SURFACE-SHIFT LOW-ENERGY PHOTOELECTRON DIFFRACTION - CLEAN AND HYDROGENATED GAAS(110) SURFACE-STRUCTURE RELAXATION

Surface-shift low-energy photoelectron diffraction has recently been revealed as a powerful tool for the determination of surface structures. We have applied this method to study clean and hydrogenated (1/4 of monolayer) GaAs(110) surfaces. A recently developed renormalized multiple-scattering theory [M. Biagini, Phys. Rev. B 48, 2974 (1993)] has been applied to the interpretation of As 3d polar spectra. Numerical computations have been carried out for several surface geometries, corresponding to different buckling angles and surface bond lengths. We have obtained a buckling angle =26°and 6°for clean and hydrogenated surfaces, respectively. As far as surface bond lengths are concerned, changes within +2% for the clean surface and ideal bond lengths for the hydrogenated surface were found.