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 SiO2. We perform a statistical study that demonstrates how—contrary to expectations—the breakdown field of electron-gun evaporated thin SiO2 films is comparable to that of thermally grown oxide layers. We find that a high breakdown field can be achieved in evaporated SiO2 only if the oxide deposition is directly followed by metallization of the top electrodes, without exposure of the SiO2 layer to air.