  We discuss transport through double gated single and few layer graphene
devices. This kind of device configuration has been used to investigate the
modulation of the energy band structure through the application of an external
perpendicular electric field, a unique property of few layer graphene systems.
Here we discuss technological details that are important for the fabrication of
top gated structures, based on electron-gun evaporation of SiO$_2$. We perform
a statistical study that demonstrates how --contrary to expectations-- the
breakdown field of electron-gun evaporated thin SiO$_2$ films is comparable to
that of thermally grown oxide layers. We find that a high breakdown field can
be achieved in evaporated SiO$_2$ only if the oxide deposition is directly
followed by the metallization of the top electrodes, without exposure to air of
the SiO$_2$ layer.
