Sb overlayers on (110) surfaces of III-V semiconductors: Total-energy minimization and surface electronic structure

The atomic geometry, chemical bonding, and surface-state eigenvalue spectra are predicted for saturated (1×1) ordered monolayers of Sb on the (110) surfaces of GaP, GaAs, GaSb, InP, InAs, and InSb. These predictions are based on an extension of the ${\mathrm{sp}}^3$ $s^{\mathrm{*}}$ tight-binding model to encompass the calculation of total energies and hence the identification of minimum-energy surface geometries. The predicted geometries are in good correspondence with those obtained from low-energy electron diffraction for the only two cases in which the latter are known, i.e., GaAs and InP. With the use of these predicted geometries, the energy-dispersion relations of the surface states are evaluated throughout the surface Brillouin zone and compared with their clean-surface analogs. Examination of the electronic structure of these Sb-substrate systems reveals a novel type of bonding not found in either bulk III-V semiconductors or molecular III-V analogs.