Growth and characterization of Si and Ge clusters on ordered C-60 overlayers

We use in situ fabricated ordered C-60 overlayers on Si and Ge surfaces as templates to grow isolated Ge and Si clusters, respectively. The growth processes are monitored and characterized by scanning tunneling microscopy, Anger spectroscopy, and low energy electron diffraction. Si and Ge clusters nucleate in the interstices of the C-60 layer, and reach a typical lateral size of similar to 10 Angstrom before coalescing. Auger spectra of small Si clusters show an enhanced contributions from states of s symmetry, reflecting nontetrahedral coordination of Si atoms in clusters. Room temperature tunneling spectroscopy of isolated clusters reveals an enlarged band gap consistent with the effect of quantum confinement, and a quantized conductance attributable to the Coulomb blockade phenomena in a tip/cluster/substrate double barrier junction. (C) 1997 American Vacuum Society. [S0734-211X(97)03904-8].