Low energy electron diffraction, Auger electron spectroscopy and angle-resolved photoemission from silver films on Si(100) and Si(111)

Abstract

We studied the growth of thin silver films on Si(100)2 × 1 and Si(111) 7 × 7 between room temperature and 300 °C. At room temperature and with a silver flux of 2.4 × 10 12 atoms s -1 cm -2 a nearly exponential dependence of the Si L 2,3 VV and Ag M 4 VV Auger intensities indicates layer-by-layer (Frank-van der Merwe) growth up to a film thickness of a few monolayers. With increasing coverage θ silver grows in form of three-dimensional islands even at room temperature. In spite of the existence of the well-known Si(111)−(√3 × √3)R30° Ag surface structure after annealing (which we observe for θ = 1) we did not find an ordered Si-Ag interface layer for silver on Si(100). For elevated temperatures the growth of this system may therefore be described by the Volmer-Weber (pure three-dimensional island growth) mechanism, whereas silver condenses on Si(111) according to the Stranski-Krastanov (interface layer plus three-dimensional islands) growth mode.