(110) surface states of GaAs: Sensitivity of electronic structure to surface structure

The (110) surface states of GaAs for three models of surface relaxation are examined by the tight-binding method. Although these relaxations, obtained from analyses of low-energy-electron-diffraction data, involve similar atomic displacements, they give rise to noticeable differences in the relative positions of some surface states when these states are identified by their orbital symmetries. All three relaxations are found to completely remove all surface states from the band gap and to give rise to new surface states. Our calculations indicate the presence of five to six filled and four empty surface states. Results for energies, local densities of state, and the orbital characters of these states are given and compared to experimental data.