SURFACE-STRUCTURES AND CONDUCTANCE AT INITIAL-STAGES IN EPITAXY OF METALS ON A SI(111) SURFACE

In situ measurements of surface conductance, combined with simultaneous observations of reflection high-energy electron diffraction, clearly demonstrated strong dependence of the conductance on the substrate-surface structures and epitaxial growth modes at initial stages of metal depositions on a Si(111) surface at room temperature. In the case of Ag deposition onto a Si(111)-square-root 3 x square-root 3-Ag surface, the resistance near the surface region showed steep decrease with small Ag coverage, while it scarcely changed for Ag deposition onto a clean 7 X 7-substrate. In the case of Au depositions onto Si(111)-5 x 2, square-root 3 x square-root 3, and 6 x 6-Au surfaces, the resistance greatly increased at the beginning, and then decreased during Au deposition. The resistance change for Au deposition onto a clean 7 x 7-surface was, on the other hand, much smaller at the same coverage region. These dependences of the surface conductance on the substrate-surface structures are understood in terms of the Fermi level pinning and band bending at each surface.