Anisotropic conductance oscillations in Pb films on Si(557)

Abstract

We correlate in this study the growth of Pb films on the stepped Si(557) surface at temperatures of 70 K, studied by low-energy electron diffraction, with the properties of electronic transport, measured by a macroscopic four-point probe technique. Despite a large lattice mismatch, layer-by-layer growth is observed, as most obvious from the characteristic oscillations in conductance with layer periodicity, incipient with the first monolayer both along and across the step direction. These findings demonstrate that lateral misfits (here almost 10%) in heteroepitaxial systems can be effectively compensated by substrate steps and can change the growth mode with respect to flat surfaces. While structurally the layers appear to be isotropic starting already with the third layer, anisotropy is seen in transport up to at least six monolayers with functional dependencies of conductance varying with layer thickness and measurement direction. Maxima of conductance oscillations up to five monolayers do not coincide with completion of individual layers. They are characteristic for the close coupling of structure and quantum effects. © 2010 The American Physical Society.