A team of An international team of scientists has discovered what they claim is a new route to producing ultra-low-power transistors using a graphene-based composite material.
Scientists around the world are looking for innovative ways to come up with techniques to produce low power electronics not only to battle the overheating issues of small electronics components and products, but also to conserve energy.
One of the main issues with the semiconductor industry is their battle to keep the transistors that are getting ever so small from overheating while they are being used in products. The primary reason why these transistors and transistor-based electronics get overheated is the smaller and smaller packages in which they are being built and sold.
Researchers at University of York and Roma Tre University have published a study in journal Physical Review Letters wherein they describe a solution to this problem. They say that the answer to the semiconductor industry issues pertaining to overheating lies in composite materials built from monolayers of graphene and the transition metal dichalcogenide (TMDC). According to the team, these materials could be used to achieve a fine electrical control over the electron’s spin – its tiny compass needle.
This could ultimately lead the way to much needed low-energy consumption electronics. Scientists say their findings show that the application of small voltages across the graphene layer induces a net polarization of conduction spins. This will instigate substantial interest among the spintronics community.
The electron’s spin is like a tiny, point-like magnet which can point only in two directions, up or down. In materials where a major fraction of electrons’ spins is aligned, a magnetic response is produced, which can be used to encode information.
‘Spin currents’ – built from ‘up’ and ‘down’ spins flowing in opposite directions – carry no net charge, and therefore in theory, produce no heating. The control of spin information would therefore open the path towards ultra-energy-efficient computer chips.
The team of researchers showed that when a small current is passed through the graphene layer, the electrons’ spin polarize in plane due to ‘spin-orbital’ forces brought about by the proximity to the TMDC base. They also showed that the efficiency of charge-to-spin conversion can be quite high even at room temperature.
Scientists say their calculations demonstrate that graphene combined with the transition metal dichalcogenides is an ideal platform where abstract theoretical principles may find immediate application in showing the way to experimental and technological development. Current-induced spin polarization in non-magnetic media was first demonstrated in 2001 in semiconductors and, more recently, in metallic hetero-interfaces. Now the researchers predict that a similar effect occurs in graphene on TMDC monolayer.
Surprisingly they found that the unique character of electronic states in graphene enable charge-to-spin conversion efficiency of up to 94 per cent. This opens up the possibility of a graphene-based composite material becoming the basis for ultra-compact and greener spin-logic devices.