Atomic structure of Si(111) (√3¯×√3¯)R30°-B by dynamical low-energy electron diffraction

The geometric structure of Si(111) (√3¯×√3¯) R30°-B formed by annealing highly doped Si(111) samples was determined by low-energy electron diffraction. The optimal structure has the B atom occupying a substitutional $B_5$ site, different from adatom sites occupied by other group-III metals. Three-dimensional atomic coordinates and surface bond lengths have been determined. With B at the $B_5$ site, the compressive stress between Si and B atoms disappeared in the near surface region. The difference between an all Si √3 reconstruction structure stabilized by B doping with another structure observed by Ag doping is discussed.