An experimental and theoretical investigation was made of the surface patterning of I-Si(100)-(2x1). Using scanning tunneling microscopy, I destabilization of Si(100)-(2x1) at near saturation was first examined. Dimer vacancies formed on the terraces at 600K, and grew into lines that were perpendicular to the dimer rows; termed vacancy line defects. These patterns were distinct from those induced by Cl and Br under similar conditions since the latter formed atom and dimer vacancy lines that were parallel to the dimer rows. Using first-principles density functional theory, the steric repulsive interactions associated with I were determined and it was shown how the observed defect patterns were related to these interactions. Concentration-dependent studies showed that the vacancy patterns were sensitive to the I concentration. Dimer and atom vacancy lines that were elongated along the dimer row direction were favored at lower coverages. Atom vacancy lines predominated at ~0.8ML, they co-existed with dimer vacancy lines at ~0.6-0.7ML, and dimer vacancy lines were exclusively observed below ~0.5ML. These surface patterns reflected the mean strength of the adatom repulsive interactions.

Cross-Over Energetics for Halogenated Si(100) - Vacancy Line Defects, Dimer Vacancy Lines and Atom Vacancy Lines. G.J.Xu, N.A.Zarkevich, A.Agrawal, A.W.Signor, B.R.Trenhaile, D.D.Johnson, J.H.Weaver: Physical Review B, 2005, 71[11], 115332 (7pp)