Atomic structure of Si(100) surfaces

The structure of a clean Si(100) and a Ni-contaminated Si(100) was investigated using scanning tunneling microscopy. The clean Si(100) shows the 2 x 1 reconstruction with a surface dimer vacancy density less than 2%. The major defects on the clean surface are a single dimer vacancy and the C defect. A small amount of Ni on the surface drastically changes the surface structure and produces 2 x n reconstructions. The formation of vacancy clusters is favored. A rebonded S-B step is preferred on the clean Si(100) while a nonrebonded S-B step with a split-off dimer is mainly observed on the Ni-contaminated Si(100) and in the vicinity of dimer vacancies of the lower terrace on the clean Si(100).