Angle resolved photoemission study of the c(2 × 2)Si overlayer on Fe(100)

Abstract

Angle resolved photoemission experiments utilizing polarized synchrotron radiation were performed to study the electronic structure of valence levels of Si segregated in a c(2 × 2) overlayer on the α-Fe(100) surface. The spectra were taken at varying photon energies (14 ⩽ ω ⩽ 40 eV), in dependence on the polarization of the incoming light, and as a function of the photoelectron emission angle in the symmetry directions T̄M̄' and T̄X̄' of the surface Brillouin zone. Evaluation of the photoemission data shows that the Si 3p levels form energy bands for the ordered c(2 × 2) overlayer on Fe(100). The initial state energy of the Si 3p states depends on k ∥ being measured. At T̄ a bonding Si 3p z state (a 1 symmetry) and an antibonding Si 3p x p y state (e symmetry) is analyzed, which are separated by 0.8 eV in binding energy. In going from T̄ to M̄' the Si 3p z induced level disperses ~ 0.8 eV to lower initial state energies. In the T̄X̄' direction the overall Si 3p band width is approximate 1.3 eV. Though the interaction between silicon and iron surface atoms are relatively weak compared to Fe(100)-c(2 × 2)S, modifications in the Fe derived valence band states occur, including the formation of a hybridization state located 1.4 eV below E F.