▎ 摘　　要

The graphene is a native two-dimensional crystal material consisting of a single sheet of carbon atoms. In this unique one-atom-thick material, the electron transport is ballistic and is described by a quantum relativisticlike Dirac equation rather than by the Schrodinger equation. As a result, a graphene barrier behaves very differently compared to a common semiconductor barrier. The authors show that a single graphene barrier acts as a switch with a very high on-off ratio and displays a significant differential negative resistance, which promotes graphene as a key material in nanoelectronics. (c) 2007 American Institute of Physics.