No abstract

InAs͑001͒-c͑8ϫ2͒, InSb͑001͒-c͑8ϫ2͒, and several reconstructions of GaAs͑001͒ are exposed at room temperature to iodine molecules ͑I 2 ͒. Low-energy electron diffraction ͑LEED͒ and synchrotron soft x-ray photoelectron spectroscopy ͑SXPS͒ are employed to study the surfaces as a function of I 2 dose and sample anneal. In the exposure range studied, GaAs and InAs become saturated with I 2 , resulting in removal of the clean surface reconstruction and the formation of a very strong 1ϫ1 LEED pattern. Iodine bonds primarily to the dominant elemental species present on the clean surface, whether it is a group-III or-V element. The InSb͑001͒-c͑8ϫ2͒ reconstruction is also removed by I 2 adsorption, and a strong 1ϫ1 LEED pattern is formed. SXPS data, in conjunction with scanning tunneling microscopy images, however, reveal that InSb͑001͒-c͑8 ϫ2͒ does not saturate at room temperature, but is instead etched with a preferential loss of In. Heating the iodine-covered group-III-rich InAs͑001͒-c͑8ϫ2͒ and InSb͑001͒-c͑8ϫ2͒ surfaces causes removal of the iodine overlayer and transformation to a group-V-rich reconstruction. When the iodine-covered As-rich GaAs͑001͒-c͑2ϫ8͒ surface is heated to remove iodine, however, the c͑2ϫ8͒ reconstruction is simply regenerated. ͓S0163-1829͑96͒12427-9͔

No abstract

No abstract

The room-temperature reaction of Cl 2 with GaAs͑001͒-4ϫ6,-c(2ϫ8), and-c(4ϫ4) surfaces is studied with synchrotron soft x-ray photoelectron spectroscopy. The chemical composition of the reacted surfaces is found to depend on the stoichiometry of the starting surface. In all cases, the reaction occurs stepwise, with Ga and As monochlorides formed prior to the dichlorides. The Ga-rich surface is initially more reactive than either of the As-rich surfaces and it forms more GaCl than the As-rich surfaces, which instead form more AsCl. The sticking coefficient for chlorine on GaAs͑001͒ decays exponentially with coverage. A contribution from Cl atoms comprising the surface dichlorides is identified in the Cl 2 p core-level spectra.