Structure, Stability, and Origin of (2×n) Phases on Si(100)

Phases with ($2\times n$) structure ($6<n<\mathrm{}10\mathrm{}$) can be formed on Si(100) by rapid quenching from high temperatures. The nominal (2×7) phase has been investigated by high-resolution low-energy electron diffraction. The structure involves two atomic levels, is metastable, and decays with first-order kinetics. The structure can be explained by ordering of excess missing-dimer defects, which apparently are present on the surface with any of the standard surface preparation techniques for Si(100).