Possible appearance of superconductivity on Si(1 0 0) surface

A two-leg ladder Hubbard model with three Fermi surfaces are studied as a model Hamiltonian of a Si(0 0 1) surface, on which STM experiments [Phys. Rev. B 61 (2000) R5078; Surf. Sci. 452 (2000) L318] recently reported that the p(2×1) symmetric dimer phase is stable at low temperatures. The fluctuation-exchange method is adopted in order to take account of the effects of on-site Coulomb interactions. The electronic structures are discussed and an unconventional even-parity superconductivity through large antiferromagnetic spin fluctuations is found for a wide range of doping. Other possible electronic states with large superconducting fluctuations are also discussed [J. Phys. Soc. Jpn. 69 (2000) 1962].