▎ 摘　　要

The electric properties of mono- and multi-layer graphene films were systematically studied. The current modulation increased monotonically with a decrease in the layer number due to the reduction of the interlayer scattering. The carrier mobility in the monolayer was greater than that in the multilayer due to the linear dispersion relation. On the other hand, in the monolayer, the carrier transport was significantly sensitive to the charged impurity density due to the reduction in the screening effect, which caused larger mobility variation. The reduction of the charged impurity density is thus key for high mobility. (C) 2009 The Japan Society of Applied Physics