Epitaxial growth of silver on an Si( 111) √3 × √3 Au surface at room temperature

Abstract

Growth of Ag on an Si(111) √3 × √3 Au surface was investigated by reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES). At an initial stage of Ag deposition, the √3 × √3 structure fades into the diffuse background. Subsequently, a faint pattern from Ag(111) appears at 0.8 monolayers (ML, 1 ML = 1.39 × 10 15 atoms cm −2). At 7 ML growth the RHEED pattern shows a flat Ag(111) surface, although RHEED oscillations are hardly observed during growth. For Ag deposition onto an amorphous-like surface covered by 0.6 ML Au on the √3 × √3 surface, RHEED intensity oscillations are observed during growth. At an initial stage of Ag growth on the surface, extra streaks are observed in the RHEED pattern, continuing up to about 6 ML deposition. During the appearance of the extra streaks, the Auger spectrum of Si-LVV splits into two peaks at 88 and 92 eV. Small Si-LVV, 92 eV, and Au-NOO peaks remain up to 10 ML and the oscillation amplitude of the RHEED intensity is not damped up to 10 ML coverage. In the case of Ag deposition onto the √3 × √3 Au surface, since no segregation of Si and Au atoms is observed, it is concluded that the silicide and Si segregations induce two-dimensional nucleation on the surface.