Stopping Electrons with a SuperlatticeCategory: Science & Technology
Posted: April 3, 2012 08:00AM
Researchers are quite intent on making graphene into a viable material for electronics. The atom-thick sheet of carbon has unbelievable electronic conductivity, but this is actually not a good thing for electronics. Semiconductors are used in computers because they allow the flow of electrons to change, based on their energy. Graphene just lets electrons zip by at super speed. In fact, the electrons travel so fast that relativistic quantum mechanical effects occur.
In classic mechanics, a wall is a wall and you cannot just pass through it. In quantum mechanics there is a chance for a particle to tunnel though the wall, as though it were not there. With graphene though, electrons travel so fast that they will tunnel through the barrier every time they encounter it. This phenomenon is a problem for using graphene in computers.
Researchers at the University of Arizona have discovered that using a sheet of boron nitride it is possible to block and even stop electrons on graphene. Both materials have the same hexagonal crystal structure or lattice, though the boron nitride is an insulator. What the Arizona researchers found is that by having the two materials at an angle to each other, a superlattice can be made, which introduces holes electrons cannot tunnel through. Previous research has shown how sheets of boron nitride can affect the flow of electrons on graphene, but this is a first.
There is a catch though, but it may be overcome before too long. There is no means to control the orientation the graphene and boron nitride sheets have to each other. When the researchers were making their samples, they had to use an electron microscope to see which had the proper orientation. Once a means is found to control the orientation, we could see a boom in graphene-based technology.