‘Mexican hat’ graphene discovery reduces processor energy use

18 May 201628 Shares

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Scientists have developed a new type of graphene-based transistor, which has ‘ultra-low power consumption’, enabling processor clock speeds to increase dramatically.

The Moscow Institute of Physics and Technology (MIPT) has been at the forefront of some of today’s key processor discoveries, with news of its latest research making for exciting times across everything from engineering to microeletronics.

Bands of bilayer graphene are shaped like a ‘Mexican hat’, with MIPT scientists looking at the capability for an infinite amount of electrons close to the hat’s edges.

Dmitry Svintsov, author of a study published in Scientific Reports, claims that the application of a tiny voltage to the gate of the transistor sees “a huge number” of electrons in this tightly packed hat rim tunnel concurrently.

This causes a sharp change in current from the application of a small voltage, and this low voltage is the reason for the record low power consumption.

More than electricity

“The point is not so much about saving electricity – we have plenty of electrical energy,” said Svintsov.

“At a lower power, electronic components heat up less, and that means that they are able to operate at a higher clock speed – not one gigahertz, but 10, for example, or even 100.”

Transistors that can operate at minuscule voltages are the holy grail in electronics at the moment, with tunnel transistors the candidates most likely to result in adequate levels of energy use.

However, as the tunnels are so small, these transistors are rarely suitable for larger circuits, with Svintsov and his colleagues hoping this discovery can change that. The key is bilayer graphene.

(A) Electron spectrum E(p) in graphene bilayer under transverse electric field and the energy dependence of its DoS. The “Mexican hat” feature in the dispersion law leads to the square-root singularities in the DoS near the band edges. Panel (B) highlights with red the electron states involved in the interband tunneling at small band overlap in graphene bilayer (left) and in a semiconductor with parabolic bands (right). The phase space for tunneling in graphene bilayer represents a ring, while in a parabolic-band semiconductor it is a point. Dashed lines indicate the tunneling transitions, red lines indicate the trajectories of the tunneling electrons in the valence band.

(A) Electron spectrum E(p) in graphene bilayer under transverse electric field and the energy dependence of its DoS. The “Mexican hat” feature in the dispersion law leads to the square-root singularities in the DoS near the band edges. Panel (B) highlights with red the electron states involved in the interband tunneling at small band overlap in graphene bilayer (left) and in a semiconductor with parabolic bands (right). The phase space for tunneling in graphene bilayer represents a ring, while in a parabolic-band semiconductor it is a point. Dashed lines indicate the tunneling transitions, red lines indicate the trajectories of the tunneling electrons in the valence band.

Bilayer graphene a promising material

“Bilayer graphene is two sheets of graphene that are attached to one another with ordinary covalent bonds,” said Svintsov.

“It is as easy to make as monolayer graphene, but due to the unique structure of its electronic bands, it is a highly-promising material for low-voltage tunnelling switches.”

In another cool discovery, last January, a team of scientists from the same university demonstrated that use of high-performance thermal interfaces to nanophotonics in microprocessors won’t necessarily be the overheating problem many were predicting.

Mexican hat image via Shutterstock

Gordon Hunt is a journalist at Siliconrepublic.com

editorial@siliconrepublic.com