No abstract

Polar-angle resolved Auger electron emission and related modeling have been used to determine quantitative details of composition and diffusion phenomena in the Cu/Si(111) and Au/Si(111) interface systems. The extent of Si outdiffusion increases with coverage in a gradual fashion for Au, with characteristic diffusion lengths (CDL) ranging from 18% of the overlayer thickness at a 2 Å coverage to 39% at 20 Å. In contrast, Si CDL values in Cu increase abruptly from 20% of the overlayer thickness at 2 Å to ∼35% at coverages from 5 to 20 Å. Au diffuses deeply into the Si substrate, whereas Cu indiffuses only slightly (CDL=1–2 Å). These model predictions are consistent with the more substantial lattice disruption brought about by Au, leading to no long-range order in the overlayer, and the persistent diffusion of Si to the surface of 150-Å-thick Au overlayers.