Transport localization in heterogeneous Schottky barriers of quantum-defined metal films

The nanometric localization of current transport in heterogeneous Schottky barriers was obtained by the combination of the electric field localization at the apex of a biased conductive atomic force microscopy (c-AFM) tip and of the metal films high-resistivity properties. An abrupt increase of the resistivity, modeled by a quantum-mechanical approach, was measured in Au thin films with a thickness below 10 nm. For Au ultrathin film resistivity, exceeding by two orders of magnitude the bulk value, the nanometric localization of the current transport occurs. This physical effect represents the basic principle of a microscopy approch for two-dimensional Schottky barrier height mapping, which is alternative to conventional ballistic electron emission microscopy ( BEEM). A spatial resolution in the order of the tip diameter ( 10 - 20 nm) is demonstrated by considering the realistic description of the system ( physical and geometrical). Schottky barrier inhomogeneities in a Au/4H-SiC system were imaged with an energy resolution better than 0.1 eV.