The current and the shot noise in a graphene sheet were analyzed in the ballistic regime for arbitrary voltage drops between leads and the sheet in the limit of infinite aspect ratio of the sheet width $W$ to its length $L$, when quantization of transversal wave vectors is not essential. The cases of coherent and incoherent ballistic transport were compared. At high voltages the difference with coherent transport is not essential. However, at low voltages conductance and Fano-factor dependences for incoherent transport become nonmonotonous so that the conductance has a minimum and the Fano factor has a maximum at nonzero voltage bias.

• Received 6 May 2008

DOI:https://doi.org/10.1103/PhysRevB.77.233408