Graphene's electrical properties transformed by layer alignment


— 2:08 PM on September 27, 2011

Researchers at the University of California, Riverside, have made a rather interesting accidental discovery about the electrical properties of graphene, a lattice-like arrangement of carbon atoms that has been tapped as a potential replacement for silicon in future microprocessors. Graphene's high conductivity makes it particularly attractive for such applications, but the lack of a "band gap," which would allow transistors to be turned off, presents a challenge.

When layering three graphene sheets, the researchers observed a dramatic change in the electrical properties of the material. Shifting the alignment of the top layer in the three-sheet stack by just one atom transformed the material from a conductor to an insulator, effectively creating a band gap that is now the focus of their studies. Jeanie Lau, the associate professor of physics and astronomy whose lab is responsible for the finding, likens it to discovering a tuning knob for the material. Lau isn't sure what causes the dramatic shift in electrical properties, though. Her team's findings have been published by Nature Physics.

This isn't the first time a band gap has been created with graphene. Last year, IBM researchers created a band gap in two-layer graphene by applying an external electric field.  A few years before that, Berkley Labs observed a band gap in a similar graphene structure that had been chemically doped.

Graphene's material properties hold much promise, but what about actually building the lattice structures in large volumes? Researchers at MIT are developing an "industrial-scale printing press" designed to churn out graphene sheets as large as one square kilometer. The previous record is reportedly only one square foot, so their work is certainly cut out.

   
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