Elastic cost of silicon step rebonding

Abstract

We study by grazing incidence x-ray diffraction the strain field induced by periodic double steps on a Si(1 1 15) surface that is a vicinal of a Si(001) surface misoriented by $5.{4}^{\ensuremath{\circ}}$ towards the $\ensuremath{\langle}110\ensuremath{\rangle}$ direction. The best fit of the experimental structure factors is reached on the basis of the rebonded ${D}_{B}$ step edge model and the displacement field is well characterized assuming that steps are described by parallel rows of extended buried elastic dipoles. The dipole characteristics are the dipole position with respect to the step edge, the dipole amplitude ($2.0\ifmmode\pm\else\textpm\fi{}0.5$ nN), and the lever arm $\mathrm{\ensuremath{\Omega}}=5.{3}^{\ensuremath{\circ}}$ and force $\mathrm{\ensuremath{\Phi}}=3.{7}^{\ensuremath{\circ}}$ orientations. We show that the dipole is dominated by a large stretch component localized between the lower and the upper corners of the step, which we assign to the presence of the rebonded atom at the step.