Transport Properties of Multi-Graphene Films Grown on Semi-Insulating SiC

Multi-graphene films grown by sublimation on the surface of a semi-insulating 6H_SiC substrate have been studied. It is shown that pre-growth annealing of the substrate in a quasi-closed growth cell improves the structural quality of a multi-graphene film. Ohmic contacts to the film have been fabricated, and the Hall effect has been studied at low temperatures. It is found that a 2D electron gas exists in the films. It is concluded that the conductivity of the film is determined by defects existing within the graphene layer or at the interface between the graphene film and a SiC substrate.