Surface phonons of clean and hydrogen terminated Si(1Â 1Â 0) surfaces

We report an investigation of the dynamical properties of clean and monohydride-terminated Si(1 1 0) surfaces, measured by means of high resolution electron energy loss spectroscopy (HREELS). On both surfaces a number of surface phonons is observed and successfully assigned to predicted modes. A (1 × 5) reconstruction is found to be the stable surface phase corresponding to monohydride coverage of Si(1 1 0). For the Si-H stretching and bending bands of this monohydride Si(1 1 0) surface we find a relatively strong dispersion along the [11¯0] direction. Apparently, this is related to the coupling of oscillators along the Si chains of the (1 1 0) surface. In addition, surface vibrations induced by adsorbed residual gases are measured and analysed.