Reaction of I-2 with the (001) surfaces of GaAs, InAs, and InSb .1. Chemical interaction with the substrate

• InAs(001)-c(8x2), InSb(001)-c(8x2), and several reconstructions of GaAs(001) are exposed at room temperature to iodine molecules (I-2). Low-energy electron diffraction (LEED) and synchrotron soft x-ray photoelectron spectroscopy (SXPS) 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 1x1 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 InSb(001)-c(8x2) reconstruction is also removed by I-2 adsorption, and a strong 1x1 LEED pattern is formed. SXPS data, in conjunction with scanning tunneling microscopy images, however, reveal that InSb(001)-c(8x2) does not saturate at room temperature, but is instead etched with a preferential loss of In. Heating the iodine-covered group-III-rich InAs(001)-c(8x2) and InSb(001)-c(8x2) surfaces causes removal of the iodine overlayer and transformation to a group-V-rich reconstruction. When the iodine-covered As-rich GaAs(001)-c(2x8) surface is heated to remove iodine, however, the c(2x8) reconstruction is simply regenerated.

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