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 GaA s(001) are exposed at room temperature to iodine molecules (I-2). Low- energy electron diffraction (LEED) and synchrotron soft x-ray photoele ctron spectroscopy (SXPS) are employed to study the surfaces as a func tion of I-2 dose and sample anneal. In the exposure range studied, GaA s and InAs become saturated with I-2, resulting in removal of the clea n surface reconstruction and the formation of a very strong 1x1 LEED p attern. Iodine bonds primarily to the dominant elemental species prese nt 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 s canning 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 i odine overlayer and transformation to a group-V-rich reconstruction. W hen the iodine-covered As-rich GaAs(001)-c(2x8) surface is heated to r emove iodine, however, the c(2x8) reconstruction is simply regenerated .