Graphene-Info: the graphene experts

In 2018, researchers at MIT demonstrated superconductivity in magic-angle bilayer graphene. Now, Dmitri Efetov of the Institute of Photonic Sciences in Barcelona, Spain, and his colleagues have replicated MIT's results and discovered even more states in magic-angle graphene. By preparing a high-quality device, Efetov’s team could measure the electronic phases more accurately and resolve previously hidden electronic states.

To realize the magic angle, the researchers use an established technique: They take one sheet of graphene and tear it in two. They then rotate one of the pieces just past the magic angle, by about 1.2°, and stack it on top of the other. In most electrical devices, the final step is annealing to clean the sample and get rid of any air bubbles between the layers. But in magic-angle graphene, with the layers misaligned by such a small angle, heating the sample snaps the graphene layers back into alignment. Instead of annealing, Efetov and his colleagues rolled the top layer down gradually, starting from one edge, rather than dropping the second layer directly down onto the first. That method squeezes out any air bubbles as they form. The result is a relative angle that varies by only 0.02° over a 10 µm device, a record for magic-angle graphene. The fabrication overall is tricky; it was reported that in three months of trying, just 2 of the 30 devices worked.

A team of researchers at IIT-Gandhinagar in India has discovered an unexpected phenomenon that could have significant implications on the existing protocols followed to synthesize graphene and other two dimensional (2D) nanomaterials.

A popular method to synthesize graphene is liquid-phase exfoliation, in which the graphite powder is mixed in a suitable liquid medium and exposed to bursts of high-intensity sound energy (ultrasonication). This ultrasonic energy delaminates the layered parent crystals into daughter nanosheets that suspend and swim in the organic solvents to form a stable dispersion of 2D nanomaterials.

UK-based AMD, which was accepted for funding via the UK Defense and Security Accelerator (DASA) in the field of “signature management”, recently received its second DASA funding in the field of Nanobarcoding, “Authenticating Critical Components”.

CEO John Lee comments: “This year has seen a rapid evolution in AMD’s involvement in the area of protecting both military and civilian personnel. Following on from our work in signature management we are now able, with the support of DASA funding, to further our efforts in our key vertical of anti-counterfeiting technologies. Both the UK & US defense agencies have been extremely supportive of our work and we look forward to continuing developing these rewarding relationships... Our work with the Materials Physics teams at Sussex and now Surrey continues to drive some very exciting areas of innovation with specific commercial applications and it looks like 2020 will see some major developments for us in a multitude of areas.”

Researchers from Iowa State University’s (ISU) Department of Mechanical Engineering, led by Dr. Jonathan Claussen, have developed a graphene-enhanced sensor that can detect organophosphates at levels 40 times smaller than the U.S. Environmental Protection Agency (EPA) recommendations. Organophosphates are certain classes of insecticides used on crops throughout the world to kill insects.

Claussen and his team have developed Salt Impregnated Inkjet Maskless Lithography (SIIML), which uses an inkjet printer to create inexpensive graphene circuits with high electrical conductivity. They add salts to the ink, which is later washed away to leave microsized divots or craters in the surface. This textured printed graphene surface is able to bind with pesticide-sensing enzymes to increase sensitivity during pesticide biosensing.

Associate professor of engineering at Texas State University,Dr. Maggie Chen, has been researching and studying durable, flexible electronic circuits in hopes of creating new antennas for NASA space travel programs. Chen’s work is expected to eventually replace the common use of silver materials in antennas. Ideally, Chen’s 3D-printed antennas would use graphene.

“With the antennas, our goal is to reduce the volume and weight of the antennas and to provide and implement a more efficient approach to the use of antennas in space,” Chen said. “The idea is we roll the antennas up, launch a satellite into space and pop them back out when in space so they can communicate with the stations on the ground.”

Global Graphene Group (G3) has announced the signing of a joint development agreement (JDA) with a major Taiwan-based manufacturer. The companies will work together to incorporate graphene-enhanced materials into polyetheretherketone (PEEK)-based products for the semiconductor industry in portions of Asia.

PEEK is a high-performance engineering thermoplastic. The addition of G3’s graphene will improve the thermoplastic’s mechanical, electrical and thermal properties. As an excellent self-lubrication material, graphene can help lower the friction ratio of PEEK/Graphene devices and reduce its wear rate significantly. It can also improve its anti-corrosion properties against harsh environments by creating a barrier to the polymer matrix.

Researchers from the Chinese Academy of Sciences have fabricated a graphene-based transistor with a Schottky emitter - a silicon-graphene-germanium transistor. Using a semiconductor membrane and graphene transfer, the team stacked three materials including an n-type top single-crystal Si membrane, a middle single-layer graphene (Gr) and an n-type bottom Ge substrate.

Device design and fabrication. Image credit: Nature Communications

The team explained that compared with previous tunnel emitters, the on-current of the Si-Gr Schottky emitter shows the maximum on-current and the smallest capacitance, leading to a delay time more than 1,000 times shorter. Thus, the alpha cut-off frequency of the transistor is expected to increase from about 1 MHz by using the previous tunnel emitters to above 1 GHz by using the current Schottky emitter. THz operation is expected using a compact model of an ideal device.