The public defense of Quentin Wilmart, realized under the supervision of Bernard Plaçais, will take place on December 7, 2015 at 2pm in room conf IV.
The two dimensional nature and chirality of the graphene charge carriers have brought exciting opportunities for a new kind of electronics. We are now able to realize devices exploiting the Dirac nature of graphene electrons. They rely on i) the stacking of graphene on hexagonal boron nitride (hBN) for the access to the ballistic regime and ii) a full control of the doping profile using local back gate arrays. When graphene goes ballistic electrons behave like light rays, where the optical index is given by the doping and p-n junctions play the role of diopters. Geometrical optic conditions can be satisfied at room temperature provided that junctions are sharp at the scale of the Fermi wave length. I will present the realization and characterization of such devices and illustrate their potential for GHz electronics with two examples : the gated-contact transistor and the Dirac fermion pinch-off transistor. The first relies on the Klein tunneling at the contact junction; the second on the inhomogeneous doping profile in local gated graphene combined with the velocity saturation by remote hBN surface phonons.