Electronic and structural properties of the InP(1 0 0)(2 × 4) surface studied by core-level photoemission and scanning tunneling microscopy

The (2 × 4)-reconstructed InP(1 0 0) surfaces have been investigated by scanning tunneling microscopy (STM) and synchrotron-radiation core-level photoelectron spectroscopy. STM observations show that the α2 model describes the atomic structure of the InP(1 0 0)(2 × 4) surface in a limited range of the surface-preparation conditions, as predicted theoretically but not previously observed. STM results also support the accuracy of the previously found mixed-dimer structure for the InP(1 0 0)(2 × 4) surface under less P-rich conditions. A study of P 2p core-level photoelectron spectra, measured with different surface-sensitivity conditions, demonstrates that P 2p photoemission from the mixed-dimer InP(1 0 0)(2 × 4) surface consists of at least two surface-core-level-shift (SCLS) components which have kinetic energies approximately 0.4 eV higher and 0.3 eV lower than the bulk emission. On the basis of the surface-sensitivity difference between these SCLSs, they are related to the third-layer and top-layer P sites in the mixed-dimer structure, respectively.