Graphene CVD sheets - updates and market status - Page 11

Graphene-Info is happy to introduce a new feature: Experts Roundup. We asked several graphene professionals to answer a graphene related question. We hope this will prove to be an interesting read and can help shed light on the nooks and cranks of the graphene industry. Enjoy!

Do you think CVD will ever be a viable way to mass produce commercial graphene sheets?

Gonçalo Gonçalves, product marketing specialist, Aixtron: Chemical vapour deposition has been used for several decades in the semiconductor industry to deposit high-quality thin-films. This technique is known to provide superior process reliability and throughput which are key requirements in the manufacturing of integrated circuits. Since 2004, graphene has emerged as a wonder material with an impressive number of potential applications across several fields. The discovery of a CVD route to produce graphene has also been an important achievement towards the integration of this carbon nanomaterial into semiconductor devices. With the advance of the graphene field from basic to applied research new and more complex challenges arise, especially in the integration reliability. CVD technique will find its way to mass production of graphene once these challenges are addressed and the benefits of graphene in semiconductor devices are unveiled.

Researchers at Rice University have created rivet graphene, 2D carbon that incorporates carbon nanotubes for strength and carbon spheres that encase iron nanoparticles, which enhance both the material’s portability and its electronic properties.

Transferring graphene grown via CVD is usually done with a polymer layer to keep it from wrinkling or ripping, but the polymer tends to leave contaminants behind and degrade graphene’s abilities to carry a current. According to the Rice team, rivet graphene proved tough enough to eliminate the intermediate polymer step, and the rivets also make interfacing with electrodes far better compared with normal graphene’s interface, since the junctions are more electrically efficient. Finally, the nanotubes give the graphene an overall higher conductivity. So for using graphene in electronic devices, this is said to be an all-around superior material.

Researchers at the Indian Institute of Science (IISc) have developed a new type of packaging that uses a single layer of graphene to protect packaged goods from moisture. The newly developed material is capable of preventing water molecules from entering packaged products, like electronics and medicines.

For the development of the new material, the researchers synthesized a single layer of graphene via CVD, and used a simple and scalable process to convert the graphene to a polymer film. Water vapour permeated the material at a rate of less than 10-6gm per m² every day. The team conducted an accelerated aging test, which demonstrated that an organic photovoltaic device wrapped in the graphene-infused film would have a lifetime of more than a year. This was reported in contrast to goods packed in polymer without the graphene layer, which were said to offer a lifespan of just 30 minutes.

Researchers from the Israeli Technion University developed a novel and rapid method to optically visualize CNTs and graphene. The idea is that growing pNBA nanocrystals - which are optically visible on top of the CNTs or graphene sheets. This allows the crystals to be viewed by dark-field optical microscopy.

The pNBAs NCs can be easily removed - and the original material is not effected by this process. But it allows much easier study of graphene, and can also be used to aid production processes as it is a scalable, fast and cost-effective process. The video below shows how growing those NCs on carbon nanotubes makes the tubes visible.

NanoIntegris, a subsidiary of Raymor Industries, recently announced the launch of PureWave Graphene, a substrate-free graphene grown in a plasma reactor, whose specifications are said to approach those of CVD single-layer graphene.

The unique plasma process used to grow PureWave Graphene nanoplatelets is reportedly easy to scale and produces a low cost product. The material contains low oxygen content (1%) and ppm metal impurity levels. The unique growth process based on plasma allows to produce this material at over 100 g/hour. This product is immediately available for research in gram or kg quantities, but lower prices for industrial applications will be unveiled by the end of the year.

Spain-based Graphenea announced reduced prices on products and increased production capacity in 2016. Improving the material quality of staple products remains a key strategy for Graphenea, alongside limited strategic expansion of the product offering.

Graphenea states that improvements in process productivity will lead to reduced graphene prices this year. In particular, the price of CVD graphene film will decrease in all categories by 23% on average this year, as the company intends to provide a very competitive offer on all substrates and sizes to support their customers’ research. Prices of graphene on custom substrates will decrease by 27%, making it easier for researchers to work on their own substrate. The price of graphene oxide (GO) for research will decrease by 33% on average. 

Researchers at the University of Manchester have demonstrated that graphene can simplify the production of heavy water and help clean nuclear waste by filtering different isotopes of hydrogen. The process could assist in producing heavy water for nuclear power plants with ten times less energy, making it simpler and cheaper.

Membranes made from graphene can act as a sieve, separating protons nuclei of hydrogen from heavier nuclei of hydrogen isotope deuterium. Deuterium is in wide use in analytical and chemical tracing technologies and, also, as heavy water required in thousands of tons for operation of nuclear power stations. The heaviest isotope, tritium, is radioactive and needs to be safely removed as a by-product of electricity generation at nuclear fission plants. Future nuclear technology is based on fusion of the two heavy isotopes.

Researchers involved in the 10.6 million Euro European research project called GRAFOL have reportedly demonstrated a cost-effective roll-to-roll production tool capable of making large sheets of graphene on an industrial scale. The tool operates at atmospheric pressure and at reduced operating temperature, and is proclaimed by the researchers "the best route to low-cost manufacture".

Graphene-enhanced perovskite PV

The project team also believes that graphene could be used as a substitute for transparent indium tin oxide (ITO) electrodes used in organic LEDs (OLEDs), enabling flexible designs while helping reduce dependency on ITO. In addition, the team showed that it is possible to adapt the CVD method to grow graphene on 300 mm-diameter silicon wafers the standard size currently used in the semiconductor industry. That suggests the potential to integrate graphene in silicon photonics platforms, as well as flexible thin-film solar cells with transparent electrodes (like perovskite PVs, for example).

Researchers at the University of Belgrade in Serbia have built the world’s first graphene-based condenser microphone, relying on graphene's ability to detect faint and high frequency sound waves. The microphone is about 32 times more sensitive than traditional nickel microphones over a range of audible frequencies. The scientists also say that in the future, graphene microphones may be able to pick up sound well beyond the range of human hearing.

The researchers used a CVD process to create sheets of graphene on a nickel foil substrate. They then etched the nickel away and placed the remaining graphene sheet (about 60 layers thick) in a commercial microphone casing, where it acts as a vibrating membrane, converting sound to electric current. Albeit just a prototype for now, this graphene mic boasts 15 decibels higher sensitivity than commercial microphones, at frequencies of up to 11 kHz. What's even more interesting is that model simulations indicate that a far more sensitive graphene microphone is theoretically possible. At 300 layers thick, a graphene vibrating membrane may be able to detects frequencies of up to 1MHz — approximately fifty times higher than the upper limit of human hearing.

Graphene 3D Lab has announced Graphene Flex Foam, a new commercial product that will be available through Graphene Laboratories’ e-commerce site, Graphene Supermarket. The new product is described as a Multilayer Freestanding Flexible Graphene Foam, that brings together a conductive elastomer composite with ultra-light graphene foam.

The foam, a highly conductive 3D chemical vapor deposition (CVD), together with the composite, brings together the best of several worlds of graphene usage. As a flexible foam, the material is both lightweight and reconfigurable, adding to ease of use and handling, with a porous structure. The Graphene Flex Foam could be used in conjunction with other graphene-related materialssuch as Graphene 3D Lab’s filament offeringsin the creation of electronics and other conductive products.