Surface Phonons on GaAs(110) Measured by Inelastic Helium Atom Scattering

Abstract

Surface phonon dispersion relations have been measured by He-atom inelastic scattering for in situ cleaved GaAs(110). Besides the expected Rayleigh mode and a mode at 13 meV at the Brillouin-zone boundary a third mode with a wave vector independent energy of 10 meV has been observed. This finding is very similar to our recent results for the reconstructed Si(111) (2 × 1) surface. In both cases the observations are unexpected for the presently accepted surface structures.