Competitive Pairing and the Chemistry of Coadsorbed Hydrogen and Halogens onGe(100)

摘要

The chemistry of coadsorbed H and X (X=Cl, Br) on semiconductor surfaces isimportant in epitaxial growth of silicon from chlorosilanes and of Si(x)Ge(l-x) alloys, in hydrogenating/ halogenating cycles in atomic layer epitaxy, and also provides an interesting model system, yet has received little attention to date. We have investigated the interaction of HCl and HBr with Ge(100) by temperature-programmed desorption, and find that H2, HCl and HBr each desorb with near-first-order kinetics near 570-590 K and that GeC12 and GeBr2 desorb with near-second-order kinetics near 675 K and 710 K, respectively. Analysis of the desorption kinetics of H2 and HX leads to the conclusion that adsorbed H and X atoms pair preferentially in a qualitatively similar way as H atoms adsorbed alone on Ge(100)2xl or Si(100)2xl and that pairing of H+X occurs in competition with pairing of H+H.... Germanium, Hydrogen, Pairing, HCI, HBr, Surface chemistry, Kinetics.