Graphene's negative resistance may enable ultra-fast, small circuits

Researchers from the University of California, Riverside developed a graphene based transistor based on negative resistance rather than trying to open up a band gap. Negative resistance is the counterintuitive phenomenon in which a current entering a material causes the voltage across it to drop. It was shown before that graphene demonstrates negative resistance in certain circumstances.

The idea is to take a regular graphene field-effect transistor (FET) and find the circumstances in which it demonstrates negative resistance. This dip in voltage is used as a kind of switch - to perform logic. The researchers showed how several graphene FETs combined can be manipulated to produce conventional logic gates. The researchers designed such circuits that can match patterns (but they have yet to actually produce them).

The NSF grants $360,000 towards graphene-based heat-removal study

The National Science Foundation (NSF) awarded a $360,000 three-year grant to three professors from the University of California, Riverside (UCR) to further study th thermal properties of graphene. The future goal of this study is to find new heat-removal approaches for electronic and optoelectronic devices.

This specific project will investigate the effect of rotation angle on the thermal conductivity of twisted bilayer graphene. The UCR team will study the possibility of suppressing the phonon coupling in twisted graphene layers, allowing for the transfer of extraordinary large heat fluxes. The phonons are quanta of crystal lattice vibrations that carry heat in graphene.

Graphene used to find the origin of 1/f noise after almost a century of research

Researcherrs from the University of California (UC Riverside) have finally (after almost a century of research) managed to find out what causes the low-frequency electronic 1/f noise (also known as pink noise or flicker noise). Using graphene sheets, it was found that 1/f noise is a surface phenomenon that shows up in situations that are thinner than 2.5 nm (at least for graphene).

Graphene was essential for this work because you can test for 1/f noise using a single sheet, and then add sheet after sheet (basically adding just one-atom to the thickness of the conductive material). This cannot be done with metal films.

Researchers create the slimmest graphene nanoribbons ever

Researchers from IBM and University of California Riverside managed to make the slimmest graphene nanoribbon (GNR) ever - just 10 nm in width. Making one is virtually impossible, and the team created a large number of GNRs in parallel. The researchers say that the arrays cover about 50% of the prototype device channel area, which means that integrated circuits based on GNRs with the required high current densities are now possible. The narrow GNRs have a bandgap of about 0.2 eV.

The process the researchers used consists of two main steps: a top-down e-beam lithography step and a bottom-up self-assembly step involving a block copolymer template comprising alternating lamellae of the polymers PS and PMMA.

Nano-Giraffe awarded in a science-is-art competition

A Ph.D. student from the University of California, Riverside' won the Science as Art competition at 2012 MRS with his 0.05 millimeter nano-giraffe structure. He said that he accidentally saw this structure, and he enhanced it with Photoshop.

In his research, Amini developed a processing technique to grow single layer graphene from a molten phase. He used a process which melted a mixture of nickel, aluminum and carbon. When the mixture solidified, the nickel and aluminum formed the body of the giraffe while the carbon crystallized as a graphite cover.