled by adhesive tapes, the community quickly realized that unlocking the full potential of 2D materials would require advanced manufacturing methods compatible with the semiconductor industry’s infrastructure.

Chemical vapor deposition is a promising approach for scalable synthesis of 2D materials – but automated commercial systems can be cost prohibitive for some research groups and startup companies. In such situations students are often tasked with building custom furnaces, which can be burdensome and time consuming. While there is value in such endeavors, this can limit productivity and increase time to degree completion.

A recent trend in the scientific community has been to develop open-source hardware and software to reduce equipment cost and expedite scientific discovery. Advances in open-source 3-dimensional printing and microcontrollers have resulted in freely available designs of scientific equipment ranging from test tube holders, potentiostats, syringe pumps and microscopes. Estrada and his colleagues have now added a variable pressure chemical vapor deposition system to the inventory of open-source scientific equipment.

“As a graduate student I was fortunate enough that my advisor was able to purchase a commercial chemical vapor deposition system which greatly impacted our ability to quickly grow carbon nanotubes and graphene. This was critical to advancing our scientific investigations,” said Estrada. “When I read scientific articles I am intrigued with the use of the phrase “custom-built furnace” as I now realize how much time and effort graduate students invest in such endeavors.”

The design and qualification of the furnace was accomplished by lead authors Dale Brown, a former Micron School of Materials Science and Engineering graduate student, and Clinical Assistant faculty member Lizandra Godwin, with assistance from the other co-authors. The results of their variable pressure CVD system have been published in PLoS One ("Open-source automated chemical vapor deposition system for the production of two- dimensional nanomaterials") and include the parts list, software drivers, assembly instructions and programs for automated control of synthesis procedures. Using this furnace, the team has demonstrated the growth of graphene, graphene foam, tungsten disulfide and tungsten disulfide – graphene heterostructures.

“Our goal in publishing this design is to alleviate the burden of designing and constructing CVD systems for the early stage graduate student,” said Godwin. “If we can save even a semester of time for a graduate student this can have a significant impact on their time to graduation and their ability to focus on research and advancing the field.”

“We hope others in the community can improve on our design by incorporating open-source software for automated control of 2D materials synthesis,” said Estrada. “Such an improvement could further reduce the barrier to entry for 2D materials research.”

Tags:  2D materials  Boise State University  CVD  Graphene 

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