Chemisorption of iodine on In- and Sb-terminated InSb(001)

The chemisorption of I2 on the In-terminated InSb(001)-c(8×2) and Sb-terminated InSb(001)-c(4×4) surfaces was investigated with synchrotron-based soft X-ray photoelectron spectroscopy and low-energy electron diffraction. For both terminations, the predominant species formed is InI2, and the surfaces become disordered. Further analysis suggests that iodine adsorption induces In to migrate from the bulk up to the surface. These results are compared to results for similar systems. It is suggested that the ability of InI2 to form on the surface is critical in determining the reaction pathway. InI2 is readily formed because of the relatively large lattice spacing and the relatively weak InSb bond strength, as compared to other III–V materials. Thus, the reaction of I2 with InSb can proceed more completely, and the surface product distribution more closely reflects the bulk chemical thermodynamics.