BEHAVIOR OF STEPS ON SI(001) AS A FUNCTION OF VICINALITY

The surface step morphology of the Si(001) surface as a function of mi scut angle between 0.3-degrees and 5.25-degrees has been investigated using scanning tunneling microscopy. On samples with large average ter race widths, the kinks in the steps behave independently and the intri nsic step energy can be determined from the kink-length distribution w hich follows simple Boltzmann statistics. For wide terraces the large- scale meandering of the steps is governed by the long-range strain fie lds caused by the anisotropic surface stress tensor. Here the step sep aration 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 nu mber of long kinks. As steps get closer together, a short-range direct step-step interaction arising from the local strain due to the rebond ing of the SB step begins to influence the step distribution. The sens e of this interaction is such that the rough SB step is attracted to i ts downhill neighbor. Images and terrace-width distributions of surfac es for which the miscut angle is great enough to measure an appreciabl e increase in the percentage of double atomic-height steps are used to provide a description of the evolution of the surface from one contai ning single-height to mostly double-height steps.