Control Molecule-based Transport for Future Molecular Devices

In this review, possibilities to modify intentionally the electronic transport properties of metal/molecule/metal devices (MMM devices) are discussed. Here especially the influence of the metal work function, the metal-molecule interface, the molecule dipole and different tunneling mechanisms are considered. A route to evaluate the effective surface work function of metal-molecule systems is given and, based on experimental results, an exemplary estimation is performed. The electron transport across different metal-molecule interfaces is characterized by relating transmission coefficients extracted from experimentally derived molecular conductances, decay constants or tunneling barrier heights. Based on the reported results the tunneling decay constant can be assumed to be suitable to characterize intrinsic molecular electron transport properties, while the nature of the metal-molecule contacts is properly described by the transmission coefficient. A clear gradation of transmission efficiencies of metal-anchoring group combinations can be given

Geometric shadowing from rippled SrRuO3/SrTiO3 surface templates induces self-organization of epitaxial SrZrO3 nanowires

Structure, morphology, and conductivity of SrZrO3 nanowires self-organized on rippled SrRuO3/SrTiO3 surface templates by pulsed laser deposition are investigated by transmission electron microscopy and atomic force microscopy using dc-poled conductive tips. The responsible mechanism for the self-organized growth of fully-relaxed epitaxial SrZrO3 on the SrRuO3 ripple tops is identified as geometric shadowing induced by both the surface template morphology and the broadening of the angular distribution of the flux of incident particles. The latter process reflects the interactions between the deposition gaseous atmosphere (here molecular oxygen is at pressures approximate to 10(-1) mbar) and the ejected plume of laser-ablated particles. The broadening, as estimated from the average scattering angle of the particles within incident flux measured in an artificial shadowing experiment, served as input to simulate numerically the morphological evolution of the resulting nanostructured system, wired SrZrO3/rippled SrRuO3/SrTiO3