Experimental determination of the strain potentials on vicinal Si(001) surfaces

High-resolution low-energy electron diffraction measurements of the step structure of vicinal Si(001) as a function of both miscut angle and temperature are analyzed in terms of a one-dimensional model describing an SB step moving in the potential existing between two straight SA steps. The model includes kink and corner energies plus a generic strain potential caused by the surface reconstruction and the rebonding of atoms at the steps. Fits to the data confirm that the strength of the direct step-step interaction between steps increases continuously as the mean terrace width diminishes. At high temperature and large miscut angles, a one-dimensional model becomes unsatisfactory. Meandering of the SA steps even for very narrow terrace widths is the likely cause.