Step free energies, surface stress, and adsorbate interactions for Cl-Si(100) at 700 K

Abstract

The evolution and equilibrium morphology of Si(100) with 0.1 monolayer of adsorbed Cl was studied at 700 K with variable temperature scanning tunneling microscopy. Chlorine caused surface roughening with monolayer pits and regrowth islands. The aspect ratio of these features then increased with their size because of the surface-stress anisotropy. By analyzing the equilibrium feature shape as a function of size, we found that the ratio of step free energies for A- and B-type steps was Fb/Fa = 2.44 for regrowth islands and 3.33 for pits. These ratios are higher than for clean Si(100), Fb/Fa = 2.13, because the steps are destabilized.