Abstract
This work investigates the adsorption of diatomic interhalogens (XY = ICl and IBr) and hydrogen halides (HX = HBr and HCl) on Si(100) and Ge(100) surfaces by synchrotron radiation core-level photoemission and scanning tunneling microscopy (STM). It was found that mixed adsorbates (X and Y) or (H and X) each terminate a surface dangling bond while preserving the dimmer structure. The coverage ratios of Cl/I and Br/I are slightly below the stoichiometric value of 1 for Si(100):ICl (the ICl-passivated Si(100) surface) and Si(100):IBr, respectively, but ∼1.4 for Ge(100):ICl. The X/H coverage ratios for HCl and Si(100):HBr are also less than 1. The mixed adsorbate system form well-ordered or partially ordered structures for chlorine-contained molecules on Si(100), but no adsorbate ordering is observed for bromidecontained molecules. In a sequel paper, we will present ab initio calculations for the energetics for the Si(100) surface with two mixed adsorbates to provide a more in-depth understanding of the experimental findings presented here. © 2011 American Chemical Society.