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 × 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 × n reconstructions. The formation of vacancy clusters is favored. A rebonded SB step is preferred on the clean Si(100) while a nonrebonded SB 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).