Shape of atomic steps on Si(111) under localized stress

Localized elastic strain in Si crystal is artificially produced by buried silicon oxide inclusions formed beneath a lithographically defined area by oxygen implantation. The Si crystal with local strain is annealed at 1180-1260 degreesC, and the shape of atomic steps at a vicinal Si(111) surface is observed by in situ ultrahigh-vacuum secondary-electron microscopy and ex situ atomic force microscopy. The step shape is determined by the balance between the elastic stress at the surface and the Gibbs-Thomson effect-the decrease of the chemical potential mu related to the step curvature. The shape analysis enables us to estimate the strain-related contribution to the Gibbs free energy density DeltaG/A=8.3x10(-5) J/m(2).