Anisotropic electronic conduction in metal nanofilms grown on a one-dimensional surface superstructure

We performed in situ conductivity measurements by multiple microscopic probes of Ag nanofilms grown on a periodic array of indium atomic wires on Si(111). Within the investigated thickness range the transport properties differ markedly from the bulk case. The ratio between the in-plane conductivity along and perpendicular to the In wires is 1.4 for the 3 monolayer (0.7 nm) thick Ag film and approaches unity with increasing film thickness. The observed anisotropy at the initial stage of the film growth is far larger than expected from the quasi-one-dimensional quantum well electronic structure of the films and ascribed to the carrier scattering at the film/vacuum and film/substrate interfaces. Our findings show that an ordered monolayer inserted at the interface enables drastic changes of the transport behavior of the whole metal nanofilm.