GNRs - Page 7

Researchers from the University of Nebraska-Lincoln developed a chemical process to produce graphene nanoribbons (GNRs). This bottom-up method can be used to produce very narrow GNRs (2 nanometers wide). The researchers say it is easy to scale up their process.

The team is now testing their ribbons for applications in electronics, gas sensors and solar cells. The electronic properties of their GNRs can be tuned by changing the synthetic conditions.

Researchers from France, the US and Germany managed to produce graphene ribbons (GNRs) in which electrons move freely. Those ballistic-at-room-temperature ribbons (ballistic means that there is no resistance) can be produced easily and in large volume, and may find many applications in electronics.

The GNRs are 40 nm wide and feature very high structural quality. The main challenge was to ensure that the edges of the ribbons remained highly ordered. To achieve that, the researcher started with silicon carbide as a substrate, which was etched to have nanometer-deep steps. The graphene ribbons where synthesized directly on the sidewalls of these steps.

Researchers from the University of Utah developed a new way to develop large arrays of graphene nanoribbons (GNRs), aiming for applications in photodetectors. Their method can directly write a large array of 15nm GNRs on a multilayer epitaxial graphene sheet using Focused Ion Beam (FIB).

The researchers accelerated ga+ ions to 30 keV in vacuum using a FEI Helios NanoLab 650 dual-beam FIB machine. This removed carbon atoms from the graphene sheet with a 1.3 sputtering yield (carbon/Ga+ ratio). This technology can be easily transferred to pattern other graphene nanostructures such as spheres, rings and blocks.

Researchers from Rice University in collaboration with Lockheed Martin developed a new graphene based compound that can be used as a deicing (ice protection) coating for marine and airborne radars.

Currently most radar domes use ceramic alumina for deicing, but it takes a lot of power to heat them if they are coated with ice because they are poor conductors. The new compound is based on graphene nano-ribbons (GNRs) and polyurethane car paint. The car paint helps the graphene stay on the radar dome.

Researchers from the Max Planck Institute for Polymer Researcher developed a new method to produce very long and well-defined graphene nanoribbons (GNRs). The resulting defect-free ribbons are liquid-phase-processable and could enable effective transistors and other electronic devices.

The new method is a bottom-up one - synthesizing graphene ribbons from molecular building blocks. This method is a modification to the solution-mediated production method developed in 2011 by the same group.

Researchers from the University of Pennsylvania developed a new sensitive DNA sensor (sequencer) made from graphene drilled with nanopores. The same team already developed such a sensor in 2010, but this new method increases sequencing speed dramatically.

The idea is that the researchers have now measured current directly from the graphene, whereas before they measured ionic current in the solution as it goes through the pore. The researchers use graphene nanoribbons (GNRs), and when they pass a DNA base through the material, it modules the electrical current - in a different way for each base. The current in this method is a thousand times higher than in the previous method, which means measurements can be done a thousand times faster.

Researchers from UC Santa Barbara are introducing a new all-graphene integrated circuit design schema. The researchers suggest a fabrication process that starts with a single-layer graphene sheet, then etches it into ribbons (which turn to semiconductors or metals, depends on the width of the ribbons) and finally metal and gate dielectric are deposited and patterned. They say this design may allow much smaller transistors and interconnects than what's possible with silicon transistors and metal interconnects. They hope this design can be realized in the "near future".

One of the big advantages of this process is that it uses just graphene to create both the semiconducting transistors and the metal interfaces. This will result in lower interface/contact resistances. The researchers presented a study with performance evaluation - those circuits achieved a 1.7 times higher signal-to-noise margin and 1-2 decades lower static power consumption over current CMOS technology.

A few month ago we reported on Carbyne, a chain of carbon atoms linked either by alternate triple and single bonds or by consecutive double bonds, which was found to be twice as strong as graphene. Carbyne is difficult to synthesize (it does not exist in nature, but it may exist in interstellar space) but a few years ago researchers managed to make carbyne chains up to 44 atoms long in solution.

Now researchers from Rice University have performed more theoretical calculations on this new material. They say that a Carbyne nano-rod (also called nano-ropes) is pretty much like a very thin (one-atom wide) graphene ribbon. When you twist this nano-rod, you change the band gap of the material.

Researchers from Rice University have used graphene nanoribbons (GNRs) to enhance a polymer material (thermoplastic polyurethane, or TPU) and make it more impermeable to pressurized gas. This could lead to much lighter gas tanks used in automobiles, soda bottles and even beer.

The researchers say that by adding the GNRs to the TPU, it made it a thousand times harder for gas molecules to escape through the material - even though the GNRs amount to 0.5% of the composite's weight. The GNRs were evenly dispersed through the material and were simply blocking the path for the gas molecules (graphene is totally impermeable, even for helium atoms).

Researchers from the Universities of Bielefeld and Ulm (both in Germany) developed a new way to produce graphene using aromatic molecules. This new process enables the production of large sheets and also small flakes, quantum dots and nanoribbons (GNRs). It could also be used to create multi-layered graphene.

The researchers start with copper single-crystals or low-cost polycrystalline copper foils as substrates. They then deposit aromatic biphenyl thiol molecules in a self-organised single layer. Finally, the irradiate the deposited materials using low-energy electrons and then thermal process it. This turns the bipheyl thiol into graphene.