Step-induced elastic relaxation and surface structure of the Si(7710) surface

We have studied by Grazing Incidence X-ray Diffraction (GIXD) the strain field induced by periodic triple steps on a Si(7710) surface that is a vicinal of Si(111) surface 10° misoriented towards the [ 11 ¯ 2 ] direction. We find that the strain field induced by the triple steps is well described by an elastic model in which the steps are modelized by parallel rows of buried elastic dipoles. The best fit of the experimental results is reached on the basis of the (7710) surface structure model proposed by Teys et al. (Surface Science 600 (2006) 4878). The so-obtained dipole characteristics are the dipole amplitude (decomposed in a stretch component PT = 1.5 nN and a torque component PS = 0.2 nN) as well as the lever arm Ω = 170° and force Φ = 81° orientations of the dipole. We also determine the prefactor of the elastic interaction energy between triple steps Ael. = 0.52 eV Å we discuss in the light of other independent measurements.