The surface step morphology of the Si(001) surface as a function of miscut angle between 0.3° and 5.25° has been investigated using scanning tunneling microscopy. On samples with large average terrace widths, the kinks in the steps behave independently and the intrinsic step energy can be determined from the kink-length distribution which follows simple Boltzmann statistics. For wide terraces the large-scale meandering of the steps is governed by the long-range strain fields caused by the anisotropic surface stress tensor. Here the step separation distributions can be described by a Boltzmann distribution of segments of the step moving in this strain potential. At intermediate average terrace widths, the distribution of kink lengths is influenced by the confinement between neighboring steps, which suppresses the number of long kinks. As steps get closer together, a short-range direct step-step interaction arising from the local strain due to the rebonding of the SB step begins to influence the step distribution. The sense of this interaction is such that the rough SB step is attracted to its downhill neighbor. Images and terrace-width distributions of surfaces for which the miscut angle is great enough to measure an appreciable increase in the percentage of double atomic-height steps are used to provide a description of the evolution of the surface from one containing single-height to mostly double-height steps.

• Received 17 March 1992

DOI:https://doi.org/10.1103/PhysRevB.47.13432