Structure of the Ag/Si(111) surface by scanning tunneling microscopy

We present the first real-space images, obtained by scanning tunneling microscopy, which show the ordered atomic structures of the Ag/Si(111) surface for several submonolayer coverages. The (3 × 3) R30°surface is shown to be of the honeycomb structure, and the room-temperature coverage is determined to be theta=(2/3). The (1×3) overlayer consists predominantly of rows of Ag atoms separated by two empty rows. At low coverage the surface shows long-range 7×7 order, but patches occur within the 7×7 cells whree Si adatoms are absent. © 1987 The American Physical Society.