TOTAL ENERGY CALCULATIONS OF DIMER RECONSTRUCTIONS ON THE SILICON (001) SURFACE

Pseudopotential total energy calculations of dimer reconstructions on the silicon (001) surface are reported. We have calculated the energy of the ideal unreconstructed surface and the energies of the (2 × 1) symmetric dimer, the (2 × 1) buckled dimer, the p(2 × 2) alternating buckled dimer, the (2 × 4) single missing dimer, the (2 × 2) single missing dimer and the (2 × 4) double missing dimer surfaces. Our calculations give the p(2 × 2) alternating buckled dimer surface as the lowest energy reconstruction of those considered. The double missing dimer defect is found to be very high in energy. The energy cost of removing one dimer in every four from the symmetric dimer surface, forming a (2 × 4) missing dimer reconstruction, is only 0.28 eV per dimer removed. We suggest that single missing dimer defects might be a feature of the ground state of the silicon (001) surface. © 1990.