Unusual island structures in Ag growth on Si(100)-(2×1)

A detailed study of the early stages of nucleation and growth of Ag on Si(100)-(2×1) surfaces at room temperature using ultrahigh-vacuum high-resolution transmission-electron-microscopy imaging and diffraction is presented. While diffraction patterns suggest only a mixed epitaxy, off-zone axis images clearly reveal three-dimensional Ag islands. Aside from simple single-crystal structures, these islands are also seen to include multiply twinned morphologies with different epitaxies relative to the substrate; details of these are discussed.