A comparative study of clean and Bi-stabilized InP(1 0 0)(2 × 4) surfaces by the core-level photoelectron spectroscopy

The bismuth-stabilized (2 × 4)-reconstructed InP(1 0 0) surface [Bi/InP(1 0 0)(2 × 4)] has been studied by synchrotron-radiation core-level photoelectron spectroscopy. The spectra are compared with previous core-level data obtained on a clean InP(1 0 0)(2 × 4) surface. The findings support that the P 2p surface-core-level shift (SCLS) of the clean InP(1 0 0)(2 × 4), which has higher kinetic energy than the bulk emission, arises from the third-layer P atoms and that the second P 2p SCLS, which has lower kinetic energy than the bulk, arises from the top-layer P atoms. Similar In 4d SCLSs are found on the clean and Bi-stabilized InP(1 0 0)(2 × 4) surfaces, indicating that these shifts contain contributions of the In atoms that lie in the second and/or fourth layers. In addition to this, the results improve our understanding of the atomic structure of the Bi/InP(1 0 0)(2 × 4) surface and lead to refined surface models which include Bi-Bi and Bi-P dimers.