Single and double barrier structures have been realized with Ag nanostructures grown on Si(111) in combination with scanning tunneling microscopy. The series connection of a Schottky (SB) and tunneling barrier mimics a double barrier structure showing Coulomb blockade oscillations as revealed by scanning tunneling spectroscopy (STS). Although the SB remains in presence of a Ag√3×√3 reconstruction, the dI/dV characteristic turns into a single barrier structure. The Ag reconstruction provides a sufficiently high electron mobility capturing intrinsic defects which shortens the resistance of the SB. These results show that vertical transport properties, as measured with STS, are not only controlled by the structure and the bonding on the atomic scale, but depend strongly on the lateral properties of the interface as well. © 2009 The American Physical Society.