The Manchester University team that first isolated graphene has discovered a way of introducing a band gap into the material that makes it a much more promising candidate for building transistors.
Graphene is famous for its astonishing list of useful characteristics – especially its conductivity. But the very free motion of the electrons has meant that it hasn’t been well suited for use in transistors. The trouble being that a transistor needs to have a significant gap between the conducting and valence bands of its electrons, so that it can be switched off. Graphene does not.
But Nobel Prize-winning researchers Andre Geim and Konstantin Novosalev have put their name to new research showing that introducing a layer of molybdenum disulphide between two sheets of graphene stops the electrons flowing normally, and acts as an off state.
The result depends on a phenomenon known as field effect tunnelling. This means that some of the electrons can tunnel through the insulating layer, but only if they have sufficient energy. They can get that energy from an applied voltage, but turn the voltage down, and so few electrons make it through that the current is effectively switched off.
The discovery holds promise for those hoping to take advantage of graphene as an alternative to silicon in electronics, the researchers say here) in the paper (published in Science on February 2nd).