Reflectance-difference spectroscopy of semi-insulating GaAs(110) around the fundamental gap - art. no. 085309

We report on a theoretical model to describe reflectance-difference (RD) sp ectra for the (110) surface of zinc-blende semiconductors due to anisotropi c strains induced by 60 degrees dislocations. We obtain expressions for the RD spectrum at critical points of Gamma symmetry that predict second-energ y-derivative RD line shapes as far as the strain-induced energy shifts are small compared to spectra broadening energies, The second-derivative line s hape contrasts with the first-derivative line shape observed previously for the GaAs(001) surface. We further report on experimental RD spectra of sem i-insulating GaAs(110) in the 1.2-1.6 eV energy range and show that such sp ectra comprise a component that is well described by our theoretical model, Results obtained in the present work prove the existence of dislocation-in duced components in RD GaAs spectra. We expect that they will contribute to further development of RD spectroscopy as a surface and near-surface optic al probe for zinc-blende semiconductors.