Energy scaling and surface patterning of halogen-terminated Si(001) surfaces

We show that steric repulsion energies between halogen dimers on a passivated Si(001) surface scale with square of the principle quantum number (or period) it of the halogen, and arise principally from bonding with Si substrate. We exemplify the scaling from previously calculated steric interactions of F, Cl, and Br, predict the interactions for I and At, and then verify the prediction by direct density-functional calculations. From the energetics, we explain the patterning of the halogen-terminated Si(001), for a better understanding of the halogen-roughening process, and predict a crossover to a new vacancy-line defect for large halogens. (c) 2005 Elsevier B.V. All rights reserved.