摘要： The ?ow of free charge carriers, i.e., electrons in the conduction band or holes in the valence band, in a semiconductor that is subject to an electric ?eld is accelerated by the electric field but is hindered by scattering events. In a semiconductor, free carriers accelerate in the presence of an electric field. The randomly distributed scattering centers, such as impurities and defects, act as a counter force that decelerates and de?ects the carriers. When the steady state is eventually reached under a constant electric field, a constant ?ow of carriers is achieved. In graphene, by contrast, charge carriers on the Dirac cone have a constant speed and do not accelerate or decelerate in response to the electric field or the scattering centers; instead, the effect of the electric field is rather to align the motion of carriers to the direction of the electric field, and the scattering centers act as a source to disturb this alignment process. This process is well captured by the Boltzmann transport equation, which has successfully described many statistical behaviors of carriers in metals and semiconductors. The purpose of this chapter is to describe the electronic properties of graphene, starting from the Boltzmann transport equation.