Surface Structure Formed by the Reaction of Monomethylgermane on Si(001) Surface

The surface reaction of monomethylgermane (MMGe) on a 2°-off-surface Si(001) wafer and the subsequent nanodot formation were analyzed at an atomic scale by scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED). By nucleation after the formation of a c(4×4) surface structure, which is formed by carbon diffusion into the surface layer, uniform high-density nanodots of 9×1011 cm-2 density and 9 nm average diameter were successfully formed. By X-ray photoelectron spectroscopy (XPS), the coexistence of Ge–Ge (or Ge–Si) and Si–C bonds was confirmed, and in particular, the Ge–Ge (or Ge–Si) bonds were confirmed to exist on the surface layer by angle-resolved XPS.