High-resolution core-level photoemission study of Ge(1 1 1)2 × 1-Sb and Ge(1 1 1)(√3 × √3)R30°-Bi reconstructions

Using high-resolution core-level photoelectron spectroscopy with synchrotron radiation, we have studied Ge(1 1 1)2 × 1-Sb and Ge(1 1 1)(√3 × √3)R30°-Bi reconstructions formed at the metal coverage of 1 and 1/3 monolayers, respectively. The spectral line shape analysis shows that for the both surfaces, the Ge 3d emission includes one component, giving evidence for the bulk-terminated structure of the Ge substrate in these phases. The Bi 5d emission from the Ge(1 1 1)(√3 × √3)R30°-Bi surface reveals an intense component related to the Bi atoms at the T4 site in the √3 structure, in agreement with previous ab initio calculations. Another small Bi 5d component is assigned to Bi-Bi bondings in metallic Bi clusters. The Sb 4d spectra of the Ge(1 1 1)(2 × 1)-Sb surface can be reproduced well by a single component, suggesting that the Sb atoms in the Seiwatz chains have similar bonding configuration.