Correlations between In Situ Conductivity and Uniform-Height Epitaxial Morphology in Pb/Si(111)-(7×7)

The growth of Pb on Si(111)-(7×7) at temperatures from 72 to 201 K has been investigated using in situ electrical resistivity measurements and scanning tunneling microscopy. For temperatures T>140  K the specific resistivity ρ(θ) versus coverage θ shows an unusual "hump," instead of the expected monotonic decrease with θ. This novel result correlates well with the formation of uniform height eight-layer Pb islands and the superdiffusive motion of the wetting layer, despite the low temperatures. A model of the film resistivity as two resistors in series, the amorphous wetting layer and the crystalline islands, explains quantitatively the resistivity dependence on θ.