Researchers at the Georgia Institute of Technology have produced a practically usable semiconductor material from graphene for the first time. This makes it possible to produce transistors that switch ten times faster than those made of silicon.
Advertisement
Graphene has been considered something of a miracle material since its discovery in 2004. Just a few years after the discovery of graphene, physicists Konstantin Novoselov and Andre Geim were awarded the Nobel Prize in Physics.
Graphene shines with fantastic values for strength, electrical conductivity and thermal conductivity, which should make completely new applications possible, for example in electronics. Since the material consists of a single layer of carbon atoms, these properties arise from its quasi-two-dimensional structure. The research on graphene therefore also inspired the investigation of other two-dimensional materials.
Graphene without a bandgap
However, the hopes for graphene electronics have not yet been fulfilled because there is no band gap in the band structure of graphene (unless thin, narrow bands are created from graphene, but these turn out to be too inhomogeneous). However, the function of field effect transistors, the workhorses of integrated electronic circuits, is essentially based on this band gap – an externally applied voltage ensures that the silicon can be switched between source and drain, between conducting and non-conducting.
Walter de Heer and his colleagues now managed to produce so-called epigraphs. This is a graphene layer on a silicon carbide wafer that chemically bonded with the silicon carbide and showed semiconducting properties. To do this, they developed their own manufacturing process. They describe technical details in an article in “Nature”. Silicon carbide is already used in the semiconductor industry, for example in power electronics. There are already established manufacturing processes for electronics made from this material.
The team’s measurements on a prototype field-effect transistor revealed that their graphene semiconductor has ten times greater mobility than silicon. “It’s like driving on a highway compared to a gravel road,” de Heer said in a press release. “It’s more efficient, doesn’t heat up as much and allows for higher speeds.” Processors made of this material could therefore be operated at a much higher clock frequency. However, the ratio between the current when switched on and off is only 10 to the power of 4 – ideally it should be a hundred to a thousand times larger. By optimizing the design, the researchers want to achieve ten to the sixth power. In further research, the team now wants to work on producing integrated circuits with this material.
(wst)
To home page