Terrace-width distributions on vicinal Si(111)

Abstract

Using scanning tunneling microscopy, we have quantitatively characterized the configurations of steps on vicinal Si(111) surfaces misoriented by 1.2 degrees and 2.3 degrees towards the (1- 1- 2) direction. The measured terrace-width distributions are strongly peaked, consistent with predictions for thermally wandering steps. However, the distributions are much narrower than predicted for the simple terrace-step-kink model, indicating that the steps interact with energetic short-range repulsions. The magnitude of this energetic repulsion is gauged from a Gaussian fit to the data. The width of the distribution scales with step density as expected for repulsions which decay as the inverse square of step separation.