Experimental evidence for quantum-size-effect fine structures in the resistivity of ultrathin Pb and Pb-In films.

Abstract

The resistivity of ultrathin single-crystalline Pb and Pb-In layers with thicknesses d smaller than the bulk mean free path l, is measured during deposition onto Si(111)-(6\ifmmode\times\else\texttimes\fi{}6)Au surfaces at about 110 K. The structure of the layers is monitored by reflection high-energy electron diffraction (RHEED). Oscillations of the RHEED specular beam intensity are highly correlated with fine structures of the resistivity. The quantum-size-effect theory is used for a quantitative analysis of the data. The fine structure, volume impurities, small-scale roughness, and large-scale thickness fluctuations are taken into account. The impact of the layer-by-layer growth mode of ultrathin metal films on the thickness dependence of the resistivity is discussed.