Graphene's Electronic Limits Revealed

Physicists at the University of Maryland have thoroughly probed the conductivity of graphene—a single-atom-thick sheet of graphite—and measured key parameters that for the first time give a complete picture of the current limitations and future promise of the recently discovered electronic material (Nat. Nanotechnol., DOI: 10.1038/nnano.2008.58). Jian-Hao Chen, Michael S. Fuhrer, and coworkers report values for the resistivity (resistance to electron flow) and mobility (how fast electrons move) of graphene samples on a silicon dioxide substrate. But because graphene is just a single layer of carbon atoms, the researchers found that its very low resistivity and very high mobility are impacted by electronic interactions not only within the graphene layer but also with the substrate beneath. They anticipate that with better sample preparation techniques and less interactive substrates—silicon carbide and diamond are promising candidates—graphene's resistivity and mobility can be improved to near the material's room-temperature limits. The researchers showed that those values can surpass the low resistivity of silver and the high mobility of InSb, the current record holders, and put graphene's mobility about 100 times higher than that for silicon.