Transport properties of graphene in the high-current limit.

We present a detailed study of the high-current transport properties of graphene devices patterned in a four-point configuration. The current tends to saturate as the voltage across graphene is increased but never reaches the complete saturation as in metallic nanotubes. Measurements are compared to a model based on the Boltzmann equation, which includes electron-scattering processes due to charged and neutral impurities, and graphene optical phonons. The saturation is incomplete because of the competition between disorder and optical phonon scattering.