New material shares many of graphene’s unusual properties

Graphene, a single-atom-thick layer of carbon, has spawned much research into its unique electronic, optical and mechanical properties. Now, researchers at MIT have found another compound that shares many of graphene's unusual characteristics - and in some cases has interesting complementary properties to this much-heralded material.

The material, a thin film of bismuth-antimony, can have a variety of different controllable characteristics, the researchers found, depending on the ambient temperature and pressure, the material's thickness and the orientation of its growth. The research, carried out by materials science and engineering PhD candidate Shuang Tang and Institute Professor Mildred Dresselhaus, appears in the journal Nano Letters.

Like graphene, the new material has electronic properties that are known as two-dimensional Dirac cones, a term that refers to the cone-shaped graph plotting energy versus momentum for electrons moving through the material. These unusual properties - which allow electrons to move in a different way than is possible in most materials - may give the bismuth-antimony films properties that are highly desirable for applications in manufacturing next-generation electronic chips or thermoelectric generators and coolers.

In such materials, Tang says, electrons ''can travel like a beam of light,'' potentially making possible new chips with much faster computational abilities. The electron flow might in some cases be hundreds of times faster than in conventional silicon chips, he says.

Similarly, in a thermoelectric application - where a temperature difference between two sides of a device creates a flow of electrical current - the much faster movement of electrons, coupled with strong thermal insulating properties, could enable much more efficient power production. This might prove useful in powering satellites by exploiting the temperature difference between their sunlit and shady sides, Tang says.

Such applications remain speculative at this point, Dresselhaus says, because further research is needed to analyse additional properties and eventually to test samples of the material. This initial analysis was based mostly on theoretical modeling of the bismuth-antimony film's properties.