The growth of Pb nanocrystals on Si(111)7×7 : Quantum size effects

Surface X-ray scattering and scanning–tunneling microscopy experiments, performed in situ, are used to investigate the influence of quantum size effects on the growth of Pb on the Si(111)7×7 surface. It is demonstrated that the structure of Pb islands and the associated wetting layer are consistent with the effects of quantum confinement. Moreover, these effects lead to novel behavior for the coarsening evolution of the Pb islands. For example, Ostwald ripening is not observed due to a breakdown of the classical Gibbs–Thomson effect. An unanticipated strong dependence on the deposition flux rate is found and we measure island decay times that are orders of magnitude faster than predicted. These results have important implications for understanding and controlling the growth of nanostructures.