ASYMMETRIC SB DIMERS ON THE 1-ML GE-TERMINATED SI(100) SURFACE

MeV transmission ion channeling has been used to investigate the structure of 0.95 ML of Sb deposited on 0.81 ML of Ge grown pseudomorphically on the Si(100) surface. It is shown that the sb overlayer is composed of asymmetric dimers, in contrast to the symmetric dimers reported in the literature on the Sb-terminated clean Si(100) surface. It is further shown that the Ge reconstruction is lifted upon Sb deposition and Ge then occupies a near-bulk site. The characterization of the underlying Ge layer provides additional and convincing evidence for Sb dimer asymmetry.