Growth of Ag on the Bi-terminated Ge/Si(1 1 1) surface

The presence of a Bi layer during Ge epitaxy at the Si(1 1 1) surface suppresses Si–Ge intermixing and also allows us to distinguish between Si and Ge in scanning tunneling microscopy at the atomic level. In our investigation, we explored the possibility of a selective growth of Ag either on a Ge area or a Si area. We found that a chemically selective bonding of Ag to Si or Ge at the prestructured Ge/Si surface does not occur. Due to the strong passivation of Si and of the Ge surfaces by a layer of Bi at room and elevated temperatures Ag collects into 3D islands without being incorporated into the surface. Co-deposition of Ag during the epitaxy of Ge on the Bi-terminated Si(1 1 1) surface also leads to an accumulation of Ag into 3D islands, while the remaining surface is covered by a layer of Bi.